bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of thenardite on the direct detection of aromatic amino acids: implications for the search for life in the solar system
Authors: Doc Richardson C. , Hinman Nancy W. , Scott Jill R.
Published: August 2009

With the discovery of Na-sulphate minerals on Mars and Europa, recent studies using these minerals have focused on their ability to assist in the detection of bio/organic signatures. This study further investigates the ability of thenardite (Na2SO4) to effectively facilitate the ionization and identification of aromatic amino acids (phenylalanine, tyrosine and tryptophan) using a technique called geomatrix-assisted laser desorption/ionization in conjunction with a Fourier transform ion cyclotron resonance mass spectrometry. This technique is based on the ability of a mineral host to facilitate desorption and ionization of bio/organic molecules for detection. Spectra obtained from each aromatic amino acid alone and in combination with thenardite show differences in ionization mechanism and fragmentation patterns. These differences are due to chemical and structural differences between the aromatic side chains of their respective amino acid. Tyrosine and tryptophan when combined with thenardite were observed to undergo cation-attachment ([M+Na]+), due to the high alkali ion affinity of their aromatic side chains. In addition, substitution of the carboxyl group hydrogen by sodium led to formation of [M-H+Na]Na+ peaks. In contrast, phenylalanine mixed with thenardite showed no evidence of Na+ attachment. Understanding how co-deposition of amino acids with thenardite can affect the observed mass spectra is important for future exploration missions that are likely to use laser desorption mass spectrometry to search for bio/organic compounds in extraterrestrial environments.
Choice and competition in publicly funded health care
Authors: LE GRAND JULIAN
Published: August 2009

There are four basic models of health service delivery: those that rely on trust, on command and control, on voice, and on choice and competition. All have their merits and demerits; but there are both theoretical and empirical arguments for preferring choice and competition in many situations. However, the relevant policies do have to be properly designed.
The case against choice and competition
Authors: HUNTER DAVID J.
Published: August 2009

Choice and competition are central planks of the English government’s health reforms and modernisation programme. Wales and Scotland have chosen a different path, which calls into question the suggestion that in an age of consumerism there is no other way to secure overdue changes in the provision and management of health care to improve their quality and responsiveness to user preferences. Yet pro-market enthusiasts pursue their agenda in the face of evidence that calls into question the claims they make. It is a curious position for a government that is wedded to evidence-based policy to find itself in. The policy puzzle is why, despite the contested nature of the alleged virtues of choice and competition, policy-makers persist with introducing a set of reforms which appear to threaten the very values and principles they profess to uphold. An alternative reform paradigm exists which acknowledges what makes public services public. This paper sets out the key features of what rediscovering public service entails adopting the notion of co-production as a means of bringing about a new relationship between professionals and the public that remains true to the National Health Service’s social purpose.
Does competition among general practitioners increase or decrease the consumption of specialist health care?
Authors: Tjerbo Trond
Published: August 2009

Studies of the effects of capacity and competition among general practitioners (GPs) on the use of specialist health care services are inconclusive. Some studies indicate that an increase in the number of GPs leads to increased consumption of specialist health care, while other studies point in the opposite direction. This article adds to the literature in two ways; first by testing out different operationalization of capacity and competition among GPs, and then by testing out effects of capacity and competition on use of specialist health care services as this is disaggregated into ambulatory and inpatient activities. The empirical tests indicate that GP capacity in itself does not affect use of specialist health care services. Increased competitions among GPs do, however, reduce the use of ambulatory care while the effects on the use of inpatient services are unaffected.
Impacts of increasing anthropogenic soluble iron and nitrogen deposition on ocean biogeochemistry
Authors: Krishnamurthy Aparna , Moore J. Keith , Mahowald Natalie , Luo Chao , Doney Scott C. , Lindsay Keith , Zender Charles S.
Published: August 2009

We present results from transient sensitivity studies with the Biogeochemical Elemental Cycling (BEC) ocean model to increasing anthropogenic atmospheric inorganic nitrogen (N) and soluble iron (Fe) deposition over the industrial era. Elevated N deposition results from fossil fuel combustion and agriculture, and elevated soluble Fe deposition results from increased atmospheric processing in the presence of anthropogenic pollutants and soluble Fe from combustion sources. Simulations with increasing Fe and increasing Fe and N inputs raised simulated marine nitrogen fixation, with the majority of the increase in the subtropical North and South Pacific, and raised primary production and export in the high‐nutrient low‐chlorophyll (HNLC) regions. Increasing N inputs alone elevated small phytoplankton and diatom production, resulting in increased phosphorus (P) and Fe limitation for diazotrophs, hence reducing nitrogen fixation (∼6%). Globally, the simulated primary production, sinking particulate organic carbon (POC) export. and atmospheric CO2 uptake were highest under combined increase in Fe and N inputs compared to preindustrial control. Our results suggest that increasing combustion iron sources and aerosol Fe solubility along with atmospheric anthropogenic nitrogen deposition are perturbing marine biogeochemical cycling and could partially explain the observed trend toward increased P limitation at station ALOHA in the subtropical North Pacific. Excess inorganic nitrogen ([NO3−] + [NH4+] − 16[PO43−]) distributions may offer useful insights for understanding changing ocean circulation and biogeochemistry.
Numerical modeling of two‐phase flow in the NaCl‐H2O system: 2. Examples
Authors: Lewis K. C. , Lowell R. P.
Published: August 2009

