cssi/SciSciGPT-SciSciNet huggingface dataset:
Space charge dynamics of bright electron beams

The longitudinal dynamics and its coupling with the transverse dynamics of bunched beams with strong space charge are analyzed. We introduce a self-consistent Vlasov description for the longitudinal phase space similar to the familiar description for the transverse phase space using a Kapchinskij-Vladimirskij (K-V) distribution [1]. A longitudinal beam envelope equation is derived. An exact solution is then obtained when coupling to the transverse dynamics is ignored. This longitudinal envelope equation is coupled to the transverse envelope equation to form a set of coupled dynamical equations, which is then solved numerically. This analysis is prompted by the surprising results of recent experiments which showed that by driving an intense laser pulse into matter, which in turn creates a plasma, short bright relativistic electron bunches are produced, surprisingly narrowly focused. We find that because the space charge forces weaken with increasing transverse and longitudinal phase space, both the transverse and longitudinal emittance blowout anticipated of bright compact bunches are mitigated by this coupling. It should be possible to capture these bunches into an RF cavity to accelerate to higher energies.
The Strange Allure of State “Right-to-Try” Laws

State right-to-try laws revive a decades-long debate about balancing early access to unapproved medications for terminally ill patients with requirements for demonstrated safety and effectiveness. Although the legal approach is novel, there are many reasons to believe that the laws are likely to be futile. The laws also raise questions about the roles of the state and federal governments in overseeing drugs and medical devices.
Dominantly Fluviatile Origin Under Seasonal Rainfall of the Old Red Sandstone.

Introduction The Devonian system is represented in the British Isles, except in the extreme south of England, by a thick series of red sandstones, shales, and conglomerates. Red sandstone is the predominate outcropping rock, the colors of which range from light red to deep chocolate brown, but in places exhibit green, yellow, gray, and mottled tints. The series of formations which make up this system have been known collectively since the early days of geologic science as the Old Bed Sandstones. In Cornwall and southern Devon the Devonian is represented by slates, grits, volcanic materials, and thick masses of limestone holding marine fossils; but in Ireland, Wales, Scotland, and the contiguous parts of England the formations of equivalent age constitute the totally different facies, the Old Red Sandstones. These show their contrast not only in lithologic character, but in their barrenness of marine fossils. The Devonian age of these rocks . . .
Aggregation of Partial Rankings, p -Ratings and Top- m Lists

We study the problem of aggregating partial rankings. This problem is motivated by applications such as meta-searching and information retrieval, search engine spam fighting, e-commerce, learning from experts, analysis of population preference sampling, committee decision making and more. We improve recent constant factor approximation algorithms for aggregation of full rankings and generalize them to partial rankings. Our algorithms improve constant factor approximation with respect to a family of metrics recently proposed in the context of comparing partial rankings. We pay special attention to two important types of partial rankings: the well-known top-m lists and the more general p-ratings which we define. We provide first evidence for hardness of aggregating them for constant m, p.
Coupling Transcriptional State to Large-Scale Repeat Expansions in Yeast

Summary Expansions of simple DNA repeats cause numerous hereditary disorders in humans. Replication, repair, and transcription are implicated in the expansion process, but their relative contributions are yet to be distinguished. To separate the roles of replication and transcription in the expansion of Friedreich's ataxia (GAA) n repeats, we designed two yeast genetic systems that utilize a galactose-inducible GAL1 promoter but contain these repeats in either the transcribed or nontranscribed region of a selectable cassette. We found that large-scale repeat expansions can occur in the lack of transcription. Induction of transcription strongly elevated the rate of expansions in both systems, indicating that active transcriptional state rather than transcription through the repeat per se affects this process. Furthermore, replication defects increased the rate of repeat expansions irrespective of transcriptional state. We present a model in which transcriptional state, linked to the nucleosomal density of a region, acts as a modulator of large-scale repeat expansions.
A determination of the QED coupling at the Z pole

Abstract We critically examine the evaluation of the hadronic contribution to the running of the QED coupling, α, from Q 2 = 0 to Q 2 = M z 2 . Using data for e + e − → hadrons we find that α ( M z 2 ) −1 = 128.99 ± 706, as compared to the existing value of 128.87 ± 0.12.
Layering and double-diffusion style convection in Europa's ocean

Abstract We assess the effects of fluid composition and depth-dependent hydrostatic pressure on dynamics in a europan ocean primarily composed of aqueous Na 2 SO 4 and MgSO 4 , for both a saturated and a dilute ocean. We observe a salinity- and pressure-dependent check on buoyancy in putative upwellings, which could act as a mechanism for storing heat in the ocean's base. Uptake of salt to a warmed parcel of water from the seafloor environment causes upwellings to lose buoyancy before reaching the base of the overlying ice, implying a tendency toward ocean stratification. We make an analogy to double-diffusive convecting systems observed in the Red Sea and elsewhere in Earth's waters. Using currently understood parameterizations for onset and stability, we estimate a range of temperatures and salinities for which double-diffusive convection may occur in Europa's ocean. In the Red Sea, boundary layers separating convecting zones have been observed to move upward as the lower layer acquires heat and salt. We examine the possibility of stratification and double-diffusive convection as mechanisms for heat storage in Europa's ocean, and possible correlation with recently inferred changes in ice surface alteration style over the last 30–80 Myr.
Dipolar-controlled spin tunneling and relaxation in molecular magnets

