cssi/SciSciGPT-SciSciNet huggingface dataset:
Dark Matter in Supergravity

We consider neutralino-proton cross sections for halo dark matter neutralinos \( \left( {\tilde{\chi }_{1}^{0}} \right) \) within the framework of supergravity models with R-parity invariance for models with universal soft breaking (mSUGRA) and models with nonuniversal soft breaking. The analysis includes the necessary corrections to treat the large tanβ region (i.e. L-R mixing in the squark and slepton mass matrices, loop corrections to the b and τ masses,etc) and includes all coannihilation phenomena. For mSUGRA, dark matter detectors with current sensitivity are seen to be probing the region where tanβ ≳25, \( {{\Omega }_{{\tilde{\chi }_{1}^{0}}}}{{h}^{2}} < 0.1,{{m}_{{\tilde{\chi }_{1}^{0}}}} \lesssim 90GeV \), and for the light Higgs, m h ≲ 120 GeV. Nonuniversal models can have a much larger cross section, and current detectors can probe part of the parameter space where tans ≳ 4. Minimum cross sections are generally greater than 10–9 pb to 10–10 pb for m 1/2 = 600 GeV, (and hence accessible to planned future detectors), with the exception of a region when µ < 0 where for m 1/2 ≳ 450 GeV, 4 ≲ tanβ ≲ 20, the cross section drops to a minimum of about 1 × 10–12 pb at m 1/2 = 600 GeV, tanβ ⋍ 10. In this region, the gluino and squarks lie above 1 TeV, but should still be accessible to the LHC.
High-Tc Ferromagnetism and Electron Transport in p-Type Fe1–xSnxSb2Se4 Semiconductors

Single-phase polycrystalline powders of Fe1–xSnxSb2Se4 (x = 0 and 0.13) were synthesized by a solid-state reaction of the elements at 773 K. X-ray diffraction on Fe0.87Sn0.13Sb2Se4 single-crystal and powder samples indicates that the compound is isostructural to FeSb2Se4 in the temperature range from 80 to 500 K, crystallizing in the monoclinic space group C2/m (No. 12). Electron-transport data reveal a marginal alteration in the resistivity, whereas the thermopower drops by ∼60%. This suggests a decrease in the activation energy upon isoelectronic substitution of 13% Fe by Sn. Magnetic susceptibility and magnetization measurements from 2 to 500 K reveal that the Fe1–xSb2SnxSe4 phases exhibit ferromagnetic behavior up to ∼450 K (x = 0) and 325 K (x = 0.13). Magnetotransport data for FeSb2Se4 reveal large negative magnetoresistance, suggesting spin polarization of free carriers in the sample. The high-Tc ferromagnetism in Fe1–xSnxSb2Se4 phases and the decrease in Tc of the Fe0.87Sn0.13Sb2Se4 sample are rat...
As the market churns : estimates of firm exit and job loss using the World Bank's enterprise surveys

This paper uses a unique data set of panel firms from the World Bank's Enterprise Surveys in 47 economies, to provide estimates of the patterns of firm exit, and analyzes various firm characteristics and conditions under which firms leave the market. Firms' labor productivity and age are robustly associated with a lower likelihood of exit, consistent with conceptions of creative destruction and findings elsewhere in the literature. These findings are robust across several specifications. However, the effects are mitigated by other factors, such as use of bank financing and the presence of limited liability. Although firm size does appear to matter, its effect is lessened after accounting for labor productivity. The paper also provides basic estimates of job loss attributable to firm exit, estimating that on average 3 to 4 percent of private sector employment is lost per annum due to firm exit. Because of the challenges of data collection, the analysis relies on a necessarily conservative definition of exit and provides a framework for future work on utilizing such periodic survey panels to estimate the relative patterns of firm attrition and the associated job loss.
The productivity argument for investing in young children.

This paper presents a productivity argument for investing in disadvantaged young children. For such investment, there is no equity-efficiency tradeoff.(This abstract was borrowed from another version of this item.)
Optimal Redundancy Allocation for Disaster Recovery Planning in the Network Economy

In the present network economy, businesses are becoming increasingly reliant on information technology (IT) to perform their operations and exchange information with business partners. This heavy dependence on IT, however, poses a potential threat for an organization. When disasters strike and cause malfunction to its computing and communicating systems, it would be vulnerable to business discontinuity. As a result, the issue of how to strengthen IT capabilities so that a company can prevent or quickly recover from disasters becomes a serious concern. In this paper, a discrete optimization model is proposed to allocate redundancy to IT assets for disaster recovery planning. The objective is to maximize the overall survivability of an organization’s critical IT functions by selecting their appropriate redundancy levels while still satisfying a budgetary resource constraint. A solution procedure based on probabilistic dynamic programming is proposed to solve the problem, and an example is used to illustrate its usage and effectiveness.
Experimental demonstration of a semi-brittle origin for crustal strain transients

