bluuebunny/crossref_metadata_2025 huggingface dataset:
3rd International Congress on Acoustics
Authors: Beyer R. T.
Published: January 2009

In the summer of 1958, when I attended a Soviet acoustics meeting in Moscow, I made the acquaintance of Konstantin Naugolnykh, a student at the Acoustics Institute in Moscow. Naugolnykh was characterized by his youth, his good English, and his overriding interest in nonlinear acoustics, which prompted him in conversation to bore straight through his listener in pursuit of an answer to any physical or mathematical problem in the field.
Fuel cells: History, operation, and applications
Authors: Douglas David L. , Liebhafsky Herman A.
Published: January 2009

A fuel cell may be defined as an electrochemical cell in which the chemical energy of a conventional fuel is converted directly and usefully into electrical energy. By way of emphasis some parts of this definition merit further mention. The fuel cell does not differ fundamentally in its operation from primary cells with which we are all familiar; e.g., the Leclanché and mercuric-oxide-zinc dry cells. Use of a conventional fuel which is continuously fed to the anode, rather than an expensive metallic “fuel” such as zinc, is a distinguishing feature of the fuel cell. The category of conventional fuels includes the fossil fuels or substances readily derived from them. Hydrogen qualifies if it is sufficiently cheap; i.e., impure. Similarly, under our definition, oxygen or air is the only oxidant used in fuel cells and it too is fed continuously, but to the cathode.
The foundations of mechanics and thermodynamics
Authors: Kearsley E. A. , Green M. S.
Published: January 2009

On October 21-23, 1959, a Conference on the Foundations of Mechanics and Thermodynamics was held at the Cosmos Club in Washington, D.C. The idea for this conference arose at a series of informal discussions at the National Bureau of Standards among workers in the fields of continuum mechanics and statistical mechanics. Although these subjects can both be classed as branches of mechanics, associated with each a vocabulary and mode of thinking have developed such that the relationship between these disciplines is only vaguely discernible. The conference was designed to shed a little light on this problem, in particular by exploring and comparing the foundations and premises at the heart of each.
Plowshare: A program for the peaceful uses of nuclear explosives
Authors: Lombard David B.
Published: January 2009

The development of thermonuclear weapons in recent years has placed within the grasp of mankind a new, cheap, and almost inexhaustible source of energy. The principal ingredient in thermonuclear reactions is deuterium, a heavy isotope of hydrogen. Deuterium occurs naturally wherever hydrogen is found, since about 0.015 percent of all hydrogen is the heavy isotope, H2. Although the percentage seems low, the total amount of deuterium is extraordinarily large, and a relatively inexpensive process for extracting the deuterium from natural hydrogen has been invented. The atmosphere and oceans of the earth contain enough thermonuclear fuel to last mankind for millions of years at a thousand times the present rate of energy consumption. But, since thermonuclear energy has so far been available only in explosive form, it has not yet been harnessed for nondestructive purposes. Several major research programs currently under way in the United States and other countries are aimed at developing methods of containing and controlling fusion reactions to permit adapting their power output to conventional power-distribution systems. Substantial progress has been made in this field, but it may be many years before a practical controlled-fusion machine will be a reality.
The cat and the cream
Authors: Pippard A. B.
Published: January 2009

The thoughts that I am going to lay before you this evening are, I am afraid, serious thoughts, but they are not in any sense the distilled wisdom of much anxious pondering. They are more like random jottings all related to one central theme, and I hope you will take them in this spirit and forgive me if some of them seem wrong-headed and none of them profound. I believe that, hidden in what I have to say, there is a message, but what this message is I am not very sure. Perhaps you can see it more clearly. It has something to do with the idea of Progress.
The discovery of electron tunneling into superconductors
Authors: Schmitt Roland W.
Published: January 2009

In August 1960, Ivar Giaever published a discovery about electron tunneling into superconductors; the discovery was elegant and had the esthetic simplicity that makes a scientist wonder why it had not been made before. It is too early to assess the importance of the discovery; it may be recorded as only a small but neat strand of science, or the train of work it has set off may produce a web of new knowledge about solids. Regardless of the final assessment that science makes of it, the discovery was surrounded by novel circumstances that dramatize the unexpected course of discovery.
The teaching of physics in schools
Authors: Clark Norman , Michels A. , Renaud M. A. , Sette D. , Sikjaer S. , Topping J. , Weil L.
Published: January 2009

