cssi/SciSciGPT-SciSciNet huggingface dataset:
Negative ion density fronts

Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te≫Ti). The boundary separating a plasma containing negative ions, and a plasma without negative ions, is usually thin so that the negative ion density falls rapidly to zero—forming a negative ion density front. Theoretical, experimental, and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow) are reviewed. During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the c...
Response of an Asymmetric Missile to Spin Varying through Resonance

Asymptotic expansions of maximum response angle as well as resonance response angles are derived for constant spin acceleration and for spin acceleration to steady-state spin. These show that the important parameter to be considered is the ratio of missile damping rate to the square root of spin acceleration at resonance. Predictions of the approximate theory are compared with exact numerical calculation for a variety of missiles, and excellent agreement is seen for moderately damped missiles.
Combustion of water-in-oil emulsion layers supported on water

In situ combustion of a water-in-oil emulsion layer supported on water is a complex process. In this paper, the combustion process of water-in-oil emulsion layers floating on top of a water body, as in the case of in situ burning of oil spilled at sea that has turned into emulsion, is modeled by using comprehensive mathematical treatment, and the results are compared with data obtained in our lab. The burning process model is divided into three regimes, as follows: 1. The initial regime begins when the emulsion layer floating on the ocean surface receives heat flux from an external source, such as an igniter or a burning oil pool; 2. The intermediate regime begins from the instant of the first appearance of an oil layer on the top of the emulsion layer due to breaking of the emulsion and continues until the oil starts to evaporate; 3. The final regime begins with the combustion of oil vapor, and ends when the fire extinguishes. The laboratory tests were conducted: 1) to establish a critical (i.e., minimum) external heat flux value to cause self-sustaining combustion of the emulsion layer for various emulsion compositions, and 2) to generate burn rate and other emulsion pool fire characteristics, such as time for emulsion separation, burn rate, burn time, and residue volume left. Measurements were made for emulsions of commercial no. 2 diesel oil, having 20% to 80% water by volume. The model was solved numerically by using finite difference method. Predictions from the model match well with the data.
Fundamental Performance Limits of Carbon Nanotube Thin-Film Transistors Achieved Using Hybrid Molecular Dielectrics

In the past decade, semiconducting carbon nanotube thin films have been recognized as contending materials for wide-ranging applications in electronics, energy, and sensing. In particular, improvements in large-area flexible electronics have been achieved through independent advances in postgrowth processing to resolve metallic versus semiconducting carbon nanotube heterogeneity, in improved gate dielectrics, and in self-assembly processes. Moreover, controlled tuning of specific device components has afforded fundamental probes of the trade-offs between materials properties and device performance metrics. Nevertheless, carbon nanotube transistor performance suitable for real-world applications awaits understanding-based progress in the integration of independently pioneered device components. We achieve this here by integrating high-purity semiconducting carbon nanotube films with a custom-designed hybrid inorganic–organic gate dielectric. This synergistic combination of materials circumvents conventiona...
Mars exploration rovers entry, descent, and landing trajectory analysis

In this study we present a novel method of land surface classification using surface-reflected GPS signals in combination with digital imagery. Two GPS-derived classification features are merged with visible image data to create terrain-moisture (TM) classes, defined here as visibly identifiable terrain or landcover classes containing a surface/soil moisture component. As compared to using surface imagery alone, classification accuracy is significantly improved for a number of visible classes when adding the GPS-based signal features. Since the strength of the reflected GPS signal is proportional to the amount of moisture in the surface, use of these GPS features provides information about the surface that is not obtainable using visible wavelengths alone. Application areas include hydrology, precision agriculture, and wetlands mapping.
A Simple Proof of the Fredholm Alternative and a Characterization of the Fredholm Operators

(2001). A Simple Proof of the Fredholm Alternative and a Characterization of the Fredholm Operators. The American Mathematical Monthly: Vol. 108, No. 9, pp. 855-860.
Positive predictive value of CT urography in the evaluation of upper tract urothelial cancer

OBJECTIVE. The purpose of this study was to determine the positive predictive value of CT urography in the diagnosis of upper tract urothelial malignancies.MATERIALS AND METHODS. Retrospective review of the records of patients who underwent 2,602 CT urographic examinations revealed that 81 (3%) examinations of 77 patients had findings suggesting upper tract urothelial cancer. Two radiologists in consensus categorized the findings as large masses (> 5 mm), small masses (≤ 5 mm), or urothelial thickening. The positive predictive value of CT urography was determined with the findings at pathologic examination (n = 42), followup imaging (n = 29), or clinical follow-up alone (n = 5). One patient with insufficient follow-up information was excluded. The effects of age, sex, indication for examination, imaging appearance, and urine cytology were analyzed with the Fisher's exact test or Student's t test. Multivariate logistic regression analysis was used to generate a model for predicting the probability of the p...
Ethnicity, Security, and Separatism in India

