bluuebunny/crossref_metadata_2025 huggingface dataset:
UNESCO/IHD Working Group on Floods and Their Computation, Paris, France May 17”21, 1971
Authors: Anoymous
Published: April 2012

The fourth session of the Working Group was held at Unesco headquarters in May. Participating members were: S.K. Banerjee (India); S. Cavassa (Italy); H. Kikkawa (Japan); W. Meyer (Poland); F.F. Snyder (U.S.);; Chairman A.A. Sokolov (USSR); and V. Stanescu (Romania). M. Podani represented the World Meteorological Organization (WMO) at the meeting.
Measuring soil moisture
Authors: Anonymous
Published: April 2012

Methods of Measuring Soil Moisture, IFYGL Technical Manual Series No. 1, by Richard G. Wilson is published by the Canadian National Committee for the IHD, Joseph MacDowall, Managing Editor, 1971. This 20‐page review covers briefly the principal methods of measuring soil water. Starting with the most simple and progressing to the more complex, it discusses the measurement of soil water content, soil water potential or suction, and, very briefly, soil water movement.
Pollution solution ads
Authors: Adler Cyrus
Published: April 2012

On Page 656 of the September issue of EOS there appeared a column of wastepaper in the form of an ad by the Advertising Council. The ad suggests that readers write for a booklet on ‘71 Things You Can Do to Stop Pollution.’

The Council has circulated other ads with the engaging theme ‘People Start Pollution. People Can Stop It.’ On the surface, this thesis is logically impossible to refute. But what the Council does not do—and understandably so—is to suggest that people can only significantly reduce pollution by changing their life styles and consuming habits.
The President's Page: GAP (Guest Editorial)
Authors: Spilhaus A. F.
Published: April 2012

In the September issue of EOS, Geophysical Abstracts in Press appeared for the first time. GAP is an experiment designed to provide rapid access to a cross section of the literature in geophysics, thereby making research results available immediately after final acceptance for publication. GAP presently includes only AGU journals. Abstracts are processed on the day they arrive in the AGU office from journal editors, normally between three months and four months prior to publication in the journal. The abstracts are published in EOS two to six weeks after receipt. Thus they are available to the research community more than two months before the publication of the full article. Mailing addresses are given for the senior authors, enabling readers to contact them directly for preprints or further information.
The Fast Breeder Reactor: A source of abundant power for the future
Authors: Dieckamp Herman M.
Published: April 2012

The fast breeder reactor is essential to meet the future energy needs of our society. This capability derives from three fundamental factors: (1) the fast breeder reactor maximizes the utilization of valuable natural resources and as a direct result can supply energy to an expanding industrial society for many generations; (2) the fast breeder reactor can achieve this goal while protecting the environment better than any other currently available economic method of generating power; and (3) the fast breeder is based upon established technology and is therefore ready for commercial introduction.
Fossil fuel supplies and future energy needs
Authors: Risser Hubert E.
Published: April 2012

Through the years one of the most significant indexes for measuring a nation's progress has been the per capita consumption of inanimate energy in the performance of work, the production of material goods, and the provision of services. Most of us have seen those charts that show the close parallel between the per capita consumption of energy and per capita income.

Much of the industrial and economic growth of the United States for almost 200 years has been based on an abundance of low‐cost energy. However, recent events have brought increasing evidence that our fuel supplies, though they appear to be vast, are not adequate to support indefinitely an ever‐increasing demand. Furthermore, environmental effects associated with their production and consumption are now a matter of major concern.
Environmental studies center established in South Florida
Authors: Anonymous
Published: April 2012

An environmental studies center offering college‐level instruction and research opportunities in ecology‐related subjects will be established early next year near Florida's Everglades.

The center, Fahkahatchee Environmental Studies Center, is affiliated with Cedar Crest College, Allentown, Pennsylvania, but will be open to students and faculty from all colleges and universities in the nation who are interested in pursuing subtropical environmental studies.
UCLA trains scientists and engineers to deal with environmental problems
Authors: Anonymous
Published: April 2012

A pioneering program aimed at training scientists and engineers to deal with a broad range of environmental problems is being conducted at the University of California, Los Angeles.

Graduate students will embark on a new five‐year doctoral program in environmental science and engineering supported by a National Science Foundation grant. An interdisciplinary educational experiment that cuts across traditional departmental boundaries, the project is under the direction of Willard F. Libby, Director of UCLA's Institute of Geophysics and Planetary Physics.
Meeting on pollution: Engineering and scientific solutions
Authors: Anonymous
Published: April 2012

The Society of Engineering Science has announced that it will begin to sponsor a series of international conferences in addition to its usual annual technical meetings in the U.S. The first such conference will be the First International Meeting, to be held at Tel‐Aviv University, Tel‐Aviv, Israel, June 12–17, 1972. The subject of the meeting is ‘Pollution: Engineering and Scientific Solutions.’ The meeting is cosponsored by the Environmental Protection Agency, the National Oceanic and Atmospheric Administration, and Washington University. The timing of the meeting is such that it allows participants of the First United Nations Conference on the Human Environment to attend at the end of their deliberations. The meeting will be followed a week later by the Sixth International Conference on Water Pollution Research in Jerusalem.
Jack‐in‐the‐box
Authors: Anonymous
Published: April 2012