In an earlier paper, we presented a new multiphase numerical code for NaCl‐H2O fluid called FISHES. Here we present some example simulations using FISHES that show its applicability to 1‐D and 2‐D geometries that are commonly used in describing two‐phase hydrothermal flows. We simulate a 1‐D heat pipe with an open top upper boundary in order to study mass and energy balance properties within a region of phase separating fluid. The results show the formation of a dense brine layer at the base of the heat pipe as a two‐phase zone expands toward the top. We then simulate 2‐D circulation in a single‐pass geometry with a highly permeable discharge zone, a geometry that has often been used in the study of seafloor hydrothermal systems. We show that when active phase separation occurs at the base of the system, low‐salinity fluid emerges from the top as a dense brine layer forms at the base and that increased vent fluid temperatures result from decreasing the width of the discharge pipe. Following a period of active phase separation, we show that lowering the basal temperature results in flushing the brine from the system on a time scale similar to the period of active phase separation. Lowering the permeability does not significantly affect vent fluid salinities during active subsurface phase separation but inhibits the flushing of brine upon lowering of basal temperatures; also, low permeabilities increase the time scale for the evolution of the system. Finally, we conduct simulations of two‐phase flow in rectangular 1 km2 homogeneous fluid‐saturated open top boxes heated from below with permeabilities of 10−12 and 10−13 m2. During these simulations a strong plume forms above the region of strong lateral temperature change, and brine collects at the base of the system. Initially, low‐salinity fluids vent from the top of the box; eventually, higher‐salinity fluids emerge. Vent fluid salinities and temperatures associated with plumes vary with time, resulting in larger temporal variation in fluid properties than those obtained from single‐pass simulations.
Controls on iron distributions in the deep water column of the North Pacific Ocean: Iron(III) hydroxide solubility and marine humic‐type dissolved organic matter
Authors: Kitayama Saori , Kuma Kenshi , Manabe Eri , Sugie Koji , Takata Hyoe , Isoda Yutaka , Toya Kenji , Saitoh Sei‐ichi , Takagi Shohgo , Kamei Yoshihiko , Sakaoka Keiichiro
Published: August 2009

Dissolved Fe in the western and central North Pacific Ocean was characterized by surface depletion, middepth maxima and, below that, a slight decrease with depth similar to the vertical distributions of nutrients, apparent oxygen utilization, Fe(III) hydroxide solubility, and humic‐type fluorescence (H‐flu) intensity. Dissolved Fe concentrations ([D‐Fe], <0.22‐μm fraction) in the deep water column were one‐half lower in the central region (0.3–0.6 nM) than the western region (0.5–1.2 nM) although the Fe(III) solubility ([Fe(III)sol], <0.025‐μm fraction) levels and distributions in deep waters were almost the same between both regions with middepth maxima (∼0.6 nM) at 500–1500‐m depth range and then a gradual decrease to ∼0.3 nM at 5000‐m depth. Higher [D‐Fe] than [Fe(III)sol] in the deep water column of the western region results from the higher production of dissolved Fe from the decomposition of sinking particulate organic matter in the western region than the central region because of the high atmospheric and/or lateral Fe inputs in the western region. Similarity between [D‐Fe] level and [Fe(III)sol] value at each deep water depth in the central region may be attributed to [D‐Fe] being nearly in the solubility equilibrium with Fe(III) hydroxide in seawater. Strong linear correlation between [D‐Fe] and H‐flu intensity in the central region and relatively similar linear relationships between [Fe(III)sol] and H‐flu intensity in the western and central regions are the first confirmation that humic‐type fluorescent dissolved organic matter may be responsible for [D‐Fe] in the deep water column as natural organic ligands complexing with Fe(III).
Influence of steady base‐level rise on channel mobility, shoreline migration, and scaling properties of a cohesive experimental delta
Authors: Martin John , Sheets Ben , Paola Chris , Hoyal David
Published: August 2009

