cssi/SciSciGPT-SciSciNet huggingface dataset:
On the parameterized complexity of some optimization problems related to multiple-interval graphs

We show that for any constant t ≥ 2, k-INDEPENDENT SET and k-DOMINATING SET in t-track interval graphs are W[1]-hard. This settles an open question recently raised by Fellows, Hermelin, Rosamond, and Vialette. We also give an FPT algorithm for k-CLIQUE in t-interval graphs, parameterized by both k and t, with running time max{tO(k), 2O(k log k)} ċ poly(n), where n is the number of vertices in the graph. This slightly improves the previous FPT algorithm by Fellows, Hermelin, Rosamond, and Vialette. Finally, we use the W[1]-hardness of k-INDEPENDENT SET in t-track interval graphs to obtain the first parameterized intractability result for a recent bioinformatics problem called MAXIMAL STRIP RECOVERY (MSR). We show that MSR-d is W[1]-hard for any constant d ≥ 4 when the parameter is either the total length of the strips, or the total number of adjacencies in the strips, or the number of strips in the optimal solution.
Mirrors and Phases of N=4 in D=3

3d mirror symmetry for was first proposed in [1] as a duality between certain pairs of generally different 3d N=4 theories at the infrared limit. Infinite sequences of new mirror pairs and strong field theoretic evidence for them were found in [2]. It is a nonperturbative duality that in particular equates certain quantities receiving large quantum corrections with some that are determined entirely classically. Naturally one asks whether this can be the consequence of some string dualities. There are several different approaches [1, 2, 3, 4, 5, 6, 7], each of which has it own advantage and is related to the others by some sequences of dualities. In this talk I will review one that is particularly intuitive [4, 5]. The global R-symmetry of N=4 theories appears as geometric rotations; R-symmetry breaking part of the moduli space of vacua and the parameters of the field theory are realized as the moduli space of D-branes configurations; mirror symmetry itself is implemented by the S duality of type IIB string theory [4]. This construction allows us to engineer a large class of theories and find their mirror duals [5]. Since then it has been generalized to 3d N=2 theories [8, 9]. Similar ideas of constructing field theories in 4d, reviewed in Eguchi’s lecture at this school [10], have also been very fruitful1. In this talk, I will focus on 3d N=4 theories. After reviewing the rules for “model building” via “brane engineering,” I will show how the mirror pairs emerge from this prescription. As an unexpected reward we can predict an infinite number of 3d field theories without conventional Lagrangian descriptions. Some of them are dual to ordinary Lagrangian theories via mirror symmetry, but the rest are not; yet they can be smoothly connected in the moduli space of brane configurations.
Graph expansion analysis for communication costs of fast rectangular matrix multiplication

Graph expansion analysis of computational DAGs is useful for obtaining communication cost lower bounds where previous methods, such as geometric embedding, are not applicable. This has recently been demonstrated for Strassen's and Strassen-like fast square matrix multiplication algorithms. Here we extend the expansion analysis approach to fast algorithms for rectangular matrix multiplication, obtaining a new class of communication cost lower bounds. These apply, for example to the algorithms of Bini et al. (1979) and the algorithms of Hopcroft and Kerr (1971). Some of our bounds are proved to be optimal.
A Sonographic Assessment of Different Patterns of Placenta Previa “Migration” in the Third Trimester of Pregnancy

Objective. The purpose of this study was to compare the rates and patterns of placental “migration” with the mode of fetal and placental delivery and the incidence of peripartum complications. Methods. This was a retrospective study of 163 cases of placenta previa diagnosed by transvaginal sonography at 28 weeks’ gestation that were followed serially by sonography. The patients were stratified into 3 groups depending on the placenta-to-internal cervical os distance: (1) an overlap of 0.0 cm or greater over the cervical os, (2) 0.1 to 2.9 cm, and (3) 3.0 cm or greater. The mean rate of placental migration (millimeters per week) was obtained at 28 to 32 and 32 to 36 weeks’ gestation. A pattern of placental migration was classified as one with acceleration or deceleration of the placental migration in the late third trimester based on a comparison between the migration rates at 28 to 32 and 32 to 36 weeks’ gestation. Results. At the time of delivery, 22, 29, and 112 patients were included in groups 1, 2, and 3, respectively. The rates of placental migration correlated with the final placental distance from the internal cervical os (0.1 to 4.1 mm/wk for groups 1 and 3, respectively). Significantly higher rates of interventional cesarean delivery (CD) (P = .0002), elective CD (P = .0254), manual placenta removal (P = .0419), and placenta accreta (P = .0039), but not CD for indications other than placenta previa (P = .0752), were associated with a placental distance of less than 2.0 cm away from the cervix and a deceleration pattern of placental migration. In contrast, vaginal delivery was significantly associated with a placental distance of 2.0 cm or greater away from the cervix and an acceleration pattern of placental migration (P = .0034). Conclusions. A final placental distance of less than 2.0 cm from the internal cervical os and a deceleration pattern of placental migration were significantly associated with an interventional CD and a higher rate of peripartum complications. Key words: mode of delivery; placenta previa; rate of migration; sonography.
The Faculty Time Divide

