cssi/SciSciGPT-SciSciNet huggingface dataset:
A Critical Examination of Hypernova Remnant Candidates in M101. II. NGC 5471B

NGC 5471B has been suggested to contain a hypernova because of its extraordinarily bright X-ray emission. To assess its true nature, we have obtained high-resolution images in continuum bands and nebular lines with the Hubble Space Telescope, and high-dispersion long-slit spectra with the Kitt Peak National Observatory 4 m echelle spectrograph. The images reveal three supernova remnant (SNR) candidates in the giant H II region NGC 5471, the brightest one being the 77 × 60 pc shell in NGC 5471B. The Hα velocity profile of NGC 5471B can be decomposed into a narrow component (FWHM 41 km s-1) from the background H II region and a broad component (FWHM 148 km s-1) from the SNR shell. Using the brightness ratio of the broad to narrow components and the Hα flux measured from the WFPC2 Hα image, we derive a Hα luminosity of (1.4 ± 0.1) × 1039 ergs s-1 for the SNR shell. The [S II] λ6716/λ6731 doublet ratio of the broad velocity component is used to derive an electron density of ~700 cm-3 in the SNR shell. The mass of the SNR shell is thus 4600 ± 500 M⊙. With a ~330 km s-1 expansion velocity implied by the extreme velocity extent of the broad component, the kinetic energy of the SNR shell is determined to be 5 × 1051 ergs. This requires an explosion energy greater than 1052 ergs, which can be provided by one hypernova or multiple supernovae. Comparing to SNRs in nearby active star formation regions, the SNR shell in NGC 5471B appears truly unique and energetic. We conclude that the optical observations support the existence of a hypernova remnant in NGC 5471B.
On the regularity of the flow map for the gravity-capillary equations

Abstract We prove via explicitly constructed initial data that solutions to the gravity-capillary wave system in R 3 representing a 2 d air–water interface immediately fail to be C 3 with respect to the initial data if the initial data ( h 0 , ψ 0 ) ∈ H s + 1 2 ⊗ H s for s 3 . Similar results hold in R 2 domains with a 1 d interface. Furthermore, we discuss the related threshold for the pure gravity water wave system.
Real-Time Viewing Of Dynamic Processes On Cdte Surfaces At Elevated Temperature

Online video recording with a high-resolution electron microscope has been used to study real-time atomic events occurring at cadmium telturide surfaces over a range of temperatures from 27°C to 500°C. Using the profile imaging mode of observation, different types of surface activity have been documented on (001), (111) and (110) surfaces. For example, the (001) surfaces displayed reversible phase transformations between 2×1 and 3×1 reconstructions at a transition temperature of about 200°C. The (111) surfaces exhibited sublimation by a ledge mechanism that depended upon the terminating surface: layer-by-layer removal invariably occurred for (110) surface terminations whereas bilayer removal was usually seen for terminations by (100) surfaces. Finally, the (110) surface rearranged by a hopping mechanism, but no substantial loss of material was observed.
Method of Analytic Evolution of Flat Distribution Amplitudes in QCD

A new analytical method of performing ERBL evolution is described. The main goal is to develop an approach that works for distribution amplitudes that do not vanish at the end points, for which the standard method of expansion in Gegenbauer polynomials is inefficient. Two cases of the initial DA are considered: a purely flat DA, given by the same constant for all x, and an antisymmetric DA given by opposite constants for x ≷ 1/2. For a purely flat DA, the evolution is governed by an overall dependence on the evolution parameter t times a factor that was calculated as an expansion in t. For an antisymmetric flat DA, an extra overall factor |1 - 2x|2t appears due to a jump at x = 1/2. A good convergence was observed in the t ≲ 1/2 region. For larger t, one can use the standard method of the Gegenbauer expansion.
Physical Entities and Mathematical Representation

Certain basic postulates about physical observables yield the structure of their mathematical representation. Measure equations are contrasted with quantity equations, and measurement units with abstract units. The abstract vector spaces in which observables are represented comprise the core of dimensional analysis. Systems of equations, units, and dimensions are discussed, along with comments on rationalization. The problem of assigning a dimension to angle is discussed, and a new proposal offered.
A spatial simulation approach to account for protein structure when identifying non-random somatic mutations.

Current research suggests that a small set of “driver” mutations are responsible for tumorigenesis while a larger body of “passenger” mutations occur in the tumor but do not progress the disease. Due to recent pharmacological successes in treating cancers caused by driver mutations, a variety of methodologies that attempt to identify such mutations have been developed. Based on the hypothesis that driver mutations tend to cluster in key regions of the protein, the development of cluster identification algorithms has become critical. We have developed a novel methodology, SpacePAC (Spatial Protein Amino acid Clustering), that identifies mutational clustering by considering the protein tertiary structure directly in 3D space. By combining the mutational data in the Catalogue of Somatic Mutations in Cancer (COSMIC) and the spatial information in the Protein Data Bank (PDB), SpacePAC is able to identify novel mutation clusters in many proteins such as FGFR3 and CHRM2. In addition, SpacePAC is better able to localize the most significant mutational hotspots as demonstrated in the cases of BRAF and ALK. The R package is available on Bioconductor at: http://www.bioconductor.org/packages/release/bioc/html/SpacePAC.html . SpacePAC adds a valuable tool to the identification of mutational clusters while considering protein tertiary structure.
Group-theoretic evidence for SO(10) grand unification

