cssi/SciSciGPT-SciSciNet huggingface dataset:
Determinants and Consequences of Firm Information Technology Budgets

ABSTRACT: For most firms, the information technology (IT) budget represents a major element in the overall firm budget, and IT budget decisions often have significant operational and strategic impacts on the business processes in the firm’s value chain. In this paper we use a large unique data set to examine the extent to which IT budgets are affected by environmental, organizational, and technological circumstances. We find that our cross-sectional model explains substantial variance in IT budgets, which indicates that contingent environmental, organizational, and technological factors affect managers’ budget decisions. We then examine the extent to which these IT budget levels are related to future firm performance, measured using both broad financial accounting measures, such as operating profit margins and return on assets, and market returns. We find that IT budget levels are positively associated with subsequent firm performance and shareholder returns. We further suggest that IT’s aggregate effect ...
An Ontological Architecture for Orbital Debris Data

The orbital debris problem presents an opportunity for international cooperation toward the mutually beneficial goals of orbital debris prevention, mitigation, remediation, and improved space situational awareness (SSA). Achieving these goals requires sharing orbital debris and other SSA data. Toward this, I present an ontological architecture for the orbital debris and related domains, taking steps in the creation of an orbital debris ontology. The purpose of the ontology is to capture general scientific domain knowledge; formally represent the entities within the domain; form, structure, and standardize (where needed) orbital and SSA terminology; and foster semantic interoperability and data-exchange. In doing so I hope to offer a scientifically accurate ontological representation of the orbital domain; contribute to research in astroinformatics, space ontology, and space data management; and improve spaceflight safety by providing a means to capture and communicate informaiton associated with space debris.
Highly Diastereoselective and Enantioselective Preparation of Homoallylic Amines: Application for the Synthesis of β‐Amino Acids and γ‐Lactams

Reactions of N-silyl- and N-aluminoimines with B-allyldiisopinocampheylborane in the presence of methanol, followed by oxidative workup furnished homoallylic amines in good yields and high ee. A 11B NMR spectroscopy study revealed that the reactions do not proceed, even at room temperature, unless a molar equivalent of water or methanol is added. The first reagent-controlled asymmetric crotylboration and alkoxyallylboration of aldimines furnishing beta-methyl or beta-alkoxy homoallylic amines in very high diastereoselectivity and enantioselectivity are reported herein. Crotylboration and alkoxyallylboration of imines proceed only with the "allyl"-boron "ate" complexes, instead of the "allyl"-dialkylboron reagents used with aldehydes. The addition of methanol is necessary for these reactions as well. Application of this methodology for the conversion of representative nitriles to beta-amino acids in two steps has been described. Additionally, a procedure for the preparation of chiral delta-amino alcohols and gamma-lactams from nitriles is also reported.
End-to-end routing behavior in the Internet

The large-scale behavior of routing In the Internet has gone virtually without any formal study, the exceptions being Chinoy's (1993) analysis of the dynamics of Internet routing information, and work, similar in spirit, by Labovitz, Malan, and Jahanian (see Proc. SIGCOMM'97, 1997). We report on an analysis of 40000 end-to-end route measurements conducted using repeated "traceroutes" between 37 Internet sites. We analyze the routing behavior for pathological conditions, routing stability, and routing symmetry. For pathologies, we characterize the prevalence of routing loops, erroneous routing, infrastructure failures, and temporary outages. We find that the likelihood of encountering a major routing pathology more than doubled between the end of 1994 and the end of 1995, rising from 1.5% to 3.3%. For routing stability, we define two separate types of stability, "prevalence", meaning the overall likelihood that a particular route is encountered, and "persistence", the likelihood that a route remains unchanged over a long period of time. We find that Internet paths are heavily dominated by a single prevalent route, but that the time periods over which routes persist show wide variation, ranging from seconds up to days. About two-thirds of the Internet paths had routes persisting for either days or weeks. For routing symmetry, we look at the likelihood that a path through the Internet visits at least one different city in the two directions. At the end of 1995, this was the case half the time, and at least one different autonomous system was visited 30% of the time.
On multilinear determinant functionals

This paper considers the problem of L p -estimates for a certain multilinear functional involving integration against a kernel with the structure of a determinant. Examples of such objects are ubiquitous in the study of Fourier restriction and geometric averaging operators. It is shown that, under very general circumstances, the boundedness of such functionals is equivalent to a geometric inequality for measures which has recently appeared in work by D. Oberlin and by Bak, Oberlin, and Seeger.
Jet tomography of quark gluon plasma

Recent experimental measurements of high pT hadron spectra and jet correlation at RHIC are analyzed within a parton model which incoporates initial jet production and final propagation in heavy-ion collisions. The suppre-sion of single hadron spectra, back-to-back correlation, their centrality dependence and azimuthal anisotropy point to a dense matter with an initial parton density about 30 times of that in a cold heavy nucleus.
Resolving exceptional configurations

In lattice QCD with Wilson fermions, exceptional configurations arise in the quenched approximation at small quark mass. The origin of these large previously uncontrolled lattice artifacts is identified. A simple well-defined procedure (MQA) is presented which removes the artifacts while preserving the correct continuum limit.
Who Should Buy Long-Term Bonds?