This uniquely interdisciplinary study offers a provocative, contemporary look at the ‘Woman Question’ in relation to higher education at the dawn of the twenty-first century. Leading feminist scholars from a wide variety of perspectives and disciplines — including history, philosophy, education, psychology, sociology, and economics — evaluate the role of biology, discrimination, and choice in rationalizing women’s exclusion from fully participating in the process of knowledge production, as well as examining institutional impediments. Contextualizing arguments against women’s inclusion and including contemporary perspectives on gender, this book offers a rich, multi-layered examination and critical insights into understanding the near universal difficulties that women encounter as they seek to participate fully in the process of knowledge production.
Measurement of HQET Parameters and CKM Matrix Elements

The determination of CKM matrix elements in the b‐sector is discussed, emphasizing the new measurements of |Vub| and |Vcb| by the CLEO collaboration.
On the NP-completeness of finding an optimal strategy in games with common payoffs

Consider a very simple class of (finite) games: after an initial move by nature, each player makes one move. Moreover, the players have common interests: at each node, all the players get the same payoff. We show that the problem of determining whether there exists a joint strategy where each player has an expected payoff of at least r is NP-complete as a function of the number of nodes in the extensive-form representation of the game.
On the Carroll–Chen Model

I argue that the Carroll–Chen cosmogonic model does not provide a plausible scientific explanation of the past hypothesis (the thesis that our universe began in an extremely low-entropy state). I suggest that this counts as a welcomed result for those who adopt a Mill–Ramsey–Lewis best systems account of laws and maintain that the past hypothesis is a brute fact that is a non-dynamical law.
Measurement of the insertion loss of a single microbend

An experiment is reported that demonstrates the ability of the optical-time-domain reflector (OTDR) to locate and characterize small waveguide perturbations. Single microbends, as small as 10 microm in amplitude, were located and characterized. The experiment indicates a potential new application for the OTDR characterization of waveguide perturbations.
On the Unification of Dwarf and Giant Elliptical Galaxies

The near orthogonal distributions of dwarf elliptical (dE) and giant elliptical (E) galaxies in the µ e −M and µ e −log R e diagrams have been interpreted as evidence for two distinct galaxy formation processes. However, continuous, linear relationships across the alleged dE/E boundary at M B = −18 mag — such as the relationships between central surface brightness (µ 0) and: a) galaxy magnitude (M); and b) light-profile shape (n) — suggest a similar initial formation mechanism. Here we explain how these latter two trends in fact necessitate a different behavior for dE and E galaxies, exactly as observed, in diagrams involving µ e (and also e). Together with other linear trends across the alleged dE/E boundary, such as those between luminosity and color, metallicity, and velocity dispersion, it appears that the dEs form a continuous extension to the E galaxies. The presence of partially depleted cores in luminous (M B < −20.5 mag) Es does however signify the action of a different physical process at the centers (<~300 pc) of these galaxies.
Open APIs for embedded security

Embedded computer control is increasingly common in appliances, vehicles, communication devices, medical instruments, and many other systems. Some embedded computer systems enable users to obtain their own programs from parties other than the maker of the device. For instance, PDAs and some cell phones offer an open application programming interface that enables users to better customize devices to their needs and support an industry of independent software vendors. This kind of flexibility will be more difficult for other kinds of embedded devices where safety and security are a greater risk. This paper discusses some of the challenges and architectural options for open APIs for embedded systems. These issues are illustrated through an approach to implementing secure programmable payment cards.
Failure of the Overgown to Prevent Nosocomial Infection in a Pediatric Intensive Care Unit

In a pediatric intensive care unit we conducted a 1-year prospective study of 454 patients to determine whether wearing a gown decreased the overall nosocomial infection rate, incidence of intravascular catheter colonization, breaks in handwashing technique, and traffic. The overall infection rate was 26 (13%) of 198 admissions during the gown-wearing periods v 23 (9%) of 256 admissions for the periods when gowns were not worn (P less than .25). Of 348 intravascular catheter tips cultured 16 (4.6%) were colonized during gown-wearing periods compared with 21 (6.3%) of 330 when no gowns were worn (P less than .25). Of 78 patient contacts 54 (69%) were followed by no handwashing during gown-wearing periods and 59 (70%) of 84 contacts were followed by no handwashing during periods when no gowns were worn. The mean occurrence of visits per patient per hour and total visits per hour differed between gown-wearing and no-gown-wearing periods by analysis of variance, P less than .01 and P less than .005, respectively. Although traffic was decreased during periods of gown use, overgowns are an expensive, ineffective method of decreasing nosocomial infection rates, vascular catheter colonization rates, and breaks in handwashing technique.
Beginning With a Baseline: Insuring Productive Technology Integration in Teacher Education

