cssi/SciSciGPT-SciSciNet huggingface dataset:
Sampling the mesoscale ocean surface currents with various satellite altimeter configurations

Ten-day composites of maximum cross-correlation (MCC) ocean surface current vectors from 1-km spatial resolution Advanced Very High Resolution Radiometer (AVHRR) 11-/spl mu/m thermal infrared images are used to simulate the ocean surface current retrieval capabilities of three satellite altimeter configurations over a large California coastal region. Ground track positions of the nadir sampling TOPEX/Poseidon (TP; now the Jason-1) satellite altimeters are used to compute the cross-track velocity components from the corresponding optimally interpolated MCC vectors for a ten-day period. Next, the Jason-1-only and the TP plus Jason-1 "tandem mission" sampling are simulated as well as the combination of all available satellite altimeters including European Remote Sensing Satellite 2 and Geosat Follow-On. Finally, we simulate surface current retrievals from the proposed Wide Swath Ocean Altimeter (WSOA), which will have both along- and cross-track velocity components over a spatial swath. Comparisons of vector current fields, their differences, and wavenumber spectra from optimally interpolated maps of the "simulated altimetry velocities" with the corresponding MCC field indicates that (1) the combined coverage from Jason-1 plus TP as well as the combination of all available satellite altimeters results in a better representation of the currents than that of Jason-1 alone and (2) the retrieved currents from the WSOA provide an even greater improvement over the tandem mapping and multiple satellites. It will be possible in the future to regularly map the mesoscale surface currents of the ocean with wide-swath ocean altimeters.
A Dynamic and Stochastic Beta and Its Implications in Global Capital Markets

This article investigates the dynamic and stochastic behaviour of the beta coefficient of the one-factor international capital asset pricing model (ICAPM), and its implications for the pricing of stock markets at the country level and the forecasting of stock returns in global stock markets. We apply several novel econometric techniques and conduct necessary statistical tests. We find that the ICAPM has a stochastic and dynamic beta coefficient and that the global stock market is efficient and integrated, and the world market portfolio is mean-variance efficient. We demonstrate that the dynamic and stochastic behaviour of country betas for the developed countries differs from that of developing economies. The empirical results indicate that the trend and the unexpected change of the foreign exchange rate contribute significantly to the variation patterns of country betas, and that explicit consideration of such changing characteristics will serve to increase the accuracy of stock return forecasts in global stock markets.
Mechanisms and models of somatic cell reprogramming

Conversion of somatic cells to pluripotency by defined factors is a long and complex process that yields embryonic-stem-cell-like cells that vary in their developmental potential. To improve the quality of resulting induced pluripotent stem cells (iPSCs), which is important for potential therapeutic applications, and to address fundamental questions about control of cell identity, molecular mechanisms of the reprogramming process must be understood. Here we discuss recent discoveries regarding the role of reprogramming factors in remodelling the genome, including new insights into the function of MYC, and describe the different phases, markers and emerging models of reprogramming.
Onset of helical order

Abstract Renormalization group methods are used to describe systems which model critical phenomena at the onset of helical order. This onset is marked by a change in the “bare propagator” used in perturbation theory from a k2-dependence to a more general form. We consider systems which in the non-helical region exhibit O simultaneously critical phases. Results are given to first order in an ϵ-expansion. For the isotropic case of k2L dependence and O = 2, we give η to first order in 1/n for d- ⩽ d ⩽ d+ where d+- are upper and lower borderline dimensions.
Nearly-Zero Thermal Expansion Along the Layer-Stacking Axis of ZnSe-Based Inorganic–Organic Hybrid Semiconductor Materials

Zero thermal expansion (ZTE) is a desired but rare material property. Herein we report a unique family of inorganic–organic hybrid semiconductors with general formula [ZnSe(L)0.5] (L = organic diamine) that exhibit nearly-zero thermal expansion along the layer-stacking axis in the temperature range of 5–300 K. The unit cell parameters and crystal structures of [ZnSe(en)0.5], [ZnSe(pda)0.5], [ZnSe(bda)0.5], and [ZnSe(ptda)0.5] (en = ethylenediamine, pda = propanediamine, bda = butanediamine, and ptda = pentanediamine) have been refined by the Rietveld method by using powder samples, and their thermal expansion properties have been analyzed and rationalized on the basis of their crystal structures and symmetry. [ZnSe(ptda)0.5] features a very small negative linear thermal expansion coefficient (–7.8 × 10–7 K–1) that approaches the smallest values reported to date.
Constraining the Collisional Nature of the Dark Matter Through Observations of Gravitational Wakes

We propose to use gravitational wakes as a direct observational probe of the collisional nature of the dark matter. We calculate analytically the structure of a wake generated by the motion of a galaxy in the core of an X-ray cluster for dark matter in the highly collisional and collisionless limits. Although the difference between these limits is most likely too subtle to be detected with weak lensing observations, we show that the two cases can be distinguished through detailed X-ray observations. We also discuss the sizes of subhalos in these limits. Preliminary X-ray data on the motion of NGC 1404 through the Fornax group disfavors fluidlike dark matter but does not exclude scenarios in which the dark matter is weakly collisional.
Nuclear magnetic resonance of mass-limited samples using small RF coils.

