cssi/SciSciGPT-SciSciNet huggingface dataset:
COSMIC-RAY ELECTRON EVOLUTION IN THE SUPERNOVA REMNANT RX J1713.7–3946

A simple formalism to describe nonthermal electron acceleration, evolution, and radiation in supernova remnants (SNRs) is presented. The electron continuity equation is analytically solved assuming that the nonthermal electron injection power is proportional to the rate at which the kinetic energy of matter is swept up in an adiabatically expanding SNR shell. We apply this model to Fermi and HESS data from the SNR RX J1713.7–3946 and find that a one-zone leptonic model with Compton-scattered cosmic microwave background and interstellar infrared photons has difficulty providing a good fit to its spectral energy distribution, provided the source is at a distance ~1 kpc from the Earth. However, the inclusion of multiple zones, as hinted at by recent Chandra observations, does provide a good fit, but requires a second zone of compact knots with magnetic fields B ~ 16 μG, comparable to shock-compressed fields found in the bulk of the remnant.
Conditional negative association for competing urns

We prove conditional negative association for random variables xj = 1**math-image** (j∈[n]:= {1…n}) , where σ(1)…σ(m) are i.i.d. from [n]. (The σ(i) 's are thought of as the locations of balls dropped independently into urns 1…n according to some common distribution, so that, for some threshold tj, xj is the indicator of the event that at least tj balls land in urn j.) We mostly deal with the more general situation in which the σ(i) 's need not be identically distributed, proving results which imply conditional negative association in the i.i.d. case. Some of the results—particularly Lemma 8 on graph orientations—are thought to be of independent interest. We also give a counterexample to a negative correlation conjecture of D. Welsh, a strong version of a (still open) conjecture of G. Farr. © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 2012 © 2012 Wiley Periodicals, Inc.
Critical slowing-down in SU(2) Landau gauge-fixing algorithms

Abstract We study the problem of critical slowing-down for gauge-fixing algorithms (Landau gauge) in SU(2) lattice gauge theory on a 2-dimensional lattice. We consider five such algorithms, and lattice sizes ranging from 8 2 to 36 2 (up to 64 2 in the case of Fourier acceleration). We measure four different observables and we find that for each given algorithm they all have the same relaxation time within error bars. We obtain that the so-called Los Alamos method has a dynamic critical exponent z ≈ 2, the overrelaxation method and the stochastic overrelaxation method have z ≈ 1, the so-called Cornell method has z slightly smaller than 1 and the Fourier acceleration method completely eliminates critical slowing-down. A detailed discussion and analysis of the tuning of these algorithms is also presented.
A geometric classification of some solvable groups of homeomorphisms

We investigate subgroups of the group PLo(I) of piecewise-linear, orientation-preserving homeomorphisms of the unit interval with finitely many breaks in slope, under the operation of composition, and also subgroups of generalized Thompson groups Fn. We find geometric criteria determining the derived length of any such group, and use these criteria to produce a geometric classification of the solvable and non-solvable subgroups of PLo(I) and of the Fn. We also show that any standard restricted wreath product (of non-trivial groups) that embeds in PLo(I) or Fn must have T
Monte Carlo simulations of spin glasses at low temperatures: Effects of free boundary conditions

We present results of Monte Carlo simulations, using parallel tempering, on the three- and four-dimensional Edwards-Anderson Ising spin glass with Gaussian couplings at low temperatures with free boundary conditions. Our results suggest that the surface of large-scale low-energy excitations may be space filling. The data implies that the energy of these excitations increases with increasing system size for small systems, but we see evidence in three dimensions, where we have a greater range of sizes, for a crossover to a regime where the energy is independent of system size, in accordance with replica symmetry breaking.
Local Radiative Hydrodynamic and Magnetohydrodynamic Instabilities in Optically Thick Media

We examine the local conditions for radiative damping and driving of short-wavelength, propagating hydrodynamic and magnetohydrodynamic (MHD) waves in static, optically thick, stratified equilibria. We show that so-called strange modes in stellar oscillation theory and magnetic photon bubbles are intimately related and are both fundamentally driven by the background radiation flux acting on compressible waves. We identify the necessary criteria for unstable driving of these waves and show that this driving can exist in both gas pressure- and radiation pressure-dominated media, as well as pure Thomson scattering media in the MHD case. The equilibrium flux acting on opacity fluctuations can drive both hydrodynamic acoustic waves and magnetosonic waves unstable. In addition, magnetosonic waves can be driven unstable by a combination of the equilibrium flux acting on density fluctuations and changes in the background radiation pressure along fluid displacements. We briefly describe the conditions under which these instabilities might be manifested in both main-sequence stellar envelopes and accretion disks.
Market discipline and monetary policy

The effects of forward looking expectations of future inflation on equilibrium inflation and interest rates are examined within an imperfect information framework. Expectations of future inflation affect equilibrium in a manner similar to an increase in the central bank's weight on future social welfare, making it more likely an opportunistic central bank will actually deliver on its announced inflation targets, and output expansions can arise even if the central banker is revealed to be a low inflation type. The model also illustrates the channels through which inflation scares raise current real interest rates. Copyright 2000 by Oxford University Press.
IBM current mode transistor logical circuits

