cssi/SciSciGPT-SciSciNet huggingface dataset:
Recreation planning for energy conservation

Abstract The lack of local public park and recreation facilities in most cities prompts many people to travel long distances to non-urban recreation areas to experience some activities possible in urban parks. Approximately 30% of all non-commercial automobile mileage is related to recreational use. Some of this use can be reduced by improving the quantity and quality of urban park systems. A 10% reduction of recreational travel could have a significant impact on fuel conservation. This will require a departure from the traditional approach, methods, concepts and standards used for urban recreation planning. Selected policies options and planning concepts are outlined to provide energy-conserving public outdoor opportunities in cities.
An Internal Second-Parameter Problem in the Sculptor Dwarf Spheroidal Galaxy

We present BV photometry of the Sculptor dwarf galaxy to V = 22. These data give evidence for a bimodality in Sculptor's metallicity distribution based on a discontinuity in the luminosities of horizontal-branch (HB) stars and by the presence of two distinct red giant branch (RGB) bumps. A consistent picture of the evolved stars in Sculptor is given by the presence of (1) a metal-poor population of [Fe/H] ~ -2.3 with an exclusively blue HB and that corresponds to the blueward side of the Sculptor RGB and the more luminous RGB bump, and (2) a less metal-poor population of [Fe/H] ~ -1.5 required to explain the less luminous red HB, the red side of the RGB, and a second, less luminous RGB bump. Best fits to the HB populations are obtained with enhanced oxygen abundances, [O/Fe] ~ +0.5. Variations in the global HB and RGB morphology of Sculptor can be explained by differences in the radial distribution of the two different [Fe/H] populations. The presence of these two populations shows that the Sculptor dwarf galaxy has an internal second-parameter problem.
Supergravity instantons and the universal hypermultiplet

The effective action of N = 2 supersymmetric five-dimensional supergravity arising from compactifications of M-theory on Calabi-Yau threefolds receives non-perturbative corrections from wrapped euclidean membranes and fivebranes. These contributions can be interpreted as instanton corrections in the five-dimensional field theory. Focusing on the universal hypermultiplet, a solution of this type is presented and the instanton action is calculated, generalizing previous results involving membrane instantons. The instanton action is not a sum of membrane and fivebrane contributions: it has the form reminiscent of non-threshold bound states.
Rental Housing Markets, the Incidence and Duration of Vacancy, and the Natural Vacancy Rate☆

Abstract New intermetropolitan and time-series data from the BLS are used to derive and model the incidence and duration of rental vacancies and to assess their importance to the price adjustment mechanism for rental housing. Research findings indicate that duration varies with measures of MSA housing costs and housing stock heterogeneity, while incidence varies with measures of population mobility, public housing availability, and population growth. Results support a more general specification of rental price adjustment in which the rate of real rent change reflects deviations in observed vacancy incidence and duration from their equilibrium levels. The research provides new estimates of equilibrium vacancy rates for a large set of metropolitan areas over the 1987–1996 period.
Wavelength dependence of the polarization of the sunlit sky

The blue sky was observed near 90° from the sun, in the vertical plane through the direction of the sun, with the sun above and just below the horizon. The observations were made with six filters ranging from 3250 to 9400 A. For a normal clear sky at the McDonald Observatory with the sun 11.°5 above the horizon, 75% polarization was found at 5500 A. The agreement of the Rayleigh–Chandrasekhar theory with the observations is good. The difference of the above 75% with 100% polarization appears to be due to multiple scattering (6%), molecular anisotropy (6%), and reflection by the ground (5%), while a residual 8% is presumably due to aerosols. At the McDonald Observatory, the polarization of the daytime sky has a maximum near 5500 A, with a decrease toward longer as well as toward shorter wavelengths. The decline in the ultraviolet is caused by multiple scattering, while in the infrared it is mostly due to ground reflection, which is especially strong when green plants are present.
Quantum stochastic resonance in the strong-field limit

Numerical path integral calculations are performed to study the behavior of a dissipative two-level system driven by a strong monochromatic oscillatory field. It is shown that the population of an initially localized state displays persistent high-frequency oscillations at weak dissipation and low temperature. The oscillation amplitudes exhibit intricate patterns as the field parameters are varied. The observed behavior is an extension of the quantum stochastic resonance phenomenon outside the weak-field regime.
A Catalyst that Plays Multiple Roles: Asymmetric Synthesis of β-Substituted Aspartic Acid Derivatives through a Four-Stage, One-Pot Procedure

We report a new method for the catalytic, asymmetric synthesis of β-substituted aspartic acid derivatives in which the nucleophilic catalyst serves up to four discrete roles in a one-pot procedure: catalytic dehydrohalogenation of acid chlorides to form ketenes; catalytic dehydrohalogenation of α-chloroamines to form the corresponding imines; catalyzed [2 + 2]-cycloaddition to produce intermediate acyl β-lactams; and finally, nucleophilic ring opening to afford optically enriched β-substituted aspartic acids in high enantioselectivity and diastereoselectivity.
Magnetic-field-induced Luttinger liquid

