cssi/SciSciGPT-SciSciNet huggingface dataset:
THE PICARD GROUP OF THE LOOP SPACE OF THE RIEMANN SPHERE

The loop space Lℙ1 of the Riemann sphere consisting of all Ck or Sobolev Wk, p maps S1 → ℙ1 is an infinite dimensional complex manifold. We compute the Picard group pic(Lℙ1) of holomorphic line bundles on Lℙ1 as an infinite dimensional complex Lie group with Lie algebra the Dolbeault group H0, 1(Lℙ1). The group G of Mobius transformations and its loop group LG act on Lℙ1. We prove that an element of pic(Lℙ1) is LG-fixed if it is G-fixed, thus completely answering the question of Millson and Zombro about the G-equivariant projective embedding of Lℙ1.
The hard X-rays and gamma rays from solar flares

Radiation of energies from 10 KeV to greater than 10 MeV has been observed during solar flares, and is interpreted to be due to bremsstrahlung by relativistic electrons. A complete treatment of this problem requires solution of the kinetic equation for relativistic electrons and inclusion of synchrotron energy losses. Using the electron distributions obtained from numerical solutions of this equation the bremsstrahlung spectra in the impulsive x ray and gamma-ray regimes are calculated, and the variation of these spectral indices and directivities with energy and observation angle are described. The dependences of these characteristics of the radiation of changes in the solar atmospheric model, including the convergence of the magnetic field, the injected electron spectral index, and most importantly, in the anisotropy of the injected electrons and of the convergence of the magnetic field are also described. The model results are compared with stereoscopic observations of individual flares and the constraints that this data sets on the models are discussed.
A zwitterionic zirconium complex that catalyzes hydroamination of aminoalkenes at room temperature

The zwitterionic cyclopentadienyl-bis(2-oxazolinyl)borate diamidozirconium(IV) complex is a precatalyst for the cyclization of aminoalkenes to five- and six-membered rings under mild conditions.
Heat Exchanger Analysis Modified to Account for a Heat Source

A modified heat exchanger analysis is developed here that accounts for a heat source, which is assumed to be volumetrically uniform in the hot fluid. The motivation for this work arises from the analysis of an ammonia-water absorber heat exchanger where a heat-of-absorption source term arises in the solution side. Utility of the analysis in deducing the overall heat transfer coefficient from experimental measurements is demonstrated.
QUANTIFYING AND MANAGING RISK IN AGRICULTURE

ABSTRACT The purpose of this paper is to review relevant portions of the risk literature and propose an agenda of applied risk research. More specifically, the paper discusses the major sources of risk in agriculture, summarizes several methods of quantifying risk, summarizes the literature on estimates of agricultural producers' risk preferences, and briefly discusses alternative methods to manage risk. The applied research agenda given in the final section is included to promote discussion of ways that we can aid decision makers apply what has been learned. The discussion focuses on these topics as they relate to agricultural producing units. Many of the same procedures can be applied to firms in processing and distribution as well as to the analysis of aggregate policy issues. The comments are developed from experience, primarily in the United States, and based on work in other areas of the world.
Disparate adjuvant properties among three formulations of "alum".

Aluminum adjuvants, commonly referred to as “alum,” are the most widespread immunostimulants in human vaccines. Although the mechanisms that promote humoral responses to alum-adsorbed antigens are still enigmatic, alum is thought to form antigen depots and induce inflammatory signals that, in turn, promote antibody production. It was recently noted that Imject® alum, a commercial aluminum-containing adjuvant commonly used in animal studies, is not the physicochemical equivalent of aluminum adjuvant present in human vaccines. This difference raises concerns about the use of Imject® alum in animal research as a model for approved aluminum adjuvants. Here, we compared the capacity of Imject® alum, Alhydrogel®, and a traditional alum-antigen precipitate to induce humoral responses in mice to the hapten-carrier antigen, NP-CGG [(4-hydroxy-3-nitrophenyl)acetyl-chicken γ-globulin]. The magnitude of humoral responses elicited by Alhydrogel® and precipitated alum was significantly greater than that induced by Imject® alum. The strength of the humoral responses elicited by different alum formulations was correlated with the quantity of pro-inflammatory cytokines induced and the numbers of inflammatory cells at the site of immunization. Moreover, Imject® exhibited a severely reduced capacity to adsorb protein antigens compared to Alhydrogel® and precipitated alum. These findings reveal substantial differences in the immunostimulatory properties of distinct alum preparations, an important point of consideration for the evaluation of novel adjuvants, the assessment of new alum-based vaccines, and in mechanistic studies of adjuvanticity.
Congruences for Broken k-Diamond Partitions

We prove two conjectures of Paule and Radu from their recent paper on broken k-diamond partitions.
Making Weirdness Work: Quantum Information and Computation

Information is something that can be encoded in the state of a physical system, and a computation is a task that can be performed with a physically realizable device. Therefore, since the physical world is fundamentally quantum mechanical, the foundations of information theory and computer science should be sought in quantum physics. In fact, quantum information has weird properties that contrast sharply with the familiar properties of classical information. A quantum computer - a new type of machine that exploits the quantum properties of information - could perform certain types of calculations far more efficiently than any foreseeable classical computer. To build a functional quantum computer will be an enormous technical challenge. New methods for quantum error correction are being developed that can help to prevent a quantum computer from crashing
Building Bridges in Catalysis Science. Monodispersed Metallic Nanoparticles for Homogeneous Catalysis and Atomic Scale Characterization of Catalysts Under Reaction Conditions

