cssi/SciSciGPT-SciSciNet huggingface dataset:
Busemann points of infinite graphs

We provide a geometric condition which determines whether or not every point on the metric boundary of a graph with the standard path metric is a Busemann point, that is, it is the limit point of a geodesic ray. We apply this and a related condition to investigate the structure of the metric boundary of Cayley graphs. We show that groups such as the braid group and the discrete Heisenberg group have boundary points of the Cayley graph which are not Busemann points when equipped with their usual generators.
The value of routine cytologic smears in pregnancy.

Abstract A report of 10,369 obstetric patients who had routine vaginal smears has been presented. One hundred and five patients had positive smears and, of these, 25 were found to have either invasive or in situ carcinoma of the cervix. In addition 19 cases showed basal cell hyperplasia. There seems to be enough carcinoma of the cervix in younger women, especially those bearing children, to warrant the routine use of vaginal smears in pregnancy. In addition to those patients found to have cervical malignancies there are also those with basal cell hyperplasia which should be watched carefully for a possible progression of this lesion to malignancy.
Price Cutting and Business Stealing in Imperfect Cartels

Although economists have made substantial progress toward formulating theories of collusion in industrial cartels that account for a variety of fact patterns, important puzzles remain. Standard models of repeated interaction formalize the observation that cartels keep participants in line through the threat of punishment, but they fail to explain two important factual observations: first, apparently deliberate cheating actually occurs; second, it frequently goes unpunished even when it is detected. We propose a theory of equilibrium price cutting and business stealing in cartels to bridge this gap between theory and observation.
Directional feature detection and correspondence

A method is proposed to detect useful directional feature points other than corner points considering that the number of corner points may not be sufficient in a scene. This is achieved by directional analysis of properties of image points by virtue of the proposed gradient operators with different direction topologies. A matching criterion is also proposed to find the initial correspondence by using the feature vectors that are acquired from the results of directional analysis. For the purpose of improving the final correspondence, four constraints are employed in the system to seek and refine the correspondence.
Threat of Dismissal: Incentive or Sorting?

Many people are fired from their jobs for poor performance. However, it is difficult to distinguish whether they are fired because they are not well suited for their job (sorting explanation) or because the firms are trying to provide incentives for effort (incentive explanation). This article develops a dynamic incentive model of dismissal and proposes a methodology to distinguish between these two explanations. The methodology is based on learning‐by‐doing and changes in the slope of dismissal probability with respect to tenure. Using personnel data from a large U.S. company, this study finds significant evidence for the incentive explanation.
INFORMATION BOTTLENECKS, CAUSAL STATES, AND STATISTICAL RELEVANCE BASES: HOW TO REPRESENT RELEVANT INFORMATION IN MEMORYLESS TRANSDUCTION

Discovering relevant, but possibly hidden, variables is a key step in constructing useful and predictive theories about the natural world. This brief note explains the connections between three approaches to this problem: the recently introduced information-bottleneck method, the computational mechanics approach to inferring optimal models, and Salmon's statistical relevance basis.
Different Strokes for Different Folks: The Impact of Sex Dissimilarity in the Empowerment–Performance Relationship

Organizations often utilize empowerment as a way to bolster performance. It is largely assumed, however, that its impact in this capacity is equivalent across organizational members. We tested this notion within a sample of 420 employees belonging to 75 teams in a Chinese organization and found that team empowerment related positively to supervisor-rated in-role and self-rated extra-role performance through its effect on individual psychological empowerment. More important, employee–coworker demographic dissimilarity moderated both stages of this indirect relationship. Specifically, when employee–coworker sex dissimilarity was higher, the following relationships were attenuated: (a) team empowerment–individual empowerment, (b) individual empowerment–in-role performance, and (c) individual empowerment–extra–role performance. Collectively, the results illustrate that the impact of empowerment is contingent upon demographic dissimilarity.
Does the Red Queen Reign in the Kingdom of Digital Organisms

I investigate the competition dynamics between two identical clones of digital organisms, for three sets of clones taken from different locations in the fitness landscape. When the clones are taken from the base of a fitness peak, such that beneficial mutations are abundant, then both gain in fitness during the competition (Red Queen effect), until eventually one clone drives the other to extinction. When beneficial mutations are rare or completely absent, on the other hand, then either the clone that finds a beneficial mutation first wins, or the clone that loses the highest-fitness mutant first loses the competition. The time until one of the two strains dies out is in general shorter in the Red Queen case than in the other cases. I discuss the relevance of my findings for competition studies with RNA viruses.
Socioeconomic impact of the crisis in north Mali on displaced people

