cssi/SciSciGPT-SciSciNet huggingface dataset:
Integrated design of an adaptive neurocontroller for a 2-D aeroelastic system

The design of control configured structures has been considered in a number of recent studies. Both active and passive measures for structural vibration control have been examined in this context. The present paper addresses issues related to the use of neural network based control systems in such applications. A simplified 2-D representation of an aeroelastic system, consisting of an airfoil with a trailing-edge flap, comprises the test bed for the present study. With a proper selection of structural spring characteristics, and choice of unsteady aerodynamic forces and moments, the system provides a rudimentary 2-D model of a helicopter rotor blade that includes both structural and aerodynamic nonlinearities. The integrated optimal desisgn of the plant and its control system for optimized response under disturbance loading is the principle objective of the design exercise. The focus of the paper is three-fold — it establishes the justifiction for replacing traditional control systems with neurocontrollers in such problems, examines issues related to an integrated structural-control design strategy, and discusses a detailed implementation of the approach in a linearized 2-D aeroelastic system. The design problem contains multiple relative optima, and the use of a genetic algorithm (GA) based optimization procedure is shown to be an effective tool to locate the optimal design. Results from numerical experiments are presented in support of the proposed design approach.
Designing and managing an SNA network for growth

The IBM Information Network is a nationwide System Network Architecture (SNA) network that offers network services and application offerings to end users. This paper describes the techniques used to design and manage the growth of the network. Emphasis is placed on the design process and the migration and implementation plans to expand the network while still providing 24-hour operation 7 days a week. Areas covered include adding processors, bandwidth, multiplexers, and end user devices.
Two-color-laser-driven direct electron acceleration in infinite vacuum

We propose a scheme that uses a two-color pulsed radially-polarized laser beam to achieve electron acceleration exceeding 90% of the theoretical energy gain limit, over twice of what is possible with a one-color beam.
EdgeCS: edge guided compressive sensing reconstruction

Compressive sensing (CS) reconstructs images from a small number of projections. We propose EdgeCS - edge guided CS reconstruction - to recover images of higher qualities from fewer measurements than the current state-of-the-art methods. Accurate edge information can significantly improve image recovery quality and speed, but such information is encoded in the CS measurements of an image. To take advantage of edge information in CS recovery, EdgeCS alternatively performs CS reconstruction and edge detection in a way that each benefits from the latest solution of the other. EdgeCS is fast and returns high-quality images. It exactly recovers the 256 × 256 Shepp-Logan phantom from merely 7 radial lines (or 3.03% k-space), which is impossible for most existing algorithms. It accurately reconstructs a 512 × 512 magnetic resonance image from 21% noisy samples. Moreover, it is also able to reconstruct complex-valued images. Each took about 30 seconds on an ordinary laptop. The algorithm can be easily ported to GPUs for a speedup of more than 10 folds.
Tracking the earth satellite and data transmission by radio

The next round of problems created by an earth satellite after it is placed in its orbit are those associated with proving that the satellite is in fact orbiting, and the measurement of its orbit. The magnitude of these problems for optical methods are discussed, and the Minitrack system developed by the Naval Research laboratory for acquisition and tracking of the satellite by radio techniques is described. A sub-miniature radio transmitter operating continuously for at least two weeks will be provided within the satellite to illuminate antennas at ground tracking stations. By phase-comparison techniques, these ground stations will measure the angular position of the satellite as it passes through the antenna beam, recording its "signature" automatically without the need for initial tracking information. Analysis of this signature will provide the complete angular history of the satellite passage in the form of direction cosines and time. These data will be transmitted immediately to a central computing facility for the computation and publication of ephemerides. Specific ephemerides will be transmitted to each principal optical tracking station to provide acquisition data to them. The probable tracking accuracies and the major problems associated with the Minitrack System are described.
Phase transitions and backbones of the asymmetric traveling salesman problem

In recent years, there has been much interest in phase transitions of combinatorial problems. Phase transitions have been successfully used to analyze combinatorial optimization problems, characterize their typical-case features and locate the hardest problem instances. In this paper, we study phase transitions of the asymmetric Traveling Salesman Problem (ATSP), an NP-hard combinatorial optimization problem that has many real-world applications. Using random instances of up to 1,500 cities in which intercity distances are uniformly distributed, we empirically show that many properties of the problem, including the optimal tour cost and backbone size, experience sharp transitions as the precision of intercity distances increases across a critical value. Our experimental results on the costs of the ATSP tours and assignment problem agree with the theoretical result that the asymptotic cost of assignment problem is π26 as the number of cities goes to infinity. In addition, we show that the average computational cost of the well-known branch-and-bound subtour elimination algorithm for the problem also exhibits a thrashing behavior, transitioning from easy to difficult as the distance precision increases. These results answer positively an open question regarding the existence of phase transitions in the ATSP, and provide guidance on how difficult ATSP problem instances should be generated.
Seasonal variations of atmospheric electricity measured at Amundsen‐Scott South Pole Station

