bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation studies on gas-to-particle conversion processes in the stratosphere by using ultraviolet SR (abstract)
Authors: Suzuki I. H. , Koike M. , Nakae S. 
Published: July 2002

Since stratospheric particles have a possibility to make a large effect on the climate in a global scale, a number of observations have been carried out using different techniques.1 Those particles were found to consist of mainly sulfuric acid and to be 0.1–1.0 μm in size. Turco and co-workers proposed a model that the particles are formed through chemical and physical processes initiated by photodissociation of OCS (λ&lt;2600 A).2 In order to examine this model, a simulation experiment in a laboratory system has been planned, in which ultraviolet components of SR are utilized. An optical system including a Seya-Namioka monochromator has been designed, constructed, and tuned precisely.3 In this system, the first prefocusing mirror (sphere) deflects the SR beam horizontally by 30°, and the second and the third ones (sphere) focus the beam vertically onto the entrance slit of the monochromator. The grating radius is 0.5 m. The monochromatized photon beam is reflected into the horizontal direction by the postfocusing mirror (toroid). A ray-tracing calculation was performed, and the obtained spot diagrams showed that the widths of the rays are about 100 μm at the two slits, and the spot size is 1.5×0.8 mm2 at the experimental point.
These calculated results were confirmed experimentally by using visible and ultraviolet components of SR. From an estimation on the rate of the particle formation using the data available in the literature, the rate determining step was found to be the photodissociation of OCS in the ultraviolet region. At first, the photoabsorption spectra (cross section) were measured at room temperature and at −80 °C (near to the stratospheric temperature). The spectrum is composed of a broad band centered at 2250 Å and of a number of small peaks. Photodissociation rates of OCS at several altitudes have been calculated using the present cross-section values, which indicated that the life of OCS is about 15 years at 20 km and two months at 30 km. It is known that CO and S are formed through the photodissociation of OCS. A computer-controlled mass spectrometer was made for pursuit of the time variation of CO density in the reaction cell, in which the sample gas, a few percent OCS in He, is introduced and irradiated by the photon beam. A chamber has been designed and constructed, in which a pseudostratospheric air is being irradiated by the ultraviolet radiation. A particle counter of laser-scattering type is being connected to this chamber in order to observe the particle number in it. The present study is the first examination applying SR to problems in the stratosphere as a simulated solar radiation. The obtained results have shown opening a new scientific opportunity in the utilization of SR.
Atomic microstructure and electronic properties of a-SiNx:H deposited by radio frequency glow discharge
Authors: Maeda Keiji , Umezu Ikurou 
Published: July 2002

a-SiNx:H films of various composition x were deposited by rf glow discharge (GD). The deposition rate was analyzed for three ranges of gas flow ratio R = [NH3]/[SiH4] depending on the deposition mechanism. Properties of these films were measured by means of x-ray photoelectron spectroscopy (XPS), infrared (IR) absorption, optical absorption, and the temperature dependence of electrical conductivity. The composition x was determined by XPS. For large values of R, x was found to be saturated at 1.7. The variation of H content was detected by IR absorption. The variation of coordinating atoms of Si with increasing x was deduced from the variation of XPS spectra of the Si 2p core-level and the shift of Si-H stretching vibration frequency in IR absorption. Based on the random bonding model and assuming bonding units to the central Si atom to be Si, N, and NH, probabilities of Si tetrahedra with various coordinating units were obtained. The results indicate that there are many Si—Si bonds for the stoichiometric x=1.33 and that the concentration of Si—Si bonds diminishes at around the saturation value x=1.7. These results seem to imply that the presence of Si—Si bonds to some extent is a prerequisite condition for film deposition by GD. Experimental results of optical absorption analyzed by Tauc relation revealed the presence of two kinds of x region whose properties are quite different.
For x&lt;1.5, its optical absorption is similar to a-Si:H modified by the presence of N. With increasing x, the optical band gap EO increases and B coefficient in the Tauc plot decreases. At about x=1.5, Si—Si bonding effectively disappears and the optical absorption abruptly changes to that similar to β-Si3N4. Considering these results, the change of electronic band structure with x was deduced on the basis of the atomic structure obtained above and by the tight binding approximation. For x&lt;1.5, the optical band gap is due to Si—Si bonding, the energy gap of which increases, and the linear band tail becomes broad with increasing x. From the observed temperature dependence of conductivity, variations of the activation energy and pre-exponential factor are obtained with x up to x=1.0. For the decrease of conductivity with x, the contribution from the pre-exponential factor is much larger than that from the activation energy. This result can be understood by a transport mechanism in the electronic band structure obtained above. Finally, it is concluded that the electronic properties of a-SiNx:H deposited by GD ran.
Numerical methods and measurement systems for nonlinear magnetic circuits (abstract)
Authors: Heitbrink Axel , Dieter Storzer Hans , Beyer Adalbert 
Published: July 2002

