bluuebunny/crossref_metadata_2025 huggingface dataset:
Essay: On ‘Special Dangers’ of Perestroika to Soviet Jews, Science and Society
Authors: Goldanskii Vitalii I.
Published: January 2008

Supporters of Mikhail S. Gorbachev's perestroika and increasingly alarmed by the possibility that this program of economic restructuring and reforms may collapse. Should this occur—and it cannot be ruled out, even in the near future—it would be a disaster not only for the Soviet Union but for all humankind.
Models of String Theory and 2-D Quantum Gravity are Solved Exactly
Authors: Khurana Anil
Published: January 2008

In how many ways may a quadrilateral be dissected into a given number of smaller quadrilaterals? Or a hexagon into triangles? Or, for that matter, any polygon into given numbers of other polygons? Such questions about enumeration of dissections of a planar surface attracted the attention of mathematicians—most notably, of Leonhard Euler—in the middle of the 18th century. Mathematicians solved many cases of such problems using methods of graph theory in the 1960s. In 1978, however, physicists, in their attempts to enumerate Feynman diagrams in certain theories, independently developed a rather elegant and general method that can be used to enumerate dissections of any surface. Physical insights into the divergences in the solutions obtained by those general methods have now led to exact solutions—the first nontrivial exact solutions to date—of simple models of quantum gravity in two dimensions and of simple string theories. String theorists hope that the solutions will provide much-needed insights into the structure of those theories, just as solving the Schrödinger equation for simple, one-dimensional potentials yields insights into quantum dynamics: For example, the solutions for one-dimensional potentials show features, such as the existence of the zero-point energy and the possibility of tunneling, that distinguish quantum mechanical behavior from the classical one. In the absence of any exact solutions, attempts to understand the content of string theories had been limited to perturbation expansions in the string coupling constant. The new, exact solutions show that string theories have features, not fully understood yet, that no perturbation expansion in the coupling constant could unravel.
STM Unravels the Vortex Core in Type II Superconductors
Authors: Khurana Anil
Published: January 2008

When two conductors are brought so close together that wavefunctions of electrons in them begin to overlap appreciably, electrons in one of the conductors may tunnel into the other. The magnitude of this tunneling current depends, if the current flows, say, from a probe tip to a surface to be probed, primarily on the probability that electron states having energy and momentum similar to those of electrons in the tip exist and are unoccupied in the surface to be probed. The scanning tunneling microscope, in which a metal probe scans a surface and the tunneling current at various positions is measured, therefore yields information about the nature and density of electron states on the scanned surface. STM studies of a clean surface of 2HNbSe2 when it is superconducting have now revealed new and unexpected features in the spectrum of electron states in magnetic flux lines in superconductors. The remarkable spatial resolution of the STM, which has steadily yielded new and interesting results about physics at surfaces since the instrument was invented, once again underlies the new discoveries: Without the STM it might not have been possible to probe electronic states on the scale of a few angstroms.
Antiprotons Cooled to 4 K and Weighed in a Penning Trap
Authors: Schwarzschild Bertram
Published: January 2008

Any Lorentz-invariant local field theory must obey the CPT theorem. That is to say, the theory must be invariant under the combined operations of charge conjugation, parity inversion and time reversal, even though we know that these symmetries, taken one at a time, can be violated in elementary-particle processes. It follows that particles and their antiparticles must have identical masses and equal magnetic moments (of opposite sign).
COBE Photographs the Milky Way in Infrared
Authors: Schwarzschild Bertram
Published: January 2008

Would you believe that this is our own Milky Way? It is not an artist's conception of what the Galaxy might look like to an outside observer, but rather a near-infrared image of the inner reaches of the Milky Way, produced by the diffuse Infrared Background Experiment aboard the Cosmic Background Explorer satellite. COBE has been in Earth orbit since November. (See PHYSICS TODAY, March, page 17.)
Solar Neutrino Update: Three Detectors Tell Three Stories
Authors: Schwarzschild Bertram
Published: January 2008

For 17 years, a 600-ton vat of cleaning fluid in the bowels of a South Dakota gold mine was the only detector on Earth looking at neutrinos from the Sun. And what Raymond Davis and his colleagues at the Homestake gold mine reported year after year was very puzzling: Their long-term average capture rate from 1970 through 1985 was 0.472±0.037 solar neutrinos captured per day. But the “standard solar model” predicted, with considerable confidence, that the Homestake detector ought to be seeing about 1.8 neutrinos from the Sun per day. Allowing for the uncertainties of the standard solar model, 1.2 captures per day was the very least the theorists would find comprehensible in the light of what they thought they knew about how the Sun works.
Hubble Investigation Board Finds Out What Went Wrong
Authors: Schwarzschild Bertram
Published: January 2008

By what sequence of mishaps did the Hubble Space Telescope acquire its unfortunate spherical aberration? And how did this severe optical flaw escape notice until after the HST was launched into orbit last spring? These were the two principal questions set out for the HST Optical Systems Board of Investigation convened by NASA at the end of June, shortly after it became clear that the Hubble telescope was hobbled by half a wavelength of spherical aberration. (See PHYSICS TODAY, August, page 17.)
Special Issue: Communicating Physics to the Public
Authors: Levi Barbara Goss , Schmidt Jeffrey
Published: January 2008