This paper analyzes the impact of the 2012 crisis in Mali on internally displaced people, refugees and returnees. It uses information from a face-to-face household survey as well as follow-up interviews with its respondents via mobile phones. This combination was found to present a good and robust way to monitor the impact of conflict on hard-to-reach populations who at times live in areas inaccessible to enumerators. Results indicate that better educated and wealthier households as well as those exposed to less violence fled the crisis. Significant amounts of durable goods (20–60 percent) and animals (75–90 percent were lost and the welfare of the displaced declined considerably as a result of the crisis. Yet over time its impact has diminished. By February 2015, most eligible children were going to school and employment levels and number of meals consumed were at pre-crisis levels. The paper finds that different ethnic groups chose different places of refuge. Depending on location, the narrative of the crisis and the solutions that are envisaged differ diametrically.
The informative extremes: using both nearest and farthest individuals can improve relief algorithms in the domain of human genetics

A primary goal of human genetics is the discovery of genetic factors that influence individual susceptibility to common human diseases. This problem is difficult because common diseases are likely the result of joint failure of two or more interacting components instead of single component failures. Efficient algorithms that can detect interacting attributes are needed. The Relief family of machine learning algorithms, which use nearest neighbors to weight attributes, are a promising approach. Recently an improved Relief algorithm called Spatially Uniform ReliefF (SURF) has been developed that significantly increases the ability of these algorithms to detect interacting attributes. Here we introduce an algorithm called SURF* which uses distant instances along with the usual nearby ones to weight attributes. The weighting depends on whether the instances are are nearby or distant. We show this new algorithm significantly outperforms both ReliefF and SURF for genetic analysis in the presence of attribute interactions. We make SURF* freely available in the open source MDR software package. MDR is a cross-platform Java application which features a user friendly graphical interface.
Mass spectrometry for investigations of gas-phase radical cation chemistry : The two step cycloaddition of the benzene radical cation and 1,3-butadiene

Abstract Mass spectrometric techniques are now used extensively for the study of gas-phase radical cation chemistry. The generation and structural properties, the unimolecular and bimolecular chemistry of some representative radical cation systems, and the methods of study are reviewed. The structure of the ionmolecule adduct produced in the reaction of the benzene radical cation and neutral 1,3-butadiene was investigated by collisionally stabilizing the adduct and then acquiring its collision-activated decomposition spectrum. The CAD spectrum of the adduct changes dramatically as a function of the degree of collisional stabilization. This observation is interpreted in terms of two distinct structures for the adduct. The species that is stabilized at 0.7 Torr has a CAD spectrum similar to the 2-phenyl-2-butene radical cation. The second structure, stabilized at 0.1 Torr, has a CAD similar to that of 1-methylindan. The results of these experiments are interpreted in terms of a two-step cycloaddition mechanism for the formation of the 1-methylindan radical cation.
Modeling Firm Dynamics to Identify the Cost of Financing Constraints in Ghanaian Manufacturing

Economic development requires the growth of productive firms. However, financing constraints may limit firms? investment abilities. This paper estimates the cost of financing constraints to firms, for example in terms of idle investment opportunities, and their aggregate implications. To this end, I develop and estimate a dynamic model of firm-level investment. The model allows me to deal with the main identification problem faced by work that studies financing constraints, namely to identify the investment opportunities and the constraints of a firm separately. The model also allows for other potential explanations of the observed phenomenon, in particular adjustment costs and uncertainty. I solve the model using dynamic programming methods and estimate it via simulation methods, using firm level data from Ghana. Counterfactual analyses are then carried out to quantify the importance of financing constraints. These counterfactuals indicate that removing the constraints would imply economically significant increases in investment that are associated with higher levels of consumption.
The Case for a Standard Model with Anomalous U(1)

A gauged phase symmetry with its anomalies cancelled by a Green-Schwarz mechanism, broken at a large scale by an induced Fayet-Iliopoulos term, is a generic feature of a large class of superstring theories. It induces many desirable phenomenological features: Yukawa coupling hierarchy, the emergence of a small Cabibbo-like expansion parameter, relating the Weinberg angle to b−τ unification, and the linking of R-parity conservation to neutrino masses. Some are discussed in the context of a three-family model which reproduces all quark and lepton mass hierarchies as well as the solar and atmospheric neutrino oscillations.
A Strategic Theory of Inflation

A strategic mechanism of price adjustment is introduced to explain inflations in the U.S. during 1909-1974. The mechanism follows from our theory that when the profit rate is above a normal-target rate, competitive forces operate to lower prices while if the profit rate is below the target a correlated strategy among firms operates to generate a rise in prices as a strategy to improve profitability. The notion of "correlated strategy" is adopted from game theory. The mechanism may operate in harmony or against demand and the net effect is what we call the "basic inflation." Contrary to a-priori notions of positive association between inflation rates and profit rates, our theory proposes a critical test of a negative association between these variables. Such a relationship is in fact empirically established. The analysis shows that large and persistent inflationary pressures are generated by low profitability and during 1971-1977 those accounted for some 20%-50% of total inflation. These pressures would be present even if no increase in cost occurs. This suggests that an important cause of the 1970's inflation is the low profit rate in the private sector and any public policy against inflation will fail if it does not aim at the same time to raise the profit rate on private capital.
The complexity of quantum spin systems on a two-dimensional square lattice

