cssi/SciSciGPT-SciSciNet huggingface dataset:
Unfolding a linker between helical repeats.

In many multi-repeat proteins, linkers between repeats have little secondary structure and place few constraints on folding or unfolding. However, the large family of spectrin-like proteins, including α-actinin, spectrin, and dystrophin, share three-helix bundle, spectrin repeats that appear in crystal structures to be linked by long helices. All of these proteins are regularly subjected to mechanical stress. Recent single molecule atomic force microscopy (AFM) experiments demonstrate not only forced unfolding but also simultaneous unfolding of tandem repeats at finite frequency, which suggests that the contiguous helix between spectrin repeats can propagate a cooperative helix-to-coil transition. Here, we address what happens atomistically to the linker under stress by steered molecular dynamics simulations of tandem spectrin repeats in explicit water. The results for α-actinin repeats reveal rate-dependent pathways, with one pathway showing that the linker between repeats unfolds, which may explain the single-repeat unfolding pathway observed in AFM experiments. A second pathway preserves the structural integrity of the linker, which explains the tandem-repeat unfolding event. Unfolding of the linker begins with a splay distortion of proximal loops away from hydrophobic contacts with the linker. This is followed by linker destabilization and unwinding with increased hydration of the backbone. The end result is an unfolded helix that mechanically decouples tandem repeats. Molecularly detailed insights obtained here aid in understanding the mechanical coupling of domain stability in spectrin family proteins.
Intelligent tutoring and assessment built on an understanding of a technical problem-solving task

In this paper we describe Hydrive, an operational computer-based intelligent tutoring system built to help Air Force technicians develop generalizable skills for troubleshooting hydraulics systems. We use Hydrive as an example of how effective training and assessment is developed from a coherent understanding of a target task and how this understanding can be consistently represented in all aspects of a training/assessment instrument. We show how an organizing principle of expert behavior, active path analysis, is used to inform the design and content of the tutor's system, student and instructional models and the design of the tutor's interface. We conclude with information about Hydrive's field trial evaluation and some thoughts on knowledge acquisition and generalizability.
Geometric Characterization of Solitons

I show that H 1 solutions of the nonlinear Schrodinger equation which are incoming converge to a soliton, in the radial case.
The Relationship between Hard X-Ray Pulse Timings and the Locations of Footpoint Sources during Solar Flares

The cause of quasi-periodic pulsations in solar flares remains the subject of debate. Recently, Nakariakov & Zimovets proposed a new model suggesting that, in two-ribbon flares, such pulsations could be explained by propagating slow waves. These waves may travel obliquely to the magnetic field, reflect in the chromosphere, and constructively interfere at a spatially separate site in the corona, leading to quasi-periodic reconnection events progressing along the flaring arcade. Such a slow wave regime would have certain observational characteristics. We search for evidence of this phenomenon during a selection of two-ribbon flares observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager, Solar and Heliospheric Observatory, and Transition Region and Coronal Explorer; the flares of 2002 November 9, 2005 January 19, and 2005 August 22. We were not able to observe a clear correlation between hard X-ray footpoint separations and pulse timings during these events. Also, the motion of hard X-ray footpoints is shown to be continuous within the observational error, whereas a discontinuous motion might be anticipated in the slow wave model. Finally, we find that for a preferential slow wave propagation angle of 25°-28° that is expected for the fastest waves, the velocities of the hard X-ray footpoints lead to estimated pulse periods and ribbon lengths significantly larger than the measured values. Hence, for the three events studied, we conclude that the observational characteristics cannot be easily explained via the Nakariakov & Zimovets propagating slow wave model when only angles of 25°-28° are considered. We provide suggested flare parameters to optimize future studies of this kind.
Intramolecular cyclopropanation of 7-diazotethered-1,3,5-cycloheptatriene: Preparation and reactions of tricyclo[5.3.0.02,10]deca-3,5-dien-9-one

Abstract The rhodium(II)-catalyzed diazo decomposition of 7-diazocarbonyltethered-1,3,5-cycloheptatriene 3 generated tricyclic ketoester 4 in 64% yield. Reaction of ketoester 4 with nucleophiles leads to cyclopropane cleavage (Nu = PhSNa) to give 5 or rearrangement (Nu = RNH 2 ) to give 7 or 8 .
Variational theory of motion of curved, twisted and extensible elastic rods

Abstract The variational theory of 3-D motions of curved twisted and extensible elastic rods is obtained based entirely on the kinematical variables of position and rotations. The constitutive relations that define the resistive couples and the axial force as gradients of the strain energy function are established. A candidate for the strain energy function, derived on the basis of classical assumptions, is presented.
Kinetic Alfvén waves and plasma transport at the magnetopause

