cssi/SciSciGPT-SciSciNet huggingface dataset:
Etched-and-Regrown GaN pn -Diodes With 1600 V Blocking Voltage

Etched-and-regrown GaN pn-diodes capable of high breakdown voltage (1610 V), low reverse current leakage (1 nA = 6 $\mu \text{A}$ /cm2 at 1250 V), excellent forward characteristics (ideality factor ~1.6), and low specific on-resistance (1.1 $\text{m}\Omega $ .cm2) were realized by mitigating plasma etch-related defects at the regrown interface. Epitaxial ${n}$ -GaN layers grown by metal-organic chemical vapor deposition on free-standing GaN substrates were etched using inductively coupled plasma etching (ICP), and we demonstrate that a slow reactive ion etch (RIE) prior to ${p}$ -GaN regrowth dramatically increases diode electrical performance compared to wet chemical surface treatments. Etched-and-regrown diodes without a junction termination extension (JTE) were characterized to compare diode performance using the post-ICP RIE method with prior studies of other post-ICP treatments. Then, etched-and-regrown diodes using the post-ICP RIE etch steps prior to regrowth were fabricated with a multi-step JTE to demonstrate kV-class operation.
Wavevector-space metasurface

We discuss meta-surfaces for which the transfer function is diagonal in the waveevector space. We show that such meta-surfaces can be used to perform spatial differentiation, squeeze free space, and generate a variety of optical beams with non-trivial properties associated with orbital or spin angular momentum of light.
A Construct That Obstructs: the Church Parties Model of Sixteenth-Century Russian Church Relations

The dominant construct to explain early sixteenth-century internal Russian Church relations was for over a hundred years one of conflict between two parties – the Possessors (a.k.a. Josephians) and the Non-Possessors (a.k.a. Trans-Volga Elders). Source-based research challenged that conflict model by demonstrating that Iosif Volotskii, the presumed leader of the Possessors, and Nil Sorskii, the presumed leader of the Non-Possessors, and their disciples and followers were not antagonists but collaborators with each other. Nonetheless, the Church parties model has continued being used to explain Russian Church relations for the mid-sixteenth-century. Yet, it is just as faulty to explain the evidence of mid-century as it is for earlier. Evidence, instead of being analyzed, is shoehorned to fit the model. The Church parties-in-conflict model is a historiographical construct that obstructs rather than informs understanding the source testimony. That testimony is far more complex and nuanced than the simplistic Church parties model allows for.
Large-scale design optimisation of boiling water reactor bundles with neuroevolution

Abstract We combine advances in deep reinforcement learning (RL) with evolutionary computation to perform large-scale optimisation of boiling water reactor (BWR) bundles using CASMO4/SIMULATE3 codes; capturing fine details, radial/axial fuel heterogeneity, and real-world constraints. RL constructs neural networks that learn how to assign fuel and poison enrichment by narrowing the search space into the areas where human/physics knowledge demonstrate merit. Evolution strategies diversify the search in these areas, through obtaining guidance from RL candidates. With very efficient/parallel implementation, our optimisation approach is able to solve a coupled multi-zone BWR bundle optimisation with ~ 40 constraints. The methodology is applied to a GE14-10×10 bundle, showing the ability of neuroevolution to find ~ 100 feasible designs. The optimal bundle has 7 axial zones with non-uniform enrichment radially and axially. The results of this work also demonstrate that our neuroevolution methodology is sufficiently generic to adapt to other assembly and reactor designs with minor adjustments.
Parasitic cowbird development up to fledging and subsequent post-fledging survival reflect life history variation found across host species

Generalist avian brood parasites commonly serve as a model system to test for plasticity in offspring growth and behavior under various host environmental and parental regimes. While past research has provided compelling evidence that developmental rates differ among hosts, the fitness consequences of such variation remain unclear. In hosts, carryover effects from the nesting to the post-fledging stage are critical in driving differential post-fledging survival within and among species, as well as the evolution of songbird life histories. Consequently, offspring of brood parasites may be subject to the same carryover effects and life history constraints observed in host species. Applying a pre- to post-fledging carryover effect framework to avian brood parasites may therefore provide novel insights into parasite life histories as well as parasite-host interactions. We assessed the potential influence of host carryover effects on the development and survival of juvenile cowbirds using empirical data from 10 realized host species in east-central Illinois, USA. We found that life history variation among juvenile cowbirds reflects variation in tradeoffs between mortality risk and nestling period length as well as pre- to post-fledging carryover effects found across host species. Cowbirds from host nests with higher mortality rates had shorter nestling periods, fledged with less developed wings, and exhibited higher rates of post-fledging mortality. Cowbird mass at fledging also predicted post-fledging survival, but was not associated with other life history traits. Our results provide novel links between juvenile growth, development, and mortality that help to explain differential survival in parasitic young across host species. Offspring of avian brood parasites develop at different rates based on the host environment in which they are raised, but the fitness consequences of such plasticity are poorly understood. Parasitic offspring may be subject to carryover effects from the nesting to the post-fledging stages and other life history constraints operating in host systems. We assessed the potential influence of host carryover effects on the development and survival of juvenile brown-headed cowbirds (Molothrus ater) using empirical data from 10 realized host species. Reflecting pre- to post-fledging carryover effects found across host species, cowbirds from host nests with higher mortality rates had shorter nestling periods, fledged with less developed wings, and exhibited higher rates of post-fledging mortality. Our results provide novel links between juvenile growth, development, and mortality that help to explain differential survival in parasitic young across host species.
Uncertainty and precaution in hunting wolves twice in a year

