cssi/SciSciGPT-SciSciNet huggingface dataset:
Biological formation of pyrroles: nature's logic and enzymatic machinery.

Covering: up to May 2006. This Highlight provides an overview of the molecular logic employed in the formation and elaboration of pyrroles during natural product biosyntheses. The pyrrole ring, either in its unadorned form or as the pyrrole-2-carboxylate moiety commonly encountered in natural products, possesses many useful chemical and electronic features that are readily exploited in biological contexts. The ring itself is planar and electron rich, highly susceptible to electrophilic attack, capable of oxidation and able to participate in both π–π stacking and hydrogen-bonding interactions; the 2-carboxylate moiety provides a nucleophilic center for derivatization, hydrogen bonding and reaction with biological targets. The focus of this Highlight is primarily on the construction of pyrrole rings during secondary metabolite formation, and on their derivatization and incorporation into natural products. Overall biosynthetic strategies are discussed as well as relevant enzymology and mechanistic details.
Outlook vs. Futures: Three Decades of Evidence in Hog and Cattle Markets

The accuracy of hog and cattle price forecasts from four outlook programs is compared with forecasts derived from futures markets. Most of the series begin in the mid to late 1970s and end in 2007. Root mean squared error (RMSE) comparisons indicate the difference between outlook and futures RMSE is relatively small in most cases. In directional terms, outlook forecasts beat futures prices only 2 out of 11 times in hogs, and 1 out of 7 times in cattle. However, the null hypothesis that futures encompasses outlook is rejected in 5 of 11 cases for hogs, and 4 of 7 cases for cattle.
Packet classification using coarse-grained tuple spaces

While the problem of high performance packet classification has received a great deal of attention in recent years, the research community has yet to develop algorithmic methods that can overcome the drawbacks of TCAM-based solutions. This paper introduces a hybrid approach, which partitions the filter set into subsets that are easy to search efficiently. The partitioning strategy groups filters that are close to one another in tuple space [10], which makes it possible to use information from single field lookups to limit the number of subsets that must be searched. We can tradeoff running time against space consumption by adjusting the coarseness of the tuple space partition. We find that for two-dimensional filter sets, the method finds the best- matching filter with just four hash probes while limiting the memory space expansion factor to about 2. We also introduce a novel method for Longest Prefix Matching (LPM), which we use as a component of the overall packet classification algorithm. Our LPM method uses a small amount of on-chip memory to speedup the search of an off-chip data structure, but uses significantly less on-chip memory than earlier methods based on Bloom filters.
Hausdorff distance under translation for points and balls

We study the shape matching problem under the Hausdorff distance and its variants. In the first part of the article, we consider two sets A,B of balls in Rd, d=2,3, and wish to find a translation t that minimizes the Hausdorff distance between A+t, the set of all balls in A shifted by t, and B. We consider several variants of this problem. First, we extend the notion of Hausdorff distance from sets of points to sets of balls, so that each ball has to be matched with the nearest ball in the other set. We also consider the problem in the standard setting, by computing the Hausdorff distance between the unions of the two sets (as point sets). Second, we consider either all possible translations t (as is the standard approach), or consider only translations that keep the balls of A+t disjoint from those of B. We propose several exact and approximation algorithms for these problems. In the second part of the article, we note that the Hausdorff distance is sensitive to outliers, and thus consider two variants that are more robust: the root-mean-square (rms) and the summed Hausdorff distance. We propose efficient approximation algorithms for computing the minimum rms and the minimum summed Hausdorff distances under translation, between two point sets in Rd. In order to obtain a fast algorithm for the summed Hausdorff distance, we propose a deterministic efficient dynamic data structure for maintaining an ϵ-approximation of the 1-median of a set of points in Rd, under insertions and deletions.
Exponential separation in 4{manifolds

We use a new geometric construction, grope splitting, to give a sharp bound for separation of surfaces in 4{manifolds. We also describe applications of this technique in link-homotopy theory, and to the problem of locating 1 {null surfaces in 4{manifolds. In our applications to link-homotopy, grope splitting serves as a geometric substitute for the Milnor group.
Patterns of children's growth in east-central Europe in the eighteenth century.

SummaryRecords in Vienna of the heights of (a) Military Academy youths born between 1730 and 1760, (b) orphanage children born between 1760 and 1780 and (c) military boarding-school children born between 1775 and 1815 have been retrieved and analysed. This constitutes the earliest extant set of measurements of the heights of a group of individuals. Stature was increasing in the late 1740s and decreasing after the 1770s. This evidence indicates a rise and subsequent fall in nutritional status and is consistent with the known pattern of European agricultural conditions in the eighteenth century. Shifts in the age of maximum increment support the notion of the secular changes in the nutritional status of these boys. The stature of the Habsburg boys was greater than the poorest boys of contemporary London but compared unfavourably with the height of the English gentry and American cadets of the nineteenth century and, of course, with the height of today's populations.
Structure-Dependent Oxidative Bromination of Unsaturated C−C Bonds Mediated by Selectfluor

