cssi/SciSciGPT-SciSciNet huggingface dataset:
Increasing system dependability through architecture-based self-repair

One increasingly important technique for improving system dependability is to provide mechanisms for a system to adapt at run time in order to accommodate varying resources, system errors, and changing requirements. For such "self-repairing" systems one of the hard problems is determining when a change is needed, and knowing what kind of adaptation is required. In this paper we describe a partial solution in which stylized architectural design models are maintained at run time as a vehicle for automatically monitoring system behavior, for detecting when that behavior falls outside of acceptable ranges, and for deciding on a high-level repair strategy. The main innovative feature of the approach is the ability to specialize a generic run time adaptation framework to support particular architectural styles and properties of interest. Specifically, a formal description of an architectural style defines for a family of related systems the conditions under which adaptation should be considered, provides an analytic basis for detecting anomalies, and serves as a basis for developing sound repair strategies.
Ramification points of Seiberg-Witten curves

When the Seiberg-Witten curve of a four-dimensional N = 2 supersymmetric gauge theory wraps a Riemann surface as a multi-sheeted cover, a topological constraint requires that in general the curve should develop ramification points. We show that, while some of the branch points of the covering map can be identified with the punctures that appear in the work of Gaiotto, the ramification points give us additional branch points whose locations on the Riemann surface can have dependence not only on gauge coupling parameters but on Coulomb branch parameters and mass parameters of the theory. We describe how these branch points can help us to understand interesting physics in various limits of the parameters, including Argyres-Seiberg duality and Argyres-Douglas fixed points.
Polymeric materials for Solar Sail: The combined effects of polymer thickness, radiation, and temperature

The feasibility and the performance of solar sail depend critically on the availability of light materials and extremely thin polymeric films. The main requirements imposed on solar sail materials are analyzed in depth. The potential effects of the space environment are discussed in detail, with emphasis on the radiation-temperature-polymeric film thickness relationships. It is shown that the radiation component of the space environment triggers two competing degradation processes (erosion and depolymerization) and that both processes act towards the decrease in the glass transition temperature.
Palladium‐Catalyzed C(sp3)H Arylation of N‐Boc Benzylalkylamines via a Deprotonative Cross‐Coupling Process

Diarylmethylamines are key intermediates and products in the pharmaceutical industry. Herein we disclose a novel method toward the synthesis of these important compounds via CH functionalization. Presented is a reversible deprotonation of N-Boc benzylalkylamines at the benzylic CH with in situ arylation by a NiXantPhos-based palladium catalyst (50-93 % yield, 29 examples). The method is also successful with N-Boc-tetrahydroisoquinolines. The advantages of this method are it avoids strong bases, low temperatures, and the need to transmetallate to main group metals for the coupling.
Initial results of operating the rocketdyne undulator in a tapered configuration

Abstract The near-infrared Rocketdyne/Stanford free electron laser (FEL) uses a very-high-quality precision undulator whose field strength and field taper are adjustable. The Rocketdyne undulator has been operated in both an amplifier configuration, as in the master-oscillator power amplifier (MOPA) experiments, and an oscillator configuration, as in the photocathode and tapered-undulator experiments. The tapered-undulator experiment was performed at the Stanford Photon Research Laboratory (SPRL) using an electron beam supplied by the Mark III rf-linac. During the experiment we observed sustained oscillations as the undulator magnetic-field taper was continuously tuned from 0% to 10%. We observed ∼1.2% extraction efficiency for a magnetic-field taper of 9.6%. During the same experiment we observed sustained oscillations as the undulator gap was continuously varied over 120 mil. Details of the experiment are presented.
Fluoroolefin containing dipeptide isosteres as inhibitors of dipeptidyl peptidase IV(CD26)

Abstract ( Z )-( S )Ala- ψ [CF=C]-( RS )-Pro containing N , O -diacylhydroxamic acid type protease inhibitors have been prepared for the study of the influence of prolylamide bond geometry on the inhibition of dipeptidyl peptidase IV(CD26). The synthesis is based upon the use of tert -butyl α-fluoro-α-trimethylsilylacetate in a variation of the Peterson olefination procedure to construct the necessary functionalized fluoroolefin.
Trade liberalization, employment flows, and wage inequality in Brazil

Using nationally representative, economywide data, this paper investigates the relative importance of trade-mandated effects on industry wage premia; industry and economywide skill premia; and employment flows in accounting for changes in the wage distribution in Brazil during the 1988-95 trade liberalization. Unlike in other Latin American countries, trade liberalization appears to have made a significant contribution toward a reduction in wage inequality. These effects have not occurred through changes in industry-specific (wage or skill) premia. Instead, they appear to have been channeled through substantial employment flows across sectors and formality categories. Changes in the economywide skill premium are also important.
Infinite Index Subfactors and the GICAR Categories

