cssi/SciSciGPT-SciSciNet huggingface dataset:
Jet Vetoes interfering with H → WW

Far o�-shell Higgs production in H ! WW;ZZ, is a particularly powerful probe of Higgs properties, allowing one to disentangle Higgs width and coupling information unavailable in on-shell rate measurements. These measurements require an understanding of the cross section in the far o�-shell region in the presence of realistic experimental cuts. We analytically study the eect of a pT jet veto on far o�-shell cross sections, including signal-background interference, by utilizing hard functions in the soft collinear eective theory that are dierential in the decay products of the W=Z. Summing large logarithms of MWW=p veto , wend that the jet veto induces a strong dependence on MWW , modifying distributions in MWW and MT . The example of gg! H! WW is used to demonstrate these eects at next to leading log order. We also discuss the importance of jet vetoes and jet binning for the recent program to extract Higgs couplings and widths from far o�-shell cross sections.
Two-Step Synthesis of Furans by Mn(III)-Promoted Annulation of Enol Ethers.

Enol ethers, β-dicarbonyl compounds and the Mn(III) reagent Mn3O(OAc)7 react under mild conditions to form 1-alkoxy-1.2-dihydrofurans in good (70–98%) yields. The latter are readily converted to furans by acid-catalyzed elimination of ROH.
The modified gain extended Kalman filter and parameter identification in linear systems

Abstract For a special class of systems, a general formulation and stochastic stability analysis of a new nonlinear filter, called the modified gain extended Kalman filter (MGEKF), is presented. Used as an observer, it is globally exponentially convergent. In the presence of uncertainties a nominal nonrealizable filter algorithm is developed for which global stochastic stability is proven. With respect to this nominal filter algorithm, conditions are obtained such that the effective deviations of the realizable filter are not destabilizing. In an appropriate coordinate frame, the parameter identification problem of a linear system is shown to be a member of this special class. For the example problems, the MGEKF shows superior convergence characteristics without evidence of instability.
Design, Installation, and Commissioning of the DØ Overpass at the Fermilab Main Ring

In order to accommodate large detectors for p?p studies at the Tevatron, the Main Ring has been modified to be non-planar. A 700 foot-long portion of the ring has been reworked to create an overpass which displaces the beam orbit upwards by 51 inches at the DO long straight section.1 The overpass region follows the "screw" geometry proposed by T. Collins.2 A set of four vertically bending dipoles were inserted into the Main Ring lattice; they are powered on a separate bus and operate at twice the current and field level of a standard bend. To make space for these vertical bends, at each vertical bend point two of the four standard dipoles in a half-cell are removed and the other two are powered at twice the current and field level of the rest of the ring. The vertical bends also have a set of trim coils powered by a separate supply so that any difference in the horizontal and vertical bending strengths can be compensated.3 The DO overpass was commissioned with beam in November-December 1984. The principal effect on beam dynamics - predicted and observed - is the introduction of momentum dispersion in the vertical dimension of peak value 1.9m. To preserve closed orbit quality during acceleration, the vertical bends must track the rest of the ring with a precision of better than 0.1%.
Diffusion approximation for an overloaded X model via a stochastic averaging principle

In previous papers we developed a deterministic fluid approximation for an overloaded Markovian queueing system having two customer classes and two service pools, known in the call-center literature as the X model. The system uses the fixed-queue-ratio-with-thresholds (FQR-T) control, which we proposed as a way for one service system to help another in face of an unexpected overload. Under FQR-T, customers are served by their own service pool until a threshold is exceeded. Then, one-way sharing is activated with customers from one class allowed to be served in both pools. The control aims to keep the two queues at a pre-specified fixed ratio. We supported the fluid approximation by establishing a functional weak law of large numbers involving a stochastic averaging principle. In this paper we develop a refined diffusion approximation for the same model based on a many-server heavy-traffic functional central limit theorem.
Out-of-core sort-first parallel rendering for cluster-based tiled displays

We present a sort-first parallel system for out-of-core rendering of large models on cluster-based tiled displays. The system renders high-resolution images of large models at interactive frame rates using off-the-shelf PCs with small memory. Given a model, we use an out-of-core preprocessing algorithm to build an on-disk hierarchical representation for the model. At run time, each PC renders the image for a display tile, using an out-of-core rendering approach that employs multiple threads to overlap rendering, visibility computation, and disk operations. The system can operate in approximate mode for real-time rendering, or in conservative mode for rendering with guaranteed accuracy. Running our system in approximate mode on a cluster of 16 PCs each with 512 MB of main memory, we are able to render 12-megapixel images of a 13-million-triangle model with 99.3% of accuracy at 10.8 frames per second. Rendering such a large model at high resolutions and interactive frame rates would typically require expensive high-end graphics hardware. Our results show that a cluster of inexpensive PCs is an attractive alternative to those high-end systems.
Hop-by-hop congestion control over a wireless multi-hop network

