cssi/SciSciGPT-SciSciNet huggingface dataset:
Polarimetric radar remote sensing of ocean surface wind

Experimental data are presented to support the development of a new concept for ocean wind velocity measurement (speed and direction) with the polarimetric microwave radar technology. This new concept has strong potential for improving the wind direction accuracy and extending the useful swath width by up to 30% for follow-on NASA spaceborne scatterometer mission to SeaWinds series. The key issue is whether there is a relationship between the polarization state of ocean backscatter and surface wind velocity at NASA scatterometer frequencies (13 GHz). An airborne Ku-band polarimetric scatterometer (POLSCAT) was developed for proof-of-concept measurements. A set of aircraft flights indicated repeatable wind direction signals in the POLSCAT observations of sea surfaces at 9-11 m/s wind speed. The correlation coefficients between co- and cross-polarized radar response of ocean surfaces have a peak-to-peak amplitude of about 0.4 and are shown to have an odd-symmetry with respect to the wind direction, unlike the normalized radar cross sections.
Stabilities of reference electrodes in molten Na2SO4 at 1200 K

Abstract The long term stabilities of several reference electrodes in contact with an acidic Na2SO4 melt at 1200 K were studied. These included the specific Na+ ion probes: Ag/Ag+ mullite or β-Al2O3 or fused-silica, and O2(Pt)/Na2OWO3/fused-silica, and the specific O2− ion probes: CaO- and Y2O3-stabilized zirconia. Corrosion attack of the electrolyte tubes led to drifts in the measured potentials. The Ag/Ag+ fused-silica and the Y2O3-stabilized zirconia electrodes were found to provide the best stabilities.
Worker turnover, industry localization, and producer size

Abstract Empirically, large employers have been shown to devote greater resources to filling vacancies than small employers. Following this evidence, this paper offers a theory of producer size based on labor market search, whereby a key factor in the determination of a producer’s total employment is the ease with which workers can be found to fill jobs that are, periodically, vacated. Since the geographic localization of industry has long been conjectured to facilitate the search process, the model provides an explanation for the observed positive association between average producer size and the magnitude of an industry’s presence within local labor markets.
Implications of grain size evolution on the seismic structure of the oceanic upper mantle

Abstract We construct a 1-D steady state channel flow model for grain size evolution in the oceanic upper mantle using a composite diffusion–dislocation creep rheology. Grain size evolution is calculated assuming that grain size is controlled by a competition between dynamic recrystallization and grain growth. Applying this grain size evolution model to the oceanic upper mantle we calculate grain size as a function of depth, seafloor age, and mantle water content. The resulting grain size structure is used to predict shear-wave velocity ( V S ) and seismic quality factor ( Q ). For a plate age of 60 Myr and an olivine water content of 1000 H/10 6 Si, we find that grain size reaches a minimum of ~ 15 mm at ~ 150 km depth and then increases to ~ 20–30 mm at a depth of 400 km. This grain size structure produces a good fit to the low seismic shear-wave velocity zone (LVZ) in oceanic upper mantle observed by surface wave studies assuming that the influence of hydrogen on anelastic behavior is similar to that observed for steady state creep. Further it predicts a viscosity of ~ 10 19 Pa·s at 150 km depth and dislocation creep to be the dominant deformation mechanism throughout the oceanic upper mantle, consistent with geophysical observations. We predict larger grain sizes than proposed in recent studies, in which the LVZ was explained by a dry mantle and a minimum grain size of 1 mm. However, we show that for a 1 mm grain size, diffusion creep is the dominant deformation mechanism above 100–200 km depth, inconsistent with abundant observations of seismic anisotropy from surface wave studies. We therefore conclude that a combination of grain size evolution and a hydrated upper mantle is the most likely explanation for both the isotropic and anisotropic seismic structure of the oceanic upper mantle. Our results also suggest that melt extraction from the mantle will be significantly more efficient than predicted in previous modeling studies that assumed grain sizes of ~ 1 mm.
Why are female small business owners in the United States less likely to apply for bank loans than their male counterparts

Female business owners are more likely to be discouraged from applying for a bank loan compared to male business owners because they fear that their application will be rejected. Analyzing data from three ‘Surveys of Small Business Finances,’ our study examines the likely reasons why they are discouraged. Using the maximum likelihood approach, we estimate the probability of loan denial. We found evidence of bank discrimination against female-owned businesses, which in turn prevents women entrepreneurs applying for credit (feedback effect). We recommend that further investigation of this feedback effect of loan denial on business owners' decision-making process be undertaken.
An Examination of Mandatorily Convertible Preferred Stock

I investigate the determinants of the use of mandatorily convertible preferred stock and assess market reaction to its issue. The security is dividend enhanced and converted into common stock within four years. Issuers have high debt ratios, low interest coverage, and bankruptcy risk. Market response to the issue was neutral suggesting the preferred issue resolved the lemon problem associated with common stock. Firms' Z-scores and abnormal returns are inversely related indicating the issues reduced financial distress. Market response was most positive for low risk firms with high cash flows.
The Failure of Drexel Burnham Lambert: Evidence on the Implications for Commercial Banks

