cssi/SciSciGPT-SciSciNet huggingface dataset:
The Evolution of Supernovae in Circumstellar Wind-Blown Bubbles. I. Introduction and One-Dimensional Calculations

Mass loss from massive stars (8 M☉) can result in the formation of circumstellar wind-blown cavities surrounding the star, bordered by a thin, dense, cold shell. When the star explodes as a core-collapse supernova (SN), the resulting shock wave will interact with this modified medium around the star, rather than the interstellar medium. In this work we first explore the nature of the circumstellar medium around massive stars in various evolutionary stages. This is followed by a study of the evolution of SNe within these wind-blown bubbles. The evolution depends primarily on a single parameter Λ, the ratio of the mass of the dense shell to that of the ejected material. We investigate the evolution for different values of this parameter. We also plot approximate X-ray surface brightness plots from the simulations. For very small values Λ 1 the effect of the shell is negligible, as one would expect. Values of Λ 1 affect the SN evolution, but the SN "forgets" about the existence of the shell in about 10 doubling times or so. The remnant density profile changes, and consequently the X-ray emission from the remnant will also change. The initial X-ray luminosity of the remnant is quite low, but interaction of the shock wave with the dense circumstellar shell can increase the luminosity by 2-3 orders of magnitude. As the reflected shock begins to move inward, X-ray images will show the presence of a double-shelled structure. Larger values result in more SN energy being expended to the shell. The resulting reflected shock moves quickly back to the origin, and the ejecta are thermalized rapidly. The evolution of the remnant is speeded up, and the entire remnant may appear bright in X-rays. If Λ 1, then a substantial amount of energy may be expended in the shell. In the extreme case the SN may go directly from the free expansion to the adiabatic stage, bypassing the Sedov stage. Our results show that in many cases the SNR spends a significant amount of time within the bubble. The low density within the bubble can delay the onset of the Sedov stage and may end up reducing the amount of time spent in the Sedov stage. The complicated density profile within the bubble makes it difficult to infer the mass-loss properties of the pre-SN star by studying the evolution of the resulting SNR.
N = 2 Superstrings with (1,2m) Spacetime Signature

Abstract We show that the N =2 superstring in d =2 D ⩾6 real dimensions, with criticaly achieved by including background charges in the two real time directions, exhibits a “coordinate-freezing” phenomenon, whereby the momentum in one of the two time directions is constrained to take a specific value for each physical state. This effectively removes this time direction as a physical coordinate, leaving the theory with (1, d −2) real spacetime signature. Norm calculations for low-lying physical states suggest that the theory is ghost free.
TRANSPORT PROCESSES AND INTERFACIAL PHENOMENA IN AN EVAPORATING MENISCUS

Abstract The chemical potential of an extended meniscus on an inclined flat plate is a function of its temperature, curvature, film thickness and height above a reference level. The meniscus thickness profile, which is related to the stress field in the liquid, was used to measure the sensitivity of the meniscus to the non-equilibrium effects associated with evaporation/condensation. The thickness profiles of a completely wetting film of a 1,1,2-Trichlorotrifluoroethane were measured using microcomputer based image processing of interferometric images. The automated data acquisition procedures were used to achieve enhanced resolution and thereby a better understanding of the transport processes occurring in the contact line region. The interfacial properties of the system were initially evaluated in situ and then used to describe the transport processes associated with a heated meniscus. Consistent with theoretical models, the curvature increased very rapidly from a value of zero in the adsorbed film at t...
The Expected Redshift Distribution of Gamma-Ray Bursts

We predict the redshift distribution of gamma-ray bursts (GRBs), assuming that they trace the cosmic star formation history. We find that a fraction 50% of all GRBs on the sky originate at a redshift z 5, even though the fraction of the total stellar mass formed by z ~ 5 is only ~15%. These two fractions are significantly different, because they involve different cosmological factors when integrating the star formation rate over redshift. Hence, deep observations of transient events, such as GRB afterglows or supernovae, provide an ideal strategy for probing the high-redshift universe. We caution, however, that existing or planned flux-limited instruments are likely to detect somewhat smaller fractions of high-redshift bursts. For example, we estimate that the fraction of all bursts with redshifts z 5 is ~10% in the case of the BATSE instrument and ~25% in the case of Swift. We also show that the intrinsic distribution of GRB durations is bimodal but significantly narrower and shifted toward shorter durations than the observed distribution.
The influence of preoperative MRI on breast cancer treatment.