According to conventional wisdom, long-term bonds are appropriate for conservative long-term investors. This paper develops a model of optimal consumption and portfolio choice for infinite-lived investors with recursive utility who face stochastic interest rates, solves the model using an approximate analytical method, and evaluates conventional wisdom. As risk aversion increases, the myopic component of risky asset demand disappears but the intertemporal hedging component does not. Conservative investors hold assets to hedge the risk that real interest rates will decline. Long-term inflation-indexed bonds are most suitable for this purpose, but nominal bonds may also be used if inflation risk is low.
Irreducible representations of finite spin groups

We perform the computations necessary to establish a multiplicity one statement for the irreducible representations of a finite spin group which in turn yields the classification of irreducible representations of finite spin groups. (The multiplicity one statement was previously stated without proof.)
EXPERIMENTS IN MULTIVARIABLE ADAPTIVE CONTROL OF A LARGE FLEXIBLE STRUCTURE

A six-input/six-output multivariable adaptive controller is used to control a large 3-dimensional flexible structure experiment. For this purpose, the JPLIAFAL antennalike experiment structure is used, with instrumentation distributed on both the hub and the ribs. This represents a significant increase in complexity relative to earlier adaptive control experiments performed on the same structure, utilizing a two-input/two-output set-up with instrumentation on the hub alone [I]. The increase in instrumentation significantly increases spatial controllability, and excitation and control of a much larger set of modes. This paper documents multivariable adaptive control experiments on this structural configuration, and discusses many of the associated design and implementation issues required for successful operation.
Three-level Stackelberg decision problems

Three-level Stackelberg decision problems are studied by using the inducible region concept. Through a systematic derivation, it is identified that the leader's control has dual purposes, which in general are not separable. A special class of problems is then considered, where explicit results are obtained.
On the cohomology of Young modules for the symmetric group

Abstract The main result of this paper is an application of the topology of the space Q ( X ) to obtain results for the cohomology of the symmetric group on d letters, Σ d , with ‘twisted’ coefficients in various choices of Young modules and to show that these computations reduce to certain natural questions in representation theory. The authors extend classical methods for analyzing the homology of certain spaces Q ( X ) with mod-p coefficients to describe the homology H • ( Σ d , V ⊗ d ) as a module for the general linear group GL ( V ) over an algebraically closed field k of characteristic p. As a direct application, these results provide a method of reducing the computation of Ext Σ d • ( Y λ , Y μ ) (where Y λ , Y μ are Young modules) to a representation theoretic problem involving the determination of tensor products and decomposition numbers. In particular, in characteristic two, for many d, a complete determination of H • ( Σ d Y λ ) can be found. This is the first nontrivial class of symmetric group modules where a complete description of the cohomology in all degrees can be given. For arbitrary d the authors determine H i ( Σ d , Y λ ) for i = 0 , 1 , 2 . An interesting phenomenon is uncovered-namely a stability result reminiscent of generic cohomology for algebraic groups. For each i the cohomology H i ( Σ p a d , Y p a λ ) stabilizes as a increases. The methods in this paper are also powerful enough to determine, for any p and λ, precisely when H • ( Σ d , Y λ ) = 0 . Such modules with vanishing cohomology are of great interest in representation theory because their support varieties constitute the representation theoretic nucleus.
Stochastic Gradient Hamiltonian Monte Carlo

Hamiltonian Monte Carlo (HMC) sampling methods provide a mechanism for defining distant proposals with high acceptance probabilities in a Metropolis-Hastings framework, enabling more efficient exploration of the state space than standard random-walk proposals. The popularity of such methods has grown significantly in recent years. However, a limitation of HMC methods is the required gradient computation for simulation of the Hamiltonian dynamical system--such computation is infeasible in problems involving a large sample size or streaming data. Instead, we must rely on a noisy gradient estimate computed from a subset of the data. In this paper, we explore the properties of such a stochastic gradient HMC approach. Surprisingly, the natural implementation of the stochastic approximation can be arbitrarily bad. To address this problem we introduce a variant that uses second-order Langevin dynamics with a friction term that counteracts the effects of the noisy gradient, maintaining the desired target distribution as the invariant distribution. Results on simulated data validate our theory. We also provide an application of our methods to a classification task using neural networks and to online Bayesian matrix factorization.
Highly Efficient Synthesis of Chiral β-Amino Acid Derivatives via Asymmetric Hydrogenation

The Rh−TangPhos complex is an efficient hydrogenation catalyst for making chiral β-amino acid derivatives. With the Rh−TangPhos system, high enantioselectivities (up to 99.6%) and turnover numbers have been obtained in the hydrogenation of E/Z isomeric mixtures of both β-alkyl and β-aryl β-(acylamino)acrylates.
Two Oil Types on the North Slope of Alaska. Implications for Future Exploration

