cssi/SciSciGPT-SciSciNet huggingface dataset:
Rollovers on sideslopes and ditches

National data were analyzed to define the nature and importance of the problem of ran-off-road vehicles that rollover on slopes and ditches. Also, data from two specialized data bases were used to obtain insight on vehicle orientation and driver maneuvers in such crashes. This crash type was found to be the leading cause of ran-off-road driver fatalities, accounting for about one-fourth of this total. Highway factors associated with this crash type are identified to assist in the effort to define specific roadway locations where highway design countermeasures may be appropriate. Specifically, attention should be given to the outside of horizontal curves on rural two-lane roads. Vehicle dynamics computer simulations appear to offer the most promising approach to obtain needed insight on rollover risks for specific slope and ditch geometric combinations. Vehicle trajectory information found in this study should be useful in the design and interpretation of needed follow-on simulation studies. Vehicle trajectories in slope rollovers were found to be both different from, and more complex than, fixed object crashes.
Coexistence between superconducting and spin density wave states in iron-based superconductors: Ginzburg–Landau analysis

We consider the interplay between superconducting (SC) and commensurate spin-density-wave (SDW) orders in iron pnictides by analyzing a multiple-order Ginzburg–Landau free energy. We are particularly interested in whether the doping-induced transition between the two states is first order or whether the two pure phases are separated by an intermediate phase with coexisting SC and SDW orders. For perfect nesting, the two orders do not coexist, because SDW order, which comes first, gaps the full Fermi surface leaving no space for SC to develop. When nesting is not perfect due to either ellipticity of electron bands or doping-induced difference in chemical potentials for holes and electrons, SDW order still leaves modified Fermi surfaces for not too strong SDW magnetism and the SC order may develop. We show that the two orders coexist only when certain relations between ellipticity and doping are met. In particular, in a compensated metal, ellipticity alone is not sufficient for coexistence of the two orders.
A note on percolation on $Z^d$: isoperimetric profile via exponential cluster repulsion

We show that for all $p>p_c(\mathbb{Z}^d)$ percolation parameters, the probability that the cluster of the origin is finite but has at least $t$ vertices at distance one from the infinite cluster is exponentially small in $t$. We use this to give a short proof of the strongest version of the important fact that the isoperimetric profile of the infinite cluster basically coincides with the profile of the original lattice. This implies, e.g., that simple random walk on the largest cluster of a finite box $[-n,n]^d$ with high probability has $L^\infty$-mixing time $\Theta(n^2)$, and that the heat kernel (return probability) on the infinite cluster a.s. decays like $p_n(o,o)=O(n^{-d/2})$. Versions of these results have been proven by Benjamini and Mossel (2003), Mathieu and Remy (2004), Barlow (2004) and Rau (2006). For general infinite graphs, we prove that anchored isoperimetric properties survive supercritical percolation, provided that the probability of the cluster of the origin being finite with large boundary decays rapidly; this is the case for a large class of graphs when $p$ is close to 1. As an application (with the help of some entropy inequalities), we give a short conceptual proof of a theorem of Angel, Benjamini, Berger and Peres (2006): the infinite percolation cluster of a wedge in $\mathbb{Z}^3$ is a.s. transient whenever the wedge itself is transient.
The stages of economic growth

This third edition of The Stages of Economic Growth, first published in 1991, has a new preface and appendix, Professor Rostow extends his analysis to include economic and political developments as well as the advances in theory concerning nonlinear and chaotic phenomena. For those coming to his work for the first time, the original text and the introductions and appendices from earlier editions are included. This volume will not only be of interest to those concerned with the theory of economic growth, but also to students of policy since the 1960s. In the text Professor Rostow gives an account of economic growth based on a dynamic theory of production and interpreted in terms of actual societies. Five basic stages of economic growth are distinguished with detailed discussions of each stage including illustrative examples. He also applies the concept of stages of growth to an examination of the problems of military aggression and the nuclear arms race. The final chapter includes a comparison of his non-communist manifesto with Marxist theory. Materials from the second edition include an appendix in which he responds to some of his critics.
Is there a role for reconstructive techniques to prevent periodontal defects after third molar surgery

In the previous article, a comprehensive review of the literature suggests that the periodontal status on the distal of the mandibular second molar (M2) is unchanged or improved after extraction of the adjacent mandibular third molar (M3). In looking critically at the postoperative probing depths (PDs) or attachment levels (ALs), despite improvement over the preoperative condition, there still may be persistent periodontal defects. This finding begs the question: ‘‘Do other interventions need to be applied at the time of M3 removal to enhance the periodontal outcomes after M3 extraction?’’ Converting the information needs to an evidence-based clinical question results in the following question: ‘‘Among subjects undergoing mandibular M3 removal, does intervention at the time of tooth removal, when compared with no intervention, improve the long-term periodontal health on the distal aspect of the adjacent M2?’’ A review of the literature, outlined in the
Graded Skew Clifford Algebras That Are Twists of Graded Clifford Algebras

In 2010, a quantized analog of a graded Clifford algebra (GCA), called a graded skew Clifford algebra (GSCA), was proposed by Cassidy and Vancliff, and many properties of GCAs were found to have counterparts for GSCAs. In particular, a GCA is a finite module over a certain commutative subalgebra C, while a GSCA is a finite module over a (typically noncommutative) analogous subalgebra R. We consider the case that a regular GSCA is a twist of a GCA by an automorphism, and we prove, in this case, R is a skew polynomial ring and a twist of C by an automorphism.
Management of inverted papillomas of the nose and paranasal sinuses.

