bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing EMS Scope of Practice for Utility and Risk: the New Mexico EMS Interventions Assessment Project, Phase One Results
Authors: Munk Marc-David , Fullerton Lynne , Banks Laura , Morley Sarah , McDaniels Robert , Castle Stuart , Thornton Kyle , Richards Michael E.
Published: August 2012

Introduction

Few emergency medical services (EMS) interventions in New Mexico have been assessed for efficacy, potential harm, or potential benefit. There is concern that many interventions added over the years may be outdated, harmful, or ineffective in the EMS setting. A formal process for reviewing the state EMS scope of practice using literature review and expert consensus is discussed. In Phase One of the project, interventions in the New Mexico EMS scope of practice were prioritized for further review by surveying a national cadre of EMS experts to evaluate EMS interventions using a utilitarian harm/benefit metric.

Methods

An electronic survey based on the 2010 New Mexico EMS Scope of Practice statute was administered from March through June, 2011. A national cadre of 104 respondents was identified. Respondents were either State EMS medical directors or EMS fellowship directors. Respondents were asked to rate the potential harm and the potential benefit of specific EMS interventions on a 5-point ordinal scale. Median harm and benefit scores were calculated.

Results

A total of 88 completed surveys were received following 208 emailed invitations to 104 respondents (43% response rate). Twenty-two (22) highest-priority interventions (those with a harm/benefit median score ratio of >1) were identified. Seven additional second-priority interventions were also identified. These interventions will be advanced for formal literature review and expert consensus.

Conclusions

The New Mexico EMS Interventions Project offers a novel model for assessing a prehospital scope of practice.

MunkMD,FullertonL,BanksL,MorleyS,McDanielsR,CastleS,ThorntonK,RichardsME.Assessing EMS scope of practice for utility and risk: the New Mexico EMS Interventions Assessment Project, Phase One results.Prehosp Disaster Med.2012;27(5):1-6.
An indirect comparison of the efficacy and safety of desvenlafaxine and venlafaxine using placebo as the common comparator
Authors: Coleman Kristina A. , Xavier Vanessa Y. , Palmer Trish L. , Meaney James V. , Radalj Libby M. , Canny Louise M.
Published: August 2012

Background

This meta-analysis compared the efficacy and safety of desvenlafaxine and venlafaxine at the Australian approved doses.

Methods

A systematic literature search was conducted to identify all placebo-controlled studies of desvenlafaxine and venlafaxine in the treatment of major depression. The pivotal outcome measure used to assess comparative efficacy was the mean change in Hamilton Rating Scale for Depression-17 score from baseline. Tolerability and safety were compared by an evaluation of reported adverse events. Standard and Bayesian methods were used to conduct the indirect comparisons.

Findings

Using a mixed model repeated measures analysis, the pooled weighted mean difference for the mean change in Hamilton Rating Scale for Depression-17 score from baseline was −2.81 (−3.72, −1.91; p < 0.001) for desvenlafaxine and −2.61 (−3.17, −2.05; p < 0.001) for venlafaxine. An indirect Bayesian analysis adjusted for baseline Hamilton Rating Scale for Depression-17 score showed no significant difference between the two treatments (weighted mean difference −0.27; −1.17, 0.65). A standard indirect comparison of any adverse events showed no significant difference between desvenlafaxine and venlafaxine (relative risk 1.01; 0.96, 1.06; p = 0.70 and risk difference −0.01; −0.05, 0.03; p = 0.59). Standard indirect comparisons of both nausea and drop-outs identified potential differences between treatments, with the risk difference analyses suggesting a trend in favor of desvenlafaxine (nausea: relative risk 0.97; 0.77, 1.22; p = 0.80/RD −0.07; −0.12, −0.01; p = 0.02; and drop-outs due to adverse events: RR 0.86; 0.58, 1.29; p = 0.48/RD −0.04; −0.08, 0.00; p = 0.06).

Conclusions

Based on the results of this meta-analysis, desvenlafaxine was shown to be non-inferior to venlafaxine in terms of efficacy, and has an advantage in terms of less nausea.
Prevalence and determinants of the metabolic syndrome among Tunisian adults: results of the Transition and Health Impact in North Africa (TAHINA) project
Authors: Belfki Hanen , Ali Samir Ben , Aounallah-Skhiri Hajer , Traissac Pierre , Bougatef Souha , Maire Bernard , Delpeuch Francis , Achour Noureddine , Ben Romdhane Habiba
Published: August 2012

Objective

To determine the prevalence of metabolic syndrome (MetS) and its components and to evaluate the relationship between this diagnosis and cardiovascular risk factors, demographic and socio-economic variables.

Design

A cross-sectional study using a questionnaire including information on sociodemographic and CVD risk factors. Blood pressure, anthropometric indices, fasting glucose and lipid profile were measured. MetS was defined according to the criteria of the National Cholesterol Education Program, Adult Treatment Panel III.

Setting

The whole Tunisian territory; Transition and Health Impact in North Africa (TAHINA) project.

Subjects

A total of 4654 individuals (1840 men and 2814 women), aged 35 to 74 years, who participated in the Tunisian national survey.

