cssi/SciSciGPT-SciSciNet huggingface dataset:
A Preoperative Nomogram for Disease Recurrence Following Radical Prostatectomy for Prostate Cancer

Background: Few published studies have combined clinical prognostic factors into risk profiles that can be used to predict the likelihood of recurrence or metastatic progression in patients following treatment of prostate cancer. We developed a nomogram that allows prediction of disease recurrence through use of preoperative clinical factors for patients with clinically localized prostate cancer who are candidates for treatment with a radical prostatectomy. Methods: By use of Cox proportional hazards regression analysis, we modeled the clinical data and disease follow-up for 983 men with clinically localized prostate cancer whom we intended to treat with a radical prostatectomy. Clinical data included pretreatment serum prostate-specific antigen levels, biopsy Gleason scores, and clinical stage. Treatment failure was recorded when there was clinical evidence of disease recurrence, a rising serum prostate-specific antigen level (two measurements of 0.4 ng/mL or greater and rising), or initiation of adjuvant therapy. Validation was performed on a separate sample of 168 men, also from our institution. Results: Treatment failure (i.e., cancer recurrence) was noted in 196 of the 983 men, and the patients without failure had a median follow-up of 30 months (range, 1-146 months). The 5-year probability of freedom from failure for the cohort was 73% (95% confidence interval = 69%-76%). The predictions from the nomogram appeared accurate and discriminating, with a validation sample area under the receiver operating characteristic curve (i.e., comparison of the predicted probability with the actual outcome) of 0.79. Conclusions: A nomogram has been developed that can be used to predict the 5-year probability of treatment failure among men with clinically localized prostate cancer treated with radical prostatectomy.
Optimal Demand Bidding for Time-Shiftable Loads

Time-shiftable loads have recently received an increasing attention due to their role in creating load flexibility and enhancing demand response and peak-load shaving programs. In this paper, we seek to answer the following question: how can a time-shiftable load, that itself may comprise of several smaller time-shiftable subloads, submit its demand bids to the day-ahead and real-time markets so as to minimize its energy procurement cost? Answering this question is challenging because of the inter-temporal dependencies in choosing the demand bids for time-shiftable loads and due to the coupling between demand bid selection and time-shiftable load scheduling problems. Nevertheless, we answer the above question for different practical bidding scenarios and based on different statistical characteristics of practical market prices. In all cases, closed-form solutions are obtained for the optimal choices of the price and energy bids. The bidding performance is then evaluated in details by examining several case studies and analyzing actual market price data.
Integration of geometric modeling and advanced finite element preprocessing

Abstract The structure to a geometry-based finite element preprocessing system is presented. The key features of the system are the use of geometric operators to support all geometric calculations required for analysis model generation, and the use of a hierarchic boundary-based data structure for the major data sets within the system. The approach presented can support the finite element modeling (FEM) procedures used today as well as the fully automated procedures under development.
Novel tricyclic heterocycles (benzopyrrocolines) arising via carbanion attack on a nitrile function

A new reaction of 2-n-alkanoyl-1,2-dihydroisoquinaldonitriles 1 (isoquinoline Reissert compounds) has been discovered. As previously reported reaction of the conjugate bases of Reissert compounds with alkyl halides yields the corresponding 1-alkyl derivatives 2. However, compounds 2, R = n-alkyl, with only a catalytic amount of bases form the enolate ion, which attacks the neighboring nitrile functionality to produce directly in the same reaction vessel excellent yields of benzopyrrocoline derivatives 5-10. The nmr spectrum reveals a solvent dependent tautomeric equilibrium between ketoeneamine (a) and ketoimine (b) forms. Unlike compounds 2 the double bonds of the pyridine ring of compounds 7 and 8 were readily reduced with hydrogen. Thus, n-alkanoyl Reissert compounds afford a convenient route to the corresponding benzopyrroco-lines.
Triplex-catalyzed diels-alder and [2+2] cycloaddition reactions of enol ethers and ketene acetals

Abstract Irradiation of benzene solutions containing a cyanoarene sensitizer, 1,3-cyclohexadiene, and a trimethylsilyl enol ether or ketene acetal leads to intermolecular [4+2] and [2+2] cycloaddition products.
The Spherical Accretion Shock Instability in the Linear Regime

We use time-dependent, axisymmetric, hydrodynamic simulations to study the linear stability of the stalled, spherical accretion shock that arises in the postbounce phase of core-collapse supernovae. We show that this accretion shock is stable to radial modes, with decay rates and oscillation frequencies in close agreement with the linear stability analysis of Houck and Chevalier. For nonspherical perturbations we find that the l = 1 mode is always unstable for parameters appropriate to core-collapse supernovae. We also find that the l = 2 mode is unstable, but typically has a growth rate smaller than that for l = 1. Furthermore, the l = 1 mode is the only mode found to transition into a nonlinear stage in our simulations. This result provides a possible explanation for the dominance of an l = 1 "sloshing" mode seen in many two-dimensional simulations of core-collapse supernovae.
PERMUTATION COMPLEXITY AND THE LETTER DOUBLING MAP

