cssi/SciSciGPT-SciSciNet huggingface dataset:
Synthesis of three carbon atom bridged 2,4-diaminopyrrolo[2,3-d]-pyrimidines as nonclassical dihydrofolate reductase inhibitors

A series of seven nonclassical three carbon atom bridged 2,4-diamino-5-substituted-pyrrolo[2,3-d]-pyrirnidines 1a-g were synthesized as potential inhibitors of dihydrofolate reductase. Selective oxidation of diols 7a-g affords α-hydroxy ketones 8a-g. Subsequent condensation with malononitrile gave the requisite 2-amino-3-cyano-4-substituted furan precursors 9a-g. Cyclocondensation with guanidine in refluxing ethanol in one step affords the three carbon atom bridged 2,4-diamino-5-substituted-pyrrolo[2,3-d]-pyrimidines 1a-g. Preliminary biological results indicated that these compounds showed moderate inhibitory activities against dihydrofolate reductases from Pneumocystis carinii, Toxoplasma gondii, Mycobacterium avium and rat liver with IC50 values in the 0.66 μM - 70.1 μM range and some compounds had marginal selectivity for T. gondii dihydrofolate reductase.
TIME-SERIES PHOTOMETRY OF STARS IN AND AROUND THE LAGOON NEBULA. I. ROTATION PERIODS OF 290 LOW-MASS PRE-MAIN-SEQUENCE STARS IN NGC 6530

We have conducted a long-term, wide-field, high-cadence photometric monitoring survey of ~50,000 stars in the Lagoon Nebula H II region. This first paper presents rotation periods for 290 low-mass stars in NGC 6530, the young cluster illuminating the nebula, and for which we assemble a catalog of infrared and spectroscopic disk indicators, estimated masses and ages, and X-ray luminosities. The distribution of rotation periods we measure is broadly uniform for 0.5 days < P < 10 days; the short-period cutoff corresponds to breakup. We observe no obvious bimodality in the period distribution, but we do find that stars with disk signatures rotate more slowly on average. The stars' X-ray luminosities are roughly flat with rotation period, at the saturation level (log LX /L bol ?3.3). However, we find a significant positive correlation between LX /L bol and corotation radius, suggesting that the observed X-ray luminosities are regulated by centrifugal stripping of the stellar coronae. The period-mass relationship in NGC 6530 is broadly similar to that of the Orion Nebula Cluster (ONC), but the slope of the relationship among the slowest rotators differs from that in the ONC and other young clusters. We show that the slope of the period-mass relationship for the slowest rotators can be used as a proxy for the age of a young cluster, and we argue that NGC 6530 may be slightly younger than the ONC, making it a particularly important touchstone for models of angular momentum evolution in young, low-mass stars.
Differentially en/decoded orthogonal space-time block codes with APSK signals

In this letter, we propose a differential en/decoding scheme for Alamouti's orthogonal space-time code using amplitude/phase-shift keying (STC-APSK) signals and two transmit antennas. It is compared with the differential en/decoding scheme using 16APSK and single transmit antenna. It is also compared with the differential en/decoding scheme for Alamouti's orthogonal space-time code using 16PSK (STC-16PSK) signals and two transmit antennas. We find that the performance of the differentially en/decoded STC-APSK with 4.5 b/s/Hz is significantly better than that of the differentially en/decoded 16APSK with 4 b/s/Hz, and is almost the same as that of the STC-16PSK with 4 b/s/Hz over Rayleigh flat fading channels.
Micromechanics of Deformation in Porous Liquid‐Phase‐Sintered Alumina under Hertzian Contact

A series of fine-grained porous alumina samples, with and without a liquid phase, were fabricated in compositions matched closely to commercially available alumina used as microelectronic substrates. Hertzian indentation on monolithic specimens of the glass-containing samples produced a greater quasi-ductile stress–strain response compared with that observed in the pure alumina. Maximum residual indentation depths, determined from surface profilometry, correlated with the stress–strain results. Moreover, microstructural observations from bonded interface specimens revealed significantly more damage in the form of microcracking and under extreme loading, pore collapse, in the glass-containing specimens. The absence of the typical twin faulting mechanism observed for larger-grained alumina suggests that the damage mechanism for quasi-ductility in these fine-grained porous aluminas was derived from the pores acting as a stress concentrator and the grain boundary glass phase providing a weak path for short crack propagation.
Misperceiving the Beliefs of Others: How Pluralistic Ignorance Contributes to the Persistence of Positive Security Analyst Reactions to the Adoption of Stock Repurchase Plans

