cssi/SciSciGPT-SciSciNet huggingface dataset:
Structure determination of La3CuGeS7 and La3CuGeSe7

Abstract We have synthesized La 3 CuGeS 7 and La 3 CuGeSe 7 and characterized their structures from single crystal X-ray diffraction data. From lattice constant data alone, Guittard et al. [C.R. Acad. Sci. Paris 267 (1968) 767; Bull. Soc. Chim. Fr. 7 (1970) 2467] had assumed that both of these phases were members of a large family of hexagonal compounds with the general formula Ln 6 MS 6 (TX 4 ) 2 or Ln 6 M 2 ′S 6 (TX 4 ) 2 , where Ln=lanthanide element, M=divalent element (Mg, Ni, Mn), M′=monovalent element (Cu, Ag), T=(Ge, Si, Al or Fe), and X=(S, Se); our data confirm this assumption. La 3 CuGeS 7 and La 3 CuGeSe 7 both contain isolated [Ge(S,Se)] 4− tetrahedra, trigonal planar Cu(S,Se) 3 units, and La counter-cations. Consistent with its assignment to a non-centrosymmetric space group ( P 6 3 ), La 3 CuGeSe 7 shows a weak second harmonic generation response when irradiated with 1064-nm laser light.
The use of tetramethylguanidinium azide in non-halogenated solvents avoids potential explosion hazards

Tetramethylguanidinium azide was used in the quantitative conversion of glycosyl halides 1 – 5 to the corresponding glycosyl azides 10 – 14. The stereoselective reactions occurred with complete inversion at the anomeric centers. The titled reagent was also employed in the selective synthesis of pseudoglycosyl azide 16 and two steroidal azides 17 and 18. All reactions were carried out in non-halogenated solvents to avoid potential explosion hazards.
Synthesis of glycosyl-1-phosphates via dehydrative glycosylation

Direct synthetic access to glycosyl-1-phosphates is accomplished with the dehydrative coupling of carbohydrate hemiacetals and dialkyl phosphates, employing dibenzothiophene-5-oxide and triflic anh...
Prostaglandin E2 gel for cervical ripening and induction of labor: A critical analysis

This report summarizes the cumulative experience of 3313 pregnancies represented in 59 prospective clinical trials in which intracervical or intravaginal prostaglandin E 2 gel was used for cervical ripening before induction of labor. Results indicate that local prostaglandin E 2 is superior to placebo or no therapy in enhancing cervical effacement and dilation, reducing initial induction failures, shortening the induction-delivery interval, reducing oxytocin use, and lowering the rate of cesarean section because of failure to progress. Certain advantages also exist for labor induction in the presence of a favorable cervical state. Uterine hyperstimulation or pathologic fetal heart rate patterns before oxytocin administration occur in 2 gel administered before induction of labor is of major therapeutic benefit and should become commercially available for more than investigational use.
Lifetime of metastable states in resonant tunneling structures

We investigate the transport of electrons through a double-barrier resonant-tunneling structure in the regime where the current-voltage characteristics exhibit bistability. In this regime one of the states is metastable, and the system eventually switches from it to the stable state. We show that the mean switching time $\ensuremath{\tau}$ grows exponentially as the voltage V across the device is tuned from the boundary value ${V}_{\mathrm{th}}$ into the bistable region. In samples of small area we find $\mathrm{ln}\ensuremath{\tau}\ensuremath{\propto}|V\ensuremath{-}{V}_{\mathrm{th}}{|}^{3/2},$ while in larger samples $\mathrm{ln}\ensuremath{\tau}\ensuremath{\propto}|V\ensuremath{-}{V}_{\mathrm{th}}|.$
Degenerate Conformally Invariant Fully Nonlinear Elliptic Equations

We establish Liouville theorems for \(C_{loc}^{1,1}\) , entire solutions and locally Lipschitz entire weak solutions to general degenerate conformally invariant fully nonlinear elliptic equations of second order. For applications to local gradient estimates of solutions of general conformally invariant fully nonlinear elliptic equations of second order, see [20].
Oblique electroweak corrections from heavy scalar fields

The contributions of heavy scalar fields to the oblique electroweak correction parametersS andT are discussed with an emphasis of the decoupling properties of these contributions. It turns out that in the decoupling limit, we also get the custodial symmetry.
Non-Gaussianities in Multi-field Inflation

We compute the amplitude of the non-Gaussianities in inflationary models with multiple, uncoupled scalar fields. This calculation thus applies to all models of assisted inflation, including N-flation, where inflation is driven by multiple axion fields arising from shift symmetries in a flux stabilized string vacuum. The non-Gaussianities are associated with nonlinear evolution of the field (and density) perturbations, characterized by the parameter fNL. We derive a general expression for the nonlinear parameter, incorporating the evolution of perturbations after horizon-crossing. This is valid for arbitrary separable potentials during slow roll. To develop an intuitive understanding of this system and to demonstrate the applicability of the formalism we examine several cases with quadratic potentials: two-field models with a wide range of mass ratios, and a general -field model with a narrow mass spectrum. We uncover that fNL is suppressed as the number of e-foldings grows, and that this suppression is increased in models with a broad spectrum of masses. On the other hand, we find no enhancement to fNL that increases with the number of fields. We thus conclude that the production of a large non-Gaussian signal in multi-field models of inflation is very unlikely as long as fields are slowly rolling and potentials are of simple, quadratic form. Finally, we compute an expression for the scalar spectral index that incorporates the nonlinear corrections to the fields' evolution.
SEMI-SUPERVISED SEQUENCE CLASSIFICATION WITH HMMs

