cssi/SciSciGPT-SciSciNet huggingface dataset:
Analysis of STS-2 experimental heating rates and transition data

Experimental laminar and 'fully' turbulent windward-ray heating rates obtained from the second Space Shuttle flight are compared with predicted rates based on equilibrium-air approximate and detailed analyses. A comparison of the results of the prediction techniques yield discrepancies of approximately 10 percent. The experimental laminar heating rates for altitudes greater than 67 km are as much as 35 percent lower than the results of the approximate code over the first 40 percent of the shuttle length. The approximate equilibrium predictions are in good agreement with these laminar data beyond the 40-percent station and over the entire shuttle at altitudes lower than 67 km. However, recent results of a detailed viscous-shock-layer nonequilibrium code indicate significant departures, especially at high altitudes, from the equilibrium state. Since the comparison of these predicted values and the data result in some currently unresolved questions, an engineering correlation of the predictions for use in the approximate code is not feasible at this time. Factors which may affect the comparisons of data and the nonequilibrium predictions are considered. The turbulent heating comparisons are good and boundary-layer transition data are compared with a current boundary-layer transition criterion.
An r-process Kilonova Associated with the Short-hard GRB 130603B

We present ground-based optical and Hubble Space Telescopeoptical and near-IR observations of the shorthard GRB 130603B at z = 0.356, which demonstrate the presence of excess near-IR emission matching the expected brightness and color of an r-process powered trans ient (a “kilonova”). The early afterglow fades rapidly with � . -2.6 at t � 8 - 32 hr post-burst and has a spectral index of � � -1.5 (F� / t � � � ), leading to an expected near-IR brightness at the time of the first HST observation of mF160W(t = 9.4 d) & 29.3 AB mag. Instead, the detected source has mF160W = 25.8± 0.2 AB mag, corresponding to a rest-frame absolute magnitude of MJ � -15.2 mag. The upper limit in the HST optical observations is mF606W & 27.7 AB mag (3�), indicating an unusually red color of V - H & 1.9 mag. Comparing the observed near-IR luminosity to theoretical models of kilonovae produced by ejecta from the merger of an NS-NS or NS-BH binary, we infer an ejecta mass of Mej � 0.03 - 0.08 M⊙ for vej � 0.1 - 0.3c. The inferred mass matches the expectations from numerical merger simulations. The presence of a kilonova provides the strongest evidence to date that short GRBs are produced by compact object mergers, and provides initial insight on t he ejected mass and the primary role that compact object merger may play in the r-process. Equally important, it demonstrates that gravitational wave sources detected by Advanced LIGO/Virgo will be accompanied by optical/near-IR counterparts with unusually red colors, detectable by existing and upcoming large wide-fiel d facilities (e.g., Pan-STARRS, DECam, Subaru, LSST).
Chromatin Loops as Allosteric Modulators of Enhancer-Promoter Interactions

The classic model of eukaryotic gene expression requires direct spatial contact between a distal enhancer and a proximal promoter. Recent Chromosome Conformation Capture (3C) studies show that enhancers and promoters are embedded in a complex network of looping interactions. Here we use a polymer model of chromatin fiber to investigate whether, and to what extent, looping interactions between elements in the vicinity of an enhancer-promoter pair can influence their contact frequency. Our equilibrium polymer simulations show that a chromatin loop, formed by elements flanking either an enhancer or a promoter, suppresses enhancer-promoter interactions, working as an insulator. A loop formed by elements located in the region between an enhancer and a promoter, on the contrary, facilitates their interactions. We find that different mechanisms underlie insulation and facilitation; insulation occurs due to steric exclusion by the loop, and is a global effect, while facilitation occurs due to an effective shortening of the enhancer-promoter genomic distance, and is a local effect. Consistently, we find that these effects manifest quite differently for in silico 3C and microscopy. Our results show that looping interactions that do not directly involve an enhancer-promoter pair can nevertheless significantly modulate their interactions. This phenomenon is analogous to allosteric regulation in proteins, where a conformational change triggered by binding of a regulatory molecule to one site affects the state of another site.
Superposition of molecular structures using quaternions

Abstract An algorithm is developed that finds the optimal orientation of a rigid molecular structure, represented by N reference sites, with respect to the same number of sites in an observed structure. The optimal orientation is found by minimizing the weighted sum of squared deviations of the rotated reference site positions from the observed site positions. The rotation is parametrized by a quaternion whose components, written as a column vector, are shown to be an eigenvector of a characteristic matrix which is defined in terms of the coordinate sets to be superimposed. The presented algorithm is particularly useful with respect to the calculation of orientational correlations of molecular structures.
The First Stars: A Low-Mass Formation Mode