Results

The overall prevalence of MetS was 30·0 %, higher in women (36·1 %) than in men (20·6 %; P < 0·001). In both genders MetS prevalence increased significantly with age (P < 0·001), but this increase was more important in women. Multiple regression analyses showed that the odds for MetS increased significantly with urban area for both men and women (P < 0·05 and P < 0·001, respectively). The multivariate models showed also that the odds for MetS increased significantly with increasing level of education and in those with a family history of CVD for men (both P < 0·05) and after the menopausal transition for women (P < 0·05).

Conclusions

The study highlights the MetS problem in a middle-income developing country. There is an urgent need for a comprehensive, integrated, population-based intervention programme to ameliorate the growing problem of MetS in Tunisians.
Airing Authenticity: The BBC Jam Sessions from New York, 1938/39
Authors: BAADE CHRISTINA
Published: August 2012

In November 1938 and January 1939, the BBC relayed two American Jam Sessions from New York to Britain. Regarded as historic by critics and producers, the live relays broke from BBC tradition in their presentation of improvised jazz and in their production as “informal parties.” Both broadcasts featured Alistair Cooke as announcer and “a galaxy of swing stars” (including Sidney Bechet, Teddy Wilson, and Tommy Dorsey) assembled by the New York bandleader Joe Marsala; however, British jazz enthusiasts responded to them very differently. Whereas the second session was widely praised, the first session inspired controversy, particularly after a leading critic deemed it a “washout.”

The divergent reception demonstrated the challenges of maintaining the jam session's status as a paragon of authenticity as it underwent three key transitions during the late 1930s: the transformation from in- and inter-group activity to public event; the transmission from New York's jazz and swing cultures to Britain's enthusiast subculture; and the transmutation from live performance to live broadcast. This article examines the context, planning, content, and reception of the 1938/39 BBC jam sessions as a case study in how authenticity in jazz was rearticulated in public, mediated, and transnational spaces.
PerformingAcadie: Marketing Pan-Acadian Identity in the Music of Vishtèn
Authors: FORSYTH MEGHAN
Published: August 2012

This article examines the influence of strategic musical alliances on the formation of a unique regional Acadian cultural identity. The Acadian communities of Prince Edward Island and les Îles-de-la-Madeleine (Québec), located on Canada's east coast, share a tumultuous socio-political history that is traced tole Grand Dérangement, the eighteenth-century deportation of thousands of Acadians from eastern Canada. The geographic location of the islands, their contemporary political affiliations, and divergent cultural retentions suggest distinct experiences of Acadian identity; nonetheless, renewed interest in inter-island partnerships has arisen over the past decade, often along musical lines. These alliances have been fostered largely by a young generation of musicians from the Acadian group, Vishtèn. Through their strategic musical, narrative, and marketing choices, members of Vishtèn have striven vigorously to advance the project of a shared island Acadian identity, while claiming a place in the global “traditional” music market. I conclude that this exchange has fostered an emic perception of a unified francophone Acadian community that has transformed the cultural geography of this region of “Acadia” and contributed to local processes of Acadian cultural revitalization.
Remote sensing of neutral temperatures in the Earth's thermosphere using the Lyman‐Birge‐Hopfield bands of N2: Comparisons with satellite drag data
Authors: Krywonos Andrey , Murray D. J. , Eastes R. W. , Aksnes A. , Budzien S. A. , Daniell R. E.
Published: August 2012

This paper presents remotely sensed neutral temperatures obtained from ultraviolet observations and compares them with temperatures from the NRLMSISE‐00 version of the Mass Spectrometer and Incoherent Scatter (MSIS) model (unconstrained and constrained to match the total densities from satellite drag). Latitudinal profiles of the temperatures in the Earth's thermosphere are obtained by inversion of high‐resolution (∼1.3 Å) observations of the (1,1) and (5,4) Lyman‐Birge‐Hopfield (LBH) bands of N2. The spectra are from the High resolution Ionospheric and Thermospheric Spectrograph (HITS) instrument aboard the Advanced Research and Global Observation Satellite (ARGOS). The results indicate that on each day examined there was consistency between the remotely sensed thermospheric temperatures, the densities from coincident satellite drag measurements at adjacent altitudes, and the NRLMSISE‐00 model.
Riparian biogeochemical hot moments induced by stream fluctuations
Authors: Gu Chuanhui , Anderson William , Maggi Federico
Published: August 2012

