cssi/SciSciGPT-SciSciNet huggingface dataset:
Improved Source Coding Exponents via Witsenhausen's Rate

We provide a novel upper-bound on Witsenhausen's rate, the rate required in the zero-error analogue of the Slepian-Wolf problem. Our bound is given in terms of a new information-theoretic functional defined on a certain graph and is derived by upper bounding complementary graph entropy. We use the functional, along with graph entropy, to give a single letter lower-bound on the error exponent for the Slepian-Wolf problem under the vanishing error probability criterion, where the decoder has full (i.e., unencoded) side information. We demonstrate that our error exponent can beat the “expurgated” source-coding exponent of Csiszar and Korner for some sources that have zeroes in the “channel” matrix connecting the source with the side information. An extension of our scheme to the lossy case (i.e., Wyner-Ziv) is given. For the case in which the side information is a deterministic function of the source, the exponent of our improved scheme agrees with the sphere-packing bound exactly (thus determining the reliability function). An application of our functional to zero-error channel capacity is also given.
A 500-MSample/s, 6-bit Nyquist-rate ADC for disk-drive read-channel applications

The analog-to-digital conversion required in most disk-drive read-channel applications is designed for good dynamic and noise performance over a wide-input frequency range. This paper presents a 500-MSample/s, 6-bit analog to-digital converter (ADC) and its embedded implementation inside a disk-drive read channel, using a 0.35-/spl mu/m CMOS double-poly (only one poly layer was used in the ADC), triple-metal process. The converter achieves better than 5 effective number of bits (ENOB) for input frequencies up to Nyquist frequency (f/sub in/=f/sub s//2) and sampling frequencies f/sub s/ up to 400 MHz. It also achieves better that 5.6 ENOB for input frequencies up to f/sub s//4 over process, temperature, and power-supply variations. At maximum speed (f/sub s/=500 MHz), the converter still achieves better than 5 ENOB for input frequencies up to f/sub in/=200 MHz. Low-frequency performance is characterized by DNL<0.32 LSB and INL<0.2 LSB. The converter consumes 225 mW from a 3.3-V supply when running at 300 MHz and occupies 0.8 mm/sup 2/ of chip area.
Design, synthesis and biological activity of β-carboline-based type-5 phosphodiesterase inhibitors

The SAR of a series of beta-carboline derived type 5 phosphodiesterase inhibitors has been explored and we have discovered compounds with excellent levels of PDE5 potency and selectivity over PDE6. However, the series exhibits low levels of selectivity over PDE11, a phosphodiesterase with unknown function.
Why the characteristic polynomial factors

We survey three methods for proving that the characteristic polynomial of a finite ranked lattice factors over the nonnegative integers and indicate how they have evolved recently. The first technique uses geometric ideas and is is based on Zaslavsky’s theory of signed graphs. The second approach is algebraic and employs results of Saito and Terao about free hyperplane arrangements. Finally we consider a purely combinatorial theorem of Stanley about supersolvable lattices and its generalizations.
Recessed electrodes formed by laser ablation of parylene coated, micromachined silicon probes

A drawback of planar stimulating electrodes is the large current densities produced at the edge of the electrode. Such non-uniformity can be reduced by recessing the electrode. Research is presented that discusses the formation of recessed electrodes by laser ablation of parylene coating on silicon micromachined probes with thin-film iridium electrodes. Parylene was deposited conformal to the probe. A UV laser was used to remove the parylene over a 1750 /spl mu/m/sup 2/ planar, rectangular electrode, forming a recess about the electrode. A residual parylene layer (resulting in an increased impedance), that could not be ablated without harming the thin-film metal, was removed both by inducing gas evolution at the metal-electrolyte interface and by using an oxygen plasma to etch the parylene. Removal of this layer restored the electrode impedance to near nominal values. Iridium oxide was electrochemically formed on the electrodes. Recessed electrodes attained a charge storage capacity equal to that of non-recessed electrodes. Impedance spectroscopy revealed that the access resistance increased with recess depth, from 5.2 kOhm (non-recessed) to 6.4 kOhm (8 /spl mu/m recess). Finite element modeling predicts that both the depth and shape of the recess will affect the electrical properties of the electrode.
Towards a combinatorial representation theory for the rational Cherednik algebra of type G ( r, p, n )

The goal of this paper is to lay the foundations for a combinatorial study, via orthogonal functions and intertwining operators, of category O for the rational Cherednik algebra of type G(r,p,n). As a first application, we give a self-contained and elementary proof of the analog for the groups G(r,p,n), with r>1, of Gordon's theorem (previously Haiman's conjecture) on the diagonal coinvariant ring. We impose no restriction on p; the result for p<r has been proved by Vale using a technique analogous to Gordon's. Because of the combinatorial application to Haiman's conjecture, the paper is logically self-contained except for standard facts about complex reflection groups. The main results should be accessible to mathematicians working in algebraic combinatorics who are unfamiliar with the impressive range of ideas used in Gordon's proof of his theorem.
Functional equivalence of the nicotinic acetylcholine receptor transmitter binding sites in the open state.

