cssi/SciSciGPT-SciSciNet huggingface dataset:
Determination of long distance intramolecular triplet energy transfer rates. A quantitative comparison with electron transfer

Recent efforts in these laboratories have been directed toward understanding the factors governing long distance intramolecular electron transfer (ET). In the models chosen for study the electronic coupling between donor and acceptor is sufficiently weak to assure nonadiabatic reactions. It occurred to them that long distance triplet energy transfer by the Dexter mechanism (TT) of which there are several examples in the literature should exhibit features similar to nonadiabatic electron transfer because both reactions are governed by the same theory of radiationless transitions. They therefore have started a program aimed at finding quantitative similarities and differences in these two processes when studied on directly comparable systems. Also, with one exception, the absolute rates of intramolecular triplet energy transfer have never been measured directly in liquid solution. In this communication they report their first results and conclusions.
Electrochemical reduction of thermally prepared oxides of iron and iron-chromium alloys studied by in situ Raman spectroscopy

Pure Fe and Fe/Cr alloys (3% and 12% Cr) were oxidized at 250–260°C and subsequently electrochemically reduced in borate buffer, pH 8.4. The reduction was followed by in situ Raman spectroscopy as well as chronopotentiometric and chronoamperometric measurements. At several time intervals ex situ Raman control investigations and ESCA analyses were undertaken. Although at −0.7 V vs sce partial reduction of the oxide film was observed, α-Fe2O3 remained unchanged and reduced at −0.9 V. A mixture of spinel structured oxide, possibly Fe3O4, and a ferrous deposit were observed when the oxide film was galvanostatically reduced at 100 μA cm−2; after prolonged reduction the bare metal resulted. The thermally created oxide of the Cr alloy possessed an inner Cr rich layer which during the galvanostatic reduction of the oxide film at 50 μA cm−2 is most likely responsible for an increase in the overpotential of more than 80 mV.
Deformation Texture and Magnetic Properties of BaO·6Fe2O3

Compressive deformation of isotropic and magnetically wetoriented stoichiometric BaO-6Fe2O3 was studied in creep and press forging modes in the temperature range 1000° to 1200°C at stresses to 6000 psi. Texture development was followed by electron microscopy and measured quantitatively by X-ray diffraction. Magnetic properties of the deformation-textured materials were correlated with changes in texture and grain morphology.
Mix and match

Consider a matching problem on a graph where disjoint sets of vertices are privately owned by self-interested agents. An edge between a pair of vertices indicates compatibility and allows the vertices to match. We seek a mechanism to maximize the number of matches despite self-interest, with agents that each want to maximize the number of their own vertices that match. Each agent can choose to hide some of its vertices, and then privately match the hidden vertices with any of its own vertices that go unmatched by the mechanism. A prominent application of this model is to kidney exchange, where agents correspond to hospitals and vertices to donor-patient pairs. Here hospitals may game an exchange by holding back pairs and harm social welfare.In this paper we seek to design mechanisms that are strategyproof, in the sense that agents cannot benefit from hiding vertices, and approximately maximize efficiency, i.e., produce a matching that is close in cardinality to the maximum cardinality matching. Our main result is the design and analysis of the eponymous Mix-and-Match mechanism; we show that this randomized mechanism is strategyproof and provides a 2-approximation. Lower bounds establish that the mechanism is near optimal.
Metallicity-corrected Tip of the Red Giant Branch Distance to NGC 4258

We have determined the distance to NGC 4258 using observations made with the Hubble Space Telescope (HST) and the Wide Field, Advanced Camera for Surveys (ACS WFC). We apply a modified technique that fully accounts for metallicity effects on the use of the luminosity of the tip of the red giant branch (TRGB) to determine one of the most precise TRGB distance moduli to date, μ (TRGB) = 29.28 ± 0.04 (random) ± 0.12 (systematic) mag (7.18 ± 0.13 ± 0.40 Mpc). We discuss this distance modulus with respect to other recent applications of the TRGB method to NGC 4258 and with several other techniques (Cepheids and masers) that are equally competitive in their precision, but different in their systematics.
Congenital leukemia presenting as fever in a neonate.

Abstract Background Emergency department workup of pediatric fever typically focuses on ruling out serious bacterial infection, but other disease processes can cause fever. Congenital leukemia is a rare but important cause of fever in neonates. We review the presentation, pathophysiology, and potential complications of congenital leukemia presenting to the emergency department as pediatric fever. Case Report We report a case of a 4-week-old infant brought to the emergency department for fever and “not acting normally.” Complete blood count demonstrated hyperleukocytosis. Subsequent bone marrow biopsy and flow cytometry confirmed the diagnosis of congenital leukemia. The extreme elevation of the patient's white blood cell count put her at high risk for complications, necessitating aggressive treatment, close monitoring, and appropriate consultation for comprehensive care. Why Should an Emergency Physician Be Aware of This Congenital leukemia is a rare but serious cause of neonatal fever. While the workup for fever without a source in young pediatric patients primarily focuses on ruling out serious bacterial illness, emergency physicians must be familiar with other potentially life-threatening causes of this complaint.
Quantum knots and mosaics

