cssi/SciSciGPT-SciSciNet huggingface dataset:
Valid inequalities based on simple mixed-integer sets

In this paper we use facets of simple mixed-integer sets with three variables to derive a parametric family of valid inequalities for general mixed-integer sets. We call these inequalities two-step MIR inequalities as they can be derived by applying the simple mixed-integer rounding (MIR) principle of Wolsey (1998) twice. The two-step MIR inequalities define facets of the master cyclic group polyhedron of Gomory (1969). In addition, they dominate the strong fractional cuts of Letchford and Lodi (2002).
Thermal radiation in 1D photonic crystals

Abstract Optical properties of periodic structures, or photonic crystals, have been studied extensively over the last two decades. While thermal radiation from surface grating structures has also been investigated, radiation inside a photonic crystal has not been investigated completely. We have developed a method to analyze thermal radiation in 1D periodic layered media using a modified dyadic Green's function method and the fluctuation–dissipation theorem. Using the method, thermal radiation between layers in periodic structures made of ultra-thin metallic films is analyzed. The unusual features of thermal radiation in such structures are explained.
A model for effective field enhancement for Fowler-Nordheim field emission

The local field enhancement factor β is often introduced in the Fowler–Nordheim equation to represent the geometrical effects at the surface of the cathode, where β(s)=En(s)∕E0 for macroscopic applied field E0. Local variation of β determines the local normal surface electric field, En(s), resulting in local dependence of injection current by the Fowler–Nordheim law. In computational models, it is impractical to determine the time-dependent local surface field each time step on a microscopic space scale. Effective β is introduced in this paper which allows us to study the emission properties at a macroscopic scale. Microscopic (subgrid) local effective β is calculated only at the initial time step, and then the effective β can be recomputed for different surface electrical field through this model. The model allows reduction of dimensionality as well as the ability to include subgrid effects. The model is demonstrated on fundamental cases and compared to a calculation with a mesh fine enough to resolve th...
Biosynthesis of cylindrospermopsin.

Studies on the biosynthesis of cylindrospermopsin (1), a potent hepatotoxin associated with the cyanobacterium Cylindrospermopsis raciborskii, indicate that 1 is an acetogenin with guanidinoacetic acid serving as the starter unit of the polyketide chain. Feeding experiments show that C14 and C15 of 1 are derived from C1 and C2 of glycine, respectively, and C4 through C13 arise from five contiguous acetate units attached head to tail. The methyl carbon on C13 originates from the C1 pool. The starter unit, established by the incorporation of [guanidino-13C,α-15N]-guanidinoacetic acid into N16 and C17 of 1, does not appear to be formed from glycine by known amidination pathways. The origin of the NH−CO−NH segment in the uracil ring is also unknown.
CJ-12,371 and CJ-12,372, two novel DNA gyrase inhibitors. Fermentation,isolation, structural elucidation and biological activities.

A fermentation broth of an unidentified fungus (N983-46) was found to produce DNA gyrase inhibitors, CJ-12, 371 (1) and CJ-12, 372 (2). Following isolation by solvent extraction and silica gel and ODS (reverse phase) chromatographies, the structures were determined to be novel spiro-ketal compounds with S-configuration at position C-1. CJ-12, 371 and CJ-12, 372 inhibit both DNA supercoiling and relaxation mediated by Escherichia coli DNA gyrase. The interaction of these compounds with DNA gyrase appears to be novel in that the compounds inhibit supercoiling and relaxation without blocking religation; thus, no cleavage intermediate of double strand DNA is observed. Both compounds have antibacterial activity against several species of pathogenic Grampositive bacteria, with MICs between 25 and 100μg/ml. These results suggest that the antibacterial potency of CJ-12, 371 and CJ-12, 372 is attributed to the inhibition of DNA gyrase. However, the compounds did not inhibit DNA gyrase selectively, as they also inhibited eukaryotic topoisomerase II-mediated relaxation. Semi-synthetic modifications to the dihydroxy motif in CJ-12, 371 altered both gyrase- and topoisomerase Il-inhibitory activities, but did not enhance selectivity.
Crystal structure of glycoprotein C from Rift Valley fever virus

Rift Valley fever virus (RVFV), like many other Bunyaviridae family members, is an emerging human and animal pathogen. Bunyaviruses have an outer lipid envelope bearing two glycoproteins, GN and GC, required for cell entry. Bunyaviruses deliver their genome into the host-cell cytoplasm by fusing their envelope with an endosomal membrane. The molecular mechanism of this key entry step is unknown. The crystal structure of RVFV GC reveals a class II fusion protein architecture found previously in flaviviruses and alphaviruses. The structure identifies GC as the effector of membrane fusion and provides a direct view of the membrane anchor that initiates fusion. A structure of nonglycosylated GC reveals an extended conformation that may represent a fusion intermediate. Unanticipated similarities between GC and flavivirus envelope proteins reveal an evolutionary link between the two virus families and provide insights into the organization of GC in the outer shell of RVFV.
LONG-TERM VARIABILITY IN THE OPTICAL SPECTRUM OF THE SEYFERT GALAXY NGC 2992

