cssi/SciSciGPT-SciSciNet huggingface dataset:
Perfect lattice actions for quarks and gluons

Abstract We use perturbation theory to construct perfect lattice actions for quarks and gluons. The renormalized trajectory for free massive quarks is identified by blocking directly from the continuum. We tune a parameter in the renormalization group transformation such that for 1d configurations the perfect action reduces to the nearest-neighbor Wilson fermion action. The fixed point action for free gluons is also obtained by blocking from the continuum. For 2d configurations it reduces to the standard plaquette action. Classically perfect quark and gluon fields, quark-gluon composite operators and vector and axial vector currents are constructed as well. Also the quark-antiquark potential is derived from the classically perfect Polyakov loop. The quark-gluon and three-gluon perfect vertex functions are determined to leading order in the gauge coupling. This work provides a basis for the numerical construction of a lattice action for QCD, which is (approximately) perfect even beyond perturbation theory.
Towards a 4d/2d correspondence for Sicilian quivers

We study the 4d/2d AGT correspondence between four-dimensional instanton counting and two-dimensional conformal blocks for generalized SU(2) quiver gauge theories coming from punctured Gaiotto curves of arbitrary genus. We propose a conformal block description that corresponds to the elementary SU(2) trifundamental half-hypermultiplet, and check it against Sp(1) − SO(4) instanton counting.
Parametric optimization of waveguide Raman spectroscopy in the near-IR

Abstract Waveguide Raman spectroscopy (WRS) has shown considerable potential for investigating the chemistry of thin films and interfaces in a number of fields, including microelectronics, imaging, optics, and coating technology. One of the major problems associated with Raman spectroscopy has been the presence of fluorescence, greatly limiting the investigation of thin films which are colored. To circumvent this difficulty, WRS sampling techniques have been extended to Fourier transform Raman spectroscopy where near-IR excitation is used. In doing this, the increase in wavelenght and the resulting decrease in the refractive index of the film combine to restrict the film thicknesses which can be studied. The effect of the excitation wavelength on the distribution of the optical field in the waveguide and its effect on WRS measurements are discussed.
Direct presentment regulation in payments

Abstract There are two alternative methods of supporting interbank exchange of payments: payment exchange may be supported by a direct presentment regulation, which obligates a paying bank to make payment in full to whomever delivers the payment instrument to it; alternatively the interbank exchange of payments may be governed by private contracts. Examples of the two cases are provided in the U.S. by cheques, which are subject to direct presentment regulations, and credit cards and debit cards, which are governed by private contracts. A model in which the interchange fee charged by banks under a collective agreement to clear payments can be used as an instrument of tacit collusion, is examined. However, under direct presentment, the equilibrium fee, for a range of the parameter set, is set to zero. At the same time, because, under direct presentment, it is difficult to exclude banks from issuing payments, banks have incentives to impede the collection of payments. One way they can do so is through the strategy of remote disbursement, in which banks intentionally delay payments. A collectively-owned entity, or a public one, that quickly presents cheques to the banks engaging in the remote presentment strategy can work to overcome the incentives to remotely present the cheques, but at a resource cost. Assuming a monopoly multilateral agreement for the privately contracted payment instrument, the interchange fee specified by the contract is an instrument of tacit collusion and can in some circumstances support the monopoly outcome. However, it avoids the problem of attempts to impede payments. These results naturally lead to an exploration of whether direct presentment regulations should be changed, so that all payment instruments that transfer bank liabilities can be governed by private contract. L51, L16, L9.
Evaluation of Green's function integrals in conducting media

This work presents an accurate integration method for computing Green's function operators related to lossy conducting media. The presented approach is ultrawideband, i.e., the integration schemes cover the entire range of frequency behavior, from high frequencies where skin current is prevalent to low frequencies where volume current flow dominates. The scheme is a step toward permitting exact ultrawide-band frequency domain surface-only-based integral-equation simulation of arbitrarily-shaped three-dimensional conductors, and toward obviating the need for volume-based explicit frequency-dependent skin effect modeling. This work deals specifically with the computation of Green's functions and not with the unrelated but important low-frequency conditioning issue associated with the standard electric field integral equation.
Stigma and Self-Fulfilling Expectations of Criminality

A convicted criminal suffers not only from public penalties but from stigma, the reluctance of others to interact with him economically and socially. Conviction can convey useful information about the convicted, which makes stigmatization an important and legitimate function of the criminal justice system quite apart from moral considerations. The magnitude of stigma depends on expectations and the crime rate, however, which can lead to multiple, Pareto-ranked equilibria with different amounts of crime.
Steady-state heat transport: Ballistic-to-diffusive with Fourier's law