Given a countable set X (usually taken to be ℕ or ℤ), an infinite permutation π of X is a linear ordering ≺π of X, introduced in [6]. This paper investigates the combinatorial complexity of infinite permutations on ℕ associated with the image of uniformly recurrent aperiodic binary words under the letter doubling map. An upper bound for the complexity is found for general words, and a formula for the complexity is established for the Sturmian words and the Thue-Morse word.
Synthesis and Anion Exchange of Tunnel Structure Akaganeite

Akaganeite (β-FeOOH) has been prepared by the hydrolysis of FeCl3 solutions. The effects of microwave heating, pH of the solution, and addition of manganese with different valence states have been ...
Linear Rocket Engine Design-Fabrication-Testing

A new rocket engine concept that is presently being evaluated offers significant performance, cost, and configurational advantages. The Linear Rocket Engine System, (LRES) combines the unique performance and operational advantages of the aerospike nozzle with the configuration versatility of low cost modular combustors, which results in a high-performance rocket engine package designed specifically for use in advanced configuration vehicles. This paper describes the design, fabrication, and testing of the LRES concept to evaluate its potential for vehicle integration. The program was conducted under the sponsorship of NASA's Marshall Space Flight Center.
Grignard reactions of 4-substituted-2-keto-1,3-dioxanes: highly diastereoselective additions controlled by a remote alkyl group.

The reactions of Grignard reagents with a representative series of simple cis-2-keto-4-substituted-1,3-dioxanes have been investigated. The stereochemical outcome of these highly diastereoselective additions (dr > 90:10) is consonant with Cram's chelate model on the assumption that RMgX coordinates preferentially with the ring oxygen remote from the C(4) substituent.
Strong spin relaxation length dependence on electric field gradients

We discuss the influence of electrical effects on spin transport, and in particular the propagation and relaxation of spin polarized electrons in the presence of inhomogeneous electric fields. We show that the spin relaxation length strongly depends on electric field gradients, and that significant suppression of electron spin polarization can occur as a result thereof. A discussion in terms of a drift-diffusion picture, and selfconsistent numerical calculations based on a Boltzmann-Poisson approach shows that the spin relaxation length in fact can be of the order of the charge screening length. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Array sensing using optical methods for detection of chemical and biological hazards

By mimicking the mammalian senses of taste and smell, artificial arrays of cross-reactive receptors have found use in a variety of sensing applications. Pattern recognition algorithms allow these arrays to be used for discriminating analytes and even for predicting the identity of unknown analytes. Furthermore, in selecting a signaling method for these assays, the choice of optical detection is particularly desirable due to its high sensitivity and the associated convenient instrumentation. This tutorial review provides a brief introduction to array sensing using optical detection and chemometrics. While differential sensing approaches have been used for a number of applications, this review focuses on progress towards the detection of chemical and biological hazards.
High-speed photoluminescence mapping of III-V epitaxial layers for light-emitting diodes

Three examples are presented which demonstrate how photoluminescence wafer mapping is routinely used in the development and manufacturing of III-V optoelectronic materials and devices. Statistical data from the full-wafer PL scans of epitaxial layers is correlated with the device performance of fabricated light-emitting diodes, and can be used to predict the brightness, uniformity and yield of these devices.
UCLA space-time area law model: A persuasive foundation for hadronization

From the studies of rates and distributions of heavy quark (c, b) mesons we have developed additional evidence that hadron formation, at least in the simplest environment of e+e- collisions, is dominantly controlled by a space-time area law (“STAL”), an approach suggested by both non-perturbative QCD and relativistic string models. From the dynamics of heavy quarks whose classical space-time world-lines deviate significantly from the light-cone, we report the exact calculation of the relevant space-time area and the derivation of a Lorentz invariant variable, zeff, which reduces to the light-cone momentum fraction z for low mass quarks. Using zeff in the exponent of our fragmentation function in place of z, we find persuasive agreement with L=0, 1 charmed and bottom meson data as well as for u, d, s L=0 states. Presuming STAL to be a valid first-order description for all these meson data, we find the scale of other possible second-order effects to be limited to ∼20% or less of the observed rates. The model favors a b-quark mass of ∼4.5 GeV.
The synthesis and structure of Ca2InN, a novel ternary indium nitride

Abstract Dark red metallic-looking needles of Ca 2 InN were synthesized in sealed niobium tubes from the elements in molten sodium with sodium azide as the nitrogen source. It crystallizes in the orthorhombic space group Cmcm (No.63), cell parameters a =3.532(3) A, b =20.204(16) A, c =4.969(4) A and is isotypic to Ca 2 AuN. It is characterized by one dimensional zig-zag chains of indium and planes of Ca 6 N edge sharing octahedra. Extended Huckel calculations show the intra-chain bonding to be much more significant than the inter-chain interactions. Significant mixing of Ca and In orbitals leads to important interactions between the chains and the calcium nitride layers.
Balancing the risks: Choosing climate alternatives