Using unlabeled data to help supervised learning has become an increasingly attractive methodology and proven to be effective in many applications. This paper applies semi-supervised classification algorithms, based on hidden Markov models, to classify sequences. For model-based classification, semi-supervised learning amounts to using both labeled and unlabeled data to train model parameters. We examine three different strategies of using labeled and unlabeled data in the model training process. These strategies differ in how and when labeled and unlabeled data contribute to the model training process. We also compare regular semi-supervised learning, where there are separate unlabeled training data and unlabeled test data, with transductive learning where we do not differentiate between unlabeled training data and unlabeled test data. Our experimental results on synthetic and real EEG time-series show that substantially improved classification accuracy can be achieved by these semi-supervised learning strategies. The effect of model complexity on semi-supervised learning is also studied in our experiments.
Volumetric Segmentation of Medical Images by Three-Dimensional Bubbles

The segmentation of structure from images is an inherently difficult problem in computer vision and a bottleneck to its widespread application, e.g., in medical imaging. This paper presents an approach for integrating local evidence such as regional homogeneity and edge response to form global structure for figure?ground segmentation. This approach is motivated by a shock-based morphogenetic language, where the growth of four types of shocks results in a complete description of shape. Specifically, objects are randomly hypothesized in the form of fourth-order shocks (seeds) which then grow, merge, split, shrink, and, in general, deform under physically motivated “forces,” but slow down and come to a halt near differential structures. Two major issues arise in the segmentation of 3D images using this approach. First, it is shown that the segmentation of 3D images by 3D bubbles is superior to a slice-by-slice segmentation by 2D bubbles or by “212D bubbles” which are inherently 2D but use 3D information for their deformation. Specifically, the advantages lie in an intrinsic treatment of the underlying geometry and accuracy of reconstruction. Second, gaps and weak edges, which frequently present a significant problem for 2D and 3D segmentation, are regularized by curvature-dependent curve and surface deformations which constitute diffusion processes. The 3D bubbles evolving in the 3D reaction?diffusion space are a powerful tool in the segmentation of medical and other images, as illustrated for several realistic examples.
Dew frequency, duration, amount, and distribution in corn and soybean during SMEX05

Dew affects the brightness temperature of vegetation and backscatter from vegetation at microwave wavelengths. Must this effect be taken into account in order to avoid corrupting remotely sensed observations of important ecosystem variables such as soil moisture? As a first step towards answering this question, we report the frequency and duration of dew events, thetotal amount of dewin the canopy, and thedistribution ofdew within the canopy for two different types of crop canopy, corn and soybean, during SMEX05, a 21-day field experiment conducted during June and July, 2005, in Iowa, USA. We observed dew to be present more than 50% of the time in both corn and soybean at common satellite overpass times of 1:30 and 6:00 CST. Dew was most likely to be present between 12:00 and 6:30 CST, and as late as 9:00 CST. Two different methods to scale the liquid water measured on single leaves to the entire vegetation canopy produced similar results, and we observed dew amounts that were comparable, and in some cases higher, than those that have been shown to affect the microwave brightness temperature and backscatter. The distribution of dew within the canopy among the top and bottom of a leaf and (for corn) the leaf collar may influence its effect on remotely sensed measurements. We found that this distribution is different for light, moderate, and heavy dew events. A modeling approach will be necessary to estimate dew at larger spatial scales associated with satellite remote sensing. The Atmosphere-Land Exchange (ALEX) model, a land surface process model that accounts for both dewfall and distillation, produced estimates of dew amount and duration that were in agreement with manual observations and observations made with leaf wetness sensors.
Atomic structure of anthrax protective antigen pore elucidates toxin translocation

Anthrax toxin, comprising protective antigen, lethal factor, and oedema factor, is the major virulence factor of Bacillus anthracis, an agent that causes high mortality in humans and animals. Protective antigen forms oligomeric prepores that undergo conversion to membrane-spanning pores by endosomal acidification, and these pores translocate the enzymes lethal factor and oedema factor into the cytosol of target cells. Protective antigen is not only a vaccine component and therapeutic target for anthrax infections but also an excellent model system for understanding the mechanism of protein translocation. On the basis of biochemical and electrophysiological results, researchers have proposed that a phi (Φ)-clamp composed of phenylalanine (Phe)427 residues of protective antigen catalyses protein translocation via a charge-state-dependent Brownian ratchet. Although atomic structures of protective antigen prepores are available, how protective antigen senses low pH, converts to active pore, and translocates lethal factor and oedema factor are not well defined without an atomic model of its pore. Here, by cryo-electron microscopy with direct electron counting, we determine the protective antigen pore structure at 2.9-A resolution. The structure reveals the long-sought-after catalytic Φ-clamp and the membrane-spanning translocation channel, and supports the Brownian ratchet model for protein translocation. Comparisons of four structures reveal conformational changes in prepore to pore conversion that support a multi-step mechanism by which low pH is sensed and the membrane-spanning channel is formed.
The annual cycle of water vapor on Mars as observed by the Thermal Emission Spectrometer

