cssi/SciSciGPT-SciSciNet huggingface dataset:
Modeling Molecular Hydrogen and Star Formation in Cosmological Simulations

We describe a phenomenological model for molecular hydrogen formation suited for applications in galaxy formation simulations, which includes nonequilibrium formation of H{sub 2} on dust and approximate treatment of both its self-shielding and shielding by dust from the dissociating UV radiation. The model is applicable in simulations in which individual star-forming regions-the giant molecular complexes-can be identified (resolution of tens of parsecs) and their mean internal density estimated reliably, even if internal structure is not resolved. In agreement with previous studies, calculations based on our model show that the transition from atomic to fully molecular phase depends primarily on the metallicity, which we assume is directly related to the dust abundance, and clumpiness of the interstellar medium. The clumpiness simply boosts the formation rate of molecular hydrogen, while dust serves both as a catalyst of H{sub 2} formation and as an additional shielding from dissociating UV radiation. The upshot is that it is difficult to form fully shielded giant molecular clouds while gas metallicity is low. However, once the gas is enriched to Z {approx} 0.01-0.1 Z {sub sun}, the subsequent star formation and enrichment can proceed at a much faster rate. This may keep star formation efficiency in themore » low-mass, low-metallicity progenitors of galaxies very low for a certain period of time with the effect similar to a strong 'feedback' mechanism. The effect may help explain the steep increase of the mass-to-light ratio toward smaller masses observed in the local galaxy population. We apply the model and star formation recipes based on the local amount of molecular gas to an output from a cosmological simulation of galaxy formation and show that resulting global correlations between star formation and gas, and H{sub 2} surface densities are in good agreement with observations.« less
Mild Two-Step Process for the Transition-Metal-Free Synthesis of Carbon−Carbon Bonds from Allylic Alcohols/Ethers and Grignard Reagents

A mild two-step process for the regioselective, transition-metal-free preparation of carbon−carbon bonds from allylic alcohols/ethers and Grignard reagents is described. This process obviates the need for the harsh deprotection conditions usually required for removal of methyl ethers. The synthesis is accomplished by photochemically promoted allylic substitution reactions of allylic alcohols and ethers with diethylphosphorothioic acid followed by sp3−sp3 or sp2−sp3 bond formation with various Grignard reagents under transition-metal-free conditions. Depending on the nature of the nucleophile, the regioselectivity of the carbon−carbon bond-forming event can be controlled to furnish either quaternary or tertiary carbon centers.
Movement of implicit parallel and vector expressions out of program loops

The concept of “interference” is introduced and related to the problem of transforming implicit parallel and vector operations to an explicit form. Statement types and constructs which cause interference are identified. Programming techniques which avoid use of potentially interfering statements result in programs which are better suited for operation on parallel and vector processors.The analysis of the inhibiting effect of interfering statements on the motion of parallel and vector expressions has been implemented and demonstrated as an addition to an existing compiler which recognizes parallelism implicit in current serial programs.
THE PRICE LEVEL, THE QUANTITY THEORY OF MONEY, AND THE FISCAL THEORY OF THE PRICE LEVEL

This paper examines price-level determination from the perspective of portfolio choice. Arbitrages among money balances, bonds, and investment goods determine their relative demands. Returns to real balance holdings and after-tax returns to investment goods determine the relative values of nominal and real assets. Because expectations of government policies ultimately determine the expected returns to both nominal and real assets, the price level depends on interactions among current and expected future monetary and fiscal policies. The quantity theory and the fiscal theory emerge as special cases produced by restricting both the margins and the policies considered.
Minimizing mean flow time with release time and deadline constraints

Abstract The problem of preemptively scheduling a set of n independent tasks on a single processor so as to minimize the mean flow time is considered. Each task has associated with it a processing time, a release time, and a deadline. A feasible schedule is one in which each task is completely processed within its interval of release time and deadline. The problem is to find a feasible schedule with the minimum mean flow time. It is known that two special cases of the problem can be solved in O ( n log n ) time: the case of identical deadlines by the smallest remaining processing time rule as described by Baker and the case of identical release times by the deadline rule as described by Smith. In this paper we generalize both algorithms and show that they solve a much broader class of problem instances, namely those which contain no triple of tasks satisfying certain conditions. The generalized algorithms, and an algorithm that recognizes problem instances satisfying the condition, can all be implemented in O ( n 2 ) time. Finally, we show that the general problem is NP-hard, answering an open question posed by Lawler.
Development of Zn–ProPhenol‐Catalyzed Asymmetric Alkyne Addition: Synthesis of Chiral Propargylic Alcohols

The development of a general and practical zinc-catalyzed enantioselective alkyne addition methodology is reported. The commercially available ProPhenol ligand (1) has facilitated the addition of a wide range of zinc alkynylides to aryl, aliphatic, and α,β-unsaturated aldehydes in high yield and enantioselectivity. New insights into the mechanism of this reaction have resulted in a significant reduction in reagent stoichiometry, enabling the use of precious alkynes and avoiding the use of excess dimethylzinc. The enantioenriched propargylic alcohols from this reaction serve as versatile synthetic intermediates and have enabled efficient syntheses of several complex natural products.
Using meta-analysis for benefits transfer: Theory and practice