Plate tectonic motions cause faults to slip during earthquakes and through creep. Laboratory shear experiments on semi-brittle rock-analogue materials suggest that such slip could occur via growth of a series of fractures.
Efficient inference in persistent Dynamic Bayesian Networks

Numerous temporal inference tasks such as fault monitoring and anomaly detection exhibit a persistence property: for example, if something breaks, it stays broken until an intervention. When modeled as a Dynamic Bayesian Network, persistence adds dependencies between adjacent time slices, often making exact inference over time intractable using standard inference algorithms. However, we show that persistence implies a regular structure that can be exploited for efficient inference. We present three successively more general classes of models: persistent causal chains (PCCs), persistent causal trees (PCTs) and persistent polytrees (PPTs), and the corresponding exact inference algorithms that exploit persistence. We show that analytic asymptotic bounds for our algorithms compare favorably to junction tree inference; and we demonstrate empirically that we can perform exact smoothing on the order of 100 times faster than the approximate Boyen-Koller method on randomly generated instances of persistent tree models. We also show how to handle non-persistent variables and how persistence can be exploited effectively for approximate filtering.
Improved Information Gain Estimates for Decision Tree Induction

Ensembles of classification and regression trees remain popular machine learning methods because they define flexible non-parametric models that predict well and are computationally efficient both during training and testing. During induction of decision trees one aims to find predicates that are maximally informative about the prediction target. To select good predicates most approaches estimate an information-theoretic scoring function, the information gain, both for classification and regression problems. We point out that the common estimation procedures are biased and show that by replacing them with improved estimators of the discrete and the differential entropy we can obtain better decision trees. In effect our modifications yield improved predictive performance and are simple to implement in any decision tree code.
Characterizing internet worm infection structure

Internet worm infection continues to be one of top security threats and has been widely used by botnets to recruit new bots. In this work, we attempt to quantify the infection ability of individual hosts and reveal the key characteristics of the underlying topology formed by worm infection, i.e., the number of children and the generation of the worm infection family tree. Specifically, we apply probabilistic modeling methods and a sequential growth model to analyze the infection tree of a wide class of worms. Through both mathematical analysis and simulation, we find that the number of children has asymptotically a geometric distribution with parameter 0.5. As a result, on average half of infected hosts never compromise any vulnerable host, over 98% of infected hosts have no more than five children, and a small portion of infected hosts have a large number of children. We also discover that the generation follows closely a Poisson distribution and the average path length of the worm infection family tree increases approximately logarithmically with the total number of infected hosts.
Volatility Risks and Growth Options

We propose to measure growth opportunities by firms’ exposure to idiosyncratic volatility news. Theoretically, we show that the value of a growth option increases in idiosyncratic volatility but its response to volatility of aggregate shocks can be either positive or negative depending on option moneyness. Empirically, we show that price sensitivity to variation in idiosyncratic volatility carries significant information about firms’ future investment and growth even after controlling for conventional proxies of growth options such as book-to-market and other relevant firm characteristics. Consistent with our theoretical arguments, we also find that firm’ exposure to aggregate volatility, while priced, does not help predict their future growth. Option-intensive firms identified using our idiosyncratic volatility-based measure earn a lower premium than do firms that rely more heavily on assets in place.
Voltage-driven spin-transfer torque in a magnetic particle

We discuss a spin-transfer torque device, where the role of the soft ferromagnetic layer is played by a magnetic particle or a magnetic molecule, in weak tunnel contact with two spin polarized leads. We investigate if the magnetization of the particle can be manipulated electronically, in the regime where the critical current for magnetization switching is negligibly weak, which could be due to the reduced particle dimensions. Using master equation simulations to evaluate the effects of spin-orbit anisotropy energy fluctuations on spin-transfer, we obtain reliable reading and writing of the magnetization state of such magnetic particle, and find that the device relies on a critical voltage rather than a critical current. The critical voltage is governed by the spin-orbit energy shifts of discrete levels in the particle. This finding opens a possibility to significantly reduce the power dissipation involved in spin-transfer torque switching, by using very small magnetic particles or molecules.
Gallium Analogue of Soluble Prussian Blue KGa[Fe(CN)6]·nH2O: Synthesis, Characterization, and Potential Biomedical Applications

The gallium analogue of the soluble Prussian blue with the formula KGa[Fe(CN)6]·nH2O is synthesized and structurally characterized. A simple aqueous synthetic procedure for preparing nanoparticles of this novel coordination polymer is reported. The stability, in vitro ion exchange with ferrous ions, cytotoxicity, and cellular uptake of such nanoparticles coated with poly(vinylpyrrolidone) are investigated for potential applications of delivering Ga3+ ions into cells or removing iron from cells.
Leveraging history for faster sampling of online social networks