[1] Recent studies have shown that the general understanding of the Earth's global circuit is not entirely complete. Electric current originates from thunderstorm cloud tops and travels to the ionosphere, where it then leaks back down to the Earth's surface. Superimposed on this current is the dynamo generated from the interaction of the solar wind with Earth's magnetosphere. This paper investigates seasonal variations of the vertical electric field and current density as measured at the South Pole between 1991 and 1993. After initial data reduction, a model approach was used to decouple the magnetospheric and atmospheric components of the measurements. This approach calculated and subtracted the polar cap ionospheric potential from the measured data to obtain a signal of global tropospheric origin, in principle. The diurnal variations of the resulting data were averaged as a function of UT. These averages were calculated for the data as a whole and for the date sorted and binned by season and by magnetic activity level. The seasonally binned average results are consistent with recent papers indicating that the electric field measurement show global convective electrical activity to be a minimum during the Northern Hemisphere winter, in contradiction to the original 1929 Carnegie data. Because the electric field was a maximum during the Northern Hemisphere summer season, the midlatitude regions must contribute more strongly than the tropics to global atmospheric electricity. This analysis supports the link of electrical activity to global temperature. The magnetic activity binned results suggest that the polar cap potential model used underestimates the cross polar cap potential when there is a high Kp index.
Enantioselective alkynylations of aromatic and aliphatic aldehydes catalyzed by terpene derived chiral amino alcohols

Abstract Enantioselective alkynyl zinc additions to aromatic and aliphatic aldehydes have been studied using terpene derived chiral amino alcohol ligands. The limonene derived amino alcohol (1 R ,2 R ,5 S )-2-methyl-5-(1-methylethenyl)-2-(1-pyrrolidinyl)cyclohexanol gave the most promising results. Chiral propargylic alcohols were obtained in good yields and moderate enantioselectivities (up to 60%).
The Absence of Cold Dust and the Mineralogy and Origin of the Warm Dust Encircling BD +20 307

Spitzer Space Telescope photometry and spectroscopy of BD +20 307 show that all of the dust around this remarkable Gyr-old spectroscopic binary arises within 1 AU. No additional cold dust is needed to fit the infrared excess. Peaks in the 10 and 20 ?m spectrum are well fit with small silicates that should be removed on a timescale of years from the system. This is the dustiest star known for its age, which is 1 Gyr. The dust cannot arise from a steady-state collisional cascade. A catastrophic collision of two rocky, planetary-scale bodies in the terrestrial zone is the most likely source for this warm dust because it does not require a reservoir of planetesimals in the outer system.
Case study of Rb+(aq), quasi-chemical theory of ion hydration, and the no split occupancies rule

Quasi-chemical theory applied to ion hydration combines statistical mechanical theory, electronic structure calculations, and molecular simulation, disciplines which are individually subjects for specialized professional attention. Because it combines activities which are themselves non-trivial, quasi-chemical theory is typically viewed with surprise. Nevertheless, it provides a fully-considered framework for analysis of ion hydration. Furthermore, the initial calculations are indeed simple, successful, and provide new information to long-standing experimental activities such as neutron diffraction by hydrated ions. Here we review quasi-chemical theory in the context of a challenging application, Rb+(aq).
MEG-based imaging of focal neuronal current sources

The authors describe a new approach to imaging neural current sources from measurements of the magnetoencephalogram (MEG) associated with sensory, motor, or cognitive brain activation. Many previous approaches to this problem have concentrated on the use of weighted minimum norm (WMN) inverse methods. While these methods ensure a unique solution, they do not introduce information specific to the MEG inverse problem, often producing overly smoothed solutions and exhibiting severe sensitivity to noise. The authors describe a Bayesian formulation of the inverse problem in which a Gibbs prior is constructed to reflect the sparse focal nature of neural current sources associated with evoked response data. The authors demonstrate the method with simulated and experimental phantom data, comparing its performance with several WMN methods.
Challenges in stochastic programming

Remarkable progress has been made in the development of algorithmic procedures and the availability of software for stochastic programming problems. However, some fundamental questions have remained unexplored. This paper identifies the more challenging open questions in the field of stochastic programming. Some are purely technical in nature, but many also go to the foundations of designing models for decision making under uncertainty.
Task Trade Between Similar Countries

The authors propose a theory of task trade between countries that have similar relative factor endowments and technological capabilities but may differ in size. Firms produce differentiated goods by performing a continuum of tasks, each of which generates local spillovers. Tasks can be performed at home or abroad, but offshoring entails costs that vary by task. In equilibrium, the tasks with the highest offshoring costs may not be traded. Among the remainder, those with the relatively higher offshoring costs are performed in the country that has the higher wage and higher aggregate output. The paper discusses the relationship between equilibrium wages, equilibrium outputs, and relative country size and examines how the pattern of specialization reflects the key parameters of the model.
Maximum likelihood Bayesian averaging of spatial variability models in unsaturated fractured tuff

