quasi-static coronal evolution: Topics by WorldWideScience.org

Spin Modulation in Semiconductor Lasers

To study the three-dimensional (3D) magnetic field topology and its long-term evolution associated with the X3.4 flare of 2006 December 13, we investigate the coronal relative magnetic helicity in the flaring active region (AR) NOAA 10930 during the time period of December 8-14. The coronal helicity is calculated based on the 3D nonlinear force-free magnetic fields reconstructed by the weighted optimization method of Wiegelmann, and is compared with the amount of helicity injected through the photospheric surface of the AR. The helicity injection is determined from the magnetic helicity flux density proposed by Pariat et al. using Solar and Heliospheric Observatory/Michelson Doppler Imager magnetograms. The major findings of this study are the following. (1) The time profile of the coronal helicity shows a good correlation with that of the helicity accumulation by injection through the surface. (2) The ...

2010-09-10

3

On the Stefan Problem with Volumetric Energy Generation

We provide an analytic study of the dynamics of semiconductor lasers with injection (pump) of spin-polarized electrons, previously considered in the steady-state regime. Using complementary approaches of quasi-static and small signal analyses, we elucidate how the spin modulation in semiconductor lasers can improve performance, as compared to the conventional (spin-unpolarized) counterparts. We reveal that the spin-polarized injection can lead to an enhanced bandwidth and desirable switching properties of spin-lasers.

2010-01-01

4

A study of the breakdown of the quasi-static approximation at high densities and its effect on the helium-like K ALPHA complex of nickel, iron, and calcium

This paper presents results of solid-liquid phase change, driven by volumetric energy generation, in a vertical cylinder. We show excellent agreement between a quasi-static, approximate analytical solution valid for Stefan numbers less than one, and a computational model solved using the CFD code FLUENT®. A computational study also shows the effect that the volumetric energy generation has on both the mushy zone thickness and convection in the melt during phase change.

2009-11-01

5

Rotational modes of motion for an aerodynamic pendulum with a vertical rotation axis

The General Spectral Modeling (GSM) code employs the quasi-static approximation, a standard, low-density methodology that assumes the ionization balance is separable from a determination of the excited-state populations that give rise to the spectra. GSM also allows for some states to be treated only as contributions to effective rates. While these two approximations are known to be valid at low densities, this work investigates using such methods to model high-density, non-LTE emission spectra and determines at what point the approximations break down by comparing to spectra produced by the LANL code ATOMIC which makes no such approximations. As both approximations are used by other astrophysical and low-density modeling codes, the results should be of broad interest. He-like K$\\alpha$ emission spectra are presented for Ni, Fe, and Ca, in order to gauge the effect of both approximations employed in GSM. This work confirms that at and above the temperature of ...

2007-01-01

6

British Library Electronic Table of Contents (United Kingdom)

An aerodynamic pendulum placed in a steady horizontal air flow is studied in connection with modeling a wind-receiving element of a vertical-axis wind turbine (VAWT). When modeling the medium effects on the pendulum, the following two approaches are combined: the quasi-static one based on stationary wind tunnel experiments and the unsteady one based on the added mass effects. The existence of stable and unstable rotational modes is analyzed analytically (via the Poincar?-Pontryagin method) and numerically. The dependence on the parameters responsible for the viscous friction at the rotation axis and for the added mass effects is taken into account.

2009-01-01

7

Investigation of subsurface exploration methods for prevailing geologic conditions in South Carolina

Dynamic stability and vibration monitoring for No. 9 mine, M-1 dump

Subsurface conditions at sites in the coastal plains region of South Carolina were investigated using standard penetration and mechanical quasi-static cone penetration tests. The penetration test results are compared with measured static axial pile capacity. The cone penetration test results are compared with stratigraphy and soil types encountered at each site. Results show that with certain limitations, cone penetration test results can be used to assess general stratigraphy and soil type and predict static axial pile capacity with reasonable accuracy.

1985-11-01

8

The Dynamical Interaction of AGN with their Galaxian Environments

This study examines the effects of blasting on waste dumps at open pit mining operations. Of specific concern were mining operations at the base of a five hundred foot high waste dump such as the operation at the South Pit of the Smoky-River Coal Ltd. property near Grande Cache, Alberta. An assessment of waste dump stability including factors such as quasi-static deformation behaviour, historical dump deformation behaviours and potential blasting effects was undertaken. It is concluded that safe blasting may be carried out in proximity to waste dumps, but monitoring of dump behaviour is recommended to ensure operational safety. 22 refs., 4 apps.

1988-11-01

9

High-tension corona controlled ozone generator for environment protection

Jet-driven shocks are responsible for an important fraction of the emission of the narrow-line regions (NLRs) in many classes of AGN. However, this cannot explain all observations. It is clear that the remaining sources are photoionised by the active nucleus. The 2-d hydrodynamic models from the RSAA group support an evolutionary scenario whereby the shock-excited NLRs are initially jet-driven but later, ionizing photons from the central engine replace shocks as the main excitation mechanism and shock induced star formation may also become important. In their photoionized phase, dusty and radiation-pressure dominated evolution produces a self-regulated NLR spectrum. This model aso explains the coronal emission lines and fast (3000 km s$^{-1}$) outflows seen in some Seyferts.

2003-01-01

10

The response of small scale rigid targets to shallow buried explosive detonations

Engineering details of a high voltage driven corona-plasma ozone generator are described. The plasma diode of generator has coaxial cylindrical geometry with cathode located inside anode. Cathode is made of a large number of radial gas nozzles arranged on central tubular mast which admits oxygen gas. The sharp endings of the nozzles along with a set of corona rings create the high electric field at the cathode required for formation of dense corona plume responsible for O_3 evolution. A model of coronal plasma generation and ozone production is presented. The plasma formation is strongly dependent on the electric field and temperature in side diode where a high electron density in a low temperature negative corona is suited for high ozone yields. These are established by suitable regulation of A-K gap, voltage, oxygen pressure, and cathode-nozzle population.

2010-02-01

11

British Library Electronic Table of Contents (United Kingdom)

Experimental and computational investigations were performed in order to better understand the mechanical response of rigid targets with various geometries to the detonation of shallow buried explosives. The motion of the targets was measured by use of high-speed digital video photography. This work involved flat targets, targets that were downwardly convex, and targets that were downwardly concave with explosive charges located at various positions beneath the targets. It was observed that, in general, angled hulls - whether downwardly concave or convex - tended to reduce the amount of momentum imparted to the center of mass of the targets. Computations were performed by use of an arbitrary Langrangian-Eulerian treatment in a nonlinear finite element code. A model based on quasi-static te...

2011-01-01

12

The response of clamped-clamped microbeams under mechanical shock

British Library Electronic Table of Contents (United Kingdom)

We present modeling, simulation, and characterization for the dynamic response of clamped-clamped microbeams under mechanical shock. A Galerkin-based reduced-order model is utilized and its results are verified by comparing to finite-element results. The results indicate that the response of a microbeam to mechanical shock is inherently non-linear because of the dominating effect of mid-plane stretching. The effect of the shock pulse shape is investigated. It is concluded that the shape of the shock pulse can result in significant dynamic amplification in the response of the microbeam even in cases where the shock load is considered quasi-static.The combined effect of the electrostatic force and mechanical shock is investigated. The results show that this combined effect can lead to early ...

2007-01-01

13

Negative group velocity from resonances in two-dimensional phononic crystals

British Library Electronic Table of Contents (United Kingdom)

We investigate two routes to obtain negative group velocity bands in two-dimensional phononic crystal structures. The negative dispersion originates from the resonances of sub-wavelength building blocks and as such, the system should be regarded as acoustic metamaterials. The first kind of acoustic metamaterial exhibits effectively negative bulk modulus and negative mass density simultaneously. Monopolar and dipolar Mie resonances are combined to achieve an effective medium with negative refractive index. In particular, we present a double negative metamaterial for airborne sonic waves. We then show that we can obtain negative group velocity from quadrupole resonances, and the result is explained using the quasi-static approximation. The negative dispersion in quadrupole bands cannot be de...

2010-01-01

14

Behavior of particle-filled polymer composite under static and dynamic loading

British Library Electronic Table of Contents (United Kingdom)

Experimental results of quasi-static and dynamic fracture of particle-filled polymer composite (PFPCM) "ALTUGLAS EI CH25" with a matrix of polymethylmethacrylate (PMMA) are reported in this paper. PMMA matrix is filled with rubber particles, as result a shock-resistant transparent composite is produced. The main task was to investigate experimentally and theoretically the fracture toughness of this composite under static and dynamic loading. A high-rate loading has been created by impulse magnetic field. Analysis of fracture process and its relation with the load parameters and material microstructure have been established. Application of the original testing method enabled determination of fracture toughness at very short loading times and comparison of the results with material dynamic p...

2008-01-01

15

Approximate solutions to the Stefan problem with internal heat generation

Analysis of in-situ fracture of oil sand formations by explosives

Using a quasi-static approach valid for Stefan numbers less than one, we derive approximate equations governing the movement of a phase change front for materials which generate internal heat. These models are applied for both constant surface temperature and constant surface heat flux boundary conditions, in cylindrical, spherical, plane wall and semi-infinite geometries. Exact solutions with the constant surface temperature condition are obtained for the steady-state solidification thickness using the cylinder, sphere, and plane wall geometries which show that the thickness depends on the inverse square root of the internal heat generation. Under constant surface heat flux conditions, closed form equations can be obtained for the three geometries. In the case of the semi-infinite wall, we show that for constant temperature and constant heat flux out of the wall conditions, the solidification layer grows then remelts. (orig.)

2008-05-15

16

National Advisory Committee for Aeronautics 1952 - NASA Technical ...

An analytical model is proposed for the design and simulation of in-situ fracture of deep oil sand formations. This model is based on the finite element variational principle in conjunction with special empirical modules to characterize in-situ oil sands behavior. A computer code by the name of SANFRAC was developed to handle the dynamic fracture of formations induced by explosives. Simulation of hydraulic fracture processes can be treated by the same code as special cases using the quasi-static analysis. Numerical case studies by the SANFRAC code indicate that extensive horizontal fracture can be achieved by dynamic loads with proper fracture starters configured at the injection well. The unique advantage of the dynamic fracturing technique over the hydraulic fracture methods is also demonstrated by these studies.

1987-03-01

17

Granular flow considerations in the design of a cascade solid breeder reaction chamber

By Charles E. Watkins. 2458. An Instrument Employing a Coronal Discharge for ..... Grover, W. S. Hyler, and L. R. Jackson. 2640. Interaction of Column and ...

18

Electrical properties of inalp native oxides for metal-oxide-semiconductor device applications

Both horizontally and vertically oriented rotating chambers with granular material held on the inner surface by centrifugal action are examined. Modifications to the condition for controlled quasi-static flow on an incline plane, phi/sub w/ < #alpha# < phi/sub r/, where phi/sub w/ is the wall friction angle, #alpha# is the angle of inclination of the plane, and phi/sub r/ is the drained angle of repose of the material are examined for the case of horizontal and vertical surfaces of revolution. Allowed included half angles for horizontally oriented chambers are likely to be in the range of 30"0 +- 10"0 for ceramic particles and metal surfaces. For vertical orientations the maximum half-angle of the top cone is slightly less than the wall friction angle phi/sub w/ while the lower portion can have a half angle as large as (90"0 - phi/sub w). Percolation of fines through shearing granular solids is briefly discussed and recommended experimental and calculational ...

1970-05-01

19

Introduction to Three Dimensional Reconstruction of Brain C. T. Image

Data are presented on the insulating properties and capacitance-voltage (CV) characteristics of metal-oxide-semiconductor (MOS) device-thickness (below approx. 100 nm) native oxides formed by wet thermal oxidation of thin InAlP epilayers lattice matched to GaAs. Low leakage current densities of J=1.4 x 10-9 A/cm2 and J=8.7 x 10-11 A/cm2 are observed at an applied field of 1 MV/cm for MOS capacitors fabricated with 17 nm and 48 nm oxides, respectively. TEM images show that the In-rich interfacial particles which exist in 110 nm oxides are absent in 17 nm oxide films. Quasi-static capacitance-voltage measurements of MOS capacitors fabricated on both n-type and p-type GaAs show that the InAlP oxide-GaAs interface is sufficiently free of traps to support inversion, indicating an unpinned Fermi level. These data suggest that InAlP native oxides may be a viable insulator for GaAs MOS device applications.

2004-09-01

20

The kinematics of coronal mass ejections using multiscale methods

The reconstruction of coronal and Sagittal Image of Brain C. T. is helpful to diagnosis of Brain. Three Dimensional Reconstruction software package allows to display three dimensional Image clerived from a series of Horizontal, Sagittal and Coronal Brain C. T. images. It useful in determine approach of operation, to define portals of deep radiation therapy.

1986-11-01

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Tensile strain limits of buried defects in pipeline girth welds

The diffuse morphology and transient nature of coronal mass ejections (CMEs) make them difficult to identify and track using traditional image processing techniques. We apply multiscale methods to enhance the visibility of the faint CME front. This enables an ellipse characterisation to objectively study the changing morphology and kinematics of a sample of events imaged by the Large Angle Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) and the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) onboard the Solar Terrestrial Relations Observatory (STEREO). The accuracy of these methods allows us to test the CMEs for non-constant acceleration and expansion. We exploit the multiscale nature of CMEs to extract structure with a multiscale decomposition, akin to a Canny edge detector. Spatio-temporal filtering highlights the CME front as it propagates in time. We apply an ellipse ...

2009-01-01

22

Mechanics and mechanisms of cyclic fatigue-crack propagation in transformation-toughened zirconia ceramics

There are currently no accepted industry standards for the tensile strain limits of girth welds. This paper investigated the behavior of girth welds with buried defects subjected to high longitudinal strains caused by soil movement. A strain design methodology based on a crack driving method was used to examine the factors influencing stain limits along with a constraint-sensitive fracture mechanics approach. No strength undermatching was used in the welds, and the defect location had no influence on crack driving force. The weld joint was assumed to have uniform tensile properties. A 3D finite element (FE) model was used to simulate pipe behavior. Symmetric boundary conditions were imposed on the symmetry planes, and uniform remote axial displacement was applied as the primary loading. Automated data processing routines were developed to extract and analyze the data. The crack driving force was computed directly from a crack tip deformation profile at the deepest point of the defect ...

2004-07-01

23

Influence of two changes in the composition of an acrylic bone cement on its handling, thermal, physical, and mechanical properties.

Damage and cyclic fatigue failure under alternating loading in transformation-toughened zirconia ceramics is reviewed and compared to corresponding behavior under quasi-static loading (static fatigue). Current understanding of the role of transformation toughening in influencing cyclic fatigue-crack propagation behavior is examined based on studies which altered the extent of the tetragonal-to-monoclinic phase transformation in MG-PSZ through subeutectoid aging. These studies suggest that near-tip computations of the crack-driving force (in terms of the local stress intensity) can be used to predict crack-growth behavior under constant amplitude and variable-amplitude (spectrum) loading, using spatially resolved Raman spectroscopy to measure the extent of the transformation zones. In addition, results are reviewed which rationalize distinctions between the crack-growth behavior of preexisting, long'' (> 2 mm), through-thickness cracks and ...

1992-05-01

24

High strain rate properties of composites

This study is a contribution to the growing body of work on the influence of changes in the composition of an acrylic bone cement on various properties of the curing and cured material. The focus is on one commercially-available acrylic bone cement brand, Surgical Simplex P, and three variants of it and a series of properties, namely, setting time, maximum exotherm temperature, activation energy and frequency factor for the polymerization reaction, diffusion coefficient for the uptake of phosphate buffered saline, at 37 degrees C, ultimate compressive strength (UCS), plane-strain fracture toughness, fatigue life (under fully-reversed tension-compression stress), hardness (H) and elastic modulus (both determined using quasi-static nanoindentation), and the variation of the storage and loss moduli with frequency of the applied force in a dynamic nanoindentation test. It was found that (a) a 68% reduction in the volume of the activator, N,N dimethyl-4-toluidine, ...

2007-05-05

25

Early detection of damage and analysis of damage development in metal structural components. Schaedigungsfrueherkennung und Schadensablauf bei metallischen Bauteilen

Polymer matrix composites are presently used in many fields due to their excellent mechanical properties such as high specific strength and stiffness. However, not much is known of these composites' response to impact loading, which usually occurs at strain rates much higher than the strain rates used to measure the quasi-static mechanical properties of materials. The use of static properties in the study of structures that undergo dynamic loading can produce excessive design weight or cause unexplained and untimely failure. The studies included in this dissertation provide the results of Split Hopkinson Pressure Bar experiments to determine the ultimate compressive strength and strain of composites at high strain rates. Most researchers are using specimens with different dimensions and geometry. For this reason, it is difficult to compare results of tests done by different people. Herein, the Split Hopkinson Pressure Bar facility at the University of Delaware is ...

1998-01-01

26

The topics of these short lectures on the subject of cyclic stress were: Microstructural mechanisms of damage accumulation under a multistage cyclic stress until incipient cracking; influence of surface decarbonizing phenomena on the failure behaviour of steel construction parts subjected to cyclic stress; thermocyclic fatigue of pipe samples of austenitic steel 1.4436; studies on surface structuring, microstructure and fatigue in LCF area. The short lectures on effects of quasi-static and creep stress were: Shear fracture in AlMg alloys as a result of local plastic instability; study of formation and growth of pores for an early recognition of damage and the course of damage in heat-resistant steels under creep test; experimental and numeric studies of the infuence of the microstructure on the course of damage during shear fractures of steel; numerical modelling of ductile fractures on the basis of micromechanical models. Under the topic of tribological stress the ...

1989-01-01

27

In the News...

"Ejections. "Massive Star Evolution. "Binary Star Evolution ..... Binary Star Evolution. Stars in binary systems evolve individually and together ...

28

Unclas

Neutron star evolution with internal heating

Another difference lies in the speed of star evolution. 2. Computation of Stellar Structure and Their Evolution. The structure of stars at certain instants ...

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Massive star evolution and SN 1987A

The thermal evolution predicted by current models of the superfluid-crust interaction is noted to

1989-01-01

30

Geothermal Evolution of the Astrakhan Crest Region of the Pricaspian Basin, Russia

The evolution of massive stars through hydrogen and helium burning is addressed. A set of stellar

1991-01-01

31

Evolution of ultraviolet dwarfs

Geothermal Evolution of the Astrakhan Crest Region of the Pricaspian Basin, Russia

2006-01-01

32

The static indentation behavior of composite sandwich panels with thin quasi-isotropic skins

UV dwarf star evolution, using central and gap star models emphasizing photoneutrino emission

1969-01-01

33

The quasi-static normal indentation of sandwich panels with quasi-isotropic laminated composite skins and honeycomb or foam cores, by spherical indentors, has been investigated using experiments and finite element analysis. The experimental program emphasized the effects of indentor size on the resulting load indentation responses, failure mechanisms in the skin and the core, and the measurement of contact areas between indentor and the target. The sandwich panels were indented up to the initiation of skin fracture and the resulting contact data was used to characterize contact power laws. A non-linear finite element model was developed based on the experimental observations to systematically explore the indentation behavior of diverse sandwich configurations and to investigate the contact pressure distributions. The finite element model was used as an experimental tool in the development of a simple non-dimensional semi-empirical model that was based on the ...

2001-01-01

34

NAME=\\

Interventional Procedures in Superficial Lesions: The Value of 2D with Additional Coronal Reformatted 4D Ultrasonography Guidance

...the huge volumes of ephemera amassed by the Colonial Office to record the coronation celebrations of 1937 and 1953 to the small illustrated manuscript account of Tobago penned by its governor in 1810, from one of the first European accounts of Ethiopia to be published to Winston Churchillrsquo;s valedictory letter of 1922 to Colonial Office staff, the exhibits provide a snapshot of the riches to be explored within this matchless collection. Explore ...

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CORONAL OBSERVATIONS OF CMEs Report of Working Group A

ObjectiveWe wanted to assess the usefulness of four-dimensional (4D) ultrasonography (US), i.e., real-time three-dimensional US, as an adjunct for performing various US-guided interventional...Full Text Available

2006-01-01

36

Stellar evolution. II - The evolution of a 3 sun-mass star from the main sequence through core helium burning.

imaging of the solar corona began in 1960 via a primitive pinhole camera on a ... IR wavelengths. Such data help us to study in detail the pre-eruptive ...... Schematic picture of flare loops, CME, and the current sheet between ..... As part of NASA's Living With a Star (LWS) program the planned Sentinel mission ...

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GALAXY EVOLUTION EXPLORER (GALEX) GUEST ... - GALEX - NASA

Three Sun-mass star evolution from main sequence to helium exhaustion in core, noting chronology of

1965-01-01

38

GALAXY EVOLUTION EXPLORER (GALEX) - HEASARC - NASA

star evolution, globular cluster structure and evolution, massive stars, supernova remnants, reflection nebulae, interstellar dust, structure of the ISM, ...

39

GALAXY EVOLUTION EXPLORER (GALEX) - GALEX - NASA

These include, but are not limited to: stellar winds and outflows, post-main- sequence stellar evolution, binary/multiple star evolution, globular cluster structure ...

40

These include, but are not limited to: stellar winds and outflows, post-main- sequence stellar evolution, binary/multiple star evolution, globular cluster structure ...

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Nobel prizes

A Study on the Convergence of the Evolution Strategies based on Learning

The nuclear reactions are described which govern the stellar evolution.

1983-12-01

42

KoreaScience (Korea)

Full Text Available

1999-12-01

43

In The News ... - NASA

Antineutrino burst in the hot-quark-star evolution with diquark condensate; Antineutrino Burst in der Evolution heisser Quarksterne mit Diquarkkondensat

Binary Star Evolution. Stars in binary systems evolve individually and together. " individually: evolution follows normal progression based on ...

44

The role of computed tomography in complex facial trauma

No abstract prepared.

2003-07-01

45

Spiral CT with three-dimensional and multiplanar reconstruction in the diagnosis of anterior chest wall joint and bone disorders

Tridimensional localization of bone and soft tissue injuries in complex facial trauma is fundamental for treatment. The face can be conceptualized as 3 groups of interconnected osseous struts that are oriented in the horizontal, sagittal and coronal planes. Each group of struts is closely related to specific soft tissue structures that are susceptible to injury. Any single CT section in the coronal plane or in the axial plane contains parts of one or more these struts. Facial CT in biplane were performed in 32 patients of facial trauma. The most common site of facial fractures is found in middle part of horizontal struts, geometrically in anteromedial portion of the inferior orbital fissure of the face. The most common soft tissue injury combined with facial fracture is hematoma and/or herniated orbital contents into the maxillary sinus. The serious combined soft tissue injuries were ocular rupture, retroorbital hematoma and optic nerve injury ...

1988-02-15

46

Sonography and Computed Tomography in the evaluation of giant Baker's cysts

Twenty-seven patients with symptoms or clinical findings suggesting joint or bone disorders of the anterior chest wall (ACW) were evaluated by spiral CT with 3-dimensional (3-D) and multiplanar reconstructions. Preceding conventional ACW tomography was performed in 10 patients. ACW joint and bone changes were visualized more adequately by coronal 2-D reconstructions based on spiral CT than by conventional tomography. In addition, nonossified costal cartilages and soft tissue lesions were demonstrated. 3-D reconstructions sometimes added information, especially in patients with fracture and dislocation. (orig.).

1994-09-01

47

MR findings in cases of suspected impacted fracture of the femoral neck

The US study of the posterior compartment of the knee usually allows the clinical suspicion of popliteal cyst to be confirmed. Neverthless, in case of giant Baker's cysts - which are, at any rate, less frequent -US diagnosis is more difficult. CT can help determine the benign nature of the lesion, and hallow an accurate spatial evaluation. Moreover CT, when accurately performed, demonstrates the caudal or cranial cystic spread, together with its clear separation from adjacent muscular tissues. Direct coronal scans are more useful to obtain better spatial definition than reformatted images.

1991-01-01

48

X-ray Emission as a Probe of the Wind-Driven Shock in WR 140

Purpose: To evaluate MR imaging of the hip in patients with a clinically suspected impacted fracture of the femoral neck in cases where conventional plain films show negative or equivocal findings. Material and Methods: Twenty-seven such patients were prospectively examined by MR imaging with a 1.0 T unit, within 24 hours of admittance to hospital. A coronal T1-weighted turbo spin-echo sequence (n=27), and a coronal STIR sequence (n=25) or a coronal T2-weighted turbo spin-echo fast saturation sequence (n=2) were used. The evaluations were made by 2 radiologists with experience in musculoskeletal radiology. Results: There were 6 patients with a petrochanteric fracture, 2 without and 4 with slight displacement. Five patients had an impacted fracture of the femoral neck, and 3 had a fracture of the superior pubic bone. Of 2 patients with advanced arthrosis, i had an impacted femoral neck fracture and the other a nondisplaced ...

1997-09-01

49

Spatiotemporal Evolution of the fMRI Response to Ultrashort Stimuli

single star evolution. To understand the evolution of massive stars and their role in shaping the galaxy, understanding of the distribution of ...

50

On Optically Thick Condensations in Planetary Nebulae NASA, Goddard

The specificity of the hemodynamic response function (HRF) is determined spatially by the vascular architecture and temporally by the evolution of hemodynamic changes. The stimulus duration...Full Text Available

2011-01-26

51

NASA Research Announcement: GALEX GI Program Cycle 2 - GALEX - NASA

effect of central star evolution would be to produce a thinner boundary, but the results of ... indicate that central star evolution may be neglected when ...

52

NASA Research Announcement: GALEX GI Program Cycle 1 - GALEX - NASA

These include, but are not limited to: stellar winds and outflows, post-main- sequence stellar evolution, binary/multiple star evolution, globular cluster ...

53

Human-modified ecosystems and future evolution

These include, but are not limited to: stellar winds and outflows, post-main- sequence star evolution, binary star evolution, globular cluster structure and ...

54

Genomic view of the evolution of the complement system

Our global impact is finally receiving the scientific attention it deserves. The outcome will largely determine the future course of evolution. Human-modified ecosystems are shaped by our activities...Full Text Available

2001-05-08

55

An Input to the UVOIR Panel Of the AASC April ... - PlanetQuest - NASA

The recent accumulation of genomic information of many representative animals has made it possible to trace the evolution of the complement system based on the presence or absence of each complement...Full Text Available

2006-09-01

56

Solar-Geophysical Data Number 438, February 1981. Part 1 (prompt reports). Data for January 1981, December 1980 and late data

Binary Star Evolution. The evolution of close binary stars can be very different from that of wide binaries of isolated stars. If the stars are close enough ...

57

New procedures. Comprehensive staging of lung cancer by MRI

Contents include: index for 1970-1980; January 1981 data -- alert periods, daily solar indices, solar flares, solar radio emission, coronal holes, inferred interplanetary magnetic field polarities, mean solar magnetic field, spacecraft observations, December 1980 data -- daily solar-activity centers, sudden ionospheric disturbances, spacecraft observations, solar radio emission, cosmic rays, geomagnetic indices, radio-propagation indices; late data -- solar radio emission November, December 1980, spacecraft observations November 1980, cosmic rays, Huancayo Oct 1980 -- climax, alert, Deep River Nov 1980.

1981-02-01

58

The beginning of a new science

Lung cancer staging according to the TNM system is based on morphological assessment of the primary cancer, lymph nodes and metastases. All aspects of this important oncological classification are measurable with MRI. Pulmonary nodules can be detected at the clinically relevant size of 4-5 mm in diameter. The extent of mediastinal, hilar and supraclavicular lymph node affection can be assessed at the same time. The predominant metastatic spread to the adrenal glands and spine can be detected in coronal orientation during dedicated MRI of the lungs. Search focused whole body MRI completes the staging. Various additional MR imaging techniques provide further functional and clinically relevant information during a single examination. In the oncological context the most important techniques are imaging of perfusion and tumor motion. Functional MRI of the lungs complements the pure staging and improves surgical approaches and radiotherapy planning. (orig.)

2010-08-01

59

Surface brightness, galaxy evolution and cosmology

The evolution of the study of extra-terrestrial neutrinos over the 45 years since their discovery.

60

Probing Neutron Star Evolution with Gamma Rays

The Thomsen and Frandsen (1983) cosmological test employing the observed correlation between elliptical galaxy surface brightness and scale size in order to avoid problems due to dynamical evolution is presently extended to make use of arbitrary galaxy samples. The explicit dependence on stellar evolution is also demonstrated. On the assumption that this evolution is calculable, an equation for the deceleration parameter entirely in terms of observables is derived. The test is applied to two available samples. 25 references.

1985-01-01

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Neutrino processes and pair formation in massive stars and supernovae.

The research sponsored by this grant was conducted in two fields of high-energy astrophysics:

1996-01-01

62

Neutrino processes role in star evolution and onset of supernovae explosion

1964-01-01

63

Life of the stars

Isopod Systematics and Evolution

Stars and star evolution are discussed, including supernovae, nucleosynthesis, and mass-luminosity and Hertzsprung--Russell diagrams./aip/.

1988-09-20

64

... inferences. Thatcher carries the banner for studies of isopod parasites of fishes of the Amazonian region. This fauna ... ...

65

Helical CT defecography

MONTE CARLO SIMULATIONS OF GLOBULAR CLUSTER EVOLUTION. V. BINARY STELLAR EVOLUTION

The purpose of this work is to investigate the possible role of Helical CT defecography in pelvic floor disorders by comparing the results of the investigations with those of conventional defecography. The series analyzed consisted of 90 patients, namely 62 women and 28 men, ranging in age 24-82 years. They were all submitted to conventional defecography, and 18 questionable cases were also studied with Helical CT defecography. The conventional examination was performed during the 4 standard phases of resting, squeezing, Valsalva and straining; it is used a remote-control unit. The parameters for Helical CT defecography were: 5 mm beam collimation, pitch 2, 120 KV, 250 m As and 18-20 degrees gantry inclination to acquire coronal images of the pelvic floor. The rectal ampulla was distended with a bolus of 300 mL nonionic iodinated contrast agent (dilution: 3g/cc). The patient wore a napkin and was seated on the table, except for those who could not hold the position ...

1999-11-01

66

Star-formation triggers and chemical evolution

We study the dynamical evolution of globular clusters containing primordial binaries, including full single and binary stellar evolution using our Monte Carlo cluster evolution code updated with an adaptation of the single and binary stellar evolution codes SSE and BSE from Hurley et al. We describe the modifications that we have made to the code. We present several test calculations and comparisons with existing studies to illustrate the validity of the code. We show that our code finds very good agreement with direct N-body simulations including primordial binaries and stellar evolution. We find significant differences in the evolution of the global properties of the simulated clusters using stellar evolution compared with simulations without any stellar evolution. In particular, we find that the mass loss from the ...

2010-08-10

67

Origins, evolution, and phenotypic impact of new genes

Comparative studies of flocculent and grand-design spirals suggest that density waves are not the predominant trigger of star formation in most galaxies. Implications for chemical evolution are profound. It may be possible to ignore the details of the spiral-wave phenomenon in research aimed at unifying the chemical properties of spiral disks. 16 references.

1986-10-01

68

On Being the Right Size: The Impact of Population Size and Stochastic Effects on the Evolution of Drug Resistance in Hospitals and the Community

Ever since the pre-molecular era, the birth of new genes with novel functions has been considered to be a major contributor to adaptive evolutionary innovation. Here, I review the origin and evolution...Full Text Available

2010-10-01

69

Neutron stars in massive binary systems. I. Classification and evolution

The evolution of drug resistant bacteria is a severe public health problem, both in hospitals and in the community. Currently, some countries aim at concentrating highly specialized services in large...Full Text Available

2011-04-01

70

Neutron Star Evolution with Internal Energy h'q/>a Dissipation by ...

A study of the joint evolution of the normal- and neutron-star components of massive binaries opens with a classification scheme and the analytic expressions to be applied in Paper II for computer simulation of the observable properties of such systems.

1983-03-01

71

Genomic Evidence for the Evolution of Streptococcus equi: Host Restriction, Increased Virulence, and Genetic Exchange with Human Pathogens

Neutron Star Evolution with Internal Energy h'q/>a. Dissipation by Vortex Creep. N. Shibazaki and F. K. Lamb. University of Illinois at Urbana-Champaign ...

72

Formation and evolution of the protoplanetary disk

The continued evolution of bacterial pathogens has major implications for both human and animal disease, but the exchange of genetic material between host-restricted pathogens is rarely considered....Full Text Available

2009-03-01

73

Evolution of the nuclear ribosomal DNA intergenic spacer in four species of the Daphnia pulex complex

A disk formation model during collapse of the protosolar nebula, yielding a low-mass protoplanetary disk is presented. The following subject areas are covered: (1) circumstellar disks; (2) conditions for the formation of stars with disks; (3) early evolution of the protoplanetary disk; and (4) temperature conditions and the convection in the protoplanetary disk.

1989-01-02

74

Evolution of macromolecular import pathways in mitochondria, hydrogenosomes and mitosomes

BackgroundConcerted evolution refers to the pattern in which copies of multigene families show high intraspecific sequence homogeneity but high interspecific sequence diversity....Full Text Available

75

Evolution of Nitrogen Oxide(s) during In Vivo Nitrate Reductase Assay of Soybean Leaves

All eukaryotes require mitochondria for survival and growth. The origin of mitochondria can be traced down to a single endosymbiotic event between two probably prokaryotic organisms. Subsequent evolution...Full Text Available

2010-03-12

76

Components of change in the evolution of learning and unlearned preference

Studies were conducted to quantitate the evolution of nitrogen oxides (NO_(x)) from soybean [Glycine max (L.) Merr.] leaves during in vivo nitrate reductase...Full Text Available

1981-12-01

77

Adaptations to sexual selection and sexual conflict: insights from experimental evolution and artificial selection

Several phenomena in animal learning seem to call for evolutionary explanations, such as patterns of what animals learn and do not learn. While several models consider how evolution should influence...Full Text Available

2009-09-07

78

A MODEL OF THE SPECTRAL EVOLUTION OF PULSAR WIND NEBULAE

Artificial selection and experimental evolution document natural selection under controlled conditions. Collectively, these techniques are continuing to provide fresh and important insights into the...Full Text Available

2010-08-27

79

White dwarf evolution - Cradle-to-grave constraints via pulsation

We study the spectral evolution of pulsar wind nebulae (PWNe) taking into account the energy injected when they are young. We model the evolution of the magnetic field inside a uniformly expanding PWN. Considering time-dependent injection from the pulsar and coolings by radiative and adiabatic losses, we solve the evolution of the particle distribution function. The model is calibrated by fitting the calculated spectrum to the observations of the Crab Nebula at an age of a thousand years. The spectral evolution of the Crab Nebula in our model shows that the flux ratio of TeV #gamma#-rays to X-rays increases with time, which implies that old PWNe are faint in X-rays, but not in TeV #gamma#-rays. The increase of this ratio is because the magnetic field decreases with time and is not because the X-ray emitting particles are cooled more rapidly than the TeV #gamma#-ray emitting particles. Our spectral ...

