cssi/SciSciGPT-SciSciNet huggingface dataset:
Attitude Propagation for a Slewing Angular Rate Vector

Attitude propagation typically involves only two coordinate frames one inertial and the other fixed with the vehicle body. If the angular rate vector maintains a fixed direction, attitude propagation is relatively easy. However, slewing or coning angular rate vectors cause difficulties in propagating attitude. As a result, coning algorithms have been developed to reduce coning error. In this work, a new method to propagate vehicle attitude is proposed. It employs an additional coordinate system that slews with the angular rate vector. In this intermediate slewing reference frame the angular rate vector is fixed, thereby eliminating coning error. The method improves attitude propagation accuracy. For pure coning motion, there is no propagation error using this new method.
Comparing D-branes to black-branes☆

Abstract We calculate the potential between two different stationary D-branes and the velocity dependent potential between two different moving D-branes. We identify configurations with some unbroken supersymmetry, using a zero force condition. The potentials are compared with an eleven dimensional calculation of the scattering of a zero black-brane from the 0, 2, 4 and 6 black-brane of type IIA supergravity. The agreement of these calculations provide further evidence for the D-brane description of black-branes, and for the eleven dimensional origin of type IIA string theory.
The slowly rotating near extremal D1–D5 system as a ‘hot tube’

Abstract The geometry of the D1–D5 system with a small angular momentum j has a long throat ending in a conical defect. We solve the scalar wave equation for low energy quanta in this geometry. The quantum is found to reflect off the end of the throat, and stay trapped in the throat for a long time. The length of the throat for j =1/2 equals n 1 n 5 R , the length of the effective string in the CFT; we also find that at this distance the incident wave becomes nonlinear. Filling the throat with several quanta gives a ‘hot tube’ which has emission properties similar to those of the near extremal black hole.
New approaches for modeling Type Ia supernovae

Type Ia supernovae (SNe Ia) are the largest thermonuclearexplosions in the Universe. Their light output can be seen across greatstances and has led to the discovery that the expansion rate of theUniverse is accelerating. Despite the significance of SNe Ia, there arestill a large number of uncertainties in current theoretical models.Computational modeling offers the promise to help answer the outstandingquestions. However, even with today's supercomputers, such calculationsare extremely challenging because of the wide range of length and timescales. In this paper, we discuss several new algorithms for simulationsof SNe Ia and demonstrate some of their successes.
An Economic Theory of Planned Obsolescence

"Planned Obsolescence" is the production of goods with uneconomically short useful lives so that customers will have to make repeat purchases. However, rational customers will pay for only the present value of the future services of a product. Therefore, profit maximization seemingly implies producing any given flow of services as cheaply as possible, with production involving efficient useful lives. This paper shows why this analysis is incomplete and therefore incorrect. Monopolists are shown to desire uneconomically short useful lives for their goods. Oligopolists have the monopolist's incentive for short lives as well as a second incentive that may either increase or decrease their chosen durability. However, oligopolists can generally gain by colluding to reduce durability and increase rentals relative to sales. Some evidence is presented that appears to be generally consistent with the predictions of the theory.
Axisymmetric gravitational solutions as possible classical backgrounds around closed string mass distributions

Abstract By studying singularities in stationary axisymmetric Kerr and Tomimatsu–Sato solutions with distortion parameter δ = 2, 3, … in general relativity, we conclude that these singularities can be regarded as nothing other than closed string-like circular mass distributions. We use two different regularizations to identify δ -function type singularities in the energy–momentum tensor for these solutions, realizing a regulator independent result. This result gives supporting evidence that these axisymmetric exact solutions may well be the classical solutions around closed string-like mass distributions, just like Schwarzschild solution corresponding to a point mass distribution. In other words, these axisymmetric exact solutions may well provide the classical backgrounds around closed strings.
Complete Stability Map of First Order - Two Time Delay Systems with Delay Cross-Talk

First order linear time invariant dynamics is taken into account with two delays. What makes this class of dynamics unique, from the stability perspective, is the added term representing the cross-talk between the two delays. Such delay cross-talk may practically arise due to interference of controller gains in full state feedback with states being inevitably delayed. This class of systems can be treated for their stability by a unique procedure, which is recently developed, known as cluster treatment of characteristic roots (CTCR). In the text we present several case studies to display the steps and the strengths of CTCR. We also include some comparison results with respect to a cornerstone study of Hale and Huang, 1993, which gives a wonderful point of reference for this class of systems, however without the delay cross-talk effect.
Ground-reference calibration of Landsat-7 ETM+

Ground-reference techniques for the Enhanced Thematic Mapper Plus (ETM+) on Landsat 7 are described. The techniques are similar to those used for many years for Landsat-5 Thematic Mapper (TM). Recent results with the Landsat-5 TM are presented, including comparisons with hyperspectral, airborne imaging data. These results show that the Landsat sensor has remained stable within the 5% uncertainty of the ground- reference methods for the last five years. The airborne imagery is also used to show uncertainties due to registration errors, spectral differences, and spatial resolution differences in cross-comparison techniques planned for Earth Observing System sensors. In addition to the use of the traditional methods and test sites, a smaller test site local to the University of Arizona area is being evaluated for use with ETM+. This site, while not as bright, spatially- uniform and large as typical sites, allows more frequent calibrations and hopefully a better understanding of the calibration as a function of time. The selection of the test site, its properties, and example results of calibration of Landsat-5 TM are presented.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
GUT scale and leptogenesis from 5D inflation

