cssi/SciSciGPT-SciSciNet huggingface dataset:
On Ambiguities in the Interpretation of Game Trees

Abstract Piccione and Rubinstein have pointed out ambiguities in the interpretation of games of imperfect recall. They claim that a player in such a game may be time inconsistent. Here, it is argued that the apparent time inconsistency arises from implicit assumptions regarding what the player knows when he reconsiders his strategy, what he will remember if he changes his strategy, and how the node at which reconsideration takes place is chosen. A model is proposed that allows us—indeed, almost forces us—to make these issues explicit. Once these issues are made explicit, time inconsistency seems less inconsistent. Journal of Economic Literature Classification Numbers: C70, D80.
Cache-miss-initiated prefetch in mobile environments

Prefetching has been widely used to improve system performance in mobile environments. Since prefetching consumes system resources, such as bandwidth and power, it is important to consider the system overhead when designing prefetching schemes. In this paper, we propose a cache-miss-initiated prefetch (CMIP) scheme to address this issue. The CMIP scheme relies on two prefetch sets: the always-prefetch set and the miss-prefetch set. The always-prefetch set consists of the data that should always be prefetched if it is possible. The miss-prefetch set consists of the data that are closely related to the cache-missed data item. When a cache miss happens, instead of sending an uplink request to only ask for the cache-missed data item, the client requests several data items, which are within the miss-prefetch set, to reduce future cache misses. Note that the client can ask for more than one data item by an uplink request with very little additional cost. Thus, prefetching several data items in one uplink request can save additional uplink requests. We propose novel algorithms to mine the association rules and use them to construct the prefetch sets. Detailed experiments are used to evaluate the performance of the proposed scheme. Compared to the UIR scheme [G. Cao, A scalable low-latency cache invalidation strategy for mobile environments, IEEE Transactions on Knowledge and Data Engineering 15(5) (2003)] and the UIR scheme without prefetch, our CMIP scheme can greatly improve the system performance in terms of cache hit ratio, reduced uplink requests and additional traffic.
Synthesis of thiol-derivatized ferrocene-porphyrins for studies of multibit information storage

One approach toward storage of multiple bits of information at the molecular level requires the construction of molecular architectures comprised of multiple redox-active units. Four new ferrocene−porphyrins have been synthesized to investigate questions concerning (1) the scope of redox-active molecules that can be employed in molecular information-storage schemes and (2) writing/reading rates as well as retention of charge in redox-active units located at different sites in a molecular architecture. Three of the ferrocene−porphyrins have linkers of different lengths between the ferrocene and porphyrin. The fourth ferrocene−porphyrin has two ferrocenes positioned at the lateral sites on the porphyrin. The latter architecture is designed to provide a shorter distance between the electroactive surface and the ferrocene while maintaining an upright orientation of the porphyrin. Each ferrocene−porphyrin affords three cationic oxidation states (ferrocene monocation, porphyrin monocation, porphyrin dication) i...
Is the vacuum stable

Abstract The experimental data, as well as theoretical considerations allow (and, in some cases, require the Universe at present to rest in a false vacuum, whose approximate stability imposes constraints on the model parameters. Under very general and mild conditions, the Universe would have ended up in the standard vacuum even if the potential has deeper minima, provided there was a period in which the temperature was ≳ 1 TeV. In many cases, the zero temperature tunneling rate is much smaller than the inverse age of the Universe. Future experiments may reveal that the physical vacuum is not entirely stable. Implications for the cosmological constant are discussed.
Reflectivity Difference Spectra of GaAs and ZnSe (100) Surfaces

Using a photoelastic modulator in the optical-bridge configuration, the reflectivity difference was obtained for GaAs and ZnSe (100) surfaces over the photon energy range from 1.5 eV to 6 eV with various azimuthal orientations of the surface. The RD data of GaAs (100) are similar to previously reported data. The RD data of ZnSe (100) are larger by an order of magnitude than those of GaAs (100), possibly due to the larger ionicity of Zn and Se atoms. The distinctive critical point structures and interference patterns shown in the RD spectra of ZnSe (100) suggest that the data, if obtained in real time, could be used to determine the alloy composition, thickness and temperature during growth. The RD data are analyzed using models proposed by Aspnes. The results indicate that the major contribution to the RD spectra of ZnSe (100) are from the surface local field unlike the RD spectra of GaAs (110), whose major contribution is from the bulk spatial distribution.
Dynamical Masses in Luminous Infrared Galaxies

We have studied the dynamics and masses of a sample of 10 nearby luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs, respectively) using 2.3 μm 12CO-absorption line spectroscopy and near-infrared H- and Ks-band imaging. By combining velocity dispersions derived from the spectroscopy, disk scale lengths obtained from the imaging, and a set of likely model density profiles, we calculate dynamical masses for each LIRG. For the majority of the sample, it is difficult to reconcile our mass estimates with the large amounts of gas derived from millimeter observations and from a standard conversion between 12CO emission and H2 mass. Our results imply that LIRGs do not have huge amounts of molecular gas (1010-1011 M☉) at their centers and support previous indications that the standard conversion of 12CO to H2 probably overestimates the gas masses and cannot be used in these environments. This in turn suggests much more modest levels of extinction in the near-infrared for LIRGs than previously predicted (AV ~ 10-20 vs. AV ~ 100-1000). The lower gas mass estimates indicated by our observations imply that the star formation efficiency in these systems is very high and is triggered by cloud-cloud collisions, shocks, and winds rather than by gravitational instabilities in circumnuclear gas disks.
Lewis acid-catalyzed [3+2]-cycloaddition reactions of allyl(cyclopentadienyl)iron(II) dicarbonyl with carbonyl compounds

