cssi/SciSciGPT-SciSciNet huggingface dataset:
Identification of Protein-Bound Dinitrosyl Iron Complexes by Nuclear Resonance Vibrational Spectroscopy

We have applied (57)Fe nuclear resonance vibrational spectroscopy (NRVS) to identify protein-bound dinitrosyl iron complexes. Intense NRVS peaks due to vibrations of the N-Fe-N unit can be observed between 500 and 700 cm(-1) and are diagnostic indicators of the type of iron dinitrosyl species present. NRVS spectra for four iron dinitrosyl model compounds are presented and used as benchmarks for the identification of species formed in the reaction of Pyrococcus furiosus ferredoxin D14C with nitric oxide.
Turbulent diffusion of magnetic fields in weakly ionized gas

The diffusion of unidirectional magnetic fields by two-dimensional turbulent flows in a weakly ionized gas is studied. The fields here are orthogonal to the plane of fluid motion. This simple model arises in the context of the decay of the mean magnetic flux-to-mass ratio in the interstellar medium. When ions are strongly coupled to neutrals, the transport of a large-scale magnetic field is driven by both turbulent mixing and nonlinear, ambipolar drift. Using a standard homogeneous and Gaussian statistical model for turbulence, we show rigorously that a large-scale magnetic field can decay on turbulent mixing timescales when the field and neutral flow are strongly coupled. There is no enhancement of the decay rate by ambipolar diffusion. These results extend the Zeldovich theorem to encompass the regime of two-dimensional flows and orthogonal magnetic fields, recently considered by Zweibel. The limitation of the strong coupling approximation and its implications are discussed.
The impact of the taxpayer relief act of 1997 on housing turnover in the U.S. single-family residential market

The Taxpayer Relief Act of 1997 (TRA97) replaced a one-time, post-age-55 capital gain exclusion with a larger gain exclusion amount that could be protected every two years without requiring that the taxpayer trades up in housing. This action had the potential to impact housing transactions for every existing homeowner, regardless of age, as well as future purchasers of housing. We analyze household-level data to determine if the repeated ability to exclude periodic recognized capital gains on housing from taxation shortened housing tenure significantly after TRA97 became effective. We next consider whether the decline was heterogeneous across age groups, across trading up and trading down and across geography. Given that the impact of TRA97 appears at first glance to be most profound for taxpayers close to 55 years of age, a somewhat surprising result of our research is that significant decreases in tenure are pervasive, appearing in all age ranges and in samples of homeowners who trade up and who trade down. Finally, we provide additional evidence at the aggregate level that TRA97 led to measurable changes in the price elasticity of housing turnover in the four geographic regions defined by the U.S. Census Bureau (Northeast, Midwest, South and West) and in states that are home to large metropolitan housing markets.
On the relationship between Hamiltonian chaos and classical gravity

Abstract It is known that Hamiltonian equations of motion for low-dimensional chaotic systems are typically formulated using fractional derivatives. The evolution of such systems is governed by the fractional diffusion equation, which describes self-similar and non-Gaussian processes with strong intermittencies. We confirm, in this context, that the dynamics of a Brownian particle driven by space-time dependent fluctuations evolves towards Hamiltonian chaos and fractional diffusion. The corresponding motion of the particle has a time-dependent and nowhere vanishing acceleration. Invoking the equivalence principle of general relativity leads to the conclusion that fractional diffusion is locally equivalent to a transient gravitational field. It is shown that gravity becomes renormalizable as Newton’s constant converges towards a dimensionless quantity.
Do Professors’ Opinions Affect Students?

This paper estimates the effect that professors’ opinions have on changes in student opinions during introductory economics classes. The paper shows that students are more likely to change their opinion during the course of the semester if their initial response differs from that of the professor, and this result emerges even after controlling for students’ tendency to move toward the consensus opinion held by all the economics professors. Students are also more likely to change their opinions if they differ from the opinions of their classmates, and the estimates show that in the aggregate, classmate opinions matter more than professor opinions do. The data also show that students choose which section to attend at least partly based on how closely their pre-class opinions match those of the professor. These results have important implications for both heterodox and orthodox economists.
Information theory lateral density distribution for Earth inferred from global gravity field

Information theory inference, better known as the maximum entropy method, is used to infer the lateral density distribution inside the earth. The approach assumes that the earth consists of indistinguishable Maxwell-Boltzmann particles populating infinitesimal volume elements and follows the standard methods of statistical mechanics (maximizing the entropy function). The GEM 10B spherical harmonic gravity field coefficients, complete to degree and order 36, are used as constraints on the lateral density distribution. The spherically symmetric part of the density distribution is assumed to be known. The lateral density variation is assumed to be small in comparison with the spherically symmetric part. The resulting information theory density distribution for the cases of no crust removed, 30 km of compensated crust removed, and 30 km of uncompensated crust removed all give broad density anomalies extending deep into the mantle, but with the density contrasts being the greatest toward the surface (typically ±0.004 g cm−3 in the first two cases and ±0.04 g cm−3 in the third). None of the density distributions resemble classical organized convection cells. The information theory approach may have use in choosing standard earth models, but the inclusion of seismic data into the approach appears difficult.
Mechanistic Model for Tapping Process With Emphasis on Process Faults and Hole Geometry

