cssi/SciSciGPT-SciSciNet huggingface dataset:
Latino Immigration and the Low‐Skill Urban Labor Market: The Case of Atlanta

Objectives Latino immigrants continue to enter low-skilled urban labor markets across metropolitan areas in the United States. This study provides a dynamic account of the employment competition between Latino immigrant and black workers in the context of an emerging immigrant gateway: the Atlanta Metropolitan Statistical Area. Methods This study identifies occupational niches that Latino immigrants and black workers heavily concentrate for years 1990, 2000, and 2008. Occupational-level composition and wage models are also estimated to test for the impact Latino immigration might have on black workers. Results Both black workers and Latino immigrant workers became increasingly concentrated in a few occupations between 1990 and 2008. While Latino immigrants have entered several historically black occupational niches, no downward pressure on the wage growth of blacks in the same occupation is observed. Conclusions As immigrants become increasingly clustered in manual-intensive craftsmen, operative, and farm occupations, blacks gravitate toward the better-paid and language-intensive sales, clerical, and service occupations, forming a segmented low-skill labor market. The reinforcement of their respective niches also tends to create closure to the other groups and intensify within-group competition.
Dynamical excision boundaries in spectral evolutions of binary black hole spacetimes

Simulations of binary black hole systems using the Spectral Einstein Code (SpEC) are done on a computational domain that excises the regions inside the black holes. It is imperative that the excision boundaries are outflow boundaries with respect to the hyperbolic evolution equations used in the simulation. We employ a time-dependent mapping between the fixed computational frame and the inertial frame through which the black holes move. The time-dependent parameters of the mapping are adjusted throughout the simulation by a feedback control system in order to follow the motion of the black holes, to adjust the shape and size of the excision surfaces so that they remain outflow boundaries, and to prevent large distortions of the grid. We describe in detail the mappings and control systems that we use. We show how these techniques have been essential in the evolution of binary black hole systems with extreme configurations, such as large spin magnitudes and high mass ratios, especially during the merger, when apparent horizons are highly distorted and the computational domain becomes compressed. The techniques introduced here may be useful in other applications of partial differential equations that involve time-dependent mappings.
Theory of Avalanche Breakdown in InSb and InAs

We have constructed a theory of avalanche breakdown for polar semiconductors such as InSb and InAs in which the primary electron-scattering mechanism is polar-optical-mode scattering. Because of the anisotropy of polar scattering, previous theories of avalanche breakdown involving the assumptions of an isotropic scattering probability and/or a nearly isotropic electron distribution should not be appropriate for polar semiconductors. We have assumed a very anisotropic electron distribution which is narrowly drawn out in the direction of the electric field. We also distinguish between small- and large-angle scattering, since for polar scattering, the probability of scattering to a state close to the initial state is much greater than the probability for scattering through a large angle, although the latter process results in a greater loss of energy, since it places the electron in a state in which it is decelerated by the field. The electron distribution function is obtained analytically, and from it the pair-generation rate and electron drift velocity are calculated for InSb and InAs. The pair-generation rate for InSb is obtained using the ionicity which best fits the low-field-mobility data and a hyperbolic conduction band, and it agrees very well with experimental data on the generation rate in InSb. The calculated drift velocity at fields above 200 V/cm is also in good agreement with the drift-velocity measurements by Glicksman and Hicenbothem, showing that the electron distribution is, indeed, highly anisotropic.
An analytical model for transport from quasi-steady and periodic accelerations on spacecraft

Abstract A simplified analytical model of the coupled flow, heat, and mass transfer in the core region of a rectangular, low aspect ratio flow channel has been developed that can predict the magnitude of the flows and the convective transport resulting from small transverse steady and periodic accelerations typically associated with manned spacecraft. The effects of stabilizing and destabilizing axial gradients are determined for both steady and time dependent transverse accelerations. It is found that the time average of the heat and mass transport scales as the square of the Grashof number and is inversely proportional to the 7/2 power of the frequency. Furthermore, it is shown that the effects of multi-frequency disturbances are additive making it possible to integrate over a properly weighted power spectral density spectrum in order to obtain the net flow and transport. The relative transport from steady and periodic accelerations was estimated for the types of experiments germane to this model that are typically carried out in microgravity. It was also found that a stabilizing axial gradient has little effect on the flows and transport at higher frequencies, suggesting the possibility of testing the g-jitter predictions on the ground. Finally it is shown that the start-up transients can have profoundly different effects depending on the phase of the acceleration at the starting time.
The Sasaki Join, Hamiltonian 2-forms, and Constant Scalar Curvature