It is generally understood that Fourier's law does not describe ballistic phonon transport, which is important when the length of a material is similar to the phonon mean-free-path. Using an approach adapted from electron transport, we demonstrate that Fourier's law and the heat equation do capture ballistic effects, including temperature jumps at ideal contacts, and are thus applicable on all length scales. Local thermal equilibrium is not assumed, because allowing the phonon distribution to be out-of-equilibrium is important for ballistic and quasi-ballistic transport. The key to including the non-equilibrium nature of the phonon population is to apply the proper boundary conditions to the heat equation. Simple analytical solutions are derived, showing that (i) the magnitude of the temperature jumps is simply related to the material properties and (ii) the observation of reduced apparent thermal conductivity physically stems from a reduction in the temperature gradient and not from a reduction in actual thermal conductivity. We demonstrate how our approach, equivalent to Fourier's law, easily reproduces results of the Boltzmann transport equation, in all transport regimes, even when using a full phonon dispersion and mean-free-path distribution.
Pilgrim Trust Lecture. Organization of American Scientists for the War

In ordinary times any American scientist would deem it a distinguished honour to be nominated as the Pilgrim Trust lecturer. In these extraordinary times the significance of this lectureship is enhanced by the fact that American and British scientists are working hand in hand, not only to advance science as an important aspect of man’s culture, but now especially as a powerful tool for the preservation of our opportunities for continued life, liberty and pursuit of happiness. Consequently, when Sir Henry Tizard transmitted your invitation for me to deliver this lecture I accepted the invitation with profound appreciation and humility.
Black-Hole Spin Dependence in the Light Curves of Tidal Disruption Events

A star orbiting a supermassive black hole can be tidally disrupted if the black hole's gravitational tidal field exceeds the star's self gravity at pericenter. Some of this stellar tidal debris can become gravitationally bound to the black hole, leading to a bright electromagnetic flare with bolometric luminosity proportional to the rate at which material falls back to pericenter. In the Newtonian limit, this flare will have a light curve that scales as ${t}^{\ensuremath{-}5/3}$ if the tidal debris has a flat distribution in binding energy. We investigate the time dependence of the black-hole mass accretion rate when tidal disruption occurs close enough the black hole that relativistic effects are significant. We find that for orbits with pericenters comparable to the radius of the marginally bound circular orbit, relativistic effects can double the peak accretion rate and halve the time it takes to reach this peak accretion rate. The accretion rate depends on both the magnitude of the black-hole spin and its orientation with respect to the stellar orbit; for orbits with a given pericenter radius in Boyer-Lindquist coordinates, a maximal black-hole spin anti-aligned with the orbital angular momentum leads to the largest peak accretion rate.
Recent progress in the synthesis and characterization of amorphous and crystalline carbon nitride coatings

This review summarizes our most recent findings in the structure and properties of amorphous and crystalline carbon nitride coatings, synthesized by reactive magnetron sputtering. By careful control of the plasma conditions via proper choice of process parameters such as substrate bias, target power and gas pressure, one can precisely control film structure and properties. With this approach, we were able to produce amorphous carbon nitride films with controlled hardness and surface roughness. In particular, we can synthesize ultrathin (1 nm thick) amorphous carbon nitride films to be sufficiently dense and uniform that they provide adequate corrosion protection for hard disk applications. We demonstrated the strong correlation between ZrN(111) texture and hardness in CNx/ZrN superlattice coatings. Raman spectroscopy and near-edge x-ray absorption show the predominance of sp3-bonded carbon in these superlattice coatings.
Compressibility effects on ideal and kinetic ballooning modes and elimination of finite Larmor radius stabilization

The dynamics of ideal and kinetic ballooning modes are considered analytically including parallel ion dynamics, but without electron dissipation. For ideal modes and typical tokamak parameters, parallel dynamics predominantly determine the growth rate when β is within ∼20%–40% of the ideal threshold, resulting in a substantial reduction in growth rate. Compressibility also eliminates the stabilization effects of finite Larmor radius (FLR); FLR effects (when temperature gradients are neglected) can even increase the growth rate above the magnetohydrodynamic (MHD) value. Temperature gradients accentuate this by adding a new source of free energy independent of the MHD drive, in the region of ballooning coordinate corresponding in MHD to the continuum. Analytic dispersion relations are derived demonstrating the effects above; the formalism emphasizes the similarities between the ideal MHD and kinetic cases.
Cooperative relaying architecture for wireless video sensor networks

We propose a new cooperative relaying architecture for delivering aggregated high-rate video data to the destination (base station) in wireless sensor networks. The proposed approach is to make each relay node to detect only a subset (called sub-stream) of the data stream and all relay nodes to forward their sub-streams simultaneously over the same physical channel. Then, multiple receive antennas at the destination allow the sub-streams to be detected separately based on their spatial characteristics. The distinctive benefit of this approach is the reduction of transmit and receive processing requirements on each relay node, while providing significant savings in the transmit and receive energy, particularly in the high spectral efficiency regime. Therefore, the proposed approach is particularly attractive for sending high-rate video data in wireless sensor networks, where each relay can handle only low-rates due to limited resources in terms of energy, bandwidth, hardware, and space (size). The proposed relaying architecture also provides an additional physical layer security mechanism over the traditional network layer security provision mechanisms
Rh-catalyzed Transannulation of N-Tosyl-1,2,3-Triazoles with Terminal Alkynes

The first transannulation of 1,2,3-triazoles with terminal alkynes into pyrroles is reported. The reaction proceeds in the presence of a Rh2(oct)4/AgOCOCF3 binary catalyst system providing a straightforward approach to 1,2,4-trisubstituted pyrroles in good to excellent yields.
Credit Ratings and Security Prices in the Subprime MBS Market

