cssi/SciSciGPT-SciSciNet huggingface dataset:
Eukaryotic translation initiation factor 5A inhibition alters physiopathology and immune responses in a “humanized” transgenic mouse model of type 1 diabetes

Therapeutic options for treatment of type 1 diabetes (T1D) are still missing. New avenues for immune modulation need to be developed. Here we attempted at altering the diabetes outcome of our humanized model of T1D by inhibiting translation-initiation factor eIF5A hypusination in vivo. Double-transgenic (DQ8-GAD65) mice were immunized with adenoviral vectors carrying GAD65 for diabetes induction. Animals were subsequently treated with deoxyhypusine synthase (DHS) inhibitor GC7 and monitored for diabetes development over time. On one hand, helper CD4+ T cells were clearly affected by the downregulation of the eIF5A not just at the pancreas level but overall. On the other hand, the T regulatory cell component of CD4 responded with activation and proliferation significantly higher than in the non-GC7-treated controls. Female mice seemed to be more susceptible to these effects. All together, our results show for the first time that downregulation of eIF5A through inhibition of DHS altered the physiopathology and observed immune outcome of diabetes in an animal model that closely resembles human T1D. Although the development of diabetes could not be abrogated by DHS inhibition, the immunomodulatory capacity of this approach may supplement other interventions directed at increasing regulation of autoreactive T cells in T1D.
Steady thermal convection from a concentrated source in a porous medium

Numerical and approximate analytical solutions are presented for the steady thermal convection in a porous medium resulting from a point source located on the lower boundary of a semi-infinite region. The approximate analytical solution is found to be adequate for Rayleigh numbers greater than 100. Below this value, it is necessary to use numerical techniques to obtain accurate representations of the temperature and flow fields. The results are useful for the preliminary analysis of heat transfer and fluid flow effects due to the implantation of encapsulated nuclear waste material in the seabed. 11 figures.
Local bipartite turán graphs and graph partitioning

Motivated by the NP-hard problem of finding a minimum-weight balanced bipartition of an edge-weighted complete graph, we studied the class of graphs having the same degrees as bipartite Turan graphs. In particular, we established a maximal set of linear equations satisfied by the counts of the possible incidences of 3- and 4-cycles on such graphs. This leads to extremal results that we exploit in a heuristic for the partitioning problem, as well as in the computation of a Lagrangian bound. Preliminary computational results with the heuristic appear to be quite promising. Further results are established linking various adjacency concepts and measures of nonbipartiteness for such graphs. We also demonstrate the potential power of the Lagrangian bound via a family of examples. © 1994 by John Wiley & Sons, Inc.
Efficient Identification of Boosted Semileptonic Top Quarks at the LHC

Top quarks produced in multi-TeV processes will have large Lorentz boosts, and their decay products will be highly collimated. In semileptonic decay modes, this often leads to the merging of the b-jet and the hard lepton according to standard event reconstructions, which can complicate new physics searches. Here we explore ways of efficiently recovering this signal in the muon channel at the LHC. We perform a particle-level study of events with muons produced inside of boosted tops, as well as in generic QCD jets and from W-strahlung off of hard quarks. We characterize the discriminating power of cuts previously explored in the literature, as well two new ones. We find a particularly powerful isolation variable which can potentially reject light QCD jets with hard embedded muons at the 103 level while retaining 80∼90% of the tops. This can also be fruitfully combined with other cuts for O(1) greater discrimination. For W-strahlung, a simple pT-scaled maximum ΔR cut performs comparably to a highly idealized top-mass reconstruction, rejecting an O(1) fraction of the background with percent-scale loss of signal. Using these results, we suggest a set of well-motivated baseline cuts for any physics analysis involving semileptonic top quarks at TeV-scale momenta, using neither b-tagging nor missing energy as discriminators. We demonstrate the utility of our cuts in searching for resonances in the \( t\bar{t} \) invariant mass spectrum. For example, our results suggest that 100 fb−1 of data from a 14 TeV LHC could be used to discover a warped KK gluon up to 4.5 TeV or higher.
Tools for studying aqueous enantioselective lanthanide-catalyzed Mukaiyama aldol reactions

Enantioselective bond-forming reactions catalyzed by chiral lanthanide-based complexes are popular because of their Lewis acidity, solvent compatibility, reusability, and potential to catalyze reactions with high stereospecificity. The stereospecific outcomes of bond-forming reactions catalyzed by asymmetric lanthanide-based precatalysts depend on the coordination chemistry of the precatalysts that can be interrogated with X-ray crystal structures, luminescence measurements, NMR spectroscopy, and computational methods. This review is primarily focused on developments related to lanthanide-based precatalysts since the turn of the century and the techniques used to study coordination environments of lanthanide-based precatalysts for Mukaiyama aldol reactions in aqueous media.
Fragmentation, competition, and limit orders: New evidence from interday spreads