Large amplitude compressional type ULF waves can propagate from the magnetosheath to the magnetopause where there are large gradients in density, pressure and magnetic field. These gradients efficiently couple compressional waves with shear/kinetic Alfven waves near the Alfven field-line resonance location (ω=k∥υA). We present a solution of the kinetic-MHD wave equations for this process using a realistic equilibrium profile including full ion Larmor radius effects and wave-particle resonance interactions for electrons and ions to model the dissipation. For northward IMF a KAW propagates backward to the magnetosheath. For southward IMF the wave remains in the magnetopause but can propagate through the k∥=0 location. The quasilinear theory predicts that transport due to KAWs at the magnetopause primarily results from the perpendicular electric field coupling with magnetic drift effects with diffusion coefficient D⟂ ∼ 109 m²/s. For southward IMF additional transport can occur because magnetic islands form at the k∥=0 location. Due to the broadband nature of the observed waves these islands can overlap leading to stochastic transport which is larger than that due to quasilinear effects.
Second-best instruments for near-term climate policy: Intensity targets vs. the safety valve

Abstract Current proposals for greenhouse gas emissions regulations in the United States mainly take the form of emissions caps with tradable permits. Since Weitzman's (1974) [3] study of prices vs. quantities, economic theory predicts that a price instrument is superior under uncertainty in the case of stock pollutants. Given the general belief in the political infeasibility of a carbon tax in the US, there has been recent interest in two other policy instrument designs: hybrid policies and intensity targets. We extend the Weitzman model to derive an analytical expression for the expected net benefits of a hybrid instrument under uncertainty. We compare this expression to one developed by Newell and Pizer (2006) [6] for an intensity target, and show the theoretical minimum correlation between GDP and emissions required for an intensity target to be preferred over a hybrid. In general, we show that unrealistically high correlations are required for the intensity target to be preferred to a hybrid, making a hybrid a more practical instrument in practice. We test the predictions by performing Monte Carlo simulation on a computable general equilibrium model of the US economy. The results are similar, and we show with the numerical model that when marginal abatement costs are non-linear, an even higher correlation is required for an intensity target to be preferred over a safety valve.
Chromatic number and spectral radius

Abstract Write μ ( A ) = μ 1 ( A ) ⩾ ⋯ ⩾ μ min ( A ) for the eigenvalues of a Hermitian matrix A. Our main result is: Let A be a Hermitian matrix partitioned into r × r blocks so that all diagonal blocks are zero. Then for every real diagonal matrix B of the same size as A μ ( B - A ) ⩾ μ B + 1 r - 1 A . Let G be a nonempty graph, χ ( G ) be its chromatic number, A be its adjacency matrix, and L be its Laplacian. The above inequality implies the well-known result of Hoffman χ ( G ) ⩾ 1 + μ ( A ) - μ min ( A ) , and also, χ ( G ) ⩾ 1 + μ ( A ) μ ( L ) - μ ( A ) . Equality holds in the latter inequality if and only if every two color classes of G induce a ∣ μ min ( A ) ∣ -regular subgraph.
A Convection Calibration Method for Local Heat Flux Gages

An apparatus for calibrating local heat flux gages in convective air flows is described. Heat transfer from a ''hot'' gage to a ''cold'' fluid was measured using a guarded hot-plate technique. The system was used to calibrate Gardon-type circular foil heat flux gates of 1/8 in. and 1/16 in. outer diameters. The reslts indicate that the calibration curves are nonlinear, which is different from the linear calibration obtained using the standard radiation technique. The degree of nonlinearity matches the analysis which accounts for the effect of the temperature distribution in the gage foil. The effect of this temperature distribution can be neglected in the standard radiation calibration but is often significant in convection applications. These results emphasize the importance of calibrating heat flux gates in thermal environments similar to those in which they will be used.
The Search for Anisotropy in the Arrival Directions of Ultra-High Energy Cosmic Rays Observed by the High Resolution Fly's Eye Detector in Monocular Mode

The High Resolution Fly's Eye HiRes-I detector has now been in operation in monocular mode for over six years. During that time span, HiRes-I has accumulated a larger exposure to Ultra-High Energy Cosmic Rays (UHECRs) above 10 19 eV than any other experiment built to date. This presents an unprecedented opportunity to search for anisotropy in the arrival directions of UHECRs. We present results of a search for dipole distributions oriented towards major astrophysical landmarks and a search for small-scale clustering. We conclude that the HiRes-I data set is, in fact, consistent with an isotropic source model.
A multidisciplinary optimization method for designing boundary layer ingesting inlets

The blended wing body is a revolutionary conceptual aircraft design with rear-mounted, overwing engines. Two types of engine installations are being considered for this aircraft. The more conventional design has engines installed within nacelles that are mounted on pylons above the wing surface. The engines on the second design are partially buried in the wing and use boundary-layer-ingesting inlets mounted on the wing upper surface. For both designs, and especially for the latter, the tight coupling between the aircraft aerodynamics and the propulsion system presents a challenging design integration problem. This paper presents a design method that approaches the problem using multidisciplinary optimization. A Navier―Stokes flow solver, an engine analysis method, and a nonlinear optimizer are combined to create a design tool that properly addresses the tight coupling of the problem. The appropriate objective function and constraints are identified and an effective set of design variables is selected. The optimization method is then applied to both aircraft designs as sample problems to demonstrate the capabilities of the method and to provide some preliminary insight into advantages and disadvantages of both engine installations. Potential paths for future research in this field are also discussed.
Wafer Cost Analysis for a Soft X-Ray Projection Lithography System