The reactivity of small (<1.5 nm), highly oxidized metallic nanoparticles and the utilization of Sum Frequency Generation spectroscopy (SFG) and Scanning Tunneling Microscopy (STM) for investigations of catalysts under reaction conditions are discussed in this review paper. Batch and flow reactor studies were carried out using highly oxidized 40 atom clusters (Pt, Pd and Rh) to measure reaction rate and product distribution of electrophilic reactions, using toluene as a solvent. These heterogeneous catalysts show reactivity which is similar and sometimes even higher than the homogeneous catalysts. The combination of an in situ SFG and STM measurements facilitate a detection of the surface structure and reaction intermediates under reaction conditions. While the STM detects the surface reconstruction and the mobility of products and reactants molecules, the SFG can correlate the reactivity and more importantly the selectivity, to the active surface intermediates. The recent developments in these two research areas are detailed in this review paper.
LEGISLATIVE TURNOVER, FISCAL POLICY, AND ECONOMIC GROWTH: EVIDENCE FROM U.S. STATE LEGISLATURES

An examination of how increased turnover among legislators in the fifty U.S. states affects fiscal policy and economic growth finds that it makes legislators short-sighted. Turnover increases the size of government by increasing the shares of both total spending and taxes in income. In particular, turnover increases capital expenditure and income taxes, both of which may cause long-run distortions in the economy. Further, increased turnover, by resulting in inefficient fiscal policy, reduces long-term economic growth.
Heat and entropy in nonextensive thermodynamics

The concepts of the “quantity of heat” and “work” are deduced in the context of non-extensive statistical mechanics, following steps parallel to those employed in extensive statistical mechanics.
Synthesis of diastereomerically and enantiomerically pure 2,3-disubstituted tetrahydrofurans using a sulfoxonium ylide

Nucleophilic substitution reactions of 2,3-epoxy alcohols, easily prepared via Sharpless asymmetric epoxidation chemistry, offer access to a wide variety of enantiomerically pure compounds. In this communication, we describe the use of a Payne rearrangement to control regioselectivity in the ring-opening of a series of 2,3-epoxy alcohols with dimethylsulfoxonium methylide to yield diastereomerically and/or enantiomerically pure disubstituted tetrahydrofuran rings. The factors influencing the success and substitution pattern of the THF ring products are discussed, including steric, electronic, and solvent effects.
Radical Cyclizations of Cyclic Ene Sulfonamides Occur with β-Elimination of Sulfonyl Radicals to Form Polycyclic Imines

Radical cyclizations of cyclic ene sulfonamides provide stable bicyclic and tricyclic aldimines and ketimines in good yields. Depending on the structure of the precursor, the cyclizations occur to provide fused and spirocyclic imines with five-, six-, and seven-membered rings. The initial radical cyclization produces an α-sulfonamidoyl radical that undergoes elimination to form the imine and a phenylsulfonyl radical. In a related method, 3,4-dihydroquinolines can also be produced by radical translocation reactions of N-(2-iodophenylsulfonyl)tetrahydroiso-quinolines. In either case, very stable sulfonamides are cleaved to form imines (rather than amines) under mild reductive conditions.
Resonance scattering on the lattice with non-zero total momentum

Most hadronic particles are resonances: for example, the ρ meson appears as a resonance in the elastic scattering of two pions. A method by Luscher enables one to measure the properties of the resonance particles from finite lattices. We present a more general method which includes scattering processes where the total momentum of the particles is non-zero. The main advantage is that the resonance scattering can be observed in a considerably smaller spatial volume. We test the method with a simple 3+1 dimensional spin model, and find excellent agreement between the zero momentum and the non-zero momentum scattering sectors.
Rotational spectrum and structure of the OCS–(CO2)2 trimer

The rotational spectra of seven isotopes of the CO2−(OCS)2 mixed trimer have been assigned using pulsed nozzle FTMW spectroscopy techniques. The structure resembles a distorted triangular cylinder with the three monomers aligned roughly parallel. The trimer may be thought of as a slightly perturbed (OCS)2 dimer with the CO2 lying above the dimer and crossed at 12° and 20° to the axes of the two OCS molecules, respectively. The distance between the carbon atoms on the OCS is 3.757(9) A. The distance between the carbon on each OCS and the carbon on the CO2 is 3.574(6) and 3.773(8) A, respectively. The dipole moment components for the trimer are μa = 0.40(1) D, μb = 0.21(7) D, and μc = 0.206(1) D with μtotal = 0.50(4) D. The structure and dipole moments are close to those predicted by an interaction model which includes a distributed multipole moment electrostatic contribution and atom−atom terms to describe the dispersion and repulsion interactions.
Synthetic chemistry-led creation of a difluorinated biaryl ether non-nucleoside reverse transcriptase inhibitor