Here we describe results from an alluvial delta physical experiment with and without steady base‐level rise. Using a unique cohesive sediment mixture that promotes the development of persistent channels and a rugose shoreline, we quantitatively characterize channel network properties as a function of base‐level rise in a distributary system that reproduces many aspects of the geometry of natural deltas. Analysis of the experimental data shows clear dynamical differences between the predominantly progadational and aggradational phases of the experiment. The experiment was conducted in two phases: a first in which the delta prograded into standing water of constant depth in the absence of base‐level rise and a second during which steady base‐level rise was imposed on the system, forcing a twofold increase in topset aggradation due to greater sediment retention in the fluvial reach. The shift in sediment mass balance to enhanced fluvial deposition in the second phase caused channel network mobility to increase, reducing the autogenic channel time scale from 23.5 to 12.5 h and supporting a positive correlation between deposition and channel avulsion frequency. An independent shoreline time scale that characterizes the dominant time over which shoreline regression is persistent closely correlates with measurements of the channel network (28.3 h during fan progradation and 9.5 h during fan aggradation). These metrics suggest a strong coupling between channel network and shoreline kinematics and a more active fluvial surface during fan aggradation by a factor of 2 to 3, similar to the increase in aggradation rate. Spatial scaling of shoreline roughness reveals that maximum shoreline variability is set by the scale of distributary lobes. Strong coupling exists between delta growth and shoreline geometry during progradation. During aggradation, however, shoreline variability is not solely due to distributary lobe growth but is also set by shoreline transgression over inactive portions of the delta, illustrating a decoupling between fan kinematics and fan geometry. This decoupling, together with the matched increase in channel network mobility and fluvial aggradation, suggest the stratigraphic architecture may not be a strong geometric signal of different fluvial surface conditions either.
Vertical air motion in midlevel shallow‐layer clouds observed by 47‐MHz wind profiler and 532‐nm Mie lidar: Initial results
Authors: Yamamoto Masayuki K. , Abo Makoto , Kishi Toyohisa , Nishi Noriyuki , Seto Tri Handoko , Hashiguchi Hiroyuki , Yamamoto Mamoru , Fukao Shoichiro
Published: August 2009

Variations of vertical air velocity (W) in the midlevel shallow‐layer clouds are described by a case study observed at West Sumatra, Indonesia (0.2°S, 100.32°E), in the nighttime between 8 and 9 May 2004. By receiving echoes from refractive index irregularities, W and spectral width (σW), used as a proxy of W turbulence, were observed both in clear and cloud regions using frequency power spectrum obtained by a 47‐MHz wind profiler with 150‐m vertical and 166‐s time resolutions. Using altitude profiles of received signal intensity of a 532‐nm Mie lidar (Plidar), altitudes with significantly larger Plidar than below (or above) were considered as cloud regions. Most of the shallow‐layer clouds were observed between 6.0 and 8.5 km. In the top part of clouds (∼0–500 m below the estimated cloud tops), downward W up to ∼0.2–0.3 m s−1 and σW up to ∼0.5–0.6 m s−1 were observed. In the middle part of clouds (∼500–1000 m below the estimated cloud tops), W showed large variations. Both the standard deviation of W during the observation period and σW were large (∼0.5–0.7 m s−1). These results demonstrate that a combination of VHF wind profiler and lidar is useful to observe wind variations in and around midlevel shallow‐layer clouds with high time and vertical resolutions. Altitude profiles of temperature observed by radiosondes showed that the air was absolutely stable near the top part of clouds and conditionally stable below. Possible relationship between W and temperature is discussed.
Impact of megathrust geometry on inversion of coseismic slip from geodetic data: Application to the 1960 Chile earthquake
Authors: Moreno M. S. , Bolte J. , Klotz J. , Melnick D.
Published: August 2009

We analyze the role of megathrust geometry on slip estimation using the 1960 Chile earthquake (MW = 9.5) as an example. A variable slip distribution for this earthquake has been derived by Barrientos and Ward (1990) applying an elastic dislocation model with a planar fault geometry. Their model shows slip patches at 80–110 km depth, isolated from the seismogenic zone, interpreted as aseismic slip. We invert the same geodetic data set using a finite element model (FEM) with precise geometry derived from geophysical data. Isoparametric FEM is implemented to constrain the slip distribution of curve‐shaped elements. Slip resolved by our precise geometry model is limited to the shallow region of the plate interface suggesting that the deep patches of moment were most likely an artifact of the planar geometry. Our study emphasizes the importance of fault geometry on slip estimation of large earthquakes.
Using ground‐based GPS to characterize atmospheric turbulence
Authors: Nilsson T. , Davis J. L. , Hill E. M.
Published: August 2009

A new method for measuring and studying atmospheric turbulence is presented. The method uses data from a local network of GPS receivers. The GPS data are processed in a way that assures that the estimated zenith total delays (ZTD) contain the effects of atmospheric turbulence present in the GPS observations. The turbulence is characterized using the spatial structure function for the atmospheric zenith total delay. The structure function is modeled by an expression with unknown parameters which contains information about the turbulence. The unknown parameters are solved by a fit to the observed ZTD variations. We apply the method to GPS data from the Yucca Mountain network, Nevada, USA. The results show that the magnitude of the turbulent variations in that region have a strong seasonal dependence, with much larger variations in summer compared to winter.
Deciphering the rate of mountain growth during topographic presteady state: An example from the NE margin of the Tibetan Plateau
Authors: Palumbo Luigi , Hetzel Ralf , Tao Mingxin , Li Xiaobin , Guo Jianming
Published: August 2009

We use field investigations, topographic profiles, and 10Be exposure dating to constrain the growth rate of the Yumu Shan, a thrust‐bounded mountain range at the northeastern margin of Tibet. Wind gaps, fault scarps at the mountain front, and hanging paleocatchments indicate that the Yumu Shan is growing both laterally and vertically. Scarp profiles and 10Be ages yield rock uplift rates of ∼500 and ∼800 mm ka−1 for the eastern and central parts of the range, respectively. The fact that the rock uplift rate in the high center of the Yumu Shan exceeds catchment‐wide 10Be denudation rates, which range from ∼180 to ∼280 mm ka−1, indicates that the mountain range continues to rise and has not yet reached a topographic steady state. Combining the total structural relief of the range with the rates of rock uplift and denudation suggests that the growth of the Yumu Shan started 3.7 ± 0.9 Ma ago.
Child Overweight, Associated Psychopathology, and Social Functioning: A French School‐based Survey in 6‐ to 11‐year‐old Children
Authors: Pitrou Isabelle , Shojaei Taraneh , Wazana Ashley , Gilbert Fabien , Kovess‐Masféty Viviane
Published: August 2009