A mechanistic approach for modeling the tapping process is presented. A methodology for computing chip load is developed for an arbitrary tap geometry. The mechanics of cutting for tapping is analyzed, considering it as an oblique cutting phenomenon. The effects of tap geometry (tap diameter, thread pitch, number of flutes, flute helix angle, tooth rake angle, and thread type), workpiece geometry (hole diameter and hole depth), process parameters (spindle speed and tap penetration depth), and process faults (tap runout, axis misalignment, and drilled hole geometry) are incorporated in the model. The model is calibrated using drilling experiments and is validated by comparing experimental tapping results for aluminum 319, aluminum 356, and gray cast iron. In most cases, the tapping forces were predicted within 10 percent of the experimental values.
Tidal signatures in the faintest milky way satellites: The detailed properties of Leo V, Pisces II, and Canes Venatici II

We present deep wide-field photometry of three recently discovered faint Milky Way (MW) satellites: Leo V, Pisces II, and Canes Venatici II. Our main goals are to study the structure and star formation history of these dwarfs; we also search for signs of tidal disturbance. The three satellites have similar half-light radii ({approx}60-90 pc) but a wide range of ellipticities. Both Leo V and CVn II show hints of stream-like overdensities at large radii. An analysis of the satellite color-magnitude diagrams shows that all three objects are old (>10 Gyr) and metal-poor ([Fe/H] {approx} -2), though neither the models nor the data have sufficient precision to assess when the satellites formed with respect to cosmic reionization. The lack of an observed younger stellar population ({approx} 150 kpc. We present a new compilation of structural data for all MW satellite galaxies and use it to compare the properties of classical dwarfs to the ultra-faints. The ellipticity distribution of the two groups is consistent at the {approx}2{sigma} level. However, the faintest satellites tend to be more aligned toward the Galactic Center, and those satellites with the highest ellipticitymore » ({approx}> 0.4) have orientations ({Delta}{theta}{sub GC}) in the range 20 Degree-Sign {approx}< {Delta}{theta}{sub GC} {approx}< 40 Degree-Sign . This latter observation is in rough agreement with predictions from simulations of dwarf galaxies that have lost a significant fraction of their dark matter halos and are being tidally stripped.« less
Chemical approaches for detection and destruction of nerve agents

Since the introduction of organophosphorus (OP) compounds as nerve agents and pesticides, methods of dealing with their toxicity to humans have been intensely researched. There are studies on sensing, pretreatments, prophylactics, antidotes and therapies. There is some overlap in all of these endeavors because they have to deal with the reactivity of the phosphorus atom in various contexts. The contexts range from large spaces, the thinly spread vapors in the air, to very small spaces in the active sites of enzymes – acetylcholinesterase (AChE) or butyrylcholinesterase (BuChE) – that have reacted with the OP agent.
Dark materials in Valles Marineris: Indications of the style of volcanism and magmatism on Mars

Computer mapping of spectral reflectance in Viking Orbiter I multispectral images is combined with photogeological interpretation and used to examine the geological significance of the dark materials in Valles Marineris, a canyon system that provides a unique view of the interior of the Martian crust. Special consideration is given to the relation of the dark materials to the past episodes of tectonism, volcanic activity, and igneous intrusion. Spectral mapping suggests that the dark floor-covering materials in the lower canyon are derived from a thick deposit composed of mafic glass, possibly an ancient Martian analogue of the lunar terra mantling deposits. Application of computer mapping techniques to probable young volcanic materials in the central troughs yields an inferred distribution of volcanic activity consistent with the interpretation of extrusion along faults near the margins of the canyon floors. The results support the hypothesis that Valles Marineris originated through tectonic extension.
SOLIDS CONCENTRATION EFFECTS IN BENTONITE DRILLING FLUIDS

A series of studies of the apparent electrokinetic potential and other characteristics of aqueous bentonite systems as they are affected by bentonite concentration is presented. A new concentration parameter, which logically arises from a previously presented filtration theory (Oakes, 1958), is demonstrated to describe adequately the effects of solids concentration. The concentration parameter is analytically derived and is shown to make suitable allowance for the adsorbed phase on the bentonite patricles.
Electrophilic and nucleophilic approaches to the synthesis of 3-fluorodiazepam

Abstract Electrophilic fluorination of diazepam with elemental fluorine or gas phase acetyl hypofluorite gave 3-fluorodiazepam in 20–60% yields. Nucleophilic displacement of chlorine in 3-chlorodiazepam by fluoride ion also gave 3-fluorodiazepam in modest yields (maximum: 21%). Both of these methods were used for the synthesis of 18 F-labelled 3-fluorodiazepam.
Multidisciplinary analysis and optimization of discrete problems using response surface methods

