bluuebunny/crossref_metadata_2025 huggingface dataset:
Momentum balances on the inner continental shelf at Martha's Vineyard Coastal Observatory
Authors: Fewings Melanie R. , Lentz Steven J.
Published: December 2010

The subtidal, depth‐average momentum balances in 12 m and 27 m water depth are investigated using observations from 2001 to 2007 of water velocity, temperature, and density; bottom pressure; surface gravity waves; and wind stress. In the fluctuating across‐shelf momentum budget, the dominant terms are surface wind stress, pressure gradient, and Coriolis acceleration. The balance is a combination of (1) the geostrophic balance expected at midshelf sites and (2) the coastal setup and setdown balance driven by the across‐shelf wind stress expected where surface and bottom boundary layers overlap. At the 12 m site, the estimated wave radiation stress gradient due to surface gravity wave shoaling is also large but is uncorrelated with the observed pressure gradient. A simple model suggests the wave radiation stress gradient is balanced by an across‐shelf pressure gradient with a spatial scale too small to resolve with this mooring array. In the fluctuating along‐shelf momentum balance, the dominant terms are surface wind stress, pressure gradient, and bottom stress at the shallower site, but the other estimated terms are not negligible. Our results support the Grant and Madsen (1986) formulation for wave‐induced bottom stress. The fluctuating along‐shelf pressure gradient is mainly a local sea level response to wind forcing, not a remotely generated pressure gradient. A strong correlation between along‐shelf velocity and along‐shelf wind stress at the shallower site is captured by a simple steady model of imbalance between wind stress and pressure gradient balanced by linear bottom drag.
Coalition possibility of riparian countries via game theory and fuzzy logic models
Authors: Kucukmehmetoglu Mehmet , Şen Zekai , Özger Mehmet
Published: December 2010

In many respects, water resources allocation problems have fuzzy characteristics owing to uncertainty and imprecision not only as numerical data but also as linguistic data, in addition to the political nature of resource allocation. All classical techniques require numerical data and cannot treat linguistic data, but fuzzy inference systems (FIS) can deal with both types of data. Hence, it is suitable to reflect the dynamic nature of country benefits, reflective variations in the main drainage and subdrainage basin flows, and various system parameters in search of a coalition among a few riparian countries. The size of core, which is generated from a series of linear programming (LP) optimization models and game theory concepts, shows the potential extra benefit advantage of being in grand coalition to all parties, but it does not provide a sufficient condition to assemble a robust coalition unless an agreeable allocation scheme or principle is provided. In this respect, there is a fuzzy link between being in the grand coalition and percentage share received from a core. Hence, a proper FIS is proposed, and the necessary steps are developed with the Shapley value and the core as game theory methods, which provide a methodological base in the evaluation of possible allocation schemes among the parties. The application of the methodology is presented to search for coalition possibilities among the riparian countries: Turkey, Syria, and Iraq. Basic results are generated over the application of the Inter‐Temporal Euphrates and Tigris River Basin Model, which is an optimization model for the allocation of scarce water resources considering agricultural and urban uses, energy generation, and conveyance costs in the Euphrates‐Tigris basin.
Observations of High‐Energy Particles and Radiation From Thunderstorms: Thunderstorms and Elementary Particle Acceleration; Nor Amberd, Armenia, 6–11 September 2010
Authors: Fishman Gerald , Chilinggarian Ashot
Published: December 2010

Reports of gamma rays and neutrons observed at ground level below thunderstorms have appeared in the scientific literature for the past several decades. There have also been observations of intense flashes of gamma rays and electrons associated with thunderstorms by at least four different orbiting spacecraft since 1994. These have been termed terrestrial gamma ray flashes (TGFs). The latest development in this area of research is a comprehensive set of ground‐level measurements of the spectra of high‐energy gamma rays and electrons, along with neutrons, from a large array of cosmic ray detectors on Mount Aragats, in Armenia. The relationship of ground‐level radiation to spaceborne TGFs is unknown, and details of the origin of both phenomena are still highly uncertain.
New Type of Bacterium Expands Possibilities of Life, Scientists Indicate
Authors: Showstack Randy
Published: December 2010

Leading up to NASA's 2 December news briefing about a new astrobiology finding, segments of the blogosphere had run wild with speculation that the agency would announce that it has found life elsewhere. Although some bloggers and readers may have been disappointed in the actual announcement, scientists at the briefing at NASA headquarters in Washington, D.C., said the finding of a bacterium that can grow by using arsenic instead of phosphorus is “phenomenal,” with broad implications for searching for life on Earth and elsewhere and for other areas of research on Earth.

Felisa Wolfe‐Simon, a NASA Astrobiology Research Fellow in residence at the U.S. Geological Survey in Menlo Park, Calif., led a team that discovered and experimented on the microbe, known as strain GFAJ‐1 of the common bacteria group Gammaproteobacteria. Noting that life is mostly composed of carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus, she said, “If there is an organism on Earth doing something different, we've cracked open the door to what is possible for life elsewhere.”
AGU Council Undertakes Mission:Alignment Project
Authors: Finn Carol
Published: December 2010

Over the past 2 years, AGU has undertaken two critical initiatives designed to better position the organization for continued success. The first was a full membership vote to restructure governance to better address how both the science and the business of AGU are conducted. The second was to create a new long‐term strategic plan based on broad input from a cross section of science perspectives.