Our Committee was set up in order to suggest how the physics curricula in schools could be revised. The nature of any revision is obviously determined largely by the ultimate purpose that physics teaching in schools is considered to have. Our own discussions have been based upon our strong belief that physics, the most exact and fundamental of the sciences, is a vital part of modern culture and, as such, a necessary element in the education of all children. There are some who appear to equate science with technology and who advocate the extended or more intensive teaching of science because of its probable contribution to increased material well-being. We are well aware of the economic aspects of technological development and of their importance; nevertheless, the cultural value of science—which is all too often inadequately appreciated—should be the aspect which determines the extent and the nature of the science courses in schools. Modern science has changed not only man's environment but his whole approach to many of the problems which he has to face—and which his predecessors had to face. Science is not only a powerful weapon with which to attack material problems; it provides a new process of thought, and new criteria of credibility and of acceptability of evidence. Philosophy, theology, politics, and economics have all been influenced in differing degrees by science, and the most powerful influences have been the result of the changing picture of natural phenomena that scientific thought has created. In the present context, it cannot be too strongly emphasized that science is one of the humanities. Physics is not a collection of “facts” which can be learned; it is a highly imaginative intellectual structure of concepts that gives a meaningful and creative picture or model of such of man's experience of the world in which he lives as it has yet been possible to integrate into a consistent whole. It is a picture that is constantly being given further detail and some parts of which are occasionally being redrawn. The reasons why physics has a place in a child's education are firstly that the story of the drawing of that picture is a remarkable tribute to the power of the human mind and, secondly, the model of nature that physics provides is a necessary component of any fruitful modem thinking about some of the most important of the perennial problems that man has to attempt to solve as a social being.
15th Calorimetry Conference
Authors: Osborne Darrell W.
Published: January 2009

The fifteenth annual Calorimetry Conference was held September 7-10 at Gatlinburg, Tennessee, with Oak Ridge National Laboratory acting as host and J. P. McCullough (Petroleum Thermodynamics Laboratory, Bureau of Mines) serving as chairman. In the pleasant surroundings of the Great Smoky Mountains 106 calorimetrists from the United States, Canada, and Europe heard and discussed 31 technical papers on recent work on many phases of calorimetry and engaged in informal discussions of calorimetric problems. Among the topics discussed were calorimetry at temperatures as low as 0.1°K and as high as 2800 °K, precision reaction and bomb calorimetry, solution calorimetry, applications of calorimetry to solid-state problems, applications of calorimetry to radiation dosimetry, improvements in temperature-measuring devices, and data processing by digital computers. At the Conference banquet ORNL Director A. M. Weinberg shared his experiences and observations on a recent trip to Russia with the chairman of the US Atomic Energy Commission, illustrating his talk with a number of interesting slides. D. W. Osborne (Argonne National Laboratory) was program chairman, and R. H. Busey (ORNL) was local arrangements chairman.
The fourth dimension in science education
Authors: Kovach Ladis D.
Published: January 2009

In the March 1960 issue of Physics Today there was a letter to the editor written by David Redfield of Fairview Park, Ohio. The first part of this letter reads as follows: “The symposium papers in the January issue of Physics Today deal with the role of the physicist in a number of industries. When considered together with other similar articles, they represent a widespread desire for more physicists to direct their efforts toward a multitude of related fields. In view, however, of a small number of physicists in this country (the first article in the same issue indicates that there are less than 20 000), these papers raise a question of paramount importance to physics and, ultimately, to these other fields as well, ‘What about physics?’ That is to say, if physicists shift into the many neighboring fields in response to the demands from these fields, who will be left to do physics?”
Strong interactions
Authors: Helmholz A. C.
Published: January 2009

A Topical Conference on Strong Interactions took place on December 27, 28, and 29, 1960 at the Department of Physics of the University of California in Berkeley. The Conference overlapped by one day the regular Pacific Coast Meeting of the American Physical Society. This meeting was sponsored by the American Physical Society; financial support was generously provided by the Atomic Energy Commission and by the Air Force Office of Scientific Research.
Coherence properties of electromagnetic radiation
Authors: O'Neill E. L. , Bradley L. C.
Published: January 2009

During the last week of June 1960, a three-day conference on the coherence properties of electromagnetic radiation was held on the campus of the University of Rochester. Sponsored by the US Air Force, the University of Rochester, and the Optical Society of America, the purpose of the conference was to bring together optical and atomic physicists from this country and abroad to discuss problems of common interest dealing with the question of coherence throughout the electromagnetic spectrum. To a large extent motivation was supplied by a number of controversial and surprising developments in widely separated branches of physics within the last decade. Certainly much of the attention paid to questions of coherence after so many years of its having lain dormant is due in no small measure to the now famous Brown-Twiss experiment (1955) on the correlation in fluctuations of the output currents of two photoelectric detectors exposed to mutually coherent fields of light. The controversy that followed demonstrated clearly the lack of understanding of the statistical properties inherent in the emission, propagation, and detection of radiation. Whether or not one chose to explain the correlation as a natural tendency for bosons to clump or a natural interference effect among Fourier components in the finite spectral width of every natural source (or both) seemed at first to be a question of taste.
Science doctorates for high-energy physics
Authors: Mills Thomas J.
Published: January 2009

In October 1960, George B. Kistiakowsky, the Special Assistant to the President for Science and Technology, requested the National Science Foundation to develop data on the manpower needed in connection with a proposed high-energy physics program in October, 1960. Specifically, the Foundation was requested to assist in (1) developing “a projection of scientific and engineering manpower needs in high-energy physics over the ten-year period, taking into full account…the national program…through an extension of the study conducted by the Technical Committee on High-Energy Physics…;” (2) “authoritative studies and projection of the likely supply of scientific and engineering manpower over the next ten years;” and (3) “reconciliation of projections of both the manpower needs of high-energy physics and the likely supply of manpower….”
Organic semiconductors
Authors: Brophy James J.
Published: January 2009