Very aggressive reductions in greenhouse gas emissions are needed over the next ten years to avoid a planet on fire. Current sub-national, national and international policy assumes that carbon sequestration, biofuels, nuclear power, ocean fertilization, atmospheric aerosols, and other such technologies, which heretofore have been considered too novel or too dangerous to use, will have to be deployed at large scale, globally. Moving forward with promising technologies that might preserve us from the consequences of global warming will be difficult because they also pose potential hazards, promise uncertain benefits, and in some cases are already burdened with restrictive legislation and poor public image. The lack of a rational process of risk assessment and public decision making is likely to lead to a poor long-term outcome. Moreover, the standard administrative and political processes used to assess such risks can take years, time that we do not have. Principled and practical policymaking demand citizens participate in the decision to develop and use these novel technologies. Environmental assessment, horizon scanning, and new research on human and organizational factors suggest techniques to improve technology development decisions.
Online point location in planar arrangements and its applications

Recently, Har-Peled [17] presented a new randomized technique for online construction of the zone of a curve in a planar arrangement of arcs. In this paper: we present several applications of this technique, which yield improved solutions to a variety of problems. These applications include: (i) an efficient mechanism for performing online point location queries in an arrangement of arcs; (ii) an efficient algorithm for computing an approximation to the minimum-weight Steiner-tree of a set of points, where the weight is the number of intersections between the tree edges and a given collection of arcs; (iii) a subquadratic algorithm for cutting a set of pseudo-parabolas into pseudo-segments; (iv) an algorithm for cutting a set of line segments (`rods') in 3-space so as to eliminate all cycles in the vertical depth order; and (v) a near-optimal algorithm for reporting all bichromatic intersections between a set R of red arcs and a set B of blue arcs, where the unions of the arcs in each set are both connected.
Dispatcher-assisted cardiopulmonary resuscitation: risks for patients not in cardiac arrest.

Background— Dispatcher-assisted cardiopulmonary resuscitation (CPR) instructions can increase bystander CPR and thereby increase the rate of survival from cardiac arrest. The risk of bystander CPR for patients not in arrest is uncertain and has implications for how assertive dispatch is in instructing CPR. We determined the frequency of dispatcher-assisted CPR for patients not in arrest and the frequency and severity of injury related to chest compressions. Methods and Results— The investigation was a prospective cohort study of adult patients not in cardiac arrest for whom dispatchers provided CPR instructions in King County, Washington, between June 1, 2004, and January 31, 2007. The study focused on those who received chest compressions. Information was collected through review of the audio and written dispatch report, written emergency medical services report, hospital record, and telephone survey. Of the 1700 patients for whom dispatcher CPR instructions were initiated, 55% (938 of 1700) were in arre...
Dynamics and Stellar Content of the Giant Southern Stream in M31. II. Interpretation

We examine the nature of the progenitor of the giant stellar stream in M31 using as constraints new radial velocity measurements of stream red giant stars (presented in the companion paper by Guhathakurta and coworkers) along with other M31 data sets available in the literature. We find that the observations are best fitted by orbits that are highly eccentric and close to edge-on, with apocenter to pericenter ratios on the order of 25-30 and with apocenters at or only slightly beyond the southern edge of the current data. Among these orbits we are able to find a few that plausibly connect the stream with the northern spur or with the low surface brightness feature of high metallicity similar to that of the stream (originally reported by Ferguson and coworkers) to the east of M31's center. In the latter case, if the connection is real, then the eastern debris should lie well in front of M31, near the apocenter of the orbit. Both the width of the debris and velocity dispersion measurements imply a rough lower limit on the mass of the progenitor of 108 M⊙. We use this limit and our orbits to discuss which of M31's satellites could be plausibly associated with the stream. In addition, we predict that the width of the stream should increase beyond the southern edge of the current data around the apocenter of the orbit and that the line-of-sight velocity dispersion should exhibit significant variations along the stream.
Adaptive Sum Power Iterative Waterfilling for MIMO Cognitive Radio Channels

In this paper, the sum capacity of the Gaussian multiple input multiple output (MIMO) cognitive radio channel (MCC) is expressed as a convex problem with finite number of linear constraints, allowing for polynomial time interior point techniques to find the solution. In addition, a specialized class of sum power iterative waterfilling algorithms is determined that exploits the inherent structure of the sum capacity problem. These algorithms not only determine the maximizing sum capacity value, but also the transmit policies that achieve this optimum. The paper concludes by providing numerical results which demonstrate that the algorithm takes very few iterations to converge to the optimum.
Particle identification methods in high-energy physics

Abstract This paper deals with two major particle identification methods: d E /d x and Cherenkov detection. In the first method, we systematically compare existing d E /d x data with various predictions available in the literature, such as the Particle Data Group recommendation, and judge the overall consistency. To my knowledge, such comparison was not done yet in a published form for the gaseous detectors used in high-energy physics. As for the second method, there are two major Cherenkov light detection techniques: the threshold and the Ring imaging methods. We discuss the recent trend in these techniques.
Supersonic Flow over an Axisymmetric Backward-Facing Step