The subunits of the muscle-type nicotinic acetylcholine receptor (AChR) are not uniformly oriented in the resting closed conformation: the two α subunits are rotated relative to its non-α subunits. In contrast, all the subunits overlay well with one another when agonist is bound to the AChR, suggesting that they are uniformly oriented in the open receptor. This gating-dependent increase in orientational uniformity due to rotation of the α subunits might affect the relative affinities of the two transmitter binding sites, making the two affinities dissimilar (functionally non-equivalent) in the initial ligand-bound closed state but similar (functionally equivalent) in the open state. To test this hypothesis, we measured single-channel activity of the αG153S gain-of-function mutant receptor evoked by choline, and estimated the resting closed-state and open-state affinities of the two transmitter binding sites. Both model-independent analyses and maximum-likelihood estimation of microscopic rate constants indicate that channel opening makes the binding sites' affinities more similar to each other. These results support the hypothesis that open-state affinities to the transmitter binding sites are primarily determined by the α subunits.
Effects of Kinematic Constraints on Teleseismic Finite-Source Rupture Inversions: Great Peruvian Earthquakes of 23 June 2001 and 15 August 2007

Two great underthrusting earthquakes that occurred along the coast of Peru in 2001 and 2007 involve spatiotemporal slip distributions that differ from the predominantly unilateral or bilateral rupture expansion of many great events. Commonly used finite-source rupture model parameterizations, with specified rupture velocity and/or short duration of slip at each grid point applied to the seismic data for these two events, lead to incorrect slip-distributions or inaccurate estimation of rupture velocities as a result of intrinsic kinematic constraints imposed on the model slip distributions. Guided by large aperture array back projections of teleseismic broadband P-wave signals that image slip locations without imposing a priori kinematic constraints on the rupture process, we exploit the availability of large global broadband body and surface wave data sets to consider the effects of varying the kinematic constraints in teleseismic finite-source waveform inversions. By allowing longer than usual rupture durations at each point on the fault using a flexible subfault source-time function parameterization, we find that the anomalous attributes of the 2001 and 2007 Peru earthquake ruptures are readily recognized and accounted for by compound rupture models. The great 23 June 2001 (M_w 8.4 8.4) earthquake involved an initial modest-size event that appears to have triggered a much larger secondary event about 120 km away that developed an overall slip distribution with significant slip located back along the megathrust in the vicinity of the initial rupture. The great 15 August 2007 (M_w 8.0 8.0) earthquake was also a composite event, with a modest size initial rupture followed by a 60-sec delayed larger rupture that initiated 50–60 km away and spread up-dip and bilaterally. When back projections indicate greater rupture complexity than captured in a simple slip-pulse-type rupture model, one should allow for possible long-subfault slip-duration or composite triggered sequences, and not overly constrain the earthquake slip distribution.
Ruthenium-catalyzed tandem enyne metathesis/hydrovinylation

In situ modification of Grubbs' first-generation metathesis catalyst allows for a tandem enyne metathesis/hydrovinylation that is complementary to the regioselectivity of known ruthenium-catalyzed hydrovinylations.
Complexity, cofactors, and the failure of AIDS policy in Africa

Global AIDS policy still treats HIV as an exceptional case, abstracting from the context in which infection occurs. Policy is based on a simplistic theory of HIV causation, and evaluated using outdated tools of health economics. Recent calls for a health systems strategy – preventing and treating HIV within a programme of comprehensive health care – have not yet influenced the silo approach of AIDS policy.
Lifting M theory to two time physics

Abstract M-theory has different global supersymmetry structures in its various dual incarnations, as characterized by the M-algebra in 11D, the type IIA, type-IIB, heterotic, type-I extended supersymmetries in 10D, and non-Abelian supersymmetries in the AdSn×Sm backgrounds. We show that all of these supersymmetries are unified within the supersymmetry OSp 1/64 , thus hinting that the overall global spacetime symmetry of M-theory is OSp 1/64 . We suggest that the larger symmetries contained within OSp 1/64 which go beyond the familiar symmetries, are non-linearly realized hidden symmetries of M-theory. These can be made manifest by lifting 11D M-theory to the formalism of two-time physics in 13D by adding gauge degrees of freedom. We illustrate this idea by constructing a toy M-model on the worldline in 13D with manifest OSp 1/64 global supersymmetry, and a number of new local symmetries that remove ghosts. Some of the local symmetries are bosonic cousins of kappa supersymmetries. The model contains 0-superbrane and p-forms (for p= 3, 6) as degrees of freedom. The gauge symmetries can be fixed in various ways to come down to a one time physics model in 11D, 10D, AdSn×Sm, etc., such that the linearly realized part of OSp 1/64 is the global symmetry of the various dual sectors of M-theory.
Maximizing the system value while satisfying time and energy constraints