We perform numerical simulations of the growth of a Population III stellar system under photodissociating feedback. We start from cosmological initial conditions at z = 100, self-consistently following the formation of a minihalo at z = 15 and the subsequent collapse of its central gas to high densities. The simulations resolve scales as small as approx. 1 AU, corresponding to gas densities of 10(exp 16)/cu cm. Using sink particles to represent the growing protostars, we evolve the stellar system for the next 5000 yr. We find that this emerging stellar group accretes at an unusually low rate compared with minihalos which form at earlier times (z = 20-30), or with lower baryonic angular momentum. The stars in this unusual system will likely reach masses ranging from <1Stellar Mass to approx. 5 Stellar Mass by the end of their main-sequence lifetimes, placing them in the mass range for which stars will undergo an asymptotic giant branch (AGB) phase. Based upon the simulation, we predict the rare existence of Population III stars that have survived to the present day and have been enriched by mass overflow from a previous AGB companion.
Further Evidence on the Extent and Origins of JIT's Profitability Effects

Empirical research provides scant evidence that just‐in‐time (JIT) adopters outperform their non‐adopting industry peers. Using a sample of 201 JIT adopters and matched non‐adopters, we examine the relation between financial performance and JIT. Our sample‐wide results indicate that JIT adopters improve financial performance relative to non‐adopters, and that profit margin, rather than asset turnover, is the primary source of such improvement. However, results of additional analyses suggest that JIT adopters below a firm‐size threshold do not improve financial performance, a finding that reconciles our study to Balakrishnan et al. (1996), which examined a JIT adopter sample that included a greater proportion of small firms.
Iron Fluorescence from within the Innermost Stable Orbit of Black Hole Accretion Disks

The fluorescent iron Kα line is a powerful observational probe of the inner regions of black hole accretion disks. Previous studies have assumed that only material outside the radius of marginal stability (r = 6m for a Schwarzschild hole) can contribute to the observed line emission. Here we show that fluorescence by material inside the radius of marginal stability, which is in the process of spiraling toward the event horizon, can have an observable influence on the iron line profile and equivalent width. For concreteness, we consider the case of a geometrically thin accretion disk, around a Schwarzschild black hole, in which fluorescence is excited by an X-ray source placed at some height above the disk and on the axis of the disk. Fully relativistic line profiles are presented for various source heights and efficiencies. It is found that the extra line flux generally emerges in the extreme red wing of the iron line, because of the large gravitational redshift experienced by photons from the region within the radius of marginal stability. We apply our models to the variable iron line seen in the ASCA spectrum of the Seyfert nucleus MCG -6-30-15. It is found that the change in the line profile, equivalent width, and continuum normalization can be well explained as being due to a change in the height of the source above the disk. Thus, we can explain the iron line properties of MCG -6-30-15 within the context of an accretion disk around a nonrotating black hole. This contrasts with previous studies that, due to the absence of fluorescence from within the radius of marginal stability, have indicated that this object possesses a rapidly rotating (i.e., near-extremal Kerr) black hole. This is an important issue since it has a direct bearing on the spin paradigm for the radio-loud/radio-quiet dichotomy seen in accreting black hole systems. We discuss some future observational tests that could help distinguish slowly rotating black holes from rapidly rotating holes.
Axiomatic design of mechanical systems

Design is done in many fields. Although the design practices in different fields appear to be distinct from each other, all fields use a common thought process and design principles. Consequently, the true differences between these fields are minor, often consisting of the definitions of words, the specific data, and knowledge. In comparison, larger differences can exist within a given field between simple systems and large systems due to the size and the time dependent nature of functional requirements. The axiomatic approach to design provides a general theoretical framework for all these design fields, including mechanical design. The key concepts of axiomatic design are : the existence of domains, the characteristic vectors within the domains that can be decomposed into hierarchies through zigzagging between the domains, and the design axioms (i.e., the Independence Axiom and the Information Axiom). Based on the two design axioms, corollaries and theorems can be stated or derived for simple systems, large systems, and organizations. These theorems and corollaries can be used as design rules or guidelines for designers. The basic concepts are illustrated using simple mechanical design examples. When design is viewed axiomatically, not only product design but all other designs, including design of process, systems, software, organizations, and materials, are amenable to systematic treatment.
A General and Convenient Preparation of [Bis(trifluoroacetoxy)iodo]perfluoroalkanes and [Bis(trifluoroacetoxy)iodo]arenes by Oxidation of Organic Iodides Using Oxone and Trifluoroacetic Acid

[Bis(trifluoroacetoxy)iodo]perfluoroalkanes CnF2n+1I(OCOCF3)2 (n = 4, 6, 8, 10, 12) can be conveniently prepared by the oxidation of the corresponding perfluoroalkyl iodides with Oxone in trifluoroacetic acid at room temperature and subsequently converted to the stable [hydroxy(tosyloxy)iodo]perfluoroalkanes, CnF2n+1I(OH)OTs, by treatment with p-toluenesulfonic acid. This general and convenient procedure has been further extended to the synthesis of various [bis(trifluoroacetoxy)iodo]arenes, ArI(OCOCF3)2.
Sensitivity considerations in a multiple-feedback universal active filter