A number of olefins were subjected to oxidative bromination using Selectfluor/KBr. For different types of substrates, addition, monobromine-substituted, or Hunsdiecker-Borodin reaction products can be readily afforded.
No Single Currency Regime Is Right for All Countries or at All Times

This essay considers some prescriptions that are currently popular regarding exchange rate regimes: a general movement toward floating, a general movement toward fixing, or a general movement toward either extreme and away from the middle. The whole spectrum from fixed to floating is covered (including basket pegs, crawling pegs, and bands), with special attention to currency boards and dollarization. One overall theme is that the appropriate exchange rate regime varies depending on the specific circumstances of the country in question (which includes the classic optimum currency area criteria, as well as some newer criteria related to credibility) and depending on the circumstances of the time period in question (which includes the problem of successful exit strategies). Latin American interest rates are seen to be more sensitive to US interest rates when the country has a loose dollar peg than when it has a tight peg. It is also argued that such relevant country characteristics as income correlations and openness can vary over time, and that the optimum currency area criterion is accordingly endogenous.
Geographic routing in d-dimensional spaces with guaranteed delivery and low stretch

Almost all geographic routing protocols have been designed for 2-D. We present a novel geographic routing protocol, named Multihop Delaunay Triangulation (MDT), for 2-D, 3-D, and higher dimensions with these properties: 1) guaranteed delivery for any connected graph of nodes and physical links, and 2) low routing stretch from efficient forwarding of packets out of local minima. The guaranteed delivery property holds for node locations specified by accurate, inaccurate, or arbitrary coordinates. The MDT protocol suite includes a packet forwarding protocol together with protocols for nodes to construct and maintain a distributed MDT for routing. We present the performance of MDT protocols in 3-D and 4-D as well as performance comparisons of MDT routing versus representative geographic routing protocols for nodes in 2-D and 3-D. Experimental results show that MDT provides the lowest routing stretch in the comparisons. Furthermore, MDT protocols are specially designed to handle churn, i.e., dynamic topology changes due to addition and deletion of nodes and links. Experimental results show that MDT's routing success rate is close to 100% during churn, and node states converge quickly to a correct MDT after churn.
JACKKNIFE AND ANALYTICAL BIAS REDUCTION FOR NONLINEAR PANEL MODELS

Fixed effects estimators of panel models can be severely biased because of the well-known incidental parameters problem. We show that this bias can be reduced by using a panel jackknife or an analytical bias correction motivated by large T. We give bias corrections for averages over the fixed effects, as well as model parameters. We find large bias reductions from using these approaches in examples. We consider asymptotics where T grows with n, as an approximation to the properties of the estimators in econometric applications. We show that if T grows at the same rate as n, the fixed effects estimator is asymptotically biased, so that asymptotic confidence intervals are incorrect, but that they are correct for the panel jackknife. We show T growing faster than n 1/3 suffices for correctness of the analytic correction, a property we also conjecture for the jackknife.
Emittance growth, tune shift, and the bunched-beam bunched-beam interaction

It is pointed out that it is important to evaluate and understand both the emittance growth and nature of the tune shift due to multiple beam-beam crossings of bunched beams of heavy ions. Within the Relativistic Heavy Ion Collider, fully stripped /sup 197/Au ions (charge 79e/sup +/) will survive up to 10 h in the collider, with six beam crossings per revolution. With this motivation, the authors have developed a fully relativistic theory of both the average emittance growth and the average tune shift for the bunched-beam bunched-beam interaction that is based on a convolution integral over the densities of the two interpenetrating bunches. In order to calculate this integral, the authors chose to work in a frame where one bunch of the collider is stationary and the other is highly relativistic. This frame has the additional advantage that the microscopic heavy ion interaction becomes perpendicular in nature. In this frame the convolution integral acquires many simplifying and physically interesting features. >
Intermittent Kalman filtering: Eigenvalue cycles and nonuniform sampling

We develop the concept of an eigenvalue cycle to completely characterize the critical erasure probability for intermittent Kalman filtering. It is also proved that eigenvalue cycles can be easily broken if the original physical system is considered to be continuous-time — randomly-dithered nonuniform sampling of observations makes the critical erasure probability depend only on the dominant eigenvalue, making it almost surely equation.
Performance tradeoffs among percolation-based broadcast protocols in wireless sensor networks

