cssi/SciSciGPT-SciSciNet huggingface dataset:
The importance of Green Chemistry in Process Research and Development

Green Chemistry or Sustainable Chemistry is defined by the Environmental Protection Agency as “the design of chemical products that reduce or eliminate the use of hazardous substances” In recent years there is a greater societal expectation that chemists and chemical engineers should produce greener and more sustainable chemical processes and it is likely that this trend will continue to grow over the next few decades. This tutorial review gives information on solvents and solvent selection, basic environmental metrics collection and three industrial case histories. All three case histories involve enzymatic chemistry. Pregabalin (Lyrica®) is produced using a lipase based resolution and is extremely unusual in that all four manufacturing steps to make pregabalin are performed in water. Sitagliptin (Januvia®) uses a transaminase in the final chemical step. Finally a rosuvastatin (Crestor®) intermediate is produced using a deoxy ribose aldolase (DERA) enzyme in which two carbon–carbon bonds and two chiral centres are formed in the same process step.
Domain structure of a Reggeon field theory with three couplings

The high-energy behavior of a Reggeon field theory with a three-Reggeon coupling and two four-Reggeon couplings is considered. Using the renormalization- group equations which are calculated in lowest order by Bardeen et al. for this model, a study is made of the way the couplings evolve to the fixed points in the high-energy limit. It is found that there are three fixed points (plus a fourth at infinity) to which the couplings can evolve. The space of couplings divides into four domains, two of which are two-dimensional and two of which are three- dimensional. The couplings in one of the three-dimensional domains are found to evolve to infinity and the couplings in the other three domains are found to evolve to the fixed-point couplings. The boundaries of these domains and some characteristic evolution curves are shown. The implications of the domain structure of the model are discussed. (AIP)
Use of 1,2-dichloro 4,5-dicyanoquinone (DDQ) for cleavage of the 2-naphthylmethyl (NAP) group

Abstract The 2-naphthylmethyl (NAP) group is a versatile group for protection of hydroxyl functions. It is stable to 4% TFA in CHCl 3 , hot 80% HOAc–H 2 O, SnCl 2 –AgOTf and HCl–EtOH, but it can readily be removed with DDQ in CH 2 Cl 2 .
Morphology of fluvial networks on Titan: Evidence for structural control

Abstract Although Titan’s surface shows clear evidence of erosional modification, such as fluvial incision, evidence for tectonism has been less apparent. On Earth, fluvial networks with strongly preferred orientations are often associated with structural features, such as faults or joints, that influence flow or erodibility. We delineated and classified the morphologies of fluvial drainages on Titan and discovered evidence of structural control. Fluvial networks were delineated both on synthetic aperture radar (SAR) images covering ∼40% of Titan from the Cassini Titan Radar Mapper up through T71 and on visible light images of the Huygens landing site collected by the Descent Imager/Spectral Radiometer (DISR). The delineated networks were assigned to one of three morphologic classes—dendritic, parallel or rectangular—using a quantitative terrestrial drainage pattern classification algorithm modified for use with Titan data. We validated our modified algorithm by applying it to synthetic fluvial networks produced by a landscape evolution model with no structural control of drainage orientations, and confirmed that only a small fraction of the networks are falsely identified as structurally controlled. As a second validation, we confirmed that our modified algorithm correctly classifies terrestrial networks that are classified in multiple previous works as rectangular. Application of this modified algorithm to our Titan networks results in a classification of rectangular for one-half of the SAR and DISR networks. A review of the geological context of the four terrestrial rectangular networks indicates that tensional stresses formed the structures controlling those terrestrial drainages. Based on the similar brittle response of rock and cryogenic ice to stress, we infer that structures formed under tension are the most likely cause of the rectangular Titan networks delineated here. The distribution of these rectangular networks suggests that tensional stresses on Titan may have been widespread.
Fuel effects on gas turbine combustion-liner temperature, pattern factor, and pollutant emissions

An anaytical study is made of the substantial body of experimental data acquired during recent Wright Patterson Aero Propulsion Laboratory sponsored programs on the effects of fuel properties on the performance and reliability of several gas turbine combustors, including J79-17A, J79 17C (Smokeless), F101, TF41, TF39, J85, TF33, and F100 Quantitative relationships are derived between certain key aspects of combustion, notably liner wall temperature, pattern factor, and exhaust emissions, and the relevant fuel properties, combustor design features and combustor operating conditions It is concluded that fuel chemistry, as indicated by hydrogen content and/or aromatics content, has a significant effect on flame radiation and liner wall temperature, but only a slight effect on the emissions of carbon monoxide (CO) and oxides of nitrogen (NOX) The physical properties that govern atomization quality and evaporation rates affect CO emissions, but other important performance parameters, such as NO X emissions and liner wall temperature, are sensibly independent of physical properties over the range of fuels studied
Fluid mixing from viscous fingering.

