cssi/SciSciGPT-SciSciNet huggingface dataset:
Metric Combinatorics of Convex Polyhedra: Cut Loci and Nonoverlapping Unfoldings

Let S be the boundary of a convex polytope of dimension d+1, or more generally let S be a convex polyhedral pseudomanifold. We prove that S has a polyhedral nonoverlapping unfolding into ${\Bbb{R}}^{d}$, so the metric space S is obtained from a closed (usually nonconvex) polyhedral ball in ${\Bbb{R}}^{d}$ by identifying pairs of boundary faces isometrically. Our existence proof exploits geodesic flow away from a source point v∈S, which is the exponential map to S from the tangent space at v. We characterize the cut locus (the closure of the set of points in S with more than one shortest path to v) as a polyhedral complex in terms of Voronoi diagrams on facets. Analyzing infinitesimal expansion of the wavefront consisting of points at constant distance from v on S produces an algorithmic method for constructing Voronoi diagrams in each facet, and hence the unfolding of S. The algorithm, for which we provide pseudocode, solves the discrete geodesic problem. Its main construction generalizes the source unfolding for boundaries of three-polytopes into ${\Bbb{R}}^{2}$. We present conjectures concerning the number of shortest paths on the boundaries of convex polyhedra, and concerning continuous unfolding of convex polyhedra. We also comment on the intrinsic nonpolynomial complexity of nonconvex manifolds.
Fractal character of the auditory neural spike train

Long-counting-time pulse-number distributions (PNDs) were measured from a broad variety of cat primary auditory fibers using different tone and noise stimuli, counting times T, and number of samples N/sub T/. Whereas short-counting-time PNDs (T approximately 50 ms) manifest the presence of spike pairs (an enhancement of even- over odd-count probabilities), the irregular shapes of the long-counting-time PNDs (T>or approximately=0.1 s) reveal that the underlying sequence of action potentials consists of spike clusters when viewed on a longer time scale. For all units measured, the count variance-to-mean ratio (Fano factor) F(T) varied little over some 90 dB change in the stimulus level. On the other hand, F(T) increased substantially as T and/or N/sub T/ were increased, corresponding to the capture of larger and larger spike clusters in the counting time. A relationship is developed between the Fano-time function F(T) and the normalized coincidence rate function, g ( tau ) versus delay time tau . The behavior of the PNDs and the scale invariance implicit in fractional-power-law relationships suggest that the neural events on all primary auditory fibers exhibit fractal behavior for sufficiently large times (sufficiently low frequencies). >
The Value in Targeting Institutional Investors: Evidence from the Five‐or‐Fewer Rule Change

This article examines a recent relaxation in the ownership qualifications for real estate investment trusts that is popularly referred to as the five-or-fewer rule change. The motivation for this rule change leads to an analogy between the ownership change process and an industry-wide investor targeting strategy. The findings reveal a significant wealth effect based on the targeting strategy; however, there is no evidence to suggest this heterogeneous effect was intended. In addition, the targeted investors' ex post trading behavior is linked directly to the targeting strategy. These findings support the value-based strategy of targeting institutional investors where, in this case, value creation is associated with the increased concentration of a dispersed base of sophisticated investors.
Vibrational energy redistribution and relaxation in the photoisomerization of cis‐stilbene

Trans‐stilbene photoproduces appearing from the photoisomerization of cis‐stilbene within 150 fs are observed to be vibrationally hot, but with a nonthermal population distribution. The product electronic spectrum depends on the incident photon energy. Clearly, intramolecular vibrational energy redistribution is not ultrafast.
Aerodynamic and functional consequences of wing compliance

A growing body of evidence indicates that a majority of insects experience some degree of wing deformation during flight. With no musculature distal to the wing base, the instantaneous shape of an insect wing is dictated by the interaction of aerodynamic forces with the inertial and elastic forces that arise from periodic accelerations of the wing. Passive wing deformation is an unavoidable feature of flapping flight for many insects due to the inertial loads that accompany rapid stroke reversals—loads that well exceed the mean aerodynamic force. Although wing compliance has been implicated in a few lift-enhancing mechanisms (e.g., favorable camber), the direct aerodynamic consequences of wing deformation remain generally unresolved. In this paper, we present new experimental data on how wing compliance may affect the overall induced flow in the hawkmoth, Manduca sexta. Real moth wings were subjected to robotic actuation in their dominant plane of rotation at a natural wing beat frequency of 25 Hz. We used digital particle image velocimetry at exceptionally high temporal resolution (2,100 fps) to assess the influence of wing compliance on the mean advective flows, relying on a natural variation in wing stiffness to alter the amount of emergent deformation (freshly extracted wings are flexible and exhibit greater compliance than those that are desiccated). We find that flexible wings yield mean advective flows with substantially greater magnitudes and orientations more beneficial to lift than those of stiff wings. Our results confirm that wing compliance plays a critical role in the production of flight forces.
Nuclear Surface Oscillations