Abstract ZnCl 2 catalyzes the [3+2]-cycloaddition of allyl(cyclopentadienyl)iron(II) dicarbonyl to carbonyl compounds to give tetrahydrofuran adducts.
LSS 2018: a double-lined spectroscopic binary central star with an extremely large reflection effect

LSS 2018, the central star of the planetry nebulae DS1, was found to be a double-lined spectroscopic binary with a period of 8.571 hours. Light variations with the same period were observed in U, B, and V; in the wavelength regions defined by the two IUE cameras; and in the strength of the CIII 4647 emission line. The light variations can be accurately predicted by a simple reflection effect, and an analysis of the light curves yields the angular diameter and effective temperature of the primary, the radii of the two stars in terms of their separation, and the inclination of the system. Analysis of the radial velocities then yields the masses of the two stars, their separation, the distance of the system, the absolute magnitude of the primary, and the size of the nebula.
Urovirulence Determinants in Escherichia Coli Strains Causing Prostatitis

To define the urovirulence properties of Escherichia coli strains producing prostatitis, E. coli strains isolated from men with acute (7 strains) or chronic (23) prostatitis were compared with E. coli isolates from women with pyelonephritis (30), acute cystitis (60), or complicated urinary tract infection (UTI; 30). Strains from prostatitis patients were significantly more likely to express hemolysin than were strains causing complicated UTI (73% vs. 43%; P = .02) and more often demonstrated hybridization with the cytotoxic necrotizing factor-1 (CNF-1) probe (63%) than did strains from women (44%-48%). P fimbrial expression was highest among pyelonephritis (73%) and prostatitis strains (53%) and lowest among E. coli from women with complicated UTI (23%) and cystitis (30%; P < .05, prostatitis strains vs. either of the latter 2 groups). Results suggest that E. coli strains producing prostatitis generally possess urovirulence profiles similar to those of strains from women with acute uncomplicated pyelonephritis and that hemolysin and CNF-1 are especially prevalent in prostatitis strains.
Theory of microemulsion glasses

We show that the tendency towards microphase separation in microemulsions can lead to the formation of a glassy state after sufficiently strong correlations between polar and hydrophobic regions have been established. Glassiness is predicted to occur above a critical volume fraction of surfactant molecules, which is determined by the length of the amphiphilic molecules. Our results are obtained by solving the dynamical equations for the correlation functions of the system and by using a replica approach.
Comparing Apples: Normalcy, Russia, and the Remaining Post-Socialist World

Shleifer and Treisman (2005) argue that Russia is a "normal country" but their benchmark for normalcy refers primarily to middle-income countries like Mexico and Argentina. Drawing on data from the World Bank and Transparency International, two economists explore this argument by placing Russia in a different context. Russia's experience is examined in comparison with other post-socialist transition countries sharing common political and economic histories with Russia, which have faced similar transition obstacles since communism's collapse. Russia's economic performance, media freedom, democracy, and corruption since transition are compared to these benchmarks in all other post-socialist countries since they began their transitions.
The Sand-Fly and Pellagra

For more than 200 years the etiology of pellagra has been a subject of serious inquiry. This problem, formerly an Old World question, now concerns us, and it still awaits solution. Though the disease is positively known to have existed in this country for less than thirty years, it is now found in almost one-half the states of the Union, becoming in the South a grave disorder. Briefly, it may be said that the causation of pellagra is purely conjectural. Since 1776, when the Patriotic Society of Milan offered a prize for the determination of the cause, an immense amount of work has been done by worthy investigators, but as yet its real cause is unknown. We do not know whether the disease is toxico-chemical, toxico-infectious or due to a specific infection by molds, bacteria, or protozoa. The solution of this problem has at various times been proclaimed, but sub'.T'eni,
Rhodium-mediated enantioselective cyclopropanation of allenes.

Reaction of monosubstituted allenes with aryldiazoacetate esters under dirhodium tetracarboxylate catalysis led to alkylidene cyclopropane products in 80−90% ee. Monosubstituted alkyl- and arylallene substrates gave 60−75% yield under standard conditions, while yields for 1,1-disubstituted allenes were significantly lower. Cyclopropanation of 1-methyl-1-(trimethylsilyl)allene proceeded in higher yield than other 1,1-disubstituted substrates, suggesting rate enhancement mediated by a significant β-silicon effect.
Eye movements, visual acuity and spatial constancy.

