cssi/SciSciGPT-SciSciNet huggingface dataset:
Development of a Dynamic Model for Predicting the Rigid and Flexible Motions of the Crank Slider Mechanism

A continuous model is developed to predict the rigid and flexible motions of the piston assembly/connecting rod/crankshaft mechanism for a single cylinder engine. The model accounts for the torsional vibration and the out-of-plane transverse deformation of the crankshaft along with the out-of-plane transverse deformation of the connecting rod. The eigenvalue problem of the crankshaft, including the counterweights, the flywheel, and the crank gear, is solved to obtain the analytical expressions for the elastic modes of the crankshaft. The resulting mode shapes are then used in the assumed modes method to approximate the structural flexibility terms. The differential-algebraic equations of motion are obtained by implementing the Lagrange principle. The digital simulation results illustrate the role played by the topological nonlinearities inherent in the system and reveal the relationships with which the rigid and flexible motions of the crank-slider mechanism would interact.
Application of Density Functional Theory Based Car-Parrinello Simulations to the Study of Catalytic Processes

We review recent applications of density functional theory based Car-Parrinello molecular dynamics simulations to the study of the structure and reactivity of liquid superacids. We first discuss the nature of an excess proton in liquid hydrofluoric acid, which can be considered as the simplest model of a liquid superacid. Then, we analyze the origin of the superacidity of real superacids in two limiting cases, namely in boron triflouride and antimony pentafluoride in hydrofluoric acid solutions, which are one of the weakest and the strongest known superacids, respectively. We conclude by discussing some aspects of the chemical reactivity of carbon monoxide and simple hydrocarbons in SbF5/HF solutions.
Photo Quiz: Diarrhea and Fever in a Child Returning from Africa

A previously healthy 22-month-old African-American female presented with a 5-day history of diarrhea and fever that had begun immediately upon return from a 2.5-month-long stay in Niger. She had been evaluated at an outpatient clinic, where she was found to be dehydrated, so she was given
TIME DEPENDENT RESONANCE THEORY

An important class of resonance problems involves the study of perturbations of systems having embedded eigenvalues in their continuous spectrum. Problems with this mathematical structure arise in the study of many physical systems, e.g. the coupling of an atom or molecule to a photon-radiation field, and Auger states of the helium atom, as well as in spectral geometry and number theory. We present a dynamic (time-dependent) theory of such quantum resonances. The key hypotheses are (i) a resonance condition which holds generically (non-vanishing of the Fermi golden rule) and (ii) local decay estimates for the unperturbed dynamics with initial data consisting of continuum modes associated with an interval containing the embedded eigenvalue of the unperturbed Hamiltonian. No assumption of dilation analyticity of the potential is made. Our method explicitly demonstrates the ow of energy from the resonant discrete mode to continuum modes due to their coupling. The approach is also applicable to nonautonomous linear problems and to nonlinear problems. We derive the time behavior of the resonant states for intermediate and long times. Examples and applications are presented. Among them is a proof of the instability of an embedded eigenvalue at a threshold energy under suitable hypotheses.
Microwave-assisted Expeditious and Efficient Synthesis of Cyclopentene Ring-fused Tetrahydroquinoline Derivatives Using Three-component Povarov Reaction

Abstract We report here an efficient and expeditious microwave-assisted synthesis of cyclopentadiene ring-fused tetrahydroquinolines using the three-component Povarov reaction catalyzed by indium (III) chloride. This method has an advantage of shorter reaction time (10–15 min) with high and reproducible yields (up to 90%) and is suitable for parallel library synthesis. The optimization process is reported and the results from the microwave route are compared with those of the conventional synthetic route. In almost all cases, the microwave acceleration consistently provided improved yields favoring the cis-diastereomer.
Solar Doppler-shift measurements in the Ne VII 465 A emission line

Using a Dopplergram obtained with the Naval Research Laboratory extreme ultraviolet spectrograph on Skylab, we have searched for Doppler shifts in the Ne VII 465 A emission line, which is formed at a temperature of about 500,000 K. In the quiet sun we find no measurable average Doppler shift to a measurement accuracy of +/- 18 km/s. Small regions of the quiet sun do, however, display measurable Doppler shifts. In active regions, we measure Doppler shifts indicating downflow velocities of up to 70 km/s.
Universal back-projection algorithm for photoacoustic computed tomography

We report a universal back-projection formula for three-dimensional photoacoustic computed tomography in three types of imaging geometries: planar, spherical, and cylindrical surfaces. A solid-angle weighting factor is introduced in the back-projection formula to compensate for the variations of detection views. Numerical simulation demonstrates the performance of the algorithm.
The effect of norepinephrine versus epinephrine on regional cerebral blood flow during cardiopulmonary resuscitation.

