bluuebunny/crossref_metadata_2025 huggingface dataset:
Response to an aerobic training intervention in young adults depends on ponderal index at birth
Authors: Brutsaert T. D. , Tamvada K. H. , Kiyamu M. , White D. D. , Gage T. B.
Published: April 2012

Poor fetal growth is associated with later-life changes in adult body composition and decrements in muscle strength and morphology. Few studies have investigated the association of poor fetal growth with whole-body exercise. The purpose of this study was to investigate the association of poor fetal growth with the maximal oxygen consumption (VO2max), lactate levels during exercise and the response to aerobic training. Thirty-six college-aged men and women (aged 20.8 ± 0.3 years), born to term (37–42 weeks gestation), were recruited to participate in an 8-week training program. Participants comprised two groups, high ponderal index (HIGHPI) and low ponderal index (LOWPI) (n = 18/group), identified as falling above and below the 10th percentile of the ponderal index (g/cm3)-for-gestational age distribution, respectively. The HIGHPI and LOWPI were matched pair-wise on age, sex, body mass index and pre-study physical activity patterns. The LOWPI and HIGHPI did not differ significantly before training, after training or with a change (Δ) in training VO2max (l/min or ml/min kg/fat-free mass (FFM)). However, LOWPI had significantly lower pre-training lactate levels at similar levels of relative work output (P = 0.016), and significantly smaller decreases in lactate at a fixed level of absolute work after training (P = 0.044). These differences were independent of pre-training aerobic fitness, the change in fitness with training, diet and fuel substrate choice. The lower lactate of untrained LOWPI subjects during exercise could reflect metabolic reprograming due to intrauterine growth restriction, or could be secondary to muscle morphological and/or fiber-type distribution changes that also associate with poor fetal growth.
Numerical simulations of the ionosphere of Mars during a solar flare
Authors: Lollo Anthony , Withers Paul , Fallows Kathryn , Girazian Zachary , Matta Majd , Chamberlin P. C.
Published: April 2012

Electron densities in planetary ionospheres increase substantially during solar flares in response to the increased solar irradiance at soft X‐ray and extreme ultraviolet wavelengths. Here we modify an existing model of the ionosphere of Mars to incorporate time‐dependent solar irradiances and use it to simulate ionospheric conditions during the X14.4 and M7.8 solar flares of 15 and 26 April 2001, respectively. Simulations were validated by comparison to Mars Global Surveyor radio occultation measurements of vertical profiles of ionospheric electron density. Adjustments to the model's representation of the neutral atmosphere were required to adequately reproduce the observations before and during these solar flares. An accurate representation of electron‐impact ionization, an important process in the lower ionosphere of Mars, is required in order to adequately simulate the doubling of electron densities that can occur in the lower ionosphere of Mars during a solar flare. We used the W‐value representation of electron‐impact ionization, in which the number of ion‐electron pairs created per photon absorbed equals the ratio of the difference between photon energy and the ionization potential of carbon dioxide to the W‐value. A range of possible W‐values for Mars have been suggested in the literature, and a value of 28 eV led to the best reproduction of flare‐affected observations. Simulated enhancements in the electron density are largest and persist the longest in the M1 region. We predict that the peak electron density in the M1 region can exceed that of the M2 region for short periods during intense solar flares.
Surface methane emissions from different land use types during various water levels in three major drawdown areas of the Three Gorges Reservoir
Authors: Yang Le , Lu Fei , Wang Xiaoke , Duan Xiaonan , Song Wenzhi , Sun Binfeng , Chen Shuai , Zhang Qianqian , Hou Peiqiang , Zheng Feixiang , Zhang Ye , Zhou Xiaoping , Zhou Yongjuan , Ouyang Zhiyun
Published: April 2012

Methane (CH4) emissions from the drawdown area of the Three Gorges Reservoir (TGR) have not been thoroughly investigated even though the drawdown area encompasses one third of the reservoir surface. In this study, CH4 emissions from different land uses were measured in the TGR drawdown area. The average diffusive CH4 emissions were 2.61, 0.19, 0.18, and 0.12 mg CH4 m−2 h−1 in rice paddies, fallow lands, deforested lands, and croplands, respectively, and were positively related to the duration of the inundated season among the latter three land uses. On average the drawdown areas studied here (except rice paddies) were sources in the inundated season (0.22 ± 0.26 mg CH4 m−2 h−1) and a sink in the drained season (−0.008 ± 0.035 mg CH4 m−2 h−1). The water level was the dominant factor that controlled whether the drawdown area was either inundated or drained, which in turn determined whether the drawdown area was a source or sink of CH4 emissions. The average diffusive CH4 emissions from the fallow lands, croplands, and deforested lands increased as the distance from the dam increased from Zigui (0.10 ± 0.15 mg CH4 m−2 h−1) to Wushan (0.15 ± 0.29 mg CH4 m−2 h−1) to Yunyang (0.24 ± 0.27 mg CH4 m−2 h−1), which could reflect different sediment characteristics and water velocities. The total CH4 emission from the drawdown area was estimated to range from 1033.5 to 1333.9 Mg CH4 yr−1, which would account for 42–54% of the total CH4 emissions from the water surface of TGR.
Looking skyward to study ecosystem carbon dynamics
Authors: Dye Dennis G.
Published: April 2012

