cssi/SciSciGPT-SciSciNet huggingface dataset:
Simulation Codes For Modeling Free-Electron Laser Oscillators

This paper reviews the basic characteristics of free-electron laser (FEL) oscillators, and describes a group of codes that have been developed to analyze and design rf-linac-driven FELs. The optical performance of an FEL has been treated using 1-D time-dependent (finite pulse) codes that describe the characteristics of the optical temporal pulse shape and spectrum during the evolution of the oscillator from, low-intensity small-signal gain conditions to high-intensity large-signal gain conditions. These codes can include frequency-dependent elements, such as narrow-band filters or grating rhombs. Diffraction effects, transverse optical and electron-beam mode properties, misalignments, as well as aberrations on optical elements are modeled with the 3-D code FELEX. This code has now been extended to include effects of imperfections in the wiggler magnetic field and light emission at higher optical harmonics. A separate accelerator modeling capability allows the use of a numerically-generated electron pulse in FELEX for 3-D integrated numerical FEL simulations. 26 refs., 10 figs.
Use of Electrochemical Methods as an Alternative to Tin Reagents for the Reduction of Vinyl Halides in Inositol Synthons.

Several vinyl halides previously used in inositol syntheses were subjected to electrochemical reduction. The unreactivity of allylic alcohols or allylic ethers at the applied potentials allowed the...
On the explicit construction of higher deformations of partition statistics

The modularity of the partition-generating function has many important consequences: for example, asymptotics and congruences for p(n). In a pair of articles, Bringmann and Ono [11], [12] connected the rank, a partition statistic introduced by Dyson [18], to weak Maass forms, a new class of functions that are related to modular forms and that were first considered in [14]. Here, we take a further step toward understanding how weak Maass forms arise from interesting partition statistics by placing certain 2-marked Durfee symbols introduced by Andrews [1] into the framework of weak Maass forms. To do this, we construct a new class of functions that we call quasi-weak Maass forms because they have quasi-modular forms as components. As an application, we prove two conjectures of Andrews [1, Conjectures 11, 13]. It seems that this new class of functions will play an important role in better understanding weak Maass forms of higher weight themselves and also their derivatives. As a side product, we introduce a new method that enables us to prove transformation laws for generating functions over incomplete lattices
Transonic Euler solutions on mutually interfering finned bodies

Abstract : The ability of an Euler code to predict mutual aerodynamic interference in the transonic regime was investigated. One, two, and three body combinations of a cruciform finned configuration were examined at Mach numbers from 0.80 to 1.20 and angles of attack up to ten degrees. Predicted surface pressure distributions were compared with wind tunnel data or the first time on three finned bodies with success. The Euler code was found to predict body pressures well in many interference regions, although shock location often was less accurate due to viscous effects int he strongest interference flow field near Mach 1. Rigid body physics of the three body combination was investigated from integrated pressure distributions. Force and moment behavior was found to be strongly dependent upon Mach number. Keywords: Numerical grid generation; Euler equations; Mutual interference; Finned bodies; Transonic flows. (JHD)
Fabrication and characterization of singly addressable arrays of polysilicon field-emission cathodes

Abstract Polysilicon is a viable candidate material for field-emission microelectronics devices. It can be competitive for large size, cost-sensitive applications such as flat-panel displays and micro electro-mechanical systems. Singly addressable arrays of field-emission cells were fabricated in a matrix configuration using a subtractive process on polysilicon-on-insulator substrates. Matrix rows were fabricated as insulated polycrystalline silicon stripes with sharp emission tips; and matrix columns were deposited as gold thin film electrodes with round gate openings. Ion implantation has been used to provide the required conductivity of the polysilicon layer. To reduce radius of curvature of the polysilicon tips, an oxidation sharpening process was used. The final device had polysilicon emission tips with end radii smaller than 15 nm, surrounded by gate apertures of 0.4 μm in diameter. Field emission properties of the cathodes were measured at a pressure of about 10−8 Torr, to emulate vacuum conditions available in sealed vacuum microelectronics devices. It was found that an emission current of 1 nA appears at a gate voltage of 25 V and can be increased up to 1 μA at 70 V. Over this range of current, no “semiconductor” deviation from the Fowler–Nordheim equation was observed. I–V characteristics measured in cells of a 10×10 matrix, with a cell spacing of 50 μm demonstrated reasonable uniformity and reproducibility.
Getting a Grip on the Saddle: Chasms or Cycles?

