bluuebunny/crossref_metadata_2025 huggingface dataset:
Laser plasma generation and plasma interaction with ablative
target
Authors: BEILIS ISAK I.
Published: February 2007

The model of plasma production by laser radiation onto a solid target
was developed taking into account plasma heating by the emitted electrons
and target heating by ion bombardment, as well as by the laser radiation.
The near target plasma structure was analyzed. The space charge sheath was
studied solving the Poisson equation and taking into account the volume
charge of accelerated electrons and ions. The kinetics of atoms evaporated
from the target and the back-flow of atoms and ions from the plasma
towards the surface was analyzed. A system of equations, including
equations for solid heat conduction, plasma generation and the plasma
expansion was formulated. The calculation for Cu target, laser spot radius
100 μm, pulse duration 1 ms, 103, 10, 1ns and laser power
density qL = 10−3–1
GW/cm2 was conducted. The ratio of net evaporation rate to
the total evaporated mass flux was determined. It was shown that the
plasma mainly generated in the electron emission beam relaxation region
and there the plasma flow is subsonic. The electric field at the target
surface is relatively large and therefore the ion current to the surface
in the space region is large and comparable with the electron emission
current. A large contribution of the plasma energy flux in the target heat
regime was obtained, showing that the laser generated plasma significantly
converts the absorbed laser energy to kinetic and potential energy of the
plasma particles, which transport part of the energy through the
electrostatic sheath to the solid surface.
Production of multi-MeV per nucleon ions in the controlled amount of
matter mode (CAM) by using causally isolated targets
Authors: STRANGIO C. , CARUSO A. , NEELY D. , ANDREOLI P.L. , ANZALONE R. , CLARKE R. , CRISTOFARI G. , DEL PRETE E. , DI GIORGIO G. , MURPHY C. , RICCI C. , STEVENS R. , TOLLEY M.
Published: February 2007

In several experiments, faster ions were produced from the backside of
solid targets irradiated by powerful laser pulses. The ion acceleration
was considered due to the negative electrostatic sheath formed on the
backside of the target (TNSA), or to the expansion wave starting at the
backside surface, or to the expansion wave and to its embedded
electrostatic rarefaction shock. In this experiment, ions have been
generated by transferring energy to a controlled amount of mass before the
target become transparent by gas dynamic expansion (controlled amount of
mass mode (CAM)). The targets used were thin transparent disks
causally isolated from the holder to trim down, during the
interaction process, unwanted effects due to the surrounding parts. Two
kinds of target corresponding to a different set of parameters were
designed (LARGE and SMALL). Both targets were conceived to survive, in the
actual contrast conditions, to the low power pulse forerunning the giant
laser pulse, bigger margin but lower performances being assigned to LARGE.
For comparison standard square foils under the same focusing conditions,
were also studied (LARGE-LIKE and SMALL-LIKE irradiation).
Optimization of the non-normal incidence, transient pumped plasma
X-ray laser for laser spectroscopy and plasma diagnostics at the facility
for antiproton and ion research (FAIR)
Authors: KUEHL TH. , URSESCU D. , BAGNOUD V. , JAVORKOVA D. , ROSMEJ O. , CASSOU K. , KAZAMIAS S. , KLISNICK A. , ROS D. , NICKLES P. , ZIELBAUER B. , DUNN J. , NEUMAYER P. , PERT G. ,   The PHELIX TEAM
Published: February 2007

Intense and stable laser operation with Ni-like Zr and Ag was
demonstrated at pump energies between 2 J and 5 J energy from the PHELIX
pre-amplifier section. A novel single mirror focusing scheme for the TCE
x-ray laser (XRL) has been successfully implemented by the
LIXAM/MBI/GSI collaboration under different pump geometries. This
shows potential for an extension to shorter XRL wavelength. Generation of
high quality XRL beams for XRL spectroscopy of highly charged ions is an
important issue within the scientific program of PHELIX. Long range
perspective is the study of nuclear properties of radioactive isotopes
within the FAIR project.
Investigation of the impact of SBS-parameters and loss modulation on
the mode locking of an SBS-laser oscillator
Authors: KAPPE PHILIP , STRÄßER ALEXANDER , OSTERMEYER MARTIN
Published: February 2007

A Nd:YAG laser oscillator Q-switched and mode locked via a nonlinear
mirror based on stimulated Brillouin scattering (SBS) and aided by an
acousto optical modulator (AOM) has been realised. A rate equation model
and a round trip model are used to describe the longitudinal mode
dynamics. Parameter variations of the nonlinear SBS mirror and the loss
modulating AOM in the resonator are investigated with regard to their
effect on the pulse duration and spectra of the pulses.
The importance of land-based prey for sympatrically breeding giant petrels at sub-Antarctic Marion Island
Authors: de Bruyn P.J. Nico , Cooper John , Bester Marthán N. , Tosh Cheryl A.
Published: February 2007

Northern (Macronectes halli) and southern (M. giganteus) giant petrels breed at different times at sub-Antarctic Marion Island. Long-term census and breeding success data are used to test for competitive overlap between the two species by correlating population trends with those of land-based prey/carrion species. No parameter was singularly important in population regulation of either giant petrel species and the assumed dependence of breeding northern giant petrels on southern elephant seal Mirounga leonina carrion is not entirely supported.
Effects of giant icebergs on two emperor penguin colonies in the Ross Sea, Antarctica
Authors: Kooyman Gerald L. , Ainley David G. , Ballard Grant , Ponganis Paul J.
Published: February 2007