Abstract Meta-analysis, or the “study of studies”, attempts to statistically measure systematic relationships between reported valuation estimates for an environmental good or service and attributes of the study that generated the estimates including valuation methods, human population and sample characteristics, and characteristics of the good or service itself. In this paper, we discuss the general theory behind and practice of the emerging use of meta-analysis for benefits transfer. We believe that meta-analysis may prove to be a useful tool for benefits transfer in particular applications if it is carefully conducted following systematic protocols for model development, data collection, and data analysis and interpretation. However, before widespread application of this method, more convergent validity tests are needed. One of the greatest strengths of using meta-analysis for benefits transfer is the ability to combine and summarize large amounts of information from previous studies. This strength can also lead to one of the greatest weaknesses of this method which is the loss of important valuation details across time and space in the aggregation process.
Effective Diffusivity in Baroclinic Flow

Large-scale chaotic stirring stretchestracer contoursintofilamentscontainingfine spatial scales until smallscale diffusive processes dissipate tracer variance. Quantification of tracer transport in such circumstances is possible through the use of Nakamura’s ‘‘effective diffusivity’’ diagnostics, which make clear the controlling role of stirring, rather than small-scale dissipation, in large-scale transport. Existing theory of effective diffusivity is based on a layerwise approach, in which tracer variance is presumed to cascade via horizontal (or isentropic) stirring to small-scale horizontal (or isentropic) diffusion. In most geophysical flows of interest, however, baroclinic shear will tilt stirred filamentary structures into almost-horizontal sheets, in which case the thinnest dimension is vertical; accordingly, it will be vertical (or diabatic) diffusion that provides the ultimate dissipation of variance. Here new theoretical developments define effective diffusivity in such flows. In the frequently relevant case of isentropic stirring, it is shown that the theory is, in most respects, unchanged from the case ofisentropic diffusion:effectiveisentropic diffusivity is controlledby the isentropicstirring and, itisargued,largelyindependentofthenatureoftheultimatedissipation.Diabaticdiffusionisnotamplifiedby the stirring, although it can be modestly enhanced through eddy modulation of static stability. These characteristics are illustrated in numerical simulations of a stratospheric flow; in regions of strong stirring, the theoretical predictions are well supported, but agreement is less good where stirring is weaker.
Exotic differentiable structures and general relativity

We review recent developments in differential topology with special concern for their possible significance to physical theories, especially general relativity. In particular we are concerned here with the discovery of the existence of non-standard (“fake” or “exotic”) differentiable structures on topologically simple manifolds such asS 7, ℝ4 andS 3 X ℝ1. Because of the technical difficulties involved in the smooth case, we begin with an easily understood toy example looking at the role which the choice of complex structures plays in the formulation of two-dimensional vacuum electrostatics. We then briefly review the mathematical formalisms involved with differentiable structures on topological manifolds, diffeomorphisms and their significance for physics. We summarize the important work of Milnor, Freedman, Donaldson, and others in developing exotic differentiable structures on well known topological manifolds. Finally, we discuss some of the geometric implications of these results and propose some conjectures on possible physical implications of these new manifolds which have never before been considered as physical models.
Configuration-Space-Faddeev Born Approximations

Alternative definitions of the Born approximation and the distorted-wave Born approximation within the framework of the configuration-space Faddeev equations are explored. The most natural definition does not correspond to the Born approximation derived from the Schrodinger equation, even though the exact T-matrices for both formalisms are equivalent. The Schrodinger form is optimal, although it is shown that the differences are numerically unimportant. The DWBA corresponding to the Faddeev equations is not channel symmetric, although numerically this is unimportant for the p-d (Coulomb) case. The place in the partial-wave series beyond which the Born approximation can be effectively substituted for the exact result is briefly investigated for p-d and n-d scattering below breakup threshold.
The fragmentation of benzyloxychlorocarbene: Formation of benzyl cation

Abstract Thermolysis of 3-benzyloxy-3-chlorodiazirine in MeCN at 25°C affords benzyloxychlorocarbene that fragments cleanly to the benzyl cation.
Strong singularity for subfactors

We examine the notion of $\alpha$-strong singularity for subfactors of a \IIi factor, which is a metric quantity that relates the distance between a unitary in the factor and a subalgebra with the distance between that subalgebra and its unitary conjugate. Through planar algebra techniques, we demonstrate the existence of a finite index singular subfactor of the hyperfinite \IIi factor that cannot be strongly singular with $\alpha=1$, in contrast to the case for masas. Using work of Popa, Sinclair, and Smith, we show that there exists an absolute constant $0<c<1$ such that all singular subfactors are $c$-strongly singular. Under the hypothesis of 2-transitivity, we prove that finite index subfactors are $\alpha$-strongly singular with a constant that tends to 1 as the Jones Index tends to infinity and infinite index subfactors are 1-strongly singular. Finally, we give a proof that proper finite index singular subfactors do not have the weak asymptotic homomorphism property relative to the containing factor.
To use or not to use cool superconductors

