cssi/SciSciGPT-SciSciNet huggingface dataset:
Central Retinal Vein Occlusion

In 1855, Liebreich [1] first described the clinical picture of retinal vein occlusion and called it “retinal apoplexy.” Michel [2] established it as a clinical entity resulting from thrombosis in 1878. Duke-Elder and Dobree [3] accurately summarized the state of knowledge on retinal vein occlusion in 1967 when he stated: “Since that time (von Michel’s) the condition has been the subject of almost continuous research but nevertheless, even today, many points both in the aetiology and in the intimate mechanism of the obstruction are still unelucidated.” Later advances, however, have provided a good deal of new information on various aspects of CRVO. The major problem in reviewing the information is that the majority of the reports in the literature have combined all types of retinal vein occlusions in one group, rather than describing information specifically on CRVO separately. I plan to discuss CRVO to provide the latest information on this common, important disease.
Fault tolerant algorithms for a linear array with a reconfigurable pipelined bus system

Recently, researchers have proposed many models using reconfigurable optically pipelined buses. All algorithms developed for these models assume that a healthy system is available. We present some fundamental algorithms that are able to tolerate up to N/2 faults on an N-processor, linear array with a reconfigurable pipelined bus system (LARPBS) (one particular optical model). We then extend these results to apply to other algorithms in the areas of image processing and matrix operations.
Conformal Deformation on Manifolds With Boundary

We consider natural conformal invariants arising from the Gauss–Bonnet formulas on manifolds with boundary, and study conformal deformation problems associated to them.
Anisotropy of Magnetohydrodynamic Turbulence and the Polarized Spectra of OH Masers

We consider astrophysical maser radiation that is created in the presence of mildly supersonic, magnetohydrodynamic (MHD) turbulence. The focus is on the OH masers for which the magnetic field is strong enough that the separations of the Zeeman components are greater than the spectral line breadths. A long-standing puzzle has been the absence of the Zeeman π-components and the high circular polarization in the observed spectra of these masers. We first argue that the elongation of eddies along the field that has recently been recognized in MHD turbulence will enhance the optical depth parallel to the magnetic field in comparison with that perpendicular to the magnetic field. We then simulate maser emission with a numerical model of MHD turbulence to demonstrate quantitatively how the intensities of the linearly polarized π-components are suppressed and the intensities of the nearly circularly polarized σ-components are enhanced. This effect is also generic in the sense that most spectral lines in MHD turbulence with Mach number M ~ 1 should have larger optical depth parallel to the magnetic field than perpendicular. The effect is reduced considerably when M < 1. The simulations also demonstrate that the velocity and magnetic field variations due to the turbulence can (but do not necessarily) cause one of the σ-components to be much more intense than the other, as is often observed for mainline OH masers.
A method for evaluating and selecting field experiment locations

When marketing researchers perform field experiments, it is crucial that the experimental location and the control location are comparable. At present, it is difficult to assess the comparability of field locations because there is no way to distinguish differences between locations that are due to random versus systematic factors. To accomplish this, we propose a methodology that enables field researchers to evaluate and select optimal field locations by parsing these random versus systematic effects. To determine the accuracy of our proposed methodology, we performed computer simulations with 10,000 cases per simulation. The simulations demonstrate that accuracy increases as the number of data points increases and as consistency increases.
Higgs bundles and holomorphic forms

Abstract For a complex manifold X which has a holomorphic form ϖ of odd degree k , we endow Ea=⊕p≥aΛ(p,0)(X) with a Higgs bundle structure θ given by θ(Z)(φ):={i(Z)ϖ}∧φ . The properties such as curvature and stability of these and other Higgs bundles are examined. We prove (Theorem 2, Section 2, for k>1 )Ea and additional classes of Higgs subbundles of Ea do not admit Higgs–Hermitian–Yang–Mills metric in any one of the cases: (i) deg (X) , (ii) deg (X)=0 and a≤n−k+1 , or (iii) a≤n−k+1 and k⩾ 1 2 n+1 . We give examples of (noncompact) Kahler manifolds with the above Higgs structure which admit Higgs–Hermitian–Yang–Mills metrics. We also examine vanishing theorems for (p,q) -forms with values in Higgs bundles.
Critical exponent for the density of percolating flux

This paper is a study of some of the critical properties of a simple model for flux. The model is motivated by SU(2) gauge theory at nonzero temperature and is equivalent to the Ising model in three dimensions. The phase with condensed flux is studied. This is the ordered phase of the Ising model and the high temperature, deconfined phase of the gauge theory. The flux picture will be used in this phase. Near the transition, the density of flux is low enough so that flux variables remain useful. There is a finite density of finite flux clusters on both sides of the phase transition. In the deconfined phase, there is also an infinite, percolating network of flux with a density that vanishes as {ital T}{r_arrow}{ital T}{sub {ital c}}{sup +}. On both sides of the critical point, the nonanalyticity in the total flux density is characterized by the exponent (1{minus}{alpha}). The main result of this paper is a calculation of the critical exponent for the percolating network. The exponent for the density of the percolating cluster is {zeta}=(1{minus}{alpha}){minus}({ital cphi}{minus}1). The specific heat exponent {alpha} and the crossover exponent {ital cphi} can be computed in the {epsilon} expansion. Since {zeta}{lt}(1{minus}{alpha}), themore » variation in the separate densities is much more rapid than that of the total. Flux is moving from the infinite cluster to the finite clusters much more rapidly than the total density is decreasing.« less
Hyperfine Structure Identification of Interstellar Cyanoallene toward TMC-1

