bluuebunny/crossref_metadata_2025 huggingface dataset:
Interpersonal behaviour in one-to-one instrumental lessons: An observational analysis
Authors: Creech Andrea
Published: April 2012

This paper explores patterns of interpersonal behaviour amongst teachers and pupils during one-to-one instrumental lessons. It was hypothesised that these patterns might differ in systematic ways, according to an existing model of six interaction ‘types’ developed within a systems theory perspective and based on measures of interpersonal control and responsiveness. Eleven violin teachers and their pupils aged 10–16 were observed. Digital recordings of 23 one-to-one lessons were analysed using the overarching categories of teacher talk, teacher questioning, scaffolding, pupil talk and pupil playing. Behaviour style was found to correspond with the model of interpersonal interaction in instrumental teaching. Highly directive teachers were found to engage most often in scaffolding, while the most responsive teachers allowed space for the pupil voice to be heard and provided more feedback that was attributed to specific strategies or effort. These findings suggest that teachers and pupils may become entrenched in fixed patterns of interaction behaviour that potentially place constraints on teaching and learning outcomes. The implications for practice lie in teachers’ awareness and reflections on their own interaction behaviours. Being cognisant of fixed patterns of behaviour, teachers may choose to re-frame their style of interaction, thus effecting positive changes in teaching and learning.
Age, marital status and changes in dietary habits in later life: a 21-year follow-up among Finnish women
Authors: Haapala Irja , Prättälä Ritva , Patja Kristiina , Männikkö Reija , Hassinen Maija , Komulainen Pirjo , Rauramaa Rainer
Published: April 2012

Objective

To examine 21-year longitudinal changes in dietary habits and their associations with age and marital status among women aged 50–60 years at baseline.

Design

Prospective, longitudinal study of a cohort in the FINMONICA population-based risk factor survey with clinical assessments in 1982, 1992 and 2003. Dietary habits were assessed via self-reported consumption of foods typically contributing to SFA, cholesterol and sugar intakes in the Finnish diet. A dietary risk score based upon five items was used.

Setting

Kuopio region, Finland.

Subjects

Complete data from all three assessments for 103 women of the original cohort of 299 were included for two age groups: 50–54 and 55–60 years at baseline.

Results

Dietary habits improved between 1982 and 1992 and showed continued but less pronounced improvement between 1992 and 2003: within the younger age group, 78 % of the women reduced the number of dietary risk points from the 1982 to 2003 scores, whereas 3 % increased them and 19 % reported no change. In the older age group these percentages were 61 %, 23 % and 16 %, respectively. Women who remained married showed a steadier decline in dietary risk points than single women or women who were widows at the beginning of the follow-up.

Conclusions

Older women make positive changes to their dietary habits but the consistency of these changes may be affected by the ageing process, marital status and changes in the latter.
Management of neuroendocrine small cell carcinoma of cervix-a single centre retrospective study
Authors: Mcgivern Ursula , Clarke Jacqueline , Drake Anne , McGluggage Glenn , McAleese Jonathan
Published: April 2012

Purpose: To determine disease-free and overall survival of neuroendocrine small cell cancer of cervix treated at the Northern Ireland Cancer centre between 1999 and 2010.

Materials and methods: A retrospective review of all patients diagnosed and treated with neuroendocrine small cell cancer of cervix in Northern Ireland. Details of treatment modality including chemotherapy, radiotherapy and surgery were recorded.

Results: Fifteen patients diagnosed with neuroendocrine small cell carcinoma (NSCC) of cervix were identified between 1999 and 2010, twelve with disease localised to the pelvis and three with metastatic disease. Three-year overall survival for all patients was 65% and disease-free survival was 45% for all patients. In patients with pelvic confined disease 3-year overall survival was 79% and disease-free survival was 57%. Median disease-free and overall survival was 30 and 39.6 months respectively. These survival rates compare very favourably to those reported in the literature. Stage of disease at diagnosis was the main determinant of survival.

Conclusion: Local control and survival can be achieved in NSCC of patients with a combination of irradiation and platinum-based chemotherapy. Stage of disease determines outcomes.
On the S-fundamental group scheme. II
Authors: Langer Adrian
Published: April 2012

The S-fundamental group scheme is the group scheme corresponding to the Tannaka category of numerically flat vector bundles. We use determinant line bundles to prove that the S-fundamental group of a product of two complete varieties is a product of their S-fundamental groups as conjectured by Mehta and the author. We also compute the abelian part of the S-fundamental group scheme and the S-fundamental group scheme of an abelian variety or a variety with trivial étale fundamental group.
The algebraic numbers definable in various exponential fields
Authors: Kirby Jonathan , Macintyre Angus , Onshuus Alf
Published: April 2012

