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Ruth Glasner's Averroes' Physics is one of the finest studies on Averroes, one of the best on medieval Aristotelianism, and one of the most important contributions of modern scholarship to understanding the history of medieval science. The present article seeks to make clear what is so special about the work. It first situates Glasner's book in the context of present-day research on Averroes and suggests in what ways it responds to the main desiderata in the field of Averroean studies. It then points to some of the most instructive contributions of the work. In short, thanks to Glasner, we now see Averroes not only as the outstanding explicator of Aristotle, but as a creative scientific mind as well. We now know him much better than he has ever been known., Permit me to begin with my initial assessment, made several years ago, of Ruth Glasner's book, Averroes' Physics: A Turning Point in Medieval Natural Philosophy: (1) This is a work [...]

The article focuses on Gersonides' use of Aristotle's concept of chance (Physics II.4-6) as an investigative tool in his inquiries in the Wars of the Lord. Four examples are studied: Divine providence (Wars IV), the agent that generates animate substances (Wars V.3), the agent of miracles (Wars VI. 2.10), and the creation of the world (Wars VI.1). Gersonides' inquiries involve various applications of the passages on chance in Physics II. In the discussions of providence and of the agent that generates animate substances, Gersonides invokes the criterion of rarity. By negating the possibility that they are generated by chance he shows that the phenomena or events in question are produced by a purposeful efficient cause. In his expositions of the first criterion for distinguishing between the generated and ungenerated and of the creation of the heavens he employs the criterion of rarity to rebut objections to his thesis. In the discussion of the agent of miracles, he applies the distinction between determinate and indeterminate causes: a miracle has a determinate cause and thus cannot be a matter of chance. In his discussion of the generation of the heavenly bodies, Gersonides draws on Aristotle's refutation (Physics II.4) of Democritus's assertion that the heavens were generated 'spontaneously,' whereas animals and plants do not come into existence by chance. He demonstrates, on the basis of their functionality, that the heavens do have an efficient cause., 1. Introduction Ruth Glasner has devoted a number of highly innovative and enlightening studies to Gersonides (1288-1344), with special attention to his empirical and experimental approach to science. She has [...]

While he was in Mantua in 1475, the Italian Jewish philosopher Judah Messer Leon (ca. 1425-1498) wrote a wide commentary on Aristotle's Physics 1-4. As a 'Hebrew Schoolman,' he inserted into this work a number of explicit and implicit references to Latin Scholastic commentaries on the Physics. An examination of the Latin sources quoted explicitly has been given elsewhere. Here, two implicit sources are examined: Paul of Venice's Expositio super octo libros Physicorum necnon super commentum Averrois, and Gaetano de Thiene's Recollectae super octo libros Physicorum Aristotelis. The former was apparently employed by Judah Messer Leon only for the general structure of his work; the latter, by contrast, was widely employed as the direct source of several long passages, although the Latin author was never mentioned by name. Some of these passages, found in Book 1, Parts 1-2 of the commentary (on Aristotle, Physics 184a10-188a8), are listed and examined here. Their close relationship with Gaetano de Thiene's work is shown., Judah Messer Leon (ca. 1425-1498), one of the most important Italian Jewish authors of the fifteenth century, wrote a number of philosophical works; many of them were strongly influenced by [...]

Important features of the new Avicennan physics were available to Hasdai Crescas in al-Tabrizi's commentary on Maimonides' twentyfive premises, a book that he thoroughly exploited for his assault on the Aristotelian world-view. However, in his discussion of the thirteenth premise, which maintains quies media, Crescas chose to ignore al-Tabrizi's arguments, which rest on the concept of mayl or inclination. The article examines the treatments of this premise by Crescas and al-Tabrizi, within the wider context of the transmission of Avicennan physics to Europe. This study furnishes additional evidence for Crescas' lack of interest in some of the new ideas in physics as well as his failure to develop a coherent theory of time and motion. The appraisals of impetus theory by older and newer historians of science are also discussed. An appendix provides some raw evidence for the classification of spiral motion as simple--a view that may have come to Crescas' attention as well., The movement of scientific ideas from one area to another, often crossing political, religious, and social boundaries in the process, is an important topic for research, and has been for [...]

