cssi/SciSciGPT-SciSciNet huggingface dataset:
Estimates for the extinction time for the Ricci flow on certain 3-manifolds and a question of Perelman

We show that the Ricci flow becomes extinct in finite time on any Riemannian 3-manifold without aspherical summands. In this note we prove some bounds for the extinction time for the Ricci flow on certain 3-manifolds. Our interest in this comes from a question that Grisha Perelman asked the first author at a dinner in New York City on April 25th of 2003. His question was "what happens to the Ricci flow on the 3-sphere when one starts with an arbitrary metric? In particular, does the flow become extinct in finite time?" He then went on to say that one of the difficulties in answering this is that he knew of no good way of constructing minimal surfaces for such a metric in general. However, there is a natural way of constructing such surfaces and that comes from the min-max argument where the minimal of all maximal slices of sweep-outs is a minimal surface; see, for instance, (2). The idea is then to look at how the area of this min-max surface changes under the flow. Geometrically the area measures a kind of width of the 3-manifold and as we will see for certain 3-manifolds (those, like the 3-sphere, whose prime decomposition contains no aspherical factors) the area becomes zero in finite time corresponding to that the solution becomes extinct in finite time. Moreover, we will discuss a possible lower bound for how fast the area becomes zero. Very recently Perelman posted a paper (see (9)) answering his original question about finite extinction time. However, even after the appearance of his paper, then we still think that our slightly different approach may be of interest. In part because it is in some ways geometrically more natural, in part because it also indicates that lower bounds should hold, and in part because it avoids using the curve shortening flow that he simultaneously with the Ricci flow needed to invoke and thus our approach is in some respects technically easier. Let M 3 be a smooth closed orientable 3-manifold and let g(t) be a one-parameter family of metrics on M evolving by the Ricci flow, so
A logic programming framework for combinational circuit synthesis

Logic Programming languages and combinational circuit synthesis tools share a common "combinatorial search over logic formulae" background. This paper attempts to reconnect the two fields with a fresh look at Prolog encodings for the combinatorial objects involved in circuit synthesis. While benefiting from Prolog's fast unification algorithm and built-in backtracking mechanism, efficiency of our search algorithm is ensured by using parallel bitstring operations together with logic variable equality propagation, as a mapping mechanism from primary inputs to the leaves of candidate Leaf-DAGs implementing a combinational circuit specification. After an exhaustive expressiveness comparison of various minimal libraries, a surprising first-runner, Strict Boolean Inequality "<" together with constant function "1" also turns out to have small transistor-count implementations, competitive to NAND-only or NOR-only libraries. As a practical outcome, a more realistic circuit synthesizer is implemented that combines rewriting-based simplification of (<, 1) circuits with exhaustive Leaf-DAG circuit search.
Meeting Biofuels Targets: Implications for Land Use, Greenhouse Gas Emissions, and Nitrogen Use in Illinois

This article develops a dynamic micro-economic land use model to identify the cost-effective allocation of cropland for traditional row crops and perennial grasses and the mix of cellulosic feedstocks needed to meet predetermined biofuel targets over the 2007–2022 period. Yields of perennial grasses obtained from a biophysical model and together with county level data on costs of production for Illinois are used to examine the implications of these targets for crop and biofuel costs, greenhouse gas emissions, and nitrogen use. The economic viability of cellulosic feedstocks is found to depend on their yields per acre and the opportunity cost of land. The mix of viable cellulosic feedstocks varies spatially and temporally with corn stover and miscanthus coexisting in the state; corn stover is viable mainly in central and northern Illinois while miscanthus acres are primarily located in southern Illinois. Biofuel targets lead to a significant shift in acreage from soybeans and pasture to corn and a change in crop rotation and tillage practices. The biofuel targets assumed here lead to a reduction in greenhouse gas emissions, but an increase in nitrogen use.
Two-loop superstrings II. The chiral measure on moduli space

Abstract A detailed derivation from first principles is given for the unambiguous and slice-independent formula for the two-loop superstring chiral measure which was announced in the first paper of this series. Supergeometries are projected onto their superperiod matrices, and the integration over odd supermoduli is performed by integrating over the fibers of this projection. The subtleties associated with this procedure are identified. They require the inclusion of some new finite-dimensional Jacobian superdeterminants, a deformation of the worldsheet correlation functions using the stress tensor, and perhaps paradoxically, another additional gauge choice, “slice μ choice”, whose independence also has to be established. This is done using an important correspondence between superholomorphic notions with respect to a supergeometry and holomorphic notions with respect to its superperiod matrix. Altogether, the subtleties produce precisely the corrective terms which restore the independence of the resulting gauge-fixed formula under infinitesimal changes of gauge-slice. This independence is a key criterion for any gauge-fixed formula and hence is verified in detail.
Generalization error bounds for learning to rank: Does the length of document lists matter?