Abstract We discuss a five-dimensional inflationary scenario based on a supersymmetric SO (10) model compactified on S 1 /( Z 2 × Z 2 ′). Inflation is implemented through scalar potentials on four-dimensional branes, and a brane-localized Einstein–Hilbert term is essential to make both brane vacuum energies positive during inflation. The orbifold boundary conditions break the SO (10) gauge symmetry to SU (4) c × SU (2) L × SU (2) R (≡ H ). The inflationary scenario yields δT / T ∝( M / M Planck ) 2 , which fixes M , the symmetry breaking scale of H to be close to the SUSY GUT scale of 10 16 GeV. The scalar spectral index n is 0.98–0.99, while the gravitational wave contribution to the quadrupole anisotropy is negligible (≲1%). The inflaton decay into the lightest right-handed neutrinos yields the observed baryon asymmetry via leptogenesis.
High-energy behavior of non-Abelian gauge theories

This paper is a detailed account of a study in perturbation theory of the high-energy behavior of non-Abelian gauge theories. We calculate the fermion-fermion scattering amplitude up to sixth order in the coupling constant in the high-energy limit $s\ensuremath{\rightarrow}\ensuremath{\infty}$ with fixed $t$, in the approximation of keeping only the leading logarithmic terms. Our results indicate that the high-energy behavior of non-Abelian gauge theories are complicated, and quite different from the known behaviors of other field theories studied so far.
Symmetric charge transfer in low-energy ion-atom collisions

Previous calculations of ion-atom interactions by the pseudopotential and asymptotic methods are used in the computation of the cross section for symmetric charge transfer at energies below 1 keV. The results for ${\mathrm{Li}}^{+}$, ${\mathrm{Na}}^{+}$, ${\mathrm{K}}^{+}$, ${\mathrm{Rb}}^{+}$, ${\mathrm{Cs}}^{+}$, and ${\mathrm{Ca}}^{+}$ ions are compared with data obtained in beam experiments, and by optical-pumping techniques. The difference in the cross sections for $^{2}P_{\frac{1}{2}}$ and $^{2}P_{\frac{3}{2}}$ ions of ${\mathrm{Kr}}^{+}$ and ${\mathrm{Xe}}^{+}$ at thermal energies is studied, and the predictions are compared with recent mobility measurements. Cross sections are obtained for ${\mathrm{U}}^{+}$-U collisions, and the dependence of the thermal cross section on the polarizability is described. Symmetric charge transfer of the negative ions ${\mathrm{H}}^{\ensuremath{-}}$, ${\mathrm{Na}}^{\ensuremath{-}}$, and ${\mathrm{Cs}}^{\ensuremath{-}}$ is discussed briefly.
Stochastic evolution equations for nonlinear filtering of random fields in the presence of fractional Brownian sheet observation noise

The problem of nonlinear filtering of a random field observed in the presence of a noise, modeled by a persistent fractional Brownian sheet of Hurst index (H"1,H"2) with 0.5=3.
Videodensitometry of osteons in females with femoral neck fractures

The medial femoral cortices of 10 females with femoral neck fractures and 10 age-matched female autopsy cases were studied using computer-assisted videodensitometry. Radiographic mineral density was determined using the calibration method described by Martin et al. [20]. Measurements were made of porosity, osteon and haversian canal dimensions, and of interstitial and osteon mineral density across the cortical wall of the orthopedic calcar region. There were no differences between the fracture and nonfracture groups in the overall mean mineral density of the bone averaged over the microstructure, excluding pore space, or in the interstitial bone mineral density. The porosity in the fracture group was greater than in the autopsy group, especially in the periosteal region, where the porosity was 2.4 times greater and where there were also 27% fewer osteons per unit area than in the autopsy group (P<0.05). Mean osteon mineral density was 2.5% higher in the fracture group (P<0.05) compared with the autopsy group in the endosteal region, and 4% higher in the periosteal region. Osteon and haversian canal areas were also larger in the fracture group, especially in the middle region of the cortical wall (17% and 23%, respectively, P<0.05).
Inverse Hyperbolic Problems and Optical Black Holes

In this paper we state a uniqueness theorem for the inverse hyperbolic problem in the case of a finite time interval. We apply this theorem to the inverse problem for the equation of the propagation of light in a moving medium (the Gordon equation). Then we study the existence of black and white holes for the general second order hyperbolic equation and for the Gordon equation and we discuss the impact of this phenomenon on the inverse problems.
Optimal Angle Bounds for Quadrilateral Meshes