Open image in new window Figure Schematic diagram of a typical arrangement used for hyphenating chemical microseparations (e.g. capillary HPLC, CE, or CEC) with microcoil NMR detection
High flux photon beam monitor

Abstract We have designed two photon beam position monitors for use on our X-ray storage ring beamlines. In both designs, a pair of tungsten blades, separated by a predetermined gap, intercepts a small fraction of the incoming beam. Due to photoemission, an electrical signal is generated which is proportional to the amount of beam intercepted. The thermal load deposited in the blade is transferred by a heat pipe to a heat exchanger outside the vacuum chamber. A prototype monitor with gap adjustment capability was fabricated and tested at a UV beamline. The results show that the generated electrical signal is a good measurement of the photon beam position. In the following sections, design features and test results are discussed.
On the Role of the WNH Phase in the Evolution of Very Massive Stars: Enabling the LBV Instability with Feedback

We propose the new designation WNH for luminous Wolf-Rayet (WR) stars of the nitrogen sequence with hydrogen in their spectra. These have been commonly referred to as WNL stars (WN7h, for example), but this new shorthand avoids confusion because there are late-type WN stars without hydrogen and early-type WN stars with hydrogen. Clearly differentiating WNH stars from H-poor WN stars is critical when discussing them as potential progenitors of Type Ib/c supernovae and gamma-ray bursts?the massive WNH stars are not likely Type Ib/c supernova progenitors, and are distinct from core He burning WR stars. We show that masses of WNH stars are systematically higher than for bona fide H-poor WR stars (both WN and WC), with little overlap. Also, hydrogen mass fractions of the most luminous WNH stars are higher than those of luminous blue variables (LBVs). While on the main sequence, a star's mass is reduced due to winds and its luminosity slowly rises, so the star increases its Eddington factor, which in turn strongly increases the mass-loss rate, pushing it even closer to the Eddington limit. Accounting for this feedback, observed properties of WNH stars are a natural and expected outcome for very luminous stars approaching the end of core H burning. Feedback from the strong WNH wind itself plays a similar role, enabling the eruptive instability seen subsequently as an LBV. Altogether, for initial masses above 40-60 -->M?, we find a strong and self-consistent case that luminous WNH stars are pre-LBVs rather than post-LBVs (for lower initial mass, the case is less clear). The steady march toward increased mass-loss rates from feedback also provides a natural explanation for the continuity in observed spectral traits from O3 V to O3 If* to WNH noted previously.
Role of flow shear in enhanced core confinement regimes

The importance of the flow shear in various enhanced confinement regimes is discussed in terms of the turbulence suppression criterion in general toroidal geometry. This criterion is then further generalized to include the poloidal angle dependence of the equilibrium electrostatic potential. The implication of the recently observed in - out asymmetry in the fluctuation behaviour in DIII-D VH-mode is discussed.
A possible x-ray and radio counterpart of the high-energy gamma-ray source 3eg j2227+6122

The identity of the persistent EGRET sources in the Galactic plane is largely a mystery. For one of these, 3EG J2227+6122, our complete census of X-ray and radio sources in its error circle reveals a remarkable superposition of an incomplete radio shell with a flat radio spectrum, and a compact, power-law X-ray source with photon index Gamma = 1.5 and with no obvious optical counterpart. The radio shell is polarized at a level of approx. = 25%. The anomalous properties of the radio source prevent us from deriving a completely satisfactory theory as to its nature. Nevertheless, using data from ROSAT, ASCA, the VLA, and optical imaging and spectroscopy, we argue that the X-ray source may be a young pulsar with an associated wind-blown bubble or bow shock nebula, and an example of the class of radio-quiet pulsars which are hypothesized to comprise the majority of EGRET sources in the Galaxy. The distance to this source can be estimated from its X-ray absorption as 3 kpc. At this distance, the X-ray and gamma-ray luminosities would be approx. = 1.7 x 10(exp 33) and approx. = 3.7 x 10(exp 35) erg/s, respectively, which would require an energetic pulsar to power them. If, on the contrary, this X-ray source is not the counterpart of 3EG J2227+6122, then by process of elimination the X-ray luminosity of the latter must be less than 10(exp -4) of its gamma-ray luminosity, a condition not satisfied by any established class of gamma-ray source counterpart. This would require the existence of at least a quantitatively new type of EGRET source, as has been suggested in studies of other EGRET fields.
Can Composite Fluffy Dust Particles Solve the Interstellar Carbon Crisis

