cssi/SciSciGPT-SciSciNet huggingface dataset:
Virtual evolution for visual search in natural images results in behavioral receptive fields with inhibitory surrounds

The neural mechanisms driving perception and saccades during search use information about the target but are also based on an inhibitory surround not present in the target luminance profile (e.g., Eckstein et al., 2007). Here, we ask whether these inhibitory surrounds might reflect a strategy that the brain has adapted to optimize the search for targets in natural scenes. To test this hypothesis, we sought to estimate the best linear template (behavioral receptive field), built from linear combinations of Gabor channels representing V1 simple cells in search for an additive Gaussian target embedded in natural images. Statistically nonstationary and non-Gaussian properties of natural scenes preclude calculation of the best linear template from analytic expressions and require an iterative optimization method such as a virtual evolution via a genetic algorithm. Evolved linear receptive fields built from linear combinations of Gabor functions include substantial inhibitory surround, larger than those found in humans performing target search in white noise. The inhibitory surrounds were robust to changes in the contrast of the signal, generalized to a larger calibrated natural image data set, and tasks in which the signal occluded other objects in the image. We show that channel nonlinearities can have strong effects on the observed linear behavioral receptive field but preserve the inhibitory surrounds. Together, the results suggest that the apparent suboptimality of inhibitory surrounds in human behavioral receptive fields when searching for a target in white noise might reflect a strategy to optimize detection of signals in natural scenes. Finally, we contend that optimized linear detection of spatially compact signals in natural images might be a new possible hypothesis, distinct from decorrelation of visual input and sparse representations (e.g., Graham et al., 2006), to explain the evolution of center-surround organization of receptive fields in early vision.
Predictors of radiolucent foreign body aspiration

Abstract Background Children frequently present for suspected foreign body aspiration, many have mild symptoms and/or negative radiographs raising the question of a radiolucent foreign body aspiration. Method Retrospective review of patients having bronchoscopy for suspected radiolucent foreign body aspiration from 2000 to 2010 collecting demographics, history, hospital presentation, radiographic, and operative details. Pearson's correlation was used between event history, presentation, radiographic details and bronchoscopically identified foreign body with P value Results 138 patients, mean age 2.6years, mean weight 15.6kg, 68% male. Event symptoms: 81% witnessed events, 64% wheezing, 43% coughing, 39% choking, 6% stridor, and 0.7% lethargy. Hospital presentation: 70% persistent symptoms, wheezing 56%, coughing 15%, desaturations 11%, stridor 7%, choking 4%, and lethargy 1%. 92% of patients had a chest x-ray; air trapping found in 38%, and lung collapse in 21%. 2 patients received CT scans; 1 had lung collapse. Bronchoscopy identified foreign bodies in 93% of patients: food 68%, plastic 18%, non-descript 11%, rocks 3%. No correlations between event symptoms, hospital presentation, radiographs and foreign body presence. Conclusion Event history, hospital presentation, and radiographs are insufficient in proving the absence of a radiolucent foreign body. Patients with suspected radiolucent foreign body aspiration should undergo diagnostic bronchoscopy prior to discharge.
On Perturbative PSU(n) Invariants of Rational Homology 3-Spheres

Abstract We construct power series invariants of rational homology 3-spheres from quantum PSU(n) -invariants. The power series can be regarded as perturbative invariants corresponding to the contribution of the trivial connection in the hypothetical Witten’s integral. This generalizes a result of Ohtsuki (the n=2 case) which led him to the definition of finite type invariants of 3-manifolds. The proof utilizes some symmetry properties of quantum invariants (of links) derived from the theory of affine Lie algebras and the theory of the Kontsevich integral.
Binary Space Partitions for Axis-Parallel Segments, Rectangles, and Hyperrectangles

We provide a variety of new upper and lower bounds and simpler proof techniques for the efficient construction of binary space partitions (BSPs) of axis-parallel rectangles of various dimensions. (a) We construct a set of $n$ disjoint axis-parallel segments in the plane such that any binary space auto-partition has size at least $2n-o(n)$, almost matching an upper bound of d’Amore and Franciosa. (b) We establish a similar lower bound of $7n/3-o(n)$ for disjoint rectangles in the plane. (c) We simplify and improve BSP constructions of Paterson and Yao for disjoint segments in $\reals^d$ and disjoint rectangles in $\reals^3$. (d) We derive a worst-case bound of $\Theta(n^{5/3})$ for the size of BSPs of disjoint $2$-rectangles in $4$-space. (e) For disjoint $k$-rectangles in $d$-space, we prove the worst-case bound $\Theta(n^{d/(d-k)})$, for any $k<d/2$; this bound holds for all $k<d$ if the rectangles are allowed to intersect.
From text to structured information: automatic processing of medical reports