alpha-Adrenergic drugs improve cerebral blood flow (CBF) during cardiopulmonary resuscitation (CPR), in part, by reversing carotid artery collapse and by shunting blood from extracerebral to intracerebral vascular structures. Adrenergic drugs with beta 2-agonist properties may cause peripheral vasodilation, and thus may be less beneficial in this setting. The purpose of this study was to compare epinephrine (E), an alpha 1,2, beta 1,2-agonist, with norepinephrine (NE), an alpha 1,2, beta 1-agonist, on CBF during CPR. Twenty swine each weighing greater than 15 kg were instrumented for regional CBF measurements using tracer microspheres. Regional CBF was measured during normal sinus rhythm (NSR). Animals were then placed into ventricular fibrillation (VF). After ten minutes of VF, the animals received closed-chest CPR using a mechanical thumper. Regional CBF was measured during CPR. After three minutes of CPR, the animals were allocated to receive either E, 0.20 mg/kg (N = 5); NE, 0.08 mg/kg (N = 5); NE, 0.12 mg/kg (N = 5); or NE, 0.16 mg/kg (N = 5). Regional blood flows were again measured following drug administration. CBFs following drug administration were compared using an analysis of covariance adjusting for baseline differences during CPR. A Newman-Keuls multiple comparison was used to follow-up significant (P less than or equal to .05) differences. Statistical significance was considered at P less than or equal to .05. There was a clinically significant improvement in cerebral cortical flow with NE, 0.12 mg/kg, and NE, 0.16 mg/kg, compared with NE, 0.08 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)
Two-dimensional superstrings and the supersymmetric matrix model

We present evidence that the supersymmetric matrix model of Marinari and Parisi represents the world-line theory of N unstable D-particles in type II superstring theory in two dimensions. This identification suggests that the matrix model gives a holographic description of superstrings in a two-dimensional black hole geometry.
On type II superstrings in less than four dimensions

Abstract We study gauge theories which are associated with classical vacua of perturbative type II string theory that allows for a conformal field theory description. We show that even if we compactify seven spatial dimensions (allowing for one macroscopic dimension to arise non-perturbatively) the Standard Model cannot be obtained from the perturbative sector of type II superstrings. Therefore, the construction of the Standard Model (or extensions thereof) from M theory must involve fields that are non-perturbative from the type II perspective. We also address the case of eight compact dimensions.
Somatic embryogenesis and plant regeneration from immature cotyledons of watermelon.

Cotyledon expiants from immature embryos of five watermelon [Citrullus lanatus (Thunb.)Matsum. & Nakai] genotypes were incubated in the dark for three weeks on a modified MS medium containing B5 vitamins, 2,4-D (10, 20 or 40μM), 0.5 μM of either BA or TDZ, and 7 g·1-1 TC agar. Somatic embryos, some with well developed cotyledons, were observed on cotyledon expiants three to four weeks after transfer to MS medium without PGRs and 16h photoperiod. The best PGR combination for somatic embryogenesis was 10 μM 2,4-D and 0.5 μM TDZ Somatic embryogenesis was greatest (30%) when cotyledon expiants were established from 18-day-old immature embryos. Somatic embryos were germinated on MS medium without PGRs. Plants were transferred to Magenta boxes containing ProMix for three weeks before being transplanted to the field where they formed fertile male and female flowers that produced normal fruit.
EFFICIENT BARRIERS TO TRADE: A SEQUENTIAL TRADE MODEL WITH HETEROGENEOUS AGENTS

Abstract This paper studies the choice of tariffs and other type of consumption taxes and subsidies in a flexible price version of the Prescott [Prescott, Edward C., 1975. Efficiency of the Natural Rate. Journal of Political Economy 83, 1229–1236.] hotels model. It is shown that a country with unstable demand may benefit from a tariff on imports. More surprisingly, the exporting country may also benefit from the tariff. In general, I consider the problem of a world planner who chooses country specific consumption taxes and subsidies. I show that buyers in countries that tend to consume relatively more in the high demand state should be taxed and buyers in countries that tend to consume relatively more in the low demand state should be subsidized.
A Non-Supersymmetric Open String Theory and S-Duality

Abstract A non-supersymmetric ten-dimensional open-string theory is constructed as an orbifold of type I string theory, and as an orientifold of the bosonic type B theory. It is purely bosonic, and cancellation of massless tadpoles requires the gauge group to be SO (32) × SO (32). The spectrum of the theory contains a closed-string tachyon, and open-string tachyons in the ( 32,32 ) multiplet. The D-branes of this theory are analyzed, and it is found that the massless excitations of one of the 1-branes coincide with the world-sheet degrees of freedom of the D = 26 bosonic string theory compactified on the SO(32) lattice. This suggests that the two theories are related by S -duality.
Strategic Service Pricing and Yield Management

The authors investigate pricing strategies based on yield management systems (YMS), such as early discounting, overbooking, and limiting early sales, for capacity-constrained services. They find that YMS work best when price-insensitive customers prefer to buy later than price-sensitive consumers. The authors also identify other conditions favoring the use of YMS.
Social network user lifetime