A hallmark of Indian politics, ethnic tension have escalated dramatically since the 1980s, endangering India's unity as a sovereign democracy. Although a succession of governments has attempted to resolve them, these conflicts have weakened India's role as the dominant power in the region. This work examines the connections between internal and external policy and explores the ways in which domestic tensions, particularly arising from ethnic and sectarian heterogenity, shape India's role in the region. The book studies movements in Punjab, Kashmir and Tamil Nadu, which escalated throughout the 1980s and influenced India's relations with Pakistan and Sri Lanka. It argues that India does not seek hegemony in South Asia; instead it acts to protect its nation-building efforts from similar problems faced by neighbouring countries. Paradoxically, this goal requires India to intervene in neighbouring countries ethnic conflicts.
Frequency Response Analysis of Fluid Control Systems for Parabolic Trough Solar Collectors

Previous studies of solar collector fluid control systems have utilized computer simulations of collector and piping dynamics to evaluate stability and response characteristics. To obtain reasonable simulation accuracy requires substantial computer memory and time, and is well beyond the capability of small desk-top computers. Here a linearized steady state frequency response is derived for parabolic trough collectors and for connecting piping, which can be used in standard gain-phase analyses to evaluate system stability and closed loop frequency response. The frequency response characteristics of a typical collector string and piping are used in a gain-phase analysis to get some insight into the effect on system stability of various system parameters such as controller gain, sensor and controller time constants, and sensor location.
Formation and isolation of simple, stable, acyclic di- and tripeptide hemiacetals

Abstract Di- and tripeptide aldehydes were found to undergo reaction with methanol to afford the corresponding methyl hemiacetals. These compounds, which possessed unusual stability, were isolated and characterized using NMR techniques and a chemical correlation experiment.
Parameter counting in relativistic mean-field models

Abstract Power counting is applied to relativistic mean-field energy functionals to estimate contributions to the energy from individual terms. New estimates for isovector, tensor, and gradient terms in finite nuclei are shown to be consistent with direct, high-quality fits. The estimates establish a hierarchy of model parameters and identify how many parameters are well constrained by bulk nuclear observables. We conclude that four (possibly five) isoscalar, non-gradient parameters, one gradient parameter, and one isovector parameter are well determined by the usual bulk nuclear observables.
Neutrino flavor oscillations without flavor mixing angles

Abstract We demonstrate that sizable neutrino flavor oscillations can be generated in a model with large extra spacetime dimensions even if the physics on the brane is flavor-diagonal, the bulk neutrino theory is flavor-neutral, and the brane/bulk couplings are flavor-blind. This is thus a compact model for addressing neutrino flavor oscillations in higher dimensions. We also discuss several phenomenological aspects of the “bulk-mediated” neutrino oscillations inherent in this model, and show that this model contains some potentially important new phenomenological features in the limit of large brane/bulk coupling.
Predictive Bcl-2 Family Binding Models Rooted in Experiment or Structure

Proteins of the Bcl-2 family either enhance or suppress programmed cell death and are centrally involved in cancer development and resistance to chemotherapy. BH3 (Bcl-2 homology 3)-only Bcl-2 proteins promote cell death by docking an α-helix into a hydrophobic groove on the surface of one or more of five pro-survival Bcl-2 receptor proteins. There is high structural homology within the pro-death and pro-survival families, yet a high degree of interaction specificity is nevertheless encoded, posing an interesting and important molecular recognition problem. Understanding protein features that dictate Bcl-2 interaction specificity is critical for designing peptide-based cancer therapeutics and diagnostics. In this study, we present peptide SPOT arrays and deep sequencing data from yeast display screening experiments that significantly expand the BH3 sequence space that has been experimentally tested for interaction with five human anti-apoptotic receptors. These data provide rich information about the determinants of Bcl-2 family specificity. To interpret and use the information, we constructed two simple data-based models that can predict affinity and specificity when evaluated on independent data sets within a limited sequence space. We also constructed a novel structure-based statistical potential, called STATIUM, which is remarkably good at predicting Bcl-2 affinity and specificity, especially considering it is not trained on experimental data. We compare the performance of our three models to each other and to alternative structure-based methods and discuss how such tools can guide prediction and design of new Bcl-2 family complexes.
Uniqueness of Nash equilibrium for linear-convex stochastic differential games

The uniqueness of Nash equilibria is shown for a class of stochastic differential games where the dynamic constraints are linear in the control variables. The result is applied to an oligopoly.
Effects Of Whole Body Vibration On Vertical Jump Performance Following Exercise Induced Muscle Damage