When humanity confronts the risk of extinction of species, many people invoke precautions, especially in the face of uncertainty. Although precautionary approaches are value judgments, the timing and effect of precautions or lack thereof are scientific questions. We investigated the Wisconsin gray wolves Canis lupus facing a second wolf-hunt in November 2021 and use three legal thresholds as the societal value judgments about precautions: (1) the 1999 population goal, 350 wolves, (2) the threshold for statutory listing under the state threatened and endangered species act, 250 wolves; and (3) state extirpation
The impact of nonresponse in different survey stages on the precision of prevalence estimates for multi-stage survey studies.

Objective While it is known that nonresponse might produce biased results and impair the precision of results in survey research studies, the pattern of the impact on the precision of estimates due to the nonresponse in different survey stages is historically overlooked. Having this type of information is essential when creating recruitment plans. This study proposes to examine and compare the effect of nonresponse in different stages on the precision of prevalence estimates in multi-stage survey studies. Based on data from a state level survey, a simulation approach was used to generate datasets with different nonresponse rates in three stages. The margin of error was then compared between the datasets with nonresponse at three different survey stages for 12 outcomes. Results At the same nonresponse rate, the mean margin of error was greater for the data with nonresponse at higher stages. Additionally, as the nonresponse rate increased, precision was more inflated within the data with higher stage nonresponse. This suggests that the effort used to recruit the primary sampling units is more crucial to improve the precision of estimates in multi-stage survey studies.
Analysis of web page complexity through visual segmentation

Web pages have increasingly been used as the user interface of many software systems. The simplicity of interaction with web pages is a desirable advantage of using them. However, the user interface can also get more complex when more complex web pages are used to build it. Understanding the complexity of web pages as perceived subjectively by users is therefore important to better design this type of user interface. This paper reports an analysis of web page complexity through visual segmentation of web pages. 100 web pages were visually segmented by human participants as well as a computer program using Gestalt principles. The participants also indicated the perceived complexity of the web pages during the experiment. The result shows the perception of complexity is highly subjective but may be reliably measured. The number of blocks resulted from the three segmentation methods seemed to be irrelevant to perceived complexity. However, a composite metric that incorporate visual block information and other data of web pages seems to be promising in predicting the perceived complexity.
Prematurity--the epidemiologic profile of the "high risk" mother.

Abstract 1. 1. At the Jackson Memorial Hospital, Miami, Florida, the prematurity rate is consistently about twice as high among the staff (indigent) patients as among private patients. 2. 2. An epidemiologic analysis of the indigent group further revealed the patient most likely to have a premature baby within the group. 3. 3. It is suggested that careful scrutiny of these “high risk” patients and their comparison with “low risk” patients in the same socioeconomic group would shed further light on the etiology of premature labor.
Globalization and Austerity Politics in Latin America

1. Introduction 2. Globalization and austerity politics 3. The political economy of elections 4. The electoral boom-bust cycle 5. From gunboat to trading-floor diplomacy 6. When Latin American grasshoppers become ants 7. The political austerity cycle 8. Conclusion Appendix: field research interviews.
Competition Among Aquatic Organisms

Competition is a major organizing force in aquatic communities. Theory as well as laboratory and field studies show that competition is both common and important in inland waters. Aquatic organisms experience both intraspecific and interspecific competition and compete by both exploitative competition (sharing a scarce resource) and interference competition (aggressive interactions). Competitive interactions depend on factors such as ecosystem productivity, the timing of life history features among competing species, the ratio at which limiting resources are supplied and used, and temporal variability in resource supply. Competition among aquatic organisms depends on the size structure of populations of competing species. Also, competition occurs within complex food webs in which the presence of other species, especially predators, can affect competitive interactions. Ecologists continue to unravel the means by which competition affects aquatic communities; future studies can be expected to elucidate the importance of competition to environmental problems such as those associated with the spread of invasive species, the ecology of infectious disease, and the conservation of biodiversity.
Ford Speed Control Utilizes I2L Technology

A new Ford speed control amplifier has been designed using an I 2L custom integrated circuit (IC) which was independently designed by multiple vendors from functional block diagrams, which included definition of all external components and characterization of all inputs and outputs. The IC's contain both analog and digital functions on a single substate. The designs have resulted in a speed control amplifier providing more features, reduced package size, and lower warranty return projections than the previous design.
Effects of BPA and BPS exposure limited to early embryogenesis persist to impair non-associative learning in adults