Background Breast magnetic resonance imaging (MRI) is increasingly used for breast cancer treatment planning. The aim of this study was to evaluate rates of mastectomy and breast-conserving surgery (BCS) in patients who undergo preoperative MRI.
Network approximation of input-output maps and functionals

We give results concerning the problem of approximating the input-output maps of nonlinear discrete-time approximately finite-memory systems. Here the focus is on the linear dynamical parts of the approximating structures, and we give examples showing that these linear parts can be derived from asingle prespecified function that meets certain conditions. This is done in the context of an approximation theorem in which attention is focused on what we call "basic sets." We also consider the related but very different problem of approximating nonlinear functionals using lattice operations or the usual linear ring operations. For this problem we give criteria, not just sufficient conditions, for approximation on compact subsets of reflexive Banach spaces (any Hilbert space is a reflexive Banach space).
The Local Space Density of Dwarf Galaxies

We estimate the luminosity function of field galaxies over a range of 10 mag (-22<MBJ<-12 for H0 = 100 km s-1 Mpc-1) by counting the number of faint APM galaxies around Stromlo-APM redshift survey galaxies at known distance. The faint end of the luminosity function rises steeply at MBJ ≈ -15, implying that the space density of dwarf galaxies is at least 2 times larger than predicted by a Schechter function with flat faint-end slope. Such a high abundance of dwarf galaxies at low redshift can help explain the observed number counts and redshift distributions of faint galaxies without invoking exotic models for galaxy evolution.
Pattern Based Prediction for Plasma Etch

Plasma etching is a key process for pattern formation in integrated circuit (IC) manufacturing. Unfortunately, pattern-dependent nonuniformities arise in plasma etching processes due to localized microloading and feature size or aspect ratio-dependent reactive ion etch lag. We propose a semi-empirical methodology for characterization and chip-scale modeling of pattern-dependent effects in plasma etching of ICs. We apply this methodology to the study of interconnect trench etching and show that an integrated model is able to predict both pattern density and feature size dependent nonuniformities in trench depth
The effect of intraoral suction on oxygen-enriched surgical environments: a mechanism for reducing the risk of surgical fires

In this study, a mechanical model was applied in order to replicate potential surgical fire conditions in an oxygen-enriched environment with and without high-volume suction typical for dental surgical applications. During 41 trials, 3 combustion events were measured: an audible pop, a visible flash of light, and full ignition. In at least 11 of 21 trials without suction, all 3 conditions were observed, sometimes with an extent of fire that required early termination of the experimental trial. By contrast, in 18 of 20 with-suction trials, ignition did not occur at all, and in the 2 cases where ignition did occur, the fire was qualitatively a much smaller, candle-like flame. Statistically comparing these 3 combustion events in the no-suction versus with-suction trials, ignition (P = .0005), audible pop (P = .0211), and flash (P = .0092) were all significantly more likely in the no-suction condition. These results suggest a possible significant and new element to be added to existing surgical fire safety protocols toward making surgical fires the "never-events" they should be.
On the Quantization of Zero-Weight Super Dynamical R-Matrices

Solutions of the classical dynamical Yang-Baxter equation on a Lie superalgebra are called super dynamical r-matrices. A super dynamical r-matrix r satisfies the zero weight condition if [h⊗ 1 + 1⊗ h, r(λ)] = 0 for all h ∈ h, λ ∈ h∗. In this paper we explicitly quantize zero-weight super dynamical r-matrices with zero coupling constant for the Lie superalgebra gl(m,n). We also answer some questions about super dynamical R-matrices. In particular, we prove a classification theorem and offer some support for one particular interpretation of the super Hecke condition.
Charge stripes in cuprate superconductors: The middle way

Charge and spin stripe order is a type of electronic crystal observed in certain layered cuprates associated with high-temperature superconductivity. Quantum-disordered stripes could be relevant for understanding the superconductivity. Here I discuss recent experimental characterizations of the stripe-ordered state in La 1.875 Ba 0.125 CuO 4 , and compare them with properties of superconducting compositions.
Synthesis of timed asynchronous circuits

The authors present a systematic procedure for synthesizing timed asynchronous circuits using timing constraints dictated by system integration, thereby facilitating natural interaction between synchronous and asynchronous circuits. Their timed circuits also tend to be more efficient, in both speed and area, compared with traditional asynchronous circuits. The synthesis procedure begins with a cyclic graph specification to which timing constraints can be added. First, the cyclic graph is unfolded into an infinite acyclic graph. Then, an analysis of two finite subgraphs of the infinite acyclic graph detects and removes redundancy in the original specification based on the given timing constraints. From this reduced specification, an implementation that is guaranteed to function correctly under the timing constraints is systematically synthesized. With practical circuit examples, it is demonstrated that the resulting timed implementation is significantly reduced in complexity compared with implementations previously derived using other methodologies. >
US experience with doctors and patients sharing clinical notes.