The aim of this study was to estimate the prevalence of child overweight in a regional sample of primary school‐aged children, and to examine the relationships among child overweight, psychopathology, and social functioning. A cross‐sectional survey was conducted in 2004 in 100 primary schools of a large French region, with 2,341 children aged 6–11 randomly selected. Child weight and height, lifestyle variables (leisure‐time physical activity (LTPA), watching television (TV), playing video games), and socioeconomic characteristics were collected in parent‐administered questionnaires. Child psychopathology outcomes were assessed using child‐ and parent‐reported instruments (Dominic Interactive (DI) and Strengths and Difficulties Questionnaire (SDQ)). Overweight and obesity were estimated according to the International Obesity Task Force (IOTF) definition. Response rates to the parent questionnaire and DI were 57.4 and 95.1%, respectively. Final sample size was 1,030 children. According to the IOTF, 17.3% of the children were overweight, of whom 3.3% were obese. In univariate analysis, correlates of overweight were low parental education, low monthly income, Disadvantaged School Areas (DSAs), self‐reported generalized anxiety, parent‐reported conduct disorders, emotional problems, and peer difficulties. High monthly income was less frequently associated with overweight. In multivariate analysis, parent‐reported peer difficulties (odds ratio (OR) = 2.06; 95% confidence interval = 1.27–3.35) and DSAs (1.88; 1.03–3.44) were independent factors significantly associated with child overweight. There was a trend of being overweight with elevated TV times (P for trend = 0.02). The psychosocial burden of excess weight appears to be significant even in young children. Findings should be considered for preventing strategies and public health interventions. School‐based overweight prevention programs should be implemented first in disadvantaged areas together with information about weight stigmatization and discrimination.
Level alignment of gap state at organic-metal interface
Authors: Aoki M. , Toyoshima S. , Kamada T. , Sogo M. , Masuda S. , Sakurai T. , Akimoto K.
Published: August 2009

Electron emission spectra resulting from thermal collision of He∗(23S) atoms with 2,9-demethyl-4,7-diphenyl-1,10-phenanthroline (BCP) films deposited on metal substrates were measured to characterize gap states emerged at the organic-metal interface. For BCP on Au, the gap state is originated from weak chemisorption and serves as a mediator of metal wave functions to the first layer. For BCP on K, organic-metal complex is formed by spontaneous diffusion, yielding the gap states delocalized over the film. In the interfacial region, all the gap state reveals an incommensurate shift with the valence band top of the film, indicating the breakdown of the Schottky–Mott model as evaluating the transport characteristics in organic-metal system.
Parametric study of expanding plasma plume formed by laser-blow-off of thin film using triple Langmuir probe
Authors: Kumar Ajai , Singh R. K. , Thomas Jinto , Sunil S.
Published: August 2009

The triple probe technique has been used to study the parameters of flowing plasma plume formed by laser-blow-off (LBO) of a multicomponent LiF–C target. The advantages of triple Langmuir probe over the single probe have been discussed with regard to the present study. Our results show that triple probe is better suited for parametric measurements close to the target. The spatiotemporal evolutions of electron density and temperature were measured in different ambient environments and for various laser fluences. The angular distribution of electron density and temperature was also measured. It was found that the presence of ambient gas drastically affects the electron density and temperature of the LBO plume. Large enhancement in ne and Te at intermediate pressures (10−2 Torr) is expected due to increase in collisional processes. On the other hand, laser fluence does not affect the observed ne and Te significantly. In vacuum, a new phenomenon, i.e., an oscillation in the trailing portion of the plasma plume at a closer distance from the target, is also reported.
Terahertz sensing with a carbon nanotube/two-dimensional electron gas hybrid transistor
Authors: Kawano Yukio , Uchida Takao , Ishibashi Koji
Published: August 2009

We report on a highly sensitive terahertz (THz) detector based on a carbon nanotube (CNT) transistor, which is integrated with a two-dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure. The operation principle of this device is that the CNT transistor senses electrical polarization induced by terahertz-excited electron-hole pairs in the 2DEG. The magnetic field dependence of the terahertz response signal (CNT current) is shown to follow features of cyclotron resonance of the 2DEG, indicating the validity of the above mechanism. The utilization of the present device structure and mechanism has enabled the detection of a small number of terahertz photons.
The study of surface Li–Sb alloy formation and electronic structure using photoelectron spectroscopy
Authors: Zhuang G. V. , Mun B. S. , Ross P. N.
Published: August 2009