Background Bisphenol-A (BPA) is a polymerizing agent used in plastic bottles and several routinely used consumer items. It is classified among endocrine disrupting chemicals suspected to cause adverse health effects in mammals ranging from infertility and cancer to behavioral disorders. Work with the invertebrate lab model Caenorhabditis elegans has shown that BPA affects germ cells by disrupting double-stranded DNA break repair mechanisms. The current study utilizes this model organism to provide insight into low-dose and long-term behavioral effects of BPA and bisphenol-S (BPS), a supposed safer replacement for BPA.
Internationalization and Firm Governance: The Roles of CEO Compensation, Top Team Composition, and Board Structure

Using the complementary lenses of information-processing and agency theories, this study tests the proposition that the complexity resulting from a firm's degree of internationalization will be acc...
Photoluminescence of CdSe with picosecond time resolution

Abstract The temporal evolution of luminescence of CdSe at He-temperature is studied after picosecond-pulse photo excitation with a Kerr shutter technique capable of 15 psec resolution.
Analysis of centrifugal convection in rotating pipes

New exact solutions, obtained for centrifugal convection of a compressible fluid in pipes and annular pipes, explain axially elongated counterflow and energy separation—poorly understood phenomena occurring in vortex devices, e.g., hydrocyclones and Ranque tubes. Centrifugal acceleration (which can be up to 106 times gravity in practical vortex tubes), combined with an axial gradient of temperature (even small), induces an intense flow from the cold end to the hot end along the pipe wall and a backflow near the axis. To account for large density variations in vortex devices, we use the axial temperature gradient as a small parameter instead of the Boussinesq approximation. For weak pipe rotation, the swirl is of solid-body type and solutions are compact: vz/vza=1−4y2+3y4 and (T−Tw)/(Ta−Tw)=(1−y2)3; where y=r/rw, the subscripts w and a denote values of axial velocity vz, temperature T, and radial distance r, at the wall and on the axis. The axial gradient of pressure, being proportional to 3y2−1, has oppos...
Technological Innovation as a Gateway to Entry: The Case of the Telecommunications Equipment Industry

This study first reviews the concept of entry barriers in the economics and strategic management literature and investment in innovation as a particular kind of barrier to entry. An argument is then presented that one can also view, from the perspective of the entrant, innovation as a gateway into a changing industry. Data from the telecommunications equipment industry during the period 1975–1986 support this argument. These findings suggest that the traditional, steadystate assumptions underlying the industrial organization paradigm, and the recently developed strategy typologies based on this paradigm, may be inappropriate in industries experiencing fundamental technological changes. In such cases, strategies designed to take advantage of change may be more fruitful.
The Graduate School Application Process: What Our Students Report They Know

One hundred and thirty-four undergraduate psychology majors completed a survey assessing their evaluative ratings of importance of factors related to the graduate school application process. Result...
Alternative Markov Properties for Chain Graphs

Graphical Markov models use graphs to represent possible dependences among statistical variables. Lauritzen, Wermuth, and Frydenberg (LWF) introduced a Markov property for chain graphs (CG): graphs that can be used to represent both structural and associative dependences simultaneously and that include both undirected graphs (UG) and acyclic directed graphs (ADG) as special cases. Here an alternative Markov property (AMP) for CGs is introduced and shown to be the Markov property satisfied by a block-recursive linear system with multivariate normal errors. This model can be decomposed into a collection of conditional normal models, each of which combines the features of multivariate linear regression models and covariance selection models, facilitating the estimation of its parameters. In the general case, necessary and sufficient conditions are given for the equivalence of the LWF and AMP Markov properties of a CG, for the AMP Markov equivalence of two CGs, for the AMP Markov equivalence of a CG to some ADG or decomposable UG, and for other equivalences. For CGs, in some ways the AMP property is a more direct extension of the ADG Markov property than is the LWF property.
An evaluation of the assumptions that underlie institutional anomie theory

Messner and Rosenfeld's institutional anomie theory [IAT] postulates that a pervasive cultural mandate to obtain material wealth, coupled with an anomic normative environment that arises from a pro...
Comparison of MEGX (monoethylglycinexylidide) and antipyrine tests in patients with liver cirrhosis

The aim of the study was to compare the feasibility of the MEGX (monoethylglycinexylidide) and antipyrine tests in reference to standard biochemical parameters used for liver assessment in cirrhotic patients. The study was carried out in 44 subjects: 14 healthy controls and 30 cirrhotic patients classified according to the Child-Pugh’s score to subgroups A (n=11), B (n=12) and C (n=7). All subjects underwent two dynamic liver tests, i.e. MEGX (monoethylglycinexylidide) and antipyrine test in a crossover schedule with at least 5-day interval. For the MEGX, lidocaine was administrated intravenously, at a dose of 1 mg/kg, and blood samples for MEGX assay were collected after 15 minutes. MEGX concentrations were measured by fluorescence polarization immunoassay. The antipyrine concentrations were evaluated following a single oral administration of 1000 mg antipyrine. The blood was sampled for 24 hours after the drug administration, and antipyrine concentrations were measured spectrophotometrically. Standard biochemical parameters used for liver assessment were measured by means of routine laboratory methods. It was concluded that in patients liver with cirrhosis, liver dynamic tests were better predictors of hepatic function. The MEGX test was more feasible in clinical setting, but it was noted that antipyrine test was more sensitive in staging liver cirrhosis.
La invención del desarrollo en Colombia

