cssi/SciSciGPT-SciSciNet huggingface dataset:
Effect of hetastarch, mannitol, and phenylephrine on spinal cord blood flow following experimental spinal injury

Anesthetized lambs were subjected to epidural cord compression at T13 by means of an epidural balloon distended to 200 mmHg for 80 minutes. Determinations of spinal cord blood flow (SCBF) were made by labelled microspheres prior to and during compression, and then 1/2, 1 1/2, and 2 1/2 hours after compression. Twelve control animals received saline (80 ml/h). Nine animals received hetastarch (a 20 ml/kg bolus followed by an 80 ml/h infusion) and 8 animals received mannitol (a 1 g/kg bolus followed by 1 g/kg/hr). An additional 10 animals received phenylephrine to raise mean arterial pressure by 20 to 40%. Somatosensory evoked potentials (SEPs) were recorded following each determination of SCBF. Animals were killed following determination of the 2 1/2 hour postcompressive flow. The animals treated with either hetastarch or phenylephrine had a postcompressive mean arterial pressure that was significantly greater than that of the controls (P less than 0.01). During treatment, cardiac output in the hetastarch and mannitol animals was significantly greater and hematocrit significantly less than in the controls (P less than 0.05). In spite of these changes, postcompressive SCBF was significantly increased only in those animals treated with phenylephrine (P less than 0.05). Statistical analysis of the relationship between mean arterial pressure and postcompressive SCBF revealed that autoregulation is indeed lost with this experimental model of spinal cord injury. Histological examination of the injured site failed to demonstrate any difference in the area of hemorrhagic necrosis among the four groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Preparation of Dispersed Phase Ceramic Boron Nitride and Aluminum Nitride Composite Coatings by Chemical Vapor Deposition

Dispersed phase ceramic composite coatings containing BN and AIN were prepared by chemical vapor deposition. The BN + AIN coatings were deposited on Al2O3 from the BCI3–AICI3-NH3 reagent system in the temperature range of 700° to 1200°C. Also, single-phase BN and AIN coatings were prepared for comparison purposes. The composite coatings consisted of very small BN and AIN regions which were either crystalline or amorphous, depending on deposition temperature and reagent concentrations. For example, a composite containing AlN whiskers of less than 100-nm diameter in a matrix of turbostratic BN of 2-nm grain size was deposited at 1100°C and 20 kPa.
Network Risk Limiting Dispatch: Optimal Control and Price of Uncertainty

Increased uncertainty due to high penetration of re- newables imposes significant costs to the system operators. The added costs depend on several factors including market design, performance of renewable generation forecasting and the specific dispatch procedure. Quantifying these costs has been limited to small sample Monte Carlo approaches applied specific dispatch algorithms. The computational complexity and accuracy of these approaches has limited the understanding of tradeoffs between different factors. In this work we consider a two-stage stochastic economic dispatch problem. Our goal is to provide an analytical quantification and an intuitive understanding of the effects of un- certainties and network congestion on the dispatch procedure and the optimal cost. We first consider an uncongested network and calculate the risk limiting dispatch. In addition, we derive the price of uncertainty, a number that characterizes the intrinsic impact of uncertainty on the integration cost of renewables. Then we extend the results to a network where one link can become congested. Under mild conditions, we calculate price of uncertainty even in this case. We show that risk limiting dispatch is given by a set of deterministic equilibrium equations. The dispatch solution yields an important insight: congested links do not create isolated nodes, even in a two-node network. In fact, the network can support backflows in congested links, that are useful to reduce the uncer- tainty by averaging supply across the network. We demonstrate the performance of our approach in standard IEEE benchmark networks.
Large-Scale Discovery of ERK2 Substrates Identifies ERK-Mediated Transcriptional Regulation by ETV3

The mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase 2 (ERK2) is ubiquitously expressed in mammalian tissues and is involved in a wide range of biological processes. Although MAPKs have been intensely studied, identification of their substrates remains challenging. We have optimized a chemical genetic system using analog-sensitive ERK2, a form of ERK2 engineered to use an analog of adenosine 5'-triphosphate (ATP), to tag and isolate ERK2 substrates in vitro. This approach identified 80 proteins phosphorylated by ERK2, 13 of which are known ERK2 substrates. The 80 substrates are associated with diverse cellular processes, including regulation of transcription and translation, mRNA processing, and regulation of the activity of the Rho family guanosine triphosphatases. We found that one of the newly identified substrates, ETV3 (a member of the E twenty-six family of transcriptional regulators), was extensively phosphorylated on sites within canonical and noncanonical ERK motifs. Phosphorylation of ETV3 regulated transcription by preventing its binding to DNA at promoters for several thousand genes, including some involved in negative feedback regulation of itself and of upstream signals.
Debt overhang and economic growth–the Asian and the Latin American experiences