This paper describes the analysis and processing programs for a set of natural language texts in a medical area (x-ray reports on patients with breast cancer). The programs convert the information in the text into a tabular form suitable for further automatic information processing (e.g., editing of records, question answering on the data collected, or statistical summaries of the data). To set up a tabular form appropriate for the data, we first perform a manual linguistic analysis on a sample of the texts. From this we obtain the word classes and the form of the table (called an information format) for this type of material. We then apply the series of processing programs to the sentences of the texts. Each sentence is parsed with the Linguistic String Parser English grammar in order to obtain its grammatical structure; certain standard English transformations are then applied to regularize the grammatical form of the sentence; and finally a set of "formatting transformations" map the words of the sentence into the slots of the format or table, in such a way that the sentence is reconstructible (up to paraphrase) from its representation in the table. The results of applying these programs to a corpus are described. This procedure enables us to convert a natural language corpus into a structured data base.
CLASSICAL UNDERPINNINGS OF GRAVITATIONALLY INDUCED QUANTUM INTERFERENCE

We show that the gravitational modification of the phase of a neutron beam [the Colella-Overhauser-Werner (COW) experiment] has a classical origin, being due to the time delay that classical particles experience in traversing a background gravitational field. Similarly, we show that classical light waves also undergo a phase shift in traversing a gravitational field. We show that the COW experiment respects the equivalence principle even in the presence of quantum mechanics. {copyright} {ital 1998} {ital The American Physical Society}
Legislative fractionalization and partisan shifts to the left increase the volatility of public energy R&D expenditures

Abstract This article shows that legislative fractionalization and leftward (but not rightward) partisan shifts increase the volatility of public R&D expenditures in new energy technologies. We develop a highly accurate estimator for public energy R&D expenditures, and examine deviations from the estimated values using data for member states of the International Energy Agency, 1981–2007. Given that unpredictable fluctuation in public spending on new energy technology reduces the positive effect of such spending on innovation, our empirical analyses imply that countries with fractionalized legislatures can improve the performance of their energy technology programs by enacting institutional mechanisms that reduce the volatility of public spending. Similarly, the results indicate that left-wing and right-wing governments can improve the performance of public technology programs through agreements that distribute gains in such a fashion that partisan shifts do not cause spending cuts. Contravening the conventional wisdom, we also find that public energy R&D is unusually stable in the United States.
Objective Functions and Models of Corporate Optimization

I. Economic theory and the goals of the firm, 345. — II. The corporate economy, 356. — III. Problems in the specification of goals, 360. — IV. Some recent approaches to the study of economic intent, structure, and behavior, 368. — V. Power, intent and policy, 374.
Identification of 3D objects from multiple silhouettes using Quadtrees/Octrees

Abstract Octrees have been extensively used for 3D object representation. The authors have previously developed a scheme, that exploits the volume intersection approach, to generate the octree of an object from three orthogonal views. In this paper, the scheme is extended to generate a “generalized octree” of an object from three known non-coplanar views. The block associated with each node in a generalized octree is a parallelepiped, instead of being a cube. To identify an observed object, the generalized octree of the object is projected onto the corresponding principal planes and matched against a number of models, each of which is represented by a set of the quadtrees from three principal views. To speed up the processing, reconstruction of the structure of the object as well as computation of its moment of inertia matrix (comprising all the second-order moments) are performed in a generalized coordinate system specified by the three viewing directions. The coordinate transformation is applied only to the moment of inertia matrix. The principal axes are obtained from the transformed moment of inertia matrix by computing its eigenvectors. A “coarse” matching is performed by matching the quadtrees of the unknown object to those of the models, so as to extract a smaller set of models with strong similarity to the unknown object. The octrees of these models are then matched to that of the object using a “fine” matching process. The results of experiments conducted demonstrate that this approach makes both storage and computation highly efficient.
A Deep Multicolor Survey. VI. Near-Infrared Observations, Selection Effects, and Number Counts*

I present near-infrared J (1.25 ?m), H (1.65 ?m), and K (2.2 ?m) imaging observations of 185 arcmin2 in 21 high galactic latitude fields. These observations reach limiting magnitudes of J ~ 21, H ~ 20, and K ~ 18.5 mag. The detection efficiency, photometric accuracy, and selection biases as a function of integrated object brightness, size, and profile shape are quantified in detail. I evaluate several popular methods for measuring the integrated light of faint galaxies and show that only aperture magnitudes provide an unbiased measure of the integrated light that is independent of apparent magnitude. These J, H, and K counts and near-infrared colors are in best agreement with passive galaxy formation models with at most a small amount of merging (for ?M = 0.3 and ?? = 0.7).
Modeling crater populations on Venus and Titan