• Resumen: Existe un espacio comun de reflexion sobre la realidad de los llamados paises del Tercer Mundo, formado por las conceptualizaciones, practicas, programas, planes y estrategias a ser aplicadas en estos paises para elevar su nivel de desarrollo economico y social. Este articulo relaciona la aparicion y progresiva consolidacion de esta reflexion sobre dichas sociedades con la evolucion de la politica y la economia mundiales en los ultimos decenios y propone mirar el discurso del desarrollo como una entidad en la que el poder y el conocimiento se articulan para servir como tecnologia politica, cuyo proposito es el manejo y la creacion sistematica del Tercer Mundo como realidad historica. El analisis esta centrado en el caso de Colombia, destacando ademas la contribucion a esta linea investigativa del sociologo colombiano Orlando Fals Borda, especialmente con su ultima obra: Historia doble de la Costa. • Abstract: A common set of concepts provides the framework for much of the discussion of Latin American economic reality. These are expressed in the various practices, plans, programs and strategies which have addressed questions of economic and social development. This paper relates the evolution of this set of concepts to global political and economic development over recent decades. It considers the discourse about development as an element of power and knowledge which serves an important function in the systematic creation of the Third World. The analysis centers on Colombia and supersedes other contributions based on this methodology such as Orlando Fals Borda's Historia doble de la Costa.
Laboratory and Field Evaluation of Cement-Treated Reclaimed Asphalt Pavement Blends as Roadway Base Material

Reclaimed asphalt pavement (RAP) and granular base materials were collected throughout Texas to evaluate the properties of RAP and RAP blended with virgin or salvage aggregates for roadway base course application. Mixes containing RAP of 100 %, 75 %, and 50 % and treated with Portland cement of different dosages were utilized in a comprehensive laboratory testing program. The factors that affect the properties of cement-treated RAP mixes are identified and a mix design model based on typical RAP and granular base materials in Texas was proposed. The design model was verified by the data from the initial field trial on actual construction projects. The feasibility of using a modulus-based procedure for quality assurance/quality control during construction is discussed.
Umbelactonyl cinnamate derivatives from Crypteronia paniculata that mediate DNA strand scission.

As part of an initiative to discover functional natural product analogues of bleomycin guided by the use of the COMPARE algorithm, a CH2Cl2−MeOH extract prepared from Crypteronia paniculata was found to exhibit relaxation of supercoiled pSP64 DNA in the presence of Cu2+. Bioassay-guided fractionation employing a DNA strand scission assay resulted in the isolation of three novel DNA cleavage agents. Their structures were elucidated as umbelactonyl cinnamate derivatives 1−3 through their NMR and MS spectral data analyses. This is the first example of the isolation and structural characterization of naturally occurring umbelactonyl cinnamate derivatives. Compound 1 exhibited strong Cu2+-dependent relaxation of supercoiled pSP64 DNA, while compounds 2 and 3 had only weak DNA cleavage activity.
Ultra-high efficiency multilayer blazed gratings through deposition kinetic control

Diffraction efficiency of multilayer-coated blazed gratings (MBG) strongly depends on the perfection of the sawtooth-shaped layers in the overall composite structure. Growth of multilayers on sawtooth substrates should be carefully optimized to reduce groove profile distortion and, at the same time, to avoid significant roughening of multilayer interfaces. In this work, we report on a way to optimize growth of sputter-deposited Mo/Si multilayers on sawtooth substrates through variation of the sputtering gas pressure. We believe a new record for diffraction efficiency of 44% was achieved for an optimized MBG with groove density of 5250 lines/mm at the wavelength of 13.1 nm.
Returning students' right to access, choice and notice: a proposed code of ethics for instructors using Turnitin

This paper identifies the ethical issues associated with college instructors' use of plagiarism detection software (PDS), specifically the Turnitin program. It addresses the pros and cons of using such software in higher education, arguing that its use is justified on the basis that it increases institutional trust, and demonstrating that two common criticisms of such software are not universally valid. An analysis of the legal issues surrounding Turnitin, however, indicates that the way it is designed and operates raises some ethical issues because it denies students notice, access and choice about the treatment of their personal information. The paper concludes with a set of guidelines for instructors using Turnitin in the classroom.
A randomized Delaunay triangulation heuristic for the Euclidean Steiner tree problem in R d