This paper focuses on congestion control over multi-hop, wireless networks. In a wireless network, an important constraint that arises is that due to the MAC (Media Access Control) layer. Many wireless MACs use a time-division strategy for channel access, where, at any point in space, the physical channel can be accessed by a single user at each instant of time. In this paper, we develop a fair hop-by-hop congestion control algorithm with the MAC constraint being imposed in the form of a channel access time constraint, using an optimization-based framework. In the absence of delay, we show that this algorithm are globally stable using a Lyapunov-function-based approach. Next, in the presence of delay, we show that the hop-by-hop control algorithm has the property of spatial spreading. In other words, focused loads at a particular spatial location in the network get "smoothed" over space. We derive bounds on the "peak load" at a node, both with hop-by-hop control, as well as with end-to-end control, show that significant gains are to be had with the hop-by-hop scheme, and validate the analytical results with simulation.
Aspects of Gauge Theory on Commutative and Noncommutative Tori

We study aspects of gauge theory on tori which are a consequences of Morita equivalence. In particular we study the behavior of gauge theory on non-commutative tori for arbitrarily close rational values of Θ. For such values of Θ, there are Morita equivalent descriptions in terms of Yang-Mills theories on commutative tori with very different magnetic fluxes and rank. In order for the correlators of open Wilson lines to depend smoothly on Θ, the correlators of closed Wilson lines in the commutative Yang-Mills theory must satisfy strong constraints. If exactly satisfied, these constraints give relations between small and large N gauge theories. We verify that these constraints are obeyed at leading order in the 1/N expansion of pure 2-d QCD and of strongly coupled = 4 super Yang-Mills theory.
Earliest stages of protocluster formation: Substructure and kinematics of starless cores in Orion

We study the structure and kinematics of nine 0.1 pc scale cores in Orion with the IRAM 30 m telescope and at higher resolution eight of the cores with CARMA, using CS(2-1) as the main tracer. The single-dish moment zero maps of the starless cores show single structures with central column densities ranging from 7 to 42 Multiplication-Sign 10{sup 23} cm{sup -2} and LTE masses from 20 M{sub Sun} to 154 M{sub Sun }. However, at the higher CARMA resolution (5''), all of the cores except one fragment into 3-5 components. The number of fragments is small compared to that found in some turbulent fragmentation models, although inclusion of magnetic fields may reduce the predicted fragment number and improve the model agreement. This result demonstrates that fragmentation from parsec-scale molecular clouds to sub-parsec cores continues to take place inside the starless cores. The starless cores and their fragments are embedded in larger filamentary structures, which likely played a role in the core formation and fragmentation. Most cores show clear velocity gradients, with magnitudes ranging from 1.7 to 14.3 km s{sup -1} pc{sup -1}. We modeled one of them in detail, and found that its spectra are best explained by amore » converging flow along a filament toward the core center; the gradients in other cores may be modeled similarly. We infer a mass inflow rate of {approx}2 Multiplication-Sign 10{sup -3} M{sub Sun} yr{sup -1}, which is in principle high enough to overcome radiation pressure and allow for massive star formation. However, the core contains multiple fragments, and it is unclear whether the rapid inflow would feed the growth of primarily a single massive star or a cluster of lower mass objects. We conclude that fast, supersonic converging flow along filaments play an important role in massive star and cluster formation.« less
Characterizing multi-planet systems with classical secular theory

Classical secular theory can be a powerful tool to describe the qualitative character of multi-planet systems and offer insight into their histories. The eigenmodes of the secular behavior, rather than current orbital elements, can help identify tidal effects, early planet–planet scattering, and dynamical coupling among the planets, for systems in which mean-motion resonances do not play a role. Although tidal damping can result in aligned major axes after all but one eigenmode have damped away, such alignment may simply be fortuitous. An example of this is 55 Cancri (orbital solution of Fischer et al. in Astophys J 675:790–801, 2008) where multiple eigenmodes remain undamped. Various solutions for 55 Cancri are compared, showing differing dynamical groupings, with implications for the coupling of eccentricities and for the partitioning of damping among the planets. Solutions for orbits that include expectations of past tidal evolution with observational data, must take into account which eigenmodes should be damped, rather than expecting particular eccentricities to be near zero. Classical secular theory is only accurate for low eccentricity values, but comparison with other results suggests that it can yield useful qualitative descriptions of behavior even for moderately large eccentricity values, and may have advantages for revealing underlying physical processes and, as large numbers of new systems are discovered, for triage to identify where more comprehensive dynamical studies should have priority.
False data injection attacks against state estimation in electric power grids