Spectra taken by the Mars Global Surveyor Thermal Emission Spectrometer (TES) have been used to monitor the latitude, longitude, and seasonal dependence of water vapor for over one full Martian year (March 1999-March 2001). A maximum in water vapor abundance is observed at high latitudes during mid-summer in both hemispheres, reaching a maximum value of approximately 100 pr-micrometer in the north and approximately 50 pr-micrometer in the south. Low water vapor abundance (<5 pr-micrometer) is observed at middle and high latitudes in the fall and winter of both hemispheres. There are large differences in the hemispheric (north versus south) and seasonal (perihelion versus aphelion) behavior of water vapor. The latitudinal and seasonal dependence of the decay of the northern summer water vapor maximum implies cross-equatorial transport of water to the southern hemisphere, while there is little or no corresponding transport during the decay of the southern hemisphere summer maximum. The latitude-longitude dependence of annually-averaged water vapor (corrected for topography) has a significant positive correlation with albedo and significant negative correlations with thermal inertia and surface pressure. Comparison of TES results with those retrieved from the Viking Orbiter Mars Atmospheric Water Detectors (MAWD) experiments shows some similar features, but also many significant differences. The southern hemisphere maximum observed by TES was not observed by MAWD and the large latitudinal gradient in annually-averaged water vapor observed by MAWD does not appear in the TES results.
Coordination compounds of aluminum as precursors to aluminum nitride

Abstract Two different systems have been examined as potential sources of aluminum nitride, an important electronic and structural ceramic material. Cyclic organoaluminum amides obtained as intermediates in the thermolysis of trialkylaluminum : ammonia Lewis acid-base complexes have been used to obtain AlN powder and as precursors for the chemical vapor deposition of AlN films. The structures of two of these intermediates were determined by single-crystal XRD and the kinetics and thermodynamics of their formation and thermal decomposition reactions were also studied. The second system employs ethylenediamine as the Lewis base in combination with the R 3 Al (R = Me, Et) compounds. A 2:1 ratio of Et 3 Al with en yields a hydrocarbon-soluble, polymeric amide on thermolysis, which can be used to prepare AlN films by solution coating followed by pyrolysis in NH 3 . Lower proportions of R 3 Al to en, on thermolysis, lead to the formation of R m Al(en-2H) n cluster species that contain 5- and 6-coordinated Al atoms chelated and bridged by en-2H ligands. On further heating, these cluster species apparently go on to form cross-linked, insoluble, polymeric networks through condensation reactions involving the multiple N-H and R-Al groups on the periphery of the cluster molecules. The structures of two of these novel Al-en cluster compounds were determined by single-crystal XRD.
Numerical simulation of three dimensional transonic flows

The three-dimensional flow over a projectile has been computed using an implicit, approximately factored, partially flux-split algorithm. A simple composite grid scheme has been developed in which a single grid is partitioned into a series of smaller grids for applications which require an external large memory device such as the SSD of the CRAY X-MP/48 or multi-tasking. The accuracy and stability of the composite grid scheme have been tested by numerically simulating the flow over an ellipsoid at an angle of attack and comparing the solution with a single-grid solution. The flow field over a projectile at M = 0.96 and 1.1, and 4-deg angle of attack has been computed using a fine grid and compared with experiment.
A detailed analysis of how an urban trail system affects cyclists’ travel

Transportation specialists, urban planners, and public health officials have been steadfast in encouraging active modes of transportation over the past decades. Conventional thinking, however, suggests that providing infrastructure for cycling and walking in the form of off-street trails is critically important. An outstanding question in the literature is how one's travel is affected by the use of such facilities and specifically, the role of distance to the trail in using such facilities. This research describes a highly detailed analysis of use along an off-street facility in Minneapolis, Minnesota, USA. The core questions addressed in this investigation aim to understand relationships between: (1) the propensity of using the trail based on distance from the trip origin and destination, and (2) how far out of their way trail users travel for the benefit of using the trail and explanatory factors for doing so. The data used in the analysis for this research was collected as a human intercept survey along a section of an off-street facility. The analysis demonstrates that a cogent distance decay pattern exists and that the decay function varies by trip purpose. Furthermore, we find that bicyclists travel, on average, 67% longer in order to include the trail facility on their route. The paper concludes by explaining how the distance decay and shortest path versus taken path analysis can aid in the planning and analysis of new trail systems.
Give everyone a prize? Employee stock options in private venture-backed firms

