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Wikijunior:Ancient Civilizations/Atlanteans

Remember! No one has proof that Atlantis really existed. Some people believe that Atlantis is a myth or legend, while others believe it really existed. Like any very old story, there may be some bits that have been made up over the years and other bits that are true. No one can be certain of the truth yet, but maybe one day evidence will be found and we'll find out for sure if the Atlanteans exist.

Who might they have been?
There was a Greek philosopher named Plato who told us the amazing story about the Atlanteans. His stories are our only source for knowing about these people. He said they lived somewhere on an island continent "Beyond the Pillars of Hercules". The Pillars of Hercules is an old name for the gap between Europe and Africa where the Atlantic Ocean joins the Mediterranean Sea. This would mean that Atlantis was somewhere in the Atlantic Ocean.

Plato said that the Atlanteans first walked into this world 11,000 years ago - that's a pretty long time ago! He also said that they were a very powerful, rich, noble race and that they were very clever scientists knowing things that nobody else did.

Some people think that the legend of the Atlanteans could have been based on the city of Minoans. Atlantis is a European myth so it is likely that the Atlantis stories were based on a European people. The Minoans lived near to Greece and volcanic activity in the area may have "destroyed" Minoan cities in historical times in a similar way to the destruction of Atlantis that Plato described.

Before Plato, even a simple bronze sword might have looked like cutting edge technology, so this may be where the part of the legend that says the Atlanteans were advanced came from. Minoan cities also saw a lot of technology from the Assyrians, Babylonians, and Egyptians because these people had to travel through the Minoan cities on their way to Greece. The knowledge and writing of these countries would have made the Minoans quite advanced in their learning as well. This theory seems to fit the legend well.

Which country they might of lived in

We do not know where Atlantis, the homeland of the Atlanteans was. There are many theories and speculations about its location and a lot of people from Europe and Africa claimed Atlantis was located in their land. What we know about Atlantis is that Plato described the Atlanteans' home as beyond the "Pillars of Hercules" (known as 'Straits of Gibraltar' now) on an island in the Atlantic Ocean. The Atlanteans may have lived on Thera an island off the coast of Greece.

What Plato said
Plato was a Greek scholar, and also like a student crossed with a teacher. He said that...

"Atlantis was established by the sea god Poseidon. Poseidon had ten sons. Poseidon's eldest son became the ruler of Atlantis. Atlantis was divided into ten sections and each of Poseidon's sons got the kingship of one. The capital city, also known as the City of Atlantis, was renowned for its excellence in science and engineering. The city was circular and surrounded by land and water. At the center of the city was a high mountain called Olympus where there was a temple dedicated to the god of the sea, Poseidon, with a golden statue of him driving a six winged horse."

This was the way Plato described the city of Atlantis. According to this description some think Atlantis was somewhere near the Azores Islands and that the Azores are the leftovers of destroyed Atlantis. However, there are an almost limitless number of places that people think it could be, some claim Cyprus is the remnants of Atlantis, while others claim it to be New Zealand, Tahiti, Cuba or one of many other possible locations.

The Legend
The original legend of Atlantis says that the City of Atlantis sank beneath the sea. Many scientists and treasure hunters say that this is possible, but most people think this is just a story. Since 1960 many divers and submarines have looked for this ancient city but so far nobody has found it.


text:
User talk:24.12.54.20

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license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: User talk:24.12.54.20


text: User talk:213.178.244.41

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text: User:Sceptre

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Talk:Japanese/Reader

Missing Japanese
There are a few sub-pages with stories in English. If anyone can find the Japanese, we can turn these into Japanese Readers.
 * /The Grateful Crane
 * /The Bamboo Princess
 * /The Tongue-cut Sparrow

Found Japanese texts
I found these books which were requested. If I ever find out how to make these, I will :

The Grateful Crane: http://www.e-hon.jp/btsurun/tsuj0.htm

The Bamboo Princess: http://etext.virginia.edu/japanese/taketori/AnoTake.html

The tongue-cut Sparrow: http://www.aozora.gr.jp/cards/000329/files/18378_12098.html

^_^

title: Talk:Japanese/Reader


text:
Template:Japanese/Rubywikt

()

title: Template:Japanese/Rubywikt


text:
Handbook of Genetic Counseling/1p36 Deletion Syndrome-1

1p36 Deletion Syndrome

Introduction

 * Introduce myself and acknowledge that I will be involved in their visit today.
 * Let them know that Counselor1 and Dr. Doktour will also be visiting with them today.
 * Small talk while walking to the room.
 * "What are your main concerns or questions that you would like addressed today?"

Interim History

 * Explain that all of their concerns will be addressed later in the session, but that I would like to update the medical and developmental history from her last visit in February.
 * Who is her pediatrician? Any other physicians?
 * Any serious illnesses, hospitalizations or surgeries since February?
 * Current Medications?
 * Immunizations up to date?

Review of Systems

 * Any diet or feeding concerns?
 * Any changes in skin pigmentation or birth marks?
 * Any heart concerns? (cardiologist found none)
 * Any bladder problems?
 * Any concerns about her hearing? Ear infections? PE tubes?
 * Any concerns with her behavior or sleep?
 * Any bowel problems? Constipation?
 * Any allergies?
 * Any concerns about vision or eyes?
 * Any concerns about seizures? Starring spells or repetitive behaviors?
 * Any other medical concerns (difficulty breathing)

Developmental Assessment

 * Language
 * How many words does she have in her vocabulary?
 * Is she learning to sign? How many signs does she know?
 * Does she combine words into two word sentences?
 * Does she follow one or two step commands?
 * Can she point to any body parts?
 * How well is she able to indicate her wants?
 * Gross Motor
 * Is she standing independently?
 * Is she cruising?
 * Is she walking? Up stairs?
 * Visual Motor
 * How well does she hold and manipulate a crayon?
 * Drink from a cup?
 * Uses a spoon to feed? Started using a fork?
 * Can she help undress or dress herself?
 * Social
 * Imitates housework?
 * Behavior? (Rocking)

 * How do you feel her development compares with other children?
 * Do you feel she is making progress?

Early Intervention

 * Ask about OT, PT and speech therapy.
 * How often?
 * Where is she receiving services?
 * What are they working on and what are the goals?
 * Is insurance covering these costs?
 * How do you think she is progressing?

Psychosocial Assessment

 * Are all your other children living at home?
 * Things must be really hectic attending all her appointments and services on top of having ____ other children at home. How does it all work out?
 * Do you have help from other family members or others?
 * Do you have contact with any other families with 1p36 deletion syndrome?

Etiology of 1p36 deletion syndrome (monosomy 1p36)

 * Caused by deletion of the most distal band of the short arm of chromosome1.
 * Most clinical manifestations are probably caused by the absence of one copy of a dose-sensitive gene and it is not possible to replace missing genes from chromosomes at this time.
 * Prevalence of this deletion is estimated to be 1 in 10,000 to as high as 1 in 5,000 (making it the most common terminal deletion)
 * Most cases result from sporadic deletions and are not inherited
 * 1p36 deletion syndrome is usually diagnosed through recognition of the symptoms and characteristics as well as lab testing. This is done using high resolution chromosome analysis, or FISH with a chromosome 1-specific subtelomeric probe. The deletion often doesn't show up clearly with standard cytogenetic banding techniques. (In one group studied, about half were missed with chromosome analysis)
 * Patients with a 1p36 deletion have different sized pieces of the chromosome missing and may result in phenotype variability
 * Severity of associated disorders varies, but the physical features are very similar
 * Degree of MR and ability to acquire complex speech is somewhat dependent on deletion size
 * Most deletions affect the chromosome inherited from the mother (68%), but there doesn't seem to be differences in the clinical manifestations based on whether the deletion is on the paternal or maternal chromosome.
 * Those with paternally derived deletions tend to have larger deletions than those with maternally derived deletions
 * Mechanism causing chromosome breakage is unknown

Characteristics

 * Children with 1p36 deletion syndrome are all unique individuals, but do have some common characteristics.
 * Distinct facial features including: small and pointed chin, flat nasal bridge, low-set ears, ear asymmetry, thickened ear helices, small head, deep-set eyes, large anterior fontanel, clinodactyly and/or short fifth finger
 * Most patients have mental retardation
 * Most patients have delayed growth and/or difficulty gaining weight. Some have difficulty with sucking and swallowing while others may not grow well even though they eat well. Some older children may become obese.
 * Most young children with 1p36 deletion syndrome have delayed development.
 * They sit up, walk and talk later than typical children.
 * Speech is severely affected with many patients learning only a few words
 * Other medical problems: hypotony (which may explain delayed motor skills), hearing loss, seizures, eye/vision problems, hypothyroidism, increased risk for neuroblastoma, heart defects (which have included cardiomyopathy, ductus arteriosus, tetralogy of Fallot, VSD), and orofacial clefting abnormalities,

Recurrence Risk for next pregnancy

 * The majority of patients with 1p36 deletion syndrome are isolated cases resulting from a de novo deletion. There have been reports of patients with 1p36 deletion syndrome whose parents have a balanced translocation.
 * Parents should be tested for chromosomal rearrangements because about 6% of parents with an affected child have a balanced translocation
 * Translocation increases the chances of having another child with a 1p36 deletion.
 * If no translocation is found the chances of having another child with a 1p36 deletion are very small

Prenatal Diagnosis

 * In 1999 a case was reported in which a 1p36 deletion in a fetus was detected when an amniocentesis was performed due to detection of multiple malformations on ultrasound
 * Another case was picked up prenatally because of the presence of elevated maternal serum alpha-fetoprotein (no abnormal sign seen on ultrasound).
 * Another was diagnosed prenatally because the mother was known to have a balanced translocation between the short arms of chromosome 1 and 20 that was picked up after their first child had inherited an unbalanced product. (no abnormal sign seen on ultrasound)

Medical Treatment

 * Seizures can usually be controlled with medication
 * Medical interventions and feeding therapy may be needed to manage feeding issues
 * Early Intervention for developmental delay
 * Surgery may be necessary to correct heart defects, cleft lip, cleft palate if present
 * A urine screen for neuroblastoma should be performed every 6 months
 * Physical examinations should involve palpating the abdomen for lumps which might be neuroblastomas
 * There are no clear indications on whether they should continue to be followed by a cardiologist or whether the cardiomyopathy is limited to a congenital form.

Psychosocial Issues

 * Initially parents may experience denial about how severe the developmental delay and mental retardation will be
 * Blaming of self or partner may occur
 * Stress of having a child with developmental delays and mental retardation
 * Stress associated with having a child with serious medical problems especially if they have heart malformations or seizures
 * Fear that the child might develop a neuroblastoma or seizures
 * Time commitment involved with early intervention services (OT, PT, speech therapy)

Patient Resources

 * Chromosome Deletion Outreach
 * MUMS


text:
Handbook of Genetic Counseling/1p36 Deletion Syndrome-2

1p36 Deletion Syndrome

Introduction

 * Mental retardation affects 2-3% of the population and chromosome abnormalities account for about 20% of cases
 * Improved techniques in cytogenetics (FISH) have helped to identify submicroscopic deletions at the cytogenetic level
 * Syndrome is characterized by distinct facial features, mental retardation, and delayed growth
 * This condition is likely a contiguous gene deletion syndrome
 * There is no uniform region of deletion but rather a spectrum of different deletion sizes with a common minimal region of deletion overlap
 * Genotype/phenotype comparisons can help researchers to start to define a region in which to search for candidate genes for specific features

Etiology of 1p36 deletion syndrome (monosomy 1p36)

 * Caused by deletion of the most distal (telomeric) light band of the short arm of chromosome 1
 * Most clinical manifestations are probably caused by the absence of one copy of a dose-sensitive gene
 * Patients with a 1p36 deletion have different sized pieces of the chromosome missing and may result in phenotype variability
 * Mechanism causing chromosome breakage is unknown
 * Severity of associated disorders varies, but the physical features are very similar
 * Degree of MR and ability to acquire complex speech is somewhat dependent on deletion size
 * Most deletions affect the chromosome inherited from the mother (68%), but there doesn't seem to be differences in the clinical manifestations based on whether the deletion is on the paternal or maternal chromosome.
 * Those with paternally derived deletions tend to have larger deletions than those with maternally derived deletions

Prevalence

 * Prevalence of this deletion is estimated to be 1 in 10,000 to as high as 1 in 5,000 (making it the most common terminal deletion)
 * Most cases result from sporadic deletions and are not inherited
 * 1p36 deletion syndrome is usually diagnosed through recognition of the symptoms and characteristics as well as lab testing.
 * This is done using high-resolution chromosome analysis or FISH with a chromosome 1-specific subtelomeric probe.
 * The deletion often doesn't show up clearly with standard cytogenetic banding techniques.