Given a II1-subfactor \({A \subset B}\) of arbitrary index, we show that the rectangular GICAR category, also called the rectangular planar rook category, faithfully embeds as A − A bimodule maps among the bimodules \({\bigotimes_A^n L^2(B)}\). As a corollary, we get a lower bound on the dimension of the centralizer algebras \({A_{0}^{'}\,\cap\,A_{2n}}\) for infinite index subfactors, and we also get that \({A_{0}^{'}\,\cap\,A_{2n}}\) is nonabelian for \({n \geq 2}\), where \({(A_n)_{n \geq 0}}\) is the Jones tower for \({A_0 = A \subset B = A_1}\). We also show that the annular GICAR/planar rook category acts as maps amongst the A-central vectors in \({\bigotimes_A^n L^2(B)}\), although this action may be degenerate. We prove these results in more generality using bimodules. The embedding of the GICAR category builds on work of Connes and Evans, who originally found GICAR algebras inside Temperley–Lieb algebras with finite modulus.
Non-Supersymmetric String Theory

A class of non-supersymmetric string backgrounds can be constructed using twists that involve space-time fermion parity. We propose a non-perturbative definition of string theory in these backgrounds via gauge theories with supersymmetry softly broken by twisted boundary conditions. The perturbative string spectrum is reproduced, and qualitative effects of the interactions are discussed. Along the way, we find an interesting mechanism for inflation. The end state of closed string tachyon condensation is a highly excited state in the gauge theory which, in all likelihood, does not have a geometric interpretation.
Geographic Variation in Characteristics of Postpartum Women Using Female Sterilization

BACKGROUND: Southern states have higher rates of female sterilization compared with other areas of the United States and the reasons for this are not well understood. We examined whether low-income and racial/ethnic minority women who were previous targets of coercive practices disproportionately report using sterilization in the South. METHODS: We used data from 12 states participating in the Pregnancy Risk Assessment Monitoring System that collected information on womens contraceptive method use between 2006 and 2009. We categorized states according to geographic region: South Midwest/West and Northeast. Within each region we computed the percentage of women using sterilization according to their demographic and obstetric characteristics and estimated multivariable-adjusted prevalence ratios to evaluate whether the same characteristics were associated with sterilization use. FINDINGS: The percentage of postpartum women using sterilization ranged from 5.0% to 9.9% in the Northeast 8.9% to 10.6% in the Midwest/West and 11.6% to 22.4% in the South. Women in nearly all subgroups in Southern states were more likely to use sterilization than women in the Northeast. After multivariable adjustment there were no differences in the prevalence of sterilization for Blacks compared with Whites in the Northeast (0.76; 95% CI 0.55-1.06) Midwest/West (0.91; 95% CI 0.80-1.04) and South (0.96; 95% CI 0.85-1.07). Women with Medicaid-paid deliveries (vs. private insurance) had a higher prevalence of sterilization in all regions (p < .05). CONCLUSIONS: These findings do not indicate that low-income and racial/ethnic minority women in the South use sterilization at disproportionately higher rates compared with other regions and suggest that other differences such as social norms and family planning policies may contribute to this geographic variation. Copyright (c) 2015 Jacobs Institute of Womens Health. Published by Elsevier Inc. All rights reserved.
Assembly of computers to command and control a robot

There is a growing consensus among predictors of science that the world is about to witness the evolution of what might be called a new species---the robot. Whereas, animal evolution was a trial-and-error process, robot evolution appears likely to be carefully contrived. Starting where animal evolution left off, that is, with man, robot evolution promises to excel man is some respects, and be excelled by him in others.
Full self-consistency versus quasiparticle self-consistency in diagrammatic approaches: exactly solvable two-site Hubbard model

Self-consistent solutions of Hedin's equations (HE) for the two-site Hubbard model (HM) have been studied. They have been found for three-point vertices of increasing complexity (Γ = 1 (GW approximation), Γ1 from the first-order perturbation theory, and the exact vertex Γ(E)). Comparison is made between the cases when an additional quasiparticle (QP) approximation for Green's functions is applied during the self-consistent iterative solving of HE and when QP approximation is not applied. The results obtained with the exact vertex are directly related to the present open question-which approximation is more advantageous for future implementations, GW + DMFT or QPGW + DMFT. It is shown that in a regime of strong correlations only the originally proposed GW + DMFT scheme is able to provide reliable results. Vertex corrections based on perturbation theory (PT) systematically improve the GW results when full self-consistency is applied. The application of QP self-consistency combined with PT vertex corrections shows similar problems to the case when the exact vertex is applied combined with QP sc. An analysis of Ward Identity violation is performed for all studied in this work's approximations and its relation to the general accuracy of the schemes used is provided.
Dynamics groups of asynchronous cellular automata

We say that a finite asynchronous cellular automaton (or more generally, any sequential dynamical system) is ?-independent if its set of periodic points are independent of the order that the local functions are applied. In this case, the local functions permute the periodic points, and these permutations generate the dynamics group. We have previously shown that exactly 104 of the possible $2^{2^{3}}=256$ cellular automaton rules are ?-independent. In the article, we classify the periodic states of these systems and describe their dynamics groups, which are quotients of Coxeter groups. The dynamics groups provide information about permissible dynamics as a function of update sequence and, as such, connect discrete dynamical systems, group theory, and algebraic combinatorics in a new and interesting way. We conclude with a discussion of numerous open problems and directions for future research.
Effect of EMF on minimum cost power transmission