The high critical temperature and magnetic field in cuprates and Fe-based superconductors are not enough to assure applications at higher temperatures. Making these superconductors useful involves complex and expensive technologies to address many conflicting physics and materials requirements.
Remarkable regularity in the lepton-pair widths of vector mesons

Abstract Regularity apparent in the lepton-pair widths of the vector mesons, ϱ, ω, θ, J/ψ and Y , is discussed with emphasis on the historical development of the subject.
Helicity, topology, and force-free fields

Concepts from topology are increasingly finding utility in magnetohydrodynamics. This paper gives an example of how the connectivity of the domain and the gauge freedom of the vector potential can play an important role in computing the helicity of twisted magnetic fields used in several areas of astrophysics, particularly solar physics. By computing the relative helicity of a simple magnetic field configuration used to model solar prominences, it is shown that helicity can have a nonlocal character. This necessitates a reexamination of its conventional physical interpretation. The magnetic energy is also discussed.
Arbitrage-free Self-organizing Markets with GARCH Properties: Generating them in the Lab with a Lattice Model

Abstract We extend our studies of a quantum field model defined on a lattice having the dilation group as a local gauge symmetry. The model is relevant in the cross-disciplinary area of econophysics. A corresponding proposal by Ilinski aimed at gauge modeling in non-equilibrium pricing is realized as a numerical simulation of the one-asset version. The gauge field background enforces minimal arbitrage, yet allows for statistical fluctuations. The new feature added to the model is an updating prescription for the simulation that drives the model market into a self-organized critical state. Taking advantage of some flexibility of the updating prescription, stylized features and dynamical behaviors of real-world markets are reproduced in some detail.
Probing T Tauri Accretion and Outflow with 1 Micron Spectroscopy

In a high-dispersion 1 μm survey of 39 classical T Tauri stars (CTTSs) veiling is detected in 80% of the stars, and He I λ10830 and Pγ line emission in 97%. On average, the 1 μm veiling exceeds the level expected from previously identified sources of excess emission, suggesting the presence of an additional contributor to accretion luminosity in the star-disk interface region. Strengths of both lines correlate with veiling, and at Pγ there is a systematic progression in profile morphology with veiling. He I λ10830 has an unprecedented sensitivity to inner winds, showing blueshifted absorption below the continuum in 71% of the CTTSs, compared to 0% at Pγ. This line is also sensitive to magnetospheric accretion flows, with redshifted absorption below the continuum found in 47% of the CTTSs, compared to 24% at Pγ. The blueshifted absorption at He I λ10830 shows considerable diversity in its breadth and penetration depth into the continuum, indicating that a range of inner wind conditions exist in accreting stars. We interpret the broadest and deepest blue absorptions as formed from scattering of the 1 μm continuum by outflowing gas whose full acceleration region envelopes the star, suggesting radial outflow from the star. In contrast, narrow blue absorption with a range of radial velocities more likely arises via scattering of the 1 μm continuum by a wind emerging from the inner disk. Both stellar and disk winds are accretion powered, since neither is seen in nonaccreting WTTSs and among the CTTSs helium strength correlates with veiling.
An efficient synthesis of (±)-crinane using an intramolecular azide-olefin cycloaddition

Abstract Refluxing 3-(2-azidoethyl)-3-[3,4-(methylenedioxy)phenyl]cyclohex-1-ene ( 2 ) in toluene for 24 hours afforded 3a-[3,4-methylenedioxy)phenyl]-3,3a,4,5,6,7-hexahydro-2 H -indole ( 12 ) in quantitative yield. This reaction proceeds by intramolecular 1,3-dipolar cycloaddition of the azide onto the alkene followed by loss of nitrogen from the triazoline intermediate to give an imine. Reduction of the imine 12 with sodium cyanoborohydride in acetic acid/THF gave (3aR ∗ , 7aR ∗ )-3a-[3,4-methylenedioxy)phenyl]-2,3,3a,4,5,6,7,7a-octahydroindole ( 13 ). Warming 13 with Eschenmoser's salt provided (±)-crinane ( 1 ). The synthesis of (±)-crinane ( 1 ) from cyclohexenone was accomplished in 8 steps in 23% overall yield.
Identifying meteorite source regions through near-Earth object spectroscopy

