cssi/SciSciGPT-SciSciNet huggingface dataset:
Optical Observations of GRO J1655?40 in Quiescence. I. A Precise Mass for the Black Hole Primary

We report photometric and spectroscopic observations of the black hole binary GRO J1655-40 in complete quiescence. In contrast to the 1995 photometry, the light curves from 1996 are almost completely dominated by ellipsoidal modulations from the secondary star. Model fits to the light curves, which take into account the temperature profile of the accretion disk and eclipse effects, yield an inclination of i = 6950 ? 008 and a mass ratio of Q = M1/M2 = 2.99 ? 0.08. The precision of our determinations of i and Q allow us to determine the black hole mass to an accuracy of ? 4% (M1 = 7.02 ? 0.22 M?). The secondary star's mass is M2 = 2.34 ? 0.12 M?. The position of the secondary on the Hertzsprung-Russell diagram is consistent with that of a ? 2.3 M? star that has evolved off the main sequence and is halfway to the start of the giant branch. Using the new spectra, we present an improved value of the spectroscopic period (P = 262157 ? 000015), radial velocity semiamplitude (K = 228.2 ? 2.2 km s-1), and mass function [f(M) = 3.24 ? 0.09 M?]. Based on the new spectra of the source and spectra of several MK spectral type standards, we classify the secondary star as F3 IV-F6 IV. Evolutionary models suggest an average mass transfer rate for such a system of ${u{M}{"705F}}$ --> -->2=3.4?10 -->?9 M? yr-1 = 2.16 ? 1017 g s-1, which is much larger than the average mass transfer rates implied in the other six transient black hole systems but is still barely below the critical mass transfer rate required for stability.
Structure and screening in molecular and metallic hydrogen at high pressure

A variational wavefunction is used to express the (spin restricted) Hartree-Fock energy as reciprocal lattice sums for static lattice FCC monatomic hydrogen and diatomic Pa3 molecular hydrogen. In the monatomic phase the hydrogenic orbital range closely parallels the inverse Thomas-Fermi wavevector; the corresponding energy E has a minimum of -0.929 Ryd/electron at r sub s = 1.67. For the diatomic phase E(r sub s) is similar, but the constituent energies, screening, and bond length reflect a qualitative change in the nature of the solid at r sub s = 2.8. This change is interpreted in terms of a transition from protons as structural units (at high density) to weakly interacting models (at low density). Insensitivity of the total energy to a rapid fall in the bond length suggests association with the rotational transition where the rapid molecular orientations characteristic of high pressures disappear and the molecules rotate freely at low pressure.
CVC tests and CKM unitarity

The study of superallowed nuclear β -decay currently provides the most precise and convincing confirmation of the conservation of the vector current (CVC) and is a key component of the most demanding available test of the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, a basic pillar of the Electroweak Standard Model. The status of these fundamental studies is summarized and recent work described.
Future hadron physics facilities at Fermilab

Fermilab's hadron physics research continues in all its accelerator-based programs. These efforts will be identified, and the optimization of the Fermilab schedules for physics will be described. In addition to the immediate plans, the Fermilab Long Range Plan will be cited, and the status and potential role of a new proton source, the Proton Driver, will be described.
X-ray astronomy in the new millennium: a summary

Recent X–ray observations have had a major impact on topics ranging from proto–stars to cosmology. They have also drawn attention to important and general physical processes that currently limit our understanding of thermal and non–thermal X–ray sources. These include unmeasured atomic astrophysics data (wavelengths, oscillator strengths, etc.), basic hydromagnetic processes (e.g. shock structure, reconnection), plasma processes (such as electron–ion equipartition and heat conduction) and radiative transfer (in discs and accretion columns). Progress on these problems will probably come from integrative studies that draw upon observations, throughout the electromagnetic spectrum, of different classes of source. X–ray observations are also giving a new perspective on astronomical subjects, like the nature of galactic nuclei and the evolution of stellar populations. In addition, they are helping us to address central cosmological questions, including the measurement of the matter content of the Universe, understanding its overall luminosity density, describing its chemical evolution and locating the first luminous objects. X–ray astronomy has a healthy future with several international space missions under construction and in development.
A vortex-grid method for blood flow through heart valves

Abstract A combination vortex-grid method for solving the two-dimensional, incompressible Navier-Stokes equations in regions with complicated internal, elastic boundaries is presented. The authors believe the method to be applicable to the case of at least moderately high Reynolds number flow. The method is applied to the study of blood flow through the mammalian mitral valve. Previous work of Peskin is extended and the conjecture that the behavior of mammalian heart valves is independent of Reynolds number is supported.
Algebraic and combinatorial aspects of sandpile monoids on directed graphs