We prove the following theorems. Theorem 1: for any E-field with cyclic kernel, in particular ℂ or the Zilber fields, all real abelian algebraic numbers are pointwise definable. Theorem 2: for the Zilber fields, the only pointwise definable algebraic numbers are the real abelian numbers.
Who benefits from health services in South Africa?
Authors: Ataguba John Ele-Ojo , McIntyre Di
Published: April 2012

South Africa is considering major health service restructuring to move towards a universal system. This calls for understanding the challenges in the existing health system. The paper, therefore, comprehensively evaluates an aspect of current health system performance – the benefit incidence of health services. It seeks to understand how the benefits from using health services in South Africa are currently distributed across socio-economic groups. Using a nationally representative household survey, results show that lower socio-economic groups benefit less than their richer counterparts from both public and private sector health services, and that the distribution of service benefits is not in line with their need for care.
Intense dayside Joule heating during the 5 April 2010 geomagnetic storm recovery phase observed by AMIE and AMPERE
Authors: Wilder F. D. , Crowley G. , Anderson B. J. , Richmond A. D.
Published: April 2012

When the interplanetary magnetic field (IMF) is northward, dawnward, or duskward, magnetic merging between the IMF and the geomagnetic field occurs near the cusp of the magnetosphere. While these periods are usually considered “quiet,” they can lead to intense, but highly localized, energy deposition into the dayside ionosphere. We identify such an occurrence during a series of two geomagnetic storms on 5 April 2010. Using data from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) for the first time as an input to the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) algorithm, we show that during the recovery phase of the first storm there is intense ionospheric Joule heating in the dayside polar regions. This is associated with an intense field‐aligned current pair near the noon meridian that is associated with northward IMF and a strong IMF By component. AMIE outputs are used to drive the thermosphere‐ionosphere‐mesosphere electrodynamics general circulation model to demonstrate that the intense levels of Joule heating can lead to anomalous thermospheric density enhancements and traveling disturbances.
The influence of Langmuir turbulence on the scaling for the dissipation rate in the oceanic boundary layer
Authors: Teixeira Miguel A. C.
Published: April 2012

A model for estimating the turbulent kinetic energy dissipation rate in the oceanic boundary layer, based on insights from rapid‐distortion theory, is presented and tested. This model provides a possible explanation for the very high dissipation levels found by numerous authors near the surface. It is conceived that turbulence, injected into the water by breaking waves, is subsequently amplified due to its distortion by the mean shear of the wind‐induced current and straining by the Stokes drift of surface waves. The partition of the turbulent shear stress into a shear‐induced part and a wave‐induced part is taken into account. In this picture, dissipation enhancement results from the same mechanism responsible for Langmuir circulations. Apart from a dimensionless depth and an eddy turn‐over time, the dimensionless dissipation rate depends on the wave slope and wave age, which may be encapsulated in the turbulent Langmuir numberLat. For large Lat, or any Lat but large depth, the dissipation rate tends to the usual surface layer scaling, whereas when Lat is small, it is strongly enhanced near the surface, growing asymptotically as ε ∝ Lat−2 when Lat → 0. Results from this model are compared with observations from the WAVES and SWADE data sets, assuming that this is the dominant dissipation mechanism acting in the ocean surface layer and statistical measures of the corresponding fit indicate a substantial improvement over previous theoretical models. Comparisons are also carried out against more recent measurements, showing good order‐of‐magnitude agreement, even when shallow‐water effects are important.
Origin and pathway of the Luzon Undercurrent identified by a simulated adjoint tracer
Authors: Gao Shan , Qu Tangdong , Hu Dunxin
Published: April 2012

The origin and pathway of Luzon Undercurrent (LUC) water are investigated using a simulated adjoint tracer, based on circulation estimates of a global general circulation model. The results demonstrate that most of the LUC water comes from the subtropical North Pacific, confirming the earlier hypothesis on its relation to the northward shift of the North Equatorial Current (NEC) bifurcation at subsurface. Of the total volume of initially tracer‐tagged LUC water, approximately 41% is traced back to the winter mixed layer in the Kuroshio extension after 50 years of integration, coinciding with the formation of subtropical mode waters, while the rest is trapped in the northern subtropical gyre with its density >26.8 kg m−3, indicative of a significant South Pacific origin. As these waters move toward the western boundary, they get mixed and finally reach the density range of the LUC water. This result provides quantitative evidence for the dramatic impact of mixing on the route of subtropical water to becoming the LUC water.
Atmospheric Infrared Sounder (AIRS) sounding evaluation and analysis of the pre‐convective environment
Authors: Botes Danelle , Mecikalski John R. , Jedlovec Gary J.
Published: April 2012

