cssi/SciSciGPT-SciSciNet huggingface dataset:
Generating a Hot Big Bang via a Change in Topology

This letter uses ideas developed recently in semiclassical quantum gravity to argue that many qualitative features of the Hot Big Bang generally assumed in cosmology may be explained by the hypothesis that, interpreted semiclassically, the Universe “tunnelled into being” via a quantum fluctuation from a small (Planck-sized), topologically complex entity to a topolo-gically trivial entity (like a Friedmann Universe) that rapidly grew to a more macroscopic size.
The cascade radical annulation approach to new analogues of camptothecins. Combinatorial synthesis of silatecans and homosilatecans.

: An overview of the cascade radical annulation approach to the camptothecin family of antitumor drugs is presented. This combinatorial synthetic approach involves two key steps: (1) N-propargylation of a lactone/pyridone D/E ring fragment and (2) cascade radical annulation of an A-ring isonitrile to form rings B and C. The synthesis is probably the most flexible and general route to the camptothecin class of molecules. The parallel synthesis of several libraries of silatecan and homosilatecan libraries is summarized. One of the first-generation silatecans, DB-67, is emerging as a serious candidate for cancer chemotherapy.
Superhumps: confronting theory with observation

We review the theory and observations related to the ‘superhump’ precession of eccentric accretion discs in close binary systems. We agree with earlier work, although for different reasons, that the discrepancy between observation and dynamical theory implies that the effect of pressure in the disc cannot be neglected. We extend earlier work that investigates this effect to include the correct expression for the radius at which resonant orbits occur. Using analytic expressions for the accretion disc structure, we derive a relationship between the period excess and mass ratio with the pressure effects included. This is compared to the observed data, recently derived results for detailed integration of the disc equations and the equivalent empirically derived relations and used to predict values for the mass ratio based on measured values of the period excess for 88 systems.
Effect of plasma composition on the interpretation of Faraday rotation

Faraday rotation (FR) is widely used to infer the orientation and strength of magnetic fields in astrophysical plasmas. We first derive exact expressions of FR that are more general than the previous work in allowing for a plasma of arbitrary composition, arbitrary net charge and arbitrary radiation frequency. The latter includes low-frequency regimes where resonances occur and FR changes sign. We then show how the expressions can be used to constrain degeneracies between plasma density, composition and inferred magnetic field strength in astrophysically relevant ion-electron-positron plasmas of unknown positron to electron number density ratio. Electron-positron pairs may be prevalent in the plasma magnetospheres of pulsars, black holes and active galactic nuclei (AGN) jets, but the fraction of positive charge carriers that are protons or positrons has been difficult to determine. FR is sensitive to the plasma composition which may be helpful. A pure neutral electron-positron plasma has negligible FR, and the greater the fraction of positrons the higher the magnetic field strength required to account for the same FR. We consider parameters relevant to AGN jets and clusters to show the degeneracies in field strengths and plasma composition for a given FR measured value as a function of the plasma composition. We point out that these results can be used to constrain the plasma composition if an independent measurement of the magnetic field strength can be combined with the FR measure.
Blockade of poly(ADP-ribose) synthetase inhibits neutrophil recruitment, oxidant generation, and mucosal injury in murine colitis

Abstract Background & Aims: Inflammatory bowel disease is characterized by oxidative and nitrosative stress, leukocyte infiltration, and up-regulation of intercellular adhesion molecule 1 (ICAM-1) expression in the colon. Recent data show that oxidative and nitrosative stress in isolated enterocytes produces DNA single-strand breaks that activate the nuclear enzyme poly(ADP-ribose) synthetase (PARS), resulting in depletion of intracellular energetics and increased paracellular permeability. The aim of the present study was to examine the in vivo relevance of this injury pathway. Methods: Colitis was induced by rectal instillation of trinitrobenzenesulfonic acid (TNBS) in mice with a genetic deficiency of PARS (PARS −/− ) and in wild-type littermates. Results: In wild-type mice, TNBS treatment resulted in colonic erosion and ulceration that was maintained up to 7 days. Neutrophil infiltration (indicated by myeloperoxidase activity in the mucosa) was associated with up-regulation of ICAM-1 and high levels of malondialdehyde and nitrotyrosine. TNBS-treated PARS −/− mice experienced a similar colonic injury that was, however, completely resolved by 6 days. Resolution of the damage was associated with absence of ICAM-1 up-regulation, reduction of neutrophil infiltration, lipid peroxidation, and nitrosative damage. Conclusions: These data show that PARS plays a critical role in colonic inflammation possibly by regulating ICAM-1 expression, neutrophil recruitment, and the subsequent oxidant generation. GASTROENTEROLOGY 1999;116:335-345
Distance-based bias in model-directed optimization of additively decomposable problems