The sandpile group of a graph is a well-studied object that combines ideas from algebraic graph theory, group theory, dynamical systems, and statistical physics. A [email protected]?s sandpile group is part of a larger algebraic structure on the graph, known as its sandpile monoid. Most of the work on sandpiles so far has focused on the sandpile group rather than the sandpile monoid of a graph, and has also assumed the underlying graph to be undirected. A notable exception is the recent work of Babai and Toumpakari, which builds up the theory of sandpile monoids on directed graphs from scratch and provides many connections between the combinatorics of a graph and the algebraic aspects of its sandpile monoid. In this paper we primarily consider sandpile monoids on directed graphs, and we extend the existing theory in four main ways. First, we give a combinatorial classification of the maximal subgroups of a sandpile monoid on a directed graph in terms of the sandpile groups of certain easily-identifiable subgraphs. Second, we point out certain sandpile results for undirected graphs that are really results for sandpile monoids on directed graphs that contain exactly two idempotents. Third, we give a new algebraic constraint that sandpile monoids must satisfy and exhibit two infinite families of monoids that cannot be realized as sandpile monoids on any graph. Finally, we give an explicit combinatorial description of the sandpile group identity for every graph in a family of directed graphs which generalizes the family of (undirected) distance-regular graphs. This family includes many other graphs of interest, including iterated wheels, regular trees, and regular tournaments.
Thermal Characterization of a Direct Gain Solar Thermal Engine

A thermal/fluids analysis of a direct gain solar thermal upper stage engine is presented and the results are discussed. The engine was designed and constructed at the NASA Marshall Space Flight Center for ground testing in a facility that can provide about 10 kilowatts of concentrated solar energy to the engine. The engine transfers energy to a coolant (hydrogen) that is heated and accelerated through a nozzle to produce thrust. For the nominal design values and a hydrogen flowrate of 2 lb./hr., the results of the analysis show that the hydrogen temperature in the chamber (nozzle entrance) reaches about 3800 F after 30 minutes of heating and about 3850 F at steady-state (slightly below the desired design temperature of about 4100 F. Sensitivity analyses showed these results to be relatively insensitive to the values used for the absorber surface infrared emissivity and the convection coefficient within the cooling ducts but very sensitive to the hydrogen flowrate. Decreasing the hydrogen flowrate to 1 lb./hr. increases the hydrogen steady-state chamber temperature to about 4700 F, but also of course causes a decrease in thrust.
Alkynes as Stille reaction pseudohalides: gold- and palladium-cocatalyzed synthesis of tri- and tetra-substituted olefins.

A Stille-type reaction that employs alkynes as pseudohalides provides access to the catalytic chemistry of palladium−carbon σ-bonds starting from π-systems. The synthesis of a variety of tri- and tetra-substituted olefins by addition of sp2- and sp-hybridized stannanes across mono- and diester alkynes was accomplished with complete regioselectivity and high stereoselectivity. The reaction is proposed to proceed via a bimetallic mechanism where the Lewis acidic Au(I) activates the alkyne toward oxidative addition across Pd(0).
Pauli Diagonal Channels Constant on Axes

We define and study the properties of channels which are analogous to unital qubit channels in several ways. A full treatment can be given only when the dimension d = pm a prime power, in which case each of the d + 1 mutually unbiased bases (MUB) defines an axis. Along each axis the channel looks like a depolarizing channel, but the degree of depolarization depends on the axis. When d is not a prime power, some of our results still hold, particularly in the case of channels with one symmetry axis. We describe the convex structure of this class of channels and the subclass of entanglement breaking channels. We find new bound entangled states for d = 3. For these channels, we show that the multiplicativity conjecture for maximal output p-norm holds for p = 2. We also find channels with behaviour not exhibited by unital qubit channels, including two pairs of orthogonal bases with equal output entropy in the absence of symmetry. This provides new numerical evidence for the additivity of minimal output entropy.
TRANSPORT BY MERIDIONAL CIRCULATIONS IN SOLAR-TYPE STARS

Transport by meridional flows has significant consequences for stellar evolution, but is difficult to capture in global-scale numerical simulations because of the wide range of timescales involved. Stellar evolution models therefore usually adopt parameterizations for such transport based on idealized laminar or mean-field models. Unfortunately, recent attempts to model this transport in global simulations have produced results that are not consistent with any of these idealized models. In an effort to explain the discrepancies between global simulations and idealized models, here we use three-dimensional local Cartesian simulations of compressible convection to study the efficiency of transport by meridional flows below a convection zone in several parameter regimes of relevance to the Sun and solar-type stars. In these local simulations we are able to establish the correct ordering of dynamical timescales, although the separation of the timescales remains unrealistic. We find that, even though the generation of internal waves by convective overshoot produces a high degree of time dependence in the meridional flow field, the mean flow has the qualitative behavior predicted by laminar, balanced models. In particular, we observe a progressive deepening, or burrowing, of the mean circulation if the local Eddington-Sweet timescale is shorter than the viscous diffusion timescale. Such burrowing is a robust prediction of laminar models in this parameter regime, but has never been observed in any previous numerical simulation. We argue that previous simulations therefore underestimate the transport by meridional flows.
ASCA Observations of Seyfert 1 Galaxies. I. Data Analysis, Imaging, and Timing

