cssi/SciSciGPT-SciSciNet huggingface dataset:
Mechanically Probing the Folding Pathway of Single RNA Molecules

We study theoretically the denaturation of single RNA molecules by mechanical stretching, focusing on signatures of the (un)folding pathway in molecular fluctuations. Our model describes the interactions between nucleotides by incorporating the experimentally determined free energy rules for RNA secondary structure, whereas exterior single-stranded regions are modeled as freely jointed chains. For exemplary RNA sequences (hairpins and the Tetrahymena thermophila group I intron), we compute the quasiequilibrium fluctuations in the end-to-end distance as the molecule is unfolded by pulling on opposite ends. Unlike the average quasiequilibrium force-extension curves, these fluctuations reveal clear signatures from the unfolding of individual structural elements. We find that the resolution of these signatures depends on the spring constant of the force-measuring device, with an optimal value intermediate between very rigid and very soft. We compare and relate our results to recent experiments by Liphardt et al. (2001).
High-Temperature Deformation and Diffusion in Oxides

High-temperature, steady-state deformation is usually controlled by diffusion of the slowest moving ion along its fastest diffusion path. Therefore, measurements of steady-state deformation can, in principle, be used to obtain information concerning diffusion. This paper will briefly review the assumptions that relate creep, defect chemistry, and diffusion. Steady-state deformation of the NaCI-structured oxides, Co{sub 1-x}O and Mn{sub l-x}O, and the perovskite-structured high-temperature superconductors YBa{sub 2}Cu{sub 3}0{sub x} and Bi{sub 2}Sr{sub 2}CaCu{sub 2}0{sub x} will be discussed, emphasizing diffusion of the minority defects.
Tighter Worst-Case Bounds on Algebraic Gossip

Gossip and in particular network coded algebraic gossip have recently attracted attention as a fast, bandwidth-efficient, reliable and distributed way to broadcast or multicast multiple messages. While the algorithms are simple, involved queuing approaches are used to study their performance. The most recent result in this direction shows that uniform algebraic gossip disseminates k messages in O(Δ(D + k + log n)) rounds where D is the diameter, n the size of the network and Δ the maximum degree. In this paper we give a simpler, short and self-contained proof for this worst-case guarantee. Our approach also allows to reduce the quadratic Δ D term to min{3n, Δ D}. We furthermore show that a simple round robin routing scheme also achieves min{3n, Δ D} + Δ k rounds, eliminating both randomization and coding. Lastly, we combine a recent non-uniform gossip algorithm with a simple routing scheme to get a O(D + k + log^{O(1)}) gossip information dissemination algorithm. This is order optimal as long as D and k are not both polylogarithmically small.
A 4-GHz 130-nm address generation unit with 32-bit sparse-tree adder core

This paper describes a 32-bit address generation unit designed for 4-GHz operation in 1.2-V 130-nm technology. The AGU utilizes a 152-ps sparse-tree adder core to achieve 20% delay reduction, 80% lower interconnect complexity, and a low (1%) active energy leakage component. The dual-V/sub T/ semidynamic implementation of the adder core provides the performance of a dynamic CMOS design with an average energy profile similar to static CMOS, enabling 71% savings in average energy with a good sub-130-nm scaling trend.
The working set model for program behavior

Probably the most basic reason behind the absence of a general treatment of resource allocation in modern computer systems is an adequate model for program behavior. In this paper a new model, the “working set model,” is developed. The working set of pages associated with a process, defined to be the collection of its most recently used pages, provides knowledge vital to the dynamic management of paged memories. “Process” and “working set” are shown to be manifestations of the same ongoing computational activity; then “processor demand” and “memory demand” are defined; and resource allocation is formulated as the problem of balancing demands against available equipment.
Contingent government liabilities : a hidden risk for fiscal stability

This paper points out that Governments are facing increasing fiscal risks and uncertainties. Two of the reasons for this situation are: first, the international integration of financial markets, which has meant greater volumes and volatility of cross-border flows of private capital; and, second, the privatization of state functions, accompanied by implicit or explicit state guarantees. The third reason is that policymakers pursuing a balanced budget or some deficit target tend to favor off-budget forms of state support that do not require immediate cash and that, at least for some time, hide the underlying fiscal cost. This paper first classifies and analyzes the potential obligations and fiscal risks governments face and their sources. It next outlines the options for reducing fiscal risks in the context of fiscal adjustment, with particular attention to the typology and analysis of specific fiscal risks, the high risk exposure of governments of transition and emerging-market economies, and the quality and bias in government decision-making at the time of fiscal adjustment. Several questions are addressed. How can policymakers be made accountable for recognizing the long-term cost of all forms of government activities? How can the moral hazard induced by government interventions be reduced? What standards for public sector accounting, budgeting, reporting, and risk management would foster sound fiscal performance in the long term?
Tax Collection in History