It is shown that a strong magnetic field applied to a bulk metal induces a Luttinger-liquid phase. This phase is characterized by the zero-bias anomaly in tunneling: the tunneling conductance scales as a power law of voltage or temperature. The tunneling exponent increases with the magnetic field as Bln B. The zero-bias anomaly is most pronounced for tunneling with the field applied perpendicular to the plane of the tunneling junction.
Stability Analysis of Lattice Boltzmann Methods

The lattice Boltzmann equation describes the evolution of the velocity distribution function on a lattice in a manner that macroscopic fluid dynamical behavior is recovered. Although the equation is a derivative of lattice gas automata, it may be interpreted as a Lagrangian finite-difference method for the numerical simulation of the discrete-velocity Boltzmann equation that makes use of a BGK collision operator. As a result, it is not surprising that numerical instability of lattice Boltzmann methods have been frequently encountered by researchers. We present an analysis of the stability of perturbations of the particle populations linearized about equilibrium values corresponding to a constant-density uniform mean flow. The linear stability depends on the following parameters: the distribution of the mass at a site between the different discrete speeds, the BGK relaxation time, the mean velocity, and the wavenumber of the perturbations. This parameter space is too large to compute the complete stability characteristics. We report some stability results for a subset of the parameter space for a 7-velocity hexagonal lattice, a 9-velocity square lattice, and a 15-velocity cubic lattice. Results common to all three lattices are (1) the BGK relaxation time ? must be greater than 12 corresponding to positive shear viscosity, (2) there exists a maximum stable mean velocity for fixed values of the other parameters, and (3) as ? is increased from 12 the maximum stable velocity increases monotonically until some fixed velocity is reached which does not change for larger ?.
Gaussian effective potential for the U(1) Higgs model

In order to investigate the Higgs mechanism nonperturbatively, we compute the Gaussian effective potential of the U(1) Higgs model (“scalar electrodynamics”). We show that the same simple result is obtained in three different formalisms. A general covariant gauge is used, with Landau gauge proving to be optimal. The renormalization generalizes the “autonomous” renormalization for λϕ4 theory and requires a particular relationship between the bare gauge coupling eB and the bare scalar self-coupling λB. When both couplings are small, then λ is proportional to e4 and the scalar/vector mass-squared ratio is of order e2, as in the classic 1-loop analysis of Coleman and Weinberg. However, as λ increases, e reaches a maximum value and then decreases, and in this “nonperturbative” regime the Higgs scalar can be much heavier than the vector boson. We compare our results to the autonomously renormalized 1-loop effective potential, finding close agreement in the physical predictions. The main phenomenological implication is a Higgs mass of about 2 TeV.
A Composite HST Spectrum of Quasars

We construct a composite quasar spectrum from 284 HST FOS spectra of 101 quasars with redshifts z > 0.33. The spectrum covers the wavelengths between 350 and 3000 A in the rest frame, with a peak S/N level of ~130 per A at ~1200 A. Since ~90% of the sample quasars have redshift z 1.5 quasars, for which significant corrections for the accumulated Lyman-series line and continuum absorption have been applied. There is a significant steepening of the continuum slope around 1050 A. The continuum between 1050 and 2200 A can be modeled as a power law fν να with α = -0.99 ± 0.05. For the full sample the power-law index in the extreme ultraviolet (EUV) between 350 and 1050 A is α = -1.96 ± 0.15. For the radio-loud subsample (60 objects), the EUV spectral index is α -2.2, while for the radio-quiet subsample (41 objects) it is α -1.8. The continuum flux in the wavelengths near the Lyman limit shows a depression of ~10%. The break in the power-law index and the slight depression of the continuum near the Lyman limit are features expected in Comptonized accretion-disk spectra. Comptonization produces a power-law tail in the wavelength band shortward of ~1000 A and smears out the Lyman-limit edge of the intrinsic accretion-disk spectrum. In the EUV waveband, we detect several possible emission features, including one around 690 A that may be O III + N III produced by the Bowen fluorescence effect. Comparing our composite spectrum with one made at higher redshifts by Francis et al., we find that the equivalent widths of Lyα and high-ionization emission lines are larger in our sample, reflecting a known luminosity dependence. The equivalent widths of low-ionization lines do not exhibit such a dependence, suggesting that the quasar EUV continuum above ~50 eV is steeper at higher luminosity. Radio-quiet quasars appear to show a slightly harder continuum and lower ionization levels in their emission lines.
Mechanism for a next-to-lowest lying scalar meson nonet

Recent work suggests the existence of a nonconventional lowest-lying scalar nonet containing the a{sub 0}(980). Then the a{sub 0}(1450) and also the K{sub 0}{sup *}(1430) are likely candidates to belong to a conventional p-wave qq(bar sign) nonet. However, a comparison of their properties with those expected on this basis reveals a number of puzzling features. It is pointed out that these puzzles can be resolved in a natural and robust way by assuming a ''bare'' conventional p-wave scalar qq(bar sign) nonet to mix with a lighter four-quark qqq(bar sign)q(bar sign) scalar nonet to form new ''physical'' states. The essential mechanism is driven by the fact that the isospinor is lighter than the isovector in the unmixed qqq(bar sign)q(bar sign) multiplet. (c) 2000 The American Physical Society.
X-Ray Spectroscopy of II Pegasi: Coronal Temperature Structure, Abundances, and Variability

