cssi/SciSciGPT-SciSciNet huggingface dataset:
Enamine-Based Organocatalysis with Proline and Diamines: The Development of Direct Catalytic Asymmetric Aldol, Mannich, Michael, and Diels−Alder Reactions

Enamines and imines have long been recognized as key intermediates in enzyme catalysis, particularly within a class of enzymes organic chemists would very much like to emulate, the aldolases. Here we summarize the contributions of this laboratory to converting enzymatic enamines, and in some cases imines, into a versatile catalytic asymmetric strategy powered by small organic molecules.
MOMENT-BASED INFERENCE WITH STRATIFIED DATA

Many data sets used by economists and other social scientists are collected by stratified sampling. The sampling scheme used to collect the data induces a probability distribution on the observed sample that differs from the target or underlying distribution for which inference is to be made. If this effect is not taken into account, subsequent statistical inference can be seriously biased. This paper shows how to do efficient semiparametric inference in moment restriction models when data from the target population are collected by three widely used sampling schemes: variable probability sampling, multinomial sampling, and standard stratified sampling.
Incentives, wages, and promotions: theory and evidence

I study an incentive problem that has been largely ignored in the agency literature: incentives for repeated (human capital) investment. The optimal contract is very simple but still provides rich implications for incentive and wage structures in large organizations. The empirical evidence is presented using personnel records of health insurance claim processors in a large U.S. insurance company. These processors are white-collar, nonmanagerial, female, service industry workers—a rapidly growing but rarely studied labor group. The empirical findings are consistent with the main features of the optimal contract.
Shrinkwrapping and the taming of hyperbolic 3-manifolds

We introduce a new technique for finding CAT(-1) surfaces in hyperbolic 3-manifolds. We use this to show that a complete hyperbolic 3-manifold with finitely generated fundamental group is geometrically and topologically tame.
Application of a thermal spike model to experimental ion-induced grain growth data

A model of ion-induced grain growth is developed incorporating the irradiation effect concept of thermal spikes. The results of the model predict that for normal grain growth the ion-induced mobility is linearly proportional to the quantity F{sub D}{sup 2}/{Delta}H{sub coh}{sup 3}, where F{sub D} is the ion and recoil energy deposited in nuclear interactions and {triangle}H{sub coh} is the cohesive energy. This linearity is shown to be supported by the data from six of seven previous ion-induced grain growth experiments. The model analysis is combined with the experimental data to determine values of the proportionality constant, {beta}{sub 2GG}, relating the cohesive energy to the activation energy for grain growth. The values are found to span a range, 0.02{le}{beta}{sub 2GG}{le}0.10, which is less than the value previously determined for the thermal spike treatment of ion beam mixing ({beta}{sub IM}=0.014), and therefore consistent with the idea that atom migration across grain boundaries is easier than migration within the lattice. The consistency of results from the analysis of an entirely different phenomenon, adds further credence to the thermal spike treatment of ion-induced grain growth. Finally, it is recommended that additional experiments be performed to further evaluate the model's validity. 16 refs., 1 fig.,more » 2 tabs.« less
Mechanical and Piezoresistive Properties of Graphite-Filled Polyimide Thin Films

The piezoresistive effect of materials is used as the basis for many types of microsensors. Polyimide, a material widely used in microelectronic fabrication, may be made to exhibit this effect by addition of small graphite particles to form a composite material. Polyimide / graphite based piezoresistive films have the advantage of being spin-castable, plasma-processable, highly chemically resistant, and thermally stable up to 400 °C in nitrogen atmospheres. In this work, piezoresistive polyimide films are formed by addition of various amounts (loadings) of graphite particles one micron in diameter or less to DuPont PI-2555 polyimide. Thin films of these materials are spin-cast on silicon wafers, and an in-situ load-deflection measurement technique is used to evaluate the following film properties: piezoresistive coefficient as a function of both strain and graphite loading; Young’s modulus as a function of graphite loading; and residual film stress as a function of graphite loading. The observed piezoresistive coefficient is a strong function of graphite loading, with good piezoresistive properties exhibited in the loading range of 15-25 wt% graphite.
Self-assembly on a cylinder: a model system for understanding the constraint of commensurability

A crystal lattice, when confined to the surface of a cylinder, must have a periodic structure that is commensurate with the cylinder circumference. This constraint can frustrate the system, leading to oblique crystal lattices or to structures with a chiral seam known as a ‘line slip’ phase, neither of which is stable for isotropic particles in equilibrium on flat surfaces. In this study, we use molecular dynamics simulations to find the steady-state structure of spherical particles with short-range repulsion and long-range attraction far below the melting temperature. We vary the range of attraction using the Lennard-Jones and Morse potentials and find that a shorter-range attraction favors the line-slip. We develop a simple model based only on geometry and bond energy to predict when the crystal or line-slip phases should appear, and find reasonable agreement with the simulations. The simplicity of this model allows us to understand the influence of the commensurability constraint, an understanding that might be extended into the more general problem of self-assembling particles in strongly confined spaces.
Ghost cancellation algorithms for MRI images

Ghost cancellation algorithms for restoring magnetic resonance imaging (MRI) images in medical applications are described. The approach is to model the effect of the time delays and the asymmetry of the sinusoidal readout gradient for even and odd lines with two phase functions relating the actual object density to even and odd parts of the observed image. A priori information about the phase functions is exploited in order to estimate the true object density. Examples of applying this ghost cancellation approach to liver and heart images is presented. >
Global Agricultural Trade and the Doha Round: What Are the Implications for North and South?