Abstract We present a baseline analysis of issues affecting the economic viability of Soft X-Ray Projection Lithography (SXPL). This analysis is intended to serve as a starting point, and to provide an initial assessment of the relative importance of cost factors in a SXPL system. We presume a “conventional” SXPL system design and focus on wafer exposure costs. A baseline model for system component costs and performance specifications is presented, and the dependence of wafer exposure cost on elements of the model is analyzed. Within the guidelines of our model, we find that direct cost items (e.g., cost of the laser driver) are not nearly as critical as technical performance parameters (e.g., mirror reflectivity) in determining wafer exposure costs.
Atoms in very strong magnetic fields

The X-rays spectra of neutron stars are expected to be determined by the opacities of atoms with atomic number Z > 2 in strong magnetic fields. The energy levels, wavefunctions and transitions rates are calculated for hydrogen, carbon, nitrogen and silicon in the very strong (B > 4.7 × 10 9 Z 2 G) magnetic fields expected in neutron stars. The wavefunctions are represented in terms in Landau states, and are calculated with a high-fields multiconfigurational Hartree-Fock code
Pricing for enabling forwarding in self-configuring ad hoc networks

The assumption that all nodes cooperate to relay packets for each other may not be realistic for commercial wireless ad hoc networks. An autonomous (selfish) node in a wireless network has two disincentives for forwarding for others: energy expenditure (real cost) and possible delays for its own data (opportunity cost). We introduce a mechanism that "fosters cooperation through bribery" in the context of forwarding in ad hoc networks. Using a microeconomic framework based on game theory, we design and analyze a pricing algorithm that encourages forwarding among autonomous nodes by reimbursing forwarding. Taking a joint network-centric and user-centric approach, the revenue maximizing network and utility (measured in bits-per-Joule) maximizing nodes interact through prices for channel use, reimbursements for forwarding, transmitter power control, as well as forwarding and destination preferences. In a three-node (two-sources, one-access-point) network, the network converges to an architecture that induces forwarding only when the network geometries are such that forwarding is likely to increase individual benefits (network revenue and node utilities). For other geometries, the network converges to architectures that do not favor forwarding. We then generalize to a multinode network, where it is seen that the nodes' willingness to forward decrease for large ratios of the average internodal distance to the smallest distance between the access point and any source node. Pricing with reimbursement generally improves the network aggregate utility (or aggregate bits-per-Joule), as well as utilities and revenue compared with the corresponding pricing algorithm without reimbursement.
Early cow’s milk introduction is associated with failed personal–social milestones after 1 year of age

Both the American Academy of Pediatrics (AAP) and the Institute of Medicine (IOM) recommend delaying the introduction of cow’s milk until after 1 year of age due to its low absorbable iron content. We used a novel computerized decision support system to gather data from multiple general pediatrics offices. We asked families whether their child received cow’s milk before 1 year of age, had a low-iron diet, or used low-iron formula. Then, at subsequent visits, we performed a modified developmental assessment using the Denver II. We assessed the effect of early cow’s milk or a low-iron diet on the later failure of achieving developmental milestones. We controlled for covariates using logistic regression. Early cow’s milk introduction (odds ratio (OR) 1.30, p = 0.012), as well as a low-iron diet or low-iron formula (OR 1.42, p < 0.001), was associated with increased rates of milestone failure. Only personal–social milestones (OR 1.44, p = 0.002) showed a significantly higher rate of milestone failure. Both personal–social (OR 1.42, p < 0.001) and language (OR 1.22, p = 0.009) showed higher rates of failure in children with a low-iron diet. Conclusions: There is an association between the introduction of cow’s milk before 1 year of age and the rate of delayed developmental milestones after 1 year of age. This adds strength to the recommendations from the AAP and IOM to delay cow’s milk introduction until after 1 year of age.
Every graph has an embedding in $S^3$ containing no non-hyperbolic knot

In contrast with knots, whose properties depend only on their extrinsic topology in S 3 , there is a rich interplay between the intrinsic structure of a graph and the extrinsic topology of all embeddings of the graph in S 3 . For example, it was shown by Conway and Gordon that every embedding of the complete graph K 7 in S 3 contains a non-trivial knot. Later it was shown that for every m E N there is a complete graph K n such that every embedding of K n in S 3 contains a knot Q whose minimal crossing number is at least m. Thus there are arbitrarily complicated knots in every embedding of a sufficiently large complete graph in S 3 . We prove the contrasting result that every graph has an embedding in S 3 such that every non-trivial knot in that embedding is hyperbolic. Our theorem implies that every graph has an embedding in S 3 which contains no composite or satellite knots.
Ergodic Stochastic Optimization Algorithms for Wireless Communication and Networking

Ergodic stochastic optimization (ESO) algorithms are proposed to solve resource allocation problems that involve a random state and where optimality criteria are expressed in terms of long term averages. A policy that observes the state and decides on a resource allocation is proposed and shown to almost surely satisfy problem constraints and optimality criteria. Salient features of ESO algorithms are that they do not require access to the state's probability distribution, that they can handle nonconvex constraints in the resource allocation variables, and that convergence to optimal operating points holds almost surely. The proposed algorithm is applied to determine operating points of an orthogonal frequency division multiplexing broadcast channel that maximize a given rate utility.
The origins of stone tool reduction and the transition to knapping: An experimental approach