[1] Hydrologic analyses typically rely on a single conceptual-mathematical model. Yet hydrologic environments are open and complex, rendering them prone to multiple interpretations and mathematical descriptions. Adopting only one of these may lead to statistical bias and underestimation of uncertainty. Bayesian model averaging (BMA) [Hoeting et al., 1999] provides an optimal way to combine the predictions of several competing models and to assess their joint predictive uncertainty. However, it tends to be computationally demanding and relies heavily on prior information about model parameters. Neuman [2002, 2003] proposed a maximum likelihood version (MLBMA) of BMA to render it computationally feasible and to allow dealing with cases where reliable prior information is lacking. We apply MLBMA to seven alternative variogram models of log air permeability data from single-hole pneumatic injection tests in six boreholes at the Apache Leap Research Site (ALRS) in central Arizona. Unbiased ML estimates of variogram and drift parameters are obtained using adjoint state maximum likelihood cross validation [Samper and Neuman, 1989a] in conjunction with universal kriging and generalized least squares. Standard information criteria provide an ambiguous ranking of the models, which does not justify selecting one of them and discarding all others as is commonly done in practice. Instead, we eliminate some of the models based on their negligibly small posterior probabilities and use the rest to project the measured log permeabilities by kriging onto a rock volume containing the six boreholes. We then average these four projections and associated kriging variances, using the posterior probability of each model as weight. Finally, we cross validate the results by eliminating from consideration all data from one borehole at a time, repeating the above process and comparing the predictive capability of MLBMA with that of each individual model. We find that MLBMA is superior to any individual geostatistical model of log permeability among those we consider at the ALRS.
Discrete Scale Relativity and SX Phoenicis Variable Stars

Discrete Scale Relativity proposes a new symmetry principle called discrete cosmological self-similarity which relates each class of systems and phenomena on a given Scale of nature’s discrete cosmological hierarchy to the equivalent class of analogue systems and phenomena on any other Scale. The new symmetry principle can be understood in terms of discrete scale invariance involving the spatial, temporal and dynamic parameters of all systems and phenomena. This new paradigm predicts a rigorous discrete self-similarity between Stellar Scale variable stars and Atomic Scale excited atoms undergoing energy-level transitions and sub-threshold oscillations. Previously, methods for demonstrating and testing the proposed symmetry principle have been applied to RR Lyrae, δ Scuti and ZZ Ceti variable stars. In the present paper we apply the same analytical methods and diagnostic tests to a new class of variable stars: SX Phoenicis variables. Double-mode pulsators are shown to provide an especially useful means of testing the uniqueness and rigor of the conceptual principles and discrete self-similar scaling of Discrete Scale Relativity. These research efforts will help theoretical physicists to understand the fundamental discrete self-similarity of nature, and to model both stellar and atomic systems with one unified physics.
Physical Properties of Conventional Explosives Deduced from Radio Frequency Emissions

Los Alamos National Laboratory collected broadband radio frequency (RF) electric field change measurements from multiple detonations of high explosives (HE). Three types of HE were used: small cylinders of flake TNT, solid TNT, and PBX-9501. Low frequency signals ( 290 MHz) occurred later, were an order of magnitude lower in signal strength, and were not repeatable. There is a positive correlation between the maximum electric field change and the shock velocity of the HE. The amount of free charge produced in the explosion estimated from the first RF pulse is between 10 and 150 μC. This implies a weakly ionized plasma with temperatures between 2600 and 2900 K.
Follow the Leader: How Changes in Residential and Non-residential Investment Predict Changes in GDP

This paper examines the effect of different kinds of investments on the business cycle. Specifically, it examines whether residential and non-residential investment Granger cause GDP, and whether GDP Granger causes each of these types of investments. The paper uses quarterly National Income and Products Data for the period 1959 to 1992. Under a wide variety of time-series specifications, residential investment causes, but is not caused by GDP, while non-residential investment does not cause, but is caused by GDP. Thus, housing leads and other types of investment lag the business cycle. The results also suggest that policies designed to funnel capital away from housing into plant and equipment could produce severe short-run dislocations.
Input selection for parameter identification in discrete systems

In this paper we consider the problem of selecting an optimal input for identifying an unknown parameter of a known discrete system by observing its output in the presence of Gaussian noise. The system is considered to be a generalized discrete system in which the inputs and possible parameter values are members of a finite set. The criterion for the optimal input is defined as that which maximizes the probability of correctly determining the true parameter value from a multiple hypothesis test. Although the above criterion totally orders the set of inputs, it is a difficult task to select the best inputs. Some theorems are presented which yield a partial ordering whose extension is the desired total ordering. In the special case of strong noise it is shown that the ordering of inputs can be related to the perimeter in the output vector space. The results of the paper are applicable to the selection of both preset input lengths or to adaptive identification.
The Higher Rank Rigidity Theorem for Manifolds With No Focal Points