Mixing efficiency at low Reynolds numbers can be enhanced by exploiting hydrodynamic instabilities that induce heterogeneity and disorder in the flow. The unstable displacement of fluids with different viscosities, or viscous fingering, provides a powerful mechanism to increase fluid-fluid interfacial area and enhance mixing. Here we describe the dissipative structure of miscible viscous fingering, and propose a two-equation model for the scalar variance and its dissipation rate. Our analysis predicts the optimum range of viscosity contrasts that, for a given P\'eclet number, maximizes interfacial area and minimizes mixing time. In the spirit of turbulence modeling, the proposed two-equation model permits upscaling dissipation due to fingering at unresolved scales.
Heritability of age at natural menopause in the Framingham Heart Study.

Background: Twin registries and family history studies provide evidence that genetic factors contribute to the onset of menopause, but heritability estimates in population-based samples are limited. We sought to estimate heritability of age at natural menopause in women participating in the multigenerational Framingham Heart Study, a community-based epidemiological study. Methods: A total of 1500 original cohort and 932 offspring cohort women from 1296 extended families reported a natural menopause defined as the natural cessation of menses for 1 yr or more. Correlation coefficients were calculated using family correlations in Statistical Applications for Genetic Epidemiology for mother-daughter, sister-sister, and aunt-niece pairs. Heritability was estimated using variance-components methods in the Sequential Oligogenic Linkage Analysis Routines (SOLAR) computer package. Covariates in the multivariable models included generation, number of cigarettes smoked, body mass index, and parity. Results: The mean...
Distinguishing drug toxicity syndromes from medical diseases: a QMR computer-based approach

Abstract Drug effect can mimic a wide variety of diseases. Experts note that adverse drug reactions (ADRs) have become the ‘greatest imitator’ of disease in clinical medicine. Quick Medical Reference (QMR) is a decision support system providing diagnostic data about more than 600 medical diseases. Currently, QMR contains only limited drug information. Just as physicians have difficulty diagnosing ADRs, QMR has similar problems in differentiating natural disease manifestations from drug toxicity syndromes. To remedy this problem, two prototype Drug Syndromes (DS), Carbamazepine Toxicity and Penicillin Toxicity, were incorporated into the QMR Knowledge Base (KB). Using detailed case reports, we demonstrated that a DS-augmented version of QMR was successful in discriminating these DS from the other diseases in QMR's KB. The addition of DS significantly improves QMR's diagnostic performance in cases in which some of the pathologic features are the consequence of drugs.
TrustedDB: A Trusted Hardware-Based Database with Privacy and Data Confidentiality

Traditionally, as soon as confidentiality becomes a concern, data are encrypted before outsourcing to a service provider. Any software-based cryptographic constructs then deployed, for server-side query processing on the encrypted data, inherently limit query expressiveness. Here, we introduce TrustedDB, an outsourced database prototype that allows clients to execute SQL queries with privacy and under regulatory compliance constraints by leveraging server-hosted, tamper-proof trusted hardware in critical query processing stages, thereby removing any limitations on the type of supported queries. Despite the cost overhead and performance limitations of trusted hardware, we show that the costs per query are orders of magnitude lower than any (existing or) potential future software-only mechanisms. TrustedDB is built and runs on actual hardware, and its performance and costs are evaluated here.
Invasion of the Giant Gravitons from Anti-de Sitter Space

It has been known for some time that the AdS/CFT correspondence predicts a limit on the number of single particle states propagating on the compact spherical component of the AdS × S geometry. The limit is called the stringy exclusion principle. The physical origin of this effect has been obscure but it is usually thought of as a feature of very small distance physics. In this paper we will show that the stringy exclusion principle is due to a surprising large distance phenomenon. The massless single particle states become progressively less and less point-like as their angular momentum increases. In fact they blow up into spherical branes of increasing size. The exclusion principle is simply understood as the condition that the particle should not be bigger than the sphere that contains it.
Learning structured representations

Abstract SHRUTI is a connectionist model that demonstrates how a network of neuron-like elements can encode a large body of semantic, episodic, and causal knowledge, and rapidly make decisions and perform explanatory and predictive reasoning. To further ground this model in the functioning of the brain it must be shown that components of the model can be learned in a neurally plausible manner. Previous work has already demonstrated the rapid learning of episodic facts via cortico-hippocampal interactions. Here we discuss how other SHRUTI representations such as causal rules, statistical and semantic knowledge, and categories might be learned.
Error-trellis syndrome decoding techniques for convolutional codes

In the paper, a new error-trellis syndrome decoding technique for convolutional codes is developed. This algorithm is specialised then to the entire class of systematic convolutional codes. Finally, this algorithm is applied to the high-rate Wyner-Ash convolutional codes. A special example of the one-error-correcting Wyner-Ash code, a 3/4 rate code, is treated in the paper. The error-trellis syndrome decoding method applied to this example shows in detail how much more efficient syndrome decoding is than, say, Viterbi decoding would be if applied to the same problem. For standard Viterbi decoding, 64 states would be required, whereas in the example only seven states are needed. Also, within the seven states required for decoding, many less transitions are needed between the states.
The boronic acid mannich reaction: A new method for the synthesis of geometrically pure allylamines