We present the first in a series of papers describing the X-ray properties of a sample of 18 Seyfert 1 galaxies, using data obtained by ASCA. The imaging data reveal a number of serendipitous hard X-ray sources in some source fields, but none contribute significantly to the hard X-ray flux of the active galactic nuclei. All but one of the Seyferts show evidence for variability on timescales of minutes to hours, with the amplitude anticorrelated with the source luminosity, confirming previous results. In at least eight sources there is evidence that the variability amplitude below 2 keV is greater than that in the hard X-ray band, perhaps indicating variable components other than the power law in the soft band. Ultrarapid variability, implying significant power at frequencies greater than 10-3 Hz is detected in at least five sources but is difficult to detect in most cases, because of the sampling and signal-to-noise ratio. In Mrk 766 and MCG -6-30-15 there is also an indication that the high-frequency power spectra are variable in shape and/or intensity. There is similar evidence in NGC 4151 but on longer timescales.
Quasi-Stellar Sources: Variation in the Radio Emission of 3C 273

Evidence is presented for the first time for large fractional variations in the radio emission of the quasi-stellar sources 3C 273, 3C 279, and 3C 345, all of which have flat radio spectra at centimeter wavelengths.
The Diffie---Hellman problem and generalization of Verheul's theorem

Bilinear pairings on elliptic curves have been of much interest in cryptography recently. Most of the protocols involving pairings rely on the hardness of the bilinear Diffie---Hellman problem. In contrast to the discrete log (or Diffie---Hellman) problem in a finite field, the difficulty of this problem has not yet been much studied. In 2001, Verheul (Advances in Cryptology--EUROCRYPT 2001, LNCS 2045, pp. 195---210, 2001) proved that on a certain class of curves, the discrete log and Diffie---Hellman problems are unlikely to be provably equivalent to the same problems in a corresponding finite field unless both Diffie---Hellman problems are easy. In this paper we generalize Verheul's theorem and discuss the implications on the security of pairing based systems.
Controlling teenagers' drinking: Effects of a community-based prevention project

Aims: The study presents the evaluation results of the age-limit component of a community-based prevention project called PAKKA. The project aimed to reduce alcohol availability among those under 18, which is the legal age for purchasing alcohol. The interventions consisted of law enforcement, community coalitions and community mobilization.Data and methods: The effects of the interventions were measured in a quasi-experimental research-setting with a matched control area before (2004) and after (2006/7) the interventions. The data included under-age purchase trials, a population survey and a school-based survey.Results: According to the purchase trials, the age limit control in the shops improved between the measuring points, and the young people reported in surveys that it had become more difficult to obtain alcohol. However, changes in the intervention and the control areas were similar. This can partly be explained by increased surveillance in addition to spill-over effects of PAKKA-interventions into...
Reversible optical computing circuits

Planar optical implementations of binary adders are developed using a three-port nonlinear interface device as the single computing primitive. The device is bit-conserving and both optically and logically reversible.
Modified Exit-ply Delamination Model for Drilling FRPs

Delamination has been identified as one of the most deleterious damage processes associated with drilling fiber reinforced plastics (FRPs) due to the resulting drastic reduction of structural strength and stiffness. In recent years, several experimental, numerical, and analytical studies have been conducted aimed at understanding delamination initiation and progression during drilling. In this study, a comprehensive review of existing analytical studies has been presented comparing and contrasting their respective advantages and disadvantages. Special emphasis has been laid upon presenting all assumptions made and the underlying implications thereby. Suggestions at improving the existing models so as to facilitate a more realistic description of the drill process using composite lamination theories have also been included.
A statistical modeling framework for projecting future ambient ozone and its health impact due to climate change

The adverse health effects of ambient ozone are well established. Given the high sensitivity of ambient ozone concentrations to meteorological conditions, the impacts of future climate change on ozone concentrations and its associated health effects are of concern. We describe a statistical modeling framework for projecting future ozone levels and its health impacts under a changing climate. This is motivated by the continual effort to evaluate projection uncertainties to inform public health risk assessment. The proposed approach was applied to the 20-county Atlanta metropolitan area using regional climate model (RCM) simulations from the North American Regional Climate Change Assessment Program. Future ozone levels and ozone-related excesses in asthma emergency department (ED) visits were examined for the period 2041-2070. The computationally efficient approach allowed us to consider 8 sets of climate model outputs based on different combinations of 4 RCMs and 4 general circulation models. Compared to the historical period of 1999-2004, we found consistent projections across climate models of an average 11.5% higher ozone levels (range: 4.8%, 16.2%), and an average 8.3% (range: -7% to 24%) higher number of ozone exceedance days. Assuming no change in the at-risk population, this corresponds to excess ozone-related ED visits ranging from 267 to 466 visits per year. Health impact projection uncertainty was driven predominantly by uncertainty in the health effect association and climate model variability. Calibrating climate simulations with historical observations reduced differences in projections across climate models.
Order Statistics and Benford's Law