A power grid is a complex system connecting electric power generators to consumers through power transmission and distribution networks across a large geographical area. System monitoring is necessary to ensure the reliable operation of power grids, and state estimation is used in system monitoring to best estimate the power grid state through analysis of meter measurements and power system models. Various techniques have been developed to detect and identify bad measurements, including interacting bad measurements introduced by arbitrary, nonrandom causes. At first glance, it seems that these techniques can also defeat malicious measurements injected by attackers.In this article, we expose an unknown vulnerability of existing bad measurement detection algorithms by presenting and analyzing a new class of attacks, called false data injection attacks, against state estimation in electric power grids. Under the assumption that the attacker can access the current power system configuration information and manipulate the measurements of meters at physically protected locations such as substations, such attacks can introduce arbitrary errors into certain state variables without being detected by existing algorithms. Moreover, we look at two scenarios, where the attacker is either constrained to specific meters or limited in the resources required to compromise meters. We show that the attacker can systematically and efficiently construct attack vectors in both scenarios to change the results of state estimation in arbitrary ways. We also extend these attacks to generalized false data injection attacks, which can further increase the impact by exploiting measurement errors typically tolerated in state estimation. We demonstrate the success of these attacks through simulation using IEEE test systems, and also discuss the practicality of these attacks and the real-world constraints that limit their effectiveness.
Chloroaluminum sulfonated phthalocyanine versus dihematoporphyrin ether: Early vascular events in the rat window chamber

The development of a simple and well-tolerated rat window chamber has allowed direct comparison of the vascular effects of two photosensitizers, chloroaluminum sulfonated phthalocyanine (CASP) and dihematoporphyrin ether (DHE). CASP and DHE were given 4 days after the implantation of the window chamber. Photodynamic therapy (PDT) with CASP was performed 24 hours after intravenous injection (10 mg/kg) with light at 675 nm (power density 200 mW/cm2, incident energy 100 J). DHE was given in a similar fashion (5 mg/kg intraperitoneally; light at 630 nm with matching power density and energy settings 24 hours after injection). Using videomicroscopic and integrating sphere measurements, marked differences were noted in the vascular effects of these photosensitizers. DHE caused immediate hemorrhage and disruption of the postcapillary venules, while CASP induced vascular spasm starting 4 hours after the completion of PDT. Forty-eight hours after PDT, both systems demonstrated a loss of chamber-induced neovascularization.
Internal versus External Capital Markets

This paper presents a framework for analyzing the costs and benefits of internal versus external capital allocation. We focus pritnarily on comparing an internal capital market with bank lending. While both represent centralized forms of financing, in the former case the financing is owner-provided, while in the latter ceise it is not. We argue that the ownership aspect of internal capital allocation has three important consequences: (1) it leads to more monitoring than bank lending; (2) it reduces managers' entrepreneurial incentives; and (3) it makes it easier to efficiently redeploy the assets of projects that are performing poorly under existing management.
Embeddings in the 3/4 range

We give a complete obstruction to turning an immersion f : M m → R n into an embedding when 3n ≥ 4m + 5. It is a secondary obstruction, and exists only when the primary obstruction, due to Andre Haefliger, vanishes. The obstruction lives in a twisted cobordism group, and its vanishing implies the existence of an embedding in the regular homotopy class of f in the range indicated. We use Tom Goodwillie's calculus of functors, following Michael Weiss, to help organize and prove the result.
Robust time-delay control of multimode systems

This paper presents a procedure for the design of open loop controllers for flexible structures using multiple step inputs delayed in time. The controller attenuates the residual vibration by cancelling the complex poles of the system. Robustness is achieved by locating additional zeros at the cancelled poles of the system. The paper begins by addressing the control of a single mode and examines the effect of user selected time-delays on robustness and the reference input. Next, a procedure for the design of robust time-delay controllers for multiple modes with user selected time-delays is considered. This is followed by a design of a minimum time-delay controller, such that the step input magnitudes are constrained to values between 0 and 1. Two examples, a spring-mass system and a single-link flexible-arm robot are used to illustrate the effectiveness of the proposed controller.
The upper critical field of untwinned YBa2Cu3O7−δ crystals

Abstract The upper critical field of untwinned YBa2Cu3O7-δ crystals is determined from the onset of diamagnetism in dc-magnetization measurements. There is no evidence of anisotropy in the upper critical field in the basal plane indicating that the ordering of oxygen into chains plays only a minor role in the mechanism leading to superconductivity. The slopes of the upper critical field are −1.8T/K for the c-direction and −10 T/K for the a, b-direction.
Boundary terms, spinors and Kerr/CFT

Similarly as in AdS/CFT, the requirement that the action for spinors be stationary for solutions to the Dirac equation with fixed boundary conditions determines the form of the boundary term that needs to be added to the standard Dirac action in Kerr/CFT. We determine this boundary term and make use of it to calculate the two-point function for spinor fields in Kerr/CFT. This two-point function agrees with the correlator of a two dimensional relativistic conformal field theory.
Automorphic orbits in free groups