In modern science and technology it is not unusual for a research activity to involve more than one scientific discipline. Among the newer research endeavors, perhaps none demonstrates such a dual character more clearly than the field of organic semiconductors, which deeply involves both semiconductor physics and organic chemistry. One result of this dichotomy is that there exists no common forum where research results can be presented and discussed by both physicists and organic chemists. Similarly, it is difficult for industrial organizations in electronics, chemical, and semiconductor activities to learn the latest information concerning rapidly expanding research on organic semiconductors.
Space-time coupling in femtosecond pulse shaping and its effects on coherent control
Authors: Frei F. , Galler A. , Feurer T.
Published: January 2009

We present a Fourier optical analysis of a typical femtosecond pulse shaping apparatus and derive analytic expressions for the space-time dependence of the emerging waveform after the pulse shaper and in the focal volume of an additional focusing element. For both geometries the results are verified experimentally. Hereafter, we analyze the influence of space-time coupling on nonlinear processes, specifically second harmonic generation, resonant interaction with an atomic three-level system, and resonant excitation of a diatomic molecule.
Karl Compton and American physics
Authors: Harrison George R.
Published: January 2009

My pleasure in taking part in these exercises, in which we dedicate the Karl Taylor Compton Board Room of the American Institute of Physics, is heightened by the opportunity it gives to look back once again over the years when Karl Compton was one of us, and among physicists, in human stature, the greatest. Though I do not think the old days were any better than today's, or even so good, it is pleasant to think back to the happy youthful years of American physics, when papers in The Physical Review were less likely to have as many as seven authors, and better yet, when they never failed to appear because of some secret classification. Those were the days when the name of K. T. Compton blazed high in the firmament of electronics.
Physics in Poland and Russia
Authors: Hughes Donald J.
Published: January 2009

This past summer I spent a very busy month in a manner I hardly would have predicted a few years ago—visiting Polish and Soviet scientists, accompanied by my wife, as a guest of their governments. The trip was unusual in that I was not attending a conference, as has been true for most visits of US physicists, but was lecturing and consulting on an individual basis. The resulting informality meant that I was able to learn about a wide variety of physics research and to talk at length to many individuals. As the Russian visit was preceded by two weeks in Poland, I had a chance to learn much about the Soviet work from within, so to speak. Actually, the freedom of discussion in Poland helped to prepare me, in a valuable way, for uncovering details of developments after I reached Russia.
Neutron interactions with the nucleus
Authors: Rae E. R.
Published: January 2009

The International Conference on Neutron Interactions with the Nucleus was held at Columbia University, New York, from the 9th through the 13th of September, 1957, and attracted about 300 delegates from 13 countries including the Soviet Union. Professor I. I. Rabi, who presided, pointed out in his opening speech that 26 years ago the neutron was unknown, and 50 years ago even the nucleus was unknown, and yet today here were 300 scientists from all parts of the world gathered to discuss the interactions between these two entities. As if to stress the importance of neutron reactions in the modern world, the proceedings were then interrupted for a few minutes by the deafening noise of the New York air-raid warning system which was being tested that morning.
High school physics…a report of the Joint Committee on High School Teaching Materials
Authors: Michels Walter C.
Published: January 2009

Anyone who doubts the serious concern of the scientific community about the state of the teaching of mathematics and science in the secondary schools will be reassured, even if not completely comforted, by viewing a list of the activities now being carried forward by professional societies. A recent summary, issued by the Science Teaching Improvement Program of the American Association for the Advancement of Science, includes reports of such activities by 24 distinct and separate groups during the past six months. Any review of the growing literature on the subject indicates that physicists have been much slower in coming to grips with this nationally important problem than have their colleagues in chemistry, in mathematics, and in related fields. Although we cannot yet be proud of our record, the last two years have been marked by growing interest on the part of physicists in general and of the American Institute of Physics and its member societies in particular.
The impact of modern physics on engineering education
Authors: Everitt W. L.
Published: January 2009

Research in modern physics has had for engineering a double impact: on the one hand dramatic and public, yet apparently remote; on the other diffuse and specialized, a process of infiltration from pure science. In engineering neither salient has quite been recognized for what it was.
Teaching physics in Java
Authors: Dickinson W. C.
Published: January 2009

It was more than two years ago, the summer of 1954, over after-dinner coffee at the home of friends in Los Alamos, New Mexico. Our host sighed with obvious relief, “I pictured you, Bill, going to Indonesia to teach physics in a grass hut to students dressed in loin cloths. Now I feel much better!”
The urge to instrument
Authors: Cowan Donald A.
Published: January 2009

The empirical nature of current physical thought has often been called into question by our colleagues in epistemology. The implication of their charges is that we physicists are progressively constructing a set of dogmas so highly abstracted from experience as to be unreal. The complexities of the question preclude any simple answer, but some of its grosser aspects will submit to evidence.
Dimensions units and standards
Authors: McNish A. G.
Published: January 2009