New spectra of NGC 2992 from the Cerro Tololo Inter-American Observatory show that this nearby active galactic nucleus changed its type classification to a Seyfert 2 in 2006. It was originally classified as a Seyfert 1.9, and has been previously seen as a Seyfert 1.5 with strong broad Hα emission. A comparison of the reddening and equivalent hydrogen column density derived for the narrow-line region from these new data with those previously calculated for different regions closer to the nucleus shows them to be very similar, and suggests that these different regions are all being absorbed by the same opacity source, a large 100 pc scale dust lane running across the nucleus. However, obscuration by dust in this lane is probably not responsible for classification changes which occur in only a few years. It is more likely that NGC 2992's observed variations are due to a highly variable ionizing continuum. We therefore conclude that, although NGC 2992 was originally identified as a Seyfert 1.9, this was not because of an oblique viewing angle through the atmosphere of a central dusty torus, but because its active nucleus was identified when it was in a low-continuum state.
Thermal Fracture of Multilayer Ceramic Thermal Barrier Coatings

Controlled experiments and a corresponding analytical model were developed to investigate the reasons for crack initiation in multilayer ceramic thermal barrier coatings. The experiments and model determined that surface cracks form as a result of tensile stresses created following stress relaxation in the ceramic at steady-state high temperatures (about 900°C–1100°C). Interface cracks generated by out-of-plane stresses are affected by the presence of these surface cracks and thermal transients and, possibly, edge effects.
Adaptive Optics Imaging and Spectroscopy of Cygnus A. I. Evidence for a Minor Merger

We present Keck II adaptive optics near-infrared imaging and spectroscopic observations of the central regions of the powerful radio galaxy Cyg A. The 005 resolution images clearly show an unresolved nucleus between two spectacular ionization/scattering cones. We report the discovery of a relatively bright (K' ~ 19) secondary point source 04 or 400 pc in projection southwest of the radio nucleus. The object is also visible in archival Hubble Space Telescope optical images, although it is easily confused with the underlying structure of the host. Although the near-infrared colors of this secondary point source are roughly consistent with those of an L dwarf, its spectrum and optical-to-infrared spectral energy distribution (SED) virtually rule out the possibility that it may be any foreground projected object. We conclude that the secondary point source is likely to be an extragalactic object associated with Cyg A. We consider several interpretations of the nature of this object, including: a young star cluster peering through the dust at the edge of one of the ionization cones; an older, large globular cluster; a compact cloud of dust or electrons that is acting as a mirror of the hidden active nucleus; and the dense core of a gas-stripped satellite galaxy that is merging with the giant elliptical host. The data presented here are most consistent with the minor merger scenario. The spectra and SED of the object suggest that it may be a densely packed conglomeration of older stars heavily extincted by dust, and its high luminosity and compact nature are consistent with those of a satellite that has been stripped to its tidal radius. Further spectroscopic observations are nevertheless necessary to confirm this possibility.
Sampling-based algorithms for optimal motion planning

During the last decade, sampling-based path planning algorithms, such as probabilistic roadmaps (PRM) and rapidly exploring random trees (RRT), have been shown to work well in practice and possess theoretical guarantees such as probabilistic completeness. However, little effort has been devoted to the formal analysis of the quality of the solution returned by such algorithms, e.g. as a function of the number of samples. The purpose of this paper is to fill this gap, by rigorously analyzing the asymptotic behavior of the cost of the solution returned by stochastic sampling-based algorithms as the number of samples increases. A number of negative results are provided, characterizing existing algorithms, e.g. showing that, under mild technical conditions, the cost of the solution returned by broadly used sampling-based algorithms converges almost surely to a non-optimal value. The main contribution of the paper is the introduction of new algorithms, namely, PRM* and RRT*, which are provably asymptotically optimal, i.e. such that the cost of the returned solution converges almost surely to the optimum. Moreover, it is shown that the computational complexity of the new algorithms is within a constant factor of that of their probabilistically complete (but not asymptotically optimal) counterparts. The analysis in this paper hinges on novel connections between stochastic sampling-based path planning algorithms and the theory of random geometric graphs.
A combined voltammetry and electrochemical quartz crystal microgravimetry study of the reduction of aqueous Se(IV) at gold

Abstract The reduction of Se(IV) in 0.5 M Na 2 SO 4 is complex and does not proceed via the Se(IV) → Se(0) → Se(II-) scheme considered by most previous authors. A combined use of voltammetry and electrochemical quartz crystal microgravimetry techniques shows that the direct 6e − Se(IV) → Se(II-) reduction pathway competes with the initial four-electron process. Coupling with a subsequent (fast) chemical reaction between Se(II-) and Se(IV) results in the further deposition of Se(0) at the electrode surface. The electrochemical behavior at more negative potentials reflects a complex interplay of the four-electron and six-electron reduction processes and the chemical reaction along with the effect of Se(II-) ions stripped from the initial selenium layer. Thus the delicate balance between these is influenced by two variables, namely the potential and the Se(II-) concentration in the electrolyte. Further data in support of our mechanistic scheme are furnished by measurements with a Au disk electrode oriented “face-down” in the cell as well as by hydrodynamic voltammetry experiments.
A time-reversal invariant topological phase at the surface of a 3D topological insulator

