bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of American English on second generation Lao immigrant speakers
Authors: Chanethom Vincent
Published: August 2010

For many centuries, the United States has opened its doors to a variety of immigrants throughout the globe, engendering situations that Fishman (2004: 406) characterizes as ‘pluralistic societal impact.’ Upon coming to America, twentieth century immigrants found themselves immersed in a context in which not only their cultures clashed with that of the U.S., but also their mother tongues interacted with American English. The language patterns resulting from such interactions between immigrants' native languages and American English has been of great interest to the linguistic research community for the past several decades. For instance, research in the field of language contact has been particularly marked by the influential work undertaken by Thomason and Kaufman (1988) in which they developed a model to predict the nature of these contact-induced changes and to examine the mechanism by which these changes emerge.
ESTIMATION OF NONLINEAR ERROR CORRECTION MODELS
Authors: Hwan Seo Myung
Published: August 2010

Asymptotic theory for the estimation of nonlinear vector error correction models that exhibit regime-specific short-run dynamics is developed. In particular, regimes are determined by the error correction term, and the transition between regimes is allowed to be discontinuous, as in, e.g., threshold cointegration. Several nonregular problems are resolved. First of all, consistency—square rootnconsistency for the cointegrating vectorβ—is established for the least squares estimation of this general class of models. Second, the convergence rates are obtained for the least squares of threshold cointegration, which aren3/2andnforβandγ, respectively, whereγdenotes the threshold parameter. This fast rate forβin itself is of practical relevance because, unlike in smooth transition models, the estimation error inβdoes not affect the estimation of short-run parameters. We also derive asymptotic distributions for the smoothed least squares estimation of threshold cointegration.
PIVOTAL STRUCTURAL CHANGE TESTS IN LINEAR SIMULTANEOUS EQUATIONS WITH WEAK IDENTIFICATION
Authors: Caner Mehmet
Published: August 2010

Asymptotically pivotal structural change tests are developed for simultaneous equations with weakly identified parameters, extending the boundedly pivotal tests of Caner (2007, Journal of Econometrics 137, 28–67) by means of a simple reparametrization of the model.
BEFORE DEVELOPMENT ECONOMICS: WESTERN POLITICAL ECONOMY, THE “RUSSIAN CASE,” AND THE FIRST PERCEPTIONS OF ECONOMIC BACKWARDNESS (FROM THE 1760S UNTIL THE MID-NINETEENTH CENTURY)
Authors: ADAMOVSKY EZEQUIEL
Published: August 2010

Before the emergence of the field of development economics in the mid-1940s, the mainstream of Western economists had very little to say about the world outside western Europe. However, perhaps due to Russia’s ambivalent location as a nation considered not fully European (nor completely Asiatic) and to her status as a major player in the international arena despite the fact of her modest economic achievements, from the eighteenth century onwards the “Russian case” called the attention of some of the most prominent Western minds, including the first economists. By discussing Russia’s economy, they came to notions and concepts regarding development and backwardness that, to a great extent. informed the twentieth-century debate. The aim of this article is to explore the way in which Russia as a case study affected the evolution of ideas on economic growth or development. The evidence of things Russian, it will be argued, raised doubts about common economic views, thus enabling new thinking that pointed either to criticism of liberal orthodoxy, or to expansion and refinement of its arguments.
HOW “CHICAGOAN” ARE GARY BECKER’S ECONOMIC MODELS OF MARRIAGE?
Authors: GROSSBARD SHOSHANA
Published: August 2010

This paper describes Gary Becker’s theoretical models of marriage. At the micro level, these are all rational choice models. At the market level, Becker offers two major types of models: partial equilibrium models based on price theory as taught by Marshall and Friedman; and optimal sorting models based on optimal assignment models. This paper examines some of the possible intellectual influences on Becker’s theory of marriage, compares Becker’s research on marriage with that of some scholars interested in intra-marriage distribution, and documents that Becker’s students at Chicago were more interested in Becker’s Friedmanian models of marriage than in his optimal assignment models.
Conceptual issues in institutional economics: clarifying the fluidity of rules
Authors: MORGAN JAMIE , OLSEN WENDY
Published: August 2010

This paper addresses the issue of how rules are conceptualized by Hodgson in Old Institutional Economics (OIE). The argument is put forward that the concept of rules can be constructively clarified. Rather than provide a general form of single rules within a rule system, we argue for a taxonomic range of single rule forms. This approach has the additional advantage of providing a more explicit account of how rules operate as part of a rule system. It also provides one way to address the fluidity of rules. Rules are understood to be more or less fluid (incomplete) and subject to a practical dynamism. This, we argue, can be differentiated from the idea of tendency based on the capacity of agents not to follow rules. A useful concept here is that of ‘mezzo rules’ or recodifications that both define the rule and distance the agent from their own rule-following behaviour. In pursuing the argument we also highlight various methodological implications. First, conceptual development is a key aspect of the OIE, particularly when it is located within Dow's structured pluralism. As such elaboration on rule forms enhances the consistency of OIE as methodology. Second, the exploration of a taxonomic range of rules and of forms of fluidity can provide useful resources in mapping out institutional processes in real research.
Effect of Some Natural Mineral Waters in Nutrient Uptake by Caco-2 Cells
Authors: Gonçalves Pedro , Araújo João R. , Martel Fátima
Published: August 2010