Abstract Purpose Inverted papillomas (IPs), although histologically benign, are aggressive lesions that may recur after an excision. The objective of this study was to compare the surgical treatment options for IPs with an emphasis on the experience of our institution with midfacial degloving (MFD) and medial maxillectomy. Materials and Methods A retrospective review of the charts of patients with IP treated by MFD and medial maxillectomy was performed. An analysis of the recurrence rates of IPs in the literature for endoscopic surgery and lateral rhinotomy was also performed. Results Ninety-eight medial maxillectomy procedures via MFD were performed for IPs with a minimum of 2 years' follow-up (median = 5.1 years). Two patients were found to have recurrences (2.1%). The literature review revealed an average recurrence rate of 15.7% for lateral rhinotomy as compared with that of 19.6% for endoscopic surgery. Conclusion Midfacial degloving balances acceptable cosmetic results with low recurrence rates. It allows for adequate exposure and resection without the scar of a lateral rhinotomy incision.
Enzymatic synthesis of N-acylethanolamines: direct method for the aminolysis of esters

Abstract Immobilized Candida antarctica (Novozyme 435) catalyzed synthesis of N -acylethanolamines is described. Treatment of methyl esters with lipase and amines yielded the desired amides within 2–24 h with yields ranging from 41% to 98%.
Tensor Glueball-Meson Mixing Phenomenology

The overpopulated isoscalar tensor states are sifted using Schwinger–type mass relations. Two solutions are found: one where the glueball is the \(f_J(2220)\), and one where the glueball is more distributed, with \(f_2(1820)\) having the largest component. The \(f_2(1565)\) and \(f_J(1710)\) cannot be accommodated as glueball–(hybrid) meson mixtures in the absense of significant coupling to decay channels. \(f_2'(1525)\rightarrow\pi\pi\) is in agreement with experiment. The \(f_J(2220)\) decays neither flavour democratically nor is narrow.
Polarization characteristics of synchrotron radiation sources and a new two undulator system

Abstract The polarization properties of the usual synchrotron radiation sources, bending magnets, wigglers and undulators, are briefly reviewed. The recently proposed two undulator system can provide synchrotron radiation with arbitrarily adjustable polarization. The characteristics of this device, both as a source of spontaneous radiation and also as a free electron laser system, are discussed.
Cluster before you hallucinate: approximating node-capacitated network design and energy efficient routing

We consider circuit routing with an objective of minimizing energy, in a network of routers that are speed scalable and that may be shutdown when idle. It is known that this energy minimization problem can be reduced to a capacitated flow network design problem, where vertices have a common capacity but arbitrary costs, and the goal is to choose a minimum cost collection of vertices whose induced subgraph will support the specified flow requirements. For the multicast (single-sink) capacitated design problem we give a polynomial-time algorithm that is O(log3 n)- approximate with O(log4 n) congestion. This translates back to a O(log4α+3 n)-approximation for the multicast energy-minimization routing problem, where α is the polynomial exponent in the dynamic power used by a router. For the unicast (multicommodity) capacitated design problem we give a polynomial-time algorithm that is O(log5 n)-approximate with O(log12 n) congestion, which translates back to a O(log12α+5 n)-approximation for the unicast energy-minimization routing problem.
Delays and the Capacity of Continuous-Time Channels

Any physical channel of communication offers two potential reasons why its capacity (the number of bits it can transmit in a unit of time) might be unbounded: (1) (Uncountably) infinitely many choices of signal strength at any given instant of time, and (2) (Uncountably) infinitely many instances of time at which signals may be sent. However channel noise cancels out the potential unboundedness of the first aspect, leaving typical channels with only a finite capacity per instant of time. The latter source of infinity seems less extensively studied. A potential source of unreliability that might restrict the capacity also from the second aspect is ``delay'': Signals transmitted by the sender at a given point of time may not be received with a predictable delay at the receiving end. In this work we examine this source of uncertainty by considering a simple discrete model of delay errors. In our model the communicating parties get to subdivide time as microscopically finely as they wish, but still have to cope with communication delays that are macroscopic and variable. The continuous process becomes the limit of our process as the time subdivision becomes infinitesimal. We taxonomize this class of communication channels based on whether the delays and noise are stochastic or adversarial, and based on how much information each aspect has about the other when introducing its errors. We analyze the limits of such channels and reach somewhat surprising conclusions: The capacity of a physical channel is finitely bounded only if at least one of the two sources of error (signal noise or delay noise) is adversarial. In particular the capacity is finitely bounded only if the delay is adversarial, or the noise is adversarial and acts with knowledge of the stochastic delay. If both error sources are stochastic, or if the noise is adversarial and independent of the stochastic delay, then the capacity of the associated physical channel is infinite!
Physical picture of the gapped excitation spectrum of the one-dimensional Hubbard model