Large eddy numerical simulations of supersonic flows over an axisymmetric backward-facing step have been completed using a recently developed axisymmetric version of the finite element method-flux corrected transport algorithm, FEM-FCT. The code is based on the mixing layer and recompression premises of the Chapman-Korst model. It solves the time-accurate Euler equations utilizing 1) adaptive unstructured gridding to resolve flow feature details and 2) a conservative nonlinear scheme to capture features in the compressible flowfield. This approach may be employed since the location of the separation point is fixed at the sharp corner. The simulation allows the large-scale structures present in the mixing layer to interact dynamically with the recompression region. Comparisons have been made with available experimental data for a range of Mach numbers and step height to step radius ratios for which boundary-layer effects are not pronounced. In general, good agreement between predictions and measurements was found for 1) the time-averaged surface pressure distributions along the backstep and the reattachment wall, 2) the flowfield structure in general, and 3) the downstream reattachment lengths. Effects of axisymmetry were noted in flowfield characteristics such as increased base pressure, curvature of expansion fans, stronger recompression shocks, and higher Mach number levels in the subsonic recirculating region.
Trichloromethyl carbonate as a practical phosgene source: application to the synthesis of α-chloro chloroformates

Abstract Trichloromethyl carbonate 1 is used as a phosgene source in the preparation of α-chloro chloroformates. This stable, crystalline reagent smoothly delivers products 3 in good yield under mild conditions.
Double stream cyclotron maser

Abstract The double stream cyclotron maser is a novel source of millimeter wavelength radiation in which two copropagating electron beams are caused to gyrate in a uniform axial magnetic field. The interaction of the slow cyclotron space charge wave on one beam with the fast cyclotron space charge wave on the other beam leads to high frequency bunching. The desired operating frequency is proportional to the electron cyclotron frequency (or a harmonic thereof) and inversely proportional to the difference in beam velocities, and can be achieved at low beam energies and axial magnetic fields. The linear instability growth rate is calculated from the fully relativistic Vlasov equation for the case of cold electron beams.
Vibrational spectra of cyclobutanecarbonyl chloride and bromide and their α-deuterated compounds

Abstract The IR spectra of cyclobutanecarbonyl chloride and bromide and their α-deuterated compounds have been recorded in the vapor, liquid and crystal states. The Raman spectra have also been measured in the liquid state. Comparison of the spectra in the liquid phase with those in the crystal phase reveals that these acyl halides exist in a conformational equilibrium in the liquid state. Tentative vibrational assignments are proposed on the basis of the isotope effect and previous published results for other simple cyclobutane compounds.
Dynamic reconfiguration and routing algorithms for IP-over-WDM networks with stochastic traffic

We develop algorithms for joint IP-layer routing and WDM logical topology reconfiguration in IP-over-WDM networks experiencing stochastic traffic. At the wavelength division multiplexing (WDM) layer, we associate a nonnegligible overhead with WDM reconfiguration, during which time tuned transceivers cannot service backlogged data. The Internet Protocol (IP) layer is modeled as a queueing system. We demonstrate that the proposed algorithms achieve asymptotic throughput optimality by using frame-based maximum weight scheduling decisions. We study both fixed and variable frame durations. In addition to dynamically triggering WDM reconfiguration, our algorithms specify precisely how to route packets over the IP layer during the phases in which the WDM layer remains fixed. We demonstrate that optical-layer constraints do not affect the results, and provide an analysis of the specific case of WDM networks with multiple ports per node. In order to gauge the delay properties of our algorithms, we conduct a simulation study and demonstrate an important tradeoff between WDM reconfiguration and IP-layer routing. We find that multihop routing is extremely beneficial at low-throughput levels, while single-hop routing achieves improved delay at high-throughput levels. For a simple access network, we demonstrate through simulation the benefit of employing multihop IP-layer routes.
Early career PhD salaries: the industry premium and interdisciplinary debate

Despite the fact that earning the PhD in any given field requires clear investments, the individual returns for such commitments have not been closely studied. This article utilizes data from the Survey of Earned Doctorates to address three questions concerning the salaries earned by recent PhD recipients. We find that (1) industry salaries are significantly higher than other employment sectors and (2) salaries for people who complete interdisciplinary dissertations appear to show – with some noted exceptions – neither a premium nor a penalty when interacted with employment sector and discipline.
Advertising's effect on the market demand elasticity: A note

Using a simple market model and Frisch's duality relation, this report develops propositions about the relationship between advertising and the market demand elasticity that may prove useful in empirical research. In particular, we find that a parallel shift in a linear demand function always alters the market demand elasticity unless supply is unitary elastic. However, the elasticity change in most cases will be negligible. We also find that curve rotation does not imply that the demand elasticity has changed, and vice versa. Lastly, if the price level affects advertising's ability to shift the market demand curve, it must also be true that advertising affects the demand elasticity. The converse is also true, i.e., if advertising affects the demand elasticity, the price level must affect advertising's ability to shift the demand curve. [JEL citations: Q130, Q170, Q180.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 181–188, 2004.
Cross-metathesis-based approaches to heteroaromatics: combining catalysts for furan formation.