Broadcast of information in wireless sensor networks is an important operation, for example, for code updates, queries and membership information. In this paper, we analyse and experimentally compare the performance of vanilla versions of several well-known broadcast mechanisms: flooding, site percolation, bond percolation and modified bond percolation. While flooding and some percolation-based approaches have been compared in the literature, there is no all-to-all comparison among all schemes. We carry out our comparison for several network topologies defined by node locations: random, grid and clustered. Our analysis is performed at the link layer level, where we use a propagation model based on real experiments from the literature. The link model used is independent of the medium access control (MAC) layer and, therefore, helps us in arriving at the best possible values for the metrics that we compare in our analysis. Our main metrics are bandwidth, energy usage and broadcast latency. Our analytical and experimental results show that, given a desired high reliability for all topologies, flooding has the lowest latency but consumes the most energy per broadcast. For dense networks, site percolation achieves comparable latency and reliability to flooding, while lowering energy consumption. Modified bond percolation further lowers energy consumption compared to site percolation, while basic bond percolation leads to a latency increase. For sparse networks, results are similar to a dense network except that site percolation consumes lower energy than modified bond percolation. We briefly discuss implications for different broadcast applications.
Environmental inspection proclivity and state manufacturing growth: the US Experience from the 1990s

In this paper, we construct a ranking of states based on their proclivity to inspect facilities for environmental compliance. Our measure utilizes state-level inspections data supplied by the US Environmental Protection Agency. After developing our ranking, we use it to predict state-level growth in manufacturing establishments. In doing so, we find support for the notion that enforcement intensity adversely impacts such growth. Our results offer insight into why existing studies that examine the impact of environmental regulation on location and growth produce inconsistent results.
Evidence of Wave Damping at Low Heights in a Polar Coronal Hole

We have measured the widths of spectral lines from a polar coronal hole using the Extreme Ultraviolet Imaging Spectrometer on board Hinode. Polar coronal holes are regions of open magnetic field and the source of the fast solar wind. We find that the line widths decrease at relatively low heights. Previous observations have attributed such decreases to systematic effects, but we find that such effects are too small to explain our results. We conclude that the line narrowing is real. The non-thermal line widths are believed to be proportional to the amplitude of Alfven waves propagating along these open field lines. Our results suggest that Alfven waves are damped at unexpectedly low heights in a polar coronal hole. We derive an estimate on the upper limit for the energy dissipated between 1.1 R ☉ and 1.3 R ☉ and find that it is enough to account for up to 70% of that required to heat the polar coronal hole and accelerate the solar wind.
Open-loop HIRF experiments performed on a fault tolerant flight control computer

During the third quarter of 1996, the Closed-Loop Systems Laboratory was established at the NASA Langley Research Center (LaRC) to study the effects of High Intensity Radiated Fields on complex avionic systems and control system components. This new facility provided a link and expanded upon the existing capabilities of the High Intensity Radiated Fields Laboratory at LaRC that were constructed and certified during 1995-96. The scope of the Closed-Loop Systems Laboratory is to place highly integrated avionics instrumentation into a high intensity radiated field environment, interface the avionics to a real-time flight simulation that incorporates aircraft dynamics, engines, sensors, actuators and atmospheric turbulence, and collect, analyze, and model aircraft performance. This paper describes the layout and functionality of the Closed-Loop Systems Laboratory, and the open-loop calibration experiments that led up to the commencement of closed-loop real-time flight experiments.
Layer-by-layer printing of cells and its application to tissue engineering

Tissues and organs exhibit distinct shapes and functions nurtured by vascular connectivity. In order to mimic and examine these intricate structure-function relationships, it is necessary to develop efficient strategies for assembling tissue-like constructs. Many of the top-down fabrication techniques used to build microelectromechanical systems, including photolithography, are attractive due to the similar feature sizes, but are not suitable for delicate biological systems or aqueous environments. A layer-by layer approach has been proposed by us to pattern functional cell structures in three dimensions. Freeform cell structures are created by the inkjet method, in which cells are entrapped within hydrogels and crosslinked on demand. The cells are viable, functional and show potential for cell maturation as exemplified by the diversion of hematopoietic stem cells into multiple cell types. These results show promise for many tissue engineering applications.
Effect of high-viscosity interphases on drainage between hydrophilic surfaces.

Drainage of water from the region between an advancing probe tip and a flat sample is reconsidered under the assumption that the tip and sample surfaces are both coated by a thin water 'interphase' (of width {approx}a few nm) whose viscosity is much higher than the bulk liquid's. A formula derived by solving the Navier-Stokes equations allows one to extract an interphase viscosity of {approx}59 KPa-sec (or {approx}6.6x10{sup 7} times the viscosity of bulk water at 25C) from Interfacial Force Microscope measurements with both tip and sample functionalized hydrophilic by OH-terminated tri(ethylene glycol) undecylthiol, self-assembled monolayers.
Impact of Bayesian Learning and Externalities on Strategic Investment

We investigate the interplay between learning effects and externalities in the problem of competitive investments with uncertain returns. We examine a game theoretic duopoly investment model in which (i) a firm can learn about the profitability of the investment by observing the performance of the first mover and (ii) externalities exist between the investments of two firms. We find a region of a war of attrition between the two firms in which the interplay between externalities and learning gives rise to counterintuitive effects on investment strategies and payoffs. In particular, we find that, contrary to the conventional war of attrition where an increase in benefits for the follower generally delays the first move, an increase in the rate of learning—which tends to benefit the follower—can hasten the first investment. This paper was accepted by James Smith, decision analysis.
Galaxy motions, turbulence and conduction in clusters of galaxies