We have obtained high-resolution X-ray spectra of the coronally active binary II Pegasi (HD 224085), covering the wavelength range of 1.5-25 A. For the first half of our 44 ks observation, the source was in a quiescent state with constant X-ray flux, after which it flared, reaching twice the quiescent flux in 12 ks, then decreased. We analyze the emission-line spectrum and continuum during quiescent and flaring states. The differential emission measure derived from lines fluxes shows a hot corona with a continuous distribution in temperature. During the nonflare state, the distribution peaks near log T = 7.2, and when flaring, it peaks near 7.6. High-temperature lines are enhanced slightly during the flare, but most of the change occurs in the continuum. Coronal abundance anomalies are apparent, with iron very deficient relative to oxygen and significantly weaker than expected from photospheric measurements, while neon is enhanced relative to oxygen. We find no evidence of appreciable resonant scattering optical depth in line ratios of iron and oxygen. The flare light curve is consistent with solar two-ribbon flare models but with a very long reconnection time constant of about 65 ks. We infer loop lengths of about 0.05 to about 0.25 stellar radii in the flare, if the flare emission originated from a single, low-density loop.
Response of a cylindrical shell to random acoustic excitation

Response and equivalent force spectra have been investigated for random acoustic excitation of a cylindrical shell within a narrow frequency band of relatively low-modal density. Theoretical and experimental results are compared for single-point transfer functions, acoustic mobility functions, response and equivalent force power spectral densities, and coherence functions. In general, it is found that a purely theoretical prediction of response based on linear random process theory is severely limited because of the inability of currently available expressions for transfer functions to account for various deviations which result principally from imperfections and eccentricities in the cylinder. However, good agreement is achieved between measured response and that calculated with measured transfer functions. It is further indicated that a rather coarse discrete representation of a continuously distributed excitation is possible.
Photoluminescence of the Incompressible Laughlin Liquid: Excitons, Charged Excitons, and Fractionally Charged Excitons

The photoluminescence (PL) of a two-dimensional electron gas (2DEG) in a high magnetic field is studied as a function of the filling factor and the separation d between the electron layer and the valence hole. Depending on the magnitude of d relative to the magnetic length λ, two distinct regimes in the response of the 2DEG to the valence hole occur, with different elementary emission processes contributing to the PL spectrum. At d λ (weak coupling regime), the hole decouples or binds one or two Laughlin quasi-electrons to form fractionally charged excitons (FCXs). The binding energies as well as the emission energies and intensities of all X and FCX states are calculated.
Sequential bidding in auctions of construction contracts

We analyze bidding patterns in morning and afternoon auctions of construction contracts. We find no statistically significant difference in the probability to bid in the afternoon between those who won and those who lost in morning sessions. As a result, the information released in the morning increases the observable asymmetries and affects bidding behavior. Firms that win in the morning bid more aggressively, in the absolute sense, in the afternoon. However, those who lost in morning sessions bid more aggressively, relative to their morning bids, than those who won in the morning.
Rate-constrained block-matching algorithm

The rate constrained block matching algorithm (RC-BMA), introduced in this paper jointly minimizes DFD variance and entropy or conditional entropy of motion vectors for determining the motion vectors in low rate video coding applications where the contribution of the motion vector rate to the overall coding rate might be significant. The motion vector rate versus DFD variance performance of RC-BMA employing size KxK blocks is shown to be superior to that of the conventional minimum distortion block matching algorithm (MD-BMA) employing size 2Kx2K blocks. Constraining of the entropy or conditional entropy of motion vectors in RC-BMA results in smoother and more organized motion vector fields with respect to those output by MD-BMA. The motion vector rate of RC-BMA can also be fine tuned to a desired level for each frame by adjusting a single parameter.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
The Seyfert-Starburst Connection in X-Rays. I. The Data

We analyze X-ray spectra and images of a sample of Seyfert 2 galaxies that unambiguously contain starbursts, based on their optical and UV characteristics. Although all sample members contain active galactic nuclei (AGNs), supermassive black holes or other related processes at the galactic centers alone cannot account for the total X-ray emission in all instances. Eleven of the 12 observed galaxies are significantly resolved with the ROSAT High Resolution Imager, while six of the eight sources observed with the lower resolution Position Sensitive Proportional Counter also appear extended on larger scales. The X-ray emission is extended on physical scales of 10 kpc and greater, which we attribute to starburst-driven outflows and supernova heating of the interstellar medium. Spectrally, a physically motivated composite model of the X-ray emission that includes a heavily absorbed (NH > 1023 cm-2) nuclear component (the AGN), power-law-like scattered AGN flux, and a thermal starburst describes this sample well. Half the sample exhibit iron Kα lines, which are typical of AGNs.
On Approximation Algorithms for Hierarchical MAX-SAT