Abstract Debt overhang may impede a country's investment and growth. Accordingly, the World Bank initiated debt relief programs. However, doubts have been raised regarding the empirical validity of the debt overhang hypothesis. We employ panel data for testing the existence of debt overhang for Latin American and Asian borrowers. A variety of dynamic panel data econometric estimations as well as dynamic and system GMM estimations are conducted. Our results indicate that debt overhang impeded growth in Latin American economies severely and the impact was moderately negative in the Asian region.
FRACTAL ANALYSES OF ANISOTROPIC FRACTURE SURFACES

Natural surfaces of rock fractures often have anisotropic asperity distributions, especially for shear fractures or faults. The asperity distributions could be treated as self-affine fractals with ...
Minimax and Adaptive Inference in Nonparametric Function Estimation

Since Stein’s 1956 seminal paper, shrinkage has played a fundamental role in both parametric and nonparametric inference. This article discusses minimaxity and adaptive minimaxity in nonparametric function estimation. Three interrelated problems, function estimation under global integrated squared error, estimation under pointwise squared error, and nonparametric confidence intervals, are considered. Shrinkage is pivotal in the development of both the minimax theory and the adaptation theory. While the three problems are closely connected and the minimax theories bear some similarities, the adaptation theories are strikingly different. For example, in a sharp contrast to adaptive point estimation, in many common settings there do not exist nonparametric confidence intervals that adapt to the unknown smoothness of the underlying function. A concise account of these theories is given. The connections as well as differences among these problems are discussed and illustrated through examples.
Neuroelectronics and modeling of electrical signals for monitoring and control of Parkinson's disease

The brain and the human nervous system are perhaps the most researched but least understood components of the human body. This is so because of the complex nature of its working and the high density of functions. The monitoring of neural signals could help one better understand the working of the brain and newer recording and monitoring methods have been developed ever since it was discovered that the brain communicates internally by means of electrical pulses. Neuroelectronics is the field which deals with the interface between electronics or semiconductors to living neurons. This includes monitoring of electrical activity from the brain as well as the development of feedback devices for stimulation of parts of the brain for treatment of disorders. In this paper these electrical signals are modeled through a nano/microelectrode arrays based on the electronic equivalent model using Cadence PSD 15.0. The results were compared with those previously published models such as Kupfmuller and Jenik's model, McGrogan's Neuron Model which are based on the Hodgkin and Huxley model. We have developed and equivalent circuit model using discrete passive components to simulate the electrical activity of the neurons. The simulated circuit can be easily be modified by adding some more ionic channels and the results can be used to predict necessary external stimulus needed for stimulation of neurons affected by the Parkinson's disease (PD). Implementing such a model in PD patients could predict the necessary voltages required for the electrical stimulation of the sub-thalamus region for the control tremor motion.
Active self-assembly of algorithmic shapes and patterns in polylogarithmic time

We describe a computational model for studying the complexity of self-assembled structures with active molecular components. Our model captures notions of growth and movement ubiquitous in biological systems. The model is inspired by biology's fantastic ability to assemble biomolecules that form systems with complicated structure and dynamics, from molecular motors that walk on rigid tracks and proteins that dynamically alter the structure of the cell during mitosis, to embryonic development where large scale complicated organisms efficiently grow from a single cell. Using this active self-assembly model, we show how to efficiently self-assemble shapes and patterns from simple monomers. For example we show how to grow a line of monomers in time and number of monomer states that is merely logarithmic in its length. Our main results show how to grow arbitrary connected two-dimensional geometric shapes and patterns in expected time polylogarithmic in the size of the shape plus roughly the time required to run a Turing machine deciding whether or not a given pixel is in the shape. We do this while keeping the number of monomer types logarithmic in shape size, plus monomers required by the Kolmogorov complexity of the shape or pattern. This work thus highlights the fundamental efficiency advantage of active self-assembly over passive self-assembly and motivates experimental effort to construct self-assembly systems with active molecular components.
An Improved Synthetic Method of 1-Chloro-7-methoxy-9H-thioxanthen-9-one

Abstract 1-Chloro-7-methoxy-9H-thioxanthen-9-one (3) was prepared via cyclization of 2-chloro-6-(4-methoxyphenylthio)-benzonitrile (1) in a one pot, two step reaction with improved yield (60%) over the previous literature report.
Domain-specific effects of stereotypes on performance

We report the results of an experiment mirroring an earlier study that found that Asian American women performed better on a math test when their Asian identity was salient and worse when their female identity was salient (Ambady, Shih, Kim, & Pittinsky, 2001; Shih, Ambady, Richeson, Fujita, & Gray, 2002; Shih, Pittinsky, & Ambady, 1999). In this paper, we assessed the performance of Asian American women on a verbal test, a situation in which the valence of the stereotypes associated with the same two identities (i.e., female, Asian) is reversed. Consistent with the stereotypes, women performed better on the verbal test when their female identity was made salient than when their Asian identity was made salient. These results, taken together with the previous findings, indicate that identities are not globally adaptive or maladaptive.
Explicit Constructions of Centrally Symmetric $$k$$-Neighborly Polytopes and Large Strictly Antipodal Sets

