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Category:Recipes by type

Recipes organized by the type of dish.

Generally, dish 'types' will be a generic name for a finished recipe or more general class of recipes. If the description of what you are looking for contains the name of any ingredient that goes 'into' the recipe, you may be able to find it at Recipes by ingredient instead. If the description of what you are looking for directly names the national, regional, or ethnic origin of the dish you may be able to find it at Recipes by origin.

fr:Catégorie:Recettes par type de plat it:Categoria:Ricette per portata-tipo tr:Kategori:Türüne göre yemek tarifleri

title: Category:Recipes by type


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

title: User:Rozzychan/Template:Easy1


title: Template:Easy1


title: Template:Intermediate1


title: Template:Advanced1


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User talk:Dr Dnar

Reverse Engineering
I saw your edits on the Reverse Engineering book, and I wanted to personally thank you for the effort. That book always needs to be cleaned up, because most of the contributions to that book are in the form of poorly-worded advertisements to particular hex editors or debuggers. You certainly may list yourself as a contributor there, and I hope you are able to contribute frequently. Let me know if you need anything. --Whiteknight (talk) (projects) 11:55, 25 July 2006 (UTC)
 * Thanks, I'll do so. --Dr Dnar 15:33, 26 July 2006 (UTC)

title: User talk:Dr Dnar


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False Friends of the Slavist/Map russkij

rossijьskъjь


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Biology, Answering the Big Questions of Life/Cells

 Previous < Up > Next : Index

Cells

All Living things are made up of smaller structures called cells.

What is a cell?

 * It is a sack of water that holds in the chemicals that make up life.

A cell is the smallest unit of life. If you look at living organisms under a microscope then you will see they are made up of little square or ball-shaped subunits. Robert Hooke, a British biologist and early microscopist, gave cells their name. While looking at cork slivers under a microscope, he saw that cork was made up of squares that looked like the little rooms (cells) that monks slept in. He called these structures cells.

Later biologists noticed cells everywhere. Two German scientists (Schleiden and Schwann,) formalized this by stating what they called the cell theory. The cell theory simply says that All organisms are composed of one or more cells..

In fact, the modern cell theory has four points.

 * All organisms are composed of one or more cells.
 * All cells come from preexisting cells.
 * All vital functions of an organism occur within cells.
 * Cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.

What types of cells are there?
Cells are divided into two types, Eukaryotes which have a large object called a nucleus in them and Prokaryotes which do not.

Most prokaryotes are very small. Prokaryotes include the two kingdoms: Bacteria and Archea. All of the rest of the kingdoms are Eukaryotes. This includes, Animals, Plants, Fungi, and Protists.

What do cells look like?
Cells are surrounded by a thin oil layer called the plasma membrane (sometimes called the cell membrane).This separates the inside of the cell from the outside. Some cells also have a firm box around them called a cell wall that keeps its structure and prevents it from bursting. The water that fills a cell is called the cytoplasm. Inside a cell information is stored on something called a chromosome. It encodes the information needed to make and run a cell, like an instruction book. This chromosome can be seen as an area that stains dark, called chromatin.

Eukaryotic cells hold their chromosomes in a structure called a nucleus which has its own oily membrane surrounding it. They also have many other membrane bound structures inside them called organelles or little organs. Some organelles found in eukaryotic cells include ribosomes, vacuoles, mitochondria, and chloroplasts.

Cells have different shapes depending on what function they have in the organism, and what kind of life cycle the organism has. A plant leaf cell takes light and uses it to make sugar. To do this, it moves organelles called chloroplasts around so that they can get as much light as possible. To help the cytoplasm flow in circles, the center of the cell is filled with a bubble of water called a vacuole. This large central vacuole is one way to identify plant cells.

A human sperm cell carries its chromosomes, found in the nucleus, to an egg cell in order to make a new baby. The function of the sperm cell helps determine its appearance. It has a large whip-like tail called a flagella that it uses to swim. An acrosome with digestive enzymes to penetrate the egg. It also has many energy producing organelles called mitochondria that help power the flagella like gasoline powers a motor.

Cells come in a great variety of shapes and sizes, but overall they have the same types of structures inside them.

Reading

 * Kingdom_(biology)
 * Cell_(biology)

 Previous Topic < Up /Go deeper> Next Topic : Index


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Talk:Biology, Answering the Big Questions of Life

Greetings
Hello Everyone.

This is my first book. I appreciate any comments that you may have on improving it. Rozzychan

Also please tell me if it is any use at all, or is it a waste of time. Rozzychan 09:58, 25 July 2006 (UTC)

New categories
I decided to take out chapters that I haven't started. I will add the links here.

6. What are plants? - Development stage: 25% (as of Jun 9, 2006)

 * 6. What are plants? -
 * 9. How do we name living things? -

test
1. 2.  3.  4.

বায়োলজি - জীবন সংক্রান্ত জিজ্ঞাসার উত্তর । তনুশ্রী মুখার্জি (discuss • contribs) 05:45, 18 May 2018 (UTC)

authors: তনুশ্রী মুখার্জি


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Talk:Knowing Knoppix/Using an external USB drive

USB Flash disc works fine in Knoppix 4.0.2 Live CD only. But if Knoppix 4.0.2 is installed in the harddisc, then the when inserting the flash disc it does not bring the flash disc icon in the desktop. When trying to look the status of flash disc with 'dmesg' command it says sda1 and the details about the flash disc device. Any help on this is appreciated. Thanks. —The preceding unsigned comment was added by 213.55.64.99 (talk • contribs).

 * I doubt there are any knoppix technicians here. Try http://www.knoppix.net/forum/viewforum.php?f=1 --Snarius 17:06, 25 July 2006 (UTC)


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A-level Applied Science/Choosing and Using Materials/Properties

Stiffness
Stiffness is the resistance of an elastic body to deflection by an applied force.* It is a crude measure because it does not account for the cross-section area, or the length, of the sample. A cuboid rubber will have different stiffness depending on which face you try to compress. The formula for stiffness is the force divided by the change in length.

Stress
Stress is a measure of the force per unit area within a body*. (This is the definition of "Engineering stress" which does not take into account the change in cross-sectional area as the material deforms. "True stress" is force per unit area taking into account the change in area.) This is a better measure than the force alone, because it corrects for the area across which the force applies. Shear stress is stress along the main axis of the material (e.g. pulling on a rope) and normal stress is across the main axis (e.g. flexing a rope). Tensile stress is shear stress which is pulling on an object. Compressive stress is shear stress which is pushing on an object.

Ultimate tensile strength
The tensile strength of a material is the maximum amount of tensile stress that it can be subjected to before failure.* The definition of failure can vary according to material type and design methodology. Ultimate Tensile Strength is the maximum stress a material can withstand without complete fracture.*

Strain
Strain is the deformation caused by the action of stress on a physical body. Strain is measured by calculating the change in length (termed the stretch or absolute strain) and comparing the stretch to the original length.* Strain is positive if the material has gained length (in tension), and negative if it has reduced length (in compression). Strain has no units of measure but sometimes is given as a percentage.* By calculating strain as a percentage we correct for the length of the object.

Young modulus
A better measure than stiffness is the Young modulus. This is the relationship between stress and strain: Because stress accounts for the cross-section area of the sample, and strain for its length, the Young modulus depends only on the material being studied, not its shape.

Young modulus calculations
Complete the following table by using the formula above:

Elasticity and Plasticity
Elasticity is a property of an object: it undergoes elastic (as opposed to plastic) deformation in response to stress.*

Plasticity is a property of a material to undergo a non-reversible change of shape in response to stress. Plastic deformation occurs under shear stress, as opposed to brittle fractures which occur under normal stress. Examples of plastic materials are clay and mild steel. In engineering, this is called yield.* For many ductile metals, tensile loading applied to a sample will cause it to behave in an elastic manner. Each increment of load is accompanied by a proportional increment in extension, and when the load is removed, the piece returns exactly to its original size. This is Hooke's law.* However, once the load exceeds some threshold (the yield strength), the extension increases more rapidly than in the elastic region, and when the load is removed, some amount of the extension remains. A generic graph displaying this behaviour is below.* Ductile materials can sustain large plastic deformations without fracture. However, even ductile metals will fracture when the strain becomes large enough.*

Brittleness
A material is brittle if it is subject to fracture when subjected to stress i.e. it has little tendency to deform (or strain) before fracture.* When used in materials science, it is generally applied to materials that fail due to normal stress rather than shear stress, or when there is little or no evidence of plastic deformation before failure.* When a material has reached the limit of its strength, it usually has the option of either deformation or fracture. A naturally malleable metal can be made stronger by impeding the mechanisms of plastic deformation (reducing grain size, dispersion strengthening, work hardening, etc.), but if this is taken to an extreme, fracture becomes the more likely outcome, and the material can become brittle. Improving material toughness is therefore a balancing act.* This principle applies to other classes of material. Naturally brittle materials, such as ceramics (most famously glass), are difficult to toughen effectively. Most such techniques involve one of two mechanisms: to deflect the tip of a propagating crack, for instance by introducing natural weaknesses of limited extent, or to create carefully controlled residual stresses so that cracks from certain predictable sources will be forced closed, as in the case of toughened glass and pre-stressed concrete.*

Ductility
Ductility is the physical property of being capable of sustaining large plastic deformations without fracture (in metals, such as being drawn into a wire). It is characterized by the material flowing under shear stress.* A ductile material is any material that yields under shear stress (as opposed to brittle fracture, which yields under normal stress). Gold, copper, and aluminium are highly ductile metals.*

Electrical conductivity
Electrical conductivity is a measure of a material's ability to conduct an electric current. When an electrical potential difference is placed across a conductor, its movable charges flow, giving rise to an electric current.* Conductivity is the reciprocal (inverse) of electrical resistivity, and has the SI units of siemens per metre (S m-1). It is commonly represented by the Greek letter σ, but κ or γ are also occasionally used.*

Thermal conductivity
Thermal conductivity, λ or k, is the property of a material which relates its ability to conduct heat. It is the quantity of heat, Q, transmitted due to a temperature difference ΔT. The sample conducting the heat has a thickness L and a cross-section area A.*

 * thermal conductivity = heat flow rate × distance / (area × temperature difference)
 * λ = Q × L / (A × ΔT)

Thermal expansivity
Thermal expansion is the tendency of matter to increase in volume when heated. For liquids and solids the amount of expansion will normally vary depending on the material's coefficient of thermal expansion.*

Density
Density (symbol: ρ - Greek: rho) is a measure of mass per unit of volume. The higher an object's density, the higher its mass per volume. The average density of an object equals its total mass divided by its total volume. A denser object (such as iron) will have less volume than an equal mass of some less dense substance (such as water).* The SI unit of density is the kilogram per cubic metre (kg m−3)* although grams per cubic centimetre (g cm−3) is also used because the numbers are more convenient.