The extreme shell model of the nucleus is extended by allowing the last odd nucleon to interact with collective modes of motion of the even-even nuclear core. The interaction between a nucleon and the surface oscillations of the core was given by Bohr and is employed here with a Fock space representation for the core excitation. Because of the interaction neither the nucleon nor the core conserve their angular momentum, but the total angular momentum is conserved. The problem is treated by the Tamm-Dancoff method. In terms of the Tamm-Dancoff wave function, formulas are derived for the magnetic moment and the quadrupole moment of an odd nucleus. The energy of excitation of the core is taken empirically from the first excited state of the corresponding even-even nucleus. With this procedure all the parameters of the theory are fixed. The magnetic moment deviations calculated in this manner agree with experiment for nuclei in which the total angular momentum is one half, but the agreement does not exist for higher angular momenta. It is also possible to obtain a qualitative fit for the large quadrupole moments of nuclei with odd numbers of nucleons between fifty and eighty-two. The problem of two equivalent nucleons outside a closed shell is treated in the same manner, and it is shown that the first and second excited states have spins 2 and 4 as usually observed. In addition there is a pairing energy binding effect in the ground state which is larger when the individual angular momenta of the two nucleons is larger. This is the pairing energy rule usually employed in shell model calculations.
A Framework for Drawing Planar Graphs with Curves and Polylines

We describe a unified framework of aesthetic criteria and complexity measures for drawing planar graphs with polylines and curves. This framework includes several visual properties of such drawings, including aspect ratio, vertex resolution, edge length, edge separation, and edge curvature, as well as complexity measures such as vertex and edge representational complexity and the area of the drawing. In addition to this general framework, we present algorithms that operate within this framework. Specifically, we describe an algorithm for drawing any n-vertex planar graph in an O(n)×O(n) grid using polylines that have at most two bends per edge and asymptotically-optimal worst-case angular resolution. More significantly, we show how to adapt this algorithm to draw any n-vertex planar graph using cubic Bezier curves, with all vertices and control points placed within an O(n)×O(n) integer grid so that the curved edges achieve a curvilinear analogue of good angular resolution. All of our algorithms run in O(n) time.
N-Allylation of anilides with chiral palladium catalysts: the first catalytic asymmetric synthesis of axially chiral anilides

The first catalytic asymmetric synthesis of axially chiral anilides has been carried out under palladium-catalyzed allylation reaction conditions with chiral phosphine ligands. Allylation of anilides bearing an ortho tert-butyl group with a palladium catalyst and (S)-BINAP as a chiral ligand gave axially chiral anilides in about 50% ee.
Multifrequency studies of the enigmatic gamma-ray source 3EG J1835+5918

The EGRET telescope aboard the NASA Compton Gamma-Ray Observatory (CGRO) has repeatedly detected 3EG J1835+5918, a bright and steady source of high-energy gamma-ray emission which has not yet been identified. The absence of any likely counterpart for a bright gamma-ray source located 25° off the Galactic plane initiated several attempts of deep observations at other wavelengths. We report on counterparts in X-rays on a basis of a 60-ks ROSAT HRI image. In order to conclude on the plausibility of the X-ray counterparts, we reanalysed data from EGRET at energies above 100 MeV and above 1 GeV, including data up to CGRO observation cycle 7. The gamma-ray source location represents the latest and probably the final positional assessment based on EGRET data. We especially address the question of flux and spectral variability, here discussed using the largest and most homogeneous data set available at high-energy gamma-rays for many years. The results from X-ray and gamma-ray observations were used in a follow-up optical identification campaign at the 2.2-m Guillermo Haro Telescope at Cananea, Mexico. VRI imaging has been performed at the positions of all of the X-ray counterpart candidates, and spectra were taken where applicable. The results of the multifrequency identification campaign toward this enigmatic unidentified gamma-ray source are given, especially on the one object which might be associated with the gamma-ray source 3EG J1835+5918. This object has the characteristics of an isolated neutron star and possibly of a radio-quiet pulsar.
Palladium-Catalyzed Direct Functionalization of Imidazolinone: Synthesis of Dibromophakellstatin

The direct C−H functionalization of imidazolinone is achieved with Pd(OAc)2/NaOAc in DMSO. Dibromophakellstatin can be synthesized in five steps with 40% overall yield using this new C−H activation method.
PRECURSORS SEE INSIDE BLACK HOLES

We consider, within a string theoretic context, the accessibility of events inside a black hole horizon. We present a gedankenexperiment which uses the nonlocal nature of precursors in the AdS/CFT correspondence, as well as the global nature of event horizons, to argue that the dual field theory does contain information about physics inside black holes. This alleviates the causal obstacles to accessing behind-the-horizon physics, thereby rendering more tractable certain long-standing questions of quantum gravity, such as the information paradox and possibly even singularity resolution.
Measurement and Analysis of Gas Bubbles near a Reference Electrode in Aqueous Solutions