Fix a base and let have the standard exponential distribution; the distribution of digits of base is known to be very close to Benford's law. If there exists a such that the distribution of digits of times the elements of some set is the same as that of , we say that set exhibits shifted exponential behavior base Let be i.i.d.r.v. If the 's are Unif, then as the distribution of the digits of the differences between adjacent order statistics converges to shifted exponential behavior. If instead 's come from a compactly supported distribution with uniformly bounded first and second derivatives and a second-order Taylor series expansion at each point, then the distribution of digits of any consecutive differences and all normalized differences of the order statistics exhibit shifted exponential behavior. We derive conditions on the probability density which determine whether or not the distribution of the digits of all the unnormalized differences converges to Benford's law, shifted exponential behavior, or oscillates between the two, and show that the Pareto distribution leads to oscillating behavior.
RECENT STUDIES OF THE NUCLEAR INTERACTION

Recent studies of light p-shell nuclei reveal that so-called 'realistic' nuclear interactions, those based on the NN scattering data augmented with plausible models of the three-nucleon interaction, provide a good description or nuclei through A=8. However, significant discrepancies exist, primarily in the energies of neutron rich systems and in the L.S splittings in the spectra of these nuclei. We briefly describe the methods used in these studies, and describe improved models of the three-nucleon interaction.
An Experimental Transistor Personal Broadcast Receiver

This paper describes a laboratory model AM broadcast receiver which used nine alloy junction transistors and two compensating diodes. Six of the transistors were of the laboratory P-N-P type, designed for radio-frequency-amplifiers, and three of the transistors were of the conventional P-N-P type selected for Class B audio driver and output service. The use of Class B output permitted a total battery drain below 12 milliamperes from six 1.5 volt type C cells in series. The battery life was ap?roximately 500 hours, and the battery cost relatively small. The maximum audio power output was 150 milliwatts into a four-inch by six-inch oval speaker. The sensitivity and signal-to-noise ratio were comparable to that of conventional battery-operated receivers and conventional ac-dc receivers. The receiver may be used in the place of ac-dc receivers without the necessity of a power outlet or a connecting power cord at a battery cost approximately the same as the cost of power for an ac-dc receiver.
International Systems, Domestic Structures, and Risk

Why do some states embark on risky policies that appear certain to lead to disastrous outcomes while others seem more cautious as they interact with others in the international system? This is a central question that faces policymakers and one that has remained largely unexplored by scholars of international relations. This article argues that democratic peace theory speaks to the central factors that affect the risk preferences of states. Countries involved in Europe from 1816 to 1992 are analyzed to determine if levels of democracy and its constitutive elements affect risk-taking. Since critics argue that the strategic context affects the mechanisms underpinning explanations of the democratic peace, the effects of strategic variables on the relationships between regime type and risk-taking propensity are evaluated. Competing propositions are evaluated empirically using Bueno de Mesquita's indicator of risk with the EUGene dataset, which combines the Correlates of War and the Polity III data regarding regime type developed by Jaggers and Gurr. The results support the central hypothesis of the article - democracy is indeed associated with risk aversion regardless of the strategic context. However, the findings also suggest that states undergoing the transition to democracy from autocracy are more willing to take risks than are states with more stable forms of government. Further, the constitutive components of democracy have divergent effects on risk preferences.
Unconstrained Online Linear Learning in Hilbert Spaces: Minimax Algorithms and Normal Approximations

We study algorithms for online linear optimization in Hilbert spaces, focusing on the case where the player is unconstrained. We develop a novel characterization of a large class of minimax algorithms, recovering, and even improving, several previous results as immediate corollaries. Moreover, using our tools, we develop an algorithm that provides a regret bound ofO U q T log(U p T log 2 T + 1) , where U is the L2 norm of an arbitrary comparator and both T and U are unknown to the player. This bound is optimal up to p log logT terms. When T is known, we derive an algorithm with an optimal regret bound (up to constant factors). For both the known and unknown T case, a Normal approximation to the conditional value of the game proves to be the key analysis tool.
Calculation Of Surface Statistics From Light Scatter

The operation of a differential scatterometer developed at Montana State University is briefly described. The scatterometer takes and stores data under computer control. Analysis routines allow calculation of the surface power spectral density (PSD) function for the cases of one-dimensional surfaces [Z(x) - diamond-turned surfaces, for example] and isotropic two-dimensional surfaces [ Z(x,y) - polished surfaces, for example] . In addition, the zero and second moments of the PSD may be taken to provide bandwidth-limited values of the root mean square roughness (cr) and the root mean square slope (m). Results from several samples are used to check the vector perturbation theory [E. L. Church and J. M. Zavada, Appl. Opt. 14, 1788 (1975)] used by the computer to relate the scatter distribution function to the PSD. These experiments take advantage of the fact that the surface - and hence its PSD - remain a constant function during the measurements. Variations in the incident angle and polarization are introduced, and the resulting PSDs are calculated and compared. In another experiment, the min/max scatter angles (or, conversely, the min/max PSD spatial frequencies) are matched to those of a total integrated scatter (TIS) system. Integration over the light scatter data and the PSD allows direct comparison to the TIS and effective rms roughness obtained by the TIS system.
Criminal behavior and r/K selection: An extension of gene-based evolutionary theory