Resistance to chemicals
Chemical resistance is the ability of a substance to withstand exposure to acids, alkalis, solvents and other chemicals.

Some materials are chosen because they can be used in an environment which contains dangerous chemicals; or to protect vulnerable components, or people, against dangerous chemicals. An example is Teflon, which was developed to make valves which could handle the highly corrosive compound UF6 in the Manhattan project.

Permeation is a process by which a chemical can pass through a protective film without going through pinholes, pores, or other visible openings. Individual molecules of the chemical enter the film, and “squirm” through by passing between the molecules of the protective compound or film. In many cases the permeated material may appear unchanged to the human eye.

Chemical permeation can be described in simple terms by comparing it to what happens to the air in a balloon after several hours. Although there are no holes or defects, and the balloon is tightly sealed, the air gradually passes through (permeates) its walls and escapes. This simple example uses gas permeation, but the principle is the same with liquids or chemicals.

Degradation is a reduction in one or more physical properties of a material due to contact with a chemical. Certain materials may become hard, stiff, or brittle, or they may grow softer, weaker, and swell to several times their original size. If a chemical has a significant impact on the physical properties of a material, its permeation resistance is quickly impaired.

Assignment

 * 1) Identify different examples of materials with each mechanical property listed above;
 * 2) State why the value of each mechanical property is relevant to the use to which the material is to be put, and compare given values for each mechanical property;

Methods for measuring physical properties
Manufacturers of materials need to be aware of methods for measuring physical properties. These could be used to test new materials or as a quality control check in a factory.

You will need to be aware of simple laboratory experiments to measure the values of physical properties. You will need to be able to measure the following physical properties for a range of materials including metals, ceramics, glass, polymers and composites:

 * a mechanical property;
 * density;
 * electrical conductivity;
 * thermal conductivity;
 * resistance to chemicals;
 * thermal expansion/contraction.

You will need to be aware of experiments that test the physical properties of materials. The specific experiments you should be aware of are: You will need to be able to use this formula to calculate a value for the Young modulus of a material. You will then need to compare this value to given values and relate this to particular uses of a material.
 * the determination of Hooke’s law and how to relate the relevant physical properties of the material (elasticity, elastic limit, permanent deformation, plasticity, break point) to the molecular structure of the material;
 * Searle’s experiment to calculate the stiffness of a material and how this can then be related to the Young modulus of a material using the formula

You should show an awareness that in a commercial environment these experiments will often be done quite differently than in a school laboratory, sometimes on a much larger scale and often more rigorously.

Searle’s method for finding the Young’s modulus of a wire
Searle’s method uses two wires of the same material, one of which will be loaded with various weights.

E = $$\frac{F l}{A x}$$

To calculate Young’s modulus we need to know:

 * The cross-section area of the wire (A). This is measured by using a micrometer to determine the radius of the wire, and then using the formula area of circle = πr2. The radius must be measured in metres, and is typically 2 x 10−4 m. This gives an area of 1.26 x 10−7 m2.
 * The length of the wire (l, measured in metres).
 * The force and the extension.
 * The weight of a 1 kg mass is 9.81 N.

We plot a graph of the extension (m, horizontal axis) against the weight (N, vertical axis).

The gradient of this graph (change in vertical measure / change in horizontal measure) is the ratio F/x. If we multiply this ratio by l and divide by A we have the Young modulus for the wire. Measuring the extension:

The ‘business end’ of the apparatus is a device which holds the two wires parallel, and allows the extension of the loaded wire to be measured.

You need to label this diagram to show:
 * Constant mass attached to stress the reference wire.
 * Variable mass attached to stress the test wire.
 * Flexible connectors.
 * Level reference from one wire to the other.
 * Thumbscrew with scale to level the reference.
 * Clamps for wires.
 * Reference wire.
 * Test wire.

Advantages of this apparatus:
 * The thermal expansion of the test wire is accounted for by the thermal expansion of the reference wire.
 * Long, thin wires allow maximum extension for minimum force.

Problems:
 * Difficulty measuring the cross-section area.
 * Extensions very small.
 * Mass, not weight, is measured.
 * Need high, secure mounting point unless apparatus adapted.

Equations
There are three equations given in the specification that you need to know. See the relevant section for a fuller description in each case.

Thermal conductivity

 * thermal conductivity = heat flow rate × distance / (area × temperature difference)
 * λ = Q × L / (A × ΔT)

Density

 * density = mass / volume
 * ρ = m / V

where p=rho> Greek letter given to density

Young modulus

 * The Young modulus of elasticity = stress / strain
 * E = $$\frac{F l}{A x}$$

 * stress = force/ area = F / A
 * strain = extension / length = x / l


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A-level Applied Science/Choosing and Using Materials/Structure and properties

Relating the physical properties of materials to their structure
Materials behave as they do because of their structure; the way their atoms and molecules fit together. Materials scientists consider how materials behave at the atomic level in order to assess the suitability of a material for a specific project.

You should understand how physical properties relate to:
 * the microscopic structure of crystalline, polymeric and amorphous materials;
 * the structure of composite materials;
 * strong bonding between particles (ionic, covalent and metallic);
 * weak bonding between particles.

Strong bonding between particles

 * Ionic – directional : Although all cations attract all anions, each cation is surrounded by anions and vice-versa. Moving one part of the ionic lattice will cause anion-anion and cation-cation repulsions.

 * Covalent – directional: : Covalent bonds are between specific atoms and distorting the positions of the atoms will break the bonds.

 * Metallic - non-directional.
 * The fluid ‘sea’ of electrons can accommodate changes in the crystal structure, so the shape of the sample can change without breaking the bonds.
 * Compounds which are purely ionic or covalent have low ductility. Metals are much more ductile.

Weak bonding between particles.
 * The strong bonding of metals, ionic crystals and giant covalent molecules extends throughout the material.

Intermolecular bonding
Small covalent molecules, polymers, graphite etc. are not composed of a single molecule. What holds one molecule to another molecule? The answer is intermolecular bonding.

There are three types of intermolecular bond:

 * Van der Waals’ forces
 * Every molecule and atom will be very weakly attracted to any other molecule or atom. This is because the electrons on one particle will be attracted to the nuclei of the other, and vice-versa.
 * This type of bonding is very weak. Small molecules which bond in this way will be gases. Very large molecules can accumulate enough van der Waals’ force to form solids (e.g. polymers, graphite) but they are mechanically weak unless stressed along/across their covalent bonds.

 * Dipole-dipole interactions
 * Polar molecules (molecules containing atoms such as oxygen, nitrogen, fluorine, chlorine) have permanent areas of positive and negative charge. These molecules can stick together like pairs of magnets.
 * This bonding is stronger than van der Waals’ bonding and quite like ionic bonding. Molecules that bond in this way tend to be less volatile than pure van der Waals’ substances. Polymers with dipole-dipole bonding tend to be stiffer than hydrocarbon polymers e.g PVC.

 * Hydrogen bonding
 * If hydrogen is bound to an oxygen or nitrogen, it can bind to the oxygen or nitrogen of a second molecule. This is the strongest intermolecular bond and is akin to covalent bonding.
 * Molecules that hydrogen bond are the least volatile molecules. Simple molecules will be they are brittle. E.g. sugar but polymers tend to be stiff and brittle, e.g cellulose, perspex.


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A-level Applied Science/Choosing and Using Materials/Microscopic structure

Microscopic structure
We need to consider crystalline, polymeric and amorphous materials;

 * Crystalline materials : may be ionic, metallic or giant covalent.
 * The atoms are packed in a regular pattern. This gives great strength, but in the case of ionic and covalent crystals, and molecules held by dipole-dipole or hydrogen bonds, the crystal structure fractures if placed under strain.

 * Polymeric materials : are either long covalent molecules, held together by intermolecular bonds; or a giant molecule. The latter are the thermoset polymers which behave like crystalline materials.
 * Thermoplastic polymers become ductile when heated and can be moulded into shape. Cold-drawing the polymer (imposing plastic strain while the material is at room temperature) will line-up the polymers chains. Cold-drawn polymer is very strong in the direction it was strained, because its strength comes from the covalent bonds of it molecules, not the intermolecular bonds.