The arrival in January 2001 in the south-west Ross Sea of two giant icebergs, C16 and B15A, subsequently had dramatic affects on two emperor penguin colonies. B15A collided with the north-west tongue of the Ross Ice Shelf at Cape Crozier, Ross Island, in the following months and destroyed the penguins' nesting habitat. The colony totally failed in 2001, and years after, with the icebergs still in place, exhibited reduced production that ranged from 0 to 40% of the 1201 chicks produced in 2000. At Beaufort Island, 70 km NW of Crozier, chick production declined to 6% of the 2000 count by 2004. Collisions with the Ross Ice Shelf at Cape Crozier caused incubating adults to be crushed, trapped in ravines, or to abandon the colony and, since 2001, to occupy poorer habitat. The icebergs separated Beaufort Island from the Ross Sea Polynya, formerly an easy route to feeding and wintering areas. This episode has provided a glimpse of events which have probably occurred infrequently since the West Antarctic Ice Sheet began to retreat 12 000 years ago. The results allow assessment of recovery rates for one colony decimated by both adult and chick mortality, and the other colony by adult abandonment and chick mortality.
Conserving pattern and process in the Southern Ocean: designing a Marine Protected Area for the Prince Edward Islands
Authors: Lombard A.T. , Reyers B. , Schonegevel L.Y. , Cooper J. , Smith-Adao L.B. , Nel D.C. , Froneman P.W. , Ansorge I.J. , Bester M.N. , Tosh C.A. , Strauss T. , Akkers T. , Gon O. , Leslie R.W. , Chown S.L.
Published: February 2007

South Africa is currently proclaiming a Marine Protected Area (MPA) in the Exclusive Economic Zone (EEZ) of its sub-Antarctic Prince Edward Islands. The objectives of the MPA are to: 1) contribute to a national and global representative system of MPAs, 2) serve as a scientific reference point to inform future management, 3) contribute to the recovery of the Patagonian toothfish (Dissostichus eleginoides), and 4) reduce the bird bycatch of the toothfish fishery, particularly of albatrosses and petrels. This study employs systematic conservation planning methods to delineate a MPA within the EEZ that will conserve biodiversity patterns and processes within sensible management boundaries, while minimizing conflict with the legal toothfish fishery. After collating all available distributional data on species, benthic habitats and ecosystem processes, we used C-Plan software to delineate a MPA with three management zones: four IUCN Category Ia reserves (13% of EEZ); two Conservation Zones (21% of EEZ); and three Category IV reserves (remainder of EEZ). Compromises between conservation target achievement and the area required by the MPA are apparent in the final reserve design. The proposed MPA boundaries are expected to change over time as new data become available and as impacts of climate change become more evident.
Chick-rearing Crozet shags (Phalacrocorax melanogenis) display sex-specific foraging behaviour
Authors: Cook Timothée R. , Cherel Yves , Bost Charles-André , Tremblay Yann
Published: February 2007

We compared, for the first time the foraging ecology of both sexes of the blue-eyed Crozet shag (Phalacrocorax melanogenis), using ventrally attached time depth recorders to investigate differences in time-budget and diving behaviour between the sexes during the chick-rearing. Males were the only ones to dive over 55 m. Females dived mostly between 15 and 35 m, a zone poorly used by males. Females foraged mostly in the morning and males in the afternoon. Females also spent one hour longer diving per day compared to males. There were differences in diving strategies and diet, indicating that both sexes targeted essentially the same prey, but of different sizes, males specializing in bigger fish. Although the relationship between sexual dimorphism and diving depth was positive (larger animals diving deeper), evidence suggests that body size (in terms of oxygen storage capacity) is not sufficient to explain so many differences in foraging ecology. Instead, we propose prey size (possibly driven by a limitation of prey handling ability in relation to beak size) could be an essential factor in shaping the male/female behavioural segregation in the Crozet shag; future studies should concentrate on this particular aspect.
Thermal history of the Vestfold Hills (East Antarctica) between Lambert rifting and Gondwana break-up, evidence from apatite fission track data
Authors: Lisker Frank , Wilson Christopher J.L. , Gibson Helen J.
Published: February 2007

Analysis of five basement samples from the Vestfold Hills (East Antarctica) reveals pooled apatite fission track (FT) ages ranging from 188 to 264 Ma and mean lengths of 13.7 to 14.9 μm. Quantitative thermal histories derived from these data give consistent results indicating onset of cooling/denudation began sometime prior to 240 Ma, with final cooling below 105°–125°C occurring between 240 and 220 Ma (Triassic). A Cretaceous denudation phase can be inferred from the sedimentary record of the Prydz Bay offshore the Vestfold Hills. The two denudational episodes are likely associated with Palaeozoic large-scale rifting processes that led to the formation of the adjacent Lambert Graben, and to the Cretaceous Gondwana break-up between Antarctica and India. Subsequent evolution of the East Antarctic passive continental margin likely occurred throughout the Cenozoic based on the depositional record in Prydz Bay and constraints (though tentative) from FT data.
George VI Ice Shelf: past history, present behaviour and potential mechanisms for future collapse
Authors: Smith James A. , Bentley Michael J. , Hodgson Dominic A. , Cook Alison J.
Published: February 2007