We consider how a social psychological bias referred to as pluralistic ignorance occurs among security analysts and how this bias may lead to behavioral conformity and isomorphism in analysts' reactions to the adoption of a particular organizational policy, namely, stock repurchase plans. Our theory suggests why (1) there may be a systematic tendency for analysts to underestimate the extent to which other analysts share their reservations about repurchase plans (i.e., reservations about whether plans reflect well on the performance prospects of adopting firms), such that (2) analysts conform to other analysts and issue more positive earnings forecasts and stock recommendations in response to the adoption of repurchase plans despite having private reservations about whether the plans reflect well on adopting firms. We also contend that analysts are less likely to underestimate the extent to which others share their reservations about repurchase plans to the extent that they have frequent communication ties to other analysts. Whereas prior neoinstitutional research on conformity and isomorphism has primarily adopted a cognitive perspective in which actors conform to the behavior of others based on their understandings of a particular policy or practice (i.e., they take the value of the policy for granted or infer the value of the policy from others' prior decisions), we develop a social psychological perspective on isomorphism wherein actors imitate others based on their biased perceptions of others' beliefs about the policy. We also extend perspectives on institutional persistence by explaining why constituents may continue to publicly endorse a policy despite having private reservations about the policy's efficiency benefits.
Monetary policy, indeterminacy and learning

Abstract Forward-looking monetary models with Taylor-type interest rate rules are known to generate indeterminacies, with a potential dependence on extraneous ‘sunspots,’ for some structural and policy parameters. We investigate the stability of these solutions under adaptive learning, focusing on ‘common factor’ or ‘resonance frequency’ representations in which the observed sunspot has a suitable time-series structure. We consider specifications incorporating both lagged and expected inflation in the Phillips Curve, and both expected and inertial elements in the policy rule. We find that some policy rules can indeed lead to learnable sunspot solutions and we investigate the conditions under which this phenomenon arises.
C-mode real-time tomographic reflection for a matrix array ultrasound sonic flashlight.

Real Time Tomographic Reflection (RTTR), permits in situ visualization of tomographic images, so that natural hand-eye coordination can be employed directly during invasive procedures. The method merges the visual outer surface of the patient with a simultaneous scan of the patient’s interior, using a half-silvered mirror. A viewpoint-independent virtual image is reflected precisely into the proper location. When applied to ultrasound, we call the resulting RTTR device the sonic flashlight. We have previously implemented the sonic flashlight using conventional 2D ultrasound. In this paper we present the first images from a new sonic flashlight based on Real Time 3D (RT3D) ultrasound, which uses a matrix array to electronically steer the ultrasound beam at very high speed. We show in situ C-mode images, which are parallel to the face of the transducer, of the hand and the cardiac ventricles.
GENERALIZED MATHAI-QUILLEN TOPOLOGICAL SIGMA MODELS

A simple field theoretical approach to Mathai-Quillen topological field theories of maps X : MI→MT from an internal space to a target space is presented. As an example of applications of our formalism we compute by applying our formulas the action and Q-variations of the fields of two well-known topological systems: topological quantum mechanics and type-A topological sigma model.
THE REACTION OF β-KETOACIDS WITH ALLYLBORONATES

Allylboronates react with β-ketoacids to yield tertiary homoallylic β-hydroxycarboxylic acids. The reaction presumably proceeds via a bicyclic transition state. The β-carboxylic substituent enhances the rate of the reaction.
Coupling of twin rectangular supersonic jets

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Enhancing Security Value by Ownership Restrictions: Evidence from a Natural Experiment

We present new evidence from a natural experiment to show circumstances in which ownership restrictions can enhance value. Our evidence is based on multiple restricted bond issues by an emerging market issuer at 150 basis points lower than comparable bonds, resulting in a billion dollars saving. This is intriguing: how can an emerging market issuer with junk bond ratings obtain such low yields? We argue ownership restrictions enhance value since they enable an issuer to precommit to renegotiate efficiently with a favored clientele in the potential default states, thereby circumventing deadweight costs of prolonged negotiations, particularly when the restricted clientele also values the underlying collateral higher than other investors. Ownership restrictions can also result in a transfer of value from holders of unrestricted bonds to holders of restricted bonds because of implicit seniority of the latter. We empirically test and find support for both value enhancement and value transfer and show robustness to several alternative explanations. Our evidence suggests that firms can benefit from designing securities with ownership restrictions, by offering new securities exclusively to investors who value them the most.
Use and communication of probabilistic forecasts

Probabilistic forecasts are becoming more and more available. How should they be used and communicated? What are the obstacles to their use in practice? I review experience with five problems where probabilistic forecasting played an important role. This leads me to identify five types of potential users: Low Stakes Users, who don't need probabilistic forecasts; General Assessors, who need an overall idea of the uncertainty in the forecast; Change Assessors, who need to know if a change is out of line with expectatations; Risk Avoiders, who wish to limit the risk of an adverse outcome; and Decision Theorists, who quantify their loss function and perform the decision-theoretic calculations. This suggests that it is important to interact with users and to consider their goals. The cognitive research tells us that calibration is important for trust in probability forecasts, and that it is important to match the verbal expression with the task. The cognitive load should be minimized, reducing the probabilistic forecast to a single percentile if appropriate. Probabilities of adverse events and percentiles of the predictive distribution of quantities of interest seem often to be the best way to summarize probabilistic forecasts. Formal decision theory has an important role, but in a limited range of applications.
Analysis of a novel diffractive scanning-wire beam position monitor (BPM) for discriminative profiling of electron vs. X-ray beams

