cssi/SciSciGPT-SciSciNet huggingface dataset:
Black Holes and Relativistic Jets

There is strong observational evidence that AGN, Galactic X-ray transients and (probably) $\gamma$-ray bursts are associated with black holes, and that these sources are able to form collimated, ultrarelativistic outflows. There is much interest in trying to understand how these prime movers are able to release energy from accreting gas and their own spin energy. Electromagnetic field plays a large role in many of the mechanisms under active consideration. In this article, several of the many possible ``metabolic pathways'' through which mass, angular momentum and energy can flow around and away from black hole magnetospheres are discussed. Particular importance is attached to the interactions between the inflowing disk, the outflowing wind, the black hole and the jet. Some important unresolved questions are identified and it is argued that large scale numerical computation will almost certainly be necessary to address them.
WIN55212-2 docking to the CB1 cannabinoid receptor and multiple pathways for conformational induction.

Key pharmacophoric elements for the (aminoalkyl)indole (AAI) CB1 cannabinoid receptor agonists are the aminoalkyl moiety, the lipophilic aroyl group, and the heterocyclic indole ring. In the present study, the docking space allowed for (R)-[2,3-dihydro-5-methyl-3-[(4-morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl](1-naphthalenyl)methanone (WIN55212-2; 1) within the CB1 receptor was extensively explored by a docking approach that combines Monte Carlo (MC) and molecular dynamics (MD) simulations. The goals were to understand the key binding interactions of AAIs within the CB1 receptor and to examine the role of the ligand in inducing a receptor conformational change. From the findings of extensive SAR studies on the cannabinoid compounds and correlation between AAI binding affinity data and calculated binding energies, we proposed two alternative binding conformations, aroyl-up1 and aroyl-up2. These denote the directionality of the ligand naphthyl ring within the receptor upward with respect to th...
In Vivo Systems Analysis Identifies Spatial and Temporal Aspects of the Modulation of TNF-α–Induced Apoptosis and Proliferation by MAPKs

Cellular responses to external stimuli depend on dynamic features of multipathway network signaling; thus, cell behavior is influenced in a complex manner by the environment and by intrinsic properties. Methods of multivariate systems analysis have provided an understanding of these convoluted effects, but only for relatively simplified examples in vitro. To determine whether such approaches could be successfully used in vivo, we analyzed the signaling network that determines the response of intestinal epithelial cells to tumor necrosis factor–α (TNF-α). We built data-driven, partial least-squares discriminant analysis (PLSDA) models based on signaling, apoptotic, and proliferative responses in the mouse small intestinal epithelium after systemic exposure to TNF-α. The extracellular signal–regulated kinase (ERK) signaling axis was a critical modulator of the temporal variation in apoptosis at different doses of TNF-α and of the spatial variation in proliferation in distinct intestinal regions. Inhibition of MEK, a mitogen-activated protein kinase kinase upstream of ERK, altered the signaling network and changed the temporal and spatial phenotypes consistent with model predictions. Our results demonstrate the dynamic, adaptive nature of in vivo signaling networks and identify natural, tissue-level variation in responses that can be deconvoluted only with quantitative, multivariate computational modeling. This study lays a foundation for the use of systems-based approaches to understand how dysregulation of the cellular network state underlies complex diseases.
Statistical and visual morph movie analysis of crystallographic mutant selection bias in protein mutation resource data.

Structural studies of the effects of non-silent mutations on protein conformational change are an important key in deciphering the language that relates protein amino acid primary structure to tertiary structure. Elsewhere, we presented the Protein Mutant Resource (PMR) database, a set of online tools that systematically identified groups of related mutant structures in the Protein DataBank (PDB), accurately inferred mutant classifications in the Gene Ontology using an innovative, statistically rigorous data-mining algorithm with more general applicability, and illustrated the relationship of these mutant structures via an intuitive user interface. Here, we perform a comprehensive statistical analysis of the effect of PMR mutations on protein tertiary structure. We find that, although the PMR does contain spectacular examples of conformational change, in general there is a counter-intuitive inverse relationship between conformational change (measured as C-alpha displacement or RMS of the core structure) and the number of mutations in a structure. That is, point mutations by structural biologists present in the PDB contrast naturally evolved mutations. We compare the frequency of mutations in the PMR/PDB datasets against the accepted PAM250 natural amino acid mutation frequency to confirm these observations. We generated morph movies from PMR structure pairs using technology previously developed for the Macromolecular Motions Database (), allowing bioinformaticians, geneticists, protein engineers, and rational drug designers to analyze visually the mechanisms of protein conformational change and distinguish between conformational change due to motions (e.g., ligand binding) and mutations. The PMR morph movies and statistics can be freely viewed from the PMR website, .
Global Behavior of a Nonlinear Quasiperiodic Mathieu Equation