In this paper, we give a precise and workable definition of a quantum knot system, the states of which are called quantum knots. This definition can be viewed as a blueprint for the construction of an actual physical quantum system. Moreover, this definition of a quantum knot system is intended to represent the "quantum embodiment" of a closed knotted physical piece of rope. A quantum knot, as a state of this system, represents the state of such a knotted closed piece of rope, i.e., the particular spatial configuration of the knot tied in the rope. Associated with a quantum knot system is a group of unitary transformations, called the ambient group, which represents all possible ways of moving the rope around (without cutting the rope, and without letting the rope pass through itself.) Of course, unlike a classical closed piece of rope, a quantum knot can exhibit non-classical behavior, such as quantum superposition and quantum entanglement. This raises some interesting and puzzling questions about the relation between topological and quantum entanglement. The knot type of a quantum knot is simply the orbit of the quantum knot under the action of the ambient group. We investigate quantum observables which are invariants of quantum knot type. We also study the Hamiltonians associated with the generators of the ambient group, and briefly look at the quantum tunneling of overcrossings into undercrossings. A basic building block in this paper is a mosaic system which is a formal (rewriting) system of symbol strings. We conjecture that this formal system fully captures in an axiomatic way all of the properties of tame knot theory.
Workshop on high resolution electron microscopy

Summary Following presentations by invited speakers, the workshop participants divided into six groups in order to concentrate on the following aspects of HREM: 1) HREM in materials science, 2) HREM in mineralogy and solid state chemistry, 3) Image interpretation, 4) Microanalysis and microdiffraction, 5) Radiation damage, 6) Instrumentation. Both presentations and discussions during the workshop emphasized that high resolution electron microscopy has already incited a revolution in crystal structure analysis. At optimum working levels, current 100 kV microscopes are revealing interpretable details of atomic arrangements at 3 to 4 A resolution. Particularly for mineralogists and solid state chemists, this capability is extremely useful. Nevertheless scientists are prevented from applying high resolution analytical methods to those materials having the greatest commercial importance, i.e., metallic and ceramic alloys. In these structures, interatomic separations of ≲2 A are most common, requiring an improvement in resolution by a factor of 2 relative to present instruments. As revealed during the workshop, overcoming this resolution barrier will require the use of higher accelerating voltages which decrease the electron wavelength. Such high voltage, high resolution microscopes are now being built in Europe and Japan, and a 500 kV machine is currently in operation at the University of Kyoto. It therefore appears likely that the resolution limit for interpretable images of crystals will soon be reduced to about 1.5 A. The benefits of higher voltage fortunately extend beyond enhanced resolution. At 500 kV, specimens may be 3 to 4 times thicker than required for 100 kV operation, and image contrast for individual atoms or atomic defects in crystals will be improved by a factor of 2 or 3. In addition, raising the accelerating voltage from 100 kV to 500 kV results in a reduction of bond-breaking damage due to inelastic scattering (a factor of 4). This will permit high resolution imaging of many beam-sensitive materials, including polymers, ionic crystals and biological specimens.
Design and performance of tree-structured vector quantizers

Abstract The design of vector quantizers (VQ) involves the partitioning of a multidimensional space into a finite number of regions. It is desired but generally difficult to find the partition that minimizes the expected distortion subject to a cost constraint. Tree-structured vector quantization (TSVQ) reduces the complexity by imposing a hierarchical structure on the partitioning. We study the design of optimal tree-structured vector quantizers that minimize the expected distortion subject to cost functions related to storage cost, encoding rate, or quantization time. The optimal design problem is shown to be intractable in most cases, and heuristic techniques have to be used. We analyze the performance of a general design heuristic based on successive partitioning, and propose a recursively descend optimization criterion for the algorithm. Experimental results in image compression show the new criterion performs favorably compared with existing ones.
Nonuniqueness of strained ascent shapes of high altitude balloons

Abstract A feature characterizing partially inflated scientific balloons is a lobed structure surrounding the gas bubble. We present a mathematical model for such a balloon shape. We formulate a variational principal for the balloon, and seek to determine shapes that minimize its total energy subject to a volume constraint. The energy includes contributions due to film and load tendon strain, film and load tendon weight, and hydrostatic pressure. Wrinkling of the film is modeled via energy relaxation. We investigate the plausibility of a minimum energy selection principle for strained wrinkled balloon shapes with lobes. We find multiple solutions for the same set of conditions, demonstrating nonuniqueness. In solution space, these equilibrium configurations are local minimizers. The means by which a particular lobe pattern is “selected” in a real ascending balloon is dependent on a number of factors, some of which may be indeterminate (e.g., the distribution of the excess balloon material below the gas bubble). Nevertheless, with our approach, we are able to calculate partially inflated balloon equilibrium shapes that have many features of real ascent shapes, and, as a by-product of our solution process, we are able to obtain estimates of the film stress resultants.
Toward a Self-Consistent Model of the Ionized Absorber in NGC 3783