Interstellar cyanoallene (CH2CCHCN) has been detected with the 100 m Green Bank Telescope (GBT) toward the dark Taurus molecular cloud (TMC-1) by means of the 414-313, 404-303, 515-414, and 505-404 rotational transitions at 20.2, 20.6, 25.2, and 25.7 GHz, respectively. The hyperfine structure (hfs) of the 414-313 transition is resolved; the remaining transitions have hfs components that are blended but are inferred owing to line width excesses atypical of TMC-1. An analysis of these four rotational transitions yields an average column density NT = 2.0(5) × 1012 cm-2 at an assumed rotational temperature of 4 K. The cyanoallene isomer methylcyanoacetylene (CH3CCCN) has previously been observed in TMC-1 and found to have a rotational temperature of ~4 K by other investigators. Using the GBT, the K = 0 and K = 1 structure of the JK = 5K-4K transition of methylcyanoacetylene was resolved toward TMC-1 and a total column density of NT = 4.5(4) × 1011 cm-2 was obtained for the 4 K rotational temperature. Thus, cyanoallene appears to be more abundant than methylcyanoacetylene toward TMC-1 by a factor of ~4.5. The implications of this result are discussed in terms of relative bonding energy differences and possible differences in formation chemistry.
Semi-definite relaxations for minimum bandwidth and other vertex-ordering problems

We present simple semi-definite programming relaxations for the NP-hard minimum bandwidth and minimum length linear ordering problems. We then show how these relaxations can be rounded in a natural way (via random projection) to obtain approximation guarantees for both of these vertex-ordering problems.
On eigenvalues of a Rayleigh quotient matrix

This note deals with the following problem: Let A be an n × nHermitian matrix, and Q and Q be two n × m (n>m⩾1) matricesboth with orthonormal column vectors. How do the eigenvalues of the m × m Hermitian matrix QHAQ differ from those of the m × m Hermitian matrix QHAQ? We give a positive answer to one of the unsolved problems raised recently by Sun.
A Stealth Supersymmetry Sampler

The LHC has strongly constrained models of supersymmetry with traditional missing energy signatures. We present a variety of models that realize the concept of Stealth Supersymmetry, i.e. models with R-parity in which one or more nearly-supersymmetric particles (a “stealth sector”) lead to collider signatures with only a small amount of missing energy. The simplest realization involves low-scale supersymmetry breaking, with an R-odd particle decaying to its superpartner and a soft gravitino. We clarify the stealth mechanism and its differences from compressed supersymmetry and explain the requirements for stealth models with high-scale supersymmetry breaking, in which the soft invisible particle is not a gravitino. We also discuss new and distinctive classes of stealth models that couple through a baryon portal or Z′ gauge interactions. Finally, we present updated limits on stealth supersymmetry in light of current LHC searches.
How Much Is a Reduction of Your Customers' Wait Worth? An Empirical Study of the Fast-Food Drive-Thru Industry Based on Structural Estimation Methods

In many service industries, companies compete with each other on the basis of the waiting time their customers experience, along with other strategic instruments such as the price they charge for their service. The objective of this paper is to conduct an empirical study of an important industry to measure to what extent waiting time performance impacts different firms' market shares and price decisions. We report on a large-scale empirical industrial organization study in which the demand equations for fast-food drive-thru restaurants in Cook County are estimated based on so-called structural estimation methods. Our results confirm the belief expressed by industry experts, that in the fast-food drive-thru industry customers trade off price and waiting time. More interestingly, our estimates indicate that consumers attribute a very high cost to the time they spend waiting.
Selection of Degrees of Freedom for Dynamic Analysis

A technique for the selection of dynamic degrees of freedom of large, complex structures for dynamic analysis is described and the formulation of Ritz basis vectors for component mode synthesis is presented. Generally, the selection of DDOF is left to the judgement of engineers. For large, complex structures, however, a danger of poor or improper selection of DDOF exists. An improper selection may result in singularity of the eigenvalue problem, or in missing some of the lower frequencies. This technique can be used to select the DDOF to reduce the size of large eigenproblems and to select the DDOF to eliminate the singularities of the assembled eigenvalue problem of components mode synthesis. The execution of this technique is discussed in this paper. Examples of using this technique in conjunction with a general purpose finite element computer program are given.
Fiduciary responsibility and bank-firm relationships: An analysis of shareholder voting by banks