Hyporheic exchanges in riparian zones induced by stream stage fluctuations, referred to as bank storage, can influence contaminant transport and transformation when mixing of groundwater and surface waters with distinct chemical signatures occur, which might lead to a high biochemical activity. The effect of bank storage on nutrient transport was analyzed here using a two‐dimensional, variably saturated and multispecies reactive transport model, which accounted for the water flow and solute transport and reactions within riparian zones. After verification with field observations, our model demonstrated that high biogeochemical activities occurred at the near‐stream riparian zone during stage fluctuation, a process referred to as bank storage hot moment (BSHM). We used Monte Carlo simulations to study the uncertainty of BSHM and related nutrient dynamics to biogeochemical and hydrological factors. The results indicated that stream fluctuations can lead to maximum bank storage volume ranging from 0 to 259 m3 m−1 of stream linear length (median = 9.7 m3 and SD = 53.2 m3). Taking denitrification as an example, BSHM can lead to considerable NO3− removal with a median removal rate of 2.1 g d−1 and SD of 17.2 g d−1 per meter of stream linear length. The NO3− uptake velocity (median = 2.7 × 10−5 and SD = 2.4 × 10−4 m min−1) was comparable to that of in‐stream transient storage from the literature. This result suggests that BSHM may be a significant process contributing to the nutrient budget at the ecosystem level. Finally, a theoretical framework representing the coupled hydrobiogeochemical controls on riparian hot spots was developed to help predicting when BSHM can become important in a particular stream.
A first step toward AGU's new two‐year college initiative
Authors: Asher Pranoti M. , Adamec Bethany
Published: August 2012

The U.S. National Science Foundation–funded Unique Research Experiences for two‐year College faculty And Students (URECAS) workshop was held 11–13 July at AGU headquarters. Faculty from 2‐year and 4‐year colleges as well as representatives from federal and state agencies and other professional organizations gathered for the 2‐day planning workshop. The main goals of the workshop were as follows:

identify and develop a community of 2‐year college (2YC) Earth and space science faculty who are engaged in research experiences and programs with their students;

determine model programs and best practices within the community that make these research experiences and programs successful for faculty and students;

identify challenges that faculty must overcome to have successful faculty and student research experiences and programs;

connect faculty who want to engage in research experiences with their students to national and local resources that can assist them in being successful in these endeavors; and

highlight and develop collaborations that will allow 2YC students and faculty to attend and present their research at the AGU Fall Meeting.
Uncertainty estimation for databased bathymetry using a Bayesian network approach
Authors: Elmore Paul A. , Fabre David H. , Sawyer Raymond T. , Ladner R. Wade
Published: August 2012

A Bayesian network approach has been developed to estimate uncertainties for gridded bathymetry models that store grids of large regional or worldwide bathymetry. A previous technique to estimate uncertainty for historical data uses Monte Carlo simulations to estimate uncertainty using soundings data, but it is infeasible to implement for gridded bathymetry models. The Bayesian network is designed to estimate uncertainty using gridded bathymetry and a distribution of navigation uncertainties for the survey data used to create the grid as inputs. This paper discusses how the Monte Carlo technique is used to train the network and how to implement it to estimate gridded uncertainty. A demonstration of this approach is presented that uses the data from the original paper for the Monte Carlo technique. Both Monte Carlo and Bayesian network estimators provide higher uncertainty with bottom slope. The Bayesian network estimate is generally greater than the Monte Carlo approach, which is by design for navigation safety, but is within an order of magnitude agreement.
A sea ice free summer Arctic within 30 years: An update from CMIP5 models
Authors: Wang Muyin , Overland James E.
Published: August 2012

Three years ago we proposed that the summer Arctic would be nearly sea ice free by the 2030s; “nearly” is interpreted as sea ice extent less than 1.0 million km2. We consider this estimate to be still valid based on projections of updated climate models (CMIP5) and observational data. Similar to previous models (CMIP3), CMIP5 still shows a wide spread in hindcast and projected sea ice loss among different models. Further, there is no consensus in the scientific literature for the cause of such a spread in results for CMIP3 and CMIP5. While CMIP5 model mean sea ice extents are closer to observations than CMIP3, the rates of sea ice reduction in most model runs are slow relative to recent observations. All CMIP5 models do show loss of sea ice due to increased anthropogenic forcing relative to pre‐industrial control runs. Applying the same technique of model selection and extrapolation approach to CMIP5 as we used in our previous paper, the interval range for a nearly sea ice free Arctic is 14 to 36 years, with a median value of 28 years. Relative to a 2007 baseline, this suggests a nearly sea ice free Arctic in the 2030s.
Magneto‐elastic coupling in compressed Fe7C3 supports carbon in Earth's inner core
Authors: Chen Bin , Gao Lili , Lavina Barbara , Dera Przemyslaw , Alp Esen E. , Zhao Jiyong , Li Jie
Published: August 2012

The nature of light element(s) in the core holds key to our understanding of Earth's history of accretion and differentiation, but the core composition remains poorly constrained. Carbon has been proposed to be a major constituent of the inner core, with broad implications for the global carbon cycle, the budget of volatiles in the Earth and origin of carbon‐based life in the Solar System. However, existing estimates of the inner core's carbon content remain highly controversial because of poor constraints on the behavior of compressed iron carbides. Here we investigated the structure, elasticity, and magnetism of Eckstrom‐Adcock carbide Fe7C3up to core pressures, using synchrotron‐based single‐crystal X‐ray diffraction and Mössbauer spectroscopy techniques. We detected two discontinuities in the compression curve up to 167 gigapascals (GPa), the first of which corresponds to a magnetic collapse between 5.5 and 7.5 GPa and is attributed to a ferromagnetic to paramagnetic transition. At the second discontinuity near 53 GPa, Fe7C3softens and exhibits Invar behavior, presumably caused by a high‐spin to low‐spin transition. Considering the magneto‐elastic coupling effects, an Fe7C3‐dominant composition can match the density of the inner core, making the core potentially the largest reservoir of carbon in Earth.
Robust future precipitation declines in CMIP5 largely reflect the poleward expansion of model subtropical dry zones
Authors: Scheff Jack , Frierson Dargan M. W.
Published: August 2012