We say that a Riemannian manifold M has rank M ≥ k if every geodesic in M admits at least k parallel Jacobi fields. The Rank Rigidity Theorem of Ballmann and Burns–Spatzier, later generalized by Eberlein–Heber, states that a complete, irreducible, simply connected Riemannian manifold M of rank k ≥ 2 (the “higher rank” assumption) whose isometry group Γ satisfies the condition that the Γ-recurrent vectors are dense in SM is a symmetric space of noncompact type. This includes, for example, higher rank M which admit a finite volume quotient. We adapt the method of Ballmann and Eberlein–Heber to prove a generalization of this theorem where the manifold M is assumed only to have no focal points. We then use this theorem to generalize to no focal points a result of Ballmann–Eberlein stating that for compact manifolds of nonpositive curvature, rank is an invariant of the fundamental group.
Evolutionary Models of Women's Reproductive Functioning

Life history theory posits that natural selection leads to the evolution of mechanisms that tend to allocate resources to the competing demands of growth, reproduction, and survival such that fitness is locally maximized. (That is, among alternative allocation patterns exhibited in a population, those having the highest inclusive fitness will become more common over generational time.) Strategic modulation of reproductive effort is potentially adaptive because investment in a new conception may risk one's own survival, future reproductive opportunities, and/or current offspring survival. Several physiological and behavioral mechanisms modulate reproductive effort in human females. This review focuses on the hormonal changes that vary the probability of ovulation, conception, and/or continuing pregnancy and discusses evolutionary models that predict how and why these hormonal changes occur. Anthropological field studies have yielded important insights into the environmental correlates of variation in ovari...
A convenient method for functionalization of the 2-position of cyclodextrins

Abstract A new convenient strategy for functionalization of the 2-position of cyclodextrins involving deprotonation of cyclodextrin by sodium hydride followed by a nucleophilic attack of the resultant cyclodextrin oxyanion on the desired electrophile gives a high yield of the cyclodextrin derivative.
Radiation from a Uniformly Accelerated Charge and the Equivalence Principle

We argue that purely local experiments can distinguish a stationary charged particle in a static gravitational field from an accelerated particle in (gravity-free) Minkowski space. Some common arguments to the contrary are analyzed and found to rest on a misidentification of “energy.”
THE EFFECT OF DENSITY ZONING ON RACIAL SEGREGATION IN U.S. URBAN AREAS.

The authors argue that anti-density zoning increases Black residential segregation in U.S. metropolitan areas by reducing the quantity of affordable housing in White jurisdictions. Drawing on census data and local regulatory indicators compiled by Pendall, the authors estimate a series of regression models to measure the effect of maximum density zoning on Black segregation. Results estimated using ordinary least squares indicate a strong and significant cross-sectional relationship between low-density zoning and racial segregation, even after controlling for other zoning policies and a variety of metropolitan characteristics, a relationship that persists under two-stage least squares estimation. Both estimation strategies also suggest that anti-density zoning inhibits desegregation over time.
Numerical results for ground states of spin glasses on Bethe lattices

The average ground state energy and entropy for ±J spin glasses on Bethe lattices of connectivities k + 1 = 3..., 26 at T = 0 are approximated numerically. To obtain sufficient accuracy for large system sizes (up to n = 212), the Extremal Optimization heuristic is employed which provides high-quality results not only for the ground state energies per spin ek+1 but also for their entropies sk+1. The results indicate sizable differences between lattices of even and odd connectivities. The extrapolated ground state energies compare very well with recent one-step replica symmetry breaking calculations. These energies can be scaled for all even connectivities k + 1 to within a fraction of a percent onto a simple functional form, e k + 1 = E SK - (2E SK + )/ , where E SK = - 0.7633 is the ground state energy for the broken replica symmetry in the Sherrington-Kirkpatrick model. But this form is in conflict with perturbative calculations at large k + 1, which do not distinguish between even and odd connectivities. We also find non-zero entropies per spin sk+1 at small connectivities. While sk+1 seems to vanish asymptotically with 1/(k + 1) for even connectivities, it is numerically indistinguishable from zero already for odd k + 1 ≥ 9.
Tropical secant graphs of monomial curves

We construct and study an embedded weighted balanced graph in $\mathbb{R}^{n+1}$ parametrized by a strictly increasing sequence of $n$ coprime numbers $\{ i_1, \ldots, i_n\}$, called the $\textit{tropical secant surface graph}$. We identify it with the tropicalization of a surface in $\mathbb{C}^{n+1}$ parametrized by binomials. Using this graph, we construct the tropicalization of the first secant variety of a monomial projective curve with exponent vector $(0, i_1, \ldots, i_n)$, which can be described by a balanced graph called the $\textit{tropical secant graph}$. The combinatorics involved in computing the degree of this classical secant variety is non-trivial. One earlier approach to this is due to K. Ranestad. Using techniques from tropical geometry, we give algorithms to effectively compute this degree (as well as its multidegree) and the Newton polytope of the first secant variety of any given monomial curve in $\mathbb{P}^4$.
Off the rails: Is state ownership bad for productivity?