Enhancing vertical jump performance is critical for many sports. Following high intensity training, individuals often experience exercise induced muscle damage (EIMD). Many recovery modalities have been tested with conflicting results. The purpose of this investigation was to determine the effect of whole-body vibration (WBV) on vertical jump performance following EIMD. 27 females volunteered for 7 sessions and were randomly assigned to a treatment or control group and administered each testing day. Vertical jump performance was assessed via vertical jump height (VJH), peak power output (PPO), rate of force development (RFD), relative ground reaction force (GRFz), and peak activation ratio of the vastus medialis (VM) via electromyography (EMG) before and after 3 days of EIMD via split squats. Two testing sets were collected each day, consisting of pre measures followed by WBV or control, and then post second measures. A 2x8 (group x time) mixed factor analysis of variance (ANOVA) was conducted for each variable. No significant interactions or group differences were found in any variable. Significant main effects for time were found in any variable, indicating performance declined following muscle damage. These results indicate that WBV does not aid in muscle recovery or vertical jump performance following EIMD.
Prospects for the Detection of Electromagnetic Counterparts to Gravitational Wave Events

Various models for electromagnetic emissions correlated with the gravitational wave signals expected to be detectable by the current and planned gravitational wave detectors are studied. The position error on the location of a gravitational wave source is estimated and used to show that it could be possible to observe the electromagnetic counterparts to neutron star-neutron star or neutron star-black hole binary coalescences detected with the Advanced Laser Interferometer Gravitational Wave Observatory (LIGO) and the Virgo detectors.
Minimal dynamical triangulations of random surfaces

We introduce and investigate numerically a minimal class of dynamical triangulations of two-dimensional gravity on the sphere in which only vertices of order five, six or seven are permitted. We show firstly that this restriction of the local coordination number, or equivalently intrinsic scalar curvature, leaves intact the fractal structure characteristic of generic dynamically triangulated random surfaces. Furthermore the Ising model coupled to minimal twodimensional gravity still possesses a continuous phase transition. The critical exponents of this transition correspond to the usual KPZ exponents associated with coupling a central charge c = 1 model to two-dimensional gravity. That two-dimensional (2D) quantum gravity can be regularized and studied using dynamical triangulations (DT) is well known [1] and has lead to extensive study of the properties of dynamically triangulated random surfaces (DTRS). Indeed, many of the properties of critical spin systems on such lattices have been shown to follow from continuum treatments of central charge c < 1 theories coupled to 2D-quantum gravity. Furthermore, this formulation has the advantage that it renders tractable the calculation of many features of these theories which are inaccessible to continuum methods. Foremost amongst these are questions related to the quantum geometry and fractal structure of the typical 2D manifolds appearing in the partition function [2]. It has often been speculated that some of these models should also find a realization in condensed matter physics as models of membranes and/or interfaces with fluid in-plane degrees of freedom. The problem in trying to map such problems onto dynamically triangulated models, however, has always been the occurrence of large vertex coordination numbers in an arbitrary random graph – real condensed matter systems typically place a cut-off on the number of interactions allowed by the microscopic degrees of freedom. It is possible that such cut-offs are unimportant in the
Adaptive image matching in the subband domain

In this paper we discuss image matching by correlation in the subband domain with prospective applications. Theoretical proof is given to show that the correlation of two signals equals the weighted sum of the correlations of their decomposed subband signals. We propose an adaptive method to compute image correlation directly in the subband domain, which avoids decoding of the compressed data. Compared with pixel-domain correlation, this method reduces computation by more than ten times with satisfactory accuracy. We also compare the effects of template size, number of iterations of subband decomposition, and filter type on the speed and accuracy. Complexity estimations and test results are given. In addition, several techniques that involve image correlation are investigated for application in image matching.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
The pyroelectric thin film sensor: A novel tool for the analysis of thin films

Abstract A novel pyroelectric thin film sensor with a subnanosecond response time is described. The use of this device as detector for radiation-induced thermal wave phenomena is then discussed and this detection scheme compared with more established photoacoustic and photothermal techniques. This detector provides at negligible cost a unique combination of extreme time resolution with utmost sensitivity. This sensor is compatible with most media: ultrahigh vacuum, air, most liquids and a large variety of excitation sources can be utilized together with this detector. Photons throughout the entire spectral range from radio waves to X-rays, electrons, ions and neutral particles have been used to probe the sample property of interest. When using a pulsed laser for excitation of a sample that is directly deposited onto the pyroelectric element the spectral resolution and temporal and spatial definition of the pulsed laser can be combined with the high sensitivity and large bandwidth of the pyroelectric sensor. This unique combination of advantageous features makes this technique the method of choice for most applications in the area of thin films. Examples emphasizing the versatility and the unique properties of this new detection scheme as well as its inherent limitations are discussed. Typical applications in the thermal analysis and spectroscopy of thin films are reviewed.
Remarkable facilitation of hetero-cycloisomerizations with water and other polar protic solvents: metal-free synthesis of indolizines