An r-selected approach to reproduction emphasizes producing large numbers of offspring with minimal care given to each offspring by its parents. At the other end of the continuum, K-selection is an approach in which few offspring are produced, but maximal care is taken to insure reproductive viability of each offspring. This article argues that several heretofore seemingly unrelated factors which have been found associated with serious victimful criminal behavior (i.e. serious violent and property offenses) in numerous countries are predictable by hypothesizing that criminal behavior is part of an r-selected approach to reproduction.
Stochastic modelling of remotely manned systems

Abstract This report describes a new technique to model remotely controlled systems (Remotely manned systems) in which man is an element of the control loop. It is proposed to model macroscopically the system as a group of stochastic system elements with the objective to predict times to complete a task. Various candidate models are proposed with the ultimate objective of selecting one or more for refinement and greates utility. A simulation model is proposed, and recommendations are made how to verify the analyses.
Automated population‐based planning for whole brain radiation therapy

Treatment planning for whole-brain radiation treatment is technically a simple process, but in practice it takes valuable clinical time of repetitive and tedious tasks. This report presents a method that automatically segments the relevant target and normal tissues, and creates a treatment plan in only a few minutes after patient simulation. Segmentation of target and critical structures is performed automatically through morphological operations on the soft tissue and was validated by comparing with manual clinical segmentation using the Dice coefficient and Hausdorff distance. The treatment plan is generated by searching a database of previous cases for patients with similar anatomy. In this search, each database case is ranked in terms of similarity using a customized metric designed for sensitivity by including only geometrical changes that affect the dose distribution. The database case with the best match is automatically modified to replace relevant patient info and isocenter position while maintaining original beam and MLC settings. Fifteen patients with marginally acceptable treatment plans were used to validate the method. In each of these cases the anatomy was accurately segmented, but the beams and MLC settings led to a suboptimal treatment plan by either underdosing the brain or excessively irradiating critical normal tissues. For each case, the anatomy was automatically segmented with the proposed method, and the automated and anual segmentations were then compared. The mean Dice coefficient was 0.97, with a standard deviation of 0.008 for the brain, 0.85 ± 0.009 for the eyes, and 0.67 ± 0.11 for the lens. The mean Euclidian distance was 0.13 ± 0.13 mm for the brain, 0.27± 0.31 for the eye, and 2.34 ± 7.23 for the lens. Each case was then subsequently matched against a database of 70 validated treatment plans and the best matching plan (termed autoplanned), was compared retrospectively with the clinical plans in terms of brain coverage and maximum doses to critical structures. Maximum doses were reduced by a maximum of 8.37 Gy for the left eye (mean 2.08), 11.67 for the right eye (1.90) and, respectively, 25.44 (5.59) for the left lens and 24.40 (4.85) for the right lens. Time to generate the autoplan, including the segmentation, was 3-4min. Automated database- based matching is an alternative to classical treatment planning that improves quality while providing a cost-effective solution to planning through modifying previous validated plans to match a current patient's anatomy.
The orbit method for profinite groups and a p -adic analogue of Brown’s theorem

We develop an approach to the character theory of certain classes of finite and profinite groups based on the construction of a Lie algebra associated to such a group, but without making use of the notion of a polarization which is central to the classical orbit method. Instead, Kirillov’s character formula becomes the fundamental object of study. Our results are then used to produce an alternate proof of the orbit method classification of complex irreducible representations of p-groups of nilpotence class < p, where p is a prime, and of continuous complex irreducible representations of uniformly powerful pro-p-groups (with a certain modification for p = 2). As a main application, we give a quick and transparent proof of the p-adic analogue of Brown’s theorem, stating that for a nilpotent Lie group over ℚp the Fell topology on the set of isomorphism classes of its irreducible representations coincides with the quotient topology on the set of its coadjoint orbits.
Verification of Embedded Memory Systems using Efficient Memory Modeling