In the past years an increasing interest in calculation methods of circuits containing magnetic nonlinearities could be observed. For this reason a new method was developed which makes it possible to calculate the steady state solution of such circuits by the help of an interactive cad program. The modular concept of the software allows to separate the circuit into nonlinear and linear subnetworks. When regarding nonlinear magnetic elements one can choose between several numerical models for the description of the hysteresis loops or an inbuilt realtime measurement system can be activated to get the dynamic hysteresis loops. The measurement system is also helpful for the parameter extraction for the numerical hysteresis models. A modified harmonic-balance algorithm and a set of iteration schemes is used for solving the network function. The combination of the realtime measurement system and modern numerical methods brings up a productive total concept for the exact calculation of nonlinear magnetic circuits. A special application class will be discussed which is given by earth-leakage circuit breakers. These networks contain a toroidal high permeable NiFe alloy and a relay as nonlinear elements (cells) and some resistors, inductors, and capacitors as linear elements. As input dc signals at the primary winding of the core any curveform must be regarded, especially 135° phasecutted pulses. These signals with extreme higher frequency components make it impossible to use numerical models for the description of the nonlinear behavior of the core and the relays. So for both elements the realtime measurement system must be used during the iteration process.
During each iteration step the actual magnetization current is sent to the measurement system, which measures the dynamic hysteresis loop at the probe. These values flow back into the iteration process. A graphic subsystem allows a look at the waveforms of all voltages and current when the iterations take place. One can determine how the steady state is reached, especially when one discusses different iteration methods. All parameters of interest, such as geometric data of the core, number of windings, and the linear elements can vary within the computer program and as a result all voltages and currents in the network stand can be used. With the help of this computer controlled measurement system and several iteration methods fast circuit design and optimization can be done.
Hydrogen passivation and its effects on carrier trapping by dislocations in InP/GaAs heterostructures
Authors: Chatterjee B. , Ringel S. A. 
Published: July 2002

In previous work we reported on the stable passivation of dislocations in InP/GaAs heterostructures by plasma hydrogenation (Chatterjee et al., Appl. Phys. Lett. vol. 65, p. 58, 1994). In this article we investigate and compare the trapping kinetics and general trapping properties of dislocations in strain relaxed p-InP grown on GaAs by metalorganic chemical vapor deposition prior to and after hydrogen passivation using deep level transient spectroscopy (DLTS) and current-voltage-temperature (I-V/T) measurements to determine the complete role of hydrogen passivation in these heterostructures. Three hole traps, T1A, T1B, and T2, were detected and attributed to dislocations in heteroepitaxial p-InP which displayed the logarithmic capture kinetics, extended dependence on fill pulse time, and broadened DLTS features expected for dislocation related traps. Quantitative analysis of the DLTS characteristics revealed progressive asymmetry in DLTS peak shape, an increase in characteristic peak width, and a decrease in activation energy as fill pulse time is increased until saturation values were reached.
These observations are explained on the basis of a distribution or band of energy states for each trap resulting from the interaction of electrically active sites either between closely spaced dislocations or along dislocation cores within the strain-relaxed InP. For fill pulse times increasing from 1 μs to 10 ms, activation energies for T1A decreased monotonically from 0.80 to 0.65 eV, for T1B from 0.56 to 0.45 eV, and for T2 from 0.45 to 0.35 eV, with saturation occurring at the upper and lower limits for each trap, which indicates a qualitative measure of the energy spread for each trap. Plasma hydrogenation was not only found to passivate dislocations by reducing the trap concentration from ∼6×1014 to ∼3×1012 cm−3 for a 2 h exposure, but also strikingly altered their basic trapping properties. The qualitative measure of energy spread for the T1A and T2 traps were narrowed from ∼100 to 150 meV to ∼20 to 30 meV after a 2 h hydrogen exposure, whereas T1B was not detected after passivation. In addition, a simultaneous reduction in fill pulse saturation time, DLTS peak broadening, and peak shift as a function of hydrogen exposure time were observed. These observations suggest that hydrogen passivation modifies the dislocation trapping characteristics toward a more point defectlike behavior due to an increase in the average spacing between electrically active dislocation sites. This in turn reduces the interactions between these sites and narrows the distribution of states within each defect band. Further, reverse bias I-V/T measurements revealed that the near midgap trap T1A, which was found to dominate the space charge generation current prior to passivation, is no longer dominant after hydrogen passivation. Instead a 2 h hydrogen treatment shifted the dominant center to an activation energy which more closely matches the shallow T2 level.
Magnetic properties of melt-quenched Ni-rich amorphous and bcc Zr–Ni alloys (abstract)
Authors: Kiss László F. , Varga Lajos K. , Bakonyi Imre 
Published: July 2002