 * Amorphous materials : include glass and polymers. Amorphous polymers are discussed above, but note that if the intermolecular bonds are strong and directional (e.g. Perspex, polystyrene) then the polymers becomes brittle. Glass is also brittle, and for the same reason – straining the material breaks the bonds that hold it together. In the case of glass these are covalent bonds.

The structure of composite materials.
Composite materials combine the properties of two or more simple materials. For example, glass fibre combines a tough flexible resin with strong fibres of glass.

The interaction between the two materials is also important. Cracks may be stopped from opening because they form in one material but cannot pass through the other one.


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A-level Applied Science/Choosing and Using Materials/Classes of materials

The different classes of materials
Materials can be grouped into classes according to their composition. You should know:
 * the basic categories of materials . metals, ceramics, glasses, polymers and a group of combined materials known as composites.

You should be able to:

 * give examples of uses of each of these basic categories of materials and be able to offer and justify a range of common uses of these materials in different situations such as construction, domestic goods, industrial plant, medical applications and sports equipment;
 * investigate how the properties of the categories of materials influence their use.

For each class of material, you will need to give examples of their uses, with justification:

(“X is used for Y because it is A, B and C.” e.g. 'Copper' is used for 'domestic wiring' because it has a 'low electrical conductivity', is 'flexible' and 'cheap'.)

Consider uses such as
 * construction
 * domestic goods
 * industrial plant
 * medical applications
 * sports equipment

The basic categories of materials: 1 metals
Metals are crystalline materials with the uniquely fluid metallic bonding. The free electrons of metallic bonding make metals reflective and electrically- and thermally conductive.

The metallic bonding makes the structure able to sustain strain. Metals are can be hard, but are also ductile and tough. They are strong when subjected to all sorts of stress.

Metals can be shaped when cold (they are plastic/ductile) or melted and formed into new shapes by casting (they are thermoplastic).

The basic categories of materials: 2 ceramics
Ceramics are crystalline materials. As such, they tend to be opaque.

The bonding is ionic or covalent, which makes the structure unable to sustain strain. Ceramics are hard, inflexible and brittle. They are strong when subjected to compressive stress, but not to tensile stress or normal stress.

Ceramics are formed by the chemical reaction of plastic precursors e.g. clay. Once formed, they cannot be re-moulded i.e. they are thermoset.

The basic categories of materials: 3 glasses
Glasses are amorphous materials: They have no crystal structure. Glasses are amorphous ceramics but it is possible to make amorphous metals and amorphous polymers.

Being amorphous, glasses are transparent. Their properties are similar to ceramics except that they are thermoplastic.

The basic categories of materials: 4 polymers
Polymers can be crystalline or amorphous. Amorphous polymers tend to be clear whereas crystalline ones are opaque.

Crystalline polymers are 'anisotropic': Their properties vary depending on whether they are tested along their polymer chains (strong, rigid) or across the chains (weak, ductile).

Amorphous polymers have average properties in all directions of testing (they are 'isotropic').

Thermoplastic polymers consist of long chains, which when heated will become fluid and can then be re-moulded to new shapes.

Some thermoplastic polymers have such strong intermolecular bonding that the heat required to melt them is more than the heat required to make them combust. These behave like thermoset polymers.

Thermoset polymers are like ceramics: They are formed from fluid precursors but form a permanent 3D lattice of covalent bonds which is impossible to melt. Like ceramics, thermoset polymers are brittle. Unlike ceramics, thermoset polymers are softer, less dense and much less heat resistant.

Examples

 * Steel-reinforced concrete : Concrete has excellent resistance to compressive stress, and is cheap and durable. Steel is expensive and corrodes but has excellent resistance to tensile and normal stresses.
 * Carbon fibre reinforced plastic
 * Plastics are tough but flexible. Carbon fibre has tremendous tensile strength but little resistance to compressive or normal stress (it buckles). Both materials are very low density.
 * Combining plastic and carbon fibre gives a tough, strong, lightweight material. By varying the direction of weave of the carbon fibre, the properties can be made anisotropic. If a fibre breaks, the plastic transfers the stress to other fibres.

 * Plywood
 * Wood is anisotropic – it is considerable weaker to stresses which are tensile or normal to the grain of the wood.
 * Plywood has layers of wood at right angles, so that stress in any direction is tensile to the grain of some layers of wood. The glue which binds the plywood also adds to its strength.


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Haskell/Higher-order functions

At the heart of functional programming is the idea that functions are just like any other value. The power of functional style comes from handling functions themselves as regular values, i.e. by passing functions to other functions and returning them from functions. A function that takes another function (or several functions) as an argument is called a higher-order function. They can be found pretty much anywhere in a Haskell program, and indeed we have already met some of them, such as  and the various folds. We saw commonplace examples of higher-order functions when discussing  in Lists II. Now, we are going to explore some common ways of writing code that manipulates functions.

A sorting algorithm
For a concrete example, we will consider the task of sorting a list. Quicksort is a well-known recursive sorting algorithm. To apply its sorting strategy to a list, we first choose one element and then divide the rest of the list into (A) those elements that should go before the chosen element, (B) those elements equal to the chosen one, and (C) those that should go after. Then, we apply the same algorithm to the unsorted (A) and (C) lists. After enough recursive sorting, we concatenate everything back together and have a final sorted list. That strategy can be translated into a Haskell implementation in a very simple way.

It should be pointed out that our  is rather naïve. A more efficient implementation would avoid the three passes through  at each recursive step and not use   to build the sorted list. Furthermore, unlike our implementation, the original quicksort algorithm does the sorting in-place using mutability. We will ignore such concerns for now, as we are more interested in the usage patterns of sorting functions, rather than in exact implementation.

The class
Almost all the basic data types in Haskell are members of the  class, which is for ordering tests what   is for equality tests. The  class defines which ordering is the "natural" one for a given type. It provides a function called, with type:

takes two values and compares them, returning an  value, which is   if the first value is less than the second,   if it is equal and   if it is greater than. For an  type, ,   from   and   can be seen as shortcuts to   that check for one of the three possibilities and return a   to indicate whether the specified ordering is true according to the   specification for that type. Note that each of the tests we use with  in the definition of   corresponds to one of the possible results of , and so we might have written, for instance,   as.

Choosing how to compare
With, sorting any list with elements in the   class is easy. Suppose we have a list of  and we want to sort them; we just apply   to the list. For the rest of this chapter, we will use a pseudo-dictionary of just a few words (but dictionaries with thousands of words would work just as well):

returns:

As you can see, capitalization is considered for sorting by default. Haskell s are lists of Unicode characters. Unicode (and almost all other encodings of characters) specifies that the character code for capital letters are less than the lower case letters. So "Z" is less than "a".

To get a proper dictionary-like sorting, we need a case insensitive. To achieve that, we can take a hint from the discussion of  just above. The recursive case of  can be rewritten as:

While this version is less tidy than the original one, it makes it obvious that the ordering of the elements hinges entirely on the  function. That means we only need to replace   with an  function of our choice. Therefore, our updated  is a higher-order function which takes a comparison function along with the list to sort.

We can reuse our  function to serve many different purposes.

If we wanted a descending order, we could just reverse our original sorted list with. Yet to actually do the initial sort descending, we could supply  with a comparison function that returns the opposite of the usual.

Higher-Order Functions and Types
The concept of currying (the generating of intermediate functions on the way toward a final result) was first introduced in the earlier chapter "Lists II". This is a good place to revisit how currying works.

Our  has type.

Most of the time, the type of a higher-order function provides a guideline about how to use it. A straightforward way of reading the type signature would be " takes, as its first argument, a function that gives an ordering of two  s. Its second argument is a list of  s. Finally, it returns a new list of  s". This is enough to correctly guess that it uses the given ordering function to sort the list.

Note that the parentheses surrounding  are mandatory. They specify that  forms a single argument that happens to be a function.

Without the parentheses, we would get  which accepts four arguments (none of which are themselves functions) instead of the desired two, and that wouldn't work as desired.

Remember that the  operator is right-associative. Thus, our erroneous type signature  means the same thing as.

Given that  is right-associative, the explicitly grouped version of the correct   signature is actually. This makes perfect sense. Our original  lacking the adjustable comparison function argument was of type. It took a list and sorted it. Our new  is simply a function that generates   style functions! If we plug in  for the   part, then we just return our original simple   function. If we use a different comparison function for the argument, we generate a different variety of a  function.

Of course, if we not only give a comparison function as an argument but also feed in an actual list to sort, then the final result is not the new -style function; instead, it continues on and passes the list to the new function and returns the sorted list as our final result.

Function manipulation
We will close the chapter by discussing a few examples of common and useful general-purpose higher-order functions. Familiarity with these will greatly enhance your skill at both writing and reading Haskell code.

Flipping arguments
is a handy little Prelude function. It takes a function of two arguments and returns a version of the same function with the arguments swapped.

in use:

We could have used flip to write a point-free version of the  comparing function from the quickSort example:

is particularly useful when we want to pass a function with two arguments of different types to another function and the arguments are in the wrong order with respect to the signature of the higher-order function.

Composition
The  composition operator is another higher-order function. It has the signature:

takes two functions as arguments and returns a new function which applies the second function to the argument and then the first. (Writing the type of  as   can make that easier to see.)

Composition and higher-order functions provide a range of powerful tricks. For a tiny sample, first consider the function, defined in the module. Quoting the documentation, it "returns all initial segments of the argument, shortest first", so that:

We can provide a one-line implementation for  (written point-free for extra dramatic effect) using only the following higher-order functions from Prelude: ,  ,   and  :

Swallowing a definition so condensed may look daunting at first, so analyze it slowly, bit by bit, recalling what each function does and using the type signatures as a guide.