We describe verification techniques for embedded memory systems using efficient memory modeling (EMM), without explicitly modeling each memory bit. We extend our previously proposed approach of EMM in bounded model checking (BMC) for a single read/write port single memory system, to more commonly occurring systems with multiple memories, having multiple read and write ports. More importantly, we augment such EMM to providing correctness proofs, in addition to finding real bugs as before. The novelties of our verification approach are in (a) combining EMM with a proof-based abstraction that preserves the correctness of a property up to a certain analysis depth of SAT-based BMC, and (b) modeling arbitrary initial memory state precisely and thereby providing inductive proofs using SAT-based BMC for embedded memory systems. Similar to the previous approach, we construct a verification model by eliminating memory arrays, but retaining the memory interface signals with their control logic and adding constraints on those signals at every analysis depth to preserve the data forwarding semantics. The size of these EMM constraints depends quadratically on the number of memory accesses and the number of read and write ports; and linearly on the address and data widths and the number of memories. We show the effectiveness of our approach on several industry designs and software programs.
Recovering precision from seemingly redundant rounded data

Economic time series from the socialist economies of Eastern Europe and the Soviet Union are often not available. Instead, a matrix of rounded growth indexes for different base years is published. Using the constrained least squares and feasible GLS estimators developed in this paper, it is possible to predict the true matrix of growth indexes with greatly improved accuracy.
Selenium Deficiency in Soils and Its Effect on Animal Health

Selenium in minute quantities has been shown to be a dietary essential for animal life, and soil-plant-animal relations have been identified in the distribution of the element. In some cases, soils are frankly deficient in selenium—most particularly those derived from igneous rocks, and the deficiency in surface layers may be aggravated by intensive irrigation. Alternatively, soil selenium may exist in a form that is either unavailable to plants or absorbed by them with difficulty. Representative of such a form is the highly insoluble ferric oxide-selenite complex which frequently occurs in high-moisture, acid soils. Uptake of selenium by plants may also be inhibited by presence of interfering substances in the soil, such as sulphur, or it may be enhanced by liming. Analytical surveys have revealed also that considerable variation exists among plant species in their abilities to take up and retain selenium from the soil. Legumes have been consistently implicated as forages conducive to white muscle disease, a selenium-responsive myopathy, and New Zealand observations have shown white clover (Trifolium repens L.) to contain significantly lower levels of selenium than grasses, and particularly a native grass, browntop (Agrostis tenuis Sibth.). In addition to the differences in absolute selenium uptake, it has been suggested that some plants, and again legumes are suspect, may contain organic inhibitors of selenium utilization by livestock. Some experiments have investigated the effectiveness of additions of selenium to the soil in overcoming selenium deficiency among farm animals. Protection for 2 yrs has been achieved by this technique; however, the various factors influencing the soil-plant-animal relations of selenium direct caution in its application.
Using simplicial volume to count multi-tangent trajectories of traversing vector fields

For a non-vanishing gradient-like vector field on a compact manifold $$X^{n+1}$$ with boundary, a discrete set of trajectories may be tangent to the boundary with reduced multiplicity n, which is the maximum possible. (Among them are trajectories that are tangent to $$\partial X$$ exactly n times.) We prove a lower bound on the number of such trajectories in terms of the simplicial volume of X by adapting methods of Gromov, in particular his “amenable reduction lemma”. We apply these bounds to vector fields on hyperbolic manifolds.
An efficient long-lived adaptive collect algorithm

Adaptive algorithms, whose step complexity adjusts to the number of actually participating processors, are attractive in distributed systems where the number of processors is highly variable. Long-lived adaptive algorithms moreover enable processors to repeatedly execute operations "from scratch", allowing for stronger forms of adaptiveness. Shared memory collect can be implemented non adaptively with step and memory complexity O(N). To date, the best known long-lived and adaptive shared memory collect algorithm has worst case step complexity O(k/sup 3/) and requires O(N/sup 3/) shared memory registers where k is the interval contention of a collect operation and N the number of processors in the system. Hence, if the interval contention k rises above K such that K/sup 3//spl Gt/N this algorithm becomes inefficient. In this paper, we present a new long-lived, efficient, adaptive collect algorithm. Namely, our algorithm adapts to K-contention - it has the property that if during an operation the interval contention k exceeds a predetermined constant K the step complexity is O(N). If it falls below K, the processors executions eventually have adaptive step complexity of O(k/sup 3/). Moreover, for K such that K3/spl les/N our algorithm requires only O(N/sup 2/) shared memory registers.
On universal types

The universal type class of a sequence xn is defined, in analogy to the notion underlying the classical method of types. Two sequences of the same length are said to be of the same universal (LZ) type if and only if they yield the same dictionary (or, equivalently, parsing tree) in the incremental parsing of Ziv and Lempel (1978). It is shown that for any finite order k, the variational distance between the kth-order empirical probability distributions of two sequences of the same universal type vanishes as the sequence length tends to infinity. Consequently, for any k and any kth-order probability assignment, the difference between the normalized logarithms of the probabilities assigned to two sequences of the same universal type also vanishes asymptotically. The size of a universal type class is studied, and it is shown that its asymptotic behavior parallels that of the conventional counterpart, with the LZ78 code length playing the role of the empirical entropy. The number of universal types for sequences of length n is estimated, and shown to be of the form exp((1+o(1))gamman/logn) for a well characterized constant gamma. Algorithms for enumerating the sequences in a universal type class, and for drawing a sequence from the class with uniform probability are described. As an application, the problem of universal simulation of individual sequences is considered. A sequence drawn with uniform probability from the universal type class of xn is an optimal simulation of xn in a well defined mathematical sense
Review of Attitude Representations Used for Aircraft Kinematics

