cssi/SciSciGPT-SciSciNet huggingface dataset:
The effect of reflecting contacts on high field transport

ABSTRACT There has been considerable recent interest in semiconductor device structures which take advantage of high velocity, high field transport. The high electron velocity in devices that take advantage of such transport is degraded if electrons are reflected at collecting contacts. This was demonstrated quantitatively by Brennan and coworkers (1983) who modeled the collecting contact with a constant, arbitrary reflection coefficient. For a real contact, however, the probability of an electron being reflected depends on its energy and momentum. We present a study of the effect of contacts on high field transport by detailed Monte Carlo simulations of transport in an n- region which terminates in an n GaAs/metal contact (Arnold 1987). The details of the Monte Carlo transport simulation method which we employed were reported by Brennan and coworkers (1983a) and in the references contained therein. The contact is modeled as a thin n+ doped region of GaAs, sandwiched between the active region of the device and a contact metal. The potential was found by solving Poisson's Equation for this system in equilibrium. A voltage drop across the device is is added by assuming a constant applied field in the (n-GaAs) active region. The transmission matrix technique has been used to accurately calculate the reflection probability for energies above and below the maximum of the barrier (Kane 1969). Here the matching conditions for the solution of Schroedingers Equation are continuity of the wavefunction ∂ and of the current, i.e., of (1/m*)(∂ψ/∂x), where m is the energy dependent effective mass.
THE OPTIMAL FORM OF DISTRIBUTION NETWORKS APPLIED TO THE KIDNEY AND LUNG

A model is proposed to minimize the total volume of the main distribution networks of fluids in relation to the organ form. The minimization analysis shows that the overall exterior form of distribution networks is a modified ellipsoid, a geometric form that is a good approximation to the external anatomy of the kidney and lung. The variational procedure implementing this minimization is similar to the traditional isoperimetric theorems of geometry.
Reconstructing DNA copy number by joint segmentation of multiple sequences

Background: Variations in DNA copy number carry information on the modalities of genome evolution and mis-regulation of DNA replication in cancer cells. Their study can help localize tumor suppressor genes, distinguish different populations of cancerous cells, and identify genomic variations responsible for disease phenotypes. A number of different high throughput technologies can be used to identify copy number variable sites, and the literature documents multiple effective algorithms. We focus here on the specific problem of detecting regions where variation in copy number is relatively common in the sample at hand. This problem encompasses the cases of copy number polymorphisms, related samples, technical replicates, and cancerous sub-populations from the same individual. Results: We present a segmentation method named generalized fused lasso (GFL) to reconstruct copy number variant regions. GFL is based on penalized estimation and is capable of processing multiple signals jointly. Our approach is computationally very attractive and leads to sensitivity and specificity levels comparable to those of state-of-the-art specialized methodologies. We illustrate its applicability with simulated and real data sets. Conclusions: The flexibility of our framework makes it applicable to data obtained with a wide range of technology. Its versatility and speed make GFL particularly useful in the initial screening stages of large data sets.
Labor federalism in the United States: lessons for international labor rights

Before the 1960s, United States regulatory institutions effectively enforced the principle that interstate commerce in goods produced in violation of workers' rights of association is an unfair trade practice. Thereafter, the same institutions facilitated the de facto non-enforcement of those core labor rights. This experience is best understood through regulatory models of "coordinated decentralization." The experience of United States labor federalism points to several institutional features that are likely to prove critical to the success or failure of any supranational architecture for enforcement of international labor rights, including: the regulatory endogeneity of interest groups; the structure of non-governmental institutions that span the tiers of federal public institutions; the mechanisms that mutually reinforce procedural and substantive rights of association; and the public-private networks that seek economic growth through agglomeration of human physical capital or, instead, through minimization of unit labor costs.
Charge motion effects in ionic clusters

Abstract In ionic clusters the polarization depends on the dynamics of charge delocalization. The polarization follows the charge motion whe the characteristic time of motion is much longer than the polarization time (adiabatic polarization). For the opposite case (diabatic polarization), the polarization is determined by an average field. These two kinds of polarization are considered for the ionic clusters Xe + 2 R and benzene + -R (RHe, Ne, Ar).
Empirical evidence on the publicness of state legislative activities

Legislation would be a Samuelsonian public good if the cost of creating legislation is not a function of the number of people covered by the legislation. A straighforward test of Samuelsonian publicness is undertaken by estimating the cost of producing legislation as a function of population and other variables, using cross-sectional data from the states of the United States for the years 1965, 1975, and 1985. The empirical results indicate that while legislation does have some degree of publicness, legislation is mostly a private good, and that it has been becoming increasingly less public over time.
Cancer death rates for older Asian-Americans: classification by race versus ethnicity

