bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat-Stable Enterotoxin of EnterotoxigenicEscherichia colias a Vaccine Target
Authors: Taxt Arne , Aasland Rein , Sommerfelt Halvor , Nataro James , Puntervoll Pål
Published: March 2010

EnterotoxigenicEscherichia coli(ETEC) is responsible for 280 million to 400 million episodes of diarrhea and about 380,000 deaths annually. Epidemiological data suggest that ETEC strains which secrete heat-stable toxin (ST), alone or in combination with heat-labile toxin (LT), induce the most severe disease among children in developing countries. This makes ST an attractive target for inclusion in an ETEC vaccine. ST is released upon colonization of the small intestine and activates the guanylate cyclase C receptor, causing profuse diarrhea. To generate a successful toxoid, ST must be made immunogenic and nontoxic. Due to its small size, ST is nonimmunogenic in its natural form but becomes immunogenic when coupled to an appropriate large-molecular-weight carrier. This has been successfully achieved with several carriers, using either chemical conjugation or recombinant fusion techniques. Coupling of ST to a carrier may reduce toxicity, but further reduction by mutagenesis is desired to obtain a safe vaccine. More than 30 ST mutants with effects on toxicity have been reported. Some of these mutants, however, have lost the ability to elicit neutralizing immune responses to the native toxin. Due to the small size of ST, separating toxicity from antigenicity is a particular challenge that must be met. Another obstacle to vaccine development is possible cross-reactivity between anti-ST antibodies and the endogenous ligands guanylin and uroguanylin, caused by structural similarity to ST. Here we review the molecular and biological properties of ST and discuss strategies for developing an ETEC vaccine that incorporates immunogenic and nontoxic derivatives of the ST toxin.
Late Pleistocene proboscideans and early Fraser glacial sedimentation in eastern Fraser Lowland, British Columbia
Authors: Hicock Stephen R. , Hobson Keith , Armstrong John E.
Published: March 2010

Three recently radiocarbon-dated tusk segments from eastern Fraser Lowland indicate Pleistocene proboscideans (probably mammoths) lived there between 22 700 and 21 400 years ago during early Fraser (for the Fraser Lowland) ice advance into the area. Palynomorphs from silty sand adhering to a tusk indicate the animals grazed on open grassy floodplain. Sedimentologic and altimeter studies of tusk-bearing gravel indicate an early Fraser sandur, at least 10 km long and deposited at the same time as Coquitlam Drift, formed in Chilliwack Valley at the same time that a sandur or kame terrace was deposited against the north side of Promontory ridge. Probably about 21 000 years ago (the time of Coquitlam glacial maximum in western Fraser Lowland) ice blocked Chilliwack Valley, creating a glacial lake whose freshwater, Pediastrum-bearing, laminated silt has been observed up to 200 m asl. Stratigraphy and history of the area following deposition of the above gravels and silt are still uncertain without more chronologic control. However, proboscideans could have migrated southward and westward, away from ice advancing into Fraser Lowland, across ancestral Strait of Georgia via the Quadra sandur, and onto southeastern Vancouver Island to which earliest Fraser glacial ice probably advanced after 17 000 years BP.
Correlation of sea-level curves for the Lower Silurian of the Bruce Peninsula and Lake Timiskaming District (Ontario)
Authors: Colville Valerie R. , Johnson Markes E.
Published: March 2010

Paleobathymetric interpretation of strata from the Bruce Peninsula and Lake Timiskaming District of Ontario shows strong correlations with data from the Michigan Upper Peninsula and Ontario's Manitoulin Island. Three to four cycles of fluctuating sea level occurred during Early Silurian (Llandoverian) time throughout much of the northern Great Lakes area, and involved the highly regular replacement of ostracode–vermiform, coral–algal, and pentamerid communities by one another. Although exposure is more limited than on Manitoulin Island or the Michigan Upper Peninsula, important clues regarding Early Silurian geography are found in strata of the Bruce Peninsula and Lake Timiskaming District. Continued thinning of stratigraphic units and an increased incidence of disconformities from north to south on the Bruce Peninsula suggest the episodic rise of the Algonquin Arch farther to the south and west. Contrary to earlier paleogeographic reconstructions, the patterns of community changeovers preserved in the Silurian outlier of the Lake Timiskaming District indicate a persistent, open connection between the seas of the northern Great Lakes area and the Hudson Bay Lowlands. This interpretation is more in keeping with recent paleontologic work on faunal distributions.
The Brazeau Lake slide, Jasper National Park, Alberta
Authors: Cruden D. M.
Published: March 2010

An historic major rockslide has diverted John-John Creek northwards to its present channel flowing into Brazeau Lake in the Main Ranges of the Rockies in Jasper National Park, Alberta.The slide debris moved northeastwards from cliffs on the northeastern face of "Molard Mountain," an unnamed peak northeast of Flat Ridge in the Grand Brazeau. It reached the shores of Brazeau Lake.The debris occupies a plan area of 0.9 km2 with an average width of 500 m. An estimated average debris thickness of 5 m gives a volume of the displaced mass of 4.5 × 106 m3. The angle from the slide crown to the tip of the debris is about 18°. An approximate reconstruction of the depletion and accumulation of the slide suggests 23° as a lower bound for the angle of friction of the slide debris.The exposed rupture surface of the slide, a bedding plane in the lower portion of the Middle Cambrian Pika Formation, dips at 27° to the northeast. Dolostones, limestones, and shales from the Pika Formation form the slide debris. The slide site is in a panorama photographed in 1928. The slide shows on aerial photographs taken in 1951. A secondhand account of the slide places its occurrence in early July 1933. So the Brazeau Lake slide is the second major rockslide to occur in the Canadian Rockies this century and the first that is undoubtedly a natural event.
Sediment character and provenance in a complex fjord; Howe Sound, British Columbia
Authors: Syvitski James P. M. , Macdonald Robert D.
Published: March 2010

