Generators info

In electronics (specifically, signal processing), half time usually refers to the time it takes for the amplitude of a pulse to drop from 100% to 50% of its peak value.

<math>t_{half}\;=\;t_2\;-\;t_1\,\!</math>

If terminal sialic acid residues are removed from glycoproteins, the resulting proteins are known as asialoglycoproteins.

These are transmembrane proteins where the amino terminal is cytosolic and the carboxyl terminal is exoplasmic.

These proteins have a single internal hydrophobic signal-anchor sequence that serves both as the endoplasmic reticulum signal peptide and a membrane-anchor sequence. The signal-anchor sequence is recognised by a Signal recognition particle (SRP) and is forced into the appropriate translocon to continue translation of the protein.

External links

Pulse Repetition Frequency (PRF) is the number of pulses transmitted per second by a radar. The reciprocal of this is called the Pulse Repetition Time (PRT), Pulse Repetition Interval (PRI), or Inter-Pulse Period (IPP), which is the elapsed time from the beginning of one pulse to the beginning of the next pulse. PRF is important since it determines the maximum target range (R_max) and maximum Doppler velocity (V_max) that can be accurately determined by the radar.

Range ambiguity

A radar system determines range through the time delay between pulse transmission and reception by the relation:

<math>Range = \frac{c\tau}{2}</math>

For accurate range determination a pulse must be transmitted and reflected before the next pulse is transmitted. This gives rise to the maximum range limit:

<math>Max Range = \frac{c\tau_{PRT}}{2} = \frac{c}{2PRF} \qquad \begin{cases} \tau_{PRT} = \frac{1}{PRF} \end{cases}</math>

The maximum range also defines a range ambiguity for all detected targets. Because of the periodic nature of pulsed radar systems, it is impossible for a radar system to determine the difference between targets separated by integer multiples of the maximum range using a single PRF. More sophisticated radar systems avoid this problem through the use of multiple PRFs either simultaneously on different frequencies or on a single frequency with a changing PRT.

See also

• Radar
• Pulse-Doppler radar
• Weather radar

The Neolithic founder crops (or primary domesticates) are the eight plant species that were domesticated by early Holocene (Pre-Pottery Neolithic A and Pre-Pottery Neolithic B) farming communities in the Fertile Crescent region of southwest Asia, and which formed the basis of systematic agriculture in the Middle East, North Africa, India, Persia and (later) Europe. They consist of flax, three cereals and four pulses, and are the first known domesticated plants in the world. Although domesticated rye (Secale cereale) occurs in the final Epi-Palaeolithic strata at Tell Abu Hureyra (the earliest instance of a domesticated plant species), it was an insignificant in the Neolithic Period of southwest Asia and only became common with the spread of farming into northern Europe several millennia later.

Cereals

• Emmer (Triticum dicoccum, descended from the wild T. dicoccoides)
• Einkorn (Triticum monococcum, descended from the wild T. boeoticum)
• Barley (Hordeum vulgare/sativum, descended from the wild H. spontaneum)

Pulses

• Lentil (Lens culinaris)
• Pea (Pisum sativum)
• Chickpea (Cicer arietinum)
• Bitter vetch (Vicia ervilia)

Other

• Flax (Linum usitatissimum)

Further reading

• Daniel Zohary and Maria Hopf, Domestication of Plants in the Old World, third edition. Oxford: University Press, 2000. ISBN 0-19-850356-3

In geometry, a glide reflection is a type of isometry of the Euclidean plane: the combination of a reflection in a line and a translation along that line. Reversing the order of combining gives the same result. Depending on context, we may consider a reflection a special case, where the translation vector is the zero vector.

The combination of a reflection in a line and a translation in a perpendicular direction is a reflection in a parallel line. However, a glide reflection cannot be reduced like that. Thus the effect of a reflection combined with any translation is a glide reflection, with as special case just a reflection. These are the two kinds of indirect isometries in 2D.

For example, there is an isometry consisting of the reflection on the x-axis, followed by translation of one unit parallel to it. In coordinates, it takes

(x, y) to (x + 1, −y).

It fixes a system of parallel lines.

The isometry group generated by just a glide reflection is an infinite cyclic group.

Combining two equal glide reflections gives a pure translation with a translation vector that is twice that of the glide reflection, so the even powers of the glide reflection form a translation group.

In the case of glide reflection symmetry, the symmetry group of an object contains a glide reflection, and hence the group generated by it. If that is all it contains, this type is Frieze group nr. 2.

Example pattern with this symmetry group:

+++  +    +++
+    +    +
+++  +++  +++
+    +    +
+    +++  +

Frieze group nr. 6 (glide-reflections, translations and rotations) is generated by a glide reflection and a rotation about an axis perpendicular to the line of reflection. It is isomorphic to a semi-direct product of Z and C₂.

Example pattern with this symmetry group:

 +   + +   +
+ +   +   + +

For any symmetry group containing some glide reflection symmetry, the translation vector of any glide reflection is one half of an element of the translation group. If the translation vector of a glide reflection is itself an element of the translation group, then the corresponding glide reflection symmetry reduces to a combination of reflection symmetry and translational symmetry.

In 3D the glide reflection is called a glide plane. It is a reflection in a plane combined with a translation parallel to the plane.

See also: congruence (geometry), similarity (mathematics), wallpaper group, frieze group.

External links

• Glide Reflection at cut-the-knot

Alloantigen can be defined as an antigen that is a part of an animal’s self-recognition system. e.g., Major histocompatibility complex molecules. When injected into another animal, they trigger an immune response aimed at eliminating them. Therefore, it can thought of as an antigen that is present in some members of the same species, but is not common to all members of that species. If an alloantigen is presented to a member of the same species that does not have the alloantigen, it will be recognized as foreign. They are the products of polymorphic genes.Abbas AK and Lichtman AH. Basic Immunology: Functions and Disorders of the Immune System. Second Edition, Updated Edition 2006-2007. Elsevier Saunders Publishing.