What I wish to set forth here is somewhat in the nature of a sermon, and, as a sermon it should be based upon some text.
Electron theory: Description and analogy
Authors: Oppenheimer J. Robert
Published: January 2009

It is a very special sort of privilege to give this lecture in honor and in memory of Carlson who was, for many of us, both a friend and a colleague. It is certainly appropriate that, as we mourn his loss, we try, as well as we can, to do the kind of thing that he did when he was with us, that he would approve and did approve in his life. It is, of course, also a great pleasure for me to be here in Ames, at a growing and already very famous center of study in many fields, including physics, Carlson's specialty.
Report: NBS Technical Advisory Committee for Mathematics
Authors: Taub A. H.
Published: January 2009

The National Bureau of Standards Technical Advisory Committee for Mathematics has reviewed the work of the Applied Mathematics Division of the Bureau (Division 11) and finds that in spite of the difficulty this division is having in maintaining its present staff and acquiring new staff, it is providing very excellent mathematical, computational, and statistical services to other agencies of the government as well as to other Bureau divisions. The four sections of Division 11, Numerical Analysis Section (11.01), the Computation Laboratory (11.02), the Statistical Engineering Laboratory (11.03), and the Mathematical Physics Section (11.04), have interesting, useful, and imaginative research and training programs which make them effective organizations for the discharge of their responsibilities.
Physics course on TV
Authors: White Harvey E.
Published: January 2009

Because of the fact that the population of our nation is growing more rapidly today than ever before, the educational institutions throughout the country are confronted with increasingly difficult problems concerning the education of our youth. Not only are most of our physical plants overflowing with students, but there is a vital shortage of good teachers to teach them. Some have said, “Raise the teachers' wages and you'll fill your teacher needs.” True, teachers' salaries are considerably below what they should be in comparison with many other professions, but raising their salaries alone will not solve the problem. It is certain that industry and government would raise their salaries to keep valuable men and lure them back from teaching.
The Los Angeles School-Industry Science Program
Authors: Van Atta L. C.
Published: January 2009

It was only a few years ago that scientists and engineers in general began to awaken to the seriousness of a problem that had long been the exclusive and unrelieved burden of high-school teachers and administrators. The problem is to provide improved secondary-school instruction in contemporary science and mathematics to increasing numbers of students. This must be accomplished in spite of many difficulties, principal among which are the severe restrictions in hiring and keeping competent teachers. In the face of this serious secondary-school situation, there has been a striking development that offers a basis for real hope.
Physics instruction in California high schools
Authors: McRary Willard L.
Published: January 2009

Accreditation of California high schools by the University of California has as its purpose the designation of those high schools whose quality of instruction and standards of grading are such that their graduates are admissible to the University solely on the basis of their high-school grades. At the time of initial accreditation, and before the collegiate performance of the school's graduates is known, the school is visited and its college preparatory functions studied. Among the college preparatory courses, the laboratory science offerings stand out as being generally representative of the over-all quality of instruction of a particular school, and thus have been scrutinized most carefully in examining applicant schools. Subsequent retention of a school on the accredited list is conditional on continuing satisfactory performance of the school's graduates in college work.
Dedication week at General Atomic
Authors: Stern Martin O.
Published: January 2009

Some random impressions of the week-long dedication program at General Atomic include the following: The talks had only the scientific approach as their unifying aspect; except for this, they had considerable range and diversity. There was the counterpoint of several different fields—physics, chemistry, metallurgy, even philosophy—and the harmony of different motivations, from the “purest” (philosophy of science and epistemology) to the immediately applicable (reactor engineering). This was appropriate, since the laboratory tries to encourage free interchange between disciplines and has the words “pure and applied” in its title. Further, the extremes of speakers' ages were striking, spanning, I believe, 28 to 75. There seemed to be little correlation between age and type of subject matter, the latter ranging from thoughts distilled over a period of many years to controversial theories on phenomena much discussed at this very moment.
C
12
as a basis for a unified scale of nuclidic masses and atomic weights
Authors: Kohman T. P. , Mattauch J. H. E. , Wapstra A. H.
Published: January 2009

There exist at present three scales of atomic masses or weights: (1) the absolute scale based on the gram, (2) that defined by taking the mass of one atom of the nuclide O16 equal to 16 units (the “physical scale” of “atomic masses” or “nuclidic masses”), and (3) that taking the average atomic mass of the isotope mixture of “natural” oxygen as 16 units (the “chemical scale” of “atomic weights”). Of these, only the last two are in common and extensive use. The chemical scale is indefinite to the extent of the variation in the average atomic mass of oxygen from various natural sources (some IS parts per million) resulting from variations in the relative proportions of O16, O17, and O18.
A glimpse of physics teaching equipment at the University of Moscow
Authors: Brown Sanborn C.
Published: January 2009