Recent numerical studies of Free Electron Lasers (FELs) operating in the Self Amplified Spontaneous Emission (SASE) regime indicate a large sensitivity of the gain to the degree of transverse overlap (and associated phase coherence) between the electron and photon beams traveling down the insertion device. Simulations of actual systems imply that accurate detection and correction for this relative loss of overlap, rather than correction for the absolute departure of the electron beam from a fixed axis, is the preferred function of an FEL amplifier's Beam Position Monitor (BPM) and corrector systems. In this note we propose a novel diffractive BPM with the capability of simultaneously detecting and resolving the absolute (and relative) transverse positions and profiles of electron and X-ray beams co-propagating through an undulator. We derive the equations governing the performance of the BPM and examine its predicted performance for the SLAC Linac Coherent Light Source (LCLS), viz., for profiling multi-GeV electron bunches co-propagating with one-to-several-hundred keV X-ray beams. Selected research and development (R&D) tasks for fabricating and testing the proposed BPM are discussed.
Religion and the Paradox of Racial Inequality Attitudes

There appears to be an interesting paradox in American attitudes toward racial inequality: while Americans almost universally see inequality as a social evil, they also consistently oppose government programs to remedy it. This discrepancy appears to result from accounts for the causes of inequality: if inequality is caused by individual failures, rather than structural conditions, then government solutions to racial inequality are unlikely. We examine the role of religion in the formation of attitudes concerning racial inequality for both blacks and whites. Using logistic regression on data from the 1996 General Social Survey, we find that the inclusion of African Americans and multiple religious traditions further complicates the story behind contemporary debates over attitudes pertaining to racial inequality.
Democracy, Redistribution and Inequality

Abstract In this paper we revisit the relationship between democracy, redistribution, and inequality. We first explain the theoretical reasons why democracy is expected to increase redistribution and reduce inequality, and why this expectation may fail to be realized when democracy is captured by the richer segments of the population; when it caters to the preferences of the middle class; or when it opens up disequalizing opportunities to segments of the population previously excluded from such activities, thus exacerbating inequality among a large part of the population. We then survey the existing empirical literature, which is both voluminous and full of contradictory results. We provide new and systematic reduced-form evidence on the dynamic impact of democracy on various outcomes. Our findings indicate that there is a significant and robust effect of democracy on tax revenues as a fraction of GDP, but no robust impact on inequality. We also find that democracy is associated with an increase in secondary schooling and a more rapid structural transformation. Finally, we provide some evidence suggesting that inequality tends to increase after democratization when the economy has already undergone significant structural transformation, when land inequality is high, and when the gap between the middle class and the poor is small. All of these are broadly consistent with a view that is different from the traditional median voter model of democratic redistribution: democracy does not lead to a uniform decline in post-tax inequality, but can result in changes in fiscal redistribution and economic structure that have ambiguous effects on inequality.
Uncertainty propagation in puff-based dispersion models using polynomial chaos

Atmospheric dispersion is a complex nonlinear physical process with numerous uncertainties in model parameters, inputs, source parameters, initial and boundary conditions. Accurate propagation of these uncertainties through the dispersion models is crucial for a reliable prediction of the probability distribution of the states and assessment of risk. A simple three-dimensional Gaussian puff-based dispersion model is used as a test case to study the effect of uncertainties in the model parameters and initial conditions on the output concentration. A polynomial chaos based approach is used to numerically investigate the evolution of the model output uncertainties due to initial condition and parametric uncertainties. The polynomial chaos solution is found to be an accurate approximation to ground truth, established by Monte Carlo simulation, while offering an efficient computational approach for large nonlinear systems with a relatively small number of uncertainties.
Quantum effects in Coulomb blockade

Abstract We review the quantum interference effects in a system of interacting electrons confined to a quantum dot. The review starts with a description of an isolated quantum dot. We discuss the random matrix theory (RMT) of the one-electron states in the dot, present the universal form of the interaction Hamiltonian compatible with the RMT, and derive the leading corrections to the universal interaction Hamiltonian. Next, we discuss a theoretical description of a dot connected to leads via point contacts. Having established the theoretical framework to describe such an open system, we discuss its transport and thermodynamic properties. We review the evolution of the transport properties with the increase of the contact conductances from small values to values ∼e2/πℏ. In the discussion of transport, the emphasis is put on mesoscopic fluctuations and the Kondo effect in the conductance.
Enantioselective catalysis with homochiral metal–organic frameworks

This tutorial review presents recent developments of homochiral metal–organic frameworks (MOFs) in enantioselective catalysis. Following a brief introduction of the basic concepts and potential virtues of MOFs in catalysis, we summarize three distinct strategies that have been utilized to synthesize homochiral MOFs. Framework stability and accessibility of the open channels to reagents are then addressed. We finally survey recent successful examples of catalytically active homochiral MOFs based on three approaches, namely, homochiral MOFs with achiral catalytic sites, incorporation of asymmetric catalysts directly into the framework, and post-synthetic modification of homochiral MOFs. Although still in their infancy, homochiral MOFs have clearly demonstrated their utility in heterogeneous asymmetric catalysis, and a bright future is foreseen for the development of practically useful homochiral MOFs in the production of optically pure organic molecules.
Polyfluorinated ligand-supported organometallic complexes of copper, silver, and gold*

