cssi/SciSciGPT-SciSciNet huggingface dataset:
RETRACTED ARTICLE: All-Atom Molecular-Level Analysis of the Ballistic-Impact-Induced Densification and Devitrification of Fused Silica

All-atom molecular-level computations are carried out to infer the dynamic response and material microstructure/topology changes of fused silica subjected to ballistic impact by a hard projectile. The analysis was focused on the investigation of specific aspects of the dynamic response and of the microstructural changes such as the deformation of highly sheared and densified regions and the conversion of amorphous fused silica to SiO2 crystalline allotropic modifications (in particular, α-quartz and stishovite). The microstructural changes in question were determined by carrying out a post-processing atom-coordination procedure. This procedure suggested the formation of stishovite (and perhaps α-quartz) within fused silica during ballistic impact. To rationalize the findings obtained, the all-atom molecular-level computational analysis is complemented by a series of quantum-mechanics density functional theory (DFT) computations. The latter computations enable determination of the relative potential energies of the fused silica, α-quartz, and stishovite under ambient pressure (i.e., under their natural densities) as well as under imposed (as high as 50 GPa) pressures (i.e., under higher densities) and shear strains. In addition, the transition states associated with various fused-silica devitrification processes were identified. The results obtained are found to be in good agreement with their respective experimental counterparts.
Anatabine Significantly Decreases Nicotine Self-Administration

Nicotine addiction is associated with many lethal disorders (cancer, cardiovascular and pulmonary disease), and more effective medications to aid smoking cessation are urgently needed. Anatabine is 1 of the most abundant minor tobacco alkaloids, but relatively little is known about its interactions with the abuse-related effects of nicotine. The acute effects of anatabine or saline on nicotine- and foodmaintained responding were examined in 7 rhesus monkeys (Macaca mulatta). Nicotine (0.01 mg/kg/inj, base) and banana-flavored food pellets (1 g) were available under a second-order schedule (FR 2 [VR 16:S]). Anatabine or saline injections were administered 15 min before the 11:00 a.m. food selfadministration session began. Anatabine (0.18 –3.2 mg/kg, IM) dose-dependently reduced nicotine self-administration (0.01 mg/kg/inj) (p .036 – 0.0003). Food-maintained responding was decreased only at the highest dose of anatabine (3.2 mg/kg; p .003). Each monkey returned to baseline levels of nicotine self-administration after anatabine treatment, and there was no evidence of catheter malfunction. Next, the effects of anatabine and saline on the nicotine dose-effect curve (0.001-0.1 mg/kg/inj) were evaluated. Anatabine (0.32 and 1.0 mg/kg, IM) decreased the peak of the nicotine dose-effect curve (p .001 – p .0001), with no significant effect on food-maintained responding. The abuse liability of anatabine also was examined, and monkeys did not self-administer anatabine (0.0032– 0.32 mg/kg/inj) above saline levels. These findings are consistent with anatabine’s effects on nicotine self-administration in rats (Caine et al., 2014). These data suggest that anatabine could be an effective agonist medication for treatment of nicotine addiction.
Faster and shorter password-authenticated key exchange

This paper presents an improved password-based authenticated key exchange protocol in the common reference string model. Its security proof requires no idealized assumption (such as random oracles). The protocol is based on the GL framework introduced by Gennaro and Lindell, which generalizes the KOY key exchange protocol of Katz et al. Both the KOY and the GL protocols use (one-time) signatures as a non-malleability tool in order to prevent a man-in-the-middle attack against the protocol. The efficiency of the resulting protocol is negatively affected, since if we use regular signatures, they require a large amount of computation (almost as much as the rest of the protocol) and further computational assumptions. If one-time signatures are used, they substantially increase the bandwidth requirement. Our improvement avoids using digital signatures altogether, replacing them with faster and shorter message authentication codes. The crucial idea is to leverage as much as possible the non-malleability of the encryption scheme used in the protocol, by including various values into the ciphertexts as labels. As in the case of the GL framework, our protocol can be efficiently instantiated using either the DDH, Quadratic Residuosity or N-Residuosity Assumptions. For typical security parameters our solution saves as much as 12 Kbytes of bandwidth if one-time signatures are implemented in GL with fast symmetric primitives. If we use number-theoretic signatures in the GL framework, our solution saves several large exponentiations (almost a third of the exponentiations computed in the GL protocol). The end result is that we bring provable security in the realm of password-authenticated key exchange one step closer to practical.
A push/pop phenomenon for nonlinear systems

The author investigates performance limitations imposed by nonminimum phase characteristics of a nonlinear time-varying plant. A performance criterion is defined which, in the linear case, is analogous to minimizing the sensitivity over a given frequency band. It is shown that if the nonlinear plant is nonminimum phase, then the frequency-weighted sensitivity cannot be made arbitrarily small while keeping the overall sensitivity bounded. The nonminimum phasedness of the plant is stated in terms of deficiency in its range. These results extend the familiar push/pop phenomenon in sensitivity optimization to a nonlinear time-varying setting. >
Streaming lower bounds for approximating MAX-CUT