It has been demonstrated recently that the structure of melt-quenched Zr–Ni ribbons in the vicinity of 90 at. % Ni was strongly dependent on the quenching rate: at the highest quenching rate, the alloys Zr10Ni90 and Zr9Ni91 could be prepared with an amorphous structure whereas at lower quenching rates the Zr9Ni91 alloy was prepared as a solid solution of Zr in Ni with a body-centered cubic (bcc) structure. In a preliminary measurement we have established a Curie point (Tc) of 66 K for the a-Zr9Ni91 ribbon which was much smaller than the value Tc=235 K reported for an a-Zr10Ni90 ribbon. This discrepancy has motivated us to perform the present detailed magnetization study in the temperature range 5 to 300 K. It was also of interest to compare the Curie point of the amorphous and bcc phase with the same chemical composition. The real component χ′ of the AC susceptibility as well as the magnetization isotherms up to H=18.5 kOe have been investigated. The measurements of χ′ yielded T=41, 66, and 70 K for a-Zr10Ni90, a-Zr9Ni91, and bcc-Zr9Ni91 ribbons, respectively. The para-ferromagnetic transitions were found to be fairly sharp although in some of these samples several transitions differing by a few degrees only could be observed. In some of the samples, however, very faint magnetic transitions indicated by a small broad peak could also be detected around 250 K. This feature can be attributed to some residual phases of either an unknown Zr–Ni intermetallic compound or of Ni(Zr) solid solution precipitates.
The close coincidence of this peak with the Curie temperature reported by Kaul suggests that his value (Tc=235 K) cannot be representative of the amorphous Zr–Ni matrix but it rather may originate from ferromagnetic precipitates. The magnetization isotherms for the amorphous and bcc-Zr9Ni91 alloy indicated the development of a significant magnetization around the Tc values deduced from χ′. The saturation magnetization at the lowest temperature amounted to about 7 emu/g in both structural modifications. This value is reasonable in view of the reduction of Tc with respect to pure fcc-Ni. The present Tc data indicate that the critical concentration for the onset of magnetic ordering in the Zr–Ni system should be slightly below 90 at. % Ni. It can be concluded from this study that the magnetic behavior of Zr–Ni alloys at about 90 at. % Ni content is characteristic for very weak itinerant ferromagnets and the results will be analyzed in this framework with the help of Arrott plots.
Relationship between HIV‐1 viral load and continued drug use in untreated infected injection drug users
Authors: CARRIERI MARIA PATRIZIA , TAMALET CATHERINE , VLAHOV DAVID , YAHI NOUARA , CHESNEY MARGARET , MOATTI JEAN PAUL 
Published: July 2002