How does the layman learn about physics? Formal education is not the only way, and it probably is not even the main way. Long after the blackboards have become a chalky memory, people are scanning newspaper headlines, looking through weekly newsmagazines, listening to the radio while commuting, sampling programs on television after work or visiting museums while on vacation. And from each of these they get messages about science: Newspapers feature exciting news such as the detection of supernova 1987A; science “experts” on TV debate nuclear power and global warming; magazines and books tempt us with unsolved mysteries or regale us with the adventures of curious characters.
A channel Brownian pump powered by an unbiased external force
Authors: Ai Bao-quan , Liu Liang-gang
Published: January 2008

A Brownian pump of particles in an asymmetric finite tube is investigated in the presence of an unbiased external force. The pumping system is bounded by two particle reservoirs. It is found that the particles can be pumped through the tube from a reservoir at low concentration to one at the same or higher concentration. There exists an optimized value of temperature (or the amplitude of the external force) at which the pumping capacity takes its maximum value. The pumping capacity decreases with increasing radius at the bottleneck of the tube.
Physics Nobel Prize Awarded for Microscopies Old and New
Authors: Schwarzschild Bertram
Published: January 2008

The 1986 Nobel Prize in Physics has been awarded for two profound advances in the history of microscopy, separated by half a century. Both involve imaging with electrons to achieve resolutions far beyond the capability of optical microscopy. But there the resemblance ends.
Tristan e+e− Collider in Japan Yields 50 GeV of Mass
Authors: Lubkin Gloria B.
Published: January 2008

Tristan, an electron-positron collider at KEK, the National Laboratory for High Energy Physics at Tsukuba, Japan, achieved collisions with 25 GeV in each beam in mid-November. At that time the maximum luminosity was 2.6×1029/cm2 sec. This center-of-mass energy of 50 GeV makes Tristan the world record holder for electron-positron collisions, at least until the SLAC Linear Collider starts colliding-beam trials, scheduled to begin next month. SLC will have 50 GeV in each beam.
Field response and switching times in biaxial nematics
Authors: Berardi Roberto , Muccioli Luca , Zannoni Claudio
Published: January 2008

We study by means of virtual molecular dynamics computer experiments the response of a bulk biaxial nematic to an applied external field and, in particular, the relative speed of reorientation of the principal director axis and of the secondary one, typical of these new materials, upon a π∕2 field switch. We perform the simulations setting up and integrating the equations of motion for biaxial Gay-Berne particles using quaternions and a suitable time reversible symplectic integrator. We find that switching of the secondary axis is up to an order of magnitude faster than that of the principal axis, and that under fields above a certain strength a reorganization of local domains, temporarily disrupting the nematic and biaxial ordering, rather than a collective concerted reorientation occurs.
One-dimensional model for water and aqueous solutions. I. Pure liquid water
Authors: Ben-Naim Arieh
Published: January 2008

Two simplified one-dimensional models for waterlike particles are studied. One is referred to as the primitive model which is a simplified version of a model introduced by Ben-Naim in 1992 [Statistical Thermodynamics for Chemists and Biochemists (Plenum, New York, 1992)]. The second, referred to as the primitive cluster model, is a simplified version of the model used by Lovett and Ben-Naim in 1969 [J. Chem. Phys. 51, 3108 (1969)]. The two models are shown to be nearly equivalent and both exhibit some of the most characteristic behavior of liquid water. It is argued that a key feature of the molecular interactions—the correlation between the strong binding energy and low local density—is essential for the manifestation of the anomalous behavior of liquid water. It is also essential for the understanding of the outstanding behavior of liquid water.
One-dimensional model for water and aqueous solutions. II. Solvation of inert solutes in water
Authors: Ben-Naim Arieh
Published: January 2008

The two one-dimensional models introduced in Part I are used to study the thermodynamics of solvation of inert solutes in water. It is shown that the anomalously large Gibbs energy of solvation of inert solutes in water, on one hand, and the large negative entropy of solvation, on the other hand, arise from different molecular sources. While the primitive model can give rise to a large positive solvation Gibbs energy, it fails to show large negative entropy and enthalpy of solvation. It is remarkable that the primitive cluster model can show both the large positive Gibbs energy and enthalpy of solvation.
Mode selective photodissociation dynamics in V+(OCO)
Authors: Citir Murat , Metz Ricardo B.
Published: January 2008