George VI Ice Shelf is the largest ice shelf on the west coast of the Antarctic Peninsula, covering a total area of 25 000 km2. The northern ice front of George VI Ice Shelf presently marks the southernmost occurrence of recent ice-shelf retreat on the Antarctic Peninsula and according to some predictions the ice shelf is close to its thermal limit of stability. If these predictions are accurate and we are witnessing the first stages of retreat then it is critical that we take the opportunity to examine the ice shelf in its pre-collapse phase. This paper provides a review of the geological evolution, glaciology and interactions between the ocean and the atmosphere. We also discuss the present behaviour of the ice shelf, in the context of recent retreat of its northern and southern ice fronts, and outline several possible mechanisms for future ice shelf collapse. What emerges from this review is that the stability of George VI Ice Shelf is sensitive not only to the recent rapid regional atmospheric warming on the Antarctic Peninsula which has led to the gradual retreat of the northern and southern ice shelf fronts, but also to changes in ocean circulation, particularly intrusions of warm Upper Circumpolar Deep Water onto the continental shelf. It is likely that any future change in the stability of George VI Ice Shelf will involve a combined atmospheric and oceanic forcing.
Changes in soil organic carbon induced by tillage and water erosion on a steep cultivated hillslope in the Chinese Loess Plateau from 1898–1954 and 1954–1998
Authors: Li Y. , Zhang Q. W. , Reicosky D. C. , Lindstrom M. J. , Bai L. Y. , Li L.
Published: February 2007

The fate of soil organic carbon (SOC) transported and redistributed by erosion over steep agricultural landscapes is uncertain. The effect of topography, slope, and slope position on SOC redistribution must be considered. Our objectives were to (1) determine the spatial patterns of both tillage and water erosion‐induced SOC redistribution, (2) evaluate the compensating effects of tillage‐induced soil redistribution on SOC loss due to water erosion, and (3) quantify changes of SOC storage between 1898–1954 and 1954–1998 periods. To meet these objectives, we conducted field sampling and investigated a cultivated hillslope in the Fangzhuang gully of Xigoumao catchment in Chinese Loess Plateau. Soil organic carbon redistribution was calculated by multiplying SOC concentration by total soil redistribution (TSR) including both tillage and water‐induced soil redistribution derived from137Cs and210Pbexinventories and from the tillage erosion prediction (TEP) model. Our results showed that the hillslope soil had an 89% decrease of137Cs inventories for the last 45 years and a 55% decrease of210Pbexinventories for the last 100 years. The major losses of SOC over the entire hillslope are attributed to severe water erosion. Significant increase of SOC at the lower field boundaries on the summit and upper backslope resulted from tillage‐induced soil redistribution by moldboard plowing. Tillage‐induced soil redistribution increased SOC and compensated for 8–14% of the SOC losses due to water erosion during 1898–1998, but the total soil erosion reduced SOC pool over the steep cultivated hillslope of the Loess Plateau. During the period 1898–1954, the net SOC loss from the entire hillslope was 1.65 t C ha−1(0.03 t C ha−1yr−1). Within the period 1954–1998, the net SOC loss was 10.65 t C ha−1(0.24 t C ha−1yr−1). The positive relationship between SOC with137Cs and210Pbexconfirmed the utility of fallout radionuclides as a promising method for tracing tillage and water erosion impacts on SOC dynamics covering a timescale of 45 to 100 years.
Three‐dimensional structure of fluid conduits sustaining an active deep marine cold seep
Authors: Hornbach M. J. , Ruppel C. , Van Dover C. L.
Published: February 2007

Cold seeps in deep marine settings emit fluids to the overlying ocean and are often associated with such seafloor flux indicators as chemosynthetic biota, pockmarks, and authigenic carbonate rocks. Despite evidence for spatiotemporal variability in the rate, locus, and composition of cold seep fluid emissions, the shallow subseafloor plumbing systems have never been clearly imaged in three dimensions. Using a novel, high‐resolution approach, we produce the first three‐dimensional image of possible fluid conduits beneath a cold seep at a study site within the Blake Ridge gas hydrate province. Complex, dendritic features diverge upward toward the seafloor from feeder conduits at depth and could potentially draw flow laterally by up to 103 m from the known seafloor seep, a pattern similar to that suggested for some hydrothermal vents. The biodiversity, community structure, and succession dynamics of chemosynthetic communities at cold seeps may largely reflect these complexities of subseafloor fluid flow.
Stress and fluid transfer in a fault zone due to overpressures in the seismogenic crust
Authors: Cappa Frédéric , Guglielmi Yves , Virieux Jean
Published: February 2007

Stress and fluid transfers were analyzed on the surface of a 30 m thick dextral strike‐slip fault zone subjected to an overpressure of 63 kPa. Pressure‐strain measurements taken during the pressurization indicated a strain state primarily controlled by the hydromechanical behavior of permeable fractures, and then, by the fluid diffusion in the matrix. Using THM modeling, we simulated an extension of these hydromechanical effects to a 25 km depth in the seismogenic crust, applying a lithostatic pressure at the base of the fault. The simulations indicate that a significant strain in the damage zone greater than that in the protolith, along with the differences in hydraulic diffusivity between the damage zone and protolith, may induce high static stress and fluid accumulations in the core. Under this stress, this core is projected to exhibit deformity—as much as a 12 m shear slip distributed over a 175 m long active zone.
Determination of the height of the modulated electrojet region generating ELF radiation
Authors: Kuo Spencer P. , Greco Dimitrij
Published: February 2007