2010-06-01

80

Unveiling the underlying nature of the new class of HMXBs ...

White dwarf evolution, particularly in the early phases, is not very strongly constrained by observation. Fortunately, white dwarfs undergo nonradial pulsation in three distinct regions of the H-R diagram. These pulsations provide accurate masses, surface compositional structure and rotation velocities, and help constrain other important physical properties. We demonstrate the application of the tools of stellar seismology to white dwarf evolution using the hot white dwarf star PG 1159-035 and the cool DAV (or ZZ Ceti) stars as examples. From pulsation studies, significant challenges to the theory of white dwarf evolution emerge. 44 refs.

1990-05-28

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81

Single and binary star evolution

Understanding the detailed mechanics of these systems and their place in the general picture of binary star evolution are the dual objectives of this ...

82

Scientific reference on the long time evolution of spent fuels; Referentiel scientifique sur l'evolution a long terme des combustibles uses

After presenting a general account of the observed global properties of single stars of low, intermediate, and high mass, together with their theoretical Hertzsprung-Russell diagram evolution, attention is given to the observed properties of various evolved close binaries and to an assessment of the value of comparisons between observation and crude theory in characterizing the physics of mass transfer within interacting binary systems. Detailed consideration is then undertaken of such topics as stellar evolution in globular clusters, interior star changes due to nucleosynthesis and mixing, asymptotic giant branch stars of intermediate mass, the response of white dwarfs in binary systems to mass accretion, and scenarios for binary star evolution tending toward close white dwarf pairs.

83

RXTE Catches Morphing Magnetar

This report is published in the framework of the 1991 French law for the nuclear waste management. The state of the art reported here concerns the long term evolution of spent fuel in the various environmental conditions corresponding to dry storage and geological disposal: closed system, air and water saturated medium. This review is based on the results of the french PRECCI project (Research Program on Long term Evolution of Spent Nuclear Fuel) and on literature data. (authors)

2005-03-15

84

This exciting new development in neutron star evolution was presented at the Winter 2004 AAS Meeting in Atlantia,Georgia. ...

85

Nuclear astrophysics

Neutron star evolution with internal heating

Four topics in nuclear astrophysics, namely; pulsars, star evolution, nucleosynthesis and solar neutrinos are reviewed through the discussion of the observational data.

1982-09-01

86

Macular Pigment Density Evolution in Unilateral Wet AMD Versus Non AMD Patients With or Without Lutein and Zeaxanthine Supplementation

The thermal evolution predicted by current models of the superfluid-crust interaction is noted to differ substantially from the thermal evolution predicted by models without internal heating as well as previous models of heating. Heating rates approaching the maximum predicted by current models enhance the photon luminosity of the star in the neutrino cooling era, and dramatically alter the thermal evolution in the photon cooling era. Standard cooling models are consistent with current pulsar temperature estimates and upper limits, except those for the Vela pulsar, which are lower than predicted. 77 refs.

1989-11-01

87

Integration of Optimality, Neural Networks, and Physiology for Field Studies of the Evolution of Visually-elicited Escape Behaviors of Orthoptera: A Minireview and Prospects

Exudative Age-related Macular Degeneration

2011-08-03

88

KoreaScience (Korea)

Full Text Available

2008-05-01

89

CHAM_CLOUD_3 - HEASARC

Achieving the Goals and Objectives of the 2008 - Astrobiology - NASA

Main purpose of mapping observations of the cloud is to make clear the mechanism of star formation and star evolution. Scientific objectives are summarized ...

90

Formation and Evolution of Bulges

... the cinder-like planets in orbit around pulsars, the remnants of massive star evolution) to worlds that are more reassuringly familiar. ...

91

Delta Scuti stars and stellar evolution

After presenting three ways of defining a bulge component in disc galaxies, we introduce the various types of bulges, namely the classical bulges, the boxy/peanut bulges and the disc-like bulges. We then discuss three specific topics linked to bulge formation and evolution, namely the coupled time evolution of the bar, buckling and peanut strengths; the effect of velocity anisotropy on peanut formation; and bulge formation via bar destruction.

2007-01-01

92

Magnetic resonance imaging of the hip with a pelvic phased-array surface coil: a technical note

Recent developments in the knowledge of Delta Scuti stars in relation to stellar evolution are reviewed. The stability of periods and amplitudes is examined, and a working hypothesis suggested. Furthermore, the systematics of the observed long-term period changes are compared with the computed evolutionary tracks, suggesting a severe disagreement for the evolved stars if the period changes are caused by radius changes resulting from stellar evolution. 30 refs.

1990-05-28

93

MRT of the abdomen in combination with enteroclysis in Crohn disease with oral and intravenous Gd-DTPA

Objective. The aim of this study was to assess the capability of high-resolution images obtained with a commercially available pelvic phased-array surface coil to demonstrate normal hip anatomy. Design. We retrospectively analyzed the oblique coronal magnetic resonance (MR) images of hips of 36 consecutive patients acquired on a 1.5-T clinical imager using a pelvic phased-array coil as a receiver, a 16-20 cm field of view, and 5 mm slice thickness. Patients. Thirty-six patients were studied, age 15-81 years. There were 20 males and 16 females. Results and conclusions. The articular cartilage, cortex, superior labrum, and iliofemoral ligament were well visualized on proton density weighted fat saturation (PDF) images. The femoral and obturator vessels, obturator nerve, and various muscles were easily seen on T1-weighted images. High-resolution imaging of the hip is achievable in a reasonable amount of time using newer phased-array surface coils and may play an ...

1998-02-01

94

Line intensity enhancements in stellar coronal X-ray spectra due to opacity effects

60 patients between 17 and 72 years of age were investigated. First, an enteroclysis was performed in typical manner. The applicated methylcellulosis was blended with positive oral MR contrast media (Magnevist oral, Schering). After enteroclysis, MRI of the abdomen was performed using T1- and T2-weighted breathhold sequences (Flash 2D pre- and postcontrast and TSE) in axial and coronal planes. The length of the affected bowel and the stenosis seen with enteroclysis correlated well with the visible thickening of the small bowel wall and the stenosis seen in MRI. Using MRI, additional findings could be obtained in 28 patients, such as fistulas, abscesses or a hydronephrosis, or a better assessment of the stenosis was possible with MRI, because of the avoidance of overshadowing of the affected bowel loop with MRI. A brilliant MR-tomographic imaging of the small bowel is possible under the condition, that the small bowel contrast is optimal. The main prerequisite is a ...

95

Energetic electrons in impulsive and extended solar flares as deduced from flux correlations between hard X-rays and microwaves

Context. The I(15.01 A)/I(16.78 A) emission line intensity ratio in Fe XVII has been reported to deviate from its theoretical value in solar and stellar X-ray spectra. This is attributed to opacity in the 15.01 A line, leading to a reduction in its intensity, and was interpreted in terms of a geometry in which the emitters and absorbers are spatially distinct. Aims. We study the I(15.01 A)/I(16.78 A) intensity ratio for the active cool dwarf EV Lac, in both flare and quiescent spectra. Methods. The observations were obtained with the Reflection Grating Spectrometer on the XMM-Newton satellite. The emission measure distribution versus temperature reconstruction technique is used for our analysis. Results. We find that the 15.01 A line exhibits a significant enhancement in intensity over the optically thin value. To our knowledge, this is the first time that such an enhancement has been detected on such a sound statistical basis. We interpret this enhancement in terms of a geometry in ...

2008-01-01

96

Dura thickening adjacent to intracranial tumors on MRI. Histologically correlation

The peak flux relationship between hard X-rays and microwaves from solar flares is studied using about 400 events simultaneously recorded with the hard X-ray burst spectrometer on the SMM satellite and the Nobeyama 17 GHz radiometer. The data indicate that the hard X-ray and microwave peak fluxes correlate best for X-ray energies of less than about 80 keV for impulsive flares and greater than about 360 keV for extended flares. By postulating that electrons responsible for microwave emission at 17 GHz are those emitting hard X-rays at these photon energies, it is concluded that: (1) in impulsive flares, microwaves at about 20 GHz are emitted mainly by electrons of less than about 200 keV from a layer through which the electrons stream down into the thick-target hard X-ray source; and (2) in extended flares, microwaves are emitted mainly by MeV electrons trapped in a coronal loop or loops. 59 references.

1988-01-01

97

Brain development during the first year of life. Quantitative assessment with ADC imaging

Purpose: With intracranial tumors a flat, contrast-enhancing, probably dural structure adjacent to the tumor can occasionally be observed on gadolinium-DTPA enhanced MR images. Therefore we have attempted to evaluate a tumor infiltration of this enthancement on MRI. Material and Methods: This study included 50 patients. 19 patients had a dural thickening at the tumor base (13 meningiomas and 6 metastases), while 31 patients did not (12 meningiomas and 19 metastases). Studies included plane T_2-weighted spin echo (SE) images as well as T_1-weighted axial, coronal, or sagittal plains with and without contrast agent. Histopathological examinations, were done on the tumor base adjacent to the dura mater. Results: 7 of 12 meningiomas showed a meningeal thickening on MRI with histopathologically proven tumor infiltration as did also 5 of 6 metastases. But 3 of 12 meningiomas and 15 of 19 metastases without dural thickening at the tumor base also showed tumor invasion ...

98

Nuclear reaction rates and opacity in massive star evolution calculations

Brain development during the first year of life was assessed quantitatively using apparent diffusion coefficient (ADC) images constructed from diffusion-weighted MR image data. The imaging plane was coronal at the section of the pons. The cerebral peduncle, internal capsule, corona radiata, superior longitudinal fasciculus and thalamus were selected for evaluation of their ADC values. A diffusion sensitive gradient was added in the anteroposterior direction. Thus the orientation of nerve fibers in the cerebral peduncle, internal capsule and corona radiata was perpendicular to it, and that in the superior longitudinal fasciculus was parallel to it. In neonates, the cerebral peduncle and internal capsule, having been moderately myelinated at birth, showed the slowest diffusion. The corona radiata and superior longitudinal fasciculus, having been unmyelinated at birth, showed the fastest diffusion. The thalamus had intermediate diffusion. These neonatal diffusions ...

99

Effective Population Size Is Positively Correlated with Levels of Adaptive Divergence among Annual Sunflowers

Nuclear reaction rates and opacity are important parameters in stellar evolution. The input physics in a stellar evolution code determines the main theoretical characteristics of the stellar structure, evolution and nucleosynthesis of a star. For different input physics, in this work we calculate stellar evolution models of very massive first stars during the hydrogen and helium burning phases. We have considered 100 and 200M_sun galactic and pregalactic stars with metallicity Z = 10"-"6 and 10"9, respectively. The results show important differences from old to new formulations for the opacity and nuclear reaction rates, in particular the evolutionary tracks are significantly affected, that indicates the importance of using up to date and reliable input physics. The triple alpha reaction activates sooner for pregalactic than for galactic stars.

2010-07-01

100

British Library Electronic Table of Contents (United Kingdom)

The role of adaptation in the divergence of lineages has long been a central question in evolutionary biology, and as multilocus sequence data sets have become available for a wide range of taxa, empirical estimates of levels of adaptive molecular evolution are increasingly common. Estimates vary widely among taxa, with high levels of adaptive evolution in Drosophila, bacteria, and viruses but very little evidence of widespread adaptive evolution in hominids. Although estimates in plants are more limited, some recent work has suggested that rates of adaptive evolution in a range of plant taxa are surprisingly low and that there is little association between adaptive evolution and effective population size in contrast to patterns seen in other taxa. Here, we analyze data from 35 loci for si...

2011-01-01

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101

The edge of neutral evolution in social dilemmas

Measurement of Turbulence Decorrelation during Transport Barrier Evolution in a High Temperature Fusion Plasma

The functioning of animal as well as human societies fundamentally relies on cooperation. Yet, defection is often favorable for the selfish individual, and social dilemmas arise. Selection by individuals' fitness, usually the basic driving force of evolution, quickly eliminates cooperators. However, evolution is also governed by fluctuations that can be of greater importance than fitness differences, and can render evolution effectively neutral. Here, we investigate the effects of selection versus fluctuations in social dilemmas. By studying the mean extinction times of cooperators and defectors, a variable sensitive to fluctuations, we are able to identify and quantify an emerging 'edge of neutral evolution' that delineates regimes of neutral and Darwinian evolution. Our results reveal that cooperation is significantly maintained in the neutral regimes. ...

2009-09-15

102

Evolution of the primary components of massive binary stars in the case of Roche lobe overflow after main-sequence evolution

A low power polychromatic beam of microwaves is used to diagnose the behavior of turbulent fluctuations in the core of the JT-60U tokamak during the evolution of the internal transport barrier. A continuous reduction in the size of turbulent structures is observed concomitant with the reduction of the density scale length during the evolution of the internal transport barrier. The density correlation length decreases to the order of the ion gyroradius, in contrast to the much longer scale lengths observed earlier in the discharge, while the density fluctuation level remain similar to the level before transport barrier formation.

2005-03-29

103

Evolution of a vacuum shell in the Friedmann-Schwarzschild world

The components with masses 32 and 64M _s_u_n, evolved with the matter mixing in the semiconvective zone and filling their Roche lobes, after the main-sequence evolution overflow their Roche lobes and lose matter during the first part of the helium core burning. After the overflow end, the components lose the matter by stellar wind. The components shrink in the nuclear timescale. At first, they have the blue supergiant character with anomalous CNO abundance, then - the Wolf-Rayet stars character.

104

Viewing the Constellations with Binoculars

The method of an effective potential is used to investigate the possible types of evolution of vacuum shells in the Friedmann-Schwarzschild world. Such shells are assumed to emerge during phase transitions in the early Universe. The possible global geometries are constructed for the Friedmann-Schwarzschild worlds. Approximate solutions to the equation of motion of a vacuum shell have been found. The conditions under which the end result of the evolution of the vacuum shells under consideration is the formation of black holes and wormholes with baby universes inside have been found. The interior of this world can be a closed, flat, or open Friedmann universe.

2008-08-01

105

Towards a Synthetic Chloroplast

A guide to practical astronomy. It introduces the reader to some basic (and some not-so-basic) astronomical concepts, and discusses the stars and their evolution, the planets, nebulae, and distant galaxies

2010-01-01

106

The influence of EU policies on the evolution on coastal zones (Themati\\\\\\rc Study 'E')

BackgroundThe evolution of eukaryotic cells is widely agreed to have proceeded through a series of endosymbiotic events between larger cells and proteobacteria or cyanobacteria,...Full Text Available

107

TEST PLANNING APPROACH AND LESSONS. - NASA Technical Report Server ...

decline is due to EC measures introduced to control milk production (milk quotas, reduction in herd

108

TAIL FLIP AND ESCAPE RESPONSE OF TETHYSBAENA ARGENTARII (MALACOSTRACA: THERMOSBAENACEA)

requirements) + f3(accuracy of analyses) + f4(accuracy of fabrication) + f5( design time) + .... Learning curves suggest an evolution in rocket engines& ...

109

Stars, their evolution and their stability

... A. Ferrero. 2000. Escape behaviour in the stomatopod crustacean Squilla mantis, and the evolution of the caridoid escape reaction. ... ...

110

SIM: Stellar Astrophysics - SIM - NASA

The Nobel lecture of Chandrasekhar is printed in which he describes the basic processes that determine the life history of a star with particular emphasis on the roles of stellar mass and radiation pressure. (AIP)

1984-04-01

111

... and one near-main-sequence star, which will stringently constrain calculations of single-star evolution at high metallicity. Independent of SIM Lite observations ...

112

Reference List-W

RXTE GOF: News Archive 2004 - HEASARC - NASA

A SCENARIO FOR CARBON STAR EVOLUTION WILLEMS, F., DE JONG, T. 213> 821111 INFRARED OBSERVATIONS OF OH/IR STARS WILLIAMS, D. M., BOYLE, ...

113

ROSAT Status 130: Update on Wurzburg Conference - HEASARC - NASA

May 18, 2007 ... This exciting new development in neutron star evolution was presented at the Winter 2004 AAS Meeting in Atlanta, Georgia. ...

114

Quantitative Spectroscopy of Photospheric-Phase Type II SN

Aug 21, 1995... F.D. Two Southern Supernova Remnants Shibazaki, N. Effect of a Superfluid- Crust Coupling on the Neutron Star Evolution Siddiqui, ...

115

Pulsational instability in massive stars: implications for ...

... and high-quality photospheric-phase Type II SN spectra to constrain core- collapse SN explosions, massive star evolution, and distances in the Universe ...

116

Protoplanetary Disks of Binary Systems in Orion

sive star evolution based on our new calculations of this pulsational instability, where the initial mass of SNe progenitors increases according to the ...

117

Printed product downloads - NASA Space Place

Dusty primordial disks surrounding young low-mass stars are revealing tracers of stellar and planetary formation. The evolution and lifetime of these disks define the boundary conditions of the mechanisms of planet formation. Stellar companions, however, can significantly change this evolution through their tidal interactions. Stellar evolution and planet formation in binaries have to respond to an environment of truncated, quickly disappearing disks--very different compared to an isolated star environment. In order to investigate details of the influence of binarity on circumstellar disk evolution, we obtained adaptive optics supported near-infrared imaging and spectroscopy of the individual components of 22 low-mass binaries in the well-known Orion Nebula Cluster. Brackett gamma emission, which we detect in several systems, is used as a tracer for the presence of an active accretion disk around each ...

2010-01-01

118

Prestin and high frequency hearing in mammals

Aug 26, 2011 ... The main article on the back of the poster explains star evolution in very simple terms (including the fate of our own Sun), and how a planetary ...

119

Planet Forming Protostellar Disks - NASA Technical Report Server ...

Recent evidence indicates that the evolution of ultrasonic hearing in echolocating bats and cetaceans has involved adaptive amino acid replacements in the cochlear gene prestin. A substantial...Full Text Available

2011-03-01

120

Phylogenomic analyses of malaria parasites and evolution of their exported proteins

terms of 11) numerical models, 2D SPH simulations, and analytic models. The 1D model was useful for determining the evolution over very long timescales. ...

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Particle-Gas Dynamics and Primary Accretion - Space Science and ...

BackgroundPlasmodium falciparum is the most malignant agent of human malaria. It belongs to the taxon Laverania, which includes other ape-infecting Plasmodium...Full Text Available

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the revealed stage of T Tauri star evolution, is only a mere shadow of its former self. Once primary accretion starts, one has the (poorly quantified) ...

123

PPT - AstroGravS - NASA

ON THE BINDING ENERGY PARAMETER #lambda# OF COMMON ENVELOPE EVOLUTION

Form as the end result of massive star evolution; Type II supernova: collapse of iron core in highly evolved massive star; outer regions blasted away in ...

124

New Frontiers in Binary Stars: Science at High Angular ...

The binding energy parameter #lambda# plays an important role in common envelope evolution. Previous works have already pointed out that #lambda# varies throughout the stellar evolution, though it has been adopted as a constant in most of the population synthesis calculations. We have systematically calculated the binding energy parameter #lambda# for both Population I and Population II stars of masses 1-20 M _s_u_n, taking into account the contribution from the internal energy of stellar matter. We present fitting formulae for #lambda# that can be incorporated into future population synthesis investigations. We also briefly discuss the possible applications of the results in binary evolutions.

2010-06-10

125

... interacting systems in which common-envelope evolutionary effects make it hard to generalize the results to single-star evolution, although they ...

2011-05-15

126

NRAO: Press Releases

NASA Direct! - Kennedy Space Center - Home - NASA

Evolution in Space Radio Telescopes Reveal Youngest Stellar Corpse Gas Clouds in Whirlpool Galaxy Yield Important Clues Supporting Theory on Spiral Arms Starbust-driven Winds...

2011-10-09

127

Irregularities in Ionospheric Plasma Clouds: Their Evolution ...

Aug 21, 2003 ... Her research interests have included hot stars, colliding stellar winds, binary star evolution and evolved stellar companions. ...

128

Introduction & Overview to Symposium 240: Binary Stars as ...

... follows draws on Wittwer (1980b & c), Zinn et al. (1966) and Hess (1968). ... for the Starfish event) and much larger distances along the geomagnetic ...

1980-09-01

129

High Energy Astrophysics Picture Of the Week - HEASARC - NASA

... CVn) consisting of a dM3 star and a cool white dwarf that must have evolved through the common-envelope stage of binary star evolution (Else van ...

2011-05-14

130

Grain mantles: The impact on grain evolution and selective extinction

Jun 28, 2010 ... Ultracompact binaries represent the end product of a binary star evolution, and are important test cases of theories of extreme gravity. Perhaps ...

131

General Disclaimer One or more of the Following Statements may ...

Depletion studies are used to infer the presence of mantles and to constrain grain evolutionary models in the diffuse interstellar medium. The presence of these mantles appears to be important in the evolution of the grains inside diffuse as well as dense clouds. In dense clouds where the element-to-element abundances sometimes differ from those found in diffuse clouds, empirical relationships are starting to emerge between gas abundances and various types of peculiar selective extinction. These peculiar extinction curves may be the results of nonvolatile mantle formation on grain cores or may reflect chemical differences due to variations in the intrinsic metalicity from one cloud to another. A simple model of the time evolution of a parcel of gas and dust as observed by the depletion of two elements is presented. Different studies of grain evolution and selective extinction are discussed and compared.

1989-12-01

132

GLYDER - Earth Science Technology Office (ESTO) - NASA

Hie synthesis of diverse biologically important compounds, under condi- tions which existed on the earth in the initial period of its evolution, ha; ...

133

FIRST Workshop Presentation Abstract: Circumstellar Matter Around ...

goals for multisensor co-registration and fusion. 6 - 12.5 Km ..... Beta-Test toolkit for cyclogenesis and early evolution of cyclones ...

134

Experience of isolated sleep paralysis in clinical practice in Nigeria.

and the implications for massive star evolution. In recent years, the complex nature of the circumstellar regions of evolved massive stars has become apparent. ...

135

Evolution of plant senescence

The supernatural fears associated with the experience of isolated sleep paralysis in the culture of developing countries is sometimes associated with the evolution of somatic symptoms of psychological...Full Text Available

1992-06-01

136

Evolution of fruit and seed characters in the Diervilla and Lonicera clades (Caprifoliaceae, Dipsacales)

BackgroundSenescence is integral to the flowering plant life-cycle. Senescence-like processes occur also in non-angiosperm land plants, algae and photosynthetic prokaryotes. Increasing...Full Text Available

137

Dimorphic Olfactory Lobes in the Arthropoda

Background and AimsThe Diervilla and Lonicera clades are members of the family Caprifoliaceae (Dipsacales sensu Full Text Available

2009-08-01

138

Content of hydrogen, helium, and heavy elements in Procyon

Specialized olfactory lobe glomeruli relating to sexual or caste differences have been observed in at least five orders of insects, suggesting an early appearance of this trait in insect evolution....Full Text Available

2009-07-01

139

Comparing Genomes within the Species Mycobacterium tuberculosis

The values of X = 0.77, Z = 0.035, and Y = 0.195 and the stage of evolution of Procyon are determined from the evolutionary tracks and the results of an analysis of the chemical composition of the atmosphere.

1985-05-01

140

Classification of the circumstellar disc evolution during the main accretion phase

The study of genetic variability within natural populations of pathogens may provide insight into their evolution and pathogenesis. We used a Mycobacterium tuberculosis high-density...Full Text Available

2001-04-01

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141

British Library Electronic Table of Contents (United Kingdom)

Abstract We performed hydrodynamical simulations to investigate the formation and evolution of protostars and circumstellar discs from the pre-stellar cloud. As the initial state, we adopted the molecular cloud core with two non-dimensional parameters representing the thermal and rotational energies. With these parameters, we derived 17 models and calculated the cloud evolution--104 yr-after the protostar formation. We found that early evolution of the star-disc system can be qualitatively classified into four modes: the massive-disc, early-fragmentation, late-fragmentation, and protostar-dominant modes. In the -massive-disc mode-, to which the majority of models belong, the disc mass is greater than the protostellar mass for over 104 yr and no fragmentation occurs in the circumstellar dis...

2011-01-01

142

Charting the Uncharted Waters - SIM - NASA

Calibrating Cosmological Chronometers: White Dwarf Masses ...

gently constrain calculations of single-star evolution at high metallicity. Independent of SIM Lite observa- tions, we also propose to establish 4) how to ...

143

Binary stars - A look at some interesting ... - GISS Publications - NASA

... The second scenario is limited by the age of our Galaxy such that the lowest-mass WD that could be formed via single star evolution is ~0.47 M ...

2011-05-14

144

... each star goes. The results of (1) are compared with predictions based on (2) and on single star evolution theory to discover the various stages which occur. ...

145

Big bang nucleosynthesis

Astrobiology Research Priorities for Giant ... - Astrobiology - NASA

A brief review of standard big bang nucleosynthesis theory and the related observations of the light element isotopes is presented. Implications of BBN on chemical evolution and constraints on particle properties will also be discussed.

2000-01-01

146

Ancestral Genomes, Sex, and the Population Structure of Trypanosoma cruzi

Mar 6, 2009 ... remnants of massive star evolution) to worlds that are more reassuringly familiar. In the latter category, we now have excellent evidence ...

147

APOD: 2009 April 23 ... - Astronomy Picture of the Day - NASA

Acquisition of detailed knowledge of the structure and evolution of Trypanosoma cruzi populations is essential for control of Chagas disease....Full Text Available

2006-03-01

148

A Search for Core-Collapse Supernova Progenitors in Hubbk Space - NASA

Apr 23, 2009 ... Wolf-Rayet stars have over 20 times the mass of the Sun and are thought to be in a brief, pre-supernova phase of massive star evolution. ...

149

A Nearby Old Halo White Dwarf Candidate from the Sloan ...

for massive star evolution, or they could all be very blue super- giant stars experiencing A , = 1-1.5 mag. The fact that the en- ...

150

+ HUBBLE CATCHES UP WITH A BLUE STRAGGLER STAR - NASA

... than the age of the universe unless it is an unresolved double degenerate or a product of common-envelope binary star evolution (Fontaine et al. ...

2008-07-01

151

Computed Tomography of the diabetic kidney; La Tomografia Computerizzata nello studio del rene diabetico

Our analysis confirms that, but without having to make any assumptions about the state of blue straggler star evolution," Saffer said. ...

152

The evolution of x-ray binaries

The purpose of this work is to investigate whether any morphometric or densitometric are detectable in the kidneys of type 2 diabetic patients. 40 diabetic patients were examined and of 20 non-diabetics (the control group) were submitted to triphasic helical CT for different abdominal conditions. The type 2 diabetic patients were 23 men and 17 women, mean age 62 years, while the nondiabetic controls were 12 men and 8 women, mean age 58 years. All the CT images were analyzed using the Multiplanar Reconstruction (MPR) software. It was evaluated morphometric features, such as the presence of parenchymal or vascular calcifications, axial and coronal renal diameters, coronal renal area, and cortico medullary ratio, and densitometric and functional features, such as unenhanced renal density, cortical and medullary density in the arterial phase, parenchymal density in the nephrographic phase, and contrast elimination. It was also compared the results ...

2000-02-01

153

Tailored airfoils for vertical axis wind turbines

These proceedings represent papers presented at the Astrophysics Conference in Maryland, USA. The topic of the Conference was the evolution of x-ray binaries and the papers encompass a wide range of subjects on x-ray astronomy. There were one hundred eighteen papers presented at the Conference and out of these three have been abstracted for the Energy Science and Technology database.

1993-10-11

154

THE EVOLUTION OF LYMAN LIMIT ABSORPTION SYSTEMS TO REDSHIFT SIX

The evolution of a family of airfoil sections designed to be used as blade elements of a vertical axis wind turbine (VAWT) is described. This evolution consists of extensive computer simulation, wind tunnel testing and field testing. The process reveals that significant reductions in system costs-of-energy and increases in fatigue lifetime may be expected for VAWT systems using these blade elements.

1984-11-01

155

Quantitative spectroscopy of close binary stars

We have measured the redshift evolution of the density of Lyman limit systems (LLSs) in the intergalactic medium over the redshift range 0 < z < 6. We have used two new quasar samples to (1) improve coverage at z #approx# 1, with GALEX grism spectrograph observations of 50 quasars with 0.8 < z_e_m < 1.3, and (2) extend coverage to z #approx# 6, with Keck ESI spectra of 25 quasars with 4.17 < z_e_m < 5.99. Using these samples together with published data, we find that the number density of LLS per unit redshift, n(z), can be well fit by a simple evolution of the form n(z) = n_3_._5[(1 + z)/4.5]"#gamma# with n_3_._5 = 2.80 #+-# 0.33 and #gamma# = 1.94"+"0"."3"6_-_0_._3_2 for the entire range 0 < z < 6. We have also reanalyzed the evolution of damped Ly#alpha# systems (DLAs) in the redshift range 4 < z < 5 using our high-redshift quasar sample. We find a total of 17 DLAs and sub-DLAs, which we ...

2010-10-01

156

Modelling the spatial and temporal evolution of winter glacier mass balance.

The method of spectral disentangling has now created the opportunity for studying the chemical composition in previously inaccessible components of binary and multiple stars. This in turn makes it possible to trace their chemical evolution, a vital aspect in understanding the evolution of stellar systems. We review different ways to reconstruct individual spectra from eclipsing and non-eclipsing systems, and then concentrate on some recent applications to detached binaries with high-mass and intermediate-mass stars, and Algol-type mass-transfer systems.

2011-01-01

157

Environmental Research Database

DescriptionChanges in glacier mass balance are critically influenced by the distribution of snow accumulation at the start of the melt season, but models of the winter season lag seriously behind those of the melt season. The overall aim is to test physically-based models of the spatial and temporal evolution of the winter snowpack at a temperate ice cap (Langjokull, Iceland), to assess how effectively and also how efficiently they capture variation in winter accumulation. A three-step modelling approach i [continued...

2004-01-31

158

Massive Stars in the Local Group: Star Formation and Stellar Evolution

Maintenance viewpoint of a successful reactor program

The galaxies of the Local Group that are currently forming stars can serve as our laboratories for understanding star formation and the evolution of massive stars. In this talk I will summarize what I think we've learned about these topics over the past few decades of research, and briefly mention what I think needs to happen next.

2003-01-01

159

Longitudinal and transverse mode evolution in free electron laser

As the Operating and Support staffs of the FFTF organization have gained experience, the plant reliability and capacity factors have shown a steadily improving trend. The plant capacity factor for Cycle 4 was 99.5%. It is the purpose of this report to describe the evolution of the maintenance organization at the FFTF site from a general support organization to a technically proficient organization playing a major role in planning and performance of plant maintenance evolutions.

1984-06-03

160

Hydrogen evolution on Ni-P alloys. The effect of deposition conditions

We use the method of Padg approximants and Fourier transform techniques to treat analytically the problem of transverse and longitudinal mode evolution in FELs. We obtain simple relations providing a transparent understanding of the dynamic of pulse propagation effects and of transverse mode guiding. We discuss the interplay with inhomogeneous broadening effects and derive gain formulae including longitudinal and transverse mode couplings.

1995-12-31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

161

Hydrodynamic measurement of a single corrosion pit

The hydrogen evolution reaction (HER) was studied on Ni-P{sub x} electrodes containing 8 to 16 weight percent P prepared by potentiostatic deposition. The amount of P in the alloy varied with deposition potential. The activity of the electrodes was dependent on the P concentration, and the formation of a passive film. Cyclic voltametry was used to study the removal of this film. 3 refs.

1998-07-01

162

Global effects of interactions on galaxy evolution

The hydrodynamics of gas evolution plays an important role in the pitting corrosion of metals. A new technique for the measurement of the local hydrodynamics caused by corrosion processes, using the atomic force microscope, has been presented in this work. The hydrodynamics of hydrogen evolution on Al surface due to pitting corrosion was studied. The characteristic features of the hydrodynamics are discussed. To the best of our knowledge this is the first local measurement of pitting corrosion hydrodynamics.

2004-11-01

163

Gamma ray observations of the solar system

Recent observations of the evolutionary properties of paired and interacting galaxies are reviewed, with special emphasis on their global emission properties and star formation rates. Data at several wavelengths provide strong confirmation of the hypothesis, proposed originally by Larson and Tinsley, that interactions trigger global bursts of star formation in galaxies. The nature and properties of the starbursts, and their overall role in galactic evolution are also discussed.

1990-11-01

164

Galactic deuterium abundance as a test of cosmological models

Two general categories are discussed concerning the evolution of the solar system: the dualistic view, the planetesimal approach and the monistic view, the nebular hypothesis. The major points of each view are given and the models that are developed from these views are described. Possible applications of gamma ray astronomical observations to the question of the dynamic evolution of the solar system are discussed.

1981-01-01

165

Experimental research of spontaneous evolution from ultracold rydberg atoms to plasma

The problem on change of deuterium abundance in the process of galactic evolution (star evolution, supernova explosions, nucleosynthesis in supermassive objects) is considered. It is shown that the observable deuterium quantity in the interstellar medium must correspond to its cosmological abundance. This conclusion is independent of the rate of accretion of intergalactic gas by Galaxy. The effect of hypothetical pregalactic active objects on cosmological deuterium is small. It is poind out that observations of interstellar deuterium in absorbtion at lambda=91.6 cm are significant.

1982-02-01

166

Evolution of the luminosity function of quasar accretion disks

The spontaneous evolution from ultracold Rydberg atoms to plasma is investigated in a caesium MOT by using the method of field ionization. The plasma transferred from atoms in different Rydberg states (n=22-32) are obtained experimentally. Dependence of the threshold time of evolving to plasma and the threshold number of initial Rydberg atoms on the principal quantum number of initial Rydberg states is studied. The experimental results are in agreement with hot-cold Rydberg-Rydberg atom collision ionization theory. (authors)

2008-04-01

167

Evolution of a horizontal branch Population II star with total mass 0.63 Msub solar

Using an accretion-disk model, accretion disk luminosities are calculated for a grid of black hole masses and accretion rates. It is shown that, as the black-hole mass increases with time, the monochromatic luminosity at a given frequency first increases and then decreases rapidly as this frequency is crossed by the Wien cutoff. The upper limit on the monochromatic luminosity, which is characteristic for a given epoch, constrains the evolution of quasar luminosities and determines the evolultion of the quasar luminosity function. 22 refs.