The move to offer patients online access to their clinicians’ notes is accelerating and holds promise of supporting more truly collaborative relationships between patients and clinicians, say Jan Walker , Michael Meltsner , and Tom Delbanco
Moral Leadership: Ancient Lessons for Modern Times

The Bible does not hide mistakes made by great people. This makes it an extremely valuable text for teaching moral character. In fact, the lessons learned from mistakes often provide a more lasting...
Synthesis, structure, and magnetic and electronic properties of Cs2Hg2USe5

The compound Cs{sub 2}Hg{sub 2}USe{sub 5} was obtained from the solid-state reaction of U, HgSe, Cs{sub 2}Se{sub 3}, Se, and CsI at 1123 K. This material crystallizes in a new structure type in space group P2/n of the monoclinic system with a cell of dimensions a=10.276(6) A, b=4.299(2) A, c=15.432(9) A, beta=101.857(6) A, and V=667.2(6) A{sup 3}. The structure contains {sub i}nfinity{sup 2}[Hg{sub 2}USe{sub 5}] layers separated by Cs atoms. Within the layers are distorted HgSe{sub 4} tetrahedra and regular USe{sub 6} octahedra. In the temperature range of 25-300 K Cs{sub 2}Hg{sub 2}USe{sub 5} displays Curie-Weiss paramagnetism with mu{sub eff}=3.71(2) mu{sub B}. The compound exhibits semiconducting behavior in the [010] direction; the conductivity at 298 K is 3x10{sup -3} S/cm. Formal oxidation states of Cs/Hg/U/Se may be assigned as +1/+2/+4/- 2, respectively. - Graphical abstract: View of the crystal structure of Cs{sub 2}Hg{sub 2}USe{sub 5}.
Quantum geometry of the universal hypermultiplet

The universal hypermultiplet moduli space metric in the type-IIA superstring theory compactified on a Calabi-Yau threefold is related to integrable systems. The instanton corrections in four dimensions arise due to multiple wrapping of BPS membranes and fivebranes around certain (supersymmetric) cycles of Calabi-Yau. The exact (non-perturbative) metrics can be calculated in the special cases of (i) the D-instantons (or the wrapped D2-branes) in the absence of fivebranes, and (ii) the fivebrane instantons with vanishing charges, in the absence of D-instantons. The solutions of the first type are governed by the three-dimensional Toda equation, whereas the solutions of the second type are governed by the particular Painleve VI equation.
Scope and Mechanism of Formal SN2′ Substitution Reactions of a Monomeric Imidozirconium Complex with Allylic Electrophiles

The zirconium imido complex Cp2(THF)ZrNSi(t−Bu)Me2 (1) reacts with allylic ethers, chlorides, and bromides to give exclusively the products of the SN2‘ reaction; i.e., attack at the allylic position remote from the leaving group with migration of the double bond. The primary amine products can be isolated in excellent yields, after in situ Cbz protection, in the presence of variety of functional groups. Good diastereoselectivity and complete stereoselectivity allowed the formation of enantioenriched allylic amines from enantioenriched allylic ethers. Regiospecific substitution with 1 has also been achieved with allylic fluorides, which are notoriously poor substrates in other substitution reactions. On the basis of rate and kinetic isotope effect studies, we propose a general mechanism for the allylic substitution reactions with 1 which involves dissociation of THF and binding of the substrate, followed by the substitution step. In a DFT study of the substitution reaction, we identified a six-membered clo...
Automatic vehicle monitoring applied to bus operations

The proximity type of automatic vehicle-monitoring system now being demonstrated by the Chicago Transit Authority, Chicago, Ill., will be described. Details of system configuration, communication links, and computer requirements will be described.
Pulsed Laser Deposition and Characterization of Crystalline Lithium Cobalt Dioxide ( LiCoO2 ) Thin Films

The pulsed laser deposition of LiCoO 2 and LiCo 0.5 Al 0.5 O 2 thin films was investigated as a function of deposition conditions. The initial growth process optimization focused on films grown on (200)-textured SnO 2 -coated glass substrates. Film growth was also investigated on ZnO and indium-tin oxide (ITO) coated substrates. For both LiCoO 2 and LiCo 0.5 Al 0.5 O 2 , dense uniaxially textured (003)-oriented films of the layered LiCoO 2 phase were grown on the SnO 2 coated substrates. The grain size increased substantially with increased substrate temperature in the range from 400 to 700°C. For constant current cycling between 3.5 and 4.4 V vs. Li, the best crystalline LiCoO 2 films, grown at T s = 700°C, p O2 = 2000 mTorr, had an initial discharge capacity of ∼118 8 mAh/g (0.43 Li/Co) which decreased ∼0.5% per cycle. For LiCo 0.5 Al 0.5 O 2 , although, as predicted, the films did have a higher cathode potential, the charge capacity was signilicantly lower than that for LiCoO 2 films, Finally, functional LiCoO 2 thin film cathodes were grown on flexible ITO-coated Upilex polymer substrates at T s = 300°C.
Atomic Layer Deposition of Metal Oxides on Pristine and Functionalized Graphene