This study examines employee stock options in private entrepreneurial companies. I focus on private U.S. venture-backed firms because they are renowned for the intensity and organizational depth of their stock option grants. Contrary to simple stereotype, however, I show that 27% of U.S. venture-backed firms do not grant stock options to all employees. I seek to explain this by theorizing that the economic and legal settings in which venture-backed companies exist lead to both costs and benefits from the use of stock options to attract, compensate, incent, monitor, and retain certain employees, and that sometimes the costs exceed the benefits. I test the theory by determining whether variation in the organizational depth to which venture-backed firms grant employee stock options can be explained by proxies for these economic and legal costs. Such proxies include the fraction of employees who are in technical positions; the degree of flatness in the firm's organizational structure; its proximity to other venture-backed companies; the number of patents it has been granted; and the fraction of equity held by venture investors. The results support the theory and thereby imply that venture-backed firms grant employee stock options in an economically sophisticated manner.
Index sets and presentations of complexity classes

This paper draws close connections between the ease of presenting a given complexity class b and the position of the index sets Ib = [lcub]i : L(Mi) ϵ b[rcub] and Jb = [lcub]i : Miis total ΛL(Mi) ∉ b[rcub] in the arithmetical hierarchy. For virtually all classes b studied in the literature, the lowest levels attainable are Ib ϵ ∑03 and Jb ϵ Π02; the first holds iff b is Δ02-presentable, and the second iff b is recursively presentable. A general kind of priority argument is formulated, and it is shown that every property enforcible by it is not recursively presentable. It follows that the classes of P-immune and P-biimmune languages in exponential time are not recursively presentable. It is shown that for all b with Ib ∉ ∑03, “many” members of b do not provably (in true Π2-arithmetic) belong to b. A class H is exhibited such that IH ϵ ∑03 is open, and IH ∉ ∑03 implies that the polynomial hierarchy is infinite.
On a result of Gelfand, Kapranov and Zelevinsky

Abstract In this paper we give new elementary proofs of basic results due to Gelfand, Kapranov, and Zelevinsky which express discriminants and results in terms of determinants of direct images of stably twisted Cayley–Koszul complexes of sheaves.
Cell blade based H.264 video encoding engine for large scale video surveillance applications

Video surveillance has become one of the most important tools for public safety and security. In this paper, we present our new work on developing efficient parallel computing algorithms and schemes for implementing H.264 video encoder engine on Cell Broadband Engine (CBE) blade for high performance large scale video surveillance applications. Extending our previous work on H.264 video encoding on CBE, we have developed new parallel computing schemes in computational load partition, dynamic task scheduling, motion estimation, and mode selection. We partition the intensive H.264 video encoding computation load into four major functional modules, namely, the pre-processing module, the motion estimation module, the mode selection and transform/quantization module, and the Context Adaptive Binary Arithmetic Coding (CABAC) module. The task scheduler dynamically assigns a waiting computing task to a SPE as soon as it becomes available. Our new implementation has achieved more than 5X performance improvement to encode 32 standard-definition (SD 720x480 pixel resolution) H.264 video streams simultaneously at 30 frames per second with one Cell Blade that consists of 16 Synergistic Processor Elements (SPEs) and two control Power Processor Elements (PPEs) or 448 SD channels of H.264 video streams on a single chassis Cell Blade Center with 14 Cell Blades.
Analytical solutions of the lattice Boltzmann BGK model

Analytical solutions of the two-dimensional triangular and square lattice Boltzmann BGK models have been obtained for the plane Poiseuille flow and the plane Couette flow. The analytical solutions are written in terms of the characteristic velocity of the flow, the single relaxation time τ, and the lattice spacing. The analytic solutions are the exact representation of these two flows without any approximation. Using the analytical solution, it is shown that in Poiseuille flow the bounce-back boundary condition introduces an error of first order in the lattice spacing. The boundary condition used by Kadanoffet al. in lattice gas automata to simulate Poiseuille flow is also considered for the triangular lattice Boltzmann BGK model. An analytical solution is obtained and used to show that the boundary condition introduces an error of second order in the lattice spacing.
Softening Instability: Part II—Localization Into Ellipsoidal Regions

Extending the preceding study of exact solutions for finite-size strain-softening regions in layers and infinite space, exact solution of localization instability is ob­ tained for the localization of strain into an ellipsoidal region in an infinite solid. The solution exploits Eshelby's theorem for eigenstrains in elliptical inclusions in an in­ finite elastic solid. The special cases of localization of strain into a spherical region in three dimensions and into a circular region in two dimensions are further solved for finite solids-spheres in 3D and circles in 2D. The solutions show that even if the body is infinite the localization into finite regions of such shapes cannot take place at the start of strain-softening (a state corresponding to the peak of the stress-strain diagram) but at a finite strain-softening slope. If the size of the body relative to the size of the softening region is decreased and the boundary is restrained, homogeneous strain-softening remains stable into a larger strain. The results also can be used as checks for finite element programs for strain-softening. The present solutions determine only stability of equilibration states but not bifurcations of the equilibrium path.
Titan: Polarimetric evidence for an optically thick atmosphere?