For many optimization problems it is possible to define a distance metric between problem variables that correlates with the likelihood and strength of interactions between the variables. For example, one may define a metric so that the dependencies between variables that are closer to each other with respect to the metric are expected to be stronger than the dependencies between variables that are further apart. The purpose of this paper is to describe a method that combines such a problem-specific distance metric with information mined from probabilistic models obtained in previous runs of estimation of distribution algorithms with the goal of solving future problem instances of similar type with increased speed, accuracy and reliability. While the focus of the paper is on additively decomposable problems and the hierarchical Bayesian optimization algorithm, it should be straightforward to generalize the approach to other model-directed optimization techniques and other problem classes. Compared to other techniques for learning from experience put forward in the past, the proposed technique is both more practical and more broadly applicable.
Is there a need for fuzzy logic

"Is there a need for fuzzy logic?" is an issue which is associated with a long history of spirited discussions and debates. There are many misconceptions about fuzzy logic. Fuzzy logic is not fuzzy. Basically, fuzzy logic is a precise logic of imprecision and approximate reasoning. More specifically, fuzzy logic may be viewed as an attempt at formalization/mechanization of two remarkable human capabilities. First, the capability to converse, reason and make rational decisions in an environment of imprecision, uncertainty, incompleteness of information, conflicting information, partiality of truth and partiality of possibility- in short, in an environment of imperfect information. And second, the capability to perform a wide variety of physical and mental tasks without any measurements and any computations (Zadeh 1999, 2001). In fact, one of the principal contributions of fuzzy logic-a contribution which is widely unrecognized-is its high power of precisiation. Fuzzy logic is much more than a logical system. It has many facets. The principal facets are: logical, fuzzy-set-theoretic, epistemic and relational. Most of the practical applications of fuzzy logic are associated with its relational facet. In this paper, fuzzy logic is viewed in a nonstandard perspective. In this perspective, the cornerstones of fuzzy logic-and its principal distinguishing features-are: graduation, granulation, precisiation and the concept of a generalized constraint.
Mullite for Structural, Electronic, and Optical Applications

Mullite (3AI2O3. 2Si02) is becoming increasingly important in electronic, optical, and high-temperature structural applications. This paper reviews the current state of mullite-related research at a fundamental level, within the framework of phase equilibria, crystal structure, synthesis, processing, and properties. Phase equilibria are discussed in terms of the problems associated with the nucleation kinetics of mullite and the large variations observed in the solid-solution range. The incongruent melting behavior of mullite is now widely accepted. Large variations in the solid solubility from 58 to 76 mot% alumina are related to the ordering/disordering of oxygen vacancies and are strongly coupled with the method of synthesis used to form mullite. Similarly, reaction sequences which lead to the formation of mullite upon heating depend on the spatial scale at which the components are mixed. Mixing at the atomic level is useful for lowtemperature (<lOOO"C) synthesis of mullite but not for low-temperature sintering. In contrast, precursors that are segregated are better suited for lowtemperature (1250" to 1500°C) densification through viscous deformation. Flexural strength and creep resistS M Wiederhorn-contributing editor
Review of Observational Evidence for Dark Matter in the Universe and in upcoming searches for Dark Stars

Over the past decade, a consensus picture has emerged in which roughly a quarter of the universe consists of dark matter. The observational evidence for the existence of dark matter is reviewed: rotation curves of galaxies, weak lensing measurements, hot gas in clusters, primordial nucleosynthesis and microwave background experiments. In addition, a new line of research on Dark Stars is presented, which suggests that the first stars to exist in the universe were powered by dark matter heating rather than by fusion: the observational possibilities of discovering dark matter in this way are discussed.
Local Public Good Provision: Voting, Peer Effects, and Mobility

Abstract Few empirical strategies have been developed that investigate public provision under majority rule while taking explicit account of the constraints implied by mobility of households. The goal of this paper is to improve our understanding of voting in local communities when neighborhood quality depends on peer or neighborhood effects. We develop a new empirical approach which allows us to impose all restrictions that arise from locational equilibrium models with myopic voting simultaneously on the data generating process. We can then analyze how close myopic models come in replicating the main regularities about expenditures, taxes, sorting by income and housing observed in the data. We find that a myopic voting model that incorporates peer effects fits all dimensions of the data reasonably well.
Log-Space constructible universal traversal sequences for cycles of length O( n 4.03 )

The paper presents a simple construction of polynomial length universal traversal sequences for cycles. These universal traversal sequences are log-space (even NC1) constructible and are of length O(n4.03). Our result improves the previously known upper-bound O(n4.76) for log-space constructible universal traversal sequences for cycles.
A FAST PROTEIN STRUCTURE RETRIEVAL SYSTEM USING IMAGE-BASED DISTANCE MATRICES AND MULTIDIMENSIONAL INDEX