Bubble size distributions (BSDs) near a reference electrode (RE) in aqueous glycerol solutions of an electrolyte NaCl have been investigated under various gas superficial velocities (Us). BSD and voltage reading of the solution were measured by using a high-speed digital camera and a pH/voltage meter, respectively. The results show that bubble size (b) increases with liquid viscosity (μc) and Us. Self-similarity is seen and can be described by the log-normal form of the continuous number frequency distribution. The result shows that b controls the voltage reading in each solution. As b increases, the voltage increases because of gas bubbles interrupting their electrolyte paths in the solutions. An analysis of bubble rising velocity reveals that Stokes' Law should be used cautiously to describe the system. The fundamental equation for bubble formation was developed via Newton's second law of motion and shown to be the function of three dimensionless groupsWeber number, Bond number, and Capillary number. Af...
Dynamic Bargaining in a Supply Chain with Asymmetric Demand Information

We analyze a dynamic bargaining game in which a seller and a buyer negotiate over quantity and payment to trade for a product. Both firms are impatient, and they make alternating offers until an agreement is reached. The buyer is privately informed about his type, which can be high or low: the high type's demand is stochastically larger than the low type's. In the dynamic negotiation process, the seller can screen, whereas the buyer can signal information through their offers, and the buyer has an endogenous and type-dependent reservation profit. With rational assumptions on the seller's belief structure, we characterize the perfect Bayesian equilibrium of the bargaining game. Interestingly, we find that both quantity distortion and information rent may be avoided depending on the firms' relative patience, and the seller may reach an agreement with either the high type or the low type first, or with both simultaneously. Furthermore, we explore our model to characterize the effect of demand forecasting accuracy on firm profitability. We find that improved demand forecast benefits the buyer but hurts the seller when the buyer's forecasting accuracy is low. However, once the buyer's forecasting accuracy exceeds a threshold, both firms will benefit from further improvement of the forecast. This observation makes an interesting contrast to previous findings based on the one-shot principal--agent model, in which improvement of forecasting accuracy mostly leads to a win--lose outcome for the two firms, and the buyer has an incentive to improve his forecasting accuracy only when it is extremely low. This paper was accepted by Yossi Aviv, operations management.
Preoperative chemotherapy for esophageal cancer with paclitaxel and carboplatin: results of a phase II trial☆

Abstract Objective Paclitaxel has one of the highest response rates when used as a single agent in patients with esophageal cancer. The combination of paclitaxel and carboplatin has been shown to be a well-tolerated and safe regimen in non–small cell lung cancer. The objective of this study was to determine the efficacy of preoperative paclitaxel and carboplatin in patients with carcinoma of the esophagus. Patients and methods A phase II trial was initiated in January 1999 and concluded in January 2001. All patients had potentially resectable disease (including clinical T4 lesions). Patients with stage I disease and those with visceral metastases were excluded. All underwent preoperative computed tomography scanning and endosonography for staging. Paclitaxel (200 mg/m 2 ) and carboplatin (area under the curve=6) were given on days 1 and 22. Esophagectomy was carried out on weeks 6 to 8. Results Twenty-six (11 epidermoid, 15 adenocarcinoma) patients completed the trial. Median age was 61.5 and 85% were men. Preoperative staging showed: stage IIA, 6 patients; stage IIB, 1 patient; and stage III, 19 patients. All patients completed their preoperative chemotherapy. There was no unexpected chemotherapy-related toxicity. A major clinical response was achieved in 16 patients (61%: 19% complete, 42% partial). Resectability was 77% (20/26). A complete pathologic response was seen in 11% of all patients and in 25% of those with epidermoid cancer. Hospital mortality and morbidity were 4 and 27%, respectively. Overall 3-year survival was 48% (64% for resected patients, median not reached). All 6 unresectable patients died within 6 months of exploration. Conclusion Paclitaxel-carboplatin combination is a safe and well-tolerated regimen for esophageal cancer with clinical response rates comparable to historical controls. This regimen may be especially suitable for patients with epidermoid cancer, who had a 25% pathological complete response in this report.
The Effect of Stellar Evolution on SiC Dust Grain Sizes

Stars on the asymptotic giant branch (AGB) produce dust in their circumstellar shells. The nature of the dust-forming environment is influenced by the evolution of the stars, in terms of both chemistry and density, leading to an evolution in the nature of the dust that is produced. Carbon-rich AGB stars are known to produce silicon carbide (SiC). Furthermore, observations of the ~11 μm SiC feature show that the spectral features change in a sequence that correlates with stellar evolution. We present new infrared spectra of amorphous SiC and show that the ~9 μm feature seen in both emission and absorption, and correlated with trends in the ~11 μm feature, may be due to either amorphous SiC or nanocrystalline diamond with a high proportion of Si substituting for C. Furthermore, we identify SiC absorption in three ISO spectra of extreme carbon stars, in addition to the four presented by Speck and coworkers. An accurate description of the sequence in the IR spectra of carbon stars requires accounting for both SiC emission and absorption features. This level of detail is needed to infer the role of dust in the evolution of carbon stars. Previous attempts to find a sequence in the infrared spectra of carbon stars considered SiC emission features while neglecting SiC absorption features, leading to an interpretation of the sequence that inadequately describes the role of dust. We show that the evolutionary sequence in carbon star spectra is consistent with a grain size evolution such that dust grains get progressively smaller as the star evolves. The evolution of the grain sizes provides a natural explanation for the shift of the ~11 μm SiC feature in emission and in absorption. Further evidence for this scenario is seen in both post-AGB star spectra and in meteoritic studies of presolar grains.
Photoinduced electron transfer in molecular systems: Recent developments