In the process of developing a series of novel, fluorinated biaryl ether NNRTIs, we fortuitously discovered derivative 20, which possesses excellent potency against both wild-type and clinically relevant mutations of the reverse transcriptase enzyme.
Reconstruction threshold for the hardcore model

In this paper we consider the reconstruction problem on the tree for the hardcore model. We determine new bounds for the nonreconstruction regime on the k-regular tree showing nonreconstruction when λ (e+o(1)) ln2 k. We discuss the relationship for finding large independent sets in sparse random graphs and to the mixing time of Markov chains for sampling independent sets on trees.
Supernova neutrinos, giant resonances, and nucleosynthesis

Abstract Almost all of the 3 · 10 53 ergs liberated in a core collapse supernova is radiated as neutrinos by the cooling neutron star. These neutrinos can excite nuclei in the mantle of the star by their neutral and charged current reactions. I argue that the resulting spallation reactions are an important nucleosynthesis mechanism that may be responsible for the galactic abundances of 7 Li, 11 B, 19 F, 138 La, 180 Ta and approximately a dozen other light nuclei.
Degree complexity of birational maps related to matrix inversion: symmetric case

For q ≥ 3, we let \({\mathcal{S}_q}\) denote the projectivization of the set of symmetric q × q matrices with coefficients in \({\mathbb{C}}\). We let \({I(x)=(x_{i,j})^{-1}}\) denote the matrix inverse, and we let \({J(x)=(x_{i,j}^{-1})}\) be the matrix whose entries are the reciprocals of the entries of x. We let \({K|\mathcal{S}_q=I\circ J:~\mathcal{S}_q\rightarrow \mathcal{S}_q}\) denote the restriction of the composition I ◦ J to \({\mathcal{S}_q}\). This is a birational map whose properties have attracted some attention in statistical mechanics. In this paper we compute the degree complexity of \({K|\mathcal{S}_q}\), thus confirming a conjecture of Angles d’Auriac et al. (J Phys A Math Gen 39:3641–3654, 2006).
Gamma-Ray Bursts via the Neutrino Emission from Heated Neutron Stars

A model is proposed for gamma-ray bursts based upon a neutrino burst of ~1052 ergs lasting a few seconds above a heated collapsing neutron star. This type of thermal neutrino burst is suggested by relativistic hydrodynamic studies of the compression, heating, and collapse of close binary neutron stars as they approach their last stable orbit but may arise from other sources as well. We present a spherically symmetric hydrodynamic simulation of the formation and evolution of the pair plasma associated with such a neutrino burst. This pair plasma leads to the production of ~1051-1052 ergs in gamma rays with spectral and temporal properties consistent with many observed gamma-ray bursts.
Assessment of Air Quality During Mastoidectomy

Objectives. The Occupational Health and Safety Administration (OSHA) outlines specific requirements governing the use of respiratory protection for workers dealing with dust or other aerosolized co...
Electron-beam envelopes and matching for a combined wiggler and alternating-gradient quadrupole channel

Abstract This work studies the electron-beam envelopes and matching conditions for a combined wiggler and alternating-gradient quadrupole field for a free electron laser (FEL) that will be operated in the VUV or XUV wavelength region. The quadrupole field is assumed to vary continuously along the symmetry axis. The linearized equations of electron motion are solved analytically by using the two-scale perturbation method for a plane polarized wiggler. The electron-beam envelopes and the envelope equations, as well as the matching conditions in phase space, are obtained from the electron trajectories. A comparison with the numerical solution is presented.
On the capacity of hybrid wireless networks with opportunistic routing

This paper studies the capacity of hybrid wireless networks with opportunistic routing (OR). We first extend the opportunistic routing algorithm to exploit high-speed data transmissions in infrastructure network through base stations. We then develop linear programming models to calculate the end-to-end throughput bounds from multiple source nodes to single as well as multiple destination nodes. The developed models are applied to study several hybrid wireless network examples. Through case studies, we investigate several factors that have significant impacts on the hybrid wireless network capacity under opportunistic routing, such as node transmission range, density and distribution pattern of base stations (BTs), and number of wireless channels on wireless nodes and base stations. Our numerical results demonstrate that opportunistic routing could achieve much higher throughput on both ad hoc and hybrid networks than traditional unicast routing (UR). Moreover, opportunistic routing can efficiently utilize base stations and achieve significantly higher throughput gains in hybrid wireless networks than in pure ad hoc networks especially with multiple-channel base stations.
RFQ Development at LBL

The radio frequency quadrupole (RFQ) is a structure which can efficiently focus, bunch and accelerate low velocity ion beams. It has many features which make it particularly attractive for applications in the biomedical and nuclear sciences. There are two projects in progress at LBL where the incorporation of heavy ion RFQ technology offers substantial benefits: in the upgrade of the Bevatron local injector, and in the design of a dedicated heavy ion medical accelerator. In order to meet the requirements of these two important applications, a 200 MHz RFQ structure has been designed for ions with charge to mass ratios as low as 0.14, and a low RF power scale model has been built and tested. Construction of the high power model has begun. The status of this project is reviewed and a summary of technical specifications given.
Lorentz invariance violation and the spectrum and source power of ultrahigh energy cosmic rays