Indexing protein tertiary structures has been shown to provide a scalable solution for structure-to-structure comparisons in large protein structure retrieval systems. To conduct similarity searches against 53,356 polypeptide chains in a database with real-time responses, two critical issues must be addressed, information extraction and suitable indexing. In this paper, we apply computer vision techniques to extract the predominant information encoded in each 2D distance matrix, generated from 3D coordinates of protein chains. Distance matrices are capable of representing specific protein structural topologies, and similar proteins will generate similar matrices. Once meaningful features are extracted from distance images, an advanced indexing structure, Entropy Balanced Statistical (EBS) k-d tree, can be utilized to index the multidimensional data. With a limited amount of training data from domain experts, namely structural classification of a subset of available protein chains, we apply various techniques in the pattern recognition field to determine clusters of proteins in the multi-dimensional feature space. Our system is able to recall search results in a ranked order from the protein database in seconds, exhibiting a reasonably high degree of precision.
Minimality, stabilizability, and strong stabilizability of uncertain plants

This paper considers a set of uncertain transfer functions whose numerator and denominators belong to independent polytopes. It shows that i) the members of this set are free from pole-zero cancellations iff all the ratios of numerator edges and denominator edges are free from pole-zero cancellations and the numerator and denominator corners evaluated at a finite number of points satisfy certain phase conditions, ii) the members of this set are free from pole zero cancellations in the closed right half plane, iff all the ratios of numerator edges and denominator edges are free from pole-zero cancellations in the closed right half plane, and the numerator and denominator corners evaluated at a finite number of points satisfy certain phase conditions, and iii) in the strictly proper case, all plants in the set are strongly stabilizable iff all plants avoid pole-zero cancellations in the closed right half plane and all the corner ratios are strongly stabilizable. A counter-example is presented to show that this last result does not extend to biproper plants. >
Magnetic and structural properties of ferromagnetic Fe5PB2 and Fe5SiB2 and effects of Co and Mn substitutions

Crystallographic and magnetic properties of Fe5PB2, Fe4CoPB2, Fe4MnPB2, Fe5SiB2, Fe4CoSiB2, and Fe4MnSiB2 are reported. All adopt the tetragonal Cr5B3 structure-type and are ferromagnetic at room temperature with easy axis of magnetization along the c-axis. The spin reorientation in Fe5SiB2 is observed as an anomaly in the magnetization near 170 K and is suppressed by substitution of Co or Mn for Fe. The silicides are found to generally have larger magnetic moments than the phosphides, but the data suggest smaller magnetic anisotropy in the silicides. Cobalt substitution reduces the Curie temperatures by more than 100 K and ordered magnetic moments by 16%–20%, while manganese substitution has a much smaller effect. This suggests Mn moments align ferromagnetically with the Fe and that Co does not have an ordered moment in these structures. Anisotropic thermal expansion is observed in Fe5PB2 and Fe5SiB2, with negative thermal expansion seen along the c-axis of Fe5SiB2. First principles calculations of the m...
Electric field and tip geometry effects on dielectrophoretic growth of carbon nanotube nanofibrils on scanning probes

Single-wall carbon nanotube (SWNT) nanofibrils were assembled onto a variety of conductive scanning probes including atomic force microscope (AFM) tips and scanning tunnelling microscope (STM) needles using positive dielectrophoresis (DEP). The magnitude of the applied electric field was varied in the range of 1?20?V to investigate its effect on the dimensions of the assembled SWNT nanofibrils. Both length and diameter grew asymptotically as voltage increased from 5 to 18?V. Below 4?V, stable attachment of SWNT nanofibrils could not be achieved due to the relatively weak DEP force versus Brownian motion. At voltages of 20?V and higher, low quality nanofibrils resulted from incorporating large amounts of impurities. For intermediate voltages, optimal nanofibrils were achieved, though pivotal to this assembly is the wetting behaviour upon tip immersion in the SWNT suspension drop. This process was monitored in situ to correlate wetting angle and probe geometry (cone angles and tip height), revealing that probes with narrow cone angles and long shanks are optimal. It is proposed that this results from less wetting of the probe apex, and therefore reduces capillary forces and especially force transients during the nanofibril drawing process. Relatively rigid probes (force constant ?2?N?m?1) exhibited no perceivable cantilever bending upon wetting and de-wetting, resulting in the most stable process control.
Multiproduct Firms and Price-Setting: Theory and Evidence from U.S. Producer Prices

Abstract Using micro-data on U.S. producer prices, we establish three new facts about price setting by multi-product firms. First, firms selling more goods adjust prices more frequently but on average by smaller amounts. Moreover, their fraction of positive price changes is lower and the dispersion of price changes is higher. Second, price changes within firms are substantially synchronized, which plays a dominant role in explaining pricing dynamics. Third, firms selling more goods have greater within-firm synchronization of price changes. A model with trend inflation and firm-specific menu costs where firms are subject to idiosyncratic and aggregate shocks matches the empirical findings.
The effect of deregulation on environmental research by electric utilities