Online social network (OSN) operators are interested in promoting usage among their users, and try a variety of strategies to encourage use. Some recruit celebrities to their site, some allow third parties to develop applications that run on their sites, and all have features intended to encourage use. As important as usage is, there are few studies into what influences users to be active and to remain online. This article studies the lifetime of OSN users, examining the factors that influence lifetime in two OSNs, Twitter and Buzznet. The major contributions of this work are the study of active lifetime, the features and behaviors that encourage activity, and the comparison of active lifetime to passive lifetime.
Temporal distinguishability of an N -photon state and its characterization by quantum interference

We present a multimode model to describe an arbitrary $N$-photon state with a wide spectral range and some arbitrary temporal distribution. In general, some of the $N$ photons are spread out in time while others may overlap and become indistinguishable. From this model, we find that the temporal (in)distinguishability of photons is related to the exchange symmetry of the multiphoton wave function. We find that simple multiphoton detection scheme gives rise to a more general photon bunching effect with the famous two-photon effect as a special case. We then send this $N$-photon state into a recently discovered multiphoton interference scheme. We calculate the visibility of the multiphoton interference scheme and find that it is related to the temporal distinguishability of the $N$ photons. Maximum visibility of one is achieved for the indistinguishable $N$-photon state whereas the visibility degrades when some of the photons are separated and become distinguishable. Thus we can identify an experimentally measurable quantity that may quantitatively define the degree of indistinguishability of an $N$-photon state. This presents a quantitative demonstration of the complementary principle of quantum interference.
Toyota production system for healthcare organisations: prospects and implementation challenges

The objective of this study is to document the implementation of the Toyota production system (TPS) in a Healthcare Organisation – Heartland Regional Medical Center – undertaken to meet accreditation standards and customer service goals. We record the challenges experienced and elaborate the effectiveness of knowledge-management (KM) procedures during TPS implementation. The study addresses an organisation-wide preparation for implementing TPS and the accreditation standards of the National Joint Commission on the Accreditation of Healthcare Organizations. Our observations are centred on the Quality Management Council which has been involved in carrying out improvements in patient care, service, and hospital administration. The study documents the effectiveness of KM approaches such as cross-functional coordination and subject-matter experts in the implementation of TPS. This is a single site case study, and the challenges observed and remedies pursued while implementing TPS may be specific to the site or...
Flavor mediation delivers natural SUSY

If supersymmetry (SUSY) solves the hierarchy problem, then naturalness considerations coupled with recent LHC bounds require non-trivial superpartner flavor structures. Such “Natural SUSY” models exhibit a large mass hierarchy between scalars of the third and first two generations as well as degeneracy (or alignment) among the first two generations. In this work, we show how this specific beyond the standard model (SM) flavor structure can be tied directly to SM flavor via “Flavor Mediation”. The SM contains an anomaly-free SU(3) flavor symmetry, broken only by Yukawa couplings. By gauging this flavor symmetry in addition to SM gauge symmetries, we can mediate SUSY breaking via (Higgsed) gauge mediation. This automatically delivers a natural SUSY spectrum. Third-generation scalar masses are suppressed due to the dominant breaking of the flavor gauge symmetry in the top direction. More subtly, the first-two-generation scalars remain highly degenerate due to a custodial U(2) symmetry, where the SU(2) factor arises because SU(3) is rank two. This custodial symmetry is broken only at order (m c /m t )2. SUSY gauge coupling unification predictions are preserved, since no new charged matter is introduced, the SM gauge structure is unaltered, and the flavor symmetry treats all matter multiplets equally. Moreover, the uniqueness of the anomaly-free SU(3) flavor group makes possible a number of concrete predictions for the superpartner spectrum.
Predatory lending practices and subprime foreclosures: Distinguishing impacts by loan category

Abstract A recent dramatic rise in subprime foreclosures has led to calls for restrictions against a range of loan features loosely termed “predatory.” Several cities and states have enacted regulations to curb predatory practices, and some advocacy groups endorse action at the federal level. Using data on subprime refinance and purchase mortgages from the Chicago metropolitan area, I examine the impact of long prepayment penalty periods, balloon payments and reduced documentation on the probability of foreclosure. Results suggest that the relationship between these loan features and foreclosure rates is much more complicated than the arguments for restricting their use assume.
Algebraic structure theory of stochastic machines

In the present paper, an algebraic structure theory of stochastic machines is developed which contains both Bacon's theory [1] and Hartmanis' theory for deterministic machines [5] as special cases. Although the present theory is patterned after both theories, it exhibits many interesting features which are here-to-fore unknown. Among other things, it is shown that the basic concepts involved, e.g., partitions with substitution property, partition pairs, state-behavior realizations, are all equivalent to well-known concepts in linear algebra. Section II introduces the model of stochastic machines to be used in subsequent developments. In Section III, various types of realizations and assignments are introduced. The concepts of partitions with substitution property, partition pairs, etc. are introduced in Section III. The last section gives a formulation of a network of concurrently operating QSMs.
Human platelet gel supernatant inactivates opportunistic wound pathogens on skin

