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User talk:Ikarsik

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HSC Extension 1 and 2 Mathematics/Linear functions
There are errors on that page with the math syntax. If you need help to fix the TeX markup, ask at WB:TECH. Happy editing! – Mike.lifeguard  | talk 03:10, 2 December 2007 (UTC)

Nice Edits
I saw your edits to MIPS and Circuit Theory. Thanks for the help! Every little bit helps, and even small edits make books better. --Whiteknight (Page) (Talk) 01:32, 16 January 2008 (UTC)

Congratulations also for all the corrections you are making on the C++ Programming book, big help thanks... --Panic (talk) 04:48, 17 January 2008 (UTC)

Hello again
Where was the problem you detected on the print version? I have restored it to the previous state so we can fix it (duplicating the all chapters will not fix it and will break the auto-update functionality that was created, editors will have to remember to edit both pages, and that is prone to generate errors). Due to transclusions taking some time to update (probably the error you mentioned was due to that) it will take some time for the serve to restore the structure (probably more than 24h), try to check in the all chapters version (that should be the same without some of the print version text). I will also take a closer look also later to see if I detect any problem. (You can use the by chapter view to make it easier, all views are structured as to represent smaller parts of the bigger page that is the print version) --Panic (talk) 15:39, 16 April 2008 (UTC)

The TOC problem should be a minor one, as stated in the header that information should not get printed, if it is then I or someone else have probably forced a toc on a low content subpage to help navigation (I remember doing something like that somewhere) but was confident that the print version would not print it... --Panic (talk) 15:43, 16 April 2008 (UTC)

 * The problem I saw with the print version was with putting
 * in the print version code. It made a link to All_Chapters instead of including its text. It might just do that for me though, or you might want that. The only thing that the print version page has that All_Chapters doesn't is the license, so if you added the license to the All_Chapters page, you could use that as your print version, because a print version should have all chapters. Shouldn't it?
 * in the print version code. It made a link to All_Chapters instead of including its text. It might just do that for me though, or you might want that. The only thing that the print version page has that All_Chapters doesn't is the license, so if you added the license to the All_Chapters page, you could use that as your print version, because a print version should have all chapters. Shouldn't it?

 * I know in the code for the Fundamentals section there is a above the transcludes, but by removing that the TOC is moved down further in the page to another section that has TOC forced. I didn't want to go through just getting rid of TOCs because that might make the single page views look very bad. When I put the transcludes from All_Chapters in the print version after  a TOC still shows up because  in the Fundamentals chapter overrides  at the top of the print versions code. This doesn't really matter for registered users because we can turn off TOCs in preferences, but unregistered readers would get the TOC just before the Fundamentals chapter when reading it. Not a big issue but I couldn't really do anything else to help so I just decided to try and fix this. Please check this, sorry for any inconvenience, and hello again to you too =) rawrawrer (talk) 18:16, 16 April 2008 (UTC)

 * Hummm I see, what you saw was the same that is present now ? only a link, this can be due to two things something was changes in the way transclusion works or some change was made and the server hasn't yet updated the output. Lets see if it takes more than 24h to update and if it does we should ask in the administration area why it stopped working.
 * The previous, and what we want is the view of the all chapters with the inclusion of the license (needed to satisfy its requirements on the print version) also the top header removes some of the navigation schemes from the output (like TOCs) so it should solve the last part of your post above, even if it is shown when you view the print version, it will not be present (as the warning box), it will be removed.
 * Well let's wait and see if the trasnclusion is updated, if not then something was changed or some error exists on the page, I can swear that it worked as intended but not on this location the creation date of the page to recent (04:47, 5 November 2006) so I can't check if something was different or altered. I think what is happening is that since the page is generated form another transcluded page if any change is done down the chain it will have to be generated for the hole collection to work, since I recently moved some pages that maybe the reason also. --Panic (talk) 19:17, 16 April 2008 (UTC)

 * I've asked User talk:Mike.lifeguard to see if he reaches the same conclusion or knows of a feasible alternative. --Panic (talk) 19:25, 16 April 2008 (UTC)

 * Ok, so it works now and User:Mike.lifeguard has removed all the forced TOCs from the pages, so no more TOC in the middle of the book. Thanks Mike! But this still has the code from All_Chapters being copied to the print versions code, so updating All_Chapters wont update the print version. Maybe if we transcluded the individual pages in All_Chapters instead of the chapters containing them, which transclude the pages anyway, the software would let us transclude All_Chapters. rawrawrer (talk) 08:15, 17 April 2008 (UTC)

Hic
That last wording/logic correction made my skin crawl a lot more that normal because the previous edition was attributed to me. I take this chance to state that I only have the blame of not having noticed that before :) hic... Great work on proofreading  it (I have asked several persons to take to that task but I've come to believe that most people doesn't read books cover to cover any more, at least technical books). I can have some blame on some crazy wording as my first language isn't English and I do some of the edits at weird hours, any way it's 11.01 a.m and I'm off to bed now, I just checked your last work and couldn't sleep without commenting on it :)  --Panic (talk) 10:05, 18 April 2008 (UTC)

 * thankyou =). I'm just reading quickly through the intro part. I'll probably do better proofreading in the object oriented chapter, because I never bothered to learn any of that the first time I looked at c++, so it will all be new material. I'm not really worried about the spelling, as long as I can read it. I made a quick PDF file for fun for this book, I'll upload it later and put the tag on the TOC1 page. It's messy but I think some of the pages look pretty good, and adobe reader can generate the bookmarks for each section. rawrawrer (talk) 11:50, 18 April 2008 (UTC)

 * I will move for the to removal TOC2, it always created problems, in navigation and the logical flow of the content. Most people don't use it and it has not been maintained. If that occurs it will restore TOC1 to the front page and restore navigation (no fallback to the multiple toc page to resume reading). I don't know if that will also help the PDF navigation (I never created a PDF from a Wikibook). I prefer reading on the screen than on real paper. Did multiple TOC created any problem on the PDF?  --Panic (talk) 18:55, 18 April 2008 (UTC)
 * The code highlight in off on the PDF. O solution to remove TODOs from the print version should also be studied and the green syntax label that I've been using on the C Standard Library has lost it's box rendering it very ugly, may it be a result of a skin change you made on Wikibooks ? --Panic (talk) 19:25, 18 April 2008 (UTC)

 * I noticed that, but just ignored it. I think it is caused by the way I created the PDF. I had never created a PDF from a wikibook either and so I just tested it by saving the print page as a html file then opening it in OpenOffice.org writer and doing some basic formatting then exporting it to PDF. I'm pretty sure the change in formatting is caused by the monobook.css and common.css styling rules being left out. I think this might just be firefox not saving the css files locally, or something, so maybe if I just add the styling rules in at the start of the saved html file it will all be good. Meh, I'll look at it later. I just wanted C++ Programming to look like it meant business with a PDF file and all.

 * But the removal of the protected page with links to all 3 TOCs will be great. There hasn't been any talk on that for a while now, so there shouldn't be any opposition (right?). rawrawrer (talk) 19:58, 18 April 2008 (UTC)

 * I can only hope. It has all been my fault, I did think having multiple structures of a single book could be great and the framework (Wikibooks) does permit it, the only problem was the navigational aspect (only one of the navigations could be dominant), before User:Darklama implemented TOC2 there was another TOC also (deprecated by lack of use) that fallowed the main TOC but implemented a distinct navigational and layout scheme. Problems arose because TOC2 did not fallow the structural integrity of the previous TOCs it shifted pages and chapters (TOC1 did try to comply with some of the new views to enable the changes and in the long run it did improve structurally). My main objection was that User:Darklama changes were made unilaterally and disregarding stated oposition (that lead to moving TOC2 to the front page), deletionist (removed content due to idea that the book should be smaller and more to the point as in stick only to the standard side not the practical aspects, most alterations have still to be verified)...). User:Darklama has now created a new C++ book that would enable him to express his vision. To be fair and transparent I will have inform him that I'll be pushing for the pages removal, lets see if he can live with the changes...
 * As result that mess I'm also pushing for the prohibition of additional TOCs, see the conventions discussion page. --Panic (talk) 20:17, 18 April 2008 (UTC)

Japanese Wikibook discussion
Hi Ikarsik,

I just added a comment on Talk:Japanese which I wanted to draw your attention to as you've been involved in this book. --Swift (talk) 14:49, 10 June 2008 (UTC)

title: User talk:Ikarsik


text:
User talk:Miketm~enwikibooks

Hello and welcome to Wikibooks!