We describe a general procedure for constructing new explicit Sasaki metrics of constant scalar curvature (CSC), including Sasaki–Einstein metrics, from old ones. We begin by taking the join of a regular Sasaki manifold of dimension \(2n+1\) and constant scalar curvature with a weighted Sasakian 3-sphere. Then by deforming in the Sasaki cone we obtain CSC Sasaki metrics on compact Sasaki manifolds \(M_{l_1,l_2,\mathbf{w}}\) of dimension \(2n+3\) which depend on four integer parameters \(l_1,l_2,w_1,w_2\). Most of the CSC Sasaki metrics are irregular. We give examples which show that the CSC rays are often not unique on the underlying fixed strictly pseudoconvex CR manifold. Moreover, it is shown that when the first Chern class of the contact bundle vanishes, there is a two-dimensional subcone of Sasaki–Ricci solitons in the Sasaki cone, and a unique Sasaki–Einstein metric in each of the two-dimensional subcones.
Hydrogen adsorption in dehydrated variants of the cyano-bridged framework compounds A2Zn3[Fe(CN)6]2·xH2O (A = H, Li, Na, K, Rb)

The impact of coordinatively-unsaturated alkali-metal ions on hydrogen adsorption is studied in dehydrated variants of the compounds A(2)Zn(3)[Fe(CN)(6)](2).xH(2)O (A = H, Li, Na, K, Rb), revealing maximum adsorption enthalpies that vary from 7.7 kJ mol(-1) for A = Na to 9.0 kJ mol(-1) for A = K.
Numerical Simulation of an Accelerator Injector

Accelerator injector designs have been evaluated using two computer codes. The first code self consistently follows relativistic particles in two dimensions. Fields are obtained in the Darwin model which includes inductive effects. This code is used to study cathode emission and acceleration to full injector voltage. The second code transports a fixed segment of a beam along the remainder of the beam line. Using these two codes the effects of electrode configuration on emittance, beam quality and beam transport have been studied.
A ‘long march’ perspective on tobacco use in Canada

. In this paper we present a model of tobacco demand in Canada, with a view to establishing if price and tax policy on the one hand or educational, regulatory, and demographic influences on the other have been primarily responsible for the substantial drop in consumption since 1980. We address some methodological and econometric issues that have escaped the attention of some analysts to this point. Using data for the period 1972–2000, we find that non-price developments have had a strong deterrent effect and that the price elasticity of demand is now lower than even the recently obtained low estimates propose. These findings have strong public policy content. JEL Classification: I12, C13, C22 Une perspective de «longue haleine» sur l’usage du tabac au Canada. Dans ce memoire, on presente un modele de la demande de tabac au Canada en vue d’etablir laquelle des deux strategies – d’une part, la politique de prix et d’imposition de taxes, et d’autre part, les influences de l’education, de la reglementation ainsi que les changements demographiques – a ete davantage responsable de la chute importante dans la consommation du tabac depuis 1980. Le texte examine certains problemes methodologiques et econometriques qui ont jusqu’ici echappea l’attention des analystes. A l’aide de donnees pour la periode 1972–2000, on montre que les facteurs qui n’ont rien a voir avec le prix ont eu un fort effet dissuasif, et que l’elasticite de la demande par rapport au prix est maintenant plus faible que les faibles elasticites suggerees par certaines etudes recentes. Ces resultats ont une grande importance pour la politique publique.
On Loop Equations in KdV Exactly Solvable String Theory

The non-perturbative behavior of macroscopic loop amplitudes in the exactly solvable string theories based on the KdV hierarchies is considered. Loop equations are presented for the real non-perturbative solutions living on the spectral half-line, allowed by the most general string equation , where generates scale transformations. In general the end of the half-line (the 'wall') is a non-perturbative parameter whose role is that of boundary cosmological constant. The properties are compared with the perturbative behavior and solutions of [P, Q]=1. Detailed arguments are given for the (2,2m-1) models while generalization to the other (p,q) minimal models and c=1 is briefly addressed.
Flight Test Studies of the Formation and Dissipation of Trailing Vortices

A flight test program has been conducted to measure experimentally parameters which describe the characteristics of vortex behavior and their instability. Three basic atmospheric flight conditions were investigated: steady level flight in calm air, steady level flight in light gusting air and light winds, and unsteady flight produced by control surface oscillations in calm air. A DeHavilland Beaver DHC-2 airplane and a Beechcraft T-34B airplane were used in the investigation. Smoke grenades were located near the wing tips of each airplane such that the vortices could be seeded with smoke and thus made visible. This made it possible to photograph the vortices and make measurements from the photographs obtained. The experimental results show wavelengths of vortex instabilities, dissipation time of trailing vortices, effects of atmospheric current or gust, and the effect of control surface oscillation. These results provide additional experimental verification of the existence of vortex wake instability predicted by theory and show that small oscillations in pitch at a critical frequency accelerate the dissipation of high-intensity vortices.
On the Role of Confidentiality and Deadlines in Bilateral Negotiations

Abstract The preference between public and private negotiations for a buyer who sequentially visits two sellers is examined. It is shown that the buyer (weakly) prefers private negotiations so as to create strategic uncertainty about the trade history. With substitute goods, such uncertainty is valuable only when price offers have short deadlines that prevent a head-to-head competition. With complementary goods, strategic uncertainty is valuable to the extent that price coordination becomes a concern for sellers, which is likely to be the case when sellers possess high bargaining powers; their price offers have short deadlines; and/or goods are weak complements. Sellersʼ strategic deadline choices as well as their incentives to disclose information about negotiations are also investigated.
Preoperative use of 3D volume rendering to demonstrate renal tumors and renal anatomy.