Highlights of new findings in electron transfer studies, in which elegant synthetic model systems were used to address important fundamental questions, are briefly described. The selected examples include: (i) efficient long distance electron transfer mediated by hydrogen bonds; (ii) energy and electron transfer through the walls of hemicarcerands; (iii) the influence of internal electric fields on the rate of electron transfer in α-helical peptides; (iv) construction of a biomimetic proton pump driven by photoinduced electron transfer. The review underscores the increasing role of synthesis in modern physical chemistry research.
Ammonia Borane as a Hydrogen Carrier: Dehydrogenation and Regeneration

Interest in sustainable non-hydrocarbon-based fuels for transportation has grown as the realization that the supply of fossil fuels is limited and the deleterious environmental effects of burning them has come into public focus. The use of hydrogen (H2) has been proposed as an alternative, but its use in pure form is undesirable due to the high pressures or low temperatures required to store useful quantities. Approaches to ameliorate this issue, which stem from the low volumetric energy density of H2, include the pursuit of sorbents capable of containing H2 in greater density than liquid H2 at reasonable temperatures and pressures, metal hydrides such as NaBH4, and chemical hydrides such as ammonia borane (AB, NH3BH3). AB contains 19.6 wt.-% H2, which is well suited to practical applications, but issues with extracting the optimal quantities of H2 at reasonable temperatures and at useful rates as well as recycling of the spent fuel back into AB with good efficiency and reasonable cost remain to be solved. These problems are inextricably intertwined, as the needs of the regeneration process dictate which catalysts are used (i.e. what kind of spent fuel is generated). This Microreview focuses on recent developments in transition metal complexes for the catalytic dehydrogenation of AB. Neither solvolysis of AB nor thermolysis of AB in the absence of a catalyst are covered in this review.
The imperfection of protection through detection and intervention. Lessons from three decades of research on the psychiatric assessment of violence risk

As I began writing this article, 1 a “shooting rampage” at a West Palm Beach Wendy's restaurant was the latest nationally publicized instance in which an emotionally troubled individual used a fire...
Spontaneous Raman spectroscopy of shocked H2O

Abstract We have developed a new Raman spectroscopic system for recording spontaneous Raman spectra from shocked matter at high pressure and temperature during shock passage. This system has been applied to the study of the OH-stretch band of water shocked to pressures between 7.5 and 25.7 GPa. The spectra indicate that strong intermolecular hydrogen-bonding persists to 12 GPa and decreases in strength at higher pressures. A two-component mixture model fits the data well under shock conditions.
Topology optimization of compliant mechanical amplifiers for piezoelectric actuators

A method for the design of displacement amplifying compliant mechanisms for piezoelectric actuators is developed using a topology optimization approach. The overall stroke amplification or geometric advantage of the mechanism, and the overall mechanical efficiency of the mechanism are considered as objective functions. The maximization of these objective functions is accomplished using two different solution methods, Sequential Linear Programming and an Optimality Criteria method. The focus of this paper is on the underlying topology optimization problem formulations and the solution methods. Design examples are presented which illustrate the method, with comparisons of the computation time and mechanism performance for the two formulations and solution methods. A procedure has also been developed to automatically convert the topology optimization results to a solid CAD model. A prototype design has been fabricated to serve as proof of concept.
Triplet Excitation Energy Transfer with Constrained Density Functional Theory

We study the electronic coupling matrix element for triplet excitation energy-transfer processes with a number of different computational methods. For the first time, constrained density functional theory (CDFT) is applied to the problem of energy transfer, and results are compared with direct coupling calculations of broken symmetry and fragment densities, as well as the splitting method. A naive calculation of the electronic coupling using diabatic and adiabatic energy differences is shown to yield erroneous results due to the fractional spin error present in both Hartree-Fock and commonly used DFT exchange-correlation functionals. Some potential issues concerning the splitting method with triplet references within Hartree-Fock and DFT are discussed. We find that only methods that compute the matrix element directly (either from CDFT, broken symmetry, or fragment states) appear to be robust. Several illustrative examples are presented.
The Redshift Distribution of Distant Supernovae and Its Use in Probing Reionization

We model the number of detectable supernovae (SNe) as a function of redshift at different flux thresholds, making use of the observed properties of local SNe, such as their light curves, fiducial spectra, and peak magnitude distributions. We assume that the star formation rate (SFR) at high redshift traces the formation rate of dark matter halos. We obtain a rate of 0.4-2.3 SNe arcmin-2 yr-1 at z 5 at the near-infrared (4.5 ?m) flux density threshold of 3 nJy (achievable with the James Webb Space Telescope [JWST] in a 105 s integration). In a hypothetical 1 yr survey, it should be possible to detect up to several thousand SNe per unit redshift at z ~ 6. We discuss the possible application of such a large sample of distant SNe as a probe of the epoch of reionization. By heating the intergalactic medium (IGM) and raising the cosmological Jeans mass, the process of reionization can suppress star formation in low-mass galaxies. This could have produced a relatively sharp drop in the SN rate around the redshift of reionization (zre). We quantify the detectability of this feature in future surveys of distant SNe by varying the redshift and duration of reionization, as well as its impact on the SFR in low-mass halos, which results in different redshifts, widths, and sizes of the drop in the expected SFR. We find that the drop can be detected out to zre ~ 13, as long as (1) the reionization history contains a relatively rapid feature that is synchronized over different regions to within ?z 1-3, (2) the star formation efficiency in halos that dominate reionization is * ~ 10%, and (3) reionization significantly suppresses the star formation in low-mass halos. Depending on the details of (1)-(3), this could be achieved with a survey lasting less than 2 weeks. Detecting this signature would also help elucidate the feedback mechanism that regulates reionization.
Generalized $\beta$-expansions, substitution tilings, and local finiteness