If colleges of education are going to successfully prepare teacher candidates to meet NETS-T standards (Kelly, 2002), then teacher education programs must begin developing strategies to assess technology competencies of beginning college students. Colleges must then move beyond these assessments to providing student support for achieving technological competencies. With this type of foundation, teacher preparation programs will then be able to provide students with experiences that nurture powerful technology integration in P-12 settings. This article presents one college’s efforts in developing and implementing a mandatory technology skills assessment for beginning teacher education students. A sample of the assessment is provided, as well as scoring checklists, a description of the resources that support student mastery of these skills, and the procedures for administering the assessment, and recording results. The context of continued technology integration in coursework and field experiences is emphasized.
Constructive mathematics as a programming logic I: some principles of theory

The design of a programming system is guided by certain beliefs, principles and practical constraints. These considerations are not always manifest from the rules defining the system. In this paper the author discusses some of the principles which have guided the design of the programming logics built at Cornell in the last decade. Most of the necessarily brief discussion concerns type theory with stress on the concepts of function space and quotient types.
Progress toward a soft X-ray FEL☆

Abstract We review the FEL physics and obtain scaling laws for the extension of its operation to the soft X-ray region. We also discuss the properties of an electron beam needed to drive such an FEL, and the present state of the art for the beam production.
Management of Intersexuality: Guidelines for Dealing With Persons With Ambiguous Genitalia

Following the publication of our article about a classic case of sex reassignment,1the media attention was rapid and widespread,2-4as was the reaction of many clinicians. Some wanted to comment or ask questions, but many contacted us directly or indirectly, asking for specific guidelines on how to manage cases of traumatized or ambiguous genitalia.5 Below we offer our suggestions. We first, however, add this caveat: these recommendations are based on our experiences, the input of some trusted colleagues, the comments of intersexed persons of various origins, and the best interpretation of our reading of the literature. Some of these suggestions are contrary to today's common management procedures. We believe, however, that many of those procedures should be modified. These guidelines are not offered lightly. We anticipate that time and experience will dictate that some aspects be changed and such revisions will improve the next set of
Ethnic differences: word descriptors used by African-American and white asthma patients during induced bronchoconstriction.

Study objectives To determine if African-American and white patients with asthma (1) differ in the words they use to describe their breathlessness, and (2) differ in their perception of breathlessness. Design Descriptive cross-sectional design. Setting and participants The study setting was located in Northern California, an ethnically and economically diverse area. A total of 32 subjects, 16 per group, completed the study. Measurements All had a provocation concentration of methacholine chloride causing a 30% fall in FEV 1 (PC 30 ) of ≤ 8 mg/mL. Serial pulmonary function testing was performed. Breathlessness was measured using the Borg scale and the visual analog scale. Word descriptors were measured by an open-ended word descriptor questionnaire. Results Significant ethnic differences in the words used to describe the sensation of breathlessness were present at PC 30 . African Americans used upper airway word descriptors: tight throat (p scared-agitated (p voice tight (p itchy throat (p tough breath (p deep breath (p lightheaded (p out of air (p aware of breathing (p hurts to breathe (p 30 (p Conclusion This study provides valuable new information about ethnicity and the words used to describe breathlessness during airflow obstruction. Asthmatic African Americans used primarily upper airway word descriptors; whites used lower airway or chest-wall word descriptors. Effective symptom monitoring requires asking the correct question and awareness that ethnic differences in the words used to describe breathlessness may exist.
Tube hydroforming: state-of-the-art and future trends

Abstract With the availability of advanced machine designs and controls, tube hydroforming has become an economic alternative to various stamping processes. The technology is relatively new so that there is no large “knowledge base” to assist the product and process designers. This paper reviews the fundamentals of tube hydroforming technology and discusses how various parameters, such as tube material properties, pre-form geometry, lubrication and process control affect product design and quality. In addition, relations between process variables and achievable part geometry are discussed. Finally, using examples, the status of the current technology and critical issues for future development are reviewed.
Practice guideline for evaluation of Fever and infection in long-term care facilities.

The elderly population (i.e., persons aged > or = 65 years) in the United States is rapidly expanding and will nearly double in number over the next 30 years. It is estimated that >40% of persons aged > or = 65 years will require care in a long-term care facility (LTCF), such as a skilled nursing facility (SNF), at some point during their lifetime. For the most part, residents of LTCFs are very old and have age-related immunologic changes, chronic cognitive and/or physical impairments, and diseases that alter host resistance; therefore, they are highly susceptible to infections and their complications. The diagnosis of infections in residents of LTCFs is often difficult because LTCFs differ from acute-care facilities in their goals of care, staffing ratios, types of primary care providers, availability of laboratory tests, and criteria for infections. Consequently, guidelines and standards of practice used for diagnosis of infections in patients in acute-care facilities may not be applicable nor appropriate for residents in LTCFs. Moreover, the clinical manifestations of diseases and infections are often subtle, atypical, or nonexistent in the very old. Fever may be low or absent in LTCF residents with infection. The initial evaluation of an LTCF resident suspected of an infection may not be done by a physician. Although nurses commonly perform initial assessments for infection in residents of LTCFs, further studies are needed to determine the appropriateness and validity of this practice. Provided there are no directives (advance or current by resident or caregiver) limiting diagnostic or therapeutic interventions, all residents of LTCFs with suspected symptomatic infection should have appropriate diagnostic laboratory studies done promptly, and the findings should be discussed with the primary care clinician (see Recommendations). The most common infections among LTCF residents are urinary tract infections, respiratory infections, skin or soft tissue infections, and gastroenteritis. Decisions concerning possible transfer of an LTCF resident to an acute-care facility are best expressed through an advance directive or, when not available, through transfer policies developed by the LTCF. In general, LTCF residents have been transferred to an acute-care facility when any of the following conditions exist: (1) the resident is clinically unstable and the resident or family goals indicate aggressive interventions should be initiated, (2) critical diagnostic tests are not available in the LTCF, (3) necessary therapy or the mode of administration of therapy (frequency or monitoring) are beyond the capacity of the LTCF, (4) comfort measures cannot be assured in the LTCF, and (5) specific infection-control measures are not available in the LTCF.
Quasiparticle energies, excitonic effects and optical absorption spectra of small-diameter single-walled carbon nanotubes