We present explicit constructions of centrally symmetric $$2$$-neighborly $$d$$-dimensional polytopes with about $$3^{d/2}\approx (1.73)^d$$ vertices and of centrally symmetric $$k$$-neighborly $$d$$-polytopes with about $$2^{{3d}/{20k^2 2^k}}$$ vertices. Using this result, we construct for a fixed $$k\ge 2$$ and arbitrarily large $$d$$ and $$N$$, a centrally symmetric $$d$$-polytope with $$N$$ vertices that has at least $$\left( 1-k^2\cdot (\gamma _k)^d\right) \genfrac(){0.0pt}{}{N}{k}$$ faces of dimension $$k-1$$, where $$\gamma _2=1/\sqrt{3}\approx 0.58$$ and $$\gamma _k = 2^{-3/{20k^2 2^k}}$$ for $$k\ge 3$$. Another application is a construction of a set of $$3^{\lfloor d/2 -1\rfloor }-1$$ points in $$\mathbb R ^d$$ every two of which are strictly antipodal as well as a construction of an $$n$$-point set (for an arbitrarily large $$n$$) in $$\mathbb R ^d$$ with many pairs of strictly antipodal points. The two latter results significantly improve the previous bounds by Talata, and Makai and Martini, respectively.
A double motion-compensated orthogonal transform with energy concentration constraint

This paper discusses a transform for successive pictures of an image sequence which strictly maintains orthogonality while permitting 2-hypothesis motion compensation between pairs of pictures. We extend previous work on an orthogonal transform for image sequences which uses only 1-hypothesis motion compensation between pairs of pictures. This work is motivated by the well known fact that the motion-compensated lifted Haar wavelet maintains orthogonality only approximately. In the case of zero motion fields, the motion-compensated lifted Haar wavelet is known to be orthogonal. But for complex motion fields with many multi-connected and unconnected pixels, the motion-compensated lifted Haar wavelet cannot accurately maintain its transform property and, hence, suffers a performance degradation. The presented double motion-compensated orthogonal transform strictly maintains orthogonality for any motion field. For the transform, each pixel in the high-band is compensated by a linear combination of two motion-compensated pixels chosen from the corresponding low-band. That is, each pixel in the high-band is associated with two motion vectors. This is in contrast to the previously presented single motion-compensated orthogonal transform where each pixel in the high-band is compensated by only one motion-compensated pixel chosen from the corresponding low-band. In terms of energy concentration, the double motion-compensated orthogonal transform outperforms the single motion-compensated orthogonal transform and compares favorably with the double motion-compensated lifted Haar wavelet.
Enceladus : A potential source of ammonia products and molecular nitrogen for Saturn's magnetosphere

[1] The detection of nitrogen species in Saturn's magnetosphere could, in principle, provide clues to the origin and evolution of its satellites and tenuous rings. Smith et al. (2005) first identified low-energy N+ using the Cassini Plasma Spectrometer (CAPS). N+ was predominantly seen in the Saturn's inner magnetosphere (<∼14 Rs), indicating an Enceladus nitrogen source rather than the expected Titan source. However, the parent molecular species was not confirmed. Subsequent modeling showed that a small N2 source at Enceladus consistent with ion neutral mass spectrometer observations could produce the observed spatial distribution of N+. Considering the significance of understanding the Enceladus plumes, identifying the molecular parent for the observed N+ (N2 or NHx) can provide clues to the subsurface composition of Enceladus and the processes generating this plume activity. In this paper, we expand on the work of Smith et al. (2007) to identify the source molecules for nitrogen ions detected in Saturn's inner magnetosphere. We conduct an extensive study of all available CAPS data to determine if N2+ or ammonia is the parent molecule for these nitrogen ions. We present evidence for the detection of product ions (NHx+), likely from ammonia, and provide upper limits on the amount of N2+ that may be present in the plasma in the inner magnetosphere.
Wireless Network Code Design and Performance Analysis Using Diversity-Multiplexing Tradeoff

Network coding and cooperative communication have received considerable attention from the research community recently in order to mitigate the adverse effects of fading in wireless transmissions and at the same time to achieve high throughput and better spectral efficiency. In this work, we design and analyze deterministic and random network coding schemes for a cooperative communication setup with multiple sources and destinations. We show that our schemes outperform conventional cooperation in terms of the diversity-multiplexing tradeoff (DMT). Specifically, it can offer the maximum diversity order at the expense of a slightly reduced multiplexing rate. We derive the necessary and sufficient conditions to achieve the maximum diversity order. We show that when the parity-check matrix for a systematic maximum distance separable (MDS) code is used as the network coding matrix, the maximum diversity is achieved. We present two ways to generate full-diversity network coding matrices: namely using the Cauchy matrices and the Vandermonde matrices. We also analyze a selection relaying scheme and prove that a multiplicative diversity order is possible with enough number of relay selection rounds.
Modification of Earth-satellite orbits using medium-energy pulsed lasers

