cssi/SciSciGPT-SciSciNet huggingface dataset:
A dynamic model for health screening: misperceptions, feedback and long term trends in screening mammography

Implications of widespread mammography screening remain controversial, and major health organizations in the US adopt different guidelines reflecting significant variations in actual practice. Literature suggests that implementation of routine screening over the past 30 years has incurred less benefit and more harms than is formerly believed. The classical approach to setting guidelines is based on the statistical paradigm of Type-I and Type-II errors, seeking to find an evidence-based balance between sensitivity (and thus the risk of false positives) and specificity (and the risk of false negatives), given the costs and benefits of different outcomes. Clearly, however, a wide range of other considerations play important roles in determining both the formal guidelines and how these are implemented, interpreted and acted upon by providers, payers, patient advocacy groups, and other stakeholders and actors. Science and scientific evidence, including the processes that generate evidence, are embedded in and not independent of a social, economic and political system. In this study we develop the first explicit and integrated, broad boundary feedback theory around the dynamics of health screening. The theory we develop includes a decision-theoretic core around the costs and benefits of screening including the fundamental tradeoff between sensitivity and specificity. It also includes some of the sociopolitical feedbacks that condition formal guidelines, public perception, and the actual practice. To provide context, we use the mammography case as the motivating example, but our model is generic enough to be applicable to other contexts of population health screening, such as the prostate-specific antigen (PSA) screening. Our model is tightly grounded in empirical evidence base, and we use a mix of qualitative/quantitative methods and mainly system dynamics to explain the dynamic nature of the medical screening problem within the US context. This study is part of my PhD dissertation and funded by MIT.
The Impact of College Peers on Academic Performance: Evidence from a Natural Experiment in Chile

First year students at the Pontificia Universidad Catolica de Chile, one of the leading Chilean universities, are randomly assigned to their first semester college class groups. This paper takes advantage of this natural experiment in order to robustly estimate the impact of peer characteristics on undergraduate academic performance. The research hypothesis is that being assigned as a freshman to a group with more or less students from a same school, or from a given socioeconomic background, may result in very different patterns of adaptation, potentially impacting academic performance. This paper finds evidence which suggests that, contrary to the results found in most of the existing literature, the average college admission score of first semester classmates not only has no positive impact on the academic performance of undergraduate students, but may actually be negatively affecting their grades. Also, although there are some differences across degrees and secondary school types, in general undergraduate students are more likely to be dismissed, and have lower grades, when they share their first semester college class with a secondary schoolmate. Moreover, students assigned to first semester college classrooms with a higher concentration of classmates who attended the same secondary school(s) generally have significantly lower grades, and are less likely to graduate. Finally, students sharing their first semester college classroom with students from public or subsidized secondary schools are more likely to be dismissed due to poor academic performance. The fact that these peer effects are persistent in time points to the existence of a path dependence pattern, suggesting that this initial period in college is key for student adaptation. These findings have important implications for the design of policies intended to improve the adaptation of freshman college students and the access to higher education, suggesting that students would benefit from targeted first semester college class group assignment policies, as well as from additional transitional aid tailored to their profiles.
Scaling of laser-plasma interactions with laser wavelength and plasma size

Laboratory experiments on the wavelength scaling of laser-plasma interactions have thus far been restricted to relatively modest laser energies (EL ≤ 200 J), short pulse lengths (τL ≤ 2 nsec), and small focal spot diameters (d ≲, 200 µm). Thus the plasma sizes have been quite modest. Under these conditions, wavelength scaling data using Livermore’s Argus laser show classical absorption physics and little evidence of instabilities, in good agreement with simple models and with computer hydrodynamics calculations. Absorption and preheat behave much more favorably at short laser wavelengths.
Bidirectional PageRank Estimation: From Average-Case to Worst-Case

We present a new algorithm for estimating the Personalized PageRank PPR between a source and target node on undirected graphs, with sublinear running-time guarantees over the worst-case choice of source and target nodes. Our work builds on a recent line of work on bidirectional estimators for PPR, which obtained sublinear running-time guarantees but in an average-case sense, for a uniformly random choice of target node. Crucially, we show how the reversibility of random walks on undirected networks can be exploited to convert average-case to worst-case guarantees. While past bidirectional methods combine forward random walks with reverse local pushes, our algorithm combines forward local pushes with reverse random walks. We also discuss how to modify our methods to estimate random-walk probabilities for any length distribution, thereby obtaining fast algorithms for estimating general graph diffusions, including the heat kernel, on undirected networks.
National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for Utilization of Biochemical Markers in Acute Coronary Syndromes and Heart Failure