We present a detailed model for the ionized absorbing gas evident in the 900 ks Chandra HETGS spectrum of NGC 3783. The analysis was carried out with PHASE, a new tool designed to model X-ray and UV absorption features in ionized plasmas. The 0.5-10 keV intrinsic continuum of the source is well represented by a single power law (Γ = 1.53) and a soft blackbody component (kT ~ 0.1 keV). The spectrum contains over 100 features, which are well fitted by PHASE with just six free parameters. The model consists of a simple two-phase absorber with a difference of ≈35 in the ionization parameter and a difference of ≈4 in the column density of the phases. The two absorption components turned out to be in pressure equilibrium and are consistent with a single outflow (≈750 km s-1), a single turbulent velocity (300 km s-1), and solar elemental abundances. The main features of the low-ionization phase are an Fe M-shell unresolved transition array (UTA) and the O VII lines. The O VII features, usually identified with the O VIII and a warm absorber, are instead produced in a cooler medium that also produces O VI lines. The UTA sets tight constraints on the ionization degree of the absorbers, making the model more reliable. The high-ionization phase is required by the O VIII and the Fe L-shell lines, and there is evidence for an even more ionized component in the spectrum. A continuous range of ionization parameters is disfavored by the fits, particularly to the UTA. Our model indicates a severe blending of the absorption and emission lines, as well as strong saturation of the most intense O absorption lines. This is in agreement with the O VII (τλ = 0.33) and O VIII (τλ = 0.13) absorption edges required to fit the spectrum. The low-ionization phase can be decomposed into three subcomponents on the basis of the outflow velocity, FWHM, and H column densities found for three of the four UV absorbers detected in NGC 3783. However, the ionization parameters are systematically smaller in our model than those derived from UV data, indicating a lower degree of ionization. Finally, our model predicts a Ca XVI line for the feature observed at around 21.6 A (a feature formerly identified as O VII), constraining the contribution from a zero-redshift absorber.
Efficient resource management for linear logic proof search

The design of linear logic programming languages and theorem provers opens a number of new implementation challenges not present in more traditional logic languages such as Horn clauses (Prolog) and hereditary Harrop formulas (λProlog and Elf). Among these, the problem of efficiently managing the linear context when solving a goal is of crucial importance for the use of these systems in non-trivial applications. This paper studies this problem in the case of Lolli [10], though its results have application to other systems including those based on linear type theory. We first give a proof-theoretic presentation of the operational semantics of this language as a resolution calculus. We then present a series of resource management systems designed to eliminate the non-determinism in the distribution of linear formulas that undermines the efficiency of a direct implementation of this system.
The free cash flow hypothesis for sales growth and firm performance

business is business! And business must grow –Dr. Seuss, The Lorax The paper investigates the agency argument that sales growth in firms with free cash flow (and without strong governance) is less profitable than sales growth for firms without free cash flow. It also tests whether strong governance conditions improve the performance of firms with free cash flow and/or limit the investments in unprofitable sales growth. Consistent with agency theory, firms with free cash flow gain less from sales growth than firms without free cash flow. But different governance conditions affect sales growth and performance in different ways. Having substantial management stock ownership mitigates the influence of free cash flow on performance, despite allowing higher sales growth. In contrast, outside blocks held by mutual funds reduce sales growth substantially, but does not increase performance from sales growth. Copyright © 2000 John Wiley & Sons, Ltd.
Hydrodynamic Interaction of Strong Shocks with Inhomogeneous Media. I. Adiabatic Case

Many astrophysical flows occur in inhomogeneous (clumpy) media. We present results of a numerical study of steady, planar shocks interacting with a system of embedded cylindrical clouds. Our study uses a two-dimensional geometry. Our numerical code uses an adaptive mesh refinement, allowing us to achieve sufficiently high resolution both at the largest and the smallest scales. We neglect any radiative losses, heat conduction, and gravitational forces. Detailed analysis of the simulations shows that interaction of embedded inhomogeneities with the shock/postshock wind depends primarily on the thickness of the cloud layer and arrangement of the clouds in the layer. The total cloud mass and the total number of individual clouds is not a significant factor. We define two classes of cloud distributions: thin and thick layers. We define the critical cloud separation along the direction of the flow and perpendicular to it, distinguishing between the interacting and noninteracting regimes of cloud evolution. Finally, we discuss mass loading and mixing in such systems.
The flavor of a little Higgs with T-parity

We analyze flavor constraints in the littlest Higgs model with T-parity. In particular, we focus on neutral meson mixing in the K, B, and D systems due to one loop contributions from T-parity odd fermions and gauge bosons. We calculate the short distance contributions to mixing for a general choice of T-odd fermion Yukawa couplings. We find that for a generic choice of textures, a TeV scale GIM suppression is necessary to avoid large contributions. If order one mixing angles are allowed in the extended flavor structure, the mass spectrum is severely constrained, and must be degenerate at the 1-5% level. However, there are still regions of parameter space where only a loose degeneracy is necessary to avoid constraints. We also consider the B(s) system, and identify a scenario in which the mixing can be significantly enhanced beyond the standard model prediction while still satisfying bounds on the other mixing observables. We present both analytical and numerical results as functions of the T-odd fermion mass eigenvalues.
Heralded single-magnon quantum memory for photon polarization States.

