bluuebunny/crossref_metadata_2025 huggingface dataset:
Diabetic Muscle Infarction in Association with Terlipressin Therapy: A Case Report
Authors: Chang Yu‐Hung , Yen Feng‐Chieh , Hsieh Ming‐Chia , Lin Kun‐Der , Shin Shyi‐Jang , Hsin Shih‐Chieh
Published: April 2009

Diabetic muscle infarction (DMI) is a rare complication that often exists in long‐standing diabetic patients. Clinically, it presents with pain, swelling and sometimes a palpable mass, and is often misdiagnosed as soft tissue infection. The athogenesis of DMI is uncertain. We present the case of a type 2 diabetic patient with liver cirrhosis who was diagnosed with muscle infarction after being treated with terlipressin for gastrointestinal bleeding. This 45‐year‐old male complained of increasing pain in his right posterior thigh after treatment with terlipressin for 2 days. He was initially diagnosed with soft tissue infection, but he responded poorly to antibiotic treatment. Magnetic resonance imaging suggested acute muscle infarction. We performed a muscle biopsy and the pathologist reported that the muscle was necrotic. After 5 days of bed rest, the patient was able to walk and was discharged uneventfully.
Coexistence of Optic Nerve Head Drusen and Combined Hamartoma of the Retina and Retinal Pigment Epithelium in a Taiwanese Male
Authors: Chang Yo‐Chen , Tsai Rong‐Kung
Published: April 2009

We report the case of a 38‐year‐old male patient with a 1‐year history of progressively blurred vision in his left eye. He visited our clinic and underwent a series of ophthalmologic examinations including computed tomography, fluorescein angiography and optical coherence tomography. The final diagnosis was optic nerve head drusen and combined hamartoma of the retina and retinal pigment epithelium in his left eye.
Gastric Subserosal Hematoma Developing from Focal Pancreatitis: A Case Report
Authors: Chou Chen‐Te , Chen Ran‐Chou , Yang Albert D.
Published: April 2009

Pancreatitis complicated by gastric wall hemorrhagic is rarely reported. The imaging findings of focal pancreatitis with gastric wall hemorrhage can mimic a disease entity of gastric origin. We report a case of gastric subserosal hematoma developing in a patient with focal pancreatitis. The patient was initially scheduled to receive subtotal gastrectomy due to a presumed diagnosis of a disease entity of gastric origin. Computed tomography of the abdomen revealed focal pancreatitis that had eroded the gastric wall resulting in subserosal hemorrhage. The radiologist informed the surgeon of the possibility of focal pancreatitis complicated by gastric hemorrhage. The gastric subserosal hematoma was treated with percutaneous drainage and the patient recovered uneventfully.
Predicting climate change impacts on water resources in the tropical Andes: Effects of GCM uncertainty
Authors: Buytaert Wouter , Célleri Rolando , Timbe Luis
Published: April 2009

There is a strong demand from policy makers for predictions about the potential impacts of climate change on water resources. Integrated environmental models, combining climatic and hydrologic models, are often used for this purpose. This paper examines the impact of uncertainties related to GCMs in hydrological impact studies in the tropical Andes. A conceptual hydrological model is calibrated on data from four mesoscale, mountainous catchments in south Ecuador. The model inputs are then perturbed with anomalies projected by 20 GCMs available from the IPCC Data Distribution Centre. The results show that on average, the average monthly discharge is not expected to change dramatically. However, the simulated discharges driven by different global climate model forcing data can diverge widely, with prediction ranges often surpassing current discharge.
Two‐process model for the atmospheric weathering, oxidation and ageing of diesel soot
Authors: Braun Artur
Published: April 2009

The weathering characteristic of diesel exhaust particulate (DEP) matter is spectroscopically obtained by an atmospheric study under realistic, ambient conditions. DEP subjected to weathering by exposure to ambient atmosphere (air, humidity, solar radiation, and temperature variation) for seven weeks shows systematic changes in C(1s) x‐ray absorption spectra. Quantitative analysis suggests that volatile polycyclic aromatic hydrocarbons are released from the DEP by desorption, paralleled or followed by decomposition and reaction of the amorphous part of the solid, non‐volatile carbon and potential other volatile species. The observed spectral changes are rationalized in a simple two phase model and parameterized, combining desorption of volatiles and oxidation of carbon matrix. The weathering characteristics of soot is generalized toward biomass burning products and identified as a vector quantity to be implemented for climate modelling.
Aerosol optical depth over Lauder, New Zealand
Authors: Liley J. B. , Forgan B. W.
Published: April 2009

Aerosol optical depths (AOD) measured over Lauder in Central Otago, New Zealand in 1996–1997, and continuously since 1999, are amongst the lowest observed worldwide. The Lauder measurements show a seasonal cycle in AOD with a winter minimum and summer local maximum, and there is a springtime peak that is probably due to biomass burning. The wavelength dependence of AOD suggests a relatively stable size distribution but smaller average particle size in spring. Lack of correlation with surface humidity below 90% RH, in both AOD and wavelength dependence, may constrain the likely composition of the aerosol. There was a downward but insignificant trend in mean AOD over the measurement period.
Using pedotransfer functions in vadose zone models for estimating groundwater recharge in semiarid regions
Authors: Wang Tiejun , Zlotnik Vitaly A. , Šimunek Jirka , Schaap Marcel G.
Published: April 2009