Abstract By virtue of their landing on Earth, meteorites reside in near-Earth object (NEO) orbits prior to their arrival. Thus the population of observable NEOs, in principle, gives important representation of meteorite source bodies. By linking meteorites to NEOs, and linking NEOs to their most likely main-belt source locations, we seek to gain insight into the original Solar System formation locations for different meteorite classes. To forge possible links between meteorites and NEOs, we have developed a three dimensional method for quantitative comparisons between laboratory measurements of meteorites and telescopic measurements of near-Earth objects. We utilize meteorite spectra from the Reflectance Experiment Laboratory (RELAB) database and NEO data from the SpeX instrument on the NASA Infrared Telescope Facility (IRTF). Using the Modified Gaussian Model (MGM) as a mathematical tool, we treat asteroid and meteorite spectra identically in the calculation of 1-μm and 2-μm Geometric Band Centers and their Band Area Ratios (BARs). Using these identical numerical parameters we quantitatively compare the spectral properties of S-, Sq-, Q- and V-type NEOs with the spectral properties of the meteorites in four classes: H, L, LL and HED. For each NEO spectrum, we assign a set of probabilities for it being related to each of these four meteorite classes. Our NEO-meteorite correlation probabilities are then convolved with NEO-source region probabilities to yield a final set of meteorite-source region correlations. While the ν6 resonance dominates the delivery for all four meteorite classes, an excess (significant at the 2.1-sigma level) source region signature is found for the H chondrites through the 3:1 mean motion resonance. This results suggest an H chondrite source with a higher than average delivery preference through the 3:1 resonance. A 3:1 resonance H chondrite source region is consistent with the short cosmic ray exposure ages known for H chondrites.
On the Absence of Ferromagnetism in Typical 2D Ferromagnets

We consider the Ising systems in d dimensions with nearest-neighbor ferromagnetic interactions and long-range repulsive (antiferromagnetic) interactions that decay with power s of the distance. The physical context of such models is discussed; primarily this is d = 2 and s = 3 where, at long distances, genuine magnetic interactions between genuine magnetic dipoles are of this form. We prove that when the power of decay lies above d and does not exceed d + 1, then for all temperatures the spontaneous magnetization is zero. In contrast, we also show that for powers exceeding d + 1 (with d ≥ 2) magnetic order can occur.
Studies on the total synthesis of lactacystin. An improved aldol coupling reaction and a β-lactone intermediate in thiol ester formation

Abstract The recently developed total synthesis of lactacystin (1) has been improved by using the zirconium enolate derived from (R)- or (S)-2-siloxy-1,2,2-triphenylpropionate which lead stereospecifically to either (6S, 7R) or (6R, 7S) lactacystin, respectively. The formation of the thiol ester in the synthesis of 1 proceeds mainly via a β-lactone intermediate.
In-situ preparation of radioactive tracers in NIF capsules

Summary form only given. Inertial Confinement Fusion (ICF) experiments at the National Ignition Facility (NIF) will probe fundamental high energy density physics of plasmas. Radiochemical diagnostics will provide information on ablator and fuel rho-R, yield, asymmetry, and mix by collecting both gaseous and solid debris samples following an implosion. Many experiments utilize ratios of produced activities, but full utilization of the technique requires knowledge of sample collection efficiencies. Gaseous samples are expected to be collected with high efficiency, but solid sample collection is typically limited by location of the collecting apparatus. Activation of ICF capsules has been utilized at other laser facilities to produce a radioactive tracer in the ablator of the capsule that can be used to measure the solid collection efficiency. This talk will describe preliminary experiments activating CH(Ge) NIF capsules and Au hohlraums in the High Flux Isotope Reactor (HFIR) at ORNL in order to produce Ge, As, and Au isotopes for determination of collection efficiency, spatial distribution of the debris, efficacy of various collectors, and if there are preferred locations for debris collection.
A Test of the AdS/CFT Duality on the Coulomb Branch

Abstract We consider the N =4 SU(N) Super Yang Mills theory on the Coulomb branch with gauge symmetry broken to S(U(N1)×U(N2)). By integrating the W particles, the effective action near the IR SU(Ni) conformal fixed points is seen to be a deformation of the Super Yang Mills theory by a non-renormalized, irrelevant, dimension 8 operator. The correction to the two-point function of the dilaton field dual operator near the IR is related to a three-point function of chiral primary operators at the conformal fixed points and agrees with the classical gravity prediction, including the numerical factor.
Next Generation 400 Gb/s Transmission

Different strategies for enabling beyond 400 Gb/s serial optical transport will be described in this invited paper: (i) single-carrier multidimensional coded-modulation, (ii) optimum signal constellations based optical transmission, and (iii) multi-band coded-OFDM.
Aerodynamic interaction between propellers and wings

A combined computational/experimental investigation has been conducted to determine the time-averaged interactive performance of a propeller and wing in tractor configuration at Mach 0.1 and Re=470,000, based on a wind tunnel model wing chord of 8 in. Wing angle-of-attack was varied from 0 to +13 deg, and propeller advance ratio ranged from 2.4 (windmilling) to 1.1 (maximum power). Both a semiempirical model and a vortex lattice simulation were used in the computational analysis. Good agreement has been obtained between theory and experiment.
The role of the delocalized α,α′-carbanion in vitamin B6 and Al(III) catalyzed transamination of α-amino and α-keto acids