Abstract An active market for corporate control has prompted corporate managers to lobby for measures that protect their positions. It has been argued that corporate managements have worked to entrench themselves at the expense of outside shareholders and have pressured institutional investors (including banks) to vote on corporate matters in a manner supportive of managements' proposals. One source of potential pressure arises when bank fiduciaries manage employee savings plans, pension funds, and engage in other fee generating corporate trust activities for firms whose shares they vote. In addition, banks often extend commercial credit to firms whose shares the trust division votes. Finally, director interlock between banks and corporations is likely to bias voting behavior. Fiduciary loyalty may be compromised by bankers' concern that failure to support management can threaten business relationships. The objective of this study is to investigate the effects of conflicting relationships on the voting behavior of banks as fiduciaries. The empirical results indicate that where director interlock and income-related relationships exist, banks tend to vote in favor of management antitakeover proposals; however, where these business relationships do not exist banks tend to vote against such proposals.
DISSIPATIONAL VERSUS DISSIPATIONLESS GALAXY FORMATION AND THE DARK MATTER CONTENT OF GALAXIES

We examine two extreme models for the build-up of the stellar component of luminous elliptical galaxies. In one case, we assume the build-up of stars is dissipational, with centrally accreted gas radiating away its orbital and thermal energy; the dark matter (DM) halo will undergo adiabatic contraction and the central DM density profile will steepen. For the second model, we assume the central galaxy is assembled by a series of dissipationless mergers of stellar clumps that have formed far from the nascent galaxy. In order to be accreted, these clumps lose their orbital energy to the DM halo via dynamical friction, thereby heating the central DM and smoothing the DM density cusp. The central DM density profiles differ drastically between these models. For the isolated elliptical galaxy, NGC 4494, the central DM densities follow the power laws r –0.2 and r –1.7 for the dissipational and dissipationless models, respectively. By matching the dissipational and dissipationless models to observations of the stellar component of elliptical galaxies, we examine the relative contributions of dissipational and dissipationless mergers to the formation of elliptical galaxies and look for observational tests that will distinguish between these models. Comparisons to strong lensing brightest cluster galaxies yield median (M */L) B ratios of 2.1 ± 0.8 and 5.2 ± 1.7 at z 0.39 for the dissipational and dissipationless models, respectively. For NGC 4494, the best-fit dissipational and dissipationless models have (M */L) B = 2.97 and 3.96. Comparisons to expected stellar mass-to-light ratios from passive evolution and population syntheses appear to rule out a purely dissipational formation mechanism for the central stellar regions of giant elliptical galaxies.
Integrated collaboration across distributed sites: the perils of process and the promise of practice

In an era where a strategic command of global resources is becoming a requisite for success, firms are struggling to successfully unify their onshore and offshore sites. The literature on global virtual teams generally frames the impediments to coordination and collaboration based on divergent nationally based cultural attributes, language barriers, and the limitations of information and communication technologies. Drawing on world-systems theory, this paper argues for a decrease in the importance afforded to national boundaries and individual sites, and a re-orientation to the social dynamics across sites regardless of nationality. By changing the unit of analysis to the organization as a world system and focusing on emergent practices, this paper provides new insights regarding globally distributed collaborative work and identifies how to manage global relations to overcome structural impediments, to develop positive social relations, and achieve collaboration.
Monte Carlo simulation of molecular flow in a neutral beam injector and comparison with experiment

Monte Carlo calculations have been performed to obtain estimates of the background gas pressure and molecular number density as a function of position in the PDX-prototype neutral beam injector, which has undergone testing at the Oak Ridge National Laboratory. Estimates of these quantities together with the transient and steady-state energy deposition and molecular capture rates on the cryopanels of the cryocondensation pumps and the molecular escape rate from the injector were obtained utilizing a detailed geometric model of the neutral beam injector. The molecular flow calculations were performed using an existing Monte Carlo radiation transport code, which was modified slightly to monitor the energy of the background gas molecules. The credibility of these calculations is demonstrated by the excellent agreement between the calculated and experimentally measured background gas pressure in front of the beamline calorimeter located in the downstream drift region of the injector. The usefulness of the calculational method as a design tool is illustrated by a comparison of the integrated beamline molecular density over the drift region of the injector for three modes of cryopump operation.
Layered XY Models, Anyon Superconductors, and Spin-Liquids

The partition function of the double-layer XY model in the (dual) Villain form is computed exactly in the limit of weak coupling between layers. Both layers are locked together through the Berezinskii-Kosterlitz-Thouless transition, while they decouple well inside the normal phase. These results are recovered in the general case of a finite number of layers. When re-interpreted in terms of the dual problems of lattice anyon superconductivity and of spin-liquids, they also indicate that the essential nature of the transition into the "normal" state found in two dimensions persists in the case of a finite number of weakly coupled layers.
Tits alternative for closed real analytic 4-manifolds of nonpositive curvature

Abstract We study subgroups of fundamental groups of real analytic closed 4-manifolds with nonpositive sectional curvature. In particular, we are interested in the following question: if a subgroup of the fundamental group is not virtually free Abelian, does it contain a free group of rank two? The technique involves the theory of general metric spaces of nonpositive curvature.
Torques on Spheroidal Silicate Grains Exposed to Anisotropic Interstellar Radiation Fields