Abstract With increased us of computed tomography (CT) and abdominal ultrasonography, the indications for nephron-sparing surgery are also increasing. Triphasic helical CT and three-dimensional (3D) volume rendering can be combined into a single noninvasive test to delineate renal tumors and normal and complex renal anatomy prior to nephron-sparing surgery. This combination technique has provided accurate and very useful for both preoperative and intraoperative planning by demonstrating renal position, tumor location and depth of tumor extension into the kidney, relationship of the tumor to the collecting system, and renal vascular anatomy. Knowledge of the position of the kidney relative to the lower rib cage, iliac crest, and spine helps in planning the initial surgical incision. By depicting tumor location and depth of extension, helical CT with 3D volume rendering helps ensure complete tumor excision and conservation of adjacent normal renal parenchyma. Depiction of the relationship of the tumor to the collecting system helps anticipate further tumor extension and minimize postoperative complications. Identification of normal renal vasculature and anatomic variants can help minimize ischemic injury and intraoperative bleeding. Radiologists should be familiar with current indications for nephron-sparing surgery and understand what information is required prior to surgery. The authors underscore the value of helical CT with 3-dimensional imaging in the approach to nephron-sparing surgery for localized renal cancers. The authors suggest, and I agree, that this technique can markedly reduce the need for invasive arteriographic imaging in these patients. The ability of this technique to identify the renal vasculature may prove particularly useful in cases where difficult partial nephrectomy is contemplated. Robert Flanigan, M.D.
The SENSE-Isomorphism Theoretical Image Voxel Estimation (SENSE-ITIVE) Model for Reconstruction and Observing Statistical Properties of Reconstruction Operators

The acquisition of sub-sampled data from an array of receiver coils has become a common means of reducing data acquisition time in MRI. Of the various techniques used in parallel MRI, SENSitivity Encoding (SENSE) is one of the most common, making use of a complex-valued weighted least squares estimation to unfold the aliased images. It was recently shown in Bruce et al. [Magn. Reson. Imag. 29(2011):1267-1287] that when the SENSE model is represented in terms of a real-valued isomorphism,it assumes a skew-symmetric covariance between receiver coils, as well as an identity covariance structure between voxels. In this manuscript, we show that not only is the skew-symmetric coil covariance unlike that of real data, but the estimated covariance structure between voxels over a time series of experimental data is not an identity matrix. As such, a new model, entitled SENSE-ITIVE, is described with both revised coil and voxel covariance structures. Both the SENSE and SENSE-ITIVE models are represented in terms of real-valued isomorphisms, allowing for a statistical analysis of reconstructed voxel means, variances, and correlations resulting from the use of different coil and voxel covariance structures used in the reconstruction processes to be conducted. It is shown through both theoretical and experimental illustrations that the miss-specification of the coil and voxel covariance structures in the SENSE model results in a lower standard deviation in each voxel of the reconstructed images, and thus an artificial increase in SNR, compared to the standard deviation and SNR of the SENSE-ITIVE model where both the coil and voxel covariances are appropriately accounted for. It is also shown that there are differences in the correlations induced by the reconstruction operations of both models, and consequently there are differences in the correlations estimated throughout the course of reconstructed time series. These differences in correlations could result in meaningful differences in interpretation of results.
Measurement of high-field electron transport in silicon carbide

We report recent measurements of the drift velocity of electrons parallel to the basal plane in 6H and 4H silicon carbide (SiC) as a function of applied electric field. The dependence of the low field mobility and saturated drift velocity on temperature are also reported. The saturated drift velocities at room temperature are approximately 1.9/spl times/10/sup 7/ cm/s in 6H-SiC and 2.2/spl times/10/sup 7/ cm/s in 4H-SiC.
Polynomial algorithms for estimating network reliability

We consider the problem of calculating the best possible bounds on the reliability of a system given limited information about the joint density function of its components. We show that a polynomial algorithm for this problem exists iff such an algorithm exists for a certain related problem of minimizing a linear objective function over a clutter. We give numerous examples of network as well as other problems for which the algorithm runs in polynomial time. We also use our construction to prove NP-hardness for others.
Distribution of Trace Elements in the Environment and the Occurrence of Heart Disease in Georgia

The concentrations of certain chemical elements in native plants, garden vegetables, and soils were studied in two areas of Georgia, each made up of nine counties, that have greatly different heart disease mortality rates. The soils of the two areas were found to be geochemically distinct. The greater amounts of trace elements in soils occur in the counties that have the lower death rates, but the abundances of trace elements in trees and vegetables do not correspond closely to the abundances in the soils. The trace elements in soils, however, may have entered the human food chain in water, in other food plants, and in meat and milk that were not sampled in this study. If geochemical differences between the soils of the high-death-rate area and the low-death-rate area do, in fact, have a causal relationship to death from cardiovascular diseases, the cause would appear to be a deficiency, rather than an excess, of the elements that were studied.
Preemptive routing in ad hoc networks