This paper analyzes the impact of deregulation and restructuring on public-interest environmental research conducted by electric utilities in the US from 1990 to 2001. I find that deregulation has had a substantial negative impact on such expenditures, which have declined by 40%. However, restructuring has had no significant impact. In addition, the 1990 Clear Air Act Amendments have adversely affected such expenditures, contrary to the positive impact these regulations had on pollution abatement R&D as shown in the literature. Results also suggest that state and firm characteristics and regulator preferences play a strong role in the conduct of such research.
A formal total synthesis of leucascandrolide A.

A convergent synthesis of the macrocyclic core of the marine macrolide leucascandrolide A has been accomplished.
Activity and transport of antithrombin during acute limb ischemia

Abstract Antithrombin (AT III), a major circulating anticoagulant, may be influenced by ischemia-induced changes in microvascular integrity and contribute to localized hypercoagulability. In a nonheparinized intact canine hindlimb model we determined AT III activity by chromogenic substrate assay (S-2238); coagulation changes with fibrinogen, activated partial thromboplastin time (aPTT), and prothrombin time (PT); and transvascular exchange by lymph-to-plasma total protein concentration ratio. Femoral venous plasma and lymph samples were assayed during 1 hour of steady state (C), 6 or 8 hours of aortoiliac occlusion (I), and 1 or 3 hours of reperfusion (R). Four groups were studied: GI, sham operated (n = 5); GII, moderate ischemia (n = 7), arterial pressure 30% to 45% C, GIII, 6 hours of severe ischemia (n = 7), arterial pressure 5% to 20% C; and GIV, 8 hours of severe ischemia (n = 5), arterial pressure 5% to 20% C. All parameters varied near baseline in the control group and the group with moderate ischemia. Fibrinogen decreased after 3 hours of ischemia in GIII from 218 ± 38 to 175 ± 46 mg/dl (mean ± SEM) and in GIV from 254 ± 39 to 201 ± 44 mg/dl (p J Vasc Surg 1989;9:740–6.)
Adaptive off-time control for variable-frequency, soft-switched flyback converter at light loads

The soft switching of a flyback converter can be achieved by operating the circuit in the critical conduction mode. However, the critical-mode operation at light loads cannot be maintained due to a very high switching frequency and the loss of the output voltage regulation. A control which regulates the output down to the zero load and maintains soft switching at light loads is proposed. The proposed control scheme was implemented in the 380 V/19 V, 65 W flyback DC/DC converter.
Exploration of Fluorine Chemistry at the Multidisciplinary Interface of Chemistry and Biology

Over the last three decades, my engagement in "fluorine chemistry" has evolved substantially because of the multidisciplinary nature of the research programs. I began my research career as a synthetic chemist in organometallic chemistry and homogeneous catalysis directed toward organic synthesis. Then, I was brought into a very unique world of "fluorine chemistry" in the end of 1970s. I started exploring the interface of fluorine chemistry and transition metal homogeneous catalysis first, which was followed by amino acids, peptides, and peptidomimetics for medicinal chemistry. Since then, I have been exploring the interfaces of fluorine chemistry and multidisciplinary fields of research involving medicinal chemistry, chemical biology, cancer biology, and molecular imaging. This perspective intends to cover my fruitful endeavor in the exploration of fluorine chemistry at the multidisciplinary interface of chemistry and biology in a chronological order to show the evolution of my research interest and strategy.
The Serendipity Family of Finite Elements

We give a new, simple, dimension-independent definition of the serendipity finite element family. The shape functions are the span of all monomials which are linear in at least s−r of the variables where s is the degree of the monomial or, equivalently, whose superlinear degree (total degree with respect to variables entering at least quadratically) is at most r. The degrees of freedom are given by moments of degree at most r−2d on each face of dimension d. We establish unisolvence and a geometric decomposition of the space.
Diastereoselective [4+2] Cycloadditions of Acyl Nitroso Compounds

Abstract A highly diastereoselective route to unsaturated amino alcohol derivatives has been developed that features the [4+2] cycloaddition of chiral acyl nitroso compounds to a variety of conjugated dienes; a useful oxidative method for generating acyl nitroso compounds from the corresponding hydroxamic acids under very mild conditions was also discovered.
A simulation study comparing the performance of two RFID protocols

