cssi/SciSciGPT-SciSciNet huggingface dataset:
THREE PARTICLE CORRELATIONS FROM STAR

Two-particle correlations have shown modification to the away-side shape in central Au+Au collisions relative to pp, d+Au and peripheral Au+Au collisions. Different scenarios can explain this modification including: large angle gluon radiation, jets deflected by transverse flow, path length dependent energy loss, Cerenkov gluon radiation of fast moving particles, and conical flow generated by hydrodynamic Mach-cone shock-waves. Three-particle correlations have the power to distinguish the scenarios with conical emission, conical flow and Cerenkov radiation, from other scenarios. In addition, the dependence of the observed shapes on the pT of the associated particles can be used to distinguish conical emission from a sonic boom (Mach-cone) and from QCD-Cerenkov radiation. We present results from STAR on 3-particle azimuthal correlations for a high pT trigger particle with two softer particles. Results are shown for pp, d+Au and high statistics Au+Au collisions at . An important aspect of the analysis is the subtraction of combinatorial backgrounds. Systematic uncertainties due to this subtraction and the flow harmonics v2 and v4 are investigated in detail. The implications of the results for the presence or absence of conical flow from Mach-cones are discussed.
Observational evidence of African desert dust intensification of easterly waves

[1] This paper presents indirect observational evidence that desert dust can modulate the amplitude of easterly waves in the Atlantic Ocean. Twenty two years of NCEP/NCAR reanalysis and dust from a global transport model are used to characterize the evolution of enhanced easterly waves. Lag composites of analysis increments (analysis minus first–guess) of geopotential height (700–hPa) anomalies indicate larger amplitudes in the analysis than in the first-guess fields. The results indicate that the temperature structure in the lower troposphere associated with easterly waves is warmer in the analysis than in first–guess fields by about 0.25 K per day. We hypothesize that the differences in the amplitudes are due to radiative effects associated with African dust, which have been incorporated in the reanalysis by data assimilation but absent in the model first–guess.
Direct N-Carbamoylation of 3-Monosubstituted Oxindoles with Alkyl Imidazole Carboxylates

Regioselective N-carbamoylation of oxindoles was achieved through the use of imidazole carboxylate reagents. This reaction provides ready access to N-carbamoyl-3-monosubstituted oxindoles.
A fresh look at midpoint singularities in the algebra of string fields

In this paper we study the midpoint structure of the algebra of open strings using its formulation as a continuous Moyal product as described in [1]. We explain how poles in the open string non(anti)commutativity parameter correspond to certain ``null'' operators which annihilate the vertex, implying that states proportional to such operators tend to have vanishing star product with other string fields. We also identify in infinite sequence of new (anti)commutative coordinates and null operators for the star product in in the complex plane. These properties can be thought of as characteristic of the fact that the string is a continuous object and cannot be broken into ``halves'' as the split string intuition suggests. In fact, we show that the above properties can be anomalous if we invoke half-string degrees of freedom which cannot be represented with full string Fourier modes. The most prominent example occurs when multiplying a null operator with the identity string field.
How responsive are charitable donors to requests to give

Abstract People are more likely to contribute to a charity when they are asked to. Although this so-called ‘power of asking’ is well-known among fundraisers, the existing literature does not pay much attention to the role of donation requests in charitable giving. This paper uses a unique survey that includes a question on whether the respondent is asked to give to estimate the causal effects of charitable solicitations on giving behavior. In order to address the endogeneity of the donation requests due to non-random solicitation of charitable donors, I link this survey to IRS data on charitable organizations and propose identifying instruments. After controlling for the endogeneity, I find that donation requests increase the propensity to give by about nineteen percentage points for those who are asked to give. This effect is robust under different specifications and with different sets of instruments, and is much larger than the estimates from univariate models, which assume that charitable solicitations are exogenous. I argue that this result is counterintuitive and discuss some possible explanations.
Nickel Catalysis: Synergy between Method Development and Total Synthesis