With a vast amount of data available on online social networks, how to enable efficient analytics over such data has been an increasingly important research problem. Given the sheer size of such social networks, many existing studies resort to sampling techniques that draw random nodes from an online social network through its restrictive web/API interface. While these studies differ widely in analytics tasks supported and algorithmic design, almost all of them use the exact same underlying technique of random walk - a Markov Chain Monte Carlo based method which iteratively transits from one node to its random neighbor.Random walk fits naturally with this problem because, for most online social networks, the only query we can issue through the interface is to retrieve the neighbors of a given node (i.e., no access to the full graph topology). A problem with random walks, however, is the "burn-in" period which requires a large number of transitions/queries before the sampling distribution converges to a stationary value that enables the drawing of samples in a statistically valid manner.In this paper, we consider a novel problem of speeding up the fundamental design of random walks (i.e., reducing the number of queries it requires) without changing the stationary distribution it achieves - thereby enabling a more efficient "drop-in" replacement for existing sampling-based analytics techniques over online social networks. Technically, our main idea is to leverage the history of random walks to construct a higher-ordered Markov chain. We develop two algorithms, Circulated Neighbors and Groupby Neighbors Random Walk (CNRW and GNRW) and rigidly prove that, no matter what the social network topology is, CNRW and GNRW offer better efficiency than baseline random walks while achieving the same stationary distribution. We demonstrate through extensive experiments on real-world social networks and synthetic graphs the superiority of our techniques over the existing ones.
How to grow a healthy merger tree

We investigate seven Monte Carlo algorithms - four old and three new - for constructing merger histories of dark matter haloes, using the extended Press-Schechter (EPS) formalism based on both the spherical and ellipsoidal collapse models. We compare, side-by-side, the algorithms' abilities at reproducing the analytic EPS conditional (or progenitor) mass function over a broad range of mass and redshift (z = 0 to 15). Among the four old algorithms (those by Lacey & Cole, Kauffmann & White, Somerville & Kolatt and Cole et al.), we find that only the method of Kauffmann & White produces a progenitor mass function that is consistent with the EPS prediction for all look-back redshifts. The origins of the discrepancies in the other three algorithms are discussed. Our three new algorithms are designed to generate the correct progenitor mass function at each time-step. We show that this is a necessary and sufficient condition for consistency with EPS at any look-back time. We illustrate the differences between the three new algorithms and the method of Kauffmann & White one by investigating two other conditional statistics: the mass function of the i th most massive progenitors and the mass function for descendants with N p progenitors.
Developing the chemistry of monovalent phosphorus.

Electrophilic terminal phosphinidene complexes can be seen as singlet phosphinidenes stabilized by complexation with electron withdrawing metallic centers. They allow the development of an original P(I) chemistry whose latest results are summarized. These include the description of the first stable electrophilic terminal phosphinidene complexes, new precursors for the widely used transient [RP–M(CO)5] complexes (M = Cr, Mo, W), new substituents at phosphorus, new reactions and new decomplexation techniques. Finally, a different approach is proposed for stabilizing singlet phosphinidenes by formation of adducts with nitrogen bases such as N-methylimidazole. The resulting zwitterions are potentially equivalent to singlet nucleophilic phosphinidenes. Their synthetic potential remains to be explored.
Joint source-channel coding with feedback

This paper quantifies the fundamental limits of variable-length transmission of a general (possibly analog) source over a memoryless channel with noiseless feedback, under a distortion constraint. We consider excess distortion, average distortion and guaranteed distortion (d-semifaithful codes). In contrast to the asymptotic fundamental limit, a general conclusion is that allowing variable-length codes and feedback leads to a sizable improvement in the fundamental delay-distortion tradeoff.
Proteomic profiling of halloysite clay nanotube exposure in intestinal cell co-culture

Halloysite is aluminosilicate clay with a hollow tubular structure with nanoscale internal and external diameters. Assessment of halloysite biocompatibility has gained importance in view of its potential application in oral drug delivery. To investigate the effect of halloysite nanotubes on an in vitro model of the large intestine, Caco-2/HT29-MTX cells in monolayer co-culture were exposed to nanotubes for toxicity tests and proteomic analysis. Results indicate that halloysite exhibits a high degree of biocompatibility characterized by an absence of cytotoxicity, in spite of elevated pro-inflammatory cytokine release. Exposure-specific changes in expression were observed among 4081 proteins analyzed. Bioinformatic analysis of differentially expressed protein profiles suggest that halloysite stimulates processes related to cell growth and proliferation, subtle responses to cell infection, irritation and injury, enhanced antioxidant capability, and an overall adaptive response to exposure. These potentially relevant functional effects warrant further investigation in in vivo models and suggest that chronic or bolus occupational exposure to halloysite nanotubes may have unintended outcomes.
The temporal logic of causal structures