This article examines the rich variety of tax collection methods that have been employed throughout history. Three general categories have been observed: share contracts, rent contracts, and wage contracts, which differ depending on whether the government needs to measure the actual tax collected, the tax base, or the collector's effort, respectively. We develop a principal—agent model that seeks to explain the choice among these forms based on collector incentives, the value of state-specific collection effort, and measurement costs. We then review the actual use of the various forms in light of the model, both across countries and over time.
Structure of entanglement at deconfined quantum critical points

We study the entanglement propertes of deconfined quantum critical points. We show not only that these critical points may be distinguished by their entanglement entropy but also that they are in general more highly entangled that conventional critical points. We primarily focus on computations of the entanglement entropy of deconfined critical points in $2+1$ dimensions, drawing connections to topological entanglement entropy and a recent conjecture on the monotonicity under RG flow of universal terms in the entanglement entropy. We also consider in some detail a variety of issues surrounding the extraction of universal terms in the entanglement entropy. Finally, we compare some of our results to recent numerical simulations.
A Balanced Look at Self-Employment Transitions Later in Life

After a demographic holiday that lasted nearly two decades, America is now showing signs of societal aging. Between 1990 and 2010, the percentage of the population aged 65 and over increased by only four tenths of a percentage point, from 12.6 to 13.0 percent (Hetzel & Smith, 2001; Werner, 2011). Since 2010, however, this percentage has increased from 13.0 to 14.1 percent and, in just 6 years, will rise to 16.8 percent (Ortman, Velkoff, & Hogan, 2014; U.S. Census Bureau, 2014). By 2030, approximately one in five Americans (20.3%) will be aged 65 or older. We are in the beginning stages of a rapidly aging society. The strains of societal aging are already apparent. Since 2010, the Social Security program’s (noninterest) revenues have been insufficient to cover outlays (Board of Trustees of OASDI, 2013; Table VI.A1) and, although unsupported in the economics literature, talk about older workers stealing jobs from younger ones is often reported in the popular press (Cahill, 2011; Dhanjal & Schirle, 2014; Gruber, Milligan, & Wise, 2009). In recent years, economic growth has stagnated and the labor market has failed to produce sufficient employment opportunities for younger workers (Congressional Budget Office, 2014). One partial solution to the strains of an aging society is continued work later in life (Munnell & Sass, 2008), and self-employment is one way that some older Americans have chosen to remain in the labor force. The individual and societal benefits of continued work are straightforward: each additional year that retirement is delayed is one additional year of earnings and possible savings and one fewer year that assets are spent down. Further, continued work later in life has been shown to maintain or improve the physical and mental health of older workers (Wang, 2007; Wink & James, 2012; Zhang, Wang, Liu, & Shultz, 2009). Looking ahead to the increasing effects of societal aging and a challenged labor market, and with the perception of intergenerational job competition, is self-employment a partial solution to both societal aging and a stagnant economy? In this brief article, we document some of the policy issues surrounding transitions into self-employment later in life.
Go (Con)figure: Subgroups, Imbalance, and Isolates in Geographically Dispersed Teams

Research regarding geographically dispersed teams (GDTs) is increasingly common and has yielded many insights regarding the effects of spatio-temporal and socio-demographic factors on GDT functioni...
Information-Theoretic Limits on Sparse Signal Recovery: Dense versus Sparse Measurement Matrices

We study the information-theoretic limits of exactly recovering the support set of a sparse signal, using noisy projections defined by various classes of measurement matrices. Our analysis is high-dimensional in nature, in which the number of observations n, the ambient signal dimension p, and the signal sparsity k are all allowed to tend to infinity in a general manner. This paper makes two novel contributions. First, we provide sharper necessary conditions for exact support recovery using general (including non-Gaussian) dense measurement matrices. Combined with previously known sufficient conditions, this result yields sharp characterizations of when the optimal decoder can recover a signal for various scalings of the signal sparsity k and sample size n, including the important special case of linear sparsity (k = ?(p)) using a linear scaling of observations (n = ?(p)). Our second contribution is to prove necessary conditions on the number of observations n required for asymptotically reliable recovery using a class of ?-sparsified measurement matrices, where the measurement sparsity parameter ?(n, p, k) ? (0,1] corresponds to the fraction of nonzero entries per row. Our analysis allows general scaling of the quadruplet (n, p, k, ?) , and reveals three different regimes, corresponding to whether measurement sparsity has no asymptotic effect, a minor effect, or a dramatic effect on the information-theoretic limits of the subset recovery problem.
Bicyclo[2.1.0]pentanes and Bicyclo[2.2.0]hexanes

1 Introduction 2 Synthesis 3 Physical Properties 4 Chemical Reactions Keywords: hydrocarbons and unsaturated and substituted derivative chemistry; ionization and oxidation potentials; highest-occupied molecular orbital (HOMO); antibonding Walsh orbital; State Theory or RRKM Theory; ring-opening transition structure; bimolecular reactions; transition metal complex reactions
Interference and Outage in Clustered Wireless Ad Hoc Networks