The next three-year World Trade Organization round has been set in motion by recent negotiations in Doha, Qatar. Among the most contentious issues in that meeting, and probably over the course of the next round, is direct and indirect producer support for agricultural exporters in the North and forgone production, employment, and trading opportunities for farmers in the South. Our results indicate that real commitments to reduce agricultural support in high-income countries will induce substantial changes in world food prices and domestic agricultural rates of return and output and will cause dramatic shifts in agricultural trade patterns. Total trade expands and real output, wages, and incomes in developing countries, especially among the rural poor, increase substantially. In particular, rural incomes in low- and middle-income countries increase by over $60 billion, a figure that comfortably exceeds even the most ambitious goals for increased development assistance and represents a substantial savings to Organization for Economic Cooperation and Development (OECD) taxpayers. At the same time, European Union and Japanese agricultural exports fall sharply and their imports rise. Other OECD countries see more balanced aggregate trade growth, but a number of strategic sectors are still adversely affected. These facts are likely to complicate negotiations in the Doha Round significantly.
Adaptive multiple subtraction using regularized nonstationary regression

Stationary regression is the backbone of seismic data-processing algorithms including match filtering, which is commonly applied for adaptive multiple subtraction. However, the assumption of stationarity is not always adequate for describing seismic signals. I have developed a general method of nonstationary regression and that applies to nonstationary match filtering. The key idea is the use of shaping regularization to constrain the variability of nonstationary regression coefficients. Simple computational experiments demonstrate advantages of shaping regularization over classic Tikhonov's regularization, including a more intuitive selection of parameters and a faster iterative convergence. Using benchmark synthetic data examples, I have successfully applied this method to the problem of adaptive subtraction of multiple reflections.
Efficient one-step Suzuki arylation of unprotected halonucleosides, using water-soluble palladium catalysts.

Modification of nucleosides to give pharmaceutically active compounds, mutagenesis models, and oligonucleotide structural probes continues to be of great interest. The aqueous-phase modification of unprotected halonucleosides is reported herein. Using a catalyst derived from tris(3-sulfonatophenyl)phosphine (TPPTS) and palladium acetate, 8-bromo-2‘-deoxyguanosine (8-BrdG) is coupled with arylboronic acids to give 8-aryl-2‘-deoxyguanosine adducts (8-ArdG) in excellent yield in a 2:1 water:acetonitrile solvent mixture. The TPPTS ligand was found to be superior to water-soluble alkylphosphines for this coupling reaction. The coupling chemistry has been extended to 8-bromo-2‘-deoxyadenosine (8-BrdA) and 5-iodo-2‘-deoxyuridine (5-IdU), as well as the ribonucleosides 8-bromoguanosine and 8-bromoadenosine. Good to excellent yields of arylated adducts are obtained in all cases. With use of tri(4,6-dimethyl-3-sulfonatophenyl)phosphine (TXPTS), the Suzuki coupling of 8-BrdA and 5-IdU can be accomplished in less tha...
Transnational Migration Studies: Past Developments and Future Trends

AbstractThe past two decades have witnessed a sea change in migration scholarship. Most scholars now recognize that many contemporary migrants and their predecessors maintain various kinds of ties to their homelands at the same time that they are incorporated into the countries that receive them. Increasingly, social life takes place across borders, even as the political and cultural salience of nation-state boundaries remains strong. Transnational migration studies has emerged as an inherently interdisciplinary field, made up of scholars around the world, seeking to describe and analyze these dynamics and invent new methodological tools with which to do so. In this review, we offer a short history of theoretical developments, outlining the different ways in which scholars have defined and approached transnational migration. We then summarize what is known about migrant transnationalism in different arenas—economics, politics, the social, the cultural, and the religious. Finally, we discuss methodological...
PION INTERACTIONS IN CHIRAL FIELD THEORIES

We study in various chiral models the pion charge radius, πe3 form factor ratio, π0→γγ amplitude, charge pion polarizabilities, γγ→π0π0 amplitude at low energies and the ππs-wave I=0 scattering length. We find that a quark-level linear sigma approach (also being consistent with tree-level vector meson dominance) is quite compatible with all of the above data.
Stability analysis of M-dimensional asynchronous swarms with a fixed communication topology