We investigate atomic layer deposition (ALD) of metal oxide on pristine and functionalized graphene. On pristine graphene, ALD coating can only actively grow on edges and defect sites, where dangling bonds or surface groups react with ALD precursors. This affords a simple method to decorate and probe single defect sites in graphene planes. We used perylene tetracarboxylic acid (PTCA) to functionalize the graphene surface and selectively introduced densely packed surface groups on graphene. Uniform ultrathin ALD coating on PTCA graphene was achieved over a large area. The functionalization method could be used to integrate ultrathin high-κ dielectrics in future graphene electronics.
Infrastructure and climate change: a study of impacts and adaptations in Malawi, Mozambique, and Zambia

The African Development Bank has called for $40 Billion USD per year over the coming decades to be provided to African countries to address development issues directly related to climate change. The current study addresses a key component of these issues, the effect of climate change on the road infrastructure of Malawi, Mozambique, and Zambia. The study incorporates a stressor-response approach to estimate the effects of projected precipitation, temperature, and flooding changes on the paved and unpaved road infrastructure of these countries. The paper highlights the result of running 425 climate scenarios for each road type and policy option from 2010 to 2050. Based on this broad analysis, it is estimated that the three southern African countries are facing a potential $596 million price tag based on median climate scenarios to maintain and repair roads as a result of damages directly related to temperature and precipitation changes from potential climate change through 2050. The challenge for policy makers is to determine the potential risk that a country is facing based on the uncertainties associated with the multiple aspects of climate change modeling.
High-speed transistor computer circuit design

The realization of the computer described by S. W. Dunwell calls for high-frequency circuits capable of passing a signal through five sequential logical stages in 100 millimicroseconds. At the start of the project a study of available devices and techniques indicated that this goal would be difficult to reach without significant improvements either in the devices or the circuits, or both. Such an improvement came about in the device area with the availability of drift type transistors for research work. The characteristics of these transistors made necessary a new approach to circuit design which has resulted in circuits which not only meet the speed requirements, but also are relatively simple, reliable, and insensitive to noise.
A 105km reach fully passive 10G-PON using a novel digital OLT

A truly passive long-reach 10G-TDM-PON using digital OLT is demonstrated through 105km SSMF and 1:128 splitting with 5dB margin (51dB loss budget). The analog transceivers at the ONUs still maintain low system complexity and cost.
Message passing on the QCDSP supercomputer

Abstract The QCDSP machines were designed for lattice gauge calculations. For planning it is crucial to explore this architecture for other computationally intensive tasks. Here I describe an implementation of a simple message passing scheme. With the objective being simplicity, I introduce a small number of generic functions for manipulating a large data set spread over the machine. I test the scheme on three applications: a fast Fourier transform, arbitrary dimension SU(N) pure lattice gauge theory, and the manipulation of Fermionic Fock states through a distributed hash table. These routines compile both on QCDSP and a Unix workstation.
A concise synthesis of the molecular framework of pleuromutilin

Two syntheses of the tricyclic carbon skeleton of pleuromutilin are reported. Diastereoselective 1,4-conjugate additions were used to elaborate bicyclic precursors at an early stage of each route, while ring-forming olefin metatheses were executed to complete the pleuromutilin carbon framework. The congeners prepared are appropriately functionalized to enable access to diverse pleuromutilin analogues.
Decomposing the Boundary of a Nonconvex Polyhedron

We show that the boundary of a three-dimensional polyhedron withr reflex angles and arbitrary genus can be subdivided intoO(r) connected pieces, each of which lies on the boundary of its convex hull. A remarkable feature of this result is that the number of these convex-like pieces is independent of the number of vertices. Furthermore, it is linear inr, which contrasts with a quadratic worst-case lower bound in the number of convex pieces needed to decompose the polyhedron itself. The number of new vertices introduced in the process isO(n). The decomposition can be computed inO(n+rlogr) time.
Synthesis of oxabetweenallenes

Abstract A new route to heterocyclic doubly bridged allenes has been developed starting from cycloalkynones. Addition of 4-pentenylmagnesium bromide followed by acetylation and SN2′ addition of 4-pentenylmagnesium bromide-CuI affords symmetrically substituted cycloallenes. Selective hydroboration-oxidation of the terminal alkenes followed by phase-transfer promoted cyclization of the monotosylate derivatives yields the oxabetweenallenes.
Exchange reactions between trimethylsilyl azide and hexamethyldigermoxane

Abstract Trimethylsilyl azide and hexamethyldigermoxane undergo exchange at room temperature to stoichiometrically yield trimethyl(trimethylsiloxy)germane and trimethylgermyl azide. The rates of this second order reaction have been measured at several temperatures between 21 and 53° C. An Arrhenius plot of this data gives the following activation parameters: ΔS‡ = −40 ± 2 eu. The large negative entropy of activation implies a highly ordered transition state for this reactions.
Nonreference medical image edge map measure

