cssi/SciSciGPT-SciSciNet huggingface dataset:
Biomixing by Chemotaxis and Enhancement of Biological Reactions

Many phenomena in biology involve both reactions and chemotaxis. These processes can clearly influence each other, and chemotaxis can play an important role in sustaining and speeding up the reaction. However, to the best of our knowledge, the question of reaction enhancement by chemotaxis has not yet received extensive treatment either analytically or numerically. We consider a model with a single density function involving diffusion, advection, chemotaxis, and absorbing reaction. The model is motivated, in particular, by studies of coral broadcast spawning, where experimental observations of the efficiency of fertilization rates significantly exceed the data obtained from numerical models that do not take chemotaxis (attraction of sperm gametes by a chemical secreted by egg gametes) into account. We prove that in the framework of our model, chemotaxis plays a crucial role. There is a rigid limit to how much the fertilization efficiency can be enhanced if there is no chemotaxis but only advection and dif...
Electrochemistry of Supramolecular Systems.

What is the role of electrochemistry in supramolecular chemistry? On one hand, it provides information on energy and kinetics that is not available with spectroscopic and mass spectrometric techniques; on the other, it can be used to alter the electronic states and thus the interactions between molecules, resulting in new compounds and materials. A typical cyclic voltammogram of the complex shown is depicted on the right; only the first three reductions are presented, although a total of six electrons can be transferred to the bipyridine units sequentially (E in V vs. ferrocene/ferrocenium).
Project selection in NIH: A natural experiment from ARRA

Using a natural experiment in research funding by the National Institutes of Health (NIH) following the American Recovery and Reinvestment Act (ARRA) of 2009, we study the NIH's revealed preference in project selection. We do so by comparing the characteristics of the projects additionally selected for funding due to an unexpected increase in resources under the ARRA with those supported through regular NIH budget. We find that the regular-funded projects are on average of higher quality, as measured by the number of publications per project and the impact of these publications, than ARRA-funded projects. Moreover, compared to ARRA projects, regular projects are more likely to produce highest-impact articles and exhibit greater variance in research output. The output from regular projects also seems more closely fitting the purpose of funding. The differences in project quality are largely explained by observable attributes of the projects and research teams, suggesting that the NIH may use these attributes as cues for discerning underlying project quality. In addition, ARRA projects are more likely than regular projects to involve investigators with past grant experience. Many of these inter-group differences are specific to R01 grants, the largest funding category in the NIH. Overall, these results suggest that the NIH's project selection appears generally in line with its purported mission. In particular, our results contrast starkly with the frequent criticism that the NIH is extremely risk-averse and unwarrantedly favors experienced investigators. We discuss the implications of our findings on the NIH's behavior in project selection.
Urban Chinese Perceptions of Threats from the United States and Japan

Cet article examine dans quelle mesure les Chinois urbains percoivent des menaces en provenance des Etats-Unis et du Japon en fonction des elements suivants : soutien au regime et a l'ideologie officielle ; croyance dans le role de la Chine dans le monde ; confiance dans la capacite de la nation a defendre ses interets et sa securite ; interet porte aux affaires interieures et internationales
Particulate surface waxes of whiteflies: morphology, composition and waxing behaviour

The morphology and lipid composition of wax particles and their application to the body surface of adults were examined in the sweetpotato whitefly, Bemisia tabaci (Gennadius), and the glasshouse whitefly, Trialeurodes vaporariorum (Westwood). The wax particles are extruded from plates found on the abdomen of both species. Their form is determined by the templates (modified microtrichia) from which they are extruded. The emerging ribbons are broken off by rakes on the hind tibiae and applied to the rest of the body in a similar manner for both species. Triacylglycerols comprise 65–75% of the lipid in these particles, with hydrocarbons accounting for 3–7% of the total in B. tabaci and only 0.6-1% in T.vaporariorum. Although distinct compositional differences exist between the species, the hydrocarbons in both are fully saturated and contain n-alkanes and branched molecules having eighteen to forty carbon atoms. Possible roles of these wax particles in reducing water flux, protecting against harmful radiation, and providing a barrier to microorganisms are discussed.
Intermolecular dihydrogen- and hydrogen-bonding interactions in diammonium closo-decahydrodecaborate sesquihydrate.