We consider the problem of estimating the value of max cut in a graph in the streaming model of computation. At one extreme, there is a trivial 2-approximation for this problem that uses only O(log n) space, namely, count the number of edges and output half of this value as the estimate for max cut value. On the other extreme, if one allows O(n) space, then a near-optimal solution to the max cut value can be obtained by storing an O(n)-size sparsifier that essentially preserves the max cut. An intriguing question is if poly-logarithmic space suffices to obtain a non-trivial approximation to the max-cut value (that is, beating the factor 2). It was recently shown that the problem of estimating the size of a maximum matching in a graph admits a non-trivial approximation in poly-logarithmic space.Our main result is that any streaming algorithm that breaks the 2-approximation barrier requires [EQUATION] space even if the edges of the input graph are presented in random order. Our result is obtained by exhibiting a distribution over graphs which are either bipartite or 1/2-far from being bipartite, and establishing that [EQUATION] space is necessary to differentiate between these two cases. Thus as a direct corollary we obtain that [EQUATION] space is also necessary to test if a graph is bipartite or 1/2-far from being bipartite. We also show that for any e > 0, any streaming algorithm that obtains a (1 + e)-approximation to the max cut value when edges arrive in adversarial order requires n1−O(e) space, implying that Ω(n) space is necessary to obtain an arbitrarily good approximation to the max cut value.
Probing Sea Quark and Gluon Polarization at STAR

One of the primary goals of the spin program at the Relativistic Heavy Ion Collider (RHIC) is to determine the polarization of the sea quarks and gluons in the proton. The polarization of the sea quarks is probed through the production of W−(+) bosons via the annihilation of ū+ d (d + u), at leading order. In this proceedings we report measurements of the single-spin asymmetry, AL, for W boson production at √ s = 510 GeV, and the new constraints these results place on the antiquark helicity distributions. Recent results on the longitudinal double-spin asymmetry, ALL, for inclusive and di-jet production at √ s = 200 GeV are also presented. The inclusive jet results provide the first experimental indication of non-zero gluon polarization in the x range probed at RHIC.
Infrastructure Investment Demands in Emerging Markets and Developing Economies

The authors have assembled 1960–2012 infrastructure stock data from 145 countries to estimate the demand for infrastructure services in emerging markets and developing economies. This paper identifies that the required resource flows to satisfy new demand while maintaining service for existing infrastructure amounts to $836 billion or 6.1 percent of current gross domestic product per year over the period 2014–20. The annual infrastructure investment gap for emerging markets and developing economies is $452 billion per year, which implies that emerging markets and developing economies should almost double their current spending. The paper also estimates that half of the spending should be allocated to maintenance of existing assets. Acknowledging the challenges to compare infrastructure investment estimates across different methodologies, the authors recognize this result as a lower bound estimate and compare the results with others available in the literature.
Sylvester---Gallai for Arrangements of Subspaces

In this work we study arrangements of k-dimensional subspaces $$V_1,\ldots ,V_n \subset \mathbb {C}^\ell $$V1,�,Vn�Cl. Our main result shows that, if every pair $$V_{a},V_b$$Va,Vb of subspaces is contained in a dependent triple (a triple $$V_{a},V_b,V_c$$Va,Vb,Vc contained in a 2k-dimensional space), then the entire arrangement must be contained in a subspace whose dimension depends only on k (and not on n). The theorem holds under the assumption that $$V_a \cap V_b = \{0\}$$Va�Vb={0} for every pair (otherwise it is false). This generalizes the Sylvester---Gallai theorem (or Kelly's theorem for complex numbers), which proves the $$k=1$$k=1 case. Our proof also handles arrangements in which we have many pairs (instead of all) appearing in dependent triples, generalizing the quantitative results of Barak et. al. (Proc Natl Acad Sci USA 110(48):19213---19219, 2013). One of the main ingredients in the proof is a strengthening of a theorem of Barthe (Invent Math 134(2):335---361, 1998) (from the $$k=1$$k=1 to $$k>1$$k>1 case) proving the existence of a linear map that makes the angles between pairs of subspaces large on average. Such a mapping can be found, unless there is an obstruction in the form of a low dimensional subspace intersecting many of the spaces in the arrangement (in which case one can use a different argument to prove the main theorem).
And how are the children? The effects of ideology and mediation on child custody law and children's well-being in the United States.