How are eye movements related to acuity or to the lack of spatial constancy, oscillopsia (OSOP)? How do subjects with congenital nystagmus (CN) suppress OSOP? Can we apply their strategies to cases of acquired nystagmus? In normals, the maintenance of target foveation with low retinal slip is thought to be necessary for good visual acuity. Retinal slip velocities below 1.67-4 deg/sec have been given as upper bounds for good vision. Subjects with CN do not usually have OSOP and can have good (even normal) visual acuity. CN subjects can maintain target position (SD = 0.21 deg) and low retinal slip velocities (SD = 1.97 deg/sec). Previously, we identified two possible mechanisms for the suppression of OSOP in subjects with CN : 1) efference copy of the CN waveform to negate the effects of the oscillation or 2) the stable vision available during foveation periods. A 48 year-old man with hereditary CN lost consciousness; when he came to, he had troublesome, intermittent OSOP. Recordings revealed a jerk left with extended foveation (JLef) waveform when OSOP was absent (SD of eye position was 0.24 deg and SD of retinal slip velocity was 1.87 deg/sec). However, with the onset of OSOP, his CN waveform abruptly changed to jerk right (JR) and was biased several degrees to the right of the target. Phase-plane analysis revealed that, during the periods of OSOP, the JR waveform did not enter the foveation window defined by the limits, 0 +/- 0.5 deg and 0 +/- 4.0 deg/sec.(ABSTRACT TRUNCATED AT 250 WORDS)
Equity Capital Flows and Demand for REITs

REITs are attractive to investors due to their unique characteristics such as high dividend yields, low correlation with common stocks, and a potential hedge against inflation. Thus the market demand curve of REIT equities may not be horizontal. This paper examines the shape of the market demand curve for REIT equities by employing REIT equity capital flows as a proxy for REIT aggregate demand. Our results do not support a downward demand curve for REIT equities. That is, we do not find evidence for the price-pressure effect in REIT returns. Instead, we find it is REIT returns that affect REIT equity capital flows rather than REIT equity flows that affect REIT returns. The results are consistent when we allow for the presence of market fundamental variables in our analysis. In addition, a variance decomposition analysis suggests that REIT equity capital flows do not cause revisions in expected cash flows (dividends) that are strong enough to impact REIT returns. Thus our findings are consistent with implications that the market demand curve for REIT equities is horizontal.
Probing the First Stars with Hydrogen and Helium Recombination Emission

Unusual patterns of recombination emission from gas ionized by metal-free stars may distinguish early star-forming galaxies from their present-day counterparts. This pattern arises from the harder ionizing spectrum expected from metal-free stars, which strongly enhances the strength of He II recombination lines. Our calculations indicate that line fluxes of He II λ1640 and λ4686 are sufficiently large to be detected by narrowband and spectroscopic searches for high-redshift emission-line sources at z 5 using current instruments. Beyond z ~ 5, potentially low stellar mass loss and observational limitations may hinder the detectability of Population III stars with this technique. An unknown fraction of Lyα emitters may harbor low-metallicity or metal-free stars. As the predicted He II λ1640 flux is comparable to and may exceed hydrogen Lyα, searches for high-redshift galaxies should consider He II recombination lines as possible identifications for single emission lines in observed spectra. Spectra of metal-free stars may show both H I and He II emission lines, improving the constraints on their redshift and identification. We assess the considerable uncertainties that affect our expectations for the detection and identification of true first-generation stars with present search techniques, including the role of stellar mass loss in spectral evolution and the confusion of ionization by primordial stellar sources and active galactic nuclei in the early universe.
Natural Convection Experiments in a Stratified Liquid-Saturated Porous Medium

Mesure des profils de temperature radiaux et des taux de transfert de chaleur. Modelisation physique et numerique
Plasmas in the earth's magnetotail

An overview of the general characteristics of plasmas within the Earth’s magnetotail and its environs is presented. Present knowledge of the plasmas within these regions as gained via in situ measurements provides the general theme, although observations of magnetic fields, energetic particles and plasma waves are included in the discussion. Primary plasma regimes in the magnetotail are the plasma sheet, its boundary layer, the magnetotail lobes, the boundary layer at the magnetopause and the distant magnetotail. Although great progress in our understanding of these regions is evident in the literature of the past several years, many of their features remain as exciting enigmas to be resolved by future observational and theoretical investigation.
Design and development of a compressible dynamic stall facility

A dynamic stall facility offering a unique new capability for studies of compressibility effects on dynamic stall is described. This facility features complete visual access by mounting the test airfoil between optical-quality glass windows which are rotated in unison to produce the oscillating airfoil motion associated with helicopter rotor dynamic stall. By using the density gradients associated with the rapidly changing dynamic stall flow field, this facility permits simultaneous detailed investigation of the flow on the surface as well as in the flow field surrounding airfoils experiencing dynamic stall.
ESTERIFICATION VIA ACID FLUORIDE ACTIVATION

Abstract The esterification of sterically hindered or non-nucleophilic alcohols may often be problematic. The reaction of alcohols with acid fluorides is reported to be superior to standard acid activation protocols frequently used for difficult esterifications. The acid fluoride methodology was used to produce a hindered linkage between a secondary alcohol (4) and a cyclohexyl amino acid 3, a key intermediate in the formation of a constrained ring didemnin analog.
Catalytic Asymmetric Cycloaddition of Ketenes and Nitroso Compounds: Enantioselective Synthesis of α‐Hydroxycarboxylic Acid Derivatives

