cssi/SciSciGPT-SciSciNet huggingface dataset:
Take-up of Medicare Part D: Results From the Health and Retirement Study

Objectives: To estimate the impact of Medicare Part D on prescription drug coverage among elderly Medicare benefi ciaries and to analyze the predictors of program enrollment (“take-up”) among those with no prior drug coverage. Methods: Multivariate analyses of data from the 2002, 2004, and 2006 waves of the Health and Retirement Study. Results: Take-up of Part D among those without drug coverage in 2004 was high; about 50%–60% of this group had Part D coverage in 2006. Only 7% of senior citizens lacked drug coverage in 2006 compared with 24% in 2004. Demand for prescription drugs was the most important determinant of the decision to enroll in Part D among those with no prior coverage. Many of those who remained without coverage in 2006 reported that they do not use prescribed medicines, and the majority had relatively low out-of-pocket spending. Conclusion: For the most part, Medicare beneficiaries seem to have been able to make economically rational deci sions about Part D enrollment despite the complexity of the program.
Chemoselective amide formation using O-(4-nitrophenyl)hydroxylamines and pyruvic acid derivatives.

A series of O-(4-nitrophenyl)hydroxylamines were synthesized from their respective oximes using a pulsed addition of excess NaBH3CN at pH 3 in 65–75% yield. Steric hindrance near the oxime functional group played a key role in both the ease by which the oxime could be reduced and the subsequent reactivity of the respective hydroxylamine. Reaction of the respective hydroxylamines with pyruvic acid derivatives generated the desired amides in good yields. A comparison of phenethylamine systems bearing different leaving groups revealed significant differences in the rates of these systems and suggested that the leaving group ability of the N–OR substituent plays an important role in determining their reactivity with pyruvic acid. Competition experiments (in 68% DMSO/phosphate buffered saline) using 1 equiv of N-phenethyl-O-(4-nitrophenyl)hydroxylamine and 2 equiv of pyruvic acid in the presence of other nucleophiles such as glycine, cysteine, phenol, hexanoic acid, and lysine demonstrated that significant che...
Optically-pumped mid-IR phosphor using Tm^3+-sensitized Pr^3+-doped KPb_2Cl_5

Efficient energy transfer at room temperature from Tm3+ to Pr3+ has been demonstrated in co-doped KPb2Cl5. Because of the low phonon energies in KPb2Cl5, the energy transfer processes result in the conversion of 805 nm laser diode pump energy to a broad band of mid-IR radiation between 3500to5500 nm. Energy transfer pathways, rates, and quantum efficiencies are evaluated. Results show that the material is suitable as a phosphor for the 4to5⁢ μm spectral range that can be optically pumped with low-cost 0.8⁢ μm laser diodes.
Manure Application Rules and Environmental Considerations

Abstract Three manure application limits – nitrogen limit, annual phosphorus limit, and multiple-year phosphorus limit (P Banking) are modeled to compare economic profitability and probability of application prior to a runoff causing rainfall event. Particular attention is given to the number of hours needed and available to distribute manure under each limit. Benefits are estimated as the foregone fertilizer applications. Costs are estimated based on the hours needed for manure management. The benefit and cost estimates indicate that P Banking was more profitable than nitrogen limit, which was more profitable than annual phosphorus limit. The number of hours required indicated that the annual phosphorus limit would not be completed within a five-week window approximately 2 of 10 years. If further restrictions based on precipitation forecasts were imposed, the likelihood of completion decreased to 6 of 10 years. The results of the study indicate that regulations that require annual phosphorus limit of manure cost the farmer and may have the unintended consequence of increasing runoff. P Banking would be the preferred manure application rule for both increasing farmer net income and reducing probability of application prior to a runoff causing rainfall event.
Microscopic black hole entropy in theories with higher derivatives

We discuss higher derivative corrections to black hole entropy in theories that allow a near horizon AdS3 × X geometry. In arbitrary theories with diffeomorphism in- variance we show how to obtain the spacetime central charge in a simple way. Black hole entropy then follows from the euclidean partition function, and we show that this gives agreement with Wald's formula. In string theory there are certain diffeomorphism anoma- lies that we exploit. We thereby reproduce some recent computations of corrected entropy formulas, and extend them to the nonextremal, nonsupersymmetric context. Examples include black holes in M-theory on K3 × T 2 , whose entropy reproduces that of the per- turbative heterotic string with both right and left movers excited and angular momentum included. Our anomaly based approach also sheds light on why exact results have been obtained in four dimensions while ignoring R 4 type corrections.
Nonlinear Frequency-Domain Analysis of Unsteady Flows in Turbomachinery with Multiple Excitation Frequencies