We studied the effect of some mineral waters and some of their constituents on the apical uptake of 14C-butyrate (14C-BT) and 3H-O-methyl-D-glucose (3H-OMG) by Caco-2 cells. Uptake of 14C-BT increased after a 20-minute exposure to 1 % (v/v) distilled water, and, compared to distilled water, it was decreased by Pedras Salgadas® 1 % (v/v) and Melgaço® 5 % (v/v), and increased by Vidago® 5 % (v/v). Moreover, it increased after a 48-hour exposure to Vidago® or Melgaço® waters (5 % (v/v)). Also, uptake of 14C-BT was reduced after a 20-minute exposure to MgCl2, MgSO4, or CaCl2. Uptake of 3H-OMG was reduced after a 20-minute exposure to Melgaço® water [1 % (v/v)], when compared to distilled water. Also, a 48-hour exposure to Pedras Salgadas® or Melgaço® water (5 % (v/v)) increased and decreased uptake, respectively. Finally, uptake of 3H-OMG decreased after a 20-minute exposure to MgSO4 or NaF. In conclusion, uptake of 14C-BT and 3H-OMG by Caco-2 cells is differently modulated by distinct mineral waters.
Z mode waves as the source of Saturn narrowband radio emissions
Authors: Ye Sheng‐Yi , Menietti J. D. , Fischer G. , Wang Z. , Cecconi B. , Gurnett D. A. , Kurth W. S.
Published: August 2010

We report 5 kHz narrowband Z mode emissions observed by the Cassini Radio and Plasma Waves Science (RPWS) instrument during high latitude perikrone passes. The narrowband emissions observed below the local electron cyclotron frequency (fce) are >20 dB more intense than the usual L‐O mode narrowband emissions observed above local fce. Polarization measurements show that the narrowband emissions observed below fce are oppositely polarized to those above fce, which identifies the emissions below fce with Z mode. We propose that the L‐O mode narrowband emissions observed at 5 kHz are mode converted from the Z mode waves at a density gradient or density irregularity. The Z mode to L‐O mode conversion via scattering off of density irregularities can also account for the direction finding results of 5 kHz narrowband emissions which point to a source in the auroral zone. We also present the first magnetic field measurements of Saturn narrowband emissions validating their electromagnetic nature.
Relative impact of windblown dust versus anthropogenic fugitive dust in PM2.5 on air quality in North America
Authors: Park S. H. , Gong S. L. , Gong W. , Makar P. A. , Moran M. D. , Zhang J. , Stroud C. A.
Published: August 2010

A new windblown dust emissions module was recently implemented into A Unified Regional Air Quality Modeling System (AURAMS), a Canadian regional air quality model, to investigate the relative impact of windblown dust versus anthropogenic fugitive dust on air quality in North America. In order to apply the windblown dust emissions module to the entire North American continent, a soil grain size distribution map was developed using the outputs of 4 monthly runs of AURAMS for 2002 and available PM2.5 dust content observations. The simulation results using the new soil grain size distribution map showed that inclusion of windblown dust emissions is essential to predict the impact of dust aerosols on air quality in North America, especially in the western United States. The windblown dust emissions varied widely by season, whereas the anthropogenic fugitive dust emissions did not change significantly. In the spring (April), the continental monthly average emissions rate of windblown dust (4.1 × 107 kg/d) was much higher than that of anthropogenic fugitive dust (1.5 × 107 kg/d). The total amount of windblown dust emissions in North America predicted by the model for 2002 was comparable to that of anthropogenic fugitive dust emissions. Even with the inclusion of windblown dust emissions, however, the model still had difficulty simulating dust concentrations. Further improvements are needed, in terms of both limitations of the windblown dust emission module and uncertainties in the anthropogenic fugitive dust emissions inventories, for improved dust modeling.
Characterization of NOx, SO2, ethene, and propene from industrial emission sources in Houston, Texas
Authors: Washenfelder R. A. , Trainer M. , Frost G. J. , Ryerson T. B. , Atlas E. L. , de Gouw J. A. , Flocke F. M. , Fried A. , Holloway J. S. , Parrish D. D. , Peischl J. , Richter D. , Schauffler S. M. , Walega J. G. , Warneke C. , Weibring P. , Zheng W.
Published: August 2010