The formation of surface Li–Sb alloy and its electronic structures are investigated with x-ray photoelectron spectroscopy (XPS). From the information on core-level shift of Sb 3d and Li 1s XPS spectra, the presence of charge transfer from Li to Sb is confirmed, while the chemical composition of formed alloy is estimated as Li3Sb. The density of states from valence band XPS shows a significant nonrigid part of band structures, suggesting strong covalent bonding between Li and Sb.
Spin-orbit engineering of semiconductor heterostructures: A spin-sensitive quantum-phase shifter
Authors: Nguyen T. L. Hoai , Drouhin Henri-Jean , Wegrowe Jean-Eric , Fishman Guy
Published: August 2009

In noncentrosymmetric semiconductors with zinc-blende structure grown along the [110] crystallographic direction, electrons with up- and down-spins undergo different quantum-phase shifts upon tunneling, which can be viewed as resulting from spin precession around a complex magnetic field. There is no spin filtering but a pure spin dephasing. The phase shift of the transmitted wave is proportional to the overall barrier-material thickness. We show that a device incorporating a number of resonant tunnel barriers constitutes an efficient quantum-phase shifter.
Soldered contact and current risetime effects on negative polarity wire array Z pinches
Authors: Chalenski D. A. , Kusse B. R. , Greenly J. B.
Published: August 2009

The experimental results described in this paper were motivated by earlier, low current, single wire experiments. In these experiments, single 10–25 μm diameter wires were driven by 1–5 kA current pulses with variable dI/dt from 5 to 60 A/ns. The amount of energy deposited in the wires, the expansion rate, and expansion uniformity that occurred before a plasma induced voltage collapse were found to depend on the polarity, dI/dt, and the quality of the contacts between the wires and the electrodes. This paper reports the results of experiments with cylindrical wire arrays driven by Cornell Beam Research Accelerator (COBRA) [J. B. Greenly, J. D. Douglas, D. A. Hammer et al., Rev. Sci. Instrum. 79, 073501 (2008)] current pulses that reached 1 MA. The pulse lengths were varied from 100 to 200 ns. These larger current pulses drove the wires of the array through the initiation phase studied in the single wire experiments and through ablation and Z-pinch implosion to stagnation on the cylindrical axis of the array. Regardless of the current pulse length, the COBRA dI/dt per wire during initiation reached approximately 175 A/ns and resistive voltage breakdown occurred at ∼13 ns. Wire-electrode contacts were modified by soldering the cathode ends of the wires to the brass electrode. With the 100 ns COBRA pulse, voltage monitor data suggested that soldering produced a smaller radius pinch, but bolometer data showed that this did not affect the total energy emitted from the array compared to nonsoldered contacts. With the 200 ns COBRA pulse and soldered contacts, the bolometer data showed an average of 69% increase in time integrated x-ray emission and the photoconducting detector data showed an increase in x-ray power and yield compared with nonsoldered contacts. Under these same conditions the four-frame extreme ultraviolet images showed a more pronounced “Christmas tree” effect at the cathode.
Electrostatic dampening dampens the anion propensity for the air-water interface
Authors: Wick Collin D.
Published: August 2009

Molecular dynamics simulations with polarizable potentials and electrostatic dampening were carried out to understand the influence of electrostatic dampening on the propensity of anions for the air-water interface. New anion molecular models incorporating these features were developed for this work. The results showed that electrostatic dampening reduced the average anion induced dipole in bulk water, in agreement with previous investigations [M. Masia, J. Chem. Phys. 128, 18 (2008)]. As a consequence, electrostatic dampening was found to significantly reduce, but not eliminate, the influence of polarizability on the anion propensity for the air-water interface. The Br− and I− models showed reduced propensity for the air-water interface with respect to previous models parametrized in a similar manner, but with no electrostatic dampening.
Three-dimensional micronanofabrication via two-photon-excited photoisomerization
Authors: Xia Hong , Zhang Wen-Yi , Wang Fang-Fang , Wu Dong , Liu Xiang-Wei , Chen Lei , Chen Qi-Dai , Ma Yu-Guang , Sun Hong-Bo
Published: August 2009

In this letter, laser micronanofabrication via two-photon absorption initiated isomerization was proposed and explored. Experimentally a cis-form rich poly[2,5-dihexyloxy-1,4-phenylene] vinylene)-alt-(2,5-diphenyl-1,4-phenylene vinylene)] (DPO-PPV) was used as the precursory material, which underwent pinpoint molecular conformational change upon the near-infrared femtosecond laser irradiation. Due to pronouncedly reduced solubility of trans-configuration molecules, the precipitate at the tiny volumes was implemented as voxels to construct two- and three-dimensional micronanostructures. This mechanism may provide an alternative enabling tool other than two-photon absorption initiated polymerization of resins for designable micronanofabrication of photonic or optoelectronic devices including organic electroluminescent devices, particularly those based on PPV and its derivatives.
The space-charge limiting current of a sheet relativistic electron beam in a rippled rectangular waveguide
Authors: Du Guang-Xing , Qian Bao-Liang
Published: August 2009