We show that any simple planar n-gon can be meshed in linear time by O(n) quadrilaterals with all new angles bounded between 60 and 120 degrees.
Lopsided spiral galaxies and a limit on the galaxy accretion rate

We present a measurement of lopsidedness for the stellar disks of 60 field spiral galaxies in terms of the azimuthal m = 1 Fourier amplitude, A1, of the stellar light. We confirm the previous result (Rix & Zaritsky) that ~30% of field spiral galaxies in a magnitude-limited sample exhibit significant lopsidedness (A1/A0 ≥ 0.2) at large radii (R > 1.5 disk scalelengths). We conjecture that this lopsidedness is caused by tidal interactions and calculate an upper limit on the accretion rate of small galaxies. We exploit the correlation between lopsidedness and photometric measures of recent star formation (Zaritsky) to obtain two independent estimates of the lifetime of these m = 1 distortions. First, we show that lopsided galaxies have an excess of blue luminosity relative to that of symmetric galaxies with the same H I linewidth, which we attribute to a recent star formation episode that was triggered by an interaction between the galaxy and a companion. We use stellar population models (Bruzual & Charlot) to estimate the time since that interaction. Second, we use the N-body simulation of an infalling satellite by Walker, Mihos, & Hernquist to estimate how fast tidally induced m = 1 distortions are erased through phase mixing. Both approaches indicate that the observations are consistent with a hypothesized tidal interaction that occurred about 1 Gyr ago for galaxies that are lopsided at the 20% level. By combining this lifetime estimate for lopsidedness, the observed frequency of such distortions, and a correction to the survey volume that depends on the increase in luminosity during an interaction, we derive an upper limit on the current companion accretion rate of field spiral galaxies (for companion masses ~10% parent galaxy mass) that lies in the range 0.07-0.25 Gyr-1. The principal uncertainty in this limit arises from ambiguities in the interpretation of the correlation between lopsidedness and MB.
Systems information management: graph theoretical approach

This study proposes a new method for characterising the underlying information structure of a multi-sector system. A complete characterisation is accomplished by identifying information gaps and cause-effect information pathways in the system, and formulating critical testable hypotheses. Graph-theoretical concepts and principles of systems theory are heavily exploited in this characterisation. The application of the method is illustrated with an experimental workshop in which a multi-voting scheme is carried out to identify the gaps, pathways, and hypotheses. The method should find wide applications in modelling information structures implied by qualitative expert knowledge.
Enantioselective Synthesis of α-Amino Nitriles from N-Benzhydryl Imines and HCN with a Chiral Bicyclic Guanidine as Catalyst

A novel catalytic enantioselective Strecker synthesis of chiral α-amino nitriles and α-amino acids is described and analyzed with regard to the possible mechanistic basis for stereoselectivity. Key features of the enantioselective process include (1) the use of the chiral bicyclic guanidine 1 as catalyst and (2) the use of the N-benzhydryl substituent on the imine substrate.
On field theory thermalization from gravitational collapse

Motivated by its field theory interpretation, we study gravitational collapse of a minimally coupled massless scalar field in Einstein gravity with a negative cosmological constant. After demonstrating the accuracy of the numerical algorithm for the questions we are interested in, we investigate various aspects of the apparent horizon formation. In particular, we study the time and radius of the apparent horizon formed as functions of the initial Gaussian profile for the scalar field. We comment on several aspects of the dual field theory picture.
Program interrupt on the Univac scientific computer

In the use of high-speed digital computers the general situation has been to have the program or the programmer at the console in sole control of what the machine is doing. In recent years, however, a situation has often occurred where a program, so to speak, has only been lent the machine until a higher priority problem is ready to go on the machine. At these times the machine was stopped, the low priority problem was taken off the machine, and the high priority problem was allowed to run. Though such a situation is preferable to having a computer idle while it awaits the high priority problem, the time lost in getting the old problem off and the new problem on has been an unfortunate loss.
First-principles study of Zn-Sb thermoelectrics

We report local-density-approximation calculations of the electronic structure and thermoelectric properties of $\ensuremath{\beta}\ensuremath{-}{\mathrm{Zn}}_{4}{\mathrm{Sb}}_{3}$. The material is a low carrier density metal with a complex Fermi-surface topology and a nontrivial dependence of the Hall concentration on the band filling. The band structure is rather covalent, consistent with experimental observations of good carrier mobility. At a band filling corresponding to the experimental Hall number, the calculated thermopower and temperature dependence are in good agreement with experiment. The high Seebeck coefficient in a metallic material is remarkable, and arises in part from the strong energy dependence of the Fermi surface topology near the experimental band filling. An improved thermoelectric performance is predicted for lower doping levels, i.e., higher Zn concentrations.
First Tests of Wavefront Sensing with a Constellation of Laser Guide Beacons