The Atmospheric Infrared Sounder (AIRS) is a hyperspectral instrument onboard the National Aeronautics and Space Administration's (NASA) Earth Observing System (EOS) Aqua satellite. This study investigates the performance of AIRS soundings in characterizing the stability in the pre‐convective environment of the southeastern United States. AIRS soundings are collocated with radiosonde observations within ±1 degree and 2 h of the Aqua overpass. For each case, the AIRS sounding with maximum PBest quality indicator (signifying the pressure level above which the sounding is of best quality) is chosen for analysis. Rapid Update Cycle soundings from 1800 UTC analyses are used to evaluate the results from AIRS. Precipitable water and stability indices including convective available potential energy, convective inhibition, Lifted Index, K‐Index, and Total Totals are derived from all soundings. Results indicate that AIRS underestimates instability due to a dry bias at the surface and roughly 900 hPa. A simple method is presented for reconstructing a RAOB‐like inversion (in terms of magnitude and altitude) within AIRS soundings, hence developing more representative RAOB‐like soundings that can benefit the operational forecaster.
Impact of a cloud thermodynamic phase parameterization based on CALIPSO observations on climate simulation
Authors: Cheng Anning , Xu Kuan‐Man , Hu Yongxiang , Kato Seiji
Published: April 2012

This study examines the impact of a new cloud thermodynamic phase parameterization on climate simulation. The new parameterization is based on CALIPSO (Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation) observations and replaces the default parameterization in the Community Atmosphere Model version 4. It is shown that the application of the new cloud phase parameterization results in a small increase in global‐mean liquid water path (LWP) and a small decrease in global‐mean ice water path (IWP). Large regional increases in LWP mainly occur in tropical regions such as the western Pacific warm pool and northeastern Indian Ocean and middle latitudes, while large decreases in IWP occur in the midlatitude storm track regions. The increase in zonal‐mean cloud water content occurs at temperatures between −15°C and −30°C and cloud fraction increases occur at higher altitudes near the −30°C isotherm. Two other sensitivity experiments that favor more ice‐phase clouds also increase cloud fractions at the same altitudes, but decrease cloud water content at slightly lower altitudes. It is found that relative humidity increases at the same altitudes where the cloud fraction increases, caused by radiative cooling that is induced by cloud fraction increases but not changes in cloud water content. This result points to a deficiency in cloud fraction parameterizations that rely solely on ambient humidity without taking cloud water/ice content into account. Zonal‐mean cloud albedo forcing is sensitive to LWP in mixed‐phase clouds and the comparison with observations suggests that the CALIPSO and default parameterizations perform well in the extratropical regions.
Assimilating remote sensing observations of leaf area index and soil moisture for wheat yield estimates: An observing system simulation experiment
Authors: Nearing G. S. , Crow W. T. , Thorp K. R. , Moran M. S. , Reichle R. H. , Gupta H. V.
Published: April 2012

Observing system simulation experiments were used to investigate ensemble Bayesian state‐updating data assimilation of observations of leaf area index (LAI) and soil moisture (θ) for the purpose of improving single‐season wheat yield estimates with the Decision Support System for Agrotechnology Transfer (DSSAT) CropSim‐Ceres model. Assimilation was conducted in an energy‐limited environment and a water‐limited environment. Modeling uncertainty was prescribed to weather inputs, soil parameters and initial conditions, and cultivar parameters and through perturbations to model state transition equations. The ensemble Kalman filter and the sequential importance resampling filter were tested for the ability to attenuate effects of these types of uncertainty on yield estimates. LAI andθobservations were synthesized according to characteristics of existing remote sensing data, and effects of observation error were tested. Results indicate that the potential for assimilation to improve end‐of‐season yield estimates is low. Limitations are due to a lack of root zone soil moisture information, error in LAI observations, and a lack of correlation between leaf and grain growth.
Stability of weather regimes during the last millennium from climate simulations
Authors: Yiou Pascal , Servonnat Jérôme , Yoshimori Masakazu , Swingedouw Didier , Khodri Myriam , Abe‐Ouchi Ayako
Published: April 2012

The variability of the extra‐tropical atmospheric circulation and its potential dependence on external forcings have been debated topics in climate modeling and observation communities. A recent reconstruction of the North Atlantic Oscillation Index has argued that the Medieval Warm Period period yielded a persistent positive phase of this index in contrast with an oscillating mode during the Little Ice Age. This paper tests whether this feature can be obtained, in millennium simulations from three different climate models. We examine the daily atmospheric dynamics that drives the main modes of extra‐tropical variability. We find that the transition from a Medieval Warm Period to a Little Ice Age in the North Atlantic does not imply changes in patterns or frequency of weather regimes, although the mean surface temperature change is significant. This implies that the interpretation of proxy records in terms of atmospheric variability should be revised in order to take into account the structure of daily meteorological patterns, and/or climate models are too constrained to infer large changes of atmospheric variability.
Fertilization effects on the ecohydrology of a southern California annual grassland
Authors: Parolari A. J. , Goulden M. L. , Bras R. L.
Published: April 2012