Process‐based vadose zone models are becoming common tools for evaluating spatial distributions of groundwater recharge (GR), but their applications are restricted by complicated parameterizations, especially because of the need for highly nonlinear and spatially variable soil hydraulic characteristics (SHCs). In an attempt to address the scarcity of field SHC data, pedotransfer functions (PTF) were introduced in earlier attempts to estimate SHCs. However, the accuracy of this method is rarely questioned in spite of significant uncertainties of PTF‐estimated SHCs. In this study, we investigated the applicability of coupling vadose zone models and PTFs for evaluating GR in sand and loamy sand soils in a semiarid region and also their sensitivity to lower boundary conditions. First, a data set containing measured SHCs was used in the simulations. A second data set contained correlated SHCs drawn from the covariance matrix of the first data set. The third SHC data set used was derived from a widely used PTF. Although standard deviations for individual parameters were known for this PTF, no covariance matrix was available. Hence, we assumed that the parameters of this PTF were uncorrelated, thereby potentially overestimating the volume of the parameter space. Results were summarized using histograms of GR for various sets of input parameters. Under the unit gradient flow lower boundary condition, the distributions of GR for sand and loamy sand significantly overlap. Values of GR based on mean SHCs (or GR*) generally lie off the mode of the GR distribution. This indicates that the routinely used method of taking GR* as a regional representation may not be viable. More importantly, the computed GR largely depends in a nonlinear fashion on the shape factor n in the van Genuchten model. Under the same meteorological conditions, a coarser soil with a larger n generally produces a higher GR. Therefore, the uncertainty in computed GR is largely determined by the uncertainty in estimated n by PTFs (e.g., mean and standard deviation). Under the constant head lower boundary condition, upward soil moisture flux may exist from the lower boundary. Especially for regions with shallow water tables where upward flux exists, choosing an appropriate lower boundary condition is more important than selecting SHC values for calculating GR. The results show that the distribution of GR is less scattered and GR is more intense if the constant head lower boundary is located at deeper depths.
Methods for determining soil water repellency on field‐moist samples
Authors: Dekker Louis W. , Ritsema Coen J. , Oostindie Klaas , Moore Demie , Wesseling Jan G.
Published: April 2009

In this paper we describe a simple and quick method for determining the presence of water repellency in a soil by using a small core sampler (1.5 cm in diameter, 25 cm long) and applying the water drop penetration time (WDPT) test at different depths on the sandy soil cores. Obtained results provide spatial distribution patterns of water repellency in a soil profile, demonstrating seasonal changes in repellency. An advantage of the method is that the soil is not disturbed by the sampling. For assessment of the persistence of water repellency in strongly to extremely water repellent soils, and for determination of the critical soil water contents, the WDPT test and volumetric water content determinations should preferably be performed in the laboratory.
Global warming due to increasing absorbed solar radiation
Authors: Trenberth Kevin E. , Fasullo John T.
Published: April 2009

Global climate models used in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) are examined for the top‐of‐atmosphere radiation changes as carbon dioxide and other greenhouse gases build up from 1950 to 2100. There is an increase in net radiation absorbed, but not in ways commonly assumed. While there is a large increase in the greenhouse effect from increasing greenhouse gases and water vapor (as a feedback), this is offset to a large degree by a decreasing greenhouse effect from reducing cloud cover and increasing radiative emissions from higher temperatures. Instead the main warming from an energy budget standpoint comes from increases in absorbed solar radiation that stem directly from the decreasing cloud amounts. These findings underscore the need to ascertain the credibility of the model changes, especially insofar as changes in clouds are concerned.
The hall effect in magnetic reconnection: Hybrid versus Hall‐less hybrid simulations
Authors: Malakit K. , Cassak P. A. , Shay M. A. , Drake J. F.
Published: April 2009

To understand the role of the Hall effect during fast magnetic reconnection, hybrid simulations with and without the Hall term in the generalized Ohm's Law are compared, as done originally by Karimabadi et al. (2004). It is found that reconnection with the Hall term is fast, but reconnection in the so‐called Hall‐less hybrid simulations is Sweet‐Parker like (slow) when the resistivity is constant and uniform. These results re‐affirm the importance of the Hall term in allowing fast reconnection in the hybrid model.
Laser chemistry for microstructures
Authors: Schwarzschild Bertram M.
Published: April 2009

The rapidly increasing complexity of microelectronic circuits is confronting the designers and manufacturers of integrated circuitry with new technological difficulties. By the end of the decade it may well be possible to pack a million logic gates onto a single chip. But the yield of defect-free chips falls rapidly with increasing number of components. With current lithographic techniques, the production of custom circuits in small numbers is often uneconomical, and it is widely felt that the semiconductor industry is not meeting the need for such circuits. Furthermore, these lithographic procedures cannot produce large-area integrated circuits bigger than a few square inches, and their slow turnaround time hinders the design testing necessitated by increasing miniaturization.
Hot electrons in layered semiconductors
Authors: Hess Karl , Holonyak Nick
Published: April 2009