Abstract The hypercharges of the fermions are not uniquely determined in SO(10) grand unification, but rather depend upon which linear combination of the two U(1) subgroups of SO(10)⊃SU(3)×SU(2)×U(1)×U(1) remains unbroken. We show that, in general, a given hypercharge assignment can be obtained only with very high-dimensional Higgs representations. The observation that the standard model is obtained with low-dimensional Higgs representations can therefore be regarded as further evidence for SO(10) grand unification. This evidence is independent of the fact that SO(10) ⊃ SU(5).
Ergodicity of the tip of an SLE curve

We first prove that, for \(\kappa \in (0,4)\), a whole-plane \(\hbox {SLE}(\kappa ;\kappa +2)\) trace stopped at a fixed capacity time satisfies reversibility. We then use this reversibility result to prove that, for \(\kappa \in (0,4)\), a chordal \(\hbox {SLE}_\kappa \) curve stopped at a fixed capacity time can be mapped conformally to the initial segment of a whole-plane \(\hbox {SLE}(\kappa ;\kappa +2)\) trace. A similar but weaker result holds for radial \(\hbox {SLE}_\kappa \). These results are then used to study the ergodic behavior of an SLE curve near its tip point at a fixed capacity time. The proofs rely on the symmetry of backward SLE weldings and conformal removability of \(\hbox {SLE}_\kappa \) curves for \(\kappa \in (0,4)\).
Additive-pulse mode-locking/limiting storage ring

A pulse-storage ring is an optical device capable of memorizing a pulse sequence of 0's and l's. The soliton ring of Nakazawa et al. [Electron. Lett. 29, 729 (1993)] with nearly unlimited transmission distance is such a device. We propose and experimentally demonstrate a different type of pulse-storage ring that uses intensity-dependent interferometric action to create a stronger intracavity transmission differential between the 0's and the l's.
Investigating the possible anomaly between nebular and stellar oxygen abundances in the dwarf irregular galaxy WLM

We obtained new optical spectra of 13 H II regions in WLM with EFOSC2; oxygen abundances are derived for nine H II regions. The temperature-sensitive [O III] λ4363 emission line was measured in two bright H II regions, HM 7 and HM 9. The direct oxygen abundances for HM 7 and HM 9 are 12 + log(O/H) = 7.72 ± 0.04 and 7.91 ± 0.04, respectively. We adopt a mean oxygen abundance of 12 + log(O/H) = 7.83 ± 0.06. This corresponds to [O/H] = -0.83 dex, or 15% of the solar value. In H II regions where [O III] λ4363 was not measured, oxygen abundances derived with bright-line methods are in general agreement with direct values of the oxygen abundance to an accuracy of about 0.2 dex. In general, the present measurements show that the H II region oxygen abundances agree with previous values in the literature. The nebular oxygen abundances are marginally consistent with the mean stellar magnesium abundance ([Mg/H] = -0.62). However, there is still a 0.62 dex discrepancy in oxygen abundance between the nebular result and the A-type supergiant star WLM 15 ([O/H] = -0.21). Nonzero reddening values derived from Balmer line ratios were found in H II regions near a second H I peak. There may be a connection between the location of the second H I peak, regions of higher extinction, and the position of WLM 15 on the eastern side of the galaxy.
The trace norm of r-partite graphs and matrices

Abstract The trace norm of graphs has been widely studied under the name graph energy. This note presents bounds on the maximum trace norm of an r-partite graph of order n. The lower bounds come from conference and Hadamard matrices.
Multicatalysis: Advancing Synthetic Efficiency and Inspiring Discovery

Heavy reliance on iterative synthetic strategies represents one of the most serious drawbacks of modern organic synthesis. There has been increasing interest of late in the development of processes that attempt to alleviate this dependence by achieving multiple transformations in a single vessel, thereby circumventing the need for intermittent isolation and purification. One such strategy is encompassed by the term multicatalysis, an approach wherein multiple catalytic reactions are executed in a single flask, either in tandem or sequentially. In this Minireview, some recent efforts in the field of multicatalysis, including our own work, are discussed. In addition, a case regarding the need for consistent terminology in this rapidly developing field is advanced.
An Extension of Hörmander’s Hypoellipticity Theorem

Motivated by applications to stochastic differential equations, an extension of Hormander’s hypoellipticity theorem is proved for second-order degenerate elliptic operators with non-smooth coefficients. The main results are established using point-wise Bessel kernel estimates and a weighted Sobolev inequality of Stein and Weiss. Of particular interest is that our results apply to operators with quite general first-order terms.
Ararat and Collective Memories of the Armenian Genocide