Abstract Reaction of vinyl boronic acids with the adducts of secondary amines and paraformaldehyde gives tertiary allylamines with the same geometry. This simple and practical method was used for the synthesis of geometrically pure naftifine, a potent antifungal agent.
High temperature induces reversible silence in Aplysia R15 bursting pacemaker neuron

Abstract 1. 1. The effects of heat on the activity of the endogenously bursting neurosecretory cell R15 in Aplysia were examined over the temperature range from 23 to 37°C. 2. 2. Interburst interval decreased from 14.1 ± 3.0 sec at room temperature to 6.6 ± 0.95 sec at about 30°C before rising to 17.3 ± 4.1 sec at about 33°C. Burst duration, spike height, and number of spikes per burst all decreased with increasing temperature. 3. 3. At 35°C spontaneous bursting activity ceased, and 9 out of 10 cells remained silent as long as temperature was maintained above this level. Most neurons resumed bursting activity upon subsequent cooling, although changes in spontaneous activity from the pre-heating period were evident. 4. 4. After-effects of heating, observed within 1 to 3 hr of the heat stress, included lengthening of the interburst interval, decrease in the number of spikes per burst, increase in burst duration, increase in membrane oscillation and, in 3 of 10 cells, failure to permanently recover endogenous activity. The magnitude of these after-effects was greater in cells heated for > 15 minutes than in cells heated for a shorter time.
A strategy for SETI observations at Arecibo Observatory

Abstract We propose that the 100 ft diameter antenna at Los Canos, near Arecibo, be used with the 1000 ft Arecibo telescopes to reduce the effects of RF interference in SETI observations. Because of its large collecting area, the 1000 ft telescope at Arecibo is a prime instrument for SETI. On the other hand, RFI will limit its usefulness. Because any ETI signal will be of extraterrestrial origin, its detection at the larger antenna will be accompanied by a similar detection in the smaller antenna, at a lower level, if it is pointed in the same direction. A detector which multiplies the outputs of the two antennas, an interferometer, can serve as an anticoincidence discriminator against RF interference. We describe a strategy for observations in which such an interferometer can operate either in parallel with a single detector at the large telescope, or in sequence to verify at ETI detection. The recent survey studies of RFI at the Goldstone Observatory (Klein et al. , 1987, this volume) provide examples of the nature of the interference that may be encountered at Arecibo. We show that the multiplying detector can reduce the effects of RF interference by between 20 and 30 dB.
Human factors audit programs for nonrepetitive tasks

In order to provide aircraft maintenance and inspection personnel with a rapid means of locating the human–system mismatches that can lead to errors, two human factors audits were developed. Both the inspection audit and the maintenance audit are in the form of measurement checklists, usable either on a portable computer or in paper form. Both were tested for reliability and modified until high reliability was achieved. Both were validated against human factors professionals, with both programs identifying more mismatches than the practitioners. The programs are in use at an airline as a complement to existing safety and quality audit systems. © 1998 John Wiley & Sons, Inc.
Feed, Speed, and Torque Controllers for Drilling

The design and implementation of feed, speed, and torque controllers for drilling is discussed. Dynamic models of the feedrate drive and spindle motors were developed using experimental data and least squares estimation. These dynamic models were subsequently used to design closed loop feed and speed controllers, which allow for independent control of the machining feed and speed during drilling. They effectively track constant, as well as step-change, command references. Subsequently, the feed controller was used to develop a dynamic model between feed and torque, and then was cascaded with a torque control loop. The dynamic modeling and subsequent closed loop controller design and performance are described.
Weak visibility queries of line segments in simple polygons

Given a simple polygon P in the plane, we present new data structures for computing the weak visibility polygon from any query line segment in P. We build a data structure in O ( n ) time and space that can compute the visibility polygon for any query line segment s in O ( k log ? n ) time, where k is the size of the visibility polygon of s and n is the number of vertices of P. Alternatively, we build a data structure in O ( n 3 ) time and space that can compute the visibility polygon for any query line segment in O ( k + log ? n ) time. In order to develop these data structures, we obtain many other results that may be interesting in their own right.
The Interaction of Carbonyl Groups with Substituents

The carbonyl group is probably the most important functional group in organic chemistry, and its properties are strongly affected by substituents. This Account will be concerned with the modes of interaction between carbonyl groups and substituents, and how these interactions are manifested in the properties of the compounds containing this group. A comparison will be made between carbonyl groups and related groups, such as thiocarbonyl. The interaction of carbonyl groups with substituents has usually been described in terms of π electron interactions such as “amide resonance”. However, substituents may affect carbonyl groups in several different ways. They may withdraw or donate electron density via the σ bond, depending on their electronegativity. One of the important features of the carbonyl group is the difference in electronegativity between carbon and oxygen, which leads to both σ and π electron transfer from C to O and to a positively charged carbon. As a result, substituents that have lone pairs may also transfer π electron density to the electron-deficient carbon. Finally, if the atom of the substituent that is attached to the carbonyl group bears a partial charge, it will lead to a Coulombic interaction with the positively charged carbon. All of these modes of interaction have been found. There are three basic ways in which the energetics of the interaction of a carbonyl group with a substituent may be examined. The first makes use of a group-transfer reaction such as
Numerical weather prediction