Adetailed survey ispresentedoftheliteratureonattituderepresentationdatingfromtheearlyworkofEulerand Hamilton to recent publications in e elds such as navigation and control. The scope is limited to the development of the aircraft kinematic transformation equations in terms of four different attitude representations, including the well-known Euler angles, the Euler-axis rotation parameters, the direction cosines, and the Euler ‐Rodrigues quaternion.Theemphasisisdirectedattheapplicationofthequaternionformulationtoaircraftkinematics.Results are presented that reinforce observations that the quaternion formulation, typically implemented to eliminate singularities associated with the Euler angle formulation, is far superior to the other commonly used formulations based on computational efe ciency alone. A development of quaternion constraints necessary to independently constrain roll, pitch, yaw, bank angle, elevation angle, and/or azimuth angle is presented. For verie cation of simulation codes, a general closed-form solution to the quaternion formulation, for the case of constant rotation, is also presented. Additionally, a discussion is provided of numerical integration methods and numerical errors for the quaternion formulation. This discussion is especially important for simulations that may still utilize a common error reduction scheme originally developed for analog computers.
IMPROVING GALACTIC CENTER ASTROMETRY BY REDUCING THE EFFECTS OF GEOMETRIC DISTORTION

We present significantly improved proper motion measurements of the Milky Way’s central stellar cluster. These improvements are made possible by refining our astrometric reference frame with a new geometric optical distortion model for the W. M. Keck II 10 m telescope’s adaptive optics camera (NIRC2) in its narrow field mode. For the first time, this distortion model is constructed from on-sky measurements and is made available to the public in the form of FITS files.When applied to widely dithered images, it produces residuals in the separations of stars that are a factor of ~3 smaller compared with the outcome using previous models. By applying this new model, along with corrections for differential atmospheric refraction, to widely dithered images of SiO masers at the Galactic center (GC), we improve our ability to tie into the precisely measured radio Sgr A*-rest frame. The resulting infrared reference frame is ~2–3 times more accurate and stable than earlier published efforts. In this reference frame, Sgr A* is localized to within a position of 0.6 mas and a velocity of 0.09 mas yr^(−1), or ~3.4 km s^(−1) at 8 kpc (1σ). Also, proper motions for members of the central stellar cluster are more accurate, although less precise, due to the limited number of these wide field measurements. These proper motion measurements show that, with respect to Sgr A*, the central stellar cluster has no rotation in the plane of the sky to within 0.3 mas yr^(−1) arcsec^(−1), has no net translational motion with respect to Sgr A* to within 0.1 mas yr^(−1), and has net rotation perpendicular to the plane of the sky along the Galactic plane, as has previously been observed. While earlier proper motion studies defined a reference frame by assuming no net motion of the stellar cluster, this approach is fundamentally limited by the cluster’s intrinsic dispersion and therefore will not improve with time.We define a reference frame with SiO masers and this reference frame’s stability should improve steadily with future measurements of the SiO masers in this region (∝t^(−3/2)). This is essential for achieving the necessary reference frame stability required to detect the effects of general relativity and extended mass on short-period stars at the GC.
Estate Taxation with Altruism Heterogeneity

We develop a theory of optimal estate taxation in a model where bequest inequality is driven by differences in parental altruism. We show that a wide range of results are possible, from positive taxes to subsidies, depending on redistributive objectives implicit in the cardinal specification of utility and social welfare functions. We propose a normalization that is helpful in classifying these different possibilities. We isolate cases where the optimal policy bans negative bequests and taxes positive bequests, features present in most advanced countries.
Local well-posedness of the Yang-Mills equation in the temporal gauge below the energy norm

Abstract We show that the Yang–Mills equation in three dimensions in the temporal gauge is locally well-posed in Hs for s> 3 4 if the Hs norm is sufficiently small. The temporal gauge is slightly less convenient technically than the more popular Coulomb gauge, but has the advantage of uniqueness even for large initial data, and does not require solving a nonlinear elliptic problem. To handle the temporal gauge correctly we project the connection into curl- and divergence-free components, and develop some new bilinear estimates of Xs,b type which can handle integration in the time direction.
Nonparametric Estimation from Cross-Sectional Survival Data