Abstract We describe a model for crater populations on planets and satellites with dense atmospheres, like those of Venus and Titan. The model takes into account ablation (or mass shedding), pancaking, and fragmentation. Fragmentation is assumed to occur due to the hydrodynamic instabilities promoted by the impactors’ deceleration in the atmosphere. Fragments that survive to hit the ground make craters or groups thereof. Crater sizes are estimated using standard laws in the gravity regime, modified to take into account impactor disruption. We use Monte Carlo methods to pick parameters from appropriate distributions of impactor mass, zenith angle, and velocity. Good fits to the Venus crater populations (including multiple crater fields) can be found with reasonable values of model parameters. An important aspect of the model is that it reproduces the dearth of small craters on Venus: this is due to a cutoff on crater formation we impose, when the expected crater would be smaller than the (dispersed) object that would make it. Hydrodynamic effects alone (ablation, pancaking, fragmentation) due to the passage of impactors through the atmosphere are insufficient to explain the lack of small craters. In our favored model, the observed number of craters (940) is produced by ∼ 5500 impactors with masses > 10 15 gm , yielding an age of 730 ± 110 Myr (1- σ uncertainty) for the venusian surface. This figure does not take into account any uncertainties in crater scaling and impactor population characteristics, which probably increase the uncertainty to a factor of two in age. We apply the model with the same parameter values to Titan to predict crater populations under differing assumptions of impactor populations that reflect present conditions. We assume that the impactors (comets) are made of 50% porous ice. Predicted crater production rates are ≈ 190 craters ( 10 9 yr ) - 1 . The smallest craters on Titan are predicted to be ≈ 2 km in diameter, and ≈ 5 crater fields ( 10 9 yr ) - 1 are expected. If the impactors are composed of solid ice (density 0.92 gm cm - 3 ), crater production rates increase by ≈ 70 % and the smallest crater is predicted to be ≈ 1.6 km in diameter. We give cratering rates for denser comets and atmospheres 0.1 and 10 times as thick as Titan's current atmosphere. We also explicitly address leading-trailing hemisphere asymmetries that might be seen if Titan's rotation rate were strictly synchronous over astronomical timescales: if that is the case, the ratio of crater production on the leading hemisphere to that on the trailing hemisphere is ≈ 4 : 1 .
Mechanism and kinetics of excited‐state relaxation in internally hydrogen‐bonded molecules: 2‐(2′‐hydroxy‐5′‐methylphenyl)‐benzotriazole in solution

We report the ground state absorption recovery kinetics (at 355 nm) and the fluorescence spectra and kinetics of 2‐(2′‐hydroxy‐5′‐methylphenyl)‐benzotriazole (I) following excitation at 355 nm in several solvents at room temperature. Measured lifetimes range from 14 to 75 ps. Fluorescence lifetimes are shorter than the corresponding ground state recovery times, indicating the intervention of intermediate forms during the excited state relaxation process. The measured fluorescence quantum yield is lower than one predicted by the usual calculated radiative rate for the near UV, strongly absorbing singlet state of this molecule. Decay rates are slower in ethanol than in nonhydrogen bonding solvents indicating that external interference with the intramolecular hydrogen bond in (I) slows the relaxation rate. The room temperature decay rates are not strongly affected by the solvent viscosity. Deuteration of the molecule produces only a slightly more rapid ground state recovery rate than in the protonated specie...
Detailed Numerical Simulations of the Primary Atomization of a Turbulent Liquid Jet in Crossflow

This paper presents numerical simulation results of the primary atomization of a turbulent liquid jet injected into a gaseous crossflow. Simulations are performed using the balanced force refined level set grid method. The phase interface during the initial breakup phase is tracked by a level set method on a separate refined grid. A balanced force finite volume algorithm together with an interface projected curvature evaluation is used to ensure the stable and accurate treatment of surface tension forces even on small scales. Broken off, small scale nearly spherical drops are transferred into a Lagrangian point particle description allowing for full two-way coupling and continued secondary atomization. The numerical method is applied to the simulation of the primary atomization region of a turbulent liquid jet (q=6.6, We=330, Re=14,000) injected into a gaseous crossflow (Re=570,000), analyzed experimentally by Brown and McDonell (2006, “Near Field Behavior of a Liquid Jet in a Crossflow,” ILASS Americas, 19th Annual Conference on Liquid Atomization and Spray Systems). The simulations take the actual geometry of the injector into account. Grid converged simulation results of the jet penetration agree well with experimentally obtained correlations. Both column/bag breakup and shear/ligament breakup modes can be observed on the liquid jet. A grid refinement study shows that on the finest employed grids (flow solver 64 points per injector diameter, level set solver 128 points per injector diameter), grid converged drop sizes are achieved for drops as small as one-hundredth the size of the injector diameter.
Heating and Ionization of the Intergalactic Medium by an Early X-Ray Background

Observational studies indicate that the intergalactic medium (IGM) is highly ionized up to redshifts just over 6. A number of models have been developed to describe the process of reionization and the effects of the ionizing photons from the first luminous objects. In this paper we study the impact of an X-ray background, such as high-energy photons from early quasars, on the temperature and ionization of the IGM prior to reionization, before the fully ionized bubbles associated with individual sources have overlapped. X-rays have large mean free paths relative to EUV photons, and their photoelectrons can have significant effects on the thermal and ionization balance. We find that hydrogen ionization is dominated by the X-ray photoionization of neutral helium and the resulting secondary electrons. Thus, the IGM may have been warm and weakly ionized prior to full reionization. We examine several related consequences, including the filtering of the baryonic Jeans mass scale, signatures in the cosmic microwave background, and the H--catalyzed production of molecular hydrogen.
Conservation laws for relativistic guiding-center plasma