Abstract Owing to their isotropy, it is generally believed that ultrahigh energy cosmic rays (UHECRs) are extragalactic in origin. It is then expected that interactions of these cosmic rays with photons of the cosmic background radiation (CBR) should produce a drastic reduction in their flux above and energy of about 5 × 10 19 eV (50 EeV), the so-called “GZK effect”. At present, the existence of this effect is uncertain owing to conflicting observational data and small number statistics. We show here that a small amount of Lorentz invariance violation (LIV), which could turn off photomeson interactions of UHECRs with the CBR, could explain the UHECR spectrum as measured by AGASA which shows an excess of UHECRs at energies above 100 EeV. If new results from the Auger array agree with the AGASA spectrum, this may be interpreted as evidence for a small amount of LIV. If, on the other hand, the new results are consistent with the HiRes results favoring a GZK effect, this would place severe constraints on LIV and, by implication, on some Planck scale quantum gravity models. We also discuss the power requirements needed to explain the UHECR spectrum for a range of assumptions, including source evolution and LIV and show that in all cases our results disfavor a γ-ray burst origin for the UHECRs.
Dynamic contracts with partial observations: Application to indirect load control

This paper proposes a method to design an optimal dynamic contract between a principal and an agent, who has the authority to control both the principal's revenue and an engineered system. The key characteristic of our problem setting is that the principal has very limited information: the principal has no capability to monitor the agent's control or the state of the engineered system. The agent has perfect observations. With this asymmetry of information, we show that the principal can induce the agent to control both the revenue and the system processes in a way that maximizes the principal's utility, if the principal offers appropriate realtime and end-time compensation. We reformulate the dynamic contract design problem as a stochastic optimal control of both the engineered system and the agent's future expected payoff, which can be numerically solved using an associated Hamilton-Jacobi-Bellman equation. The performance and usefulness of the proposed contract are demonstrated with an indirect load control problem.
Cross-coupling of vinylpolysiloxanes with aryl iodides

Abstract Commercially available vinylpolysiloxane (1) rapidly undergoes cross-coupling reactions with aryl and alkenyl iodides in the presence of tetrabutylammonium fluoride (two to three equivalents) and Pd(dba)2 (1–5 mol%) at room temperature to afford coupling products in high yield. This process employs an inexpensive and non-toxic siloxane reagent and shows good functional group compatibility and high stereospecificity.
The Redshift of the Optical Transient Associated with GRB 010222

The gamma-ray burst (GRB) 010222 is the brightest GRB detected to date by the BeppoSAX satellite. Prompt identification of the associated optical transient (OT) allowed for spectroscopy with the Tillinghast 1.5 m telescope at F. L. Whipple Observatory while the source was still relatively bright (R 18.6 mag), within 5 hr of the burst. The OT shows a blue continuum with many superposed absorption features corresponding to metal lines at z = 1.477, 1.157, and possibly also 0.928. The redshift of GRB 010222 is therefore unambiguously placed at z ? 1.477. The high number of Mg II absorbers and especially the large equivalent widths of the Mg II, Mg I, and Fe II absorption lines in the z = 1.477 system further argue either for a very small impact parameter or that the z = 1.477 system is the GRB host galaxy itself. The spectral index of the OT is relatively steep, F? ?-0.89?0.03, and this cannot be caused by dust with a standard Galactic extinction law in the z = 1.477 absorption system. This spectroscopic identification of the redshift of GRB 010222 shows that prompt and well-coordinated follow-up of bright GRBs can be successful even with telescopes of modest aperture.
Optical backplane bus for multiprocessor-based computing systems

The design and architecture of bi-directional optical backplanes with single and multiple bus lines for high performance bus are reviewed and bus systems with one and 2-bus lines at a wavelength of 850 nm are experimentally demonstrated. For optical backplanes with single-bus line, a speed of 1.2 Gbit/sec at a wavelength of 1,3 µm is demonstrated. Arrays of multiplexed holograms are employed, in conjunction with a waveguiding plate within which cascaded fanouts are generated. For the backplane bus system containing multiple bus lines and 9 processor/memory boards, VCSELs (Vertical Cavity Surface Emitting Lasers) and photodetector arrays, such parameters as power budget, misalignment and packaging related issues are discussed. With the introduction of GRIN lenses into the backplane system, it is found that not only can the signal beam from the VCSELs get collimated, but die angular tolerance of the system is greatly enhanced. The optical backplane bus system developed here is transparent to higher level bus protocols, thus can support standard backplane buses such as Futurebus+, Multi-bus II, and VMEbus.
Pulsations of Delta Scuti stars.

The pulsation behavior of the Delta Scuti variables is characterized, reviewing recent observational and theoretical investigations. The theoretical masses, radii, and luminosities of the stars are listed in a table; three equilibrium models (deep radiative, shallow radiative, and convective) of linear radial and nonradial pulsations are described; the implementation of hydrodynamic simulations with these models is explained; and preliminary results are presented in graphs and discussed in detail. No evidence is found for the large amplitudes predicted by Stellingwerf (1979) on the basis of periodic solutions. 15 refs.
Facile ring cleavage of basic azetidines

Azetidines containing a basic ring nitrogen atom have been shown to undergo facile ring cleavage to afford 3-halo-1-amino propane derivatives upon exposure to alkyl bromides and acyl chlorides under certain conditions. The rate of ring cleavage appears to be determined largely by the rate at which quaternization of the azetidine nitrogen atom occurs. Alkylation of NH azetidines to afford N-alkyl azetidines can be carried out in synthetically useful yields if reaction times are kept short. As the free base, azetidines may undergo spontaneous oligomerization with concomitant ring cleavage.
Engineering Objects for Collaboration: Strategies of Ambiguity and Clarity at Knowledge Boundaries.