The electrostatic V+(OCO) complex has a vibrationally resolved photodissociation spectrum in the visible. Photodissociation produces V++CO2 (nonreactive pathway) and VO++CO (reactive pathway). Production of VO+ is energetically favored, but spin forbidden. One-photon dissociation studies confirm mode selectivity observed by Lessen et al. [J. Chem. Phys. 95, 1414 (1991)]: excitation of one quantum of rocking motion enhances VO+ production by >30%. Branching ratio measurements in one-photon dissociation are extended to higher energy. The effect of OCO antisymmetric stretch vibrations on reactivity is investigated using vibrationally mediated photodissociation, in which the OCO antisymmetric stretch is excited at 2390.9cm−1. Vibrationally excited molecules are then dissociated in the visible. Seven vibronic bands are investigated, involving the antisymmetric stretch alone and in combination with the CO2 bend, the V+(OCO) stretch and rock. Exciting the antisymmetric stretch leads to a ∼15% increase in the reactive VO+ channel, compared to other states at similar energy. Combination bands involving the antisymmetric stretch all show slightly higher reactivity. Electronic structure calculations were performed to characterize the dissociation pathways and excited electronic states of V+(OCO). The geometries of reactants, products, and transition states and relative energies of quintet and triplet states were determined using hybrid density functional theory; energies were also calculated using the coupled cluster with single, double and perturbative triple excitations method. In addition, time-dependent density functional theory calculations were performed to predict the excited electronic states of quintet and triplet V+(OCO). Spin-orbit coupling of quintet states to triplet states was calculated and used to compute intersystem crossing rates, which reproduce many of the observed mode selective trends. The V+–OCO stretch and OCO antisymmetric stretch appear to enhance reactivity by increasing the intersystem crossing rate.
Comment on “Model of saturated lithium ammonia as a single-component liquid metal” [J. Chem. Phys. 124, 074702 (2006)]
Authors: Chuev Gennady N. , Quémerais Pascal
Published: January 2008

We demonstrate in this Comment that the theory of simple metals applied to the saturated Li–NH3 solution in the titled paper [U. Pinsook and S. Hannongbua, J. Chem. Phys.124, 074702 (2006)] should account for the peculiarities of the solution, namely, the high solvent polarizability and different energy scales for ion-ion and electron-electron interactions. Calculations not taking into account these peculiarities contradict the experimental phase diagram of the Li–NH3 solution.
Special Issue: Helium-3 and Helium-4
Authors: Donnelly Russell J.
Published: January 2008

Low-temperature physics has traditionally been associated with the subjects of superconductivity and liquid and solid helium. While a glance at the program of any current meeting will reveal many other fascinating activities under the rubric of low-temperature physics, these two subjects have continued to be pursued with vigor and striking success for three quarters of a century. Readers of PHYSICS TODAY were given a view of modern research on superconductivity in the March 1986 issue. This special issue is devoted to modern investigations in He3 and He4.
Still More Squeezing of Optical Noise
Authors: Levi Barbara Goss
Published: January 2008

Quantum optics experimenters have been pushing hard to generate greater “squeezing.” This drive was encouraged by last year's milestone demonstration at AT&T Bell Labs that the noise from an optical cavity had been measurably squeezed, that is, that the noise in one phase of the signal had been reduced below the level normally associated with quantum mechanical fluctuations in the vacuum field. Until then, that vacuum noise level had represented the fundamental quantum limit to precision in optical experiments. The Bell Labs experiment reduced the noise by 7–10% below this normal quantum limit (see PHYSICS TODAY, March 1986, page 17), and several experiments since then have achieved noise reductions of at least 20%. The most spectacular results to date have been obtained by a team at the University of Texas at Austin consisting of Ling-An Wu, Min Xiao, H. Jeffrey Kimble, John L. Hall (of the Joint Institute for Laboratory Astrophysics) and Huifa Wu, who have observed noise reductions to more than 60% below the normal level.
APS Releases Report on Directed-Energy Weapons
Authors: Lubkin Gloria B.
Published: January 2008

During the APS spring meeting in Crystal City, Virginia, late last month, the APS Council released the long-awaited report of the Study Group on the Science and Technology of Directed Energy Weapons. APS Executive Secretary William W. Havens Jr remarked, “It may be the most important APS study ever done.”
Probing Cosmic Geometry Suggests the Universe is Flat
Authors: Schwarzschild Bertram
Published: January 2008

The tug of gravity is gradually slowing down the general Hubble expansion of the cosmos. We don't, however, have a good observational fix on the rate of this universal deceleration. In particular, we don't know whether we're slowing to an ultimate halt, to be followed by a recontraction to a “Big Crunch,” or whether the Hubble expansion will go on forever.
Astronomers Seek High Resolution
Authors: Andersen Per H.
Published: January 2008

Astronomical advances often depend upon technological advances. In recent years charge-coupled-device detectors on existing telescopes have reached photon efficiencies approaching 100%, significantly better than those of photographic detectors. (See PHYSICS TODAY, March, page 19.) “The 5-meter Hale telescope with a charge-coupled-device detector is equivalent to a 50-meter diameter telescope equipped with 1948 photographic plates,” says Peter Waddell (University of Strathclyde, Glasgow), who is trying to develop large membrane mirrors that may eventually be used in space. “Detectro sensitity cannot go much further, which is why astronomers are looking once again for larger telescopes.”
Will Future Astronomers Observe with Liquid Mirrors?
Authors: Andersen Per H.
Published: January 2008

Experiments with liquid-mirror prototypes go back at least to the early 1800s. Isaac Newton, who invented the reflecting telescope and certainly thought about spinning liquids, may be the originator of the concept. In 1908 Robert Wood (Johns Hopkins University) made a 0.5-m liquid-mirror telescope. Vulnerable to jarring motions, Wood's mirror could detect “the footsteps of a person running 50 yards from the telescope house.” The problems were serious: Variable motor speed caused distorting ripples on the fluid surface and such a transit telescope is unable to point in any direction other than the zenith, that is, straight up. Hence a liquid-mirror telescope would seem impractical.
Even Lanthanum Copper Oxide is Superconducting
Authors: Khurana Anil
Published: January 2008