We present and discuss preliminary evidence suggesting that credit ratings significantly influenced prices for subprime mortgage-backed securities issued in the period leading up to the recent financial crisis. Ratings are closely correlated with prices even controlling for a rich set of security- and loan-level controls. This incremental variation in ratings has much less predictive power for security defaults, however, based on findings to date from our ongoing research, suggesting prices were excessively sensitive to ratings relative to their informational content.
Projection decomposition in multiplier algebras

In this paper we present new structural information about the multiplier algebra $${\mathcal M (\mathcal A )}$$ of a σ-unital purely infinite simple C*-algebra $${\mathcal {A}}$$ , by characterizing the positive elements $${A\in \mathcal M (\mathcal A )}$$ that are strict sums of projections belonging to $${\mathcal A }$$ . If $${A\not\in \mathcal {A}}$$ and A itself is not a projection, then the necessary and sufficient condition for A to be a strict sum of projections belonging to $${\mathcal {A} }$$ is that $${\|A\| >1 }$$ and that the essential norm $${\|A\|_{ess} \geq 1}$$ . Based on a generalization of the Perera–Rordam weak divisibility of separable simple C*-algebras of real rank zero to all σ-unital simple C*-algebras of real rank zero, we show that every positive element of $${\mathcal {A}}$$ with norm >1 can be approximated by finite sums of projections. Based on block tri-diagonal approximations, we decompose any positive element $${A\in \mathcal M (\mathcal {A} )}$$ with $${\| A\| >1 }$$ and $${\| A\|_{ess} \geq 1}$$ into a strictly converging sum of positive elements in $${\mathcal A}$$ with norm >1.
A General Synthetic Approach to the (20S)-Camptothecin Family of Antitumor Agents by a Regiocontrolled Cascade Radical Cyclization of Aryl Isonitriles

The power of radical reactions continues to increase! A cascade radical annulation route now allows perhaps the mildest and most general method for the synthesis of both known and new members of the camptothecin family (parent structure on the right) of antitumor agents.
The ionospheric gravity and diamagnetic current systems

[1] Large-scale currents in the ionosphere are driven by a variety of sources, including neutral winds, gravity, and plasma pressure gradients. While the stronger daytime wind-driven currents have been extensively studied, gravity and diamagnetic currents in the ionosphere have received very little attention but can have substantial effects even during the night. With the availability of a new generation of magnetic field models based on high-accuracy satellite magnetic measurements, it becomes increasingly important to account for these smaller current systems. In this work, we use the stand-alone NCAR TIEGCM electrodynamics solver along with empirical density, wind, and temperature inputs to model the global current systems caused by gravity and diamagnetism in the F region ionosphere and calculate their magnetic perturbations. These results allow us for the first time to visualize the global structure of these currents and quantify their magnetic perturbations. We find a significantly higher gravity-driven current during the night than one would expect from the lower conductivity which is primarily due to a Pedersen current driven by polarization charges in the predawn sector. We find some discrepancies between the diamagnetic perturbation and a theoretical prediction which could be a result of magnetic tension due to the curvature of the geomagnetic field lines. These results will allow geomagnetic field modelers to account for these important current systems and create more accurate models. This work will also be crucial in analyzing ionospheric magnetic field measurements from upcoming satellite missions such as Swarm.
Tris(3,6-Dioxaheptyl)amine as a Phase-Transfer Catalyst in Phenacyl Ester Synthesis

Abstract Tris(3,6-dioxaheptyl)amine (TDA-1) may be substituted for toxic crown ethers in the phase-transfer catalyzed synthesis of phenacyl esters from weakly nucleophilic potassium carboxylates and α, p-dibromoacetophenone in acetonitrile.
Intramolecular 4 + 3 Cycloadditions. Cycloaddition Reactions of Cyclic Alkoxyallylic and Oxyallylic Cations

The intramolecular 4 + 3 cycloaddition of oxyallylic and alkoxyallylic cations has been studied. Cyclopentenyl oxyallylic cations tethered to a furan by a three or four carbon chain react with high stereoselectivity via a compact (endo) transition state analogous to that seen in intermolecular cycloadditions. Six- through eight-membered oxyallylic cations react differently and give increasingly larger amounts of cycloadduct derived from extended (exo) transition states. This has been rationalized on the basis of ring strain in the endo transition states in this series. Cyclodecenyl oxyallylic cations are sickle-shaped and stereoselectively undergo cycloaddition via extended transition states to a furan diene tethered by three carbons. Cyclododecenyl oxyallylic cations behave similarly, although the evidence suggests that a small amount of W-shaped cation also is formed. Cyclic alkoxyallylic sulfones give rise to the corresponding cations upon treatment with TiCl4, and the latter give rise to cycloadducts ...
Synthesis of (+)-Complanadine A, an Inducer of Neurotrophic Factor Excretion