Between May and October 2011 the U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program, conducted a field campaign at the ARM Southern Great Plains site in north central Oklahoma to evaluate a new instrument for quantitative image‐based monitoring of sky conditions and solar radiation. The High Dynamic Range All‐Sky Imaging System (HDR‐ASIS) was developed by USGS to support studies of cloud‐ and aerosol‐induced variability in the geometric properties of solar radiation (the sky radiance distribution) and its effects on photosynthesis and uptake of carbon dioxide (CO2) by terrestrial ecosystems. Under a clean, cloudless atmosphere when the Sun is above the horizon, most of the solar radiation reaching an area of the Earth's surface is concentrated in a beam coming directly from the Sun; a relatively small proportion arrives as diffuse radiation from the rest of the sky. Clouds and atmospheric aerosols cause increased scattering of the beam radiation, which increases the proportion of diffuse radiation at the surface.
Partnership proposed for ocean observation
Authors: Rossby T.
Published: April 2012

A report released on 1 March 2012 proposes a formal partnership between the ocean‐observing communities and the global shipping industry for the systematic long‐term study of the ocean water column from surface to depth. According to the report, the rationale for the proposal is that commercial ships on the high seas offer a cost‐effective opportunity to contribute to directly addressing a significant observational deficiency. “The ocean is vastly under observed, particularly below the ocean surface, where satellites cannot measure the ocean's properties,” according to the report, “OceanScope: A proposed partnership between the maritime industries and the ocean observing community to monitor the global ocean water column,” prepared by the Scientific Committee on Oceanic Research/International Association for the Physical Sciences of the Oceans (SCOR/IAPSO) Working Group 133. “Observations below the surface depend on getting platforms (ships, moored buoys, floats, gliders, etc.) to locations far beyond the coasts, which can be expensive,” the report states.
Kelley receives 2011 Hisashi Kuno Award: Citation
Authors: Plank Terry A.
Published: April 2012

Katherine Kelley received the Hisashi Kuno Award at the 2011 AGU Fall Meeting, held 5–9 December in San Francisco, Calif. The award recognizes “accomplishments of junior scientists who make outstanding contributions to the fields of volcanology, geochemistry, and petrology.”
Stream restoration in dynamic fluvial systems: Scientific approaches, analyses, and tools
Authors: Schultz Colin
Published: April 2012

In the United States the average annual investment in river restoration programs is approximately $1 billion. Despite this burgeoning industry, the National Water Quality Inventory, which tracks the health of the nation's rivers, has shown no serious improvement in cumulative river health since the early 1990s. In the AGU monographStream Restoration in Dynamic Fluvial Systems: Scientific Approaches, Analyses, and Tools, editors Andrew Simon, Sean J. Bennett, and Janine M. Castro pull together the latest evidence‐based understanding of stream restoration practices, with an aim of guiding the further development of the field and helping to right its apparently unsuccessful course. In this interview, Eos talks to Sean J. Bennett, University of Buffalo, about the culture, practice, and promise of restoring rivers.
Regional models expect drier, stormier western United States
Authors: Schultz Colin
Published: April 2012

As American southwestern states struggle against ongoing drought and the northwest braces for a projected shift from a snow‐ to a rain‐dominated hydrological system, climate researchers strive to provide precipitation projections that are fine‐grained enough to be of value to municipal water managers. Estimates derived from large general circulation models show that in a warming world, water availability in the western United States will be increasingly dictated by extreme events. However, such large models tend to lack necessary detail for the small‐scale interactions and topographic influences that dominate daily changes in local precipitation. To convert the broad predictions of global models into practical predictions, Dominguez et al. use an ensemble of regional models, set to fit within the projections of general circulation models, to estimate future winter average and extreme precipitation for the western United States.
Statistical technique seeks to reduce climate uncertainty
Authors: Schultz Colin
Published: April 2012

Three measures of the climate system—climate sensitivity, vertical ocean diffusivity, and sulfate aerosol forcing—underpin current understanding of the power of anthropogenic climate change. Climate sensitivity reflects the equilibrium temperature change that would occur given a doubling of atmospheric carbon dioxide, vertical ocean diffusivity affects the rate at which the ocean is able to redistribute heat, and sulfate aerosol forcing describes how anthropogenic sulfate aerosols affect the radiation budget. Other projections rest on these measures, such as changes in weather patterns or precipitation rates, with the derivative predictions sensitive to changes in the more fundamental properties. Given their importance, a key research effort revolves around minimizing the uncertainty in the portrayal of climate sensitivity, ocean diffusivity, and aerosol forcing in climate models. A conventional approach to doing so is to systematically vary climate model parameters in an attempt to minimize the discrepancy between model results and the observational record. The time and financial requirements of running large‐scale climate models, however, reduce this technique's viability. To overcome these barriers, Olson et al. refined an approach to statistically emulate a complex climate model, allowing them to simulate a massive number of model runs at a fraction of the cost.
Active and passive microwave data improve soil moisture estimates
Authors: Balcerak Ernie
Published: April 2012