A 3D fermionic topological insulator has a gapless Dirac surface state protected by time-reversal symmetry and charge conservation symmetry. The surface state can be gapped by introducing ferromagnetism to break time-reversal symmetry, introducing superconductivity to break charge conservation, or entering a topological phase. In this paper, we construct a minimal gapped topological phase that preserves both time-reversal and charge conservation symmetries and supports Ising-type non-Abelian anyons. This phase can be understood heuristically as emerging from a surface s-wave superconducting state via the condensation of eight-vortex composites. The topological phase inherits vortices supporting Majorana zero modes from the surface superconducting state. However, since it is time-reversal invariant, the surface topological phase is a distinct phase from the Ising topological phase, which can be viewed as a quantum-disordered spin-polarized px + ipy superconductor. We discuss the anyon model of this topological phase and the manner in which time-reversal symmetry is realized in it. We also study the interfaces between the topological state and other surface gapped phases.
LINKING SHORT GAMMA-RAY BURSTS AND THEIR HOST GALAXIES

The luminosities of short-duration gamma-ray burst (SGRB) host galaxies appear to be anticorrelated with both the isotropic equivalent gamma-ray energy and the gamma-ray luminosity of the explosions, based on a sample of 12 bursts with host galaxy redshifts and photometry. The correlation does depend on the correct identification of the GRB 050509b host, but is otherwise robust. In particular, simple observational selection effects only strengthen the statistical significance of this correlation, from ~95% to ~99%. The correlation may indicate that there are two physically distinct groups of SGRBs. If so, it requires that the more luminous class of explosions be associated with the younger class of progenitors. Alternatively, it could be due to a continuous distribution of burst and host properties, in which case it could be used as a crude SGRB distance indicator. As one possible explanation, we find that the effect of binary neutron star masses on inspiral time and energy reservoir produces a correlation of the appropriate sign, but does not automatically reproduce the correlation slope or the full range of SGRB energy scales. If confirmed by larger samples, this correlation will provide a valuable new constraint on SGRB progenitor models.
Thrust Measurements of the Ferroelectric Plasma Thruster

This paper details the calculation and measurement of average thrust in the ferroelectric plasma thruster. The effect of applied voltage on thrust is evaluated. In addition, the construction and calibration of a pulsed thrust stand is presented. Characteristics of the thruster include an average power of 6 W, thrust of 68-87 muN, calculated specific impulse of 1450 s, and a thruster mass of 5.7 g. Additional benefits of the thruster include impulse bits less than 1 nN ldr s, only one power supply needed for operation, and the ability to emit both electrons and ions.
Probing the QCD critical point with relativistic heavy-ion collisions

We utilize an event-by-event relativistic hydrodynamic calculation performed at a number of different incident beam energies to investigate the creation of hot and dense QCD matter near the critical point. Using state-of-the-art analysis and visualization tools we demonstrate that each collision event probes QCD matter characterized by a wide range of temperatures and baryo-chemical potentials, making a dynamical response of the system to the vicinity of the critical point very difficult to isolate above the background.
Endurance exercise training in Guillain-Barre Syndrome

The purpose of this case study was to determine whether an individual who had residual deficits following an acute incidence of Guillain-Barre Syndrome (GBS) would experience improved physiological adaptations following aerobic endurance training. A 57-year-old man who needed the aid of a crutch for walking three years following an acute bout of GBS participated in this study. Peak work level (watts), oxygen consumption (VO2 mL/min; mL/kg.min), and ventilation (VE, L/min) were determined on a bicycle ergometer (BE), a Schwinn Air-Dyne ergometer (SAE), and an arm crank ergometer (ACE) before and after exercise training. Isokinetic leg strength measured using a dynamometer and total work capacity in watts using BE were also determined before and after training. The subject trained for 16 weeks at an approximate frequency of 3 days/week, an average duration of 30 minutes, and an average intensity of 75% to 80% of pretraining peak HR. A 9% and 11% improvement was seen in peak oxygen consumption for the SAE and BE, respectively. For peak ventilation, a 23% and 11% improvement was seen for the SAE and BE, respectively. For the ACE, a 16% increase in peak ventilation was seen, with no improvement in aerobic capacity. Total work capacity on the BE was improved by 29% following training. Positive improvements were also seen in isokinetic leg strength. This study demonstrated that a man still suffering residual symptoms following an incidence of GBS was able to improve his cardiopulmonary and work capacity and isokinetic strength of his legs following a supervised training program using the SAE. The subject also reported improvements in activities of daily living.
How to write a book

This article gives practical advice on technical book writing based on the author's experience. Early collection and through analysis of resource and bibliographic materials often yield extra useful information. Making the first sentences or paragraphs or pages of each unit comprehensible even to one's “grandmother” is a good first step toward making the entire text comprehensible to its intended audience. Publishing survey or review articles, speaking at conferences, and developing annotated bibliographies are ways of rehearsing chapter writing and having something to show at each stage of the work.
Gravitational effects in supersymmetric domain wall backgrounds