We demonstrate a heralded quantum memory where a photon announces the mapping of a light polarization state onto a single collective-spin excitation (magnon) shared between two atomic ensembles. The magnon can be converted at a later time into a single polarized photon with polarization fidelity over 90(2)% for all fiducial input states, well above the classical limit of $\frac{2}{3}$. The process can be viewed as a nondestructive quantum probe where a photon is detected, stored, and regenerated without touching its---potentially undetermined---polarization.
Synthesis and spectroscopic properties of N,N-bridged dipyrrinones

Abstract 3,4-Dimethylpyrrole-2-aldehyde was converted into methano (1), ethano (2) and 1,3-propano N10,N11-bridged dipyrrinones. At room temperature in cyclohexane the large fluorescence quantum yield associated with 1 (φF⋍0.81) falls off significantly with increasing bridge length (2: φF = 0.26, 3: φF = 0.0012).
Synthesis and Equation of State of (Mg,Fe) SiO3 Perovskite to Over 100 Gigapascals.

Silicate perovskite of composition (Mg0.88Fe0.12) SiO3 has been synthesized in a laser-heated diamond-anvil cell to a pressure of 127 gigapascals at temperatures exceeding 2000 K. The perovskite phase was identified and its unit-cell dimensions measured by in situ x-ray diffraction at elevated pressure and room temperature. An analysis of these data yields the first high-precision equation of state for this mineral, with values of the zero-pressure isothermal bulk modulus and its pressure derivative being K0T = 266 ± 6 gigapascals and K90T = 3.9 ± 0.4. In addition, the orthorhombic distortion of the silicate-perovskite structure away from ideal cubic symmetry remains constant with pressure: the lattice parameter ratios are b/a = 1.032 ± 0.002 and c/a = 1.444 ± 0.006. These results, which prove that silicate perovskite is stable to ultrahigh pressures, demonstrate that perovskite can exist throughout the pressure range of the lower mantle and that it is therefore likely to be the most abundant mineral in Earth.
Highly diastereoselective synthesis of modified nucleosides via an asymmetric multicomponent reaction

We have developed a practical synthesis of unique nucleoside derivatives via TiCl4 promoted multicomponent reaction of optically active dihydrofuran, ethyl pyruvate/glyoxylate, and a TMS protected nucleobase in a single-pot operation.
A case-controlled study of 18-fluorodeoxyglucose positron emission tomography in the detection of pelvic recurrence in previously irradiated rectal cancer patients.

Abstract Background Although effective at detecting locally recurrent colorectal cancer, the accuracy of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) for detecting rectal cancer recurrence in an irradiated pelvis has not been systematically studied. Study design Records of surgically resected rectal cancer patients who underwent FDG-PET imaging at least 6 months after external beam radiation therapy (EBRT) were reviewed. Cases (n = 19) were defined as scans from patients in whom a pelvic recurrence was confirmed (histologically, n=14, radiologic followup, n=5). Controls (n = 41), defined as scans from patients without clinical or radiologic evidence of pelvic recurrence, were compared with cases for the time interval between completion of EBRT and FDG-PET imaging (RT/PET interval, mean 25.1 months versus 27.5 months, respectively), as well as EBRT dose (mean 5,084 cGy versus 5,062 cGy, respectively). All 60 FDG-PET scans were iteratively reconstructed and reinterpreted by a single nuclear medicine physician blinded to original FDG-PET interpretation and disease status. Certainty of disease was scored on a five-point scale (1 to 5), with scores greater than or equal to 4 considered positive. Results FDG-PET correctly identified 16 of 19 recurrences, for a sensitivity of 84% and specificity of 88%. Overall accuracy was 87%. Positive predictive value was 76% and negative predictive value was 92%. Positive predictive value and accuracy improved in scans performed more than 12 months after EBRT. Conclusions Our preliminary data suggest that FDG-PET is an accurate modality for detecting pelvic recurrence of rectal cancer after full-dose EBRT. Its reliability appears to improve with time, perhaps because of resolution of early postradiation inflammation.
User Arrival in MIMO Interference Alignment Networks