For a fairly general class of two-dimensional tiling substitutions, we prove that if the length expansion β a Pisot number, then the tilings defined by the substitution must be locally finite. We also give a simple example of a two-dimensional substitution on rectangular tiles, with a non-Pisot length expansion β, such that no tiling admitted by the substitution is locally finite. The proofs of both results are effectively one-dimensional and involve the idea of a certain type of generalized β-transformation.
Gamma-Ray Bursts: Jets and Energetics

Abstract The relativistic outflows from gamma-ray bursts are now thought to be narrowly collimated into jets. After correcting for this jet geometry there is a remarkable constancy of both the energy radiated by the burst and the kinetic energy carried by the outflow. Gamma-ray bursts are still the most luminous explosions in the Universe, but they release energies that are comparable to supernovae. The diversity of cosmic explosions appears to be governed by the fraction of energy that is coupled to ultra-relativistic ejecta.
An exploration of the positive effect of inequality on common property forests

Abstract This paper analyzes the household level forces driving the positive impact of inequality on common property forest cover in Mexico. A game theoretic model demonstrates that when common property goods are complementary to private inputs in production, an increase in wealth inequality can lead to a decrease in exploitation of the commons. Data from 350 Mexican common properties show that as inequality increases, those on the lower end of the land distribution are less likely to use the commons. The data also show a negative correlation between inequality and poverty. Alternative hypotheses for these results are considered.
Emergence of a quasar outflow

We report the first discovery of the emergence of a high-velocity broad-line outflow in a luminous quasar, J105400.40+034801.2, at redshift z∼ 2.1. The outflow is evident in ultraviolet C iv and Si iv absorption lines with velocity shifts v∼ 26 300 km s−1 and deblended widths FWHM ∼4000 km s−1. These features are marginally strong and broad enough to be considered broad absorption lines (BALs), but their large velocities exclude them from the standard BAL definition. The outflow lines appeared between two observations in the years 2002.18 and 2006.96. A third observation in 2008.48 showed the lines becoming ∼40 per cent weaker and 10 to 15 per cent narrower. There is no evidence for acceleration or for any outflow gas at velocities ≲23 000 km s−1. The lines appear to be optically thick, with the absorber covering just 20 per cent of the quasar continuum source. This indicates a characteristic absorber size of ∼4 × 1015 cm, but with a BAL-like total column density log NH(cm−2) ≳ 21.2 and average space density nH≳ 2 × 105 cm−3. We attribute the emergence of the outflow lines to a substantial flow structure moving across our line of sight, possibly near the ragged edge of the main BAL flow or possibly related to the onset of a BAL evolutionary phase.
The design of single-stranded nucleic acid knots

A general strategy is described for the synthesis of single-stranded nucleic acid knots. Control of nucleic acid sequence is used to direct the formation of secondary structures that produce the target topology. The key feature of the strategy is the equation of a half-turn of double helical DNA or RNA with a node in a knot. By forming nodes from complementary DNA sequences, it appears possible to direct the assembly of any simple knot. Stabilization of individual nodes may be achieved by constructing them from long regions containing both B-DNA and Z-DNA. Control over the braiding of DNA that acts as a link between node-forming domains can be realized by condensing the nodes into well-defined DNA structures, such as extended domains of linear duplex, branched junctions, antijunctions or mesojunctions. Further topological control may be derived from the pairing of linker regions to complementary single-stranded molecules, thereby preventing them from braiding in an undesirable fashion.
The Influence of Twist on the Motion of Straight Elliptical Jets.

This paper is concerned with a fairly detailed analysis of the motion of a straight elliptical jet of an incompressible, inviscid fluid in which the jet is allowed to twist along its axis. Our study, which includes the effects of gravity and surface tension, utilizes the nonlinear differential equations of the one-dimensional theory of a directed fluid jet. A number of theorems are proved pertaining to the motion of a twisted elliptical jet and some special solutions are obtained which illustrate the influence of twist.
Influence of bottom quark jet quenching on single electron tomography of Au + Au