A virtual ionospheric antenna to generate ELF (extremely low frequency) waves is achievable by using amplitude modulated HF (high frequency) wave to modulate the electrojet current. The results of the numerical analysis show that the radiation intensities of ELF waves produced by modulated electrojet vary with the modulation frequency. Moreover, a ratio of two radiation intensities at two frequencies is height dependent. Thus, with the aid of the numerical results, the experimental measurements on the ratios of the radiation intensities of the ELF waves can provide unambiguous information on the height of the electrojet contributing to the ELF radiation. An experiment using the HAARP heating facility has been performed in 2005. The experimental results of three independent intensity ratios (25 Hz/205 Hz, 25 Hz/325 Hz, and 25 Hz/625 Hz) are used to demonstrate this new diagnostic technique. The height of the source region, where the modulated electrojet radiates most effectively, is determined to be between 94 Km and 97 Km.
Retrieval error estimation of surface albedo derived from geostationary large band satellite observations: Application to Meteosat‐2 and Meteosat‐7 data
Authors: Govaerts Y. M. , Lattanzio A.
Published: February 2007

The extraction of critical geophysical variables from multidecade archived satellite observations, such as those acquired by the European Meteosat First Generation satellite series, for the generation of climate data records is recognized as a pressing challenge by international environmental organizations. This paper presents a statistical method for the estimation of the surface albedo retrieval error that explicitly accounts for the measurement uncertainties and differences in the Meteosat radiometer characteristics. The benefit of this approach is illustrated with a simple case study consisting of a meaningful comparison of surface albedo derived from observations acquired at a 20 year interval by sensors with different radiometric performances. In particular, it is shown how it is possible to assess the magnitude of minimum detectable significant surface albedo change.
Endotoxin Preconditioning Protects against the Cytotoxic Effects of TNFα after Stroke: A Novel Role for TNFα in LPS-Ischemic Tolerance
Authors: Rosenzweig Holly L , Minami Manabu , Lessov Nikola S , Coste Sarah C , Stevens Susan L , Henshall David C , Meller Robert , Simon Roger P , Stenzel-Poore Mary P
Published: February 2007

Lipopolysaccharide (LPS) preconditioning provides neuroprotection against subsequent cerebral ischemic injury. Tumor necrosis factor-α (TNFα) is protective in LPS-induced preconditioning yet exacerbates neuronal injury in ischemia. Here, we define dual roles of TNFα in LPS-induced ischemic tolerance in a murine model of stroke and in primary neuronal cultures in vitro, and show that the cytotoxic effects of TNFα are attenuated by LPS preconditioning. We show that LPS preconditioning significantly increases circulating levels of TNFα before middle cerebral artery occlusion in mice and show that TNFα is required to establish subsequent neuroprotection against ischemia, as mice lacking TNFα are not protected from ischemic injury by LPS preconditioning. After stroke, LPS preconditioned mice have a significant reduction in the levels of TNFα (~ threefold) and the proximal TNFα signaling molecules, neuronal TNF-receptor 1 (TNFR1), and TNFR-associated death domain (TRADD). Soluble TNFR1 (s-TNFR1) levels were significantly increased after stroke in LPS-preconditioned mice (~ 2.5-fold), which may neutralize the effect of TNFα and reduce TNFα-mediated injury in ischemia. Importantly, LPS-preconditioned mice show marked resistance to brain injury caused by intracerebral administration of exogenous TNFα after stroke. We establish an in vitro model of LPS preconditioning in primary cortical neuronal cultures and show that LPS preconditioning causes significant protection against injurious TNFα in the setting of ischemia. Our studies suggest that TNFα is a twin-edged sword in the setting of stroke: TNFα upregulation is needed to establish LPS-induced tolerance before ischemia, whereas suppression of TNFα signaling during ischemia confers neuroprotection after LPS preconditioning.
Crystallographic space groups in geometric algebra
Authors: Hestenes David , Holt Jeremy W.
Published: February 2007

We present a complete formulation of the two-dimensional and three-dimensional crystallographic space groups in the conformal geometric algebra of Euclidean space. This enables a simple new representation of translational and orthogonal symmetries in a multiplicative group of versors. The generators of each group are constructed directly from a basis of lattice vectors that define its crystal class. A new system of space group symbols enables one to unambiguously write down all generators of a given space group directly from its symbol.
Coupled-cluster and explicitly correlated perturbation-theory calculations of the uracil anion
Authors: Bachorz Rafał A. , Klopper Wim , Gutowski Maciej
Published: February 2007

A valence-type anion of the canonical tautomer of uracil has been characterized using explicitly correlated second-order Møller-Plesset perturbation theory (RI-MP2-R12) in conjunction with conventional coupled-cluster theory with single, double, and perturbative triple excitations. At this level of electron-correlation treatment and after inclusion of a zero-point vibrational energy correction, determined in the harmonic approximation at the RI-MP2 level of theory, the valence anion is adiabatically stable with respect to the neutral molecule by 40meV. The anion is characterized by a vertical detachment energy of 0.60eV. To obtain accurate estimates of the vertical and adiabatic electron binding energies, a scheme was applied in which electronic energy contributions from various levels of theory were added, each of them extrapolated to the corresponding basis-set limit. The MP2 basis-set limits were also evaluated using an explicitly correlated approach, and the results of these calculations are in agreement with the extrapolated values. A remarkable feature of the valence anionic state is that the adiabatic electron binding energy is positive but smaller than the adiabatic electron binding energy of the dipole-bound state.
Stochastic estimation of a separated-flow field using wall-pressure-array measurements
Authors: Hudy Laura M. , Naguib Ahmed , Humphreys William M.
Published: February 2007