Radiative torques, due to the absorption and scattering of starlight, are thought to play a major role in the alignment of grains with the interstellar magnetic field. The absorption of radiation also gives rise to recoil torques, associated with the photoelectric effect and photodesorption. The recoil torques are much more difficult to model and compute than the direct radiative torque. Here, we consider the relatively simple case of a spheroidal grain. Given our best estimates for the photoelectric yield and other relevant grain physical properties, we find that the recoil torques contribute at the ≈10% level or less compared with the direct radiative torque. We recommend that the recoil torques not be included in models of radiation-driven grain alignment at this time. However, additional experimental characterization of the surface properties and photoelectric yield for submicron grains is needed to better quantify the magnitude of these torques.
Supramolecular chemistry and chemical warfare agents: from fundamentals of recognition to catalysis and sensing

Supramolecular chemistry presents many possible avenues for the mitigation of the effects of chemical warfare agents (CWAs), including sensing, catalysis and sequestration. To-date, efforts in this field both to study fundamental interactions between CWAs and to design and exploit host systems remain sporadic. In this tutorial review the non-covalent recognition of CWAs is considered from first principles, including taking inspiration from enzymatic systems, and gaps in fundamental knowledge are indicated. Examples of synthetic systems developed for the recognition of CWAs are discussed with a focus on the supramolecular complexation behaviour and non-covalent approaches rather than on the proposed applications.
Fracture analysis of the NESC-1 spinning cylinder experiment

This paper presents finite-element analyses of the cylinder specimen being used in the international Network for Evaluating Steel Components (NESC) large-scale spinning-cylinder project (NESC-1). The objective of the NESC-1 project is to focus on a complete process for assessing the structural integrity of aged reactor pressure vessels. A new cylinder specimen was reconstituted from segments of the previously tested SC-4 and SC-6 specimens because the relatively high fracture toughness of the original specimen might preclude achieving the test objectives. The wall thickness is greater for the reconstituted specimen when compared with the previous specimen geometry (175 versus 150 mm). Also, the initial and coolant temperatures for the proposed thermal shock may be reduced as much as 25°C to increase the probability ofachieving cleavage initiation. Analyses were carried out to determine the combined effects of increasing the wall thickness and lowering the initial and coolant temperatures in the experiment. Estimates were made of the change in hoop strain on the clad inner surface directly above a subclad crack due to initiation and axial propagation of the crack. Three-dimensional finite-element models of the cladded cylinder were generated with 6:1 and 2:1 semi-elliptical 70-mm-deep subclad cracks. The cylinder specimen was subjected to thermal-shock and centrifugal loading conditions and analyzed with a thermo-elastic-plastic material model. The analytical results indicate that lowering the initial and coolant temperatures by 25°C will not significantly change the peak driving force, but will shift the stress-intensity factor (K I ) versus temperature curves so that the crack will become critical at an earlier time in the transient. The peak K I value occurs at a lower temperature (after the crack becomes critical), which increases the probability of achieving cleavage initiation. Also, the calculated hoop strains for the two crack aspect ratios (simulation of 2:1 crack propagating axially) provide an estimated change in hoop strain in the range of 3 to 4 percent on the clad inner surface.
A quantitative approach to multinational production

Abstract I examine new data on the number and revenues of foreign affiliates of multinational firms across a large number of country pairs. The data shed light on the behavior of the intensive and extensive margins of multinational production (MP). To capture the patterns observed in the data, I build and calibrate a multi-country general-equilibrium model of MP that combines a Lucas (1978) span-of-control with an Eaton and Kortum (2002) type model, and includes both fixed and variable costs of opening affiliates abroad. I use the calibrated model to calculate the gains that a country would experience from liberalizing access to foreign firms. Those calculations suggest that the welfare losses of closing up to foreign firms would be around 4%, while the gains of liberalizing access to foreign firms would be large, particularly if the variable – rather than the fixed – component of MP costs were lowered.
States and boundary terms: subtleties of lorentzian AdS/CFT

We complete the project of specifying the lorentzian AdS/CFT correspondence and its approximation by bulk semi-classical methods begun by earlier authors. At the end, the lorentzian treatment is self-contained and requires no analytic continuation from the euclidean. The new features involve a careful study of boundary terms associated with an initial time t− and a final time t+. These boundary terms are determined by a choice of quantum states. The main results in the semi-classical approximation are 1) The times t± may be finite, and need only label Cauchy surfaces respectively to the past and future of the points at which one wishes to obtain CFT correlators. Subject to this condition on t±, we provide a bulk computation of CFT correlators that is manifestly independent of t±. 2) As a result of (1), all CFT correlators can be expressed in terms of a path integral over regions of spacetime outside of any black hole horizons. 3) The details of the boundary terms at t± serve to guarrantee that, at leading order in this approximation, any CFT one-point function is given by a simple boundary value of the classical bulk solution at null infinity, I.
A measure of landscapes

This paper introduces a statistical fitness landscape analysis, based on Weinberger's random walk method and on a time series analysis known as the Box-Jenkins approach, to measure and express the correlation structure of fitness landscapes. The analysis has some additions to and advantages over previous methods for measuring this structure. The analysis is demonstrated on fitness landscapes constructed with Kauffman's NK-model, using two operators (point mutation and a form of crossover) and a combination of the two. Furthermore, the predictive value of the method is shown.
Do solar-neutrino experiments imply new physics?