Now the newly configured AGU Council, which represents all constituent voices, is focusing on a key question: Given our strategic plan, stakeholder expectations of AGU, and what is being asked of science and our members, how does our science need to be organized, recognized and rewarded, disseminated, and promoted?
Rain impacts on CO2 exchange in the western equatorial Pacific Ocean
Authors: Turk Daniela , Zappa Christopher J. , Meinen Christopher S. , Christian James R. , Ho David T. , Dickson Andrew G. , McGillis Wade R.
Published: December 2010

The ocean plays a major role in the global carbon cycle through the atmosphere‐ocean partitioning of atmospheric carbon dioxide. Rain alters the physics and carbon chemistry at the ocean surface to increase the amount of CO2 taken up by the ocean. This paper presents the results of a preliminary study wherein rain measurements in the western equatorial Pacific are used to determine the enhanced transfer, chemical dilution and deposition effects of rain on air‐sea CO2 exchange. Including these processes, the western equatorial Pacific CO2 flux is modified from an ocean source of +0.019 mol CO2 m−2 yr−1 to an ocean sink of −0.078 mol CO2 m−2 yr−1. This new understanding of rain effects changes the ocean's role in the global carbon budget, particularly in regions with low winds and high precipitation.
Internal‐tide generation and destruction by shoaling internal tides
Authors: Kelly S. M. , Nash J. D.
Published: December 2010

Internal‐tide generation is usually predicted from local topography, surface tides, and stratification. However, internal tides are often observed to be unrelated to local spring‐neap forcing, appearing intermittently in 3–5 day bursts. Here we suggest a source of this intermittency by illustrating how remotely‐generated shoaling internal tides induce first‐order changes in local internal‐tide generation. Theory, numerical simulations, and observations show that pressure perturbations associated with shoaling internal tides can correlate with surface‐tide velocities to generate or destroy internal tides. Where shoaling internal tides have random phase, such as on the New Jersey slope, time‐averaged internal‐tide generation is unaffected, but instantaneous internal‐tide generation varies rapidly, altering internal‐tide energy and possibly affecting nonlinear internal waves, across‐shelf transport, and mixing. Where shoaling internal tides are phase‐locked to the local surface tide, such as in double‐ridge systems, time‐averaged internal‐tide generation is affected and may result in resonance.
Large‐amplitude electrostatic waves observed at a supercritical interplanetary shock
Authors: Wilson L. B. , Cattell C. A. , Kellogg P. J. , Goetz K. , Kersten K. , Kasper J. C. , Szabo A. , Wilber M.
Published: December 2010

We present the first observations at an interplanetary shock of large‐amplitude (> 100 mV/m pk‐pk) solitary waves and large‐amplitude (∼30 mV/m pk‐pk) waves exhibiting characteristics consistent with electron Bernstein waves. The Bernstein‐like waves show enhanced power at integer and half‐integer harmonics of the cyclotron frequency with a broadened power spectrum at higher frequencies, consistent with the electron cyclotron drift instability. The Bernstein‐like waves are obliquely polarized with respect to the magnetic field but parallel to the shock normal direction. Strong particle heating is observed in both the electrons and ions. The observed heating and waveforms are likely due to instabilities driven by the free energy provided by reflected ions at this supercritical interplanetary shock. These results offer new insights into collisionless shock dissipation and wave‐particle interactions in the solar wind.
Single‐day dayside density enhancements over Europe: A survey of a half‐century of ionosonde data
Authors: David Michael , Sojka Jan J.
Published: December 2010

With the National Geophysical Data Center's Space Physics Interactive Data Resource (SPIDR), we have collected ionosonde data from stations around the world from 1958 to 2006. The database consists of F‐layer peak frequency values (foF2) at hourly intervals (when data are available). We limit our study to midlatitude dayside density peak enhancements; we find that when such features appear, they are usually confined in longitude, being not wider than about 60–90 degrees, or 4–6 hours of local time. In this paper, we look only at enhancements over Europe, as data coverage is superior there. We define a “single‐day enhancement” and search the European sector of the database for such occurrences, finding 890 events during the 49‐year period. The frequency of occurrence of these events is seen to be anticorrelated with the solar activity cycle. There is also a seasonal distribution, with more events during the equinox months and the fewest during winter. We examine the geomagnetic activity levels on the days of the enhancements and find that a majority of the events are associated with small or moderate geomagnetic disturbances. Most of these disturbances are not large enough to be called “storms”; in many cases, there is a Dst drop of just 20–40 units or a Kp increase to a level of 3 or 4. These disturbances are not intense enough to cause a storm negative phase, but in many cases they are sufficient to bring about a dayside ionospheric density enhancement of 50% or more.
Multiple harmonic ULF waves in the plasma sheet boundary layer observed by Cluster
Authors: Engebretson M. J. , Kahlstorf C. R. G. , Posch J. L. , Keiling A. , Walsh A. P. , Denton R. E. , Broughton M. C. , Owen C. J. , Fornaçon K.‐H. , Rème H.
Published: December 2010