Coordinated dynamical swarm behavior occurs when certain types of animals forage for food or try to avoid predators. Analogous behaviors can occur in engineering systems (e.g., in groups of autonomous mobile robots or air vehicles). In this paper, we study a model of an M-dimensional (M/spl ges/2) asynchronous swarm with a fixed communication topology, where each member only communicate with fixed neighbors, to provide conditions under which collision-free convergence can be achieved with finite-size swarm members that have proximity sensors, and neighbor position sensors that only provide delayed position information. Moreover, we give conditions under which an M-dimensional asynchronous mobile swarm with a fixed communication topology following an "edge-leader" can maintain cohesion during movements even in the presence of sensing delays and asynchronism. In addition, the swarm movement flexibility is analyzed. Such stability analysis is of fundamental importance if one wants to understand the coordination mechanisms for groups of autonomous vehicles or robots, where intermember communication channels are less than perfect and collisions must be avoided.
The emergence of sparse spanners and greedy well-separated pair decomposition

A spanner graph on a set of points in ℝd provides shortest paths between any pair of points with lengths at most a constant factor of their Euclidean distance. A spanner with a sparse set of edges is thus a good candidate for network backbones, as in transportation networks and peer-to-peer network overlays. In this paper we investigate new models and aim to interpret why good spanners ‘emerge' in reality, when they are clearly built in pieces by agents with their own interests and the construction is not coordinated. Our main result is to show that the following algorithm generates a (1+e)-spanner with a linear number of edges. In our algorithm, the points build edges at an arbitrary order. A point p will only build an edge pq if there is no existing edge p′q′ with p′ and q′ at distances no more than $\frac{1}{4(1+1/\varepsilon)} \cdot |pq|$ from p, q respectively. Eventually when all points finish checking edges to all other points, the resulted collection of edges forms a sparse spanner as desired. As a side product, the spanner construction implies a greedy algorithm for constructing linear-size well-separated pair decompositions that may be of interest on its own.
Dislocation mobility in two-dimensional Lennard–Jones material

Abstract In seeking to understand at a microscopic level the response of dislocations to stress, we have undertaken to study as completely as possible the simplest case: a single dislocation in a two-dimensional crystal. The intention is that results from this study will be used as input parameters in larger length scale simulations involving many defects. We present atomistic simulations of defect motion in a two-dimensional material consisting of atoms interacting through a modified Lennard–Jones potential. We focus on the regime where the shear stress is smaller than its critical value, where there is a finite energy barrier for the dislocation to hop one lattice spacing. In this regime motion of the dislocation will occur as single hops through thermal activation over the barrier. Accurate knowledge of the barrier height is crucial for obtaining rates of such processes. We have calculated the energy barrier as a function of two components of the stress tensor in a small system, and have obtained good fits to a functional form with only a few adjustable parameters. We examine prefactors, finite temperature and dynamics.
Identities and inequalities for tree entropy

The notion of tree entropy was introduced by the author as a normalized limit of the number of spanning trees in finite graphs, but is defined on random infinite rooted graphs. We give some new expressions for tree entropy; one uses Fuglede–Kadison determinants, while another uses effective resistance. We use the latter to prove that tree entropy respects stochastic domination. We also prove that tree entropy is non-negative in the unweighted case, a special case of which establishes Luck's Determinant Conjecture for Cayley-graph Laplacians. We use techniques from the theory of operators affiliated to von Neumann algebras.
Engine Environmental Effects on Composite Behavior

The NASA Lewis Research Center has conducted a series of programs intended to investigate and develop the application of composite materials to turbojet engines. A significant part of that effort was directed to establishing the impact resistance and defect growth characteristics of composite materials over the wide range of environmental conditions found in commercial turbojet engine operations. Both analytical and empirical efforts are involved. This paper summarizes the experimental programs and the analytical methodology development as well as an evaluation program for the use of composite materials as fan exit guide vanes.
Prosody based co-analysis for continuous recognition of coverbal gestures

Although recognition of natural speech and gestures have been studied extensively, previous attempts at combining them in a unified framework to boost classification were mostly semantically motivated, e.g., keyword-gesture co-occurrence. Such formulations inherit the complexity of natural language processing. This paper presents a Bayesian formulation that uses a phenomenon of gesture and speech articulation for improving accuracy of automatic recognition of continuous coverbal gestures. The prosodic features from the speech signal were co-analyzed with the visual signal to learn the prior probability of co-occurrence of the prominent spoken segments with the particular kinematical phases of gestures. It was found that the above co-analysis helps in detecting and disambiguating small hand movements, which subsequently improves the rate of continuous gesture recognition. The efficacy of the proposed approach was demonstrated on a large database collected front the weather channel broadcast. This formulation opens new avenues for bottom-up frameworks of multimodal integration.
Synthesis of Carbohydrate Mimics: α-1-C-Substituted-deoxymannojirimycins