A physics-based, pointwise model is developed to predict crater profiles of multilayer coated carbides after a series of turning experiments. Dissolution and abrasion mechanisms, which are identified to be the dominant wear mechanisms at the crater, are reformulated into a pointwise or local quantity to predict the crater profiles based on the temperature and pressure profiles from finite element (FE) simulations. The crater profiles predicted by the proposed model have to be adjusted, however, due to the creep deformation of the carbide substrate occurring under the machining conditions employed in our experiment. The crater predictions correlate pretty well with the crater profiles experimentally observed in the multilayer (TiN-[Al.sub.2][O.sub.3]-TiCN) coated carbides until the wear front reached the middle of the [Al.sub.2][O.sub.3] layer. At this point, the [Al.sub.2][O.sub.3] coating undergoes the [kappa]-to-[alpha]-phase transformation, which makes the wear prediction difficult due to substantial changes in the thermomechanical properties of the [Al.sub.2][O.sub.3] coating. [DOI: 10.1115/1.4002111]

8:00 CONVERSION OF A PETROLEUM COMBUSTION ENGINE TO HYDROGEN FUEL **, Jeremy Robinson *, Phil Hines *, Alexander Bauer * and Richard Gamble *, Augusta State University, Augusta, GA 30904-2200. [...]

In the following notes I wish to tell the stories of two anonymous Hebrew commentaries on the Physics, which were wrongly identified by Steinschneider. I maintain that both commentaries were written in Spain in the second half of the fifteenth century and that Steinschneider's earlier dating obscured the picture of the development of Hebrew scholarship in the fourteenth and fifteenth centuries. (1) The first text has not been studied before; the second was studied several times, but its confusing structure kept its story from being understood properly., The Commentary attributed by Steinschneider to Moshe Narboni MS Paris BNF heb. 967/1 (IMHM 30339). 108 large densely written folios, Spanish cursive script. (2) Moshe Narboni, the well-known fourteenth-century Jewish [...]

The pseudogap region of the phase diagram is an important unsolved puzzle in the field of high-transition-temperature (high-[T.sub.c]) superconductivity, characterized by anomalous physical properties (1,2). There are open questions about [...]

I am an optimist, the sort we call incorrigible. So for those who know me, there should be no surprise at my title and theme. There is no question in [...]

The creation of atoms of antihydrogen under controlled conditions has opened up a new era in physics with antimatter. We describe the experimental realisation of low energy antihydrogen, via the mixing of carefully prepared clouds of positrons and antiprotons, and some of the progress that has been made in the last few years in characterising properties of the nascent anti-atoms. Ongoing efforts aimed at trapping the anti-atoms in magnetic field minima are discussed. Some of the motivations for undertaking experiments with antihydrogen are presented. Keywords: antihydrogen; CPT; positrons; antiprotons; Penning traps

Chair: Erdem Topsakal, Mississippi State University Vice-chair: Alina Gearbe, University of Southern Mississippi THURSDAY MORNING Amphitheater O10.01 8:30 MICRO-MANUFACTURING Kant Vajpayee The University of Southern Mississippi Evolution in electronics during [...]

Abstract: In this contribution, we present calculations performed for interacting electron systems within a nonperturbative formulation of the cluster theory. Extrapolation of the model to describe the time dependence of [...]

For a closed system that contains an arbitrary pure substance, which can exchange energy as heat and as expansion/compression work, but no particles, with its surroundings, the inexact differential of the reversibly exchanged heat is a differential in two variables. This inexact differential can be turned into an exact one by an integrating factor that, in general, depends on both variables. We identify the general form of the integrating factor as the reciprocal temperature (Clausius' well-known l/T), which is guaranteed to be a valid integrating factor by the second law of thermodynamics, multiplied by an arbitrary function of the implicit adiabat equation [xi](T,V) =constant or [xi](T,P)=constant. In general, we cannot expect that two different equations of state (corresponding to two different substances) predict identical equations for the adiabats. The requirement of having a universal integrating factor thus eliminates the volume-dependent or pressure-dependent integrating factors and leaves only a function of temperature alone: Clausius' integrating factor 1/T. The existence of other integrating factors is rarely mentioned in textbooks; instead, the integrating factor 1/T is usually taken for granted relying on the second law or, occasionally, one finds it 'derived' incorrectly from the first law of thermodynamics alone.

