cssi/SciSciGPT-SciSciNet huggingface dataset:
How Much Do Banks Use Credit Derivatives to Hedge Loans

Before the credit crisis that started in mid-2007, it was generally believed by top regulators that credit derivatives make banks sounder. In this paper, we investigate the validity of this view. We examine the use of credit derivatives by US bank holding companies with assets in excess of one billion dollars from 1999 to 2005. Using the Federal Reserve Bank of Chicago Bank Holding Company Database, we find that in 2005 the gross notional amount of credit derivatives held by banks exceeds the amount of loans on their books. Only 23 large banks out of 395 use credit derivatives and most of their derivatives positions are held for dealer activities rather than for hedging of loans. The net notional amount of credit derivatives used for hedging of loans in 2005 represents less than 2% of the total notional amount of credit derivatives held by banks and less than 2% of their loans. We conclude that the use of credit derivatives by banks to hedge loans is limited because of adverse selection and moral hazard problems and because of the inability of banks to use hedge accounting when hedging with credit derivatives. Our evidence raises important questions about the extent to which the use of credit derivatives makes banks sounder.
Comparable Stocks, Boundedly Rational Stock Markets and IPO Entry Rates

In this study, we examine how initial public offerings (IPO) entry rates are affected when stock markets are boundedly rational and IPO firms infer information from their counterparts in the market. We hypothesize a curvilinear relationship between the number of comparable stocks and initial public offerings (IPO) entry rates into the NASDAQ Stock Exchange. Furthermore, we argue that trading volume and changes in stock returns partially mediates the relationship between the number of comparable stocks and IPO entry rates. The statistical evidence provides strong support for the hypotheses.
Strategies for Choosing Descent Flight-Path Angles for Small Jets

A standard descent procedure with a fixed flight-path angle is proposed to improve trajectory predictability for arriving small jets in the transition airspace into congested terminal area. Three candidate strategies for selecting fuel-efficient and flyable descent flight-path angles are proposed. The three strategies vary in operational complexity and fuel-burn merits. To mitigate variation of wind among flights, the two simpler strategies are adapted to airport, directions of arrival, and time. Three major U.S. airports with different degrees of wind variation and disparate arrival traffic flows are analyzed. Results show that, when compared to the simple airport–static adaptation, the finest adaptation of the simpler strategies recover up to 50–75% of the extra fuel burn relative to the minimum-fuel strategy. Wind variation, descent altitude restrictions, arrival directions, and fleet composition all affect the fuel efficiency of the simple strategies. Tradeoffs between fuel burn and planned speed-brak...
A RAPIDLY SPINNING BLACK HOLE POWERS THE EINSTEIN CROSS

Observations over the past 20 yr have revealed a strong relationship between the properties of the supermassive black hole lying at the center of a galaxy and the host galaxy itself. The magnitude of the spin of the black hole will play a key role in determining the nature of this relationship. To date, direct estimates of black hole spin have been restricted to the local universe. Herein, we present the results of an analysis of ~0.5 Ms of archival Chandra observations of the gravitationally lensed quasar Q 2237+305 (aka the "Einstein-cross"), lying at a redshift of z = 1.695. The boost in flux provided by the gravitational lens allows constraints to be placed on the spin of a black hole at such high redshift for the first time. Utilizing state of the art relativistic disk reflection models, the black hole is found to have a spin of ɑ_* = 0.74^(+0.06)_(-0.03) at the 90% confidence level. Placing a lower limit on the spin, we find a * ≥ 0.65 (4σ). The high value of the spin for the ~10^9 M_☉ black hole in Q 2237+305 lends further support to the coherent accretion scenario for black hole growth. This is the most distant black hole for which the spin has been directly constrained to date.
High Quantum Efficiency AlGaN/GaN Solar-Blind Photodetectors Grown by Metalorganic Chemical Vapor Deposition

We report the growth, fabrication and characterization of high-quality AlGaN/GaN solar-blind p-i-n and MSM photodetectors by low-pressure metalorganic chemical vapor deposition (MOCVD). The epitaxial layers were grown on double-polished c-plane (0001) sapphire substrates to allow for back-side illumination. The p-i-n photodiode structures typically consist of a 0.7 μm thick Al 0.58 Ga 0.42 N window layer, graded to a 0.2 μm thick Al 0.47 Ga 0.53 N n layer, a 0.15 μm thick Al 0.39 Ga 0.61 N i layer, a 0.2 μm thick Al 0.47 Ga 0.53 N p layer, and capped with a 25 nm GaN:Mg contact layer. At a 0 V bias, the processed p-i-n devices exhibit a solar-blind photoresponse having a maximum responsivity of 0.058 A/W at 279 nm, corresponding to an external quantum efficiency of ∼26%, uncorrected for reflections, etc. The MSM devices typically consist of an AIGaN x ∼ 0.58 window layer, and an undoped AlGaN x ∼ 0.44 absorbing layer. The MSMs exhibit an external quantum efficiency as high as ∼47% at a bias of 15 V with a peak response at 262 nm.
Series expansions for excited states of quantum lattice models