Howe Sound is a complex fjord in terms of geomorphology and circulation pattern. Sediment is presently being deposited in its deep basins from four distinct sources: (1) land-derived sediment from the Squamish River; (2) suspended sediment originating from surface waters influenced by discharges from the nearby Fraser River; (3) reworked Pleistocene lag deposits found on some shore platforms and sills throughout the sound; and (4) mine tailings from a defunct Cu–Zn mine. A less distinct source is sediment deposited via gravity flows from fjord wall slopes, including side-entry fanglomerate deltas, and the major Squamish River delta.Grain size data have been used to differentiate depositional versus nondepositional environments. In addition, surficial sediment samples collected from depositional basins could be modelled in terms of their size–frequency distribution and distance from source. Those that deviate from a predicted grain size distribution were found to be bimodal. Partitioning of their probability curves allows the establishment of mixing ratios of the major sediment sources, and indicates that the Squamish-derived sediment accounts for between 80 and 100% of recent Howe Sound deposition. Semi-quantitative XRD results can resolve the dispersion-directions of each source and show that: (a) mica can be used to trace the Squamish sediment source: (b) the chlorite pattern indicates the Fraser sediment source; and (c) quartz is useful in delineating pathways of sediment resuspended from lag deposits. These pathways are also substantiated by gradients in Cu, Ni, and Zn concentrations in the sediments.
Paleomagnetic reexamination of the Lower Ordovician Wabana and Bell Island Groups of the Avalon Peninsula of Newfoundland
Authors: Buchan K. L. , Hodych J. P.
Published: March 2010

The Wabana and Bell Island Groups of the Avalon Peninsula of Newfoundland contain oolitic hematite beds of Early Ordovician age, dipping ~11° north-northwest. Twenty-one oolitic hematite samples from nine sites were thermally demagnetized in 10 or 11 steps to 660 or 680 °C. At 450 °C, 15 samples from six sites define a stable magnetization direction (D = 21.2°, I = −12.5°, k = 137, α95 = 5.7°) with respect to bedding. The remaining six samples failed to attain the stable end-point, five of them because of growth of much "magnetite," which probably resulted from breakdown of siderite during thermal demagnetization.The paleopole for the Wabana – Bell Island Groups lies at 33°N 102°E (dm = 5.8°, dp = 3.0°). It is compared with other early Paleozoic paleopoles from cratonic North America and the Avalon zone, and its significance for the Iapetus Ocean is discussed.
First record of Labyrinthus soraufi Kobluk from the southern Appalachians: Lower Cambrian Shady Dolomite, Virginia
Authors: Kobluk David R.
Published: March 2010

Labyrinthus soraufi Kobluk 1979, previously known only from the upper Lower Cambrian Forteau Formation of southern Labrador, has been found within upper Lower Cambrian to lower Middle Cambrian Epiphyton mounds from the upper part of the Shady Dolomite in southwestern Virginia. This problematical fossil was a contributor to framework growth in both of its known occurrences. This find extends the geographic range of this fossil to include the southern Appalachians, and shows that L. soraufi is not a fossil unique to the Cambrian of Labrador but may possibly occur more widely through the North American Lower (and Middle?) Cambrian. The absence of archaeocyathids from the Epiphyton mounds in the Upper Shady Formation shows that L. soraufi was not restricted to archaeocyathid-bearing mounds or reefs.
Distribution, stratigraphy, petrochemistry, and palaeomagnetism of the late Pleistocene Old Crow tephra in Alaska and the Yukon
Authors: Westgate J. A. , Walter R. C. , Pearce G. W. , Gorton M. P.
Published: March 2010

The late Quaternary Old Crow tephra is a two-pyroxene, calc-alkaline dacite whose known areal extent is broadly delimited by a triangle with apices at the Seward Peninsula, the Wrangell Mountains, and the Old Crow Basin in the northern Yukon. Everywhere the tephra is fine grained (Mdσ = 5.33 ± 0.32) and moderately to poorly sorted (6σ = 1.33 ± 0.29). Samples from the extremities of the fall-out zone have similarity coefficients of 0.95.A palaeomagnetic excursion is recorded in sediments just below Old Crow tephra in the Fairbanks area and at Imuruk Lake on the Seward Peninsula. A short, full reversal of the magnetic field has been preserved at the corresponding stratigraphic level near Old Crow in the northern Yukon. Chronological controls based on 14C and fission-track dates and sedimentation rates show that these palaeomagnetic features are almost certainly partial records of the complex geomagnetic Blake Event, which occurred 100–120 ka ago.New petrochemical data demonstrate that the source of Old Crow tephra is in the eastern Aleutian arc.
Possible earthquake-induced soft-sediment faulting and remobilization in Pennsylvanian alluvial strata, southern New Brunswick, Canada
Authors: Plint A. G.
Published: March 2010