Unopposed radiative cooling in clusters of galaxies results in excessive mass deposition rates on to the central brightest cluster galaxy. However, the cool cores of galaxy clusters are continuously heated by thermal conduction and turbulent heat diffusion due to minor mergers or the galaxies orbiting the cluster centre. These processes can either reduce the energy requirements for active galactic nucleus heating of cool cores, or they can prevent overcooling altogether. We perform three-dimensional magnetohydrodynamics simulations including field-aligned thermal conduction and self-gravitating particles to model this in detail. Turbulence is not confined to the wakes of galaxies but is instead volume filling, due to the excitation of large-scale g-modes. We systematically probe the parameter space of galaxy masses and numbers to assess when the cooling catastrophe is prevented. For a wide range of observationally motivated galaxy parameters, we find that the magnetic field is randomized by stirring motions, restoring the conductive heat flow to the core. The cooling catastrophe either does not occur or it is sufficiently delayed to allow the cluster to experience a major merger that could reset the conditions in the intracluster medium. Whilst dissipation of turbulent motions (and hence dynamical friction heating) is negligible as a heat source, turbulent heat diffusion is extremely important; it predominates in the cluster centre. However, thermal conduction becomes important at larger radii, and simulations without thermal conduction suffer a cooling catastrophe. Conduction is important both as a heat source and to reduce stabilizing buoyancy forces, enabling more efficient diffusion. Turbulence enables conduction, and conduction enables turbulence. In these simulations, the gas vorticity – which is a good indicator of trapped g-modes – increases with time. The vorticity growth is approximately mirrored by the growth of the magnetic field, which is amplified by turbulence.
Smoothing grouped bivariate data to obtain the incubation period distribution of aids

We use a penalized likelihood approach to obtain a smooth estimate of a bivariate distribution from grouped data where each observation consists of a region in a plane. The purpose of the analysis is to estimate the incubation period distribution of AIDS from the Multicenter AIDS Cohort Study, a prevalent cohort of homosexual men. In this article we illustrate the usefulness of the penalized likelihood approach. We also discuss the use of a cross-validation and a Bayesian scheme to choose the smoothing parameters and bootstrap samples to assess uncertainty.
Efficient parallel algorithms for processing biological sequences

Processing of biological sequences is a compute-intensive problem. The amount of data available in biology is so enormous that sequential techniques take a very long time to process them. In this paper, we present some parallel algorithms for biological data processing. We consider a scenario where the operations performed on the sequences are arbitrary. In particular, we assume that a sequential algorithm can be executed in parallel by a number of processors on an input consisting of a file of sequences to be processed. The goal is to process all these sequences as efficiently as possible. We present four parallel algorithms in this paper: Algorithms 1-4. Algorithm 1 is shown to be (1+α)-competitive with high probability for any fixed α>0 under suitable assumptions. Algorithm 2 is shown to be O(1)-competitive and Algorithm 3 is shown to be 2-competitive. We have experimentally compared the performance of these four algorithms and the results are presented.
Bounding the graviton mass with binary pulsar observations

By comparing the observed orbital decay of the binary pulsars PSR B1913+16 and PSR B1534+12 to that predicted by general relativity due to gravitational-wave emission, we are able to bound the mass of the graviton to be less than 7.6 × 10(−20) eV/c(2) at 90% confidence. This is the first such bound to be derived from dynamic gravitational fields. It is approximately two orders of magnitude weaker than the static-field bound from solar system observations, and will improve with further observations.
UNDERSTANDING REVOLUTION IN THE MIDDLE EAST: THE CENTRAL ROLE OF THE MIDDLE CLASS

The paper presents the outlines of a coherent, structural, long term account of the socio-economic and political evolution of the Arab republics that can explain both the persistence of autocracy until 2011, and the its eventual collapse, in a way that is empirically verifiable. I argue that the changing interests of the middle class would have to be a central aspect of a coherent story, on accounts of both distributional and modernization considerations, and that the ongoing transformation can be best understood in terms of their defection from the autocratic order to a new democratic order, which is still in formation. I then review what the evidence says in two central parts of the emerging narrative, for the case of Egypt: first, by looking directly at changes in opinion and asking whether these are consistent with the predictions of the theory. And second, by examining the corporate sector before and during the uprisings of 2011 in order to understand better the performance of “crony capitalism”, and...
Specific fate decisions in adult hepatic progenitor cells driven by MET and EGFR signaling