Recent innovations in American child custody law have affected both the substantive law and the procedures by which custody decisions are reached. Professor Bruch describes these developments, analyses their underpinnings in psychology and ideology, and identifies both intended and unrecognized effects of the dispute resolution process on the custody decision. She concludes that many new doctrines and procedures that have been widely assumed to benefit children, including joint custody and mediation, often disserve children's interests.
Who Takes the Blame? The Strategic Effects of Collateral Damage

Can civilians caught in civil wars reward and punish armed actors for their behavior? If so, do armed actors reap strategic benefits from treating civilians well and pay for treating them poorly? Using precise geo-coded data on violence in Iraq from 2004 through 2009, we show that both sides are punished for the collateral damage they inflict. Coalition killings of civilians predict higher levels of insurgent violence and insurgent killings predict less violence in subsequent periods. This symmetric reaction is tempered by preexisting political preferences; the anti-insurgent reaction is not present in Sunni areas, where the insurgency was most popular, and the anti-Coalition reaction is not present in mixed areas. Our findings have strong policy implications, provide support for the argument that information civilians share with government forces and their allies is a key constraint on insurgent violence, and suggest theories of intrastate violence must account for civilian agency.
Productivity growth in Europe

This paper tests whether structural or firm-specific characteristics contributed more to (labor) productivity growth in the European Union between 2003 and 2008. It combines the Amadeus firm-level data on productivity and firm characteristics with country-level data describing regulatory environments from the World Bank's Doing Business surveys, foreign direct investment data from Eurostat, infrastructure quality assessments from the Global Competitiveness Report, and credit availability from the World Development Indicators. It finds that among the 12 newest members of the European Union, country characteristics are most important for firm productivity growth, particularly the stock of inward foreign direct investment and the availability of credit. By contrast, among the more developed 15 elder European Union member countries, firm-level characteristics, such as industry, size, and international affiliation, are most important for growth. The quality of the regulatory environment, measured by Doing Business indicators, is importantly correlated with productivity growth in all cases. This finding suggests that European Union nations can realize significant benefits from improving regulations and encouraging inward and outward foreign direct investment.
Specification and correctness of lambda lifting

We present a formal and general specification of lambda lifting and prove its correctness with respect to a call-by-name operational semantics. We use this specification to prove the correctness of a lambda lifting algorithm similar to the one proposed by Johnsson. Lambda lifting is a program transformation that eliminates free variables from functions by introducing additional formal parameters to function definitions and additional actual parameters to function calls. This operation supports the transformation from a lexically-structured functional program into a set of recursive equations. Existing results provide specific algorithms and only limited correctness results. Our work provides a more general specification of lambda lifting (and related operations) that supports flexible translation strategies, which may result in new implementation techniques. Our work also supports a simple framework in which the interaction of lambda lifting and other optimizations can be studied and from which new algorithms might be obtained.
Water under a Changing and Uncertain Climate: Lessons from Climate Model Ensembles*

AbstractClimate change and rapidly rising global water demand are expected to place unprecedented pressures on already strained water resource systems. Successfully planning for these future changes requires a sound scientific understanding of the timing, location, and magnitude of climate change impacts on water needs and availability—not only average trends but also interannual variability and quantified uncertainties. In recent years, two types of large-ensemble runs of climate projections have become available: those from groups of more than 20 different climate models and those from repeated runs of several individual models. These provide the basis for novel probabilistic evaluation of both projected climate change and the resulting effects on water resources. Using a broad range of available ensembles, this research explores the spatial and temporal patterns of high confidence as well as uncertainty in projected river runoff, irrigation water requirements, basin storage yield, and cost estimates of...
Robust constraints on dark energy and gravity from galaxy clustering data

Galaxy clustering data provide a powerful probe of dark energy. We examine how the constraints on the scaled expansion history of the Universe, xh(z) =H(z)s (with s denoting the sound horizon at the drag epoch), and the scaled angular diameter distance, xd(z) =DA(z)/s, depend on the methods used to analyse the galaxy clustering data. We find that using the observed galaxy power spectrum, Pobsg(k), xh(z) and xd(z) are measured more accurately and are significantly less correlated with each other, compared to using only the information from the baryon acoustic oscillations (BAO) in Pobsg(k). Using the {xh(z), xd(z)} from Pobsg(k) gives a Dark Energy Task Force (DETF) dark energy figure of merit (FoM) approximately a factor of 2 larger than using the {xh(z), xd(z)} from BAO only; this provides a robust conservative method to go beyond BAO only in extracting dark energy information from galaxy clustering data. We find that a Stage IV galaxy redshift survey, with 0.7 < z < 2 over 15 000 (deg)2, can measure with high precision [where fg(z) and G(z) are the linear growth rate and factor of large-scale structure, respectively, and is the dimensionless normalization of Pobsg(k)], when redshift-space distortion information is included. The measurement of provides a powerful test of gravity, and significantly boosts the dark energy FoM when general relativity is assumed.
El coleccionismo: el rescate de las cosas y lo humano

Colecionismo: o resgate das coisas e do humano Proposta de uma reflexao aprofundada sobre o ato de colecionar, uma das pulsoes menos compreendidas pelo pensamento contemporâneo, aqui concebido como uma extensao humanizadora do Ser. O destino dos objetos e o nosso destino, porque sem eles nao existiriamos como seres verdadeiramente humanos. O artigo se apoia em teoricos como Walter Benjamin ou Hannah Arendt e se detem em romancistas que tem refletido sobre o colecionismo em suas distopias, em que o ser humano e tratado como um objeto.
Controlled Hopwise Averaging: Bandwidth/energy-efficient asynchronous distributed averaging for wireless networks