Routing in ad hoc networks is a challenging problem because nodes are mobile and links are continuously being created and broken. Existing on-demand ad hoc routing algorithms initiate route discovery only after a path breaks, incurring a significant cost in detecting the disconnection and establishing a new route. In this work, we investigate adding proactive route selection and maintenance to on-demand ad hoc routing algorithms. More specifically, when a path is likely to be broken, a warning is sent to the source indicating the likelihood of a disconnection. The source can then initiate path discovery early, potentially avoiding the disconnection altogether. A path is considered likely to break when the received packet power becomes close to the minimum detectable power (other approaches are possible). Care must be taken to avoid initiating false route warnings due to fluctuations in received power caused by fading, multipath effects and similar random transient phenomena. Experiments demonstrate that adding proactive route selection and maintenance to DSR and AODV (on-demand ad hoc routing protocols) significantly reduces the number of broken paths, with a small increase in protocol overhead. Packet latency and jitter go down in most cases. Because preemptive routing reduces the number of broken paths, it also has a secondary effect on TCP performance--unnecessary congestion handling measures are avoided. This is observed for TCP traffic under different traffic patterns (telnet, ftp and http). Additionally, we outline some problems in TCP performance in ad hoc environments.
Competitive Equilibria With Incomplete Markets and Endogenous Bankruptcy

This is the publisher's version, also available electronically from http://dx.doi.org/ 10.2202/1534-5971.1060.
A statistical boundary layer model for the mantle D″ region

[1] The D″ region above the core-mantle boundary (CMB) plays critical roles in the dynamics of both the mantle and the core; however, the complexity of this region observed over a broad range of spatial scales defies simple interpretations as either purely thermal or purely chemical heterogeneity. Here, we formulate a 1-D, time-dependent boundary layer model for the D″ region, which provides statistical properties of the dynamics and seismic heterogeneity, by coupling thermal, chemical, and phase (TCP) variability in the layer. We assume a Gaussian-like time-dependent mantle flow, compositional stratification due to variations in iron content, heat flow variations because of changes in the local temperature gradient, and a postperovskite (PPV) phase transformation. We compute a range of TCP boundary layer model cases that are consistent with the observed seismic shear wave velocity heterogeneity in the region 50–300 km above the CMB. These results imply an average CMB heat flow near 13 TW with ±3 TW variations, CMB temperature of 4000 K, a large positive PPV Clapeyron slope, and an average heat transport of about 3 TW associated with deep mantle plumes.
Hydrogen bonding Part 59. NMR study of N,N,N-trimethyl-1-adamantylammonium, trimethyl-i-pentylammonium, and tetra-i-pentylammonium ions; an explanation for the anomalous hydration behavior of N,N,N-trimethyl-1-adamantylammonium ion salts

Abstract The halide and hydroxide salts of the N,N,N-trimethyl-1-adamantylammonium ion have hydration behaviors which are different from the common patterns shown by all other quaternary ammonium ion halide and hydroxide salts we have studied. These differences include formation of higher iodide and bromide hydrates, failure to form halide monohydrates, and the existence of unusual molecular ions with three-center covalent hydrogen bonding in the lower fluoride and hydroxide hydrates. The 1H NMR spectrum of N,N,N-trimethyl-1-adamantylammonium ion is not consistent with that expected from application of conventional chemical shift rules. Comparison with the model compounds trimethyl-i-pentylammonium and tetra-i-pentylammonium ions, which have similar CH arrangements but lack the tricyclic cage, demonstrate that through-cage interactions spread positive charge over the whole structure of the N,N,N-trimethyl-l-adamantylammonium ion. The diffusely charged nature of the ion is correlated with the observed anomalous hydration behavior of its salts.
Cosmology, Mach’s principle and relativity

The significance of Mach’s principle (and the implicit relativity principle) for field theory is discussed, also the significance of zero-mass boson fields for the geometry of the physical space. The significance of such fields for Mach’s principle within the framework of cosmology is also discussed. It is suggested that the distant matter of the universe generates one or two zero-mass boson fields, very likely a tensor field and perhaps a scalar, and that each of these fields propagates, carrying into the laboratory a quasistatic influence having its origin primarily in the distant matter of the universe. The observable effects of these “Machian fields” are described.
Correlators of local operators and 1/8 BPS Wilson loops on S 2 from 2d YM and matrix models

We propose that, in $$ \mathcal{N} = 4 $$ Super Yang-Mills theory, correlation functions of certain 1/8 BPS Wilson loops and local operators inserted on a S 2 in space-time may be computed in terms of analogous observables in the “zero-instanton” sector of 2d Yang-Mills theory. The Wilson loops are mapped to the standard Wilson loops of the 2d theory, as recently conjectured, while the local operators are mapped to powers of the 2d field strength. We give several perturbative checks of the correspondence, and derive from 2d Yang-Mills a two-matrix model for the correlator of a local operator and a Wilson loop of arbitrary shape. We show that the strong coupling planar limit of the two-matrix model precisely agrees with a string theory calculation in AdS 5×S 5
Analytic approach to the stability of standing accretion shocks : Application to core-collapse supernovae