Abstract We argue that since bank loans and publicly traded sub-investment-grade debt, or junk bonds, are close substitutes for one another, the recent failure of Drexel Burnham Lambert created a competitive opportunity for commercial banks. Consistent with this hypothesis, we observe within the commercial banking industry a positive wealth effect associated with Drexel′s failure. The distribution of the wealth effect across commercial banks and Drexel′s investment banking rivals is consistent with the wealth effect being primarily a reflection of market expectations of a return to traditional intermediated funding of sub-investment-grade debt. Journal of Economic Literature Classification Number: G2, Financial Institutions and Services.
Renormalization-group approach to the vulcanization transition

The vulcanization transition-the cross-link-density-controlled equilibrium phase transition from the liquid to the amorphous solid state-is explored analytically from a renormalization-group perspective. The analysis centers on a minimal model which has previously been shown to yield a rich and informative picture of vulcanized matter at the mean-field level, including a connection with mean-field percolation theory (i.e., random graph theory). This minimal model accounts for both the thermal motion of the constituents and the quenched random constraints imposed on their motion by the cross-links, as well as particle-particle repulsion which suppresses density fluctuations and plays a pivotal role in determining the symmetry structure (and hence properties) of the model. A correlation function involving fluctuations of the amorphous solid order parameter, the behavior of which signals the vulcanization transition, is examined, its physical meaning is elucidated, and the associated susceptibility is constructed and analyzed. A Ginzburg criterion for the width (in cross-link density) of the critical region is derived and is found to be consistent with a prediction due to de Gennes. Inter alia, this criterion indicates that the upper critical dimension for the vulcanization transition is 6. Certain universal critical exponents characterizing the vulcanization transition are computed, to lowest nontrivial order, within the framework of an expansion around the upper critical dimension. This expansion shows that the connection between vulcanization and percolation extends beyond mean-field theory, surviving the incorporation of fluctuations in the sense that pairs of physically analogous quantities (one percolation related and one vulcanization related) are found to be governed by identical critical exponents, at least to first order in the departure from the upper critical dimension (and presumably beyond). The relationship between the present approach to vulcanized matter and other approaches, such as those based on gelation-percolation ideas, is explored in the light of this connection. To conclude, some expectations for how the vulcanization transition is realized in two dimensions, developed with H. E. Castillo, are discussed.
Extrasolar Giant Planets and X-Ray Activity

We have carried out a survey of X-ray emission from stars with giant planets, combining both archival and targeted surveys. Over 230 stars have been currently identified as possessing planets, and roughly one-third of these have been detected in X-rays. We carry out detailed statistical analysis on a volume-limited sample of main-sequence star systems with detected planets, comparing subsamples of stars that have close-in planets with stars that have more distant planets. This analysis reveals strong evidence that stars with close-in giant planets are on average more X-ray active by a factor of 4 than those with planets that are more distant. This result persists for various sample selections. We find that even after accounting for observational sample bias, a significant residual difference still remains. This observational result is consistent with the hypothesis that giant planets in close proximity to the primary stars influence the stellar magnetic activity.
Review: brief interventions reduce drinking in patients not seeking treatment.

Source Citation Moyer A, Finney JW, Swearingen CE, Vergun P. Brief interventions for alcohol problems: a meta-analytic review of controlled investigations in treatment-seeking and non-treatment-see...
Sustaining long-term supply chain partnerships using price-only contracts

Abstract In this paper, we study how an informal, long-term relationship between a manufacturer and a retailer performs in turbulent market environments characterized by uncertain demand. We show that the long-term partnership based on repeated interaction is sustainable under price-only contracts when the supply chain partners are sufficiently patient. That is, the channel can be coordinated over a long time horizon when the factor whereby the members discount the future value of this trusting relationship is sufficiently high. Second, above the minimum discount factor, a range of wholesale prices exists that can sustain the long-term partnership, and there are different possible profit divisions between the two players. Third, when the market is turbulent, i.e., either the expected demand or the demand variance changes from period to period according to a probabilistic law, it is typically less possible to sustain the long-term partnership in a booming market or in a market with low demand variability. Finally, obtaining more information about future market fluctuation may not help the supply chain to sustain the long-term partnership, due to partners’ strategic considerations. With the availability of the market signal, total supply chain profits increase, but the retailer may even be worse-off.
Towards quality of experience determination for video in augmented binocular vision scenarios

With the continuous growth in the consumer markets of mobile smartphones and increasingly in augmented binocular vision wearable devices, several avenues of research investigate the relationships between the quality perceived by mobile users and the delivery mechanisms at play to support a high quality of experience for mobile users. In this paper, we present the first study that evaluates the relationships of mobile movie quality and the viewer-perceived quality thereof in an augmented binocular vision setting employing commercially available head-mounted see-through devices. We find that participants tend to overestimate the video quality when compared to a scaled representation and exhibit a significant variation of accuracy that leans onto the movie content and its dynamics. Our findings, thus, can broadly impact future media adaptation and delivery mechanisms for this new display format of mobile multimedia and spur follow-up research in this increasingly popular domain. HighlightsWe study the user-perceived video quality using optical see-through wearables.Overall findings indicate content and quality level dependency for user ratings.Users tend to slightly over-estimate the video quality level.PSNR, SSIM, and VQM relationships are similar to common QoE and QoS relationships.
Thymic neoplasm: a surgical enigma.