The definition of  is super concise and clean with use of parentheses kept to a bare minimum. Naturally, if one goes overboard with composition by writing mile-long  chains, things will get confusing; but, when deployed reasonably, these point-free styles shine. Furthermore, the implementation is quite "high level": we do not deal explicitly with details like pattern matching or recursion; the functions we deployed — both the higher-order ones and their functional arguments — take care of such plumbing.

Application
is a curious higher-order operator. Its type is:

It takes a function as its first argument, and all it does is to apply the function to the second argument, so that, for instance,.

You might think that  is completely useless! However, there are two interesting points about it. First,  has very low precedence, unlike regular function application which has the highest precedence. In effect, that means we can avoid confusing nesting of parentheses by breaking precedence with. We write a non-point-free version of  without adding new parentheses:

Furthermore, as  is just a function which happens to apply functions, and functions are just values, we can write intriguing expressions such as:

(Yes, that is a list of functions, and it is perfectly legal.)

and
As the name suggests,  is a function that undoes currying; that is, it converts a function of two arguments into a function that takes a pair as its only argument.

One interesting use of  occasionally seen in the wild is in combination with , so that the first element of a pair is applied to the second.

There is also, which is the opposite of.

Because most Haskell functions are already curried,  is nowhere near as common as.

and
Finally, we should mention two functions which, while not higher-order functions themselves, are most often used as arguments to higher-order functions. , the identity function, is a function with type that returns its argument unchanged.

Similar in spirit to,   is an  function that works like this:

takes two arguments, discards the second and returns the first. Seen as a function of one argument,, it returns a constant function, which always returns the same value no matter what argument it is given.

and  might appear worthless at first. However, when dealing with higher-order functions it is sometimes necessary to pass a dummy function, be it one that does nothing with its argument or one that always returns the same value. and  give us convenient dummy functions for such cases.

title: Haskell/Higher-order functions


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A-level Applied Science/Investigating Science at Work

About this Unit
From the AQA Specification:

 You need to produce a portfolio of evidence to show how science is used to provide products and services in different kinds of science based organisations.

How you will be assessed
This unit is assessed through the work you complete for your portfolio.

The marking criteria are found in the AQA Specification.

What you need to know
The types of organisation which use science.

How science is used in organisations.

How health and safety regulations are used in the workplace.

How the organisation impacts on the local community.

Resources
The specification requires you to identify and use appropriate research methods to complete your portfolio. It will not be possible, therefore, for this textbook to give extensive details on any of the sections your portfolio needs. Below are some suggestions and links you might find useful:

Research methods.

Health and safety regulations.

INCO case study.

GlaxoSmithKline site for applied science - how science is used in the pharmaceutical industry.


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Talk:Biology, Answering the Big Questions of Life/Photosynthesis/Photosynthesis3

Please correct me if I am wrong about the Magnesium atom. I can't find where I read this. Rozzychan 10:38, 25 July 2006 (UTC)

 * I do not find any evidence that says the electron that is excited comes from magnesium +2 ion. The third ionization of magnesium takes 80 eV.  Chlorophyll a and b take about 4 eV to ionize one electron.  The energy to strip an electron off of Mg+2 is twenty times that of a chlorophyll.  It is much more likely the electron comes from the pi electron cloud of the tetrapyrole.   224238scott (discuss • contribs) 23:16, 31 May 2023 (UTC)


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Template:Cheese

| Cheese

Usage
This template also takes an optional sort key for the category:

Effect

 * This template uses the ingredient template to specify that the article is about an ingredient
 * It adds " | Cheese" to the navigation field
 * Unless the parameter noincludecat is specified, the article is added to Category:Cheeses
 * For example,  will not add the article to any categories

title: Template:Cheese


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A-level Applied Science/Investigating Science at Work/Health and safety

Safety regulations
Summary of:
 * HSE Guide to Risk Assessment Requirements.
 * Five Steps to Risk Assessment.

What is a risk assessment?
Risk assessments became a legal obligation under the Control of Substances Hazardous to Health (COSHH) Act of 1988.

Since then, the idea has become part of all health & safety regulations.

 * Who assesses risks?

Employers (including the self-employed). Outside help may be used.
 * Who is at risk?

Yourself, your workers, members of the public.

 * What risks are assessed?

Anything that could cause harm to people.

“Adequate”/”Suitable and sufficient”. Precautions taken against hazards need also be assessed.
 * How thorough should the assessment be?

 * When to assess?

Before starting work
 * Records

Necessary if five or more employees. Need to be kept on file for a period of time.
 * Review

Regular review is good practice. Review must be carried out if the work has changed significantly.

 * 1) STEP 1: Look for the hazards
 * 2) STEP 2: Decide who might be harmed and how
 * 3) STEP 3: Evaluate the risks and decide whether the existing precautions are adequate or whether more should be done
 * 4) STEP 4: Record your findings
 * 5) STEP 5: Review your assessment and revise it if necessary

Main sources of regulation

 * Management of Health and Safety at Work Regulations 1999 (Management Regulations);
 * Manual Handling Operations Regulations 1992 (Manual Handling Regulations);
 * Personal Protective Equipment at Work Regulations 1992 (PPE);
 * Health and Safety (Display Screen Equipment) Regulations 1992 (Display Screen Regulations);
 * Noise at Work Regulations 1989 (Noise Regulations);
 * Control of Substances Hazardous to Health Regulations 1999 (COSHH);
 * Control of Asbestos at Work Regulations 1987 (Asbestos Regulations);
 * Control of Lead at Work Regulations 1998 (Lead Regulations).
 * There are also regulations dealing with highly specialised risks such as major hazards, ionising radiation, genetic manipulation etc.

British Standards and Kitemarks
British Standards is a trading division of the British Standards Institution and is part of BSI Group which also includes a testing organisation. British Standards has a Royal Charter to act as the standards organisation for the UK. It is formally designated as the National Standards Body (NSB) for the UK.

BSI group incorporates three divisions - the Standards division which publishes British Standards, the Product Services division (the "Kitemark") and the Mananagement Systems division, a management systems registrar.

The standards produced are titled British Standard XXXX where XXXX is the number of the standard. British Standards currently has over 17,000 active standards. Products are commonly specified as meeting a particular British Standard, and in general this can be done without any certification or independent testing. The standard simply provides a shorthand way of claiming that certain specifications are met, while encouraging manufacturers to adhere to a common method for such a specification.

The Kite Mark can be used to indicate certification by the BSI, but only where a Kite Mark scheme has been set up around a particular standard. It is mainly applicable to safety and quality management standards. There is a common misunderstanding that Kite Marks are necessary to prove compliance with any BS standard, but in general it is neither desirable nor possible that every standard be 'policed' in this way.

Another key activity carried out by British Standards is the CE Marking of Medical Devices. The CE 0086 marking can be issued to devices that are found to comply with the Medical Device Directive.

Frequently used BS standards

 * BS 1363 for mains power plugs and sockets
 * BS 546 for mains power plugs and sockets (older standard)
 * BS 5750 for quality management, the source for ISO 9000
 * BS 5950 for structural steel
 * BS 6312 for telephone plugs and sockets
 * BS 6879 for British geocodes, a superset of ISO 3166-2:GB
 * BS 7799 for information security, the source for ISO 17799
 * BS 8110 for structural concrete
 * BS 15000 for IT Service Management, (ITIL), now ISO 20000

External links & references

 * Official website
 * BSI Online Shop
 * info4education – allows users at many British universities to download selected British Standards via an ATHENS login


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A-level Applied Science/Investigating Science at Work/Types of science organisation

Applied science is the application of knowledge from one or more scientific fields to practical problems. Many applied sciences can be considered forms of engineering. Applied science is important for technology development.

Academic disciplines that may be considered to be applied sciences include agriculture, architecture, education, engineering, ergonomics, design, family and consumer science, forestry, forensics, health sciences, library and information science, medicine and military science. There are also applied branches of most other sciences.

Instrumental science, an applied science, is a systematic way of solving problems. It is not a science of discovery but rather deals with manipulation to solve a particular problem such as "The crops are dying. We need to find a way to stop this." Instrumental sciences are well known for research and development which result in new technology.

In researching local science-based businesses, include firms which are involved in:

(1) Producing:

• products from plants, animals or microbes;

• water, gas, oil, gravel, clay, stone or minerals;

• chemicals, paints, dyes, fertilisers and plastics;

• pharmaceuticals, for example medicines;

• mechanical or electrical devices;

• refined fuels;

• processed and packaged products.

(2) Providing services:

• health;

• conservation and use of the environment;

• monitoring the environment;

• animal welfare;

• analysis;

• communication;

• education in science and technology;

• distributing and selling food and other products;

• distributing energy resources.


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Talk:Cognitive Psychology and Cognitive Neuroscience/Decision Making and Reasoning

Tja, was soll ich sagen? Man sieht halt wenn sich eine Gruppe mühe gibt ;) --Aschoeke 12:19, 17 August 2006 (UTC)

Jemand von ausserhalb:)

Auch von mir noch eine kleine Anmerkung zur Einleitung: Schaut euch nochmal die Einleitung von z.B. der ersten Gruppe an. Ich finde eure noch etwas zu trocken, wenn ihr versteht was ich meine. Gibt es nicht irgendein Beispiel, welches man zur Einleitung benutzen kann? In welchen Lebenslagen ist es beispielhaft wichtig oder vielleicht witzig sich zu entscheiden? Ich werde auch darueber nachdenken. Ansonsten habt ich noch ein paar Formulierungsfehler, also wo sich das Englisch noch ein wenig zu Deutsch anhoert. Ich werd mal ein wenig rumfurwerken, ihr habt ja keine Nachteile davon.