Abstract A covariant relativistic formulation is used for the self-consistent dynamics of a guiding-center plasma in an electromagnetic field. The reciprocal interactions appear as a magnetization in Maxwell's equations and as field gradient forces in the guiding-center dynamical equation. The ten local conservation laws corresponding to translational and rotational invariance of the Minkowski space are expressed in terms of a symmetric energy-momentum tensor.
The ontogeny of human hearing

The development of human hearing from the 26th week of fetal life to the third year post natal life is reviewed. The human fetus can perceive, react, and store auditory information from the 26th week of fetal life. This ability appears to play a role in the development of language. Infants by the 2nd to 3rd month of postpartum life have categorical perception for most phonemes whether or not these phonemes are native to their own language. The infant has a difference limen similar to that of the adult. The infant threshold is higher; the single-to-noise ratio is greater in infants than adults; and the infant's temporal processing is slower than that of the adult.
Solution to the Incorrect Benchmark Shell-Buckling Problem

A benchmark, geometrically nonlinear, shell-buckling problem is reviewed and the correct solution is identified and discussed vis-a-vis the incorrect solution from the open literature. The problem is that of a hinged, thin, isotropic cylindrical shell section, point-loaded transversely at the center, undergoing large deformations (5 x thickness). This benchmark problem and solution were introduced in 1972 and have been reproduced in at least 30 journal articles and books in the more than three decades since that time. The benchmark problem is of interest because it demonstrates many features possible in shell buckling, including a load-limit point (snap-through buckling) and a deflection-limit point (snap-down, or snap-back). The benchmark problem is typically used to demonstrate the capability of commercial/private finite element codes to traverse such complicated nonlinear load paths. The existing incorrect benchmark solution involves the nonlinear growth of only symmetric deformation modes. The correct solution to this benchmark problem involves bifurcation from the nonlinear load path into a simple asymmetric deformation mode. Experimental data do not exist for verification of the calculated benchmark response, and so a similar problem using a laminated composite shell is suggested as an alternative benchmark problem for shell stability analysis.
Portfolio Performance Evaluation Using Value at Risk

Developed here is a value at risk-based measure of portfolio performance called the reward-to-VaR ratio. It is demonstrated that, under normality, the reward-to-VaR ratio gives the same ranking for portfolio performance as the frequently used Sharpe ratio. Under non-normality, the reward-to-VaR ratio at one confidence level may give a ranking for portfolio performance different from the ranking obtained at a different confidence level. This indicates that the risk-taking incentives of a portfolio manager in a VaR-based risk management system can be substantially different from the incentives in a Sharpe ratio-based system.
Rac GTPases play multiple roles in erythropoiesis

The four members of the Rac family of GTPases –Rac1, Rac2, Rac3 and RhoG – are members of the Rho superfamily that regulates the organization, dynamics, and function of the actin cytoskeleton. Rac GTPases play significant roles in many cellular processes including migration, cytokinesis,
Use of amine electride chemistry to prepare molybdenum disulfide intercalation compounds

Electride solutions, formed by dissolution of Na(m) in ethylenediamine (en), are used to generate MoS2 intercalation compounds. Two new intercalation compounds were obtained, labeled α and β phases, containing both Na and en as intercalate and cointercalate respectively. The intercalation reaction proceeds via formation of a kinetic product, the β phase, and subsequent generation of a stable thermodynamic product, the α phase. The β and α phases have interlayer distances, dIC, of 1.19 and 0.97 nm, respectively, which are ascribed to a perpendicular or parallel orientation of en within the intercalate galleries. Product compositions, morphologies and spectrochemical features are obtained from thermogravimetry, SEM and Raman measurement. Electrochemical reduction of MoS2 in an en-based electrolyte is investigated, but does not show the same intercalation reactions. The chemistry observed is compared with that previously reported for this and other MS2 hosts, and with graphite intercalation.
Processing a trillion cells per mouse click

Column-oriented database systems have been a real game changer for the industry in recent years. Highly tuned and performant systems have evolved that provide users with the possibility of answering ad hoc queries over large datasets in an interactive manner.In this paper we present the column-oriented datastore developed as one of the central components of PowerDrill. It combines the advantages of columnar data layout with other known techniques (such as using composite range partitions) and extensive algorithmic engineering on key data structures. The main goal of the latter being to reduce the main memory footprint and to increase the efficiency in processing typical user queries. In this combination we achieve large speed-ups. These enable a highly interactive Web UI where it is common that a single mouse click leads to processing a trillion values in the underlying dataset.
Dual fermion method for disordered electronic systems