Abstract Methodology for the construction of diverse α-1- C -substituted-deoxymannojirimycin analogues is reported. The pseudoanomeric carbon-carbon bond was formed using a Suzuki cross-coupling between vinyl bromide 5 , derived biocatalytically from bromobenzene, and an aryl, alkyl, or carbohydrate boron coupling partner. Ozonolysis and stereoselective reduction followed by an intramolecular nucleophilic ring closing served to form the polyhydroxylated piperidine ring. © 1997 Elsevier Science Ltd.
Two-settlement electric power markets with dynamic-price customers

This study will report both analytical and computational testbed findings regarding the effects of retail dynamic-price contracting on power system operations. The key issue under study is the extent to which the introduction of dynamic price contracts for retail consumers affects the efficiency of both retail and wholesale power market operations through changes in price volatility and load profiles at wholesale, and through re-allocations of risk between load-serving entities and retail consumers.
Real wages and monetary policy: A DSGE approach

Purpose – Studies of the cyclical behavior of real wages have identified monetary shocks and examined the response of real wages and output or employment. A finding that real wages are procyclical in response to a positive monetary policy shock is taken as evidence that prices are stickier than wages. The purpose of this paper is to show that factors other than wage and price stickiness affect the response of real wages to a monetary policy shock. Design/methodology/approach – The authors simulate two prominent dynamic stochastic general equilibrium models under a variety of parameter values and examine the cyclicality of the real wage. Findings – The authors offer robust evidence that the real wage response to monetary policy is affected in important ways by properties of the economy other than stickiness of wages and prices, such as the importance of intermediate goods in the production process and the size of key elasticities. Consequently, the authors cannot appropriately infer the relative stickiness...
Solvent-mediated proton transfer in catalysis by carbonic anhydrase.

Considerable attention has been focused on proton transfer through intervening water molecules in complex macromolecules of biological interest, such as bacteriorhodopsin, cytochrome c oxidase, and many others. Proton transfer in catalysis by carbonic anhydrase provides a useful model for the study of the properties of such proton translocations. High-resolution X-ray crystallography in combination with measurements of catalysis have revealed new details of this process. A prominent proton shuttle residue His64 shows evidence of structural mobility, which appears to enhance proton transfer between the active site and bulk solvent. Moreover, the properties of the imidazole side chain of His64, including its conformations and pKa, are finely tuned by surrounding residues of the active-site cavity. The structure of a network of ordered solvent molecules located between His64 and the active site are also sensitive to surrounding residues. These features combine to provide efficient proton-transfer rates as gr...
Cooperative distributed robust control of modular mobile robots with bounded curvature and velocity

A novel motion control system for compliant framed wheeled modular mobile robots (CFMMR) is studied in this paper. This type of wheeled mobile robot uses rigid axles coupled by compliant frame modules to provide both full suspension and enhanced steering capability without additional hardware. The proposed control system is developed by combining a bounded curvature-based kinematic controller and a nonlinear damping dynamic controller. In particular, multiple forms of controller interaction are examined. A two-axle scout CFMMR configuration is used to evaluate the different control structures. Experimental results verify efficient motion control of posture regulation
The Insurance Value of State Tax-and-Transfer Programs

Abstract This paper estimates the total value that individuals derive from their state's tax-and-transfer program, and shows how this value varies by income. The paper decomposes this total value into two components: redistributive value, which is due to predictable changes in income (and family circumstances), and insurance value, which occurs when taxes and transfers compensate for unexpected income shocks. Our approach is a forward-looking one, where we examine income and transfers net of taxes over a 10-year period. We model state taxes (personal income taxes, the EITC, and sales taxes) and state means-tested transfers (AFDC/TANF and Medicaid/SCHIP). The calculations are made using the Panel Study of Income Dynamics and allow for analysis of the role of changes in tax-and-transfer programs, demographics, and income in the value of state net benefits over a period of more than 30 years. We find that the redistributive value of state tax-and-transfer programs sharply declines with income, but that the insurance value is increasing in income. The resulting total value still declines with income, but not nearly as sharply as the redistributive value. Hence, the insurance value mitigates the incentives for mobility that would “undo” state redistributive spending.
Enzyme Activities of Lactic Streptococci and Their Role in Maturation of Cheese: A Review

Abstract Modification of the genome of economically important lactic streptococcal strains is of interest to improve starter cultures and thus the quality of dairy products. To date only limited Information is available about the enzyme potential of mutant as compared with parent strains of lactic streptococci. Initial action of cell-wall associated proteinases on casein and subsequent action of peptidases on peptides are crucial for normal growth and rapid acid production by streptococci in milk. Lactic streptococci used for cheese making contain a complex proteolytic/lipolytic enzyme system that is needed to modify texture and development of flavor in cheese. The mutant strains of lactic streptococci, lactose-negative and proteinase-negative, have higher amino-peptidase and dipeptidase and lower proteinase activities than their parents. Also, esterase and lipase activities of the mutants are greater than those of their parents. Successful propagation of proteinase-negative mutants to a high cell density is made possible by external pH control and use of whey-based media, and so their use in cheese manufacture is feasible. Altering of cell-wall associated proteinases of group N streptococci is important to control development of bitter flavor in cheese. Incorporation of lactose-negative, proteinase-negative mutants into cheese milk as an adjunct source of enzymes has enhanced development of flavor in cheese.
Fan Flow Deflection in Simulated Turbofan Exhaust