Lg Imme

Hallo Leute!

Hier schonmal die Ansätze von Ellen und mir (Nina). Wär' gut, wenn Ihr so schnell wie möglich (bis spätestens Freitag) Eure Sachen auch hochladen könntet. Dann kann man ja noch per Telefon und/oder E-Mail besprechen, wie wir das ganze noch ein bisschen homogener gestalten (und auch mit der Einleitung abgleichen). Wenn jemand Fragen oder Anregungen zu den Texten bis jetzt hat, immer her damit!

Liebe Grüße Ellen & Nina

So, ich betrachte meinen inductive reasoning Text als fertig. Das einzige, was ich vonwegen cross-references gerne hätte, wäre ein Link ganz am Anfang von 'deductive reasoning' zu unserem ersten Thema nach oben und von 'inductive reasoning' zu dem normalen Wiki-Artikel dadrüber. Weiß wer, wie das geht?

Und wie sieht's aus mit der Reference List? Ich hab' nur den Goldstein und Schmali's Slides benutzt, und ein bisschen über den Artikel bei Wikipedia drüber gelesen. Links zum Thema hätte ich auch keine... muss ich nochmal gucken.

Ich habe mir überdies erlaubt, ein bisschen an der Einleitung rumzuwerkeln. Just minor changes taking into account the reviews and stuff. Lest sie bitte mal durch und sagt, wie sie Euch gefällt.

LG Nina

Halli hallo,

ich hab mir mal alles gut durchgelesen und so manche Kleinigkeiten ganz dreist verbessert, also fast nur Rechtschreibfehler... Einleitung find ich auf jeden Fall besser so! Mit der Reference Liste wollte ich mich morgen nochmal beschäftigen; Soll ich die fettgedruckten Sachen aus dem decision making text wieder rausnehmen, oder wollt ihr auch noch was markieren? Und ein paar mehr Absätze und Bildchen wären bei deductive reosing vielleicht noch ganz cool. Was machen wir denn jetzt mit der "Notfalllücke" thinking categorically??? Das wär ja Christins Sache gewesen, ist auch glaub ich nicht zu wenig... so können wir den Anfang von thinking conditionally ja auch schlecht stehen lassen. Ausserdem bräuchten wir ja noch eine dicke Überschrift "Executive Function" und die ersten beiden Kapitel davon fehlen auch noch?! (Deficits in initiation, ... und Impairments in abstract...) Na ja, erstmal einen schönen Gruss, Ellen

So, Mädels,

ich hab jetzt mal die References nach APAStyle:-) aufgeschrieben, noch ein bisschen was "verbessert" und ein paar Sachen verlinkt: Frage - sollen wir ALLES verlinken? Also immer wenn das Wort wiedererstscheint, den Link dazu angeben? die meisten Wikitexte sind ja ziemlich gut mit blauen Sachen durchzogen, wär vielleicht gar nicht so verkehrt, was? Geht eigentlich ganz schnell, vielleicht setz ich mich da morgen nochmal hinter... Na ja, insgesamt zieht es aber doch viel "unauffällige Zeit" muss ich sagen und eigentlich bin ich gerade auch nicht top motiviert, den ganzen fehlenden Text noch selber zu schreiben... Watt meinta? Bis demnächst:-)

01.08. Also, ich hab' jetzt nochmal kurz an den Links was geändert, ich finde es irgendwie besser, wenn nicht die Überschriften direkt gelinkt sind sondern immer das erste Mal, dass das Thema dann im Text genannt wird, das ist bei Wikipedia glaub' ich auch so üblich.

Und ich hab' versucht, meine Cross-References zu machen, weiß jemand, wie man Links im eigenen Buch in ein anderes Kapitel setzt? Ich hab' die jetzt als externe Links, aber das ist wohl Blödsinn... naja, funktioniert auch.

Ich würde gern noch das ein oder andere Bildchen reinpacken, wie geht denn das? Muss ich das hochladen und wie?

Meint Ihr, wir sollen nochmal eine Liste mit ein paar Links zum Thema machen? Aber das sind ja eigentlich so viele verschiedene Themen... Oder vielleicht nur welche zu den beiden Bibeln?

Achso, hab' Schmalis Slides bei References geadded. Haben die anderen auch alle.

Also, an die, die bis jetzt noch nicht soviel Einsatz gezeigt (hat|haben): versuch(t) bitte (Deiner|Eurer) Gruppennote gerecht zu werden! Ist nur 'ne Bitte (noch) nicht bös' gemeint...

LG Nina

02.08. Mit den links im Text ists echt schicker... wegen cross-references; ich weiss es auch nicht, aber es gibt doch extra ne Gruppe, die nichts anderes als das machen - und da ist glücker/zufälliger weise Thorben drin. Der hat mein Bildchen auch reingepackt und gesagt, es hätt nicht lang gedauert und ihm Spass gemacht. Man muss die ja noch irgendwie abmalen und bla wegen den Rechten... Was machen wir denn nu mit Christins Teilen? nochmal aufteilen und hoffen, dass es nicht zu zerstückelt wird??? Na ja, ich bleib am Ball, aber auch nicht mehr all zu lange:-)

03.08. Bildchen abmalen? Dann mach ich wohl doch keine Bildchen rein... Ich dachte, Christins Teile hätten wir schon längst aufgeteilt? Ich meine, das war doch rechtzeitig genug, danach ist doch erst alles richtig verteilt worden? Ich weiß es nicht, ich war ja nicht dabei, aber ds höre ich echt zum ersten Mal, dass wir vielleicht noch mehr Themen übernhemen müssen. Werd' ich auch nicht tun, ich hab' ab nächster Woche Ferien und Basta. Außer minor changes wird da von mir nichts mehr kommen, kann sich ja mal das Gruppenmitglied, das bisher in diesen Ferien nur mit Abwesenheit und Unerreichbarkeit, wie ich höre, geglänzt hat, drum kümmern. So seh' ich das!

Naja, however, hab'ne Linkliste gebastelt, war wohl 'n bisschen lahm, hab' einfach gegoogelt und die Links genommen, deren content ich gut fand, aber wird wohl ok sein, oder? Besser als nix... Ach ja, der ethical bla Link bei decision making führt nicht zu 'ner religiösen Sekte, oder so, oder? Ich fand', das sah gut aus, aber man weiß ja nie, nicht dass es da noch Probleme gibt.

Haut rein LG Nina

04.08. Sehr cool, Nina, die Links sind toll! na ja, so ein Drogenthema ist doch ne wichtige ethische Entscheidungsfrage...:-) tja, ich hab jetzt ehrlich gesagt auch keinen Bock, mich hier in meinem Urlaub noch für das ganze Thema zu erbarmen... Janine?! Sonst tipp ich noch schnell irgendwas am 18.8 darein, aber erstmal noch abwarten, fürs erste find ich unser Buch ganz ok... Ein feedback kriegen wir wsl doch nicht, höchstens ganz grobe Fehler... na ja - vielleicht dann bis Mittwoch? Ich meld mich aber:-)

hallo ihr drei, sorry dass ich mich erst jetzt melde, wie ihr wisst bin ich in england und im totalen umzugsstress, also kann ich nicht oft schreiben. ich hab jetzt alles mal ueberflogen und finde es eigentlich auch recht gut gelungen, danke euch auch dass ihr euch so ins zeug legt. ich werd in den naechsten tagen nochmal den "lack..." teil ueberarbeiten, und soweit ich weiss wird janine den thinking categorically teil machen. aber was ich nicht in ordnung finde ist dass ihr (du nina) eure kritik an die gruppe in die diskusion rein schreibt wo sie jeder lesen kann. ich denke das ist eine sache die wir auch per email haetten klaeren koennen... wie dem auch sei, wenn irgendwas sein sollte, dann meldet euch bitte bei mir... ich werd versuchen meinen teil noch so schnell wie moeglich fertig zu bekommen. uebrigens find ich das wirklich gut mit den links usw. ich wuensch euch noch schoene erholsame ferien. bis die tage u liebe gruesse, lilli

Hi, hi,

so, ich hab jetzt die beiden approaches von deductive reasoning noch relativ kurz zusammengefasst, fehlt nur noch das Bild. Ich werd nächste Woche auch nochmal reinschauen, lesen und Kleinigkeiten verbessern, aber eigentlich müsste`s das für meinen Teil ja so ziemlich gewesen sein. Ach Lilli, Nina hat sich übrigens bereit erklärt, den BanichTeil zu übernehmen:-) So Mädels, dann trotzdem noch einen schönen Urlaub, bis die Tage (gibt bestimmt doch noch wieder unverhofft mehr zu regeln:-) )

18.08. Hallo nochmal, ich hab auf Immes Tipp nochmal den Anfang der Einleitung geändert, aber weitere Verbesserung erwünscht:-) hoffe mal, bis morgen ist alles vollständig?! Wir hören voneinander, viele Grüsse!

20.08. Hallo auch von mir! Melde, dass mit den letzten beiden Bildchen (thanks go to Thorben K. aus O.) von meiner Seite alles komplett ist. Würde mir, wenn es nicht schon zu spät ist, vielleicht auch nochmal die Einleitung ansehen, aber ansonsten, kann man denke ich damit leben. Hoffe doch, dass Andrejs Kommentar oben positiv gemeint ist. Naja, whatever, in diesem Sinne ist dieses Projekt wohl so gut wie abgeschlossen (Cross- und andere Wiki-References?). Hat im Großen und Ganzen aber trotzdem Spaß gemacht, fand' ich, und war sehr informativ. Danke an alle, die mitgemacht haben!