We show that by means of connected-graph expansions one can effectively generate exact high-order series expansions which are informative of low-lying excited states for quantum many-body systems defined on a lattice. In particular, the Fourier series coefficients of elementary excitation spectra are directly obtained. The numerical calculations involved are straightforward extensions of those which have already been used to calculate series expansions for ground-state correlations and T = 0 susceptibilities in a wide variety of models.
Benzocyclobutadienyl anion: formation and energetics of an antiaromatic molecule

Benzocyclobutadienyl diazirine (2) was synthesized and reacted with hydroxide ion in a Fourier transform mass spectrometer to afford the conjugate base of benzocyclobutadiene (1a). Authentication of the ion structure was carried out by a derivatization experiment (i.e., 1a was converted to benzocyclobutenone enolate, which has previously been studied), and its reactivity was explored. Thermochemical data for benzocyclobutadiene (1) were obtained (ΔH°acid (1) = 386 ± 3 kcal mol-1, EA(1r) = 1.8 ± 0.1 eV, and C−H BDE (1) = 114 ± 4 kcal mol-1), compared to MP2 and B3LYP calculations, and contrasted to a series of model compounds. Cyclobutadienyl radical appears to be quite different from benzocyclobutadienyl radical (1r) and worth further exploration.
Massive Protoplanetary Disks in the Trapezium Region

We determine the disk mass distribution around 336 stars in the young (~1 Myr) Orion Nebula cluster by imaging a 25 × 25 region in 3 mm continuum emission with the Owens Valley Millimeter Array. For this sample of 336 stars, we observe 3 mm emission above the 3 σ noise level toward 10 sources, six of which have also been detected optically in silhouette against the bright nebular background. In addition, we detect 20 objects in 3 mm continuum emission that do not correspond to known near-IR cluster members. Comparisons of our measured fluxes with longer wavelength observations enable rough separation of dust emission from thermal free-free emission, and we find substantial dust emission toward most objects. For the sample of 10 objects detected at both 3 mm and near-IR wavelengths, eight exhibit substantial dust emission. Excluding the two high-mass stars (θ1 Ori A and the BN object) and assuming a gas-to-dust ratio of 100, we estimate circumstellar masses ranging from 0.13 to 0.39 M☉. For the cluster members not detected at 3 mm, images of individual objects are stacked to constrain the mean 3 mm flux of the ensemble. The average flux is detected at the 3 σ confidence level and implies an average disk mass of 0.005 M☉, comparable to the minimum-mass solar nebula. The percentage of stars in Orion surrounded by disks more massive than ~0.1 M☉ is consistent with the disk mass distribution in Taurus, and we argue that massive disks in Orion do not appear to be truncated through close encounters with high-mass stars. Comparison of the average disk mass and number of massive dusty structures in Orion with similar surveys of the NGC 2024 and IC 348 clusters is used to constrain the evolutionary timescales of massive circumstellar disks in clustered environments.
24-h esophageal pH testing in asthmatics: respiratory symptom correlation with esophageal acid events.

Background Gastroesophageal reflux (GER) may be a trigger for asthma and may be clinically silent. Twenty-four–hour esophageal pH testing accurately diagnoses GER in asthmatics. There are no reports correlating respiratory symptoms with esophageal acid events. This study examines the prevalence and severity of GER in asthmatics with and without reflux symptoms and examines respiratory symptom correlation with esophageal acid. Methods All esophageal manometry and 24-h esophageal pH tests performed were reviewed in asthmatics who met entrance criteria from July 1, 1989, through November 1, 1994. GER was present if esophageal pH tests were abnormal. Results of esophageal tests were compared for asthmatics with reflux symptoms and GER and asthmatics without reflux symptoms and GER. Respiratory symptoms correlated with esophageal acid events if the esophageal pH was Results Of 199 asthmatics who qualified for analysis, 164 (82%) had reflux symptoms. The results of 24-h esophageal pH tests were abnormal in 118 of 164 asthmatics with reflux symptoms (72%), compared with 10 of 35 asthmatics without reflux symptoms (29%). Among asthmatics with GER, 119 of 151 respiratory symptoms (78.8%) were associated with esophageal acid. Seventy-six of 84 reported coughs (90.5%) were associated with esophageal acid. Theophylline did not alter esophageal parameters. Conclusions There is a strong correlation between esophageal acid events and respiratory symptoms in asthmatics with GER. Respiratory symptom correlation with esophageal acid events further supports that GER may be a trigger for asthma.
Novel alkylpolyamine analogues that possess both antitrypanosomal and antimicrosporidial activity