This paper presents a comparison of version 1.0 Protocol Specification for 900MHz Class 0 RFID Tag with that of Class-1 Generation 2 UHF RFID Protocol for Communications at 860 MHz – 960 MHz for large number of tags. Although the Generation 2 protocol has been released for Class 1, it is intended to be used by all classes of RFID tags. Using detailed simulation we compare their performance and security features. If security is a lower priority over speed in cases where one can be sure that the risk of presence of an eavesdropper is low, Class 0 draft protocol should be used as it provides a definite advantage over Generation 2 protocol. In application areas where the risk of consumer identity/privacy theft is high (consumer goods area), Generation 2 provides the security that eliminates the vulnerability of the RFID EPC structure.
Atmospheric heat redistribution on hot jupiters

Infrared light curves of transiting hot Jupiters present a trend in which the atmospheres of the hottest planets are less efficient at redistributing the stellar energy absorbed on their daysides—and thus have a larger day-night temperature contrast—than colder planets. To this day, no predictive atmospheric model has been published that identifies which dynamical mechanisms determine the atmospheric heat redistribution efficiency on tidally locked exoplanets. Here we present a shallow-water model of the atmospheric dynamics on synchronously rotating planets that explains why heat redistribution efficiency drops as stellar insolation rises. Our model shows that planets with weak friction and weak irradiation exhibit a banded zonal flow with minimal day-night temperature differences, while models with strong irradiation and/or strong friction exhibit a day-night flow pattern with order-unity fractional day-night temperature differences. To interpret the model, we develop a scaling theory which shows that the timescale for gravity waves to propagate horizontally over planetary scales, τwave, plays a dominant role in controlling the transition from small to large temperature contrasts. This implies that heat redistribution is governed by a wave-like process, similar to the one responsible for the weak temperature gradients in the Earth's tropics. When atmospheric drag can be neglected, the transition from small to large day-night temperature contrasts occurs when , where τrad is the radiative relaxation time and Ω is the planetary rotation frequency. Alternatively, this transition criterion can be expressed as τrad ~ τvert, where τvert is the timescale for a fluid parcel to move vertically over the difference in day-night thickness. These results subsume the more widely used timescale comparison for estimating heat redistribution efficiency between τrad and the horizontal day-night advection timescale, τadv. Only because τadv ~ τvert for hot Jupiters does the commonly assumed timescale comparison between τrad and τadv yield approximately correct predictions for the heat redistribution efficiency.
The Vector Fixed Point Unit of the Synergistic Processor Element of the Cell Architecture Processor

A vector fixed point unit (FXU) is designed to speed up multi-media processing. The FXU implements SIMD style integer arithmetic and permute operations. The adder, rotator and permute structure enables the use of static circuits only. The FXU was fabricated using IBM 90nm CMOS SOI technology
An Energy-Efficient Biomedical Signal Processing Platform

This paper presents an energy-efficient processing platform for wearable sensor nodes, designed to support diverse biological signals and algorithms. The platform features a 0.5 V-1.0 V 16-bit microcontroller, SRAM, and accelerators for biomedical signal processing. Voltage scaling and block-level power gating allow optimizing energy efficiency under applications of varying complexity. Programmable accelerators support numerous usage scenarios and perform signal processing tasks at 133 to 215× lower energy than the general-purpose CPU. When running complete EEG and EKG applications using both CPU and accelerators, the platform achieves 10.2× and 11.5× energy reduction respectively compared to CPU-only implementations.
A concise synthesis of 1-substituted-2-tetralones by selective diol dehydration leading to ketone transposition

Dehydration of 1-substituted-1,2-tetralindiols with zinc iodide aAorded the corresponding 2-tetralones in excellent yields. This procedure was found to be superior to the more conventional BF3-catalyzed rearrangement of 1-substituted-1,2-epoxytetralins. # 2000 Elsevier Science Ltd. All rights reserved.
Total ear reimplantation in the rabbit utilising microminiature vascular anastomoses

Summary The instrumentation and technique for the anastomosis of vessels less than 1 mm. or 0·040 in. in external diameter is presented. The external ear of a rabbit has been successfully reimplanted utilising such microminiature vascular repairs.
Constant-Factor optimization of quantum adders on 2d quantum architectures

Quantum arithmetic circuits have practical applications in various quantum algorithms. In this paper, we address quantum addition on 2-dimensional nearest-neighbor architectures based on the work presented by Choi and Van Meter (JETC 2012). To this end, we propose new circuit structures for some basic blocks in the adder, and reduce communication overhead by adding concurrency to consecutive blocks and also by parallel execution of expensive Toffoli gates. The proposed optimizations reduce total depth from $140\sqrt n+k_1$ to $92\sqrt n+k_2$ for constants k1,k2 and affect the computation fidelity considerably.
Missing-sensor-fault-tolerant control for SSSC facts device with real-time implementation