Spin tunneling in molecular magnets controlled by dipole-dipole interactions (DDI) in the disordered state has been considered numerically on the basis of the microscopic model using the quantum mean-field approximation. In the actual case of a strong DDI, coherence of spin tunneling is completely lost and there is a slow relaxation of magnetization, described by t 3/4 at short times. Fast precessing nuclear spins, included in the model microscopically, only moderately speed up the relaxation.
X-ray and optical profiler analysis of electroformed X-ray optics

Electroformed grazing incidence mirrors were tested with X-rays and were measured with an optical profiler. Their total effective areas are greater than about 70 percent of the theoretical values both for 1.5- and 6.4-keV X-rays. The half-power diameters are less than about 2 min of arc at 1.5 keV. A design of the mirror array telescope for high energies which has a total effective area of about 1000 sq cm for 7-keV X-rays is presented.
Ln2Al3Si2 (Ln = Ho, Er, Tm): New silicides from molten aluminum - Determination of the Al/Si distribution with neutron crystallography and metamagnetic transitions

Highly metallic compounds with a quasi-one-dimensional structure, the new ternary compounds Ln2 Al3 Si2 (Ln=Ho, Er, Tm) are synthesized in molten aluminum from lanthanoid and silicon as reagents. Their structures show a formally [Al3 Si2 ]6- framework that contains infinite Al zigzag chains and Si-Si dimers and accommodates rows of Ln3+ ions in parallel tunnels. The compounds exhibit metamagnetic transitions at high magnetic fields.
Unitarity of Deconstructed Five-Dimensional Yang-Mills Theory

Abstract The low-energy properties of a compactified five-dimensional gauge theory can be reproduced in a four-dimensional theory with a replicated gauge group and an appropriate gauge symmetry breaking pattern. The lightest vector bosons in these “deconstructed” or “remodeled” theories have masses and couplings approximately equal to those of the Kaluza–Klein tower of massive vector states present in a compactified higher-dimensional gauge theory. We analyze the unitarity of low-energy scattering of the massive vector bosons in a deconstructed theory, and examine the relationship between the scale of unitarity violation and the scale of the underlying chiral symmetry breaking dynamics which breaks the replicated gauge groups. As in the case of compactified five-dimensional gauge theories, low-energy unitarity is ensured through an interlacing cancellation among contributions from the tower of massive vector bosons. We show that the behavior of these scattering amplitudes is manifest without such intricate cancellations in the scattering of the would-be Goldstone bosons of the deconstructed theory. Unlike compactified five-dimensional gauge theories, the amplitude for longitudinal vector boson scattering in deconstructed theories does grow with energy, though this effect is suppressed by 1/(N+1), with N+1 being the number of replicated gauge groups.
Solving the 2-Disjoint Paths Problem in Nearly Linear Time

Given four distinct vertices s1,s2,t1, and t2 of a graph G, the 2-disjoint paths problem is to determine two disjoint paths, p1 from s1 to t1 and p2 from s2 to t2, if such paths exist. Disjoint can mean vertex- or edge-disjoint. Both, the edge- and the vertex-disjoint version of the problem, are NP-hard in the case of directed graphs. For undirected graphs, we show that the O(mn)-time algorithm of Shiloach can be modified to solve the 2-vertex-disjoint paths problem in only O(n + mα(m,n)) time, where m is the number of edges in G, n is the number of vertices in G, and where α denotes the inverse of the Ackermann function. Our result also improves the running time for the 2-edge-disjoint paths problem on undirected graphs as well as the running times for the 2-vertex- and the 2-edge-disjoint paths problem on dags.
Properties of nonlocal charges in the supersymmetric two boson hierarchy

Abstract We obtain the conserved, nonlocal charges for the supersymmetric two boson hierarchy from fractional powers of its Lax operator. We show that these changes reduce to the ones of the supersymmetric KdV system under appropriate reduction. We study the algebra of the nonlocal, local and supersymmetry charges with respect to the first and the second Hamiltonian structures of the system and discuss how they close as a graded nonlinear cubic algebra.
MBE-4, a Heavy Ion Multiple-Beam Experiment

MBE-4, a heavy-ion multiple beam induction linac being built at LBL in FY85/86, will model many features of a much longer device. It will accelerate four spacecharge-dominated Cesium ion beams from, for example, 0.2 MeV, 5 mA/beam, 3.0 ?sec, 1.6 m length at injection to ~0.8 MeV, 15 mA/beam, 1.0 ?sec, 1.1 m length at the exit. It will permit study of simultaneous focussing, acceleration, current amplification and emittance growth of multiple space-charge-dominated ion beams. Some features of this accelerator are described.
Magnetic order and heavy fermion behavior in CePd1+xAl6―x: Synthesis, structure, and physical properties