Atom Egoyan’s Ararat (2002) has been misread and inappropriately critiqued as a failed cinematic representation of the Armenian genocide. The author of this article argues that the film is instead an ambitious meditation on the question of how to represent genocide in general, and the Armenian genocide specifically. He traces a number of themes in Ararat, including the political stakes involved in genocide commemoration, the reasons for and costs of denial, the difficulty and urgency of constructing a past when only ruins remain, the problematic nature of cinematic treatments of genocide, the intensely personal ways in which collective memory helps to shape individual and family identities, and the complexities of determining which versions of the past are reliable. Further, the author discusses the possible consequences of the film’s clearly unintended suggestion that, ultimately, there are no solid criteria for choosing between competing versions of the past.
NRQCD Factorization and Quarkonium Production at Hadron-Hadron and ep Colliders

I review the NRQCD factorization approach for quarkonium production and compare its predictions with measurements in hadron-hadron and ep collisions.
Advanced Pogo stability analysis for liquid rockets

An advanced modeling method for determining engine-coupled Pogo oscillation modes, with general applicability to any liquid rocket vehicle, is presented. The modes result from interaction of structural vibrations with pressure and flow oscillations in the liquid propulsion system. A time-invariant linearized mathematical model of the system is developed for a selected flight time. Perturbations of the propulsion system are modeled using finite element representations for its physical elements (such as flow duct, pump, accumulator, and thrust chamber), each of which undergoes structural motion described in terms of the vibration modes of the overall vehicle. The structural modes, developed in a separate analysis, are determined with the fluids frozen in place in the feedlines and engines and involve motions of the propulsion elements. The system equations are written in a homogeneous second-order matrix form in the Laplace domain, yielding coefficient matrices that are all complex, unsymmetric, and singular. The major advances are 1) rigorous treatment of arbitrary translational motions of the vessels through which the fluids flow, including all forces (pressure area, inertial, and momentum) that react on the structural system, and 2) a powerful numerical eigensolver that yields eigenvalues and eigenvectors directly, without requiring elimination of dependent fluid state variables (pressure and flows).
Wave Invariants for Non-degenerate Closed Geodesics

This paper generalizes the methods and results of our article xxx.lanl.gov math.SP/0002036 from elliptic to general non-degenerate closed geodesics. The main purpose is to introduce a quantum Birkhoff normal form of the Laplacian at a general non-degenerate closed geodesic in the sense of V.Guillemin. Guillemin proved that the coefficients of the normal form at an elliptic closed geodesic could be determined from the wave invariants of this geodesic. We give a new proof, and extend its range to any non-degenerate closed geodesic.
Mass degeneracies in self-dual models☆

Abstract An algebraic restriction of the nonabelian self-dual Chem-Simons-Higgs systems leads to coupled abelian models with interesting mass spectra. The vacua are characterized by embeddings of SU (2) into the gauge algebra, and in the broken phases the gauge and real scalar masses coincide, reflecting the relation of these self-dual models to N = 2 SUSY. The masses themselves are related to the exponents of the gauge algebra, and the self-duality equation is a deformation of the classical Toda equations.
Price elasticities from survey data: Extensions and Indonesian results

This paper extends and improves the author's earlier work on measuring own and cross price elasticities from spatial variation in prices using household survey data. Double-logarithmic demand functions are replaced by functions that relate budget shares to the logarithms of prices and incomes, and zero expenditures are treated appropriately. Formulae are developed for estimation and for the calculation of standard errors. Limited Monte Carlo evidence suggests that the asymptotic regressions work well in practice. A large commodity system of food demands is estimated using Indonesian data from 1981.
Characterizing secondary debris impact ejecta

All spacecraft in low earth orbit are subject to high-speed impacts by meteoroids and orbital debris particles. These impacts can damage flight-critical systems, which can in turn lead to catastrophic failure of the spacecraft. In addition to threatening the operation of the spacecraft itself, on-orbit impacts also generate a significant amount of damaging ricochet ejecta particles. These high-speed particles can destroy critical external spacecraft subsystems, which also poses a threat to the spacecraft and its inhabitants. Since the majority of on-orbit debris impacts are expected to occur at oblique angles, the characterization of ricochet debris created in an orbital debris particle impact is an issue that must be addressed. This paper presents the results of a study performed to develop an empirical model that characterizes the secondary ejecta created by a high speed impact on a typical aerospace structural surface. Specifically, the model predicts the spread and trajectory of ricochet debris particles created in a hypervelocity impact as well as the size an velocity of the most damage particle in the ricochet debris cloud. Results obtained using the model are compared with experimental results and predictions obtained in a previous study.
Four Southern A-type Supergiants.