Recent observations suggest that the abundance of carbon in the interstellar medium is only ~60% of its solar value, and that other heavy elements may be depleted by a similar amount. Furthermore, more than half of the interstellar carbon is observed to be in the gas in the form of C+, leaving less than ~40% of the solar carbon abundance available for the dust phase. These observations have created the so-called interstellar "carbon crisis," since traditional interstellar dust models require about twice that value to be tied up in graphite grains in order to explain the interstellar extinction curve. Recently, in 1996, J. S. Mathis suggested a possible solution to this crisis. In his newly proposed dust model, the majority of the interstellar carbon is contained in composite and fluffy grains that are made up of silicates and amorphous carbon grains, with 45% of their volume consisting of vacuum. Per unit mass, these grains produce more UV extinction and therefore can account for the interstellar extinction curve with about half the carbon required in traditional dust models. This paper presents a detailed assessment of the newly proposed dust model and concludes that it falls short in solving the carbon crisis, and in providing a fit to the UV-optical interstellar extinction curve. It also predicts a far-infrared emissivity in excess of that observed with the COBE/DIRBE and FIRAS instruments from the diffuse interstellar medium. This excess infrared emission is a direct consequence of the lower albedo of the composite fluffy dust particles, compared with that of the traditional Mathis, Rumpl, & Nordsieck mixture of bare silicate and graphite grains. The failure of the new model highlights the interrelationships between the various dust properties and their observational consequences, and the need to satisfy them all simultaneously in any comprehensive interstellar dust model. In light of these problems, this paper examines other possible solutions to the carbon crisis.
Laryngeal diversion in the treatment of chronic aspiration in children

Chronic aspiration in children can be life-threatening, especially in patients with underlying pulmonary disorders. Numerous surgical procedures have been described to treat chronic aspiration. In patients with severe chronic aspiration, laryngeal diversion is the most effective procedure for reducing soilage of the pulmonary tract. Over a 10-year period at the Children's Hospital of Philadelphia, 14 patients with life-threatening aspiration were managed with a laryngeal diversion. Surgical correction of aspiration resulted in stabilization or improvement of pulmonary function in these patients. The surgical management of chronic aspiration in the pediatric patient is discussed.
The boundary of a boundary principle: A unified approach

The boundary of a boundary principle in field theories is described. The difference in treatment of the principle in electrodynamics and general relativity is pointed out and reformulated in terms of underlying mathematical structure of the theories. The problem of unifying the treatment is formulated and solved. The role of E. Cartan's concept of the moment of rotation associated with the curvature of a Levi-Civita connection on a frame bundle is shown to be crucial for the unification. The analysis of the boundary of a boundary principle in Kaluza-Klein theory is performed and the recipe for a unified treatment of the principle in electrodynamics and general relativity is shown to follow from the analysis. It is pointed out that the unification cand be extended to Yang-Mills fields easily.
Marketing ethics and education: Some empirical findings

This study explores possible links between educational background and ethics among marketing professionals. Data from two surveys of members of the American Marketing Association suggest that marketing professionals with master's degrees and higher are similar to their less educated counterparts in both their ethical standards and their intended ethical behaviors. Marketers with business degrees, however, have lower ethical standards than do graduates of non-business programs, though they report behavior as ethical as that of their non-business educated peers. Business schools may be producing cynics likely to accept marginal behaviors of colleagues though not likely to engage in such behaviors themselves.
The Trade Reducing Effects of Market Power in International Shipping

Abstract Developing countries pay substantially higher transportation costs than developed nations, which leads to less trade and perhaps lower incomes. This paper investigates price discrimination in the shipping industry and the role it plays in determining transportation costs. In the presence of market power, shipping prices depend on the demand characteristics of goods being traded. We show theoretically and estimate empirically that ocean cargo carriers charge higher prices when transporting goods with higher product prices, lower import demand elasticities, and higher tariffs, and when facing fewer competitors on a trade route. These characteristics explain more variation in shipping prices than do conventional proxies such as distance, and significantly contribute to the higher shipping prices facing the developing world. A simple back of the envelope calculation suggests that eliminating market power in shipping would boost trade volumes by 5.9% (for the US) to 15.2% (for Latin America). Our findings are also important for evaluating the impact of tariff liberalization. Cargo carriers decrease shipping prices by 1–2% for every 1% reduction in tariffs.
Overview of radiation hardening for semiconductor detectors

Abstract Semiconductor detectors for high energy physics applications offer the potential to obtain accurate particle spatial resolution and on-line data reduction. A significant disadvantage of semiconductor detectors and their associated circuitry however, is their sensitivity to radiation. Fortunately, a sufficient understanding of radiation effects on semiconductor devices exists that some classes of radiation tolerant semiconductor detectors are possible.
An extended-precision operand computer for integer factoring

We describe an extended-precision operand computer (EPOC). The singleprecision word length is 128 bits. This makes possible calculations with large integers without resort to multiprecision techniques in software. Since this is a specialpurpose machine, the hardware and software have been developed from scratch to implement it. The application toward which the EPOC is directed is the factoring of large integers using the continued fraction algorithm. This application presents interesting mathematical and architectural problems to solve and has implications in cryptography.
Transonic flow calculations over two-dimensional canard-wing systems