Edge detection is a key step in medical image processing. It is widely used to extract features, perform segmentation, and further assist in diagnosis. A poor quality edge map can result in false alarms and misses in cancer detection algorithms. Therefore, it is necessary to have a reliable edge measure to assist in selecting the optimal edge map. Existing reference based edge measures require a ground truth edge map to evaluate the similarity between the generated edge map and the ground truth. However, the ground truth images are not available for medical images. Therefore, a nonreference edge measure is ideal for medical image processing applications. In this paper, a nonreference reconstruction based edge map evaluation (NREM) is proposed. The theoretical basis is that a good edge map keeps the structure and details of the original image thus would yield a good reconstructed image. The NREM is based on comparing the similarity between the reconstructed image with the original image using this concept. The edge measure is used for selecting the optimal edge detection algorithm and optimal parameters for the algorithm. Experimental results show that the quantitative evaluations given by the edge measure have good correlations with human visual analysis.
Assessing the credibility of instrumental variables inference with imperfect instruments via sensitivity analysis

Consistent instrumental variables (IV) estimation requires instruments uncorrelated with the model errors, but this assumption is usually both suspect and untestable. Here the asymptotic sampling distribution of the IV parameter estimator is derived for any specified instrument-error covariance vector. This result makes it possible to quantify the sensitivity of any particular IV inference result to instrument-error correlations, allowing one to assess the robustness of such inferential conclusions to uncertainty in the validity of the instruments. An application illustrating the value of this sensitivity analysis is given to a study by Acemoglu et al. (2001).
Fast food prices, obesity, and the minimum wage

Recent proposals argue that a fast food tax may be an effective policy lever for reducing population weight. Although there is growing evidence for a negative association between fast food prices and weight among adolescents, less is known about adults. That any measured relationship to date is causal is unclear because there has been no attempt to separate variation in prices on the demand side from that on the supply side. We argue that the minimum wage is an exogenous source of variation in fast food prices, conditional on income and employment. In two-stage least-squares analyses, we find little evidence that fast food price changes affect adult BMI or obesity prevalence. Results are robust to including controls for area and time fixed effects, area time trends, demographic characteristics, substitute prices, numbers of establishments and employment in related industries, and other potentially related factors.
The boundary problem in democratic theory: why the demos should be bounded by the state

Democracy is rule by the demos, but by what criteria is the demos constituted? Theorists of democracy have tended to assume that the demos is properly defined by national boundaries or by the territorial boundaries of the modern state. In a recent turn, many democratic theorists have advanced the principles of affected interests and coercion as the basis for defining the boundaries of democracy. According to these principles, it is not co-nationals or fellow citizens but all affected or all subjected to coercion who constitute the demos. In this paper, I argue that these recent approaches to the boundary problem are insufficiently attentive to the conditions of democracy. Democracy is not merely a set of procedures; it also consists of substantive values and principles. Political equality is a constitutive condition of democracy, and solidarity is an instrumental condition of democracy. The affected interests and coercion principles create serious problems for the realization of these conditions – problems of size and stability. Building on this critique, this paper presents democratic considerations for why the demos should be bounded by the territorial boundaries of the state, grounded in the state's role in (1) securing the constitutive conditions of democracy, (2) serving as the primary site of solidarity conducive to democratic participation, and (3) establishing clear links between representatives and their constituents. I examine and reject a third alternative, a global demos bounded by a world state, and conclude by considering some practical implications of my argument.
The Use of Management Control Mechanisms to Mitigate Moral Hazard in the Decision to Outsource

Using archival data from the U.S. passenger airline industry, this study examines whether management control mechanisms aimed at mitigating moral hazard explain outsourcing decisions over and above transaction cost economics (TCE) determinants documented in prior research. Consistent with TCE theory, we find that in-house production efficiencies and our proxy for transaction risk (i.e., deriving from transaction infrequency, transaction complexity, and relationship-specific investments) significantly explain the extent of outsourcing of aircraft maintenance. We extend TCE insights to show that incentive delta (i.e., the sensitivity of CEO portfolio holdings to stock price changes) strengthens the negative association between production efficiencies and outsourcing while incentive vega (i.e., the sensitivity of CEO holdings to stock return volatility) weakens the negative association between transaction risk and outsourcing. Monitoring strengthens the negative association between in-house production efficiencies and outsourcing, but has no effect on the transaction risk–outsourcing relation. The results suggest that the use of outsourcing to achieve cost savings is promoted through both incentive contracts and monitoring, but outsourcing to achieve the desired risk level is promoted only through incentive contracts.
Are we overestimating REIT idiosyncratic risk? Analysis of pricing effects and persistence

Abstract This study uses a multifactor REIT-specific model to estimate and compare REIT idiosyncratic volatility vis-a-vis the same from the Fama–French three-factor model. Estimates of conditional idiosyncratic volatility and conditional betas obtained from a multifactor REIT-returns model and a bivariate EGARCH model respectively are found to be positively and significantly related with REIT returns. Consistent with Merton's (1987) predictions, we observe that larger REITs post higher average returns when idiosyncratic risk is introduced in cross-sectional regressions. Persistence of past market-risk does not appear to be short-lived and seems to have a lasting impact on future idiosyncratic volatility. We also observe mild evidence of persistence of past idiosyncratic risk, albeit short-lived, thereby suggesting that past idiosyncratic risk has a short-term impact on future idiosyncratic risk.
Inversion of multivariable linear systems