We present a first-principles study of the effects of many-electron interactions on the optical properties of single-walled carbon nanotubes. Motivated by recent experiments, we have carried out ab initio calculations on the single-walled carbon nanotubes (3, 3), (5, 0) and (8, 0). The calculations are based on a many-body Green’s function approach in which both the quasiparticle (single-particle) excitation spectrum and the optical (electron–hole excitation) spectrum are determined. We show that the optical spectrum of both the semiconducting and metallic nanotubes studied exhibits important excitonic effects due to their quasi-one-dimensional nature. Binding energies for excitonic states range from zero for the metallic (5, 0) tube to nearly 1 eV for the semiconducting (8, 0) tube. Moreover, the metallic (3, 3) tube possesses exciton states bound by nearly 100 meV. Our calculated spectra explain quantitatively the observed features found in the measured spectra.
Testing the chiral behavior of the hadron spectrum

We analyze the chiral behavior of the hadron spectrum obtained with quenched Wilson fermions on 170 323 × 64 lattices at β = 6.0. We calculate masses of hadrons composed of both degenerate and non-degenerate quarks. We reduce the statistical errors in mass splittings by directly fitting to the ratio of correlation functions. We find significant deviations from a linear dependence on the quark mass, deviations that are consistent with the higher order terms predicted by quenched chiral perturbation theory. Including these corrections yields splittings in the baryon octet that agree with those observed experimentally. Smaller higher order terms are also present in mρ and mN. By contrast, the decuplet baryons are well described by a linear mass term. We find the decuplet splittings to be 30% smaller than experiment. We extrapolate our data to a → 0 by combining with the GF11 results, and the best fit suggests that the quenched approximation is only good to 10 – 15%.
Graphics-Based Learning in First-Year Computer Science

This paper proposes a method for teaching a first-year course in computer science using graphics-based problems as the teaching medium. Specifically, we present a method for instruction in programming using a semester-long project of developing a ray tracer. This effort is part of a larger project, known as, in which a broad range of undergraduate courses are taught using computer graphics as the motivating application. An overview of this project is provided, along with description and results from the first trial CS2 course instructed using this technique.
Asymmetric Changes In Stock Prices And Investor Recognition Around Revisions To The S&P 500 Index

This study finds that first-time additions to the SP however, companies upgraded from lesser-known S&P indices, reentering the S&P 500, or dropped from the index experience temporary price changes. These price patterns can be explained by changes in investor recognition.
H particle searches at Brookhaven

Abstract Following the suggestion by R. L. Jaffe twenty years ago [1], researchers have been trying to establish the existence of a six-quark object, termed the “H” dibaryon, predicted by the phenomenological quark bag model. This object quickly became the focus of experimental searches at several locations, including the AGS [2]. This search still continues, with perhaps the most active program being carried out at the 2.0 GeV/c beam line at the BNL-AGS. The research was considerably enhanced by the writing of two notable papers at BNL by Aerts and Dover [3,4], which gave quantitative predictions for H-production cross sections in two very different reaction mechanisms. One of these, the formation of cascade atomic deuterium to form the H by fusion, had been first suggested by P. D. Barnes [5]. The 2.0 GeV/c line [6] at the AGS was specifically designed to provide an adequate kaon flux for double strangeness and charge exchange reactions. It has been used for two H searches, E813 and E836, as well as for several ΛΛ searches, E885 and E906. These four experiments are setting significant limits on H-production. The results of these experiments are discussed, and descriptions of related H searches at Brookhaven are given.
Quadratic mode regression

Abstract Generalizing the mode regression of Lee (1989) with the rectangular kernel (RME), we try a quadratic kernel (QME), smoothing the rectangular kernel. Like RME, QME is the most useful when the dependent variable is truncated. QME is better than RME in that it gives a N 1 2 - consistent estimator and an asymptotic distribution which parallels that of Powell's (1986) symmetrically trimmed least squares (STLS). In general, the symmetry requirement of QME is weaker than that of STLS and stronger than that of RME. Estimation of the covariance matrices of both QME and STLS requires density estimation. But a variation of QME can provide an upper bound of the covariance matrix without the burden of density estimation. The upper bound can be made tight at the cost of computation time.
A symmetry-based approach to zaragozic acid: Synthesis and end-differentiation of an advanced intermediate