The performance of Indian railways in the nineteenth century provides a great context to study the eects of state ownership on productivity and other aspects of firm operations. We rely on a key feature of the institutional background whereby the colonial Government of India purchased a majority ownership stake in private railways at predetermined dates set by contracts negotiated decades before the companies came under state ownership. Controlling for individual railway fixed eects, year fixed eects, and railway-specific time trends, we find no evidence of a decline in TFP following state takeovers of private companies. Instead of reducing productivity, as the recent experiences with privatization would suggest, we find that the Government of India maintained productivity when it became the owner of railways. Government ownership influenced certain areas of operations such as the capital-labor ratio, but not others such as fares. Our results point to the conditions where state ownership is no worse than private ownership in terms of productivity.
Computation of limit-cycle oscillations of a delta wing

This paper presents computational simulations of limit cycle oscillations of a cropped delta wing. A newly developed aeroelastic solver which couples a well validated Navier-Stokes code with a nonlinear nite element method for the von Karman plate equations is employed. Previous computations using a linear structural modal solver to model the delta wing produced limit cycle oscillations with significantly larger amplitudes than the experimentally measured limit cycle response. The present computations with the nonlinear structural model produce limit cycle amplitudes commensurate with the experimental measurements. The computations presented in the paper demonstrate that the geometric nonlinearities in the structural model provide the proper nonlinear mechanism for the development of the limit cycle response observed in the experiments.
Relative payoffs and happiness: an experimental study

Some c urrent utility models presume that people a re c oncerned with their r elative standing in a reference group. If this is true, do certain types care more about this than others? Using simple binary decisions and self-reported h appiness, we investigate both the prevalence of “difference aversion” and whether happiness levels influence the taste for social comparisons. Our decision tasks distinguish b etween a person’s desire to achieving the social optimum, equality or advantageous relative standing. Most people appear to disregard relative payoffs, instead typically making choices resulting in higher social payoffs. While we do not find a strong general correlation between happiness and concern for relative payoffs, we do observe that a willingness to lower another person’s payoff below one’s own (competitive preferences) seems correlated with unhappiness.
Induction Of Endothelin‐1 Expression By Glucose: An Effect Of Protein Kinase C Activation

Enhanced actions or levels of endothelin-1 (ET-1), a potent vasoconstrictor, have been associated with decreased blood flow in the retina and peripheral nerves of diabetic animals and may be related to the development of pathologies in these tissues. Hyperglycemia has been postulated to increase ET-1 secretion in endothelial cells. We have characterized the mechanism by which elevation of glucose is increasing ET-1 mRNA expression in capillary bovine retinal endothelial cells (BREC) and bovine retinal pericytes (BRPC). Elevation of glucose, but not mannitol, from 5.5 to 25 mmol/l for 3 days increased membranous protein kinase C (PKC) activities and ET-1 mRNA in parallel levels by 2-fold in BREC and BRPC. These effects were reversed by decreasing glucose levels to 5.5 mmol/l for an additional 2 days. Glucose-induced ET-1 overexpression was inhibited by a general PKC inhibitor, GF109203X, and a mitogen-activated protein kinase kinase inhibitor, PD98059, but not by wortmannin, a phosphatidylinositol 3-kinase inhibitor. By immunoblot analysis, PKC-beta2 and -delta isoforms in BREC were significantly increased relative to other isoforms in the membranous fractions when glucose level was increased. Overexpression of PKC-beta1 and -delta isoforms but not PKC-zeta isoform by adenovirus vectors containing the respective cDNA enhanced in parallel PKC activities, proteins, and basal and glucose-induced ET-1 mRNA expression by at least 2-fold. These results showed that enhanced ET-1 expression induced by hyperglycemia in diabetes is partly due to activation of PKC-beta and -delta isoforms, suggesting that inhibition of these PKC isoforms may prevent early changes in diabetic retinopathy and neuropathy.
Instability in the Cobweb Model under the BNN dynamic

The cobweb model where firms choose between rational and naive forecasting strategies has a 2-cycle when the elasticity of supply is greater than the elasticity of demand for a number of different dynamics describing the evolution of strategy choices. This paper proves that the 2-cycle is exponentially unstable under the learning dynamic of Brown, von Neuman and Nash (1950). Issues arising in the analysis of piecewise smooth discrete time maps are discussed.
Adaptive Crowdsourcing Algorithms for the Bandit Survey Problem

Very recently crowdsourcing has become the de facto platform for distributing and collecting human computation for a wide range of tasks and applications such as information retrieval, natural language processing and machine learning. Current crowdsourcing platforms have some limitations in the area of quality control. Most of the effort to ensure good quality has to be done by the experimenter who has to manage the number of workers needed to reach good results. We propose a simple model for adaptive quality control in crowdsourced multiple-choice tasks which we call the bandit survey problem. This model is related to, but technically different from the well-known multi-armed bandit problem. We present several algorithms for this problem, and support them with analysis and simulations. Our approach is based in our experience conducting relevance evaluation for a large commercial search engine.
Recent results on beyond the standard model Higgs boson searches from CMS

Two extensions of the standard model, one that includes the seesaw mechanism of type II, and the minimal supersymmetric extention to the standard model, are studied using up to 1.6 fb−1 of data collected in proton-proton collisions at √s = 7 TeV with the CMS detector at the LHC.
Gamma-Ray Burst Beaming: A Universal Configuration with a Standard Energy Reservoir?