A total synthesis of the Lycopodium alkaloid (+)-complanadine A is described. Complanadine A has been shown to induce the secretion of neurotrophic factors from 1321N1 cells, promoting the differentiation of PC-12 cells. The use of a simplifying metal mediated [2+2+2] + [2+2+2] sequence using a silyl-substituted diyne and 2 equiv of the corresponding alkyne-nitrile has provided rapid access to the natural product.
RICCI DEFECTS OF MICROLOCALIZED EINSTEIN METRICS

This is the third and last in our series of papers concerning rough solutions of the Einstein vacuum equations expressed relative to wave coordinates. In this paper we prove an important result, concerning Ricci defects of microlocalized solutions, stated and used in the proof of the crucial Asymptotics Theorem in [1]. The result is of independent interest in situations when one has to smooth out the given spacetime metric in order to achieve good causality properties.
Viscous oscillating cascade aerodynamics and flutter by a locally analytical method

A mathematical model is developed to analyze the viscous aerodynamics of an harmonically oscillating flat plate airfoil cascade in an incompressible laminar flow. The steady flow field is described by the Navier-Stokes equations, with the unsteady viscous flow modeled as a small perturbation to this steady flow. Solutions for both the steady and the unsteady viscous flow fields are then obtained by developing locally analytical solutions. The significant effects of Reynolds number, elastic axis, interblade phase angle and incidence angle on the oscillating cascade unsteady aerodynamics and torsional flutter characteristics are then demonstrated.
Image Compression Scheme Based on Multi-resolution Boundary-Based Shape Descriptors

With the development of the internet, image compression becomes more and more essential. Most multi-media based web applications are far from realizing their full potential largely due to the limitations of the traditional image compression methods. Representing a shape only based on its boundary information, the boundary-based shape descriptors are prospective for image compression. Inspired by how brain recalls objects, we propose a novel image compression scheme. This scheme can transform any boundary-based descriptor to its multi-resolution structure. The multi-resolution descriptor represents an image in a cognitive architecture which is idea for image compression with maintaining the global information and the key detail points of this image. This scheme has high computation accuracy and efficiency, strong flexibility, it is free from parameter settings, robust to errors and not restricted by the image formats.
Functional imaging of the brain by MRI

Recent developments in Magnetic Resonance Imaging (MRI) enabling imaging of hemodynamics and metabolism hold significant promise in the noninvasive evaluation of normal and abnormal brain function. Among several methods, the most successful approach exploits the sensitivity of MRI to changes in the oxygenation status of hemoglobin (oxy/deoxyhemoglobin) in red blood cells related to local variations in blood flow and oxygen consumption in tissues. In cerebral cortex, such variations may be induced by external stimuli or internal cognitive processes. Typically, MRI signal slightly increases when brain is activated due to increase in oxygen supply (blood flow). These studies suggest that MRI may be the method of choice to study mental and cognitive processes underlying the function of the human brain.
Tris(2-pyridyl) tripod ligands

Abstract This review covers the recent literature involving tris(2-pyridyl) tripod ligands which use nitrogen, phosphorus, arsenic, or carbon as central bridging atoms. In general, tripod ligands are facially coordinating, tridentate chelate ligands which have received considerable attention in both coordination and organometallic chemistry. Over the past 20 years, there have been hundreds of published reports concerning various aspects of metal complexes which contain tripod ligands, with the majority of these reports involving polypyrazolylborate ligands. In light of the extensive and also very recent literature coverage of ligands which contain pyrazole donors, this review is a timely examination of the literature concerning tripod ligands that use pyridine donors. Further, this review contains the first summary of the chemistry of carbon-bridged tris(2-pyridyl) tripod ligands as well as an examination of recent studies involving nitrogen-bridged, phosphorus-bridged and arsenic-bridged analogues to the carbon-bridged ligands. There is a particular focus on tris(2-pyridyl) tripod ligands that coordinate in a facial manner to a single metal center through the pyridyl nitrogens.
Compliant Mechanical Amplifier Design using Multiple Optimally Placed Actuators

This article discusses a methodology for designing compliant mechanisms with piezoelectric actuation to obtain maximum deflection and force at the output point. The focus is on design of compliant mechanisms with multiple piezoelectric actuators. The number, size, and position of the actuators within the compliant mechanism are optimized for the maximum output deflection. Predicted results demonstrate that compliant mechanisms with multiple, optimally placed actuators outperform those with a single actuator placed at a predetermined location.
New estimates of the vital rates of the United States black population during the nineteenth century

The difficulties of obtaining credible estimates of vital rates for the black population throughout the entire nineteenth century are overcome in this study. The methodology employed the notion of deviating networks of mortality rates for each general mortality level, which was taken from the United Nations studyThe Concept of a Stable Population. Period life tables and vital rates for intercensal periods were generated from the new estimates of the black population at each census date. The results of this study are highly compatible both with the life tables for the death-registration states in the twentieth century and the recent Coale and Rives reconstruction for the period from 1880 to 1970 and with several estimates of vital rates previously made for the mid-nineteenth century. This study places the mean life expectancy at birth for the black population during the nineteenth century at about 33.7 years for both sexes. The infant death rate (1000m (0)) is shown to have varied between 222 and 237 for females and between 266 and 278 for males. The intrinsic crude death rate centered on 30.4 per thousand during the century, while the birth rate declined from 53.2 early in the century to about 43.8 at the end.
Efficient algorithms for universal portfolios