Objective For most US health statistics, Asian-Americans are grouped into a single race category. We use a unique data file to determine site-specific cancer death rates for persons aged 65 and older in six Asian-American ethnic subgroups (Chinese, Indian, Japanese, Korean, Filipino, and Vietnamese) and determine for which cancer sites the aggregate Asian-American race category is a misleading summary of subgroup cancer risk.
On the Origin of the Type Ia Supernova Width-Luminosity Relation

Brighter Type Ia supernovae (SNe Ia) have broader, more slowly declining B-band light curves than dimmer SNe Ia. We study the physical origin of this width-luminosity relation (WLR) using detailed radiative transfer calculations of Chandrasekhar-mass SN Ia models. We find that the luminosity dependence of the diffusion time (emphasized in previous studies) is in fact of secondary relevance in understanding the model WLR. Instead, the essential physics involves the luminosity dependence of the spectroscopic/color evolution of SNe Ia. Following maximum light, the SN colors are increasingly affected by the development of numerous Fe II/Co II lines that blanket the B band and, at the same time, increase the emissivity at longer wavelengths. Because dimmer SNe Ia are generally cooler, they experience an earlier onset of Fe III to Fe II recombination in the iron group rich layers of ejecta, resulting in a more rapid evolution of the SN colors to the red. The faster B-band decline rate of dimmer SNe Ia thus reflects their faster ionization evolution.
An analogue of the Harer-Zagier formula for unicellular maps on general surfaces

A unicellular map is the embedding of a connected graph in a surface in such a way that the complement of the graph is simply connected. In a famous article, Harer and Zagier established a formula for the generating function of unicellular maps counted according to the number of vertices and edges. The keystone of their approach is a counting formula for unicellular maps on orientable surfaces with n edges, and with vertices colored using every color in [q] (adjacent vertices are authorized to have the same color). We give an analogue of this formula for general (locally orientable) surfaces. Our approach is bijective and is inspired by [email protected]?s proof of the Harer-Zagier formula. We first revisit [email protected]?s proof and twist it into a bijection between unicellular maps on orientable surfaces with vertices colored using every color in [q], and maps with vertex set [q] on orientable surfaces with a marked spanning tree. The bijection immediately implies [email protected]?s formula and a formula by Jackson concerning bipartite unicellular maps. It also shed a new light on constructions by Goulden and Nica, Schaeffer and Vassilieva, and Morales and Vassilieva. We then extend the bijection to general surfaces and obtain a correspondence between unicellular maps on general surfaces with vertices colored using every color in [q], and maps on orientable surfaces with vertex set [q]with a marked planar submap. This correspondence gives an analogue of the Harer-Zagier formula for general surfaces. We also show that this formula implies a recursion formula due to Ledoux for the numbers of unicellular maps with given numbers of vertices and edges.
Thermal emission and absorption of radiation in finite inverted-opal photonic crystals

We study theoretically the optical properties of a finite inverted-opal photonic crystal. The light-matter interaction is strongly affected by the presence of the three-dimensional photonic crystal and the alterations of the light emission and absorption processes can be used to suppress or enhance the thermal emissivity and absorptivity of the dielectric structure. We investigate the influence of the absorption present in the system on the relevant band edge frequencies that control the optical response of the photonic crystal. Our study reveals that the absorption processes cause spectral broadening and shifting of the band edge optical resonances, and determine a strong reduction of the photonic band gap spectral range. Using the angular and spectral dependence of the band edge frequencies for stop bands along different directions, we argue that by matching the blackbody emission spectrum peak with a prescribed maximum of the absorption coefficient, it is possible to achieve an angle-sensitive enhancement of the thermal emission/absorption of radiation. This result opens a way to realize a frequency-sensitive and angle-sensitive photonic crystal absorbers/emitters.
Parametric amplification and oscillation at 36 GHz using a point‐contact Josephson junction

We have observed doubly degenerate parametric amplification and oscillation at 36 GHz from a single point‐contact Josephson junction. The experimental results agree qualitatively with theoretical calculations based on the resistively shunted junction model. The estimated noise temperature of an amplifier with 11 dB net gain is consistent with zero, but has an upper limit of 50 K. Attempts to observe parametric amplification in the singly degenerate mode with a pump frequency of 72 GHz were not successful.
BETTI NUMBERS AND DEGREE BOUNDS FOR SOME LINKED ZERO-SCHEMES

In (8), Herzog and Srinivasan study the relationship between the graded Betti numbers of a homogeneous ideal I in a polynomial ring R and the degree of I. For certain classes of ideals, they prove a bound on the degree in terms of the largest and smallest Betti numbers, generalizing results of Huneke and Miller in (9). The bound is conjectured to hold in general; we study this using linkage. If R/I is Cohen-Macaulay, we may reduce to the case where I defines a zero-dimensional subscheme Y. If Y is residual to a zero-scheme Z of a certain type (low degree or points in special position), then we show that the conjecture is true for IY .
Oblique detonation wave engine performance prediction