The National Academy of Clinical Biochemistry’s (NACB) Laboratory Medicine Practice Guidelines (LMPG) for use of cardiac markers in coronary artery diseases were published in July 19991. Since production of this initial document, numerous published studies and presented data have added significantly to the knowledge base for biochemical markers of cardiac injury. This increased knowledge has substantially expanded the scope of recommendations for biochemical marker utilization since the 1999 document, and in particular has required the inclusion of recommendations regarding biochemical markers that extend beyond myocardial necrosis. Toward addressing these advances and their impact on biochemical marker utilization in clinical practice, the NACB appointed a chair and members of …
Integral Grothendieck–Riemann–Roch theorem

We show that, in characteristic zero, the obvious integral version of the Grothendieck–Riemann–Roch formula obtained by clearing the denominators of the Todd and Chern characters is true (without having to divide the Chow groups by their torsion subgroups). The proof introduces an alternative to Grothendieck’s strategy: we use resolution of singularities and the weak factorization theorem for birational maps.
Effect of protein source on nitrogen balance and plasma amino acids in exercising horses

Plasma AA in horses fed either an all-hay or a hay and grain diet in a traditional format have not been investigated. Eight horses were divided into 2 groups: a hay group fed only grass hay or a hay and a grain group (HG) fed in a crossover design for two 5-wk periods. After the first period, horses were fasted overnight, followed by feeding with blood sampling every hour for 6 h. A 4-d total fecal and urine collection to evaluate N balance followed. A 10-d washout period separated the 5-wk feeding periods, during which horses switched diets. The second period was also followed by fasting, feeding, blood sampling, and a 4-d collection period. Horses consumed 840 g of CP in the hay group and 865 g of CP in the HG group. Horses in the hay group had a 2.4 ± 2.4 g/d N balance, which was not different from 0 (P = 0.34), whereas horses in the HG group had 5.4 ± 2.4 g/d N balance, which was different from 0 (P = 0.045). Fecal N excretion was greater for the hay group compared with the HG group (hay = 51.1 ± 1.3 g/d and HG = 45.5 ± 1.3 g/d; P = 0.011), and urine N excretion was greater for the HG group compared with the hay group (hay = 79.3 ± 2.8 g/d and HG = 89.2 ± 2.8 g/d; P = 0.026). Plasma AA concentrations were greater in the HG group compared with the hay group for Met (P = 0.001), Lys (P = 0.001), Ile (P = 0.047), Arg (P < 0.001), Gln (P = 0.009), and Orn (P = 0.002). Plasma concentrations were less for the HG group compared with the hay group for Thr (P < 0.001) and Ala (P < 0.001). Plasma concentrations of urea were greater for the HG group compared with the hay group (P < 0.001), whereas 3-methyl-histidine concentrations were greater for the hay group compared with the HG group (P < 0.001). The effect of diet on the excretion of N via feces vs. urine in the hay and HG groups is typical. The early increases in the plasma concentrations of Met, Val, Ile, Leu, Phe, Lys, Arg, and Ala during the postfeeding phase are most likely due to increased foregut digestibility as well as a greater quality AA profile in the grain. The greater concentrations of Thr, Leu, and Val later in the postfeeding phase for the hay group most likely reflects slower digestion because of prolonged consumption time compared with the HG group. Improved N balance observed in the HG group supports the fact that the HG group had more available AA via the AA profile and foregut digestibility of the HG diet. Despite the fact that both groups consumed similar amounts of CP, the AA profile and availability affected N balance.
Promises of Conic Relaxation for Contingency-Constrained Optimal Power Flow Problem

This paper is concerned with the security-constrained optimal power flow (SCOPF) problem, where each contingency corresponds to the outage of an arbitrary number of lines and generators. The problem is studied by means of a convex relaxation, named semidefinite program (SDP). The existence of a rank-1 SDP solution guarantees the recovery of a global solution of SCOPF. We prove that the rank of the SDP solution is upper bounded by the treewidth of the power network plus one, which is perceived to be small in practice. We then propose a decomposition method to reduce the computational complexity of the relaxation. In the case where the relaxation is not exact, we develop a graph-theoretic convex program to identify the problematic lines of the network and incorporate the loss over those lines into the objective as a penalization (regularization) term, leading to a penalized SDP problem. We perform several simulations on large-scale benchmark systems and verify that the global minima are at most 1% away from the feasible solutions obtained from the proposed penalized relaxation.
An enantioselective total synthesis and stereochemical revision of (+)-citrinadin B.