This extendible boom designed to support a solar array on a potential large space station is being tested by engineers at Lockheed Missiles and Space Company, Inc., in Sunnyvale, California. Built to Lockheed specifications by Astro Research Corporation, Santa Barbara, the boom can be deployed 84 feet and retracted into the 24‐inch diameter ‘can’ in the foreground. The solar array, which obtains energy from the sun, is folded during spacecraft launch, then extended like a wing in space. Solar panels can be exchanged in orbit by use of the Space Shuttle.
New ship and ocean engineering facility for NOAA
Authors: Anonymous
Published: April 2012

The National Oceanic and Atmospheric Administration's new $1,000,000 Ship and Ocean Engineering Facility in Miami, Florida, was dedicated September 2. Following the ceremony, guests toured the four‐building complex and the NOAA ship Discoverer, the oceanographic floating laboratory based at the Miami facility.
Minerals and petroleum exploration survey in Zambia
Authors: Anonymous
Published: April 2012

GeoMetrics, a geophysical instrumentation and services firm based in Palo Alto, California, has just been awarded a contract by the Geological Survey of the Republic of Zambia. The contract covers a large‐scale airborne geophysical survey of more than one‐third of Zambia's land area, which has never before been explored for potential minerals and petroleum development.
Symposium on Societal Problems of Water Resources
Authors: Anonymous
Published: April 2012

Western Illinois University, MacComb, Illinois, will host a Symposium on Societal Problems of Water Resources April 28, 1972. The symposium, which is being held in conjunction with the Sixty‐Fifth Annual Meeting of the Illinois State Academy of Science, is sponsored by the Illinois Earth Science Association, the Illinois State Academy of Science, and the Illinois Natural History Survey. Deadline for submission of abstracts (not exceeding 100 words) is December 1, 1971.
NCAR GARP Task Group formed
Authors: Anonymous
Published: April 2012

A new organization, the GARP Task Group, has been established at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. NCAR, which is sponsored by the National Science Foundation, is operated by the University Corporation for Atmospheric Research. The GARP Task Group was established to strengthen the university community's contribution to the Global Atmospheric Research Program (GARP) by taking on some of the burdens of communications and planning, to promote participation by university scientists in planning and executing GARP experiments, and to provide a focus for the GARP‐related activities, both scientific and engineering, already in progress at NCAR. These include research on global atmospheric circulation, convection, and turbulence; the development of mathematical models, data handling techniques, sensing methods, and complex observing systems; participation in large field projects and involvement in national and international planning for GARP. Such NCAR activities make it appropriate that NCAR should participate in GARP and should assume responslbility for providing mechanisms whereby university scientists can become informed about GARP developments and can become involved in GARP and related projects.
The Sydney Chapman Memorial Lecture Program
Authors: Anonymous
Published: April 2012

In tribute to the memory of the world renowned and revered geophysicist, Sydney Chapman, the University of Alaska and the University of Colorado will join with the National Center for Atmospheric Research and the National Oceanic and Atmospheric Administration's Environmental Research Laboratories to establish an annual lecture series to be known as the Sydney Chapman Memorial Lecture Program.
National Science Foundation Graduate Fellowships for 1972”1973
Authors: Anonymous
Published: April 2012

The National Research Council has been called upon again to advise the National Science Foundation in the selection of candiates for the Foundation's program of graduate fellowships. Panels of outstanding scientists appointed by the Research Council will evaluate applications of candidates. Final selection will be made by the Foundation, with awards to be announced on March 15, 1972.
USNC/URSI‐IEEE call for papers
Authors: Anonymous
Published: April 2012

The 1972 USNC/URSI‐IEEE Spring Meeting will be held April 13–15, 1972, at the Statler Hilton Hotel in Washington, D.C.

The meeting will be held in cooperation with the following IEEE Groups: Antennas and Propagation, Circuit Theory, Geoscience Electronics, Information Theory, Instrumentation and Measurement, and Microwave Theory and Techniques.
The President's Page: Science and public policy lessons from Vela‐Uniform (Guest Editorial)
Authors: Kisslinger Karl
Published: April 2012

In late October of this year, the Joint Committee on Atomic Energy of the U.S. Congress convened hearings to review our national capability to monitor a comprehensive treaty banning nuclear testing, one which would include underground tests. In fee decade since the last such hearings were held, a large fraction of American research in seismology has been dedicated to the solution of the problems of detecting, locating, and identifying underground nuclear explosions. Hundreds of papers based on research carried out under Project Vela‐Uniform have been presented at AGU meetings during this time. The question now is whether a successful program of research on the technical problems involved, mounted in direct response to an expressed national need, will find its full fruition in the formulation of a national policy that could lead to meaningful progress to ward nuclear disarmament.
Earthquake Prediction Program and the People's Republic of China
Authors: Coe Robert S.
Published: April 2012