We present a heuristic for the Euclidean Steiner tree problem in R d for d≥2. The algorithm utilizes the Delaunay triangulation to generate candidate Steiner points for insertion, the minimum spanning tree to identify the Steiner points to remove, and second-order cone programming to optimize the location of the remaining Steiner points. Unlike other ESTP heuristics relying upon Delaunay triangulation, we insert Steiner points probabilistically into Delaunay triangles to achieve different subtrees on subsets of terminal points. We govern this neighbor generation procedure with a local search framework that extends effectively into higher dimensions. We present computational results on benchmark test problems in R d for 2≤d≤5.
A magnetospheric specification model validation study: Geosynchronous electrons

Abstract The Rice University Magnetospheric Specification Model (MSM) is an operational space environment model of the inner and middle magnetosphere designed to specify charged particle fluxes up to 100 keV. Validation test data taken between January 1996 and June 1998 consist of electron fluxes measured by a charge control system (CCS) on a defense satellite communications system (DSCS) spacecraft. The CCS includes both electrostatic analyzers to measure the particle environment and surface potential monitors to track differential charging between various materials and vehicle ground. While typical RMS error analysis methods provide a sense of the models overall abilities, they do not specifically address physical situations critical to operations, i.e., how well does the model specify when a high differential charging state is probable. In this validation study, differential charging states observed by DSCS are used to determine several threshold fluxes for the associated 20–50 keV electrons and joint probability distributions are constructed to determine Hit, Miss, and False Alarm rates for the models. An MSM run covering the two and one-half year interval is performed using the minimum required input parameter set, consisting of only the magnetic activity index Kp , in order to statistically examine the model's seasonal and yearly performance. In addition, the relative merits of the input parameter, i.e., Kp , Dst , the equatorward boundary of diffuse aurora at midnight, cross-polar cap potential, solar wind density and velocity, and interplanetary magnetic field values, are evaluated as drivers of shorter model runs of 100 d each. In an effort to develop operational tools that can address spacecraft charging issues, we also identify temporal features in the model output that can be directly linked to input parameter variations and model boundary conditions. All model output is interpreted using the full three-dimensional, dipole tilt-dependent algorithms currently in operational use at the Air Force 55th Space Weather Squadron (55 SWXS). Results indicate that both diurnal and seasonal activity related variations in geosynchronous electrons are reproduced in a regular and consistent manner regardless of the input parameter used as drivers. The ability of the MSM to specify DSCS electrons in relation to thresholds indicative of spacecraft charging varies with the combination of input parameters used. The input parameter of greatest benefit to the MSM, after the required Kp index, is the polar cap potential drop as determined by DMSP spacecraft. Regarding the highest electron flux threshold, the model typically achieves high HIT rates paired with both high False Alarm rates and higher RMS error. Suggestions are made regarding the utilization of proxy values for the polar cap potential parameter and Kp -dependent model boundary conditions. The importance of generating accurate real-time proxy input data for operational use is stressed.
Prognostic indicators for successful vaginal birth after cesarean delivery

Abstract Objective: To determine characteristics associated with successful trials of labor after cesarean delivery (TOLAC) and to determine the success of vaginal birth after cesarean delivery (VBAC) in a subset of patients with previous cesarean delivery for failure to progress at full dilatation. Methods: A retrospective chart review from January 1997 through April 1998 of patients undergoing TOLAC at our institution. Four hundred forty-four charts met the inclusion criteria. Statistics were analyzed using the χ 2 test and the Fisher’s exact test (2-tail). Results: The following characteristics were found to be statistically significant positive prognostic indicators: history of prior vaginal delivery ( P = 2.05E-5); spontaneous rather than induced labor ( P = 0.0001); greater dilation ( P = 1.22E-6); and greater effacement ( P = 0.001). Heavier women were less successful ( P = 0.004); and use of a ripening agent led to a decreased rate of success ( P = 0.016). In women previously undergoing cesarean delivery for arrest of descent at full dilatation, 74.5% ( P = 2.0E-4) delivered vaginally. The operative vaginal delivery rate was 40% in this subgroup. Conclusions: Lower maternal weight at delivery, history of prior vaginal delivery, spontaneous labor, lack of need for ripening agents, and greater dilatation and effacement on admission correlated with successful VBAC. Three quarters of women with a prior cesarean delivery for arrest of descent at full dilatation delivered vaginally. This is in marked contrast to prior literature, which reported success rates of 16% or less in these patients. This subset of patients had a 40% operative delivery rate, as opposed to 11.8% of patients in the general population at our center. This stresses the importance of maintaining skills in the art of operative vaginal delivery.
What Sternberg should have concluded

This article responds to issues raised by Professor Sternberg in response to my article analyzing the Sternberg Triarchic Abilities Test (STAT). First, I respond to specific issues he considers in his article dealing with corrections of obtained correlations and interpretations of method variance in STAT. Second, I present a synopsis of what I take to be the appropriate conclusions that should have been derived from the data obtained by Professor Sternberg and his colleagues assessing the construct validity of STAT. Third, I provide a brief conclusion for the article.
High-efficiency resonance ionization mass spectrometric analysis by external laser cavity enhancement techniques