Publisher Summary One of the prerequisites to forecast weather by means of physical laws is a system for quick and accurate computation, as a truly tremendous amount of arithmetic is involved to obtain a numerical solution. By removing this obstacle, computing machines are making numerical weather prediction a practical possibility. The extent and quality of the data available to define the initial state of the atmosphere is clearly important in any method of weather forecasting. Most weather phenomena are associated with motions that are almost incompressible, almost hydrostatic, and almost geostrophic in character. The chapter describes a method whereby the sensitivity can be reduced, but the adequacy of the initial data is still of vital concern. The chapter provides equations suitable for numerical weather prediction and justifies the important approximations of hydrostatic and geostrophic balance, and friction and non-adiabatic effects. The two systems of equations that form the basis for numerical weather prediction are the hydrostatic system (frequently called the “primitive equations”) and the geostrophic system. The chapter also accounts for marching problems and computational stability and inversion of elliptic operators in the geostrophic system. Finally, the results of numerical predictions including the results of geostrophic forecasts and non-geostrophic forecasts are provided.
The Data Locality of Work Stealing

This paper studies the data locality of the work-stealing scheduling algorithm on hardware-controlled shared-memory machines, where movement of data to and from the cache is solely controlled by the hardware. We present lower and upper bounds on the number of cache misses when using work stealing, and introduce a locality-guided work-stealing algorithm and its experimental validation. As a lower bound, we show that a work-stealing application that exhibits good data locality on a uniprocessor may exhibit poor data locality on a multiprocessor. In particular, we show a family of multithreaded computations G n whose members perform Θ(n) operations (work) and incur a constant number of cache misses on a uniprocessor, while even on two processors the total number of cache misses soars to Ω(n) . On the other hand, we show a tight upper bound on the number of cache misses that nested-parallel computations, a large, important class of computations, incur due to multiprocessing. In particular, for nested-parallel computations, we show that on P processors a multiprocessor execution incurs an expected O (C ⌉m/s;⌈PT ∞more misses than the uniprocessor execution. Here m is the execution time of an instruction incurring a cache miss, s is the steal time, C is the size of cache, and T ∈ fty is the number of nodes on the longest chain of dependencies. Based on this we give strong execution time bounds for nested-parallel computations using work stealing.} For the second part of our results, we present a locality-guided work-stealing algorithm that improves the data locality of multithreaded computations by allowing a thread to have an affinity for a processor. Our initial experiments on iterative data-parallel applications show that the algorithm matches the performance of static-partitioning under traditional work loads but improves the performance up to 50% over static partitioning under multiprogrammed work loads. Furthermore, locality-guided work stealing improves the performance of work stealing up to 80%.
Peptidomics: Identification and quantification of endogenous peptides in neuroendocrine tissues

Neuropeptides perform a large variety of functions as intercellular signaling molecules. While most proteomic studies involve digestion of the proteins with trypsin or other proteases, peptidomics studies usually analyze the native peptide forms. Neuropeptides can be studied by using mass spectrometry for identification and quantitation. In many cases, mass spectrometry provides an understanding of the precise molecular form of the native peptide, including post-translational cleavages and other modifications. Quantitative peptidomics studies generally use differential isotopic tags to label two sets of extracted peptides, as done with proteomic studies, except that the Cys-based reagents typically used for quantitation of proteins are not suitable because most peptides lack Cys residues. Instead, a number of amine-specific labels have been created and some of these are useful for peptide quantitation by mass spectrometry. In this review, peptidomics techniques are discussed along with the major findings of many recent studies and future directions for the field.
Turbulent transport reduction by zonal flows : Massively parallel simulations

Three-dimensional gyrokinetic simulations of microturbulence in magnetically confined toroidal plasmas with massively parallel computers showed that, with linear flow damping, an asymptotic residual flow develops in agreement with analytic calculations. Nonlinear global simulations of instabilities driven by temperature gradients in the ion component of the plasma support the view that turbulence-driven fluctuating zonal flows can substantially reduce turbulent transport. Finally, the outstanding differences in the flow dynamics observed in global and local simulations are found to be due to profile variations.
A law of large numbers for finite-range dependent random matrices

We consider random Hermitian matrices in which distant above-diagonal entries are independent but nearby entries may be correlated. We find the limit of the empirical distribution of eigenvalues by combinatorial methods. We also prove that the limit has an algebraic Stieltjes transform by an argument based on dimension theory of Noetherian local rings. © 2008 Wiley Periodicals, Inc.
Improved protocol for the formation of N-(p-nitrobenzyloxy)aminoalditol derivatives of oligosaccharides