Abstract The “saddle” is a sudden, sustained, and deep drop in sales of a new product, after a period of rapid growth following takeoff, followed by a gradual recovery to the former peak. The authors test for the generalizability of the saddle across products and countries and for three rival explanations: chasms in adopter segments, business cycles, and technological cycles. They model both boundary points of the saddle—start of the sales drop and recovery to the initial peak—using split-population models. Empirical analysis of historical sales data from ten products across 19 countries shows that the saddle is fairly pervasive. The onset of the saddle occurs in 148 product–country combinations. On average, the saddle occurs nine years after takeoff, at a mean penetration of 30%, and it lasts for eight years with a 29% drop in sales at its depth. The results support explanations of chasms and technological cycles for information/entertainment products and business cycles and technological cycles for kitc...
Phase structure of (2 + 1)d strongly coupled lattice gauge theories

Abstract We study the chiral phase transition in (2 + 1) d strongly coupled U(N) lattice gauge theories with staggered fermions. We show with high precision simulations performed directly in the chiral limit that these models undergo a Berezinski-Kosterlitz-Thouless (BKT) transition. We also show that this universality class is unaffected even in the large N limit.
Generalizations of Graham’s pebbling conjecture

Abstract We investigate generalizations of pebbling numbers and of Graham’s pebbling conjecture that π ( G □ H ) ≤ π ( G ) π ( H ) , where π ( G ) is the pebbling number of the graph G . We develop new machinery to attack the conjecture, which is now twenty years old. We show that certain conjectures imply others that initially appear stronger. We also find counterexamples that shows that Sjostrand’s theorem on cover pebbling does not apply if we allow the cost of transferring a pebble from one vertex to an adjacent vertex to depend on the weight of the edge and we describe an alternate pebbling number for which Graham’s conjecture is demonstrably false.
The Density Spike in Cosmic-Ray-Modified Shocks: Formation, Evolution, and Instability

We examine the formation and evolution of the density enhancement (density spike) that appears downstream of strong, cosmic-ray-modified shocks. This feature results from temporary overcompression of the flow by the combined cosmic-ray shock precursor and gas subshock. Formation of the density spike is expected whenever shock modification by cosmic-ray pressure increases strongly. That occurrence may be anticipated for newly generated strong shocks, or for strong shocks or cosmic-ray-modified shocks encountering a region of higher external density, for example. The predicted mass density within the spike increases with the shock Mach number and with shocks more dominated by cosmic-ray pressure. For very strong shocks, the total compression compared to the upstream gas may approach D(γg + 1)/(γg - 1) during the formation period, where γg is the gas adiabatic index and D is the compression ratio through the precursor. As the full shock reaches equilibrium, the spike detaches, lags behind the modified shock transition, and is further compressed, so that the density can exceed the limit quoted above. We find this spike to be linearly unstable under a modified Rayleigh-Taylor instability criterion at the early stage of its formation. Our linear analysis shows that the flow is unstable when the gradients of total pressure (gas pressure + cosmic-ray pressure) and gas density have opposite signs. We confirm this numerically using two independent codes based on the two-fluid model for cosmic-ray transport. These two-dimensional simulations show that the instability grows impulsively at early stages and then slows down as the gradients of total pressure and gas density decrease. Flow within the density spike becomes disordered through the instability. It seems likely that this can significantly increase the local magnetic field beyond compressional effects. Observational discovery of this unstable density spike behind shocks, possibly through radio emission enhanced by the amplified magnetic fields, would provide evidence for the existence of strongly cosmic-ray-modified shock structures.
Efficacy and safety of amphotericin B lipid complex injection (ABLC) in solid-organ transplant recipients with invasive fungal infections.

Background Fungal infections following solid-organ transplantation are a major source of morbidity and mortality. This report describes the efficacy and safety of Amphotericin B Lipid Complex Injection (ABLC) in solid-organ transplant recipients. Methods Three open-label, second-line treatment studies evaluated ABLC as a treatment for severe, life-threatening mycoses in patients who were refractory to or intolerant to conventional antifungal (mostly amphotericin B [AmB]) therapy or had pre-existing renal disease. Results The 79 solid-organ transplant recipients (25 heart, 20 liver, 17 kidney, 11 lung, 5 multiple, 1 pancreas) who received ABLC in these studies had the following fungal infections: aspergillosis (n = 39); candidiasis (n = 20); zygomycosis (n = 8); cryptococcosis and histoplasmosis (n = 3 each); and blastomycosis, cladosporiosis, fusariosis, Bipolaris hawaiiensis, Dactylaria gallopava, and an unspecified fungal infection (n = 1 each). The median duration of ABLC therapy was 28 d (1-178 d). The daily dose ranged between 1.6 and 7.4 mg/kg (median, 4.6 mg/kg). The clinical response rate for the patients who could be assessed was 58% (39/67). Clinical response rates for heart, liver, kidney, and lung recipients were 59, 60, 67, and 40%, respectively; response rates for aspergillosis and candidiasis were 47 and 71%, respectively. Forty-six of the 79 patients (58%) survived for more than 28 d after the last dose of ABLC. Mean baseline serum creatinine was 3.2 mg/dL; 64 patients (81%) had stable (n = 37) or improved (n = 27) serum creatinine at the end of treatment. Conclusions ABLC is safe and effective treatment for fungal infections in solid-organ transplant recipients. Its renal-sparing properties are particularly suited for this high-risk population for renal failure.
Failure Analysis of Tubular Hydroforming