There is no doubt that significant advancements in anti-infective therapy have improved the quality of life in developed nations. However, in underdeveloped countries, there exist major infectious diseases that account for a large portion of global morbidity. Some of these diseases have the potential to become a threat to those living in North America. Tuberculosis claims an estimated 2 million lives each year, and drug-resistant strains originally found in New York and Russia are now being identified in other locations. Malaria, African trypanosomiasis and Leishmaniasis accounted for an additional 1,210,000 deaths in 1999.1 Also of concern is the increasing incidence of opportunistic infections such as those caused by Pneumocystis carinii and strains of Microsporidia. Drug discovery efforts against the diseases mentioned above are limited because infected persons in underdeveloped areas cannot afford even a single course of therapy, or because the infected population represents too small of a drug market. Clearly, there is a need for new antiinfective agents that are potent, nontoxic and inexpensive to manufacture. We recently described the synthesis and evaluation of a small series of (bis)alkylated polyamines that possess promising antitrypanosomal effects in vitro.2 Analogues possessing a 3-3-3 carbon skeleton (Fig. 1), such as BENSpm 1, CPENSpm 2, and CHENSpm 32,3 have significant antitumor effects in vitro and in vivo, but are inactive against cultured trypanosomes. By contrast, analogues with a 3-7-3-carbon skeleton, typified by MDL 27695 4,4 CHE-3-7-3 5,2,3 and bis-CH-3-7-3 62,3 are inactive as antitumor agents, but possess promising antitrypanosomal effects in vitro. We now report second generation compounds in the 3-7-3 series, their biological evaluation as anti-trypanosomal agents, and their activity against Microsporidia in vitro and in vivo. Figure 1 Structures of the biologically active alkylpolyamines 1–6.
Spatial Patterns of Ethnic Integration in the United States

Segregation and diversity measures are meant to reflect extent of integration. Based on population counts gathered for enumeration units, these areal-based measures are sensitive to the spatial scale at which the data are tabulated. They are also not effective in capturing various types of assimilation affected by spatial distance among ethnic groups. This paper proposes to use the multiethnic household as a measure of ethnic integration and social assimilation. Using 1990 Public Use Microdata Samples (PUMS), the percentage of multiethnic households is derived for each state and Public Use Microdata Area (PUMA) to indicate integration. Based upon the results, Hawaii and Alaska have extremely high levels of integration. The west and southwest are more integrated than the rest of the U.S., with the exceptions of Oklahoma and several states along the east coast. The least integrated region includes several Appalachian states. The PUMA-level analysis reveals a great deal of variation in ethnic integration wit...
Matrix-based system reliability method and applications to bridge networks

Using a matrix-based system reliability (MSR) method, one can estimate the probabilities of complex system events by simple matrix calculations. Unlike existing system reliability methods whose complexity depends highly on that of the system event, the MSR method describes any general system event in a simple matrix form and therefore provides a more convenient way of handling the system event and estimating its probability. Even in the case where one has incomplete information on the component probabilities and/or the statistical dependence thereof, the matrix-based framework enables us to estimate the narrowest bounds on the system failure probability by linear programming. This paper presents the MSR method and applies it to a transportation network consisting of bridge structures. The seismic failure probabilities of bridges are estimated by use of the predictive fragility curves developed by a Bayesian methodology based on experimental data and existing deterministic models of the seismic capacity and demand. Using the MSR method, the probability of disconnection between each city/county and a critical facility is estimated. The probability mass function of the number of failed bridges is computed as well. In order to quantify the relative importance of bridges, the MSR method is used to compute the conditional probabilities of bridge failures given that there is at least one city disconnected from the critical facility. The bounds on the probability of disconnection are also obtained for cases with incomplete information.
Ionization in a 1-dimensional dipole model

We study the evolution of a one-dimensional model atom with δ-function binding potential, subjected to a dipole radiation field E(t)x with E(t) a 2π/ω-periodic real-valued function. We prove that when E(t) is a trigonometric polynomial, complete ionization occurs, i.e. the probability of finding the electron in any fixed region goes to zero as t → ∞. For ψ(x, t = 0) compactly supported and general periodic fields, we decompose ψ(x, t) into uniquely defined resonance terms and a remainder. Each resonance is 2π/ω periodic in time and behaves like the exponentially growing Green's function near x = ±∞. The remainder is given by an asymptotic power series in t-1/2 with coefficients varying with x.
Synthesis of (±)-Phloeodictine A1

The antitumor antibiotic phloeodictine A1 (2) has been synthesized by a convergent seven-step route in 8% overall yield. The key step was the Eguchi aza-Wittig reaction of 6 to give 13 followed by a retro Diels-Alder reaction to liberate 5. Addition of 11-dodecenylmagnesium bromide to 5 to give 4b, alkylation with 18b, and deprotection completed the first synthesis of 2.
Edgeworth Expansions for Realized Volatility and Related Estimators

Abstract This paper shows that the asymptotic normal approximation is often insufficiently accurate for volatility estimators based on high frequency data. To remedy this, we derive Edgeworth expansions for such estimators. The expansions are developed in the framework of small-noise asymptotics. The results have application to Cornish–Fisher inversion and help setting intervals more accurately than those relying on normal distribution.
Synthesis of bicyclic and polycyclic alkenes via palladium-catalyzed intramolecular arylation and vinylation

Abstract Cyclic alkenes containing aryl and vinylic halides undergo facile, palladium-catalyzed cyclization to afford a wide variety of bicyclic and polycyclic alkenes.
The Chief Justice as Executive: Judicial Conference Committee Appointments