At five o'clock in the morning of March 8, 1966, a devastating earthquake struck a rural area near Hsingtai, Hopei Province, 300 km southwest of Peking. Although the magnitude was only 6.8 the damage was severe and widespread; over thirty communes in four counties were seriously affected. The official death toll is not available, but, if the village of Sha Wan (which I visited) 30 km from the epicenter is typical, it must have been considerable. Seventy percent of the houses in Sha Wan collapsed and the rest were unfit to live in. Virtually all of its 330 families were left homeless. However, with extensive help from the army and inspiration from the visit of Premier Chou En‐lai, the people of Sha Wan and the other damaged villages quickly rebuilt their houses while they continued their agricultural work. This time they built with brick, mortar, and large wooden beams rather than with mud. Now the area is more prosperous than it was before the earthquake.
Glacier inventory in northern Washington
Authors: Anonymous
Published: April 2012

The North Cascade Mountains in Washington State contain 756 glaciers covering a total of 103 square miles, according to a glacier inventory being compiled by hydrologists of the U.S. Geological Survey. Using aerial and ground reconnaissance, a team of USGS glacial scientists counted and described all glaciers larger than about 25 acres in northeast Washington. The state has about 80% of the glacier‐covered areas of the conterminous states.

The inventory is the first contribution to the part of the program of the International Hydrological Decade designed to make ‘a world inventory of perennial ice and snow masses.’
NSF continues project aimed at better scientific basis of land and water use
Authors: Anonymous
Published: April 2012

The National Science Foundation has announced continuing support of a multifaceted research project aimed ultimately at a better scientific basis for use of land and water resources over a large part of the United States.

The foundation awarded nearly $2 million for a second full year of research under the program. The grant is administered by the Atomic Energy Commission's Oak Ridge National Laboratory (ORNL) under an interagency agreement. Grant funds will be divided among research groups at ORNL, Oak Ridge, Tennessee; the Research Triangle Group (composed of Duke University, Durham, North Carolina; University of North Carolina, Chapel Hill; and North Carolina State University, Raleigh); University of Georgia, Athens; and the University of Wisconsin at Madison.
NRC research associateships for 1972
Authors: Anonymous
Published: April 2012

The National Research Council is offering an associateship program to provide opportunities for basic research and advanced training to scientists and engineers of unusual ability and promise. Three types of associateships are offered.

Resident Research Associateships are awarded to persons with less than five years research experience beyond the doctorate level. The stipend is $13,000 annually in most cases.
JILA Associateship and Fellowship Program for 1972”1973
Authors: Anonymous
Published: April 2012

The Joint Institute for Laboratory Astrophysics at the University of Colorado, Boulder, is devoted to research, study, and teaching in theoretical astrophysics, low‐energy atomic physics, and other closely related areas. Primary interest at present is in the areas of stellar atmospheres, solar physics, stellar stability and the interstellar medium, atomic and molecular collisions, spectroscopy, nonequilibrium statistical mechanics, and optical resonance phenomena. JILA offers two types of programs for visting scientists
IAHR Symposium on River Mechanics
Authors: Anonymous
Published: April 2012

An International Symposium or River Mechanics will be held in Bangkok, Thailand, January 9–12, 1973 under the auspices of the International Association of Hydraulic Research. The symposium will be divided into three technical programs: Flood Investigations, Erosion and Sedimentation, and River and Estuary Model Analysis. Papers are invited and summaries are required before March 1, 1972.
AAS Division for Planetary Sciences Annual Meeting
Authors: Anonymous
Published: April 2012

The Division for Planetary Sciences of the American Astronomical Society will hold its annual meeting in Kailua‐Kona, Hawaii, March 20–24, 1972.

Featured on the program will be the first comprehensive scientific reports of results of the NASA Mariner‐9 Mars orbiter. An invitation has also been extended to the USSR Academy of Sciences to send a delegation to report results from the Soviet spacecraft launched to Mars in 1971. A third special session will be devoted to the natural satellites (excluding the moon), and the remainder of the program will consist of contributed papers in all areas of solar system science. A visit to the Mauna Kea Observatory of the University of Hawaii is planned for March 24, the final day of the meeting.
Recruitment of circulating dendritic cell precursors into the infarcted myocardium and pro-inflammatory response in acute myocardial infarction
Authors: Kretzschmar Daniel , Betge Stefan , Windisch Alexander , Pistulli Rudin , Rohm Ilonka , Fritzenwanger Michael , Jung Christian , Schubert Katja , Theis Bernhard , Petersen Iver , Drobnik Stefanie , Mall Gita , Figulla Hans-Reiner , Yilmaz Atilla
Published: April 2012