A harmonic balance technique for the analysis of nonlinear unsteady flows in turbomachiney arising from several excitation sources, possibly with frequencies with irrational ratios, is presented in this paper. This method uses a mixed time-domain/frequencydomain approach that allows one to model the blade row on a computational grid spanning just a single blade passage, no matter the interblade phase angles of the original disturbances. Using this approach, we compute several solutions, each one corresponding to one of several times over one period for periodic flows, or over a representative time interval for aperiodic flows. These time levels are coupled to each other through a spectral time derivative operator in the interior of the computational domain, and through the far-field and periodic boundary conditions around the boundary of the domain. In this paper, we apply the method to the two-dimensional Euler equations (although the method can be applied to three-dimensional and viscous flows), and examine the nonlinear interaction of wake passing with blade vibration.
NAVIGATION ACCURACY GUIDELINES FOR ORBITAL FORMATION FLYING

Some simple guidelines based on the accuracy in determining a satellite formation s semi-major axis differences are useful in making preliminary assessments of the navigation accuracy needed to support such missions. These guidelines are valid for any elliptical orbit, regardless of eccentricity. Although maneuvers required for formation establishment, reconfiguration, and station-keeping require accurate prediction of the state estimate to the maneuver time, and hence are directly affected by errors in all the orbital elements, experience has shown that determination of orbit plane orientation and orbit shape to acceptable levels is less challenging than the determination of orbital period or semi-major axis. Furthermore, any differences among the member s semi-major axes are undesirable for a satellite formation, since it will lead to differential along-track drift due to period differences. Since inevitable navigation errors prevent these differences from ever being zero, one may use the guidelines this paper presents to determine how much drift will result from a given relative navigation accuracy, or conversely what navigation accuracy is required to limit drift to a given rate. Since the guidelines do not account for non-two-body perturbations, they may be viewed as useful preliminary design tools, rather than as the basis for mission navigation requirements, which should be based on detailed analysis of the mission configuration, including all relevant sources of uncertainty.
The Small World of the American Corporate Elite, 1982-2001

This paper examines the degree of stability in the structure of the corporate elite network in the US during the 1980s and 1990s. Several studies have documented that board-to-board ties serve as a mechanism for the diffusion of corporate practices, strategies, and structures; thus, the overall structure of the network can shape the nature and rate of aggregate corporate change. But upheavals in the nature of corporate governance and nearly complete turnover in the firms and directors at the core of the network since 1980 prompt a reassessment of the network's topography. We find that the aggregate connec tivity of the network is remarkably stable and appears to be an intrinsic property of the interlock network, resilient to major changes in corporate governance. After a brief review of elite studies in the US, we take advantage of the recent advances in the theoretical and methodological tools for analyzing network structures to examine the network properties of the directors and companies in 1982, 1990,...
Local Gaussian Process Approximation for Large Computer Experiments

We provide a new approach to approximate emulation of large computer experiments. By focusing expressly on desirable properties of the predictive equations, we derive a family of local sequential design schemes that dynamically define the support of a Gaussian process predictor based on a local subset of the data. We further derive expressions for fast sequential updating of all needed quantities as the local designs are built up iteratively. Then we show how independent application of our local design strategy across the elements of a vast predictive grid facilitates a trivially parallel implementation. The end result is a global predictor able to take advantage of modern multicore architectures, providing a nonstationary modeling feature as a bonus. We demonstrate our method on two examples using designs with thousands of data points, and compare to the method of compactly supported covariances. Supplementary materials for this article are available online.
Neuroblastoma in Adults and Adolescents. An Indolent Course With Poor Survival

BACKGROUND Neuroblastoma rarely occurs in adults, and less than 10% of cases occur in patients older than 10 years. It has been suggested that the behavior of this disease may be different in older patients than in young children. The purpose of this study was to investigate the presentation, biologic features, and outcome of adolescent and adult patients with neuroblastoma to define differences from childhood neuroblastoma. METHODS Medical record and pathology reviews were conducted for 16 patients age 13 years or older (13-33 years) at diagnosis who presented with neuroblastoma at the University of California-San Francisco (UCSF) during the period 1968-1995 (patients with intracerebral tumors, esthesioneuroblastoma, or ganglioneuroma were excluded). Six of these patients received their original diagnosis at UCSF, and the others were referred after diagnosis. The survival for the same period for all neuroblastoma patients ages 13-18 years (n = 38) registered in the Children's Cancer Group (CCG) was compared with the survival for those ages 1-13 years (n = 1912). Three of the UCSF patients were enrolled in CCG studies. RESULTS Biologic characteristics observed in adolescents and adults differed from those observed in younger patients. In the UCSF population, only 6 of 15 tested patients age 13 or older had elevated urinary catecholamines, and 0 of 6 tested patients had MYCN amplification. There were two patients with Stage I disease, three with Stage II, two with Stage III, and nine with Stage IV. Primary sites were adrenal, pelvic, and retroperitoneal in four cases each; mediastinal in two cases; and paraspinal in two cases. Metastases in nine patients at diagnosis were observed in bone in five; in bone marrow in four; in lymph nodes in three; in the liver in two; and in the pleura, breast, and dura in one patient each. 131I-metaiodobenzylguanidine uptake was observed in 9 of 11 patients. Initial treatment included surgery for 13 of 16 patients, chemotherapy for 10 of 16, radiation therapy for 7 of 16, and autologous bone marrow transplantation for 1 of 16. Relapses occurred in 15 of 16 patients and death in 13 of 16, with overall survival 30% 5 years after diagnosis. Only 1 patient currently remains free of clinical disease 24 months after diagnosis. Several of these patients had long courses from diagnosis to death, with multiple recurrences and/or chronic, persistent disease. In the CCG data base, 76% of patients ages 13-18 years had metastatic disease at diagnosis. In this group, only 1 of 32 had MYCN amplification. The actuarial survival of all CCG patients ages 13-18 years was 7% at 5 years and 4% at 10 years, whereas that for patients ages 1-13 years was 30% at 5 years and 23% at 10 years. CONCLUSIONS Neuroblastoma in adolescents and adults has different biologic characteristics and a longer course than in children; nevertheless, ultimately the outcome is poor regardless of stage. A much more aggressive or innovative therapeutic approach is needed for these patients. Cancer 1997; 79:2028-35. © 1997 American Cancer Society.
Were the carolina bays oriented by gyroscopic action