Abstract A recent study of supersymmetric domain walls in N=1 supergravity theories revealed a new class of domain walls interpolating between supersymmetric vacua with different non-positive cosmological constants. We classify three classes of domain wall configurations and study the geodesic structure of the induced space-time. Motion of massive test particles in such space-time shows that these walls are always repulsive from the anti-de Sitter (AdS) side, while on the Minkowski side test particles feel no force. Freely falling particles far away from a wall in an AdS vacuum have a hyperbolic world line which is the same as a Rindler particle in a Minkowski background. In addition, a new coordinate system for discussing AdS space-time is presented which eliminates the use of a periodic time-like coordinate.
A complexity-regularized quantization approach to nonlinear dimensionality reduction

We consider the problem of nonlinear dimensionality reduction: given a training set of high-dimensional data whose "intrinsic" low dimension is assumed known, find a feature extraction map to low-dimensional space, a reconstruction map back to high-dimensional space, and a geometric description of the dimension-reduced data as a smooth manifold. We introduce a complexity-regularized quantization approach for fitting a Gaussian mixture model to the training set via a Lloyd algorithm. Complexity regularization controls the trade-off between adaptation to the local shape of the underlying manifold and global geometric consistency. The resulting mixture model is used to design the feature extraction and reconstruction maps and to define a Riemannian metric on the low-dimensional data. We also sketch a proof of consistency of our scheme for the purposes of estimating the unknown underlying pdf of high-dimensional data
Does the Slovenian Public Work Program Increase Participants' Chances to Find a Job?

Abstract Vodopivec, Milan—Does the Slovenian Public Work Program Increase Participants' Chances to Find a Job? This paper analyzes the effects of the Slovenian public works program on the employability of the participants from 1992 to 1996. Immediately upon the completion, the program helps the participants find a job but, in the longer run, the positive effect is dissipated and the impact becomes negative. Some of the exits to employment can be attributed to converting public jobs positions into permanent ones and the longer term negative impact on finding a job could be related to stigmatization of the participants. The study shows also that public works reduce the exit rate to inactivity.J. Comp. Econom.,March 1999, 27(1), pp. 113–130. The World Bank, Washington, DC 20433, and GEA College of Entrepeneurship, 6320 Portoroz, Slovenia.
The Rate and Spatial Distribution of Novae in M101 (NGC 5457)

A new multiepoch Hα imaging study of M101 (NGC 5457) has been carried out as part of a larger campaign to study the rate and stellar population of extragalactic novae. The survey yielded a total of 13 nova detections from 10 epochs of M101 observations spanning a 3 yr period. After correcting for the temporal coverage and survey completeness, a global nova rate of 11.7+ 1.9−1.5 yr−1 is found. This value corresponds to a luminosity-specific nova rate of 1.23 ± 0.27 novae per year per 1010 L☉ ,K when the K luminosity is derived from the B − K color, or 1.94 ± 0.42 novae per year per 1010 L☉ ,K when the K magnitude from the Two Micron All Sky Survey is used. These values are consistent with previous estimates by Shafter et al. that were based on more limited data. The spatial distribution of the combined nova sample from the present survey and from the earlier Shafter et al. survey shows that the specific frequency of novae closely follows the integrated background light of the galaxy.
Stereochemical Elucidation of New Sagittamides C–F from a Didemnid Ascidian

Four new minor congeners, sagittamides C–F, were isolated from an unidentified Didemnid tunicate that previously afforded sagittamides A and B. The structures were determined by interpretation of spectroscopic data, degradation to amino acids, and comparisons with sagittamide A. An unexpected change in relative configuration of the hexacetoxy C5–C10 stereoelement is present in sagittamides D and F. A tentative assignment of configuration was possible through a systematic deduction based on analysis of 13C NMR data and symmetry considerations.
A Markov model acoustic phonetic component for automatic speech recognition

A Markov-model acoustic-phonetic component is constructed for the synthesis of standard acoustic representations of connected speech. The primary building blocks are phones with Markov models structured so that phone length, spectral power and fundamental frequency are parametrically controlled. The model generates acoustic parameter outputs at 10-ms time steps. The acoustic-phonetic component permits matching between actual acoustic data and internally modeled acoustic data, and can be employed in various ways—to label speech automatically. as a phone decorder to obtain estimated phone strings, and in speech recognizers which match at the acoustic level.
External effects in U.S. procyclical productivity

Abstract In this paper we highlight a new dimension of the aggregate procyclical productivity phenomenon. We show that estimates of the degree of returns to scale are larger for manufacturing as a whole than for two-digit industries. Since this difference must be due to factors that are only internalized at the most aggregate level, we term it an external effect. This result rules out explanations based on own-input variation —such as true increasing returns and unmeasured factor utilization tied to own-activity —as the sole explanations for aggregate procyclical productivity. We explore several potential explanations of this external effect.
Graphs of subgroups of free groups

We construct an efficient model for graphs of finitely generated subgroups of free groups. Using this we give a very short proof of Dicks’s reformulation of the strengthened Hanna Neumann Conjecture as the Amalgamated Graph Conjecture. In addition, we answer a question of Culler and Shalen on ranks of intersections in free groups. The latter has also been done independently by R P Kent IV.
Extreme Doppler precision with octagonal fiber scramblers