Ring-closing olefin metathesis (RCM) is an effective method for the formation of cyclic alkenes (1). Recently, the aromatization of RCM products has emerged as a topic of intensive investigation (2). In this context, a variety of regiocontrolled protocols have been developed for the synthesis of diverse heteroaromatic compounds, such as pyridines, pyridazines, pyrroles, quinolines, and furans (2). In all reported approaches, a key strategic consideration relates to the requirement of intermolecular fragment union in advance of the key RCM event. Strategies based on the use of intermolecular alkene metathesis, termed cross-metathesis, would potentially streamline access to aromatic structures by uniting the key steps of fragment coupling and alkene formation. However, the use of cross-metathesis in the synthesis of aromatic heterocycles is prohibited by the fact that trans-alkene products predominate (3, 4), which are unsuitable for cycloaromatization. A report by Donohoe and Bower (3) in this issue of …
Pose estimation from video sequences based on Sylvester's equation

In this paper, we introduce a method to jointly track the object motion and estimate pose within the framework of particle filtering. We focus on direct estimation of the 3D pose from a 2D image sequence. Scale-Invariant Feature Transform (SIFT) is used to extract feature points in the images. We show that pose estimation from the corresponding feature points can be formed as a solution to Sylvester's equation. We rely on a solution to Sylvester's equation based on the Kronecker product method to solve the equation and determine the pose state. We demonstrate that the classical Singular Value Decomposition (SVD) approach to pose estimation provides a solution to Sylvester's equation in 3D-3D pose estimation. The proposed approach to the solution of Sylvester's equation is therefore equivalent to the classical SVD method for 3D-3D pose estimation, yet it can also be used for pose estimation from 2D image sequences. Finally, we rely on computer simulation experiments to demonstrate the performance of our algorithm on video sequences.
Capacitive Spring Softening in Single-Walled Carbon Nanotube Nanoelectromechanical Resonators

We report the capacitive spring softening effect observed in single-walled carbon nanotube (SWNT) nanoelectromechanical (NEM) resonators. The nanotube resonators adopt a dual-gate configuration with both bottom-gate and end-gate capable of tuning the resonance frequency through capacitive coupling. Interestingly, downward resonance frequency shifting is observed with increasing end-gate voltage, which can be attributed to the capacitive softening of the spring constant. Furthermore, in-plane vibrational modes exhibit a much stronger spring softening effect than out-of-plan modes. Our dual-gate design should enable the differentiation between these two types of vibrational modes and open up the new possibility for nonlinear operation of nanotube resonators.
Bidirectional enantioselective effects of the GABAB receptor agonist baclofen in two mouse models of excessive ethanol consumption

Abstract The GABA B receptor agonist baclofen has been studied extensively in preclinical models of alcohol-use disorders, yet results on its efficacy have been uncertain. Racemic baclofen, which is used clinically, can be broken down into separate enantiomers of the drug. Baclofen has been shown to produce enantioselective effects in behavioral assays, including those modeling reflexive and sexual behavior. The current studies sought to characterize the enantioselective effects of baclofen in two separate models of ethanol consumption. The first was a Drinking-in-the-Dark procedure that provides "binge-like" ethanol access to mice by restricting access to a 2-h period, 3 h into the dark cycle. The second was a two-bottle choice procedure that utilized selectively bred High Alcohol Preferring 1 (HAP1) mice to model chronic ethanol access. HAP1 mice are selectively bred to consume pharmacologically relevant amounts of ethanol in a 24-h two-bottle choice paradigm. The results showed that baclofen yields enantioselective effects on ethanol intake in both models, and that these effects are bidirectional. Total ethanol intake was decreased by R(+)-baclofen, while total intake was increased by S(−)-baclofen in the binge-like and chronic drinking models. Whereas overall binge-like saccharin intake was significantly reduced by R(+)-baclofen, chronic intake was not significantly altered. S(−)-baclofen did not significantly alter saccharin intake. Neither enantiomer significantly affected locomotion during binge-like reinforcer consumption. Collectively, these results demonstrate that baclofen produces enantioselective effects on ethanol consumption. More importantly, the modulation of consumption is bidirectional. The opposing enantioselective effects may explain some of the variance seen in published baclofen literature.
Interplanetary field and plasma during initial phase of geomagnetic storms.