168

Contribution of Gene Amplification to Evolution of Increased Antibiotic Resistance in Salmonella typhimurium

The theoretical evolution of a horizontal branch star of Population II is followed through the helium burning in the core phase and is compared with the results given by other investigators. The m- fluence of different physics and interpolation schemes in the opacity tables is discussed. Some thoughts are given on the explanation of the erratic period variations observed in some of the RR Lyrae variables in the globular clusters. (auth)

1973-01-01

169

Studies on the Evolution of Silver Nanoparticles in Micelle by UV-Photoactivation

The use of β-lactam antibiotics has led to the evolution and global spread of a variety of resistance mechanisms, including β-lactamases, a group of enzymes that degrade the β-lactam...Full Text Available

2009-08-01

170

N-body Models of Extended Clusters

Ultraviolet (UV) photoirradiation of Ag(I) compounds in the presence of an aqueous Triton X-100 solution has been exploited for the first time to prepare reproducible yellow silver hydrosol. The evolution of nanosized silver particles has been examined critically under the influence of different anions/ligands. Hence, time dependent evolution of silver hydrosol from different silver compounds in micelle via photochemical reduction is observed. Anions/ligands of precursor salts have been found to show profound influence (due to electron scavenging property, solubility, stability etc.) on the evolution route and efficiency of photochemical reduction of Ag(I) to Ag(O) in micelle and thereby classification of silver compounds becomes possible. Kinetic results reveal that the formation of silver particles proceeds via autocatalytic growth mechanism. The observed variation in rate constant values for the ...

2003-12-15

171

Formation and dynamical evolution of galaxies and of their components

We use direct N-body simulations to investigate the evolution of star clusters with large size-scales with the particular goal of understanding the so-called extended clusters observed in various Local Group galaxies, including M31 and NGC6822. The N-body models incorporate a stellar mass function, stellar evolution and the tidal field of a host galaxy. We find that extended clusters can arise naturally within a weak tidal field provided that the tidal radius is filled at the start of the evolution. Differences in the initial tidal filling-factor can produce marked differences in the subsequent evolution of clusters and the size-scales that would be observed. These differences are more marked than any produced by internal evolution processes linked to the properties of cluster binary stars or the action of an intermediate-mass black hole, based on models performed in this work and ...

2010-01-01

172

The role of high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in the diagnosis of preoperative and postoperative complications caused by acquired cholesteatomas

From this vast subject, I will pick out and review three specific topics, namely the formation and evolution of bars, the formation of bulges, and the evolution during multiple major mergers. Bars form naturally in galactic discs. Their evolution is driven by the exchange of angular momentum within the galaxy. This is emitted mainly by near-resonant material in the inner disc (bar), and is absorbed by near-resonant material in the outer disc and in the halo. As a result of this, the bar becomes stronger and rotates slower. Bulges are not a homogeneous class of objects. Based on their formation history, one can distinguish three types. Classical bulges are mainly formed before the actual disc component, from collapses or mergers and the corresponding dissipative processes. Boxy/peanut bulges are parts of bars seen edge-on. Finally, disc-like bulges are formed by the inflow of material to the center due to bar torques. Major ...

2005-01-01

173

Pituitary disease in childhood: utility of magnetic resonance; Patologia hipofisaria en la edad pediatrica: unidad de la resonance magnetica

The role of high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in the diagnosis of preoperative and postoperative complications caused by acquired cholesteatomas will be described in this paper. The pre- and postoperative imaging of the temporal bone was performed with HRCT and MRI. HRCT and MRI were performed in the axial and coronal plane. MRI was done with T2 weighted and T1 weighted sequences both before and after the intravenous application of contrast material. All imaging findings were confirmed clinically or surgically. The preoperative cholesteatoma-caused complications depicted by HRCT included bony erosions of the ossicles, scutum, facial canal in the middle ear, tympanic walls including the tegmen tympani, and of the labyrinth. The preoperative cholesteatoma-caused complications depicted by MRI included signs indicative for labyrinthitis, and brain abscess. Postoperative HRCT depicted bony erosions caused by recurrent ...

2003-03-01

174

MR imaging of regional late brain development

To assess the utility of magnetic resonance (MR) imaging in the study of pediatric patients with clinical suspicion of pituitary disease. We studied 18 patients aged 7 to 18 years.Fifteen had hormonal disturbances, two presented amenorrhea and 1 complained of headache, fever and symptoms of polyuria and polydipsia. All the patients were examined using a Siemens SP 42 1-Tesla MRI scanner. Sagittal and coronal T1-weighted spin-echo images were obtained; in addition T2-weighted spin-echo or fast spin-echo imaging was performed in ten cases and intravenous gadolinium was administered in nine. We found 9 patients with hypothalamic-pituitary dysgenesis, 2 with germinoma, 2 cases of pituitary hemosiderosis in patients with thalassemia, 2 cases of microadenoma, one abscess, one case of idiopathic central diabetes insipidus and one of Langerhans cell histiocytosis. MR enabled us to assess pituitary structural alterations in children with hypothalamic-pituitary hormone ...

2000-07-01

175

Interventional procedures in superficial lesions: the value of 2D with additional coronal reformatted 4D ultrasonography guidance

This paper reports, to complement current knowledge on brain development, late regional brain maturation assessed with quantitative MR imaging. Axial and coronal head spin-echo (SE) images were obtained in 60 healthy individuals aged 5--56 years, with a double-echo, flow compensated imaging sequence obtained with a 1.5-T Magnetom spectroscopy and imaging system. T2-weighted images were calculated from the intensity differences in SE images at echo times (TEs) of 15 and 90 msec (TR = 2.5 second). The mean T2 values were determined at 16 sites in each cerebral hemisphere. T2 values of the six frontal subcortical white matter (FSCWM) sites and of the internal capsule (IC) were evaluated. Mean T2 values in the IC decreased until age 10 years, whereas this decrease continued in the FSCWM past age 15 years before reaching a plateau. Differential age-dependent patterns of mean T2 values emerged between the six FSCWM sites. The spread of T2 values varied at different sites ...

176

Dynamical Cycles in Charge and Energy for Iron Ions Accelerated in a Hot Plasma

We wanted to assess the usefulness of four-dimensional (4D) ultrasonography (US), i.e., real-time three-dimensional US, as an adjunct for performing various US-guided interventional procedures in superficial lesion. Thirty-three patients were referred for US-guided interventional procedures for superficial lesions, including core biopsy in 19, fine- needle aspriation in eight, therapeutic drug injection in four and needle puncture in two. The procedures were performed under 4D US guidance. We reviewed the pathologic/cytologic results of the core biopsies or needle aspirations, and also the outcomes of drug injection or needle puncture. For all the patients who underwent 4D US-guided core biopsy, the specimens were adequate for making the pathological diagnosis, and specimens were successfully obtained for those patients who underwent 4D US-guided aspiration. The patients treated with 4D US-guided therapeutic drug injection or needle puncture had a good response. No major ...

2006-03-01

177

Digital atlas of fetal brain MRI

We consider a unified model of Fe ion acceleration in the solar corona. The model comprises charge-changing processes, Coulomb energy losses, and both regular and stochastic acceleration. At a given acceleration scenario, the type of acceleration is found to have a minor effect on the mean charge states, but the shapes of the charge-state distributions produced by regular acceleration and by stochastic acceleration are different. During a continual acceleration at coronal temperatures, iron ions typically follow rising trajectories on the charge-energy plane. These trajectories are situated below the mean equilibrium charge curve defined from the balance of ionization and recombination at fixed energy. During stopping, the iron ions cross the equilibrium charge curve and run through a series of charge states above the mean equilibrium charge at current energy, because the Coulomb deceleration rate significantly exceeds the rate of the ion recombination in a hot ...

2001-08-01

178

Diagnosis of occipital condyle fractures; Diagnostik von Frakturen der Okzipitalkondylen

Fetal MRI can be performed in the second and third trimesters. During this time, the fetal brain undergoes profound structural changes. Interpretation of appropriate development might require comparison with normal age-based models. Consultation of a hard-copy atlas is limited by the inability to compare multiple ages simultaneously. To provide images of normal fetal brains from weeks 18 through 37 in a digital format that can be reviewed interactively. This will facilitate recognition of abnormal brain development. T2-W images for the atlas were obtained from fetal MR studies of normal brains scanned for other indications from 2005 to 2007. Images were oriented in standard axial, coronal and sagittal projections, with laterality established by situs. Gestational age was determined by last menstrual period, earliest US measurements and sonogram performed on the same day as the MR. The software program used for viewing the atlas, written in C, permits linked ...

2010-02-01

179

INTERACTING BINARIES WITH ECCENTRIC ORBITS. III. ORBITAL EVOLUTION DUE TO DIRECT IMPACT AND SELF-ACCRETION

Following the conventional X-ray diagnosis of the skull and upper cervical spine, CT proved to be the primary diagnostic method after a skull and brain injury: For all 4 cases we succeeded in detecting the occipital condyle fracture and in determing its size and location by reconstructions (coronal, sagittal, 3-D). In the case of complex occompanying injuries like soft tissue hematomas (cerebral, in the spinal cord, and the soft tissue of the neck) or for the detection of brain stem contusion, MRT had significant advantages. MRT can offer a higher image quality in soft tissue, especially in the spinal cord and the brain. (orig.) [Deutsch] Im Anschluss an die konventionelle Roentgendiagnostik des Schaedels und der Halswirbelsaeule, erwies sich die Computertomographie als primaer einzusetzendes diagnostisches Verfahren, nach erlittenem Schaedel-Hirn-Trauma. In allen Faellen gelang der exakte Frakturnachweis an den Okzipitalkondylen, die Bestimmung des ...

1995-01-01

180

Evolution of nitrogen oxide(s) during in vivo nitrate reductase assay of soybean leaves

The rapid circularization and synchronization of the stellar components in an eccentric binary system at the onset of Roche lobe overflow is a fundamental assumption common to all binary stellar evolution and population synthesis codes, even though the validity of this assumption is questionable both theoretically and observationally. Here we calculate the evolution of the orbital elements of an eccentric binary through the direct three-body integration of a massive particle ejected through the inner Lagrangian point of the donor star at periastron. The trajectory of this particle leads to three possible outcomes: direct accretion onto the companion star within a single orbit, self-accretion back onto the donor star within a single orbit, or a quasi-periodic orbit around the companion star, possibly leading to the formation of a disk. We calculate the secular evolution of the binary orbit in the first two cases and conclude ...

2010-11-20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

181

Durability of cement-based materials: modeling of the influence of physical and chemical equilibria on the microstructure and the residual mechanical properties; Durabilite des materiaux cimentaires: modelisation de l'influence des equilibres physico-chimiques sur la microstructure et les proprietes mecaniques residuelles

Studies were conducted to quantitate the evolution of nitrogen oxides (NO/sub (x)/) from soybean (Glycine max (L.) Merr.) leaves during in vivo nitrate reductase (NR) assays with aerobic and anaerobic gas purging. Anaerobic gas purging (N/sub 2/ and argon) consistently resulted in greater NO/sub (x)/ evolution than did aerobic gas purging (air and O/sub 2/). The evolution of NO/sub (x)/ was dependent on gas flow rate and on NO/sub 2//sup -/ formation in the assay medium; although a threshold level of NO/sub 2//sup -/ appeared to exist beyond which the rate of NO/sub (x)/ evolution did not increase further. The loss of NO/sub (x)/ from in vivo NR assays under gas purging explains partially, but not stoichiometrically, the decrease of NO/sub 2//sup -/ accumulation in in vivo NR assay medium with young soybean leaves. The lack of stoichiometry between NO/sub (x)/ evolution and apparent ...

1981-12-01

182

Time reversible evolution via nonadiabatic coupling in adiabatic dark subspace

A large part of mechanical and durability characteristics of cement-based materials comes from the performances of the hydrated cement, cohesive matrix surrounding the granular skeleton. Experimental studies, in situ or in laboratory, associated to models, have notably enhanced knowledge on the cement material and led to adapted formulations to specific applications or particularly aggressive environments. Nevertheless, these models, developed for precise cases, do not permit to specifically conclude for other experimental conclusions. To extend its applicability domain, we propose a new evolutive approach, based on reactive transport expressed at the microstructure scale of the cement. In a general point of view, the evolution of the solid compounds of the cement matrix, by dissolutions or precipitations, during chemical aggressions can be related to the pore solution evolution, and this one relied to the ionic exchanges ...

2004-09-15

183

British Library Electronic Table of Contents (United Kingdom)

We propose a method for the creation of arbitrary superposition of N atomic states using generalized stimulated Raman adiabatic passage (STIRAP) techniques with laser fields coupling each one of N lower states to a single upper state in a Formula Not Shown -level atomic system. Formula Not Shown dark states that are composed of N lower states span a dark subspace. In the adiabatic limit, the dark and bright subspaces are decoupled, thus the nonadiabatic interaction within this dark subspace dominates the evolution of the system. Different from general methods to create our required coherent superposition state, in a reverse way, here we consider the required state as the starting point of evolution dynamics, and utilize laser fields to drive it into a single lower state step by step. Time ...

2010-01-01

184

The evolution of the Cepheid stars

Role of the radiation pressure gradient in giant and supergiant star evolution

The evolution of intermediate and high mass stars is reviewed focusing on the interpretation of Pop I Cepheids. First, a summary is given of the classical results of stellar evolution theory for the main evolutionary phases (main sequence and core He-burning) all over the HR diagram, putting into evidence the various points of disagreement with current observational data. Second, models incorporating the effect of convective overshoot, are reviewed, and studies are presented on the rich, young clusters in the Large Magellanic Cloud, in which the models are compared with the observational data. Arguments are given to favor the adoption of models with convective overshoot instead of the classical ones. Third, new results are presented for pulsational models of the Cepheid stars, and the shape of the instability strip in the HR diagram, the number frequency-period distribution, and the mass discrepancy are discussed. 81 refs.

1990-05-28

185

Reply to comment on "A simple model for the short-time evolution of near-surface current and temperature profiles"

Since some of the earliest evolutionary calculations it has been found that post main sequence stars become red giants (e.g. Sandage and Schwarzschild, 1952). However the exact physical processes that lead to and determine the rate of redward evolution are not completely understood. We hypothesized that the redward evolution might be due to an increase in radiation pressure somewhere in the star that causes the layers above it to be pushed outward, resulting in an expanded envelope and a cooler surface temperature. If the radiative luminosity somewhere in the star approached the Eddington limit, the outer layers would obviously expand. However, due to the presence of gas pressure, the critical value for expansion would be somewhat less than the Eddington limit.

1983-10-07

186

Renormalization Group Running of Lepton Mixing Parameters in See-Saw Models with $S_4$ Flavor Symmetry

This is our response to a comment by Walter Eifler on our paper `A simple model for the short-time evolution of near-surface current and temperature profiles' (arXiv:physics/0503186, accepted for publication in Deep-Sea Research II). Although Eifler raises genuine issues regarding our model's validity and applicability, we are nevertheless of the opinion that it is of value for the short-term evolution of the upper-ocean profiles of current and temperature. The fact that the effective eddy viscosity tends to infinity for infinite time under a steady wind stress may not be surprising. It can be interpreted as a vertical shift of the eddy viscosity profile and an increase in the size of the dominant turbulent eddies under the assumed conditions of small stratification and infinite water depth.

2005-01-01

187

Phase Information and the Evolution of Cosmological Density Perturbations

We study the renormalization group running of the tri-bimaximal mixing predicted by the two typical $S_4$ flavor models at leading order. Although the textures of the mass matrices are completely different, the evolution of neutrino mass and mixing parameters is found to display approximately the same pattern. For both normal hierarchy and inverted hierarchy spectrum, the quantum corrections to both atmospheric and reactor neutrino mixing angles are so small that can be neglected. The evolution of solar mixing angle $\\theta_{12}$ depends on $\\tan\\beta$ and mass spectrum, the deviation from its tri-bimaximal value could be large. Taking into account the renormalization group running effect, the neutrino spectrum is constrained by experimental data on $\\theta_{12}$ and the inverted hierarchy spectrum is disfavored for large $\\tan\\beta$. The evolution of light neutrino masses is approximately described by a common ...

2010-01-01

188

Nonlinear evolution of protostellar disks and light modulations in young stellar objects

The Fourier transform of cosmological density perturbations can be represented in terms of amplitudes and phases for each Fourier mode. We investigate the phase evolution of these modes using a mixture of analytical and numerical techniques. Using a toy model of one-dimensional perturbations evolving under the Zel'dovich approximation as an initial motivation, we develop a statistic that quantifies the information content of the distribution of phases. Using numerical simulations beginning with more realistic Gaussian random-phase initial conditions, we show that the information content of the phases grows from zero in the initial conditions, first slowly and then rapidly when structures become non-linear. This growth of phase information can be expressed in terms of an effective entropy: Gaussian initial conditions are a maximum entropy realisation of the initial power spectrum, gravitational evolution decreases the phase entropy. We show that ...

2000-01-01

189

Late cenozoic evolution of Fortymile Wash: Major change in drainage pattern in the Yucca Mountain, Nevada region during late miocene volcanism

An evolutionary model of dynamical processes in protostellar disks is described and illustrated with graphs of typical results. The effective transport mechanisms are discussed, including thermal convection, nonaxisymmetric gravitational instabilities in the outer regions of disks, and wave propagation. Consideration is then given to the stages of dynamical evolution, FU Ori outburst phenomena, unsteady accretion-disk flows, and nonlinear feedback as a mechanism to modulate mass transfer. The simulations show that mass redistribution is determined by angular-momentum transfer, which in turn is regulated by the effective viscosity generated by convectively driven turbulence. Significant mass transfer occurs as a result of mixing of infalling material with disk gas and is affected by the tidal torque associated with the growth of nonaxisymmetric disturbances in the outer disk. The time scale for disk evolution is found to be about 1 Myr. 72 refs.

1989-10-05

190

Influence of Population III stars on cosmic chemical evolution

The site characterization of Yucca Mountain, NV as a potential high level nuclear waste repository includes study of the surficial deposits as a record of the paleoenvironmental history of the Yucca Mountain region. An important aspect of this history is an understanding of the evolution of paleogeography leading to establishment of the present drainage pattern. Establishment of drainage basin evolution is needed before geomorphic response to paleoclimate and tectonics can be assessed, because a major change in drainage basin geometry can predominantly affect the sedimentary record. Because alluvial aquifers are significant to regional hydrology, a major change in surface drainage resulting in buried alluvium could have hydrogeologic significance. In this paper, we report on geologic evidence for a major modification in surface drainage pattern in the Yucca Mountain region, resulting in the probable establishment of the Fortymile Wash drainage ...

1994-05-22

191

British Library Electronic Table of Contents (United Kingdom)

ABSTRACT New observations from the Hubble Ultra Deep Field suggest that the star formation rate at Formula Not Shown drops off faster than previously thought. Using a newly determined star formation rate for the normal mode of Population II/I (PopII/I) stars, including this new constraint, we compute the Thomson scattering optical depth and find a result that is marginally consistent with Wilkinson Microwave Anisotropy Probe 5 results. We also reconsider the role of Population III (PopIII) stars in light of cosmological and stellar evolution constraints. While this input may be needed for reionization, we show that it is essential in order to account for cosmic chemical evolution in the early universe. We investigate the consequences of PopIII stars on the local metallicity distribution fu...

2009-01-01

192

Evolutionary implications of morphogenesis and molecular patterning of the blind gut in the planarian Schmidtea polychroa

British Library Electronic Table of Contents (United Kingdom)

The formation of a through-gut was a key innovation in the evolution of metazoans. There is still controversy regarding the origin of the anus and how it may have been either gained or lost during evolution in different bilaterian taxa. Thus, the study of groups with a blind gut is of great importance for understanding the evolution of this organ system. Here, we describe the morphogenesis and molecular patterning of the blind gut in the sexual triclad Schmidtea polychroa. We identify and analyze the expression of goosecoid, commonly associated with the foregut, and the GATA, ParaHox and T-box genes, members of which commonly are associated with gut regionalization. We show that GATA456a is expressed in the blind gut of triclads, while GATA456b is localized in dorsal parenchymal cells. Goo...

2011-01-01

193

Close binaries containing Supermassive Black Holes

British Library Electronic Table of Contents (United Kingdom)

We consider the evolution of binary systems formed by a Supermassive Black Hole (SMBH) residing in the center of a galaxy or a globular cluster and a star in its immediate vicinity. The star is assumed to fill its Roche lobe, and the SMBH accretes primarily the matter of this star. The evolution of such a system is mainly determined by the same processes as for an ordinary binary. The main differences are that the donor star is irradiated by hard radiation emitted during accretion onto the SMBH; in a detached system, nearly all the donor wind is captured by the black hole, which strongly affects the evolution of the semi-major axis; it is not possible for companions of the most massive SMBHs to fill their Roche lobes, since the corresponding orbital separations are smaller than the radius ...

2010-01-01

194

Biodiversity, agriculture, and livelihoods: Co-evolution and competition in an Andean-Amazonian watershed

Environmental Research Database

Objectives1. To create a strong, interdisciplinary evidence base about the relationships linking ecosystems, agrobiodiversity, wild biodiversity, and sustainable livelihoods, including the use of trade-off analysis (modeling the relationships between agricultural productivity, levels of biodiversity, and ecosystem resilience); crop evolutionary studies (wild relative/crop interactions) and socioeconomic, cultural, and nutritional studies of the contribution of biodiversity to different livelihoods asset [continued...]DescriptionAgriculture, ecosystems, and humans have co-evolved over millennia in the Andean-Amazonian region, creating the richest of all Vavilov centers of crop origin and diversity. The conservation of a wide range of domesticated crops and landraces (i.e., indigenous, ancestral varieties or cultivars that are distinct, uniform, and stable) and their co-evolution with crop wild relatives (CRW) has been essential for food security, adaptation to ...

2011-01-31

195

A unified framework for biological evolution and stochastic quantization

A Lamarckian Hybrid of Differential Evolution and Conjugate Gradients for Neural Network Training

We investigate the profound relation between the equations of biological evolution and quantum mechanics by writing a biologically inspired equation for the stochastic dynamics of an ensemble of particles. Interesting behavior is observed which is related to a new type of stochastic quantization. We find that the probability distribution of the ensemble of particles can be decomposed into eigenfunctions associated to a discrete spectrum of eigenvalues. In absence of interactions between the particles, the out-of-equilibrium dynamics asymptotically relaxes towards the fundamental state. This phenomenon can be related with the Fisher theorem in biology. On the contrary, in presence of scattering processes the evolution reaches a steady state in which the distribution of the ensemble of particles is characterized by a Bose-Einstein statistics. In order to show a concrete example of this stochastic quantization we have solved explicitly the case in ...

2010-01-01

196

British Library Electronic Table of Contents (United Kingdom)

The paper describes two schemes that follow the model of Lamarckian evolution and combine differential evolution (DE), which is a population-based stochastic global search method, with the local optimization algorithm of conjugate gradients (CG). In the first, each offspring is fine-tuned by CG before competing with their parents. In the other CG is used to improve both parents and offspring in a manner that is completely seamless for individuals that survive more than one generation. Experiments involved training weights of feed-forward neural networks to solve three synthetic and four real-life problems. In six out of seven cases the DE?CG hybrid, which preserves and uses information on each solution?s local optimization process, outperformed two recent variants of DE.

2010-01-01

197

X-ray stars in globular clusters

Worlds within worlds: evolution of the vertebrate gut microbiota

The properties and kinetics of x-ray stars in globular clusters are described. Locations, configurations, star evolution, massive close binary systems, various mechanisms, and the x-ray burster properties are included. (JFP)

1977-10-01

198

Underlying Principles of Natural Selection in Network Evolution: Systems Biology Approach

Here we use published 16S rRNA gene sequences to compare the bacterial assemblages associated with humans, other mammals, other metazoa, and free-living microbial communities spanning a range...Full Text Available

2008-10-01

199

Tool Life Prediction for Ceramic Tools in Intermittent Turning of Hardened Steel Based on Damage Evolution Model

Systems biology is a rapidly expanding field that integrates diverse areas of science such as physics, engineering, computer science, mathematics, and biology toward the goal of elucidating the underlying...Full Text Available

200

The mode and tempo of genome size evolution in eukaryotes

Al2O3-based ceramic is one of the most widely used materials for tools employed in hardened steel turning applications due to its high hardness, wear resistance, heat resistance and chemical stability. The objective of this work is to predict the lives of Al2O3-(W, Ti)C ceramic tools in intermittent turning of hardened AISI 1045 steel by means of damage evolution model taking into account the mechanical loading and thermal effect in the cutting process. A damage evolution model analyzing the RVE with uniformly distributed interacting cracks is constructed based on micromechanics. The calculated results of the proposed damage evolution model are compared with the lives of two kinds of Al2O3-(W, Ti)C ceramic tools obtained through experiments. It is found that the proposed model can be used to predict the lives of the ceramic cutting tools in intermittent turning operation.

2011-07-01

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201

The evolution of fossoriality and the adaptive role of horns in the Mylagaulidae (Mammalia: Rodentia)

Eukaryotic genome size varies over five orders of magnitude; however, the distribution is strongly skewed toward small values. Genome size is highly correlated to a number of phenotypic traits, suggesting...Full Text Available

2007-05-01

202

The erratic mitochondrial clock: variations of mutation rate, not population size, affect mtDNA diversity across birds and mammals

Ceratogaulus, a member of the extinct fossorial rodent clade Mylagaulidae, is the only known rodent with horns and the smallest known horned mammal. The function of the large, dorsally...Full Text Available

2005-08-22

203

The Redshift Evolution of Wet, Dry, and Mixed Galaxy Mergers from Close Galaxy Pairs in the DEEP2 Galaxy Redshift Survey

BackgroundDuring the last ten years, major advances have been made in characterizing and understanding the evolution of mitochondrial DNA, the most popular marker of molecular biodiversity....Full Text Available

204

The Medical Home Concept and Congenital Adrenal Hyperplasia: A Comfortable Habitat!

We study the redshift evolution of galaxy pair fractions and merger rates for different types of galaxies using kinematic pairs selected from the DEEP2 Redshift Survey. Parameterizing the evolution of the pair fraction as (1+z)^{m}, we find that the companion rate increases mildly with redshift with m = 0.41+-0.20 for all galaxies with -21 < M_B^{e} < -19. Blue galaxies show slightly faster evolution in the blue companion rate with m = 1.27+-0.35 while red galaxies have had fewer red companions in the past as evidenced by the negative slope m = -0.92+-0.59. We find that at low redshift the pair fraction within the red sequence exceeds that of the blue cloud, indicating a higher merger probability among red galaxies compared to that among the blue galaxies. With further assumptions on the merger time scale and the fraction of pairs that will merge, the galaxy major merger rates for 0.1 < z <1.2 are estimated to ...

2008-01-01

205

The Development and Evolution of Division of Labor and Foraging Specialization in a Social Insect (Apis mellifera L.)

Patient-centered interdisciplinary health care for children with chronic medical disorders represents an evolution from the traditional “stop and go” treatment for acute illnesses. This...Full Text Available

2010-01-01

206

Selecting Folded Proteins from a Library of Secondary Structural Elements

How does complex social behavior evolve? What are the developmental building blocks of division of labor and specialization, the hallmarks of insect societies? Studies have revealed the developmental...Full Text Available

2006-01-01

207

Sciiientttiiifffiiic apaciiittty uiiillldiiing nhancementtt fffor ustttaiiinabllle evelllopmenttt iiin evelllopiiing ountttriiies

A protein evolution strategy is described by which double-stranded DNA fragments encoding defined E. coli protein secondary structural elements (α-helices, β-strands...Full Text Available

2008-01-09

208

SN1987A: The supernova of a lifetime

Buizer, Arizona State University, USA; Gernot Klepper, Kiel Institute of World Economics, ...der Leeuw School for Human Evolution and Social Change, Arizona State University, USA

209

Reduced-Median-Network Analysis of Complete Mitochondrial DNA Coding-Region Sequences for the Major African, Asian, and European Haplogroups

The current status of cosmological observations is presented; and the light curves and radiation spectra from supernova SN1987A are used in comparison between expected and observed universal nucleosynthesis and star evolution data./aip/.

1988-09-20

210

Reciprocal Silencing, Transcriptional Bias and Functional Divergence of Homeologs in Polyploid Cotton (Gossypium)

The evolution of the human mitochondrial genome is characterized by the emergence of ethnically distinct lineages or haplogroups. Nine European, seven Asian (including Native American), and three African...Full Text Available

2002-05-01

211

Rapid evolution of sessility in an endemic species flock of the freshwater bivalve Corbicula from ancient lakes on Sulawesi, Indonesia

Polyploidy is an important force in the evolution of flowering plants. Genomic merger and doubling induce an extensive array of genomic effects, including immediate and long-term alterations in the...Full Text Available

2009-06-01

212

Rab protein evolution and the history of the eukaryotic endomembrane system

The fauna of ancient lakes frequently contains taxa with highly derived morphologies that resulted from in situ radiation of lacustrine lineages with high antiquity. We employed a molecular...Full Text Available

2006-03-22

213

Power of grammatical evolution neural networks to detect gene-gene interactions in the presence of error

Spectacular increases in the quantity of sequence data genome have facilitated major advances in eukaryotic comparative genomics. By exploiting homology with classical model organisms, this makes possible...Full Text Available

2010-10-01

214

Plasma Electric Potential Evolution at the Core and Edge of the TJ-II Stellarator and T-10 Tokamak

BackgroundWith the advent of increasingly efficient means to obtain genetic information, a great insurgence of data has resulted, leading to the need for methods for analyzing this...Full Text Available

215

Parallel Evolution of a Type IV Secretion System in Radiating Lineages of the Host-Restricted Bacterial Pathogen Bartonella

In this article are presented main results on electric potential investigations in stellarator/torsatron TJ-II and tokamak T-10 in a comparable regimes of device operation.

2006-01-01

216

Ontological realism: A methodology for coordinated evolution of scientific ontologies

Adaptive radiation is the rapid origination of multiple species from a single ancestor as the result of concurrent adaptation to disparate environments. This fundamental evolutionary process is considered...Full Text Available

2011-02-01

217

Since 2002 we have been testing and refining a methodology for ontology development that is now being used by multiple groups of researchers in different life science domains. Gary Merrill,...Full Text Available

2010-11-15

218

Observatory reports

This review covers research done at Lawrence Livermore National Laboratory under DOE contract. Areas of research are as follows: star evolution supernovae, and nucleosynthesis; stellar atmospheres and winds; galaxies and interstellar space; and high-energy astrophysics.

1983-01-01

219

Observatory report

Nucleon resonance studies in phenomenological analysis of the CLAS

This review covers research done at Lawrence Livermore National Laboratory in the fields of astronomy and astrophysics. The research areas mentioned are as follows: star evolution, supernovae, and nucleosynthesis; stellar atmospheres and winds; galaxies and the interstellar medium; and high-energy astrophysics.

1984-01-01

220

Neutron star collisions and the r-process

First comprehensive data on the evolution of nucleon resonance photocouplings with photon virtuality Q{sup 2} are presented for excited proton states in the mass range from 1.4 to 2.0 GeV.

2006-07-01

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221

Multivesicular bodies in the enigmatic amoeboflagellate Breviata anathema and the evolution of ESCRT 0

It is shown that a natural consequence of the binary pulsar's evolution is a neutron star collision. Such a collision is expected to eject neutron-rich matter of an r-process character. Taking reasonable estimates for the number of such events over the history of the galaxy, it may be that they account for all of the r-process nuclei.

1982-01-01

222

Lineage-specific co-evolution of the Egf receptor/ligand signaling system

Endosomal sorting complexes required for transport (ESCRTs) are heteromeric protein complexes required for multivesicular body (MVB) morphogenesis. ESCRTs I, II, III and III-associated are ubiquitous...Full Text Available

2011-02-15

223

BackgroundThe epidermal growth factor receptor (Egfr) with its numerous ligands has fundamental roles in development, cell differentiation and physiology. Dysfunction of the receptor-ligand...Full Text Available

224

Jane Powell

Integrase-directed recovery of functional genes from genomic libraries

...The Political Evolution of the Landfill Tax in the UK wm-1996-03 Green Taxes, Waste Management and Political Economy 1995 ^ Top ...on civil engineering Lifecycle assessment - an overlooked opportunity Refereed Journal Articles: Green taxes, waste management and political economy Reports: Environmental cost benefit ...

225

Inferring Stabilizing Mutations from Protein Phylogenies: Application to Influenza Hemagglutinin

Large population sizes, rapid growth and 3.8 billion years of evolution firmly establish microorganisms as a major source of the planet's biological and genetic diversity. However, up to 99% of the...Full Text Available

2009-09-01

226

Induction and transmission of Bacillus thuringiensis tolerance in the flour moth Ephestia kuehniella

One selection pressure shaping sequence evolution is the requirement that a protein fold with sufficient stability to perform its biological functions. We present...Full Text Available

2009-04-01

227

Identification of the Response Parameters of a Geothermal Field During a Non-Isothermal Short Time Water Injection Test.

The use of Bacillus thuringiensis (Bt) endotoxins to control insect vectors of human diseases and agricultural pests is threatened by the possible evolution of resistance in major pest...Full Text Available

2004-03-02

228

How do planetary nebulae evolve

Various methods to analyse the effect of a non-isotherme water injection on the pressure evolution during a test on a double geothermal well are investigated. Then, several types of injection test are simulated with experimental data to examine the condit...

1983-01-01

229

How Protein Stability and New Functions Trade Off

This article throws light on an only recently understood but important development of star evolution - that of the occurrence of planetary nebulae. The process is controlled by thermonuclear physics and gravitation and now and again greatly influenced by mass loss.

1982-01-01

230

Honing the Dagger: The formation of a Standing Joint Special Operations Task Force Headquarters.

Numerous studies have noted that the evolution of new enzymatic specificities is accompanied by loss of the protein's thermodynamic stability (ΔΔG), thus suggesting...Full Text Available

2008-02-01

231

Hominin life history: reconstruction and evolution

This monograph explores an alternative way of providing a JSOTF headquarters to the Joint Force Commander. Beginning with a history of joint SOF doctrine, the monograph outlines the evolution of special operations command and control and the subsequent ne...