The Houston‐Galveston‐Brazoria urban area contains industrial petrochemical sources that emit volatile organic compounds and nitrogen oxides, resulting in rapid and efficient ozone production downwind. During September to October 2006, the NOAA WP‐3D aircraft conducted research flights as part of the second Texas Air Quality Study (TexAQS II). We use measurements of NOx, SO2, and speciated hydrocarbons from industrial sources in Houston to derive source emission ratios and compare these to emission inventories and the first Texas Air Quality Study (TexAQS) in 2000. Between 2000 and 2006, NOx/CO2 emission ratios changed by an average of −29% ± 20%, while a significant trend in SO2/CO2 emission ratios was not observed. We find that high hydrocarbon emissions are routine for the isolated petrochemical facilities. Ethene (C2H4) and propene (C3H6) are the major contributors to ozone formation based on calculations of OH reactivity for organic species including C2–C10 alkanes, C2–C5 alkenes, ethyne, and C2–C5 aldehydes and ketones. Measured ratios of C2H4/NOx and C3H6/NOx exceed emission inventory values by factors of 1.4–20 and 1–24, respectively. We examine trends in C2H4/NOx and C3H6/NOx ratios between 2000 and 2006 for the isolated petrochemical sources and estimate a change of −30% ± 30%, with significant day‐to‐day and within‐plume variability. Median ambient mixing ratios of ethene and propene in Houston show decreases of −52% and −48%, respectively, between 2000 and 2006. The formaldehyde, acetaldehyde, and peroxyacetyl nitrate products produced by alkene oxidation are observed downwind, and their time evolution is consistent with the rapid photochemistry that also produces ozone.
Dune field pattern formation and recent transporting winds in the Olympia Undae Dune Field, north polar region of Mars
Authors: Ewing Ryan C. , Peyret Aymeric‐Pierre B. , Kocurek Gary , Bourke Mary
Published: August 2010

High‐Resolution Imaging Science Experiment (HiRISE) imagery of the central Olympia Undae Dune Field in the north polar region of Mars shows a reticulate dune pattern consisting of two sets of nearly orthogonal dune crestlines, with apparent slipfaces on the primary crests, ubiquitous wind ripples, areas of coarse‐grained wind ripples, and deflated interdune areas. Geomorphic evidence and dune field pattern analysis of dune crest length, spacing, defect density, and orientation indicates that the pattern is complex, representing two constructional generations of dunes. The oldest and best‐organized generation forms the primary crestlines and is transverse to circumpolar easterly winds. Gross bed form‐normal analysis of the younger pattern of crestlines indicates that it emerged with both circumpolar easterly winds and NE winds and is reworking the older pattern. Mapping of secondary flow fields over the dunes indicates that the most recent transporting winds were from the NE. The younger pattern appears to represent an influx of sediment to the dune field associated with the development of the Olympia Cavi reentrant, with NE katabatic winds channeling through the reentrant. A model of the pattern reformation based upon the reconstructed primary winds and resulting secondary flow fields shows that the development of the secondary pattern is controlled by the boundary condition of the older dune topography.
Controls on the production of organohalogens by phytoplankton: Effect of nitrate concentration and grazing
Authors: Smythe‐Wright Denise , Peckett Cristina , Boswell Stephen , Harrison Rebecca
Published: August 2010

Using a number of laboratory culture experiments we have been able to show that trace gas release by phytoplankton is affected by changes in ambient nitrate conditions. Nutrient concentrations are fundamentally important to phytoplankton community structure and primary production, so it is important to understand if changes in nitrate levels are likely to affect metabolic processes. Recent human activities have added a large quantity of atmospheric nitrogen to the open ocean and this, in turn, will affect both carbon dioxide drawdown and nitrous oxide release. In contrast, ocean prediction models tell us that large parts of the ocean are going to become more oligotrophic. How these changes will affect other climatically active gases, e.g., organohalogens, is unclear. In this study we look at the effect of varying the nitrate to phosphate ratio on the release of three methyl halides. Some attention is also given to the effects of grazing as a means of gas release. Assuming that a 16:1 nitrate:phosphate ratio is the norm, we show that increasing the nitrate level above 16 μmol L−1 can lead to up to an 85% increase in trace gas production per unit cell while lowering the concentration can result in up to a 65% reduction. This is the first time that such a nutrient effect has been observed. Grazing by the microzooplankton Oxyrrhis marina also increases release, but whether this is due to enhanced metabolic processes caused by stress or the breaking down of cells due to grazing is unclear.
Midnight density and temperature maxima, and thermospheric dynamics in Whole Atmosphere Model simulations
Authors: Akmaev R. A. , Wu F. , Fuller‐Rowell T. J. , Wang H. , Iredell M. D.
Published: August 2010

Hydrostatic expansion in a gravity field of an atmospheric layer with elevated temperatures, such as the long known thermospheric midnight temperature maximum (MTM), results in a total mass density increase at a given altitude above the layer. Long‐term simulations with the Whole Atmosphere Model reveal a noticeable midnight density maximum (MDM), appropriately lagging behind the MTM at the same height. The MDM magnitude, timing, and variability are in good agreement with available in‐situ observations. Of particular importance is the observation of a downward phase progression of the MDM peak time obtained from the San Marco satellites and closely reproduced in the model results. This is consistent with the suggestion, made over 30 years ago, that both the MTM and MDM are driven by tidal waves, in particular, the terdiurnal tide propagating upward from the lower atmosphere and interacting with a diurnally varying ion drag. The accompanying wind variations are also found in good agreement with radar observations, which first related them to the nighttime ionosphere collapse in the early 1970s.
An optimal fitting approach to improve the GISS ModelE aerosol optical property parameterization using AERONET data
Authors: Li Jing , Liu Li , Lacis Andrew A. , Carlson Barbara E.
Published: August 2010