A new algorithm for constructing an inverse of a multivariable linear dynamical system is presented. This algorithm, which is considerably more efficient than previous methods, also incorporates a relatively simple criterion for determining if an inverse system exists. New insight into the structure of a system inverse is gained by consideration of the inverse system representations resulting from the algorithm. A precise bound on the number of output differentiations required is obtained as well as a bound on the total number of integrators and differentiators necessary to realize the inverse. This latter bound is equal to the order of the original system. A further advantage of the algorithm and theory developed is that it is applicable to both time-invariant systems and time-variable systems which satisfy certain regularity conditions. One application is also given: a complete description of the set of initial states necessary and sufficient for a specified function to be the output of an invertible system.
Magnetic fields within color superconducting neutron star cores

We discuss the Meissner effect for a color superconductor formed by cold dense quark matter. Though color and ordinary electromagnetism are broken in a color superconductor, there is a linear combination of the photon and a gluon that remains massless. Consequently, a color superconducting region may be penetrated by an external magnetic field. We show that at most a small fraction of the magnetic field is expelled, and if the screening distance is the smallest length scale in the problem there is no expulsion at all. We calculate the behavior of the magnetic field for a spherical geometry relevant for compact stars. If a neutron star contains a quark matter core, this core is a color superconductor. Our results demonstrate that such cores admit magnetic fields without restricting them to quantized flux tubes. Such magnetic fields within color superconducting neutron star cores are stable on time scales longer than the age of the universe, even if the spin period of the neutron star is changing.
Trajectory economics: Assessing the flow of ecosystem services from coastal restoration

Abstract Monetized estimates of ecosystem services are increasingly cited as partial justification for a wide range of environmental restoration initiatives, yet parallel applications of these values in performance assessment have been limited. Incorporated into traditional economic models, such values can offer potential insight on programmatic efficiency and help to inform policy tradeoffs within and between competing methods. For this analysis, acreage trajectories and cost functions are developed for dredge- and diversion-based land reclamation methods in coastal Louisiana, USA. Benefit–cost models are constructed from which ecosystem service values are initially derived via break-even analysis and then specified to inform comparative case studies. Results indicate that the minimum service value required to offset project expenditures is typically higher for “natural” diversion-based restoration relative to “rapid” dredge-based methods under historic project conditions. Accounting for climatological and socioeconomic risks widens this gap, with benefit–cost ratios for dredge-based reclamation exceeding that of diversions in 16 benefit–cost simulations conducted over a 50-year project horizon. Taken together, these results highlight the influence of time and risk in the assessment of competing project alternatives, and suggest the need to reframe restoration efficiency in terms of the aggregate flow of ecosystem services, versus the per unit costs of terminal stocks.
The impact of stock market information production on internal resource allocation

Abstract We analyze the resource allocation decision of a manager inside a multidivision firm whose compensation is based on the firm's stock price. We find that internal investments exhibit a positive correlation across the firms divisions. Namely, when two single-division firms merge the optimal investment level in one division becomes more positively related to the investment level in the other division. In addition, following a spinoff, divisional investments decline (increase) whenever the separated division has a project with a low (high) Sharpe ratio. Finally, multidivision firms trade at a discount which is larger the more diverse the investment sets of the divisions.
Metalated Nitriles: Internal 1,3-Asymmetric Induction

Stereoselective alkylations of acyclic, metalated nitriles are intimately controlled by a remote stereocenter. Probing the optimal steric demand through alkylations with a series of substituted pentanenitriles reveal the fundamental requirements for 1,3-asymmetric induction. Relaying these requirements into a predictive model suggests that the stereoselectivity arises from a preferential electrophilic attack on the more stable diamond lattice conformation of the metalated nitrile. Using this strategy a series of metalated alkanenitriles selectively intercept a diverse range of electrophiles in alkylations that efficiently install new quaternary centers. The metalated nitrile alkylations provide fundamental insight for remote stereoinduction and a solid foundation for further advances in stereoselective alkylations of flexible nucleophiles having a defined shape.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
SIR dynamics in random networks with heterogeneous connectivity

Random networks with specified degree distributions have been proposed as realistic models of population structure, yet the problem of dynamically modeling SIR-type epidemics in random networks remains complex. I resolve this dilemma by showing how the SIR dynamics can be modeled with a system of three nonlinear ODE’s. The method makes use of the probability generating function (PGF) formalism for representing the degree distribution of a random network and makes use of network-centric quantities such as the number of edges in a well-defined category rather than node-centric quantities such as the number of infecteds or susceptibles. The PGF provides a simple means of translating between network and node-centric variables and determining the epidemic incidence at any time. The theory also provides a simple means of tracking the evolution of the degree distribution among susceptibles or infecteds. The equations are used to demonstrate the dramatic effects that the degree distribution plays on the final size of an epidemic as well as the speed with which it spreads through the population. Power law degree distributions are observed to generate an almost immediate expansion phase yet have a smaller final size compared to homogeneous degree distributions such as the Poisson. The equations are compared to stochastic simulations, which show good agreement with the theory. Finally, the dynamic equations provide an alternative way of determining the epidemic threshold where large-scale epidemics are expected to occur, and below which epidemic behavior is limited to finite-sized outbreaks.
The rotation class of a flow