Adaptive optics to correct current telescopes over wide fields, or even to correct future very large telescopes over narrow fields, will require real-time wavefront measurements made with a constellation of laser beacons. Here we report the first such measurements, made at the 6.5 m MMT with five Rayleigh beacons in a 2' pentagon. Each beacon is made with a pulsed beam at 532 nm of 4 W at the exit pupil of the projector. The return is range-gated from 20 to 29 km and recorded at 53 Hz by a 36-element Shack-Hartmann sensor. Wavefronts derived from the beacons are compared with simultaneous wavefronts obtained for individual natural stars within or near the constellation. Observations were made in seeing averaging 10 with two-thirds of the aberration measured to be from a ground layer of mean height 380 m. Under these conditions, subtraction of the simple instantaneous average of the five beacon wavefronts from the stellar wavefronts yielded a 40% rms reduction in the measured modes of the distortion over a 2' field. We discuss the use of multiple Rayleigh beacons as an alternative to single sodium beacons on 8 m telescopes and the impact of the new work on the design of a multi-sodium beacon system for the 25 m Giant Magellan Telescope.
Incidental Findings: A Common Law Approach

Federal regulations governing human subjects research do not address key questions raised by incidental neuroimaging findings, including the scope of a researcher's disclosure with respect to the possibility of incidental findings and the question whether a researcher has an affirmative legal cuty to seek, detect, and report incidental findings. The scope of researcher duties may, however, be mapped with reference to common law doctrine, including fiduciary, tort, contract, and bailment theories of liability.
Simplified Computational Models for Shear Compliant Borders in Solar Sails

Shear compliant regions have been demonstrated to reduce both the amplitude and extent of structural wrinkles on the surface of thin-film (Gossamer) membranes under simultaneous tension and shear. Rather than modeling the full geometric details of the thermoformed strips that comprise a shear compliant region, two simplified approaches have been developed for efficiently incorporating them into existing finite element models. One approach replaces the three-dimensional geometry of the thermoformed region with alternating flat strips of high E/ν~0.3 and low E/ν~0 materials. The other approach uses a properly aligned uniaxial orthotropic material to model the behavior of the shear compliant region. Both approaches were simulated in finite element software, and yielded similar results that (at least qualitatively) reflected the behavior of existing test articles containing thermoformed shear compliant regions.
β-Aminoethyltrifluoroborates: Efficient Aminoethylations via Suzuki-Miyaura Cross-Coupling

A set of phenethylamines has been successfully prepared via Suzuki−Miyaura cross-coupling of diverse potassium β-aminoethyltrifluoroborates with aryl halides. The potassium β-aminoethyltrifluoroborates were easily prepared via hydroboration of enamine and enamide precursors.
Local index theory over foliation groupoids

We give a local proof of an index theorem for a Dirac-type operator that is invariant with respect to the action of a foliation groupoid G .I fM denotes the space of units of G then the input is a G-equivariant fiber bundle P → M along with a G-invariant fiberwise Dirac-type operator D on P. The index theorem is a formula for the pairing of the index of D ,a s an element of a certain K-theory group, with a closed graded trace on a certain noncommutative de Rham algebra ∗ B associated to G. The proof is by means of superconnections in the framework of noncommutative geometry.
Excellence in computer simulation

Excellent computer simulations are done for a purpose. The most valid purposes are to explore uncharted territory, to resolve a well-posed scientific or technical question, or to make a good design choice. Stand-alone modeling can serve the first purpose; the other two goals need a full integration of the modeling effort into a scientific or engineering program. Some excellent work, much of it related to the US Department of Energy's laboratories, is reviewed. Some less happy stories are recounted.
On exchangeable random variables and the statistics of large graphs and hypergraphs

De Finetti’s classical result of [18] identifying the law of an exchangeable family of random variables as a mixture of i.i.d. laws was extended to structure theorems for more complex notions of exchangeability by Aldous [1, 2, 3], Hoover [41, 42], Kallenberg [44] and Kingman [47]. On the other hand, such exchangeable laws were first related to questions from combinatorics in an independent analysis by Fremlin and Talagrand [29], and again more recently in Tao [62], where they appear as a natural proxy for the ‘leading order statistics’ of colourings of large graphs or hypergraphs. Moreover, this relation appears implicitly in the study of various more bespoke formalisms for handling ‘limit objects’ of sequences of dense graphs or hypergraphs in a number of recent works, including Lovasz and Szegedy [52], Borgs, Chayes, Lovasz, Sos, Szegedy and Vesztergombi [17], Elek and Szegedy [24] and Razborov [54, 55]. However, the connection between these works and the earlier probabilistic structural results seems to have gone largely unappreciated. In this survey we recall the basic results of the theory of exchangeable laws, and then explain the probabilistic versions of various interesting questions from graph and hypergraph theory that their connection motivates (particularly extremal questions on the testability of properties for graphs and hypergraphs). We also locate the notions of exchangeability of interest to us in the context of other classes of probability measures subject to various symmetries, in particular contrasting the methods employed to analyze exchangeable laws with related structural results in ergodic theory, particular the Furstenberg-Zimmer structure theorem for probability-preserving ℤ-systems, which underpins Furstenberg’s ergodic-theoretic proof of Szemeredi’s Theorem. The forthcoming paper [10] will make a much more elaborate appeal to the link between exchangeable laws and dense (directed) hypergraphs to establish various results in property testing.
Reasoning with higher-order abstract syntax in a logical framework