DC (dendritic cells) play an important role in the immune system. They invade peripheral tissues to detect harmful antigens, inducing a local immune response. Studies suggest that DCPs (dendritic cell precursors) might be reduced in AMI (acute myocardial infarction); however, the reason for their reduction is unknown yet. In the present study, circulating mDCPs (myeloid DCPs), pDCPs (plasmacytoid DCPs), tDCPs (total DCPs) and serum levels of TNFα (tumour necrosis factor α), IL (interleukin)-2, -4, -5, -6, -10 and -12 were analysed by flow cytometry in blood of patients with NSTEMI [non-STEMI (ST-segment elevation myocardial infarction)] (n=44) and STEMI (n=34) compared with controls with excluded CAD (coronary artery disease) (n=45). Post-mortem myocardial specimens of patients with AMI (n=12) and healthy myocardium of accident victims (n=10) were immunostained for mDCs (myeloid dendritic cells) T-cells and macrophages. Compared with controls, in patients with AMI a significant decrease in circulating mDCPs, pDCPs and tDCPs was observed (each P<0.0001). The extent of the decrease was higher in STEMI than NSTEMI patients. Serum levels were significantly higher in patients with AMI compared with controls for IL-6, -10, -12 and TNFα (each P<0.03). Immunostaining revealed significantly higher number of DCs, T-cells and macrophages (each P<0.002) in infarcted than control myocardium. We show that circulating DCPs are significantly reduced in AMI, with a pronounced reduction in STEMI patients. This was accompanied by a significant increase of inflammatory serum cytokines in patients with AMI. Immunohistochemical analysis unravelled that the reduction of circulating DCPs might be due to recruitment into the infarcted myocardium.
Analysis of the Brunel model and resulting hot electron spectra
Authors: Mulser P. , Weng S. M. , Liseykina Tatyana
Published: April 2012

Among the various attempts to model collisionless absorption of intense and superintense ultrashort laser pulses, the so-called Brunel mechanism plays an eminent role. A detailed analysis reveals essential aspects of collisionless absorption: Splitting of the electron energy spectrum into two groups under p-polarization, prompt generation of fast electrons during one laser cycle or a fraction of it, insensitivity of absorption with respect to target density well above nc, robustness, simplicity, and logical coherence. Such positive aspects contrast with a non-Maxwellian tail of the hot electrons, too low energy cut off, excessively high fraction of fast electrons, and inefficient absorption at moderate angles of single beam incidence and intensities. Brunel’s pioneering idea has been the recognition of the role of the space charges induced by the electron motion perpendicular to the target surface that make irreversibility possible. By setting the electrostatic fields inside the overdense target equal to zero, anharmonic resonance and mixing of layers leading to Maxwellianization are excluded. To what extent the real electron spectra and their scaling on laser intensity are the product of the interplay between Brunel’s mechanism and anharmonic resonance is still an open question.
Dynamics of the sputtering of water from ice films by collisions with energetic xenon atoms
Authors: Killelea Daniel R. , Gibson K. D. , Yuan Hanqiu , Becker James S. , Sibener S. J.
Published: April 2012

The flow of energy from the impact site of a heavy, translationally energetic xenon atom on an ice surface leads to several non-equilibrium events. The central focus of this paper is on the collision-induced desorption (sputtering) of water molecules into the gas-phase from the ice surface. Sputtering is strongly activated with respect to xenon translational energy, and a threshold for desorption was observed. To best understand these results, we discuss our findings in the context of other sputtering studies of molecular solids. The sputtering yield is quite small; differential measurements of the energy of xenon scattered from ice surfaces show that the ice efficiently accommodates the collisional energy. These results are important as they quantitatively elucidate the dynamics of such sputtering events, with implications for energetic non-equilibrium processes at interfaces.
Experimental investigation of energy and exergy efficiencies of domestic size parabolic dish solar cooker
Authors: Panwar N. L. , Kaushik S. C. , Kothari Surendra
Published: April 2012

This paper deals with an energy and exergy analysis of a domestic size parabolic solar cooker in actual use. The experimental time period was from 10:00 to 13:30 solar time. During the experiment, it was found that the maximum temperature of water was 368 K. The energy out of the cooker varied between 46.67 and 653.33 W, whereas its exergy output was in the range, 7.37-46.46 W. Maximum energy and exergy efficiencies of the cooker were experimentally evaluated, and it was about 46.82% and 32.97%, respectively. Over the time, both efficiencies were decreased because of the optical and thermal losses from the reflector and pot. By using properly insulated cooking pot, the considerable amount of conventional energy can be saved. Regular use of a solar cooker helps in CO2 mitigation and provides clean and safe cooking.
Coupled-monomers in molecular assemblies: Theory and application to the water tetramer, pentamer, and ring hexamer
Authors: Wang Yimin , Bowman Joel M.
Published: April 2012