The tris(pyrazolyl)borate (HB(3,5-(CF 3 ) 2 Pz) 3 ) − prepared using highly fluorinated 3,5-bis(trifluoromethyl)pyrazole and BH 4 − is an excellent supporting ligand for the stabi- lization of a number of rare organometallic complexes of coinage metals. For example, it has enabled the isolation of Cu(I), Ag(I), and Au(I) complexes of CO and ethylene as crys- talline solids. Syntheses, spectroscopic and structural features, and properties of (HB(3,5-(CF 3 ) 2 Pz) 3 )ML (M = Cu, Ag, Au; L = CO, C 2 H 4 ) are the main focus of this dis- cussion. Several metal adducts based on the tris(triazolyl)borate (HB(3,5-(CF 3 ) 2 Tz) 3 ) − sup- porting ligand as well as the cationic, coinage metal multi-alkene complexes containing the (SbF 6 ) − counterion are also discussed.
Determinants of Private Long-Term Care Insurance Purchase in Response to the Partnership Program

Objective To assess three possible determinants of individuals' response in their private insurance purchases to the availability of the Partnership for Long-Term Care (PLTC) insurance program: bequest motives, financial literacy, and program awareness. Data Sources The health and retirement study (HRS) merged with data on states' implementation of the PLTC program. Study Design Individual-level decision on private long-term care insurance is regressed on whether the PLTC program is being implemented for a given state-year, asset dummies, policy determinant variable, two-way and three-way interactions of these variables, and other controls, using fixed effects panel regression. Data Extraction Methods Analysis used a sample between 50 and 69 years of age from 2002 to 2010, resulting in 12,695 unique individuals with a total of 39,151 observations. Principal Findings We find mild evidence that intent to bequest influences individual purchase of insurance. We also find that program awareness is necessary for response, while financial literacy notably increases responsiveness. Conclusions Increasing response to the PLTC program among the middle class (the stated target group) requires increased efforts to create awareness of the program's existence and increased education about the program's benefits, and more generally, about long-term care risks and needs.
Interactive Visualization of Particle Beams for Accelerator Design

We describe a hybrid data-representation and rendering technique for visualizing large-scale particle data generated from numerical modeling of beam dynamics. The basis of the technique is mixing volume rendering and point rendering according to particle density distribution, visibility, and the user's instruction. A hierarchical representation of the data is created on a parallel computer, allowing real-time partitioning into high-density areas for volume rendering, and low-density areas for point rendering. This allows the beam to be interactively visualized while preserving the fine structure usually visible only with slow point-based rendering techniques.
Regioselective cleavage of O-benzyl-N-arylamidoximes: synthesis of N-aryl amidines and amidoximes

O-Benzyl-N-arylamidoximes have been regioselectively deprotected to provide either N-aryl amidines or amidoximes. As a result, the targeted compounds can now be prepared using palladium-catalyzed N-arylation chemistry.
Hydrogen evolution from organic “hydrides”

Benzimidazolines (dihydrobenzimidazoles) are shown for the first time to eliminate hydrogen (H2) by catalyzed reaction with protic compounds.
Misassembly detection using paired-end sequence reads and optical mapping data.

Motivation: A crucial problem in genome assembly is the discovery and correction of misassembly errors in draft genomes. We develop a method called misSEQuel that enhances the quality of draft genomes by identifying misassembly errors and their breakpoints using paired-end sequence reads and optical mapping data. Our method also fulfills the critical need for open source computational methods for analyzing optical mapping data. We apply our method to various assemblies of the loblolly pine, Francisella tularensis, rice and budgerigar genomes. We generated and used stimulated optical mapping data for loblolly pine and F.tularensis and used real optical mapping data for rice and budgerigar. Results: Our results demonstrate that we detect more than 54% of extensively misassembled contigs and more than 60% of locally misassembled contigs in assemblies of F.tularensis and between 31% and 100% of extensively misassembled contigs and between 57% and 73% of locally misassembled contigs in assemblies of loblolly pine. Using the real optical mapping data, we correctly identified 75% of extensively misassembled contigs and 100% of locally misassembled contigs in rice, and 77% of extensively misassembled contigs and 80% of locally misassembled contigs in budgerigar. Availability and implementation: misSEQuel can be used as a post-processing step in combination with any genome assembler and is freely available at http://www.cs.colostate.edu/seq/. Contact: ude.etatsoloc.sc@ilggum Supplementary information: Supplementary data are available at Bioinformatics online.
The Political Economy of Monetary Institutions in Brazil: The Limits of the Inflation-targeting Strategy, 1999–2005