A mathematical analysis of failure developments for tubular hydroforming under combined internal pressure and end feeding is presented in this paper. Under considerations are two distinct failure modes, namely, the bursting and the wrinkling. Bursting is an instability phenomenon where the tube can't sustain any increased tensile loading. Splitting usually follows due to extreme deformations in the bursting area. Wrinkling is due to high compression load, which deteriorates the quality of the final product. The deformation theory of plasticity is utilized in this study and the material anisotropy is accounted for in the constitutive model. The governing equations for the onset of both failure modes are established. The results are presented as Hydroforming Failure Diagram in the End Feed-Internal Pressure space. A parametric study of the failure criteria for a variety of materials and process parameters is performed. It is shown that the material anisotropy plays a significant role. The results provide guidelines for product designers and process engineers for the avoidance of failure during hydroforming. The validity and applicability of current study are also discussed.
Mechanical behavior and microstructure of SiC and SiC/TiB2 ceramics

Abstract Toughness characteristics and associated microstructural behavior in two kinds of SiC and TiB2 particulate-reinforced SiC composites were studied. From indentation- strength tests, the Al2O3-doped, high volume fraction β- SiC TiB 2 showed a distinctive flaw tolerance and a higher retained strength in the long-crack region, as compared with β-SiC alone. On the other hand, the boron- and carbon-doped, low volume fraction, α- SiC TiB 2 exhibited a higher retained strength without an apparent improvement in flaw tolerance, as compared with α-SiC. Crack bridging and sliding and pullout of TiB2 particulates toughened the β- SiC TiB 2 , while only crack bridging by TiB2 occurred in α- SiC TiB 2 with difficulty in grain sliding and pullout. A quantitative evaluation of the indentation-strength data revealed a sharp rising toughness curve for β- SiC TiB 2 . The enhanced long-crack toughness originated from the weak interface created by the TiB2 and sintering additives.
Fabricating Neural and Cardiomyogenic Stem Cell Structures by a Novel Rapid Prototyping—the Inkjet Printing Method

Abstract : Direct printing of living cardiomyogenic stem cells and embryonic cortical neurons to generate complex cellular patterns and structures of such cells was demonstrated in the study. Furthermore, the immunostaining analyses and the whole-cell patch clamp recordings showed the cortical neurons grown in the printed cellular patterns and structures maintained their basic cellular functions, including neuronal phenotypes and electrophysiological properties. These results and findings may greatly prompt the inkjet printing method evolving into a viable and cost-effective approach for engineering human neural and cardiac tissues or even organs.
Indole-Diterpene Synthetic Studies: Total Synthesis of (−)-21-Isopentenylpaxilline

An efficient, stereocontrolled total synthesis of the complex indole-diterpene alkaloid (−)-21-isopentenylpaxilline (1) has been achieved. Key elements of the synthesis include the stereocontrolled construction of the advanced eastern hemisphere (−)-68, involving a highly efficient union of the eastern and western fragments (−)-68 and 5 exploiting our 2-substituted indole synthesis, application of the Negishiπ cycloalkylation tactic as a new, potentially general protocol for the construction of ring C, and the fragmentation of a β,γ-epoxy ketone to introduce the tertiary OH group at C(13) in the indole diterpene skeleton.
Synthesis and metal-complexing ability of m-xylylenebis(β-diketones)

The preparation of the bis(β-diketone) XBAH2 (3,3′-[1,3-phenylenebis(methylene) bis(2,4-pentanedione)]) and five of its derivatives, and a study of their complexation reactions with Cu2+, is reported. Of these ligands (LH2), only sterically unhindered derivatives of acetylacetone readily yield binuclear copper(II) complexes, Cu2L2. The introduction of bulkier groups (Ph, t-Bu) into the 2,4-pentanedione portions of the ligands inhibits the complex-forming reaction, resulting in lower yields (XBBH2; see ligand abbreviations in Fig. 1), no reaction (XBPH2) or decomposition (XBDH2). The copper complex of Cl4XBAH2 appears to be polymeric; this is probably due to the steric effects of the bulky chlorine atom in the two-position.
UROLOGICAL ANOMALIES IN THE CAUDAL REGRESSION SYNDROME

Two cases of unusual urological anomalies seen in association with the caudal regression syndrome are reported. One patient had bilateral single ectopic ureters with unilateral renal agenesis and the other a megalo-ureter secondary to a ureteric valve.
On the origin of the local group's peculiar velocity

We aim to settle the debate regarding the fraction of the Local Group's peculiar velocity that is induced by structures beyond the Great Attractor by calculating the dipole anisotropy of the largest, all-sky, truly X-ray-selected cluster sample compiled to date. The sample is the combination of the REFLEX catalog in the southern hemisphere, the eBCS sample in the north, and the CIZA survey in the Galactic plane. The composite REFLEX+eBCS+CIZA sample overcomes many of the problems inherent to previous galaxy and cluster catalogs that limited their effectiveness in determining the origin of the Local Group's motion. From the dipole anisotropy present in the cluster distribution, we determine that 44% of the Local Group's peculiar velocity is due to infall into the Great Attractor region, while 56% is in the form of a large-scale flow induced by more distant overdensities between 130 and 180 h-1 Mpc away. In agreement with previous analyses, we find that the Shapley supercluster is the single overdensity most responsible for the increase in the dipole amplitude beyond 130 h-1 Mpc, generating 30.4% of the large-scale contribution. We find that a significant portion of the remainder is due to numerous groupings and loose associations of clusters at roughly the same distance as the Shapley region. We also note the presence of a significant underdensity of clusters in the northern hemisphere roughly 150 h-1 Mpc away and suggest that the large-scale anisotropy observed in the cluster distribution near this distance may have as much to do with the presence of large overdensities in the south as it does with the lack of superclusters in the north.
A direct reduction of aliphatic aldehyde, acyl chloride, ester, and carboxylic functions into a methyl group.