Braided river, sheetflood, and playa lake sediments of the Tynemouth Creek Formation (Lower Pennsylvanian) show superficial synsedimentary faulting and subsurface post-depositional sediment remobilization. A prominent palaeosol has been offset 90 cm on two faults, movement on which clearly preceded deposition of the overlying beds. Seventeen to 25 m below this horizon, large load structures, upward-branching siltstone intrusions, and three types of sandstone dike are recognised. Intrusion occurred on several occasions at different depths of burial and was the result of rapid, probably earthquake-induced dewatering. This interpretation is supported by the location of the study area, only a few kilometres to the north of the Cobequid–Chedabucto Fault, on which major strike-slip movement occurred during the Pennsylvanian.
Holocene glacial history of the Lituya District, southeast Alaska
Authors: Mann D. H. , Ugolini F. C.
Published: March 2010

Radiocarbon dates from the Lituya District of southeast Alaska indicate the occurrence of at least four glacial periods during the past 10 000 years. Further detail is added to the record by a relative-age chronology for moraines based on cross-cutting relationships, as well as soil, vegetation, and boulder weathering characteristics. The most recent deglaciation occurred approximately 350–500 years BP, ending advances begun shortly after 1500 years BP. The relative-age chronology for moraines indicates that at least three episodes of moraine building occurred during this period. Dates on logs in outwash and organic deposits in a moraine pond indicate glacial recession 1500–1900 years BP. This recession was preceded by advances beginning sometime after 3600 years BP and including several periods of moraine construction. Radiocarbon-dated basal organics in moraine ponds, buried soils, and overridden forest beds delimit a mid-Holocene advance ending before 5000 years BP and probably starting around 6000 years BP. Another advance probably occurred between 7400 and 9000 years BP; alternatively, it may have been earlier, but after 11 000 years BP. Regional comparisons are limited by the shortage of, and innate problems with, the glacial records, but do suggest that mid- and early Holocene advances were widespread in the southern Alaska region.
Multiphoton ionization of H2+ in the perturbative regime
Authors: Barmaki Samira , Laulan Stéphane
Published: March 2010

Multiphoton ionization of the H 2+ hydrogen molecular ion at fixed internuclear distance is investigated in the lowest order perturbation theory (LOPT). The parallel and perpendicular orientations between the polarization laser vector of the electric field and the H 2+ internuclear axis direction are considered. We calculate the generalized cross sections for the N = 2 to N = 6 photon ionization processes and we identify in each case the intermediate-state resonances. We show the efficiency of our method to describe resonance structures with high-energy resolution.
Discrete phase space - I: Variational formalism for classical relativistic wave fields
Authors: Das A.
Published: March 2010

This is the first in a series of papers dealing with a discrete phase space formulation for classical and quantum fields. This formulation leads to a representation of quantum field theory that is covariant and possesses singularity free S-matrix. In this paper, the classical relativistic wave equations are presented as partial difference equations in the arena of covariant discrete phase space. These equations are also expressed as difference-differential equations in discrete phase space and continuous time. The relativistic invariance and covariance of the equations in both versions are established. The partial difference and difference-differential equations are derived as the Euler–Lagrange equations from the variational principle. The difference and difference-differential conservation equations are derived. Finally, the total momentum, energy, and charge of the relativistic classical fields satisfying difference-differential equations are computed.
Theoretical investigations on the spin Hamiltonian parameters and the local structure for Rh2+ in rutile
Authors: Zhang S. X. , Wu S. Y. , Xu P. , Li L. L.
Published: March 2010

The spin Hamiltonian parameters, the g factors gi (i = x, y, z) and the hyperfine structure constants Ai, and the local structure for Rh2+ in rutile (TiO2) are theoretically investigated from the perturbation formulas of these parameters for a 4d7 ion under rhombically elongated octahedra. In view of the covalency, the ligand orbital and spin-orbit coupling contributions are taken into account from the cluster approach. The planar bond angle in the impurity center is found to be 7.5° larger than that of the host Ti4+ site because of the Jahn–Teller effect via bending of the planar Rh2+-O2– bonds, leading to much smaller rhombic distortion. The theoretical spin Hamiltonian parameters based on the above Jahn–Teller angular distortion show reasonable agreement with the experimental data.
Dispersive shock waves propagating in the cubic-quintic derivative nonlinear Schrödinger equation
Authors: Kengne E. , Lakhssassi A. , Nguyen-Ba T. , Vaillancourt R.
Published: March 2010

The propagation of a dispersive shock wave is studied in a quintic-derivative nonlinear Schrödinger (Q-DNLS) equation, which may describe, for example, the wave propagation on a discrete electrical transmission line. It is shown that a physical system described by a Q-DNLS equation without a dissipative term may support the propagation of shock waves. The influence of the derivative nonlinearity terms on the shock is analyzed. Using the found exact shock solutions of the Q-DNLS equation as the initial input signal, we investigate numerically the spatiotemporal stability of the shock signal in the network.
Application of the “confusion principle” to Sn-based materials as negative electrode materials for Li-ion batteries
Authors: Ferguson P. P. , Dahn J. R.
Published: March 2010