Abstract Let Fn be the free group of a finite rank n. We study orbits Orbφ(u), where u is an element of the group Fn, under the action of an automorphism φ. If an orbit like that is finite, we determine precisely what its cardinality can be if u runs through the whole group Fn, and φ runs through the whole group Aut(Fn). Another problem that we address here is related to Whitehead's algorithm that determines whether or not a given element of a free group of finite rank is an automorphic image of another given element. It is known that the first part of this algorithm (reducing a given free word to a free word of minimum possible length by elementary Whitehead automorphisms) is fast (of quadratic time with respect to the length of the word). On the other hand, the second part of the algorithm (applied to two words of the same minimum length) was always considered very slow. We give here an improved algorithm for the second part, and we believe this algorithm always terminates in polynomial time with respect to the length of the words. We prove that this is indeed the case if the free group has rank 2.
A Thermal Bremsstrahlung Model for the Quiescent X-Ray Emission from Sagittarius A*

I consider the thermal bremsstrahlung emission from hot accretion flows (Bondi/ADAFs), taking into account the finite size of the observing telescope's beam (Rbeam) relative to the Bondi accretion radius (RA). For Rbeam RA, soft X-ray emission from the hot interstellar medium surrounding the black hole dominates the observed emission, while for Rbeam RA, hard X-ray emission from the accretion flow dominates. I apply these models to Chandra observations of the Galactic center, for which Rbeam ≈ RA. I argue that bremsstrahlung emission accounts for most of the "quiescent" (nonflaring) flux observed by Chandra from Sgr A*; this emission is spatially extended on scales ~RA ~ 1'' and has a relatively soft spectrum, as is observed. If accretion onto the central black hole proceeds via a Bondi or ADAF flow, a hard X-ray power law should be present in deeper observations with a flux ~ of the soft X-ray flux; nondetection of this hard X-ray component would argue against ADAF/Bondi models. I briefly discuss the application of these results to other low-luminosity active galactic nuclei.
Some Singular Limit Laminations of Embedded Minimal Planar Domains

In this paper we give two examples of sequences of embedded minimal planar domains in $\mathbb{R}^3$ which converge to singular laminations of $\mathbb{R}^3$. In contrast with the situation for embedded minimal disks, these examples do not arise from complete embedded minimal planar domains and highlight some of the subtleties inherent in understanding refined properties of embedded minimal planar domains.
Experimental Robust Control of Structural Acoustic Radiation

This work addresses the design and application of robust controllers for structural acoustic control. Both simulation and experimental results are presented. H(infinity) and mu-synthesis design methods were used to design feedback controllers which minimize power radiated from a panel while avoiding instability due to unmodeled dynamics. Specifically, high order structural modes which couple strongly to the actuator-sensor path were poorly modeled. This model error was analytically bounded with an uncertainty model, which allowed controllers to be designed without artificial limits on control effort. It is found that robust control methods provide the control designer with physically meaningful parameters with which to tune control designs and can be very useful in determining limits of performance. Experimental results also showed, however, poor robustness properties for control designs with ad-hoc uncertainty models. The importance of quantifying and bounding model errors is discussed.
Implausible consequences of superstrong nonlocality

We look at the consequences of so-called `superstrong nonlocal correlations', which are hypothetical violations of Bell/CHSH inequalities that are stronger than quantum mechanics allows while still preventing the possibility of instantaneous communication. It is shown that the existence of maximally superstrong correlated bits implies that all distributed computations can be performed with a trivial amount of communication, i.e. with one bit. If one believes that Nature does not allow such a computational `free lunch', then this result gives a reason why superstrong correlation are indeed not possible.
Decolorization kinetics of the azo dye reactive red 2 under methanogenic conditions: effect of long-term culture acclimation.

The biological decolorization of the textile azo dye Reactive Red 2 was investigated using a mixed, mesophilic methanogenic culture, which was developed with mixed liquor obtained from a mesophilic, municipal anaerobic digester and enriched by feeding a mixture of dextrin/peptone as well as media containing salts, trace metals and vitamins. Batch decolorization assays were conducted with the unacclimated methanogenic culture and dye decolorization kinetics were determined as a function of initial dye, biomass, and carbon source concentrations. Dye decolorization was inhibited at initial dye concentrations higher than 100 mg l-1 and decolorization kinetics were described based on the Haldane model. The effect of long-term culture exposure to the reactive dye on decolorization kinetics, culture acclimation, as well as possible dye mineralization was tested using two reactors fed weekly for two years with an initial dye concentration of 300 mg l-1 and a mixture of dextrin/peptone. The maximum dye decolorization rate after a 2-year acclimation at an initial dye concentration of 300 mg l-1 was more than 10-fold higher as compared to that obtained with the unacclimated culture. Aniline and the o-aminohydroxynaphthalene derivative resulting from the reductive azo bond cleavage of the dye were detected, but further transformation(s) leading to dye mineralization were not observed. Reactive Red 2 did not serve as the carbon and energy source for the mixed culture, and dye decolorization was sustained by the continuous addition of dextrin and peptone. Thus, biological decolorization of reactive azo dyes is feasible under conditions of low redox potential created and maintained in overall methanogenic systems, but supply of a biodegradable carbon source is necessary.
Recent Advances on the Synthesis and Chemistry of Carbaporphyrins and Related Porphyrinoid Systems