The passage of the Cluster satellites in a polar orbit through Earth's magnetotail has provided numerous observations of harmonically related Pc 1–2 ULF wave events, with the fundamental near the local proton cyclotron frequency Ωcp. Broughton et al. (2008) reported observations by Cluster of three such events in the plasma sheet boundary layer, and used the wave telescope technique to determine that their wave vectors k were nearly perpendicular to B. This paper reports the results of a search for such waves throughout the 2003 Cluster tail passage. During the 4 month period of July–October 2003, 35 multiple‐harmonic wave events were observed, all in the plasma sheet boundary layer (PSBL). From the first observed event (22 July) to the last (28 October), 13 of Cluster's 42 tail passes had at least one event. The wave events were rather evenly distributed from XGSE = −7 RE out to the Cluster apogee distance of −18 RE, with one event observed at −4 RE. ZGSE for these events ranged from −10 to −3 RE and +3 to +7 RE (i.e., there were no events for ∣Z∣ < 3 RE). The wave events, with durations from ∼1 to 50 min, were consistently associated with signatures of the PSBL: elevated fluxes of counterstreaming ions with energies ranging from ∼3 to 30 keV, and elevated fluxes of electrons with energies ranging from 0.25 to ∼5 keV. Analysis of plasma parameters suggests that although waves occurred only when the ion beta exceeded 0.1 (somewhat larger than typical for the PSBL), ion particle pressure may be of more physical importance in controlling wave occurrence. Electron distributions were more isotropic in pitch angles than the ion distributions, but some evidence of counterstreaming electrons was detected in 83% of the events. The ions also showed clear signatures of shell‐like or ring‐like distributions; i.e., with reduced fluxes below the energy of maximum flux. The suprathermal ion fluxes were asymmetric in all events studied, with more ions streaming earthward (for events both north and south of the central plasma sheet). Good agreement between the observed frequency of the fundamental harmonic and the local Ωcp suggests that the waves were observed near the region of their origin and did not propagate along B, consistent with the wave telescope analysis.
Three‐dimensional earthquake sequence simulations with evolving temperature and pore pressure due to shear heating: Effect of heterogeneous hydraulic diffusivity
Authors: Noda Hiroyuki , Lapusta Nadia
Published: December 2010

A new methodology for three‐dimensional (3‐D) simulations of earthquake sequences is presented that accounts not only for inertial effects during seismic events but also for shear‐induced temperature variations on the fault and the associated evolution of pore fluid pressure. In particular, the methodology allows to capture thermal pressurization (TP) due to frictional heating in a shear zone. One‐dimensional (1‐D) diffusion of heat and pore fluids in the fault‐normal direction is incorporated using a spectral method, which is unconditionally stable, accurate with affordable computational resources, and highly suitable to earthquake sequence calculations that use variable time steps. The approach is used to investigate the effect of heterogeneous hydraulic properties by considering a fault model with two regions of different hydraulic diffusivities and hence different potential for TP. We find that the region of more efficient TP produces larger slip in model‐spanning events. The slip deficit in the other region is filled with more frequent smaller events, creating spatiotemporal complexity of large events on the fault. Interestingly, the area of maximum slip in model‐spanning events is not associated with the maximum temperature increase because of stronger dynamic weakening in that area. The region of more efficient TP has lower interseismic shear stress, which discourages rupture nucleation there, contrary to what was concluded in prior studies. Seismic events nucleate in the region of less efficient TP where interseismic shear stress is higher. In our model, hypocenters of large events do not occur in areas of large slip or large stress drop.
How vegetation impacts affect climate metrics for ozone precursors
Authors: Collins W. J. , Sitch S. , Boucher O.
Published: December 2010

We examine the effect of ozone damage to vegetation as caused by anthropogenic emissions of ozone precursor species and quantify it in terms of its impact on terrestrial carbon stores. A simple climate model is then used to assess the expected changes in global surface temperature from the resulting perturbations to atmospheric concentrations of carbon dioxide, methane, and ozone. The concept of global temperature change potential (GTP) metric, which relates the global average surface temperature change induced by the pulse emission of a species to that induced by a unit mass of carbon dioxide, is used to characterize the impact of changes in emissions of ozone precursors on surface temperature as a function of time. For NOx emissions, the longer‐timescale methane perturbation is of the opposite sign to the perturbations in ozone and carbon dioxide, so NOx emissions are warming in the short term, but cooling in the long term. For volatile organic compound (VOC), CO, and methane emissions, all the terms are warming for an increase in emissions. The GTPs for the 20 year time horizon are strong functions of emission location, with a large component of the variability owing to the different vegetation responses on different continents. At this time horizon, the induced change in the carbon cycle is the largest single contributor to the GTP metric for NOx and VOC emissions. For NOx emissions, we estimate a GTP20 of −9 (cooling) to +24 (warming) depending on assumptions of the sensitivity of vegetation types to ozone damage.
Size distributions and chemical characterization of water‐soluble organic aerosols over the western North Pacific in summer
Authors: Miyazaki Yuzo , Kawamura Kimitaka , Sawano Maki
Published: December 2010