The “confusion principle” (Greer. Nature, 366, 303 (1993)) is applied to tin-3d transition metals carbon alloys to obtain a nanostructured negative electrode material. Various Sn–TMs–C samples with TMs = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu (all included with same atomic ratios) were prepared by mechanical milling and by mechanical alloying. Each 10-component alloy sample was examined structurally using X-ray diffraction (XRD) and electrochemically using Li/Sn–TM–C cells. The sample Sn10TMs80C10 showed a nanostructured or amorphous-type XRD pattern, which shows the validity of this principle. XRD patterns of samples prepared with higher Sn atomic content showed crystalline features of Sn-based intermetallics. As expected, a very low specific capacity ( [Formula: see text]100 mAh/g) was observed for the sample Sn10TMs80C10. The sample Sn30TMs30C40 had the highest specific capacity (near 400 mAh/g) of the samples prepared. However, features of Sn aggregation were noticed at cycle number 80 of the latter sample, which are normally detrimental to the capacity retention upon further cycling.
On routing strategy with finite-capacity effect on scale-free networks
Authors: Tang Shaoting , Jiang Xin , Ma Lili , Zhang Zhanli , Zheng Zhiming
Published: March 2010

We propose a class of systems with finite-capacity effect to investigate routing-strategy optimization. The local topology and the variable capacity, two crucial elements for routing, are naturally coupled by considering the interactions among packets. We show how the combination of these two elements controls the normal and efficient functioning of routing in the frame of condensation and coverage, respectively. Specifically, it is shown that the dynamic behaviors of diffusing packets exhibit condensation, for which exact results of the stationary state and phase transition are given. Further, we explore the diffusion coverage of routed packets through simulation. Various alternatives for the strategy parameters are illustrated to apply standard techniques to alleviate condensation and accelerate coverage. Our results provide a practical way for the design of optimal routing strategies in complex networks by the manipulation of a few parameters.
FERMI–FRENET COORDINATES FOR SPACELIKE CURVES
Authors: UNDERWOOD MICHAEL S. , MARZLIN KARL-PETER
Published: March 2010

We generalize Fermi coordinates, which correspond to an adapted set of coordinates describing the vicinity of an observer's worldline, to the worldsheet of an arbitrary spatial curve in a static spacetime. The spatial coordinate axes are fixed using a covariant Frenet triad so that the metric can be expressed using the curvature and torsion of the spatial curve. As an application of Fermi–Frenet coordinates, we show that they allow covariant inertial forces to be expressed in a simple and physically intuitive way.
ANALYZING NONEXTENSIVITY OF η-SPECTRA IN RELATIVISTIC HEAVY ION COLLISIONS AT $\sqrt{s_{NN}} = 200~{\rm GeV}$
Authors: DE BHASKAR , SAU GOUTAM , BISWAS S. K. , BHATTACHARYYA S. , GUPTAROY P.
Published: March 2010

The transverse momentum spectra of secondary η particles produced in P+P, D + Au and Au + Au interactions at [Formula: see text] at different centralities have been studied in the light of a nonextensive thermodynamical approach. The results and the possible thermodynamical insights, thus obtained, about the hadronizing process have also been discussed in detail.
YES-GO CROSS-COUPLINGS IN COLLECTIONS OF TENSOR FIELDS WITH MIXED SYMMETRIES OF THE TYPE (3, 1) AND (2, 2)
Authors: BIZDADEA CONSTANTIN , CIOROIANU EUGEN-MIHĂIŢĂ , SALIU SOLANGE-ODILE , BĂBĂLÎC ELENA-MIRELA
Published: March 2010

Under the hypotheses of analyticity, locality, Lorentz covariance, and Poincaré invariance of the deformations, combined with the requirement that the interaction vertices contain at most two space–time derivatives of the fields, we investigate the consistent cross-couplings between two collections of tensor fields with the mixed symmetries of the type (3, 1) and (2, 2). The computations are done with the help of the deformation theory based on a cohomological approach in the context of the antifield-BRST formalism. Our results can be synthesized in: (i) there appear consistent cross-couplings between the two types of field collections at order one and two in the coupling constant such that some of the gauge generators and of the reducibility functions are deformed, and (ii) the existence or not of cross-couplings among different fields with the mixed symmetry of the Riemann tensor depends on the indefinite or respectively positive-definite behavior of the quadratic form defined by the kinetic terms from the free Lagrangian.
DIRICHLET CASIMIR ENERGY FOR A SCALAR FIELD IN A SPHERE: AN ALTERNATIVE METHOD
Authors: VALUYAN M. A. , GOUSHEH S. S.
Published: March 2010

In this paper we compute the leading order of the Casimir energy for a free massless scalar field confined in a sphere in three spatial dimensions, with the Dirichlet boundary condition. When one tabulates all of the reported values of the Casimir energies for two closed geometries, cubical and spherical, in different space–time dimensions and with different boundary conditions, one observes a complicated pattern of signs. This pattern shows that the Casimir energy depends crucially on the details of the geometry, the number of the spatial dimensions, and the boundary conditions. The dependence of the sign of the Casimir energy on the details of the geometry, for a fixed spatial dimensions and boundary conditions has been a surprise to us and this is our main motivation for doing the calculations presented in this paper. Moreover, all of the calculations for spherical geometries include the use of numerical methods combined with intricate analytic continuations to handle many different sorts of divergences which naturally appear in this category of problems. The presence of divergences is always a source of concern about the accuracy of the numerical results. Our approach also includes numerical methods, and is based on Boyer's method for calculating the electromagnetic Casimir energy in a perfectly conducting sphere. This method, however, requires the least amount of analytic continuations. The value that we obtain confirms the previously established result.
FADDEEV–POPOV GHOSTS
Authors: FADDEEV LUDVIG DMITRIEVICH
Published: March 2010

In the terminology of theoretical physics, the term "ghost" is used to identify an object that has no real physical meaning. The name "Faddeev–Popov ghosts" is given to the fictitious fields that were originally introduced in the construction of a manifestly Lorentz covariant quantization of the Yang–Mills field. Later, these objects acquired more widespread application, including in string theory.