As a prototype for the three-dimensional interaction problem, the transonic interference flowfields over twodimensional canard-wing systems are computed using transonic small disturbance theory. In the calculation, the two airfoils comprising the lifting "biplane" system are placed in separate computational planes with an overlapped region across which information from one airfoil to the other is transferred at the end of each relaxation cycle. Results showing the favorable interference in overall lift are presented and compared with linear theory calculations. Far field expressions for solid, slotted, and free jet wind tunnel wall cases that correspond to the canard-wing arrangement are also described.
Separability and one-way functions

We settle all relativized questions of the relationships between the following five propositions: • P=NP. • P=UP. • P=NP ∩ coNP. • All disjoint pairs of NP sets are P-separable. • All disjoint pairs of coNP sets are P-separable. We make the first widespread use of variations of generic oracles to achieve the necessary relativized worlds.
Regio- and Diastereoselective Rhodium-Catalyzed Allylic Substitution with Acyclic α-Alkoxy-Substituted Copper(I) Enolates: Stereodivergent Approach to 2,3,6-Trisubstituted Dihydropyrans

The regio- and diastereoselective transition metal-catalyzed allylic alkylation using α-heteroatom-substituted ketones and carboxylic acid derivatives represents a challenging and important synthetic transformation. We have developed a regio- and diastereoselective rhodium-catalyzed allylic alkylation reaction utilizing the copper(I) enolates derived from alkyl protected acyclic α-alkoxy aryl ketones. This study suggests that the ability to form a chelated enolate intermediate is crucial for obtaining high diastereoselectivity, whereas excellent regioselectivity is obtained regardless of the substituent. Hence, the excellent selectivity coupled with the synthetic utility of α-alkoxy aryl ketone enolates makes this an important new method for the construction of acyclic adjacent ternary stereogenic centers. Finally, the synthetic utility of this protocol was highlighted through the conversion of the aryl ketone to the ester and the development of a stereodivergent approach to 2,3,6-trisubstituted dihydropy...
Pareto, anonymity, and independence: four alternatives

For four alternatives and an even number of individuals, we prove a conjecture in a companion paper: It is impossible for a social choice rule to satisfy all of (1) Pareto, (2) anonymity, (3) full domain, and (4) independence of some alternative, a relaxation of Arrow's IIA.
Document boundary determination using structural and lexical analysis

The document boundary determination problem is the process of identifying individual documents in a stack of papers. In this paper, we report on a classification system for automation of this process. The system employs features based on document structure and lexical content. We also report on experimental results to support the effectiveness of this system.
Sequential pairing of mixed integer inequalities

We investigate a scheme, called pairing, for generating new valid inequalities for mixed integer programs by taking pairwise combinations of existing valid inequalities. The pairing scheme essentially produces a split cut corresponding to a specific disjunction, and can also be derived through the mixed integer rounding procedure. The scheme is in general sequence-dependent and therefore leads to an exponential number of inequalities. For some important cases, we identify combination sequences that lead to a manageable set of non-dominated inequalities. We illustrate the framework for some deterministic and stochastic integer programs and we present computational results showing the efficiency of adding the new generated inequalities as cuts.
Improving the partial-global stochastic metropolis update for dynamical smeared link fermions

Abstract We discuss several methods that improve the partial-global stochastic Metropolis (PGSM) algorithm for smeared link staggered fermions. We present autocorrelation time measurements and argue that this update is feasible even on reasonably large lattices.
Malleus handle: determinant of success in ossiculoplasty.

Abstract Objective The purpose of this study is to identify prognostic factors affecting outcome in ossicular chain reconstruction (OCR). Study design and setting This study is a retrospective case series of electronic database at an academic institution. Materials and methods We reviewed 209 cases of chronic supportive otitis media performed from January 2000 through December 2007 and collected demographic, clinical, audiologic, and outcome information. Univariate analyses of group differences in terms of postoperative air-bone gap (ABG) changes were evaluated by analysis of variance. Multiple regression analyses were used to examine the relationship between postoperative ABG and the independent variables. Results There were 105 cases of OCR the met the inclusion criteria (44 primary and 61 revision tympanoplasties), with an average follow-up of 19 months. The diagnoses were chronic suppurative otitis media without cholesteatoma in 36 cases and cholesteatoma in 69 cases. The mean preoperative ABG was 34 ± 15 dB, and the mean postoperative ABG was 20 ± 14 dB ( P Conclusions Favorable prognostic factors in OCR include smaller preoperative ABG and the presence of an intact malleus handle.
Thermal analysis and test of laser reference cavity

Laser YAG :Nd en appareillage embarque en vol spatial .Les conditions spatiales permettent d'obtenir une stabilite en frequence du laser tres elevee
Optical Motion Control Applied to the Atmospheric Cloud Physics Laboratory (ACPL)