Prior research suggests that boundary objects gain meaning through group interaction. Drawing from the literature on strategic ambiguity, we explore the possibility that individuals strategically create potential boundary objects in an attempt to shape the meanings that groups develop. From ethnographic observations of automotive engineers, we identify 2 creation strategies: ambiguity (to create objects that support multiple meanings) and clarity (to create objects that permit a particular meaning). We detail design activities that engineers undertook to create objects under each strategy. We find that, when creating objects, engineers favored a strategy of ambiguity, which they believed would foster healthy long-term group interactions, over a strategy of clarity, which they tended to employ only when they expected resistance to their ideas.
Optimal collusion under cost asymmetry

Cost asymmetry is generally thought to hinder collusion because a more efficient firm has both more to gain from deviations and less to fear from retaliation than less efficient firms. Our paper reexamines this conventional wisdom and characterizes optimal collusion without any prior restriction on the class of strategies. We stress that firms can credibly agree on retaliation schemes that maximally punish even the most efficient firm. This implies that whenever collusion is sustainable under cost symmetry, some collusion is also sustainable under cost asymmetry; efficient collusion, however, remains more difficult to sustain when costs are asymmetric. Finally, we show that in the presence of side payments cost asymmetry facilitates collusion.
The Widom-Dyson constant for the gap probability in random matrix theory

In the bulk scaling limit for the Gaussian Unitary Ensemble in random matrix theory, the probability that there are no eigenvalues in the interval (0,2s) is given by P"s=det(I-K"s), where K"s is the trace-class operator with kernel K"s(x,y)=sin(x-y)@p(x-y) acting on L^2(0,2s). In the analysis of the asymptotic behavior of P"s as s->~, there is particular interest in the constant term known as the Widom-Dyson constant. We present a new derivation of this constant, which can be adapted to calculate similar critical constants in other problems arising in random matrix theory.
Broad Redshifted Line as a Signature of Outflow

We formulate and solve the diffusion problem of line photon propagation in a bulk outflow from a compact object (black hole or neutron star) using a generic assumption regarding the distribution of line photons within the outflow. Thomson scattering of the line photons within the expanding flow leads to a decrease of their energy which is of first order in v/c, where v is the outflow velocity and c is the speed of light. We demonstrate that the emergent line profile is closely related to the time distribution of photons diffusing through the flow (the light curve) and consists of a broad redshifted feature. We analyzed the line profiles for the general case of outflow density distribution. We emphasize that the redshifted lines are intrinsic properties of the powerful outflow that are supposed to be in many compact objects.
Reaction of tellurium with phenylacetylene: a reinvestigation

Abstract The reaction of powdered tellurium with phenylacetylene under strongly basic conditions yields cis and trans −2, 6- diphenyl-1, 4-ditellurafulvenes, rather than Z and E isomers of a five-membered cyclic ditelluride, as recently reported.
Multiple shock-shock interference on a cylindrical leading edge

The details of an experimental study of shock wave interference heating on a cylindrical leading edge representative of the cowl of a rectangular hypersonic engine inlet are presented. This Mach 8 study has provided the first detailed pressure and heat transfer rate distributions on a cylinder resulting from a two-dimensional shockwave interference pattern created by two incident oblique shock waves intersecting the cylinder bow shock wave. The peak heat transfer rate was 38 times the undisturbed flow stagnation point level and occurred when the two oblique shock waves coalesced prior to intersecting the cylinder bow shock wave. Development of pressure deflection diagrams identified a new interference pattern consisting of concomitant supersonic jets separated from each other by a shear layer and submerged in the subsonic region between the bow shock wave and body.
Fast Accretion of Small Planetesimals by Protoplanetary Cores

We explore the dynamics of small planetesimals coexisting with massive protoplanetary cores in a gaseous nebula. Gas drag strongly affects the motion of small bodies, leading to the decay of their eccentricities and inclinations, which are excited by the gravity of protoplanetary cores. Drag acting on larger (1 km), high-velocity planetesimals causes a mere reduction of their average random velocity. By contrast, drag qualitatively changes the dynamics of smaller (0.1–1 km), low-velocity objects: (1) small planetesimals sediment toward the midplane of the nebula, forming a vertically thin subdisk; (2) their random velocities rapidly decay between successive passages of the cores, and as a result, encounters with cores typically occur at the minimum relative velocity allowed by the shear in the disk. This leads to a drastic increase in the accretion rate of small planetesimals by the protoplanetary cores, allowing cores to grow faster than expected in the simple oligarchic picture, provided that the population of small planetesimals contains more than roughly 1% of the solid mass in the nebula. Fragmentation of larger planetesimals (1 km) in energetic collisions triggered by the gravitational scattering by cores can easily channel this amount of material into small bodies on reasonable timescales (<1 Myr in the outer solar system), providing a means for the rapid growth (within several million years at 30 AU) of rather massive protoplanetary cores. Effects of inelastic collisions between planetesimals and presence of multiple protoplanetary cores are discussed.
A multi-layer market for vehicle-to-grid energy trading in the smart grid