This paper addresses the problem of averaging numbers across a wireless network from an important, but largely neglected, viewpoint: bandwidth/energy efficiency. We show that existing distributed averaging schemes are inefficient, producing networked dynamical systems that evolve with wasteful communications. To improve efficiency, we develop Controlled Hopwise Averaging (CHA), a distributed asynchronous algorithm that attempts to “make the most” out of each transmission. Unlike the existing schemes, CHA fully exploits the broadcast nature of wireless medium and enables greedy, decentralized, feedback control of when to initiate an iteration. We show that CHA admits a common quadratic Lyapunov function for analysis and control, establish its exponential convergence, and characterize its worst-case convergence rate. Finally, through extensive simulation on random geometric graphs, we show that CHA is substantially more efficient than several existing schemes, requiring far fewer transmissions to complete an averaging task.
Are occupation numbers observable

Abstract The question of whether occupation numbers and momentum distributions of nucleons in nuclei are observables is considered from an effective field theory perspective. Field redefinitions lead to variations that imply the answer is negative, as illustrated in the interacting Fermi gas at low density. Implications for the interpretation of ( e , e ′ p ) experiments with nuclei are discussed.
Synthesis of nucleoside 3′-phosphonates via 3′-keto nucleosides

Abstract Nucleophilic addition of diethyl phosphite anion to several 2′- or 3′-keto nucleosides results in an efficient synthesis of 2′-hydroxy-2′-phosphono- or 3′-hydroxy-3′-phosphononucleosides. The stereochemistry of one such adduct, 3′α-diethylphosphono-3′β-hydroxy-5′-O-tritylthymidine, was determined by single crystal diffraction analysis. When the 5′-hydroxyl group is protected with groups that are not sterically demanding, the 3′ geminal hydroxy phosphonates undergo radical deoxygenation under modified Barton conditions to afford the reduced compounds in good yields. Removal of the remaining hydroxyl protecting groups, and hydrolysis of the phosphonate acid esters, then gives the parent nucleoside 3′-phosphonic acids.
sA-ANT: A Hybrid Optimization Algorithm for Multirobot Coalition Formation

Future critical missions will require intelligent systems that can autonomously form robust coalitions of heterogeneous robots. A novel hybrid coalition formation algorithm for spatially distributed real-world tasks in multirobot systems is presented, which combines ant colony optimization and a simulated annealing technique. The scalability of the algorithm is demonstrated by applying it to varying team sizes of up to 200 simulated heterogeneous robots. Experimental results show that the proposed algorithm generates better and higher quality coalitions when benchmarked against a heuristic coalition formation algorithm and two coalition formation algorithms that leverage an ant colony optimization approach.
Structural models for nickel electrode active mass

Abstract Raman spectroscopic data allow one to distinguish nickel electrode active mass, alpha- and beta-phase materials. Discharged active mass is not isostructural with beta-Ni(OH)2. This is contrary to the generally accepted model for the discharged beta phase of active mass. It is concluded that charged active mass displays a disordered and nonstoichiometric, non-closepacked structure of the , NiOOH structure type. Raman spectral data and X-ray diffraction data are analyzed and shown to be consistent with this structural model.
Cross-virtual concatenation for Ethernet-over-SONET/SDH networks

Ethernet-over-SONET/SDH (EoS) is a popular approach for interconnecting geographically distant Ethernet segments using a SONET/SDH transport infrastructure. It typically uses virtual concatenation (VC) for dynamic bandwidth management. The aggregate SONET/SDH bandwidth for a given EoS connection is obtained by “concatenating” a number of equal-capacity virtual channels. Together, these virtual channels form a virtually concatenated group (VCG). In this article, we introduce a new concatenation technique, referred to as cross-virtual concatenation (CVC), which involves the concatenation of virtual channels of heterogeneous capacities. We show that CVC can be implemented through a simple upgrade at the end node, thus utilizing the existing legacy SDH infrastructure. By employing CVC for EoS systems, we show that the SDH bandwidth can be harvested more efficiently than in conventional VC. We consider two problems associated with routing CVC connections: the connection establishment problem and the connection upgrade problem. The goal of the first problem is to compute a set of paths between two EoS end systems such that a total bandwidth demand and a constraint on the differential delay between the paths are satisfied. Among all feasible sets, the one that consumes the least amount of network bandwidth is selected. For this problem, we develop an integer linear program (ILP) and an efficient algorithm based on the sliding-window approach. For the connection upgrade problem, the goal is to augment an existing set of paths so as to increase the aggregate bandwidth, while continue to meet the differential-delay constraint. We model this problem as a flow-maximization problem with a constraint on the delay of the virtual channels with positive flow. We then consider the problem of path selection under imprecise network state information. Simulations are conducted to demonstrate the advantages of employing CVC and to evaluate the performance of the proposed algorithms.
Finsler manifolds with nonpositive flag curvature and constant S-curvature