The physical properties including magnetic susceptibility, specific heat, and electrical resistivity of single crystals are reported for the compound CePd{sub 1+x}Al{sub 6-x} (x=0.5) which crystallizes in the tetragonal SrAu{sub 2}Ga{sub 5}-type structure (space group P4/mmm). The compound was grown from an excess of molten Al flux from the respective elements and the crystal structure was established from single-crystal X-ray diffraction. Anomalies in the low temperature specific heat C{sub p}(T) and electrical resistivity rho(T) show that the compound undergoes ferromagnetic order at T{sub C}=2.8 K. In the ordered state, CePd{sub 1.5}Al{sub 5.5} displays heavy fermion behavior with a Sommerfeld coefficient of ca. 500 mJ/mol-K{sup 2}. - Graphical abstract: The compound CePd{sub 1+x}Al{sub 6-x} (x=0.5) has been synthesized and structurally characterized by single-crystal X-ray diffraction. The measured physical properties of temperature and field dependent magnetic susceptibility, specific heat, and electrical resistivity suggests that the compound undergoes ferromagnetic order at ca. 2.8 K and further exhibits relatively heavy fermion behavior with a Sommerfeld coefficient of 500 mJ/mol-K2.
Weibull Analysis Applied to the Pull Adhesion Test and Fracture of a Metal-Ceramic Interface

Various tests have been developed to measure the mechanical bonding or adhesion of thin coatings deposited on substrates. In the pull test, pins that have been bonded to the coating under test are pulled with increasing force normal to the coating until the coating is pulled from the substrate. For many systems, large scatter in the data is often observed due to uncontrolled defects in the interface and the brittle nature of the pull test. In this study, the applicability of Weibull statistical analysis to the adhesion of Ag coatings to vacuum sputter-cleaned zirconia was examined. Data were obtained for smooth and rough substrates for various levels of adhesion. A good fit of the data to the Weibull distribution was observed. The Weibull modulus was found to depend on the roughness of the substrate but was insensitive to the adhesion strength. This seems to be the first reported application of Weibull statistical analysis to pull test data. Presented at the 48th Annual Meeting in Calgary, Alberta, Canada...
Morphological adaptation to climate in modern and fossil hominids

Hominids—both living and past—exhibit considerable variation in body size and shape. Both theoretical considerations and empirical observations indicate that some of this variation may be attributable to climatic adaptation. Application of the simple thermoregulatory principle of increasing and decreasing body surface area/body mass in hot and cold climates, respectively, may explain the major systematic differences in body form between living and fossil hominids inhabiting tropical and higher latitude regions of the world. Consideration of potential climatic influences on morphology has important ramifications for reconstructing body form and behavior of past hominids, interpreting geographic and temporal variability and migrational events, explaining the origins and perfection of hominid bipedalism, and better understanding changes in brain size and encephalization during hominid evolution. © 1994 Wiley-Liss, Inc.
Impact of uncommanded effector motions on Shuttle consumables

Uncommanded thrust vectoring and aerosurface motions have concerned Space Shuttle designers, engineers, and flight planners since these motions were first discovered during early testing and flight simulation. These motions use hydraulic power and consume additional fuel. Clearly, uncommanded motion of these controls during Shuttle ascent, entry, and descent represents a potential impact to consumables margins and to payload weight. This article defines the two basic sources of uncommanded activity as hardware and flight controlrelated sources. The impact of these sources of uncommanded activity on consumables was successfully modeled by the authors. The model was also employed to allocate consumables reserves. The intent of the authors is to share with the reader the observed incidences of uncommanded activity, the formulation of the model, its application, and the reconciliation of model results with actual flight data.
An Empirical Investigation into the Performance of Ellickson's Random Bidding Model, with an Application to Air Quality Valuation

Abstract This paper compares Ellickson's random bidding model to the standard hedonic model in estimating benefits due to marginal and non-marginal changes in housing attributes. Using data on the Chicago housing market, the paper shows that the benefit estimates obtained using the two models are very close. In addition, various categorizations based on household characteristics are tested in the case of the random bidding model. The study shows that the effect of categorization on the overall benefit estimates are negligible. Moreover, the results from the random bidding model reveal that increased income leads to greater demand for environmental quality.
Lagrangian Averaging for Compressible Fluids

This paper extends the derivation of the Lagrangian averaged Euler (LAE-$\alpha$) equations to the case of barotropic compressible flows. The aim of Lagrangian averaging is to regularize the compressible Euler equations by adding dispersion instead of artificial viscosity. Along the way, the derivation of the isotropic and anisotropic LAE-$\alpha$ equations is simplified and clarified. The derivation in this paper involves averaging over a tube of trajectories $\eta^\epsilon$ centered around a given Lagrangian flow $\eta$. With this tube framework, the LAE-$\alpha$ equations are derived by following a simple procedure: start with a given action, Taylor expand in terms of small-scale fluid fluctuations $\xi$, truncate, average, and then model those terms that are nonlinear functions of $\xi$. Closure of the equations is provided through the use of flow rules, which prescribe the evolution of the fluctuations along the mean flow.
Forecasting the Distribution of Economic Variables in a Data-Rich Environment