Robust subtropical precipitation declines have been a prominent feature of general circulation model (GCM) responses to future greenhouse warming. Recent work by the authors showed that for the models making up the Coupled Model Intercomparison Project phase 3 (CMIP3), this drying was found mainly in the midlatitude‐driven precipitation poleward of the model subtropical precipitation minima. Here, using more comprehensive diagnostics, we extend that work to 36 new CMIP5 models, and find that CMIP5 robust precipitation declines are also found mainly between subtropical minima and midlatitude precipitation maxima, implicating dynamic poleward expansion of dry zones rather than thermodynamic amplification of dry‐wet contrasts. We also give the full seasonal cycle of these projected declines, showing that they are much more widespread in local spring than in local fall, and that for most of the year in the Northern Hemisphere they are entirely confined to the Atlantic side of the globe.
Particle‐in‐cell simulations of the solar wind interaction with lunar crustal magnetic anomalies: Magnetic cusp regions
Authors: Poppe A. R. , Halekas J. S. , Delory G. T. , Farrell W. M.
Published: August 2012

As the solar wind is incident upon the lunar surface, it will occasionally encounter lunar crustal remanent magnetic fields. These magnetic fields are small‐scale, highly non‐dipolar, have strengths up to hundreds of nanotesla, and typically interact with the solar wind in a kinetic fashion. Simulations, theoretical analyses, and spacecraft observations have shown that crustal fields can reflect solar wind protons via a combination of magnetic and electrostatic reflection; however, analyses of surface properties have suggested that protons may still access the lunar surface in the cusp regions of crustal magnetic fields. In this first report from a planned series of studies, we use a 11/2‐dimensional, electrostatic particle‐in‐cell code to model the self‐consistent interaction between the solar wind, the cusp regions of lunar crustal remanent magnetic fields, and the lunar surface. We describe the self‐consistent electrostatic environment within crustal cusp regions and discuss the implications of this work for the role that crustal fields may play regulating space weathering of the lunar surface via proton bombardment.
High‐Pbehavior of anorthite composition and some phase relations of the CaO‐Al2O3‐SiO2 system to the lower mantle of the Earth, and their geophysical implications
Authors: Liu Xi , Ohfuji Hiroaki , Nishiyama Norimasa , He Qiang , Sanehira Takeshi , Irifune Tetsuo
Published: August 2012

Multianvil experiments with long experimental durations have been made with the anorthite composition CaAl2Si2O8at pressure‐temperature (P‐T) conditions of 14–25 GPa and 1400–2400°C. At subsolidus conditions, these experiments demonstrated three phase assemblages, grossular (Gr) + kyanite (Ky) + stishovite (St) at ∼14 GPa, Gr + calcium‐alumino‐silicate phase (CAS) + St at ∼18 GPa, and CAS + CaSiO3‐perovskite (CaPv) + St at above ∼20 GPa, which are related by the reactions Gr + Ky = CAS + St and Gr + St = CAS + CaPv. Following the method of Schreinemakers, we combined our data with the literature data to deduce aP‐Tphase diagram for a portion of the CaO‐Al2O3‐SiO2system at subsolidus conditions, which subsequently helped to solve some long‐lasting discrepancies in the high‐Pbehavior of the compositions of anorthite and grossular. The crystal chemistry of the CAS and CaPv solid solutions was examined, and new substitution mechanisms were firmly established. Along the solidus, the melting reaction at ∼14 GPa is peritectic while that at ∼22 GPa is eutectic. For both pressures, St is the first phase to melt out and the melt is generally andesitic. For the An composition, its density starts to be significantly higher than the density of pyrolite at ∼2.5 GPa, a much lower pressure than that for the Or, Ab or Qtz composition (∼7.5–10 GPa), so that the An‐enriched continental crust material should readily plunge into the upper mantle.
40Ar/39Ar geochronology of submarine Mauna Loa volcano, Hawaii
Authors: Jicha Brian R. , Rhodes J. Michael , Singer Brad S. , Garcia Michael O.
Published: August 2012