While the coherent potential approximation (CPA) is the prevalent method for the study of disordered electronic systems, it fails to capture nonlocal correlations and Anderson localization. To incorporate such effects, we extend the dual fermion approach to disordered systems using the replica method. The developed method utilizes the exact mapping to the dual fermion variables, and includes intersite scattering via diagrammatic perturbation theory in the dual variables. The CPA is recovered as a zeroth-order approximation. Results for single- and two-particle quantities show good agreement with a cluster extension of the CPA; moreover, weak localization is captured. As a natural extension of the CPA, our method presents an alternative to existing nonlocal cluster theories for disordered systems, and has potential applications in the study of disordered systems with electronic interactions.
THE CRAB NEBULA'S COMPOSITION AND PRECURSOR STAR MASS

We present new photoionization calculations for investigating gaseous regions that represent potentially expected stages of nuclear processing in the Crab Nebula supernova remnant. From comparison of the theoretical models with recent, extensive emission-line measurements, most of the emitting gas appears to be nitrogen-poor and carbon-rich. These results suggest that the precursor star had an initial mass 9.5 M ?.
Correlation of the glass transition and the pressure dependence of viscosity in liquids

The determination of the glass‐transition pressure by the ruby R1 line‐broadening method is quantitatively confirmed to within 10% by an independent method. The procedure utilizes a model which describes the pressure dependence of the viscosity and contains the glass‐transition pressure as a parameter. The two methods are compared for three liquids, n‐butyl chloride, 4 : 1 methanol‐ethanol, and isopropyl alcohol. Data from earlier works are used for 4 : 1 methanol‐ethanol and isopropyl alcohol. The viscosity of n‐butyl chloride at room temperature is measured as a function of pressure to 36 kbars in a diamond‐anvil falling‐sphere viscometer, and the glass‐transition pressure is determined by a separate measurement using the ruby R1 line‐broadening method.
Skin Bleaching, Self-Hate, and Black Identity in Jamaica:

The Afrocentric view concerning Jamaicans who bleach their skins is that they suffer from self-hate, a result of the lingering psychological scars of slavery. The self-hatred thesis is tested by comparing the self-esteem scores of a small convenience sample of skin bleachers with the scores of a control group. The two groups have almost the same average scores above the median, which indicates that skin bleaching did not occur because of low self-esteem. The preliminary results suggest that there are varied reasons for skin bleaching and there is a range of Black identities as each person constructs his or her identity in a multicultural society.
Salinity trends on the Siberian shelves

[1] We present an analysis of observed long-term (∼100 year) salinity trends on the freshwater-dominated Siberian continental shelves. A multiple regression was performed in the White Sea (WS), the Kara Sea (KS), the Laptev Sea (LS), and the East Siberian Sea (ESS). Since 1930, the WS has gained freshwater while the ESS has lost it, consistent with river discharge trends over this period. Over the past 20 years, increases in both river discharge and direct precipitation can explain observed salinity decreases in the WS, but not in the KS. Salinity trends in the LS and ESS indicate that ocean circulation plays a dominate role in these areas, where in recent years freshwater has been diverted eastward along the coast, rather than northward toward the deep ocean.
Dualities from higher-spin supergravity

We study the vacuum structure of spin-3 higher-spin supergravity in AdS3 spacetime. The theory can be written as a Chern-Simons theory based on the Lie superalgebra sl(3|2). We find three distinct AdS3 vacua, AdS(1), AdS(2) and AdS(p), each corresponding to one embedding of the osp(1|2) subalgebra into the sl(3|2) algebra. We explicitly construct the RG flows from AdS(1) to AdS(p) and from AdS(2) to AdS(p), which identifies AdS(p) as an IR vacuum and AdS(1), AdS(2) as two different UV vacua. Thus a duality is found between the two UV theories in the sense that the two theories, each with a chemical potential turned on, flow to the same IR theory. Moreover, we identify a similar structure in the Hamiltonian reductions of the 2d Wess-Zumino-Witten (WZW) model with sl(3|2)-valued currents by matching the chiral symmetries there with the asymptotic symmetries of the three different embeddings. Our computation gives an RG interpretation of (certain types of) the Hamiltonian reductions. In addition, it gives a hint of a duality between the 3d higher-spin supergravity and some conformally extended super-Toda theory as suggested by Mansfield and Spence for the bosonic case.
Are Clusters Standard Candles? Galaxy Cluster Scaling Relations with the Sunyaev-Zeldovich Effect

An extensive sample of galaxy clusters will be available in the coming years, detected through their Sunyaev-Zeldovich effect (SZE). We use a semianalytic model to study the scientific yield of combining SZE data with X-ray and optical follow-up observations. If clusters at a given redshift z0 can be identified with virialized, spherical halos, they populate a well-defined "fundamental plane" (FP) in the parameter space of the three observables virial temperature (T), total Sunyaev-Zeldovich flux decrement (ΔSν), and angular size (θ). The location and orientation of the FP, as well as its redshift evolution, are sensitive to both the internal evolution of clusters and to the underlying cosmological parameters. We show that if clusters are not standard candles (e.g., because of feedback or energy injection), then this can be inferred from the FP. Likewise, we study the dependence of the FP on the cosmological parameters h, σ8, and Ω0, and quantify future constraints on these parameters. We also show that in the absence of any nongravitational effects, the scatter in the (ΔSν,T)-plane is significantly smaller than in either the (θ,T) or the (θ,ΔSν) planes. As a result, the ΔSν-T relation can be an exceptionally sensitive probe of both cluster physics and cosmological parameters. A comparison of the amount of scatter in these three scaling relations will test the origin (cosmological vs. stochastic) of the scatter.
Buckling and Failure of Sandwich Plates with Graphite-Epoxy Faces and Various Cores