In this paper, we investigate the interaction of subharmonicresonances in the nonlinear quasiperiodic Mathieu equation,x + [δ + e (cos ω1 t + cos ω2 t)] x + αx3 = 0.We assume that e ≪ 1 and that the coefficient of the nonlinearterm, α, is positive but not necessarily small.We utilize Lie transform perturbation theory with elliptic functions –rather than the usual trigonometric functions – to study subharmonic resonances associated with orbits in 2m:1 resonance with a respective driver. In particular, we derive analytic expressions that place conditions on (δ, e, ω1, ω2) at which subharmonic resonance bands in a Poincare section of action space begin to overlap. These results are used in combination with Chirikov's overlap criterion to obtain an overview of the O(e) global behavior of equation (1) as a function of δ and ω2 with ω1, α, and e fixed.
Ab initio calculations of elastic constants of plagioclase feldspars

Plagioclase feldspars comprise a large portion of the Earth’s crust and are very anisotropic, making accurate knowledge of their elastic properties important for understanding the crust’s anisotropic seismic signature. However, except for albite, existing elastic constants for plagioclase feldspars are derived from measurements that cannot resolve the triclinic symmetry. We calculate elastic constants for plagioclase end-members albite NaAlSi3O8 and anorthite CaAl2Si2O8 and intermediate andesine/labradorite NaCaAl3Si5O16 using density functional theory to compare with and improve existing elastic constants and to study trends in elasticity with changing composition. We obtain elastic constants similar to measured elastic constants and find that anisotropy decreases with anorthite content.
Town versus Gown: The Effect of a College on Housing Prices and the Tax Base

This paper investigates whether the presence of college increases house prices and the tax base. Colleges provide cultural and recreational amenities to the surrounding area but lifestyle choices of students may create negative externalities that depress property prices. In addition, colleges are exempt from property taxes. While the property tax exemption reduces the tax base, the amenity value of the college may cause more development on the remaining land. Previous literature considers the impact of a wide range of amenities including open space, however, none try to capture the effect from a college in a given area. We find that the presence of a college is associated with house prices that are about 11 percent higher. However, the interaction of the college dummy and enrollment is also significant and negative. Taken together, the results suggest that small colleges have the largest effect on house prices and the positive effect on house prices disappears once the college enrollment reaches about 12,500 students. We also find that the effect on house prices is stronger for four-year colleges (14 percent higher) and that the source of the differential is the degree to which the college is residential. For the tax base, the story is simpler. The presence of a college is associated with a tax base that is about 24 percent higher. As is the case with house prices, the effect of a four-year college on the tax base is stronger (about 32 percent) than the effect of a community college. However, neither the size of the college nor the degree to which the college is residential has an impact on the tax base.
Learning Schooling Behavior from Observation

Agent-based simulation is a valuable tool for biologists studying animal behavior, however constructing models for simulation is often a time-consuming manual task, and validation of these models requires a principled approach. We present a framework for using machine learning techniques to automatically construct behaviors from tracking data of live animals from video that can be run in a simulated environment. Using this framework, we provide results for automatically learning the schooling behavior of Notemigonus crysoleucas.
A corporate governance agenda for developing countries

ESTE ARTICULO PRESENTA LOS RESULTADOS DE UNA INVESTIGACION DOCTORAL REALIZADA DENTRO DEL PROGRAMA DE POSGRADO EN CIENCIAS DE LA ADMINISTRACION EN LA UNIVERSIDAD NACIONAL AUTONOMA DE MEXICO. LA APORTACION PRINCIPAL ES UNA PROPUESTA PARA CREAR UN NUEVO ESTADO FINANCIERO DENOMINADO ESTADO DE GENERACION DE VALOR. ESTA PROPUESTA PUEDE BRINDAR A LOS INVERSIONISTAS Y A TODOS LOS USUARIOS DE LA INFORMACION ELEMENTOS QUE LOS ESTADOS FINANCIEROS TRADICIONALES NO CONTIENEN COMO LA CAPACIDAD QUE LA EMPRESA HA TENIDO Y TENDRA PARA GENERAR VALOR. AL INCLUIR EL VALOR QUE DE LA EMPRESA SE ESPERA TENER EN EL FUTURO, SE CAMBIA LA TENDENCIA TRADICIONAL EN RELACION CON LOS NUMEROS QUE ENCONTRAMOS EN LOS ESTADOS FINANCIEROS, PUES SOLO REPRESENTAN LOS ACONTECIMIENTOS PASADOS. CABE SENALAR QUE EL METODO DE VALUACION DE EMPRESAS QUE MAYOR CONSISTENCIA TIENE EN SU APLICACION CON LAS METRICAS DE CREACION DE VALOR ECONOMICO ES EL METODO GOODWILL. POR OTRA PARTE, EL MODELO BLACK Y SCHOLES NO NOS VA A BRINDAR EL VALOR EXACTO QUE LA EMPRESA TENDRA EN EL FUTURO, SINO QUE ”DADAS LAS CARACTERISTICAS DEL MISMO QUE CON BASES PROBABILISTICAS SOLIDAS INDICA EL VALOR QUE EN EL FUTURO PODRIA TENER LA EMPRESA” NOS SENALARIA SI LA EMPRESA FUE CAPAZ DE GENERAR VALOR O NO EN RELACION CON EL VALOR QUE DE ELLA MISMA SE ESPERABA.
Gene Pathways That Delay Caenorhabditis elegans Reproductive Senescence