AbstractThe role of continued drug use in development of AIDS has been investigated, using mainly CD4+ cells as outcome variable. The objective of this study was to verify whether continued drug use can influence HIV‐1 plasma viral load.We used cross‐sectional enrolment data of the HIV‐infected IDUs cohort study Manif 2000 (October 1995‐October 1996), recruiting patients in hospital departments of Marseilles, Nice and Paris suburbs. To minimize biases due to differential access to health care, only patients receiving outpatient care for at least 2 years but with no antiretroviral treatment were selected for analysis (n = 108). Available information regarding clinical and laboratory information from medical records and clinical examination as well as drug use and HIV‐related risk practices were obtained by a face‐to‐face and a self‐administered questionnaire. Patients denying recent heroin injection were cross‐validated by a serological assay to detect morphine. Forty‐two patients (39%) reported recent heroin injection; among those denying recent use (n=66), eight (positive for serum morphine assay) were re‐classified as IDUs. A difference of 0.35 log in viral load was observed between active and ex‐IDUs which increases (0.6 log, p=0.03) in those who have been using drugs for 10 years or more.This result persisted when adjusted for CD4+ counts, clinical stage or years since diagnosis. Continued drug use may have a significant but limited impact on HIV viral load only in patients with a longer history of drug use. Consequences of persisting drug use on long‐term progression to AIDS has to be investigated further.
BioABACUS: a database of abbreviations and acronyms in biotechnology and computer science.
Authors: Rimer M , O'Connell M 
Published: July 2002

Abstract
SUMMARY: BioABACUS (Biotechnology AB breviation and A cronym U ncovering Service) a new, searchable, cross-referenced, database of abbreviations and acronyms in biotechnology and computer science is described. AVAILABILITY: BioABACUS is accessible over the World Wide Web at http://www.nmsu.edu/molbio/bioABACUShome.htm. CONTACT: mrimer@nmsu.edu,moconnel@nmsu.edu
STRIRED: graphical analysis of string repeats.
Authors: Iazzetti G , Chiusano M L , Calogero R A 
Published: July 2002

Abstract
SUMMARY: STRIRED is a toolkit to generate a graphical picture of the distribution of 4- to 6-mer repeats in a set of user-defined nucleic acid sequences. AVAILABILITY: The STRIRED package can be downloaded as self-extracting archive (strired.exe) by anonymous FTP from biol.dgbm.unina.it (143.225.252.1), in the directory /software/win95/STRIRED. CONTACT: calogero@biol.dgbm.unina. it.
DIAMOD: display and modeling of DNA bending.
Authors: Dlakic M , Harrington R E 
Published: July 2002

Abstract
MOTIVATION: DIAMOD (Displayandmodeling ofDNA) was created as a user-friendly software for exploring and better understanding DNA structural variations, particularly DNA bending. It was intended to be as open as possible so that any of the existing or future predictive models can be used with it. RESULTS: DIAMOD features graphic display and interactive manipulation of DNA molecules on the screen. Since it works with di-, tri- or tetranucleotide models supplied as external files of angular parameters, it was recently used to evaluate critically all available predictive models for DNA bending. The program has a unique option to insert bends at defined positions in DNA sequence independently of the currently used model, which enables the simulation of both intrinsic and protein-induced kinking. Finally, many output file formats facilitate the sharing of data with other programs and the creation of visually pleasing images. AVAILABILITY: The program is available on request to academic users free of charge. It will be distributed via the WWW (http://www-personal.umich.edu/ mensur/software.html). Users with no network access can get a copy directly from the author. CONTACT: mensur@umich.edu
Optimization of ribosomal RNA profile alignments.
Authors: O'Brien E A , Notredame C , Higgins D G 
Published: July 2002

Abstract
MOTIVATION: Large alignments of ribosomal RNA sequences are maintained at various sites. New sequences are added to these alignments using a combination of manual and automatic methods. We examine the use of profile alignment methods for rRNA alignment and try to optimize the choice of parameters and sequence weights. RESULTS: Using a large alignment of eukaryotic SSU rRNA sequences as a test case, we empirically compared the performance of various sequence weighting schemes over a range of gap penalties. We developed a new weighting scheme which gives most weight to the sequences in the profile that are most similar to the new sequence. We show that it gives the most accurate alignments when combined with a more traditional sequence weighting scheme. AVAILABILITY: The source code of all software is freely available by anonymous ftp from chah.ucc.ie in the directory /home/ftp/pub/emmet,in the compressed file PRNAA.tar: CONTACT: emmet@chah.ucc.ie, des@chah.ucc.ie
The new Virgil database: a service of rich links.
Authors: Achard F , Cussat-Blanc C , Viara E , Barillot E 
Published: July 2002