The disk-integrated polarization of Titan has been measured at phase angles ranging from 0.4 to 6.1 deg. The observed polarization is positive throughout this interval. This fact, when combined with published photometric data, suggests a model in which an optically thin Rayleigh atmosphere overlies an opaque cloud deck.
Fast on-line integer multiplication

A Turing machine multiplies binary integers on-line if it receives its inputs, low-order digit first, and produces the jth digit of the product before reading in the (j+1)st digits of the two inputs. We present a general method for converting any off-line multiplication algorithm which forms the product of two n-digit binary numbers in time F(n) into an on-line method which uses time only O(F(n) log n), assuming that F is monotone and satisfies n@?F(n)@?F(2n)/2@?kF(n) for some constant k. Applying this technique to the fast multiplication algorithm of Schonhage and Strassen gives an upper bound of O(n (log n)^2 loglog n) for on-line multiplication of integers. A refinement of the technique yields an optimal method for on-line multiplication by certain sparse integers. Other applications are to the on-line computation of products of polynomials, recognition of palindromes, and multiplication by a constant.
A simplified calculation for the fundamental solution to the heat equation on the Heisenberg group

Let L = −1/4 The purpose of this note is to present a simplified calculation of the Fourier transform of fundmental solution of theb-heat equation on the Heisenberg group. The Fourier transform of the fundamental solution has been computed by a number of authors (Gav77, Hul76, CT00, Tie06). We use the approach of (CT00, Tie06) and compute the heat kernel using Hermite functions but differ from the earlier approaches by working on a different, though biholomorphically equivalent, version of the Heisenberg group. The simplification in the computation occurs because the differential operators on this equivalent Heisenberg group take on a simpler form. Moreover, in the proof of Theorem 1.2, we reduce the n-dimensional heat equation to a 1-dimensional heat equation, and this technique would also be useful when analyzing the heat equation on the nonisotropic Heisenberg group (e.g., see (CT00)). We actually use the same version of the Heisenberg group as Hulanicki (Hul76), but he computes the fundamental solution of the heat equation associated to the sub-Laplacian and not the Kohn Laplacian acting on (0,q)-forms.
Observational introduction to the torus model

Abstract This space is far too small for even a cursory review of the observations connected with the torus model, and such reviews already exist (e.g. Antonucci, 1993). Instead I'll recount briefly how I got into this idea and discuss an outstanding puzzle; summarize recent key observations on the prototype NGC 1068; write a few words on the evidence for an extended featureless continuum source in AGN; and close with recent results for a prototype radio-loud object, namely Cygnus A, which seems to have a directly-resolved featureless continuum source.
Optical and Infrared Properties of the 2 Ms Chandra Deep Field North X-Ray Sources

We present an optical and near-infrared catalog for the X-ray sources in the ?2 Ms Chandra observation of the Hubble Deep Field North region. We have high-quality multicolor imaging data for all 503 X-ray point sources in the X-ray?selected catalog and reliable spectroscopic redshifts for 284. We spectroscopically identify six high-redshift (z > 1) type II quasars (L2?8keV > 1044 ergs s-1) in our sample. Our spectroscopic completeness for the R ? 24 sources is 87%. The spectroscopic redshift distribution shows two broad redshift spikes that have clearly grown over those originally seen in the ?1 Ms exposure. The spectroscopically identified extragalactic sources already comprise 75% of the measured 2?8 keV light. Redshift slices versus 2?8 keV flux show that an impressive 54% of the measured 2?8 keV light arises from sources at z 5.7 that would classify them as extremely red objects (EROs). The photometric redshifts of these EROs are all between z ~ 1.5 and z ~ 2.5. We use our wide wavelength coverage to determine rest-frame colors for the X-ray sources with spectroscopic or photometric redshifts. We find that many of the X-ray sources have the rest-frame colors of evolved red galaxies and that there is very little evolution in these colors with redshift. We also determine absolute magnitudes and find that many of the non?broad-line sources are more luminous than M, even at high redshifts. We therefore infer that deep X-ray observations may provide an effective way of locating M* galaxies with colors similar to present-day early-type galaxies to high redshifts.
Relationships between Bases of Power and Work Reactions: The Mediational Role of Procedural Justice

Though research has addressed relationships between social power bases and several work-related variables, processes that may underlie such relationships have generally not been examined. The present study considered relationships between bases of social power and subordinates’ afSective work reactions, hypothesizing that procedural justice would mediate such relationships. Two samples, one drawn from two service-oriented companies and one collected from a hospital, were used to test a mediational model rejlecting this hypothesis. Using theoretically grounded measures of social power and procedural justice, support was found for full mediation effects in connection with subordinates’ afSective work reactions. Implications regarding the development of social power bases are discussed.
Properties of dust in the martian atmosphere and its effect on temperature structure