Assimilating satellite observations from active or passive microwave sensors into models can improve soil moisture estimates, a new study shows. Passive sensors detect radiation emitted naturally from the land surface, while active sensors emit a radiation pulse toward the Earth surface and measure the energy reflected back to the satellite.Draper et al. assimilated soil moisture derived from the active Advanced Scatterometer (ASCAT) and passive Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR‐E) satellite sensors into a land surface model and assessed the resulting soil moisture estimates against in situ observations from 85 sites in the United States and Australia. The researchers found that the active and passive microwave data similarly improved the model's soil moisture estimates. Following the recent failure of AMSR‐E, the new study shows that systems designed to assimilate AMSR‐E soil moisture can switch to ASCAT data without loss of accuracy. Improved soil moisture estimates could be useful for applications such as weather and drought forecasting. (Geophysical Research Letters, doi:10.1029/2011GL050655, 2012)
How did the equatorial ridge on Saturn's moon Iapetus form?
Authors: Balcerak Ernie
Published: April 2012

Saturn's moon Iapetus is one of the most unusual moons in our solar system. Perhaps the most bizarre feature of Iapetus is its equatorial ridge, a 20‐kilometer‐high, 200‐kilometer‐wide mountain range that runs exactly along the equator, circling more than 75% of the moon. No other body in the solar system exhibits such a feature; asDombard et al. show, previous models have been unable to adequately explain how the ridge formed. The authors propose that the ridge formed from an ancient giant impact that produced a subsatellite around Iapetus. Tidal interactions with Iapetus ultimately led to orbital decay, eventually bringing the subsatellite close enough that the same forces tore it apart, forming a debris ring around Iapetus. Material from this debris ring then rained down on Iapetus, the researchers say, creating the mountain ring along the equator. (Journal of Geophysical Research‐Planets, doi:10.1029/2011JE004010, 2012)
Observations of Mercury's northern cusp region with MESSENGER's Magnetometer
Authors: Winslow Reka M. , Johnson Catherine L. , Anderson Brian J. , Korth Haje , Slavin James A. , Purucker Michael E. , Solomon Sean C.
Published: April 2012

The magnetic cusp of a planetary magnetosphere allows solar wind plasma to gain access to the planet's magnetosphere and, for Mercury, the surface. From measurements by the MESSENGER Magnetometer we have characterized the magnetic field in the northern cusp region of Mercury. The first six months of orbital measurements indicate a mean latitudinal extent of the cusp of ∼11°, and a mean local time extent of 4.5 hrs, at spacecraft altitudes. From the average magnetic pressure deficit in the cusp, we estimate that (1.1 ± 0.6) × 1024 protons s−1 bombard the surface over an area of (5.2 ± 1.6) × 1011 m2near the northern cusp. Plasma pressures in the cusp are 40% higher when the interplanetary magnetic field (IMF) is anti‐sunward than when it is sunward. The influence of the IMF direction does not overcome the north‐south asymmetry of Mercury's internal field, and particle flux to the surface near the southern cusp is predicted to be a factor of 4 greater than in the north. The higher particle flux impacting the surface in the south should lead to a greater exospheric source from the south and a higher rate of space weathering than in the area of the northern cusp.
Transcranial Imaging of Functional Cerebral Hemodynamic Changes in Single Blood Vessels using in vivo Photoacoustic Microscopy
Authors: Liao Lun-De , Lin Chin-Teng , Shih Yen-Yu I , Duong Timothy Q , Lai Hsin-Yi , Wang Po-Hsun , Wu Robby , Tsang Siny , Chang Jyh-Yeong , Li Meng-Lin , Chen You-Yin
Published: April 2012

Optical imaging of changes in total hemoglobin concentration ( HbT), cerebral blood volume ( CBV), and hemoglobin oxygen saturation ( SO 2) provides a means to investigate brain hemodynamic regulation. However, high-resolution transcranial imaging remains challenging. In this study, we applied a novel functional photoacoustic microscopy technique to probe the responses of single cortical vessels to left forepaw electrical stimulation in mice with intact skulls. Functional changes in HbT, CBV, and SO 2 in the superior sagittal sinus and different-sized arterioles from the anterior cerebral artery system were bilaterally imaged with unambiguous 36 × 65- μm2 spatial resolution. In addition, an early decrease of SO 2 in single blood vessels during activation (i.e., ‘the initial dip’) was observed. Our results indicate that the initial dip occurred specifically in small arterioles of activated regions but not in large veins. This technique complements other existing imaging approaches for the investigation of the hemodynamic responses in single cerebral blood vessels.
The Unfolded Protein Response and its potential role in Huntington's disease
Authors: Kalathur Ravi , Ayasolla Kamesh , Futschik Matthias
Published: April 2012

Huntington's disease (HD) is a progressive, neurodegenerative disease with fatal outcome. Although the disease-causing gene (huntingtin) has been known for some time, the exact cause of neuronal cell death is still unknown. One potential mechanism contributing to the massive loss of neurons in the brain of HD patients might be the unfolded protein response (UPR), which is activated by accumulation of misfolded proteins in the endoplasmatic reticulum (ER). As an adaptive response to counter-balance accumulation of un- or misfolded proteins, the UPR upregulates transcription of chaperones, temporarily attenuates new translation, and activates protein degradation via the proteasome. However, it is known that persistent ER stress and activated UPR can cause cell death by triggering of apoptosis. Nevertheless, the evidence linking UPR with HD progression remains inconclusive. Here, we present first analyses of UPR activation during HD based on available expression data. To elucidate the potential role of UPR as a disease-relevant process, we examine its connection to cell death and inflammatory processes. Due to the complexity of these molecular mechanisms, a systems biology approach was pursued.
Language Use in Social Interactions of School-Age Children With Language Impairments: An Evidence-Based Systematic Review of Treatment
Authors: Gerber Sima , Brice Alejandro , Capone Nina , Fujiki Martin , Timler Geralyn
Published: April 2012

Introduction

Pragmatic models were first applied to the treatment of children with language impairment in the late 1970s. Since that time, the study of language use has had considerable impact on language assessment and treatment. Despite the need to address pragmatic language skills clinically, there has been no systematic examination of the efficacy of treatments developed for this purpose.