Laser impulse space propulsion (LISP) has become an attractive concept, due to recent advances in gas laser technology, high-speed segmented mirrors, and improved coefficients for momentum coupling to targets in pulsed laser ablation. There are numerous specialized applications of the basic concept to space science -- ranging from far-future and high capital cost to the immediate and inexpensive, such as: LEO-LISP (launch of massive objects into low-Earth-orbit at dramatically improved cost-per-kg relative to present practice); LEGO-LISP (LEO to geosynchronous transfers); LO-LISP (periodic re-boost of decaying LEO orbits); and LISK (geosynchronous satellite station-keeping). It is unlikely that one type of laser will be best for all scenarios. In this paper, we discuss these most immediate applications, leaving LEO-LISP -- the application requiring the longest reach -- for another venue.
An interacting control systems analysis of the human lens accommodative controller

In this paper a mathematical control systems model of the human lens accommodative controller is derived. The model accounts for the interaction of the pupil with accommodation and thereby becomes a two-loop interacting control system. The lens and pupil dynamical equations are derived from classical muscle mechanics and experiments as well as from experiments performed by the author on cats, primates and humans. The animal experiments represent open-loop identification procedures designed to identify the dynamics of accommodation without neurological control. The human experiments are closed-loop procedures used to verify the overall system responses with the system under neurological control. The resultant systems model is computer simulated assuming a relay-type neurological control for both pupil and lens systems.
A combinatorial approach to monotonic independence over a C∗-algebra

The notion of monotonic independence, introduced by N. Muraki, is considered in a more general frame, similar to the construction of operator-valued free probability. The paper presents constructions for maps with similar properties to the H and K transforms from the literature, semi inner-product bimodule analogues for the monotone and weakly monotone product of Hilbert spaces, an ad-hoc version of the Central Limit Theorem, an operator-valued arsine distribution as well as a connection to operator-valued conditional freeness.
Non-coherent distributed space-time processing for multiuser cooperative transmissions

User cooperation can provide spatial transmit diversity gains, enhance coverage and potentially increase capacity. Existing works have focused on two-user cooperative systems with perfect channel state information at the receivers. In this paper, we develop several distributed space-time processing schemes for general N-user cooperative systems, which do not require channel state information at either relays or destination. We prove that full spatial diversity gain can be achieved in such systems. Simulations demonstrate that these cooperative schemes achieve significant performance gain
Short Distance Contributions to Graviton-Graviton Scattering: Matrix Theory versus Supergravity

We study graviton scattering in the presence of higher dimensional operators — particularly, R^4 — arising from loop effects. We find that the results do not correspond to any known terms in the effective action of Matrix theory, thus lending support to the idea that the finite N Matrix theory has no simple relation to supergravity with large compactification radii.
Military psychiatry and changing systems of mental health care

Abstract The unique opportunities of military psychiatry in dealing with situationally-induced emotional disorders have provided operational concepts and procedures which have strongly influenced the development of social and community psychiatry. From the experiences of military psychiatry have come (1) recognition of social and environmental determinants in the causation of mental illness, (2) repeated demonstration that locally based facilities furnish optimum conditions for the prevention, intervention and treatment of mental disorders and, (3) awareness and utilization of therapeutic benefits that can be derived from personnel attitudes, administrative structure, and other aspects of the treatment environment. These contributions of military psychiatry have become incorporated in present day changes in the delivery of mental health services from prolonged care in remote institutions to treatment within the community by locally based facilities.
Formulation of Analytical Design Derivatives for Nonlinear Unsteady Aeroelasticity

The engineering community has devoted considerable recent attention to non-traditional aircraft concepts, where nonlinear, unsteady, coupled aeroelastic physics have been found to drive the design process. There is a lack of current research aimed at bringing these physical concepts into a formal optimization environment, which is the focus of the current work. A numerical framework is developed to capture the unsteady aeroelastic interactions between a nonlinear shell and the surrounding flow. An analytical sensitivity analysis of the model is then discussed, computing the derivative of the aerodynamic force production with respect to a large vector of structural design variables. The work concludes with a series of gradient-based aeroelastic optimization studies, demonstrating the efficacy of analytical gradients towards tailoring the complex interaction between fluid and structure for optimal performance. I. Introduction
Toroidal orientifolds in IIA with general NS-NS fluxes

Type IIA toroidal orientifolds offer a promising toolkit for model builders, especially when one includes not only the usual fluxes from NS-NS and R-R field strengths, but also fluxes that are T-dual to the NS-NS three-form flux. These new ingredients are known as metric fluxes and non-geometric fluxes, and can help stabilize moduli or can lead to other new features. In this paper we study two approaches to these constructions, by effective field theory or by toroidal fibers twisted over a toroidal base. Each approach leads us to important observations, in particular the presence of D-terms in the four-dimensional effective potential in some cases, and a more subtle treatment of the quantization of the general NS-NS fluxes. Though our methods are general, we illustrate each approach on the example of an orientifold of T6/4.
Neutrino-Accelerated Hot Hydrogen Burning

We examine the effects of significant electron antineutrino fluxes on hydrogen burning. Specifically, we find that the bottleneck weak nuclear reactions in the traditional p-p chain and the hot CNO cycle can be accelerated by antineutrino capture, increasing the energy generation rate. We also discuss how antineutrino capture reactions can alter the conditions for break out into the rp-process. We speculate on the impact of these considerations for the evolution and dynamics of collapsing very massive and supermassive compact objects.
Active Stimulation of the Auroral Plasma