Nitrogen limits leaf gas exchange, canopy development, and evapotranspiration in many ecosystems. In dryland ecosystems, it is unclear whether increased anthropogenic nitrogen inputs alter the widely recognized dominance of water and energy constraints on ecohydrology. We use observations from a factorial irrigation and fertilization experiment in a nitrogen‐limited southern California annual grassland to explore this hypothesis. Our analysis shows growing season soil moisture and canopy‐scale water vapor conductance are equivalent in control and fertilized plots. This consistency arises as fertilization‐induced increases in leaf area index (LAI) are offset by reduced leaf area‐based stomatal conductance,gs. We interpret this as evidence of a hydraulic feedback between LAI, plant water status, and gs, not commonly implemented in evapotranspiration models. These results support the notion that canopy physiology and structure are coordinated in water‐limited ecosystems to maintain a transpiration flux tightly controlled by hydraulic constraints in the soil‐vegetation‐atmosphere pathway.
Significant statistics
Authors: Pulverer Bernd
Published: April 2012

Appropriate statistical analysis is vital to the integrity of the scientific record, but experience and intuition also play a role in interpreting results. Scientific progress should not be hampered through statistical over‐evaluation.
The phage-host interaction as a model for studying carbon regulation in aquatic system
Authors: Sanmukh Swapnil , Paunikar Waman , Meshram Dilip , Lokhande Satish , Ghosh Tarun
Published: April 2012

This document contains the presentation by Swapnil G Sanmukh et al, National Environmental Engineering Research Institute (NEERI), Nagpur on “The phage-host interaction as a model for studying carbon regulation in aquatic system” during Second National Research Conference on Climate Change, organized by the Centre for Science and Environment, IIT Delhi and IIT Madras on November 5-6, 2011 at New Delhi.
Endoscopy
Authors: P Perumal
Published: April 2012

Endoscopy is a minimally invasive diagnostic medical procedure that is used to assess the interior surfaces of an organ by inserting a tube into the body. The instrument may have a rigid or flexible tube and not only provide an image for visual inspection and photography, but also enable taking biopsies and retrieval of foreign objects. Endoscopy is the vehicle for minimally invasive surgery and patients may receive conscious sedation so they do not have to be consciously aware of the discomfort. Many endoscopic procedures are considered to be relatively painless and, at worst, associated with moderate discomfort.
Analysis of acceptance of bacillus to various heavy metals and antibiotics
Authors: Sisodia Yamini Singh , Bajpai Vivek , Gaur Deeksha , Jain Pankaj Kumar
Published: April 2012

The present study was carried out to systematically examine the pathogenic microorganisms in sewage samples isolated from the Shekhawati region of Rajasthan. In this survey, 26 bacterial strains were isolated and identified using biochemical and molecular methods. Molecular identification of isolates was done by DNA isolation, PCR amplification using 16S rDNA primer and partial sequencing of purified product after sequencing, out of 26, 10 sequences were submitted to NCBI. Out of these 10 isolates Bacillus pumilis, Bacillus subtilis and Bacillus licheniformis were taken for further studies. There is growing awareness of the need for development of new antimicrobial agents for the treatment of human, animal and plant diseases. Keeping this fact in mind, we did the antibiotic susceptibility of these isolates against various antibiotics (Ampicillin, Erythromycin, Chloramphenicol etc.) by measuring zone of inhibition in Mueller Hinton agar plate by Kirby Bauer method comparing with growth pattern at different pH, temperature and various other environmental factors. Results of present studies indicates that the strains isolated from sewage water are resistant to most of the antibiotics and susceptible to Chromium , Cadmium, Mercury and some other heavy meals whereas Zinc and Iron are supporting the growth of bacillus at various parameters. Till date B.licheniformis has been checked for its resistance pattern to eight heavy metals. This study can be used for bioremediation of the environmental hazards and recombinants will also be examined for the same against positive strains.
Intrarectal administration of hCG (Human Choriogonadotropin) and fat loss as assessed by Dual energy X-ray absorptiometry (DXA) in experimental animals.
Authors: Belluscio Daniel , Klimovsky Ezequiel , Kaniuk Alejandro , Vaney Sergio
Published: April 2012

Our studies suggest that in experimental animals, submitted to a hypocaloric diet, the intrarectal administration of hCG (Human Chorionic Gonadotropin) decreases body fat and increases lean mass content in relative values to a greater extent that control animals who did not receive hCG.
Changing the Culture of “Ding”: Education, Legislation and Research on Concussive Brain Injury in Youth Athletics
Authors: Overturf Claire , Cooper Donald
Published: April 2012