Abstract The rates of the transamination reactions of α-amino acids and α-keto acids were followed by measurement of the 200 MHz proton NMR spectra of solution species as a function of time. Reaction systems measured in D 2 O at 10 °C consisted of 1:1:1 molar ratios of pyridoxal:α-amino acid:Al(III) or pyridoxamine:α-keto acid:Al(III). Amino and keto acids employed are alanine, α-aminoisobutyric acid, valine, phenylglycine, pyruvic acid, and α-ketobutyric acid. A negatively charged deprotonated Schiff base coordinated to Al(III) was detected in all systems that undergo transamination ( i.e. , except α-aminoisobutyric acid). The intermediate resembles the aldimine Al(III) chelate with NMR resonances shifted upfield in accordance with its greater negative charge. Its equilibrium concentration is reached in the time required to reach transamination equilibrium and is maintained in solution at a ca . 10–20% of the aldimine Schiff base concentration.
Common-path heterodyne laser-induced thermal acoustics for seedless laser velocimetry

We demonstrate the use of a novel technique for the detection of heterodyne laser-induced thermal acoustic signals that allows the construction of a highly stable seedless laser velocimeter. A common-path configuration is combined with quadrature detection to provide flow direction, to greatly improve robustness to misalignment and vibration, and to give reliable velocity measurement at low-flow velocities. Comparison with Pitot tube measurements in the free stream of a wind tunnel shows root-mean-square errors of 0.67 m/s over the 0-55-m/s velocity range.
Risk Sharing and Group Decision Making

In a decision-making problem where a group will receive an uncertain payoff which must be divided among the members of the group, the ultimate payoff of interest is the vector of individual payoffs received by the members of the group. In this paper, preferences are quantified in terms of cardinal utility functions for such vectors of payoffs. These utility functions can represent preferences concerning "equitable" and "inequitable" vectors of payoffs as well as attitudes toward risk. The individual utility functions are aggregated to form a group utility function for the vector of payoffs, and this latter function is, in turn, used to generate a group utility function for the overall group payoff and a sharing rule for dividing the group payoff into individual payoffs. The resulting group decisions are Pareto optimal in utility space. Properties of the sharing rule and the group utility function are investigated for additive and multilinear group utility functions.
International Farm Prices and the Social Cost of Cheap Food Policies

The evidence suggests that real prices received by farmers in the less-developed countries (LDCs) have been substantially lower than farm prices in the developed nations. Estimates of a long-run aggregate agricultural supply elasticity from cross-section data reveal that it is relatively elastic, in the range of 1.25 to 1.66. It is estimated also that, with more-favorable farm prices, agricultural output in a group of twenty-seven LDCs could have been 40% to 60% greater than it was and the national income of the group increased by more than 3% annually. 13 references.
Social Cognition and Health

Health settings provide an important arena within which to test and refine social psychological theories. Using interview data from cancer patients, results are presented pertaining to four areas of social psychological theory: attribution theory, psychological control, social comparison theory, and victimization.
The presence of telomere fusion in sporadic colon cancer independently of disease stage, TP53/KRAS mutation status, mean telomere length, and telomerase activity.

Abstract Defects in telomere maintenance can result in telomere fusions that likely play a causative role in carcinogenesis by promoting genomic instability. However, this proposition remains to be fully understood in human colon carcinogenesis. In the present study, the temporal sequence of telomere dysfunction dynamics was delineated by analyzing telomere fusion, telomere length, telomerase activity, hotspot mutations in KRAS or BRAF , and TP53 of tissue samples obtained from 18 colon cancer patients. Our results revealed that both the deficiency of p53 and the shortening of mean telomere length were not necessary for producing telomere fusions in colon tissue. In five cases, telomere fusion was observed even in tissue adjacent to cancerous lesions, suggesting that genomic instability is initiated in pathologically non-cancerous lesions. The extent of mean telomere attrition increased with lymph node invasiveness of tumors, implying that mean telomere shortening correlates with colon cancer progression. Telomerase activity was relatively higher in most cancer tissues containing mutation(s) in KRAS or BRAF and/or TP53 compared to those without these hotspot mutations, suggesting that telomerase could become fully active at the late stage of colon cancer development. Interestingly, the majority of telomere fusion junctions in colon cancer appeared to be a chromatid-type containing chromosome 7q or 12q. In sum, this meticulous correlative study not only highlights the concept that telomere fusion is present in the early stages of cancer regardless of TP53/KRAS mutation status, mean telomere length, and telomerase activity, but also provides additional insights targeting key telomere fusion junctions which may have significant implications for colon cancer diagnoses.
Resolved shock structure of the Balmer-dominated filaments in Tycho's supernova remnant: Cosmic-ray precursor?