Synthetic methods have been developed for the efficient synthesis of meso-unsubstituted carbaporphyrinoid systems, including oxybenziporphyrins, benzocarbaporphyrins, tropiporphyrins, and azuliporphyrins. In addition, meso-tetrarylporphyrinoids are available by using modified Lindsey–Rothemund reaction conditions. These porphyrin analogs show a broad spectrum of aromatic properties that range from nonaromatic benziporphyrins to highly diatropic systems such as benzocarbaporphyrins. Carbaporphyrinoid systems exhibit unusual reactivity and are often capable of generating organometallic derivatives under mild conditions. Many of the trends observed in the carbaporphyrinoid series were also evident for an expanded series of carbasapphyrins as well. Syntheses of dicarbaporphyrinoids have been investigated but it remains to be seen whether these studies will eventually lead to the formation of hydrocarbon analogs of the porphyrins.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Statistics of natural images: Scaling in the woods.

We study the statistics of an ensemble of images taken in the woods. Distributions of local quantities such as contrast are scale invariant and have nearly exponential tails. Power spectra exhibit scaling with a nontrivial exponent. These data limit the information content of natural images and point to the importance of gain-control strategies in visual processing.
Boundary S matrices with N=2 supersymmetry

Abstract We propose the exact boundary S matrix for breathers of the N =2 supersymmetric sine-Gordon model. We argue that this S matrix has three independent parameters, in agreement with a recently-proposed action. We also show, contrary to a previous claim, that the “universal” supersymmetric boundary S matrix commutes with two supersymmetry charges. General N =2 supersymmetric boundary integrable models are expected to have boundary S matrices with a similar structure.
Coronal polar plumes

The purpose of this investigation was to determine what connection exists between coronal plumes and polar surface features. To this end the properties of plumes were re-examined by making a detailed statistical analysis of photographs of three eclipses (1962, 1963, and 1965) of the last sunspot minimum. It is found that a ‘typical’ plume has a core density ≈ 108 cm−3, a half width ≈ 3.3 × 104km, and a density profile with distance r from its axis characterized by $$N \approx {\text{10}}^{\text{8}} \left( {1 - \frac{r}{{3.9 \times 10^4 }}} \right)^{1.6} $$ There is some (although only weak) regularity in the projected spacing of plumes with a mean separation of ≈ 7 × 104 km. The relation between plumes and various surface features is examined. Although little direct evidence can be assembled, we conclude that a direct connection exists between plumes and photospheric faculae, bright K3 faculae, and the small-scale magnetic structure present in the chromospheric network. It is hypothesized that plumes originate at the bright cores of the rosettes which lie along the chromospheric network. The distribution of magnetic field in the corona above a surface covered with idealized chromospheric network cells is calculated. The fact that the shape and size of the magnetic flux tubes originating from the rosette agrees with that of observed plumes supports the hypothesis.
Toward automated discovery of artistic influence

Considering the huge amount of art pieces that exist, there is valuable information to be discovered. Examining a painting, an expert can determine its style, genre, and the time period that the painting belongs. One important task for art historians is to find influences and connections between artists. Is influence a task that a computer can measure? The contribution of this paper is in exploring the problem of computer-automated suggestion of influences between artists, a problem that was not addressed before in a general setting. We first present a comparative study of different classification methodologies for the task of fine-art style classification. A two-level comparative study is performed for this classification problem. The first level reviews the performance of discriminative vs. generative models, while the second level touches the features aspect of the paintings and compares semantic-level features vs. low-level and intermediate-level features present in the painting. Then, we investigate the question "Who influenced this artist?" by looking at his masterpieces and comparing them to others. We pose this interesting question as a knowledge discovery problem. For this purpose, we investigated several painting-similarity and artist-similarity measures. As a result, we provide a visualization of artists (Map of Artists) based on the similarity between their works
The Cohomology of the Lyons Group and Double Covers of Alternating Groups

From the Classification Theorem for Finite Simple Groups we know that there are precisely eight sporadic simple groups which have (Z/2) as their largest elementary abelian 2–subgroup (i.e. they have rank equal to four at the prime p = 2): the two Mathieu groups M22, M23; the two Janko groups J2, J3; the McLaughlin group McL; the Lyons group Ly; and two groups with much larger 2-Sylow subgroups HS (Higman–Sims) and Co3 (one of Conway’s groups). In previous work the mod 2 cohomology rings of M22 [AM2], M23 [M], J2 and J3 [CMM], and McL [AM3] were computed. One of the main objectives of this paper is to determine the cohomology ring H(Ly;F2). Even though Ly is a large and complicated group (it is the largest of those in the list of above, having order equal to 51, 765, 179, 004 × 10), the answer turns out to be surprisingly simple. We show that Ly has two conjugacy classes of maximal 2-elementary subgroups, one 2 with Weyl group A7, and one 2 3 with Weyl group L3(2), and we prove that these subgroups detect H∗(Ly). In [AM4] we determined the ring of invariants H∗(24)A7 = F2[d8, d12, d14, d15](1, a18, a20, a21, a24, a25, a27, a45) while it is well–known that the invariants H∗(23)L3(2) are F2[d4, d6, d7], the Dickson algebra. From this we obtain
Total synthesis of chiral biaryl natural products by asymmetric biaryl coupling