High transverse momentum single (non-photonic) electrons are shown to be sensitive to the stopping power of both bottom, b, and charm, c, quarks in AA collisions. We apply the DGLV theory of radiative energy loss to predict c and b quark jet quenching and compare the FONLL and PYTHIA heavy flavor fragmentation and decay schemes. We show that single electrons in the p{sub T} = 5-10 GeV range are dominated by the decay of b quarks rather than the more strongly quenched c quarks in Au+Au collisions at {radical}s = 200 AGeV. The smaller b quark energy loss, even for extreme opacities with gluon rapidity densities up to 3500, is predicted to limit the nuclear modification factor, R{sub AA}, of single electrons to the range R{sub AA} {approx} 0.5-0.6, in contrast to previous predictions of R{sub AA} {le} 0.2-0.3 based on taking only c quark jet fragmentation into account.
Matrix models on large graphs

Abstract We consider the spherical limit of multi-matrix models on regular target graphs, for instance single or multiple Potts models, or lattices of arbitrary dimension. We show, to all orders in the low temperature expansion, that when the degree of the target graph Δ → ∞, the free energy becomes independent of the target graph, up to simple transformations of the matter coupling constant. Furthermore, this universal free energy contains contributions only from those surfaces which are made up of “baby universes” glued together into trees, all non-universal and non-tree contributions being suppressed by inverse powers of Δ. Each order of the free energy is put into a simple, algebraic form.
Massive Field Stars and the Stellar Clustering Law

The distribution of N*, the number of OB stars per association or cluster, appears to follow a universal power-law form N in the local universe. We evaluate the distribution of N* in the Small Magellanic Cloud using recent broadband optical and space-ultraviolet data, with special attention to the lowest values of N*. We find that the power-law distribution in N* continues smoothly down to N* = 1. This strongly suggests that the formation of field massive stars is a continuous process with those in associations and that the field stars do not originate from a different star formation mode. Our results are consistent with the model that field massive stars represent the most massive members in groups of smaller stars, as expected if the clustering law applies to much lower masses as is expected from the stellar initial mass function (IMF). These results are consistent with the simultaneous existence of a universal IMF and a universal clustering law. Jointly, these laws imply that the fraction of field OB stars typically ranges from about 35% to 7% for most astrophysical situations, with an inverse logarithmic dependence on the most populous cluster, and hence on galaxy size and/or star formation rate. There are important consequences for global feedback effects in galaxies: field stars should therefore contribute proportionately to the volume of the warm ionized medium, and equal relative contributions by superbubbles of all sizes to the interstellar porosity are expected.
Probability distributions of line lattices in random media from the 1D Bose gas

Abstract The statistical properties of a two-dimensional lattice of elastic lines in a random medium are studied using the Bethe ansatz. We present a novel mapping of the dilute random line lattice onto the weak coupling limit of a pure Bose gas with delta-function interactions. Using this mapping, we calculate the cumulants of the free energy in the dilute limit exactly. The relation between density and displacement correlation functions in the two models is examined and compared with existing results from renormalization group and variational ansatze.
Asymmetric Nazarov Cyclizations.

The Nazarov cyclization1 is described as the 4 π electron conrotatory cyclization of a pentadienyl cation. The past 20 years have brought resurgent interest in this reaction most likely due to the realization that it can provide rapid and efficient access to multisubstituted cyclopentenones with excellent stereochemical control at two (or even three) contiguous ring carbon atoms.2 Typically, stoichiometric or super-stoichiometric Bronsted or Lewis acid is used to generate the conjugate acid 2 of pentadienone 1 reversibly (Scheme 1). 3 Electrocyclization subsequently leads to allylic cation 3 in which the trans relationship between substituents R2 and R4 is dictated by the conrotation. The process is normally terminated through proton loss from cation 3, leading typically either to cyclopentenone 4 or to 5, or to a mixture of the two. The trans stereochemistry between R1 and R2 in 4 or between R3 and R4 in 5 reflects the thermodynamically more stable product. The trans relationship between R2 and R4 in 3 can be preserved in the final product if loss of an exocyclic proton from R1 or R3 terminates the reaction. Scheme 1 Acid Catalyzed Conrotatory Cyclization. Several obstacles must be overcome in order to render such a process general and synthetically useful. Super-stoichiometric strong acids must be avoided so as to suppress undesired competing processes, e.g. Wagner-Meerwein rearrangements. The absolute stereochemistry of the product is determined by the absolute sense of conrotation: the stereochemistry indicated for 3 is a consequence of clockwise conrotation of 2, viewed from the bottom of the structure as it is shown in Scheme 1. Therefore in an enantioselective Nazarov cyclization the absolute sense of conrotation, or the torqoselectivity, must be controlled. The course of the termination step must also be controlled so as to avoid the production of isomeric mixtures of cyclopentenones. Some bias must be present to direct proton loss from 3 so that it does not take place indiscriminately. This Report will examine these constraints in the context of the asymmetric Nazarov cyclization. Enantioselective Nazarov cyclizations that employ asymmetric chiral effectors either catalytically or stoichiometrically will be examined, as well as processes in which transfer of chirality to the cyclic product takes place.
A Characterization of the Differential in Semi-infinite Cohomology

Semi-infinite cohomology is constructed from scratch as the proper generalization of finite dimensional Lie algebra cohomology. The differential d and other operators are realized as universal inner deri- vations of a completed algebra, which acts on any appropriate semi-infinite complex. In particular, d is shown to be the unique derivation satisfying the "Cartan identity" and certain natural degree conditions. The proof that d is square-zero may well be the shortest (arguably, the only) one in print.
Bargaining Ability and Competitive Advantage: Empirical Evidence from Medical Devices