The appropriate choice of chiral catalyst and starting materials leads to the synthesis of 1,2-oxazetidin-3-ones by cycloadditions of ketenes with nitroso compounds with very good regioselectivity and enantioselectivity. In addition to serving as potentially bioactive target molecules, the products can be transformed into other important classes of compounds, such as alpha-hydroxycarboxylic acid derivatives.
Hourly profiles of sleep and wakefulness in severely versus mild-moderately demented nursing home patients

The purpose of the current study was to examine differences in hour-by-hour sleep/wakefulness profiles between severely and mild-moderately demented patients, and to assess how many elderly patients remain almost fully asleep or nearly fully awake in each hour of a 24-hour period. Sleep/wakefulness patterns of 67 demented nursing home residents (mean age = 85.7 years) were recorded using Actillume recorders. One 24-hour period was used, and numbers of minutes spent asleep or awake were computed for every hour. There were 46 severely demented patients, and 21 mild-moderately demented patients. The amount of sleep and wakefulness recorded for each hour was compared between the two groups. In addition, the frequencies of patients who remained asleep for more than 90% of each hour, and of those who sustained wakefulness for more than 90% of each hour were computed for every hour, and comparisons were again made between the two groups. Multivariate analysis of variance showed a significant effect of dementia group on the percent of sleep/wakefulness over 24 hours (p = 0.028). Subsequent t-tests performed separately for each hour revealed significant differences between the two dementia groups in 13 out of the 24 hours. Significant differences in the frequencies of patients asleep > 90% or awake > 90% of each hour were centered around the early night and early morning hours. Patients with mild-moderate dementia showed a disproportionate amount of wakefulness during the night, whereas, in addition, patients with severe dementia showed a disproportionate amount of sleepiness during the day. With the progression of dementia, both the capacity to maintain sleep and the capacity to maintain wakefulness are impaired, and result in complete fragmentation of sleep/wakefulness during the night and day.
Computation of recursive programs: theory vs practice

This note is actually an informal exposition of a part of a recent paper by Manna, Ness and Vuillemin. We have two main purposes in this note. First, we present some known results about computation of recursive programs, emphasizing some differences between the theoretical and practical approaches. Second, we introduce the computational induction method for proving properties of recursive programs. It turns out that most known methods for proving properties of programs are very closely related to the computational induction method. We illustrate this point by showing how Floyd's inductive assertions method for proving properties of "flowchart programs" can be expressed in terms of computational induction on recursive programs.
Myometrial thickness according to uterine site, gestational age and prior cesarean delivery

Objective. To evaluate the myometrial thickness (MT) of multiple uterine sites during all three trimesters of pregnancy in an attempt to identify anticipated myometrial thickness in each trimester for these sites.Methods. In this prospective cross sectional study, MT was evaluated by ultrasound in women with viable singleton pregnancies. Women with suspected abruption, accreta, previa, fibroids, uterine and fetal anomalies, abnormal fluid volume, labor were excluded. MT was measured at the fundus, anterior wall (AW), posterior wall (PW), right and left side walls, lower uterine segment (LUS) and under the placenta. The cohort was divided to determine differences in MT at each site in each trimester (TRI). Differences in MT between sites were assessed.Results. One hundred and seventy five women underwent ultrasound by a single observer. There were 25 1st, 100 2nd and 50 3rd TRI scans at mean (SD) gestations of 11.0 (1.9), 21.5 (3.6) and 34.1 (3.0) weeks, respectively. Women were 37% African American, 72% g...
More power to the European Parliament

European parliment Should it have more power? Many observers have expressed scepticism about granting more power to the European Parliament. The sceptics believe that Members of the European Parliament (MEPs) do not vote in a disciplined way and that they vote more often with their country group than with their European Party. Using a unique database consisting of all roll call votes by each individual MEP between 1989 and 1999 (over 6000 votes by over 1000 different MEPs), we show that the sceptics are wrong. Our data shows clearly that MEPs vote more along party lines than along country lines. Party cohesion is comparable to that of the US Congress and is increasing over time whereas country cohesion is low and declining. In short, politics in the European Parliament generally follows the traditional left–right divide that one finds in all European nations. These findings are valid across issues, even on issues like the structural and cohesion funds where one would expect country rather than party cohesion. In votes where the EP has the most power – those held under the so-called co-decision procedure – MEPs participate more and are more party-cohesive. In our opinion, this unique empirical analysis provides grounds for justifying a generalization of the co-decision procedure. — Abdul G.Noury and Gerard Roland
Thiopurine S-Methyltranferase Testing in Idiopathic Pulmonary Fibrosis: A Pharmacogenetic Cost-Effectiveness Analysis