Activation of human platelets produces a gel-like substance referred to as platelet rich plasma or platelet gel. Platelet gel is used clinically to promote wound healing; it also exhibits antimicrobial properties that may aid in the healing of infected wounds. The purpose of this study was to quantify the efficacy of human platelet gel against the opportunistic bacterial wound pathogens Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus on skin. These opportunistic pathogens may exhibit extensive antibiotic resistance, necessitating the development of alternative treatment options. The antimicrobial efficacy of platelet gel supernatants was quantified using an in vitro broth dilution assay, an ex vivo inoculated skin assay, and in an in vivo skin decontamination assay. Human platelet gel supernatants were highly bactericidal against A. baumannii and moderately but significantly bactericidal against S. aureus in vitro and in the ex vivo skin model. P. aeruginosa was not inactivated in vitro; a low but significant inactivation level was observed ex vivo. These supernatants were quite effective at inactivating a model organism on skin in vivo. These results suggest application of platelet gel has potential clinical applicability, not only in the acceleration of wound healing, but also against relevant bacteria causing wound infections.
Characterization of liquid phase epitaxial GaAs for blocked-impurity-band far-infrared detectors

GaAs Blocked-Impurity-Band (BIB) photoconductor detectors have the potential to become the most sensitive, low noise detectors in the far-infrared below 45.5 cm{sup -1} (220 {micro}m). We have studied the characteristics of liquid phase epitaxial GaAs films relevant to BIB production, including impurity band formation and the infrared absorption of the active section of the device. Knowledge of the far-infrared absorption spectrum as a function of donor concentration combined with variable temperature Hall effect and resistivity studies leads us to conclude that the optimal concentration for the absorbing layer of a GaAs BIB detector lies between 1 x 10{sup 15} and 6.7 x 10{sup 15} cm{sup -3}. At these concentrations there is significant wavefunction overlap which in turn leads to absorption beyond the 1s ground to 2p bound excited state transition of 35.5 cm{sup -1} (282 {micro}m). There still remains a gap between the upper edge of the donor band and the bottom of the conduction band, a necessity for proper BIB detector operation.
Calculations of neutron transport through a simulated waste matrix

Abstract The assay of nuclear waste characterized as Remote-Handled Transuranic (RH-TRU) waste presents a formidable problem due to the waste's high neutron and γ-ray backgrounds. The differential die-away technique (DDT) that is currently employed as a method for the assay requires the incidence of a large fluence of thermal neutrons within the volume element that contains fissile material. To study the neutron moderation and transport through nuclear waste matrices of different densities, the simulation of neutron transport was initiated using the Monte Carlo N-Particle (MCNP) code. A series of calculations using the MCNP 4A computer code have taken place. The calculations were performed to examine neutron transport across a wide range of waste matrix densities and interrogating neutron source energies. A composite matrix based on elemental analysis of RH-TRU legacy waste at ORNL was simulated and the density of this composite was varied between 200 and 2000 kg/m3. An isotropic interrogating neutron source was varied from 0.01 to 15 MeV to examine the transport of neutrons across these various densities. Fast (0.01–15 MeV), epithermal (10−7–0.01 MeV), and thermal (10−8–10−7 MeV) neutron transport was examined. The moderation of fast neutrons into thermal neutrons and their subsequent transport to the center of the drum was studied. A table with predictions of lower limits of detection of fissile material in a RH-TRU waste drum under certain conditions has been prepared.
Cosmic infrared background and early galaxy evolution

The cosmic infrared background (CIB) reflects the sum total of galactic luminosities integrated over the entire age of the universe. From its measurement the red-shifted starlight and dust-absorbed and re-radiated starlight of the CIB can be used to determine (or constrain) the rates of star formation and metal production as a function of time and deduce information about objects at epochs currently inaccessible to telescopic studies. This review discusses the state of current CIB measurements and the (mostly space-based) instruments with which these measurements have been made, the obstacles (the various foreground emissions) and the physics behind the CIB and its structure. Theoretical discussion of the CIB levels can now be normalized to the standard cosmological model narrowing down theoretical uncertainties. We review the information behind and theoretical modeling of both the mean (isotropic) levels of the CIB and their fluctuations. The CIB is divided into three broad bands: near-IR (NIR), mid-IR (MIR) and far-IR (FIR). For each of the bands we review the main contributors to the CIB flux and the epochs at which the bulk of the flux originates. We also discuss the data on the various quantities relevant for correct interpretation of the CIB levels: the star-formation history, the present-day luminosity function measurements, resolving the various galaxy contributors to the CIB, etc. The integrated light of all galaxies in the deepest NIR galaxy counts to date fails to match the observed mean level of the CIB, probably indicating a significant high-redshift contribution to the CIB. Additionally, Population III stars should have left a strong and measurable signature via their contribution to the CIB anisotropies for a wide range of their formation scenarios, and measuring the excess CIB anisotropies coming from high z would provide direct information on the epoch of the first stars.
A comparative ab initio study of the geometry and force field of thionformic acid with formic and thiolformic acids