We prove upper and lower bounds on performance guarantees of approximation algorithms for the hierarchical MAX-SAT (H-MAX-SAT) problem. This problem is representative of a broad class of PSPACE-hard problems involving graphs, Boolean formulas, and other structures that are defined succinctly.Our first result is that, for some constant ?<1, it is PSPACE-hard to approximate the function H-MAX-SAT to within ratio ?. We obtain our result using a reduction from the language recognition problem for a model of PSPACE called the probabilistically checkable debate system. As an immediate application, we obtain nonapproximability results for functions on hierarchical graphs by combining our result with previously known approximation-preserving reductions to other problems. For example, it is PSPACE-hard to approximate H-MAX-CUT and H-MAX-INDEPENDENT-SET to within some constant factor.Our second result is that there is an efficient approximation algorithm for H-MAX-SAT with performance guarantee 2/3. The previous best bound claimed for this problem was 1/2. One new technique of our algorithm can be used to obtain approximation algorithms for other problems, such as hierarchical MAX-CUT, which are simpler than previously known algorithms and which have performance guarantees that match the previous best bounds.
Compression aware physical database design

Modern RDBMSs support the ability to compress data using methods such as null suppression and dictionary encoding. Data compression offers the promise of significantly reducing storage requirements and improving I/O performance for decision support queries. However, compression can also slow down update and query performance due to the CPU costs of compression and decompression. In this paper, we study how data compression affects choice of appropriate physical database design, such as indexes, for a given workload. We observe that approaches that decouple the decision of whether or not to choose an index from whether or not to compress the index can result in poor solutions. Thus, we focus on the novel problem of integrating compression into physical database design in a scalable manner. We have implemented our techniques by modifying Microsoft SQL Server and the Database Engine Tuning Advisor (DTA) physical design tool. Our techniques are general and are potentially applicable to DBMSs that support other compression methods. Our experimental results on real world as well as TPC-H benchmark workloads demonstrate the effectiveness of our techniques.
Bisindolines from the reaction of 3,5-dimethoxyaniline with vicinal diones

Substituted bisindolines were synthesized from the reaction of 3,5-dimethoxyaniline and vicinal diones (2,3-butanedione, benzil, and 4-methylbenzil). The reaction of 3,5-dimethoxyaniline with 2,3-butanedione under polar acidic conditions proceeded with an unanticipated double cyclization reaction forming 2,2′-dimethyl-5,5′,7,7′-tetramethoxybisindole, (+/−)-1. The reaction of 3,5-dimethoxyaniline with benzil under similar conditions did not form a bisindoline, but instead formed cis-1,2-diphenyl-2-[(3,5-dimethoxyphenyl)imino]ethanone, 2. When the solvent, acid, and reaction temperature were changed for the reaction of 3,5-dimethoxyaniline with benzil, 3,3-diphenyl-4,6-dimethoxyindolin-2-one, 3 (an isomer of 2), and 2,2′-diphenyl-5,5′,7,7′-tetramethoxybisindole, (+/−)-4, were isolated as major and minor products, respectively. Similarly, the reaction of 3,5-dimethoxyaniline with 4-methylbenzil produced a 1 : 1 mixture of cis-1-(4-methylphenyl)-2-phenyl-2-[(3,5-dimethoxyphenyl)-imino]ethanone, 6a, and cis-1-(phenyl)-2-(4-methylphenyl)-2-[(3,5-dimethoxyphenyl)imino]ethanone, 6b, under polar acidic conditions and 3-(4-methylphenyl)-3-phenyl-4,6-dimethoxyindolin-2-one, (+/−)-7 and 2-(4-methylphenyl)-2′-phenyl-5,5′,7,7′-tetramethoxybisindole, (+/−)-8, under apolar acidic conditions at elevated temperature. We propose the mechanism of bisindoline and indolinone formation to include a Friedel–Crafts type electrophilic attack on the electron rich aryl ring at the ring closing C–C bond forming steps, and further propose a common carbocationic monocyclized intermediate.
A Frequency Glitch in an Accreting Pulsar

Frequency glitches have been observed so far only in radio pulsars and anomalous X-ray pulsars. Here we present evidence of a glitch in a neutron star accreting from a Be companion. The transient KS 1947+300 reappeared in 2000 October as a moderately strong X-ray source that exhibited 18.7 s pulsations, leading to an identification with the BATSE source GRO J1948+32, last detected in 1994. We have analyzed Rossi X-Ray Timing Explorer (RXTE) observations taken during the 2000-2001 outburst, as well as additional observations taken during a smaller outburst in 2002 July. Orbital Doppler shifts are apparent in the temporal variation of the pulse frequency. A joint fit of the RXTE data together with BATSE measurements from an outburst in 1994 yields the orbital period Porb = 40.415 ± 0.010 days, the projected orbital radius aX sin i = 137 ± 3 lt-s, and the eccentricity e = 0.033 ± 0.013. This degree of eccentricity is unexpectedly low for such a wide orbit. Pulse timing results also show that the intrinsic pulse frequency increased from 53.30 to 53.47 mHz at a rate approximately proportional to the X-ray flux. This is about the degree of spin-up expected from the accretion torques that must be present when the X-ray luminosity reaches ~1038 ergs s-1. On one occasion during the 2000-2001 outburst, the pulse frequency increased by ~1.8 × 10-6 Hz in 10 hr over and above the mean trend seen around that time, without any indication of a correspondingly large increase in X-ray flux. The fractional change in frequency of 3.7 × 10-5 during this event is significantly larger than the values observed in the glitches in radio pulsars and anomalous X-ray pulsars. We discuss other similarities and differences between these events.
A Tandem Carbanion Addition/Carbon−Carbon Bond Cleavage Yields Alkynyl Ketones