This manuscript describes an enantioselective synthesis of the naturally occurring alkaloid citrinadin B. The synthetic effort revealed an anomaly in the original structural assignment that has led to the proposal of a stereochemical revision. This revision is consistent with the structures previously reported for a closely related family of alkaloids, PF1270A–C. The synthesis is convergent and employs a stereoselective intermolecular nitrone cyloaddition reaction as a key step.
Distortions of the helicoid

Colding and Minicozzi have shown that an embedded minimal disk \({0\in\Sigma\subset B_R}\) in \({\mathbb{R}^3}\) with large curvature at 0 looks like a helicoid on the scale of R. Near 0, this can be sharpened: on the scale of |A|−1(0), Σ is close, in a Lipschitz sense, to a piece of a helicoid. We use surfaces constructed by Colding and Minicozzi to see this description cannot hold on the scale R.
Reciprocity in International Business: A Study of Telecommunications Alliances and Contracts

Reciprocity has been identified as a “messy” concept to study within international cooperative ventures. Theoretically grounded in international cooperation, transaction cost theory and economic anthropology, reciprocity is operationalized and explored in this study. Specifically, the effects of cultural distance, economic nearness, country-level risk and governance mechanisms are analyzed in relationship to three distinct measures of reciprocity. The international long distance industry provides the research setting. During the 1980s and 1990s, as this industry has become more competitive within the United States, foreign partners have been slow to reciprocate regarding the sharing of revenues derived from increased overseas calling. To study reciprocity between U.S. international long distance carriers and their partnering foreign entities, a pooled time-series/cross-sectional technique is used. 11 years of contractual arrangements between the U.S. firms and the telecom administrations of 109 countries are analyzed. Governance mechanisms test as highly significant with all measures of reciprocity, while the other independent variables exhibit varying degrees of significance with the respective dependent measures.
Optical waveguide taps on silicon CMOS circuits

As silicon CMOS circuit technology is scaled beyond the GHz range, both chipmakers and board makers face increasingly difficult challenges in implementing high speed metal interconnects. Metal traces are limited in density-speed performance due to the skin effect, electrical conductivity, and cross talk. Optical based interconnects have higher available bandwidth by virtue of the extremely high carrier frequencies of optical signals (> 100 THz). For this work, an effort has been made to determine an optimal optical tap receiver design for integration with commercial CMOS processes. Candidate waveguide tap technologies were considered in terms of optical loss, bandwidth, economy, and CMOS process compatibility. A new device, which is based on a variation of the multimode interference effect, has been found to be especially promising. BeamProp simulation results show nearly zero excess optical loss for the design, and up to 70% coupling into a 25 micrometer traveling wave CMOS photodetector device. Single-mode waveguides make the design readily compatible with wavelength multiplexing/demultiplexing elements. Polymer waveguide materials are targeted for fabrication due to planarization properties, low cost, broad index control, and poling abilities for modulation/tuning functions. Low cost, silicon CMOS based processing makes the new tap technology especially suitable for computer chip and board level interconnects, as well as metro fiber-to-the- home/desk telecommunications applications.
Heat Kernel on Homogeneous Bundles over Symmetric Spaces

We consider Laplace type partial differential operators acting on sections of homogeneous vector bundles over symmetric spaces. By using an integral representation of the heat semi-group we find a formal solution for the heat kernel diagonal that gives a generating function for the whole sequence of heat invariants. The obtained formal solution correctly reproduces the exact heat kernel diagonal after a suitable regularization and analytic continuation. This result is used to evaluate the nonperturbative low-energy effective action in quantum general relativity.
Conversion of α‐Amino Acids into Nitriles by Oxidative Decarboxylation with Trichloroisocyanuric Acid

Abstract Trichloroisocyanuric acid oxidation of α‐amino acids in water or methanol in the presence of pyridine produces nitriles with one less carbon in good yields and of high purity.
Stability Limits in Resonant Planetary Systems

The relationship between the boundaries for Hill and Lagrange stability in orbital element space is modified in the case of resonantly interacting planets. Hill stability requires the ordering of the planets to remain constant, while Lagrange stability also requires all planets to remain bound to the central star. The Hill stability boundary is defined analytically, but no equations exist to define the Lagrange boundary, so we perform numerical experiments to estimate the location of this boundary. To explore the effect of resonances, we consider orbital element space near the conditions in the HD 82943 and 55 Cnc systems. Previous studies have shown that, for nonresonant systems, the two stability boundaries are nearly coincident. However, the Hill stability formulae are not applicable to resonant systems, and our investigation shows how the two boundaries diverge in the presence of a mean-motion resonance, while confirming that the Hill and Lagrange boundaries are similar otherwise. In resonance the region of stability is larger than the domain defined by the analytic formula for Hill stability. We find that nearly all known resonant interactions currently lie in this unexpectedly stable region, i.e., where the orbits would be unstable according to the nonresonant Hill stability formula. This result bears on the dynamical packing of planetary systems, showing how quantifying planetary systems' dynamical interactions (such as proximity to the Hill stability boundary) provides new constraints on planet formation models.
Coordinated gripping of substrate by subunits of a AAA+ proteolytic machine

The construction of ClpX hexamers containing variable numbers and configurations of wild-type and grip-defective pore loops supports a model of concurrent loop movement that ensures substrate unfolding and translocation.
Loss of adhesion of a layer bonded to an elastic half space caused by a concentrated contact

