bluuebunny/crossref_metadata_2025 huggingface dataset:
Planetary cratering 1. The question of multiple impactor populations: Lunar evidence
Authors: Hartmann William K.
Published: June 2012

Abstract— This paper addresses several current issues related to use of craters in interpreting planetary surface histories. The primary goal is to test the widely adopted hypothesis of multiple populations of impactors at different times or places in the Solar System.

New data presented here revise a “lunar highland” crater diameter distribution that has been widely used as evidence of an early distinct population of impactors. This curve, which has a depression of the size distribution at mid‐sizes, does not, in fact, represent the lunar highlands generally. I show that it is associated with regions of intercrater plains. The more extensive the obliteration by intercrater plains, the deeper the depression. Modeling indicates that the depression of the curve is caused by the obliteration process itself. The oldest, most cratered regions of lunar highlands do not show the depression.

These findings call into question earlier interpretations of multiple populations of impactors in the Solar System and of a distinctive primordial population.

The present work is consistent, instead, with (1) a relatively uniform size distribution of interplanetary impactors, of mixed origins, back to 4 Ga ago and throughout the sampled Solar System; (2) fragmentation as the process that produced that size distribution; (3) saturation equilibrium on the most heavily cratered surfaces; and (4) differences in structure in the size distribution caused not by distinct impactor populations but by episodes of endogenic obliteration.

If accepted, these results would modify some studies of solar system evolution, including assertions of two to five distinct populations of impactors, assumptions of lack of saturation equilibrium, and identifications of specific heliocentric or planetocentric sources for impactors within outer planet satellite systems.
Chemical studies of H chondrites — 7. Contents of Fe3+ and labile trace elements in Antarctic samples
Authors: Wolf Stephen F. , Lipschutz Michael E.
Published: June 2012

Abstract— Linear discriminant analysis and logistic regression have been applied to concentration data for 10 labile trace elements (Rb, Ag, Se, Cs, Te, Zn, Cd, Bi, Tl and In) in 33 Antarctic H4–6 chondrites. The proportion of bulk Fe in the Fe3+ state, Fe3+/Fe, of these same chondrites permit their assignment to less‐ and more‐weathered suites. Wherever the division between these suites is placed, the results are identical and consistent with the null hypothesis that the suites sample a single preterrestrial compositional population. Hence, no evidence exists that preterrestrial contents of labile trace elements in Antarctic H4–6 chondrites have been significantly altered by weathering as quantified by Fe3+/Fe or the A‐B‐C weathering index.
The Fayette County, Texas, meteorites
Authors: McCoy Timothy J. , Ehlmann Arthur J. , Keil Klaus
Published: June 2012

Abstract— We report the first petrologic examination of all stone meteorites of Fayette County, Texas. The 10 stones represent four or five different fall events. The three recovered Bluff stones represent two falls. Bluff (a), which includes the 145.5‐kg Bluff #1 stone, is classified as L5(S4), whereas Bluff (b) is classified as L4(S3) and is represented by a single stone. The studied Cedar stones are classified as H4(S3), and all four Cedar stones appear to define a strewnfield. Round Top (a), classified as L5(S3) and represented by two stones, is unrelated to either Bluff or Cedar. Round Top (b) [H4(S3); 1 stone], whose exact provenance is unknown, might be a transported fragment of the Cedar shower.
Mineralogy of a refractory inclusion in the Allende (C3V) meteorite
Authors: Steele Ian M.
Published: June 2012

Abstract— A spherical, 220‐μm diameter, spinel‐hibonite‐perovskite inclusion from the Allende C3V meteorite contains a central hibonite cluster with an angular boundary. This central hibonite is enclosed within spinel that is zoned from Mg‐rich at the hibonite boundary to more Fe‐rich at the inclusion boundary. This spinel zone includes lath‐shaped hibonites usually oriented subradial to the central hibonites. Two textural types of perovskites are present as exsolution from the central hibonite and as equidimensional grains within both the central hibonite and spinel. These second perovskites have exsolution lamellae of Al2O3. Within the central hibonite and adjacent to some equidimensional perovskites, a fine porous phase interpreted as alteration has a composition of nearly pure Al2O3 with minor amounts of Na and Si. This is possibly either an intergrowth of corundum and nepheline or a modified Al2O3, β‐alumina.

The central hibonites and equidimensional perovskites are considered relict grains on which the spinel‐hibonite layer crystallized. The relict material had undergone slow cooling in a previous event to produce exsolution of original high‐temperature compositions. Later alteration caused breakdown of hibonite to give an Al2O3‐rich phase. This inclusion represents a composite body which formed in a Ca‐Al‐rich environment.
Coolidge and Loongana 001: A new carbonaceous chondrite grouplet
Authors: Kallemeyn Gregory W. , Rubin Alan E.
Published: June 2012

Abstract— Petrographic and bulk compositional data suggest the existence of a new grouplet of carbonaceous chondrites consisting of Coolidge and Loongana 001. Coolidge is a carbonaceous chondrite find from Kansas, USA, previously considered a metamorphosed CV chondrite. Loongana 001 is a recent find from Western Australia. It has a high matrix/chondrule modal abundance ratio, 1–2 vol% refractory inclusions and high refractory lithophile abundance ratios (∼1.35x CI), indicating that it is a carbonaceous chondrite.

Coolidge and Loongana 001 have many compositional and petrographic similarities. They have refractory element abundances in the range of CV chondrites, significantly higher than those in the CR chondrites. They have similar volatile element abundance patterns showing low volatile element abundances relative to both CR and CV chondrites. Coolidge and Loongana 001 have similar chondrule dimensions and shapes, oxidation states and opaque mineral assemblages. They are also similar in petrologic type (3.8–4) and shock stage (S2).