Control of power systems relies on the availability and quality of sensor measurements. However, measurements are inevitably subjected to faults caused by sensor failure, broken or bad connections, bad communication, or malfunction of some hardware or software. These faults in turn may cause the failure of power system controllers and consequently severe contingencies in the power system. To avoid such contingencies, this paper presents a sensor evaluation and (missing sensor) restoration scheme (SERS) by using auto-associative neural networks (auto-encoders) and particle swarm optimization (PSO). Based on the SERS, a missing-sensor-fault-tolerant control (MSFTC) is developed for controlling a static synchronous series compensator (SSSC) connected to a power network. This MSFTC improves the reliability, maintainability and survivability of the SSSC and the power network. The effectiveness of the MSFTC is demonstrated by a real-time implementation of an SSSC connected to the IEEE 10-machine 39-bus system on the Real Time Digital Simulator (RTDS) and TMS320C6701 digital signal processor platform. The proposed fault-tolerant control can be readily applied to many existing controllers in power systems.
INEQUALITY AND THE MEASUREMENT OF RESIDENTIAL SEGREGATION BY INCOME IN AMERICAN NEIGHBORHOODS

American metropolitan areas have experienced rising residential segregation by income since 1970. One potential explanation for this change is growing income inequality. However, measures of residential sorting are typically mechanically related to the income distribution, making it difficult to identify the impact of inequality on residential choice. This paper presents a measure of residential segregation by income, the Centile Gap Index (CGI), which is based on income percentiles. Using the CGI, I find that a one standard deviation increase in income inequality raises residential income segregation by 0.4–0.9 standard deviations. Inequality at the top of the distribution is associated with more segregation of the rich, while inequality at the bottom and declines in labor demand for less-skilled men are associated with residential isolation of the poor. Inequality can fully explain the rise in income segregation between 1970 and 2000.
Performance analysis of TLS Web servers

TLS is the protocol of choice for securing today's e-commerce and online transactions but adding TLS to a Web server imposes a significant overhead relative to an insecure Web server on the same platform. We perform a comprehensive study of the performance costs of TLS. Our methodology is to profile TLS Web servers with trace-driven workloads, replace individual components inside TLS with no-ops, and measure the observed increase in server throughput. We estimate the relative costs of each TLS processing stage, identifying the areas for which future optimizations would be worthwhile. Our results show that while the RSA operations represent the largest performance cost in TLS Web servers, they do not solely account for TLS overhead. RSA accelerators are effective for e-commerce site workloads since they experience low TLS session reuse. Accelerators appear to be less effective for sites where all the requests are handled by a TLS server because they have a higher session reuse rate. In this case, investing in a faster CPU might provide a greater boost in performance. Our experiments show that having a second CPU is at least as useful as an RSA accelerator. Our results seem to suggest that, as CPUs become faster, the cryptographic costs of TLS will become dwarfed by the CPU costs of the nonsecurity aspects of a Web server. Optimizations aimed at general purpose Web servers should continue to be a focus of research and would benefit secure Web servers as well.
The room temperature preparation of the 1-chloro-2,2-difluorovinylzinc reagent from HCFC-133a (CF3CH2Cl). The first ambient, high yield, one-flask preparation of α-chloro-β,β-difluorostyrenes

The reaction of LDA (2.0 equiv.) with a THF solution of ZnCl2 (1.0 equiv.) and HCFC-133a (CF3CH2Cl) (1.0 equiv.) at 15–20°C gives a 91% yield of [F2CCClZnCl]. Addition of ArI and Pd(PPh3)4 at rt to 65°C gives 65–85% isolated yields of ArCClCF2. This one-flask procedure provides the first room temperature generation of the 1-chloro-2,2-difluorovinylzinc reagent and the first high yield preparation of α-chloro-β,β-difluorostyrenes from a cheap, readily available industrial precursor.
Flow separation in shear-layer-driven cavities

A study of the shear-layer flow over a range of open-top cavity configurations is reported. Emphasis is placed on the effect that altering the cavity's span length and aspect ratio has on the development of the shear layer. Computational results are obtained using an interactive method which adapts the compressible boundary-layer model for the flow above the cavity and incompressible Navier-Stokes equations within the enclosure. Interaction of this composite model with the outer, inviscid supersonic flow is also considered in one case. The results show that the location of the stagnation points is sensitive primarily to the variation of the span. When the span was fixed and the aspect ratio varied, the shear layer was nearly unaffected except at aspect ratios less than 0.5. Interaction with the outer flow had a smoothing effect on the shape of the dividing streamline, but did not significantly affect the location of the stagnation points. Nomenclature a = speed of sound = ^JyRT 6 = aspect ratio, -HlL cp = specific heat at constant pressure H = height of the cavity h = distance along the cavity's vertical wall measured from the convex corner k = thermal conductivity L = characteristic length M = Mach number, = u/a Pr =Prandtl number, -^cp/k p = pressure R = constant in perfect gas law Re = Reynolds number, =pUL/n T = temperature t = time U — freestream velocity vector u = velocity component in the x direction v = velocity component in the y direction x = Cartesian coordinate parallel to the plate y = Cartesian coordinate normal to the plate 7 = ratio of specific heats, =cp/cv A = small increment, difference <5 = boundary-layer thickness f = vorticity function fj, = viscosity coefficient in the boundary-layer equations p = density \l/ = stream function Subscripts BL = boundary-layer calculation c = cavity calculation e = local outer flow condition R = reference W '=wall
DID THE 65 MPH SPEED LIMIT SAVE LIVES