Characteristics

 * Children with 1p36 deletion syndrome are all unique individuals, but do have some common characteristics.
 * Distinct facial features including:
 * Large anterior fontanel (~100% of patients)
 * Small and pointed chin (~80%)
 * Flat nasal bridge (~65%)
 * Clinodactyly and/or short fifth finger (~64%)
 * Low-set ears, ear asymmetry (~59%)
 * Thickened ear helices (~53%)
 * Small head
 * Deep-set eyes (~50%)
 * Most patients have mental retardation
 * Most patients have delayed growth (~85%) and/or difficulty gaining weight
 * Some have difficulty with sucking and swallowing while others may not grow well even though they eat well.
 * Some older children may become obese.
 * Most young children with 1p36 deletion syndrome have delayed development.
 * They sit up, walk and talk later than typical children.
 * Speech is severely affected with many patients learning only a few words
 * Other medical problems:
 * Hypotony (which may explain delayed motor skills) (seen in ~92%)
 * Hearing loss (~56%)
 * Seizures (~72%)
 * KCNAB2 is a voltage-gated K+ channel beta-subunit gene that has been localized to 1p36 and thought to be associated with the epilepsy phenotype of 1p36
 * Eye/vision problems (~75%)
 * Hypothyroidism
 * Increased risk for neuroblastoma
 * Heart defects (which have included cardiomyopathy, ductus arteriosus, tetralogy of Fallot, VSD)
 * Orofacial clefting abnormalities
 * SKI, a proto-oncogene located at distal 1p36.3 has been found to be deleted in a number of patients tested and may contribute to facial clefting seen in this syndrome
 * SKI overexpression has suggested that the gene is involved in neural tube development and muscle differentiations.

Recurrence Risk for next pregnancy

 * The majority of patients with 1p36 deletion syndrome are isolated cases resulting from a de novo deletion. There have been reports of patients with 1p36 deletion syndrome whose parents have a balanced translocation.
 * Parents should be tested for chromosomal rearrangements because about 6% of parents with an affected child have a balanced translocation
 * Translocation increases the chances of having another child with a 1p36 deletion.
 * If no translocation is found the chances of having another child with a 1p36 deletion are very small

Prenatal Diagnosis

 * In 1999 a case was reported in which a 1p36 deletion in a fetus was detected when an amniocentesis was performed due to detection of multiple malformations on ultrasound
 * Another case was picked up prenatally because of the presence of elevated maternal serum alpha-fetoprotein (no abnormal sign seen on ultrasound)
 * Another was diagnosed prenatally because the mother was known to have a balanced translocation between the short arms of chromosome 1 and 20 that was picked up after their first child had inherited an unbalanced product. (no abnormal sign seen on ultrasound)

Medical Treatment

 * Seizures can usually be controlled with medication
 * Medical interventions and feeding therapy may be needed to manage feeding issues
 * Early Intervention for developmental delay
 * Surgery may be necessary to correct heart defects, cleft lip, cleft palate if present
 * Physical examinations should involve palpating the abdomen for lumps which might be neuroblastomas
 * There are no clear indications on whether they should continue to be followed by a cardiologist or whether the cardiomyopathy is limited to a congenital form.

Psychosocial Issues

 * Initially parents may experience denial about how severe the developmental delay and mental retardation will be
 * Blaming of self or partner may occur
 * Stress of having a child with developmental delays and mental retardation
 * Stress associated with having a child with serious medical problems especially if they have heart malformations or seizures
 * Time commitment involved with early intervention services (OT, PT, speech therapy)

Patient Resources

 * 1p36 Deletion Syndrome
 * Chromosome Deletion Outreach
 * MUMS


text:
Handbook of Genetic Counseling

This book is designed as an introduction to the discipline and practice of genetic counseling. The text provides an introduction to genetic counseling as a clinical practice and includes sample counseling outlines and letters for students of genetic counseling. Additional outline and letter examples are highly encouraged.

Introduction

 * Introduction
 * Counseling Methods
 * Counseling Theory

0-9

 * 1p36 Deletion Syndrome (outline 1)
 * 1p36 Deletion Syndrome (outline 2)
 * 18q Deletion Syndrome
 * 22q11 Deletion Syndrome

A

 * Abnormal Triple Screen and Family History of PKD
 * Achondroplasia (outline 1)
 * Achondroplasia (outline 2)
 * Acrofacial Dysostosis Syndrome
 * Advanced Maternal Age - Amniocentesis
 * Advanced Maternal Age - Chorionic Villus Sampling (CVS) (outline 1)
 * Advanced Maternal Age - Chorionic Villus Sampling (CVS) (outline 2)
 * Advanced Maternal Age - Chorionic Villus Sampling (CVS) (outline 3)
 * Allergies and Asthma
 * Alpha 1 Antitrypsin Deficiency
 * Alpha Thalassemia
 * Alport Syndrome
 * Amyotrophic Lateral Sclerosis
 * Androgen Insensitivity Syndrome
 * Anencephaly
 * Angelman Syndrome (outline 1)
 * Angelman Syndrome (outline 2)
 * AR Sensorineural Hearing Loss (DFNB1/Connexin 26)
 * Arthrogryposis
 * Autism (outline 1)
 * Autism (outline 2)
 * Autism (outline 3)

B

 * Balanced Robertsonian Translocation
 * Balanced Translocation
 * Bardet-Biedl Syndrome (outline 1)
 * Bardet-Biedl Syndrome (outline 2)
 * Beal's Syndrome
 * Becker Muscular Dystrophy
 * Beckwith-Wiedemann Syndrome
 * Beta-Thalassemia
 * Bloom Syndrome (outline 1)
 * Bloom Syndrome (outline 2)
 * Breast Cancer - Ashkenazi Jew

C

 * CADASIL
 * Canavan Disease: Heterozygote Screening
 * Cancer
 * Celiac Disease
 * Cerebral Palsy
 * CHARGE Association
 * Chondrodysplasia Punctata
 * Chorionic Villus Sampling (CVS)
 * Choroid Plexus Cysts on Ultrasound
 * Classical Myotonic Dystrophy
 * Cleft Lip and Palate
 * Cleft Lip - Isolated, Unilateral, Incomplete
 * Cleft Lip - Isolated, Unilateral, Incomplete (outline 1)
 * Cleft Lip - Isolated, Unilateral, Incomplete (outline 2)
 * Coffin-Lowry Syndrome
 * Colon Cancer Prophylactic Surgery
 * Colorectal Cancer Chemoprevention
 * Congenital Diaphragmatic Hernia
 * Cornelia de Lange Syndrome
 * Cowden Syndrome
 * Craniosynostosis (outline 1)
 * Craniosynostosis (outline 2)
 * Cri-du-chat syndrome - deletion 5p
 * Cystic Fibrosis Carrier Screening (outline 1)
 * Cystic Fibrosis Carrier Screening (outline 2)
 * Cystic Fibrosis - Prenatal Diagnosis (outline 1)
 * Cystic Fibrosis - Prenatal Diagnosis (outline 2)

D

 * Developmental Delay and Intellectual Disability (outline 1)
 * Developmental Delay and Intellectual Disability (outline 2)
 * Diabetes in Pregnancy
 * Diabetes Mellitus
 * Diabetic Embryopathy
 * Down Syndrome - Trisomy 21 (outline 1)
 * Down Syndrome - Trisomy 21 (outline 2)
 * Duchenne Muscular Dystrophy (outline 1)
 * Duchenne Muscular Dystrophy (outline 2)
 * Dysmorphic Features - Developmental Delay
 * Dysmorphic Features - Hypotonia

E

 * Echogenic Bowel
 * Ehlers-Danlos Syndrome
 * Ehlers-Danlos Syndrome (outline 2)
 * Ehlers-Danlos Syndrome (outline 3)
 * Epilepsy and Seizures
 * Ewing's Sarcoma

F

 * Fabry Disease
 * Familial Adenomatous Polyposis (outline 1)
 * Familial Adenomatous Polyposis (outline 2)
 * Fanconi Anemia
 * Fetal Alcohol Syndrome
 * Fetal Hydantoin Syndrome
 * Fetal Dilantin-Keppra Syndrome
 * Fetal Valproate Syndrome
 * FG Syndrome
 * FG Syndrome (outline 2)
 * First Trimester Screening
 * Fragile X Syndrome
 * Friedreich Ataxia
 * Frontonasal Dysplasia - Median Cleft Face Syndrome
 * Handbook of Genetic Counseling/FISH

G

 * Galactosemia (outline 1)
 * Galactosemia (outline 2)
 * Gastroschisis
 * Gaucher Disease (outline 1)
 * Gaucher Disease (outline 2)
 * Gaucher Disease (outline 3)
 * Genes and Chromosomes
 * Gorlin - Nevoid Basal Cell Carcinoma Syndrome

H

 * Hearing loss - Unknown Cause
 * Heart Defects - Isolated
 * Hemifacial Microsomia
 * Hemoglobin C
 * Hemoglobinopathy Screening and Hemoglobin D-Punjab
 * Hemophilia and Von Willebrand Disease
 * Hereditary Breast Cancer - BRCA1 and BRCA2
 * Hereditary Neuropathy with Liability to Pressure Palsies (HNPP) and Lobular Carcinoma In Situ (LCIS)
 * Hereditary Nonpolyposis Colorectal Cancer (HNPCC)
 * Holoprosencephaly
 * Huntington Disease
 * Hyper-extensibility
 * Hypoplasia - Agenesis of the Corpus Callosum
 * Hypotonia - Developmental Delay

I

 * IgA Nephropathy
 * Incontinence
 * Infertility

K

 * Keratoconus
 * Klinefelter Syndrome
 * Kartagener Syndrome

L

 * Lhermitte-Duclos disease
 * Lupron Exposure

M

 * Marfan Syndrome
 * Maternal Serum Triple Screen (outline 1)
 * Maternal Serum Triple Screen (outline 2)
 * McCune Albright Syndrome
 * Medium-chain acyl-coenzyme A dehydrogenase Deficiency
 * Microcephaly
 * Miller Syndrome
 * Mosaic trisomy 21 - Transient Myleoproliferative Syndrome
 * Mucopolysacharidosis (MPS)
 * Multiple Pregnancy Loss

N

 * Nager Syndrome
 * Neural Tube Defects
 * Neurofibromatosis - Type 1 (outline 1)
 * Neurofibromatosis - Type 1 (outline 2)
 * Neurofibromatosis - Type 1 (outline 2)
 * Neurofibromatosis - Type 2
 * Niemann-Pick Disease (outline 1)
 * Niemann-Pick Disease (outline 2)
 * Noonan Syndrome