Embedded devices designed for various real-time applications typically have three constraints that must be addressed: energy, deadlines, and reward. These constraints play important roles in the next generation of embedded systems, since they provide users with a variety of quality-of-service (QoS) tradeoffs. We propose a QoS model in which applications may have several versions, each with different time and energy requirements, while providing different levels of accuracy (reward). An optimal scheme would allow the device to run the most critical and valuable versions of applications without depleting the energy source, while still meeting all deadlines. A solution is presented for frame-based and periodic task sets. Three algorithms are devised that closely approximate the optimal solution while taking only a fraction of the runtime of an optimal solution.
The Effects of Dynamic Changes in Bank Competition on the Supply of Small Business Credit

We study the effects of structural changes in banking markets on the supply of credit to small businesses. Specifically, we examine whether bank mergers and acquisitions (M&As) and entry have "external" effects on small business loans by other banks in the same local markets. The results suggest modest positive external effects from these dynamic changes in competition, except that large banks may reduce small business lending in reaction to entry. We confirm bank size and age as important determinants of this lending, and show that the measured age effect does not appear to be driven by local market M&A activity.
Modification of the Niacin Furfuryl Reaction by Diphosphopyridin Nucleotide in Rheumatoid Arthritis

Summary NF ointment produces erythema in normal and non-active rheumatoid arthritis cases, while with rheumatoid activity there develops an absence of such reaction.NF erythema is modified by prior application of DPN ointment.In cases where NF produces erythema, DPN reduces the intensity of such reaction.In very active rheumatoid cases, where NF ointment does not produce erythema, the prior application of DPN ointment produces a faint redness.The modification of the NF test by DPN ointment corroborates the view that the function and status of DPN is intimately involved in the pathogenesis of rheumatoid arthritis.
Discovering personal gazetteers: an interactive clustering approach

Personal gazetteers record individuals' most important places, such as home, work, grocery store, etc. Using personal gazetteers in location-aware applications offers additional functionality and improves the user experience. However, systems then need some way to acquire them.This paper explores the use of novel semi-automatic techniques to discover gazetteers from users' travel patterns (time-stamped location data). There has been previous work on this problem, e.g., using ad hoc algorithms [13]or K-Means clustering[4]; however, both approaches have shortcomings. This paper explores a deterministic, density-based clustering algorithm that also uses temporal techniques to reduce the number of uninteresting places that are discovered. We introduce a general framework for evaluating personal gazetteer discovery algorithms and use it to demonstrate the advantages of our algorithm over previous approaches.
Scale-space based feature point detection for digital ink

Feature point detection is generally the first step in model-based approaches to sketch recognition. Feature point detection in free-hand strokes is a hard problem because the input has noise from digitization, from natural hand tremor, and from lack of perfect motor control during drawing. Existing feature point detection methods for free-hand strokes require hand-tuned thresholds for filtering out the false positives. In this paper, we present a threshold-free feature point detection method using ideas from the scale-space theory.
Buffer Insertion for Bridges and Optimal Buffer Sizing for Communication Sub-System of Systems-on-Chip

We have presented an optimal buffer sizing and buffer insertion methodology which uses stochastic models of the architecture and Continuous Time Markov Decision Processes CTMDPs. Such amethodology is useful in managing the scarce buffer resources available on chip as compared to network based data communication which can have large buffer space. The modeling of this problem in terms of a CT-MDP framework lead to a nonlinear formulation due to usage of bridges in the bus architecture. We present a methodology to split the problem into several smaller though linear systems and we then solve these subsystems.
Algebraic Multigrid for Linear Systems Obtained by Explicit Element Reduction

We consider sparse linear systems, where a set of “interior” degrees of freedom have been eliminated in order to reduce the problem size. This elimination is assumed to be local, so the “interior” principal submatrix is block-diagonal, and the resulting Schur complement is still sparse. For it to be beneficial, the elimination process should lead to reduced memory requirements, but equally importantly, it should also result in an algebraic problem that can be solved efficiently. In this paper we propose a general element reduction approach and show how the elimination process can exploit a particular “subzonal” discretization to maintain the sparsity of the Schur complement. We also investigate algebraic multigrid (AMG) solution algorithms applied to the reduced problem, and we discuss the influence of the local elimination on solver-related properties of the matrix, such as near-nullspace preservation and the availability of stable subspace decompositions. We focus on BoomerAMG, a parallel variant of classical Ruge-Stuben AMG, applied to scalar diffusion problems [V. Henson and U. Yang, Appl. Numer. Math., 41 (2002), pp. 155-177], and the auxiliary-space Maxwell solver (AMS) for electromagnetic diffusion applications [T. Kolev and P. Vassilevski, J. Comput. Math., 27 (2009), pp. 604-623]. In the electromagnetic case, we establish algebraically a reduced version of the Hiptmair-Xu decomposition from [R. Hiptmair and J. Xu, SIAM J. Numer. Anal., 45 (2007), pp. 2483-2509] and consider a modification of the reduction process that targets the singular problems arising in simulations with pure void (zero conductivity) regions. For scalar diffusion problems, our particular stencil analysis shows that the reduction has a positive effect on meshes with stretched elements. We present a number of two-dimensional, three-dimensional, and axisymmetric numerical experiments, which demonstrate that the combination of an appropriately chosen local elimination with the use of the BoomerAMG and AMS solvers can lead to significant improvements in the overall solution time.
Power-Aware Wireless File Downloading: A Lyapunov Indexing Approach to a Constrained Restless Bandit Problem