A multiple-feedback universal active filter is presented and evaluated on the basis of its sensitivity performance. This canonic realization provides, simultaneously, second-order low-pass, bandpass, and highpass outputs that may be combined to implement generalized biquadratic transfer functions. Additionally, it features the capability of local positive feedback to allow Q -enhancement with the ensuing advantages of sensitivity minimization and reduction in RC -element spread. A new analysis technique is developed for the evaluation of \omega_0 and Q sensitivities to operational-amplifier (OA) dc gain and gain-bandwidth product. This technique is extended to modify the figure of merit, introduced for sensitivity minimization purposes by Fleischer, and thus leads to easily obtainable expressions for optimum Q -enhancement factor and the corresponding value of Q in the absence of positive feedback. Making use of this sensitivity analysis technique, the new design is compared to two other high- Q filter configurations widely known for their excellent sensitivity characteristics. It is concluded that the new filter exhibits comparable performance especially in higher tolerance applications using wide-bandwidth OA's.
Offshoring under Oligopoly

This paper uncovers a novel pattern of offshoring and market structure in a high- tech industry, and proposes a simple oligopoly model to explain it. Specically, the hard disk drive industry (1976�98) witnessed massive waves of entry, exit, and the relocation of manufacturing plants to low-cost countries, in which shakeouts occurred predominantly among homerms and almost all survivors were offshorerms. I build and estimate a dynamic offshoring game with entry/exit to explain these facts, and then investigate the relationship between offshoring and market structure as well as the impacts of hypothetical government interventions.
On diagrammatic bounds of knot volumes and spectral invariants

In recent years, several families of hyperbolic knots have been shown to have both volume and �1 (first eigenvalue of the Laplacian) bounded in terms of the twist number of a diagram, while other families of knots have volume bounded by a generalized twist number. We show that for general knots, neither the twist number nor the generalized twist number of a diagram can provide two-sided bounds on either the volume or �1. We do so by studying the geometry of a family of hyperbolic knots that we call double coil knots, and finding two-sided bounds in terms of the knot diagrams on both the volume and on �1. We also extend a result of Lackenby to show that a collection of double coil knot complements forms an expanding family iff their volume is bounded. the volume of a closed 3-braid is bounded above and below in terms of the generalized twist number of the braid. More recently, Lackenby showed that for alternating and highly twisted knots, the first eigenvalue λ1 of the Laplacian can be estimated in terms of the twist number (18). Based on these examples, one might hope that a suitable generalization of the twist number of a diagram controls the geometry of all hyperbolic knot complements. In this paper, we show that the twisting in a diagram cannot give two-sided geometric bounds for general knots. We do so by presenting a class of knots, called double coil knots, for which the volume can be made bounded while the twist number becomes arbitrarily large, or the volume can be made unbounded while the generalized twist number stays constant. Similarly, we show that λ1 can stay bounded while the twist number becomes arbitrarily large, or λ1 can approach 0 while the generalized twist number stays constant. To state our results more precisely, we need a few definitions.
Discrete-time chaotic-map truly random number generators: design, implementation, and variability analysis of the zigzag map

In this paper, we introduce a novel discrete chaotic map named zigzag map that demonstrates excellent chaotic behaviors and can be utilized in truly random number generators (TRNGs). We comprehensively investigate the map and explore its critical chaotic characteristics and parameters. We further present two circuit implementations for the zigzag map based on the switched current technique as well as the current-mode affine interpolation of the breakpoints. In practice, implementation variations can deteriorate the quality of the output sequence as a result of variation of the chaotic map parameters. In order to quantify the impact of variations on the map performance, we model the variations using a combination of theoretical analysis and Monte-Carlo simulations on the circuits. We demonstrate that even in the presence of the map variations, a TRNG based on the zigzag map passes all of the NIST 800-22 statistical randomness tests using simple post processing of the output data.
Recent Development of Regio- and Stereoselective Aminohalogenation Reaction of Alkenes

This microreview presents the development of the catalytic aminohalogenation of olefins. The olefin substrates include electron-deficient and functionalized ones, such as α,β-unsaturated esters, α,β-unsaturated ketones and α,β-unsaturated nitriles. In addition, the first asymmetric aminohalogenation by the use of Evans chiral auxiliaries is also discussed. The convincing evidence is provided to support the aziridinium mechanism of aminohalogenation reaction. The applications of this reaction are described by converting vicinal haloamines into other important synthetic building blocks. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
An Institutional Analysis of Vertical Coordination verses Vertical Integration: The Case of the US Broiler Industry

This paper analyzes the situation, structure and performance of broiler production. The inherent interdependence in broiler production is high transactions costs. Two types of transactions costs, asset specificity with uncertainty and high information costs, are identified and explored. The performances of the alternative structures, vertical integration and vertical coordination, are outlined. In broiler production, vertical coordination is preferred by both firms and growers because it minimizes transactions costs. These conclusions are extended to other agricultural commodities, using pork and rice as examples. 13 pages.
Planetary Radii across Five Orders of Magnitude in Mass and Stellar Insolation: Application to Transits