Azathioprine in combination with N-acetylcysteine (NAC) and steroids is a standard therapy for idiopathic pulmonary fibrosis (IPF). Its use, however, is limited by its side effects, principally leukopenia. A genotypic assay, thiopurine S-methyltransferase (TPMT), has been developed that can potentially identify those at risk for developing leukopenia with azathioprine, and thereby limit its toxicity. In those with abnormal TPMT activity, azathioprine can be started at lower dose or an alternate regimen selected. Determine the cost-effectiveness of a treatment strategy using TPMT testing before initiation of azathioprine, NAC, and steroids in IPF by performing a computer-based simulation. We developed a decision analytic model comparing three strategies: azathioprine, NAC and steroids with and without prior TPMT testing, and conservative therapy, consisting of only supportive measures. Prevalence of abnormal TPMT alleles and complication rates of therapy were taken from the literature. We assumed a 12.5% incidence of abnormal TPMT alleles, 4% overall incidence of leukopenia while taking azathioprine, and that azathioprine, NAC, and steroids in combination reduced IPF disease progression by 14% during 12 months. TPMT testing before azathioprine, NAC, and steroids was the most effective and most costly strategy. The marginal cost-effectiveness of the TPMT testing strategy was $49,156 per quality adjusted life year (QALY) gained versus conservative treatment. Compared with azathioprine, NAC and steroids without prior testing, the TPMT testing strategy cost only $29,662 per QALY gained. In sensitivity analyses, when the prevalence of abnormal TPMT alleles was higher than our base case, TPMT was “cost-effective.” At prevalence rates lower than our base case, it was not. TPMT testing before initiating therapy with azathioprine, NAC, and steroids is a cost-effective treatment strategy for IPF.
T. brucei RNA Editing: Adenosine Nucleotides Inversely Affect U-Deletion and U-Insertion Reactions at mRNA Cleavage

In the currently envisioned mechanism of trypanosome mitochondrial RNA editing, U-insertion and U-deletion cycles begin with a common kind of gRNA-directed cleavage. However, natural, altered, and mutationally interconverted editing sites reveal that U-deletional cleavage is inefficient without and activated by ATP and ADP, while U-insertional cleavage shows completely reverse nucleotide effects. The adenosine nucleotides' effects appear to be allosteric and determined solely by sequences immediately adjacent to the anchor duplex. Both U-deletional and U-insertional cleavages are reasonably active at physiological mitochondrial ATP concentration. Notably, ATP and ADP markedly stimulate complete U-deletion and inhibit U-insertion reactions, reflecting their effects on cleavage. These plus previous results suggest that U deletion and U insertion are remarkably distinct.
The Photoelectric and Thermionic Properties of Molybdenum

The variation of the photoelectric sensitivity of a molybdenum surface during prolonged heat treatment has been studied over a period of 300 hours of intense heating. Thin ribbons of molybdenum were heated to a temperature of 1325\ifmmode^\circ\else\textdegree\fi{}C in a high vacuum and the photocurrents produced by the light from a quartz mercury arc were measured with a quadrant electrometer. The photoelectric sensitivity was found to increase as the heating progressed, finally reaching a limiting value. The increase in sensitivity was accompanied by a shift in the wave-length limit from approximately 2600 A. U. to approximately 3800 A. U.The photoelectric work function of molybdenum was determined from the characteristic wave-length limit of the heat treated surface after a condition of stability had been attained. The value of the work function so determined was 3.22\ifmmode\pm\else\textpm\fi{}.16 volts.The thermionic work function of molybdenum was determined for the same speciments. The thermionic emission as a function of temperature was plotted logarithmically according to Richardson's equation. The value of the thermionic work function determined from the slopes of these curves was 3.48\ifmmode\pm\else\textpm\fi{}.07 volts. The photoelectric and thermionic work functions were thus found to agree within 0.26 volts.The variation of photoelectric sensitivity of molybdenum with temperature was observed. The sensitivity was found to increase with temperature, the variation amounting to approximately 30 percent between room temperature and 1000\ifmmode^\circ\else\textdegree\fi{}C.
Generic Diffeomorphisms with Superexponential Growth of Number of Periodic Orbits

Let M be a smooth compact manifold of dimension at least 2 and Diff r (M) be the space of C r smooth diffeomorphisms of M. Associate to each diffeomorphism f;isin; Diff r (M) the sequence P n (f) of the number of isolated periodic points for f of period n. In this paper we exhibit an open set N in the space of diffeomorphisms Diff r (M) such for a Baire generic diffeomorphism f∈N the number of periodic points P n f grows with a period n faster than any following sequence of numbers {a n } n ∈ Z + along a subsequence, i.e. P n (f)>a ni for some n i →∞ with i→∞. In the cases of surface diffeomorphisms, i.e. dim M≡2, an open set N with a supergrowth of the number of periodic points is a Newhouse domain. A proof of the man result is based on the Gontchenko–Shilnikov–Turaev Theorem [GST]. A complete proof of that theorem is also presented.
Catalytic enantioselective direct Michael additions of ketones to alkylidene malonates