Logical frameworks based on intuitionistic or linear logics with higher-type quantification have been successfully used to give high-level, modular, and formal specifications of many important judgments in the area of programming languages and inference systems. Given such specifications, it is natural to consider proving properties about the specified systems in the framework: for example, given the specification of evaluation for a functional programming language, prove that the language is deterministic or that evaluation preserves types. One challenge in developing a framework for such reasoning is that higher-order abstract syntax (HOAS), an elegant and declarative treatment of object-level abstraction and substitution, is difficult to treat in proofs involving induction. In this article, we present a meta-logic that can be used to reason about judgments coded using HOAS; this meta-logic is an extension of a simple intuitionistic logic that admits higher-order quantification over simply typed λ-terms (key ingredients for HOAS) as well as induction and a notion of definition. The latter concept of definition is a proof-theoretic device that allows certain theories to be treated as "closed" or as defining fixed points. We explore the difficulties of formal meta-theoretic analysis of HOAS encodings by considering encodings of intuitionistic and linear logics, and formally derive the admissibility of cut for important subsets of these logics. We then propose an approach to avoid the apparent trade-off between the benefits of higher-order abstract syntax and the ability to analyze the resulting encodings. We illustrate this approach through examples involving the simple functional and imperative programming languages PCF and PCF:=. We formally derive such properties as unicity of typing, subject reduction, determinacy of evaluation, and the equivalence of transition semantics and natural semantics presentations of evaluation.
Compact zwitterion-coated iron oxide nanoparticles for in vitro and in vivo imaging.

We have recently developed compact and water-soluble zwitterionic dopamine sulfonate (ZDS) ligand coated superparamagnetic iron oxide nanoparticles (SPIONs) for use in various biomedical applications. The defining characteristics of ZDS-coated SPIONs are small hydrodynamic diameters, low non-specific interactions with fetal bovine serum, the opportunity for specific labeling, and stability with respect to time, pH, and salinity. We report here on the magnetic characterization of ZDS-coated SPIONs and their in vitro and in vivo performance relative to non-specific interactions with HeLa cells and in mice, respectively. ZDS-coated SPIONs retained the superparamagnetism and saturation magnetization (Ms) of as-synthesized hydrophobic SPIONs, with Ms = 74 emu g−1 [Fe]. Moreover, ZDS-coated SPIONs showed only small non-specific uptake into HeLa cancer cells in vitro and low non-specific binding to serum proteins in vivo in mice.
Neutrino masses and mixings in non-factorizable geometry

We study bulk fermion fields in the localized gravity model with non-factorizable metric recently proposed by Randall and Sundrum, and Gogberashvili. In addition to a tower of weak-scale Kaluza–Klein states we find a zero mode for any value of the fundamental fermion mass. If the fermion mass is larger than half the curvature of the compact dimension, the zero mode can be localized on the “hidden” 3-brane in the Randall–Sundrum model. Identifying this mode with a right-handed neutrino provides a new way for obtaining small Dirac neutrino masses without invoking a see-saw mechanism. Cancellation of the parity anomaly requires introducing an even number of bulk fermions. This naturally leads to a strong hierarchy of neutrino masses and generically large mixing angles.
Quantification and Mitigation of Long-Term Impacts of Urbanization and Climate Change in the Tropical Coastal City of San Juan, Puerto Rico

Urbanization, along with other cases of land cover and land use changes, has significant climate impacts in tropical regions with the added complexity of occurring within the context of global warming (GW). The individual and combined effects of these two factors on the surface energy balance of a tropical city are investigated by the use of an integrated atmospheric modeling approach, taking the San Juan Metropolitan Area (SJMA), Puerto Rico, as the test case. To achieve this goal, an ensemble of climate and weather simulations is performed, with climate scenarios combining urban development and sprawl with regional climate change over the past 50 years and the short-term simulations designed to test the sensitivity to different urban vegetation configurations as mitigating alternatives. As indicator of change, we use the thermal response number (TRN), which is a measure of the sensible heating to the thermal storage of a surface or region, and the Bowen ratio, which is defined as the ratio of sensible to latent heat fluxes. The TRN of the area occupied by the SJMA has decreased as a consequence of replacing the lowland coastal plain vegetation with man-made materials, indicating that it takes less energy to raise the surface temperature of the urban area, whereas the TRN of forested regions has remained virtually unchanged. The GW signal also has effects on the thermal response of the SJMA, where dryer current conditions generate lower TRN values. Differences owing to GW are more evident in the Bowen ratio pattern, mostly associated with the drier present conditions observed and its effects on sensible and latent heat fluxes. In terms of testing different mitigation strategies, the short-term simulations show that the urban area is more efficient in partitioning surface energy balance terms when green roofs are specified, as opposed to including vegetation inside the urban core.
Readability of Asthma Web Sites