In markets where buyers and suppliers negotiate, supplier costs, buyer willingness to pay, and competition determine only a range of potential prices, leaving the final price dependent on other fac...
Quantum cohomology of the Lagrangian Grassmannian

Let V be a symplectic vector space and LG be the Lagrangian Grassmannian which parametrizes maximal isotropic subspaces in V. We give a presentation for the (small) quantum cohomology ring QH∗ (LG) and show that its multiplicative structure is determined by the ring of Q-polynomials. We formulate a 'quantum Schubert calculus' which includes quantum Pieri and Giambelli formulas, as well as algorithms for computing the structure constants appearing in the quantum product of Schubert classes.
Efficiency of Magnetized Thin Accretion Disks in the Kerr Metric

The efficiency of thin disk accretion onto black holes depends on the inner boundary condition, specifically the torque applied to the disk at the last stable orbit. This is usually assumed to vanish. I estimate the torque on a magnetized disk using a steady magnetohydrodynamic inflow model originally developed by Takahashi et al. I find that the efficiency can depart significantly from the classical thin disk value. In some cases > 1, i.e., energy is extracted from the black hole.
Synthesis, characterization, and electronic structure of KV3Te3O0.42

Abstract KV3Te3O0.42 has been synthesized at 1173 K and its structure has been determined by single-crystal X-ray methods. The compound crystallizes in space group C6h2-P63/m of the hexagonal system with two formula units in a cell of dimensions a=9.62(2) A, c=4.48(1) A, V=359(1) A3 (T=113 K). The formula KV3Te3Ox, x=0.42(4), is derived from the X-ray data; combustion analysis for oxygen gives 0.18 0. The evidence for the presence of oxygen is strong, but not conclusive. For KV3Te3O0.42, Rw(Fo2)=0.080 for 358 observations and 19 variables, and R(F)=0.034 for 308 reflections having Fo2>2σ(Fo2). KV3Te3O0.42 crystallizes with the TlFe3Te3 structure, modified by addition of interstitial oxygen atoms at the centers of V6 octahedra. The structure comprises ∞1[V6Te6Ox2−] chains along c. The chains are separated by K+ cations that are coordinated to nine Te atoms in a tricapped trigonal prismatic arrangement. Two-probe resistivity measurements along the needle axis (c) show that KV3Te3O0.42 has a conductivity of 2.4(1)×10−2 Ω−1 cm−1 at room temperature. The magnetic susceptibility of KV3Te3O0.42 may be fit to the modified Curie–Weiss expression χ=χ0+C/(T+θ) with χ0=1.08(6)×10−3 emu mol−1, C=2.24(4)×10−2 emu K mol−1, and θ=−4.3(2) K, with μeff (300 K)=1.66(4) μB for each KV3Te3O0.42 unit. Extended Huckel band structure calculations on several structural models reveal that optimum metal–metal bonding is achieved with one oxygen atom in every second vanadium octahedron. From the band structure, a Peierls' distortion is predicted that may account for the semiconducting behavior.
Ar(alk)ylsulfonyl ethyl groups as phosphorus‐protecting functions

Various 2-[Ar(alk)ylsulfonyl]ethanols were prepared and subsequently converted into the corresponding phosphorodichloridites in almost quantitative yield via a convenient synthetic route. The versatility of the method, which obviates the necessity of a distillation step, is demonstrated by the preparation of other Ar(alk)yl phosphorodichloridites, including the unstable benzyl phosphorodichloridite.
Linear/nonlinear behavior in unsteady transonic aerodynamics

The accurate calculation of the aerodynamic forces in unsteady transonic flow requires the solution of the nonlinear flow equations. The aeroelastician, on the other hand, seeks to treat his problems (flutter, for example) by means of linear equations whenever possible. He may do this, even when the underlying flow is nonlinear, if the perturbation forces are linear over some (perhaps small) range of unsteady amplitude of motion. This paper assesses the range of parameters over which linear behavior occurs. In particular calculations are made for an NACA 64A006 airfoil oscillating in pitch over a range of amplitudes, frequencies, and Mach numbers. The primary aerodynamic method used is the well known LTRAN2 code of Ballhaus and Goorjian that provides a finite-difference solution to the low frequency, small disturbance, two-dimensional potential flow equation. Comparisons are made with linear subsonic theory, local linearization, and, for steady flow, with the full potential equation code of Bauer, Garabedian, and Korn.
The Halo Model and Numerical Simulations

Recently there has been a lot of attention focused on a virialized halo-based approach to understanding the properties of the matter and galaxy power spectrum. A key ingredient in this model is the number and distribution of galaxies within dark matter halos as a function of mass. This quantity has been predicted from semianalytic modeling and from fits to observational data. Here we present predictions for the occupation number and spatial distribution of subhalos based on a high-resolution hydrodynamical simulation including cooling, star formation, and feedback.
Gracilis Urethromyoplasty-An Autologous Urinary Sphincter for Neurologically Impaired Patients With Stress Incontinence