The performance of an oblique detonation wave engine (ODWE) is evaluated and compared to a diffusive scramjet engine. Diffusive scramjet performance is predicted for both constant area and constant pressure combustion. Detonation wave calculations that utilize a perfect gas approximation vs a real gas model indicate the inadequacy of a perfect gas approach. Hence, a real gas model is utilized hi which the flow is in chemical equilibrium after combustion. Results are provided for both frozen and equilibrium flow through the expansion waves and nozzle. Performance parameters are calculated for H2 and CHi, a range of freestream Mach numbers and fuel flow rates, various inlet configurations, and altitude. Results are for specific thrust and a normalized transverse engine size. The ODWE analysis shows the importance of including the Taylor wave, done here for the first time. An ODWE gives comparable performance to diffusive engines and offers several advantages. The smaller longitudinal size of the ODWE produces less drag and less engine heat transfer. The ODWE offers design flexibility, since the wedge angle that controls the detonation wave can be varied to provide optimum performance over the hypersonic flight envelope. Wedge angle variation also allows for an easy start and restart capability. Nomenclature A = area a = speed of sound 7sp = specific impulse / = length M = Mach number m - mass flow rate p - pressure q = normalized heat addition #00 = dynamic pressure R = specific gas constant T = temperature T = thrust V = flow speed j8 = shock angle j8wlgn = minimum shock angle for ignition y = specific heat ratio 0 = flow turn angle p = density = equivalence ratio
Minimizers of convex functionals arising in random surfaces

We investigate C1-regularity of minimizers to ∫F(∇u)dx in two dimensions for certain classes of nonsmooth convex functionals F. In particular, our results apply to the surface tensions that appear in recent works on random surfaces and random tilings of Kenyon, Okounkov, and others
Cesium Sorption Reactions as Indicator of Clay Mineral Structures

At low cesium ion concentrations extremely high selectivities for cesium are exhibited by layer lattice silicates with unexpanded 10 A c-spacing. The total amount of cesium which can be sorbed by these minerals depends on the edge area and the exchange capacity. At a concentration of 10−5 meq of cesium and 5 meq of sodium, a sample of biotite representing less than 0.025 meq of exchange capacity sorbed over 90 per cent of the cesium and a hydrobiotite with 50 percent vermiculite and representing 1.0 meq of exchange capacity sorbed 80 percent of the cesium.
Rational expectations modeling with seasonally adjusted data

Abstract In a world where time series show clear seasonal fluctuations, rational agents will take account of those fluctuations in planning their own behavior. Using seasonally adjusted data to model behavior of such agents throws away information and introduces possibly severe bias. Nonetheless it may be true fairly often that rational expectations modeling with seasonally adjusted data, treating the adjusted data as if it were actual data, gives approximately correct results; and naive extensions of standard modeling techniques to seasonally unadjusted data may give worse results than naive use of adjusted data. This paper justifies these claims with examples and detailed arguments.
Genetic Algorithms Applied to Multi-Objective Aerodynamic Shape Optimization

A genetic algorithm approach suitable for solving multi-objective problems is described and evaluated using a series of aerodynamic shape optimization problems. Several new features including two variations of a binning selection algorithm and a gene-space transformation procedure are included. The genetic algorithm is suitable for finding Pareto optimal solutions in search spaces that are defined by any number of genes and that contain any number of local extrema. A new masking array capability is included allowing any gene or gene subset to be eliminated as decision variables from the design space. This allows determination of the effect of a single gene or gene subset on the Pareto optimal solution. Results indicate that the genetic algorithm optimization approach is flexible in application and reliable. The binning selection algorithms generally provide Pareto front quality enhancements and moderate convergence efficiency improvements for most of the problems solved.
Deviant generations, Ricardian equivalence, and growth cycles

Two equilibrium possibilities are known to obtain in a standard overlapping-generations model with dynastic preferences: either the altruistic bequest motive is operative for every generation (in which case, Ricardian equivalence obtains) or it is not, for any generation. Dynamic equilibria, where the bequest motive is occasionally operative, cannot emerge. This paper studies bequest-giving behavior and out-of-steady-state bequest and growth dynamics in a Ak model with intra- and inter-generational consumption externalities. These externalities, by their very presence, do not destroy Ricardian equivalence. They may, however, give rise to deviant generations—generations that do not leave a bequest having received an inheritance, and vice versa—and that seals the fate for Ricardian equivalence. Consumption externalities may also generate interesting indeterminacies and endogenous growth cycles that did not exist otherwise.
Collision broadened resonance localization in tokamaks excited with ICRF waves

Abstract Collisions mediate the absorption of rf energy by maintaining velocity space gradients to drive resonant diffusion and by limiting wave-particle interaction coherence through the process of gyro phase diffusion. A code is constructed to evolve the local spectral energy absorption rate which can be exploited to ensure consistency in associated or concurrent wave propagation calculations.
Practical Design of Minimum-Weight Aircraft Structures for Strength and Flutter Requirements