The problem 2-LOCAL HAMILTONIAN has been shown to be complete for the quantumcomputational class QMA [1]. In this paper we show that this important problemremains QMA-complete when the interactions of the 2-local Hamiltonian are betweenqubits on a two-dimensional (2-D) square lattice. Our results are partially derived withnovel perturbation gadgets that employ mediator qubits which allow us to manipulatek-local interactions. As a side result, we obtain that quantum adiabatic computationusing 2-local interactions restricted to a 2-D square lattice is equivalent to the circuitmodel of quantum computation. Our perturbation method also shows how any stabilizerspace associated with a k-local stabilizer (for constant k) can be generated as anapproximate ground-space of a 2-local Hamiltonian.
Advertising Intensity and Welfare in an Equilibrium Search Model

I analyze an equilibrium search model in a duopoly setting with bilateral heterogeneities in production and search costs in which firms can advertise by announcing price. I compare the market advertising level to the socially optimal level, where I find that costly search can improve welfare and that firms may under- or over-advertise relative to the social optimum depending on the costs of search. The results suggest that, in markets with sufficiently low search costs, firms are likely over-advertising relative to the socially optimal level, and vice versa for markets with sufficiently high search costs.
Local Supermodularity and Unique Assortative Matching

We consider sufficient conditions for uniqueness in two-sided matching models with transfers. We analyse the strategy-proofness of allocation mechanism
Wackenroder y la concepción musical del primer romanticismo

Wackenroder and the musical conception of early Romanticism.- The early romantic movement brings in a new general conception of art and the artist. Within this context, music is treated as a proper and independent form of art. This paper shows how a reflection on music is to be found expressed in the texts of Wackenroder, which is later to be carried on by other thinkers.
Offshoring of American Jobs: What Response from U.S. Economic Policy?

Two leading economists discuss a range of issues relating to the "offshoring" of American jobs, from free trade to unemployment levels. It is no surprise that many fearful American workers see the call center operator in Bangalore or the factory worker in Guangzhou as a threat to their jobs. The emergence of China and India (along with other, smaller developing countries) as economic powers has doubled the supply of labor to the integrated world economy. Economic theory suggests that such a dramatic increase in the supply of labor without an accompanying increase in the supply of capital is likely to exert downward pressure on wages for workers already in the integrated world economy, and wages for most workers in the United States have indeed stagnated or declined. In this book, leading economists Jagdish Bhagwati and Alan S. Blinder offer their perspectives on how the outsourcing of labor and the shifting of jobs to lower-wage countries affect the U.S. economy and what, if any, policy responses are required. Bhagwati, in his colorful and pithy style, focuses on globalization and free trade, while Blinder, erudite and witty, addresses the significance of labor market adjustment caused by trade. Bhagwati's and Blinder's contributions are followed by comments from economists Richard Freedman, Douglas A. Irwin, Lori G. Kletzer, and Robert Z. Lawrence. Bhagwati and Blinder then respond separately to the issues raised. Benjamin Friedman, who edited this volume (and organized the symposium that inspired it), provides an introduction.
On the effect of air humidity on soil susceptibility to wind erosion: The case of air‐dry soils

[1] Wind erosion is a widespread process in drylands, and contributes to loss of soil fertility, alteration of atmospheric radiation, and air pollution. Erosion occurs when wind speed exceeds a certain threshold, which depends on a number of factors, including surface soil moisture. It is shown that in air-dry soils surface moisture and threshold wind speed depend significantly on air humidity. Thus, in arid regions variations in surface soil moisture can be significantly affected by changes in atmospheric humidity, with an important effect on wind erosion potential. Wind tunnel tests were conducted to investigate this dependence of threshold velocity on air humidity in air-dry soils. It was found that at these moisture levels, the threshold velocity decreases with an increase in air humidity. This result is explained by the effect of hygroscopic forces and by their dependence on soil matric potential in dry soils. INDEX TERMS: 1815 Hydrology: Erosion and sedimentation; 1866 Hydrology: Soil moisture; 1809 Hydrology: Desertification. Citation: Ravi, S., P. D’Odorico, T. M. Over, and T. M. Zobeck (2004), On the effect of air humidity on soil susceptibility to wind erosion: The case of air-dry soils, Geophys. Res. Lett., 31, L09501, doi:10.1029/2004GL019485.
A mathematical programming approach to the fractionation problem in chemoradiotherapy