Twenty-three geomagnetic storm events during 1966 to 1970 were studied by using simultaneous interplanetary magnetic field and plasma parameters. Explorer 33 and 35 field and plasma data were analyzed on large-scale (hourly) and small-scale (3 min.) during the time interval coincident with the initial phase of the geomagnetic storms. The solar-ecliptic Bz component turns southward at the end of the initial phase, thus triggering the main phase decrease in Dst geomagnetic field. The By component also shows large fluctuations along with Bz. When there are no clear changes in the Bz component, the By shows abrupt changes at the main phase onset. On the small-scale, behavior of the magnetic field and electric field were studied in detail for the three events; it is found that the field fluctuations in By, Bz and Ey and Ez are present in the initial phase. In the large-scale, the behavior field remains quiet because the small-scale variations are averaged out. It appears that large as well as small time scale fluctuations in the interplanetary field and plasma help to alter the internal electromagnetic state of the magnetosphere so that a ring current could causing a geomagnetic storm decrease.
Electron Acceleration and the Production of Nonthermal Electron Distributions in Accretion Disk Coronae

We consider electron acceleration by obliquely propagating fast-mode waves in magnetically dominated accretion disk coronae. For low coronal plasma densities, acceleration can exceed Coulomb drag at lower energies and energize electrons out of the thermal background, which results in a nonthermal tail. The extent of this tail is determined by the balance between acceleration and radiative cooling via inverse Compton scattering and synchrotron emission and usually goes out to tens of MeV. This will have direct applications for explaining the gamma rays from several Galactic black hole candidates, such as Cyg X-1 and GRO J0422, which show 0.5-5 MeV emissions in excess of what most thermal models predict. Detailed time evolutions of the particle distributions and wave spectra are also presented.
Hydrogen-Bond-Promoted Hetero-Diels−Alder Reactions of Unactivated Ketones

We report the first examples of hydrogen-bond-promoted acceleration of hetero-Diels-Alder reactions and the use of such catalysis for the hetero-Diels-Alder reactions of simple, unactivated ketones. Several spiro-fused dihydropyans were synthesized in good yields using this procedure. This activation protocol represents an attractive and operationally simple alternative to conventional, Lewis acid catalysis.
Instrument Front-Ends at Fermilab During Run II

The optimization of an accelerator relies on the ability to monitor the behavior of the beam in an intelligent and timely fashion. The use of processor-driven front-ends allowed for the deployment of smart systems in the field for improved data collection and analysis during Run II. This paper describes the implementation of the two main systems used: National Instruments LabVIEW running on PCs, and WindRiver's VxWorks real-time operating system running in a VME crate processor.
Synthesis of 1,2-dioxanes, 1,2,4-trioxanes, and 1,2,4-trioxepanes via cyclizations of unsaturated hydroperoxyacetals

Abstract Unsaturated hydroperoxyacetals and -ketals undergo electrophilic cyclization to afford dioxanes, trioxanes or trioxepanes. Stereoselectivity is low tor trioxepanes, moderate for dioxanes, and high for trioxanes. The hydroperoxide starting materials are readily prepared through selective ozonolysis of an enol ether in the presence of an internal or external alkene.
The Effects of Farm Commodity and Retail Food Policies on Obesity and Economic Welfare in the United States

Many commentators claim that farm subsidies have contributed significantly to the “obesity epidemic” by making fattening foods relatively cheap and abundant and, symmetrically, that taxing “unhealthy” commodities or subsidizing “healthy” commodities would contribute to reducing obesity rates. In this article we use an equilibrium displacement model to estimate and compare the economic welfare effects from a range of hypothetical farm commodity and retail food policies as alternative mechanisms for encouraging consumption of healthy food or discouraging consumption of unhealthy food, or both. We find that, compared with retail taxes on fat, sugar, or all food, or subsidies on fruits and vegetables at the farm or retail levels, a tax on calories would be the most efficient obesity policy. A tax on calories would have the lowest deadweight loss per pound of fat reduction in average adult weight, and would yield a net social gain once the impact on public health care expenditures is considered.
The international pulsar timing array: a galactic scale gravitational wave observatory

The phenomenal rotational stability of millisecond pulsars allows them to be used as precise celestial clocks. An array of these pulsars can be exploited to search for correlated perturbations in their pulse times of arrival due to gravitational waves. Here, I describe the observations and analysis necessary to accomplish this goal and present an overview of the efforts of the worldwide pulsar timing community. Due to a growing number of millisecond pulsar discoveries, improved instrumentation, and growing timespans of observation, the sensitivity of our pulsar timing array experiments is expected to dramatically increase over the next several years, leading to either a gravitational wave detection or very stringent constraints on low-frequency gravitational wave source populations before the end of the decade.
Side-Force Amplification on an Aerodynamically Thrust-Vectored Aerospike Nozzle

Results from computational and coldow experiments on uidic thrust vectoring of a small-scale aerospike thruster are presented. Thrust vectoring is produced by injection of a secondary uid into the primary ow eld normal to the nozzle axis. The experimental aerospike nozzle was truncated at 57% of its full theoretical length. For these tests, carbon dioxide is the working uid. Injection points near the end of the truncated spike produced the highest force ampli cation factors. Explanations are given for this phenomenon. For secondary injection near the end of the aerospike, side force ampli cation factors up to 1.4 and side force speci c impulses up to 55 s were demonstrated. By comparison, the main ow speci c impulse averaged approximately 38s. Secondary side-injection pulses were observed to crisply reproduce side forces with a high degree of delity. Side force levels approach 2.7% of the total thrust level at maximum e ciency. Higher side forces of 4.7% axial thrust were also achieved at reduced e ciency. The side force ampli cation factors were independent of operating nozzle pressure ratio for the range of chamber pressures evaluated in this test series.
An Electrochemical and X‐Ray Photoelectron Spectroscopy Study of the Passive State of Chromium