See also

• Isoantigen

References

External links

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In physics, a coincidence circuit is an electronic device with one output and two (or more) inputs. The output is activated only when signals are received at the same time at both inputs. Coincidence circuits are widely used in particle physics experiments and in other areas of science and technology.

Walther Bothe shared the Nobel Prize for Physics in 1954 “for his discovery of the method of coincidence and the discoveries subsequently made by it”. Bruno Rossi invented the electronic coincidence circuit for implementing the coincidence method.

In his Nobel Prize lecture, Bothe described how he had implemented the coincidence method in an experiment on Compton scattering in 1924. The experiment was aimed to check whether Compton scattering produces a recoil electron simultaneously with the scattered gamma ray. Bothe used two point discharge counters connected to separate fibre electrometers and recorded the fibre deflections on a moving photographic film. On the film record he could discern coincident discharges with a time resolution of approximately 1 millisecond.

In 1929, Walther Bothe and Werner Kohlhörster published the description of a coincidence experiment with tubular discharge counters invented in 1928 by Hans Geiger and Wilhelm Müller. The Bothe-Kohlhörster experiment demonstrated the presence of penetrating charged particles in cosmic rays. They used the same mechanical-photographic method for recording simultaneous discharges which, in this experiment, signalled the passage of a charged cosmic ray particle through both counters and through the thick wall of lead and iron with which they had surrounded the counters. Their paper, entitled “Das Wesen der Höhenstrahlung”, was published in the Zeitschrift für Physik v.56, p.751 (1929).

Bruno Rossi, at the age of 24, was in his first job as assistant in the Physics Institute of the University of Florence when he read the Bothe-Kohlhörster paper. It inspired him to begin his own research on cosmic rays. He fabricated Geiger tubes according to the published recipe, and he invented the first practical electronic coincident circuit. It employed several triode vacuum tubes, and was capable of registering coincident pulses from any number of counters with a tenfold improvement in time resolution over the mechanical method of Bothe. Rossi described his invention in a paper entitled “Method of Registering Multiple Simultaneous Impulses of Several Geiger Counters”, published in Nature v.125, p.636 (1930). The Rossi coincidence circuit was rapidly adopted by experimenters around the world. It was the first practical AND circuit, precursor of the AND logic circuits of electronic computers.

To detect the voltage pulse produced by the coincidence circuit when a coincidence event occurred, Rossi first used earphones and counted the ‘clicks’, and soon an electro-mechanical register to count the coincidence pulses automatically. Rossi used a triple-coincidence version of his circuit with various configurations of Geiger counters in a series of experiments during the period from 1930 to 1943 that laid an essential part of the foundations of cosmic-ray and particle physics.

About the same time and independently of Rossi, Bothe devised a less practical electronic coincidence device. It employed a single pentode vacuum tube and could register only twofold coincidences.

The main idea of ‘coincidence detection’ in signal processing is that if a detector detects a signal pulse in the midst of random noise pulses inherent in the detector, there is a certain probability, p, that the detected pulse is actually a noise pulse. But if two detectors detect the signal pulse simultaneously, the probability that it is a noise pulse in the detectors is p². Suppose p=0.1. Then p²=0.01. Thus the chance of a false detection is reduced by the use of coincidence detection.

References

Year’s Best Fantasy and Horror is a respected reprint anthology published annually by St. Martin’s Press. In addition to the short stories, supplemented by a list of honorable mentions, each edition includes a number of retrospective essays by the editors and others.

For most of its run, the series has been edited by Terri Windling and Ellen Datlow, with Windling primarily responsible for the “fantasy” portion of the content and Datlow for the “horror” portion. From the 16th edition (covering works first published in 2003), Windling’s role has been taken by the team of Kelly Link and Gavin Grant.

Pulse Demon is an album by Japanese noise music musician Masami Akita, under the name Merzbow. The original pressing was released in a double-fold Digipak, while it was later re-released in a normal jewel case.

Track listing

1. “Woodpecker No. 1″ – 6:42
2. “Woodpecker No. 2″ – 3:37
3. “Spiral Blast” – 4:30
4. “My Station Rock” – 4:54
5. “Ultra Marine Blues” – 11:29
6. “Tokyo Times Ten” – 11:09
7. “Worms Plastic Earthbound” – 24:53
8. “Yellow Hyper Balls” – 6:03

In signal processing and telecommunication, the term pulse duration has the following meanings:

1. In a pulse waveform, the interval between (a) the time, during the first transition, that the pulse amplitude reaches a specified fraction (level) of its final amplitude, and (b) the time the pulse amplitude drops, on the last transition, to the same level.

   Note: The interval between the 50% points of the final amplitude is usually used to determine or define pulse duration, and this is understood to be the case unless otherwise specified. Other fractions of the final amplitude, e.g., 90% or 1/e, may also be used, as may the root mean square (rms) value of the pulse amplitude. Deprecated synonyms: pulse length, pulse width.

2. In radar, measurement of pulse transmission time in microseconds, that is, the time the radar’s transmitter is energized during each cycle.

Source: From Federal Standard 1037C and from MIL-STD-188 and from the Department of Defense Dictionary of Military and Associated Terms

A bed of nails tester is a traditional electronic test fixture comprised of numerous pins inserted into holes in an acrylic plate which are aligned to make contact with test points on a printed circuit board and are also connected to a measuring unit by wires.

Typically, four to six weeks are needed for the manufacture and programming of such a fixture. Fixture can either be vacuum or press-down. Vacuum fixtures give better signal reading versus the press-down type. The bed of nails or fixture as generally termed is used together with a in-circuit tester such as i3070, 3070 from Agilent (USA), Teradyne Spectrum Series and continuation of the old Genrad Teststation series under the Teradyne flag (USA), IFR 4200 series, was Marconi Test prior to acquisition by IFR (USA), TRI (Tiawan), Digitaltest(Germany), Okano (Japan), Checksum (USA).