Reproductive senescence is a hallmark of aging. The molecular mechanisms regulating reproductive senescence and its association with the aging of somatic cells remain poorly understood. From a full genome RNA interference (RNAi) screen, we identified 32 Caenorhabditis elegans gene inactivations that delay reproductive senescence and extend reproductive lifespan. We found that many of these gene inactivations interact with insulin/IGF-1 and/or TGF-β endocrine signaling pathways to regulate reproductive senescence, except nhx-2 and sgk-1 that modulate sodium reabsorption. Of these 32 gene inactivations, we also found that 19 increase reproductive lifespan through their effects on oocyte activities, 8 of them coordinate oocyte and sperm functions to extend reproductive lifespan, and 5 of them can induce sperm humoral response to promote reproductive longevity. Furthermore, we examined the effects of these reproductive aging regulators on somatic aging. We found that 5 of these gene inactivations prolong organismal lifespan, and 20 of them increase healthy life expectancy of an organism without altering total life span. These studies provide a systemic view on the genetic regulation of reproductive senescence and its intersection with organism longevity. The majority of these newly identified genes are conserved, and may provide new insights into age-associated reproductive senescence during human aging.
The Lagrangian filtration of the mapping class group and finite-type invariants of homology spheres

In a recent paper we defined a new filtration of the mapping class group – the Lagrangian filtration. We here determine the successive quotients of this filtration, up to finite index. As an application we show that, for any additive invariant of finite-type (e.g. the Casson invariant) and any level of the Lagrangian filtration, there is a homology 3-sphere which has a Heegaard decomposition whose gluing diffeomorphism lies at that level, on which this invariant is non-zero. In a final section we examine the relationship between the Johnson and Lagrangian filtrations.
Restrictions of Steiner Bundles and Divisors on the Hilbert Scheme of Points in the Plane

The Hilbert scheme of n points in the projective plane parameterizes degree n zero-dimensional subschemes of the projective plane. We examine the dual cones of effective divisors and moving curves on the Hilbert scheme. By studying interpolation, restriction, and stability properties of certain vector bundles on the plane we fully determine these cones for just over three fourths of all values of n. A general Steiner bundle on P is a vector bundle E admitting a resolution of the form 0 → OPN (−1) s M → O PN → E → 0, where the map M is general. We complete the classification of slopes of semistable Steiner bundles on P by showing every admissible slope is realized by a bundle which restricts to a balanced bundle on a rational curve. The proof involves a basic question about multiplication of polynomials on P which is interesting in its own right.
FACTORS INFLUENCING THE PROPENSITY FOR CROSS-BORDER TRADE

We estimate a simultaneous bivariate qualitative choice model of Arizona agribusiness firms propensity to trade and visit as a tourist with the cross-border state of Sonora, Mexico. The trade equation is estimated as an ordered probit model with responses of: 1) a firm has not ever traded or investigated doing any trading activities with Sonora, 2) the firm has not done any trade with Sonora but they have investigated doing business in this cross-border state, and 3) the firm has traded with Sonora, either directly or through a second handler like a broker. A proprietors propensity to visit Sonora as a tourist is modeled from the binary response of whether the individual has ever visited Sonora as a tourist or not. Simultaneity arises since both trade and tourist visits are hypothesized to influence one another. Results indicate that tourist visits have a greater influence on whether firms trade than traditional variables considered like firm age and size. Venture business visits, quantified through the tourism equation, were also found to have a greater impact on an agribusiness firm's propensity to trade than traditional variables. Our results suggest that communities seeking to develop and expand cross-border trading activities should target entrepreneurs with an exploratory and venture spirit first. Then, target firms that are fairly established (over 15 years in age) and desire to diversity their production risk through multiple geographic production regions. Firm size and foreign language fluency of the agribusiness owner were found to be less significant than tourist visits, venture business visits, and firm age.
Mass transport of aluminum by momentum exchange with conducting electrons

A failure mode commonly found in high power devices and integrated circuits appears when aluminum conductors carry current densities in excess of 10/sup 5/ amperes per square centimeter at temperatures above 100/spl deg/C. The mode of failure is an open circuit which often is observed as a "crack" in the aluminum and is commonly referred to as "cracked stripe" or "disappearing aluminum." This paper presents a study of this failure mode which has been identified with the mass transport of aluminum by momentum exchange between activated aluminum ions and conducting electrons. The activation energy for the reaction has been obtained and equations relating temperature, current density and film structure to conductor life are presented. The activation energy appears to be identical to that for the lattice self-diffusion of aluminum modified by factors involving both surface diffusion and grain-boundary diffusion. These latter two factors are important in films formed by the condensation of aluminum vapor.
Physical Processes in Hollow Cathodes

Hollow cathodes with cavity diameters of 1.9 cm have been operated in an MPD arc configuration at discharge currents from 0.25 kA to 30 kA. Current and potential distributions, measured with probes in the cathode cavity, show that a spontaneous mode of hollow cathode operation, wherein the current distribution penetrates upstream into the cavity, has been achieved for particular combinations of discharge current and mass flows. These measured distributions are consistent with a conduction model which suggests that maximum current penetration, and the more efficient cathode emission which accompanies it, occurs when the dominant mean free path for electron energy exchange is comparable to the cavity diameter.
Endoscopic Treatment of Acute Biliary Diseases: Have We Optimized the Value of Inpatient Endoscopic Retrograde Cholangiopancreatography?