Background. Asthma is the most prevalent chronic illness affecting 10% of the pediatric population. The internet is a useful tool for acquiring information on health topics. In a recent Harris Poll, 154 million adults searched the Internet for health information. The usefulness of asthma materials on the Internet depends on the ability to read and comprehend the information. The goal of this study was to assess the readability of asthma Web sites. Methods. The authors studied the readability of 6 asthma Web sites that have been previously evaluated for quality and accuracy of information. The Flesch/Flesch-Kincaid tools were used to evaluate readability and reading ease of the materials on each of the Web sites with the use of Microsoft Office Word software. Results. Materials included in the 6 Web sites were analyzed. The information included in the Web sites had a readability index between 46.6 and 63.5, with a mean of 54.33 on the Flesch reading ease. The mean Flesch-Kincaid grade level was found to be...
Preparation and nitrosation of 3,4‐dimethyl‐3‐penten‐2‐one (e)‐ and (z)‐oximes. Formation of 3,3,4,5‐tetramethyl‐3H‐pyrazole 1,2‐dioxide and of 2‐isoxazoline derivatives

The stereoisomeric (E)- and (Z)-oximes of 3,4-dimethyl-3-penten-2-one were prepared and nitrosated with butyl nitrite in methanol. The (E)-oxime gave 3,3,4,5-tetramethyl-3H-pyrazole 1,2-dioxide in nearly quantitative yield, while the (Z)-oxime reacted less readily, giving a lower yield of the same product, with five other products identified as isoxazoline derivatives. Three of these were 4-hydroxy-, 4-methoxy-, and 4-nitro-3,4,5,5-tetramethyl-2-isoxazoline. The fourth was the O-(3,4,5,5-tetramethyl-2-isoxazolin-4-yl) derivative of the starting (Z)-oxime, and the fifth was 4-methylene-3,5,5-trimethyl-2-isoxazoline.
Trend toward multiple authors in research publications: Mutual funding of scientists

In a recent editorial, Leopold [1979] drew attention to the large amount of time now being spent by the U.S. research community on the preparation and review of research proposals submitted to the principal federal granting agencies. More to the point of this letter, he quoted a ‘fanciful story’ by Szilard [1961] in which it was suggested that if some person or some group should ever want to bring research progress to a standstill, they could do so by establishing a competitive grants system under which all researchers would be required to prepare written proposals describing what they wished to work on. Leopold ended by suggesting that ‘perhaps it is now appropriate to ask whether Szilard's fanciful story is turning into a serious matter.’ If there is any substance to Szilard's story and Leopold's concern, there should be evidence now available for a slowing down in the progress of U.S. science, since federal grants for research started to become a substantial factor in university budgets in the late fifties [Abelson, 1975]. Unfortunately, lacking a means of quantifying progress in science, it is difficult to argue objectively either for or against this slowing down. However, as I will now show, there has been a marked change in the way science is reported since the fifties.
Optical afterglows of Gamma-Ray Bursts: peaks, plateaus, and possibilities

The optical light curves of gamma-ray burst (GRB) afterglows display either peaks or plateaus. We identify 16 afterglows of the former type, 17 of the latter and four with broad peaks, which could be of either type. The optical energy release of these two classes is similar and is correlated with the GRB output, the correlation being stronger for peaky afterglows, which suggests that the burst and afterglow emissions of peaky afterglows are from the same relativistic ejecta and that the optical emission of afterglows with plateaus arises more often from ejecta that did not produce the burst emission. Consequently, we propose that peaky optical afterglows are from impulsive ejecta releases and that plateau optical afterglows originate from long-lived engines, the break in the optical light curve (peak or plateau end) marking the onset of the entire outflow deceleration. In the peak luminosity-peak time plane, the distribution of peaky afterglows displays an edge with Lp ∝ t ―3 p , which we attribute to variations (among afterglows) in the ambient medium density. The fluxes and epochs of optical plateau breaks follow an L b ∝ t ―1 b anticorrelation. Sixty per cent of 25 afterglows that were well monitored in the optical and X-rays show light curves with comparable power-law decay indices and achromatic breaks. The other 40 per cent display three types of decoupled behaviours: (1) chromatic optical light-curve breaks (perhaps due to the peak of the synchrotron spectrum crossing the optical), (2) X-ray flux decays faster than in the optical (suggesting that the X-ray emission is from local inverse-Compton scattering) and (3) chromatic X-ray light-curve breaks (indicating that the X-ray emission is from external upscattering).
A temporally abstracted Viterbi algorithm

Hierarchical problem abstraction, when applicable, may offer exponential reductions in computational complexity. Previous work on coarse-to-fine dynamic programming (CFDP) has demonstrated this possibility using state abstraction to speed up the Viterbi algorithm. In this paper, we show how to apply temporal abstraction to the Viterbi problem. Our algorithm uses bounds derived from analysis of coarse timescales to prune large parts of the state trellis at finer timescales. We demonstrate improvements of several orders of magnitude over the standard Viterbi algorithm, as well as significant speedups over CFDP, for problems whose state variables evolve at widely differing rates.
Age, socioeconomic status and obesity growth