Forty oil samples from across the North Slope of Alaska have been analyzed by the US Bureau of Mines and the Us Geological Survey. Results of these analyses suggest two separate genetic oil types. The first type, the Simpson-Umiat oil type, occurs in reservoir rocks of Cretaceous and Quaternary age and includes oils from seeps in the Skull Cliff, Cape Simpson, Manning Point, and Ungoon Point areas; the Wolf Creek test well 3, and the Umiat oil field. These are higher gravity, low-sulfur oils with no, or slight, odd-numbered n-alkane predominance and pristane to phytane ratios greater than 1. 5. The second type, the Barrow-Prudhoe oil type, occurs in reservoir rocks of Carboniferous to Cretataceous age and includes ails from South Barrow gas field, Prudhoe Bay oil field, and the Fish Creek test well 1. Physical properties of Barrow-Prudhoe oils are variable, but in general the oils are medium-gravity, high-sulfur oils with a slight even-numbered n-alkane predominance and pristane to phytane ratio of less thon 1. 5. The two types are believed to originated from different source rocks; the Barrow-Prudhoe type may have originated from a carbonate or other iron-deficient source rock, and the Simpson-Umiat type from asiliciclastic source rock. Occurrences of fine two oil types, when outlined on a map, indicate atleast two exploration fairways. The fairway for the Barrow-Prudhoe type is along the Barrow arch, and the fairway, for the Simpson-Umiat type is the area of the best reservoir development for the Nanushuk Group.
Greener and expeditious synthesis of bioactive heterocycles using microwave irradiation

The utilization of green chemistry techniques is dramatically reducing chemical waste and reaction times as has recently been proven in several organic syntheses and chem- ical transformations. To illustrate these advantages in the synthesis of bioactive heterocycles, we have studied various environmentally benign protocols that involve greener alternatives. Microwave (MW) irradiation of neat reactants catalyzed by the surfaces of recyclable min- eral supports, such as alumina, silica, clay, or their "doped" versions, enables the rapid one- pot assembly of heterocyclic compounds, such as flavonoids, related benzopyrans, and quinolone derivatives. The strategy to assemble oxygen and nitrogen heterocycles from in situ generated reactive intermediates via enamines or using hypervalent iodine reagents is de- scribed. Examples of multicomponent reactions that can be adapted for rapid parallel syn- thesis include solventless synthesis of dihydropyrimidine-2(1H)-ones (Biginelli reaction), imidazo(1,2-a)annulated pyridines, pyrazines, and pyrimidines (Ugi reaction). The relative advantages of greener pathways, which use MW irradiation and eco-friendly aqueous reac- tion medium, for the synthesis of various heterocycles, such as N-aryl azacycloalkanes, isoindoles, 1,3-dioxane, 1,3,4-oxadiazole, 1,3,4-thiadiazole, pyrazole, and diazepines, are also summarized.
Turbulent Boundary-Layer Separation due to a Forward-Facing Step

Pressure distribution tests were made at Mach numbers of 1.61 and 2.20, over a step-height range from 0.005 to 2.54 cm, and an effective length Reynolds number range from about 8 to 150 million. The results were compared with some obtained at higher Mach numbers at approximately comparable boundary-layer conditions. The comparison showed several unexplainable anomalies, and pointed up the lack of boundary-laye r information necessary for a proper analysis. An analysis of the data indicates the existence of a transverse vortex in the separated-flow region which weakens with increases in Reynolds and Mach number and significantly affects the pressure distributions.
The Role of Virtual Communities of Practice in Supporting Collaborative Learning among Social Workers

The advent of technology has been instrumental in creating access for social workers to research on evidence-based interventions. However, for many social problems there remains a gap in the availability of proven evidence-based strategies (Rosen et al., 1999). For social workers facing problems for which there is a lack of research evidence, the solution is to develop practice innovations that can be evaluated (Sabah and Cook-Craig, 2008a, b). Virtual communities of practice (VCoP's) are a promising venue for housing reviews of research evidence and engaging social workers to share tacit knowledge and invent practice innovations. During the past two years, the Israeli Ministry of Social Affairs has developed eighteen VCoP's social work practitioners. Those communities are designed to enable practitioners to review and use multiple sources of professional relevant knowledge in user-friendly repositories and to facilitate a collaborative inter-organizational learning and innovativeness. This exploratory study reviews evaluation data collected on the VCoP's. It includes quantitative analysis of secondary data and survey data on usage patterns of VCoP members. Findings related VCoP usage, the impact that organizational endorsement of organizational learning has on worker involvement in the community, and the development of weak professional ties between members were evaluated.
Prevalent Behavior of Strongly Order Preserving Semiflows

Classical results in the theory of monotone semiflows give sufficient conditions for the generic solution to converge toward an equilibrium or toward the set of equilibria (quasiconvergence). In this paper, we provide new formulations of these results in terms of the measure-theoretic notion of prevalence, developed in Christensen (Israel J. Math., 13, 255–260, 1972) and Hunt et al. (Bull. Am. Math. Soc., 27, 217–238, 1992). For monotone reaction–diffusion systems with Neumann boundary conditions on convex domains, we show the prevalence of the set of continuous initial conditions corresponding to solutions that converge to a spatially homogeneous equilibrium. We also extend a previous generic convergence result to allow its use on Sobolev spaces. Careful attention is given to the measurability of the various sets involved.
An Economically-Principled Generative Model of AS Graph Connectivity