The Checksum system is an entry level machine selling for approx. USD$10K and finding approximately 95-98% of manufacturing defects. The Teradyne system is a system designed for high end manufacture and military use, and sells for approx. USD$200K plus.

“During board layout, one of the primary concerns is that accurate tooling holes and appropriate test pad size and location are all critical to increasing the probability that the spring-loaded probes in a bed-of-nails test fixture will reliably make contact and transfer signals to and from the board under test.” Blackwell, The Electronic Packaging Handbook

This technique of testing PCB’s is being slowly superseded by Boundary Scan techniques (Silicon Test Nails) and Automatic Optical Inspection, due to shrinking product sizes and lack of space on PCB’s for test pads.

Example of In-Circuit Test Product

Continuous-wave radar system is a radar system where a known stable frequency continuous wave radio energy is transmitted and then received from any reflecting objects. The return frequencies are shifted away from the transmitted frequency based on the Doppler effect if they are moving.

The main advantage of the CW radars is that they are not pulsed and simple to manufacture. They have no minimum or maximum range (although the broadcast power level imposes a practical limit on range) and maximize power on a target because they are always broadcasting. However they also have the disadvantage of only detecting moving targets, as stationary targets (along the line of sight) will not cause a Doppler shift and the reflected signals will be filtered out. CW radar systems are used at both ends of the range spectrum; e.g., as radio-altimeters at the close-range end (where the range may be a few feet), and early warning radars at long range.

CW radars also have a disadvantage because they cannot measure range. Range is normally measured by timing the delay between a pulse being sent and received, but as CW radars are always broadcasting, there is no delay to measure. Ranging can be implemented, however, through a technique known as “chirping”, or frequency modulated continuous-wave radar. In this system the signal is not a continuous fixed frequency, but varies up and down over a fixed period of time. By comparing the frequency of the received signal to the one currently being sent, the difference in frequency can be accurately measured, and from that the time-of-flight can be calculated.

The military uses continuous-wave radar to guide semi-active radar homing (SARH) air-to-air missiles, such as the U.S. AIM-7 Sparrow. The launch aircraft illuminates the target with a CW radar signal, and the missile homes in on the reflected radar waves. Since the missile is moving at high velocities relative to the aircraft, there is almost always a strong return. Most modern air combat radars, even pulse Doppler sets, have a CW function for missile guidance purposes.

See also

• Doppler radar
• Fm-cw radar
• Pulse-doppler radar

A golden umbrella is a clause in an entrepreneur’s contract with their company, typically the CEO or COO, that guarantees a certain payout for the risk they bear in starting the company.

The down-side of a golden umbrella is that angel investors typically do not know the terms of a golden umbrella, thus a CEO may start a company, grow the company, seek first-round and second-round venture capital, and then exit the company with a large pay-out just before the company’s market growth takes a downturn due to poor business planning.

See also

• Golden handshake
• Golden parachute

Connection is a popular single released by the Britpop group Elastica. It was originally released in 1994 as a single and the album version was not released until 1995 on the self-titled debut. It is best known as the theme tune to the UK television programme Trigger Happy TV.

Chart positions

Hoeffding’s inequality, named after Wassily Hoeffding, is a result in probability theory that gives an upper bound on the probability for the sum of random variables to deviate from its expected value.

Let

<math>X_1, \dots, X_n \!</math>

be independent random variables. Assume that the <math>X_i</math> are almost surely bounded; that is, assume for <math>1\leq i\leq n</math> that

<math>\Pr(X_i \in [a_i, b_i]) = 1. \!</math>

Then, for the sum of these variables

<math>S = X_1 + \cdots + X_n \!</math>

we have the inequality (Hoeffding 1963, Theorem 2):

<math>\Pr(S - \mathrm{E}[S] \geq nt) \leq \exp \left( - \frac{2\,n^2\,t^2}{\sum_{i=1}^n (b_i - a_i)^2} \right),\!</math>

which is valid for positive values of t (where <math>\mathrm{E}[S]</math> is the expected value of <math>S</math>).

This inequality is a special case of the more general Bernstein inequality in probability theory, proved by Sergei Bernstein in 1923. It is also a special case of McDiarmid’s inequality.

See also

• Chebyshev’s inequality, Markov’s inequality and Chernoff bounds.

• Azuma’s inequality

Primary sources

• Wassily Hoeffding, Probability inequalities for sums of bounded random variables, Journal of the American Statistical Association 58 (301): 13–30, March 1963. (JSTOR)

All Jets Are Gonna Fall Today is the debut full-length album by Julian Koster’s Chocolate USA. Released in 1992, it was their first release for Bar/None Records.

Track listing

1. Test (Koster) :40
2. All Jets Are Gonna Fall Today (Koster) – 3:14
3. Doogie Love Theme/Wysotsky’s Tea (Koster) – 2:25
4. My Little Two Eyes (Koster) – 3:04
5. 100 Feet Tall (Koster) – 2:36
6. The Feelies Show (Koster) – 3:02
7. Skyphilis/Air Raid (Koster) – 3:46
8. The Shower Song (Koster) – 3:57
9. Wash My Face (Koster) – 4:32
10. Two Dogs (Koster) – 1:58
11. Vocal Exercise No. 1 (Koster) :32
12. The Crashing Song (Koster) – 2:33
13. Luniks Furniture (Koster) – 2:39
14. Kriss Ford (Koster) – 2:43
15. Kathy (Koster) – 1:38
16. Nervous Aged Catalunian (Koster) – 3:07
17. Loud (Koster) – 4:22
18. Smile (Koster) – 3:27
19. She’s an Aeroplane (Koster) – 4:21

The clock hypothesis is an assumption in special relativity. It states that the speed of clocks doesn’t depend on their acceleration but only on their instantanous velocity. This is equivalent to stating, that a clock moving along a path <math>P</math> measures the proper time, defined by:

<math>d \tau = \int_P \sqrt {dt^2 - dx^2/c^2 - dy^2/c^2 - dz^2/c^2}</math>.