The number of emergency department visits concerning sport related TBI in youth increased 57% from 2001 to 2009 and while a fraction of that increase may be attributed to injuries that were once missed now being identified due to greater general awareness, the fact remains that there are nearly 200,000 children every year who suffer sport related concussion or other TBI serious enough to prompt a visit to the ED. 40% of sports related concussions involve children between the ages of 8 and 13, and in this group the rate of concussion doubled between 1997 and 2007. The risk of concussion is highest in football and there are nearly 67,000 diagnosed concussions in high school football every year. In other sports that males and females play, such as basketball, girls seem to be at a higher risk. In high schools, concussions account for 15% of all sports related injuries resulting in at least one day of play lost. The risk of a suffering a concussion when participating in a contact sport may be as high as 20% per season. In both girls’ and boys’ soccer and basketball 20% of the concussions were repeat concussions. These statistics just further illustrate the gravity of the problem of sport related concussions. Here we describe the need for more work on education, legislation and research in order to change in the concussion/mTBI culture.
The AMPK-related kinase SIK2 is regulated by cAMP via phosphorylation at Ser358 in adipocytes
Authors: Henriksson Emma , Jones Helena A. , Patel Kashyap , Peggie Mark , Morrice Nicholas , Sakamoto Kei , Göransson Olga
Published: April 2012

SIK2 (salt-inducible kinase 2) is a member of the AMPK (AMP-activated protein kinase) family of kinases and is highly expressed in adipocytes. We investigated the regulation of SIK2 in adipocytes in response to cellular stimuli with relevance for adipocyte function and/or AMPK signalling. None of the treatments, including insulin, cAMP inducers or AICAR (5-amino-4-imidazolecarboxamide riboside), affected SIK2 activity towards peptide or protein substrates in vitro. However, stimulation with the cAMP-elevating agent forskolin and the β-adrenergic receptor agonist CL 316,243 resulted in a PKA (protein kinase A)-dependent phosphorylation and 14-3-3 binding of SIK2. Phosphopeptide mapping of SIK2 revealed several sites phosphorylated in response to cAMP induction, including Ser358. Site-directed mutagenesis demonstrated that phosphorylation of Ser358, but not the previously reported PKA site Ser587, was required for 14-3-3 binding. Immunocytochemistry illustrated that the localization of exogenously expressed SIK2 in HEK (human embryonic kidney)-293 cells was exclusively cytosolic and remained unchanged after cAMP elevation. Fractionation of adipocytes, however, revealed a significant increase of wild-type, but not Ser358Ala, HA (haemagglutinin)–SIK2 in the cytosol and a concomitant decrease in a particulate fraction after CL 316,243 treatment. This supports a phosphorylation-dependent relocalization in adipocytes. We hypothesize that regulation of SIK2 by cAMP could play a role for the critical effects of this second messenger on lipid metabolism in adipocytes.
Open-Door Cervical Laminoplasty with Preservation of Posterior Structures
Authors: Abdullah Kalil G. , Yamashita Takayuki , Steinmetz Michael P. , Lubelski Daniel , Wang Jeffrey C. , Benzel Edward C. , Mroz Thomas E.
Published: April 2012

Objective

To demonstrate that preservation of all posterior structures during open-door laminoplasty (ODL) is associated with a significant preservation of motion.

Methods

Fifteen patients underwent cervical ODL by one surgeon for treatment of cervical spondylotic myelopathy. An open-door technique was employed, and the laminae on the open side were reconstructed using miniplates with allograft strut bone graft. All spinous processes and interspinous and supraspinous ligaments were preserved within the operative levels and between supra- and subjacent levels in all patients. Postoperative radiographs were obtained 1.5, 3, 6, and 12 months. Computed tomography scans were obtained at 12 months.

Results

There were no significant intraoperative or perioperative complications. Postoperatively, the neutral angle was 6.8 ± 11.5 degrees (95% confidence interval: 0.5 to 13.1), representing a loss of lordosis of 3 degrees (not significant). The difference between the preoperative and postoperative arc range of motion was 5.96 ± 11.9 degrees (confidence interval: −0.62 to 12.5). The average percent loss of motion was 3.5% ± (0.1 to 6.9%). Four patients had an increased range of motion postoperatively.

Conclusion

Open-door laminoplasty with preservation of all posterior structures provides greater preservation of motion than has been previously described.
Uncovertebral Anatomic Midline Targeting for Cervical Disc Arthroplasty
Authors: Bednar Drew A.
Published: April 2012

Study Design

Prospective observational cohort.

Objective

To document the accuracy of uncovertebral anatomic targeting in positioning cervical disc arthroplasty.