Method

In accordance with the evidence-based practice policy agenda, the American Speech-Language-Hearing Association (ASHA) convened an ad hoc committee on language use in social interactions in school-age children. The committee’s charge was to develop an evidence-based systematic review of treatment for disorders of language use in social interactions. This charge was conducted in collaboration with ASHA’s National Center for Evidence-Based Practice in Communication Disorders.

Results

This systematic review provided preliminary support for the feasibility of various treatment procedures addressing social communication behaviors. Gains were reported in topic management skills, narrative production, and repairs of inadequate or ambiguous comments.

Conclusion

Because further investigation of these treatments is warranted, the committee is unable to make empirically supported recommendations for changes in standard clinical practice based solely on this review. More research is needed to examine the feasibility of interventions that focus on children’s language use.
Speech-Language Pathologist Job Satisfaction in School Versus Medical Settings
Authors: Kalkhoff Nicole L. , Collins Dana R.
Published: April 2012

Purpose

The goal of this study was to determine if job satisfaction differs between speech-language pathologists (SLPs) working in school settings and SLPs working in medical settings.

Method

The Job Satisfaction Survey (JSS) by Spector (1997) was sent via electronic mail to 250 SLPs in each of the 2 settings. Job satisfaction scores were computed from subscale category ratings and were compared between the 2 settings. Subscale category ratings for pay, promotion, supervision, benefits, contingent rewards, operating conditions, coworkers, nature of work, and communication were analyzed for differences between and within settings. Age, caseload size, and years-at-position were analyzed by linear regression to determine whether these factors might predict SLPs' job satisfaction.

Results

The survey had a response rate of 19.6% (
N
= 98 participants). Although SLPs in both settings were generally satisfied with their jobs, SLPs in medical settings had significantly higher total job satisfaction scores. Respondents from both settings had similar satisfaction ratings for subscale categories, with nature of work receiving the highest rating and operating conditions and promotion the lowest. Results of the linear regression analysis for age, caseload size, and years-at-position were not significant.

Conclusion

Further research should evaluate important aspects of job satisfaction in both settings, especially nature of work operating conditions, and promotion.
Linguistic Pattern Analysis of Misspellings of Typically Developing Writers in Grades 1–9
Authors: Bahr Ruth Huntley , Silliman Elaine R. , Berninger Virginia W. , Dow Michael
Published: April 2012

Purpose

A mixed-methods approach, evaluating triple word-form theory, was used to describe linguistic patterns of misspellings.

Method

Spelling errors were taken from narrative and expository writing samples provided by 888 typically developing students in Grades 1–9. Errors were coded by category (phonological, orthographic, and morphological) and specific linguistic feature affected. Grade-level effects were analyzed with trend analysis. Qualitative analyses determined frequent error types and how use of specific linguistic features varied across grades.

Results

Phonological, orthographic, and morphological errors were noted across all grades, but orthographic errors predominated. Linear trends revealed developmental shifts in error proportions for the orthographic and morphological categories between Grades 4 and 5. Similar error types were noted across age groups, but the nature of linguistic feature error changed with age.

Conclusions

Triple word-form theory was supported. By Grade 1, orthographic errors predominated, and phonological and morphological error patterns were evident. Morphological errors increased in relative frequency in older students, probably due to a combination of word-formation issues and vocabulary growth. These patterns suggest that normal spelling development reflects nonlinear growth and that it takes a long time to develop a robust orthographic lexicon that coordinates phonology, orthography, and morphology and supports word-specific, conventional spelling.
Ground and low-lying excited states of propadienylidene (H2C=C=C:) obtained by negative ion photoelectron spectroscopy
Authors: Stanton John F. , Garand Etienne , Kim Jongjin , Yacovitch Tara I. , Hock Christian , Case Amanda S. , Miller Elisa M. , Lu Yu-Ju , Vogelhuber Kristen M. , Wren Scott W. , Ichino Takatoshi , Maier John P. , McMahon Robert J. , Osborn David L. , Neumark Daniel M. , Lineberger W. Carl
Published: April 2012