Data from the Viking lander imaging experiment and the IRIS experiment on board the Mariner 9 Orbiter are used to develop a one-dimensional radiative-convective model to describe the Mars temperature profile. Photography was employed to determine the optical depth, mean size, shape, visible absorption coefficient, and vertical distribution of aerosols in the Mars atmosphere. The calculation procedures are outlined, particularly for the particle size distribution function, which indicated a cross-sectional average particle radius of 2.5 microns. Dust-free conditions in the atmosphere near the equator and at lower altitudes permit full surface absorption of sunlight and subsequent adiabatic lapse rates. Difficulties were encountered in accurately modeling temperature profiles to fit Viking lander data, and resultant variations are attributed to effects of both suspended dust particles and large scale circulation.
Population Genetics of Translational Robustness

Recent work has shown that expression level is the main predictor of a gene's evolutionary rate and that more highly expressed genes evolve slower. A possible explanation for this observation is selection for proteins that fold properly despite mistranslation, in short selection for translational robustness. Translational robustness leads to the somewhat paradoxical prediction that highly expressed genes are extremely tolerant to missense substitutions but nevertheless evolve very slowly. Here, we study a simple theoretical model of translational robustness that allows us to gain analytic insight into how this paradoxical behavior arises.
Saturn's Magnetosphere, Rings, and Inner Satellites

The discovery of the Saturn magnetosphere and its characterization by Pioneer 11 are reported, and findings on the planet's rings and satellites obtained by energetic charged particle measurements within the inner magnetosphere are presented. Bow shock crossings identified by the Pioneer plasma analyzer and magnetometer at distances of 24.1, 23.1 and 20.0 Saturn radii indicate the presence of a magnetosphere with physical dimensions and charged particle populations intermediate between those of the earth and Jupiter, with a scale more similar to that of the earth. Particle angular distributions on the inbound leg of the trajectory are consistent with a dipole magnetic field approximately perpendicular to the planet's equator, while on the outbound leg the distributions indicate the presence of an equatorial current sheet. Charged particle absorption features are detected at the orbits of Dione and Mimas, encompassing the orbits of Tethys and Enceladus, and at 2.534 and 2.343 Saturn radii indicating the presence of satellites of diameters greater than 170 km. Charged particle measurements also confirm the Pioneer division in the rings between 2.292 and 2.336 Saturn radii, a suspected satellite at 2.82 Saturn radii, the presence of the F ring between 2.336 and 2.371 Saturn radii and the outer radius of the A ring at 2.292 Saturn radii.
A conformally invariant sphere theorem in four dimensions

0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 1 An existence result . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 2 The proof of Theorem A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 3 A Weitzenbock formula for Bach–flat metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 4 The proof of Theorem C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
PHAST: Hardware-accelerated shortest path trees

Abstract We present a novel algorithm to solve the non-negative single-source shortest path problem on road networks and graphs with low highway dimension. After a quick preprocessing phase, we can compute all distances from a given source in the graph with essentially a linear sweep over all vertices. Because this sweep is independent of the source, we are able to reorder vertices in advance to exploit locality. Moreover, our algorithm takes advantage of features of modern CPU architectures, such as SSE and multiple cores. Compared to Dijkstra’s algorithm, our method needs fewer operations, has better locality, and is better able to exploit parallelism at multi-core and instruction levels. We gain additional speedup when implementing our algorithm on a GPU, where it is up to three orders of magnitude faster than Dijkstra’s algorithm on a high-end CPU. This makes applications based on all-pairs shortest-paths practical for continental-sized road networks. Several algorithms, such as computing the graph diameter, arc flags, or exact reaches, can be greatly accelerated by our method.
Bandwidth of the product of paths of the same length

In this note we give a numerical expression for the bandwidth bw(P"n^d) of the d-product of a path with n edges, P"n^d. We prove that this bandwidth is given by the sum of certain multinomial coefficients. We also show that bw(P"n^d) is bounded above and below by the largest coefficient in the expansion of (1+x+...+x^n)^k, with k@?{d,d+1}. Moreover, we compare the asymptotic behavior of bw(P"n^d) with the bandwidth of the labeling obtained by ordering the vertices of P"n^d in lexicographic order.
Design and synthesis of selective mesoporous anion traps

Arsenic contamination of groundwater has recently commanded widespread public attention. Under many conditions, arsenic, and certain other environmentally relevant toxic metals such as chromium, exist in nature as oxyanions. Selective binding of anions is one of the most challenging problems in chemistry, biology, and materials and environmental science. In this paper we report the synthesis and use of metal-chelated ligands immobilized on mesoporous silica as novel anion binding materials. Nearly complete removal of arsenate and chromate has been achieved in the presence of competing anions for solutions containing more than 100 mg/L (ppm) toxic metal anions under a variety of conditions. Anion loading of more than 120 mg (anion)/g of adsorption materials is observed. A binding mechanism is also proposed on the basis of computer modeling. First, Cu(II) ions are bonded to ethylenediamine (EDA) ligands to form octahedral complexes on the surface of the mesoporous silica. This gives rise to positively charg...
Is It Still Considered Reading? Using Digital Video Storytelling to Engage Adolescent Readers