Concern about electromagnetic field (EMF) effects on human health has heightened public awareness of overhead transmission lines planning and operation. The objective of this paper is to study the effect of EMF constraints on optimal power generation scheduling. This study considers reducing EMF levels associated with critical transmission lines by redistributing the scheduled power generation, while maintaining the minimum operation cost as an objective. The EMF constraints are given in terms of control variables and fuzzy sets are utilized to model the tradeoff between minimizing the objective function and satisfying EMF constraints. Numerical results for the application of the proposed approach to test systems are discussed. >
Introduction—optimal treatment of malignancies associated with hyperuricemia ☆

A SYMPOSIUM entitled “Optimal Treatment of Malignancies Associated With Hyperuricemia” was held prior to the 42nd Annual Meeting of the American Society of Hematology in December 2000 in San Francisco, CA. Sponsored by the University of Tennessee, the symposium featured a group of leading clinical oncologists who reviewed the current treatment of malignancies associated with tumor lysis syndrome (TLS), with a focus on the current management of hyperuricemia, a key metabolic disorder in TLS. This supplement to Seminars in Hematology highlights novel strategies that may be implemented to reduce the morbidity and mortality associated with TLS, especially in patients with lymphoproliferative malignancies. TLS is a potentially fatal and metabolic complication that can occur in some patients with cancer.6,9,17 It is often associated with malignancies that have large tumor burdens and high proliferative fractions, including high-grade lymphomas and leukemias with high tumor burden.6~9~10~17~i9 Hyperuricemia, hyperphosphatemia, hyperkalemia, and hypocalcemia are the hallmark signs of TLS and occur when the kidneys cannot process and excrete the large amounts of intracellular contents (including purine, potassium, and phosphorus) released during chemotherapy-induced cell lysis. The increased serum levels of these byproducts tax the mechanisms of normal renal excretion and can progress rapidly to acute renal failure and occasional fatal metabolic derangernent.7~10~17~i8 In some patients with cancer, the malignancy itself can raise uric acid levels, and treatment with cytotoxic agents, especially at high doses, further worsens the condition of hyperuricemia. TLS usually occurs at the time of maximal tumor cell lysis, beginning a few hours after the initiation of chemotherapy and persisting for 3 to 7 days. l7 In a comprehensive article, Dr Sima Jeha has provided an overview of the etiology and management of hyperuricemia and TLS. Uric acid is the end product of purine metabolism that is normally excreted by the kidneys.ir In the liver, hypoxanthine and xanthine are catalyzed sequentially by xanthine oxidase to uric acid.lg Uric acid is poorly soluble in the highly acidic environment of the urine, and hence there is a significant potential for urate crystallization in the renal tubules as uric acid concentrations increase.17,19 In normal individuals, moderately elevated serum levels of uric acid are usually corrected by increased excretion. In patients with cancer, however, uric acid crystals can cause an obstructive uropathy, decreasing the clearance of urates, as well as phosphorus, and increasing the potential for acute renal failure. To prevent renal failure, management of TLS is aimed at increasing urine production, decreasing uric acid and phosphorus concentrations, and increasing the solubility of uric acid and phosphorus in
YELLOW AND RED SUPERGIANTS IN THE LARGE MAGELLANIC CLOUD

Due to their transitionary nature, yellow supergiants (YSGs) provide a critical challenge for evolutionary modeling. Previous studies within M31 and the Small Magellanic Cloud show that the Geneva evolutionary models do a poor job at predicting the lifetimes of these short-lived stars. Here, we extend this study to the Large Magellanic Cloud (LMC) while also investigating the galaxy's red supergiant (RSG) content. This task is complicated by contamination by Galactic foreground stars that color and magnitude criteria alone cannot weed out. Therefore, we use proper-motions and the LMC's large systemic radial velocity (~278?km?s?1) to separate out these foreground dwarfs. After observing nearly 2000 stars, we identified 317 probable YSGs, 6 possible YSGs, and 505 probable RSGs. Foreground contamination of our YSG sample was ~80%, while that of the RSG sample was only 3%. By placing the YSGs on the Hertzsprung-Russell diagram and comparing them against the evolutionary tracks, we find that new Geneva evolutionary models do an exemplary job at predicting both the locations and the lifetimes of these transitory objects.
Sexual Dysfunction and Cardiac Risk (the Second Princeton Consensus Conference)