Abstract A reassessment of many of the archaeological assemblages older than two million years has resulted in a general consensus that the earliest Oldowan artifacts were made by skilled toolmakers who had a clear understanding of the fracturing mechanics of different toolstone materials. This has led several researchers to propose a simpler lithic reduction stage that occurred prior to 2.6 Ma. Three lithic reduction techniques that are within the behavioral repertoire of our closest living relatives in the genus Pan are proposed as potential intermediate stages between the percussion behaviors of the last common ancestor of chimpanzees and humans and the skilled knapping of the Oldowan toolmakers. These include direct and indirect projectile percussion and bipolar flaking techniques. Measures of productivity, expediency, and efficiency were obtained and compared between these three reduction techniques and novice freehand knapping in order to better understand some of the factors that influenced how early hominins with little to no understanding of lithic fracturing mechanics achieved sharp flake tools. The provisional results of this proof-of-concept experiment indicate that, of these four conditions, dropping or throwing a large hammer stone on a brittle core is the most efficient way to exploit a core, while bipolar flaking is the most expedient method; however, novice freehand knapping creates the most productive flakes with large, sharp cutting edges. Thus, the transition to knapping in the late Pliocene may have been due to a shifting emphasis on productive toolmaking over expediency or efficiency.
Spatial Correlation of Massive Black Hole Mergers: Probing the Formation Mechanism and Reionization

We consider the spatial clustering of massive black hole (MBH) mergers and discuss possible ways to use gravitational wave (GW) observations in the LISA and DECIGO/BBO range for obtaining cosmological and cosmogonical information. Constraints on large-scale structure (LSS) and merger histories may be possible through the detection of an alignment of the GW polarization direction with principal axes of the LSS. Constraints on the merger physics and the reionization epoch may be obtained by GW measurements of MBH correlation lengths, in the case where the MBH angular momentum loss occurs through gas drag. Such measurements would provide information about the LSS and the reionization epoch, as well as about the astrophysics of MBH mergers, in addition to and independent of that obtained from electromagnetic signals.
Culture's Impact on the Importance of Fairness in Interorganizational Relationships

Abstract Research on interorganizational relationships is predicated on the idea that fairness is always important. The authors question this assumption because most fairness research has been conducted in Western countries, and mixed empirical support draws into question how important fairness actually is. Drawing on Hofstede's cultural dimensions framework, the authors examine culture as an antecedent to the importance of outcome fairness (OF) and procedural fairness (PF) in retailers' assessments of their relationships with suppliers. The authors also propose that cultural exposure moderates the impact of culture on fairness importance. Using responses from retailers in ten countries analyzed with hierarchical linear modeling, the authors find that uncertainty avoidance enhances the importance of OF and PF, power distance marginally decreases the importance of PF, and long-term orientation increases the importance of both OF and PF. Cultural exposure also positively moderates the impact of uncertainty ...
Compensation of State-Dependent Input Delay for Nonlinear Systems

We introduce and solve stabilization problems for linear and nonlinear systems with state-dependent input delay. Since the state dependence of the delay makes the prediction horizon dependent on the future value of the state, which means that it is impossible to know a priori how far in the future the prediction is needed, the key design challenge is how to determine the predictor state. We resolve this challenge and establish closed-loop stability of the resulting infinite-dimensional nonlinear system for general non-negative-valued delay functions of the state. Due to an inherent limitation on the allowable delay rate in stabilization of systems with time-varying input delays, in the case of state-dependent delay, where the delay rate becomes dependent on the gradient of the delay function and on the state and control input, only regional stability results are achievable. For forward-complete systems, we establish an estimate of the region of attraction in the state space of the infinite-dimensional closed-loop nonlinear system and for linear systems we prove exponential stability. Global stability is established under a restrictive Lyapunov-like condition, which has to be a priori verified, that the delay rate be bounded by unity, irrespective of the values of the state and input. We also establish local asymptotic stability for locally stabilizable systems in the absence of the delay. Several illustrative examples are provided, including unicycle stabilization subject to input delay that grows with the distance from the reference position.
Effects of Resonant Tesseral Gravity Coefficients on Viking-Type Orbits

A special perturbation technique has been developed for the long-period and secular motion of a Viking-type orbiter. The technique uses a method of singly averaging the perturbations over the mean anomaly to determine changes in orbital elements due to atmospheric drag, solar radiation pressure, solar gravity, and the asymmetrical Mars gravitational field. The technique has been specialized to treat resonant tesseral gravity effects resulting from the commensiirability of the satellite orbit period with the rotational period of the primary. Results are presented which indicate that orbiter lifetimes can be significantly reduced by resonant tesserals for orbits near the critical inclination. Conversely, it is shown that lifetimes can be extended via capture in resonant orbits which are stable against small drag forces.
Cation Radicals in the Synthesis and Reactions of Cyclobutanes