Carbanion addition to vinylogous acid triflates triggers carbon−carbon bond cleavage to form alkynyl ketones under mild conditions. Mechanistic factors affecting the cleavage event and its relationship to complementary fragmentations are discussed. A range of tethered keto−alkynes are obtained by a unified approach.
Refining the elliptic genus

Abstract We show how special forms an N = 2 Landau-Ginzburg potential directly imply the presence of an N = 2 super- W algebra. If the Landau-Ginzburg model has a super- W algebra, we show how the elliptic genus can be refined so as to give much more complete information about the structure of the model. We study the super- W 3 model in some detail, and present some results and conjectures about more general models.
Teleoperation, Telerobotics, and Telepresence: A Progress Report

Abstract This paper briefly surveys and reports progress in the field of teleoperation, meaning human control of remote sensors and actuators. Included is the subclass of teleoperation called telerobotics, which means human supervisory control of remote semiautomatic systems, and the phenomenon of telepresence, in which special sensing and display technology enables the human to feel present at the remote location even though not really there. Current and new applications are reviewed. Techniques for human-computer cooperation in planning, commanding, and sensing are described. The telerobot is considered as a paradigm for any complex vehicle or process having many separate automatic control loops all of which are supervised by a human; some current examples are presented. Finally, opinions are given as to the current status of the field.
Implicit Monte Carlo diffusion---an acceleration method for Monte Carlo time-dependent radiative transfer simulations

Abstract Implicit Monte Carlo (IMC) is often employed to numerically simulate radiative transfer. In problems with regions that are characterized by a small mean free path, IMC can take a prohibitive amount of time, because many particle steps must be simulated to advance the particle through the time step. Problems containing regions with a small mean free path can frequently be accurately simulated much more quickly by employing the diffusion equation as an approximation. However, the diffusion approximation is not accurate in regions of the problem where the mean free path is large. We present a method for accelerating time-dependent Monte Carlo radiative transfer calculations by using a discretization of the diffusion equation to calculate probabilities that are used to advance particles in regions with small mean free paths. The method is demonstrated on problems with one-and two-dimensional orthogonal grids. It results in decreases in run time of more than an order of magnitude on these problems, while producing answers with accuracy comparable to pure IMC simulations. We call the method Implicit Monte Carlo Diffusion, which we abbreviate IMD.
Iron(III) p-toluenesulfonate catalyzed synthesis of homoallyl ethers from acetals and aldehydes

Abstract Iron(III) p -toluenesulfonate, Fe(OTs) 3 ·6H 2 O, is an inexpensive, versatile and commercially available catalyst for the allylation of acetals using allyltrimethylsilane to yield homoallyl ethers in moderate to good yields. The one-pot conversion of aldehydes to homoallyl ethers using alkoxysilanes has also been accomplished using Fe(OTs) 3 ·6H 2 O as a catalyst. The use of mild reaction conditions and a relatively non-corrosive catalyst make this method an attractive option for the synthesis of a range of homoallyl ethers.
Formation of Galactic Nuclei

We investigate a model in which galactic nuclei form via the coalescence of preexisting stellar systems containing supermassive black holes. Merger simulations are carried out using N-body algorithms that can follow the formation and decay of a black hole binary and its effect on the surrounding stars down to subparsec scales. Our initial stellar systems have steep central density cusps similar to those in low-luminosity elliptical galaxies. Immediately following the merger, the density profile of the remnant is homologous with the initial density profile and the steep nuclear cusp is preserved. However, the formation of a black hole binary transfers energy to the stars and lowers the central density; continued decay of the binary creates a ρ ~ r-1 density cusp similar to those observed in bright elliptical galaxies, with a break radius that extends well beyond the sphere of gravitational influence of the black holes. Our simulations are the first to successfully produce shallow power-law cusps from mergers of galaxies with steep cusps, and our results support a picture in which the observed dependence of nuclear cusp slope on galaxy luminosity is a consequence of galaxy interactions. We follow the decay of the black hole binary over a factor of ~20 in separation after formation of a hard binary, considerably farther than in previous simulations. We see almost no dependence of the binary's decay rate on number of particles in the simulation, contrary to earlier studies in which a lower initial density of stars led to a more rapid depletion of the binary's loss cone. We nevertheless argue that the decay of a black hole binary in a real galaxy would be expected to stall at separations of 0.01-1 pc unless some additional mechanism is able to extract energy from the binary. We discuss the implications of our results for the survivability of dark matter cusps.
Gravitation Physics at BGPL