New geochronologic constraints refine the growth history of Mauna Loa volcano and enhance interpretations of the petrologic, geochemical, and isotopic evolution of Hawaiian magmatism. We report results of 40Ar/39Ar incremental heating experiments on low‐K, tholeiitic lavas from the 1.6 km high Kahuku landslide scarp cutting Mauna Loa's submarine southwest rift zone, and from lavas in a deeper section of the rift. Obtaining precise40Ar/39Ar ages from young, tholeiitic lavas containing only 0.2–0.3 wt.% K2O is challenging due to their extremely low radiogenic 40Ar contents. Analyses of groundmass from 45 lavas yield 14 new age determinations (31% success rate) with plateau and isochron ages that agree with stratigraphic constraints. Lavas collected from a 1250 m thick section in the landslide scarp headwall were all erupted around 470 ± 10 ka, implying an extraordinary period of accumulation of ∼25 mm/yr, possibly correlating with the peak of the shield‐building stage. This rate is three times higher than the estimated vertical lava accumulation rate for shield‐building at Mauna Kea (8.6 ± 3.1 mm/yr) based on results from the Hawaii Scientific Drilling Project. Between ∼470 and 273 ka, the lava accumulation rate along the southwest rift zone decreased dramatically to ∼1 mm/yr. We propose that the marked reduction in lava accumulation rate does not mark the onset of post‐shield volcanism as previously suggested, but rather indicates the upward migration of the magma system as Mauna Loa evolved from a submarine stage of growth to one that is predominantly subaerial, thereby cutting off supply to the distal rift zone. Prior to ∼250 ka, lavas with Loihi‐like isotopic signatures were erupted along with lavas having typical Mauna Loa values, implying greater heterogeneity in the plume source earlier in Mauna Loa's growth. In addition to refining accumulation rates and the isotopic evolution of the lavas erupted along the southwest rift zone, our new40Ar/39Ar results constrain the eruption of the Ninole Basalts from 227 to 108 ka and provide maximum estimates on the timing of the Ka Lae and South Kona landslides.
Localized imaging of the uppermost mantle with USArray Pn data
Authors: Buehler J. S. , Shearer P. M.
Published: August 2012

USArray has now provided several years of high‐quality seismic data and improved ray coverage for much of the western United States. This allows increased resolution for regional studies of the lithosphere and deeper structure of the North American continent. In this study, we use Pn phases in the USArray data set to solve for velocity structure in the uppermost mantle in the western United States. This article focuses on localized imaging techniques that complement traditional Pn tomography analysis. We apply waveform cross‐correlation to obtain inter‐station travel times between the closely and uniformly spaced USArray stations. This allows us to use traces without phase picks and reduces errors associated with the picking. We obtain differential times that can directly be used to fit locally for slowness and, depending on the approach, for the direction and curvature of the incoming wavefront. The various measurements of incoming wavefronts at different sub‐arrays provide constraints on azimuthal variations in velocity. The traditional tomography approach and the local fitting method reveal similar large‐scale features. No regularization is applied with the local method, and the resulting velocity maps reveal smaller‐scale structures than the tomographic images.
Validation of the present day annual cycle in heavy precipitation over the British Islands simulated by 14 RCMs
Authors: Schindler A. , Maraun D. , Luterbacher J.
Published: August 2012

The representation of the annual cycle of heavy daily precipitation events across the United Kingdom within 14 regional climate models (RCMs) and the European observation data set (E‐OBS) over the 1961–2000 period is investigated. We model extreme precipitation as an inhomogeneous Poisson process with a non‐stationary threshold and use a sinusoidal model for the location and scale parameter of the corresponding generalized extreme value distribution and a constant shape parameter. First we fit the statistical model to the UK Met Office 5 km gridded precipitation data set (UKMO). Second the statistical model is fitted to 14 reanalysis driven 25 km resolution RCMs from the ENSEMBLES project and to E‐OBS. The resulting characteristics from the RCMs and from E‐OBS are compared with those from UKMO. We study the peak time of the annual cycle of the monthly return levels, the relative amplitude of their annual cycle and the relative bias of their absolute values. We show that the performance of the RCMs depends strongly on the region. The RCMs show deficits in modeling the characteristics of the annual cycle, especially in modeling its relative amplitude and mainly in Eastern England. However the peak time of the annual cycle is adequately simulated by most RCMs. E‐OBS exhibits considerable biases in the absolute values of all monthly return levels, but the relative amplitude and the phase of the annual cycle of heavy precipitation are well represented. Our results imply that studies which rely on the explicit annual cycle of simulated heavy precipitation should be carefully considered.
Hypoxic preconditioning enhances the therapeutic potential of the secretome from cultured human mesenchymal stem cells in experimental traumatic brain injury
Authors: Chang Ching-Ping , Chio Chung-Ching , Cheong Chong-Un , Chao Chien-Ming , Cheng Bor-Chieh , Lin Mao-Tsun
Published: August 2012