O

 * Oculo-Auriculo-Vertebral Spectrum
 * Opitz BBB - G Syndrome
 * Oral-Facial-Digital Syndrome - Type 1
 * Osteogenesis Imperfecta (OI)
 * Osteosarcoma and Li-Fraumeni Syndrome
 * Ovarian Cancer

P

 * Pallister-Killian Syndrome "tetrasomy 12p"
 * Pancreatic Cancer
 * Partial Trisomy 11q (q14-q21)
 * Percutaneous Umbilical Blood Sampling (PUBS)
 * Phenylketonuria (PKU)
 * Pierre Robin Sequence - Cleft Palate
 * Pituitary Tumor
 * Polycystic Kidney Disease
 * Polydactyly and Syndactyly
 * Prader-Willi Syndrome - Prenatal
 * Prader-Willi Syndrome (outline 2)
 * Protein S Deficiency

R

 * Reciprocal Translocation
 * Renal Cell Carcinoma
 * Retinoblastoma
 * Rett Syndrome
 * Ring Chromosome 22
 * Robin Sequence
 * Russell Silver Syndrome

S

 * Smith-Magenis syndrome (SMS)
 * Sanfilippo syndrome
 * Scheie Syndrome
 * Seizure Medications
 * Septo-optic dysplasia
 * Short Chain Acyl-CoA Dehydrogenase (SCAD)
 * Short Stature
 * Sickle Cell Anemia
 * Smith-Lemli-Opitz Syndrome
 * Sotos Syndrome
 * Spina Bifida
 * Spinal Muscular Atrophy (SMA1)
 * Spontaneous Pregnancy Loss and X-chromosome Inactivation
 * Stickler Syndrome

T

 * Tamoxifen - Selective Estrogen Response Modifiers (SERMS)
 * Tay-Sachs Disease
 * Treacher Collins
 * Trisomy 13
 * Trisomy 13 - Advanced Maternal Age - Occupational Exposures
 * Trisomy 18
 * Tuberous Sclerosis (outline 1)
 * Tuberous Sclerosis (outline 2)
 * Turner Syndrome (outline 1)
 * Turner Syndrome (outline 2)

V

 * VATER Association
 * Van Der Woude syndrome
 * Velo-Cardio-Facial Syndrome (VCF)
 * Velopharyngeal Inadequacy (VPI)
 * Vitamin C Deficiency
 * Von Gierkes Disease (Glycogen Storage Disease Type I)
 * Von Hippel-Lindau Syndrome

W

 * Waardenburg Syndrome

X

 * XXX Syndrome

Z

 * Zellweger Syndrome

Useful Resources

 * Wikipedia's list of genetic disorders
 * Gene Clinics
 * OMIM Directory

Copyright
Much of the information for this book was originally located at http://www.genesoc.com/counseling2. That website is now defunct and the information and content from that site is being relocated here.

title: Handbook of Genetic Counseling


text:
User:Halavais~enwikibooks

Hi, I'm Alex. I'm fairly new here. I'm a prof of Communication and Informatics, and some of my students are putting together the seed of a Communication Theory text.

title: User:Halavais~enwikibooks


text:
Handbook of Genetic Counseling/18q Deletion Syndrome

18q Deletion Syndrome

Genetic Etiology

 * Caused by the deletion of the long arm of chromosome 18 (or, more often, a section of it)

Incidence and Carrier Frequency

 * The estimated frequency of the deletions syndromes of chromosome 18 (18p- & 18q-) is about 1/40,000 births. This would mean that about 100 babies per year in the United States are born with 18p- and 18q-.

 * 80% of cases occur due to de novo mutations; 10% of cases are due to a parental translocation; the remaining 10% are mosaic, usually resulting in a less severe phenotype

Clinical Features
This syndrome is variable in its severity. The symptoms usually correlate with the size of the deletion.

Key features:
 * Dysmyelination of the central nervous system (97%)
 * Hypotonia (79%)
 * Decreased or absent deep tendon reflexes (76%)
 * Short stature (61-77% of patients are below the fifth percentile)
 * Hearing impairment (70%)
 * Mental retardation IQ < 70 (68%)
 * Gait abnormalities (68%)
 * Ear anomalies
 * Narrow or atretic auditory canals (39-64%)
 * Prominent antihelix or antitragus (58%)
 * Low-set ears (8%)
 * Foot deformities (51-74%)
 * Club foot (21%)
 * Abnormal implantation of the second toe (21%)
 * Gap between first and second toe (3%)
 * Endocrine problems
 * IgA deficiency (30%)
 * Growth hormone deficiency (68%)
 * Facial dysmorphism
 * Microcephaly (53-56%)
 * "Carp-like" mouth (56%)
 * Microganthia (19%)
 * Midfacial hypoplasia (68%)
 * Slanted palpebral fissures (9%)
 * Hypertelorism (26%)
 * Epicanthic folds (29%)
 * Strabismus (20%)
 * Nystagmus (30%)
 * Pale optic discs (23%)
 * Broad nasal bridge (23%)
 * Cleft lip (9%)
 * Nodules at corner of mouth (6%)
 * Palate abnormality (30%)
 * Cleft palate (12%)
 * High arched (15%)
 * Bifid uvula (3%)
 * Abnormal genitalia
 * Females: dysplastic labia minora (35%)
 * Males (57%): cryptorchidism, hypospadias, micropenis, inguinal hernia (13%)
 * Thin hair (14%)
 * Widely spaced nipples (12%)
 * Hand anomalies
 * Tapered fingers (35%)
 * Proximal thumb (33-65%) with short first metacarpal
 * Transverse palmar creases (23%)
 * High whorl patterns on fingertips (36%) and high total finger ridge count
 * Fleshy tips of fingers (11%)
 * Clinodactyly (4%)
 * Skin dimples (23%)
 * Seizures (12%)
 * Genu varum (9%)
 * Brachycephaly (8%)
 * Umbilical hernia (7%)
 * Coloboma (4%)
 * Eczema (4%)
 * Inguinal hernia (4%)
 * Large protruding forehead (4%)
 * Dysplastic teeth (4%)
 * Delayed fontanel closure (4%)
 * Chorea (3%)
 * Low posterior hairline (3%)
 * Scoliosis (3%)
 * Strawberry birthmark on face (3%)
 * Short neck (3%)
 * Severe feeding problems (3%)

Age of onset, natural history, life span

 * Symptoms are apparent from birth in most cases
 * Natural history: Most patients have IQs between 40 and 85, normal IQ (100 or above) has also been reported. Short stature is common, as are various hearing and vision problems. Behavioral problems can occur, sometimes causing patients to exhibit autistic-like behaviors. These symptoms are variable, so a patient with a smaller deletion will have a milder phenotype than will a patient missing all of 18q.
 * Life span is variable, but may be decreased from the general population, depending upon severity of deletion and various congenital diseases or defects.

Testing
Diagnosis is confirmed by chromosome studies

Surveillance, management, and treatment options
Patients should be monitored by endocrinology, audiology, ophthalmology, genetics, neurology, orthopedics, immunology, physical therapy, occupational therapy, speech therapy, and Early Intervention.

Recent research has uncovered potential treatment for short stature and dysmyelination caused by 18q-. Growth hormone treatment has been shown to potentially increase IQ in children with 18q-. A 2005 study performed by Cody et al. showed that over a treatment period of 37 months an average nIQ increase of 17 pts, and an increase in height standard deviation score of 1.7. All but one of the children who tested within measureable range (>50) to the nonverbal IQ test had, at the end of the study, an IQ within normal range (i.e., >70).

Psychosocial issues
Guilt, fear, anxiety, anger, sadness, and disbelief are common emotions associated with this diagnosis. Parents may feel overwhelmed. Financial concerns, issues affecting family dynamics, and what care may be needed for the individual with 18q- are all things that should be addressed with parents.


text:
Handbook of Genetic Counseling/22q11 Deletion Syndrome

22q11 Deletion Syndrome (a.k.a. Velocardiofacial Syndrome (VCF), DiGeorge Syndrome)

Diagnosis
chromosome 22 (DGCR) deletion does not seem to correlate with severity of characteristics Characteristic Findings: and can be surgically repaired mouth to the esophagus pneumonia percentile in height narrow external auditory meati renal anomalies
 * Caused by a deletion of material from one copy of the long arm of
 * Submicroscopic deletion in DiGeorge Chromosomal Region
 * Chromosome banding may sometimes detect deletion
 * FISH testing detects deletion in 95% of affected individuals
 * Autosomal dominant inheritance
 * About 94% of patients have de novo mutation
 * Parents of affected individuals should have FISH testing
 * Offspring of affected individual have 50% chance of inheriting 22q11 deletion
 * Recurrence risk for siblings of affected individual is very small if FISH testing shows the parents do not have the deletion
 * Several genes are located within the DGCR
 * Some of these gene products have been identified
 * Cannot predict genotype-phenotype correlation because size of
 * Congenital heart disease
 * Found in about 74% of affected individuals
 * Usually conotruncal malformations
 * Teratology of Fallot
 * Interrupted aortic arch
 * Truncus arteriasis
 * Ventricular septal defect (VSD)
 * Conotruncal malformations identified in infancy/early childhood
 * Mild problems with the aorta may not be recognized
 * Palatal abnormalitites
 * Found in about 69% of affected individuals
 * Several types of abnormalities observed
 * Velopharyngeal incompetence (VPI)
 * Submucosal cleft palate
 * Visible cleft palate
 * Cleft lip and palate
 * Bifid uvulae
 * May be surgically repaired
 * May affect speech development
 * Speech therapy is recommended
 * Feeding difficulties
 * Found in about 30% of affected individuals
 * May be due to palate or heart problems
 * May also be caused by problems transporting food from the
 * Signs of feeding difficulty
 * Infants are irritable, gag, vomit, have a weak suck
 * Younger children find spoon feeding easier but have trouble drinking from a cup
 * Older children have difficulty with lumpy, crunchy foods
 * May be treated by teaching children better feeding practices
 * Immunodeficiency
 * Caused by small or missing thymus gland
 * Causes greatest number of problems in first year of life
 * Children may have frequent infections such as bronchitis or
 * As children grow older, T cell production improves
 * Hypoparathyroidism
 * Regulates calcium levels in bloodstream
 * Absence or underdevelopment leads to hypocalcemia
 * May cause tremors, seizures, muscle spasms, abnormal breathing, and abnormal heart rhythms
 * Diagnosed by a blood test
 * Treated with calcium supplements
 * Growth hormone deficiency
 * Approximately 41% of affected individuals are below the 5th
 * May be caused by abnormalities in formation of pituitary gland
 * In only about 1/10 of individuals with 22q11 deletion
 * Causes reduced levels of growth factors
 * Can be determined with a blood test
 * Treatment with injections of growth hormones
 * Characteristic Facial Features
 * Nose - bulbous nasal tip, prominent nasal root, nasal dimple
 * Ear - overfolded helices; cupped, microtic, and protuberant ears;
 * Eyes - hooding of upper or lower lid, ptosis, epicanthal folds
 * Renal anomalies
 * Found in about 37% of affected individuals
 * Includes single kidney, echogenic kidney, small kidneys, and other
 * Juvenile rheumatiod arthiritis (JRA)
 * About 150 times more frequent than in general population
 * Age of onset is 17 months to 5 years
 * Developmental difficulties
 * Found in 70-90% of affected individuals
 * Development of motor skills
 * Due to problems with muscle strength and coordination
 * Often delayed in sitting, crawling, walking
 * May be helped by physical therapy
 * Learning
 * Typically have slower learning rate
 * Follow same learning sequence as other children but at slower pace
 * Often have strong verbal skills but weaker math skills
 * May have difficulty paying attention
 * Early diagnosis and intervention important
 * May require learning support
 * Speech and language
 * Verbal speech usually does not develop until 2-3 years
 * May also have difficulty in formation of sounds
 * Palatal problems often lead speech problems
 * Early intervention by speech and language pathologist is important
 * Behavioral difficulties
 * About 40% of affected individuals develop psychiatric illness
 * Depression
 * Anxiety
 * Schizophrenia
 * Bipolar disorders
 * May be evident as tantrums and mood swings in childhood
 * Social skills training and counseling may be necessary

Resources

 * Cincinnati Velocardiofacial Support Group
 * Teresa Paul
 * 9327 Bluewing Terrace
 * Cincinnati, Ohio 45236
 * Email: MOTHERTP@aol.com

 * Velo-Cardio-Facial Syndrome Education Foundation
 * Jacobson hall Room 707
 * University Hospital
 * 750 East AdamsStreet
 * Syracuse, NY 13210
 * Phone: 315-464-6590
 * Email: vcfsef@hscsyr.edu
 * Web:

 * International DiGeorge/VCF Support Network
 * c/o Family Vioces of New York
 * 461/2 Clinton Avenue
 * Cortland, NY 13045
 * Phone: 607-753-1621 (day) 607-753-1250 (evening)

 * Chromosome Deletion Outreach, Inc.
 * PO Box 724
 * Boca Raton, FL 33429-0724
 * Phone: 561-395-4252
 * Email: cdo@worldnet.att.net
 * Web:


text:
Water Resources Directory/Welcome

Welcome! You are invited to use and especially to help write the Water Resources Directory.