TUMORS of the thymus gland have been the subject of continuing review and investigation 1-7 with no appreciable improvement in the survival rate, 8,9 particularly incident to the treatment of the malignant thymoma. Several consecutive patients in 1966 and 1967 prompted the authors to review their experiences in the treatment of this entity. Accordingly the records of all patients having roentgen evidence of an anterior mediastinal neoplasm were reviewed, yielding 29 patients whose lesions grossly appeared to take origin in the thymus gland and whose histopathologic appraisal does not contradict thymic origin (Table). Associated disease syndromes are represented in this series by three patients with Cushinoid features, and a fourth with a thymoma having the epithelial histopathologic features, but without the clinical features of Cushing's syndrome. 10-15 Additionally one patient had agenesis of erythrocytes, 16-18 and one had had myocarditis 19 as well as Cushing's syndrome. Only the patient with
Recent progress in ferrofluids research: novel applications of magnetically controllable and tunable fluids

Ferrofluids are suspensions of magnetic nanoparticles that have the attractive feature of being controlled by applied magnetic fields. Ferrofluids have been studied for decades in an ever growing number of applications that take advantage of their response to applied magnetic fields. Here, we provide a summary of recent advances in established and emerging applications of ferrofluids, including applications in optics, sensors, actuators, seals, lubrication, and static/dynamic magnetically driven assembly of structures.
On the gasification reactivity of Italian sulcis coal

Abstract Some aspects of the gasification behaviour of raw and demineralized chars prepared from Italian Sulcis coal have been studied. The results obtained with demineralized chars showed that when the pyrolysis temperature is raised from 1123 to 1423 K a maximum decrease in reactivity (in CO2) of a factor of four is observed. Regardless of the pyrolysis conditions and the presence or absence of mineral matter, no significant differences in the global energy of activation were observed. In spite of the presence of significant amounts of ion-exchanged calcium in the Sulcis coal, small reactivity differences were observed between raw and demineralized chars. This behaviour was ascribed to the high sulphur content of Sulcis coal, which is responsible for the formation of catalytically inactive CaS during the pyrolysis step.
Multistage Adaptive Estimation of Sparse Signals

This paper considers sequential adaptive estimation of sparse signals under a constraint on the total sensing effort. The advantage of adaptivity in this context is the ability to focus more resources on regions of space where signal components exist, thereby improving performance. A dynamic programming formulation is derived for the allocation of sensing effort to minimize the expected estimation loss. Based on the method of open-loop feedback control, allocation policies are then developed for a variety of loss functions. The policies are optimal in the two-stage case, generalizing an optimal two-stage policy proposed by Bashan , and improve monotonically thereafter with the number of stages. Numerical simulations show gains up to several dB as compared to recently proposed adaptive methods, and dramatic gains compared to non-adaptive estimation. An application to radar imaging is also presented.
A comparative study of ribosomal proteins: linkage between amino acid distribution and ribosomal assembly

Background: Assembly of the ribosome from its protein and RNA constituents must occur quickly and efficiently in order to synthesize the proteins necessary for all cellular activity. Since the early 1960’s, certain characteristics of possible assembly pathways have been elucidated, yet the mechanisms that govern the precise recognition events remain unclear. We utilize a comparative analysis to investigate the amino acid composition of ribosomal proteins (r-proteins) with respect to their role in the assembly process. We compared small subunit (30S) r-protein sequences to those of other housekeeping proteins from 560 bacterial species and searched for correlations between r-protein amino acid content and factors such as assembly binding order, environmental growth temperature, protein size, and contact with ribosomal RNA (rRNA) in the 30S complex. Results: We find r-proteins have a significantly high percent of positive residues, which are highly represented at rRNA contact sites. An inverse correlation between the percent of positive residues and r-protein size was identified and is mainly due to the content of Lysine residues, rather than Arginine. Nearly all r-proteins carry a net positive charge, but no statistical correlation between the net charge and the binding order was detected. Thermophilic (high-temperature) r-proteins contain increased Arginine, Isoleucine, and Tyrosine, and decreased Serine and Threonine compared to mesophilic (lower-temperature), reflecting a known distinction between thermophiles and mesophiles, possibly to account for protein thermostability. However, this difference in amino acid content does not extend to rRNA contact sites, as the proportions of thermophilic and mesophilic contact residues are not significantly different. Conclusions: Given the significantly higher level of positively charged residues in r-proteins and at contact sites, we conclude that ribosome assembly relies heavily on an electrostatic component of interaction. However, the binding order of r-proteins in assembly does not appear to depend on these electrostatics interactions. Additionally, because thermophiles and mesophiles exhibit significantly different amino acid compositions in their sequences but not in the identities of contact sites, we conclude that this electrostatic component of interaction is insensitive to temperature and is not the determining factor differentiating the temperature sensitivity of ribosome assembly.
The Dependency of Folliculogenesis and Corpus Luteum Function on Pulsatile Gonadotropin Secretion in Cycling Women Using a Gonadotropin-Releasing Hormone Antagonist as a Probe