The use of laser radiation pressure for optical motion control (OMC) of spherical water droplets (5-130 /*m radius) is discussed. It is shown that a Gaussian beam can be used to manipulate and stabilize individual particles for studying cloud droplet or ice crystal growth and for investigating collision/coalescence phenomena. In the near-zero-gravity environment of the Atmospheric Cloud Physics Laboratory (ACPL) payload on Shuttle/Spacelab, OMC can provide 1) velocities from <0.01 to 5 cm/s; 2) precise positioning (±5 /*m) of water droplets up to 130 jun; and 3) simulation of l-g conditions (velocity or acceleration) for droplets of up to ~ 13 jim. ACPL experiments benefiting from OMC are also discussed.
NP is as easy as detecting unique solutions

Abstract For every known NP-complete problem, the number of solutions of its instances varies over a large range, from zero to exponentially many. It is therefore natural to ask if the inherent intractability of NP-complete problem is caused by this wide variation. We give a negative answer to this question using the notion of randomized polynomial time reducibility. We show that the problems of distinguishing between instances of SAT having zero or one solution, or of finding solutions to instances of SAT having a unique solution, are as hard as SAT, under randomized reductions. Several corollaries about the difficulty of specific problems follow. For example, computing the parity of the number of solutions of a SAT formula is shown to be NP-hard, and deciding if a SAT formula has a unique solution is shown to be D p -hard, under randomized reduction. Central to the study of cryptography is the question as to whether there exist NP-problems whose instances have solutions that are unique but are hard to find. Our result can be interpreted as strengthening the belief that such problems exist.
QCDSP: The first 64 nodes

Abstract We present a summary of the progress on QCDSP in the last year. QCDSP, Quantum Chromodynamics on Digital Signal Processors, is an inexpensive computer being built at Columbia that can achieve 0.8 teraflops for three million dollars.
Translating the Social Watch Gender Equity Index for University Use.

Although progress has been made, statistics indicate that nearly a half century after the Civil Rights Act of 1964 was passed, gender equity has not yet been achieved in academia. Research indicate...
Kinetically constrained ring-polymer molecular dynamics for non-adiabatic chemical reactions

We extend ring-polymer molecular dynamics (RPMD) to allow for the direct simulation of general, electronically non-adiabatic chemical processes. The kinetically constrained (KC) RPMD method uses the imaginary-time path-integral representation in the set of nuclear coordinates and electronic states to provide continuous equations of motion that describe the quantized, electronically non-adiabatic dynamics of the system. KC-RPMD preserves the favorable properties of the usual RPMD formulation in the position representation, including rigorous detailed balance, time-reversal symmetry, and invariance of reaction rate calculations to the choice of dividing surface. However, the new method overcomes significant shortcomings of position-representation RPMD by enabling the description of non-adiabatic transitions between states associated with general, many-electron wavefunctions and by accurately describing deep-tunneling processes across asymmetric barriers. We demonstrate that KC-RPMD yields excellent numerical results for a range of model systems, including a simple avoided-crossing reaction and condensed-phase electron-transfer reactions across multiple regimes for the electronic coupling and thermodynamic driving force.
General 2+1 dimensional effective actions and soliton spin fractionalization

Abstract We propose actions for non-linear sigma models on cosets G H in 2+1 dimensions that include the most general non-linear realizations of Chern-Simons terms. When G is simply connected and H contains r commuting U(1) factors, there are r different topologically conserved charges and generically r different types of topological solitons. Soliton spin fractionalizes as a function of the Chern-Simons couplings, with independent spins associated to each species of soliton charge, as well as to pairs of different charges. This model of soliton spin fractionalization generalizes to arbitrary G H a model of Wilczek and Zee for one type of soliton.
SIMPLIFICATION OF MATHEMATICAL MODELS OF CHEMICAL REACTION SYSTEMS

Detailed modeling of complex reaction systems is becoming increasingly important in the development, analysis, design, and control of chemical reaction processes. For industrial processes, complete incorporation of the chemistry into process models facilitates the minimization of byproduct and pollutant formation, increased efficiency, and improved product quality. Processes that involve complex reaction networks include a variety of noncatalytic and homogeneous or heterogeneous catalytic processes (such as fluid catalytic cracking, combustion, chemical vapor deposition, and alkylation). For some systems, large sets of relevant reactions have been identified for use in simulations.1-3 For others, the availability of advanced computing environments has enabled the automated generation of reaction networks and their models, based on computational descriptions of the reaction types occurring in the system.4-6 The use of such complex models is hindered by two obstacles. First, because of their sheer size and the presence of multiple time scales, these models are difficult to solve. Second, the models contain large numbers of uncertain (and sometimes unknown) kinetic parameters; regression to determine the parameters of complex nonlinear models is both difficult and unreliable, and the sensitivity of simulations to parameter uncertainties cannot be easily ascertained. Furthermore, for the purpose of gaining insights into the reaction system’s behavior, it is usually preferable to obtain simpler models that bring out the key features and components of the system. For these reasons, model simplification and order reduction are becoming central problems in the study of complex reaction systems. The simulation, monitoring, and control of a complex chemical process benefit from the derivation of accurate and reliable reduced models tailored to particular process modeling tasks. Model simplification is directly linked to identification of key reactions and sets of species that give valuable insights into the behavior of the network and how it may be influenced. Advanced control schemes such as model predictive control7 or multiple model adaptive control8 must be based on selecting appropriate reduced models and tracking key sets of species. Ideally, a model order reduction algorithm should have broad applicability, enable analysis at several levels of detail, and provide an assessment of the modeling error.
Competition between discrete random variables, with applications to occupancy problems