Several methods for sizing the finite elements of an aircraft structural idealization to achieve minimum-weight design under combined strength and flutter-speed requirements are developed and evaluated. Two basic categories are considered: methods based on a combination of energy principles and optimality criteria; and procedures employing numerical-search techniques. Drawing upon the experience gained from studies of both of these basic methods, a resizing algorithm is developed that employs a uniform-flutter-velocity-derivative optimality criterion for flutter-critical elements and the fully-stressed-design criterion for strength-critical elements. The final result is a practical, automated approach for dealing with large-scale idealizations having both structural and mass-balance design variables.
Cross-correlation spin noise spectroscopy of heterogeneous interacting spin systems

Interacting multi-component spin systems are ubiquitous in nature and in the laboratory. As such, investigations of inter-species spin interactions are of vital importance. Traditionally, they are studied by experimental methods that are necessarily perturbative: e.g., by intentionally polarizing or depolarizing one spin species while detecting the response of the other(s). Here, we describe and demonstrate an alternative approach based on multi-probe spin noise spectroscopy, which can reveal inter-species spin interactions--under conditions of strict thermal equilibrium--by detecting and cross-correlating the stochastic fluctuation signals exhibited by each of the constituent spin species. Specifically, we consider a two-component spin ensemble that interacts via exchange coupling, and we determine cross-correlations between their intrinsic spin fluctuations. The model is experimentally confirmed using "two-color" optical spin noise spectroscopy on a mixture of interacting Rb and Cs vapors. Noise correlations directly reveal the presence of inter-species spin exchange, without ever perturbing the system away from thermal equilibrium. These non-invasive and noise-based techniques should be generally applicable to any heterogeneous spin system in which the fluctuations of the constituent components are detectable.
Diabetic Retinopathy: A clinical overview

After an introductory summary, this review presents a description of the natural course of diabetic retinopathy, then briefly considers selected pathogenetic and epidemiological concepts, and concludes with a discussion of current treatment.
Abnormal anal cytology in HIV-infected women.

Objective The purpose of this study was to assess the prevalence of and risk factors for abnormal anal cytology and human papillomavirus (HPV) infections in women who are human immunodeficiency virus (HIV) positive. Study Design We conducted an observational single center study of 100 HIV-infected women with cervical and anal specimens that were obtained for cytologic and high-risk HPV testing with Hybrid Capture 2. Results Seventeen women had abnormal anal cytology; 16 women had anal HPV; 21 women had abnormal cervical cytology, and 24 women had cervical HPV. Abnormal anal cytology was associated with cervical HPV infection, abnormal cervical cytology, and anal HPV infection in univariate analysis. In multivariate analysis, abnormal anal cytology was associated with a CD4 count 3 , a history of sexually transmitted disease, and concurrent cervical cytologic abnormality. Conclusion HIV-infected women are at high risk for abnormal cytology and HPV infections of both the anus and cervix. Risk factors for abnormal anal cytology include abnormal cervical cytology, cervical and anal HPV infections, and low CD4 count.
Structure of Starch Granules

Starch granules are synthesized in a semicrystalline structure and have characteristic morphology and properties depending on the botanical origin and the organ of the plant. Surface gelatinization studies have shown that the internal structures of starch granules are not homogeneous and vary with radial locations, from the hilum to the periphery. The internal structure of maize starch granule coincides with the biosynthesis and development of starch granules and the expression of starch synthase activities during the maturation of maize kernels. The enzyme digestibility of starch granules relates to the internal structure and the internal surface area of the starch granule as revealed by confocal laser-scattering micrographs. Short branch-chains of amylopectin (DP 6–12) destabilize the granule structures, resulting in lobed or compound starch granules and small granules. Ratios of long branch-chains to short branch-chains of amylopectin molecules affect the shape of the molecule, e.g., cylindrical versus conical shapes. The shape of the amylopectin molecule may affect the packing of the molecules in the granule and, in turn, determines the morphology and the size of the starch granule.
The formation of labyrinths, spots and stripe patterns in a biochemical approach to cardiovascular calcification

Calcification and mineralization are fundamental physiological processes, yet the mechanisms of calcification, in trabecular bone and in calcified lesions in atherosclerotic calcification, are unclear. Recently, it was shown in in vitro experiments that vascular-derived mesenchymal stem cells can display self-organized calcified patterns. These patterns were attributed to activator/inhibitor dynamics in the style of Turing, with bone morphogenetic protein 2 acting as an activator, and matrix GLA protein acting as an inhibitor. Motivated by this qualitative activator–inhibitor dynamics, we employ a prototype Gierer–Meinhardt model used in the context of activator–inhibitor-based biological pattern formation. Through a detailed analysis in one and two spatial dimensions, we explore the pattern formation mechanisms of steady state patterns, including their dependence on initial conditions. These patterns range from localized holes to labyrinths and localized peaks, or in other words, from dense to sparse activator distributions (respectively). We believe that an understanding of the wide spectrum of activator–inhibitor patterns discussed here is prerequisite to their biochemical control. The mechanisms of pattern formation suggest therapeutic strategies applicable to bone formation in atherosclerotic lesions in arteries (where it is pathological) and to the regeneration of trabecular bone (recapitulating normal physiological development).
Equivalence of the Chiral Soliton and Quark Models in Large N