AbstractThis article is the first comprehensive empirical study of chief justice appointments to the Judicial Conference committees of the US Courts, entities with influence over substantive public and legal policy. Using a newly created database of all judges appointed to serve on Judicial Conference committees between 1986 and 2012, the results indicate that a judge’s partisan alignment with the chief justice matters, as do personal characteristics such as race, experience on the bench, and court level. These results support claims that Judicial Conference committee selection, membership, and participation may present a vehicle for advancing the chief justice’s individual political and policy interests.
Nuclear physics from lattice QCD

I present a pedagogical overview of the application of lattice QCD to the physics of multi-hadron systems. This is a relatively new area of research in which progress has been significant in the last few years and the aim of these lectures is to provide a perspective on the current and future scope of this emerging frontier. After reviewing the recent developments that are beginning to enable nuclear physics to be studied from the underlying theory of the Standard Model, I discuss the recent results that have been obtained in the study of two-hadron and multi-hadron systems. I also explore the difficulties particular to lattice QCD calculations of such systems and emphasise the issues that remain to be resolved.
Traffic driven resource allocation in heterogenous wireless networks

Most work on wireless network resource allocation use physical layer performance such as sum rate and outage probability as the figure of merit. These metrics may not reflect the true user QoS in future heterogenous networks (HetNets) with many small cells, due to large traffic variations in overlapping cells with complicated interference conditions. This paper studies the spectrum allocation problem in HetNets using the average packet sojourn time as the performance metric. To be specific, in a HetNet with K base terminal stations (BTS's), we determine the optimal partition of the spectrum into 2K possible spectrum sharing combinations. We use an interactive queueing model to characterize the flow level performance, where the service rates are decided by the spectrum partition. The spectrum allocation problem is formulated using a conservative approximation, which makes the optimization problem convex. We prove that in the optimal solution the spectrum is divided into at most K pieces. A numerical algorithm is provided to solve the spectrum allocation problem on a slow timescale with aggregate traffic and service information. Simulation results show that the proposed solution achieves significant gains compared to both orthogonal and full spectrum reuse allocations with moderate to heavy traffic.
Design Considerations for Very High Frequency Resonant Mode DC/DC Converters

The demand for higher switching frequencies in power converters has rekindled interest in resonant mode topologies. Conventional resonant converter circuits, however, are not optimized for high-frequency operation. A new resonant mode dc/dc converter topology exhibits desirable characteristics including zero switching losses, elimination of snubbers, simple control strategy, and circuit operation that is insensitive to parasitics such as diode reverse recovery. Analysis and design techniques are discussed in detail and are experimentally verified with a 150-W prototype converter operating in the frequency range 500 kHz-1 MHz.
Endomorphisms of the shift dynamical system, discrete derivatives, and applications

All continuous endomorphisms f"~ of the shift dynamical system S on the 2-adic integers Z"2 are induced by some f:B"n->{0,1}, where n is a positive integer, B"n is the set of n-blocks over {0, 1}, and f"~(x)=y"0y"1y"2... where for all i@?N, y"i=f(x"ix"i"+"1...x"i"+"n"-"1). Define D:Z"2->Z"2 to be the endomorphism of S induced by the map {(00,0),(01,1),(10,1),(11,0)} and V:Z"2->Z"2 by V(x)=-1-x. We prove that D, V@?D, S, and V@?S are conjugate to S and are the only continuous endomorphisms of S whose parity vector function is solenoidal. We investigate the properties of D as a dynamical system, and use D to construct a conjugacy from the 3x+1 function T:Z"2->Z"2 to a parity-neutral dynamical system. We also construct a conjugacy R from D to T. We apply these results to establish that, in order to prove the 3x+1 conjecture, it suffices to show that for any m@?Z^+, there exists some n@?N such that R^-^1(m) has binary representation of the form x"0x"1...x"2"^"n"-"1@? or x"0x"1x"2...x"2"^"n@?.
Disparate quasiballistic heat conduction regimes from periodic heat sources on a substrate

We report disparate quasiballistic heat conduction trends for periodic nanoscale line heaters deposited on a substrate, depending upon whether measurements are based on the peak temperature of the heaters or the temperature difference between the peak and the valley of two neighboring heaters. The degree of quasiballistic transport is characterized by the effective thermal conductivities of the substrate which are obtained by matching the diffusion solutions to the phonon Boltzmann transport equation results. We find that while the ballistic heat conduction effect based on the peak temperature diminishes as the two heaters become closer, it becomes stronger based on the peak-valley temperature difference. Our results also show that the collective behavior of closely spaced heaters can counteract the nonlocal effects caused by an isolated nanoscale hot spot. These results are relevant to thermal conductivity spectroscopy techniques under development and also have important implications for understanding nonlocal heat conduction in integrated circuits and carbon nanotube array thermal interface materials.
Coherent Sheaves on Configuration Schemes

Abstract We introduce and study configuration schemes , which are obtained by “glueing” usual schemes along closed embeddings. The category of coherent sheaves on a configuration scheme is investigated. Smooth configuration schemes provide alternative “resolutions of singularities” of usual singular schemes. We consider in detail the case when the singular scheme is a union of hyperplanes in a projective space.
Optimistic parallelism requires abstractions