As electronic systems—and especially computers—are used more and more widely in almost all areas of endeavor and daily life, the semiconductor technology on which they are based is being pushed to ever larger-scale integration and ever greater miniaturization. As the devices get smaller, and smaller, new problems (and maybe new opportunities) appear.1
Plasma Physics Division meets in San Diego
Authors: Jamerson Bryant
Published: April 2009

Topics will include stellarators, tokamaks, space plasmas, inertially confined fusion, mirrors and general plasma physics
21-term series yields critical indices
Authors: Lubkin Gloria B.
Published: April 2009

Discoveries in physics often hinge on a disagreement between theory and experiment of a percent or less. Because of such a discrepancy, many workers in statistical mechanics have been concerned about the complete validity of the scaling and renormalization-group theories of critical phenomena. For the three-dimensional Ising model, the experimentally derived values for the critical exponents in fluids have agreed to three significant figures with those predicted by the renormalization group. However, the predictions disagreed by a couple of percent with exponents calculated by series expansions, and the claimed accuracy of these expansion estimates was much less than a percent.
Laser selective chemistry—is it possible?
Authors: Zewail Ahmed H.
Published: April 2009

One of the main goals of chemists is to understand the “alchemy” that leads to the building and breaking of molecules. There are many different ways of approaching this goal. One of these is photochemistry, the cracking of molecules by adding energy in the form of light to break bonds in the molecules. The resulting bond breakage is in most cases limited by statistical thermodynamic laws. With sufficiently brief and intense laser radiation properly tuned to specific resonances, we hope to bypass the statistical laws and break molecules precisely where we want to break them. Intellectually this is a challenging problem; if we succeed, laser selective chemistry may also have application in various areas of pure and applied chemistry and, perhaps, in medicine.
Electromagnetic guns and launchers
Authors: Schwarzschild Bertram M.
Published: April 2009

While we accelerate elementary particles and ions by the most advanced electromagnetic means, our standard techniques for propelling macroscopic objects—from birdshot to interplanetary vehicles—are not very different from those in use since the introduction of gunpowder from China. But propulsion by chemical combustion suffers from severe limitations that are keenly felt by people interested in space travel, inertial-confinement fusion, and even such prosaic pursuits as artillery.
Neutron interferometry
Authors: Werner Samuel A.
Published: April 2009

Diffraction effects at wavelengths on the order of angstroms have been known since Max von Laue's demonstrations of x-ray diffraction in 1912. Interference between well-separated, coherent beams, however, is much more difficult to arrange.
The first fifty years of the AAPT
Authors: Phillips Melba
Published: April 2009

Fifty years ago there was no way for physics teachers to communicate with each other, no way to share either their successes or their frustrations. Teachers had no professional standing as such, and teaching itself seemed to merit little if any recognition or reward. In December 1930 the American Association of Physics Teachers was organized as “an informal association of those interested in the teaching of physics.” By the end of 1931 the Association had grown from an original 42 to more than 500. The AAPT now has more than 10 000 members and serves the entire physics community.
Underground experiments will look for proton decay
Authors: Schwarzschild Bertram M.
Published: April 2009

Although we know of no symmetry in nature that requires the conservation of baryon number, the stability of ordinary matter would appear to attest to the absolute stability of the proton. But we're soon to have a closer look. Two groups of high-energy physicists are preparing to descend into mines in Ohio and Utah, to look for proton decays with detectors several orders of magnitude more sensitive than any employed for such a search in the past.
Linear electron–positron collider
Authors: Schwarzschild Bertram M.
Published: April 2009

When the first beams begin circulating in PEP at the Stanford Linear Accelerator Center in March, both sides of the Atlantic will have storage rings producing electron–positron collisions at center-of-mass energies up to 36 GeV. If the rich history of the previous generation of e+e− colliding-beam storage rings is any guide, this new energy regime should provide an abundance of interesting physics. But PEP and its Germany cousin PETRA (at DESY, Hamburg) still fall short of the energy range 90–150 GeV that particularly intrigues particle physicists. The European high-energy community hopes to have a storage ring (LEP) of gargantuan size and price tag, capable of achieving these energies by about 1988.
Have galactic antiprotons been found in cosmic rays?
Authors: Bennett Floyd Carse
Published: April 2009

Nearly a quarter-century after the first production of antiprotons in the laboratory, a group of experimenters using a balloon-borne superconducting-magnet spectrometer believes they have detected a statistically significant number of these particles in cosmic rays entering the Earth's upper atmosphere. The observation of cosmic-ray antiprotons—believed to be secondary particles, not primordial antimatter from the Big Bang or from antistars—has confirmed theorists' predictions of the ratio of antiprotons to protons in the interstellar medium and has greatly extended the antiproton's measured lifetime. The observation is expected to furnish new information about the amount of matter traversed by the cosmic rays and the mechanism of their acceleration.
Physics manpower: present and future
Authors: Alpher Ralph A. , Fiske Milan D. , Porter Beverly Fearn
Published: April 2009