The flag curvature is a natural extension of the sectional curvature in Riemannian geometry, and the S-curvature is a non-Riemannian quantity which vanishes for Riemannian metrics. There are (incomplete) non-Riemannian Finsler metrics on an open subset in R n with negative flag curvature and constant S-curva- ture. In this paper, we are going to show a global rigidity theorem that every Finsler metric with negative flag curvature and constant S-curvature must be Riemannian if the manifold is compact. We also study the nonpositive flag curvature case.
Fold assignments for amino acid sequences of the CASP2 experiment

New and newly extended methods for fold assignment were tested for their abilities to assign folds to amino acid target sequences of unknown three-dimensional structure. These target sequences, released through the CASP2 experiment, are not obviously related to any sequence of known three-dimensional (3D) structure. We assigned 3D folds to target sequences and filed these predictions with CASP2 before their 3D structures were released. The methods tested were (1) Environmental 3D profiles of Bowie and colleagues [Bowie, J.U., Luthy, R., Eisenberg, D. Science 253:164-170, 1991]; (2) A variation of this is termed Directional Profiles; (3) The H3P2 five-dimensional sequence-structure substitution matrix of Rice and Eisenberg [Rice, D., Eisenberg, D.J. Mol. Biol. 267:1026-1037, 1997]; and (4) The Sequence Derived Property methods of Fischer and Eisenberg [Fischer, D., Eisenberg, D. Prot. Sci. 5:947-955, 1996]. When the 3D structures of the sequences were released, 17 of our predictions were evaluated. Of these 17, we assigned high probabilities to 11, of which 9 were correct. Five of these correct predictions were of known 3D structures similar to the targets and four of these were of new folds. The evaluation demonstrated that our methods were effective in assigning the proper fold to more than half of the CASP2 targets with known folds (5/9) and also were able to detect half of the sequences that corresponded to no known folds (4/8). Even when the correct fold is assigned to a sequence, proper alignment of the sequence to the structure remains a challenge. Our methods were able to produce accurate alignments (< 1.2 mean residue shift error from the structural alignment) for four of the targets, including the particularly difficult alignment (only 7% residue identity in the structurally aligned regions) of the ferrochelatase sequence to the fold of a periplasmic binding protein.
Information content of the non-linear matter power spectrum

We use an ensemble of N-body simulations of the currently favoured (concordance) cosmological model to measure the amount of information contained in the non-linear matter power spectrum about the amplitude of the initial power spectrum. Two surprising results emerge from this study: (i) that there is very little independent information in the power spectrum in the translinear regime (k≃ 0.2 –0.8 h Mpc−1 at the present day) over and above the information at linear scales; and (ii) that the cumulative information begins to rise sharply again with increasing wavenumber in the non-linear regime. In the fully non-linear regime, the simulations are consistent with no loss of information during translinear and non-linear evolution. If this is indeed the case then the results suggest a picture in which translinear collapse is very rapid, and is followed by a bounce prior to virialization, impelling a wholesale revision of the HKLM–Peacock & Dodds formalism.
An analysis of first-order logics of probability

Abstract We consider two approaches to giving semantics to first-order logics of probability. The first approach puts a probability on the domain, and is appropriate for giving semantics to formulas involving statistical information such as “The probability that a randomly chosen bird flies is greater than 0.9.” The second approach puts a probability on possible worlds, and is appropriate for giving semantics to formulas describing degrees of belief such as “The probability that Tweety (a particular bird) flies is greater than 0.9.” We show that the two approaches can be easily combined, allowing us to reason in a straightforward way about statistical information and degrees of belief. We then consider axiomatizing these logics. In general, it can be shown that no complete axiomatization is possible. We provide axiom systems that are sound and complete in cases where a complete axiomatization is possible, showing that they do allow us to capture a great deal of interesting reasoning about probability.
Measuring the galaxy–galaxy-mass three-point correlation function with weak gravitational lensing

We discuss the galaxy-galaxy-mass three-point correlation function (GGM3PCF) and show how to measure it with weak gravitational lensing. The method entails choosing a large number of pairs of foreground lens galaxies and constructing a mean shear map with respect to their axes, by averaging the ellipticities of background source galaxies. An average mass map can be reconstructed from this shear map and this will represent the average mass distribution around pairs of galaxies. We show how this mass map is related to the projected GGM3PCF. Using a large N-body dark matter simulation populated with galaxies using the halo occupation distribution bias prescription, we compute these correlation functions, mass maps, and shear maps. The resultant mass maps are distinctly bimodal, tracing the galaxy centres and remaining anisotropic up to scales much larger than the galaxy separation. We estimate the signal-to-noise ratio of the reconstructed mass maps for a survey of depth similar to the Sloan Digital Sky Survey (SDSS) and conclude that the GGM3PCF should be measurable with the current SDSS weak-lensing data. Measurements of this three-point function, along with galaxy-galaxy lensing and galaxy auto-correlation functions, will provide new constraints on galaxy bias models.
Thermal Contact Conductance of Elastomeric Gaskets

channel model have been investigated. For radially outward  ow with Re = 5.5 3 10 and Ro = 0.24, and transverse ribs of various sizes up to D/e = p/e = 10 on the leading and trailing walls, the following conclusions may be drawn: 1) For a  xed rib con guration on the leading wall, increasing the size of the ribs on the trailing wall increases the heat (mass) transfer on the leading wall. 2) For a  xed rib con guration on the trailing wall, increasing the size of the ribs on the leading wall does not signi cantly affect the heat (mass) transfer on the trailing wall. 3) With rotation at a relatively high speed, the heat (mass) transfer on the leading wall is quite low, regardless of the sizes of the ribs on the leading and trailing walls.
Design of a Variable Thickness Plate to Focus Bending Waves