Abstract We report progress on a program of gravitational physics experiments using cryogenic torsion pendula undergoing large-amplitude torsion oscillation. This program includes tests of the gravitational inverse square law and of the weak equivalence principle. Here, we describe our ongoing search for inverse-square-law violation at a strength down to 10−5 of standard gravity. The low-vibration environment provided by the Battelle Gravitation Physics Laboratory (BGPL) is uniquely suited to this study.
Low‐frequency electromagnetic exploration for groundwater on Mars

Water with even a small amount of dissolved solids has an electrical conductivity orders of magnitude higher than dry rock and is therefore a near-ideal exploration target on Mars for low frequency, diffusive electromagnetic methods. Models of the temperature- and frequency-dependent electrical properties of rock-ice-water mixtures are used to predict the electromagnetic response of the Martian subsurface. Detection of ice is difficult unless it is massively segregated. In contrast, liquid water profoundly affects soundings, and even a small amount of adsorbed water in the cryosphere can be detected. Subcryospheric water is readily distinguishable at frequencies as low as 100 Hz for fresh water to 10 mHz for brines. These responses can be measured using either natural or artificial sources. Ultra low frequency signals from solar wind and diurnal-heating perturbations of the ionosphere are likely, and disturbances of regional crustal magnetic fields may also be observable. Spherics, or extremely to very low frequency signals from lightning discharge, would provide optimal soundings; however, lightning may be the least likely of the possible natural sources. Among the active techniques, only the time-domain electromagnetic (TDEM) method can accommodate a closely spaced transmitter and receiver and sound to depths of hundreds of meters or more. A ground- or aircraft-based TDEM system of several kilograms can detect water to a depth of several hundred meters, and a system of tens of kilograms featuring a large, fixed, rover- or ballistically deployed loop can detect water to several kilometers depth.
New constraints on the thermal and volatile evolution of Mars

Abstract The thermal and volatile evolution of Mars has not been studied from the perspective of consistency with the preservation of the Martian global dichotomy and with estimates of the elastic thickness over time. We use three thermal evolution models for Mars: (1) stagnant lid, (2) early plate tectonics followed by stagnant lid, and (3) mantle overturn, to calculate the amount of relaxation of the dichotomy boundary and elastic thickness values for Noachian- and Hesperian-aged terrains. To explore a wide range of parameters, we evaluate two different initial mantle temperatures, and wet and dry rheologies. Our model results show that the relative water content of the crust has an effect roughly equal to 500 K variations of initial mantle temperature. For all three thermal models, a lower crust viscosity of 10 20 –10 21 Pa s during the first 0.1 Ga after formation of dichotomy would allow for the preservation of the long-wavelength topography of Mars and fitting of the elastic thickness. This viscosity range implies either wet, cold (∼1500 K) lower crust, or dry, hot (∼2000 K) lower crust in Noachian. Additional constraints are necessary to distinguish between the individual thermal models. For the stagnant lid model, neither the cold, wet crust nor the hot, dry crust agree with timing and amount of the crustal production [Hauck II., S.A., Phillips, R.J., 2002. Thermal and crustal evolution of Mars. J. Geophys. Res. 107, 5052]. Moreover, drying of the crust is required for this model in order to match the admittance elastic thickness at the Hesperian/Amazonian boundary implying remelting of the crust. The hot, dry crust in the early plate tectonics model limits a plate tectonic epoch to only 100–200 Myr and implies dry mantle, which is in disagreement with water found in meteorites. The cold, wet crustal rheology implies the formation of crust during the plate tectonics regime because of the low crustal production during the stagnant lid regime. For mantle overturn, the temperature required for wet crust does not fit the original mantle profile while the dry crust does; however, in order to explain the initially hot thermal profile the crust must have been emplaced very fast. Generally, dry crustal rheology does not fit low elastic values in the Hesperian and implies either that rheology may differ between the southern and northern hemispheres: wet in northern hemisphere and dry in southern hemisphere, or that local weakening occurred. Wet crustal rheology fits well all elastic data except S. Hellas rim, which may be anomalous. Mantle rheology is unconstrained by our modeling and can be either dry or wet.
Ideals in triangulated categories: phantoms, ghosts and skeleta