Abstract Consider n players whose “scores” are independent and identically distributed values { X i } i = 1 n from some discrete distribution F. We pay special attention to the cases where (i) F is geometric with parameter p → 0 and (ii) F is uniform on { 1 , 2 , … , N } ; the latter case clearly corresponds to the classical occupancy problem. The quantities of interest to us are, first, the U-statistic W which counts the number of “ties” between pairs i, j; second, the univariate statistic Yr, which counts the number of strict r-way ties between contestants, i.e., episodes of the form X i 1 = X i 2 = ⋯ = X i r ; X j ≠ X i 1 ; j ≠ i 1 , i 2 , … , i r ; and, last but not least, the multivariate vector ZAB=(YA, YA+1,…,YB). We provide Poisson approximations for the distributions of W, Yr and ZAB under some general conditions. New results on the joint distribution of cell counts in the occupancy problem are derived as a corollary.
Thermal expansion of carbon structures

Using an empirical bond-order potential, molecular dynamics (MD) simulations, and lattice dynamics calculations, we study the thermal expansion of diamond, graphite and single-walled carbon nanotubes. MD simulations demonstrate that, while the C-C bond length increases at a similar rate with increasing temperature in all structures, the thermal expansion coefficient varies greatly in a manner consistent with experiment. An analysis of the mode-dependent Gr\"uneisen parameters provides a detailed picture of how structure influences the competition between various vibrational modes associated with negative and positive Gr\"uneisen parameters in determining the overall thermal expansion coefficient.
METHODOLOGIES FOR THE COST-BENEFIT ANALYSIS OF COMPUTER GRAPHICS SYSTEMS

Abstract This paper assesses the state of the art in cost-benefit analyses of computer graphics systems and suggests an approach for developing improved methodology. Cost-benefit analyses are distinguished from analyses of system performance in that the latter is directed at optimizing system performance at a given level of investment, while the former is directed at justifying the investment itself. Computer graphic system design alternatives are first outlined. Then methods of analyzing the performance and costs of computer systems in general and graphic systems in particular are discussed. With this information it is shown how cost-effectiveness analyses may be performed. The next crucial step is to conduct benefit analysis, an ill-defined art. The results of benefit analysis must be combined with cost-effectiveness analysis in order to perform the desired cost-benefit analysis. An experimental methodology is suggested for better performing benefit analyses of computer graphics systems. A more rigorous formulation of the cost-benefit procedure is then outlined. No attempt is made in this report to actually perform such an analysis.
Outflow-driven Cavities: Numerical Simulations of Intermediaries of Protostellar Turbulence

We investigate the evolution of fossil cavities produced by extinct young stellar object (YSO) jets and wide-angle outflows. Fossil cavities are ellipsoidal or cylindrical shells of swept-up ambient (molecular cloud) material moving at low velocities. The cavities form when the momentum in a YSO jet or wide-angle outflow decays in time, allowing the bow shock or swept-up shell to decelerate to velocities near the turbulent speed in the cloud. It has been suggested in previous studies that cavities provide efficient coupling between the jets/outflows and the cloud and, as such, are the agents by which cloud turbulence can be re-energized. In this paper, we carry forward a series of numerical simulations of jets and outflows whose momentum flux decreases in time. We compare simulations with decaying momentum fluxes to those with constant flux. We show that decaying flux models exhibit deceleration of the outflow head and back-filling via expansion off of the cavity walls. They also have lower density contrast and are longer lived and wider than their continuously driven counterparts. The simulations recover the basic properties of observed fossil cavities. In addition, we provide synthetic observations in terms of position-velocity (PV) diagrams, which demonstrate that fossil cavities form both jets and wide-angle outflows and are characterized by linear "Hubble law" expansion patterns superimposed on "spur" patterns, indicative of the head of a bow shock.
New HST Observations of the Halo Gas of NGC 3067: Limits on the Extragalactic Ionizing Background at Low Redshift and the Lyman Continuum Escape Fraction