In the analysis of large random wireless networks, the underlying node distribution is almost ubiquitously assumed to be the homogeneous Poisson point process. In this paper, the node locations are assumed to form a Poisson cluster process on the plane. We derive the distributional properties of the interference and provide upper and lower bounds for its distribution. We consider the probability of successful transmission in an interference-limited channel when fading is modeled as Rayleigh. We provide a numerically integrable expression for the outage probability and closed-form upper and lower bounds. We show that when the transmitter-receiver distance is large, the success probability is greater than that of a Poisson arrangement. These results characterize the performance of the system under geographical or MAC-induced clustering. We obtain the maximum intensity of transmitting nodes for a given outage constraint, i.e., the transmission capacity (of this spatial arrangement) and show that it is equal to that of a Poisson arrangement of nodes. For the analysis, techniques from stochastic geometry are used, in particular the probability generating functional of Poisson cluster processes, the Palm characterization of Poisson cluster processes, and the Campbell-Mecke theorem.
Well-differentiated thyroid carcinomas: p53 mutation status and microvessel density

Background Risk-stratification schemes exist for well-differentiated thyroid carcinoma and include prognostic factors such as age, sex, extent of tumor, size of tumor, and presence of metastasis. Controversy continues, however, over the aggressiveness of initial surgical intervention because of anecdotal experiences of poor clinical outcomes in low-risk patients. Our objective is to determine the prognostic significance of two biologic tumor markers, the p53 gene mutation and CD34 microvessel density (MVD) count, in well-differentiated tumors of thyroid gland. Methods We selected 38 patients with well-differentiated thyroid carcinomas from the University of Illinois Tumor Registry. Patients had an average clinical follow-up of 10 years. Paraffin-embedded tumor specimens were available for all patients. Immunohistochemistry was performed to identify mutations of the p53 gene (Ab 1801) and to determine the MVD count (CD34). Results There were significant increases in MVD counts within thyroid tumor tissue, when compared with surrounding, normal thyroid tissue. There was no significant correlation noted, however, between increased MVD and histology or recurrence rates. There was a trend toward higher MVD counts in tumor specimens of patients initially seen with metastatic lymphadenopathy. The incidence of p53 mutation expression was 28%, and there was no correlation between p53 status and histology, sex, recurrence rate, or survival. Conclusions This study supports the concept of tumor neovascularization but fails to correlate MVD with clinical behavior or pathologic features in well-differentiated thyroid carcinoma. Furthermore, we found that the p53 mutation status was not an independent prognosticator of tumor behavior in these lesions. © 1998 John Wiley & Sons, Inc. Head Neck20: 152–158, 1998.
Measurements of temperature and seed atom density in high-speed MHD flows

Emission absorption measurements of temperature, potassium seed atom density, and electron conductivity have been demonstrated in the high-speed, turbulent coal-fired flow of a simulated MHD channel. A two-beam optical system provides coincident exposures of transmitted lamp and emission-only signals with a time resolution of one-half ms. Multiwavelength detection allows for optimization of the measurement wavelengths for a twowavelength analysis that eliminates error due to ash/slag particle extinction and emission. Previous measurements with single beam, 1 ms temporally separated measurements showed large standard deviations due to fluctuations in flow parameters between the two noncoincident exposures. Comparison of the two types of measurements for nominally the same flow conditions reveals the considerable improvement in measurement uncertainty with the two-beam optical system.
Interactions between closely coupled GaAs injection lasers

Interaction effects between injection lasers have been experimentally studied at 2°K and 77°K under pulse conditions in a single block configuration which permits close optical coupling between the lasers. This close coupling made previously reported effects an order of magnitude more prominent and revealed a new effect. The reduction of the threshold current of one laser by the influence of the coherent beam of a second laser by as much as a factor five has been observed. With respect to the quenching of one laser by a second laser, a quenching ratio (defined as the ratio of the quenched power to the quenching power) of 0.7 was obtained. A new effect observed was the reduction of the threshold current of one laser by the influence of the spontaneous emission from a second laser. A reduction of 10 per cent is typical for this effect. A qualitative discussion treating the two lasers as one optical cavity is given to incorporate these effects into one coherent picture. Logical device applications are also discussed.
Progress on solar absorber selective paint research

Abstract A considerable amount of effort has been expended by the Department of Energy (DOE) and by commercial interests to develop solar absorber selective paints; the goal is to develop an inexpensive, durable selective coating that has moderately good optical properties. This report is intended to focus on those research programs monitored by Los Alamos, the research efforts in progress at Los Alamos, durability evaluations, and the progress that has been made toward commercialization.
FINANCIAL LITERACY, FINANCIAL EDUCATION AND ECONOMIC OUTCOMES

In this article we review the literature on financial literacy, financial education, and consumer financial outcomes. We consider how financial literacy is measured in the current literature, and examine how well the existing literature addresses whether financial education improves financial literacy or personal financial outcomes. We discuss the extent to which a competitive market provides incentives for firms to educate consumers or offer products that facilitate informed choice. We review the literature on alternative policies to improve financial outcomes, and compare the evidence to evidence on the efficacy and cost of financial education. Finally, we discuss directions for future research.
The Chandra Iron-L X-Ray Line Spectrum of Capella