Abstract Daily spreads for NYSE stocks (which also trade off board) with average spreads likely set by the specialist, are found to exhibit spread behavior consistent with the fragmentation hypothesis—volume increases off board widen NYSE spreads. Stocks with average spreads likely dominated by limit orders exhibit a competition effect in 1987, but a fragmentation effect in 1988 and 1989—volume increases off decrease NYSE volume, also widening NYSE spreads. As in previous research, increases in total volume are found to decrease NYSE spreads. These findings lead to the conclusion that multiple markets may be a less effective form of competition than limit orders and that a national system of limit orders (as originally proposed in the National Market System) may further narrow spreads where the specialist's spread is not currently dominated by limit orders.
Solvent and temperature dependence of the fermi resonance parameters in methanol

Abstract The polarized and depolarized Raman spectra of methanol in the CH 3 stretching region (2800–3000 cm −1 ) were measured in the neat liquid as a function of concentration and at various concentrations in the solvents water, dimethyl sulfoxide and carbon tetrachloride. The derived isotropic spectra were fit using the Coupled Oscillator Model to obtain values for the unperturbed peak frequencies and linewidths and the Fermi resonance interaction constant. Trends in the calculated parameters varied significantly in the different solvents, and were interpreted in terms of solution structure. In particular, the results imply that methanol is more basic than water in aqueous mixtures. Derived values of the uncoupled peak frequencies and the interaction constant from the Coupled Oscillator Model were found to be in good agreement with those obtained from the standard perturbation treatment. The former model, however, additionally yields values for the unperturbed linewidths, which are generally narrower than the experimentally measured widths.
Volatility and growth in developing economies: some numerical results and empirical evidence

Abstract This paper analyzes the effect of volatility on growth in a developing economy facing an imperfect world capital market. The analysis comprises: (i) the development of a formal framework for assessing the role of risk on growth; (ii) numerical simulation; and (iii) empirical testing of the model, using data from 61 developing economies. We find that the model plausibly replicates the equilibrium of small stylized economies subject to external and internal sources of risk. We define a benchmark economy and study the effects of various sources of risk and borrowing costs on the equilibrium growth rate, its variability, and welfare. The numerical results obtained are intuitive and supported by empirical evidence.
On the analysis of production data: Practical approaches for hydraulically fractured wells in unconventional reservoirs

Abstract This work presents new solutions to modeling the production performance of hydraulically fractured wells in unconventional reservoirs, where intensive hydraulic fracturing creates a stimulated reservoir volume (SRV) with an induced permeability field within. We found previously that the permeability field induced in the SRV (single porosity) can be effectively represented by an exponential or linear dependence of permeability on the distance measured from the main hydraulic fracture plane. However, many researchers consider dual porosity as a necessary ingredient in modeling unconventional reservoirs. In this work, we extend the induced permeability field model to the dual porosity idealization, considering transient fluid transfer from matrix to natural fractures and distance-dependent properties of the medium of secondary porosity (affected by the intensive stimulation). We show that the combined effect of creating a main fracture and altering the properties of the medium of secondary porosity leads to a production behavior that can be characterized and understood provided that effects related to skin and varying flowing bottomhole pressure are correctly accounted for. In addition to the standard diagnostic tools for decline-curve or rate-transient analysis, we use the ratio between the production time and material balance time, a dimensionless group that enables identifying the characteristic signatures of flow regimes. We provide practical criteria to identify various scenarios affecting the data during the pre-linear and pre-bilinear flow regimes in the reservoir (short times). Then we show that transient, late transient and boundary dominated flow periods can also be diagnosed using the dimensionless group, providing a useful addition to existing procedures involving conventional plots. In connection to the new model, this work also discusses a novel approach to handle non-constant bottomhole pressure, the cause of significant distortion in production data at early times. In particular, we consider the effect of a bottomhole pressure exponentially approaching a stabilized value. We show that the deviation from the idealized constant bottomhole pressure case depends on the flow regime in the reservoir, fluid and reservoir properties, skin factor, and the mean lifetime (the time when 63% of the total change has happened) of the decaying part of the flowing pressure. The results reveal that half-, three-fourths-, and unit-slope straight lines (on log–log plot of production rate versus time) develop at short times during the increasing trend of production rate. These new flow regimes enable to gain useful information about the SRV from the early stage of the production history – if the quality of data allows such a detailed analysis. We present a field example involving multi-fractured horizontal wells producing from a shale-gas reservoir, to illustrate, in a practical manner, how to apply the new approach when interpreting production history of wells in unconventional reservoirs.
The future of obstetrics/gynecology in 2020: a clearer vision. Transformational forces and thriving in the new system

Revamping the delivery of women's health care to meet future demands will require a number of changes. In the first 2 articles of this series, we introduced the reasons for change, suggested the use of the 'Triple Aim' concept to (1) improve the health of a population, (2) enhance the patient experience, and (3) control costs as a guide post for changes, and reviewed the transformational forces of payment and care system reform. In the final article, we discuss the valuable use of information technology and disruptive clinical technologies. The new health care system will require a digital transformation so that there can be increased communication, availability of information, and ongoing assessment of clinical care. This will allow for more cost-effective and individualized treatments as data are securely shared between patients and providers. Scientific advances that radically change clinical practice are coming at an accelerated pace as the underlying technologies of genetics, robotics, artificial intelligence, and molecular biology are translated into tools for diagnosis and treatment. Thriving in the new system not only will require time-honored traits such as leadership and compassion but also will require the obstetrician/gynecologist to become comfortable with technology, care redesign, and quality improvement.
Optimal neuronal tuning for finite stimulus spaces