Nickel(0) catalysts have proven to be powerful tools for multicomponent coupling reactions in our laboratories over the past 15 years. This interest was originally sparked by the ubiquity of allylic alcohol motifs in natural products, such as (-)-terpestacin, which we envisioned assembling by the coupling of two π components (alkyne and aldehyde) with concomitant reduction. Mechanistic investigations allowed us to elucidate several modes of controlling the regioselectivity and stereoselectivity in the oxidative cyclization, and these insights enabled us to leverage combinations of alkenes and phosphine ligands to direct regioselective outcomes. The initial success in developing the first intermolecular reductive alkyne-aldehyde coupling reaction launched a series of methodological investigations that rapidly expanded to include coupling reactions of alkynes with other electrophilic π components, such as imines and ketones, as well as electrophilic σ components, such as epoxides. Aziridines proved to be more challenging substrates for reductive coupling, but we were recently able to demonstrate that cross-coupling of aziridines and alkylzinc reagents is smoothly catalyzed by a zero-valent nickel/phenanthroline system. Moreover, the enantioselective alkyne-aldehyde coupling and the development of novel P-chiral ferrocenyl ligands enabled the total synthesis of (-)-terpestacin, amphidinolides T1 and T4, (-)-gloeosporone, and pumiliotoxins 209F and 251D. We subsequently determined that alkenes could be used in place of alkynes in several nickel-catalyzed reactions when a silyl triflate activating agent was added. We reason that such an additive functions largely to enhance the electrophilicity of the metal center by coordination to the electrophilic π component, such that less nucleophilic alkene π donors can undergo productive combination with nickel complexes. This activation manifold was further demonstrated to be effective for alkene-aldehyde couplings. In a related manner, electrophilic promoters were also successfully employed for allylic substitution reactions of allylic carbonates with simple alkenes and in the Mizoroki-Heck reaction of both benzyl and aryl electrophiles. In these instances, it is proposed that counterion exchange from a more strongly coordinating anion to the weakly or noncoordinating triflate counterion enables reaction at an electrophilic Ni(II) center rather than by coordination to one of the coupling components. Mechanistic insights also played an important role in the development of mixed N-heterocyclic carbene/phosphite ligand systems to overcome challenges in regioselective alkene-aldehyde coupling reactions. We hope that, taken together, the body of work summarized in this Account demonstrates the constructive interplay among total synthesis, methodological development, and mechanistic investigation that has driven our research program.
Adolescent risk perception, substance use, and educational attainment

This paper studies whether adolescents who are more aware of the risks on substance use in the early teenage years are later less likely to turn into binge drinkers or smokers. It also examines if reduction in substance use, due to high risk perception among adolescents, consequently improves their educational achievement. This research is important for two reasons. First, enhancing risk perception of substance use is an important strategy to prevent the youth from binge drinking and smoking. Second, adolescent substance use and educational achievement are key predictors of adulthood outcomes. We apply a bivariate probit model to a large representative dataset which codes youth risk perception, substance use, and educational attainment. The analysis shows high risk perception lowers the likelihood of substance use among the high school seniors. The resulting low alcohol use increases the chance of attending college and decreases the probability of dropping out of high school. The reduction in cigarette us...
Anomalous resistivity resulting from electrostatic ion cyclotron turbulence

Abstract An expression is found for the collisionless electrical resistivity resulting from a current driven electrostatic ion cyclotron instability.
New Cyanometalate Building Units: Synthesis and Characterization of [Re(CN)7]3- and [Re(CN)8]3-

Two new cyanorhenate complexes of potential utility in constructing magnetic and photomagnetic materials are reported. Reaction of (Bu4N)CN with [ReCl6]2- in acetonitrile affords yellow (Bu4N)3[Re(CN)7] (1), featuring the pentagonal bipyramidal complex [Re(CN)7]3-. The spectral and magnetic properties of 1 indicate that the complex has an S = 1/2 ground state with considerable anisotropy in the g tensor. In aqueous solution, 1 reacts with Mn2+ ions to generate the three-dimensional cyano-bridged solid [fac-Mn(H2O)3][cis-Mn(H2O)2][Re(CN)7]·3H2O (2) containing diamagnetic [Re(CN)7]4-. Addition of KIO4 to the reaction solution, originally intended to prevent reduction of the rhenium during solid formation, instead yields white (Bu4N)3[Re(CN)8] (3). As crystallized in K3[Re(CN)8]·2MeCN (4·2MeCN), the diamagnetic [Re(CN)8]3- complex adopts a nearly perfect square antiprismatic coordination geometry. In solution, this species behaves analogously to the isoelectronic [M(CN)8]4- (M = Mo, W) complexes, apparently ...
Phase singularities and termination of spiral wave reentry.

Phase Singularities and Termination of Reentry.Introduction: Recent defibrillation studies show that electric fields interact with reentrant activity in myocardial tissue through virtual electrode polarization (VEP). This study focuses on determining how VEP relates to the creation and survival of postshock phase singularities in cardiac tissue and demonstrating that interactions between VEP and preshock tissue state engender the probabilistic nature of defibrillation. Methods and Results: We constructed a two-dimensional tissue model representing a ventricular cross-section with fiber architecture and surrounding bath. We initiated spiral wave reentry and subjected the tissue to a monophasic shock. We estimated the shock success probability for a given strength by testing 16 coupling intervals throughout a single rotation of the wavefront. Over a range of shock strengths, our model exhibits dose-response behavior similar to experimental defibrillation efficacy curves. At the 50% effective strength (ED50), successful termination of reentry depends upon the interaction between preshock excitable gap and postshock phase singularities. We also found that increasing the stimulus strength toward ED50 increases the number of postshock singularities, whereas further strength increases above ED50 decrease the number of singularities. Conclusion: Our results show for the first time that a computational model can account for the probabilistic nature of defibrillation as VEP interacts with the dynamics of an ongoing reentrant wavefront. Further, we demonstrate that success of a shock depends on the annihilation of the phase singularities that arise after any strong stimulus. Our findings imply that VEP completely overrides the preshock tissue state in shocks that are highly likely to defibrillate (ED95).
An Algorithm for Detecting Quantum Gravity Photon Dispersion in Gamma-Ray Bursts: DisCan