All the effects of the spin of the Earth on the water in a circular eddy two miles in diameter and 100 ft deep, having a water velocity of four miles per hour near the shore, were investigated. The deflection-to-the-right, together with the centrifugal reaction out from the center of the eddy, cause the level of the water everywhere near the shore to be approximately six inches higher than it is at the center of the eddy. The change in the centrifugal reaction out from the Earth, due to the horizontal velocity of the water relative to the Earth, causes the water (in a clockwise eddy) to be less than a sixteenth of an inch higher near the north shore than near the south shore. It appears that these effects could cause-neither ellipticity nor influence the orientation of an eddy, for example, a Carolina Bay. Contrary to the assumption by Cooke [1954], an eddy does not exhibit gyroscopic action.
Multi-product splitting and Runge-Kutta-Nystrom integrators

The splitting of eh(A+B) into a single product of e h A and e hB results in symplectic integrators when A and B are classical Lie operators. However, at high orders, a single product splitting, with exponentially growing number of operators, is very difficult to derive. This work shows that, if the splitting is generalized to a sum of products, then a simple choice of the basis product reduces the problem to that of extrapolation, with analytically known coefficients and only quadratically growing number of operators. When a multi-product splitting is applied to classical Hamiltonian systems, the resulting algorithm is no longer symplectic but is of the Runge-Kutta-Nystrom (RKN) type. Multi-product splitting, in conjunction with a special force-reduction process, explains why at orders p = 4 and 6, RKN integrators only need p − 1 force evaluations.
On a method computing transient wave propagation in ionospheric regions

A consequence of an exoatmospheric nuclear burst is an electromagnetic pulse (EMP) radiated from it. In a region far enough away from the burst, where nonlinear effects can be ignored, the EMP can be represented by a large-amplitude narrow-time-width plane-wave pulse. If the ionosphere intervenes the origin and destination of the EMP, frequency dispersion can cause significant changes in the original pulse upon reception. A method of computing these dispersive effects of transient wave propagation is summarized. The method described is different from the standard transform techniques and provides physical insight into the transient wave process. The method, although exact, can be used in approximating the early-time transient response of an ionospheric region by a simple integration with only explicit knowledge of the electron density, electron collision frequency, and electron gyrofrequency required. As an illustration of the method, it is applied to a simple example and contrasted with the corresponding transform solution.
Addressing global economic inequalities in local ways in Senegal's artisanal workshops

Central Senegal was once a thriving agricultural area, but over the past century, it has struggled with repeated droughts, rising temperatures, and land mismanagement. In addition, global inequalities, including colonialism, unequal energy use, and international trade inequities, have escalated both climate change and economic insecurities worldwide. These inequalities in turn have affected local environments and economies. Throughout these long-term crises, in central Senegal, communities have relied on religious networks. Leaders of local economic development projects also work through these networks to rebuild their communities. This article focuses on the extent to which residents of two towns have used these participatory networks to address environmental and economic challenges. Their varied experiences show the importance of using a region's social foundations in communities' work toward financial viability. This article argues that local development projects that use these existing strengths as organizing principles are able to adapt to persistent challenges more successfully than those that do not. Existing networks that strengthen communities also strengthen their efforts to become sustainable.
The Origin of Solar Activity in the Tachocline