We consider the generalization ability of algorithms for learning to rank at a query level, a problem also called subset ranking. Existing generalization error bounds necessarily degrade as the size of the document list associated with a query increases. We show that such a degradation is not intrinsic to the problem. For several loss functions, including the cross-entropy loss used in the well known ListNet method, there is no degradation in generalization ability as document lists become longer. We also provide novel generalization error bounds under l1 regularization and faster convergence rates if the loss function is smooth.
On random k-out sub-graphs of large graphs

We consider random sub-graphs of a fixed graph G=(V,E) with large minimum degree. We fix a positive integer k and let Gk be the random sub-graph where each v∈V independently chooses k random neighbors, making kn edges in all. When the minimum degree δ(G)≥(12+ϵ)n,n=|V| then Gk is k-connected w.h.p. for k=O(1); Hamiltonian for ksufficiently large. When δ(G)≥m, then Gk has a cycle of length (1−ϵ)m for k≥kϵ. By w.h.p. we mean that the probability of non-occurrence can be bounded by a function ϕ(n) (or ϕ(m)) where limn→∞ϕ(n)=0.
Mass for the graviton

Can we give the graviton a mass? Does it even make sense to speak of a massive graviton? In this essay I shall answer these questions in the affirmative. I shall outline an alternative to Einstein Gravity that satisfies the Equivalence Principle and automatically passes all classical weakfield tests (GM/r ≈ 10-6). It also passes medium-field tests (GM/r ≈ 1/5), but exhibits radically different strong-field behaviour (GM/r ≈ 1). Black holes in the usual sense do not exist in this theory, and large-scale cosmology is divorced from the distribution of matter. To do all this we have to sacrifice something: the theory exhibits prior geometry, and depends on a non-dynamical background metric.
Is there an alternative to famine relief?: An example from the Sahel☆

Abstract Aid agencies spend large sums on short-term famine relief and are typically unwilling to provide project support for long periods. Yet in at least one case in the Sahel it would be cheaper to provide a long-term subsidy for expert management at an existing irrigation project than to provide periodic famine relief. The project does not fare well using standard cost-benefit techniques but if the opportunity cost of domestic production is measured by the cost of periodic famine relief, continned support is justified.
A CMOS Spiking Neuron for Brain-Inspired Neural Networks With Resistive Synapses and In Situ Learning

Nanoscale resistive memory devices are expected to fuel dense integration of electronic synapses for large-scale neuromorphic systems. To realize such a brain-inspired computing chip, a compact CMOS spiking neuron that performs in situ learning and computing while driving a large number of resistive synapses is desired. This brief presents a novel leaky integrate-and-fire neuron design that implements the dual-mode operation of current integration and synaptic drive, with a single operational amplifier (opamp) and enables in situ learning with crossbar resistive synapses. The proposed design was implemented in a 0.18- $\mu\mbox{m}$ CMOS technology. Measurements show neuron's ability to drive a thousand resistive synapses and demonstrate in situ associative learning. The neuron circuit occupies a small area of 0.01 mm 2 and has an energy efficiency value of 9.3 pJ/spike/synapse.
A benefit of uniform currency

The role of distinct currencies is studied using a random-matching model with randomized trades. The equilibrium concept is the pairwise core in meetings. We show that there exist equilibria in which home and foreign currency play distinct roles and in which the quantities of trade and output are less than the optimal quantities. The benefit of a uniform currency is the elimination of such inferior equilibria. Specifically, any equilibrium in which home and foreign currency play distinct roles is dominated in terms of ex ante welfare by the best one-currency equilibrium -- for some parameters weakly, for some strongly.
De Sitter Space Without Dynamical Quantum Fluctuations

We argue that, under certain plausible assumptions, de Sitter space settles into a quiescent vacuum in which there are no dynamical quantum fluctuations. Such fluctuations require either an evolving microstate, or time-dependent histories of out-of-equilibrium recording devices, which we argue are absent in stationary states. For a massive scalar field in a fixed de Sitter background, the cosmic no-hair theorem implies that the state of the patch approaches the vacuum, where there are no fluctuations. We argue that an analogous conclusion holds whenever a patch of de Sitter is embedded in a larger theory with an infinite-dimensional Hilbert space, including semiclassical quantum gravity with false vacua or complementarity in theories with at least one Minkowski vacuum. This reasoning provides an escape from the Boltzmann brain problem in such theories. It also implies that vacuum states do not uptunnel to higher-energy vacua and that perturbations do not decohere while slow-roll inflation occurs, suggesting that eternal inflation is much less common than often supposed. On the other hand, if a de Sitter patch is a closed system with a finite-dimensional Hilbert space, there will be Poincare recurrences and dynamical Boltzmann fluctuations into lower-entropy states. Our analysis does not alter the conventional understanding of the origin of density fluctuations from primordial inflation, since reheating naturally generates a high-entropy environment and leads to decoherence, nor does it affect the existence of non-dynamical vacuum fluctuations such as those that give rise to the Casimir effect.
Economic and Social Impacts of Self-help Groups in India