We report on the results from Hα imaging observations of the eastern limb of Tycho's supernova remnant (SN1572) using the Wide Field Planetary Camera 2 on the Hubble Space Telescope. We resolve the detailed structure of the fast, collisionless shock wave into a delicate structure of nearly edge-on filaments. We find a gradual increase of Hα intensity just ahead of the shock front, which we interpret as emission from the thin (~1'') shock precursor. We find that a significant amount of the Hα emission comes from the precursor and that this could affect the amount of temperature equilibration derived from the observed flux ratio of the broad and narrow Hα components. The observed Hα emission profiles are fit using simple precursor models, and we discuss the relevant parameters. We suggest that the precursor is likely due to cosmic rays and discuss the efficiency of cosmic-ray acceleration at this position.
Stellar Rotation in Young Clusters. I. Evolution of Projected Rotational Velocity Distributions

Open clusters offer us the means to study stellar properties in samples with well-defined ages and initial chemical composition. Here we present a survey of projected rotational velocities for a large sample of mainly B-type stars in young clusters to study the time evolution of the rotational properties of massive stars. The survey is based on moderate-resolution spectra made with the WIYN 3.5 m and CTIO 4 m telescopes and Hydra multi-object spectrographs, and the target stars are members of 19 young open clusters with an age range of approximately 6-73 Myr. We made fits of the observed lines He I λλ4026, 4387, 4471, and Mg II λ4481, using model theoretical profiles to find projected rotational velocities for a total of 496 OB stars. We find that there are fewer slow rotators among the cluster B-type stars relative to nearby B stars in the field. We present evidence consistent with the idea that the more massive B stars (M > 9 M☉) spin down during their main-sequence phase. However, we also find that the rotational velocity distribution appears to show an increase in the numbers of rapid rotators among clusters with ages of 10 Myr and higher. These rapid rotators appear to be distributed between the zero age and terminal age main-sequence locations in the Hertzsprung-Russell diagram, and thus only a minority of them can be explained as the result of a spin-up at the terminal age main sequence due to core contraction. We suggest instead that some of these rapid rotators may have been spun up through mass transfer in close binary systems.
Synchronization of globally coupled phase oscillators: singularities and scaling for general couplings

Abstract The onset of collective behavior in a population of globally coupled oscillators with randomly distributed frequencies is studied for phase dynamical models with arbitrary coupling; the effect of a stochastic temporal variation in the frequencies is also included. The Fokker-Planck equation for the coupled Langevin system is reduced to a kinetic equation for the oscillator distribution function. Instabilities of the phase-incoherent state are studied by center manifold reduction to the amplitude dynamics of the unstable modes. Depending on the coupling, the coefficients in the normal form can be singular in the limit of weak instability when the diffusive effect of the noise is neglected. A detailed analysis of these singularities to all orders in the normal form expansion is presented. Physically, the singularities are interpreted as predicting an altered scaling of the entrained component near the onset of synchronization. These predictions are verified by numerically solving the kinetic equation for various couplings and frequency distributions.
Efficient submesh permutations in wormhole-routed meshes

Abstract This paper studies how to concurrently permute related logical or physical submeshes in a d -dimensional n × … × n physical mesh via wormhole and dimension-ordered routing. Our objective is to minimize the congestion for realizing the permutations, while maximizing the number and dimensionality of permuted submeshes. We show that for d ⩽ 2 α + β , concurrent independent permutations of n β related physical submeshes, each of α dimensions, can be performed in two routing steps without congestion. If the permuted submeshes are logical ones, they can be permuted in one, instead of two, routing step. In addition, any shift operation along any axis of the logical mesh can be performed in the physical mesh without congestion. We also show that if all nodes know the permutation function, any permutation within a submesh of dimensions ⌊2( d − 1)/3⌋ can be realized in three routing steps without congestion.
Cramer-Rao bounds for long-wave infrared gaseous plume quantification

The central parameter in the quantification of chemical vapor plumes via remote sensing is the mean concentration-path length (CL) product, which can be combined with scene geometry information to provide estimates of the absolute gas quantity present. We derive Cramer-Rao lower bounds on the variance of an unbiased estimator of CL in concert with other parameters of a nonlinear radiance model. These bounds offer a guide to feasibility of CL estimation that is not dependent on any given algorithm. In addition, the derivation of the bounds yields great insight into the physical and phenomenological mechanisms that control plume quantification, which we illustrate with examples representing a variety of experimental scenarios.
The Orbital Period of the Ultracompact Low-Mass X-Ray Binary 4U 1543–624

We report the discovery of the orbital period of the ultracompact low-mass X-ray binary (LMXB) 4U 1543-624 using time-resolved optical photometry taken with the 6.5 m Clay (Magellan II) telescope in Chile. The light curve in the Sloan r' band clearly shows a periodic sinusoidal modulation at 18.2 ± 0.1 minutes with a fractional semiamplitude of 8%, which we identify as the binary period. This is the second shortest orbital period among all the known LMXBs, and it verifies the earlier suggestion of 4U 1543-624 as an ultracompact binary based on X-ray spectroscopic properties. The sinusoidal shape of the optical modulation suggests that it arises from X-ray heating of the mass donor in a relatively low-inclination binary, although it could also be a superhump oscillation, in which case the orbital period is slightly shorter. If the donor is a C-O white dwarf as previously suggested, its likely mass and radius are around 0.03 M☉ and 0.03 R☉, respectively. For conservative mass transfer onto a 1.4 M☉ neutron star and driven by gravitational radiation, this implies an X-ray luminosity of 6.5 × 1036 ergs s-1 and a source distance of ≈7 kpc. We also discuss optical photometry of another LMXB, the candidate ultracompact binary 4U 1822-000. We detected significant optical variability on a timescale of about 90 minutes, but it is not yet clear whether this was due to a periodic modulation.
Resonant Excitation of Disk Oscillations in Deformed Disks III: Revision of Mathematical Treatment