This article investigates the relevance of considering a large number of macroeconomic indicators to forecast the complete distribution of a variable. The baseline time series model is a semiparametric specification based on the quantile autoregressive (QAR) model that assumes that the quantiles depend on the lagged values of the variable. We then augment the time series model with macroeconomic information from a large dataset by including principal components or a subset of variables selected by LASSO. We forecast the distribution of the h-month growth rate for four economic variables from 1975 to 2011 and evaluate the forecast accuracy relative to a stochastic volatility model using the quantile score. The results for the output and employment measures indicate that the multivariate models outperform the time series forecasts, in particular at long horizons and in tails of the distribution, while for the inflation variables the improved performance occurs mostly at the 6-month horizon. We also illustra...
Midlatitude storms in a moister world: lessons from idealized baroclinic life cycle experiments

The response of midlatitude storms to global warming remains uncertain. This is due, in part, to the competing effects of a weaker meridional surface temperature gradient and a higher low-level moisture content, both of which are projected to occur as a consequence of increasing greenhouse gases. Here we address the latter of these two effects, and try to elucidate the effect of increased moisture on the development and evolution of midlatitude storms. We do this with a set of highly controlled, baroclinic lifecycle experiments, in which atmospheric moisture is progressively increased. To assess the robustness of the results, the moisture content is changed in two different ways: first by using different initial relative humidity, and second by varying a parameter that we insert into the Clausius-Clapeyron equation. The latter method allows us to artificially increase the moisture content above current levels while keeping the relative humidity constant. Irrespective of how moisture is altered, we find that nearly all important measures of storm strength increase as the moisture content rises. Specifically, we examine the storm’s central pressure minimum, the strongest surface winds, and both extreme and accumulated precipitation rates. For all these metrics, increased moisture yields a stronger storm. Interestingly, we also find that when moisture is increased beyond current levels, the resulting storm has a reduced horizontal scale while its vertical extent increases. Finally, we note that for moisture increases comparable to those projected to occur by the end of the twentyfirst century, the actual amplitude of the increases in storm strength is relatively modest, irrespective of the specific measure one uses.
Diastereoselective synthesis of a key intermediate for the preparation of tricyclic β-lactam antibiotics

Abstract Asymmetric synthesis of ( S )- 5 has been accomplished with an excellent enantiomeric excess by hydrogenation of racemic 5 using ruthenium-BINAP-diamine-KOH system, followed by oxidation. Magnesium enolate of (2 S )-2-methoxycyclohexanone [( S )- 5 ] reacts with the 4-acetoxyazetidinone 4 to give the key intermediate 3 with high yield and diastereoselectivity for the synthesis of sanfetrinem 1 .
The development of chiral metallacrowns into anion recognition agents and porous materials

Abstract Chiral metallacrowns can be prepared by the reaction of resolved amino hydroxamic acids with divalent metal ions. The 15-metallacrown-5 structure is achieved by the reaction of α-amino hydroxamic acids (e.g. l -alanine hydroxamic acid, l -phenylalanine hydroxamic acid and l -tyrosine hydroxamic acid) with Cu(II) and a Ln(III) ion. If a resolved ligand is used, the structure obtained contains all sidechain functional groups on the same face of the metallamacrocycle. The metallacrowns made with l -phenylalanine hydroxamic acid and l -tyrosine hydroxamic acid dimerize in the solid state, forming cavities that selectively recognize anions. If one uses resolved β-aminohydroxamic acids (which have fused 5 and 6 membered chelate rings), chiral 12-MC-4 complexes can be realized. The resultant structure with β-phenylalanine hydroxamic acid and Cu(II) is remarkably similar in size and shape to Cu(II) tetraphenylporphyrin. These chiral units can be linked via Cu(II) paddle wheel dimers and nitrate to form microporous layered solids. Because the of the modular synthesis strategy, grams of solid with defined chiral centers can be prepared in excellent yield.
Nonlinear neutral inclusions: Assemblages of spheres

Abstract The problem of determining nonlinear neutral inclusions in (electrical or thermal) conductivity is considered. Neutral inclusions, inserted in a matrix containing a uniform applied electric field, do not disturb the field outside the inclusions. The well known Hashin coated sphere construction is an example of a neutral inclusion. In this paper, we consider the problem of constructing neutral inclusions from nonlinear materials. In particular, we discuss assemblages of coated spheres and the two-dimensional analogous problem of assemblages of coated disks.
Which nanowire couples better electrically to a metal contact: Armchair or zigzag nanotube?

The fundamental question of how chirality affects the electronic coupling of a nanotube to metal contacts is important for the application of nanotubes as nanowires. We show that metallic-zigzag nanotubes are superior to armchair nanotubes as nanowires, by modeling the metal–nanotube interface. More specifically, we show that as a function of coupling strength, the total electron transmission of armchair nanotubes increases and tends to be pinned close to unity for a metal with Fermi wave vector close to that of gold. In contrast, the total transmission of zigzag nanotubes increases to the maximum possible value of two. The origin of these effects lies in the details of the wave function, which is explained.
Antibiotic Treatment of Rhinitis and Sinusitis

The most common organisms causing bacterial sinusitis are pneumococci and Haemophilus influenzae. Accordingly, in a patient not allergic to penicillin, ampicillin or amoxicillin appears to be the a...
Synthesis of unnatural amino acids via Suzuki cross-coupling of enantiopure vinyloxazolidine derivatives.