A potent GnRH antagonist, [Ac-delta 3-Pro1,p-F-D-Phe2,D-Trp3,6]GnRH (4F-Antag), was used as a probe to determine the relative dependency of ovarian cyclicity on pulsatile gonadotropin secretion. 4F-Antag was administered in a dose of 80 micrograms/kg sc twice a day for 3 consecutive days during different phases of the menstrual cycle. This treatment resulted in a prompt attenuation of pulsatile gonadotropin secretion in all women studied. Maximal suppression of gonadotropin levels, expressed as percent change from baseline, averaged 48% for LH and 22% for FSH. The reduced pulsatile gonadotropin release induced by 4F-Antag administration during the early follicular phase resulted in a significant decrease in serum estradiol levels during the period of treatment and was followed by a prolongation of follicular phase (2.4 days) and cycle length (3.5 days), but no alteration of subsequent cyclic ovarian steroid profiles compared to control cycles. Treatment initiated during the midfollicular phase 4-6 days before the expected LH surge resulted in a more dramatic decline in serum estradiol levels and prolongation of follicular phase length by 5-6 days compared to control cycles. Normal luteal function was preserved. These alterations were compatible with induction of the demise of the dominant follicle followed by the reinitiation of follicular recruitment. Administration of 4F-Antag during the midluteal phase resulted in rapid falls in serum estradiol and progesterone levels and the onset of menstrual bleeding in all women. The luteolytic effect of 4F-Antag was completely negated by the administration of hCG. These data indicate that 4F-Antag interferes with ongoing cyclic ovarian function by reducing pulsatile gonadotropin stimulation, which disrupts folliculogenic processes and induces the demise of the corpus luteum. From these findings we infer that the functional integrity of ovarian cyclicity is remarkably sensitive to brief (3 days) and partial reduction in pulsatile gonadotropin secretion.
Neutrino Mass, Dark Matter, and Leptogenesis

It is proposed that dark matter is the origin of neutrino mass, thereby linking inexorably two undisputed (and seemingly unrelated) pieces of evidence for physics beyond the Standard Model. Leptogenesis at the TeV scale may also be possible, as well as a measurable contribution to the muon anomalous magnetic moment.
A distributed debugger for Amoeba

We describe a debugger that is being developed for distributed programs in Amoeba. A major goal in our work is to make the debugger independent of the Amoeba kernel. Our design integrates many facilities found in other debuggers, such as execution replay, breakpointing, and an event-based view of the execution of the target program. This paper discusses the influence of Amoeba's architecture on the attainability of our goals and the desired functionality of the debugger. We also consider such problems as how to deal with timeouts and interactions between the target program and its environment.
The Terwilliger algebra of an almost-bipartite P- and Q-polynomial association scheme

Let Y denote a D-class symmetric association scheme with D>=3, and suppose Y is almost-bipartite P- and Q-polynomial. Let x denote a vertex of Y and let T=T(x) denote the corresponding Terwilliger algebra. We prove that any irreducible T-module W is both thin and dual thin in the sense of Terwilliger. We produce two bases for W and describe the action of T on these bases. We prove that the isomorphism class of W as a T-module is determined by two parameters, the dual endpoint and diameter of W. We find a recurrence which gives the multiplicities with which the irreducible T-modules occur in the standard module. We compute this multiplicity for those irreducible T-modules which have diameter at least D-3.
The circumstellar extinction of planetary nebulae

We analyze the dependence of circumstellar extinction on core mass for the brightest planetary nebulae (PNs) in the Magellanic Clouds and M31. We show that in all three galaxies, a statistically significant correlation exists between the two quantities, such that high-core mass objects have greater extinction. We model this behavior and show that the relation is a simple consequence of the greater mass loss and faster evolution times of high-mass stars. The relation is important because it provides a natural explanation for the invariance of the [O III] λ5007 planetary nebula luminosity function (PNLF) with population age: bright Population I PNs are extinguished below the cutoff of the PNLF. It also explains the counter-intuitive observation that intrinsically luminous Population I PNs often appear fainter than PNs from older, low-mass progenitors.
International Trade and the Accumulation of Human Capital

Changes in the terms of trade affect both the incentives and the ability of individuals to purchase education in a credit-constrained economy. A model is developed that shows how individual decision-making is affected in a small economy when it opens up to trade. Empirical results indicate that credit constraints are an important factor influencing school enrollment rates, particularly in low income countries. As a result, countries with low human capital stocks tend to increase their accumulation of human capital with increased trade. The response in high income countries is more muted.
A self-calibrating optomechanical force sensor with femtonewton resolution