Abstract An improved procedure has been developed for the rapid derivatization of oligosaccharides with UV-detectable p-nitrobenzylhydroxylamine (PNB). The improved conditions used result in quantitative derivatization of neutral oligosaccharides. Sialylated oligosaccharides can also be quantitatively PNB-derivatized without detectable desialylation. Of the oligosaccharides tested, only the derivatization of oligogalactosyluronic acids was incomplete (yield ∼ 70%). PNB-derivatization of tamarind seed xyloglucan oligosacccharides results in products with improved chromatographic properties during HPAEC. These PNB derivatives were also subjected to hydrophilic interaction chromatography (HILIC) and analyzed by on-line LC-MS. On-line LC-MS is readily usable with HILIC, as this chromatographic technique does not require salt-containing solvents. Approximately 10 pmol of a PNB-derivatized oligosaccharide can be identified and quantitated utilizing this method.
NON-THERMAL EMISSION FROM THE PHOTOSPHERES OF GAMMA-RAY BURST OUTFLOWS. I. HIGH-FREQUENCY TAILS

We study the spectrum of high-frequency radiation emerging from mildly dissipative photospheres of long-duration gamma-ray burst outflows. Building on the results of recent numerical investigations, we assume that electrons are heated impulsively to mildly relativistic energies by either shocks or magnetic dissipation at Thomson optical depths of several and subsequently cool by inverse Compton, scattering off the thermal photons of the photosphere. We show that even in the absence of magnetic field and non-thermal leptons, inverse Compton scattering produces power-law tails that extend from the peak of the thermal radiation, at several hundred keV, to several tens of MeV, and possibly up to GeV energies. The slope of the high-frequency power law is predicted to vary substantially during a single burst, and the model can easily account for the diversity of high-frequency spectra observed by BATSE. Our model works in baryonic as well as in magnetically dominated outflows, as long as the magnetic field component is not overwhelmingly dominant.
A Three-Dimensional Framework with Accessible Nanopores: RbCuSb2Se4⋅H2O

Semiconductor properties are exhibited by the hydrothermally synthesized title compound, whose channels are occupied by Rb+ ions and water molecules. In topotactic reactions the exchange of the Rb+ ions for smaller alkali metal ions demonstrates the high mobility of the cations and may determine other interesting properties.
SN 2006bt: A PERPLEXING, TROUBLESOME, AND POSSIBLY MISLEADING TYPE Ia SUPERNOVA

SN 2006bt displays characteristics unlike those of any other known Type Ia supernova (SN Ia). We present optical light curves and spectra of SN 2006bt which demonstrate the peculiar nature of this object. SN 2006bt has broad, slowly declining light curves indicative of a hot, high-luminosity SN, but lacks a prominent second maximum in the i band as do low-luminosity SNe Ia. Its spectra are similar to those of low-luminosity SNe Ia, containing features that are only present in cool SN photospheres. Light-curve fitting methods suggest that SN 2006bt is reddened by a significant amount of dust; however, it occurred in the outskirts of its early-type host galaxy and has no strong Na D absorption in any of its spectra, suggesting a negligible amount of host-galaxy dust absorption. C II is possibly detected in our pre-maximum spectra, but at a much lower velocity than other elements. The progenitor was likely very old, being a member of the halo population of a galaxy that shows no signs of recent star formation. SNe Ia have been very successfully modeled as a one-parameter family, and this is fundamental to their use as cosmological distance indicators. SN 2006bt is a challenge to that picture,more » yet its relatively normal light curves allowed SN 2006bt to be included in cosmological analyses. We generate mock SN Ia data sets which indicate that contamination by similar objects will both increase the scatter of a SN Ia Hubble diagram and systematically bias measurements of cosmological parameters. However, spectra and rest-frame i-band light curves should provide a definitive way to identify and eliminate such objects.« less
Identification of the Infrared Counterpart to a Newly Discovered X-Ray Source in the Galactic Center

We present first results of a campaign to find and identify new compact objects in the Galactic Center. Selecting candidates from a combination of Chandra and 2MASS survey data, we search for accretion disk signatures via infrared spectroscopy. We have found the infrared counterpart to the Chandra source CXO J174536.1-285638, the spectrum of which has strong Br and HeI emission. The presence of CIII, NIII, and HeII indicate a binary system. We suspect that the system is some form of high-mass binary system, either a high-mass X-ray binary or a colliding wind binary. Subject headings: accretion, accretion disks, binaries:X-ray, infrared:stars, X-ray:stars,
THE ORIGINS AND EVOLUTIONARY STATUS OF B STARS FOUND FAR FROM THE GALACTIC PLANE. I. COMPOSITION AND SPECTRAL FEATURES

The existence of faint blue stars far above the Galactic plane that have spectra that are similar to nearby Population I B stars presents several interesting questions. Among them are the following: Can a Population I B star travel from the disk to a position many kiloparsecs above the plane in a relatively short main-sequence lifetime? Is it possible that single massive star formation is occurring far from the Galactic plane? Are these objects something else masquerading as main-sequence B stars? This paper (the first of two) analyzes the abundances of a sample of these stars and reveals several that are chemically similar to nearby Population I B stars, whereas others clearly have abundance patterns more like those expected in blue horizontal-branch (BHB) or post–asymptotic giant branch stars. Several of those with old evolved star abundances also have interesting features of note in their spectra. We also consider why this sample does not have any classical Be stars and identify at least two nearby solar-metallicity BHB stars.
Vacuum stability, perturbativity, and scalar singlet dark matter