A constant rebalanced portfolio is an investment strategy that keeps the same distribution of wealth among a set of stocks from day to day. There has been much work on Cover's Universal algorithm, which is competitive with the best constant rebalanced portfolio determined in hindsight (Cover, 1991, Helmbold et al, 1998, Blum and Kalai, 1999, Foster and Vohra, 1999, Vovk, 1998, Cover and Ordentlich, 1996a, Cover, 1996c). While this algorithm has good performance guarantees, all known implementations are exponential in the number of stocks, restricting the number of stocks used in experiments (Helmbold et al, 1998, Cover and Ordentlich, 1996a, Ordentlich and Cover, 1996b, Cover, 1996c, Blum and Kalai, 1999). We present an efficient implementation of the Universal algorithm that is based on non-uniform random walks that are rapidly mixing (Applegate and Kannan, 1991, Lovasz and Simonovits, 1992, Frieze and Kannan, 1999). This same implementation also works for non-financial applications of the Universal algorithm, such as data compression (Cover, 1996c) and language modeling (Chen et al, 1999).
New, Scalable Route for the Synthesis of a trans-Fused Hexahydro-1H-phenanthren-2-one from a Conjugated Tetrahydro-3H-phenanthren-2-one

Abstract A three-step, readily scalable route for the conversion of a ring-conjugated tetrahydro-3H-phenanthren-2-one to a trans-fused hexahydro-1H-phenanthren-2-one is described. The key step is the hydrogenation of a double bond using a nearby ketal moiety to assist in the stereoselective delivery of the hydrogen.
Quantifying tax effects under policy foresight

Abstract Studies of tax effects make the conventional information assumption that changes in period-t taxes become known at t. Legislative lags, however, imply that news arrives before tax changes take place. Under policy foreknowledge, the conventional information structure is therefore misspecified. Simulations of a standard neoclassical growth model suggest that foresight of only one quarter can distort substantially the estimates of tax effects obtained under the no-foresight assumption. Also, it is crucial to model capital and labor taxes separately: anticipated changes in these two tax policies have opposite effects on consumption, investment, labor, and output before policy realization.
Subjective Quantitative Studies of Human Agency

Amartya Sen’s writings have articulated the importance of human agency, and identified the need for information on agency freedom to inform our evaluation of social arrangements. Many approaches to poverty reduction stress the need for empowerment. This paper reviews subjective quantitative measures of human agency at the individual level. It introduces large-scale cross-cultural psychological studies of self-direction, of autonomy, of self-efficacy, and of self-determination. Such studies and approaches have largely developed along an independent academic path from economic development and poverty reduction literature, yet may be quite significant in crafting appropriate indicators of individual empowerment or human agency. The purpose of this paper is to note avenues of collaborative enquiry that might be fruitful to develop.
SPITZER OBSERVATIONS OF A GRAVITATIONALLY LENSED QUASAR, QSO 2237+0305

The four-image gravitationally lensed quasar QSO 2237+0305 is microlensed by stars in the lens galaxy. The amplitude of microlensing variability can be used to infer the relative size of the quasar as a function of wavelength; this provides a test of quasar models. Toward this end, we present Spitzer Space Telescope Infrared Spectrograph and Infrared Array Camera (IRAC) observations of QSO 2237+0305, finding the following. (1) The infrared (IR) spectral energy distribution (SED) is similar to that of other bright radio-quiet quasars, contrary to an earlier claim. (2) A dusty torus model with a small opening angle fits the overall shape of the IR SED well, but the quantitative agreement is poor due to an offset in wavelength of the silicate feature. (3) The flux ratios of the four lensed images can be derived from the IRAC data despite being unresolved. We find that the near-IR fluxes are increasingly affected by microlensing toward shorter wavelengths. (4) The wavelength dependence of the IRAC flux ratios is consistent with the standard quasar model in which an accretion disk and a dusty torus both contribute near 1 μm in the rest frame. This is also consistent with recent IR spectropolarimetry of nearby quasars.
Matching of Hecke operators for exceptional dual pair correspondences

Abstract Let G be a split algebraic group of type E n defined over a p-adic field. This group contains a dual pair G × G ′ where one of the groups is of type G 2 . The minimal representation of G, when restricted to the dual pair, gives a correspondence of representations of the two groups in the dual pair. We prove a matching of spherical Hecke algebras of G and G ′ , when acting on the minimal representation. This implies that the correspondence is functorial, in the sense of Arthur and Langlands, for spherical representations.
Acid catalyzed functionalization of rapamycin

Abstract Rapamycin rapidly undergoes demethoxylation at C-7 in the presence of Lewis acids (BF 3 ·Et 2 O, SnCl 4 etc.) to give a highly stabilized carbocation. This intermediate gives a tetraene or is trapped by nucleophiles to give functionalized trienes. Several examples of the substitution reaction and elaboration of the reaction scheme are reported.
The first L p -cohomology of some groups with one end