In previous studies, we have examined a resonant excitation of disk oscillations in deformed disks. In these studies, however, the mathematical treatment around the resonant points was not rigorous. In this paper the inadequate point is corrected, but with no essential changes in the final results. For this excitation process to work, disks must be general relativistic. That is, a non-monotonic radial distribution of the epicyclic frequency in relativistic disks is essential for the presence of the resonance, and for trapping oscillations. In this paper, the growth rate of resonant oscillations is expressed in a form more suitable for numerical calculations.
Active noise control for periodic disturbances

Proposes an active noise control algorithm for periodic disturbances of unknown frequency. The algorithm is appropriate for the feedback case in which a single error microphone is used. A previously proposed algorithm for the rejection of sinusoidal noise sources is extended for the cancellation of multiple harmonics. Unlike many other approaches, the estimates of the frequencies of the separate harmonics are tied together within the algorithm to account for the integer multiplicative relations between them. The dynamic behavior of the closed-loop system is analyzed using an approximation that is shown, in simulations, to provide an accurate representation of the system's behavior. Experimental results on an active noise control testbed demonstrate the success of the method in a practical environment.
History’s Challenge to Criminal Law Theory

After briefly sketching an historical account of criminal law that emphasizes its longstanding reach into social, commercial and personal life outside the core areas of criminal offenses, this paper explores why criminal law theory has never succeeded in limiting the content of criminal codes to offenses that fit the criteria of dominant theories, particularly versions of the harm principle. Early American writers on criminal law endorsed no such limiting principles to criminal law, and early American criminal law consequently was substantively broad. But even with the rise of theories in the mid-nineteenth century that sought to limit criminal law’s reach, codified offenses continued to widely and deeply regulate social life and exceed the limits of those normative arguments. This essay suggests that this practical failure of criminal law theory occurred because it was never adopted by an institutional actor that could limit offense definitions in accord with normative commitments. Legislatures are institutionally unsuited to having their policy actions limited by principled arguments, and courts passed on the opportunity to incorporate a limiting principle for criminal law once they began, in the Lochner era, actively regulating legislative decisions through Constitutional law. The one avenue through which criminal law theory has had some success in affecting criminal codes is through the influence of specialized bodies that influence legislation, especially the American Law Institute advocacy of the Model Penal Code. But the institutional structure of American criminal law policymaking permits an unusually small role for such specialized bodies, and without such an institutional mechanism, criminal law theory is likely to continue to have little effect on actual criminal codes.
Analyzing Cosmic Bubble Collisions

We develop a set of controlled, analytic approximations to study the effects of bubble collisions on cosmology. We expand the initial perturbation to the inflaton field caused by the collision in a general power series, and determine its time evolution during inflation in terms of the coefficients in the expansion. In models where the observer's bubble undergoes sufficient slow-roll inflation to solve the flatness problem, in the thin wall limit only one coefficient in the expansion is relevant to observational cosmology, allowing nearly model-independent predictions. We discuss two approaches to determining the initial perturbation to the inflaton and the implications for the sign of the effect (a hot or cold spot on the Cosmic Microwave Background temperature map). Lastly, we analyze the effects of collisions with thick-wall bubbles, i.e. away from the thin-wall limit.
The Unusual Spectrum of Comet 96P/Machholz

We report spectra from 3000 to 5900 A for comet 96P/Machholz, obtained on 2007 April 27 UT with the 3 m Shane telescope at Lick Observatory. The spectra are extremely carbon-poor, and they show a prominent NH2 series but no CN emission. NH, NH2, and C2 gas production rates are (8.36 ± 2.18) × 1025, (29.88 ± 3.66) × 1025, and (4.52 ± 0.61) × 1023 molecules s-1, respectively, as determined from Haser model fits to the data. Upper limits to the gas production rates for CN and C3 are 7.5 × 1022 and 2.0 × 1023, respectively. Although 96P is depleted in C2 and C3 relative to NH, it is even more depleted in CN than other so-called carbon chain-depleted comets.
The euro crisis: Where to from here?

union. One possible view is that the inherent difﬁculties were so great that the euro wasdoomed to fail . But even if one takes the historic fact of European monetary union as given, aconsideration of how it could have been pursued differently should precede a discussion of ideasfor how to ﬁx the ﬂaws that have become evident in the crisis.
The space of embedded minimal surfaces of fixed genus in a 3-manifold IV; Locally simply connected