The expression of the space-charge limiting current of a sheet relativistic electron beam propagating in a rippled rectangular waveguide is derived. Using numerical computation, interesting results of the space-charge limiting current are provided. For the same sheet relativistic electron beam, the space-charge limiting current in a rippled rectangular waveguide with an average height of be and a ripple amplitude of h0 is less than that in a smooth-walled rectangular waveguide with a height of be−2h0, and larger than that in a smooth-walled rectangular waveguide of a height of be+2h0, and increases as the ripple period decreases. In addition, the larger the ripple amplitude of the rectangular waveguide is, the more rapidly the space-charge limiting current increases with the decrease in the ripple period. These results should be of interest to the area of propagation of intense sheet relativistic electron beam in a rippled rectangular waveguide for application of generating high-power microwaves.
A three-terminal spin-torque-driven magnetic switch
Authors: Sun J. Z. , Gaidis M. C. , O’Sullivan E. J. , Joseph E. A. , Hu G. , Abraham D. W. , Nowak J. J. , Trouilloud P. L. , Lu Yu , Brown S. L. , Worledge D. C. , Gallagher W. J.
Published: August 2009

A three-terminal spin-torque-driven magnetic switch is experimentally demonstrated. The device uses nonlocal spin current and spin accumulation as the main mechanism for current-driven magnetic switching. It separates the current-induced write operation from that of a magnetic tunnel junction based read. The write current only passes through metallic structures, improving device reliability. The device structure makes efficient use of lithography capabilities, important for robust process integration.
A method for nanofluidic device prototyping using elastomeric collapse
Authors: Park Seung-min , Huh Yun Suk , Craighead Harold G. , Erickson David
Published: August 2009

Nanofluidics represents a promising solution to problems in fields ranging from biomolecular analysis to optical property tuning. Recently a number of simple nanofluidic fabrication techniques have been introduced that exploit the deformability of elastomeric materials like polydimethylsiloxane (PDMS). These techniques are limited by the complexity of the devices that can be fabricated, which can only create straight or irregular channels normal to the direction of an applied strain. Here, we report a technique for nanofluidic fabrication based on the controlled collapse of microchannel structures. As is demonstrated, this method converts the easy to control vertical dimension of a PDMS mold to the lateral dimension of a nanochannel. We demonstrate here the creation of complex nanochannel structures as small as 60 nm and provide simple design rules for determining the conditions under which nanochannel formation will occur. The applicability of the technique to biomolecular analysis is demonstrated by showing DNA elongation in a nanochannel and a technique for optofluidic surface enhanced Raman detection of nucleic acids.
The BE06 Corpus of British English and recent language change
Authors: Baker Paul
Published: August 2009

This paper describes the BE06 Corpus, a one million word reference corpus of general written British English that was designed to be comparable to the Brown family of corpora. After providing a description of the Brown sampling frame, and giving the rationale for building a new corpus, the process of building the BE06 is elaborated upon, with reference to collecting previously published texts from internet sources, defining “British” authors and enabling accessibility of the corpus. Three studies of lexical frequency using BE06 and comparable corpora (LOB, FLOB and BLOB) are then carried out. These involve a comparison of the 20 most frequent lexical items, an examination of pronoun usage, and an investigation of keywords derived from comparing the 1991 FLOB corpus with the BE06. The paper ends with a critical evaluation of the worth of using the same sampling frame for linguistic studies of diachronic variation.
“I entirely understand” is a Blairism
Authors: Mollin Sandra
Published: August 2009

While the study of idiolect is a neglected area in corpus linguistics, the present article suggests that it can be fruitful. As a tool for studying an idiolect, the three-million-word Tony Blair Corpus is introduced. The maximiser collocations occurring in this corpus are compared to those in the BNC in order to identify those which are truly typical of the individual. A quantitative analysis involving three measures of collocational strength (normalised frequency, Mutual Information and log-likelihood) provide candidate collocations which strongly diverge in the two corpora. These are then subjected to tests of synonym preference and register specificity, resulting in a small number of collocations which can count as Blairisms.
A corpus-driven approach to formulaic language in English
Authors: Biber Douglas
Published: August 2009

The present study utilizes a corpus-driven approach to identify the most common multi-word patterns in conversation and academic writing, and to investigate the differing pattern types in the two registers. The paper first surveys the methodological characteristics of corpus-driven research and then contrasts the linguistic characteristics of two types of multi-word sequences: ‘multi-word lexical collocations’ (combinations of content words) versus ‘multi-word formulaic sequences’ (incorporating both function words and content words).  Building on this background, the primary focus of the paper is an empirical investigation of the ‘patterns’ represented by multi-word formulaic sequences. It turns out that the multi-word patterns typical of speech are fundamentally different from those typical of academic writing: patterns in conversation tend to be fixed sequences (including both function words and content words). In contrast, most patterns in academic writing are formulaic frames consisting of invariable function words with an intervening variable slot that is filled by content words.
Scrabble as a tool for Haitian Creole literacy
Authors: Hebblethwaite Benjamin
Published: August 2009