A joint experimental-theoretical study has been carried out on electronic states of propadienylidene (H2CCC), using results from negative-ion photoelectron spectroscopy. In addition to the previously characterized \documentclass[12pt]{minimal}\begin{document}${\tilde{X}}^1A_1$\end{document}X̃1A1 electronic state, spectroscopic features are observed that belong to five additional states: the low-lying \documentclass[12pt]{minimal}\begin{document}${\tilde{a}}^3B_1$\end{document}ã3B1 and \documentclass[12pt]{minimal}\begin{document}${\tilde{b}}^3A_2$\end{document}b̃3A2 states, as well as two excited singlets, \documentclass[12pt]{minimal}\begin{document}${\tilde{A}}^1A_2$\end{document}Ã1A2 and \documentclass[12pt]{minimal}\begin{document}${\tilde{B}}^1B_1$\end{document}B̃1B1, and a higher-lying triplet, \documentclass[12pt]{minimal}\begin{document}${\tilde{c}}^3A_1$\end{document}c̃3A1. Term energies (T0, in cm−1) for the excited states obtained from the data are: 10 354±11 (\documentclass[12pt]{minimal}\begin{document}${\tilde{a}}^3B_1$\end{document}ã3B1); 11 950±30 (\documentclass[12pt]{minimal}\begin{document}${\tilde{b}}^3A_2$\end{document}b̃3A2); 20 943±11 (\documentclass[12pt]{minimal}\begin{document}${\tilde{c}}^3A_1$\end{document}c̃3A1); and 13 677±11 (\documentclass[12pt]{minimal}\begin{document}${\tilde{A}}^1A_2$\end{document}Ã1A2). Strong vibronic coupling affects the \documentclass[12pt]{minimal}\begin{document}${\tilde{A}}^1A_2$\end{document}Ã1A2 and \documentclass[12pt]{minimal}\begin{document}${\tilde{B}}^1B_1$\end{document}B̃1B1 states as well as \documentclass[12pt]{minimal}\begin{document}${\tilde{a}}^3B_1$\end{document}ã3B1 and \documentclass[12pt]{minimal}\begin{document}${\tilde{b}}^3A_2$\end{document}b̃3A2 and has profound effects on the spectrum. As a result, only a weak, broadened band is observed in the energy region where the origin of the \documentclass[12pt]{minimal}\begin{document}${\tilde{B}}^1B_1$\end{document}B̃1B1 state is expected. The assignments here are supported by high-level coupled-cluster calculations and spectral simulations based on a vibronic coupling Hamiltonian. A result of astrophysical interest is that the present study supports the idea that a broad absorption band found at 5450 Å by cavity ringdown spectroscopy (and coincident with a diffuse interstellar band) is carried by the \documentclass[12pt]{minimal}\begin{document}${\tilde{B}}^1B_1$\end{document}B̃1B1 state of H2CCC.
Elastic cross sections for electron scattering from GeF4: Predominance of atomic-F in the high-energy collision dynamics
Authors: Kato H. , Suga A. , Hoshino M. , Blanco F. , García G. , Limão-Vieira P. , Brunger M. J. , Tanaka H.
Published: April 2012

We report absolute differential cross sections (DCSs) for elastic electron scattering from GeF4. The incident electron energy range was 3–200 eV, while the scattered electron angular range was typically 15°–150°. In addition, corresponding independent atom model (IAM) calculations, within the screened additivity rule (SCAR) formulation, were also performed. Those results, particularly for electron energies above about 10 eV, were found to be in good quantitative agreement with the present experimental data. Furthermore, we compare our GeF4 elastic DCSs to similar data for scattering from CF4 and SiF4. All these three species possess Td symmetry, and at each specific energy considered above about 50 eV their DCSs are observed to be almost identical. These indistinguishable features suggest that high-energy elastic scattering from these targets is virtually dominated by the atomic-F species of the molecules. Finally, estimates for the measured GeF4 elastic integral cross sections are derived and compared to our IAM-SCAR computations and with independent total cross section values.
Nanopatterning of mica surface under low energy ion beam sputtering
Authors: Metya A. , Ghose D. , Mollick S. A. , Majumdar A.
Published: April 2012

Irradiation of crystalline muscovite mica samples by 500 eV Ar+ ions at different incident angles can induce significant surface morphological variations. A periodic ripple pattern of nano-dimensions forms in the angle window 47°-70°. On the other hand, tilted conical protrusions develop on the surface at grazing incidence angles around 80°. From the derivative of the topographic images the distribution of the side-facet slopes in the ion incidence plane are measured, which is found to be strongly related to the pattern morphology. Additionally, it has been shown that, for the ripple structures, the base angles can be tuned by changing the ion fluence. An asymmetric sawtooth profile of the ripples obtained at low fluence is transformed to a symmetrical triangular profile at high fluence. As the slopes are found to be small, the pattern formation is not provoked by the gradient-dependent erosion mechanism rather it is the general effect of the curvature-dependent sputtering phenomena.
Optical and electrical characteristics of asymmetric nanowire solar cells
Authors: Ko Myung-Dong , Baek Chang-Ki , Rim Taiuk , Park Sooyoung , Jeong Yoon-Ha
Published: April 2012

We propose an asymmetric radial structure developed via simulation that improves the optical and electrical characteristics of silicon nanowire (SiNW) solar cells. This nanostructure is designed by shrinking the bottom core diameter and holding the top core diameter fixed in the SiNW, which results in a total reflection of the incident light in the outer wall of the shell due to the difference in the refractive index. The reflection enhances light trapping and concentration, which results in a 10 times higher optical generation rate and greater optical absorption in the high energy regime as compared with the fundamental symmetric radial structure. Further, we found that the efficiency is increased by over 10% when the bottom core diameter is decreased. The proposed structure has great potential to effectively improve the efficiency in concert with optimizing the design parameters.
A 10 tesla table-top controlled waveform magnet
Authors: Roy Choudhury Aditya N. , Venkataraman V.
Published: April 2012

Controlled waveform magnets (CWMs) are a class of pulsed magnets whose pulse shape with time can be programmed by the user. With a CWM, the user gains control not only over the magnitude of the field but also over its rate of change. In this work we present a table-top CWM, driven by a capacitor bank, capable of producing virtually any user-shaped magnetic field waveform up to 10 tesla. Insulated gate bipolar transistor chips have been paralleled to form the high current switch and paralleled chips of SiC Schottky diodes form the crowbar diode module. Sample controlled waveforms including flat-tops up to 10 tesla and some triangular magnetic field pulses have been successfully generated for 10–20 ms with a ripple <1%.
Revisiting the phase diagram of hard ellipsoids
Authors: Odriozola Gerardo
Published: April 2012