The aliphatic carboxylic group was efficiently reduced to the methyl group by HSiEt3 in the presence of catalytic amounts of B(C6F5)3. To the best of our knowledge, this is the first example of a direct exhaustive reduction of aliphatic carboxylic function. Aliphatic aldehydes, acyl chlorides, anhydrides, and esters also underwent complete reduction under similar reaction conditions. Aromatic carboxylic acids, as well as other carbonyl functional equivalents, underwent smooth partial reduction to the corresponding TES-protected benzylic alcohols. It was shown that, unlike the reduction of aliphatic substrates, the exhaustive reduction of aromatic substrates was not straightforward: a concurrent Friedel−Crafts-like alkylation process competed with the reduction yielding trace to notable amounts of dimeric products, thus decreasing the overall selectivity of the reduction process.
Reply to ``Comment on `Negative temperature of vortex motion' ''

We respond to the questions raised in the preceding Comment [K. O'Neil and L. J. Campbell, Phys. Rev. A 47, 2966 (1993)]. We explain why our statement ``vortex temperature is always positive'' is equivalent to the ``opposite'' statement in the Comment: ``vortex temperature is always negative,'' and why we viewed the negative temperature states as paradoxical. We discuss also the notion of temperature for the limit case of infinite number of vortices.
Resolute: an assurance case language for architecture models

Arguments about the safety, security, and correctness of a complex system are often made in the form of an assurance case. An assurance case is a structured argument, often represented with a graphical interface, that presents and supports claims about a system's behavior. The argument may combine different kinds of evidence to justify its top level claim. While assurance cases deliver some level of guarantee of a system's correctness, they lack the rigor that proofs from formal methods typically provide. Furthermore, changes in the structure of a model during development may result in inconsistencies between a design and its assurance case. Our solution is a framework for automatically generating assurance cases based on 1) a system model specified in an architectural design language, 2) a set of logical rules expressed in a domain specific language that we have developed, and 3) the results of other formal analyses that have been run on the model. We argue that the rigor of these automatically generated assurance cases exceeds those of traditional assurance case arguments because of their more formal logical foundation and direct connection to the architectural model.
Using PLSI-U to detect insider threats by datamining e-mail

Despite a technology bias that focuses on external electronic threats, insiders pose the greatest threat to an organisation. This paper discusses an approach to assist investigators in identifying potential insider threats. We discern employees' interests from e-mail using an extended version of PLSI. These interests are transformed into implicit and explicit social network graphs, which are used to locate potential insiders by identifying individuals who feel alienated from the organisation or have a hidden interest in a sensitive topic. By applying this technique to the Enron e-mail corpus, a small number of employees appear as potential insider threats.
Connectivity graphs on two-dimensional surfaces and their application in robotics

The problem of robot motion planning in an environment with obstacles can often be reduced to the study of connectivity of the robot's free configuration space. In turn, space connectivity can be analysed via the corresponding connectivity graph. For two-degree-of-freedom robots, the free configuration space presents a two-dimensional (2D) surface—a compact subspace of a 2D orientable compact manifold. This paper addresses the following abstract problem: given a compact 2D surface bounded by simple closed curves and lying in an orientable 2D manifold (a sphere, a torus, etc.) and given two points in the subspace, suggest a systematic way of defining the connectivity graph in the subspace, based on its topological properties. The use of space topology results in powerful, from the robotics standpoint, provable algorithms capable of on-line motion planning in an environment with unknown obstacles of arbitrary shapes. This makes the method distinct from other techniques, which require complete information, algebraic representation of space geometry, and off-line computation.
Distributed lags and intermediate good imports

Abstract In this paper we draw upon some recent developments in the theory of dynamic economics and econometrics to characterize the time series behavior of intermediate good imports. It is shown that adjustment costs, delivery lags, and inventory holding costs considerations lead to distributed lag import demand functions that are not subject to the Nerlove (1972) and Lucas (1976) critiques of ad hoc and fixed distributed lag modelling.
Rational Design and Synthesis of a 1,1-Linked Disaccharide That Is 5 Times as Active as Sialyl Lewis X in Binding to E-Selectin

We describe here a rational design and synthesis of (3-O-carboxymethyl)-β-d-galactopyranosyl α-d-mannopyranoside which is 5 times as active as sialyl Lewis X in binding to E-selectin and also effective against P- and L-selectin. A new method for the 1,1-glycosidic bond formation via coupling of protected trimethylsilyl β-d-galactoside and α-mannosyl fluoride in the presence of BF3·Et2O is described.
BILINEAR ESTIMATES AND APPLICATIONS TO NONLINEAR WAVE EQUATIONS