DisCan is a new algorithm implementing photon dispersion cancellation in order to measure energy-dependent delays in variable sources. This method finds the amount of reversed dispersion that optimally cancels any actual dispersion present. It applies to any time- and energy-tagged photon data and avoids binning in both time and energy. The primary motivation here is the search for quantum gravity-based dispersion in future gamma-ray burst data from the Gamma-Ray Large Area Space Telescope (GLAST). Extrapolation of what is known about bursts at lower energies yields a reasonable prospect that photon dispersion effects consistent with some quantum gravity formalisms may be detected in sufficiently bright bursts. Short bursts have no or very small inherent lags and are therefore better prospects than long ones, but even they suffer a systematic error due to pulse asymmetry that may yield an irreducible uncertainty. We note that observations at TeV energies and higher will be useful for detecting dispersion in GRBs, using this and other algorithms, only if energy resolution can be improved over what is currently achieved.
Graph partitioning using single commodity flows

We show that the sparsest cut in graphs with n vertices and m edges can be approximated within O(log2n) factor in O(m + n3/2) time using polylogarithmic single commodity max-flow computations. Previous algorithms are based on multicommodity flows that take time O(m + n2). Our algorithm iteratively employs max-flow computations to embed an expander flow, thus providing a certificate of expansion. Our technique can also be extended to yield an O(log2n)-(pseudo-) approximation algorithm for the edge-separator problem with a similar running time.
Low-overhead hard real-time aware interconnect network router

The increasing complexity of embedded systems is accelerating the use of multicore processors in these systems. This trend gives rise to new problems such as the sharing of on-chip network resources among hard real-time and normal best effort data traffic. We propose a network-on-chip router that provides predictable and deterministic communication latency for hard real-time data traffic while maintaining high concurrency and throughput for best-effort/general-purpose traffic with minimal hardware overhead. The proposed router requires less area than non-interfering networks, and provides better Quality of Service (QoS) in terms of predictability and determinism to hard real-time traffic than priority-based routers. We present a deadlock-free algorithm for decoupled routing of the two types of traffic. We compare the area and power estimates of three different router architectures with various QoS schemes using the IBM 45-nm SOI CMOS technology cell library. Performance evaluations are done using three realistic benchmark applications: a hybrid electric vehicle application, a utility grid connected photovoltaic converter system, and a variable speed induction motor drive application.
Fluoride-promoted ligand exchange in diaryliodonium salts

Diaryliodonium salts are shown to undergo rapid, fluoride-promoted aryl exchange reactions at room temperature in acetonitrile. Aryl exchange is shown to be exquisitely sensitive to the concentration of fluoride ion in solution; fast exchange is observed as the fluoride concentration approaches a stoichiometric amount at 50 mM substrate concentration. The reaction is slowed, but not halted if benzene is the solvent, indicating that free fluoride ion or a four-coordinate anionic I(III) species may be responsible for the exchange. The fluoride-promoted aryl exchange reaction is general and allows direct measurement of the relative stabilities of diaryliodonium salts featuring different aryl substituents. The aryl exchange reaction may be of practical use for the preparation of hitherto inaccessible diaryliodonium salts, thus it also has implications for labeling radiotracers for molecular imaging with 18F-fluoride (t1/2 = 109.7 min).
Market Structures for U.S. Water Quality Trading

The use of transferable discharge permits as a water pollution control policy is rapidly increasing in the United States. Drawing on evidence from existing water quality trading programs, this paper provides a taxonomy of the forms that such markets take. Four main structures are identified: exchanges, bilateral negotiations, clearinghouses, and sole-source offsets. Each of these structures has its own strengths and weaknesses; none is optimal for all scenarios. Since market structure is largely determined by a program's rules, policy makers should be aware of the differences between these structures and the conditions under which each comes to be.
Experimental Study of Low Aspect Ratio Compressor Blading

The paper presents a study of low aspect blading for the inlet stages of a high pressure ratio, high-speed core compressor. The basic overall design variables were stage pressure ratio and blade aspect ratio; these four stages represent two levels of total pressure ratio, two levels of rotor blade aspect ratio, and two levels of stator vane aspect ratios. Comparisons of the overall performance, radial distributions of performance parameters, diffusion factors at the near-stall conditions, blade element data, and the axial distribution of rotor tip static pressures yielded the following results: (1) higher peak pressure ratio, high stage and rotor efficiencies, and greater stall margin were obtained with the lower aspect ratio blading, (2) the lower aspect ratio blading showed improved performance over the entire blade span, and (3) the lower aspect ratio rotors operated at higher diffusion factors and higher incidence angles over the entire blade span.
In-hospital resuscitation among the elderly: Substantial survival to hospital discharge