Abstract This paper suggests that the time-inconsistency approach is inadequate to analyze the political economy of monetary policy in Brazil. The paper develops an alternative theory that emphasizes distributive conflict, and argues that building credibility with a fixed exchange rate and through inflation-targeting was not central for stabilization. A contested-terrain analysis of the Brazilian case suggests that the current monetary regime benefits financial or rentier interests while the manufacturing sector and workers bear the costs of this policy.
How does competition affect the performance of MFIs ? evidence from Bangladesh

Over the past 20 years, Bangladesh has witnessed strong competition among microfinance institutions. Using program-level panel data from 2005-2010, this paper studies the microfinance institutions' recent competitive roles in their pricing of products, targeting strategies and portfolio shifts, as well as their ability to recover loans. The findings do not support the view that newer microfinance institutions are less risk-averse in their targeting, or that increased borrowing among households due to microfinance institution competition has lowered recovery rates. There is also a considerable urban-rural distinction; although newer microfinance institutions tend to attract riskier clients in urban areas, the opposite is true in rural areas. Loan recovery rates are also the highest among the newest microfinance institutions for women in rural areas, suggesting that microfinance institutions may offer distinct products in these areas to attract better-risk clients. The portfolio of newer microfinance institutions also has a greater share of lending for agriculture, and fewer savings products.
Histotripsy beyond the intrinsic cavitation threshold using very short ultrasound pulses: microtripsy

Histotripsy produces tissue fractionation through dense energetic bubble clouds generated by short, high-pressure, ultrasound pulses. Conventional histotripsy treatments have used longer pulses from 3 to 10 cycles, wherein the lesionproducing bubble cloud generation depends on the pressurerelease scattering of very high peak positive shock fronts from previously initiated, sparsely distributed bubbles (the shockscattering mechanism). In our recent work, the peak negative pressure (P-) for generation of dense bubble clouds directly by a single negative half cycle, the intrinsic threshold, was measured. In this paper, the dense bubble clouds and resulting lesions (in red blood cell phantoms and canine tissues) generated by these supra-intrinsic threshold pulses were studied. A 32-element, PZT-8, 500-kHz therapy transducer was used to generate very short (<;2 cycles) histotripsy pulses at a pulse repetition frequency (PRF) of 1 Hz and P- from 24.5 to 80.7 MPa. The results showed that the spatial extent of the histotripsy-induced lesions increased as the applied P- increased, and the sizes of these lesions corresponded well to the estimates of the focal regions above the intrinsic cavitation threshold, at least in the lower pressure regime (P- = 26 to 35 MPa). The average sizes for the smallest reproducible lesions were approximately 0.9 - 1.7 mm (lateral - axial), significantly smaller than the -6-dB beamwidth of the transducer (1.8 - 4.0 mm). These results suggest that, using the intrinsic threshold mechanism, well-confined and microscopic lesions can be precisely generated and their spatial extent can be estimated based on the fraction of the focal region exceeding the intrinsic cavitation threshold. Because the supra-threshold portion of the negative half cycle can be precisely controlled, lesions considerably less than a wavelength are easily produced, hence the term microtripsy.
A Low-Cost, Low-Power Consumption, Miniature Laser-Induced Fluorescence System for DNA Detection on a Microfluidic Device

With a focus on low-cost and low-power consumption, a miniature laser-induced fluorescence (LIF) detection system was assembled using a 635 nm red diode laser as the excitation source and a photodiode element coupled with an operational amplifier for signal collection. The primary elements of the miniature system, namely the laser and the detection system, cost a combined $70 and required only 270 mW of power for operation. When compared to conventional systems assembled using an argon-ion laser source and a photomultiplier tube, this represents a 98% decrease in the cost, and greater than 5000-fold decrease in power consumption. Quantitation of DNA on microdevices using the miniature LIF detection system was also performed with an error of less than 15%. This detection system is a step in the direction of commercializing microfluidic instrumentation by reducing the cost and power required for operation.
Effect of Processing on Microstructure and Mechanical Behavior of Magnesium Oxide

Polycrystalline MgO specimens were fabricated from two powders by hot-pressing in graphite or alumina dies and annealing in air, in vacuum, or within the graphite die in vacuum. Parameters affected were density, grain size, and visual appearance, which was considered to be dependent on grain boundary structure. The formation of a boundary liquid phase with one type of powder tended to eliminate the effect of the processing variables. The character (microstructure) of the specimens was correlated with their mechanical behavior in compression at a constant strain rate at 1200°C.
New studies on adaptive predictive coding of images using multiplicative autoregressive models

The authors introduce two new one-dimensional multiplicative autoregressive (MAR) models for adaptive predictive coding of digitized images. The proposed scheme offers a number of advantages. These include easy implementability, a high signal-to-noise ratio at a moderate bit rate, and guaranteed stability of the predictive coder. Results of extensive experimental studies are presented. >
Core-Structure-Motivated Design of Iminium–Enolate Organocascade Reactions: Enantioselective Syntheses of 5,6-Dihydroindolizines

This highly efficient method affords diverse substituted dihydroindolizines with high enantioselectivities via the title cascade reaction by using simple starting materials.
Simultaneous B and L Violation: New Signatures from RPV-SUSY