The relative contribution of hepatocyte growth factor (HGF)/MET and epidermal growth factor (EGF)/EGF receptor (EGFR), two key signal transduction systems in the normal and diseased liver, to fate decisions of adult hepatic progenitor cells (HPCs) has not been resolved. Here, we developed a robust culture system that permitted expansion and genetic manipulation of cells capable of multilineage differentiation in vitro and in vivo to examine the individual roles of HGF/MET and EGF/EGFR in HPC self-renewal and binary cell fate decision. By employing loss-of-function and rescue experiments in vitro, we showed that both receptors collaborate to increase the self-renewal of HPCs through activation of the extracellular signal-regulated kinase (ERK) pathway. MET was a strong inducer of hepatocyte differentiation by activating AKT and signal transducer and activator of transcription (STAT3). Conversely, EGFR selectively induced NOTCH1 to promote cholangiocyte specification and branching morphogenesis while concomitantly suppressing hepatocyte commitment. Furthermore, unlike the deleterious effects of MET deletion, the liver-specific conditional loss of Egfr facilitated rather than suppressed progenitor-mediated liver regeneration by switching progenitor cell differentiation toward hepatocyte lineage. These data provide new insight into the mechanisms regulating the stemness properties of adult HPCs and reveal a previously unrecognized link between EGFR and NOTCH1 in directing cholangiocyte differentiation.
Energy, life, and ATP.

The mechanism by which ATP is synthesized during oxidative and photophosphorylation has been elucidated by oxygen exchange and other studies: a novel form of catalysis--termed rotary catalysis--is involved.
Synthesis of ortho‐Acylphenols through the Palladium‐Catalyzed Ketone‐Directed Hydroxylation of Arenes

Ketone in charge: a formal ketone-directed palladium-catalyzed ortho-hydroxylation of arenes has been developed as an effective approach to access o-acylphenols from simple arylketones. A Pd-catalyzed oxidative ortho-carbonylation reaction using ketone directing groups to access a ketal-lactone motif is also demonstrated. The ubiquity and versatile nature of ketones make these methods attractive. BTI=PhI(TFA)(2); DCE=1,2-dichloroethane.
A computer engineering laboratory

The advent of modern electronic computers has expanded the scope of nearly all areas of scientific endeavor. The electrical engineer is perhaps most acutely affected by this expanision by virtue of his two-fold interest in computer processes. He is, as are his colleagues of other scientific disciplines, excited by the computing capabilities now at his disposal. Even more, he is deeply involved by virtue of his responsibility for the conception and design of the computer and its hardware adaptation to a variety of applications. It is to the second phase of the electrical engineer's involvement with computers that our educational activities are directed, that is, to his involvement in the realization of computers or computerlike systems.
Exponential Growth Bias and Household Finance

Exponential growth bias is the pervasive tendency to linearize exponential functions when assessing them intuitively. We show that exponential growth bias can explain two stylized facts in household finance: the tendency to underestimate an interest rate given other loan terms, and the tendency to underestimate a future value given other investment terms. Bias matters empirically: More-biased households borrow more, save less, favor shorter maturities, and use and benefit more from financial advice, conditional on a rich set of household characteristics. There is little evidence that our measure of exponential growth bias merely proxies for broader financial sophistication. WHAT DRIVES HOUSEHOLD financial decisions? The canonical economic model assumes that consumers choose to consume, borrow, or save based on their preferences, their expectations, and the costs and benefits of borrowing and saving. A growing body of work applies insights from psychology to enrich specifications of three of the model’s key pieces: preferences, expectations, and problem-solving conditional on parameter values. 1 In this paper, we bring psychological evidence to bear on a fourth specification issue: How consumers perceive the costs and benefits of borrowing and saving. We begin by tying together existing and new evidence on these cost perceptions to show that most consumers err systematically when given information commonly available in the market. On the saving side, consumers display future value bias: a systematic tendency to underestimate a future value given
Three-dimensional halfspace constructive solid geometry tree construction from implicit boundary representations

Abstract This paper presents a new method to compute constructive solid geometry (CSG) tree representations of an object whose faces consist of planar and non-planar surfaces. The algorithm described accepts as input a valid boundary representation of an object consisting of piecewise implicit surfaces, and computes a halfspace CSG representation of the object. A class of objects that are describable by the surfaces bounding them are valid input for the algorithm of this work, although methods currently exist to compute the additional information necessary to process non-describable quadric objects as well. This work builds on and complements the other work in this area, in which dominating halfspaces are used to simplify the b-rep to CSG conversion process. We include factored faces to enable the factorization of dominating halfspaces throughout the algorithm. Thus, an efficient disjoint decomposition of the solid is obtained as a matter of course in the algorithm, so that CSG minimization is generally not necessary. This work is motivated by reverse engineering of mechanical parts, in which a model of a part is recovered from information obtained by some sort of sensing technique (e.g. CAT scanning, laser range finding). The recovery of a valid CSG-tree description of an object from a boundary representation of it can provide useful information to an engineer in the area of reverse engineering and in other areas related to solid modeling as well. The CSG tree also provides a relatively neutral representation that can enhance form feature recognition and translation.
Renormalization group analysis of turbulence