We undertake a systematic review of results proved in [26, 27, 30-32] concerning local well-posedness of the Cauchy problem for certain systems of nonlinear wave equations, with minimal regularity assumptions on the initial data. Moreover we give a considerably simplified and unified treatment of these results and provide also complete proofs for large data. The paper is also intended as an introduction to and survey of current research in the very active area of nonlinear wave equations. The key ingredients throughout the survey are the use of the null structure of the equations we consider and, intimately tied to it, bilinear estimates.
Credit market imperfections and patterns of international trade and capital flows

This paper offers two simple models to illustrate how corporate governance, contractual enforcement, and the balance sheet condition of the business sector etc., can affect the patterns of international trade and capital flows in the presence of credit market imperfections. (JEL: D52, F15, F21, F40)
Aqueous Speciation Studies of Europium(III) Phosphotungstate

The incorporation of lanthanide ions into polyoxometalates may be a unique approach to generate new luminescent, magnetic, and catalytic functional materials. To realize these new applications of lanthanide polyoxometalates, it is imperative to understand the solution speciation chemistry and its impact on solid-state materials. In this study we find that the aqueous speciation of europium(III) and the trivacant polyoxometalate, PW9O349-, is a function of pH, countercation, and stoichiometry. For example, at low pH, the lacunary (PW11O39)7- predominates and the 1:1 Eu(PW11O39)4-, 2, forms. As the pH is increased, the 1:2 complex, Eu(PW11O39)211- species, 3, and (NH4)22{(Eu2PW10O38)4(W3O8(H2O)2(OH)4}·44H2O, a Eu8 hydroxo/oxo cluster, 1, form. Countercations modulate this effect; large countercations, such as K+ and Cs+, promote the formation of species 3 and 1. Addition of Al(III) as a counterion results in low pH and formation of {Eu(H2O)3(α-2-P2W17O61)}2, 4, with Al(III) counterions bound to terminal W−O...
Role of surface science in catalysis

Abstract Around the time of World War I, Langmuir advanced a simple theory of chemisorption and showed how it could be used to formulate rate laws for reactions occurring on surfaces. From that time on, surface science has played an important role in heterogeneous catalysis. Between the two world wars, simple studies of extents of adsorption by catalyst surfaces led to the concept of activated adsorption and to a universally used method for determining the high surface areas associated with the pore structures of catalytic materials. After World War II, the application of various spectroscopic and structural probes made it possible to investigate catalyst surfaces at a more microscopic level. Studies with idealized surfaces such as the faces of single crystals in ultra-high vacuum apparatus also made their appearance. By the end of the twentieth century, direct information was being obtained on the rates of elementary reactions of well-defined surface species. The results of such work are beginning to put “finishing touches” on the great insight of early pioneers in surface science and heterogeneous catalysis. Much has been accomplished, but exciting opportunities still remain.
A Polar and Chiral Indium Telluride Featuring Supertetrahedral T2 Clusters and Nonlinear Optical Second Harmonic Generation

The “KIn2” Zintl phase activates tellurium under solvothermal conditions and yields the compound {[In(en)3][In5Te9(en)2]·0.5en}n (en = ethylenediamine). The material has both a polar and chiral layered framework and exhibits type I phase-matchable strong second harmonic generation (SHG) response.
Measurements of segment size

Distributions of segment sizes measured under routine operating conditions on a computer system which utilizes variable sized segments (the Burroughs B5500) are discussed. The most striking feature of the measurements is the large number of small segments—about 60 percent of the segments in use contain less than 40 words. Although the results are certainly not installation independent, and although they are particularly influenced by features of the B5500 ALGOL system, they should be relevant to the design of new computer systems, especially with respect to the organization of paging schemes.
Linking team resources to work–family enrichment and satisfaction

Abstract Work–family scholars now recognize the potential positive effects of participation in one life domain (i.e., work or family) on performance in other life domains. We examined how employees might benefit from team resources, which are highly relevant to the modern workplace, in both work and nonwork domains via work–family enrichment. Using the Resource–Gain–Development model (Wayne, Grzywacz, Carlson, & Kacmar, 2007), we explored how team resources contribute to enrichment and resulting project and family satisfaction. Using multilevel structural equation modeling (ML-SEM) to analyze student data (N = 344) across multiple class projects, we demonstrated that individuals with team resources were more likely to experience both work-to-family and family-to-work enrichment. Further, enrichment mediated the relationship between team resources and satisfaction with the originating domain.
Binaries and the L Dwarf/T Dwarf Transition