Abstract— Enantioselective direct Michael additions of ketones using ( S )-1-(2-pyrrolidinylmethyl)-pyrrolidine as a catalyst aredescribed. Michael adducts with up to 91% e.e. were obtained by the reaction of alkylidene malonates with simple unactivatedketones under mild reaction conditions. © 2001 Elsevier Science Ltd. All rights reserved. An increasing demand for optically active compoundshas stimulated the development of catalytic asymmetricbond-forming reactions. 1 Of the carbon carbon bondforming reactions, the enantioselective Michael reactionhas been one of the most studied in synthetic organicchemistry. 2 Typically, carbon nucleophiles that containan active methylene center such as malonic acid esters, -keto esters, nitroalkanes, etc. have been studied. 3 Ketones, however, while they are versatile carbonnucleophiles, have generally been used as donors onlyfollowing their pre-activation by conversion into highlyreactive enol or enamine equivalents. 4 In these cases,additional synthetic step(s), stoichiometric amounts ofbase, additional reagents (silylating agents to form theenol silyl ether or chiral amines to form the enaminederivative) or chiral ligands are required. A potentiallymore promising strategy would involve catalysis ofdirect additions of unmodiﬁed ketones to Michael-typeacceptors. The development of catalytic asymmetricvariants of this process would provide access to opti-cally enriched 1,5-dicarbonyl synthons.As part of our ongoing program directed towardsidentifying small organic molecules as catalysts ofasymmetric reactions, we explore here the direct addi-tion of ketones through an enamine-type mechanism toMichael-type acceptors. Chiral amines have been usedpreviously in catalytic asymmetric Michael additions,
Spinons in a Crossed-Chains Model of a 2D Spin Liquid

Using the random phase approximation, we show that a crossed-chains model of spin- $1/2$ Heisenberg chains with frustrated interchain couplings has a nondimerized spin-liquid ground state in 2D, with deconfined spinons as the elementary excitations. The results are confirmed by a bosonization study, which shows that the system is an example of a ``sliding Luttinger liquid.'' In an external field, the system develops an incommensurate field-induced long-range order with a finite transition temperature.
R5Pn3-type Phases of the Heavier Trivalent Rare-Earth-Metal Pnictides (Pn=Sb, Bi): New Phase Transitions for Er5Sb3 and Tm5Sb3

The syntheses and distributions of binary R{sub 5}Pn{sub 3} phases among the hexagonal Mn{sub 5}Si{sub 3} (M), and the very similar orthorhombic {beta}-Yb{sub 5}Sb{sub 3} (Y) and Y{sub 5}Bi{sub 3} (YB) structure types have been studied for R = Y, Gd-Lu and Pn = Sb, Bi. Literature reports of M and YB-type structure distributions among R{sub 5}Pn{sub 3} phases, R = Y, Gd-Ho, are generally confirmed. The reported M-type Er{sub 5}Sb{sub 3} could not be reproduced. Alternate stabilization of Y-type structures by interstitials H or F has been disproved for these nominally trivalent metal pnictides. Single crystal structures are reported for (a) the low temperature YB form of Er{sub 5}Sb{sub 3} (Pnma, a = 7.9646(9) {angstrom}, b = 9.176(1) {angstrom}, c = 11.662(1) {angstrom}), (b) the YB- and high temperature Y-types of Tm{sub 5}Sb{sub 3} (both Pnma, a = 7.9262(5), 11.6034(5) {angstrom}, b = 9.1375(6), 9.1077(4) {angstrom}, c = 11.6013(7), 7.9841(4) {angstrom}, respectively), and (c) the YB structure of Lu{sub 5}Sb{sub 3}, a = 7.8847(4) {angstrom}, b = 9.0770(5) {angstrom}, c = 11.5055(6) {angstrom}. Reversible, temperature-driven phase transitions ({beta}-Yb{sub 5}Sb{sub 3} Y{sub 5}Bi{sub 3} types) for the former Er{sub 5}Sb{sub 3} and Tm{sub 5}Sb{sub 3} around 1100 C and themore » means of quenching the high temperature Y form, have been established. According to their magnetic susceptibilities, YB-types of Er{sub 5}Sb{sub 3} and Tm{sub 5}Sb{sub 3} contain trivalent cations. Tight-binding linear muffin-tin-orbital method within the atomic sphere approximation (TB-LMTO-ASA) calculations for the two structures of Tm{sub 5}Sb{sub 3} reveal generally similar electronic structures but with subtle Tm-Tm differences supporting their relative stabilities. The ambient temperature YB-Tm{sub 5}Sb{sub 3} shows a deep pseudogap at EF, approaching that of a closed shell electronic state. Short R-R bonds (3.25-3.29 {angstrom}) contribute markedly to the structural stabilities of both types. The Y-type structure of Tm{sub 5}Sb{sub 3} shows both close structural parallels to, and bonding contrasts with, the nominally isotypic, stuffed Ca{sub 5}Bi{sub 3}D and its analogues. Some contradictions in the literature are discussed.« less
Jones polynomials of torus knots via DAHA

We suggest a construction for the Quantum Groups–Jones polynomials of torus knots in terms of the PBW theorem of double affine Hecke algebra (DAHA) for any root systems and weights (justified for type A). The main focus is on the DAHA super-polynomials, a stable type A variant of this construction. A connection is expected with the approach to super-polynomials due to Aganagic and Shakirov via the Macdonald polynomials at roots of unity and the Verlinde algebra. The duality conjecture for the DAHA super-polynomials is stated, essentially matching that due to Gukov and Stosic. A link to Khovanov–Rozansky polynomials is provided. The hyper-polynomials of types B and C are defined, generalizing the Kauffman polynomials. The special values and other features of the DAHA super- and hyper-polynomials are discussed.
Using neural networks to enhance the Higgs boson signal at hadron colliders.