The current mode circuits discussed in this paper and in preceding papers are intended for use in a very large, high-speed digital computer. From the circuit standpoint, this machine could be classed as a mixed synchronous-asynchronous system in which the outputs of chains of logic are often sampled by clock pulses. The system requires circuits which have delays of approximately 20 millimicroseconds per circuit. The basic circuit philosophy discussed here is well suited to the properties of the drift transistor.
QCD with large number of quarks: effects of the instanton - anti-instanton pairs

Abstract We calculate the contribution of instanton – anti-instanton ( I I ) pairs to the vacuum energy of QCD-like theories with N f light fermions, using the saddle point method. A qualitative change of behavior is found around N f =6. We discuss the relation of this phenomenon to the mechanism of chiral symmetry breaking and the asymptotic of the perturbative series associated with I I contributions.
Simplified fabrication of back surface electric field silicon cells and novel characteristics of such cells

Abstract An investigation of the characteristics and behavior of 10 Ω cm Si cells which have abnormally high open-circuit voltages was made. The cells studied were made by a new, highly simplified, contact fabrication process which creates both a contact and a thin electric field region at the cell back surface without the need for phosphorus layer removal. These cells had open-circuit voltages of about 0.58 V and their performance as a function of thickness, temperature, and 1 MeV electron irradiation is described. The study showed that 10 Ω cm back-surface-filed cells can have the high initial efficiencies and desirable temperature behavior of low resistivity cells. Thin back surface field cells were made and showed, in addition, much greater radiation damage resistance. A mechanism is proposed to explain the results.
Structure–property relationships for metal-free organic magnetic materials

Abstract This chapter gives an introduction to the basic concepts of magnetism in organic paramagnetic soft matter materials. Key concepts are emphasized using example case studies. Detailed analysis covers radicals functionalized with phenols and with benzimidazole functionalities, which induce various degrees of crystal self-assembly, depending on specific structures. A review with over 200 references and notes.
The distribution of points on superelliptic curves over finite fields

We give the distribution of points on smooth superelliptic curves over a fixed finite field, as their degree goes to infinity. We also give the distribution of points on smooth m-fold cyclic covers of the line, for any m, as the degree of their superelliptic model goes to infinity. This builds on previous work of Kurlberg, Rudnick, Bucur, David, Feigon, and Lalin for p-fold cyclic covers, but the limits taken differ slightly and the resulting distributions are interestingly different.
The Sato-Tate conjecture for Hilbert modular forms

We prove the Sato-Tate conjecture for Hilbert modular forms. More precisely, we prove the natural generalisation of the Sato-Tate conjecture for regular algebraic cuspidal automorphic representations of GL2(AF ), F a totally real field, which are not of CM type. The argument is based on the potential automorphy techniques developed by Taylor et. al., but makes use of automorphy lifting theorems over ramified fields, together with a “topological” argument with local deformation rings. In particular, we give a new proof of the conjecture for modular forms, which does not make use of potential automorphy theorems for non-ordinary n-dimensional Galois representations.
Giant magnetoresistance and microstructural characteristics of epitaxial Fe‐Ag and Co‐Ag granular thin films

The microstructure and magnetic properties of phase‐separated Fe‐Ag and Co‐Ag granular alloy films, grown epitaxially on (001) NaCl substrates and exhibiting giant magnetoresistance (GMR), have been investigated. Surprisingly, two Fe‐Ag films of similar composition grown under identical conditions are found to have substantially different microstructures yet display similar GMR. The microstructure of the films is characterized by Fe‐rich or Co‐rich regions, respectively, 350–700 nm in extent, surrounded by a Ag‐rich matrix. Within the Ag‐rich regions, the Fe concentration varies from 20 to 25 at % and the Co concentration is ≂16 at %. Within these regions essentially pure fcc Co particles and bcc Fe particles are in parallel and rotated epitaxial alignment respectively with the fcc silver matrix. The Co and Fe particles are ≂15–25 A in diameter. It is these small particles which most likely account for the giant magnetoresistance exhibited by these alloys. This suggests that a size distribution of magneti...
Self-intersections in combinatorial topology: statistical structure

Oriented closed curves on an orientable surface with boundary are described up to continuous deformation by reduced cyclic words in the generators of the fundamental group and their inverses. By self-intersection number one means the minimum number of transversal self-intersection points of representatives of the class. We prove that if a class is chosen at random from among all classes of m letters, then for large m the distribution of the self-intersection number approaches the Gaussian distribution. The theorem was strongly suggested by a computer experiment with four million curves producing a very nearly Gaussian distribution.
Climate prediction for adaptation: Who needs what?