Endoscopic retrograde cholangiopancreatography (ERCP) developed as a novel imaging modality for the pancreatobiliary tree in an era when cross-sectional imaging was extraordinarily limited. Now principally a therapeutic procedure, ERCP with biliary sphincterotomy, stone extraction, and stent placement has transformed the management of acute cholangitis, choledocholithiasis, and selected patients with acute gallstone pancreatitis. These indications have lower risk and complexity compared with other reasons for ERCP, yet at least 5%–10% of cases still result in technical failure or complications despite recent advances in the prevention of post-ERCP pancreatitis. Among high-risk patients, these include the use of prophylactic pancreatic duct stents, rectal indomethacin, and perhaps greater intravenous volume infusion.1–4 Analyzing 166,438 admissions derived from the Nationwide Inpatient Sample (NIS), James et al5 report significant reductions from 1998 to 2008 in same-stay mortality and ERCP failure rates among patients admitted for acute cholangitis, choledocholithiasis, or acute pancreatitis, henceforth referred to as acute biliary diseases. Have we optimized the delivery of inpatient ERCP services?
Approximation using scattered shifts of a multivariate function

The approximation of a general d-variate function f by the shifts �(� − �), � ∈ � ⊂ R d , of a fixed functionoccurs in many applications such as data fit- ting, neural networks, and learning theory. When � = hZ d is a dilate of the integer lattice, there is a rather complete understanding of the approximation problem (6, 18) using Fourier techniques. However, in most applications the center set � is either given, or can be chosen with complete freedom. In both of these cases, the shift-invariant setting is too restrictive. This paper studies the approximation problem in the caseis arbitrary. It establishes approximation theorems whose error bounds reflect the local density of the points in �. Two different settings are analyzed. The first is when the setis prescribed in advance. In this case, the theorems of this paper show that, in analogy with the classical univariate spline ap- proximation, improved approximation occurs in regions where the density is high. The second setting corresponds to the problem of non-linear approximation. In that setting the setcan be chosen using information about the target function f. We discuss how to 'best' make these choices and give estimates for the approximation error.
Interim qualification tests and procedures for terrestrial photovoltaic thin-film flat-plate modules

Recommended procedures and specifications are presented for qualification tests to evaluate terrestrial thin-film flat-plate photovoltaic (PV) nonconcentrating modules designed for power generation. The qualification tests are designed to evaluate PV module design performance and susceptibility to known failure mechanisms. Emphasis is placed on testing and evaluating module performance characteristics and design features that will affect the degradation of module performance and physical properties resulting from solar exposure, environmental weathering, mechanical loading, corrosion, and module shadowing. The primary intent is to provide the minimum tests and inspections required to evaluate PV modules and to provide a common approach (e.g., between producer and purchaser) in conducting qualification tests. >
Bulk Gauge Fields in the Randall-Sundrum Model

Abstract We explore the consequences of placing the Standard Model gauge fields in the bulk of the recently proposed localized gravity model of Randall and Sundrum. We find that the Kaluza–Klein excitations of these fields are necessarily strongly coupled and we demonstrate that current precision electroweak data constrain the lowest states to lie above ≃23 TeV. Taking the weak scale to be ∼1 TeV, the resulting implications on the model parameters force the bulk curvature, R5, to be larger than the higher dimensional Planck scale, M, violating the consistency of the theory. In turn, to preserve |R5|≲M2, the weak scale must be pushed to ≳100 TeV. Hence we conclude that it is disfavored to place the Standard Model gauge fields in the bulk of this model as it is presently formulated.
Dynamics of vibrated granular monolayers

We study statistical properties of vibrated granular monolayers using molecular dynamics simulations. We show that at high excitation strengths, the system is in a gas state, particle motion is isotropic, and the velocity distributions are Gaussian. As the vibration strength is lowered, the system's dimensionality is effectively reduced from three to two. Below a critical excitation strength, a cluster phase occurs, and the velocity distribution becomes bimodal. In this phase, the system consists of clusters of immobile particles arranged in close-packed hexagonal arrays, and gas particles whose energy equals the first excited state of an isolated particle on a vibrated plate.
Understanding Compact Object Formation and Natal Kicks. I. Calculation Methods and the Case of GRO J1655–40