An analysis of the iron L-shell emission in the publicly available spectrum of the Capella binary system, as obtained by the High Energy Transmission Grating Spectrometer on board the Chandra X-Ray Observatory, is presented. The atomic-state model, based on the HULLAC code, is shown to be especially adequate for analyzing high-resolution X-ray spectra of this sort. Almost all of the spectral lines in the 10-18 A wavelength range are identified. It is shown that, for the most part, these lines can be attributed to emission from L-shell iron ions in the Capella coronae. Possibilities for electron temperature diagnostics using line ratios of Fe16+ are demonstrated. It is shown that the observed iron-L spectrum can be reproduced almost entirely by assuming a single electron temperature of kTe = 600 eV. This temperature is consistent both with the measured fractional ion abundances of iron and with the temperature derived from ratios of Fe16+ lines. A volume emission measure of 1053 cm-3 is calculated for the iron L-shell emitting regions of the Capella coronae, indicating a rather small volume of 1029 cm3 for the emitting plasma if an electron density of 1012 cm-3 is assumed.
An Improved Apparatus for Determining Moisture in Rubber by Distillation with Toluene

Abstract An improved apparatus has been developed for the determination of water in rubber by distillation with toluene. The volume of the water collected is measured in a graduated capillary tube, which allows more precise measurement than the tapered tube formerly used. The interior of the trap and condenser is coated with a water-repellent silicone polymer to prevent water droplets from adhering to the walls and to improve the accuracy. This paper describes the construction of the apparatus and a procedure for coating its interior with the silicone polymer. A method of calibration of the trap is included in a general procedure for use of the equipment.
MEMS TECHNOLOGY FOR ADVANCED TELECOMMUNICATION APPLICATIONS

MEMS (Micro Electro Mechanical Systems) technology is becoming a crucial enabling technology for optical and RF telecommunication applications due to the performance, cost and integration advantages. All-optical switches and silicon optical benches for optical network systems and RF MEMS components such as RF MEMS switches, tunable capacitors, high Q inductors, and thin film bulk acoustic resonators for miniaturized single chip RF transceivers are discussed. Despite all the promising aspects, practical problems to be addressed for successful commercialization are not trivial. By reviewing optical and RF MEMS research activities and some of the implementation examples, key success factors of MEMS components for the commercialization are discussed.
Fixed points of endomorphisms of a free metabelian group

We consider IA-endomorphisms (i.e. Identical in Abelianization) of a free metabelian group of nite rank, and give a matrix characterization of their xed points which is similar to (yet different from) the well-known characterization of eigenvectors of a linear operator in a vector space. We then use our matrix characterization to elaborate several properties of the xed point groups of metabelian endomorphisms. In particular, we show that the rank of the xed point group of an IA-endomorphism of the free metabelian group of rank n> 2 can be either equal to 0, 1, or greater than (n 1) (in particular, it can be innite). We also point out a connection between these properties of metabelian IA-endomorphisms and some properties of the Gassner representation of pure braid groups.
Democracy, foreign direct investment and natural resources

Abstract Empirical studies that examine the impact of democracy on foreign direct investment (FDI) assume that the relationship between democracy and FDI is the same for resource exporting and non-resource exporting countries. This paper examines whether natural resources in host countries alter this relationship. We estimate a linear dynamic panel-data model using data from 112 developing countries over the period 1982–2007. We find that democracy promotes FDI if and only if the value of the share of minerals and oil in total exports is less than some critical value. We identify 90 countries where an expansion of democracy may enhance FDI and 22 countries where an increase in democratization may reduce FDI. We also find that the effect of democracy on FDI depends on the size and not the type of natural resources.
The Interaction of Collinear Gaps of Arbitrary Charge in a Two Dimensional Dimer System

The correlation of gaps in dimer systems was introduced by Fisher and Stephenson (Phys Rev 132:1411–1431, 1963), who looked at the interaction of two monomers generated by the rigid exclusion of dimers on the closely packed square lattice. In previous work we considered the analogous problem on the hexagonal lattice, and we extended the set-up to include the correlation of any finite number of monomer clusters. For fairly general classes of monomer clusters we proved that the asymptotics of their correlation is given, for large separations between the clusters, by a multiplicative version of Coulomb’s law for 2D electrostatics. However, our previous results required that the monomer clusters consist (with possibly one exception) of an even number of monomers. In this paper we determine the asymptotics of general defect clusters along a lattice diagonal in the square lattice (involving an arbitrary, even or odd number of monomers), and find that it is given by the same Coulomb law. We also obtain a conceptual interpretation for the multiplicative constant as the product of the correlations of the individual clusters.
Reflections on Experimental Techniques in the Law