(R and S )-α-Amino alcohols and α-amino acids, including 4-methoxyhomophenylalanine, with a variety of unnatural side chains have been synthesized via palladium-catalyzed cross-coupling Suzuki reactions. The key building blocks 1 and 2, synthesized from the common achiral precursor 2-butene-1,4-diol, were made enantiopure utilizing a Pseudomonas cepacia lipase-catalyzed kinetic resolution. The optimal conditions for the Suzuki cross-coupling and the subsequent oxidations of the resultant α-amino alcohols are described.
The dynamic birefringence of high polymers

Abstract : The time-dependence of birefringence was investigated in experiments involving relaxation at constant strain, extension at constant rate of strain, and periodically varying strain. The results of constant strain relaxation are calculated using the linear phenomenological theory of birefringence relaxation. Strain-optical coefficient spectra are calculated for a number of low and high density polyethylenes and characteristics of the spectra are correlated with sample density. A simple molecular theory is presented. The time-dependence of birefringence is believed to arise principally from the finite relaxation time for crystal orientation. (Author)
On quasi-reductive group schemes

This paper was motivated by a question of Vilonen, and the main results have been used by Mirkovic and Vilonen to give a geometric interpre- tation of the dual group (as a Chevalley group over Z) of a reductive group. We define a quasi-reductive group over a discrete valuation ring R to be an affine flat group scheme over R such that (i) the fibers are of finite type and of the same dimension; (ii) the generic fiber is smooth and connected, and (iii) the identity component of the reduced special fiber is a reductive group. We show that such a group scheme is of finite type over R, the generic fiber is a reductive group, the special fiber is connected, and the group scheme is smooth over R in most cases, for example when the residue characteristic is not 2, or when the generic fiber and reduced special fiber are of the same type as reductive groups. We also obtain results about group schemes over a Dedekind scheme or a Noetherian scheme. We show that in residue characteristic 2 there are non-smooth quasi-reductive group schemes with generic fiber SO2n+1 and they can be classified when R is strictly Henselian.
From Central Planning to Centrality: Krakow's Land Prices after Poland's Big Bang ⁄

We examine commercial land markets in Krakow, Poland over a ten-year period of transition from socialist management to a market economy. We explore the spatial and temporal evolution of land prices over this period. In particular, we are interested in identifying trends toward or away from centrality, and in discovering whether or not these trends acted on the city center alone or over a set of centers. The data set we employ is uniquely appropriate for this purpose as the densifying force of \highest-and-best" use - typically found in market-oriented cities - was absent under four decades of socialist planning, leaving undeveloped land scattered throughout the city. Free of quality-control issues associated with disentangling the value of land from properties in which land and structures are bundled, the data ofier a clean assessment of land prices within an urban area. We employ a novel, iterative approach to identify pricing centers -\nodes" of similarlysized residuals - which we interpret as evidence of omitted spatial amenities. Using this approach, we flnd that the price gradient in Krakow evolved towards concentration, but concentration in several centers rather than in just one. We flnd that the exclusion of proximity to these centers leads to biased coe‐cients in the hedonic regressions; we also flnd that the majority of the apparent spatial autocorrelation in the aspatial regressions results from the omission of proximity to these centers.
Private Pareto Optimal Exchange

We consider the problem of implementing an individually rational, asymptotically Pareto optimal allocation in a barter-exchange economy where agents are endowed with goods and preferences over the goods of others, but may not use money as a medium of exchange. Because one of the most important instantiations of such economies is kidney exchange -- where the "input" to the problem consists of sensitive patient medical records -- we ask to what extent such exchanges can be carried out while providing formal privacy guarantees to the participants. We show that individually rational allocations cannot achieve any non-trivial approximation to Pareto optimality if carried out under the constraint of differential privacy -- or even the relaxation of joint-differential privacy, under which it is known that asymptotically optimal allocations can be computed in two sided markets [Hsu et al. STOC 2014]. We therefore consider a further relaxation that we call marginal-differential privacy --which promises, informally, that the privacy of every agent i is protected from every other agent j ≠ i so long as j does not collude or share allocation information with other agents. We show that under marginal differential privacy, it is possible to compute an individually rational and asymptotically Pareto optimal allocation in such exchange economies.
A Simple Element for Aeroelastic Analysis of Undamaged and Damaged Wings