High-resolution imaging has revealed an unusually high binary fraction among objects spanning the transition between the L dwarf and T dwarf spectral classes. In an attempt to reproduce and unravel the origins of this apparent binary excess, I present a series of Monte Carlo mass function and multiplicity simulations of field brown dwarfs in the vicinity of the Sun. These simulations are based on solar metallicity brown dwarf evolutionary models and incorporate empirical luminosity and absolute magnitude scales, measured multiplicity statistics, and observed spectral templates in the construction and classification of composite binary spectra. In addition to providing predictions for the number and surface density distributions of L and T dwarfs for volume-limited and magnitude-limited samples, these simulations successfully reproduce the observed binary fraction distribution assuming an intrinsic (resolved) binary fraction of 11% (95% confidence interval), consistent with prior determinations. However, the true binary fraction may be as high as 40% if, as suggested by Liu et al., a significant fraction of L/T transition objects (~66%) are tightly bound, unresolved multiples. The simulations presented here demonstrate that the binary excess among L/T transition objects arises primarily from the flattening of the luminosity scale over these spectral types and is not inherently the result of selection effects incurred in current magnitude-limited imaging samples. Indeed, the existence of a binary excess can be seen as further evidence that brown dwarfs traverse the L/T transition rapidly, possibly driven by a nonequilibrium submergence of photospheric condensates.
The Virtual Speech Community: Social Network and Language Variation on Irc

Many scholars anticipate that online interaction will have a long-term effect on the evolution of language, but little linguistic research yet addresses this question directly. In sociolinguistics, social network relations are recognized as the principal vehicle of language change. In this paper, I develop a social network approach to online language variation and change through qualitative and quantitative analysis of logfiles of Internet Relay Chat interaction. The analysis reveals a highly structured relationship between participants’ social positions on a channel and the linguistic variants they use. The emerging sociolinguistic relationship is more complex than what is predicted by current sociolinguistic theory for offline interaction, suggesting that sociolinguistic investigation of online interaction, where more detailed and fine-grained information about social contacts can be obtained, may offer unique contributions to the study of language variation and change.
Distributed stochastic optimization via correlated scheduling

This paper considers a problem where multiple devices make repeated decisions based on their own observed events. The events and decisions at each time-step determine the values of a utility function and a collection of penalty functions. The goal is to make distributed decisions over time to maximize time-average utility subject to time-average constraints on the penalties. An example is a collection of power-constrained sensors that repeatedly report their own observations to a fusion center. Maximum time-average utility is fundamentally reduced because devices do not know the events observed by others. Optimality is characterized for this distributed context. It is shown that optimality is achieved by correlating device decisions through a commonly known pseudo-random sequence. An optimal algorithm is developed that chooses pure strategies at each time-step based on a set of time-varying weights.
On the complexity of assembly partitioning

Abstract This paper studies the complexity of the assembly partitioning problem in the plane: given a collection of non-overlapping polygons, decide if there is a proper subcollection of them that can be removed as a rigid body without colliding with or disturbing the other parts of the assembly. It is shown that assembly partitioning is NP-complete. The result extends to several interesting variants of the problem.
Short-time diffusion in concentrated bidisperse hard-sphere suspensions

Diffusion in bidisperse Brownian hard-sphere suspensions is studied by Stokesian Dynamics (SD) computer simulations and a semi-analytical theoretical scheme for colloidal short-time dynamics, based on Beenakker and Mazur’s method [Physica A 120, 388–410 (1983); 126, 349–370 (1984)]. Two species of hard spheres are suspended in an overdamped viscous solvent that mediates the salient hydrodynamic interactions among all particles. In a comprehensive parameter scan that covers various packing fractions and suspension compositions, we employ numerically accurate SD simulations to compute the initial diffusive relaxation of density modulations at the Brownian time scale, quantified by the partial hydrodynamic functions. A revised version of Beenakker and Mazur’s δγ-scheme for monodisperse suspensions is found to exhibit surprisingly good accuracy, when simple rescaling laws are invoked in its application to mixtures. The so-modified δγ scheme predicts hydrodynamic functions in very good agreement with our SD simulation results, for all densities from the very dilute limit up to packing fractions as high as 40%.
EDP education: an acute crisis

According to a recent AFIPS study, the estimated number of unfilled openings for trained programmers in 1970 was between 200,000 and 650,000; and for systems analysts there were between 60,000 and 200,000 positions available. Industrial leaders are the first to admit that existing educational facilities are not adequate to supply the quantity and quality of training needed to fill the present market requirements---not to mention the steadily increasing demand foreseen for the future. From these observations it is obvious that the full potential of the computers presently in use cannot be realized because of the scarcity of sufficiently qualified programmers and analysts. As a consequence, many present-day computer installations are on the brink of chaos.
MATURITY STRUCTURE OF A HEDGE MATTERS: LESSONS FROM THE METALLGESELLSCHAFT DEBACLE

At the start of 1994 Metallgesellschaft AG, the 14th largest corporation in Germany, stood on the brink of bankruptcy as a result of more than $1 billion in losses from trading in oil futures. The futures trades were ostensibly a hedge for the firm's oil delivery contracts. How could a set of transactions which purportedly locked-in profits, making the firm safer, in fact lead the firm to bankruptcy? A critical problem was the mismatch in maturities between the company's delivery contract exposure to oil price risk and the company's portfolio of futures. Although the contract exposure was to long-term oil prices, it hedged with short- dated futures in order to capture profits from perceived mispricings in that market. When that gamble did not pay off, it undermined the entire company. Understanding the mistakes made by Metallgesellschaft is critical if other firms are to avoid a similar fate without forsaking the significant benefits available from a correctly planned hedging strategy.
Nonlinear vibrations of unsymmetrically laminated beams