Size‐segregated aerosol samples were collected over the western North Pacific in summer 2008 to investigate marine biological contribution to organic aerosols. The samples were analyzed for organic carbon (OC), water‐soluble organic carbon (WSOC), and water‐soluble organic compounds including diacids (C2–C9), ω‐oxocarboxylic acids, and α‐dicarbonyls as well as methanesulfonic acid (MSA). The average concentrations of OC and oxalic acid (C2) were approximately two to three times larger in marine biologically more influenced aerosols, defined by the concentrations of MSA and azelaic acid (C9), than in less influenced aerosols. WSOC, which showed a statistically significant correlation with MSA, accounted for 15–21% of total mass of the components determined in the submicrometer range of biologically more influenced aerosols. These values are comparable to those of water‐insoluble organic carbon (WIOC) (∼14–23%), suggesting that organic aerosols in this region are enriched in secondary organic aerosols (SOA) linked to oceanic biological activity. In these aerosols, substantial fractions of C2–C4 diacids were found in the submicrometer size range. Positive correlations of oxalic acid with C3–C5 diacids and glyoxylic acid suggest that secondary production of oxalic acid occurs possibly in the aqueous aerosol phase via the oxidation of longer‐chain diacids and glyoxylic acid in the oceanic region with higher biological productivity. We found similar concentration levels and size distributions of methylglyoxal between the two types of aerosols, suggesting that formation of oxalic acid via the oxidation of methylglyoxal from marine isoprene is insignificant in the study region.
Electric charge modulation of aerosol scavenging in clouds: Rate coefficients with Monte Carlo simulation of diffusion
Authors: Tinsley Brian A.
Published: December 2010

The effects of electric charge on the scavenging by droplets of aerosol particles, particularly cloud condensation nuclei, appear to have a significant effect on cloud properties and climate. The effects on scavenging are calculated here in a trajectory model relative to the falling droplets, with a Monte Carlo simulation of particle diffusion along the trajectory. The charges are in the range 5–100 elementary charges, consistent with the measured and modeled deposition of small amounts of charge by the flow everywhere of atmospheric electric current density (part of the global circuit) through clouds. Particles move through a corrected Stokes flow field, under the influence of gravitational, phoretic, electric, and drag forces while diffusing. For the general situation of like charges on droplets and aerosol particles, the model simulates the long‐range electrical repulsive force that has a net effect of reducing the collision rates for small particles (radii less than about 0.1 μm) below the values for combined Brownian diffusion and phoretic forces. It also simulates the net effect for larger particles of the short‐range attractive electric forces in increasing the rate coefficients above the Brownian and phoretic values. Initial validation is provided by treating the case of ventilation in pure Brownian diffusion, for which new and more accurate ventilation coefficients are obtained as a function of the Péclet number. These are applicable to combined diffusion and phoretic scavenging with pure inverse square scavenging forces. The rate constants obtained for the electrical effects, comparable to those for Brownian and phoretic scavenging process, lead to time scales for scavenging in clouds of a few hours, consistent with observations of significant electrical effects on clouds associated with modulation of the global circuit.
Quantifying streamflow change caused by forest disturbance at a large spatial scale: A single watershed study
Authors: Wei Xiaohua , Zhang Mingfang
Published: December 2010

Climatic variability and forest disturbance are commonly recognized as two major drivers influencing streamflow change in large‐scale forested watersheds. The greatest challenge in evaluating quantitative hydrological effects of forest disturbance is the removal of climatic effect on hydrology. In this paper, a method was designed to quantify respective contributions of large‐scale forest disturbance and climatic variability on streamflow using the Willow River watershed (2860 km2) located in the central part of British Columbia, Canada. Long‐term (>50 years) data on hydrology, climate, and timber harvesting history represented by equivalent clear‐cutting area (ECA) were available to discern climatic and forestry influences on streamflow by three steps. First, effective precipitation, an integrated climatic index, was generated by subtracting evapotranspiration from precipitation. Second, modified double mass curves were developed by plotting accumulated annual streamflow against annual effective precipitation, which presented a much clearer picture of the cumulative effects of forest disturbance on streamflow following removal of climatic influence. The average annual streamflow changes that were attributed to forest disturbances and climatic variability were then estimated to be +58.7 and −72.4 mm, respectively. The positive (increasing) and negative (decreasing) values in streamflow change indicated opposite change directions, which suggest an offsetting effect between forest disturbance and climatic variability in the study watershed. Finally, a multivariate Autoregressive Integrated Moving Average (ARIMA) model was generated to establish quantitative relationships between accumulated annual streamflow deviation attributed to forest disturbances and annual ECA. The model was then used to project streamflow change under various timber harvesting scenarios. The methodology can be effectively applied to any large‐scale single watershed where long‐term data (>50 years) are available.
Meal Replacements in the Treatment of Adolescent Obesity: A Randomized Controlled Trial
Authors: Berkowitz Robert I. , Wadden Thomas A. , Gehrman Christine A. , Bishop‐Gilyard Chanelle T. , Moore Reneé H. , Womble Leslie G. , Cronquist Joanna L. , Trumpikas Natalie L. , Levitt‐Katz Lorraine E. , Xanthopoulos Melissa S.
Published: December 2010