The necessity of ghosts is associated with gauge invariance. In gauge invariant theories, one usually has to deal with local fields, whose number exceeds that of physical degrees of freedom. For example in electrodynamics, in order to maintain manifest Lorentz invariance, one uses a four component vector potential Aμ(x), whereas the photon has only two polarizations. Thus, one needs a suitable mechanism in order to get rid of the unphysical degrees of freedom. Introducing fictitious fields, the ghosts, is one way of achieving this goal.
SUBSTEPS OF KINESIN STUDIED WITH A NECK LINKER SWING MODEL
Authors: SHU YAO-GEN , LI MING
Published: March 2010

We have proposed the neck linker swing model to investigate the substeps of kinesin. The Michaelis–Menten-like curve for velocity versus ATP concentration at different loads has been obtained, which is in agreement with experiments. We have predicted that the Michaelis constant does not increase monotonically and an elastic instability will happen with increasing applied force.
MONTE CARLO SIMULATION OF STEADY-STATE TRANSPORT IN SUBMICROMETERInPANDGaAsn+–i(n)–n+DIODE
Authors: ARABSHAHI H. , ROKN-ABADI M. REZAEE , BAGHSIAHI F. BADIEIAN , KHALVATI M. R.
Published: March 2010

Monte Carlo simulation of electron transport in an InP diode of n+–i(n)–n+structure is compared with GaAs diode. The anode voltage ranges from 0.5 to 1.5 V. The distributions of electron energies and electron velocities and the profiles of the electron density, electric field and potential and average electron velocity are computed. Based on these data, the near ballistic nature of the electron transport in the 0.2 μm-long diode and the importance of the back-scattering of electrons from the anode n+-layer are discussed. In addition, the effects of the lattice temperature and doping on the length of the active layer are discussed. Electronic states within the conduction band valleys at the Γ, L, and X are represented by non-parabolic ellipsoidal valleys centered on important symmetry points of the Brillouin zone. Our simulation results have also shown that the electron velocity characteristics in InP diode are more sensitive to temperature than in other III–V semiconductors such as GaAs .
SADDLE-NODE BIFURCATION AND ITS CONTROL OF BURGERS–KdV EQUATION
Authors: TANG JIASHI , ZHAO MINGHUA , HAN FENG , FU WENBIN
Published: March 2010

The Burgers–Korteweg-de Vries (KdV) equation had been used as nonlinear modes for acoustic shock waves in dusty plasmas and so on. The variable transformation and the Jacobi elliptic function method was introduced to find the exact solution. In this paper, we will research into the saddle-node bifurcation and its control of the forced Burgers–KdV. By the transformation, PDEs are reduced to ODEs. Analyzing the frequency response function and its unstable region of the trivial steady state, we know that the saddle-node bifurcation which leads to jump and hysteresis may appear in the resonance response. Controllers for bifurcation modification purpose are designed in order to remove or delay the occurrence of jump and hysteresis phenomena. By means of numerical simulations we compare the uncontrolled system with the controlled system and clarify that controllers are adequate for the saddle-node bifurcation control of the forced Burgers–KdV equation.
WELL WIDTH-DEPENDENT ELECTRON RAMAN SCATTERING IN A SPHERICAL QUANTUM DOT
Authors: ZHONG QING-HU , YI XUE-HUA
Published: March 2010

Electron Raman scattering (ERS) is investigated in a CdS cylindrical spherical dot (QD). The different cross-section (DCS) is calculated as a function of the scattering frequency and the size of QD. Single parabolic conduction and valence bands are assumed. Singularities in the spectrum are found and interpreted. The selection rules for the processes are also studied. The ERS studied here can be used to provide direct information about the electron band structure of these systems.
BARIUM HEXAFERRITE THICK FILMS BY HOT PRESS SINTERING
Authors: JIANG H. C. , ZHANG W. L. , HE Y. , PENG B. , ZHANG W. X.
Published: March 2010

BaFe 12 O 19 ferrite thick films were screen-printed and sintered at 1150°C under pressure (hot press sintering). The effects of the hot press sintering on the properties of barium hexaferrite thick films were investigated. The X-ray diffraction pattern shows improvement of the (00l) texture under pressure. The porosity size of the hot press sintering samples decreases obviously and the surface compactness is improved as the pressure is increased. The films are quite anisotropic with magnetic easy axis perpendicular to the film plane. The largest remanence ratio achieved is 0.75 under the highest pressure of 4 MPa.
HAWKING-LIKE RADIATION AS TUNNELING FROM THE APPARENT HORIZON IN AN FRW UNIVERSE
Authors: ZHU TAO , REN JI-RONG , SINGLETON DOUGLAS
Published: March 2010