We present extensions to the local-monomer (LMon) Model, a general quantum method to describe coupled intramolecular vibrational modes of a molecular cluster consisting of a set of monomers [Y. Wang and J. M. Bowman, J. Chem. Phys. 134, 154510 (2011)]10.1063/1.3579995, to incorporate monomer-monomer coupling. A central aspect of the LMon model is a local normal-mode analysis, done for each monomer, perturbed by all other mononers. Monomer-monomer coupling is described by several approaches based on these normal-mode analyses. Two are Hückel-type models, where coupling constants for each intramolecular mode are determined non-empirically from normal-mode analyses. One model, the simple one, is limited to nearest-neighbor interactions. The second and more general one determines monomer-monomer couplings from the full and local-monomer Hessians, with no further assumptions. The simple approach is applied to the water tetramer, pentamer and ring hexamer. For the tetramer and ring hexamer cases, artificial degeneracies of the intramolecular energies in the LMon model, owing to the high symmetry of the cluster, are correctly lifted. The general approach to obtain coupling constants is illustrated for the ring hexamer, where new fundamental energies are reported. Other, more rigorous approaches are suggested but not implemented.
Recursion operators and conservation laws for discrete Lax equations
Authors: Li Hong-Min , Li Biao , Li Yu-Qi
Published: April 2012

In this paper, a method for constructing recursion operator of discrete Lax equations is proposed. To illustrate the method, recursion operators for discrete Boussinesq equation and discrete KdV equation are obtained. Then the recursion operators of continuous Boussinesq equation and KdV equation are successfully recovered by the discrete ones. Infinitely many conservation laws of discrete Boussinesq equation are constructed by the discrete residue formula and the first three conserved quantities are given explicitly and verified numerically. Existence of recursion operators and infinite number of conservation laws proves the integrability of the discrete Lax equations.
Variation of the electron energy distribution with He dilution in an inductively coupled argon discharge
Authors: Lee Hyo-Chang , Chung Chin-Wook
Published: April 2012

We present experimental evidence of different behaviors of plasma parameters depending on changes in the electron energy distribution (EED), caused by an electron heating mechanism and electron-neutral collision processes in an Ar/He mixture inductively coupled plasma. At a low gas pressure of 3 mTorr, where the electron neutral collision frequency νm is much smaller than the driving frequency ωRF, the EEDs evolved from a bi-Maxwellian distribution to a Maxwellian distribution, due to the efficient heating of low energy electrons when the He flow rate increased at a fixed total gas pressure. The plasma density slowly decreased with the He flow rate portion ([He]/[Ar] + [He]) in a range of 0%–70%, while the plasma density largely decreased in the He flow rate portion of 70%–100%. On the other hand, at a high gas pressure of 350 mTorr where νm ≫ ωRF, the EEDs evolved from a Druyvesteyn-like distribution to a Maxwellian distribution, due to a cooling of low energy electrons and an increase in the population of high energy electrons, when the mixing ratio of the He gas is increased. In this case, plasma density abruptly decreased for a He flow rate ratio of 0%–30%. This result directly shows that the EEDs significantly affect the different variations of plasma parameters, even in the case of the same mixing ratio of the gases.
A photodiode amplifier system for pulse-by-pulse intensity measurement of an x-ray free electron laser
Authors: Kudo Togo , Tono Kensuke , Yabashi Makina , Togashi Tadashi , Sato Takahiro , Inubushi Yuichi , Omodani Motohiko , Kirihara Yoichi , Matsushita Tomohiro , Kobayashi Kazuo , Yamaga Mitsuhiro , Uchiyama Sadayuki , Hatsui Takaki
Published: April 2012

We have developed a single-shot intensity-measurement system using a silicon positive-intrinsic-negative (PIN) photodiode for x-ray pulses from an x-ray free electron laser. A wide dynamic range (103–1011 photons/pulse) and long distance signal transmission (>100 m) were required for this measurement system. For this purpose, we developed charge-sensitive and shaping amplifiers, which can process charge pulses with a wide dynamic range and variable durations (ns-μs) and charge levels (pC-μC). Output signals from the amplifiers were transmitted to a data acquisition system through a long cable in the form of a differential signal. The x-ray pulse intensities were calculated from the peak values of the signals by a waveform fitting procedure. This system can measure 103–109 photons/pulse of ∼10 keV x-rays by direct irradiation of a silicon PIN photodiode, and from 107–1011 photons/pulse by detecting the x-rays scattered by a diamond film using the silicon PIN photodiode. This system gives a relative accuracy of ∼10−3 with a proper gain setting of the amplifiers for each measurement. Using this system, we succeeded in detecting weak light at the developmental phase of the light source, as well as intense light during lasing of the x-ray free electron laser.
Soft x-ray scattering facility at the Advanced Light Source with real-time data processing and analysis
Authors: Gann E. , Young A. T. , Collins B. A. , Yan H. , Nasiatka J. , Padmore H. A. , Ade H. , Hexemer A. , Wang C.
Published: April 2012

We present the development and characterization of a dedicated resonant soft x-ray scattering facility. Capable of operation over a wide energy range, the beamline and endstation are primarily used for scattering from soft matter systems around the carbon K-edge (∼285 eV). We describe the specialized design of the instrument and characteristics of the beamline. Operational characteristics of immediate interest to users such as polarization control, degree of higher harmonic spectral contamination, and detector noise are delineated. Of special interest is the development of a higher harmonic rejection system that improves the spectral purity of the x-ray beam. Special software and a user-friendly interface have been implemented to allow real-time data processing and preliminary data analysis simultaneous with data acquisition.
Free magnetohydrodynamic shear layers in the presence of rotation and magnetic field
Authors: Spence E. J. , Roach A. H. , Edlund E. M. , Sloboda P. , Ji H.
Published: April 2012