Abstract
MOTIVATION: Links between biological objects are frequently used by researchers in biology. However, many of the links found in public databases are insufficiently documented and difficult to retrieve. Virgil introduces the idea of a rich link, i.e. the link itself and the related pieces of information. Virgil was developed to collect, manage and distribute such links. RESULTS: At the moment, Virgil is a prototype database that contains rich links between GDB genes and Genbank sequences. The Virgil data model is rich enough to describe comprehensively a link between two biological objects. Two different means to access the information were developed: a schema-driven Web interface and a CORBA server. AVAILABILITY: http://www.infobiogen. fr/services/virgil/home.html CONTACT: Frederic.Achard@infobiogen.fr
Molecules to maps: tools for visualization and interaction in support of computational biology.
Authors: Kraemer E T , Ferrin T E 
Published: July 2002

Abstract
The volume of data produced by genome projects, X-ray crystallography, NMR spectroscopy, and electron and confocal microscopy present the bioinformatics community with new challenges for analyzing, understanding, and exchanging this data. At the 1998 Pacific Symposium on Biocomputing, a track entitled 'Molecules to Maps: Tools for Visualization and Interaction in Computational Biology' provided tool developers and users with the opportunity to discuss advances in tools and techniques to assist scientists in evaluating, absorbing, navigating, and correlating this sea of information, through visualization and user interaction. In this paper we present these advances and discuss some of the challenges that remain to be solved.
Genetic Simulation Library.
Authors: Conery J , Lynch M 
Published: July 2002

Abstract
SUMMARY: The Genetic Simulation Library (GSL) is a set of C++ programs and classes that can be used in individual-based simulation models of plant and animal populations. The classes in this library build representations of genes for a wide variety of different types of organisms, from asexually reproducing single-cell organisms to chromosome-structured sexually reproducing species. AVAILABILITY: http://www.csi.uoregon.edu/projects/genetics/GSL . Free for non-commercial applications; others should contact the author.
bioWidgets: data interaction components for genomics.
Authors: Fischer S , Crabtree J , Brunk B , Gibson M , Overton G C 
Published: July 2002

Abstract
MOTIVATION: The presentation of genomics data in a perspicuous visual format is critical for its rapid interpretation and validation. Relatively few public database developers have the resources to implement sophisticated front-end user interfaces themselves. Accordingly, these developers would benefit from a reusable toolkit of user interface and data visualization components. RESULTS: We have designed the bioWidget toolkit as a set of JavaBean components. It includes a wide array of user interface components and defines an architecture for assembling applications. The toolkit is founded on established software engineering design patterns and principles, including componentry, Model-View-Controller, factored models and schema neutrality. As a proof of concept, we have used the bioWidget toolkit to create three extendible applications: AnnotView, BlastView and AlignView.
DINAMO: interactive protein alignment and model building.
Authors: Bentz J , Baucom A , Hansen M , Gregoret L 
Published: July 2002

Abstract
MOTIVATION: To facilitate the process of structure prediction by both comparative modeling and fold recognition, we describe DINAMO, an interactive protein alignment building and model evaluation tool that dynamically couples a multiple sequence alignment editor to a molecular graphics display. DINAMO allows the user to optimize the alignment and model to satisfy the known heuristics of protein structure by means of a set of analysis tools. The analysis tools return information to both the alignment editor and graphics model in the form of visual cues (color, shape), allowing for rapid evaluation. Several analysis tools may be employed, including residue conservation, residue properties (charge, hydrophobicity, volume), residue environmental preference, and secondary structure propensity. RESULTS: We demonstrate DINAMO by building a model for submission in the 3rd annual Critical Assessment of Techniques for Protein Structure Prediction (CASP3) contest. AVAILABILITY: DINAMO is freely available as a local application or Web-based Java applet at http://tito.ucsc.edu/dinamo