Hetero-cycloisomerization reactions of propargylic alcohol derivatives leading to indolizines have been demonstrated to proceed in the presence of water alone. This stands as a significant advance over the previous methods using Pt, Cu or Ag salts paired with ligands in organic solvents such as benzene, acetonitrile or methylene chloride.
Poisson limits for a hard-core clustering model

Abstract Let X1n,…,X>nn denote the locations of n points in a bounded, γ-dimensional, Euclidean region Dn which has positive γ-dimensional Lebesgue measure μ(Dn). Let {Yn(r): r > 0} be the interpoint distance process for these points where Yn(r) is the number of pairs of points(Xin, Xin) which with i in‖ ƒ(x 1 …x 1 )= C n exp (vy n (r)) if y n (r 0 )=0, 0 if y n (r 0 )>0 where r0 is a positive constant and Cn is a normalizing constant. These joint densities modify the Strauss [11] clustering model densities by introducing a hard-core component (no two points can have ‖Xin − Xin‖ μ(D n ) n 2 converges to a positive constant and the boundary of Dn is negligible are essentially equivalent to requiring that although the number of points n is large the region is large enough so that the points are sparse in this region. That is, it is rare for a point to have another point close to it. These results extend results for v ⩽ 0 given by Saunders and Funk [9] where it is shown that without the hard core component such results do not hold for v > 0. Statistical applications are discussed.
The Double-Edged Sword of Independence: Inoculating Electoral Reform Commissions Against Everyday Politics

Whenever academics and policymakers think about how to design electoral reform commissions, they almost always emphasize the importance of independence - the need to ward off the infection of politics and shut self-interested legislators, special interest groups, and political parties out of the decisionmaking process. The modest point of this essay is that independence is a double-edged sword. Giving electoral reform commissions too much independence may undermine the likelihood that reform will ever take root. That is because a central dilemma for most reform commissions is that its members must play politics in order to change the way politics will ultimately be played. This essay therefore argues that rather than quarantine electoral reform commissions from everyday politics, we ought to inoculate them. Inoculation, of course, requires one to be infected with the very disease one seeks to avoid. My proposal is thus to infuse the decisionmaking process with some of the concerns that dominate everyday politics. The first half of this essay lays out the empirical grounds for believing that fully independent decisionmaking bodies can sometimes be less effective at achieving reform than institutions that are partially enmeshed in the political system. The second half of the essay offers a first cut at the more difficult question raised by this essay: how do we strike the proper balance between political infection and political quarantine, between engagement and independence? Because any such analysis depends heavily on context, this part sketches some general considerations while focusing on the experience of the British Columbia Citizens' Assembly as a case study.
Bulk physics at a graviton factory

Abstract A general prediction of the 5-d Randall–Sundrum (RS) hierarchy model is the emergence of spin-2 Kaluza–Klein (KK) gravitons with weak scale masses and couplings. The lowest order effective theory of the RS model is given by 5-d Einstein gravity which uniquely fixes the self-interactions of gravitons. We demonstrate that large numbers of light KK resonances could be produced at a future lepton-collider-based “Graviton Factory”. Measuring the self-interactions of these KK gravitons will probe the accuracy of the 5-d Einstein gravity picture and, in addition, yield indirect information on the as yet untested self-coupling of the 4-d graviton. The self-interactions of the gravitons can be studied by measuring the decays of the heavier states to the lighter ones. Using the AdS/CFT picture, these can be interpreted as the decays of heavier resonances to lighter ones, in a strongly coupled 4-d CFT. We show that these decays have sufficient rates to be studied at future colliders and that they are also, in principle, sensitive to higher derivative operators, such as the Gauss–Bonnet term. In a generalized RS model, with non-universal 5-d fermion masses, FCNC's will be induced. We show that precise measurements of the rare decays of KK graviton/gauge states into flavor non-diagonal final states at a Graviton Factory can be used to map the 5-d fermion mass matrix.
Energy dispersive spectroscopy using synchrotron radiation: Intensity considerations

Abstract Detailed considerations are given to the reliability of energy dependent integrated intensity data collected from the pressure cavity of a diamond-anvil pressure cell illuminated with heterochromatic radiation from a synchrotron storage ring. It is demonstrated that, at least in one run, the electron beam current cannot be used to correct for energy-intensity variations of the incident beam. Rather, there appears to be an additional linear relationship between the decay of the synchrotron beam and the magnitude of the background intensity.
Preparation of Dibenzo[e,g]isoindol-1-ones via Scholl-Type Oxidative Cyclization Reactions