End-to-end packet delivery in the Internet is achieved through a system of interconnections between the network domains of independent entities called Autonomous Systems (ASes). Inter-domain connections are the result of a complex, dynamic process of negotiated business relationships between pairs of ASes. We present an economically-principled generative model for Autonomous System graph connectivity. While there is already a large literature devoted to understanding Internet connectivity at the AS level, many of these models are either static or based on generalized stochastics. In a thoughtful critique of such models, Li, Alderson, Doyle and Willinger [10] show that while many generative models reproduce certain statistical features of the AS graph, they fail to capture the good performance of realistic networks [10]. In a study of the AS’s intra-domain graph, Li, Alderson, Willinger and Doyle [11] define performance instead in terms of network throughput and show that it is very unlikely that randomized generative models will yield graphs that have the highly-optimized structure of real-world networks. The goal of this paper is to provide insight into the economic drivers that yield, over time, the rich and complex AS interconnection patterns that constitute today’s Internet. Notable features of our model include the assignment of AS business models with an asymmetric gravity model of interdomain traffic demand [3], an explicit representation of AS utility that incorporates benefits for traffic routed, congestion costs, and payments between ASes, and a deterministic process for link revision that can cascade throughout the network. This is the first attempt at AS graph modeling that incorporates a diffusion process to capture how ASes respond to direct and indirect externalities from changes in the network structure, which brings it closer to an equilibrium model. We validate our model against other generative models. To do this, we define the social planner’s problem which is parameterized by the business models of the graph and provide a method to compare earlier generative models with our model by optimizing the placement of business models on the network. We find that our model yields graphs that are better performing as compared to other dynamic generative models. We also show that our model yields a structured placement of nodes endogenously, where this placement of nodes generally reflects ASes’ business models. This is some of the first evidence of the significance of the business competitive landscape in determining the structure of the AS graph.
Discovering non-coding RNA elements in Drosophila 3' untranslated regions

The Non-Coding RNA ncRNA elements in the 3' Untranslated Regions 3'-UTRs are known to participate in the genes' post-transcriptional regulations. Inferring co-expression patterns of the genes through clustering these 3'-UTR ncRNA elements will provide invaluable insights for studying their biological functions. In this paper, we propose an improved RNA structural clustering pipeline. Benchmark of the new pipeline on Rfam data demonstrates over 10% performance improvements compared to the traditional hierarchical clustering pipeline. By applying the new clustering pipeline to 3'-UTRs of Drosophila melanogaster's genome, we have successfully identified 184 ncRNA clusters with 91.3% accuracy. One of these clusters corresponds to genes that are preferentially expressed in male Drosophila. Another cluster contains genes that are responsible for the functions of septate junction in epithelial cells. These discoveries encourage more studies on novel post-transcriptional regulation mechanisms.
Constraining type II 2HDM in light of LHC Higgs searches

We study the implication of the LHC Higgs search results on the Type II Two Higgs-Doublet Model. In particular, we explore the scenarios in which the observed 126 GeV Higgs signal is interpreted as either the light CP-even Higgs h 0 or the heavy CP-even Higgs H 0. Imposing both theoretical and experimental constraints, we analyze the surviving parameter regions in m H (m h ), m A , m H ±, tan β and sin(β − α). We further identify the regions that could accommodate a 126 GeV Higgs with cross sections consistent with the observed Higgs signal. We find that in the h 0-126 case, we are restricted to narrow regions of sin(β − α) ≈ ±1 with tan β up to 4, or an extended region with 0.55 < sin(β − α) < 0.9 and 1.5 < tan β < 4. The values of m H , m A and m H ±, however, are relatively unconstrained. In the H 0-126 case, we are restricted to a narrow region of sin(β − α) ~ 0 with tan β up to about 8, or an extended region of sin(β − α) between −0.8 to −0.05, with tan β extended to 30 or higher. m A and m H ± are nearly degenerate due to Δρ constraints. Imposing flavor constraints shrinks the surviving parameter space significantly for the H 0-126 case, limiting tan β ≲ 10, but has little effect in the h 0-126 case. We also investigate the correlation between γγ, V V and bb/ττ channels. γγ and V V channels are most likely to be highly correlated with γγ: V V ~ 1 for the normalized cross sections.
The effects of cues on neurons in the basal ganglia in Parkinson's disease.