We begin by showing that in a triangulated category, specifying a projective class is equivalent to specifying an ideal I of morphisms with certain properties and that if I has these properties, then so does each of its powers. We show how a projective class leads to an Adams spectral sequence and give some results on the convergence and collapsing of this spectral sequence. We use this to study various ideals. In the stable homotopy category we examine phantom maps, skeletal phantom maps, superphantom maps, and ghosts. (A ghost is a map which induces the zero map of homotopy groups.) We show that ghosts lead to a stable analogue of the Lusternik–Schnirelmann category of a space, and we calculate this stable analogue for low-dimensional real projective spaces. We also give a relation between ghosts and the Hopf and Kervaire invariant problems. In the case ofA∞modules over anA∞ring spectrum, the ghost spectral sequence is a universal coefficient spectral sequence. From the phantom projective class we derive a generalized Milnor sequence for filtered diagrams of finite spectra, and from this it follows that the group of phantom maps fromXtoYcan always be described as alim←1group. The last two sections focus on algebraic examples. In the derived category of an abelian category we study the ideal of maps inducing the zero map of homology groups and find a natural setting for a result of Kelly on the vanishing of composites of such maps. We also explain how pure exact sequences relate to phantom maps in the derived category of a ring and give an example showing that phantoms can compose non-trivially.
Averaged shifted histogram

The averaged shifted histogram or ASH is a nonparametric probability density estimator derived from a collection of histograms. The ASH enjoys several advantages compared with a single histogram: better visual interpretation, better approximation, and nearly the same computational efficiency. The ASH provides a bridge between the histogram and advanced kernel methods; moreover, the ASH provides a method of choice for kernel implementation. Copyright © 2009 John Wiley & Sons, Inc. For further resources related to this article, please visit the WIREs website.
Shallow casing shoe integrity interpretation technique

Abstract Unlike the leak-off testing (LOT) in deep wells, the LOT plots from shallow well sections subsea are often inconclusive due to the lack of an obvious point of deflection from their initial linear behavior. In the paper, simultaneous effects of geo-mechanical factors and fall-off mechanism have been combined to explain and analyze the tests in shallow marine sediments (SMS). Based on theoretical analysis, three main stages of leak-off plot from SMS, pressure buildup, stabilization and fall-off are identified and explained. Non-linearity of the pressure buildup and mechanisms controlling pressure stabilization are explained and used to develop a method to analyze LOT. The presented interpretation procedure considers separately the pressure stabilization and the pressure buildup and fall-off sections of the LOT plot. The procedure combines well data with pressure testing record. Well data includes overburden pressure — calculated from correlations specific for SMS, and the maximum cementing pressure at the time of slurry placement. The stabilized LOT pressure analysis identifies the maximum strength of the casing shoe controlled by the rock stress (overburden pressure) and the failure by rock fracturing. Also presented is a graphical procedure for comparing the plots of actual and equivalent pressure fall-off. The graphical procedure provides a pattern-recognition method to distinguish the mechanism of cement–rock parting from the fluid loss mechanism.
Intensity distribution in the rotation-vibration spectrum of the OH molecule

The rotation-vibration spectrum of OH has been observed byMeinel in the light of the night sky. For the purpose of establishing the mechanism leading to this emission calculations have been made of the intensity distribution in the vibration spectrum of a Morse oscillator equivalent to the OH molecule. On the assumption of a linear dipole moment variation an explicit formula for the transition probabilities is obtained and the numerical values are evaluated up toν=12. If the assumption is made that the OH molecules in the night sky are first formed in theν=9 level and then cascade down toν=0 an intensity distribution similar to the observed is found. The effect of a quadratic term in the dipole moment is also considered. The matrix elements of this quadratic term are evaluated up toν′=8 andν″= 3. By introducing these quadratic terms into the transition probabilities a fair quantitative agreement is obtained between observed and calculated relative intensities. Predictions are made for the intensities of the OH bands of theΔ ν= 1, 2, and 3 sequences which lie in the farther infrared not yet investigated in the night sky. A rough estimate of the number of OH molecules formed in the upper atmosphere in theν= 9 level per second and per cm2 column is 9×1011.
Mitigation of malware proliferation in P2P networks using Double-layer Dynamic Trust (DDT) management scheme

Peer-to-peer (P2P) networking is used by users with similar interests to exchange, contribute, or obtain files. This network model has been proven popular to exchange music, pictures, or software applications that are saved, and most likely executed at the downloading host. At the expense of this mechanism, worms, viruses, and intruding files find an open front door to the downloading host and giving them place to a very convenient environment for successful proliferation throughout the network. Although virus detection software are currently available, this countermeasure works in a reactive approach and most times isolated manner. In this paper, we consider a trust management scheme to contain the proliferation of viruses in P2P networks. Specifically, we propose a trust management system based on a two-layer approach to bound the proliferation of viruses. The new scheme is called Double-layer Dynamic Trust (DDT) management scheme. Our results show the proposed scheme bounds virus proliferation. With this approach, the number of infected hosts and proliferation rate are limited to small values. We compare our results to other existing approaches.
How JWST can measure first light, reionization and galaxy assembly

We summarize the design and performance of the James Webb Space Telescope that is to be launched to an L2 orbit in 2013, and how it is designed, in particular, to study the epochs of first light, reionization and galaxy assembly.
Estimation of a dynamic model of weight