A model is constructed to analyze the effects of a concentrated contact on a layer that is perfectly bonded to an elastic half space, except for a debond region, which is analyzed as a fractional interfacial crack. The crack is assumed not to open and the growth is governed by a mode II stress intensity factor that is retarded by interfacial friction. This model may be used to study the fracture of hard coatings at the asperity scale where the failure is caused by loss of adhesion of the interface. Two specific cases are considered: one in which the loading is by a point force and one in which the loading is by a finite size of contact about the size of the layer thickness. Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Baltimore, Maryland, October 16–19, 1988
Where Is the Dark Matter

How much dark matter is there in the universe and where is it located? These are two of the most fundamental questions in cosmology. We use in this paper optical and X-ray mass determinations of galaxies, groups, and clusters of galaxies to suggest that most of the dark matter may reside in very large halos around galaxies, typically extending to ~200 kpc for bright galaxies. We show that the mass-to-light ratio of galaxy systems does not increase significantly with linear scale beyond the very large halos suggested for individual galaxies. Rather, the total mass of large-scale systems such as groups and rich clusters of galaxies, even superclusters, can on average be accounted for by the total mass of their member galaxies, including their large halos (which may be stripped off in the dense cluster environment but still remain in the clusters) plus the mass of the hot intracluster gas. This conclusion also suggests that we may live in a low-density universe with Ω ~ 0.2-0.3.
IRON GRADIENTS IN COOLING FLOW GALAXIES AND GROUPS

Previous studies of the Fe abundances in the hot gas of galaxies and groups have reported con—icting results with most studies —nding very subsolar Fe abundances that disagree with standard theory. To investigate the possible role of Fe abundance gradients on these measurements we present deprojection analysis of the ROSAT PSPC data of 10 of the brightest cooling —ow galaxies and groups. The PSPC allows for spatially resolved spectral analysis on a half-arcminute scale, and interesting constraints on both the temperatures and Fe abundances are possible because the D1 keV temperatures of these systems are well matched to the bandpass of the PSPC. In nine out of 10 systems we —nd clear evidence that the Fe abundance decreases with increasing radius: within the central radial bin Z Fe B 1¨several Z _ kpc), which decreases to at the largest radii examined (r D 50¨100 kpc). The Fe (r ( 10 Z Fe D 0.5 Z _ abundances (and temperatures) are consistent with the average values for these systems that we obtained in our previous analyses of the ASCA data using multitemperature models, which con—rms that previous inferences of very subsolar Fe abundances from ASCA arise from the incorrect assumption of isothermal gas and not the presence of Fe abundance gradients. We discuss why this ii Fe bias ˇˇ aUects much more seriously the measurements of from ASCA data than from ROSAT data. We show that the Fe abun- Z Fe dance pro—les for these galaxies and groups are consistent with a gasdynamical model where the gas is enriched by stellar ejecta and supernovae in the ii solar supernova proportion,ˇˇ the stars formed with a Galactic initial mass function, and the gas is diluted by mixing with primordial gas at large radii. Subject headings: cooling —owsintergalactic mediumX-rays: galaxies
A community outreach lead screening program using capillary blood collected on filter paper.

Objective To test whether a method of fingerstick blood sample collection onto filter paper could be used as an alternative screening method in the field in settings where environmental lead contamination is a high risk. Method Members of the Pediatric Mobile Team of Children's Hospital of Michigan, Detroit, collected paired venous and capillary blood samples from 120 children, aged 6 months to 6 years, who presented for services at any of 7 sites located in decaying neighborhoods of older sections of Detroit. All samples were analyzed for lead content by graphite furnace atomic absorption spectrometry. Results When filter paper samples with blood lead levels of 0.48 µmol/L (10 µg/dL) or higher were compared with matched venous samples, the concordance coefficient was 0.96. The sensitivity and specificity of the filter paper samples relative to the venous samples for a cutoff of 0.48 µmol/L (10 µg/dL) or higher were 94% and 99%, respectively, with a positive predictive value of 97%. However, at a cutoff of 0.72 µmol/L (15 µg/dL), the sensitivity and specificity dropped to 75% and 98%, respectively, with filter paper samples underreporting blood lead values. At any cutoff point (0.48, 0.72, or 0.96 µmol/L [10, 15, or 20 µg/dL]), the filter paper method was highly specific for lead. Conclusions Capillary filter paper sampling is an accurate and practical alternative to venous sampling for blood lead screening using 0.48 µmol/L (10 µg/dL) as the cutoff. The filter paper method predicts levels of 0.72 µmol/L (15 µg/dL) or higher less well. The cause of divergent values above 0.72 µmol/L (15 µg/dL) is not clear. Environmental contamination of capillary filter paper, however, does not seem to be an explanation.
Isospin chemical potential and the QCD phase diagram at nonzero temperature and baryon chemical potential