The efficiency of neuronal encoding in sensory and motor systems has been proposed as a first principle governing response properties within the central nervous system. We present a continuation of a theoretical study presented by Zhang and Sejnowski, where the influence of neuronal tuning properties on encoding accuracy is analyzed using information theory. When a finite stimulus space is considered, we show that the encoding accuracy improves with narrow tuning for one-and two-dimensional stimuli. For three dimensions and higher, there is an optimal tuning width.
A new method for hydroxymethylene peptide isostere synthesis: Asymmetric synthesis of statine

The asymmetric synthesis of (-)-Statine is described. The key step of the synthesis involves the coupling of hemi-acetal 6 with the ketene silyl acetal of methyl acetate.
Confocal fluorescence and Raman microscopy of femtosecond laser-modified fused silica

Modified lines were written inside Corning 7940 fused silica with 130 fs laser pulses from an amplified Ti–sapphire laser operating at 800 nm at a repetition rate of 1 kHz. The sample was scanned at 20 µm s−1 with laser pulse energies ranging from 1 to 35 µJ, resulting in modified lines with diameters ranging from 8 to 40 µm. Confocal fluorescence and Raman microscopy was used to probe for spatial variations in defect concentration and glass structure across the modified lines. The fluorescence intensity decreased with increasing distance from the line centre, whereas the Raman intensity increased. No significant variations in the concentration of three- and four-membered ring structures were observed.
Escape of trapped electrons from a helium surface: a dynamical theory

Abstract We present a dynamical theory which incorporates the electron-electron correlations and the effects of external magnetic fields for an electron escaping from a helium surface. Analytical expressions for the escape rate can be obtained in various limits. In particular, the tunneling rate with a parallel magnetic field is presented explicitly.
Behavioral explanations of efficient public good allocations

Abstract Theorists have studied decentralized allocation mechanisms by characterizing the Cournot-Nash equilibria of the mechanism. However, when a mechanism is operationalized by an iterative decision process, and agents derive utility only from the final outcome, Cournot behavior may not be an appropriate solution concept. We suggest two alternative behavioral models, reservation behavior and satisficing behavior, which recognize the impact of the iterative process upon incentives, yet maintain some of the critical simplifications that have made Cournot behavior an attractive model. We report on nine public good experiments with a Groves-Ledyard general equilibrium mechanism. Overall, the experiments attain highly efficient allocations, despite widespread violations of Cournot behavior. We suggest the explanation that most subjects initially followed reservation behavior, and then came to adopt satisficing behavior.
ASSOCIATED PRODUCTION OF HYPERNUCLEI

Abstract The characteristics of the ( π + ,k + ) reaction, a new experimental tool to produce hypernuclei, are discussed. Results from a recent ( π + , k + ) experiment are presented. Some future prospects of the ( π + , k + ) reaction are discussed.
Neutron capture cross sections from Surrogate measurements

The prospects for determining cross sections for compound-nuclear neutron-capture reactions from Surrogate measurements are investigated. Calculations as well as experimental results are presented that test the Weisskopf-Ewing approximation, which is employed in most analyses of Surrogate data. It is concluded that, in general, one has to go beyond this approximation in order to obtain (n, ) cross sections of su cient accuracy for most astrophysical and nuclear-energy applications. Cross sections for compound-nuclear (n, ) reactions are needed for a variety of applications, including astrophysics and nuclear energy. Modeling astrophysical processes that produce the heavy isotopes beyond iron, simulating nu- clear reactor operations, exploring alternative fuel cycles for energy generation, and studying transmutation options for radioactive waste, requires cross sections for neutron- induced reactions on isotopes from di erent regions of the nuclear chart. As many short-lived species cannot be made into targets for direct cross-section measurements, one has to rely on calculations or explore indirect approaches. The desired accuracies for the cross sections of inter- est, often in the range of 10% or less, can be much smaller than the theoretical uncertainties that exist when the model parameters are insu ciently constrained by data. For in- stance, standard evaluations for the (n, ) reaction on the s-process branch point nucleus 95 Zr (t1=2 = 64 d) vary from each other roughly by a factor of four 1 . Exploiting regional systematics, whenever cross sections or relevant structural data (level densities, -ray strength functions, etc.) for near- by nuclei are known, can provide valuable constraints for the calculations. In this contribution we explore the prospects for de- termining or constraining (n, ) cross sections through Sur- rogate measurements. The Surrogate nuclear reaction tech- nique combines experiment with theory to obtain cross sec- tions for compound-nuclear (CN) reactions, a+A! B ! c+C, involving targets (A) that are di cult or impossible to obtain (1-3). In the Hauser-Feshbach formalism, the cross section for this "desired" reaction takes the form: (Ea) = X
Energetics of Bond Shift in Monohalogen-Substituted Cyclooctatetraenes