Abstract In many follow-up studies survival data are often observed according to a cross-sectional sampling scheme. Data of this type are subject to left truncation in addition to the usual right censoring. A number of characteristics and properties of the product-limit estimate, for left-truncated and right-censored data, have been explored and found to be similar to those of the Kaplan-Meier estimate. Under the stationarity assumption, however, it is believed that an alternative estimate has much better efficiency. In this article the conditional maximum likelihood estimate (MLE) property of the product-limit estimate is visited. The non-parametric MLE of the truncation distribution is derived. Use of this estimate includes testing the stationarity assumption, estimating the proportion of truncated data, and other applications in prevalent cohort studies. The analysis of the estimation is based on a “working data” approach. The asymptotic properties of the proposed estimates are developed through nonpar...
Naturalistic Instructional Approaches in Early Learning: A Systematic Review

Naturalistic instructional approaches are used to provide intentional and systematic instruction to young children with disabilities during typically occurring activities. Several naturalistic instructional approaches have been described in the extant literature, although different terms have been used to refer to these approaches (e.g., activity-based intervention, embedded instruction). The purpose of this systematic review was to identify, examine, and summarize the empirical literature focused on naturalistic instructional approaches for preschool children with disabilities when instruction was delivered in classroom settings. Forty-three studies that met established inclusion criteria were reviewed and coded using systematic procedures. Studies were coded to permit within- and across-approach comparisons as well as with respect to quality indicators for study design features and relationships to reported outcomes. Findings suggest a need to specify clearly the contextual and procedural components of ...
Governing the Globalization of Public Health

The number and the scale of transboundary public health concerns are increasing. Infectious and non-communicable diseases, international trade in tobacco, alcohol, and other dangerous products as well as the control of the safety of health services, pharmaceuticals, and food are merely a few examples of contemporary transnationalization of health concerns. The rapid development and diffusion of scientific and technological developments across national borders are creating new realms of international health concern, such as aspects of biomedical science, including human reproductive cloning, germ-line therapy, and xenotransplantation, as well as environmental health problems, including climate change, biodiversity loss, and depletion of the ozone layer. Growth in international trade and travel, in combination with population growth, has served to increase the frequency and intensity of health concerns bypassing or spilling over sovereign boundaries. Although health has traditionally been seen an area of limited multilateral cooperation, there is growing awareness that contemporary globalization has led to the proliferation of cross border determinants of health status and is undermining the capacity of nation states to protect health through domestic action alone.
Effects of short-term glucocorticoid treatment on changes in cartilage matrix degradation and chondrocyte gene expression induced by mechanical injury and inflammatory cytokines

Traumatic joint injury damages cartilage and causes adjacent joint tissues to release inflammatory cytokines, increasing the risk of developing osteoarthritis. The main objective of this study was to determine whether the combined catabolic effects of mechanical injury, tumor necrosis factor alpha (TNFα) and interleukin-6 (IL-6)/soluble IL-6 receptor (sIL-6R) on cartilage could be abolished by short-term treatment with glucocorticoids such as dexamethasone. In an initial dexamethasone-dose-response study, bovine cartilage explants were treated with TNFα and increasing concentrations of dexamethasone. Bovine and human cartilage explants were then subjected to individual and combined treatments with TNFα, IL-6/sIL-6R and injury in the presence or absence of dexamethasone. Treatment effects were assessed by measuring glycosaminoglycans (GAG) release to the medium and synthesis of proteoglycans. Additional experiments tested whether pre-exposure of cartilage to dexamethasone could prevent GAG loss and inhibition of biosynthesis induced by cytokines, and whether post-treatment with dexamethasone could diminish the effects of pre-established cytokine insult. Messenger ribonucleic acid (mRNA) levels for genes involved in cartilage homeostasis (proteases, matrix molecules, cytokines, growth and transcription factors) were measured in explants subjected to combined treatments with injury, TNFα and dexamethasone. To investigate mechanisms associated with dexamethasone regulation of chondrocyte metabolic response, glucocorticoid receptor (GR) antagonist (RU486) and proprotein convertase inhibitor (RVKR-CMK) were used. Dexamethasone dose-dependently inhibited GAG loss and the reduction in biosynthesis caused by TNFα. The combination of mechanical injury, TNFα and IL-6/sIL-6R caused the most severe GAG loss; dexamethasone reduced this GAG loss to control levels in bovine and human cartilage. Additionally, dexamethasone pre-treatment or post-treatment of bovine explants lowered GAG loss and increased proteoglycan synthesis in cartilage explants exposed to TNFα. Dexamethasone did not down-regulate aggrecanase mRNA levels. Post-transcriptional regulation by dexamethasone of other genes associated with responses to injury and cytokines was noted. GR antagonist reversed the effect of dexamethasone on sulfate incorporation. RVKR-CMK significantly reduced GAG loss caused by TNFα + IL-6 + injury. Short-term glucocorticoid treatment effectively abolished the catabolic effects exerted by the combination of pro-inflammatory cytokines and mechanical injury: dexamethasone prevented proteoglycan degradation and restored biosynthesis. Dexamethasone appears to regulate the catabolic response of chondrocytes post-transcriptionally, since the abundance of transcripts encoding aggrecanases was still elevated in the presence of dexamethasone.