Concurrent, surface-pressure and planar, particle image velocimetry (PIV) measurements were obtained in the separating/reattaching flow region downstream of an axisymmetric, backward-facing step at a Reynolds number of 8081, based on step height. The surface-pressure and PIV measurements were used to investigate the evolution of coherent structures in the flow field by employing proper orthogonal decomposition (POD) and multipoint, linear, stochastic estimation (mLSE) analysis techniques. POD was used to determine the dominant modes in the pressure signature, while mLSE was used to estimate the dominant flow structures above the wall from the wall-pressure POD modes over a series of time steps. It was found that a large-scale, coherent structure develops in place (i.e., temporally) at approximately half the reattachment distance. Once this structure reaches a height equivalent to the step, it sheds and accelerates downstream. This growth in place, and then shedding, resembles the evolution of the flow structure in the wake of bluff bodies. Such a “wake mode” has been observed in numerical-simulation studies of long cavities and backward-facing steps, where flow two dimensionality is controllable. The present study shows for the first time evidence for the existence of a wake mode in an experimental study of a backward-facing step. This is believed to relate to the quality of the two dimensionality (i.e., axisymmetry) of the test geometry and the ability to track the temporal evolution of structural features through mLSE.
Si
O
x
∕
Si
radial superlattices and microtube optical ring resonators
Authors: Songmuang R. , Rastelli A. , Mendach S. , Schmidt O. G.
Published: February 2007

Scanning and transmission electron microscopy reveals that SiOx∕Si layers can roll up into microtubes and radial superlattices on a Si substrate. These hybrid objects are thermally stable up to 850°C and emit light in the visible spectral range at room temperature. For tubes disengaged from the substrate surface, optically resonant emissions with mode spacings inversely proportional to the tube diameter are observed and agree excellently with those obtained from finite-difference time-domain simulations. The resonant modes recorded are strictly polarized along the tube axis.
Statistical analysis of electromigration lifetimes and void evolution
Authors: Hauschildt M. , Gall M. , Thrasher S. , Justison P. , Hernandez R. , Kawasaki H. , Ho P. S.
Published: February 2007

Electromigration failure statistics and the origin of the log-normal standard deviation for copper interconnects were investigated by analyzing the statistics of electromigration lifetime and void size distributions at various stages during testing. Experiments were performed on 0.18μm wide Cu interconnects with tests terminated after certain amounts of resistance increase, or after a specified test time. The lifetime and void size distributions were found to follow log-normal distribution functions. The sigma values of these distributions decrease with increasing test time. The statistics of resistance-based void size distributions can be simulated by considering geometrical variations of the void shape. In contrast, the characteristics of time-based void size distributions require consideration of kinetic aspects of the electromigration process. The sigma values of lifetime distributions can be adequately simulated by combining the statistics of both types of void size distributions. Thus, a statistical correlation between electromigration lifetimes and void evolution was established. Using simulation to fit the experimental data, the parameters influencing the electromigration lifetime statistics were identified as variations in void sizes, geometrical and experimental factors of the electromigration experiment, and kinetic aspects of the mass transport process, such as differences in interface diffusivity between the lines. The latter is the result of variations in the copper microstructure at the cathode ends of the interconnects.
High temperature integrated ultrasonic shear and longitudinal wave probes
Authors: Ono Y. , Jen C.-K. , Kobayashi M.
Published: February 2007

Integrated ultrasonic shear wave probes have been designed and developed using a mode conversion theory for nondestructive testing and characterization at elevated temperatures. The probes consisted of metallic substrates and high temperature piezoelectric thick (>40μm) films through a paint-on method. Shear waves are generated due to mode conversion from longitudinal to shear waves because of reflection inside the substrate having a specific shape. A novel design scheme is proposed to reduce the machining time of substrates and thick film fabrication difficulty. A probe simultaneously generating and receiving both longitudinal and shear waves is also developed and demonstrated. In addition, a shear wave probe using a clad buffer rod consisting of an aluminum core and stainless steel cladding has been developed. All the probes were tested and successfully operated at 150°C.
Reduction in operation voltage of complementary organic thin-film transistor inverter circuits using double-gate structures
Authors: Hizu Kazuki , Sekitani Tsuyoshi , Someya Takao , Otsuki Joe
Published: February 2007

The authors have fabricated organic inverters comprising p-type pentacene and n-type fluoroalkyl naphthalenetetracarboxylic di-imide thin-film transistors (TFTs). The TFTs have double-gate structures that independently control the threshold voltage of the p- and n-type TFTs. The mobilities of the p- and n-type transistors are 0.18 and 0.09cm2∕Vs, respectively. Both the as-manufactured p- and n-type TFTs exhibit depletion-type behavior, which can be changed to enhancement-type behavior by applying a voltage bias to the top-gate electrodes. By controlling the top-gate biases, the operation voltage of the organic inverter circuits can be systematically reduced to 5V.
Highly intense violet-blue light emission at room temperature in structurally disordered SrZrO3 powders
Authors: Longo V. M. , Cavalcante L. S. , de Figueiredo A. T. , Santos L. P. S. , Longo E. , Varela J. A. , Sambrano J. R. , Paskocimas C. A. , De Vicente F. S. , Hernandes A. C.
Published: February 2007