Neural networks are used to help distinguish the {ital ZZ}{r_arrow}{ital l}{sup +}{ital l}{sup {minus}}-jet-jet signal produced by the decay of a 400 GeV Higgs boson at a proton-proton collider energy of 15 TeV from the {open_quote}{open_quote}ordinary{close_quote}{close_quote} QCD {ital Z}+jets background. The ideal case where only one event at a time enters the detector (no pileup) and the case of multiple interactions per beam crossing (pileup) are examined. In both cases, when used in conjunction with the standard cuts, neural networks provide an additional signal-to-background enhancement. {copyright} {ital 1996 The American Physical Society.}
Social problems of drug use and drug policies.

(1970). Social Problems of Drug Use and Drug Policies. International Journal of the Addictions: Vol. 5, No. 2, pp. 321-333.
The new joint R&D

It is pointed out that the era of collaboration among competitors has arrived. Virtually every vendor of semiconductor devices, equipment, and materials is engaged in at least one multicompany collaboration to develop processes, tools, and technologies. In 1982, when Microelectronics and Computer Technology Corporation (MCC) was founded, the prevailing view was that competitors cannot and should not share proprietary information, that their competitive habits overpower any collaborative desires, and that invention is fundamentally best undertaken by each company on its own. Today, that skepticism must confront the changes that have taken place in the world of industrial and academic research and development. The author provides examples of collaborative work, looks into the logic of joint research and development, and considers the design of R&D collaboratives, their secretariats, their operating entities, and their future. >
Quantum dots in biology and medicine

Semiconductor quantum dots (QDs) are nanometer-sized crystals with unique photochemical and photophysical properties that are not available from either isolated molecules or bulk solids. In comparison with organic dyes and fluorescent proteins, these quantum-confined nanoparticles are brighter, more stable against photobleaching, and can be excited for multicolor emission with a single light source. Recent advances have shown that nanometer-sized semiconductor particles can be covalently linked with biorecognition molecules such as peptides, antibodies, nucleic acids, or small-molecule ligands for use as biological labels. High-quality QDs are also well suited for optical encoding and multiplexing applications due to their broad excitation profiles and narrow/symmetric emission spectra. In this article, we discuss recent developments in QD synthesis and bioconjugation, their applications in molecular and cellular imaging, as well as promising directions for future research.
The effects of currency crises on the long-run growth

We attempt to analyse the effects of the currency crises on the long-run growth by using a cross-sectional country dataset. After controlling for the post-crisis period, we find that the effects of the currency crises on the long-run growth are strictly negative and significant. We also find that the negative effects of the currency crises on the long-run growth increase as the number of the currency crises increases.
The line-of-sight proximity effect and the mass of quasar host halos

We show that the Ly? optical depth statistics in the proximity regions of quasar spectra depend on the mass of the dark matter halos hosting the quasars. This is owing to both the overdensity around the quasars and the associated infall of gas toward them. For a fiducial quasar host halo mass of -->(3.0 ? 1.6) ? 1012 h?1 M?, as inferred by Croom and coworkers from clustering in the 2dF QSO Redshift Survey, we show that estimates of the ionizing background (?bkg) from proximity effect measurements could be biased high by a factor of 2.5 at -->z = 3 owing to neglecting these effects alone. The clustering of galaxies and other AGNs around the proximity effect quasars enhances the local background but is not expected to skew measurements by more than a few percent. Assuming the measurements of ?bkg based on the mean flux decrement in the Ly? forest to be free of bias, we demonstrate how the proximity effect analysis can be inverted to measure the mass of the dark matter halos hosting quasars. In ideal conditions, such a measurement could be made with a precision comparable to the best clustering constraints to date from a modest sample of only about 100 spectra. We discuss observational difficulties, including continuum flux estimation, quasar systematic redshift determination, and quasar variability, which make accurate proximity effect measurements challenging in practice. These are also likely to contribute to the discrepancies between existing proximity effect and flux decrement measurements of ?bkg.
The Influence of Horizontal Boundaries on Ekman Circulation and Angular Momentum Transport in a Cylindrical Annulus

We present numerical simulations of circular Couette flow in axisymmetric and fully three-dimensional geometry of a cylindrical annulus inspired by Princeton magnetorotational instability (MRI) liquid gallium experiment. The incompressible Navier–Stokes equations are solved with the spectral element code Nek5000 incorporating realistic horizontal boundary conditions of differentially rotating rings. We investigate the effect of changing rotation rates (Reynolds number) and of the horizontal boundary conditions on flow structure, Ekman circulation and associated transport of angular momentum through the onset of unsteadiness and three-dimensionality. A mechanism for the explanation of the dependence of the Ekman flows and circulation on horizontal boundary conditions is proposed.
Partial covering arrays and a generalized Erdös-Ko-Rado property

The classical Erdýos-Ko-Rado theorem states that if k ≤ ⌊n/2⌋ then the largest family of pairwise intersecting k-subsets of [n] = {0,1, . . . , n} is of size n 1 k 1
Electronic structure, superconductivity, and substitution patterns in Tl5Te3