A one-dimensiona l finite element has been developed to study the aeroelastic behavior of wings of arbitrary geometry and material properties distribution ranging from beam plates to builtup box structures reinforced by stringers. The formulation takes into account the effect of transverse shear and the bending-stretching coupling inherent to unsymmetric composite structures and allows for unsymmetric cross sections. A modified aerodynamic strip theory along with the V-g method is used to solve the flutter equations. The formulation has been evaluated by solving a large number of problems available in the literature. An introductory study of the bending-stretching coupling introduced by unsymmetry and damage has been conducted. It was found that the unsymmetry can have a positive or a negative influence on the aeroelastic behavior of the structure and that this influence vanishes rapidly with a decrease in coupling. It is concluded that the unsymmetry of aeroelastic structures should be considered both during the tailoring process as an added degree of design freedom and during damage tolerance assessment.
LOCAL GROUP DWARF ELLIPTICAL GALAXIES. II. STELLAR KINEMATICS TO LARGE RADII IN NGC 147 AND NGC 185

We present kinematic and metallicity profiles for the M 31 dwarf elliptical (dE) satellite galaxies NGC 147 and NGC 185. The profiles represent the most extensive spectroscopic radial coverage for any dE galaxy, extending to a projected distance of 8 half-light radii (8r{sub eff} {approx} 14'). We achieve this coverage via Keck/DEIMOS multislit spectroscopic observations of 520 and 442 member red giant branch stars in NGC 147 and NGC 185, respectively. In contrast to previous studies, we find that both dEs have significant internal rotation. We measure a maximum rotational velocity of 17 +- 2 km s{sup -1} for NGC 147 and 15 +- 5 km s{sup -1} for NGC 185. While both rotation profiles suggest a flattening in the outer regions, there is no indication that we have reached the radius of maximum rotation velocity. The velocity dispersions decrease gently with radius with average dispersions of 16 +- 1 km s{sup -1} and 24 +- 1 km s{sup -1} for NGC 147 and NGC 185, respectively. The average metallicities for NGC 147 and NGC 185 are [Fe/H] = -1.1 +- 0.1 and [Fe/H] = -1.3 +- 0.1, respectively; both dEs have internal metallicity dispersions of 0.5 dex, but showmore » no evidence for a radial metallicity gradient. We construct two-{integral} axisymmetric dynamical models and find that the observed kinematical profiles cannot be explained without modest amounts of non-baryonic dark matter. We measure central mass-to-light ratios of M/L{sub V} = 4.2 +- 0.6 and M/L{sub V} = 4.6 +- 0.6 for NGC 147 and NGC 185, respectively. Both dE galaxies are consistent with being primarily flattened by their rotational motions, although some anisotropic velocity dispersion is needed to fully explain their observed shapes. The velocity profiles of all three Local Group dEs (NGC 147, NGC 185, and NGC 205) suggest that rotation is more prevalent in the dE galaxy class than previously assumed, but often manifests only at several times the effective radius. Since all dEs outside the Local Group have been probed to only inside the effective radius, this opens the door for formation mechanisms in which dEs are transformed or stripped versions of gas-rich rotating progenitor galaxies.« less
Informed Control Over Inputs and Extent of Industrial Processing

Abstract Industrial processing emphasizes information on and control over quality of raw materials. This letter establishes conditions under which informed control involves ensuring uniformity in inputs and increased uniformity encourages more extensive processing. The Boltzmann–Shannon entropy statistic can appropriately measure uniformity.
Absorption spectroscopic measurement of atomic density in laser‐induced vapor plume

Laser absorption spectroscopy employing a tunable continuous wave dye laser has been used to measure the density of atomic niobium vapor in a laser ablation plume near the target surface. Population densities for one atomic level were measured to be ∼2×1015 cm−3 near the center of the plume.
Chiral Amide Directed Assembly of a Diastereo- and Enantiopure Supramolecular Host and its Application to Enantioselective Catalysis of Neutral Substrates

The synthesis of a novel supramolecular tetrahedral assembly of K12Ga4L6 stoichiometry is reported. The newly designed chiral ligand exhibits high diastereoselective control during cluster formation, leading exclusively to a single diastereomer of the desired host. This new assembly also exhibits high stability toward oxidation or a low pH environment and is a more robust and efficient catalyst for asymmetric organic transformations of neutral substrates.
Molecular sensing using hyperpolarized xenon NMR spectroscopy

Molecular imaging is the determination of the spatial location and concentration of specific molecules in a sample of interest. Sophisticated modern magnetic resonance imaging machines can collect NMR spectra from small-volume elements within a sample, enabling local chemical analysis. However, abundant water and fat signals limit detection of metabolites to near mM concentrations. Alternatively, targeted relaxation contrast agents enhance the relaxation of the strong water signal where they bind. A comparison of images with and without a contrast agent shows the target distribution, but high µM concentrations are needed. We have developed an approach that exploits the strong signals of hyperpolarized 129Xe (an inert reporter introduced for imaging). The imaging contrast agents are composed of a biological recognition motif to localize the agent (antibodies or aptamers) and covalently tethered cryptophane cages. Xenon binds to the cryptophane and though chemical exchange saturation transfer creates contrast in a xenon image. Imaging agents can deliver many cages per target, giving detection limits in the pM concentration range. The evolution and principles of this approach are described herein.
Improved Hamiltonian for Minkowski Yang-Mills theory