A flexible synthesis of dibenzo[e,g]isoindol-1-ones has been developed. Dibenzo[e,g]isoindol-1-ones represent simplified benzenoid analogues of biological indolo[2,3-a]pyrrolo[3,4-c]carbazol-5-ones (indolocarbazoles), compounds that have demonstrated a wide range of biological activity. The synthesis of the title compounds involved tetramic acid sulfonates. Different aryl groups were introduced at C4 of the heterocyclic ring via Suzuki–Miyaura cross-coupling reactions. Finally, mild Scholl-type oxidative cyclizations mediated by phenyliodine(III) bis(trifluoroacetate) (PIFA) converted some of the latter compounds into the corresponding dibenzo[e,g]isoindol-1-ones. A systematic study of the oxidative cyclization revealed the following reactivity trend: 3,4-dimethoxyphenyl ≫ 3-methoxyphenyl > 3,4,5-trimethoxyphenyl > 4-methoxyphenyl ≈ phenyl. Overall, the oxidative cyclization required at least two methoxy groups distributed in the aromatic rings, at least one of which had to be located para to the site of the cyclization.
Strength and genericity of singularities in Tolman–Bondi–de Sitter collapse

We study the curvature strength and visibility of the central singularity arising in Tolman–Bondi–de Sitter collapse. We find that the singularity is visible and Tipler strong along an infinite number of timelike geodesics, independently of the initial data, and thus stable against perturbations of the latter.
The calibration of a sit-ups task using the Rasch Poisson Counts model.

The purpose of this study was to calibrate a nationally used sit-ups test using the Rasch Poisson Counts model and evaluate the model-data fit. The total number of subjects was 8,723, consisting of 4,486 girls and 4,237 boys, ages 10 to 18. The estimated difficulty of the sit-ups task was −2.80, which was appropriate for a majority of examinees whose ability levels ranged from.09 to 1.39. After the calibration, boys and girls as well as different age groups were compared under the same metric. Graphs of the model-data fit demonstrated that the model-data fit at a low ability level was not as good as the fit at a high ability, which could be caused by violation of assumptions of the model that examinees have the same performance speed throughout the test and that the speed at a given time is independent of the number of sit-ups completed so far. Key words: item response theory, modeling of motor performance, fitness testing
A Compressed PCA Subspace Method for Anomaly Detection in High-Dimensional Data

Random projection is widely used as a method of dimension reduction. In recent years, its combination with standard techniques of regression and classification has been explored. Here, we examine its use for anomaly detection in high-dimensional settings, in conjunction with principal component analysis (PCA) and corresponding subspace detection methods. We assume a so-called spiked covariance model for the underlying data generation process and a Gaussian random projection. We adopt a hypothesis testing perspective of the anomaly detection problem, with the test statistic defined to be the magnitude of the residuals of a PCA analysis. Under the null hypothesis of no anomaly, we characterize the relative accuracy with which the mean and variance of the test statistic from compressed data approximate those of the corresponding test statistic from uncompressed data. Furthermore, under a suitable alternative hypothesis, we provide expressions that allow for a comparison of statistical power for detection. Finally, whereas these results correspond to the ideal setting in which the data covariance is known, we show that it is possible to obtain the same order of accuracy when the covariance of the compressed measurements is estimated using a sample covariance, as long as the number of measurements is of the same order of magnitude as the reduced dimensionality. We illustrate the practical impact of our results in the context of predicting volume anomalies in Internet traffic data.
Three-Component Cycloadditions: The First Transition Metal-Catalyzed [5+2+1] Cycloaddition Reactions

Prompted by our studies of transition metal-catalyzed [4+4], [4+2], [5+2], and [6+2] cycloadditions and by the view that these two-component reactions could be intercepted by a third component of one or more atoms, a new three-component transition metal-catalyzed cycloaddition is described. This new [5+2+1] cycloaddition proceeds in good to excellent yield and with high or complete regioselectivity with a variety of carbonyl-substituted alkynes to give bicyclo[3.3.0]octenone adducts, resulting from transannular closure of the intermediate eight-membered-ring cycloadduct. Effects of concentration, temperature, pressure, and catalyst loading on the efficiency of the reaction are discussed. This process provides access to complex building blocks for synthesis based on simple, readily available components.
Entrepreneurship in the Theory of the Firm

This paper develops micro-economic foundations for a theory of entrepreneurship and growth, focusing on innovation and opportunity as intermediate linkages between the two. Expanding upon points of tangency between Schumpeter and Coase, the paper argues that transactions costs are the glue that holds together entrepreneurial “new combinations.” Technological/organizational complexity of production is defined as the extent to which a technical decision by one unit within the firm affects the productive efficiency of other units. Where decreasing transactions costs tend to pull incumbent organizations apart, the possession of difficult to imitate production practices by the same organizations keeps them together. The dissolution of incumbent firms creates opportunities for entrepreneurs; the prospect of Schumpeterian rents provides the incentive to realize those opportunities.
Accretion of the ordinary chondrites