A simple tight-binding model is used to illustrate how the time dependence of a state vector can be obtained from all the eigenvalues and eigenvectors of the Hamiltonian. The behavior of the eigenvalues and eigenvectors is studied for various parameters and allows us to study scatteringlike events, impurity states, and localization in disordered systems.

The classical and quantum mechanical solutions to three simple physical systems are directly compared by using the classical equations of motion to determine a probability density function. This function is compared to the probability density function for the quantum mechanical stationary state with the same energy. The nonclassical behavior of the quantum mechanical systems is thus made more distinct. This comparison allows students to gain experience using probability functions to describe physical systems and to see how the quantum mechanical solutions reduce to classical behavior in the high-energy/short-wavelength limit. [DOI: 10.1119/1.2173280]

Abstract: The band-gap energy, [E.sub.g], of ZnO doped with 0.1 to 2.0 mol% of MnO and sintered at different isothermal sintering temperatures is studied by photopyroelectric spectroscopy in the wavelength [...]

Phase space can be constructed for N equal and distinguishable subsystems that could be probabilistically either weakly correlated or strongly correlated. If they are locally correlated, we expect the Boltzmann-Gibbs entropy [S.sub.BG] = -k [summation over (i) pi] In pi to be extensive, i.e., [S.sub.BG](N) [varies] N for N [right arrow] [ifinity]. In particular, if they are independent, [S.sub.BG] is strictly additive, i.e., [S.sub.BG](N) = N[S.sub.BG](1), [for all]N. However, if the subsystems are globally correlated, we expect, for a vast class of systems, the entropy [S.sub.q] [equivalent to] k[1 - [summation over (i) [p.sup.q.sub.i] ]/(q - 1) (with [S.sub.1] = [S.sub.BG]) for some special value of q [not equal to] 1 to be the one which is extensive [i.e., [S.sub.q](N) [varies] N for N [right arrow] [infinity]]. Another concept which is relevant is strict or asymptotic scale-freedom (or scale-invariance), defined as the situation for which all marginal probabilities of the N-system coincide or asymptotically approach (for N [right arrow] [infinity]) the joint probabilities of the (N - 1)-system. If each subsystem is a binary one, scale-freedom is guaranteed by what we hereafter refer to as the Leibnitz rule, i.e., the sum of two successive joint probabilities of the N-system coincides or asymptotically approaches the corresponding joint probability of the (N - 1)-system. The kinds of interplay of these various concepts are illustrated in several examples. One of them justifies the title of this paper. We conjecture that these mechanisms are deeply related to the very frequent emergence, in natural and artificial complex systems, of scale-free structures and to their connections with nonextensive statistical mechanics. Summarizing, we have shown that, for asymptotically scale-invariant systems, it is [S.sub.q] with q [not equal] 1, and not [S.sub.BG], the entropy which matches standard, clausius-like, prescriptions of classical thermodynamics.

We present analytical results for the lowest order cumulants of a stochastic process described by a Fokker-Planck equation with nonlinear drift, which appears in the description of laser cooling of atoms. We show that, in the limit of small fluctuations, the mean, the variance, and the covariance of the process can be expressed in compact form with the help of the Lambert W function. As an application, we discuss the interplay of noise and nonlinearity far from equilibrium. [DOI: 10.1119/1.1949632]

The concept of light (electromagnetic radiation) outside of the visible spectrum is an abstract concept for students in an introductory science class. When students are presented with demonstrations or experiments meant to explore this portion of the spectrum, the equipment involved often hides the phenomena. A simple modification to a standard, inexpensive web camera (webcam) can take advantage of the sensitivity of the charged-coupled-device (CCD) to the infrared (IR) portion of the spectrum, allowing students to visualize many IR phenomena. This note reports how such a modified webcam can be used in lecture demonstrations and laboratory activities to study infrared phenomena including an IR light emitting diode (LED), the IR component of different light sources, IR spectroscopy, and blackbody radiation. As a final example, the modified camera can be employed to view the charcoal under-drawing of a 'painting' created for this paper and used in our classroom demonstrations. [DOI: 10.1119/1.1900105]