We consider a gamma-ray burst (GRB) model based on an anisotropic fireball with an axisymmetric energy distribution of the form (θ) θ-k and allow for the observer's viewing direction being at an arbitrary angle θv with respect to the jet axis. This model can reproduce the key features expected from the conventional on-axis uniform jet models, with the novelty being that the achromatic break time in the broadband afterglow light curves corresponds to the epoch during which the relativistic beaming angle is equal to the viewing angle, θv, rather than to the jet half-opening angle, θj. If all the GRB fireballs have such a similar energy distribution form with 1.5 < k 2, then GRBs may be modeled by a quasi-universal beaming configuration and an approximately standard energy reservoir. This conclusion also holds for some other forms of angular energy distributions, such as the Gaussian function.
The Hopf condition for bilinear forms over arbitrary fields

We settle an old question about the existence of certain ‘sums-of-squares’ formulas over a field F, related to the composition problem for quadratic forms. A classical theorem says that if such a formula exists over a field of characteristic 0, then certain binomial coe!cien ts must vanish. We prove that this result also holds over fields of characteristic p > 2.
Coherent transport through a quantum dot in a strong magnetic field

Abstract I discuss recent work on the phase of the transmission coefficient for tunneling through a quantum dot in the quantum Hall effect regime. The effects of electron–electron interaction on this phase is investigated with the use of finite-size bosonization techniques combined with perturbation theory resummation. New non-Fermi-liquid phenomena are predicted in the fractional quantum Hall regime that may be used to distinguish experimentally between Tomonaga–Luttinger and Fermi liquids.
Geometry and a priori estimates for free boundary problems of the Euler's equation

In this paper we derive estimates to the free boundary problem for the Euler equation with surface tension, and without surface tension provided the Rayleigh-Taylor sign condition holds. We prove that as the surface tension tends to 0, when the Rayleigh-Taylor condition is satisfied, solutions converge to the Euler flow with zero surface tension. © 2007 Wiley Periodicals, Inc.
Parks and Peoples: The Social Impact of Protected Areas

This review examines the social, economic, and political effects of environmental conservation projects as they are manifested in protected areas. We pay special attention to people living in and displaced from protected areas, analyze the worldwide growth of protected areas over the past 20 years, and offer suggestions for future research trajectories in anthropology. We examine protected areas as a way of seeing, understanding, and producing nature (environment) and culture (society) and as a way of attempting to manage and control the relationship between the two. We focus on social, economic, scientific, and political changes in places where there are protected areas and in the urban centers that control these areas. We also examine violence, conflict, power relations, and governmentality as they are connected to the processes of protection. Finally, we examine discourse and its effects and argue that anthropology needs to move beyond the current examinations of language and power to attend to the ways in which protected areas produce space, place, and peoples.
Self-insurance vs. self-financing: A welfare analysis of the persistence of shocks

Abstract We study the welfare cost of market incompleteness in a generalized Bewley model where idiosyncratic risk takes the form of entrepreneurial productivity shocks. Market incompleteness in our framework has two dimensions. First, in the Bewley tradition, only a limited set of instruments for consumption smoothing is available. Second, entrepreneursʼ capital rental is subject to collateral constraints. As is well known, it is harder to self-insure against more persistent shocks, and the welfare cost of missing consumption insurance increases with shock persistence. On the other hand, with collateral constraints, an increase in shock persistence leads to better allocation of production factors through entrepreneursʼ self-financing, and the welfare cost of imperfect capital rental markets decreases with shock persistence. The overall welfare cost of market incompleteness can be increasing, decreasing, or even non-monotone in shock persistence, depending on the relative strengths of its two components—the cost of missing insurance and the cost of imperfect capital markets.
Palladium-catalyzed cross-coupling of α-bromocarbonyls and allylic alcohols for the synthesis of α-aryl dicarbonyl compounds

The palladium-catalyzed coupling of olefins and organohalides is a versatile approach for synthesizing complex molecules from simple starting materials. We have developed a palladium-catalyzed coupling of α-bromocarbonyl compounds with allylic alcohols for the generation of acyclic aryl-substituted dicarbonyl compounds. The reaction proceeds via a tandem olefin insertion of an α-acyl radical followed by a 1,2-aryl migration. In addition to providing preliminary evidence for a free radical mediated mechanism, we demonstrate unprecedented levels of 1,3-stereoinduction for the 1,2-migration step.
New solvable stochastic volatility models for pricing volatility derivatives