In recent years proper-motion measurements have been added to the set of observational constraints on the current properties of Galactic X-ray binaries. We develop an analysis that allows us to consider all this available information and reconstruct the full evolutionary history of X-ray binaries back to the time of core collapse and compact object formation. This analysis accounts for five evolutionary phases: mass transfer through the ongoing X-ray phase, tidal circularization before the onset of Roche lobe overflow, motion through the Galactic potential after the formation of the compact object, binary orbital dynamics at the time of core collapse, and hydrodynamic modelingofthecorecollapsethatconnectsthecompactobjecttoitsprogenitorandanynucleosyntheticconstraints available. In this first paper we present this analysis in a comprehensive manner and apply it to the soft X-ray transient GRO J1655� 40. This is the first analysis that incorporates all observational constraints on the current system properties and uses the full three-dimensional peculiar velocity constraints right after core collapse instead of lower limits on the current space velocity given by the present-day radial velocity. We find that the system has remained within 200 pc from the Galactic plane throughout its entire lifetime and that the mass loss and a kick possiblyassociatedwiththeblackholeformationimpartedakickvelocityof ’45‐115kms � 1 tothebinary’scenter
Thermal/fluid characteristics of 3-D woven mesh structures as heat exchanger surfaces

The present work demonstrates the fabrication methodology of a three-dimensional (3-D), aluminum wire filament, bonded mesh deployed as a heat exchange surface. A model of the effective thermal conductivity of the mesh is developed. Apparatus to measure the coolant pressure-drop and heat transfer coefficient are described. Measurements are reported for fabricated test samples of varying thickness. Mesh Stanton number and friction factor correlations for a coolant with Prandtl number equal to 9.5 (chilled water) are reported. A heat exchanger performance evaluation, comparing the 3-D woven mesh technology to another exchanger surface technology, is described. We have found that the weaving/wire bonding process must be carefully controlled to insure that target porosity, specific surface area and effective thermal conductivity are achieved. Effective thermal conductivities are found to be at least two-times larger than achieved in other comparable porous media configurations. Mesh friction factor and Stanton number are comparable to those achieved with other exchanger surface technologies. The exchanger performance comparison shows that exchangers having superior performance can be configured.
Turbulence Measurements in a Compressible Reattaching Shear Layer

Detailed hot-wire measurements of the longitudinal component of the mass-flow fluctuations have been made in an approximately self-preserving free shear layer reattaching on a 20-deg ramp at Mach number 2.9. The experimental configuration is especially designed to provide a well-defined initial condition for the reattachment process. The absolute mass-flow turbulence intensity increases dramatically through the compression in the reattachment region, which is in sharp contrast to similar subsonic reattachments. It is clear that the mean dilatation contributes significantly to the turbulence amplification. In addition, the length scale is affected strongly by the presence of extra strain rates. Prediction of this flow will require some sophisticated modeling, and the challenge to the predictor is clear.
A discussion of E-pulse method and Prony's method for radar target resonance retrieval from scattered field

An efficient version of the E-pulse method is discussed and generalized in the context of radar target pole retrieval from the scattered field. Its relation to the generalized Prony's method is investigated. It is shown that the E-pulse method can be efficiently implemented using a smoothing-and-sampling procedure and a Prony's approach. The tradeoff between noise insensitivity and computational burden influenced by various parameters is pointed out. >
Free field realizations in representation theory and conformal field theory

Free field realization is a relatively new formalism that intertwines representation theory, conformal field theory, and the theory of nonlinear integrable equations. From the physics point of view, it provides realizations of two-dimensional conformal field theories via free bosonic theories. This allows one to find integrals of motion and compute explicitly correlation functions. Mathematically, free field realizations bring new insights into representation theory of conformal algebras, e.g., a new series of representations of affine Kac-Moody algebras, which can be considered as an analogue of the principal series of semi-simple groups over local fields. This connects representation theory of affine algebras with Langlands philosophy.
An optimal controller arising from minimization of a quadratic performance criterion of indefinite form

The problem of minimizing energy loss in automatic steering of ships is considered. Two ship types are analyzed-a high-speed containership and a large oil tanker. Making use of the sufficiency conditions for existence of a stable closed-loop system, it is shown that there is no theoretical difficulty in using an exact performance criterion for energy losses due to steering with an indefinite form, rather than an approximate criterion which fits the positive semidefiniteness condition of standard linear regulator (LR) theory.
Robot Assisted Gait Training With Active Leg Exoskeleton (ALEX)

Gait training of stroke survivors is crucial to facilitate neuromuscular plasticity needed for improvements in functional walking ability. Robot assisted gait training (RAGT) was developed for stroke survivors using active leg exoskeleton (ALEX) and a force-field controller, which uses assist-as-needed paradigm for rehabilitation. In this paradigm undesirable gait motion is resisted and assistance is provided towards desired motion. The force-field controller achieves this paradigm by effectively applying forces at the ankle of the subject through actuators on the hip and knee joints. Two stroke survivors participated in a 15-session gait training study each with ALEX. The results show that by the end of the training the gait pattern of the patients improved and became closer to a healthy subject's gait pattern. Improvement is seen as an increase in the size of the patients' gait pattern, increased knee and ankle joint excursions and increase in their walking speeds on the treadmill.
Photoisomerization by Hula-twist. Photoactive biopigments