In 1987, most states raised the speed limit from 55 to 65 mph on portions of their rural interstate highways. There was intense debate about the increase, and numerous evaluations were conducted afterwards. These evaluations share a common problem: they only measure the local effects of the change. But the change must be judged by its system-wide effects. In particular, the new 65 mph limit allowed the state highway patrols to shift their resources from speed enforcement on the interstates to other safety activities and other highways--a shift many highway patrol chiefs had argued for. If the chiefs were correct, the new allocation of patrol resources should lead to a reduction in statewide fatality rates. Similarly, the chance to drive faster on the interstates should attract drivers away from other, more dangerous roads, again generating system-wide consequences. This study measures these changes and obtains surprising results. We find that the 65 mph limit reduced statewide fatality rates by 3.4% to 5.1%, holding constant the effects of long-term trend, driving exposure, seat belt laws, and economic factors.
All-optical modulation of four wave mixing in a Rb-filled hollow-core photonic band-gap fiber

We demonstrate efficient modulation of four-wave mixing in a Rb-waveguide system via application of a weak “switching” field. We observe 3 dB attenuation of the signal field with only 3600 photons of “switching” energy.
Icebergs in the clouds: the other risks of cloud computing

Cloud computing is appealing from management and efficiency perspectives, but brings risks both known and unknown. Well-known and hotly-debated information security risks, due to software vulnerabilities, insider attacks, and side-channels for example, may be only the "tip of the iceberg." As diverse, independently developed cloud services share ever more fluidly and aggressively multiplexed hardware resource pools, unpredictable interactions between load-balancing and other reactive mechanisms could lead to dynamic instabilities or "meltdowns." Non-transparent layering structures, where alternative cloud services may appear independent but share deep, hidden resource dependencies, may create unexpected and potentially catastrophic failure correlations, reminiscent of financial industry crashes. Finally, cloud computing exacerbates already-difficult digital preservation challenges, because only the provider of a cloud-based application or service can archive a "live," functional copy of a cloud artifact and its data for long-term cultural preservation. This paper explores these largely unrecognized risks, making the case that we should study them before our socioeconomic fabric becomes inextricably dependent on a convenient but potentially unstable computing model.
A Laboratory Investigation of Verification and Reputation Formation in a Repeated Joint Investment Setting

This paper describes an experiment in which subjects, acting as division managers, exchanged privately held information before making intrafirm investment decisions. Social efficiency required that managers honestly disclose their private information, but managers had individual incentives to send biased messages. These features of the model created an important role for ex post verification, the main manipulation in the experiment. The matching protocol was also manipulated, using both random and continuous matching of subjects. This second manipulation was intended to examine whether an important institutional attribute — the frequency of interaction — would affect the usefulness of verification. The results of the experiment indicate that verification significantly increased the relative frequency of honest messages and the level of social efficiency. However, the improvements from verification were greater in settings where subjects did not interact repeatedly. The data also indicate that, in the continuous matching treatments, responses depended on the history of behavior of the message sender. However, this behavior was not observed in the random matching treatments. Thus, both the efficacy of verification and the extent of reputation formation depended on the institutional setting.
An Objectives-Driven Process for Selecting Methods to Support Requirements Engineering Activities

This paper presents a framework that guides the requirements engineer in the implementation and execution of an effective requirements generation process. We achieve this goal by providing a well-defined requirements engineering model and a criteria based process for optimizing method selection for attendant activities. Current models address only portions of the requirements process or include activities defined at higher levels of abstraction; this often obscures the implementation aspects of the requirements process. Our model, unlike other models, addresses the complete requirements generation process and consists of activities defined at more adequate levels of abstraction. Additionally, activity objectives are identified and explicitly stated - not implied as in the current models. Activity objectives are crucial as they drive the selection of methods for each activity. Thus, our model guides the requirements engineer through the requirements generation process by providing a clear transition path for requirements through adequately decomposed, well-defined activities. Our model also incorporates a unique approach to verification and validation that enhances quality and reduces the cost of generating requirements. To assist in the selection of methods, we have mapped commonly used methods to activities based on their objectives. In addition, we have identified method selection criteria and prescribed a reduced set of methods that optimize these criteria for each activity defined by our requirements generation process. Thus, the defined approach assists in the task of selecting methods by using selection criteria to reduce a large collection of potential methods to a smaller, manageable set. The model and the set of methods, taken together, provide the much needed guidance for the effective implementation and execution of the requirements generation process
Interstellar dust and extinction