Recent studies have highlighted the relation between erectile dysfunction (ED) and cardiovascular disease. In particular, the role of endothelial dysfunction and nitric oxide in ED and atherosclerotic disease has been elucidated. Given the large number of men receiving medical treatment for ED, concerns regarding the risk for sexual activity triggering acute cardiovascular events and potential risks of adverse or unanticipated drug interactions need to be addressed. A risk stratification algorithm was developed by the First Princeton Consensus Panel to evaluate the degree of cardiovascular risk associated with sexual activity for men with varying degrees of cardiovascular disease. Patients were assigned to 3 categories: low, intermediate (including those requiring further evaluation), and high risk. This consensus study from the Second Princeton Consensus Conference corroborates and clarifies the algorithm and emphasizes the importance of risk factor evaluation and management for all patients with ED. The panel reviewed recent safety and drug interaction data for 3 phosphodiesterase (PDE)-5 inhibitors (sildenafil, tadalafil, vardenafil), with emphasis on the safety of these agents in men with ED and concomitant cardiovascular disease. Increasing evidence supports the role of lifestyle intervention in ED, specifically weight loss and increased physical activity, particularly in patients with ED and concomitant cardiovascular disease. Special management recommendations for patients taking PDE-5 inhibitors who present at the emergency department and other emergency medical situations are described. Finally, further research on the role of PDE-5 inhibition in treating patients with other medical or cardiovascular disorders is recommended.
Intramolecular Diels-Alder reactions of siloxacyclopentene constrained trienes.

The synthesis of siloxacyclopentene-constrained trienes 7 and 10 and studies of their IMDA cycloadditions are described. The use of appropriately chosen thermal or Lewis acid conditions allows for cycloadducts 3−6 to be obtained with high levels of diastereoselectivity. These adducts possess trans-relationships between the hydroxyl group and the adjacent ring fusion proton, a stereochemical relationship not previously attainable in IMDA reactions.
Probabilities for jumping fault segment stepovers

[1] Seismic hazard analysis relies heavily on the segmentation of faults. The ability of ruptures to break multiple segments has a big impact on estimated hazard. Current practice for estimating multiple segment breakage relies on panels of experts voting on their opinions for each case. Here, we explore the probability of elastodynamic ruptures jumping segment stepovers in numerical simulations of segmented fault systems. We find a simple functional form for the probability of jumping a segment stepover as a function of stepover distance: an exponential falloff with distance. We suggest this simple parameterization of jumping probabilities, combined with sparse observational data to fix the lengthscale parameter, as a new approach to estimating multisegment earthquake hazard.
Nonlinear quantization effects in the LMS and block LMS adaptive algorithms-a comparison

Digital implementations of the least-mean-square (LMS) and block LMS (BLMS) algorithms are compared with respect to finite word effects. The algorithm stalling phenomenon is studied using Gaussian data models and conditional expectation arguments. It is shown that the BLMS algorithm requires (1/2 log/sub 2/ L-K) fewer bits for the same stalling behavior (L=block length and K lies between 0.2 and 1.0, depending on the precise definition of algorithm stalling). On the other hand, the LMS algorithm requires log/sub 2/ L fewer bits than BLMS for the same level of saturation behavior (transient response) at algorithm initialization. Hence, the LMS algorithm requires (1/2 log/sub 2/ L+K) fewer bits than the BLMS algorithm for the same saturation and stalling effects. >
Counting Nondecreasing Integer Sequences that Lie Below a Barrier

Given a barrier 0 ≤ b0 ≤ b1 ≤ � � � , let f(n) be the number of nondecreasing integer sequences 0 ≤ a0 ≤ a1 ≤ � � � ≤ an for which aj ≤ bj for all 0 ≤ j ≤ n. Known formulae for f(n) include an n × n determinant whose entries are binomial coefficients (Kreweras, 1965) and, in the special case ofbj = rj + s, a short explicit formula (Proctor, 1988, p.320). A relatively easy bivariate recursion, decomposing all sequences according to n and an, leads to a bivariate generating function, then a univariate generating function, then a linear recursion for {f(n)}. Moreover, the coefficients of the bivariate generating function have a probabilistic interpretation, leading to an analytic inequality which is an identity for certain values of its argument.
Evaluating Public Per-Student Subsidies to Low-Cost Private Schools : Regression-Discontinuity Evidence from Pakistan

This study estimates the causal effects of a public per-student subsidy program targeted at low-cost private schools in Pakistan on student enrollment and schooling inputs. Program entry is ultimately conditional on achieving a minimum stipulated student pass rate (cutoff) in a standardized academic test. This mechanism for treatment assignment allows the application of regression-discontinuity (RD) methods to estimate program impacts at the cutoff. Data on two rounds of entry test takers (phase 3 and phase 4) are used. Modeling the entry process of phase-4 test takers as a sharp RD design, the authors find evidence of large positive impacts on the number of students, teachers, classrooms, and blackboards. Modeling the entry process of phase-3 test takers as a partially-fuzzy RD design given treatment crossovers, they do not find evidence of significant program impacts on outcomes of interest. The latter finding is likely due to weak identification arising from a small jump in the probability of treatment at the cutoff.
Syntheses and photophysical properties of fluorescent dibenzofurans, a dibenzothiophene, and carbazoles substituted with benzoxazole and hydroxyl groups to produce excited state intramolecular proton‐transfer