Abstract The free energies of activation for bond shift in fluoro-, chloro-, bromo- and iodocyclooctatetraene in THF- d 8 were determined by 13 C NMR spectroscopy to be 12.7, 15.0, 15.4 and 16.1 kcal/mol, respectively, at 298 K. Analysis of HF/6-31G*-optimized geometries and natural atomic charges for the ground state and ring inversion transition state for cyclooctatetraene (COT) and its monofluoro and monochloro derivatives indicates that the bond shift transition state for COT-F is stabilized (relative to COT) by electrostatic interactions between the fluorine and the flanking hydrogens, whereas those of the larger halogens are destabilized by steric interactions with the vicinal CH groups. © 1997 Elsevier Science Ltd.
An SEM examination of granule cell migration in the mouse cerebellum

The inward migration of external granule cells (EGC) from the pial surface of the developing cerebellum to from the (internal) granule cell layer was examined using SEM. Cerebella from male mice ranging in age from days 1–20 were fixed, then fractured through the developing pyramid region. EGC were initially unspecialized cells, forming 2–3 layers at the pial surface. EGC layers increased to 6–8, granule cells in the deeper regions elongated, and a prominent space formed between superficial and deep (premigratory) strata. During peak migration (days 8–12), nests of 4–6 EGC were associated with Bergmann glial fibers (BF) of the Golgi epithelial cells, which crossed molecular and EGC layers to terminate as spiny endfeet at the pial surface. Fibrils of extracellular material (ECM) often linked both premigratory and migrating EGC with a nearby BF. The molecular layer thickened considerably and the parallel fibers were traversed by an increasing number of Bergmann fibers and Purkinje cell processes during this period. As active migration slowed (days 13–20) and EGC reached their destination below the Purkinje cell layer, they lost their polarity and were enmeshed in ECM. The role of the Bergmann fibers and extracellular material in granule cell migration is considered.
Sound velocities of bcc-Fe and Fe0.85Si0.15 alloy at high pressure and temperature

Abstract Studying the velocity–density profiles of iron and iron–silicon alloy at high pressures and temperatures is critical for understanding the Earth’s core as well as the interiors of other planetary bodies. Here we have investigated the compressional wave velocity ( V P ) and density ( ρ ) profiles of polycrystalline bcc-Fe and Fe 0.85 Si 0.15 alloy (8 wt.% Si) using in situ high-energy resolution inelastic X-ray scattering (HERIX) and synchrotron X-ray diffraction spectroscopies in an externally-heated diamond anvil cell (EHDAC) up to 15 GPa and 700 K. Based on the measured velocity–density ( V P – ρ ) and velocity–pressure ( V P – P ) relations of bcc-Fe at simultaneous high pressure and temperature ( P – T ) conditions, our results show a strong V P reduction at elevated temperatures at a constant density. Comparison of the V P – ρ profiles between the bcc-Fe and bcc-Fe 0.85 Si 0.15 alloy indicates that the alloying effect of additional 8 wt.% Si on the V P – ρ relationship of bcc-Fe is predominant via a constant density decrease of approximately 0.6 g/cm 3 (7%). Compared with the literature velocity results for bcc and hcp Fe–Si alloys, the bcc-Fe and Fe–Si alloys exhibit higher V P than their hcp phase counterparts at the given bcc–hcp transition pressures. Our results here strongly support the notion that high temperature has a strong effect on the V P of Fe and that the V P – ρ profile of Fe can be affected by structural and magnetic transitions. Analyses on literature elastic constants of the bcc Fe–Si alloys, as a function of P – T and Si content, show that the bcc phase displays extremely high V P anisotropy of 16–30% and V S splitting anisotropy of 40–90% at high temperatures, while the addition of Si further enhances the anisotropy. Due to the extremely high elastic anisotropy of the bcc Fe–Si alloy, a certain portion of the bcc Fe–Si alloy with the lattice-preferred orientation may produce V P and V S anisotropies to potentially account for the observed seismic anisotropy in the inner core.
Templated biological synthesis of polymers of abiological monomers

A general method for the in vivo incorporation of amino acid analogues into artificial proteins is described. The method involves the construction of an artificial gene encoding the sequence of interest (with the corresponding natural amino acid encoded in place of the analogue), transformation of a bacterial host strain that cannot synthesize the natural amino acid, and induction of protein synthesis in a host culture enriched in the analogue. Results are described for the amino acid analogues selenomethionine, p-fluorophenylalanine, trifluoroleucine and 3-thienylalanine.
Non-Abelian Vortices in Supersymmetric Gauge Field Theory via Direct Methods

Vortices in supersymmetric gauge field theory are important constructs in a basic conceptual phenomenon commonly referred to as the dual Meissner effect which is responsible for color confinement. Based on a direct minimization approach, we present a series of sharp existence and uniqueness theorems for the solutions of some non-Abelian vortex equations governing color-charged multiply distributed flux tubes, which provide an essential mechanism for linear confinement. Over a doubly periodic domain, existence results are obtained under explicitly stated necessary and sufficient conditions that relate the size of the domain, the vortex numbers, and the underlying physical coupling parameters of the models. Over the full plane, existence results are valid for arbitrary vortex numbers and coupling parameters. In all cases, solutions are unique.
Entanglement entropy, planar surfaces, and spectral functions