The decade of the 1970's has been a time of turmoil and transition for the support of physics and physicists, especially of young physicists just completing their graduate years. Science, the Endless Frontier, had come to have financial horizons quite close in during the late 1960's and early 1970's. A whole generation of physicists had become accustomed to automatic careers, in which demand so far exceeded supply that the greatest problem was to choose among desirable alternatives. The great expansion of higher education had created limitless opportunities in the mode most familiar to the graduate student, and academic research—perforce with some teaching—became the normal career goal.
Evidence from PETRA adds support for QCD and gluons
Authors: Lubkin Gloria B.
Published: April 2009

Over the past several years a theory of the strong interactions known as quantum chromodynamics has been developing. This theory assumes the existence of fractionally charged quarks of spin 1/2 and that the force between the quarks is carried by a gluon, a massless spin-1 quantum. Like the quark, it is widely believed that the gluon is not directly observable.
New assessments of ozone depletion
Authors: Jacobs Michael E.
Published: April 2009

A National Academy of Sciences–National Research Council panel has doubled its earlier estimate of stratospheric ozone depletion by halocarbons, though a British government report says that our present understanding of ozone depletion is limited and makes such estimates of doubtful significance. The NRC panel on stratospheric chemistry and transport, headed by Harold Schiff of York University, Toronto, concluded that continued world-wide use of halocarbons will result in ozone depletion that is calculated to reach 16.5%, half of which will occur in the next 30 years. A 1976 NRC report estimated the eventual ozone reduction at 7.5% (PHYSICS TODAY, November 1976, page 101).
Organic solids: is energy-band theory enough?
Authors: Duke Charles B. , Schein L. B.
Published: April 2009

The study of the electronic properties of organic solids is a major new frontier in solid state physics. On the practical side, organic solids provide electronic and optical materials whose properties can be tailored to suit specific applications. They also pose continuing challenges to fundamental concepts because they afford unique model systems for establishing the bounds of validity for the traditional energy-band models that have proven so successful in describing the electronic properties of inorganic metals and semiconductors.
Are molecular clouds the heaviest objects in our Galaxy?
Authors: Schwarzschild Bertram M.
Published: April 2009

As radio astronomers survey our galaxy for the millimeter wavelengths characteristic of molecular rotations at low temperature, it is becoming clear that much of the interstellar gas in the galaxy is molecular rather than atomic. Furthermore, this molecular gas, mostly H2, appears to be concentrated in giant molecular clouds, tens of parsecs across. With masses typically several hundred thousand times that of the Sun, these giant clouds appear to be the most massive objects in the galaxy.
International Tokamak Reactor design
Authors: Schwarzschild Bertram M.
Published: April 2009

The demonstration of break-even fusion power production for brief pulses is a realistic prospect for the large deuterium–tritium tokamaks scheduled for completion in the early 1980's. But they are not likely to achieve plasma ignition. Before one can begin building practical fusion reactors, it will be necessary to build at least one significantly larger experimental tokamak—one that can achieve and control an ignited plasma for minutes at a time, with fusion neutrons bombarding the walls at power levels exceeding a megawatt per square meter.
Poincaré and cosmic evolution
Authors: Brush Stephen G.
Published: April 2009

Henri Poincaré is well known today for his contributions to many areas of mathematics and his popular writings on science. His attempts to apply physical theories to the evolution of the solar system and the rest of the universe are largely forgotten, except by a few specialists. Yet the crisp lucid prose of this brilliant thinker can still help the modern reader to appreciate the worldview of nineteenth-century science, and provides a useful introduction to a fascinating historical phenomenon that I will call “the mathematician as naturalist” (see the box on page 44).
Two dimensions in pure electron systems and monolayers
Authors: Levi Barbara G.
Published: April 2009

The questions of what properties might characterize a solid in two dimensions, and by what mechanism such a solid might melt, are central aspects of current research in condensed matter. Rigorous proofs given in the 1960's showed that truly two-dimensional systems cannot have the conventional long-range order typical of three-dimensional solids. Recent theories have described the types of order that a two-dimensional solid might possess, including the existence of a nonzero shear modulus.
Langchow plans heavy-ion facility
Authors: Lubkin Gloria B.
Published: April 2009

The Institute of Modern Physics in Langchow is one of three nuclear-physics institutes in the People's Republic of China and the only one I saw during my recent visit (PHYSICS TODAY, March 1980, page 32). The Institute has ambitous plans for a new heavy-ion facility whose first phase, scheduled to operate in 1985, is expected to produce heavy ions from carbon to xenon—with 50 MeV/nucleon for low Z and 6 MeV/nucleon for high Z. The second phase would produce light ions with 100 MeV/nucleon and all ions up to uranium with 10 MeV/nucleon.
Channeling bends particle beams and generates x rays
Authors: Schwarzschild Bertram M.
Published: April 2009