A review of literature on photoisomerization of bilirubin and photoactive yellow protein suggests possible involvement of the volume-conserving Hula-twist (HT) reaction mechanism in their primary photochemical processes. Additional definitive experiments to verify their involvement are proposed. Information related to photoproducts of bacteri- orhodopsin, rhodopsin, and phytochrome are reviewed. For carotenoids, because of partici- pation of the longer lived triplet state in, for example, the photosynthetic apparatus, the involvement of HT is probably less likely.
Technology Assimilation Across the Value Chain: An Empirical Study of Small and Medium-Sized Enterprises

In this paper, the authors study technology assimilation, aggregating technologies and assimilation stages for SMEs. The authors employ the twin lenses of organizational innovation and elements of institutional theory. The research validates some institutional actors and most firm characteristics as important determinants. The relative weaknesses of the institutional actors provide evidence of structural isolation in the SME environment that is inhibiting information flow from intermediaries like government support agencies and vendors. The authors recommend a proactive role on the part of technology and enterprise intermediaries to design SME-appropriate solutions.
ECDIS Sea Trials

In 1989 the International Maritime Organization (IMO) published its Provisional Performance Standards (PPS) for ECDIS (Electronic Chart Display and Information Systems) and asked member governments to assess these standards and submit their findings to the Sub-Committee on Safety of Navigation. IMO intends to finalize the standards in 1993.
La sombra de Bonifacio Reyes en "Su único hijo"

Aquella era la fuente … iLa cadena de los padres y los hijos! Cadena que remontandose por sus eslabones hacia el pasado, seria toda amor, abnegacion, la unidad sincera, real, caritativa de la pobre raza humana; pero la cadena venia de lo pasado a lo presente, a lo futuro, y era cadena que la muerte rompia en cada eslabon; era el olvido, la indiferencia. Le parecia estar solo en el mundo, sin lazo de amor que fuese un amparo, y comprendia, sin embargo, que el era el producto de la abnegacion ajena, del sacrificio amoroso en indefinida serie. iOh infinito consuelo! El origen debia de ser tambien acto de amor … Bonifacio se habia vuelto un poco hacia la pared; la luz, colocada en la mesilla de noche, pintaba el perfil de su rostro en la sombra sobre el estuco blanco. Su sombra, ya lo habia notado otras veces con melancolico consuelo, se parecia a la de su padre, tal como la veia en los recuerdos lejanos … ‘iCosa extrana! Yo no me parecia apenas nada a mi padre, y nuestras sombras si, muchisimo’.
Impact of Size Effect on Graphene Nanoribbon Transport

Graphene has shown impressive properties for nanoelectronics applications, including a high mobility and a widthdependent bandgap. Use of graphene in nanoelectronics would most likely be in the form of graphene nanoribbons (GNRs) where the ribbon width is expected to be less than 20 nm. Many theoretical projections have been made on the impact of edge scattering on carrier transport in GNRs-most studies point to a degradation of mobility (of GNRs) as well as the on/off ratio (of GNR FETs). This letter provides the first clear experimental evidence of the onset of size effect in patterned GNRs; it is shown that, for W < 60 nm, carrier mobility in GNRs is limited by edge scattering.
On isolating points using disks

In this paper, we consider the problem of choosing disks (that we can think of as corresponding to wireless sensors) so that given a set of input points in the plane, there exists no path between any pair of these points that is not intercepted by some disk. We try to achieve this separation using a minimum number of a given set of unit disks. We show that a constant factor approximation to this problem can be found in polynomial time using a greedy algorithm. To the best of our knowledge we are the first to study this optimization problem.
Probing the large-scale structure around the most distant galaxy clusters from the massive cluster survey

We present maps of the cosmic large-scale structure around the 12 most distant galaxy clusters from the Massive Cluster Survey (MACS) as traced by the projected surface density of galaxies on the cluster red sequence. Taken with the SuprimeCam wide-field camera on the Subaru telescope, the images used in this study cover a 27 x 27 arcmin 2 area around each cluster, corresponding to 10 x 10 Mpc 2 at the median redshift of z = 0.55 of our sample. We directly detect satellite clusters and filaments extending over the full size of our imaging data in the majority of the clusters studied, supporting the picture of mass accretion via infall along filaments suggested by numerical simulations of the growth of clusters and the evolution of large-scale structure. A comparison of the galaxy distribution near the cluster cores with the X-ray surface brightness as observed with Chandra reveals, in several cases, significant offsets between the gas and galaxy distribution, indicative of ongoing merger events. The respective systems are ideally suited for studies of the dynamical properties of gas, galaxies and dark matter. In addition, the large-scale filaments viewed at high contrast in these MACS clusters are prime targets for the direct detection and study of the warm-hot intergalactic medium (WHIM).
Dynamic clustering for acoustic target tracking in wireless sensor networks