In this paper we discuss a new approach to extend a class of solvable stochastic volatility models (SVM). Usually, classical SVM adopt a CEV process for instantaneous variance where the CEV parameter γ takes just few values: 0—the Ornstein–Uhlenbeck process, 1/2—the Heston (or square root) process, 1—GARCH, and 3/2—the 3/2 model. Some other models, e.g. with γ = 2 were discovered in Henry-Labordere (Analysis, geometry, and modeling in finance: advanced methods in option pricing. Chapman & Hall/CRC Financial Mathematics Series, London, 2009) by making connection between stochastic volatility and solvable diffusion processes in quantum mechanics. In particular, he used to build a bridge between solvable superpotentials (the Natanzon superpotentials, which allow reduction of a Schrodinger equation to a Gauss confluent hypergeometric equation) and existing SVM. Here we propose some new models with $${\gamma \in \mathbb{R}}$$ and demonstrate that using Lie’s symmetries they could be priced in closed form in terms of hypergeometric functions. Thus obtained new models could be useful for pricing volatility derivatives (variance and volatility swaps, moment swaps).
The Missing Manual: Using National Student Clearinghouse Data to Track Postsecondary Outcomes.

This article explores the promises and pitfalls of using National Student Clearinghouse (NSC) data to measure a variety of postsecondary outcomes. We first describe the history of the NSC, the basic structure of its data, and recent research interest in using NSC data. Second, using information from the Integrated Postsecondary Education Data System (IPEDS), we calculate enrollment coverage rates for NSC data over time, by state, institution type, and demographic student subgroups. We find that coverage is highest among public institutions and lowest (but growing) among for-profit colleges. Across students, enrollment coverage is lower for minorities but similar for males and females. We also explore two potentially less salient sources of non-coverage: suppressed student records due to privacy laws and matching errors due to typographic inaccuracies in student names. To illustrate how this collection of measurement errors may affect estimates of the levels and gaps in postsecondary attendance and persist...
Technical Efficiency Analysis of Micro-enterprises: Theoretical and Methodological Approach of the Stochastic Frontier Production Functions Applied to Nigerian Data

This study was carried out to analyse the technical efficiency of micro-enterprises in the Nigerian economy, using cross-sectional data collected on micro-enterprises selected from block-making, metal-fabricating and sawmilling enterprises in the three geographical regions (north, southwest and southeast regions) of Nigeria. The Nigerian government has put in efforts at promoting productivity and efficiency in both public and private sectors of the economy. The ability of Nigerian economy to experience accelerated economic growth both in the short and in the long run depends on the exploitation of the potential within the micro-enterprises sector of the economy. The importance of this sector is reflected in the current economic reform programme of the Federal Government of Nigeria under the National Economic Empowerment Development Strategy (NEEDS). NEEDS is a comprehensive two- to three-year economic growth and poverty reduction plan. It then becomes important to study the current level of technical efficiency within the micro-enterprises sub-sector. Data collected were analysed using the stochastic frontier production functions. The results of the analysis show that the enterprises have varying level of technical efficiencies across enterprises, across scales of operation and across regions. Of the three geographical regions, both the least and the highest technical efficiencies come from micro-enterprises located in the southeastern regions of Nigeria. The mean technical efficiencies range between 0.66 for sawmilling enterprises and 0.82 for metal-fabricating enterprises. The results indicate that while the level of education, level of investment and number of employees positively and significantly affect the level of technical efficiency, age of enterprise, as well as age of enterprise operator/decision-maker, negatively influences the level of technical efficiency. The results of tests of hypotheses show that there is no significant difference in technical efficiency across the scale of operation, but the hypothesis of no significant difference in technical efficiency across geographical zones is rejected. Copyright 2008 The author 2007. Published by Oxford University Press on behalf of the Centre for the Study of African Economies. All rights reserved. For permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.
Practical acid-catalyzed acylation of sulfonamides with carboxylic acid anhydrides

A highly efficient reaction between sterically and electronically diverse sulfonamides and carboxylic acid anhydrides to furnish monoacylated N-acylsulfonamides is described. This represents the first systematic disclosure of the scope of sulfuric acid-catalyzed acylation of sulfonamides.
Indium-mediated allylation reaction of difluoroacetyltrialkylsilanes in aqueous media

Indium-mediated allylations of difluoroacetyltrialkylsilanes in aqueous media give homoallylic alcohols exclusively. The common Brook rearrangement C- to O-silyl group migration is totally suppressed with no detectable formation of enol silyl ethers. The influence of water on the allylation reaction is also described.
On the evolution of jet energy and opening angle in strongly coupled plasma