As the energies of the particles they study climb toward 1012 electron volts (1 TeV), high-energy physicists find it increasingly difficult to bend their trajectories with large electromagnets. Even with superconducting coils, these magnets are limited by saturation to a few tens of kilogauss, so that a 500-GeV proton ring requires a radius of the order of a kilometer. But now, a Soviet–American collaboration at Dubna has reported observing a phenomenon that may make it possible to bend 500-GeV protons with a radius of curvature not much more than a meter.
Long-term goals for nuclear science
Authors: Schwarzschild Bertram M.
Published: April 2009

The emerging quark-gluon picture of the strong force promises nuclear physics for the first time a theoretical basis for describing the short-range interactions in nuclei. This is one of many recent advances discussed by the Nuclear Science Advisory Committee in its report entitled A Long-Range Plan for Nuclear Science. The Committee was set up two years ago by the Department of Energy and the National Science Foundation as a permanent advisory body for planning and funding in nuclear physics and related areas (see PHYSICS TODAY, February 1978, page 77).
Applications in energy, optics and electronics
Authors: Rosenberg Robert , Kuan Tung-Sheng , Hovel Harold J.
Published: April 2009

Thin films play a vital role in nearly all electronic and optical devices. They have long been familiar as antireflection coatings on window glass, video screens, camera lenses and other optical devices; these are generally films less than 100 nm thick made from a transparent (dielectric) material with a refractive index less than that of the substrate. In solar-energy conversion, similar layers of thin films are now serving as antireflection coatings on solar-energy collectors; semitransparent metal films are used in Schottky-barrier solar cells; combinations of thin films are used for photothermal devices that generate low- or high-grade heat; and thin semiconductor films on metal or glass substrates form a promising type of low-cost solar cell. In integrated circuits, of course, thin films are pervasive: metal layers form all onchip electrical connections and gate regions for field-effect transistors, to name just two examples; oxide or nitride films form insulating barriers between other films; and layers of semiconductors are integral parts of all the structures. One of the newest applications of thin-film technologies is in circuits based films made from superconductors forming, for example, Josephson junctions such as the one shown in figure 1.
Needs versus means in high-energy physics
Authors: Panofsky Wolfgang K. H.
Published: April 2009

Some physicists have recently begun to voice their expectations that the “grand synthesis” of all physics is almost within our grasp. If only we had a little more of this or that, and if only some of the remaining nagging difficulties would go away… Here, however, I would like to turn from this sublime ambition to more down-to-earth considerations. Physics remains a science based on experience. How do we acquire that experience to determine whether or not particle physics is indeed on the right track to the “grand synthesis?”
Advanced batteries for electric vehicles—a look at the future
Authors: Walsh William J.
Published: April 2009

One of the most serious energy problems faced by our nation during the remainder of this century will be shortages of liquid fuels for transportation. It may be possible to reduce the magnitude of this problem by developing smaller, more efficient vehicles, by reducing non-essential travel, by producing synthetic fuels from coal or biomass, or by exploiting oil shales or tar sands. Each of these is only a partial solution, however, and serious liquid-fuel shortages are possible even with dramatic successes in each of them.
Refrigerator cools to 50 microkelvin
Authors: Levi Barbara G.
Published: April 2009

A double-stage nuclear demagnetization refrigerator promises to allow experiments at temperatures an order of magnitude lower than previously available. The new cooling device can not only reach record low electronic temperatures of 50 microkelvins but can maintain these temperatures long enough in an apparatus large enough to cool samples within it. The apparatus was developed at the Kernforschungsanlage Jülich in West Germany. Experimenters there have cooled about 2 kg of copper to an electronic temperature of 48 microkelvins and kept it below 60 microkelvins for more than two days. At the same time, in Japan, a group from the Institute for Solid State Physics at the University of Tokyo has reported equally low temperatures with a similar method but in a much smaller device.
Does gravity change with time?
Authors: Wesson Paul S.
Published: April 2009

The Newtonian gravitational parameter G is a constant in both Newton's law of gravitation (force = −GM1M2/r122) and Einstein's general theory of relativity. However, over the last fifty years there have been numerous suggestions that G might in fact change with time. The detailed grounds for these suggestions have differed, but most variable-G theories account for gravitation on a cosmological basis. As such, they usually involve a time-dependent G: G = G(t), where t is a parameter that can, loosely speaking, be interpreted as the “age” of the Universe. A value of G that depends on time is a drastic departure from the established physics of gravitation (based on Newton's and Einstein's theories). Before looking at G-variability in detail it is therefore logical to ask first: Why should G vary?
SIS diodes for radio astronomy
Authors: Schwarzschild Bertram M.
Published: April 2009

As radioastronomers continue to push their observations to shorter wavelengths and fainter signals, their progress is impeded by a lack of sufficiently sensitive millimeter-wave receivers capable of operating at frequencies above 100 GHz. But now a spinoff from Josephson-junction fabrication technology appears to be coming to the rescue. New metallurgical and lithographic techniques developed for Josephson-effect computers are permitting the construction of superconducting diode junctions that promise to function as high-frequency photon detectors and heterodyne mixers near the theoretical limits of sensitivity.
Tokamak ready for engineering test
Authors: Schwarzschild Bertram M.
Published: April 2009