In concurrent chemoradiotherapy, chemotherapeutic agents are administered during the course of radiotherapy to enhance the primary tumor control. However, this treatment often comes at the expense of increased risk of normal-tissue complications. The additional biological damage is mainly attributed to two mechanisms of action, which are the independent cytotoxic activity of chemotherapeutic agents and their interactive cooperation with radiation. The goal of this study is to develop a mathematical framework to obtain drug and radiation administration schedules that maximize the therapeutic gain for concurrent chemoradiotherapy. In particular, we analyze the impact of incorporating these two mechanisms into the radiation fractionation problem. Considering each mechanism individually, we first derive closed-form expressions for the optimal radiation fractionation regimen and the corresponding drug administration schedule. We next study the case in which both mechanisms are simultaneously present and develo...
Ising Field Theory in a Magnetic Field: Analytic Properties of the Free Energy

We study the analytic properties of the scaling function associated with the 2D Ising model free energy in the critical domain T→T c , H→0. The analysis is based on numerical data obtained through the Truncated Free Fermion Space Approach. We determine the discontinuities across the Yang–Lee and Langer branch cuts. We confirm the standard analyticity assumptions and propose “extended analyticity;” roughly speaking, the latter states that the Yang–Lee branching point is the nearest singularity under Langer's branch cut. We support the extended analyticity by evaluating numerically the associated “extended dispersion relation.”
Rational Inattention, Portfolio Choice, and the Equity Premium

This paper explores how the introduction of Rational Inattention (RI) affects optimal consumption and portfolio rules and asset pricing in the consumption-based CAPM framework. I first solve an otherwise standard portfolio choice and asset pricing model with RI explicitly and show that RI can generate smooth consumption process and low contemporaneous correlation between consumption growth and asset returns. Second, it is shown that in the RI economy asset returns are determined by the ultimate consumption risk rather than the contemporaneous risk. As a result, RI has a potential to reduce the demand for the risky asset and could endo- genize limited stock market participation hypothesis. Third, I show that RI can disentangle the coefficient of relative risk aversion with the elasticity of intertemporal substitution endoge- neously by increasing the effective CRRA. RI can therefore be an alternative explanation for the equity premium puzzle and the risk free rate puzzle. Fourth, I compare RI with recursive preference, robustness, and habit formation. Fifth, I investigate the implications of RI for optimal consumption and portfolio choice when investment opportunities are stochastic and labor income is modelled explicitly. Finally, I propose a general equilibrium asset pricing framework to examine the implications of RI for the equity premium, the mean ratio of price to dividend, and the equity volatility in equilibrium.
Health care professionals and adolescent vaccination. A call for intervention research.

In their recently published research study, Gargano et al. found that a physician's recommendation and parental health beliefs had significant effects on adolescent vaccination rates and on parental intentions to vaccinate. This research replicates the findings of a number of human papillomavirus (HPV) vaccine-focused research studies, but explores new territory by focusing on all recommended adolescent vaccines: meningococcal-conjugate (MCV4), HPV, influenza, and tetanus, diphtheria, and acellular pertussis (Tdap) vaccines. Although Gargano et al.'s study is relatively small in scale and focuses on only one county in Georgia, their results are consistent with many other research reports, suggesting that their findings are robust and replicable. Most published intervention studies have targeted parents and young adults, with little focus on health care professionals. However, given the centrality of physician recommendation in adolescent vaccination, as shown by Gargano et al., it is clear that the time h...
Embedded Clusters and the IMF

Despite valiant efforts over nearly five decades, attempts to determine the IMF over a complete mass range for galactic field stars and in open clusters have proved difficult. Infrared imaging observations of extremely young embedded clusters coupled with Monte Carlo modeling of their luminosity functions are improving this situation and providing important new contributions to our fundamental knowledge of the IMF and its universality in both space and time.
Back to the Future: Postwar Reconstruction and Stabilization in Lebanon

Following the 15-year civil war that started in 1975, Lebanon's government began the difficult task of economic stabilization and confidence building, on the one hand, and postwar reconstruction and development, on the other. The government led the reconstruction effort by formulating programs that aimed to rapidly rehabilitate the country's severly damaged infrastructure in preparation for private-sector-led growth over the medium term. At the same time, Lebanon introduced an exchange-rate-based nominal anchor policy to stabilize expectations and cut inflation. This paper analyzes the government's progress with the policies adopted.
Masers in the Sky

The existence of astronomical masers (which operate on the same principles as lasers, except that they involve microwave radiation instead of visible light) was first postulated in the 1960s to explain some of the highly unusual emission properties of interstellar OH (the hydroxyl radical). Maser emission has now been detected from many different molecules in different astronomical environments, but direct evidence for maser amplification has been hard to come by. In his Perspective, Elitzur highlights the report by Weisberg et al., who provide direct evidence for an interstellar amplifier in the direction of the pulsar B1641-45. Thanks to masers, radio astronomy has achieved extremely higher resolution, but similar data are required at other wavelengths to obtain a full understanding of astronomical sources.
Collisions and Mergers of Disk Galaxies: Hydrodynamics of Star Forming Gas