The role of short- and long-term climate predictions in determining the success of adaptation to climate change is investigated. A simple theoretical model that captures the relationship between adaptive performance, decision structure, and prediction accuracy at different temporal scales is developed, and its implications deduced. It is shown that users who face high adjustment costs (i.e. are inflexible) depend more heavily on accurate long-term predictions than those who are able to adjust their adaptation strategies at low cost. However, the constraints on the accuracy of long-term predictions in order for them to be ‘accurate enough’ to be recommended unreservedly are strongest for precisely those users who desire them most. There are thus intrinsic structural limitations to the utility of long-term predictions for adaptive decision making. In addition, the heterogeneous dependence of adaptive performance on predictions at different temporal scales gives rise to a resource allocation problem for investments aimed at improving predictions so as to maximize their social benefits. It is suggested that an explicit distributional framework that matches users’ needs with scientific feasibility is needed in order to guide such investments, and key issues any such framework will need to address are discussed.
The synthesis of monomethoxynaphtho[1',2':4,5]thieno[2,3-c]quinolines

A series of monomethoxynaphtho[1′,2′:4,5]thieno[2,3-c]quinolines has been prepared by photocyclization of the appropriate N-methoxyphenyl-1-chloronaphtho[2,1-b]thiophene-2-carboxamides. Some of the lactams obtained were converted into the thiolactams and their S-methyl derivatives. The lactams were also converted into the corresponding 6-chloro derivatives. Some of these were catalytically dechlorinated into the monomethoxynaphtho[1′,2′:4,5]thieno[2,3-c]quinolines which were then quaternized into the N-methyl quaternary salts.
Magnetic monopoles as a new solution to strong CP problem

Abstract A non-perturbative solution to strong CP problem is proposed. It is shown that the gauge orbit space with gauge potentials and well-defined gauge transformations topologically restricted on the space boundary in non-abelian gauge theories with a θ term has a monopole structure if there is a magnetic monopole in the ordinary space. The Dirac's quantization condition in the corresponding quantum theories ensures that the vacuum angle θ in the gauge theories must be quantized. The quantization rule for θ is derived as θ = 0,2π/n (n ≠ 0) with n being the topological charge we obtain for the magnetic monopole. Therefore, the strong CP problem is automatically solved non-perturbatively in the presence of magnetic monopoles, with charge ±1 so that θ = ±2π, or with a very large (|n| ⩾ 109 × 2π) total topological charge for the same generator, or with non-abelian monopoles of more than one non-zero ni corresponding to color SU(3) so that the relevant effective θ = 0. The fact that the strong CP violation can be only so small or vanishing may be a signal for the existence of magnetic monopoles and the universe is open. If there exists an axion field a(x), the value of the physical axion field aphy(x) will not be quantized. However, the expectation value of the CP violating density ϵμνγσFμσaFγσa will be quantized. For the special values of the topological number n, it can be vanishing or very small even without using the Peccei-Quinn dynamical adjusting. In the usual gauge theories without magnetic monopoles, there may be at most a Z2 monopole structure in the gauge orbit space in SP(2N) gauge theories.
Reduced-Order Cue-Signal-Response Modeling for Angiogenic Cell Migration Control: A Principal Signal Approach

A cell’s behavior in response to stimuli is governed by a signaling network, called cue-signal-response. Endothelial Cells (ECs), for example, migrate towards the source of chemo-attractants by detecting cues (chemo-attractants and their concentration gradient), feeding them into an intra-cellular signaling network (coded internal state), and producing a response (migration). It is known that the cue-signal-response process is a nonlinear, dynamical system with high dimensionality and stochasticity. This paper presents a system dynamics approach to modeling the cue-signal-response process for the purpose of manipulating and guiding the cell behavior through feedback control. A Hammerstein type model is constructed by representing the entire process in two stages. One is the cue-to-signal process represented as a nonlinear feedforward map, and the other is the signal-to-response process as a stochastic linear dynamical system, which contains feedback loops and auto-regressive dynamics. Analysis of the signaling space based on Singular-Value Decomposition yields a set of reduced order synthetic signals, which are used as inputs to the dynamical system. A prediction-error method is used for identifying the model from experimental data, and an optimal system order is determined based on Akaike’s Information Criterion. The resultant low order model is capable of predicting the expected response to cues, and is directly usable for feedback control. The method is applied to an in vitro angiogenic process using microfluidic devices.Copyright © 2010 by ASME
Separation of coal-derived liquids by gel permeation chromatography

Abstract Coal-derived liquids, obtained from pilot plants and bench-scale reactors, have been separated by gel permeation chromatography into aromatic, phenolic, and asphaltenic fractions, where asphaltenes and long-chain hydrocarbons are in the same fraction. The Chromatographie system uses 10 nm μStyragel columns and solvents such as tetrahydrofuran (THF) and toluene. The separation is reasonably clean and almost devoid of overlapping. The saturated hydrocarbons are separated from the asphaltenes by vacuum distillation. Aromatic, phenolic and aliphatic fractions are characterized by high-resolution gas chromatography—mass spectrometry. The phenolic fraction contains alkylated phenols, indanols, and naphthols. The aromatic fraction is composed of alkylated benzenes, indans, naphthalenes and small amounts of multi-ring aromatics such as alkylated fluorenes and pyrenes. Most of the long-chain hydrocarbon fraction is of straight-chain alkanes ranging from tetradecane to tetratetracontane. Some branched alkanes, such as pristane and phytane, are also present. If olefins are present in the sample they also separate with the long-chain hydrocarbon fraction. Although various analytical data such as i.r., n.m.r., molecular size distribution and elemental composition of asphaltenes have been obtained, the chemical characterization is not complete. The gel permeation Chromatographie separation technique, as discussed in this paper, is very useful for fast analysis of any coal-derived liquid.
CORRELATIONS OF QUASAR OPTICAL SPECTRA WITH RADIO MORPHOLOGY