This paper describes the design of a thin plate whose thickness is tailored in order to focus bending waves to a desired location on the plate. Focusing is achieved by smoothly varying the thickness of the plate to create a type of lens, which focuses structure-borne energy. Damping treatment can then be positioned at the focal point to efficiently dissipate energy with a minimum amount of treatment. Numerical simulations of both bounded and unbounded plates show that the design is effective over a broad frequency range, focusing traveling waves to the same region of the plate regardless of frequency. This paper also quantifies the additional energy dissipated by local damping treatment installed on a variable thickness plate relative to a uniform plate.Copyright © 2012 by ASME
Dynamic Poisson Factorization

Models for recommender systems use latent factors to explain the preferences and behaviors of users with respect to a set of items (e.g., movies, books, academic papers). Typically, the latent factors are assumed to be static and, given these factors, the observed pref- erences and behaviors of users are assumed to be generated without order. These assumptions limit the explorative and predictive capabilities of such models, since users' interests and item popularity may evolve over time. To address this, we propose dPF, a dynamic matrix factorization model based on the recent Poisson factorization model for recommendations. dPF models the time evolving latent factors with a Kalman filter and the actions with Poisson distributions. We derive a scalable variational inference algorithm to infer the latent factors. Finally, we demonstrate dPF on 10 years of user click data from arXiv.org, one of the largest repository of scientific papers and a formidable source of information about the behavior of scientists. Empirically we show performance improvement over both static and, more recently proposed, dynamic recommendation models. We also provide a thorough exploration of the inferred posteriors over the latent variables.
Measurement of Intracavity Quantum Fluctuations of Light Using an Atomic Fluctuation Bolometer

The spectral noise power of photon number fluctuations inside a driven high-finesse Fabry-Perot optical resonator is measured through the resonator-enhanced momentum diffusion of ultracold atoms trapped within. Light-induced heating of the trapped atoms is quantified by their rate of Evaporation from a finite-depth intra cavity optical trap. The relevance of cavity-enhanced momentum diffusion to cavity-enhanced measurements of atomic ensembles is discussed.
“Integrating in” and exact superpotentials in 4d

Abstract We discuss integrating out matter fields and integrating in matter fields in four dimensional supersymmetric gauge theories. Highly nontrivial exact superpotentials can be easily obtained by starting from a known theory and integrating in matter.
The modal interpretation of algebraic quantum field theory

Abstract We show that Dieks' recent proposal for extending the modal interpretation to algebraic quantum field theory fails to yield a well-defined prescription for which observables in a local spacetime region possess definite values. On the other hand, we demonstrate that there is a well-defined and unique extension of the modal interpretation to the local algebras of quantum field theory (which may, however, face a serious difficulty in connection with ergodic field states).
The assembly line : self-assembling nanocars

Abstract Certain molecular structures that have controlled rolling properties on surfaces have been termed as nanocars. The syntheses of nanocars are generally multi-stepped. We report here the synthesis of two nanocars by a process resembling an assembly line where front and rear portions are attached using hydrogen bonding and metal complexation. Nanocars 1a and 2a,b were designed using 2-pyridone moieties for hydrogen bonding and terpyridyl ligands for metal complexation, respectively.
Dynamic characteristics of statically determinate space-truss platforms

The geometry of a class of statically determinate platforms is developed and vibration frequencies determined. Such configurations would allow shape control by changing member lengths to be accomplished with small forces. An additional advantage of a statically determinate structure is being free of thermal stress under any temperature distribution. Frequency comparisons between statically determinate and more conventional redundant platforms are presented. Vibration of curved platforms that could be used as antenna concepts is also investigated. Alternate concepts incorporating the statically determinate design but having improved dynamic characteristics are suggested.
Methodology Development and Physical Organic Chemistry: A Powerful Combination for the Advancement of Glycochemistry

This Perspective outlines work in the Crich group on the diastereoselective synthesis of the so-called difficult classes of glycosidic bond: the 2-deoxy-β-glycopyranosides, the β-mannopyranosides, the α-sialosides, the α-glucopyranosides, and the β-arabinofuranosides with an emphasis on the critical interplay between mechanism and methodology development.
Orbital Advection by Interpolation: A Fast and Accurate Numerical Scheme for Super-Fast MHD Flows