2005-01-01

232

Genomic patterns of pathogen evolution revealed by comparison of Burkholderia pseudomallei, the causative agent of melioidosis, to avirulent Burkholderia thailandensis

In this review we attempt to reconstruct the evolutionary history of hominin life history from extant and fossil evidence. We utilize demographic life history theory and distinguish life history variables,...Full Text Available

2008-04-01

233

Genomic Diversity and Evolution of Mycobacterium ulcerans Revealed by Next-Generation Sequencing

BackgroundThe Gram-negative bacterium Burkholderia pseudomallei (Bp) is the causative agent of the human disease melioidosis. To understand the evolutionary mechanisms...Full Text Available

234

Genomic Content of Bordetella pertussis Clinical Isolates Circulating in Areas of Intensive Children Vaccination

Mycobacterium ulcerans is the causative agent of Buruli ulcer, the third most common mycobacterial disease after tuberculosis and leprosy. It is an emerging infectious disease that...Full Text Available

2009-09-01

235

Examples of degenerated matter in astrophysics: white dwarf and neutron stars

BackgroundThe objective of the study was to analyse the evolution of Bordetella pertussis population and the influence of herd immunity in different areas of the...Full Text Available

236

Evolutionary history of a specialized P450 propane monooxygenase

Main features of star evolution are recalled. Then the general structure of white dwarf stars is examined. From the equation of state of an electron gas completely degenerated are deduced: mechanical equilibrium, Viriel theorem, mass-radius relationship and Chandrasekhar limit. These results are applied to neutron stars.

1982-06-01

237

Evolutionary Trajectories of Beta-Lactamase CTX-M-1 Cluster Enzymes: Predicting Antibiotic Resistance

SummaryThe evolutionary pressures that shaped the specificity and catalytic efficiency of enzymes can only be speculated. While directed evolution experiments show that new functions...Full Text Available

2008-11-28

238

Evolution of the redox function in mammalian Apurinic/apyrimidinic endonuclease

Extended-spectrum beta-lactamases (ESBL) constitute a key antibiotic-resistance mechanism affecting Gram-negative bacteria, and also an excellent model for studying evolution in real time. A shift in...Full Text Available

2010-01-01

239

Evolution of feeding specialization in Tanganyikan scale-eating cichlids: a molecular phylogenetic approach

Human apurinic/apyrimidinic endonuclease (hApe1) encodes two important functional activities: an essential base excision repair (BER) activity and a redox activity that regulates expression...Full Text Available

2008-08-25

240

Evolution of age at menarche and at onset of regular cycling in a large cohort of French women

BackgroundCichlid fishes in Lake Tanganyika exhibit remarkable diversity in their feeding habits. Among them, seven species in the genus Perissodus are known for...Full Text Available

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241

Evolution of Thermal Response Properties in a Cold-Activated TRP Channel

BackgroundEarly exposure to ovarian hormones is considered to increase breast cancer incidence. The age at which the ovaries become functional is thus important.Full Text Available

2002-01-01

242

Evolution of DMY, a newly emergent male sex-determination gene of medaka fish.

Animals sense changes in ambient temperature irrespective of whether core body temperature is internally maintained (homeotherms) or subject to environmental variation (poikilotherms). Here we show...Full Text Available

243

Evolution and Optimality of Similar Neural Mechanisms for Perception and Action during Search

The Japanese medaka fish Oryzias latipes has an XX/XY sex-determination system. The Y-linked sex-determination gene DMY is a duplicate of the autosomal gene DMRT1, which encodes a DM-domain-containing...Full Text Available

2004-04-01

244

Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull

A prevailing theory proposes that the brain's two visual pathways, the ventral and dorsal, lead to differing visual processing and world representations for conscious perception than those for action....Full Text Available

2010-09-01

245

Economic regulation and hospital behavior: the effects on medical staff organization and hospital-physician relationships.

The fossil record is a unique source of evidence for important evolutionary phenomena such as transitions between major clades. Frustratingly, relevant fossils are still comparatively rare, most transitions...Full Text Available

2010-02-07

246

EVOLUTION OF MASSIVE STARS WITH PULSATION-DRIVEN SUPERWINDS DURING THE RED SUPERGIANT PHASE

New forms of payment, growing competition, the continued evolution of multiunit hospital systems, and associated forces are redefining the fundamental relationship between hospitals and physicians....Full Text Available

1985-12-01

247

Dynamical evolution driven by bars and interactions Input from numerical simulations

Pulsations driven by partial ionization of hydrogen in the envelope are often considered important for driving winds from red supergiants (RSGs). In particular, it has been suggested by some authors that the pulsation growth rate in an RSG can be high enough to trigger an unusually strong wind (or a superwind), when the luminosity-to-mass ratio becomes sufficiently large. Using both hydrostatic and hydrodynamic stellar evolution models with initial masses ranging from 15 to 40 M_s_u_n, we investigate (1) how the pulsation growth rate depends on the global parameters of supergiant stars and (2) what would be the consequences of a pulsation-driven superwind, if it occurred, for the late stages of massive star evolution. We suggest that such a superwind history would be marked by a runaway increase, followed by a sudden decrease, of the wind's mass-loss rate. The impact on the late evolution of massive stars would be ...

2010-07-01

248

Dynamic nucleation of new grains in magnesium alloy during hot deformation

We discuss the evolution of a disc galaxy due to the formation of a bar and, subsequently, a peanut. After the formation stage there is still considerable evolution, albeit slower. In purely stellar cases the pattern speed of the bar decreases with time, while its amplitude grows. However, if a considerable gaseous component is present in the disc, the pattern speed may increase with time, while the bar strength may decrease. In some cases the gas can be brought sufficiently close to the center to create a strong central concentration, which, in turn, may modify the properties of the bar. More violent evolution can take place during interactions, so that some disc substructures can be either formed or destroyed in a time scale which is small compared to a Hubble time. These include spirals, bars, bridges, tails, rings, thick discs and bulges. In some cases interactions may lead to mergings. We briefly review comparisons of ...

2002-01-01

249

Duplication and Diversification of the Hypoxia-Inducible IGFBP-1 Gene in Zebrafish

Microstructure evolution under hot deformation was investigated in compression of a magnesium alloy AZ31 at 673 K (0.73T{sub m}). Two kinds of samples were machined along the parallel and transverse direction of the extruded rods. New fine grains are evolved at corrugated grain boundaries at low strains and developed rapidly in grain interiors in the medium range of strain, finally leading to a roughly full evolution of equiaxial fine grains. Kink bands are evolved at corrugated grain boundaries and in grain interiors at low strains. The boundary misorientation of kink band increases rapidly with increasing strain. These characteristics of new grain evolution process are not changed by the orientation of the samples, while the flow behaviors clearly depend on it. It is concluded that new grain evolution can be controlled by a deformation-induced continuous reaction resulting in grain fragmentation by ...

2003-07-01

250

Doublet III vacuum vessel neutral beam armor

BackgroundGene duplication is the primary force of new gene evolution. Deciphering whether a pair of duplicated genes has evolved divergent functions is often challenging. The zebrafish...Full Text Available

251

Dissipative particle swarm optimization

The evolution of the Doublet III neutral beam armor is followed from the initial design of a radiation cooled metallic tile to the present actively cooled graphite design. Results of the thermal and stress analyses that dictated the present design are reviewed.

1979-11-01

252

Dissecting the Genetic Components of Adaptation of Escherichia coli to the Mouse Gut

A dissipative particle swarm optimization is developed according to the self-organization of dissipative structure. The negative entropy is introduced to construct an opening dissipative system that is far-from-equilibrium so as to driving the irreversible evolution process with better fitness. The testing of two multimodal functions indicates it improves the performance effectively

2005-01-01

253

Developmental plasticity and the evolution of animal complex life cycles

While pleiotropic adaptive mutations are thought to be central for evolution, little is known on the downstream molecular effects allowing adaptation to complex ecologically relevant environments. Here...Full Text Available

2008-01-01

254

Comparative genomics of the bacterial genus Listeria: Genome evolution is characterized by limited gene acquisition and limited gene loss

Metazoan life cycles can be complex in different ways. A number of diverse phenotypes and reproductive events can sequentially occur along the cycle, and at certain stages a variety of developmental...Full Text Available

2010-02-27

255

Choosing a future for epidemiology: I. Eras and paradigms.

BackgroundThe bacterial genus Listeria contains pathogenic and non-pathogenic species, including the pathogens L. monocytogenes and L. ivanovii,...Full Text Available

256

Characterization of the Key Step for Light-driven Hydrogen Evolution in Green Algae*

To inform choices about the future of epidemiology, the present condition of epidemiology is examined, in terms of its evolution through three eras, each demarcated by its own paradigm: (1) the era...Full Text Available

1996-05-01

257

Characterization of Photosystem II Activity and Heterogeneity during the Cell Cycle of the Green Alga Scenedesmus quadricauda1

Under anaerobic conditions, several species of green algae perform a light-dependent hydrogen production catalyzed by a special group of [FeFe] hydrogenases termed HydA. Although highly interesting...Full Text Available

2009-12-25

258

Can Deterministic Mechanical Size Effects Contribute to Fracture and Microdamage Accumulation in Trabecular Bone?

The photosynthetic activity of the green alga Scenedesmus quadricauda was investigated during synchronous growth in light/dark cycles. The rate of O₂ evolution increased...Full Text Available

1999-06-01

259

Boule and the Evolutionary Origin of Metazoan Gametogenesis: A Grandpa's Tale

Failure of bone under monotonic and cyclic loading is related to the bone mineral density, the quality of the bone matrix and the evolution of microcracks. The theory of linear elastic fracture...Full Text Available

2010-07-21

260

Biochemical Conservation and Evolution of Germacrene A Oxidase in Asteraceae*

The evolution of sex remains a hotly debated topic in evolutionary biology. In particular, studying the origins of the molecular mechanisms underlying sexual reproduction and gametogenesis (its fundamental...Full Text Available

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261

Sesquiterpene lactones are characteristic natural products in Asteraceae, which constitutes ∼8% of all plant species. Despite their physiological and pharmaceutical importance, the biochemistry...Full Text Available

2010-05-28

262

Big bang nucleosynthesis

Astronomical and astrophysical research activities of the Institute of Astronomy

The concordance of standard big bang nucleosynthesis theory and the related observations of the light element isotopes (including some new higher {sup 4}He abundances) will be reviewed. Implications of BBN on chemical evolution, dark matter and constraints on particle properties will be discussed.

1999-01-01

263

Are Petals Sterile Stamens or Bracts? The Origin and Evolution of Petals in the Core Eudicots

Observational work on quasars, galaxies, and stars is summarized. Theoretical studies covering stars and stellar evolution, galaxies, clusters and cosmology, high energy astrophysics the solar system and the Sun are described. (ESA)

1980-01-01

264

Amorphous to crystalline phase transformation in Metglas reg-sign studied by Moessbauer spectroscopy

BackgroundThe aim of this paper is to discuss the controversial origins of petals from tepals or stamens and the links between the morphological expression of petals and floral organ...Full Text Available

2007-09-01

265

AeroSpace Information for a Changing World - NASA Technical ...

The authors present differential scanning calorimetry (DSC) and in situ Moessbauer spectroscopy results for Metglas ribbons, to which different heat treatments were made. The Curie temperature of the amorphous phase is determined and the evolution of the magnetic field of this phase is studied as a function of temperature

1997-12-01

266

Acetaldehyde Oxime, A Product Formed during the In Vivo Nitrate Reductase Assay of Soybean Leaves 1

Probing Neutron Star Evolution with Gamma Rays Online Source: Click to View PDF File [PDF Size: 217 KB] Author: Wijers, Ralph A. M. J. ...

267

A new perspective on phylogeny and evolution of tetraodontiform fishes (Pisces: Acanthopterygii) based on whole mitochondrial genome sequences: Basal ecological diversification?

Evolution of nitrogen oxides (NO_(x), primarily as nitric oxide) from soybean (Glycine max [L.] Merr.) leaves during purged in vivo nitrate reductase assays...Full Text Available

1984-09-01

268

A Preference for a Sexual Signal Keeps Females Safe

BackgroundThe order Tetraodontiformes consists of approximately 429 species of fishes in nine families. Members of the order exhibit striking morphological diversity and radiated...Full Text Available

269

The evolution of rigid-plastic dynamic response by mathematical programming

Predation is generally thought to constrain sexual selection by female choice and limit the evolution of conspicuous sexual signals. Under high predation risk, females usually become less choosy, because...Full Text Available

270

Spatial structure of compound dither in L/H transition

This paper presents a systematic approach to the automatic determination of the evolution of the rigid-plastic structural response caused by a proportional or single parameter pressure loading which varies with time in a monotonic non decreasing fashion. The frame structure is envisaged as a network, and the fundamental vectorial conditions characterising its behaviour at any instant of time are combined in a consistent manner. By considering the level of the pressure loading to be a single load parameter ranging monotonically from zero to infinity, the structural governing system may be regarded as a parametric linear complementary problem. (author). 13 refs., 2 figs.

1995-12-31

271

Simulation of flame-vortex interaction using detailed and reduced

To study the plasma evolution and spatial structure at the L/H transition, the double hysteresis is examined by use of the 1-dimensional transport model equations. Three mechanisms for the bipolar losses, i.e., the loss cone loss, collisional bulk viscosity loss of ions and the anomalous loss are simultaneously retained. Five-fold multiple bifurcations are found to exist at the plasma edge, similar to the previous 0-dimensional study. Double hysteresis causes a self-generated oscillation, which is attributed to the compound dither, a kind of ELMs. Spatio-temporal evolution of the compound dither is analyzed. (author)

2000-03-01

272

Silicidation in Pd/Si thin film junction-Defect evolution and silicon surface segregation

The interaction between a pair of counter-rotating vortices and a lean premixed CH{sub 4}/O{sub 2}/N{sub 2} flame ({Phi} = + 0.55) has been studied by direct numerical simulations using detailed and reduced chemical reaction schemes. Results from the complex chemistry simulation are discussed with respect to earlier experiments and differences in the simulations using detailed and reduces chemistry are investigated. Transient evolutions of the flame surface and the total heat release rate are compared and modifications in the evolution of the local flame structure are displayed. (authors) 22 refs.

1996-12-31

273

Oxygen evolution studies on perovskite films in alkaline media

Depth resolved positron annihilation studies on Pd/Si thin film system have been carried out to investigate silicide phase formation and vacancy defect production induced by thermal annealing. The evolution of defect sensitive S-parameter clearly indicates the presence of divacancy defects across the interface, due to enhanced Si diffusion beyond 870 K consequent to silicide formation. Corroborative glancing incidence X-ray diffraction (GIXRD), Auger electron spectroscopy (AES) and Rutherford backscattering spectrometry (RBS) have elucidated the aspects related to silicide phase formation and Si surface segregation.

2007-09-25

274

Overview of future evolution of the specific consumption of electric energy in the primary aluminium Brazilian industry; Perspectivas de evolucao futura do consumo especifico de energia eletrica na industria brasileira de aluminio primario

Thin films of La{sub 0.6}Ca{sub 0.4}CoO{sub 3} perovskite were deposited on nickel plates by thermal decomposition of the metal nitrates. The electrochemical activity of the films for oxygen evolution in KOH solutions (0.1-1 M) was investigated. The reaction order with respect to OH{sup -} ion was found to be around 0.7. The results correlate fairly well with a mechanism in which breaking of the intermediate metal-peroxide bond at the Co ion is the rate-determining step. (author) 4 figs., 4 refs.

1999-08-01

275

Mira variables - Pulsation, mass loss and evolution

This article introduces the actual artistic state in energy performance terns of the primary aluminium production in Brazil and in the world. Besides, it is evaluated the future evolution perspectives of the electrical specific consumption in the industrial sector, due to the technological innovation and determined capacity eventual expansions in the productive process. 6 refs., 2 figs, 4 tabs

1996-12-31

276

Light elements in massive single and binary stars

Recent developments in the analysis of Mira atmosphere, the determination of the pulsation mode, the problem of mass loss, and the evolution of the Mira variables are covered. Model atmospheres for Mira variables, including the opacities of the molecules expected in very late M-type atmospheres are discussed. The pulsation constant for Omicron Ceti is evaluated using T(eff) = 2900 + or - 200 K, and it is concluded that Miras are fundamental mode pulsators. The importance of molecular opacity to the driving of mass loss is evaluated, and it is pointed out that the radiation pressure on molecules is not a major factor in driving mass loss from Mira. Mass loss is considered as a factor in the calculations of the periods for Mira variables. 30 refs.

1990-05-28

277

Experimental determination of the evolution of organic matter thermal maturity indicators. Application to the Toarcian kerogens from the Paris basin

We highlight the role of the light elements (Li, Be, B) in the evolution of massive single and binary stars, which is largely restricted to a diagnostic value, and foremost so for the element boron. However, we show that the boron surface abundance in massive early type stars contains key information about their foregoing evolution which is not obtainable otherwise. In particular, it allows to constrain internal mixing processes and potential previous mass transfer event for binary stars (even if the companion has disappeared). It may also help solving the mystery of the slowly rotating nitrogen-rich massive main sequence stars.

2010-01-01

278

Evolution of the white dwarf mass and spin in cataclysmic variables

The experimental maturation of an immature kerogen from the Toarcian of the Paris basin has been carried out in a confined system under pressure. The evolution of various thermal maturity parameters was plotted against the corrected organic carbon percentage chosen as a common maturity indicator and compared with data extracted from a natural series. Results show the occurrence of three distinct stages respectively characterized by the removal of oxygenated compounds, the genesis of liquid hydrocarbons and the production of gaseous hydrocarbons.

1989-03-01

279

Evolution of reactivity control mechanisms for nuclear research and power reactors in India

We consider the spin-up of the white dwarf in non-magnetic cataclysmic variables (CVs) during secular evolution. If this is unresisted, CVs are quenched as boundary-layer emitters once the binary period has decreased by #approx# 1 hr. Angular momentum loss in nova explosions may, however, prevent the star reaching breakup. If the explosions remove (1 + #epsilon#) x the mass accreted between outbursts, values 0.5 < #approx# #epsilon# < #approx# 1 allow CVs to be modest boundary-layer emitters for most of their lifetimes. Spectral effects will limit their detection as soft X-ray sources. (author).

280

Evolution of binary stars in the LMC with helium enrichment

Division of Remote Handling and Robotics (DRHR) at Bhabha Atomic Research Centre (BARC) has been working on design and development of Reactivity Control Mechanisms for Nuclear Research Reactors (Dhruva, KAMINI and recently Critical Facility of Advanced Heavy Water Reactor (AHWR)) as well as Power Reactors in India (Pressurized Heavy Water Reactors of 220 MWe at Narora and recently India's first 540 MWe PHWR Unit -1 and 2 at Tarapur). This paper gives a brief account of evolution of reactivity control mechanisms for nuclear research and power reactors in India. (author)

2009-10-01

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281

Effects of the variation of fundamental constants on Pop III stellar evolution

Recent surveys of supergiants stars in the LMC indicate that the post-main-sequence region of the colour-magnitude diagram is well populated, although numerical evolution of massive stars with normal surface hydrogen indicates to the contrary. Supergiant stars having surface enrichment of helium acquired for example from a previous phase of accretion from a binary companion, however, evolve in a way so that the evolved models and observed data are consistent. We compare the available data with computed evolutionary tracks of massive stars of metallicity relevant to the LMC with and without helium-enriched envelopes and conclude that a large fraction of supergiant stars may occur in binaries. (author).

282

Confrontation between stellar pulsation and evolution; Proceedings of the Conference (ASP Series, Vol. 11), Bologna, Italy, May 28-31, 1990

The effect of variations of the fundamental constants on the thermonuclear rate of the triple alpha reaction, "4He(#alpha##alpha#, #gamma#)"1"2C, that bridges the gap between "4He and "1"2C is investigated. We have followed the evolution of 15 and 60 M#centre dot# zero metallicity stellar models, up to the end of core helium burning. They are assumed to be representative of the first (Population III) stars. The calculated oxygen carbon abundances resulting from helium burning can then be used to constrain the variation of the fundamental constants.

2010-08-12

283

Common envelope evolution

Attention is given to the folowing topics: population I and II variable stars; LP variables, the sun, and mass determination; and predegenerate and degenerate variables. Particular papers are presented on alternative evolutionary approaches to the absolute magnitude of the RR Lyrae variables; the evolution of the Cepheid stars; nonradial pulsations in rapidly rotating Delta Scuti stars; dynamical models of dust shells around Mira variables; and pulsations of central stars of planetary nebulae.

1990-05-28

284

British Library Electronic Table of Contents (United Kingdom)

The common envelope phase of binary star evolution plays a central role in many evolutionary pathways leading to the formation of compact objects in short period systems. Using three dimensional hydrodynamical computations, we review the major features of this evolutionary phase, focusing on the conditions that lead to the successful ejection of the envelope and, hence, survival of the system as a post common envelope binary. Future hydrodynamical calculations at high spatial resolution are required to delineate the regime in parameter space for which systems survive as compact binary systems from those for which the two components of the system merge into a single rapidly rotating star. Recent algorithmic developments will facilitate the attainment of this goal.

2010-01-01

285

A Nash-Moser theorem for singular evolution equations. Application to the Serre and Green-Naghdi equations

Study of the lattice parameter evolution of PWR irradiated MOX fuel by X-Ray diffraction; Etude de l'evolution du parametre cristallin des combustibles MOX irradies en rep par la methode de diffraction des rayons X

We study the well-posedness of the initial value problem for a wide class of singular evolution equations. We prove a general well-posedness theorem under three assumptions easy to check: the first controls the singular part of the equation, the second the behavior of the nonlinearities, and the third one assumes that an energy estimate can be found for the linearized system. We allow losses of derivatives in this energy estimate and therefore construct a solution by a Nash-Moser iterative scheme. As an application to this general theorem, we prove the well-posedness of the Serre and Green-Naghdi equation and discuss the problem of their validity as asymptotic models for the water-waves equations.

2007-01-01

286

Helical CT defecography; La defecografia con Tomografia Computerizzata spirale

Fuel irradiation leads to a swelling resulting from the formation of gaseous (Kr, Xe) or solid fission products which are found either in solution or as solid inclusions in the matrix. This phenomena has to be evaluated to be taken into account in fuel cladding Interaction. Fuel swelling was studied as a function of burn up by measuring the corresponding cell constant evolution by X-Ray diffraction. This study was realized on Mixed Oxide Fuels (MOX) irradiated in a Pressurized Water Reactor (PWR) at different burn-up for 3 initial Pu contents. Lattice parameter evolutions were followed as a function of burn-up for the irradiated fuel with and without an annealing thermal treatment. These experimental evolutions are compared to the theoretical evolutions calculated from the hard sphere model, using the fission product concentrations determined by the APPOLO computer code. Contribution of varying ...

1995-07-01

287

CT and MRI characteristica of tumours of the temporal bone and the cerebello-pontine angle; CT und MRT tumoroeser Veraenderungen des Schlaefenbeins

The purpose of this work is to investigate the possible role of Helical CT defecography in pelvic floor disorders by comparing the results of the investigations with those of conventional defecography. The series analyzed consisted of 90 patients, namely 62 women and 28 men, ranging in age 24-82 years. They were all submitted to conventional defecography, and 18 questionable cases were also studied with Helical CT defecography. The conventional examination was performed during the 4 standard phases of resting, squeezing, Valsalva and straining; it is used a remote-control unit. The parameters for Helical CT defecography were: 5 mm beam collimation, pitch 2, 120 KV, 250 m As and 18-20 degrees gantry inclination to acquire coronal images of the pelvic floor. The rectal ampulla was distended with a bolus of 300 mL nonionic iodinated contrast agent (dilution: 3g/cc). The patient wore a napkin and was seated on the table, except for those who could not hold the position ...

1999-11-01

288

New procedures. Comprehensive staging of lung cancer by MRI; Neue Verfahren. Umfassendes Staging des Lungenkarzinoms mit der MRT

Tumours lesions of the temporal bone and of the cerebello-pontine angle are rare.This tumours can be separated into benign and malignant lesions. In this paper the CT and MRI characteristica of tumours of the temporal bone and the cerebello-pontane angle will be demonstrated. High resolution CT (HRCT) as usually performed in the axial plane are using a high resolution bone window level setting, coronal planes are the reconstructed from the axial data set or will be obtained directly. With the MRI FLAIR sequence in the axial plane the whole brain will be scanned either to depict or exclude a tumour invasion into the brain. After this,T2-weighted fast spin echo sequences or fatsuppressed inversion recovery sequences in high resolution technique in the axial plane will be obtained from the temporal bone and axial T1-weighted spinecho sequences before and after the intravenous application of contrast material will be obtained of this region. Finally T1-weighted ...

2003-03-01

289

MRT of the abdomen in combination with enteroclysis in Crohn disease with oral and intravenous Gd-DTPA; MRT des Abdomens in Kombination mit der Enteroklyse bei Morbus Crohn unter Verwendung von oralem und intravenoesem Gd-DTPA

Lung cancer staging according to the TNM system is based on morphological assessment of the primary cancer, lymph nodes and metastases. All aspects of this important oncological classification are measurable with MRI. Pulmonary nodules can be detected at the clinically relevant size of 4-5 mm in diameter. The extent of mediastinal, hilar and supraclavicular lymph node affection can be assessed at the same time. The predominant metastatic spread to the adrenal glands and spine can be detected in coronal orientation during dedicated MRI of the lungs. Search focused whole body MRI completes the staging. Various additional MR imaging techniques provide further functional and clinically relevant information during a single examination. In the oncological context the most important techniques are imaging of perfusion and tumor motion. Functional MRI of the lungs complements the pure staging and improves surgical approaches and radiotherapy planning. (orig.) [German] Das ...

2010-08-15

290

Comparison of high resolution whole-body MRI using parallel imaging and PET-CT. First experiences with a 32-channel MRI system

60 patients between 17 and 72 years of age were investigated. First, an enteroclysis was performed in typical manner. The applicated methylcellulosis was blended with positive oral MR contrast media (Magnevist oral, Schering). After enteroclysis, MRI of the abdomen was performed using T1- and T2-weighted breathhold sequences (Flash 2D pre- and postcontrast and TSE) in axial and coronal planes. The length of the affected bowel and the stenosis seen with enteroclysis correlated well with the visible thickening of the small bowel wall and the stenosis seen in MRI. Using MRI, additional findings could be obtained in 28 patients, such as fistulas, abscesses or a hydronephrosis, or a better assessment of the stenosis was possible with MRI, because of the avoidance of overshadowing of the affected bowel loop with MRI. A brilliant MR-tomographic imaging of the small bowel is possible under the condition, that the small bowel contrast is optimal. The main prerequisite is a ...

1998-01-01

291

3D MRI of the colon: methods and first results of 5 patients; 3D-MRT des Kolons: Methodik und erste Ergebnisse

To compare the accuracy in the detection and staging of various malignant tumors with high resolution whole-body MRI using parallel imaging with whole-body dual-modality PET-CT. Preliminary results of an interim analysis from a prospective, blinded study are presented, in which 20 patients (mean age 59 years, range 27-77 years) with different oncological diseases underwent whole-body dual modality FDG-PET-CT screening for tumor search or staging in case of confirmed or suspected metastatic disease. All patients also underwent whole-body MRI imaging with the use of parallel imaging (iPAT). High-resolution coronal T1w- and STIR-sequences of 5 body levels with 512 x 512 matrix, axial fast T2w imaging of lung and abdomen (HASTE), contrast-enhanced dynamic and static T1w-sequences of liver, brain, abdomen, and pelvis were performed. Using a 32-channel whole-body MRI scanner (Magnetom Avanto, Siemens Medical Solutions) with a total field of view of 205 cm and free table ...

292

Impurity and clustering effects on defect evolution in ion-implanted Si

Purpose: `Exoscopic` and endoscopic identification of colorectal pathologies via MRI. Methods: 5 patients (36-88 years), two normal and three with different colorectal pathologies (diverticular disease, polyps and carcinoma of the colon), were examined by MRI after colonoscopy. Subsequent to filling of the colon with a gadolinium-water mixture under MRI-monitoring, 3D-data sets of the colon were acquired in prone and supine positions over a 28 sec breathold interval. Subsequently multiplanar T{sub 1}-weighted 2D-sequences were acquired before and following i.v. administration of Gd-DTPA (0.1 mmol/kg BW). All imaging was performed in the coronal orientation. The 3D-data were interactively analysed based on various displays: Maximum intensity projection (MIP), surface shadowed display (SSD), multiplanar reconstruction (MPR), virtual colonoscopy (VC). Results: All of the colorectal pathologies could be interactively diagnosed by MPR. On MIP images some pathologies ...

1997-09-01

293

Frontiers of Nuclear Astrophysics

A detailed investigation of the damage formation and evolution in ion-implanted crystalline Si is presented. Deep-level transient spectroscopy has been used to monitor room temperature migration of point defect complexes and evolution from simple point-like defect complexes to defect clusters and even extended defects. Si samples were implanted with Si or He ions with energies of 145 keV-3MeV, to fluences in the range 5x10[sup 8]-5x10[sup 13]cm[sup -2]. The effects of thermal annealing, in the range 100-680 C and 10 min-15h, were also explored. A systematic comparison of defect complexes formation and evolution in ion-implanted or electron-irradiated Si samples with a different impurity content were used to assess the role of impurities (C and O), extra implanted ion and defect clustering on the nature and thermal stability of residual damage. In particular, an interstitial excess directly resulting from the extra implanted ...

1998-10-01

294

[Fe]-hydrogenases in green algae: photo-fermentation and hydrogen evolution under sulfur deprivation

The main goals of nuclear astrophysics have been to probe the interiors of stars, stellar explosions, the early moments of cosmic expansion, and the formation and evolution of galaxies and cosmic structure by measurement and application of the relevant nuclear physics. The approach to these goals have generally been from three directions: 1) Careful measurements of the relevant nuclear reactions; 2) Detailed computer models of the relevant astrophysical environments; and 3) Observations of the relevant terrestrial and extra-terrestrial atomic and isotopic abundances. These approaches provide not only insight into the formation and evolution of the elements, but are also pillars upon which a variety of cosmological models as well as models for physics beyond the standard model of particle physics can stand or fall. At present there is a very exciting frontier on all three of these approaches. The development and applications of ...

2008-06-01

295

The influence of yttrium (Y) on the corrosion of Mg-Y binary alloys

Recent studies indicate that [Fe]-hydrogenases and H{sub 2} metabolism are widely distributed among green algae. The enzymes are simple structured and catalyze H{sub 2} evolution with similar rates than the more complex [Fe]-hydrogenases from bacteria. Different green algal species developed diverse strategies to survive under sulfur deprivation. Chlamydomonas reinhardtii evolves large quantities of hydrogen gas in the absence of sulfur. In a sealed culture of C. reinhardtii, the photosynthetic O{sub 2} evolution rate drops below the rate of respiratory O{sub 2} consumption due to a reversible inhibition of photosystem II, thus leading to an intracellular anaerobiosis. The algal cells survive under these anaerobic conditions by switching their metabolism to a kind of photo-fermentation. Although possessing a functional [Fe]-hydrogenase gene, the cells of Scenedesmus obliquus produce no significant amounts of H{sub 2} under S-depleted ...

2002-12-01

296

The evolution of AGB stars with convective overshoot

Research highlights: #-># The Y-intermetallic can accelerate corrosion and Y can increase the protectiveness of the surface layer. #-># In 0.1 M NaCl, the corrosion rate of Mg-Y alloys increased with increasing Y due to the Y intermetallic. #-># In 0.1 M NaCl, there was filiform corrosion. #-># In 0.1 M Na_2SO_4, the corrosion rate of Mg-Y alloys decreased with increasing Y in the range 3-7%Y. #-># Hydrogen evolution was observed from particular parts of the alloy surface. - Abstract: Corrosion of Mg-Y alloys was studied using electrochemical evaluations, immersion tests and direct observations. There were two important effects. In 0.1 M NaCl, the corrosion rate increased with increasing Y content due to increasing amounts of the Y-containing intermetallic. In 0.1 M Na_2SO_4, the corrosion rate decreased with increasing Y content above 3%, attributed to a more protective surface film, despite the intermetallic. The corrosion rate evaluated by ...

2010-11-01

297

The Secondary Stars of Cataclysmic Variables

The influence of extended convective mixing (overshoot) on asymptotic giant branch stellar evolution is investigated in detail. The extended mixing is treated time-dependently, and the efficiency declines exponentially with the geometric distance from the convective boundary. It has been considered at all convective boundaries, including the He-flash convection zone in the intershell region which forms during the thermal pulses. Both the structural and the chemical evolution are affected by the inclusion of overshoot. The main results include a very efficient third dredge-up which leads to the formation of carbon stars of low mass and luminosity. A C13 pocket which may serve as a neutron source for the s-process can form after the third dredge-up has reached into the C12 rich intershell. Overshoot applied to the pulse-driven convective zone during the He-flash leads to a deeper penetration of the bottom of this convective zone into the C/O core ...

2000-01-01

298

Structure evolution of the LiMnO{sub 2} lamellar oxide during electrochemical cycling; Evolution structurale de l`oxyde lamellaire LiMnO{sub 2} lors du cyclage electrochimique

I review what we know about the donor stars in cataclysmic variables (CVs), focusing particularly on the close link between these binary components and the overall secular evolution of CVs. I begin with a brief overview of the "standard model" of CV evolution and explain why the key observables this model is designed to explain - the period gap and the period minimum -- are intimately connected to the properties of the secondary stars in these systems. CV donors are expected to be slightly inflated relative to isolated, equal-mass main-sequence (MS) stars, and this "donor bloating" has now been confirmed observationally. The empirical donor mass-radius relationship also shows a discontinuity at M_2 = 0.2 M_sun which neatly separates long- and short-period CVs. This is strong confirmation of the basic disrupted magnetic braking scenario for CV evolution. The empirical M_2-R_2 relation can be combined with stellar models to ...

2011-01-01

299

Monitoring processes and measuring the effectiveness of the management system

The LiMnO{sub 2} lamellar oxide, obtained by exchange reaction from its sodium homologue {alpha}-NaMnO{sub 2}, has been used as a positive electrode for lithium batteries. After the first electrochemical cycle, the shape of the potential-composition curve changes and indicates a change in the structure. This modification changes imperceptibly at each cycle and after about 40 cycles, a stationary state is reached. Powder spectra refinement using the Rietvelt method shows a migration of manganese ions from the thin sheets towards the inter-sheet space. After a single cycle, 8% of the manganese ions are already present in the lithium site and this rate reaches 13% after 3 cycles. During long cycling, a redistribution of ions and vacancies inside the cfc oxygenated pile leads to a structure very similar to the LiMn{sub 2}O{sub 4} spinel. This structure evolution is to be compared with the one obtained from the orthorhombic variety of LiMnO{sub 2} but the modification ...