We consider the universal part of entanglement entropy across a plane in flat space for a QFT, giving a non-perturbative expression in terms of a spectral function. We study the change in entanglement entropy under a deformation by a relevant operator, providing a pertrubative expansion where the terms are correlation functions in the undeformed theory. The entanglement entropy for free massive fermions and scalars easily follows. Finally, we study entanglement entropy across a plane in a background geometry that is a deformation of flat space, finding new universal terms arising from mixing of geometry and couplings of the QFT.
The Armette Test for Evaluating Universal Motor Insulation Systems

The "armette test" was devised to improve the quality of test data and reduce the cost of obtaining it. Test methods to date require the manufacture of an entire motor. Present data can be unduly influenced or even voided should the field change or failure occur during the test. The "armette" is a unit that consists of a simple shaft, laminations, magnet wire, insulation, and varnish. It differs from the standard armature in that it has fewer coils, no commutator, and no fan. When assembled in the test setup it makes use of a built-in fan and slip ring assembly for cooling and electrical connections. The armette test consists of mounting the armette in a fixture, connecting the leads to the slip ring, and starting the cyclic test. The cyclic test contains a stationary heating period, a high-speed spin, an electrical surge test, a coast-to-stop period, and a hypot test. The time for each part of the cycle and the input voltage for the heating period are the controlled variables for the test. The work done and correlations run in developing an armette test are presented. Results obtained indicate that the armette test produces data which correlate with present stall test data.
Gaussian-basis LDA and GGA calculations for alkali-metal equations of state

Recently there has been renewed interest in implementations of density-functional theory for solids using various types of localized basis sets, including atom-centered Gaussian-type functions. While such methods are clearly well adapted to most insulating and semiconducting systems, one might expect them to give a less-than-optimal description of metals relative to plane-wave-type methods. Nevertheless, several successful applications of local-basis methods to metals have recently been reported. Here, we report an application of our Gaussian linear combination of atomic orbitals (LCAO) code to some extremely free-electron-like metals, namely, the alkali metals Li, Na, and K. In agreement with other calculations (both local and plane wave) we find that the local-density approximation (LDA) lattice constants are relatively poor ({approximately}{minus}3{percent} from experiment for the alkali metals versus {plus_minus}1{percent} for many other solids) and that the LDA bulk moduli are {approximately}30{percent} too high. We find that the Perdew-Burke-Enzerhof (PBE) version of the generalized-gradient approximation (GGA) corrects most of this error, in agreement with earlier calculations using similar GGA functionals. The Becke-Lee-Yang-Parr GGA functional gives similar results for the alkali-metal equations of state but is found to overcorrect the errors of the LDA for the cohesive energies, for which the PBE functional is in better agreementmore » with experiment. Our results indicate that the Gaussian-LCAO method should be able to give accurate results for nearly any crystalline solid, since it succeeds even where it would be expected to have the most difficulty. {copyright} {ital 1998} {ital The American Physical Society}« less
A Modified Procedure for the Preparation of Cp2Zr(H)Cl (Schwartz's Reagent)

Abstract A convenient method for the preparation of 65–85 g quantities of Cp2Zr(H)Cl, Schwartz's reagent has been developed. The reagent prepared by this method is of high purity and has several advantages over the reagent prepared by previously reported methods.
Probing higher spin black holes

We study the propagation of scalar fields on various backgrounds in three dimensional higher spin gravity. Our main emphasis is on obtaining the bulk-boundary propagator, which can be efficiently computed using group theory and higher spin gauge symmetry and from which we can extract scalar two-point functions in the dual CFT. As an illustration, we obtain a simple closed form expression for the propagator in a particular spin-3 deformation of AdS3. In the case of higher spin black holes, we prove on general grounds that the propagator respects an imaginary time periodicity consistent with the thermal nature of the black hole; in doing so we make progress in understanding the group exponentiation of the higher spin Lie algebra hs[λ], and its center. We also explicitly compute the propagator in the black hole background at first order in the higher spin charge. Evaluated on the Lorentzian section, the result is consistent with an interpretation in which the black hole has two causally disconnected boundary components, as is the case for the BTZ black hole.
A Fast Algorithm for Simulating the Chordal Schramm-Loewner Evolution

The Schramm–Loewner evolution (SLE) can be simulated by dividing the time interval into N subintervals and approximating the random conformal map of the SLE by the composition of N random, but relatively simple, conformal maps. In the usual implementation the time required to compute a single point on the SLE curve is O(N). We give an algorithm for which the time to compute a single point is O(N p ) with p<1. Simulations with κ=8/3 and κ=6 both give a value of p of approximately 0.4.
Developing a diastereoselective intramolecular [4+3] cycloaddition of nitrogen-stabilized oxyallyl cations derived from N-sulfonyl-substituted allenamides.