We explore an analytic model of the accretion shock in the postbounce phase of a core-collapse supernova explosion. We find growing oscillations of the shock in the l = 1 and 2 modes, in agreement with a variety of existing numerical simulations. For modest values of the ratio of the outer accretion shock to that of the inner boundary to the shocked flow, the instability appears to derive from the growth of trapped sound waves, whereas at higher values, postshock advection clearly plays a role. Thus, the model described here may relate to the different mechanisms of instability recently advocated by Blondin & Mezzacappa and by Foglizzo and collaborators.
EFFECTS OF SAMPLE-SPECIFIC VARIATIONS AND FLUCTUATIONS OF THERMAL OCCUPANCY ON FLUCTUATIONS OF THERMODYNAMIC QUANTITIES

Standard results for the fluctuations of thermodynamic quantities are derived under the assumption of sampling identical systems that are in different, not fully equilibrated states. These results apply to fluctuations with time in a particular macroscopic body and can be traced to the fluctuations of thermal occupancy. When many identically prepared — but not identical — systems are studied, mesoscopic fluctuations due to variations from sample-to-sample contribute to the fluctuations of thermodynamic quantities. We study the combined effect of mesoscopic fluctuations and fluctuations of thermal occupancy. In particular, we evaluate the total particle number and specific heat fluctuations in a two-dimensional, noninteracting electron gas in classically integrable and chaotic circumstances.
Formation of optical bullets in laser-driven plasma bubble accelerators

We visualize laser-generated electron density “bubbles” by observing “bullets” of light that they trap, focus and compress from co-propagating probe pulses. We correlate these bullets with relativistic electrons that the bubble captured and accelerated.
Development of a Cutting Direction and Sensor Orientation Independent Monitoring Technique for End-Milling

In the authors' previous work, univariate models were fit to acceleration data to predict impending tool failure. Numerous end-milling life tests, conducted under a wide variety of cutting conditions, demonstrated that the method could consistently warn of impending failure between 6 inches (15 cm) and 8 inches (20 cm) prior to the actual event. This paper presents an improved method that increases the warning time and allows the technique to function independent of the cutting direction or sensor orientation. Using multivariate autoregressive models fit to tri-axial accelerometer signals, monitoring indices are developed, verified and the results are compared with those from the univariate models. The multivariate models detected impending failure 30 inches (76 cm) prior to its occurrence, 23.5 inches (60 cm) earlier than with the univariate models. Furthermore, the multivariate models are able to monitor the condition of the tool, regardless of the cutting direction or sensor orientation.
Nonlinear resonant three-wave interactions of Alfvén waves

Abstract We will consider the nonlinear resonant three-wave interactions of Alfven waves. By using both analytic developments and numerical calculations, further insights into the nature of these nonlinear wave interactions are given. The wave interactions are shown to be non-explosive and to lead to a periodic energy exchange.
Virtual Bronchoscopy: Relationships of Virtual Reality Endobronchial Simulations to Actual Bronchoscopic Findings

Advances in computer technology have permitted development of virtual reality images of the tracheobronchial tree using data sets derived from helical CT of the chest. To determine the relevance of these images to actual bronchoscopic findings, we compared "virtual bronchoscopy" images with videotaped bronchoscopy results in 20 patients who had undergone both helical chest CT and fiberoptic bronchoscopy during clinical evaluation of their thoracic problems. Suboptimal endobronchial simulations in ten patients identified important, readily-addressed technical requirements for this imaging procedure. In the ten patients with technically suitable renderings of the airway, virtual bronchoscopy simulations accurately demonstrated endobronchial obstructions by tumor in five, airway distortion and/or ectasia in four, and accessory bronchi in another. These preliminary observations suggest that virtual bronchoscopy simulations accurately represent major endobronchial anatomic findings. This technique may have a role in prebronchoscopy planning, endoscopy training, and/or endobronchial therapy, and merits further study.
Some novel quinone-type dyes containing naphthoquinone and related fused ring systems

A variety of 1,4-thiazines, thiazoles, 1,4-dithines and 2,2′-bithiazoles containing fused naphthoquinone and related rings have been prepared. The compounds include several novel chromophoric heterocyclic system and their visible absorption spectra are discussed.
Propagation functions in pseudoparticle fields

The Green's functions for massless spinor and vector particles propagating in a self-dual but otherwise arbitrary non-Abelian gauge field are shown to be completely determined by the corrresponding Green's functions of scalar particles. Simple, explicit algebraic expressions are constructed for the scalar Green's functions of isospin-\textonehalf{} and isospin-1 particles in the self-dual field of a configuration of $n$ pseudoparticles described by $5n$ arbitrary parameters.
Gaussian Process Single-Index Models as Emulators for Computer Experiments.