Summary of Background Data

Disc arthroplasty implants depend on midline placement for optimum mechanical function. Fluoroscopy is used to delineate the midline. Anatomic targeting from the uncovertebral joints in the neck may be adequate. We have investigated the efficacy of uncovertebral anatomic targeting for cervical disc arthroplasty.

Methods

Anatomic uncovertebral midline targeting for disc arthroplasty insertion was performed in 18 male (mean age 51 years, range 27 to 67) and 22 female (mean age 50, range 35 to 70) patients receiving a total of 59 implants over a 5-year period. Device insertion was under only lateral imaging control. Postinsertion operative fluoroscopy with optimized centering was used to record implant position in the anteroposterior plane, and centerline analysis was performed using cursor measurement technology from the GE PACS™ imaging system (GE Medical Systems, Mt. Prospect, IL).

Results

Analysis found a mean deviation from the ideal midline placement of only 0.7 mm (range, 0 to 2.9 mm). Only three devices were more than 2 mm off the anatomic midline.

Conclusion

This anatomic technique is effective, safely minimizing imaging resource needs and X-ray exposure to the patient and operating team.
Observations of electron phase-space holes driven during magnetic reconnection in a laboratory plasma
Authors: Fox W. , Porkolab M. , Egedal J. , Katz N. , Le A.
Published: April 2012

This work presents detailed experimental observations of electron phase-space holes driven during magnetic reconnection events on the Versatile Toroidal Facility. The holes are observed to travel on the order of or faster than the electron thermal speed, and are of large size scale, with diameter of order 60 Debye lengths. In addition, they have 3D spheroidal structure with approximately unity aspect ratio. We estimate the direct anomalous resistivity due to ion interaction with the holes and find it to be too small to affect the reconnection rate; however, the holes may play a role in reining in a tail of accelerated electrons and they indicate the presence of other processes in the reconnection layer, such as electron energization and electron beam formation.
Production of internal transport barriers via self-generated mean flows in Alcator C-Mod
Authors: Fiore C. L. , Ernst D. R. , Podpaly Y. A. , Mikkelsen D. , Howard N. T. , Lee Jungpyo , Reinke M. L. , Rice J. E. , Hughes J. W. , Ma Y. , Rowan W. L. , Bespamyatnov I.
Published: April 2012

New results suggest that changes observed in the intrinsic toroidal rotation influence the internal transport barrier (ITB) formation in the Alcator C-Mod tokamak [E. S. Marmar and Alcator C-Mod group, Fusion Sci. Technol. 51, 261 (2007)]. These arise when the resonance for ion cyclotron range of frequencies (ICRF) minority heating is positioned off-axis at or outside of the plasma half-radius. These ITBs form in a reactor relevant regime, without particle or momentum injection, with Ti ≈ Te, and with monotonic q profiles (qmin < 1). C-Mod H-mode plasmas exhibit strong intrinsic co-current rotation that increases with increasing stored energy without external drive. When the resonance position is moved off-axis, the rotation decreases in the center of the plasma resulting in a radial toroidal rotation profile with a central well which deepens and moves farther off-axis when the ICRF resonance location reaches the plasma half-radius. This profile results in strong E × B shear (>1.5 × 105 rad/s) in the region where the ITB foot is observed. Gyrokinetic analyses indicate that this spontaneous shearing rate is comparable to the linear ion temperature gradient (ITG) growth rate at the ITB location and is sufficient to reduce the turbulent particle and energy transport. New and detailed measurement of the ion temperature demonstrates that the radial profile flattens as the ICRF resonance position moves off axis, decreasing the drive for the ITG the instability as well. These results are the first evidence that intrinsic rotation can affect confinement in ITB plasmas.
Selective deuteron production using target normal sheath acceleration
Authors: Morrison J. T. , Storm M. , Chowdhury E. , Akli K. U. , Feldman S. , Willis C. , Daskalova R. L. , Growden T. , Berger P. , Ditmire T. , Van Woerkom L. , Freeman R. R.
Published: April 2012

We report on the first successful demonstration of selective deuteron acceleration by the target normal sheath acceleration mechanism in which the normally overwhelming proton and carbon ion contaminant signals are suppressed by orders of magnitude relative to the deuteron signal. The deuterium ions originated from a layer of heavy ice that was deposited on to the rear surface of a 500 nm thick membrane of Si3N4 and Al. Our data show that the measured spectrum of ions produced by heavy ice targets is comprised of ∼99% deuterium ions. With a laser pulse of approximately 0.5 J, 120 fs duration, and ∼5×1018Wcm-2 mean intensity, the maximum recorded deuterium ion energy and yield normal to the target rear surface were 3.5 MeV and 1.2×1012sr−1, respectively.
Deuterium gas puff Z-pinch at currents of 2 to 3 mega-ampere
Authors: Klir D. , Shishlov A. V. , Kubes P. , Rezac K. , Fursov F. I. , Kokshenev V. A. , Kovalchuk B. M. , Kravarik J. , Kurmaev N. E. , Labetsky A. Yu. , Ratakhin N. A.
Published: April 2012