The asymmetric unit of the title salt, 2NH4+·B10H102−·1.5H2O or (NH4)2B10H10·1.5H2O, (I), contains two B10H102− anions, four NH4+ cations and three water mol­ecules. (I) was converted to the anhydrous compound (NH4)2B10H10, (II), by heating to 343 K and its X-ray powder pattern was obtained. The extended structure of (I) shows two types of hydrogen-bonding interactions (N—H⋯O and O—H⋯O) and two types of dihydrogen-bonding interactions (N—H⋯H—B and O—H⋯H—B). The N—H⋯H—B dihydrogen bonding forms a two-dimensional sheet structure, and hydrogen bonding (N—H⋯O and O—H⋯O) and O—H⋯H—B dihydrogen bonding link the respective sheets to form a three-dimensional polymeric network structure. Compound (II) has been shown to form a polymer with the accompanying loss of H2 at a faster rate than (NH4)2B12H12 and we believe that this is due to the stronger dihydrogen-bonding inter­actions shown in the hydrate (I).
New five-coordinate Ru(II) phosphoramidite complexes and their catalytic activity in propargylic amination reactions

The first five-coordinate, square-pyramidal ruthenium complexes of the general formula [RuCl2(PPh3)2L] have been prepared, where L is a phosphoramidite ligand. The new complexes were employed as catalysts for the amination reactions of propargylic esters (18 h, at room temperature or 45 °C, Cs2CO3) to give propargylic amines in isolated yields up to 94%.
Firm Productivity in Bangladesh Manufacturing Industries

The author studies the determinants of total factor productivity (TFP) for manufacturing firms in Bangladesh using data from a recent survey. She obtains TFP measures by making use of firm-specific deflators for output and inputs. Controlling for industry, location, and year fixed effects, she finds that: (1) firm size and TFP are negatively correlated; (2) firm age and TFP exhibit an inverse-U shaped relationship; (3) TFP improves with the quality of the firm's human capital; (4) global integration improves TFP; (5) firms with research and development activities and quality certifications have higher TFP, while more advanced technologies improve TFP only in the presence of significant absorptive capacity; (6) power supply problems cost firms heavily in terms of TFP losses; and (7) the presence of crime dampens TFP.
'Stochastically More Risk Averse:' A Contextual Theory of Stochastic Discrete Choice Under Risk

Abstract Microeconometric treatments of discrete choice under risk are typically homoscedastic latent variable models. Specifically, choice probabilities are given by preference functional differences (given by expected utility, rank-dependent utility, etc.) embedded in cumulative distribution functions. This approach has a problem: Estimated utility function parameters meant to represent agents’ degree of risk aversion in the sense of Pratt (1964) do not imply a suggested “stochastically more risk averse” relation within such models. A new heteroscedastic model called “contextual utility” remedies this, and estimates in one data set suggest it explains (and especially predicts) as well as or better than other stochastic models.
Secretion of a virus-regulated factor by clonal variants of reticuloendotheliosis virus-transformed hematopoietic cells.

Abstract Reticuloendotheliosis virus (REV-T) is an avian acute leukemia virus which transforms hematopoietic cells which express bursal cell determinants in vivo and in vitro . REV-T-transformed hematopoietic cell lines spontaneously give rise to stable variants that secrete a factor which results in the formation of a halo surrounding colonies formed in soft agar. Expression of this phenotype does not correlate with helper virus production, growth rate or morphology, secretion of immunoglobulin, or the tumorigenic potential of the cells. The secretion of this factor appears to be regulated by the genetic information of REV-T.
Electrokinetic Hydrogen Generation from Liquid Water Microjets

We describe a method for generating molecular hydrogen directly from the charge separation effected via rapid flow of liquid water through a metal orifice, wherein the input energy is the hydrostatic pressure times the volume flow rate. Both electrokinetic currents and hydrogen production rates are shown to follow simple equations derived from the overlap of the fluid velocity gradient and the anisotropic charge distribution resulting from selective adsorption of hydroxide ions to the nozzle surface. Pressure-driven fluid flow shears away charge balancing hydronium ions from the diffuse double layer and carries them out of the aperture. Downstream neutralization of the excess protons at a grounded target electrode produces gaseous hydrogen molecules. The hydrogen production efficiency is currently very low (ca. 10-6) for a single cylindrical jet but can be improved with design changes.
Provable-security analysis of authenticated encryption in Kerberos

Kerberos is a widely deployed network authentication protocol currently being considered for standardisation. Many works have analysed its security, identifying flaws and often suggesting fixes, thus promoting the protocol's evolution. Several recent results present successful, formal methods-based verifications of a significant portion of the current version, v.5 and some even imply security in the computational setting. For these results to hold, encryption in Kerberos should satisfy strong cryptographic security notions. However, prior to the authors' work, none of the encryption schemes currently deployed as part of Kerberos, nor their proposed revisions, were known to provably satisfy such notions. The authors take a close look at Kerberos' encryption, and they confirm that most of the options in the current version provably provide privacy and authenticity, although some require slight modifications which they suggest. The authors' results complement the formal methods-based analysis of Kerberos that justifies its current design.
Bipolar electrosurgery: convention and innovation.