This brief summarizes the results of a gender impact evaluation study, entitled Economic and social impacts of self-help groups in India, conducted between 2000 and present in India. The study observed the impact on empowerment and nutritional intake in program areas overall and heterogeneity of impacts between members of pre-existing and newly formed groups, as well as nonparticipants on the individual and household level. There are three main findings. Social capital and economic empowerment increased equally for participants and non-participants in program areas, consistent with the notion that the program generated positive social externalities. Second, there is a significant impact on nutritional status, but the impact was smaller for converted participants than new participants. Finally, there is a significant increase in consumption for participants, but not a gain in income or assets. Funding for the study derived from the Norweigan Environmentally and Socially Sustainable Development (ESSD) Trust Fund, the Gender Action Plan, and the Knowledge for Change Trust Fund.
Couples’ time together: complementarities in production versus complementarities in consumption

Economists have previously suggested that gains from marriage can be generated by complementarities in production (gains from specialization and exchange) or by complementarities in consumption (gains from joint consumption of household public goods and joint time consumption). This paper uses the American Time Use Survey (ATUS) from 2003-2011 to test whether couples that engage in less specialization (are more similar in hours of market work) spend more time together. We find that among married couples without young children, those with a greater difference in weekly hours of work between husband and wife spend less time together on non-working weekend days. Importantly, we find that this relationship is quite symmetric between couples in which the husband works greater hours and couples in which the wife works greater hours. We do not find evidence of a relationship between specialization and couple time together among couples with young children.
Simultaneous lotsizing and scheduling by combining local search with dual reoptimization

Abstract The contribution of this paper is twofold. On the one hand, the particular problem of integrating lotsizing and scheduling of several products on a single, capacitated production line is modelled and solved, taking into account sequence-dependent setup times. Thereby, continuous lotsizes, meeting deterministic dynamic demands, are to be determined and scheduled with the objective of minimizing inventory holding costs and sequence-dependent setup costs. On the other hand, a new general algorithmic approach is presented: A dual reoptimization algorithm is combined with a local search heuristic for solving a mixed integer programming problem. This idea is applied to the above lotsizing and scheduling problem by embedding a dual network flow algorithm into threshold accepting and simulated annealing, respectively. Computational tests show the effectiveness of the new solution method.
SAXS analysis of a linear polyester and a linear polyether urethane—interfacial thickness determination

A small-angle x-ray scattering (SAXS) investigation of two linear segmented polyurethanes was carried out to learn about the respective domain structure (morphology). Both urethanes had a hard segment of methylene-bis(4)phenyl isocyanate (MDI) and butanediol. These two components comprised 28% by weight of each system. The soft segments differed in that one was a polyether (tetramethylene oxide, molecular weight 1000), while the other was a polyester (polytetramethylene adipate, molecular weight 1000). Both of these segmented urethanes were stored at room temperature for over 6 months prior to investigation. Using an automated Kratky camera, SAXS scans were made. By detailed analysis (using the computer program of Vonk) the average interfacial thickness E of the domains was determined by two approaches. The value of E for the polyester was 10–12 A, while it was 5–7 A for the polyether. Within the limits of the assumptions used for analysis, these data directly support the conjecture that polyether urethanes generally lead to better phase separation. Other aspects of the analysis provided further information on the morphological structure. Some cautionary comments are provided on the use of quantitative SAXS data obtained from these or similar systems.
Electronic ground and excited state spectral diffusion of a photocatalyst

Equilibrium and transient 2D IR spectroscopies were used to measure spectral diffusion of the electronic ground and excited states of the photocatalyst Re(bpy)(CO)3Cl. The ground state spectral diffusion decays 3 times faster than the 3MLCT.
Voices from Destruction: Two Eyewitness Testimonies from the Stanisławów Ghetto

This research note explores the influence of prewar cultural experiences on two eyewitnesses’ responses to the Holocaust. While differences of gender, age, and social position affected the emotional responses of the two writers, the historical-cultural prewar context informed their ideological responses. Elisheva Binder, a young woman of twenty-one, was influenced by her literary self-education and her faith in the universality of humanistic ethics. In contrast, the writings of war veteran and Judenrat member Juliusz Feuerman reflect his Zionist convictions. That two such different testimonies demonstrate the strength of prewar ideological influences teaches us that in order to rescue the individuality of the victim from the dehumanizing anonymity of the Holocaust, we must consider the writer’s ideals, values, and ideological background.
Magnetic Stress at the Marginally Stable Orbit: Altered Disk Structure, Radiation, and Black Hole Spin Evolution

Magnetic connections to the plunging region can exert stresses on the inner edge of an accretion disk around a black hole. We recompute the relativistic corrections to the thin-disk dynamics equations when these stresses take the form of a time-steady torque on the inner edge of the disk. The additional dissipation associated with these stresses is concentrated relatively close outside the marginally stable orbit, scaling as r-7/2 at large radius. As a result of these additional stresses, spin-up of the central black hole is retarded; the maximum spin-equilibrium accretion efficiency is 36% and occurs at a/M = 0.94; the disk spectrum is extended toward higher frequencies; line profiles (such as Fe Kα) are broadened if the line emissivity scales with local flux; limb brightening, especially at the higher frequencies, is enhanced; and the returning radiation fraction is substantially increased, up to 58%. This last effect creates possible explanations for both synchronized continuum fluctuations in active galactic nuclei and polarization rises shortward of the Lyman edge in quasars. We show that no matter what additional stresses occur, when a/M < 0.36, the second law of black hole dynamics sets an absolute upper bound on the accretion efficiency.
QUASICLASSICAL APPROACH TO THE WEAK LEVITATION OF EXTENDED STATES IN THE QUANTUM HALL EFFECT