Abstract The energy and force field for the planar cis and trans conformers of thionformic acid have been calculated using the 4–31 G basis set, augmented by a complete set of d -functions on the sulfur atom, with full geometry optimization. Extensive comparisons are made between the changes in geometry and selected force constants in going from cis - (chain) to the trans - (ring) structures of thionformic, thiolformic and formic acid. These changes are discussed in terms of a hydrogen bonding type of interaction in the OH⋯S, SH⋯O and OH⋯O structural units respectively. Of the thioacid conformers, the trans -thiol is found to be the most stable; the trans -thion and cis -thiol both about 10 kJ mol −1 less stable; and the cis -thion the least stable by about 38 kJ mol −1 .
Watching Television: Hermeneutics, Reception and Popular Culture

Television - familiarity and phenomenology television - hermeneutics and horizon audiences - constructions of sense viewing and the veridical effect mechanisms of identification in film and television subverting the veridical image towards an "epic" television conclusion - resisting television's familiarity.
Relation of orbital integrals on SO(5) and PGL(2)

We relate the “Fourier” orbital integrals of corresponding spherical functions on thep-adic groups SO(5) and PGL(2). The correspondence is defined by a “lifting” of representations of these groups. This is a local “fundamental lemma” needed to compare the geometric sides of the global Fourier summation formulae (or relative trace formulae) on these two groups. This comparison leads to conclusions about a well known lifting of representations from PGL(2) to PGSp(4). This lifting produces counter examples to the Ramanujan conjecture.
Trade liberalization and compensation

Liberalization harms some groups while generating aggregate benefits. We consider various labor market policies that might be used to compensate those who lose from freer trade. Our goal is to find the policy that compensates each group of losers at the lowest cost to the economy. We argue that wage subsidies should be used to compensate those who bear the adjustment costs triggered by liberalization whereas employment subsidies should be used to compensate those who remain trapped in the previously protected sector. Our analysis indicates that the cost of compensation is low, provided that the right policy is used.
New Iodide Method for Growth of GaN

A new method, Iodine Vapor Phase Growth (IVPG), of growing GaN films and small single crystals by using elemental iodine instead of HCI has been developed. Elemental iodine was used to transport gallium metal into the reaction zone where the gallium iodide reacts with ammonia to produce GaN. GaN films were grown on sapphire substrates having a MOCVD template layer. Films with mobility as high as 660 cm 2 /Vs with carrier concentrations in the range of n = 5 x 10 16 to 3 x 10 17 cm -3 have been grown in a temperature range of 1000 to 1110 °C.
Wilsonian Approach to Fluid/Gravity Duality

The problem of gravitational fluctuations confined inside a finite cutoff at radius r = r c outside the horizon in a general class of black hole geometries is considered. Consistent boundary conditions at both the cutoff surface and the horizon are found and the resulting modes analyzed. For general cutoff r c the dispersion relation is shown at long wavelengths to be that of a linearized Navier-Stokes fluid living on the cutoff surface. A cutoff-dependent line-integral formula for the diffusion constant D (r c ) is derived. The dependence on r c is interpreted as renormalization group (RG) flow in the fluid. Taking the cutoff to infinity in an asymptotically AdS context, the formula for D(∞) reproduces as a special case well-known results derived using AdS/CFT. Taking the cutoff to the horizon, the effective speed of sound goes to infinity, the fluid becomes incompressible and the Navier-Stokes dispersion relation becomes exact. The resulting universal formula for the diffusion constant D(horizon) reproduces old results from the membrane paradigm. Hence the old membrane paradigm results and new AdS/CFT results are related by RG flow. RG flow-invariance of the viscosity to entropy ratio $ \frac{\eta }{s} $ is shown to follow from the first law of thermodynamics together with isentropy of radial evolution in classical gravity. The ratio is expected to run when quantum gravitational corrections are included.
Are supernova kicks responsible for x-ray binary ejection from young clusters?

Recent Chandra observations of interacting and starburst galaxies have led us to investigate the apparent correlation between the positions of young star clusters and the positions of Chandra point sources. Assumed to be X-ray binaries (XRBs), these point sources do not seem to coincide with the massive (~105 M?), young (1-50 Myr) stellar clusters that can easily form systems capable of such emission. We use a sophisticated binary evolution and population synthesis code (StarTrack) and a simplified cluster model to track both the X-ray luminosity and the position of XRBs as a function of time. These binaries are born within the cluster potential with self-consistent positions and velocities, and we show that a large fraction (70%) can be ejected from the parent as a result of supernova explosions and associated systemic velocities. For brighter sources and cluster masses below ~106 M?, we find that the average number of bright XRBs per cluster remains near or below unity, consistent with current observations.
Broadband Self-Noise from a Ducted Fan

This paper describes the prediction of broadband self noise from ducted fans. The source mechanism is assumed to be the interaction of the turbulent boundary layer with the trailing edges of the fan blades. The source levels are obtained from the measurements of self noise from isolated blades by Brooks, Pope and Marcolini and these are corrected to give the in duct sound power from a high solidity fan. It has been found that the blade surface pressures are not uncorrelated on each fan blade and corrections must be included for the scattering from multiple trailing edges. A method is introduced for coupling the modes in a circular duct to the modes of a linear cascade so that the sound power is not singular at the mode cut on frequencies. Results show that the in duct sound power scales with the fifth power of the fan speed at low Mach numbers, but this changes to the sixth power or greater at high Mach numbers. The angle of attack of the blade increases the self noise as 2.4 dB per degree and there are significant increases in low frequency noise when blade stall occurs.
Rhenium(VII) Catalysis of Prins Cyclization Reactions