We summarize the results of numerical simulations of colliding gas-rich disk galaxies in which the impact velocity is set parallel to the spin axes of the two galaxies. The effects of varying the impact speed are studied with particular attention to the resulting gaseous structures and shockwave patterns, and the time needed to produce these structures. The simulations employ an N-body treatment of the stars and dark matter, together with an SPH treatment of the gas, in which all components of the models are gravitationally active. The results indicate that for such impact geometries, collisions can lead to the very rapid formation of a central, rapidly rotating, dense gas disk, and that in all cases extensive star formation is predicted by the very high gas densities and prevalence of shocks, both in the nucleus and out in the galactic disks. As the dense nucleus is forming, gas and stars are dispersed over very large volumes, and only fall back towards the nucleus over long times. In the case of low impact velocities, this takes an order of magnitude more time than that needed for the formation of a dense nucleus.
A Measure of the Goodness of Fit in Unbinned Likelihood Fits

Maximum likelihood fits to data can be done using binned data (histograms) and unbinned data. With binned data, one gets not only the fitted parameters but also a measure of the goodness of fit. With unbinned data, currently, the fitted parameters are obtained but no measure of goodness of fit is available. This remains, to date, an unsolved problem in statistics. Using Bayes theorem and likelihood ratios, we provide a method by which both the fitted quantities and a measure of the goodness of fit are obtained for unbinned likelihood fits, as well as errors in the fitted quantities. We provide an ansatz for determining Bayesian a priori probabilities.
The dynamics of product innovation and firm competences

This study examines how product innovation contributes to the renewal of the firm through its dynamic and reciprocal relation with the firm's competences. Field research in five high-tech firms of varying age, size, and level of diversification is combined with analysis of existing theory to develop the findings of the study. Based on the notion that new products are created by linking competences relating to technologies and customers, a typology is derived that classifies new product projects based on whether a new product can draw on existing competences, or whether it requires competences the firm does not yet have. Following organizational learning theory, these options are conceptualized as exploitation and exploration. These organizational learning concepts are used to gain a dynamic and path-dependent view of product innovation and firm development, and to reveal the unique nature and challenges of different types of product innovation. Copyright © 2002 John Wiley & Sons, Ltd.
Evaluation of several polymer films for use as electrical insulators

A facility was developed in which polymer samples were aged to 32,700 h with an applied load of 6.9 MPa and at temperatures of 70, 110, 135, and 160°C. The aging environment was 0.4 MPa (4 atm) SF 6 containing either 4 or 40 Pa (40 or 400 µatm) H 2 O. The polymers evaluated to 32,700 h were polyethylene terephthalate, polycarbonate, polyparabanic acid, polyethersulfone, and polyimide. Polysulfone and polyetherimide were aged to 11,200 h. Only polyethylene terephthalate showed any interaction with the environment, and this was in the form of higher moisture causing greater reductions in fracture strain. Electrical breakdown measurements were made on most of the aged samples, and there were no reductions in breakdown voltage as a result of aging. The sticking temperatures between polymers was determined to be 160°C for polyethylene terephthalate; 110°C for polycarbonate; 160°C for polysulfone; and >160°C for polyetherimide, polyethersulfone, polyparabanic acid, and polyimide.
Explicit rank-metric codes list-decodable with optimal redundancy

We construct an explicit family of linear rank-metric codes over any field Fh that enables efficient list decoding up to a fraction ρ of errors in the rank metric with a rate of 1− ρ− e, for any desired ρ ∈ (0, 1) and e > 0. Previously, a Monte Carlo construction of such codes was known, but this is in fact the first explicit construction of positive rate rank-metric codes for list decoding beyond the unique decoding radius. Our codes are explicit subcodes of the well-known Gabidulin codes, which encode linearized polynomials of low degree via their values at a collection of linearly independent points. The subcode is picked by restricting the message polynomials to an Fh-subspace that evades the structured subspaces over an extension field Fht that arise in the linear-algebraic list decoder for Gabidulin codes due to Guruswami and Xing (STOC’13). This subspace is obtained by combining subspace designs contructed by Guruswami and Kopparty (FOCS’13) with subspace-evasive varieties due to Dvir and Lovett (STOC’12). We establish a similar result for subspace codes, which are a collection of subspaces, every pair of which have low-dimensional intersection, and which have received much attention recently in the context of network coding. We also give explicit subcodes of folded ReedSolomon (RS) codes with small folding order that are list-decodable (in the Hamming metric) with optimal redundancy, motivated by the fact that list decoding RS codes reduces to list decoding such folded RS codes. However, as we only list decode a subcode of these codes, the Johnson radius continues to be the best known error fraction for list decoding RS codes. ∗Research supported in part by NSF CCF-0963975. †guruswami@cmu.edu ‡wangc@cs.cmu.edu ISSN 1433-8092 Electronic Colloquium on Computational Complexity, Report No. 170 (2013)
Uplink performance of large optimum-combining antenna arrays in power-controlled cellular networks