The two-dimensional motion of a charged particle in a random potential and a transverse magnetic field is believed to be delocalized only at discrete energies E{sub N}. In strong fields there is a small positive deviation of E{sub N} from the center of the Nth Landau level, which is referred to as the {open_quotes}weak levitation{close_quotes} of the extended state. I calculate the size of the weak levitation effect for the case of a smooth random potential rederiving earlier results of Haldane and Yang [Phys. Rev. Lett. {bold 78}, 298 (1997)] and extending their approach to lower magnetic fields. I find that as the magnetic field decreases, this effect remains weak down to the lowest field B{sub min} where such a quasiclassical approach is still justified. Moreover, in the immediate vicinity of B{sub min} the weak levitation becomes additionally suppressed. This indicates that the {open_quotes}strong levitation{close_quotes} expected at yet even lower magnetic fields must be of a completely different origin. {copyright} {ital 1998} {ital The American Physical Society}
Thin-Airfoil Theory of an Ejector-Flapped Wing Section

Spence, D. A., "The Lift on a Thin Aerofoil with a Blown Flap," RAE TN Aero 2450, May 1956, Royal Aircraft Establishment, Farnborough, England. Herold, A. C., "A Two-Dimensional, Interative Solution for the Jet Flap," CR-2190, Feb. 1973, NASA. Dvorak, F. A., "Calculation of Turbulent Boundary Layers and Wall Jets over Curved Surfaces," AIAA Journal, Vol. 11, No. 4, April 1973, pp. 517-524. Goradia, S. H. and Colwell, G. T., "Parametric Study of a Two-Dimensional Turbulent Wall Jet in a Moving Stream with Arbitrary Pressure Gradient," AIAA Journal, Vol. 9, No. 11, Nov. 1971, pp. 2156-2165. Kacker, S. C. and Whitelaw, J. H., "Some Properties of the Two-Dimensional Turbulent Wall Jet in a Moving Stream," Journal of Applied Mechanics, Vol. 35, No. 4, Dec. 1968, pp. 641651. Schlichting, H., Boundary Layer Theory, McGraw-Hill, New York, 1968, pp. 590-609. ^Bangert, L. H., "The Turbulent Wall Jet with an Initial Boundary Layer," AIAA Paper 71-612, Palo Alto, Calif., 1971. Gartshore, I. S. and Newman, B. C., "The Turbulent Wall Jet in an Arbitrary Pressure Gradient," The Aeronautical Quarterly, Vol. XX, Pt. I, Feb. 1969, pp. 25-56. Coles, D., Proceedings, Computation of Turbulent Boundary Layers—1968, AFOSP-IFP-Stanford Conference, Vol. II, Aug. 1825, 1968, pp. 1-46. Lawford, J. A. and Foster, D. N., "Low Speed Wind Tunnel Tests on a Wing Section with Plain Leadingand Trailing-Edge Flaps Having Boundary Layer Control by Blowing," RAE TR 69078, April 1969, Royal Aircraft Establishment, Farnborough, England.
Electromagnetic Currents and the Blankenbecler-Sugar Equation

Abstract The effective electromagnetic current density for a two-nucleon system that is described by the Blankenbecler-Sugar equation is derived. In addition to the single nucleon currents there are exchange currents of two different origins. The first is the exchange current that is required to compensate for the violation of the continuity equation in the impulse approximation. The second is an exchange current, which arises in the quasipotential reduction from the Bethe-Salpeter equation and which represents effects of suppressed degrees of freedom. Explicit general expressions are given for both of these exchange currents. The results are applicable to both elastic and inelastic processes.
Pions in the pionless effective field theory

Abstract We show that processes involving pions that remain very near their mass-shell can be reliably computed in the pionless effective field theory, with the pion integrated in as a heavy field. As an application, we compute the π –deuteron scattering amplitude near threshold to next-to-leading order in the momentum expansion. This amplitude is formally dominated by an infrared logarithm of the form log( γ / m π ), where γ is the deuteron binding momentum, and m π is the mass of the pion. The coefficient of this logarithm is determined by the S-wave pion–nucleon scattering lengths.
Realistic models for evolving globular clusters: core collapse with a mass spectrum

Des modeles sont presentes pour l'evolution dynamique des amas globulaires possedant des spectres de masse realistes et generes par une integration numerique directe de l'equation de Fokker-Planck. Le but de l'etude est de calculer les profils de la brillance de surface et des dispersions de vitesse projetee qui peuvent etre compares directement aux observations
HIGH-ENERGY COSMIC-RAY DIFFUSION IN MOLECULAR CLOUDS: A NUMERICAL APPROACH