Efforts toward achieving a practical and diastereoselective intramolecular [4 + 3] cycloaddition of nitrogen-stabilized oxyallyl cations with tethered dienes are described. Epoxidation of N-sulfonyl substituted allenamides with dimethyldioxirane (DMDO) generates nitrogen-stabilized oxyallyl cations that readily undergo stereoselective [4 + 3] cycloaddition with dienes. Selectivity is found to depend on the tethering length as well as the stability of the oxyallyl cation intermediate, whether generated from N-carbamoyl- or N-sulfonyl-substituted allenamides. The use of chiral N-sulfonyl-substituted allenamides provided minimal diastereoselectivity in the cycloaddition, while high diastereoselectivity can be achieved with a stereocenter present on the tether. These studies provide further support for the synthetic utility of allenamides.
A remark on boundary effects in static vacuum initial data sets

Let (M, g) be an asymptotically flat static vacuum initial data set with non-empty compact boundary ?. We prove that (M, g) is isometric to a spacelike slice of a Schwarzschild spacetime under the mere assumption that ? has zero mean curvature, hence generalizing a classic result of Bunting and Masood-ul-Alam. In the case that ? has constant positive mean curvature and satisfies a stability condition, we derive an upper bound of the ADM mass of (M, g) in terms of the mean curvature and area of ?. Our discussion is motivated by Bartnik's quasi-local mass definition.
Instability and Chaos in Quadruped Gallop

A dynamic model for the two-dimensional quadruped has been developed. The main body is modelled as a rigid bar and each leg consists of a constant stiffness spring, a viscous damper and a force actuator. Based on symmetry principles, a controller has been devised that will enable the quadruped to gallop at constant speed. The controller consists of two parts: an energy controller which will apply the required amount of force through the legs, and the speed controller that will control the forward speed by appropriately placing the legs. It will be shown that the body pitch need not be explicitly controlled. The stability of this controller will be examined using Poincare maps. Stable systems show either periodic or quasi-periodic response. This system also exhibits chaotic behavior and chaotic response results in instability. The stability of the system with changes in the initial conditions, as well as variations in the system parameters, will also be examined. It will be shown that the system is stable for a range of leg stiffnesses. Outside this range, the system shows chaotic behavior.
Stereoregular Polymerization of Butadiene with Alkylaluminum Chlorides and Cobalt Octoate

Abstract The requirement of water or oxygen to activate the diethylaluminum chloride co-catalyst used with a cobalt compound to produce 98 per cent cis-1,4 poly-butadiene was reported previously. Activation is considered to form two alkylaluminum compounds differing in Lewis acidity. Several reactions presumed to lead to the formation of the higher acid were carried out with a minor proportion of the diethylaluminum chloride by partial dealkylation with organic hydroperoxide, halogen, tertiary alcohol, organic halide or aluminum. Water is neither necessary nor desirable in the ethylaluminum sesquichloride-cobalt octoate catalyst system. Polar solvents do not appreciably alter the cis-1,4 catalysis with diethylaluminum chloride/water/cobalt octoate, but do decrease the rate or extent of polymerization with increasing dielectric constant of the solvent. A mechanism of cobalt catalysis of butadiene polymerization is proposed.
Determination of Nucleosynthetic Yields of Supernovae and Very Massive Stars from Abundances in Metal-Poor Stars

We determine the yields of the elements from Na to Ni for Type II supernovae (SNe II) and the yield patterns of the same elements for Type Ia supernovae (SNe Ia) and very massive (≳100 M_☉) stars (VMSs) using a phenomenological model of stellar nucleosynthesis and the data on a number of stars with -4 ≾[Fe/H]≾-3, a single star with [Fe/H] = -2.04, and the Sun. We consider that there are two distinct kinds of SNe II: the high-frequency SNe II(H) and the low-frequency SNe II(L). We also consider that VMSs were the dominant first-generation stars formed from big bang debris. The yield patterns of Na to Ni for SNe II(H), II(L), and Ia and VMSs appear to be well defined. It is found that SNe II(H) produce almost none of these elements; that SNe II(L) can account for the entire solar inventory of Na, Mg, Si, Ca, Ti, and V; and that compared with SNe II(L), VMSs underproduce Na, Al, V, Cr, and Mn, overproduce Co, but otherwise have an almost identical yield pattern. A comparison is made between the yield patterns determined here from the observational data and those calculated from ab initio models of nucleosynthesis in SNe II and VMSs. We show that the evolution of the "heavy" elements in the universe relative to Fe involves three distinct stages. The earliest stage is in the domain of [Fe/H] -1 is then governed by contributions from SNe II(H), II(L), and Ia and low-mass stars. It is shown that the abundances of non-neutron capture elements in stars with [Fe/H] ≤ 0 and those of r-process elements in stars with [Fe/H] < -1 can be well represented by the sum of the distinct components in the phenomenological model. The proposed evolutionary sequence is directly related to the problems of early aggregation and dispersion of baryonic matter and to the onset of formation and chemical evolution of galaxies. It is argued that the prompt inventory governed by VMS contributions should represent the typical composition of dispersed baryonic matter in the universe, and that normal galactic evolution should begin in matter with [Fe/H] ≈ 3.
Two computational regimes of a single-compartment neuron separated by a planar boundary in conductance space