In this paper we analyze a constant multiple-input multiple-output interference channel where a set of active users are cooperating through interference alignment while a set of secondary users desire access to the channel. We find the minimum number of secondary transmit antennas required so that a secondary user can use the channel without affecting the sum rate of the active users, under a zero-forcing equalization assumption. When the secondary users have enough antennas, we derive several secondary user precoders that approximately maximize the secondary users' sum rate without changing the sum rate of the active users. When the secondary users do not have enough antennas, we perform numerical optimization to find secondary user precoders that cause minimum degradation to the sum rate of the active users. Through simulations, we confirm that i) with enough antennas at the secondary users, gains equivalent to the case of all the users cooperating through interference alignment is obtainable, and ii) when the secondary users do not have enough antennas, large rate losses at the active users can be avoided.channels
Majorana end states in multiband microstructures with Rashba spin-orbit coupling

A recent work [Potter and Lee, Phys. Rev. Lett. 105, 227003 (2010)] demonstrated, for an ideal spinless $p+\mathit{ip}$ superconductor, that Majorana end states can be realized outside the strict one-dimensional limit, so long as (1) the sample width does not greatly exceed the superconducting coherence length and (2) an odd number of transverse subbands are occupied. Here we extend this analysis to the case of an effective $p+\mathit{ip}$ superconductor engineered from a Rashba spin-orbit-coupled surface with induced magnetization and superconductivity, and find a number of additional features. Specifically, we find that finite-size quantization allows Majorana end states even when the chemical potential is outside of the induced Zeeman gap where the bulk material would not be topological. This is relevant to proposals utilizing semiconducting quantum wires; however, we also find that the bulk energy gap is substantially reduced if the induced magnetization is too large. We next consider a slightly different geometry, and show that Majorana end states can be created at the ends of ferromagnetic domains. Finally, we consider the case of meandering edges and find, surprisingly, that the existence of well-defined transverse subbands is not necessary for the formation of robust Majorana end states.
Asymptotically Optimal Anomaly Detection via Sequential Testing

Sequential detection of independent anomalous processes among $K$ processes is considered. At each time, only $M$ $(1\leq M\leq K)$ processes can be observed, and the observations from each chosen process follow two different distributions, depending on whether the process is normal or abnormal. Each anomalous process incurs a cost per unit time until its anomaly is identified and fixed. Switching across processes and state declarations are allowed at all times, while decisions are based on all past observations and actions. The objective is a sequential search strategy that minimizes the total expected cost incurred by all the processes during the detection process under reliability constraints. We develop index-type algorithms for the case with both known observation distributions and the case when the observation distributions have unknown parameters. We show that the proposed algorithms are asymptotically optimal in terms of minimizing the total expected cost as the error constraints approach zero. Simulation results demonstrate strong performance in the finite regime.
A comparison of destabilization mechanisms of the layered NaxMO2 and LixMO2 compounds upon alkali de-intercalation

To understand the difference in reversible energy storage capacity between the O3-type layered Na and Li compounds, we use first principles calculations to study and contrast the effect of two well-known destabilization mechanisms, transformation into the spinel-type structures and cation mixing due to transition metal migration. This study is performed on the layered oxides at the A0.5MO2 composition, where A = (Na, Li) and M is a 3d transition metal. We find that while all Li0.5MO2 compounds have strong driving forces and low energy kinetic paths to transform to the spinel structure, Na0.5MO2 compounds do not have thermodynamic driving forces to transform to spinel type structures. We also find that transition metal mobility is higher in Li layered compounds than in Na layered compounds because of the unusual activated state for transition metal hopping. For many compounds, migration goes along an oct–tet–oct path, but transition metal migration needs to be assisted by alkali migration into a tetrahedral site forming activated Atet–Mtet defects; substituting Na for Li in the layered structure results in increased transition metal migration barriers due to the larger size of Na+ ions. Overall, our findings indicate that Na compounds in the layered O3 structure have fundamentally different destabilization mechanisms to those of Li compounds. This distinction allows superior battery electrode performance in many Na compounds and offers optimistic perspective on finding many high energy density Na electrodes that cycle with stable high capacity.
CONFORMALITY AND COMPOSITION OF FILMS DEPOSITED AT LOW PRESSURES

Conformality limitations and film composition variations inside features for films deposited at low pressures are explained using examples of studies which combine transport and reaction simulations of deposition processes and carefully designed experimental work. In the first example, the use of film profile information to decide between two kinetic models for the deposition of SiO2 from TEOS is described. In the second example, composition profiles in sputter deposited Ti-W are explained in terms of titanium re-emission. Combined simulation and experimental studies of film profiles and composition profiles in features is a valuable tool in efforts to arrive at useful kinetic and transport models.
Dynamic and static components power unfolding in topologically closed rings of a AAA+ proteolytic machine.