LG und noch schöne Ferien Nina


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Human Physiology/Integumentary System

Introduction
The integumentary system consists of the skin, hair, nails, the subcutaneous tissue below            the skin,and assorted  glands.The most obvious function of the integumentary system is the protection that the skin gives to underlying tissues. The skin not only keeps most harmful substances out, but also prevents the loss of fluids. A major function of the subcutaneous tissue is to connect the skin to underlying tissues such as muscles. Hair on the scalp provides insulation from cold for the head. The hair of eyelashes and eyebrows helps keep dust and perspiration out of the eyes, and the hair in our nostrils helps keep dust out of the nasal cavities. Any other hair on our bodies no longer serves a function, but is an evolutionary remnant. Nails protect the tips of fingers and toes from mechanical injury. Fingernails give the fingers greater ability to pick up small objects. There are four types of glands in the integumentary system: Sudoriferous glands, Sebaceous glands, Ceruminous glands, and Mammary glands. Sudoriferous glands are sweat producing glands. These are important to help maintain body temperature. Sebaceous glands are oil producing glands which help inhibit bacteria, keep us waterproof and prevent our hair and skin from drying out. Ceruminous glands produce earwax which keeps the outer surface of the eardrum pliable and prevents drying. Mammary glands produce milk.

Skin
In zoology and dermatology, skin is an organ of the integumentary system made up of a layer of tissues that guard underlying muscles and organs. As the interface with the surroundings, it plays the most important role in protecting against pathogens. Its other main functions are insulation and temperature regulation, sensation and vitamin D and B synthesis. Skin is considered one of the most important parts of the body.

Skin has pigmentation, melanin, provided by melanocytes, which absorbs some of the potentially dangerous radiation in sunlight. It also contains DNA repair enzymes which reverse UV damage, and people who lack the genes for these enzymes suffer high rates of skin cancer. One form predominantly produced by UV light, malignant melanoma, is particularly invasive, causing it to spread quickly, and can often be deadly. Human skin pigmentation varies among populations in a striking manner. This has sometimes led to the classification of people(s) on the basis of skin color.

Damaged skin will try to heal by forming scar tissue, often giving rise to discoloration and depigmentation of the skin.

The skin is often known as "the largest organ in the human body". This applies to exterior surface, as it covers the body, appearing to have the largest surface area of all the organs. Moreover, it applies to weight, as it weighs more than any single internal organ, accounting for about 15 percent of body weight. For the average adult human, the skin has a surface area of between 1.5-2.0 square meters, most of it is between 2-3 mm thick. The average square inch of skin holds 650 sweat glands, 20 blood vessels, 60,000 melanocytes, and more than a thousand nerve endings.

The use of natural or synthetic cosmetics to treat the appearance of the face and condition of the skin (such as pore control and black head cleansing) is common among many cultures.

Layers
The skin has two major layers which are made of different tissues and have very different functions. Skin is composed of the epidermis and the dermis. Below these layers lies the hypodermis or subcutaneous adipose layer, which is not usually classified as a layer of skin.

The outermost epidermis consists of stratified squamous keratinizing epithelium with an underlying basement membrane. It contains no blood vessels, and is nourished by diffusion from the dermis. The main type of cells which make up the epidermis are keratinocytes, with melanocytes and Langerhans cells also present. The epidermis can be further subdivided into the following strata (beginning with the outermost layer): corneum, lucidum, granulosum, spinosum, basale. Cells are formed through mitosis at the innermost layers. They move up the strata changing shape and composition as they differentiate, inducing expression of new types of keratin genes. They eventually reach the corneum and become sloughed off (desquamation). This process is called keratinization and takes place within about 30 days. This layer of skin is responsible for keeping water in the body and keeping other harmful chemicals and pathogens out.

Blood capillaries are found beneath the dermis, and are linked to an arteriole and a venule. Arterial shunt vessels may bypass the network in ears, the nose and fingertips.

The dermis lies below the epidermis and contains a number of structures including blood vessels, nerves, hair follicles, smooth muscle, glands and lymphatic tissue. It consists of loose connective tissue otherwise called areolar connective tissue—collagen, elastin and reticular fibers are present. Erector muscles, attached between the hair papilla and epidermis, can contract, resulting in the hair fiber pulled upright and consequentially goose bumps. The main cell types are fibroblasts, adipocytes (fat storage) and macrophages. Sebaceous glands are exocrine glands which produce a mixture of lipids and waxy substances known as sebum. Sebum serves many functions, including lubrication, water-proofing, softening, and also provides antimicrobial properties. Sweat glands open up via a duct onto the skin by a pore.

The dermis is made of an irregular type of fibrous connective tissue consisting of collagen and elastin fibers. It can be split into the papillary and reticular layers. The papillary layer is outermost and extends into the epidermis to supply it with vessels. It is composed of loosely arranged fibers. Papillary ridges make up the lines of the hands giving us fingerprints. The reticular layer is more dense and is continuous with the hypodermis. It contains the bulk of the structures (such as sweat glands). The reticular layer is composed of irregularly arranged fibers and resists stretching.

The hypodermis is not part of the skin, and lies below the dermis. Its purpose is to attach the skin to underlying bone and muscle as well as supplying it with blood vessels and nerves. It consists of loose connective tissue and elastin. The main cell types are fibroblasts, macrophages and adipocytes (the hypodermis contains 95% of body fat). Fat serves as padding and insulation for the body.

Functions

 * 1) Protection: Skin gives an anatomical barrier between the internal and external environment in bodily defense; Langerhans cells in the skin are part of the immune system
 * 2) Sensation: Skin contains a variety of nerve endings that react to heat, cold, touch, pressure, vibration, and tissue injury; see somatosensory system and touch.
 * 3) Heat regulation: The skin contains a blood supply far greater than its requirements which allows precise control of energy loss by radiation, convection and conduction. Dilated blood vessels increase perfusion and heat loss while constricted vessels greatly reduce cutaneous blood flow and conserve heat. Erector pili muscles are significant in animals.

Tumors

 * Benign tumors of the skin: Squamous cell papilloma
 * Skin cancer
 * Acne
 * Keratosis pilaris
 * Fungal infections such as athlete's foot
 * microbial infections
 * calcinosis cutis
 * ulcer

Types of hair
Humans have three different types of hair:
 * Lanugo, the fine, unpigmented hair that covers nearly the entire body of a fetus, although most has been replaced with vellus by the time of the baby's birth
 * Vellus hair, the short, downy, "peach fuzz" body hair (also unpigmented) that grows in most places on the human body. While it occurs in both sexes, and makes up much of the hair in children, men have a much smaller percentage (around 10%) vellus whereas 2/3 of a female's hair is vellus.
 * Terminal hair, the fully developed hair, which is generally longer, coarser, thicker, and darker than vellus hair, and often is found in regions such as the axillary, male beard, and pubic.

Pathological impacts on hair
Drugs used in cancer chemotherapy frequently cause a temporary loss of hair, noticeable on the head and eyebrows, because they kill all rapidly dividing cells, not just the cancerous ones. Other diseases and traumas can cause temporary or permanent loss of hair, either generally or in patches.

The hair shafts may also store certain poisons for years, even decades, after death. In the case of Col. Lafayette Baker, who died July 3, 1868, use of an atomic absorption spectrophotometer showed the man was killed by white arsenic. The prime suspect was Wallace Pollock, Baker's brother-in-law. According to Dr. Ray A. Neff, Pollack had laced Baker's beer with it over a period of months, and a century or so later minute traces of arsenic showed up in the dead man's hair. Mrs. Baker's diary seems to confirm that it was indeed arsenic, as she writes of how she found some vials of it inside her brother's suit coat one day.

Parts of the fingernail

The fingernail is an important structure made of keratin. The fingernail generally serve two purposes. It serves as a protective plate and enhances sensation of the fingertip. The protection function of the fingernail is commonly known, but the sensation function is equally important. The fingertip has many nerve endings in it allowing us to receive volumes of information about objects we touch. The nail acts as a counterforce to the fingertip providing even more sensory input when an object is touched.

Nail Structure
The structure we know of as the nail is divided into six specific parts - the root, nail bed, nail plate, eponychium (cuticle), perionychium, and hyponychium.

Root The root of the fingernail is also known as the germinal matrix. This portion of the nail is actually beneath the skin behind the fingernail and extends several millimeters into the finger. The fingernail root produces most of the volume of the nail and the nail bed. This portion of the nail does not have any melanocytes, or melanin producing cells. The edge of the germinal matrix is seen as a white, crescent shaped structure called the lunula.

Nail Bed The nail bed is part of the nail matrix called the sterile matrix. It extends from the edge of the germinal matrix, or lunula, to the hyponychium. The nail bed contains the blood vessels, nerves, and melanocytes, or melanin-producing cells. As the nail is produced by the root, it streams down along the nail bed, which adds material to the undersurface of the nail making it thicker. It is important for normal nail growth that the nail bed be smooth. If it is not, the nail may split or develop grooves that can be cosmetically unappealing.

Nail Plate The nail plate is the actual fingernail, made of translucent keratin. The pink appearance of the nail comes from the blood vessels underneath the nail. The underneath surface of the nail plate has grooves along the length of the nail that help anchor it to the nail bed.

eponychium The cuticle of the fingernail is also called the eponychium. The cuticle is situated between the skin of the finger and the nail plate fusing these structures together and providing a waterproof barrier.