The rhenium(VII) complex O3ReOSiPh3 is a particularly effective catalyst for Prins cyclizations using aromatic and α,β-unsaturated aldehydes. The reaction conditions are mild, and the highly substituted 4-hydroxytetrahydropyran products are formed stereoselectively. Rhenium(VII) complexes appear to spontaneously form esters with alcohols and to directly activate electron-rich alcohols for solvolysis. Re2O7 and perrhenic acid are equally effective in catalyzing these cyclizations.
Should rates of cataract surgery vary by insurance status

JAMA Variations in Cataract Extraction Rates in Medicare Prepaid and Fee-for-Service Settings Caroline Lubick Goldzweig, MD, MSPH; Brian S. Mittman, PhD; Grace M. Carter, PhD; Tenzing Donyo, MBA; Robert H. Brook, MD, ScD; Paul Lee, MD, JD; Carol M. Mangione, MD, MSPH Objective. —To compare rates of cataract extraction in 2 prepaid health settings and in traditional fee-for-service (FFS) settings. Design. —A cross-sectional analysis using 1993 health maintenance organization (HMO) Medicare claims and encounter files, the Health Care Financing Administration (HCFA) 5% Medicare Part B provider/supplier file, and the HCFA October 1992 100% Medicare population file. Setting. —Southern California Medicare FFS settings and the staff-model and independent practice association (IPA) plans of a large California HMO. Patients. —1993 Medicare beneficiaries aged 65 years and older. The study included 43 387 staff-model HMO enrollees, 19 050 IPA enrollees, and 47 150 FFS beneficiaries (a 5% sample of all Southern California FFS
An experimental study of the effect of private information in the Coase theorem

We investigate, in an experimental setting, the effect of private information on the Coase theorem's predictions of efficiency and allocative neutrality. For a two-person bargaining game, we find significantly more inefficiency and allocative bias in the case of private information compared with the case of complete information. We also find substantial bargaining breakdown, which is not predicted by the Coase theorem. For the case of private information, we reject the Coase theorem in favor of the alternative of a generalized version of the Myerson–Satterthwaite theorem, which predicts inefficiency, allocative bias in the direction of the disagreement point, and some bargaining breakdown.
A New Class of Non-Zeolitic Sorbents for Air Separation: Lithium Ion Exchanged Pillared Clays

Zeolites are the only known sorbents that adsorb N{sub 2} selectively over O{sub 2}, and are used for industrial air separation. Pillared clays (PILCs) have a high Broensted acidity (k.e., high proton density). It is found in this study that when the protons are exchanged by alkali metal ions, in particular Li{sup +}, the ion exchanged pillared clays can exhibit a high N{sub 2}/O{sub 2} adsorption selectivity that rivals that of the zeolites. The first result shows a pure-component adsorption ratio of N{sub 2}/O{sub 2} = 3.2 (at 25 C and 1 atm) for Li{sup +}-exchanged PILC. The N{sub 2} capacity, however, is only 20% that of the zeolite, and remains to be improved. A systematic investigation is conducted on the effects of three factors on the N{sub 2}/O{sub 2} selectivity: (1) starting clays (tetrahedral vs octahedral isomorphous substitution and clays with different charge densities), (2) different metal oxides as pillars, and (3) different ion exchange alkali metal cations (Li{sup +}, Na{sup +}, K{sup +}, Rb{sup +}, and Cs{sup +}). The highest N{sub 2}/O{sub 2} selectivities are achieved by using clays with the highest charge densities, metal oxides forming pillars with the narrowest gallery spaces, and ion exchange cations withmore » the smallest ionic radii. Effects by all three factors are qualitatively understood. The high N{sub 2}/O{sub 2} selectivity on the Li{sup +} exchanged PILC is the result of the small ionic radius (and hence high polarizing power) of Li{sup +} and the strong quadrupole moment of the N{sub 2} molecule. Moreover, a technique is developed with which the amount of the exchanged cations can exceed that allowed by the original cation exchange capacity of the clay by using a high pH value in the ion exchange solution.« less
Linearized gravity in brane backgrounds

A treatment of linearized gravity is given in the Randall-Sundrum background. The graviton propagator is found in terms of the scalar propagator, for which an explicit integral expression is provided. This reduces to the four-dimensional propagator at long distances along the brane, and provides estimates of subleading corrections. Asymptotics of the propagator off the brane yields exponential falloff of gravitational fields due to matter on the brane. This implies that black holes bound to the brane have a ``pancake''-like shape in the extra dimension, and indicates validity of a perturbative treatment off the brane. Some connections with the AdS/CFT correspondence are described.
Cosmological constraints on the scale of supersymmetry breaking