Using the largest homogeneous quasar sample with high-quality optical spectra and robust radio morphology classifications assembled to date, we investigate relationships between radio and optical properties with unprecedented statistical power. The sample consists of 4714 radio quasars from FIRST with S 20 ? 2 mJy and with spectra from the Sloan Digital Sky Survey (SDSS). Radio morphology classes include core-only (core), core-lobe (lobe), core-jet (jet), lobe-core-lobe (triple), and double-lobe. Electronic tables of the quasar samples, along with spectral composites for individual morphology classes, are made available. We examine the optical colors of these subsamples and find that radio quasars with core emission unresolved by FIRST (on ~5'' scale) have a redder color distribution than radio-quiet quasars (S 20 1 mJy); other classes of radio quasars have optical color distributions similar to the radio-quiet quasars. This analysis also suggests that optical colors of z 2.7 SDSS quasars are not strongly (<0.1?mag) biased blue. We show that the radio core-to-lobe flux density ratio (R) and the radio-to-optical (i-band) ratio of the quasar core (R I) are correlated, which supports the hypothesis that both parameters are indicative of line-of-sight orientation. We investigate spectral line equivalent widths (EWs) as a function of R and R I, including the O [III] narrow line doublet and the C IV ?1549 and Mg II ?2799 broad lines. We find that the rest EWs of the broad lines correlate positively with R I at the 4?-8? level. However, we find no strong dependence of EW on R, in contrast to previously published results. A possible interpretation of these results is that EWs of quasar emission lines increase as the line-of-sight angle to the radio-jet axis decreases. These results are in stark contrast to commonly accepted orientation-based theories, which suggest that continuum emission should increase as the angle to the radio-jet axis decreases, resulting in smaller EWs of emission lines (assumed isotropic). Finally, we observe the Baldwin effect in our sample and find that it does not depend strongly on quasar radio morphology.
Two-way communication with adaptive data acquisition

A bidirectional link between two nodes, Node 1 and Node 2, is studied in which Node 2 is able to acquire information from the environment, e.g., via access to a remote data base or via sensing. Information acquisition is expensive in terms of system resources, e.g., time, bandwidth and energy, and thus should be done efficiently. As a result of the forward communication from Node 1 to Node 2, the latter wishes to obtain information about the the data available at Node 1 and of the data obtained from the environment. The forward link is, however, also used by Node 1 to query Node 2 with the aim of retrieving information from the environment on the backward link. The problem is formulated using the concept of side information “vending machine”, and the optimal trade-off between communication rates, distortions of the estimates produced at the two nodes and costs for information acquisition at Node 2 is derived.
MASS TO LIGHT RATIOS OF GROUPS AND CLUSTERS OF GALAXIES

We constrain the mass-to-light ratios, gas mass fractions, baryon mass fractions and the ratios of total to luminous mass for a sample of eight nearby relaxed galaxy groups and clusters: A262, A426, A478, A1795, A2052, A2063, A2199 and MKW4s. We useASCA spatially resolved spectroscopic X-ray observations and ROSAT PSPC images to constrain the total and gas masses of these clusters. To measure cluster luminosities we use galaxy catalogs resulting from the digitization and automated processing of the second generation Palomar Sky Survey plates calibrated with CCD images in the Gunn-Thuan g, r, and i bands. Under the assumption of hydrostatic equilibrium and spherical symmetry, we can measure the total masses of clusters from their intra-cluster gas temperature and dens ity profiles. Spatially resolved ASCA spectra show that the gas temperature decreases with increasing distance from the center. By comparison, the assumption that the gas is isothermal results in an underestimate of the total ma ss at small radii, and an overestimate at large cluster radii. We have obtained luminosity functions for all clusters in our sample. After correcting for background and foreground galaxies, we estimate the total cluster luminosity using Schechter function fits to the galaxy catalogs. In the three lowest redshift clusters where we can sample to fainter absolute magnitudes, we have detected a flattening of the luminosity function at intermediate magni tudes and a rise at the faint end. These clusters were fitted with a sum of two Schechter functions. The remaining cl usters were well fitted with a single Schechter function. Assuming H0 = 50 h50 km s -1 Mpc -1 , the measured mass-to-light ratios are ∼ 100 h50 M⊙/L⊙. This, along with a high baryonic fraction, is indicative of a low density universe with 0 ∼ 0.15 - 0.2. Subject headings: Cosmology — galaxies: clusters: individual — intergalactic medium — X-rays: galaxies
Value-of-information aware active task assignment

This paper discusses the problem of robust allocation of unmanned vehicles (T.N) to targets with uncertainties. In particular, the team consists of heterogeneous vehicles with different exploration and exploitation abilities. A general framework is presented to model uncertainties in the planning problems, which goes beyond traditional Gaussian noise. Traditionally, exploration and exploitation are decoupled into two assignment problems are planned with un-correlated goals. The coupled planning method considered here assign exploration vehicles based on its potential influence of the exploitation. Furthermore, a fully decentralized algorithm, Consensus-Based Bundle Algorithm (CBBA), is used to implement the decoupled and coupled methods. CBBA can handle system dynamic constraints such as target distance, vehicle velocities, and has computation complexity polynomial to the number of vehicles and targets. The coupled method is shown to have improved planning performance in a simulated scenario with uncertainties about target classification.
On the structure group of a decomposable model space