Violet-blue photoluminescence was produced at room temperature in a structurally disordered SrZrO3 perovskite structure with a 350.7nm excitation line. The intensity of this emission was higher than that of any other perovskites previously studied. The authors discuss the role of structural order-disorder that favors the self-trapping of electrons and charge transference, as well as a model to elucidate the mechanism that triggers photoluminescence. In this model the wide band model, the most important events occur before excitation.
Enhanced plasmon coupling in crossed dielectric/metal nanowire composite geometries and applications to surface-enhanced Raman spectroscopy
Authors: Prokes S. M. , Glembocki O. J. , Rendell R. W. , Ancona M. G.
Published: February 2007

Surface-enhanced Raman spectroscopy (SERS) was performed on Ga2O3∕Ag and ZnO∕Ag nanowires, which were arranged in either a crossover or noncrossing geometry. Results indicate a high SERS sensitivity (near 0.2pg) for nanowires arranged in a crossing geometry. It is suggested that this is due to the dielectric core/metal shell structure, as well as to the nanowire crossings, which are regions of very high electric fields. Finite element simulations of the electric field near two crossed wires confirm an enhanced plasmon resonance in the vicinity of the crossing, which extends spatially in the crossings and around the nanowires.
Near-infrared to visible light optical upconversion by direct tandem integration of organic light-emitting diode and inorganic photodetector
Authors: Ban D. , Han S. , Lu Z. H. , Oogarah T. , SpringThorpe A. J. , Liu H. C.
Published: February 2007

The authors report a hybrid organic/inorganic optical upconversion device that converts 1.5μm infrared light to ∼520nm visible light. The device was made by direct tandem integration of an inorganic InGaAs∕InP photodetector with an organic light-emitting diode (OLED). Optical upconversion with an external efficiency of 0.7% W/W at room temperature has been achieved. Interfacial structure at the inorganic-organic interface was found to play a vital role in enabling the integration of the hybrid tandem upconverter. Both sulfur-terminated InP surface and nanocarbon fullerene interlayer were found crucial to form a good interface contact, permitting continuous flow of photocarriers from the inorganic detector into the OLED.
Enhancement-mode metal-semiconductor field-effect transistors based on single n-CdS nanowires
Authors: Ma R. M. , Dai L. , Qin G. G.
Published: February 2007

Enhancement-mode (E-mode) metal-semiconductor field-effect transistors (MESFETs) based on single nanowires (NWs) were reported. The single NW used is n-CdS NW. Source-drain channel of the nano-MESFET is pinched off by the top surrounding Schottky gate at zero bias. When Schottky gate voltage (VG) changes from 0to0.25V, the source-drain current increases exponentially with VG, and an on/off current ratio of 5×103 is obtained. The maximum transconductance is 14.6nA∕V, and the gate leakage current is lower than source-drain current by more than two orders of magnitude. Their results suggest a way of fabricating E-mode nano-field-effect transistors.
Set-Size Effects in Simple Visual Search for Contour Curvature
Authors: Sakai Koji , Morishita Masanao , Matsumoto Hirofumi
Published: February 2007

In a visual-search paradigm, both perception and decision processes contribute to the set-size effects. Using yes – no search tasks in set sizes from 2 to 8 for contour curvature, we examined whether the set-size effects are predicted by either the limited-capacity model or the decision-noise model. There are limitations in perception and decision-making in the limited-capacity model, but only in decision-making in the decision-noise model. The results of four experiments showed that the slopes of the logarithm of threshold plotted against the logarithm of set size ranged from 0.24 to 0.32, when the curvature was high or low, contour convexity was upward or downward, and stimulus was masked or unmasked. These slopes were closer to the prediction of 0.23 by the decision-noise model than that of 0.73 by the limited-capacity model. We interpret this that in simple visual search for contour curvature, the decision noise mainly affects the set-size effects and perceptual capacity is not limited.
Electrostatic gating of a nanometer water channel
Authors: Li Jingyuan , Gong Xiaojing , Lu Hangjun , Li Ding , Fang Haiping , Zhou Ruhong
Published: February 2007

Water permeation across a single-walled carbon nanotube (SWNT) under the influence of a mobile external charge has been studied with molecular dynamics simulations. This designed nanopore shows an excellent on–off gating behavior by a single external charge (of value +1.0e): it is both sensitive to the available charge signal when it is close (less than a critical distance of 0.85 Å or about half the size of a water molecule) and effectively resistant to charge noise, i.e., the effect on the flow and net flux across the channel is found to be negligible when the charge is >0.85 Å away from the wall of the nanopore. This critical distance can be estimated from the interaction balance for the water molecule in the SWNT closest to the imposed charge with its neighboring water molecules and with the charge. The flow and net flux decay exponentially with respect to the difference between these two interaction energies when the charge gets closer to the wall of the SWNT and reaches a very small value once the charge crosses the wall, suggesting a dominating effect on the permeation properties from local water molecules near the external charge. These findings might have biological implications because membrane water channels share a similar single-file water chain inside these nanoscale channels.
Targeted deletion of
Wwox
reveals a tumor suppressor function
Authors: Aqeilan Rami I. , Trapasso Francesco , Hussain Sadiq , Costinean Stefan , Marshall Dean , Pekarsky Yuri , Hagan John P. , Zanesi Nicola , Kaou Mohamed , Stein Gary S. , Lian Jane B. , Croce Carlo M.
Published: February 2007