Here are some tips to help you get started:
 * You can sign your name on Talk and vote pages using four tildes, like this: ~~~~.
 * Remember to conduct any editing experiments in the sandbox.
 * If you're a Wikipedian, see Wikibooks for Wikipedians for a primer on how things work here (it's a little different).
 * If you want to base your work here on materials from Wikipedia, please use WB:RFI to bring the material over in compliance with the GFDL.
 * If you're an instructor and plan on using wikibooks for a class project, see Guidelines for class projects
 * Please say hello at the Staff Lounge with any questions or ideas.
 * Eventually, you might want to read the Manual of Style and Policies and Guidelines.
 * Please take a look at Naming policy before starting a new book.
 * Remember to maintain a Neutral point of view.
 * Explore, be bold in editing pages, and have fun!

You will find more resources in Community Portal. If you want to ask a question, visit the Study help desk, the Staff lounge, IRC channel or ask me personally on my talk page.

Good luck! -- Herby talk thyme 09:21, 8 November 2006 (UTC)

Page for deletion
You marked Movie Making Manual-Film Academy Training for speedy deletion (I completely agree). However it has been taken to a vote at - Votes_for_deletion - I guess you may wish to make your views know. Regards -- Herby talk thyme 09:23, 8 November 2006 (UTC)

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Miketm. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Miketm~enwikibooks that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

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

title: User talk:Miketm~enwikibooks


text:
Basic Physics of Nuclear Medicine/MRI & Nuclear Medicine

This is a developing chapter of a wikibook entitled Basic Physics of Nuclear Medicine.

Magnetic resonance imaging (MRI) is widely used to provide colocalization information for correlative applications with nuclear medicine images. An introduction to this imaging method is provided in this chapter. We'll consider fundamental features to a depth sufficient to describe the contrast and spatial characteristics of MR image data so that spatial correspondence features with nuclear medicine data can be appreciated. Since MRI is such a vast field, we'll limit our treatment to a description of essential features only and you should refer to the Bibliography for more comprehensive accounts.

We'll start with an overview of the imaging process and then describe magnetic resonance features of the simplest atomic nucleus known, i.e. 1H. From there we'll describe phenomena which generate contrast in MR images and finish with a description of image formation using spatial encoding techniques.

MR Imaging Process
In principle, MRI is quite a simple imaging technique, as illustrated in the animated graphic below. A patient is first of all placed inside a large magnet – the poles of which are indicated by the N and S boxes in the figure. Radio waves are then used to excite the nuclei of hydrogen atoms within the patient's body using an external coil and these are subsequently re-emitted by the patient in a manner which is characteristic of the NMR properties of the tissues involved. These radio waves are detected using an external coil, digitized, processed by a computer and displayed as tomographic slices revealing the distribution of different tissues.

The imaging process is a bit more complex in practice, as indicated in the following figure:

The complexity arises from the use of gradient magnetic fields and sophisticated radio wave excitations so as to provide spatial localization information for the subsequent detection phase, and to isolate a particular NMR characteristic of interest. One powerful feature of MRI is that the method can generate images depicting a number of different contrast characteristics. Three such image types are shown as examples below:

The physics behind the production of these types of images is briefly described in this chapter. We'll start with some insights into the nature of nucleons which we have not considered previously in this wikibook.

Nuclear Spin
Our earlier consideration of the atomic nucleus concentrated on its composition in terms of the mass, electrical charge and the relative number of its neutrons and protons – the intention being to introduce the phenomenon of radioactivity. We neglected to mention, for the sake of simplicity, that nucleons can be considered to spin in space around a central axis. We'll now concentrate on this spinning characteristic in order to introduce the phenomenon of nuclear magnetic resonance (NMR), and we'll see later how images can be formed on this basis.

Let's take an isolated proton as an example – see the following figure:

Besides having an electrical charge, the proton also spins on its axis. Since this spinning constitutes a moving electrical charge (i.e. rotating around a central axis), a magnetic field is generated, as illustrated, similar to that generated by a bar magnet – but on a much smaller scale, of course. This spinning magnet aligns itself with any external magnetic field.

There's an additional feature to this rotation, however, called precession, which can be seen in many rotating objects, as illustrated by the spinning gyroscope below:

The rate of proton precession is what's important in NMR and has an angular frequency referred to as the Larmor frequency. Its specified by the gyromagnetic ratio of the nucleus in question and for hydrogen it has a value of 2.68x108 rad/s/T. This ratio implies a rate of 42.58 million precessions per second when a hydrogen nucleus is placed in a magnetic field of strength 1 Tesla, i.e. rather higher than that for the precession shown in the animation above!

The following equation is of relevance here:

f = γ Bo

where f is the precessional frequency, γ is the gyromagnetic ratio and Bo is the strength of the magnetic field. This is a very important relationship in NMR and is exploited in numerous ways in MRI, as you will see below.

Clinical MRI scanners typically use field strengths between 0.1 and 3 T depending on the application. The strength of the earth's magnetic field in comparison is about 50 μT, i.e. about 2,000 to 60,000 times smaller, while that of a magnetic door lock is about 0.1 T.

We've just considered the situation for an isolated proton in a magnetic field. An interesting phenomenon occurs when many billions of protons, in a sample of tissue for example, are placed in a magnet:

 * some of the protons line up in parallel with the field and some line up against it.

These two states are referred to as parallel and anti-parallel states, as illustrated in the following figure:

The above figure also indicates that the two alignments are equivalent to two quantum energy states separated by an energy difference, ΔE. More nuclei occupy the lower energy than the higher energy state, but their excess is incredibly small – less than 0.001%. Its enough, however, to exploit in NMR!

This energy difference is directly related to the precessional frequency through the following equation:

ΔE = h f

where h is Planck's Constant and f is the precessional frequency, related to the Larmor frequency, ω, through:

ω = 2 π f

The important point here is that:

 * transitions from the parallel to the anti-parallel state can be induced in the sample when it is excited with electromagnetic radiation of energy, ΔE.

This energy is about 1.75x10-7 eV for a proton in a 1 T field, i.e. a tiny amount of energy compared with electron binding energies, for instance. Compared to a 140 keV gamma-ray emitted by 99mTc, its energy is over a million, million times smaller.

The energy difference is equivalent to the energy of electromagnetic radiation in the radio frequency (RF) region of the electromagnetic spectrum, as illustrated below:

So, if we had a tissue sample placed in a magnetic field of 1 T and we beamed in radio waves at 42.58 MHz, we can expect to excite protons from the parallel to the anti-parallel state. This phenomenon is the resonance feature of NMR.

Its what happens following excitation that's exploited in MRI:

 * transitions back to the parallel state occur spontaneously over a time period which is characteristic of individual tissues and their various pathological conditions.

These transitions cause electromagnetic radiation to be emitted from our tissue sample whose amplitude decreases with time. The detected emissions form what is called a Free Induction Decay, as illustrated below:

Its the time constant of signal decays such as these which is determined in MRI and which can be encoded into MR images – once we've figured out where within the patient the signals have originated from.

Magnetic Sum Vector
Its useful before proceeding to consider the situation from a magnetic vector perspective, as illustrated in the following figure:

The figure shows the situation for a hypothetical tissue sample placed in a magnetic field such that seven hydrogen nuclei are in the parallel state and five are in the anti-parallel state. Five of the parallel vectors cancel the effects of the five anti-parallel vectors and we're left with a net condition of two parallel vectors. We can simplify the situation further by considering the summation of these two vectors to give us a magnetic sum vector along the Z-axis, as illustrated in the following diagram:

Since the magnetic field direction is generally along the Z-axis in MRI, our magnetic sum vector is referred to as Longitudinal Magnetization. As a result, a longitudinal magnetization becomes established when a patient is placed inside the magnet of an MRI scanner.

RF Excitation
Let's consider the situation once longitudinal magnetization has become established and when a pulse of RF radiation at the resonant frequency is beamed into our tissue sample, as illustrated in the following diagram:

Two processes occur simultaneously during absorption of the radiant energy:

 * Reduction in Mz: Some of the protons resonate and move to the anti-parallel state, resulting in a reduction in the longitudinal magnetization, as illustrated below:

 * Notice that our initial situation with five protons aligned parallel, which gives rise to a longitudinal magnetization, Mz, of relatively large magnitude, changes to one where three are left with this alignment and two with the anti-parallel alignment. The magnitude of Mz is reduced as a result.

 * Phase Coherence: the vectors align with each other in phase, as illustrated below:

 * The outcome of phase coherence is the establishment of a magnetic sum vector in the X-Y plane, called the Transverse Magnetization.

So, once longitudinal magnetization is established by placing a patient in the magnet of an MRI scanner and radio waves at the resonant frequency are generated, we in effect establish a transverse magnetization while reducing the longitudinal magnetization. Its what happens next to these two magnetic sum vectors, Mz and Mxy, that's of interest in MRI.

RF Emission
We can consider the emission phase of the MR imaging process from both the longitudinal as well as the transverse magnetization perspectives. Since the protons in our tissue sample have been excited by the absorption of RF energy at the resonant frequency, the emission phase corresponds with what is called relaxation as protons return to their lower energy state.