Deuterium gas-puff experiments have been carried out on the GIT-12 generator at the Institute of High Current Electronics in Tomsk. The emphasis was put on the study of plasma dynamics and neutron production in double shell gas puffs. A linear mass density of deuterium (D2) varied between 50 and 85 μg/cm. Somewhat problematic was a spread of the D2 gas at a large diameter in the central anode–cathode region. The generator operated in two regimes, with and without a plasma opening switch (POS). When the POS was used, a current reached a peak of 2.7 MA with a 200 ns rise time. Without the POS, a current rise time approached 1500 ns. The influence of different current rise times on neutron production was researched. Obtained results were important for comparison of fast deuterium Z-pinches with plasma foci. Average DD neutron yields with and without the POS were about 1011. The neutron yield seems to be dependent on a peak voltage at the Z-pinch load. In all shots, the neutron emission started during stagnation. At the beginning of the neutron production, the neutron emission correlated with soft x-rays and a significant fraction of neutrons could be explained by the thermonuclear mechanism. Nevertheless, a peak of the neutron emission occurred 40 ns after a soft x-ray peak. At this very moment, hard x-rays above 1 MeV were detected and a rapid expansion with a velocity of 3×105 m/s was observed. In the case of the POS, 1 MeV widths of radial neutron spectra implied that there are deuterons with the energy above 200 keV moving in the radial direction. On the basis of D2 gas puff experiments in the 0.3–17 MA region, the neutron yield dependence on a current as Y∝I3.0±0.2 was proposed.
Observations of Kelvin-Helmholtz instability at the air-water interface in a circular domain
Authors: Bye John A. T. , Ghantous Malek
Published: April 2012

We present an analysis of Kelvin-Helmholtz instability in a circular domain in the limit of the azimuthal integer wavenumber, n → ∞ which reproduces the classical results for a rectilinear geometry at the rim, provided that the additional condition that the surface current to surface wind ratio is (ρ1/ρ2)1/2 where ρ1 and ρ2 are respectively the densities of air and water, is satisfied. Experiments were carried out in a circular rig of radius 0.19 m in which a family of unstable waveforms with n ≈ 60 were observed with properties (including the additional condition) in approximate agreement with theory. The additional condition is consistent with the absence of a surface shear stress in the instability process.
Amplification of the linear and nonlinear optical response of a chiral molecular crystal
Authors: Domingos Sérgio R. , Silva Pedro S. Pereira , Buma Wybren Jan , Garcia M. Helena , Lopes Nelson C. , Paixão José António , Silva Manuela Ramos , Woutersen Sander
Published: April 2012

We have observed large second-order nonlinear optical and vibrational circular dichroism (VCD) responses in a charge-transfer-type L-Histidinium salt. Using X-ray Diffraction, VCD spectroscopy, and time-dependent density functional theory to characterize the compound, we employ a two-level model to explain and quantify the strongly enhanced optical signals. We find that both linear and nonlinear optical responses are greatly enhanced by a single low-lying charge-transfer state.
The J = 1 para levels of the v = 0 to 6 np singlet Rydberg series of molecular hydrogen revisited
Authors: Glass-Maujean M. , Schmoranzer H. , Haar I. , Knie A. , Reiss P. , Ehresmann A.
Published: April 2012

The energies and the widths of the J = 1 para levels of the v = 0 to 6 Rydberg np singlet series of molecular hydrogen with absolute intensities of the R(0) and P(2) absorption lines were measured by a high – resolution synchrotron radiation experiment and calculated through a full ab initio multichannel quantum defect theory approach. On the basis of the agreement between theory and experiment, 31 levels were either reassigned or assigned for the first time.
A resonance mechanism of efficient energy transfer mediated by Fenna-Matthews-Olson complex
Authors: Alicki Robert , Miklaszewski Wiesław
Published: April 2012

The Wigner-Weisskopf-type model developed by Alicki and Giraldi [J. Phys. B 44, 154020 (2011)]10.1088/0953-4075/44/15/154020 is applied to the biological process of energy transfer from a large peripheral light harvesting antenna to the reaction center. This process is mediated by the Fenna-Matthews-Olson (FMO) photosynthetic complex with a remarkably high efficiency. The proposed model provides a simple resonance mechanism of this phenomenon employing exciton coherent motion and is described by analytical formulas. A coupling to the vibrational environment is a necessary component of this mechanism as well as a fine-tuning of the FMO complex Hamiltonian. The role of the relatively strong coupling to the energy sink in achieving the resonance condition and the absence of heating of the vibrational environment are emphasized.
Three dimensional density cavities in guide field collisionless magnetic reconnection
Authors: Markidis S. , Lapenta G. , Divin A. , Goldman M. , Newman D. , Andersson L.
Published: April 2012