The current excitement in superconductivity started with the discovery last year that lanthanum copper oxide when suitably doped with barium or strontium is a superconductor at temperatures up to 40 K. Now, researchers from France, IBM San Jose and Yorktown Heights and Bell Communications Research report that even the undoped lanthanum copper oxide is a superconductor with critical temperature up to 40 K. On the other hand, researchers at Exxon Research and Engineering Company have obtained definitive evidence for a transition to an antiferromagnetic phase in this compound (see figure, this page). Whether the low-temperature phase of lanthanum copper oxide is antiferromagnetic or superconducting, researchers believe, depends very sensitively on lanthanum and oxygen concentrations.
Experiment Challenges Theory in Positronium Measurements
Authors: Levi Barbara G.
Published: January 2008

Positronium—the bound state of an electron and positron—appears to decay more rapidly than calculations based on quantum electrodynamics predict. Four experiments over the last ten years have measured decay rates for positronium's triplet ground state that were higher than current theoretical estimates, but never by more than a few standard deviations. In a recent experiment with four times greater precision, Chris Westbrook, David Gidley, Ralph Conti and Arthur Rich at the University of Michigan determined a decay rate that is ten standard deviations higher than the theory predicts. They reported a value of 7.0516±0.0013 per second, compared with the theoretical prediction of 7.03830±0.00007 per second. Numerical integration contributes an uncertainty in the fifth decimal place of the prediction.
Large-Scale Structure, Steaming and Galaxy Formation
Authors: Andersen Per H.
Published: January 2008

“Observational results indicating large-scale streaming motions in the universe might be real giant-killers of theories,” says theorist Richard Bond (Canadian Institute for Theoretical Astrophysics). (See news story on page 17.) Models based on the inflationary paradigm (see Andrei Linde's article in PHYSICS TODAY, September, page 61) are severely strained by the recent observations, Bond told us: “If true, the large-scale streaming puts in jeopardy the assumed initial spectrum of density fluctuations coming out of inflation. But the microwave background is, I think, ultimately the best probe of fluctuations and structure.”
Effects of end group functionalization and level alignment on electron transport in molecular devices
Authors: Kim Gunn , Wang Shuchun , Lu Wenchang , Buongiorno Nardelli Marco , Bernholc J.
Published: January 2008

The effect of metal-molecule coupling on electron transport is examined in the prototypical case of alkane chains sandwiched between gold contacts and bridged by either amine or thiol groups. The results show that end group functionalization plays a crucial role in controlling electron transport, and that the symmetries and spatial extent of orbitals near the Fermi level control the conductivity rather than the strength of the bonding. For amine/Au and thiol/Au junctions, a crossover in conductivity with increasing bias is predicted.
Toward accurate barriers for enzymatic reactions: QM/MM case study on p-hydroxybenzoate hydroxylase
Authors: Mata Ricardo A. , Werner Hans-Joachim , Thiel Stephan , Thiel Walter
Published: January 2008

The hydroxylation reaction catalyzed by p-hydroxybenzoate hydroxylase has been investigated by quantum mechanical/molecular mechanical (QM/MM) calculations at different levels of QM theory. The solvated enzyme was modeled (∼23000 atoms in total, 49 QM atoms). The geometries of reactant and transition state were optimized for ten representative pathways using semiempirical (AM1) and density functional (B3LYP) methods as QM components. Single-point calculations at B3LYP/MM optimized geometries were performed with local correlation methods [LMP2, LCCSD(T0)] and augmented triple-zeta basis sets. A careful validation of the latter approach with regard to all computational parameters indicates convergence of the QM contribution to the computed barriers to within ∼1kcalmol−1. Comparison with the available experimental data supports this assessment.
Turbulence suppression in channel flows by small amplitude transverse wall oscillations
Authors: Jovanović Mihailo R.
Published: January 2008

We model and analyze the influence of small amplitude transverse wall oscillations on the evolution of velocity perturbations in channel flows. We quantify the effect of stochastic outside disturbances on velocity perturbation energy and develop a framework for the optimal selection of transverse oscillation parameters for turbulence suppression. A perturbation analysis is used to demonstrate that depending on the wall oscillation frequency the energy of velocity perturbations can be increased or decreased compared to the uncontrolled flow. Our results elucidate the capability of properly designed oscillations to reduce receptivity of the linearized Navier-Stokes equations to stochastic disturbances, which entails decreased levels of variance in wall-bounded shear flows.
Simulation of dynamics-coupling in piezoelectric tube scanners by reduced order finite element analysis
Authors: Maess Johannes , Fleming Andrew J. , Allgöwer Frank
Published: January 2008

Piezoelectric tube scanners are widely used in scanning probe microscopes to position the sample or the probe. Fast and accurate scanning requires the suppression of dominant low-frequency resonances as well as the compensation of dynamics-coupling effects. The present article gives a detailed description of the fully coupled tube scanner dynamics over a wide frequency range modeled by finite element (FE) analysis using the commercially available software package ANSYS. The effect of a sample mass attached to the top of the tube is investigated by considering its added mass and local stiffening. A model order reduction scheme is applied to obtain a low order model that describes the lateral and vertical deflections as well as the voltage induced on quadrant electrodes. Comparison to experimental data demonstrates a good agreement for both the full FE model and reduced order model.
Process-induced positive charges in Hf-based gate stacks
Authors: Zhao C. Z. , Zhang J. F. , Chang M. H. , Peaker A. R. , Hall S. , Groeseneken G. , Pantisano L. , De Gendt S. , Heyns M.
Published: January 2008