In this paper, we propose a novel multi-layer market for analyzing the energy exchange process between electric vehicles and the smart grid. The proposed market consists essentially of two layers: a macro layer and a micro layer. At the macro layer, we propose a double auction mechanism using which the aggregators, acting as sellers, and the smart grid elements, acting as buyers, interact so as to trade energy. We show that this double auction mechanism is strategy-proof and converges asymptotically. At the micro layer, the aggregators, which are the sellers in the macro layer, are given monetary incentives so as to sell the energy of associated plug-in hybrid electric vehicles (PHEVs) and to maximize their revenues. We analyze the interaction between the macro and micro layers and study some representative cases. Depending on the elasticity of the supply and demand, the utility functions are analyzed under different scenarios. Simulation results show that the proposed approach can significantly increase the utility of PHEVs, compared to a classical greedy approach.
Multi-layer hydrostatic equilibrium of planets and synchronous moons: theory and application to Ceres and to solar system moons

The hydrostatic equilibrium of multi-layer bodies lacks a satisfactory theoretical treatment despite its wide range of applicability. Here we show that by using the exact analytical potential of homogeneous ellipsoids we can obtain recursive analytical solutions and an exact numerical method for the hydrostatic equilibrium shape problem of multi-layer planets and synchronous moons. The recursive solutions rely on the series expansion of the potential in terms of the polar and equatorial shape eccentricities, while the numerical method uses the exact potential expression. These solutions can be used to infer the interior structure of planets and synchronous moons from their observed shape, rotation, and gravity. When applied to the dwarf planet Ceres, we show that it is most likely a differentiated body with an icy crust of equatorial thickness 30-90 km and a rocky core of density 2.4-3.1 g cm–3. For synchronous moons, we show that the J 2/C 22 10/3 and the (b – c)/(a – c) 1/4 ratios have significant corrections of order Ω2/(πGρ), with important implications for how their gravitational coefficients are determined from fly-by radio science data and for how we assess their hydrostatic equilibrium state.
STRUCTURE OF TRI-TERT-BUTYLSILANE BY ELECTRON DIFFRACTION AND MOLECULAR MECHANICS

A model force field for silanes is constructed by extending the model field MUB-2 to include silicon, for the following purposes: the calculation, via normal coordinate analyses,of amplitudes of vibration and shrinkage corrections for use in gas-phase electrondiffraction analyses, and the calculation of molecular structure by means of molecular mechanics. All of these applications are carried out in conjunction with an electrondiffraction study of [(CH,),C] ,SiH. Evidence of significant steric strain is obtained in both the diffraction and the molecular-mechanics investigations. Diffraction results include the structural parameters (*3u) r,(Si-C) = l-934(6) A, r,(C-C) = l-548( 3) A, r&C- H) = 1.121(9) A, LHSiC = 105.3(1.3)‘, (LSiCC), = 111.5(0.5)“, LCCH = 110.0(1.5)“, t-butyl torsion = 10(3)“, t-butyl tilt = 2.7(2.4)“. Experimental and calculated structures and amplitudes are in satisfactory agreement. The present compound is found to be appreciably less strained than its hydrocarbon analog [(CH,),C],CH, somewhat more strained than [(CH,),Si] ,CH, and much more strained than [(CH,),Si] ,SiH. Molecularmechanics results are presented for the present compound and its carbon and silicon analogs.
Influence of Doping Profiles on p-type AlGaN/GaN Superlattices

Transport properties of modulation-, shifted-modulation-, and uniformly doped Al 0.20 Ga 0.80 N/GaN superlattices are reported. The modulation-doped sample is doped only in the AlGaN barriers. The shifted-modulation-doped sample has its dopants shifted by one-quarter period. Measurements reveal a strong improvement in mobility and resistivity for the modulation-doped and shifted-modulation-doped structures versus the uniformly doped structure. The modulation-doped sample has a mobility of 9.2 and 36 cm 2 /Vs at 300 and 90 K, respectively, and a very low resistivity of 0.20 and 0.068 Ωcm at 300 and 90 K, respectively. Capacitance-voltage profiling shows multiple two-dimensional hole gases. The results are consistent with a reduction of neutral impurity scattering for modulation-doped structures as compared to uniformly doped structures.
Private Crop Insurers and the Reinsurance Fund Allocation Decision

This research investigates the strategic behavior of private crop insurance firms reinsured by the USDA through the Standard Reinsurance Agreement. This arrangement allows the private firm to strategically allocate individual policies into different risk-sharing arrangements. Thus, firm earnings are conditioned upon accurately forecasting policy loss experience. Our analysis begins with models investigating the characteristics explaining the placement of policies into the assigned risk fund. Then a simulation model of the SRA is used to compare the post-SRA returns of actual firm allocations to two alternative allocation strategies based on a aggregate models and a policy-level econometric
Propagating Buckle Arrestors for Offshore Pipelines