We present an experimental and numerical study of hydrodynamic and magnetohydrodynamic free shear layers and their stability. We first examine the experimental measurement of globally unstable hydrodynamic shear layers in the presence of rotation and their range of instability. These are compared to numerical simulations, which are used to explain the modification of the shear layer, and thus the critical Rossby number for stability. Magnetic fields are then applied to these scenarios and globally unstable magnetohydrodynamic shear layers generated. These too are compared to numerical simulations showing behavior consistent with the hydrodynamic case and previously reported measurements.
Self consistent model for ponderomotive ion acceleration of laser irradiated two species dense target plasmas
Authors: Sinha Ujjwal
Published: April 2012

Acceleration of ions using ultra-intense laser irradiated on an overdense target plasma composed of two ion species has been described using a self consistent approach. The analytical model for the steady state described here gives a complete description of the charge separation zone, i.e., ion space charge and electron sheath, created due to ponderomotive force of the laser. It successfully explains the jump in electrostatic potential or field in the laser piston responsible for a major part of the acceleration. The information about the structure of laser piston obtained from the analytical model is used for the stability analysis of the process. It has been found that the stability of the laser piston depends on the target composition. The reflection of incoming ion beams from the coulomb exploding region of the ion space charge has been described in context of the charge on the incident beam species.
Nature of energetic ion transport by ion temperature gradient driven turbulence and size scaling
Authors: Chowdhury J. , Wang W. , Ethier S. , Manickam J , Ganesh R.
Published: April 2012

Energetic ion transport has been studied using a global gyrokinetic nonlinear simulation in the presence of ion temperature gradient (ITG) driven turbulence. The measured transport and its nature show dependence on the system size of the tokamak expressed as the ratio of plasma minor radius (a) to the thermal ion Larmor radius (ρi). It increases with system size initially and then tends to saturate at larger system size. The nature of transport, on the other hand, exhibits nondiffusive character for smaller system size which eventually becomes diffusive one as the system size becomes larger.
Sheet-like assemblies of spherical particles with point-symmetrical patches
Authors: Mani Ethayaraja , Sanz Eduardo , Roy Soumyajit , Dijkstra Marjolein , Groenewold Jan , Kegel Willem K.
Published: April 2012

We report a computational study on the spontaneous self-assembly of spherical particles into two-dimensional crystals. The experimental observation of such structures stabilized by spherical objects appeared paradoxical so far. We implement patchy interactions with the patches point-symmetrically (icosahedral and cubic) arranged on the surface of the particle. In these conditions, preference for self-assembly into sheet-like structures is observed. We explain our findings in terms of the inherent symmetry of the patches and the competition between binding energy and vibrational entropy. The simulation results explain why hollow spherical shells observed in some Keplerate-type polyoxometalates (POM) appear. Our results also provide an explanation for the experimentally observed layer-by-layer growth of apoferritin - a quasi-spherical protein.
Improved delay-leaping simulation algorithm for biochemical reaction systems with delays
Authors: Yi Na , Zhuang Gang , Da Liang , Wang Yifei
Published: April 2012

In biochemical reaction systems dominated by delays, the simulation speed of the stochastic simulation algorithm depends on the size of the wait queue. As a result, it is important to control the size of the wait queue to improve the efficiency of the simulation. An improved accelerated delay stochastic simulation algorithm for biochemical reaction systems with delays, termed the improved delay-leaping algorithm, is proposed in this paper. The update method for the wait queue is effective in reducing the size of the queue as well as shortening the storage and access time, thereby accelerating the simulation speed. Numerical simulation on two examples indicates that this method not only obtains a more significant efficiency compared with the existing methods, but also can be widely applied in biochemical reaction systems with delays.
Absolute Helmholtz free energy of highly anharmonic crystals: Theory vs Monte Carlo
Authors: Yakub Lydia , Yakub Eugene
Published: April 2012

We discuss the problem of the quantitative theoretical prediction of the absolute free energy for classical highly anharmonic solids. Helmholtz free energy of the Lennard-Jones (LJ) crystal is calculated accurately while accounting for both the anharmonicity of atomic vibrations and the pair and triple correlations in displacements of the atoms from their lattice sites. The comparison with most precise computer simulation data on sublimation and melting lines revealed that theoretical predictions are in excellent agreement with Monte Carlo simulation data in the whole range of temperatures and densities studied.
Controlling energy transfer processes and engineering luminescence efficiencies with low dimensional doping
Authors: Yu Xiaoqiang , Summers Christopher J. , Park Wounjhang
Published: April 2012

Energy transfer between two optical centers has long been used to promote the down- and up-conversion of light. In conventional phosphors, the two centers are distributed uniformly in 3D space and the luminescence efficiency is generally limited by energy transfer to defect states, where the excitation is quenched through non-radiative processes. In this paper, we present a new concept of low-dimensional doping of pairs of optical centers and explore its effect on enhancing the efficiency of down- and up-converted luminescence. The concept takes advantage of the fact that the low-dimensional doping profile significantly reduces the energy transfer rate to unintentional defects, which are naturally distributed in 3D space. The resultant de-coupling between optical centers and defects can lead to a substantial increase in luminescence efficiency.