The detection of Earth analogs with radial velocity requires long-term precision of 10 cm/s. One of the factors limiting precision is variation in instrumental profile from observation to observation due to changes in the illumination of the slit and spectrograph optics. Fiber optics are naturally efficient scramblers. Our research is focused on understanding the scrambling properties of fibers with different geometries. We have characterized circular and octagonal fibers in terms of focal ratio degradation, near-field and far-field distributions. We have characterized these fibers using a bench-mounted high-resolution spectrograph: the Yale Doppler Diagnostics Facility (YDDF).
Chiral synthesis of L-γ-carboxyglutamic acid (L-Gla)

A two step synthesis involving the use of a chiral template, benzyl (2R, 3S)-(−)-6-oxo-2,3-diphenyl-4-morpholine-carboxylate3 (5a), provides orthogonally protected L-Gla (9) in 60% overall yield (>99% ee), with no resolution required.
Cancer Dissemination: A Consequence of limited Carrying Capacity?

Assuming that there is feedback between an expanding cancer system and its organ-typical microenvironment, we argue here that such local tumor growth is initially guided by co-existence rather than competition with the surrounding tissue. We then present a novel concept that understands cancer dissemination as a biological mechanism to evade the specific carrying capacity limit of its host organ. This conceptual framework allows us to relate the tumor system's volumetric growth rate to the host organ's functionality-conveying composite infrastructure, and, intriguingly, already provides useful insights into several clinical findings.
Quantum hair, instantons, and black hole thermodynamics: some new results

Abstract We present results obtained by a consideration of the non-classical energy-momentum tensor associated with Euclidean instantons outside the event horizon of black holes. We demonstrate here how this allows for an analytic estimate to be made of the effect of discrete quantum hair on the temperature of the black hole, in which the role of violations of the weak energy condition associated with instantons is made explicit, and in which the previous results of Coleman, Preskill, and Wilczek are extended. Last, we demonstrate how the existence of a non-classical electric field outside the event horizon of black holes, uncovered by these authors, can be identified with a well-known effect in the Abelian Higgs mode] in two dimensions. In this case, there is a one-to-one connection between the discrete charge of a black hole and a topological phase in two dimensions.
On the Hopf conjecture with symmetry

The Hopf conjecture states that an even-dimensional manifold with positive curvature has positive Euler characteristic. We show that this is true under the assumption that a torus of sufficiently large dimension acts by isometries. This improves previous results by replacing linear bounds by a logarithmic bound. The new method that is introduced is the use of Steenrod squares combined with geometric arguments of a similar type to what was done before.
Parallel multiple search

Abstract Two sequences of items sorted in increasing order are given: a sequence A of size n and a sequence B of size m. It is required to determine, for every item of A, the smallest item of B (if one exists) that is larger than it. In this paper, we present two algorithms for the problem. The first algorithm requires O(log m + log n) time using n processors on an EREW PRAM. On an EREW PRAM with p(p≤min{m,n}) processors, the second algorithm runs in O(log n + n p time when m≤n,or in O(log m + ( n p )log(2 m n )) time when m>n. The second algorithm is optimal.
Controlling magnetism with multiferroics

Multiferroics, materials combining multiple order parameters, offer an exciting way of coupling phenomena such as electronic and magnetic order. Using epitaxial growth and heteroepitaxy, researchers have grown high-quality thin films and heterostructures of the multiferroic BiFeO 3 . The ferroelectric and antiferromagnetic domain structure and coupling between these two order parameters in BiFeO 3 is now being studied. We describe the evolution of our understanding of the connection between structure, properties, and new functionalities (including electrical control of magnetism) using BiFeO 3 as a model system.
A general and efficient copper catalyst for the amidation of aryl halides.

An experimentally simple and inexpensive catalyst system was developed for the amidation of aryl halides by using 0.2−10 mol % of CuI, 5−20 mol % of a 1,2-diamine ligand, and K3PO4, K2CO3, or Cs2CO3 as base. Catalyst systems based on N,N‘-dimethylethylenediamine or trans-N,N‘-dimethyl-1,2-cyclohexanediamine were found to be the most active even though several other 1,2-diamine ligands could be used in the easiest cases. Aryl iodides, bromides, and in some cases even aryl chlorides can be efficiently amidated. A variety of functional groups are tolerated in the reaction, including many that are not compatible with Pd-catalyzed amidation or amination methodology.
A three-dimensional network structure built from selenodiphosphate(IV) and copper selenide tetrahedral building blocks: K3Cu3P3Se9†

The reaction of red phosphorus, potassium polyselenide, and copper metal at moderate temperatures yields K3Cu3P3Se9. The structure was determined by single crystal X-ray diffraction (P21/c, a = 8.741(2) A, b = 10.774(2) A, c = 20.033(3) A, β = 92.96(2)°). The structure consists of [P2Se6]4−-anions that link [CuSe4] tetrahedra in an open, three-dimensional, framework structure. A Valence Electron Concentration treatment of this structure reveals six different primary tetrahedral building blocks. Eine dreidimensionale Netzwerk-Struktur mit Selenodiphosphat(IV)- und Kupferselenid-Tetraeder-Bausteinen: K3Cu3P3Se9 Die Reaktion von rotem Phosphor und Kalium-Polyselenid mit Kupfer bei masigen Temperaturen fuhrt zu K3Cu3P3Se9. Die Struktur wurde durch Einkristall-Rontgenstrukturanalyse bestimmt (P21/c, a = 8.741(2) A, b = 10.774(2) A, c = 20.033(3) A, β = 92.96(2)°). Sie besteht aus [P2Se6]4−-Anionen, die die [CuSe4]-Tetraeder zu einer offenen, drei-dimensionalen Netzwerk-Struktur verbinden. Eine „Valence Electron Concentration”-Behandlung dieser Struktur zeigt sechs verschiedene „Haupttetraederbausteine”.
The impacts of index options on the underlying stocks: The case of the S&P 100