We present ultraviolet spectroscopy from HST/GHRS and reanalyze existing Hα images of the quasar/galaxy pair 3C 232/NGC 3067 and of the halo gas associated with NGC 3067. The spectra permit measurement of, or limits on, the column densities of Fe I, Fe II, Mg I, and Mg II in the absorbing cloud. Two distinct models of the extragalactic radiation field are considered: (1) the ionizing spectrum is dominated by a power-law extragalactic continuum, and (2) the power-law spectrum contains a Lyman break, implying enhanced flux longward of 912 A relative to the hydrogen-ionizing flux. Models of the second type are required to fully explore the ionization balance of the Fe and Mg in the model cloud. The Hα images constrain the escape fraction of Lyman continuum photons from the galaxy to fesc ≤ 0.02. With the assumption that the cloud is shielded from all galactic contributions, we can constrain the intensity and shape of the extragalactic continuum. For an AGN-dominated power-law extragalactic spectrum, we derive a limit on the extragalactic ionizing flux Φion ≥ 2600 photons cm-2 s-1, or I0 ≥ 10-23 ergs cm-2 s-1 Hz-1 sr-1 for a ν-1.8 ionizing spectrum and a cloud of constant density. When combined with previous upper limits from the absence of Hα recombination emission from intergalactic clouds, our observations require 2600 ≤ Φion ≤ 10,000 photons cm-2 s-1. We show that if galactic contributions to the incident radiation are important, it is difficult to constrain Φion. These results demonstrate that galactic halo opacities and their wavelength dependence are crucial to understanding the abundance of low-ionization metals in the IGM.
Heart Failure: The Hidden Problem of Pain

Although dyspnea and fatigue are hallmark symptoms of heart failure (HF), the burden of pain may be underrecognized. This study assessed pain in HF and identified contributing factors. As part of a multicenter study, 96 veterans with HF (96% male, 67+/-11 years) completed measures of symptoms, pain (Brief Pain Inventory [BPI]), functional status (Functional Morbidity Index), and psychological state (Patient Health Questionnaire-2 and Generalized Anxiety Disorder-2). Single items from the BPI interference and the quality of life-end of life measured social and spiritual well-being. Demographic and clinical variables were obtained by chart audit. Correlation and linear regression models evaluated physical, emotional, social, and spiritual factors associated with pain. Fifty-three (55.2%) HF patients reported pain, with a majority (36 [37.5%]) rating their pain as moderate to severe (pain>or=4/10). The presence of pain was reported more frequently than dyspnea (67 [71.3%] vs. 58 [61.7%]). Age (P=0.02), psychological (depression: P=0.002; anxiety: P=0.001), social (P<0.001), spiritual (P=0.010), and physical (health status: P=0.001; symptom frequency: P=0.000; functional status: P=0.002) well-being were correlated with pain severity. In the resulting model, 38% of the variance in pain severity was explained (P<0.001); interference with relations (P<0.001) and symptom number (P=0.007) contributed to pain severity. The association of physical, psychological, social, and spiritual domains with pain suggests that multidisciplinary interventions are needed to address the complex nature of pain in HF.
MR imaging of lymph nodes in the head and neck

This article reviews imaging-based nodal classification, recent advancements in MR imaging techniques for lymph node imaging, and characteristics of MR imaging for necklymphadenopathy. Further technical development of MR imaging is necessary to improve accuracy of diagnosis of lymph node metastases in patients with no head and neck cancer. Development of new tissue-specific MR contrast agents and functional imaging studies to address biologic activity of lymph nodes is essential in the future.
Robust Control of Self-Adjoint Distributed-Parameter Structures

This paper examines the active vibration control-of distributed-parameter structures in which a self-adjoint differential operator expresses the stiffness distribution. For large and complex structures, computational requirements and/or modeling limitations ensure that a reduced-order controller is used. However, although in practice only discrete actuators and discrete sensors are available, spatially distributed control forces and spatially distributed observations are desirable for implementing a reduced-order controller. Therefore a distinction arises among 1) designing distributed control forces for a reduced-order model, 2) implementing the control forces with a number of actuators, and 3) estimating the distributed state from a number of sensors. Herein the distinctions are realized by introducing three appropriate projection operations. The effects of the three projections on the actual closed-loop eigenvalues are investigated in detail. A criterion for the controller to be robust in the stability sense is discussed and illustrative examples are presented.
Effect of data reduction and fiber-bridging on Mode I delamination characterization of unidirectional composites:

Reliable delamination characterization data for laminated composites are needed for input in analytical models of structures to predict delamination onset and growth. The double-cantilevered beam s...
Continuous Monitoring of Binary Gas Mixture Concentration With Application to Turbine Blade Cooling Experiments