Contributors to the Directory are acknowledged and listed by section.

Instructions for contributing to the Directory are provided.

title: Water Resources Directory/Welcome


text:
Communication Systems/Amplitude Modulation

Amplitude modulation is one of the earliest radio modulation techniques. The receivers used to listen to AM-DSB-C are perhaps the simplest receivers of any radio modulation technique; which may be why that version of amplitude modulation is still widely used today. By the end of this module, you will know the most popular versions of amplitude modulation, some popular AM modulation circuits, and some popular AM demodulation circuits.

Amplitude Modulation
Amplitude modulation (AM) occurs when the amplitude of a carrier wave is modulated, to correspond to a source signal. In AM, we have an equation that looks like this:

 * $$A_{signal}(t) = A(t) \sin (\omega t)$$

We can also see that the phase of this wave is irrelevant, and does not change (so we don't even include it in the equation).

AM Double-Sideband (AM-DSB for short) can be broken into two different, distinct types: Carrier, and Suppressed Carrier varieties (AM-DSB-C and AM-DSB-SC, for short, respectively). This page will talk about both varieties, and will discuss the similarities and differences of each.
 * [[Image:Amfm2.gif|left|thumb]]

Modulation Index
Amplitude modulation requires a high frequency constant carrier and a low frequency modulation signal.

 * A wave carrier is of the form $$e_c = E_c \cos \left( {\omega _c t} \right)$$

 * A wave modulation signal is of the form $$ e_m = E_m \cos \left( {\omega _m t} \right)$$

Notice that the amplitude of the high frequency carrier takes on the shape of the lower frequency modulation signal, forming what is called a modulation envelope.

 * [[Image:Am_envelope.jpg|left|thumb]]

The modulation index is defined as the ratio of the modulation signal amplitude to the carrier amplitude.

 * $$ m_{am} = \frac$$ where $$ 0 \le m_{am}  \le 1$$

The overall signal can be described by:

 * $$ e_{am} = \left( {E_c  + E_m \cos \left( {\omega _m t} \right)} \right)\cos \left( {\omega _c t} \right)$$

More commonly, the carrier amplitude is normalized to one and the am equation is written as:

 * $$ e_{am} = \left( {1 + m_{am} \cos \left( {\omega _m t} \right)} \right)\cos \left( {\omega _c t} \right)$$

 * In most experienced author books this expression is simply written as:

 * $$ e = \left( {1 + m\cos \omega _m t} \right)\cos \omega _c t$$

 * If the modulation index is zero ($$ m_{am} = 0$$) the signal is simply a constant amplitude carrier.

 * If the modulation index is 1 ($$ m_{am} = 1$$), the resultant waveform has maximum or 100% amplitude modulation.

 * [[Image:AM signals.svg|left|thumb]]

Sidebands
Expanding the normalized AM equation:

 * $$ e = \left( {1 + m\sin \omega _m t} \right)\sin \omega _c t$$

we obtain:

 * $$ e = \sin \omega _c t + \frac{m}{2}\cos \left( {\omega _c - \omega _m } \right)t - \frac{m}{2}\cos \left( {\omega _c  + \omega _m } \right)t$$

where:

 * $$\sin \omega _c t$$ represents the carrier

 * $$\frac{m}{2}\cos \left( {\omega _c - \omega _m } \right)t$$ represents the lower sideband

 * $$\frac{m}{2}\cos \left( {\omega _c + \omega _m } \right)t$$ represents the upper sideband

The sidebands occupies on the both sides of the center frequency. They are the sum and difference frequencies of the carrier and modulation signals. In the above example, they are just single frequencies, but normally the baseband modulation signal is a range of frequencies and hence two bands are formed.

AM Modulator
The standard amplitude modulation equation is:

 * $$e_{am} = \left( {1 + m\sin \omega _m t} \right)\sin \omega _c t$$

From this we notice that AM involves a multiplication process. There are several ways to perform this function electronically. The simplest method uses a switch.

Switching Modulators
Switching modulators can be placed into two categories: unipolar and bipolar.

Bipolar Switching Modulator
The bipolar switch is the easiest to visualize. Note that an AM waveform appears to consist of a low frequency dc signal whose polarity is reversing at a carrier rate.

 * [[Image:Bipolar_modulator_waveform.gif|left|thumb]]

The AM signal can be created by multiplying a dc modulation signal by

 * This seems complicated but, if the square wave switching function has a 50% duty cycle, this simplifies to:

 * $$F\left\{ {f\left( t \right)} \right\} = \frac{4}{\pi }\sum\limits_{n = 1,3,5...}^\infty {\frac{1}{n}} \cos \left( {\frac{T}} \right)$$

 * This tells us that the square wave is actually composed of a series of cosines (phase shifted sines) at odd multiples of the fundamental switching frequency. Therefore, using this signal to multiply the baseband signal results in AM signals being generated at each of the odd harmonics of the switching (carrier) frequencies. Since the amplitude of the harmonics decreases rapidly, this technique is practical for only the first few harmonics, and produces an enormous amount of unwanted signals (noise).

 * [[Image:Switching_mod_spectrum.gif|left|thumb]]

 * A band pass filter can be used to select any one of the AM signals. The number of different output frequencies can be significantly reduced if the multiplier accepts sinewaves at the carrier input.

 * Removing the DC component from the input eliminates the carrier signal and creates DSBSC modulation.

Physically this is done by reversing the signal leads:

 * [[Image:Switching_modulator.gif|left|thumb]]

The process of reversing the polarity of a signal is easily accomplished by placing two switch pairs in the output of a differential amplifier. The Mc1496 Balanced Modulator is an example of such a device.

 * [[Image:Transistor_switching_modulator.gif|left|thumb]]

Unipolar Switching Modulator
As previously mentioned, an AM signal can be created by multiplying a dc modulation signal by 0 & 1.

 * [[Image:Pulse.gif|left|thumb]]

 * The spectrum of this signal is defined by:

 * $$F\left\{ {f\left( t \right)} \right\} = \frac{1}{2} + \sum\limits_{n = 1}^\infty {\frac{2}\sin \left( {\frac{2}} \right)} \cos \left( {\frac{T}} \right)$$

Physically this is done by turning the modulation signal on and off at the carrier rate:

 * [[Image:Gated_carrier.gif|left|thumb]]

A high amplitude carrier can be used to turn a diode on and off. A dc bias is placed on the modulation signal to make certain that only the carrier (not the modulation signal) can reverse bias the diode.

 * [[Image:Gated_carrier_circuit.gif|left|thumb]]
 * [[Image:Unipolar_mod_waveform.gif|left|thumb]]

It may not seem obvious, but the output of this circuit contains a series of AM signals. A bandpass filter is needed to extract the desired one. Normally it is the 1st or 3rd harmonic of the fundamental. (The 1st harmonic is the fundamental.)

Collector Modulator
The diode switching modulator is incapable of producing high power signals since it is a passive device. A transistor can be used to overcome this limitation. A collector modulator is used for high level modulation.

 * [[Image:Collector_modulator.gif|left|thumb]]

Square Law Modulator
The voltage-current relationship of a diode is nonlinear near the knee and is of the form:

 * $$i\left( t \right) = av\left( t \right) + bv^2 \left( t \right)$$

 * The coefficient a and b are constants associated with the particular diode.

 * [[Image:Diode_curve.gif|left|thumb]]

Amplitude modulation occurs if the diode is kept in the square law region when signals combine.

 * [[Image:Square_law_modulator.gif|left|thumb]]

 * Let the injected signals be of the form:

 * $$k = {\rm{ dc}}\;{\rm{bias}}$$

 * $$e_m = E_m \sin \omega _m t = {\rm{modulation}}\;{\rm{signal}}$$

 * $$e_c = E_c \sin \omega _c t = {\rm{carrier}}\;{\rm{signal}}$$

 * The voltage applied across the diode and resistor is given by:

 * $$v\left( t \right) = k + e_m + e_c $$

 * The current in the diode and hence in the resistor is given by:

 * $$i\left( t \right) = a\left( {k + e_m + e_c } \right) + b\left( {k + e_m  + e_c } \right)^2 $$

 * Which expands to:

 * $$i\left( t \right) = \underbrace {k\left( {a + bk} \right)}_ + \underbrace {\left( {a + 2bk} \right)e_m }_{{\rm{original}}\;{\rm{modulating}}\;{\rm{signal}}} + \underbrace {\left( {a + 2bk} \right)e_c }_ + \underbrace {2be_m e_c }_{{\rm{2}}\;{\rm{sidebands}}} + \underbrace {be_m^2 }_{{\rm{2}}\;{\rm{x}}\;{\rm{modulating}}\;{\rm{frequency}}} + \underbrace {be_c^2 }_{{\rm{2}}\;{\rm{x}}\;{\rm{carrier}}\;{\rm{frequency}}}$$

Modulation Index Measurement
It is sometimes difficult to determine the modulation index, particularly for complex signals. However, it is relatively easy to determine it by critical observation.

There are two practical methods to derive the modulation index:
 * 1) By representing an AM wave as it is in time domain.(using maxima - minima terms.)
 * 2) By Trapezoidal method.
 * [[Image:Am_modulation_setup.gif|left|thumb]]
 * [[Image:Am_modulation_setup.gif|left|thumb]]

The trapezoidal oscilloscope display can be used to determine the modulation index.

 * [[Image:Trapazoidal_display.gif|left|thumb]]

 * AM modulation index: $$m = \frac$$

The trapezoidal display makes it possible to quickly recognize certain types of problems, which would reduce the AM signal quality.

 * [[Image:Trapezoidal_displays.gif|left|thumb]]

The highest authorized carrier power for AM broadcast in the US is 50 kilowatts, although directional stations are permitted 52.65 kilowatts to compensate for losses in the phasing system. The ERP can be much higher

C-QUAM
The basic idea behind the C-Quam modulator is actually quite simple. The output stage is an ordinary AM modulator however; the carrier signal has been replaced by an amplitude limited vector modulator. Therefore, the limiter output is really a phase-modulated signal.

 * [[Image:C-QUAM_modulator.gif|left|thumb]]

A standard AM receiver will detect the amplitude variations as L+R. A stereo receiver will also detect the phase variations and to extract L-R. It will then process these signals to separate the left and right channels.