 * Longitudinal Relaxation

 * The situation following excitation is illustrated in the top left panel of the following figure:

 * A hypothetical situation is shown where four protons are aligned parallel to the external magnetic field, and four excited protons are aligned anti-parallel. The magnetic sum vector is zero at this stage. Excited protons then return progressively to their lower energy state, as shown by the other panels in the above figure.  The result is a re-establishment of the longitudinal magnetization, Mz, as illustrated in the following figure:

 * It is seen in this figure that the longitudinal magnetization becomes re-established in an exponential manner characterized by a time constant, called T1.

 * Transverse Relaxation
 * The situation following excitation is illustrated in the top left panel of the following figure, with phase coherence taken into account. As a result, a transverse magnetization, Mxy becomes established:

 * A hypothetical situation is illustrated where three protons are aligned parallel and three anti-parallel, in phase coherence with each other. The other panels in the figure illustrate a progressive loss of coherence that is characterized by this form of relaxation, where the transverse magnetization decreases to zero, as shown in the following figure:

 * It is seen in this figure that the transverse magnetization decreases in an exponential manner characterized by a time constant, called T2* – also called T2 Star.

In case you're wondering about phase coherence at this stage, a good analogy to think of is that of analogue time clocks in different parts of the world. You may have seen such clocks on international TV news programmes showing the time in different parts of the world or in foreign exchange banks, for instance. Dublin, Sydney, New York and Mumbai, for example, all have clocks which take 60 minutes for one revolution of the big pointer. Their frequencies are identical, in other words. But they each show times separated by several hours because of their geographic location and daylight saving factors. We can conclude that these clocks are out of phase with each other, even though their frequencies are the same. However, all clocks located in Sydney, for example, would have the same phase and we can say that they are in phase coherence. In a similar manner, phase coherence of proton precessions results during RF excitation in NMR and its the loss of this coherence which happens in transverse relaxation.

So, what do these two time constants, T1 and T2*, mean in terms of our tissue sample?

The protons which generate NMR signals are primarily those in cellular fluids and lipids, i.e. nuclei of hydrogen atoms that are relatively free to move within their environment. Hydrogen protons in tightly-bound environments such as within proteins or DNA, however, usually do not contribute to NMR signals and the same situation exists for those in solid structures such as bone.

We can first of all consider a water molecule moving through its environment within our tissue sample as a result of local chemical and physical forces. The magnetic properties of its two hydrogen protons generate a small magnetic field of about 1 mT and the molecule's motion is therefore also influenced by the magnetic properties of other water molecules in its vicinity – and it in turn influences their motion. When excited protons are involved following RF excitation, it is interactions with their local environment which cause them to loose their excess energy and return to the lower energy state with the emission of RF radiation. This can be considered to be the origin of the re-establishment of longitudinal magnetization during relaxation. Chemistry calls this phenomenon spin-lattice relaxation – spin referring to the spinning proton and lattice to its local environment.

The rate at which molecules can move within their environment is related to their size and hence small molecules have a low probability for interaction. This is why fluids such as CSF have long T1 values, for instance – see the table below. Medium-sized molecules (e.g. lipids), in contrast, move more slowly, have a greater probability for interaction as a result, and exhibit relatively short T1 values.

The T2* phenomenon results from the compounding effect of imperfections in the external magnetic field and from so-called spin-spin interactions. These latter are interactions where two nearby protons can cause each other to flip so that one changes from anti-parallel to parallel alignment, while the other changes from parallel to anti-parallel, i.e. one gains the excitation energy from the other. Phase coherence with other excited protons is lost during this exchange and the end result is a relaxation of the transverse magnetization. This spin-spin interaction is also called T2 relaxation. It tends to happen much more rapidly than T1 relaxation and T2 values are therefore generally less than T1 values, as shown in the following table:

Since T2 arises mainly from neighbouring protons, a higher interaction probability exists with larger than with smaller molecules. Macromolecular environments will therefore display shorter T2 values than water-based fluids, e.g. CSF.

A final point to note is that both T1 and T2 measurements from a small volume of tissue result from the integrated motional effects of all molecular species which contain hydrogen protons in that volume, be they those of small molecules, lipids or macromolecules.

Inversion Recovery
A practical problem arises when we try to measure T1 because Mz exists within the Z-axis of the patient. If we could flip the longitudinal magnetization vector into the XY plane, then T1 could be measured using external coils. This is what the Inversion Recovery imaging technique is designed to do.

It involves a two stage excitation process, where an RF pulse of sufficient duration to excite all the lower energy protons is applied initially and this is followed by a second RF pulse after a time interval of duration sufficient for similar numbers of protons to exist in the two alignments. The first stage is illustrated in the following figure:

The RF pulse in this case is referred to as a 180o pulse since the longitudinal magnetization, Mz, has been inverted during the excitation process.

Then a short time interval is used to allow some longitudinal relaxation to occur, as illustrated in the following figure:

Notice that Mz recovers relatively slowly when the T1 of the tissue in question is relatively long, and that it recovers quite quickly when T1 is short. We can conclude that the extent of the recovery is related to T1.

A 90o RF pulse is then used to move Mz into the XY plane so that its amplitude can be measured, as shown in the next figure:

The sequence of RF pulses is shown in the left panel of the figure below, separated by the time interval, TI, and the resultant Free Induction Decay (FID) is shown below it. The amplitude of the FID is dependent on the relative values of T1 and the time interval, TI. For instance, when the time interval is less than T1, the longitudinal magnetization can still be negative when the 90o is applied – as we saw in an earlier figure. At the other extreme, when the time interval is much greater than T1, the longitudinal magnetization has sufficient time to fully recover and the amplitude of the FID is dependent primarily on the proton density.

The figure in the right panel below shows the dependence of the longitudinal magnetization measured from the FIDs of grey matter and CSF against the time interval, TI. It is seen that both substances generate a negative value of Mz when the time interval is short, as we might expect. It is also seen that Mz increases in each case when the time interval is increased and a region is reached where the values are strongly dependent on T1. It is further seen that a large difference can exist between the measured values for our two substances in this region. This feature gives rise to the generation of contrast between these two substances in T1-weighted images. Typically a time interval of 400 ms is used for such tissue discrimination.

A final point to note is the proton density-weighting that results when long time intervals are used, with little tissue discrimination. Typically an interval of 700 ms is used for such studies.

There are numerous other pulse sequences used besides Inversion Recovery in MRI. These include:
 * Spin Echo
 * Saturation Recovery
 * Short TI IR (STIR)
 * Echo Planar Imaging
 * Small Angle Gradient Echo (SAGE).

The Spin Echo sequence, for instance, can be used to generate a T2-weighting in images. You'll remember from earlier that an FID decays exponentially with a time constant, T2*. This parameter results from the combined effect of two phenomena:

 * static and oscillating magnetic fields induced by neighbouring protons (and unpaired electrons!) which we've discussed earlier and which generate the T2 information;

 * small imperfections in the primary magnetic field, Bo, which are referred to as field inhomogeneities, and generate a time constant, Tinh.

These two time constants can be considered to add, such that:

$$\frac{1}{T2^*} = \frac{1}{T2} + \frac{1}{T_{inh}}$$

and the function of the Spin Echo pulse sequence is to disentangle this relationship to extract the T2 information. Note that this pulse sequence can also be used to generate images with a T1 or a proton density weighting depending on various time intervals used in its pulse sequence.

The further treatment of Spin Echo and other pulse sequences is beyond the introductory level of this chapter and you are referred to the Bibliography for additional learning resources. However, you're likely to find that the treatment above will provide a sufficient foundation for developing your understanding of these other pulse sequences.

You might also like to check out the superb e-MRI online learning resource

Spatial Localization of NMR Signals
Since we've seen above how contrast between tissues can be generated in MRI we're now in a position to consider how images are formed. In other words, we'll consider how to localize the origin of the FIDs generated within the patient following RF excitation.

Its helpful to consider an analogy at this stage because this imaging situation is distinctly different to that encountered in nuclear medicine, radiography or sonography where the radiation travels in straight lines and imaging techniques based on emission, transmission and reflection can be readily conceptualized. Its a little bit more difficult in MRI because the radiation is emitted in all directions simultaneously, so that there's little or no chance in knowing its origin from an FID measurement. In other words, the FID only allows the amplitude, frequency and phase of the radio waves to be measured.