The propagation of high-energy cosmic rays (CRs) through giant molecular clouds constitutes a fundamental process in astronomy and astrophysics. The diffusion of CRs through these magnetically turbulent environments is often studied through the use of energy-dependent diffusion coefficients, although these are not always well motivated theoretically. Now, however, it is feasible to perform detailed numerical simulations of the diffusion process computationally. While the general problem depends upon both the field structure and particle energy, the analysis may be greatly simplified by dimensionless analysis. That is, for a specified purely turbulent field, the analysis depends almost exclusively on a single parameter—the ratio of the maximum wavelength of the turbulent field cells to the particle gyration radius. For turbulent magnetic fluctuations superimposed over an underlying uniform magnetic field, particle diffusion depends on a second dimensionless parameter that characterizes the ratio of the turbulent to uniform magnetic field energy densities. We consider both of these possibilities and parametrize our results to provide simple quantitative expressions that suitably characterize the diffusion process within molecular cloud environments. Doing so, we find that the simple scaling laws often invoked by the high-energy astrophysics community to model CR diffusion through such regions appear to be fairly robust for the case of a uniform magnetic field with a strong turbulent component, but are only valid up to ~50 TeV particle energies for a purely turbulent field. These results have important consequences for the analysis of CR processes based on TeV emission spectra associated with dense molecular clouds.
PARTIAL TORUS INSTABILITY

Flux ropes are now generally accepted to be the magnetic configuration of coronal mass ejections (CMEs), which may be formed prior to or during solar eruptions. In this study, we model the flux rope as a current-carrying partial torus loop with its two footpoints anchored in the photosphere, and investigate its stability in the context of the torus instability (TI). Previous studies on TI have focused on the configuration of a circular torus and revealed the existence of a critical decay index of the overlying constraining magnetic field. Our study reveals that the critical index is a function of the fractional number of the partial torus, defined by the ratio between the arc length of the partial torus above the photosphere and the circumference of a circular torus of equal radius. We refer to this finding as the partial torus instability (PTI). It is found that a partial torus with a smaller fractional number has a smaller critical index, thus requiring a more gradually decreasing magnetic field to stabilize the flux rope. On the other hand, a partial torus with a larger fractional number has a larger critical index. In the limit of a circular torus when the fractional number approaches 1, the critical index goes to a maximum value. We demonstrate that the PTI helps us to understand the confinement, growth, and eventual eruption of a flux-rope CME.
Harish–Chandra homomorphisms and symplectic reflection algebras for wreath-products

The main result of the paper is a natural construction of the spherical subalgebra in a symplectic reflection algebra associated with a wreath-product in terms of quantum hamiltonian reduction of an algebra of differential operators on a representation space of an extended Dynkin quiver. The existence of such a construction has been conjectured in [EG]. We also present a new approach to reflection functors and shift functors for generalized preprojective algebras and symplectic reflection algebras associated with wreath-products.
Outlier Detection Using Nonconvex Penalized Regression

This article studies the outlier detection problem from the standpoint of penalized regression. In the regression model, we add one mean shift parameter for each of the n data points. We then apply a regularization favoring a sparse vector of mean shift parameters. The usual L1 penalty yields a convex criterion, but fails to deliver a robust estimator. The L1 penalty corresponds to soft thresholding. We introduce a thresholding (denoted by Θ) based iterative procedure for outlier detection (Θ–IPOD). A version based on hard thresholding correctly identifies outliers on some hard test problems. We describe the connection between Θ–IPOD and M-estimators. Our proposed method has one tuning parameter with which to both identify outliers and estimate regression coefficients. A data-dependent choice can be made based on the Bayes information criterion. The tuned Θ–IPOD shows outstanding performance in identifying outliers in various situations compared with other existing approaches. In addition, Θ–IPOD is much ...
Black hole mass of the ultraluminous X-ray source M82 X-1

We report the first clear evidence for the simultaneous presence of a low-frequency break and a QPO in the fluctuation power spectrum of a well-known ultraluminous X-ray source (ULX) in M82 using long XMM-Newton observations. The break occurs at a frequency of 34.2 mHz. The QPO has a centroid at νQPO = 114.3 ± 1.5 mHz, a coherence Q ≡ νQPO/ΔνFWHM 3.5, and an amplitude (rms) of 19% in the 2-10 keV band. The power spectrum is approximately flat below the break frequency and then falls off above the break frequency as a power law with the QPO superposed. This form of the power spectrum is characteristic of the Galactic X-ray binaries (XRBs) in their high or intermediate states. M82 X-1 was likely in an intermediate state during the observation. The EPIC pn spectrum is well described by a model comprising an absorbed power law (Γ ~ 2) and an iron line at ~6.6 keV with a width σ ~ 0.2 keV and an equivalent width of ~180 eV. Using the well-established correlations between the power and energy spectral parameters for XRBs, we estimate a black hole mass for M82 X-1 in the range of ~25-520 M☉, including systematic errors that arise due to the uncertainty in the calibration of the photon spectral index versus QPO frequency relation.
Selective Deposition of Two-Dimensional Colloidal Arrays on Patterned Polyelectrolyte Multilayer Templates