Measures of line intensities from high-dispersion spectrograms of HD 92207, 100262, 125835 and 161912 are presented. Analysis with a theoretical curve of growth leads to the selection of parameters for excitation temperature and microturbulence. The turbulent velocity in the atmosphere of HD 92207 varies through a factor of two in approximately one month, in phase with a similar change in the equivalent width of Hγ. The spectra of the other three stars do not appear to vary, but the turbulent velocity is much less for Fei than for Feii and Crii.
Derivation of the Euler equations from quantum dynamics

We derive the Euler equations from quantum dynamics for a class of fermionic many-body systems. We make two types of assumptions. The first type are physical assumptions on the solution of the Euler equations for the given initial data. The second type are a number of reasonable conjectures on the statistical mechanics and dynamics of the Fermion Hamiltonian.
Major depressive disorder: new clinical, neurobiological, and treatment perspectives

In this Seminar we discuss developments from the past 5 years in the diagnosis, neurobiology, and treatment of major depressive disorder. For diagnosis, psychiatric and medical comorbidity have been emphasised as important factors in improving the appropriate assessment and management of depression. Advances in neurobiology have also increased, and we aim to indicate genetic, molecular, and neuroimaging studies that are relevant for assessment and treatment selection of this disorder. Further studies of depression-specific psychotherapies, the continued application of antidepressants, the development of new treatment compounds, and the status of new somatic treatments are also discussed. We address two treatment-related issues: suicide risk with selective serotonin reuptake inhibitors, and the safety of antidepressants in pregnancy. Although clear advances have been made, no fully satisfactory treatments for major depression are available.
Modeling of pullulan fermentation by using a color variant strain of Aureobasidium pullulans

Abstract Pullulan, which is comprised of glucose units, is a simple linear polysaccharide produced by Aureobasidium pullulans. Pullulan has long been used in various applications such as blood plasma substitutes, food additives, adhesive additives, flocculants, and even environmental pollution control agents. Mathematical models of biomass, pullulan, and sucrose profiles during fermentation not only provide information about the kinetic-metabolic nature of pullulan, but also facilitate the control and optimization of pullulan production. In this study, several models were modified and tested in order to describe biomass, pullulan, and sucrose profiles during batch fermentation using a color variant strain of A. pullulans. The results demonstrated that the modified Gompertz model can serve as a universal equation to fit biomass production, pullulan production, and sucrose consumption. Furthermore, validation of this modified Gompertz model indicated that biomass (slope = 1.00, R2 = 0.991), pullulan (slope = 1.10, R2 = 0.991), and sucrose (slope = 0.96, R2 = 0.991) were all predicted accurately.
Economic Theory and the Financial Crisis

I want to probe in the role of the market in allocating resources in this very preliminary essay. One does not have to see study deeply to that the failure of markets for various kinds of derivative securities to perform properly is an essential element of the current financial crisis. Actually, financial crises are not a new phenomenon. The history of capitalism has been marked by repeated collapses of the financial system, situations in which the "markets" for loans disappear for extensive periods of time. The 18th century saw some bubbles, but these might not be quite modern. But from 1819 on, there have a succession of failures of banks and other financial institutions. These have typically been unpredicted and did not correspond in time to any particular exogenous event (e.g., wars). Economists from Joho Stuart Mill (1848) on did recognize the phenomenon. But the discussion was and is not at all integrated with the general exposition of classical economics. No one could be a more vigorous advocate of unrestrained markets than Milton Friedman; yet, to my reading, the account that he and Anna Schwartz gave of monetary developments in the United States and particularly with regard to the Great Depression emphasizes, not prices, not even interest rates, but the supply of money, and, by inference, of liquidity. (Friedman and Schwartz (1963)). I start with the neoclassical general equilibrium framework, to which I have given a good deal of attention and effort. I seek to identify a possible point at which it fails to supply a coherent theory of securities markets and so might possibly lead to some understanding of the repeated crises of the financial system underlying the development of capitalism.
Fourier-space crystallography as group cohomology

We reformulate Fourier-space crystallography in the language of cohomology of groups. Once the problem is understood as a classification of linear functions on the lattice, restricted by a particular group relation and identified by gauge transformation, the cohomological description becomes natural. We review Fourier-space crystallography and group cohomology, quote the fact that cohomology is dual to homology, and exhibit several results, previously established for special cases or by intricate calculation, that fall immediately out of the formalism. In particular, we prove that two phase functions are gauge equivalent if and only if they agree on all their gauge-invariant integral linear combinations and show how to find all these linear combinations systematically.
Time-Varying Correlation in Housing Prices

In the wake of the housing crisis, credit rating agencies have received much blame, particularly for the statistical tools they used to measure correlations in housing prices in different locations. Several studies have proposed alternative statistical models, but to date, all such approaches assume that correlations remain constant over time. This paper argues that, regardless of the correlation patterns built into such statistical models, correlations might strengthen during times of financial turmoil. Consequently, mortgage-backed securities might have been appropriately diversified during “ normal” times, but less so during extreme market swings. Using monthly data on housing prices in four major U.S. cities, the main findings confirm that housing prices do, indeed, exhibit correlations that change over time, and more importantly, those correlations appear to strengthen in the midst of market turmoil.
Probing the electronic structure of early transition metal oxide clusters: Molecular models towards mechanistic insights into oxide surfaces and catalysis