MUCH of the law's reasoning turns on the effects of the rules it creates or enforces. Normally these effects are alleged or implied, but rarely proven. Yet during the last decades, first the natural sciences and, learning from them, the social sciences have developed techniques of experimentation that would allow firmer determinations of what a rule of law does or does not accomplish.' The basic tool (and also the paradigm for retrospective analysis) is the controlled experiment. Its essence is simple: The objects or people on which the experiment is to be performed are divided randomly, that is, by some lottery device, into two groups; the experimental treatment is then applied to the one group and withheld from the other, the control group. If an effect is found in the experimental group that is absent from the control group, it can be attributed to the experimental treatment, since at the time of the prior random selection the two groups had been strictly comparable, and in fact interchangeable.2 And randomization assures that whatever the outcome of the experiment, it is possible to calculate the degree of certainty that can be attached to it.
General mirror pairs for gauged linear sigma models

We carefully analyze the conditions for an abelian gauged linear -model to exhibit nontrivial IR behavior described by a nonsingular superconformal eld theory determining a superstring vacuum. This is done without reference to a geometric phase, by associating singular behavior to a noncompact space of (semi-)classical vacua. We nd that models determined by reexive combinatorial data are nonsingular for generic values of their parameters. This condition has the pleasant feature that the mirror of a nonsingular gauged linear -model is another such model, but it is clearly too strong and we provide an example of a non-reexive mirror pair. We discuss a weaker condition inspired by considering extremal transitions, which is also mirror symmetric and which we conjecture to be sucient. We apply these ideas to extremal transitions and to understanding the way in which both Berglund-Hubsch mirror symmetry and the Vafa-Witten mirror orbifold with discrete torsion can be seen as special cases of the general combinatorial duality of gauged linear -models. In the former case we encounter an example showing that our weaker condition is still not necessary.
Mirabolic Robinson–Shensted–Knuth correspondence

The set of orbits of GL(V) in Fl(V) × Fl(V) × V is finite, and is parametrized by the set of certain decorated permutations in a work of Magyar, Weyman, and Zelevinsky. We describe a mirabolic RSK correspondence (bijective) between this set of decorated permutations and the set of triples: a pair of standard Young tableaux, and an extra partition. It gives rise to a partition of the set of orbits into combinatorial cells. We prove that the same partition is given by the type of a general conormal vector to an orbit. We conjecture that the same partition is given by the bimodule Kazhdan–Lusztig cells in the bimodule over the Iwahori–Hecke algebra of GL(V) arising from Fl(V) × Fl(V) × V. We also give conjectural applications to the classification of unipotent mirabolic character sheaves on GL(V) × V.
Political institutions and sovereign borrowing: evidence from nineteenth-century Argentina

I study the relationship between political institutions and sovereign borrowing when constitutional constraints are systematically chosen to obtain better credit conditions. I argue that the impact of institutional constraints on country risk premia depends on the gov- ernment's concern with the country's creditworthiness and its "willingness to repay"; two variables that are hardly observable. To properly evaluate the relationship between political institutions and sovereign borrowing, I focus on the link between institutional constraints and the risk premia of Argentine bonds between 1822 and 1913. Specifically, I analyze whether a "structural break" in the government's cost of borrowing time-series exists. I use the Perron-Volesang test for structural change with unknown break dates. The statistical analysis indicates that the adoption of institutional constraints led to significant improve- ments in borrowing terms: the series has a single structural change; and the distinctive break point is associated with the country's adoption of constitutional checks and balances. Time- series regressions and instrumental variables (IV) estimation reinforce these findings.
Health Insurance and Retirement of Married Couples

SUMMARY Most health insurance in the USA is provided by employers until eligibility for public health insurance (Medicare) begins at age 65. Retiring before 65 exposes workers who lack retiree health insurance coverage to the risk of catastrophic medical expenditure. We solve and estimate a dynamic model of the employment behavior of older married couples that includes risky medical expenditure and health insurance. Parameter estimates imply that the risk-reducing feature of health insurance can account for about half of the observed association between retiree health insurance and employment for married men, but can account for only one tenth of the much larger observed association for married women. Policy simulations imply very small effects on employment of changing the age of eligibility for Medicare from 65 to 67. Copyright  2006 John Wiley & Sons, Ltd.
Beyond Ricardo: Assignment Models in International Trade

International trade has experienced a Ricardian revival. In this article, we offer a user guide to assignment models, which we refer to as Ricardo-Roy (R-R) models, that have contributed to this revival.
Adjoints of ideals in regular local rings

The adjoint of an ideal I in a regular local ring R is the R-ideal adj(I):=H^0(Y, I\omega_Y), where f:Y -> Spec(R) is a proper birational map with Y nonsingular and IO_Y invertible, and \omega_f is a canonical relative dualizing sheaf. (Such an f is supposed to exist.) The basic conjecture is that I.adj(I^n)=adj(I^{n+1}) whenever n is >= the analytic spread of I. This is a strong version of the Briancon-Skoda theorem, implying all other known versions. It follows from the (conjectural) vanishing of H^i(Y,\omega_Y) for all i>0. When R is essentially of finite type over a char. 0 field, that vanishing has been deduced by Cutkosky from Kodaira vanishing. It also holds whenever dim.R = 2; and in this case we can say considerably more about adjoints, tying in e.g., with classical material on adjoint curves and conductors.
THE EVOLUTION OF AN IMPACT-GENERATED ATMOSPHERE