A new method for the patterning of colloidal particles on polymer templates is presented. A polyelectrolyte multilayer film is deposited onto a chemically patterned monolayer surface, which is further used as a functional template to direct the deposition of charged particles through electrostatic and secondary interactions. After modified by an opposite charged surfactant, the particles change their deposition selectivity from the polyelectrolyte surface to a neutral ethylene glycol monolayer surface. Based on the different selectivity, we have first demonstrated a new approach to direct two component colloidal arrays onto a patterned polyelectrolyte multilayer template.
Surface Chemistry of Silicon Nanoclusters

We employ density functional and quantum Monte Carlo calculations to show that significant changes occur in the gap of fully hydrogenated nanoclusters when the surface contains passivants other than hydrogen, in particular atomic oxygen. In the case of oxygen, the gap reduction computed as a function of the nanocluster size provides a consistent interpretation of several recent experiments. Furthermore, we predict that other double bonded groups also significantly affect the optical gap, while single bonded groups have a minimal influence.
Transit-oriented development’s ridership bonus: a product of self-selection and public policies

Transit-oriented development is shown to produce an appreciable ridership bonus in California. This is partly due to residential self-selection—that is, a lifestyle preference for transit-oriented living—as well as factors like employer-based policies that reduce free parking and automobile subsidies. Half-mile catchments of station areas appear to be indifference zones in the sense that residents generally ride transit regardless of local urban design attributes. Out-of-neighborhood attributes, like job accessibility and street connectivity at the destination, on the other hand, have a significant bearing on transit usage among station-area residents. The presence of self-selection, shown using nested logit modeling, underscores the importance of removing barriers to residential mobility so that households are able to sort themselves, via the marketplace, to locations well served by transit. Market-responsive zoning, flexible residential parking policies, location efficient mortgages, and adaptive reuse ...
Cytokeratin antigen in BOP-induced pancreatic tumors—implications for histogenesis

Pancreatic carcinoma induced in the Syrian hamster by the carcinogen N-nitrosobis(2-oxopropyl)amine (BOP) is of interest because of the ductal/ductular morphology of the tumors, which resembles human pancreatic cancer. However, whether hamster tumors arise from pre-existing ductal epithelium or from acinar cells has not yet been determined. The present study shows that a monoclonal antiserum to cytokeratin (an epithelial marker), when applied to normal hamster pancreas sections, stained centroacinar, ductular and ductal epithelium but did not stain acinar cells. We therefore examined pancreatic tissue from hamsters with benign and malignant neoplasms induced by BOP. The antiserum strongly stained the cells of all BOP-induced lesions (cysts, pseudoductules, hyperplasia, dysplasia and carcinomas). No acinar cell staining was observed in BOP-treated pancreas. These findings support the hypothesis that BOP-induced neoplasms arise from ductal epithelium and not from acinar cells.
Comments on 2D type-IIA string and matrix model

We consider a type IIA-like string theory with RR-flux in two dimension and propose its matrix model dual. This string theory describes a Majorana fermion in the two dimensional spacetime. We also discuss its scattering amplitudes both in the world-sheet theory and in the matrix model.
The Evolution of Radio Galaxies and X-Ray Point Sources in Coma Cluster Progenitors since z ~ 1.2

Using Chandra imaging spectroscopy and Very Large Array (VLA) L-band radio maps, we have identified radio sources at P{sub 1.4GHz} {>=} 5 x 10{sup 23} W Hz{sup -1} and X-ray point sources (XPSs) at L{sub 0.3-8 keV} {>=} 5 x 10{sup 42} erg s{sup -1} in L > L* galaxies in 12 high-redshift (0.4 0.4 cluster fields, the increased numbers and luminosities of the CRS radio galaxies and XPSs suggest a substantial (9-10-fold) increase in the heat injected into high-redshift clusters by AGNs compared to the present epoch.« less
Homology of the boolean complex

We construct and analyze an explicit basis for the homology of the boolean complex of a finite simple graph. This provides a combinatorial description of the spheres in the wedge sum representing the homotopy type of the complex. We assign a set of derangements to any finite simple graph. For each derangement, we construct a corresponding element in the homology of the complex, and the collection of these elements forms a basis for the homology of the boolean complex. In this manner, the spheres in the wedge sum describing the homotopy type of the complex can be represented by a set of derangements. We give an explicit, closed-form description of the derangements that can be obtained from any finite simple graph, and compute this set for several families of graphs. In the cases of complete graphs and Ferrers graphs, these calculations give bijective proofs of previously obtained enumerative results.
DECENT: A decentralized architecture for enforcing privacy in online social networks

A multitude of privacy breaches, both accidental and malicious, have prompted users to distrust centralized providers of online social networks (OSNs) and investigate decentralized solutions. We examine the design of a fully decentralized (peer-to-peer) OSN, with a special focus on privacy and security. In particular, we wish to protect the confidentiality, integrity, and availability of user content and the privacy of user relationships. We propose DECENT, an architecture for OSNs that uses a distributed hash table to store user data, and features cryptographic protections for confidentiality and integrity, as well as support for flexible attribute policies and fast revocation. DECENT ensures that neither data nor social relationships are visible to unauthorized users and provides availability through replication and authentication of updates. We evaluate DECENT through simulation and experiments on the PlanetLab network and show that DECENT is able to replicate the main functionality of current centralized OSNs with manageable overhead.
Estimating Housing Demand With an Application to Explaining Racial Segregation in Cities