Abstract A simple picture for the spectrum of the one-dimensional Hubbard model is presented using a classification of the eigenstates based on an intuitive bound-state Bethe-ansatz approach. This approach allows us to prove a “string hypothesis” for complex momenta and derive an exact formulation of the Bethe-ansatz equations including all states. Among other things we show that all gapped eigenstates have the Bethe-ansatz form, contrary to assertions in the literature [Essler et al., Nucl. Phys. B 372 (1992) 559]. The simplest excitations in the upper Hubbard band are computed: we find an unusual dispersion close to half-filling.
Design and Characterization of MEMS Micromirrors for Ion-Trap Quantum Computation

To build a large-scale quantum information processor (QIP) based on trapped ions or neutral atoms, integrated optical systems capable of delivering laser beams to multiple target locations are necessary. We consider a beam-shifting element consisting of a tilting micromirror located at the focal point of a lens, as a fundamental building block for such a system. We explore the design space of the micromirrors and characterize their dc, frequency, and transient responses. The fastest mirror features the resonant frequency of 113 kHz and the 98% settling time of 11 mus. The design tradeoffs are discussed to facilitate further optimization of the mirror performance for this application
Tritium AMS for biomedical applications

Abstract We are developing 3H AMS to measure 3H activity of mg-sized biological samples. LLNL has already successfully applied 14C AMS to a variety of problems in the area of biomedical research. Development of 3H AMS would greatly complement these studies. The ability to perform 3H AMS measurements at sensitivities equivalent to those obtained for 14C will allow us to perform experiments using compounds that are not readily available in C-tagged form. A 3H capability would also allow us to perform unique double-labeling experiments in which we learn the fate, distribution, and metabolism of separate fractions of biological compounds.
Suppressing Cracking in Resistance Welding AA5754 by Mechanical Means

In this paper mechanical aspects of cracking during single- and multi-spot welding of AA5754 was investigated by both experimental and analytical approaches. The impact of mechanical loading on crack initiation and propagation was studied with the consideration of various process parameters including the loading imposed by electrodes, the formation of liquid nugget, and constraining factors during and after welding. Tensile properties of AA5754 and their dependence on the temperature were tested at room and up to solidus temperatures, in order to provide a reference of cracking stress. Thermalmechanical analysis was conducted based on the temperature field around the nugget and the state of stress encountered during welding. This analysis revealed that tensile stress might build up in the vicinity of the nugget during cooling, as explained in the experimental observation. General guidelines for suppressing cracking were proposed, i.e., to provide sufficient constraint around the weld spot during and after welding. @DOI: 10.1115/1.1418693#
Procedures for generating gamma variates with non-integer parameter sets

One of the most useful distributions in stochastic modeling is the two parameter gamma distribution. This paper presents a technique for generating random gamma variates from any two parameter gamma form with either integer or non-integer parameters. Only two techniques are presently available for generating gamma variates with a non-integer scale parameter, those being a variate averaging technique proposed by Naylor, et al. and a rejection scheme proposed by Johnk. The three generation schemes are compared with respect to (1) statistical goodness of fit, (2) computer running time and (3) random number calls. The author's scheme is shown to be statistically comparable with respect to goodness of fit, and generaliy superior relevant to computer running times and random number calls.
Supersonic Jet Noise Reductions Predicted With Increased Jet Spreading Rate

In this paper, predictions are made of noise radiation from single, supersonic, axisymmetric jets. We examine the effects of changes in operating conditions and the effects of simulated enhanced mixing that would increase the spreading rate of the jet shear layer on radiated noise levels. The radiated noise in the downstream direction is dominated by mixing noise and, at higher speeds, it is well described by the instability wave noise radiation model. Further analysis with the model shows a relationship between changes in spreading rate due to enhanced mixing and changes in the far field radiated peak noise levels. The calculations predict that enhanced jet spreading results in a reduction of the radiated peak noise level.
In the Business of Dying: Questioning the Commercialization of Hospice