This paper is the fourth in a series where we describe the space of all embedded minimal surfaces of fixed genus in a fixed (but arbitrary) closed 3manifold. The key is to understand the structure of an embedded minimal disk in a ball in R3. This was undertaken in [CM3], [CM4] and the global version of it will be completed here; see the discussion around Figure 12 for the local case and [CM15] for some more details. Our main results are Theorem 0.1 (the lamination theorem) and Theorem 0.2 (the one-sided curvature estimate). The lamination theorem is stated in the global case where the lamination is, in fact, a foliation. The first four papers of this series show that every embedded minimal disk is either a graph of a function or is a double spiral staircase where each staircase is a multivalued graph. This is done by showing that if the curvature is large at some point (and hence the surface is not a graph), then it is a double spiral staircase like the helicoid. To prove that such a disk is a double spiral staircase, we showed in the first three papers of the series that it is built out of N-valued graphs where N is a fixed number. In this paper we will deal with how the multi-valued graphs fit together and, in particular, prove regularity of the set of points of large curvature - the axis of the double spiral staircase. The first theorem is the global version of the statement that every embedded minimal disk is a double spiral staircase.
WESD--Weighted Spectral Distance for Measuring Shape Dissimilarity

This paper presents a new distance for measuring shape dissimilarity between objects. Recent publications introduced the use of eigenvalues of the Laplace operator as compact shape descriptors. Here, we revisit the eigenvalues to define a proper distance, called Weighted Spectral Distance (WESD), for quantifying shape dissimilarity. The definition of WESD is derived through analyzing the heat trace. This analysis provides the proposed distance with an intuitive meaning and mathematically links it to the intrinsic geometry of objects. We analyze the resulting distance definition, present and prove its important theoretical properties. Some of these properties include: 1) WESD is defined over the entire sequence of eigenvalues yet it is guaranteed to converge, 2) it is a pseudometric, 3) it is accurately approximated with a finite number of eigenvalues, and 4) it can be mapped to the ([0,1)) interval. Last, experiments conducted on synthetic and real objects are presented. These experiments highlight the practical benefits of WESD for applications in vision and medical image analysis.
Robustness of Nonlinear Systems Perturbed by External Random Excitation

The effect of external random excitation on non linear continuous time systems is examined using the concept of the Lyapunov exponent. The Lyapunov exponent may be regarded as the non linear/!stochastic analog of the poles of a linear determininistic system
How to couple from the past using a read-once source of randomness

We give a new method for generating perfectly random samples from the stationary distribution of a Markov chain. The method is related to coupling from the past (CFTP), but only runs the Markov chain forwards in time, and never restarts it at previous times in the past. The method is also related to an idea known as PASTA (Poisson arrivals see time averages) in the operations research literature. Because the new algorithm can be run using a read-once stream of randomness, we call it read-once CFTP. The memory and time requirements of read-once CFTP are on par with the requirements of the usual form of CFTP, and for a variety of applications the requirements may be noticeably less. Some perfect sampling algorithms for point processes are based on an extension of CFTP known as coupling into and from the past; for completeness, we give a read-once version of coupling into and from the past, but it remains unpractical. For these point process applications, we give an alternative coupling method with which read-once CFTP may be efficiently used.
Hand dominance and performance in a laparoscopic skills curriculum

This study evaluated the influence of hand dominance on skill acquisition during a basic laparoscopic skills curriculum. A total of 27 surgical residents (5 postgraduate year 3 [PGY-3] and 22 PGY-2 residents) participated in a 4-week laparoscopic skills curriculum. The residents were pre- and posttested on six laparoscopic tasks during weeks 1 and 4. During weeks 2 and 3, the residents attended a proctored practice session. The results were compared using analysis of variance (ANOVA), (with significance determined by a p value less than 0.05. The posttest scores were significantly higher than the pretest scores. On the pretest, lefthand–dominant (LHD) surgeons (n = 4) performed significantly better than righthand–dominant (RHD) surgeons (n = 23). In the analysis of individual task pretest scores, LHD surgeons performed significantly better on pattern cutting and vessel loop application. Posttest analysis of overall performance did not show significant differences between the RHD and LHD surgeons. Participation in a laparoscopic skills curriculum improved overall performance. The LHD surgeons demonstrated better initial performance, but posttest comparison showed no difference between the two groups.
A comment on positive mass for scalar field sources

We use a transformation due to Bekenstein to relate the ADM and Bondi masses of asymptotically-flat solutions of the Einstein equations with, respectively, scalar sources and conformal-scalar sources. Although the conformal-scalar energy-momentum tensor does not satisfy the Dominant Energy Condition one may, by this means, still conclude that the ADM mass is positive.
Enantioselective intramolecular alkene hydroaminations catalyzed by yttrium complexes of axially chiral bis(thiolate) ligands.

A yttrium(III) complex derived from proligand 7c has been shown to be a superior catalyst for enantioselective intramolecular alkene hydroaminations that provide cyclic amines with ee's ranging from 69% to 89%.
THE GROWTH OF FINGERS AND BUBBLES IN THE STRONGLY NONLINEAR REGIME OF THE RICHTMYER-MESHKOV INSTABILITY

Abstract A variational method is proposed for the description of the free surface dynamics in the strongly nonlinear regime. In the simplest case, when there is a single symmetric finger, this method gives a simple integrable Hamiltonian system with two degrees of freedom (which are, roughly speaking, the height and the width of the finger). The general solution of this system is found, and physical implications are discussed.