Dibenzofurans, a dibenzothiophene, and carbazoles, each substituted with a 2-benzoxazolyl group as well as an ortho-hydroxyl group, were synthesized to produce fluors with fluorescence due to excited-state intramolecular proton-transfer. The orientations for Friedel-Crafts acylation of 3-methoxydibenzothio-phene and of the analogous carbazole were determined. The fluors displayed absorption peaks in the 330–385 nm region with molar extinction coefficients up to 57,000. Fluorescence quantum efficiencies of 0.17–0.44 were obtained at wavelengths that had peak values from 540–600 nm. The fluors are of potential use as wavelength shifters in scintillating polystyrene fibers.
BASS measurements of currents, waves, stress, and turbulence in the North Sea bottom-boundary layer

Shallow-water-boundary layers are affected by current, waves, bottom topography, and stratification. Precise turbulence measurements through such regions are difficult. A deployment of a BASS (Benthic Acoustic Stress Sensor) tripod in November 1997 in the North Sea in 15 m of water provides a data set to examine turbulent boundary layer models. The deployment spanned both calm and storm sea conditions, had strong tidal currents, the location was uniform horizontally, and the bottom-boundary layer was well mixed in temperature. Estimates of stress derived from the covariance, log-fit, drag-law, and inertial-dissipation method have been compared. The covariance stress estimate had the largest sample to sample scatter, but from theoretical considerations should give the best estimate in stratified flow. The drag-law estimate gave the least sampling variability but suffers from the user having to measure a drag coefficient by some other method. The inertial-dissipation method was more tolerant to sensor misalignment, had the second greatest sampling variability, and could not be used to measure stress during slack tide. Averaging many semidiurnal tidal cycles showed greater tidal asymmetry of the log-fit stress than the covariance or inertial-dissipation stress estimates. Turbulent energy generation and dissipation were measured and balanced individually for the upper two sensors and followed a one-over-height-above-bottom profile.
Low-Mass Binary Induced Outflows from Asymptotic Giant Branch Stars

A significant fraction of planetary nebulae (PNe) and protoplanetary nebulae (PPNe) exhibit aspherical, axisymmetric structures, many of which are highly collimated. The origin of these structures is not entirely understood, however, recent evidence suggests that many observed PNe harbour binary systems, which may play a role in their shaping. In an effort to understand how binaries may produce such asymmetries, we study the effect of low-mass (<0.3M ⊙ ) companions (planets, brown dwarfs and low-mass main-sequence stars) embedded into the envelope of a 3.0-M ⊙ star during three epochs of its evolution [red giant branch, asymptotic giant branch (AGB), interpulse AGB]. We find that common envelope evolution can lead to three qualitatively different consequences: (i) direct ejection of envelope material resulting in a predominately equatorial outflow, (ii) spin-up of the envelope resulting in the possibility of powering an explosive dynamo-driven jet and (iii) tidal shredding of the companion into a disc which facilitates a disc-driven jet. We study how these features depend on the secondary's mass and discuss observational consequences.
SHOULD SHORLTINE RAILROADS UPGRADE THEIR SYSTEMS TO HANDLE HEAVY AXLE LOAD CARS?: A KANSAS CASE STUDY

SHOULD SHORLTINE RAILROADS UPGRADE THEIR SYSTEMS TO HANDLE HEAVY AXLE LOAD CARS? A KANSAS CASE STUDY Michael W. Babcock James Sanderson Economics Department Economics Department Kansas State University Kansas State University Manhattan, Kansas 66506 Manhattan, KS 66506 ph: 785-532-4571 ph: 785-410-2669 fax: 785-532-6919 email: jamessan@ksu.edu email: mwb@ksu.edu September 2004
Relaxation kinetics of excitons in cuprous oxide

Due to a simple band structure, the excitons in cuprous oxide (Cu{sub 2}O) are a model system for kinetic studies. Cuprous oxide appeared to be a host for a Bose-Einstein condensate of excitons, as the excitons showed transient kinetic energy distributions which matched those expected for a Bose gas near the critical density for Bose-Einstein condensation. However, recent absolute measurements of the exciton density made it clear that two-exciton annihilation is limiting the exciton density to far below the quantum density. This paper reconciles the measured exciton density with the observed exciton energy distributions by using a Boltzmann equation approach. We include experimentally determined rates for acoustic- and optical-phonon emission, conversion between exciton spin states, and two-exciton annihiliation, and use recent diffusion-Monte-Carlo estimates of the exciton-exciton elastic scattering cross section. Many experiments intending to produce a dense exciton gas in Cu{sub 2}O used surface photoexcitation, and we found it important to include the resulting spatial inhomogeneities in the model by following the exciton occupation numbers as functions of space as well as momentum and time. A detailed but straightforward numerical integration of the resulting Boltzmann equation does in fact match the experimental results, without the assumption of quantum statistics formore » the excitons.« less
Suzuki−Miyaura, α-Ketone Arylation and Dehalogenation Reactions Catalyzed by a Versatile N-Heterocyclic Carbene−Palladacycle Complex