The objective of this paper is to present a new algorithm to efficiently optimize multidisciplinary, coupled nonhierarchic systems with discrete variables. The algorithm decomposes the system into contributing disciplines, and uses designed experiments within the disciplines to build local response surface approximations to the discipline analysis. First and second order Global Sensitivity Equations are formulated and approximated by experimental data to build approximations to the global design space. The global approximation is optimized using branch and bound or simulated annealing. Convergence is rapid for systems with near quadratic behavior. The algorithm is demonstrated on a unique multidisciplinary learning tool, the Design and Manufacturing Learning Environment. This environment provides multimedia simulation for product life cycle disciplines, including design, manufacturing, marketing, and sales.
Missile sizing for ascent-phase intercept

A computer code has been developed to determine the size of a ground-launched, multistage missile which can intercept a theater ballistic missile before it leaves the atmosphere. Typical final conditions for the inteceptor are 450 km range, 60 km altitude, and 80 sec flight time. Given the payload mass (35 kg), which includes a kinetic kill vehicle, and achievable values for the stage mass fractions (0.85), the stage specific impulses (290 sec), and the vehicle density (60 lb/ft{sup 3}), the launch mass is minimized with respect to the stage payload mass ratios, the stage burn times, and the missile angle of attack history subject to limits on the angle of attack (10 deg), the dynamic pressure (60,000 psf), and the maneuver load (200,000 psf deg). For a conical body, the minimum launch mass is approximately 1900 kg. The missile has three stages, and the payload coasts for 57 sec. A trade study has been performed by varying the flight time, the range, and the dynamic pressure Emits. With the results of a sizing study for a 70 lb payload and q{sub max} = 35,000 psf, a more detailed design has been carried out to determine heat shield mass, tabular aerodynamics,more » and altitude dependent thrust. The resulting missile has approximately 100 km less range than the sizing program predicted primarily because of the additional mass required for heat protection. On the other hand, launching the same missile from an aircraft increases its range by approximately 100 km. Sizing the interceptor for air launch with the same final conditions as the ground-launched missile reduces its launch mass to approximately 1000 kg.« less
A comparative economic analysis of straight-through and recirculation solar hot water systems

Abstract A thermal and life cycle analysis was conducted to compare two types of solar service hot water systems: 1. (1) the straight-through system with the water driven by the pressure of the mains through a heat exchanger in which it is heated by the warmer water in the solar-thermal storage tank, whenever demand for service hot water is created, and 2. (2) the recirculation system in which a temperature-difference-controlled recirculation loop is used between the solar-thermal storage tank and the auxiliary (or backup) service hot water tank. The latter configuration which needs to have these additional components (controller, pump, and piping) and may thus also be less reliable, is more frequently used when the solar system is to supply both space heat and service hot water, because it is generally though to provide a larger fraction of the hot water from the solar source. A computer program, combining TRNSYS with a comprehensive present-value life-cycle model and an optimization link was prepared and run for a representative year in Philadelphia to determine the thermal storage, heat exchanger, and controller-setting combination which produces the minimal present-value life-cycle costs. To provide more generality to the results, these calculations were repeated for a wide range of temperature levels and transient patterns of the solar-collector-heated water in storage and of the service hot water demand patterns, quantities, and temperatures. Apart from some uncommon cases, it was found that the straight-through solar heating system is better than the recirculation one with respect to all comparison criteria: present-value life-cycle cost, auxiliary energy consumption, and reliability.
An Experimental Study of Travelling-Bubble Cavitation Noise

Abstract : In this investigation, high-frequency travelling-bubble cavitation noise generated on a Schiebe headform is analyzed with regard to noise theories which are based on the collapse of a single bubble. After normalizing the noise level by an event rate, -sigma C(p(min)) appears to provide a reasonable scaling factor for the noise level radiated per collapse, where sigma is the cavitation number and C(p(min)) is the minimum pressure coefficient on the headform. At frequencies above 10 kHz and free-stream flow velocities between 9.1 and 12.2 mps (30 and 40 fps), the noise level per collapse varied as roughly 1/sigma to the 8.4 power, and was constant with the flow velocity for constant -sigma/C(p(min)). The energy density spectra were flat from 10 to 100 kHz regardless of the cavitation number or free-stream velocity. (Author)
Radiative Metallic Thermal Protection Systems: A Status Report

During the early stages of the space shuttle program there were a number of technological uncertainties concerning the applicability of metallic thermal protection systems (TPS) to the multimission environment of the shuttle. To resolve the uncertainties and to advance the state-of-the-art, the NASA-Langley Research Center initiated a broad-based technology program to develop metallic TPS over the temperature range from 810 K to 1590 K. Wind tunnel tests conducted to assess the influence of surface/stream interaction of wavy surfaces on the design of metallic TPS indicate small increases in heat flux and surface drag for flow angles less than 20 deg. Analytical and experimental investigations, recently completed, have significantly improved prediction methods for cyclic creep behavior of TPS components repeatedly exposed to complex mission cycles. Thermal/structural concept optimization studies to minimize mass while maintaining structural integrity have led to advanced designs with unit masses which are competitive with those for shuttle RSI. In addition, the durability and reusability of metallic TPS have been repeatedly demonstrated in tests of full-scale systems. The current state-of-the-art strongly suggests that radiative metallic TPS have come of age.
[Hg5O2(OH)4][(UO2)2(AsO4)2]: A complex mercury(II) uranyl arsenate