We give a complete classification of the structure group of a direct sum of canonical algebraic curvature tensors. We use this classification to construct new invariants of the corresponding model spaces, and give two geometric examples where a knowledge of this classification is useful.
Reflexivity and rigidity for complexes, I: Commutative rings

A notion of rigidity with respect to an arbitrary semidualizing complex C over a commutative noetherian ring R is introduced and studied. One of the main results characterizes C-rigid complexes. Specialized to the case when C is the relative dualizing complex of a homomorphism of rings of finite Gorenstein dimension, it leads to broad generalizations of theorems of Yekutieli and Zhang concerning rigid dualizing complexes, in the sense of Van den Bergh. Along the way, new results about derived reflexivity with respect to C are established. Noteworthy is the statement that derived C-reflexivity is a local property; it implies that a finite R-module M has finite G-dimension over R if Mm has finite G-dimension over Rm for each maximal ideal m of R.
Dirac Spectrum, Axial Anomaly and the QCD Chiral Phase Transition

The QCD phase transition is studied on 16 3 and 32 3 × 4 lattices both with and without quark loops. We introduce a new zero-flavor or quenched species of quark ζ and study the resulting chiral condensate, 〈 ζ ¯ ζ 〉 as a function of the ζ mass, m ζ . By examining 〈 ζ ¯ ζ 〉 for 10 −10 ≤ m ζ ≤ 10 we gain considerable information about the spectrum of Dirac eigenvalues. A comparison of ma = 0.01 and 0.025 shows little dependence of the Dirac spectrum on such a light, dynamical quark mass, after an overall shift in β is removed. The presence of sufficient small eigenvalues to support anomalous chiral symmetry breaking in the high temperature phase is examined quantitatively. In an effort to enhance these small eigenvalues, 〈 ζ ¯ ζ 〉 is also examined in the pure gauge theory in the region of the deconfinement transition with unexpected results. Above the critical temperature, the three Z 3 phases show dramatically different chiral behavior. Surprisingly, the real phase shows chiral symmetry, suggesting that a system with one flavor of staggered fermion at N t = 4 will possess a chiral a phase transition—behavior not expected in the continuum limit.
Diffraction gratings at the Mount Wilson Observatory

The past century has seen major advances in diffraction gratings, motivated by pressure for new and better data in two rather distinct fields: laboratory spectroscopy—aimed at understanding atomic structure and testing quantum theory—and astrophysical spectroscopy—aimed at understanding objects ranging from the Sun and stars to faint sources at the limit of detection. In this historical account I trace some of the hard‐won gains in the technology of the ruling machines that produce the gratings, and I touch on the role that larger and higher‐quality gratings have played in scientific advances. I focus on the work at the Mount Wilson Observatory, where I directed the diffraction‐grating laboratory from 1948 to 1963, but I do so with full recognition of the important contributions made at numerous other laboratories, especially those at The Johns Hopkins University, the Massachusetts Institute of Technology and the Bausch & Lomb Optical Company.
Chemical Mechanisms of Semiconductor Nanocrystal Synthesis

Semiconductor nanocrystal quantum dots (QDs) have been the subject of much interest for fundamental and applied studies. The synthesis of QDs has developed over the past 30 years such that production of monodisperse, photostable QDs with a near-exact size and shape are readily achievable. However, an understanding of the chemical reaction mechanism behind the synthesis of QDs has lagged the ability to synthesize high-quality nanoparticles. This review will discuss recent studies of QD synthetic mechanisms that have been proposed for metal-chalcogenide (ME) semiconductor QDs, particularly CdE and PbE. Although the focus here will be on the initial metal–chalcogenide bond formation, we will also discuss growth models for QDs as well as attempt to provide a future outlook for how understanding reaction mechanism can be leveraged to make improved QDs with easily tailored properties.
Advances in glycoprotein synthesis

The development of chemical and enzymatic methods for the synthesis of homogeneous glycoproteins is a fascinating challenge at the interface between chemistry and biology. Discussed here are the currently available methods for preparation of homogeneous glycoproteins. These methods include (1) glycopeptide ligation; (2) glycoprotein remodeling; and (3) in vivo suppressor tRNA technology.
FERMI-LAT OBSERVATIONS AND A BROADBAND STUDY OF SUPERNOVA REMNANT CTB 109

CTB 109 (G109.1-1.0) is a Galactic supernova remnant (SNR) with a hemispherical shell morphology in X-rays and in the radio band. In this work, we report the detection of γ-ray emission coincident with CTB 109, using 37 months of data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. We study the broadband characteristics of the remnant using a model that includes hydrodynamics, efficient cosmic-ray (CR) acceleration, nonthermal emission, and a self-consistent calculation of the X-ray thermal emission. We find that the observations can be successfully fit with two distinct parameter sets, one where the γ-ray emission is produced primarily by leptons accelerated at the SNR forward shock and the other where γ-rays produced by forward shock accelerated CR ions dominate the high-energy emission. Consideration of thermal X-ray emission introduces a novel element to the broadband fitting process, and while it does not rule out either the leptonic or the hadronic scenarios, it constrains the parameter sets required by the model to fit the observations. Moreover, the model that best fits the thermal and nonthermal emission observations is an intermediate case, where both radiation from accelerated electrons and hadrons contribute almost equally to the γ-ray flux observed.
Approximate Self-Assembly of the Sierpinski Triangle