A single-index model (SIM) provides for parsimonious multidimensional nonlinear regression by combining parametric (linear) projection with univariate nonparametric (nonlinear) regression models. We show that a particular Gaussian process (GP) formulation is simple to work with and ideal as an emulator for some types of computer experiment as it can outperform the canonical separable GP regression model commonly used in this setting. Our contribution focuses on drastically simplifying, reinterpreting, and then generalizing a recently proposed fully Bayesian GP-SIM combination. Favorable performance is illustrated on synthetic data and a real-data computer experiment. Two R packages, both released on CRAN, have been augmented to facilitate inference under our proposed model(s).
Metabolic network modelling: Including stochastic effects

We propose to model the dynamics of metabolic networks from a systems biology point of view by four dynamical structure elements: potential function, translocation matrix, degradation matrix, and stochastic force. These four elements are balanced to determine the network dynamics, which gives arise to a special stochastic differential equation supplemented by a relationship between the stochastic force and the degradation matrix. Important network behaviors can be obtained from the potential function without explicitly solving for the time-dependent solution. The existence of such a potential function suggests a global optimization principle. The existence stochastic force corresponds naturally to the hierarchical structure in metabolic networks. We provide theoretical evidences to justify our proposal by discussing its connections to others large-scale biochemical systems approaches, such as the network thermodynamics theory, biochemical systems theory, metabolic control analysis, and flux balance analysis. Experimental data displaying stochasticity which carries important biological information are also pointed out.
Design and flight testing of digital direct side-force control laws

Three-input/three-output command augmentation control laws have been designed and tested in flight using Princeton's Variable-Response Research Aircraft. Controllers were based upon algebraic model-following, a fast and efficient method of direct digital synthesis for advanced control modes. Pilot opinions of several command modes and controller-to-command pairings are presented in this paper. Flat turns, lateral translation, and roll control were investigated. Of the command modes tested, foot pedals-to-yaw rate, lateral stick-to-roll rate, and thumb lever-to-sideslip angle provided the best overall ratings.
To vote or not to vote: what is the quota?

Abstract The observation of a new type of perverse behavior of voting rules—Brams and Fishburn's “no-show paradox”—led Moulin to introduce the Participation Axiom (PA). It requires that an elector's failure to vote should never result in the election of a candidate whom he/she prefers to the one elected if he/she votes sincerely. The present paper examines PA in the context of Condorcet-type conditions. For a given quota q, 1 2 ≤q≤1 , the q-Core Condition (qCC) requires that whenever there exists a candidate such that no other candidate is preferred to him/her by a fraction of q or more of the voters, the elected candidate should have this property. It is shown here that PA and qCC are consistent iff q≥ (m−1) m or m ≤3, where m is the number of candidates. This essentially confirms a conjecture of Moulin and extends his original result for q= 1 2 .
CATALYTIC IRON-MEDIATED ENEDIENE CARBOCYCLIZATIONS : THE ENANTIOSELECTIVE SYNTHESIS OF A HOMOLOGUE OF THE ALKALOID (-)-PROTOEMETINOL

Abstract The efficient enantioselective synthesis of the benzoquinolizidine 2 highlights the utility of the stereoselective iron-catalyzed cyclization of enedienes and affords the opportunity to prepare analogues of protoemetinol, psychotrine, and related natural products.
Double stereodifferentiating crotylation reactions with α-amino aldehydes: Asymmetric synthesis of vicinal amino alcohol synthons

The sense and level of 1,2-asymmetric induction have been evaluated in the BF3·OEt2 promoted addition of (E)-crotylsilanes (R)-1 and (S)-1 to α-amino aldehydes 2a through 2d. The sense of carbonyl diastereoface selectivity was shown to be dependent of the chirality of the silane reagent.
Stochastic Switching Games and Duopolistic Competition in Emissions Markets

We study optimal behavior of energy producers under a CO$_2$ emission abatement program. We focus on a two-player discrete-time model where each producer is sequentially optimizing her emission and production schedules. The game-theoretic aspect is captured through a reduced-form price-impact model for the CO$_2$ allowance price. Such duopolistic competition results in a new type of non-zero-sum stochastic switching game with finite horizon. Existence of game Nash equilibria is established through generalization to randomized switching strategies. No uniqueness is possible, and we therefore consider a variety of correlated equilibrium mechanisms. We prove existence of correlated equilibrium points in switching games and give a recursive description of equilibrium game values. A simulation-based algorithm to solve for the game values is constructed, and a numerical example is presented.
On the Lagrangian Dynamics of Atmospheric Zonal Jets and the Permeability of the Stratospheric Polar Vortex

The Lagrangian dynamics of zonal jets in the atmosphere are considered, with particular attention paid to explaining why, under commonly encountered conditions, zonal jets serve as barriers to meridional transport. The velocity field is assumed to be two-dimensional and incompressible, and composed of a steady zonal flow with an isolated maximum (a zonal jet) on which two or more traveling Rossby waves are superimposed. The associated Lagrangian motion is studied with the aid of the Kolmogorov–Arnold–Moser (KAM) theory, including nontrivial extensions of well-known results. These extensions include applicability of the theory when the usual statements of nondegeneracy are violated, and applicability of the theory to multiply periodic systems, including the absence of Arnold diffusion in such systems. These results, together with numerical simulations based on a model system, provide an explanation of the mechanism by which zonal jets serve as barriers to the meridional transport of passive tracers under commonly encountered conditions. Causes for the breakdown of such a barrier are discussed. It is argued that a barrier of this type accounts for the sharp boundary of the Antarctic ozone hole at the perimeter of the stratospheric polar vortex in the austral spring.
The Effect of End-of-Life Discussions on Perceived Quality of Care and Health Status Among Patients With COPD