We study Hawking-like radiation in a Friedmann–Robertson–Walker (FRW) universe using the quasi-classical WKB/tunneling method, which pictures this process as a "tunneling" of particles from behind the apparent horizon. The correct temperature of the Hawking-like radiation from the FRW space–time is obtained using a canonical invariant tunneling amplitude. In contrast to the usual quantum-mechanical WKB/tunneling problem, where the tunneling amplitude has only a spatial contribution, we find that the tunneling amplitude for FRW space–time (i.e. the imaginary part of the action) has both spatial and temporal contributions. In addition we study backreaction and energy conservation of the radiated particles and find that the tunneling probability and the change in entropy, [Formula: see text], are related by the relationship [Formula: see text], which differs from the standard result, [Formula: see text]. By regarding the whole FRW universe as an isolated adiabatic system, the change in the total entropy is zero. Then, splitting the entropy between the interior and exterior parts of the horizon [Formula: see text], we can explain the origin of the minus sign difference with the usual result: our [Formula: see text] is for the interior region, while the standard result from black hole physics is for the exterior region.
OPTIMAL CONTROL MEASURES FOR TUBERCULOSIS MATHEMATICAL MODELS INCLUDING IMMIGRATION AND ISOLATION OF INFECTIVE
Authors: OKUONGHAE D. , AIHIE V. U.
Published: March 2010

Optimal control theory is applied to a system of ordinary differential equations modeling the population dynamics of tuberculosis with isolation and immigration of infective. Seeking to minimize the number of infectious individuals and reduce the transmission of the disease, we use controls to represent the screening/medical testing of infected immigrants into the population as well as isolation of infective in the population. The optimal controls are characterized in terms of the optimality system, which is solved numerically for several scenarios using an iterative method with Runge-Kutta fourth order scheme. Parameter values used are those reported for Nigeria.
DYNAMICS OF THE TRANSITION TO PATHOGENICITY INERWINIA CHRYSANTHEMI
Authors: KEPSEU WILFRED D. , WOAFO PAUL , SEPULCHRE JACQUES-A.
Published: March 2010

The enterobacteria Erwinia chrysanthemi and other soft-rot Erwiniae cause soft-rot disease in plants by secreting extracellular enzymes among which the main virulence factors are pectate lyases (Pels). These pectic enzymes are produced by the activation of the pel genes whose transcription is controlled by a complex regulatory network. Using the knowledge acquired in a previous work, a simplified regulatory network is proposed, keeping only the key variables for the transition to pathogenicity. We identify that the core mechanism for the onset of Pel is governed by a small metabolico-genetic network involving the repressor KdgR and the inductor KDG. Next we consider that the triggering of Pel synthesis is relayed by a quorum sensing (QS) phenomenon describing the ability of bacteria to use the size and density of their colonies to regulate the production of pectate lyases. The simplified network is described by only a few differential equations, thereby allowing the use of standard bifurcation analysis in the phase space. From this modeling emerges a qualitative but generic mechanism for the transition to virulence of a pectinolytic bacterium when it infects a plant.
UNSUPERVISED SEGMENTATION OF COLLAGEN FIBER DISTRIBUTION IN DIFFERENT STAGES OF OSF
Authors: RAY TATHAGATA , CHATTERJEE JYOTIRMOY , MUKHERJEE ANIRBAN , PAL MOUSUMI , CHAUDHURI KEYA , PAUL RANJAN RASHMI , DUTTA PRANAB K.
Published: March 2010

The objective of this paper is to describe the comparative efficacy of three signal processing-based feature extraction methodologies for classifying normal oral mucosa, early and advanced stages of Oral Submucous Fibrosis (OSF) by unsupervised segmentation of sub-epithelial collagen fibers. Wavelet and discrete cosine transform (DCT) based energy features are extracted from Transmission Electron Micrographs (TEM) of collagen fibers of different stages of OSF in non overlapping blocks which in turn are classified by fuzzy c-means clustering. The overall efficacy of DCT-based features have been found better in comparison to its wavelet-based counterpart.
ARSENIC ACCUMULATION IN PLANTS – OUTLINING STRATEGIES FOR DEVELOPING IMPROVED VARIETY OF CROPS FOR AVOIDING ARSENIC TOXICITY IN FOODS
Authors: LUNDH DAN , LARSSON DENNIS , NAHAR NOOR , MANDAL ABUL
Published: March 2010

Contamination of food with arsenics is a potential health risk for both humans and animals in many regions of the world, especially in Asia. Arsenics can be accumulated in humans, animals and plants for a longer period and a long-term exposure of humans to arsenics results in severe damage of kidney, lever, heart etc. and many other vascular diseases. Arsenic contamination in human may also lead to development of cancer. In this paper we report our results on data mining approach (an in silico analysis based on searching of the existing genomic databases) for identification and characterization of genes that might be responsible for uptake, accumulation or metabolism of arsenics. For these in silico analyses we have involved the model plant Arabidopsis thaliana in our investigation. By employing a system biology model (a kinetic model) we have studied the molecular mechanisms of these processes in this plant. This model contains equations for uptake, metabolism and sequestration of different types of arsenic; As(V), As(III), MMAA and DMAA. The model was then implemented in the software XPP. The model was also validated against the data existing in the literatures. Based on the results of these in silico studies we have developed some strategies that can be used for reducing arsenic contents in different parts of the plant. Data mining experiments resulted in identification of two candidate genes (ACR2, arsenate reductase 2 and PCS1, phytochelatin synthase 1) that are involved either in uptake, transport or cellular localization of arsenic in A. thaliana. However, our system biology model revealed that by increasing the level of arsenate reductase together with an increased rate of arsenite sequestration in the vacuoles (by involving an arsenite efflux pump MRP1/2), it is possible to reduce the amount of arsenics in the shoots of A. thaliana to 11–12%.
QUANTIFYING TREE DIAMETER DISTRIBUTIONS WITH ONE-DIMENSIONAL DIFFUSION PROCESSES
Authors: RUPŠYS PETRAS , PETRAUSKAS EDMUNDAS
Published: March 2010