None of the 1000 solar models in a full Monte Carlo simulation is consistent with the results of the chlorine or the Kamiokande experiments. Even if the solar models are forced artificially to have a [sup 8]B neutrino flux in agreement with the Kamiokande experiment, none of the fudged models agrees with the chlorine observations. The GALLEX and SAGE experiments, which currently have large statistical uncertainties, differ from the predictions of the standard solar model by 2[sigma] and 3[sigma], respectively.
Graphene-Wrapped Sulfur Particles as a Rechargeable Lithium–Sulfur Battery Cathode Material with High Capacity and Cycling Stability

We report the synthesis of a graphene–sulfur composite material by wrapping poly(ethylene glycol) (PEG) coated submicrometer sulfur particles with mildly oxidized graphene oxide sheets decorated by carbon black nanoparticles. The PEG and graphene coating layers are important to accommodating volume expansion of the coated sulfur particles during discharge, trapping soluble polysulfide intermediates, and rendering the sulfur particles electrically conducting. The resulting graphene–sulfur composite showed high and stable specific capacities up to ∼600 mAh/g over more than 100 cycles, representing a promising cathode material for rechargeable lithium batteries with high energy density.
Novel octahedral tungsten sulfidocyanide cluster anion [W6S8(CN)6]6−

Novel tungsten octahedral sulfidocyanide cluster compounds Na6[W6S8(CN)6]·18DMSO 1 and K6[W6S8(CN)6] 2 have been synthesized and characterized by X-ray crystallography and NMR spectroscopy.
A high-precision radial-velocity survey for other planetary systems

The precise measurement of variations in stellar radial velocities provides one of several promising methods of surveying a large sample of nearby solar type stars to detect planetary systems in orbit around them. The McDonald Observatory Planetary Search (MOPS) was started in 1987 September with the goal of detecting other nearby planetary systems. A stabilized I2 gas absorption cell placed in front of the entrance slit to the McDonald Observatory 2.7 m telescope coude spectrograph serves as the velocity metric. With this I2 cell we can achieve radial velocity measurement precision better than 10 ms-1 in an individual measurement. At this level we can detect a Jupiter-like planet around a solar-type star, and have some hope of detecting Saturn-like planets in a long-term survey. The detectability of planets is ultimately limited by stellar pulsation modes and photospheric motions. Monthly MOPS observing runs allow us to obtain at least 5 independent observations per year of the 33 solar-type (F5-K7) stars on our observing list. We present representative results from the first five years of the survey.
Skewed parton distributions

Abstract Applying perturbative QCD to hard exclusive electroproduction processes one is required to introduce generalized parton distributions. In this talk, I discuss double and skewed distributions, their basic structure, relation to hadronic form factors and usual (“forward”) parton densities, modeling SPDs and some recent applications.
Copper Catalyzed Atom Transfer Radical Addition (ATRA) and Cyclization (ATRC) Reactions in the Presence of Reducing Agents

This article reports on recent advances in the area of catalyst regeneration in copper mediated atom transfer radical addition (ATRA) and cyclization (ATRC) reactions using free‐radical diazo initiators as reducing agents. The role of reducing agent in both processes is to continuously regenerate the activator (copper(I) complex) from the deactivator (copper(II) complex). As a result, single addition adducts in ATRA and ATRC reactions can be synthesized using very low concentrations of copper catalysts (5–100 pm). Previously, efficient catalysis for both processes required as much as several thousands ppm of copper. It is envisioned that the recent developments in this area could have important industrial implications on the synthesis of small organic molecules, natural products and pharmaceutical drugs.
Community structure and trophic ecology of zooplankton in the scotia sea marginal ice zone in winter (1988)