The problem of writing software for multicore processors is greatly simplified if we could automatically parallelize sequential programs. Although auto-parallelization has been studied for many decades, it has succeeded only in a few application areas such as dense matrix computations. In particular, auto-parallelization of irregular programs, which are organized around large, pointer-based data structures like graphs, has seemed intractable.The Galois project is taking a fresh look at autoparallelization. Rather than attempt to parallelize all programs no matter how obscurely they are written, we are designing programming abstractions that permit programmers to highlight opportunities for exploiting parallelism in sequential programs, and building a runtime system that uses these hints to execute the program in parallel. In this paper, we describe the design and implementation of a system based on these ideas. Experimental results for two real-world irregular applications, a Delaunay mesh refinement application and a graphics application that performs agglomerative clustering, demonstrate that this approach is promising.
The absence of molybdenum precursor effects for methanol oxidation over molybdenum oxide supported on silica

Abstract The partial oxidation of methanol to formaldehyde and methyl formate has been studied at low conversion over Mo/SiO 2 . Catalysts up to 1.1 wt% Mo were prepared from MoCl 5 , Mo 2 (η 3 -C 3 H 5 ) 4 , and (NH 4 ) 6 Mo 7 O 24 · 4H 2 O. Fumed silica (Cab-O-Sil EH-5), silica gel (Davison 952 and Rhone-Poulenc XOA-400), and Davison 952 silica, washed in acid to remove calcium, were used as supports. Iron-doped Cab-O-Sil was also used. Over identical supports, the activity and selectivity of methanol oxidation was similar for samples prepared from all precursors, although some slight differences were observed. More significant differences were observed, however, when the impurity levels were changed by acid washing, iron doping, and using different types of silica. The results suggest that impurities on the silica support, rather than the method of preparation or precursor, have a greater influence on methanol oxidation selectivity for loadings less than 1.1 wt% Mo metal.
Wilson lines and symmetry breaking on orbifolds

Gauge symmetry breaking by boundary conditions on a manifold is known to be equivalent to Wilson-line breaking through a background gauge field, and is therefore spontaneous. These equivalent pictures are related by a non-periodic gauge transformation. However, we find that boundary condition gauge symmetry breaking on orbifolds is explicit; there is no gauge where all the breaking can be attributed to a background gauge field. In the case of a five-dimensional SU(5) grand unified theory on S{sup 1} = Z{sub 2}, the vacuum with gauge symmetry broken to SU(3) x SU(2) x U(1) and that with SU(5) preserved are completely disconnected: there is no physical process which causes tunneling between the two. This allows a certain localized explicit breaking of SU(5) on one of the orbifold fixed points in the theory with SU(5) breaking. Split multiplets on this fixed point are shown not to induce violations of unitarity in scattering amplitudes.
Optimal Expectations and Limited Medical Testing: Evidence from Huntington Disease

Abstract We use novel data to study genetic testing among individuals at risk for Huntington disease (HD), a hereditary disease with limited life expectancy. Although genetic testing is perfectly predictive and carries little economic cost, presymptomatic testing is rare. Testing rates increase with increases in ex ante risk of having HD. Untested individuals express optimistic beliefs about their health and make decisions (e.g., retirement) as if they do not have HD, even though individuals with confirmed HD behave differently. We suggest that these facts can be reconciled by an optimal expectations model (Brunnermeier and Parker 2005). (JEL D84, I12)
Resolutions, recoveries and relationships: The evolution of payment disputes in Central and Eastern Europe

Abstract In this article, we use a survey of small and medium-sized manufacturing enterprises in three Central and East European countries to investigate the resolution of commercial disputes and the ability of aggrieved parties to recover damages. The evidence suggests that the spatial relationship of the disputants and the claimant's membership in a business association are important to the outcomes. These findings complement results regarding the costs of transacting and market evolution in other contexts. Specifically, greater geographic distance between trade partners is associated with greater transaction costs that can be attenuated by non-public institutions that facilitate information exchange. Journal of Comparative Economics 34 (2) (2006) 317–337.
Fetal breathing movements in pregnancies complicated by premature membrane rupture in the second trimester.

Abstract Forty pregnancies complicated by oligohydramnios in the second trimester due to prolonged and premature membrane rupture (PPROM) were followed prospectively to determine factors influencing fetal breathing activity and the relationship of fetal breathing movements (FBM) to outcome. The patients were retrospectively divided into three groups according to the presence or absence of FBM. Membrane rupture occurred at a significantly earlier gestation in those pregnancies in which FBM were absent. Duration of membrane rupture only differed significantly between pregnancies in which FBM were intermittent or consistently present. In the group in which FBM were always absent ( N = 12) all the infants died in utero or in the neonatal period due to pulmonary hypoplasia. In the group with FBM always present ( N = 17) all infants survived. In the third group FBM were observed in some, but not all, ultrasound examinations ( N = 11). Some infants survived ( N = 6), while others died either due to pulmonary hypoplasia or neonatal sepsis. These results show the necessity for several serial ultrasound examinations, all demonstrating the absence of fetal breathing movements, before pulmonary hypoplasia in PPROM can be predicted confidently.
Structure and Energetics of LiBH4 and Its Surfaces: A First-Principles Study†