Abstract I develop an improved Hamiltonian for classical, Minkowski Yang-Mills theory, which evolves infrared fields with tree level corrections from lattice spacing a beginning at O(a4). I use it to investigate the response of Chern-Simons number to a chemical potential, and to compute the maximal Lyapunov exponent. The Lyapunov exponent has a small a limit, and the Chern-Simons number response appears to be approaching one at the finest lattices considered. In both cases the limit is within 10% of the limit found using the unimproved (Kogut-Susskind) Hamiltonian. For the maximal Lyapunov exponent the limits differ between Hamiltonians by about 5%, significant at about 5σ, indicating that while a small a limit exists, its value depends on the specifics of the lattice cutoff. For Chern-Simons number the difference between Hamiltonians is within statistical errors of about 10%, which constitutes an upper bound on the lattice regulation dependence.
A one-flask multicomponent annulation reaction as the key step in a total synthesis of spirobicyclic (±)-β-vetivone

Abstract One-flask, 3-component Michael-Michael-Dieckmann cyclizations are applied to 2+2+2 construction of spirobicyclic cyclohexanone β-keto esters 7 and 11 as pivotal intermediates for synthesis of naturally-occurring spiro[4.5]decane β-vetivone ( 1 ). Some unexpected difficulties were encountered and are discussed. A novel BF 3 -promoted unidirectional dehydration of tertiary alcohol silyl ether 15 exclusively into isopropylidene cyclopentane 16 is reported.
Voting with one's feet: A brief note on the case of public welfare and the American Indian

This brief Note has found that the location decisions of the American Indian are influenced by geographic AFDC differentials. In particular, the American Indian population is apparently strongly attracted to high welfare areas. This finding may be interpreted as yet further support for the Tiebout hypothesis of ‘voting with one's feet,’ with the Indian consumer-voter in this case ‘balloting’ in terms of welfare services. In addition, like the studies by Cebula (1978), Chao and Renas (1975), Glantz (1974), Greenwood and Anderson (1974), Pack (1973), and Sommers and Suits (1973), this set of results provides additional evidence that the current welfare system distorts spatial resource allocation; presumably, such distortions are avoidable under a standardized welfare system.
Computational Geometry Column 44

The open problem of whether or not every pair of equal-area polygons has a hinged dissection is discussed.
Turbulence Modeling for Computational Aerodynamics

The status of turbulence modeling for external aerodynamic flows is reviewed, and closure concepts for the compressible form of the Reynolds-averaged Navier-Stokes equations are briefly outlined to establish a framework for comparison. The importance of experimental requirements for developing and verifying turbulence models is emphasized. Attention is then given to three important flow categories: attached flows, separating and reattaching flows, and trailing-edge flows. Examples of comparisons between experiments and computations for twoand three-dimensional flows are presented to illustrate the status of modeling. It is shown that, for most two-dimensional attached flows, eddy viscosity concepts will probably be adequate. For attached three-dimensional flows, however, eddy-viscosity and Reynolds-stress models are both deficient, failing to predict the proper surface shear-stress in rapidly skewing boundary layers, regardless of whether they are pressure driven or strain driven.
High-temperature mechanical properties and microstructures for hot-pressed silicon nitrides with amorphous and crystalline intergranular phases

Four-point flexure tests were performed at 1100° to 1350°C on two hot-pressed silicon nitrides, one in which the grain-boundary phase was amorphous and one in which it was largely crystalline. Fracture stress and relative K1c were plotted vs temperature. Fracture regions were analyzed by scanning and transmission electron microscopy. Grain-boundary phases affected high-temperature fracture significantly.
Residual Risk, Trading Costs, and Commodity Futures Risk Premia

Trading costs, in the form either of explicit charges or of the costs of becoming informed, limit the participation of some classes of traders in commodity futures markets. When speculators face a fixed cost of participating in a futures market that is used by commodity producers to hedge their stochastic revenues, the futures risk premium deviates from the perfect markets prediction. The deviation rises in absolute value with the square root of the trading cost and with the standard deviation of residual returns, and it is unrelated to the covariance of the futures price with producers' nonmarketable wealths. The residual-risk premium depends not on the total magnitude of the risk that producers hedge (i.e., aggregate revenue variance), but on the variability of their revenue relative to its mean (i.e., the coefficient of variation). Hence, even a commodity that constitutes a minor fraction of aggregate consumption may have a large premium for residual risk if the revenue derived from it has a large coefficient of variation.
The inverse of an automorphism in polynomial time

In this paper we present a polynomial time algorithm for computing the inverse of an automorphism over a polynomial ring K[x]. The algorithm works over any commutative ring K, and in the case when K is a field, provides an exponential time solution to the problem of determining when an endomorphism is invertible.
Transition fronts in inhomogeneous Fisher-KPP reaction-diffusion equations

Abstract We use a new method in the study of Fisher–KPP reaction–diffusion equations to prove existence of transition fronts for inhomogeneous KPP-type non-linearities in one spatial dimension. We also obtain new estimates on entire solutions of some KPP reaction–diffusion equations in several spatial dimensions. Our method is based on the construction of sub- and super-solutions to the non-linear PDE from solutions of its linearization at zero.
The Determinants and Implications of Mutual Fund Cash Holdings: Theory and Evidence