Let p be a real number greater than one. In this paper we study the vanishing and nonvanishing of the first Lp-cohomology space of some groups that have one end. We also make a connection between the first Lp-cohomolgy space and the Floyd boundary of the Cayley graph of a group. We apply the result about Floyd boundaries to show that there exists a real number p such that the first Lp-cohomology space of a nonelementary hyperbolic group does not vanish.
On the absence of McShane-type identities for the outer space

Abstract A remarkable result of McShane states that for a punctured torus with a complete finite volume hyperbolic metric we have ∑ γ 1 e l ( γ ) + 1 = 1 2 where γ varies over the homotopy classes of essential simple closed curves and l ( γ ) is the length of the geodesic representative of γ. We prove that there is no reasonable analogue of McShane's identity for the Culler–Vogtmann outer space of a free group.
Effect of the theta aurora on the polar thermosphere

Abstract The theta aurora is characterized by a transpolar auroral arc, connecting the dayside to the nightside auroral oval. It is observed during geomagnetically quiet times when the polar cap becomes contracted. A high-resolution time-dependent model of the global thermosphere is used to estimate the effects of the transpolar arc on the polar thermosphere. A background ionospheric model is assumed, and a simple but physically reasonable representation of the ionospheric conditions within the transpolar arc is “superimposed” on the background ionosphere. The thermospheric model is then solved both with and without the imposed transpolar arc to determine the arc's effects on the neutral gas. In particular, percentage changes in thermospheric mass density and temperature are computed. These percentage differences are seen to vary systematically with the level of the ionospheric density enhancement within the arc. A strong dependence on solar activity level is also noted. While results are presented mainly for an altitude of 300 km, the typical variation of these results with altitude is also illustrated.
Active detection of small quantities of shielded highly-enriched uranium using low-dose 60-kev neutron interrogation

Abstract Active interrogation with low-energy neutrons provides a search technique for highly-enriched uranium concealed in cargo. We describe the technique and show initial results using a low-dose 60-keV neutron beam. This technique produces a clear induced fission signal in the presence of small quantities of 235 U. The technique has been validated with low-Z and high-Z cargo materials. The technique uses a forward-directed beam of 60-keV neutrons to induce fission in 235 U. Detection of the fast fission neutrons with pulse-shape discriminating scintillators is then the signature for 235 U. The beam of neutrons is generated with a 1.93 MeV proton beam impinging on a natural lithium target. The proton beam is produced by a radio-frequency quadrupole LINAC. The 60 keV neutron beam is forward-directed because the 7 Li(p, n) reaction is just above threshold for a proton energy of 1.93 MeV.
Bounds on the Network Coding Capacity for Wireless Random Networks

Recently, it has been shown that the max flow capacity can be achieved in a multicast network using network coding. In this paper, we propose and analyze a more realistic model for wireless random networks. We prove that the capacity of network coding for this model is concentrated around the expected value of its minimum cut. Furthermore, we establish upper and lower bounds for wireless nodes using Chernoff bounds. Our experiments show that our theoretical predictions are well matched by simulation results.
A Future for Organization Theory: Living in and Living with Changing Organizations

We believe that the field of organization theory is adrift. In sailing jargon, we are “in irons”---stalled and making little headway toward understanding organizations and their place in our lives. We first attempt to diagnose our maladies and then, in this light, offer three broad research questions that just might reinvigorate our work: First, how can we understand today's changing organizations? Second, how can we live in these organizations? And third, how can we best live with them? We close by calling attention to how our familiar approaches to building and testing theory might hamper any attempt to revitalize our field.
Repeated gastric distension alters food intake and neuroendocrine profiles in rats.

The consumption of a large food bolus leads to stomach distension. Gastric distension potently signals the termination of a meal by stimulating gastric mechanoreceptors and activating neuroendocrine circuitry. The ability to terminate a meal is altered in disorders such as bulimia nervosa (BN), binge-eating disorder (BED) and certain subtypes of obesity in which large quantities of food are frequently ingested. When a large meal is consumed, the stomach is rapidly stretched. We modeled this rapid distension of the stomach in order to determine if the neuroendocrine abnormalities present in these disorders, including increased gastric capacit3y, leptin dysregulation, and alterations in neuropeptide Y (NPY), and proopiomelanocortin (POMC) expression, were influenced by the rapid stretch aspect of repeatedly consuming a large meal. To test the effects of repeated gastric distension (RGD) on neuroendocrine factors involved in energy homeostasis, a permanent intra-gastric balloon was implanted in rats, and briefly inflated daily for 4 weeks. Though body weights and daily food intakes remained equivalent in RGD and control rats, a significant delay in the onset of feeding was present during the first and second, but not the third and fourth weeks of inflations. Despite equivalent body weights and daily caloric consumption, RGD animals had significantly decreased leptin levels (p < 0.05), and tended to have increased fasting arcuate NPY levels (p = 0.08), which were suppressed more than control animals following food intake (control and RGD decreases from baseline were 184.95% and 257.42%, respectively). NPY expression in the nucleus of the solitary tract followed a similar pattern. These data demonstrate that the act of regularly distending the stomach can have effects on the regulation of energy balance that are independent from those related to caloric consumption, and may be related to disorders such as BN, BED, and certain types of obesity in which meal termination is impaired.
Lewis Acid-Mediated Reactions of Alkyl Azides with α,β-Unsaturated Ketones