Use of meal replacements (MRs) in lifestyle modification programs (LMPs) for obese adults significantly increases weight loss, compared with prescription of an isocaloric conventional diet (CD). This 12‐month randomized trial examined 113 obese adolescents (mean ± s.d. age of 15.0 ± 1.3 years and BMI of 37.1 ± 5.1 kg/m2) who were assigned to a LMP, combined with meal plans of 1,300–1,500 kcal/day of CD (self‐selected foods) or MR (three SlimFast shakes, one prepackaged meal, five vegetable/fruit servings). After month 4 (phase 1), participants originally treated with MR were unmasked to their phase 2 (months 5–12) random assignment: continued use of MR (i.e., MR+MR) or transitioned to CD (i.e., MR+CD). Participants initially treated with CD in phase 1, continued with CD (i.e., CD). All three groups were treated for an additional 8 months (phase 2). Regression models were used to evaluate percentage change in BMI from baseline to month 4 (phase 1), months 5–12 (phase 2), and baseline to month 12. At month 4, participants assigned to MR (N = 65) achieved a mean (±s.e.) 6.3 ± 0.6% reduction in BMI, compared to a significantly (P = 0.01) smaller 3.8 ± 0.8% for CD participants (N = 37). In phase 2, BMI increased significantly (P < 0.001) in all three conditions, resulting in no significant (P = 0.39) differences between groups in percentage change in BMI at month 12. Across groups, mean reduction in BMI from baseline to month 12 was 3.4 ± 0.7% (P < 0.01). Use of MR significantly improved short‐term weight loss, compared with CD, but its continued use did not improve maintenance of lost weight.
Ability to Delay Gratification and BMI in Preadolescence
Authors: Bruce Amanda S. , Black William R. , Bruce Jared M. , Daldalian Marina , Martin Laura E. , Davis Ann M.
Published: December 2010

Delay of gratification tasks require an individual to forgo an immediate reward and wait for a more desirable delayed reward. This study used an ecologically valid measure of delayed gratification to test the hypothesis that preadolescents with higher BMI would be less likely to delay gratification. Healthy Hawks is a 12‐week educational/behavioral obesity intervention at the University of Kansas Medical Center. Each week, children earn a point if they complete their goals worksheet. They can spend that point immediately on a small toy prize or save points to use on a larger prize. We retrospectively calculated the percentage of points saved over the 12 weeks for 59 children (28 females) ages 8–12 years old (mean = 10.29 ± 1.39). Spearman correlation revealed that higher BMI percentile was associated with reduced point savings (r = 0.33, P = 0.01). Similarly, obese preadolescents saved significantly fewer points than healthy weight (HW) and overweight preadolescents (t (57) = 3.14, P < 0.01). Results from our ecologically valid measure support the theory that obese children are less likely to delay gratification than overweight and HW children. Even for nonfood rewards, preadolescent children with higher BMIs prefer the immediate reward over a delayed, larger reward. This has implications for developing specific strategies within obesity treatments aimed at improving delayed gratification.
La main savante et le visage : optique et haptique
chirurgicale
Authors: Devauchelle Bernard
Published: December 2010

Pour le chirurgien de la face, l’ambiguïté du rapport entre main et visage est évidente,
car si la première fonde étymologiquement le métier chirurgical, de quel visage s’agit-il ?
De celui qui, caché derrière son masque, s’applique à réparer la défiguration ou de celui
qui, objet et sujet de son attention, s’efforce de retrouver figure humaine et identité au
fil des interventions ? L’analogie s’impose alors, celle du peintre et son modèle, du
sculpteur et de la main qu’il façonne, du pianiste et de l’œuvre qu’il interprète, de
l’écrivain et du souvenir qui déclenche le roman. C’est de cet affrontement des sens, mais
aussi de leur enchevêtrement dans ce qui pourrait être appelé la tactilisation de la vue
et la visualisation du toucher, cette communauté nécessaire entre l’optique et l’haptique
dont il sera question. Appliquée à la greffe du visage, cette inquiétante étrangeté,
l’interrogation schizophrène nous plonge derechef dans un vertige abyssal dont seule
l’éthique, cette esthétique du dedans évite de nous y engloutir.
A micromechanism study of thermosonic gold wire bonding on aluminum pad
Authors: Xu H. , Liu C. , Silberschmidt V. V. , Pramana S. S. , White T. J. , Chen Z. , Sivakumar M. , Acoff V. L.
Published: December 2010

A micromechanism of thermosonic gold wire bonding was elaborated by examining its interfacial characteristics as a result of the bonding process, including the fragmentation of the native aluminum oxide layer on Al pads, and formation of initial intermetallic compounds (IMCs). It is found that the existence of an approximately 5 nm thick native oxide layer on original Al pads has a significant effect on the bonding, and the nucleation of IMCs during the bonding process must overcome this relatively inert thin film. Bonding strength was fundamentally determined by the degree of fragmentation of the oxide films, through which the formation of IMCs can be initiated due to the direct contact of the metal surfaces to be bonded. The extent of fracture the oxide layer was strongly influenced by the level of ultrasonic power, as at its high level alumina fragmentation becomes pervasive resulting in contiguous alloy interfaces and robust bonds. The IMCs formed at the interfaces were identified as Al4Al and AuAl2 with a thickness of 150–300 nm. The formation mechanism of such IMCs was explained by the effective heat of formation theory.
Large thermal stability independent of critical current of domain wall motion in Co/Ni nanowires with step pinning sites
Authors: Fukami Shunsuke , Suzuki Tetsuhiro , Nagahara Kiyokazu , Ohshima Norikazu , Ishiwata Nobuyuki
Published: December 2010