Abstract Under mild hydrothermal conditions UO2(NO3)2·6H2O, Hg2(NO3)2·2H2O, and Na2HAsO4·7H2O react to form [Hg5O2(OH)4][(UO2)2(AsO4)2] (HgUAs-1). Single crystal X-ray diffraction experiments reveal that HgUAs-1 possesses a pseudo-layered structure consisting of two types of layers: ∞ 2 [ Hg 5 O 2 ( OH ) 4 ] 2 + and ∞ 2 [ ( UO 2 ) 2 ( AsO 4 ) 2 ] 2 - . The ∞ 2 [ Hg 5 O 2 ( OH ) 4 ] 2 + layers are complex, and contain three crystallographically unique Hg centers. The coordination environments and bond–valence sum calculations indicate that the Hg centers are divalent. The ∞ 2 [ ( UO 2 ) 2 ( AsO 4 ) 2 ] 2 - layers belong to the Johannite topological family. The ∞ 2 [ Hg 5 O 2 ( OH ) 4 ] 2 + and ∞ 2 [ ( UO 2 ) 2 ( AsO 4 ) 2 ] 2 - layers are linked to each other through μ2-O bridges that include Hg⋯O=U=O interactions.
The elusive 8-fluoroadenosine

Abstract The synthesis of 8-fluoroadenosine has been accomplished for the first time. The kinetics of deamination of 8-fluoroadenosine with the enzyme adenosine deaminase has also been measured.
Novel method for chemical vapor deposition and atomic layer epitaxy using radical chemistry

Abstract A novel method for chemical vapor deposition and atomic layer epitaxy using radical precursors under medium vacuum conditions is being developed. Fluorine atoms are generated by thermal dissociation in a hot tube and abstract hydrogen atoms from precursor molecules injected immediately downstream of the source, generating radicals with complete chemical specificity. The radical precursors are then transported to the growing substrate surface under nearly collision-free conditions. To date we have grown diamond films from CCl 3 radicals together with atomic hydrogen, generated by injecting CHCl 3 and H 2 into the fluorine atom stream at reactor pressures between 10 −3 and 10 −2 Torr. This approach should be ideal for low-temperature growth and atomic layer epitaxy: growth rates remain relatively high because activation energies for radical reactions are typically small and because the cycle times for atomic layer epitaxy can be reduced to the millisecond range by fast gas-stream switching, and contamination and segregation are minimized by keeping the surface “capped” by chemisorbed intermediates and working under ultraclean conditions.
Outcome for children with supratentorial primitive neuroectodermal tumors treated with surgery, radiation, and chemotherapy.

BACKGROUND The outcome of a child with a primitive neuroectodermal tumors arising supratentorially (SPNET) is not well characterized and may differ from the outcome of a patient with a histologically similar cerebellar tumor (medulloblastoma [MB]). Recently, 5-year progression free survival rates as high as 80% have been reported for children with MB treated with craniospinal radiation (CRT) and chemotherapy including cisplatin, lomustine (CCNU), and vincristine (VCR). METHODS The authors reviewed the outcome of 22 consecutive patients age 3 years and older (mean age, 10 years; range, 3-18 years) with SPNET who were treated at the study institutions between 1981 and 1996. Tumor location included was 13 pineal, 6 cortical, and 3 thalamic or suprasellar. Five patients had disease dissemination at diagnosis. All patients underwent surgery and staging, followed by CRT and chemotherapy with cisplatin, CCNU, and VCR. RESULTS Of the 22 patients, 13 had developed disease progression and 10 had died at the time of last follow-up. Overall progression free survival (PFS) was 47% ± 11% at 3 years and 37% ± 11% at 5 years. There was a significant difference in PFS between patients with localized disease versus those with disseminated disease (P = 0.04). There was no statistical association between tumor location and survival. Although not significant (P = 0.21), there was a trend toward better survival of those patients with complete or near-complete resection compared with those with partial resection or biopsy. CONCLUSIONS The results of the current study demonstrate that the outcome for children with SPNET treated with radiation and chemotherapy appears worse than for children with MB treated with identical therapy. This suggests that there may be biologic differences between supratentorial and infratentorial primitive neuroectodermal tumors, thus requiring refinements in treatment. Cancer 2000;88:2189–93. © 2000 American Cancer Society.
SILICA GEL SUPPORTED JONES REAGENT (SJR): A SIMPLE AND EFFICIENT REAGENT FOR OXIDATION OF BENZYL ALCOHOLS TO BENZALDEHYDES

Jones reagent supported on silica gel (SJR) has been used for oxidation of benzyl alcohols to the corresponding benzaldehydes in high yields utilizing organic solvent. This newly developed reagent is easy to prepare and use. SJR is also safer than the traditional Jones reagent.
Bounds for the first eigenvalue of the horizontal Laplacian in positively curved sub-Riemannian manifolds

We establish lower bounds for the first non-zero eigenvalue for the natural geometric sub-elliptic Laplacian operator defined on sub-Riemannian manifolds of step 2 that satisfy a positive curvature condition. The methods are very general and can be applied even when the sub-Riemannian geometry has considerable torsion.
CHALLENGES POSED TO OPERATIONS MANAGEMENT BY THE “NEW ECONOMY”