▪ Abstract The renormalization-group (RG) analysis of turbulence, based primarily on KG Wilson's coarse-graining procedure, leads to suggestive results for turbulence coefficients and models. Application of the method to turbulence evolved from the contributions of many authors and received widespread attention following the 1986 work of V Yakhot and SA Orszag. The Yakhot-Orszag method involves the basic renormalization-group scale-removal procedure, as well as additional hypotheses and approximations; their analysis is reviewed here with an attempt to clarify those approximations. Discussion of some related and subsequent literature is also included. Following the work of M Avellaneda and AJ Majda, a simpler version of the method is appplied to a model passive scalar problem wherein it is seen that, in certain cases, the RG method can recover exact results.
Yoctocalorimetry: phonon counting in nanostructures

Abstract It appears feasible with nanostructures to perform calorimetry at the level of individual thermal phonons. Here I outline an approach employing monocrystalline mesoscopic insulators, which can now be patterned from semiconductor heterostructures into complex geometries with full, three-dimensional relief. Successive application of these techniques also enables definition of integrated nanoscale thermal transducers; coupling these to a dc SQUID readout yields the requisite energy sensitivity and temporal resolution with minimal back action. The prospect of phonon counting opens intriguing experimental possibilities with analogies in quantum optics. These include fluctuation-based phonon spectroscopy, phonon shot noise in the energy relaxation of nanoscale systems, and quantum statistical phenomena such as phonon bunching and anticorrelated electron–phonon exchange.
An asymptotic analysis of hierarchical control of manufacturing systems

An asymptotic analysis of a hierarchical manufacturing system with machines subject to breakdown and repair is presented. The machine fluctuations are much faster than the accumulation and discounting of costs, and this gives rise to a limiting problem in which the stochastic machine availability is replaced by the equilibrium mean availability. The value function for the original problem converges to the value function of the limiting problem. The limiting problem is computationally tractable and sometimes has a closed-form solution. >
Handling the weather : insurance, savings, and credit in West Africa

Farmers in developing countries face a wide array of risks. Yet they often lack formal financial instruments to protect against risks. This paper examines the impact on consumption, investment, and welfare of the separate provision of three financial products: weather insurance, savings, and credit. The paper develops a dynamic stochastic mode to capture the essential features of the lives of West African rural households. The model is calibrated with data from farmers in Burkina Faso and Senegal, to assess quantitatively the effects of three policy interventions. For each intervention the analysis first considers a benchmark scenario that abstracts from the flaws that affect each instrument; later the assumptions are relaxed. Weather insurance offers the largest welfare gains at each level of wealth, although the gains are significantly reduced by introducing a multiple on the insurance premium. Over time, however, savings can lead to substantial gains, higher than those achievable by unsubsidized weather insurance.
ENDOGENOUS GROWTH MODELS AND THE ENVIRONMENTAL KUZNETS CURVE: AN ANALYSIS OF GLOBAL ENVIRONMENTAL SUSTAINABILITY

Fertilizer consumption per cubic meter of freshwater is taken as a proxy for global water quality indicator. A global model of environmental quality for 121 countries confirms the Kuznet's hypothesis. Global turning point is reached at nearly five times the average income of all countries. Foreign Direct Investment (FDI) was significant to increase the national income. Increased aid and larger farm size per capita favored higher environmental quality, albeit insignificant. A flow of better technology and possible non-agricultural employment might help improve water quality in developing countries when their net income increases.
Voting Equilibria in Multi-candidate Elections

We consider a general plurality voting game with multiple candidates, where voter preferences over candidates are exogenously given. In particular, we allow for arbitrary voter indifferences, as may arise in voting subgames of citizen-candidate or locational models of elections. We prove that the voting game admits pure strategy equilibria in undominated strategies. The proof is constructive: we exhibit an algorithm, the “best winning deviation” algorithm, that produces such an equilibrium in finite time. A byproduct of the algorithm is a simple story for how voters might learn to coordinate on such an equilibrium.
Synthesis and preliminary evaluation of trans-3,4-conformationally-restricted glutamate and pyroglutamate analogues as novel EAAT2 inhibitors.

Abstract Select trans-4,5-[bi]cyclohexenylglutamic and pyroglutamic acids (3,4-substituted glutamates) were synthesized in three steps and were screened as potential inhibitors of the sodium dependent excitatory amino acid transporters 2 (EAAT2) and 3 (EAAT3), the chloride dependent glial cystine/glutamate exchanger system xc−, and the glutamate vesicular transport system (VGLUT). Two glutamate analogues and one pyroglutamate analogue were found to inhibit EAAT2 with activity comparable to dihydrokainate.
Riemannian manifolds with local symmetry