Computational analysis of time-course data with an underlying causal structure is needed in a variety of domains, including neural spike trains, stock price movements, and gene expression levels. However, it can be challenging to determine from just the numerical time course data alone what is coordinating the visible processes, to separate the underlying prima facie causes into genuine and spurious causes and to do so with a feasible computational complexity. For this purpose, we have been developing a novel algorithm based on a framework that combines notions of causality in philosophy with algorithmic approaches built on model checking and statistical techniques for multiple hypotheses testing. The causal relationships are described in terms of temporal logic formulae, reframing the inference problem in terms of model checking. The logic used, PCTL, allows description of both the time between cause and effect and the probability of this relationship being observed. We show that equipped with these causal formulae with their associated probabilities we may compute the average impact a cause makes to its effect and then discover statistically significant causes through the concepts of multiple hypothesis testing (treating each causal relationship as a hypothesis), and false discovery control. By exploring a well-chosen family of potentially all significant hypotheses with reasonably minimal description length, it is possible to tame the algorithm's computational complexity while exploring the nearly complete search-space of all prima facie causes. We have tested these ideas in a number of domains and illustrate them here with two examples.
Kinetic Resolution of Protected α-Amino Acid Derivatives by a Chiral O-Nucleophilic Acyl Transfer Catalyst

The kinetic resolution of α-trifluoroacetamido N-acyl oxazolidinethiones using 5−10% of the chiral, nonracemic O-nucleophilic acyl transfer catalyst 2 is described. A variety of substrates participate in this reaction in excellent yields, with s-factors ranging from 20 to 86.
Statistical Properties of Magnetic Separators in Model Active Regions

Previous theoretical work suggests that magnetic reconnection in the solar corona should occur along particular topological boundaries in the coronal magnetic field known as separators. Thus, a field's topological structure predicts the locations of X-ray/EUV loops, assuming enhanced emission is related to reconnection. We use this topological model in a theoretical study of the statistical properties of active-region loops. We model the interaction of a single "test" element of photospheric magnetic flux with a much larger distribution of flux of the opposite polarity. We first model the large-scale distribution of flux in an active region using a mean-field approach and develop a procedure to determine separator lengths. We then perform Monte Carlo simulations to check the accuracy of this approximation. The results of both methods are similar and are well described by simple scaling laws for separator lengths. Separator lengths scale as ~exp(αr)/N1/2, where N parameterizes the flux in the large-scale distribution and r is the distance of the test element from the distribution's center. This scaling law is a theoretical prediction of X-ray loop lengths, which can be compared with observations.
Performance of the high brightness linac for the advanced free-electron laser initiative at Los Alamos

Abstract The AFEL accelerator has produced beams of 1 nC with peak currents greater than 100 A and a normalized, rms emittance less than 2π mm mrad. The 1300 MHz standing-wave accelerator uses on-axis coupling cells. The electron source is a photoinjector with a CsK 2 Sb photocathode. The photoinjector is an integral part of a single 11-cell accelerator structure. The accelerator operates between 12 and 18 MeV. The beam emittance growth in the accelerator is minimized by using a photoinjector, a focusing solenoid to correct the emittance growth due to space charge, and a special design of the coupling slots between accelerator cavities to minimize quadrupole effects. This paper describes the experimental results and compares those results with PARMELA simulation. The simulation code PARMELA was modified for this effort. This modified version uses SUPERFISH files for the accelerator cavity fields, MAFIA files for the fields due to the coupling slots in the accelerator cells, and POISSON files for the solenoid field in the gun region.
Engineering Carbon Nanotubes and Nanotube Circuits Using Electrical Breakdown

Carbon nanotubes display either metallic or semiconducting properties. Both large, multiwalled nanotubes (MWNTs), with many concentric carbon shells, and bundles or “ropes” of aligned single-walled nanotubes (SWNTs), are complex composite conductors that incorporate many weakly coupled nanotubes that each have a different electronic structure. Here we demonstrate a simple and reliable method for selectively removing single carbon shells from MWNTs and SWNT ropes to tailor the properties of these composite nanotubes. We can remove shells of MWNTs stepwise and individually characterize the different shells. By choosing among the shells, we can convert a MWNT into either a metallic or a semiconducting conductor, as well as directly address the issue of multiple-shell transport. With SWNT ropes, similar selectivity allows us to generate entire arrays of nanoscale field-effect transistors based solely on the fraction of semiconducting SWNTs.
Intelligent Acquisition and Learning of Fluorescence Microscope Data Models

We present a method for efficient acquisition of fluorescence microscope datasets, to allow for higher spatial and temporal resolution, and with less damage from photobleaching. Our proposal is to restrict acquisition to regions where we expect to find an object. Given that the objects are continuously moving, we must have an accurate model to describe objects' motion to predict their future locations. We outline a system for learning and applying this motion model, provide details from some simple simulations, and summarize results from more complex applications.
THE BIRTHPLACE OF LOW-MASS X-RAY BINARIES: FIELD VERSUS GLOBULAR CLUSTER POPULATIONS