Bipolar electrosurgery is part of the customary gynecologic surgical armamentarium providing isolated thermal effects and blood vessel occlusion. However, end points are not always predictable as hemostasis may require contiguous applications and thermal damage can significantly expand beyond the ta
Transmitting an analog Gaussian source over a Gaussian wiretap channel under SNR mismatch

In this work we study encoding/decoding schemes for the transmission of a discrete time analog Gaussian source over a Gaussian wiretap channel. The intended receiver is assumed to have a certain minimum signal to noise ratio (SNR) and the eavesdropper is assumed to have a strictly lower SNR compared to the intended receiver. For a fixed information leakage rate (I ∊ ) to the eavesdropper, we are interested in minimizing the distortion in source reconstruction at the intended receiver, and we propose joint source channel coding (JSCC) schemes for this setup. For a fixed information leakage rate (I ∊ ) to the eavesdropper, we also show that the schemes considered give a graceful degradation of distortion with SNR under SNR mismatch, i.e., when the actual channel SNR is observed to be different from the design SNR.
Using geometric primitives to calibrate traffic scenes

In this paper, we address the problem of recovering the intrinsic and extrinsic parameters of a camera or a group of cameras in a setting overlooking a traffic scene. Unlike many other settings, conventional camera calibration techniques are not applicable in this case. We present a method that uses certain geometric primitives commonly found in traffic scenes, such as straight and curved lanes, lane markings, and poles in order to recover calibration parameters. We show experimentally that these primitives provide the needed redundancy and are capable of achieving accurate results suitable for most traffic monitoring applications.
An efficient implementation of SELF a dynamically-typed object-oriented language based on prototypes

We have developed and implemented techniques that double the performance of dynamically-typed object-oriented languages. Our SELF implementation runs twice as fast as the fastest Smalltalk implementation, despite SELF's lack of classes and explicit variables.To compensate for the absence of classes, our system uses implementation-level maps to transparently group objects cloned from the same prototype, providing data type information and eliminating the apparent space overhead for prototype-based systems. To compensate for dynamic typing, user-defined control structures, and the lack of explicit variables, our system dynamically compiles multiple versions of a source method, each customized according to its receiver's map. Within each version the type of the receiver is fixed, and thus the compiler can statically bind and inline all messages sent to self. Message splitting and type prediction extract and preserve even more static type information, allowing the compiler to inline many other messages. Inlining dramatically improves performance and eliminates the need to hard-wire low-level methods such as +,==, and ifTrue:.Despite inlining and other optimizations, our system still supports interactive programming environments. The system traverses internal dependency lists to invalidate all compiled methods affected by a programming change. The debugger reconstructs inlined stack frames from compiler-generated debugging information, making inlining invisible to the SELF programmer.
Is extracranial-intracranial bypass surgery effective in certain patients?

Cerebral revascularization can be performed through a variety of extracranial-intracranial (EC-IC) bypass operations, using several different donor and recipient vessels, interposition grafts, and anastomotic techniques. The choice of bypass option is dependent on many factors, including the goals of the operation and the availability and accessibility of paorticular donor and recipient vessels. Potential indications for EC-IC bypass fall into two major categories: (1) flow replacement, in the treatment of complex aneurysms or tumors that require vessel sacrifice and (2) flow augmentation, for treatment of cerebral ischemia. The effectiveness of EC-IC bypass for these indications is reviewed in this article.
Precession of Isolated Neutron Stars. I. Effects of Imperfect Pinning

We consider the precession of isolated neutron stars in which superfluid is not pinned to the stellar crust perfectly. In the case of perfect pinning, Shaham showed that there are no slowly oscillatory, long-lived modes. When the assumption of perfect pinning is relaxed, new modes are found that can be long lived but are expected to be damped rather than oscillatory, unless the drag force on moving superfluid vortex lines has a substantial component perpendicular to the direction of relative motion. The response of a neutron star to external torques, such as the spin-down torque, is also treated. We find that when computing the response of a star to perturbations, assuming perfect coupling of superfluid to normal matter from the start can miss some effects.
A generic distributed broadcast scheme in ad hoc wireless networks

We propose a generic framework for distributed broadcasting in ad hoc wireless networks. The approach is based on selecting a small subset of nodes to form a forward node set to carry out a broadcast process. The status of each node, forward or nonforward, is determined either by the node itself or by other nodes. Node status can be determined at different snapshots of network state along time (called views) without causing problems in broadcast coverage. Therefore, the forward node set can be constructed and maintained through either a proactive process (i.e., "up-to-date") before the broadcast process or a reactive process (i.e., "on-the-fly") during the broadcast process. A sufficient condition, called coverage condition, is given for a node to take the nonforward status. Such a condition can be easily checked locally around the node. Several existing broadcast algorithms can be viewed as special cases of the generic framework with k-hop neighborhood information. A comprehensive comparison among existing algorithms is conducted. Simulation results show that new algorithms, which are more efficient than existing ones, can be derived from the generic framework.
Spacelike strings and jet quenching from a Wilson loop