A concept of actively stimulating the auroral plasma using a high power pulsed HF radio wave transmitting system is described. A unique feature of a pulsed modular system is the unprecedentedly high power (e.g. 10–100 MW) that can be achieved. This pulsed HF system would be used in the excitation of short-term nonlinear plasma phenomena, such as resonant enhancement, particle energization, electron density profile modification, excitation of VLF plasma waves and the modification of auroral optical emission. This excitation is predicted on the basis of previous experience, which includes laboratory simulation experiments at high pulsed power, low latitude excitation of the ionospheric plasma, and theoretical calculations.
Analogues of the Artin factorization formula for the automorphic scattering matrix and Selberg zeta-function associated to a Kleinian group

For Kleinian groups acting on a hyperbolic three-space, we prove factorization formulas for both the Selberg zeta-function and the automorphic scattering matrix. We extend results of Venkov and Zograf from Fuchsian groups to Kleinian groups, and we give a proof that is simple and extendable to more general groups.
A concomitant allylic azide rearrangement/intramolecular azide-alkyne cycloaddition sequence

An intramolecular Huisgen cycloaddition of an interconverting set of isomeric allylic azides with alkynes affords substituted triazoles in high yield. The stereoisomeric vinyl-substituted triazoloxazines formed depend on the rate of cycloaddition of the different allylic azide precursors when the reaction is carried out under thermal conditions. In contrast, dimerized macrocyclic products were obtained when the reaction was done using copper(I)-catalyzed conditions, demonstrating the ability to control the reaction products through changing conditions.
Ureteral Obstructions and Leaks After Renal Transplantation: Outcome of Percutaneous Antegrade Ureteral Stent Placement in 44 Patients

PURPOSE: To analyze the outcome of percutaneous antegrade ureteral stent placement for treatment of ureteral stenoses and leaks after renal transplantation. MATERIALS AND METHODS: Antegrade pyelography and percutaneous ureteral stent placement were performed in 45 patients with ureteral obstruction (n = 40), leak (n = 3), or both (n = 2). Obstructions were graded as mild, moderate, or complete, and as early ( 3 months). RESULTS: The outcome of stent placement was successful in 25 (57%) patients (average follow-up, 30 months). The ureteroneocystostomy (UNC) was the most common site of obstructions (22 of 41), leaks (four of five), and successful outcomes (16 of 22). Moderate obstructions were most common (29 of 41) and responded best to treatment (17 of 29). Eighteen (69%) of 26 early obstructions and five (33%) of 15 late obstructions were successfully managed percutaneously. All complications (12 of 45 patients) were minor, with infections the most common ...
The link proteins

Aggregates of chondroitin-keratan sulfate proteoglycan (aggrecan) and hyaluronic acid (hyaluronan) are the major space-filling components of cartilage. A glycoprotein, link protein (LP; 40–48 kDa) stabilizes the aggregate by binding to both hyaluronic acid and aggrecan. In the absence of LP, aggregates are smaller (as estimated by rotary shadowing of electron micrographs) and less stable (they dissociate at pH 5) than they are in the presence of LP. The proteoglycan aggregate, including LP, is dissociated in the presence of chaotropes such as 4 M guanidine hydrochloride. On removal of the chaotrope, the complex will reassociate. This forms the basis of the isolation of LP from cartilage and has been described in detail elsewhere. Tryptic digestion of the proteoglycan aggregates results in a high molecular weight product that consists of hyaluronic acid to which is bound LP and the N-terminal globular domain of aggrecan (hyaluronic acid binding region; HABR) in a 1∶1 stoichiometry. The amino acid sequences of LP and HABR are surprisingly similar. The amino acid sequence can be divided into three domains; an N-terminal domain that falls into the immunoglobulin super-family and two C-terminal domains that are similar to each other. The DNA structure echoes this similarity, in that the major domains are reflected in three separate exons in both LP and HABR. The two C-terminal domains are largely responsible for the association with HA and are related to two recently described hyaluronate-binding proteins, CD44 and TSG-6. A variety of approaches, including analysis of the forms of LP found in vivo, rotary shadowing and analysis of the sequence in the immunoglobulin-like domain, have shed considerable light on the structure-function relationships of LP. This review describes the structure and function of LP in detail, focusing on what can be inferred from the similarity of LP, HABR and related molecules such as immunoglobulins and lymphocyte HA-receptors.
Spectroscopic constants and potential energy curves of GeH

Abstract Theoretical calculations of spectroscopic constants and potential energy curves of 13 electronic states of GeH+ are obtained. We employed complete active space MCSCF followed by CI calculations to obtain the spectroscopic constants of GeH+. The theoretical IP of the Ge atom (7.68 eV) was found to be in good agreement with an experimental value of 7.88 eV. The ground state of GeH+ was found to be a 1Σ+ state with r e = 1.576 A , ωe = 2024 cm−1, and De = 2.95 eV in excellent agreement with the known experimental results. The GeH+ ion was found to have a larger De than the neutral GeH molecule (De = 2.81 eV). Our calculations confirm the experimentally observed a3Π-X1Σ+ transition and predict other transitions which are yet to be observed.
The Transit Light Curve of an Exozodiacal Dust Cloud