The Tile Assembly Model is a Turing universal model that Winfree introduced in order to study the nanoscale self-assembly of complex DNA crystals. Winfree exhibited a self-assembly that tiles the first quadrant of the Cartesian plane with specially labeled tiles appearing at exactly the positions of points in the Sierpinski triangle. More recently, Lathrop, Lutz, and Summers proved that the Sierpinski triangle cannot self-assemble in the “strict” sense in which tiles are not allowed to appear at positions outside the target structure. Here we investigate the strict self-assembly of sets that approximate the Sierpinski triangle. We show that every set that does strictly self-assemble disagrees with the Sierpinski triangle on a set with fractal dimension at least that of the Sierpinski triangle (≈1.585), and that no subset of the Sierpinski triangle with fractal dimension greater than 1 strictly self-assembles. We show that our bounds are tight, even when restricted to supersets of the Sierpinski triangle, by presenting a strict self-assembly that adds communication fibers to the fractal structure without disturbing it. To verify this strict self-assembly we develop a generalization of the local determinism method of Soloveichik and Winfree.
Theta functions, modular invariance, and strings

We use Quillen's theorem and algebraic geometry to investigate the modular transformation properties of some quantities of interest in string theory. In particular, we show that the spin structure dependence of the chiral Dirac determinant on a Riemann surface is given by Riemann's theta function. We use this result to investigate the modular invariance of multiloop heterotic string amplitudes.
Ergosterol and Stigmasterol Interact with Phosphatidylcholine Lipid Bilayers Less Favorably than Cholesterol

Sterols are a class of membrane lipids that is important to maintain plasma membrane structure and functions in eukaryotic cells. The maximum solubility of sterol in a lipid bilayer is the highest mole fraction of sterol that can be incorporated into a lipid bilayer before sterol precipitates from the bilayer to form crystals. A higher maximum solubility indicates more favorable interactions between the sterol and lipid bilayer. In this study, the maximum solubilities of ergosterol and stigmasterol in DOPC and DSPC lipid bilayers were measured using light scattering and further confirmed using optical microscopy. We found that correlation function of scattering intensities from two independent detectors can be used to sensitively determine the solubility limits of sterols. The validity of our new technique was confirmed by measuring the solubility limit of cholesterol in DOPC and DPPC lipid bilayers. We found that the maximum solubilities of ergosterol and stigmasterol are higher in PC lipid bilayers with saturated chains (DSPC) than that in PC bilayers with unsaturated chains (DOPC). Compared with cholesterol, ergosterol and stigmasterol both have much lower solubility limits in PC lipid bilayers. Our results suggest that minor differences in sterol structure could result in large differences in sterol-PC interactions.
Lensing Probabilities for Spectroscopically Selected Galaxy-Galaxy Strong Lenses

Spectroscopic galaxy-galaxy lens searches are presently the most prolific method of identifying strong lens systems in large data sets. We study the probabilities associated with these lens searches, namely the probability of identifying a candidate with rogue [O II] emission lines in a galaxy's spectrum, and the probability that the candidate will show features of strong lensing in follow-up photometric observations. We include selection effects unique to spectroscopic data, and apply them to the Sloan Lens ACS (SLACS) survey. The most significant selection effect is the finite size of the spectroscopic fiber which selects against large separation lenses and results in a nonmonotonic dependence of the rogue line probability on velocity dispersion. For example, with the 3 -->'' diameter SDSS fiber and 2 -->'' FWHM seeing, we find that the probability that a given LRG has a rogue [O II] line in its spectrum decreases with velocity dispersion from 150 to 300 km s?1 and then increases up to 400 km s?1 for a given source size. The total probability for observing a rogue line in a single survey spectrum is ~0.9%-3.0%, and the total lensing rate is ~0.5%-1.3%. The range is due to uncertainties in the physical size of [O II] emission regions, and in the evolution of the [O II] luminosity function. Our estimates are a factor of ~5 higher than the results of the SLACS survey, a discrepancy which we attribute to the SLACS requirement that multiple rogue lines be observed simultaneously.
Black hole condensation and duality in string theory

The classical, four-dimensional theories derived by Calabi-Yau compactification of string theory bear a striking resemblance to the real world [1]. However, these classical theories are beset by several serious difficulties: 1. There are too many of them. This is aesthetically displeasing because a unified theory should be unique. It also entails a loss of predictive power. 2. The theory breaks down and develops naked singularities at certain “conifold” points in the moduli space of the massless four-dimensional scalar fields [2].
Asymptotic Data Rates of Receive-Diversity Systems with MMSE Estimation and Spatially Correlated Interferers