We present a three-stage, nonparametric estimation procedure to recover willingness to pay for housing attributes. In the first stage we estimate a nonparametric hedonic home price function. In the second stage we recover each consumer's taste parameters for product characteristics using first-order conditions for utility maximization. Finally, in the third stage we estimate the distribution of household tastes as a function of household demographics. As an application of our methods, we compare alternative explanations for why blacks choose to live in center cities while whites suburbanize.
Character and Environment: The Status of Virtues in Organizations

Using evidence from experimental psychology, some social psychologists, moral philosophers and organizational scholars claim that character traits do not exist and, hence, that the philosophical tradition of virtue ethics is empirically inadequate and should dispose of the notion of character to accommodate the empirical evidence. In this paper, I systematically address the debate between dispositionalists and situationists about the existence, status and properties of character traits and their manifestations in human behavior, with the ultimate goal of responding to the question whether virtue ethicists need to abandon the very enterprise of building a character-based moral theory in business ethics and organizational behavior. In the course of this paper, I shall defend the claim that the situationist argument relies on a misinterpretation of the experimental evidence.
Correlated basis theory of nucleon optical potential in nuclear matter

Abstract We give a brief and simple outline of correlated basis perturbation theory and use it to study the optical potential of nucleons in nuclear matter. The correlated basis functions (CBF) are generated with two-body correlation operators having central, spin, isospin, tensor and spin-orbit terms and realistic nuclear interactions are used to construct the hamiltonian matrix. The zeroth-order term in the CBF perturbation expansion is given by the variational method, and there are no first-order contributions. The second-order CBF correction to the binding energy is calculated. The real and imaginary parts U(ρ, e) and W0(ρ, e) of the energy-dependent nucleon optical potential in nuclear matter are calculated at the equilibrium density ρ0 and at ρ = 1 2 ρ 0 . The second-order terms have a relatively small effect on U(ρ, e), but they enhance the nucleon effective mass at k = kF from its variational values of 0.64m and 0.78m to 0.81m and 1.0m at ρ = ρ0 and 1 2 ρ 0 respectively. The calculated U and W0 are in fairly good agreement with empirical data.
Molecular differentiation of neurons from ependyma-derived cells in tissue cultures of regenerating teleost spinal cord

Abstract Cells cultured from the caudalmost area of regenerating teleost spinal cord differ both morphologically and in terms of molecular architecture from those of more rostral (more fully differentiated) areas of the cord. The caudalmost regenerating cord consists of an ependymal tube. Cells from this region have flattened or partially flattened cell somas and short spike projections in vitro; they do not exhibit the rounded cell somas nor the long, thin, branching neurites typical of differentiated neurons. A series of cultures taken from different areas along the length of regenerating spinal cord were examined for molecular differentiation by staining with a monoclonal antibody against non-phosphorylated neurofilament protein (SMI 32). None of the cells from the caudalmost culture of the regenerating spinal cord stained with antibody SMI 32. In cultures of more rostral regenerated cord, the cells with neuronal morphology do stain positively with the anti-neurofilament antibody. This result suggests that the cells in the cultures of caudalmost cord represent relatively undifferentiated ependymal cells, or ependyma-derived cells, which later differentiate into neurons and glia in the regenerating spinal cord.
Sliding Mode Control of the X-33 With an Engine Failure

Ascent flight control of the X-3 is performed using two XRS-2200 linear aerospike engines. in addition to aerosurfaces. The baseline control algorithms are PID with gain scheduling. Flight control using an innovative method. Sliding Mode Control. is presented for nominal and engine failed modes of flight. An easy to implement, robust controller. requiring no reconfiguration or gain scheduling is demonstrated through high fidelity flight simulations. The proposed sliding mode controller utilizes a two-loop structure and provides robust. de-coupled tracking of both orientation angle command profiles and angular rate command profiles in the presence of engine failure, bounded external disturbances (wind gusts) and uncertain matrix of inertia. Sliding mode control causes the angular rate and orientation angle tracking error dynamics to be constrained to linear, de-coupled, homogeneous, and vector valued differential equations with desired eigenvalues. Conditions that restrict engine failures to robustness domain of the sliding mode controller are derived. Overall stability of a two-loop flight control system is assessed. Simulation results show that the designed controller provides robust, accurate, de-coupled tracking of the orientation angle command profiles in the presence of external disturbances and vehicle inertia uncertainties, as well as the single engine failed case. The designed robust controller will significantly reduce the time and cost associated with flying new trajectory profiles or orbits, with new payloads, and with modified vehicles
Graph powers and k-ordered Hamiltonicity