Hf-based gate stacks will replace SiON as a gate dielectric even though our understanding of them is incomplete. For an unoptimized SiO2 layer, an exposure to H2 at a temperature over 450 °C can lead to positive charging. In this work, we will show that a thermal exposure of Hf-based gate stacks to H2 can also induce a large amount of positive charge (∼1013 cm−2). There is little information available on this process-induced positive charge (PIPC) and the objective of this work is to fill this knowledge gap. The work is divided into two parts: an investigation of the features and properties of PIPC, followed by an exploration of its dependence on process conditions. It will be shown that PIPC does not originate from the generation of interface states, is stable both thermally and electrically, and has a large sample-to-sample variation. It consists of two components: fixed and mobile. Regarding its dependence on process conditions, PIPC occurs in both HfO2 and Hf-silicate stacks, in devices with either TaN or poly-Si gates, and in both p metal-oxide-semiconductor field-effect transistors (pMOSFETs) and nMOSFETs. PIPC is generally enhanced by nitridation, although it can also be observed in some Hf-based gate stacks without nitridation.
Force approximation for a plasma actuator operating in atmospheric air
Authors: Singh Kunwar Pal , Roy Subrata
Published: January 2008

A plasma actuator has been studied using a self-consistent multibody system of quiescent air, plasma, and dielectric. Equations governing the motion of charged and neutral species have been solved with Poisson’s equation. Based on first principles analysis, a functional relationship between electrodynamic force and electrical and physical control parameters has been approximated and numerically tested for air. The magnitude of approximated force increases with the fourth power of the amplitude of rf potential. Thus, the induced fluid velocity also increases. The induced velocity shows momentum injection very close to the actuator surface. There is, however, a very small increase in the induced velocity with the forcing frequency. For the specific range of operational parameters considered, the proposed force relation may help speed up the plasma actuator design process.
Fast and slow dynamics in Pr60Ni10Cu20Al10 melts as seen by neutron scattering
Authors: Chathoth S. M. , Podlesnyak A.
Published: January 2008

We present experimental results on the fast β and slow α relaxational dynamics observed through incoherent quasielastic neutron scattering from Pr60Ni10Cu20Al10 melts. The density correlation function, measured over a range of temperatures, shows a clear two-step relaxation process. The critical or crossover temperature, Tc, evaluated from the asymptotic scaling function of the mode-coupling theory was found to be at 620±5 K. The correlation decay is not exponential, being extended over a far wider time range. In addition, the stretched exponent βq was found to be independent of temperature and momentum transfer (q). The self-diffusivity is an order lower compared with that observed in simple metallic liquids at their melting temperature.
Structures and properties of La- and Sm-doped BaTiO3 sputtered films: Post-annealing and dopant effects
Authors: Wu C. H. , Chu J. P. , Chang W. Z. , John V. S. , Wang S. F. , Lin C. H.
Published: January 2008

200 - nm -thick La- and Sm-doped BaTiO3 thin films with A∕B ratio of unity fabricated by magnetron sputtering on the Pt∕Ti∕SiO2∕Si substrate have been characterized. The effects of post-annealing and the amount of dopant on structure and electrical properties were studied. X-ray diffraction studies reveal that the films annealed at 750°C show tetragonal BaTiO3 crystal structure without any detectable second phase formation. X-ray photoelectron spectroscopy results confirm that La substitutes the A site and Sm is in the B site in lightly doped films. La2O3 or Sm2O3 is present in the BaTiO3 structure when the dopant content is more than 1.4at.% La or 1.0% Sm. The permittivity increases with increasing annealing temperature up to 750°C due to the coarse grains and better crystallinity. The leakage current property is found to vary with the type of dopant.
A compact strip-line pulsed power generator for isentropic compression experiments
Authors: Ao T. , Asay J. R. , Chantrenne S. , Baer M. R. , Hall C. A.
Published: January 2008

Veloce is a medium-voltage, high-current, compact pulsed power generator developed for isentropic and shock compression experiments. Because of its increased availability and ease of operation, Veloce is well suited for studying isentropic compression experiments (ICE) in much greater detail than previously allowed with larger pulsed power machines such as the Z accelerator. Since the compact pulsed power technology used for dynamic material experiments has not been previously used, it is necessary to examine several key issues to ensure that accurate results are obtained. In the present experiments, issues such as panel and sample preparation, uniformity of loading, and edge effects were extensively examined. In addition, magnetohydrodynamic simulations using the ALEGRA code were performed to interpret the experimental results and to design improved sample/panel configurations. Examples of recent ICE studies on aluminum are presented.
Quasi-guided electromagnetic beam propagation in one-dimensional photonic crystal with a left-handed metamaterial
Authors: Zharov Alexander A. , Zharova Nina A.
Published: January 2008