The structure and energetics of LiBH4 and its surfaces have been studied using the density functional theory (DFT) plane-wave method. The DFT relaxed bulk LiBH4 structure is in agreement with the synchrotron X-ray diffraction results. Four low-index surfaces, (100), (010), (001), and (101), have been created from the relaxed bulk structure. The (010), (100), and (101) surfaces were found to have a similar surface energy, ∼0.12 J/m2, and are significantly more stable than the (001) surface. The H vacancy formation energies on the low-energy surfaces have been found in a narrow range of 180−200 kJ/mol. The formation energy for the first H vacancy on the (001) surface is 165.8 kJ/mol and is the lowest among all the surfaces.
Effects of interface structure on the electrical characteristics of PtSi-Si Schottky barrier contacts

Abstract The properties of PtSiSi Schottky barrier contacts formed by a new technique employing multilayer metallization are compared with those of contacts prepared by the conventional single-layer metallization method. The multilayer technique permits the formation of very shallow contacts without any limitation being placed on the thickness of the PtSi layer. For a PtSi layer of given thickness the PtSi-Si contact interface obtained by this technique is more uniform than the interface formed by annealing a single layer of platinum on silicon. The interfacial uniformity is independent of PtSi thickness for shallow PtSiSi contacts produced by the multilayer technique, while for conventional contacts the uniformity decreases with increasing PtSi thickness. Large-area (9.4 × 10 -3 cm 2 ) diodes utilizing shallow PtSiSi contacts about 200 A deep have been fabricated without guard rings. These diodes exhibit near-ideal forward current-voltage characteristics, low reverse leakage currents (less than 5 nA at -10 V) and high breakdown voltages (over -90 V). These characteristics are superior to those of diodes using conventional PtSi-Si contacts.
Non-abelian anomalies and effective actions for a homogeneous space G/ H

Abstract We consider the problem of constructing the fully gauged effective action in 2 n -dimensional space-time for Nambu-Goldstone bosons valued in a homogeneous space G / H , with the requirement that the action is a solution of the anomalous Ward identity and that it is invariant under the gauge transformations of H . We show that this can be done whenever the homotopy group , π 2 n ( G / H ) is trivial, G / H is reductive and H is embedded in G so as to be anomaly free, in particular when H is an anomaly safe group. We construct the necessary generalization of the Bardeen counterterm and give explicit forms for the anomaly and the effective action. When G / H is a symmetric space, the counterterm and the anomaly decompose into a parity-even and a parity-odd part. In this case, for the parity-even part of the action, one does not need the anomaly free embedding of H .
Calibration of Nebular Emission-Line Diagnostics. II. Abundances

We examine standard methods of measuring nebular chemical abundances, including estimates based on direct Te measurements and also emission-line diagnostics. We use observations of the LMC H II regions DEM L199, DEM L243, DEM L301, and DEM L323, the ionizing stars of which have classifications ranging from O7 to WN3. Following common practice, we assume a two-zone Te structure given by T(O++) and T(O+) to compute ionic abundances. We compare with photoionization models tailored to the observed properties of the individual objects, and we emphasize the importance of correctly relating Te in the two zones, which can otherwise cause errors of ~0.2 dex in abundance estimates. The data show no spatial variations or local metallicity enhancements to within 0.1-0.15 dex in any of the objects, notably including DEM L199, which hosts three Wolf-Rayet stars. Our data agree well with both the modeled R23 and S23 abundance diagnostics for O and S. We present the first theoretical tracks for S23, which are in excellent agreement with a larger available data set. However, contrary to earlier suggestions, S23 is much more sensitive to the ionization parameter (U) than is R23. This occurs because S23 does not sample S IV, which is often a significant population. We therefore introduce S234 ≡ ([S II] + [S III] + [S IV])/Hβ and demonstrate that it is virtually independent of U. Predicted and observed spatial variations in S234 are thus dramatically decreased in contrast to S23. The intensity of [S IV] 10.5 μm can be easily estimated from the simple correspondence between [S IV]/[S III] and [O III]/[O II]. Using this method to estimate S234 for data in the literature yields excellent agreement with our model tracks, hence we give a theoretical calibration for S234. Our models show that the double-valued structure of S23 and S234 remains an important problem as for R23, and, at present, we consider calibrations of these S diagnostics reliable only at Z 0.5 Z☉. However, the slightly larger dynamic range and excellent compatibility with theoretical predictions suggest the S parameters to be more effective abundance diagnostics than R23.
Pediatric cholesteatoma: a retrospective review.