Alkyl azides react with saturated ketones upon treatment with Lewis acids to afford ring-expansion products through the azido-Schmidt reaction, but this reaction does not proceed when α,β-unsaturated ketones are used. In this study, alkyl azides were reacted with enones in the presence of Lewis acids to give enaminones (vinylogous amides), which formally involve a ring contraction reaction. The mechanism and scope of this reaction is discussed.
Lower bounds for off-line range searching

This paper proves three lower bounds for variants of the following rangesearching problem: Given n weighted points inR d andn axis-parallel boxes, compute the sum of the weights within each box: (1) if both additions and subtractions are allowed, we prove that Ω(n log logn) is a lower bound on the number of arithmetic operations; (2) if subtractions are disallowed the lower bound becomes Ω(n(logn/loglogn)d-1), which is nearly optimal; (3) finally, for the case where boxes are replaced by simplices, we establish a quasi-optimal lower bound of Ω(n2-2/(d+1))/polylog(n).
Effect of lower-extremity muscle fatigue on postural control.

Abstract Gribble PA, Hertel J. Effect of lower- extremity muscle fatigue on postural control. Arch Phys Med Rehabil 2004;85:589–92. Objective To examine the effects of fatigue of the lower extremity on postural control during single-leg stance. Design Pretest-posttest. Setting University research laboratory. Participants Fourteen healthy volunteers (age, 21±2y) with no history of lower-extremity injury or neurologic deficits. Interventions Testing consisted of isokinetically fatiguing the sagittal plane movers of the ankle, knee, or hip with measures of static postural control. Postural control was assessed with three 30-second trials during unilateral stance with eyes open. Main outcome measure Center of pressure excursion velocity (COPV) in the frontal and sagittal planes. Results Fatigue at the knee and hip led to postural control impairment in the frontal plane, whereas fatigue at the ankle did not. In the sagittal plane, fatigue at all 3 joints contributed to postural control impairment. Conclusions Our results suggest that there is an effect of localized fatigue of the sagittal plane movers of the lower extremity on COPV. It appears that fatigue about the hip and knee had a greater adverse affect on COPV.
Ion Transport in Ca(2+), Sr(2+), Ba(2+), and Pb(2+), Beta' Aluminas.

Abstract Single crystals of Ca2+, Sr2+, Ba2+, and Pb2+ beta″ alumina were prepared from sodium beta″ alumina by ion exchange. The ionic conductivities of Ca2+, Sr2+, and Ba2+ beta″ alumina are comparable, about 3 × 10−2 (ohm-cm)−1 at 300°C. Surprisingly, Pb2+ beta″ alumina is much more conductive, 1.5 × 10−1 (ohm-cm)−1 at 300°C and 4.6 × 10−3 (ohm-cm)−1 at 40°C. Its conductivity approaches that of sodium beta″ alumina at temperatures below 25°C. The diffusion coefficient for Sr2+ in beta″ alumina at 600°C was estimated from radiotracer experiments. It is consistent with that expected from conductivity measurements.
Contact resistance and methods for its determination

Abstract The problem of low resistance ohmic contacts to silicon has been of considerable technological interest. In recent years this problem has received special attention owing to the effect of scaling in very-large-scale integration (VLSI) technology. The field of ohmic contacts to semiconductors comprises two independent parts. First there exists the material science aspect. The choice of a suitable metallization system, the proper semiconductor parameters and the method of the contact formation is not obvious. Then there is the question of the proper definition of the contact resistance and the way it is measured. Several methods for contact resistance determination have been introduced in the past. All seem to have some drawbacks that either limit their usefulness or raise doubts as to their validity in certain situations. We shall discuss the two-, three- and four-terminal resistor methods of measurement. Relevant theoretical considerations will also be included. For conventional integrated circuits with a moderate junction depth of 1–2 μm, aluminum is uniquely suited as a single-element metallization system. However, for VLSI applications it may become obsolete because of several well-defined metallurgical problems. Thus, other metallization systems have to be investigated. We shall briefly discuss some recent data on several other metallization systems. Finally, the problem of size effects on the contact resistance will be discussed. Recent experimental results suggest important clues regarding the development of alternative metallization systems for VLSI circuits and also point to revisions of estimates of achievable design rules.
Structure and motion from line segments in multiple images

This paper presents a new method for recovering the three dimensional structure of a scene composed of straight line segments using the image data obtained from a moving camera. The recovery algorithm is formulated in terms of an objective function which measures the total squared distance in the image plane between the observed edge segments and the projections (perspective) of the reconstructed lines. This objective function is minimized with respect to the line parameters and the camera positions to obtain an estimate for the structure of the scene. The effectiveness of this approach is demonstrated quantitatively through extensive simulations and qualitatively with actual image sequences. The implementation is being made publicly available. >
Large-Amplitude Random Response of Angle-Ply Laminated Composite Plates