Fan flow deflection for jet noise reduction was applied to subscale nozzles simulating the geometry and exhaust conditions of separate-flow turbofan engines. Two types of deflectors were tested, one comprising two pairs of vanes internal to the fan duct and the other consisting of a wedge positioned outside the fan duct. The noise reduction achieved by the vanes was strong in the downward direction and moderate in the sideline direction. The wedge generated significant attenuation in both directions. The acoustic results are consistent with the measured distortion of the mean velocity field. An approach for the treatment ofnonaxisymmetricjets vis-a-vis perceived noise prediction is introduced.
Palladium-Catalyzed Oxidation of Primary and Secondary Allylic and Benzylic Alcohols

An efficient procedure for the oxidation of primary and secondary allylic and benzylic alcohols to aldehydes and ketones, respectively, has been achieved using catalytic Pd(OAc)2 in dimethyl sulfoxide (DMSO) with oxygen gas as the sole reoxidant of the palladium. Secondary substrates show increased reaction rates and improved yields with the addition of 2 equiv of NaHCO3. The reactions are free of acetal/ketal and ester byproducts.
ECONOMIES OF SCOPE AND SCALE EFFICIENCY GAINS DUE TO DIVERSIFICATION

Using a nonparametric linear programming approach, our contribution is to examine if efficiency gains in Western crop production are realized due to diversification and to demonstrate that the diversification efficiency gains realized are a product of economies of scope efficiency gains and scale efficiency gains. The analysis employed cropping sector data for six major crops for the period, 1975-1996. Results indicate efficiency gains are realized due to diversification for all the two-crop combinations.
Convex bodies of constant width and constant brightness

Abstract In 1926 Nakajima (= Matsumura) showed that any convex body in R 3 with constant width, constant brightness, and boundary of class C 2 is a ball. We show that the regularity assumption on the boundary is unnecessary, so that balls are the only convex bodies of constant width and brightness.
The length of an SLE-Monte Carlo studies

The scaling limits of a variety of critical two-dimensional lattice models are equal to the Schramm–Loewner evolution (SLE) for a suitable value of the parameter κ. These lattice models have a natural parametrization of their random curves given by the length of the curve. This parametrization (with suitable scaling) should provide a natural parametrization for the curves in the scaling limit. We conjecture that this parametrization is also given by a type of fractal variation along the curve, and present Monte Carlo simulations to support this conjecture. Then we show by simulations that if this fractal variation is used to parametrize the SLE, then the parametrized curves have the same distribution as the curves in the scaling limit of the lattice models with their natural parametrization.
SYMBOL: a large experimental system exploring major hardware replacement of software

The SYMBOL system is the result of a major developmental effort to increase the functional capability of hardware. Part of the charter of the broad based project was to reexamine the traditional division between hardware and software, to reexamine the respective roles of program instruction and data storage, and to reduce the overall complexity and cost of computing. In order to adequately evaluate the concepts that had been developed it was concluded that an experimental, usable, real system must be built. The SYMBOL system, now operational, is the embodiment of this effort.
FINITE ORDER IMPLICATIONS OF COMMON PRIORS

I characterize the implications of the common prior assumption for finite orders of beliefs about beliefs at a state and show that in finite models, the only such implications are those stemming from the weaker assumption of a common support. More precisely, given any finite N and any finite partitions model where priors have the same support, there is another finite partitions model with common priors that has the same nth order beliefs and knowledge for all n < N.
Cost-effective use of minicomputers to solve structural problems

In the past, large, expensive computers were required to perform most calculations in the aerospace industry. Today, low-cost minicomputers (both 16- and 32-bit) offer significant capability and are finding increased use, particularly for calculations requiring interactive response or interactive display of results. The advent of virtual memory on minicomputers was the turning point. Now minicomputers have operating system and software capabilities often surpassing those of large, mainframe computers. Minicomputers can solve any problems which can be solved by large computers, except those requiring an expensive (but faster) central processing unit (CPU) and more than 64-bit accuracy. Finite-element structural calculations are often one of the biggest challenges to large mainframe computers. This paper shows how even finite-element structural calculations can be solved cost-effectively on a minicomputer.
Proteomics of calcium-signaling components in plants.