This paper treats power-aware throughput maximization in a multiuser file downloading system. Each user can receive a new file only after its previous file is finished. The file state processes for each user act as coupled Markov chains that form a generalized restless bandit system. First, an optimal algorithm is derived for the case of one user. The algorithm maximizes throughput subject to an average power constraint. Next, the one-user algorithm is extended to a low-complexity heuristic for the multiuser problem. The heuristic uses a simple online index policy. In a special case with no power-constraint, the multiuser heuristic is shown to be throughput-optimal. Simulations are used to demonstrate effectiveness of the heuristic in the general case. For simple cases where the optimal solution can be computed offline, the heuristic is shown to be near-optimal for a wide range of parameters.
Fischer–Tropsch Chemistry at Room Temperature?†

The unique catalytic activity of vanadium nitrogenase suggests a new direction for the direct production of biofuels from CO with either synthetic catalysts or nitrogenase-containing bacteria. The reduction of CO by V nitrogenase to light hydrocarbons shows striking similarities to the established Fischer-Tropsch process; however, the enzyme does not use H(2) directly for this reaction. ADP=adenosine diphosphate, ATP= adenosine triphosphate.
Network Structure and Observational Learning: Evidence from a Location-Based Social Network

In recent years, there has been stellar growth of location-based/enabled social networks in which people can "check in" to physical venues they are visiting and share with friends. In this paper, we hypothesize that the "check-ins" made by friends help users learn the potential payoff of visiting a venue. We argue that this learning-in-a-network process differs from the classic observational learning model in a subtle yet important way: Rather than from anonymous others, the agents learn from their network friends, about whose tastes in experience goods the agents are better informed. The empirical analyses are conducted on a unique data set in which we observe both the explicit interpersonal relationships and their ensuing check-ins. The key result is that the proportion of checked-in friends is not positively associated with the likelihood of a new visit, rejecting the prediction of the conventional observational learning model. Drawing on the literature in sociology and computer science, we show that w...
MEASUREMENT AND PREDICTION OF ROUGH WALL EFFECTS ON FRICTION FACTOR - UNIFORM ROUGHNESS RESULTS

The results of an experimental investigation of the effects of surface roughness on turbulent pipe flow friction factors are presented and compared with predictions from a previously published discrete element roughness model. Friction factor data were acquired over a pipe Reynolds number range from 10,000 to 600,000 for nine different uniformly rough surfaces. These surfaces covered a range of roughness element sizes, spacings and shapes. Predictions from the discrete element roughness model were in very good agreement with the data.
Hypertension in hemodialysis patients treated with atenolol or lisinopril: a randomized controlled trial

Background The purpose of this study was to determine among maintenance hemodialysis patients with echocardiographic left ventricular hypertrophy and hypertension whether in comparison with a β-blocker-based antihypertensive therapy, an angiotensin converting enzyme-inhibitor-based antihypertensive therapy causes a greater regression of left ventricular hypertrophy.
Willingness to Pay for Environmental Quality: Testable Empirical Implications of the Growth and Environment Literature

Several different theoretical models of economic growth and environmental quality each generate inverse-U-shaped pollution-income paths, or "environmental Kuznets curves." They rely on different assumptions to generate the reversal of pollution trends, with correspondingly different policy implications. While the empirical implications for pollution are indistinguishable (by design), the models have distinct implications for the pattern of people's marginal willingness to pay (MWTP) for environmental improvements as a function of income. In this paper we demonstrate those different implications theoretically, and test for them empirically using data from the World Value Survey (WVS). We find strong relationships between MWTP and individual characteristics, such as age, income, and education, but little evidence that MWTP varies systematically with economic growth.
Lattice polytopes cut out by root systems and the Koszul property

We show that lattice polytopes cut out by root systems of classical type are normal and Koszul, generalizing a well-known result of Bruns, Gubeladze, and Trung in type A. We prove similar results for Cayley sums of collections of polytopes whose Minkowski sums are cut out by root systems. The proofs are based on a combinatorial characterization of diagonally split toric varieties.
Moduli Potentials in Type IIA Compactifications with RR and NS Flux

We describe a simple class of type IIA string compactifications on Calabi-Yau manifolds where background fluxes generate a potential for the complex structure moduli, the dilaton, and the Kaehler moduli. This class of models corresponds to gauged {Nu} = 2 supergravities, and the potential is completely determined by a choice of gauging and by data of the {Nu} = 2 Calabi-Yau model--the prepotential for vector multiplets and the quaternionic metric on the hypermultiplet moduli space. Using mirror symmetry, one can determine many (though not all) of the quantum corrections which are relevant in these models.
Star Formation in the Field and Clusters of NGC 5253