1996-12-31

300

Hydrogen evolution reaction on single crystal WO3/C nanoparticles supported on carbon in acid and alkaline solution

This document presents the way which the 8th principle of the quality management system 'Process approach' is applied, the principle that is identified and used by international standard ISO 9000. In order to understand the evolution of the management system requirements, as used today in different activities namely, industry, services, and nuclear activities, the authors present an evolution of the quality concept and its traceability to different standards, applicable in time. There are described the requirements of ISO 9001 standard, that represents the most widely spread model for modern organization management and the IAEA concerns related to integration of the above standard requirements into the most recent safety IAEA standard 'The Management System for facilities and activities'. The IAEA Safety Standard GS-R-3 describes a management model considering both the evolution of the quality requirements into the modern ...

2009-10-12

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301

British Library Electronic Table of Contents (United Kingdom)

Single crystal tungsten oxide (WO3) nanoparticles were prepared via a microwave-assisted method. Electrochemical activity for hydrogen evolution reaction (HER) on WO3 supported on carbon black (WO3/C) electrocatalyst was first studied in acid solution (0.5 M H2SO4) and alkaline solution (1.0 M KOH) at room temperature. The overall experimental results revealed that the electrocatalytic activity for HER on WO3/C is one order magnitude higher than those obtained with carbon black in 0.5 M H2SO4 and is six times than in the case of carbon black in 1.0 M KOH. These results demonstrated that WO3 could enhance the electrocatalytic activity for hydrogen evolution reaction in acid solution (0.5 M H2SO4) and alkaline solution (1.0 M KOH). On the other hand, the kinetic reaction mechanisms were disc...

2011-01-01

302

Heterogeneous radiolysis of HCN adsorbed on a solid surface

GAS EVOLUTION FROM INSULATING MATERIALS FOR SUPERCONDUCTING COIL OF ITER BY GAMMA RAY IRRADIATION AT LIQUID NITROGEN TEMPERATURE

Hydrogen cyanide is a key molecule for chemical evolution studies because, when it is exposed to different sources of energy, it forms various compounds of biological importance. To understand the role of minerals in chemical evolution, a series of experiments was performed. First, the adsorption capacity of HCN on different surface minerals was studied; the results show that HCN is readily adsorbed onto the solids proposed (zeolite, serpentine, dolomite, and sodium montmorillonite), in particular zeolite and montmorillonite. Second, the radiolysis of HCN adsorbed on olivine (as an example of a mineral surface) was also followed; it was found that the rate of HCN decomposition by gamma irradiation is enhanced in the presence of the solid. The third series of studies show that organic material was produced in high abundance from HCN at high radiation doses. The radiolytic products included gases (CO_2, NH_4, and CO) and oligomeric materials that ...

2010-07-01

303

Evolution and perspectives in waste incineration emissions and flue gas cleaning systems in the last 20 years

A laminated material composed of glass cloth/polyimide film/epoxy resin will be used as an insulating material for superconducting coil of International Thermonuclear Experimental Reactor (ITER). In order to keep safe and stable operation of the superconducting coil system, it is indispensable to evaluate radiation resistance of the material, because the material is exposed to severe environments such as high radiation field and low temperature of 4 K. Especially, it is important to estimate the amount of gases evolved from the insulating material by irradiation, because the gases affect on the purifying system of liquid helium in the superconducting coil system. In this work, the gas evolution from the laminated material by gamma ray irradiation at liquid nitrogen temperature (77 K) was investigated, and the difference of gas evolution behavior due to difference of composition in the epoxy resin was discussed. It was found that the main gases ...

2008-03-03

304

Effect of the Ge preamorphization dose on boron diffusion and defect evolution in silicon

The evolution of the technology of waste combustion, energy recovery and flue gas treatment allows to redefine the role of the incineration plant as a basic component of integrated waste management systems. Starting with an overview of the evaluation of emission limits and of the new Best Available Techniques (BAT) approach, strongly recommended by the European Union, the paper reports an overview of the stack emission concentrations measured in recent plants in Italy compared to older ones, with special attention to the dioxin issue. Concerning this topic, it is demonstrated that BAT-equipped plants can act as actual dioxin destroyer rather than producers, even when all the fluxes released in the environment (gaseous, solid and liquid residues) are taken into account. The second part of the paper deals with the evolution of the flue gas control technologies of the last 20 years, pointing out the major trends and the future perspectives for ...

305

Effect of the Ge preamorphization dose on boron diffusion and defect evolution in silicon

In this paper, we study the effect of the Ge{sup +} preamorphization dose on boron diffusion and on the thermal evolution of end of range (EOR) defects during annealing. Amorphizations were carried out by implanting Ge{sup +} at 150 keV to doses ranging from 1x10{sup 15} to 8x10{sup 15} ions/cm{sup 2}. Boron was subsequently implanted at 3 keV with a dose of 1x10{sup 14} ions/cm{sup 2}. Rapid thermal annealing (RTA) was performed for various time/temperature combinations in nitrogen ambient. Secondary ion mass spectroscopy (SIMS) and transmission electron microscopy (TEM) were used to study boron diffusion and defect evolution, respectively. We have found that after a given annealing, both the defect size and boron diffusivity are independent on the Ge ion dose. Increasing this dose only results in an increase of the defect density. These results are discussed and definitely show that EOR defects are involved in a quasi-conservative Ostwald ...

2002-01-01

306

Dynamic interpretation of organic-matter maturation and evolution of oil-generative window

In this paper, we study the effect of the Ge"+ preamorphization dose on boron diffusion and on the thermal evolution of end of range (EOR) defects during annealing. Amorphizations were carried out by implanting Ge"+ at 150 keV to doses ranging from 1x10"1"5 to 8x10"1"5 ions/cm"2. Boron was subsequently implanted at 3 keV with a dose of 1x10"1"4 ions/cm"2. Rapid thermal annealing (RTA) was performed for various time/temperature combinations in nitrogen ambient. Secondary ion mass spectroscopy (SIMS) and transmission electron microscopy (TEM) were used to study boron diffusion and defect evolution, respectively. We have found that after a given annealing, both the defect size and boron diffusivity are independent on the Ge ion dose. Increasing this dose only results in an increase of the defect density. These results are discussed and definitely show that EOR defects are involved in a quasi-conservative Ostwald ripening process during annealing. ...

2002-01-01

307

Display concepts for maintaining alarm state overview during unit evolutions

Two phases are recognized in the maturation of organic matter and evolution of the oil-generative window (OGW): (a) a basinal subsidence phase during which potential source rocks undergo burial through a static initial OGW, and maturation is due essentially to increasing temperature with depth, and (b) a postsubsidence phase during which the OGW moves vertically upward through the static sedimentary fill, and maturation is due to time effects. Only the final shallow position of OGW can be defined by geochemical indices of maturity. The hydrocarbon generation sequence progresses from bottom to top, beginning with the lighter hydrocarbons (or even thermogenic gas) at the initial OGW at depth, followed by progressively heavier hydrocarbons as the OGW moves vertically upward. This dynamic model of hydrocarbon generation permits modeling of past positions of OGW relative to basin evolution through interpretation of oil-genesis nomographs. It also ...

1984-08-01

308

Computational models of stellar collapse and core-collapse supernovae

Control room operators rely on the plant annunciation system to alert them to abnormal operating conditions and changes in plant configuration. A key determinant in annunciation system effectiveness is how well the annunciation system displays support Operations staff to staff to maintain a full understanding of the alarm state and ongoing changes under all operating situations. During unit evolutions, current CANDU alarm generation rates can frequently exceed 10 alarms per minute. With existing annunciation displays that list individual alarm changes, the rapid changes in display presentation can exceed an operator's ability to recognize the changes and maintain a full and up-to-date awareness of unit alarm state. This paper describes annunciation display features and concepts for alternative presentation of unit alarm state and changes that can provide improved support to Operations staff during unit evolutions. (author)

2009-07-01

309

A numerical simulation of the evolution and fate of a FRI jet. The case of 3C 31

Core-collapse supernovae are among Nature's most energetic events. They mark the end of massive star evolution and pollute the interstellar medium with the life-enabling ashes of thermonuclear burning. Despite their importance for the evolution of galaxies and life in the universe, the details of the core-collapse supernova explosion mechanism remain in the dark and pose a daunting computational challenge. We outline the multi-dimensional, multi-scale, and multi-physics nature of the core-collapse supernova problem and discuss computational strategies and requirements for its solution. Specifically, we highlight the axisymmetric (2D) radiation-MHD code VULCAN/2D and present results obtained from the first full-2D angle-dependent neutrino radiation-hydrodynamics simulations of the post-core-bounce supernova evolution. We then go on to discuss the new code Zelmani which is based on the open-source HPC Cactus framework and ...

2009-07-01

310

A mechanistic understanding of the formability of magnesium: examining the role of temperature on the deformation mechanisms

The evolution of FRI jets has been long studied in the framework of the FRI-FRII dichotomy. In this paper, we test the present theoretical and observational models via a relativistic numerical simulation of the jets in the radio galaxy 3C 31. We use the parameters derived from the modelling presented by \\cite{lb02a,lb02b} as input parameters for the simulation of the evolution of the source, thus assuming that they have not varied over the lifetime of the source. We simulate about 10 % of the total lifetime of the jets in 3C 31. Realistic density and pressure gradients for the atmosphere are used. The simulation includes an equation of state for a two-component relativistic gas that allows a separate treatment of leptonic and baryonic matter. We compare our results with the modelling of the observational data of the source. Our results show that the bow shock evolves self-similarly at a quasi-constant speed, with slight deceleration by the end ...

2007-01-01

311

THE EVOLUTION OF THE STAR FORMATION RATE OF GALAXIES AT 0.0 #<=# z #<=# 1.2

The possibility of improving the cold formability of wrought magnesium alloys is considered in light of their good hot forming characteristics. Magnesium alloy AZ31B sheet is selected as a model system. Parameters affecting formability, such as strain hardening rate, strain rate sensitivity, and the degree of anisotropy are examined systematically by conducting tensile tests over a range of temperatures (room temperature to 250 C) and strain rates (1 x 10{sup -5} to 0.1 s{sup -1}). The plastic anisotropy and deformation texture evolution are examined in samples aligned with the sheet rolling and transverse directions. Polycrystal plasticity simulations using a viscoplastic self-consistent (VPSC) formulation are used to model the observed anisotropy and texture evolution. The adjustable parameters in the model are the relative critical resolved shear stresses of the dislocation mechanisms known to operate within magnesium. The experimental ...

2003-07-01

312

[Comparative study on the historical evolution of field surgery between China and Russia].

We present the 24 #mu#m rest-frame luminosity function (LF) of star-forming galaxies in the redshift range 0.0 #<=# z #<=# 0.6 constructed from 4047 spectroscopic redshifts from the AGN and Galaxy Evolution Survey of 24 #mu#m selected sources in the Booetes field of the NOAO Deep Wide-Field Survey. This sample provides the best available combination of large area (9 deg"2), depth, and statistically complete spectroscopic observations, allowing us to probe the evolution of the 24 #mu#m LF of galaxies at low and intermediate redshifts while minimizing the effects of cosmic variance. In order to use the observed 24 #mu#m luminosity as a tracer for star formation, active galactic nuclei (AGNs) that could contribute significantly at 24 #mu#m are identified and excluded from our star-forming galaxy sample based on their mid-IR spectral energy distributions or the detection of X-ray emission. Optical emission line diagnostics are considered for ...

2010-08-01

313

Wolf-Rayet stars as gamma-ray burst progenitors

Russian field surgery with its long history and distinctive characteristics has accumulated great experience in the long-time practice of warfare. Chinese field surgery was established and developed on the basis of studying from the Russian model, which opened up new areas of traffic medicine, molecular traumatology and assessment of biological effects on weapon destruction and carried out in-depth research on wound ballistics, blast injury, burns and combined injury etc. through decades of construction with continuous development and innovation, and a series of major achievements have been made in these fields. By making comparative study on the historical evolution, structure system, characteristics of campaigns and development of society between Chinese and Russian field surgery, it can be found that there are great gaps between them and we should strengthen the research for more rapid development. PMID:20510098

2010-03-01

314

British Library Electronic Table of Contents (United Kingdom)

The collapsar scenario for long gamma-ray bursts requires rapidly rotating Wolf-Rayet stars as progenitor stars. We highlight two possible ways out of the dilemma that the strong winds of Wolf-Rayet lead to a fast spin-down. One way is to restrict the duration of the Wolf-Rayet phase to a short time span at the end of the star's evolution. We show that this appears to apply to GRB 021004. The other way is to choose a sub-solar metallicity, thus limiting the Wolf-Rayet wind efficiency. We discuss corresponding stellar evolution models and show that a metallicity limit of about 1/10th solar, as it is required by the models, may be consistent with the empirical gamma-ray burst rate.

2010-01-01

315

Transformation kinetics and microstructures of Ti17 titanium alloy during continuous cooling

Toward unifying the description of meson and baryon properties

We have investigated the microstructure evolutions in the Ti17 near #beta# titanium alloy during heat treatments. The phase transformation has first been studied experimentally by combining X-ray diffraction analysis, electrical resistivity and microscopy observations. From a series of isothermal treatments, a IT diagram has been determined, which takes into account the different morphologies. Then, a Johnson-Mehl-Avrami-Kolmogorov (JMAK) model has been successfully used to describe the phase transformation kinetics during either isothermal or cooling treatments. Finally, the coupling of the JMAK model to the finite element software ZeBuLoN allowed us to investigate the evolution of the spatial distribution of the different morphologies during the cooling of an aircraft engine shaft disk after forging.

2007-03-15

316

Thermo-Hydro Mechanical Characteristics and Processes in the Clay Barrier of a High Level Radioactive Waste Repository. State of the Art Report

We present a Poincare covariant Faddeev equation, which enables the simultaneous prediction of meson and baryon observables using the leading order in a truncation of the Dyson-Schwinger equations that can systematically be improved. The solution describes a nucleon's dressed-quark core. The evolution of the nucleon mass with current-quark mass is discussed. A nucleon-photon current, which can produce nucleon form factors with realistic Q{sup 2} evolution, is described. Axial-vector diquark correlations lead to a neutron Dirac form factor that is negative, with r{sub 1}{sup nu}>r{sub 1}{sup nd}. The proton electric-magnetic form factor ratio falls with increasing Q{sup 2}.

2009-01-15

317

The temporal and spatial patterns and potential evaluation of China?s energy resources development

This document is a summary of the available information on the thermo-hydro-mechanical properties of the bentonite barrier of a high-level radioactive waste repository and of the processes taking place in it during the successive repository operation phases. Mainly the thermal properties, the volume change processes (swelling and consolidation), the permeability and the water retention capacity are analysed. A review is made of the existing experimental knowledge on the modification of the these properties by the effect of temperature, water salinity, humidity and density of the bentonite, and their foreseen evolution as a consequence of the processes expected in the repository. The compiled evolution refers mostly to the FEBEX (Spain), the MX-80 (USA) and the FoCa (France) bentonite, considered as reference barrier materials in several European disposal concepts. (Author) 102 refs.

2004-05-01

318

British Library Electronic Table of Contents (United Kingdom)

The issue of China?s energy supply security is not only the key problem which affects China?s rapid and sustainable development in the 21st century, but also the one which international attention focuses on. Based on the notable characteristic of spatial imbalance between energy production and consumption in China, this paper takes the evolution of China?s primary energy resources development(excluding hydropower) from 1949 to 2007 as the study object, with the aim to sum up the evolutive characteristics and laws of China?s energy resources development in the past nearly 60 years. Then, based on comprehensive considerations of coal?s, oil?s and natural gas?s basic reserves, qualities, geological conditions, production status, and ecological service function of every province, this paper ad...

2010-01-01

319

The number and metallicities of the most metal-poor stars

The Huqf Supergroup of Oman: Basin development and context for Neoproterozoic glaciation

Simple, one-zone models for inhomogeneous chemical evolution of the Galactic halo are used to predict the number fraction of zero-metallicity, Population III stars, which currently is empirically estimated at < 4e-4. These analytic models minimize the number of free parameters, highlighting the most fundamental constraints on halo evolution. There are disagreements of at least an order of magnitude between observations and predictions in limiting cases for both homogeneous Simple Model and Simple Inhomogeneous Model (SIM). Hence, this demonstrates a quantitative, unambiguous discrepancy in the observed and expected fraction of Population III stars. We explore how the metallicity distribution of the parent enrichment events f(z_0) drives the SIM and predictions for the Population III fraction. The SIM shows that the previously-identified "high halo" and "low halo" populations are consistent with a continuous evolutionary progression, and ...

2003-01-01

320

British Library Electronic Table of Contents (United Kingdom)

The Huqf Supergroup of the Sultanate of Oman provides important information on the geological evolution of the Arabian?Persian Gulf region during a protracted period of continental dispersal and reassembly on the periphery of the Gondwanan supercontinent during the Neoproterozoic, and also provides important constraints on the nature of extreme climate swings during this critical period in the evolution of Earth's biosphere. The Huqf Supergroup spans the period ca. 725?540?Ma, and is composed of three groups. The Abu Mahara Group (ca. 725 to ca.ca. 547?540?Ma), which is known mostly from the subsurface, comprises carbonates, evaporites and organic-rich shales, with interbedded ashes, deposited in a large number of N?S trending troughs and platforms.The three groups of the Huqf Supergroup c...

2007-01-01

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321

Symbiotic N2 fixation by legumes growing in pots. 2. Uptake of VN-labelled NO3 , C2H2 reduction and H2 evolution by Trifolium subterraneum L. , Medicago truncatula Gaertn. and Acacia dealbata Link

Study on the structural evolution of modified phenol-formaldehyde resin adhesive for the high-temperature bonding of graphite

The objectives of this study were to estimate symbiotic nitrogen fixation by two common pasture legumes, Trifolium subterraneum L. and Medicago truncatula Gaertn., and an Australian native legume, Acacia dealbata Link, growing in pots using an indirect isotopic method. This method was also used to calibrate the C2H2 reduction assay of the intact plants. In addition, hydrogen evolution was measured in an attempt to explain the variations in C2H2:N2 ratios between the species. 25 refs.; 1 figure; 4 tabs.

1983-01-01

322

Status and progress in ion implantation technology for semiconductor device manufacturing

A novel adhesive for carbon materials composed of phenol-formaldehyde resin, boron carbide and fumed silica, was prepared. The adhesive property of graphite joints bonded by the above adhesive treated at high-temperatures was tested. Results showed that the adhesive was found to have outstanding high-temperature bonding properties for graphite. The adhesive structure was dense and uniform even after the graphite joints were heat-treated at 1500 deg. C. Bonding strength was 17.1 MPa. The evolution of adhesive structure was investigated. The results indicated that the addition of the secondary additive, fumed silica, improved the bonding performance greatly. Borosilicate phase with better stability was formed during the heat-treatment process, and the volume shrinkage was restrained effectively, which was responsible for the satisfactory high-temperature bonding performance of graphite.

2006-01-01

323

Simulation of a storage ring Free Electron Laser with mapping algorithm for distribution functions

Rapid growth in implant applications in the fabrication of semiconductors has encouraged a dramatic increase in the range of energies, beam currents and ion species used. The challenges of a wider energy range, higher beam currents, continued reduction in contamination, improved angle integrity and larger substrates have motivated the development of many innovations. Advanced processes in submicron device production uses up to twenty implantation steps. Thus the outstanding growth of this industry has led to the evolution of a thriving business of hundreds of implantation equipment systems each year with very specific requirements. The present paper reviews the principal process requirements which resulted in the evolution of the equipment technology, and describes the recent trends in the ion implanter technology all three principal categories: high current, medium current and high energy. (author)

1998-12-08

324

Recent observations on the evolution of secondary-phase particles in zircaloy-2 under irradiation in a BWR to high burn-up

A model for the simulation of the time dependent behavior and the analysis of the equilibrium of the coupled system of storage ring and Free Electron Laser (FEL) is presented. The analysis comprises both amplifier and oscillator FEL. Bunch lengthening and energy widening due to wake forces are taken into account in a self-consistent way. The method is based on a mapping algorithm for means and correlations of the electron distribution function, pioneered by K. Hirata. The evolution of the laser field in the oscillator FEL is described by K. Hirata. The evolution of the laser field in the oscillator FEL is described by supermodes. The model is used to simulate an FEL in a small 500 MeV storage ring with 100 m circumference. Typical values for the output power, spatial, and spectral characteristics of the emitted radiation are presented.

1991-05-06

325

Quantitative analysis of X-Ray Microtomography images of metal powders in the course of sintering

The influence of radiation on the corrosion of the fuel claddings in a Light Water Reactor (LWR) has been the subject of many investigations, and different aspects of the overall phenomena have been studied by different techniques. Analysis of the evolution of Secondary-Phase Particles (SPPs) for different periods of immersion of the cladding in the reactor enables the rate of corrosion to the structure of the material to be correlated. In the case of Zircaloy-2 in a Boiling Water Reactor (BWR), SPPs are dissolved under irradiation, and their dissolution affects the rate of oxidation and other correlated phenomena. In recent studies, the Zircaloy-2 in claddings loaded in the Leibstadt BWR are analysed after one, three and five cycles. Results are presented, and give an account of the changes which occurred in the materials under irradiation. (authors)

2000-07-01

326

Photoluminescence Decay of Irradiated Herbs

In situ X-Ray microtomography offers new opportunities for analysing sintering mechanisms since it allows 3D observation of the microstructural evolution of the powder all along a sintering cycle. With synchrotron radiation at ESRF, a 3D image with a resolution of 2 {mu}m can be obtained in about one minute. In addition to the visual examination of the images, relevant microstructural parameters can be measured through quantitative image analysis using recently developed tools. In this paper the results obtained with two materials, loose copper powder and compacted steel powder, are resumed. For copper powder, the dispersion of local parameters such as particle co-ordination number and porosity is investigated. Concerning steel compacts, data about pore morphology evolution and on local strains provides clues for understanding the anisotropic shrinkage of such compacts. (authors)

2005-07-01

327

Photoluminescence Decay of Irradiated Herbs

Thermoluminescence of inorganic dust extract from herbs and spices has been demonstrated to be a useful method to discriminate irradiated food products as well as to estimate the total dose exposure. The time evolution of infrared stimulated luminescence has been systematically investigated in potassium feldspar and albite minerals subjected to different doses of gamma irradiation (ranging from 0 to 8 kGy). Experimental results reveal a 300-600 nm signal which is greatly intensified for irradiated samples, following the same irradiation dose dependence observed in thermoluminescence. The luminescence intensity disappears after few seconds of illumination, following a time evolution which is proportional to (1 + Bt){sup -P}. The influence of both B and P factors upon the irradiation dose has been systematically analysed. (author)

1999-07-01

328

On the evolution of supernova remnants: Pt. 2

Thermoluminescence of inorganic dust extract from herbs and spices has been demonstrated to be a useful method to discriminate irradiated food products as well as to estimate the total dose exposure. The time evolution of infrared stimulated luminescence has been systematically investigated in potassium feldspar and albite minerals subjected to different doses of gamma irradiation (ranging from 0 to 8 kGy). Experimental results reveal a 300-600 nm signal which is greatly intensified for irradiated samples, following the same irradiation dose dependence observed in thermoluminescence. The luminescence intensity disappears after few seconds of illumination, following a time evolution which is proportional to (1 + Bt)"-"P. The influence of both B and P factors upon the irradiation dose has been systematically analysed. (author)

1998-07-05

329

ON THE PROGENITOR AND EARLY EVOLUTION OF THE TYPE II SUPERNOVA 2009kr

Supernova explosions within wind-driven bubbles are studied with 2D hydrodynamical calculations. Two different density distributions for the ejecta are considered: (i) a smooth, unfragmented power-law stratification, and (ii) a fragmented distribution. As in 1D models, the presence of the shell of interstellar swept-up matter causes the rapid evolution of the remnant to the radiative phase. The main 2D effects, for both fragmented and unfragmented ejecta, include: (i) substantial chaotic deviations from a purely radial flow in the remnant interior, (ii) efficient turbulent mixing between the ejecta and the shocked wind, resulting in homogenization of the former wind cavity, and (iii) severe distortion of the wind-driven shell by cooling and Rayleigh-Taylor instabilities. (author).

330

Neutron star evolution and emission

We identify a source coincident with SN 2009kr in Hubble Space Telescope pre-explosion images. The object appears to be a single point source with an intrinsic color V - I = 1.1 #+-# 0.25 and M_V = -7.6 #+-# 0.6. If this is a single star, it would be a yellow supergiant of log L/L _s_u_n #approx# 5.1 and a mass of 15"+"5 _-_4 M _s_u_n. The spatial resolution does not allow us yet to definitively determine if the progenitor object is a single star, a binary system, or a compact cluster. We show that the early light curve is similar to a Type IIL SN, but the prominent H#alpha# P-Cygni profiles and the signature of the end of a recombination phase are reminiscent of a Type IIP. The evolution of the expanding ejecta will play an important role in understanding the progenitor object.

2010-05-10

331

Morphology evolution of Ir-Nb-X (X = Hf, Ta, or Ti) ternary alloys

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors investigated the evolution and radiation characteristics of individual neutron stars and stellar systems. The work concentrated on phenomena where new techniques and observations are dramatically enlarging the understanding of stellar phenomena. Part of this project was a study of x-ray and gamma-ray emission from neutron stars and other compact objects. This effort included calculating the thermal x-ray emission from young neutron stars, deriving the radio and gamma-ray emission from active pulsars and modeling intense gamma-ray bursts in distant galaxies. They also measured periodic optical and infrared fluctuations from rotating neutron stars and search for high-energy TeV gamma rays from discrete celestial sources.

1997-08-01

332

Morphological characteristics and medium-term evolution of the beaches between Ceuta and Cabo Negro (Morocco)

The microstructure evolution of nine samples from three Ir-base ternary systems, Ir-Nb-Hf, Ir-Nb-Ta, and Ir-Nb-Ti, was investigated by microstructure observation using scanning electron microscopy (SEM), composition map-analysis using electron probe microscopy analysis (EPMA), and phase determination using X-ray diffraction (XRD) patterns. The fcc/L1{sub 2} two-phase structure was detected in all the samples. Lattice misfits between fcc and L1{sub 2} phases were calculated. Ir-Nb-Ta and Ir-Nb-Ti alloys exhibited a microstructure quite similar to that of Ni-base superalloys, and the cuboidal L1{sub 2} precipitates in Ir-Nb-Ta and Ir-Nb-Ti alloys could maintain up to 1900 {sup o}C.

2007-01-31

333

British Library Electronic Table of Contents (United Kingdom)

This work presents the results of a combined study on the beach morphology and the evolution at short- and medium-term of the littoral between Ceuta and Cabo Negro (Morocco). It is an interesting sector showing a great increase of human occupation and coastal structures. The monitoring program allowed for the reconstruction of the beach morphological behavior and the seasonal changes. The studied beaches presented reflective profiles recording little seasonality, with the most notable morphological changes being strictly related to storms. Surf Similarity and Surf Scaling parameters highlighted the existence of intermediate and reflective beach states, characterized by plunging breakers. Aerial photographs and a satellite image have been geo-referenced and elaborated with GIS tools to reco...

2007-01-01

334

Modelling of density limit phenomena in toroidal helical plasmas

Microstructural evolution during hot rolling of an AZ31 Mg alloy

The physics of density limit phenomena in toroidal helical plasmas based on an analytic point model of toroidal plasmas is discussed. The combined mechanism of the transport and radiation loss of energy is analyzed, and the achievable density is derived. A scaling law of the density limit is discussed. The dependence of the critical density on the heating power, magnetic field, plasma size and safety factor in the case of L-mode energy confinement is explained. The dynamic evolution of the plasma energy and radiation loss is discussed. Assuming a simple model of density evolution, of a sudden loss of density if the temperature becomes lower than critical value, then a limit cycle oscillation is shown to occur. A condition that divides the limit cycle oscillation and the complete radiation collapse is discussed. This model seems to explain the density limit oscillation that has been observed on the W7-AS stellarator. (author)

2000-03-01

335

Longer exaggerated male genitalia confer defensive sperm-competitive benefits in an earwig

The microstructural evolution of a AZ31 Mg alloy during hot rolling has been investigated using optical microscopy and texture (macro and micro) analysis as the main characterization tools. In particular, the differences between the microstructure obtained by unidirectional rolling (UR) and cross rolling (CR) are studied. Significant twinning activity is observed in both cases. Additionally, after cross rolling, a rather heterogeneous microstructure develops, with scattered regions populated by very fine grains. The strong basal fiber texture of the as-received material remains present after both hot rolling schemes. The impossibility to obtain accurate EBSD measurements within the twinned regions suggests that significant localized deformation takes place in those areas. Thus, these regions become preferential sites for the onset of recrystallization due to the increase in the local strain energy. (orig.)

2003-07-01

336

British Library Electronic Table of Contents (United Kingdom)

As evidence mounts that male genitalia can affect relative fertilisation success, the role that sexual selection has played in the rapid and divergent evolution of genitalia is becoming increasingly recognized. Unfortunately, the limited functional understanding of these complex structures and their interactions with the female reproductive tract often limit interpretation regarding their evolution. Here, we address this issue using the earwig Euborellia brunneri, where both the male intromittent organ and the female spermatheca are highly exaggerated in length yet structurally simple. In a double mating design, we use the sterile male technique to study how sperm precedence patterns are affected by male genital length, male age, and the size of the male sperm storage organ, the seminal ve...

2011-01-01

337

Industry churning and the evolution of cities: Evidence for Germany

British Library Electronic Table of Contents (United Kingdom)

In this paper we show that the recent model by Gilles Duranton [Duranton, G., 2007. Urban evolutions: The fast, the slow, and the still. American Economic Review 97, 197-221] performs remarkably well in replicating the city size distribution of West Germany, much better than the simple rank-size rule known as Zipfs law. The main mechanism of this theoretical framework is the "churning" of industries across cities. Little is known in urban economics about the determinants of local industry turnover so far. We present an empirical analysis of the excess churning index for West German cities, which describes the strength of intra-city industry reallocations over time. We find that urban growth and industry turnover are not notably correlated: Some, but not all fast-growing cities have notably...

2008-01-01

338

High-resolution sequence stratigraphic framework and its characteristic. Case study of C-P coal measures in Hebei

Extragalactic Planetary Nebulae: Observational Challenges & Future Prospects

The framework of time-sequence stratigraphy was established according to the point of view of high-resolution sequence stratigraphy. The development characteristic of the sequence, the distribution pattern of strata, the basin evolution and filling, and the relationship between variations of base level and coal accumulation of epicontinental basin were expounded based on the base-level cycles. The result shows that the C-P coal measures in Hebei is a series of basin deposit of inner epicontinental sea. The formation and evolution and sedimentation of the basin is intimately related to the changes of the basin base-level, which controls the development of the coal-accumulation, forming a clear coal-bearing sequence in the cycle. 9 refs., 3 figs.

2001-07-01

339

Experimental investigations of plasma bullets

The study of extragalactic planetary nebulae (EPN) is a rapidly expanding field. The advent of powerful new instrumentation such as the PN spectrograph has led to an avalanche of new EPN discoveries both within and between galaxies. We now have thousands of EPN detections in a heterogeneous selection of nearby galaxies and their local environments, dwarfing the combined galactic detection efforts of the last century. Key scientific motivations driving this rapid growth in EPN research and discovery have been the use of the PNLF as a standard candle, as dynamical tracers of their host galaxies and dark matter and as probes of Galactic evolution. This is coupled with the basic utility of PN as laboratories of nebula physics and the consequent comparison with theory where population differences, abundance variations and star formation history within and between stellar systems informs both stellar and galactic evolution. Here we pose some of the ...

2004-01-01

340

Evolution of lattice strain in Ti-6Al-4V during tensile loading at room temperature

Recently several investigators reported on various means of generating cold plasma jets at atmospheric pressure. More interestingly, these jets turned out to be not continuous plasmas but trains of small high velocity plasma packets/bullets. However, until now little is known of the nature of these 'bullets'. Here we present experimental insights into the physical and chemical characteristics of bullets. We show that their time of initiation, their velocity and the distance they travel are directly dependent on the value of the applied voltage. We also show that these bullets can be controlled by the application of an external electric field. Using an intensified charge coupled device camera we report on their geometrical shape, which was revealed to be 'donut' shaped, therefore giving an indication that solitary surface ionization waves may be responsible for the creation of these bullets. In addition, using emission spectroscopy, we follow the evolution of ...

2009-03-07

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341

Evolution of drought severity and its impact on corn in the Republic of Moldova

The evolution of intergranular lattice strains in a textured, forged bar (Bar) sample of the #alpha# - #beta# titanium alloy Ti-6Al-4V has been characterised using in situ X-ray diffraction. A two-phase elastic-plastic self-consistent (EPSC) model has been developed to rationalise the results. Of the orientations analysed, it is found that the #left brace#2 0 0#right brace# #beta# orientation is the most compliant and that load partitions to this orientation during plasticity. The results from the bar material have then been used to predict the response of unidirectionally rolled plate (UD) Ti-6Al-4V. It is predicted that the residual lattice strains in the #left brace#101-bar0#right brace# and #left brace#112-bar0#right brace# orientations will be significantly higher in the UD material.

2008-12-01

342

British Library Electronic Table of Contents (United Kingdom)

Droughts in Moldova were evaluated using meteorological data since 1955 and a long time series (1891?2009). In addition, yields for corn (Zea mays L.), a crop widely grown in Moldova, were used to demonstrate drought impact. The main aim is to propose use of the S i (S i-a and S i-m) drought index while discussing its potential use in studying the evolution of drought severity in Moldova. Also, a new multi-scalar drought index, the standardized precipitation?evapotranspiration index (SPEI), is tested for the first time in identifying drought variability in Moldova while comparing it with the commonly used standardized precipitation index (SPI). S i-m, SPI, SPEI, and S i-a indices show an increasing tendency toward more intensive and prolonged severely dry and extremely dry summer months. D...