An asymptotic technique is presented to characterize the data rate (bits/symbol) achievable on a wireless link in a spatially distributed network with active interferers at correlated positions, N receive diversity branches, and linear Minimum-Mean-Square-Error (MMSE) receivers. This framework is then applied to systems including analogs to Matern type I and type II networks which are useful to model systems with Medium-Access Control (MAC), cellular uplinks with orthogonal transmissions and frequency reuse, and Boolean cluster networks. It is found that for our network models, with moderately large N, the correlation between interferer positions does not significantly influence the rate, resulting in simple approximations for the data rates achievable in such networks which are known to be difficult to analyze and for which only a few results are available. These results can help system designers to optimize parameters such as frequency reuse factors in cellular networks and understand the trade off between improved data rates and increased costs associated with increasing diversity orders for a wide range of system models.
Basal cell carcinoma occurring in multiple familial trichoepithelioma: detection of loss of heterozygosity in chromosome 9q.

Basal cell carcinoma (BCC) occasionally arises from the preexisting lesions of multiple familial trichoepithelioma (MFT). 1 The gene for BCC has been assigned to chromosome 9q22.3-q31, 2 and the gene for Bazex-Dupre-Christol syndrome, characterized by the early onset of multiple BCCs, has been mapped to chromosome Xq24-q27.1. 3 Recently, we carried out a linkage analysis in 3 families with MFT and mapped the gene for MFT to chromosome 9p21. 4 Therefore, trichoepithelioma does not seem to be allelic with BCC despite their histological similarities. To assess the involvement of the BCC genes in the development of BCC in MFT lesions, we examined the possibility of loss of heterozygosity in 2 different BCC specimens from the same patient using microsatellite markers of chromosomes 9q22-q31, Xq24-q27, and 9p21. Only the markers of chromosome 9q22-q31, the locus for sporadic BCCs and nevoid BCC syndrome, showed loss of heterozygosity in 1 of the 2
Recovery of p-modes in the combined 2004-2005 MOST observations of Procyon

Aims. Procyon A, a bright F5 IV-V Sun-like star, is justifiably regarded as a prime asteroseismological target. This star was repeatedly observed by MOST, a specialized microsatellite providing long-term, non-interrupted broadband photometry of bright targets. So far, the widely anticipated p-modes eluded direct photometric detection, though numerous independent approaches hinted for the presence of signals in the f ∼ 0.5-1.5 mHz range. Methods. Implementation of an alternative approach in data processing, as well as combination of the MOST data from 2004 and 2005 (264 189 measurements in total) helps to reduce the instrumental noise affecting previous reductions, bringing the 3σ detection limit down to ∼5.5 part-per-million in the f = 0.8-1.2 mHz range. Results. This enabled us to cross-identifiy 16 p-mode frequencies (though not their degrees) which were previously detected via high-precision radial velocity measurements, and provides an estimate of the large spacing, δv = 0.0540 mHz at f ∼ 1 mHz. The relatively low average amplitude of the detected modes, a = 5.8 ± 0.6 ppm, closely matches the amplitudes inferred from the ground-based spectroscopy and upper limits projected from WIRE photometry. This also explains why such low-amplitude signals eluded the direct-detection approach which exclusively relied on the MOST 2004 (or 2005) data processed by a standard pipeline.
Cache-Oblivious Algorithms

This article presents asymptotically optimal algorithms for rectangular matrix transpose, fast Fourier transform (FFT), and sorting on computers with multiple levels of caching. Unlike previous optimal algorithms, these algorithms are cache oblivious: no variables dependent on hardware parameters, such as cache size and cache-line length, need to be tuned to achieve optimality. Nevertheless, these algorithms use an optimal amount of work and move data optimally among multiple levels of cache. For a cache with size M and cache-line length B where M = Ω(B2), the number of cache misses for an m × n matrix transpose is Θ(1 + mn/B). The number of cache misses for either an n-point FFT or the sorting of n numbers is Θ(1 + (n/B)(1 + logM n)). We also give a Θ(mnp)-work algorithm to multiply an m × n matrix by an n × p matrix that incurs Θ(1 + (mn + np + mp)/B + mnp/B√M) cache faults.We introduce an “ideal-cache” model to analyze our algorithms. We prove that an optimal cache-oblivious algorithm designed for two levels of memory is also optimal for multiple levels and that the assumption of optimal replacement in the ideal-cache model can be simulated efficiently by LRU replacement. We offer empirical evidence that cache-oblivious algorithms perform well in practice.
Nontangent, Developed Contour Bulkheads for a Single-Stage Launch Vehicle

Dry weights for single-stage launch vehicles that incorporate nontangent, developed contour bulkheads are estimated and compared to a baseline vehicle with 1.414 aspect ratio ellipsoidal bulkheads. Weights, volumes, and heights of optimized bulkhead designs are computed using a preliminary design bulkhead analysis code. The dry weights of vehicles that incorporate the optimized bulkheads are predicted using a vehicle weights and sizing code. Two optimization approaches are employed. A structural-level method, where the vehicle's three major bulkhead regions are optimized separately and then incorporated into a model for computation of the vehicle dry weight, predicts a reduction of4365 lb (2.2 %) from the 200,679-lb baseline vehicle dry weight. In the second, vehicle-level, approach, the vehicle dry weight is the objective function for the optimization. For the vehicle-level analysis, modified bulkhead designs are analyzed and incorporated into the weights model for computation of a dry weight. The optimizer simultaneously manipulates design variables for all three bulkheads to reduce the dry weight. The vehicle-level analysis predicts a dry weight reduction of 5129 lb, a 2.6% reduction from the baseline weight. Based on these results, nontangent, developed contour bulkheads may provide substantial weight savings for single stage vehicles.
Reconstruction of ECG signals in presence of corruption