Abstract The appropriateness of aggressive resuscitation in many clinical settings has been questioned. Survival rates from cardiac arrest in the elderly are generally reported as poor, and satisfactory results from resuscitation attempts prolonged beyond 15 minutes are said to be rare. It was the purpose of this study to examine success rates for resuscitation in a cohort of elderly inpatients suffering cardiac arrest. We retrospectively reviewed 213 consecutive cardiac arrests occurring during a 12-month period in a single large tertiary private hospital. Patient age, presenting rhythm, and survival to hospital discharge were recorded. Elderly was defined as age 70 years or older. Cardiac arrests in the elderly totaled 89. Average age in this cohort was 76.2 ± 4.5 years. Eighteen patients (20.2%) had return of spontaneous circulation and 8 patients survived to hospital discharge (44.4% of those with return of spontaneous circulation). No significant difference in age or presenting rhythm of survivors versus nonsurvivors could be demonstrated, although a trend to more frequent ventricular fibrillation or ventricular tachycardia was seen ( P = .059, Fisher's exact). Time for resuscitation averaged 25.75 ± 9.2 minutes for survivors and 32.6 ± 22.1 minutes for nonsurvivors. Survival to hospital discharge occurs in 9% of in-hospital cardiac arrests in the elderly following average CPR times substantially in excess of 15 minutes.
Variations on Themes of Kostant

Let \( \mathfrak{g} \) be a complex semisimple Lie algebra, and let LG be a complex semisimple group with trivial center whose root system is dual to that of \( \mathfrak{g} \). We establish a graded algebra isomorphism \( H^{\raise0.145em\hbox{${\scriptscriptstyle \bullet}$}} {\left( {X_{\lambda } ,\mathbb{C}} \right)} \cong {{\text{S}}\mathfrak{g}^{e} } \mathord{\left/ {\vphantom {{{\text{S}}\mathfrak{g}^{e} } {I_{\lambda } }}} \right. \kern-\nulldelimiterspace} {I_{\lambda } } \), where Xλ is an arbitrary spherical Schubert variety in the loop Grassmannian for LG, and Iλ is an appropriate ideal in the symmetric algebra of \( \mathfrak{g}^{e} \), the centralizer of a principal nilpotent in \( \mathfrak{g} \). We also discuss a ‘topological’ proof of Kostant’s result on the structure of \( \mathbb{C}{\left[ \mathfrak{g} \right]} \).
Asymmetric synthesis of all four isomers of topographically constrained novel amino acids: β-isopropyltyrosines

Abstract All four stereoisomers of the highly constrained novel amino acid, β-isopropyltyrosine, have been synthesized with high stereoselectivities (>90% de) and in 40–50% overall yields by using the optically pure 4-phenyloxazolidinone as a chiral auxiliary via asymmetric Michael addition, direct or indirect azidation, hydrogenolysis and demethylation reactions.
Concise and stereospecific synthesis of novel bicyclic dideoxynucleosides as potential antiviral agents

Abstract A novel class of dideoxynucleosides containing a bicyclic sugar moiety, structurally related to the natural griseolic acids, was synthesized starting from the stereochemically defined compound, 1,4:3,6-dianhydro-D-glucitol. The key intermediate in the synthesis was a [3.3.0] fused bicyclic glycal. Glycosylation of this compound with nucleobase proceeded both regiospecifically and stereospecifically in the presence of an auxiliary agent, N-iodosuccinamide. Changes in stereochemistry during the synthesis was monitored by optical rotation data and confirmed by both 1D and 2D NMR experiments. The synthetic approach described possesses general usefulness.
ON MULTI-COLOR PARTITIONS AND THE GENERALIZED ROGERS–RAMANUJAN IDENTITIES

Basil Gordon, in the sixties, and George Andrews, in the seventies, generalized the Rogers–Ramanujan identities to higher moduli. These identities arise in many areas of mathematics and mathematical physics. One of these areas is representation theory of infinite dimensional Lie algebras, where various known interpretations of these identities have led to interesting applications. Motivated by their connections with Lie algebra representation theory, we give a new interpretation of a sum related to generalized Rogers–Ramanujan identities in terms of multi-color partitions.
Nano-Graphene Oxide for Cellular Imaging and Drug Delivery.

Two-dimensional graphene offers interesting electronic, thermal, and mechanical properties that are currently being explored for advanced electronics, membranes, and composites. Here we synthesize and explore the biological applications of nano-graphene oxide (NGO), i.e., single-layer graphene oxide sheets down to a few nanometers in lateral width. We develop functionalization chemistry in order to impart solubility and compatibility of NGO in biological environments. We obtain size separated pegylated NGO sheets that are soluble in buffers and serum without agglomeration. The NGO sheets are found to be photoluminescent in the visible and infrared regions. The intrinsic photoluminescence (PL) of NGO is used for live cell imaging in the near-infrared (NIR) with little background. We found that simple physisorption via π-stacking can be used for loading doxorubicin, a widely used cancer drug onto NGO functionalized with antibody for selective killing of cancer cells in vitro. Owing to its small size, intrinsic optical properties, large specific surface area, low cost, and useful non-covalent interactions with aromatic drug molecules, NGO is a promising new material for biological and medical applications.
Energy relaxation in galaxies induced by an external environment and/or incoherent internal pulsations