We all have an inherent distrust for a traveler who spends ten days in a country and thereafter poses as an expert on all phases of the country he so briefly visited. However, since I have been concerned with undergraduate physics education both here and abroad for some time,* my impressions of the methods of the University of Moscow in this area may be of more than casual interest. This report is based on my own observations and on the answers to many questions which I had the opportunity to ask both of students and teachers during the recent Second All-Union Conference on Gaseous Electronics held in Moscow from October 1 to October 13.
Thermoelectricity
Authors: Lieberman David S.
Published: January 2009

Following within two weeks the Rochester International Conference on Semiconductors, the US Naval Research Laboratory conducted a Conference on Thermoelectricity on September 3 and 4, 1958, in the Department of Interior auditorium in Washington, D.C. More than 450 scientists and engineers from university, government, and industrial laboratories attended. The conference had as its primary goal the exploration of “problems in physics, chemistry, and engineering related to the development of thermoelectric materials”. Although the conference was “prompted by military interest in thermoelectricity”, it was an open technical meeting. As will be seen below, the program was concerned primarily with basic research on materials for both power generation and cooling and only a few papers were devoted in any way to specific applications or the design of devices.
The January 1959 AAPT apparatus competition
Authors: Robinson Howard A.
Published: January 2009

The joint meeting of the AAPT and the APS held in New York from January 29th through 31st was significant for a variety of events. Among these was an Apparatus Competition, held under the auspices of the Committee on Apparatus for Educational Institutions of the AAPT, which drew not only some one hundred and ten entries but also the interest of large numbers of visitors. Because of space limitations, it was possible to accept only sixty-odd entries, but this number included two from abroad, a few from American high schools, and one from an industrial research laboratory. The great majority, as was perhaps to be expected, came from American college and university departments of physics.
In commemoration of Wolfgang Pauli
Authors: Fierz Marcus E. , Weisskopf Victor F.
Published: January 2009

A memorial service for W. Pauli, whose death on the 15th of December saddened the world of physics, was held at Fraumünster in Zürich, Switzerland, on Saturday, December 20, 1958. Among those who came to pay their last respects were Prof. Fierz, whose address is printed in translation below, and Prof. Weisskopf, whose words of tribute appear on p. 19. A former assistant to Pauli (1936–40), Marcus Fierz is professor of theoretical physics at the University of Basle and is editor of Helvetica Physica Acta. Victor Weisskopf, Pauli's collaborator in Zürich from 1933 to 1936, is professor of physics at the Massachusetts Institute of Technology. He flew to Switzerland to attend the memorial service as a representative of the National Academy of Sciences.
Elementary particles
Authors: Lee T. D.
Published: January 2009

The urge and the interest to find those ultimate elements in terms of which everything else is made of are almost as old as the human civilization. However, as our knowledge increases what were thought to be elementary may turn out to be composites. Consequently, the class of these supposedly fundamental elements changes with time. Such was, for example, the periodic table of atoms in the last century. Today we know that all different molecules, atoms, and nuclei are complexes resulting from the existence and the interactions of some thirty particles which are called “elementary particles”.
Correlation between structure, dielectric, and ferroelectric properties in BiFeO3–LaMnO3 solid solution thin films
Authors: Lahmar Abdelilah , Habouti Salah , Solterbeck Claus-Henning , Es-Souni Mohammed , Elouadi Brahim
Published: January 2009

Chemical solution processed BiFeO3 thin films usually show high leakage currents and poor ferroelectric properties. The optimizations of processing conditions and doping with appropriate elements have been among the most promising strategies to enhance the overall properties of BiFeO3 thin films. However, detailed studies on the effects of doping elements on the structure and through it on the properties are still lacking. In this work we investigate the interplay between structure and dielectric-electric-ferroelectric properties of BiFeO3–LaMnO3 [Bi1−xLaxFe1−xMnxO3 (0≤x≤0.1)] solid solution thin films grown on Pt-terminated silicon substrates. The BiFeO3–LaMnO3 system is shown to undergo a structural transition from monoclinic to orthorhombic-tetragonal with various degrees of orthorhombic distortion. All LMO-containing films show a Debye-like dielectric relaxation with the activation energy of 0.90 eV. Both dielectric relaxation and leakage current mechanisms were interpreted in terms of ionized oxygen vacancy hopping. On the basis of comparative studies on individual doping with La and Mn it is shown that Mn is responsible for the dielectric anomaly and structural transition whereas La alone seems to stabilize the perovskite structure. A correlation between the degree of orthorhombic distortion, leakage current, and polarization properties was also found, with a minimum of leakage current and fairly high polarization at the highest distortion.
Influence of annealing temperature and thickness of a CoFeB middle layer on the tunnel magnetoresistance of MgO based double barrier magnetic tunnel junctions
Authors: Reinartz A. , Schmalhorst J. , Reiss G.
Published: January 2009