We give a classification of many closed Riemannian manifolds M whose universal cover $\widetilde{M}$ possesses a nontrivial amount of symmetry. More precisely, we consider closed Riemannian manifolds M such that ${\rm Isom}(\widetilde{M})$ has noncompact connected components. We prove that in many cases, such a manifold is as a fiber bundle over a locally homogeneous space. This is inspired by work of Eberlein (for non-positively curved manifolds) and Farb-Weinberger (for aspherical manifolds), and generalizes work of Frankel (for a semisimple group action). As an application, we characterize simply-connected Riemannian manifolds with both compact and finite volume noncompact quotients.
A Transfer-Function-Based Thermal Model Reduction Study for Induction Machine Thermal Overload Protective Relays

High-order induction machine thermal models have been widely studied for the analysis of the thermal behavior of induction machines. However, the real-time implementation of such models for the online thermal protection of induction machines is very difficult due to the lack of accurate information on the machines. This paper proposes a novel simplified thermal model of induction machines for thermal overload relays. Instead of using a lumped thermal network, a transfer-function-based approach is proposed for reducing the order of induction machine thermal models. The proposed thermal model requires significantly fewer thermal parameters for the accurate modeling of the thermal behavior of the machine. The proposed thermal model is validated via experimental results on a 7.5-hp open-drip-proof induction machine under various load conditions. The major features of the proposed thermal model are the following: 1) high accuracy of the stator winding temperature estimation, with a root-mean-square error within 3°C; 2) low computational requirement, which reduces the cost of thermal overload relays; and 3) easy implementation since only current sensors are required.
Catalytic enantioselective nucleophilic addition of ynamides to aldehydes

The first catalytic asymmetric addition of ynamides to aliphatic and aromatic aldehydes is described. This reaction provides unprecedented access to a diverse family of N-substituted propargylic alcohols that are obtained in high yield and ee in the presence of 10 mol% of zinc triflate and N-methylephedrine. The use of apolar solvent mixtures is essential to avoid product racemization and to optimize ee's without compromising conversion.
Addition of trialkylaluminum reagents to glyconolactones. Synthesis of 1-C-methyl GlcNAc oxazoline and thiazoline

Abstract Addition of carbon nucleophiles to 2-acetamido-2-deoxygluconolactones fails for many reagents, but trialkylaluminums add alkyl smoothly. The product of methyl addition to 2-acetamido-2-deoxy- d -gluconolactone has been converted to 1- C -methyl GlcNAc thiazoline, a potential N -acetylhexosaminidase inhibitor, and to an O -protected 1- C -Me GlcNAc oxazoline, a potential 1- C -Me GlcNAc donor.
Testing the gaugino AMSB model at the Tevatron via slepton pair production

Gaugino AMSB models — wherein scalar and trilinear soft SUSY breaking terms are suppressed at the GUT scale while gaugino masses adopt the AMSB form — yield a characteristic SUSY particle mass spectrum with light sleptons along with a nearly degenerate wino-like lightest neutralino and quasi-stable chargino. The left-sleptons and sneutrinos can be pair produced at sufficiently high rates to yield observable signals at the Fermilab Tevatron. We calculate the rate for isolated single and dilepton plus missing energy signals, along with the presence of one or two highly ionizing chargino tracks (HITs). We find that Tevatron experiments should be able to probe gravitino masses into the ∼55 TeV range for inoAMSB models (depending on detector-dependent HIT detection efficiency), which corresponds to a reach in gluino mass of over 1100 GeV.
Free electron lasers with slowly varying beam and undulator parameters

A self-consistent theory of a free electron laser (FEL) with slowly varying beam and undulator parameters is developed using the WKB approximation. The theory is applied to study the performance of a self-amplified spontaneous emission (SASE) FEL when the electron beam energy varies along the undulator as would be caused by vacuum pipe wakefields and/or when the undulator strength parameter is tapered in the small signal regime before FEL saturation. We find that a small energy gain or an equivalent undulator taper slightly reduces the power gain length in the exponential growth regime and can increase the saturated SASE power by about a factor of 2. Power degradation away from the optimal performance can be estimated based upon knowledge of the SASE bandwidth. The analytical results, which agree with numerical simulations, are used to optimize the undulator taper and to evaluate wakefield effects.
A monolithic digital chirp synthesizer chip with I and Q channels

A monolithic digital chirp synthesizer (DCS) chip has been developed using GaAs/AlGaAs HI/sup 2/L technology. The 6500-HBT-gate DCS chip is capable of producing linear frequency-modulated (chirp) waveforms or single-frequency waveforms. The major components of the DCS are two 28-b pipelined accumulators, a 1.8 kb sine ROM, a 1.8 kb cosine ROM, and two 8 b digital-to-analog converters (DACs). The total chip area is 4.877 mm*6.172 mm using a minimum feature size of 1.5 mu m. All components of the DCS are fully functional and the device has been clocked to 450 MHz with a power dissipation of 18 W. >
Sensitivity analysis based approximation models for day-to-day link flow evolution process