Calcium functions as a versatile messenger in mediating responses to hormones, biotic/abiotic stress signals and a variety of developmental cues in plants. The Ca2+-signaling circuit consists of three major “nodes” – generation of a Ca2+-signature in response to a signal, recognition of the signature by Ca2+ sensors and transduction of the signature message to targets that participate in producing signal-specific responses. Molecular genetic and protein–protein interaction approaches together with bioinformatic analysis of the Arabidopsis genome have resulted in identification of a large number of proteins at each “node” – ∼80 at Ca2+ signature, ∼400 sensors and ∼200 targets – that form a myriad of Ca2+ signaling networks in a “mix and match” fashion. In parallel, biochemical, cell biological, genetic and transgenic approaches have unraveled functions and regulatory mechanisms of a few of these components. The emerging paradigm from these studies is that plants have many unique Ca2+ signaling proteins. The presence of a large number of proteins, including several families, at each “node” and potential interaction of several targets by a sensor or vice versa are likely to generate highly complex networks that regulate Ca2+-mediated processes. Therefore, there is a great demand for high-throughput technologies for identification of signaling networks in the “Ca2+-signaling-grid” and their roles in cellular processes. Here we discuss the current status of Ca2+ signaling components, their known functions and potential of emerging high-throughput genomic and proteomic technologies in unraveling complex Ca2+ circuitry.
Gamma-Ray Bursts in the Swift Era

Since the successful launch of NASA's dedicated gamma-ray burst (GRB) mission, Swift, the study of cosmological GRBs has entered a new era. Here I review the rapid observational and theoretical progress in this dynamical research field during the first two-year of the Swift mission, focusing on how observational breakthroughs have revolutionized our understanding of the physical origins of GRBs. Besides summarizing how Swift helps to solve some pre-Swift mysteries, I also list some outstanding problems raised by the Swift observations. An outlook of GRB science in the future, especially in the GLAST era, is briefly discussed.
Conceiving THz Endometrial Ablation:Feasibility, Requirements and Technical Challenges

Shallow-ablation of endometrial lining using microwaves has been traditionally indicated as a minimally invasive treatment option for dysfunctional uterine bleeding (DUB). Known as microwave endometrial ablation (MEA), relevant procedure is used as an alternative to hysterectomy considering its safety, simplicity and effectiveness. In lieu of the prevailing MEA techniques, it is attempted in this study to foresee the possibility of conceiving an alternative and a newer option on endometrial ablation using mm-wave/THz frequencies. Commensurate with this motivated impetus, objectively considered are merits and design issues of using electromagnetic (EM) spectrum of mm-wave/THz region toward optimal conversion of EM energy into a thermal ablative source so that, the basal layer of endometrium can be effectively destroyed in surgical contexts as necessary. Hence, the feasibility of designing appropriate TEA applicators for controlled and safe procedures so as to ablate just the unwanted tissues within a localized zone of energy field is addressed. Lastly, a quantitative analysis on the interaction of THz EM-energy versus the lossy dielectric characteristics of endometrial medium is indicated to model the underlying (THz-energy)-to-(thermal energy) transduction. Relevant prospects of conceiving TEA and the associated pros and cons are identified specific to the prospects of feasibility, requirement considerations and technical challenges.
Fibrous monolithic ceramics

Fibrous monolithic ceramics are an example of a laminate in which a controlled, three-dimensional structure has been introduced on a submillimeter scale. This unique structure allows this all-ceramic material to fail in a nonbrittle manner. Materials have been fabricated and tested with a variety of architectures. The influence on mechanical properties at room temperature and at high temperature of the structure of the constituent phases and the architecture in which they are arranged are discussed. The elastic properties of these materials can be effectively predicted using existing models. These models also can be extended to predict the strength of fibrous monoliths with an arbitrary orientation and architecture. However, the mechanisms that govern the energy absorption capacity of fibrous monoliths are unique, and experimental results do not follow existing models. Energy dissipation occurs through two dominant mechanisms--delamination of the weak interphases and then frictional sliding after cracking occurs. The properties of the constituent phases that maximize energy absorption are discussed. In this article, the authors examine the structure of Si{sub 3}N{sub 4}-BN fibrous monoliths from the submillimeter scale of the crack-deflecting cell-cell boundary features to the nanometer scale of the BN cell boundaries.
Altruism and the Political Economy of Income Taxation

I develop a model in which altruistic agents vote over quadratic income tax schedules. Agents have heterogeneous preferences and productivities, and the model incorporates the incentive effects of taxation. The main result of the paper establishes the existence of a self-confirming majority rule equilibrium in which agents' labor supply decisions are optimal given their tax liabilities and the tax policy is a majority rule equilibrium given the labor supply decisions. In equilibrium the actions by all agents confirm their expectations, but such expectations may be incorrect out of equilibrium. The model generates majority rule voting equilibria that involve progressive taxation.
On the enhancement of the IMF magnitude during 1978–1979

The magnitude of the interplanetary magnetic field (IMF) exhibits an enhancement during 1978 to 1979 relative to all years back to 1963. It is shown that IMF magnitude variations over the 1966 to 1979 period represent the combined effect of variations in both the radial flux density of the IMF and the degree of spiraling of the IMG, consistent with the theoretical model of Parker. The 1978 to 1979 IMF magnitude enhancement is due to an enhancement of radial flux which was in turn related to an increase of magnetic flux leaving solar active regions. It is also shown that during the corotating stream dominated years 1973 to 1976, the IMF was less wound up than during other years, and that 1973 to 1974 were years of enhanced radial flux.
Design of application-specific 3D Networks-on-Chip architectures