This article critically questions the commercialization of hospice care and the ethical concerns associated with the industry's movement toward "market-driven medicine" at the end of life. For example, the article examines issues raised by an influx of for-profit hospice providers whose business model appears at its core to have an ethical conflict of interest between shareholders doing well and terminal patients dying well. Yet, empirical data analyzing the experience of patients across the hospice industry are limited, and general claims that end-of-life patient care is inferior among for-profit providers or even that their business practices are somehow unseemly when compared to nonprofit providers cannot be substantiated. In fact, non-profit providers are not immune to potentially conflicting concerns regarding financial viability (i.e., "no margin, no mission"). Given the limitations of existing empirical data and contrasting ideological commitments of for-profit versus non-profit providers, the questions raised by this article highlight important areas for reflection and further study. Policymakers and regulators are cautioned to keep ethical concerns in the fore as an increasingly commercialized hospice industry continues to emerge as a dominant component of the U.S. health care system. Both practitioners and researchers are encouraged to expand their efforts to better understand how business practices and commercial interests may compromise the death process of the patient and patient's family--a process premised upon a philosophy and ethical tradition that earlier generations of hospice providers and proponents established as a trusted, end-of-life alternative.
Echo in optical lattices: Stimulated revival of breathing oscillations

We analyze a stimulated revival (echo) effect for the breathing modes of atomic oscillations in optical lattices. The effect arises from the dephasing due to the weak anharmonicity being partly reversed in time by means of additional parametric excitation of the optical lattice. The shape of the echo response is obtained by numerically simulating the equation of motion for the atoms with subsequent averaging over the thermal initial conditions. A qualitative analysis of the phenomenon shows that the suggested echo mechanism combines the features of both spin and phonon echoes.
Adult bone marrow stromal cell-based tissue-engineered aggrecan exhibits ultrastructure and nanomechanical properties superior to native cartilage

Summary Objective To quantify the structural characteristics and nanomechanical properties of aggrecan produced by adult bone marrow stromal cells (BMSCs) in peptide hydrogel scaffolds and compare to aggrecan from adult articular cartilage. Design Adult equine BMSCs were encapsulated in 3D-peptide hydrogels and cultured for 21 days with TGF-β1 to induce chondrogenic differentiation. BMSC-aggrecan was extracted and compared with aggrecan from age-matched adult equine articular cartilage. Single molecules of aggrecan were visualized by atomic force microcopy-based imaging and aggrecan nanomechanical stiffness was quantified by high resolution force microscopy. Population-averaged measures of aggrecan hydrodynamic size, core protein structures and CS sulfation compositions were determined by size-exclusion chromatography, Western analysis, and fluorescence-assisted carbohydrate electrophoresis (FACE). Results BMSC-aggrecan was primarily full-length while cartilage-aggrecan had many fragments. Single molecule measurements showed that core protein and GAG chains of BMSC-aggrecan were markedly longer than those of cartilage-aggrecan. Comparing full-length aggrecan of both species, BMSC-aggrecan had longer GAG chains, while the core protein trace lengths were similar. FACE analysis detected a ∼1:1 ratio of chondroitin-4-sulfate to chondroitin-6-sulfate in BMSC-GAG, a phenotype consistent with aggrecan from skeletally-immature cartilage. The nanomechanical stiffness of BMSC-aggrecan was demonstrably greater than that of cartilage-aggrecan at the same total sGAG (fixed charge) density. Conclusions The higher proportion of full-length monomers, longer GAG chains and greater stiffness of the BMSC-aggrecan makes it biomechanically superior to adult cartilage-aggrecan. Aggrecan stiffness was not solely dependent on fixed charge density, but also on GAG molecular ultrastructure. These results support the use of adult BMSCs for cell-based cartilage repair.
Optimization of Shared High-Performance Reconfigurable Computing Resources

In the field of high-performance computing, systems harboring reconfigurable devices, such as field-programmable gate arrays (FPGAs), are gaining more widespread interest. Such systems range from supercomputers with tightly coupled reconfigurable hardware to clusters with reconfigurable devices at each node. The use of these architectures for scientific computing provides an alternative for computationally demanding problems and has advantages in metrics, such as operating cost/performance and power/performance. However, performance optimization of these systems can be challenging even with knowledge of the system’s characteristics. Our analytic performance model includes parameters representing the reconfigurable hardware, application load imbalance across the nodes, background user load, basic message-passing communication, and processor heterogeneity. In this article, we provide an overview of the analytical model and demonstrate its application for optimization and scheduling of high-performance reconfigurable computing (HPRC) resources. We examine cost functions for minimum runtime and other optimization problems commonly found in shared computing resources. Finally, we discuss additional scheduling issues and other potential applications of the model.
Tests for spatial lag dependence based on method of moments estimation

Abstract In this paper, we formulate GMM versions of the Wald, the Likelihood ratio and the Lagrange multiplier test statistics for spatial lag dependence in the spatial lag model with autocorrelated errors. The tests are based on the GMM estimator suggested by Kelejian and Robinson [Papers in Regional Science: J. RSAI 72 (1993) 297] and on the work of Newey and West [Int. Econ. Rev. 28 (1987) 777]. We analyze their finite-sample properties in a Monte Carlo experiment along with those of two alternative tests for spatial lag dependence based on least squares and generalized least squares estimation, respectively. Results indicate that the small sample distribution of the GMM tests is well approximated by their asymptotic chi-squared distribution for relatively small sample sizes, but only for small values of the spatial error parameter. However, we find variations across different spatial weighting schemes for given sample size and given values of the spatial error parameter.
Circulation controlled STOL wing optimization