Abstract Existing theories predict lower trading volume, but ambiguous changes in price, bid–ask spread, and volatility for the underlying stocks following the advent of index derivatives. We further test these predictions around the introduction of the S&P 100 options in March 1983. Controlling for known factors respectively, we find that the listing of the S&P 100 options results in lower volume, spread, and volatility, but no price change for the underlying stocks, contrasting with the existing U.S. evidence and supporting the notion that the arrival of index derivatives induces informed and speculative portfolio traders to migrate from the underlying market to the derivatives market.
Using cellular graph embeddings in solving all pairs shortest paths problems

Abstract An algorithm for generating a succinct encoding of all pairs shortest path information in an n-vertex directed graph G with O(n) edges is presented. The edges have real-valued costs, but the graph contains no negative cycles. The algorithm runs in O(γ(G)n + (γ(G))2 log γ(G)) time, where γ(G) is a topological embedding measure that we define for the corresponding undirected graph G. The algorithm uses a decomposition of the graph into O(γ(G)) outerplanar subgraphs satisfying certain separator properties, and a linear-time algorithm for finding this decomposition is presented. An alternative encoding of all pairs shortest path information, as well as a succinct encoding of shortest distance information, is also given.
Knot Invariants and Topological Strings

We find further evidence for the conjecture relating large N Chern-Simons theory on S^3 with topological string on the resolved conifold geometry by showing that the Wilson loop observable of a simple knot on S^3 (for any representation) agrees to all orders in N with the corresponding quantity on the topological string side. For a general knot, we find a reformulation of the knot invariant in terms of new integral invariants, which capture the spectrum (and spin) of M2 branes ending on M5 branes embedded in the resolved conifold geometry. We also find an intriguing link between knot invariants and superpotential terms generated by worldsheet instantons in N=1 supersymmetric theories in 4 dimensions.
Integrated Microwave Modules - A Prospectus

Applications of monolithic and hybrid semiconductor circuit technologies to microwaves are discussed from a semitechnical and economic viewpoint. Technical feasibility of performing nearly all functions through millimeter waves is foreseen. Economic success, however, is less tangible and depends mainly on two factors: the willingness of systems people to trade increased initial cost for greatly decreased maintenance cost and the magnitude of the requirements for electronically steered antennas. The author's estimates of the business potential are discussed.
Relationship between early patterns of cerebral extraction of oxygen and outcome from severe acute traumatic brain swelling: cerebral ischemia or cerebral viability?

Objective : To evaluate outcome from severe acute traumatic diffuse brain swelling, in relation to early patterns of global cerebral extraction of oxygen. Design : Prospective, interventional study. Setting : Neuroscience intensive care unit of a university hospital. Patients : Adults (n = 205) with acute, essentially isolated brain trauma (predominantly diffuse brain swelling), undergoing routine early monitoring of cerebral extraction of oxygen and intracranial pressure, along with other monitoring modalities. Interventions : Routine neuroemergency procedures. Measurements and Main Results : Cerebral extraction of oxygen (arteriojugular oxyhemoglobin saturation difference) was measured in each patient, early in the acute phase (2 to 8 hrs postinjury). Outcome at 6 months postinjury was significantly better in patients with initially increased cerebral extraction of oxygen (>42%) than In those patients with normal (24% to 42%) or decreased (<24%) values. In contrast, no significant differences were found among these three groups with respect to age, initial Glasgow Coma Scale score, intracranial pressure, cerebral perfusion pressure, Paco 2 , total hemoglobin content, and time from injury when the initial measurements were performed. Conclusions : Initially increased cerebral extraction of oxygen appears to Indicate global cerebral viabillty rather than cerebral ischemia in patients with acute traumatic diffuse brain swelling.
Efficiency in generalized pipeline networks

A common architecture of most of today's super machines revolves around parallel or pipeline processing. Typical examples of such machines are the CDC STAR-100, TI-ASC, PEPE, IBM 360/91, 360/195, and CDC 6600, 7600, etc. They all have distinct pipeline processing capabilities, either in the form of internally pipelined arithmetic functional units or in the form of a pipeline of special purpose functional units. The principal idea behind pipelining is to create as much overlap as possible in the operations of the different facilities, for example, memory fetch unit, decoding units, adders, and multipliers. Concurrency of different operations increases the system utilization. As an important consequence of concurrency, the execution speed of most jobs are accelerated considerably as is evidenced in systems like 360/195 and TI-ASC. Ideally, in a pipelined machine, instead of obtaining one output per major cycle from the system, a rate of one output per minor cycle may be achievable. A typical linear pipeline is as drawn in Figure 1(a).
Promotion, Turnover, Earnings, and Firm‐Sponsored Training