Background Despite strong preferences for discussions about end-of-life care, patients with COPD do not often have these discussions with their providers. Our objective was to determine whether patients who reported having end-of-life discussions also reported higher perceived markers of quality of care and health status. Methods A cross-sectional study of data collected at baseline for a trial to improve the occurrence and quality of end-of-life communication in patients with COPD was conducted. The primary exposure was self-reported acknowledgment of having discussions about end-of-life planning with their physicians. The primary outcome measures were patient-reported quality of care and satisfaction with care, which were dichotomized as best imaginable quality of care vs other ratings of quality and highest satisfaction vs other ratings of satisfaction. We adjusted for confounding factors, including patient and provider characteristics, using logistic regression clustered by provider. Results Three hundred seventy-six patients were enrolled, of whom 55 (14.6%) reported having end-of-life discussions. Individuals who reported having end-of-life discussions with their physicians were significantly more likely to rate their quality of care as the best imaginable (OR, 2.07; 95% CI, 1.05–4.09) and to be very satisfied with their medical care (OR, 1.98; 95% CI, 1.10–3.55). Discussions were more likely to have occurred among patients with worse health status as measured by St. George Respiratory Questionnaire total and impact scores. Conclusions Patients who reported having end-of-life care discussions with their physicians had higher perceived quality of care and satisfaction with their physicians. Discussing end-of-life care with patients who have COPD may improve their perceived overall quality of and satisfaction with care.
The Role of Privacy Risk in IT Acceptance: An Empirical Study

Privacy risk is increasingly entering the public consciousness when using information technologies. To gain insight into the role of risk in the technology adoption process, we studied the use of information systems for student registration and schedule management at a major U.S. university. We further extended the technology acceptance model (TAM) to include perceptual measures of privacy risk harm and privacy risk likelihood, which apply to the extended model and predict studentsâ€™ intentions to use technology. Privacy risk factors are found to negatively influence intention and contribute substantially to model predictiveness. This finding underlines the growing importance of privacy risk in the use of information technology.
Calculations of the stability of some axisymmetric flows proposed as a model of vortex breakdown

The term 'vortex breakdown' refers to the abrupt and drastic changes of structure that can sometimes occur in swirling flows. It has been conjectured that the 'bubble' type of breakdown can be viewed as an axisymmetric wave traveling upstream in a primarily columnar vortex flow. In this scenario the wave's upstream progress is impeded only when it reaches a critical amplitude and it loses stability to some nonaxisymmetric disturbance. We will investigate the stability of some axisymmetric wavy flows, which model vortex breakdown, to three-dimensional disturbances viewing the amplitude of the wave as a bifurcation parameter. We will also look at the stability of a set of related, columnar vortex flows which are constructed by taking the two-dimensional flow at a single axial location and extending it throughout the domain without variation. The method of our investigation will be to expand the perturbation velocity in a series of divergence free vectors which ensures that the continuity equation for the incompressible fluid is satisfied exactly by the computed velocity field. Projections of the stability equation onto the space of inviscid vector fields eliminates the pressure term from the equation and reduces the differential eigen problem to a generalized matrix eigen problem. Results are presented both for the one-dimensional, columnar vortex flows and also for the wavy 'bubble' flows.
The Evolution of Early-Type Field Galaxies Selected from a NICMOS Map of the Hubble Deep Field North

The redshift distribution of well-defined samples of distant early-type galaxies offers a means to test the predictions of monolithic and hierarchical galaxy formation scenarios. NICMOS maps of the entire Hubble Deep Field North in the F110W and F160W filters, when combined with the available WFPC2 data, allow us to calculate photometric redshifts and determine the morphological appearance of galaxies at rest-frame optical wavelengths out to z {approx} 2.5. Here we report results for two subsamples of early-type galaxies, defined primarily by their morphologies in the F160W band, which were selected from the NICMOS data down to H{sub 160AB} 1.5. A (V/V{sub max}) test confirms this result. When the effects of passive luminosity evolution are included in the calculation, the mean value of Vmax for the primary sample is 0.22 {+-} 0.05, andmore » 0.31 {+-} 0.04 for all the early-types. A hierarchical formation model better matches the redshift distribution of the HDF-N early-types at z > 1.5, but still does not adequately describe the observed early-types. The hierarchical model predicts significantly bluer colors on average than the observed early-type colors, and underpredicts the observed number of early-types at z {approx} 2. Though the observed redshift distribution of the early-type galaxies in our HDF-NICMOS sample is better matched by a hierarchical galaxy formation model, the reliability of this conclusion is tempered by the restricted sampling area and relatively small number of early-type galaxies selected by our methods. For example, our results may be biased by the way the HDF-N appears to intersect a large scale structure at z {approx} 1. The results of our study underscore the need for high resolution imaging surveys that cover greater area to similar depth with similar quality photometry and wavelength coverage. Though similar in appearance in the H{sub 160} data, the primary and secondary samples are otherwise rather different. The primary sample is redder, more luminous, larger, and apparently more massive than the secondary sample. Furthermore the secondary sample shows morphologies in the optical WFPC2 images that are more often similar to late-type galaxies than is the case for the primary sample. The bluer secondary sample of early-types have a star formation history which can be approximated by a Bruzual & Charlot {tau} model, or by a galaxy formed at high redshift with a small, recent starburst. Given the differences in their apparent stellar masses and current luminosities, it would seem unlikely that the secondary sample could evolve into galaxies of the primary sample.« less
Amorphous Semiconductor Switching