“The Panel is pleased to record its view that the taxpayers are receiving their money's worth… While the US magnetic-fusion program represents only about a third of the worldwide effort, the US has become its unquestioned leader. As a result of this progress, the US is now ready to embark on the next step…exploration of the engineering feasibility of fusion power.”
How bats detect flying insects
Authors: Neuweiler Gerhard
Published: April 2009

In the process of evolution every possible niche for survival has been exploited by some animal species. Whenever there is a biological area that produces a surplus it becomes advantageous for some species to adapt itself to make use of that surplus; many species have thus become endowed with highly specialized skills that have given them exclusive access to some hidden treasures.
Multiple quasar may indicate another gravitational lens
Authors: Lubkin Gloria B.
Published: April 2009

Early last year a pair of quasars—0957+561 A and B—was found whose spectra were almost identical. By now it is generally believed that these twin quasars are in fact a single quasar that is multiply imaged by a gravitational lens. Recent observations and model calculations suggest that this gravitational lens effect is produced primarily by the brightest member, G1, of a cluster of galaxies, with the other members collectively producing an important effect.
Voltaic cells use photosynthesis
Authors: Schwarzschild Bertram M.
Published: April 2009

Photosynthesis in green plants is a quite remarkable solar-energy storage system, which one would dearly love to mimic. But after two centuries of investigation we still have only a very incomplete picture of how plants harness photons in the visible spectrum to perform the trick of knocking out of water molecules the electrons that ultimately serve to reduce carbon dioxide to energy-rich carbohydrates.
Nuclei may exhibit supersymmetry
Authors: Levi Barbarba G.
Published: April 2009

Are there any interactions under which bosons and fermions behave similarly? Such a query lies at the heart of the current search for supersymmetry. A supersymmetry might be described somewhat more formally as the invariance of a Hamiltonian under a transformation operator that changes bosons into fermions and vice versa. Although the search is being most hotly pursued by particle and gravitational theorists, the first evidence for a supersymmetry in nature has surfaced in nuclear physics—as manifested in the energy spectra of some complex nuclei. This application of supersymmetry is largely phenomenological, but it has nonetheless intrigued the many theorists interested in the field.
Counting the atoms
Authors: Hurst G. S. , Payne M. G. , Kramer S. D. , Chen C. H.
Published: April 2009

The title of this article was inspired by a similar one used by Ernest Rutherford for an unpublished lecture note now in the University of Cambridge library. Rutherford's title was “The Counting of Atoms,” by which he could have meant the counting of individual ionized helium atoms (alpha particles), or, alternatively, he may have had in mind “decay counting” as an indirect indication that a parent atom had transmuted. With the modern pulsed laser, Rutherford's idea becomes entirely practicable, and individual atoms can now be counted by several different methods, the subject of the present article. Our group at Oak Ridge has demonstrated these methods with apparatus like that shown in figure 1.
Ultraviolet astronomy enters the eighties
Authors: Maran Stephen P. , Boggess Albert
Published: April 2009

Ultraviolet astronomy, once the province of instrumentalists, has become an accessible and necessary technique for all astronomers. In the first three years after the 1972 launch of the Copernicus satellite about 100 astronomers used its ultraviolet-spectrometer data, outnumbering by a factor of ten the core group of Princeton University scientists who superintended the instrument. In the first two years of observational programs with the most recent ultraviolet satellite, the International Ultraviolet Explorer (IUE), this involvement of non-experimenters has mushroomed, with more than 500 scientists participating.
Peking group discusses plans for 30–50-GeV accelerator
Authors: Lubkin Gloria B.
Published: April 2009

The Institute of High-Energy Physics in Peking plans to build a proton synchrotron, 30–50 GeV in energy, roughly five years from now. This summer a ten-man delegation spent three months in the US, first at Fermilab, then at Brookhaven. They came with a preliminary design in mind and hoped to improve on that design after discussions with US accelerator designers. Meanwhile other groups from the Peking Institute of High-Energy Physics are at KEK in Japan and at CERN in Geneva.
The large spectrometers
Authors: Willis William J.
Published: April 2009

The push to investigate ever smaller distances in high-energy particle experiments requires the measurement of ever smaller cross sections. As a result, increasingly large solid-angle coverage is required to attain sufficient counting rates. In most of these experiments the composite structure of hadrons is broken up at high energies, leading to very complex reactions. Such an event, with many particles emerging, usually must be observed completely, or nearly so, to yield the data necessary to perform an incisive analysis. This is another reason for a large solid angle of observation. Furthermore, it requires the ability to measure every type of particle: charged and neutral, hadronic and electromagnetic. Because the most interesting events are rare in comparison with other processes of similar appearance, as well as on an absolute scale, our ability to identify particle type turns out to be of great importance.
The High-Resolution Streamer Chamber
Authors: Sandweiss Jack
Published: April 2009

As the contents of this issue of PHYSICS TODAY illustrate, the family of particle detectors that depend on electron multiplication processes in gases is a large and important one. Although the high-pressure streamer chamber is a relatively new development, it is a direct outgrowth of one of the branches of this family tree. (The reader interested in the “genealogy,” as well as the physical and technical principles, will appreciate the excellent book by Peter Rice-Evans.)
PLT reaches high temperature in a collisionless plasma
Authors: Lubkin Gloria B.
Published: April 2009