We analyze the one-loop vacuum stability and perturbativity bounds on a singlet extension of the Standard Model (SM) scalar sector containing a scalar dark matter candidate. We show that the presence of the singlet-doublet quartic interaction relaxes the vacuum stability lower bound on the SM Higgs mass as a function of the cutoff and lowers the corresponding upper bound based on perturbativity considerations. We also find that vacuum stability requirements may place a lower bound on the singlet dark matter mass for given singlet quartic self coupling, leading to restrictions on the parameter space consistent with the observed relic density. We argue that discovery of a light singlet scalar dark matter particle could provide indirect information on the singlet quartic self-coupling.
An X-Ray Survey of Very Young Stellar Objects

?????Several recent studies with the ROSAT and ASCA satellites have reported X-ray emission from Class I protostars. We present here an X-ray survey of 156 protostellar sources using archived ROSAT PSPC pointed observations. Targets are drawn from four samples: low-temperature objects in nearby star forming regions, Herbig-Haro outflow sources, CO outflow sources, and Class 0 embedded protostars. Over 90% are not detected at the 3 ? limit over the 1.0?2.4 keV band, with upper limits of 0.1?40 counts ks-1 corresponding to log LX 28?33 ergs s-1. Of the 11 detected objects, 10 are either Class II or III stars or previously detected Class I protostars. One new Class I source, Ced 110 IRS 6 in the Chamaeleon I cloud, is found. The X-ray luminosity function of protostars is calculated, but is quite uncertain. We conclude that X-ray emission from protostars has a broad luminosity function and that very X-ray luminous (LX 1031 ergs s-1) protostars are rare.
System of systems perspective on risk: towards a unified concept

Many systems and projects that concern systems engineers, engineering managers, and business managers today can be defined as system of systems (SoS), which are described as ambiguous, uncertain and dynamic, among others. In addition to the traditional view on risk identification, analysis and management, the concept of risk should be considered with respect to these systems of systems. The purpose of this paper is to analyse both fundamental concepts and recent publications in system of systems, business and engineering management, as well as risk analysis, modelling, and management for the purpose of better describing the concept of risk with respect to system of systems. The ultimate goal is to provide engineering and business managers the necessary perspective on the concept of risk and its management for the next generation of systems - including various descriptions of risk and discussion of the relevance of properties of system of systems to sustainable management of risks in engineered systems. To achieve a truly sustainable management of risk, there has to be a change in paradigm from a traditional description of risk to that of a more holistic perspective.
The binding energy and bonding in dialane.

The binding energy of dialane, Al2H6, has been measured using mass spectrometric techniques to be 33 ± 5 kcal/mol. This represents the first measurement of the thermochemical properties of dialane, which has only recently been observed in low-temperature matricies. High-level quantum mechanical calculations give a binding energy in agreement with the measured value. Experimental and quantum mechanical calculations show that dialane is chemically similar to diborane, B2H6, even though the bonding for these two systems shows significant differences.
Synthetic Utility of Yeast Hexokinase. Substrate Specificity, Cofactor Regeneration, and Product Isolation.

Yeast hexokinase (EC 2.7.1.1) catalyzes the phosphorylation of pyranose and furanose analogs of glucose at 0.01−125% of the rate of glucose. The enzyme is highly tolerant of structural changes at C-2 and C-3 of glucopyranose and less tolerant of changes at C-1 and C-4. Preparative phosphorylations were performed on compounds having 0.01−100% of the activity of glucose, using phosphoenolpyruvate and pyruvate kinase to regenerate ATP. The effects of inhibition of hexokinase by phosphoenolpyruvate and acetyl phosphate on cofactor regeneration are discussed.
Sustained resonance: a binary system perturbed by gravitational radiation

The general phenomena associated with sustained resonance are studied in this paper in connection with relativistic binary pulsars. We represent such a system by two point masses in a Keplerian binary system that evolves via gravitational radiation damping as well as an external tidal perturbation. For further simplification, we assume that the external tidal perturbation is caused by a normally incident circularly polarized monochromatic gravitational wave. In this case, the second-order partially averaged equations are studied and a theorem of C Robinson is employed to prove that for certain values of the physical parameters resonance capture followed by sustained resonance is possible in the averaged system. We conjecture that sustained resonance can occur in the physical system when the perturbing influences nearly balance each other.
Sampling binary contingency tables with a greedy start