Abstract Compared with path-based day-to-day (DTD) traffic evolution models, link-based DTD traffic evolution models are easier to calibrate and validate. However, the inherent network loading sub-problem in link-based DTD models induces high computational burden which precludes their broad practical applicability. To address this challenge, this study proposes three approximation models for the DTD traffic flow evolution process based on the sensitivity analysis of the network loading sub-problem in a link-based DTD model. In particular, a first-order approximation (FOA) model is formulated based on the derivative of link flow solutions with respect to perturbations on network characteristics. To improve the approximation accuracy of the FOA model, a second-order approximation (SOA) model and a variable reduced approximation (VRA) model are developed. The applicability conditions of the proposed approximation models are derived. A small numerical example demonstrates that the FOA model performs well when perturbations are small and the approximation accuracy reduces as the scale of perturbations increases. The SOA and VRA models can improve the approximation accuracy of the FOA model, at the cost of computing the second-order derivative and the reference link flow pattern, respectively.
Singular values and vectors of a class of Hankel operators

Abstract This paper considers the problem of determining the singular values and vectors of the class of Hankel operators whose symbol can be written in the form φ ∗ W where φ is inner and W is rational. We will obtain a new and simplified proof of the fact, conjectured in [17] and first proved in [9], that the zeros of a certain determinantal expression coincide with the Hankel singular values. We will also show how this expression can be used to generate the singular vectors.
Intermolecular C–H Insertions of Carbenoids

The metal-catalyzed reactions of diazo compounds have broad utility in organic synthesis. The resulting high-energy metal carbenoid intermediates are capable of a range of useful transformations, including cyclopropanation, ylide formation, and C-H insertion. The intermolecular C-H insertion by metal carbenoids is the most versatile reaction to date for stereoselective C-H functionalization. This chapter covers the historical background of C-H insertions and describes how the utilization of new catalysts and more stabilized carbenoids has resulted in major advances in the field. Now that highly diastereoselective and enantioselective C-H functionalization can be achieved, the method can be effectively applied to the synthesis of pharmaceutical agents and natural products. This chapter focuses exclusively on intermolecular C-H insertions of metal carbenoids in sp3-hybridized C-H bonds. The carbenoids can be classified into three major classes: 1, acceptor-substituted carbenoids; 2, acceptor/acceptor-substituted carbenoids; and 3, donor/acceptor-substituted carbenoids Keywords: Intermolecular C-H insertions; Carbenoids; Hydrocarbons; Activated C-H bonds; Site selectivity; Donors; Acceptors; Aryldiazoacetates; Metal catalysts; Experimental procedures; Mechanisms
Probabilistic noninterference in a concurrent language

In previous work (Smith and Volpano, Proceedings 25th Symposium on Principles of Programming Languages, San Diego, CA, 1998, pp. 355-364), we give a type system that guarantees that well-typed multi-threaded programs are possibilistically noninterfering. If thread scheduling is probabilistic, however, then well-typed programs may have probabilistic timing channels. We describe how they can be eliminated without making the type system more restrictive. We show that well-typed concurrent programs are probabilistically noninterfering if every total command with a guard containing high variables executes atomically. The proof uses the notion of a probabilistic state of a computation from Kozens work in the denotational semantics of probabilistic programs (Kozen, Journal of Computer and System Sciences 22 (1981), 328-350).^{2}
Free Radical Chain Processes in Aliphatic Systems involving an Electron Transfer Reaction

Publisher Summary This chapter reviews that the occurrence of electron transfer reactions greatly expands the scope of free radical chain processes and provides a crossing of the boundary between polar and homolytic processes. The formation of a radical ion from a neutral substrate or a radical from an ion can be considered to be a type of activation. Electron transfer between radical ions and easily oxidized or reduced substrates is a common process. It explores that the mechanistic possibilities for free radical chain processes are greatly expanded by the recognition that there is a bridge between radical ion chemistry and the chemistry of separated radicals and ions because in appropriate cases radical ions can dissociate to form a radical and an ion, or conversely, radicals may add to ions to form radical ions. The occurrence of free radical chain processes involving electron transfer is likely to occur when easily oxidized or reduced substrates are involved with radical anion formation being favored by strongly basic or reductive conditions and radical cations by acidic or oxidative environments.
Landau singularities and symbology: one- and two-loop MHV amplitudes in SYM theory

We apply the Landau equations, whose solutions parameterize the locus of possible branch points, to the one- and two-loop Feynman integrals relevant to MHV amplitudes in planar $$ \mathcal{N}=4 $$ super-Yang-Mills theory. We then identify which of the Landau singularities appear in the symbols of the amplitudes, and which do not. We observe that all of the symbol entries in the two-loop MHV amplitudes are already present as Landau singularities of one-loop pentagon integrals.
Drainage Wells in Leaky Water-Table Aquifers

Flow formulas are found for well draining water-table aquifer that overlies semipervious layer; leaky water-table aquifer is replenished by vertical percolation due to excess irrigation or leaching or both; function depending on 2 parameters is tabulated in order to simplify calculations leading to determination of appropriate well discharge and spacing; expression for time required to lower water table.