When an underwater pipeline is buckled in the presence of sufficient external pressure, a propagating buckle is initiated, and the buckle front will propagate along the pipeline until a region of much less external pressure is reached. This paper describes the results of experimental research on methods of arresting the advancement of a propagating buckle along the pipeline. The arresting capacities of three types of buckle arrestors conceived during this program, free-ring, welded-ring, and heavy-walled section arrestors, are described in detail. Results of propagating pressure experiments are also presented.
Calculation of three-dimensional low Reynolds number flows

An interactive boundary-layer stability-transition approach is used to calculate the performance characteristics of an infinite swept wing at low Reynolds numbers for several angles of attack. The in viscid flow solutions are obtained from an inviscid method based on conformal mapping and the viscous flow solutions from an inverse boundary-layer scheme which uses the Hilbert integral formulation to couple the inviscid and viscous flow. The onset of transition is calculated by the e" method, based on twoand three-dimensional versions of linear stability theory. Calculated results for an infinite swept wing with an Eppler airfoil cross section are presented for sweep angles corresponding to A = 30, 40, and 45 deg, and for Reynolds numbers of 3 x 10 and 4.6 x 10. The effect of sweep angle on lift and drag coefficients is investigated together with the accuracy of predicting the onset of transition with two versions of the e" method.
Partial cubes: structures, characterizations, and constructions

Partial cubes are isometric subgraphs of hypercubes. Structures on a graph defined by means of semicubes, and Djokovic's and Winkler's relations play an important role in the theory of partial cubes. These structures are employed in the paper to characterize bipartite graphs and partial cubes of arbitrary dimension. New characterizations are established and new proofs of some known results are given. The operations of Cartesian product and pasting, and expansion and contraction processes are utilized in the paper to construct new partial cubes from old ones. In particular, the isometric and lattice dimensions of finite partial cubes obtained by means of these operations are calculated.
Surgical Stage IV Endometrial Carcinoma: A Study of 47 Cases

Between 1976 and 1991, 47 patients with surgical Stage IV endometrial carcinoma were treated. Patients were identified from the tumor registry and charts were retrospectively reviewed. Surgical curves using the Kaplan-Meier product-limit method and Cox regression analysis were used to identify independent prognostic factors. Overall, median survival was only 12 months. Using univariate analysis there was no statistically significant difference in survival between age (P = 0.41), histology (P = 0.54), grade (P = 0.91), disease site (P = 0.32), or clinical stage (P = 0.87). In patients whose disease was surgically cytoreduced, the median survival was 18 months compared to 8 months in those who did not undergo surgery (P = 0.0001). Evaluation of other treatment modalities by univariate analysis revealed improved survival in those patients who received cyclophosphamide, doxorubicin, and cisplatin (P = 0.0007), decreased survival in those who received radiation therapy compared to surgery (P = 0.023), and no statistically significant difference in survival with progestins. By multivariate analysis successful cytoreduction was the only statistically significant prognostic variable (P = 0.04). This 15-year retrospective review confirms that prognosis for women with Stage IV endometrial cancer is extremely poor. However, if hysterectomy with cytoreduction is feasible, surgery should be performed because survival may be improved.
Planetary impact probabilities for long-period comets

Abstract Planetary impact probabilities for long-period (near-parabolic) comets are determined by averaging Opik's equations over inclination and perihelion distance for each planet. These averaged values compare well with the results of more elaborate Monte Carlo calculations. The impact probabilities are proportional to the square of the normalized capture radius of each planet, which in turn is a function of the planet's radius and mass, so that the major planets have the highest impact probabilities. Encounter velocities have an average value of 3 1 2 times the planetary orbital velocity but the most probable encounter velocities are slightly higher than this for the terrestrial planets and slightly lower for the major planets. Comparison of the impact probabilities with the cratering record, corrected for gravity and velocity effects, indicates that long-period comets may account for 3 to 9% of the observed large crattes (diameter > 10 km) on the terrestrial planets. The inclination and perihelion properties of the impact probabilities obtained from numerical averaging provide a simple method for determining the impact probabilities for nonuniform distributions. The perihelion distribution of long period comets from J. A. Fernandez ((1981) Astron. Astrophys.96, 26–35) results in a crater production rate quite similar throughout the solar system, unlike that of a uniform perihelion distribution.
Constraints on the equation of state of neutron star matter from observations of kilohertz QPOs

Abstract The frequencies of the highest-frequency kilohertz QPOs recently discovered in some sixteen neutron stars in low-mass X-ray binary systems are most likely the orbital frequencies of gas in Keplerian orbit around these neutron stars. If so, these QPOs provide tight upper bounds on the masses and radii of these neutron stars and important new constraints on the equation of state of neutron star matter. If the frequency of a kilohertz QPO can be established as the orbital frequency of gas at the innermost stable circular orbit, this would confirm one of the key predictions of general relativity in the strong-gravity regime. If the spin frequency of the neutron star can also be determined, the frequency of the QPO would fix the mass of the neutron star for each assumed equation of state. Here we show how to derive mass and radius bounds, using the kilohertz QPOs, for nonrotating and slowly rotating stars, and discuss how these bounds are affected by rapid stellar rotation and radial radiation forces. We also describe observational results that would be strong evidence for the presence of an innermost stable circular orbit. No such strong evidence is present in current data, but future prospects are excellent.
IMPULSIVE PHASE CORONAL HARD X-RAY SOURCES IN AN X3.9 CLASS SOLAR FLARE