The increasing viability of three dimensional (3D) silicon integration technology has opened new opportunities for chip design innovations, including the prospect of extending emerging systems-on-chip (SoC) design paradigms based on networks-on-chip (NoC) interconnection architectures to 3D chip designs. In this paper, we consider the problem of designing application-specific 3D-NoC architectures that are optimized for a given application. We present novel 3D-NoC synthesis algorithms that make use of accurate power and delay models for 3D wiring with through-silicon vias. In particular, we present a very efficient 3D-NoC synthesis algorithm called ripup-reroute-and-router-merging (RRRM), that is based on a rip-up and reroute formulation for routing flows and a router merging procedure for network optimization. Experimental results on 3D-NoC design cases show that our synthesis results can on average achieve a 74% reduction in power consumption and a 17% reduction in hop count over regular 3D mesh implementations and a 52% reduction in power consumption and a 17% reduction in hop count over optimized 3D mesh implementations.
The Infinite Hierarchical Factor Regression Model

We propose a nonparametric Bayesian factor regression model that accounts for uncertainty in the number of factors, and the relationship between factors. To accomplish this, we propose a sparse variant of the Indian Buffet Process and couple this with a hierarchical model over factors, based on Kingman's coalescent. We apply this model to two problems (factor analysis and factor regression) in gene-expression data analysis.
Identifying risk factors for healthcare-associated infections from electronic medical record home address data.

Background: Residential address is a common element in patient electronic medical records. Guidelines from the U.S. Centers for Disease Control and Prevention specify that residence in a nursing home, skilled nursing facility, or hospice within a year prior to a positive culture date is among the criteria for differentiating healthcare-acquired from community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections. Residential addresses may be useful for identifying patients residing in healthcare-associated settings, but methods for categorizing residence type based on electronic medical records have not been widely documented. The aim of this study was to develop a process to assist in differentiating healthcare-associated from community-associated MRSA infections by analyzing patient addresses to determine if residence reported at the time of positive culture was associated with a healthcare facility or other institutional location. Results: We identified 1,232 of the patients (8.24% of the sample) with positive cultures as probable cases of healthcare-associated MRSA based on residential addresses contained in electronic medical records. Combining manual review with linking to institutional address databases improved geocoding rates from 11,870 records (79.37%) to 12,549 records (83.91%). Standardization of patient home address through geocoding increased the number of matches to institutional facilities from 545 (3.64%) to 1,379 (9.22%). Conclusions: Linking patient home address data from electronic medical records to institutional residential databases provides useful information for epidemiologic researchers, infection control practitioners, and clinicians. This information, coupled with other clinical and laboratory data, can be used to inform differentiation of healthcare-acquired from community-acquired infections. The process presented should be extensible with little or no added data costs.
Evidence of abundant purifying selection in humans for recently-acquired regulatory functions

Although only 5% of the human genome is conserved across mammals, a substantially larger portion is biochemically active, raising the question of whether the additional elements evolve neutrally or confer a lineage-specific fitness advantage. To address this question, we integrate human variation information from the 1000 Genomes Project and activity data from the ENCODE Project. A broad range of transcribed and regulatory nonconserved elements show decreased human diversity, suggesting lineage-specific purifying selection. Conversely, conserved elements lacking activity show increased human diversity, suggesting that some recently became nonfunctional. Regulatory elements under human constraint in nonconserved regions were found near color vision and nerve-growth genes, consistent with purifying selection for recently evolved functions. Our results suggest continued turnover in regulatory regions, with at least an additional 4% of the human genome subject to lineage-specific constraint.
Incentives for Procrastinators

We examine how principals should design incentives to induce time-inconsistent procrastinating agents to complete tasks efficiently. Delay is costly to the principal, but the agent faces stochastic costs of completing the task, and efficiency requires waiting when costs are high. If the principal knows the task-cost distribution, she can always achieve first-best efficiency. If the agent has private information, the principal can induce first-best efficiency for time-consistent agents, but often cannot for procrastinators. We show that second-best optimal incentives for procrastinators typically involve an increasing punishment for delay as time passes.
First principles force field for metallic tantalum