A biochemical study reveals the AAA+ protein unfoldase ClpX functions as a closed ring and identifies regions required for intersubunit coupling during the ATPase cycle. These findings provide important insights on the ClpX mechanism that may be extended to other AAA+ proteins. In the Escherichia coli ClpXP protease, a hexameric ClpX ring couples ATP binding and hydrolysis to mechanical protein unfolding and translocation into the ClpP degradation chamber. Rigid-body packing between the small AAA+ domain of each ClpX subunit and the large AAA+ domain of its neighbor stabilizes the hexamer. By connecting the parts of each rigid-body unit with disulfide bonds or linkers, we created covalently closed rings that retained robust activity. A single-residue insertion in the hinge that connects the large and small AAA+ domains and forms part of the nucleotide-binding site uncoupled ATP hydrolysis from productive unfolding. We propose that ATP hydrolysis drives changes in the conformation of one hinge and its flanking domains and that the changes are propagated around the AAA+ ring through the topologically constrained set of rigid-body units and hinges to produce coupled ring motions that power substrate unfolding.
Gauge theory, topological strings, and S-duality

We offer a derivation of the duality between the topological U(1) gauge theory on a Calabi-Yau 3-fold and the topological A-model on the same manifold. This duality was conjectured recently by Iqbal, Nekrasov, Okounkov, and Vafa. We deduce it from the S-duality of the IIB superstring. We also argue that the mirror version of this duality relates the topological B-model on a Calabi-Yau 3-fold and a topological sector of the Type IIA Little String Theory on the same manifold.
Scalable Triadic Analysis of Large-Scale Graphs: Multi-core vs. Multi-processor vs. Multi-threaded Shared Memory Architectures

Triadic analysis encompasses a useful set of graph mining methods that are centered on the concept of a triad, which is a sub graph of three nodes. Such methods are often applied in the social sciences as well as many other diverse fields. Triadic methods commonly operate on a triad census that counts the number of triads of every possible edge configuration in a graph. Like other graph algorithms, triadic census algorithms do not scale well when graphs reach tens of millions to billions of nodes. To enable the triadic analysis of large-scale graphs, we developed and optimized a triad census algorithm to efficiently execute on shared memory architectures. We then conducted performance evaluations of the parallel triad census algorithm on three specific systems: CrayXMT, HP Superdome, and AMD multi-core NUMA machine. These three systems have shared memory architectures but with markedly different hardware capabilities to manage parallelism.
The Energy dependence of the saturation momentum

Abstract We study BFKL evolution and, in particular, the energy dependence of the saturation momentum in the presence of saturation boundaries limiting the region of linear BFKL evolution. In the case of fixed coupling evolution we confirm the previously found exponential term in Q s ( Y ) and determine the prefactor Y and α dependences. In the running coupling case we find Y 1/6 corrections to the Y 1/2 exponential behavior previously known. Geometrical scaling of the scattering amplitude is valid in a wide range of momenta for fixed coupling evolution and in a more restricted region for running coupling evolution.
Minimum Core Masses for Giant Planet Formation with Realistic Equations of State and Opacities

Giant planet formation by core accretion requires a core that is sufficiently massive to trigger runaway gas accretion in less than the typical lifetime of protoplanetary disks. We explore how the minimum required core mass, M crit, depends on a non-ideal equation of state (EOS) and on opacity changes due to grain growth across a range of stellocentric distances from 5-100 AU. This minimum M crit applies when planetesimal accretion does not substantially heat the atmosphere. Compared to an ideal gas polytrope, the inclusion of molecular hydrogen (H2) dissociation and variable occupation of H2 rotational states increases M crit. Specifically, M crit increases by a factor of ~2 if the H2 spin isomers, ortho- and parahydrogen, are in thermal equilibrium, and by a factor of ~2-4 if the ortho-to-para ratio is fixed at 3:1. Lower opacities due to grain growth reduce M crit. For a standard disk model around a Solar mass star, we calculate M crit ~ 8 M ⊕ at 5 AU, decreasing to ~5 M ⊕ at 100 AU, for a realistic EOS with an equilibrium ortho-to-para ratio and for grain growth to centimeter-sizes. If grain coagulation is taken into account, M crit may further reduce by up to one order of magnitude. These results for the minimum critical core mass are useful for the interpretation of surveys that find exoplanets at a range of orbital distances.
MOS technology : Trends and challenges in the ULSI era

This paper reviews the trends in the MOS technology as we approach the turn of the century, and addresses the challenges that we face as the device geometries continue to scale and as the need to lower power dissipation grows, albeit with the demand for increasing device performance.
An iodoetherification–dehydroiodination strategy for the synthesis of complex spiroketals from dihydroxyalkene precursors

Dihydroxyalkenes or their monoprotected alcohol derivatives are transformed to 5,5- and 5,6-spiroketals through a sequence involving an initial iodocyclization, followed by a silver triflate mediated spiroketalization step on the derived hydroxy-iodoether.
Redshifts and Luminosities for 112 Gamma-Ray Bursts