Magnetic tunnel junctions with two MgO barriers separated by a free CoFeB middle electrode have been investigated. As compared to single barrier junctions, the magnetoresistance increase due to annealing was smaller for these systems. The Néel coupling induced hysteresis shift of the middle electrode decreased, while coercivity and exchange bias field of the pinned ferromagnetic layers increased by increasing annealing temperature. For decreasing thickness of the middle electrode we observed that the contribution of the magnetoresistance of the upper barrier decreases probably due to the islandlike growth mode of CoFeB on MgO. Besides we found an increasing hysteresis shift of the middle electrode and additional dips in the major loops caused by magnetic interactions of the free middle electrode with the top pinned layer.
Laser ultrasonics and neural networks for the characterization of thin isotropic plates
Authors: Lefevre F. , Jenot F. , Ouaftouh M. , Duquennoy M. , Poussot P. , Ourak M.
Published: January 2009

Nondestructive testing has been performed on a thin copper plate. Lamb waves were generated and studied with a noncontact method, using a laser ultrasonic setup. A two-dimensional Fourier transform technique has been employed to obtain the dispersion curves, revealing numerous symmetric and antisymmetric modes. The inverse problem, in other words, the determination of the thickness and the elastic constants of the tested plate, has been solved by means of a feed-forward neural network. These parameters were then evaluated simultaneously, the dispersion curves being entirely fitted. The experimental results show good agreement with the theoretical model. This inversion method was found to be prompt and easy to automate.
Influence of nitrogen doping on growth rate and texture evolution of chemical vapor deposition diamond films
Authors: Liu T. , Raabe D.
Published: January 2009

Chemical vapor deposition (CVD) diamond films were prepared using a variation in nitrogen addition into the gas source admixture by a direct current CVD method. The influence of nitrogen addition on the crystallographic texture and grain shape evolution in heteroepitaxial polycrystalline diamond films was investigated using high-resolution electron backscattering diffraction and x-ray diffraction. The analysis reveals that an addition of 1.5% N2 to the CH4 gas flow leads to a strong enhancement in a {110} fiber texture. The phenomenon is discussed in terms of a competitive growth selection mechanism.
Nonpolar GaN grown on Si by hydride vapor phase epitaxy using anodized Al nanomask
Authors: Polyakov A. Y. , Markov A. V. , Mezhennyi M. V. , Govorkov A. V. , Pavlov V. F. , Smirnov N. B. , Donskov A. A. , D’yakonov L. I. , Kozlova Y. P. , Malakhov S. S. , Yugova T. G. , Osinsky V. I. , Gorokh G. G. , Lyahova N. N. , Mityukhlyaev V. B. , Pearton S. J.
Published: January 2009

GaN growth by the hydride vapor phase technique on (100) Si substrates masked by porous Al anodic oxide is described. The masks were prepared by vacuum deposition of Al with subsequent anodic oxidation in dilute sorrel acid. The grown GaN layer is nonpolar, with (112¯0) a-orientation and a full width at half maximum of the (112¯0) reflection below 500 arc sec and showing small anisotropy. This result is comparable with the results obtained for a-GaN growth using selective epitaxy or advanced buffer growth routines. Microcathodoluminescence spectra of the grown films confirm a low density of stacking faults. Possible growth mechanisms are discussed.
High thermoelectric power factor in alloys based on CoSi
Authors: Skoug E. , Zhou C. , Pei Y. , Morelli D. T.
Published: January 2009

We have investigated the thermoelectric properties of alloys of composition CoSi1−xGex for 0≤x≤0.5. These alloys display Seebeck coefficient in the range of −80 to −100 μV K−1 at room temperature. Despite the rather high Seebeck coefficients, the electrical resistivity of these alloys is metallic in nature. Alloying on the Ge site strongly reduces the lattice thermal conductivity. The combination of high Seebeck coefficient and metallic resistivity leads to very high thermoelectric power factor in these alloys, with the best sample exhibiting a power factor higher than that of state of the art bismuth telluride-based thermoelectric alloys at room temperature.
Growth dynamics of C60 thin films: Effect of molecular structure
Authors: Yim S. , Jones T. S.
Published: January 2009

The surface morphology and growth behavior of fullerene thin films have been studied by atomic force microscopy and height difference correlation function analysis. In contrast to the large growth exponents (β) previously reported for other organic semiconductor thin-film materials, a relatively small β value of 0.39±0.10 was determined. Simulations of (1+1)-dimensional surface lateral diffusion models indicate that the evolution of deep grain boundaries leads to a rapid increase in β. We suggest that the commonly observed large β values for organic thin films are due to their intrinsically anisotropic molecular structures and hence different stacking directions between crystallite domains.
Competitive surface effects of oxygen and water on UV photoresponse of ZnO nanowires
Authors: Li Yanbo , Della Valle Florent , Simonnet Mathieu , Yamada Ichiro , Delaunay Jean-Jacques
Published: January 2009

UV photoresponse of ZnO nanowires is measured in air under different humidity conditions to study the competitive surface effects of oxygen and water vapor. During UV illumination, it was found that the current decreases gradually under high humidity, whereas the current increases under low humidity. In the recovery phase, a change of two to three orders of magnitude in the decay time is observed by varying the humidity. A model that takes into account the solid-state process of photocarrier generation/recombination and the competitive surface effects of oxygen/water is proposed to explain the observed variations in photoresponse under different humidity conditions.
Dynamic gene expression is required for anterior regionalization in a spider
Authors: Pechmann Matthias , McGregor Alistair P. , Schwager Evelyn E. , Feitosa Natália M. , Damen Wim G. M.
Published: January 2009