In this work, the well-known Frenkel-Mulder phase diagram of hard ellipsoids of revolution [D. Frenkel and B. M. Mulder, Mol. Phys. 55, 1171 (1985)10.1080/00268978500101971] is revisited by means of replica exchange Monte Carlo simulations. The method provides good sampling of dense systems and so, solid phases can be accessed without the need of imposing a given structure. At high densities, we found plastic solids and fcc-like crystals for semi-spherical ellipsoids (prolates and oblates), and SM2 structures [P. Pfleiderer and T. Schilling, Phys. Rev. E 75, 020402 (2007)] for x : 1-prolates and 1 : x-oblates with x ≥ 3. The revised fluid-crystal and isotropic-nematic transitions reasonably agree with those presented in the Frenkel-Mulder diagram. An interesting result is that, for small system sizes (100 particles), we obtained 2:1- and 1.5:1-prolate equations of state without transitions, while some order is developed at large densities. Furthermore, the symmetric oblate cases are also reluctant to form ordered phases.
Massive spalling of Cu-Zn and Cu-Al intermetallic compounds at the interface between solders and Cu substrate during liquid state reaction
Authors: Kotadia H. R. , Panneerselvam A. , Mokhtari O. , Green M. A. , Mannan S. H.
Published: April 2012

The interfacial intermetallic compound (IMC) formation between Cu substrate and Sn-3.8Ag-0.7Cu-X (wt.%) solder alloys has been studied, where X consists of 0–5% Zn or 0–2% Al. The study has focused on the effect of solder volume as well as the Zn or Al concentration. With low solder volume, when the Zn and Al concentrations in the solder are also low, the initial Cu-Zn and Al-Cu IMC layers, which form at the solder/substrate interface, are not stable and spall off, displaced by a Cu6Sn5 IMC layer. As the total Zn or Al content in the system increases by increasing solder volume, stable CuZn or Al2Cu IMCs form on the substrate and are not displaced. Increasing concentration of Zn has a similar effect of stabilizing the Cu-Zn IMC layer and also of forming a stable Cu5Zn8 layer, but increasing Al concentration alone does not prevent spalling of Al2Cu. These results are explained using a combination of thermodynamic- and kinetics-based arguments.
Surface polar states and pyroelectricity in ferroelastics induced by flexo-roto field
Authors: Morozovska A. N. , Eliseev E. A. , Kalinin S. V. , Qing Chen Long , Gopalan Venkatraman
Published: April 2012

Theoretical analysis based on the Landau-Ginzburg-Devonshire theory is used to show that the joint action of flexoelectric effect and rotostriction leads to a large spontaneous in-plane polarization (∼1-5 μC/cm2) and pyroelectric coefficient (∼10−3 C/m2K) in the vicinity of surfaces of otherwise non-ferroelectric ferroelastics, such as SrTiO3, with static octahedral rotations. The origin of the improper polarization and pyroelectricity is an electric field we name flexo-roto field whose strength is proportional to the convolution of the flexoelectric and rotostriction tensors with octahedral tilts and their gradients. Flexo-roto field should exist at surfaces and interfaces in all structures with static octahedral rotations, and thus, it can induce surface polar states and pyroelectricity in a large class of otherwise nonpolar materials.
Surface area enhancement of microcantilevers by femto-second laser irradiation
Authors: Kumar A. , Rajauria S. , Huo H. , Ozsun O. , Rykaczewski K. , Kumar J. , Ekinci K. L.
Published: April 2012

A dry single-step process for enhancing the surface area of a silicon microcantilever is described. In this process, a flat microcantilever is irradiated with ∼100-femto-second-long laser pulses. The silicon surface melts and rapidly cools, resulting in the formation of nanoscale pillars. The shape and size of these nanostructures can be tuned by changing the energy of the pulses. Resonance measurements on surface-enhanced microcantilevers show that the irradiation process reduces the stiffness and the resonance frequency of the cantilevers. Fluidic dissipation measurements provide an estimate for the surface area increase. Both the enhanced surfaces and the fluidic characteristics of these microcantilevers may be useful in bio-chemical sensing applications.
Automated markerless full field hard x-ray microscopic tomography at sub-50 nm 3-dimension spatial resolution
Authors: Wang Jun , Karen Chen Yu-chen , Yuan Qingxi , Tkachuk Andrei , Erdonmez Can , Hornberger Benjamin , Feser Michael
Published: April 2012

A full field transmission x-ray microscope (TXM) has been developed and commissioned at the National Synchrotron Light Source at Brookhaven National Laboratory. The capabilities we developed in auto-tomography, local tomography, and spectroscopic imaging that overcome many of the limitations and difficulties in existing transmission x-ray microscopes are described and experimentally demonstrated. Sub-50 nm resolution in 3-dimension (3D) with markerless automated tomography has been achieved. These capabilities open up scientific opportunities in many research fields.
Air Pollution and Business Political Influence in Fifteen OECD Countries
Authors: Bernhagen Patrick
Published: April 2012