Studies of R-parity violating (RPV) supersymmetry typically assume that nucleon stability is protected by approximate baryon number (B) or lepton number (L) conservation. We present a new class of RPV models that violate B and L simultaneously (BLRPV), without inducing rapid nucleon decay. These models feature an approximate Z 2×Z 2×Z 2 flavorsymmetry,whichforbids2-bodynucleondecayandensuresthatflavor antisymmetric LLE c couplings are the only non-negligible L-violating operators. Nucleons are predicted to decay through N → Keμν and n → eμν; the resulting bounds on RPV couplings are rather mild. Novel collider phenomenology arises because the superpartners can decay through both L-violating and B-violating couplings. This can lead to, for example, final states with high jet multiplicity and multiple leptons of different flavor, or a spectrum in which depending on the superpartner, either B or L violating decays dominate. BLRPV can also provide a natural setting for displaced ν → μe decays, which evade many existing collider searches for RPV supersymmetry.
A novel intelligent textile technology based on silicon flexible skins

This paper reports the successful prototype development of a novel intelligent textile technology based on the integration of silicon flexible skins with regular textiles. This novel approach enables the embedding of sensing and computational components into textiles without significantly compromising the flexibility and wearable properties. Silicon flexible skins comprised of arrays of silicon islands integrated with boron-doped strain gauges and metal pads were successfully fabricated using micromachining techniques. Prototypes of intelligent textiles were developed by stitching the silicon flexible skins onto the surface of textiles. The preliminary tests demonstrated excellent durability of the prototypes. The strain experienced by the silicon islands was monitored in real-time using the integrated strain gauges when the prototypes were mechanically deformed. These strain data provide valuable information for the further optimization, and the next stage of development, of this intelligent textile technology.
Optical arbitrary waveform generation and characterization using spectral line-by-line control

This paper demonstrates optical arbitrary waveform generation (O-AWG) and its characterization using spectral line-by-line control with high-resolution grating-based pulse shapers. Such integrated capabilities are the enabling techniques for high-fidelity O-AWG.
On the achievable rate of the fading dirty paper channel with imperfect CSIT

The problem of dirty paper coding (DPC) over the (multi-antenna) fading dirty paper channel (FDPC) Y = H(X + S) + Z is considered when there is imperfect knowledge of the channel state information H at the transmitter (CSIT). The case of FDPC with positive definite (p.d.) input covariance matrix was studied by the authors in a recent paper, and here the more general case of positive semi-definite (p.s.d.) input covariance is dealt with. Towards this end, the choice of auxiliary random variable is modified. The algorithms for determination of inflation factor proposed in the p.d. case are then generalized to the case of p.s.d. input covariance. Subsequently, the largest DPC-achievable high-SNR (signal-to-noise ratio) scaling factor over the no-CSIT FDPC with p.s.d. input covariance matrix is derived. This scaling factor is seen to be a non-trivial generalization of the one achieved for the p.d. case. Next, in the limit of low SNR, it is proved that the choice of all-zero inflation factor (thus treating interference as noise) is optimal in the ‘ratio’ sense, regardless of the covariance matrix used. Further, in the p.d. covariance case, the inflation factor optimal at high SNR is obtained when the number of transmit antennas is greater than the number of receive antennas, with the other case having been already considered in the earlier paper. Finally, the problem of joint optimization of the input covariance matrix and the inflation factor is dealt with, and an iterative numerical algorithm is developed.
The hydrodynamics of swimming microorganisms

Cell motility in viscous fluids is ubiquitous and affects many biological processes, including reproduction, infection and the marine life ecosystem. Here we review the biophysical and mechanical principles of locomotion at the small scales relevant to cell swimming, tens of micrometers and below. At this scale, inertia is unimportant and the Reynolds number is small. Our emphasis is on the simple physical picture and fundamental flow physics phenomena in this regime. We first give a brief overview of the mechanisms for swimming motility, and of the basic properties of flows at low Reynolds number, paying special attention to aspects most relevant for swimming such as resistance matrices for solid bodies, flow singularities and kinematic requirements for net translation. Then we review classical theoretical work on cell motility, in particular early calculations of swimming kinematics with prescribed stroke and the application of resistive force theory and slender-body theory to flagellar locomotion. After examining the physical means by which flagella are actuated, we outline areas of active research, including hydrodynamic interactions, biological locomotion in complex fluids, the design of small-scale artificial swimmers and the optimization of locomotion strategies. (Some figures in this article are in colour only in the electronic version) This article was invited by Christoph Schmidt.
SURFACE CLEANING AND ADSORBATE LAYER FORMATION : DUAL ROLE OF ALKYLAMINES IN THE FORMATION OF SELF-ASSEMBLED MONOLAYERS ON CUPRATE SUPERCONDUCTORS