Abstract Selected recent works from the authors’ laboratory on the intrinsic electronic and structural properties of early transition metal oxide clusters are reviewed. These clusters provide well-defined molecular models pertinent to mechanistic understandings of complex oxide surface chemistry and catalysis. The energy gap evolution with cluster size was probed for the stoichiometric (TiO 2 ) n − , (V 2 O 5 ) n − , and (CrO 3 ) n − clusters, and each system was shown to approach the band gap of bulk oxides in a unique way. A variety of other model clusters have been characterized, such as the oxygen radical or diradical on a single W 6+ site in WO 4 − /WO 4 , the superoxide (WO 3 ) n (O 2 − ) complexes for dioxygen activation, and terminal versus bridging oxygen in M 3 O 2 − (M = Nb, Ta) clusters. Novel chemical bonding has been observed in a number of oxide clusters. The W 3 O 9 − and W 3 O 9 2− clusters were found to possess d-orbital aromaticity, whereas δ-aromaticity was discovered in the Ta 3 O 3 − cluster.
Long-term trends in intraocular pressure after pars plana vitrectomy.

Purpose To evaluate the effect of vitrectomy on intraocular pressure (IOP). Methods Retrospective cohort study. Medical records of 101 eyes of 101 patients undergoing nonemergent vitrectomy were reviewed for rates of open-angle glaucoma, increased IOP of >4 mmHg from baseline, change in IOP from baseline, and cataract formation. Preoperative and last measured IOPs were recorded. Baseline risk characteristics including lens status and diabetes were analyzed. Main outcome measures were 1) incidence of open-angle glaucoma; 2) increase in IOP of >4 mmHg; and 3) change in IOP. Results Mean follow-up was 49 months (range, 12-105 months). Mean baseline IOP was 15.3 mmHg, and mean final IOP was 15.8 mmHg (P = 0.3). At the most recent examination, 35 study eyes had a decrease in IOP from baseline, while 14 eyes had no change and 52 eyes had an increase in IOP. Four study eyes were newly diagnosed with ocular hypertension. No study eye developed open-angle glaucoma or required medical, laser, or surgical treatment for glaucoma. Incidence of increased IOP of >4 was 7% at 4 years and 34% at 8 years. Subgroup analysis of 66 patients comparing study eyes with nonvitrectomized fellow eyes demonstrated no significant difference in rates of increased IOP of >4 (P = 0.85). Neither diabetes nor pseudophakia was associated with significantly increased IOP. Conclusion In this series, vitrectomy does not appear to increase IOP even after removal of the crystalline lens.
Matter Bounce Cosmology with the f(T) Gravity

We show that the f(T) gravitational paradigm, in which gravity is described by an arbitrary function of the torsion scalar, can provide a mechanism for realizing bouncing cosmologies, thereby avoiding the Big Bang singularity. After constructing the simplest version of an f(T) matter bounce, we investigate the scalar and tensor modes of cosmological perturbations. Our results show that metric perturbations in the scalar sector lead to a background-dependent sound speed, which is a distinguishable feature from Einstein gravity. Additionally, we obtain a scale-invariant primordial power spectrum, which is consistent with cosmological observations, but suffers from the problem of a large tensor-to-scalar ratio. However, this can be avoided by introducing extra fields, such as a matter bounce curvaton.Communicated by P R L V Moniz
Structural synthesis of integrally stiffened cylinders.

Structural design of stiffened cylindrical shells, discussing minimum weight, prevention of buckling modes, etc
Gender and the influence of peer alcohol consumption on adolescent sexual activity.

I consider the alcohol consumption of opposite-gender peers as explanatory to adolescent sexual intercourse and demonstrate that female sexual activity is higher where there is higher alcohol consumption among male peers. This relationship is robust to school fixed effects, cannot be explained by broader cohort effects or general antisocial behaviors in male peer groups, and is distinctly different from any influence of the alcohol consumption of female peers which is shown to have no influence on female sexual activity. There is no evidence that male sexual activity responds to female peer alcohol consumption. (JEL J13, I12)
Roomy: a system for space limited computations

There are numerous examples of problems in symbolic algebra in which the required storage grows far beyond the limitations even of the distributed RAM of a cluster. Often this limitation determines how large a problem one can solve in practice. Roomy provides a minimally invasive system to modify the code for such a computation, in order to use the local disks of a cluster or a SAN as a transparent extension of RAM.Roomy is implemented as a C/C++ library. It provides some simple data structures (arrays, unordered lists, and hash tables). Some typical programming constructs that one might employ in Roomy are: map, reduce, duplicate elimination, chain reduction, pair reduction, and breadth-first search. All aspects of parallelism and remote I/O are hidden within the Roomy library.
Desegregation and Black Dropout Rates

In 1954 the United States Supreme Court ruled that separate schools for black and white children were "inherently unequal." This paper studies whether the desegregation plans of the next 30 years benefited black and white students in desegregated school districts. Data from the 1970 and 1980 censuses suggest desegregation plans of the 1970's reduced high school dropout rates of blacks by two to three percentage points during this decade. No significant change is observed among whites. The results are robust to controls for family income, parental education, and state- and region-specific trends, as well as to tests for selective migration.
Neighborhood conditions, diabetes, and risk of lower-body functional limitations among middle-aged African Americans: A cohort study