The passive state of chromium has been examined in 1M H 2 SO 4 by a variety of electrochemical techniques and x-ray photoelectron spectroscopy. The potentiodynamic behavior of the passive electrode may be described by high-field film growth kinetics. The passivating oxide film is 5-25 A thick and consists of chromic ions bridged together by a network of water, hydroxide, and oxide ligands. The film thickness is a linear function of potential while the electrode capacitance is inversely proportional to the applied potential
Acoustic wave propagation in heterogeneous structures including experimental validation

A finite element model was developed to solve for the acoustic pressure and energy fields in a heterogeneous suppressor. The derivations from the governing equations assumed that the material properties could vary with position resulting in a heterogeneous variable property two-dimensional wave equation. This eliminated the necessity of finding the boundary conditions between different materials. For a two media region consisting of part air and part bulk absorber, a model was used to describe the bulk absorber properties in two directions. Complex metallic structures inside the air duct are simulated by simply changing element properties from air to the structural material in a pattern to describe the desired shapes. To verify the numerical theory, experiments were conducted without flow in a rectangular duct with a single folded cavity mounted above the duct and absorbing material mounted inside a cavity. Changes in a nearly plane wave sound field were measured on the wall opposite the absorbing cavity. Fairly good agreement was found in the standing wave pattern upstream of the absorber and in the decay of pressure level opposite the absorber, as a function of distance along the duct. The finite element model provides a convenient method for evaluating the acoustic properties of bulk absorbers.
Twice-Running-Speed Response Due to Elliptical Bearing Clearances

Yamamoto [1] examined a vertical Jeffcott rotor model with bearing clearances and showed that a small bearing dead-band clearance could have a dramatic influence on synchronous rotor response. Recent test results for a turbopump in a liquid-rocket-engine development program showed a twice-running-speed response (2E) on the order of 8 gs over a wide speed range, while synchronous response levels were only at an 0.5 g level. Childs [2] predicted a sharp 2E response for the Advanced Technology Development, High-Pressure Fuel Turbopump (ATD-HPFTP) of the Space Shuttle Main Engine due to bearing clearances, when the running speed was nearly one half of a housing-mode natural frequency, i.e., when the 2E frequency was close to the housing mode natural frequency. However, his model did not predict significant 2E response over a broad running-speed range. Ellipticity of the bearing dead-band clearances was suggested as a possible cause for the observed 2E phenomenon. An extension of Yamamoto's analysis [1] is presented including bearing ellipticity to examine that proposed explanation. The analysis results show that clearance ellipticity will produce 2E response over a considerable running-speed range during which the bearing clearance is engaged; however, the predicted 2E-response amplitude corresponding to an ellipticity of 0.1 were about 10% of the synchronous levels, and the projected 2E acceleration levels were about 40% of synchronous. The predicted 2E response includes a resonance peak (that can be sharp) at speeds slightly above 25% of the rotor critical speed. The perturbation-analysis results provide an explanation for persistent, lower 2E-response levels observed in many turbopumps, but do not explain the high levels observed with this turbopump.
Synthesis and characterization of metal tungstates by novel solid-state metathetic approach

Abstract Novel solid state metathetic approach (SSM) (ACl 2 + Na 2 WO 4 → AWO 4 + 2NaCl, A = Ca, Sr, Ba, Zn, Mn, Ni) assisted by microwave energy has been successfully applied to the synthesis of tungstates of scheelite- and wolframite-type that are of technological importance. Well crystalline phases of scheelite-type tungstates, MWO 4 (M = Ca, Sr, Ba) have been synthesized where the characteristics of SSM reaction and the formation of high lattice energy by-product NaCl drives the reaction toward completion. Among wolframite-type tungstates, single-phase ZnWO 4 is synthesized by SSM reactions at ambient conditions and MWO 4 (M = Ni, Mn) are synthesized after subjecting the amorphous product to moderate temperature of heating (around 500 °C for 6 h). This alternative method of synthesis where the metathesis reactions proceed in solid state has features like: simple method of synthesis, cost-effectiveness, high yield, easy scale up, and thus has advantages over already known methods of synthesis.
Dust Distribution in Gas Disks: A Model for the Ring around HR 4796A