A study of the compressive failure of sandwich plates was conducted. Twenty-one panels (250 X 250 mm) were manufactured with [ + 457 - 45/0 ]s graphite-epoxy face sheets and three types of cores- Nomex honeycomb, Rohacell foam, and aluminum honeycomb-in three different thicknesses - 3.2, 6.4, and 9.6 mm. These panels were tested under uniaxial compression with clamped loaded edges and simply supported sides, and overall buckling was the only type of instability that was observed here. The effects of these different cores were investigated, and three types of failure modes were observed - core failure, disbond, and face fracture. Initial out-of-plane imperfections were found to have an important effect on the final failure load for thick panels but only a small influence for thin panels. Using the stresses predicted by a nonlinear analysis and appropriate failure criteria, namely maximum transverse shear stress for the core or bond failure and stress interaction for the face fracture, failure load predictions that are in good agreement with the experimental data can be made.
EVOLUTION OF X-RAY SPECTRA AND LIGHT CURVES OF V1494 AQUILAE

We present six Chandra X-ray spectra and light curves obtained for the nova V1494 Aql (1999 No. 2) in outburst. The first three observations were taken with the Advanced CCD Imaging Spectrometer (ACIS-I) on days 134, 187, and 248 after outburst. The count rates were 1.00, 0.69, and 0.53 counts s{sup -1}, respectively. We found no significant periodicity in the ACIS light curves. The X-ray spectra show continuum emission and lines originating from N and O. We found acceptable spectral fits using isothermal APEC models with significantly increased elemental abundances of O and N for all observations. On day 248 after outburst a bright soft component appeared in addition to the fading emission lines. The Chandra observations on days 300, 304, and 727 were carried out with the High Resolution Camera/Low Energy Transmission Grating Spectrometer (LETGS). The spectra consist of continuum emission plus strong emission lines of O and N, implying a high abundance of these elements. On day 300, a flare occurred and periodic oscillations were detected in the light curves taken on days 300 and 304. This flare must have originated deep in the outflowing material since it was variable on short timescales. The spectra extracted immediately beforemore » and after the flare are remarkably similar, implying that the flare was an extremely isolated event. Our attempts to fit blackbody, cloudy, or APEC models to the LETGS spectra failed, owing to the difficulty in disentangling continuum and emission-line components. The spectrum extracted during the flare shows a significant increase in the strengths of many of the lines and the appearance of several previously undetected lines. In addition, some of the lines seen before and after the flare are not present during the flare. On day 727 only the count rate from the zeroth order could be derived, and the source was too faint for the extraction of a light curve or spectrum.« less
On the Computation of Clebsch-Gordan Coefficients and the Dilation Effect

We investigate the problem of computing tensor product multiplicities for complex semisimple Lie algebras. Even though computing these numbers is #P-hard in general, we show that when the rank of the Lie algebra is assumed fixed, then there is a polynomial-time algorithm, based on counting lattice points in polytopes. In fact, for Lie algebras of type A, there is an algorithm, based on the ellipsoid algorithm, to decide when the coefficients are nonzero in polynomial time for arbitrary rank. Our experiments show that the lattice point algorithm is superior in practice to the standard techniques for computing multiplicities when the weights have large entries but small rank. Using an implementation of this algorithm, we provide experimental evidence for two conjectured generalizations of the saturation property of Littlewood–Richardson coefficients. One of these conjectures seems to be valid for types B, C ,a ndD.
Rational design of new binding specificity by simultaneous mutagenesis of calmodulin and a target peptide.

Calcium-saturated calmodulin (CaM) binds and influences the activity of a varied collection of target proteins in most cells. This promiscuity underlies the role of CaM as a shared participant in calcium-dependent signal transduction pathways but imposes a handicap on popular CaM-based calcium biosensors, which display an undesired tendency to cross-react with cellular proteins. Designed CaM/ target pairs that retain high affinity for one another but lack affinity for wild-type CaM and its natural interaction partners would therefore be useful as sensor components and possibly also as elements of "synthetic" cellular-signaling networks. Here, we have adopted a rational approach to creating suitably modified CaM/target complexes by using computational design methods to guide parallel site-directed mutagenesis of both binding partners. A hierarchical design procedure was applied to suggest a small number of complementary mutations on CaM and on a peptide ligand derived from skeletal-muscle light- chain kinase (M13). Experimental analysis showed that the procedure was successful in identifying CaM and M13 mutants with novel specificity for one another. Importantly, the designed complexes retained an affinity comparable to the wild-type CaM/M13 complex. These results represent a step toward the creation of CaM and M13 derivatives with specificity fully orthogonal to the wild-type proteins and show that qualitatively accurate predictions may be obtained from computational methods applied simultaneously to two proteins involved in multiple-linked binding equilibria.
Fundamental constants and tests of theory in Rydberg states of one-electron ions