We study the problem of counting and randomly sampling binary contingency tables. For given row and column sums, we are interested in approximately counting (or sampling) 0/1 n x m matrices with the specified row/column sums. We present a simulated annealing algorithm with running time O((nm)2D3d max log 5(n + m)) for any row/column sums, where D is the number of nonzero entries and dmax is the maximum row/column sum. In the worst case, the running time of the algorithm is O(n11 log 5n) for an n x n matrix. This is the first algorithm to directly solve binary contingency tables for all row/column sums. Previous work reduced the problem to the permanent, or restricted attention to row/column sums that are close to regular. The interesting aspect of our simulated annealing algorithm is that it starts at a nontrivial instance, whose solution relies on the existence of short alternating paths in the graph constructed by a particular Greedy algorithm.© 2006 Wiley Periodicals, Inc. Random Struct. Alg., 2007
CSP gaps and reductions in the lasserre hierarchy

We study integrality gaps for SDP relaxations of constraint satisfaction problems, in the hierarchy of SDPs defined by Lasserre. Schoenebeck [23] recently showed the first integrality gaps for these problems, showing that for MAX k-XOR, the ratio of the SDP optimum to the integer optimum may be as large as 2 even after Ω(n) rounds of the Lasserre hierarchy. We show that for the general MAX k-CSP problem, this ratio can be as large as 2k/2k - e when the alphabet is binary and qk/q(q-1)k - e when the alphabet size a prime q, even after Ω(n) rounds of the Lasserre hierarchy. We also explore how to translate gaps for CSP into integrality gaps for other problems using reductions, and establish SDP gaps for Maximum Independent Set, Approximate Graph Coloring, Chromatic Number and Minimum Vertex Cover. For Independent Set and Chromatic Number, we show integrality gaps of n/2O(√(log n log log n)) even after 2Ω(√(log n log log n)) rounds. In case of Approximate Graph Coloring, for every constant l, we construct graphs with chromatic number Ω(2l/2/l2), which admit a vector l-coloring for the SDP obtained by Ω(n) rounds. For Vertex Cover, we show an integrality gap of 1.36 for Ω(nδ) rounds, for a small constant δ. The results for CSPs provide the first examples of Ω(n) round integrality gaps matching hardness results known only under the Unique Games Conjecture. This and some additional properties of the integrality gap instance, allow for gaps for in case of Independent Set and Chromatic Number which are stronger than the NP-hardness results known even under the Unique Games Conjecture.
Polarization in Elastic Nucleon-Deuteron Scattering

An approximate $K$-matrix calculation of elastic nucleon-deuteron scattering is carried out including the effects of two-nucleon tensor forces. The results of these computations, which are carried out in the energy range from 11 to 40 MeV, are in reasonable agreement with the experimental nucleon polarizations and differential cross sections.
Stability of Satellites around Close-in Extrasolar Giant Planets

We investigate the long-term dynamical stability of hypothetical moons orbiting extrasolar giant planets. Stellar tides brake a planet's rotation and, together with tidal migration, act to remove satellites; this process limits the lifetimes of larger moons in extrasolar planetary systems. Because more massive satellites are removed more quickly than less massive ones, we are able to derive an upper mass limit for those satellites that might have survived to the present day. For example, we estimate that no primordial satellites with masses greater than 7 × 10-7 M⊕ (~70 km radius for ρ = 3 g cm-3) could have survived around the transiting planet HD 209458b for the age of the system. No meaningful mass limits can be placed on moons orbiting Jovian planets more than ~0.6 AU from their parent stars. Earthlike moons of Jovian planets could exist for 5 Gyr in systems where the stellar mass is greater than 0.15 M☉. Transits show the most promise for the discovery of extrasolar moons—we discuss prospects for satellite detection via transits using space-based photometric surveys and the limits on the planetary tidal dissipation factor Qp that a discovery would imply.
Smoothing Riemannian metrics with bounded Ricci curvatures in dimension four, II

This note is a continuation of the author’s paper (Li, Adv. Math. 223(6):1924–1957, 2010). We prove that if the metric g of a compact 4-manifold has bounded Ricci curvature and its curvature has no local concentration everywhere, then it can be smoothed to a metric with bounded sectional curvature. Here we don’t assume the bound for local Sobolev constant of g and hence this smoothing result can be applied to the collapsing case.
Efficient Parallel Programming with Linda

Linda is a coordination language inverted by David Gelernter at Yale University, which when combined with a computation language (like C) yields a high-level parallel programming language for MIMD machines. Linda is based on a virtual shared associative memory containing objects called tuples. Skeptics have long claimed that Linda programs could not be efficient on distributed memory architectures. In this paper, we address this claim by discussing C-Linda's performance in solving a particular scientific computing problem, the shallow water equations, and make comparisons with alternatives available on various shared and distributed memory parallel machines.
Anticipation and surprises in central bank interest rate policy : the case of the bundesbank

Market reaction to a change in official interest rates will depend on the extent to which the change is anticipated, and on how it is interpreted as a signal of future policy. In this paper, a technique is developed to separate the anticipated and unanticipated components of such changes, and applied to estimate the response of euro--deutsche mark interest rates to adjustments in the Bundesbank's Lombard and discount rates.
Regioselective Bromination of Fused Heterocyclic N-Oxides