Abstract Reported is a novel, symmetry-based strategy for the synthesis of the zaragozic acids. Two enantioselective dihyroxylations are used to set the absolute stereochemistry of a C-2 symmetric intermediate. A sequence of a furan photo-oxidation followed by a diastereoselective dihydroxylation breaks the symmetry and sets two quaternary stereocenters. Finally, a group selective lactonization is used to protect one of two secondary hydroxyls. This accomplishes the critical end-differentiation of this intermediate. An approach to protecting group removal and oxidation is also presented.
Electronic Structure of Rh2S3 and RuS2, Two Very Active Hydrodesulfurization Catalysts

The results of Fenske-Hall band structure calculations for bulk Rh{sub 2}S{sub 3} and RuS{sub 2} and for the (210) and (111) surfaces of RuS{sub 2} are described. Although the crystal structures of the two sulfides are quite different, the electronic structure of bulk Rh{sub 2}S{sub 3}and RuS{sub 2} share several similarities. Unlike MoS{sub 2}, which is also used as a hydrodesulfurization (HDS) catalyst, there is no metal-metal bonding and only negligible metal-sulfur {pi} bonding in both Rh{sub 2}S{sub 3} and RuS{sub 2}. As a result, both sulfides are characterized by a narrow high energy occupied metal t{sub 2g} band localized on the metal. Results of calculations for two-dimensional RuS{sub 2} slabs exposing (210) and (111) surface planes provide a description of the electronic structure of 5-, 4-, and 3-coordinate Ru atoms on these surfaces. Stabilization of part or all of the unoccupied Ru e{sub g} band is observed for these surface atoms, and comparisons between the partial densities of states (DOS) of the surface Ru atoms and the orbital structures of isolated coordinatively unsaturated metal centers aid in the interpretation of the surface results. The electronic environments of the surface Ru atoms are also compared to the electronic environments andmore » reactivities of metal centers found in d{sup 6} transition metal complexes that incorporate thiophenic ligands. These comparisons suggest that if the heterogeneous and homogeneous HDS mechanisms are related, then 3-coordinate surface Ru atoms such as those found on the (111) surface could provide active sites.« less
Mass Spectrometric Studies of Oxides

Current studies at NASA Glenn on oxide thermodynamics are discussed. Previous studies on the vaporization of B2O3 in reducing atmospheres led to inconsistent studies when B was used as a reductant. It is shown that liquid B2O3 does not wet B and a clear phase separation was noted in the Knudsen cell. This problem was solved by using FeB and Fe2B to supply a different and constant activity of B. The thermodynamic data thus derived are compared to quantum chemical composite calculations. A major problem in high temperature mass spectrometry is the determination of accurate ionization cross sections, particularly for molecules. The method of Deutsch and Mark shows promise and some sample calculations are discussed. Finally current studies on the thermodynamics of rare earth silicates are discussed. Here the problems are obtaining a measurable signal from SiO2 vaporization and non-equilibrium vaporization. The use of a Ta reducing agent provides a stronger signal, which is related to silica activity. The Whitman-Motzfeld relation adapted to KEMS measurements is applied to obtain equilibrium pressures.
Solar sail orbit operations at asteroids

The inherent capabilities of solar sails and the fact that they need no onboard supplies of fuel for propul- sion make them well suited for use in long-term, multiple-objective missions. They are especially well suited for the exploration of asteroids, where one spacecraft could rendezvous with a number of aster- oids in succession. The orbital mechanics of solar sail operations about an asteroid, however, have not yet been studied in detail. Building on previous stud- ies that consider the equations of motion, we find both hovering points and orbiting trajectories about various sized asteroids using equations of motion for a solar sail spacecraft. These hovering points are stabilizable using feedback control to sail attitude alone. The orbiting trajectories are stable and offer good coverage of the asteroid surface, although re- strictions on sail acceleration are needed for smaller asteroids.
Variational approach to hard sphere segregation under gravity.

It is demonstrated that the minimization of the free energy functional for hard spheres and hard disks yields the result that excited granular materials under gravity segregate not only in the widely known "Brazil nut" fashion, i.e., with the larger particles rising to the top, but also in reverse "Brazil nut" fashion. Specifically, the local density approximation is used to investigate the crossover between the two types of segregation occurring in the liquid state, and the results are found to agree qualitatively with previously published results of simulation and of a simple model based on condensation.
Test of CAP88-PC's Predicted Concentrations of Tritium in Air at Lawrence Livermore National Laboratory