Bakken Research Center,Maastricht, The NetherlandsPurpose: To investigate the e•ect of a neurovascularly intact gracilis muscle urethral wrap, to beused to restore urinary continence as a transposed urinary sphincter graft, in patients withneurogenic lower urinary tract dysfunction. Methods: Five neurologically impaired men with adenervated and damaged urinary sphincter mechanisms were treated. The etiology ofsphincteric insu†ciency included sphincter denervation in three patients, external sphincter-otomy in one, and urethral trauma due to a chronic indwelling catheter in one. All patientsunderwent gracilis urethromyoplasty sphincter reconstruction. Two patients also underwentconcomitant ileocystoplasty and one patient ileocystostomy because of poor bladdercompliance and a bladder capacity of 5200 ml. Results: The gracilis urethromyoplastyfunctioned as a new autologous sphincter with follow-ups ranging from 6–35 months. Thesurgery was successful in four patients. Three of the four patients were managed withintermittent catheterization, and one managed by ileocystostomy. The ﬁfth patient continued torequire an indwelling urethral catheter. Conclusion: Gracilis urethromyoplasty achievescompression of the urethra using a neurovascularly intact muscle graft. The functional urethralclosure, obtained from the gracilis muscle wrap, assures dryness, and permits intermittent self-catheterization. It also avoids the risks of infection, erosion, or malfunction associated with theartiﬁcical urinary sphincter. The potential exists for electrical stimulation of this muscle graft toallow volitional control of the neo-sphincter mechanism, and voluntary voiding.Keywords: urinary incontinence; tissue transplantation; muscles; electric stimulation;urodynamic; spinal cord injury
Anomalous violation of conservation laws in Minkowski space

Abstract We consider the evolution of quantum Fermi fields in Minkowski gauge field backgrounds. Our motivation is the study of anomalous fermion number violating processes. We derive selection rules for fermion scattering amplitudes which relate the violation of fermionic charge to the change in winding between early and late times of the vacuum part of the gauge field. We find that the amount of fermion number violation is always integer, even when the topological charge of the gauge field is fractional. As an explicit example, we apply our results to spherically symmetric Minkowski solutions.
Morphological and frictional behavior of sputtered MoS2 films

Abstract From the texture and growth patterns of sputtered MoS 2 films deposited onto substrates, three regions can be distinguised: (1) a ridge formation region, (2) an equiaxed transition zone and (3) a columnar-fiber-like structure. The lubricating properties of sputtered MoS 2 films can be visually identified with respect to optical changes before and after rubbing. The orientation of the surface microcrystallites is identified, and the change in optical properties is explained. In sliding contact the sputtered film tends to break up at the base of the columnar region. Effective lubrication occurs with the film remaining on the substrate. This film is 0.18–0.22 microm thick.
WHAT IS THE "DAMAGES FUNCTION" FOR GLOBAL WARMING — AND WHAT DIFFERENCE MIGHT IT MAKE?

The existing literature on climate change offers little guidance on why one specification or another of a "damages function" has been selected. Ideally, one wants a functional form that captures reality adequately, yet is analytically sufficiently tractable to yield useful results. This paper gives two plausible risk aversion axioms that a reduced form utility function of temperature change and the capacity to produce consumption might reasonably be required to satisfy. These axioms indicate that the standard-practice multiplicative specification of disutility damages from global warming, as well as its additive analogue, are special cases of this paper's theoretically derived utility function. Empirically, the paper gives some numerical examples demonstrating the surprisingly strong implications for economic policy of the distinction between additive and multiplicative disutility damages.
A New Reagent for Direct Difluoromethylation

Molecular scaffolds containing alkylfluorine substituents are desired in many areas of chemical research from materials to pharmaceuticals. Herein, we report the invention of a new reagent (Zn(SO2CF2H)2, DFMS) for the innate difluoromethylation of organic substrates via a radical process. This mild, operationally simple, chemoselective, and scalable difluoromethylation method is compatible with a range of nitrogen-containing heteroarene substrates of varying complexity as well as select classes of conjugated π-systems and thiols. Regiochemical comparisons suggest that the CF2H radical generated from the new reagent possesses nucleophilic character.
Moving defects in AdS/CFT

We study defects of various dimensions moving through Anti-de Sitter space. Using the AdS/CFT correspondence this allows us to probe aspects of the dual quantum field theory. We focus on the energy loss experienced by these defects as they move through the CFT plasma. We find that the behavior of these physical quantities is governed by induced world-volume horizons. We identify world-volume analogs for several gravitational phenomena including black holes, the Hawking-Page phase transition and expanding cosmological horizons.
3-amino-2,3-dideoxy-D-erythro-furanose derivatives

Abstract D-xylose has been converted into methyl 3-nitro-2,3-dideoxy-D- erythro -furanoside and several analogs which are modified at the 5-position (5-O-benzoyl, 5-O-trimethylacetyl, the uronic acid and methyl uronate ester). These nitro sugars were conveniently hydrogenated to the corresponding amino sugars 1A–1E. The utility of the trimethylacetyl protecting group has been demonstrated for this sequence of reactions.