The ultraviolet (UV) region of the spectrum has been crucial in providing information on the nature of the material and size distribution of the particles of interstellar dust. Before there were any measurements of the UV properties of interstellar extinction, interstellar particles were believed to be composed primarily of dirty ices. The maximum of the interstellar extinction was believed to be at 0.3 μm, the shortest wavelength then observable. Both of these predictions were quite wrong (as are probably many of our present ideas regarding dust). The first rocket measurement (Stecher, 1965) showed that there is a very strong extinction feature at 0.22 μm. Now we also know the extinction increases dramatically towards the shortest wavelengths which can be reliably measured to date.
In-Situ Characterization Of Ultra-Small Magnetic Junctions Made By Electrochemical Techniques

Electrochemical impedance spectroscopy is used to characterize the growth of NiO over Ni electrodes. We find a limited increase of thickness and a significant increase of porosity of the oxide as a function of time and anodization potential. Conductance measurements performed on Ni/NiO/Co junctions of 30 nm diameters indicate the presence of a Coulomb blockade at low temperatures and small bias. Tunneling is observed at higher bias. Small magnetoresistance ratios (1%) are found.
Midy's theorem for periodic decimals.

In 1836 E. Midy published at Nantes, France, a pamphlet of twenty-one pages on some topics in number theory with applications to decimals. He was the first to actually prove something about our topic. We formulate our own version, and investigate generalizations, of his main result.
ESR investigations on Ca perovskite

Electron spin resonance studies on fine powders of La0.65Ca0.35MnO3, performed in the X band, are reported. The coexistence of paramagnetic and ferromagnetic phases, in a narrow temperature range close to the Curie temperature, is observed. The electron spin resonance measurements do not support the presence of bipolarons above the Curie temperature. Temperature dependence of the ESR linewidth is governed by the hopping of polarons and the corresponding activation energy is about 150 meV above TC.
MESSENGER observations of magnetopause structure and dynamics at Mercury

[1] On 18 March 2011, MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) became the first spacecraft to orbit Mercury, providing a new opportunity to study the outer boundary of the planet’s magnetosphere—the magnetopause. Here we characterize Mercury’s magnetopause using measurements collected by MESSENGER’s Magnetometer and Fast Imaging Plasma Spectrometer. Analysis of measurements from two of MESSENGER’s “hot seasons,” when the orbital periapsis is on Mercury’s dayside and the magnetopause crossing takes place in the subsolar region, resulted in 43 events with well-determined boundary normals. The typical duration of a magnetopause traversal was ~5 s. The average normal magnetic field component was ~20 nT, and the dimensionless reconnection rate, i.e., the ratio of the normal magnetic field component to the total field magnitude just inside the magnetopause, was 0.15 � 0.02. This rate is a factor of ~3 larger than values found during the most extensive surveys at Earth. The ratio of the reconnection rate at Mercury to that of the Earth is comparable to the ratio of the solar wind Alfven speeds at their respective orbits. We also find that the magnetopause reconnection rate at Mercury is independent of magnetic field shear angle, but it varies inversely with plasma b, the ratio of total thermal pressure to magnetic pressure, in the magnetosheath. These results suggest that reconnectionatMercuryisnotonlymoreintensethanatEarthbutalsothatitoccursfornearly allorientationsofthe interplanetarymagnetic field duetothe low-bnatureof thesolar windin the inner heliosphere.
A mild, convenient, and inexpensive procedure for conversion of vinyl halides to α-haloketones

Treatment of a vinyl chloride with commercially available aqueous sodium hypochlorite solution in a 2:5 mixture of acetic acid/acetone at 0 °C for about 1 h cleanly leads to the corresponding α-chloroketone. Similarly, if a vinyl bromide is exposed to sodium hypobromite (freshly prepared from bromine and sodium hydroxide) at 0 °C in 2:5 acetic acid/acetone as solvent, an α-bromoketone is produced. This methodology has been applied to a number of vinyl chlorides and vinyl bromides, and the transformations generally proceed in high yields. The mild reaction conditions are compatible with a variety of functional groups including amides, esters, and imines.
How Extension Programming Can Provide Useful Input for Land Tenure and Production Decisions: Projected Cost Structures and Decision Support Aids for Texas Coastal Bend Rice Landlords and Producers

The increased contribution of decoupled government payments on rice base acreage has led to a major change in land tenure agreements for rice-producing tenants and landlords in the Texas Coastal Bend. This paper reviews how Extension programming provides information and decision support aids to help both landlords and tenants make sound land tenure arrangements.