Abstract The narrow size distributions of silicate and metal particles in 19 unequilibrated ordinary chondrites and other textural properties of these meteorites strongly suggest that chondritic material was sorted before or during its accumulation in parent bodies. Gravitational sorting during accretion is possible, but the conditions which it requires are implausible. Aerodynamic sorting - exclusion of small and/or low-density particles from a planetesimal moving through a mixture of gas and dust - can account for the textures of ordinary chondrites. It may also explain observed variations of siderophile element contents among and within the three groups of ordinary chondrites.
Academic and Behavioral Outcomes Among the Children of Young Mothers

In this article we use newly available data from the National Longitudinal Survey of Youth to investigate the effects of early motherhood on academic and behavioral outcomes for children born to early child bearers. We find that early motherhood’s strong negative correlation with children’s test scores and positive correlation with children’s grade repetition is almost entirely explained by prebirth individual and family background factors of teen mothers themselves. However early childbearing is associated indirectly with reduced children’s test scores through its linkage to family size (and thus to child birth order). We find a different pattern in predicting fighting truancy early sexual activity and other problem behaviors among adolescent and young adult offspring. For these behaviors maternal age at first birth remains an important risk factor even after controlling for a wide range of background factors and maternal characteristics. These results highlight the diverse pathways through which teen parenting might influence subsequent child well-being and social performance. (authors)
The mini-computer: a new approach to computer design

When memories become many times faster than they are today at less cost, how will computers be organized? For those installations which require many times their current performance, present methods may suffice. However, there will be installations which don't need or can't use this much additional performance. How can they benefit from such improved memory design?
Reduplication and Reciprocity in Imagining Community: The Play of Tropes in a Rural Bangladeshi Moot

The trope of the "body politic" is reproduced in a Bengali popular court, or moot, not only through explicit submetaphors of that master metaphor but through a grammatical example of what Peirce called diagrammatic iconism. The iconism of reduplicated verbs with reciprocal meaning became pivotal in the metacommunicative negotiation of the agenda of a rural Bangladeshi moot. Such forms of iconicity analyzed here play traceable roles in particular imaginations of community and give us an opportunity to explore the accessibility of those imaginations to discursive consciousness. The article concludes that the tropes most powerfully shaping the discourse of the moot are those least accessible to metapragmatic consciousness, those that rhetorically contribute to the veiling of their own rhetoricity.
Vojta's inequality and rational and integral points of bounded degree on curves

Let . These results are obtained as consequences of an inequality of Vojta which generalizes the Roth–Wirsing theorem to curves.
Highly-ionized oxygen absorbers in the intergalactic medium

Recent ultraviolet and X-ray observations of intergalactic O VI and O VII absorption systems along lines of sight to bright quasars have opened a new window on to the 'warm-hot intergalactic medium'. These systems appear to provide a significant reservoir for baryons in the local Universe, and comparison to cosmological simulations suggests that their abundance roughly matches theoretical predictions. Here we use analytical arguments to elucidate the physical properties of the absorbers and their role in structure formation. We first show that if the absorbers result from structure-formation shocks, the observed column densities naturally follow from post-shock-cooling models, if we include fast-cooling shocks as well as those that cannot cool within a Hubble time. In this case, the known O vi absorbers should show stronger O VII absorption than expected from collisional-ionization equilibrium (and much more than expected for photoionized systems). We then argue that higher-temperature shocks will be spatially associated with more massive virialized objects even well outside the virial radius. Thus, the different oxygen ions will trace different structures; O VII absorbers are the most common because that ion dominates over a wide temperature range (corresponding to a large range in halo mass). If each dark matter halo is surrounded by a network of shocks with total cross-section a few times the size of the virialized systems, then we can reproduce the observed number densities of absorbers with plausible parameters. A simple comparison with simulations shows that these assumptions are reasonable, although the actual distribution of shocked gas is too complex for analytical models to describe fully. Our models suggest that these absorbers cannot be explained as a single-temperature phase.
Effective stress-energy tensors, self-force and broken symmetry

Deriving the motion of a compact mass or charge can be complicated by the presence of large self-fields. Simplifications are known to arise when these fields are split into two parts in what is known as a Detweiler–Whiting decomposition. One component satisfies vacuum field equations, while the other does not. The force and torque exerted by the (often ignored) inhomogeneous 'S-type' portion are analyzed here for extended scalar charges in curved spacetimes. This field has previously been shown to effectively renormalize a body's linear and angular momenta. We show here that if the geometry is sufficiently smooth, it actually shifts all multipole moments of the body's stress–energy tensor (and does nothing else). This greatly expands the validity of statements that the homogeneous R field determines the self-force and self-torque up to renormalization effects. The forces and torques exerted by the S field directly measure the degree to which a spacetime fails to admit Killing vectors inside the body. A number of mathematical results related to the use of generalized Killing fields are therefore derived, and may be of wider interest. As an example of their application, the effective shift in the quadrupole moment of a charge's stress–energy tensor is explicitly computed to lowest nontrivial order.
Systems Mapping of Consumer Acceptance of Agrifood Nanotechnology