In this paper I examine the political influence of business in the context of environmental politics by comparing the explanatory role of three distinct sources of business power: political organization, a structurally privileged position in politics, and informational advantages. Using data on fifteen OECD countries between 1981 and 1999, the analysis shows that business organizational strength and information asymmetry in government–business relations are important determinants of observed differences in air pollution across countries and over time. By contrast, there is no support for the claim that the structural dominance of business constrains political efforts to improve air quality. By analyzing the role of asymmetric information and systems of interest intermediation simultaneously, the paper contributes to our understanding of the causal mechanisms that link corporatism to environmental performance.
Immigration and the Economic Health of Canadian Cities
Authors: Reese Laura A
Published: April 2012

This research explores relationships between diversity of local populations and economic well-being: specifically, the connections between foreign-born populations, other measures of community diversity, and local economic health. Using data from the population of mid-sized Canadian cities, I conclude that there is a significant relationship between immigration and health. Several other aspects of diversity—language, visible minority status, and religion—are also related to economic health, but only the correlation with foreign born remains significant in multiple regression. The extent that population growth is dependent on immigration and the clear dispersion of immigrants to mid-sized communities in Canada is an argument for greater attention to public policies that facilitate settlement both on humanitarian grounds and to foster local economic development.
Assessing the Relative Health Care Spending Needs of the UK's Devolved Territories: A Scottish Perspective
Authors: Ball Rob , King David , Eiser David
Published: April 2012

This paper applies Scotland's health allocation formula to Primary Care Trusts (PCTs) in England, Health Boards in Wales, and Health and Social Care Trusts in Northern Ireland in order to assess the relative health care expenditure needs of the countries. According to the Scottish formula, England's per capita health care expenditure need is around 10% lower than Scotland's, while Wales' per capita expenditure need is around 2% lower than Scotland's, and Northern Ireland's is around 7% lower than Scotland's. Scotland's relative expenditure need over England is largely a function of higher rates of mortality and long-term illness, rather than its relative sparsity. Northern Ireland's relatively lower need is largely due to it having a relatively young population. We also compare the results of Scotland's allocation formula with the equivalent English formula and find that the two approaches differ in their view of what constitutes an equitable distribution of resources between PCTs.
Citizen Control and the Efficiency of Local Public Services
Authors: Bosch Núria , Espasa Marta , Mora Toni
Published: April 2012

It is generally accepted that fiscal decentralization increases citizen control over politicians, fostering accountability and increasing efficiency. We identify the socioeconomic characteristics of citizens that increase their control over local policy makers and thus generate greater efficiency in a decentralized context. We also highlight the fiscal characteristics that influence this control and efficiency. The study examines a sample of Spanish municipalities, applying a methodology based on the conventional procedure of two-stage estimation. The results provide a certain amount of empirical evidence that suggests that the strong presence of retailers and retired people favours citizen control, which fosters accountability and efficiency. A factor that facilitates this control, and therefore greater efficiency, is the presence of low opportunity costs for obtaining information regarding local public service management. We also demonstrate that a high level of taxation does not lead to greater control by citizens and that transfers generate the ‘flypaper effect’.
Corrigendum to: Annual secondary production of two estuarine mysid species (Mysidacea : Mysidae) inhabiting an intermittently closed estuary, south-eastern New Zealand
Authors: Lill Adrian W. T. , Closs Gerard P. , Savage Candida , Schallenberg Marc
Published: April 2012

Estimates of secondary production are essential to understanding how communities function. Estimates of secondary production for key species such as mysids are scarce, especially in estuarine environments. There are no estimates for mysid production in intermittently closed estuaries in the world, and no estimates for endemic New Zealand mysids. The current study presents length?mass models for two mysid species (Tenagomysis chiltoni Tattersall, 1923 and T. novae-zealandiae Thomson, 1900) from the south-eastern coast of the South Island, New Zealand. Kaikorai Lagoon, a small intermittently closed estuary, supported a large average annual biomass of T. novae-zealandiae (861.77 mg m?2) and T. chiltoni (971.90 mg m?2). The Hynes average-cohort method was used with length?mass models to estimate the annual production of breeding populations of T. chiltoni and T. novae-zealandiae collected over a year in parts of the Kaikorai Lagoon. Compared with similar temperate ecosystems worldwide, the studied ecosystem indicated high annual production (11 328.8 mg m?2 year?1 and 6585.2 mg m?2 year?1) and turnover rates (P : B) (13.16 and 6.78) for T. novae-zealandiae and T. chiltoni, respectively. High annual secondary production may be due to relatively stable hydrological and food conditions found in intermittently closed estuaries, leading to dense stable populations that are maintained through much of the year.
Surveillance System of Hemodialysis-Associated Infections in a Pediatric Unit
Authors: Sucupira Carolina , Abramczyk Marcelo Luiz , Carvalhaes João Tomas de Abreu , de Moraes-Pinto Maria Isabel
Published: April 2012

The bloodstream infection surveillance system proposed by the Centers for Disease Control and Prevention (CDC) was prospectively conducted in a pediatric hemodialysis unit. Thirty patients were included; 73% had a catheter for vascular access at enrollment. Vascular access infection rate was 21.1 per 100 patient-months, well above those observed in adult patient surveys.Staphylococcus aureuswas most frequently isolated (23%).
Improved Risk Adjustment in Public Reporting: Coronary Artery Bypass Graft Surgical Site Infections
Authors: Berríos-Torres Sandra I. , Mu Yi , Edwards Jonathan R. , Horan Teresa C. , Fridkin Scott K.
Published: April 2012

Objective.