Turbine blade cooling experiments often use mixtures of air and a heavy gas (CO 2 ,S F 6) to simulate coolant/mainstream density ratios. If the mixing of the mainstream with the coolant ejected from the blade is of interest, then it may be necessary to determine the spatial distribution of the heavy gas concentration in the flowfield. Commercial analyzers are too slow and have other disadvantages when used for this purpose. To meet this special need, a device has been developed to monitor the heavy gas concentration continuously in a small sample stream by determining the speed of sound in the sample. Together with the temperature of the sample, the information is sufficient to determine the concentration. The device measures the time of propagation for an ultrasonic burst transverse to the stream. The temperature of the gas contained in the device is controlled and measured. Calibration with several gas mixtures (air and CO 2 ,S F 6 , He) has shown an uncertainty ~Cmeas2Ctrue! of 2 percent over the full concentration range of 0 ‐100 percent for CO2 and SF6 . The device is operable in the pressure range from250 to 100 kPa gage and in the temperature range from 0°C to 40°C. The instrument is rugged and will survive in noisy, turbulent environments.@S0889-504X~00!01202-2#
Metrics of positive Ricci curvature on vector bundles over nilmanifolds

We construct metrics of positive Ricci curvature on some vector bundles over tori (or more generally, over nilmanifolds). This gives rise to the first examples of manifolds with positive Ricci curvature which are homotopy equivalent but not homeomorphic to manifolds of non-negative sectional curvature.
Opportunities for Neutrino Physics at the Spallation Neutron Source (SNS)

In this paper we discuss opportunities for a neutrino program at the Spallation Neutrons Source (SNS) being commissioned at ORNL. Possible investigations can include study of neutrino-nuclear cross sections in the energy range important for supernova dynamics and neutrino nucleosynthesis, a search for neutrino-nucleus coherent scattering, and various tests of the standard model of electro-weak interactions.
Stochastic Properties of Time‐Averaged Financial Data: Explanation and Empirical Demonstration Using Monthly Stock Prices

This article considers the potential statistical problems resulting from the use of averaged rather than end-of-period data in financial research. Averaged data are widely employed throughout the literature without explicit recognition that the use of such data results in biased estimates of the variance, covariance and autocorrelation of the first as well as higher order changes. We illustrate the magnitude of the biases, using the S&P 500 end-of-month series over the period March 1957 to February 2001. Results confirm the predictions of Working and of Schwert. In addition, an analysis of the properties of higher-order lags indicates that the bias persists, a result not previously suggested in the literature. We also find that these statistical biases are time varying-which has significant implications for empirical financial research.
Satellite Laser Altimeter for Measurement of Ice Sheet Topography

We describe the design and expected performance of a spaceborne laser altimeter based on a nadir-oriented laser transmitter, a 0.5-m-diam receiver telescope, and a high-accuracy satellite attitude measurement system. This instrument is designed for high-resolution mapping of polar ice sheet topography where conventional radar altimeters have difficulty. This instrument could also provide useful data on cloud-top heights and the ocean surface.
An experimental investigation of heat transfer from a highly cooled turbulent boundary layer.

Shocktube measurements of turbulent heat transfer in supersonic, dissociated air and in the presence of a zero pressure gradient are presented for incident shock velocities from 3 to 6 mm//zsec and initial driven tube pressures of 5, 8, 10, and 20 mm Hg. These data were obtained using platinum calorimeter gages positioned on the inside surface of a sharp leadingedge hollow cylinder with its axis aligned parallel to the frees tream flow. The range of conditions included Reynolds numbers from approximately 10 to 1.4 X 10, total enthalpies simulating flight velocities up to 8 km/sec, and walltoadiabaticwall enthalpy ratios from 0.01 to 0.04. Two-dimensional roughness elements were used to trip the boundary layer. The data obtained are compared with a number of existing techniques for the prediction of turbulent heating. Although the data was obtained at conditions outside of the range on which the method of Spalding and Chi is based, reasonable agreement with this method is shown to exist. Comparisons of existing methods of prediction are also made with other experimental data available from the literature.
Mechanical aggregation of enstatite chondrites from an inhomogeneous debris cloud

Enstatite chondrites have oxygen isotope ratios closer to those of the earth and moon than other meteorites. Their minerals are chemically reduced; metal contains Si, and some Ca, Ti, Mg and Mn are incorporated in sulphides rather than silicates. Clinoenstatite and olivine are virtually Fe-free. Two types of clinoenstatite in the Indarch enstatite chondrite have been reported, one luminescing blue and one red. Similar clinoenstatites in the Kota-Kota enstatite chondrite are associated with two distinct types of forsteritic olivine, one luminescing orange and the other blue. The textural relations and differences in chemical composition cannot be explained by progressive condensation from the solar nebula and require the mechanical mixing of material from at least two sources. It is suggested here that enstatite chondrites result from mechanical and chemical processes during aerodynamic sorting and gravitational settling of debris from a hot cloud of dust, liquid and gas produced during collision of planetesimals.
Euclidean Group Invariant Computation of Stochastic Completion Fields Using Shiftable-Twistable Functions

We describe a method for computing the likelihood that a completion joining two contour fragments passes through any given position and orientation in the image plane. Like computations in primary visual cortex (and unlike all previous models of contour completion), the output of our computation is invariant under rotations and translations of the input pattern. This is achieved by representing the input, output, and intermediate states of the computation in a basis of shiftable-twistable functions.