Although both Coolidge and Loongana 001 may be related to the CV clan, they are not CV chondrites, nor are they formed by metamorphism of a CV precursor. They are distinctly different in composition from CV chondrites and their chondrules are smaller and have a much lower abundance of coarse‐grained chondrule rims. Coolidge and Loongana 001 constitute a distinct carbonaceous chondrite grouplet.
Post‐entry and volcanic contaminant abundances of zinc, copper, selenium, germanium and gallium in stratospheric micrometeorites
Authors: Rietmeijer Frans J. M.
Published: June 2012

Abstract— Some fraction of Zn, Cu, Se, Ga and Ge in chondritic interplanetary dust particles (IDPs) collected in the lower stratosphere between 1981 May and 1984 June has a volcanic origin. I present a method to evaluate the extent of this unavoidable type of stratospheric contamination for individual particles. The mass‐normalised abundances for Cu and Ge as a function of mass‐normalised stratospheric residence time show their time‐integrated stratospheric aerosol abundances. The Zn, Se and Ga abundances show a subdivision into two groups that span approximately two‐year periods following the eruptions of the Mount St. Helens (1980 May) and El Chichón (1982 April) volcanos. Elemental abundances in particles collected at the end of each two‐year period indicate low, but not necessarily ambient, volcanic stratospheric abundances. Using this time‐integrated baseline, I calculate the stratospheric contaminant fractions in nine IDPs and show that Zn, Se and Ga abundances in chondritic IDPs derive in part from stratospheric aerosol contaminants. Post‐entry elemental abundances (i.e., the amount that survived atmospheric entry heating of the IDP) show enrichments relative to the CI abundances but in a smaller number of particles than previously suggested.
Axtell, a new CV3 chondrite find from Texas
Authors: Simon S. B. , Grossman L. , Casanova I. , Symes S. , Benoit P. , Sears D. W. G. , Wacker J. F.
Published: June 2012

Abstract— We describe a previously unreported meteorite found in Axtell, Texas, in 1943. Based on the mineralogical composition and texture of its matrix and the sizes and abundance of chondrules, we classify it as a CV3 carbonaceous chondrite. The dominant opaque phase in the chondrules is magnetite, and that in refractory inclusions is Ni‐rich NiFe metal (awaruite). Axtell, therefore, belongs to the oxidized subgroup of CV3 chondrites, although unlike Allende it escaped strong sulfidation. The meteorite bears a strong textural resemblance to Allende, and its chondrule population and matrix appear to be quite similar to those of Allende, but its refractory inclusions, thermoluminescence properties, and cosmogenic 60Co abundances are not. Our data are consistent with a terrestrial age for Axtell of ∼100 years and a metamorphic grade slightly lower than that of Allende.
Report of centimeter‐sized tektites in Pima County, Arizona, cannot be verified
Authors: Kring David A. , Hildebrand Alan R. , Drake Michael J. , Melosh H. Jay , Vickery Ann M.
Published: June 2012

Abstract— Glassy objects reportedly found in Pima County, Arizona, have been identified as tektites. A field survey of the area where they were said to occur, however, did not produce any other tektites, nor did it reveal any other geologic features that might indicate a nearby impact crater. The major‐, minor‐, and trace‐element composition of one specimen is similar to those measured in indochinites, which suggests the objects reportedly from Pima County were instead transported to southern Arizona from Indochina by people.
Factors influencing response to Botulinum toxin type A in patients with idiopathic cervical dystonia: results from an international observational study
Authors: Misra Vijay P , Ehler Edvard , Zakine Benjamin , Maisonobe Pascal , Simonetta-Moreau Marion ,   on behalf of the INTEREST IN CD group
Published: June 2012

Objectives

Real-life data on response to Botulinum toxin A (BoNT-A) in cervical dystonia (CD) are sparse. An expert group of neurologists was convened with the overall aim of developing a definition of treatment response, which could be applied in a non-interventional study of BoNT-A-treated subjects with CD.

Design

International, multicentre, prospective, observational study of a single injection cycle of BoNT-A as part of normal clinical practice.

Setting

38 centres across Australia, Belgium, Czech Republic, France, Germany, The Netherlands, Portugal, Russia and the UK.

Participants

404 adult subjects with idiopathic CD. Most subjects were women, aged 41–60 years and had previously received BoNT-A.

Outcome measures

Patients were classified as responders if they met all the following four criteria: magnitude of effect (≥25% improvement Toronto Western Spasmodic Torticollis Rating Scale), duration of effect (≥12-week interval between the BoNT-A injection day and subject-reported waning of treatment effect), tolerability (absence of severe related adverse event) and subject's positive Clinical Global Improvement (CGI).

Results

High rates of response were observed for magnitude of effect (73.6%), tolerability (97.5%) and subject's clinical global improvement (69.8%). The subjective duration of effect criterion was achieved by 49.3% of subjects; 28.6% of subjects achieved the responder definition. Factors most strongly associated with response were age (<40 years; OR 3.9, p<0.05) and absence of baseline head tremor (OR 1.5; not significant).

Conclusions

Three of four criteria were met by most patients. The proposed multidimensional definition of response appears to be practical for routine practice. Unrealistically high patient expectation and subjectivity may influence the perception of a quick waning of effect, but highlights that this aspect may be a hurdle to response in some patients.