Recent in vitro data show that neurons respond to input variance with varying sensitivities. Here we demonstrate that Hodgkin-Huxley (HH) neurons can operate in two computational regimes: one that is more sensitive to input variance (differentiating) and one that is less sensitive (integrating). A boundary plane in the 3D conductance space separates these two regimes. For a reduced HH model, this plane can be derived analytically from the V nullcline, thus suggesting a means of relating biophysical parameters to neural computation by analyzing the neuron's dynamical system.
Mild and General Palladium-Catalyzed Synthesis of Methyl Aryl Ethers Enabled by the Use of a Palladacycle Precatalyst

A general method for the Pd-catalyzed coupling of methanol with (hetero)aryl halides is described. The reactions proceed under mild conditions with a wide range of aryl and heteroaryl halides to give methyl aryl ethers in high yield.
Nonmalignant Renal Disease in Pediatric Patients With Beckwith-Wiedemann Syndrome

OBJECTTVE. The objective of this retrospective review was to determine the incidence and spectrum of nonmalignant renal disease in patients with Beckwith-Wiedemann syndrome. MATERIALS AND METHODS. Patient records were obtained from the Beckwith-Wiedemann Registry of the National Cancer Institute. Imaging findings and medical records of 152 neonates, infants, children, and adults with Beckwith-Wiedemann syndrome (age range, 1 day to 30 years old; median age, 1 year 3 months old) were retrospectively reviewed by three radiologists. Available pathologic material also was reviewed. RESULTS. Thirty-eight (25%) of 152 patients with Beckwith-Wiedemann syndrome had 45 nonmalignant renal abnormalities, including medullary renal cysts (n = 19, 13%), caliceal diverticula (n = 2, l%), hydronephrosis (n = 18, 12%), and nephrolithiasis tn = 6,4%). Thirty-three (8’7%) of the 38 patients with nonmalignant renal disease were asymptomatic. Clinical manifestations of the remaining five patients, included unnary tract infections (n = 4) and flank pain due to obstructive stone disease (n = 1). Nonmalignant renal disease was mistaken for Wilms’ tumor and nonmalignant renal disease. CONCLUSION. Nonmalignant renal abnormalities occur in approximately 25% of patients with Beckwith-Wiedemann syndrome but are generally asymptomatic. Nonmalignant renal abnormalities should be considered in the differential diagnosis of a mass revealed during screening sonography of a patient with Beckwith-Wiedemann syndrome to avoid unnecessary surgery. Editorial Comment: The authors reviewed the patient records of the Beckwith-Wiedemann registry at the National Cancer Institute. The records included 152 patients 1 to 30 years old (median age 1 year 3 months). Of these patients 38 (25%) actually had 45 nonmalignant renal processes, including medullary cysts (19), caliceal diverticula (2), hydronephrosis (18) and nephrolithiasis (6). Of these patients 33 (87%) were asymptomatic when the abnormality was discovered and the remainder had varying symptoms, including urinary tract infection in 4 and flank pain due to obstructive stone disease in 1. In 2 of these patients nepktomy was performed for suspected Wilms tumor when in fact the patients had nonmalignant renal disease. The most important message in this study is the recognition that not all renal pathology in patients with the Beckwith-Wiedemann syndrome is secondary to Wilms tumors, and that adequate evaluation clinically and radiographically is important before surgery is performed.
Some problems of the thin-film cadmium-sulfide solar cell

Studies were made of the degradation of 50 cm2cadmium-sulfide thin-film solar cells caused by exposure to humidity and simulated space environment. Uncovered cells and those laminated with Capran adhesive were degraded at rates proportional to the amount of moisture present. Cells that lost less than 50 percent of their original output could be restored completely by being heated in a vacuum. Recent cells laminated with epoxy adhesive are not affected by moisture. Cadmium-sulfide solar cells fabricated with metal substrates and electroplated gold grids or with plastic substrates have very long thermal cycling lives in simulated space environments.
Sedimentation of two arbitrarily oriented spheroids in a viscous fluid

Abstract The translational and rotational motions of two prolate spheroids sedimenting in a viscous fluid have been determined by the method of reflections. No restrictions are imposed on the spheroid orientations or relative sizes. As is the case in many mobility problems, the method converged rapidly for all but almost touching configurations. The results extend earlier work on special cases such as Wakiya's work on horizontal orientations and agree with Gluckman et al. and Liao and Krueger's boundary collocation solution of axisymmetric problems. Analysis of sedimentation with inclined axes and mirror symmetric geometry reveal both periodic and single-encounter particle trajectories. The calculation of the separatrix between the two behaviors required the use of the higher reflections introduced in this work.
Optimal management of strategic reserves of nonrenewable natural resources