A growing number of sophisticated observers are coming to believe that the forces driving the so-called New Economy are fundamentally reshaping world industry. Moreover, the combination of fast growth and the excitement associated with leading edge technologies has made New Economy companies magnets for management talent—and particularly for the ambitious young people who attend our management programs. Are we providing these potential managers with a good foundation for managing operations in such companies? Are the principles that we traditionally have taught in operations management (om) courses sufficiently robust that they can still be applied to New Economy operations? In this paper we argue that, although some of our familiar concepts and techniques continue to be applicable to information-intensive operations, many are not. We sketch out a way to think conceptually about the important differences between the Old and the New Economies, and their implications for operations management teaching and research.
Reassessing the empirical validity of the human-capital augmented neoclassical growth model

We reassess Mankiw, Romer and Weil’s [MRW] version of the Solow model using, as did MRW, cross-sectional data to estimate the steady-state equation governing income per capita levels. The model fails in two critical areas. First, plausible factor shares obtained by MRW are not robust to the substitution of two measures of human capital that are more precise than the secondary school enrollment rates used by MRW. Second, the null hypothesis of an exogenous and identical level of technology in all countries is rejected. We also explain why the Solow model performed well despite the above shortcomings.
Graph-theoretic construction of low-density parity-check codes

This paper presents a novel graph-theoretic method for constructing low-density parity-check (LDPC) codes from connected graphs-without the requirement of large girth. The method is based on finding a set of paths in a connected graph, which satisfies the constraint that any two paths in the set are either disjoint or cross each other at one and only one vertex. Two trellis-based algorithms for finding these paths are devised. Good LDPC codes of practical lengths are constructed and they perform well with iterative decoding.
PEG Branched Polymer for Functionalization of Nanomaterials with Ultralong Blood Circulation

Nanomaterials have been actively pursued for biological and medical applications in recent years. Here, we report the synthesis of several new poly(ethylene glycol) grafted branched polymers for functionalization of various nanomaterials including carbon nanotubes, gold nanoparticles (NPs), and gold nanorods (NRs), affording high aqueous solubility and stability for these materials. We synthesize different surfactant polymers based upon poly(γ-glutamic acid) (γPGA) and poly(maleic anhydride-alt-1-octadecene) (PMHC18). We use the abundant free carboxylic acid groups of γPGA for attaching lipophilic species such as pyrene or phospholipid, which bind to nanomaterials via robust physisorption. Additionally, the remaining carboxylic acids on γPGA or the amine-reactive anhydrides of PMHC18 are then PEGylated, providing extended hydrophilic groups, affording polymeric amphiphiles. We show that single-walled carbon nanotubes (SWNTs), Au NPs, and NRs functionalized by the polymers exhibit high stability in aqueous...
Asset bubbles in an overlapping generations model with endogenous labor supply

This paper examines the effects of asset bubbles in an overlapping generations model with endogenous labor supply. We show analytically that asset bubbles can lead to an expansion in steady-state capital, investment, employment and output under certain conditions.
The Effect of Galactic Properties on the Escape Fraction of Ionizing Photons

The escape fraction, f esc, of ionizing photons from early galaxies is a crucial parameter for determining whether the observed galaxies at z ≥ 6 are able to reionize the high-redshift intergalactic medium. Previous attempts to measure f esc have found a wide range of values, varying from less than 0.01 to nearly 1. Rather than finding a single value of f esc, we clarify through modeling how internal properties of galaxies affect f esc through the density and distribution of neutral hydrogen within the galaxy, along with the rate of ionizing photons' production. We find that the escape fraction depends sensitively on the covering factor of clumps, along with the density of the clumped and interclump medium. One must therefore be cautious when dealing with an inhomogeneous medium. Fewer high-density clumps lead to a greater escape fraction than more numerous low-density clumps. When more ionizing photons are produced in a starburst, f esc increases, as photons escape more readily from the gas layers. Large variations in the predicted escape fraction, caused by differences in the hydrogen distribution, may explain the large observed differences in f esc among galaxies. Values of f esc must also be consistent with the reionization history. High-mass galaxies alone are unable to reionize the universe, because f esc >1 would be required. Small galaxies are needed to achieve reionization, with greater mean escape fraction in the past.
Survey of computer programs for heat transfer analysis

An overview is given of the current capabilities of thirty-three computer programs that are used to solve heat transfer problems. The programs considered range from large general-purpose codes with broad spectrum of capabilities, large user community, and comprehensive user support (e.g., ABAQUS, ANSYS, EAL, MARC, MITAS II, MSC/NASTRAN, and SAMCEF) to the small, special-purpose codes with limited user community such as ANDES, NTEMP, TAC2D, TAC3D, TEPSA and TRUMP. The majority of the programs use either finite elements or finite differences for the spatial discretization. The capabilities of the programs are listed in tabular form followed by a summary of the major features of each program. The information presented herein is based on a questionnaire sent to the developers of each program. This information is preceded by a brief background material needed for effective evaluation and use of computer programs for heat transfer analysis. The present survey is useful in the initial selection of the programs which are most suitable for a particular application. The final selection of the program to be used should, however, be based on a detailed examination of the documentation and the literature about the program.
Effects of S-adenosylmethionine augmentation of serotonin-reuptake inhibitor antidepressants on cognitive symptoms of major depressive disorder