The activity of the complex (IPr)PdCl(η2-N,C-C12H7NMe2), 1 [IPr = (N,N‘-bis(2,6-diisopropylphenyl)imidazol)-2-ylidene], in the Suzuki−Miyaura cross-coupling reaction involving unactivated aryl chlorides and triflates with arylboronic acids at room temperature in technical grade 2-propanol is described. These conditions allow for the synthesis of di- and tri-ortho-substituted biaryls in very short reaction times. This complex also displays very high activity for α-ketone arylation and dehalogenation reactions of activated and unactivated aryl chlorides.
Training and Search On the Job

The paper studies human capital accumulation over workers’ careers in an on the job search setting with heterogenous firms. In renegotiation proof employment con- tracts, more productive firms provide more training. Both general and specific training induce higher wages within jobs, and with future employers, even conditional on the future employer type. Because matches do not internalize the specific capital loss from employer changes, specific human capital can be over-accumulated, more so in low type firms. While validating the Acemoglu and Pischke (1999) mechanisms, the analysis nevertheless arrives at the opposite conclusion: That increased labor market friction reduces training in equilibrium.
The Metagalactic Ionizing Background: A Crisis in UV Photon Production or Incorrect Galaxy Escape Fractions?

Recent suggestions of a “photon underproduction crisis” (Kollmeier et al. 2014) have generated concern over the intensity and spectrum of ionizing photons in the metagalactic ultraviolet background (UVB). The balance of hydrogen photoionization and recombination determines the opacity of the low-redshift intergalactic medium (IGM). We calibrate the hydrogen photoionization rate (ΓH) by comparing Hubble Space Telescope spectroscopic surveys of the low-redshift column density distribution of H I absorbers and the observed (z < 0.4) mean Lyα flux decrement, DA = (0.014)(1 + z) , to new cosmological simulations. The distribution, f(NHI, z) ≡ dN/d(logNHI)dz, is consistent with an increased UVB that includes contributions from both quasars and galaxies. Our recommended fit, ΓH(z) = (4.6× 10−14 s−1)(1 + z) for 0 < z < 0.47, corresponds to unidirectional LyC photon flux Φ0 ≈ 5700 cm−2 s−1 at z = 0. This flux agrees with observed IGM metal ionization ratios (C III/C IV and Si III/Si IV) and suggests a 25-30% contribution of Lyα absorbers to the cosmic baryon inventory. The primary uncertainties in the low-redshift UVB are the contribution from massive stars in galaxies and the LyC escape fraction (fesc), a highly directional quantity that is difficult to constrain statistically. We suggest that both quasars and low-mass starburst galaxies are important contributors to the ionizing UVB at z < 2. Their additional ionizing flux would resolve any crisis in photon underproduction. Subject headings: cosmological parameters — ultraviolet: galaxies — observations — intergalactic medium — quasars: absorption lines
Signal duration and the time scale dependence of signal integration in biochemical pathways

Background: Signal duration (e.g. the time over which an active signaling intermediate persists) is a key regulator of biological decisions in myriad contexts such as cell growth, proliferation, and developmental lineage commitments. Accompanying differences in signal duration are numerous downstream biological processes that require multiple steps of biochemical regulation. Results: Here we present an analysis that investigates how simple biochemical motifs that involve multiple stages of regulation can be constructed to differentially process signals that persist at different time scales. We compute the dynamic, frequency dependent gain within these networks and resulting power spectra to better understand how biochemical networks can integrate signals at different time scales. We identify topological features of these networks that allow for different frequency dependent signal processing properties. Conclusion: We show that multi-staged cascades are effective in integrating signals of long duration whereas multi-staged cascades that operate in the presence of negative feedback are effective in integrating signals of short duration. Our studies suggest principles for why signal duration in connection with multiple steps of downstream regulation is a ubiquitous motif in biochemical systems.
The effects of anisotropic viscosity on turbulence and heat transport in the intracluster medium

In the intracluster medium (ICM) of galaxy clusters, heat and momentum are transported almost entirely along (but not across) magnetic field lines. We perform the first fully self-consistent Braginskii magnetohydrodynamics (MHD) simulations of galaxy clusters including both of these effects. Specifically, we perform local and global simulations of the magnetothermal instability (MTI) and the heat-flux-driven buoyancy instability (HBI) and assess the effects of viscosity on their saturation and astrophysical implications. We find that viscosity has only a modest effect on the saturation of the MTI. As in previous calculations, we find that the MTI can generate nearly sonic turbulent velocities in the outer parts of galaxy clusters, although viscosity somewhat suppresses the magnetic field amplification. At smaller radii in cool-core clusters, viscosity can decrease the linear growth rates of the HBI. However, it has less of an effect on the HBI’s non-linear saturation, in part because three-dimensional interchange motions (magnetic flux tubes slipping past each other) are not damped by anisotropic viscosity. In global simulations of cool-core clusters, we show that the HBI robustly inhibits radial thermal conduction and thus precipitates a cooling catastrophe. The effects of viscosity are, however, more important for higher entropy clusters. We argue that viscosity can contribute to the global transition of cluster cores from cool-core to non-cool-core states: additional sources of intracluster turbulence, such as can be produced by active galactic nuclei feedback or galactic wakes, suppress the HBI, heating the cluster core by thermal conduction; this makes the ICM more viscous, which slows the growth of the HBI, allowing further conductive heating of the cluster core and a transition to a non-cool-core state.
Fluctuations of the quenched mean of a planar random walk in an i.i.d. random environment with forbidden direction