We prove that the group theoretic structure of the chiral soliton model is identical to that of the naive quark model in the large-NC limit. This implies that all group theoretic calculations such as the FD ratios, gπNNgπNΔ, etc. are identical in the soliton and quark models in large N. This result is true for an arbitrary number of flavors. We also compare the two models for finite NC.
Magnetic Fields in Cluster Cores: Faraday Rotation in A400 and A2634

We present Faraday rotation data for radio sources in the centers of the Abell clusters A400 and A2634. These clusters contain large (100 kpc), tailed radio sources, each attached to the central cD galaxy. These clusters do not have strong cooling cores. Our data extend previous work on rotation measure in cluster centers to larger scales and noncooling clusters. The rotation measure, and thus the magnetic field, is ordered on scales ~10-20 kpc in both clusters. The geometry of the rotation measure appears to be determined by the distribution of the X-ray-emitting gas, rather than by the radio tails themselves. We combine our data with previously published X-ray and radio data in order to analyze the magnetic fields in all 12 clusters whose central radio sources have been imaged in rotation measure. We find that the fields are dynamically significant in most clusters. We argue that the Faraday data measure fields in the intracluster medium, rather than in a skin of the radio source. Finally, we consider the nature and maintenance of the magnetic fields in these clusters and conclude that either the cluster-wide field exists at similar levels or a weaker cluster-wide field is amplified by effects in the core.
Identifying chemicals from their Raman spectra using minimum description length

Raman spectroscopy has been a powerful means of chemical identification in a variety of fields, partly because of its non-contact nature and the speed at which measurements can be taken. Given a library of known Raman spectra, a common detection approach is to first estimate the relative amount of each chemical present, and then compare the estimated mixing coefficients to an ad hoc threshold. We present a more rigorous detection scheme by formulating the problem as one of Multiple Hypothesis Detection (MHD) and using the maximum a posteriori (MAP) decision rule to minimize the probability of classification error. The probability that a specific target chemical is present is estimated by summing the estimated probabilities of all the hypotheses containing it. Alternatively, since we do not typically have reasonable priors for the hypotheses, it is perhaps preferable to interpret the result as an abstract score corresponding to the Minimum Description Length (MDL) approach. The resulting detection performance of this approach is compared to that of several other classification algorithms.
Batch scheduling on parallel machines with dynamic job arrivals and incompatible job families

We study the scheduling problem of minimising weighted completion times on parallel identical batching machines with dynamic job arrivals and incompatible job families. Each job is associated with a family, weight (priority), release time, and size. Batching machines can process simultaneously up to a specified total size of the jobs of a particular family. The scheduling problem can be represented by Pmjrj;batch;fmlsj P wjCj. We present a mathematical model and heuristic algorithms employing different local search procedures individually and sequentially under a variable neighbourhood search scheme. We have shown that among local searches, repositioning the batches instead of jobs yields better results. The best-performing heuristic algorithm is capable of generating solutions within 0.6% of the best overall heuristic solution for each instance in a reasonable amount of time. When this heuristic is compared against the mathematical model, solutions that are 3.7% above optimal on average in the 15-job problem instances are possible.
Topology Optimization of Smart Structures Using a Homogenization Approach

Engineers are often required to design mechanical structures to meet specific loading conditions. Topology optimization automates the process of finding an optimal structural design, allowing for s...
Microwave-assisted synthesis of 1,3-benzodioxole derivatives from catechol and ketones or aldehydes

An efficient synthetic procedure for the preparation of a diverse library of 1,3-benzodioxoles was developed by applying controlled microwave heating in comparison with currently available conventional heating. Reactions were completed in less than 3 h. The isolation of product is simple, the isolated yields are good to excellent, and this method is applicable to large scale production.
Crossing the divide between homogeneous and heterogeneous catalysis in water oxidation