Tl5Te3 adopts a common intermetallic structure type (Cr,B), and shows a superconducting transition at 3 K. Based on the structure of Tl5Te3, 20% of the thallium atoms show crystal chemical behavior consistent with Tl2, according to the formulation Tl (Tl)3(Te)3. These Tl atoms are susceptible to disproportionation into Tl1 and Tl1. In order to explore this aspect of the electronic structure of Tl5Te3 and to investigate potential mechanisms for superconductivity, semi-empirical electronic calculations were carried out on this compound. Recent experiments illustrate that Sn, as well as Bi Pb, and Cu, can substitute for one-fifth of the thallium atoms to give SnTT, Te. Both thallium sites are substituted by Sn according to the formula (Sna,b Tla)(Snc,pTlc)Te5. Energy density of states and crystal orbital overlap population curves for observed and hypothetical substitution patterns are examined to assess the electronic stability of these phases and to account for the observed arrangement.
Shape-sensitivity analysis and design optimization of linear, thermoelastic solids

In this study, a numerical scheme is developed for shape-sensitivity analysis and design optimization of linear, quasistatic, thermoelastic solids. In this scheme, the finite-element method is used as the analyzer for analyzing stress, temperature, shape sensitivity, and design velocity field. Based upon the method of material derivatives, both the techniques of the direct-differentiation method and the adjoint-variable method are applied to derive the shape-sensitivity equations. The shape-optimization formulations discussed here include boundary integrals of displacements and heat fluxes as well as domain integrals of stresses and areas. Numerical results show that the proposed scheme works well in terms of accuracy.
Globalization and economic development

A feature of the continuing integration of the world economy is the globalization of production and the consequent rise of trade in parts and components. Products are more internationalized and less identified with any particular country. Non-trivial shares of the value-added of many exports consist of imports and vice versa. Extension of the international division of labour beyond finished products offers developing countries a broader range of choices for industrialization. This paper explores the implications of these developments in the context of a standard trade model. Component specialization in a developing country's import sector is shown to be superior in overall welfare terms to specialization in the integrated product. Output and employment are higher in the sector, but the wage-rental ratio is lower.
Beckmann fragmentation versus Beckmann rearrangement in dehydronorcamphor derivatives

Abstract Attempted Beckmann rearrangement of dehydronorcamphor oxime resulted in Beckmann fragmentation and dimerization of the intermediate cyanomethylcyclopenta-1,3-diene isomers. The dienes can be trapped by N-phenylmaleimide to yield two isomeric crystalline adducts. When the olefin in dehydronorcamphor oxime is effectively blocked, Beckmann rearrangement takes place to provide stereochemically pure bicyclic lactam.
An optimality theory of concurrency control for databases

A concurrency control mechanism (or a scheduler) is the component of a database system that safeguards the consistency of the database in the presence of interleaved accesses and update requests. We formally show that the performance of a scheduler, i.e., the amount of parallelism that it supports, depends explicitly upon the amount of information that is available to the scheduler. We point out that most previous work on concurrency control is simply concerned with specific points of this basic trade-off between performance and information. In fact, several of these approaches are shown to be optimal for the amount of information that they use.
Halogens halt aromatic group migration in Baeyer–Villiger oxidation

Abstract Oxidation of a dihalogenated benzaldehyde under Baeyer–Villiger conditions led to the aromatic carboxylic acid as opposed to the desired phenol. Fluorine was located at the para -position of the benzaldehyde, halting migration of the aryl group and thus resulting in the carboxylic acid product.
Dependence of the superconducting transition temperature of MgB2 on pressure to 20 GPa

Abstract The dependence of Tc on nearly hydrostatic pressure has been measured for an isotopically pure ( 11 B) MgB2 sample in a helium-loaded diamond-anvil-cell to nearly 20 GPa. Tc decreases monotonically with pressure from 39.1 K at ambient pressure to 20.9 K at 19.2 GPa. The initial dependence is the same as that obtained earlier (dTc/dP≃−1.11(2) K/GPa) on the same sample in a He-gas apparatus to 0.7 GPa. The observed pressure dependence Tc(P) to 20 GPa can be readily described in terms of simple lattice stiffening within standard phonon-mediated BCS superconductivity.
The Magnetic Rayleigh-Taylor Instability in Three Dimensions

We study the magnetic Rayleigh-Taylor instability in three dimensions, with focus on the nonlinear structure and evolution that results from different initial field configurations. We study strong fields in the sense that the critical wavelength λc, at which perturbations along the field are stable, is a large fraction of the size of the computational domain. We consider magnetic fields that are initially parallel to the interface, but have a variety of configurations, including uniform everywhere, uniform in the light fluid only, and fields that change direction at the interface. Strong magnetic fields do not suppress instability; in fact, by inhibiting secondary shear instabilities they reduce mixing between the heavy and light fluid and cause the rate of growth of bubbles and fingers to increase in comparison to hydrodynamics. Fields parallel to, but whose direction changes at, the interface produce long, isolated fingers separated by the critical wavelength λc, which may be relevant to the morphology of the optical filaments in the Crab nebula.