There have been several model analyses of the near- and mid-IR flux from the circumstellar ring around HR 4796A. In one set of models, the 10 and 18 μm IR flux has been attributed to the reprocessing of stellar radiation by micron-size particles. Since these particles are being blown away, on a dynamical timescale, by the radiation pressure of HR 4796A, they must be continually replenished by the collisional fragments of larger particles. If the ring appearance persisted for the life span (8 × 106 yr) of HR 4796A, a parent-particle reservoir with a total mass greater than 300 M⊕ would be needed. In order to avoid being conspicuous at longer wavelengths, most of the mass must be contained in parent particles larger than 20-40 cm. In other models, it has been suggested that the IR flux from the rings is emitted by sufficiently large particles that survive the radiative blowout by their host star. In a gas-free ring, greater than 3.2 μm size particles would survive radiative blowout and a total of 10-2 M⊕ would be adequate to account for the observed IR flux. But, in the vicinity of a young star, the possibility that the dust ring is embedded within a residual protostellar gas disk cannot be ruled out. In a gas-rich environment, larger sizes (>100 μm) are needed for the particles to survive the radiative blowout. The total dust mass required to account for the IR flux is less than 10-1 M⊕. The combined influence of gas and stellar radiation may also account for the observed sharp inner boundary and rapidly fading outer boundary of the ring. The pressure gradient induced by a small (10%) amplitude variation in the surface density distribution of a low-mass gaseous disk would be sufficient to modify the rotation speed of the gas. The resulting hydrodynamic drag on modest-size (>100 μm) particles would be adequate to compensate for the turbulent stirring, radiative drag, and radiation pressure such that they remain gravitationally bound to the system. The required surface density variation of the gas may be induced by (1) the perturbation of a low-mass planet or the binary companion HR 4796B, (2) the photoevaporation of the disk, or (3) the variations in the viscous angular momentum transport and mass diffusion rate in the disk. We show that the structure of the dust ring is preserved during and after the gas is being depleted such that similar rings may be common among early-type stars.
Surveys of Galaxy Clusters with the Sunyaev Zel'dovich Effect

We have created mock Sunyaev-Zel'dovich effect (SZE) surveys of galaxy clusters using high-resolution N-body simulations. To the pure surveys, we add "noise" contributions appropriate to instrument and primary cosmic microwave background anisotropies. Applying various cluster finding strategies to these mock surveys, we generate catalogs that can be compared to the known positions and masses of the clusters in the simulations. We thus show that the completeness and efficiency that can be achieved depend strongly on the frequency coverage, noise, and beam characteristics of the instruments, as well as on the candidate threshold. We study the effects of matched filtering techniques on completeness and bias. We suggest a gentler filtering method than matched filtering in single-frequency analyses. We summarize the complications that arise when analyzing the SZE signal at a single frequency and assess the limitations of such an analysis. Our results suggest that some sophistication is required when searching for "clusters" within an SZE map.
Frequency preference in two-dimensional neural models: a linear analysis of the interaction between resonant and amplifying currents

Many neuron types exhibit preferred frequency responses in their voltage amplitude (resonance) or phase shift to subthreshold oscillatory currents, but the effect of biophysical parameters on these properties is not well understood. We propose a general framework to analyze the role of different ionic currents and their interactions in shaping the properties of impedance amplitude and phase in linearized biophysical models and demonstrate this approach in a two-dimensional linear model with two effective conductances g L and g 1. We compute the key attributes of impedance and phase (resonance frequency and amplitude, zero-phase frequency, selectivity, etc.) in the g L ???g 1 parameter space. Using these attribute diagrams we identify two basic mechanisms for the generation of resonance: an increase in the resonance amplitude as g 1 increases while the overall impedance is decreased, and an increase in the maximal impedance, without any change in the input resistance, as the ionic current time constant increases. We use the attribute diagrams to analyze resonance and phase of the linearization of two biophysical models that include resonant (I h or slow potassium) and amplifying currents (persistent sodium). In the absence of amplifying currents, the two models behave similarly as the conductances of the resonant currents is increased whereas, with the amplifying current present, the two models have qualitatively opposite responses. This work provides a general method for decoding the effect of biophysical parameters on linear membrane resonance and phase by tracking trajectories, parametrized by the relevant biophysical parameter, in pre-constructed attribute diagrams.
Tests of general relativity using Starprobe radio metric tracking data

The potential of a proposed spacecraft mission, called Starprobe, for testing general relativity and providing information on the interior structure and dynamics of the sun is investigated. Parametric, gravitational perturbation terms are derived which represent relativistic effects and effects due to spatial and temporal variations in the solar potential at a given radial distance. A covariance analysis based on Kalman filtering theory predicts the accuracies with which the free parameters in the perturbation terms can be estimated with radio metric tracking data through the process of trajectory reconstruction. It is concluded that Starprobe can contribute significant information on both the nature of gravitation and the structure and dynamics of the solar interior.
Analysis of pointer “rotation”

Two high-level pointer operations, rotation and slide, reduce conceptual difficulties when writing pointer programs and increase the reliability of programs. We analyze theoretically as well as empirically why these operations are more convenient and introduce a mechanically checkable notion of the safety of rotations. Several examples show that safety is a good indication of program correctness. Examples of list marking and list copying programs demonstrate the utility of these operations.