We present an approach to identifying and reconstructing corrupted regions in a multi-parameter physiological signal. The method, which uses information in correlated signals, is specifically designed to preserve clinically significant aspects of the signals. We use template matching to jointly segment the multi-parameter signal, morphological dissimilarity to estimate the quality of the signal segment, similarity search using features on a database of templates to find the closest match, and time-warping to reconstruct the corrupted segment with the matching template. In experiments carried out on the MIT-BIH Arrhythmia Database, a two-parameter database with many clinically significant arrhythmias, our method improved the classification accuracy of the beat type by more than 7 times on a signal corrupted with white Gaussian noise, and increased the similarity to the original signal, as measured by the normalized residual distance, by more than 2.5 times.
A New Instrument for Time-Resolved Reduction of Scattered Radiation in Fluorescence Measurements.

Abstract An opto-electronic cross-correlation system was employed to reduce the scattering influence in fluorescence measurements. A stable optical delay line incorporated into the instrument was positioned to yield detection at a fixed time after excitation; the optimal delay time was determined simply from the ratio of the fluorescence decay curve to a similar curve portraying scattering response. Signal-to-scattering background enhancements greater than two were measured for the very short-lived (τ = 0.7 ns) fluorophores whereas a six-fold increase was measured for fluorophores with longer lifetimes. The shortest lifetime which would benefit from time-resolution in this system is limited by the time-response of the photomultiplier tube (1.1 ns FWHM); the excitation pulses are on the order of 6 ps.
AMBLYOPIA: A HIDDEN THREAT?*

SUMMARY Patricia and Ronald M. Deutsch (1965) recently attempted to develop the thesis that “A shocking number of children face partial blindness if their defective vision is not caught early and corrected.” And further, that, “Today, volunteer housewives in scores of communities are showing how this threat can be overcome.” The major arguments offered by the Deutschs to support their thesis are shown herein to be based on erroneous facts and misleading statements. Their thesis is therefore unacceptable, and the following statements are made to correct the misinformation contained in their article. (a) For American children, the probable incidence of amblyopia (20/40 or worse acuity with best optical correction) is in the neighborhood of 1.0 to 1.5% (b) There is no critical age for the successful treatment of amblyopia, although there may be some advantage for treatment at an early age. The treatment of amblyopia is not hopeless after the ages of 6 to 8 years, as is often stated. (c) Amblyopia produces little if any handicap in most visual situations. The problem in amblyopia is more potential than existing–namely, loss of the better eye. (d) The pre-school vision screening program for lay volunteers, recommended by the National Society for the Prevention of Blindness, is not designed to detect mainly amblyopia, but rather to uncover many ordinary vision problems. The crucial question is not whether volunteer housewives have demonstrated how the “threat” of amblyopia can be overcome by screening pre-schoolers, but to what extent is amblyopia a “threat” when discovered after children enter grade school?
Slant-path scintillation in the planetary boundary layer.

Results are presented from an experimental study of the effects of range, path geometry, and thermal turbulence intensity in the planetary boundary layer on the laser scintillation magnitude, represented by the log-intensity standard deviation σ. Intensity fluctuations of two 15-mW helium–neon laser beams propagating along reciprocal slant paths were measured simultaneously for a path elevation of 460 m and horizontal ranges from 0.6 km to 10 km, during both daytime and nighttime periods. Vertical profiles of the refractive-index-structure function Cn were obtained concurrently along with conventional wind and temperature profiles. It was observed that the range and turbulence dependence of σ differs significantly under inversion and lapse atmospheric conditions. When the scintillation predicted by the classical theory of Tatarski (σt) is used as a scale factor, the observed scintillation (σm) values occur at σt−-values that are about a factor of 2 larger for lapse conditions than for the inversion cases. This may reflect a dependence of the scintillation pattern on the frequency (or scale) of thermal turbulence fluctuations (represented by Cn), in addition to the well-known intensity dependence. The value of σm at saturation is slightly larger for the ground-to-air path (σm ≈ 1.7) than for the air-to-ground path (σm ≈ 1.4). Comparisons are made of the ratio of the sigma values along the two paths as a function of range and turbulence intensity; the observed ratios are poorly described by the existing theory.
The IMF And Concerted Lending In Latin-American Debt Restructurings: A Formal Analysis

Abstract This paper models the IMF's policy of making its participation in an adjustment program contingent on a commitment by banks to finance the associated debt restructuring. The analysis shows that this tactic pressures smaller banks, tempted not to participate in sovereign debt restructurings, to participate. However, it is also shown that the bank participation rate falls as required new lending rises. Furthermore, the incentive for banks to choose not to participate rises as the probability of a future default rises and as bank capital increases.