Patterning of a multicellular embryo requires precise spatiotemporal control of gene expression during development. The gradient of the morphogen bicoid regulates anterior regionalization in the syncytial blastoderm of
Drosophila
. However many arthropod embryos develop from a cellular blastoderm that does not allow the formation of transcription factor gradients. Here we show that correct anterior development of the cellularized embryo of the spider
Achaearanea tepidariorum
requires an anterior-to-posterior wave of dynamic gene expression for positioning the stripes of
hairy
,
hedgehog
, and
orthodenticle
expression. Surprisingly, this dynamic repositioning of the expression of these segmentation genes is blocked in
orthodenticle
pRNAi
embryos and no anterior structures are specified in those embryos. Our data suggest that dynamic gene expression across a field of cells is required for anterior regionalization in spiders and provides an explanation for the problem of how positional values for anterior segmentation genes are specified via a morphogen-independent mechanism across a field of cells.
Recordkeeping alters economic history by promoting reciprocity
Authors: Basu Sudipta , Dickhaut John , Hecht Gary , Towry Kristy , Waymire Gregory
Published: January 2009

We experimentally demonstrate a causal link between recordkeeping and reciprocal exchange. Recordkeeping improves memory of past interactions in a complex exchange environment, which promotes reputation formation and decision coordination. Economies with recordkeeping exhibit a beneficially altered economic history where the risks of exchanging with strangers are substantially lessened. Our findings are consistent with prior assertions that complex and extensive reciprocity requires sophisticated memory to store information on past transactions. We offer insights on this research by scientifically demonstrating that reciprocity can be facilitated by information storage external to the brain. This is consistent with the archaeological record, which suggests that prehistoric transaction records and the invention of writing for recordkeeping were linked to increased complexity in human interaction.
Principal component analysis of native ensembles of biomolecular structures (PCA_NEST): insights into functional dynamics
Authors: Yang Lee-Wei , Eyal Eran , Bahar Ivet , Kitao Akio
Published: January 2009

Motivation: To efficiently analyze the ‘native ensemble of conformations’ accessible to proteins near their folded state and to extract essential information from observed distributions of conformations, reliable mathematical methods and computational tools are needed.

Result: Examination of 24 pairs of structures determined by both NMR and X-ray reveals that the differences in the dynamics of the same protein resolved by the two techniques can be tracked to the most robust low frequency modes elucidated by principal component analysis (PCA) of NMR models. The active sites of enzymes are found to be highly constrained in these PCA modes. Furthermore, the residues predicted to be highly immobile are shown to be evolutionarily conserved, lending support to a PCA-based identification of potential functional sites. An online tool, PCA_NEST, is designed to derive the principal modes of conformational changes from structural ensembles resolved by experiments or generated by computations.

Availability:  http://ignm.ccbb.pitt.edu/oPCA_Online.htm

Contact:  lwy1@iam.u-tokyo.ac.jp

Supplementary information:  Supplementary data are available at Bioinformatics online.
Recruitment in a changing environment: the 2000s North Sea herring recruitment failure
Authors: Payne Mark R. , Hatfield Emma M. C. , Dickey-Collas Mark , Falkenhaug Tone , Gallego Alejandro , Gröger Joachim , Licandro Priscilla , Llope Marcos , Munk Peter , Röckmann Christine , Schmidt Jörn O. , Nash Richard D. M.
Published: January 2009

Payne, M. R., Hatfield, E. M. C., Dickey-Collas, M., Falkenhaug, T., Gallego, A., Gröger, J., Licandro, P., Llope, M., Munk, P., Röckmann, C., Schmidt, J. O., and Nash, R. D. M. 2009. Recruitment in a changing environment: the 2000s North Sea herring recruitment failure. – ICES Journal of Marine Science, 66: 272–277. Environmentally induced change appears to be impacting the recruitment of North Sea herring (Clupea harengus). Despite simultaneously having a large adult population, historically low exploitation, and Marine Stewardship Council accreditation (implying sustainability), there have been an unprecedented 6 sequential years of poor juvenile production (recruitment). Analysis suggests that the poor recruitment arises during the larval overwintering phase, with recent survival rates greatly reduced. Contemporary warming of the North Sea has caused significant changes in the plankton community, and a recently identified regime shift around 2000 shows close temporal agreement with the reduced larval survival. It is, therefore, possible that we are observing the first consequences of this planktonic change for higher trophic levels. There is no indication of a recovery in recruitment in the short term. Fishing mortality is currently outside the agreed management plan, and forecasts show a high risk of the stock moving outside safe biological limits soon, potentially precipitating another collapse of the stock. However, bringing the realized fishing mortality back in line with the management plan would likely alleviate the problem. This illustrates again that recruitment is influenced by more than just spawning-stock biomass, and that changes in other factors can be of equal, or even greater, importance. In such dynamically changing environments, recent management success does not necessarily guarantee future sustainability.
Soil–atmosphere exchange of greenhouse gases in a Eucalyptus marginata woodland, a clover‐grass pasture, and Pinus radiata and Eucalyptus globulus plantations
Authors: LIVESLEY S. J. , KIESE R. , MIEHLE P. , WESTON C. J. , BUTTERBACH‐BAHL K. , ARNDT S. K.
Published: January 2009