Abstract In order to comprehend and ultimately enjoy reading a text, a reader must first be engaged in it. However, many high school students have difficulty engaging with texts for a variety of reasons. This study was interested in innovative solutions to this problem and examined the educational and aesthetic value of a particular digital video reading aid designed to help engage high school students in reading literature. Results suggested that this reading solution did indeed engage these students in the text while also helping them comprehend, critically analyze, and enjoy the reading experience as a whole. Additionally, these students positively responded to a bonus literature discussion section, thereby suggesting their desire to co-construct meanings with other readers.
Measurements of electron density and plasma current distributions in Tokamak plasma

A submillimeter-wave, phase-modulated polarimeter/interferometer is used for simultaneous time-dependent measurement of line-averaged electron density and poloidal field-induced Faraday rotation along chords of the plasma column in ISX-B tokamak. Heterodyne detection and hollow dielectric waveguide are utilized to achieve the high sensitivity required for the multichord experiment. A data analysis code has been developed to reconstruct the asymmetric distributions of plasma density. The validity of the code is examined, and the result shows good agreement with density profiles measured by Thomson scattering.
Rosat x-ray observations of the cooling flow cluster a2597

The cluster A2597 was observed in X-rays with the ROSAT PSPC and HRI detectors. The X-ray emission from the cluster extends out to a radius of at least 2.37 Mpc. The X-ray isophotes are oriented similarly to the optical isophotes of the central cD galaxy and to the isopleths of the galaxy distribution in the cluster but are otherwise quite regular, which suggests that this cluster is reasonably relaxed and in hydrostatic equilibrium. The merged HRI and PSPC surface brightness profile is not adequately fitted by a beta model because of the central X-ray surface brightness peak, which indicates the presence of a cooling flow. If the central 108'' in radius are excluded, an acceptable fit is found that gives β = 0.64+ 0.08−0.03 but only an upper limit to the core radius, rcore < 78''. The gas density and accumulated mass were derived as a function of radius, and the hydrostatic equilibrium condition was used to determine the total gravitational mass, also as a function of radius. Within a radius of 2 Mpc, we found masses of Mgas = 1.2 × 1014 M☉ and Mtot = 5.6 × 1014 M☉, and a gas mass fraction of about 21%. However, our poor knowledge of the spatial variation of the gas temperature makes the total mass values uncertain by at least a factor of 2. The ROSAT PSPC X-ray spectrum of the cluster was determined. Both the overall cluster spectrum and the spatially resolved spectra within 300 kpc require the presence of both hot gas and a cooling flow in the spectrum. The spectrally determined total cooling rate of = 344+ 75−67 M☉ yr-1 is in good agreement with those derived from analyses of the X-ray surface brightness profile from the Einstein IPC and the ROSAT HRI images. The ROSAT spatially resolved X-ray spectra indicate that the cooling component is distributed over the inner ~300 kpc in radius of the cluster. The presence of the cooling flow in the central regions and poorer statistics in the outer regions prevent us from deriving an accurate profile for the variation of the ambient cluster gas temperature. We do not detect any significant excess X-ray absorption toward the center of A2597, and we set a very conservative upper limit on the excess column in front of the cooling flow region of ΔNH < 1.72 × 1020 cm-2. A2597 is one of the few cooling flows toward which a large column has been detected in radio observations (O'Dea et al.). A total column of NH ≈ 1 × 1021 cm-2 was seen in 21 cm absorption against the very small central radio source. Our X-ray upper limit is not inconsistent with the 21 cm detection if the absorber covers only the small region ( ~6'') occupied by the radio source. However, we can rule out an absorber with a uniform column that covers the entire cooling flow or even just the smaller region of the extended optical emission-line nebula.
Polyphosphazenes: Thermomechanical transitions

Four linear phosphazene homopolymers with structure [NPX2]n, where X = Cl, OCH2CF3, OCH2C3F7, and OCH2C3F6CHF2, two copolymers with mole ratios of the alkoxy substituents OCH2CF3/OCH2C3F7 and OCH2CF3/OCH2C3F6CHF2 approximately 1/1, and two physical blends with overall compositions approximating those of the copolymers were examined between −180° and 250°C in an inert atmosphere using a fully automated torsional braid apparatus. Crystal/melt, crystal/crystal, glass, and glassy-state transitions are documented on the basis of the thermomechanical experiments. In addition to the assignment of transition temperatures, the noteworthy findings include the narrow range of values of the glass transition temperatures of the four homopolymers, the increasing negative slope of the modulus versus temperature in the glassy state with increasing size of the substitutent, the presence of a transition immediately above Tg for the copolymers, and the incompatibility of the blends. A glassy-state transition in each of the fluoroalkoxypolyphosphazene materials is tentatively attributed to motion of the substituents. An additional glassy-state transition occurs in the heptafluorobutoxy- and octafluoropentoxy-substituted materials. The transition temperatures of specimens preheated to 250°C were essentially the same as those preheated to 150°C.
Noncommuting observables and local realism