A novel electronic circuit has been developed that detects absorption in one of two (reference and signal) laser beams with shot noise-limited sensitivity. The authors demonstrate its use as a simple shot noise limited spectroscopy by measuring several absorption lines of I2 vapor near 670 nm with a tunable diode laser. The noise-equivalent absorption in this double-beam method is 2 times the shot-noise-to-signal ratio of the signal beam. In this case, for 1.2 mW of power, the noise-equivalent absorption in a 1-Hz bandwidth was 4.2 X 10-8. This noise level was confirmed, although measurements were sometimes limited by interference fringes and laser tuning drift. These are technical, not fundamental, problems arising from unsophisticated optical equipment. This baseband method provides absorption spectra directly, eliminating laser excess noise without the somewhat elaborate signal generation and processing equipment needed in laser frequency modulation methods. The only modulation used in the system was the 0.5 to 1.0-kHz sweep of the diode laser current used to tune the laser output wavelength. The noise-cancelling circuit itself is not complex: workable versions can be constructed from readily available components at a cost of about 10 dollars.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Energy levels, luminescence and electronic structure of ZnS: Tm3+

Abstract Energy levels, densities of states, electronic densities, electrostatic interaction integral parameters F k and spin-orbit coupling parameters ζ 4f for ZnS: Tm 3+ are calculated self-consistently, using both one-electron local density discrete variational non-relativistic Hartree-Fock-Slater (HFS) and relativistic Dirac-Slater (DS) cluster models. In these calculations, both spin-restricted and spin-polarized models are considered. The finite clusters calculated include TmS 4 and TmS 4 Zn 12 clusters for cubic ZnS, which are embedded in the crystal environment. The spin-orbit coupling parameter ζ 4f derived from DS cluster calculations is equal to 2689 cm -1 , rather near the result of the relativistic Hartree-Fock free ion model. The parameters F k and ζ 4f are further calculated from the 4f radial wave function obtained by solving the HFS and the DS atomic equations. It is shown that by decreasing the effective exchange-correlation potential, these parameters can be reduced to approximately match empirical values. A comparison of the excited energy level scheme of ZnS:Tm derived from the calculated parameters and the experimental spectra is presented.
A general scheme for the analytic decomposition of objective test scores: Illustrative demonstrations using the Rod-and-Frame test and the Müller-Lyer illusion

Abstract Objective tests of personality typically include a number of items or trials; the total score on the test is the sum of the subject's “correct” responses across all such trials. Normally, the trials are varied systematically across various facets of the test design, so that the total score represents a composite measure of accuracy averaged across these test facets. However, since only one score is computed for each subject, some potentially important kinds of individual differences—namely all those associated with each particular variation in the test design—are treated solely as measurement unreliability. Such a psychometric stance may serve to obscure more differentiated types of individual differences, with the result that composite scores from trials based on one type of experimental design may not be highly related to such scores from trials using a somewhat different design. The present paper presents a general procedure for scoring objective tests more analytically. To illustrate this general rationale, and to demonstrate its potential utility, data have been reanalyzed from two previous studies, one using the Rod-and-Frame test, the other the Muller-Lyer illusion. In both cases, the traditional global accuracy score did not correlate significantly with other theoretically related variables, while a number of component scores were quite highly related.
The Effect of Supplemental Calcium and Vitamin D3 on Line and Strain Differences in Egg Shell Strength

Abstract Lines from each of six commercial layer strains previously selected on the basis of relatively good or poor shell strength were either, (1) fed supplemental calcium as oyster shell ad libitum or (2) injected with vitamin D3 (600 I.C.U. in trial 1 and 20,000 I.C.U. in trial 2) or (3) received no supplemental calcium or vitamin D3. Shell strength was measured by shell thickness, specific gravity, deformation and breaking strength on three eggs from each bird at the beginning of the experiment and at weekly intervals for three weeks during each of two trials. Trial 1 was conducted during the twelfth month of lay and Trial 2 during the nineteenth month of lay (six months post-molt). The injection of vitamin D3 did not significantly increase the shell strength of the high and low lines, neither did it alter shell strength differences between different strains. The feeding of additional Ca in the form of oyster shell significantly improved the shell strength by all shell strength measures in Trial 1. In Trial 2, which was conducted post-molt, the shell strength was not significantly improved. Although the additional dietary Ca did not significantly alter strain and line differences in shell strength the rate of increase in shell strength of lines and in the degree of response of some strains to Ca supplementation was observed.
Effect of geometrical and chemical constraints on water flux across artificial membranes.

Studies have been made on the temperature dependence of both the hydraulic conductivity, Lp, and the THO diffusion coefficient, ω, for a series of cellulose acetate membranes (CA) of varying porosity. A similar study was also made of a much less polar cellulose triacetate membrane (CTA). The apparent activation energies, Ea, for diffusion across CA membranes vary with porosity, being 7.8 kcal/mole for the nonporous membrane and 5.5 kcal/mole for the most porous one. Ea for diffusion across the less polar CTA membrane is smaller than Ea for the CA membrane of equivalent porosity. Classical viscous flow, in which the hydraulic conductivity is inversely related to bulk water viscosity, has been demonstrated across membranes with very small equivalent pores. Water-membrane interactions, which depend upon both chemical and geometrical factors are of particular importance in diffusion. The implication of these findings for the interpretation of water permeability experiments across biological membranes is discussed.
Unusual case of recurrent renal artery stenosis: lessons to learn.