This study presents diffusion processes methodology on tree diameter distribution problem. We use stochastic differential equation methodology to derive a univariate age-dependent probability density function of a tree diameter distribution. The purpose of this paper is to investigate the relationship between the stochastic linear and logistic shape diameter growth models and diameter distribution laws. We establish the probabilistic characteristics of stochastic growth models, such as the univariate transition probability density of tree diameter, the mean and variance of tree diameter. We carry out comparison of proposed continuous time stochastic models on the basis of Hong-Li, Gini, Shapiro-Wilk goodness-of-fit statistics and normal probability plot. Parameter estimations are based on discrete observations over age of trees. To model the tree diameter distribution, as an illustrative experience, a real data set from repeated measurements on a permanent sample plot of pine (Pinus sylvestris) stand in the Kazlu Ruda district at Lithuania is used. The results are implemented in the symbolic computational language MAPLE.
A PARALLEL SCHEME FOR COMPARING TRANSCRIPTION FACTOR BINDING SITES MATRICES
Authors: CARAT SOLENNE , HOULGATTE RÉMI , BOURDON JÉRÉMIE
Published: March 2010

Gene regulation implies many mechanisms. Their identification is a crucial task to construct regulatory networks, and is necessary to understand the pathology in many cases. This requires the identification of transcription factors that play a role in regulation. Numerous motif discovery tools are now available. Combining efficiently their results appears useful for comparing and clustering these motifs in order to reduce redundancies and to identify the corresponding transcription factor. We develop a method that produces, compares and clusters a set of motifs and identifies some close motifs in databases like JASPAR and the public version of Transfac. Unlike previous comparison methods, where each matrix column is compared independently, we have developed a global method to compare motifs that also helps to reduce the number of false positives. We also propose an original graph motif model that generalizes the classical position specific pattern matrices. Finally, we present an application of our method to study ChIP-chip data sets in the context of an eukaryotic organism.
A COMPARATIVE ANALYSIS OF FOLDING PATHWAYS OF THERMOPHILIC AND MESOPHILIC PROTEINS BY MONTE CARLO SIMULATIONS
Authors: GLYAKINA ANNA V. , GALZITSKAYA OXANA V.
Published: March 2010

In this work we have studied the folding pathways for four pairs of homologous proteins from thermophilic and mesophilic organisms from two different structural classes (class a, all-α proteins and class d, α + β proteins) using Monte Carlo simulations. We have obtained 50 trajectories for each protein and followed the free-energy profile and the order of folding of secondary structure elements between the last occurrence of the completely unfolded state and the first occurrence of the completely folded state. It turns out that the period of successful crossing of the free-energy barrier between unfolded and folded states for 40–45 trajectories (80–90%) makes 10% of the total folding time for four proteins (1tzvA, 1eyvA, 351c, and 1t4aA) and only 0.1% for two proteins (1dd3, 1ctf). This observation can be explained by a higher free-energy barrier for these proteins (1dd3, 1ctf) in comparison with other studied proteins. We have observed that folding pathways of thermophilic and mesophilic proteins may be the same, partly the same, and different. And similarity or difference between the folding pathways of thermophilic and mesophilic proteins does not depend on the structural class to which these proteins belong. Folding pathways for proteins from both classes correlate with the calculated folding nuclei for these proteins.
COMBINING STATISTICAL AND GEOMETRIC FEATURES FOR COLONIC POLYP DETECTION IN CTC BASED ON MULTIPLE KERNEL LEARNING
Authors: WANG SHIJUN , YAO JIANHUA , PETRICK NICHOLAS , SUMMERS RONALD M.
Published: March 2010

Computed tomographic colonography (CTC) combined with a computer aided detection system provides a feasible approach for improving colonic polyps detection and increasing the use of CTC for colon cancer screening. To distinguish true polyps from false positives, various features extracted from polyp candidates have been proposed. Most of these traditional features try to capture the shape information of polyp candidates or neighborhood knowledge about the surrounding structures (fold, colon wall, etc.). In this paper, we propose a new set of shape descriptors for polyp candidates based on statistical curvature information. These features called histograms of curvature features are rotation, translation and scale invariant and can be treated as complementing existing feature set. Then in order to make full use of the traditional geometric features (defined as group A) and the new statistical features (group B) which are highly heterogeneous, we employed a multiple kernel learning method based on semi-definite programming to learn an optimized classification kernel from the two groups of features. We conducted leave-one-patient-out test on a CTC dataset which contained scans from 66 patients. Experimental results show that a support vector machine (SVM) based on the combined feature set and the semi-definite optimization kernel achieved higher FROC performance compared to SVMs using the two groups of features separately.
THE SHAKY LADDER HYPERPLANE-DEFINED FUNCTIONS AND CLASSIC DYNAMIC PROBLEMS
Authors: ALHARBI ABIR , RAND WILLIAM
Published: March 2010