Clinical registration number

(NCT00833196;ClinicalTrials.gov).
HYPERSURFACES IN NONCOMPACT COMPLEX GRASSMANNIANS OF RANK TWO
Authors: BERNDT JÜRGEN , SUH YOUNG JIN
Published: June 2012

Consider a Riemannian manifold N equipped with an additional geometric structure, such as a Kähler structure or a quaternionic Kähler structure, and a hypersurface M in N. The geometric structure induces a decomposition of the tangent bundle TM of M into subbundles. A natural problem is to classify all hypersurfaces in N for which the second fundamental form of M preserves these subbundles. This problem is reasonably well understood for Riemannian symmetric spaces of rank one, but not for higher rank symmetric spaces. A general treatment of this problem for higher rank symmetric spaces is out of reach at present, and therefore it is desirable to understand this problem better in a few special cases. Due to some conceptual differences between symmetric spaces of compact type and of noncompact type it appears that one needs to consider these two cases separately. In this paper we investigate this problem for the rank two symmetric space SU 2, m/S(U2Um) of noncompact type.
ENHANCED TRANSMITTANCE AND RESOLUTION OF PHOTONIC CRYSTAL FLAT LENS BY SURFACE-EDGE ENGINEERING
Authors: GUO HAO , WANG CANCAN , ZHANG PEIYUAN , CHEN HONGJUN , LI YUN , WU LISHU , ZHANG XIONG , CUI YIPING
Published: June 2012

We proposed a novel two-dimensional (2D) photonic crystal (PC) flat lens based on the surface-edge engineering of a PC slab, operating as an n = -1 superlens at λ = 1.55 μm. The cross-section at the truncated edge of the flat lens is similar to an "anti-reflection grating", which is employed to reduce the reflectivity of propagative waves. The PC flat lens with a low reflectance of 1% was realized by the proposed truncated surface-edge for an InP / InGaAsP / InP 2D PC slab. The simulation results obtained with finite-difference time-domain (FDTD) method show that a PC flat super lens with a far-field resolution of 0.41 λ and a high transmittance of 81.9% can be achieved by the engineering of the truncated surface-edge at hetero-interface.
POSSIBLE Si-BASED HALF-METALLIC MATERIALS: MnSi46 CLATHRATES
Authors: ZHAO ZHI-WEI , WANG JING , ZHAO HUI-YAN , LIU YING
Published: June 2012

The structural and magnetic properties of M Si 46 (M = Mn , Fe , Co and Ni ) clathrates have been studied using density functional theory calculations within the generalized gradient approximation. When the structures involve a dopant at the center of a Si 20 or Si 24 cage, the results show that the neighboring atoms around the dopant are drawn in toward the center. Some of the silicon clathrates with a Mn or Co dopant at the center site of a Si 20 cage, or a Mn , Fe or Ni dopant at the center site of a Si 24 cage are found to be half-metallic materials with large magnetic moments, and others with a Fe or Ni dopant at the center site of a Si 20 cage or a Co dopant at the center site of a Si 24 cage display semi-metallic characters. In particular, MnSi 46 with a half-metallic gap of 0.70 eV and a magnetic moment of 5.00 μ B shows promise for applications in the field of spintronics.
EMERGING COHESION AND INDIVIDUALIZATION IN COLLECTIVE ACTION: A CO-EVOLUTIVE APPROACH
Authors: LOZANO SERGI , BORGE-HOLTHOEFER JAVIER , ARENAS ALEX
Published: June 2012

By means of a simple computational model, we explore a dynamic perspective of social cohesion in populations under stress. Dynamics are driven by the co-evolution of structural and cognitive dimensions. Submitted to sudden variations on its environmental conflict level, the model is able to reproduce certain characteristics previously observed in real populations in situations of emergency or crisis. A closer analysis of the results, observing both structural and cognitive together, uncovers a causal path from the level of conflict suffered by a population to variations on its social cohesiveness.
FACILITATED PHOTOLYSIS OF 9-FLUORENOL IN ALCOHOLS BY EXCITED-STATE HYDROGEN BOND REORGANIZATION
Authors: LIU YU-HUI , ZHOU PAN-WANG
Published: June 2012

Time-dependent density functional theory (TDDFT) and second-order coupled cluster method with resolution-of-the-identity approximation (RICC2) were used to investigate the photolysis dynamics of 9-fluorenol (FOH) in alcohols. In this work, a novel mechanism for the accelerated photolysis dynamics of FOH in alcohols is proposed for the first time. The two hydrogen bonds present different effects in the dissociation process of C9–O bond in MeOH⋯FOH⋯MeOH trimer: formation of hydrogen bond MeOH⋯FOH could weaken the C9–O bond, while, hydrogen bond FOH⋯MeOH fastens the bond. Moreover, the thermodynamic equilibrium can be accomplished in both ground and excited states between hydrogen-bonded complexes, since the hydrogen bond reorganization occurs in hundreds of femtosecond upon the excitation. The excited-state potential energy (PE) curves along C9–O bond have been optimized in S1state. The cleavage of C9–O bond upon the photoexcitation would be facilitated effectively in MeOH⋯FOH dimer. This leads the thermodynamic equilibrium between hydrogen-bonded complexes leaning to the side of MeOH⋯FOH dimer to quench the fluorescence. Therefore, the photolysis of 9-fluorenol in alcohols can be facilitated effectively by MeOH⋯FOH hydrogen bond via excited-state hydrogen bond reorganization. Additionally, the excited-state hydrogen bond reorganization is also the rate-controlling step in photolysis of FOH in alcohols, since there is no barrier in the PE curve of MeOH⋯FOH dimer.
CHAMELEON GROUND STATE AND EXCITED STATES OF EDT-TTF-IM-F4TCNQ RADICAL DYAD IN DIFFERENT ENVIRONMENTS
Authors: ZHOU YUHUA , TAN KAI , LU XIN
Published: June 2012