Abstract We use the Nambu–Jona-Lasinio model to study the effects of the isospin chemical potential on the QCD phase diagram at nonzero temperature and baryon chemical potential. We find that the phase diagram is qualitatively altered by a small isospin chemical potential. There are two first order phase transitions that end in two critical endpoints, and there are two crossovers at low baryon chemical potential. These results have important consequences for systems where both baryon and isospin chemical potentials are nonzero, such as heavy ion collision experiments. Our results are in complete agreement with those recently obtained in a random matrix model.
A methodological issue concerning the use of Social Sciences Citation Index Journal Citation Reports impact factor data for journal ranking

Following a brief introduction of citation-based journal rankings as potential serials management tools, the most frequently used citation measure—impact factor—is explained. This paper then demonstrates a methodological bias inherent in averaging Social Sciences Citation Index Journal Citation Reports (SSCI JCR) impact factor data from two or more consecutive years. A possible method for correcting the bias, termed adjusted impact factor, is proposed. For illustration, a set of political science journals is ranked according to three different methods (crude averaging, weighted averaging, and adjusted impact factor) for combining SSCI JCR impact factor data from successive years. Although the correlations among the three methods are quite high, one can observe noteworthy differences in the rankings that could impact on collection development decisions.
A Reduced-Boundary-Function Method for Convective Heat Transfer With Axial Heat Conduction and Viscous Dissipation

We introduce a new method of solution for the convective heat transfer under forced laminar flow that is confined by two parallel plates with a distance of 2a or by a circular tube with a radius of a. The advection-conduction equation is first mapped onto the boundary. The original problem of solving the unknown field T(x,r,t) is reduced to seek the solutions of T at the boundary (r = a or r = 0, r is the distance from the centerline shown in Fig. 1), i.e., the boundary functions T{sub a}(x,t) {triple_bond} T(x,r=a,t) and/or T{sub 0}(x,t) {triple_bond} T(x,r=0,t). In this manner, the original problem is significantly simplified by reducing the problem dimensionality from 3 to 2. The unknown field T(x,r,t) can be eventually solved in terms of these boundary functions. The method is applied to the convective heat transfer with uniform wall temperature boundary condition and with heat exchange between flowing fluids and its surroundings that is relevant to the geothermal applications. Analytical solutions are presented and validated for the steady-state problem using the proposed method.
On Iron Enrichment, Star Formation, and Type Ia Supernovae in Galaxy Clusters

The nature of star formation and Type Ia supernovae (SNIa) in galaxies in the field and in rich galaxy clusters are contrasted by juxtaposing the buildup of heavy metals in the universe inferred from observed star formation and supernovae rate histories with data on the evolution of Fe abundances in the intracluster medium (ICM). Models for the chemical evolution of Fe in these environments are constructed, subject to observational constraints, for this purpose. While models with a mean delay for SNIa of 3 Gyr and standard initial mass function (IMF) are fully consistent with observations in the field, cluster Fe enrichment immediately tracked a rapid, top-heavy phase of star formation - although transport of Fe into the ICM may have been more prolonged and star formation likely continued beyond redshift 1. The means of this prompt enrichment consisted of SNII yielding greater than or equal to 0.1 solar mass per explosion (if the SNIa rate normalization is scaled down from its value in the field according to the relative number of candidate progenitor stars in the 3 - 8 solar mass range) and/or SNIa with short delay times originating during the rapid star formation epoch. Star formation is greater than 3 times more efficient in rich clusters than in the field, mitigating the overcooling problem in numerical cluster simulations. Both the fraction of baryons cycled through stars, and the fraction of the total present-day stellar mass in the form of stellar remnants, are substantially greater in clusters than in the field.
MULLERIAN ADENOSARCOMA OF THE UTERUS. AN ULTRASTRUCTURAL STUDY OF FOUR CASES

Four cases of uterine mullerian adenosarcoma, a distinctive form of mixed mullerian tumor, were studied by light and electron microscopy. All tumors showed the characteristic histologic pattern of benign neoplastic glands within sarcomatous stroma. Ultrastructurally, both mesenchymal and epithelial cells were seen. The mesenchymal cells showed some features of endometrial stromal cells, including the presence of intracytoplasmic collagen fibers. The epithelial cells formed glands, which resembled benign endometrial glands and were separated from the stroma by a well-defined basal lamina. No transitional cells between the epithelial and mesenchymal cells were seen. The ultrastructural features of these tumors suggest that the sarcomatous portion is of endometrial stromal origin. The glandular portion may arise, along with the stroma, from multipotential stem cells, or the glands may be non-neoplastic entrapped endometrial glands stimulated by the stroma and thus appearing to form an integral part of the tumor.
The Synthesis of 7-Alkoxyindoles

Abstract A number of protected 7-hydroxyindoles was prepared by reaction of the protected 2-nitrophenols with vinylmagnesium bromide. Benzhydryl was shown to be the protecting group of choice, giving good yields of the indole and being readily removed for subsequent transformations of the 7-hydroxy function.
Escape rates and variability constraints for high‐energy sodium sources at Mercury