To improve the understanding of the GA in dynamic environments we explore a set of test problems, the shaky ladder hyper-defined functions (sl-hdf), and extend these functions to create versions that are equivalent to many classical dynamic problems. We do this by constraining the space of all sl-hdfs to create representations of these classical functions. We have examined three classical problems, and compared sl-hdf versions of these problems with their standard representations. These results show that the sl-hdfs are representative of a larger class of problems, and can represent a larger class of test suite. Previous results on sl-hdf showed that GA performance is best in the Defined Cliffs variant of the sl-hdf. We build upon these results to improve GA performance in several classes of real world dynamic problems by modifying the problem representation. These results lend insight into dynamic problems where the GA will perform well.
MIXED GENETIC ALGORITHM APPROACH FOR FUZZY CLASSIFIER DESIGN
Authors: DEVARAJ D. , GANESH KUMAR P.
Published: March 2010

An important issue in the design of FRBS is the formation of fuzzy if-then rules and the membership functions. This paper presents a Mixed Genetic Algorithm (MGA) approach to obtain the optimal rule set and the membership function of the fuzzy classifier. While applying genetic algorithm for fuzzy classifier design, the membership functions are represented as real numbers and the fuzzy rules are represented as binary string. Modified forms of crossover and mutation operators are proposed to deal with the mixed string. The proposed genetic operators help to improve the convergence of GA and accuracy of the classifier. The performance of the proposed approach is evaluated through development of fuzzy classifier for seven standard data sets. From the simulation study it is found that the proposed algorithm produces a fuzzy classifier with minimum number of rules and high classification accuracy. Statistical analysis of the test results shows the superiority of the proposed algorithm over the existing methods.
HYBRID APPROACH FOR BRAIN TUMOR SEGMENTATION IN MAGNETIC RESONANCE IMAGES USING CELLULAR NEURAL NETWORKS AND OPTIMIZATION TECHNIQUES
Authors: SELVATHI D. , SELVARAJ HENRY , SELVI S. THAMARAI
Published: March 2010

Tumor segmentation from brain magnetic resonance image data is an important but time consuming task performed manually by medical experts. Automating this process is challenging due to the high diversity in appearance of tumor tissue among different patients and in many cases, similarity between tumor and normal tissue. This paper deals with an efficient segmentation algorithm for extracting brain tumors in magnetic resonance images using Cellular Neural Networks (CNN). Learning CNN templates values are formulated as an optimization problem. The template coefficients (weights) of an CNN which will give a desired performance, can be derived by learning genetic algorithm and simulated annealing optimization techniques. The objective of this work is to compare the performance of genetic algorithm (GA) and simulated annealing (SA) for finding the optimum template values in the CNN which is used for segmenting the tumor region in the abnormal MR images. The method is applied on real data of MRI images of thirty patients with four different types of tumors. The results are compared with radiologist labeled ground truth. Quantitative analysis between ground truth and segmented tumor is presented in terms of segmentation efficiency. From the analysis and performance measures like segmentation accuracy, it is inferred that the brain tumor segmentation is best done using CNN with genetic algorithm template optimization than CNN with simulated annealing template optimization. An average accuracy rate of above 95% was obtained using this segmentation algorithm.
Semantic foundations for typed assembly languages
Authors: Ahmed Amal , Appel Andrew W. , Richards Christina D. , Swadi Kedar N. , Tan Gang , Wang Daniel C.
Published: March 2010

Typed Assembly Languages (TALs) are used to validate the safety of machine-language programs. The Foundational Proof-Carrying Code project seeks to verify the soundness of TALs using the smallest possible set of axioms: the axioms of a suitably expressive logic plus a specification of machine semantics. This article proposes general semantic foundations that permit modular proofs of the soundness of TALs. These semantic foundations include Typed Machine Language (TML), a type theory for specifying properties of low-level data with powerful and orthogonal type constructors, and
L

c

, a compositional logic for specifying properties of machine instructions with simplified reasoning about unstructured control flow. Both of these components, whose semantics we specify using higher-order logic, are useful for proving the soundness of TALs. We demonstrate this by using TML and
L

c

to verify the soundness of a low-level, typed assembly language, LTAL, which is the target of our core-ML-to-sparc compiler.

To prove the soundness of the TML type system we have successfully applied a new approach, that of
step-indexed logical relations
. This approach provides the first semantic model for a type system with updatable references to values of impredicative quantified types. Both impredicative polymorphism and mutable references are essential when representing function closures in compilers with typed closure conversion, or when compiling objects to simpler typed primitives.
A termination analyzer for Java bytecode based on path-length
Authors: Spoto Fausto , Mesnard Fred , Payet Étienne
Published: March 2010

It is important to prove that supposedly terminating programs actually terminate, particularly if those programs must be run on critical systems or downloaded into a client such as a mobile phone. Although termination of computer programs is generally undecidable, it is possible and useful to prove termination of a large, nontrivial subset of the terminating programs. In this article, we present our termination analyzer for sequential Java bytecode, based on a program property called
path-length
. We describe the analyses which are needed before the path-length can be computed such as sharing, cyclicity, and aliasing. Then we formally define the path-length analysis and prove it correct with respect to a reference denotational semantics of the bytecode. We show that a constraint logic program
P

CLP

can be built from the result of the path-length analysis of a Java bytecode program
P
and formally prove that if
P

CLP

terminates, then
P
also terminates. Hence a termination prover for constraint logic programs can be applied to prove the termination of
P
. We conclude with some discussion of the possibilities and limitations of our approach. Ours is the first existing termination analyzer for Java bytecode dealing with any kind of data structures dynamically allocated on the heap and which does not require any help or annotation on the part of the user.