Visual cues open a unique window to the understanding of Parkinson's disease (PD). These cues can temporarily but dramatically improve PD motor symptoms. Although details are unclear, cues are believed to suppress pathological basal ganglia (BG) activity through activation of corticostriatal pathways. In this study, we investigated human BG neurophysiology under different cued conditions. We evaluated bursting, 10–30 Hz oscillations (OSCs), and directional tuning (DT) dynamics in the subthalamic nucleus (STN) activity while seven patients executed a two-step motor task. In the first step (predicted +cue), the patient moved to a target when prompted by a visual go cue that appeared 100% of the time. Here, the timing of the cue is predictable and the cue serves an external trigger to execute a motor plan. In the second step, the cue appeared randomly 50% of the time, and the patient had to move to the same target as in the first step. When it appeared (unpredicted +cue), the motor plan was to be triggered by the cue, but its timing was not predictable. When the cue failed to appear (unpredicted −cue), the motor plan was triggered by the absence of the visual cue. We found that during predicted +cue and unpredicted −cue trials, OSCs significantly decreased and DT significantly increased above baseline, though these modulations occurred an average of 640 ms later in unpredicted −cue trials. Movement and reaction times were comparable in these trials. During unpredicted +cue trials, OSCs, and DT failed to modulate though bursting significantly decreased after movement. Correspondingly, movement performance deteriorated. These findings suggest that during motor planning either a predictably timed external cue or an internally generated cue (generated by the absence of a cue) trigger the execution of a motor plan in premotor cortex, whose increased activation then suppresses pathological activity in STN through direct pathways, leading to motor facilitation in PD.
Mathematical modeling of tumor therapy with oncolytic viruses: effects of parametric heterogeneity on cell dynamics

Background: One of the mechanisms that ensure cancer robustness is tumor heterogeneity, and its effects on tumor cells dynamics have to be taken into account when studying cancer progression. There is no unifying theoretical framework in mathematical modeling of carcinogenesis that would account for parametric heterogeneity.
Early growth and coronary heart disease and type 2 diabetes: findings from the Helsinki Birth Cohort Study (HBCS)

A slow rate of intrauterine growth is a major risk factor for several common noncommunicable diseases, which include the following: coronary heart disease (CHD), hypertension, and type 2 diabetes. Likewise, growth patterns in infancy and childhood have been identified as important factors linked to the pathogenesis of these disorders. In this overview, patterns of growth associated with CHD, type 2 diabetes, and related metabolic traits in adult life are presented on the basis of findings from the Helsinki Birth Cohort Study (HBCS) 1934-1944. Later risk of CHD was associated with small body size at birth and during infancy, followed by an increase in body size later in childhood. This pattern of growth has been associated with dyslipidemia in later life, which offers an explanation for the observed findings. Type 2 diabetes and CHD share several risk factors. The early growth of persons who later develop type 2 diabetes includes a small body size at birth as well as a small body size during infancy. An early age at adiposity rebound was associated with a markedly increased risk of type 2 diabetes in adulthood. The patterns of growth associated with type 2 diabetes are also associated with alterations in body composition, which predisposes to insulin resistance and the metabolic syndrome. The presented findings suggest that to be able to understand the pathogenesis of several noncommunicable diseases, the diseases need to be studied from a life-course perspective, and prenatal and childhood growth as well as adult characteristics need to be taken into account.
Reactions of GaX3 (X = BR, I) with As(SiMe3)3; Crystal Structures of I3Ga.As(SiMe3)3 and (I2GaAs(SiMe3)2)2

Reactions of GaX3 (X Br, I) with As(SiMe3)3 in 1:1 and 2:1 mole ratios were investigated. For the latter reactant stoichiometry, substances having the empirical formulae AsBr3Ga2 (1) and Asl3Ga2 (2), the analogues of the previously reported single-source GaAs precursor (AsCl3Ga2)n, were isolated as yellow isolated as yellow insoluble powders. Low-temperature reactions in a 1:1 mole ratio resulted in the isolation of the adducts Br3Ga.As(SiMe3)3 (3) and I3Ga.As(SiMe3)3 (4). On the other hand, at room temperature the GaBr3 reaction resulted in a complex mixture from which no characterizable compounds were isolated, whereas the Gal3 reaction afforded the crystalline compound [I2GaAs(SiMe3)2]2 (5). The structures of 4 and 5 were elucidated by complete single-crystal X-ray analysis (crystal data: 4, monoclinic, space group P21/c, a = 16.497(2) A, b = 9.629(1) A, c = 16.658(2) A, β = 113.21(1)°, V = 2432(1) A3, Z = 4; 5, orthorhombic, space group Pbca, a = 14.279(2) A, b = 17.509(2) A, c = 13.818(2), A, V = 3455(1) A3, Z = 4).
The Nevai Condition

We study Nevai’s condition that for orthogonal polynomials on the real line, K_n(x, x_0)^2K_n(x_0, x_0) ^(−1) dρ(x) → δ_(x0), where K_n is the Christoffel–Darboux kernel. We prove that it holds for the Nevai class of a finite gap set uniformly on the spectrum, and we provide an example of a regular measure on [−2, 2] where it fails on an interval.
On injective homomorphisms for pure braid groups, and associated Lie algebras