The relation between critical current, critical field, and thermal stability of domain wall (DW) trapped at step pinning sites was studied using Co/Ni nanowires with perpendicular magnetic anisotropy (PMA). A sharp step structure was fabricated, which increased the critical field of DW motion, while the critical current was independent of the critical field. Also, the derived thermal stability (ΔE/kBT) for the step samples was much more than 60. These results indicate that the DW motion in PMA nanowires has potential for memory devices with both a small driving current and large thermal stability.
Electroluminescence imaging of organic photovoltaic modules
Authors: Hoyer U. , Wagner M. , Swonke Th. , Bachmann J. , Auer R. , Osvet A. , Brabec C. J.
Published: December 2010

We report on electroluminescence (EL) imaging of organic photovoltaic cells and modules with poly(3-hexylthiophene)/[6,6]-phenyl C61 butyric acid methyl ester as semiconductor layer. The dominant EL emission is found in a spectral regime between 1200 and 1400 nm and is identified as the radiative decay of the charge transfer complex formed between the polymer and the fullerene. Electroluminescence emission from the pristine compounds is either much weaker or completely absent. Overall, electroluminescence imaging is shown to give valuable information on the defects but also on the performance of organic solar modules.
Subordinated diffusion and continuous time random walk asymptotics
Authors: Dybiec Bartłomiej , Gudowska-Nowak Ewa
Published: December 2010

Anomalous transport is usually described either by models of continuous time random walks (CTRWs) or, otherwise, by fractional Fokker–Planck equations (FFPEs). The asymptotic relation between properly scaled CTRW and fractional diffusion process has been worked out via various approaches widely discussed in literature. Here, we focus on a correspondence between CTRWs and time and space fractional diffusion equation stemming from two different methods aimed to accurately approximate anomalous diffusion processes. One of them is the Monte Carlo simulation of uncoupled CTRW with a Lévy α-stable distribution of jumps in space and a one-parameter Mittag–Leffler distribution of waiting times. The other is based on a discretized form of a subordinated Langevin equation in which the physical time defined via the number of subsequent steps of motion is itself a random variable. Both approaches are tested for their numerical performance and verified with known analytical solutions for the Green function of a space-time fractional diffusion equation. The comparison demonstrates a trade off between precision of constructed solutions and computational costs. The method based on the subordinated Langevin equation leads to a higher accuracy of results, while the CTRW framework with a Mittag–Leffler distribution of waiting times provides efficiently an approximate fundamental solution to the FFPE and converges to the probability density function of the subordinated process in a long-time limit.
Selective amplification of the lower-frequency branch via stimulated super-radiance in a waveguided free electron laser oscillator driven by short electron bunches
Authors: Zhaunerchyk Vitali , Jongma Rienk T. , Lurie Yuri , Pinhasi Yosef , van der Zande Wim J.
Published: December 2010

In this letter, we propose a mechanism to extend the spectral range of a waveguided free electron laser (FEL) oscillator driven by a rf LINAC toward significantly longer wavelengths without changing the undulator or accelerator design parameters. This mechanism involves selective amplification of a lower-frequency branch supported in a FEL due to the waveguide dispersion. Based on simulations performed for the terahertz FEL under construction at the Radboud University Nijmegen, we conclude that these long wavelengths can be efficiently amplified via stimulated super-radiance as the electron bunches are shorter than the radiation wavelength.
Pair collisions of fluid-filled elastic capsules in shear flow: Effects of membrane properties and polymer additives
Authors: Pranay Pratik , Anekal Samartha G. , Hernandez-Ortiz Juan P. , Graham Michael D.
Published: December 2010

The dynamics and pair collisions of fluid-filled elastic capsules during Couette flow in Newtonian fluids and dilute solutions of high-molecular weight (drag-reducing) polymers are investigated via direct simulation. Capsule membranes are modeled using either a neo-Hookean constitutive model or a model introduced by Skalak et al. [“Strain energy function of red blood-cell membranes,” Biophys. J. 13, 245 (1973)], which includes an energy penalty for area changes. This model was developed to capture the elastic properties of red blood cells. Polymer molecules are modeled as bead-spring trimers with finitely extensible nonlinearly elastic springs; parameters were chosen to loosely approximate 4000 kDa poly(ethylene oxide). Simulations are performed with a novel Stokes flow formulation of the immersed boundary method for the capsules, combined with Brownian dynamics for the polymer molecules. The results for isolated capsules in shear indicate that at the very low concentrations considered here, polymers have a little effect on the capsule shape. In the case of pair collisions, the effect of polymer is strongly dependent on the elastic properties of the capsules’ membranes. For neo-Hookean capsules or for Skalak capsules with only a small penalty for area change, the net displacement in the gradient direction after collision is virtually unaffected by the polymer. For Skalak capsules with a large penalty for area change, polymers substantially decrease the net displacement when compared to the Newtonian case and the effect is enhanced upon increasing the polymer concentration. The differences between the polymer effects in the various cases are associated with the extensional flow generated in the region between the capsules as they leave the collision. The extension rate is highest when there is a strong resistance to a change in the membrane area and is substantially decreased in the presence of polymer.
Raman optical amplification properties of sodium–niobium–phosphate glasses
Authors: Donato M. G. , Gagliardi M. , Sirleto L. , Messina G. , Lipovskii A. A. , Tagantsev D. K. , Righini G. C.
Published: December 2010