This tutorial review highlights the use of catalytic asymmetric 2-naphthol couplings in total synthesis. The types of chirality, chiral biaryl natural products, prior approaches to chiral biaryl natural products, and other catalytic asymmetric biaryl couplings are outlined. The three main categories of chiral catalysts for 2-naphthol coupling (Cu, V, Fe) are described with discussion of their limitations and advantages. Applications of the copper catalyzed couplings in biomimetic syntheses are discussed including nigerone, hypocrellin, calphostin D, phleichrome, and cercosporin.
Intergranular Crack‐Deflection Toughening in Silicon Carbide

The fracture toughness of three SiC-based materials was examined and correlated to toughening mechanisms. Crack deflection along grain boundaries in hot-pressed SiC-Al_2O_3 and SiC-ZrO_2 provided notable toughness increases compared to sintered α-Sic, which fractures transgranularly. The existence of a crack-deflection mechanism was confirmed by scanning electron microscopy.
Vapor‐liquid phase behavior of the helium‐methane system

This report presents more extensive experimental vapor-liquid equilibria data for the helium methane system than are found in the literature. A static sampling technique was used to obtain vapor and liquid compositions for six temperatures between −180° and −85°C. and pressures up to 2,000 lb./sq.in.abs. Data at 2,000 lb./sq.in.abs. were extended to the critical temperature of the mixture. Average scatter of the data from the smoothed lines is approximately 1% of the helium concentration or 0.03 mole % helium, whichever is larger. Vapor compositions at −140°, −160°, and −180°C. were analyzed by a different technique and scattered on the average from the smoothed curve less than 4% of the methane concentration. Comparisons are drawn between the data of this study and the previously published work of Kharakhorin. The solubility of helium in liquid methane was found to be considerably less than the values indicated by Kharakhorin. Experimental data are presented in tabular form and in various phase composition diagrams. The behavior of the helium-methane system is seen to be very similar to that of the helium-nitrogen system, with helium being much less soluble in methane than in nitrogen. The data were satisfactorily represented by means of the Krichevsky-Kazarnovsky equation. Extrapolations to higher pressures should be feasible.
Lossy radial diffusion of relativistic Jovian electrons

The radial diffusion equation with synchrotron losses is solved by the Laplace-transform method for near equatorially mirroring relativistic electrons. The evolution of a power-law distribution function is found, and the characteristics of synchrotron burnoff are stated in terms of explicit parameters for an arbitrary diffusion coefficient of a specific form. The peaking of the 10.4-cm volume emissivity from Jupiter at an L shell of about 1.8 provides an estimate of the diffusion coefficient in the radiation belts; one value is suggested as the appropriate modification, for an equatorial field strength of 4.2 G, of the Birmingham et al. (1974) result. Nonsynchrotron losses are included phenomenologically; from the phase-space densities reported by McIlwain and Fillius (1975), the particle lifetime is estimated. Asymptotic forms for the distribution in the strong synchrotron loss regime are provided.
Low temperature terahertz spectroscopy of n-InSb through a magnetic field driven metal-insulator transition

The authors use fiber-coupled photoconductive emitters and detectors to perform terahertz spectroscopy of lightly doped n-InSb directly in the cryogenic (1.5K) bore of a high-field superconducting magnet. They measure transmission spectra from 0.1to1.1THz as the sample is driven through a metal-to-insulator transition (MIT) by applied magnetic field. In the low-field metallic state, the data directly reveal the plasma edge and magnetoplasmon modes. With increasing field, a surprisingly broad band (0.3–0.8THz) of low transmission appears at the onset of the MIT. This band subsequently collapses and evolves into the sharp 1s→2p− transition of electrons “frozen” onto isolated donors in the insulating state.
Arudonine, an allelopathic steroidal glycoalkaloid from the root bark of Solanum arundo Mattei.