Soils provide the largest terrestrial carbon store, the largest atmospheric CO2 source, the largest terrestrial N2O source and the largest terrestrial CH4 sink, as mediated through root and soil microbial processes. A change in land use or management can alter these soil processes such that net greenhouse gas exchange may increase or decrease. We measured soil–atmosphere exchange of CO2, N2O and CH4 in four adjacent land‐use systems (native eucalypt woodland, clover‐grass pasture, Pinus radiata and Eucalyptus globulus plantation) for short, but continuous, periods between October 2005 and June 2006 using an automated trace gas measurement system near Albany in southwest Western Australia. Mean N2O emission in the pasture was 26.6 μg N m−2 h−1, significantly greater than in the natural and managed forests (< 2.0 μg N m−2 h−1). N2O emission from pasture soil increased after rainfall events (up to 100 μg N m−2 h−1) and as soil water content increased into winter, whereas no soil water response was detected in the forest systems. Gross nitrification through 15N isotope dilution in all land‐use systems was small at water holding capacity < 30%, and under optimum soil water conditions gross nitrification ranged between < 0.1 and 1.0 mg N kg−1 h−1, being least in the native woodland/eucalypt plantation < pine plantation < pasture. Forest soils were a constant CH4 sink, up to −20 μg C m−2 h−1 in the native woodland. Pasture soil was an occasional CH4 source, but weak CH4 sink overall (−3 μg C m−2 h−1). There were no strong correlations (R < 0.4) between CH4 flux and soil moisture or temperature. Soil CO2 emissions (35–55 mg C m−2 h−1) correlated with soil water content (R < 0.5) in all but the E. globulus plantation. Soil N2O emissions from improved pastures can be considerable and comparable with intensively managed, irrigated and fertilised dairy pastures. In all land uses, soil N2O emissions exceeded soil CH4 uptake on a carbon dioxide equivalent basis. Overall, afforestation of improved pastures (i) decreases soil N2O emissions and (ii) increases soil CH4 uptake.
Pulmonary preneoplasia – sequential molecular carcinogenetic events
Authors: Lantuéjoul Sylvie , Salameire Dimitri , Salon Caroline , Brambilla Elisabeth
Published: January 2009

Bronchial and bronchioloalveolar carcinogenesis is a multicentric and multistep process, leading to a sequential accumulation of molecular and genetic abnormalities, mainly due to exposure to tobacco carcinogens. Concomitantly, a series of morphological alterations of normal bronchial or bronchioloalveolar epithelium occur, resulting in preneoplastic and then neoplastic lesions. The three pulmonary preneoplastic changes recognized to date in the lung include bronchial squamous dysplasia andin situcarcinoma, preceding invasive squamous cell carcinoma and basaloid carcinoma, atypical adenomatous hyperplasia, a preneoplastic condition of bronchioloalveolar carcinoma, and diffuse idiopathic pulmonary neuroendocrine cell hyperplasia, a proposed precursor for carcinoid tumours. Although the gradual accumulation of molecular alterations has been widely investigated in bronchial carcinogenesis, with the aim of determining new biomarkers for early lung cancer detection in high‐risk patients and targeted chemoprevention, lung adenocarcinoma pathogenesis has been only recently highlighted, with the recent discovery of epidermal growth factor receptor mutation pathway in non‐smokers. This review focuses on the current status of molecular pathology in lung cancer and pulmonary preneoplastic conditions.
Factors affecting masticatory performance of Japanese children
Authors: OUEIS HASSAN
Published: January 2009

Aim.  The aim of this study was to analyse occlusal parameters and body variables to examine the factors accounting for masticatory performance of Japanese children in relation to adults.

Methods.  Sixty‐six children and 24 adults chewed three pieces of a colour‐changeable chewing gum, separately, for 30 s, 60 s, and 90 s. The colour change was measured at 30 s using L* a* b* colour space system. Biting force, occlusal contact areas, and occlusal pressure were recorded by Dental Prescale. Number of strokes, and the height and weight of the subjects were included in the statistical analysis.

Results.  Within each sample, Student's t‐test revealed significant differences among a* values at the three chewing times in which the value of a* (indicator of red) increased as the length of chewing time increased (P < 0.05). Multiple regression analysis showed that the rate of mandibular movement in preschool children has a significant impact on masticatory performance (P < 0.05). In schoolchildren, the rate of mandibular movement, biting force, and body weight were significant factors (P < 0.05). In adults, occlusal contact area, biting force, and the rate of mandibular movement were the significant factors (P < 0.05).

Conclusion.  Factors affecting masticatory performance differ according to the developmental stage of the individual.