Shock wave and thermodynamic data for rock-forming and volatile-bearing minerals are used to determine minimum impact velocities (v_(cr)) and minimum impact pressures (p_(cr)) required to form a primary H_2O atmosphere during planetary accretion from chondritelike planetesimals. The escape of initially released water from an accreting planet is controlled by the dehydration efficiency. Since different planetary surface porosities will result from formation of a regolith, v_(cr) and p_(cr) can vary from 1.5 to 5.8 km/sec and from 90 to 600 kbar, respectively, for target porosities between 0 and ∼45%. On the basis of experimental data, hydration rates for forsterite and enstatite are derived. For a global regolith layer on the Earth's surface, the maximum hydration rate equals 6 × 10^(10) g H_2O sec^(−1) during accretion of the Earth. Attenuation of impact-induced shock pressure is modeled to the extent that the amount of released water as a function of projectile radius, impact velocity, weight fraction of water in the target, target porosity, and dehydration efficiency can be estimated. The two primary processes considered are the impact release of water bound in hydrous minerals (e.g., serpentine) and the subsequent reincorporation of free water by hydration of forsterite and enstatite. These processes are described in terms of model calculations for the accretion of the Earth. Parameters which lead to a primary atmosphere/hydrosphere are: an accretion time of ⪅ 1.6 × 10^8years, the use of an accretion model defined by Weidenschilling (1974, 1976), a mean planetesimal radius of 0.5 km, a hydration rate of 6 × 10^(10) g H_2O sec^(−1) inferred from a mean porosity of ∼ 10% for the upper 1 km of the accreting Earth, and values for the dehydration efficiency, DE, of 0.55 and 0.07 for the maximum and minimum pressure decay model, respectively. Conditions which prohibit the formation of a primary atmosphere include an accretion time much longer than 1.6 × 10^8 years, a hydration rate for forsterite and enstatite well in excess of 6 × 10^(10) g H_2O sec^(−1), and a dehydration efficiency DE < 0.07. We conclude that the concept of dehydration efficiency is of dominant importance in determining the degree to which an accreting planet acquires an atmosphere during its formation.
Feasibility of a Webinar for Coaching Patients With Chronic Obstructive Pulmonary Disease on End-of-Life Communication

Rationale: Previous research has shown that patients with chronic obstructive pulmonary disease (COPD) desire conversations about end-of-life wishes. However, most clinicians do not initiate these discussions. We explored whether educating patients via Web conferencing (webinar) would equip them with knowledge and skills to engage in conversations about end-of-life care. Results: Prewebinar, 6 of the 7 patients had completed advanced care planning forms but only half had shared these with their clinicians. Most patients felt confident about discussing end-of-life preferences. At 3 months, all participants had taken further action on end-of-life planning. Five felt the webinar was an acceptable option if unable to participate in person. All patients voiced that adding a video stream would have promoted interaction in the context of these sensitive conversations. Conclusions: This pilot project demonstrated that a webinar to educate patients on end-of-life communication was acceptable for the majority of pa...
Synthesis, characterization, and crystal structures of uranyl compounds containing mixed chromium oxidation states

The mixed-valence chromium uranyl compounds Li{sub 5}[(UO{sub 2}){sub 4}(Cr(V)O{sub 5})(Cr(VI)O{sub 4}){sub 4}](H{sub 2}O){sub 17} (1), (Mg(H{sub 2}O){sub 6}){sub 5}[(UO{sub 2}){sub 8}(Cr(V)O{sub 5}){sub 2}(Cr(VI)O{sub 4}){sub 8}] (2) and (NH{sub 4}){sub 5}[(UO{sub 2}){sub 4}(Cr(V)O{sub 5})(Cr(VI)O{sub 4}){sub 2}]H{sub 2}O{sub 11} (3) have been synthesized and characterized. Each contains an identical sheet of cation-centered polyhedra. Central to the connectivity of the sheet are four uranyl pentagonal bipyramids that share some of their equatorial vertices, giving a four-membered ring. The Cr(V) cation located near the center of this ring is coordinated by O atoms in a square pyramidal arrangement. The Cr(VI) is tetrahedrally coordinated by O atoms, and these tetrahedra link the four-membered rings of bipyramids. The mixed-valence nature of the sheet was verified by XANES, an EPR spectrum, and bond-valence analysis. Low-valence cations and H{sub 2}O groups reside between the sheets of uranyl and chromate polyhedra, where they provide linkages between adjacent sheets. - Graphical abstract: Three uranyl chromate compounds contain both pentavalent and hexavalent chromium. The unusual topology of the uranyl chromate sheet contains unusual pentavalent chromium in a square pyramidal coordination environment. Highlights: Black-Right-Pointing-Pointer The first uranyl compounds with mixed Cr valences are reported. Black-Right-Pointing-Pointer A sheet of uranyl polyhedra stabilizes pentavalentmore » chromium. Black-Right-Pointing-Pointer Uranyl and chromate polyhedra form a topologically novel sheet.« less
On estimating redshift and luminosity distributions in photometric redshift surveys