The analogy we'll use is that of a piano keyboard and the playing thereof. Let's imagine a concert pianist, for instance, on stage and playing the keyboard of a grand piano. Notice that the pianist's fingers hit keys to the left of the keyboard in order to produce a relatively low frequency (i.e. low pitch) sound, keys on the right for high frequency notes and keys in the middle for intermediate frequencies. So, besides hearing the music produced while the pianist plays, we also receive information about where in space the pianist's fingers were located at any individual moment. In technical jargon we can say that we are using a method of spatial localization through frequency discrimination of audio signals to determine locations along the piano's keyboard. This same approach can be applied in MRI using frequency discrimination techniques for the spatial localization of radio signals.

The 3D situation is of course a bit more complex than the 1D piano keyboard, but the principle is basically the same. Frequency discrimination can be achieved by arranging for RF emissions from the patient to have slightly different frequencies depending on their origin. Furthermore, phase discrimination can also be applied so that the phase of the RF emissions can be related to locations within the patient. The fidelity of the frequency and phase discrimination should of course be sufficient so that the corresponding voxels within the patient are sufficiently small enough for clinically-useful views of the anatomy to be generated. Afterall, the fidelity of our frequency discrimination in the case of a piano keyboard is limited at an extreme by the width of the keys!

The magnetic field of the magnet in an MRI scanner is therefore supplemented by small fields introduced using gradient coils so that a linear gradient, for instance, in the field can be established. With such a gradient applied along the patient's Z-axis, we can expect the resonant frequency of hydrogen protons to be different for planes along this axis, as illustrated in the following figure:

Should we wish to excite a single slice along this axis, for instance, all we need to do is generate radio waves of the relevant frequency, as dictated by our earlier equation:

f = γ Bo.

This approach is called slice selective excitation. Both the strength of the gradient field and the bandwidth of the RF pulse produced by the transmitter can influence the thickness of the selected slice as indicated in the following figure:

We can see in the left panel above that increasing the gradient in the magnetic field from Ga to Gb, for instance, decreases the slice thickness, ΔZ, when the bandwidth, Δf, is kept constant. In comparison, we can see in the right panel that increasing the bandwidth of the RF pulse generated by the transmitter circuitry, from Δfa to Δfb for instance, increases the slice thickness.

It is important to note that the slice selection gradient is applied during the application of the RF excitation pulses. The protons in any given plane can then be made to resonate by changing the RF pulse centre frequency, fo, during the scan.

The Gz gradient and the RF bandwidth control the slice thickness and position in this manner. Note that although the slice selection gradient has been described here in terms of the Z-axis, there is no reason in principle why any other directions cannot be chosen for the application of the gradient. The slice selection is therefore not governed by mechanical considerations, as is the case in X-ray CT, SPECT and PET.

One method of tomographic imaging based on this approach is considered next. Let's assume for simplicity that our patient can be represented by an elongated cube, as shown in the following figure:

Notice that our patient is placed in a magnet with a longitudinal gradient in the field, as illustrated by the blue line. The field strength is relatively low, as a result, towards the left of our cube and relatively high towards the right. A central slice of the cube can be excited when an RF pulse of the appropriate frequency is applied. Suppose the selected slice contains two features which generate FIDs, as indicated by the red and green objects.

The RF pulse is used to excite protons in this slice so that they all precess at the same frequency. A transverse gradient in the magnetic field is then applied during the emission phase, as illustrated in our next figure, so that the field strength is low, for instance, to the left of the selected slice and higher to the right of the slice. Precessional frequencies will therefore increase, decrease or remain the same depending on their horizontal location across the slice. The emitted FIDs will therefore contain a range of frequencies which represent this horizontal location.

The frequency content of the FIDs can be unscrambled by computing the one-dimensional Fourier transform, as illustrated in the figure above, to derive the horizontal spatial locations of the emitters. The resultant Fourier spectrum constitutes one projection, somewhat similar to that acquired in X-ray computed tomography. The subsequent steps are to generate projections at different angles around the slice by repeating steps 1 and 2 in the above figure using different transverse gradients. A series of projections can then result which can be processed using Filtered Back Projection to form an image of the axial slice.

This method is rather slow for clinical application and numerous other methods have been devised. We've considered it here simply because its a good exercise in integrating many of the features that you've learnt about in this chapter and because of its relative simplicity. Faster image acquisition times can be generated using the so-called Spin Warp method, for example. Here, a two-dimensional Fourier transform is applied using repeated slice selective excitations along with frequency-encoding gradients (as we've just described) as well as phase-encoding gradients during the emission phases.

Back to the Nucleus
There are many other features of MRI that are beyond the scope of this chapter. Issues such as safety in magnetic environments are of vital importance and features such as magnetic resonance angiography (MRA), magnetic resonance spectroscopy (MRS), Diffusion Tensor Imaging (DTI), functional MRI (fMRI), contrast media, image artefacts as well as magnet design, shielding and siting are fascinating to consider from a nuclear medicine perspective.

We'll conclude this chapter with an important basic feature which we didn't consider earlier in the interests of clarity. This brings us back to the nucleus and the topic of nuclear spin. You'll appreciate that its not just the hydrogen proton that demonstrates the NMR phenomenon and that it can occur, at the least, in situations where the nucleus has an odd number of protons. In other words, situations where there's an isolated proton which does not have a partner to pair with magnetically in its nucleus.

There's actually three types of nucleus where nuclear spin is concerned – those with:

 * Odd Mass Number, i.e. nuclei with one unpaired nucleon;

 * Even Mass Number & Even Atomic Number, i.e. nuclei with no unpaired nucleons;

 * Even Mass Number & Odd Atomic Number, i.e. nuclei with two or more unpaired nucleons.

Examples of nuclei with a net nuclear spin are given in the following table:

Only 1H has found application in routine medical imaging because of the vast quantity of water in the human body.


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Talk:ZK/How-Tos/HowToSetupEclipseWtpForZK

Original Text
thats it... please adapt and extend this description, since i'm not very experienced with ZK until now... --Oberinspector 16:55, 16 March 2006 (UTC)

The easiest way to get code completion for me was just to copy this fragment into a new zul-file:    Thats enough for me and eclipse, Tom.

Content
It can be expected that the ZK tutorial is followed. So, the code completion fragment is redundant.

What remains to be done? MrQuincle 10:53, 8 November 2006 (UTC)


text:
User talk:75.18.197.144

Welcome to Wikibooks. We invite everyone to contribute constructively to our collection. Take a look at the welcome page if you would like to learn more about contributing. However, unconstructive edits are considered vandalism, and if you continue in this manner you may be blocked from editing without further warning. Please stop, and consider improving rather than damaging the hard work of others. Thanks. -- Herby talk thyme 11:27, 8 November 2006 (UTC)

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Quenya/Perfect Tense

Regular formation
This tense is formed in the following way:
 * Repeat the central vowel of the verb and put it in front of it,
 * Lengthen the central vowel, if possible,
 * Add the ending -ië (  -ier in the plural).

So we find e.g.
 * mat- "eat" →  amátië

 * tec- "write" → etécië

 * not- "count" → onótië

The A-verbs and U-verbs lose their final vowel before adding -ië:
 * mapa- "take" → amápië

 * palu- "spread" →  apálië

Verbs with long central syllable
Verbs with a central vowel that cannot be lengthened are divided into three types:
 * When the stem ends in a consonant-cluster, we cannot lengthen the central vowel, but otherwise the basic rule is followed:
 * nasta- "prick" → anastië

 * nurru- "grumble" → unurrië

However, menta- and  fanta- have attested perfect  eménië and  afánië,

While orta- and  henta- have  ortanië and  ehentanië.

 * When the central vowel is long, we put a short version of this vowel in front of the stem:
 * móta- "labour" → omótië

 * When the central vowel is a diphthong, we add the first vowel of the diphthong:
 * hauta- "stop" → ahautië

 * poita- "cleanse" → opoitië

 * vaita- "wrap" → avaitië

 * suila- "greet" → usuilië

 * tiuta- "fatten" → itiutië

Verbs starting in a vowel
When the verb starts in a vowel, we don't add an extra vowel to the beginning of the stem:
 * anta- "give" → ánië

 * allu- "wash" → allië

 * ulqua- "rend" → ulquië

 * ita- "sparkle" → ítië

Verbs with a prefix
Some verbs are formed by placing a prefix before another verb, in this case we first form the perfect tense of the original verb and then we put the prefix again in front:
 * enyal- "recall" → en + ayálië →  enayálië

Verbs on -ya
Verbs on -ya lose both these letters:
 * hanya- "understand" → ahánië

 * tulya- "lead" → utúlië

Some ancient verbs end on a diphthong followed by -tya, they probably follow the same rule as the others:
 * paitya- "repay" → apaitië

Some verbs have a vowel before the ending -ya.