The clock hypothesis wasn’t included in Einstein’s original 1905 formulation of special relativity and therefore, the theory was unable to make predictions for accelerated systems. Since then, it has become a standard assumption and is usually included in the axioms of special relativity, especially in the light of experimental verification up to very high accelerations in particle accelerators.

Hermann Weyl was a notable critic of the clock hypothesis.

References

• S.R. Mainwaring, G.E. Stedman, Accelerated Clock Principles in Special Relativity. Physical Review A47 (1993) 3611–3619.
• R. Anderson, I. Vetharaniam, G.E. Stedman, Conventionality of Synchronization, Gauge Dependence and Test Theories of Relativity., Physics Reports 295 (1998) 94–180.
• A.M. Eisele, On the Behavior of an Accelerated Clock, Helvetica Physica Acta 60 (1987) 1024–1037.
• P. Mittelstaedt, H. Heintzmann, Laws of Physics in Accelerated Reference Frames (German), in Springer Tracts in Modern Physics (G. Höhler, ed.) 47 (1968) 185-225.

External links

• gr-qc/9908048 Harvey R. Brown, Oliver Pooley, The origin of the spacetime metric: Bell’s `Lorentzian pedagogy’ and its significance in general relativity
• “Does a clock’s acceleration affect its timing rate?”, from the USENET Physics FAQ

• Joseph Haydn
  
  • 52 Sonatas

• Carl Philipp Emanuel Bach
  • Sonatas
  • La Caroline

• Ludwig van Beethoven
  • 32 Sonatas
  • Diabelli Variations

• Frédéric Chopin
  • see: List of compositions by Frédéric Chopin

• Wolfgang Amadeus Mozart
  • 19 Sonatas
  • Fantasias for Piano

• Bach

See also Lists of solo piano pieces.

Tranduction is the transformation of one form of energy to another. In psychology, transduction refers to the nervous system.

In the nervous system, transduction occurs when environmental energy is transformed into electrical or neural energy. Receptor cells produce an electrical change in response to a physical stimulus.

According to Jean Piaget’s theories on cognitive development, transductive reasoning is the primary form of reasoning used during the preoperational stage of development. This stage occurs approximately from the ages of 2-7. Transductive reasoning employs the following reasoning: “If A causes B today, then A always causes B.”

The term blind-baking (sometimes called “pre-baking”) refers to the process of baking a pie crust or other pastry without the filling.

Generally, the pie crust is lined with tin foil or parchment paper, then filled with dried peas, lentils, beans or other pulses, so that it will keep its shape when baking. Metal or ceramic pie weights are also used. After the pie crust is done, the pulses are replaced with the proper filling. Blind-baking is necessary if the pie filling can not be baked as long as the crust requires, or if the filling of the pie would make the crust too soggy if added immediately.

Blind-baking also helps to form a nice pastry case for the filling as it has already been partially formed from blind-baking.

External links

• Blind baking video

The superposition theorem for electric circuits states that the total current in any branch of a bilateral linear circuit equals the algebraic sum of the currents produced by each source acting separately throughout the circuit.

To ascertain the contribution of each individual source, all of the other sources first must be “killed” (set to zero) by:

1. replacing all other voltage sources with a short circuit (thereby eliminating difference of potential. i.e. V=0)
2. replacing all other current sources with an open circuit (thereby eliminating flow of current. i.e. I=0)

This procedure is followed for each source in turn, then the resultant currents are added to determine the true operation of the circuit. The resultant circuit operation is the superposition of the various voltage and current sources.

External links

• All About Circuits - gives its own explanation of the superposition theorem.

References

• Electronic Devices and Circuit Theory 9th ed. by Boylestad and Nashelsky
  

Operation Noah may refer to:

• Operation Noah (World War II), a 1944 reconnaissance operation by the Belgian Special Air Service
• Operation Noah (Kariba), a 1959 operation in Zambia and Zimbabwe to move animals from a flooding dam site
• Operation Noah (organization), an organization of United Kingdom churches concerned with climate change and the environment
• Operation Noah’s Ark, an operation relocating animals from Namibia and Botswana to Angola

Albertville (2006 population 110) is a village in central Saskatchewan, Canada, approximately 25 km northeast of Prince Albert.

Dual naming is a policy for the naming of geographical landmarks, in which an official name is adopted that combines two previous names. Usually, the context is a conflict over which of the two previous names is most appropriate.

In several countries, dual naming is used where a native people and a colonial settler community have previously used two names.

In Australia, a dual naming policy is used to name landmarks that are of significance to the Indigenous Australians, but for which the most common name is European. For example, the landmark with Indigenous name Uluru and European name Ayers Rock is now officially Uluru / Ayers Rock.

Similarly, in New Zealand, many places have dual Maori and English names, such as Aoraki/Mount Cook.

Billennium is a neologism which is a combination either of “billion” and “millennium”, that is a period of a billion years, or a combination of “bi-” and “millennium”, that is a second millennium, such as that which ended in the year 2000.

The word “billennium” is used by such writers as Madeleine L’Engle (A Wind in the Door), Stanisław Lem (Imaginary Magnitude) and J. G. Ballard in a collection of short stories under the same name, apparently in reference to a billion years.

See also:

• Unix billennium
• Beretta 92 Billennium

The word “billennium” should not be confused with “biennium”, a period of two years.