1 Introduction 2 Historical 3 Energetic Considerations for Cation Radical/Neutral Cycloaddition Reactions 4 Novel Cation Radical Structures Encountered in Cation Radical/Neutral Cycloadditions 5 Mechanistic Considerations 6 Stereochemistry of Cation Radical Cyclobutanation 7 Other Early Cation Radical Cyclobutanation Precedents 8 Mechanistic Diversity 9 The Concerted (or Quasi-Concerted) Cycloaddition Mechanism 10 Mechanistic Considerations in Aminium Salt Initiated Cyclobutadimerizations 11 Cross Cyclobutanation 12 Cyclobutane Periselectivity in Cross Additions to Conjugated Dienes 13 The Competition between Cation Radical Cyclobutanation and Diels–Alder Cycloaddition 14 Steric Effects in Cation Radical Cyclobutanation 15 Diels–Alder Periselectivity in Reactions with Acyclic Dienes 16 Diels–Alder/Cyclobutanation Competition in Cation Radical Cycloadditions to Styrenes 17 Conformational Effects upon Periselectivity in Cation Radical/Neutral Cycloaddition Reactions 18 The Cation Radical Vinylcyclobutane (VCB) Rearrangement 19 Stereochemistry of the Cation Radical Vinylcyclobutane Rearrangement 20 The Cation Radical Arylcyclobutane Rearrangement 21 Intramolecular Cation Radical Cyclobutanation 22 Natural Product Synthesis via Cation Radical Cyclobutanation 23 Cation Radical Chain Cycloaddition Polymerization 24 Retrocyclobutanation 25 Cation Radical Cycloadditions Involving Alkynes 26 Cation Radical Chain Reactions of Alkene Cation Radicals with Dioxygen 27 Retroelectrocyclic Reactions of Cyclobutene Cation Radicals Keywords: cyclodimerization of N-vinylcarbazole and photosensitized electron transfer (PET); hole transfer (HT) and electron transfer (ET); cation radical/neutral cycloaddition reactions; nonbonding 2p atomic orbital on carbon (NBAO); cation radical cyclobutanation steric effects; distonic cation radical in Ledwith mechanism; cation radical cyclobutanation stereochemistry; cross cyclobutanation
Ophthalmic antibiotics and antimicrobial resistance a randomized, controlled study of patients undergoing intravitreal injections

Purpose To determine whether repeated exposure of ocular and nasopharyngeal flora to ophthalmic antibiotics promotes antimicrobial resistance in patients undergoing intravitreal injections for choroidal neovascularization (CNV). Design Prospective, randomized, controlled, clinical trial. Participants Forty-eight eyes of 24 patients undergoing unilateral intravitreal injections for CNV. Methods Patients were assigned randomly to 1 of 4 ophthalmic antibiotics (azithromycin 1%, ofloxacin 0.3%, gatifloxacin 0.3%, moxifloxacin 0.5%) to be used after each injection in the treatment eye only. Bilateral conjunctival and unilateral nasopharyngeal cultures on the treatment side were obtained at baseline and were repeated at each subsequent visit for 1 year. All bacterial isolates were tested for antibiotic susceptibility to 16 different antibiotics using the Kirby-Bauer disc diffusion technique. Genetic analysis of bacteria strains was performed using pulse-field gel electrophoresis. Main Outcome Measures Changes in antibiotic susceptibility patterns of conjunctival and nasopharyngeal flora over time and emergence of resistant strains. Results Eight subjects (33%) grew Staphylococcus aureus from the nasopharynx and 1 subject (13%) showed emergence of a resistant strain. Coagulase-negative staphylococci (CNS) cultured from eyes repeatedly exposed to fluoroquinolone antibiotics demonstrated significantly increased rates of resistance to third- and fourth-generation fluoroquinolones compared with untreated eyes. Resistance to ofloxacin and levofloxacin was roughly 85% ( P = 0.003), and resistance to gatifloxacin and moxifloxacin approached 67% ( P = 0.009) and 77% ( P P = 0.009) and decreased resistance to third-generation ( P P Conclusions Repeated exposure of ocular and nasopharyngeal flora to ophthalmic antibiotics selects for resistant strains. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
New approach to remote gas-phase chemical quantification: selected-band algorithm

We propose an algorithm for standoff quantification of chemical vapor plumes from hyperspectral imagery. The approach is based on the observation that the quantification problem can be easily solved in each pixel with the use of just a single spectral band if the radiance of the pixel in the absence of the plume is known. This plume-absent radiance may, in turn, be recovered from the radiance of the subset of spectral bands in which the gas species is transparent. This “selected-band” algorithm is most effective when applied to gases with narrow spectral features, and are therefore transparent over many bands. We also demonstrate an iterative version that expands the range of applicability. Simulations show that the new algorithm attains the accuracy of existing nonlinear algorithms, while its computational efficiency is comparable to that of linear algorithms.
Self-Disclosure as a Predictor of EAP Supervisory Utilization