In this paper, the optical dispersion properties and the Raman gain of sodium phosphate glasses containing niobium oxide at increasing concentrations have been systematically investigated, with the aim of establishing a potential enhancement of the Raman gain and its bandwidth with respect to silica. A broadening of the bandwidth and a higher peak Raman gain (approximately 17 times) than in silica glass have been observed at high niobium oxide molar content. Our findings point out that sodium–niobium–phosphate glasses could be utilized for the realization of Raman amplifiers.
Redrawing the Ramachandran plot after inclusion of hydrogen-bonding constraints
Authors: Porter Lauren L. , Rose George D.
Published: December 2010

A protein backbone has two degrees of conformational freedom per residue, described by its φ,ψ-angles. Accordingly, the energy landscape of a blocked peptide unit can be mapped in two dimensions, as shown by Ramachandran, Sasisekharan, and Ramakrishnan almost half a century ago. With atoms approximated as hard spheres, the eponymous Ramachandran plot demonstrated that steric clashes alone eliminate ¾ of φ,ψ-space, a result that has guided all subsequent work. Here, we show that adding hydrogen-bonding constraints to these steric criteria eliminates another substantial region of φ,ψ-space for a blocked peptide; for conformers within this region, an amide hydrogen is solvent-inaccessible, depriving it of a hydrogen-bonding partner. Yet, this “forbidden” region is well populated in folded proteins, which can provide longer-range intramolecular hydrogen-bond partners for these otherwise unsatisfied polar groups. Consequently, conformational space
expands
under folding conditions, a paradigm-shifting realization that prompts an experimentally verifiable conjecture about likely folding pathways.
Transport properties of glass-forming liquids suggest that dynamic crossover temperature is as important as the glass transition temperature
Authors: Mallamace Francesco , Branca Caterina , Corsaro Carmelo , Leone Nancy , Spooren Jeroen , Chen Sow-Hsin , Stanley H. Eugene
Published: December 2010

It is becoming common practice to partition glass-forming liquids into two classes based on the dependence of the shear viscosity η on temperature
T
. In an Arrhenius plot, ln 
η
vs 1/
T
, a strong liquid shows linear behavior whereas a fragile liquid exhibits an upward curvature [super-Arrhenius (SA) behavior], a situation customarily described by using the Vogel–Fulcher–Tammann law. Here we analyze existing data of the transport coefficients of 84 glass-forming liquids. We show the data are consistent, on decreasing temperature, with the onset of a well-defined dynamical crossover
η
×
, where
η
×
has the same value,
η
×
 ≈ 10
3
Poise, for all 84 liquids. The crossover temperature,
T
×
, located well above the calorimetric glass transition temperature
T

g

, marks significant variations in the system thermodynamics, evidenced by the change of the SA-like
T
dependence above
T
×
to Arrhenius behavior below
T
×
. We also show that below
T
×
the familiar Stokes–Einstein relation
D
/
T
 ∼ 
η
-1
breaks down and is replaced by a fractional form
D
/
T
 ∼ 
η

-
ζ

, with
ζ
 ≈ 0.85.
Impact of fish feed on four benthic invertebrate phyla abundance and taxa richness: benthic ecology implications
Authors: Matute M. Moluwa
Published: December 2010

The impact of fish feed on four benthic invertebrate phyla in channel catfish ponds was investigated. Benthic soil samples were collected from five fed and five unfed identical catfish ponds. Samples were collected from each pond December to February and the macro- and meo-invertebrates extracted. A paired-t-test was used to compare population densities, taxa richness, and hydrogen ion concentrations in fed and unfed ponds. Mean values for the entire sampling period were used for the analysis. The data collected and its analysis consistently revealed that fish feed had a reductive effect on the benthic invertebrates investigated. Density of the Mollusca and Gastrotricha were significantly reduced (P > 0.001) by fish feed. Fish feed had an eliminative effect on the Rotifera and Tardigrada as these phyla were not recorded in the fed ponds. The pH data revealed that fish feed significantly (P > 0.01) increased the acidity of the benthic soil as compared to the approximately neutral pH of the unfed ponds. Results of this study suggest that while fed ponds produce more fish, fish feed drastically decreased abundances and taxa richness of the benthic invertebrates investigated. Because fish feeding has a reductive impact on invertebrate taxa richness and taxa abundance, this could result in a reduction of ecological processes and functions ascribed to these invertebrates in their natural ecological habitat. The significant reduction of invertebrate biomass in fed ponds attests to this.
Psychotic Symptoms and Prior Use of Psychiatric Services in Psychotic Offenders Detained Under the Dutch Entrustment Act (TBS): An Exploratory Study
Authors: Goethals K.R. , Buitelaar J.K. , van Marle H.J. C.
Published: December 2010