Two different luminosity indicators have recently been proposed for gamma-ray bursts that use gamma-ray observations alone. They relate the burst luminosity (L) with the time lag between peaks in hard and soft energies (τlag) and the spikiness or variability of the burst's light curve (V). These relations are currently justified and calibrated with only six or seven bursts with known redshifts. We have examined BATSE data for τlag and V for 112 bursts. (1) A strong correlation between τlag and V exists, and it is exactly as predicted from the two proposed relations. This is proof that both luminosity indicators are reliable. (2) GRB 830801 is the all-time brightest burst, yet with a small V and a large τlag, and hence it is likely the closest known event, being perhaps as close as 3.2 Mpc. (3) We have combined the luminosities as derived from both indicators as a means to improve the statistical and systematic accuracy when compared with the accuracy from either method alone. The result is a list of 112 bursts with good luminosities and hence redshifts. (4) The burst-averaged hardness ratio rises strongly with the luminosity of the burst. (5) The burst luminosity function is a broken power law, with the break at L = 2 × 1052 ergs. The numbers in logarithmic bins scale as L-2.8±0.2 above the break and as L-1.7±0.1 below the break. (6) The comoving number density of GRBs varies with redshift roughly as (1 + z)3.5±0.3 between 0.2 < z < 5. This demonstrates that the burst rate follows the star formation rate at low redshifts, as expected since long bursts are generated by very massive stars. Excitingly, this result also provides a measure of the star formation rate out to z ~ 5 with no effects from reddening, and the rate is rising uniformly for redshifts above 2.
Highly Ionized High-Velocity Clouds: Intergalactic Gas in the Local Group or Distant Gas in the Galactic Halo?

In the course of our studies of the gaseous halo surrounding the Milky Way, we have recently identified several high-velocity clouds (HVCs; VLSR -1 are favored if the clouds are located in the distant Galactic halo since the cloud sizes scale inversely with metallicity. We provide a summary of the HVCs detected in absorption at intermediate resolution with the GHRS and the IUE satellite and find that C IV HVCs are detected along three of 10 extragalactic sight lines down to a level of logN(C IV)≈13.3 (3σ).
Polynomial complexity of polar codes for non-binary alphabets, key agreement and Slepian-Wolf coding

We consider polar codes for memoryless sources with side information and show that the blocklength, construction, encoding and decoding complexities are bounded by a polynomial of the reciprocal of the gap between the compression rate and the conditional entropy. This extends the recent results of Guruswami and Xia to a slightly more general setting, which in turn can be applied to (1) sources with non-binary alphabets, (2) key generation for discrete and Gaussian sources, and (3) Slepian-Wolf coding and multiple accessing. In each of these cases, the complexity scaling with respect to the number of users is also controlled. In particular, we construct coding schemes for these multi-user information theory problems which achieve optimal rates with an overall polynomial complexity.
Reliability of large superconducting magnets through design

As superconducting magnet systems grow larger and become the central component of major systems involving fusion, magnetohydrodynamics, and high-energy physics, their reliability must be commensurate with the enormous capital investment in the projects. Although the magnet may represent only 15% of the cost of a large system such as the Mirror Fusion Test Facility, its failure would be catastrophic to the entire investment. Effective quality control during construction is one method of ensuring success. However, if the design is unforgiving, even an inordinate amount of effort expended on quality control may be inadequate. Creative design is the most effective way of ensuring magnet reliability and providing a reasonable limit on the amount of quality control needed. For example, by subjecting the last drawing operation in superconductor manufacture to a stress larger than the magnet design stress, a 100% proof test is achieved; cabled conductors offer mechanical redundancy, as do some methods of conductor joining; ground-plane insulation should be multilayered to prevent arcs, and interturn and interlayer insulation spaced to be compatible with the self-extinguishing of arcs during quench voltages; electrical leads should be thermally protected; and guard vacuum spaces can be incorporated to control helium leaks.
Borders, Geography, and Oligopoly: Evidence from the Wind Turbine Industry

Abstract Using a microlevel data set of wind turbine installations in Denmark and Germany, we estimate a structural oligopoly model with cross-border trade and heterogeneous firms. Our approach separately identifies border-related from distance-related variable costs and bounds the fixed cost of exporting for each firm. In the data, firms’ market shares drop precipitously at the border. We find that 40% to 50% of the gap can be attributed to national border costs. Counterfactual analysis indicates that eliminating national border frictions would increase total welfare in the wind turbine industry by 4% in Denmark and 6% in Germany.
Testing the nullspace property using semidefinite programming

Recent results in compressed sensing show that, under certain conditions, the sparsest solution to an underdetermined set of linear equations can be recovered by solving a linear program. These results either rely on computing sparse eigenvalues of the design matrix or on properties of its nullspace. So far, no tractable algorithm is known to test these conditions and most current results rely on asymptotic properties of random matrices. Given a matrix A, we use semidefinite relaxation techniques to test the nullspace property on A and show on some numerical examples that these relaxation bounds can prove perfect recovery of sparse solutions with relatively high cardinality.
Collective field description of matrix cosmologies

We study the Das-Jevicki collective field description of arbitrary classical solutions in the c = 1 matrix model, which are believed to describe nontrivial spacetime backgrounds in 2d string theory. Our analysis naturally includes the case of a Fermi droplet cosmology: a finite size droplet of Fermi fluid, made up of a finite number of eigenvalues. We analyze properties of the coordinates in which the metric in the collective field theory is trivial, and comment on the form of the interaction terms in these coordinates.
Pulsar Pair Cascades in a Distorted Magnetic Dipole Field