SLK may stand for:

• Mercedes-Benz SLK, a sports car
• Spear, Leeds & Kellogg, a subsidiary of the Goldman Sachs Group
• SLK (parser generator), an LL(k) parser generator for the programming languages C, C++, Java and C#
• the IATA code for Adirondack Regional Airport located in Adirondack State Park
• SLK (Street Light Knights), a ska band from southwestern Michigan, with recorded albums, early to mid-eighties
• .slk Filename extension for the SYmbolic LinK (SYLK) database/spreadsheet format
• Superior limbic keratoconjunctivitis, an inflammatory disorder of the cornea
• Saaremaa Laevakompanii, a shipping company in Estonia

A Pulse Forming Network (PFN) accumulates electrical energy over a comparatively long time, then releases the stored energy in the form of a relatively square pulse of comparatively short duration for various pulsed power applications. In practice, a PFN is charged by means of a high voltage power source, then rapidly discharged into a load via a high voltage switch, such as a spark gap or hydrogen thyratron. The load may be a high power microwave oscillator such as a klystron or magnetron, a flash lamp, or even an electromagnet. Depending upon the application, the output pulse repetition rate may range from a fraction of a Hertz to over 10kHz.

Implementation

A PFN consists of a series of high voltage energy storage capacitors and inductors. These components are interconnected (as a “ladder network“) that behaves similar to a length of transmission line. For this reason, a PFN is sometimes called an “artificial, or synthetic, transmission line“. Electrical energy is initially stored within the charged capacitors of the PFN.

Sometimes an actual length of transmission line is used as the pulse forming network. This can give substantially flat topped pulses at the inconvenience of using of a large length of cable.

A Blumlein transmission line is a particular confuguration of transmission lines used to create high-voltage pulses with short rise and fall times. Its principle is closely related to a pulse-forming transmission line discharge, although a Blumlein’s output voltage is the same as the charging voltage whereas the Pulse-forming transmission line outputs half the charging voltage.

Uses of PFNs

Upon command, a high voltage switch then transfers the energy stored within the PFN into the load. When the switch “fires“, the network of capacitors and inductors within the PFN creates an approximately square output pulse of short duration and high power. This high power pulse becomes a brief source of high power to the load.

Sometimes a specially designed pulse transformer is connected between the PFN and load. This technique improves the impedance match between the PFN and the load so as to improve power transfer efficiency. A pulse transformer is typically required when driving higher impedance devices such as klystrons or magnetrons from a PFN. Because the PFN is charged over a relatively long time and then discharged over a very short time, the output pulse may have a peak power of megawatts or even terawatts.

The combination of high voltage source, PFN, HV switch, and pulse transformer (when required) is sometimes called a “power modulator” or “pulser“.

See also

• Pulse-code modulation
• Pulse-position modulation
• Pulse-width modulation
• Pulse-density modulation
• Crossatron
• radar modulators
• missile operations
• lasers
• pulsed power
• particle accelerators

External links and references

• “Pulse Forming Networks“. Plastic Capacitors, Inc.
• Eric Heine, “Conversion“. NIKHEF Electronic Department, Amsterdam, The Netherlands.
• “Pulse power system design“. United Defense, Arlington, VA.
• Riepe, Kenneth B., “High-voltage microsecond pulse-forming network“. Review of Scientific Instruments Vol 48(8) pp. 1028-1030. August 1977. (Abstract)
• Glasoe, G. Norris, Lebacqz, Jean V., “Pulse Generators“, McGraw-Hill, MIT Radiation Laboratory Series, Volume 5, 1948.

Scientific progress is the idea that science increases its problem solving ability through the application of some scientific method.

Discontinuous Model of Scientific Progress

Several Philosophers of Science have supported arguments that the progress of science is discontinuous. In that case, progress is not a continuous accumulation, but rather a revolutionary process where brand new ideas are adopted and old ideas become abandoned. Thomas Kuhn was a major proponent of this model of scientific progress, as explained in his book The Structure of Scientific Revolutions.

This is especially supported by studying the incommensurability of theories. For example, consider Newtonian mechanics and relativistic mechanics. From a strict vantagepoint, in newtonian mechanics mass and energy are always conserved, where in relativistc mechanics energy and mass are always interchangeable. (Note the difference between the strict vantagepoint, and the layperson’s vantagepoint that Newton’s theory is applicable at low energies and low velocities relative to the velocity of light.) Because the theories are completely incompatible, scientists using one paradigm will not be able to discuss meaningfully with scientists from the other paradigm.

A discontinuous model of scientific progress may disagree with a realist’s construction in the philosophy of science. This is because the intrinsic nature of the objects referred to may change wildly.

History of Science as a Model of Scientific Progress

Another model of Scientific Progress, as put forward by Richard Boyd, and others, is History of Science as a model of scientific progress. In short, methods in science are produced which are used to produce scientific theories, which then are used to produce more methods, which are then used to produce more theories and so on.

Note that this does not conflict with a continuous or discontinuous model of scientific progress. This model supports realism in that scientists are always working within the same universe; their theories must be referring to real objects, because they create theories that refer to actual objects that are used later in methods to produce new theories.

A good example supporting realism is the case of the electron. It is hard to prove the existence of an electron because it is so small. However, any microscopist will tell you that he knows an electron exists, because he uses it in his electron microscope.

Origins of the concept

Early technological and religious traditions did not concern themselves with gaining knowledge in any systematic way, and thus the concept of scientific progress would have been largely alien to them. Societies deeply invested in tradition were primarily occupied with the verbatim passing of thoughts and practises to the next generation, and did not engage in the scientific method.

Even if some esoteric traditions may have involved themselves with a rudimentary experimental method as the nucleus of their initiation, they did not overtly separate exploration from instruction.

Some classical Greeks like Hippocrates did systematically gather evidence, but as a concept incremental increase of knowledge is first formulated in connection with the art of warfare.