Abstract Bioassay-guided fractionation of the methanol extract of the root bark of Solanum arundo Mattei led to the isolation of a steroidal glycoalkaloid, designated arudonine, which was elucidated to be solasodine O -α- l -rhamnopyranosyl-(1 → 2)-{[β- d -xylopyranosyl-(1 → 3)], [α- l -rhamnopyranosyl-(1 → 4)]-β- d -glucopyranoside. This steroidal glycoalkaloid inhibited the growth of lettuce seedlings ( Lactuca sativa ).
KH 15D: Gradual Occultation of a Pre-Main-Sequence Binary

We propose that the extraordinary "winking star" KH 15D is an eccentric pre-main-sequence binary that is gradually being occulted by an opaque screen. This model accounts for the periodicity, depth, duration, and rate of growth of the modern eclipses; the historical light curve from photographic plates; and the existing radial velocity measurements. It also explains the rebrightening events that were previously observed during eclipses and the subsequent disappearance of these events. We predict the future evolution of the system and its full radial velocity curve. Given the small velocity of the occulting screen relative to the center of mass of the binary, the screen is probably associated with the binary and may be the edge of a precessing circumbinary disk.
Iridium-Catalyzed Regioselective and Enantioselective Allylation of Trimethylsiloxyfuran

We report the regio- and enantioselective allylation of an ester enolate, trimethylsiloxyfuran. This enolate reacts at the 3-position with linear aromatic allylic carbonates or aliphatic allylic benzoates to form the branched substitution products in the presence of a metallacyclic iridium catalyst. This process provides access to synthetically important 3-substituted butenolides in enantioenriched form. Stoichiometric reactions of the allyliridium intermediate suggest that the trimethylsiloxyfuran is activated by the carboxylate leaving group.
Selecting a requirement determination methodology-contingency approach revisited

Abstract Previous research proposed a contingency approach to selecting a particular requirement determination methodology because of the uncertainty that exists in defining application/ organizational information requirements. Recent research has shown that organizations use information to reduce uncertainty, to resolve equivocality, or both. Since the nature of information used to reduce uncertainty is different from that used to resolve equivocality, it is necessary to decide which is needed before starting to design the future system. This paper presents a three step approach to selecting a requirement determination methodology. The first step calls for assessment of the degree of uncertainty and equivocality present in the application. Based on this, an appropriate information acquisition strategy is identified. The third step calls for the selection of RD methodologies that are effective in acquiring the needed information. This approach is illustrated with a set of examples.
The origin of baryons in the Universe

THERE are several clues to the history of the early Universe. The 3-K microwave background indicates that the Universe was highly isotropic when it was about a half million years old, and the abundance of 4He (also D, 3He and 7Li) indicates that nucleosynthesis was taking place when the Universe was about three minutes old. These two facts are strong evidence that the Universe began from a hot big bang1. In addition, Hawking, Ellis and Penrose have proved (within general relativity) that the existence of the 3-K radiation implies the Universe must have been singular in its past2,3. The existence and clustering of galaxies indicate there were some deviations from homogeneity in the early Universe. Perhaps the most curious fact about the Universe is that it is composed almost entirely of matter (the Universe contains negligible amounts of antimatter) and that the number of baryons per photon (∼baryon/entropy ratio) is between 10−10 and 10−8 (ref. 4). If baryon number is absolutely conserved, then it follows that the baryon number of the Universe must be viewed merely as an initial condition. Recent ideas in particle physics when applied to the early Universe may explain how an initially baryon-symmetrical (zero net baryon number) Universe could have evolved into one with net baryon number. Here, we will discuss these ideas and other interesting astrophysical implications.
Upper bounds on sets of orthogonal colorings of graphs

Abstract We generalize the notion of orthogonal latin squares to colorings of simple graphs. Two n -colorings of a graph are said to be orthogonal if whenever two vertices share a color in one coloring they have distinct colors in the other coloring. We show that the usual bounds on the maximum size of a certain set of orthogonal latin structures such as latin squares, row latin squares, equi- n squares, single diagonal latin squares, double diagonal latin squares, or sudoku squares are special cases of bounds on orthogonal colorings of graphs.
Political representation of China–Africa: the tale of a playful panda, or a threatening dragon?

How is Western media portraying China–Africa relations, and what consequences do they have on Chinese media reactions and portrayals of China–Africa relations? This article takes an innovative approach analysing The Economist's rhetoric and China Daily Africa Weekly's political cartoons in order to ascertain the political representation of China–Africa relations in each of these outlets. The findings show that although there are major differences between the two sources in terms of the rhetoric used, in the metaphors, as well as cartoons used for illustrations, there is nonetheless an important similarity in the paternalistic tone present in both types of reporting. That is to say, there is a lack of African agency in the narratives displayed in these articles and cartoons analysed. The article closes by presenting some reflections and suggestions as to what can be done to improve Chinese media's reporting on China–Africa.
Epidemiology of Bloodstream Infections in Burn-Injured Patients: A Review of the National Burn Repository