We investigate stationary string solutions with spacelike worldsheet in a five- dimensional AdS black hole background, and find that there are many branches of such solutions. Using a non-perturbative definition of the jet quenching parameter proposed by Liu et. al., hep-ph/0605178, we take the lightlike limit of these solutions to evaluate the jet quenching parameter in an N = 4 super Yang-Mills thermal bath. We show that this proposed definition gives zero jet quenching parameter, independent of how the lightlike limit is taken. In particular, the minimum-action solution giving the dominant contribution to the Wilson loop has a leading behavior that is linear, rather than quadratic, in the quark separation.
Tensor-product representations for string-net condensed states

We show that general string-net condensed states have a natural representation in terms of tensor product states (TPSs). These TPSs are built from local tensors. They can describe both states with short-range entanglement (such as the symmetry-breaking states) and states with long-range entanglement (such as string-net condensed states with topological/quantum order). The tensor product representation provides a kind of ``mean-field'' description for topologically ordered states and could be a powerful way to study quantum phase transitions between such states. As an attempt in this direction, we show that the constructed TPSs are fixed points under a certain wave-function renormalization-group transformation for quantum states.
Broad wavelength tunability in gain-levered quantum-well semiconductor lasers

The gain-lever effect1,2 in a two-section quantum-well laser leads to a substantial enhancement of the efficiency of direct intensity modulation and frequency modulation (FM) without a corresponding increase in the intensity noise and frequency noise (linewidth).3,4 The large FM response results from the fact that the usual carrier clamping condition for a laser above threshold does not apply (although gain clamping still does) and leads to a very large range of variation in electron density. It has been pointed out that this should lead to a large wavelength tuning range.3 Indeed, it has been recently reported that a distributed-feedback (DFB) strained-quantum-well laser operated in the gain-levered mode can be tuned continuously over a 6.1-nm range at 1530 nm, the largest range reported to date.5 This paper examines the mechanisms responsible for broad wavelength tunability and the conditions necessary to achieve it.
Ionization structure and spectra of iron in gaseous nebulae

The emission spectra and the ionization structure of the low ionization stages of iron, Fe I-Fe IV, in gaseous nebulae are studied. This work includes (i) new atomic data for photoionization cross sections, total e-ion recombination rates, excitation collision strengths, and transition probabilities calculated under the Iron Project by the Ohio State atomic astrophysics group; (ii) detailed study of excitation mechanisms for the [Fe II], [Fe III], and [Fe IV] emission, and spectroscopic analysis of the observed IR, optical, and UV spectra; (iii) study of the physical structure and kinematics of the nebulae and their ionization fronts. Spectral analysis of the well-observed Orion Nebula is carried out as a test case, using extensive collisional-radiative and photoionization models. It is shown that the [Fe II] emission from the Orion Nebula is predominantly excited via electron collisions in high-density partially ionized zones; radiative fluorescence is relatively less effective. Further evidence for high-density zones is derived from the [O I] and [Ni II] spectral lines, as well as from the kinematic measurements of ionic species in the nebula. The ionization structure of iron in Orion is modeled using the newly calculated atomic data and shows some significant differences from previous models. The new model suggests a fully ionized H II region at densities on the order of 103 cm-3 and a dynamic partially ionized H II/H I region at densities of 105-107 cm-3. Photoionization models also indicate that the optical [O I] and [Fe II] emission originates in high-density partially ionized regions within ionization fronts, thereby confirming the general Fe II/O I correlation in H II regions that was determined in earlier studies. The gas-phase iron abundance in Orion is estimated from observed spectra, including recently observed [Fe IV] lines.
Magnetic Thrust Bearing Operation and Industrial Pump Application

Magnetic bearings represent a new bearing technology, which has some advantages over conventional fluid film and rolling element bearings for some applications. The paper describes the basic concepts of magnetic thrust bearing operation involving the magnetic actuator, electronic controls, power amplifier, and sensor. The magnetic actuator is a magnetic circuit, which generates attractive forces. These support the rotating shaft. While it is often thought that magnetic bearings are highly nonlinear devices, this paper demonstrates that they are linear in both the perturbation flux and current when used in a double acting configuration. Electronic feedback controls are used to stabilize the bearing. Example design parameters are presented for an application to an industrial canned motor pump.
Repositories and object oriented databases

A repository is a shared database of information about engineered artifacts. An object-oriented repository has many of the same features as an object-oriented database: properties, relationships, and versioning. However, the two technologies are different for two reasons. First, a repository system has built-in information models, which are database schemas or object models that cover both generic and tool-specific kinds of information. Second, the features of a repository are often more functional than similar features supported by object-oriented databases. This paper is primarily a survey of the latter features, drawing attention to capabilities that distinguish repositories from object-oriented databases.
2-(3-Pyrrolin-1-yl)-1,4-naphthoquinones: Photoactivated Alkylating Agents