In this article, I examine the determinants and implications of equity mutual fund cash holdings. In cross-sectional tests, I find evidence generally supportive of a static trade-off model developed in the article. In particular, small-cap funds and funds with more-volatile fund flows hold more cash. However, I do not find that fund managers with better stock-picking skills hold less cash. Aggregate cash holdings by equity mutual funds are persistent and positively related to lagged aggregate fund flows. Aggregate cash holdings do not forecast future market returns, suggesting that equity funds as a whole do not have market timing skills.
Global hand pose estimation by multiple camera ellipse tracking

Immersive virtual environments with life-like interaction capabilities have very demanding requirements including high-precision motion capture and high-processing speed. These issues raise many challenges for computer vision-based motion estimation algorithms. In this study, we consider the problem of hand tracking using multiple cameras and estimating its 3D global pose (i.e., position and orientation of the palm). Our interest is in developing an accurate and robust algorithm to be employed in an immersive virtual training environment, called “Virtual GloveboX” (VGX) (Twombly et al. in J Syst Cybern Inf 2:30–34, 2005), which is currently under development at NASA Ames. In this context, we present a marker-based, hand tracking and 3D global pose estimation algorithm that operates in a controlled, multi-camera, environment built to track the user’s hand inside VGX. The key idea of the proposed algorithm is tracking the 3D position and orientation of an elliptical marker placed on the dorsal part of the hand using model-based tracking approaches and active camera selection. It should be noted that, the use of markers is well justified in the context of our application since VGX naturally allows for the use of gloves without disrupting the fidelity of the interaction. Our experimental results and comparisons illustrate that the proposed approach is more accurate and robust than related approaches. A byproduct of our multi-camera ellipse tracking algorithm is that, with only minor modifications, the same algorithm can be used to automatically re-calibrate (i.e., fine-tune) the extrinsic parameters of a multi-camera system leading to more accurate pose estimates.
Polar octahedral rotations: A path to new multifunctional materials

Abstract Perovskite ABO3 oxides display an amazing variety of phenomena that can be altered by subtle changes in the chemistry and internal structure, making them a favorite class of materials to explore the rational design of novel properties. Here we highlight a recent advance in which rotations of the BO6 octahedra give rise to a novel form of ferroelectricity – hybrid improper ferroelectricity. Octahedral rotations also strongly influence other structural, magnetic, orbital, and electronic degrees of freedom in perovskites and related materials. Octahedral rotation-driven ferroelectricity consequently has the potential to robustly control emergent phenomena with an applied electric field. The concept of ‘functional’ octahedral rotations is introduced and the challenges for materials chemistry and the possibilities for new rotation-driven phenomena in multifunctional materials are explored.
Studies of convertible turboshaft/turbofan engines for high-speed rotorcraft

Rotary wing aircraft require auxiliary thrust to fly at speeds higher than current helicopters. One approach is to use the turboshaft engine to drive both the vehicle rotor and a variable geometry fan which allows independent variation of shp and thrust. Various convertible engine configurations including variable pitch fans, variable inlet guide vane fans, and clutched fans are described and their suitability for two types of aircraft is examined. One is a 225 knot U.S. Army combat rotorcraft in which the rotor operates in high-speed flight. The variable inlet guide vane fan with or without a clutch is shown to be a viable approach. The second aircraft is a 400 knot X-wing commercial transport in which the rotor is stopped in flight. The variable inlet guide vane fan and prop/shaft systems are shown to be competitive.
A new modal method for the response of structures rotating in space

Abstract This paper presents a survey of various approaches to the response of flexible spacecraft. It also presents a modal analysis developed recently by this author that permits the derivation of closed-form response of rotating structures in a manner similar to that in which the classical modal analysis permits the derivation of the response of nonrotating structures. The method has important implications in the attitude dynamics and control of flexible spacecraft. As an illustration, the response of a spinning rigid body containing flexible parts is derived. This represents the first time that the response of a flexible gyroscopic system has been derived in closed form.
Predicting microstructure development during casting of drug-eluting coatings

We have devised a novel diffuse interface formulation to model the development of chemical and physical inhomogeneities, i.e. microstructure, during the process of casting drug-eluting coatings. These inhomogeneities, which depend on the coating constituents and manufacturing conditions, can have a profound affect on the rate and extent of drug release, and therefore the ability of coated medical devices to function successfully. By deriving the model equations in a time-dependent reference frame, we find that it is computationally viable to probe a wide, physically relevant range of material and process quantities. To illustrate the application of the model, we have evaluated the impact of manufacturing solvent, coating thickness and evaporation rate on microstructure development. Our results suggest that modifying these process conditions can have a strong and nearly discontinuous effect on coating microstructure, and therefore on drug release. Further, we demonstrate that the model can be applied to processes that involve the incremental application of the coating in layers or passes. This new model formulation, which can also be used to predict the kinetics of drug release, provides a tool to elucidate and quantify the relationships between process variables, microstructure and performance. Establishing these relationships can reduce empiricism in materials selection and process design, providing a facile and efficient means to tailor the underlying microstructure and achieve a desired drug-release behavior.