To enable the stereo decoder, a 25 Hz pilot tone is added to the L-R channel.

AM Receivers
The most common receivers in use today are the super heterodyne type. They consist of:

 * Antenna
 * RF amplifier
 * Local Oscillator and Mixer
 * IF Section
 * Detector and Amplifier

The need for these subsystems can be seen when one considers the much simpler and inadequate TRF or tuned radio frequency amplifier.

TRF Amplifier
It is possible to design an RF amplifier to accept only a narrow range of frequencies, such as one radio station on the AM band.

 * [[Image:TRF_amplifier.gif|left|thumb]]

By adjusting the center frequency of the tuned circuit, all other input signals can be excluded.

 * [[Image:Channel_selection.gif|left|thumb]]

The AM band ranges from about 500 kHz to 1600 kHz. Each station requires 10 kHz of this spectrum, although the baseband signal is only 5 kHz.

Recall that for a tuned circuit: $$Q = \frac{B}$$. The center or resonant frequency in an RLC network is most often adjusted by varying the capacitor value. However, the Q remains approximately constant as the center frequency is adjusted. This suggests that as the bandwidth varies as the circuit is tuned.

 * For example, the Q required at the lower end of the AM band to select only one radio station would be approximately:

 * $$Q = \frac{B} = \frac = 50$$

 * As the tuned circuit is adjusted to the higher end of the AM band, the resulting bandwidth is:

 * $$B = \frac{Q} = \frac = 30\;kHz$$

A bandwidth this high could conceivably pass three adjacent stations, thus making meaningful reception impossible.

To prevent this, the incoming RF signal is heterodyned to a fixed IF or intermediate frequency and passed through a constant bandwidth circuit.

Superheterodyne Receiver

 * [[Image:Heterodyne.gif|left|thumb]]

The RF amplifier boosts the RF signal into the mixer. It has broad tuning and amplifies not just one RF station, but many of them simultaneously. It also amplifies any input noise and even contributes some of its own.

The other mixer input is a high frequency sine wave created by a local oscillator. In AM receivers, it is always 455 kHz above the desired station carrier frequency. An ideal mixer will combine the incoming carrier with the local oscillator to create sum and difference frequencies. .

A real mixer combines two signals and creates a host of new frequencies:

 * • A dc level
 * • The original two frequencies
 * • The sum and difference of the two input frequencies
 * • Harmonics of the two input frequencies
 * • Sums and differences of all of the harmonics

Since the RF amplifier passes several radio stations at once, the mixer output can be very complex. However, the only signal of real interest is the difference between the desired station carrier frequency and the local oscillator frequency. This difference frequency, also called the IF (intermediate frequency) will alway be 455 kHz. By passing this through a 10 kHz BPF (band pass filter) centered at 455 kHz, the bulk of the unwanted signals can be eliminated.

Local Oscillator Frequency
Since the mixer generates sum and difference frequencies, it is possible to generate the 455 kHz IF signal if the local oscillator is either above or below the IF. The inevitable question is which is preferable.

 * Case I The local Oscillator is above the IF. This would require that the oscillator tune from (500 + 455) kHz to (1600 + 455) kHz or approximately 1 to 2 MHz. It is normally the capacitor in a tuned RLC circuit, which is varied to adjust the center frequency while the inductor is left fixed.

 * Since $$f_c = \frac{1}$$

 * solving for C we obtain $$C = \frac{1}$$

 * When the tuning frequency is a maximum, the tuning capacitor is a minimum and vice versa. Since we know the range of frequencies to be created, we can deduce the range of capacitance required.

 * $$\frac = \frac = \left( {\frac} \right)^2 = 4$$

Making a capacitor with a 4:1 value change is well within the realm of possibility.

 * Case II The local Oscillator is below the IF. This would require that the oscillator tune from (500 - 455) kHz to (1600 - 455) kHz or approximately 45 kHz to 1145 kHz, in which case:

 * $$\frac = \left( {\frac} \right)^2 \approx 648$$

It is not practical to make a tunable capacitor with this type of range. Therefore the local oscillator in a standard AM receiver is above the radio band.

Image Frequency
Just as there are two oscillator frequencies, which can create the same IF, two different station frequencies can create the IF. The undesired station frequency is known as the image frequency.

 * [[Image:Image_frequency.gif|left|thumb]]

If any circuit in the radio front end exhibits non-linearities, there is a possibility that other combinations may create the intermediate frequency. Once the image frequency is in the mixer, there is no way to remove it since it is now heterodyned into the same IF band as the desired station.

AM Detection
There are two basic type of AM detection, coherent and non-coherent. Of these two, the non-coherent is the simpler method.

 * Non-coherent detection does not rely on regenerating the carrier signal. The information or modulation envelope can be removed or detected by a diode followed by an audio filter.
 * Coherent detection relies on regenerating the carrier and mixing it with the AM signal. This creates sum and difference frequencies. The difference frequency corresponds to the original modulation signal.

Both of these detection techniques have certain drawbacks. Consequently, most radio receivers use a combination of both.

Envelope Detector

 * [[Image:Envelope_detector.gif|left|thumb]]

When trying to demodulate an AM signal, it seems like good sense that only the amplitude of the signal needs to be examined. By only examining the amplitude of the signal at any given time, we can remove the carrier signal from our considerations, and we can examine the original signal. Luckily, we have a tool in our toolbox that we can use to examine the amplitude of a signal: The Envelope Detector.

An envelope detector is simply a half wave rectifier followed by a low pass filter. In the case of commercial AM radio receivers, the detector is placed after the IF section. The carrier at this point is 455 kHz while the maximum envelope frequency is only 5 kHz. Since the ripple component is nearly 100 times the frequency of the highest baseband signal and does not pass through any subsequent audio amplifiers.

 * An AM signal where the carrier frequency is only 10 times the envelope frequency would have considerable ripple:

 * [[Image:Exagerated_am_ripple.gif|left|thumb]]

Synchronous Detector
In a synchronous or coherent detector, the incoming AM signal is mixed with the original carrier frequency.

 * [[Image:Synchronous_detector.gif|left|thumb]]

If you think this looks suspiciously like a mixer, you are absolutely right! A synchronous detector is one where the difference frequency between the two inputs is zero Hz. Of in other words, the two input frequencies are the same. Let's check the math.

Recall that the AM input is mathematically defined by:

 * $$e_{am} = \underbrace {\sin \omega _c t}_ + \underbrace {\frac{m}{2}\sin \left( {\omega _c  - \omega _m } \right)t}_{{\rm{Lower}}\;{\rm{Sideband}}} - \underbrace {\frac{m}{2}\sin \left( {\omega _c  + \omega _m } \right)t}_{{\rm{Upper}}\;{\rm{Sideband}}}$$

 * At the multiplier output, we obtain:

 * $${\rm{mixer}}\;{\rm{out =  }}e_{am}  \times \sin \omega _c t = \underbrace { - \frac{m}{2}\sin \omega _m t}_{{\rm{Original}}\;{\rm{Modulation}}\;{\rm{Signal}}}\underbrace { - \frac{1}{2}\sin 2\omega _c t - \frac{m}{4}\sin \left( {2\omega _c  - \omega _m } \right)t + \frac{m}{4}\sin \left( {2\omega _c  + \omega _m } \right)t}_{{\rm{AM}}\;{\rm{signal}}\;{\rm{centered}}\;{\rm{at}}\;{\rm{2}}\;{\rm{times}}\;{\rm{the}}\;{\rm{carrier}}\;{\rm{frequency}}}$$

The high frequency component can be filtered off leaving only the original modulation signal.

This technique has one serious drawback. The problem is how to create the exact carrier frequency. If the frequency is not exact, the entire baseband signal will be shifted by the difference. A shift of only 50 Hz will make the human voice unrecognizable. It is possible to use a PLL (phase locked loop), but making one tunable for the entire AM band is not trivial.

As a result, most radio receivers use an oscillator to create a fixed intermediate frequency. This is then followed by an envelope detector or a fixed frequency PLL.

Squaring Detector
The squaring detector is also a synchronous or coherent detector. It avoids the problem of having to recreate the carrier by simply squaring the input signal. It essentially uses the AM signal itself as a sort of wideband carrier.

 * [[Image:Squaring_detector.gif|left|thumb]]

 * The output of the multiplier is the square of the input AM signal:

 * $${\left( {e_{am} } \right)^2 = \left( {\sin \omega _c t + \frac{m}{2}\cos \left( {\omega _c  - \omega _m } \right)t - \frac{m}{2}\cos \left( {\omega _c  + \omega _m } \right)t} \right)^2} $$

Since the input is being multiplied by the $${\sin \omega _c t}$$ component, one of the resulting difference terms is the original modulation signal. The principle difficulty with this approach is trying to create a linear, high frequency multiplier.

AM-DSB-SC
AM-DSB-SC is characterized by the following transmission equation:

 * $$v(t) = A s(t) \cos(2 \pi f_c t)$$

It is important to notice that s(t) can contain a negative value. AM-DSB-SC requires a coherent receiver, because the modulation data can go negative, and therefore the receiver needs to know that the signal is negative (and not just phase shifted). AM-DSB-SC systems are very susceptible to frequency shifting and phase shifting on the receiving end. In this equation, A is the transmission amplitude.

Double side band suppressed carrier modulation is simply AM without the broadcast carrier. Recall that the AM signal is defined by:

 * $$e_{am} = \left( {1 + m\sin \omega _m t} \right)\sin \omega _c t = \sin \omega _c t + \frac{2}\cos \left( {\omega _c  - \omega _m } \right)t - \frac{2}\cos \left( {\omega _c  + \omega _m } \right)t$$

 * The carrier term in the spectrum can be eliminated by removing the dc offset from the modulating signal:

 * $$e_{DSBSC} = m\sin \omega _m t\sin \omega _c t = \frac{2}\cos \left( {\omega _c  - \omega _m } \right)t - \frac{2}\cos \left( {\omega _c  + \omega _m } \right)t$$

Double Balanced Ring Modulator
One of the circuits which is capable of creating DSBSC is the double balance ring modulator.

 * [[Image:Ring_modulator.gif|left|thumb]]

If the carrier is large enough to cause the diodes to switch states, then the circuit acts like a diode switching modulator:

 * [[Image:Ring_modulator_2.gif|left|thumb]]

The modulation signal is inverted at the carrier rate. This is essentially multiplication by ±1. Since the transformers cannot pass dc, there is no term which when multiplied can create an output carrier. Since the diodes will switch equally well on either cycle, the modulation signal is effectively being multiplied by a 50% duty cycle square wave creating numerous DSBSC signals, each centered at an odd multiple of the carrier frequency. Bandpass filters are used to extract the frequency of interest.

Some IC balanced modulators use this technique, but use transistors instead of diodes to perform the switching.

Push Pull Square Law Balanced Modulator

 * [[Image:Push_pull_mod.gif|left|thumb]]

This circuit uses the same principles as the diode square law modulator. Since dc cannot pass through the transformer, it would be expected that there would be no output signal at the carrier frequency.