Perionychium The perionychium is the skin that overlies the nail plate on its sides. It is also known as the paronychial edge. The perionychium is the site of hangnails, ingrown nails, and an infection of the skin called paronychia.

Hyponychium The hyponychium is the area between the nail plate and the fingertip. It is the junction between the free edge of the nail and the skin of the fingertip, also providing a waterproof barrier.

Nail Diseases
Nail diseases are in a separate category from diseases of the skin. Although nails are a skin appendage, they have their own signs and symptoms which may relate to other medical conditions. Nail conditions that show signs of infection or inflammation require medical assistance and cannot be treated at a beauty parlor. Deformity or disease of the nails may be referred to as onychosis.

There are many disease that can occur with the fingernails and toenails. The most common of these diseases are ingrown nails and fungal infections.

Ingrown Nails
Onychocryptosis, commonly known as "ingrown nails" (unguis incarnatus), can affect either the fingers or the toes. In this condition, the nail cuts into one or both sides of the nail bed, resulting in inflammation and possibly infection. The relative rarity of this condition in the fingers suggests that pressure from the ground or shoe against the toe is a prime factor. The movements involved in walking or other physical disturbances can contribute to the problem. Mild onychocryptosis, particularly in the absence of infection, can be treated by trimming and rounding the nail. More advanced cases, which usually include infection, are treated by surgically excising the ingrowing portion of the nail down to its bony origin and cauterizing the matrix, or 'root', to prevent recurrence. This surgery is called matricectomy. The best results are achieved by cauterizing the matrix with phenol. Another method, which is much less effective, is excision of the matrix, sometimes called a 'cold steel procedure'

Nail Fungus
An infection of nail fungus (onychomycosis) occurs when fungi infect one or more of your nails. Onychomycosis generally begins as a white or yellow spot under the tip of the fingernail or toenail. As the nail fungus spreads deeper into the nail, it may cause the nail to discolor, thicken and develop crumbling edges — an unsightly and potentially painful problem.

Infections of nail fungus account for about half of all nail disorders. These infections usually develop on nails continually exposed to warm, moist environments, such as sweaty shoes or shower floors. Nail fungus isn't the same as athlete's foot, which primarily affects the skin of the feet, but at times the two may coexist and can be caused by the same type of fungus. Topical steroid misuse is one of the most common cause now a days.

An infection with nail fungus may be difficult to treat, and infections may recur. But medications are available to help clear up nail fungus permanently.

Clinical Application
Nail inspection can give a great deal of information about the internal working of the body as well, and like tongue or iris inspection, has a long history of diagnostic use in cantraditional medical practices such as Chinese medicine.

Pliability:

Brittleness is associated with iron deficiency, thyroid problems, impaired kidney function, circulation problems[2], and biotin deficiency[3] Splitting and fraying are associated with psoriasis, folic acid, protein and/or Vitamin C deficiency. Unusual thickness is associated with circulation problems. Thinning nails and itchy skin are associated with lichen planus[4].

Shape and texture:

Clubbing, or nails that curve down around the fingertips with nail beds that bulge is associated with oxygen deprivation and lung, heart, or liver disease. Spooning, or nails that grow upwards is associated with iron or B12 deficiency. Flatness can indicate a B12 vitamin deficiency[5] or Raynaud's disease[6] Pitting of the nails is associated with Psoriasis. Horizontal ridges indicate stress, and Beau's lines are associated with many serious conditions. Vertical ridges are associated with arthritis[7]. Vertical grooves are associated with kidney disorders, aging, and iron deficiency[8]. Beading is associated with rheumatoid arthritis[9]. Nails that resemble hammered brass are associated with (or portend) hair loss[10]. Short small beds are associated with heart disease[11].

Coloration of the nail bed:

Mee's lines are associated with arsenic or thallium poisoning, and renal failure. White lines across the nail are associated with heart disease, liver disease, or a history of a recent high fever[12]. Opaque white nails with a dark band at the fingertip are associated with cancer, cirrhosis, congestive heart failure, diabetes and aging[13]. Paleness or whitening is associated with liver or kidney disease and anemia[14]. Yellowing of the nail bed is associated with chronic bronchitis, lymphatic problems, diabetes, and liver disorders. Brown or copper nail beds are associated with arsenic or copper poisoning, and local fungal infection. Grey nail beds are associated with arthritis, edema, malnutrition, post-operative effects, glaucoma and cardio-pulmonary disease[15]. redness is associated with heart conditions. dark nails are associated with B12 deficiency. Stains of the nail plate (not the nail bed) are associated with nail polish[16], smoking, and henna use.

Markings:

Pink and white nails are associated with kidney disease[17]. Parallel white lines in the nails are associated with hypoalbuminemia. red skin at the base of the nail is associated with connective tissue disorders[18]. blue lunulae are associated with silver poisoning or lung disorder[19]. blue nail beds are (much like blue skin) associated with poor oxygenation of the blood (asthma, emphysema, etc)[20]. small white patches are associated with zinc or calcium deficiency or malabsorption, parasites, or local injury[21]. receded lunulae (fewer than 8) are associated with poor circulation[22], shallow breathing habits or thyroid dysfunction[23]. large lunulae (more than 25% of the thumb nail) is associated with high blood pressure.

Sudoriferous(Sweat Glands)
In humans, there are two kinds of sweat glands which differ greatly in both the composition of the sweat and its purpose: Also "click" here|"How our body Sweats" to see a short movie on sweat glands.

Eccrine (a.k.a. merocrine)
Eccrine sweat glands are exocrine glands distributed over the entire body surface but are particularly abundant on the palms of hands, soles of feet, and on the forehead. These produce sweat that is composed chiefly of water (99%) with various salts. The primary function is body temperature regulation.

Eccrine sweat glands are coiled tubular glands derived leading directly to the most superficial layer of the epidermis (outer layer of skin) but extending into the inner layer of the skin (dermis layer). They are distributed over almost the entire surface of the body in humans and many other species but are lacking in some marine and fur-bearing species. The sweat glands are controlled by sympathetic cholinergic nerves which are controlled by a center in the hypothalamus. The hypothalamus senses core temperature directly, and also has input from temperature receptors in the skin and modifies the sweat output, along with other thermoregulatory processes.

Human eccrine sweat is composed chiefly of water with various salts and organic compounds in solution. It contains minute amounts of fatty materials, urea, and other wastes. The concentration of sodium varies from 35–65 mmol/l and is lower in people acclimatized to a hot environment. The sweat of other species generally differs in composition.

Apocrine
Apocrine sweat glands only develop during early- to mid-puberty (approximately age 15) and release more than normal amounts of sweat for approximately a month and subsequently regulate and release normal amounts of sweat after a certain period of time. Apocrine sweat glands produce sweat that contains fatty materials. These glands are mainly present in the armpits and around the genital area and their activity is the main cause of sweat odor, due to the bacteria that break down the organic compounds in the sweat from these glands. Emotional stress increases the production of sweat from the apocrine glands, or more precisely: the sweat already present in the tubule is squeezed out. Apocrine sweat glands essentially serve as scent glands.

In some areas of the body, these sweat glands are modified to produce wholly different secretions, including the cerumen ("wax") of the outer ear. Other glands, such as Mammary glands, are greatly enlarged and modified to produce milk.

Sebaceous Glands
The sebaceous glands are glands found in the skin of mammals. They secrete an oily substance called sebum (Latin, meaning fat or tallow) that is made of fat (lipids) and the debris of dead fat-producing cells. These glands exist in humans throughout the skin except in the palms of the hands and soles of the feet. Sebum acts to protect and waterproof hair and skin, and keep them from becoming dry, brittle, and cracked. It can also inhibit the growth of microorganisms on skin.

Sebaceous glands can usually be found in hair-covered areas where they are connected to hair follicles to deposit sebum on the hairs, and bring it to the skin surface along the hair shaft. The structure consisting of hair, hair follicle and sebaceous gland is also known as pilosebaceous unit. Sebaceous glands are also found in non haired areas of lips, eyelids, penis, labia minora and nipples; here the sebum reaches the surface through ducts. In the glands, sebum is produced within specialized cells and is released as these cells burst; sebaceous glands are thus classified as holocrine glands.

Sebum is odorless, but its bacterial breakdown can produce odors. Sebum is the cause of some people experiencing "oily" hair if it is not washed for several days. Earwax is partly sebum, as is mucopurulent discharge, the dry substance accumulating in the corners of the eye after sleeping.

The composition of sebum varies from species to species; in humans, the lipid content consists of about 25% wax monoesters, 41% triglycerides, 16% free fatty acids, and 12% squalene.

The activity of the sebaceous glands increases during puberty because of heightened levels of androgens.

Sebaceous glands are involved in skin problems such as acne and keratosis pilaris. A blocked sebaceous gland can result in a sebaceous cyst. The prescription drug isotretinoin significantly reduces the amount of sebum produced by the sebaceous glands, and is used to treat acne. The extreme use (up to 10 times doctor prescribed amounts) of anabolic steroids by bodybuilders to prevent weight loss tend to stimulate the sebaceous glands which can cause acne.

The sebaceous glands of a human fetus in utero secrete a substance called Vernix caseosa, a "waxy" or "cheesy" white substance coating the skin of newborns.

The preputial glands of mice and rats are large modified sebaceous glands that produce pheromones.

Ceruminous glands

Earwax, also known by the medical term cerumen, is a yellowish, waxy substance secreted in the ear canal of humans and many other mammals. It plays a vital role in the human ear canal, assisting in cleaning and lubrication, and also provides some protection from bacteria, fungus, and insects. A comprehensive review of the physiology and pathophysiology of cerumen can be found in Roeser and Ballachanda. Excess or impacted cerumen can press against the eardrum and/or occlude the external auditory canal and impair hearing.