The WW domain-containing oxidoreductase (
WWOX
) spans the second most common fragile site of the human genome,
FRA16D
, located at 16q23, and its expression is altered in several types of human cancer. We have previously shown that restoration of WWOX expression in cancer cells suppresses tumorigenicity. To investigate WWOX tumor suppressor function
in vivo
, we generated mice carrying a targeted deletion of the
Wwox
gene and monitored incidence of tumor formation. Osteosarcomas in juvenile
Wwox
−/−
and lung papillary carcinoma in adult
Wwox
+/−
mice occurred spontaneously. In addition,
Wwox
+/−
mice develop significantly more ethyl nitrosourea-induced lung tumors and lymphomas in comparison to wild-type littermate mice. Intriguingly, these tumors still express Wwox protein, suggesting haploinsuffiency of WWOX itself is cancer predisposing. These results indicate that WWOX is a bona fide tumor suppressor.
Loss of endocytic clathrin-coated pits upon acute depletion of phosphatidylinositol 4,5-bisphosphate
Authors: Zoncu Roberto , Perera Rushika M. , Sebastian Rafael , Nakatsu Fubito , Chen Hong , Balla Tamas , Ayala Guillermo , Toomre Derek , De Camilli Pietro V.
Published: February 2007

Phosphatidylinositol 4,5-bisphosphate [PI(4,5)
P
2
], a phosphoinositide concentrated predominantly in the plasma membrane, binds endocytic clathrin adaptors, many of their accessory factors, and a variety of actin-regulatory proteins. Here we have used fluorescent fusion proteins and total internal reflection fluorescence microscopy to investigate the effect of acute PI(4,5)
P
2
breakdown on the dynamics of endocytic clathrin-coated pit components and of the actin regulatory complex, Arp2/3. PI(4,5)
P
2
breakdown was achieved by the inducible recruitment to the plasma membrane of an inositol 5-phosphatase module through the rapamycin/FRB/FKBP system or by treatment with ionomycin. PI(4,5)
P
2
depletion resulted in a dramatic loss of clathrin puncta, which correlated with a massive dissociation of endocytic adaptors from the plasma membrane. Remaining clathrin spots at the cell surface had only weak fluorescence and were static over time. Dynamin and the p20 subunit of the Arp2/3 actin regulatory complex, which were concentrated at late-stage clathrin-coated pits and in lamellipodia, also dissociated from the plasma membrane, and these changes correlated with an arrest of motility at the cell edge. These findings demonstrate the critical importance of PI(4,5)
P
2
in clathrin coat dynamics and Arp2/3-dependent actin regulation.
Fusion of proinsulin-producing bone marrow-derived cells with hepatocytes in diabetes
Authors: Fujimiya Mineko , Kojima Hideto , Ichinose Masumi , Arai Ryohachi , Kimura Hiroshi , Kashiwagi Atsunori , Chan Lawrence
Published: February 2007

We previously reported that diabetes in mice is associated with the appearance of proinsulin-producing (Proins-P) cells in the liver. It was unclear, however, whether these Proins-P bone marrow-derived cells (BMDC) merely transit through the liver or undergo fusion with hepatocytes, normally an extremely rare event. In this study, we found that, in diabetes, BMDC in the liver produce not only Proins but also TNF-α, suggesting that diabetes reprograms gene expression in BMDC, turning on “inappropriate” genes. Bone marrow transplantation using genetically marked donor and recipient mice showed that fusion occurs between Proins-P BMDC and hepatocytes. Cell fusion is further supported by the presence of the Y chromosome in Proins-P cells in female mice that received male bone marrow transplantation cells. Morphologically, Proins-P fusion cells are albumin-producing hepatocytes that constitute ≈2.5% of the liver section area 5 months after diabetes induction. An extensive search failed to reveal any fusion cells in nondiabetic mice. Thus, diabetes causes fusion between Proins-P BMDC and hepatocytes
in vivo
, an observation that has implications for the pathophysiology of diabetes as well as the fundamental biology of heterotypic cell fusion.
Trends in Ventilator-Associated Pneumonia Rates Within the German Nosocomial Infection Surveillance System (KISS)
Authors: Zuschneid I. , Schwab F. , Gastmeier P. , Geffers C. , Behnke M. , Rüden H.
Published: February 2007

Objective.

To investigate trends in ventilator-associated pneumonia (VAP) rates during participation in the German nosocomial infection surveillance system (Krankenhaus-Infektions-Surveillance-System [KISS]).

Methods.

A total of 71 ICUs that began participating in KISS in 1999 or later and continued participation for at least 36 months were selected. Beginning with the first month of participation, the pooled mean rate of VAP in the ICUs was calculated for each year of participation. The incidence densities for the 3 years of participation were compared using the Pearson x2 test. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated. VAP rates were calculated for each ICU and year of participation, and rates for years 1 and 3 were compared using the Wilcoxon test for paired samples.

Results.