Abstract A standard approach in the foundations of quantum mechanics studies local realism and hidden variables models exclusively in terms of violations of Bell-like inequalities. Thus quantum nonlocality is tied to the celebrated no-go theorems, and these comprise a long list that includes the Kochen–Specker and Bell theorems, as well as elegant refinements by Mermin, Peres, Hardy, GHZ, and many others. Typically entanglement or carefully prepared multipartite systems have been considered essential for violations of local realism and for understanding quantum nonlocality. Here we show, to the contrary, that sharp violations of local realism arise almost everywhere without entanglement. The pivotal fact driving these violations is just the noncommutativity of quantum observables. We demonstrate how violations of local realism occur for arbitrary noncommuting projectors, and for arbitrary quantum pure states. Finally, we point to elementary tests for local realism, using single particles and without reference to entanglement, thus avoiding experimental loopholes and efficiency issues that continue to bedevil the Bell inequality related tests.
IRAS-based whole-sky upper limit on Dyson Spheres

A Dyson Sphere is a hypothetical construct of a star purposely cloaked by a thick swarm of broken-up planetary material to better utilize all of the stellar energy. A clean Dyson Sphere identification would give a significant signature for intelligence at work. A search for Dyson Spheres has been carried out using the 250,000 source database of the IRAS infrared satellite which covered 96% of the sky. The search has used the Calgary data collection of the IRAS Low Resolution Spectrometer (LRS) to look for fits to blackbody spectra. Searches have been conducted for both pure (fully cloaked) and partial Dyson Spheres in the blackbody temperature region 100 {le} T {le} 600 K. Other stellar signatures that resemble a Dyson Sphere are reviewed. When these signatures are used to eliminate sources that mimic Dyson Spheres very few candidates remain and even these are ambiguous. Upper limits are presented for both pure and partial Dyson Spheres. The sensitivity of the LRS was enough to find solar-sized Dyson Spheres out to 300 pc, a reach that encompasses a million solar-type stars.
One-pot copper-catalyzed synthesis of N-functionalized pyrazoles from boronic acids

A straight-forward route to prepare a diverse set of N-aryl pyrazoles via a one-pot copper-catalyzed boronic acid coupling and cyclization protocol is presented. A variety of aryl and heteroaryl N-functionalized pyrazoles not easily accessible by other means were formed in good yield from readily available boronic acid precursors in an operationally simple procedure.
8-(6-Aminohexyl) amino-cyclic ATPR : A new affinity probe for the study of cyclic ADPR-binding proteins

Abstract 8-(6-Aminohexyl) amino-cyclic ATPR, a new affinity probe for the study of cADPR-binding proteins, was prepared in four steps with an overall yield of 21%.
Ownership and the Temptation to Loot: Evidence from Privatized Firms in the Czech Republic

Abstract Using a new dataset on firms privatized in the Czech Republic from 1993 to 1996, we show that, even after controlling for size and structure, voucher-privatized joint stock companies perform worse than firms with concentrated shareholdings that had to be purchased for cash, i.e., limited liability companies and foreign joint stock companies. We argue that static asset stripping, or tunneling in Czech parlance, was combined with dynamic looting of the Akerlof and Romer (1993) type because these same joint stock companies had privileged access to soft credit from state controlled banks. Although we do not have direct evidence of looting, we show that liabilities increased at a much faster rate in joint stock companies than in limited liability companies. J. Comp. Econ. , March 2002, 30 (1), pp. 1–24. World Bank, Washington, DC. © 2002 Elsevier Science (USA). Journal of Economic Literature Classification Numbers: L2, G3, K4.
Friction estimation technique for Galileo scan platform control

A friction estimation technique has been developed for the scan platform control of the Galileo spacecraft. The purpose of the estimation is to reduce the impact of friction in the scan platform actuator on the pointing performance of the scan platform so that tight pointing requirements can be met. The estimator operates by comparing the actual behavior of the platform with the expected behavior and attributing the difference to the presence of friction. The estimator is coupled with a proportional-integral-derivative controller to generate a control torque for the scan platform actuator. Since the algorithm will be implemented on an onboard digital computer, a stability analysis of the estimator-controller in discrete time is presented. The performance of the design is demonstrated by a sample slew test case.
Adjustment Dynamics and Rational Play in Games

When a given strategic situation arises repeatedly, the possibility arises that equilibrium predictions can be justified by a dynamic adjustment process. We examine myopic adjustment dynamics, a class that includes replicator dynamics from evolutionary game theory, simple models of imitation, models of experimentation and adjustment, and some simple learning dynamics. We present a series of theorems showing conditions under which behavior that is asymptotically stable under some such dynamic is strategically stable in the sense of Kohlberg and Mertens. This behavior is thus as if the agents in the economy satisfied the extremely stringent assumptions that game theory traditionally makes about rationality and beliefs. Journal of Economic Literature Classification Number: C72.