The preparation of 2-(3-pyrrolin-1-yl)-1,4-naphthoquinones and a study of their use as photoactivated alkylating agents is reported. The title compounds were easily synthesized by conjugate addition of the corresponding 3-pyrrolines to various naphthoquinones. Upon exposure to ambient room light, the compounds undergo an internal redox reaction to form 2-(pyrrol-1-yl)-1,4-hydroquinones, which are activated for
THE ATOMIC-TO-MOLECULAR TRANSITION IN GALAXIES. I. AN ANALYTIC APPROXIMATION FOR PHOTODISSOCIATION FRONTS IN FINITE CLOUDS

In this series of papers, we study the structure of the atomic-to-molecular transition in the giant atomic-molecular complexes that are the repositories of most molecular gas in galaxies, with the ultimate goal of attaining a better understanding of what determines galaxies' molecular content. Here we derive an approximate analytic solution for the structure of a photodissociation region (PDR) in a cloud of finite size that is bathed in an external dissociating radiation field. Our solution extends previous work, which with few exceptions has been restricted to a one-dimensional treatment of the radiation field. We show that our analytic results compare favorably to exact numerical calculations in the one-dimensional limit. However, our more general geometry provides a more realistic representation than a semi-infinite slab for atomic-molecular complexes exposed to the interstellar radiation field, particularly in environments such as low-metallicity dwarf galaxies, where the curvature and finite size of the atomic envelope cannot be neglected. For clouds that are at least 20% molecular, we obtain analytic expressions for the molecular fraction in terms of properties of the gas and radiation field that are accurate to tens of percent, while for clouds of lower molecular content we obtain upper limits. As a side benefit, our analysis helps to clarify when self-shielding is the dominant process in H2 formation, and under what circumstances shielding by dust makes a significant contribution.
New frontiers for intelligent content-based retrieval

In this paper, we examine emerging frontiers in the evolution of content-based retrieval systems that rely on an intelligent infrastructure. Here, we refer to intelligence as the capabilities of the systems to build and maintain situational or world models, utilize dynamic knowledge representation, exploit context, and leverage advanced reasoning and learning capabilities. We argue that these elements are essential to producing effective systems for retrieving audio-visual content at semantic levels matching those of human perception and cognition. In this paper, we review relevant research on the understanding of human intelligence and construction of intelligent system in the fields of cognitive psychology, artificial intelligence, semiotics, and computer vision. We also discus how some of the principal ideas form these fields lead to new opportunities and capabilities for content-based retrieval systems. Finally, we describe some of our efforts in these directions. In particular, we present MediaNet, a multimedia knowledge presentation framework, and some MPEG-7 description tools that facilitate and enable intelligent content-based retrieval.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Hot Corrosion of Silica

The high-temperature corrosion of bulk silica glass was studied in pure oxygen and in SO3-containing oxygen atmospheres in the presence of liquid sulfate deposits at temperatures of 700° and 1000°C. No reaction and devitrification were observed without Na2SO4 on the surface. The wetting of the silica by the sulfate, the tendency toward basic fluxing, and the crystallization of the silica incrased with the activity of Na2O. The most extensive degradation of vitreous silica occurred by crystallization, and the resulting spalling under basic conditions and thermal cycling at basic conditions were parabolic. This behavior is explained by a model in which the crystallization is controlled by sodium at the glass-crystal interface and its diffusion into the glass. This sodium diffuses into the glass before crystallization and is swept ahead of the crystallization front.
THE SUN'S MERIDIONAL CIRCULATION AND INTERIOR MAGNETIC FIELD

To date, no self-consistent numerical simulation of the solar interior has succeeded in reproducing the observed thinness of the solar tachocline and the persistence of uniform rotation beneath it. Although it is known that the uniform rotation can be explained by the presence of a global-scale confined magnetic field, numerical simulations have thus far failed to produce any solution where such a field remains confined against outward diffusion. We argue that the problem lies in the choice of parameters for which these numerical simulations have been performed. We construct a simple analytical magnetohydrodynamic model of the solar interior and identify several distinct parameter regimes. For realistic solar parameter values, our results are in broad agreement with the tachocline model of Gough & McIntyre. In this regime, meridional flows driven at the base of the convection zone are of sufficient amplitude to hold back the interior magnetic field against diffusion. For the parameter values used in existing numerical simulations, on the other hand, we find that meridional flows are significantly weaker and, we argue, unable to confine the interior field. We propose a method for selecting parameter values in future numerical models.
DETERRENCE AND THE DEATH PENALTY: PARTIAL IDENTIFICATION ANALYSIS USING REPEATED CROSS SECTIONS