Planets embedded within debris disks gravitationally perturb nearby dust and can create clumpy, azimuthally asymmetric circumstellar ring structures that rotate in lock with the planet. The Earth creates one such structure in the solar zodiacal dust cloud. In an edge-on system, the dust "clumps" periodically pass in front of the star as the planet orbits, occulting and forward-scattering starlight. In this paper, we predict the shape and magnitude of the corresponding transit signal. To do so, we model the dust distributions of collisional, steady-state exozodiacal clouds perturbed by planetary companions. We examine disks with dusty ring structures formed by the planet's resonant trapping of in-spiraling dust for a range of planet masses and semi-major axes, dust properties, and disk masses. We synthesize edge-on images of these models and calculate the transit signatures of the resonant ring structures. The transit light curves created by dusty resonant ring structures typically exhibit two broad transit minima that lead and trail the planetary transit. We find that Jupiter-mass planets embedded within disks hundreds of times denser than our zodiacal cloud can create resonant ring structures with transit depths up to ~10–4, possibly detectable with Kepler. Resonant rings produced by planets more or less massive than Jupiter produce smaller transit depths. Observations of these transit signals may provide upper limits on the degree of asymmetry in exozodiacal clouds.
Decision tree approximations of Boolean functions

Decision trees are popular representations of Boolean functions. We show that, given an alternative representation of a Boolean function f, say as a read-once branching program, one can find a decision tree T which approximates f to any desired amount of accuracy. Moreover, the size of the decision tree is at most that of the smallest decision tree which can represent f and this construction can be obtained in quasi-polynomial time. We also extend this result to the case where one has access only to a source of random evaluations of the Boolean function f instead of a complete representation. In this case, we show that a similar approximation can be obtained with any specified amount of confidence (as opposed to the absolute certainty of the former case.) This latter result implies proper PAC-learnability of decision trees under the uniform distribution without using membership queries.
Teletext-like information delivery using broadcast polling

Abstract Teletext is an information system that uses the continuous one-way broadcast of information pages as a delivery mechanism. Teletext systems are simple to operate and, because their performance is insensitive to user loads, can accomodate an unlimited number of users. This, however, is achieved at the expense of having to undertake superfluous transmissions, i.e., page broadcasts that do not satisfy any outstanding requests. In this paper, we first derive an expression representing the proportion of superfluous transmissions in a teletext system for any given cyclic sequence of page broadcasts. Next, we propose a broadcast polling information delivery scheme. This scheme insures that no superfluous transmissions take place, at the expense of requiring a two-way communication network, and incurring a polling overhead. We investigate, through the use of simulation, the response time performance of the broadcast polling scheme and how it relates to that of a teletext system.
Protein quality control in the ER: balancing the ubiquitin checkbook

Protein maturation in the endoplasmic reticulum (ER) is subject to stringent quality control. Terminally misfolded polypeptides are usually ejected into the cytoplasm and targeted for destruction by the proteasome. Ubiquitin conjugation is essential for both extraction and proteolysis. We discuss the role of the ubiquitin conjugation machinery in this pathway and focus on the role of ubiquitin ligase complexes as gatekeepers for membrane passage. We then examine the type of ubiquitin modification applied to the misfolded ER protein and the role of de-ubiquitylating enzymes in the extraction of proteins from the ER.
Entropy Profiles in the Cores of Cooling Flow Clusters of Galaxies

The X-ray properties of a relaxed cluster of galaxies are determined primarily by its gravitational potential well and the entropy distribution of its intracluster gas. That entropy distribution reflects both the accretion history of the cluster and the feedback processes that limit the condensation of intracluster gas. Here we present Chandra observations of the core entropy profiles of nine classic cooling flow clusters that appear relatively relaxed (at least outside the central 10-20 kpc) and contain intracluster gas with a cooling time less than a Hubble time. We show that those entropy profiles are remarkably similar, despite the fact that the clusters range over a factor of 3 in temperature. They typically have an entropy level of ?130 keV cm2 at 100 kpc that declines to a plateau ~10 keV cm2 at 10 kpc. Between these radii, the entropy profiles are r? with ? ? 1.0-1.3. The nonzero central entropy levels in these clusters correspond to a cooling time ~108 yr, suggesting that episodic heating on this timescale maintains the central entropy profile in a quasi-steady state. We show in an appendix that although disturbances and bubbles are visible in the central regions of these clusters, these phenomena do not strongly bias our entropy estimates.
Strict Monotonicity in Comparative Statics