By replacing the sharp trailing edge of an airfoil with a rounded Coanda surface, one can generate high lift at a moderate blowing rate. In such a circulation controlled (CC) airfoil, a two-dimensional wall jet is used to force the rear stagnation point down and increase the circulation and lift. The CC airfoil performance and blowing power requirements depend on both the wall jet momentum and the wall jet to freestream velocity ratio because a significant portion of the wall jet momentum is lost to shear over the Coanda surface. When using highpressure jet engine bleed air, an internal wall jet ejector can be used to optimize the wall jet velocity. This will reduce the required bleed airflow rate and cool the wing structure, in addition to providing boundary-layer control by suction. The applicability of CC high lift generation for short takeoff and landing aircraft was first demonstrated at West Virginia University in April 1974 with the WVU CC Technology Demonstrator STOL Aircraft. A second such CC technology demonstrator, a modified Navy A-6A was test flown five years later. The importance of optimizing the wall jet velocity is analyzed in this paper.
Near Infrared Imaging of the Hubble Deep Field with the Keck Telescope

Two deep K-band (2.2 micrometer) images, with point-source detection limits of K=25.2 mag (one sigma), taken with the Keck Telescope in subfields of the Hubble Deep Field, are presented and analyzed. A sample of objects to K=24 mag is constructed and V(sub 606)- I(sub 814) and I(sub 814)-K colors are measured. By stacking visually selected objects, mean I(sub 814)-K colors can be measured to very faint levels, the mean I(sub 814)-K color is constant with apparent magnitude down to V(sub 606)=28 mag.
Feedback Particle Filter

The feedback particle filter introduced in this paper is a new approach to approximate nonlinear filtering, motivated by techniques from mean-field game theory. The filter is defined by an ensemble of controlled stochastic systems (the particles). Each particle evolves under feedback control based on its own state, and features of the empirical distribution of the ensemble. The feedback control law is obtained as the solution to an optimal control problem, in which the optimization criterion is the Kullback-Leibler divergence between the actual posterior, and the common posterior of any particle. The following conclusions are obtained for diffusions with continuous observations: 1) The optimal control solution is exact: The two posteriors match exactly, provided they are initialized with identical priors. 2) The optimal filter admits an innovation error-based gain feedback structure. 3) The optimal feedback gain is obtained via a solution of an Euler-Lagrange boundary value problem; the feedback gain equals the Kalman gain in the linear Gaussian case. Numerical algorithms are introduced and implemented in two general examples, and a neuroscience application involving coupled oscillators. In some cases it is found that the filter exhibits significantly lower variance when compared to the bootstrap particle filter.
Total synthesis of (S,S)-isodityrosine

Abstract The novel dimeric amino acid isodityrosine 1 has been synthesized by a route which uses a new method of diaryl ether preparation. Nucleophilic addition of a protected tyrosine to cyclohexenone oxide and the Pd(0)-catalyzed coupling of an aryl iodide with a protected iodoalanine derivative are the key steps in this synthesis. This represents one of the first efficient syntheses of this molecule beginning with two naturally-occurring amino acids as inexpensive starting materials
Inertia and Energy Effects in the Developing Gas Film Between Two Parallel Flat Plates

Abstract : Inertia and temperature effects in entrance flow between parallel flat plates are investigated by using both boundary layer theory and an approximate analysis. The approximate theory is implemented by a gas table similar to those for conventional Fanno-line computations. (Author)
Skylab Eva System Development

EVA hardware design is traced from initial conceptual development to final flight configuration. Major concepts considered during design evolution are identified, and reasons for the acceptance or rejection of these concepts are discussed. An iterative approach to simulations and testing was found useful. Early conceptual efforts concentrated on analyses and normal gravity, low-cost, low-fidelity mockups; later design phases combined normal gravity and neutral buoyancy simulations of increasing fidelity. Restudying after each change consistently drove EVA hardware toward operational and mechanical simplicity.-
A Multidisciplinary Approach to Orbital Neoplasm

The patient with orbital and periorbital neoplasia requires careful assessment of the extent and biologic activity as well as histopathologic categorization. Treatment is optimal through a multidisciplinary approach involving the ophthalmic surgeon, plastic surgeon, neurosurgeon, head and neck surgeon, and oral surgeon.
Congestion, Land Use, and Job Dispersion: A General Equilibrium Model

Abstract In dispersed cities, congestion tolls would drive up central wages and rents and would induce centrally located producers to want to disperse closer to their workers and their customers, paying lower rents and realizing productivity gains from land to labor substitution. But the tolls would also induce residents to want to locate more centrally in order to economize on commuting and shopping travel. In a computable general equilibrium model, we find that the centralizing effect of tolls on residences dominates on the decentralizing effect of tolls on firms, causing the dispersed city to have more centralized job and population densities. Under stylized parameters, we find that efficiency gains from levying congestion tolls on work and shopping travel are 3.0% of average income. About 80% of such gains come from road planning and 20% from tolls.
Black market exchange rate, currency substitution and the demand for money in LDCs