It is known that if G is a connected simple graph, then G^3 is Hamiltonian (in fact, Hamilton-connected). A simple graph is k-ordered Hamiltonian if for any sequence v"1, v"2,...,v"k of k vertices there is a Hamiltonian cycle containing these vertices in the given order. In this paper, we prove that if k>=4, then G^@?^3^k^/^2^@?^-^2 is k-ordered Hamiltonian for every connected graph G on at least k vertices. By considering the case of the path graph P"n, we show that this result is sharp. We also give a lower bound on the power of the cycle C"n that guarantees k-ordered Hamiltonicity.
Menu Costs and the Neutrality of Money

A model of endogenous price adjustment under money growth is presented. Firms follow (s,S) pricing policies, and price revisions are imperfectly synchronized. In the aggregate, price stickiness disappears, and money is neutral. The connection between firm price adjustment and relative price variability in the presence of monetary growth is also investigated. The results contrast with those obtained in models with exogenous fixed timing of price adjustment.
Electron population aging models for wide-angle tails

Abstract Color–color diagrams have been useful in studying the spectral shapes in radio galaxies. At the workshop we presented color–color diagrams for two wide-angle tails, 1231+674 and 1433+553, and found that the standard aging models do not adequately represent the observed data. Although the JP and KP models can explain some of the observed points in the color–color diagram, they do not account for those found near the power-law line. This difficulty may be attributable to several causes. Spectral tomography has been previously used to discern two separate electron populations in these sources. The combination spectra from two such overlying components can easily resemble a range of power-laws. In addition, any non-uniformity in the magnetic field strength can also create a power-law-like spectrum. We will also discuss the effects that angular resolution has on the shape of the spectrum.
Strategic directions of computing at Fermilab

Abstract Fermilab computing has changed a great deal over the years, driven by the demands of the Fermilab experimental community to record and analyze larger and larger datasets, by the desire to take advantage of advances in computing hardware and software, and by the advances coming from the R&D efforts of the Fermilab Computing Division. The strategic directions of Fermilab Computing continue to be driven by the needs of the experimental program. The current fixed-target run will produce over 100 TBytes of raw data and systems must be in place to allow the timely analysis of the data. The collider run II, beginning in 1999, is projected to produce of order 1 PByte of data per year. There will be a major change in methodology and software language as the experiments move away from FORTRAN and into object-oriented languages. Increased use of automation and the reduction of operator-assisted tape mounts will be required to meet the needs of the large experiments and large data sets. Work will continue on higher-rate data acquisition systems for future experiments and projects. R&D projects will be pursued as necessary to provide software, tools, or systems which cannot be purchased or acquired elsewhere. A closer working relation with other high energy laboratories will be pursued to reduce duplication of effort and to allow effective collaboration on many aspects of HEP computing.
When is the core equivalence theorem valid

An answer to the question of the title is provided. It is shown that under some conditions the core equivalence theorem holds true (if and) only if the price space is a vector lattice.
A renewal theory approach to IBD sharing

Abstract A long genomic segment inherited by a pair of individuals from a single, recent common ancestor is said to be identical-by-descent (IBD). Shared IBD segments have numerous applications in genetics, from demographic inference to phasing, imputation, pedigree reconstruction, and disease mapping. Here, we provide a theoretical analysis of IBD sharing under Markovian approximations of the coalescent with recombination. We describe a general framework for the IBD process along the chromosome under the Markovian models (SMC/SMC’), as well as introduce and justify a new model, which we term the renewal approximation , under which lengths of successive segments are independent. Then, considering the infinite-chromosome limit of the IBD process, we recover previous results (for SMC) and derive new results (for SMC’) for the mean number of shared segments longer than a cutoff and the fraction of the chromosome found in such segments. We then use renewal theory to derive an expression (in Laplace space) for the distribution of the number of shared segments and demonstrate implications for demographic inference. We also compute (again, in Laplace space) the distribution of the fraction of the chromosome in shared segments, from which we obtain explicit expressions for the first two moments. Finally, we generalize all results to populations with a variable effective size.
Matrilin-1 is an inhibitor of neovascularization.

In the course of conducting a series of studies whose goal was to discover novel endogenous angiogenesis inhibitors, we have purified matrilin-1 (MATN-1) and have demonstrated, for the first time, that it inhibits neovascularization both in vitro and in vivo. Proteins were extracted from cartilage using a 2 m NaCl, 0.01 m HEPES buffer at 4 °C, followed by concentration of the extract. The concentrate was fractionated by size exclusion chromatography, and fractions were then screened for their ability to inhibit capillary endothelial cell (EC) proliferation in vitro. Fractions containing EC inhibitory activity were pooled and further purified by cation exchange chromatography. The resulting fractions from this step were then screened to isolate the antiangiogenic activity in vitro. This activity was identified by tandem mass spectrometry as being MATN-1. Human MATN-1 was cloned and expressed in Pichia pastoris and purified to homogeneity. Purified recombinant MATN-1, along with purified native protein, was shown to inhibit angiogenesis in vivo using the chick chorioallantoic membrane assay by the inhibition of capillary EC proliferation and migration. Finally, using a MATN-1-deficient mouse, we showed that angiogenesis during fracture healing was significantly higher in MATN-1−/− mice compared with the wild type mice as demonstrated by in vivo imaging and by elevated expression of angiogenesis markers including PECAM1, VEGFR, and VE-cadherin.