This paper argues that Scrabble can be used as a tool to help maintain and grow all levels of Haitian Creole literacy and it provides the technical details for developing the game. The rules of the English version are given to introduce the game’s basic structure. Haiti’s educational, sociolinguistic, and literacy conditions are presented in order to put in context the orthographic form proposed for the Haitian Creole version. An overview of game culture in Haiti shows Scrabble’s potential for success. Previous research on the adaptation of Scrabble into Latin by means of a quantitative corpus-linguistic method is examined. Difficult aspects of standard Haitian Creole orthography (IPN) are discussed in order to expose potential pitfalls in design. Quantitative analysis of a Haitian Creole textual corpus provides an empirical basis for the distribution of letter tiles and their point values. Problems encountered in test-games played by Haitian-American university students and Haitian elementary and high school students inform the final proposal. The paper examines the work necessary for the successful introduction of Haitian Creole Scrabble and it provides independent evidence of the game’s cognitive benefits. Haitian Creole Scrabble is argued to be a creative and special method for expanding and strengthening literacy in Haitian Creole and other creole languages.
Visual Crowding and the tone orthography of African languages
Authors: Roberts David
Published: August 2009

The effect of Crowding has long been recognised by cognitive psychologists engaged in examining the reading process. Yet it is not generally taken into account by most field linguists involved in the development of tone orthographies for emerging African languages. True, there is a general recognition that diacritic overload is unhelpful, but this has never been articulated with the help of the more precise terminology already on offer from the field of cognitive psychology. Using an experimental tone orthography developed for Kabiye (Gur, Togo) as an example, I postulate that an exhaustive representation of tone by means of accents will trigger Crowding. This is a hypothesis that has yet to be tested under clinical conditions. But the aim of this article is to call the phenomenon by its name for the first time and thereby stimulate further research. I also hope to demonstrate by means of this single example the gulf that exists between cognitive psychology and linguistics. Once we recognise that the gulf exists, we can begin to build bridges.
Attributable Mortality Rate for Carbapenem-Resistant Klebsiella pneumoniae Bacteremia
Authors: Borer Abraham , Saidel-Odes Lisa , Riesenberg Klaris , Eskira Seada , Peled Nejama , Nativ Ronit , Schlaeffer Francise , Sherf Michael
Published: August 2009

Objective.

To determine the attributable (direct) mortality and morbidity caused by carbapenem-resistant Klebsiella pneumoniae bacteremia.

Design.

A matched retrospective, historical cohort design, using a stepwise procedure to stringendy match the best control subjects to the best case subjects.

Setting.

A 1,000-bed tertiary-care university teaching hospital.

Patients.

Case subjects were defined as adult patients with carbapenem-resistant K. pneumoniae bacteremia during the period from October 2005 through October 2008. Control subjects were defined as patients who were very similar to case subjects except that they did not have bacteremia.

Methods.

Matching potential control subjects to case subjects was performed at a 1:1 ratio using a computerized record system. The criteria used included same hospitalization period, similar Charlson comorbidity index, same underlying disease, same age within 10 years, and same sex. Demographic and clinical characteristics were collected from medical records.

Results.

During the study period, 319 patients developed an infection due to carbapenem-resistant K. pneumoniae. Of these 319 patients, 39 (12.2%) developed a bloodstream infection, for an overall rate of 0.59 episodes of carbapenem-resistant K. pneumoniae bacteremia per 10,000 patient-days. We excluded 7 patients from our study, leaving a total of 32 case subjects in our cohort. Case subjects were significandy more likely than control subjects (n = 32) to require care in an intensive care unit (12 case subjects [37.5%] vs 3 control subjects [9.4%]), ventilator support (17 case subjects [53.1%] vs 8 control subjects [25%]), and use of a central venous catheter (19 case subjects [59.4%] vs 9 control subjects [28.1%]). For case subjects, the crude mortality rate was 71.9% (ie, 23 of the 32 case subjects died); for control subjects, the crude mortality rate was 21.9% (ie, 7 of the 32 control subjects died) (P < .001. For case subjects, the attributable mortality was 50% (95% confidence interval [CI], 15.3%-98.6%). A mortality risk ratio of 3.3 (95% CI, 2.9-28.5) was found for case subjects with carbapenem-resistant K. pneumoniae bacteremia.

Conclusions.

Patients with carbapenem-resistant K. pneumoniae require more intensive and invasive care. We have shown that the crude and attributable mortality rates associated with carbapenem-resistant K. pneumoniae bacteremia were striking.
Multisecant subspaces to smooth projective varieties in arbitrary characteristic
Authors: Noma Atsushi
Published: August 2009

Let

X
⊆

P

N

X \subseteq \mathbb {P}^{N}

be a projective variety of dimension

n
≥
1

n\geq 1

, degree

d
d

, and codimension

e
e

, not contained in any hyperplane, defined over an algebraically closed field

k
\Bbbk

of arbitrary characteristic. We show that if a

k
k

-dimensional linear subspace

M
M

meets

X
X

at the smooth locus such that

X
∩
M

X\cap M

is finite and locally lies on a smooth curve, then the length

l
(
X
∩
M
)

l(X\cap M)

does not exceed

d
−
e
+
k
−
min
{
g
,
e
−
k
}

d-e+k-\min \{g,e-k\}

for the sectional genus

g
g

of

X
X

.
Embedding 3-manifolds with circle actions
Authors: Hillman J.
Published: August 2009

Constraints on the Seifert invariants of orientable 3-manifolds

M
M

which admit fixed-point free

S
1

S^1

-actions and embed in

R

4

\mathbb {R}^4

are given. In particular, the generalized Euler invariant of the orbit fibration is determined up to sign by the base orbifold