We report the development of an ultrasensitive optomechanical sensor designed to improve the accuracy and precision of force measurements with atomic force microscopy. The sensors reach quality factors of 4.3 × 106 and force resolution on the femtonewton scale at room temperature. Self-calibration of the sensor is accomplished using radiation pressure to create a reference force. Self-calibration enables in situ calibration of the sensor in extreme environments, such as cryogenic ultra-high vacuum. The senor technology presents a viable route to force measurements at the atomic scale with uncertainties below the percent level.
Stereoselective fragmentation of a tricyclic diester leading to a potent chorismate mutase transition state inhibitor

Abstract High kinetic stereoselectivity in the base-catalyzed fragmentation of 1,7-dicarbomethoxytricyclo[3.3.1.02,7]nonan-4-one 11 led to a convergent, high-yielding synthesis of 6 .
Landau quantization and quasiparticle interference in the three-dimensional Dirac semimetal Cd3As2

Three-dimensional Dirac semimetals such as Cd3As2 are attracting attention because their electronic structure can be considered to be the three-dimensional analogue of graphene’s. Low-temperature scanning tunnelling measurements of the 112 cleavage plane of Cd3As2 now reveal its electronic structure down to atomic length scales, as well as its Landau spectrum and quasiparticle interference pattern.
Molecular Hydrogen and Global Star Formation Relations in Galaxies

Weusehydrodynamicalsimulationsof diskgalaxiestostudyrelationsbetweenstarformationandpropertiesof the molecular ISM. We implement a model for the ISM that includes low-temperature (T < 10 4 K) cooling, directly ties the SFR to the molecular gas density, and accounts for the destruction of H2 by an interstellar radiation field from young stars. We demonstrate that the ISM and star formation model simultaneously produces a spatially resolved molecular gas surface density Schmidt-Kennicutt relation of the formSFR / � n mol H2 , with nmol � 1:4 independent of galaxy mass, and a total gas surface densityYSFR relationSFR / � n tot gas with a power-law index that steepens from ntot � 2 for large galaxies to ntotk4 for small dwarf galaxies. We show that deviations from the disk-averaged � SFR / � 1:4 gas correlation determined by Kennicutt owe primarily to spatial trends in the molecular fractionfH2 and may explain observed deviations from the global Schmidt-Kennicutt relation. In our model, such deviations occur in regionsof theISMwhere thefraction of gasmassinmolecularformisdeclining orsignificantlylessthanunity.Long gas consumption timescales in low-mass and low surface brightness galaxies may owe to their small fractions of molecular gas rather than mediation by strong supernova-driven winds. Our simulations also reproduce the observed relations between ISM pressure and molecular fraction and between SFR, gas surface density, and disk angular frequency. We show that the Toomre criterion that accounts for both gas and stellar densities correctly predicts the onset of star formation in our simulated disks. We examine the density and temperature distributions of the ISM in simulated galaxies and show that the density pdf generally exhibits a complicated structure with multiple peaks corresponding to different temperature phases of the gas. The overall density pdf can be well modeled as a sum of lognormal pdf's corresponding to individual, approximately isothermal phases. We also present a simple method to mitigate numerical Jeansfragmentation of dense,cold gas in SPH codesthrough the adoption of a density-dependent pressure floor. Subject headingg Galaxy: evolution — Galaxy: formation — Galaxy: structure — ISM: general
The Urban-Rural Income Gap in China: Implications for Global Food Markets

With the exceptions of the agricultural and financial sectors, China has essentially become a market economy, and indications are that it will enjoy a sustained period of high economic growth well into the twenty-first century (Naughton). However, growth in China's agriculture has slowed since 1984 (Crook 1996, Wen), and this seems to be related to a policy bias against agriculture. From 1978 to 1984, agriculture grew at 7.6%, but this slowed to 4% from 1985 to 1994 (Crook 1996). Agriculture remains underdeveloped in China largely because the government still purchases (at fixed prices) more than 50% of the grain sold off the farm. The government forces some farmers to produce grain and supports this policy by discouraging integration between the rural and urban economies.' As a result, rural product and factor markets are distorted. Nowhere is this more evident than in the labor market (Banister; Carter, Zhong, and Cai; Cook; Knight and Song; Riskin; Taylor; Yang and Zhou). Despite large increases in rural nonagricultural employment since 1978, the absorption has not kept up with population growth, and the job of shifting labor out of agriculture is far from complete. As of 1995, there were approximately 50 million more farmers in China than at the be-
Performance limitations of silicon bipolar transistors