Toaidinthephysicalinterpretationofplanetaryradii constrainedthroughobservationsoftransitingplanets,oreventuallydirectdetections,wecomputemodelradiiofpurehydrogen-helium,water,rock,andironplanets,alongwithvarious mixtures. Masses ranging from 0.01 Earth masses to 10 Jupiter masses at orbital distances of 0.02–10 AU are considered. For hydrogen-helium rich planets, our models are the first to couple planetary evolution to stellar irradiation over a wide range of orbital separations (0.02–10 AU) through a nongray radiative-convective equilibrium atmosphere model. Stellar irradiation retards the contraction of giant planets, but its effect is not a simple function of theirradiationlevel:aplanetat1AUcontractsasslowlyasaplanetat0.1AU.WeconfirmtheassertionofGuillotthat very old giant planets under modest stellar irradiation (like that received by Jupiter and Saturn) develop isothermal atmospheric radiative zones once the planet’s intrinsic flux drops to a small fraction of the incident flux. For hydrogenhelium planets, we consider cores up to 90% of the total planet mass, comparable to those of Uranus and Neptune. If ‘‘hot Neptunes’’ have maintained their original masses and are not remnants of more massive planets, radii of � 0.30– 0.45RJ areexpected.Waterplanetsare � 40%–50%largerthanrockyplanets,independentofmass.Finally,weprovide tables of planetary radii at various ages and compositions, and for ice-rock-iron planets we fit our results to analytic functions, which will allow for quick composition estimates, given masses and radii, or mass estimates, given only planetary radii. These results will assist in the interpretation of observations for both the current transiting planet surveys as well as upcoming space missions, including COROT and Kepler.
Clustering with qualitative information

We consider the problem of clustering a collection of elements based on pairwise judgments of similarity and dissimilarity. Bansal et al. (in: Proceedings of 43rd FOCS, 2002, pp. 238-247) cast the problem thus: given a graph G whose edges are labeled ''+'' (similar) or ''-'' (dissimilar), partition the vertices into clusters so that the number of pairs correctly (resp., incorrectly) classified with respect to the input labeling is maximized (resp., minimized). It is worthwhile studying both complete graphs, in which every edge is labeled, and general graphs, in which some input edges might not have labels. We answer several questions left open by Bansal et al. (2002) and provide a sound overview of clustering with qualitative information. Specifically, we demonstrate a factor 4 approximation for minimization on complete graphs, and a factor O(logn) approximation for general graphs. For the maximization version, a PTAS for complete graphs was shown by Bansal et al. (2002), we give a factor 0.7664 approximation for general graphs, noting that a PTAS is unlikely by proving APX-hardness. We also prove the APX-hardness of minimization on complete graphs.
The absolute stereochemistry of Kahalalide F

Abstract Kahalalide F ( 1 ) is a depsipeptide of 14 residues, five of which form a 19-membered ring. It was isolated from a marine mollusk, Elysia rufescens , and is currently in preclinical trials against lung and colon cancers. It was known from conventional amino acid analysis that five valine and two threonine residues represented D- and L- enantiomers, but their position in the molecule was not known. After extensive hydrolytic trials, a combination of acid hydrolysis and hydrazinolysis succeeded in definitive stereochemical assignment.
Retrieved Products from Simulated Hyperspectral Observations of a Hurricane

Retrievals were run using the AIRS Science Team Version-6 AIRS Only retrieval algorithm, which generates a Neural-Net first guess (T(sub s))(sup 0), (T(p))(sup 0), and (q(p))(sup 0) as a function of observed AIRS radiances. AIRS Science Team Neural-Net coefficients performed very well beneath 300 mb using the simulated radiances. This means the simulated radiances are very realistic. First guess and retrieved values of T(p) above 300 mb were biased cold, but both represented the model spatial structure very well. QC'd T(p) and q(p) retrievals for all experiments had similar accuracies compared to their own truth fields, and were roughly consistent with results obtained using real data. Spatial coverage of retrievals, as well as the representativeness of the spatial structure of the storm, improved dramatically with decreasing size of the instrument's FOV. We sent QC'd values of T(p) and q(p) to Bob Atlas at AOML for use as input to OSSE Data Assimilation experiments.
Force Regulation in Multiple Manipulator Systems

An important advantage of multiple manipulator systems is the possibility to regulate the internal force in the payload. Common force control strategies include impedance control, position accommodation force control and Jacobian force control. This paper mainly considers the latter two schemes for which detailed dynamic models for the arms and the environment are not required. Comparison between these two methods are made and some experimental results on decentralized position accommodation force control are discussed.
On energy-efficient hierarchical cross-layer design: joint power control and routing for ad hoc networks

A hierarchical cross-layer design approach is proposed to increase energy efficiency in ad hoc networks through joint adaptation of nodes' transmitting powers and route selection. The designmaintains the advantages of the classic OSI model, while accounting for the cross-coupling between layers, through information sharing. The proposed joint power control and routing algorithm is shown to increase significantly the overall energy efficiency of the network, at the expense of a moderate increase in complexity. Performance enhancement of the joint design using multiuser detection is also investigated, and it is shown that the use of multiuser detection can increase the capacity of the ad hoc network significantly for a given level of energy consumption.
Waiting Time Distribution for the Emergence of Superpatterns