We have performed a systematic density functional study on the ground-state electronic structure and excited states of a representative D-σ-A dyad, i.e. EDT-TTF-Im-F4TCNQ π-radical, in vacuo and in different conventional solvents (toluene, THF, DMF and DMSO) by using some popular hybrid density functionals (B3LYP, M05, M05-2X, PBE0 and BMK). It has been shown that the M05 and B3LYP functionals perform the best in predicting the intramolecular charge-transfer (ICT) pertaining to both the ground state and excited states of the dyad. The amphoteric dyad is liable to solvent-promoted ICT from its EDT-TTF-Im donor (D) to F4TCNQ acceptor (A), adopting a charge-unseparated ground state D-A• in vacuo, a partially zwitterionic ground state [D-A]• in nonpolar toluene solvent, and a fully zwitterionic ground state D•+-A- in such polar solvents as THF, DMF and DMSO. Owing to its solvent-dependent chameleon ground state, excited states of the dyad in solvents also exhibit remarkable dependence on solvent polarity, as revealed by TDDFT calculations. Furthermore, cluster model calculations revealed that intermolecular charge-transfer readily occurs between the dyads, accounting for the observed zwitterionic charge state in solid state and solid-state semiconductivity.
INVESTIGATION OF THE CONTRIBUTION FOR THE NONCOLLINEAR CHANNEL OF THE F(2P3/2,2P1/2) + H2/D2 REACTIONS ON FOUR DIABATIC POTENTIAL ENERGY SURFACES
Authors: XIE TING-XIAN
Published: June 2012

We performed the nonadiabatic time-dependent wave packet calculation on the four diabatic potential energy surfaces, which have the different barrier height, to investigate the contribution of the noncollinear channel for the F (2P) + H2/D2 (v = j = 0) reactions. The reaction probabilities, integral cross-sections, and rate constants are presented. The results indicate that the probabilities as the function of the collision energy have an obvious translation. The reactive activity of the reactions comes from the noncollinear reactive channel. The bent barrier height would decrease the reactive activity. The integral cross-sections are in the order of AWS < LWA-5 < LWA-78 ≈ MASW, which is opposite to that of the bent barrier height. At the lower temperature, the difference of the rate constants is unambiguous. As the temperature increases, the difference reduces. At the higher temperature, the rate constants computed on the four potential energy surfaces are close.
INSIGHTS INTO THE SOLVATO-/THERMO-PROMOTED INTRAMOLECULAR ELECTRON TRANSFER IN A TTF-σ-TCNQ DYAD WITH AN EXTREMELY LOW HOMO–LUMO GAP
Authors: ZHOU YUHUA , TAN KAI , LU XIN
Published: June 2012

The low-lying states of an organic donor-σ-acceptor dyad, i.e. tetrathiafulvalene-σ-tetracyano-p-quinodimethane (TTF-σ-TCNQ), in gas phase and in various solvents have been investigated by means of hybrid DFT calculations in combination with the conductor-like polarizable continuum model to describe solvent effects. It has been shown that the dyad, though preferring a closed-shell singlet ground state with an eclipsed conformation in gas phase, adopts the charge-separated zwitterionic states with an extended conformation (TTF+-σ-TCNQ-), i.e. open-shell singlet biradical ground state immediately followed by triplet biradical state, in polar solvent ( CH3CN and CH2Cl2 ) as a result of the intramolecular electron transfer (ET) stimulated by solvent polarization. The degree of such intramolecular ET is so strongly dependent on the polarity (dielectric constant) of solvent that the zwitterionic biradical states become more stable with respect to the closed-shell singlet state with increasing polarity of the solvent. As such, the dyad should show a higher ratio of biradicals in more polar solvent and/or at higher temperature and, hence, is chameleonic in nature.
A QUASI-CLASSICAL TRAJECTORY STUDY ON STEREODYNAMICS OF THEF+HCl(v = 0, j = 0) →HF+ClREACTION
Authors: YUE XIAN-FANG , FENG PEI
Published: June 2012

Quasiclassical trajectory (QCT) calculations for the title reaction are carried out by employing the recent developed accurate potential energy surface of the 12A′ ground state. Two angular distributions, P(θr) and P(ϕr), with θr, ϕrbeing the polar angles of the product angular momentum, and two commonly used polarization dependent differential cross sections, (2π/σ)(dσ00/dωt) and (2π/σ)(dσ20/dωt), with ωtbeing the polar coordinates of the product velocity, are generated in the center-of-mass frame. It was found that the product rotational angular momentum j′ is not only aligned, but also oriented along the negative direction of y-axis. We also investigated the product state distributions in the present work, and found that the vibrational and rotational state distributions are inverted. Influences of collision energies on the product polarization and state distributions are also shown and discussed.
SUITE OF TOOLS FOR STATISTICAL N-GRAM LANGUAGE MODELING FOR PATTERN MINING IN WHOLE GENOME SEQUENCES
Authors: GANAPATHIRAJU MADHAVI K. , MITCHELL ASIA D. , THAHIR MOHAMED , MOTWANI KAMIYA , ANANTHASUBRAMANIAN SESHAN
Published: June 2012