Abstract Mundell's conjecture in 1963 that the demand for money could depend on the exchange rate in addition to income and interest rate has received some attention in the literature by including the official exchange rate and estimating the money demand in a few developed countries. In less developed countries, since there is a black market for foreign exchange, it has been suggested that the black market exchange rate rather than the official rate should be the determinant of the demand for money in LDCs. This proposition is tested by estimating the demand for money for 25 LDCs using the bounds testing approach to cointegration. The main conclusion is that while in some LDCs, the black market rate enters into the formulation of the demand for money, in some others the official rate is the determinant. The black market premium also played a role in some countries.
Formation of the Antarctic ozone hole by the ClO dimer mechanism

New measurements of the low-altitude ClO profile, made during September 1987, are presented along with detailed observations of ozone depletion over McMurdo Station, Antarctica during the same period. The results show that both the rate and altitude range of ozone depletion can be quantitatively accounted for by a mechanism in which the ClO dimer is the important intermediary in the catalytic destruction of ozone. An alternative bromine mechanism appears capable of contributing only 5-15 percent to the ozone loss rate.
Infected Renal Artery Pseudoaneurysm and Mycotic Aortic Aneurysm After Percutaneous Transluminal Renal Artery Angioplasty and Stent Placement in a Patient With a Solitary Kidney

Endovascular infections after percutaneous transluminal renal angioplasty with stenting (PTRAS) are rarely reported. Because strict longitudinal follow-up of patients undergoing PTRAS is lacking, the true incidence of such complications remains obscure. We report the first case of a patient with an infected renal artery pseudoaneurysm and de novo mycotic aortic aneurysm after PTRAS. This case serves to illustrate several important points, including (1) the retrieval of renal function in patients with renal artery occlusion, (2) the pathogenesis of infection after PTRAS, (3) the diagnosis and management of endovascular infection after percutaneous vascular intervention, and (4) recommendations for periprocedural antibiotic prophylaxis during PTRAS.
Rectification at n-n GaAs:(Ga,Al)As heterojunctions

n-n Ga0.7Al0.3As: GaAs heterojunction structures have been grown by l.p.e., with 1 × 1015 cm-3 net carriers in the ternary. N/W profiling across the heterojunction shows an accumulation region on the GaAs side and a depletion region on the (Ga, Al)As side. I/V characteristics at room temperature show significant rectification.
The Future of Environmental Ethics

Environmental ethics has a future as long as there are moral agents on Earth with values at stake in their environment. Somewhat ironically, just when humans, with their increasing industry and development, seemed further and further from nature, having more power to manage it, just when humans were more and more rebuilding their environments with their super technologies, the natural world emerged as a focus of ethical concern. Environmental alarms started with prophets such as Aldo Leopold, Rachel Carson, John Muir, and David Brower, and have, over recent decades, become daily news.
A simulation of the Schwinger model in the overlap formalism

Abstract In the continuum, the single flavor massless Schwinger model has an exact global axial U (1) symmetry in the sector of perturbative gauge fields. This symmetry is explicitly broken by gauge fields with nonzero topological charge inducing a nonzero expectation value for the bilinear ψ ψ. We show that a lattice formulation of this model, using the overlap formalism to treat the massless fermions, explicitly exhibits this phenomenon. A Monte Carlo simulation of the complete system yields the correct value of the fermion condensate and shows unambiguously that it originates from the sector of topological charge equal to unity.
The unexpected and differential effect of cyclosporin A on CD56Bright and CD56Dim NK cell expansion, phenotype, function and development from progenitor cells

Following allogeneic hematopoietic cell transplantation, NK cells play important roles in hematopoietic cell engraftment, anti-viral responses, graft vs. host disease (GVHD) and graft vs. leukemia (GVL) reactions. Calcineurin inhibitors, such as cyclosporine A (CsA), are frequently administered to prevent or treat GVHD. It is generally considered that these immune suppressive agents inhibit GVL reactions. To date, little is known about the impact of these immune suppressants on NK cell function. To investigate this, NK cells were isolated from normal donors by negative selection and cultured with IL-2 (100 U/ml), IL-15 (10 ng/ml) and either physiological levels of CsA (1μg/ml) or vehicle control. Under these conditions, we consistently found that CsA treated cultures showed a reduction in NK cell expansion at one week (4.88 vs. 1.87 fold expansion, n=10). The phenotype of CsA treated NK cells was markedly different than controls. More specifically, after 7–10 days of culture with CsA there were significantly more CD56 bright CD16 − cells and significantly less CD56 dim CD16 + cells compared to controls (p dim CD16 + and CD56 bright CD16 − cell division. There was no difference in the proliferation of CD56 bright CD16 − cells between the CsA and control treated cultures. In contrast, the CsA treated CD56 dim CD16 + cells had fewer cell divisions, demonstrating that CsA selectively inhibits CD56 dim CD16 + cell proliferation. These results were confirmed by determining the fold expansion of freshly isolated, FACS sorted CD56 dim CD16 + and CD56 bright CD16 − populations cultured with CsA or vehicle control. To investigate the cytotoxicity of CsA treated NK cells, we performed killing assays using K562 and Raji cells as targets. Surprisingly, we consistently found higher cytotoxicity in CsA treated NK cells compared to controls (K562, p + Lin − CD38 − ) using an in vitro differentiation system. Briefly, progenitor cells were cultured on a murine feeder cell line (AFT-024) for 42 days in the presence of IL-3, IL-7, IL-15, SCF and FLT3L +/− CsA. We found that CsA treated cultures had less KIR expressing cells compared to controls. Collectively these results show that physiological levels of CsA inhibit CD56 dim CD16 + cell growth and result in a population of NK cells that have less KIR receptor expression, higher cytotoxicity and more cytokine secretion. These findings may have important implications for both GVHD and GVL following hematopoietic cell transplantation.
New optimality principles for economic efficiency and equilibrium