[1] We present a 3-D time-dependent modeling of Mercury's extended sodium exosphere in the region of the distant tail. Recent simulations in support of the MESSENGER and BepiColombo missions have shown spatial distributions in Mercury's exosphere can be linked to specific source processes. Our model builds upon these efforts by concentrating on the escaping component of Mercury's surface-bound exosphere to assess the wide-field (7°) data described in the studies by Baumgardner et al. (2008) and Schmidt et al. (2010). Escape rates of several source processes in Mercury's exosphere are determined, and the effects of orbital motion, surface-gas interactions, variable source rates, and spatially heterogeneous sources are explored. Our simulations demonstrate that both photon-stimulated desorption and micrometeoroid impacts can result in a ∼20% loss of Mercury's sodium atmosphere, depending on orbital phase, and are jointly responsible for the observed comet-like tail as driven by solar radiation pressure. For a constant supply of both these sources into the exosphere, the modeled average column density over Mercury's disc decreases by ∼1/3 at 70° true anomaly (the orbital position for peak escape), consistent with observations over many orbits.
The Shiftrix-machine organization for high-speed digital computation

The need for higher speed computation demands continuous scrutiny of machine organization concurrent with the search for higher speed switching and storage elements.
Helical CR structures and sub-Riemannian geodesics

A helical CR structure is a decomposition of a real Euclidean space into an even-dimensional horizontal subspace and its orthogonal vertical complement, together with an almost complex structure on the horizontal space and a marked vector in the vertical space. We prove an equivalence between such structures and step-two Carnot groups equipped with a distinguished normal geodesic, and also between such structures and smooth real curves whose derivatives have constant Euclidean norm. As a consequence, we relate step-two Carnot groups equipped with sub-Riemannian geodesics with this family of curves. The restriction to the unit circle of certain planar homogeneous polynomial mappings gives an instructive class of examples. We describe these examples in detail.
Rationalization defeats itself: the limits to accounting's framing of economic life

This paper argues that the development of accounting can be well described as a process of rationalization. However, this need not imply the inexorable homogenization of economic activity, because beyond a certain point, rationalization defeats itself. Highly rationalized accounting leaves its users and creators disillusioned with it and inclined to exploit it as an abstract construct rather than to sustain it as a compelling system of knowledge. The paper explores the implications of this finding both for our understanding of how accounting influences economic life and for the future of the accounting profession.
Religion, religiosity and educational attainment of immigrants to the USA

This paper quantifies the association between religions, religiosity and educational attainment of new lawful immigrants to the US. This paper considers a broad set of religions that includes most of the major religions of the world. Using data from the New Immigrant Survey (2003), we show that affiliation with religion is not necessarily associated with an increase in educational attainment. Muslim and “Other religion” immigrants have less education compared to the immigrants who are not affiliated with any religion. However, affiliation with the Jewish religion is associated with higher educational attainment for males. With regard to religiosity, our results show that high religiosity is associated with lower educational attainment, especially for females. We also outline alternative frameworks that provide insight about the mechanisms that link religion and religiosity with educational attainment.
Advanced Wood- and Bio-Composites: Enhanced Performance and Sustainability

Use of wood-based-composites technology to create value-added commodities and traditional construction materials is generally accepted worldwide. Engineered wood- and lignocellulosiccomposite technologies allow users to add considerable value to a diverse number of wood- and lignocellulosic feedstocks including small-diameter timber, fast plantation-grown timber, agricultural fibre and lignocellulosic residues, exotic-invasive species, recycled lumber, and timber removals of hazardous forest-fuels. Another potential advantage of this type of economic- and materials-development scenario is that developing industrial composite processing technologies will provide producers an ability to use, and to adapt with, an ever-changing quality level of wood and/or other natural lignocellulosic feedstocks. However, the current level of performance of our state-of-the-art engineered composite products sometimes limit broader application into commercial, non-residential and industrial construction markets because of both real and perceived issues related to fire, structural-performance, and service-life. The worldwide research community has recognized this and is currently addressing each of these issues. From a performance standpoint, this developing knowledge has already and will continue to provide the fundamental understanding required to manufacture advanced engineered composites. From a manufacturing and a resource sustainability standpoint, with this evolving fundamental understanding of the relationships between materials, processes, and composite performance properties we now can in some cases, or may soon be able to, recognize the attributes and quality of an array of bio-based materials then adjust the composite manufacturing process to produce high-performance composite products. As this fundamental understanding is developed, we will increasingly be able to produce advanced, high-performance wood- and bio-composites. Then we must use those technologies as tools to help forest and land managers fund efforts to restore damaged eco-systems and which in turn may further promote sustainable forest management practices.
Socle degrees, resolutions, and Frobenius powers

Abstract We first describe a situation in which every graded Betti number in the tail of the resolution of R J may be read from the socle degrees of R J . Then we apply the above result to the ideals J and J [ q ] ; and thereby describe a situation in which the graded Betti numbers in the tail of the resolution of R / J [ q ] are equal to the graded Betti numbers in the tail of a shift of the resolution of R / J .
Propagating polar wind jets