Summary Objectives The optimal treatment for pediatric cholesteatoma is controversial. Management decisions including intact canal wall versus open cavity techniques, second look procedures and staging ossicular reconstruction continue to be debated. In an attempt to clarify this issue we conducted an 11-year retrospective analysis of our experience with cholesteatoma presenting in our pediatric population. Study design Retrospective review of children undergoing surgical intervention for cholesteatoma at a tertiary care pediatric hospital between 1 July 1992 and 1 July 2003 by the senior author. Methods Comparison of recurrence rates in intact canal wall (ICW) versus canal wall down (CWD) procedures; with analysis of second-look procedures, ossicular chain reconstruction (OCR) and hearing results in the management of pediatric cholesteatoma. Results Two hundred and sixty-two children with 278 cases of cholesteatoma underwent surgical resection. Of these children, 221 were managed via an ICW approach while the remaining 57 underwent a CWD procedure. The overall recurrence rate in this series was 16%, with 17% in the ICW group and 12% in the CWD group. OCR was performed in 97% of the ICW cases at time of second-look procedure, with 75% undergoing reconstruction with partial ossicular reconstruction prosthesis. The average air-bone gap improvement in these patients was 10.8 dB, with an average hearing improvement of total ossicular reconstruction of 5.8 dB. The average hearing improvement in the CWD group, all managed with cartilage interposition grafts, was 3.7 dB. Conclusions Management of pediatric cholesteatoma requires a highly individualized approach that takes into account anatomic, clinical and social factors to determine the most successful surgical treatment paradigm.
ESTIMATING ELECTRIC FIELDS FROM VECTOR MAGNETOGRAM SEQUENCES

Determining the electric field distribution on the Sun's photosphere is essential for quantitative studies of how energy flows from the Sun's photosphere, through the corona, and into the heliosphere. This electric field also provides valuable input for data-driven models of the solar atmosphere and the Sun-Earth system. We show how observed vector magnetogram time series can be used to estimate the photospheric electric field. Our method uses a "poloidal-toroidal decomposition" (PTD) of the time derivative of the vector magnetic field. These solutions provide an electric field whose curl obeys all three components of Faraday's Law. The PTD solutions are not unique; the gradient of a scalar potential can be added to the PTD electric field without affecting consistency with Faraday's Law. We then present an iterative technique to determine a potential function consistent with ideal MHD evolution; but this field is also not a unique solution to Faraday's Law. Finally, we explore a variational approach that minimizes an energy functional to determine a unique electric field, a generalization of Longcope's "Minimum Energy Fit." The PTD technique, the iterative technique, and the variational technique are used to estimate electric fields from a pair of synthetic vector magnetograms taken from an MHD simulation; and these fields are compared with the simulation's known electric fields. The PTD and iteration techniques compare favorably to results from existing velocity inversion techniques. These three techniques are then applied to a pair of vector magnetograms of solar active region NOAA AR8210, to demonstrate the methods with real data. Careful examination of the results from all three methods indicates that evolution of the magnetic vector by itself does not provide enough information to determine the true electric field in the photosphere. Either more information from other measurements, or physical constraints other than those considered here are necessary to find the true electric field. However, we show it is possible to construct physically reasonable electric field distributions whose curl matches the evolution of all three components of B. We also show that the horizontal and vertical Poynting flux patterns derived from the three techniques are similar to one another for the cases investigated.
The Direct and Enantioselective Organocatalytic α-Oxidation of Aldehydes

The first direct enantioselective catalytic α-oxidation of carbonyls has been accomplished. The use of enamine catalysis has provided a new organocatalytic strategy for the enantioselective oxyamination of aldehydes, to generate α-oxyaldehydes, important chiral synthons for natural product and medicinal agent synthesis. The use of l-proline as the asymmetric catalyst has been found to mediate the oxidation of a large variety of aldehyde substrates with nitrosobenzene serving as the electrophilic oxidant. A diverse spectrum of aldehyde substrates can also be accommodated in this new organocatalytic transformation. While catalyst quantities of 2 mol % were generally employed in this study, successful oxidations conducted using catalyst loadings as low as 0.5 mol % are described.
Judicial Legitimacy as a Repeated Game

An independent judiciary faces the problem of how to restrain high-court judges from indulging their personal whims. One restraint is the desire of judges to influence future judges. To do so, judges may have to maintain their own or the system's legitimacy by restraining their own behavior. This situation can be viewed as an equilibrium of an infinitely repeated game. Such a game has many equilibria, some of which are Pareto superior to others. In some equilibria, self-interested judges are responsible even without the threat of external penalties. Copyright 1994 by Oxford University Press.
Testing flatness of the universe with probes of cosmic distances and growth

When using distance measurements to probe spatial curvature, the geometric degeneracy between curvature and dark energy in the distance-redshift relation typically requires either making strong assumptions about the dark energy evolution or sacrificing precision in a more model-independent approach. Measurements of the redshift evolution of the linear growth of perturbations can break the geometric degeneracy, providing curvature constraints that are both precise and model independent. Future supernova, CMB, and cluster data have the potential to measure the curvature with an accuracy of $\ensuremath{\sigma}({\ensuremath{\Omega}}_{K})=0.002$, without specifying a particular dark energy phenomenology. In combination with distance measurements, the evolution of the growth function at low redshifts provides the strongest curvature constraint if the high-redshift universe is well approximated as being purely matter dominated. However, in the presence of early dark energy or massive neutrinos, the precision in curvature is reduced due to additional degeneracies, and precise normalization of the growth function relative to recombination is important for obtaining accurate constraints. Curvature limits from distances and growth compare favorably to other approaches to curvature estimation proposed in the literature, providing either greater accuracy or greater freedom from dark energy modeling assumptions, and are complementary due to the use of independent data sets. Model-independent estimates of curvature are critical both for testing inflation and for obtaining unbiased constraints on dark energy parameters.
Ab initio investigation of hydrogen bonding by carbamates: Complexes including N-methyl methylcarbamate, N-phenyl methylcarbamate, dimethyl ether and methyl acetate