Abstract Generalizing a construction of A. Weil, we introduce a topological invariant for flows on compact, connected, finite dimensional, Abelian, topological groups. We calculate this invariant for some examples.
Novel Diagnostic and Prognostic Modalities in Inflammatory Bowel Disease

Inflammatory bowel disease remains a complex disease with variable clinical presentations and often nonspecific symptoms. Physicians must rely on diagnostic tools for clarification of disease diagnosis and for guiding management of patients with established disease. Advances in radiologic imaging modalities facilitate early and accurate detection of luminal disease and extraluminal complications. The introduction and dissemination of small bowel capsule endoscopy and double-balloon enteroscopy permit detailed visualization and sampling of the mucosa throughout the entire bowel. Serologic biomarkers are evolving as a valuable tool to clarify diagnosis and stratify patients by disease phenotypes and patterns of behavior. Neutrophil-derived fecal biomarkers are emerging as useful surrogate markers of intestinal inflammation with the potential for a variety of clinical applications, but their application to clinical management has not yet been clarified.
Markov decision processes

Abstract A review is given of an optimization model of discrete-stage, sequential decision making in a stochastic environment, called the Markov decision process (MDP). This review presents an overview of theoretical and computational results, applications, several generalizations of the standard MDP problem formulation, and future directions for research. The reference list contains seminal papers, key texts, and surveys for the interested reader.
The real exchange rate and US manufacturing profits: a theoretical framework with some empirical support

This paper studies the relationship between the real exchange rate and manufacturing profits using Marston's model of pricing-to-market. Looking at US data, we find that a sustained real depreciation of the dollar has a significant and substantial influence on manufacturing profits. During the early 1980s, the appreciation of the dollar reduced profits by at least 25% conditional on the realized time path of sales, costs, and the US markup. The post-plaza depreciation of the dollar boosted profits at least 30%. © 1997 John Wiley & Sons, Ltd.
Integrase Inhibitors Effective against Human T-Cell Leukemia Virus Type 1

Drugs targeting the viral enzyme integrase have been in use for several years as part of the treatment regimen for patients with human immunodeficiency virus type 1 (HIV-1), and similar classes of compounds have been shown to inhibit human T-cell leukemia virus type 1 (HTLV-1) integration in vitro. The current study shows that the clinically approved HIV-1 integrase inhibitor, raltegravir, as well as the more recent diketo acid derivative, MK-2048, are active inhibitors of HTLV-1 infection in vitro. These agents were effective in inhibiting cell-free and cell-to-cell transmission of HTLV-1 in lymphoid and nonlymphoid cells. The drugs also inhibited HTLV-1 immortalization of human peripheral blood mononuclear cells. A novel adaptation of the Alu assay for viral integration was used to show that the drugs inhibit viral integration without affecting reverse transcription. These data support the administration of raltegravir and other integrase inhibitors as treatments for patients with HTLV-1-associated diseases.
Should Latin America Save More to Grow Faster

A widely shared view holds that there is no policy-exploitable causal connection from saving to growth because domestic saving is fully endogenous, optimally determined, or substitutable by foreign saving. Yet, abandoning these assumptions, which are questionable in the real world of frictions, leads to three channels through which domestic saving may promote growth: a real interest rate channel, whereby saving reduces the cost of capital (the sovereign risk premium) and enhances macro sustainability; a real exchange rate channel, through which saving leads to a more competitive real exchange rate; and an endogenous saving channel, whereby saving follows growth but in a less than perfectly elastic manner, thereby amplifying the effects of the first two channels. Broad-based econometric evidence supports all three channels and suggests that Latin America, a historically low growth-low saving region, would benefit from boosting its saving rate, especially in countries with recurrently weak balance of payments and persistent domestic demand pressures on the non-tradable sector.
Uncertainty and Risk in Financial Markets

This paper considers a general equilibrium model in which the distinction between uncertainty and risk is formalized by assuming agents have incomplete preferences over statecontingent consumption bundles, as in Bewley (1986). Without completeness, individual decision making depends on a set of probability distributions over the state space. A bundle is preferred to another if and only if it has larger expected utility for all probabilities in this set. When preferences are complete this set is a singleton, and the model reduces to standard expected utility. In this setting, we characterize Pareto optima and equilibria, and show that the presence of uncertainty generates robust indeterminacies in equilibrium prices and allocations for any specification of initial endowments. We derive comparative statics results linking the degree of uncertainty with changes in equilibria. Despite the presence of robust indeterminacies, we show that equilibrium prices and allocations vary continuously with underlying fundamentals. Equilibria in a standard risk economy are thus robust to adding small degrees of uncertainty. Finally, we give conditions under which some assets are not traded due to uncertainty aversion.
A General Framework for Scalability and Performance Analysis of DHT Routing Systems