We first present the theoretical framework and apply the theory to well-characterized down- and up-conversion phosphors. For BaMgAl10O17:Eu2+, Mn2+ down-conversion phosphor, a factor of two increase in efficiency is predicted. For Na2Y3F11:Yb3+, Er3+ up-conversion phosphor, low-dimensional doping did not lead to increase in efficiency. This is because the major quenching mechanism is cross-relaxation between Er3+ ions, not energy transfer to defects. In an ideal up-conversion phosphor, where defect quenching is the dominant loss mechanism, similar increases (by a factor of 2–5) are predicted. This work presents a new pathway to engineer luminescent materials and achieve high luminescence efficiencies in up- and down-conversion phosphors.
Electrical and optical properties of sputtered amorphous vanadium oxide thin films
Authors: Podraza N. J. , Gauntt B. D. , Motyka M. A. , Dickey E. C. , Horn M. W.
Published: April 2012

Amorphous vanadium oxide (VOx) is a component found in composite nanocrystalline VOx thin films. These types of composite films are used as thermistors in pulsed biased uncooled infrared imaging devices when containing face centered cubic vanadium monoxide phase crystallites, and substantial fractions of amorphous material in the composite are necessary to optimize device electrical properties. Similarly, optoelectronic devices exploiting the metal-to-semiconductor transition contain the room-temperature monoclinic or high-temperature (>68 °C) rutile vanadium dioxide phase. Thin films of VOx exhibiting the metal-to-semiconductor transition are typically polycrystalline or nanocrystalline, implying that significant amounts of disordered, amorphous material is present at grain boundaries or surrounding the crystallites and can impact the overall optical or electronic properties of the film. The performance of thin film material for either application depends on both the nature of the crystalline and amorphous components, and in this work we seek to isolate and study amorphous VOx. VOx thin films were deposited by pulsed dc reactive magnetron sputtering to produce amorphous materials with oxygen contents ≥2, which were characterized electrically by temperature dependent current-voltage measurements and optically characterized by spectroscopic ellipsometry. Film resistivity, thermal activation energy, and complex dielectric function spectra from 0.75 to 6.0 eV were used to identify the impact of microstructural variations including composition and density.
Using filtering effects to identify objects
Authors: Carroll T. L. , Rachford Frederic J.
Published: April 2012

Reflecting signals off of targets is a method widely used to locate objects, but the reflected signal also contains information that can be used to identify the object. In radar or sonar, the signal amplitudes used are small enough that only linear effects are present, so we can consider the effect of the target on the signal as a linear filter. Using the known effects of linear filters on chaotic signals, we can create a reference that allows us to match a particular target to a particular reflected signal. Furthermore, if some parts of this “filter” vary only slowly as the aspect angle of the object changes, we can produce a reference that averages out the parts that are highly angle dependent so that one reference can be used to identify the target over a range of angles.
Design and modeling of InAs/GaSb type II superlattice based dual-band infrared detectors
Authors: Ariyawansa Gamini , Grupen Matt , Duran Joshua M. , Scheihing John E. , Nelson Thomas R. , Eismann Michael T.
Published: April 2012

The objective of this paper is to provide a credible analysis for predicting the spectral responsivity of InAs/GaSb/AlSb type-II superlattice (T2SL) based dual-band infrared photodetectors. An overview of the T2SL based design criteria is given and new dual-band detector architecture with a model dual-band detector structure designed to detect light in the mid-wave infrared (MWIR) and long-wave infrared (LWIR) ranges is presented. The absorption coefficient is modeled empirically and the quantum efficiency spectra are calculated using a numerical model and Hovel’s analytical expressions. The spectral cross-talk due to the response of the LWIR channel to residual MWIR light is also investigated. It is shown that the significance of this cross-talk primarily depends on the temperature of the target (scene) being detected. For MWIR/MWIR (two bands in the MWIR range) dual-band detectors, the spectral cross-talk becomes significant irrespective of the target temperature. Eliminating the spectral cross-talk in T2SL dual-band detectors presently remains a challenge.
Nuclear dynamics and spectator effects in resonant inelastic soft x-ray scattering of gas-phase water molecules
Authors: Weinhardt Lothar , Benkert Andreas , Meyer Frank , Blum Monika , Wilks Regan G. , Yang Wanli , Bär Marcus , Reinert Friedrich , Heske Clemens
Published: April 2012