2011-01-01

343

Effect of Kerr nonlinearity on an Airy beam

Dynamical evolution of a scalar field coupling to Einstein's tensor in the Reissner-Nordstroem black hole spacetime

The effect of Kerr nonlinearity on an Airy beam is investigated by using the nonlinear Schroedinger equation. Based on the moments method, the evolution of the Airy beam width in the rms sense is analytically described. Numerical simulations indicate that the central parts of the major lobe of the Airy beam initially give rise to radial compression during propagation in a focusing medium, even though the rms beam width broadens. The partial collapse of the center parts of the major lobe of the beam appear below the threshold for a global collapse. The evolutions of the field distributions of the Airy beams are different during propagation in different Kerr media while the beams still travel along the parabolic trajectory just as the beam propagates in free space.

2010-10-01

344

Dependence of the evolution of the cavity radiation of a coherently pumped correlated emission laser on dephasing and phase fluctuation

We study the dynamical evolution of a scalar field coupling to Einstein's tensor in the background of a Reissner-Nordstroem black hole. Our results show that the coupling constant #eta# imprints in the wave dynamics of a scalar perturbation. In the weak coupling, we find that with the increase of the coupling constant #eta# the real parts of the fundamental quasinormal frequencies decrease and the absolute values of imaginary parts increase for fixed charge q and multipole number l. In the strong coupling, we find that for l#not =#0 the instability occurs when #eta# is larger than a certain threshold value #eta#_c which deceases with the multipole number l and charge q. However, for the lowest l=0, we find that there does not exist such a threshold value and the scalar field always decays for arbitrary coupling constant.

2010-10-15

345

Dense and diffuse gas in dynamically active clouds

Analysis of the dynamics of the cavity radiation of a coherently pumped correlated emission laser is presented. The phase fluctuation and dephasing are found to affect the time evolution of the two-mode squeezing and intensity of the cavity radiation significantly. The intensity and degree of the two-mode squeezing increase at early stages of the process with time, but this trend changes rapidly afterwards. It is also shown that they increase with phase fluctuation and dephasing in the strong driving limit, however the situation appears to be opposite in the weak driving limit. This essentially suggests that the phase fluctuation and dephasing weaken the coherence induced by a strong driving mechanism so that the spontaneous emission gets a chance. The other important aspect of the phase fluctuation, in this regard, is the relaxation of the time at which the maximum squeezing is manifested as well as the time in which the radiation remains in a squeezed state.

2010-01-01

346

Assessment of the efficiency of short term countermeasures following a severe accident on a PWR

We investigate the chemical and observational implications of repetitive transient dense core formation in molecular clouds. We allow a transient density fluctuation to form and disperse over a period of 1 Myr, tracing its chemical evolution. We then allow the same gas immediately to undergo further such formation and dispersion cycles. The chemistry of the dense gas in subsequent cycles is similar to that of the first, and a limit cycle is reached quickly (2 - 3 cycles). Enhancement of hydrocarbon abundances during a specific period of evolution is the strongest indicator of previous dynamical history. The molecular content of the diffuse background gas in the molecular cloud is expected to be strongly enhanced by the core formation and dispersion process. Such enhancement may remain for as long as 0.5 Myr. The frequency of repetitive core formation should strongly determine the level of background molecular enhancement. We also convolve the ...

2006-01-01

347

A spectre haunts evolution: Haeckel, Heidegger, and the all-too-human history of biology.

In case of a severe nuclear accident at a PWR plant, countermeasures will be initiated in the short term by authorities to reduce the consequences of the atmospheric radioactive releases on the neighbouring population. Various factors influence the level of protection afforded by countermeasures. For instance, a too late intervention would lead to a Jack of efficiency in terms of dose reduction if the actual evolution of the accident is not considered. Thus, implementation of countermeasures should be optimized. In general, the projected doses (those without countermeasure) are compared with those expected when a particular countermeasure or strategy is implemented. In this paper, an in-depth analysis associates the kinetics of the release with the corresponding evolution of the dosimetric efficiency of countermeasures. This is done at different times in the short term of the accident and for various distances from the plant. Results are ...

2001-07-01

348

A complete census of AGN and their hosts from optical surveys?

Since The Meaning of Evolution (1992), Robert J. Richards has argued that modern evolutionary theory is rooted in late 18th-century Romantic science. The publication of The Tragic Sense of Life (2009) provides a fitting occasion to evaluate how this perspective revises the standard history of biological thought. This essay focuses on three aspects of Richards's attempt to rehabilitate the reputation of German Naturphilosophie: (1) the identification of Romantic strains in Charles Darwin's portrait of evolutionary history; (2) the demonstration that any attempt to treat Ernst Haeckel as a "pseudo-Darwinian" inevitably renders Darwin himself a "pseudo-Darwinian"; and (3) the denial of Haeckel's alleged responsibility for the rise of Nazi racial hygiene. This article examines Richards's case for clearing Haeckel's name, as well as the subsequent (slanderous) charge from Daniel Gasman that Richards is guilty of whitewashing the Haeckelian roots of the Holocaust. ...

2010-01-01

349

The role of high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in the diagnosis of preoperative and postoperative complications caused by acquired cholesteatomas; CT und MRT des erworbenen Cholesteatoms: Prae- und postoperative Bildgebung

Large optical surveys provide an unprecedented census of galaxies in the local Universe, forming an invaluable framework into which more detailed studies of objects can be placed. But how useful are optical surveys for understanding the co-evolution of black holes and galaxies, given their limited wavelength coverage, selection criteria, and depth? In this conference paper I present work-in-progress comparing optical and mid-IR diagnostics of three "unusual" low redshift populations (luminous Seyferts, dusty Balmer-strong AGN, ULIRGs) with a set of ordinary star-forming galaxies from the SDSS. I address the questions: How well do the mid-infrared and optical diagnostics of star formation and AGN strength agree? To what extent do optical surveys allow us to include extreme, dusty, morphologically disturbed galaxies in our "complete" census of black hole-galaxy co-evolution?

2010-01-01

350

High-resolution magnetic resonance imaging: three-dimensional trabecular bone architecture and biomechanical properties.

The role of high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in the diagnosis of preoperative and postoperative complications caused by acquired cholesteatomas will be described in this paper. The pre- and postoperative imaging of the temporal bone was performed with HRCT and MRI. HRCT and MRI were performed in the axial and coronal plane. MRI was done with T2 weighted and T1 weighted sequences both before and after the intravenous application of contrast material. All imaging findings were confirmed clinically or surgically. The preoperative cholesteatoma-caused complications depicted by HRCT included bony erosions of the ossicles, scutum, facial canal in the middle ear, tympanic walls including the tegmen tympani, and of the labyrinth. The preoperative cholesteatoma-caused complications depicted by MRI included signs indicative for labyrinthitis, and brain abscess. Postoperative HRCT depicted bony erosions caused by recurrent ...

2003-03-01

351

Dura thickening adjacent to intracranial tumors on MRI. Histologically correlation; Duraverdickung am Rand intrakranieller, duranaher Raumforderungen in der MRT. Histologische Korrelation

The purpose of this study was to use high-resolution magnetic resonance (MR) imaging combined with image analysis to investigate the three-dimensional (3D) trabecular structure, anisotropy, and connectivity of human vertebral, femoral, and calcaneal specimens. The goal was to determine whether: (a) MR-derived measures depict known skeletal-site-specific differences in architecture and orientation of trabeculae; (b) 3D architectural parameters combined with bone mineral density (BMD) improve the prediction of the elastic modulus using a fabric tensor formulation; (c) MR-derived 3D architectural parameters combined with BMD improve the prediction of strength using a multiple regression model, and whether these results corresponded to the results obtained using higher resolution depictions of trabecular architecture. A total of 94 specimens (12 x 12 x 12 mm cubes) consisting of trabecular bone only were obtained, of which there were 7 from the calcaneus, 15 from distal femur, 47 from the ...

1998-05-01

352

Determination of cartilage thickness in the ankle joint. MRT (1,5 T) comparative anatomical study; Bestimmung der Knorpeldicke am oberen Sprunggelenk. Eine MRT(1,5 T)-anatomische Vergleichsstudie

Purpose: With intracranial tumors a flat, contrast-enhancing, probably dural structure adjacent to the tumor can occasionally be observed on gadolinium-DTPA enhanced MR images. Therefore we have attempted to evaluate a tumor infiltration of this enthancement on MRI. Material and Methods: This study included 50 patients. 19 patients had a dural thickening at the tumor base (13 meningiomas and 6 metastases), while 31 patients did not (12 meningiomas and 19 metastases). Studies included plane T{sub 2}-weighted spin echo (SE) images as well as T{sub 1}-weighted axial, coronal, or sagittal plains with and without contrast agent. Histopathological examinations, were done on the tumor base adjacent to the dura mater. Results: 7 of 12 meningiomas showed a meningeal thickening on MRI with histopathologically proven tumor infiltration as did also 5 of 6 metastases. But 3 of 12 meningiomas and 15 of 19 metastases without dural thickening at the tumor base also showed tumor ...

1997-11-01

353

Wide cross-species aminoacyl-tRNA synthetase replacement in vivo: yeast cytoplasmic alanine enzyme replaced by human polymyositis serum antigen.

Purpose: The aim of this study was to evaluate the accuracy of MRI in the measurement of cartilage thickness of the ankle joint in comparison to pathologic and histologic specimens. Patients and methods: The ankle joints of four fresh cadaver feet were imaged on a 1.5 T MR-unit in the coronal plane. Standard T{sub 1}-weighted spin echo (SE) and a T{sub 1}-weighted 3D-GE (FLASH-3D) sequence with fat saturation were applied. Following MR imaging, the talus was explanted and cut parallel to the MR images for macroscopic evaluation and histologic specimens were prepared. MRI measurements of the cartilage thickness of the talus were carried out in two ways: Without and with consideration of a transition zone of intermediate signal intensity between hyperintense cartilage and hypointense cortical bone. The data were compared with the anatomic specimens as the gold standard expressing the difference as a percentage value. On histologic specimens thickness of deep ...

1997-04-01

354

Because of variations in tRNA sequences in evolution, tRNA synthetases either do not acylate their cognate tRNAs from other organisms or execute misacylations which can be deleterious in vivo. We report...Full Text Available

1995-05-23

355

What masses for Cepheids

The triaxial motion in Mo isotopes

To understand the evolution of giant stars, it is important to pin down the masses for Cepheids. The 7- to 10-day bump Cepheids imply lower than evolutionary mass (60%). Recent theoretical work, though, indicates that for Cepheids with periods of 15 to 16 days, the best understanding of the light curves results from using evolutionary masses.

356

The triaxial motion in Mo isotopes

The nuclear shapes of transitional Mo isotopes are calculated by means of a model based on the cranking approximation and the Strutinksy method. The recent experimental results of the high-spin spectroscopy and lifetime measurement of [sup 87]Mo are studied in detail and explained by the evolution of the [gamma]-deformation with the quasiparticle configurations. The shape calculations with the modified-harmonic-oscillator potential give a critical neutron number N [>=] 47 for the spherical shape of the Mo isotopes. (orig.)

1993-11-22

357

The market efficiency in the stock markets

The nuclear shapes of transitional Mo isotopes are calculated by means of a model based on the cranking approximation and the Strutinksy method. The recent experimental results of the high-spin spectroscopy and lifetime measurement of "8"7Mo are studied in detail and explained by the evolution of the #gamma#-deformation with the quasiparticle configurations. The shape calculations with the modified-harmonic-oscillator potential give a critical neutron number N #>=# 47 for the spherical shape of the Mo isotopes. (orig.).

358

The holographic principle and the language of genes

We study the temporal evolution of the market efficiency in the stock markets using the complexity, entropy density, standard deviation, autocorrelation function, and probability distribution of the log return for Standard and Poor's 500 (S&P 500), Nikkei stock average index, and Korean composition stock price index (KOSPI). Based on the microscopic spin model, we also find that these statistical quantities in stock markets depend on the market efficiency.

2007-01-01

359

The formation of counterrotating cores in elliptical galaxies

We show that the holographic principle in quantum gravity imposes a strong constraint on life. The degrees of freedom of an organism can be estimated according to the theory of Boolean networks, which is constrained by the entropy bound. Hence we can explain the languages in protein sequences or in DNA sequences. The overall evolution of biological complexity can be illustrated. And some general properties of protein length distributions can be explained by a linguistic mechanism.

2008-01-01

360

The dipole picture in DIS: saturation and heavy quarks

The mechanism proposed by Kormendy (1984) for the formation of counterrotating cores in elliptical galaxies is investigated using self-consistent numerical simulations of mergers between a high- and a low-luminosity elliptical galaxies. The conditions for a counterrotation to appear are determined, observational properties of the remnants are described, and the evolution of the structural and kinematic parameters of the larger galaxy is analyzed. It is shown that a counterrotation results only when the merging orbits are retrograde, due to a large change in the secondary spin during the merger. 36 refs.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

361

The building tomorrow and after..; Le batiment demain et apres-demain..

We discuss the description of the proton structure function within the dipole factorization framework. We parameterize the forward dipole amplitude to account for saturation as predicted by the small-x QCD evolution equations. Contrarily to previous models, the saturation scale does not decrease when taking heavy quarks into account. We show that the same dipole amplitude also allows to reproduce diffractive data and exclusive vector meson production.

2008-04-07

362

Tachyons in compact spaces

During its jubilee, the French building technical and scientific centre (CSTB) has organized a colloquium about the future tendencies of buildings evolution in the 20 forthcoming years: autonomy in energy production and wastes or effluents management, reduction of water consumption and management of water, hot water production and space heating, bio-sensors for the management of indoor air-quality, control of noise environment using active acoustic systems etc.. (J.S.)

1998-01-01

363

THE EVOLUTION OF THE KINEMATICS OF NEBULAR SHELLS IN PLANETARY NEBULAE IN THE MILKY WAY BULGE

We discuss condensations of closed string tachyons localized in compact spaces. Time evolution of an on-shell condensation is naturally related to the worldsheet RG flow. Some explicit tachyonic compactifications of Type II string theory is considered, and some of them are shown to decay into supersymmetric theories known as the little string theories.

2005-05-01

364

Symbiotic star BF Cygni from 1965 to 1970

We study the line widths in the [O III]#lambda#5007 and H#alpha# lines for two groups of planetary nebulae in the Milky Way bulge based upon spectroscopy obtained at the Observatorio Astronomico Nacional in the Sierra San Pedro Martir (OAN-SPM) using the Manchester Echelle Spectrograph. The first sample includes objects early in their evolution, having high H#beta# luminosities, but [O III]#lambda#5007/H#beta# < 3. The second sample comprises objects late in their evolution, with He II #lambda#4686/H#beta#>0.5. These planetary nebulae represent evolutionary phases preceding and following those of the objects studied by Richer et al. in 2008. Our sample of planetary nebulae with weak [O III]#lambda#5007 has a line width distribution similar to that of the expansion velocities of the envelopes of asymptotic giant branch stars and shifted to systematically lower values as compared to the less evolved objects studied by Richer et al. The ...

2010-06-10

365

Surface photometry and the structure of elliptical galaxies

Sixteen spectra of the symbiotic star BF Cygni covering the period 1965-- 1970 were investigated. Variations of the line intensities, the Balmer decrements, the color, and electronic temperatures are given. Approximate values of the electron density were deduced in order to derive an order of magnitude for the sizes of the emitting regions of BF Cygni. A crude stratification and evolution model is proposed. (auth)

1973-03-01

366

Spin evolution in wind-fed X-ray binaries

Surface photometry of bulges and elliptical galaxies is reviewed. The properties of cores and nuclei as revealed by improvements in seeing and the use of CCDs are examined, and newly discovered structural details such as dust, shells, and dynamical subsystems which show the importance of accretion events in galactic evolution are addressed. Improved constraints on galaxy formation resulting from better measurements of parameter scaling laws are discussed, and accurate measurements of departures from elliptical isophotes and of color gradients obtained with CCDs are considered.

367

Size of a bouncing mixmaster universe

Global angular momentum balance suggests that the neutron stars in Be/X-ray binaries are not spinning in equilibrium. This requires an X-ray lifetime ''approx <'' 10"5 yr, and suggests that there are many 'dead' Be/X-ray binaries in the Galaxy. Some of these may be turned up as millisecond radio pulsars with Be star companions. (author).

368

Sequence analysis of two alleles reveals that intra-and intergenic recombination played a role in the evolution of the radish fertility restorer (Rfo)

An analysis is given of the evolution of a massive scalar field in a closed mixmaster universe of Bianchi type IX. Although the scalar field violates the strong energy condition, the probability of the model ''bouncing'' at a very early time is infinitesimally small; of the order of the ratio of the minimum to maximum sizes of the universe approx. 10/sup -40/.

1980-01-15

369

Relationship between microstructural evolution and low cycle fatigue behaviour at 550/sup 0/C of alloy 800 grade 2

BackgroundLand plant genomes contain multiple members of a eukaryote-specific gene family encoding proteins with pentatricopeptide repeat (PPR) motifs. Some PPR proteins were shown...Full Text Available

370

Radiation accidents with multi-organ failure in the United States.

In this study, deformation modes and precipitations have been characterized in test pieces made of alloy 800, grade 2 hyper-hardened state and age-conditioned for 3000 h at 550/sup 0/C, used for steam generator tubes of the Super Phenix Reactor, after continuous fatigue and fatigue-relaxation tests in the oligocyclic range. This microstructural study has provided an interpretation of the fatigue behaviour of the material.

1989-01-01

371

Physics of thermal gaseous nebulae

Only a small number of radiation accidents in the United States have been severe enough to result in multi-organ failure (MOF). Medical details of selected medical misadministration and criticality cases are reviewed, with an emphasis on pathophysiology. The four criticality cases are particularly relevant for analysis of MOF, since medical treatment was supportive and did not appreciably alter the clinical evolution of radiation injury. PMID:15975871

2005-01-01

372

Optimizing semiconductor devices by self-organizing particle swarm

Much of the material presented in this book derived originally from the series ''Physical Processes in Gaseous Nebulae'' initiated at the Harvard College Observatory in the 1930's. The subject of gaseous nebulae, which offers opportunities for studies of stellar evolution, should be of interest to atomic physicists, spectroscopists, plasma experts, and to observers and theoreticians alike for the study of attenuated ionized gases.

1984-01-01

373

Null field method in wave diffraction problems

A self-organizing particle swarm is presented. It works in dissipative state by employing the small inertia weight, according to experimental analysis on a simplified model, which with fast convergence. Then by recognizing and replacing inactive particles according to the process deviation information of device parameters, the fluctuation is introduced so as to driving the irreversible evolution process with better fitness. The testing on benchmark functions and an application example for device optimization with designed fitness function indicates it improves the performance effectively.

2005-01-01

374

British Library Electronic Table of Contents (United Kingdom)

Diffraction by an impermeable scatterer in ?3 with a Dirichlet boundary condition is considered. It is shown that the null field equation is equivalent to the original diffraction problem. The general theoretical constructions are illustrated by analyzing the excitation of a sphere by a point source. The evolution of the residual of the null field equation as the scatterer surface is approached by an auxiliary surface is estimated.

2011-01-01

375

Non-uniqueness in conformal formulations of the Einstein constraints

Monte Carlo molecular simulations: improving the statistical efficiency of samples with the help of artificial evolution algorithms; Simulations moleculaires de Monte Carlo: amelioration de l'efficacite statistique de l'echantillonnage grace aux algorithmes d'evolution artificielle

Standard methods in non-linear analysis are used to show that there exists a parabolic branching of solutions of the Lichnerowicz-York equation with an unscaled source. We also apply these methods to the extended conformal thin sandwich formulation and show that if the linearised system develops a kernel solution for sufficiently large initial data then we obtain parabolic solution curves for the conformal factor, lapse and shift identical to those found numerically by Pfeiffer and York. The implications of these results for constrained evolutions are discussed.

2006-01-01

376

Microstructure evolution and strength-reduction in area balance of ultrafine-grained steels processed by warm caliber rolling

Molecular simulation aims at simulating particles in interaction, describing a physico-chemical system. When considering Markov Chain Monte Carlo sampling in this context, we often meet the same problem of statistical efficiency as with Molecular Dynamics for the simulation of complex molecules (polymers for example). The search for a correct sampling of the space of possible configurations with respect to the Boltzmann-Gibbs distribution is directly related to the statistical efficiency of such algorithms (i.e. the ability of rapidly providing uncorrelated states covering all the configuration space). We investigated how to improve this efficiency with the help of Artificial Evolution (AE). AE algorithms form a class of stochastic optimization algorithms inspired by Darwinian evolution. Efficiency measures that can be turned into efficiency criteria have been first searched before identifying parameters that could be optimized. Relative ...

2002-03-01

377

British Library Electronic Table of Contents (United Kingdom)

Ultrafine grained steels with different carbon contents were produced through warm caliber rolling and evaluated for their stress-strain behavior along with the reduction in area. It was found that the reduction in area-tensile strength balance is far better than the conventional ferrite+pearlite steels and even superior to bainitic steels for all materials tested in the present study.

2006-01-01

378

Microstructural evolution in several casts of alloy 800 during creep tests

Magnetization and magnetostriction curves for highly magnetostrictive materials

The creep behaviour of different casts of Alloy 800, supplied by different sources, has been determined in multispecimen furnaces at 650, 750 and 800"0C and at different stress levels up to about 14,000 hs; the environment was initially helium and then air. The microstructural investigations were carried out by transmission electron microscopy. (Auth.).

379

Inflation in a renormalizable cosmological model and the cosmic no-hair conjecture

The macroscopic behavior of magnetostrictive materials results from domain evolutions occurring at a microscopic scale. The author shows how to compute magnetization and magnetostriction curves by appraising the behavior of the underlying microstructures. The method hinges on an averaging device (Young measures), which allows one to pass from the microscopic to the macroscopic scale. He takes into account the kinematical constraints on the accommodation of elastic effects, and he highlights the role of material symmetry in the selection of energetically optimal microstructures.

1994-12-31

380

Inflation in a renormalizable cosmological model and the cosmic no-hair conjecture

The possibility of having inflation in a renormalizable cosmological model is investigated. The cosmic no-hair conjecture is proved to hold for all Bianchi types except Bianchi type IX. By the use of a conformal transformation on the metric we show that these models are equivalent to the ones described by the Einstein-Hilbert action for gravity minimally coupled to a set of scalar fields with inflationary potentials. Henceforth, we prove that inflationary solutions behave as attractors in solution space, making it a natural event in the evolution of such models.

1989-05-15

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381

Improved Conservation Properties for Particle-in-cell Simulations with Kinetic Electrons

The possibility of having inflation in a renormalizable cosmological model is investigated. The cosmic no-hair conjecture is proved to hold for all Bianchi types except Bianchi type IX. By the use of a conformal transformation on the metric we show that these models are equivalent to the ones described by the Einstein-Hilbert action for gravity minimally coupled to a set of scalar fields with inflationary potentials. Henceforth, we prove that inflationary solutions behave as attractors in solution space, making it a natural event in the evolution of such models.

382

ITER council proceedings: 1995

It is shown that a simple algorithm which exactly segregates between adiabatic and non-adiabatic electrons in particle-in-cell simulations of drift modes yields excellent conservation properties (e.g. particle number, energy) compared to the conventional df scheme. The removal of the free streaming term in the evolution of the marker weight is shown to be responsible for the improved linear and nonlinear properties of the simulated plasma.

2003-06-19

383

Global existence for the Euler-Maxwell system

Records of the 8. ITER Council Meeting (IC-8), held on 26-27 July 1995, in San Diego, USA, and the 9. ITER Council Meeting (IC-9) held on 12-13 December 1995, in Garching, Germany, are presented, giving essential information on the evolution of the ITER Engineering Design Activities (EDA) and the ITER Interim Design Report Package and Relevant Documents. Figs, tabs.

2008-11-01

384

Genomic sequence for human prointerleukin 1 beta: possible evolution from a reverse transcribed prointerleukin 1 alpha gene.

The Euler-Maxwell system describes the evolution of a plasma when the collisions are important enough that each species is in a hydrodynamic equilibrium. In this paper we prove global existence of small solutions to this system set in the whole three-dimensional space, by combining the space-time resonance method, dispersive estimates, localization estimates and energy estimates. An important novelty is that we can prove a very slow growth of high derivatives even with a nonintegrable decay by reiterating the energy estimate.

2011-01-01

385

Genetic Characteristics, Coreceptor Usage Potential and Evolution of Nigerian HIV-1 Subtype G and CRF02_AG Isolates

We have isolated the human prointerleukin 1 (proIL-1) beta gene from leukocyte and fetal liver libraries. The nucleotide sequence and its gene organization reveals that the proIL-1 beta gene is composed...Full Text Available

1986-10-24

386

Galactic evolution of D and "3He including stellar production of "3He

HIV-1 CRF02_AG and subtype G (HIV-1G) account for most HIV infections in Nigeria, but their evolutionary trends have not been well documented. To better elucidate the dynamics of the epidemic in Nigeria...Full Text Available

387

Field guide to the binary stars

New stellar models which track the production and destruction of "3He (and D) have been evolved for a range of stellar masses (0.65#<=#M/M_c_i_r_c_l_e_-_d_o_t#<=#100), metallicities (0.01#<=#Z/Z_c_i_r_c_l_e_-_d_o_t#<=#1), and initial (main-sequence) "3He mass fractions (10"-"5#<=#X_3_,_M_S#<=#10"-"3). Armed with the "3He yields from these stellar models we have followed the evolution of D and "3He using a variety of chemical evolution models with and without infall of primordial or processed material. Production of new "3He by the lower mass stars overwhelms any reasonable primordial contributions and leads to predicted abundances in the presolar nebula and/or the present interstellar medium in excess of the observationally inferred values. This result, which obtains even for zero primordial D and "3He, and was anticipated by Rood, Steigman, ampersand Tinsley is insensitive to the choice of chemical ...

388

Evolution of the chromospheres and winds of low- and intermediate-mass giant stars

For most of the history of binary star astronomy, systems have been classified largely on the basis of how they were discovered and qualitative appearance of their spectra and light curves. Present understanding of single and double star evolution has now progressed to the point where most of the classes previously identified, and some new ones, can be arranged into evolutionary sequences, depending primarily on the initial masses and separation of the component stars.

1983-05-12

389

Evolution of longitudinal modes in low voltage FEL

Results are presented of an empirical analysis of the global thermodynamical requirements of the winds in the outer atmospheres of a representative sample of red giant stars of low- and intermediate-mass range. Results indicate that the mass-loss rates in these stars are not strongly dependent on the actual physical processes driving the winds. It is suggested that nonlinear processes act to regulate wind energy fluxes. Possible mechanisms responsible for the chromospheric heating and the mass loss in the low- and intermediate-mass giant stars are discussed. 151 refs.

390

Evolution of health information management and information technology in emergency medicine.

A low voltage FEL operating at 130 kV which can be run cw with a continuous electron beam current level up to 12 mA has been constructed for the X-Band microwave range (8-12 GHz). In this poster, we will report on the dependence on time, after the electron beam is switched on, of the growth and competition of those longitudinal modes in the cavity having nett gain.

1995-12-31

391

Evolution of a cluster of innate immune genes (?-defensins) along the ancestral lines of chicken and zebra finch

The implementation of information technology will continue to have important effects on the practice of emergency medicine. Patient registration and tracking systems, telemedicine electronic order entry systems, and the advent of electronic health records are some examples of applications that influence patient care in emergency departments. We review the literature regarding information technology advances in emergency medicine and outline the important role that emergency physicians play in developing and implementing a national health information technology strategy. PMID:16712540

2006-06-01

392

Evolution of a bifunctional enzyme: 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase.

BackgroundAvian β-defensins (AvBDs) represent a group of innate immune genes with broad antimicrobial activity. Within the chicken genome, previous work identified 14 AvBDs...Full Text Available

393

Evolution of Hepatitis B Virus in a Chronic HBV-Infected Patient over 2 Years

The bifunctional rat liver enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (ATP:D-fructose-6-phosphate 2-phosphotransferase/D-fructose-2,6-bisphosphate 2-phosphohydrolase, EC 2.7.1.105/EC...Full Text Available

1989-12-01

394

Energy intensity, CO{sub 2} emissions and the environmental Kuznets curve. The Spanish case

Mutations in full-length HBV isolates obtained from a chronic HBV-infected patient were evaluated at three time points: 1 day, 6 months, and 31 months. While 5 nucleotides variation, and an 18 bp...Full Text Available

2011-01-01

395

Energy consumption scenarios for the fertilizer industry; Cenarios e consumo de energia na industria de fertilizantes

This article analyses the role of energy intensity and the relationship between CO{sub 2} emissions and primary energy in order to explain the evolution of CO{sub 2} emissions by unit of real GDP. It also distinguishes two different meanings of CO{sub 2} emissions Kuznets curve hypothesis: the weak and the strong sense. It considers the case of Spain in the period 1972-1997 as an example in which there is not any evidence supporting this hypothesis in either sense. (author)

2001-06-01

396

Electrochemical stability of silicon/carbon composite anode for lithium ion batteries

This paper shows the characteristics of the fertilizer production park of the State of Minas Gerais, Brazil, mainly in the aspects of energy consumption and energy sources used in the production process of the various kinds of fertilizers and by-products. A scenario including the fertilizer production evolution was made, relating this future production with the future energy consumption of this sector. 7 figs., 2 tabs.

1991-12-31

397

Dynamical evolution and molecular abundances of interstellar clouds

Silicon/carbon composite anode materials were prepared by pyrolyzing the phenol-formaldehyde resin (PFR) mixed with silicon and graphite powders. Scanning electron microscopic (SEM) observation showed that the morphology stability of the composite electrodes can be retained during cycling. A structure evolution mechanism is proposed to illuminate the enhancement of cycleability of the composite electrode. The composite used as anode material for lithium ion batteries possesses a reversible capacity of over 700 mAh/g.

2007-04-20

398

Cooperative spontaneous emission from two different atoms

Dynamical models are presented that start with interstellar gas in an initial diffuse state and consider their gravitational collapse and the formation of dense cores. Frozen-in tangled magnetic fields are included to mimic forces that might oppose gravitational contraction and whose effectiveness may increase with increasing core densities. Results suggest the possibility that dense cloud cores may be dynamically evolving ephemeral objects, such that their lifespan at a given core density decreases as that density increases. 66 refs.

399

Computed tomography - old ideas and new technology

The total radiation rate, angular distribution of the emitted energy and photon correlations of the cooperative spontaneous radiation from two atoms with different resonance frequencies and spontaneous decay rates are calculated. Contrary to the case of two identical atoms oscillations appear in the total radiation rate and the spatial distribution of the total number of emitted photons differs from the single-atom radiation pattern. The effect of the dipole-dipole near-field interaction on the time evolution of the atomic system is discussed. (author).

1986-01-01

400

Comparison between NO_x Evolution Mechanisms of Wild-Type and nr₁ Mutant Soybean Leaves ¹

Several recently introduced 'new' techniques in computed tomography - iterative reconstruction, gated cardiac CT, multiple-source, and dual-energy CT - actually date back to the early days of CT. We review the historic origins and evolution of these techniques, which may provide some insight into the latest innovations in commercial CT systems. (orig.)

2011-03-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

401

Characterization of polluted sites. Assessment of pollutant behaviour and transfer in mediums; Caracterisation des sites pollues. L`evaluation du comportement et du transfert des polluants dans les milieux

The nr₁ soybean (Glycine max [L.] Merr.) mutant does not contain the two constitutive nitrate reductases, one of which is responsible for enzymic conversion of nitrite to...Full Text Available

1990-05-01

402

Chaotic behaviour in higher-order gravity theories

After a presentation of methods and tools for the basic and extensive characterization of polluted sites and the study of evolution and transfer of current organic pollutants in the ground, the example of the rehabilitation of an old Rhone-Poulenc site (at Chauny, France) polluted with metals and arsenic, is described: soil and aquifer diagnosis, risk analysis and determination of migration schemes

1996-12-31

403

Chaotic behaviour in higher-order gravity theories

We show that the chaotic dynamical behaviour displayed by diagonal Bianchi type IX metrics in general relativity does not occur on approach to the singularity in higher-order lagrangian theories of gravity. However, chaotic behaviour does occur in the more general non-diagonal type IX models in these theories. An interpretation of these results in terms of the hamiltonian potential picture of the type IX evolution is given. (orig.).

1989-11-30

404

Australian Studies in Europe and the Omnipresent Elephant

We show that the chaotic dynamical behaviour displayed by diagonal Bianchi type IX metrics in general relativity does not occur on approach to the singularity in higher-order lagrangian theories of gravity. However, chaotic behaviour does occur in the more general non-diagonal type IX models in these theories. An interpretation of these results in terms of the hamiltonian potential picture of the type IX evolution is given. (orig.).

405

DEFF Research Database (Denmark)

Australian Studies has to undergo a transformation from its overtly literary focus to a more interdisciplinary approach, if it is to have a viable future. Rather than seeing this as a moment of unproductive stalemate, the article argues for the advantages in developing such a new focus. Also the article considers the historical evolution of Australian Studies in Europe.

2009-01-01

406

Approaches to Modeling Coupled Flow and Reaction in a 2-D Cementation Experiment

Analytical determination of the dimensions and evolution with current of the ion-emitting jet in liquid-metal ion sources

Porosity evolution at reactive interfaces is a key process that governs the evolution and performances of many engineered systems that have important applications in earth and environmental sciences. This is the case, for example, at the interface between cement structures and clays in deep geological nuclear waste disposals. Although in a different transport regime, similar questions arise for permeable reactive barriers used for biogeochemical remediation in surface environments. The COMEDIE project aims at investigating the coupling between transport, hydrodynamics and chemistry when significant variations of porosity occur. The present work focuses on a numerical benchmark used as a design exercise for the future COMEDIE-2D experiment. The use of reactive transport simulation tools like Hytec and Crunch provides predictions of the physico-chemical evolutions that are expected during the future experiments in laboratory. ...

2008-04-01

407

An ADP proposal to study the formation and evolution of dust-embedded clusters. Final report

The apex dimensions and length are calculated as a function of current for the ion-emitting jet in liquid-metal ion sources (LMIS). The results agree well with observations. Since the final expressions are analytical, they give more insight into the fundamental mechanisms involved than do numerical calculations. Some implications of the model are discussed concerning focused ion beam (FIB) systems employing LMIS. (author).

1991-12-14

408

Amazon.com: Products tagged with intelligence

Using high resolution and high sensitivity IRAS data at 12 and 25 microns low mass stars were studied which have recently formed in the Ophiuchus, Corona Australis, and IC1396 dark clouds. The successful application of these techniques to the Rho Ophiuchi infrared cluster is briefly described. The status of research performed is also presented.