This paper explores the phenomenon of energy relaxation for stars in a galaxy embedded in a high-density environment that is subjected continually to perturbations reflecting the presence of other nearby galaxies and/or incoherent internal pulsations. The analysis is similar to earlier analyses of energy relaxation induced by binary encounters between nearby stars and between stars and giant molecular clouds in that the perturbations are idealized as a sum of near-random events which can be modelled as diffusion and dynamical friction. However, the analysis differs in one important respect: because the time-scale associated with these perturbations need not be short compared with the characteristic dynamical time tD for stars in the original galaxy, the diffusion process cannot be modelled as resulting from a sequence of instantaneous kicks, i.e. white noise. Instead, the diffusion is modelled as resulting from random kicks of finite duration, i.e. coloured noise, characterized by a non-zero autocorrelation time tc. A detailed analysis of coloured noise generated by sampling an Ornstein–Uhlenbeck process leads to a simple scaling in terms of tc and an effective diffusion constant D. Interpreting D and tc following early work by Chandrasekhar (the ‘nearest neighbour approximation’) implies that, for realistic choices of parameter values, energy relaxation associated with an external environment and/or internal pulsations could be important on times short compared with the age of the Universe.
A New Preparation of gem-bis(Difluoramino)- alkanes via Direct Fluorination of Geminal Bisacetamides

Abstract A fundamentally new preparation of internal and terminal gem-bis- (difluoramino)alkanes has been demonstrated by the direct fluorination of corresponding gem-bisacetamides, specifically, 1,1-bisacetamidocyclohexane and 1,1-bisacetamidopropane, leading to 1,1-bis(difluoramino)cyclohexane and 1,1-bis(difluoramino)- propane, respectively.
RIO: the R-process isotope observer

Abstract Our galaxy is filled with a “gas” of relativistic nuclei and electrons – the galactic cosmic rays (GCRs). The source of GCR nuclei is unknown, but there is a general consensus among high-energy astrophysicists that GCRs are accelerated by supernova (SN) shocks in the interstellar medium. The evidence in support of this picture is strong but indirect. However, the fact that the cosmic-ray spectrum extends continuously, without steps or peaks, to more than five orders of magnitude in energy beyond the limit of SN shock acceleration appears to be incompatible with this picture, at least without extreme fine-tuning of models. A “smoking gun” is needed to definitively establish that SN shocks are indeed the accelerator of GCRs. If GCRs are accelerated in SN shocks, they will be enhanced in freshly-synthesized r-process material. We are currently studying the R-process Isotope Observer (RIO) as a Mission of Opportunity for the International Space Station. RIO will make the first measurements of the isotopic abundances of the “ultraheavy” GCRs (those in the range 32 ⩽ Z ⩽ 42) and will determine the fractional contribution of freshly-synthesized r-process material in GCRs through the measurement of several key isotopic ratios.
The Geometry of Physics: An Introduction

Preface Part I. Manifolds, Tensors and Exterior Forms: 1. Manifolds and vector fields 2. Tensors and exterior forms 3. Integration of differential forms 4. The Lie derivative 5. The Poincare Lemma and potentials 6. Holonomic and non-holonomic constraints Part II. Geometry and Topology: 7. R3 and Minkowski space 8. The geometry of surfaces in R3 9. Covariant differentiation and curvature 10. Geodesics 11. Relativity, tensors, and curvature 12. Curvature and topology: Synge's theorem 13. Betti numbers and De Rham's theorem 14. Harmonic forms Part III. Lie Groups, Bundles and Chern Forms: 15. Lie groups 16. Vector bundles in geometry and physics 17. Fiber bundles, Gauss-Bonnet, and topological quantization 18. Connections and associated bundles 19. The Dirac equation 20. Yang-Mills fields 21. Betti numbers and covering spaces 22. Chern forms and homotopy groups Appendix: forms in continuum mechanics.
Relevance Sensitive Non-Monotonic Inference on Belief Sequences

We present a method for relevance sensitive non-monotonic inference from belief sequences which incorporates insights pertaining to prioritized inference and relevance sensitive, inconsistency tolerant belief revision. Our model uses a finite, logically open sequence of propositional formulas as a representation for beliefs and defines a notion of inference from maxiconsistent subsets of formulas guided by two orderings: a temporal sequencing and an ordering based on relevance relations between the putative conclusion and formulas in the sequence. The relevance relations are ternary (using context as a parameter) as opposed to standard binary axiomatizations. The inference operation thus defined easily handles iterated revision by maintaining a revision history, blocks the derivation of inconsistent answers from a possibly inconsistent sequence and maintains the distinction between explicit and implicit beliefs. In doing so, it provides a finitely presented formalism and a plausible model of reasoning for...
THE MICROWAVE SPECTRUM OF CYCLOBUTADIENE IRON TRICARBONYL

Abstract The rotational spectrum of cyclobutadiene iron tricarbonyl was measured using a Flygare-Balle-type microwave spectrometer. Twenty a -dipole transitions were measured in the 5–16 GHz range for this prolate symmetric-top molecule. A least-squares fit of the data to a distortable symmetric top Hamiltonian yielded B = 961.9856(8) MHz, D J = 0.184(8) kHz, D JK = 1.20(3) kHz. These results indicate that the vibrationally averaged structure of the cyclobutadiene ring is square and perpendicular to the a -molecular axis.
Distant Companions and Planets around Millisecond Pulsars