Researchers have used repeated cross sectional observations of homicide rates and sanctions to examine the deterrent effect of the adoption and implementation of death penalty statutes. The empirical literature, however, has failed to achieve consensus. A fundamental problem is that the outcomes of counterfactual policies are not observable. Hence, the data alone cannot identify the deterrent effect of capital punishment. This paper asks how research should proceed. We seek to make transparent how assumptions shape inference. We study the identifying power of relatively weak assumptions restricting variation in treatment response across places and time. We perform empirical analysis using state-level data in the United States in 1975 and 1977. The results are findings of partial identification that bound the deterrent effect of capital punishment. Under the weakest restrictions, there is substantial ambiguity: we cannot rule out the possibility that having a death penalty statute substantially increases or decreases homicide. This ambiguity is reduced when we impose stronger assumptions, but inferences are sensitive to the maintained restrictions. Imposing certain assumptions implies that adoption of a death penalty statute increases homicide, but other assumptions imply that the death penalty deters it. Thus, society at large can draw strong conclusions only if there is a consensus favoring particular assumptions. Without such a consensus, data on sanctions and murder rates cannot settle the debate about deterrence. However, data combined with weak assumptions can bound and focus the debate.
W-gravity and generalized Lax equations for (super) Toda theory

Abstract We generalize the Lax pair and Backlund transformations for Toda and N = 1 super Toda equations to the case of arbitrary world-sheet background geometry. We use the fact that the Toda equations express constant curvature conditions, which arise naturally from flatness conditions equivalent to the W-gravity equation of motion.
VARIATION OF STELLAR ENVELOPE CONVECTION AND OVERSHOOT WITH METALLICITY

We examine how metallicity affects convection and overshoot in the superadiabatic layer of main sequence stars. We present results from a grid of three-dimensional radiation hydrodynamic simulations with four metallicities (Z = 0.040, 0.020, 0.010, 0.001), and spanning a range in effective temperature (4950 < T eff < 6230). We show that changing the metallicity alters properties of the convective gas dynamics, and the structure of the superadiabatic layer and atmosphere. Our grid of simulations shows that the amount of superadiabaticity, which tracks the transition from efficient to inefficient convection, is sensitive to changes in metallicity. We find that increasing the metallicity forces the location of the transition region to lower densities and pressures, and results in larger mean and turbulent velocities throughout the superadiabatic region. We also quantify the degree of convective overshoot in the atmosphere, and show that it increases with metallicity as well.
Fractional branes, confinement, and dynamically generated superpotentials

Abstract We examine the effects of instantons in four-dimensional N = 1 supersymmetric gauge theory by including D0-branes in type IIA brane constructions. We examine instanton-generated superpotentials in supersymmetric QCD and find that they are due to a repulsive force between D4-branes bound to D0-branes ending on NS 5-branes. We study situations where instanton effects break supersymmetry such as the Intriligator-Thomas-Izawa-Yangagida model and relate this to a IIA brane construction. We also argue how confinement due to a condensate of fractional instantons manifests itself in super Yang-Mills theory using fractional D0-branes, D4-branes, and NS-strings.
Outcome and Cost Analysis of Scheduled versus Emergency Scleral Buckling Surgery

Background: Retinal detachments are usually considered to be a surgical emergency. However, there are additional risks and costs for unnecessary emergency surgeries. The purpose of this study is to evaluate whether the conventional wisdom for treating all retinal detachments as emergencies needs to be re-examined. Methods: Forty-eight patients who had an emergency scleral buckle and 89 patients who had a scheduled procedure were randomly selected from 884 consecutive patients who had a primary scleral buckling procedure during a 4 1/2-year period. The medical records of each patient were used to obtain detailed information related to prognosis. The visual acuity measurements of each patient, taken 6 months after the procedure, were obtained from the records of the ophthalmologist following the patient. Linear regression analysis was used to compare the final visual outcome for patients who had emergency surgery with patients who had scheduled surgery after taking into account patient factors related to prognosis. Results: Patients selected for emergency surgery had better visual prognoses than scheduled patients but had the same risk of systemic complications and the same extent of detachment if the macula was not involved. None of the 18 patients with an attached macula experienced macular involvement while awaiting scheduled surgery. There were no differences between emergency and scheduled patients in ocular or systemic complications, rate of reattachment, rate of decreased visual acuity after surgery, visual outcome adjusted for prognosis, or, since 1985, length of hospital stay. A greater cost was incurred for the patients having emergency surgery due to difference in pay scales for support personnel. Conclusions: Because the study is not large and the patients were not randomized to treatment, the results are not definitive. However, they suggest that emergency surgery is unnecessary for many patients with a detached retina.
Comparing Numerical Methods for Solving the Competitive Storage Model

This paper compares numerical methods for solving the competitive storage model. Because storage implies a nonnegativity constraint on stocks, the solution methods must be considered carefully. The model is solved using value function iteration and several projection approaches, including parameterised expectations and decision rules approximation. In considering a storage model with convenience yield, in which the inequality constraint is smoothed, perturbation methods are also applied. Parameterised expectations approximation proves to be the most accurate method, whereas perturbation techniques are shown inadequate for solving this highly nonlinear model. The endogenous grid method allows rapid solution if supply is assumed to be inelastic.
A quantitative assessment of the efficiency of the judicial sector in Latin America