I develop a model in which different technological conditions lead to distinct equilibria with different patterns in labor mobility, promotion, earning distribution, and provision of firm‐sponsored training. Key is the asymmetric learning of workers’ characteristics. Because of the information that is conveyed to the market by promotion, firms have incentives to adopt strategic promotion policies, which result in different patterns in the use of internal labor market. The theory explains well the differences between the Japanese and the United States labor markets.
Tandem Dienone-Photorearrangement-Cycloaddition for the Rapid Generation of Molecular Complexity

A tandem dienone photorearrangement–cycloaddition (DPC) reaction of novel cyclohexadienone substrates tethered with various 2π and 4π reaction partners resulted in the formation of polycyclic, bridged frameworks. In particular, use of alkynyl ether-tethered substrates led to (3 + 2) cycloaddition to afford strained alkenes which could be further elaborated by intra- and intermolecular cycloaddition chemistry to produce complex, polycyclic chemotypes.
Rocket engine diagnostics using qualitative modeling techniques

Researchers at NASA Lewis Research Center are presently developing qualitative modeling techniques for automated rocket engine diagnostics. A qualitative model of a turbopump interpropellant seal system has been created. The qualitative model describes the effects of seal failures on the system steady-state behavior. This model is able to diagnose the failure of particular seals in the system based on anomalous temperature and pressure values. The anomalous values input to the qualitative model are generated using numerical simulations. Diagnostic test cases include both single and multiple seal failures.
Multimode fiber amplifier with tunable modal gain using a reconfigurable multimode pump

We propose a method for controlling mode-dependent gain in a multimode Erbium-doped fiber amplifier by tuning the mode content of a multimode pump. The resulting device is suitable for mode-division multiplexed transmission.
Structural Airway Anomalies in Patients with DiGeorge Syndrome: A Current Review

DiGeorge Syndrome is a genetic disorder characterized by either absence or hypoplasia of the thymus and the parathyroid glands. Patients with this syndrome also have a high incidence of cardiovascular malformations and facial dysmorphism. Structural airway anomalies have also been described, albeit infrequently. Tracheoesophageal fistula, short trachea with reduced numbers of tracheal rings, abnormal thyroid cartilage, laryngomalacia, tracheomalacia, and bronchomalacia have been recognized in these patients. We review all previously reported patients with DiGeorge syndrome and lower airway anomalies. In addition, we present 2 patients with DiGeorge syndrome who were each found to have an aberrant right tracheal bronchus. Structural airway anomalies can be a cause of morbidity and mortality in patients with DiGeorge syndrome. Prompt, thorough evaluation of the upper and lower airway in these patients is essential.
True liquid cooling of computers

True Liquid Cooling means removing the heat from the heat source with a liquid instead of just pre-chilling air with cold water. One of the major advantages of True Liquid Cooling over pre-chilling air is that the heat may be rejected from the internal liquid into either chilled water or computer room air, at the option of the customer.The basic problem, which must be solved in order to achieve such a cooling system, is to get the liquid to and from the heat source without getting everything else wet. This paper describes how this is accomplished for both multichip integrated circuit packages and high wattage power supplies. Also, described is the implementation of a True Liquid Cooling system for a large central processor.
Near-surface heating on Enceladus and the south polar thermal anomaly

[1] Strike-slip motion is predicted to be a consequence of diurnal tidal stresses in most satellites of the outer solar system. Such motion can lead to near-surface heating through friction or viscous dissipation. Here we discuss the effect of near-surface shear heating on convection in the underlying ice shells of icy satellites. We present models of convection in spherical shells including tidal and shear heating, and show that localized near-surface heating enhances convective upwelling beneath it. The near-surface heating promotes regional melting of the ice shell, which likely results in subsidence of the surface topography. The long-wavelength geoid resulting from the subsidence, plume buoyancy and dynamic topography may lead to small (≲4° per Ma) amounts of true polar wander, potentially contributing to the south polar location of the observed thermal anomaly. However compositional effects are likely required in addition to thermal effects to generate larger degrees of reorientation.
Depolarization of radiation by non-absorbing foams

A Monte Carlo/Ray-Tracing technique is developed to investigate the depolarization of radiation by foams simulated as layers of air-bubble-laden substrates. Angular and radial profiles of reflection and transmittance are predicted for one-dimensional media subjected to a collimated, polarized light beam. The effects of different bubble sizes, separation distance distributions between bubbles, and medium thickness are considered. Fresnel reflections at the boundaries of bubbles are accounted for using a ray-tracing approach. Calculations are performed to determine vertical and horizontal polarization components of both radial and angular profiles of reflection and transmission. It is shown that if the polarized reflection and transmission data can be obtained from carefully conducted experiments, they can be effectively used to diagnose the changes in the structure of foams.
Stereocontrol in N-Directed Hydroboration: Synthesis of Amino Alcohols Related to the Piperidine Alkaloids