We develop a many-body force field (FF) for tantalum based on extensive ab initio quantum mechanical (QM) calculations and illustrate its application with molecular dynamics (MD). As input data to the FF we use ab initio methods (LAPW-GGA) to calculate: (i) the zero temperature equation of state (EOS) of Ta for bcc, fcc, and hcp crystal structures for pressures up to ~500 GPa, and (ii) elastic constants. We use a mixed-basis pseudopotential code to calculate: (iii) volume-relaxed vacancy formation energy also as a function of pressure. In developing the Ta FF we also use previous QM calculations of: (iv) the EOS for the A15 structure; (v) the surface energy bcc (100); (vi) energetics for shear twinning of the bcc crystal. We find that, with appropriate parameters, an embedded atom model FF (denoted as qEAM FF) is able to reproduce all this QM data. We illustrate the use of the qEAM FF with MD to calculate such finite temperature properties as the melting curve up to 300 GPa and thermal expansivity in a wide temperature range. Both our predictions agree well with experimental values.
Linearization Problems for Lie Algebroids and Lie Groupoids

In this survey, we discuss a series of linearization problems — for Poisson structures, Lie algebroids, and Lie groupoids. The last problem involves a conjecture on the structure of proper groupoids. Attempting to prove this by the method of averaging leads to problems concerning almost actions of compact groups and almost invariant submanifolds for compact group actions. The paper ends with a discussion of possible extensions of the convexity theorems for momentum maps of hamiltonian actions of compact groups.
On the representation of sensor faults in fault detection filters

Abstract This paper presents an extension of the well-known Beard-Jones detection filter that permits isolation of sensor faults in a dynamic system to a fixed direction in output space. The method is based on augmenting the system equations by an auxiliary state to represent the dynamic behavior of the sensor fault, and in effect converts the sensor fault into the same form as an actuator fault. The only condition required is observability of the original system.
Neutron Detection via the Cherenkov Effect

We have incorporated neutron-absorbing elements in transparent, nonscintillating glasses and used the Cherenkov effect to convert neutron-induced beta-gamma radiation directly into light. Use of the Cherenkov effect requires glasses with a high index of refraction (to lower the threshold and increase the number of Cherenkov photons) and neutron absorbers resulting in radioactive products emitting high-energy beta or gamma radiation. In this paper, we present a brief description of the requirements for developing efficient Cherenkov-based neutron detectors, show the results of measurements of the response of representative samples to thermal and fast neutron fluxes, and give the results of a calculation of the expected response of a detector to a moderated fission spectrum.
Möglichkeiten des Einsatzes der Chipkarte zur Erhöhung der Sicherheit im Bildschirmtext-System

An ein modernes Bildschirmtext-System (BTX-System) werden hohe Sicherheitsanforderungen gestellt. Diese konnen auf einfache und benutzerfreundliche Weise mit dem Einsatz der Chipkarte erfullt werden. Die Chipkarte ist eine Plastikkarte im Scheckkartenformat mit integriertem Mikroprozessor und Speicher.
Proline Promoted Synthesis of Ring-Fused Homodimers: Self-Condensation of α,β-Unsaturated Aldehydes†

1,2,4-Trisubstituted cyclohexadienals can be prepared synthetically by self-condensation of β-methyl substituted α,β-unsaturated aldehydes. While molecules with this structural scaffold have been observed in nature, the biological roles of these compounds have yet to be thoroughly investigated. Here we investigate the use of l-proline and its derivatives to effect synthesis of these ring-fused homodimers. The scope of this reaction is investigated with different substrates and proline derivatives. Mechanistic hypotheses are put forth supported by NMR and mass spectrometry studies. The method will enable diversification of this scaffold in sufficient quantities for biological investigations.
REPLICATION AT PERIODICALLY CHANGING MULTIPLICITY OF INFECTION PROMOTES STABLE COEXISTENCE OF COMPETING VIRAL POPULATIONS

RNA viruses are widely used to study evolution experimentally. Many standard protocols of virus propagation and competition are done at nominally low multiplicity of infection (m.o.i.), but lead during one passage to two or more rounds of infection, of which the later ones are at high m.o.i. Here, we develop a model of the competition between wild type (wt) and a mutant under a regime of alternating m.o.i. We assume that the mutant is deleterious when it infects cells on its own, but derives a selective advantage when rare and coinfecting with wt, because it can profit from superior protein products created by the wt. We find that, under these assumptions, replication at alternating low and high m.o.i. may lead to the stable coexistence of wt and mutant for a wide range of parameter settings. The predictions of our model are consistent with earlier observations of frequency-dependent selection in vesicular stomatitis virus and human immunodeficiency virus type 1. Our results suggest that frequency-dependent selection may be common in typical evolution experiments with viruses.
Synthesis of oligonucleotides containing an O6-G-alkyl-O6-G interstrand cross-link

Abstract A methodology to synthesize oligonucleotides containing an alkyl interstrand cross-link between the two O6 atoms of deoxyguanosine has been developed. This cross-link is designed to serve as a stable structural mimic of the lesion formed in duplex DNA with the bifunctional alkylating agent hepsulfam. The O6-alkyl coupling is performed via a Mitsunobu reaction between a nucleoside and mono-protected 1,7-heptanediol. Solid-phase oligonucleotide synthesis using a nucleoside bis-phosphoramidite allows for the assembly of the cross-linked duplex. Sufficient quantities of this cross-linked duplex were obtained for various structural and biological investigations.