Solar active regions, produced by the emergence of tubes of strong magnetic field in the photosphere, are restricted to within 35° of the solar equator. The nature of the dynamo processes that create and renew these fields, and are therefore responsible for solar magnetic phenomena, are not well understood. We analyze the magnetorotational stability of the solar tachocline for general field geometry. This thin region of strong radial and latitudinal differential rotation, between the radiative and convective zones, is unstable at latitudes above 37°, yet is stable closer to the equator. We propose that small-scale magnetorotational turbulence prevents coherent magnetic dynamo action in the tachocline except in the vicinity of the equator, thus explaining the latitudinal restriction of active regions. Tying the magnetic dynamo to the tachocline elucidates the physical conditions and processes relevant to solar magnetism.
Model Correlation and System Health Monitoring using Frequency Domain Measurements

In this paper, algorithmic approaches to enhance model correlation and system health monitoring capability are developed in which direct frequency response function (FRF) data are utilized. The algorithmic approaches utilizes the concept of minimum rank perturbation theory. The use of direct FRFs, as opposed to measured modal parameters, is shown to be one method to address a part of the incomplete measurement problem common to model correlation and system health monitoring; namely the mismatch in the number of measured vibration modes in the measured frequency band in comparison to the number of modes included in the analytical finite element model. Key points made in the development are highlighted using numerical and experimental studies.
Lethality and centrality in protein networks

The most highly connected proteins in the cell are the most important for its survival. Proteins are traditionally identified on the basis of their individual actions as catalysts, signalling molecules, or building blocks in cells and microorganisms. But our post-genomic view is expanding the protein's role into an element in a network of protein–protein interactions as well, in which it has a contextual or cellular function within functional modules1,2. Here we provide quantitative support for this idea by demonstrating that the phenotypic consequence of a single gene deletion in the yeast Saccharomyces cerevisiae is affected to a large extent by the topological position of its protein product in the complex hierarchical web of molecular interactions.
A CONVENIENT REDUCTION OF HIGHLY FUNCTIONALIZED AROMATIC CARBOXYLIC ACIDS TO ALCOHOLS WITH BORANE-THF AND BORON TRIFLUORIDE-ETHERATE

(2002). A CONVENIENT REDUCTION OF HIGHLY FUNCTIONALIZED AROMATIC CARBOXYLIC ACIDS TO ALCOHOLS WITH BORANE-THF AND BORON TRIFLUORIDE-ETHERATE. Organic Preparations and Procedures International: Vol. 34, No. 6, pp. 665-670.
Possible New Applications of Periodic Linear Arrays

When the physical dimensions are adjusted properly, the periodic linear arrays, commonly known as Yagi-Uda arrays, may possibly be used as open waveguides or directional antennas operating at two or more widely separated frequency bands. Other applications include open low-pass or band-pass filters and open resonators.
An Alternative to inflation

Inflationary models are generally credited with explaining the large scale homogeneity, isotropy, and flatness of our universe as well as accounting for the origin of structure (i.e., the deviations from exact homogeneity) in our universe. We argue that the explanations provided by inflation for the homogeneity, isotropy, and flatness of our universe are not satisfactory, and that a proper explanation of these features will require a much deeper understanding of the initial state of our universe. On the other hand, inflationary models are spectacularly successful in providing an explanation of the deviations from homogeneity. We point out here that the fundamental mechanism responsible for providing deviations from homogeneity—namely, the evolutionary behavior of quantum modes with wavelength larger than the Hubble radius—will operate whether or not inflation itself occurs. However, if inflation did not occur, one must directly confront the issue of the initial state of modes whose wavelength was larger than the Hubble radius at the time at which they were “born.” Under some simple hypotheses concerning the “birth time” and initial state of these modes (but without any “fine tuning”), it is shown that non-inflationary fluid models in the extremely early universe would result in the same density perturbation spectrum and amplitude as inflationary models, although there would be no “slow roll” enhancement of the scalar modes.
Hot gas in the galaxy: what do we know for sure?

Resumen en: Major advances have been made in the past decade in our knowledge of the hot interstellar gas of our Milky Way galaxy. The Di use X-ray Spectrometer obt...
Design and synthesis of α-aminonitrile-functionalized novel retinoids

Abstract We have developed an expedient one-pot method for the synthesis of α-aminonitrile-functionalized new retinoids via a three-component condensation of β-cyclocitral, amine, and TMSCN (trimethyl silylcyanide) in the presence of a catalytic amount of indium(III) chloride in water. The reactions proceeded smoothly at room temperature in water to generate the corresponding retinoids in moderate to excellent yields (85–92%). In addition, the utility of this reaction was demonstrated to synthesize boron-containing retinoids.
Fantastic Voyage: Designing Self‐Powered Nanorobots

The use of swarms of nanobots to perform seemingly miraculous tasks is a common trope in the annals of science fiction.1 Although several of these remarkable feats are still very much in the realm of fiction, scientists have recently overcome many of the physical challenges associated with operating on the small scale and have generated the first generation of autonomous self-powered nanomotors and pumps. The motors can be directed by chemical and light gradients, pick up and deliver cargo, and exhibit collective behavior.
Interphalangeal joint fusion of the great toe