Consider a sequence \(\{X_{n}\}_{n=1}^{\infty }\) of i.i.d. uniform random variables taking values in the alphabet set {1, 2,…, d}. A k-superpattern is a realization of \(\{X_{n}\}_{n=1}^{t}\) that contains, as an embedded subsequence, each of the non-order-isomorphic subpatterns of length k. We focus on the (non-trivial) case of d = k = 3 and study the waiting time distribution of \(\tau =\inf \{t\ge 1:\{X_{n}\}_{n=1}^{t}\ \text {is\ a\ superpattern}\}\). Our restricted set-up leads to proofs that are very combinatorial in nature, since we are essentially conducting a string analysis.
Multiterminal source coding with an entropy-based distortion measure

In this paper, we consider a class of multiterminal source coding problems, each subject to distortion constraints computed using a specific, entropy-based, distortion measure. We provide the achievable rate distortion region for two cases and, in so doing, we demonstrate a relationship between the lossy multiterminal source coding problems with our specific distortion measure and (1) the canonical Slepian-Wolf lossless distributed source coding network, and (2) the Ahlswede-Korner-Wyner source coding with side information problem in which only one of the sources is recovered losslessly.
An event-related potential investigation of error monitoring in adults with a history of psychosis.

Abstract Objective Previous research suggests that deficits in error monitoring contribute to psychosis and poor functioning. Consistent with the NIMH Research Domain Criteria initiative, this study examined electrophysiological brain activity, appraisal of self-performance, and personality traits related to psychosis during error monitoring in individuals with and without a history of psychosis across disorders. Methods Error-related negativity (ERN), correct response negativity (CRN), error positivity (Pe), and correct response positivity (Pc) were recorded in 14 individuals with a history of psychosis (PSY) and 12 individuals with no history of psychosis (CTR) during a flanker task. Participants continuously rated their performance and completed the Schizotypal Personality Questionnaire-Brief Revised (SPQ-BR). Results Compared with CTR, PSY exhibited reduced ERN and Pe amplitudes and was also less accurate at evaluating their performance. Group differences were specific to error trials. Across all participants, smaller Pe amplitudes were associated with greater scores on the SPQ-BR Cognitive-Perceptual factor and less accuracy in subjective identification of errors. Conclusions Individuals with a history of psychosis, regardless of diagnosis, demonstrated abnormal neural activity and imprecise confidence in response during error monitoring. Significance Results suggest that disruptions in neural circuitry may underlie specific clinical symptoms across diagnostic categories.
Characterization of solid liquid suspensions utilizing ultrasonic measurements

Rapid, online, noninvasive measurements of the particle size and concentration of moderate to highly concentrated slurries is required for the efficient process measurement and control for many processes. High concentrations are often found in government applications such as waste remediation for the Department of Energy sites and in industrial applications such as chemical and pharmaceutical manufacturing. However, existing methods based on ultrasonic attenuation can become inaccurate for nondilute suspensions due to the complex interactions of ultrasonic waves with the constituents of the slurries. Further complications arise because of the necessity for careful transducer alignment. We are developing two measurements that help to overcome these difficulties, the ultrasonic backscattering and measurements of the diffuse field properties. The backscattering measurement is attractive because viscous, thermal, and inertial effects have small contributions to backscattering. Furthermore, the backscattering theories are simpler than attenuation theories and lend themselves to more stable inversion process. In addition, the measurements of backscattering and diffuse fields do not require long travel distances and can be performed with a single transducer thus eliminating alignment problems. We will present ultrasonic measurements on solid liquid suspensions designed to elucidate the particle size and concentration at high concentrations.
Existence of periodic motions of a tether trailing satellite

Tethered satellite systems are becoming more widely used in space explorations. In this analytical study, the dynamics of a satellite trailing a tether are addressed. More precisely, we derive the conditions for existence of periodic motions about the relative equilibrium states of the tethered system. The system is considered to be affected by the atmospheric drag and nonspherical Earth. The mathematical proof of the existence result is based on the Leray-Schauder degree theory. Main conclusions can be easily generalized for any bounded forcing and/or forces with linear growth.
Two Mars years of clouds detected by the Mars Orbiter Laser Altimeter