Application of nanotechnology in the agrifood system and the rising number of nanofood products on the market are creating concerns among consumers and other stakeholders. These concerns and other potential barriers to the commercialization of agrifood nanotechnology products may limit the ability to capture its full potential. Understanding the emerging trends and the links between underlying values, expressed attitudes, and actual behaviors involving consumer acceptance of agrifood nanotechnology is important for governance, risk regulation, and the achievement of the full potential of agrifood nanotechnology. The purpose of the study was to use systems mapping to examine and analyze critical links between consumer acceptance of agrifood nanotechnology and factors such as trust, stakeholders, institutions, knowledge, and human environmental health risks. The study used a meta-analysis of the risk perception literature and solicited the opinions of experts to develop the systems map. Factors affecting consumer acceptance of agrifood nanotechnology are dynamic, complex, interactive, and interdependent, and consumer decisions to accept agrifood nanotechnology were found to be the results of complex feedback structure. This study suggests several consumer policy and programmatic levels in the system toward enhancing consumer acceptance of agrifood nanotechnology products where warranted.
Does Religion Affect Economic Growth and Happiness? Evidence from Ramadan*

We study the economic effects of religious practices in the context of the observance of Ramadan fasting, one of the central tenets of Islam. To establish causality, we exploit variation in the length of the fasting period due to the rotating Islamic calendar. We report two key, quantitatively meaningful results: 1) longer Ramadan fasting has a negative effect on output growth in Muslim countries, and 2) it increases subjective well-being among Muslims. We then examine labor market outcomes, and find that these results cannot be primarily explained by a direct reduction in labor productivity due to fasting. Instead, the evidence indicates that Ramadan affects Muslims’ relative preferences regarding work and religiosity, suggesting that the mechanism operates at least partly by changing beliefs and values that influence labor supply and occupational choices beyond the month of Ramadan itself. Together, our results indicate that religious practices can affect labor supply choices in ways that have negative implications for economic performance, but that nevertheless increase subjective well-being among followers.
Grand unification in RS1

Abstract We study unification in the Randall–Sundrum scenario for solving the hierarchy problem, with gauge fields and fermions in the bulk. We calculate the one-loop corrected low-energy effective gauge couplings in a unified theory, broken at the scale MGUT in the bulk. We find that, although this scenario has an extra dimension, there is a robust (calculable in the effective field theory) logarithmic dependence on MGUT, strongly suggestive of high-scale unification, very much as in the (4D) Standard Model. Moreover, bulk threshold effects are naturally small, but volume-enhanced, so that we can accommodate the measured gauge couplings. We show in detail how excessive proton decay is forbidden by an extra U(1) bulk gauge symmetry. This mechanism requires us to further break the unified group using boundary conditions. A 4D dual interpretation, in the sense of the AdS/CFT correspondence, is provided for all our results. Our results show that an attractive unification mechanism can combine with a non-supersymmetric solution to the hierarchy problem.
Operation and physics potential of Tevatron Run 2

Run 2 at the Fermilab Tevatron collider is now starting up. This article reviews the current performance of the upgraded CDF and DO detectors, and outlines the physics goals and prospects for this run.
Cx43 and mechanotransduction in bone

Bone adaptation to changes in mechanical stimuli occurs by adjusting bone formation and resorption by osteoblasts and osteoclasts, to maintain optimal bone mass. Osteocytes coordinate the actions of these cells on the bone surface by sensing mechanical forces and producing cytokines that increase or prevent osteoblast and osteoclast differentiation and function. Channels formed by connexins (Cxs) and, in particular, connexin 43 (Cx43) in osteoblasts and osteocytes are central part of this mechanism to control bone mass. Cx43 hemichannels are opened by fluid flow and mediate the anti-apoptotic effect of mechanical stimulation in vitro, suggesting that Cx43 participates in mechanotransduction. However, mice lacking Cx43 in osteoblasts and/or osteocytes show an increased anabolic response to loading and decreased catabolic response to unloading. This evidence suggests that Cx43 channels expressed in osteoblastic cells are not required for the response to mechanical stimulation, but mediate the consequence of lack thereof. The molecular basis of these unexpected responses to mechanical stimulation is currently under investigation.
Hybrid simulation of mode conversion at the magnetopause