We investigate the star formation history of both the bright star clusters and the diffuse field star population in the dwarf starburst galaxy NGC 5253 using long-slit ultraviolet spectroscopy obtained with the Space Telescope Imaging Spectrograph. The slit covers a physical area of 370 pc × 1.6 pc and includes eight apparent clusters and several intercluster regions of diffuse light that we take to be the field. The diffuse light spectrum lacks the strong O-star wind features that are clearly visible in spectra of the brightest clusters. This discrepancy provides compelling evidence that the diffuse light is not reflected light from nearby clusters but originates in a UV-bright field star population, and it raises the issue of whether the star formation process may be operating differently in the field than in the clusters. We compare our spectra to STARBURST99 evolutionary synthesis models that incorporate a new low-metallicity (~ Z☉) atlas of O-star spectra. The clusters are well fitted by instantaneous burst models with a Salpeter initial mass function (IMF) extending up to 100 M☉, and we derive ages for them ranging from 1 to 8 Myr. Reasonable fits to the field spectrum are obtained by continuous star formation models with either an upper mass cutoff of ~30 M☉ or an IMF slope steeper than Salpeter (α ~ 3.5). We favor a scenario that accounts for the paucity of O stars in the field without requiring the field to have a different IMF than the clusters: stellar clusters form continuously and then dissolve on ~10 Myr timescales and disperse their remaining stars into the field. We consider the probable contribution of an O-star-deficient field population to the spatially unresolved spectra of high-redshift galaxies.
Coordination of groups of mobile autonomous agents using nearest neighbor rules

In a recent Physical Review Letters article, Vicsek et al. propose a simple but compelling discrete-time model of n autonomous agents (i.e., points or particles) all moving in the plane with the same speed but with different headings. Each agent's heading is updated using a local rule based on the average of its own heading plus the headings of its "neighbors." In their paper, Vicsek et al. provide simulation results which demonstrate that the nearest neighbor rule they are studying can cause all agents to eventually move in the same direction despite the absence of centralized coordination and despite the fact that each agent's set of nearest neighbors change with time as the system evolves. This paper provides a theoretical explanation for this observed behavior. In addition, convergence results are derived for several other similarly inspired models. The Vicsek model proves to be a graphic example of a switched linear system which is stable, but for which there does not exist a common quadratic Lyapunov function.
Distributions in motion: economic growth, inequality, and poverty dynamics

The joint determination of aggregate economic growth and distributional change has been studied empirically from at least three different perspectives. A macroeconomic approach that relies on cross-country data on poverty, inequality, and growth rates has generated some interesting stylized facts about the correlations between these variables, but has not shed much light on the underlying determinants. “Meso-” and microeconomic approaches have fared somewhat better. The microeconomic approach, in particular, builds on the observation that growth, changes in poverty, and changes in inequality are simply different aggregations of information on the incidence of economic growth along the income distribution. This paper reviews the evolution of attempts to understand the nature of growth incidence curves, from the statistical decompositions associated with generalizations of the Oaxaca-Blinder method, to more recent efforts to generate “economically consistent” counterfactuals, drawing on structural, reduced-form, and computable general equilibrium models.
Performance analysis of a large-scale cosmology application on three cluster systems

A typical cosmological simulation requires a large amount of computing power, which is hard to satisfy with a single machine. Cluster systems provide the opportunity to execute such large-scale applications. In this paper, we investigate and analyse the performance of a large-scale production cosmology application, the ENZO code, on different cluster environments. Three cluster systems, each of them representing a widely used cluster environment in the area of scientific computing, are used in this work: an IBM SP2 system at SDSC, an IA-64 Linux cluster at NCSA and a SUN cluster at IIT. The performance is evaluated from three aspects: overall performance, communication characteristics and load balancing characteristics. The experimental data show that the cosmology performance on these clusters depends on the system performance and the application characteristics. The application performance on these clusters does not totally match the NPB measurement. Further, it seems that the IA-64 Linux cluster does not scale past 32 CPUs for this application.
QCD PHYSICS OPPORTUNITIES IN LOW-ENERGY ELECTRON-POSITRON ANNIHILATION ⁄

I survey a number of interesting tests of quantum chromodynamics at the amplitude level which can be carried out in electron-positron annihilation and in photon-photon collisions at low energy. Some of the tests require e{sup +}e{sup -} center of mass energy as small as {radical}s = 2 GeV. Other tests which involve a spectrum of energies can be carried out advantageously at high energy facilities using the radiative return method. These include measurements of fundamental processes such as timelike form factors and transition amplitudes, timelike Compton scattering, timelike photon to meson transition amplitudes, and two-photon exclusive processes. Many of these reactions test basic principles of QCD such as hadronization at the amplitude level, factorization, and hadron helicity conservation, tools also used in the analysis of exclusive B and D decays. Measurements of the final-state polarization in hadron pair production determine the relative phase of the timelike form factors and thus strongly discriminate between analytic forms of models which fit the form factors in the spacelike region. The role of two-photon exchange amplitudes can be tested using the charge asymmetry of the e{sup +}e{sup -} {yields} B{bar B} processes. These tests can help resolve the discrepancy between the Jefferson laboratory measurementsmore » of the ratio of G{sub E} and G{sub M} proton form factors using the polarization transfer method versus measurements using the traditional Rosenbluth method. Precision measurements of the electron-positron annihilation cross section can test the generalized Crewther relation and determine whether the effective couplings defined from physical measurements show infrared fixed-point and near conformal behavior. I also discuss a number of tests of novel QCD phenomena accessible in e{sup +}e{sup -} annihilation, including near-threshold reactions, the production of baryonium, gluonium states, and pentaquarks.« less
EDUCATIONAL VOUCHERS WHEN THERE ARE PEER GROUP EFFECTS—SIZE MATTERS*