The drain current vs. gate-source voltage is of the form:

 * $$i_d = i_0  + av_{gs}  + v_{gs}^2 $$

 * The net drain current in the output transformer is given by:

 * $$i_{net} = i_{d1}  - i_{d2}  = i_0  + av_{gs1}  + bv_{gs1}^2  - \left( {i_0  + av_{gs2}  + bv_{gs2}^2 } \right)$$

 * $$i_{net} = a\left( {v_{gs1}  - v_{gs2} } \right) + b\left( {v_{gs1}  + v_{gs2} } \right)\left( {v_{gs1}  - v_{gs2} } \right)$$

 * By applying KVL around the gate loops we obtain:

 * $$v_{gs1} = \frac{2} + e_c \quad \quad \quad \quad v_{gs2}  =  - \frac{2} + e_c $$

 * Putting it all together we obtain:

 * $$i_{net} = a\left( {\frac{2} + e_c  + \frac{2} - e_c } \right) + b\left( {\frac{2} + e_c  - \frac{2} + e_c } \right)\left( {\frac{2} + e_c  + \frac{2} - e_c } \right)$$

 * $$i_{net} = ae_m  + 2be_c e_m $$

 * From this we note that the first term is the originating modulation signal and can easily be filtered off by a high pass filter. The second term is of the form:

 * $$\sin \omega _m t\sin \omega _c t = \frac{1}{2}\cos \left( {\omega _c - \omega _m } \right)t - \frac{1}{2}\cos \left( {\omega _c  + \omega _m } \right)t$$

 * which is AM DSBSC.

AM-DSB-C
In contrast to AM-DSB-SC is AM-DSB-C, which is categorized by the following equation:

 * $$v(t) = A [s(t) + c] \cos (2 \pi f_c t)$$

Where c is a positive term representing the carrier. If the term $$[s(t) + c]$$ is always non-negative, we can receive the AM-DSB-C signal non-coherently, using a simple envelope detector to remove the cosine term. The +c term is simply a constant DC signal and can be removed by using a blocking capacitor.

It is important to note that in AM-DSB-C systems, a large amount of power is wasted in the transmission sending a "boosted" carrier frequency. since the carrier contains no information, it is considered to be wasted energy. The advantage to this method is that it greatly simplifies the receiver design, since there is no need to generate a coherent carrier signal at the receiver. For this reason, this is the transmission method used in conventional AM radio.

AM-DSB-SC and AM-DSB-C both suffer in terms of bandwidth from the fact that they both send two identical (but reversed) frequency "lobes", or bands. These bands (the upper band and the lower band) are exactly mirror images of each other, and therefore contain identical information. Why can't we just cut one of them out, and save some bandwidth? The answer is that we can cut out one of the bands, but it isn't always a good idea. The technique of cutting out one of the sidebands is called Amplitude Modulation Single-Side-Band (AM-SSB). AM-SSB has a number of problems, but also some good aspects. A compromise between AM-SSB and the two AM-DSB methods is called Amplitude Modulation Vestigial-Side-Band (AM-VSB), which uses less bandwidth then the AM-DSB methods, but more than the AM-SSB.

Transmitter
A typical AM-DSB-C transmitter looks like this:

c   cos(...) |      | Signal >(+)>(X)> AM-DSB-C

which is a little more complicated than an AM-DSB-SC transmitter.

Receiver
An AM-DSB-C receiver is very simple:

AM-DSB-C >|Envelope Filter|>|Capacitor|> Signal

The capacitor blocks the DC component, and effectively removes the +c term.

AM-SSB
To send an AM-SSB signal, we need to remove one of the sidebands from an AM-DSB signal. This means that we need to pass the AM-DSB signal through a filter, to remove one of the sidebands. The filter, however, needs to be a very high order filter, because we need to have a very aggressive roll-off. One sideband needs to pass the filter almost completely unchanged, and the other sideband needs to be stopped completely at the filter.

To demodulate an AM-SSB signal, we need to perform the following steps:

 * 1) Low-pass filter, to remove noise
 * 2) Modulate the signal again by the carrier frequency
 * 3) Pass through another filter, to remove high-frequency components
 * 4) Amplify the signal, because the previous steps have attenuated it significantly.

AM-SSB is most efficient in terms of bandwidth, but there is a significant added cost involved in terms of more complicated hardware to send and receive this signal. For this reason, AM-SSB is rarely seen as being cost effective.

Single sideband is a form of AM with the carrier and one sideband removed. In normal AM broadcast, the transmitter is rated in terms of the carrier power. SSB transmitters attempt to eliminate the carrier and one of the sidebands. Therefore, transmitters are rated in PEP (peak envelope power).

 * $$PEP = \frac$$

 * With normal voice signals, an SSB transmitter outputs 1/4 to 1/3 PEP.

There are numerous variations of SSB:

 * SSB - Single sideband - amateur radio
 * SSSC - Single sideband suppressed carrier - a small pilot carrier is transmitted
 * ISB - Independent sideband - two separate sidebands with a suppressed carrier. Used in radio telephony.
 * VSB - Vestigial sideband - a partial sideband. Used in broadcast TV.
 * ACSSB - Amplitude companded SSB

There are several advantages of using SSB:

 * • More efficient spectrum utilization
 * • Less subject to selective fading
 * • More power can be placed in the intelligence signal
 * • 10 to 12 dB noise reduction due to bandwidth limiting

Filter Method
The simplest way to create SSB is to generate DSBSC and then use a bandpass filter to extract one of the sidebands.

 * [[Image:Filter_sideband.gif|left|thumb]]

This technique can be used at relatively low carrier frequencies. At high frequencies, the Q of the filter becomes unacceptably high. The required Q necessary to filter off one of the sidebands can be approximated by:

 * $$Q \approx \frac$$

 * where:

 * $$f_c = {\rm{ carrier}}\;{\rm{frequency}}$$
 * $$\Delta f = {\rm{ sideband}}\;{\rm{separation}}$$
 * $$S = {\rm{ sideband}}\;{\rm{suppression}}\;{\rm{(not}}\;{\rm{in}}\;{\rm{dB)}}$$

Several types of filters are used to suppress unwanted sidebands:

 * LC - Maximum Q = 200
 * Ceramic - Maximum Q = 2000
 * Mechanical - Maximum Q = 10,000
 * Crystal - Maximum Q = 50,000

In order to reduce the demands placed upon the filter, a double heterodyne technique can be used.

 * [[Image:SSB_double_heterodyne.gif|left|thumb]]

The first local oscillator has a relatively low frequency thus enabling the removal of one of the sidebands produced by the first mixer. The signal is then heterodyned a second time, creating another pair of sidebands. However, this time they are separated by a sufficiently large gap that one can be removed by the band limited power amplifier or antenna matching network.

 * Example

 * Observe the spectral distribution under the following conditions:

 * • Audio baseband = 100 HZ to 5 KHz
 * • LO1 = 100 kHz
 * • LO2 = 50 MHz

 * The spectral output of the first mixer is:

 * [[Image:First_mixer.gif]]

 * If the desired sideband suppression is 80 dB, the Q required to filter off one of the sidebands is approximately:

 * $$S = \log ^{ - 1} \left( {\frac} \right) = 10^4$$

 * $$Q \approx \frac = \frac = 12500$$

 * It is evident that a crystal filter would be needed to remove the unwanted sideband.

 * After the filter, only one sideband is left. In this example, we’ll retain the USB. The spectrum after the second mixer is:

 * [[Image:SSB modulator second mixer output.gif]]

 * The Q required to suppress one of the side bands by 80 dB is approximately:

 * $$Q \approx \frac = \frac = 6244$$

 * Thus, we note that the required Q drops in half.

This SSB filter technique is used in radiotelephone applications.

Phase Shift Method

 * [[Image:SSB_phase_shift.gif|left|thumb]]

The output from the top mixer is given by:

 * $$\sin \omega _m t\sin \omega _c t = \frac{1}{2}\cos \left( {\omega _c - \omega _m } \right)t - \frac{1}{2}\cos \left( {\omega _c  + \omega _m } \right)t$$

 * The output from the bottom mixer is given by:

 * $$\cos \omega _m t\cos \omega _c t = \frac{1}{2}\cos \left( {\omega _c - \omega _m } \right)t + \frac{1}{2}\cos \left( {\omega _c  + \omega _m } \right)t$$

 * The output of the sumer is:

 * $$\cos \left( {\omega _c - \omega _m } \right)t$$

 * which corresponds to the lower sideband.

The major difficulty with this technique is the need to provide a constant 90o phase shift over the entire input audio band. To overcome this obstacle, the Weaver or third method uses an audio sub carrier, which is phase shifted.

Weaver Method
The Weaver or ‘third’ method places the baseband signal on a low frequency quadrature carrier.

 * [[Image:SSB_Weaver.gif|left|thumb]]

This has the advantage of not requiring a broadband phase shifter however; the use of four mixers makes it awkward and seldom used.

 * [[Image:AM_waveforms.gif|left|thumb]]

SSB Transmitter
AM-SSB transmitters are a little more complicated: cos(...) | Signal >(X)>|Low-Pass Filter|> AM-SSB

The filter must be a very high order, for reasons explained in that chapter.

SSB Receiver
An AM-SSB receiver is a little bit complicated as well:

cos(...) | AM-SSB >(X)>|Low-Pass Filter|>|Amplifier|> Signal

This filter doesnt need to be a very high order, like the transmitter has.

These receivers require extremely stable oscillators, good adjacent channel selectivity, and typically use a double conversion technique. Envelope detectors cannot be used since the envelope varies at twice the frequency of the AM envelope.

Stable oscillators are needed since the detected signal is proportional to the difference between the untransmitted carrier and the instantaneous side band. A small shift of 50 Hz makes the received signal unusable.

SSB receivers typically use fixed frequency tuning rather than continuous tuning as found on most radios. Crystal oscillators are often used to select the fixed frequency channels.

AM-VSB
Single-sideband modulation works satisfactorily for an information-bearing signal (e.g.,

speech signal) with an energy gap centered around zero frequency. However, for the spectrally

efficient transmission of wideband signals, we have to look to a new method of modulation

for two reasons:

 * Typically, the spectra of wideband signals (exemplified by television video signals and

computer data) contain significant low frequencies, which make it impractical to use

SSB modulation.

 * The spectral characteristics of wideband data befit the use of DSB-SC. However, DSBSC

requires a transmission bandwidth equal to twice the message bandwidth, which

violates the bandwidth conservation requirement.

To overcome these two practical limitations, we need a compromise method of modulation

that lies somewhere between SSB and DSB-SC in its spectral characteristics. Vestigial sideband,

the remaining modulation scheme to be considered in this section, is that compromise

scheme.

Vestigial sideband (VSB) modulation distinguishes itself from SSB modulation in two

practical respects:

 * Instead of completely removing a sideband, a trace or vestige of that sideband is transmitted, hence, the name “vestigial sideband.”

 * Instead of transmitting the other sideband in full, almost the whole of this second band is also transmitted.

Transmitter
Here we will talk about an AM-VSB transmitter circuit.

Receiver
Here we will talk about an AM-VSB receiver circuit.


text: Template:RenderPNG

title: Template:RenderPNG


text:
Cookbook:Luciabullar (Scandinavian Saffron Buns)

| Holiday recipes

Lussekatter or luciabullar are Scandinavian saffron buns served on St. Lucia Day (13 December).

Ingredients

 * 2 packages (4½ tsp) active dry yeast
 * ¼ cup lukewarm water
 * ½ tsp crushed (¼ tsp powdered) saffron threads
 * ¾ cup (180 ml) half and half, lukewarm
 * ½ cup (120 g) melted butter
 * 2 eggs, beaten
 * ¾ cup (180 g) white granulated sugar
 * 1 tsp salt
 * 4–5 cups sifted all-purpose flour
 * Raisins to decorate

Procedure

 * 1) Combine the yeast and warm water.
 * 2) Mix saffron into the warm half and half and let stand.
 * 3) Combine the yeast and saffron mixtures. Mix in the melted butter, eggs, sugar, and salt.
 * 4) Mix half of flour into the wet mixture and beat until well-blended.
 * 5) Mix in additional flour until dough is smooth but not too firm. Knead on floured surface for ten minutes.
 * 6) Place dough in buttered bowl and let rise about 1½ hours or until doubled in volume.
 * 7) Divide the dough into multiple pieces. Roll each piece into a 7 inch-long snake, and form into an 'S' shape with the ends curled in. Place a raisin in each curl.
 * 8) Place buns on buttered sheet pan, cover, and let rise 45 minutes.
 * 9) Brush with beaten egg and bake at 375–400°F (190–200°C) for 10–15 minutes until golden and cooked through.