The relationship between presence of diabetes and adverse neighborhood and housing conditions and their effect on functional decline is unclear. We examined the association of adverse neighborhood (block face) and housing conditions with incidence of lower-body functional limitations among persons with and those without diabetes using a prospective population-based cohort study of 563 African Americans 49-65 years of age at their 2000-2001 baseline interviews. Participants were randomly sampled African Americans living in the St. Louis area (response rate: 76%). Physician-diagnosed diabetes was self reported at baseline interview. Lower-body functional limitations were self reported based on the Nagi physical performance scale at baseline and the three-year follow-up interviews. The external appearance of the block the respondent lived on and five housing conditions were rated by study interviewers. All analyses were done using propensity score methods to control for confounders. 109 (19.4%) of subjects experienced incident lower-body functional limitations at three-year follow-up. In adjusted analysis, persons with diabetes who lived on block faces rated as fair-poor on each of the five conditions had higher odds (7.79 [95% confidence interval: 1.36-37.55] to 144.6 [95% confidence interval: 4.45-775.53]) of developing lower-body functional limitations than the referent group of persons without diabetes who lived on block faces rated as good-excellent. At least 80 percent of incident lower-body functional limitations was attributable to the interaction between block face conditions and diabetes status. Adverse neighborhood conditions appear to exacerbate the detrimental effects on lower-body functioning associated with diabetes.
Cyclopropene Cycloadditions with Annulated Furans: Total Synthesis of (+)- and (−)-Frondosin B and (+)-Frondosin A

The asymmetric total syntheses of the natural products (+)- and (−)-frondosin B and (+)-frondosin A are reported based on a diastereoselective cycloaddition between tetrabromocyclopropene and an annulated furan to provide a highly functionalized common building block. The bridged bicyclic intermediate could be stereo- and chemoselectively manipulated to produce the two structurally distinct members of the frondosins. Both syntheses feature regioselective palladium-coupling reactions and an unprecedented phosphine-mediated ether bridge cleavage. Surprisingly, the planned enantioselective synthesis of frondosin B led to the opposite epimer of the natural product, suggesting an unusual late stage stereoinversion at C8. Frondosin A, but not frondosin B, was shown to have selective antiproliferative activity against several B-cell lines.
Polyhydroxylated Phenylacrylic Acid Derivatives as New Anti-tumor Agents

Preliminary evidence indicates that antitumor agents containing the o-dihydroxybenzene moiety exhibit enhanced antitumor activity toward malignant cells of high oxidative potential, such as melanoma cells. Based on this consideration, 11 hydroxybenzene acrylic acid derivatives of differing redox potential were prepared as potential substrates for the melanoma specific enzyme tyrosinase, that might exhibit general antitumor activity and enhanced cytotoxicity toward melanoma cells. Five of these compounds [alpha-cyano-beta-(4-hydroxyphenyl)-, alpha-cyano-beta-(3,4-dihydroxyphenyl)-, and alpha-cyano-beta-(3,4,5-trihydroxyphenyl)acrylic acid (THPPA), and 3,4-dihydroxy- and 3,4,5-trihydroxybenzalcyanoacetamide] were found to be substrates for tyrosinase with Km values from 0.08 to 4.13 mM and Vmax values from 0.18 to 3.02. These data indicate that as the number of hydroxy groups increases, the rate of oxidation increases, and that cyanoamides were faster reacting than corresponding cyanoacids, with dicyanides the least reactive. In contrast, cyanoamides were less effective as substrates than cyanoacids. In vitro studies showed all but two compounds were active against L1210 (IC50 range 21-980 microM), SK-MEL-28 (IC50 range 54-950 microM), and SK-MEL-30-3 (IC50 range 54-190 microM). Only THPPA was active in vivo against L1210 and B-16 melanoma.
The Mystery of Capital Formation in Sub-Saharan Africa: Women, Property rights and Customary law

Summary Economists such as Hernando De Soto have argued that clearly defined property rights are essential to capital formation and ultimately to economic growth and poverty alleviation. This article traces two impediments to the clear definition of property rights in the African context: customary law and the status of women. Both of these issues interfere with the attempt of African countries to rearticulate property law with the goal of capital formation. Constructive attempts to define property rights must address the problem of enforcement in under-resourced environments where changes may not be welcomed.
Laparoscopic Liver Resection—Current Update

An increasing number of studies are reporting the outcomes and benefits of laparoscopic liver resection. This article reviews the literature with emphasis on a recent consensus conference on laparoscopic liver resection in 2008, the learning curve for laparoscopic liver surgery, laparoscopic major hepatectomies, oncologic outcomes of laparoscopic liver resection for hepatocellular carcinoma and colorectal cancer liver metastases, and the comparative benefits of laparoscopic versus open liver resection. Current evidence suggests that minimally invasive hepatic resection is safe and feasible with short-term benefits, no economic disadvantage, and no compromise to oncologic principles.
Atomic structure of heterophase interfaces