Abstract There is a widespread belief throughout Latin America that the judicial sector is not in a position to foster private sector development within a market system. The courts are overburdened and unable to dispose of cases in a timely fashion. As a result, frustrated litigants lose faith in the public justice system's ability to resolve their disputes. This loss of faith, in turn, causes private parties to factor added costs for judicial delay into their private transactions, and these added costs reduce economic activity and retard economic development. Because there are no viable alternative dispute resolution mechanisms in Latin American countries, the region urgently needs an efficient judicial sector to complement the market reforms recently introduced by many governments. An important implication of this observation is that the enhancement of the capability of the courts to satisfy the demand for dispositions is one of the most important, but least noted, aspects of Latin American economic development strategies. First, we report the results of surveys of court-users in several Latin American countries in an effort to identify the causes of dissatisfaction with the courts. Second, we show that simply increasing the amount of financial resources available to the judiciary will not necessarily increase the courts' efficiency. Finally, we look at a large sample of commercial cases in Argentina and Venezuela to identify court-related and litigant-related factors associated to the length of cost-adjusted time to final disposition of court cases. On the basis of this empirical work we identify the most fruitful courses of judicial reform in Latin America.
Scanning Auger and work-function measurements applied to dispenser cathodes

Abstract A method to perform spatially resolved work-function measurements has been developed using a modified scanning Auger microprobe (SAM). The method is based on patches of different work function giving rise to different onsets of secondary electron emission. The combined SAM work-function measurement permits a microscopic correlation of emissive or surface dipole properties with local elemental composition. The system offers a surface spatial resolution of 0.2 μm provided by the focused incident electron beam, and a work function resolution of better than 0.05 eV for most surface features of size ∼ 4.0 μm or larger. Results are presented for elemental samples which served as a test of the work-function mapping ability. Some initial results on dispenser cathode surfaces are also presented.
Application of the Radial Return Method to Compute Stress Increments From Mroz’s Hardening Rule

It is well known in the literature that the isotropic hardening rule in plasticity is not realistic for handling plastic deformation in a simulation of a full sheet-metal forming process including springback. An anisotropic hardening rule proposed by Mroz is more realistic. For an accurate computation of the stress increment for a given strain increment by using Mroz's rule, the conventional subinterval integration takes excessive computing time. This paper proposes the radial return method to compute such stress increment for saving computing time. Two numerical examples show the efficiency of the proposed method. Even for a sheet model with more than 10,000 thin shell elements, the radial return method takes only 40 percent of the overall computing time by the subinterval integration.
Synthesis of Niobium Silicate Molecular Sieves of the MFI Structure: Evidence for Framework Incorporation of the Niobium Ion

A new electron spin resonance (ESR) method to identify incorporation of transition metals into the framework of zeolite molecular sieves is reported. A novel niobium silicate molecular sieve of MFI...
Dynamical mean-field theory from a quantum chemical perspective.

We investigate the dynamical mean-field theory (DMFT) from a quantum chemical perspective. Dynamical mean-field theory offers a formalism to extend quantum chemical methods for finite systems to infinite periodic problems within a local correlation approximation. In addition, quantum chemical techniques can be used to construct new ab initio Hamiltonians and impurity solvers for DMFT. Here, we explore some ways in which these things may be achieved. First, we present an informal overview of dynamical mean-field theory to connect to quantum chemical language. Next, we describe an implementation of dynamical mean-field theory where we start from an ab initio Hartree–Fock Hamiltonian that avoids double counting issues present in many applications of DMFT. We then explore the use of the configuration interaction hierarchy in DMFT as an approximate solver for the impurity problem. We also investigate some numerical issues of convergence within DMFT. Our studies are carried out in the context of the cubic hydrogen model, a simple but challenging test for correlation methods. Finally, we finish with some conclusions for future directions.
On the structure of minimal winning coalitions in simple voting games

According to Coleman’s index of collective power, a decision rule that generates a larger number of winning coalitions imparts the collectivity a higher a priori power to act. By the virtue of the monotonicity conditions, a decision rule is totally characterized by the set of minimal winning coalitions. In this paper, we investigate the structure of the families of minimal winning coalitions corresponding to maximal and proper simple voting games (SVG). We show that if the proper and maximal SVG is swap robust and all the minimal winning coalitions are of the same size, then the SVG is a specific (up to an isomorphism) system. We also provide examples of proper SVGs to show that the number of winning coalitions is not monotone with respect to the intuitively appealing system parameters like the number of blockers, number of non-dummies or the size of the minimal blocking set.
Glycosyl iodides are highly efficient donors under neutral conditions

Abstract Glycosyl iodides have been prepared and subjected to glycosylation under neutral conditions. The reactions are highly efficient, giving α glycosides even with sterically demanding glycosyl acceptors. Glucosyl iodides react with allyl alcohol slowest and require refluxing conditions. Galactosyl iodides are intermediate in reactivity, providing the allyl glycoside in 3 h at room temperature, whereas glycosylation of fucosyl iodides occurs in less than 1 h under similar conditions. The scope and limitations of the reactions were demonstrated with a variety of acceptors, including an anomeric hydroxyl group, to give trehalose analogs. β-Selective glycosylation of glucosyl iodides, in the absence of C-2 participation, could be achieved by simply changing the solvent from benzene to acetonitrile.
A two-dimensional lattice model with exact supersymmetry