Possibly the perfect can be formed by the insertion of an -n- between the stem and the ending:
 * aya- "honour" → ánië

 * laya- "flourish" → alánië

 * naya- "grieve" → anánië

 * paya- "punish" → apánië

 * vaya- "enfold" → avánië

 * oya- "salve, rub" → ónië

 * loya- "be thirsty" → olónië

 * séya- "appear, seem" → esénië

 * súya- "breathe" → esúnië

 * ahya- "change": as is mentioned on the page about Quenya/Phonology, the combination hy has to be seen as a unit, so the perfect tense is probably  ahyánië

Some verbs can be conjugated by using an ancient stem and don't need an extra n
 * feuya- "abhor" → efévië (ancient stem  phew)

 * mauya- "compel" → ambávië (ancient stem  mbaw, see also below: historical influences)

 * tiuya- "swell" → itíwië (ancient stem  tiw)

The verb tuia- comes from the ancient stem  tuy, so the perfect tense would also need  n:
 * tuia- "sprout" → utúnië

Historical influences on the perfect tense
Most likely certain verbs undergo historical influences. The problem can be found in the prefixed vowel. Quite a few letters are allowed in the middle of a word but not in the beginning, so they have evolved differently in the perfect tense.

In most verbs there is no problem because they begin in a letter that is allowed in both places: tul- "come" has  utúlië "has come" as perfect tense.

In Primitive-Elvish this verb was tul and there is no problem here because t is allowed at the beginning of a word

(note: the Passive infinitive shows the same irregularities as a prefixed a- has the same effect).

Verbs in d-
Take now the Primitive-Elvish verbs 'dant' "fall" and  'dab' "allow". The letter d is no longer a separate letter in Neo-Quenya, neither in the beginning nor in the middle of a word. In the evolution a d in the beginning of a word changed into an l and in the middle of a word it changed into  r.

So these verbs evolved into the Quenya verbs lanta- "fall" and  lav- "allow"

(the b changed into v but here there is no problem as this letter never appears at the end of a word).

But in the perfect tense the d changed into r:
 * lanta- "fall" → arantië

If we apply this to lav- we get a nice consequence: Primitive-Elvish also had a verb  'lab' "lick".

In Quenya this verb also evolved into lav-, but their perfect tenses have remained different:
 * lav- "allow" → arávië

 * lav- "lick" → alávië

Verbs in mb- / nd- / ng-
These verbs are however not the only ones, in Primitive-Elvish we had verbs that began with the consonant clusters mb-,  nd- or  ng-. In Quenya these are no longer allowed in the beginning of a word, but in the middle of words they are still allowed.

The verbs namba- "hammer" and  núta- "set (of sun and moon)" have evolved from the Primitive-Elvish stems  'ndam' and  'ndú'.

So in the perfect tense we find:
 * namba- "hammer" → andambië

 * núta- "set" → undútië

The next verbs show Primitive-Elvish forms to Quenya, then to their perfect tenses:
 * 'mbar' → mar- "dwell" →  ambárië

 * 'mbakh' → manca- "trade" →  ambancië

 * 'mbarat' → martya- "destine" →  ambartië

 * 'mbas' → masta- "bake" →  ambastië

The verbs beginning with ng- can in Tengwar script can still be recognised, as they are still written with the Tengwar  ñoldo or ngoldo (Tengwa 19).

In Exilic Quenya pronunciation, there is no difference between ñoldo and the normal  n (númen). Because of this, they can be written with either characters and both forms are acceptable. Note that can only be written as an initial consonant of a word only.

At the moment we know two verbs in this category:
 * 'ngol' → nol- "smell" →  ongólië

 * 'nganad' → nanda- "harp" →  angandië

Verbs in h-
Verbs beginning with h- can show the same problems because this  h could have evolved from either  'kh'- or  'sk'-.

This last combination gives in Neo-Quenya the letter h at the beginning of a word and an  x in the middle of a word.

Here we have following verbs and perfect tenses:
 * 'skal' → halya- "hide" →  axálië

 * 'skar' → harna- "wound" →  axarnië

 * 'skat' → hat- "split" →  axátië

 * 'skel' → helta- "undress" →  exeltië

When this starting h appears in the combinations hy-, hl- or hr- then we find following forms:
 * hyar- "cleave" → aryárië

 * hlar- "hear" → allárië

 * hranga- "thwart" → arrangië

In the combination hw- the changes are like these:
 * hwesta- "breathe" → eswestië

 * hwinya- "swirl" → iswínië

Verbs in -s- / -þ-
The final irregularity is found with verbs starting in s. This s can either be a pure s (Tengwa 29 & 30 silmë & silmë nuquerna) or have evolved from  th (Tengwa 9 thúlë / súlë). The only irregularity is within how it can be written in Tengwar.

Words derived from thúlë/súlë can be written with either  thúlë/súlë or with  silmë / silmë nuquerna in Tengwar, but words that originally came from an "s" are never written with  thúlë/súlë and only with  silmë / silmë nuquerna.

Derived from -s-:
 * salpa- "sip" → asalpië

 * ser- "rest" → esérië

 * sil- "shine" → isílië

 * sir- "flow" → isírië

 * suc- "drink" → usúcië

Derived from -th- / -þ-:
 * vasarya- "veil" → avasárië

 * vaþarya → avaþárië

>> Neo-Quenya >> ../Verbs/ >> ../Perfect Tense/

title: Quenya/Perfect Tense


text:
User talk:213.249.155.246

Thanks for experimenting with Wikibooks. Your test worked, and has now been removed. Please use Sandbox for any other tests you want to do, since testing material in modules will normally be removed quickly. Please see the welcome page if you would like to learn more about contributing to our project. Thanks. -- Herby talk thyme 12:16, 8 November 2006 (UTC)

title: User talk:213.249.155.246


text:
Template:Pestprof

To start a new profile page for a pest, add to the page, then save.

This template should always be substituted. The included templates pestbox and pestcontrol should never be substituted. /Templates/Profiles Introductory notes go here: common names, general type, native and adopted range.

Description
Physical description of the pest.

Symptoms and Signs
Damage done by the pest.

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Bulleted, linked list.

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A-level Chemistry/AQA

This is the branch of the A-level Chemistry book, designed to follow the AQA specification. It is not endorsed by AQA. It will hopefully be useful as a revision guide, or for those seeking a basic grounding in the principles of the course.

AS Units

 * Module 1: Atomic Structure, Bonding and Periodicity
 * Atomic Structure
 * Amount of Substance
 * Bonding
 * Periodicity
 * Module 2: Foundation Physical and Inorganic Chemistry
 * Energetics
 * Kinetics
 * Equilibria
 * Redox Reactions
 * Group VII: The Halogens
 * Extraction of Metals
 * Module 3: Introduction to Organic Chemistry
 * Nomenclature and Isomerism
 * Petroleum and Alkanes
 * Alkenes and Epoxyethane
 * Haloalkanes
 * Alcohols

AS Chemistry Specification, 2007 Entry

A2 Units

 * Module 4: Further Physical and Organic Chemistry
 * Kinetics
 * Equilibria
 * Acids and Bases
 * Nomenclature and Isomerism in Organic Chemistry
 * Compounds Containing the Carbonyl Group
 * Aromatic Chemistry
 * Amines
 * Amino Acids
 * Polymers
 * Organic Synthesis
 * Structure Determination
 * Module 5: Thermodynamics and Further Inorganic Chemistry
 * Thermodynamics
 * Periodicity
 * Redox equilibria
 * Transition metals
 * Reaction of inorganic compounds is aqeueous solution

title: A-level Chemistry/AQA


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A-level Chemistry/AQA/Module 1/Atomic Structure

The Atom
The Greek Philosopher Democritus believed that all matter was made up of small indivisible parts, which he called atoms. The word atom comes from the Greek a, meaning not, or without, and tom, meaning to cut. Therefore, the word atom means: not cuttable. He theorised that if one cut a piece of cheese in half, then in half again, and again, and again, et cetera, one would be left with a piece too small to subdivide. This was his single atom.

We now know that an atom is the smallest part of something that retains its identity, although the atom itself can be subdivided. In other words, once we begin to look inside the atom, we can no longer tell which element the atom is.

The atom itself comprises a central nucleus, in which most of the mass is concentrated, with electrons orbiting around the outside of this nucleus. This central nucleus consists of protons and neutrons. The properties of these three kinds of particle are given in the following table.

In the neutral, or elemental atom there are equal numbers of protons and electrons. This causes the atom to have no overall charge.

Atomic Number and Mass Number
There are two useful pieces of information that we can glean from the nucleus of an atom. The first is its atomic number. This allows us to identify which element an atom is. The atomic number, usually denoted by the letter Z, is the number of protons in the nucleus of an atom. It is this which places an element in the periodic table.

The second is the mass number. This is equal to the number of protons, plus the number of neutrons (remember that electrons have negligible mass). It is given the symbol A.The number of neutrons in an atom, therefore, is equal to the mass number (A), minus the atomic number (Z)

Isotopes
Sometimes an atom's proton number will show that it is a particular element, and yet its mass number will be different to other atoms of that element. Atoms which have the same proton number, yet different mass numbers, are referred to as isotopes of the element. The difference in mass number is caused by the presence of extra, or fewer neutrons in the nucleus.