Zooplankton community structure and trophic ecology were investigated in the marginal ice zone of the Southern Scotia Sea during the austral winter of 1988 as part of the AMERIEZ program. In the study area, near the South Orkneys (34–49°W, 57–61.5°S), water emerging from the Weddell Sea mixed with Scotia Sea water to form a complex field of mesoscale eddies and meanders. Three primary zooplankton communities were identified: a shallow cold water assemblage typical of Weddell Sea water; a shallow/upper mesopelagic assemblage of subantarctic species introduced into the southern Scotia Sea with warm core eddies from the Polar Front; and a deep (>400 m) mesopelagic community with circumtantartic species. Zooplankton numerical dominants were cyclopoid copepods (mostly Oithona spp.); biomass dominants were four calanoid copepods, Calanoides acutus, Rhincalanus gigas, Calanus propinquus and Metridia gerlachei. Calanoides acutus and R. gigas were undergoing winter diapause in the mesopelagic zone (>400 m) whereas M. gerlachei and C. propinquus were distributed throughout the water column. In the subantarctic eddies M. gerlachei was replaced by M. lucens as a dominant and R. gigas was more abundant than in cold water to the south. Diet analysis of 35 dominant species revealed five feeding guilds among the zooplankton. One consisted primarily of small herbivorous copepods. Two closely related guilds consisting of copepods, krill and salps were omnivorous, feeding on phytoplankton, protozoans, metazoans and crustacean debris (molts). Two guilds were constituted by predatory copepods and chaetognaths. A sixth group, all copepods, which included important numerical and biomass dominants of the region, was trophically inactive. A comparison of gut fullness between winter 1988 and fall 1986 revealed that all but two of 19 small particle grazing species had significantly less food in their guts in winter. The exceptions were the biomass dominants C. propinquus and M. gerlachei, which were actively feeding in winter. Phytoplankton biomass was low in winter, averaging two-thirds that in fall. Several major trophic pathways from phytoplankton through apex predators (birds and mammals) are proposed for winter in the southern Scotia Sea with zooplankton playing a central role in each.
The relative contributions of radiative forcing and internal climate variability to the late 20th Century winter drying of the Mediterranean region

The roles of anthropogenic climate change and internal climate variability in causing the Mediterranean region’s late 20th Century extended winter drying trend are examined using 19 coupled models from the Intergovernmental Panel on Climate Change Fourth Assessment Report. The observed drying was influenced by the robust positive trend in the North Atlantic Oscillation (NAO) from the 1960s to the 1990s. Model simulations and observations are used to assess the probable relative roles of radiative forcing, and internal variability in explaining the circulation trend that drove much of the precipitation change. Using the multi-model ensemble we assess how well the models can produce multidecadal trends of realistic magnitude, and apply signal-to-noise maximizing EOF analysis to obtain a best estimate of the models’ (mean) sea-level pressure (SLP) and precipitation responses to changes in radiative forcing. The observed SLP and Mediterranean precipitation fields are regressed onto the timeseries associated with the models’ externally forced pattern and the implied linear trends in both fields between 1960 and 1999 are calculated. It is concluded that the radiatively forced trends are a small fraction of the total observed trends. Instead it is argued that the robust trends in the observed NAO and Mediterranean rainfall during this period were largely due to multidecadal internal variability with a small contribution from the external forcing. Differences between the observed and NAO-associated precipitation trends are consistent with those expected as a response to radiative forcing. The radiatively forced trends in circulation and precipitation are expected to strengthen in the current century and this study highlights the importance of their contribution to future precipitation changes in the region.
On the worst case complexity of potential reduction algorithms for linear programming

There are several classes of interior point algorithms that solve linear programming problems in O(√nL) iterations. Among them, several potential reduction algorithms combine both theoretical (O(√nL) iterations) and practical efficiency as they allow the flexibility of line searches in the potential function, and thus can lead to practical implementations. It is a significant open question whether interior point algorithms can lead to better complexity bounds. In the present paper we give some negative answers to this question for the class of potential reduction algorithms. We show that, even if we allow line searches in the potential function, and even for problems that have network structure, the bound O(√nL) is tight for several potential reduction algorithms, i.e., there is a class of examples with network structure, in which the algorithms need at least Θ(√nL) iterations to find an optimal solution.
Regression Coefficient Identification Decay in The Presence of Infrequent Classification Errors

Abstract Recent evidence from Bound, Brown, and Mathiowetz (2001) and Black, Sanders, and Taylor (2003) suggests that reporting errors in survey data routinely violate all of the classical measurement error assumptions. The econometrics literature has not considered the consequences of fully arbitrary measurement error for identification of regression coefficients. This paper highlights the severity of the identification problem given the presence of even infrequent arbitrary errors in a binary regressor. In the empirical component, health insurance misclassification rates of less than 1.3% generate double-digit percentage point ranges of uncertainty about the variable's true marginal effect on the use of health services.
A general and mild two-step procedure for the synthesis of aryl and heteroaryl sulfonamides from the corresponding iodides

Abstract A mild two-step preparation of aryl and heteroaryl sulfonyl chlorides and sulfonamides from their corresponding iodides is developed. Acid labile functionalities are shown to be stable under both the copper-catalysed coupling and the subsequent oxidative chlorination.
Auger characterization of new and aged dispenser cathode surfaces

Abstract The major changes in dispenser cathode surface signatures caused by aging were studied on B-type dispenser cathodes by operating them at high temperatures. By means of a computerized scanning Auger microprobe (SAM), the surface characterizations of three aged cathodes were measured and compared with those of a new cathode. Several hundred points were monitored on each sample to develop a good statistical description of each cathode surface, including both the impregnated pore ends and the tungsten regions between the pores. A method of discrimination between impregnant regions and tungsten regions has been developed, based on differences in the oxygen Auger peak shape and position. The results show that a surprisingly large fraction (> 70%) of the new cathode surface could be similar to the impregnant. This fraction decreases to near 20% with age. The elemental composition of these different regions was examined by correlating the presence of each element to others. The elemental correlation showed that the dominant fraction of the cathode surface in early life is similar to a barium oxide on tungsten, and the cathode changes to an increasing fraction of surface tungsten oxide with aging.
A scalable approach to combinatorial library design for drug discovery