In this article, I study the effects various educational voucher policies have on the sorting of children across schools and the per-student expenditure levels at these schools, when a child’s peer group matters and students differ over income and ability. I find that, depending on the magnitude of the voucher, switching from a public system to a voucher system could entail either welfare gains or losses. All voucher policies under consideration lead to greater inequality than the public system; however, these increases are not monotone in the voucher size. Several states are considering enacting or have enacted educational voucher plans, which entail giving parents money to send their children to private schools. Both the cities of Milwaukee and Cleveland have started educational voucher programs. During the 1996‐1997 school year, around 1650 students in Milwaukee received vouchers worth $4400, at a total cost of over $7 million. In the same year, Cleveland spent $6.4 million, distributing an average voucher of around $2000, to 1996 students. Other smaller scale voucher plans have sprouted up in school districts around the country. Proponents claim vouchers give poor parents educational choice for their children and give poor children a chance to succeed where the public schools fail them. Opponents argue that by funding vouchers, resources will be funneled out of the public schools to a small number of students and that the majority of students who are left behind in the public schools will suffer. In order to evaluate these proposals, a framework is needed that incorporates the factors important to educational outcomes. Along with family background and educational expenditure, many empirical studies have shown that the peer group plays a significant role in educational achievement. Consider a change in educational policy, for example, adopting a voucher system. Such a switch will affect not only
Bayesian algorithms for recovering structure from single‐particle diffraction snapshots of unknown orientation: a comparison

The advent of X-ray free-electron lasers promises the possibility to determine the structure of individual particles such as microcrystallites, viruses and biomolecules from single-shot diffraction snapshots obtained before the particle is destroyed by the intense femtosecond pulse. This program requires the ability to determine the orientation of the particle giving rise to each snapshot at signal levels as low as ~10−2 photons per pixel. Two apparently different approaches have recently demonstrated this capability. Here we show they represent different implementations of the same fundamental approach, and identify the primary factors limiting their performance.
Redox‐Neutral α,β‐Difunctionalization of Cyclic Amines

In contrast to the continuously growing number of methods that allow for the efficient α-functionalization of amines, few strategies exist that enable the direct functionalization of amines in the β-position. A general redox-neutral strategy is outlined for amine β-functionalization and α,β-difunctionalization that utilizes enamines generated in situ. This concept is demonstrated in the context of preparing polycyclic N,O-acetals from simple 1-(aminomethyl)-β-naphthols and 2-(aminomethyl)-phenols.
Sequential Activation and Deactivation of Protein Function Using Spectrally Differentiated Caged Phosphoamino Acids

Photolabile caging groups, including the 1-(2-nitrophenyl)ethyl (NPE) group, have been applied to probe many biological processes, including protein phosphorylation. Although studies with NPE-caged phosphoamino acids have provided valuable information, these investigations have been limited to the use of only one caged species in a single experiment. To expand the scope of these tools, we have developed an approach for sequentially uncaging two different phosphopeptides in one system, enabling interrogation of multiple phosphorylation events. We present the synthesis of [7-(diethylamino)coumarin-4-yl]methyl (DEACM)-caged phosphorylated serine, threonine, and tyrosine building blocks for Fmoc-based solid-phase peptide synthesis to allow convenient incorporation of these residues into peptides and proteins. Exposure of DEACM- and NPE-caged phosphopeptides to 420 nm light selectively releases the DEACM group without affecting the NPE-caged peptide. This then enables a subsequent irradiation event at 365 nm t...
Linear combinations of graph eigenvalues

Let µ1 (G) ≥ ...≥ µn (G) be the eigenvalues of the adjacency matrix of a graph G of order n, and G be the complement of G. Suppose F (G) is a fixed linear combination of µi (G), µn−i+1 (G) ,µ i G , and µn−i+1 G , 1 ≤ i ≤ k. It is shown that the limit lim n→∞ 1 n max {F (G ): v (G )= n} always exists. Moreover, the statement remains true if the maximum is taken over some restricted families like "Kr-free" or "r-partite" graphs. It is also shown that 29 + √ 329 42 n − 25 ≤ max v(G)=n µ1 (G )+ µ2 (G) ≤ 2 √ 3 n. This inequality answers in the negative a question of Gernert.
PROPERTY (FA) AND LATTICES IN SU(2,1)