Abstract Polar cap patches are regions of enhanced ionization that appear when the interplanetary magnetic field turns southward. They are created in the dayside cusp or equatorward of the cusp in the sunlit hemisphere. Once formed, they convect in an antisunward direction across the polar cap at the prevailing convection speed. The size of a plasma patch varies from about 200 to 1000 km, and its density relative to the background plasma density varies from a few percent to up to a factor of 100. A time-dependent, three-dimensional model of the coupled ionosphere–polar wind system was used to study the effect that a “representative” plasma patch has on the polar wind. The model indicates that the enhanced O + densities in the propagating plasma patch leads to enhanced H + densities. As the plasma patch convects across the polar cap, H + flows up and out of the topside ionosphere with a supersonic velocity. Therefore, a plasma patch looks like a horizontally propagating, vertically directed, polar wind jet. Since polar cap patches are common and since several are typically present at the same time, the ionospheric flux to the magnetosphere is perhaps much more structured than anticipated.
The Shape of gravity

In a non-trivial background geometry with extra dimensions, gravitational effects will depend on the shape of the Kaluza-Klein excitations of the graviton. We investigate a consistent scenario of this type with two positive tension three-branes separated in a five-dimensional anti-de Sitter geometry. The graviton is localized on the ``Planck'' brane, while a gapless continuum of additional gravity eigenmodes probe the infinitely large fifth dimension. Despite the background five-dimensional geometry, an observer confined to either brane sees gravity as essentially four-dimensional up to a position-dependent strong coupling scale, no matter where the brane is located. We apply this scenario to generate the TeV scale as a hierarchically suppressed mass scale. Arbitrarily light gravitational modes appear in this scenario, but with suppressed couplings. Real emission of these modes is observable at future colliders; the effects are similar to those produced by six large toroidal dimensions.
Market Provision of Broadcasting: A Welfare Analysis ∗

This paper presents a theory of the market provision of broadcasting and uses it to address the nature of market failure in the industry. Advertising levels may be too low or too high, depending on the nuisance cost to viewers, the substitutability of programs, and the expected benefits to advertisers from contacting viewers. Market provision may allocate too few or too many resources to programming and these resources may be used to produce programs of the wrong type. Monopoly ownership may produce higher social surplus than competitive ownership and the ability to price programming may reduce social surplus.
The Effect of Porosity on X-Ray Emission-Line Profiles from Hot-Star Winds

We investigate the degree to which the nearly symmetric form of X-ray emission lines seen in Chandra spectra of early-type supergiant stars could be explained by the possibly porous nature of their spatially structured stellar winds. Such porosity could effectively reduce the bound-free absorption of X-rays emitted by embedded wind shocks, and thus allow a more similar transmission of redshifted and blueshifted emission from the back and front hemispheres, respectively. To obtain the localized self-shielding that is central to this porosity effect, it is necessary that the individual clumps be optically thick. In a medium consisting of clumps of size l and volume filling factor f, we argue that the general modification in effective opacity should scale approximately as κeff ≈ κ/ , where, for a given atomic opacity κ and mean density ρ, the clump optical thickness scales as τc = κρl/f. For a simple wind structure parameterization in which the "porosity length" h ≡ l/f increases with local radius r as h = h'r, we find that a substantial reduction in wind absorption requires a quite large porosity scale factor, h' 1, implying large porosity lengths h r. The associated wind structure must thus have either a relatively large scale l r, or a small volume filling factor f ≈ l/r 1, or some combination of these. We argue that the relatively small-scale, moderate compressions generated by intrinsic instabilities in line driving are unlikely to give such large porosity lengths. This raises questions about whether porosity effects could play a significant role in explaining nearly symmetric X-ray line profiles, leaving the prospect of instead having to invoke a substantial (approximately a factor of 5) downward revision in the assumed mass-loss rates.
D-term inflation at the TeV scale and large internal dimensions

Abstract We show that D-term inflation at the TeV scale is possible in the presence of large internal dimensions. This requires very small couplings and masses which arise from the large size of the compact dimensions. We show that acceptable number of e-folds, magnitude and spectrum of density perturbations δρ/ρ and η can be obtained in this scenario at the price of a reheating temperature which is too high. Demanding an acceptable TR results in very small density perturbations.
Noble gas sputtering calculations using TRIM

Abstract In conjunction with our experimental work on sputtering with a saddle-field ion source, the Monte-Carlo program TRansport of Ions in Matter (TRIM) was applied to calculate the sputter yields for a variety of noble gas sputtering applications. Comparison with experiments are shown. Information extracted from these analyses have proved useful in optimizing the experimental sputtering parameters. Calculated sputter yields obtained utilizing TRIM are presented for noble gas sputtering of a variety of materials common to nuclear target preparation.
Structural Identification Using Inverse System Dynamics