We use panel data from the National Longitudinal Survey of Youth (NLSY) to examine how body weight changes with age for a cohort moving through early adulthood, to investigate how the age-obesity gradient differs with socioeconomic status (SES) and to study channels for these SES disparities. Our results show first that weight increases with age and is inversely related to SES during childhood. Second, the obesity gradient widens over the lifecycle, consistent with research on other health outcomes. Third, a substantial portion of the "effect" of early life conditions operates through race/ethnicity and the translation of advantaged family backgrounds during childhood into higher levels of subsequent education. By contrast, little of the SES gap appears to propagate through household composition, family income or health behaviors. Fourth, adult SES has independent effects after controlling for childhood status.
Informational integration and FX trading

Abstract This paper addresses international financial integration in a new way. We focus on informational integration, specifically, the importance of information conveyed by order flow in major currencies for pricing minor currencies. We develop a multi-currency model of portfolio allocation in the presence of dispersed information. We then test the model’s implications using four months of concurrent transaction data on nine currencies. The model explains 45 to 78% of daily returns in all nine currencies. Moreover, its prediction that order flow in individual markets should be relevant for determining prices in other markets is borne out.
Simultaneous multi-head calibration for pinhole SPECT

Pinhole collimation is used as a magnifying geometry to overcome the resolution constraints of the gamma cameras used in SPECT. It is very sensitive to the mechanical position of the aperture relative to the axis of rotation. It is also sensitive to the axial position of the aperture. When one camera head is used, there is no intrinsic reference point for determining the axial mechanical shift. However, when multiple heads are used, the axial origin can be defined as the center of the first aperture. The other apertures can be measured relative to the first. A procedure has been developed for simultaneously calibrating multiple heads by using a single point source in the field of view of all heads. The gantry is rotated through 360 degrees. The centroids are fit using a maximum-likelihood method to an equation that describes the axial and transaxial geometry. The three coordinates of the point source are determined along with the mechanical and electronic shifts in the axial and transaxial directions; the axial mechanical shift of the first aperture is set to zero by definition. Another advantage of multi-head calibration is that a further constraint on the position of the point source is made. We apply the calibration information to a sub-micro disk phantom with 1.6 mm disks.
On the Longest $k$-Alternating Subsequence

We show that the longest $k$-alternating substring of a random permutation has length asymptotic to $2(n-k)/3$.
Dynamic Inefficiencies in Insurance Markets: Evidence from long-term care insurance *

We examine whether unregulated, private insurance markets efficiently provide insurance against reclassification risk (the risk of becoming a bad risk and facing higher premiums). To do so, we examine the ex-post risk type of individuals who drop their long-term care insurance contracts relative to those who are continually insured. Consistent with dynamic inefficiencies, we find that individuals who drop coverage are of lower risk ex-post than individuals who were otherwise-equivalent at the time of purchase but who do not drop out of their contracts. These findings suggest that dynamic market failures in private insurance markets can preclude the efficient provision of insurance against reclassification risk.
Some extensions of probabilistic logic

First order logic is a very useful tool for knowledge representation, inference engine and AI programming. Recently, Nilsson has proposed the probabilistic logic and a probabilistic inference scheme. We extend it to evidential logic in the Dempster-Shafer fashion. In terms of multidimensional random variables, we observe that the permissible probabilistic interpretation vector of Nilsson consists of the joint probabilities of logical propositions. Thus, probabilistic logic is subsumed by probability theory.
Magnetic circuit model for the mutually coupled switched-reluctance machine

The mutually coupled switched-reluctance motor (SRM) appears to have several performance advantages over other motor technologies. The existence of strong coupling between phases, however, makes the analysis of this machine quite complicated. Preliminary design of this machine can be greatly accelerated by the ability to evaluate potential motor geometries quickly. This paper introduces a general magnetic circuit model of the mutually coupled SRM that adapts to any geometry, unlike existing geometry-dependent approaches (such as finite elements), which are numerically intensive and require excessive computation time. The model uniquely implements the magneto-motive force (mmf) sources necessary to accommodate complex flux paths through the machine and includes the effects of magnetic saturation. The results are compared to those of a finite element solver to demonstrate the performance of this method as a first-step to evaluating candidate designs.
The impact of coffee market reforms on producer prices and price transmission

This paper evaluates the impact of coffee sector reforms during late 1980s and early 1990s on coffee growers in the main coffee producing countries. Earlier evidence suggests that the reforms increased the share of producer prices in the world price of coffee. This hypothesis is tested in the paper with the help of cointegration analysis, and the results show that in most countries the longterm producer price share has indeed increased substantially after the liberalization. Moreover, the results suggest that the reforms induced a closer cointegrating relationship between grower prices and world market prices. Finally, estimation of an error-correction model reveals that short-run transmission of price signals from the world market to domestic producers has improved, such that domestic prices adjust faster today to world price fluctuations than they did prior to the reforms. However, there is some evidence of asymmetries in the way positive and negative world price changes are transmitted to domestic markets.
Interpretation neutrality in the classical domain of quantum theory