ABSTRACT The value of Employee Assistance Programs (EAPs) has been cited in a variety of published papers and articles. An important managerial element relative to the assessment and referral of troubled employees has been supervisory training. There have been numerous studies highlighting the various factors and circumstances associated with supervisory behavior and EAP referrals. The inclusion of emotional awareness factors in EAP supervisory utilization has not been thoroughly investigated, although frequently found in the literature as a training and development objective for managers in business and education. The present study provides support for supervisory self-disclosure/self-confrontation as a predictive characteristic among EAP utilizing supervisors and as a viable component for inclusion in future EAP supervisory training efforts as well.
Hamiltonicity in connected regular graphs

In 1980, Jackson proved that every 2-connected k-regular graph with at most 3k vertices is Hamiltonian. This result has been extended in several papers. In this note, we determine the minimum number of vertices in a connected k-regular graph that is not Hamiltonian, and we also solve the analogous problem for Hamiltonian paths. Further, we characterize the smallest connected k-regular graphs without a Hamiltonian cycle.
Broadband Observations and Modeling of the Shell-Type Supernova Remnant G347.3-0.5

The supernova remnant G347.3–0.5 emits a featureless power-law in X-rays, thought to indicate shock-acceleration of electrons to high energies. We here produce a broadband spectrum of the bright NW limb of this source by combining radio observations from the Australia Telescope Compact Array (ATCA), X-ray observations from the Advanced Satellite for Cosmology and Astrophysics (ASCA), and TeV γ-ray observations from the CANGAROO imaging y Cerenkov telescope. We assume this emission is produced by an electron population generated by diffusive shock acceleration at the remnant forward shock. The nonlinear aspects of the particle acceleration force a connection between the widely different wavelength bands and between the electrons and the unseen ions, presumably accelerated simultaneously with the electrons. This allows us to infer the relativistic proton spectrum and estimate ambient parameters such as the supernova explosion energy, magnetic field, matter density in the emission region, and efficiency of the shock acceleration process. We find convincing evidence that the shock acceleration is efficient, placing> 25% of the shock kinetic energy flux into relativistic ions. Despite this high efficiency, the maximum electron and proton energies, while depending somewhat on assumptions for the compression of the magnetic field in the shock, are well below the observed ‘knee’ at ∼ 10 15 eV in the Galactic cosmic-ray spectrum. Subject headings: Supernova remnants — acceleration of particles — cosmic-rays — X-rays — radio — gamma-rays: ISM: individual (G347.3-0.5)
Finding Usability and Communicability Problems for Transactional Web Applications

Today the amount of web applications has grown exponentially and the number of both novice and experienced users decided to experiment with these applications has increased. However, there has been a large increase in problems when the user interacts with those applications. Therefore, a study was made in order to ensure the quality of web applications. To achieve this, a usability methodology for transactional web applications was applied first, where a considerable number of problems identified by Nielsen principles were found and we applied the communicability methods SIM (Semiotic Inspection Method) and CEM (Communicability Assessment Method). During this research two web applications were tested, we found out that there is an association with usability problems, where the 68% to 72% of these problems are about communicability, which turn to be the most serious problems. This shows how difficult is for the designer to interact with the user and vice versa.
Non-abelian duality and canonical transformations

Abstract We construct explicit canonical transformations producing non-abelian duals in principal chiral models with arbitrary group G. Some comments concerning the extension to more general σ-modols, like WZW models, are given.
Mechanistic aspects of CYP74 allene oxide synthases and related cytochrome P450 enzymes

Abstract The existence of CYP5, CYP8A, and the CYP74 enzymes specialized for reaction with fatty acid peroxide substrates presents opportunities for a “different look” at the catalytic cycle of the cytochrome P450s. This review considers how the properties of the peroxide-metabolizing enzymes are distinctive, and how they tie in with those of the conventional monooxygenase enzymes. Some unusual reactions of each class have parallels in the other. As enzyme reactions and P450 structures emerge there will be possibilities for finding their special properties and edging this knowledge into the big picture.
The Surface of Mars

Our knowledge of Mars has grown enormously over the last decade as a result of the Mars Global Surveyor, Mars Odyssey, Mars Express, and the two Mars Rover missions. This book is a systematic summary of what we have learnt about the geological evolution of Mars as a result of these missions. It describes the diverse Martian surface features and summarizes current ideas as to how, when, and under what conditions they formed, and explores how Earth and Mars differ and why the two planets evolved so differently. The author also discusses possible implications of the geologic history for the origin and survival of indigenous Martian life. Up-to-date and highly illustrated, this book will be a principal reference for researchers and graduate students in planetary science. The comprehensive list of references will also assist readers in pursuing further information on the subject. Colour images can be found at www.cambridge.org/9780521872010.
Spectral gaps for sets and measures

If X is a closed subset of the real line, denote by GX the supremum of the size of the gap in the Fourier spectrum of a measure, taken over all non-trivial finite complex measures supported on X. In this paper we attempt to find GX in terms of X.
Complicated dynamics in spacecraft attitude control systems

It is shown that a commonly used, momentum exchange, spacecraft attitude control configuration gives rise to complex nonlinear behavior involving multiple limit cycles and strange attractors. However, if the momentum wheel assembly performance parameters are adequately matched to the spacecraft it is possible to achieve a globally stable equilibrium. The results are based on the analysis of a simple single axis problem.
Elasticity of uncrosslinked rubbers