Quotes on Scientific Progress

Dr. Terry Halwes wrote:

“What is required for scientific progress is mainly ordinary curiosity, ordinary awareness, ordinary learning, ordinary reasoning, and fairly ordinary communication. Of course scientists work hard to develop and use precise technical terms for many of the things they talk about, but so do lawyers and golfers and cooks.” [1]

Sir Karl Popper wrote in The Logic of Scientific Discovery:

The wrong view of science betrays itself in the craving to be right; for it is not his possession of knowledge, of irrefutable truth, that makes the man of science, but his persistent and recklessly critical quest for truth. [2]

The Science Hobbyist says:

Lots of important science comes NOT from proposing hypotheses or even from performing experiments, but instead comes from unguided observation and curiosity-driven exploration: from sniffing about while learning to see what nobody else can see. Scientific discovery comes from something resembling “informed messing around,” or unguided play. [3]

External links

• Stanford Encyclopedia of Philosophy entry

Pulse Demon is an album by Japanese noise music musician Masami Akita, under the name Merzbow. The original pressing was released in a double-fold Digipak, while it was later re-released in a normal jewel case.

Track listing

1. “Woodpecker No. 1″ – 6:42
2. “Woodpecker No. 2″ – 3:37
3. “Spiral Blast” – 4:30
4. “My Station Rock” – 4:54
5. “Ultra Marine Blues” – 11:29
6. “Tokyo Times Ten” – 11:09
7. “Worms Plastic Earthbound” – 24:53
8. “Yellow Hyper Balls” – 6:03

1. REDIRECTContinuously variable transmission

The Continuously Variable Transmission (CVT) is a transmission in which the ratio of the rotational speeds of two shafts, as the input shaft and output shaft of a vehicle or other machine, can be varied continuously within a given range, providing an infinite number of possible ratios.

The Continuously Variable Transmission (CVT) should not be confused with the Infinitely Variable Transmission (IVT). The IVT is a specific type of CVT that has an infinite range of input/output ratios in addition to its infinite number of possible ratios; this qualification for the IVT implies that its range of ratios includes a zero output/input ratio that can be continuously approached from a defined ‘higher’ ratio. A zero output implies an infinite input, which can be continuously approached from a given finite input value with an IVT. [Note: remember that so-called ‘low’ gears are a reference to low ratios of output/input which have high input/output ratios that are taken to the extreme with IVT’s, resulting in a ‘neutral’, or non-driving ‘low’ gear limit.] Generally, the usage of the term ‘CVT’ is not used for Infinitely Variable Transmissions because most CVT’s are not IVT’s.

The Continuously Variable Transmission (CVT) should not be confused with the Power Split Transmission (PST), as used in the Toyota Prius and other hybrid vehicles that use two or more inputs with one output. PST’s are not CVT’s, despite some similarities in their function.

CVT’s are not intrinsically automatic, nor do they intrinsically include zero or reverse output. Such features may be adapted to CVT’s in certain specific applications.

Other mechanical transmissions only allow a few different discrete gear ratios to be selected, but the continuously variable transmission essentially has an infinite number of ratios available within a finite range, so it enables the relationship between the speed of a vehicle engine and the driven speed of the wheels to be selected within a continuous range. This can provide better fuel economy than other transmissions by enabling the engine to run at its most efficient speeds within a narrow range.

Pulse-density modulation, or PDM, is a form of modulation used to represent an analog signal in the digital domain. In a PDM signal, specific amplitude values are not encoded into pulses as they would be in PCM. Instead it is the relative density of the pulses that corresponds to the analog signals amplitude. Pulse-width modulation (PWM) is the special case of PDM where all the pulses corresponding to one sample are contiguous in the digital signal.

Basics

In a pulse-density modulation bitstream a 1 corresponds to a pulse of positive polarity (+A) and a 0 corresponds to a pulse of negative polarity (-A). Mathematically, this can be represented as:

<math> x[n] = -A (-1)^{a[n]} \ </math>

where x[n] is the bipolar bitstream (either -A or +A) and a[n] is the corresponding binary bitstream (either 0 or 1).

A run consisting of all 1’s would correspond to the maximum (positive) amplitude value, all 0’s would correspond to the minimum (negative) amplitude value, and alternating 1’s and 0’s would correspond to a zero amplitude value. The continuous amplitude waveform is recovered by low-pass filtering the bipolar PDM bitstream.

Analog-to-digital conversion

A PDM bitstream is encoded from an analog signal through the process of delta-sigma modulation. This process uses a one bit quantizer that produces either a 1 or 0 depending on the amplitude of the analog signal. A 1 or 0 corresponds to a signal that is all the way up or all the way down, respectively. Because in the real world analog signals are rarely all the way in one direction there is a quantization error, the difference between the 1 or 0 and the actual amplitude it represents. This error is fed back negatively in the ΔΣ process loop. In this way every error successively influences every other quantization measurement and its error. This has the effect of averaging out the quantization error.

Digital-to-analog conversion

The process of decoding a PDM signal into an analog one is amazingly simple. One only has to pass that signal through an analog low-pass filter. This works because the function of a low-pass filter is essentially to average the signal. The density of pulses is measured by the average amplitude of those pulses over time, thus a low pass filter is the only step required in the decoding process.

Examples/algorithm

A single period of the trigonometric sine function, sampled 100 times and represented as a PDM bitstream, is:

0101011011110111111111111111111111011111101101101010100100100000010000000000000000000001000010010101

Two periods of a higher frequency sine wave would appear as:
0101101111111111111101101010010000000000000100010011011101111111111111011010100100000000000000100101
or

In pulse-density modulation, a high density of 1’s occurs at the peaks of the sine wave, while a low density of 1’s occurs at the troughs of the sine wave.

The following algorithm can be used to replicate the above examples.