Bone-marrow-derived human MSCs (mesenchymal stem cells) support repair when administered to animals with TBI (traumatic brain injury) in large part through secreted trophic factors. We directly tested the ability of the culture medium (or secretome) collected from human MSCs under normoxic or hypoxic conditions to protect neurons in a rat model of TBI. Concentrated conditioned medium from cultured human MSCs or control medium was infused through the tail vein of rats subjected to TBI. We have demonstrated that MSCs cultured in hypoxia were superior to those cultured in normoxia in inducing expression of both HGF (hepatocyte growth factor) and VEGF (vascular endothelial growth factor) in the cultured medium. We showed further that rats treated with the secretome from both normoxic- and hypoxic-preconditioned MSCs performed significantly better than the controls in both motor and cognitive functional test. Subsequent post-mortem evaluation of brain damage at the 4-day time point confirmed that both normoxic- and hypoxic-preconditioned MSC secretome-treated rats had significantly greater numbers of newly forming neurons, but significantly less than the controls in brain damaged volume and apoptosis. The TBI rats treated with hypoxic-preconditioned MSC secretome performed significantly better in both motor and cognitive function tests and neurogenesis, and had significantly less brain damage than the TBI rats treated with the normoxic-preconditioned MSC secretome. Collectively, these findings suggest that MSCs secrete bioactive factors, including HGF and VEGF, that stimulate neurogenesis and improve outcomes of TBI in a rat model. Hypoxic preconditioning enhances the secretion of these bioactive factors from the MSCs and the therapeutic potential of the cultured MSC secretome in experimental TBI.
Determination of the effective distribution coefficient (K) for silicon impurities
Authors: Mei P. R. , Moreira S. P. , Côrtes A. D. S. , Cardoso E. , Marques F. C.
Published: August 2012

For the production of photovoltaic cells, the silicon purity can be intermediate between metallurgical grade silicon (MG-Si, 98%–99.9% pure) and electronic grade silicon (>99.9999% pure). This silicon, with intermediate purity and that still meets solar cell requirements, is called upgraded metallurgical grade silicon (UMG-Si). One method of producing UMG-Si is applying a controlled solidification process, like unidirectional solidification (heat exchange method), zone melting (or zone refining), or Czochralski growth to MG-Si. These processes use the impurities solubility difference in solid and liquid silicon known as effective distribution coefficient (K). For these reasons, to study the solidification process, it is necessary to determine K for silicon impurities, which is the objective of this study. MG-Si (99.85% purity or 1500 ppm of impurities) was processed by 1 pass of zone melting at 1 mm/min using an electron beam furnace with water cooled copper crucible. The effective distribution coefficient (K) for impurities with Ko ≤ 10−1 was found to follow the relation K = 0.03 Ko−0.063. For boron, K = 0.8. Impurities with Ko between 10−3 and 10−8 presented similar effective distribution coefficients (K = 0.07 ± 0.02), meaning that the effective distribution coefficient of a specific impurity depends on the total amount of impurities. The measured impurities profiles in silicon were compared with those obtained by Pfann’s equations using the effective distribution coefficients and showed comparative results.
Computer simulation of the role of torsional flexibility on mass and momentum transport for a series of linear alkanes
Authors: Braga Carlos , Travis Karl P.
Published: August 2012

We present the results obtained from a systematic equilibrium molecular dynamics study of the effect of torsional flexibility on the diffusion and viscosity of a series of linear alkanes. To make unambiguous comparisons between molecules with torsional flexibility and those without, we use the frozen distribution sampling (FDS) method introduced by Travis et al. [J. Chem. Phys. 98, 1524 (1993)10.1063/1.464317; Travis et al. J. Chem. Phys. 102, 2174 (1995)]10.1063/1.468739 but modified and updated for increased efficiency. We first demonstrate comprehensively that FDS guarantees corresponding thermodynamic states. We then show that removal of torsional flexibility results in a significant lowering of the diffusion coefficient (and corresponding increase in shear viscosity) and furthermore that this effect increases with increasing chain length. The results are discussed in terms of the possible mechanism giving rise to this dynamic coupling phenomenon.
Theory of supramolecular co-polymerization in a two-component system
Authors: Jabbari-Farouji S. , van der Schoot Paul
Published: August 2012

As a first step to understand the role of molecular or chemical polydispersity in self-assembly, we put forward a coarse-grained model that describes the spontaneous formation of quasi-linear polymers in solutions containing two self-assembling species. Our theoretical framework is based on a two-component self-assembled Ising model in which the chemical bidispersity, i.e., the presence of two distinct chemical entities, is parameterized in terms of the strengths of the binding free energies that depend on the monomer species involved in the pairing interaction. Depending upon the relative values of the binding free energies involved, different morphologies of assemblies that include both components are formed, exhibiting random, blocky or alternating ordering of the two components in the assemblies. Analyzing the model for the case of blocky ordering, which is of most practical interest, we find that the transition from conditions of minimal assembly to those characterized by strong polymerization can be described by a critical concentration that depends on the concentration ratio of the two species. Interestingly, the distribution of monomers in the assemblies is different from that in the original distribution, i.e., the ratio of the concentrations of the two components put into the system. The monomers with a smaller binding free energy are more abundant in short assemblies and monomers with a larger binding affinity are more abundant in longer assemblies. Under certain conditions the two components congregate into separate supramolecular polymeric species and in that sense phase separate. We find strong deviations from the expected growth law for supramolecular polymers even for modest amounts of a second component, provided it is chemically sufficiently distinct from the main one.
Femtosecond evolution of the pyrrole molecule excited in the near part of its UV spectrum
Authors: Montero Raúl , Peralta Conde Álvaro , Ovejas Virginia , Fernández-Fernández Marta , Castaño Fernando , Vázquez de Aldana Javier R. , Longarte Asier
Published: August 2012