Abstract Recovery from a prior deformation has been shown to follow simple general laws, which are readily extrapolated to molding or extrusion temperatures. They are also in principle applicable to more complex deformations and deformation histories.
An innovative method to determine percutaneous absorption: Real-time breath analysis and physiologically based pharmacokinetic modeling

From the 1950s through the 1970s, the rate of uptake of a chemical through the skin was generally estimated from studies of humans using radiolabeled compounds [1]. More recently, estimates of derm...
Evaluation of Surgical Staples for Ligation of the Renal Pedicle During Nephrectomy

A mechanical stapling instrument was evaluated for ligation of the renal pedicle during nephrectomy in nine healthy sheep. Two forms of disposable loading unit, from which stainless steel surgical staples could be dispensed in double or triple staggered row configuration, were assessed for their proper function when applied across the renal pedicle singularly or in series. The response of the sheep to surgery was assessed by physical, hematological, and serum chemistry evaluations. Tissue healing was determined by gross and histopathological examinations. Ligation and transection of the pedicle took 2 to 4 minutes. The vessels of the pedicle ranged in diameter from 3 to 12 mm. In two sheep, overzealous stripping of perivascular tissue from the renal pedicle prior to placement of a triple staggered row of staples resulted in mild hemorrhage from the renal stump. This was controlled by placing a second triple staggered row of staples proximal to the first. It was concluded that ligation of the renal pedicle could be performed rapidly, effectively, and safely in healthy sheep using the correctly applied mechanical stapler. It is inferred that a similar technique would be applicable to other species including man.
Total synthesis of (+/-)-lepadiformine via an amidoacrolein cycloaddition.

The total synthesis of the cytotoxin lepadiformine is described. The intermolecular cycloaddition of a 2-amidoacrolein with the dimethyl acetal of 4,6-heptadienal gave a cycloadduct that was strategically functionalized for elaboration of the tricyclic ring system. These steps include a diastereoselective addition of an organoytterbium reagent to an aldehyde, cyclization to the trans-perhydroquinoline substructure via a Mitsunobu reaction, and an iodine-promoted amine cyclization with an alkene to introduce the pyrrolidine ring.
What is the gravity dual of a chiral primary

Abstract In the AdS/CFT correspondence a chiral primary is described by a string theory solution with mass equaling angular momentum. For AdS 3 × S 3 we are led to consider three special families of metrics with this property: metrics with conical defects, Aichelburg–Sexl type metrics generated by rotating particles, and metrics generated by giant gravitons. We find that the first two of these are special cases of the complete family of chiral primary metrics which can be written down using the general solution in hep-th/0109154 , but they correspond to two extreme limits—the conical defect metrics map to CFT states generated by twist operators that are all identical, while the Aichelburg–Sexl metrics yield a wide dispersion in the orders of these twists. The giant graviton solutions in contrast do not represent configurations of the D1–D5 bound state; they correspond to fragmenting this system into two or more pieces. We look at the large distance behavior of the supergravity fields and observe that the excitation of these fields is linked to the existence of dispersion in the orders and spins of the twist operators creating the chiral primary in the CFT.
The Low Quiescent X-Ray Luminosity of the Neutron Star Transient XTE J2123–058

We report on the first X-ray observations of the neutron star soft X-ray transient (SXT) XTE J2123-058 in quiescence made by the Chandra X-Ray Observatory and BeppoSAX, as well as contemporaneous optical observations. In 2002, the Chandra spectrum of XTE J2123-058 is consistent with a power-law model or the combination of a blackbody plus a power law, but it is not well described by a pure blackbody. Using the interstellar value of NH, the power-law fit gives Γ = 3.1 and indicates an 0.3-8 keV unabsorbed luminosity of 9 × 1031(d/8.5 kpc)2 ergs s-1 (90% confidence errors). Fits with models consisting of thermal plus power-law components indicate that the upper limit on the temperature of a 1.4 M☉, 10 km radius neutron star with a hydrogen atmosphere is kTeff < 66 eV, and the upper limit on the unabsorbed, bolometric luminosity is L∞ < 1.4 × 1032 ergs s-1, assuming d = 8.5 kpc. Of the neutron star SXTs that exhibit short (<1 yr) outbursts, including Aql X-1, 4U 1608-522, Cen X-4, and SAX J1810.8-2609, the lowest temperatures and luminosities are found for XTE J2123-058 and SAX J1810.8-2609. From the BeppoSAX observation of XTE J2123-058 in 2000, we obtained an upper limit on the 1-10 keV unabsorbed luminosity of 9 × 1032 ergs s-1. Although this upper limit allows for the X-ray luminosity to have decreased between 2000 and 2002, that possibility is not supported by our contemporaneous R-band observations, which indicate that the optical flux increased significantly. Motivated by the theory of deep crustal heating by Brown and coworkers, we characterize the outburst histories of the five SXTs. The low quiescent luminosity for XTE J2123-058 is consistent with the theory of deep crustal heating without requiring enhanced neutron star cooling if the outburst recurrence time is 70 yr.
Semiclassical Cauchy estimates and applications