According to the literature, most forensic psychotic patients have been in contact with general psychiatry before the index offense. However, the services received are not always in agreement with their needs. Comorbidity with a conduct disorder or antisocial personality disorder can influence the first admission to psychiatry. Four groups of patients with a history of severe violent offenses, but not sex offenses, were recruited from forensic psychiatric hospitals (TBS-hospitals) and one general hospital ( N= 137). The design was retrospective, all information was extracted from existing files, and a list of sociodemographic, psychiatric, and criminological variables was used. A SPSS statistical package was used to analyze the data. It was hypothesized that psychotic offenders had more positive and negative psychotic symptoms and that they made less use of psychiatric services and psychotropic drugs, compared to psychotic patients in general psychiatry. Psychotic offenders had received less treatment, both in childhood and as adult, compared to psychotic patients in general psychiatry. General psychiatry could prevent psychotic patients tfrom becoming offenders, while forensic psychiatry can be of significant assistance to general psychiatry in learning how to perform risk assessment and how to deal with the antisocial characteristics in psychotic patients.
Surface recombination of oxygen atoms in O2 plasma at increased pressure: I. The recombination probability and phenomenological model of surface processes
Authors: Lopaev D V , Malykhin E M , Zyryanov S M
Published: December 2010

This work deals with the study of oxygen atom loss on a quartz surface in a glow discharge plasma in pure O2 at increased pressures (5–50 Torr). O atom loss probabilities are obtained from the radial distributions of oxygen dissociation degree measured by the actinometry method. It is shown that the applicability of the actinometry method at high pressures requires the knowledge of the spatial distribution of a reduced electric field for the correct calculation of the electronic excitation rates of oxygen and actinometer atoms. The analysis of the obtained data within the framework of a simple phenomenological model of the surface processes revealed that O atom surface recombination with physisorbed oxygen atoms and molecules (producing O2 and O3, respectively) is the main loss channel for oxygen atoms in O2 plasmas at increased pressures. The oxygen atom loss probability can noticeably grow in comparison with the case of low pressure due to the essential increase in the surface occupation degree by physisorbed atoms and molecules.
A global resonance phenomenon at the TJ-II stellarator
Authors: van Milligen B.Ph. , Estrada T. , Jiménez-Gómez R. , Melnikov A. , Hidalgo C. , Fontdecaba J.M. , Krupnik L. , Eliseev L.G. , Perfilov S.V.
Published: December 2010

A new phenomenon at the TJ-II stellarator is reported. The line-integrated density measured by a microwave interferometer systematically shows bursts of fluctuations at regularly spaced values of the mean density across a very large number of discharges. Related modes are also observed with other diagnostics, such as the magnetic pickup coils and the heavy ion beam probe. The mode is tentatively identified with an acoustic mode, and its relation to confinement transitions at TJ-II is discussed.
Determinants of extracellular matrix remodelling are differentially expressed in paediatric and adult dilated cardiomyopathy
Authors: Hsia Tain‐Yen , Ringewald Jeremy M. , Stroud Robert E. , Forbus Geoffrey A. , Bradley Scott M. , Chung Wendy K. , Spinale Francis G.
Published: December 2010

Aims

The left ventricular phenotype of idiopathic dilated cardiomyopathy (DCM) can appear similar in paediatric and adult patients. However, the aetiology of paediatric DCM is usually idiopathic, and often leads an aggressive clinical course. A structural underpinning of DCM is extracellular matrix changes, which are determined by a balance between matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs). This study tested the hypothesis that different MMP/TIMP profiles occur in paediatric and adult DCM patients.

Methods and results

Left ventricular samples from paediatric (age 9 ± 5 years;n= 10) and adult (age 62 ± 3 years;n= 20) DCM (at time of transplant) were subjected to an MMP/TIMP multiplex array and immunoassay in order to measure the MMP subclasses; collagenases (MMP−8, −13), gelatinases (MMP−2, −9), stromelysin/matrilysin (MMP−3, −7), membrane type (MT1‐MMP), as well as for the four known TIMPs. MMP−8 and −9 levels increased by over 150% (P< 0.05), whereas MMP−3 and −7 levels decreased by over 30% (P< 0.05) in paediatric DCM when compared with adult DCM. TIMP−1 and −2 levels increased two‐fold (P< 0.05), but TIMP‐3 fell by 41% (P< 0.05) in paediatric DCM. Myocardial levels of specific interleukins (IL‐1beta, IL‐2, IL‐8) were increased by approximately 50% in paediatric DCM.

Conclusions

These unique findings demonstrated that a specific MMP/TIMP profile occurs in paediatric DCM when compared with adult DCM, and that local cytokine induction may contribute to this process. These distinct differences in the determinants of myocardial matrix structure and function may contribute to the natural history of DCM in children.
There is no trade-off between speed and force in a dynamic lever system
Authors: McHenry Matthew J.
Published: December 2010

Lever systems within a skeleton transmit force with a capacity determined by the mechanical advantage,A. Ais the distance from input force to a joint, divided by the distance from the joint to the output force. A lever with a relatively highAin static equilibrium has a great capacity to generate force but moves a load over a small distance. Therefore, the geometry of a skeletal lever presents a trade-off between force and speed under quasi-static conditions. The present study considers skeletal dynamics that do not assume static equilibrium by modelling kicking by a locust leg, which is powered by stored elastic energy. This model predicts that the output force of this lever is proportional toA, but its maximum speed is independent ofA. Therefore, no trade-off between force and velocity exists in a lever system with spring-mass dynamics. This demonstrates that the motion of a skeleton depends on the major forces that govern its dynamics and cannot be inferred from skeletal geometry alone.