B
B

unless

H
1

(
M
;

Z

)

H_1(M;\mathbb {Z})

is torsion free, in which case it can take at most one nonzero value (up to sign). An

H

2

×

E

1

\mathbb {H}^2\times \mathbb {E}^1

-manifold

M
M

with base orbifold

B
=

S
2

(

α
1

,
…
,

α
r

)

B=S^2(\alpha _1,\dots ,\alpha _r)

where all cone point orders are odd embeds in

R

4

\mathbb {R}^4

if and only if its Seifert data

S
S

is skew-symmetric.
On the syzygies of quasi-complete intersection space curves
Authors: Choi Youngook
Published: August 2009

In this paper, we discuss minimal free resolutions of the homogeneous ideals of quasi-complete intersection space curves. We show that if

X
X

is a quasi-complete intersection curve in

P

3

\mathbb P^3

, then

I
X

I_X

has a minimal free resolution
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="0 right-arrow circled-plus upper S left-parenthesis d Subscript i plus 3 Baseline plus c 1 right-parenthesis right-arrow circled-plus upper S left-parenthesis minus e Subscript i Baseline right-parenthesis right-arrow circled-plus upper S left-parenthesis minus d Subscript i Baseline right-parenthesis right-arrow upper I Subscript upper X Baseline right-arrow 0 comma">

0
→

⊕

i
=
1

μ
−
3

S
(

d

i
+
3

+

c
1

)
→

⊕

i
=
1

2
μ
−
4

S
(
−

e
i

)
→

⊕

i
=
1

μ

S
(
−

d
i

)
→

I
X

→
0
,

0\to \oplus _{i=1}^{\mu -3} S(d_{i+3}+c_1)\to \oplus _{i=1}^{2\mu -4}S(-e_i)\to \oplus _{i=1}^\mu S(-d_i)\to I_X\to 0,

\]
where

d
i

,

e
i

∈

Z

d_i,e_i\in \mathbb Z

and

c
1

=
−

d
1

−

d
2

−

d
3

c_1=-d_1-d_2-d_3

. Therefore the ranks of the first and the second syzygy modules are determined by the number of elements in a minimal generating set of

I
X

I_X

. Also we give a relation for the degrees of syzygy modules of

I
X

I_X

. Using this theorem, one can construct a smooth quasi-complete intersection curve

X
X

such that the number of minimal generators of

I
X

I_X

is

t
t

for any given positive integer

t
∈

Z

+

t\in \mathbb Z^+

.
Jet schemes of the commuting matrix pairs scheme
Authors: Sethuraman B. , Šivic Klemen
Published: August 2009

We show that for all

k
≥
1

k\ge 1

there exists an integer

N
(
k
)

N(k)

such that for all

n
≥
N
(
k
)

n\ge N(k)

the

k
k

-th order jet scheme over the commuting

n
×
n

n\times n

matrix pairs scheme is reducible.

At the other end of the spectrum, it is known that for all

k
≥
1

k\ge 1

the

k
k

-th order jet scheme over the commuting

2
×
2

2\times 2

matrices is irreducible; we show that the same holds for

n
=
3

n=3

.
The Function of the Intermediate Compartment in Pre-Golgi Trafficking Involves its Stable Connection with the Centrosome
Authors: Marie Michaël , Dale Hege A. , Sannerud Ragna , Saraste Jaakko
Published: August 2009

Because the functional borders of the intermediate compartment (IC) are not well defined, the spatial map of the transport machineries operating between the endoplasmic reticulum (ER) and the Golgi apparatus remains incomplete. Our previous studies showed that the IC consists of interconnected vacuolar and tubular parts with specific roles in pre-Golgi trafficking. Here, using live cell imaging, we demonstrate that the tubules containing the GTPase Rab1A create a long-lived membrane compartment around the centrosome. Separation of this pericentrosomal domain of the IC from the Golgi ribbon, due to centrosome motility, revealed that it contains a distinct pool of COPI coats and acts as a temperature-sensitive way station in post-ER trafficking. However, unlike the Golgi, the pericentrosomal IC resists the disassembly of COPI coats by brefeldin A, maintaining its juxtaposition with the endocytic recycling compartment, and operation as the focal point of a dynamic tubular network that extends to the cell periphery. These results provide novel insight into the compartmental organization of the secretory pathway and Golgi biogenesis. Moreover, they reveal a direct functional connection between the IC and the endosomal system, which evidently contributes to unconventional transport of the cystic fibrosis transmembrane conductance regulator to the cell surface.
ERNEST: a toolbox for chemical reaction network theory
Authors: Soranzo Nicola , Altafini Claudio
Published: August 2009

Summary: ERNEST Reaction Network Equilibria Study Toolbox is a MATLAB package which, by checking various different criteria on the structure of a chemical reaction network, can exclude the multistationarity of the corresponding reaction system. The results obtained are independent of the rate constants of the reactions, and can be used for model discrimination.

Availability and Implementation: The software, implemented in MATLAB, is available under the GNU GPL free software license from http://people.sissa.it/∼altafini/papers/SoAl09/. It requires the MATLAB Optimization Toolbox.

Contact:  altafini@sissa.it