I show explicitly how concerns about wave function collapse and ontology can be decoupled from the bulk of technical analysis necessary to recover localized, approximately Newtonian trajectories from quantum theory. In doing so, I demonstrate that the account of classical behavior provided by decoherence theory can be straightforwardly tailored to give accounts of classical behavior on multiple interpretations of quantum theory, including the Everett, de Broglie-Bohm and GRW interpretations. I further show that this interpretation-neutral, decoherence-based account conforms to a general view of inter-theoretic reduction in physics that I have elaborated elsewhere, which differs from the oversimplified and often ambiguous picture that treats reduction simply as a matter of taking limits. This interpretation-neutral account rests on a general three-pronged strategy for reduction between quantum and classical theories that combines decoherence, an appropriate form of Ehrenfest's Theorem, and a decoherence-compatible mechanism for collapse. It also incorporates a novel argument as to why branch-relative trajectories should be approximately Newtonian, which is based on a little-discussed extension of Ehrenfest's Theorem to open systems, rather than on the more commonly cited but less germane closed-systems version. In the Conclusion, I briefly suggest how the strategy for quantum-classical reduction described here might be extended to reduction between other classical and quantum theories, including classical and quantum field theory and classical and quantum gravity.
Dark matter subhalos and the dwarf satellites of the Milky Way

The Via Lactea simulation of the cold dark matter halo of the Milky Way predicts the existence of many thousands of bound subhalos with masses above 106 M?, distributed approximately with equal mass per decade of mass. Here we show that (1) a similar steeply rising subhalo mass function is also present at redshift -->z = 0.5 in an elliptical-sized halo simulated with comparable resolution in a different cosmology. Compared to Via Lactea, this run produces nearly a factor of 2 more subhalos with large circular velocities; (2) the fraction of Via Lactea mass brought in by subhalos that have a surviving bound remnant today reaches 45%. Most of the Via Lactea mass is acquired in resolved discrete clumps, with no evidence for a significant smooth infall; (3) because of tidal mass loss, the number of subhalos surviving today that reached a peak circular velocity of >10 km s?1 throughout their lifetime exceeds half a thousand, 5 times larger than their present-day abundance; (4) unless the circular velocity profiles of Galactic satellites peak at values significantly higher that expected from the stellar line-of-sight velocity dispersion, only about one in five subhalos with -->Vmax > 20 km s?1 today must be housing a luminous dwarf; (5) nearly 600 halos with masses greater than 107M? are found today in the ``field'' between r200 and 1.5r200, i.e. small dark matter clumps appear to be relatively inefficient at forming stars even well beyond the virial radius; 6) the observed Milky Way satellites appear to follow the overall dark matter distribution of Via Lactea, while the largest simulated subhalos today are found preferentially at larger radii; (7) subhalos have central densities that increase with -->Vmax and reach -->?DM = 0.1?0.3 M? pc?3, comparable to the central densities inferred in dwarf spheroidals with core radii >250 pc.
Novel allylic oxidation reagents

Abstract Pentafluorobenzeneseleninic acid and 2-(N-oxido)pyridineseleninic anhydride were prepared and used efficiently in the oxidation of alcohols and in the allylic oxidation of alkenes.
Is there a cosmological constant

The grant contributed to the publication of 18 refereed papers and 5 conference proceedings. The primary uses of the funding have been for page charges, travel for invited talks related to the grant research, and the support of a graduate student, Charles Keeton. The refereed papers address four of the primary goals of the proposal: (1) the statistics of radio lenses as a probe of the cosmological model (#1), (2) the role of spiral galaxies as lenses (#3), (3) the effects of dust on statistics of lenses (#7, #8), and (4) the role of groups and clusters as lenses (#2, #6, #10, #13, #15, #16). Four papers (#4, #5, #11, #12) address general issues of lens models, calibrations, and the relationship between lens galaxies and nearby galaxies. One considered cosmological effects in lensing X-ray sources (#9), and two addressed issues related to the overall power spectrum and theories of gravity (#17, #18). Our theoretical studies combined with the explosion in the number of lenses and the quality of the data obtained for them is greatly increasing our ability to characterize and understand the lens population. We can now firmly conclude both from our study of the statistics of radio lenses and our survey of extinctions in individual lenses that the statistics of optically selected quasars were significantly affected by extinction. However, the limits on the cosmological constant remain at lambda < 0.65 at a 2-sigma confidence level, which is in mild conflict with the results of the Type la supernova surveys. We continue to find that neither spiral galaxies nor groups and clusters contribute significantly to the production of gravitational lenses. The lack of group and cluster lenses is strong evidence for the role of baryonic cooling in increasing the efficiency of galaxies as lenses compared to groups and clusters of higher mass but lower central density. Unfortunately for the ultimate objective of the proposal, improved constraints on the cosmological constant, the next large survey for gravitational lenses did not release its results during the term of the proposal. The research supported the career development. of six graduate students (polar, Fletcher, Herold, Keeton, Deng and Rusin) and two post-docs (Labor and Munoz).