409

Adiabatic quantum computing with phase modulated laser pulses

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410

AGB (asymptotic giant branch): Star evolution

Implementation of quantum logical gates for multilevel systems is demonstrated through decoherence control under the quantum adiabatic method using simple phase modulated laser pulses. We make use of selective population inversion and Hamiltonian evolution with time to achieve such goals robustly instead of the standard unitary transformation language. (letter to the editor)

2005-09-23

411

A numerical weather prediction model--Computational aspects on the CRAY-1

Asymptotic giant branch stars are red supergiant stars of low-to-intermediate mass. This class of stars is of particular interest because many of these stars can have nuclear processed material brought up repeatedly from the deep interior to the surface where it can be observed. A review of recent theoretical and observational work on stars undergoing the asymptotic giant branch phase is presented. 41 refs.

1987-01-01

412

2015 Plan. Project 1: methodology and planning process of the Brazilian electric sector expansion

This paper presents a case study in the design and implementation of a numerical weather prediction model on a supercomputer (CRAY-1). Following a historical introduction to the evolution of the model, the governing equations of the model are presented and the numerical solution of these forecast equations is described. A brief tutorial on the architecture of the CRAY-1 is presented with a discussion of how it affects the choice of algorithms and code design of the model. A summary of the advantages gained by use of the vector aspects of the CRAY-1 is included.

1984-01-01

413

EVOLUTION OF MASSIVE PROTOSTARS VIA DISK ACCRETION

The Planning Process of Brazilian Electric Sector Expansion, their normative aspects, instruments, main agents and the planning cycles are described. The methodology of expansion planning is shown, with the interactions of several study areas, electric power market and the used computer models. The forecasts of methodology evolution is also presented. (C.G.C.).

414

WITNESSING THE KEY EARLY PHASE OF QUASAR EVOLUTION: AN OBSCURED ACTIVE GALACTIC NUCLEUS PAIR IN THE INTERACTING GALAXY IRAS 20210+1121

Mass accretion onto (proto-)stars at high accretion rates M-dot_*> 10"-"4 M_s_u_n yr"-"1 is expected in massive star formation. We study the evolution of massive protostars at such high rates by numerically solving the stellar structure equations. In this paper, we examine the evolution via disk accretion. We consider a limiting case of 'cold' disk accretion, whereby most of the stellar photosphere can radiate freely with negligible backwarming from the accretion flow, and the accreting material settles onto the star with the same specific entropy as the photosphere. We compare our results to the calculated evolution via spherically symmetric accretion, the opposite limit, whereby the material accreting onto the star contains the entropy produced in the accretion shock front. We examine how different accretion geometries affect the evolution of massive protostars. For cold disk accretion at 10"-"3 ...

2010-09-20

415

Vibrational and Rotational Sequences in "1"0"1Mo And "1"0"3","4Ru Studied via Multinucleon Transfer Reactions

We report the discovery of an active galactic nucleus (AGN) pair in the interacting galaxy system IRAS 20210+1121 at z = 0.056. An XMM-Newton observation reveals the presence of an obscured (N _H #approx# 5 x 10"2"3 cm"-"2), Seyfert-like (L _2_-_1_0_k_e_V = 4.7 x 10"4"2 erg s"-"1) nucleus in the northern galaxy, which lacks unambiguous optical AGN signatures. Our spectral analysis also provides strong evidence that the IR-luminous southern galaxy hosts a Type 2 quasar embedded in a bright starburst emission. In particular, the X-ray primary continuum from the nucleus appears totally depressed in the XMM-Newton band as expected in the case of a Compton-thick absorber, and only the emission produced by Compton scattering ('reflection') of the continuum from circumnuclear matter is seen. As such, IRAS 20210+1121 seems to provide an excellent opportunity to witness a key, early phase in the quasar evolution predicted by the theoretical models of quasar activation by ...

2010-10-20

416

Utilization of CTR to measure the evolution of electron-beam microbunching in a self-amplified spontaneous emission (SASE) free-electron laser (FEL)

The near-yrast states of "1"0"1_4_2Mo_5_9 and "1"0"3","4_4_4 Ru_5_9_,_6_0 have been studied following their population via heavy-ion multinucleon transfer reactions between a "1"3"6Xe beam and a thin, self-supporting "1"0"0Mo target. The ground state sequence in "1"0"4Ru can be understood as demonstrating a simple evolution from a quasi-vibrational structure at lower spins to statically deformed, quasi-rotational excitation involving the population of a pair of low-#OMEGA# h_1_1_/_2 neutron orbitals. The effect of the decoupled h_1_1_/_2 orbital on this vibration-to-rotational evolution is demonstrated by an extension of the ''E-GOS'' prescription to include odd-A nuclei. The experimental results are also compared with self-consistent Total Routhian Surface calculations which also highlight the polarising role of the highly aligned neutron h_1_1_/_2 orbital in these nuclei. (author)

2005-04-01

417

Utilization of CTR to measure the evolution of electron-beam microbunching in a self-amplified spontaneous emission (SASE) free-electron laser (FEL)

We report on the first measurements of the z-dependent evolution of electron-beam microbunching as revealed through coherent transition radiation (CTR) measurements in a visible self-amplified spontaneous emission free-electron laser experiment. The increase in microbunching was detected by tracking the growth of the visible CTR signals as generated from insertable metal mirrors/foils after each of the last three undulators. The same optical imaging diagnostics that were used to track the z-dependent intensity of the undulator radiation (UR) were also used to track the electron beam/CTR information. Angular distribution, beam size, and intensity data were obtained after each of the last three undulators in the five-undulator series, and spectral information was obtained after the last undulator. The exponential growth rate of the CTR was found to be very similar to that of the UR and consistent with simulations using the code GENESIS.

2002-07-01

418

Type Ia supernova science 2010-2020

We report on the first measurements of the z-dependent evolution of electron-beam microbunching as revealed through coherent transition radiation (CTR) measurements in a visible self-amplified spontaneous emission free-electron laser experiment. The increase in microbunching was detected by tracking the growth of the visible CTR signals as generated from insertable metal mirrors/foils after each of the last three undulators. The same optical imaging diagnostics that were used to track the z-dependent intensity of the undulator radiation (UR) were also used to track the electron beam/CTR information. Angular distribution, beam size, and intensity data were obtained after each of the last three undulators in the five-undulator series, and spectral information was obtained after the last undulator. The exponential growth rate of the CTR was found to be very similar to that of the UR and consistent with simulations using the code GENESIS.

2001-12-21

419

Travelling wave solutions to the Kuramoto-Sivashinsky equation

In the next decade Type Ia supernovae (SNe Ia) will be used to test theories predicting changes in the Dark Energy equation of state with time. Ultimately this requires a dedicated space mission like JDEM. SNe Ia are mature cosmological probes --- their limitations are well characterized, and a path to improvement is clear. Dominant systematic errors include photometric calibration, selection effects, reddening, and population-dependent differences. Building on past lessons, well-controlled new surveys are poised to make strides in these areas: the Palomar Transient Factory, Skymapper, La Silla QUEST, Pan-STARRS, the Dark Energy Survey, LSST, and JDEM. They will obviate historical calibrations and selection biases, and allow comparisons via large subsamples. Some systematics follow from our ignorance of SN Ia progenitors, which there is hope of determining with SN Ia rate studies from 0

2009-01-01

420

The radiation hardening and microstructural defect evolution in ion irradiated Fe-Cr alloys with irradiation temperature

Combining the approaches given by Baldwin [Baldwin D et al. Symbolic computation of exact solutions expressible in hyperbolic and elliptic functions for nonlinear PDEs. J Symbol Comput 2004;37:669-705], Peng [Peng YZ. A polynomial expansion method and new general solitary wave solutions to KS equation. Comm Theor Phys 2003;39:641-2] and by Schuermann [Schuermann HW, Serov VS. Weierstrass' solutions to certain nonlinear wave and evolution equations. Proc progress electromagnetics research symposium, 28-31 March 2004, Pisa. p. 651-4; Schuermann HW. Traveling-wave solutions to the cubic-quintic nonlinear Schroedinger equation. Phys Rev E 1996;54:4312-20] leads to a method for finding exact travelling wave solutions of nonlinear wave and evolution equations (NLWEE). The first idea is to generalize ansaetze given by Baldwin and Peng to find elliptic solutions of NLWEEs. Secondly, conditions used by Schuermann to find physical (real and bounded) ...

2007-08-01

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421

The physical properties of extra-solar planets

Generally, neutron, ion and electron Irradiations cause a substantial amount of hardening and significantly alter the deformation behavior of metals and alloys at relatively low irradiation temperatures. A radiation hardening is caused by the formation of microstructural defects such as dislocation loops, voids and precipitates under irradiation. Therefore, it is important to have a better knowledge of the irradiation induced microstructural defects under irradiation condition. As a part of the National mid- and long-term atomic energy R and D program, we are dealing with the radiation hardening behavior in Fe-Cr binary alloy. Fe-Cr binary alloy is a base alloy of Ferritic/Martensitic steel(F/M steel) planning to use for the Gen IV nuclear system. In this work, we investigated the radiation hardening and microstructural defect evolution in ion irradiated Fe-Cr alloys with irradiation temperature using nano-indentation measurement and transmission electron ...

2009-05-01

422

The mixmaster universe in Horava-Lifshitz gravity

Tremendous progress in the science of extrasolar planets has been achieved since the discovery of a Jupiter orbiting the nearby Sun-like star 51 Pegasi in 1995. Theoretical models have now reached enough maturity to predict the characteristic properties of these new worlds, mass, radius, atmospheric signatures, and can be confronted with available observations. We review our current knowledge of the physical properties of exoplanets, internal structure and composition, atmospheric signatures, including expected biosignatures for exo-Earth planets, evolution, and the impact of tidal interaction and stellar irradiation on these properties for the short-period planets. We discuss the most recent theoretical achievements in the field and the still pending questions. We critically analyze the different solutions suggested to explain abnormally large radii of a significant fraction of transiting exoplanets. Special attention is devoted to the recently discovered ...

2010-01-01

423

The mixmaster universe in Horava-Lifshitz gravity

We consider spatially homogeneous (but generally non-isotropic) cosmologies in the recently proposed Horava-Lifshitz gravity and compare them to those of general relativity using Hamiltonian methods. In all cases, the problem is described by an effective point particle moving in a potential well with exponentially steep walls. Focusing on the closed-space cosmological model (Bianchi type IX), the mixmaster dynamics is now completely dominated by the quadratic Cotton tensor potential term for a very small volume of the universe. Unlike general relativity, where the evolution toward the initial singularity always exhibits chaotic behavior with alternating Kasner epochs, the anisotropic universe in Horava-Lifshitz gravity (with parameter lambda > 1/3) is described by a particle moving in a frozen potential well with fixed (but arbitrary) energy E. Alternating Kasner epochs still provide a good description of the early universe for very large E, but the ...

2010-02-21

424

The evolution of habitable zones during stellar lifetimes and its implications on the search for extraterrestrial life

We consider spatially homogeneous (but generally non-isotropic) cosmologies in the recently proposed Horava-Lifshitz gravity and compare them to those of general relativity using Hamiltonian methods. In all cases, the problem is described by an effective point particle moving in a potential well with exponentially steep walls. Focusing on the closed-space cosmological model (Bianchi type IX), the mixmaster dynamics is now completely dominated by the quadratic Cotton tensor potential term for a very small volume of the universe. Unlike general relativity, where the evolution toward the initial singularity always exhibits chaotic behavior with alternating Kasner epochs, the anisotropic universe in Horava-Lifshitz gravity (with parameter #lambda# > 1/3) is described by a particle moving in a frozen potential well with fixed (but arbitrary) energy E. Alternating Kasner epochs still provide a good description of the early universe for very large E, but the ...

2010-02-21

425

The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III

A stellar evolution computer model has been used to determine changes in the luminosity L and effective temperature T(e) of single stars during their time on the main sequence. The range of stellar masses investigated was from 0.5 to 1.5 times that of the Sun, each with a mass fraction of metals (metallicity, Z) from 0.008 to 0.05. The extent of each star's habitable zone (HZ) has been determined from its values of L and T(e). These stars form a reference framework for other main sequence stars. All of the 104 main sequence stars known to have one or more giant planets have been matched to their nearest stellar counterpart in the framework, in terms of mass and metallicity, hence closely approximating their HZ limits. The limits of HZ, for each of these stars, have been compared to its giant planet(s)'s range of strong gravitational influence. This allows a quick assessment as to whether Earth-mass planets could exist in stable orbits within the HZ of such systems, ...

2003-01-01

426

THE EVOLUTION OF CLOUD CORES AND THE FORMATION OF STARS

The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Ly{alpha} forest, and a radial velocity search for planets around {approx}8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes 5-band imaging of roughly 5200 deg{sup 2} in the Southern Galactic Cap, bringing the total footprint of the SDSS imaging to 14,555 deg{sup 2}, or over a third of the Celestial Sphere. All the imaging data have been reprocessed with an improved sky-subtraction algorithm and a final, self-consistent recalibration and flat-field determination. This release also includes all data from the second phase of the Sloan Extension for Galactic Understanding and Evolution (SEGUE-2), ...

2011-01-01

427

Surface brightness and effective radius for elliptical galaxies

For a number of starless cores, self-absorbed molecular line and column density observations have implied the presence of large-amplitude oscillations. We examine the consequences of these oscillations on the evolution of the cores and the interpretation of their observations. We find that the pulsation energy helps support the cores and that the dissipation of this energy can lead toward instability and star formation. In this picture, the core lifetimes are limited by the pulsation-decay timescales, dominated by non-linear mode-mode coupling, and on the order of #approx =# few x 10"5-10"6 yr. Notably, this is similar to what is required to explain the relatively low rate of conversion of cores into stars. For cores with large-amplitude oscillations, dust continuum observations may appear asymmetric or irregular. As a consequence, some of the cores that would be classified as super-critical may be dynamically stable when oscillations are taken into account. Thus, ...

2010-09-20

428

Stress-assisted crystallisation in anodic titania

Seeing convolved two-dimensional de Vaucouleurs profiles have been fitted to digital images of the brightest elliptical galaxies in two nearby groups of galaxies and three clusters of galaxies with redshifts in the range 0.06 to 0.15. The digital images were created by scanning electronographic plates obtained by the use of several versions of the RGO electronographic camera. The linear relation between effective surface brightness #mu#/sub e/ and the logarithm of the effective radius r/sub e/, first discovered by Kormendy to be valid for nearby elliptical galaxies, is found to be equally valid for the largest and brightest galaxies in rich clusters of galaxies. The apparent universal nature of that relation indicates that the same type of processes might have been involved during the formation of all ellipticals from cD galaxies in clusters to fainter ellipticals in small groups. It is suggested that the (I/sub e/,r/sub e/) relation is not changed by the expected dynamical ...

429

Set of equations for stress-mediated evolution of the nonequilibrium dopant-defect system in semiconductor crystals

Research highlights: ? Correlations between microstructure and internal stress during Ti anodising are established. ? Large internal compressive stresses are accumulated in the film during anodising upto 12 V. ?A transition from compressive to tensile stress is observed when the cell voltage exceeds 12 V. ? At 40 V, the oxide films consist of two regions with different compositions and microstructures. Crystallisation of amorphous to anatase TiO2 contributes to the compressive stress relaxation. - Abstract: The relationship between the microstructural and internal stress evolution during Ti anodising is discussed. Samples anodised galvanostatically to 12 V and 40 V, corresponding to different stages of the internal stress evolution, were examined by in-plane and cross-section transmission electron microscopy. Electron diffraction patterns have been complemented with stoichiometry data obtained from energy loss near edge structure spectra. The ...

2011-04-01

430

Set of equations for stress-mediated evolution of the nonequilibrium dopant-defect system in semiconductor crystals

A set of equations describing a stress-mediated evolution of the nonequilibrium dopant-defect system has been derived and analyzed. Together with coupled diffusion of dopant atoms and point defects, we consider the drift of all mobile species in different charge states, namely vacancies, self-interstitials, and pairs 'dopant atom-point defect', in the field of stress. It has been shown that stresses may affect the diffusion of dopant atoms mainly in two ways: (1) directly, due to the drift of the pairs in the field of stress; (2) indirectly, by the formation of nonuniform defect distribution due to the drift of point defects. On this basis, various features of doping processes, such as phenomena of 'uphill' impurity diffusion near the surface (within the framework of the first or second mechanisms) and the peculiarities of high concentration phosphorus diffusion (due to the second mechanism), can be explained. Numerical ...

2004-11-17

431

Self-Interacting Dark Matter Halos and the Gravothermal Catastrophe

A set of equations describing a stress-mediated evolution of the nonequilibrium dopant-defect system has been derived and analyzed. Together with coupled diffusion of dopant atoms and point defects, we consider the drift of all mobile species in different charge states, namely vacancies, self-interstitials, and pairs 'dopant atom-point defect', in the field of stress. It has been shown that stresses may affect the diffusion of dopant atoms mainly in two ways: (1) directly, due to the drift of the pairs in the field of stress; (2) indirectly, by the formation of nonuniform defect distribution due to the drift of point defects. On this basis, various features of doping processes, such as phenomena of 'uphill' impurity diffusion near the surface (within the framework of the first or second mechanisms) and the peculiarities of high concentration phosphorus diffusion (due to the second mechanism), can be explained. Numerical computations of high concentration phosphorus ...

2004-11-17

432

Radiation decoherence, state vector collapse and QED nonequivalent representations

We study the evolution of an isolated, spherical halo of self-interacting dark matter (SIDM) in the gravothermal fluid formalism. We show that the thermal relaxation time, $t_r$, of a SIDM halo with a central density and velocity dispersion of a typical dwarf galaxy is significantly shorter than its age. We find a self-similar solution for the evolution of a SIDM halo in the limit where the mean free path between collisions, $\\lambda$, is everywhere longer than the gravitational scale height, $H$. Typical halos formed in this long mean free path regime relax to a quasistationary gravothermal density profile characterized by a nearly homogeneous core and a power-law halo where $\\rho \\propto r^{-2.19}$. We solve the more general time-dependent problem and show that the contracting core evolves to sufficiently high density that $\\lambda$ inevitably becomes smaller than $H$ in the innermost region. The core undergoes secular collapse to a ...

2002-01-01

433

Probing isolated compact remnants with microlensing

The state vector evolution in the interaction of initial measured pure state with collective quantum system or the field with a very large number of degrees of freedom N is analysed in a nonperturbative QED formalism. As the example the measurement of the electron final state scattered on nucleus or neutrino is considered.In the nonperturbative field theory the complete manifold of the system states is nonseparable i.e. is described by tensor product of infinitely many independent Hilbert spaces. The interaction of this system with the measured state can result in the final states which belong to different Hilbert spaces which corresponds to different values of some classical observables,i.e. spontaneous symmetry breaking occurs. Interference terms (IT) between such states in the measurement of any Hermitian observable are infinitely small and due to it the final pure states can't be distinguished from the mixed ones, characteristic for the state collapse. The ...

1996-01-01

434

Photocatalytic activities of AgSbO3 under visible light irradiation

We consider isolated compact remnants (ICoRs), i.e. neutrons stars and black holes that do not reside in binary systems and therefore cannot be detected as X-ray binaries. ICoRs may represent $\\sim\\,5$ percent of the stellar mass budget of the Galaxy, but they are very hard to detect. Here we explore the possibility of using microlensing to identify ICoRs. In a previous paper we described a simulation of neutron star evolution in phase space in the Galaxy, taking into account the distribution of the progenitors and the kick at formation. Here we first reconsider the evolution and distribution of neutron stars and black holes adding a bulge component. From the new distributions we calculate the microlensing optical depth, event rate and distribution of event time scales, comparing and contrasting the case of ICoRs and "normal stars". We find that the contribution of remnants to optical depth is slightly lower than without kinematics, owing to ...

2010-01-01

435

British Library Electronic Table of Contents (United Kingdom)

A novel visible light sensitive photocatalyst, AgSbO3 was prepared by a conventional solid-state reaction method. This oxide belonging to a cubic-pyrochlore structure can absorb visible light with wavelength up to about 480nm. From the band structure calculation, we found that the top of the valence band consists of the hybridized Ag 4d and O 2p orbitals and the bottom of the conduction band mainly consists of the Ag 5s and the Sb 5s orbitals. Photocatalytic activities were evaluated using O2 evolution from an aqueous silver nitrate solution and decomposition of gaseous 2-propanol under visible light irradiation. We found that AgSbO3 shows a higher O2 evolution activity than WO3 and 2-propanol can be mineralized by the AgSbO3 photocatalysis under visible light irradiation.

2008-01-01

436

Performance of Alcator C-Mod core Thomson scattering system

Optimization algorithm for linearity enhancement in the design of continuous-time sigma-delta modulators

Design of the Alcator C-Mod Thomson scattering (TS) diagnostic is discussed and the results of the measurements are presented. The TS system has six spatial channels with observation volumes evenly distributed between the midplane and the edge of the plasma. Each channel is capable of measuring the electron density in the range N{sub e}=5{times}10{sup 19}{endash}5{times}10{sup 21} m{sup {minus}3} and temperature from T{sub e}=200 eV to 10 keV. A 30 Hz, 1.5 J per pulse Nd-YAG laser is employed allowing the measurements of evolution of T{sub e} and N{sub e} profiles during plasma shot. A laser beam position control and feedback system provides for the beam alignment stability and reliable electron density measurements. Examples of the core density and temperature profiles measured at different stages of the plasma evolution are discussed. {copyright} {ital 1999 American Institute of Physics.}

1999-01-01

437

Optimal control of the free boundary in a two-phase Stefan problem

This paper proposes an optimization algorithm to reduce the distortion produced in the loop-filter of Continuous-Time Sigma-Delta Modulators. The aim of the algorithm is to find the loop-filter implementation that minimizes distortion at the output of the modulator, by modifying the output swing of every integrator. The algorithm is implemented in Matlab as an evolutive searching. During each step of the searching, the algorithm evaluates the harmonical distortion of a tone when it is applied to the modulator with a certain loop-filter implementation. The output of the algorithm is an optimum linear state-space representation of the loop-filter. This particular state-space representation leads to minimum distortion at the output of the modulator when the loop-filter is implemented with some specific circuitry previously defined. As long as the search is of evolutive type, the solution represents a local minimum only. The algorithm computes a ...

2005-06-01

438

On the orbital evolution and growth of protoplanets embedded in a gaseous disc

We present an optimal control approach for the solidification process of a melt in a container. The process is described by a two phase Stefan problem with the free boundary (interface between the two phases) modelled as a graph. We control the evolution of the free boundary using the temperature on the container wall. The control goal consists in tracking a prescribed evolution of the free boundary. We achieve this goal by minimizing a appropriate cost functional. The resulting minimization problem is solved numerically by a steepest descent method with step size control, where the gradient of the cost functional is expressed in terms of the adjoint variables. Several numerical examples are presented which illustrate the performance of the method. The novelty of the approach presented consists in using a sharp interface model for the control of the free boundary. This guarantees direct access to the free boundary as optimization variable in ...

2007-05-01

439

Nuclear resonant spectroscopy at Bragg reflections from periodic multilayers: Basic effects and applications

We present a new computation of the linear tidal interaction of a protoplanetary core with a thin gaseous disc in which it is fully embedded. For the first time a discussion of the orbital evolution of cores with eccentricity (e) significantly larger than the gas-disc scale height to radius ratio (H/r) is given. We find that the direction of orbital migration reverses for e>1.1H/r. This occurs as a result of the orbital crossing of resonances in the disc that do not overlap the orbit when the eccentricity is very small. Simple expressions giving approximate fits to the eccentricity damping rate and the orbital migration rate are presented. We go on to calculate the rate of increase of the mean eccentricity for a system of protoplanetary cores due to dynamical relaxation. By equating the eccentricity damping time-scale with the dynamical relaxation time-scale we deduce that an equilibrium between eccentricity damping and excitation through scattering is attained ...

1999-01-01

440

Nonlinear pulse evolution in seeded free-electron laser amplifiers and in free-electron laser cascades

A systematic study of the Bragg nuclear resonant reflectivity from periodic multilayers in the energy and time domains is presented. Using the kinematical approach of the general reflectivity theory we describe the basic features of the time evolution of the reflected wave after a pulsed excitation of resonant multilayers by synchrotron radiation. Effects of the collective excitation have been examined such as the shift of quantum beat phases, the interplay between electronic and nuclear subsystem excitations depending on their relative position in a multilayer, the energy and time evolution of standing waves inside a resonant multilayer, and their influence on the reflectivity spectra. The exact expression for the reflectivity by a thin resonant layer placed inside a multilayer structure has been derived. The observed shift of the delayed reflectivity Bragg peak relative to the prompt peak is explained by the developed formalism. Experimental ...

2005-09-15

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441

Microstructure evolution and fracture behavior in superplastic deformation of hot-rolled AZ31 Mg alloy sheet

The advances in laser technology have made available very short and intense laser pulses which can be used to seed a high-gain single-pass free-electron laser (FEL) amplifier. With these seed pulses, a regime of the FEL interaction where the radiation evolution is simultaneously dominated by nonlinear effects (saturation) and time-dependent effects (slippage) can be explored. This regime is characterized by the propagation of a solitary wavelike pulse where the power of the optical wave grows quadratically with time, its pulse length decreases and the spectral bandwidth increases. We analyze the interplay between the field and particle dynamics of this propagation regime which was studied before and termed super-radiance. Furthermore we analyze the properties of the strong higher-order harmonic emission from this wave and its behavior when propagating in a cascade FEL. The super-radiant pulse is indeed capable of passing through the stages of a cascade FEL and to ...

2005-08-15

442

Microstructural evolution of WC-Co alloys

Fine-grained AZ31 magnesium alloy sheets were prepared through hot rolling process. The superplastic properties of hot-rolled AZ31 Mg alloy was examined by uniaxial tensile tests at a temperature range 250{proportional_to}450 C and strain rate range 0.7 x 10{sup -3}{proportional_to}1.4 x 10{sup -1} s{sup -1}. Optical and scanning electronic microscope (SEM) were used to observe the microstructure evolution and fracture behavior in superplastic deformation of AZ31 Mg alloy and the values of deformation activation energy at various temperatures were calculated. It is demonstrated that, the hot-rolled AZ31 alloy begins to exhibit superplasticity from 300 C and a maximum elongation of 362.5% is obtained at 400 C and 0.7 x 10{sup -3} s{sup -1}. In the temperature range 300{proportional_to}400 C, the dominant superplastic deformation mechanism is grain boundary sliding (GBS) controlled by grain boundary diffusion and the influence of temperature on the fracture behavior ...

2005-07-01

443

Microstructural evolution of WC-Co alloys

The microstructural development and grain-coarsening behavior of WC-Co alloys, with and without a VC additive, were investigated. The primary goal was to determine the mechanism through which VC acts as a grain-growth inhibitor. The study involved long-time sintering experiments (1 to 100 hours) on fully dense material, nascent stage sintering (90 to 1,320 seconds) starting with the green compact, and surrogate liquid phase experiments to characterize the WC powder prior to sintering. Quantitative microstructural analysis using intercept length distributions was performed for the long-term sintering. The nascent stage experiments involved the measurement of the specific surface area (S{sub v}) of each type of interface separately allowing the determination of the contribution of each developing entity to the overall microstructural evolution. The VC addition has been found to enhance the breakup of multigrained particles in the earliest stages of sintering, ...

1991-01-01

444

Mechanical properties and texture evolution of AZ31 Mg alloy during equal channel angular pressing

The microstructural development and grain-coarsening behavior of WC-Co alloys, with and without a VC additive, were investigated. The primary goal was to determine the mechanism through which VC acts as a grain-growth inhibitor. The study involved long-time sintering experiments (1 to 100 hours) on fully dense material, nascent stage sintering (90 to 1,320 seconds) starting with the green compact, and surrogate liquid phase experiments to characterize the WC powder prior to sintering. Quantitative microstructural analysis using intercept length distributions was performed for the long-term sintering. The nascent stage experiments involved the measurement of the specific surface area (S_v) of each type of interface separately allowing the determination of the contribution of each developing entity to the overall microstructural evolution. The VC addition has been found to enhance the breakup of multigrained particles in the earliest stages of sintering, producing a ...

445

Loss of flow incident - Simulation and measurements in the MPR

Microstructure and texture evolution in the AZ31 Mg alloy subject to equal channel angular pressing (ECAP) have been investigated and correlated with the mechanical properties. When AZ31 Mg alloy was ECAPed up to 8 passes following the route B{sub c}, grain refinement occurred effectively. Texture was also changed during ECAP. The original fiber texture of the extruded AZ31 Mg alloy changed to a new texture component of (01 anti 11)[5 anti 2 anti 3 anti 1], and the texture of (01 anti 11)[5 anti 2 anti 3 anti 1] orientation was rotated to (13 anti 46)[7 anti 5 anti 20] orientation after 6-pass ECAP process. The variation of the strength with the pass number was explained by the texture and grain size. The strength data of AZ31 Mg alloys followed the standard Hall-Petch relationship when the similar texture was retained during the ECAP process. Otherwise the effect of texture on strength was dominant over the strengthening due to grain refinement. (orig.)

2005-07-01

446

Local Group Dwarf Galaxies: Nature And Nurture

As part of the Probabilistic Safety Analysis of the Multi Purpose Reactor, MPR, the list of Postulated Initiating Events was analyzed and one of these PIEs corresponds to the Loss of Coolant Flow. It is well known that during the operation life of a research reactor a LOFA could eventually occur and, once this event takes place, in time detection and automatic actions, thanks to the engineering safety features of the system, will mitigate the incident evolution. The postulated event corresponds to a loss of flow due to a total loss of power supply. The goal of the present work is to provide a general description and the engineering safety features of the MPR, as well as describe the sequence of scenarios during a LOFA. Temporal evolution of main parameters is presented, also. During Stage A of the Commissioning Program measurements of the core cooling system pump coast-down were performed in order to validate previous simulation results, as ...

1999-10-26

447

Lithospheric evolution in response to triple junction migration: A program to obtain seismic images of the MTJ region

We investigate the formation and evolution of dwarf galaxies in a high resolution, hydrodynamical cosmological simulation of a Milky Way sized halo and its environment. Our simulation includes gas cooling, star formation, supernova feedback, metal enrichment and UV heating. In total, 90 satellites and more than 400 isolated dwarf galaxies are formed in the simulation, allowing a systematic study of the internal and environmental processes that determine their evolution. We find that 95% of satellite galaxies are gas-free at z=0, and identify three mechanisms for gas loss: supernova feedback, tidal stripping, and photo-evaporation due to re-ionization. Gas-rich satellite galaxies are only found with total masses above ~ 5x10^9 solar masses. In contrast, for isolated dwarf galaxies, a total mass of ~ 10^9 solar masses constitutes a sharp transition; less massive galaxies are predominantly gas-free at z=0, more massive, isolated dwarf galaxies are ...

2011-01-01

448

Is nest-drifting behaviour an insurance policy for maximising indirect fitness in primitively eusocial paper wasps?

The authors will be conducting an integrated seismic experiment to image the structure of the crust and upper mantle of northern California immediately before and after passage of the Mendocino Triple Junction. The purpose of this representation is to describe the project to other scientists interested in geological and geophysical processes in this region and to solicit input relevant to detailed siting of the funded seismic profiles. The experiment encompasses two field seasons: onshore seismic refraction/wide angle reflection data acquisition along three long profiles scheduled for late summer, 1993; and MCS deep crustal seismic reflection data acquisition accompanied by simultaneous large aperture recording using both ocean bottom and onshore seismographs, tentatively scheduled for summer, 1994. This study represents a component of a long-term, multi-disciplinary effort on the part of many investigators to exploit this well defined system as an in-situ laboratory to study ...

1993-04-01

449

Environmental Research Database

ObjectivesThe main objectives of this project are: 1. To determine whether nest-drifting behaviour allows helpers to maximise their indirect fitness in the paper wasp Polistes canadensis. Specifically, I will test a) whether nest-drifters apportion helping effort in relation to the productivity benefits of different nests (hypothesis 1a), and b) whether nest-drifters can adjust their investment in response to changes in the productivity payoffs of different nests (hypothesis 1b). 2. To determine [continued...]DescriptionDarwin's theory of natural selection predicts that organisms should act selfishly in order to pass on as many of their genes to the next generation as possible. The evolution of social behaviour is a paradox because it requires that some individuals forgo reproduction in order to help raise the offspring of others. Explaining the evolution of helping behaviour in animal societies has been a major focus for evolutionary ...

2011-01-20

450

In situ isotopic analyses of U and Pb in zircon by remotely operated SHRIMP II, and Hf by LA-ICP-MS: an example of dating and genetic evolution of zircon by 176Hf/177Hf from the Ita Quarry in the Atuba Complex, SE, Brazil

Hydrogen evolution and corrosion performance of NiZn coatings

Remotely-operated SHRIMP dating of zircon is an interesting alternative for dating of zircon crystals. Although it does not represent any technical progress of the geochronological method using the U-Pb system in zircon it is a very useful and cheap facility. The procedure was first used for mass spectrometric analyses involving two international laboratories in Sao Paulo, Brazil and Beijing, China. It was applied to samples of three gneiss-migmatitic rocks from the Ita quarry in the Atuba Complex (located between the Luis Alves and the Apiai Domain) to test previous controversial hypotheses about its evolution. The presence of important archaean and paleo proterozoic components in the complex is confirmed by analyses of zircon found in probably neo proterozoic leucosomes. Diorite intrusion also occurred during the neo proterozoic, associated with the 0.6Ga continental collisions involved in the assembly of Gondwana. The determination of Hf isotope ratios by ...

2009-10-01

451

Holography of a Composite Inflaton

The hydrogen evolution reaction (HER) was studied on bare brass (B), nickel coated brass (B/Ni), nickel-zinc alloy coated brass (B/NiZn, leached Zn), nickel (under layer)/nickel-zinc alloy coated (top layer) brass electrodes (B/Ni/NiZn, leached Zn) in 1 M NaOH solution using electrolysis, cathodic polarization and electrochemical impedance spectroscopy (EIS) techniques. Long term tests were performed in order to evaluate the electrocatalytic activity and corrosion performance of the prepared electrodes with operation time. The results showed that leached electrodes, especially B/Ni/NiZn electrode, have a smaller overpotential than the others and a good electrocatalytic activity for the HER. Its electrocatalytic activity is also stable over electrolysis time. Contrary to the HER performance, B/NiZn cannot provide an adequate corrosion protection. However, when a thin Ni layer was coated under the NiZn alloy coating (B/Ni/NiZn), a greater electrocatalytic stability ...