The luminosity functions of galaxies and quasars provide invaluable information about galaxy and quasar formation. Estimating the luminosity function from magnitude-limited samples is relatively straightforward, provided that the distances to the objects in the sample are known accurately; techniques for doing this have been available for about 30 yr. However, distances are usually known accurately for only a small subset of the sample. This is true of the objects in the Sloan Digital Sky Survey, and will be increasingly true of the next generation of deep multicolour photometric surveys. Estimating the luminosity function when distances are only known approximately (e.g. photometric redshifts are available, but spectroscopic redshifts are not) is more difficult. I describe two algorithms which can handle this complication: one is a generalization of the V max algorithm, and the other is a maximum likelihood approach. Because these methods account for uncertainties in the distance estimate, they impact a broader range of studies. For example, they are useful for studying the abundances of galaxies which are sufficiently nearby that the contribution of peculiar velocity to the spectroscopic redshift is not negligible, so only a noisy estimate of the true distance is available. In this respect, peculiar velocities and photometric redshift errors have similar effects. The methods developed here are also useful for estimating the stellar luminosity function in samples where accurate parallax distances are not available.
Exhaust of Underexpanded Jets from Finite Reservoirs

We examine the response of an underexpanded jet to a depleting, nite reservoir with experiments and simulations. An open-ended shock tube facility with variable reservoir length is used to obtain images of nitrogen and helium jet structures at successive instances during the blowdown from initial pressure ratios of up to 250. The reservoir and ambient pressures are simultaneously measured to obtain the instantaneous pressure ratio. We estimate the time-scales for jet formation and reservoir depletion as a function of the specic heat ratio of the gas and the initial pressure ratio. The jet structure formation time-scale is found to become approximately independent of pressure ratio for ratios greater than 50. In the present work, no evidence of time-dependence in the Mach disk shock location is observed for rates of pressure decrease associated with isentropic blowdown of a nite reservoir while the pressure ratio is greater than 15. The shock location in the nitereservoir jet can be calculated from an existing empirical t to innite-reserv oir jet data evaluated at the instantaneous reservoir pressure. For pressure ratios below 15, however, the present data deviate from a compilation of data for innite-reserv oir jets. A new t is obtained to data in the lower pressure regime. The self-similarity of the jet structure is quantied and departure from similarity is noted to begin at pressure ratios lower than about 15, approximately the same ratio which limits existing empirical ts.
The bottleneck model: An assessment and interpretation

The bottleneck model of congestion with endogenous scheduling has become a standard tool of transportation economics. It provides surprising insights about the time pattern of congestion, optimal pricing, and many distinct inefficiencies of unpriced equilibria including wrong departure order with heterogeneous preferences, wrong allocation of users across links of a network, and wrong order in which parking spaces are occupied. It illuminates the roles of travel-time reliability, traffic information, and extreme congestion (“hypercongestion”). It has been developed for use in practical network planning. Future use will probably emphasize greater realism, leading to more practical applications.
Photocatalytic Synthesis of Dihydrobenzofurans by Oxidative [3+2] Cycloaddition of Phenols

We report a protocol for oxidative [3+2] cycloadditions of phenols and alkenes applicable to the modular synthesis of a large family of dihydrobenzofuran natural products. Visible-light-activated transition metal photocatalysis enables the use of ammonium persulfate as an easily handled, benign terminal oxidant. The broad range of organic substrates that are readily oxidized by photoredox catalysis suggests that this strategy may be applicable to a variety of useful oxidative transformations.
A meta-control architecture for orchestrating policy enforcement across heterogeneous information sources

There is increasing demand from both organizations and individuals for technology capable of enforcing sophisticated, context-sensitive policies, whether security and privacy policies, corporate policies or policies reflecting various regulatory requirements. In open environments, enforcing such policies requires the ability to reason about the policies themselves as well as the ability to dynamically identify and access heterogeneous sources of information. This article introduces a semantic web framework and a meta-control model to orchestrate policy reasoning with the identification and access of relevant sources of information. Specifically, sources of information are modeled as web services with rich semantic profiles. Policy Enforcing Agents rely on meta-control strategies to dynamically interleave semantic web reasoning and service discovery and access. Meta-control rules can be customized to best capture the requirements associated with different domains and different sets of policies. This architecture has been validated in the context of different environments, including a collaborative enterprise domain as well as several mobile and pervasive computing applications deployed on Carnegie Mellon's campus. We show that, in the particular instance of access control policies, the proposed framework can be viewed as an extension of the XACML architecture, in which Policy Enforcing Agents offer a particularly powerful way of implementing XACML's Policy Information Point (PIP) and Context Handler functionality. At the same time, our proposed architecture extends to a much wider range of policies and regulations. Empirical results suggest that the semantic framework introduced in this article scales favorably on problems with up to hundreds of services and tens of service directories.
Molecular Disks in the Elliptical Galaxies NGC 83 and NGC 2320