This paper develops several optimization principles relating the fundamental concepts of Pareto efficiency and competitive equilibria. The beginning point for this development is the introduction of a new function describing individual preferences, closely related to willingness-to-pay, termed the benefit function. An important property of the benefit function is that it can be summed across individuals to obtain a meaningful measure of total benefit relative to a given set of utility levels; and the optimization principles presented in the paper are based on maximization of this total benefit. Specifically, it is shown that, under appropriate technical assumptions, a Pareto-efficient allocationX maximizes the total benefit relative to the utility levels it yields. Conversely, if an allocationX yields zero benefit and maximizes the total benefit function, then that allocation is Pareto efficient. The Lagrange multipliersp of the benefit maximization problem serve as prices; and the (X,p) pair satisfies a generalized saddle-point property termed a Lagrange equilibrium. This in turn is equivalent, under appropriate assumptions, to a competitive equilibrium. There are natural duals to all of the results stated above. The dual optimization principle is based on a surplus function which is a function of prices. The surplus is the total income generated at pricesp, minus the total income required to obtain given utility levels. The dual optimization principle states that prices that are dual (or indirect) Pareto efficient minimize total surplus and render it zero. Conversely, a set of prices that minimizes total surplus and renders it zero is a dual Pareto efficient set of prices. The results of the paper can be viewed as augmenting the first and second theorems of welfare economics (and their duals) to provide a family of results that relate the important economic concepts of Pareto efficiency, equilibrium, dual (or indirect) Pareto efficiency, total benefit, Lagrange equilibrium, and total surplus.
No Such Thing as a Free Safe Lunch: The Cost of Food Safety Regulation in the Meat Industry

This study develops theoretical and econometric cost function models for the meat industry to test the hypothesis of safety exogeneity, i.e., that product safety does not affect productive efficiency. Using plant-level data from the Census of Manufactures, this hypothesis is rejected. Estimates of the impacts of food safety regulation on variable cost of production in the beef, pork, and poultry industries show that the efficiency costs of food safety regulations could plausibly exceed benefits estimated by the U.S. Department of Agriculture. Costs of regulation per pound of meat are found to be size neutral for all but the smallest plants. Copyright 2000, Oxford University Press.
Location and orientation of adsorbed molecules in zeolites from solid-state REAPDOR NMR

The use of rotational echo adiabatic passage double resonance (REAPDOR) solid-state nuclear magnetic resonance (NMR) to determine the site location of an adsorbed polar molecule in a zeolite cage is presented. Nitrogen-15 labeled ammonia is used as a probe molecule to characterize the initial adsorption site in 3A zeolite molecular sieves. The relative position of the ammonia adsorption site in the cage is determined by measuring the internuclear distance between the N on ammonia and both a Na cation site and an Al framework environment using 15N/23Na and 15N/27Al REAPDOR NMR experiments, respectively. The measured internuclear distances are similar to a specific ammonia adsorption site for the zeolite 4A ammonia sorption complex located using X-ray diffraction. Additional details regarding the ammonia hydrogen-bonding environment can be extracted from 1H/23Na and 1H/27Al REAPDOR NMR measurements.
Generalized orbifold Euler characteristics of symmetric orbifolds and covering spaces

Let G be a finite group and let M be a G-manifold. We introduce the concept of generalized orbifold invariants of M/G associated to an arbitrary group Γ, an arbitrary Γ-set, and an arbitrary covering space of a connected manifold Σ whose fundamental group is Γ. Our orbifold invariants have a natural and simple geometric origin in the context of locally constant G-equivariant maps from G-principal bundles over covering spaces of Σ to the G-manifold M. We calculate generating functions of orbifold Euler characteristic of symmetric products of orbifolds associated to arbitrary surface groups (orientable or non-orientable, compact or non-compact), in both an exponential form and in an infinite product form. Geometrically, each factor of this infinite product corresponds to an isomorphism class of a connected covering space of a manifold Σ. The essential ingredient for the calculation is a structure theorem of the centralizer of homomorphisms into wreath products described in terms of automorphism groups of Γ-equivariant G-principal bundles over finite r-sets. As corollaries, we obtain many identities in combinatorial group theory. As a byproduct, we prove a simple formula which calculates the number of conjugacy classes of subgroups of given index in any group. Our investigation is motivated by orbifold conformal field theory.
Fast Approximation Algorithms for Cut-Based Problems in Undirected Graphs