New experimental results at the Princeton Large Torus have shown that a low-density tokamak plasma can be heated to a record-breaking temperature for tokamaks without any serious instabilities occurring. Many plasma theorists had anticipated that at higher temperatures and lower densities trapped-particle modes would limit the temperature rise in the PLT experiment, in what was considered a worst-case situation—a collisionless plasma. Because such trapped-particle instabilities have not shown up, many fusion physicists feel encouraged that a power-producing tokamak reactor need not be nearly as large as some had feared. But the full implications on reactor size are not known.
Helium atoms probe silicon surface by diffraction
Authors: von Foerster Thomas
Published: April 2009

Atomic beams are providing a new probe for determining the surface structure of semiconductor crystals. Mark J. Cardillo and Gordon E. Becker of Bell Labs have recently been able to obtain diffraction patterns of thermal–energy helium atoms from the (100) and (111) surfaces of silicon. Their results appear to be the first observation of atom diffraction from an elemental semiconductor.
Stability in the dissipative steady state
Authors: Landauer Rolf
Published: April 2009

Stability questions arise in a number of different ways. At the simplest level we can ask about the stability of a particle in a force field. It is stable if any deviations of the particle from its initial location cause it to be exposed to forces returning it back to the initial point. With time, however, “stability” has taken on a broader meaning. We find references to the stability of an orbit, of a laser's mode of oscillation, or of a set of biological populations. Harry L. Swinney and Jerry P. Gollub recently discussed the stability of liquid flow patterns in PHYSICS TODAY (August, page 41). In all of these cases there are questions about the persistence of an initial behavior pattern.
Hydrogen in metals
Authors: Westlake Donald G. , Satterthwaite Cameron B. , Weaver John H.
Published: April 2009

Research on interstitial alloys of hydrogen with metals began over a hundred years ago, but these systems had remained little more than idle curiosities until World War II. This outlook changed when hydrogen embrittlement became recognized as a serious problem in a large number of technologically important alloys and with the advent of nuclear-reactor technology, which stimulated interest in solid metal hydrides as moderators. Several studies of the thermodynamics of metal–hydrogen systems and of hydrogen diffusion in these systems followed. The discovery in 1972 that some metal hydrides exhibit superconductivity added further interest.
Metal–insulator transitions
Authors: Mott Sir Nevill
Published: April 2009

Research on metal–insulator transitions is at the moment quite fashionable. In many materials the electrical behavior changes from metallic to nonmetallic when the pressure, temperature or magnetic field is varied or (as in alloys) when the composition is varied, and the theoretical description of these processes is quite complicated. The interest of the problem lies perhaps mainly in our imperfect understanding of the nature of a metal. In the days before quantum mechanics, when I first attended undergraduate lectures on the electron theory of solids, it was taught that in metals one or more atoms from each electron were free, whereas in nonmetals they were somehow fixed to the atoms or ions or to the chemical bonds. The long mean free paths of electrons in metals extending over hundreds or thousands of atomic spacings were not understood, and neither was the absence of any large contribution from the electrons to the specific heat.
Nobel prizes: to Kapitza for low-temperature studies…
Authors: Lubkin Gloria B.
Published: April 2009

The 1978 Nobel prize in physics has been awarded in two equal parts. One half goes to Peter Leonidovich Kapitza of the Institute for Physical Problems in Moscow “for his basic inventions and discoveries in the area of low-temperature physics.” The other half is to be shared equally by Arno Penzias and Robert W. Wilson of Bell Laboratories in Holmdel “for their discovery of cosmic microwave background radiation.” (See accompanying story on this page.) The total prize this year is roughly $165 000.
…and to Penzias and Wilson for 3 K cosmic background
Authors: Lubkin Gloria B.
Published: April 2009

Arno Penzias and Robert W. Wilson of Bell Laboratories were awarded half the 1978 Nobel prize in physics for their discovery of the cosmic microwave background, which they found accidentally while attempting to measure the intensity of radio waves emitted from the halo of gas surrounding our galaxy. Their 20-foot antenna had been built in Holmdel for satellite communications with Echo and Telstar. We recently discussed the discovery with Penzias and Wilson, who explained that their antenna was more directionally sensitive than other radio telescopes of the day. The Bell Labs antenna has back lobes more than 30 dB below an isotropic response. Thus, assuming the Earth to be at 300 K, 1/1000th of its radiation intensity (or about 0.3 K) would be received by this antenna from the ground. (Temperature and intensity are linearly related at radio wavelengths.) In an ordinary radio telescope, one might receive 20–30 K from the ground.
Time, frequency and physical measurement
Authors: Hellwig Helmut , Evenson Kenneth M. , Wineland David J.
Published: April 2009