Abstract Economists commonly seek to show that one variable increases in response to changes in another variable. This paper provides sufficient conditions to draw such strict monotone comparative statics conclusions in optimization problems with and without binding constraints. These results extend the lattice-theoretic results of Milgrom and Shannon [10] by imposing a stronger differential version of the single crossing property and arguing from first-order conditions. We illustrate the importance of these results through applications involving holdup problems, output decisions, optimal tax problems, and modern manufacturing. Journal of Economic Literature Classification Numbers: C61, D82.
Development of spatial coarse-to-fine processing in the visual pathway

The sequential analysis of information in a coarse-to-fine manner is a fundamental mode of processing in the visual pathway. Spatial frequency (SF) tuning, arguably the most fundamental feature of spatial vision, provides particular intuition within the coarse-to-fine framework: low spatial frequencies convey global information about an image (e.g., general orientation), while high spatial frequencies carry more detailed information (e.g., edges). In this paper, we study the development of cortical spatial frequency tuning. As feedforward input from the lateral geniculate nucleus (LGN) has been shown to have significant influence on cortical coarse-to-fine processing, we present a firing-rate based thalamocortical model which includes both feedforward and feedback components. We analyze the relationship between various model parameters (including cortical feedback strength) and responses. We confirm the importance of the antagonistic relationship between the center and surround responses in thalamic relay cell receptive fields (RFs), and further characterize how specific structural LGN RF parameters affect cortical coarse-to-fine processing. Our results also indicate that the effect of cortical feedback on spatial frequency tuning is age-dependent: in particular, cortical feedback more strongly affects coarse-to-fine processing in kittens than in adults. We use our results to propose an experimentally testable hypothesis for the function of the extensive feedback in the corticothalamic circuit.
An Algorithm for Learning Without External Supervision and Its Application to Learning Control Systems

An algorithm is proposed for the design of ``on-line'' learning controllers to control a discrete stochastic plant. The subjective probabilities of applying control actions from a finite set of allowable actions using random strategy, after any plant-environment situation (called an ``event'') is observed, are modified through the algorithm. The subjective probability for the optimal action is proved to approach one with probability one for any observed event. The optimized performance index is the conditional expectation of the instantaneous performance evaluations with respect to the observed events and the allowable actions. The algorithm is described through two transformations, T1, and T2. After the ``ordering transformation'' T1 is applied on the estimates of the performance indexes of the allowable actions, the ``learning transformation'' T2 modifies the subjective probabilities. The cases of discrete and continuous features are considered. In the latter, the Potential Function Method is employed. The algorithm is compared with a linear reinforcement schenme and computer simulation results are presented.
Herding among security analysts

The paper shows that the buy or sell recommendations of security analysts have a signi"cant positive in#uence on the recommendations of the next two analysts. This in#uence can be traced to short-lived information in the most recent revisions. In contrast, the in#uence of the prevailing consensus is not stronger if the consensus accurately forecasts subsequent stock price movements. This indicates consensus herding consistent with models in which analysts herd based on little information. The consensus also has a stronger in#uence when market conditions are favorable. The resulting poorer information aggregation could cause bull markets to be intrinsically more ‘fragilea (e.g., Bikhchandani et al., J. Political Economy 100(5) (1992) 992}1026). ( 2000 Elsevier Science S.A. All rights reserved. JEL classixcation: G11; G14; G24
Classifying Luyten stars using an optical-infrared reduced proper motion diagram

We present a V-J reduced proper-motion (RPM) diagram for stars in the new Luyten two-tenths (NLTT) catalog. In sharp contrast to the RPM diagram based on the original NLTT data, this optical-infrared RPM diagram shows distinct tracks for white dwarfs, subdwarfs, and main-sequence stars. It thereby permits the identification of white dwarf and subdwarf candidates that have a high probability of being genuine.
Advertising as Information: Matching Products to Buyers

We consider communication of quality via cheap talk and dissipative advertising expenditures, when consumers have heterogeneous tastes for quality, and price information must be acquired through costly search. For search pods, cheap talk communicates quality when fixed costs are roughly constant across quality levels, while if fixed costs vary greatly with quality, then firms having the higher fixed-cost quality level use dissipative advertising. For experience goods, quality can be communicated by cheap talk in a range where low-quality firms have greater fixed costs, and low-quality firms use dissipative advertising if their fixed costs are greater still.
25 years of technical advances in RFQ accelerators

The radio frequency quadrupole (RFQ) accelerator began as "The ion linear accelerator with space-uniform strong focusing" conceived by I.M. Kapchinskii and V.A. Teplyakov [1970]. In 1979, R.H. Stokes, K.R. Crandall, J.E. Stovall and D.A. Swenson gave this concept the name RFQ. Shortly after Valentine's Day in 1980 a telegram was sent to I.M. Kapchinskii. It stated, "The RFQ is alive and well at the Los Alamos Scientific Laboratory". Thus begins a very informative story of the early history of the development of the RFQ. By 1983, at least 15 laboratories throughout the world were working on various RFQ designs. H. Klein wrote an excellent review of a number of different RFQ structures [1983]. In the early years, there were many types of geometry considered for the RFQ, but only a few types have survived. The two cavity geometries now used in almost all RFQs are the 4-vane and 4-rod structures. The 4-vane structure is the most popular because its operating frequency range (80 to /spl sim/500 MHz) is suitable for light ions. Heavy ions require low frequencies (below 200 MHz). Because the 4-rod structure has smaller transverse dimensions than a 4-vane RFQ at the same frequency, the 4-rod RFQ is often preferred for these applications. This paper will describe how the RFQ accelerates and focuses the beam. The paper also discusses some of the important technical advances in designing and building RFQs.
Sparse Additive Functional and Kernel CCA