We present a general method of designing fast approximation algorithms for cut-based minimization problems in undirected graphs. In particular, we develop a technique that given any such problem that can be approximated quickly on trees, allows approximating it almost as quickly on general graphs while only losing a poly-logarithmic factor in the approximation guarantee. To illustrate the applicability of our paradigm, we focus our attention on the undirected sparsest cut problem with general demands and the balanced separator problem. By a simple use of our framework, we obtain poly-logarithmic approximation algorithms for these problems that run in time close to linear. The main tool behind our result is an efficient procedure that decomposes general graphs into simpler ones while approximately preserving the cut-flow structure. This decomposition is inspired by the cut-based graph decomposition of R\"acke that was developed in the context of oblivious routing schemes, as well as, by the construction of the ultrasparsifiers due to Spiel man and Teng that was employed to preconditioning symmetric diagonally-dominant matrices.
Interfirm Alliances in the Small Business: The Role of Social Networks

In light of the increasing importance of strategic alliances in shaping competition, this study explored whether the social network of small firm executives can be leveraged to facilitate the establishment of interfirm alliances. Analyses are based on a mail survey of 149 small manufacturing firms in the northeast United States. Results indicate that the social networks of senior executives account for 11–22 percent of the variance in the degree to which firms engage in alliances, depending on the type of alliance. Results also show that the number of interfirm alliances is positively related to several networking properties (propensity to network, strength of ties, and network prestige). Findings are discussed in the context of network theory, social embeddedness, and the overall implications for management researchers and practitioners.
Subsonic aerodynamics of rectangular parallelepiped shapes of fineness ratio of one-half

Results from static and dynamic stability wind-tunnel tests at subsonic speeds are presented for rectangular cylinders having a fineness ratio of about one-half. Aerodynamic data were obtained over ranges of angles of attack and roll sufficient to construct aerodynamic inputs to a six-degree-of-freedom re-entry simulation for the full rotational motion experienced by a free-falling body. The effects of Reynolds number, edge roundness, angle of attack, and roll angle were investigated. Free-fall tests of the model are also described. The aerodynamic characteristics were found to be highly nonlinear with the various geometric and flow variables investigated, especially at attitudes near broad face and narrow side to the wind.
Economic scales for first-generation biomass-gasifier/gas turbine combined cycles fueled from energy plantations

This paper assesses the scales at which commercial, first-generation biomass integrated-gasifier/gas turbine combined cycle (BIG/GTCC) technology is likely to be most economic when fueled by plantation-derived biomass. First-generation BIG/GTCC systems are likely to be commercially offered by vendors beginning around 2000 and will be based on either pressurized or atmospheric-pressure gasification. Both plant configurations are considered here, with estimates of capital and operating costs drawn from published and other sources. Prospective costs of a farm-grown energy crop (switchgrass) delivered to a power plant are developed with the aid of a geographic information system (GIS) for agricultural regions in the North Central and Southeast US in the year 2000 and 2020. A simplified approach is applied to estimate the cost of delivering chipped eucalyptus from an existing plantation in Northeast Brazil. The optimum capacity (MW{sub opt}), defined as that which yields the minimum calculated cost of electricity (COE{sub m}), varies by geographic region due to differences in delivered biomass costs. With pressurized BIG/GTCC plants, MW{sup opt} is in the range of 230--320 MW{sub e} for the sites considered, assuming most of the land around the power plant is farmed for energy crop production. For atmospheric-pressure BIG/GTCC plants, MW{sub opt} ranges frommore » 110 to 142 MW{sub e}. When a lower fraction of the land around a plant is used for energy farming, values for MW{sub opt} are smaller than these. In all cases, the cost of electricity is relatively insensitive to plant capacity over a wide range around MW{sub opt}.« less
Immunogenetics of killer cell immunoglobulin-like receptors

The killer cell immunoglobulin receptor locus (KIR) on human chromosome 19 encodes activating and inhibitory receptors that are expressed principally by NK cells but also by subpopulations of T cells. For some of the KIR the ligands are known to be MHC class I molecules, for others ligands are elusive. In humans the KIR locus is highly diverse. KIR haplotypes differ in gene content and the individual genes exhibit allelic polymorphism; these two components work together to diversify haplotypes, which in pairwise combination diversify human KIR genotypes. The divergence of KIR between different human populations, as well as between closely related hominoid species, seem likely to be the products of balancing and directional selection upon the functions of KIR-expressing lymphocytes. Consistent with this model are the results of several studies associating KIR differences with disease susceptibility, immune responsiveness and events following allogeneic transplantation.