Abstract Enhancing the surface binding stability of chromophores, catalysts, and chromophore–catalyst assemblies attached to metal oxide surfaces is an important element in furthering the development of dye sensitized solar cells, photoelectrosynthesis cells, and interfacial molecular catalysis. Phosphonate-derivatized catalysts and molecular assemblies provide a basis for sustained water oxidation on these surfaces in acidic solution but are unstable toward hydrolysis and loss from surfaces as the pH is increased. Here, we report enhanced surface binding stability of a phosphonate-derivatized water oxidation catalyst over a wide pH range (1–12) by atomic layer deposition of an overlayer of TiO2. Increased stability of surface binding, and the reactivity of the bound catalyst, provides a hybrid approach to heterogeneous catalysis combining the advantages of systematic modifications possible by chemical synthesis with heterogeneous reactivity. For the surface-stabilized catalyst, greatly enhanced rates of water oxidation are observed upon addition of buffer bases and with a pathway identified in which O-atom transfer to OH− occurs with a rate constant increase of 106 compared to water oxidation in acid.
Imbalance fault detection of direct-drive wind turbines using generator current signals

Imbalance faults constitute a significant portion of all faults in wind turbine generators (WTGs). WTG imbalance fault detection using generator current measurements has advantages over traditional vibration-based methods in terms of cost, implementation, and system reliability. However, there are challenges in using current signals for imbalance fault detection due to low signal-to-noise ratio (SNR) of the useful information in current signals and nonstationary characteristic frequencies of imbalance faults. This paper proposes a method of using generator stator currents for imbalance fault detection of direct-drive WTGs. In the proposed method, the variable shaft rotating frequency of a WTG is estimated from one phase stator current measured from the generator terminal by using a phase lock loop (PLL) method. The estimated shaft rotating frequency is then processed by using appropriate up-sampling and variable-rate down-sampling algorithms. Consequently, the variable characteristic frequencies of imbalance faults in the spectrum of the estimated shaft rotating frequency are converted to constant values. Therefore, the signatures of wind turbine imbalance faults can be clearly identified from power spectral density (PSD) analysis of the converted shaft rotating frequency signal. Simulation and experimental results show that the proposed method is effective to detect various imbalance faults in direct-drive WTGs.
Synthesis of Benzisoxazoles by the [3 + 2] Cycloaddition of in situ Generated Nitrile Oxides and Arynes

A variety of substituted benzisoxazoles has been prepared by the [3 + 2] cycloaddition of nitrile oxides and arynes. Both components, being highly reactive intermediates, have been generated in situ by fluoride anion from readily prepared aryne precursors and chlorooximes. The reaction scope is quite general, affording a novel, direct route to functionalized benzisoxazoles under mild reaction conditions.
Characteristics of anomalous precipitation events over eastern China during the past five centuries

Characteristics of anomalous precipitation events during the past five centuries in North China (NC) and the middle-lower Yangtze River Valley (MLYRV) were investigated using the data network of dryness/wetness index (DWI) over eastern China. The high occurrence frequency of anomalous precipitation events mainly occurred at periods of high solar forcing, active volcanic eruption, and large anthropogenic forcing (the twentieth century). Coherence and dipole were the two dominant modes in spatial patterns of anomalous precipitation events. Coherent floods dominated the eighteenth and nineteenth centuries, whereas coherent droughts occurred frequently in the seventeenth and twentieth centuries. The dipole patterns of anomalous precipitation events were the most frequent in the twentieth century. NC experienced more floods in the cold periods than warm periods. Both NC and the MLYRV experienced far fewer droughts and more floods in the warm eighteenth century when natural climate forcing dominated, and more droughts in the twentieth century when anthropogenic forcing dominated. Coherent drought was the only spatial pattern of precipitation significantly associated with explosive low-latitude volcanic eruptions. The increased coherent droughts and dipole patterns in the twentieth century support the findings of previous modeling studies that the tropospheric aerosols and human-induced land cover changes play important roles in the changes of summer rainfall over eastern China.
Experimental Study of a Dual-Mode Scramjet Isolator

A constant-area isolator was fabricated and tested in conjunction with a Mach 2 hydrogen-air combustor operating at a simulated Mach 5 flight enthalpy. Predicted isolator performance was validated through pressure measurements obtained via low-frequency pressure taps. The maximum pressure ratio measured in the combustor approached the design limit of 4.5. Scramjet operability, the range of equivalence ratios over which combustion was sustained without shock-inlet interaction, was improved to 0.06-0.32, as opposed to 0.32-0.37 without the isolator. For a given change in fuel equivalence ratio, the location of the shock train was easier to control with the isolator modification. Shock-train location repeatability was found to vary somewhat with equivalence ratio. Small fluctuations in the time-resolved pressure history indicated that the shock train was relatively temporally steady for a given equivalence ratio. High-frequency pressure measurements were within a 95% confidence interval of low-frequency pressure measurements. High-frequency results indicated that an increase in pressure and large pressure fluctuations occurred near the leading edge of the shock train. Power spectral analyses also indicated that there is significant variation in the frequency content of the pressure signal upstream and downstream of the shock-train leading edge. These results suggest that methods of shock-train leading-edge detection may be developed using pressure-time history characteristics other than the pressure magnitude.
EUV and FUV observations of cataclysmic variables