Canonical Correlation Analysis (CCA) is a classical tool for finding correlations among the components of two random vectors. In recent years, CCA has been widely applied to the analysis of genomic data, where it is common for researchers to perform multiple assays on a single set of patient samples. Recent work has proposed sparse variants of CCA to address the high dimensionality of such data. However, classical and sparse CCA are based on linear models, and are thus limited in their ability to find general correlations. In this paper, we present two approaches to high-dimensional nonparametric CCA, building on recent developments in high-dimensional nonparametric regression. We present estimation procedures for both approaches, and analyze their theoretical properties in the high-dimensional setting. We demonstrate the effectiveness of these procedures in discovering nonlinear correlations via extensive simulations, as well as through experiments with genomic data.
Analytical series expressions for the self- and mutual inductances of two-dimensional coils in the form of partial sectors

Pulsed power generators of the drum type utilize radial components of magnetic fields created by field coils located on a rotor to induce voltage on stator coils located at larger radii. Conventionally, two-dimensional (2-D) field analyses are used, and further, the field is expressed as a harmonic series and the fundamental part of the radial field is used for initial designs. Analytical series expressions for 2-D potentials and fields are utilized in this paper to derive analytical series expressions for the self-inductances and mutual inductances between the rotor and stator coils in the shape of partial sectors. The magnitudes of higher order terms are compared with that of the fundamental component. The effects of parameters such as the aspect ratios of conductor sections on the inductances and coupling constants are evaluated.
Do Customs Union Members Engage in More Bilateral Trade than Free-Trade Agreement Members?

This paper provides the first empirical analysis directly comparing the effects of customs unions (CUs) and free-trade agreements (FTAs) on members’ bilateral trade, while addressing the biases arising from loglinearization of the gravity model and crucial time-invariant unobservables. Since Fiorentino et al. (2007) question the popularity of CUs relative to FTAs, considering the latter to be more practical in the current trading climate, such a comparison seems especially relevant. While Baier and Bergstrand (2007) find an FTA to approximately double members’ bilateral trade after 10 years, the results of this paper find CUs to have had a much larger impact than FTAs.
Quantifying the risk of recurrence and death in stage III (FIGO 2009) endometrial cancer.

Abstract Objective Advanced endometrial cancer patients comprise a heterogeneous group. This study assessed the association of clinicopathological factors with relapse and death from endometrial cancer. Methods Eligible patients were treated for stage III (FIGO 2009) endometrial adenocarcinoma, had peritoneal cytology performed, and had no gross residual disease post-operatively. Results Of 192 patients, 59% were ≥60years old, 48% had ≥50% myometrial invasion, 71% lymphovascular invasion, 25% cervical stromal invasion, 37% adnexal involvement, and 23% positive peritoneal cytology. High-grade histology (serous, clear cell, undifferentiated, or grade 3 endometrioid) was present in 45%. Pelvic lymphadenectomy was performed in 93% and para-aortic lymphadenectomy in 73%. Adjuvant chemotherapy and/or radiation therapy was administered to 93%. At a median follow-up of 42months, the 5-year rate of relapse was 37% and of death from endometrial cancer was 30%. On multivariate analysis, both outcomes were associated with high-grade histology, positive peritoneal cytology, and deep myometrial invasion (p≤0.04). The cohort was divided into subgroups of patients with 0 (n=46), 1 (n=83), or ≥2 (n=63) of these high-risk characteristics. The 5-year relapse rate for patients with 0 risk factors was 13%, 1 risk factor was 27%, and ≥2 risk factors was 62% (p Conclusions Stratification of stage III endometrial cancer according to high-grade histology, positive peritoneal cytology, and deep myometrial invasion is useful for prognostication and may grant insight into the optimal treatment for specific subgroups of patients.
Protection Against Link Errors and Failures Using Network Coding

We propose a network-coding based scheme to protect multiple bidirectional unicast connections against adversarial errors and failures in a network. The network consists of a set of bidirectional primary path connections that carry the uncoded traffic. The end nodes of the bidirectional connections are connected by a set of shared protection paths that provide the redundancy required for protection. Such protection strategies are employed in the domain of optical networks for recovery from failures. In this work we consider the problem of simultaneous protection against adversarial errors and failures. Suppose that ne paths are corrupted by the omniscient adversary. Under our proposed protocol, the errors can be corrected at all the end nodes with 4ne protection paths. More generally, if there are ne adversarial errors and nf failures, 4ne + 2nf protection paths are sufficient. The number of protection paths only depends on the number of errors and failures being protected against and is independent of the number of unicast connections.