The ongoing debate about the economic causes of obesity has focused on the changing relative prices of diet and exercise. This paper uses a model that explicitly includes time and spatially varying community-level urbanicity and price measures as instruments to obtain estimates of the effects of diet, physical activity, drinking, and smoking on weight. The instruments control for bias due to unobservables that may be common determinants of weight and these explanatory variables. We apply a dynamic panel system GMM estimation model to longitudinal (1991–2006) data from China to model weight and find that among adult men in China, about 5.4% of weight gain was due to declines in physical activity and 2.8–3.1% was due to dietary changes over this period. Combined, changes in physical activity and diet only explain around 8% of the short run gain in weight and about 11% of the long-run gain in weight among Chinese men.
Synthesis and Size Control of Luminescent II-VI Semiconductor Nanocrystals by a Novel Microemulsion-Gas Contacting Technique

A scalable, room-temperature technique for controlled synthesis of luminescent II-VI nanocrystals has been developed by using the dispersed phase of stable, well-characterized microemulsions as templates for nanoparticle synthesis. The microemulsions were formed by self-assembly of poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) (PEO-PPO-PEO) amphiphilic block copolymer and heptane in formamide. By adjusting the surfactant to dispersed phase ratio, stable microemulsions were obtained with droplet diameter of ∼40nm. These microemulsions avoid problems or rapid droplet-droplet coalescence that hamper reverse micelles and lead to polydisperse particle populations. Luminescent ZnSe quantum dots were synthesized by reacting diethylzinc (dissolved in the heptane dispersed phase) with hydrogen selenide gas (diluted in hydrogen). The gas was bubbled through the microemulsion, dissolved in the formamide, and diffused to the nanodroplet interfaces to react with diethylzinc. The experiments indicate that a single nanocrystal is formed in each nanodroplet by coalescence of clusters (nuclei) and smaller crystals. The energy released during coalescence is sufficient to anneal the clusters into high-quality crystals. The process allows precise control of nanocrystal size by adjusting the initial concentration of diethylzinc in heptane. The “as grown” nanocrystals exhibit size-dependent luminescence, narrow and symmetric emission, good monodispersity (confirmed by TEM analysis), and excellent photochemical stability. The technique is currently being extended to the synthesis of CdSe nanocrystals with promising preliminary results.
Information-Theoretic Lower Bounds on the Oracle Complexity of Stochastic Convex Optimization

Relative to the large literature on upper bounds on complexity of convex optimization, lesser attention has been paid to the fundamental hardn4516420ess of these problems. Given the extensive use of convex optimization in machine learning and statistics, gaining an understanding of these complexity-theoretic issues is important. In this paper, we study the complexity of stochastic convex optimization in an oracle model of computation. We introduce a new notion of discrepancy between functions, and use it to reduce problems of stochastic convex optimization to statistical parameter estimation, which can be lower bounded using information-theoretic methods. Using this approach, we improve upon known results and obtain tight minimax complexity estimates for various function classes.
Ecosystem Resilience to Disruptions Linked to Global Climate Change: An Adaptive Approach to Federal Land Management

Global climate change presents daunting challenges to the federal government’s ability to manage its lands and resources in ways that ensure that the priceless natural heritage that these land and resources comprise remains available in substantially unimpaired condition to both present and future generations of Americans. One of the challenges results from the fact that the laws governing the activities of federal land management agencies have outlasted the scientific assumptions on which those laws were based. In particular, Congress adopted many of those laws on the assumption that ecological systems tend toward a natural equilibrium. Subsequently, the science of ecology experienced a paradigm shift which recognizes that disturbances are a natural and necessary part of ecosystems. Natural resource management efforts that fail to consider the consequences of these disturbances are not likely to succeed at preserving the affected resources in the long term. This Article assesses the capability of the federal land management agencies under current law to deal with climate change and the threats it poses to federal lands and resources. It assesses whether the agencies’ organic statutes delegate to them sufficient authority to promote resilience in the natural resources they control, highlighting deficiencies in the nature, scope, and implementation of existing legislation. It makes a series of recommendations for changing either the statutes or the manner in which they are implemented to strengthen the capacity of the federal land management agencies to mitigate the impacts of climate change and avoid disruption or collapse of ecosystems in the face of it. The recommendations are designed to ensure that the land management agencies have ample authority to protect the resources for which they are responsible by managing them in an adaptive fashion, to promote ecosystem resilience and enhance their capacity to mitigate and adapt to climate change.
Effect of Molecular Structure on Liquid Slip

Slip behavior of three liquids with distinct molecular shapes—linear (hexadecane), branched (pentaerythritol tetra), and a chain of rings (polyphenylether)—is studied using molecular dynamics simulation and reduced-order modeling. Slip at a liquid-solid interface is shown to be affected by the molecular structure of the liquid. A two-dimensional Frenkel-Kontorova model captures the fundamental structural features of the liquid molecules and gives insight into how molecules flex and slip along the surface. We formulate an approximation to the Peierls-Nabarro energy which incorporates both the position of liquid atoms relative to substrate atoms and molecular flexibility. We find that increased molecular flexibility can lead to reduced slip by allowing the liquid to conform epitaxially to the substrate with only a small energetic penalty. Liquid molecules which are less flexible can conform to the substrate only with greater expense of conformational energy, and so exhibit larger slip.