As the very large-scale integration (VLSI) era begins, the limitations to improving integration in silicon semiconductor technology are being studied, and the integration of many millions of components per single integrated circuit chip is predicted. In this paper we consider some performance limitations of silicon bipolar transistors, assuming our ability to fabricate small geometric devices, by device analysis using an accurate two-dimensional numerical solution of classic semiconductor transport equations. The applicability of mathematical equations used to represent carrier transport in small geometric bipolar transistors and silicon-material parameters, such as bandgap narrowing with doping, ionization coefficients, and lifetime, used in the model has also been considered. The terminal characteristics, the internal behavior, and performance limitations due to voltage and current operating levels of bipolar transistors with emitter depths and basewidths ranging from 0.4 µm to 30 nm have been analyzed. The results of our calculations indicate that the f T and f_{\max} of a bipolar transistor of 1 × 1 µm2emitter size, 30 nm emitter depth, and 30 nm basewidth are about 89 and 6.1 GHz, respectively, at 0.73 mA collector current. Maximum V BC before base-collector junction breakdown at this current level is -2 V. For a device of 1 × 1 µm2emitter size, 100 nm emitter depth, and 100 nm basewidth, the calculated values of f T and f_{\max} are 16.8 and 9.9 GHz, respectively, at a collector current of 0.38 mA.
Multivariate Gaussians, Semidefinite Matrix Completion, and Convex Algebraic Geometry

We study multivariate normal models that are described by linear constraints on the inverse of the covariance matrix. Maximum likelihood estimation for such models leads to the problem of maximizing the determinant function over a spectrahedron, and to the problem of characterizing the image of the positive definite cone under an arbitrary linear projection. These problems at the interface of statistics and optimization are here examined from the perspective of convex algebraic geometry.
The Effect of Novel Surface Textures on Tappet Shims on Valvetrain Friction and Wear

In an engine, the valvetrain contributes about 6–10% of the total frictional loss depending on the architecture. The cam and the tappet contact in a direct acting mechanical bucket-type valvetrain offers opportunities for friction reduction. Work has been done in the past to reduce the frictional loss at the cam and tappet contact through use of lightweight materials to reduce the reciprocating mass, the improved surface finish, and the low friction thin film coatings. This investigation explored the potential for additional friction reduction through the use of novel surface textures on tappet shims. The surface textures were produced on tappet shims using two techniques: (a) regular patterns like parallel line V-grooves, and square grooves, circular V-grooves, and spiral V-grooves using a diamond tool, and (b) random irregular dimples using either ceramic peening or steel shot peening. The friction performance of these shims was compared with standard production shims and isotropic finish on production ...
Allosteric Inhibitor Development Targeting HIV‐1 Integrase

HIV-1 integrase (IN) is one of three essential enzymes for viral replication, and is a focus of ardent antiretroviral drug discovery and development efforts. Diligent research has led to the development of the strand-transfer-specific chemical class of IN inhibitors, with two compounds from this group, raltegravir and elvitegravir, advancing the farthest in the US Food and Drug Administration (FDA) approval process for any IN inhibitor discovered thus far. Raltegravir, developed by Merck & Co., has been approved by the FDA for HIV-1 therapy, whereas elvitegravir, developed by Gilead Sciences and Japan Tobacco, has reached phase III clinical trials. Although this is an undoubted success for the HIV-1 IN drug discovery field, the emergence of HIV-1 IN strand-transfer-specific drug-resistant viral strains upon clinical use of these compounds is expected. Furthermore, the problem of strand-transfer-specific IN drug resistance will be exacerbated by the development of cross-resistant viral strains due to an overlapping binding orientation at the IN active site and an equivalent inhibitory mechanism for the two compounds. This inevitability will result in no available IN-targeted therapeutic options for HIV-1 treatment-experienced patients. The development of allosterically targeted IN inhibitors presents an extremely advantageous approach for the discovery of compounds effective against IN strand-transfer drug-resistant viral strains, and would likely show synergy with all available FDA-approved antiretroviral HIV-1 therapeutics, including the IN strand-transfer-specific compounds. Herein we review the concept of allosteric IN inhibition, and the small molecules that have been investigated to bind non-active-site regions to inhibit IN function.
Symmetries of 2-D gravity

Abstract Two-dimensional gravity in the light-cone gauge was shown to exhibit an underlying sl (2, R ) current algebra. It is the purpose of this note to offer a possible explanation about the origin of this important algebra. The essential point is that two-dimensional gravity is governed by a topological field theory. The gauge group is sl (2, R ) and it is this enhanced gauge group that yields Polyakov's current algebra.
Ideal boundaries of pseudo-Anosov flows and uniform convergence groups with connections and applications to large scale geometry