Based on annual tritium release rates from the five sources of tritium at Lawrence Livermore National Laboratory and the Tritium Research Laboratory at Sandia National Laboratory, the regulatory dispersion and dose model, CAP88-PC, was used to predict tritium concentrations in air at perimeter and offsite air surveillance monitoring locations for 1986 through 2001. These predictions were compared with mean annual measured concentrations, based on biweekly sampling. Deterministic predictions were compared with deterministic observations using predicted-to-observed ratios. In addition, the uncertainty on observations and predictions was assessed: when the uncertainty bounds of the observations overlapped with the uncertainty bounds of the predictions, the predictions were assumed to agree with the observations with high probability. Deterministically, 54% of all predictions were higher than the observations, and 96% fell within a factor of three. Accounting for uncertainty, 75% of all predictions agreed with the observations; 87% of the predictions either matched or exceeded the observations. Predictions equaled or exceeded observations at those sampling locations towards which the wind blows most frequently, except those in the hills. Under-predictions were seen at locations towards which the wind blows infrequently when released tritium was from elevated sources. When a high fraction of tritium was from area (diffuse) sources, predictions matched observations.
The generalized Jacobi equation

The Jacobi equation in pseudo-Riemannian geometry determines the linearized geodesic flow. The linearization ignores the relative velocity of the geodesics. The generalized Jacobi equation takes the relative velocity into account; that is, when the geodesics are neighbouring but their relative velocity is arbitrary the corresponding geodesic deviation equation is the generalized Jacobi equation. The Hamiltonian structure of this nonlinear equation is analysed in this paper. The tidal accelerations for test particles in the field of a plane gravitational wave and the exterior field of a rotating mass are investigated. In the latter case, the existence of an attractor of uniform relative radial motion with speed 2−1/2c ≈ 0.7c is pointed out. The astrophysical implication of this result for the terminal speed of a relativistic jet is briefly explored.
Quarkonium polarization in lepton annihilation

Abstract We investigate the polarization properties of vector quarkonia produced in lepton–antilepton annihilation with special attention to effects due to intermediate Z bosons.
The Host Galaxy of GRB 970508

We present late-time imaging and spectroscopic observations of the optical transient (OT) and host galaxy of GRB 970508. Imaging observations roughly 200 and 300 days after the burst provide unambiguous evidence for the flattening of the light curve. The spectroscopic observations reveal two persistent features that we identify with [O II] λ3727 and [Ne III] λ3869 at a redshift of z=0.835—the same redshift as the absorption system seen when the transient was bright. The OT was coincident with the underlying galaxy to better than 370 mas or a projected radial separation of less than 2.7 kpc. The luminosity of the [O II] line implies a minimum star formation rate of 1 M☉ yr-1. In our assumed cosmology, the implied rest-frame absolute magnitude isMB=-18.55, or LB=0.12 L*. This object, the likely host of GRB 970508, can thus be characterized as an actively star-forming dwarf galaxy. The close spatial connection between this dwarf galaxy and the OT requires that at least some fraction of gamma-ray burst progenitors are not ejected in even the weakest galactic potentials.
Short-pulse SETI

Abstract While most optical SETI experiments are configured to detect nanosecond pulses, the majority of their counterpart radio searches integrate for seconds to minutes, looking for unchanging narrow-band carriers or slowly pulsed modulation. The former approach is suggested as an effective way to stand out against stellar photon noise, while the latter approach is dictated by the dispersive effects of the interstellar medium as well as the high visibility of narrow-band signal components. In this paper, we consider effective signal strategies for those that produce, rather than simply search for, optical and radio beacons—signals that are designed to elicit responses from technological civilizations. By considering the communication problem from the point of view of the transmitters, rather than the receivers, we deduce some likely signal characteristics for beacons, and concommitant new strategies for SETI.
Fair scheduling with tunable latency: a round-robin approach

Weighted fair queueing (WFQ)-based packet scheduling schemes require processing at line speeds for tag computation and tag sorting. This requirement presents a bottleneck for their implementation at high transmission speeds. In this paper, we propose an alternative and lower complexity approach to packet scheduling, based on modifications of the classical round-robin scheduler. Contrary to conventional belief, we show that appropriate modifications of the weighted round-robin (WRR) service discipline can, in fact, provide tight fairness properties and efficient delay guarantees to multiple sessions. Two such modifications are described: 1) list-based round robin, in which the server visits different sessions according to a precomputed list which is designed to obtain the desirable scheduling properties and 2) multiclass round robin, a version of hierarchical round robin with controls designed for good scheduling properties. The schemes considered are compared with well-known WFQ schemes and with deficit round robin (a credit-based WRR), on the basis of desirable properties such as bandwidth guarantees, fairness in excess bandwidth sharing, worst-case fairness, and efficiency of latency (delay guarantee) tuning. The scheduling schemes proposed and analyzed here operate with fixed packet sizes, and hence can be used in applications such as cell scheduling in ATM networks, time-slot scheduling on wireless links as in GPRS air interface, etc. A credit-based extension of the proposed schemes to handle variable packet sizes is also possible.
Vinyl Tris(trimethylsilyl)silanes: Substrates for Hiyama Coupling.