Symplectic integrators very nearly conserve the total energy and are particularly useful when treating long times. We demonstrate some of the properties of these integrators by exploring the structure of first-, second-, and fourth-order symplectic integrators and apply them to the simple harmonic oscillator. We consider numeric, geometric, and analytic aspects of the integrators with particular attention to the computed energies. [DOI: 10.1119/1.2034523]

The relativistic conservation law involving the center of energy is reviewed and illustrated using simple examples from classical electromagnetic theory. It is emphasized that this conservation law is parallel to the conservation laws for energy, linear momentum, and angular momentum, because it arises from the generators of the Poincare group for electromagnetic theory; yet this relativistic law reflecting the continuous flow of energy is not mentioned in text books. The illustrations include situations where external forces are present and are absent. A parallel plate capacitor, a flattened slip-joint solenoid, and two interacting charges are treated. [DOI: 10.1119/1.1900101]

A model of damped oscillations of a variable mass on a spring pendulum, with the mass decreasing at a constant rate is presented. The model includes damping terms that are linear and quadratic in the velocity. The effect of the mass loss rate on the magnitude of the damping parameters is discussed. The model is compared to experimental data obtained with the aid of computer-based laboratory equipment. [DOI: 10.1119/1.1979498]

A spinning ball incident at right angles to a surface bounces at an oblique angle and with reduced spin. Consequently, a spinning ball struck head-on does not rebound along its incident path, which presents a control problem in bat and racquet sports. The rebound angle and spin depend in a nontrivial manner on the coefficient of friction between the ball and the surface and on the elastic properties of the ball and the surface. Values of the normal and tangential coefficients of restitution coefficients are presented for a tennis ball impacting a smooth and a rough surface and on strings of a tennis racquet. The implications for spin generation in tennis are briefly described. [DOI: 10.1119/1.2008299]

When the probability of measuring a particular value of some quantity varies inversely as a power of that value, the quantity is said to follow a power law, also known variously as Zipf's law or the Pareto distribution. Power laws appear widely in physics, biology, earth and planetary sciences, economics and finance, computer science, demography and the social sciences. For instance, the distributions of the sizes of cities, earthquakes, forest fires, solar flares, moon craters and people's personal fortunes all appear to follow power laws. The origin of power-law behaviour has been a topic of debate in the scientific community for more than a century. Here we review some of the empirical evidence for the existence of power-law forms and the theories proposed to explain them.

This paper describes a computer-based physics laboratory apparatus to replace expensive instruments such as high-precision signal generators. This apparatus uses a sound card in a common personal computer to give sinusoidal signals with an accurate frequency that can be programmed to give different frequency signals repeatedly. An experiment on standing waves on an oscillating string uses this apparatus. In conjunction with interactive lab manuals, which have been developed using personal computers in our university, we achieve a complete set of low-cost, accurate, and easy-to-use equipment for teaching a physics laboratory. (c) 2005 American Association of Physics Teachers. [DOI: 10.1119/1.1891169]

We consider a clock paradox where an observer leaves an inertial frame, is accelerated, and after an arbitrary trip returns. We discuss a simple equation that gives an explicit relation in 1 + 1 dimensions between the time elapsed in the inertial frame and the acceleration measured by the accelerating observer during the trip. A non-closed trip with respect to an inertial frame appears closed with respect to another suitable inertial frame. We use this observation to define the differential aging as a function of proper time. The reconstruction problem of special relativity is discussed and it is shown that its solution would allow the construction of an inertial clock. (c) 2005 American Association of Physics Teachers. [DOI: 10.1119/1.1924490]

A simple x-ray fluorescence experiment suitable for graduate and undergraduate laboratories is described. The experiment uses a NaI(T1) x-ray spectrometer, a weak [sup.57Co] radioactive source (~ [10.sup.5] Bq), and medium-Z targets of silver, cadmium, indium, and tin. The [Kappa] x-ray fluorescence yield, [[omega].sub.k], and [Kappa] x-ray production cross section, [[delta].sub.k], are measured for these targets. Accurate results are achieved by adopting a 2[phi] detection geometry and by optimizing target dimensions for this experimental configuration. The experiment can be completed in 4 h and is suitable for student laboratories. (c) 2005 American Association of Physics Teachers. [DOI: 10.1119/1.1881254]