Given a general pseudo-Anosov flow in a closed three manifold, the orbit space of the lifted flow to the universal cover is homeomorphic to an open disk. We construct a natural compactification of this orbit space with an ideal circle boundary. If there are no perfect fits between stable and unstable leaves and the flow is not topologically conjugate to a suspension Anosov flow, we then show: The ideal circle of the orbit space has a natural quotient space which is a sphere. This sphere is a dynamical systems ideal boundary for a compactification of the universal cover of the manifold. The main result is that the fundamental group acts on the flow ideal boundary as a uniform convergence group. Using a theorem of Bowditch, this yields a proof that the fundamental group of the manifold is Gromov hyperbolic and it shows that the action of the fundamental group on the flow ideal boundary is conjugate to the action on the Gromov ideal boundary. This gives an entirely new proof that the fundamental group of a closed, atoroidal 3‐manifold which fibers over the circle is Gromov hyperbolic. In addition with further geometric analysis, the main result also implies that pseudo-Anosov flows without perfect fits are quasigeodesic flows and that the stable/unstable foliations of these flows are quasi-isometric foliations. Finally we apply these results to (nonsingular) foliations: if a foliation is R‐covered or with one sided branching in an aspherical, atoroidal three manifold then the results above imply that the leaves of the foliation in the universal cover extend continuously to the sphere at infinity. 37C85, 37D20, 53C23, 57R30; 58D19, 37D50, 57M50
UPDATE ON THE CETUS POLAR STREAM AND ITS PROGENITOR

We trace the Cetus Polar Stream (CPS) with blue horizontal branch and red giant stars from Data Release 8 of the Sloan Digital Sky Survey. Using a larger data set than was available previously, we are able to refine the measured distance and velocity to this tidal debris star stream in the south Galactic cap. Assuming that the tidal debris traces the progenitor's orbit, we fit an orbit to the CPS and find that the stream is confined between ~24 and 36?kpc on a rather polar orbit inclined 87? to the Galactic plane. The eccentricity of the orbit is 0.20, and the period is ~700?Myr. If we instead matched N-body simulations to the observed tidal debris, these orbital parameters would change by 10% or less. The CPS stars travel in the opposite direction to those from the Sagittarius tidal stream in the same region of the sky. Through N-body models of satellites on the best-fitting orbit, and assuming that mass follows light, we show that the stream width, line-of-sight depth, and velocity dispersion imply a progenitor of 108 M ?. However, the density of stars along the stream requires either a disruption time on the order of one orbit or a stellar population that is more centrally concentrated than the dark matter. We suggest that an ultrafaint dwarf galaxy progenitor could reproduce a large stream width and velocity dispersion without requiring a very recent deflection of the progenitor into its current orbit. We find that most Cetus stars have metallicities of ?2.5 < [Fe/H]?<?2.0, similar to the observed metallicities of the ultrafaint dwarfs. Our simulations suggest that the parameters of the dwarf galaxy progenitors, including their dark matter content, could be constrained by observations of their tidal tails through comparison of the debris with N-body simulations.
SYNTHESIS AND SPECTRAL DATA OF SOME NEW N-NITROSO-N-PHENYLHYDROXYLAMINE (CUPFERRON) DERIVATIVES

(1998). SYNTHESIS AND SPECTRAL DATA OF SOME NEW N-NITROSO-N-PHENYLHYDROXYLAMINE (CUPFERRON) DERIVATIVES. Organic Preparations and Procedures International: Vol. 30, No. 4, pp. 439-446.
Strain measurement by diffraction at LANSCE

Neutron diffraction is a unique technique for non-destructive strain measurement within crystalline solids. The technique has achieved recognition but is limited by lack of beam time and the compromises involved in using instruments designed for powder diffraction. This paper summarizes its importance, lists the capabilities of the Los Alamos (pulsed) neutron scattering center (LANSCE) and briefly describes a conceptual dedicated instrument.
Mode-coupling theory for heteropolymers

We study the Langevin dynamics of a heteropolymer by means of a mode-coupling approximation scheme, giving rise to a set of coupled integro-differential equations relating the response and correlation functions. The analysis shows that there is a regime at low temperature characterized by out-of-equilibrium dynamics, with violation of time-translational invariance and of the fluctuation-dissipation theorem. The onset of aging dynamics at low temperatures gives insight into the nature of the slow dynamics of a disordered polymer. We also introduce a renormalization-group treatment of our mode-coupling equations, which supports our analysis, and might be applicable to other systems.
DETECTING EARTH-MASS PLANETS WITH GRAVITATIONAL MICROLENSING

We show that Earth-mass planets orbiting stars in the Galactic disk and bulge can be detected by monitoring microlensed stars in the Galactic bulge. The star and its planet act as a binary lens which generates a light curve that can differ substantially from the light curve due only to the star itself. We show that the planetary signal remains detectable for planetary masses as small as an Earth mass when realistic source star sizes are included in the light curve calculation. These planets are detectable if they reside in the "lensing zone," which is centered between 1 and 4 AU from the lensing star and spans about a factor of 2 in distance. If we require a minimum deviation of 4% from the standard point-lens microlensing light curve, then we find that more than 2% of all M⊕ planets and 10% of all 10 M⊕ in the lensing zone can be detected. If a third of all lenses have no planets, a third have 1 M⊕ planets, and the remaining third have 10 M⊕ planets then we estimate that an aggressive ground-based microlensing planet search program could find one Earth-mass planet and half a dozen 10 M⊕ planets per year.
Photon bubbles in the circumstellar envelopes of young massive stars