The oxidative treatment of vinyl tris(trimethylsilyl)silanes with hydrogen peroxide in aqueous sodium hydroxide in tetrahydrofuran generates reactive silanol or siloxane species that undergo Pd-catalyzed cross-couplings with aryl, heterocyclic, and alkenyl halides in the presence of Pd(PPh3)4 and tetrabutylammonium fluoride. Hydrogen peroxide and base are necessary for the coupling to occur while activation of the silanes with fluoride is not required. The conjugated and unconjugated tris(trimethylsilyl)silanes serve as good cross-coupling substrates. The (E)-silanes undergo coupling with retention of stereochemistry while coupling of (Z)-silanes occurred with lower stereoselectivity to produce an E/Z mixture of products.
On the inviscid limit of the Navier-Stokes equations

We consider the convergence in the L 2 norm, uniformly in time, of the Navier-Stokes equations with Dirichlet boundary conditions to the Euler equations with slip boundary conditions. We prove that if the Oleinik conditions of no back-flow in the trace of the Euler flow, and of a lower bound for the Navier-Stokes vorticity is assumed in a Kato-like boundary layer, then the inviscid limit holds.
Accelerator mass spectrometry in biomedical research

Abstract Biological effects occur in natural systems at chemical concentrations of parts per billion (1:10 9 ) or less. Affected biomolecules may be separable in only milligram or microgram quantities. Quantification at attomole sensitivity is needed to study these interactions. AMS measures isotope concentrations to parts per 10 13–15 on milligram-sized samples and is ideal for quantifying long-lived radioisotopic labels for tracing biochemical pathways in natural systems. 14 C-AMS has now been coupled to a variety of organic separation and definition technologies. Our primary research investigates pharmacokinetics and genotoxicities of toxins and drugs at very low doses. Human subjects research using AMS includes nutrition, toxicity and elemental balance studies. 3 H, 41 Ca and 26 Al are also traced by AMS for fundamental biochemical kinetic research. Expansion of biomedical AMS awaits further development of biochemical and accelerator technologies designed specifically for these applications.
Inhibition of macrophage- and neutrophil-mediated cytotoxicity by verapamil

Peripheral blood monocyte-derived macrophages and polymorphonuclear leukocytes (PMNs) obtained from normal donors kill tumor cells in vitro. However, if verapamil is added to the macrophages or neutrophil tumor cell suspensions in microgram concentrations (0.1 microgram to 0.1 mg), there is marked inhibition of tumor cell killing. The inhibitory effect for the macrophages resulted from an effect of verapamil on both the effector and target cells. When either the effector cells or target cells were preincubated with verapamil, they became resistant to the effects of the cytotoxic macrophages. Cytotoxicity was also inhibited when 0.1 mg of verapamil was added to the macrophages monolayers either at the time of addition of the tumor cells or 15-30 min after addition of the tumor cells, whereas no inhibition of cytotoxicity occurred when verapamil was added more than 30 min after the initiation of the cytotoxic reaction. For the neutrophils it was observed that the inhibitory activity resulted from an effect of verapamil on the effector cells rather than the target cells. When the effector cells were preincubated with verapamil they became incapable of killing the tumor cells, whereas preincubation of the target cells with verapamil had no effect on their ability to be killed by the neutrophils. Cytotoxicity was also inhibited when 0.1 mg of verapamil was added to the neutrophil monolayers either at the time of addition of the tumor cells or 15-60 min after addition of the tumor cells, whereas no inhibition of cytotoxicity occurred when verapamil was added more than 60 min after the initiation of the cytotoxic reaction.
Free radical chemistry of nucleosides and nucleotides. Ring opening of C4′-radicals

Abstract It is demonstrated that nucleotide C4′ radicals may be generated from a C4′-thiolester on treatment with tributyltin hydride. When the reaction is conducted in benzene at reflux the C4′ radical expels the C3′-phosphate group to give a radical cation. This species undergoes deprotonation to an allylic radical which suffers cleavage of the deoxyribose ring. Similar reactions are observed when the reaction is conducted with tris(trimethylsilyl)silane in place of the stannane. In methanolic benzene the radical cation is trapped by methanol to give a new C4′ radical which is quenched before ring opening. The behavior of C4′ radicals toward ring opening is discussed in terms of the conformations imposed by the substituents at C3′.
Instanton distribution in quenched and full QCD

Abstract In order to optimize cooling as a technique to study the instanton content of the QCD vacuum, we have studied the effects of alternative algorithms, improved actions and boundary conditions on the evolution of single instantons and instanton anti-instanton pairs. Using these results, we have extracted and compared the instanton content of quenched and full QCD.
Neural integrators for decision making: a favorable tradeoff between robustness and sensitivity.