In this paper we consider Property (FA) for lattices in SU(2,1). First, we prove that has Property (FA). We then prove that the arithmetic lattices in SU(2,1) of second type arising from congruence subgroups studied by Rapoport–Zink and Rogawski cannot split as a nontrivial free product with amalgamation; one such example is Mumford's fake projective plane. In fact, we prove that the fundamental group of any fake projective plane has Property (FA).
Spectroscopic Measurements of Shock-Layer Flows in an Arcjet Facility

Under two different test conditions, radiation emanating from the freestream and shock-layer flow over a 15.24-cm-diam blunt-body test article as measured in NASA Ames Research Center's 20 MW Aerodynamic Heating Facility Arcjet. The test gas was a mixture of air and argon. Spatially resolved emission spectra were obtained over a 2000-8900 A wavelength range using a charge-coupled device camera (1024 × 256 array) attached to a spectrograph. The optical system was calibrated using tungsten and deuterium radiation sources. Previously developed analytical tools were used to determine the following line-of-sight-averaged thermodynamic properties from the calibrated spectra: 1) rotational temperature of the freestream and 2) rotational and vibrational temperatures within the shock layer. Based on the variation in intensity of emission spectra along the stagnation streamline, shock standoff distance was determined. Two sets of data for each test condition were compared to evaluate the repeatability of measurements. Considering likely sources of errors, an uncertainty analysis was performed to estimate the error bounds of the determined properties
anti-Selective SMP-catalyzed direct asymmetric Mannich-type reactions: synthesis of functionalized amino acid derivatives

The first (S)-2-methoxymethylpyrrolidine (SMP)-catalyzed direct asymmetric Mannich-type reactions of unmodified aldehydes with N-PMP-protected α-imino ethyl glyoxylate are described. The reaction proceeded in a highly anti-selective manner (dr up to 19:1) with enantioselectivities between 74 and 92%.
Proline Sulfonamide‐Catalyzed, ­Domino Process for Asymmetric Synthesis of Amino‐ and Hydroxy‐Substituted Bicyclo[2.2.2]octanes

A generalized method for accessing highly functionalized amino-substituted bicyclo[2.2.2]octanes via p-dodecylphenylsulfonamide catalyst in a good enantio- and diastereoselective fashion has been developed. A discussion of the mechanistic underpinnings of this transformation is presented. Finally, an unexpected discovery enabling the extension of this protocol to the synthesis of OH-substituted bicyclo[2.2.2]octanes with encouraging levels of stereoselectivity is discussed.
Resisting Institutional Depression

The following essay by Art Bochner appeared in the April 2008 Spectra, a monthly publication of the National Communication Association, of which Bochner is President. Â©National Communication Association, 2008. Reprinted by permission.
Biochemical and behavioral studies of D1 dopamine receptors utilizing SCH 23390.

Previous research has demonstrated the existence of two distinct dopamine receptor subtypes (Kebabian & Calne, 1979; Creese et al., 1983), possessing unique pharmacologic and biochemical properties. D1 dopamine receptors stimulate adenylate cyclase activity (Hyttel, 1978), while D2 dopamine receptors inhibit this enzyme (Stoof and Kebabian, 1981; Onali et al., 1984; Battaglia et al., 1985). However, both receptor subtypes co-exist in many tissues making the determination of their respective physiological and behavioral roles difficult. All neuroleptics, commonly used drugs in the treatment of schizophrenia, have been shown to be either mixed D1/D2 dopamine receptor antagonists or selective D2 dopamine receptor antagonists. Thus, D2 dopamine receptors have been implicated as the site mediating the antipsychotic and antidopaminergic activity of neuroleptics (Creese et al., 1976; Seeman et al., 1976). By inference, D2 dopamine receptors have been considered to mediate dopaminergic agonists’ behavioral effects as well (Seeman, 1981).
A Novel Recombinant DNA System for High Efficiency Affinity Purification of Proteins in Saccharomyces cerevisiae.

Isolation of endogenous proteins from Saccharomyces cerevisiae has been facilitated by inserting encoding polypeptide affinity tags at the C-termini of chromosomal open reading frames (ORFs) using homologous recombination of DNA fragments. Tagged protein isolation is limited by a number of factors, including high cost of affinity resins for bulk isolation and low concentration of ligands on the resin surface, leading to low isolation efficiencies and trapping of contaminants. To address this, we have created a recombinant “CelTag” DNA construct from which PCR fragments can be created to easily tag C-termini of S. cerevisiae ORFs using selection for a nat1 marker. The tag has a C-terminal cellulose binding module to be used in the first affinity step. Microgranular cellulose is very inexpensive and has an effectively continuous ligand on its surface, allowing rapid, highly efficient purification with minimal background. Cellulose-bound proteins are released by specific cleavage of an included site for TEV protease, giving nearly pure product. The tag can be lifted from the recombinant DNA construct either with or without a 13x myc epitope tag between the target ORF and the TEV protease site. Binding of CelTag protein fusions to cellulose is stable to high salt, nonionic detergents, and 1 M urea, allowing stringent washing conditions to remove loosely associated components, as needed, before specific elution. It is anticipated that this reagent could allow isolation of protein complexes from large quantities of yeast extract, including soluble, membrane-bound, or nucleic acid-associated assemblies.
What Drives Deregulation? Economics and Politics of the Relaxation of Bank Branching Restrictions