A mild method for the regioselective C2-bromination of fused azine N-oxides is presented, employing tosic anhydride as the activator and tetra-n-butylammonium bromide as the nucleophilic bromide source. The C2-brominated compounds are produced in moderate to excellent yields and with excellent regioselectivity in most cases. The potential extension of this method to other halogens, effecting C2-chlorination with Ts2O/TBACl is also presented. Finally, this method could be incorporated into a viable one-pot oxidation/bromination process, using methyltrioxorhenium/urea hydropgen peroxide as the oxidant.
Molecular-Dynamics Simulation of Colloidal Nanoparticle Forces

Molecular-dynamics simulations are utilized to simulate solvation forces between two nanoparticles immersed in a Lennard−Jones liquid. Four different sizes and shapes of solvophilic nanoparticles are investigated. For nanoparticles at a fixed orientation, we find that the solvation forces oscillate between attraction and repulsion as the particle separation is increased. Small nanoparticles can rotate rapidly under the influence of solvation forces and achieve relative orientations that minimize the free energy. Our results indicate that surface roughness can control nanoparticle alignment in a solvophilic colloidal suspension and that selective colloidal assemblies can be achieved by choosing nanoparticles with certain textures and/or shapes.
Terahertz quantum cascade lasers and video-rate THz imaging

The terahertz frequency range (1–10 THz) has long remained undeveloped, mainly due to the lack of compact, coherent radiation sources. Semiconductor electronic devices (such as transistors) are limited by the transient time and RC roll-off to below 1 THz. Conventional semiconductor photonic devices (such as bipolar laser diodes) are limited to above 10 THz even using small-gap lead-salt materials. Transitions between subbands in semiconductor quantum wells were suggested as a method to generate long wavelength radiation at customizable frequencies. The recently developed THz quantum-cascade lasers (QCL) hold great promise to bridge the so-called “THz gap” between conventional electronic and photonic devices.
Tight closure and linkage classes in Gorenstein rings

We study the relationship between the tight closure of an ideal and the sum of all ideals in its linkage class
Irreversibility, uncertainty and housing investment

Housing represents a form of “irreversible” investment. Theoretically, increased uncertainty should lower housing investment. Empirically, finding a proxy for uncertainty has proven problematic. Some recent papers have investigated the effect of uncertainty on real estate investment, with varying proxies for uncertainty and mixed results. This paper employs a technique used in modern macroeconomic studies, the Generalized Autoregressive Conditional Heteroskedasticity-in-Mean model, which has been shown to correspond as closely as any known measure to theoretical concepts of uncertainty. Results indicate that uncertainty indeed has a negative impact on housing starts.
An infinite family of Legendrian torus knots distinguished by cube number

Abstract For a knot K the cube number is a knot invariant defined to be the smallest n for which there is a cube diagram of size n for K . There is also a Legendrian version of this invariant called the Legendrian cube number . We will show that the Legendrian cube number distinguishes the Legendrian left hand torus knots with maximal Thurston–Bennequin number and maximal rotation number from the Legendrian left hand torus knots with maximal Thurston–Bennequin number and minimal rotation number.
Numerical Investigation of Flow in an Overexpanded Nozzle with Porous Surfaces

A new porous condition has been implemented in the PAB3D solver to simulate flow over porous surfaces. The newly added boundary condition is utilized to compute the flow field of a nonaxisymmetric, convergent-divergent nozzle incorporating porous cavities for shock-boundary layer interaction control. The nozzle has an expansion ratio (exit area/throat area) of 1.797 and a design nozzle pressure ratio (NPR) of 8.78. The flow fields for a baseline nozzle (no porosity) and for a nozzle with porous surfaces (10% porosity ratio) are computed for NPR varying from 2.01 to 9.54. Computational model results indicate that the overexpanded nozzle flow is dominated by shock-induced boundary-layer separation. Porous configurations are capable of controlling off-design separation in the nozzle by encouraging stable separation of the exhaust flow. Computational simulation results, wall centerline pressure, Mach contours, and thrust efficiency ratio are presented and discussed. Computed results are in excellent agreement with experimental data.
An effective method for measurement and analysis of system software performance

The performance measurement and analysis of software operating systems which extend basic computing machinery is discussed. The description of an external monitoring technique which facilitates the correlation of hardware events with software functions without the need for software monitors is presented. A time related Event is defined to provide the basis for the technique used to implement the monitor system. In addition, Event analysis methods are introduced which allow a software system execution profile to be constructed.
Hourly index return autocorrelation and conditional volatility in an EAR–GJR-GARCH model with generalized error distribution

Abstract We study the autocorrelation and conditional volatility of the hourly Dow Jones Industrial Index return data from October 1974 to September 2002 using an exponential asymmetric AR–GARCH specification with a generalized error distribution. Our findings document a positive autocorrelation in hourly return data in the early years of the sampling period, but the autocorrelation turns negative after 1986 and the negative shock causes more impact on the conditional volatility. This latter period evidence stands in contrast to prior findings employing lower frequency and/or earlier year data. In addition, our results present some evidence of a negative relation between autocorrelation and conditional volatility before 1986 (albeit weaker than prior findings), but this negative relationship disappears after 1986.