External link

 * Photos of baking saffron buns

Kokboken/Recept/Lussekatt


text:
Communication Systems/Pulse Amplitude Modulation

Definition
What is PAM? Pulse-Amplitude Modulation is "pulse shaping". Essentially, communications engineers realize that the shape of the pulse in the time domain can positively or negatively affect the characteristics of that pulse in the frequency domain. There is no one way to shape a pulse, there are all sorts of different pulse shapes that can be used, but in practice, there are only a few pulse shapes that are worth the effort. These chapters will discuss some of the common pulses, and will develop equations for working with any generic pulse.

Square Wave
The most logical way to transmit a digital signal is through a stream of pulses. One distinct pulse for a digital "1", and another distinct pulse for a digital "0". Intuitively, a square pulse will transmit this data, and there are a number of different ways to transmit the data using

The square wave is a basic choice for transmitting digital data because it is easy to transmit, and is generally easy to receive. If we take the fourier transform of a square wave, we get a sinc function. A sinc function is a never-ending function, which means that a square wave in the time domain has a very wide bandwidth. When using a square wave, there will always be a trade-off, because high-frequency components of the square wave will be attenuated by the channel, and the resultant waveform will be more prone to error on the other end.

Unipolar Square Wave
A unipolar square wave is a wave where a logical 1 is transmitted using a square pulse of height A. Then a logical 0 is transmitted with a 0 voltage.

Bipolar Square Wave
A bipolar square wave is a square wave where a 1 is transmitted with a pulse of height A/2, and a 0 is transmitted with a pulse of -A/2.

Other pulses
It turns out that simply by changing the shape of the pulse (changing it away from a square wave), we can create a signal with better properties: lower bandwidth, lower error rate, etc... This section will talk about a few different pulses.

Sinc
By the property of duality, however, we can see that if we have a sinc wave in the time domain, we will have a square-shape in the frequency domain. This is an interesting result, because it means that we can transmit a sinc shape with definite bandwidth bounds, and it can travel through a channel in its entirety without being attenuated, or losing any harmonics!

Comparison
Here we will show a basic comparison between square pulses and sinc pulses:

slew-rate-limited pulses
Most systems that use RS232, RS485, or high speed clocks use slew-rate-limited drivers. Some use driver chips with integrated slew-rate limiting; other systems use digital driver chips that put sharp square pulses on their output pins, then an external slew-rate-limiting resistor between that output pin and the rest of the system.

Raised-Cosine Rolloff
Sinc pulses use less bandwidth, but they are very susceptible to jitter. Conversely, Square pulses have a large bandwidth, but are very resistant to jitter. The decision seems hopeless, but the intrepid communications engineer will try to find a 3rd option. The 3rd option is called the "Raised-Cosine Rolloff" pulse, and has the best characteristics of each wave. Raised Cosine Rolloff (RCR) pulses are resistant to jitter, and at the same time have reasonably good bandwidth. Granted the bandwidth of an RCR pulse is wider than a sinc pulse, and the jitter resistance isn't as good as with a square wave, but this is a compromise, after all.

Binary symmetric pulses
A system uses binary symmetric pulses if it transmits only 2 kinds of pulse, s1 and s0, and s1(t) = -s0(t). In a symmetric case, our comparator circuits are very easy: If the correlator outputs a positive value, it's a binary 1. If it outputs a negative value, it's a binary 0.

Asymmetric Pulses
Asymmetric pulses are more difficult for many reasons:

 * 1) The threshold where the comparator should test the value may not be zero
 * 2) The correlation receiver needs to correlate two different signals.
 * 3) The different pulses may have different power, and they may be different susceptible to noise.

Asymmetric Correlation Receiver
When asymmetric pulses are used, the receiver system must actually employ 2 coherent optimal receivers, each one tuned to receive one of the pulses. When two coherent optimal receivers are used, the receiver that is outputting the highest voltage value at the end of time T has received it's pulse.

''... why not employ only 1 coherent optimal receiver, tuned to receiver neither s0 nor s1, but instead tuned to receive the difference (s1 - s0) ? ...''

Some PAM systems, such as Ethernet 100BASE-T2, use PAM-5 ...


text:
The Computer Revolution/The Internet Revolution

= Timeline =

The development of the internet is filled with currents and counter-currents, repression, dissension and rebellion. It isn't a simple story of success after success but rather includes missed opportunities, projects that were feasible and still haven't been achieved, and futile efforts, projects that were repeatedly attempted despite being provably impossible. The history of the internet is filled with individual events, none of them meaningful without context. This is the story of the internet, not one of heroic god figures walking upon the Earth but of human beings who dream and act upon those dreams.

Recurring threads to be coded:

 * discussion networks; human-nets
 * archives / engines
 * protocols / technologies
 * multimedia

The 80's

 * 1980 - Making use of Unix v7's UUCP facility, A News sees the birth of Usenet between UNC and Duke universities. At this time, the ARPANET is a tightly-controlled self-contained network under the regulation of the US Defense Communications Agency. In contrast, the UUCPnet is quickly conceived of as a self-regulated public network mostly kept hidden from management. After all, management does have to approve hundreds of 1980 dollars in monthly phone bills and possibly several thousand in initial equipment expenditures.
 * 1980 - Mark Horton feeds the human-nets ARPANET mailing list into the FA.Human-nets Usenet newsgroup. Human-nets discusses the implications of a worldwide computer communications network, usually referred to as WorldNet. The connection is strictly one-way but the ability to eavesdrop on ARPANET discussions provides critical incentive to join Usenet.
 * 1981 - UCB's ucbvax is used as a gateway between the ARPANET and Usenet for various mailing lists. This initial breach in the iron curtain is precarious. MIT loses several months fighting legal battles after being threatened off of the ARPANET for serving as a gateway from Usenet. It remains impossible for a UUCPnet user to send email to an ARPANET user.
 * 1982 - The word "cyberspace" is coined by William Gibson in his novelette "Burning Chrome" and will subsequently be popularized in his novel "Neuromancer" (1984).
 * 1983 - Usenet gets its first cross-Atlantic link using a dialup modem connecting DEC's decvax and Mathematisch Centrum's mcvax in the Netherlands.
 * 1983 - TCP/IP replaces the ARPANET's NCP. It will not be adopted in Europe where OSI models are considered sacred despite the hatred of the users they are imposed on.
 * 1984 April 1 - Piet Beertema of MC forges a news article from President Chernenko of the USSR announcing the Soviet Union's entry on the Usenet. Some people caught in the hoax respond that it was in bad taste to raise their hopes of much improved US-USSR relations. The Pentagon will investigate "how to deal with" this breach in national security, the USSR's entry on Usenet. The USA maintains an embargo of advanced computing technology.
 * 1984 June - FidoNet is created over version 7 of Fido.
 * 1985 April - The WELL (originally Whole Earth 'Lectronic Link) goes online.
 * 1987 May - John Gilmore, Brian Reid and Gordon Moffett unilaterally create the alt. hierarchy of Usenet, starting with alt.drugs.
 * 1988 April - Gene Spafford unilaterally refuses to create soc.sex, prompting the creation of alt.sex and alt.rock-n-roll. It will be some time before anyone realizes that alt. newsgroups are immortal.
 * 1988 August - The first IRC network, EFnet, goes online.
 * 1988 November 2 - Robert Morris unleashes the first ever internet worm
 * 1988 November 17 - EUnet gets its first open transatlantic connection with the internet.
 * 1989 Tim Berners-Lee created HTML as everyone knows and loathes. He is credited with inventing the web, despite the fact that he did not.

The 90's

 * 1990 July - Mitch Kapor, John Perry Barlow, and John Gilmore found the Electronic Frontier Foundation to protect civil liberties on the internet in response to the US Secret Service's seizure of Steve Jackson Games' computers (no charges were filed, the company was nearly ruined).
 * 1990 October - Col Needham releases shell scripts that allow searching of rec.arts.movies' datafiles. This will eventually become the IMDB (Internet Movie Database).
 * 1991 - MP3 is defined and standardized.
 * 1991 - Gopher is released.
 * 1992 - The Lynx browser is released to work over Gopher and native markup.
 * 1993 - The US government announces the Clipper chip as a means to promote encryption breakable by the government. The proposal is roundly condemned.
 * 1993 Mosaic version 1.0 is released. It was described as "the killer application of the 1990s" because it was the first program to provide a slick multimedia graphical user interface to the Internet.
 * 1994 January - Yahoo.com is founded.
 * 1994 July 7 - The Fraunhofer Society released the first MP3 encoder called l3enc.
 * 1994 December - Netscape releases Netscape Navigator 1.0
 * 1995 - Amazon.com goes online.
 * 1995 - Deja News' searchable Usenet archive goes online.
 * 1995 September - Ebay goes online out of Pierre Omidyar's living room.
 * 1995 August - Infoseek goes online as a directory service, available on a paid subscription basis.
 * 1995 December - DEC labs' Altavista research project goes online, available for free.
 * 1996 - The Internet Archive is founded. The Wayback Machine's archive dates back to 1995.
 * 1996 November - ICQ was introduced by Mirabilis, an Israeli start-up company. The first general instant messenger for non-UNIX computers.
 * 1996 December - Macromedia Flash version 1.0 is released. (Source: The History of Flash)
 * 1997 - Winamp is released.
 * 1997 September - Stanford University's Google research project goes online
 * 1998 January - the Drudge Report initiates the Clinton sex scandal
 * 1998 - PHP version 3.0 is released. The first version that closely resembles PHP as we know it today
 * 1998 - Audiogalaxy started.
 * 1999 - Napster is released. It was the first peer-to-peer music sharing service. It led audiogalaxy to create its famed P2P satellite.

The 00's

 * 2001 February - Google acquires Deja's Usenet archive
 * 2004 February - Facebook is founded.

= Special Topics =

Killer applications
A killer application is an application which justifies in everyone's minds their acquisition of an entire computer. The first killer internet application was email. The second was the web. The third was peer to peer file sharing.

Eras
The internet has experienced distinct eras, rarely associated with any particular event. The earliest era was one of shared computing. This was the era of shell accounts, before home computers, and SLIP/PPP over phone lines became ubiquitous.

The beginning of the new era coincided with the rise of the graphical web browser. Before presentation was offloaded to home computers using SLIP/PPP dialup, it simply wasn't feasible to allow each user to run a graphical application on the central servers.

(Note that this new era was just a new paradigm and hardly an advance in every way. With the demise of shell accounts, it is no longer possible to search Usenet articles without downloading their contents to one's home computer. This was a significant problem before broadband.)

This third era we are in is simply the broadband era. Whether it is from the cable, phone or electric utility company, broadband provides enough network bandwidth that users make use of the network in a qualitatively different way (music and video swapping, and Voice over IP).

The fourth era just now beginning is one of not wireless but mobile networking. The hallmarks of this era are MP3 players, cell phones and to some extent PDAs. Electronic paper, if it ever actually gets built, would be symbolize the peak of this era.

The fifth era being planned in research labs like Xerox PARC's is one of ubiquitous computing and will require that the current transition from personal computers back to social computers be complete.

Peer to peer
The original peer to peer application was Usenet. Almost from the first, Usenet was conceived as a way of sharing files (articles) and directories (newsgroups) between peers. Further, Usenet has a long history of being used to distribute movies, pictures, music and software. Software in particular has been distributed on Usenet from its very beginning and was one of the reasons given to management to justify the enormous expense of joining Usenet. When Napster came along in 1999, it was structured differently from Usenet for the simple reason of the very different demands of music users.