The nature of the theory of circular Rydberg states of hydrogen-like ions allows highly accurate predictions to be made for energy levels. In particular, uncertainties arising from the problematic nuclear size correction which beset low angular-momentum states are negligibly small for the high angular-momentum states. The largest remaining source of uncertainty can be addressed with the help of quantum electrodynamics calculations, including a new nonperturbative result reported here. More stringent tests of theory and an improved determination of the Rydberg constant may be possible if predictions can be compared with precision frequency measurements in this regime. The diversity of information can be increased by utilizing a variety of combinations of ions and Ryberg states to determine fundamental constants and test theory.
Comparison of an analytical approximation for particle motion in a current sheet with precise numerical calculations

Approximate analytic solutions exist for particle motion in a one-dimensional current sheet with a constant normal magnetic field component. These solutions are tested against precise numerical calculations, and a range of validity of the analytic solutions is inferred. For example, in the geomagnetic tail neutral sheet, for a dawn-dusk electric field of 0.1-1 mV/m, lobe field of 10-40 nT, and sheet thickness of 1000 km, the analytic solutions serve as a good predictor of particle motion when the normal magnetic field component is less than 3 or 4 nT. By using the analytic solutions, initial distribution functions are mapped into final (accelerated) distributions, and the analytic mappings are compared with numerical mappings.
Mass, metal, and energy feedback in cosmological simulations

Using GADGET-2 cosmological hydrodynamic simulations including an observationally constrained model for galactic outflows, we investigate how feedback from star formation distributes mass, metals, and energy on cosmic scales from z = 6 → 0. We include instantaneous enrichment from Type II supernovae (SNe), as well as delayed enrichment from Type Ia SNe and stellar [asymptotic giant branch (AGB)] mass loss, and we individually track carbon, oxygen, silicon and iron using the latest yields. Following on the success of the momentum-driven wind scalings, we improve our implementation by using an on-the-fly galaxy finder to derive wind properties based on host galaxy masses. By tracking wind particles in a suite of simulations, we find: (1) wind material re-accretes on to a galaxy (usually the same one it left) on a recycling time-scale that varies inversely with galaxy mass (e.g. <1 Gyr for L ∗ galaxies at
Characterization of the drag force in an air-moderated granular bed

We measure the torque acting on a rod rotated perpendicular to its axis in a granular bed, through which an upflow of gas is utilized to tune the hydrostatic loading between grains. At low rotation rates the torque is independent of speed, but scales quadratically with rod-length and linearly with depth; the proportionality approaches zero linearly as the upflow of gas is increased towards a critical value above which the grains are fluidized. At high rotation rates the torque exhibits quadratic rate-dependence and scales as the rod's length to the 4th power. The torque has no dependence on either depth or airflow at these higher rates. A model used to describe the stopping force experienced by a projectile impacting a granular bed can be shown to predict these behaviors for our system's geometry, indicating that the same mechanics dictate both steady-state and transient drag forces in granular systems, regardless of geometry or material properties of the grains.
Diagnostic flexible bronchoscopy in human immunodeficiency virus (HIV)-positive children☆

Abstract Twelve children with laboratory evidence of human immunodeficiency virus (HIV) infection underwent diagnostic flexible bronchoscopy with washings or bronchoalveolar lavage at Bellevue Hospital Center from October 1987 to April 1989. The patients included 7 boys and 5 girls ranging from age 3.5 months to 10 years 5 months. Indications for bronchoscopy included respiratory distress with or without focal changes on chest radiograph in 11 patients, and persistent but asymptomatic right middle lobe collapse in one child. The etiology of pneumonia was diagnosed in 7 children and included Pneumocystis carinii, (PCP) (17%), Streptococcus viridans (17%), mechanical obstruction (17%) and cytomegalovirus (CMV) (8%). Bronchoscopy was non-diagnostic in 5 cases. Techniques for maximal yield of information using flexible bronchoscopy in HIV-positive children are discussed.
STRATEGIES FOR SPECTRAL PROFILE INVERSION USING ARTIFICIAL NEURAL NETWORKS

This paper explores three different strategies for the inversion of spectral lines (and their Stokes profiles) using artificial neural networks. It is shown that a straightforward approach in which the network is trained with synthetic spectra from a simplified model leads to considerable errors in the inversion of real observations. This problem can be overcome in at least two different ways that are studied here in detail. The first method makes use of an additional preprocessing autoassociative neural network to project the observed profile into the theoretical model subspace. The second method considers a suitable regularization of the neural network used for the inversion. These new techniques are shown to be robust and reliable when applied to the inversion of both synthetic and observed data.
Statistical modeling of behavioral dynamics during propofol-induced loss of consciousness.