The evolution of the isolated pyrrole molecule has been followed after excitation in the 265–217 nm range by using femtosecond time delayed ionization. The transients collected in the whole excitation range show the vanishing of the ionization signal in the femtosecond time scale, caused by the relaxation along a πσ* type state (3s a1←π 1a2), which is the lowest excited electronic state of the molecule. This surface is dissociative along the NH bond, yielding a 15 ± 3 fs lifetime that reflects the loss of the ionization cross-section induced by the ultrafast wavepacket motion. Although a weak πσ* absorption is detected, the state is mainly reached through internal conversion of the higher bright ππ* transitions, which occurs with a 19 ± 3 fs lifetime. In addition to its resonant excitation, the intense ππ* absorption extending in the 220–190 nm interval is also out-of-resonance populated at energies far to the red from its absorption onset. This coherent adiabatic excitation of the ππ* transition should follow the excitation pulse (coherent population return effect), but instead the system relaxes toward the lower πσ* surface through a conical intersection during the interaction time, leading to the population of πσ* state at wavelengths as long as 265 nm. According to the observed behavior, the time evolution of the system in the full excitation range studied is modeled by a coherent treatment that provides key insights on the photophysical properties of the molecule.
A generalized many-body expansion and a unified view of fragment-based methods in electronic structure theory
Authors: Richard Ryan M. , Herbert John M.
Published: August 2012

Fragment-based quantum chemistry methods are a promising route towards massively parallel electronic structure calculations in large systems. Unfortunately, the literature on this topic consists of a bewildering array of different methods, with no clear guiding principles to choose amongst them. Here, we introduce a conceptual framework that unifies many of these ostensibly disparate approaches. The common framework is based upon an approximate supersystem energy formula for a collection of intersecting (i.e., overlapping) fragments. This formula generalizes the traditional many-body expansion to cases where the “bodies” (fragments) share some nuclei in common, and reduces to the traditional many-body expansion for non-overlapping fragments. We illustrate how numerous fragment-based methods fit within this framework. Preliminary applications to molecular and ionic clusters suggest that two-body methods in which dimers are constructed from intersecting fragments may be a route to achieve very high accuracy in fragment-based calculations.
Optimized Wang-Landau sampling of lattice polymers: Ground state search and folding thermodynamics of HP model proteins
Authors: Wüst Thomas , Landau David P.
Published: August 2012

Coarse-grained (lattice-) models have a long tradition in aiding efforts to decipher the physical or biological complexity of proteins. Despite the simplicity of these models, however, numerical simulations are often computationally very demanding and the quest for efficient algorithms is as old as the models themselves. Expanding on our previous work [T. Wüst and D. P. Landau, Phys. Rev. Lett. 102, 178101 (2009)]10.1103/PhysRevLett.102.178101, we present a complete picture of a Monte Carlo method based on Wang-Landau sampling in combination with efficient trial moves (pull, bond-rebridging, and pivot moves) which is particularly suited to the study of models such as the hydrophobic-polar (HP) lattice model of protein folding. With this generic and fully blind Monte Carlo procedure, all currently known putative ground states for the most difficult benchmark HP sequences could be found. For most sequences we could also determine the entire energy density of states and, together with suitably designed structural observables, explore the thermodynamics and intricate folding behavior in the virtually inaccessible low-temperature regime. We analyze the differences between random and protein-like heteropolymers for sequence lengths up to 500 residues. Our approach is powerful both in terms of robustness and speed, yet flexible and simple enough for the study of many related problems in protein folding.
Translocation of a heterogeneous polymer
Authors: Mirigian Stephen , Wang Yanbo , Muthukumar Murugappan
Published: August 2012

We present results on the sequence dependence of translocation kinetics for a partially charged heteropolymer moving through a very thin pore using theoretical tools and Langevin dynamics simulational techniques. The chain is composed of two types of monomers of differing frictional interaction with the pore and charge. We present exact analytical expressions for passage probability, mean first passage time, and mean successful passage times for both reflecting/absorbing and absorbing/absorbing boundary conditions, showing rich and unexpected dependence of translocation behavior on charge fraction, distribution along the chain, and electric field configuration. We find excellent qualitative and good quantitative agreement between theoretical and simulation results. Surprisingly, there emerges a threshold charge fraction of a diblock copolymer beyond which the success rate of translocation is independent of charge fraction. Also, the mean successful translocation time of a diblock copolymer displays non-monotonic behavior with increasing length of the charged block; there is an optimum length of the charged block where the mean translocation rate is the slowest; and there can be a substantial range of higher charge fractions which make the translocation slower than even a minimally charged chain. Additionally, we find for a fixed total charge on the chain, finer distribution along the backbone significantly decreases mean translocation time.
Perpendicular-flow, single-wafer atomic layer deposition reactor chamber design for use with in situ diagnostics
Authors: Kimes W. A. , Moore E. F. , Maslar J. E.
Published: August 2012