The purpose of this study was to develop a simple one-dimensional finite element for the nonlinear analysis of symmetrically and unsymmetrically laminated composite beams including shear deformation. The beam element has 10 degrees of freedom at each of the two nodes: the axial displacement, the transverse deflection and the slope due to bending and shear, the twisting angle, the in-plane shear rotation, and their derivatives. The formulation, the solution procedure, and the computer program have been evaluated by solving a series of examples on the static response, free vibration, and nonlinear vibrations of isotropic and laminated beams. For unsymmetrically laminated beams, the nonlinear vibrations were found to have a soft spring behavior for certain boundary conditions as opposed to a hard spring behavior observed in isotropic and symmetrically laminated beams. The in-plane boundary conditions were found to have a significant effect on nonlinear responses.
Effects of substrate composition and roughness on mechanical properties and conformality of parylene C coatings

Nanoindentation was used to determine reduced elastic modulus Er and hardness H of 16 μm thick Parylene C coatings vapor-deposited on mill-finished samples of aluminum, copper, nickel steel, and stainless steel. Profilometry was used to compare average surface roughnesses of the polymeric coatings to the roughnesses of the underlying metals, thereby providing a quantitative index for determining conformality. Roughness, elasticity, and hardness of coatings were found to be affected by both chemical composition and surface roughness of four different metallic substrates. Standard nanoindentation evaluations of Er and H distributions for the various metals were found to be positively skewed, which precluded use of simple averages for purposes of comparison. However, analysis of the nanoindentation and profilometry data by use of alternative techniques indicated that coatings were consistently smoother and flatter than their underlying substrates, i.e., they were not truly conformal, and nanomechanical properties of Parylene C were affected by the chemical composition of the substrates independently of the effects of substrate roughness. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Self-consistent approximations in relativistic plasmas: Quasiparticle analysis of the thermodynamic properties

We generalize the concept of conserving, Φ-derivable, approximations to relativistic field theories. Treating the interaction field as a dynamical degree of freedom, we derive the thermodynamic potential in terms of fully dressed propagators, an approach which allows us to resolve the entropy of a relativistic plasma into contributions from its interacting elementary excitations. We illustrate the derivation for a hot relativistic system governed by electromagnetic interactions.
Evaluation of Dedekind sums, Eisenstein cocycles, and special values of L-functions

We define higher-dimensional Dedekind sums that generalize the classical Dedekind-Rademacher sums as well as Zagier's sums, and we show how to compute them effectively using a generalization of the continued-fraction algorithm. We present two applications. First, we show how to express special values of partial zeta functions associated to totally real number fields in terms of these sums via the Eisenstein cocycle introduced by R. Sczech. Hence we obtain a polynomial time algorithm for computing these special values. Second, we show how to use our techniques to compute certain special values of the Witten zeta function, and we compute some explicit examples.
Preference relation on fuzzy utilities based on fuzzy leftness relation on intervals

Abstract We define a new preference relation μ P ( x , y ) between two fuzzy numbers or utilities x and y , based on the fuzzy leftness relationship between intervals. A key property of μ P ( x , y ) is that it satisfies the well-known min-transitivity property: μ P ( x , z ) ⩾ min{( μ P ( x , y ), μ P ( y , z )}; the previous definitions of preference relation on fuzzy utilities satisfy only certain weaker forms of transitivity.
The Diffuse Gamma-Ray Background from Supernovae

The diffuse extragalactic ?-ray background in the MeV region is believed to be due to photons from radioactivity produced in supernovae throughout the history of galaxies in the universe. In particular, ?-ray line emission from the decay chain 56Ni?56Co?56Fe provides the dominant photon source (Clayton & Silk). Although iron synthesis occurs in all types of supernovae, the contribution to the background is dominated by Type Ia events due to their higher photon escape probabilities. Estimates of the star formation history in the universe suggest a rapid increase by a factor ~10 from the present to a redshift zp ~1.5, beyond which it either remains constant or decreases slowly. Little is known about the cosmological star formation history for redshift exceeding z ~5. We integrate the observed star formation history to determine the cosmic ?-ray background (CGB) from the corresponding supernova rate history. In addition to ?-rays from short-lived radioactivity in Type Ia supernovae (SN Ia's) and Type II, Ib, and Ic supernovae (SN II's, SN Ib's, SN Ic's) we also calculate the minor contributions from long-lived radioactivities (26Al, 44Ti, 60Co, and electron-positron pair annihilation). The time-integrated ?-ray spectrum of model W10HMM (Pinto & Woosley) was used as a template for Type II supernovae, and for SN Ia's we employ model W7 (Nomoto et al.). Although progenitor evolution for Type Ia supernovae is not yet fully understood, various arguments suggest delays of order 1-2 Gyr between star formation and the production of SN Ia's. The effect of this delay on the CGB is discussed. We emphasize the value of ?-ray observations of the CGB in the MeV range as an independent tool for studies of the cosmic star formation history. If the delay between star formation and SN Ia activity exceeds 1 Gyr substantially and/or the peak of the cosmic star formation rate occurs at a redshift much larger than unity, the ?-ray production of SN Ia's would be insufficient to explain the observed CGB and a so far undiscovered source population would be implied. Alternatively, the cosmic star formation rate would have to be higher (by a factor 2-3) than commonly assumed, which is in accord with several upward revisions reported in the recent literature.
Decision making in the ageing brain: changes in affective and motivational circuits