We investigate the effect of a distorted neutron star dipole magnetic field on pulsar pair cascade multiplicity and pair death lines. Using a simple model for a distorted dipole field that produces an offset polar cap (PC), we derive the accelerating electric field above the PC in space-charge-limited flow. We find that even a modest azimuthally asymmetric distortion can significantly increase the accelerating electric field on one side of the PC and, combined with a smaller field line radius of curvature, leads to larger pair multiplicity. The death line for producing pairs by curvature radiation moves downward in the P-P-dot diagram, allowing high pair multiplicities in a larger percentage of the radio pulsar population. These results could have important implications for the radio pulsar population, high energy pulsed emission, and the pulsar contribution to cosmic ray positrons.
Local-global principles for representations of quadratic forms

We prove a local-global principle for the problem of representations of quadratic forms by quadratic forms over ℤ, in codimension ≥5. The proof uses the ergodic theory of p-adic groups, together with a fairly general observation on the structure of orbits of an arithmetic group acting on integral points of a variety.
Trade Reforms, Credibility, and Development

Abstract This paper analyzes the implications of uncertainty regarding the future course of trade liberalization on investment and policies. Uncertainty concerning the future tariff rate is shown to depress saving, and to operate as a subsidy (tax) on inward (outward) investment. We identify the need to tax (subsidize) private investment in the importable (exportable) sector. The elimination of sectorial private investment policies calls for a rise (drop) in the public/private capital ratio in the outward-oriented (inward-oriented) activities. In the presence of an external credit ceiling, a higher degree of risk aversion increases the magnitude (without changing the nature) of the policies.
Syntheses and pharmacological activity of N‐acyl‐substituted imidazolidinethiones and thioimidazolines

A series of imidazolidinethiones and thioimidazolines was synthesized and tested for their effects on both forced and spontaneous motor activities as well as their ability to raise the convulsion threshold. The N-acyl-substituted 2-p-fluorobenzylthioimidazolines were the most active compounds, producing protection against maximal electroshock seizures and tonic convulsions induced by pentylenetetrazol. Both compounds had high LD50 values and safety indexes.
Simulations and Analytic Calculations of Bubble Growth during Hydrogen Reionization

We present results from a large volume simulation of hydrogen reionization. We combine 3D radiative transfer calculations and an N-body simulation, describing structure formation in the intergalactic medium, to detail the growth of H II regions around high-redshift galaxies. Our simulation tracks 10243 dark matter particles, in a box of comoving side length 65.6 Mpc h-1. This large volume allows us to accurately characterize the size distribution of H II regions throughout most of the reionization process. At the same time, our simulation resolves many of the small galaxies likely responsible for reionization. It confirms a picture anticipated by analytic models: H II regions grow collectively around highly clustered sources and have a well-defined characteristic size, which evolves from a sub-Mpc scale at the beginning of reionization to R > 10 Mpc toward the end. We present a detailed statistical description of our results and compare them with a numerical scheme based on the analytic model by Furlanetto and coworkers. We find that the analytic calculation reproduces the size distribution of H II regions and the 21 cm power spectrum of the radiative transfer simulation remarkably well. The ionization field from the simulation, however, has more small-scale structure than the analytic calculation, owing to Poisson scatter in the simulated abundance of galaxies on small scales. We propose and validate a simple scheme to incorporate this scatter into our calculations. Our results suggest that analytic calculations are sufficiently accurate to aid in predicting and interpreting the results of future 21 cm surveys. In particular, our fast numerical scheme is useful for forecasting constraints from future 21 cm surveys and in constructing mock surveys to test data analysis procedures.
An Improved Synthesis of 5-Fluorothiophene-2-Carboxylic Acid

Abstract A new and efficient route to 5-fluorothiophene-2-carboxylic acid 1 was secured in two steps and 62% yield overall.
Synthesis of NPS R-568 utilizing titanium-catalyzed asymmetric hydrosilylation

Abstract The enantioselective hydrosilylation of imines catalyzed by an (EBTHI) Ti (EBTHI=ethylene-bis(η5-tetrahydroindenyl)) species was applied to the synthesis of NPS R-568, an active compound for the treatment of hyperparathyroidism.
Hematologic changes following burns.

Abstract These studies demonstrate statistically significant changes between the platelet counts, FDP and plasminogen levels, and C3 and 5-min kinin activity of three groups separated according to their prognostic indices. Subsequent analysis of survivors confirms these trends and reveals additional supporting test data. We postulate that intravascular contamination occurs following major burns due to tissue trauma, and continues as burn wound sepsis develops. Standard heparin therapy does not significantly inhibit Hageman factor, plasmin, complement, or kinin activation products. It is not surprising that this anticoagulant does not change FDP levels or modify the course of most burns; however, further studies are needed to clarify this situation.