2007-02-01

452

Hardness and defect structures in EC316LN austenitic alloy irradiated under a simulated spallation neutron source environment using triple ion-beams

We study the time evolution of a brane construction that is holographically dual to a strongly coupled gauge theory that dynamically breaks a global symmetry through the generation of an effective composite Higgs vev. The D3/D7 system with a background magnetic field or non-trivial gauge coupling (dilaton) profile displays the symmetry breaking. We study motion of the D7 brane in the background of the D3 branes. For small field inflation in the field theory the effective Higgs vev rolls from zero to the true vacuum value. We study what phenomenological dilaton profile generates the slow rolling needed, hence learning how the strongly coupled gauge theory's coupling must run. We note that evolution of our configuration in the holographic direction, representing the phyiscs of the strong interactions, can provide additional slowing of the roll time. Inflation seems to be favoured if the coupling changes by only a small amount or very gently. We ...

2010-01-01

453

Hardness and defect structures in EC316LN austenitic alloy irradiated under a simulated spallation neutron source environment using triple ion-beams

For an assessment of the future US spallation neutron source (SNS) target performance, radiation induced hardening and microstructural evolution were investigated as a function of ion dose for EC316LN stainless steel. Irradiation was carried out using 3.5 MeV Fe{sup +}, 360 keV He{sup +}, and 180 keV H{sup +} simultaneous ion-beams at 200 deg. C to simulate the damage, He and H production in the SNS target vessel wall. At low dose (< 1 dpa), the predominant defects were black dots whose number density saturated rapidly within a few dpa. This was followed by the evolution of interstitial loops whose number density saturated below 15 dpa. Although He-bubbles were not visible, severely scalloped loops suggested that the implanted He/H atoms existed in the form of small clusters. Comparison with reported neutron irradiation data showed that hardening and ductility loss occurred mostly in the black dot regime (< 1 dpa), but that good ...

2000-04-01

454

Gravitational field and equations of motion of spinning compact binaries to 2.5 post-Newtonian order

For an assessment of the future US spallation neutron source (SNS) target performance, radiation induced hardening and microstructural evolution were investigated as a function of ion dose for EC316LN stainless steel. Irradiation was carried out using 3.5 MeV Fe"+, 360 keV He"+, and 180 keV H"+ simultaneous ion-beams at 200 deg. C to simulate the damage, He and H production in the SNS target vessel wall. At low dose (< 1 dpa), the predominant defects were black dots whose number density saturated rapidly within a few dpa. This was followed by the evolution of interstitial loops whose number density saturated below 15 dpa. Although He-bubbles were not visible, severely scalloped loops suggested that the implanted He/H atoms existed in the form of small clusters. Comparison with reported neutron irradiation data showed that hardening and ductility loss occurred mostly in the black dot regime (< 1 dpa), but that good ductility (>20% ...

2000-04-01

455

Evolution of surface roughness in silicon X-ray mirrors exposed to a low-energy ion beam

We derive spin-orbit coupling effects on the gravitational field and equations of motion of compact binaries in the 2.5 post-Newtonian approximation to general relativity, one PN order beyond where spin effects first appear. Our method is based on that of Blanchet, Faye, and Ponsot, who use a post-Newtonian metric valid for general (continuous) fluids and represent pointlike compact objects with a delta-function stress-energy tensor, regularizing divergent terms by taking the Hadamard finite part. To obtain post-Newtonian spin effects, we use a different delta-function stress-energy tensor introduced by Bailey and Israel. In a future paper we will use the 2.5PN equations of motion for spinning bodies to derive the gravitational-wave luminosity and phase evolution of binary inspirals, which will be useful in constructing matched filters for signal analysis. The gravitational field derived here may help in posing initial data for numerical ...

2001-01-01

456

Double core evolution. IV - The late stages of evolution of a 2-solar mass red giant with a 1-solar mass companion

The possibility of smoothening aspherical X-ray mirrors by irradiation of the surface with a low-energy ion beam is investigated. Nanofocusing being the primary application of these mirrors the ion beam conditions must be optimized to achieve a surface roughness of the order of 0.1-0.2 nm. To address this issue a first study was performed on silicon flat substrates etched using ion energies ranging from 400 to 1200 eV. A second study consisted of eroding the silicon surface while varying the ion grazing incidence angle between 10 deg. and 90 deg. for a fixed value of the ion energy. The surface topography of the samples was characterized at various scales using atomic force microscopy (probed area: 1-10 ?m2), interferential optical microscopy (probed area: 1 mm2) and X-ray scattering (probed area: 100 mm2). Finally, a study by AFM of the evolution of the surface finish level of a silicon mirror after ion erosion at various depth values up to 10 ?m allowed a trade ...

2010-05-01

457

Development of a methodology to assess the climate evolution and its impacts on wind energy

The paper reports on the results of hydrodynamical simulations of the late phase of the common envelope stage of a binary consisting of a 2-solar mass red giant and a 1-solar mass main-sequence companion. The numerical results demonstrate that sufficient energy is released from the orbit to eject the mass within the common envelope without requiring the main-sequence companion to spiral into the white dwarf core of the red giant star. At the end of the simulation the orbital decay time scale increases rapidly to more than 160 yr. The long decay time scale reflects the removal of mass from the common envelope and its subsequent spin-up to near corotation. The ratio of the orbital decay time scale to the mass-loss time scale from the common envelope increases to more than 700, and the mass contained within the common envelope decreases to about 0.01 solar mass or less. It is argued that further orbital decay will be small and that the final binary period will be 1.2 days. 27 refs.

458

Determination of Inter-Phase Line Tension in Langmuir Films

Maps of wind resources were used to develop a method of evaluating climatic changes and their potential impacts on wind energy resources. Global IPCC climate change scenarios were used to predict climatic conditions for the future, while past wind resource availability was simulated and validated using NCEP and NCAR reanalysis data as well as observed meteorological data from Environment Canada. The simulations were used to compare each 5-year period with a 50-year reference period. Regional scale climate change impacts were evaluated using a statistical dynamic down-scaling method. Advanced meteorological models were used to predict wind flow patterns across specific landscapes. The evolution of past wind resource availability was then simulated. Five-year wind resource simulations for a 50-year period were simulated at 25 km"2 wind speeds at 80 m above the ground. Average wind speed variations were then evaluated. The method has been used to simulate 5-year ...

2010-11-01

459

Depth dependence of defect evolution and TED during annealing

A Langmuir film is a molecularly thin film on the surface of a fluid; we study the evolution of a Langmuir film with two co-existing fluid phases driven by an inter-phase line tension and damped by the viscous drag of the underlying subfluid. Experimentally, we study an 8CB Langmuir film via digitally-imaged Brewster Angle Microscopy (BAM) in a four-roll mill setup which applies a transient strain and images the response. When a compact domain is stretched by the imposed strain, it first assumes a bola shape with two tear-drop shaped reservoirs connected by a thin tether which then slowly relaxes to a circular domain which minimizes the interfacial energy of the system. We process the digital images of the experiment to extract the domain shapes. We then use one of these shapes as an initial condition for the numerical solution of a boundary-integral model of the underlying hydrodynamics and compare the subsequent images of the experiment to the numerical ...

2007-01-01

460

Depth dependence of defect evolution and TED during annealing

A quantitative transmission electron microscopy (TEM) study on the depth profile of extended defects, formed after Si implantation, has been carried out. Two different Si{sup +} implant conditions have been considered. TEM analysis for the highest energy/dose shows that {l_brace}1 1 3{r_brace} defects evolve into dislocation loops whilst the defect depth distribution remains unchanged as a function of annealing time. For the lowest energy/dose, {l_brace}1 1 3{r_brace} defects grow and dissolve while the defect band shrinks preferentially on the surface side. At the same time, extraction of boron transient enhanced diffusion (TED) as a function of depth shows a decrease of the supersaturation towards the surface, starting at the location of the defect band. The study clearly shows that in these systems the silicon surface is the principal sink for interstitials. The results provide a critical test of the ability of physical models to simulate defect evolution and ...

2004-02-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

461

Cosmic evolution of the atomic and molecular gas content of galaxies

A quantitative transmission electron microscopy (TEM) study on the depth profile of extended defects, formed after Si implantation, has been carried out. Two different Si"+ implant conditions have been considered. TEM analysis for the highest energy/dose shows that #left brace#1 1 3#right brace# defects evolve into dislocation loops whilst the defect depth distribution remains unchanged as a function of annealing time. For the lowest energy/dose, #left brace#1 1 3#right brace# defects grow and dissolve while the defect band shrinks preferentially on the surface side. At the same time, extraction of boron transient enhanced diffusion (TED) as a function of depth shows a decrease of the supersaturation towards the surface, starting at the location of the defect band. The study clearly shows that in these systems the silicon surface is the principal sink for interstitials. The results provide a critical test of the ability of physical models to simulate defect ...

2004-02-01

462

COLLISIONAL AND LUMINOSITY EVOLUTION OF A DEBRIS DISK: THE CASE OF HD 12039

We study the evolution of the cold gas content of galaxies by splitting the interstellar medium into its atomic and molecular hydrogen components, using the galaxy formation model GALFORM in the LCDM framework. We calculate the molecular-to-atomic hydrogen mass ratio, H2/HI, in each galaxy using two different approaches; the pressure-based empirical relation of Blitz & Rosolowsky and the theoretical model of Krumholz, McKeee & Tumlinson, and apply them to consistently calculate the star formation rates of galaxies. We find that the model based on the Blitz & Rosolowsky law predicts an HI mass function, CO(1-0) luminosity function, correlations between the H2/HI ratio and stellar and cold gas mass, and infrared-CO luminosity relation in good agreement with local and high redshift observations. The HI mass function evolves weakly with redshift, with the number density of high mass galaxies decreasing with increasing redshift. In the case of the H2 mass ...

2011-01-01

463

Bi-functional oxygen electrodes using Pr-Mn-Fe-based perovskite-type oxides as catalysts

Extrasolar debris disks that are bright enough to be observed are dense enough to be collision-dominated; i.e., the small grains that produce their infrared excess have collisional lifetimes shorter than their Poynting-Robertson decay times. This paper describes a numerical code for the modeling of such disks, including accretion and gravitational stirring as well as disruptive collisions. A constraint relating the mass of a debris disk and the sizes of the largest embedded bodies to its luminosity is demonstrated. The collisional code is applied to the debris disk around HD 12039, which has been intensively observed by the Spitzer Space Telescope. The evolution in time of the disk's luminosity is computed for a range of initial disk masses and planetesimal sizes. The luminosity at a given age depends on both the initial disk mass and the initial size of the planetesimals. Luminosity decays more rapidly for massive disks due to the combination of collisional ...

2010-10-20

464

Baryon history and cosmic star formation in non-Gaussian cosmological models: numerical simulations

To develop oxygen electrodes for rechargeable metal-air batteries, the electrochemical behaviour of gas-diffusion-type carbon electrodes loaded with Pr-Mn-Fe-based perovskite-type oxides was examined for the reduction and evolution of oxygen in 8 M KOH at 60 C. Among the oxides tested, Pr{sub 0.2}Ca{sub 0.8}Mn{sub 0.1}Fe{sub 0.9}O{sub 3} gave the highest electrode performances, e.g., current densities of 275 mA/cm{sup 2} (for oxygen reduction) and 225 mA/cm{sup 2} (for oxygen evolution) at -300 and +650 mV vs. Hg/HgO, respectively. The electrode performances were found to depend on both the catalytic activity of the oxides for H{sub 2}O{sub 2} decomposition reaction and the amounts of oxygen desorbed from the oxides. Furthermore, it was confirmed that the small zinc-air battery including the gas-diffusion-type electrode loaded with Pr{sub 0.2}Ca{sub 0.8}Mn{sub 0.1}Fe{sub 0.9}O{sub 3} showed good discharge and charge characteristics. (orig.)

1999-07-01

465

British Library Electronic Table of Contents (United Kingdom)

Abstract We present the first numerical,-N-body, hydrodynamical, chemical simulations of cosmic structure formation in the framework of non-Gaussian models. We study the impact of primordial non-Gaussianities on early chemistry (e-, H, H+, H-, He, He+, He++, H2, H+2, D, D+, HD, HeH+), molecular and atomic gas cooling, star formation, metal (C, O, Si, Fe, Mg, S) enrichment, Population-III (popIII) and Population-II-I (popII) transition and on the evolution of -visible- objects. We find that non-Gaussianities can have some consequences on baryonic structure formation at very early epochs, but the subsequent evolution at later times washes out any difference among the various models. When assuming reasonable values for primordial non-Gaussian perturbations, it turns out that they are responsi...

2011-01-01

466

Atomistic analysis of defect evolution and transient enhanced diffusion in silicon

Analysis on depositional system and discussion on ore-formation conditions of channel sandstone type uranium deposit. Taking Dongsheng area, Ordos meso-cenozoic basin as an example

Kinetic Monte Carlo simulations are used to analyze the ripening and dissolution of small Si interstitial clusters and #left brace#113#right brace# defects, and its influence on transient enhanced diffusion of dopants in silicon. The evolution of Si interstitial defects is studied in terms of the probabilities of emitted Si interstitials being recaptured by other defects or in turn being annihilated at the surface. These two probabilities are related to the average distance among defects and their distance to the surface, respectively. During the initial stages of the defect ripening, when the defect concentration is high enough and the distance among them is small, Si interstitials are mostly exchanged among defects with a minimal loss of them to the surface. Only when defects grow to large sizes and their concentration decreases, the loss of Si interstitials through diffusion to the surface prevails, causing their dissolution. The presence of large and stable ...

2003-07-15

467

Action Potentials in a Giant Algal Cell: A Comparative Approach to Mechanisms and Evolution of Excitability

Applying the theory of depositional system, the depositional facies and depositional systems of the Zhiluo Formation in Dongsheng area are systematically analysed, and the authors proposed that sediments of the Zhiluo Formation are of fluvial facies, and streams of the Zhiluo time experienced three evolution stages, namely: the early braided stream, the middle low sinuosity meandering stream and the late high sinuosity meandering stream. Based on features of paleoclimatic evolution, the Zhiluo Formation is divided into two lithological members. The lower lithological member consists of sediments of braided and low sinuosity meandering streams under humid-ward paleoclimatic conditions forming grey sedimentary formation. The upper member is composed of sediments of meandering streams under arid-hot paleoclimatic conditions representing complex-colored (mainly red) sedimentary formation. It is suggested that uranium mineralization in the study ...

2003-03-01

468

Accurate evolutions of unequal-mass neutron-star binaries: properties of the torus and short GRB engines

The giant alga Chara corallina generates action potentials (APs) in response to mechanical stimulation, injury, or direct electrical stimulation. Students examine the waveform characteristics of these APs using standard intracellular recording techniques. Intracellular recording is easier than with neurons because of the large size of the Chara cell. Students observe very negative resting potentials (up to -250 mV), large AP amplitudes with depolarizing peaks approaching 0 mV, AP durations of seconds, and refractory periods up to several minutes. Students calculate Nernst potentials for the ions distributed across the Chara cell membrane to hypothesize the ions responsible for the resting potential and for the depolarizing phase of the AP. These calculations suggest that K+ is responsible for the resting potential and that Ca2+ influx and Ca2+-activated Cl- efflux are responsible for depolarizing phases of the AP, which they are. Comparison of the Chara AP characteristics with animal ...

2008-06-11

469

A simple model for the short-time evolution of near-surface current and temperature profiles

We present new results from accurate and fully general-relativistic simulations of the coalescence of unmagnetized binary neutron stars with various mass ratios. The evolution of the stars is followed through the inspiral phase, the merger and prompt collapse to a black hole, up until the appearance of a thick accretion disk, which is studied as it enters and remains in a regime of quasi-steady accretion. Although a simple ideal-fluid equation of state with \\Gamma=2 is used, this work presents a systematic study within a fully general relativistic framework of the properties of the resulting black-hole--torus system produced by the merger of unequal-mass binaries. More specifically, we show that: (1) The mass of the torus increases considerably with the mass asymmetry and equal-mass binaries do not produce significant tori if they have a total baryonic mass M_tot >~ 3.7 M_sun; (2) Tori with masses M_tor ~ 0.2 M_sun are measured for binaries with M_tot ~ 3.4 ...

2010-01-01

470

A Direct Precision Measurement of the Intergalactic Lyman-alpha Opacity at 2

A simple analytical/numerical model has been developed for computing the evolution, over periods of up to a few hours, of the current and temperature profile in the upper layer of the ocean. The model is based upon conservation laws for heat and momentum, and employs an eddy diffusion parameterisation which is dependent on both the wind speed and the wind stress applied at the sea surface. Other parameters such as the bulk-skin surface temperature difference and CO$_2$ flux are determined by application of the Molecular Oceanic Boundary Layer Model (MOBLAM) of Schluessel and Soloviev. A similar model, for the current profile only, predicts a temporary increase in wave breaking intensity and decrease in wave height under conditions where the wind speed increases suddenly, such as, for example, during gusts and squalls. The model results are compared with measurements from the lagrangian Skin Depth Experimental Profiler (SkinDeEP) surface profiling instrument made ...

2005-01-01

471

radiation hardening and microstructure evolution in austenitic chromium-nickel steel under various type irradiation

We directly measure the evolution of the intergalactic Lyman-alpha effective optical depth, tau_eff, over the redshift range 2 is <1% at z=2, 4% at z=3, and 12% at z=4. Previous measurements of tau_eff at 3evolution (tau_eff=0.0018(1+z)^3.92, when metals are left in), particularly near z=3.2. The observed downward departure is statistically consistent with a ...

2007-01-01

472

[The study of the mixing layer by the point image method].

A study was made into microstructure and hardening in austenitic stainless steel 0Kh18N10T irradiated with neon ions (230 MeV) and neutrons (E_n > 0.1 MeV). The experiments were accomplished using an external beam of U-400 cyclotron (Dubna) and EWA reactor (Poland). The dependences of tensile properties, hardening index, microstructure, dislocation density on damaging dose were determined. An attempt is made to reveal the correlation between an yield strength increment and defect cluster accumulation. The interpretation of variations of mechanical properties and microstructure under irradiation is given.

473

Topoisomerases of kinetoplastid parasites: why so fascinating?

The properties of the mixing layer in dynamic systems were studied by the example of a mathematical model of the cubic image type. Its role in the generation of information and the evolution of its significance was shown. At the moment of generation, information is of zero significance, and this significance then increases. A criterion of efficiency was proposed, and the optimum moment of making a decision in creative work was determined. It was shown that the increase in the variability of the parameters of a living system upon entry into the mixing layer and its decrease upon exit can serve as objective indicators of the transition of the system from one dynamic regime (attractor) to another. PMID:12723364

474

British Library Electronic Table of Contents (United Kingdom)

Summary DNA topoisomerases are the key enzymes involved in carrying out high precision DNA transactions inside the cells. However, they are detrimental to the cell when a wide variety of topoisomerase-targeted drugs generate cytotoxic lesions by trapping the enzymes in covalent complexes on the DNA. The discovery of unusual heterodimeric topoisomerase I in kinetoplastid family added a new twist in topoisomerase research related to evolution, functional conservation and their preferential sensitivity to Camptothecin. On the other hand, structural and mechanistic studies on kinetoplastid topoisomerase II delineate some distinguishing features that differentiate the parasitic enzyme from its prokaryotic and eukaryotic counterparts. This review summarizes the recent advances in research in kin...

2006-01-01

475

The kinematics of early type galaxies

Study of the influence of surface carbon on the tribological properties of ion-treated steels

An account is given of the existence of kinematic subsystems in elliptical galaxies, in conjunction with discussions of the application of statistical tests to determine whether ellipticals are triaxial, and of the modified Faber-Jackson relation for elliptical galaxies. Recent data obtained by Kormendy (1988) and Dressler and Richstone (1988) on the kinematics of the M31, M32, and NGC 4594 central regions indicate both very steep rotation curves and peaked velocity dispersion profiles. If elliptical galaxies are triaxial, and if it is common for them to have accreted other galaxies during their evolution, then both a source of fuel for an active nucleus and a mechanism for getting that fuel from outside the galaxy into its center is available. 61 refs.

1988-04-12

476

Singularities and Closed String Tachyons

Samples of 100Cr6 steel were treated by different ion beams in order to study the evolution of their tribological properties. A strong correlation was found between the amount of surface carbon, whatever its origin (contamination, direct C implantation or ion-beam mixing of a deposited carbon layer), and the reduction of the friction coefficient as well as the improvement of the wear resistance. These results are discussed in the framework of a recent statistical model founded on the asperity concept and describing the tribological behaviour of bilayer systems.

1999-01-02

477

Self-interstitial supersaturation during Ostwald ripening of end-of-range defects in ion-implanted silicon

A basic problem in gravitational physics is the resolution of spacetime singularities where general relativity breaks down. The simplest such singularities are conical singularities arising from orbifold identifications of flat space, and the most challenging are spacelike singularities inside black holes (and in cosmology). Topology changing processes also require evolution through classically singular spacetimes. I briefly review how a phase of closed string tachyon condensate replaces, and helps to resolve, basic singularities of each of these types. Finally I discuss some interesting features of singularities arising in the small volume limit of compact negatively curved spaces and the emerging zoology of spacelike singularities.

2006-03-17

478

Scattering and Recombination of Two Triplet Excitons in polymer light-emitting diodes

Modified Ostwald ripening theory is used to calculate the time evolution of the size distribution function of extended end-of-range defects in ion implanted silicon. This allows the authors to compare the time dependent self-interstitial supersaturation during post-implantation annealing in the presence of Frank-type stacking faults with that in the presence of {l_brace}311{r_brace}-defects. It is shown that the latter affect self-interstitial concentrations up to the point where they dissolve whereas the former are irrelevant from the point of view of transient enhanced diffusion.

1996-12-01

479

Pansystems traffics, logistics and knowledge rediscovery

The scattering and recombination processes between two triplet excitons in conjugated polymers are investigated by using a nonadiabatic evolution method, based on an extended Su-Schrieffer-Heeger model including interchain interactions. Due to the interchain coupling, the electron and/or hole in the two triplet excitons can exchange. The results show that the recombination induces the formation of singlet excitons, excited polarons and biexcitons. Moreover, we also find the yields of these products, which can contribute to the emission, increase with the interchain coupling strength, in good agreement with results from experiments.

2010-01-01

480

British Library Electronic Table of Contents (United Kingdom)

Purpose - The purpose of this paper is to develop pansystems-styled traffics, logistics and knowledge rediscovery. The core logoi are the generalized resources//F* and their circulation//C*. The research presents a new outlook to mathematics, physics, traffic, communication, logistics, KD, internet, computer, translation, simulation, information, life-systems, logic or reasoning, memory or storage, process, transaction, finance, education, inherent, topology, evolution, etc. and then certain mechanism among them and related mutuality can be unveiled. Design/methodology/approach - A flexible combination of philosophy, mathematics and technology is embodied. The paper is an application of pansystems methodology to approach the following topics: pansystems resource, circulation: traffics, log...

2009-01-01

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481

Origin of binary stars

Nonlinear evolution of coarse-grained quantum systems with generalized purity constraints

Results of analytical study of early stages of a single star evolution are used investigation of the rotational fragmentation of the collapsing gas-dust cloud which leads to formation of two types of binaries. Wide ..cap alpha..-systems (Psub(orb) > or approximately 100 yrs) with usually unequal masses of components are formed before the formation of gas-dust core in hydrostatical equilibrium. Close ..beta..-systems (Psub(orb) < or approximation 100 yrs) with usually nearly equal masses of components are formed in the course of the collapse of gas-dust core.

1983-03-01

482

Mutual recombination and clusterization effect of the vacancy and interstitial barriers on radiation hardening materials

Constrained quantum dynamics is used to propose a nonlinear dynamical equation for pure states of a generalized coarse-grained system. The relevant constraint is given either by the generalized purity or by the generalized invariant fluctuation, and the coarse-grained pure states correspond to the generalized coherent i.e. generalized nonentangled states. Open system model of the coarse-graining is discussed. It is shown that in this model and in the weak coupling limit the constrained dynamical equations coincide with an equation for pointer states, based on Hilbert-Schmidt distance, that was previously suggested in the context of the decoherence theory.

2010-01-01

483

British Library Electronic Table of Contents (United Kingdom)

There is proposed the nonlinear model of dose dependence saturation of the yield strength on the base of the vacancy and interstitial barrier interaction in this work. Processes of mutual recombination of vacancy and interstitial barriers and formation of vacancy and interstitial clusters are taken into consideration. In the framework of the model, the analytical equations corresponding to the evolution of the barrier densities and yield strength are obtained. It is shown that the yield strength of irradiated materials decreases with the increasing intensity of barrier recombination processes, the dependence being nonlinear. Also it is shown that the model is valid both for low doses and large doses on the stage of radiation hardening.

2009-01-01

484

Monitoring the atmospheric stability by using radon concentration measurements. A study in a Central Italy site

Modeling of dislocation loop growth and transient enhanced diffusion in silicon for amorphizing implants

Meteorological and radon concentration data referring to a measurement campaign carried out in Urbino, Central Italy, are reported and discussed. This study presents a method allowing monitoring of the vertical atmospheric stability using continuous measurements of radon gas near ground. In particular radon evidences the presence of temperature inversion such as the formation of the nocturnal stable layer and gives information on the vertical turbulence and the motion of air masses. This technique is very useful in describing the temporal evolution of the pollutants in the atmosphere. (author)

2006-12-01

485

Modeling of dislocation loop growth and transient enhanced diffusion in silicon for amorphizing implants

It has been observed that dislocation loops form and grow during annealing of silicon wafers implanted at doses above the amorphization threshold. Dislocation loops can act to store interstitials for prolonged periods of anneals, sustaining an interstitial super-saturation and thus causing substantial transient enhanced diffusion (TED). The authors have developed a comprehensive model which, in combination with a model and parameters for {l_brace}311{r_brace} defects from previous work, accounts for the formation and evolution of dislocation loops during ion implant annealing, as well as giving the correct TED behavior.

1997-11-01

486

Leak sealing on ancillary cooling circuits of CANDU reactors

It has been observed that dislocation loops form and grow during annealing of silicon wafers implanted at doses above the amorphization threshold. Dislocation loops can act to store interstitials for prolonged periods of anneals, sustaining an interstitial super-saturation and thus causing substantial transient enhanced diffusion (TED). The authors have developed a comprehensive model which, in combination with a model and parameters for #left brace#311#right brace# defects from previous work, accounts for the formation and evolution of dislocation loops during ion implant annealing, as well as giving the correct TED behavior.

1996-12-02

487

Kaon properties in (proto-)neutron star matter

This paper discusses the remote plugging of leaks in inaccessible pipework, with main reference to small leaks which frequently appear in ancillary cooling water circuits of nuclear reactors. Initially developed to cure problems of the pre-stressed concrete pressure vessels of UK reactors, the ZORIC sealant has been used to repair leaking biological shield pipework on six CANDU reactors. ZORIC is based on a water-soluble epoxy resin and an aqueous suspension of a refined mineral clay. This paper describes the evolution of the sealant, the qualification and testing program, and their application to CANDU reactor systems. 2 refs., 6 figs.

1992-11-22

488

British Library Electronic Table of Contents (United Kingdom)

Abstract. The modification of kaon and antikaon properties in the interior of (proto-)neutron stars is investigated using a chiral SU(3) model. The parameters of the model are fitted to nuclear-matter saturation properties, baryon octet vacuum masses, hyperon optical potentials and low-energy kaon-nucleon scattering lengths. We study the kaon/antikaon medium modification and explore the possibility of antikaon condensation in (proto-)neutron star matter at zero as well as finite temperature/entropy and neutrino content. The effect of hyperons on kaon and antikaon optical potentials is also investigated at different stages of the neutron star evolution.

2010-01-01

489

Investigation of three red giants observed in the CoRoT seismo field

Interpreting Mammalian Evolution using Fugu Genome Comparisons

Three red giants (HD 49566 (G5III), HD 169370 (K0III) and HD 169751 (K2III)) have been observed in the CoRoT seismo field and additional ground-based spectra have been acquired. We present preliminary results of a detailed study of these stars using the observational constraints from the spectra and CoRoT data, and models from the YREC stellar evolution code.

2011-01-01

490

Indirect stabilization of weakly coupled systems with hybrid boundary conditions

Comparative sequence analysis of the human and the pufferfish Fugu rubripes (fugu) genomes has revealed several novel functional coding and noncoding regions in the human genome. In particular, the fugu genome has been extremely valuable for identifying transcriptional regulatory elements in human loci harboring unusually high levels of evolutionary conservation to rodent genomes. In such regions, the large evolutionary distance between human and fishes provides an additional filter through which functional noncoding elements can be detected with high efficiency.

2004-04-02

491

High resolution transmission electron microscopy of partial states of oxygen order in YBa_2Cu_3O_z

We investigate stability properties of indirectly damped systems of evolution equations in Hilbert spaces, under new compatibility assumptions. We prove polynomial decay for the energy of solutions and optimize our results by interpolation techniques, obtaining a full range of power-like decay rates. In particular, we give explicit estimates with respect to the initial data. We discuss several applications to hyperbolic systems with {\\em hybrid} boundary conditions, including the coupling of two wave equations subject to Dirichlet and Robin type boundary conditions, respectively.

2011-01-01

492

Gravitational Waves from Collapsing Domain Walls

This paper reports on high resolution electron microscopy used to investigate the effect of electron irradiation induced oxygen loss on the states of partial order in YBa_2Cu_3O_z. Contrast effects visible in the [001] zone image as a result of the degree of the out-of-plane correlation of these ordered states are investigated. Using statistical simulations to aid in the analysis of the HREM images, an interpretation based on a kinetically limited evolution of the variation of long range [001] ordering is proposed.

1990-04-16

493

Global Value Chains and Open Networks: The Case of Italian Industrial Districts

We study the production of gravitational waves from cosmic domain walls created during phase transition in the early universe. We investigate the process of formation and evolution of domain walls by running three dimensional lattice simulations. If we introduce an approximate discrete symmetry, walls become metastable and finally disappear. We calculate the spectrum of gravitational waves produced by collapsing metastable domain walls. Extrapolating the numerical results, we find the signal of gravitational waves produced by domain walls whose energy scale is around 10^10-10^12GeV will be observable in the next generation gravitational wave interferometers.

2010-01-01

494

British Library Electronic Table of Contents (United Kingdom)

Italian district small and medium enterprises (SMEs) developed aggressive strategies to extend their sales networks and supply chains abroad. Literature on districts offered alternative explanations about the impacts of internationalization on local manufacturing systems. The authors consider the evolution of Italian districts in the framework of global value chain approach, focusing on the role of leading firms. Based on a survey of 650 Italian SMEs and financial indicators, the paper describes the rise of a new district firm model, the open network, which becomes a key node of global value chains. The paper also analyses the relationships among internationalization, innovation strategies and performance of SMEs.

2010-01-01

495

Geological setting of the Paleoproterozoic Rosebel gold district, Guiana Shield, Suriname

British Library Electronic Table of Contents (United Kingdom)

The Rosebel gold district is hosted in a Paleoproterozoic greenstone belt of the Guiana Shield and has many characteristics that enable classification of the ores as an orogenic gold deposit. Host rocks have undergone several phases of deformation. However, gold deposition occurred late in the structural history of the belt, and is considered part of a late regional metallogenic event with respect to the geotectonic evolution of the Guiana Shield. Economic gold mineralization is hosted in felsic to mafic volcanic rocks and two sedimentary successions that are differentiated into turbiditic and arenitic depositional packages. The detailed lithostratigraphic characterization and the geochemistry enable the correlation of the local rock types with the Paramaka, the Armina, and the Rosebel for...

2011-01-01

496

Cores of early-type galaxies - the nature of dwarf spheroidal galaxies

Closed string tachyons and their implications for non-supersymmetric strings

The characteristics and evolution of dwarf spheroidal galaxies (DSGs) are modeled on the basis of high-resolution CCD photometry obtained with the Canada-France-Hawaii telescope and reported by Kormendy (1986). The data and the results of core-parameter correlation studies are presented in extensive graphs and discussed. It is inferred that at least some DSGs are formed by the stripping of gas from dwarf spiral and irregular galaxies, although internal gas processes may also be important. The hypothesis that DSGs represent the faint end of the elliptical-galaxy sequence appears to be ruled out. 50 references.

497

COBE confounds the cosmologists

Closed string tachyons have long been somewhat mysterious. We note that there is often a regime in the classical moduli space in which one can systematically compute the effective action for such fields. In this regime, the tachyon is light, and cannot be integrated out. Instead, one must consider the combined dynamics of gravitons, moduli, tachyons and other light fields. We compute the action and find that the quartic term for the tachyon is positive in the field definition where the tachyon has no derivative coupling to the radion. We study the evolution of isotropic, homogeneous configurations and find that typically the system is driven to regions where the calculation is no longer under control. (author)

2004-07-01

498

Algorithmic tangent stiffness in elastoplasticity and elastoviscoplasticity: A geometric insight

The validity of the Big Bang theory is evaluated. The basis of the Big Band theory and the supercluster observations of Tully, which conflict with the Big Band theory, are discussed. Various explanations for the existence of supercluster observations are proposed. The cosmic background explorer (COBE) is being utilized to detect energetic processes. The COBE contains a far IR absolute spectrometer, a differential microwave radiometer, and a diffuse IR background experiment. The hypothesis of the evolution of the universe of Hannes Alfven, which emphasizes the importance of electricity and magnetism, is presented and research illustrating the importance of electric currents and magnetic fields in space is examined.

1990-03-01

499

British Library Electronic Table of Contents (United Kingdom)

The algorithmic, or consistent, tangent stiffness was introduced to improve the asymptotic convergence rate of the iterative correction algorithm for the evolutive analysis of elastoplastic structures. The original approach is based on a formulation of the elastoplastic law in terms of a plastic multiplier with an analysis which, in general, requires an operator inversion. A geometric description of the method, based on hypersurface theory, is proposed here to provide a clear picture of the algorithmic properties. An estimate of the tangent stiffness associated with finite step elastoplastic and elastoviscoplastic constitutive models is given. It is based on the properties of the projection operator on the elastic domain and avoids operator inversions retaining the beneficial properties of...

2010-01-01

500

Adiabatic Rormation of a Matched-beam Distribution for an Alternating-gradient Quadrupole Lattice