Since the number of protons (and, therefore, of electrons) is the same, the chemical properties of these materials are the same as those of the standard element. The physical properties (melting/boiling point etc.) DO change.

We usually refer to isotopes by the element name, followed by the mass number. For example, a carbon atom with a mass number of 12 (six protons, and six neutrons) is known as carbon-12. This is represented thus: $${}_6^{12}\!C$$

One of the most useful isotopes is carbon-14. This is the atom $${}_6^{14}\!C$$. It is radioactive, and can be used to determine the age of organic material as old as 60,000 years! Other isotopes are used in medicine as tracers, to determine the location of any blockages in the body.

Mass Spectroscopy
Mass Spectroscopy is a technique used to determine the relative abundance of various isotopes within a sample. It can be broken down into four stages.

1. Vaporisation and Ionisation The sample to be analysed is introduced into a vacuum chamber. The sample is vaporised. This is essential if the following stages are to succeed. The vacuum is very important, since the electrons which are to be fired at the sample must have a "clear run", so to speak. If they were not in a vacuum they would collide with air molecules.

The sample is now ionised. For this, an electron gun is used. This is, in essence, a device which fires high energy electrons into the sample. These electrons knock electrons in the sample out of orbit, ionising it. Particles in the sample are now positively charged, as shown below.

$$X_{(g)} \to X_{(g)}^+ + e_{(g)}^-$$

$$He_{(g)} \to He_{(g)}^+ + e_{(g)}^-$$

These two equations show the first ionisation stage. It is possible, however, for an ion to become ionised by a second electron. This is unlikely, since the second ionisation is much higher than the first, and unlikely to be reached. This rare event is represented by this equation:

$$X_{(g)}^+ \to X_{(g)}^{2+} + e_{(g)}^-$$

2. Acceleration

Since opposite electrical charges attract, we can move the particles using an electric field. The particles are positively charged (electrons have been removed) so we use negatively charged electrical plates to accelerate the particles down the machine.

3. Deflection

We now use an electromagnet to deflect the particles. As the particles accelerate through the magnetic field, they change direction. Particles with large mass-to-charge (m/z) ratios are deflected by small amounts, whereas particles with smaller mass-to-charge ratios are deflected by larger amounts. This separarates ions of different mass-to-charge ratios.

4. Detection

The various species in the sample are now separated. The particles accelerate into a detector plate. Since they are charged, upon hitting the plate a small electrical current is produced. This current is recorded. The relative strength of the magnetic field at the time of detection can be used to calculate the m/z value of the ions detected. This allows us to determine the constituent ions of the sample. It is not possible, however, to distinguish between ions of the same m/z value, since they will be equally deflected!

This page gives more information on mass spectroscopy: http://www.chemguide.co.uk/analysis/masspec/howitworks.html#top.

Relative Masses
The following two definitions are required to be learnt for module one, although they may appear esoteric at first.

Relative Atomic Mass ($$A_r$$)
$$A_r = \frac{\mbox{Mean Mass of One Atom} \times 12}{\mbox{Mass of One Atom of } {}_6^{12}\!C}$$

This can be calculated from the mass spectrum of a sample by multiplying each peak's m/z value by its relative abundance. This sum is then divided by the total relative abundance. This is shown below for the mass spectrum of boron, in which the two peaks represent $${}^{10}\!B$$ and $${}^{11}\!B$$ respectively.

$$\frac{(19.9 \times 10) + (80.1 \times 11)}{100} = 10.8$$

This can also be calculated from data in a table, as shown in this example for lead.

(It is important to note here that the relative abundances add up to 100.05, NOT 100.)

$$\frac{(1.55 \times 204) + (23.6 \times 206) + (22.6 \times 207) + (52.3 \times 208)}{100.05} = 207.24$$

Relative Molecular Mass ($$M_r$$)
$$M_r = \frac{\mbox{Mean Mass of One Molecule} \times 12}{\mbox{Mass of One Atom of } {}_6^{12}\!C}$$

This can be calculated from a mass spectrum by taking the m/z value of the peak furthest to the right of the graph, as shown in this example for ammonia.

Electronic Configuration
At GCSE level, electrons are presented as point like entities that orbit around the nucleus of the atom, with the first orbital being able to hold two electrons, the second eight, and the third eighteen. We now know that this is not strictly accurate, and at A level a more sophisticated model is required.

We think of the electron orbitals as inhabiting a sub-level within a principal level. Each sub-level is capable of containing orbitals of a single shape referenced by the letters s,p,d and f. The sub levels themselves are commonly referred to by the letter of the orbital type which they can contain. Instead of saying the 3rd sub level of principal level 4 you would say the d sub level of level 4.

In the table below you should be able to see that the third sub level (d) of principal level 3 can contain 5 orbitals of type d. As each orbital can contain up to 2 electrons this means that this sub level can contain 10 electrons.

As shown in the table, the maximum number of orbitals in each type of sub level is related to its type. An 's' sub level can contain only one orbital (2 electrons), a 'p' sub level con contain a maximum of 3 orbitals (6 electrons) ; a 'd' a maximum of 5 orbitals (10 electrons); and an 'f' a maximum of 7 (14 electrons).

The capacity of each principal level is the sum of the capacities of its sub levels. You should be able to see that the capacities of the principal levels equate to the more simple GCSE model of electron shells.

There are certain rules that it is necessary to know about the filling of these orbitals.
 * 1) The orbitals are filled in the order of the table, from top to bottom. This is in ascending order of energy; that is to say, each successive energy level (lower down the table) has higher energy than the previous level.
 * 2) Each orbital must be filled before electrons are put into the next orbital. An atom, for example, must always have two electrons in its 1s sub-energy level before any are placed into the 2s orbital.

For AQA A level chemistry you are required to be able to fill energy level diagrams to level 4s.


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Horticulture/Pest Trapping

Many garden pests can be controlled or monitored for using traps. Traps attract the pest using food scents, pheromones, colors, or a combination of these to attract pests.

title: Horticulture/Pest Trapping


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Horticulture/Physical Removal of Garden Pests

Many garden pests can be controlled by simply removing them from the plant. In some cases, they can be simply "squished", in others they can be pruned out or blasted off with high-pressure water.


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Horticulture/Pest Barriers

Pest Barriers are used in the garden to keep pest animals away from plants. Barriers include everything from electric fences (for large animals) to row covers (for flying insects) to kaolin sprays.

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Horticulture/Pest Repellents

Pest repellents keep pests away from plants (or in some cases people or pets), without necessarily being lethal to the pest.

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Horticulture/Pesticides

Pesticides are substances that are poisonous to garden pests.

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Horticulture/Organic Pesticides

Organic pesticides are pesticides that are acceptable in organic growing practices. As a rule, they are derived from botanical sources, unprocessed minerals, or are biological agents.

title: Horticulture/Organic Pesticides


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Horticulture/Alternate Hosts of Garden Pests

Garden pests often feed on plants other than just those being intentionally grown in gardens. Many weeds can act as alternate hosts for plant pests, so in order to control a serious infestation, it may be important to also either control the pests on the weed plants or simply remove the weed population.


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Horticulture/Predators and Parasites of Garden Pests

Effective control of many garden pests can be achieved by either attracting or introducing predators, parasites, and parasitoids.


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Horticulture/Micro-biocontrols

Micro-biocontrols are organisms that can be employed by gardeners to control garden pests and plant diseases.

title: Horticulture/Micro-biocontrols


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Horticulture/Pine Sawflies

The Pine Sawflies are a group of insects that eat the needles of various species of pine. They feed as larvae in large colonies. They are often mistaken for caterpillars, but like all sawflies they are actually closer relatives to wasps and bees rather than moths and butterflies.

Because of their colonial habit, they can cause severe damage to individual pine branches, completely stripping the foliage and leaving only unattractive branches. They tend not to eat the buds, however, so the branch tips usually leaf out afterwards.

Description
The larvae are generally greenish, found in large colonies. They "rear up" when a branch they are feeding on is disturbed, which is a defense mechanism that can scare off birds.

Ecology
Found on pines throughout the landscape, with some species being preferred over others. The adults are good fliers.

Host plants

 * Pines

title: Horticulture/Pine Sawflies


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Horticulture/Slugs

Slugs are gastropod molluscs without shells or with very small internal shells, in contrast to snails, which have a prominent coiled shell. The loss or reduction of the shell is a derived character, and the same basic body design has independently evolved several times, making slugs a polyphyletic group. Although they undergo torsion (180 degree twisting of internal organs) during development, their bodies are streamlined and worm-like, and so show little external evidence of it. Slugs include both marine and terrestrial species. The soft, slimy bodies of slugs are prone to desiccation, so land-living slugs are confined to moist environments.