Abstract Starting from a simple discrete model which exhibits a supersymmetric invariance we construct a local, interacting, two-dimensional Euclidean lattice theory which also admits an exact supersymmetry. This model is shown to correspond to the Wess-Zumino model with extended N = 2 supersymmetry in the continuum. We have performed dynamical fermion simulations to check the spectrum and supersymmetric Ward identities and find good agreement with theory.
Capillary-driven microfluidic chips with evaporation-induced flow control and dielectrophoretic microbead trapping

This work reports our efforts on developing simple-to-use microfluidic devices for point-of-care diagnostic applications with recent extensions that include the trapping of microbeads using dielectrophoresis (DEP) and the modulation of the liquid flow using integrated microheaters. DEP serves the purpose of trapping microbeads coated with receptors and analytes for detection of a fluorescent signal. The microheater is actuated once the chip is filled by capillarity, creating an evaporation-induced flow tuned according to assay conditions. The chips are composed of a glass substrate patterned with 50-nm-thick Pd electrodes and microfluidic structures made using a 20-μm-thick dry-film resist (DFR). Chips are covered/sealed by low temperature (50°C) lamination of a 50-μm-thick DFR layer having excellent optical and mechanical properties. To separate cleaned and sealed chips from the wafer, we used an effective chip singulation technique which we informally call the “chip-olate” process. In the experimental section, we first studied dielectrophoretic trapping of 10-μm beads for flow rates ranging from 80 pL s−1 to 2.5 nL s−1 that are generated by an external syringe pump. Then, we characterized the embedded microheater in DFR-covered chips. Flow rates as high as 8 nL s−1 were generated by evaporation-induced flow when the heater was biased by 10 V, corresponding to 270-mW power. Finally, DEP-based trapping and fluorescent detection of functionalized beads were demonstrated as the flow was generated by evaporation-induced flow after the microfluidic structures were filled by capillarity.
H-loop histidine catalyzes ATP hydrolysis in the E. coli ABC-transporter HlyB

Adenosine triphosphate (ATP)-binding cassette (ABC) transporters form a family of molecular motor proteins that couple ATP hydrolysis to substrate translocation across cell membranes. Each nucleotide binding domain of ABC-transporters contains a highly conserved H-loop histidine residue, whose precise mechanistic role in motor functions has remained elusive. By using combined quantum mechanical and molecular mechanical (QM/MM) calculations, we showed that the conserved H-loop residue H662 in E. coli HlyB, a bacterial ABC-transporter, can act first as a general acid and then as a general base to facilitate proton transfer in ATP hydrolysis. Without the assistance of H662, direct proton transfer from the lytic water to ATP results in a substantially higher barrier height. Our findings suggest that the essential function of the H-loop residue H662 is to provide a “chemical linchpin” that shuttles protons between reactants through a relay mechanism, thereby catalyzing ATP hydrolysis in HlyB.
Microglandular endocervical hyperplasia and tubal metaplasia : Pitfalls in the diagnosis of adenocarcinoma on cervical smears

The detection of atypical glandular cells of undetermined significance (AGUS) has risen recently due to the use of new endocervical canal sampling devices, in particular the cytobrush. From April 1993–June 1994, a diagnosis of AGUS ranging from adenocarcinoma in situ (AIS) to invasive adenocarcinoma was initially made on cervical smears from 6 women for whom histologic follow-up data were available. The purpose of this study was to determine if benign cervical glandular lesions can be reliably distinguished from adenocarcinoma on cytology. Review of the smears and histologic slides from 3 patients showed microglandular endocervical hyperplasia on cervical cone specimens. Cervical smears from 2 of these patients showed clusters of small-to-medium-sized cells with nuclei containing coarse, granular chromatin and prominent nucleoli. Cytoplasmic vacuoles and engulfment of neutrophils were present, findings suggestive of endometrial adenocarcinoma. The third patient's smear showed clusters of large cells with ample, vacuolated cytoplasm and vesicular nuclei containing prominent nucleoli, findings suggestive of endocervical adenocarcinoma, In 3 cases evaluated by cervical conization, histologic slides showed tubal metaplasia. The cervical smears showed clusters and sheets of cells with round-to-oval-shaped nuclei containing evenly distributed, finely granular chromatin and inconspicuous nucleoli. Pseudoglandular formation was present in 2 cases, a finding suggestive of AIS. Since the cytologic features of microglandular endocervical hyperplasia and tubal metaplasia overlap those of adenocarcinoma, a differential diagnosis is prudent on cytologic smears of AGUS. Diagn. Cytopathol. 16:168–173, 1997. © 1997 Wiley-Liss, Inc.