Abstract Hydrogen bonds of the type NH··O which occur in interactions between N-methyl methyl carbamate or N-phenyl methylearbamate and (i) a second carbamate, (ii) an ester, and (iii) an ether are studied by ab initio methods using a minimal MINI-1 basis set. Of the three, the ether forms the strongest complex with a carbamate. Replacement of the methyl group bonded to the proton-donating N of the carbamate by a phenyl group leads to a somewhat stronger H-bond in all cases. The electron density patterns are typical of rearrangements that normally accompany H-bond formation.
Intertemporal Tax Discontinuities

We define an intertemporal tax discontinuity (ITD) as a circumstance in which different tax rates are applied to gains realized at one point in time versus some other point in time. We study the effects of ITDs on market behaviors at the time of disclosures of firm performance, assuming that all investors who trade firm equities are subject to tax. The results of our paper suggest that relative to an economy in which ITDs are absent, ITDs may dampen trading volume and amplify price changes at the time of disclosure.
Statistical Extrapolation Methods for Estimating Wind Turbine Extreme Loads

*† rd edition of the International Electrotechnical Commission (IEC) Standard 61400-1, designers of wind turbines are now explicitly required, in one of the prescribed load cases, to use statistical extrapolation techniques to determine nominal design loads. In this study, we use field data from a utility-scale 1.5MW turbine sited in Lamar, Colorado to compare the performance of several alternative techniques for statistical extrapolation of rotor and tower loads—these include the method of global maxima, the peak-over-threshold method, and a four-moment process model approach. Using each of these three options, fifty-year return loads are estimated for the selected wind turbine. We conclude that the peak-over-threshold method is the superior approach, and we examine important details intrinsic to this method, including selection of the level of the threshold to be employed, the parametric distribution used in fitting, and the assumption of statistical independence between successive peaks. While we are primarily interested in the prediction of extreme loads, we are also interested in assessing the uncertainty in our predictions as a function of the amount of data used. Towards this end, we first obtain estimates of extreme loads associated with target reliability levels by making use of all of the data available, and then we obtain similar estimates using only subsets of the data. From these separate estimates, conclusions are made regarding what constitutes a sufficient amount of data upon which to base a statistical extrapolation. While this study makes use of field data in addressing statistical load extrapolation issues, the findings should also be useful in simulation-based attempts at deriving wind turbine design load levels where similar questions regarding extrapolation techniques, distribution choices, and amount of data needed are just as relevant.
Tailoring effective exchange interactions via domain walls in coupled Heisenberg rings

The nature of the exchange coupling variation in an antiferromagnetic spin-$\frac{1}{2}$ system can be used to tailor its ground-state properties. In particular, dimerized Heisenberg rings containing domain walls have localized states that can serve as ``flying spin qubits'' when the domain walls are moved. We show theoretically that when two of these rings are coupled, the movement of the domain walls leads to modulation of the effective exchange interaction between the qubits. Appropriately chosen configurations of domain walls can give rise to ferromagnetic effective exchange. We describe how these spin rings may be used as basic building blocks to construct quantum spin systems whose properties are tunable by virtue of the exchange variation within the rings.
"Polysiloxane-Pd" nanocomposites as recyclable chemoselective hydrogenation catalysts.

Polysiloxane-encapsulated “Pd”-nanoclusters were generated by reduction of Pd(OAc)2 with polymethylhydrosiloxane, which functions as a reducing agent as well as a capping material for production and stabilization of catalytically active “Pd”-nanoparticles. Chemoselective hydrogenation of functional conjugated alkenes was achieved by in-situ- or ex-situ-generated polysiloxane-stabilized “Pd”-nanoclusters under mild reaction conditions in high yields. Electron microscopy, UV−vis, and NMR studies of the reaction mixture during the catalytic transformation were performed and, in conjunction with catalyst poisoning experiments, demonstrated unequivocally the role of polysiloxane-encapsulated “Pd”-nanoclusters as the real catalytic species. The recyclability of the “Pd”-nanoclusters was established by reusing the solid left after the reaction.
A Follow-up Study of the Relationships among Trust, Disclosure, and Interpersonal Solidarity

This study conceptualized perceived trustworthiness of the individual, self-disclosure to the individual, perceived trustworthiness of people in general, and disclosive tendencies to other people in general to be indicants of a broader construct of trust. Self-disclosure and perceived trustworthiness of the individual were found to be related constructs assessing differential aspects of the trust construct. Likewise, self-disclosure and perceived trustworthiness of the individual were found to be criterial attributes of interpersonal solidarity. These communication-related phenomena indicated the solidarity of interpersonal relationships. In the progress of the research, a 20-item measure of perceived interpersonal solidarity was developed as a criterion for assessing the impact of communication-related variables on interpersonal relationships. Other exploratory research issues were investigated.