Some species of slug are notable garden pests, and can cause considerable damage to both leafy vegetables (especially the brassicas) and "fruit vegetables" such as ../Tomato/es. There are various methods of controlling them. Best results may be achieved by combining several of the methods mentioned below.

Description

Slugs macerate food using their radula, a rough, tongue-like organ with many tiny tooth-like denticles.

Like snails, slugs have two pairs of 'feelers' or tentacles on their head. The upper pair--optical tentacles--are light sensors; the lower pair provides the sense of smell. Both pairs are retractable and can be regrown if lost. On top of the slug, behind the head, is the saddle-shaped mantle, and under this are the genital opening and anus. The mantle also has a hole, the pneumostome, for respiration. The slug moves by rhythmic muscular action of its foot.

Among the various species of land slug are the grey field slug, Deroceras reticulatus; the garden slug Arion hortensis; the leopard slug, Limax maximus; and the banana slug, Ariolimax columbianus.

Ecology
Most slugs eat leaves, fungus, and decaying vegetable material, but some are predators and most also eat carrion including dead of their own kind. Frogs, toads, snakes, hedgehogs, and some birds and beetles are natural slug predators. Slugs, when attacked, can contract their body, making themselves harder and more compact and thus more difficult for many animals to get a hold of. The unpleasant taste of the mucus is also a deterrent.

Slugs produce two types of mucus: one which is thin and watery, and another which is thick and sticky. Both are hygroscopic. The thin mucus is spread out from the centre of the foot to the edges. The thick mucus spreads out from front to back.

Mucus is very important to slugs as it helps them move around, and contains fibres which prevent the slug from sliding down vertical surfaces. Mucus also provides protection against predators and helps retain moisture. Some species use slime cords to lower themselves on to the ground, or suspend from them during copulation.

Slugs are hermaphroditic: having both female and male reproductive organs. Once a slug has located a mate they encircle each other and sperm is exchanged through their protruding genitalia. A few days later around 30 eggs are laid into a hole in the ground. Although some species hibernate underground during the winter in temperate climates, in other species, the adults die in the autumn.

A commonly seen practice among many slugs is apophallation, when one or both of the slugs chew off the other's penis. The penis of these species is curled like a cork-screw and often becomes entangled in their mate's genitalia in the process of exchanging sperm. Apophallation allows the slugs to separate themselves. Once the penis has been removed, the slug remains female for the rest of its life.

Various species of slug can also reproduce via tiny "darts" of sperm which they fling in the direction of their mate's genitalia.

Host plants
Slugs feed on a wide variety of garden plants, including strawberries and lettuce.

title: Horticulture/Slugs


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User:Muralinan

Inspired by open source and wiki, started involving myself with information that can be shared to make this world a better place to live. I am one of the believer of 'Live for others' and I try to help others in their need.

My Contribution
One of my main contribution is Project Management Institute (CAPM/PMP)

title: User:Muralinan


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XForms/Select and Group

Motivation
You want to conditionally display a group of elements based on the value selected from a list. This will work similar to a "switch/case" but you can have each view depend on complex XPath expressions that will evaluated to either true or false.

Screen Image

In the screen image above, the second item is selected. When a different item is selected, the view under the select list changes.

Sample Program
      Select View:   One one   Two</xf:label> <xf:value>two</xf:value> </xf:item> <xf:item> <xf:label>Three</xf:label> <xf:value>three</xf:value> </xf:item> </xf:select1> <xf:output ref="view-1"> <xf:label>Current view: </xf:label> </xf:output> <xf:output ref="view-2"> <xf:label>Current view: </xf:label> </xf:output> <xf:output ref="view-3"> <xf:label>Current view: </xf:label> </xf:output> <xf:group ref="view-1"> <xf:label>View One</xf:label> One One One One One One One One One One One One One One One One One One </xf:group> <xf:group ref="view-2"> <xf:label>View Two</xf:label> Two Two Two Two Two Two Two Two Two Two Two Two Two Two Two Two Two </xf:group> <xf:group ref="view-3"> <xf:label>View Three</xf:label> Three Three Three Three Three Three Three Three Three Three Three Three Three Three Three Three Three </xf:group>

Discussion
This program is very similar to the example that uses a button to toggle a switch/case but the value is calculated dynamically by any XPath expression. The prior example that uses switch/case/toggle uses an XML Event to make a specific case visible.

title: XForms/Select and Group


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XForms/Switch and Case

Motivation
You want to conditionally display different areas of the screen based on static IDs.

Screen Image

As you click on one of the three buttons on the top row, the view displayed below will change.

Link to XForms Application
Switch and Case

Discussion
XForms provides an easy ways to swap between views. This also shows how the XForms group and label can be used like the HTML fieldset and legend.

title: XForms/Switch and Case


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Horticulture/Cultural Controls

Cultural Controls are methods for garden pests, diseases, and weeds by altering the environment in a way that makes it an unsuitable habitat for the target organisms.

Controls include mulching or removing mulch, pruning to provide better air circulation, and companion planting.

Controls alter any one of the following:
 * Air circulation
 * Sunlight exposure
 * Soil chemistry, content, texture, and structure
 * Atmospheric and soil moisture

/Techniques

title: Horticulture/Cultural Controls


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Bartending/Cocktails/Polish Martini

Ingredients

 * 1 1/2 measures of Zubrowka vodka
 * 1 1/2 measures of Krupnik liqueur
 * 2 measures of Apple Juice

Garnish
none

Glass
cocktail glass

Procedure

 * 1) Take Zubrowka and Krupnik from the freezer
 * 2) Shake with crushed ice and strain the ingredients.
 * 3) Serve in an ice-cold 5oz Martini glass, no garnish.

title: Bartending/Cocktails/Polish Martini


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User talk:172.159.59.237

Thanks for experimenting with Wikibooks. Your test worked, and has now been removed. Please use Sandbox for any other tests you want to do, since testing material in modules will normally be removed quickly. Please see the welcome page if you would like to learn more about contributing to our project. Thanks. -- Herby talk thyme 16:21, 8 November 2006 (UTC)

title: User talk:172.159.59.237


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User talk:Kubbs17

Hello and welcome to Wikibooks!

Here are some tips to help you get started:
 * You can sign your name on Talk and vote pages using four tildes, like this: ~~~~.
 * Remember to conduct any editing experiments in the sandbox.
 * If you're a Wikipedian, see Wikibooks for Wikipedians for a primer on how things work here (it's a little different).
 * If you want to base your work here on materials from Wikipedia, please use WB:RFI to bring the material over in compliance with the GFDL.
 * If you're an instructor and plan on using wikibooks for a class project, see Guidelines for class projects
 * Please say hello at the Staff Lounge with any questions or ideas.
 * Eventually, you might want to read the Manual of Style and Policies and Guidelines.
 * Please take a look at Naming policy before starting a new book.
 * Remember to maintain a Neutral point of view.
 * Explore, be bold in editing pages, and have fun!

You will find more resources in Community Portal. If you want to ask a question, visit the Study help desk, the Staff lounge, IRC channel or ask me personally on my talk page.

Good luck! -- Herby talk thyme 16:22, 8 November 2006 (UTC)

title: User talk:Kubbs17


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Horticulture/Biological Pest Control

Biological control of pests and diseases is a method of controlling pests and diseases in agriculture that relies on natural predation rather than introduced chemicals.

Overview
A key belief of the organic gardener is that biodiversity furthers health. The more variety a landscape has, the more sustainable it is. The organic gardener therefore works to create a system where the insects that are sometimes called pests and the pathogens that cause diseases are not eradicated, but instead are kept at manageable levels by a complex system of checks and balances within a living and vibrant ecosystem. Contrary to more 'conventional' gardening practices which often use chemical methods to kill both useful and harmful garden life forms indiscriminately, this is a holistic approach that seeks to develop an understanding of the webs of interaction between the myriad of organisms that constitute the garden fauna and flora. The organic gardener will often hold the view for example that the eradication of the creatures that are often described as pests is not only not possible, but also undesirable, for without them the beneficial predatory and parasitic insects which depend upon them as food or hosts would not be able to survive.

In a healthy natural woodland where there is little direct human intervention, pest and disease organisms will always be present, but, unless there is a drastic environmental change, will normally kept in a state of equilibrium where they are not able to get out of hand to a level which is detrimental to the overall woodland community. This is the model for which the sensitive organic gardener will strive, but at the same time it is wise to recognise that there will often be some degree of intervention needed to manipulate the natural checks and balances to the gardener's favour, particularly if growing plants for food or ornament which would not normally occur in natural situations. Therefore biological control is about developing a range of techniques that use living organisms to maintain the beneficial equilibria in garden landscapes without causing adverse effects to humans or the wider environment. Of course, introducing exotic insects into any ecosystem entails taking risks of moving further from the intended equilibrium through unexpected interactions.