We present the analysis of a pair of unusually energetic coronal hard X-ray (HXR) sources detected by the Reuven Ramaty High Energy Solar Spectroscopic Imager during the impulsive phase of an X3.9 class solar flare on 2003 November 3, which simultaneously shows two intense footpoint (FP) sources. A distinct loop top (LT) coronal source is detected up to {approx}150 keV and a second (upper) coronal source up to {approx}80 keV. These photon energies, which were not fully investigated in earlier analysis of this flare, are much higher than commonly observed in coronal sources and pose grave modeling challenges. The LT source in general appears higher in altitude with increasing energy and exhibits a more limited motion compared to the expansion of the thermal loop. The high-energy LT source shows an impulsive time profile and its nonthermal power-law spectrum exhibits soft-hard-soft evolution during the impulsive phase, similar to the FP sources. The upper coronal source exhibits an opposite spatial gradient and a similar spectral slope compared to the LT source. These properties are consistent with the model of stochastic acceleration of electrons by plasma waves or turbulence. However, the LT and FP spectral index difference (varying from {approx}0 to 1) ismore » much smaller than commonly measured and than that expected from a simple stochastic acceleration model. Additional confinement or trapping mechanisms of high-energy electrons in the corona are required. Comprehensive modeling including both kinetic effects and the macroscopic flare structure may shed light on this behavior. These results highlight the importance of imaging spectroscopic observations of the LT and FP sources up to high energies in understanding electron acceleration in solar flares. Finally, we show that the electrons producing the upper coronal HXR source may very likely be responsible for the type III radio bursts at the decimetric/metric wavelength observed during the impulsive phase of this flare.« less
Effectiveness of copula-extreme value theory in estimating value-at-risk: empirical evidence from Asian emerging markets

A traditional Monte Carlo simulation using linear correlations induces estimation bias in measuring portfolio value-at-risk (VaR), due to the well-documented existence of fat-tail, skewness, truncations, and non-linear relations in return distributions. In this paper, we consider the above issues in modeling VaR and evaluate the effectiveness of using copula-extreme-value-based semiparametric approaches. To assess portfolio risk in six Asian markets, we incorporate a combination of extreme value theory (EVT) and various copulas to build joint distributions of returns. A backtesting analysis using a Monte Carlo VaR simulation suggests that the Clayton copula-EVT evinces the best performance regardless of the shapes of the return distributions, and that in general the copulas with the EVT provide better estimations of VaRs than the copulas with conventionally employed empirical distributions. These findings still hold in conditional-coverage-based backtesting. These findings indicate the economic significance of incorporating the down-side shock in risk management.
Universal thermopower of bad metals

``Bad metals'' are known to have a large linear resistivity at high $T$ that is universally seen near the Mott-Hubbard insulating phase. Less well known is that the thermopower $\ensuremath{\alpha}(T)$ of the Mott-Hubbard systems also exhibits simple universal features: (i) close to the insulating phase, where the resistivity has a low-temperature upturn, $\ensuremath{\alpha}(T)$ has a pronounced low-$T$ peak that shifts to higher $T$ with doping; (ii) when the resistivity is nearly linear, which occurs at moderate doping, $\ensuremath{\alpha}(T)$ has a small low-$T$ peak that shifts to lower $T$ with doping and has a high-$T$ sign change; and (iii) at the highest doping, where the resistivity acquires a ${T}^{2}$ term, $\ensuremath{\alpha}(T)$ is negative and depends monotonically on $T$. The universality $\ensuremath{\alpha}(T)$ can be understood using the Kelvin formula and the fact that the chemical potential for doped Mott insulators displays similar behavior at high $T$. The universality is illustrated with the exact solution of the simplest model for a doped Mott insulator at high $T$.
Small Area Estimation via Multivariate Fay–Herriot Models with Latent Spatial Dependence

Summary The Fay–Herriot model is a standard model for direct survey estimators in which the true quantity of interest, the superpopulation mean, is latent and its estimation is improved through the use of auxiliary covariates. In the context of small area estimation, these estimates can be further improved by borrowing strength across spatial regions or by considering multiple outcomes simultaneously. We provide here two formulations to perform small area estimation with Fay–Herriot models that include both multivariate outcomes and latent spatial dependence. We consider two model formulations. In one of these formulations the outcome-by-space dependence structure is separable. The other accounts for the cross dependence through the use of a generalized multivariate conditional autoregressive (GMCAR) structure. The GMCAR model is shown, in a state-level example, to produce smaller mean square prediction errors, relative to equivalent census variables, than the separable model and the state-of-the-art multivariate model with unstructured dependence between outcomes and no spatial dependence. In addition, both the GMCAR and the separable models give smaller mean squared prediction error than the state-of-the-art model when conducting small area estimation on county level data from the American Community Survey.