Abstract Background Major depressive disorder (MDD) is often accompanied by significant cognitive impairment, and there are limited interventions specific to this particular symptom. S-adenosyl methionine (SAMe), a naturally occurring molecule which serves as a major methyl-donor in human cellular metabolism, is required for the synthesis and maintenance of several neurotransmitters that have been implicated in the pathophysiology and treatment of cognitive dysfunction in MDD. Methods This study is a secondary analysis of a clinical trial involving the use of adjunctive SAMe for MDD. Forty-six serotonin-reuptake inhibitor (SRI) non-responders with MDD enrolled in a 6-week, double-blind, randomized trial of adjunctive oral SAMe were administered the self-rated cognitive and physical symptoms questionnaire (CPFQ), a validated measure of cognitive as well as physical symptoms of MDD, before and after treatment. Results There was a greater improvement in the ability to recall information (p = 0.04) and a trend toward statistical significance for greater improvement in word-finding (p = 0.09) for patients who received adjunctive SAMe than placebo. None of the remaining five items reached statistical significance. Conclusion These preliminary data suggest that SAMe can improve memory-related cognitive symptoms in depressed patients, and warrant replication.
Flutter Stability of a Detuned Cascade in Subsonic Compressible Flow

A mathematical model is developed to predict the unsteady aerodynamics of a detuned two-dimensional flat plate cascade in subsonic compressible flow. Aerodynamic detuning is introduced by nonuniform circumferential spacing and chordwise offset. Combined aerodynamic-structural detuning is accomplished by replacing alternate airfoils with splitter blades. A torsion mode stability analysis that considers aerodynamic and combined aerodynamic-structural detuning is developed by combining the unsteady aerodynamic model with a single degreeof-freedom structural model. The effect of these detuning techniques on flutter stability is then demonstrated by applying this model to a baseline unstable 12-bladed rotor and detuned variations of this rotor. This study demonstrates that detuning is a viable passive flutter control technique. Nomenclature A = cascade A airfoil index a — freestream speed of sound B - cascade B airfoil index CL = lift coefficient CM - moment coefficient C, = ratio of chord length of cascade B to cascade A CA = chord length of cascade A CB = chord length of cascade B ea = elastic axis location k - reduced frequency a>c/W n = airfoil index os - chordwise offset of cascade B relative to cascade A
Contention in shared memory algorithms

Most complexity measures for concurrent algorithms for asynchronous shared-memory architectures focus on process steps and memory consumption. In practice, however, performance of multiprocessor algorithms is heavily influenced by contention, the extent to which processess access the same location at the same time. Nevertheless, even though contention is one of the principal considerations affecting the performance of real algorithms on real multiprocessors, there are no formal tools for analyzing the contention of asynchronous shared-memory algorithms.This paper introduces the first formal complexity model for contention in shared-memory multiprocessors. We focus on the standard multiprocessor architecture in which n asynchronous processes communicate by applying read, write, and read-modify-write operations to a shared memory. To illustrate the utility of our model, we use it to derive two kinds of results: (1) lower bounds on contention for well-known basic problems such as agreement and mutual exclusion, and (2) trade-offs between the length of the critical path (maximal number of accesses to shared variables performed by a single process in executing the algorithm) and contention for these algorithms. Furthermore, we give the first formal contention analysis of a variety of counting networks, a class of concurrent data structures inplementing shared counters. Experiments indicate that certain counting networks outperform conventional single-variable counters at high levels of contention. Our analysis provides the first formal model explaining this phenomenon.
Grignard addition to 1-acyl salts of chiral 4-alkoxypyridines. A new enantioselective preparation of 2-alkyl-2,3-dihydro-4-pyridones

Abstract Several 2-alkyl-2,3-dihydro-4-pyridones were prepared by asymmetric addition of Grignard reagents to the 1-acyl salts of chiral 4-alkoxypyridines.
Saturn Ring Observer

Abstract Scientists studying planetary ring systems and planetary system formation have long wanted close-up (a few km) observations of Saturn's rings to answer fundamental questions about ring particle characteristics and behavior. But missions to implement these observations involve post-approach Δ V requirements greater than 10 km / s , so past designs have called upon Nuclear Electric Propulsion—an untenable position in the current programmatic climate. A unique new mission design uses carefully designed aerocapture to decrease the Δ V requirement to as little as 3.5 km / s , a difficult but not impossible feat for high-performance chemical propulsion systems. Propulsion costs dominate cost estimates for the Saturn Ring Observer mission. Driving down propulsion costs is an important facet of the strategic technology program, one that would provide cost benefits to many other missions.
The Effect of a Cosmic Ray Precursor in SN 1006