Large a m p l i t u d e response o f a n t i s y m m e t r i c angl e -p l y l a m i n a t e d r e c t a n g u l a r pane l s s u b j e c t e d t o broadband random a c o u s t i c e x c i t a t i o n i s s t u d i e d a n a l y t i c a l l y . The boundary c o n d i t i o n s cons ide red a r e a l l t h e edges s i m p l y suppo r ted and a l l t h e edges clamped. I n p l a n e edge c o n d i t i o n s cons ide red a r e immovable and movable f o r each o f t h e above cases. Mean-square d e f l e c t i o n s , mean-square s t r a i n s / s t r e s s e s , and e q u i v a l e n t l i n e a r f r e q u e n c i e s a t v a r i o u s a c o u s t i c l o a d i n g s a r e o b t a i n e d f o r l a m i n a t e s o f d i f f e r e n t l e n g t h t o w i d t h r a t i o s , l a m i n a t i o n ang les , number o f l a y e r s , and panel damping r a t i o s . R e s u l t s o b t a i n e d p n be used as a gu ide f o r s o n i c f a t i g u e des ign o f a n g l e p l y l a m i n a t e d pane ls under h i g h n o i s e env i ronment .
Interstellar Reservoirs of Cometary Matter

We review the evidence for the products of interstellar chemistry in volatile cometary matter. We compare the organic inventory of star-forming cores with that measured in various comets and point out the similarities and differences. The conditions necessary to fractionate interstellar molecules in the heavier isotopes of H, C, O and N are summarised and compared to the measured fractionation ratios in cometary ices. We give a list of future measurements that would shed further light on the putative connection between cometary and interstellar molecules.
Transport of Neptunium Through Yucca Mountain Tuffs

Neptunium has a high solubility in groundwaters from Yucca Mountain [1]. Uranium in nuclear reactors produces 237 Np which has a half-life of 2.14 × 106 years. Consequently, the transport of 237 Np through tuffs is of major importance in assessing the performance of a high-level nuclear waste repository at Yucca Mountain. The objective of this work is to determine the amount of Np retardation that is provided by the minerals in Yucca Mountain tuffs as a function of groundwater chemistry.
A one-pot synthesis of unsymmetrical bis-styrylbenzenes

An efficient and widely applicable one-pot synthesis of unsymmetrical (E,E)-bis-styrylbenzenes using successive Heck and Horner–Wadsworth–Emmons reactions is described.
Embedding Lagrangian Sink Particles in Eulerian Grids

We introduce a new computational method for embedding Lagrangian sink particles into a Eulerian calculation. Simulations of gravitational collapse or accretion generally produce regions whose density greatly exceeds the mean density in the simulation. These dense regions require extremely small time steps to maintain numerical stability. Smoothed particle hydrodynamics (SPH) codes approach this problem by introducing nongaseous, accreting sink particles, and Eulerian codes may introduce fixed sink cells. However, until now there has been no approach that allows Eulerian codes to follow accretion onto multiple, moving objects. We have removed that limitation by extending the sink particle capability to Eulerian hydrodynamics codes. We have tested this new method and found that it produces excellent agreement with analytic solutions. In analyzing our sink particle method, we present a method for evaluating the disk viscosity parameter α due to the numerical viscosity of a hydrodynamics code and use it to compute α for our Cartesian adaptive mesh refinement (AMR) code. We also present a simple application of this new method: studying the transition from Bondi to Bondi-Hoyle accretion that occurs when a shock hits a particle undergoing Bondi accretion.
Reducing tile complexity for self-assembly through temperature programming

We consider the tile self-assembly model and how tile complexity can be eliminated by permitting the temperature of the self-assembly system to be adjusted throughout the assembly process. To do this, we propose novel techniques for designing tile sets that permit an arbitrary length m binary number to be encoded into a sequence of O(m) temperature changes such that the tile set uniquely assembles a supertile that precisely encodes the corresponding binary number. As an application, we show how this provides a general tile set of size O(1) that is capable of uniquely assembling essentially any n X n square, where the assembled square is determined by a temperature sequence of length O(log n) that encodes a binary description of n. This yields an important decrease in tile complexity from the required Ω(log n/log log n) for almost all n when the temperature of the system is fixed. We further show that for almost all n, no tile system can simultaneously achieve both o(log n) temperature complexity and O(log n/log log n) tile complexity, showing that both versions of an optimal square building scheme have been discovered. This work suggests that temperature change can constitute a natural, dynamic method for providing input to self-assembly systems that is potentially superior to the current technique of designing large tile sets with specific inputs hardwired into the tileset.
Quasilocal energy for spin-net gravity

The Hamiltonian of the gravitational field defined in a bounded region is quantized. The classical Hamiltonian, and starting point for the regularization, is a boundary term required by functional differentiability of the Hamiltonian constraint. It is the quasilocal energy of the system and becomes the ADM mass in asymptopia. The quantization is carried out within the framework of canonical quantization using spin networks. The result is a gauge-invariant, well-defined operator on the Hilbert space induced by the state space on the whole spatial manifold. The spectrum is computed. An alternative form of the operator, with the correct naive classical limit, but requiring a restriction on the Hilbert space, is also defined. Comparison with earlier work and several consequences are briefly explored.