[1] Two-dimensional hybrid simulations are used to investigate how fast-mode compressional waves incident on a magnetopause current layer mode convert both linearly and nonlinearly to short wavelength (k⊥ρi ∼ 1) kinetic Alfven waves near the Alfven resonance surface. The background magnetic fields on both sides of the current layer are parallel to each other and perpendicular to the magnetopause normal, corresponding to a northward interplanetary magnetic field. The simulations are performed in a 2-D plane (xz), where x is normal to the magnetopause and z is tilted by an angle, θ, relative to the magnetic field. We examine how the mode conversion depends on wave frequency ω0, wave vector, Alfven velocity profile (particularly the magnetopause width, D0), ion β in the magnetosheath, electron-to-ion temperature ratio, and incident wave amplitude. Kinetic effects resolve the resonance, and KAWs radiate back to the magnetosheath side of the current layer. The compressional wave absorption rate is estimated and compared with linear theory. Unlike the prediction from low-frequency theory of the Alfven resonance, KAWs are also generated in cases with θ = 0°, provided ω0 > 0.1Ω0, with Ω0 being the ion cyclotron frequency in the magnetosheath. As the incident wave amplitude is increased, several nonlinear wave properties are manifested in the mode conversion process. Harmonics of the driver frequency are generated. As a result of nonlinear wave interaction, the mode conversion region and its spectral width are broadened. The nonlinear waves provide a significant transport of momentum across the magnetopause and are associated with significant ion heating in the resonant region.
Zero thermal expansion in YbGaGe due to an electronic valence transition

Most materials expand upon heating. Although rare, some materials expand on cooling, and are said to exhibit negative thermal expansion (NTE); but the property is exhibited in only one crystallographic direction. Such materials include silicon and germanium1 at very low temperature (<100 K) and, at room temperature, glasses in the titania–silica family2, Kevlar, carbon fibres, anisotropic Invar Fe-Ni alloys3, ZrW2O3 (ref. 4) and certain molecular networks5. NTE materials can be combined with materials demonstrating a positive thermal expansion coefficient to fabricate composites exhibiting an overall zero thermal expansion (ZTE). ZTE materials are useful because they do not undergo thermal shock on rapid heating or cooling. The need for such composites could be avoided if ZTE materials were available in a pure form. Here we show that an electrically conductive intermetallic compound, YbGaGe, can exhibit nearly ZTE—that is, negligible volume change between 100 and 400 K. We suggest that this response is due to a temperature-induced valence transition in the Yb atoms. ZTE materials are desirable to prevent or reduce resulting strain or internal stresses in systems subject to large temperature fluctuations, such as in space applications and thermomechanical actuators.
Thermal Comptonization in compact sources and the cosmic X-ray background

We model thermal Compionization and e+e − pair production in high viscosity black hole accretion flows. We assume that magnetic fields are in equipartition with the energy density of the flow and that cyclotron radiation is the major source of seed soft photons. The electrons are assumed to receive a constant fraction of the gravitational energy. We find that the resulting spectra have a constant X-ray energy spectral index, α x ≅ 0, for accretion rates 0.5 ≳ \(\dot m\) ≳ 20. Here \(\dot m\) ≡ \(\dot M\)c22/L E , and LE is the Eddington luminosity. The spectra are cut off above ∼ 150 keV. Such spectra closely resemble that of the residual cosmic X-ray background (after subtraction of the contributions of the known classes of extragalactic sources if the background originated at a redshift z ∼ 4–5. Thus, the residual cosmic background can be explained by an early population of active galaxies emitting thermal Comptonized spectra, as originally suggested by Leiter and Boldt (1982).
EVIDENCE FOR AN INTERMEDIATE-MASS BLACK HOLE IN NGC 5408 X-1

We report the discovery with XMM-Newton of correlated spectral and timing behavior in the ultraluminous X-ray source (ULX) NGC 5408 X-1. An approx. 100 ksec pointing with XMM/Newton obtained in January, 2008 reveals a strong 10 mHz QPO in the > 1 keV flux, as well as flat-topped, band limited noise breaking to a power law. The energy spectrum is again dominated by two components, a 0.16 keV thermal disk and a power-law with an index of approx. 2.5. These new measurements, combined with results from our previous January 2006 pointing in which we first detected QPOs, show for the first time in a ULX a pattern of spectral and temporal correlations strongly analogous to that seen in Galactic black hole sources, but at much higher X-ray luminosity and longer characteristic time-scales. We find that the QPO frequency is proportional to the inferred disk flux, while the QPO and broad-band noise amplitude (root mean squared, rms) are inversely proportional to the disk flux. Assuming that QPO frequency scales inversely with black hole mass at a given power-law spectral index we derive mass estimates using the observed QPO frequency - spectral index relations from five stellar-mass black hole systems with dynamical mass constraints. The results from all sources are consistent with a mass range for NGC 5408 X-1 from 1000 - 9000 Stellar mass. We argue that these are conservative limits, and a more likely range is from 2000 - 5000 Stellar mass. Moreover, the recent relation from Gierlinski et al. that relates black hole mass to the strength of variability at high frequencies (above the break in the power spectrum), and the variability plane results of McHardy et al. and Koerding et al., are also suggestive of such a. high mass for NGC 5408 X-1. Importantly, none of the above estimates appears consistent with a black hole mass less than approx. 1000 Stellar mass for NGC 5408 X-1. We argue that these new findings strongly support the conclusion that NGC 5408 X-1 harbors an intermediate mass black hole.