Bloodstream infections (BSIs) are a major cause of morbidity and mortality in thermally injured patients. However, these infections have not been well defined in this patient population. Therefore, the authors performed a retrospective case-control study to characterize the epidemiology, microbiology, and outcomes of burn-associated BSIs. A retrospective review of all patients in the National Burn Repository (NBR) between the years 1981 and 2007 was performed. All cases that had infection listed under complications were included in this study. For each case, two randomly selected patients from the same time period served as controls. Patient demographic data, extent of %TBSA, and type of infection were extracted. Primary end point was mortality. Secondary endpoints were hospital length of stay (LOS), intensive care unit LOS, total ventilator days, and hospital charges. Further analysis of the data involved case-matching patients by TBSA deciles, adjustment for the effects of TBSA and other potential confounders, and a sensitivity analysis of the effects of including or excluding sites that might have failed to consistently capture BSI information. A total of 11,793 patients (3931 cases and 7862 control) were included in the study. Of cultures revealing a Gram-positive organism, Staphylococcus aureus (32%) was the most common. From samples where isolation of a Gram-negative species occurred, Pseudomonas aeruginosa (35%) was more prominent. Infected patients were older (40.9 vs 32.8, P < .05) and had higher %TBSA (22.2 vs 7.9, P < .05). BSI was associated with significantly higher mortality (21.9% vs 3.09%), hospital LOS (47.4 vs 8.8 days) intensive care unit LOS (30.8 vs 2.6 days), ventilator days (29.2 vs 1.4 days), and hospital charge ($339,909.91 vs $33,272.43); P < .001 for all values. On evaluation of case-matched controls, mortality was higher for patients with BSI only <50% TBSA strata. Conclusions were unaffected by adjustment for TBSA and other possible confounders and was not influenced by possible failure of some sites to consistently capture BSI information. Development of BSI in hospitalized burn patients is associated with significant increases in morbidity, mortality, and resource utilization.
Testing for Fraud in the Residential Mortgage Market: How Much Did Early-Payment-Defaults Overpay for Housing?

Current explanations for the high rate of default and foreclosure in the U.S. emphasize house price fluctuations and lax lending criteria. Another explanation for default and foreclosure, which has generally been neglected in the academic literature but not by the FBI, is fraud. One impediment to identifying and measuring fraud is the lack of statistical tests capable of detecting it. This paper proposes a simple method to detect transactions where fraud may have occurred. The models proposed here are important for at least three reasons. First they can document the role of fraud in the mortgage foreclosure crisis. Second, they can serve as part of a forensic effort designed to detect and deter mortgage fraud. Third, they demonstrate that mortgage fraud distorts house price indexes because it artificially elevates house prices during the period of fraud followed by a subsequent collapse due to the foreclosure sales. Accordingly, fraud can give the false impression that foreclosure lowers area house prices when it actually artificially inflates them. This suggests an alternative interpretation for the recent empirical literature on externalities from foreclosure.
Brightness limitations in multi-kiloampere electron beam sources☆

Heuristic relationships such as the Lawson-Penner criterion, used to scale free electron laser (FEL) amplifier gain and efficiency over orders of magnitude in beam current and brightness, have no fundamental basis. The brightness of a given source is set by practical design choices such as peak voltage, cathode type, gun electrode geometry, and focusing field topology. The design of low emittance, high current electron guns has received considerable attention at Livermore over the past few years. The measured brightnesses of the experimental test accelerator (ETA) and advanced test accelerator (ATA) guns are less than predicted with the EBQ [1] gun design code; this discrepancy is due to plasma effects from the present cold, plasma cathode in the code. The EBQ code is well suited to exploring the current limits of gridless relativistic Pierce columns with moderate current density (< 50 A/cm2) at the cathode. As EBQ uses a steady-state calculation it is not amenable for study of transient phenomena at the beam head. For this purpose, a Darwin approximation code, DPC, has been written. The main component in our experimental cathode development effort is a readily modified electron gun that will allow us to test many candidate cathode materials, types and electrode geometries at field stresses up to 1 MV/cm.
Function of ventricular pacemakers during resuscitation.

The reciprocal effects of resuscitation and permanent, ventricular-inhibited pacemakers were examined in four, well-documented cases of witnessed out-of-hospital arrest. The resulting observations provide useful insight in the treatment of cardiac arrest in the large number of patients with permanent pacemakers. Transient sensing malfunctions occurred in the two patients in whom direct current countershocks were not required and were probabaly related to the severely deranged state of the myocardium. In spite of periods of asynchronous pacing in this critically unstable setting, no arrhythmias were precipitated. In the two patients who required defibrillation, transient malfunctions of pacing, capture and sensing occurred in spite of protective electronics in the pacing system, the left-sided location of the generator and, in one patient, the bipolar configuration. The pacemaker appeared to intermittently sense coarse ventricular fibrillatory waves. The malfunctions in the two latter cases were probably the result of the combined effects of the countershock and the abnormal state of the myocardium. All four patients succumbed, three in the emergency room and one on the eighth hospital day. Outcome was predominantly determined by the patient's response to therapeutic interventions. The observed pacemaker malfunctions, although potentially life-threatening, had no obvious, adverse effect on outcome in these four cases, mainly because of the transient nature of the abnormalities. Indeed, in one case, the presence of pacemaker activity was pivotal in identifying the native rhythm, illustrating the diagnostic potential of this analytical approach.