This paper investigates private-interest, public-interest, and political-institutional theories of regulatory change to analyze state-level deregulation of bank branching restrictions. Using a hazard model, we find that interest group factors related to the relative strength of potential winners (large banks and small, bank-dependent firms) and losers (small banks and the rival insurance firms) can explain the timing of branching deregulation across states during the last quarter century. The same factors also explain congressional voting on interstate branching deregulation. While we find some support for each theory, the private interest approach provides the most compelling overall explanation of our results.
Trade Liberalization and Labor Market Dynamics

This paper estimates a structural dynamic equilibrium model of the Brazilian labor market in order to study trade-induced transitional dynamics. The model features a multi-sector economy with overlapping generations, heterogeneous workers, endogenous accumulation of sector-specific experience, and costly switching of sectors. The model's estimates yield median costs of mobility ranging from 1.4 to 2.7 times annual average wages, but a high dispersion of these costs across the population. In addition, sector-specific experience is imperfectly transferable across sectors, leading to additional barriers to mobility. Using the estimated model for counterfactual trade liberalization experiments, the main findings are: (1) there is a large labor market response following trade liberalization but the transition may take several years; (2) potential aggregate welfare gains are significantly reduced due to the delayed adjustment; (3) trade-induced welfare effects depend on initial sector of employment and on worker demographics such as age and education. The experiments also highlight the sensitivity of the transitional dynamics with respect to assumptions regarding the mobility of capital.
Queuing Models for Abstracting Interactions in Bacterial Communities

Microbial communities play a significant role in bioremediation, plant growth, human and animal digestion, global elemental cycles including the carbon-cycle, and water treatment. They are also posed to be the engines of renewable energy via microbial fuel cells, which can reverse the process of electrosynthesis. Microbial communication regulates many virulence mechanisms used by bacteria. Thus, it is of fundamental importance to understand interactions in microbial communities and to develop predictive tools that help control them, in order to aid the design of systems exploiting bacterial capabilities. This position paper explores how abstractions from communications, networking and information theory can play a role in understanding and modeling bacterial interactions. In particular, two forms of interactions in bacterial systems will be examined: electron transfer and quorum sensing . While the diffusion of chemical signals has been heavily studied, electron transfer occurring in living cells and its role in cell–cell interaction is less understood. Recent experimental observations open up new frontiers in the design of microbial systems based on electron transfer, which may coexist with the more well-known interaction strategies based on molecular diffusion. In quorum sensing, the concentration of certain signature chemical compounds emitted by the bacteria is used to estimate the bacterial population size, so as to activate collective behaviors. In this position paper, queuing models for electron transfer are summarized and adapted to provide new models for quorum sensing. These models are stochastic, and thus capture the inherent randomness exhibited by cell colonies in nature. It is shown that queuing models allow the characterization of the state of a single cell as a function of interactions with other cells and the environment, thus enabling the construction of an information theoretic framework, while being amenable to complexity reduction using methods based on statistical physics and wireless network design.
Identifying trends in the spatial errors of a regional climate model via clustering

Since their introduction in 1990, regional climate models (RCMs) have been widely used to study the impact of climate change on human health, ecology, and epidemiology. To ensure that the conclusions of impact studies are well founded, it is necessary to assess the uncertainty in RCMs. This is not an easy task because two major sources of uncertainties can undermine an RCM: uncertainty in the boundary conditions needed to initialize the model and uncertainty in the model itself. Using climate data for Southern Sweden over 45 years, in this paper, we present a statistical modeling framework to assess an RCM driven by analyses. More specifically, our scientific interest here is determining whether there exist time periods during which the RCM in consideration displays the same type of spatial discrepancies from the observations. The proposed model can be seen as an exploratory tool for atmospheric modelers to identify time periods that require a further in-depth examination. Focusing on seasonal average temperature, our model relates the corresponding observed seasonal fields to the RCM output via a hierarchical Bayesian statistical model that includes a spatio-temporal calibration term. The latter, which represents the spatial error of the RCM, is in turn provided with a Dirichlet process prior, enabling clustering of the errors in time. We apply our modeling framework to data from Southern Sweden spanning the period 1 December 1962 to 30 November 2007, revealing intriguing tendencies with respect to the RCM spatial errors of seasonal average temperature. Copyright © 2016 John Wiley & Sons, Ltd.
Portfolio optimization with stochastic dominance constraints

Abstract We consider the problem of constructing a portfolio of finitely many assets whose return rates are described by a discrete joint distribution. We propose a new portfolio optimization model involving stochastic dominance constraints on the portfolio return rate. We develop optimality and duality theory for these models. We construct equivalent optimization models with utility functions. Numerical illustration is provided.