Professor Henisch considers amorphous semiconductor switching in the light of the fourth international conference on amorphous and liquid semiconductors held at Ann Arbor in August 1971.
A3 domain residue Glu1829 contributes to A2 subunit retention in factor VIIIa.

Summary. Background: Factor VIII (FVIII) is activated by thrombin to the labile FVIIIa, a heterotrimer of A1, A2 and A3C1C2 subunits, which serves as a cofactor for FIXa. A primary reason for the instability of FVIIIa is the tendency for the A2 subunit to dissociate from FVIIIa leading to an inactive cofactor and consequent loss of FXase activity. Objective: Based on our finding of low-specific activity and a fast decay rate for a FVIII point mutation of Glu1829 to Ala (E1829A), we examined whether residue Glu1829 in the A3 subunit is important for A2 subunit retention. Results: The rate of activity decay of E1829A was ∼fourteenfold faster than wild-type (wt) FVIIIa and this rate was reduced in the presence of added A2 subunit. Specific activity values for E1829A measured by one-stage and two-stage assays were ∼14% and ∼11%, respectively, compared with wt FVIII. Binding affinity for the A1 subunit to E1829A-A3C1C2 was comparable to wt A3C1C2 (Kd = 20.1 ± 3.4 nm for E1829A, 15.3 ± 3.7 nm for wt), whereas A2 subunit affinity for the A1/A3C1C2 dimer forms was reduced by ∼3.6-fold as a result of the mutation (Kd = 526 ± 107 nm for E1829A, 144 ± 21 nm for wt). Conclusion: As modeling data suggest that Glu1829 is located at the A2-A3 domain interface these results are consistent with Glu1829 contributing to the interactions involved with A2 subunit retention in FVIIIa.
An experiment to distinguish between de Broglie-Bohm and standard quantum mechanics

An experiment is suggested that is capable of distinguishing between the de Broglie-Bohm theory and standard quantum mechanics.
Optimal thickness distributions of aeroelastic flapping shells

Abstract The severe weight limitations of flapping wing micro air vehicles necessitates the use of thin flexible wings, which in turn requires an aeroelastic modeling tool for proper numerical characterization. Furthermore, due to the unconventional nature of these vehicles, wing design guidelines for thrust and/or power considerations are not generally available; numerical design optimization then becomes a valuable tool. This work couples a nonlinear shell model to an unsteady vortex lattice solver, and then computes analytical design gradients: the derivative of aerodynamic force/power quantities with respect to a large vector of thickness variables. Gradient-based optimization is then used to locate the wing structure that maximizes the thrust, or minimizes the power under a thrust constraint, for a variety of shell boundary conditions. Changes in the topological features of the optimal wing thicknesses highlight important aeroelastic interactions that can be exploited for efficient flapping wings.
Variational integrators for almost-integrable systems

We construct several variational integrators—integrators based on a discrete variational principle—for systems with Lagrangians of the form L = LA + eLB, with \({\varepsilon \ll 1}\), where LA describes an integrable system. These integrators exploit that \({\varepsilon \ll 1}\) to increase their accuracy by constructing discrete Lagrangians based on the assumption that the integrator trajectory is close to that of the integrable system. Several of the integrators we present are equivalent to well-known symplectic integrators for the equivalent perturbed Hamiltonian systems, but their construction and error analysis is significantly simpler in the variational framework. One novel method we present, involving a weighted time-averaging of the perturbing terms, removes all errors from the integration at \({\fancyscript{O} {(\varepsilon)}}\). This last method is implicit, and involves evaluating a potentially expensive time-integral, but for some systems and some error tolerances it can significantly outperform traditional simulation methods.
Design criteria and eigensequence plots for satellite-computed tomography

The use of the degrees of freedom for signal is proposed as a design criteria for comparing different designs for satellite and other measuring systems. It is also proposed that certain eigensequence plots be examined at the design stage along with appropriate estimates of the parameter lambda playing the role of noise to signal ratio. The degrees of freedom for signal and the eigensequence plots may be determined using prior information in the spectral domain which is presently available along with a description of the system, and simulated data for estimating lambda. This work extends the 1972 work of Weinreb and Crosby.