Genome sequences contain a number of patterns that have biomedical significance. Repetitive sequences of various kinds are a primary component of most of the genomic sequence patterns. We extended the suffix-array based Biological Language Modeling Toolkit to compute n-gram frequencies as well as n-gram language-model based perplexity in windows over the whole genome sequence to find biologically relevant patterns. We present the suite of tools and their application for analysis on whole human genome sequence.
SPIN TRANSPORT IN FRACTAL CONDUCTORS WITH THE RASHBA SPIN-ORBIT COUPLING
Authors: HO CHENG-YEN , CHANG CHING-RAY
Published: June 2012

Spatial behavior of spin transport in a Sierpinski gasket fractal subject to the Rashba spin-orbital coupling is studied from two dimensions to a quasi-one dimensional arrangement. We represent two normal metal leads by a self-energy matrix, discretize the derived continuous Hamiltonian in the tight-binding approximation, and apply the Landauer–Keldysh formalism to the nonequilibrium transport. It is observed that the spin Hall effect present in the resultant distribution of spin density critically depends on the fractal structure and the shape of the thin film. The local spin density and transmission are numerically computed for both fractal and nonfractal thin films varying from a two dimensional square lattice into a quasi-one dimensional fractal shape. Spin filter effect is observed from the asymmetrical geometrical shape of Sierpinski triangle and pure spin current can be derived at appropriate conditions.
Probabilistic modeling for job symbiosis scheduling on SMT processors
Authors: Eyerman Stijn , Eeckhout Lieven
Published: June 2012

Symbiotic job scheduling improves simultaneous multithreading (SMT) processor performance by coscheduling jobs that have “compatible” demands on the processor's shared resources. Existing approaches however require a sampling phase, evaluate a limited number of possible coschedules, use heuristics to gauge symbiosis, are rigid in their optimization target, and do not preserve system-level priorities/shares.

This article proposes probabilistic job symbiosis modeling, which predicts whether jobs will create positive or negative symbiosis when coscheduled without requiring the coschedule to be evaluated. The model, which uses per-thread cycle stacks computed through a previously proposed cycle accounting architecture, is simple enough to be used in system software. Probabilistic job symbiosis modeling provides six key innovations over prior work in symbiotic job scheduling: (i) it does not require a sampling phase, (ii) it readjusts the job coschedule continuously, (iii) it evaluates a large number of possible coschedules at very low overhead, (iv) it is not driven by heuristics, (v) it can optimize a performance target of interest (e.g., system throughput or job turnaround time), and (vi) it preserves system-level priorities/shares. These innovations make symbiotic job scheduling both practical and effective.

Our experimental evaluation, which assumes a realistic scenario in which jobs come and go, reports an average 16% (and up to 35%) reduction in job turnaround time compared to the previously proposed SOS (sample, optimize, symbios) approach for a two-thread SMT processor, and an average 19% (and up to 45%) reduction in job turnaround time for a four-thread SMT processor.
Integer affine transformations of parametric ℤ-polytopes and applications to loop nest optimization
Authors: Seghir Rachid , Loechner Vincent , Meister Benoît
Published: June 2012

The polyhedral model is a well-known compiler optimization framework for the analysis and transformation of affine loop nests. We present a new method to solve a difficult geometric operation that is raised by this model: the integer affine transformation of parametric ℤ-polytopes. The result of such a transformation is given by a worst-case exponential union of ℤ-polytopes. We also propose a polynomial algorithm (for fixed dimension), to count points in arbitrary unions of a fixed number of parametric ℤ-polytopes. We implemented these algorithms and compared them to other existing algorithms, for a set of applications to loop nest analysis and optimization.
TACOMA
Authors: Abbasi Zahra , Varsamopoulos Georgios , Gupta Sandeep K. S.
Published: June 2012

A two-tier Internet data center management scheme, TACOMA, with
thermal-aware server provisioning
(TASP) in one tier, and
thermal-aware workload distribution
(TAWD) in the other is proposed. TASP and TAWD coordinate to maximize the energy savings by leveraging the workload dynamics, at coarse and fine time scale, respectively. TACOMA is aware of the QoS constraints, the energy proportionality of servers, and the potential trade-off between cooling and computing power. The obtained energy savings are a combination of suspending idle servers, using servers at their peak efficiency, and avoiding heat recirculation.
Benefits of selective packet discard in networks-on-chip
Authors: Lankes Andreas , Wild Thomas , Wallentowitz Stefan , Herkersdorf Andreas
Published: June 2012

Today, Network on Chip concepts principally assume inherent lossless operation. Considering that future nanometer CMOS technologies will witness increased sensitivity to all forms of manufacturing and environmental variations (e.g., IR drop, soft errors due to radiation, transient temperature induced timing problems, device aging), efforts to cope with data corruption or packet loss will be unavoidable. Possible counter measures against packet loss are the extension of flits with ECC or the introduction of error detection with retransmission.

We propose to make use of the perceived deficiency of packet loss as a feature. By selectively discarding stuck packets in the NoC, a proven practice in computer networks, all types of deadlocks can be resolved. This is especially advantageous for solving the problem of message-dependent deadlocks, which otherwise leads to high costs either in terms of throughput or chip area. Strict ordering, the most popular approach to this problem, results in a significant buffer overhead and a more complex router architecture. In addition, we will show that eliminating local network congestions by selectively discarding individual packets also can improve the effective throughput of the network. The end-to-end retransmission mechanism required for the reliable communication, then also provides lossless communication for the cores.
On intellectual and instrumental values in science
Authors: Goldreich Oded
Published: June 2012