Department of Interventional Cardiology and Vascular Medicine, Massachusetts General Hospital, Boston, Massachusetts, USACASE PRESENTATIONA 39 year old male chef with previous right aorto-renalartery surgical reimplantation at age 8 for reportedcongenital renal artery stenosis presented to an outsidehospital with gastroenteritis including symptoms ofabdominal pain, nausea, diarrhea and vomiting. Pastmedical history apart from previous surgery for congenitalrenal artery stenosis was unremarkable. He was an activetobacco user of one pack per day for the previous20 years. There was no family history of prematurecoronary disease. Examination revealed a blood pressureof 210/100 mmHg, heart rate of 88 beats per minute andrespiratory rate of 16 per minute. Blood pressurerecordings were equal in both upper limbs. The radial,brachial, femoral and distal lower limb pulses weresymmetrical and of normal volume. No bruits wereaudible over the carotid, subclavian or femoral arteries.The remainders of the cardiac, respiratory and abdominalexaminations were unremarkable apart from a surgicalscar as a result of previous renal artery surgery.Medications included nifedipine 90mg and enalapril20mg had been started one month earlier for worseninghypertension. Laboratory profile on admission is shown in(Table 1).
Reducing Sedentary Behavior: A New Paradigm in Physical Activity Promotion

There is growing interest in the role of sedentary behavior as a risk factor for poor health, independent of physical activity (PA). To guide the spectrum of descriptive, analytic, and intervention...
Multiple members of the plasminogen-apolipoprotein(a) gene family associated with thrombosis.

Plasminogen and apolipoprotein(a) (apo(a)) are closely related plasma proteins that are associated with hereditary thrombophilia. Low plasminogen levels are found in some patients who developed venous thrombosis, while a population with high plasma concentrations of apo(a) have a higher incidence of arterial thrombosis. Two different gene coding for human apo(a) have been isolated and characterized in order to study and compare these genes with four other closely related genes in the plasminogen-apo(a) gene family. These include the gene coding for plasminogen, two unique plasminogen-related genes, and a gene coding for hepatocyte growth factor. Nucleotide sequence analysis of these genes revealed that the exons and their boundaries of these genes for plasminogen and apo(a), and the plasminogen-related genes, differ only 1-5% in sequence. The types of exon/intron junctions and positions of introns in the molecules are also exactly identical, suggesting that these genes have evolved from an ancestral plasminogen gene via duplication and exon shuffling. By utilizing these results, gene-specific probes have been designed for the analysis of each of the genes in this gene family. The plasminogen and two apo(a) genes were all localized to chromosome 6 by employing the gene-specific primers and genomic DNAs from human-hamster cell hybrids. Thesemore » data also make it possible to characterize the apo(a) and plasminogen genes in individuals by in vitro amplification.« less
Arteriovenous malformation of the mandible: life-threatening complications during tooth extraction

This case illustrates how a vascular malformation can turn an ordinary tooth extraction into an emergency situation. Arteriovenous malformations are rare and difficult to detect on radiographs. Early warning signs are discussed and surgical treatment is described.
Indirect Dissociative Recombination of LiH+ Molecules Fueled by Complex Resonance Manifolds

The molecule is prototypical of the dissociative recombination (DR) process, in which a colliding electron destroys the molecule through Rydberg capture pathways. This Letter develops the first quantitative test of the Siegert state multichannel quantum-defect theory description of indirect DR for a diatomic molecular ion. The -matrix approach is adopted to calculate quantum defects, functions of the internuclear distance that characterize both Rydberg states and the zero-energy collisions of electrons with ions. We identify the doorways to fast indirect DR as complex resonance manifolds, which couple closed channels having both high and low principal quantum numbers. This sheds new light on the competition between direct and indirect DR pathways and suggests the reason previous theory underestimated the DR rate by an order of magnitude.
Laser supraglottoplasty for laryngomalacia: are specific anatomical defects more influential than associated anomalies on outcome?