We improve the updated 2000 Goddard Institute for Space Studies, New York, ModelE aerosol optical property parameterization using an optimal fitting approach with AERONET ground measurements. The model aerosol optical properties, such as optical depth, are calculated using the aerosol mass density field from a chemical transport model, Mie scattering parameters, a prescribed dry size for each aerosol species assuming external mixing, and a hygroscopicity parameterization. A comparison between the model‐ and AERONET‐measured optical depth (AOD) and Ångström exponent (AE) indicates that the general circulation model (GCM) aerosol parameterization has a flatter AOD spectral dependence, thus a very low biased AE, which suggests that the aerosol sizes used in the model are too large. The seasonal variation of GCM AE also disagrees with that of AERONET data. On the basis of these results, we identify GCM aerosol size as the most poorly constrained parameter and develop an optimal fitting technique to adjust the GCM aerosol dry size by minimizing the total mean square error between the GCM and AERONET AOD at the six AERONET wavelengths. After adjusting the aerosol's dry size, the agreement between the GCM AE with AERONET data is improved. The fitted AOD at the six wavelengths closely matches AERONET data over most biomass burning, dust, and rural regions. The results are also greatly improved for the other aerosol types. The global distribution of the optimally fitted sizes displays regionally uniform characteristics, which allows the generation of a geographically varying size data set. Model uncertainty caused by other factors is also represented by an uncertainty parameter, which is mainly attributed to errors from aerosol mass concentration, Mie scattering parameters, relative humidity, and AERONET measurements. The relative contribution of each of these errors sources depends on the relevant aerosol type. Further comparison between the absorption optical depth and AE spectral dependence provides additional information on absorbing aerosols and GCM fine‐to‐coarse mode ratio, which will be addressed in future research.
Compound Energy Systems
Authors: Obara Shin'ya , Hepbasli Arif
Published: August 2010

This book, a distillation of information only touched upon in other books, is aimed at undergraduate and postgraduate students, scientists, engineers and industrialists with an interest in the field.
Background
Authors: Obara Shin’ya
Published: August 2010

The distributed energy system using renewable energy is expected as an energy supply system with low environmental impact. In order to make utilization of renewable energy increase, we should develop energy storage equipment and the operation optimization technique of the compound energy system. This technique is related with a microgrid or a smartgrid. In this chapter, the contents of each chapter are introduced briefly. Furthermore, the compound energy system described in this book is introduced.
Operation of Compound Energy System – Fuel Cell Network System Considering Reduction in Fuel Cell Capacity
Authors: Obara Shin'ya
Published: August 2010

Reduction in fuel cell capacity linked to a fuel cell network system is considered. When the power demand of the whole network is small, some of the electric power generated by the fuel cell is supplied to a water electrolysis device, and hydrogen and oxygen gases are generated. Both gases are compressed with each compressor and they are stored in cylinders. When the electric demand of the whole network is large, both gases are supplied to the network, and fuel cells are operated by these hydrogen and oxygen gases. Furthermore, an optimization plan is made to minimize the quantity of heat release of the hot water piping that connects each building. Such an energy network is analyzed assuming connection of individual houses, a hospital, a hotel, a convenience store, an office building, and a factory.
PEFC/Engine Generator Compound Energy System (1) – CO2 Discharge Characteristic of PEFC/Hydrogen-Gas-Engine Hybrid Cogeneration
Authors: Obara Shin’ya
Published: August 2010

When introducing fuel cell cogeneration into an apartment house, operations in a low-load region that accord with load fluctuation occur frequently. Therefore, in order to keep energy costs low, it is necessary to introduce a method of improving power generation efficiency at the time of low load. Thus, in this Chapter, the hybrid cogeneration system (HCGS) that uses a hydrogen gas engine (NEG) and proton exchange membrane fuel cell (PEFC) together is proposed. In the gas engine, when hydrogen concentration is increased at the time of low load, the improvement of an exhaust cleanup and brake thermal efficiency is confirmed. In this Chapter, the capacity of fuel consumption and carbon dioxide emissions are investigated by numerical analysis regarding the introduction of HCGS into apartment houses in Sapporo in Japan. It is thought that fuel consumption conditions with little heat demand and the power generation efficiency of HCGS are more advantageous.
Performance Analysis and Assessment of Compound Energy Systems Using Exergy Analysis Method
Authors: Hepbasli Arif
Published: August 2010

Exergy is a way to a sustainable development, while exergy analysis method is a very useful tool, which has recently gained a big importance in the design, analysis, simulation and performance evaluation of various energy systems. In this section, exergetic performance evaluation of two types of compound energy systems is made based on the actual operational data. The fist one is a solar assisted domestic hot water (DHW) tank integrated ground source heat pump (GSHP) system, while the second one is a high-temperature electrolysis (HTE) process coupled with a geothermal source. In the analysis, three balance (mass, energy and exergy) equations are applied to the two systems considered for modeling purposes. Exergy (second law) efficiency values for both systems are given, while exergy destructions in each of the system components are determined to assess their individual performances by presenting the potential for improvements. It may be concluded that the exergetic evaluation method presented here may be applied to other compound energy systems as a useful tool.
Alfven soliton and multisoliton dynamics perturbed by nonlinear Landau damping
Authors: Sánchez-Arriaga G.
Published: August 2010