Abstract The purpose of this article is to record the center of the Lie algebra obtained from the descending central series of Artin's pure braid group, a Lie algebra analyzed in work of Kohno [T. Kohno, Linear representations of braid groups and classical Yang–Baxter equations, in: Contemp. Math., vol. 78, 1988, pp. 339–363; T. Kohno, Vassiliev invariants and the de Rham complex on the space of knots, in: Symplectic Geometry and Quantization, in: Contemp. Math., vol. 179, Amer. Math. Soc., Providence, RI, 1994, pp. 123–138; T. Kohno, Serie de Poincare–Koszul associee aux groupes de tresses pures, Invent. Math. 82 (1985) 57–75], and Falk and Randell [M. Falk, R. Randell, The lower central series of a fiber-type arrangement, Invent. Math. 82 (1985) 77–88]. The structure of this center gives a Lie algebraic criterion for testing whether a homomorphism out of the classical pure braid group is faithful which is analogous to a criterion used to test whether certain morphisms out of free groups are faithful [F.R. Cohen, J. Wu, On braid groups, free groups, and the loop space of the 2-sphere, in: Algebraic Topology: Categorical Decomposition Techniques, in: Progr. Math., vol. 215, Birkhauser, Basel, 2003; Braid groups, free groups, and the loop space of the 2-sphere, math.AT/0409307 ]. However, it is as unclear whether this criterion for faithfulness can be applied to any open cases concerning representations of P n such as the Gassner representation.
Load transfer along the bone-dental implant interface

In this paper the variation of normal and shear stresses along a path defined on the bone-dental implant interface is investigated. In particular, the effects of implant diameter, collar length and slope, body length, and the effects of four different types of external threads on the interfacial stress distribution are studied. The geometry of the bone is digitized from a CT scan of a mandibular incisor and the surrounding bone. The bone and the implant are assumed to be perfectly bonded. The finite element method with 2D plane strain assumption is used to compute interfacial stresses. Highest continuous interfacial stresses are encountered in the region where the implant collar engages the cortical region, and near the apex of the implant in the subcortical region. Stress concentrations in the interfacial stresses occur near the geometric discontinuities on the implant contour, and jumps in stress values occur where the elastic modulus of the bone transitions between the cortical and trabecular bone values. Among the six contour parameters, the slope and the length of the implant collar, and the implant diameter influence the interfacial stress levels the most, and the effects of changing these parameters are significantly noticed only in the cortical bone (alveolar ridge) area. External threads cause significant stress concentrations in interfacial stresses in otherwise smoothly varying regions. This work shows that the presence of external threads could cause significant variations in both normal and shear stresses along the bone-implant interface, but not reduction in shear stress as previously thought.
Some exact results on the matter star-product in the half-string formalism

We show that the D25 sliver wavefunction, just as the D-instanton sliver, factorizes when expressed in terms of half-string coordinates. We also calculate analytically the star-product of two zero-momentum eigenstates of using the vertex in the oscillator basis, thereby showing that the star-product in the matter sector can indeed be seen as multiplication of matrices acting on the space of functionals of half strings. We then use the above results to establish that the matrices ?1,2, conjectured by Rastelli, Sen and Zwiebach to be left and right projectors on the sliver, are indeed so.
The growth and applications of silicides for nanoscale devices

Metal silicides have been used in silicon technology as contacts to achieve high device performance and desired device functions. The growth and applications of silicide materials have recently attracted increasing interest for nanoscale device applications. Nanoscale silicide materials have been demonstrated with various synthetic approaches. Solid state reaction wherein high quality silicides form through diffusion of metal atoms into silicon nano-templates and the subsequent phase transformation caught significant attention for the fabrication of nanoscale Si devices. Very interestingly, studies on the diffusion and phase transformation processes at the nanoscale have indicated possible deviations from the bulk and the thin film system. Here we present a review of fabrication, growth kinetics, electronic properties and device applications of nanoscale silicides formed through solid state reaction.
New catalysts and methods for highly enantioselective metal carbene reactions

Asymmetric catalysis of metal carbene transformations with unique chiral dirhodium(I1) carboxamidates provides highly enantioselective, diastereoselective, and regioselective syntheses of lactones and lactams via cyclopropanation, cyclopropenation, carbon-hydrogen insertion, and ylide derived reactions of diazo acetates and diazoacetamides. Constructed from a dirhodium(I1) core with bridging chiral pyrrolidone, oxazolidinone, azedinone, or imidazolidinone ligands, these catalysts are especially effective for intramolecular transformations. Reactions characteristically occur with high turnover numbers, and products are formed in high yield with enantiomeric excesses that are generally greater than 90%.
The Planetary Nebula Luminosity Function

The (O III) λ5007 planetary nebula luminosity function (PNLF) occupies an important place on the extragalactic distance ladder: it is the only standard candle that can be applied to all the large galaxies of the Local Supercluster. We review the method's precision, and use it to show that the distance scale defined by Cepheids and the Surface Brightness Fluctuation method is likely too large by ∼ 7%. We also discuss some of the physics underlying the phenomenon, and present clues as why the technique is so resilient.
Marketing of Cotton Fiber in the Presence of Yield and Price Risk

An expected-utility model and a chance-constrained linear programming model were used to analyze four marketing strategies and seven crop insurance alternatives for cotton marketing in Georgia. The results suggest that existing marketing tools and insurance alternatives can be used to reduce cotton producers’ revenue risk. The optimal level of yield and price insurance coverage depends on an individual producer’s risk aversion.
Obscuration of Flare Emission by an Eruptive Prominence