We devise and evaluate a fully decentralized, light-weight, dynamic clustering algorithm for target tracking. Instead of assuming the same role for all the sensors, we envision a hierarchical sensor network that is composed of 1) a static backbone of sparsely placed high-capability sensors which assume the role of a cluster head (CH) upon triggered by certain signal events and 2) moderately to densely populated low-end sensors whose function is to provide sensor information to CHs upon request. A cluster is formed and a CH becomes active, when the acoustic signal strength detected by the CH exceeds a predetermined threshold. The active CH then broadcasts an information solicitation packet, asking sensors in its vicinity to join the cluster and provide their sensing information. We address and devise solution approaches (with the use of Voronoi diagram) to realize dynamic clustering: (I1) how CHs operate with one another to ensure that only one CH (preferably the CH that is closes to the target) is active with high probability, (I2) when the active CH solicits for sensor information, instead of having all the sensors in its vicinity reply, only a sufficient number of sensors respond with nonredundant, essential information to determine the target location, and (I3) both the packets that sensors send to their CHs and packets that CHs report to subscribers do not incur significant collision. Through both probabilistic analysis and ns-2 simulation, we use with the use of Voronoi diagram, the CH that is usually closes to the target is (implicitly) selected as the leader and that the proposed dynamic clustering algorithm effectively eliminates contention among sensors and renders more accurate estimates of target locations as a result of better quality data collected and less collision incurred.
Some advances in transformation-based part of speech tagging

Most recent research in trainable part of speech taggers has explored stochastic tagging. While these taggers obtain high accuracy, linguistic information is captured indirectly, typically in tens of thousands of lexical and contextual probabilities. In (Brill 1992), a trainable rule-based tagger was described that obtained performance comparable to that of stochastic taggers, but captured relevant linguistic information in a small number of simple non-stochastic rules. In this paper, we describe a number of extensions to this rule-based tagger. First, we describe a method for expressing lexical relations in tagging that stochastic taggers are currently unable to express. Next, we show a rule-based approach to tagging unknown words. Finally, we show how the tagger-can be extended into a k-best tagger, where multiple tags can be assigned to words in some cases of uncertainty.
Black holes in astrophysics

This paper reviews the current status of black hole (BH) astrophysics, focusing on topics of interest to a physics audience. Astronomers have discovered dozens of compact objects with masses greater than 3M⊙, the likely maximum mass of a neutron star. These objects are identified as BH candidates. Some of the candidates have masses ~5M⊙–20M⊙ and are found in x-ray binaries, while the rest have masses ~106M⊙–109.5M⊙ and are found in galactic nuclei. A variety of methods are being tried to estimate the spin parameters of the candidate BHs. There is strong circumstantial evidence that many of the objects have event horizons, so there is good reason to believe that the candidates are true BHs. Recent MHD simulations of magnetized plasma accreting on rotating BHs seem to hint that relativistic jets may be produced by a magnetic analogue of the Penrose process.
The complexity of matrix rank and feasible systems of linear equations

We characterize the complexity of some natural and important problems in linear algebra. In particular, we identify natural complexity classes for which the problems of (a) determining if a system of linear equations is feasible and (b) computing the rank of an integer matrix (as well as other problems) are complete under logspace reductions.¶As an important part of presenting this classification, we show that the "exact counting logspace hierarchy" collapses to near the bottom level. We review the definition of this hierarchy below. We further show that this class is closed under NC1-reducibility, and that it consists of exactly those languages that have logspace uniform span programs (introduced by Karchmer and Wigderson) over the rationals.¶In addition, we contrast the complexity of these problems with the complexity of determining if a system of linear equations has an integer solution.
Measured accuracy and precision in quantitative SPECT imaging with iodine-123

This study evaluated /sup 123/I SPECT volume and activity quantitation in terms of accuracy and precision using experimental phantom data. Two reconstruction methods were considered. The filtered backprojection (FB) method with 2D Metz pre-filtering and single iteration Chang attenuation compensation was compared with an iterative ML-EM method that used Gaussian post-filtering and incorporated the 3D divergent detector response and attenuation in the detection kernel. Both methods were examined over a range of resolution and noise characteristics. An ensemble of 21 SPECT data sets were acquired of a cylindrical phantom that contained spheres of size 21.4, 12.0, and 5.7 ml, filled with high purity /sup 123/I in a uniform background (5:1 uptake ratio). Each data set was reconstructed by both methods, and sphere volume and activity measurements were obtained from the reconstructions using a semi-automatic method that defines the region-of-interest based on the intensity gradient in the area of increased /sup 123/I concentration. The mean and standard deviation of the 21 measurements provided accuracy and precision indices, respectively. For the 12.0 ml sphere, the measured volume with either reconstruction method was accurate to within 5% of the true volume with a standard deviation of approximately 8% of the true volume. For the 12.0 ml sphere the measured volume with the iterative method exhibited substantially smaller standard deviation for equal accuracy compared with the FB method. Sphere activity was underestimated with both methods due to spatial resolution effects. The 5.7 ml sphere was generally below the size limit for volume and activity quantitation by these methods. >
Optimized Aeroelastic Couplings for Alleviation of Helicopter Ground Resonance