The uplink of interference-limited cellular networks with base stations that have large numbers of antennas and use linear Minimum-Mean-Square Error (MMSE) processing with power control is analyzed. Simple approximations, which are exact in an asymptotic sense, are provided for the spectral efficiencies (b/s/Hz) of links in these systems. It is also found that when the number of base-station antennas is moderately large, and the number of mobiles in the entire network is large, correlations between the transmit powers of mobiles within a given cell do not significantly influence the spectral efficiency of the system. As a result, mobiles can perform simple power control (e.g. fractional power control) that does not depend on other users in the network, reducing system complexity and improving the analytical tractability of such systems.
On Longest Repeat Queries Using GPU

Repeat finding in strings has important applications in subfields such as computational biology. The challenge of finding the longest repeats covering particular string positions was recently proposed and solved by Ileri et al., using a total of the optimal O(n) time and space, where n is the string size. However, their solution can only find the leftmost longest repeat for each of the n string position. It is also not known how to parallelize their solution. In this paper, we propose a new solution for longest repeat finding, which although is theoretically suboptimal in time but is conceptually simpler and works faster and uses less memory space in practice than the optimal solution. Further, our solution can find all longest repeats of every string position, while still maintaining a faster processing speed and less memory space usage. Moreover, our solution is parallelizable in the shared memory architecture (SMA), enabling it to take advantage of the modern multi-processor computing platforms such as the general-purpose graphics processing units (GPU). We have implemented both the sequential and parallel versions of our solution. Experiments with both biological and non-biological data show that our sequential and parallel solutions are faster than the optimal solution by a factor of 2–3.5 and 6–14, respectively, and use less memory space.
Dynamical tides in compact white dwarf binaries: tidal synchronization and dissipation

In compact white dwarf (WD) binary systems (with periods ranging from minutes to hours), dynamical tides involving the excitation and dissipation of gravity waves play a dominant role in determining the physical conditions (such as rotation rate and temperature) of the WDs prior to mass transfer or binary merger. We calculate the amplitude of the tidally excited gravity waves as a function of the tidal forcing frequency ω= 2(Ω−Ωs) (where Ω is the orbital frequency and Ωs is the spin frequency) for several realistic carbon–oxygen WD models, under the assumption that the outgoing propagating waves are efficiently dissipated in the outer layer of the star by non-linear effects or radiative damping. Unlike main-sequence stars with distinct radiative and convection zones, the mechanism of wave excitation in WDs is more complex due to the sharp features associated with composition changes inside the WD. In our WD models, the gravity waves are launched just below the helium–carbon boundary and propagate outwards. We find that the tidal torque on the WD and the related tidal energy transfer rate, , depend on ω in an erratic way, with varying by orders of magnitude over small frequency ranges. On average, scales approximately as Ω5ω5 for a large range of tidal frequencies. We also study the effects of dynamical tides on the long-term evolution of WD binaries prior to mass transfer or merger. Above a critical orbital frequency Ωc, corresponding to an orbital period of the order of 1h (depending on WD models), dynamical tides efficiently drive Ωs towards Ω, although a small, almost constant degree of synchronization (Ω−Ωs∼ constant) is maintained even at the smallest binary periods. While the orbital decay is always dominated by gravitational radiation, the tidal energy transfer can induce a significant phase error in the low-frequency gravitational waveforms, detectable by the planned Laser Interferometer Space Antenna project. Tidal dissipation may also lead to significant heating of the WD envelope and brightening of the system long before binary merger.
Effects of ciprofloxacin-containing antimicrobial scaffolds on dental pulp stem cell viability-In vitro studies.