 //Produce s samples of p periods of a sine wave
 function sample(int s, int p)
   s := s - 1
   var real ω := p × π × 2 ÷ s
   var real[0..s] pcm
   for i from 0 to s
       pcm[i] := sin(ω × i)
   return pcm

 //Encode samples into pulse-density modulation
 //using naive noise shaping
 function encode(real[0..s] pcm)
   var int[0..s] pdm
   var real r := 1
   for i from 0 to s
       r := pcm[i] - r
       if r > 0
           pdm[i] := 1
           r := 1 - r
       else
           pdm[i] := 0
           r := -1 - r
   return pdm

Applications

PDM is the encoding used in Sony’s Super Audio CD (SACD) format, under the name Direct Stream Digital.

Alcoholic Beverage Control may refer to:

• Alcoholic beverage control states
• The California Department of Alcoholic Beverage Control

The vagus nerve plays a role in (amongst other things) controlling the pulse. The vagus reflex is a reaction which can reduce the pulse rate during tachycardia (racing pulse). The following stimuli may produce the vagus reflex:

• tensing the lower abdomen (similar to straining at stool)
• gentle pressure on the closed eyes
• a gulp of ice-cold water
• splashing ice-cold water on the face
• immersing the arms in ice-cold water
• finger stuck down the throat
• the insertion of an IV needle
• cough or sneeze (involuntary or autonomic works best)
• holding breath (after exhaling) - see Valsalva manoeuvre

Polymeric membranes are membranes that take the form of polymeric interphases, which can selectively transfer certain chemical species over others. There are several mechanisms that could be deployed in their functioning. Knudsen diffusion and solution diffusion are prominent mechanisms. Polymeric membranes are of particular importance in gas separation applications. Key industrial applications include: oxygen-nitrogen separation, removal of organics and natural gas enrichment.
{{Category:Chemistry]]

Bishop Daniel F. Feehan (1855-1934) was the second Bishop to serve the Diocese of Fall River. The son of William and Joanna (Foley) Feehan he was born in Athol, Massachusetts on September 24, 1855. The family moved to Milbury, Massachusetts, when Daniel was only three years old. He graduated from St. Mary’s College in Montreal, Canada. He studied at St. Joseph Seminary in Troy, New York and was ordained a priest on December 29, 1879. He served in the Diocese of Springfield in Massachusetts. On July 2, 1907 he was appointed Bishop of Fall River. Ordained a bishop on September 19, 1907 by Bishop Thomas Daniel Beaven, he served the people of the diocese until incapacitation due to senility. Bishop Feehan died on July 19, 1934.

Bishop Feehan High School, a parochial school in Attleboro, Massachusetts, was named for him when it opened in 1961.

The 4Pi-STED-microscope is the result of combining the two unrelated concepts of STED- and 4Pi-microscopy. Here, the fluorescent sample is placed in the common focus of two opposing lenses, but excitation and detection are performed through a single lens (4Pi mode A). The green excitation pulse is immediately followed by a red STED-pulse, which enters the focal region through both lenses inducing stimulated emission of the excited fluorescent molecules to the ground state. To permit fluorescence emission from the center but suppress it from neighbouring regions it is useful to phaseshift the STED beam to have a minimum at the center.

External links

Technical details

Pulse Global is a family of radio stations, exclusively playing new, unsigned, and emerging artists over the internet. The following franchises are currently operating:-

• Pulse Rated - operating from the UK and covering Europe and the rest of the world, Pulse Rated broadcasts over the internet at http://uk.pulserated.com.
• Pulse Rated (Americas) - operates from Los Angeles, this station covers the North America region, broadcasting over the internet at http://usa.pulserated.com.

Company profile:

Over the last 2 years, Pulse has firmly established itself as the world’s leading internet & satellite radio broadcaster playing only the very best music from new, unsigned, and emerging artists from around the world.

Pulse exists to provide a unique, and importantly free, resource for the promotion and support of talented new artists by making sure they are heard by the largest possible audience.

The two stations currently feature and promote over 2,300 acts from a total of 39 countries, all of whom have been through the stringent Pulse selection and legal process in order to grant Pulse specific non-exclusive rights.

Corporate operations are currently managed from the UK division, who franchise the brand name and services out to various territories.

Takayoshi Nakazato (中里 尚義 Nakazato Takayoshi) is a video game director for Square Enix. He has been credited on the following titles during his employment with the company:

• Dirge of Cerberus: Final Fantasy VII — (2006; as Director)
• Final Fantasy X-2 — (2003; as Field Planning Director)
• Final Fantasy X — (2001; as Map Director)

External links

Russ Nicholson is a British illustrator, best known for his work on the Fighting Fantasy gamebook series, in particular, The Warlock of Firetop Mountain, and numerous Games Workshop products, including Warhammer Fantasy Battle, Warhammer Fantasy Roleplay, Warhammer 40,000 and to their magazine White Dwarf.
He imaginatively illustrated the published “episodes” of the Fabled Lands series, which was originally planned as an interactive ‘gamebook’ to be published in 12 parts, created by Dave Morris and Jamie Thomson.

He also illustrated many creatures in the original Fiend Folio, a UK contribution to the first edition of the Advanced Dungeons and Dragons game. Noted mostly for his own distinct black and white style, he has also done several colour pieces as well.

The Black Sturgeon River is a river in the Thunder Bay District of northwestern Ontario located west of Lake Nipigon. It flows from Black Sturgeon Lake to empty into Black Bay on Lake Superior. The river valley follows a major fault line in the area which runs north-south.

In graph theory, the Lovász conjecture (1970) is a classical problem on Hamiltonian paths in graphs. It says:

Every finite connected vertex-transitive graph contains a Hamiltonian path.

The original article of Lovász stated the result in the opposite, but
this version became standard. In 1996 Babai
published a conjecture sharply contradicting this conjecture,
but both conjectures remain widely open.
It is not even known if a single counterexample would necessarily lead to a series of counterexamples.