We present a general method for determining the masses and orbital parameters of binary millisecond pulsars with long orbital periods (Porb 1 yr), using timing data in the form of pulse frequency derivatives. Our method can be used even when the available timing data cover only a small fraction of an orbit, but it requires high-precision measurements of up to five successive derivatives of the pulse frequency. With five derivatives a complete determination of the mass and orbital parameters is in principle possible (up to the usual inclination factor sin i). With less than five derivatives, only partial information can be obtained, but significant constraints can sometimes be placed on, e.g., the mass of the companion. We apply our method to analyze the properties of the second companion in the PSR B1620-26 triple system. We use the latest timing data for this system, including a recent detection of the fourth time derivative of the pulse frequency, to constrain the mass and orbital parameters of the second companion. We find that all possible solutions have a mass m2 in the range 2.4 × 10-4 M☉ ≤ m2 sin i2 ≤ 1.2 × 10-2 M☉, i.e., almost certainly excluding a second companion of stellar mass and suggesting instead that the system contains a planet or brown dwarf. To further constrain this system, we have used preliminary measurements of the secular perturbations of the inner binary. Using Monte Carlo realizations of the triple configuration in three dimensions, we find the most probable value of m2 to be 0.01 ± 0.005 M☉, corresponding to a distance of 38 ± 6 AU from the center of mass of the inner binary (the errors indicate 80% confidence intervals). We also apply our method to analyze the planetary system around PSR B1257+12, where a distant, giant planet may be present in addition to the three well-established Earth-mass planets. We find that the simplest interpretation of the frequency derivatives implies the presence of a fourth planet with a mass of ~100 M⊕ in a circular orbit of radius ~40 AU.
Valence Resonance States of N2

Resonant scattering observed in the transmission of electrons between 9 and 11 eV in collision with N2 has been attributed to the attachment of the scattered electron to an excited valence state. Resonance valence excited states of N2(-) are calculated that could support this hypothesis. Although calculated and observed resonance energies are in close agreement, the calculations do not reflect the observed complex angular behavior of the scattered electron.
Snowboarding: The Construction of Gender in an Emerging Sport

Previous research has identified sport as a practice that creates and legitimizes notions of male dominance. However, gender is constructed and resisted differently within various sporting activities. This article addresses the diversity of masculinities in sport through an exploration of the construction of gender in an emerging sport—snowboarding. The analysis identifies four social practices used by male snowboarders to construct their sport as a masculine practice: (a) appropriation of other cultural masculinities, (b) interaction and clothing styles, (c) violence and aggression, and (d) emphasized heterosexuality. The findings indicate that the historical context of snowboarding and the social class, race-ethnicity, and age of snowboarding participants influence the social practices used to create masculinity. Although snowboarders rely on different social practices to construct masculinity than those used in organized sports, these practices also serve to support notions of male dominance and differ...
Operations for inference in continuous Bayesian networks with linear deterministic variables

An important class of continuous Bayesian networks are those that have linear conditionally deterministic variables (a variable that is a linear deterministic function of its parents). In this case, the joint density function for the variables in the network does not exist. Conditional linear Gaussian (CLG) distributions can handle such cases when all variables are normally distributed. In this paper, we develop operations required for performing inference with linear conditionally deterministic variables in continuous Bayesian networks using relationships derived from joint cumulative distribution functions. These methods allow inference in networks with linear deterministic variables and non-Gaussian distributions.
Pupukeamide, a linear tetrapeptide from a cephalaspidean mollusk Philinopsis speciosa

Abstract A linear peptide pupukeamide (1) was isolated from a cephalaspidean mollusk Philinopsis speciosa. Its structure was elucidated by spectroscopic and chemical methods.
Impact of flexibility on the aerodynamics of an aspect ratio two membrane wing

Abstract Development of an aeroelastic solver with application to flexible membrane wings for micro air vehicles is presented. A high-order (up to sixth order) Navier–Stokes solver is coupled with a geometrically nonlinear p-version Reissner–Mindlin finite element plate model to simulate the highly flexible elastic membrane. An implicit LES approach is employed to compute the mixed laminar/transitional/turbulent flowfields present for the low Reynolds number flows associated with micro air vehicles. Computations are performed for an aspect ratio two membrane wing at angles of attack α = 10 ° , 16° and 23° for a Reynolds number, Re = 24 300 . Comparisons of the computational results with experimental PIV and surface deflection measurements demonstrated reasonable agreement. Reduced separation and enhanced lift are obtained due to favorable interactions between the flexible membrane wing and the unsteady flow over the wing. The impact of flexibility on the aerodynamic performance comes primarily from the development of mean camber with some further effects arising from the interaction between the dynamic motion of the membrane and the unsteady flowfield above. At lower angles of attack this lift enhancement comes at the cost of reduced L/D. The nose-down pitching moment increases with flexibility at the lowest angle of attack but is reduced for the higher two angles of attack. These results suggest that membrane flexibility might provide a means to reduce the impact of a strong gust encounter by maintaining lift and reducing the effect of the gust on pitching moment.
The undecidability of the semi-unification problem