Recent Chandra studies of low-mass X-ray binaries (LMXBs) within early-type galaxies have found that LMXBs are commonly located within globular clusters of the galaxies. However, whether all LMXBs are formed within globular clusters has remained an open question. If all LMXBs formed within globular clusters, the summed X-ray luminosity of the LMXBs in a galaxy should be directly proportional to the number of globular clusters in the galaxy regardless of where the LMXBs currently reside. We have compared these two quantities over the same angular area for a sample of 12 elliptical and S0 galaxies observed with Chandra and found that the correlation between the two quantities is weaker than expected if all LMXBs formed within globular clusters. This indicates that a significant number of the LMXBs were formed in the field and naturally accounts for the spread in field-to-cluster fractions of LMXBs from galaxy to galaxy. We also find that the "pollution" of globular cluster LMXBs into the field has been minimal within elliptical galaxies, but there is evidence that roughly half of the LMXBs originally in the globular clusters of S0 galaxies in our sample have escaped into the field. This is likely due to higher globular cluster disruption rates in S0s, resulting from stronger gravitational shocks caused by the passage of globular clusters through the disks of S0 galaxies that are absent in elliptical galaxies.
Neutrino Mass, Sneutrino Dark Matter and Signals of Lepton Flavor Violation in the MRSSM

We study the phenomenology of mixed-sneutrino dark matter in the Minimal R-symmetric Supersymmetric Standard Model (MRSSM). Mixed sneutrinos fit naturally within the MRSSM, as the smallness (or absence) of neutrino Yukawa couplings singles out sneutrino A-terms as the only ones not automatically forbidden by R-symmetry. We perform a study of randomly generated sneutrino mass matrices and find that (i) the measured value of Ω DM is well within the range of typical values obtained for the relic abundance of the lightest sneutrino, (ii) with small lepton-number-violating mass terms m nn 2 nn for the right-handed sneutrinos, random matrices satisfying the Ω DM constraint have a decent probability of satisfying direct detection constraints, and much of the remaining parameter space will be probed by upcoming experiments, (iii) the m nn 2 nn terms radiatively generate appropriately small Majorana neutrino masses, with neutrino oscillation data favoring a mostly sterile lightest sneutrino with a dominantly μ/τ-flavored active component, and (iv) a sneutrino LSP with a significant μ component can lead to striking signals of e-μ flavor violation in dilepton invariant-mass distributions at the LHC.
Ultrafast enhancement of ferromagnetism via photoexcited holes in GaMnAs.

We report on the observation of ultrafast photo-enhanced ferromagnetism in GaMnAs. It is manifested as a transient magnetization increase on a 100-ps time scale, after an initial sub-ps demagnetization. The dynamic magnetization enhancement exhibits a maximum below the Curie temperature {Tc} and dominates the demagnetization component when approaching {Tc}. We attribute the observed ultrafast collective ordering to the p-d exchange interaction between photoexcited holes and Mn spins, leading to a correlation-induced peak around 20K and a transient increase in {Tc}.
Reactions of Orthophthalaldehyde and Related Compounds with Amino Acids

Reaction of orthophthalaldehyde with thiols and of the product of this reaction with amino acids is commonly used for determination of amino acids. This reaction is often utilized in pre-column and post-column derivatization in chromatography and forms the basis of procedures applied in commercial amino acid analyzers. The product of this reaction is known to be an isoindole derivative, but the reaction paths of its formation are not understood. Better knowledge of chemical processes involved seems essential for development of more reliable procedures for determination of amino acids.
Maximizing system throughput using cooperative sensing in multi-channel cognitive radio networks

In Cognitive Radio Networks (CRNs), unlicensed users are allowed to access the licensed spectrum when it is not currently being used by primary users (PUs). To guarantee a high system throughput in CRNs, the channel state of PUs needs to be accurately detected to reduce conflict. To this end, cooperative spectrum sensing has been proposed to improve sensing accuracy by exploiting the spatial diversity of secondary users (SUs). However, existing works either focus on a single-channel setting, or make certain restrictive assumptions for multi-channel scenarios. In particular, most works on multi-channel CRNs place no limit on the number of channels that an SU can sense, which is impractical due to hardware and sensing duration constraints. In this paper, we study the throughput maximization problem for a multi-channel CRN where each SU can only sense a limited number of channels. We show that this problem is strongly NP-hard, and propose an approximation algorithm with a factor of equation, where l i is the number of channels that SU i can sense and N is the total number of SUs. This performance guarantee is achieved by exploiting a nice structural property, the subadditivity, of the objective function. Our numerical results demonstrate the advantage of our algorithm compared with both a random and a greedy sensing assignment algorithms.
Manumission in nineteenth-century Virginia

Using previously unexploited data, this paper explores the ages at which slaves were manumitted. OLS estimates reveal that mixed-race slaves, slaves in the tobacco-producing Piedmont, and female slaves of female slave owners were manumitted at younger ages. Weibull proportional hazards estimates imply that the same groups were more likely to be manumitted. The results also reveal a markedly diminishing likelihood of manumission after Nat Turner’s 1831 insurrection in south-central Virginia. The results are consistent with a principal–agent model in which slave owners contracted with slaves over consumption and future manumission to elicit effort and control shirking or other unproductive activities.
Opportunistic third-party backhaul for cellular wireless networks