Abstract Objective A combination of antibiotics, including but not limited to metronidazole (MET) and ciprofloxacin (CIP), has been indicated to eradicate bacteria in necrotic immature permanent teeth prior to regenerative procedures. It has been shown clinically that antibiotic pastes may lead to substantial stem cell death. The aim of this study was to synthesise scaffolds containing various concentrations of CIP to enhance cell viability while preserving antimicrobial properties . Design Polydioxanone (PDS)-based electrospun scaffolds were processed with decreasing CIP concentrations (25–1 wt.%) and morphologically evaluated using scanning electron microscopy (SEM). Cytotoxicity assays were performed to determine whether the amount of CIP released from the scaffolds would lead to human dental pulp stem cell (hDPSC) toxicity. Similarly, WST-1 assays were performed to evaluate the impact of CIP release on hDPSC proliferation. Pure PDS scaffolds and saturated double antibiotic solution MET/CIP (DAP) served as both positive and negative controls, respectively. Antibacterial efficacy against E. faecalis ( Ef ) was tested. Results A significant decrease in hDPSC’ viability at concentrations 5–25 wt.% was observed. However, concentrations below 5 wt.% did not impair cell viability. Data from the WST-1 assays indicated no detrimental impact on cell proliferation for scaffolds containing 2.5 wt.% CIP or less. Significant antimicrobial properties were seen for CIP-scaffolds at lower concentrations ( i.e. , 1 and 2.5 wt.%). Conclusion The obtained data demonstrated that a reduced concentration of CIP incorporated into PDS-based scaffolds maintains its antimicrobial properties while enhancing viability and proliferation of dental pulp stem cells.
A Morphological and Multicolor Survey for Faint QSOs in the Groth-Westphal Strip

Quasars that are representative of the populous faint end of the luminosity function are frustratingly dim, with m ~ 24 at intermediate redshift; moreover, ground-based surveys for such faint QSOs suffer substantial morphological contamination by compact galaxies with similar colors. In order to establish a more reliable ultrafaint QSO sample, we used the Apache Point Observatory 3.5 m telescope to take deep ground-based U-band CCD images in fields previously imaged in V and I with the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST). Our approach hence combines multicolor photometry with the 01 spatial resolution of HST to establish a morphological and multicolor survey for QSOs extending about 2 mag fainter than most extant ground-based surveys. We present results for the "Groth-Westphal strip," in which we identify 10 high-likelihood UV-excess candidates having stellar or stellar-nucleus + galaxy morphology in WFPC2. For m606 < 24.0 (roughly B 24.5), the surface density of such QSO candidates is 420 deg-2, or a surface density of 290 deg-2 with an additional V-I cut that may further exclude compact emission-line galaxies. Even pending confirming spectroscopy, the observed surface density of QSO candidates is already low enough to yield interesting comparisons: our measures agree extremely well with the predictions of several recent luminosity function models.
Long Story Short

Long Story Short is a composite group interview that takes form variously as a film, an installation, and an online interactive web documentary drawn from and linked to an archive of video diaries made by 75 interviewees who reflect on poverty in America – causes, challenges, misperceptions, and solutions. Multiple frames of videos sit side by side – creating a new form of social cinema. Voices are woven together to align and intersect, suggesting that for every speaker there could be numerous others, and that many of poverty’s narratives are fundamentally shared, as are the psychological states it can produce. Video diaries were made using webcams and laptops – the tools of amateur online video and some of the same technologies – high tech and digital – that ushered in hardships for low-skilled workers and their families in the first place, leading to a shrinking demand and lower wages for unskilled labor. The video diaries – inserted within the vernacular of social media – bare the markings of that genre: its direct address, intimacy, informality, and faces illuminated by the screen. The potential to travel across digital networks and platforms is written on their surface. While one of the potentially productive effects of networked culture has been a shift away from a focus on one voice to many, it has also produced a class of overvisible and a class of unseen – those whose data is not worth much. Long Story Short creates a missing archive, jarring expectations and making visible the limits of who we typically find speaking to us on our screens. It responds to our current moment of increasing and dramatic economic inequality, and explores how depictions of poverty might benefit from, as well as reflect on, current modes of digital and image mobility, dissemination, and display. It explores lives mostly not seen, and not often represented in public, especially not in digital form, and not on our screens. It proposes a more social media.
Synthesis of disubstituted dithioethers: tert-butoxide promoted elimination/ring opening of 1,3-dithianes followed by palladium-catalyzed C-S bond formation.

We report the tandem base-promoted elimination/ring-opening of 2-benzyl-1,3-dithianes with subsequent cross coupling of the pendent thiol with a range of aryl bromides. A simple Pd(OAc)2/Xantphos catalyst system affects this new reaction and is compatible with a wide range of functional groups, including heteroaromatic coupling partners. The transformation proceeds in good to excellent yields (69–99%) and exhibits strong stereoselectivity, forming the E-alkene as the major diastereomer. This new methodology provides access to nonsymmetric propylene styryl/aryl dithioethers, a previously undisclosed motif.
Do services and transfers reach Morocco's poor? Evidence from poverty and spending maps

In the absence of household level data on participation in public programs, spending allocations and poverty measures across regions of Morocco are used to infer incidence across poor and non-poor groups and to decompose incidence within rural and urban areas separately, as well as to decompose improvements in enrolment rates across poor and non-poor children by gender. Programs appear to be well targeted to the rural poor but not to the urban poor. Substantial benefits accrue to the urban non-poor, while benefits largely bypass the urban poor. The analysis also uncovers evidence of impressive progress in primary and secondary school enrolments for the poor as well as for poor girls since 1994. However, here too, the gains are concentrated on the rural poor.
Electrophoresis of Proteins and Nucleic Acids