We show that due to consecutive phase front conjugation in one-dimensional photonic crystals consisting of layers of conventional right-handed dielectrics and left-handed metamaterials with simultaneously negative dielectric permittivity and magnetic permeability, the wide two-dimensional electromagnetic beams can exhibit quasi-guided propagation completely restoring its initial transverse structure over each period of photonic crystal. We find the conditions of quasi-guided beam propagation for both transverse electric and transverse magnetic polarization and corresponding dispersion relations for such a waveguide. We also demonstrate that waveguide modes can be forward as well as backward at different values of permittivity and permeability of the left-handed layers.
Enhancement of Si–O hybridization in low-temperature grown ultraviolet photo-oxidized SiO2 film observed by x-ray absorption and photoemission spectroscopy
Authors: Tsai H. M. , Ray S. C. , Pao C. W. , Chiou J. W. , Huang C. L. , Du C. H. , Pong W. F. , Tsai M.-H. , Fukano A. , Oyanagi H.
Published: January 2008

The dielectric properties associated with the electronic and bonding structures of SiO2 films were examined using the Si L3,2- and O K-edge x-ray absorption near-edge structures (XANES) and valence-band photoemission spectroscopy (VB-PES) techniques. The Si L3,2- and O K-edge XANES measurements for the low-temperature grown UV-photon oxidized SiO2 (UV-SiO2) and the conventional high-temperature thermal-oxidized SiO2 (TH-SiO2) suggest enhancement of O 2p–Si 3p hybridization in UV-SiO2. VB-PES measurements reveal enhancement of nonbonding O 2p and O 2p–Si 3p hybridized states. The enhanced O 2p and Si 3p hybridization implies a shortening of the average Si–O bond length, which explains an increase of the density and the improvement of the dielectric property of UV-SiO2.
Mass and Auger electron spectroscopy studies of the interactions of atomic and molecular chlorine on a plasma reactor wall
Authors: Guha Joydeep , Donnelly Vincent M. , Pu Yi-Kang
Published: January 2008

We have investigated the interactions of Cl and Cl2 with an anodized Al surface in an inductively coupled chlorine plasma. The cylindrical substrate is rapidly rotated within a differentially pumped wall and is exposed to the plasma 35% of the time through a conical skimmer. On the opposite side of the substrate, a second skimmer and differential pumping allows the surface and desorbing products to be analyzed by Auger electron spectroscopy (AES), line-of-sight mass spectrometry (MS), and through pressure rise measurements. In a 600W Cl2 plasma at 5mTorr, the surface becomes covered with a layer with the overall stoichiometry of about Al2Si2O10Cl3, with Si being the result of the slow erosion of the quartz discharge tube. The surface layer composition (specifically Cl coverage) does not change as a function of the delay time (1ms–10min) between plasma exposure and AES characterization. In contrast to AES measurements, the MS signals from Cl2 desorption, resulting from recombination of Cl atoms, decrease by about a factor of 10 over the 1–38ms probed by varying the substrate rotation frequency. Substantial adsorption and desorption of Cl2 are also observed with the plasma off. Cl recombination coefficients (γCl) derived from an analysis of the time-dependent MS signals range from 0.01 to 0.1 and increase with increasing Cl-to-Cl2 number density ratio, suggesting a competition for adsorption sites between Cl2 and Cl.
Infrared surface plasmon resonance technique for biological studies
Authors: Lirtsman V. , Golosovsky M. , Davidov D.
Published: January 2008

We report on a surface plasmon resonance (SPR) technique based on Fourier-transform infrared spectrometer. In contrast to the conventional surface plasmon technique, operating at a fixed wavelength and at variable angle of incidence, our setup allows the wavelength and the angle of incidence to be varied simultaneously. We explored the potential of the SPR technique in the infrared for biological studies involving aqueous solutions. Using computer simulations, we found the optimal combination of parameters (incident angle and wavelength) for performing this task. Our experiments with physiologically important glucose concentrations in water and in human plasma verified our computer simulations. Importantly, we demonstrated that the sensitivity of the SPR technique in the infrared range is not lower and, in fact, is even higher than that for visible light. We emphasize the advantages of infrared SPR for studying glucose and other biological molecules in living cells.
Novel miniature electrostatic generator
Authors: Bakhoum Ezzat G.
Published: January 2008

A new and unusual design for an electrostatic high voltage generator is introduced. The prototype device built by the author can generate a voltage up to approximately 180kV; yet, its physical size is only a fraction of the size of a comparable Van de Graaff generator. In recent years there has been increasing demand for high voltage generators that are also very compact and lightweight. The new design introduced here fulfills that requirement.
A micromachined surface stress sensor with electronic readout
Authors: Carlen Edwin T. , Weinberg Marc S. , Zapata Angela M. , Borenstein Jeffrey T.
Published: January 2008