With high capacity air interfaces and large numbers of small cells, backhaul — the wired connectivity to base stations — is increasingly becoming the cost driver in cellular wireless networks. One reason for the high cost of backhaul is that capacity is often purchased on leased lines with guaranteed rates provisioned to peak loads. In this paper, we present an alternate opportunistic backhaul model where third parties provide base stations and backhaul connections and lease out excess capacity in their networks to the cellular provider when available, presumably at significantly lower costs than guaranteed connections. We describe a scalable architecture for such deployments using open access femtocells, which are small plug-and-play base stations that operate in the carrier's spectrum but can connect directly into the third-party provider's wired network. Within the proposed architecture, we present a general user association optimization algorithm that enables the cellular provider to dynamically determine which mobiles should be assigned to the third-party femtocells based on the traffic demands, interference and channel conditions and third-party access pricing. Although the optimization is non-convex, the algorithm uses a computationally efficient method for finding approximate solutions via dual decomposition. Simulations of the deployment model based on actual base station locations are presented that show that large capacity gains are achievable if adoption of third-party, open access femtocells can reach even a small fraction of the current market penetration of WiFi access points.
The Impact of Recent Generic Drug Price Policies on Pharmaceutical Innovation: A Theoretical Rationale and Proposal of a Method Supporting Innovation in Areas of Unmet Medical Need

New discoveries are a critical priority for the pharmaceutical industry. However, the use of fixed incremental cost-effectiveness (ICER) thresholds for health technology assessment (HTA) may compromise incentives to innovate and affect future treatment options. This paper highlights the impact of generic drug price policies on pharmaceutical innovation in the context of fixed ICER thresholds and proposes a new consideration for the cost-effectiveness analysis (CEA). There is a direct causal relationship between HTA and the market price of a drug; in jurisdictions where HTA agencies apply fixed ICER thresholds as an important reimbursement listing criterion, the incremental cost of a new drug is expected to be proportional to its incremental benefit over the comparator. However, the comparator price is subject to market forces or sudden policies and may change markedly affecting the cost-effectiveness assessment (e.g. where the comparator patent has expired). Since recent generic price regulations increased the price gap between drugs’ generic and patented versions, it is harder to achieve a sufficient level of incremental benefits in order to offset incremental prices of new treatments. Consequently, even promising drugs may have challenges to show attractive ICERs and research and development (R&D) investments may become unattractive in certain disease area. In order to promote innovation in therapeutic fields with unmet medical needs, a compromise would be to include the comparator’s patented price in the CEA instead of the generic drug. By identifying the relevant disease areas, decision makers and HTA authorities could therefore convey the importance of investing in these therapeutic areas to manufacturers.
Modeling Nonaxisymmetric Bow Shocks: Solution Method and Exact Analytic Solutions

A new solution method is presented for steady-state, momentum-conserving, non-axisymmetric bow shocks and colliding winds in the thin-shell limit.
Optimal investment strategy to minimize occupation time

We find the optimal investment strategy to minimize the expected time that an individual’s wealth stays below zero, the so-called occupation time. The individual consumes at a constant rate and invests in a Black-Scholes financial market consisting of one riskless and one risky asset, with the risky asset’s price process following a geometric Brownian motion. We also consider an extension of this problem by penalizing the occupation time for the degree to which wealth is negative.
Extremal black holes as fundamental strings

Abstract We show that polarization-dependent string-string scattering provides new evidence for the identification of the Dabholkar-Harvey (DH) string solution with the heterotic string itself. First, we construct excited versions of the DH solution which carry arbitrary left-moving waves yet are annihilated by half the supersymmetries. These solutions correspond in a natural way to Bogomolny-bound-saturating excitations of the ground state of the heterotic string. When the excited string solutions are compactified to four dimensions, they reduce to Sen's family of extremal black hole solutions of the toroidally compactified heterotic string. We then study the large impact parameter scattering of two such string solutions. We develop methods which go beyond the metric on moduli space approximation and allow us to read off the subleading polarization-dependent scattering amplitudes. We find perfect agreement with heterotic string tree amplitude predictions for the scattering of corresponding string states. Taken together, these results clearly identify the string states responsible for Sen's extremal black hole entropy. We end with a brief discussion of implications for the black hole information problem.
Nonlinear Filtering for Low-Velocity Gaseous Microflows