The evolution of weakly dispersive nonlinear Alfven waves propagating either parallel or oblique to the ambient magnetic field is investigated through the derivative nonlinear Schrödinger equation (DNLS) perturbed by nonlinear Landau damping. The dynamics is analyzed with the aid of a numeric algorithm based on the inverse scattering transform (IST) and an adiabatic model that takes advantages of the perturbed DNLS invariants. Both techniques are applied to five types of DNLS soliton and multisoliton solutions: (i) the parallel Alfven soliton, (ii) the bright and dark one-parameter oblique, (iii) the breather two-parameter oblique, (iv) two parallel Alfven solitons, and (v) the combination of a dark and a bright oblique solitons. For the parallel solitons, the adiabatic model describes correctly the dynamics and it also recovers the well-known result given by the perturbed IST. Due to the radiation emission and the formation of dark solitons, the behavior of oblique solitons is more complicated and multisoliton solutions are required in the adiabatic model. The analysis shows that parallel solitons develop into the normal regime, whereas the oblique waves leads to the formation of dark solitons and breathers with a wavepacket form.
A kinetic Ising model study of dynamical correlations in confined fluids: Emergence of both fast and slow time scales
Authors: Biswas Rajib , Bagchi Biman
Published: August 2010

Experiments and computer simulation studies have revealed existence of rich dynamics in the orientational relaxation of molecules in confined systems such as water in reverse micelles, cyclodextrin cavities, and nanotubes. Here we introduce a novel finite length one dimensional Ising model to investigate the propagation and the annihilation of dynamical correlations in finite systems and to understand the intriguing shortening of the orientational relaxation time that has been reported for small sized reverse micelles. In our finite sized model, the two spins at the two end cells are oriented in the opposite directions to mimic the effects of surface that in real system fixes water orientation in the opposite directions. This produces opposite polarizations to propagate inside from the surface and to produce bulklike condition at the center. This model can be solved analytically for short chains. For long chains, we solve the model numerically with Glauber spin flip dynamics (and also with Metropolis single-spin flip Monte Carlo algorithm). We show that model nicely reproduces many of the features observed in experiments. Due to the destructive interference among correlations that propagate from the surface to the core, one of the rotational relaxation time components decays faster than the bulk. In general, the relaxation of spins is nonexponential due to the interplay between various interactions. In the limit of strong coupling between the spins or in the limit of low temperature, the nature of relaxation of the spins undergoes a qualitative change with the emergence of a homogeneous dynamics where decay is predominantly exponential, again in agreement with experiments.
Low Reynolds number effects on rotating turbulent Poiseuille flow
Authors: Iida O. , Fukudome K. , Iwata T. , Nagano Y.
Published: August 2010

Direct numerical simulations with a spectral method are performed to study the effects of spanwise rotation on a turbulent Poiseuille flow at very low Reynolds number. At this Reynolds number, the region of zero absolute vorticity, typically observed in the mean velocity profile of rotating Poiseuille flow, disappears in the channel center, and the mean velocity gradient becomes opposite to that of zero absolute vorticity. When zero absolute vorticity disappears, very long low-speed streaks, accompanied by the vortices aligned in the streamwise direction like a chain, dominate the flow, in which the transfer of turbulent kinetic energy into the vicinity of the wall and small-scale streamwise vortices disappear there. However, low-speed fluids are pumped up from the near-wall region, and trapped into the channel center by the larger-scale chain vortices away from the wall, which decreases the mean velocity in the channel center and shifts its peak location toward the wall.
Effective design of multiple hollow cathode electrode to enhance the density of rf capacitively coupled plasma
Authors: Lee H. S. , Lee Y. S. , Seo S. H. , Chang H. Y.
Published: August 2010

Multiple-hole electrode rf capacitively coupled plasma is experimentally studied to determine the optimum condition for high-density plasma discharge. The plasma density was measured at various pressures, hole diameters, rf currents, and gas species conditions. The bulk plasma intrusion in the hole and the ionization avalanche in the sheath region facilitated high-density plasma generation when the diameter of the hole is slightly wider than triple the sheath length. The analytic design of the efficient multihole electrode for high-density rf capacitively coupled plasma discharge will be discussed.
Electroluminescence from ZnO nanoflowers/GaN thin film p-n heterojunction
Authors: Ahn Jaehui , Mastro Michael A. , Hite Jennifer , Eddy Charles R. , Kim Jihyun
Published: August 2010

Dielectrophoretic force was employed to position ZnO nanoflowers on a p-type GaN thin film prepatterned with Ti/Al/Ni/Au n-type and Ni/Au p-type contact metallizations. Analytical and finite element calculations were employed to determine the optimal alternating current frequency to attract the randomly dispersed ZnO nanoflowers to the n-type contact located on but isolated from the p-GaN thin film. The n-type ZnO nanoflower/p-type GaN thin film heterojunction displayed rectifying current-voltage behavior characteristic of a pristine p-n junction diode and emitted violet light under forward bias above 4.7–5.5 V.
Colossal optical activity of split-ring resonator arrays for millimeter waves
Authors: Engelbrecht S. , Wunderlich M. , Shuvaev A. M. , Pimenov A.
Published: August 2010