[1] The Mars Orbiter Laser Altimeter (MOLA) instrument operated as an atmospheric lidar system as well as an altimeter, detecting absorptive clouds in northern latitudes shortly after orbit insertion in October 1997 and reflective clouds over the north polar cap at the start of the Science Phasing Orbits in March 1998. Global cloud measurements commenced with the primary mapping mission in March 1999, with nearly continuous coverage for 1.25 Mars years. MOLA tracked several dust storms, culminating with a major dust storm in June 2001. Reflective clouds, exhibiting distinctive patterns governed by insolation and the dynamics of the atmosphere, were detected at elevations up to 20 km above the surface, chiefly in the polar winter night. MOLA distinguishes cloud returns by pulse width and energy measurements. Unusually strong and brief reflections with minimal extinction suggest precipitation of CO2 snow under supercooled conditions. Weaker cloud reflections occurred at all latitudes. Some reflective daylight clouds at low latitudes suggested convective vortices or “dust devils.” Ground fogs composed of dust and H2O ice formed at night along the seasonal frost line. Absorptive clouds, while not resolved altimetrically, tracked the advancing and receding edges of the seasonal polar caps. The absorptive and reflective clouds provide a seasonal profile of atmospheric activity spanning two Martian years. Winter reflective cloud activity declined to background levels earlier in the second year at both poles, suggesting interannual warming.
The Effect of Risk and Autonomy on Independent Hog Producers’ Contracting Decisions

The introduction of vertical coordination in the hog industry has provided producers with new business arrangements for raising hogs. While some researchers have elicited utility functions for hog producers on the basis of income risk, none have addressed autonomy, a factor which appears to be important in business arrangement selection for independent family hog operations. In this study, a method is developed for eliciting a multi-attribute function with attributes of income and autonomy. Utility functions are elicited for a group of Minnesota farrow-to-finish hog producers. For these producers, autonomy dominated risk as the most important attribute in business arrangement selection.
Industrial Policy and Downstream Export Performance

Industrial policies ( IPs) are commonly used by countries to promote targeted sectors but may have significant impacts on downstream sectors. Using a new hand-collected database of steel-sector IP use in major steel-producing countries, I find that IP use is quite harmful to downstream sectors. A 1 standard deviation increase in steel IP presence leads to a 1.2% decline in export competitiveness for the average downstream manufacturing sector in the first few years of its application, and a 6% decline for downstream sectors that use steel most intensively. These results are largely driven by the less-developed countries in my sample. [ABSTRACT FROM AUTHOR]
Lepton Acceleration by Relativistic Collisionless Magnetic Reconnection

We have calculated self-consistent equilibria of a collisionless relativistic electron-positron gas in the vicinity of a magnetic X-point. For the considered conditions, pertinent to extragalactic jets, we find that leptons are accelerated up to Lorentz factors Γ0 = κeB0L2/mc2 1, where B0 is the typical magnetic field strength, ≡ E0/B0, with E0 the reconnection electric field, L is the length scale of the magnetic field, and κ ≈ 12. The acceleration is due to the dominance of the electric field over the magnetic field in a region around the X-point. The distribution function of the accelerated leptons is found to be approximately dn/dγ ∝ γ-1 for γ Γ0. The apparent distribution function may be steeper than γ-1 due to the distribution of Γ0 values and/or the radiative losses. Self-consistent equilibria are found only for plasma inflow rates to the X-point less than a critical value.
The impact of high school financial education : experimental evidence from Brazil

This paper studies the impact of a comprehensive financial education program spanning six states, 868 schools, and approximately 20,000 high school students in Brazil through a randomized control trial. The program increased student financial knowledge by a quarter of a standard deviation and led to a 1.4 percentage point increase in saving for purchases, better likelihood of financial planning, and greater participation in household financial decisions by students. "Trickle-up" impacts on parents were also significant, with improvements in parent financial knowledge, savings, and spending behavior. The study also finds evidence that the program affected students' inter-temporal preferences and attitudes.
An implanted-emitter 4H-SiC bipolar transistor with high current gain

An epi-base, implanted-emitter, npn bipolar transistor which showed a maximum common emitter current gain (/spl beta/) of /spl sim/40, the highest current gain reported for BJT in any polytype of SiC has been experimentally demonstrated in 4H-SiC. The forward drop was /spl sim/1 V at forward current density of 50 A/cm/sup 2/. The current gain decreases hence specific on-resistance increases with increasing temperature. The negative temperature coefficient of /spl beta/ makes the device attractive for paralleling and for preventing thermal runaways.
Gas phase studies of the competition between substitution and elimination reactions

Gas phase studies allow for the examination of organic reaction mechanisms in the absence of solvation effects and therefore probe the intrinsic reactivity of the reaction partners. The competition between substitution and elimination reactions has been a topic of interest for decades, but it has been difficult to examine in the gas phase because both pathways generally lead to the same ionic product and cannot be distinguished by mass spectrometry. By using dianions as nucleophiles, the reactions produce two ionic products, one of which identifies the mechanism. With this approach, we have examined a variety of substituent effects on the gas phase competition between substitution and elimination. In addition, we have found that similar processes occur during collisional activation of salt complexes that contain a dianion and a tetraalkylammonium cation. Overall, the results show that the gas phase studies probe the same fundamental features found in the condensed phase and provide valuable insights into reaction mechanisms.
Collimated blue and infrared beams generated by two-photon excitation in Rb vapor