The electronic structure of gas-phase H2O and D2O molecules has been investigated using resonant inelastic soft x-ray scattering (RIXS). We observe spectator shifts for all valence orbitals when exciting into the lowest three absorption resonances. Strong changes of the relative valence orbital emission intensities are found when exciting into the different absorption resonances, which can be related to the angular anisotropy of the RIXS process. Furthermore, excitation into the 4a1 resonance leads to nuclear dynamics on the time scale of the RIXS process; we find evidence for vibrational coupling and molecular dissociation in both, the spectator and the participant emission.
Structures and orientations of cobalt phthalocyanine adsorbed on Sb(111)
Authors: She Limin , Yu Yinghui , Wu Ping , Zhang Yun , Qin Zhihui , Huang Min , Cao Gengyu
Published: April 2012

The structures and orientations of cobalt phthalocyanine (CoPc) adsorbed on Sb(111) were investigated by low-temperature scanning tunneling microscope. We found that at the initial coverage molecular domains formed both on the terraces and at the vicinity of step edges that were saturated by molecular chains in advance. With the increasing of molecular coverage, the alternately arranged molecular rows of CoPc adsorbed on the bridge sites of Sb(111) and the orientations of them were rotated by 14° ± 2° with respect to the [-101] direction. At the coverage above one monolayer, the molecules of the second layer were assembled along the directions of the underlying molecular rows and showed similar configurations. Consequently, the second-layer CoPc molecules interacted with neighboring molecules via π orbitals, resulting in the observation of overlapped molecular orbitals.
Identification of a paramagnetic recombination center in silicon/silicon-dioxide interface
Authors: Matsuoka T. , Vlasenko L. S. , Vlasenko M. P. , Sekiguchi T. , Itoh K. M.
Published: April 2012

A paramagnetic recombination center having an orthorhombic symmetry with g[110] = 2.0095(2), g[001] = 2.0038(2), and g[1¯10] = 2.0029(2) is found at the interface between silicon and native oxide. The center is referred to Pm center and observed by a spin dependent recombination based electron paramagnetic resonance detection that has the sensitivity of ∼1011 spins/cm2. The employment of an isotopically enriched 28Si sample with the concentration of 29Si nuclear spins reduced to 0.017% leads to narrowing of the resonance line. This narrowing is the key for the accurate determination of the angular dependence of the g-factor.
Reliability improvement of InGaZnO thin film transistors encapsulated under nitrogen ambient
Authors: Wu Chun-Yu , Cheng Huang-Chung , Wang Chao-Lung , Liao Ta-Chuan , Chiu Po-Chun , Tsai Chih-Hung , Fang Chun-Hsiang , Lee Chung-Chun
Published: April 2012

The nitrogen ambient encapsulation (NAE) technique is introduced to improve the reliability issue for the amorphous InGaZnO (a-IGZO) thin-film transistors under positive gate bias stress (PGBS). For the NAE devices, the threshold voltage (Vth) shift is significantly decreased from 1.88 to 0.09 V and the reduction of saturation drain current is improved from 15.75 to 5.61 μA as compared to the bare a-IGZO counterparts after PGBS. These improvements are attributed to the suppression of negatively charged oxygen adsorption on the a-IGZO backsurface and thereby well maintain the channel potential of NAE devices, which in turn sustain the Vth during PGBS.
Dual resonance excitation system for the contact mode of atomic force microscopy
Authors: Kopycinska-Müller M. , Striegler A. , Schlegel R. , Kuzeyeva N. , Köhler B. , Wolter K.-J.
Published: April 2012

We propose an improved system that enables simultaneous excitation and measurements of at least two resonance frequency spectra of a vibrating atomic force microscopy (AFM) cantilever. With the dual resonance excitation system it is not only possible to excite the cantilever vibrations in different frequency ranges but also to control the excitation amplitude for the individual modes. This system can be used to excite the resonance frequencies of a cantilever that is either free of the tip-sample interactions or engaged in contact with the sample surface. The atomic force acoustic microscopy and principally similar methods utilize resonance frequencies of the AFM cantilever vibrating while in contact with the sample surface to determine its local elastic modulus. As such calculation demands values of at least two resonance frequencies, two or three subsequent measurements of the contact resonance spectra are necessary. Our approach shortens the measurement time by a factor of two and limits the influence of the AFM tip wear on the values of the tip-sample contact stiffness. In addition, it allows for in situ observation of processes transpiring within the AFM tip or the sample during non-elastic interaction, such as tip fracture.
Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects
Authors: Courtney Amy C. , Andrusiv Lubov P. , Courtney Michael W.
Published: April 2012

This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high-speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27–79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5–5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile.
Tunable terahertz optical antennas based on graphene ring structures
Authors: Liu Penghong , Cai Wei , Wang Lei , Zhang Xinzheng , Xu Jingjun
Published: April 2012

Highly tunable optical antennas in teraherz range based on graphene ring structures are proposed, which employ graphene plasmons instead of traditional metallic plasmons. The plasmon resonances of the perfect graphene ring (PGR) can be understood with the edge plasmons in graphene ribbons. While in the nonconcentric graphene ring, the multipolar plasmon modes appear and anti-symmetric mode splits due to symmetry breaking. Furthermore, the symmetric plasmon mode in a graphene ring can concentrate electromagnetic field with an enhancement factor as large as 103 in terahertz waveband, which is almost 20 times larger than a gold ring with the same size.