The development of monolayer adsorption chemistry for superconductor surfaces is particularly important for a number of practical and fundamental reasons. As high-T{sub c} superconductors begin to approach the marketplace in areas of communications, power industries, medical applications, and scientific instrumentation, the development of new soft chemistry approaches for the surface modification of these technologically relevant electronic materials becomes increasingly important. Monolayer adsorption chemistry has been developed extensively for electronic materials such as metals, semiconductors, and insulators. These methodologies have been expanded recently to include a variety of high-temperature superconductors (HTSCs). The authors describe a series of new X-ray photoelectron spectroscopy (XPS), four-point conductivity, critical current, atomic absorption spectroscopy (AAS), grazing angle infrared spectroscopy, and GE--MS experiments, which lead the suggestion that an entirely different mechanism is involved in the formation of HTSC-localized monolayers. According to the new model, the amine reagents serve two chemically distinct roles. In the initial phase, the degraded superconductor exteriors is etched away with the help of the amine compounds. The etching process proceeds to the point where fresh YBa{sub 2}Cu{sub 3}O{sub 7} is exposed, and only at this point do the amines adsorb and remain at the YBa{sub 2}Cu{sub 3}O{sub 7} surface. As the adsorptionmore » process continues, there is an accumulation of an organized monolayer at the surface, which prevents further etching of the YBa{sub 2}Cu{sub 3}O{sub 7} material.« less
Real polynomial diffeomorphisms with maximal entropy: Tangencies

Like the Henon diffeomorphisms of R2, the quadratic maps of R, have also played a central role in the field of dynamical systems. These two families of dynamical systems fit together naturally, which raises the question of the extent to which the dynamics is similar. One difference is that our knowledge of these quadratic maps is much more thorough than our knowledge of these quadratic diffeomorphisms. Substantial progress in the theory of quadratic maps has led to a rather complete theoretical picture of their dynamics and an understanding of how the dynamics varies with the parameter. Despite significant recent progress in the theory of Henon diffeomorphisms, due to Benedicks and Carleson and many others, there are still many phenomena that are not nearly so well understood in this two-dimensional setting as they are for quadratic maps. One phenomenon which illustrates the difference in the extent of our knowledge in dimensions one and two is the dependence of the complexity of the system on parameters. In one dimension the nature of this dependence is understood, and the answer is summarized by the principle of monotonicity. Loosely stated, this is the assertion that the complexity of fa does not
High performance n-type carbon nanotube field-effect transistors with chemically doped contacts.

Short channel (80 nm) n-type single-walled carbon nanotube (SWNT) field-effect transistors (FETs) with potassium (K) doped source and drain regions and high-K gate dielectrics (ALD HfO2) are obtained. For nanotubes with diameter 1.6 nm and band gap 0.55 eV, we obtain n-MOSFET-like devices exhibiting high on-currents due to chemically suppressed Schottky barriers at the contacts, subthreshold swing of 70 mV/decade, negligible ambipolar conduction, and high on/off ratios up to 106 at a bias voltage of 0.5 V. The results compare favorably with the state-of-the-art silicon n-MOSFETs and demonstrate the potential of SWNTs for future complementary electronics. The effects of doping level on the electrical characteristics of the nanotube devices are discussed. Single-walled carbon nanotubes (SWNTs) are promising for future high performance electronics such as field effect transistors (FETs) owing to their various unique properties including ballistic transport with relatively long mean free paths and high compatibility with high- dielectrics imparted by their unique chemical bonding and surface stability. 1-12 While much has been done to achieve high performance p-type nanotube FETs through contact optimization, dielectric integration and lateral scaling, progress on n-FETs has been slow partly due to the difficulty in affording low Schottky (SB) contacts for high on-states and at the same time achieving high on/off ratios with small diameter (or large band gap) tubes. 7 Here, by invoking chemical doping, high- dielectrics, and new device design, we demonstrate n-type SWNT FETs with performance matching or approaching the best p-type nanotube FETs and surpassing the state-of-the-art Si n-MOSFET.
Gauge symmetries, topology, and quantisation

The following two loosely connected sets of topics are reviewed in these lecture notes: 1) Gauge invariance, its treatment in field theories and its implications for internal symmetries and edge states such as those in the quantum Hall effect. 2) Quantisation on multiply connected spaces and a topological proof the spin‐statistics theorem which avoids quantum field theory and relativity. Under 1), after explaining the meaning of gauge invariance and the theory of constraints, we discuss boundary conditions on gauge transformations and the definition of internal symmetries in gauge field theories. We then show how the edge states in the quantum Hall effect can be derived from the Chern‐Simons action using the preceding ideas. Under 2), after explaining the significance of fibre bundles for quantum physics, we review quantisation on multiply connected spaces in detail, explaining also mathematical ideas such as those of the universal covering space and the fundamental group. These ideas are then used to prove the aforementioned topological spin‐statistics theorem.
The complexity of causality and responsibility for query answers and non-answers