Gaseous flows in microfluidic devices are often characterized by relatively high Knudsen numbers. For such flows, the continuum approximation is not valid, and direct simulation Monte Carlo (DSMC) may be used to find an appropriate solution. For low-velocity flows, where the fluid velocity is much smaller than the mean molecular velocity, large statistical fluctuations in the solution mean that the features of the flow may be obscured by noise in the solution. The use of a high-order, nonlinear monotone convection algorithm, flux-corrected transport (FCT), as a filter to extract the solution from the noisy DSMC calculation is described. The diffusion, antidiffusion, and flux-limiting properties of FCT are discussed in terms of their filtering properties. The effects of filtering with FCT are demonstrated for a series of test problems, including a square wave with superimposed random noise, and low-and high-velocity and low- and high-Knudsen-number microchannel flows
Complexity in the immune system

The immune system is a real-time example of an evolving system that navigates the essentially infinite complexity of protein sequence space. How this system responds to disease and vaccination is discussed. Of particular focus is the case when vaccination leads to increased susceptibility to disease, a phenomenon termed original antigenic sin. A physical theory of protein evolution to explain limitations in the immune system response to vaccination and disease is discussed, and original antigenic sin is explained as stemming from localization of the immune system response in antibody sequence space. This localization is a result of the roughness in sequence space of the evolved antibody affinity constant for antigen and is observed for diseases with high year-to-year mutation rates, such as influenza.
Monolithic packaging concepts for high isolation in circuits and antennas

High-frequency planar circuits experience large electromagnetic (EM) coupling in dense circuit environments. As a result, individual components exhibit performance degradation that ultimately limits overall circuit response. This paper addresses crosstalk in planar microstrip lines by evaluating micromachined packages as a means to reduce coupling. Microstrip lines with straight and meandering paths can exhibit crosstalk coupling as high as -20 dB (i.e., when placed in a side-by-side arrangement). From our study, inclusion of a monolithic package reduces this effect by as much as -30 dB and, consequently, offers the requisite electrical and environmental protection in addition to shielding of individual elements from parasitic radiation. Presented herein is the development of the micromachined package for microstrip geometries. Included in the discussion are crosstalk effects between straight and bending geometries in open and packaged configurations and an evaluation of package noise characteristics. A packaged antenna element is also included as a demonstration of the potential use of micromachined packaging in array applications.
3-MANIFOLD INVARIANTS FROM COSETS

We construct unitary modular categories for a general class of coset conformal field theories based on our previous study of these theories in the algebraic quantum field theory framework using subfactor theory. We also consider the calculations of the corresponding 3-manifold invariants. It is shown that under certain index conditions the link invariants colored by the representations of coset factorize into the products of the the link invariants colored by the representations of the two groups in the coset. But the 3-manifold invariants do not behave so simply in general due to the nontrivial branching rules of the coset. Examples in the parafermion cosets and diagonal cosets show that 3-manifold invariants of the coset may be finer than the products of the 3-manifold invariants associated with the two groups in the coset, and these two invariants do not seem to be simply related in some cases, for an example, in the cases when there are issues of "fixed point resolutions". In the later case our framework provides a representation theory understanding of the underlying unitary modular categories which has not been obtained before.
Development of a high Reynolds number quiet tunnel for transition research

High noise levels in conventional supersonic and hypersonic wind tunnels prevent further advances in transition research. Recent data confirm previous results that transition is dominated by tunnel noise when the rms pressure intensities exceed about 1%. High facility noise levels also dominate fluctuating pressure loads under fully turbulent boundary layers. Recent data on the power spectra of surface pressures indicate that the basic structure of turbulent boundary layers may be modified by high facility noise levels. Experimental data for current techniques to control and reduce noise levels in supersonic and hypersonic wind tunnels by laminarization of nozzle wall boundary layers and by noise radiation shields are presented. These results and possible effects of Taylor-Gortler vortices observed in a nozzle wall boundary layer are used to predict the limits of quiet performance for a proposed 20-in. quiet tunnel.
Corporate Incentives for Hedging and Hedge Accounting

This article explores the information effect of financial risk management. Financial hedging improves the informativeness of corporate earnings as a signal of management ability and project quality by eliminating extraneous noise. Managerial and shareholder incentives regarding information transmission may differ, however, leading to conflicts regarding an optimal hedging policy. We show that these incentives depend on the accounting information made available by the firm. Under some circumstances, if hedge transactions are not disclosed (i.e., firms report only aggregate earnings), managers hedge to achieve greater risk reduction than they would if full disclosure were required. In these cases, it is optimal for shareholders to request only aggregate accounting reports. Article published by Oxford University Press on behalf of the Society for Financial Studies in its journal, The Review of Financial Studies.
Decorrelating the power spectrum of galaxies

We show how to decorrelate the (pre-whitened) power spectrum measured from a galaxy survey into a set of high-resolution uncorrelated band-powers. The treatment includes non-linearity, but not redshift distortions. Amongst the infinitely many possible decorrelation matrices, the square root of the Fisher matrix, or a scaled version thereof, offers a particularly good choice, in the sense that the band-power windows are narrow, approximately symmetric, and well-behaved in the presence of noise. We use this method to compute band-power windows for, and the information content of, the Sloan Digital Sky Survey, the Las Campanas Redshift Survey, and the IRAS 1.2-Jy Survey.
Classical and robust H(infinity) control redesign for the Hubble Space Telescope