The molecular gas in (some) early-type galaxies holds important clues to the history and the future of these galaxies. In pursuit of these clues, we have used the BIMA millimeter array to map CO emission in the giant elliptical galaxies NGC 83 and NGC 2320 and to search for CO emission from the S0 galaxy NGC 5838. We also present V and R images of NGC 83 and NGC 2320 that trace their dust distributions and enable a search for disky stellar structures. The molecular gas in NGC 83 is well relaxed, but both CO and dust in NGC 2320 show asymmetric structures that may be linked to a recent acquisition of the gas. However, the specific angular momentum distribution of molecular gas in NGC 2320 is consistent with that of the stars. Internal origin of the gas (stellar mass loss) cannot, therefore, be ruled out on angular momentum grounds alone. We also consider the evidence for star formation activity and disk growth in these two elliptical galaxies. Radio continuum and FIR fluxes of NGC 83 suggest star formation activity. NGC 2320 has bright [O III] emission, but its large radio-FIR flux ratio and the mismatch between the kinematics of CO and [O III] suggest that the ionized gas should not be attributed to star formation. The origin and future of these two CO-rich early-type galaxies are thus complex, multifaceted stories.
On-chip microdialysis system with in-line sensing capabilities

An on-chip microdialysis system with in-line sensing electrodes is presented here. The design of this system is based on membrane bonding onto microfluidic channels, having a high surface to volume ratio to promote efficient dialysis and in-situ integration with biosensors. Miniaturization of the microdialysis technique has several advantages including higher recovery of analytes, better estimation of local analyte concentration, and less invasive systems when used for continuous monitoring. The permeability of this system to glucose has been determined to be 2.5280 /spl mu/m/s (std: 0.3723 /spl mu/m/s) and 3.5543 /spl mu/m/s to small salt ions.
Minimum quality standard regulation under imperfect quality observability

Minimum quality standards (MQS) constitute an important regulatory tool that can be used to raise product qualities, to benefit consumers and to increase market participation. One of the main assumptions in the existing literature is that firms must comply with standards. Nevertheless, in many industries, and in particular the service industry, quality observability and enforceability are not perfect. Some low quality firms do not comply with standards. What are the welfare implications of an MQS regulation in such an environment? We develop a price competition model of vertical differentiation that accounts for these empirical observations. Contrary to well-established results in the literature, MQS can increase quality disparity between firms and raise hedonic prices. Some consumers get hurt and market participation decreases.
Ring Opening of 3‐Bromo‐2‐Isoxazolines to β‐Hydroxy Nitriles

Abstract 3‐Bromo‐2‐isoxazolines were converted to the corresponding β‐hydroxy nitriles by treatment with sodium iodide in the presence of either chlorotrimethylsilane or para‐toluenesulfonic acid. Both methods gave β‐hydroxy nitriles under relatively mild conditions in good to moderate yields for a variety of substituted 3‐bromo‐2‐isoxazolines.
Modeling, Analysis, and Optimal Design of the Automotive Transmission Ball Capsule System

Clutch shift control is critical for the performance and fuel economy of automotive transmissions, including both automatic and hybrid transmissions. Among all the factors that influence clutch shift control, clutch fill and clutch engagement are crucial to realize a fast and smooth clutch shift. When the clutch is not engaged, the fluid held by the centrifugal force inside of the clutch chamber, which introduces additional pressure that will affect the subsequent clutch fill and engagement processes, should be released. To realize this function, a ball capsule system is introduced and mounted on the clutch chamber. When the clutch chamber is ready to be filled for engagement, the ball capsule needs to close quickly and remain closed until the clutch is disengaged. It is also desirable to have an appropriate closing velocity for the ball capsule to minimize noise and wear. In this paper, the ball capsule dynamics is modeled, in which the derivation of the ball capsule throttling area is considered novel and critical because of its asymmetrical nature. Through this, the ball capsule’s intrinsic positive feedback structure is also revealed, which is considered to be the key to realize a fast response. Moreover, through the system dynamics analysis, the slope angle of the capsule is found to be an effective control parameter for system performance and robustness. To this end, the optimal shape of the capsule is designed using dynamic programming to achieve the desired performance.
Effect of Base Sequence and Hydration on the Electronic and Hole Transport Properties of Duplex DNA: Theory and Experiment †

An experimental investigation and theoretical study of the duplex DNA sequences d(5′-GAGG-3′)‚ d(3′-CTCC-5′) and d(5′-GTGG-3′)‚d(3′-CACC-5′) was carried out. The experiments show that the efficiency of radical cation transport, revealed by strand cleavage after treatment with piperidine, is the same in both sequences. Density functional theory (DFT) calculations reveal essentially identical ionization potentials and hole distributions for these sequences when they are properly hydrated. The effect of hydration on the electronic properties of these sequences was examined theoretically. Calculations on dry DNA (i.e., having no water molecules) gives “phantom” electronic transitions to orbitals associated with the sodium counterions. However, these transitions vanish even with a minimal level of hydration. Meaningful theoretical results for DNA are obtained only when the counterions and hydrating water molecules are properly considered.