Abstract The Semi-Unification Problem (SUP) is a natural generalization of both first-order unification and matching. The problem arises in various branches of computer science and logic. Although several special cases of SUP are known to be decidable, the problem in general has been open for several years. We show that SUP in general is undecidable, by reducing what we call the "boundedness problem" of Turing machines to SUP. The undecidability of this boundedness problem is established by a technique developed in the mid-1960s to prove related results about Turing machines
Lattice Boltzmann Method for 3-D Flows with Curved Boundary

In this work, we investigate two issues that are important to computational efficiency and reliability in fluid dynamic applications of the lattice Boltzmann equation (LBE): (1) Computational stability and accuracy of different lattice Boltzmann models and (2) the treatment of the boundary conditions on curved solid boundaries and their 3-D implementations. Three athermal 3-D LBE models (Q15D3, Q19D3, and Q27D3) are studied and compared in terms of efficiency, accuracy, and robustness. The boundary treatment recently developed by Filippova and Hanel (1998, J. Comp. Phys.147, 219) and Mei et al. (1999, J. Comp. Phys.155, 307) in 2-D is extended to and implemented for 3-D. The convergence, stability, and computational efficiency of the 3-D LBE models with the boundary treatment for curved boundaries were tested in simulations of four 3-D flows: (1) Fully developed flows in a square duct, (2) flow in a 3-D lid-driven cavity, (3) fully developed flows in a circular pipe, and (4) a uniform flow over a sphere. We found that while the 15-velocity 3-D (Q15D3) model is more prone to numerical instability and the Q27D3 is more computationally intensive, the Q19D3 model provides a balance between computational reliability and efficiency. Through numerical simulations, we demonstrated that the boundary treatment for 3-D arbitrary curved geometry has second-order accuracy and possesses satisfactory stability characteristics.
Enhanced Privacy ID: A Direct Anonymous Attestation Scheme with Enhanced Revocation Capabilities

Direct Anonymous Attestation (DAA) is a scheme that enables the remote authentication of a Trusted Platform Module (TPM) while preserving the user's privacy. A TPM can prove to a remote party that it is a valid TPM without revealing its identity and without linkability. In the DAA scheme, a TPM can be revoked only if the DAA private key in the hardware has been extracted and published widely so that verifiers obtain the corrupted private key. If the unlinkability requirement is relaxed, a TPM suspected of being compromised can be revoked even if the private key is not known. However, with the full unlinkability requirement intact, if a TPM has been compromised but its private key has not been distributed to verifiers, the TPM cannot be revoked. Furthermore, a TPM cannot be revoked from the issuer, if the TPM is found to be compromised after the DAA issuing has occurred. In this paper, we present a new DAA scheme called Enhanced Privacy ID (EPID) scheme that addresses the above limitations. While still providing unlinkability, our scheme provides a method to revoke a TPM even if the TPM private key is unknown. This expanded revocation property makes the scheme useful for other applications such as for driver's license. Our EPID scheme is efficient and provably secure in the same security model as DAA, i.e., in the random oracle model under the strong RSA assumption and the decisional Diffie-Hellman assumption.
An Experimental Study of the Shock Structure in a Partially Ionized Gas

Shock structure experiments were carried out in a radio-frequency-heated, steady-state, low-density, partially-ionized argon plasma jet. The primary diagnostic tool was a cylindrical free molecule Langmuir probe aligned with the flow, which was used to probe a normal shock wave. Spatial resolution was 13% of the heavy-particle shock thickness; thus, details of electron temperature, ion number density, and plasma potential were obtained through the shock. The electron temperature rise was observed to precede the heavy-particle shock. The plasma potential converted from floating potential according to the theory of Laframboise was in substantial agreement with changes in plasma potential obtained from a numerical quadrature of the generalized Ohm's law assuming zero current. An explanation of the dark space observed to precede partially ionized gas shocks is provided by comparing the collisional-radiative recombination rate calculated with observed electron temperature and number density to the luminosity of the flow. The integration of the electron energy equation, including the effect of recombination energy transfer, was found to be in substantial agreement with the data.
Novel 2- and 5-azido-N-(diphenylcarbamoyl)proline methyl esters. Examples of a novel proline oxidation.