A control redesign problem of the Hubble Space Telescope for reducing the effects of solar array vibrations on telescope pointing jitter is investigated. Both classical and H, control design methodologies are employed for such a control problem with a non-colocated actuator and sensor pair. This paper successfully demonstrates the effectiveness of a dipole concept for precision line-ofsight pointing control in the presence of significant structural vibrations. Proposed controllers with two dipoles effectively reduce the effects of the solar array induced disturbances at 0.12 Hz and 0.66 Hz on pointing jitter.
Quantum-dot cellular automata

An introduction to the operation of quantum-dot cellular automata is presented, along with recent experimental results. Quantum-dot cellular automata (QCA) is a transistorless computation paradigm that addresses the issues of device density and interconnection. The basic building blocks of the QCA architecture, such as AND, OR, and NOT are presented. The experimental device is a four-dot QCA cell with two electrometers. The dots are metal islands, which are coupled by capacitors and tunnel junctions.
Saving and growth in Egypt

This study illustrates the mechanisms linking national saving and economic growth, with the purpose of understanding the possibilities and limits of a saving-based growth agenda in the context of the Egyptian economy. This is done through a simple theoretical model, calibrated to fit the Egyptian economy, and simulated to explore different potential scenarios. The main conclusion is that if the Egyptian economy does not experience progress in productivity -- stemming from technological innovation, improved public management, and private-sector reforms -- then a high rate of economic growth is not feasible at current rates of national saving and would require a saving effort that is highly unrealistic. For instance, financing a constant 4 percent growth rate of gross domestic product per capita with no improvement in total factor productivity would require a national saving rate of around 50 percent in the first decade and 80 percent in 25 years. However, if productivity rises, sustaining and improving high rates of economic growth becomes viable. Following the previous example, a 2 percent growth rate of total factor productivity would allow a 4 percent growth rate of gross domestic product per capita with national saving rate in the realistic range of 20-25 percent of gross domestic product.
Strategies for mechanism reduction for large hydrocarbons: n-heptane

A 55-species reduced mechanism for n-heptane oxidation was derived from a 188-species skeletal mechanism, which was previously obtained from a detailed mechanism consisting of 561 species using a directed relation graph (DRG). This reduced mechanism was derived by first obtaining a skeletal mechanism with 78 species using DRG-aided sensitivity analysis. The unimportant reactions were eliminated by using the importance index defined in computational singular perturbation (CSP), with a newly posited restriction to treat each reversible reaction as a single reaction. An isomer lumping approach, also developed in the present study, then groups the isomers with similar thermal and diffusion properties so that the number of species transport equations is reduced. It was found that the intragroup mass fractions of the isomers can be approximated as constants in the present reduced mechanism, leading to a 68-species mechanism with 283 elementary reactions. Finally, 13 global quasi-steady-state species were identified using a CSP-based time-scale analysis, resulting in the 55-species reduced mechanism, with 283 elementary reactions lumped into 51 semiglobal steps. Validation of the reduced mechanism shows good agreement with the detailed mechanism for both ignition and extinction phenomena. The inadequacy of the detailed mechanism in predicting the experimental laminar flame speed is also demonstrated.
Immersed surfaces and Seifert fibered surgery on Montesinos knots

We will use immersed surfaces to study Seifert fibered surgery on Montesinos knots, and show that if 1 q1−1 + 1 q2−1 + 1 q3−1 ≤ 1 then a Montesinos knot K(p q1 , p2 q2 , p3 q3 ) admits no atoroidal Seifert fibered surgery.
Multiple ergodic averages for three polynomials and applications

We find the smallest characteristic factor and a limit formula for the multi- ple ergodic averages associated to any family of three polynomials and polynomial fam- ilies of the form {l1p,l2p,...,lkp}. We then derive several multiple recurrence results and combinatorial implications, including an answer to a question of Brown, Graham, and Landman, and a generalization of the Polynomial Szemeredi Theorem of Bergelson and Leibman for families of three polynomials with not necessarily zero constant term. We also simplify and generalize a recent result of Bergelson, Host, and Kra, showing that for all " > 0 and every subset of the integersthe set
Group velocity of large-amplitude electromagnetic waves in a plasma.

The nonlinear group velocity of a laser pulse propagating in a cold underdense unmagnetized plasma is examined. Analytical expressions for the group velocity are derived for various pulse length regimes. These expressions reduce to the usual [partial derivative][omega]/[partial derivative][ital k] form for small amplitude and are verified for aribtrary amplitude using particle in cell simulations on a cyclic mesh. We find that the leading edge of a pulse moves at the linear group velocity and that the phase velocity of the excited wake is less than the group velocity of the pulse for symmetrically shaped pulses. The techniques used can be applied to other waves in a plasma.