This opinionated essay discusses the role of intellectual and instrumental values in scientific fields, and the way these values evolve due to internal and external forces. It identifies two sources of the decline of intellectual values within a scientific field: (1) the direct intervention of outsiders in the dynamics of (successful) scientific fields, and (2) the decline of intellectual values in the society at large.
Automated model repair for distributed programs
Authors: Bonakdarpour Borzoo , Kulkarni Sandeep S.
Published: June 2012

Model repair is a formal method that aims at fixing bugs in models automatically. Typically, these models are finite state automata that can be compactly represented using guarded commands or variations thereof. The bugs in these models can be identified using traditional techniques, such as verification, testing, or runtime monitoring. However, these techniques do not assist in fixing bugs automatically. The goal in model repair is to automatically transform an input model into another model that satisfies additional properties (e.g., a property that the original model fails to satisfy). Moreover, such transformation should preserve the existing specification of the input model. In this article, we review the efforts in the past decade on developing model repair algorithms in different domains. These domains include distributed computing, fault-tolerance and self-stabilization, and real-time systems. We present the results on complexity analysis, techniques for tackling intractability of the problem and scalability, and related tools. The techniques and tools discussed in this article demonstrate the feasibility of automated synthesis of well-known protocols such as Byzantine agreement, token ring, fault-tolerant mutual exclusion, etc.
The effects of dobutamine and dopamine on intrapulmonary shunt and gas exchange in healthy humans
Authors: Bryan Tracey L. , van Diepen Sean , Bhutani Mohit , Shanks Miriam , Welsh Robert C. , Stickland Michael K.
Published: June 2012

The development of intrapulmonary shunts with increased cardiac output during exercise in healthy humans has been reported in several recent studies, but mechanisms governing their recruitment remain unclear. Dobutamine and dopamine are inotropes commonly used to augment cardiac output; however, both can increase venous admixture/shunt fraction (Qs/Qt). It is possible that, as with exercise, intrapulmonary shunts are recruited with increased cardiac output during dobutamine and/or dopamine infusion that may contribute to the observed increase in Qs/Qt. The purpose of this study was to examine how dobutamine and dopamine affect intrapulmonary shunt and gas exchange. Nine resting healthy subjects received serial infusions of dobutamine and dopamine at incremental doses under normoxic and hyperoxic (inspired O2fraction = 1.0) conditions. At each step, alveolar-to-arterial Po2difference (A-aDo2) and Qs/Qt were calculated from arterial blood gas samples, intrapulmonary shunt was evaluated using contrast echocardiography, and cardiac output was calculated by Doppler echocardiography. Both dobutamine and dopamine increased cardiac output and Qs/Qt. Intrapulmonary shunt developed in most subjects with both drugs and paralleled the increase in Qs/Qt. A-aDo2was unchanged due to a concurrent rise in mixed venous oxygen content. Hyperoxia consistently eliminated intrapulmonary shunt. These findings contribute to our present understanding of the mechanisms governing recruitment of these intrapulmonary shunts as well as their impact on gas exchange. In addition, given the deleterious effect on Qs/Qt and the risk of neurological complications with intrapulmonary shunts, these findings could have important implications for use of dobutamine and dopamine in the clinical setting.
Targeting the Insulin Growth Factor and the Vascular Endothelial Growth Factor Pathways in Ovarian Cancer
Authors: Shao Minghai , Hollar Stacy , Chambliss Daphne , Schmitt Jordan , Emerson Robert , Chelladurai Bhadrani , Perkins Susan , Ivan Mircea , Matei Daniela
Published: June 2012

Antiangiogenic therapy is emerging as a highly promising strategy for the treatment of ovarian cancer, but the clinical benefits are usually transitory. The purpose of this study was to identify and target alternative angiogenic pathways that are upregulated in ovarian xenografts during treatment with bevacizumab. For this, angiogenesis-focused gene expression arrays were used to measure gene expression levels in SKOV3 and A2780 serous ovarian xenografts treated with bevacizumab or control. Reverse transcription-PCR was used for results validation. The insulin growth factor 1 (IGF-1) was found upregulated in tumor and stromal cells in the two ovarian xenograft models treated with bevacizumab. Cixutumumab was used to block IGF-1 signaling in vivo. Dual anti-VEGF and IGF blockade with bevacizumab and cixutumumab resulted in increased inhibition of tumor growth. Immunohistochemistry measured multivessel density, Akt activation, and cell proliferation, whereas terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling (TUNEL) assay measured apoptosis in ovarian cancer xenografts. Bevacizumab and cixutumumab combination increased tumor cell apoptosis in vivo compared with therapy targeting either individual pathway. The combination blocked angiogenesis and cell proliferation but not more significantly than each antibody alone. In summary, IGF-1 activation represents an important mechanism of adaptive escape during anti-VEGF therapy in ovarian cancer. This study provides the rationale for designing bevacizumab-based combination regimens to enhance antitumor activity. Mol Cancer Ther; 11(7); 1576–86. ©2012 AACR.
Picture Agnosia as a Characteristic of Posterior Cortical Atrophy
Authors: Sugimoto Azusa , Midorikawa Akira , Koyama Shinichi , Futamura Akinori , Hieda Sotaro , Kawamura Mitsuru
Published: June 2012