Like many young supernova remnants, SN 1006 exhibits what appear to be clumps of ejecta close to or protruding beyond the main blast wave. In this Letter, we examine three such protrusions along the east rim. They are semi-aligned with ejecta fingers behind the shock-front and exhibit emission lines from O VII and O VIII. We first interpret them in the context of an upstream medium modified by the saturated non-resonant Bell instability which enhances the growth of Rayleigh-Taylor instabilities when advected post-shock. We discuss their apparent periodicity if the spacing is determined by properties of the remnant or by a preferred size scale in the cosmic ray precursor. We also briefly discuss the alternative that these structures have an origin in the ejecta structure of the explosion itself. In this case, the young evolutionary age of SN 1006 would imply density structure within the outermost layers of the explosion with potentially important implications for deflagration and detonation in thermonuclear supernova explosion models.
Supersymmetry and the LHC inverse problem

Given experimental evidence at the LHC for physics beyond the standard model, how can we determine the nature of the underlying theory? We initiate an approach to studying the ``inverse map from the space of LHC signatures to the parameter space of theoretical models within the context of low-energy supersymmetry, using 1808 LHC observables including essentially all those suggested in the literature and a 15 dimensional parametrization of the supersymmetric standard model. We show that the inverse map of a point in signature space consists of a number of isolated islands in parameter space, indicating the existence of ``degeneracies — qualitatively different models with the same LHC signatures. The degeneracies have simple physical characterizations, largely reflecting discrete ambiguities in electroweak-ino spectrum, accompanied by small adjustments for the remaining soft parameters. The number of degeneracies falls in the range 1 < d < 100, depending on whether or not sleptons are copiously produced in cascade decays. This number is large enough to represent a clear challenge but small enough to encourage looking for new observables that can further break the degeneracies and determine at the LHC most of the SUSY physics we care about. Degeneracies occur because signatures are not independent, and our approach allows testing of any new signature for its independence. Our methods can also be applied to any other theory of physics beyond the standard model, allowing one to study how model footprints differ in signature space and to test ways of distinguishing qualitatively different possibilities for new physics at the LHC.
AESOP: a prototype for on-line user control of organizational data storage, retrieval and processing

AESOP is an experimental on-line information control system realized in the Systems Design Laboratory of The MITRE Corporation. It serves as a prototype for a class of management or command information systems capable of giving the members of the using organization as much on-line control over system performance as possible. It is a CRT display-oriented system in that the user experiences the information system primarily through his CRT displays and exercises his control through his light pencil. This control is not limited to that level of the organization responsible for programming the system, but applies upward to the highest level of executive personnel interested in obtaining direct access to the system.
Synthesis of 5-(ω-sulfhydrylalkyl)salicylaldehydes as precursors for the preparation of alkanethiol-modified metal salens

Abstract Using multistep syntheses, we obtained two alkanethiol-modified salicylaldehydes, namely 5-(2-sulfhydrylethyl)salicylaldehyde and 5-(6-sulfhydrylhexyl)salicylaldehyde. These compounds are precursors for the preparation of alkanethiol-substituted metal salens, which can potentially be used to form surface-modified gold electrodes.
Synthesis and stereochemistry of some thiazolidines related to 6-(hydroxyethyl)-penams.

Abstract L-Cysteine and D-penicillamine esters reacted with (R,R)- or (S,S)-2-t-butyl-5-dimethlylamino-methylene-6-methyl-[1,3]dioxan-4-one 3 to provide thiazolidines with high stereospecificity. The major products were potential precursors for cis-β-lactams.
Higher-Order Numerical Solutions Using Cubic Splines

A cubic spline collocation procedure was developed for the numerical solution of partial differential equations. This spline procedure is reformulated so that the accuracy of the second-derivative approximation is improved and parallels that previously obtained for lower derivative terms. The final result is a numerical procedure having overall third-order accuracy of a nonuniform mesh. Solutions using both spline procedures, as well as three-point finite difference methods, are presented for several model problems.
Formality of DG algebras (after Kaledin)

Abstract We provide proper foundations and proofs for the main results of Kaledin (2007) [Ka] . The results include a flat base change for formality and behavior of formality in flat families of A ( ∞ ) and DG algebras.
MIMO in vivo

We present the performance of MIMO for in vivo environments, using ANSYS HFSS and their complete human body model, to determine the maximum data rates that can be achieved using an IEEE 802.11n system. Due to the lossy nature of the in vivo medium, achieving high data rates with reliable performance will be a challenge, especially since the in vivo antenna performance is strongly affected by near-field coupling to the lossy medium and the signals levels will be limited by specified specific absorption rate (SAR) levels. We analyzed the bit error rate (BER) of a MIMO system with one pair of antennas placed in vivo and the second pair placed inside and outside the body at various distances from the in vivo antennas. The results were compared to SISO arrangements and showed that by using MIMO in vivo, significant performance gain can be achieved, and at least two times the data rate can be supported with SAR limited transmit power levels, making it possible to achieve target data rates in the 100 Mbps.
The impact of China’s WTO accession on trade and economic relations across the Taiwan Strait