We report on the eclipsing of microwave flare emission by an eruptive prominence from a neighboring region as observed by the Nobeyama Radioheliograph at 17 GHz. The obscuration of the flare emission appears as a dimming feature in the microwave flare light curve. We use the dimming feature to derive the temperature of the prominence and the distribution of heating along the length of the filament. We find that the prominence is heated to a temperature above the quiet Sun temperature at 17 GHz. The duration of the dimming is the time taken by the eruptive prominence in passing over the flaring region. We also find evidence for the obscuration in EUV images obtained by the Solar and Heliospheric Observatory (SOHO) mission.
Linearity Properties of Bayes Nets with Binary Variables

It is "well known" that in linear models: (1) testable constraints on the marginal distribution of observed variables distinguish certain cases in which an unobserved cause jointly influences several observed variables; (2) the technique of "instrumental variables" sometimes permits an estimation of the influence of one variable on another even when the association between the variables may be confounded by unobserved common causes; (3) the association (or conditional probability distribution of one variable given another) of two variables connected by a path or pair of paths with a single common vertex (a trek) can be computed directly from the parameter values associated with each edge in the trek; (4) the association of two variables produced by multiple treks can be computed from the parameters associated with each trek; and (5) the independence of two variables conditional on a third implies the corresponding independence of the sums of the variables over all units conditional on the sums over all units of each of the original conditioning variables. These properties are exploited in search procedures. We show that (1) and (2) hold for all Bayes nets with binary variables. We further show that for Bayes nets parameterized as noisy-OR and noisy-AND gates, all of these properties save (4) hold.
Cutset sampling for Bayesian networks

The paper presents a new sampling methodology for Bayesian networks that samples only a subset of variables and applies exact inference to the rest. Cutset sampling is a network structure-exploiting application of the Rao-Blackwellisation principle to sampling in Bayesian networks. It improves convergence by exploiting memory-based inference algorithms. It can also be viewed as an anytime approximation of the exact cutset-conditioning algorithm developed by Pearl. Cutset sampling can be implemented efficiently when the sampled variables constitute a loop-cutset of the Bayesian network and, more generally, when the induced width of the network's graph conditioned on the observed sampled variables is bounded by a constant w. We demonstrate empirically the benefit of this scheme on a range of benchmarks.
Controllable steep dispersion with gain in a four-level N-scheme with four-wave mixing

We present a theoretical analysis of the propagation of light pulses through a medium of four-level atoms, with two strong pump fields and a weak probe field in an N-scheme arrangement. We show that four-wave mixing has a profound effect on the probe-field group velocity and absorption, allowing the probe-field propagation to be tuned from superluminal to slow-light regimes with amplification.
Capacity of the MIMO interference channel to within a constant gap

The capacity region of the 2-user multi-input multi-output (MIMO) Gaussian interference channel (IC) is characterized to within a constant gap that is independent of the signal-to-noise ratio (SNR) and all channel parameters. The general MIMO IC is considered with an arbitrary number of antennas at each node. For a class of MIMO ICs characterized by the relation between the numbers of antennas at the different nodes this gap is strictly smaller than the gap in a previous result obtained by Telatar and Tse. For instance, the gap for the SIMO IC with single antenna transmitters and N-antenna receivers obtained here is 1 bit, instead of N bits. Moreover, a simple (or universal) and an explicit achievable coding scheme are given here that have the constant-gap-to-capacity property. Consequently, explicit upper and lower bounds to the capacity region are obtained. A reciprocity result is also proved which is that the capacity of the reciprocal MIMO IC is within a constant gap of the capacity region of the forward MIMO IC.
Varying degrees of nonlinear mechanical behavior arising from geometric differences of urogynecological meshes.

Synthetic polypropylene meshes were designed to restore pelvic organ support for women suffering from pelvic organ prolapse; however, the FDA released two notifications regarding the potential complications associated with mesh implantation. Our aim was to characterize the structural properties of Restorelle and UltraPro subjected to uniaxial tension along perpendicular directions, and then model the tensile behavior of these meshes utilizing a co-rotational finite element model, with an imbedded linear or fiber-recruitment local stress-strain relationship. Both meshes exhibited highly nonlinear stress-strain behavior; Restorelle had no significant differences between the two perpendicular directions, while UltraPro had a 93% difference in the low (initial) stiffness (p=0.009) between loading directions. Our model predicted that early alignment of the mesh segments in the loading direction and subsequent stretching could explain the observed nonlinear tensile behavior. However, a nonlinear stress-strain response in the stretching regime, that may be inherent to the mesh segment, was required to better capture experimental results. Utilizing a nonlinear fiber recruitment model with two parameters A and B, we observed improved agreement between the simulations and the experimental results. An inverse analysis found A=120 MPa and B=1.75 for Restorelle (RMSE=0.36). This approach yielded A=30 MPa and B=3.5 for UltraPro along one direction (RMSE=0.652), while the perpendicular orientation resulted in A=130 MPa and B=4.75 (RMSE=4.36). From the uniaxial protocol, Restorelle was found to have little variance in structural properties along these two perpendicular directions; however, UltraPro was found to behave anisotropically.
Roles of c-FLIP in Apoptosis, Necroptosis, and Autophagy

Cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein (c-FLIP) is a major antiapoptotic protein and an important cytokine and chemotherapy resistance factor that suppresses cytokine- and chemotherapyinduced apoptosis. c-FLIP is expressed as long (c-FLIPL), short (c-FLIPS), and c-FLIPR splice variants in human cells. c-FLIP binds to FADD and/or caspase-8 or -10 and TRAIL receptor 5 (DR5). This interaction in turn prevents Death-Inducing Signaling Complex (DISC) formation and subsequent activation of the caspase cascade. c-FLIPL and c-FLIPS are also known to have multifunctional roles in various signaling pathways, as well as activating and/ or upregulating several cytoprotective and pro-survival signaling proteins including Akt, ERK, and NF-κB. In addition to its role in apoptosis, c-FLIP is involved in programmed necroptosis (necrosis) and autophagy. Necroptosis is regulated by the Ripoptosome, which is a signaling intracellular cell death platform complex. The Ripoptosome contains receptor-interacting protein-1/Receptor-Interacting Protein-3 (RIP1), caspase-8, caspase-10, FADD, and c-FLIP isoforms involved in switching apoptotic and necroptotic cell death. c-FLIP regulates the Ripoptosome; in addition to its role in apoptosis, it is therefore also involved in necrosis. c-FLIPL attenuates autophagy by direct acting on the autophagy machinery by competing with Atg3 binding to LC3, thereby decreasing LC3 processing and inhibiting autophagosome formation. Upregulation of c-FLIP has been found in various tumor types, and its silencing has been shown to restore apoptosis triggered by cytokines and various chemotherapeutic agents. Hence, c-FLIP is an important target for cancer therapy. This review focuses on (1) the anti-apoptotic role of c-FLIP splice variants in preventing apoptosis and inducing cytokine and chemotherapy drug resistance, as well as its roles in necrosis and autophagy, and (2) modulation of c-FLIP expression as a means to enhance apoptosis and modulate necrosis and autophagy in cancer cells.
Updown Numbers and the Initial Monomials of the Slope Variety

Let $I_n$ be the ideal of all algebraic relations on the slopes of the ${n\choose2}$ lines formed by placing $n$ points in a plane and connecting each pair of points with a line. Under each of two natural term orders, the ideal of $I_n$ is generated by monomials corresponding to permutations satisfying a certain pattern-avoidance condition. We show bijectively that these permutations are enumerated by the updown (or Euler) numbers, thereby obtaining a formula for the number of generators of the initial ideal of $I_n$ in each degree.
A General and Efficient Synthesis of Sulfonylbenzotriazoles from N-Chlorobenzotriazole and Sulfinic Acid Salts

One-pot reactions of sulfinic acid salts (produced from organometallic reagents with SO2) with N-chlorobenzotriazole gave the corresponding N-alkane-, N-arene-, and N-heteroenesulfonylbenzotriazoles 3a−j in 41−93% yields. Reagents 3a−j are efficient sulfonylating agents, reacting at 20−80 °C with various primary and secondary aliphatic amines to yield the corresponding sulfonamides in 64−100% yields.
Direct Oxidative Cleavage of α- and β-Dicarbonyls and α-Hydroxyketones to Diesters with KHSO5

Presented is a methodology to oxidatively cleave α-hydroxyketones and α- or β-diones using the environmentally benign reagent KHSO5, prepared easily from Oxone, to diesters in one simple transformation. In addition, we undertook a mechanistic study to provide a plausible mechanistic interpretation. These reactions may prove to be valuable alternatives to other related metal-mediated processes.
Effective pseudo-potentials of hydrodynamic origin

It is shown that low Reynolds number fluid flows can cause suspended particles to respond as though they were in an equilibrium system with an effective potential. This general result follows naturally from the fact that different methods of moving particles in viscous fluids give rise to very different long-range flows. Two examples are discussed: electrophoretic ‘levitation’ of a heavy charged sphere, for which a hydrodynamic ‘pseudo-potential’ can be written in closed form, and quasi-two-dimensional crystals of like-charged colloidal spheres which form near charged walls, whose apparent attraction arises not from a force but from persistent fluid flows.
Nonparametric and Semi-Nonparametric Recreational Demand Analysis

This paper addresses issues of specification testing for the travel cost method (TCM). Two nonparametric approaches to TCM analysis are presented. In addition, semi- nonparametric count models for TCM are developed.A numerical illustration isprovided in which the three methodsare applied to an actual TCM data set on waterfowl hunting and the results are compared to those from a parametric analysis.
Precipitation particle impact noise in aircraft antennas

It has been found that precipitation static noise is produced in antennas under plastic surfaces, even though these surfaces are covered by conductive films. In this paper, the noise is shown to be due to a noise-producing mechanism associated with the acquisition of charge by individual precipitation particles upon impact in the antenna field region. The existence of such a mechanism is demonstrated theoretically and substantiated by experiment. Production of such noise in antennas is analogous to production of shot noise in vacuum tubes. Calculated results indicate that in practical antennas this process is capable of generating noise voltages sufficient to disable lf and mf equipment such as the adf radio compass.