Ageing affects multiple aspects of brain structure and function, and therefore is likely to influence complex behaviours such as decision making. Samanez-Larkin and Knutson describe age-related changes in the affective and motivational circuits that drive choice, and consider how these influence decision making.
Mesoscopic effects in the quantum Hall regime

We report results of a study of (integer) quantum Hall transitions in a single or multiple Landau levels for non-interacting electrons in disordered two-dimensional systems, obtained by projecting a tight-binding Hamiltonian to the corresponding magnetic subbands. In finite-size systems, we find that mesoscopic effects often dominate, leading to apparent non-universal scaling behavior in higher Landau levels. This is because localization length, which grows exponentially with Landau level index, exceeds the system sizes amenable to the numerical study at present. When band mixing between multiple Landau levels is present, mesoscopic effects cause a crossover from a sequence of quantum Hall transitions for weak disorder to classical behavior for strong disorder. This behavior may be of relevance to experimentally observed transitions between quantum Hall states and the insulating phase at low magnetic fields.
Total synthesis of (+)-complanadine A using an iridium-catalyzed pyridine C-H functionalization.

The total synthesis of the Lycopodium alkaloid complanadine A, which is an unsymmetrical dimer of lycodine, was achieved by exploiting a common tetracyclic precursor. Key to the success of the synthesis was the development of a late-stage site-selective C−H functionalization of a pyridine moiety to arrive at a key boronic ester intermediate.
Topological hole detection in wireless sensor networks and its applications

The identification of holes in a wireless sensor network is of primary interest since the breakdown of sensor nodes in a larger area often indicates one of the special events to be monitored by the network in the first place (e.g. outbreak of a fire, destruction by an earthquakes etc.). This task of identifying holes is especially challenging since typical wireless sensor networks consist of lightweight, low-capability nodes that are unaware of their geographic location.But there is also a secondary interest in detecting holes in a network: recently routing schemes have been proposed that do not assume knowledge of the geographic location of the network nodes but rather perform routing decisions based on the topology of the communication graph. Holes are salient features of the topology of a communication graph.In the first part of this paper we propose a simple distributed procedure to identify nodes near the boundary of the sensor field as well as near hole boundaries. Our hole detection algorithm is based purely on the topology of the communication graph, i.e. the only information available is which nodes can communicate with each other. In the second part of this paper we illustrate the secondary interest of our hole detection procedure using several examples.
Balanced complexes and complexes without large missing faces

The face numbers of simplicial complexes without missing faces of dimension larger than i are studied. It is shown that among all such (d−1)-dimensional complexes with non-vanishing top homology, a certain polytopal sphere has the componentwise minimal f-vector; and moreover, among all such 2-Cohen–Macaulay (2-CM) complexes, the same sphere has the componentwise minimal h-vector. It is also verified that the l-skeleton of a flag (d−1)-dimensional 2-CM complex is 2(d−l)-CM, while the l-skeleton of a flag piecewise linear (d−1)-sphere is 2(d−l)-homotopy CM. In addition, tight lower bounds on the face numbers of 2-CM balanced complexes in terms of their dimension and the number of vertices are established.
Synthesis and biological activity of a series of 4-aryl substituted benz[b]azepines: Antagonists at the strychnine-insensitive glycine site

Abstract A series of 4-arylbenz[b]azepine analogs were prepared and shown to act as antagonists at the strychnine-insensitive glycine receptor. The heteroaryl substituted benz[b]azepine derivative 11 also showed excellent in vivo activity.
A Complementary Ecological Model of the Coordinated School Health Program

BACKGROUND: A complementary ecological model of the coordinated school health program (CSHP) reflecting 20 years of evolved changes is proposed. Ecology refers to the complex interrelationship between intrapersonal factors, interpersonal processes and primary groups, institutional factors, community factors, and public policy. METHODS: Public health and child development theories that incorporate the influence of personal and social environments on health behavior, along with models that incorporate the influence of ecology, were consulted. RESULTS: Concepts from several models were combined with the 8 components of CSHP to formulate an ecological model involving 6 program and services components in an inner circle surrounded by 4 concentric rings representing the healthy school environment, essential structures of CSHP, local school district governance, and family and community involvement. CONCLUSION: This complementary ecological model is intended to serve as an additional conceptual approach to CSHP practice, evaluation, and research, and should prove especially useful to practitioners and researchers who already have a fundamental understanding of CSHP.