In particular, music users were unwilling, and quite unable, to carry the entire load of every other music users' library. But more importantly, analogues to newsgroups were deemed unacceptable from the first. With no way to structure or fraction users' libraries of music, being able to search for individual objects (songs or albums) and keeping track of individual users became key requirements. These requirements served as constraints that naturally enough gave rise to very different architectures from Usenet's.

Web-based applications
Web-based applications follow a venerable history of running a low-availability service on top of a high-availability service in order to increase the availability of the former.

In the 90s, FTP and even Web services were available through email since email was by far the most widely available service. In fact, even some Usenet newsgroups were available through email through the intermediary of newsgroup to mailing list gateways. The greatest problem involved providing anonymous email services over email. Remailers largely died off after anon.penet.fi was forced to hand over users' information by the Finnish government at the behest of the Church of Scientology.

In that era, PPP and SLIP were hardly ubiquitous and not everyone had a shell account at their ISP, if the ISP even provided shell accounts. Nowadays, the most widely available service is the web and so other services run on top of it. With this history behind it, the minor innovation of putting services on the web hardly merits the appellation of an innovation.

 * email
 * newsgroups, of both the Usenet and non- varieties
 * wikis
 * blogs
 * bookmarks

Privacy Protection: Europe vs Anglo-American attitudes
ECHELON is an international electronic espionage network that aims to tap into all communications lines. ECHELON is maintained by the Anglo-American (USA, Canada, UK and Australia) governments and is unaccountable to anyone else. The Anglo-American governments are routinely accused of spying on their own citizens using ECHELON.

While the European Union is routinely betrayed by the United Kingdom (which supplies up to the minute information of confidential meetings to the USA), the EU has seen enough threat in ECHELON to fund the development of unbreakable quantum cryptography technology in 2004.

It is against this broader background that any issues of privacy protection must be evaluated.

The Anglo-American governments' attitudes to privacy is roughly summed up as 'you don't have any'. In 1993, the US government introduced the Clipper chip in order to be able to break into citizens' cryptographically secured communications. In 2000, the UK government passed an Act enabling police to demand a citizen's cryptographic keys without a warrant.

The response of Anglo-American governments towards corporate intrusions of privacy is characterized by appeals to self-regulation. Corporate powers are simply expected to refrain from doing so. This contrasts with European attitudes towards violations of privacy which is criminal legislation.

It's only in response to the "War on Terror" and at the behest of the United Kingdom that the European Union expanded police espionage powers. Needless to say, this doesn't apply to corporate intrusions on privacy ... in Europe. In fact, the European Union is set to cease transacting personal information with the USA if it continues to refuse to enact legislation.

Only with this context in mind is it possible to understand certain American citizens' fanatical commitment to absolute privacy. Their governments' hostile actions has led them to quite justified paranoia. It is why the Electronic Frontier Foundation is headquartered in San Francisco and not in Brussels.


text:
User talk:Wizbang

Please stop adding nonsense to Wikibooks. It is considered vandalism. If you would like to experiment, use the sandbox. Thank you.

title: User talk:Wizbang


text: User talk:165.234.100.47

title: User talk:165.234.100.47


text: User talk:209.50.153.101

title: User talk:209.50.153.101


text:
Talk:The Computer Revolution/The Internet Revolution

=To Add=

off of the top of my head:
 * more history of usenet
 * spam and anti-spam
 * The Internet Cabal (the backbone Usenet sites that were able to pay international charges), its rise in ?? and demise in 1984?
 * Yanov and December lists
 * Archie
 * history of InterNic's contract or whatever was that monopolistic DNS company with the goverment contract; it expired in ?
 * registration of fuck.com, trademark and speculation issues with domain names, court cases
 * xxx.archiv.org? the preprint archive and the movement for free scientific publishing
 * First Monday - first internet scholarly journal about the internet
 * foremost authorities on internet Odzlynki, Clay Shirky
 * opencourseware
 * mailing lists, majordomo LISTSERV
 * web-based email
 * web-based groups (Yahoo, Google groups)
 * early CDs of the entire USENET
 * cypherpunks' list and cypherpunks
 * the Electronic Frontier Foundation, John Gilmore was it?
 * PGP -- the guy's defense fund and then his selling out
 * RSA - public key cryptography
 * 64-bit DES? and triple DSS? crackable by the NSA of course
 * the cypherpunks' list kicking out its founder and host
 * repeated efforts for micropayments, electronic money
 * IPv6
 * the creation of POST; postel?
 * evolution of protocols like GGP and NNTP
 * competing protocols to IP: IPX?? ISO's x.25, x.400, and BITNET's whatever
 * history of broadband, ADSL; different technologies worldwide
 * MINITEL in France
 * China's successful censorship efforts, collusion by Yahoo and Cisco
 * ATM and QoS crap; video on demand
 * the ISO OSI's reference model pathetic/grudging concession to packet-switching
 * big companies persistent misunderstanding of the importance of content vs pipe (Graham Bell's conception of the phone network as a way to deliver music)
 * the phone network's switching to packet-switching
 * backbone interchange law
 * CompuServe; it bought supercomputers to handle traffic
 * AOL, its censorship policies and horrible reputation of hosting clueless losers
 * swings in internet activity; especially around September
 * campus internet access
 * attempts to suppress P2P on campuses
 * RIAA killing Napster
 * internet law:
 * ISPs getting regulated under Common Carrier law
 * the DMCA
 * anti-spam California law
 * voice over IP regulation issues in Europe getting shaken down
 * Voice over IP
 * electric utilities becoming broadband ISPs
 * the one city in the US that provided city wide wireless(?) (Philadelphia or Minneapolis?) internet before the shyster US government outlawed it in favour of the sacred market
 * failed FTTH (Fiber to the Home) efforts
 * major rags going on the net, yawn
 * indymedia.org and internet-based political activity
 * porn as a driver of the internet
 * the moderation of ASS
 * the Louvre
 * ASSTR
 * FTP by email (does anyone else remember that? oh man this brings up memories)
 * sunsite? I don't know how significant it was but I remember it a lot. Probably no more significant than Imperial college; just a site that provided lots of interesting anonymous services.
 * Freenets!
 * prices >> 20$ a month for unlimited dialup
 * wikis
 * blogs, livejournal
 * fanfic
 * star trek fanfic archive mismanagement
 * gossamer archive supplanting it
 * usenet newsgroups like atxc and asc
 * fanfiction.net
 * George Lucas' anti-democratic crackdown on Star Wars fans
 * the joint Apple / IBM / Bell study that showed the internet reduced the number and quality of relationships for its users -- its existence censored in North America of course
 * @Home distributed computing
 * the Internet's initial purpose of sharing universities' computing power
 * the Internet 2 for modern university supercomputers
 * fiber optic technology, dark fiber
 * the Last Mile problem
 * the dot com bubble; crash and burn, burn burn burn

 * precursors to IRC
 * how DNS came about (I'm interested because I think it will die eventually)
 * MUDs
 * Lucasfilm's Habitat, and The Lessons Of
 * MMORGs

sources:
 * http://www.livinginternet.com/u/ui_usenethist.htm
 * http://www.livinginternet.com/u/ui_bitnet.htm
 * http://www.livinginternet.com/

= Deletion of Internet Acquisitions List =

The Internet Acquisitions list is deleted from the module for the simple reason that it is:

 * completely useless (is this of interest to anyone? does it educate anyone? I know the answer is a resounding NO to the second question)
 * extremely misleading (it gives the utterly retarded impression that the dot-com bubble explosion was the internet, or at least the web's, revolution; exactly how stupid does one have to be to countenance such a belief?)
 * it is 'grossly incomplete. Hell, Google's acquisition of Deja's Usenet archive didn't even show up there.

The nail in the coffin of my decision to delete the list instead of archiving it as junk is my conviction that it can never be complete. 24.200.176.92 05:10, 10 November 2005 (UTC)

The commercialization of the Internet
One thing that most people may even have a hard time believing now is that commercial activity on the internet not only didn't happen, it was prohibited. The first "crack" in the commercial aspects of the internet was the beginning of a non-profit "classified ad" type notice that was sent out on Usenet. It is hard to imagine now, but there was a time that Usenet didn't have spam and was generally a useful discussion forum for many topics. E-mail spam also at one time didn't exist either, as commercial activity would have not only cut off the internet access for the institution contributing the spam, but the user himself would have faced the equivalent of the internet death penalty. The majority of internet users were also, on the whole, much more skillful with operating systems and it is likely that the person sending spam would have found their hard drive wiped or been subject to a malicious hacker attack. Now it seems as though nobody cares.

The other aspect with the commercialization of the internet was the introduction of America On-Line to the internet. Once upon a time AOL was not connected to the internet and was not an ISP. Oh, they had "talk rooms" and information pages, as well as an internal e-mail system between different AOL subscribers. When AOL became connected to the rest of the internet, there was in some circle a general dread that the internet would never be the same again. And it was changed forever. Typically the cycle was that each fall semiester there would be a new group of new internet users (typically college freshmen trying out the internet for the first time) that would seemingly mangle everything on the internet. After some patience, the earlier group of internet users would try to teach some 'netiquette to these new users and generally these new users would become veterans with the whole process repeating itself each year. When AOL became a part of the internet, all hope was lost. A huge torrent of new users would simply overwhelm the internet and no 'netiquette could ever be taught again.

While not strictly true in practice, the tight-knit community of internet users trying on new ideas just because it was something cool to experiment on ceased to happen in general. Before the commercialization of the internet, all internet practicies were "legislated" from within the community by general concensus. After that commercialization, the legislation happened in national/state legislatures and became issues discussed in the general news media like television and newspapers. Issues like the role of domain naming became something that was commented on by the President of the USA and the UN Secretary-General. In the 1980's that would have been inconcievable to have occured, or even that the President would have even been aware that the internet existed at all.

Another big milestone development in the internet was the establishment of the e-mail address of president@whitehouse.gov

This was established by Al Gore when he became Vice-President, and one of the things I will actually give him credit for. Gore may not have invented the internet, but he did help invent the internet connection to the White House and the Executive branch of the U.S. government. Prior to the Clinton administration, nobody in the White House used the internet at all. After Clinton came into the White House, it became the #1 medium for exchanging memos and daily policy discussions. So much that Congress passed a law (see above) that required the White House to retain all e-mails as official correspondance, which is why President Bush can't send a private e-mail to his daughters.

I hope these details help out. --Rob Horning 01:58, 14 November 2005 (UTC)

I don't have trouble believing it since I lived through it. But I was astonished to find out there was a period of time early on when ARPANET was xenophobic with dictators in charge of it all. The "internet was created by the Pentagon to survive nuclear attack" myth also needs to be countered, especially since the internet couldn't survive a targeted attack. 24.200.176.92 02:15, 26 November 2005 (UTC)


text:
Water Resources Directory/Organizations

Organizations listed by type

 * International government
 * National government
 * State government
 * Local government
 * Government committee (ad hoc)
 * University
 * Professional association
 * Trade association
 * Citizen organization
 * Consulting firm
 * Business-industrial
 * Business-service

Organizations listed by purpose

 * Water Aid
 * Business Partners for Development (BDP) Water and Sanitation Cluster
 * Chartered Institution for Water and Environmental Management
 * Global Water Partnership
 * International Water Association
 * Water and Sanitation Programme
 * Water - World Resources Institute
 * WCA infoNET
 * Health Organization
 * World Water Council

title: Water Resources Directory/Organizations


text: Template:Formal Logic/BookNav

title: Template:Formal Logic/BookNav