A description is given of the design and performance of a diagnostic-accessible, perpendicular-flow, single-wafer deposition reactor for use with 50 mm wafers. The reactor chamber design is based on a simple flow tube, with diagnostic access achieved by replacing sections of the reactor chamber wall with recessed diagnostic ports. Reactor chamber performance is evaluated for the purpose of performing optical measurements during atomic layer deposition (ALD). Computational fluid dynamics simulations predict that the when used with windows the diagnostic port design produces minimal perturbations to the gas flow under typical deposition conditions, as compared to a design without diagnostic ports. Temperature measurements of the inside surface of a window installed in a diagnostic port suggest that for reactor chamber operation at 110 °C, under typical deposition conditions, the inside surface window temperature is approximately equal to or greater than the surrounding reactor chamber temperature, thereby minimizing possible species condensation on the window surface. As a consequence of using recessed diagnostic ports, an increase in the amplitude of optical intensity fluctuations was generally observed when performing measurements at elevated chamber temperatures. These intensity fluctuations could be readily reduced by enclosing the optical path to the exterior side of the windows. The performance of two straight-forward methods to reduce these intensity fluctuations is presented. The results outlined above demonstrate that this reactor design can be operated with short gas residence times and with all reactor surfaces at elevated temperatures, making it useful for simulating a wide range of gas flow conditions with relevance to microelectronics-related ALD processes.
Non-local gyrokinetic model of linear ion-temperature-gradient modes
Authors: Moradi S. , Anderson J.
Published: August 2012

The non-local properties of anomalous transport in fusion plasmas are still an elusive topic. In this work, a theory of non-local linear ion-temperature-gradient (ITG) drift modes while retaining non-adiabatic electrons and finite temperature gradients is presented, extending the previous work [S. Moradi et al., Phys. Plasmas 18, 062106 (2011)]. A dispersion relation is derived to quantify the effects on the eigenvalues of the unstable ion temperature gradient modes and non-adiabatic electrons on the order of the fractional velocity operator in the Fokker-Planck equation. By solving this relation for a given eigenvalue, it is shown that as the linear eigenvalues of the modes increase, the order of the fractional velocity derivative deviates from two and the resulting equilibrium probability density distribution of the plasma, i.e., the solution of the Fokker-Planck equation, deviates from a Maxwellian and becomes Lévy distributed. The relative effect of the real frequency of the ITG mode on the deviation of the plasma from Maxwellian is larger than from the growth rate. As was shown previously the resulting Lévy distribution of the plasma may in turn significantly alter the transport as well.
Characteristics of gate-all-around silicon nanowire field effect transistors with asymmetric channel width and source/drain doping concentration
Authors: Baek Chang-Ki , Park Sooyoung , Ko Myung-Dong , Rim Taiuk , Choi Seongwook , Jeong Yoon-Ha
Published: August 2012

We performed 3D simulations to demonstrate structural effects in sub-20 nm gate-all-around silicon nanowire field effect transistors having asymmetric channel width along the channel direction. We analyzed the differences in the electrical and physical properties for various slopes of the channel width in asymmetric silicon nanowire field effect transistors (SNWFETs) and compared them to symmetrical SNWFETs with uniform channel width. In the same manner, the effects of the individual doping concentration at the source and drain also have been investigated. For various structural conditions, the current and switching characteristics are seriously affected. The differences attributed to the doping levels and geometric conditions are due to the electric field and electron density profile.
Note: Aris-Taylor dispersion from single-particle point of view
Authors: Berezhkovskii Alexander M.
Published: August 2012

When a point Brownian particle diffuses in a straight circular tube in the presence of a laminar stationary flow of the liquid, its effective diffusion coefficient along the tube axis increases compared to its value in the absence of flow. The effective diffusion coefficient as a function of the average fluid velocity and the tube radius is given by the Aris-Taylor formula. We give a new derivation of this formula, which is based on consideration of the axial displacement of the particle that moves in the plane normal to the tube axis along a given trajectory. The result is obtained by averaging the displacement and its square over different realizations of the particle trajectory and analyzing the long-time asymptotic behavior of the two moments.
Convenient quantification of methanol concentration detection utilizing an integrated microfluidic chip
Authors: Wang Yao-Nan , Yang Ruey-Jen , Ju Wei-Jhong , Wu Ming-Chang , Fu Lung-Ming
Published: August 2012

A rapid and simple technique is proposed for methanol concentration detection using a PMMA (Polymethyl-Methacrylate) microfluidic chip patterned using a commercially available CO2 laser scriber. In the proposed device, methanol and methanol oxidase (MOX) are injected into a three-dimensional circular chamber and are mixed via a vortex stirring effect. The mixture is heated to prompt the formation of formaldehyde and is flowed into a rectangular chamber, to which fuchsin-sulphurous acid is then added. Finally, the microchip is transferred to a UV spectrophotometer for methanol detection purposes. The experimental results show that a correlation coefficient of R2 = 0.9940 is obtained when plotting the optical density against the methanol concentration for samples and an accuracy as high as 93.1% are compared with the determined by the high quality gas chromatography with concentrations in the range of 2 ∼ 100 ppm. The methanol concentrations of four commercial red wines are successfully detected using the developed device. Overall, the results show that the proposed device provides a rapid and accurate means of detecting the methanol concentration for a variety of applications in the alcoholic beverage inspection and control field.