The crystal structures of two azido-substituted proline derivatives are reported. Racemic 2-azido-1-(diphenylcarbamoyl)proline methyl ester, (I), C 19 H 19 N 5 O 3 , is resolved upon crystallization from methylene chloride-diethyl ether. The azido moieties are nonlinear with N-N-N angles of 173 (1) and 170.3 (2)° for (I) and (II) [cis-5-azido-N-(diphenylcarbamoyl)proline methyl ester, C 19 H 19 N 5 O 3 ], respectively. Close intramolecular contacts between the carbonyl O atom of the amide and the central N atom of the azido group are found. The contact distances between N7 and O14 are 2.780(14) and 2.815 (2) A for (I) and (II), respectively.
Simple-current symmetries, rank-level duality, and linear skein relations for Chern-Simons graphs

Abstract A previously proposed two-step algorithm for calculating the expectation values of arbitrary Chern-Simons graphs fails to determine certain crucial signs. The step which involves calculating tetrahedra by solving certain non-linear equations is repaired by introducing additional linear equations. The step which involves reducing arbitrary graphs to sums of products of tetrahedra remains seriously disabled, apart from a few exceptional cases. As a first step towards a new algorithm for general graphs we find useful linear equations for those special graphs which support knots and links. Using the improved set of equations for tetrahedra we examine the symmetries between tetrahedra generated by arbitrary simple currents. Along the way we describe the simple, classical origin of simple-current charges. The improved skein relations also lead to exact identities between planar tetrahedra in level K G(N) and level N G(K) Chern-Simons theories, where G(N) denotes a classical group. These results are recast as WZW braid-matrix identities and as identities between quantum 6-jsymbols at appropriate roots of unity. We also obtain the transformation properties of arbitrary graphs, knots, and links under simple-current symmetries and rank-level duality. For links with knotted components this requires precise control of the braid eigenvalue permutation signs, which we obtain from plethysm and an explicit expression for the (multiplicity-free) signs, valid for all compact gauge groups and all fusion products.
Bayesian hierarchical distributed lag models for summer ozone exposure and cardio-respiratory mortality

In this article we develop Bayesian hierarchical distributed lag models for estimating associations between daily variations in summer ozone levels and daily variations in cardiovascular and respiratory (CVDRESP) mortality counts for 19 large U.S. cities included in the National Morbidity, Mortality and Air Pollution Study (NMMAPS) for the summers of 1987-1994. In the first stage, we define a semi-parametric distributed lag Poisson regression model to estimate city-specific relative rates of CVDRESP mortality associated with short-term exposure to summer ozone. In the second stage, we specify a class of distributions for the true city-specific relative rates to estimate an overall effect by taking into account the variability within and across cities. We perform the calculations with respect to several random effects distributions (normal, t-student, and mixture of normal), thus relaxing the common assumption of a two-stage normal-normal hierarchical model. We assess the sensitivity of the results to: (i) lag structure for ozone exposure; (ii) degree of adjustment for long-term trends; (iii) inclusion of other pollutants in the model; (iv) heat waves; (v) random effects distributions; and (vi) prior hyperparameters. On average across cities, we found that a 10ppb increase in summer ozone level over the previous week is associated with a 1.25 per cent increase in CVDRESP mortality (95 per cent posterior regions: 0.47, 2.03). The relative rate estimates are also positive and statistically significant at lags 0, 1 and 2. We found that associations between summer ozone and CVDRESP mortality are sensitive to the confounding adjustment for PM10, but are robust to: (i) the adjustment for long-term trends, other gaseous pollutants (NO2, SO2 and CO); (ii) the distributional assumptions at the second stage of the hierarchical model; and (iii) the prior distributions on all unknown parameters. Bayesian hierarchical distributed lag models and their application to the NMMAPS data allow us to estimate of an acute health effect associated with exposure to ambient air pollution in the last few days on average across several locations. The application of these methods and the systematic assessment of the sensitivity of findings to model assumptions provide important epidemiological evidence for future air quality regulations.
Microscopic description of induced fission

Selected aspects of the description of neutron-induced fission in 240Pu in the framework of the nuclear energy density functional theory at finite temperature are presented. In particular, we discuss aspects pertaining to the choice of thermodynamic state variables, the evolution of fission barriers as function of the incident neutron energy, and the temperatures of the fission fragments.
Spectral dependence of spatially-incoherent modulation instability

We present the first experimental study of spatially-incoherent modulation instability for different spectral distributions. Characteristic behavior depends sensitively on the underlying profiles. The setup and results introduce a new experimental degree-of-freedom into nonlinear statistical optics.
Implementations of mesh refinement schemes for Particle-In-Cell plasma simulations ☆

Abstract Plasma simulations are often rendered challenging by the disparity of scales in time and in space which must be resolved. When these disparities are in distinctive zones of the simulation region, a method which has proven to be effective in other areas (e.g., fluid dynamics simulations) is the mesh refinement technique. We briefly discuss the challenges posed by coupling this technique with plasma Particle-In-Cell simulations and present two implementations in more detail, with examples.
Faster background determination––a method for gaining time coverage and flux measurement accuracy with Cherenkov telescopes

An improved way of taking off-source data for background determination in Cherenkov telescope (CT) observations is proposed. Generalizing the traditional concept of taking on-source/off-source observations of equal duration (e.g. 30 min ON followed by 30 min OFF), faster background determination permits an off-source observation with the same zenith angle distribution as the on-source observation to be obtained within less time. The method permits the on-source observation time to be maximized without compromising the quality of the background determination. It also increases the signal significance for strong sources. The only modification necessary in the data acquisition is a small change to the tracking algorithm. The only modification necessary in the data analysis is to introduce a time normalization which does not increase the systematic errors. The method could become the normal observing mode for CTs when observing strong sources.