We consider an i.i.d. random environment with a strong form of transience on the two dimensional integer lattice. Namely, the walk always moves forward in the y-direction. We prove an invariance principle for the quenched expected position of the random walk indexed by its level crossing times. We begin with a variation of the Martingale Central Limit Theorem. The main part of the paper checks the conditions of the theorem for our problem.
Nano-Sim: A Step Wise Equivalent Conductance based Statistical Simulator for Nanotechnology Circuit Design

New nanotechnology based devices are replacing CMOS devices to overcome CMOS technology's scaling limitations. However, many such devices exhibit non-monotonic I-V characteristics and uncertain properties which lead to the negative differential resistance (NDR) problem and the chaotic performance. This paper proposes a new circuit simulation approach that can effectively simulate nanotechnology devices with uncertain input sources and negative differential resistance (NDR) problem. The experimental results show a 20-30 times speedup comparing with existing simulators.
The advantages of using quarterly returns for long-term event studies

The main purpose of this paper is to explore the low power and methodological problems as they continue to plague long-term event study research. We investigate long-term tests (up to 2 years) performed on non-overlapping quarterly time frames as a solution. Components of commonly employed characteristic-based matching processes are examined as the source of low power. Single “best” matching firms don’t statistically match their event firms at the time of the event and are vastly inferior to matching with portfolios. A modified market mean method which uses the securities continuously traded during the calendar event period, is shown to be well specified, have comparable power and avoid the costs of more complex matching methodologies. Contrary to popular perception, increased power derives from the decreased variance in comparison returns; not from an increased covariance between comparison firm returns and event firm returns. The tests are easy to implement, well-specified and have higher power when based on quarterly versus monthly data.
A short route to l-iduronic acid building blocks for the syntheses of heparin-like disaccharides

Abstract The effective preparation of differentially protected l -iduronic acid derivatives, as building blocks for the synthesis of heparin-like oligosaccharides, is described in less than nine steps starting from readily available 1,2- O -isopropylidene-6,3- d -glucuronolactone. The pivaloyl group was used as a permanent protecting group of hydroxyl groups. Two heparin-like disaccharides with different sulfation pattern have been prepared by using these l -iduronic acid building blocks.
A traceless perfluorooctylsulfonyl tag for deoxygenation of phenols under microwave irradiation

The perfluorooctylsulfonyl group is introduced as a traceless tag for solution-phase palladium-catalyzed deoxygenation reactions. The synthetic efficiency is improved by microwave irradiation for reaction and fluorous solid-phase extraction for separation. Further application of this traceless tag for multistep synthesis of substituted hydantoin and pyrimidine is also described.
Learning to set up numerical optimizations of engineering designs

Gradient-based numerical optimization of complex engineering designs offers the promise of rapidly producing better designs. However, such methods generally assume that the objective function and constraint functions are continuous, smooth, and defined everywhere. Unfortunately, realistic simulators tend to violate these assumptions, making optimization unreliable. Several decisions that need to be made in setting up an optimization, such as the choice of a starting prototype, and the choice of a formulation of the search space, can make a difference in how reliable the optimization is. Machine learning can help by making these choices based on the results of previous optimizations. We demonstrate this idea by using machine learning for four parts of the optimization setup problem: selecting a starting prototype from a database of prototypes, synthesizing a new starting prototype, predicting which design goals are achievable, and selecting a formulation of the search space. We use standard tree-induction algorithms (C4.5 and CART). We present results in two realistic engineering domains: racing yachts, and supersonic aircraft. Our experimental results show that using inductive learning to make setup decisions improves both the speed and the reliability of design optimization.
Chemical modification of a highly functionalized taxane. The consequences of an absent bridgehead double bond on oxetane D-ring construction.

An oxetane D-ring has been fused to the framework of the highly functionalized taxane 2. The synthetic route is based on a trimethylsilyl triflate-promoted epoxide-opening step, followed by stereocontrolled, regioreversed oxirane formation and reductive transposition of this intermediate with bis(cyclopentadienyl)titanium(III) chloride. This last key step provides for the convenient implementation of additional hydroxyl groups ultimately conducive to intramolecular SN2 reaction. Tangential features of the route outlined herein include specific rearrangement reactions and a retro-aldol cleavage of ring A.
WDM DEMULTIPLEXING BY USING SURFACE PLASMON POLARITONS

The volume of telecommunications traffic keeps growing at an exponential rate. The optical-communications industry, the linchpin of modern telecommunications, in its quest of keeping up with this growth simply must increase the number of wavelengths in the wavelength-division multiplexing (WDM) configuration. The result of this increase would mean, too, that the number of transmitters and receivers that could be placed on one board would increase as well; hence, the density of their packaging would come to micro- and even nano-scale. At the receiver end, which we will consider in this paper, manufacturers are now able to fabricate an array of photodiodes (PDs) on a single wafer, reducing the size of an individual PD to hundreds of nm. The main obstacle in approaching this scale from a communications link point of view, however, is the diffraction limit. One possible solution to this problem is the use of plasmonics. This paper discusses a possible approach to using surface plasmon polaritons (SPPs) for WDM demultiplexing, presents a possible scheme to implement this approach, and offers our analysis of this scheme along with suggestions for future developments.
Asymmetric Michael addition of α-nitro-ketones using catalytic peptides