A key step in many perceptual decision tasks is the integration of sensory inputs over time, but a fundamental questions remain about how this is accomplished in neural circuits. One possibility is to balance decay modes of membranes and synapses with recurrent excitation. To allow integration over long timescales, however, this balance must be exceedingly precise. The need for fine tuning can be overcome via a “robust integrator” mechanism in which momentary inputs must be above a preset limit to be registered by the circuit. The degree of this limiting embodies a tradeoff between sensitivity to the input stream and robustness against parameter mistuning. Here, we analyze the consequences of this tradeoff for decision-making performance. For concreteness, we focus on the well-studied random dot motion discrimination task and constrain stimulus parameters by experimental data. We show that mistuning feedback in an integrator circuit decreases decision performance but that the robust integrator mechanism can limit this loss. Intriguingly, even for perfectly tuned circuits with no immediate need for a robustness mechanism, including one often does not impose a substantial penalty for decision-making performance. The implication is that robust integrators may be well suited to subserve the basic function of evidence integration in many cognitive tasks. We develop these ideas using simulations of coupled neural units and the mathematics of sequential analysis.
The structure and dynamics of overturns in stably stratified homogeneous turbulence

Direct numerical simulations of stably stratified homogeneous turbulence, with and without mean shear, are used to investigate the three-dimensional structure, evolution and energetic significance of density overturns. Although the flow conditions are idealized, examination of the full-field simulation data provides insight into flow energetics and mixing which may assist in the interpretation of physical measurements, typically limited to one-dimensional vertical profiles. Overturns, defined here through the density field as contiguous regions of non-zero Thorpe displacement, are initially generated by the stirring action of coherent vortex structures present in the flow and further develop through merging with adjacent overturns. During this growth phase, overturns exhibit irregular spatial structure in unsheared flow and elongated structure with distinct orientation in shear flow. Although most of the available potential energy (APE) and buoyancy flux are associated with stable (non-overturning) regions in the flow, young overturns actively contribute to the flow energetics. In particular, overturn peripheries are sites of high levels of APE, buoyancy flux and diapycnal mixing. A collapse phase may follow the growth phase in the absence of adequately strong mean shear. During this phase, buoyancy gradually assumes control of the overturns and their vertical scale steadily decreases. The energetic significance of the overturns diminishes, although high APE and diapycnal mixing continue to occur near their boundaries. In the final phase of their evolution, overturns contribute negligibly to the energetics. The remaining overturns are characterized by a viscous–buoyant balance which maintains their vertical scale. The overturns eventually vanish due to homogenization of their internal density distribution by diffusion. Activity diagrams, sampled at different points of flow evolution, show significant variation in overturn Reynolds and Froude numbers which may have implications for vertical sampling of a turbulent event.
Influence of a perpendicular magnetic field on the thermal depinning of a single Abrikosov vortex in a superconducting Josephson junction

The prime interest of the present research is to measure the thermal energy needed for depinning a trapped vortex when an external magnetic field is perpendicular to the plane of the junction, and thus there are Meissner currents flowing along the edge of the film. These currents introduce an additional force and the author wishes to study thermal depinning under the influence of this force. These studies are of interest because Nb junctions are used in a wide range of electronic applications. Such junctions are useful, for instance, in superconducting quantum interference devices (SQUIDs) or in vortex-flow transistors because their performance can be enhanced by tuning the parameters of the individual junctions to optimum operation values. Furthermore gated Josephson junctions can be used as Josephson field-effect transistors (JOFETs).
Enantioselective Intramolecular Openings of Oxetanes Catalyzed by(salen)Co(III) Complexes: Access to Enantioenriched Tetrahydrofurans

The catalytic enantioselective intramolecular ring-opening of oxetanes with alcohols is catalyzed by (salen)Co(III) complexes. Either a monomeric or oligomeric catalyst can be used successfully in this transformation, providing 3-substituted tetrahydrofurans in both high yield and enantioselectivity. This methodology extends the range of electrophiles that can be activated toward highly enantioselective addition reactions by (salen)metal catalysts to an important new class.
Viscoelastic Properties of Vascular Endothelial Cells Exposed to Uniaxial Stretch

Vascular endothelial cells (VECs) that line the interior of blood vessels are continually stretched as the vessel walls expand and contract. It is widely accepted that VECs will remodel themselves in response to this mechanical stimuli, leading to changes in cell function. Few studies, however, have analyzed the mechanical properties of these cells under stretch. We hypothesize that uniaxial stretch will cause an anisotropic realignment of actin filaments, and a change in the viscoelastic properties of the cell. To test this hypothesis, VECs were grown on a thin, transparent membrane mounted on a microscope. The membrane was stretched, consequently stretching the cells. Time-lapse sequences of the cells were taken every hour with a time resolution of 10 Hz. The random trajectories of intracellular endogenous particles were tracked using in-house algorithms. Using a novel particle tracking microrheology formulation, that takes into account the anisotropic nature of the cytoplasm, these trajectories were analyzed and the mechanical properties of VECs subjected to various stretching conditions were calculated and compared.
Superbubble Activity in Star-Forming Galaxies

Mechanical feedback from massive stars, primarily from Supernovae, can dominate ISM structuring and phase balance, thereby profoundly affecting galactic evolutionary processes. Our understanding of mechanical feedback is based on the adiabatic, wind-driven bubble model, applied on size scales ranging over three decades. Tests of the model, and our consequent understanding of feedback, are reviewed. While the model is broadly successful, critical unknowns still prevent a comprehensive understanding of the consequences of feedback.