Abstract We consider the cosmological and astrophysical constraints on the decay of massive E 8 × E 8 ′ superstring axions associated with the hidden sector. We find that decay lifetimes greater than 1 s are ruled out by limits from nucleosynthesis, by limits on the distortion of the cosmic microwave and gamma ray backgrounds and by closure arguments. We conclude that Λ > 1.2 × 10 13 GeV, where Λ is the scale of gaugino condensation in the hidden sector. This implies that the scale of supersymmetry breaking is greater than 10 10 GeV. Significantly, our result agrees with the value of 5 x 10 13 GeV for Λ obtained independently by setting supersymmetric scalar masses equal to m w .
q-deformed Fermions

This is a study of q-Fermions resulting from q-deformed algebra of harmonic oscillators arising from two distinct algebras. Employing the first algebra, the Fock states are constructed for the generalized Fermions obeying Pauli exclusion principle. The distribution function and other thermodynamic properties such as the internal energy and entropy are derived. Another generalization of fermions from a different q-deformed algebra is investigated which deals with q-fermions not obeying the exclusion principle. Fock states are constructed for this system. The basic numbers appropriate for this system are determined as a direct consequence of the algebra. We also establish the Jackson Derivative, which is required for the q-calculus needed to describe these generalized Fermions.
Origin of the non-linear pressure effects in perovskite manganites: Buckling of Mn–O–Mn bonds and Jahn–Teller distortion of the MnO6 octahedra induced by pressure

High-pressure resistivity and X-ray diffraction measurements were conducted on La{sub 0.85}MnO{sub 3-{delta}} at 6 and 7 GPa, respectively. At low pressures the metal-insulator transition temperature (TMI) increases linearly up to a critical pressure, P* {approx} 3.4 GPa, followed by reduction in T{sub MI} at higher pressure. Analysis of the bond distances and bond angles reveals that a bandwidth increase drives the increase in T{sub MI} below P*. The reduction in T{sub MI} at higher pressures is found to result from Jahn-Teller distortions of the MnO{sub 6} octahedra. The role of anharmonic interatomic potentials is discussed.
Multiple ion detection: a new tool for neurochemistry and biological psychiatry.

Publisher Summary Multiple ion detection or mass fragmentography is a technology capable of meeting high specificity and sensitivity to measure the small concentrations of putative neurotransmitters, their precursors and metabolites in spinal fluid of man. The technique consists of the use of mass spectrometer for the detection of only certain ions preselected for their m/e values. The mass spectrometer focussed simultaneously upon three fixed nominal mass charge ratios (m/e) provides a sensitive and extremely specific detector for a gas chromatograph. By combining gas chromatography and mass, the chemical identity of a compound can be established and concentration of 10–100 femtomoles per sample can be measured. Multiple ion detection becomes a quantitative method by the addition to the sample of appropriate deuterated internal standards. Knowledge of the mass spectra and of the fragmentation patterns of a compound and of its deuterated analog used as internal standard is necessary to perform the appropriate focusing of the instruments.
Towards content trust of web resources

Trust is an integral part of the Semantic Web architecture. Most prior work on trusts focuses on entity-centered issues such as authentication and reputation and does not take into account the content, i.e., the nature and use of the information being exchanged. This paper defines content trust and discusses it in the context of other trust measures that have been previously studied. We introduce several factors that users consider in deciding whether to trust the content provided by a Web resource. Our goal is to discern which of these factors could be captured in practice with minimal user interaction in order to maximize the quality of the system's trust estimates. We present results on a study to determine which factors were more important to capture, and describe a simulation environment that we have designed to study alternative models of content trust.
Visual aspects of egg care behaviour in Cichlasoma nigrofasciatum (Günther)

Abstract Egg size was found to be an important visual stimulus eliciting egg care behaviour in substrate-spawning Cichlasoma nigrofasciatum. Egg size was manipulated by the use of artificial wax ‘eggs’ while maintaining other visual spects of the spawn unchanged. Egg-care behaviour was compared under two experimental and three control conditions. The experimental conditions consisted of exchanging the eggs for larger or smaller models. The control groups included a baseline record of egg care toward natural eggs, a situation without eggs and one with model ‘eggs’ similar in size to the natural. The results showed that models larger or smaller than real eggs were discriminated; a considerable decrement in several fanning parameters occurred relative to the baseline or natural size model groups. The absence of eggs resulted in the greatest decrement of fanning. These results suggest some hormonal control of egg care behaviour. The length of time spent fanning eggs is a function of the time the eggs are in view; the adaptive significance of this result is discussed.
ACCOUNTING FOR BUSINESS INCOME UNDER INFLATION: CURRENT ISSUES AND VIEWS IN THE UNITED STATES*