A retrospective analysis was done on 20 patients who underwent interphalangeal joint fusion of the great toe utilizing longitudinal cortical screw fixation. The purpose of this study was to present a series of interphalangeal joint fusion great toe done in both pediatric and adult age group using 3.5 mm cortical screws. Most of the patients had interphalangeal joint fusion along with Jones transfer and other associated procedures with a mean follow up period of 19 months. Arthrodesis was successfully achieved in all the patients and none had pain at interphalangeal joint great toe. A literature review on interphalangeal joint arthrodesis was also carried out.
Unprecedented 21st century drought risk in the American Southwest and Central Plains

In the Southwest and Central Plains of Western North America, climate change is expected to increase drought severity in the coming decades. These regions nevertheless experienced extended Medieval-era droughts that were more persistent than any historical event, providing crucial targets in the paleoclimate record for benchmarking the severity of future drought risks. We use an empirical drought reconstruction and three soil moisture metrics from 17 state-of-the-art general circulation models to show that these models project significantly drier conditions in the later half of the 21st century compared to the 20th century and earlier paleoclimatic intervals. This desiccation is consistent across most of the models and moisture balance variables, indicating a coherent and robust drying response to warming despite the diversity of models and metrics analyzed. Notably, future drought risk will likely exceed even the driest centuries of the Medieval Climate Anomaly (1100–1300 CE) in both moderate (RCP 4.5) and high (RCP 8.5) future emissions scenarios, leading to unprecedented drought conditions during the last millennium.
Computer-aided drug dosage

Major efforts have been devoted to the application of computational techniques to medical diagnosis, a difficult computational task. The amount of information necessary to perform an exhaustive diagnostic search is formidably large. The "costs" associated with making certain diagnoses or eliminating others often affect a tentative diagnosis as much as the probabilities of the conditions being considered. These "costs" are usually intuitively considered by the physician and usually are not available as numerical quantities to use in a linear programming algorithm. Lastly, diagnosis is done both rapidly and well by most physicians.
A SIMO Fiber Aided Wireless Network Architecture

The concept of a fiber aided wireless network architecture (FAWNA) is introduced in [Ray et al., Allerton Conference 2005], which allows high-speed mobile connectivity by leveraging the speed of optical networks. In this paper, we consider a single-input, multiple-output (SIMO) FAWNA, which consists of a SIMO wireless channel and an optical fiber channel, connected through wireless-optical interfaces. We propose a scheme where the received wireless signal at each interface is quantized and sent over the fiber. Though our architecture is similar to that of the classical CEO problem, our problem is different from it. We show that the capacity of our scheme approaches the capacity of the architecture, exponentially with fiber capacity. We also show that for a given fiber capacity, there is an optimal operating wireless bandwidth and an optimal number of wireless-optical interfaces. The wireless-optical interfaces of our scheme have low complexity and do not require knowledge of the transmitter code book. They are also extendable to FAWNAs with large number of transmitters and interfaces and, offer adaptability to variable rates, changing channel conditions and node positions.
COMBINATORIAL YAMABE FLOW ON SURFACES

In this paper we develop an approach to conformal geometry of piecewise flat metrics on manifolds. In particular, we formulate the combinatorial Yamabe problem for piecewise flat metrics. In the case of surfaces, we define the combinatorial Yamabe flow on the space of all piecewise flat metrics associated to a triangulated surface. We show that the flow either develops removable singularities or converges exponentially fast to a constant combinatorial curvature metric. If the singularity develops, we show that the singularity is always removable by a surgery procedure on the triangulation. We conjecture that after finitely many such surgery changes on the triangulation, the flow converges to the constant combinatorial curvature metric as time approaches infinity.
A minimization problem for the lapse and the initial-boundary value problem for Einstein's field equations

We discuss the initial-boundary value problem of general relativity. Previous considerations for a toy model problem in electrodynamics motivate the introduction of a variational principle for the lapse with several attractive properties. In particular, we show that the resulting elliptic gauge condition for the lapse together with a suitable condition for the shift and constraint-preserving boundary conditions controlling the Weyl scalar Ψ0 yields a priori estimates on the metric, connection and curvature fields. These estimates are expected to be useful for obtaining a well-posed initial-boundary value problem for metric formulations of Einstein's field equations which are commonly used in numerical relativity. To present a simple and explicit example, we consider the 3 + 1 decomposition introduced by York of the field equations on a cubic domain with two periodic directions and prove in the weak field limit that our gauge condition for the lapse, an a priori specified shift vector and our boundary conditions lead to a well-posed problem. The method discussed here is quite general and should also yield well-posed problems for different ways of writing the evolution equations, including first-order symmetric hyperbolic or mixed first-order second-order formulations. Well-posed initial-boundary value formulations for the linearization about arbitrary stationary configurations will be presented elsewhere.
Evolution of Dithiane-Based Strategies for the Construction of Architecturally Complex Natural Products