We have studied the optical activity of bilayered split-ring resonator arrays for millimeter waves. Using quasi-optical technique within controlled polarization rotation we were able to measure transmission and phase shift of these arrays within geometries with parallel and crossed polarizers. We determined experimentally the complex 2×2 transmission matrix which fully characterizes the arrays. We obtain an optical rotation of up to 600 deg/λ for the array thickness of 90 μm and at 3 mm wavelength. The polarization dependence of the optical activity can be effectively suppressed by introducing higher symmetries in the structures. Our results demonstrate the possibility to effectively control and investigate the polarization state of millimeter wave radiation.
Density of trap states measured by photon probe into ZnO based thin-film transistors
Authors: Lee Kimoon , Ko Gunwoo , Lee Gun Hwan , Han Gi bok , Sung Myung M. , Ha Tae Woo , Kim Jae Hoon , Im Seongil
Published: August 2010

We report on photo-excited trap-charge-collection spectroscopy, contrived to measure the density of deep-level traps near channel/dielectric interface in a working ZnO based thin-film transistor as a function of photon probe energy. Free charges trapped at a certain energy level are liberated by the correspondingly energetic photons and then electrically collected at the source/drain electrodes. During this photo-electric process, the threshold voltage of TFT shifts and its magnitude provides the density-of-state information of charge traps. In the present work, we directly characterized the density-of-state of ZnO based thin-film transistors with polymer-oxide double dielectrics after evaluating their gate stabilities.
Inherited sperm head abnormalities in the B10.M mouse strain
Authors: Gotoh Hideo
Published: August 2010

Examination of sperm head morphology is one of the requisite tests of the functional capacity of semen in reproduction. In the present study, genetic effects on morphological sperm head abnormalities in mice were investigated. The frequency of abnormal spermatozoa was determined in 17 inbred mouse strains and it was found that strain B10.M had the highest frequency of abnormal spermatozoa (44.7%). Segregation analysis was then used to show that the abnormal sperm phenotype in B10.M mice was inherited. The results indicated that this sperm abnormality was controlled by two distinct recessive alleles. It is proposed that the high frequency of the heritable abnormal sperm phenotype in the mouse B10.M strain explains the subfertility of this strain, as evidenced by its reduced litter size.
Nanopore DNA sequencing with MspA
Authors: Derrington Ian M. , Butler Tom Z. , Collins Marcus D. , Manrao Elizabeth , Pavlenok Mikhail , Niederweis Michael , Gundlach Jens H.
Published: August 2010

Nanopore sequencing has the potential to become a direct, fast, and inexpensive DNA sequencing technology. The simplest form of nanopore DNA sequencing utilizes the hypothesis that individual nucleotides of single-stranded DNA passing through a nanopore will uniquely modulate an ionic current flowing through the pore, allowing the record of the current to yield the DNA sequence. We demonstrate that the ionic current through the engineered
Mycobacterium smegmatis
porin A, MspA, has the ability to distinguish all four DNA nucleotides and resolve single-nucleotides in single-stranded DNA when double-stranded DNA temporarily holds the nucleotides in the pore constriction. Passing DNA with a series of double-stranded sections through MspA provides proof of principle of a simple DNA sequencing method using a nanopore. These findings highlight the importance of MspA in the future of nanopore sequencing.
Charges in the hydrophobic interior of proteins
Authors: Isom Daniel G. , Castañeda Carlos A. , Cannon Brian R. , Velu Priya D. , García-Moreno E. Bertrand
Published: August 2010

Charges are inherently incompatible with hydrophobic environments. Presumably for this reason, ionizable residues are usually excluded from the hydrophobic interior of proteins and are found instead at the surface, where they can interact with bulk water. Paradoxically, ionizable groups buried in the hydrophobic interior of proteins play essential roles, especially in biological energy transduction. To examine the unusual properties of internal ionizable groups we measured the p
K
a
of glutamic acid residues at 25 internal positions in a stable form of staphylococcal nuclease. Two of 25 Glu residues titrated with normal p
K
a
near 4.5; the other 23 titrated with elevated p
K
a
values ranging from 5.2–9.4, with an average value of 7.7. Trp fluorescence and far-UV circular dichroism were used to monitor the effects of internal charges on conformation. These data demonstrate that although charges buried in proteins are indeed destabilizing, charged side chains can be buried readily in the hydrophobic core of stable proteins without the need for specialized structural adaptations to stabilize them, and without inducing any major conformational reorganization. The apparent dielectric effect experienced by the internal charges is considerably higher than the low dielectric constants of hydrophobic matter used to represent the protein interior in electrostatic continuum models of proteins. The high thermodynamic stability required for proteins to withstand the presence of buried charges suggests a pathway for the evolution of enzymes, and it underscores the need to mind thermodynamic stability in any strategy for engineering novel or altered enzymatic active sites in proteins.
BK channels play a counter-adaptive role in drug tolerance and dependence
Authors: Ghezzi Alfredo , Pohl Jascha B. , Wang Yan , Atkinson Nigel S.
Published: August 2010