The objective was to develop a new National Healthcare Safety Network (NHSN) risk model for sternal, deep incisional, and organ/space (complex) surgical site infections (SSIs) following coronary artery bypass graft (CABG) procedures, detected on admission and readmission, consistent with public reporting requirements.

Patients and Setting.

A total of 133,503 CABG procedures with 4,008 associated complex SSIs reported by 293 NHSN hospitals in the United States.

Methods.

CABG procedures performed from January 1, 2006, through December 31, 2008, were analyzed. Potential SSI risk factors were identified by univariate analysis. Multivariate analysis with forward stepwise logistic regression modeling was used to develop the new model. The c-index was used to compare the predictive power of the new and NHSN risk index models.

Results.

Multivariate analysis independent risk factors included ASA score, procedure duration, female gender, age, and medical school affiliation. The new risk model has significantly improved predictive performance over the NHSN risk index (c-index, 0.62 and 0.56, respectively).

Conclusions.

Traditionally, the NHSN surveillance system has used a risk index to provide procedure-specific risk-stratified SSI rates to hospitals. A new CABG sternal, complex SSI risk model developed by multivariate analysis has improved predictive performance over the traditional NHSN risk index and is being considered for endorsement as a measure for public reporting.
Cost-Effectiveness Analysis of Active Surveillance Screening for Methicillin-ResistantStaphylococcus aureusin an Academic Hospital Setting
Authors: Kang JaHyun , Mandsager Paul , Biddle Andrea K. , Weber David J.
Published: April 2012

Objective.

To evaluate the cost-effectiveness of 3 alternative active screening strategies for methicillin-resistantStaphylococcus aureus(MRSA): universal surveillance screening for all hospital admissions, targeted surveillance screening for intensive care unit admissions, and no surveillance screening.

Design.

Cost-effectiveness analysis using decision modeling.

Methods.

Cost-effectiveness was evaluated from the perspective of an 800-bed academic hospital with 40,000 annual admissions over the time horizon of a hospitalization. All input probabilities, costs, and outcome data were obtained through a comprehensive literature review. Effectiveness outcome was MRSA healthcare-associated infections (HAIs). One-way and probabilistic sensitivity analyses were conducted.

Results.

In the base case, targeted surveillance screening was a dominant strategy (ie, was associated with lower costs and resulted in better outcomes) for preventing MRSA HAL Universal surveillance screening was associated with an incremental cost-effectiveness ratio of $14,955 per MRSA HAL In one-way sensitivity analysis, targeted surveillance screening was a dominant strategy across most parameter ranges. Probabilistic sensitivity analysis also demonstrated that targeted surveillance screening was the most cost-effective strategy when willingness to pay to prevent a case of MRSA HAI was less than $71,300.

Conclusion.

Targeted active surveillance screening for MRSA is the most cost-effective screening strategy in an academic hospital setting. Additional studies that are based on actual hospital data are needed to validate this model. However, the model supports current recommendations to use active surveillance to detect MRSA.
Comparison of the Microbiological Efficacy of Hydrogen Peroxide Vapor and Ultraviolet Light Processes for Room Decontamination
Authors: Havill Nancy L. , Moore Brent A. , Boyce John M.
Published: April 2012

Objective.

To compare the microbiological efficacy of hydrogen peroxide vapor (HPV) and ultraviolet radiation (UVC) for room decontamination.

Design.

Prospective observational study.

Setting.

500-bed teaching hospital.

Methods.

HPV and UVC processes were performed in 15 patient rooms. Five high-touch sites were sampled before and after the processes and aerobic colony counts (ACCs) were determined. Carrier disks with ~106Clostridium difficile (CD) spores and biological indicators (BIs) with 104 and 106Geobacillus stearothermophilus spores were placed in 5 sites before decontamination. After decontamination, CD log reductions were determined and BIs were recorded as growth or no growth.

Results.

93% of ACC samples that had growth before HPV did not have growth after HPV, whereas 52% of sites that had growth before UVC did not have growth after UVC (P < .0001). The mean CD log reduction was >6 for HPV and ~2 for UVC. After HPV 100% of the 104 BIs did not grow, and 22% did not grow after UVC, with a range of 7%–53% for the 5 sites. For the 106 BIs, 99% did not grow after HPV and 0% did not grow after UVC. Sites out of direct line of sight were significantly more likely to show growth after UVC than after HPV. Mean cycle time was 153 (range, 140–177) min for HPV and 73 (range, 39–100) min for UVC (P < .0001).

Conclusion.

Both HPV and UVC reduce bacterial contamination, including spores, in patient rooms, but HPV is significantly more effective. UVC is significantly less effective for sites that are out of direct line of sight.
Making Gerontocracy Work: Population Aging and the Generosity of Public Long‐term Care
Authors: Ellegård Lina Maria
Published: April 2012

This paper examines how the aging population affects the generosity of public long‐term care (LTC) in Sweden. Theoretically, aging has a direct effect on LTC policy because the elderly become a more important voter group. However, concerns for other citizens may dampen the political importance of the elderly. Fixed effects regressions on municipality‐level panel data for 1999‐2007 suggest that LTC generosity slightly decreases in response to an aging population. In particular, a smaller share of the elderly become entitled to LTC.