In numerical models of thin astrophysical disks that use a Eulerian scheme, gas orbits supersonically through a fixed grid. As a result the time step is sharply limited by the Courant condition. Also, because the mean flow speed with respect to the grid varies with position, the truncation error varies systematically with position. For hydrodynamic (unmagnetized) disks an algorithm called FARGO has been developed that advects the gas along its mean orbit using a separate interpolation substep. This relaxes the constraint imposed by the Courant condition, which now depends only on the peculiar velocity of the gas, and results in a truncation error that is more nearly independent of position. This paper describes a FARGO-like algorithm suitable for evolving magnetized disks. Our method is second-order-accurate on a smooth flow and preserves ∇B = 0 to machine precision. The main restriction is that B must be discretized on a staggered mesh. We give a detailed description of an implementation of the code and demonstrate that it produces the expected results on linear and nonlinear problems. We also point out how the scheme might be generalized to make the integration of other supersonic/superfast flows more efficient. Although our scheme reduces the variation of truncation error with position, it does not eliminate it. We show that the residual position dependence leads to characteristic radial variations in the density over long integrations.
Morphology of MgO(111) surfaces: artifacts associated with the faceting of polar oxide surfaces into neutral surfaces

Abstract It is shown by optical, atomic force, scanning and transmission electron microscopies that the MgO(111) surface does not facet into neutral (100) type planes upon annealing. The triangular pyramidal pits that Henrich [V.E. Henrich Surf. Sci., 57 (1976) 385] associates with the polar (111) surface faceting into (100) planes turn out to be artifacts of the acid etch used in the sample preparation process. It is shown that the pyramidal pits have facets sloped at 10.8±2.8° with respect to the (111) surface, corresponding to sets of vicinal surfaces. The pit edges are confirmed by transmission electron microscopy to be along the three equivalent 〈110〉-type directions.
Ionization Properties of Mixed Lipid Membranes: A Gouy-chapman Model of the Electrostatic-hydrogen Bond Switch

Abstract The dissociation state of phosphatidic acid (PA) in a lipid bilayer is governed by the competition of proton binding and formation of a hydrogen bond through a mechanism termed the electrostatic–hydrogen bond switch. This mechanism has been suggested to provide the basis for the specific recognition of PA by proteins. Even in bare lipid bilayers the electrostatic–hydrogen bond switch is present if the membrane contains lipids like phosphatidylethanolamine that act as hydrogen bond donors. In this case, the dissociation state (pKa) of PA depends strongly on membrane composition. In the present work we incorporate the electrostatic–hydrogen bond switch mechanism into the Gouy–Chapman model for a membrane that is composed of PA and a hydrogen bond-donating zwitterionic lipid. To this end, our model integrates into the Gouy–Chapman approach a recently suggested electrostatic model for zwitterionic lipids. Hydrogen bond formation is incorporated phenomenologically as an additional non-electrostatic interaction between the phosphomonoester headgroup of PA and the zwitterionic lipid headgroup. We express the energetics of the composite membrane in terms of a free energy functional whose minimization leads to a modified non-linear Poisson–Boltzmann equation that we have solved numerically. Our calculations focus on the influence of the membrane environment on the dissociation state of PA. This influence can be expressed as a shift of the second pKa of PA, which we calculate as function of membrane composition, following experimental observation. The shift is large and negative if PA is the minor component in the membrane, and it changes over four pH units as function of the mole fraction of PA in the membrane. In contrast, the shift of the second pKa of PA remains small and is always positive if the zwitterionic lipid is unable to act as hydrogen bond donor. Hence, we find that the electrostatic–hydrogen bond switch mechanism regulates the dissociation state of PA with much greater sensitivity than would be possible based on a pure electrostatic regulation through the membrane potential.
Thinking, Drinking, and Driving: Application of the Theory of Reasoned Action to DWI Prevention

This study drew upon the theory of reasoned action (TRA) to predict the intention to drive while intoxicated (DWI). Four hypotheses were tested using telephone survey data from a random sample of 1,259 adult residents of Bemalillo County, New Mexico. Results showed the TRA to be predictive across a diversity of social groups. Contrary to hypotheses, subjective norms were a more powerful predictor than attitudes, and the perceived severity of DWI penalties was positively correlated with DWI intention, a paradoxical result that was explained with reference to the social environment of likely DWI offenders. The results suggest that anti-DWI public-information campaigns should stress the importance of informal social influence against drunk driving, rather than merely the legal penalties for drinking and driving.
High resolution neutron capture and transmission measurements on 137 Ba and their impact on the interpretation of meteoric barium anomalies