Twenty-nine medical-surgical, 18 medical, 20 surgical, 2 neurosurgical, and 2 pediatric ICUs met the selection criteria. Surveillance data were available on 181,275 patients, for whom there were 613,098 patient-days and 224,138 ventilator-days. A total of 2,043 cases of VAP were reported. The ICUs had a pooled VAP rate of 10.5 cases per 1,000 ventilator-days during year 1 of KISS surveillance. In year 2, the rate decreased by 19%, to 8.7 cases per 1,000 ventilator-days (RR, 0.81 [95% CI, 0.73-0.90]). In year 3, the rate decreased by 24% from year 1, to 8.0 cases per 1,000 ventilator-days (RR, 0.76; 95% CI, 0.68-0.85). Both results were significant (P < .001 by the Pearson x2 test). Comparison of the VAP rates of the ICUs did not show a significant difference between years 1 and 3 of KISS participation.

Conclusion.

Surveillance was associated with a significant reduction in the pooled rate of VAP during years 1-3 of KISS participation.
Influence of Rings on the Efficacy of Hand Sanitization and Residual Bacterial Contamination
Authors: Wongworawat Montri D. , Jones Sidney G.
Published: February 2007

Background.

Previous studies, conducted before widespread use of scrubless, alcohol-based hand sanitizers, demonstrated increased residual bacterial counts after hand hygiene on hands with jewelry.

Objective.

To compare the impact of finger rings on the effectiveness of scrubless and water-aided alcohol-based hand sanitization methods with that of povidone-iodine scrub.

Design.

Randomized, controlled study.

Setting.

University hospital.

Participants.

Sixty volunteer subjects from a pool of perioperative staff and medical students.

Intervention.

After recruitment, participants wore a ring on one hand and no ring on the other hand. They were randomly assigned to perform hand hygiene with a povidone-iodine scrub, an alcohol wash, or a waterless alcohol-chlorhexidine lotion (n = 20 subjects per method). After subjects completed hand hygiene, gloves were placed on their hands by means of sterile methods, and a “glove juice” technique was used to obtain samples for culture. The number of colony-forming units in each culture was counted, and the data were compared.

Results.

There was no significant difference in the number of bacteria between hands with and hands without rings for the groups that used alcohol wash or alcohol-chlorhexidine lotion. However, for the povidone-iodine group, the number of bacteria on hands with rings was greater than the number on hands without rings (P < .05). The hands of participants who used waterless alcohol-chlorhexidine had the lowest bacterial count, regardless of the presence of rings (P < .01).

Conclusions.

The presence of rings does not negatively impact the effectiveness of alcohol-based hand sanitizers. Use of waterless alcohol-chlorhexidine lotion resulted in the lowest bacterial count.
Population Kinetics of the Skin Flora on Gloved Hands Following Surgical Hand Disinfection With 3 Propanol-Based Hand Rubs: A Prospective, Randomized, Double-Blind Trial
Authors: Rotter Manfred L. , Kampf Günter , Suchomel Miranda , Kundi Michael
Published: February 2007

Objective.

To study the bacterial population kinetics on gloved hands following hand treatment with 3 optically indistinguishable, alcohol-based surgical hand rubs, with and without supplements to delay bacterial regrowth.

Design.

Prospective, randomized, double-blind, balanced quasi-Greco-Latin square design.

Setting.

Microbiology laboratory of the Medical University Vienna, Austria.

Participants.

Twenty-four healthy adult volunteers without skin lesions.

Surgical Hand Rubs.

The following hand rubs, all stained blue, were applied to the hands for 3 minutes: 1-propanol 60% vol/vol (A); 2-propanol 70% m/m plus chlorhexidine gluconate 0.5% wt/wt (B); 2-propanol 45% wt/wt plus 1-propanol 30% wt/wt plus mecetronium etilsulfate 0.2% wt/wt (C). As a reference formulation (R), 1-propanol 60% vol/vol, unstained, was applied for the same amount of time.

Method.

In 8 once-weekly tests, 24 subjects randomly assigned to use the 4 hand rubs in groups of 6 persons each performed hand hygiene according to the method described in European Norm 12791. Every subject used one preparation at a time, the antimicrobial effect of which was evaluated at 2 sampling times. After week 8, each volunteer had tested every preparation at every preset sampling time. All preparations were tested in parallel.

Results.

The mean pretreatment counts of viable bacteria (in colony-forming units per milliliter) in fluid samples were not significantly different between week 1 and week 8, nor between the right and left hands (analysis of variance [ANOVA], P > .1). Immediately after applying the formulation (t0), bactericidal effects of the blinded formulations A and C were equivalent to that of the reference formulation R, whereas the effect of B was questionable. The population kinetics of the flora on the hands proceeded from large and fast initial reductions of the skin flora by 2.7 log units (A), 3.1 log units (B), 3.3 log units (reference formulation), and 3.5 log units (C), to slow regrowth. However, even after 6 hours wearing gloves viable bacterial counts remained significantly (P < .01) below the baseline values (by 0.9 log [reference formulation], 1.1 log [A and B], and 1.5 log [C]). The slowest regrowth 1 and 3 hours after application (∆ from t0, 0.1 log and 0.7 log respectively) was seen with formulation C, and the slowest regrowth after 6 hours was seen with formulation B (∆ from t0, 1.6 log). These differences did, however, not reach statistical significance.

Conclusions.

With respect to the rapid and dramatic antibacterial action of suitable alcohols at high concentrations and with appropriate neutralizers, the contribution of supplements to the delay of bacterial regrowth on gloved hands appears rather minor, if a product only exerts an immediate effect equivalent to that of the reference disinfection procedure described in EN 12791.