Formal optimization methods are used to determine a combination of aeroelastic coupling parameters that can alleviate ground resonance instability of a soft-inplane rotor. Optimization at a prescribed rotational speed is unable to stabilize ground resonance, as the stability objective function is satisfied merely by moving resonance to a lower rotational speed. A moving *point optimization procedure, attempting to stabilize at the rotational speed where damping is a minimum, during each optimizer iteration, is successful in stabilizing the regressing lag mode at moderate collective pitch. However, these optimal aeroelastic couplings are destabilizing near zero thrust conditions. A multi-point optimization procedure attempting to stabilize ground resonance simultaneously at low as well as high collective pitch conditions is able to restrict the instability to small values over a broad range of variation in collective pitch, and eliminate the destabilizing trend at resonance with increasing collective. This configuration could then be completely stabilized by increasing body roll damping. Negative pitch-lag coupling, positive pitch-flap coupling, flap flexibility outboard of pitch, and lag flexibility inboard of pitch, were found to be most beneficial. Decrease in roll inertia was destabilizing for the baseline as well as optimized configurations, but level of instability, if any, was lower for the optimized configuration.
Effects of Livestock Grazing on Duck Nesting Habitat in Utah

Periodic vegetation disturbance is an important yet controversial tool for waterfowl managers. Some have reported livestock grazing removes residual vegetation and thus is detrimental to nesting ducks, and others argue that such disturbance is necessary to maintain grassland health. We evaluated the impact of winter livestock grazing on duck nesting at Bear River Migratory Bird Refuge, Utah. During winter 1999, 6 experimental plots were grazed by cattle and 6 were ungrazed; in winter 2000, 8 plots were grazed and 8 were ungrazed. All grazing treatments were conducted during 15 November–15 March and averaged a stocking rate of 9.5 animal unit months/ha. During the following spring nesting season, we measured visual obstruction readings (VOR) on grazed and ungrazed sites. Although VOR on ungrazed sites were greater than those on grazed sites, this difference became less important as the nesting season progressed. Winter grazing impacted the nesting habitat of early-nesting ducks such as mallards (Anas platyrhynchos), but not that of late-nesting species such as cinnamon teal (Anas cyanoptera) and gadwall (Anas strepera). When using livestock grazing to manage grasslands, waterfowl managers should consider their management goals, the species composition of breeding duck populations, and environmental conditions.
Dynamic Pricing Algorithms for Task Allocation in Multi-agent Swarms

Over the past few years, emergent computing based techniques such as swarming have evolved as an attractive technique to design coordination protocols in large-scale distributed systems and massively multi-agent systems. In this paper, we consider a search-and-execute problem domain where agents have to discover tasks online and perform them in a distributed, collaborative manner. We specifically focus on the problem of distributed coordination between agents to dynamically allocate the tasks among themselves. To address this problem, we describe a novel technique that combines a market-based dynamic pricing algorithm to control the task priorities with a swarming-based coordination technique to disseminate task information across the agents. Experimental results within a simulated environment for a distributed aided target recognition application show that the dynamic pricing based task selection strategies compare favorably with other heuristic-based task selection strategies in terms of task completion times while achieving a significant reduction in communication overhead.
A mild and efficient one pot synthesis of 1,3,4-oxadiazoles from carboxylic acids and acyl hydrazides

Abstract A convenient one pot method for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles from acids and acyl hydrazides is reported. Acid activation with CDI, followed by coupling with the desired acylhydrazide and dehydration in the same pot with Ph 3 P and CBr 4 affords the corresponding 1,3,4-oxadiazoles in good yield. The scope of the acid and acylhydrazide components is presented.
Regioselective Suzuki coupling of benzofuran or benzothiophene boronic acids and dibromo substituted naphthalenes: synthesis of a potent inhibitor of plasminogen activator inhibitor-1

An efficient route to the biologically active naphthyl benzofuran derivative is described. The synthesis highlights a regioselective Suzuki coupling of a benzofuran and a dibromo substituted naphthalene. The scope of regioselective Suzuki coupling has been investigated.
Risks associated with drug treatments for kidney stones

Introduction: Renal stones are one of the most painful medical conditions patients experience. For many they are also a recurrent problem. Fortunately, there are a number of drug therapies available to treat symptoms as well as prevent future stone formation.Areas covered: Herein, we review the most common drugs used in the treatment of renal stones, explaining the mechanism of action and potential side effects. Search of the Medline databases and relevant textbooks was conducted to obtain the relevant information. Further details were sourced from drug prescribing manuals. Recent studies of drug effectiveness are included as appropriate.Expert opinion: Recent controversies include medical expulsive therapy trials and complex role of urinary citrate in stone disease. Future directions in research will involve new medical therapies for stone prevention, for example new drugs for hyperoxaluria.