The Pade-Laplace method is an interesting yet relatively unknown method for determining the exponential time constants in a decaying signal. We apply it to data from a simple electronic circuit specifically designed for investigations of signal averaging. Possible decays of the voltage include single, multi-exponential, and predominantly logarithmic. Students in our computer-interfacing course write a LABVIEW program that collects the data and performs the signal averaging. (c) 2005 American Association of Physics Teachers. [DOI: 10.1119/1.1927551]

A simple device for measuring thermal deformations in two-dimensional samples cooled to liquid nitrogen temperatures is described. The measurement consists of adding liquid nitrogen to a transparent quartz tray, and then scanning the sample from the bottom with a flatbed scanner. As a test of the device, the thermal contraction of aluminum from room temperature to 77 K is measured. The application of Gruneisen's approximation leads to good agreement between the calculated and tabulated contraction percentages. (c) 2005 American Association of Physics Teachers. [DOI: 10.1119/1.1949631]

The Takagi-Taupin equations are a set of partial differential equations that are fundamental in the dynamical theory of x-ray diffraction. We show how they can be manipulated to make them suitable for the application of Riemann's method and present in detail the steps leading to their solution. To help readers gain insight into coherent x-ray wave fields, we calculate the intensity distribution of x-ray beams from mono- and polylithic perfect silicon single crystals. As an example of the interplay between wave fields, we illustrate the Pendellosung effect. We did some of the algebraic manipulations and most of the numerical calculations by using Mathematica. (c) 2005 American Association of Physics Teachers. [DOI: 10.1119/1.1891172]

We present a simple circuit that performs Fermi-Dirac integration. The core of the circuit is a differential amplifier that we show is a model of a Fermi-Dirac system. The construction and characterization of the circuit requires students to apply knowledge of device physics, transistor circuit theory, and signal processing. The circuit construction is relatively simple and requires only a few components found in most electronics laboratories. (c) 2005 American Association of Physics Teachers. [DOI: 10.1119/1.1938951]

Some experiments are conveniently performed in the time domain, some in the frequency domain, and some use a hybrid approach. Does the domain make any difference in the ultimate resolution of the experiment? Or can the details of the experiment always be tweaked so that the different approaches give the same answer? We consider a simple optics experiment and consider both time and frequency measurements and take into account the influence of noise, finite dynamic range, attenuation, and the duration of the measurement. (c) 2005 American Association of Physics Teachers. [DOI: 10.1119/1.1891172]

Why is the integrated difference of the kinetic and potential energies the quantity to be minimized in Hamilton's principle? I use simple arguments to convert the problem of finding the path of a particle connecting two points to that of finding the minimum potential energy of a string. The mapping implies that the configuration of a nonstretchable string of variable tension corresponds to the spatial path dictated by the principle of least action; that of a stretchable string in space-time is the one dictated by Hamilton's principle. This correspondence provides the answer to the question. (c) 2005 American Association of Physics Teachers. [DOI: 10.1119/1.1930887]

This Resource Letter provides a guide to literature on the Manhattan Project and related nuclear research. Books and journal articles are cited for the following topics: general works, technical works, biographical and autobiographical works, the German nuclear program, and technical papers of historical interest. A list of videos and websites dealing with the Manhattan Project, nuclear weapons, and nuclear issues is also given. (c) 2005 American Association of Physics Teachers. [DOI 10.1119/1.1949629]

A block sliding down an inclined plane normally accelerates. However, if the friction force increases with speed, then the block can slide at a constant terminal speed in a manner similar to the fall of an object through a fluid. Measurements of the increase in the coefficient of friction for tennis ball cloth sliding on a smooth surface are described over speeds varying by a factor of 9000. For the low speed measurements, the ball cloth was attached to the bottom of a weighted box and pulled along a horizontal surface by a constant horizontal force. Results at higher speeds were obtained by bouncing a tennis ball off the surface. (c) 2005 American Association of Physics Teachers. [DOI: 10.1119/1.1891174]