Abstract High-resolution electron microscopy (HREM) has been used to study internal interfaces between dissimilar materials, notably ceramic-metal interfaces. Structures observed for systems with small and large misfits are compared in metal-metal, metal-ceramic, and ceramic-ceramic boundaries. The interfaces were prepared by a variety of techniques, including internal reduduction, internal oxidation, and epitaxial growth by MOCVD and special thin-film techniques. While interfaces produced by internal oxidation and reduction in f.c.c. systems typically form boundaries on (111) planes, non-equilibrium boundaries have also been generated using special thin film techniques. All boundaries can be characterized by their tendency to form coherent structures. While it appears that the amount of misfit and the bond strength primarily determine the degree of coherency, kinetic factors and substrate defects also seem to play an important role in determining the local defect structure at the boundary and the type of misfit localization.
D3-branes on partial resolutions of abelian quotient singularities of Calabi–Yau threefolds

Abstract We investigate field theories on the world-volume of a D3-brane transverse to partial resolutions of a Z 3 × Z 3 Calabi–Yau threefold quotient singularity. We deduce the field content and Lagrangian of such theories and present a systematic method for mapping the moment map levels characterizing the partial resolutions of the singularity to the Fayet–Iliopoulos parameters of the D-brane world-volume theory. As opposed to the simpler cases studied before, we find a complex web of partial resolutions and associated field-theoretic Fayet–Iliopoulos deformations. The analysis is performed by toric methods, leading to a structure which can be efficiently described in the language of convex geometry. For the world-volume theory, the analysis of the moduli space has an elegant description in terms of quivers. As a by-product, we present a systematic way of extracting the birational geometry of the classical moduli spaces, thus generalizing previous work on resolution of singularities by D-branes.
Knowledge-based query expansion to support scenario-specific retrieval of medical free text

In retrieving medical free text, users are often interested in answers pertinent to certain scenarios that correspond to common tasks performed in medical practice, e.g., treatment or diagnosis of a disease. A major challenge in handling such queries is that scenario terms in the query (e.g., treatment) are often too general to match specialized terms in relevant documents (e.g., chemotherapy). In this paper, we propose a knowledge-based query expansion method that exploits the UMLS knowledge source to append the original query with additional terms that are specifically relevant to the query's scenario(s). We compared the proposed method with traditional statistical expansion that expands terms which are statistically correlated but not necessarily scenario specific. Our study on two standard testbeds shows that the knowledge-based method, by providing scenario-specific expansion, yields notable improvements over the statistical method in terms of average precision-recall. On the OHSUMED testbed, for example, the improvement is more than 5% averaging over all scenario-specific queries studied and about 10% for queries that mention certain scenarios, such as treatment of a disease and differential diagnosis of a symptom/disease.
Gold(I)-catalyzed intermolecular hydroarylation of allenes with nucleophilic arenes: scope and limitations

The addition of nucleophilic methoxyarenes to allenes proceeds at room temperature in dichloromethane with a catalytic amount of phosphite-gold(I) precatalyst and silver additive. The addition is regioselective for the allene terminus, and generates E-allylation products without the need for prefunctionalization of the synthons as organometallics or allyl bromides. Coordinating heteroaromatics and sterically hindered allenes do not participate in the reaction.
Diversity of online community activities

Web sites where users create and rate content as well as form links display many long-tailed distributions. Using one such site, Essembly, we propose causal mechanisms to explain these behaviors. Unlike purely descriptive models, our mechanisms use only information available to each user. We find the long-tails arise from large diversity of user activity and qualities of the rated content. The models not only explain overall behavior but also allow estimating the qualities of users and content from their early history on the site.
Biochemical modification of fats by microorganisms: A preliminary survey

Over 100 different strains of bacteria, actinomycetes, fungi and yeasts were incubated at 28 C for five days in the presence of soybean oil. Some soybean oil was consumed by many microorganisms, and some was also hydrolyzed to free fatty acids.Aspergillus oryzae, two different strains ofAmylomyces rouxii andRhizopus oligosporus hydrolyzed the oil completely (95%). The fatty acids fromAspergillus flavus fermentation contained less linolenic acid than the original soybean oil. Lipase was found intra- and extracellularly when microorganisms were grown in the presence of soybean oil.
Electrical power system for low-earth-orbit spacecraft applications

The results of a trade off study to select an electrical power system (EPS) configuration that is best suited for low-Earth-orbit (LEO) spacecraft with various output power capabilities are presented. The selection is based on parameters like weight, volume, and costs of the power system components. Two EPS configurations used for LEO spacecraft, i.e., one using a direct energy transfer (DET) approach, and the other using a peak power transfer (PPT) approach, are described in detail and compared. At a spacecraft power requirement of 800 W or less, it is highly advantageous to choose the PPT approach to the design of an EPS for LEO spacecraft. However, for a spacecraft in higher orbit and/or with higher power requirements, the DET-based power system is the optimum choice.
Jet cooled emission spectra of toluene and the benzyl radical