Abstract Background Accurate quantitative analysis of the changes in responses to external stimuli is crucial for characterizing the timing of loss and recovery of consciousness induced by anesthetic drugs. We studied induction and emergence from unconsciousness achieved by administering a computer-controlled infusion of propofol to ten human volunteers. We evaluated loss and recovery of consciousness by having subjects execute every 4 s two interleaved computer delivered behavioral tasks: responding to verbal stimuli (neutral words or the subject's name), or less salient stimuli of auditory clicks. New method We analyzed the data using state-space methods. For each stimulus type the observation model is a two-stage binomial model and the state model is two dimensional random walk in which one cognitive state governs the probability of responding and the second governs the probability of correctly responding given a response. We fit the model to the experimental data using Bayesian Monte Carlo methods. Results During induction subjects lost responsiveness to less salient clicks before losing responsiveness to the more salient verbal stimuli. During emergence subjects regained responsiveness to the more salient verbal stimuli before regaining responsiveness to the less salient clicks. Comparison with existing method(s) The current state-space model is an extension of previous model used to analyze learning and behavioral performance. In this study, the probability of responding on each trial is obtained separately from the probability of behavioral performance. Conclusions Our analysis provides a principled quantitative approach for defining loss and recovery of consciousness in experimental studies of general anesthesia.
Non-Representational Jurisprudence: A Centennial Reading of “The Path of the Law”

This paper analyzes particular passages in Holmes's famous lecture, and notes important inconsistencies and failings in his approach. After arguing strongly that moral considerations should not enter into legal judgments, he criticizes legal judgments in the light of moral considerations. After defining law as a prediction of what the courts will do, he seems to criticize courts for getting the law wrong in their decisions. His advice to learn the legal profession by studying law from the standpoint of a bad man leaves out of account the numerous potential clients who wish to be law abiding citizens and to seal with their associates in accordance with law. The paper recognizes the importance of Holmes's contribution, but suggests regarding it as a set of fragmented views from different standpoints rather than a coherent view of the whole legal system.
Mutation of a Putative Mitochondrial Iron Transporter Gene ( ABC7 ) in X-Linked Sideroblastic Anemia and Ataxia (XLSA/A)

Mutation of a Putative Mitochondrial Iron Transporter Gene ( ABC7 ) in X-Linked Sideroblastic Anemia and Ataxia (XLSA/A)
Channel reduction and applications to image processing

Oftentimes when one is dealing with digital color images it is desired that some sort of image processing be performed on the spatial information. Current methods require that one process each of the channels (also called planes or colors) of an image separately, which increases the number of computations significantly. A novel, to our knowledge, approach to reducing the number of channels in a color image is presented. The channel-reduction process is intended to facilitate such color image-processing situations essentially by the separation of the spectral information from the spatial information, as in a paint-by-numbers picture. In this case the image processing need be applied only to a single channel of data and the color added afterward. With a compression ratio of slightly less than 3:1 the method is not intended to compete with existing compression methods but rather to permit the processing of images in a compressed state.
Accurate time-domain gravitational waveforms for extreme-mass-ratio binaries

The accuracy of time-domain solutions of the inhomogeneous Teukolsky equation is improved significantly. Comparing energy fluxes in gravitational waves with highly accurate frequency-domain results for circular equatorial orbits in Schwarzschild and Kerr, we find agreement to within 1% or better, which may be even further improved. We apply our method to orbits for which frequency-domain calculations have a relative disadvantage, specifically high-eccentricity (elliptical and parabolic) "zoom-whirl" orbits, and find the energy fluxes, waveforms, and characteristic strain in gravitational waves.
The Advanced Solid Rocket Motor

The paper describes the Advanced Solid Rocket Motor (ASRM) that is being developed to replace, in 1997, the Redesigned Solid Rocket Motor which currently boosts the Space Shuttle. The ASRM will contain features to improve motor safety (fewer potential leak paths, improved seal materials, stronger case material, and fewer nozzle and case joints), an improved ignition system using through-bulkhead initiators, and highly reproducible manufacturing and inspection techniques with a large number of automated procedures. The ASRM will be able to deliver 12,000 lbs greater payloads to any given orbit of the Shuttle. There are also environmental improvements, realized by waste propellant recovery.
Thermodynamics of the Superfluid Dilute Bose Gas with Disorder

We generalize the Beliaev-Popov diagrammatic technique for the problem of interacting dilute Bose gas with weak disorder. Averaging over disorder is implemented by the replica method. The low-energy asymptotic form of the Green function confirms that the low-energy excitations of the superfluid dirty-boson system are sound waves with velocity renormalized by the disorder and additional dissipation due to the impurity scattering. We find the thermodynamic potential and the superfluid density at any temperature below the superfluid transition temperature (but outside the Ginzburg region) and derive the phase diagram in temperature vs disorder plane.