In this paper we present recent results from a continuing investigation of cataclysmic variables in the 500 to 1700 A region with the Voyager ultraviolet spectrometers. Observations of outbursts show a substantial delay (~0.5 day) in the rise to maximum in the FUV (912–1200 A) with respect to optical wavelengths. Both FUV and optical light decline simultaneously. Flux distributions show a significant flattening in the FUV and with the possible exception of CPD-48 1577 no EUV flux has been observed in any catalclysmic variable. CPD-48 1577 shows a marginal, 2 σ, EUV flux.
Lambda-proton correlations in relativistic heavy ion collisions

The prospect of using {Lambda}p correlations to extract source sizes in relativistic heavy ion collisions is investigated. It is found that the strong interaction induces a large peak in the correlation function that provides more sensitive source size measurements than pp correlations under some circumstances. The prospect of using {Lambda}p correlations to measure the time lag between lambda and proton emissions is also studied. {copyright} {ital 1999} {ital The American Physical Society}
Impact of systematics on SZ-optical scaling relations

One of the central goals of multi-wavelength galaxy cluster cosmology is to unite all cluster observables to form a consistent understanding of cluster mass. Here, we study the impact of systematic effects from optical cluster catalogs on stacked Sunyaev-Zel'dovich (SZ) signals. We show that the optically predicted Y-decrement can vary by as much as 50% based on the current 2σ systematic uncertainties in the observed mass-richness relationship. Miscentering and impurities will suppress the SZ signal compared to expectations for a clean and perfectly centered optical sample, but to a lesser degree. We show that the levels of these variations and suppression are dependent on the amount of systematics in the optical cluster catalogs. We also study X-ray luminosity-dependent sub-sampling of the optical catalog and find that it creates Malmquist bias, increasing the observed Y-decrement of the stacked signal. We show that the current Planck measurements of the Y-decrement around Sloan Digital Sky Survey optical clusters and their X-ray counterparts are consistent with expectations after accounting for the 1σ optical systematic uncertainties using the Johnston mass-richness relation.
Enumeration of distinct mechanically stable disk packings in small systems

We create mechanically stable (MS) packings of bidisperse disks using an algorithm in which we successively grow or shrink soft repulsive disks followed by energy minimization until the overlaps are vanishingly small. We focus on small systems because this enables us to enumerate nearly all distinct MS packings. We measure the probability of obtaining an MS packing at packing fraction φ and find several notable results. Firstly, the probability is highly non-uniform. When averaged over narrow packing fraction intervals, the most probable MS packing occurs at the highest φ and the probability decays exponentially with decreasing φ. Even more striking, within each packing-fraction interval, the probability can vary by many orders of magnitude. By using two different packing-generation protocols, we show that these results are robust and the packing frequencies do not change qualitatively with different protocols.
Nonmitogenic survival-enhancing autocrine factors including cyclophilin A contribute to density-dependent mouse embryonic stem cell growth.

An improved understanding of the role of extracellular factors in controlling the embryonic stem cell (ESC) phenotype will aid the development of cell-based therapies. While the role of extracellular factors in controlling the pluripotency and differentiation of embryonic stem cells (ESCs) has been the subject of much investigation, the identity and role of extrinsic factors in modulating ESC growth under conditions supporting self-renewal remain largely unknown. We demonstrate that mouse ESC growth is density-dependent and that one of the mechanisms underlying this phenomenon is the action of survival-enhancing autocrine factors. Proteomic analysis of proteins secreted by mouse ESCs demonstrates significant levels of Cyclophilin A which increases the growth rate of mouse ESCs in a dose-dependent manner. Additionally, inhibition of the Cyclophilin A receptor – CD147 decreases the growth rate of mESCs. These findings identify Cyclophilin A as a novel survival-enhancing autocrine factor in mouse ESC cultures.
Use of Optically Active Cyclic N,N-Dialkyl Aminals in Asymmetric Induction

[reaction: see text]Cyclization of the optically active ketone N,N-dialkyl aminals A affords the diastereomer B as the major product with diastereoselectivities ranging from nearly 1:1 to essentially 100:0 depending on the cyclization studied.
Cubic curves from matrix models and generalized Konishi anomalies

We study the matrix model/gauge theory connection for three different = 1 models: U(N) × U(N) with matter in bifundamental representations, U(N) with matter in the symmetric representation, and U(N) with matter in the antisymmetric representation. Using Ward identities, we explicitly show that the loop equations of the matrix models lead to cubic algebraic curves. We then establish the equivalence of the matrix model and gauge theory descriptions in two ways. First, we derive generalized Konishi anomaly equations in the gauge theories, showing that they are identical to the matrix-model equations. Second, we use a perturbative superspace analysis to establish the relation between the gauge theories and the matrix models. We find that the gauge coupling matrix for U(N) with matter in the symmetric or antisymmetric representations is not given by the second derivative of the matrix-model free energy. However, the matrix-model prescription can be modified to give the gauge coupling matrix.
Palladium-catalyzed aryl-amidation. Synthesis of non-racemic N-aryl lactams