Background: Posterior cortical atrophy (PCA) is a degenerative disease characterized by progressive visual agnosia with posterior cerebral atrophy. We examine the role of the picture naming test and make a number of suggestions with regard to diagnosing PCA as atypical dementia. Methods: We investigated 3 cases of early-stage PCA with 7 control cases of Alzheimer disease (AD). The patients and controls underwent a naming test with real objects and colored photographs of familiar objects. We then compared rates of correct answers. Results: Patients with early-stage PCA showed significant inability to recognize photographs compared to real objects (F = 196.284, p = 0.0000) as measured by analysis of variants. This difficulty was also significant to AD controls (F = 58.717, p = 0.0000). Conclusion: Picture agnosia is a characteristic symptom of early-stage PCA, and the picture naming test is useful for the diagnosis of PCA as atypical dementia at an early stage.
Periprocedural Bleeding and Thromboembolic Events With Dabigatran Compared With Warfarin
Authors: Healey Jeff S. , Eikelboom John , Douketis James , Wallentin Lars , Oldgren Jonas , Yang Sean , Themeles Ellison , Heidbuchel Hein , Avezum Alvaro , Reilly Paul , Connolly Stuart J. , Yusuf Salim , Ezekowitz Michael
Published: June 2012

Background—

Dabigatran reduces ischemic stroke in comparison with warfarin; however, given the lack of antidote, there is concern that it might increase bleeding when surgery or invasive procedures are required.

Methods and Results—

The current analysis was undertaken to compare the periprocedural bleeding risk of patients in the Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) trial treated with dabigatran and warfarin. Bleeding rates were evaluated from 7 days before until 30 days after invasive procedures, considering only the first procedure for each patient. A total of 4591 patients underwent at least 1 invasive procedure: 24.7% of patients received dabigatran 110 mg, 25.4% received dabigatran 150 mg, and 25.9% received warfarin,
P
=0.34. Procedures included: pacemaker/defibrillator insertion (10.3%), dental procedures (10.0%), diagnostic procedures (10.0%), cataract removal (9.3%), colonoscopy (8.6%), and joint replacement (6.2%). Among patients assigned to either dabigatran dose, the last dose of study drug was given 49 (35–85) hours before the procedure on comparison with 114 (87–144) hours in patients receiving warfarin,
P
<0.001. There was no significant difference in the rates of periprocedural major bleeding between patients receiving dabigatran 110 mg (3.8%) or dabigatran 150 mg (5.1%) or warfarin (4.6%); dabigatran 110 mg versus warfarin: relative risk, 0.83; 95% CI, 0.59 to 1.17;
P
=0.28; dabigatran 150 mg versus warfarin: relative risk, 1.09; 95% CI, 0.80 to 1.49;
P
=0.58. Among patients having urgent surgery, major bleeding occurred in 17.8% with dabigatran 110 mg, 17.7% with dabigatran 150 mg, and 21.6% with warfarin: dabigatran 110 mg; relative risk, 0.82; 95% CI, 0.48 to 1.41;
P
=0.47; dabigatran 150 mg: relative risk, 0.82; 95% CI, 0.50 to 1.35;
P
=0.44.

Conclusions—

Dabigatran and warfarin were associated with similar rates of periprocedural bleeding, including patients having urgent surgery. Dabigatran facilitated a shorter interruption of oral anticoagulation.

Clinical Trial Registration—

URL:
http://www.clinicaltrials.gov
. Unique identifier: NCT00262600.
The type III secretion system is necessary for the development of a pathogenic and endophytic interaction between Herbaspirillum rubrisubalbicans and Poaceae
Authors: Schmidt Maria Augusta , Balsanelli Eduardo , Faoro Hellison , Cruz Leonardo M , Wassem Roseli , de Baura Valter A , Weiss Vinícius , Yates Marshall G , Madeira Humberto M F , Pereira-Ferrari Lilian , Fungaro Maria H P , de Paula Francine M , Pereira Luiz F P , Vieira Luiz G E , Olivares Fábio L , Pedrosa Fábio O , de Souza Emanuel M , Monteiro Rose A
Published: June 2012

Background

Herbaspirillum rubrisubalbicans was first identified as a bacterial plant pathogen, causing the mottled stripe disease in sugarcane. H. rubrisubalbicans can also associate with various plants of economic interest in a non pathogenic manner.

Results

A 21 kb DNA region of the H. rubrisubalbicans genome contains a cluster of 26 hrp/hrc genes encoding for the type three secretion system (T3SS) proteins. To investigate the contribution of T3SS to the plant-bacterial interaction process we generated mutant strains of H. rubrisubalbicans M1 carrying a Tn5 insertion in both the hrcN and hrpE genes. H. rubrisulbalbicans hrpE and hrcN mutant strains of the T3SS system failed to cause the mottled stripe disease in the sugarcane susceptible variety B-4362. These mutant strains also did not produce lesions on Vigna unguiculata leaves. Oryza sativa and Zea mays colonization experiments showed that mutations in hrpE and hrcN genes reduced the capacity of H. rubrisulbalbicans to colonize these plants, suggesting that hrpE and hrcN genes are involved in the endophytic colonization.

Conclusions

Our results indicate that the T3SS of H. rubrisubalbicans is necessary for the development of the mottled stripe disease and endophytic colonization of rice.
Enhancement of musculocutaneous nerve reinnervation after vascular endothelial growth factor (VEGF) gene therapy
Authors: Haninec Pavel , Kaiser Radek , Bobek Vladimír , Dubový Petr
Published: June 2012

Background

Vascular endothelial growth factor (VEGF) is not only a potent angiogenic factor but it also promotes axonal outgrowth and proliferation of Schwann cells. The aim of the present study was to quantitatively assess reinnervation of musculocutaneous nerve (MCN) stumps using motor and primary sensory neurons after plasmid phVEGF transfection and end-to-end (ETE) or end-to-side (ETS) neurorrhaphy. The distal stump of rat transected MCN, was transfected with plasmid phVEGF, plasmid alone or treated with vehiculum and reinnervated following ETE or ETS neurorrhaphy for 2 months. The number of motor and dorsal root ganglia neurons reinnervating the MCN stump was estimated following their retrograde labeling with Fluoro-Ruby and Fluoro-Emerald. Reinnervation of the MCN stumps was assessed based on density, diameter and myelin sheath thickness of regenerated axons, grooming test and the wet weight index of the biceps brachii muscles.