Utilizing two-photon excitation in hot Rb vapor we demonstrate the generation of collimated optical fields at 420 and 1324 nm. Input laser beams at 780 and 776 nm enter a heated Rb vapor cell collinear and circularly polarized, driving Rb atoms to the 5D5/2 state. Under phase-matching conditions coherence among the 5S1/2→5P3/2→5D5/2→6P3/2 transitions produces a blue (420 nm) beam by four-wave mixing. We also observe a forward and backward propagating IR (1324 nm) beam, due to cascading decays through the 6S1/2→5P1/2 states. Power saturation of the generated beams is investigated by scaling the input powers to greater than 200 mW, resulting in a coherent blue beam of 9.1 mW power, almost an order of magnitude larger than previously achieved. We measure the dependences of both beams in relation to the Rb density, the frequency detuning between Rb ground-state hyperfine levels, and the input laser intensities.
Cold-based mountain glaciers on Mars: Western Arsia Mons

Surface environmental conditions on Mars are currently extremely cold and hyperarid, most equivalent to polar deserts on Earth. Coupling newly acquired Mars data with fieldbased observations regarding the flow, surface morphology, and depositional history of polar glaciers in Antarctica, we show that the multiple facies of an extensive fan-shaped deposit on the western flanks of Arsia Mons volcano are consistent with deposition from cold-based mountain glaciers. An outer ridged facies that consists of multiple laterally extensive, arcuate and parallel ridges, resting without disturbance on both well-preserved lava flows and an impact crater, is interpreted as drop moraines formed at the margin of an ablating and predominantly receding cold-based glacier. A knobby facies that consists of equidimensional knobs, each to several kilometers in diameter, is inward of the ridges; this facies is interpreted as a sublimation till derived from in situ downwasting of ashrich glacier ice. A third facies comprising distinctive convex-outward lobes with concentric parallel ridges and aspect ratios elongated downslope likely represents rock-glacier deposits, some of which may still be underlain by a core of glacier ice. Taken together, these surficial deposits show that the western flank of Arsia Mons was occupied by an extensive mountain glacial system accumulating on, and emerging from, the upper slopes of the volcano and spreading downslope to form a piedmont-like fan.
Tracing Galaxy Assembly: Tadpole Galaxies in the Hubble Ultra Deep Field

In the Hubble Ultra Deep Field (HUDF) an abundance of galaxies is seen with a knot at one end plus an extended tail, resembling a tadpole. These "tadpole galaxies" appear dynamically unrelaxed—presumably in an early merging stage—where tidal interactions likely created the distorted knot-plus-tail morphology. Here we systematically select tadpole galaxies from the HUDF and study their properties as a function of their photometric redshifts. In a companion HUDF variability study presented in this issue, Cohen et al. revealed a total of 45 variable objects believed to be active galactic nuclei (AGNs). Here we show that this faint AGN sample has no overlap with the tadpole galaxy sample, as predicted by recent theoretical work. The tadpole morphology—combined with the lack of overlap with the variable objects—supports the idea that these galaxies are in the process of an early-stage merger event, i.e., at a stage that likely precedes the "turn-on" of any AGN component and the onset of any point-source variability. We show that the redshift distribution of tadpole galaxies follows that of the general field galaxy population, indicating that—if most of the tadpole galaxies are indeed dynamically young—the process of galaxy assembly generally kept up with the reservoir of available field galaxies as a function of cosmic epoch. These new observational results highlight the importance of merger-driven processes throughout cosmic history and are consistent with a variety of theoretical and numerical predictions.
The thermal rearrangement of 7,7-dimethylbicyclo[3.2.0]hept-2-ene

Abstract The title compound, when subjected to gas-phase pyrolysis at 275°C, undergoes predominantly fragmentation to cyclopentadiene and isobutylene.
Wars and Child Health: Evidence from the Eritrean-Ethiopian Conflict

Conflict between and within countries can have lasting health and economic consequences, but identifying such effects can be empirically challenging. This paper uses household survey data from Eritrea to estimate the effect of exposure to the 1998-2000 Eritrea-Ethiopia war on children’s health. The identification strategy exploits exogenous variation in the conflict’s geographic extent and timing and the exposure of different birth cohorts to the fighting. The unique survey data include details on each household’s migration history, which allows us to measure a child’s geographic location during the war and without which war exposure would be incorrectly classified. War-exposed children have lower height-for-age Z-scores, with similar effects for children born before or during the war. Both boys and girls who are born during the war experience negative impacts due to conflict. Effects are robust to including region-specific time trends, alternative conflict exposure measures, and mother fixed effects.
The sorbicillinoid family of natural products: isolation, biosynthesis, and synthetic studies.