In this paper, we propose an algorithm for the design of lead generation libraries required in combinatorial drug discovery. This algorithm addresses simultaneously the two key criteria of diversity and representativeness of compounds in the resulting library and is computationally efficient when applied to a large class of lead generation design problems. At the same time, additional constraints on experimental resources are also incorporated in the framework presented in this paper. A computationally efficient scalable algorithm is developed, where the ability of the deterministic annealing algorithm to identify clusters is exploited to truncate computations over the entire data set to computations over individual clusters. An analysis of this algorithm quantifies the tradeoff between the error due to truncation and computational effort. Results applied on test data sets corroborate the analysis and show improvement by factors as large as 10 or more, depending on the data sets.
A family of linear integrated circuits for data systems

The rapid expansion of automated digital data processing has created a need for low-cost analog data acquisition, display and control equipment. This implies low-cost D/A and A/D conversion equipment. This paper describes the resulting family of linear integrated circuits satisfying this need.
Three long-lived excited states of Tm -

Considering p, d, and f attachments to the 4f{sup 13}6s{sup 2} J=(7/2) ground state of Tm I, we find no evidence for bound Tm{sup -} states. A survey of possible weak attachments to excited Tm I states, however, suggests three long lived states created by 6p attachment to the 4f{sup 12}5d6s{sup 2} J=(15/2),(17/2) excited states. Calculated binding energies for these states are 254 meV for the J=8 state relative to its 4f{sup 12}5d6s{sup 2} J=(15/2) threshold and 258 and 173 meV relative to the J=(17/2) threshold for J=9 and J=10, respectively. These high J 4f{sup 12}5d6s{sup 2}6p states have open decay channels only to 4f{sup 13}6s{sup 2} J=(7/2),(5/2) and 4f{sup 12}5d6s{sup 2} J=(9/2), resulting in emitted electrons of symmetry {epsilon}g, {epsilon}h, and {epsilon}i. The lifetimes for these long lived J=8,9,10 states are estimated to be 9.8 {mu}s, 0.9 ms, and 6.6 ms, respectively.
Application of “one-bead one-compound” combinatorial library methods in signal transduction research

Abstract Using a “split-synthesis” solid phase synthetic approach, bead libraries can be generated such that each bead displays only one chemical entity. This “one-bead one-compound” combinatorial library can then be assayed for specific biological properties using either a solid-phase on-bead binding or functional assay, or a releasable solution phase assay. Positive compound-beads can then be isolated for structure determination. Various assay systems to screen such a “one-bead one-compound” library are described. We have used this combinatorial library method to discover peptides that bind to the cell surface immunoglobulins of murine lymphoma cells. Such peptides, when presented in an oligomeric form to a lymphoma cell are able to induce signal transduction. Additionally, we have also applied the “one-bead onecompound” combinatory library approach to elucidate peptide substrate motifs for protein tyrosine kinases. Multiple distinct peptide motifs were identified for p60 c-src protein tyrosine kinase. Using the identified peptide substrates as templates, potent and highly specific pseudosubstrate-based peptide inhibitors were developed.
The relative permeability of iron, nickel and permalloy in high frequency electromagnetic fields

Abstract The relative magnetic permeability of iron, nickel and permalloy was measured over the range of wave-lengths from 70 to 200 meters by the heterodyne balance method and by the resonance method. Nothing suggestive of the anomalous dispersion of the magnetic permeability reported in this region by Wwedensky and Theodortschik was found when certain precautions were observed in carrying out the measurements. When these precautions were neglected irregular breaks resulted in the curves of permeability as a function of wavelength which varied in position with the conditions of the circuit. The high frequency resistance of iron, nickel and permalloy wires was measured over the range of approximately fifty thousand kilocycles from two to three meter wave-lengths. What appeared to be anomalous variations at certain frequencies were found not to exist when the proper precautions were observed in making the measurements.
Numerical simulation of fracture mode transition in ductile plates

Fracture mode of ductile solids can vary depending on the history of stress state the material experienced. For example, ductile plates under remote in-plane loading are often found to rupture in mode I or mixed mode I/III. The distinct crack patterns are observed in many different metals and alloys, but until now the underlying physical principles, though highly debated, remain unresolved. Here we show that the existing theories are not capable of capturing the mixed mode I/III due to a missing ingredient in the constitutive equations. We introduce an azimuthal dependent fracture envelope and illustrate that two competing fracture mechanisms, governed by the pressure and the Lode angle of the stress tensor, respectively, exist ahead of the crack tip. Using the continuum damage plasticity model, we demonstrate that the distinctive features of the two crack propagation modes in ductile plates can be reproduced using three dimensional finite element simulations. The magnitude of the tunneling effect and the apparent crack growth resistance are calculated and agree with experimental observations. The finite element mesh size dependences of the fracture mode and the apparent crack growth resistance are also investigated.
Wing-flutter calculations with the CAP-TSD unsteady transonic small-disturbance program