Peptide-based catalysts have been developed that promote the asymmetric Michael addition of nitroalkanes. The most effective peptides contain a β-turn structural element as well as a basic histidine and an arylsulfonamide-protected arginine. Excellent yields with enantioselectivities of up to 74% ee have been observed.
Raloxifene improves skeletal properties in an animal model of cystic chronic kidney disease.

Patients with chronic kidney disease (CKD) have an increased risk of fracture. Raloxifene is a mild antiresorptive agent that reduces fracture risk in the general population. Here we assessed the impact of raloxifene on the skeletal properties of animals with progressive CKD. Male Cy/+ rats that develop autosomal dominant cystic kidney disease were treated with either vehicle or raloxifene for five weeks. They were assessed for changes in mineral metabolism and skeletal parameters (microCT, histology, whole-bone mechanics, and material properties). Their normal littermates served as controls. Animals with CKD had significantly higher parathyroid hormone levels compared with normal controls, as well as inferior structural and mechanical skeletal properties. Raloxifene treatment resulted in lower bone remodeling rates and higher cancellous bone volume in the rats with CKD. Although it had little effect on cortical bone geometry, it resulted in higher energy to fracture and modulus of toughness values than vehicle-treated rats with CKD, achieving levels equivalent to normal controls. Animals treated with raloxifene had superior tissue-level mechanical properties as assessed by nanoindentation, and higher collagen D-periodic spacing as assessed by atomic force microscopy. Thus, raloxifene can positively impact whole-bone mechanical properties in CKD through its impact on skeletal material properties.
Worst case stability analysis of switching regulators using the structured singular value

A method to assess the effect of component tolerances on the stability of closed loop switching regulators is given. Use of /spl mu/, the structured singular value, is made which obviates the need for time intensive Monte-Carlo simulation runs and also guarantees the assessment of the worst case condition of the system. Furthermore, through the use of newly developed software routines for /spl mu/, the effect of up to a hundred uncertainties may be taken into account. The analysis procedure entails isolating component value uncertainties from the nominal system and arranging them into a standard /spl Delta/-M structure. Subsequent determination of p for this structure along with the small-gain theorem enables a robustness assessment to be made for the system under study. Two procedures are given which enable reduction of a switching regulator system to /spl Delta/-M form. The first considers uncertainties to exist only in inductor and capacitor values. The other extends the formulation to encompass resistance uncertainties as well. An example is given of a regulator design for which an assessment is made of the allowed component tolerances which guarantees a lower limit of the phase margin. >
The Birch Reduction of Aromatic Compounds

The reduction of aromatic compounds by alkali metals in liquid ammonia represents an important method for the preparation of partially unsaturated six-membered rings. The reaction was discovered by Wooster and Godfrey, but the major development resulted from the efforts of A. J. Birch, and the reaction has since come to bear his name. Although a variety of metals can be used, the most common are sodium and lithium, and, to a lesser extent, potassium. Cosolvents such as ether or tetrahydrofuran (THF) are often used to improve solubility, and weak acids such as alcohols may be employed during the reaction as proton sources. The latter are necessary for the reduction of benzene and its unactivated derivatives. Improvement in experimental procedures by Wilds and Nelson, the application to polynuclear compounds by Huckel and later by Harvey, and the development of methods for the alkylation of the anions generated in this process (i.e., reductive alkylation) have made this reaction an important approach to the synthesis of a wide variety of organic compounds. Keywords: Birch reduction; regiochemistry; mechanisms; stereochemistry; intramolecular effects; polynuclear aromatic compounds; aryl ethers; aromatic ketones; aromatic carboxylic acids; aromatic carboxylic esters; aromatic amides; phenols; aromatic amines; arylsilanes; bond cleavage; dimerization; Benkeser reduction; silylation; electrochemical reductions; catalytic hydrogenation; method comparisons; experimental procedures; scope; limitation
Grothendieck–Lefschetz theorem with base locus

We compute the divisor class group of the general hypersurface Y of a complex projective normal variety X of dimension at least four containing a fixed base locus Z. We deduce that completions of normal local complete intersection domains of finite type over C of dimension ≥ 4 are completions of UFDs of finite type over C.
Coalition-proof supply function equilibria under capacity constraints

Whereas in the absence of capacity constraints the Cournot outcome is the unique coalition-proof supply function equilibrium outcome, the presence of capacity constraints may enlarge the set of equilibrium outcomes. Interestingly, if capacities are sufficiently asymmetric the new equilibrium prices are below the Cournot price. These results have important implications for merger and privatization policies: specifically, capacity divestiture will not necessarily imply lower market prices.