We show that the optically thick dusty envelopes surrounding young high-mass stars are subject to the photon bubble instability. The infrared radiation passing through the envelope amplifies magnetosonic disturbances, with growth rates in our local numerical radiation MHD calculations that are consistent with a linear analysis. Modes with wavelengths comparable to the gas pressure scale height grow by more than 2 orders of magnitude in 1000 yr, reaching nonlinear amplitudes within the envelope lifetime. If the magnetic pressure in the envelope exceeds the gas pressure, the instability develops into trains of propagating shocks. Radiation escapes readily through the low-density material between the shocks, enabling accretion to continue despite the Eddington limit imposed by the dust opacity. The supersonic motions arising from the photon bubble instability can help explain the large velocity dispersions of hot molecular cores, while conditions in the shocked gas are suitable for maser emission. We conclude that the photon bubble instability may play a key role in the formation of massive stars.
Low-Frequency Gravitational Waves from Black Hole MACHO Binaries

Nakamura et al. have recently estimated the initial distribution of binary MACHOs in galactic halos, assuming that the MACHOs are primordial black holes of mass ~0.5 M☉, and considered their coalescence as a possible source for ground-based interferometer gravitational wave detectors such as LIGO. Evolving their binary distribution forward in time to the present, the low-frequency (10 -->−5 Hz −1 Hz) spectrum of gravitational waves associated with such a population of compact binaries is calculated. The resulting gravitational waves would form a strong stochastic background in proposed space interferometers such as LISA and the OMEGA. Low-frequency gravitational waves are likely to become a key tool for determining the properties of binaries within the dark MACHO population.
Life as a planetary phenomenon.

The success of recent spacecraft from the U.S.A. and the U.S.S.R. has given us a wealth of new data about the planets in our solar system. We can now develop a much better rationale for the reasons that abundant life is only found on our planet. Mars, smaller and more distant from the Sun, may nevertheless hold clues to the early development of Earth's atmosphere. The origin of life on Mars early in that planet's history cannot be ruled out. Titan offers a contemporary example of extremely primitive conditions, where chemical reactions resembling those that preceded the development of life on Earth may be occurring today. Venus and Jupiter illustrate the need for a planet to be the right size and the right distance from the sun if chemical evolution leading to the origin of life is to occur.
AN EVALUATION OF SCLERAL TONOMETRY* ITS RELIABILITY, VALIDITY AND CLINICAL APPLICABILITY

(1956). An Evaluation of Scleral Tonometry* Its Reliability, Validity and Clinical Applicability. Clinical and Experimental Optometry: Vol. 39, No. 5, pp. 203-210.
Macro crises and targeting transfers to the poor

A central question for policy makers concerned with helping the poor through a macro crisis is how to target scarcer resources at a time of greater need. Technical arguments suggest that finer targeting through tightening individual programs or reallocation resources towards more tightly targeted programs uses resources more efficiently for poverty reduction. These arguments survive even when the greater informational costs and the incentive effects of finer targeting are taken into account. But political economy arguments suggest that finer targeting will end up with fewer resources allocated to that program, and that looser targeting, because it knits together the interests of the poor and the near poor, may generate greater resources and hence be more effective for poverty reduction despite being 'leakier.' Overall the policy advice to tighten targeting and to avoid more loosely targeted programs during crises needs to be given with consideration caution. However, the advice to design transfer systems with greater flexibility, in the technical and the political economy senses, is strengthened by the arguments presented here. The case for external assistance to design flexible transfer systems ex ante and to relieve the painful tradeoffs in targeting during a crisis is also shown to be strong.
Construction theory, self-replication, and the halting problem

This essay aims to propose construction theory, a new domain of theoretical research on machine construction, and use it to shed light on a fundamental relationship between living and computational systems. Specifically, we argue that self-replication of von Neumann's universal constructors holds a close similarity to circular computational processes of universal computers that appear in Turing's original proof of the undecidability of the halting problem. The result indicates the possibility of reinterpreting a self-replicating biological organism as embodying an attempt to solve the halting problem for a diagonal input in the context of construction. This attempt will never be completed because of the indefinite cascade of self-computation-construction, which accounts for the undecidability of the halting problem and also agrees well with the fact that life has maintained its reproductive activity for an indefinitely long period of time. © 2008 Wiley Periodicals, Inc. Complexity, 2008
On radial and conical Fourier multipliers

We investigate connections between radial Fourier multipliers on ℝ d and certain conical Fourier multipliers on ℝd+1. As an application we obtain a new weak type endpoint bound for the Bochner–Riesz multipliers associated with the light cone in ℝd+1, where d≥4, and results on characterizations of L p →L p,ν inequalities for convolutions with radial kernels.
Selective reduction of aldehydes via BINOL-Zr complex

Abstract An easily assembled catalyst from (±)-BINOL (1,1′-bi-naphthol) and Zr(OiPr)4·iPrOH selectively reduces aldehydes at room temperature. Ketones remain intact under these conditions. A catalytic amount of BINOL–Zr complex in the presence of 2-propanol also effectively reduces a variety of chiral and achiral aldehydes.