An important part of the biological gardening approach is to become familiar with the various life forms that inhabit the garden, predators as well as pests, and also their life cycles, patterns of feeding and the habitats that they prefer.

Insects have devised many ways to eat other insects. Predators will directly attack and devour their prey, whilst parasitoids will deposit an egg within another insects body, from which a larva will emerge which will devour the host's innards.

Examples of predators

ladybugs, and in particular their larvae which are active between May and July, are voracious predators of aphids, and will also consume mites, scale insects and small caterpillars. The ladybird is a very familiar beetle with red and black markings, whilst its larvae are initially small and spidery, growing up to 17 mm long. It has a tapering segmented grey/black body with orange/yellow markings nettles in the garden and by leaving hollow stems and some plant debris over-winter so that they can hibernate over winter.

../Hoverflies/ are another very welcome garden predator. Resembling slightly darker bees or wasps, they have characteristic hovering, darting flight patterns. There are over 100 species of hoverfly whose larvae principally feed upon greenfly, one larva devouring up to fifty a day, or 1000 in its lifetime. They also eat fruit tree spider mites and small caterpillars. Adults feed on nectar and pollen, which they require for egg production. Eggs are minute (1 mm), pale yellow white and laid singly near greenfly colonies. Larvae are 8–17 mm long, disguised to resemble bird droppings, they are legless and have no distinct head. Semi-transparent in a range of colours from green, white, brown and black. Hoverflies can be encouraged by growing attractant flowers such as the poached egg plant (../Limnanthes douglasii/), marigolds or phacelia throughout the growing season.

../Dragonflies/ are important predators of mosquitoes, both in the water, where the dragonfly nyads eat mosquito larvae, and in the air, where adult dragonflies capture and eat adult mosquitoes. Community-wide mosquito control programs that spray adult mosquitoes also kill dragonflies, thus removing an important biocontrol agent, and can actually increase mosquito populations in the long term.

Other useful garden predators include lacewings, anthrocorid bugs, rove and ground beetles, aphid midge, centipedes, predatory mites, as well as megafauna such as frogs, toads, hedgehogs, slow-worms and birds. Cats and rat terriers kill field mice, rats, June bugs, and birds. Dogs chase away many types of pest animals. Dachshunds are bred specifically to fit inside tunnels underground to kill gophers and rabbits.

Parasitic wasps
A diverse range of wasps lay their eggs on or in the body of an insect host, which is then used as a food for developing wasps. Parasitic wasps take much longer than predators to consume their victims, for if the larvae were to eat too fast they would run out of food before they became adults. Such parasites are very useful in the organic garden, for they are very efficient hunters, always at work searching for pest invaders. As adults they require high energy fuel as they fly from place to place, and feed upon nectar, pollen and sap, therefore planting plenty of flowering plants, particularly buckwheat, umbellifers and composites will encourage their presence.

Three of the most important groups are;

 * ../Ichneumon Flies/: (5–10 mm). Prey mainly on caterpillars.
 * ../Braconid Wasps/: Tiny wasps (up to 5 mm) attack caterpillars and a wide range of other insects including greenfly. A common parasite of the cabbage white caterpillar- seen as clusters of sulphur yellow cocoons bursting from collapsed caterpillar skin.
 * ../Chalcid Wasps/: Among the smallest of insects (<3 mm). Parasitize eggs/larvae of ../Aphids/, ../Whiteflies, cabbage caterpillars, ../Scale Insects/ and strawberry tortrix moth.

Plants to regulate insect pests
Choosing a diverse range of plants for the garden can help to regulate pests in a variety of ways, including;

Acting as trap plants by providing an alluring food that entices pests away from crops.
 * Masking the crop plants from pests, depending on the proximity of the companion or intercrop.
 * Producing olfactory inhibitors, odors that confuse and deter pests.
 * Serving as nursery plants, providing breeding grounds for beneficial insects.
 * Providing an alternative habitat, usually in a form of a shelterbelt, hedgerow, or beetle bank where beneficial insects can live and reproduce. Nectar-rich plants that bloom for long periods are especially good, as many beneficials are nectivorous during the adult stage, but parasitic or predatory as larvae. A good example of this is the soldier beetle which is frequently found on flowers as an adult, but whose larvae eat aphids, caterpillars, grasshopper eggs, and other beetles.

The following are plants often used in vegetable gardens to deter insects

 * Basil — Repels flies and mosquitoes.
 * Catnip — Deters flea beetle.
 * Garlic — Deters Japanese beetle.
 * Horseradish — Deters potato bugs.
 * Marigold — The workhorse of pest deterrents. Discourages Mexian bean beetles, nematodes and others.
 * Mint — Deters white cabbage moth.
 * Nasturium — Deters aphids, squash bugs and striped pumpkin beetles.
 * Pot Marigold — Deters asparagus beetles, tomato worm, and general garden pests.
 * Peppermint — Repels the white cabbage butterfly.
 * Rosemary — Deters cabbage moth, bean beetles and carrot fly.
 * Sage — Deters cabbage moth and carrot fly.
 * Southern Wood — Deters cabbage moth.
 * Summer Savory — Deters bean beetles.
 * Tansy — Deters flying insects, Japanese beetles, striped cucumber beetles, squash bugs and ants.
 * Thyme — Deters cabbage worm.
 * Wormwood — Deters animals from garden.

Directly introducing biological controls

Most of the biological controls listed above depend on providing incentives in order to 'naturally' attract beneficial insects to the garden. However there are occasions when biological controls can be directly introduced. Common biocontrol agents include parasitoids, predators, pathogens or weed feeders. This is particularly appropriate in situations such as the greenhouse, a largely artificial environment, and are usually purchased by mail order.

Some biocontrol agents that can be introduced include;
 * Encarsia formosa. This is a small predatory chaclid wasp which is parasitical on whitefly, a sap-feeding insect which can cause wilting and black sooty moulds. It is most effective when dealing with low level infestations, giving protection over a long period of time. The wasp lays its eggs in young whitefly 'scales', turning them black as the parasite larvae pupates. It should be introduced as soon as possible after the first adult whitefly are seen. Should be used in conjunction with insecticidal soap.
 * Red spider mite, another pest found in the greenhouse, can be controlled with the predatory mite Phytoseilus persimilis. This is slightly larger than its prey and has an orange body. It develops from egg to adult twice as fast as the red spider mite and once established quickly overcomes infestation.
 * A fairly recent development in the control of slugs is the introduction of 'Nemaslug', a microscopic nematode (Phasmarhabditis hermaphrodita) which will seek out and Parasitize slugs, reproducing inside them and killing them. The nematode is applied by watering onto moist soil, and gives protection for up to six weeks in optimum conditions, though is mainly effective with small and young slugs under the soil surface.
 * A bacterial biological control which can be introduced in order to control butterfly caterpillars is Bacillus thuringiensis. This available in sachets of dried spores which are mixed with water and sprayed onto vulnerable plants such as brassicas and fruit trees. The bacterial disease will kill the caterpillars, but leave other insects unharmed. There are strains of Bt that are effective against other insect larvae. Bt israelensis is effective against mosquito larvae and some midges.
 * A biological control being developed for use in the treatment of plant disease is the fungus Trichoderma viride. Trichoderma species are free - living fungi that are very common in root ecosystems. This has been used against Dutch Elm disease, and to treat the spread of fungal and bacterial growth on tree wounds. It may also have potential as a means of combating silver leafroo disease.

Economics of biological pest control
Biological control proves to be very successful economically, and even when the method has been less successful, it still produces a benefit-to-cost ratio of 11:1. One study has estimated that a successful biocontrol program returns £32 in benefits for each £1 invested in developing and implementing the program, i.e., a 32:1 benefit-to-cost ratio. The same study had shown that an average chemical pesticide program only returned profits in the ratio of 2.5:1.

title: Horticulture/Biological Pest Control


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Locksmithing

This how-to guide describes the techniques of lock picking.

Lock picking is an essential skill for a locksmith. It can also be an interesting skill to learn and can be useful to the householder. Lock picking is the ideal way of opening a lock without the correct key, while not damaging the lock, allowing it to be rekeyed for later use. This is especially important with antique locks that would be impossible to replace if destructive entry methods were used.

Usually it is possible to bypass a lock without picking it. Most common locks can be quickly and easily opened using a drill, bolt cutters, or a hydraulic jack. The hasp, door, or fixture they are attached to can be cut or broken. But lock picking is more rewarding than brute force.

Content

 * /Techniques/
 * /Key Impressioning/
 * /Tools/
 * /Legal Status/
 * /Further Reading/

title: Locksmithing