To adjust business accounting for inflation, one current proposal is to convert all dollar figures in existing financial statements to units of fixed general purchasing power. A widely offered alternative is to retain the dollar units but replace the historical-cost figures by current values. The two alternatives would yield very different results. After reviewing these and variant proposals, the analysis concentrates on certain major issues: the unit of measurement; the treatment of capital gains; the concept of capital maintenance; and the treatment of changes in the purchasing power of debt. Current value accounting would not correct for changes in the general price level and would involve far more difficult problems of concept and measurement than general purchasing power accounting. The latter is therefore preferable.
Synthesis and reactivity toward acyl chlorides and enones of the new highly functionalized copper reagents RCu(CN)ZnI

Les composes du titre sont prepares par transmetallation a partir d'iodures d'alkyl zinc et du sel CuCN•2LiX. Ils reagissent sur des chlorures d'acyle et des enones pour donner des cetones et des produits d'addition 1,4
Distributional biases in the analysis of climate change

Abstract The economic analysis of global warming is dominated by models based on optimal growth theory. These representative-agent models have an intrinsic distributional bias in favor of the rich. The bias is compounded by the use of ‘revenue-neutrality’ in the allocation of emission permits. The result is mitigation recommendations that are biased downwards.
Anomalous interactions in confined charge-stabilized colloid

Charge-stabilized colloidal spheres dispersed in weak 1:1 electrolytes are supposed to repel each other. Consequently, experimental evidence for anomalous long-ranged like-charged attractions induced by geometric confinement inspired a burst of activity. This has largely subsided because of nagging doubts regarding the experiments' reliability and interpretation. We describe a new class of thermodynamically self-consistent colloidal interaction measurements that confirm the appearance of pairwise attractions among colloidal spheres confined by one or two bounding walls. In addition to supporting previous claims for this as-yet unexplained effect, these measurements also cast new light on its mechanism.
Optimal Rules for Central Bank Interest Rates Subject to Zero Lower Bound

The celebrated Taylor rule provides a simple formula that aims to capture how the central bank interest rate is adjusted as a linear function of inflation and output gap. However, the rule does not take explicitly into account the zero lower bound on the interest rate. Prior studies on interest rate selection subject to the zero lower bound have not produced derivations of explicit formulas. In this work, Taylor-like rules for central bank interest rates bounded below by zero are derived rigorously using a multi-parametric model predictive control framework. This framework is used to derive rules with or without inertia. The proposed approach is illustrated through simulations. Application of the approach to US economy data demonstrates its relevance and provides insight into the objectives underlying central bank interest rate decisions. A number of issues for future study are proposed.
Possible experiment with two counter-orbiting drag-free satellites to obtain a new test of Einstein's general theory of relativity and improved measurements in geodesy

In 1918, J. Lense and H. Thirring calculated that a moon in orbit around a massive rotating planet would experience a nodal dragging effect due to general relativity. We describe an experiment to measure this effect by means of two counter-orbiting drag-free satellites in polar orbit about the earth. For a 2 1/2 year experiment, the measurement should approach an accuracy of 1%. An independent measurement of the geodetic precession of the orbit plane due to the motion about the sun may also be possible to about 10% accuracy. In addition to precision tracking data from existing ground stations, satellite-to-satellite Doppler data are taken at points of passing near the poles to yield an accurate measurement of the separation distance between the two satellites. New geophysical information on both earth harmonics and tidal effects is inherent in this polar ranging data.
Numerical Modelling and Analysis of Peripheral Airway Asymmetry and Ventilation in the Human Adult Lung

We present a new one-dimensional model of gas transport in the human adult lung. The model comprises asymmetrically branching airways, and heterogeneous interregional ventilation. Our model differs from previous models in that we consider the asymmetry in both the conducting and the acinar airways in detail. Another novelty of our model is that we use simple analytical relationships to produce physiologically realistic models of the conducting and acinar airway trees. With this new model, we investigate the effects of airway asymmetry and heterogeneous interregional ventilation on the phase III slope in multibreath washouts. The model predicts the experimental trend of the increase in the phase III slope with breath number in multibreath washout studies for nitrogen, SF(6) and helium. We confirm that asymmetrical branching in the acinus controls the magnitude of the first-breath phase III slope and find that heterogeneous interregional ventilation controls the way in which the slope changes with subsequent breaths. Asymmetry in the conducting airways appears to have little effect on the phase III slope. That the increase in slope appears to be largely controlled by interregional ventilation inhomogeneities should be of interest to those wishing to use multibreath washouts to detect the location of the structural abnormalities within the lung.
Waiting for the invisible hand: Novel products and the role of information in the modern market for food

Abstract This paper places the modern spread of diet-related chronic disease in the United States within the context of more than a century of innovation in food processing technology, discovery in nutrition science, and corrective policy measures aimed at improving public health. We ask whether the current state of affairs represents a market failure, and—if so—what might be done about it. We argue that while today’s industrial food system has its advantages, the asymmetric information problems inherent to this system have resulted in a “lemons-style” breakdown in the market for processed foods. The appropriate policy response to such situations (namely, verifiable quality standards) is well known, but such policies are likely (in the short run) to reduce profits for existing large industrial producers of food. In light of the food industry’s long history of success at regulatory capture, we propose the formation of a new independent food standards agency devoted to protecting the interests of the American consumer.