The application and assessment is described of CAP-TSD (Computational Aeroelasticity Program - Transonic Small Disturbance) code for flutter prediction. The CAP-TSD program was developed for aeroelastic analysis of complete aircraft configurations and was previously applied to the calculation of steady and unsteady pressures. Flutter calculations are presented for two thin, swept-and-tapered wing planforms with well defined modal properties. The calculations are for Mach numbers from low subsonic to low supersonic values, including the transonic range, and are compared with subsonic linear theory and experimental flutter data. The CAP-TSD flutter results are generally in good agreement with the experimental values and are in good agreement with subsonic linear theory when wing thickness is neglected.
Change of Solar Oscillation Eigenfrequencies with the Solar Cycle

Solar p-mode eigenfrequencies depend on the radial stratification of the solar interior and this stratification may be perturbed by the mechanism of the 11-year magnetic activity cycle. Observations of long-term changes in p-mode oscillation frequencies may therefore help to identify the cause of the solar cycle. A comparative analysis of two separate years of data (1980, 1984) from the ACRIM instrument on the Solar Maximum Mission satellite was performed to access the level of frequency variation over the declining phase ( ~ 1980–1984) of the activity cycle. The difference for the two epochs (1980 minus 1984) in the mean frequency- of nine l =0 and l =1 oscillation peaks in the ACRIM power spectrum is $$ \Delta v = 0.42 \pm 0.14\mu Hz $$ the mean frequency of these modes was approximately 1.3 parts in 104 higher at the epoch of sunspot maximum ( ~ 1980) than at the later epoch. Analysis of synthetic oscillation data seems to rule out possible frequency pulling effects due to differences between the 1980 and 1984 observing windows as the cause of the observed variation.
Powers of the Euler product and commutative subalgebras of a complex simple Lie algebra

If \(\mathfrak{g}\) is a complex simple Lie algebra, and k does not exceed the dual Coxeter number of \(\mathfrak{g}\), then the absolute value of the kth coefficient of the \(\dim\mathfrak{g}\) power of the Euler product may be given by the dimension of a subspace of \(\wedge^k\mathfrak{g}\) defined by all abelian subalgebras of \(\mathfrak{g}\) of dimension k. This has implications for all the coefficients of all the powers of the Euler product. Involved in the main results are Dale Peterson’s 2rank theorem on the number of abelian ideals in a Borel subalgebra of \(\mathfrak{g}\), an element of type ρ and my heat kernel formulation of Macdonald’s η-function theorem, a set Dalcove of special highest weights parameterized by all the alcoves in a Weyl chamber (generalizing Young diagrams of null m-core when \(\mathfrak{g}= \text{Lie}\,\mathit{Sl}(m,\mathbb{C})\)), and the homology and cohomology of the nil radical of the standard maximal parabolic subalgebra of the affine Kac–Moody Lie algebra.
Reconstruction of a low-rank matrix in the presence of Gaussian noise

Abstract This paper addresses the problem of reconstructing a low-rank signal matrix observed with additive Gaussian noise. We first establish that, under mild assumptions, one can restrict attention to orthogonally equivariant reconstruction methods, which act only on the singular values of the observed matrix and do not affect its singular vectors. Using recent results in random matrix theory, we then propose a new reconstruction method that aims to reverse the effect of the noise on the singular value decomposition of the signal matrix. In conjunction with the proposed reconstruction method we also introduce a Kolmogorov–Smirnov based estimator of the noise variance. We show with an extensive simulation study that the proposed method outperforms oracle versions of both soft and hard thresholding methods, and closely matches the performance of the oracle orthogonally equivariant method.
The heterocyclic ring of 4-substituted-1,8-naphthalimides is NOT inert to nucleophilic attack, contrary to earlier reports

The heterocyclic ring of N-aryl-4-chloro-1,8-naphthalimides, reported to be resistant to nucleophilic attack, reacts with primary amine nucleophiles at room temperature to give 4-chloro-N-alkyl-1,8-naphthalimides. The reaction is first order in the naphthalimide. The Hammett plot is linear (R2 0.996) with a large positive slope (+3.0), consistent with substantial negative charge development at nitrogen in the activated complex.
Eddy diffusivity near bubble plumes

[1] Profiles of eddy diffusivity and the rate of dissipation of temperature variance were inferred from temperature microstructure measurements near a bubble plume at the center of a tank with a diameter of 13.7 m and a maximum depth of 8.3 m. Measurements occurred outside the bubbly part of the flow. Profiles of eddy diffusivity were estimated with two methods: one based on the equation for turbulent kinetic energy and one based on the equation for temperature variance. The eddy diffusivities showed nonmonotonic behavior with distance from the plume axis, as in numerical simulations. Eddy diffusivities estimated with the two methods match well, except for one data set with strong turbulence and weak stratification. The estimates of the eddy diffusivity allow two empirical formulas for the bulk, or tank-averaged, effective diffusivity to be evaluated; the bulk diffusivity is within the range of values predicted by the models.