Historical remarks

The problem of finding Hamiltonian paths in highly symmetric graphs is quite old.
As Knuth describes it in the forthcoming 4-th volume of The Art of Computer Programming, the problem
originated in British campanology (bell-ringing). Such Hamiltonian paths and cycles are also closely connected to Gray codes. In each case the constructions are explicit.

Cayley graphs

Another version of Lovász conjecture states that

Every finite connected Cayley graph contains a Hamiltonian cycle.

While this version is open as well, there exist an example
of vertex-transitive graph with no Hamiltonian cycles
(but with Hamiltonian paths). This example is the Petersen graph.

The advantage of the Cayley graph formulation is that such graphs
correspond to a finite group <math>G</math> and a
generating set <math>S</math>. Thus one can ask
for which <math>G</math> and <math>S</math> the conjecture holds
rather than attack it in full generality.

Special cases

The Lovász conjecture is straightforward for abelian groups. It was proved in 1986 to hold for p-groups by D. Witte. It is open even for dihedral groups, although for special sets of generators some progress has been made.

When group <math>G = S_n</math> is a symmetric group, the
are many attractive generating sets. For example,
Lovász conjecture holds in the following cases of generating sets:

• <math>a = (1,2,\dots,n), b = (1,2)</math> (long cycle and a transposition).
• <math>s_1 = (1,2), s_2 = (2,3), \dots, s_{n-1} = (n-1,n)</math> (Coxeter generators).
• any set of transpositions corresponding to a labelled tree on <math>\{1,2,..,n\}</math>.
• <math>a =(1,2), b = (1,2)(3,4)\cdots, c = (2,3)(4,5)\cdots</math>

General groups

For general finite groups, only a few results are known:

• <math>S=\{a,b\}, (ab)^2=1</math> (R.A. Rankin generators)
• <math>S=\{a,b,c\}, a^2= b^2=c^2=[a,b]=1</math> (Rapaport-Strasser generators)
• <math>S=\{a,b,c\}, a^2=1, c = a^{-1}ba</math> (Pak-Radoičić generators)
• <math>S=\{a,b\}, a^2 = b^s =(ab)^3 = 1, </math> where <math>|G|,s = 2~mod ~4</math> (here we have (2,s,3)-presentation, Glover-Marušič theorem)

Finally, it is known that for every finite group <math>G</math> there exists
a generating set of size at most <math>\log_2 |G|</math> such that
the corresponding Cayley graph is Hamiltonian (Pak-Radoičić). This result is based on classification of finite simple groups.

The Lovász conjecture was also established for random generating sets of size <math>\Omega(\log^5 |G|)</math> (Krivelevich-Sudakov [1]).

Directed graph version

For directed Cayley graphs (digraphs) the Lovász conjecture is false. Various counterexamples were obtained by R.A. Rankin. Still, many of the above results hold in this restrictive setting.

References

• L. Babai, Automorphism groups, isomorphism, reconstruction, in Handbook of Combinatorics, Vol. 2, Elsevier, 1996, 1447-1540.
• D. E. Knuth, The Art of Computer Programming, Vol. 4, draft of section 7.2.1.2.
• I. Pak, R. Radoičić, Hamiltonian paths in Cayley graphs, 2002.

Document! X is a documentation generator which automates technical documentation production for VB6/VBA source code, C#/VB.NET/[[C++/CLI]] or other .NET language assemblies, databases, COM components, type libraries and XSD schemas. Document! X consists of an authoring and documentation build environment (including HTML based Visual Authoring tools) as well as Visual Comment Editor Add-Ins for Visual Basic, VBA and Visual Studio .NET (2002, 2003 and 2005).

See also

• List of documentation generators
• Comparison of documentation generators

External links

• webpage

Fantasy

football can refer to:

• Fantasy football (American)
• Fantasy football (soccer)
• Fantasy football (board games)
• Fantasy Football League
• Fantasy Football (Australian Rules)

Jim Sonzero is a music video and film director. He co-directed Mariah Carey’s “Can’t Let Go”. His feature length directorial debut was Pulse, a horror movie starring Kristen Bell.

Urobilin is a yellow linear tetrapyrrole, resulting from the breakdown of haem, a cyclic tetrapyrrole. Urobilin is generated in intestines from bilirubin. It is absorbed into blood stream and is supposed to be degraded in liver. When there is liver failure, urobilin starts being excreted by kidneys. It then can be found in urine (which is abnormal sign, confirming jaundice), hence its name.

External links

KCMO may refer to:

• informally, Kansas City, Missouri
  • an AM radio station there: KCMO (AM) AM 710
  • an FM radio station there: KCMO-FM 94.9
  • a former TV station there: KCMO-TV, now KCTV (TV)

A zero crossing threshold detector is an electronic circuit that consists of an operational amplifier with an input voltage at its positive input (see circuit diagram). Often used in conjunction with other circuit elements, it usually functions as a simple voltage switch.

When the input voltage is positive, the output voltage is a positive value, when the input voltage is negative, the output voltage is a negative value. The magnitude of the output voltage is a property of the operational amplifier and its power supply. When used with a ±15 V power supply and a 741C operational amplifier, Vsat+ is approximately 13.6 V and Vsat- is approximately -14.3 V.

Control point may refer to:

• Control point (mathematics), a special function defined piecewise by polynomials
• Control point (rail), a form of technical terminology

Rosewill is a computer hardware manufacturer based in City of Industry, California. Rosewill maintains a full line of computer products, such as graphics cards and computer cases. It is a house label of Newegg.com.

Products

• Graphics cards
• Computer monitors
• RAM chips
• Optical disk drives and burners
• Power Supply units
• Desktop PC cases
  
• Flash Memory
• Keyboards and Mice

External links

• Rosewill’s site