How many basic standards do we need? Standards are necessary to measurement, and for reasons of accuracy and convenience many measurements involve frequency. With atomic and molecular transitions serving as references, measurement precisions near 10−16 are possible. The duration of the second is determined by a resonance in the cesium atom, and international atomic time is the reference for all time and frequency measurements in the world. Furthermore, frequency measurements lead, via the speed of light, to the measurement of wavelengths and, via transducers, to the measurement of many other physical quantities such as temperature and pressure. As a result, time and frequency metrology is at the root of any thinking to revise or improve our system of basic standards of measurement.
Electrical conduction in metals
Authors: Allen Philip B. , Butler William H.
Published: April 2009

Fifty years ago in the Zeitschrift für Physik, two papers were published which laid the foundations for the modern quantum theory of solids. Arnold Sommerfeld quantized the theory of the electron gas, and Felix Bloch showed how this could be generalized to a realistic theory for electrons in solids. In a delightful article in PHYSICS TODAY (December 1976 page 23) Bloch has recounted the circumstances in which he came to work on the electron theory of metals in Leipzig as Heisenberg's first graduate student.
Pellet fusion with heavy-ion beams attracts attention
Authors: Rothenberg Marian S.
Published: April 2009

Heavy-ion fusion, a late entry in the inertial confinement sweepstakes, has been gaining a good deal of ground lately. Accelerator people as well as those involved in inertial confinement, have been thinking for several years that if a beam of energetic heavy ions at sufficiently high current could be delivered to a deuterium–tritium pellet in ultrashort bursts, a successful fusion implosion could occur. In particular, during the past few years Alfred Maschke of Brookhaven National Laboratory and, independently, Ronald Martin and Richard Arnold of Argonne National Laboratory did some calculations that made the prospects for using heavy ions appear to be within reason. Interest in the possibility has become more widespread: In July 1976, the US Energy Research and Development Administration (now the Department of Energy) sponsored a two-week study of heavy ions for inertial-confinement fusion, attended by about 90 people. Money for research was put in the ERDA–DOE budget, and early last spring funding and experiments began at several laboratories in the US.
Panel recommends pulsed high-flux neutron facility
Authors: Waff Craig B.
Published: April 2009

The creation of a national high-flux pulsed spallation neutron facility is one of the major recommendations of the Panel on Research Facilities and Scientific Opportunities in the Use of Low Energy Neutrons. The panel was established in early 1977 by the Solid State Sciences Committee of the Assembly of Mathematical and Physical Sciences, National Academy of Sciences-National Research Council. Gordon K. Teal, formerly chief scientist at Texas Instruments, served as chairman and Clifford G. Shull of MIT was vice-chairman.
Positrons from quasimolecular states give data on QED
Authors: Lubkin Gloria B.
Published: April 2009

With the availability of lead and uranium beams at the new heavy-ion accelerator in Darmstadt, West Germany, it has become possible to study very strongly bound quasimolecular states formed transiently by the combined charges of projectile and target nuclei during atomic collisions. In collision systems such as uranium with uranium, provided the two nuclei approach each other close enough, one is able to explore quantum-electrodynamic phenomena for the first time under conditions where the electromagnetic coupling to the nucleus is large (Zα≳1).
Polymer additives reduce fluid drag in turbulent flow
Authors: Leuchtag H. Richard
Published: April 2009

The study of turbulence in fluid dynamics has recently advanced in several new directions, and at the same time has gone a long way towards solving a problem: the uncanny efficacy of tiny amounts of polymer additives in reducing the drag between solids and liquids in turbulent flow. The phenomenon, which may well prove a boon to farmers and firefighters, has also begun to help improve our understanding of a fundamental problem in fluid dynamics, the structure and onset of turbulence. According to François Frenkiel (David W. Taylor Naval Ship Research and Development Center), the new directions include the recognition of coherent phenomena intermixed with quasistatistical effects. New visualization techniques on the one hand, and high-speed computing methods (for data analysis as well as modelling) on the other, have brightened the outlook in the field. Much of the recent work in drag reduction is summarized in a recent volume of The Physics of Fluids, containing the proceedings of a 1976 meeting.
Portable “super spring” has apparent length of 22 km
Authors: Lubkin Gloria B.
Published: April 2009

Mechanical isolation of equipment is a long-standing problem for experimenters. For example, in 1895, Sir Charles Vernon Boys was working in Oxford, determining Newton's gravitational constant. He generally worked on Sunday night between midnight and 6:00 am. According to Boys, “The daytime, of course, is out of the question, owing to the rattling traffic on the stones in St. Giles', about a quarter of a mile away.” Boys was also troubled by rail traffic, wind, and even an earthquake.
The APS in 1977: public service in an era of limited growth
Authors: Pake George E.
Published: April 2009

Some truly great figures have served as presidents of The American Physical Society. I am absolutely certain that I cannot measure up to the standards they have set, not just for the presidency of the society but also for their leadership within the science of physics and the community of physicists. Yet I would venture to guess that only my most recent predecessors found the presidency of APS as demanding of time and effort as I did, and that future presidents will encounter the same substantial demands on their energies that characterized my year. The presidency of the society has evolved into this circumstance as physics has entered a new, more complex, and a more difficult era. In this article marking the end of my term as APS president, after reporting on the activities of the society during the past twelve months I will offer some reflections on the characteristics, the differences and the challenges that this new era in physics presents.