We calculate how the energy and the opening angle of jets in $$ \mathcal{N} $$ = 4 SYM theory evolve as they propagate through the strongly coupled plasma of that theory. We define the rate of energy loss dE jet /dx and the jet opening angle in a straightforward fashion directly in the gauge theory before calculating both holographically, in the dual gravitational description. In this way, we rederive the previously known result for dE jet /dx without the need to introduce a finite slab of plasma. We obtain a striking relationship between the initial opening angle of the jet, which is to say the opening angle that it would have had if it had found itself in vacuum instead of in plasma, and the thermalization distance of the jet. Via this relationship, we show that $$ \mathcal{N} $$ = 4 SYM jets with any initial energy that have the same initial opening angle and the same trajectory through the plasma experience the same fractional energy loss. We also provide an expansion that describes how the opening angle of the $$ \mathcal{N} $$ = 4 SYM jets increases slowly as they lose energy, over the fraction of their lifetime when their fractional energy loss is not yet large. We close by looking ahead toward potential qualitative lessons from our results for QCD jets produced in heavy collisions and propagating through quark-gluon plasma.
Soluble dipolar dendrimers with peripheral sulfone groups

Abstract A dipolar dendron based on meta and para linked poly(phenyl acetylene)s with eight electron donor–acceptor pairs in direct conjugations is synthesized through a convergent approach.
Resilient P2P anonymous routing by using redundancy

One hurdle to using peer-to-peer (P2P) networks as anonymising networks is churn. Node churn makes anonymous paths fragile and short-lived: failures of a relay node disrupt the path, resulting in message loss and communication failures. To make anonymous routing resilient to node failures, we take two steps: 1) we use a simple yet powerful idea based on message redundancy by erasure coding and path redundancy to mask node failures; 2) we base mix choices of a path on node lifetime prediction and choose stable nodes as relay nodes, thereby prolonging single path durability. We present an allocation of erasure-coded message segments among multiple paths that provides a guideline on how to maximise routing resilience upon different node availabilities in real-world systems. Via detailed simulations, we compare routing resilience of our approach and existing anonymity protocols, showing that our approach greatly improves routing resilience while consuming modest bandwidth.
Low voltage/low power microwave electronics

Simultaneous reduction in operating voltage and optimization of performance is a significant problem for portable wireless designers. Achievement of these conflicting goals requires careful consideration and design of semiconductor materials, transistor devices, circuit topologies and system architectures. Each of these issues is explored and discussed as they affect these problems.
Predictors of posttraumatic stress disorder and symptoms in adults: A meta-analysis.

A review of 2,647 studies of posttraumatic stress disorder (PTSD) yielded 476 potential candidates for a meta-analysis of predictors of PTSD or of its symptoms. From these, 68 studies met criteria for inclusion in a meta-analysis of 7 predictors: (a) prior trauma, (b) prior psychological adjustment, (c) family history of psychopathology, (d) perceived life threat during the trauma, (e) posttrauma social support, (f) peritraumatic emotional responses, and (g) peritraumatic dissociation. All yielded significant effect sizes, with family history, prior trauma, and prior adjustment the smallest (weighted r = .17) and peritraumatic dissociation the largest (weighted r = .35). The results suggest that peritraumatic psychological processes, not prior characteristics, are the strongest predictors of PTSD.
Decentralized risk-sensitive controller design for strict-feedback systems

This paper studies decentralized control of uncertain systems. The class of systems focused on is a set of stochastic strict-feedback systems which interact through their outputs, and performance is measured with respect to a risk sensitive cost criterion. The unknown nonlinear interconnection terms are assumed to be bounded by some known functions of the outputs of the subsystems, multiplied by some unknown parameters. The controllers designed for each subsystem have access only to the information available with regard to the respective subsystem, and they achieve an arbitrarily small value for the risk-sensitive cost for the overall system. Under this completely decentralized control scheme, all closed-loop signals remain bounded in probability.
PATH CONSISTENCY REVISITED

One of the main factors limiting the use of path consistency algorithms in real life applications is their high space complexity. Han and Lee proposed a path consistency algorithm, PC-4, with O(n3a3) space complexity, which makes it practicable only for small problems. I present a new path consistency algorithm, PC-5, which has an O(n3a2) space complexity while retaining the worst-case time complexity of PC-4. Moreover, the new algorithm exhibits a much better average-case time complexity. The new algorithm is based on the idea (due to Bessiere) that, at any time, only a minimal amount of support has to be found and recorded for a labeling to establish its viability; one has to look for a new support only if the current support is eliminated. I also show that PC-5 can be improved further to yield an algorithm, PC5++, with even better average-case performance and the same space complexity.
Minimizing the expected lifetime spent in drawdown under proportional consumption

Abstract We determine the optimal amount to invest in a Black–Scholes financial market for an individual who consumes at a rate equal to a constant proportion of her wealth and who wishes to minimize the expected time that her wealth spends in drawdown during her lifetime. Drawdown occurs when wealth is less than some fixed proportion of maximum wealth. We compare the optimal investment strategy with those for three related goal-seeking problems and learn that the individual is myopic in her investing behavior, as expected from other goal-seeking research.