A micromachined surface stress sensor has been fabricated and integrated off chip with a low-noise, differential capacitance, electronic readout circuit. The differential capacitance signal is modulated with a high frequency carrier signal, and the output signal is synchronously demodulated and filtered resulting in a dc output voltage proportional to the change in differential surface stress. The differential surface stress change of the Au(111) coated silicon sensors due to chemisorbed alkanethiols is Δσs≈−0.42±0.0028Nm−1 for 1-dodecanethiol (DT) and Δσs≈−0.14±0.0028Nm−1 for 1-butanethiol (BT). The estimated measurement resolution (1Hz bandwidth) is ≈0.12mNm−1 (DT: 0.2pgmm−2 and BT: 0.8pgmm−2) and as high as ≈3.82μNm−1 (DT: 8fgmm−2 and BT: 24fgmm−2) with system optimization.
Formation of an ordered pattern of Bi nanolines on InAs(100) by self-assembly
Authors: Ahola-Tuomi M. , Laukkanen P. , Punkkinen M. P. J. , Perälä R. E. , Väyrynen I. J. , Kuzmin M. , Schulte K. , Pessa M.
Published: January 2008

Self-assembly of uniform patterns of nanolines over large surface areas has been proven to be difficult. The authors report that bismuth (Bi) adsorbate self-assembles into an ordered pattern of Bi nanolines separated by 4.3nm on the Bi-stabilized InAs(100)(2×1). The resulted nanoline surface is studied by scanning tunneling microscopy (STM) and low-energy electron diffraction. The plausible atomic models for the Bi nanolines are proposed on the basis of the STM results. The Bi lines are suggested to consist of two chains of adjacent Bi dimers positioned parallel to the chain and parallel to the Bi dimers of the (2×1) substrate.
Room-temperature highly anisotropic ferromagnetism and uniaxial spin amplification in (In,Mn)As quantum dots
Authors: Zhang X. W. , Fan W. J. , Li S. S. , Xia J. B.
Published: January 2008

The hole-mediated ferromagnetism in (In,Mn)As quantum dots is investigated using the k⋅p method and the mean field model. It is found that the (In,Mn)As quantum dot can be ferromagnetic at room temperature when there is one hole in the dot. For the spherical quantum dots, the Curie temperature decreases as the diameter increases, and increases as the effective composition of magnetic ions increases. It is interesting to find that the (In,Mn)As oblate quantum dot has highly anisotropic Zeeman splitting and ferromagnetism due to the spin-orbit coupling effect, which can be used as an uniaxial spin amplifier.
Michelson in 1887
Authors: Moyer Albert E.
Published: January 2008

In July 1907, Bernhard Hasselberg, a member of the Nobel Prize committee, confided to George Ellery Hale that Albert Michelson was his choice for the year's physics award: “In my opinion he is in every way, and absolutely without comparison, the most meritorious of all the gentlemen now proposed to us.”1 After the Swedish committee chose Michelson, making him the first American ever picked for a Nobel science prize, Hasselberg was even more complimentary. He wrote to Hale that Michelson's selection “is the best of all which have been made up to this date. Our earlier laureates Röntgen, Lorentz, Zeeman, Becquerel, Curie, Rayleigh, Lenard and J. J. Thomson are indeed men of eminent scientific merits, but for my part I consider the work of Michelson as more fundamental and also by far more delicate.” Even if we allow for the idiosyncrasies of the Nobel selection process and for Hasselberg's personal biases, we still must grant that by 1907 Michelson had earned the respect of the international physics community.
Arthur Gordon Webster, Founder of the APS
Authors: Phillips Melba
Published: January 2008

Fewer than one in a hundred present members of The American Physical Society could name its founder. Carl Barus, head of physics at Brown University for many years and a member of the committee Arthur Gordon Webster organized in 1899 to discuss the possibility of forming a physical society, wrote many years after that meeting, “The foresight and chief credit…must be assigned to the tireless activity of Prof. Webster and it is to be hoped that the Physical Society may some day commemorate the event in his honor.” According to Ernest Merritt, who was the first secretary of the society and later became its president, “All of us who remember those days are agreed that Webster thoroughly deserved the title that was often given him—‘father of The American Physical Society.’”
Mass Extinctions Caused by Large Bolide Impacts
Authors: Alvarez Luis W.
Published: January 2008

A wealth of evidence has forced my colleagues and me to conclude that 65 million years ago a mountain-sized object hit Earth and caused the extinction of most of the then existing species, bringing a close to the Cretaceous period of geological history and opening the Tertiary period. Much of the evidence for this lies in the unusual layer of clay that separates those periods in the geological record, shown in figure 1. For example, this stratum contains anomalously high concentrations of iridium, an element whose abundance in the crust of the Earth is only one ten-thousandth that in meteorites and, presumably, in other “bolides,” or large pieces of Solar System debris.
Bang: The Supernova of 1987
Authors: Helfand David
Published: January 2008

February was a great month for physics. The subject of high-Tc Superconductors exploded as labs around the world pushed the transition temperature for a variety of compounds above 77 K. The Reagan Administration announced its support for the Superconducting Super Collider as a major investment to push back the frontiers of particle physics. And on 23 February, astronomers ended a 383-year vigil as a naked-eye supernova blazed forth in the southern sky. (See figure 1.)
Leo Szilard: Giving Peace a Chance in the Nuclear Age
Authors: Bernstein Barton J.
Published: January 2008

The idea came to him one day in September 1933 as he crossed Southhampton Row near the British Museum in London. What Leo Szilard imagined so brilliantly that day was a transmutation of chemical elements in a nuclear chain reaction that could someday produce enormous explosive power. Szilard's concept unrolled in his mind five years before fission was discovered, nine years before the first self-sustaining reaction was achieved and 12 years before the atomic bomb was dropped.
Particle Physics and Inflationary Cosmology
Authors: Linde Andrei
Published: January 2008