Umpolung-based strategies play a significant role in organic synthesis. Particularly important are 1,3-dithiane linchpins, which serve as convenient acyl anion equivalents. The general synthetic accessibility and impressive reactivity of 1,3-dithianes have thus led to widespread application. Since the late 1970s, dithianes have featured prominently in our program directed toward the synthesis of complex natural and unnatural products, both for effective union of advanced fragments and for multicomponent linchpin couplings. In this Account, we present the evolution of dithiane chemistry in our laboratory.
Avalanche degradation of h FE

Degradation of low current h FE as a result of avalanching the emitter-base junction of a silicon planar transistor is shown to be explinable by an increase in surface recombination velocity within the vicinity of the emitter-base metallurgical junction. This degradation mechanism manifests itself on a gate-controlled transistor by an additional peak in the plot of base current versus gate voltage. The magnitude as well as the "width" of this peak can be accounted for theoretically by assuming a given emitter-base impurity gradient and a localized increase in surface recombination velocity in and around the metallurgical junction. Experimental evidence is also presented for localized charge trapping within the oxide over the emitter-base junction as a result Of avalanching under an applied field.
Optimal Recovery from Microburst Wind Shear

Severe low-altitude wind variability represents an infrequent but significant hazard to aircraft taking off or landing. During the period from 1964 to 1985, microburst wind shear was a contributing factor in at least 26 civil aviation accidents involving nearly 500 fatalities and over 200 injuries. A microburst is a strong localized downdraft that strikes the ground, creating winds that diverge radially from the impact point. The physics of microbursts have only been recently understood in detail, and it has been found that effective recovery from inadvertent encounters may require piloting techniques that are counter-intuitive to flight crews. The goal of this work was to optimize the flight path of a twin-jet transport aircraft encountering a microburst during approach to landing. The objective was to execute an escape maneuver that maintained safe ground clearance and an adequate stall margin during the climb-out portion of the trajectory.
Where Are the Baryons

New high-resolution, large-scale cosmological hydrodynamic galaxy formation simulations of a standard cold dark matter model (with a cosmological constant) are utilized to predict the distribution of baryons at the present and at moderate redshift. It is found that the average temperature of baryons is an increasing function of time, with most of the baryons at the present time having a temperature in the range of 105-107 K. Thus not only is the universe dominated by dark matter, but more than one-half of the normal matter is yet to be detected. Detection of this warm/hot gas poses an observational challenge, which requires sensitive EUV and X-ray satellites. Signatures include a soft cosmic X-ray background, apparent warm components in hot clusters due to both intrinsic warm intracluster and intercluster gas projected onto clusters along the line of sight, absorption lines in X-ray and UV quasar spectra [e.g., O VI (1032, 1038) A lines, O VII 574 eV line], strong emission lines (e.g., O VIII 653 eV line), and low-redshift, broad, low column density Lyα absorption lines. We estimate that approximately one-fourth of the extragalactic soft X-ray background (at 0.7 keV) arises from the warm/hot gas, half of it coming from z<0.65, and three-quarters coming from z<1.00, so the source regions should be identifiable on deep optical images.
Routing in the Presence of Groups in Mobile Ad Hoc Networks

A mobile ad hoc network (MANET) is a collection of cooperative mobile nodes that communicate over a shared wireless medium, in the absence of a supporting infrastructure such as base stations. It is envisaged that MANETs will serve applications in which a group of mobile nodes collaborate to carry out a specific task, for instance, a group of mobile tourists taking a city tour. Mobile nodes participating in a group adhere to a movement pattern that maintains spatial proximity between all group members. The coordinated motion of group members and the resulting group-wise clustering of nodes, as well as the atypical traffic requirements of group mobility scenarios present a substantially different networking environment than in conventional MANETs. A routing protocol specifically tailored to exploit group mobility is, therefore, designed in this work. A service discovery-based approach to the creation of groups at the application layer and their configuration at the routing layer is first described. Next, a hierarchical design of the routing protocol that discriminates between intra- and inter-group communications is proposed. A performance evaluation of the protocol is done in network simulator-2 (ns-2).
Selective catalytic hydrogenation of an olefin moiety in the presence of a terminal alkyne function

Abstract Protection of a terminal alkyne as a (trimethyl- or tri-isopropylsilyl)alkyne permits selective catalytic hydrogenation of a mono- or disubstituted olefin moiety without reducing the alkyne function.
Barriers to e-commerce and competitive business models in developing countries: A case study

This paper integrates and extends research on e-commerce in the developing world. We use three categories of feedback systems-economic, sociopolitical and cognitive-to offer a simple model of e-commerce barriers in the developing world. We also examine characteristics of e-business models that can be successfully employed in developing countries. Then, we provide the case of an e-business model followed by a Nepal-based multiple international award winning online provider. This paper's theoretical contribution is to explain the 'hows' and 'whys' of e-commerce in developing countries and to identify clear contexts and attendant mechanism.
Effect of oxygen contamination on densification of TiB2