We have made improved measurements of the neutron capture and total cross sections for {sup 137}Ba over a sufficiently wide range of energies so that the reaction rate at s-process temperatures (kT=6{endash}23 keV) can be determined solely from the data. These rates are crucial for the interpretation of recently discovered anomalies of Ba isotopes in silicon carbide grains from the Murchison meteorite. Recent stellar models of the s process are in agreement with the meteoric anomaly data for Ba only if the {sup 137}Ba(n,{gamma}) reaction rate is 20{percent} larger than the previously accepted rate. Our reaction rates at s-process temperatures are in agreement with the extrapolated reaction rate from the most recent previous measurement. Hence, our results uphold, and place on much firmer footing, the discrepancy between recent stellar models of the s-process and the meteoric anomaly data. {copyright} {ital 1998} {ital The American Physical Society}
Reingestion and Footprint Characteristics of the VAK 191B

During 1974 and 1975, the U.S. Navy and the Federal Ministry of Defense of the Federal Republic of Germany jointly flight tested the VFW-Fokker VAK 191B V/STOL aircraft. One of the primary objectives of this test program was to obtain full-scale reingestion and footprint data which could be directly compared with existing model scale data. An evaluation of the flight test data by the U.S. Navy and VFW-Fokker has demonstrated that the scaled-up model test results accurately predicted the reingestion and footprint characteristics of this aircraft. This paper summarizes the results of an investigation of the reingestion and footprint characteristics of the VAK 191B.
Can growth opportunities explain the diversification discount

We investigate the possibility that the diversification discount is due to differing growth opportunities between diversified and single-segment firms. We do this by comparing diversified business segments with individual single-segment same-industry firms of comparable growth opportunities. Using a sample of 230 diversifying firms from 1981 to 1997, we find a significant valuation discount in diversified firms even when we control for the difference in growth opportunities between diversified and single-segment firms. This result suggests that differing growth opportunities between diversified and single-segment firms cannot account for the diversification discount.
STAKEHOLDER TREATMENT AMONGST IPOs AND THE ACQUISITION OF RESOURCES FOR ENTREPRENEURIAL VENTURES

Entrepreneurs bring together the various stakeholders necessary to create new products and services; however, stakeholders face a high level of uncertainty when determining whether to invest their resources in the venture. This paper draws from signaling theory and stakeholder theory to explain how firms that have reputations for outstanding treatment of stakeholders send a signal to potential resource investors that reduces the uncertainty they perceive to be associated with the venture. Perceived uncertainty is reduced because of an enhanced ability to acquire necessary resources, a smaller probability that unexpected events will occur, an increased ability to plan for changes that do occur in the external environment, and the possibility that the strong stakeholder network itself may be a source of sustainable competitive advantage for the firm. While these ideas are applicable to entrepreneurial ventures at many stages, the context examined herein is firms that are preparing for an initial public offering because they have had sufficient time to establish reputations.
Design and Life-Cycle Considerations for Unconventional Reservoir Wells

This paper provides an overview of design and life-cycle considerations for certain unconventional-reservoir wells. An overview of unconventional-reservoir definitions is provided. Well design and life-cycle considerations are addressed from three aspects: upfront reservoir development, initial well completion, and well-life and long-term considerations. Upfront-reservoir-development issues discussed include well spacing, well orientation, reservoir stress orientations, and tubular metallurgy. Initial-well-completion issues include maximum treatment pressures and rates, treatment diversion, treatment staging, flowback and cleanup, and dewatering needs. Well-life and long-term discussions include liquid loading, corrosion, refracturing and associated fracture reorientation, and the cost of abandonment. These design considerations are evaluated with case studies for five unconventional-reservoir types: shale gas (Barnett shale), tight gas (Jonah feld), tight oil (Bakken play), coalbed methane (CBM) (San Juan basin), and tight heavy oil (Lost Hills field). In evaluating the life cycle and design of unconventional-reservoir wells, 'one size' does not fit all and valuable knowledge and a shortening of the learning curve can be achieved for new developments by studying similar, more-mature fields.
Very Low-Rate Variable-Length Channel Quantization for Minimum Outage Probability

We identify a practical vector quantizer design problem where any fixed-length quantizer (FLQ) yields non-zero distortion at any finite rate, while there is a variable-length quantizer (VLQ) that can achieve zero distortion with arbitrarily low rate. The problem arises in a t × 1 multiple-antenna fading channel where we would like to minimize the channel outage probability by employing beam forming via quantized channel state information at the transmitter (CSIT). It is well-known that in such a scenario, finite-rate FLQs cannot achieve the full-CSIT (zero distortion) outage performance. We construct VLQs that can achieve the full-CSIT performance with finite rate. In particular, with P denoting the power constraint of the transmitter, we show that the necessary and sufficient VLQ rate that guarantees the full-CSIT performance is Θ(1/P). We also discuss several extensions (e.g. to precoding) of this result.
The Total Synthesis of Brevetoxin B: A Twelve-Year Odyssey in Organic Synthesis

The total synthesis of brevetoxin B has been achieved recently after a long search for a suitable pathway. This twelve-year odyssey in synthetic organic chemistry was marked by several strategic and tactical routes, and resulted in numerous new synthetic methods. This article is a behind-thescenes account of the total synthesis of brevetoxin B, from its origins at the University of Pennsylvania to its completion at the University of California, San Diego, and The Scripps Research Institute, La Jolla, California.