An answer to a query has a well-defined lineage expression (alternatively called how-provenance) that explains how the answer was derived. Recent work has also shown how to compute the lineage of a non-answer to a query. However, the cause of an answer or non-answer is a more subtle notion and consists, in general, of only a fragment of the lineage. In this paper, we adapt Halpern, Pearl, and Chockler's recent definitions of causality and responsibility to define the causes of answers and non-answers to queries, and their degree of responsibility. Responsibility captures the notion of degree of causality and serves to rank potentially many causes by their relative contributions to the effect. Then, we study the complexity of computing causes and responsibilities for conjunctive queries. It is known that computing causes is NP-complete in general. Our first main result shows that all causes to conjunctive queries can be computed by a relational query which may involve negation. Thus, causality can be computed in PTIME, and very efficiently so. Next, we study computing responsibility. Here, we prove that the complexity depends on the conjunctive query and demonstrate a dichotomy between PTIME and NP-complete cases. For the PTIME cases, we give a non-trivial algorithm, consisting of a reduction to the max-flow computation problem. Finally, we prove that, even when it is in PTIME, responsibility is complete for LOGSPACE, implying that, unlike causality, it cannot be computed by a relational query.
PIRACY ON THE SILVER SCREEN

Using survey data on movie consumption by about 500 University of Pennsylvania undergraduate students, we ask whether unpaid consumption of movies displaces paid consumption. A variety of cross-sectional and longitudinal empirical approaches show large and statistically significant evidence of displacement. In the most appropriate empirical specification, we find that unpaid first consumption reduces paid consumption by about 1 unit. Unpaid second consumption has a smaller effect, about 0.20 units. Our analysis indicates that unpaid consumption, which makes up 5.2 per cent of movie viewing in our sample, reduced paid consumption in our sample by 3.5 per cent.
Fast dimension reduction using Rademacher series on dual BCH codes

The Fast Johnson-Lindenstrauss Transform (FJLT) was recently discovered by Ailon and Chazelle as a novel technique for performing fast dimension reduction with small distortion from ed2 to ed2 in time O(max{d log d,k3}). For k in [Ω(log d), O(d1/2)] this beats time O(dk) achieved by naive multiplication by random dense matrices, an approach followed by several authors as a variant of the seminal result by Johnson and Lindenstrauss (JL) from the mid 80's. In this work we show how to significantly improve the running time to O(d log k) for k = O(d1/2−Δ), for any arbitrary small fixed Δ. This beats the better of FJLT and JL. Our analysis uses a powerful measure concentration bound due to Talagrand applied to Rademacher series in Banach spaces (sums of vectors in Banach spaces with random signs). The set of vectors used is a real embedding of dual BCH code vectors over GF(2). We also discuss the number of random bits used and reduction to e1 space. The connection between geometry and discrete coding theory discussed here is interesting in its own right and may be useful in other algorithmic applications as well.
Mean-Field Driven First-Order Phase Transitions in Systems with Long-Range Interactions

We consider a class of spin systems on ℤ d with vector valued spins (S x ) that interact via the pair-potentials J x,y S x ⋅S y . The interactions are generally spread-out in the sense that the J x,y 's exhibit either exponential or power-law fall-off. Under the technical condition of reflection positivity and for sufficiently spread out interactions, we prove that the model exhibits a first-order phase transition whenever the associated mean-field theory signals such a transition. As a consequence, e.g., in dimensions d≥3, we can finally provide examples of the 3-state Potts model with spread-out, exponentially decaying interactions, which undergoes a first-order phase transition as the temperature varies. Similar transitions are established in dimensions d = 1,2 for power-law decaying interactions and in high dimensions for next-nearest neighbor couplings. In addition, we also investigate the limit of infinitely spread-out interactions. Specifically, we show that once the mean-field theory is in a unique “state,” then in any sequence of translation-invariant Gibbs states various observables converge to their mean-field values and the states themselves converge to a product measure.
On mesh-particle techniques

The treatment of dilute solid (or liquid) phases via Lagrangian particles within mesh-based gas-dynamics (or hydrodynamic) codes is common in computational fluid dynamics. While these techniques work very well for a large spectrum of physical parameters, in some cases, notably for very light or very heavy particles, numerical instabilities appear. The present paper examines ways of mitigating these instabilities, and summarizes important implementational issues.
Bootstrap Percolation on Infinite Trees and Non-Amenable Groups

Bootstrap percolation on an arbitrary graph has a random initial configuration, where each vertex is occupied with probability $p$, independently of each other, and a deterministic spreading rule with a fixed parameter $k$: if a vacant site has at least $k$ occupied neighbours at a certain time step, then it becomes occupied in the next step. This process is well studied on ${\mathbb Z}^d$; here we investigate it on regular and general infinite trees and on non-amenable Cayley graphs. The critical probability is the infimum of those values of $p$ for which the process achieves complete occupation with positive probability. On trees we find the following discontinuity: if the branching number of a tree is strictly smaller than $k$, then the critical probability is 1, while it is $1-1/k$ on the $k$-ary tree. A related result is that in any rooted tree $T$ there is a way of erasing $k$ children of the root, together with all their descendants, and repeating this for all remaining children, and so on, such that the remaining tree $T'$ has branching number $\mbox{\rm br}(T')\leq \max\{\mbox{\rm br}(T)-k,\,0\}$. We also prove that on any $2k$-regular non-amenable graph, the critical probability for the $k$-rule is strictly positive.