In recent years, many DHT-based P2P systems have been proposed, analyzed, and certain deployments have reached a global scale with nearly one million nodes. One is thus faced with the question of which particular DHT system to choose, and whether some are inherently more robust and scalable. Toward developing such a comparative framework, we present the reachable component method (RCM) for analyzing the performance of different DHT routing systems subject to random failures. We apply RCM to five DHT systems and obtain analytical expressions that characterize their routability as a continuous function of system size and node failure probability. An important consequence is that in the large-network limit, the routability of certain DHT systems go to zero for any non-zero probability of node failure. These DHT routing algorithms are therefore unscalable, while some others, including Kademlia, which powers the popular eDonkey P2P system, are found to be scalable.
Selective gas adsorption and separation in metal–organic frameworks

Adsorptive separation is very important in industry. Generally, the process uses porous solid materials such as zeolites, activated carbons, or silica gels as adsorbents. With an ever increasing need for a more efficient, energy-saving, and environmentally benign procedure for gas separation, adsorbents with tailored structures and tunable surface properties must be found. Metal–organic frameworks (MOFs), constructed by metal-containing nodes connected by organic bridges, are such a new type of porous materials. They are promising candidates as adsorbents for gas separations due to their large surface areas, adjustable pore sizes and controllable properties, as well as acceptable thermal stability. This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorption in rigid and flexible MOFs. Based on possible mechanisms, selective adsorptions observed in MOFs are classified, and primary relationships between adsorption properties and framework features are analyzed. As a specific example of tailor-made MOFs, mesh-adjustable molecular sieves are emphasized and the underlying working mechanism elucidated. In addition to the experimental aspect, theoretical investigations from adsorption equilibrium to diffusion dynamics via molecular simulations are also briefly reviewed. Furthermore, gas separations in MOFs, including the molecular sieving effect, kinetic separation, the quantum sieving effect for H2/D2 separation, and MOF-based membranes are also summarized (227 references).
Use of robust classification techniques for the prediction of human cytochrome P450 2D6 inhibition.

A new in silico model is developed to predict cytochrome P450 2D6 inhibition from 2D chemical structure. Using a diverse training set of 100 compounds with published inhibition constants, an ensemb...
An assessment of differences between cloud effective particle radius retrievals for marine water clouds from three MODIS spectral bands

The Moderate Resolution Imaging Spectroradiometer (MODIS) cloud product provides three separate 1 km resolution retrievals of cloud particle effective radii (r (sub e)), derived from 1.6, 2.1 and 3.7 micron band observations. In this study, differences among the three size retrievals for maritime water clouds (designated as r (sub e), 1.6 r (sub e), 2.1 and r (sub e),3.7) were systematically investigated through a series of case studies and global analyses. Substantial differences are found between r (sub e),3.7 and r (sub e),2.1 retrievals (delta r (sub e),3.7-2.l), with a strong dependence on cloud regime. The differences are typically small, within +/- 2 micron, over relatively spatially homogeneous coastal stratocumulus cloud regions. However, for trade wind cumulus regimes, r (sub e),3.7 was found to be substantially smaller than r (sub e),2.1, sometimes by more than 10 micron. The correlation of delta r(sub e),3.7-2.1 with key cloud parameters, including the cloud optical thickness (tau), r (sub e) and a cloud horizontal heterogeneity index (H-sigma) derived from 250 m resolution MODIS 0.86 micron band observations, were investigated using one month of MODIS Terra data. It was found that differences among the three r (sub e) retrievals for optically thin clouds (tau 0.3, both r (sub e),1.6 and r (sub e),2.1 were seen to increase quickly with H-sigma. On the other hand, r (sub e),3.7 statistics showed little dependence on H-sigma and remained relatively stable over the whole range of H-sigma values. Potential contributing causes to the substantial r (sub e),3.7 and r (sub e),2.1 differences are discussed. In particular, based on both 1-D and 3-D radiative transfer simulations, we have elucidated mechanisms by which cloud heterogeneity and 3-D radiative effects can cause large differences between r (sub e),3.7 and r (sub e),2.l retrievals for highly inhomogeneous clouds. Our results suggest that the contrast in observed delta r (sub e)3.7-2.1 between cloud regimes is correlated with increases in both cloud r (sub e) and H-sigma. We also speculate that in some highly inhomogeneous drizzling clouds, vertical structure induced by drizzle and 3-D radiative effects might operate together to cause dramatic differences between r (sub e),3.7 and r (sub e),2.1 retrievals.