In this note, we study solutions to semiclassical Schrodinger equations on a real analytic manifold with a real analytic potential and prove the semiclassical version of Cauchy estimates on derivatives. As an application, we use Donnelly and Fefferman's method to prove the upper and lower bounds for (n-1)-dimensional Hausdorff measure of the nodal sets of the solutions to semiclassical Schrodinger equations.
Identifying Causal Marketing Mix Effects Using a Regression Discontinuity Design

We discuss how regression discontinuity designs arise naturally in settings where firms target marketing activity at consumers, and we illustrate how this aspect may be exploited for econometric inference of causal effects of marketing effort. Our main insight is to use commonly observed discontinuities and kinks in the heuristics by which firms target such marketing activity to consumers for nonparametric identification. Such kinks, along with continuity restrictions that are typically satisfied in marketing and industrial organization applications, are sufficient for identification of local treatment effects. We review the theory of regression discontinuity estimation in the context of targeting and explore its applicability to several marketing settings. We discuss identifiability of causal marketing effects using the design and show that consideration of an underlying model of strategic consumer behavior reveals how identification hinges on model features such as the specification and value of structural parameters as well as belief structures. We emphasize the role of selection for identification. We present two empirical applications: the first measures the effect of casino e-mail promotions targeted to customers based on ranges of their expected profitability, and the second measures the effect of direct mail targeted by a business-to-consumer company to zip codes based on cutoffs of expected response. In both cases, we illustrate that exploiting the regression discontinuity design reveals negative effects of the marketing campaigns that would not have been uncovered using other approaches. Our results are nonparametric, easy to compute, and control for the endogeneity induced by the targeting rule.
A generalization of Dirichlet's unit theorem

We generalize Dirichlet’s S-unit theorem from the usual group of S-units of a number field K to the infinite rank group of all algebraic numbers having nontrivial valuations only on places lying over S. Specifically, we demonstrate that the group of algebraic S-units modulo torsion is a Q-vector space which, when normed by the Weil height, spans a hyperplane determined by the product formula, and that the elements of this vector space which are linearly independent over Q retain their linear independence over R.
p53 Sequence Analysis Predicts Treatment Response and Outcome of Patients with Esophageal Carcinoma

BACKGROUND. The ability to predict biologic behavior and treatment responsiveness would be a valuable asset in the multimodality approach to esophageal carcinoma. The authors examined whether alterations of the p53 gene correlate with clinicopathologic parameters, response to preoperative chemotherapy/radiotherapy, and outcome in patients with esophageal carcinoma. METHODS. Histopathologic/genetic analysis of p53 was performed on formalin fixed, paraffin embedded tissues. Tissue sections were stained immunohistochemically for p53 protein followed by topographic genotyping comprised of polymerase chain reaction amplification and direct sequencing of p53 exons 5‐ 8. All patients received induction chemotherapy (5-fluorouracil, cisplatin, and a-interferon) and concurrent external beam radiotherapy (4500 centigrays) followed by resection. RESULTS. p53 analysis performed on 42 tumors from patients with potentially resectable esophageal carcinoma revealed 25 of the 42 tumors (59.5%) to be p53 immunopositive; however, only 17 of the 42 tumors (40.5%) were proven to contain p53 point mutational damage in exons 8 (n 5 5), 5( n5 5), 7( n5 4), and 6 (n 5 3). Eight cases were weakly immunopositive and had no genotype mutation suggesting hyperexpression of normal wild-type p53. Genotyping also identified two immunonegative cases with deletion-type mutations (exons 5 and 6). Tissue samples collected before and after chemotherapy/radiotherapy exhibited fidelity in p53 mutational genotype in all cases. The presence of a p53 point mutation positively correlated with pTNM stage (P 5 0.003) and residual disease in the resected specimen (P 5 0.01). Moreover, survival of patients with p53 mutations was significantly lower than that of patients without mutations (overall survival of 21.6 months vs. 40 months; P 5 0.0038; and disease free survival of 14.1 months vs. 38 months; P 5 0.0004). CONCLUSIONS. Histopathologic/genetic analysis is a better determinant of p53 mutational damage than immunohistochemistry alone and can be used as a prognostic marker for esophageal carcinoma. p53 genotyping may define a subset of patients who respond to chemotherapy/radiotherapy and may predict who potentially benefits from multimodality therapy. Cancer 1998;83:7‐18. © 1998 American Cancer Society.
Fast and Controllable Simulation of the Shattering of Brittle Objects

We present a method for the rapid and controllable simulation of the shattering of brittle objects under impact. An object is represented as a set of point masses connected by distance-preserving linear constraints. This use of constraints, rather than stiff springs, gains us a significant advantage in speed while still retaining fine control over the fracturing behavior. The forces exerted by these constraints during impact are computed using Lagrange multipliers. These constraint forces are then used to determine when and where the object will break, and to calculate the velocities of the newly created fragments. We present the details of our technique together with examples illustrating its use. An earlier version of this paper was presented at Graphics Interface 2000, held in Montreal, Canada.