With the invention of unified theories of strong, weak, electromagnetic and gravitational interactions, elementaryparticle physics has entered a very interesting and unusual stage of its development. The end of the 1960s saw the introduction of the Glashow-Weinberg-Salam unification of the weak and electromagnetic interactions. In 1974 came the grand unified theories of the strong, weak and electromagnetic interactions. Two years later we had supergravity, giving us the first hope of unifying all fundamental interactions, including gravitation. The beginning of the 1980s witnessed a renewal of interest in the Kaluza-Klein theories and supergravity in higher-dimensional space-time. Nowadays superstring theory is the leading candidate for the role of “theory of everything.”
Superstrings
Authors: Schwarz John H.
Published: January 2008

During the past three years many theoretical physicists have dedicated themselves to working on superstring theory. With varying degrees of conviction we believe that we have at hand for the first time many of the essential ingredients for an almost unique quantum theory that gives a unified description of all elementary particles and the forces between them. We also believe that this theory is free from the inconsistencies that have thwarted all previous attempts to construct a “unified field theory” that describes gravity together with the strong, weak and electromagnetic forces. In short, as some popular media like to put it, we may finally have “the theory of everything.”
What Do We Learn from Space? Space Science in Japan
Authors: Oda Minoru
Published: January 2008

This year x-ray astronomy celebrates its silver anniversary. It was in 1962 that Riccardo Giacconi, Herbert Gursky, Frank Paolini and Bruno Rossi found x rays (from Scorpius X-l) coming from outside the Solar System. Freeman Dyson in a talk given at Cornell in 1984 said: “The old quiescent universe of Aristotle, which had survived essentially intact the intellectual revolutions associated with the names of Copernicus, Newton and Einstein, disappeared forever as soon as the x-ray telescopes went to work.” After years of rocket and balloon observations, the first x-ray satellite, Uhuru (Swahili for “Freedom”), was launched in 1970 off the coast of Africa, accelerating the evolution of x-ray astronomy. (See the figure on page 28.)
Research on High-Tc Superconductivity in Japan
Authors: Tanaka Shoji
Published: January 2008

“Will a new age of superconductor technology dawn in the near future and make the current semiconductor technology obsolete?” I wondered in the early 1970s. My research until then had been mostly in semiconductors. Like many a semiconductor physicist, I felt that it was becoming difficult to carry on this research at a university laboratory. Most advances in semiconductor research were being made by that time at laboratories supported by the big industrial corporations. These considerations motivated me to move away from semiconductors, and to think of a new direction for my research.
The First Electronic Computer
Authors: Mackintosh Allan R.
Published: January 2008

Until recently most Europeans interested in computing would have claimed that the first electronic computer was the Colossus, designed and constructed in Bletchley, England, by the mathematician Alan Turing and his colleagues, operational in December 1943 and used to decipher the German Enigma code, with a decisive effect on the course of World War II. Most Americans, on the ther hand, would have given the honor to the Electronic Numerical Integrator and Calculator, built by John W. Mauchly and J. Presper Eckert at the Moore School of Electrical Engineering, University of Pennsylvania, and operational in late 1945.
Forensic Physics of Vehicle Accidents
Authors: Damask Arthur C.
Published: January 2008

Accidents are the third largest cause of death in America, taking 140 000 lives per year. Only heart attacks and cancer kill more people. Vehicular accidents such as the one shown in figure 1 account for 44 000 of the accidental deaths and cause 80 000 permanent disabilities through trauma to the brain or spinal cord. The direct and indirect costs of all automobile accidents run close to $60 billion per year.
Pion Physics at the Meson Factories
Authors: Nagle Darragh E. , Johnson Mikkel B. , Measday David F.
Published: January 2008

Pions are excellent probes of the structure of the nucleus and are useful in a variety of particle physics experiments of fundamental significance. For the past 15 years, physicists have been producing copious beams of these mesons by directing intense proton beams into targets. Three “meson factories” are now in operation: TRIUMF, in Vancouver, British Columbia; SIN, in Villigen, Switzerland; and LAMPF, in Los Alamos, New Mexico. A fourth is under construction in the Soviet Union, at Troitsk, south of Moscow. This article surveys the scientific achievements that have come out of pion experiments at the meson factories since they came into operation and explains how the availability of pions has caused medium-energy physics to burgeon.
Michelson and Measurement
Authors: Swenson Loyd S.
Published: January 2008

Measurement, as much as if not more than mathematics, is the essence of modern natural philosophy and artful invention. To measure is to begin to understand and to manipulate. Yet modern scientific instrumentation is so complex and so thoroughly prepackaged that it is difficult to know enough about what goes on inside the “black boxes” that we use to measure. Only a hundred years ago it was still possible for some people to at least appreciate and for a few to manipulate nearly every instrument in specialized usage. One such person in physical optics was Albert Abraham Michelson, a US naval officer who became a world-renowned experimenter and preeminent master of measurement by light waves largely through his playful work with interferometers and interferometry. Measurement was his mistress and muse, and by virtue of his quest to understand the “innards” of all his instruments, Michelson's name became practically synonymous with extremely precise measurement.