Abstract The Buchwald/Hartwig aryl amination method was used to construct a series of chiral, non-racemic N-aryl pyrrolidinones from a common pyrrolidinone precursor and the corresponding aryl bromide. The stereochemical integrity of the N-aryl lactam after cross-coupling was proven by synthesis of the racemic compounds and comparison by 1H NMR spectroscopy using Pirkle's chiral solvating agent.
Amberlite IR-120H as an efficient and versatile solid phase catalyst for nucleophilic substitution of propargylic alcohols

A highly efficient Amberlite IR-120H resin mediated nucleophilic substitution of the hydroxyl group of propargylic alcohols with a wide range of nucleophiles is reported. The reactions were achieved under very mild conditions in excellent yields.
Ceramic Matrix Composites for Rocket Engine Turbine Applications

A program to establish the potential for introducing fiber reinforced ceramic matrix composites (FRCMC) in future rocket engine turbopumps was instituted in 1987. A brief summary of the overall program (both contract and in-house research) is presented. Tests at NASA Lewis include thermal upshocks in a hydrogen/oxygen test rig capable of generating heating rates up to 2500 C/sec. Post thermal upshock exposure evaluation includes the measurement of residual strength and failure analysis. Test results for monolithic ceramics and several FRCMC are presented. Hydrogen compatibility was assessed by isothermal exposure of monolithic ceramics in high temperature gaseous hydrogen plus water vapor.
Synthesis of oxazines and thiazines by cyclodehydration of hydroxy amides and thioamides

Abstract Dihydro-1,3-oxazines and -thiazines were obtained by cyclodehydration of hydroxy amides and thioamides with PEG-linked Burgess reagent or under Mitsunobu conditions. Yields were generally higher with polymer-Burgess reagent, but both conditions failed to cyclize δ- and e-hydroxy amide precursors. In contrast, Burgess reagent was successful for the cyclodehydration of δ-hydroxy thioamide to give the expected thiazepine heterocycle, whereas the Mitsunobu reaction provided only thioacyl pyrrolidine. Both sets of reaction conditions led to thioacyl piperidine in the cyclodehydration of e-hydroxy thioamide. Thiolysis of oxazines provided hydroxy thioamide intermediates in moderate to good yield, thus establishing a new protocol for the conversion of oxazines to thiazines.
Latent Space Models for Dynamic Networks

Dynamic networks are used in a variety of fields to represent the structure and evolution of the relationships between entities. We present a model which embeds longitudinal network data as trajectories in a latent Euclidean space. We propose Markov chain Monte Carlo (MCMC) algorithm to estimate the model parameters and latent positions of the actors in the network. The model yields meaningful visualization of dynamic networks, giving the researcher insight into the evolution and the structure, both local and global, of the network. The model handles directed or undirected edges, easily handles missing edges, and lends itself well to predicting future edges. Further, a novel approach is given to detect and visualize an attracting influence between actors using only the edge information. We use the case-control likelihood approximation to speed up the estimation algorithm, modifying it slightly to account for missing data. We apply the latent space model to data collected from a Dutch classroom, and a cosp...
The place of the geophysical sciences in nineteenth century natural philosophy

The Historiography of the geophysical sciences is far from developed. This is due in part to the relatively small number of historians of science and to the growth rate of science itself. There are perhaps only several dozen persons today whose professional interests touch on the history of geophysics, or the earth sciences, expeditions and exploration, and the historical connections of these fields with other areas of scientific activity. These persons study a world scientific literature that has been growing since the late seventeenth century at a rate that has produced a doubling about every 10 to 15 years. Within the history of science, the literature of the geophysical sciences has simply not received the degree of attention given some other areas, such as the ‘Scientific Revolution’ of the sixteenth and seventeenth centuries, and the paucity of secondary materials concerning the history of geophysics reflects this. It may therefore come as no surprise to discover that at present there is no real consensus within the profession as to the major problems in the history of the geophysical sciences in their historical relationships to general physics and ther other physical sciences.
New syndrome decoding techniques for the (n,k) convolutional codes

This paper presents a new syndrome decoding algorithm for the (n,k) convolutional codes (CCs). The construction of the trellis diagram of this algorithm is simpler than the syndrome decoding algorithms of Schalkwijk, Vinck and De Paepe. The new algorithm is based on the general solution of the syndrome equation, a linear diophantine equation for the error polynomial vector E(D). The set of diophantine solutions is a coset of the CC. In this error coset a recursive, Viterbi-like, algorithm is developed to find the minimum weight error vector E(D). An example, illustrating the new decoding algorithm is given for the binary nonsystematic (3,1) CC.