Electrophoresis forms the basis of routine separation and analysis of nucleic acid and protein molecules. It is difficult to scan the biological literature without some form of electrophoresis being used in the methods and results for critical preparation and analysis. The applications of nucleic acid electrophoresis include purification, genetic analysis, DNA probe preparation, and DNA and RNA sequence determination. Protein electrophoresis is used for purification, size estimation, subunit composition, protein expression, and identification of posttranslational modifications, in addition to forming the basis for the first step in immunoblotting. While the analysis of proteins and nucleic acids is described in detail, the future applications of microelectrophoresis and microfluidics are also discussed. The bibliography contains both historically significant references and current references outlining established protocols, providing the bench user a guide to the use of electrophoretic techniques in their research. Keywords: proteomics; genomics; electrophoresis; separations; protein; DNA; RNA; SDS PAGE; sequencing; blotting
Hardness of finding independent sets in 2-colorable and almost 2-colorable hypergraphs

This work studies the hardness of finding independent sets in hypergraphs which are either 2-colorable or are almost 2-colorable, i.e. can be 2-colored after removing a small fraction of vertices and the incident hyperedges. To be precise, say that a hypergraph is (1 -- e)-almost 2-colorable if removing an e fraction of its vertices and all hyperedges incident on them makes the remaining hypergraph 2-colorable. In particular we prove the following results.• For an arbitrarily small constant γ > 0, there is a constant ξ > 0, such that, given a 4-uniform hypergraph on n vertices which is (1 -- e)-almost 2-colorable for e = 2-(logn)ξ, it is quasi-NP-hard1 to find an independent set of n/(2(logn)1-γ) vertices.• For any constants e, δ > 0, given as input a 3-uniform hypergraph on n vertices which is (1 -- e)-almost 2-colorable, it is NP-hard to find an independent set of δn vertices.• Assuming the d-to-1 Games Conjecture the following holds. For any constant δ > 0, given a 2-colorable 3-uniform hypergraph on n vertices, it is NP-hard to find an independent set of δn vertices.The hardness result on independent set in almost 2-colorable 3-uniform hypergraphs was earlier known only assuming the Unique Games Conjecture. In this work we prove the result unconditionally, combining Fourier analytic techniques with the Multi-Layered PCP of [11].For independent sets in 2-colorable 3-uniform hypergaphs we prove the first strong hardness result, albeit assuming the d-to-1 Games Conjecture. Our reduction uses the d-to-1 Game as a starting point to construct a Multi-Layered PCP with the smoothness property. We use analytical techniques based on the Invariance Principle of Mossel [36]. The smoothness property is crucially exploited in a manner similar to recent work of Hastad [20] and Wenner [45].Our result on almost 2-colorable 4-uniform hypergraphs gives the first nearly polynomial hardness factor for independent set in hypergraphs which are (almost) colorable with constantly many colors. It partially bridges the gap between the previous best lower bound of poly(log n) and the algorithmic upper bounds of nΩ(1). This also exhibits a bottleneck to improving the algorithmic techniques for hypergraph coloring.
Accelerated cycle life performance for ovonic nickel-metal hydride cells

Ovonic Battery Company and Rockwell International have cooperated on the evaluation testing of ovonic 3.5 A-h nickel-metal hydride cells for aerospace application. Performance and cycle life data for a 6 cell battery collected during 3,000 cycles of an accelerated cycle life test at 30% DoD and 25/spl deg/c are presented.
Assessing Real Exchange Rate Misalignments

There is a renewed debate on the role of exchange rate policies as an industrial policy tool in both academic and policy circles. Policy practitioners usually examine real exchange rate misalignments to monitor the behavior of this key relative price and, if possible, exploit distortions in the traded and non-traded relative price to promote growth. Anecdotal evidence shows that some countries have pursued very active exchange rate policies to promote the export sector and enhance growth by undervaluing their currencies. The main goal of this paper is to provide a systematic characterization of real exchange rate undervaluations. The long-run real exchange rate equation is estimated using: (a) Johansen time series cointegration estimates, and (b) pooled mean group estimates for non-stationary panel data. The paper constructs a dataset of real undervaluation episodes. It first evaluates whether (and if so, to what extent) economic policies can be used to either cause or sustain real undervaluations. In this context the paper empirically models the likelihood and magnitude of sustaining real exchange rate undervaluations by examining their link to policy instruments (such as exchange rate regimes and capital controls, among other policies) using probit and Tobit models. Finally, it investigates whether foreign exchange intervention can generate persistent real exchange rate deviations from equilibrium. In general, it finds that intervention can lead to greater persistence in the incidence and magnitude of real exchange rate undervaluations.