Objective: To evaluate different CO2 laser procedures on children with various types of laryngomalacia and determine the role of associated anomalies on the outcome. Design: Retrospective chart review. Setting: Academic tertiary referral center. Patients: Twenty-three children who underwent laser supraglottoplasty for laryngomalacia between 1991 and 1998 at the UC Davis Medical Center. Interventions: CO2 laser vaporization of redundant supraglottic mucosa of the aryepiglottic fold, arytenoid, and the epiglottis, or modification of the latter, either individually or in combination, based on the obstructing anatomy. Outcome measures: Immediate, short term, intermediate and long term relief of respiratory symptoms, feeding difficulties, effect of associated anomalies on outcome, effect of specific anatomic obstructing site and surgical procedure performed on outcome, and the incidence of complications inherent to the procedure. Results: Children without associated anomalies invariably did very well, with 78% immediately resolving their respiratory symptoms and 100% within a week. Twelve of the 14 patients with unfavorable immediate results (P<0.01) and all ten with short term unfavorable results (P<0.05) had neurologic or anatomic associated anomalies. Seven patients, all with associated anomalies, were considered surgical failures (P<0.05). These patients also had a significantly longer hospital stay (P<0.01). The presence of associated anomalies was significant (P<0.01) in determining surgical treatment of reflux or the need for an NG tube in treating feeding problems. The anatomic site of abnormality and the specific procedure performed did not affect the outcome. There were no serious complications inherent to this procedure. Conclusions: Laser supraglottoplasty, in its different modalities, is a safe and effective treatment for all types of laryngomalacia, but children with associated neurologic or anatomic anomalies will have a more complicated immediate and short term course, as well as a significant incidence of failure. Gastroesophageal reflux is an important associated condition that requires investigation in these patients, and in severe cases will merit surgical procedures to manage. The high incidence of associated neuromuscular anomalies suggests that this component has an important role in the etiology of laryngomalacia.
Reaction of sodium hydride with boron trichloride to form diborane

Sodium hydride and boron trichloride react to form nearly stoicheiometric amounts of diborane in the presence of anhydrous aluminium chloride and aromatic solvents such as benzene. The sodium chloride by-product, which apparently prevents reaction of sodium hydride if it is not removed from the surface of the hydride, reacts with aluminium chloride and dissolves in benzene. The reaction temperature should be kept below 68° to minimise decomposition of the sodium hydride.
Are There Genuine Physical Explanations of Mathematical Phenomena

AbstractThere are lots of arguments for, or justifications of, mathematical theorems that make use of principles from physics. Do any of these constitute explanations? On the one hand, physical pri...
Synthesis of [3H]-desciclovir, prodrug of the antiviral acyclovir

The title compound was prepared by direct radiochemical synthesis from 2-acetylamino-9-[(2-hydroxyethoxy)methyl]-9H-purine. The product had a specific activity of 21.5 Ci mmol−1 and a radiochemical purity of 99.2%. The general approach described may be applicable to other “acyclic” nucleosides.
Neutron scattering in the plane of membranes: structure of alamethicin pores

A technique of neutron in-plane scattering for studying the structures of peptide pores in membranes is described. Alamethicin in the inserted state was prepared and undeuterated and deuterated dilauroyl phosphatidylcholine (DLPC) hydrated with D2O or H2O. Neutron in-plane scattering showed a strong dependence on deuteration, clearly indicating that water is a part of the high-order structure of inserted alamethicin. The data are consistent with the simple barrel-stave model originally proposed by Baumann and Mueller. The theoretical curves computed with this model at four different deuteration conditions agree with the data in all cases. Both the diameter of the water pore and the effective outside diameter of the channel are determined accurately. Alamethicin forms pores in a narrow range of size. In a given sample condition, > 70% of the peptide forms pores of n and n +/- 1 monomers. The pore size varies with hydration and with lipid. In DLPC, the pores are made of n = 8-9 monomers, with a water pore approximately 18 A in diameter and with an effective outside diameter of approximately 40 A. In diphytanoyl phosphatidylcholine, the pores are made of n approximately 11 monomers, with a water pore approximately 26 A in diameter, with an effective outside diameter of approximately 50 A.
Specific heat of monolayer films of3He-4He mixtures adsorbed on Grafoil between 0.04 and 4.2 K

The specific heat of mixtures of 3He and 4He adsorbed on Grafoil has been measured at four partial monolayer coverages corresponding to areal densities of 0.0279, 0.0419, 0.0485, and 0.066 »−2 for 0.04 < T < 4.2 K. The 3He concentration in the mixtures was x 3 = 0, 0.050, 0.091, 0.201, 0.485, 0.650, 0.908, and 0.999. A feature in the specific heat not seen in measurements with the pure isotopes is found for the two intermediate coverages at about 0.4 K. The measurements are analyzed at the higher temperatures using a theoretical virial expansion for two-dimensional gaseous mixtures. The entropy of mixing calculated by numerical integration of the specific heat curves shows that at 4 K the two isotopes are mixed. While mixing effects develop at temperatures below 1 K, the evidence for phase separation as in bulk mixtures is inconclusive.
Nyquist-rate digital-to-analog converter architectures

This article covers two popular types of Nyquist-rate digital-to-analog converters (DACs): the flash DAC and the serial DAC. Flash DACs perform their conversion in a single clock cycle and are typically designed to operate at high-speeds. Serial DACs convert the digital signal to an analog signal one bit at a time. Serial DACs trade the hardware complexity of a flash DAC for longer conversion times. In this article, three variations of flash DACs are introduced along with two serial DACs. Also the advantages and disadvantages for each architecture are discussed.