Production, composition, and different types
Cerumen is produced in the outer third of the cartilaginous portion of the human ear canal. It is a mixture of viscous secretions from sebaceous glands and less-viscous ones from modified apocrine sweat glands.

Two distinct genetically determined types of earwax are distinguished -- the wet-type which is dominant, and the dry type which is recessive. Asians and Native Americans are more likely to have the dry type of cerumen (grey and flaky), whereas Caucasians and Africans are more likely to have the wet type (honey-brown to dark-brown and moist). Cerumen type has been used by anthropologists to track human migratory patterns, such as those of the Inuit.

The difference in cerumen type has been tracked to a single base change (an single nucleotide polymorphism) in a gene known as "ATP-binding cassette C11 gene". In addition to affecting cerumen type, this mutation also reduces sweat production. The researchers conjecture that the reduction in sweat was beneficial to the ancestors of East Asians and Native Americans who are thought to have lived in cold climates.

Function
Cleaning. Cleaning of the ear canal occurs as a result of the "conveyor belt" process of epithelial migration, aided by jaw movement. Cells formed in the center of the tympanic membrane migrate outwards from the umbo (at a rate equivalent to that of fingernail growth) to the walls of the ear canal, and accelerate towards the entrance of the ear canal. The cerumen in the canal is also carried outwards, taking with it any dirt, dust, and particulate matter that may have gathered in the canal. Jaw movement assists this process by dislodging debris attached to the walls of the ear canal, increasing the likelihood of its extrusion.

Lubrication. Lubrication prevents desiccation and itching of the skin within the ear canal (known as asteatosis). The lubricative properties arise from the high lipid content of the sebum produced by the sebaceous glands. In wet-type cerumen at least, these lipids include cholesterol, squalene, and many long-chain fatty acids and alcohols.

Antibacterial and antifungal roles. While studies conducted up until the 1960s found little evidence supporting an antibacterial role for cerumen, more recent studies have found that cerumen provides some bactericidal protection against some strains of bacteria. Cerumen has been found to be effective in reducing the viability of a wide range of bacteria (sometimes by up to 99%), including Haemophilus influenzae, Staphylococcus aureus, and many variants of Escherichia coli. The growth of two fungi commonly present in otomycosis was also significantly inhibited by human cerumen. These antimicrobial properties are due principally to the presence of saturated fatty acids, lysozyme and, especially, to the relatively low pH of cerumen (typically around 6.1 in normal individuals).

Mammary Glands
Mammary glands are the organs that, in the female mammal, produce milk for the sustenance of the young. These exocrine glands are enlarged and modified sweat glands and are the characteristic of mammals which gave the class its name.

Structure
The basic components of the mammary gland are the alveoli (hollow cavities, a few millimetres large) lined with milk-secreting epithelial cells and surrounded by myoepithelial cells. These alveoli join up to form groups known as lobules, and each lobule has a lactiferous duct that drains into openings in the nipple. The myoepithelial cells can contract, similar to muscle cells, and thereby push the milk from the alveoli through the lactiferous ducts towards the nipple, where it collects in widenings (sinuses) of the ducts. A suckling baby essentially squeezes the milk out of these sinuses.

One distinguishes between a simple mammary gland, which consists of all the milk-secreting tissue leading to a single lactiferous duct, and a complex mammary gland, which consists of all the simple mammary glands serving one nipple.

Humans normally have two complex mammary glands, one in each breast, and each complex mammary gland consists of 10-20 simple glands. (The presence of more than two nipples is known as polythelia and the presence of more than two complex mammary glands as polymastia.)

Also, "click" this;|"Breast tissue", to this a movie visual of the breast.

Development and hormonal control
The development of mammary glands is controlled by hormones. The mammary glands exist in both sexes, but they are rudimentary until puberty when in response to ovarian hormones, they begin to develop in the female. Click this to see what breast tissue does in a female during menstruation. Estrogen promotes formation, while testosterone inhibits it.

At the time of birth, the baby has lactiferous ducts but no alveoli. Little branching occurs before puberty when ovarian estrogens stimulate branching differentiation of the ducts into spherical masses of cells that will become alveoli. True secretory alveoli only develop in pregnancy, where rising levels of estrogen and progesterone cause further branching and differentiation of the duct cells, together with an increase in adipose tissue and a richer blood flow.

Colostrum is secreted in late pregnancy and for the first few days after giving birth. True milk secretion (lactation) begins a few days later due to a reduction in circulating progesterone and the presence of the hormone prolactin. The suckling of the baby causes the release of the hormone oxytocin which stimulates contraction of the myoepithelial cells.

Breast cancer
As described above, the cells of mammary glands can easily be induced to grow and multiply by hormones. If this growth runs out of control, cancer results. Almost all instances of breast cancer originate in the lobules or ducts of the mammary glands.

Types of breast cancer
 * DCIS: Ductal Carcinoma in Situ
 * LCIS: Lobular Carcinoma in Situ
 * Invasive ductal carcinoma
 * Invasive lobular carcinoma
 * Inflammatory breast cancer
 * Paget's disease

Homeostasis
As a whole, the integumentary system plays a big part in maintaining homeostasis. The integumentary system is the outermost organ system of the body and many of its functions are related to this location. The skin protects the body against pathogens and chemicals, minimizes loss or entry of water, and blocks the harmful effects of sunlight. Sensory receptors in the skin provide information about the external environment, helping the skin regulate body temperature in response to environmental changes and helping the body react to pain and other tactile stimuli. The large surface area of the skin makes it ideal for temperature regulation. The rate of heat loss can be regulated by the amount of blood flowing through the blood vessels in the dermis close to the surface of the skin. When the body temperature rises, as for example during exercise, sympathetic tone is reduced and this brings about dilation of the blood vessels supplying the skin. The increase in skin blood flow allows heat to be lost more rapidly so that body temperature does not rise above the normal homeostatic range. The rate of heat loss can also be boosted by the production of sweat, which takes up additional heat as it evaporates. Conversely, if heat production is less than required, the dermal vessels constrict, sweating stops, and heat is conserved by the body.

Glossary

 * Areolar:Areolar connective tissue is a pliable, mesh-like tissue with a fluid matrix and functions to cushion and protect body organs. It acts as a packaging tissue holding the internal organs together and in correct placement.

 * Basal lamina :Basal lamina (often erroneously called basement membrane) is a layer on which epithelium sits. This layer is composed of an electron-dense layer (lamina densa) between two electron-lucid layers (lamina lucida), and is approximately 40-50 nm thick (with exceptions such as the 100-200 nm glomerular basement membrane).

 * Dermis : The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain.  The dermis is tightly connected to the epidermis by a basement membrane.

 * Epidermis : The epidermis is the outermost layer of the skin. It forms the waterproof, protective wrap over the body's surface and is made up of stratified squamous epithelium with an underlying basal lamina.

 * Fibroblasts :A fibroblast is a cell that makes the structural fibers and ground substance of connective tissue.

 * Hair follicle :A hair follicle is part of the skin that grows hair by packing old cells together.

 * Hypodermis : The hypodermis (also called the hypoderm), is the lowermost layer of the integumentary system in vertebrates. It is derived from the mesoderm, but unlike the dermis, it is not derived from the dermatome region of the mesoderm.

 * Impetigo: This is a superficial skin infection most common among children age 2–6 years. People who play close contact sports such as rugby, American football and wrestling are also susceptible, regardless of age. The name derives from the Latin impetere ("assail"). It is also known as school sores.

 * Melanocytes :These are cells located in the bottom layer of the skin's epidermis and in the middle layer of the eye, the uvea. Through a process called melanogenesis, these cells produce melanin, a pigment in the skin, eyes, and hair.

 * Melanoma : A melanoma is a malignant tumor that originates in melanocytes.   It is a highly malignant form of skin cancer, and, though rare, is responsible for the majority of skin cancer-related deaths.

 * Onychosis :Deformity or disease of the nails

 * Papillary : The papillary layer is outermost and extends into the epidermis to supply it with vessels. It is composed of loosely arranged fibres. Papillary ridges make up the lines of the hands.

 * Recticular Layer : The reticular layer is more dense and is continuous with the hypodermis. It contains the bulk of the structures (such as sweat glands). The reticular layer is composed of irregularly arranged fibres and resists stretching.

 * For more fun pictures of other skin diseases and skin problems "click" to this cool website: |"Dermatology Image Database". Note: From this link then click "Clinical Skin Diseases Images".

Review Questions

 * Answers for these questions can be found here

1. Name all of the parts of the integumentary system.

2. Name the cells that produce melanin and describe its function.

3. Name and describe the importance of the cutaneous senses.

4. Explain how sweating helps maintain normal body temperature.

5. Explain where on the body hair has important functions and describe these functions.

6. What is a melanoma?

A) The outermost layer of skin

B) A type of nail disease

C) A malignant tumor that originates in melanocytes

D) The lower most layer of skin

title: Human Physiology/Integumentary System


text:
Cookbook:Southeast Asian Cuisines

| Asian Cuisine

 * Cuisine of Brunei
 * Cuisine of Cambodia
 * Cuisine of East Timor
 * Cuisine of Indonesia
 * Cuisine of Laos
 * Cuisine of Malaysia
 * Cuisine of Myanmar
 * Cuisine of the Philippines
 * Cuisine of Singapore
 * Cuisine of Thailand
 * Cuisine of Vietnam

title: Cookbook:Southeast Asian Cuisines