Disturbance of neural activity by sedative drugs has been proposed to trigger a homeostatic response that resists unfavorable changes in net cellular excitability, leading to tolerance and dependence. The
Drosophila slo
gene encodes a BK-type Ca
2+
-activated K
+
channel implicated in functional tolerance to alcohol and volatile anesthetics. We hypothesized that increased expression of BK channels induced by these drugs constitutes the homeostatic adaptation conferring resistance to sedative drugs. In contrast to the dogmatic view that BK channels act as neural depressants, we show that drug-induced
slo
expression enhances excitability by reducing the neuronal refractory period. Although this neuroadaptation directly counters some effects of anesthetics, it also causes long-lasting enhancement of seizure susceptibility, a common symptom of drug withdrawal. These data provide a possible mechanism for the long-standing counter-adaptive theory for drug tolerance in which homeostatic adaptations triggered by drug exposure to produce drug tolerance become counter-adaptive after drug clearance and result in symptoms of dependence.
G-quadruplex structures in RNA stimulate mitochondrial transcription termination and primer formation
Authors: Wanrooij Paulina H. , Uhler Jay P. , Simonsson Tomas , Falkenberg Maria , Gustafsson Claes M.
Published: August 2010

The human mitochondrial transcription machinery generates the primers required for initiation of leading-strand DNA replication. According to one model, the 3′ end of the primer is defined by transcription termination at conserved sequence block II (CSB II) in the mitochondrial DNA control region. We here demonstrate that this site-specific termination event is caused by G-quadruplex structures formed in nascent RNA upon transcription of CSB II. We also demonstrate that a poly-dT stretch downstream of CSB II has a modest stimulatory effect on the termination efficiency. The mechanism is reminiscent of Rho-independent transcription termination in prokaryotes, with the exception that a G-quadruplex structure replaces the hairpin loop formed in bacterial mRNA during transcription of terminator sequences.
Another Look at Pesticide Productivity and Pest Damage
Authors: Chambers Robert G. , Karagiannis Giannis , Tzouvelekas Vangelis
Published: August 2010

Using the Lichtenberg‐Zilberman‐Fox‐Weersink damage specification, we develop a short‐run, supply‐response framework based on rational producer behavior in the presence of damage agents. We show how representation can be used to measure and decompose the economic damage associated with the presence of pests, how to measure the shadow prices of damage‐control agents, how to measure the manner in which pesticide application biases variable input use, and how pesticide application affects the relative returns to quasi‐fixed factors of production. An econometric version of the model is estimated using a panel data set on Greek olive producers. Both our theoretical and our empirical results suggest that the most traditional measure of pest damage understates actual economic losses and revenue losses due to pests.
Measuring the physical cohesiveness of proteins using physical interaction enrichment
Authors: Sama Iziah Edwin , Huynen Martijn A.
Published: August 2010

Motivation: Protein–protein interaction (PPI) networks are a valuable resource for the interpretation of genomics data. However, such networks have interaction enrichment biases for proteins that are often studied. These biases skew quantitative results from comparing PPI networks with genomics data. Here, we introduce an approach named physical interaction enrichment (PIE) to eliminate these biases.

Methodology: PIE employs a normalization that ensures equal node degree (edge) distribution of a test set and of the random networks it is compared with. It quantifies whether a set of proteins have more interactions between themselves than proteins in random networks, and can therewith be regarded as physically cohesive.

Results: Among other datasets, we applied PIE to genetic morbid disease (GMD) genes and to genes whose expression is induced upon infection with human-metapneumovirus (HMPV). Both sets contain proteins that are often studied and that have relatively many interactions in the PPI network. Although interactions between proteins of both sets are found to be overrepresented in PPI networks, the GMD proteins are not more likely to interact with each other than random proteins when this overrepresentation is taken into account. In contrast the HMPV-induced genes, representing a biologically more coherent set, encode proteins that do tend to interact with each other and can be used to predict new HMPV-induced genes. By handling biases in PPI networks, PIE can be a valuable tool to quantify the degree to which a set of genes are involved in the same biological process.

Contact:  i.sama@cmbi.ru.nl; m.huynen@cmbi.ru.nl

Supplementary information:  Supplementary data are available at Bioinformatics online.
International variations in the clinical, diagnostic, and treatment characteristics of emergency department patients with acute heart failure syndromes
Authors: Collins Sean P. , Pang Peter S. , Lindsell Christopher J. , Kyriacou Demetrios N. , Storrow Alan B. , Hollander Judd E. , Douglas Kirk J. , Miller Chadwick D. , Nowak Richard , Frank Peacock W. , Tavares Miguel , Mebazaa Alexandre , Gheorghiade Mihai
Published: August 2010

Aims

Results from investigations in one area of the world may not translate to another if patient characteristics and practices differ. We examine differences in the presentation and management of emergency department (ED) patients with dyspnoea from acute heart failure syndromes (AHFS) between the USA, Western Europe, and Eastern Europe.

Methods and results

The URGENT Dyspnoea study was a multinational prospective observational study of dyspnoeic ED patients with AHFS from 18 countries. Acute heart failure syndrome patients from the USA and Western and Eastern Europe underwent dyspnoea assessments within 1 h of the first physician evaluation. Patient characteristics, evaluation, and treatments were compared between geographical regions using analysis of variance and χ2 tests. Four hundred and ninety‐three patients with AHFS met the inclusion criteria. Participants in the USA were more frequently non‐white, younger, on chronic beta‐blocker therapy, and with an ejection fraction ≤40% when compared with Eastern and Western Europe. Patients from Eastern Europe were more likely to present with de novo heart failure and have ischaemic electrocardiogram changes. Pulmonary oedema was more common on chest radiograph in Western Europe, but natriuretic peptide levels were elevated in all three regions. Diuretic use was similar across all the regions. Intravenous nitroglycerin was used more frequently in Eastern (32.8%) and Western Europe (24.4%) compared with the USA (2.5%).