Treatment of 2-(2′-alkenyl)-piperidine boranes with iodine or triflic acid induces internal hydroboration with high regiocontrol, even with a terminal alkene (R = H). Good stereocontrol is possible for the N-benzyl substrates. Comparisons with acyclic model structures show that the source of regiocontrol with the terminal alkene is due to a steric effect of the axial piperidine C(3,5) hydrogens that destabilize the competing bridged bicyclic transition state.
Synthesis of Substituted Pyridine Derivatives via the Ruthenium-Catalyzed Cycloisomerization of 3-Azadienynes

We describe a two-step conversion of various N-vinyl and N-aryl amides to the corresponding substituted pyridines and quinolines, respectively. The process involves the direct conversion of amides, including sensitive N-vinyl amides, to the corresponding trimethylsilyl alkynyl imines followed by a ruthenium-catalyzed protodesilylation and cycloisomerization. A wide range of new alkynyl imines are prepared and readily converted to the corresponding azaheterocycles.
Solvability of linear equations within weak mixing sets

We introduce a new class of “random“ subsets of natural numbers, WM sets. This class contains normal sets (sets whose characteristic function is a normal binary sequence). We establish necessary and sufficient conditions for solvability of systems of linear equations within every WM set and within every normal set. We also show that any partition-regular system of linear equations with integer coefficients is solvable in any WM set.
The DEEP2 Galaxy Redshift Survey: Clustering of Galaxies as a Function of Luminosity at z = 1

We measure the clustering of DEEP2 galaxies at z = 1 as a function of luminosity on scales 0.1-20 h-1 Mpc. Drawing from a parent catalog of 25,000 galaxies at 0.7 L*, have a steeper slope. The clustering scale length, r0, varies from 3.69 ± 0.14 for the faintest sample to 4.43 ± 0.14 for the brightest sample. The relative bias of galaxies as a function of L/L* is steeper than the relation found locally for SDSS galaxies by Zehavi et al. in 2005 over the luminosity range that we sample. The absolute bias of galaxies at z ~ 1 is scale dependent on scales rp < 1 h-1 Mpc, and rises most significantly on small scales for the brightest samples. For a concordance cosmology, the large-scale bias varies from 1.26 ± 0.04 to 1.54 ± 0.05 as a function of luminosity and implies that DEEP2 galaxies reside in dark matter halos with a minimum mass of ~ × 1012 h-1 M☉.
Influence of Grain Size on Ferroelastic Toughening and Piezoelectric Behavior of Lead Zirconate Titanate

Lead zirconate titanate specimens, at composition Zr 48.9±1.0 /Ti 51.1±1.0 , of grain sizes ranging from 0.5 to 15 μm were prepared by hot pressing. The fracture toughness showed a 40% increase in the fine-grained specimens. Poling produced anisotropy in the fracture toughness. A tensor representation for the fracture toughness, now a function of the crack plane normal and the poling direction, is developed. The maximum and minimum values in the toughness tensor are shown to be related to the unpoled toughness by a simple phenomenological relationship. We also find that the piezoelectric coefficient, d 33 , shows a slight increase for the fine-grained specimens, which is in conflict with the general view that smaller-grained materials can sustain vanishingly small values of spontaneous polarization.
Assessment of Triton Potential Energy

An assessment is made of the dominant features contributing to the triton potential energy, with the objective of understanding qualitatively their origins and sensitivities. Relativistic effects, short-range repulsion, and OPEP dominance are discussed. A determination of the importance of various regions of nucleon-nucleon separation is made numerically.
Multidimensional chromatography coupled to electrospray ionization time-of-flight mass spectrometry as an alternative to two-dimensional gels for the identification and analysis of complex mixtures of intact proteins.

Abstract The limitations of 2-D gels for global proteomics have encouraged the development of alternative approaches for identifying proteins in complicated mixtures, and determining their modification state. In this work, we describe the application of multidimensional liquid chromatography (SCX-RPLC) coupled with electrospray time-of-flight mass spectrometry and off-line fraction collection to analyze complex intact protein mixtures. Methods were developed using both standard proteins and an enriched yeast ribosomal fraction sample containing ∼100 proteins, which permitted assessment of the effectiveness of the individual separation dimensions, as well as investigation of the interplay between separation capacity and electrospray MS performance.
Does a Rising Biofuels Tide Raise All Boats? A Study of Cash Rent Determinants for Iowa Farmland under Hay and Pasture

Iowa's farmland consists of over 16% hay crops and pastureland, a significant portion of which is under cash rental contracts. This study investigates the comparative relationships between cash rental rates for cropped land and non-cropped land, where the latter includes hay and pastureland. We find that higher crop prices resulting from biofuel demand induces land use conversion from non-cropped land to crop production and thus bids up non-cropped land rents. Compared with changes in cropped land cash rents, non-cropped farmland rents could increase by a higher percentage. Non-cropped land cash rental rates are largely determined by crop and feeder cattle prices, population density, soil quality, and proportion of non-cropped land in a specific area. A primary effect of ethanol subsidies is the redistribution of income between corn growers and livestock producers, whereby higher livestock feed costs together with increasing hay and pastureland cash rents harm the dairy and feedlot beef sectors. Our study shows that, because of the positive effect on rents, the policies have an indeterminate effect on landowners operating in the cow-calf sector.