Covering: 1948 up to the end of 2010 The sorbicillinoids are a family of hexaketide metabolites that have been isolated from a variety of fungal sources, collected from both marine and terrestrial sources. Since 1948, the family has grown in size to include over 50 members, many of which have complex, highly oxygenated, bicyclic and tricyclic frameworks. In conjunction with their biological activity, the structural complexity of these structures has inspired several synthetic campaigns and has also led to controversy surrounding the biosynthetic pathway responsible for the natural production of these compounds. Through this review, we aim to give a historical perspective to each of these areas and hope to inspire new avenues of research for addressing the knowledge gaps that still exist.
Topological phenomena in quantum walks: elementary introduction to the physics of topological phases

Discrete quantum walks are dynamical protocols for controlling a single quantum particle. Despite of its simplicity, quantum walks display rich topological phenomena and provide one of the simplest systems to study and understand topological phases. In this article, we review the physics of discrete quantum walks in one and two dimensions in light of topological phenomena and provide elementary explanations of topological phases and their physical consequence, namely the existence of boundary states. We demonstrate that quantum walks are versatile systems that simulate many topological phases whose classifications are known for static Hamiltonians. Furthermore, topological phenomena appearing in quantum walks go beyond what has been known in static systems; there are phenomena unique to quantum walks, being an example of periodically driven systems, that do not exist in static systems. Thus the quantum walks not only provide a powerful tool as a quantum simulator for static topological phases but also give unique opportunity to study topological phenomena in driven systems.
The perception of tactile distance: influences of body site, space, and time

Vibrotactile prostheses for deaf or blind persons have been applied to any number of different locations on the body, including the finger, wrist, forearm, abdomen, back, and nape of the neck. The discriminability of patterns presented by such devices can be affected by the acuity of the site of application and the resolution of the display. In addition, the mutual influences among stimuli close together in both space and time can affect percepts within a broad range of parameters. For example, consideration must be given to a variety of tactile illusions often associated with the spatial separations and the range of temporal intervals typically used in cutaneous communication displays. Experiments are reported in which magnitude estimates and cross-modality matches of perceived extent produced by pairs of vibrotactile taps presented to separate loci were obtained on three different body sites. Perceived distance was directly related both to the timing between the taps and to their physical separation. The findings show a consistent relationship to cortical magnification across body sites.
Estimating maximum sustainable injection pressure during geological sequestration of CO2 using coupled fluid flow and geomechanical fault-slip analysis

This paper demonstrates the use of coupled fluid flow andgeomechanical fault slip (fault reactivation) analysis to estimate themaximum sustainable injection pressure during geological sequestration ofCO2. Two numerical modeling approaches for analyzing faultslip areapplied, one using continuum stress-strain analysis and the other usingdiscrete fault analysis. The results of these two approaches to numericalfault-slip analyses are compared to the results of a more conventionalanalytical fault-slip analysis that assumes simplified reservoirgeometry. It is shown that the simplified analytical fault-slip analysismay lead to either overestimation or underestimation of the maximumsustainable injection pressure because it cannot resolve importantgeometrical factors associated with the injection induced spatialevolution of fluid pressure and stress. We conclude that a fully couplednumerical analysis can more accurately account for the spatial evolutionof both insitu stresses and fluid pressure, and therefore results in amore accurate estimation of the maximum sustainable CO2 injectionpressure.
Incentive compatible reforms : the political economy of public investments in Mongolia

Why do politicians distort public investments? And given that public investments are poor because presumably that is what is politically rational, what types of reforms are likely to be both efficiency improving and compatible with the interests of politicians? This paper explores these two questions in the context of Mongolia. It argues that Mongolian members of parliament have an incentive to over-spend on smaller projects that bring benefits to specific geographical localities and to under-spend on large infrastructure that would bring economic benefits to Mongolia on the whole. The incentive for the former is that members of parliament internalize the political benefits from the provision of particular, targeted benefits to specific communities. The disincentive for the latter is that large infrastructure carries a political risk because the political faction in control of that particular ministry would have access to huge rents and become politically too powerful. The identity of these "winners" is uncertain ex ante, given the relatively egalitarian and ethnically homogenous nature of Mongolia's society and polity. Anticipating this risk, members of parliament are reluctant to fund these projects. Since these large infrastructure projects are crucial for national growth, neglecting them hurts all members of parliament. Members of parliament will therefore support reforms that collectively tie their hands by safeguarding large, strategic investment projects from political interference thereby ensuring that no political faction becomes too powerful. This protection of mega-projects would need to be part of a bargain that also allows geographical targeting of some percentage of the capital budget.
Tail Dependence among Agricultural Insurance Indices: The Case of Iowa County-Level Rainfalls

Index insurance has been promoted as a cost-effective risk management alternative for agricultural producers in developing countries. In this paper, we ask whether spatially separated weather variables commonly used in index insurance design, such as rainfall at different weather stations within a defined geographical area, are more highly correlated at the tails. As a case study, we assess the degree of tail dependence exhibited by Iowa June county-level rainfalls using copulas. We search among various candidate bivariate copulas and, using goodness-of-fit for copulas, attempt to identify the copula structures that best explain the nature of dependence among rainfalls in adjacent counties. Our results provide strong evidence that lower tail dependence exists in most of adjacent county-level rainfalls in Iowa. The results also suggest that patterns of tail dependence differ across counties.