Conclusion

International differences in AHFS presentations and management between regions suggest results from clinical trials in one region may not translate directly to another. These differences should be considered when designing trials and interpreting the results from clinical investigations.
Evolution of nutrient acquisition: when adaptation fills the gap between contrasting ecological theories
Authors: Boudsocq S. , Barot S. , Loeuille N.
Published: August 2010

Although plant strategies for acquiring nutrients have been widely studied from a functional point of view, their evolution is still not well understood. In this study, we investigate the evolutionary dynamics of these strategies and determine how they influence ecosystem properties. To do so, we use a simple nutrient-limited ecosystem model in which plant ability to take up nutrients is subject to adaptive dynamics. We postulate the existence of a trade-off between this ability and mortality. We show that contrasting strategies are possible as evolutionary outcomes, depending on the shape of the trade-off and, when nitrogen is considered as the limiting nutrient, on the intensity of symbiotic fixation. Our model enables us to bridge these evolutionary outcomes to classical ecological theories such as Hardin's tragedy of the commons and Tilman's rule of
R
*. Evolution does not systematically maximize plant biomass or primary productivity. On the other hand, each evolutionary outcome leads to a decrease in the availability of the limiting mineral nutrient, supporting the work of Tilman on competition between plants for a single resource. Our model shows that evolution can be used to link different classical ecological results and that adaptation may influence ecosystem properties in contrasted ways.
Purified galactooligosaccharide, derived from a mixture produced by the enzymic activity of Bifidobacterium bifidum, reduces Salmonella
enterica serovar Typhimurium adhesion and invasion in vitro and in vivo
Authors: Searle Laura E. J. , Cooley William A. , Jones Gareth , Nunez Alejandro , Crudgington Bentley , Weyer Ute , Dugdale Alexandra H. , Tzortzis George , Collins James W. , Woodward Martin J. , La Ragione Roberto M.
Published: August 2010

The prebiotic Bimuno® is a mixture containing galactooligosaccharides (GOSs), produced by the galactosyltransferase activity of Bifidobacterium bifidum NCIMB 41171 using lactose as the substrate. Previous in vivo and in vitro studies demonstrating the efficacy of Bimuno® in reducing Salmonella
enterica serovar Typhimurium (S. Typhimurium) colonization did not ascertain whether or not the protective effects could be attributed to the prebiotic component GOS. Here we wished to test the hypothesis that GOS, derived from Bimuno®, may confer the direct anti-invasive and protective effects of Bimuno®. In this study the efficacy of Bimuno®, a basal solution of Bimuno® without GOS [which contained glucose, galactose, lactose, maltodextrin and gum arabic in the same relative proportions (w/w) as they are found in Bimuno®] and purified GOS to reduce S. Typhimurium adhesion and invasion was assessed using a series of in vitro and in vivo models. The novel use of three dimensionally cultured HT-29-16E cells to study prebiotics in vitro demonstrated that the presence of ∼5 mg Bimuno® ml−1 or ∼2.5 mg GOS ml−1 significantly reduced the invasion of S. Typhimurium (SL1344nalr) (P<0.0001). Furthermore, ∼2.5 mg GOS ml−1 significantly reduced the adherence of S. Typhimurium (SL1344nalr) (P<0.0001). It was demonstrated that cells produced using this system formed multi-layered aggregates of cells that displayed excellent formation of brush borders and tight junctions. In the murine ligated ileal gut loops, the presence of Bimuno® or GOS prevented the adherence or invasion of S. Typhimurium to enterocytes, and thus reduced its associated pathology. This protection appeared to correlate with significant reductions in the neutral and acidic mucins detected in goblet cells, possibly as a consequence of stimulating the cells to secrete the mucin into the lumen. In all assays, Bimuno® without GOS conferred no such protection, indicating that the basal solution confers no protective effects against S. Typhimurium. Collectively, the studies presented here clearly indicate that the protective effects conferred by Bimuno® can be attributed to GOS.
Age-dependent chromosomal distribution of male-biased genes in Drosophila
Authors: Zhang Yong E. , Vibranovski Maria D. , Krinsky Benjamin H. , Long Manyuan
Published: August 2010

We investigated the correlation between the chromosomal location and age distribution of new male-biased genes formed by duplications via DNA intermediates (DNA-level) or by de novo origination in Drosophila. Our genome-wide analysis revealed an excess of young X-linked male-biased genes. The proportion of X-linked male-biased genes then diminishes through time, leading to an autosomal excess of male-biased genes. The switch between X-linked and autosomal enrichment of male-biased genes was also present in the distribution of both protein-coding genes on the D. pseudoobscura neo-X chromosome and microRNA genes of D. melanogaster. These observations revealed that the evolution of male-biased genes is more complicated than the previously detected one-step X→A gene traffic and the enrichment of the male-biased genes on autosomes. The pattern we detected suggests that the interaction of various evolutionary forces such as the meiotic sex chromosome inactivation (MSCI), faster-X effect, and sexual antagonism in the male germline might have shaped the chromosomal distribution of male-biased genes on different evolutionary time scales.