Abstract This paper studies the stockpiling issue for an oil importing country that is likely to suffer embargoes, the occurrence and duration of which are uncertain. I show the existence of a decreasing reserves path that the country wants to attain in order to hedge against these disruptions. Allowing the importing country to invest in R&D in order to free itself from the embargo threat, I determine the optimal effort that should be engaged in research. The incentive to develop a backstop is shown to increase with the depletion of the reserves.
Two components of dark matter in the DAMA data

It is shown that the DAMA data indicate two dark matter components, one that circulates around the galactic center (GC) and another that is emitted from the GC. From the location of the maximum yearly variation, one can compute the ratio of the two components.
Composite laminate optimization program suitable for microcomputers

Abstract The design of a composite panel requires some way of finding the minimum thickness laminate which will withstand the load requirements without failure. The mathematical complexity of this problem dictates the use of nonlinear optimization techniques. Although there are sophisticated optimization programs available capable of solving for the ply ratios, these programs are not often used in preliminary design because they require a large computer and some knowledge of the program's operation. As an alternative, specialized laminate optimization programs were developed which are compact and efficient enough to run on microcomputers. Only stresses at a point and inplane loads and deflections are considered. The programs are simple to use and require no knowledge of optimization. Techniques are developed in this paper that find minimum thickness laminates with either ply ratios or ply angles as design variables. Many test cases were run with these programs to demonstrate the weight savings possible over quasi-isotropic laminates. Particular interest is directed toward performance of the laminates under multiple independent loads. Initial orientations for the programs to operate on were studied, and 0/90/45/-45 laminates were found to be an effective starting point for design.
Fluxbranes in String Theory

A flux p-brane in D dimensions has (p+1)-dimensional Poincare invariance and a nonzero rank (D-p-1) field strength tangent to the transverse dimensions. We find a family of such solutions in string theory and M-theory and investigate their properties.
Imaging the microstructure of menisci using optical coherence tomography

Using optical coherence tomography, changes in the polarization sensitivity of pig menisci were detected both in healthy and enzymatically degraded samples.
The synthesis of dithiolene dyes with strong Near-IR absorption

Cet article presente une serie de composes aromatiques et leurs complexes avec le nickel. Spectres electroniques dans l'infrarouge proche. Synthese bibliographique
Dusty Acoustic Turbulence in the Nuclear Disks of Two LINER Galaxies NGC 4450 and NGC 4736

The structure of dust spirals in the nuclei of the SAab-type LINER galaxies NGC 4450 and NGC 4736 is studied using archival Hubble Space Telescope Planetary Camera images. The spirals are typically only several hundredths of a magnitude fainter than the neighboring disks, so unsharp-mask techniques are used to highlight them. The ambient extinction is estimated to be less than 0.1 mag from the intensity decrements of the dust features and from the spiral surface filling factor, which is about constant for all radii and sizes. The nuclear dust spirals differ from main disk spirals in several respects: the nuclear spirals have no associated star formation, they are very irregular with both trailing and leading components that often cross, they become darker as they approach the center, they completely fill the inner disks with a constant areal density, making the number of distinct spirals (the azimuthal wavenumber m) increase linearly with radius, and their number decreases with increasing arm width as a power law. Fourier transform power spectra of the spirals, taken in the azimuthal direction, show a power-law behavior with a slope of -5/3 over the range of frequencies where the power stands above the pixel noise. This is the same slope as that found for the one-dimensional power spectra of H I emission in the Large Magellanic Cloud and also the slope expected for a thin turbulent disk. All of these properties suggest that the dust spirals are a manifestation of acoustic turbulence in the inner gas disks of these galaxies. Such turbulence should dissipate orbital energy and transfer angular momentum outward, leading to a steady accretion of gas toward the nucleus.
Synthesis of Silver and Copper Nanoparticles in a Water-in-Supercritical-Carbon Dioxide Microemulsion

Nanometer-sized silver and copper metal particles can be synthesized by chemical reduction of Ag+ and Cu2+ ions dissolved in the water core of a water in supercritical fluid carbon dioxide microemulsion. Sodium cyanoborohydride and N,N,N‘,N‘-tetramethyl-p-phenylenediamine are effective reducing agents for synthesizing these metal nanoparticles in the microemulsion. Formation of the metal nanoparticles was monitored spectroscopically using a high-pressure fiber-optic reactor equipped with a CCD array UV−vis spectrometer. Silver and copper nanoparticles synthesized in the microemulsion showed characteristic surface plasmon resonance absorption bands centered at 400 and 557 nm, respectively. Diffusion and distribution of the oxidized form of the reducing agent between the micellar core and supercritical CO2 appeared to be the rate-determining step for the formation of the silver nanoparticles in this system.
Testing for Heterogeneous Parameters in Least-Squares Approximations

This paper suggests tests for the heterogeneity of parameters in linear least-squares estimation. The tests are based on the properties of resampled estimates, and test the hypotheses that the parameters have a common mean, or that they are independently and identically distributed. The tests can be viewed as the analogue of those based on recursive residuals, in cross-sectional models. We analyse the properties of tests based on jack-knifed estimates in the linear regression model, and compare their performance in a small empirical application.