A time-domain technique is presented which uses inverse structural dynamics to identify physical characteristics of a structure that can subsequently be used for damage detection. The term inverse refers to the fact that the roles of input and output are reversed from the usual forward system structural dynamics problem. If sensors such as accelerometers are placed at the external input locations, modal parameters corresponding to structural motion with the sensor locations fixed can be identified. One of the main advantages of this approach is that it only requires measured response data. This characteristic makes the approach applicable in cases where the input forces cannot be measured.
Enzymatic hydrolysis of biomass at high-solids loadings – A review

Abstract Enzymatic hydrolysis is the unit operation in the lignocellulose conversion process that utilizes enzymes to depolymerize lignocellulosic biomass. The saccharide components released are the feedstock for fermentation. When performed at high-solids loadings (≥15% solids, w/w), enzymatic hydrolysis potentially offers many advantages over conversions performed at low- or moderate-solids loadings, including increased sugar and ethanol concentrations and decreased capital and operating costs. The goal of this review is to provide a consolidated source of information on studies using high-solids loadings in enzymatic hydrolysis. Included in this review is a brief discussion of the limitations, such as a lack of available water, difficulty with mixing and handling, insufficient mass and heat transfer, and increased concentration of inhibitors, associated with the use of high solids, as well as descriptions and findings of studies that performed enzymatic hydrolysis at high-solids loadings. Reactors designed and/or equipped for improved handling of high-solids slurries are also discussed. Lastly, this review includes a brief discussion of some of the operations that have successfully scaled-up and implemented high-solids enzymatic hydrolysis at pilot- and demonstration-scale facilities.
Clinical implications of 2‐hydroxydesipramine plasma concentrations

The clinical utility of 2-hydroxydesipramine (2-OH-DMI) measurements was evaluated by examining the relationship of 2-OH-DMI concentrations in plasma to clinical outcome and side effects in depressed inpatients treated with desipramine (DMI). Studies were performed in responders and nonresponders to treatment and in patients experiencing subjective side effects or major adverse reactions necessitating interruption of treatment. Unlike DMI concentrations, 2-OH-DMI concentrations did not correlate with response. Summing the concentrations of parent drug and metabolite (DMI + 2-OH-DMI) did not improve the correlation over that achieved with DMI alone. Neither DMI, 2-OH-DMI, nor their sum correlated with subjective side effect totals or major adverse reactions. While our data do not permit any conclusions regarding the clinical activity of 2-OH-DMI, they suggest that its routine measurement in plasma is not likely to be useful in the management of depression. Clinical Pharmacology and Therapeutics (1983) 33, 183–189; doi:10.1038/clpt.1983.28
Synthesis of optically active 3-diazoacetylretinals with triisopropylphenylsulfonylhydrazone

Abstract An improved synthesis of photoaffinity labeled, optically active retinal derivatives is presented. A stable, easy to handle, glyoxalic acid 2,4,6,-triisopropylphenylsulfonylhydrazone (TIPPS) reacts with 3-hydroxyretinal to give the diazoacetylretinal analog in satisfactory yield.
Debris disk evolution around a stars

We report 24 and/or 70 μm measurements of ~160 A-type main-sequence stars using the Multiband Imaging Photometer for Spitzer (MIPS). Their ages range from 5 to 850 Myr, based on estimates from the literature (cluster or moving group associations) or from the H-R diagram and isochrones. The thermal infrared excess is identified by comparing the deviation (~3% and ~15% at the 1 σ level at 24 and 70 μm, respectively) between the measurements and the synthetic Kurucz photospheric predictions. Stars showing excess infrared emission due to strong emission lines or extended nebulosity seen at 24 μm are excluded from our sample; therefore, the remaining infrared excesses are likely to arise from circumstellar debris disks. At the 3 σ confidence level, the excess rate at 24 and 70 μm is 32% and ≥33% (with an uncertainty of 5%), considerably higher than what has been found for old solar analogs and M dwarfs. Our measurements place constraints on the fractional dust luminosities and temperatures in the disks. We find that older stars tend to have lower fractional dust luminosity than younger ones. While the fractional luminosity from the excess infrared emission follows a general 1/t relationship, the values at a given stellar age vary by at least 2 orders of magnitude. We also find that (1) older stars possess a narrow range of temperature distribution peaking at colder temperatures, and (2) the disk emission at 70 μm persists longer than that at 24 μm. Both results suggest that the debris disk clearing process is more effective in the inner regions.
Kern‐ und Radiochemie in den USA

Kernchemie ist eine lebendige Wissenschaft, leidet aber unter Nachwuchsmangel. Besonders problematisch ist die Situation in den USA, wo bereits die National Laboratories fur Undergraduates Sommerkurse in einem „National Security Internship Program” anbieten. Die Arbeitsgebiete fur Kernchemiker sind vielfaltig und reichen von der Kontrolle der Nichtverbreitung von Kernwaffen bis zu nuklearen Antriebssystemen fur Raumfahrtmissionen.