Abstract Rotationally cooled gas-phase electronic emission spectra of toluene and the benzyl radical were produced with a corona excited supersonic expansion. This is the first observation of relatively large molecules in this source. Most of the observed bands in both toluene ( 1 B 2 → 1 A 1 ) and the benzyl radical ( 2 A 2 → 2 B 2 ) are the result of emission from the lowest vibrational level in the electronic excited state. The toluene vibronic assignments were based on the known infrared and Raman vibrational frequencies, while the benzyl radical assignments were based on comparison with the toluene frequencies and previous benzyl radical studies. The absence of significant hot band emission from the excited electronic states in both toluene and benzyl suggests extensive vibrational cooling in the corona excited supersonic expansion source. Transitions from the second electronic excited state (22B2 → 12B2) in benzyl radical were observed, although greatly reduced in intensity. This 22B2 state is highly mixed with the low-lying vibrations of the 12A2 state. The interaction between these electronic excited states introduces a mechanism that allows electronic quenching to occur during the expansion via collisional removal of vibrational energy.
Surface Vibrational Spectroscopy on Shear-Aligned Poly(tetrafluoroethylene) Films

Sum-frequency vibrational spectroscopy was used to obtain the first surface vibrational spectra of shear-deposited highly oriented poly(tetrafluoroethylene) (PTFE, Teflon) thin films. The surface PTFE chains appeared to lie along the shearing direction. Vibrational modes observed at 1142 and 1204 cm-1 were found to have the E1 symmetry, in support of some earlier analysis in the long-lasting controversy over the assignment of these modes.
Galactic radiation belts

Several decades of observations have failed to resolve the problem of the interpretation of extended extragalactic radio sources1,2. Most current models invoke the ejection of pairs of plasmoids or relativistic electron beams from the parent elliptical galaxy by various mechanisms3–5. As these theories generally predict the relative orientations of the rotation, magnetic and radio source axes, the measurement of position angles provides one test of the proposed models6,7. However, position angle studies6–11 have produced ambiguous and sample-dependent results. While recent analyses6,7 indicate a preference for radio source alignment along the inferred rotation axes of the optical counterparts, other investigations found random distributions of position angle or bimodal distributions with peaks separated by ∼90° (refs 8, 10). One alternative interpretation of extragalactic radio sources that has received little previous consideration, and is considered herein, concerns the possibility that the emission arises from belts of trapped electrons encircling the parent galaxy in the same manner as the Van Allen belts encircle the Earth. This idea seems to have been dismissed primarily because of the absence of ring-shaped or toroidal emission patterns in the radio observations12. The morphology of synchrotron emission patterns from these hypothetical structures, however, has never been investigated in detail.
Perturbations of Roots under Linear Transformations of Polynomials

Let \({\cal P}_n\) be the complex vector space of all polynomials of degree at most n. We give several characterizations of the linear operators \(T:{\cal P}_n\rightarrow{\cal P}_n\) for which there exists a constant C > 0 such that for all nonconstant \(f\in{\cal P}_n\) there exist a root u of f and a root v of Tf with \(|u-v|\leq C\). We prove that such perturbations leave the degree unchanged and, for a suitable pairing of the roots of f and Tf, the roots are never displaced by more than a uniform constant independent on f. We show that such "good" operators T are exactly the invertible elements of the commutative algebra generated by the differentiation operator. We provide upper bounds in terms of T for the relevant constants.
Excursions and Local Limit Theorems for Bessel-like Random Walks

We consider reflecting random walks on the nonnegative integers with drift of order $1/x$ at height $x$. We establish explicit asymptotics for various probabilities associated to such walks, including the distribution of the hitting time of $0$ and first return time to $0$, and the probability of being at a given height at a given time (uniformly in a large range of heights.) In particular, for certain drifts inversely proportional to $x$ up to smaller-order correction terms, we show that the probability of a first return to $0$ at time $n$ decays as a certain inverse power of $n$, multiplied by a slowly varying factor that depends on the drift correction terms.
Mobility patterns in microcellular wireless networks

This study investigates mobility patterns in microcellular wireless networks, based on measurements from the 802.11 based system that blankets the Carnegie Mellon University campus. We characterize the distribution of dwell time, which is the length of time that a mobile device remains in a cell until the next handoff, and sign-on interarrival time, which is the length of time between successive sign-ons from the same mobile device. Many researchers have assumed that these distributions are exponential, but our results based on empirical analysis show that dwell time and sign-on interarrival time can be accurately described using heavy-tailed arithmetic distributions that have infinite mean and variance. We also show that the number of handoffs per sign-on can be modeled accurately with a heavy-tailed distribution.
The Laurent Phenomenon

A composition of birational maps given by Laurent polynomials need not be given by Laurent polynomials; however, sometimes-quite unexpectedly-it does. We suggest a unified treatment of this phenomenon, which covers a large class of applications. In particular, we settle in the affirmative a conjecture of D. Gale and R. Robinson on integrality of generalized Somos sequences, and prove the Laurent property for several multidimensional recurrences, confirming conjectures by J. Propp, N. Elkies, and M. Kleber.