Results

Immunohistochemical detection under the same conditions revealed increased VEGF in the Schwann cells of the MCN stumps transfected with the plasmid phVEGF, as opposed to control stumps transfected with only the plasmid or treated with vehiculum. The MCN stumps transfected with the plasmid phVEGF were reinnervated by moderately higher numbers of motor and sensory neurons after ETE neurorrhaphy compared with control stumps. However, morphometric quality of myelinated axons, grooming test and the wet weight index were significantly better in the MCN plasmid phVEGF transfected stumps. The ETS neurorrhaphy of the MCN plasmid phVEGF transfected stumps in comparison with control stumps resulted in significant elevation of motor and sensory neurons that reinnervated the MCN. Especially noteworthy was the increased numbers of neurons that sent out collateral sprouts into the MCN stumps. Similarly to ETE neurorrhaphy, phVEGF transfection resulted in significantly higher morphometric quality of myelinated axons, behavioral test and the wet weight index of the biceps brachii muscles.

Conclusion

Our results showed that plasmid phVEGF transfection of MCN stumps could induce an increase in VEGF protein in Schwann cells, which resulted in higher quality axon reinnervation after both ETE and ETS neurorrhaphy. This was also associated with a better wet weight biceps brachii muscle index and functional tests than in control rats.
Co-ordinate regulation of cytokinin gene family members during flag leaf and reproductive development in wheat
Authors: Song Jiancheng , Jiang Lijun , Jameson Paula Elizabeth
Published: June 2012

Background

As the global population continues to expand, increasing yield in bread wheat is of critical importance as 20% of the world’s food supply is sourced from this cereal. Several recent studies of the molecular basis of grain yield indicate that the cytokinins are a key factor in determining grain yield. In this study, cytokinin gene family members in bread wheat were isolated from four multigene families which regulate cytokinin synthesis and metabolism, the isopentenyl transferases (IPT), cytokinin oxidases (CKX), zeatin O-glucosyltransferases (ZOG), and β-glucosidases (GLU). As bread wheat is hexaploid, each gene family is also likely to be represented on the A, B and D genomes. By using a novel strategy of qRT-PCR with locus-specific primers shared among the three homoeologues of each family member, detailed expression profiles are provided of family members of these multigene families expressed during leaf, spike and seed development.

Results

The expression patterns of individual members of the IPT, CKX, ZOG, and GLU multigene families in wheat are shown to be tissue- and developmentally-specific. For instance, TaIPT2 and TaCKX1 were the most highly expressed family members during early seed development, with relative expression levels of up to 90- and 900-fold higher, respectively, than those in the lowest expressed samples. The expression of two cis-ZOG genes was sharply increased in older leaves, while an extremely high mRNA level of TaGLU1-1 was detected in young leaves.

Conclusions

Key genes with tissue- and developmentally-specific expression have been identified which would be prime targets for genetic manipulation towards yield improvement in bread wheat breeding programmes, utilising TILLING and MAS strategies.
Transforming growth factor-β suppresses metastasis in a subset of human colon carcinoma cells
Authors: Simms Neka A K , Rajput Ashwani , Sharratt Elizabeth A , Ongchin Melanie , Teggart Carol A , Wang Jing , Brattain Michael G
Published: June 2012

Background

TGFβ signaling has typically been associated with suppression of tumor initiation while the role it plays in metastasis is generally associated with progression of malignancy. However, we present evidence here for an anti-metastatic role of TGFβ signaling.

Methods

To test the importance of TGFβ signaling to cell survival and metastasis we compared human colon carcinoma cell lines that are either non-tumorigenic with TGFβ response (FET), or tumorigenic with TGFβ response (FETα) or tumorigenic with abrogated TGFβ response via introduction of dominant negative TGFβRII (FETα/DN) and their ability to metastasize. Metastatic competency was assessed by orthotopic transplantation. Metastatic colony formation was assessed histologically and by imaging.

Results

Abrogation of TGFβ signaling through introduction of a dominant negative TGFβ receptor II (TGFβRII) in non-metastatic FETα human colon cancer cells permits metastasis to distal organs, but importantly does not reduce invasive behavior at the primary site. Loss of TGFβ signaling in FETα-DN cells generated enhanced cell survival capabilities in response to cellular stress in vitro. We show that enhanced cellular survival is associated with increased AKT phosphorylation and cytoplasmic expression of inhibitor of apoptosis (IAP) family members (survivin and XIAP) that elicit a cytoprotective effect through inhibition of caspases in response to stress. To confirm that TGFβ signaling is a metastasis suppressor, we rescued TGFβ signaling in CBS metastatic colon cancer cells that had lost TGFβ receptor expression due to epigenetic repression. Restoration of TGFβ signaling resulted in the inhibition of metastatic colony formation in distal organs by these cells. These results indicate that TGFβ signaling has an important role in the suppression of metastatic potential in tumors that have already progressed to the stage of an invasive carcinoma.

Conclusions

The observations presented here indicate a metastasis suppressor role for TGFβ signaling in human colon cancer cells. This raises the concern that therapies targeting inhibition of TGFβ signaling may be imprudent in some patient populations with residual TGFβ tumor suppressor activity.