In order to identify the mechanisms behind the adverse effect of oxygen contamination on the densification of TiB2 ceramics, densification and grain growth behavior during pressureless sintering (1700° to 2050°C) were examined as a function of oxygen content of the powder and compared with those observed during hot-pressing (1400° to 1700°C). Marked difference in the grain size-density relations was observed between the two processing methods. Specific roles of oxygen in various kinetic processes were analyzed and the likely oxygen-bearing species were also identified.
A model of high resolution cross strip readout for photon and ion counting imaging detectors

Recent advances in the photon counting, imaging readout for microchannel plate (MCP) detectors has led to a substantial improvement in their spatial resolution. The spatial accuracy (/spl sim/7--10 /spl mu/m) of an MCP detector with a cross strip (XS) readout has been shown to be limited by the MCP pore size (<10 /spl mu/m). In this paper, we study the ultimate resolution limits of the XS readout itself. The model allows us to determine the requirements on the anode's geometry and the signal processing electronics in order to reach a particular spatial resolution. The optimal detector parameters, such as the width of the charge footprint at the anode (determined by the distance and the field between the MCP and the anode), and the gain of the detector can also be found with the help of our model. The model indicates that the optimum full-width at half-maximum of the charge footprint distribution at the anode is a factor of /spl sim/1.6 larger than the anode period. Given a noise of charge sensitive amplifiers of 350 electrons rms each we predict that the MCP gain can be as low as 2.5/spl times/10/sup 5/ for this detector to resolve /spl sim/7 /spl mu/m features. Results of our modeling also indicate that the accuracy of the position obtained for center of gravity centroiding of the charge distribution is inferior to fitting a Gaussian-like analytical function, providing the geometry of the anode is accurate enough. The model predictions are compared with the experimentally measured images and reveal the critical parameters (anode's geometric accuracy and amplifier noise), which can be improved in future detectors.
Ethical Considerations in Psychiatric Genetics

Ethical considerations in psychiatric genetics are highly complex and fluid. This review introduces the reader to the wide range of ethical considerations in this field by examining four characteristics of genetic information. First, genetic information may, to a greater or lesser extent, predict a person's future health. Second, learning about one's genotype may have profound psychosocial consequences. Third, genetic information pertains to a person's biological relatives and thus can affect family members, communities, and population groups. Finally, psychiatric genetics is a rapidly evolving field. None of these characteristics is necessarily "exceptional" or unique to genetics, but they provide a useful framework for teasing apart a complex set of ethical considerations. This article reviews conceptual and empirical data that speak to these four characteristics and then presents a set of conceptual frameworks that can be used to systematically analyze the ethics of psychiatric genetic research and clinical genotyping. Finally, directions for future study are described--including the urgent need to gather data on actual risks and benefits of psychiatric genetic research and clinical applications, so that their utility can be assessed and appropriate ethical safeguards identified.
Enantioselective syntheses of coronaridine and 18-methoxycoronaridine

Abstract Condensation of indoloazepines bearing the chiral N b -substituents: 1-( R )-naphthyl-α-ethyl, [1-( R )-[( S )-2-(diphenylphospheno)ferrocenyl]-ethyl], or 2,3-( R )-ferroceno-6,6-dimethyl-1-( S )-cyclohexyl, with 4-(1,3-dioxolan-2-yl)-hexanal, or with 4-(1,3-dioxolan-2-yl)-6-methoxyhexanal, gave diastereoselectively, through a secodine-type intramolecular Diels–Alder reaction, tetracyclic intermediates that could be carried to (−)-coronaridine or to the important anti-addictive (−)-18-methoxycoronaridine. The 2,3-( R )-ferroceno-6,6-dimethyl-1-( S )-cyclohexyl chiral auxiliary was most effective, providing >99% ee of a tetracyclic intermediate after removal of the chiral auxiliary group.
Feedback and Revising in an Intelligent Tutoring System for Writing Strategies

This study investigates students’ essay revising in the context of an intelligent tutoring system called Writing Pal (W-Pal), which combines strategy instruction, game-based practice, essay writing practice, and automated formative feedback. We examine how high school students use W-Pal feedback to revise essays in two different contexts: a typical approach that emphasizes intensive writing practice, and an alternative approach that offers less writing practice with more direct strategy instruction. Results indicate that students who wrote fewer essays, but received W-Pal strategy instruction, were more likely to make substantive revisions that implemented specific recommendations conveyed by the automated feedback. Additional analyses consider the role of motivation and perceived learning on students’ revising behaviors.
Property-Preserving Data Reconstruction