This paper evaluates the impact of China’s World Trade Organisation (WTO) accession on trade and economic relations across the Taiwan Strait and its implications for the rest of the world by a recursive dynamic, 17-region, 25-sector computable general equilibrium (CGE) model according to actual market access commitments that China and Taiwan have made to date. The simulation results show that both China and Taiwan will substantially benefit from their WTO memberships, and their economic interdependence and their dependence within the rest of the world will further deepen. The rest of the world may also benefit because of the expansion of world trade and improvement of their international terms of trade, but some developing countries with an endowment structure similar to China, like those in South America and Southeast Asia, may experience keener competition in labour-intensive exports and lower prices for their products. JEL classification: F1, F02, C68, P52.
Computing almost shortest paths

We study the s-sources almost shortest paths (abbreviated s-ASP) problem. Given an unweighted graph G e (V,E), and a subset S ⊆ V of s nodes, the goal is to compute almost shortest paths between all the pairs of nodes S × V. We devise an algorithm with running time O(mEmnρ p s · n1 p ζ) for this problem that computes the paths Pu,w for all pairs (u,w) ∈ S × V such that the length of Pu,w is at most (1 p e) dG(u,w) p β(ζ,ρ,e), and β(ζ,ρ,e) is constant when ζ, ρ, and e are arbitrarily small constants.We also devise a distributed protocol for the s-ASP problem that computes the paths Pu,w as above, and has time and communication complexities of O(s · Diam(G) p n1 p ζ/2) (respectively, O(s · Diam(G) log3 n p n1 p ζ/2 log n)) and O(mEm nρ p s · n1 p ζ) (respectively, O(mEm nρ p s · n1 p ζ p n1 p ρ p ζ(ρ − ζ/2)/2)) in the synchronous (respectively asynchronous) setting.Our sequential algorithm, as well as the distributed protocol, is based on a novel algorithm for constructing (1 p e, β(ζ,ρ, e))-spanners of size O(n1 p ζ), developed in this article. This algorithm has running time of O(mEm nρ), which is significantly faster than the previously known algorithm given in Elkin and Peleg [2001], whose running time is O(n2 p ρ). We also develop the first distributed protocol for constructing (1 p e,β)-spanners. The communication complexity of this protocol is near optimal.
Threshold meson production and cosmic ray transport

An interesting accident of nature is that the peak of the cosmic ray spectrum, for both protons and heavier nuclei, occurs near the pion production threshold. The Boltzmann transport equation contains a term which is the cosmic ray flux multiplied by the cross section. Therefore when considering pion and kaon production from proton–proton reactions, small cross sections at low energy can be as important as larger cross sections at higher energy. This is also true for subthreshold kaon production in nuclear collisions, but not for subthreshold pion production.
On a Family of Conjectures of Joel Lewis on Alternating Permutations

We prove generalized versions of some conjectures of Joel Lewis on the number of alternating permutations avoiding certain patterns. Our main tool is the perhaps surprising observation that a classic bijection on pattern avoiding permutations often preserves the alternating property.
Synthesis and cycloaromatization kinetics of aromatic allene enynes

Abstract Aryl- and cyclopropyl-substituted allene enynes were prepared by a double olefination procedure from various aldehydes, and their cycloaromatization reactions were subjected to kinetics measurements in methanol and 1,4-cyclohexadiene solvents. The results support previous proposals of a polar diradical transition state for the cycloaromatization process.
The Topology of Cosmological Reionization

Using the largest cosmological reionization simulation to date (~24 billion particles), we use the genus curve to quantify the topology of the neutral hydrogen distribution on scales ≥1 Mpc h−1 as it evolves during cosmological reionization. We find that the reionization process proceeds primarily in an inside-out fashion, in which higher density regions become ionized earlier than lower density regions. There are four distinct topological phases: (1) pre-reionization at z 15, when the genus curve is consistent with a Gaussian density distribution; (2) preoverlap at 10 z 15, during which the number of H II bubbles increases gradually with time, until percolation of H II bubbles starts to take effect (this phase is characterized by a very flat genus curve at high volume fractions); (3) overlap at 8 z 10, when large H II bubbles rapidly merge, manifested by a precipitous drop in the amplitude of the genus curve; and (4) postoverlap at 6 z 8, when H II bubbles have mostly overlapped, and the genus curve is consistent with a diminishing number of isolated neutral islands. After the end of reionization (z 6), the genus of neutral hydrogen is consistent with Gaussian random phase, in agreement with observations.
Population-monotonic solutions to the problem of fair division when preferences are single-peaked

We consider the problem of fairly allocating an infinitely divisible commodity among agents with single-peaked preferences. First, we examine the implications of the requirement that a change in the population affect all agents that are present before and after the change in the same direction. We show that this requirement is met by no selection from the no-envy solution. In the face of this impossibility, we limit our attention to changes that are not so “disruptive”, in the following sense: if initially there is not enough to bring all agents to their satiation points, then this still is the case after the change, and if initially there is so much that agents have to be brought beyond their satiation points, then again, this remains the case. The requirement is that such changes affect all agents that are present before and after the change in the same direction. Our main result is that there is essentially only one selection from the envy-free and efficient solution satisfying this property. It is the solution known as the “uniform” rule.