We initiate a new line of investigation into online property-preserving data reconstruction. Consider a dataset which is assumed to satisfy various (known) structural properties; e.g., it may consist of sorted numbers, or points on a manifold, or vectors in a polyhedral cone, or codewords from an error-correcting code. Because of noise and errors, however, an (unknown) fraction of the data is deemed unsound, i.e., in violation with the expected structural properties. Can one still query into the dataset in an online fashion and be provided data that is always sound? In other words, can one design a filter which, when given a query to any item I in the dataset, returns a sound item J that, although not necessarily in the dataset, differs from I as infrequently as possible. No preprocessing should be allowed and queries should be answered online. We consider the case of a monotone function. Specifically, the dataset encodes a function f:{1,…,n} ↦ R that is at (unknown) distance e from monotone, meaning that f can—and must—be modified at e n places to become monotone. Our main result is a randomized filter that can answer any query in O(log 2 nlog log n) time while modifying the function f at only O(e n) places. The amortized time over n function evaluations is O(log n). The filter works as stated with probability arbitrarily close to 1. We provide an alternative filter with O(log n) worst case query time and O(e nlog n) function modifications. For reconstructing d-dimensional monotone functions of the form f:{1,…,n} d ↦ R, we present a filter that takes (2 O(d)(log n)4d−2log log n) time per query and modifies at most O(e n d ) function values (for constant d).
Zeros of Rydberg–Rydberg Föster interactions

Rydberg states of atoms are of great current interest for quantum manipulation of mesoscopic samples of atoms. Long-range Rydberg–Rydberg interactions can inhibit multiple excitations of atoms under the appropriate conditions. These interactions are strongest when resonant collisional processes give rise to long-range C3/R3 interactions. We show in this paper that even under resonant conditions C3 often vanishes so that care is required to realize full dipole blockade in micron-sized atom samples.
Economics, food choices, and nutrition

Abstract Our goal in this paper is to examine the role and influence of economic factors, defined rather broadly, on consumer food choices, and, hence, nutritional outcomes. We attempt to do this in a non-technical fashion. We examine the role of prices, especially as they relate to the affordability of food in the United States and as a policy lever. Income is analyzed as a driving force behind changes in eating habits, in particular increasing the demand for convenience. The role of time constraints as well as time preference are examined as links to healthy eating habits and as forces behind current trends in eating patterns. Information and knowledge are given prominent play as counter balances to economic forces driving eating habits. We conclude with and examination into maternal nutrition knowledge and children's dietary quality.
ON MAINTAINING THE WIDTH AND DIAMETER OF A PLANAR POINT-SET ONLINE

Efficient online algorithms are presented for maintaining the (almost-exact) width and diameter of a dynamic planar point-set, S. Let n be the number of points currently in S, let W and D denote the width and diameter of S, respectively, and let α>1 and β≥1 be positive, integer-valued parameters. The algorithm for the width problem uses O(αn) space, supports updates in O(α log2 n) time, and reports in O(α log2 n) time an approximation, Ŵ, to the width such that . The algorithm for the diameter problem uses O(βn) space, supports updates in O(β log n) time, and reports in O(β) time an approximation, , to the diameter such that . Thus, for instance, even for α as small as 11, Ŵ/W≤1.01, and for β as small as 9, . All bounds stated are worst-case. Both algorithms, but especially the one for the diameter problem, use well-understood data structures and should be simple to implement. The diameter result yields a fast implementation of the greedy heuristic for maximum-weight Euclidean matching and an efficient online algorithm to maintain approximate convex hulls in the plane.
2-D depth migration in transversely isotropic media using explicit operators

The author presents and analyzes three approaches to calculating explicit two-dimensional (2D) depth-extrapolation filters for all propagation modes (P, SV, and SH) in transversely isotropic media with vertical and tilted axis of symmetry. These extrapolation filters are used to do 2D poststack depth migration, and also, just as for isotropic media, these 2D filters are used in the McClellan transformation to do poststack 3D depth migration. Furthermore, the same explicit filters can also be used to do depth-extrapolation of prestack data. The explicit filters are derived by generalizations of three different approaches: the modified Taylor series, least-squares, and minimax methods initially developed for isotropic media. The examples here show that the least-squares and minimax methods produce filters with accurate extrapolation (measured in the ability to position steep reflectors) for a wider range of propagation angles than that obtained using the modified Taylor series method. However, for low propagation angles, the modified Taylor series method has smaller amplitude and phase errors than those produced by the least-squares and minimax methods. These results suggest that to get accurate amplitude estimation, modified Taylor series filters would be somewhat preferred in areas with low dips. In areas with larger dips, the least-squares and minimaxmore » methods would give a distinctly better delineation of the subsurface structures.« less
Do accountability and voucher threats improve low-performing schools?

Abstract We study the effects of the threat of vouchers and stigma in Florida on the performance of “low-performing” schools. Estimates of the change in raw test scores from the first year of the reform are consistent with the early results which claimed large improvements associated with the threat of vouchers. However, we also find that much of this estimated effect may be due to other factors. The relative gains in reading are largely explained by changing student characteristics and the gains in math—though larger—appear limited to the high-stakes grade. We also find some evidence that these improvements were due more to the stigma of receiving the low grade rather than the threat of vouchers.