Particle-in-cell simulations of collisionless magnetic reconnection with a guide field reveal for the first time the three dimensional features of the low density regions along the magnetic reconnection separatrices, the so-called cavities. It is found that structures with further lower density develop within the cavities. Because their appearance is similar to the rib shape, these formations are here called low density ribs. Their location remains approximately fixed in time and their density progressively decreases, as electron currents along the cavities evacuate them. They develop along the magnetic field lines and are supported by a strong perpendicular electric field that oscillates in space. In addition, bipolar parallel electric field structures form as isolated spheres between the cavities and the outflow plasma, along the direction of the low density ribs and of magnetic field lines.
A comparison of the value of viscosity for several water models using Poiseuille flow in a nano-channel
Authors: Markesteijn A. P. , Hartkamp Remco , Luding S. , Westerweel J.
Published: April 2012

The viscosity-temperature relation is determined for the water models SPC/E, TIP4P, TIP4P/Ew, and TIP4P/2005 by considering Poiseuille flow inside a nano-channel using molecular dynamics. The viscosity is determined by fitting the resulting velocity profile (away from the walls) to the continuum solution for a Newtonian fluid and then compared to experimental values. The results show that the TIP4P/2005 model gives the best prediction of the viscosity for the complete range of temperatures for liquid water, and thus it is the preferred water model of these considered here for simulations where the magnitude of viscosity is crucial. On the other hand, with the TIP4P model, the viscosity is severely underpredicted, and overall the model performed worst, whereas the SPC/E and TIP4P/Ew models perform moderately.
Production of high-density high-temperature plasma by collapsing small solid-density plasma shell with two ultra-intense laser pulses
Authors: Xu H. , Yu Wei , Yu M. Y. , Wong A. Y. , Sheng Z. M. , Murakami M. , Zhang J.
Published: April 2012

Three-dimensional particle-in-cell simulations show that the anisotropic collapse of a plasma microshell by impact of two oppositely directed intense laser pulses can create at the center of the shell cavity a submicron-sized plasma of high density and temperature suitable for generating fusion neutrons.
A highly stable DC power supply for precision magnetic field measurements and other purposes
Authors: Ino Takashi
Published: April 2012

A homogeneous magnetic field is essential for the 3He neutron spin filter used to polarize neutron beams and analyze neutron spins in neutron scattering. The required spatial uniformity of the magnetic field is on the order of 10−4/cm or less. To measure such uniformity, one needs a DC current source with a current stability much better than 10−4. However, laboratory DC power supplies, which are commonly used in many 3He neutron spin filters, do not have such stabilities. To attain a highly stable current with a common laboratory DC power supply for every 3He neutron spin filter, a simple feedback circuit has been developed to keep the output current stable up to 10−6. Such a highly stable current or voltage from a common laboratory DC power supply can also be used for various other research applications.
Experimental study of the ion current to a cylindrical Langmuir probe taking into account a finite ion temperature
Authors: Díaz-Cabrera J. M. , Lucena-Polonio M. V. , Fernández Palop J. I. , Morales Crespo R. , Hernández M. A. , Tejero-del-Caz A. , Ballesteros J.
Published: April 2012

This article deals with the experimental verification of a theoretical radial model, developed by the authors, for the sheath that surrounds a cylindrical Langmuir probe immersed in a plasma in which the positive ion temperature, Ti, is not negligibly small compared to the electron temperature, Te. The theoretical model is a generalization of the classical one developed for cold ions by Allen, Boyd, and Reynolds for the case of spherical probes, and extended by Chen for cylindrical ones. According to our theory, due to the positive ion thermal motion the ion current collected by the probe is increased with respect to the case of cold ions, so its influence must be considered in plasma diagnosis. An experimental device to accurately measure the I-V characteristic of a cylindrical probe in plasma, for which Ti/Te ≠ 0, has been developed. Very good agreement has been found between the theoretical positive ion I-V probe characteristic and the experimental values by using a Sonin plot.
Low frequency noise in La0.7Sr0.3MnO3 based magnetic tunnel junctions
Authors: Guerrero R. , Solignac A. , Fermon C. , Pannetier-Lecoeur M. , Lecoeur Ph. , Fernández-Pacheco R.
Published: April 2012

Magnetic tunnel junctions based on manganites can exhibit a high tunneling magnetoresistance ratio due to the almost full spin polarization at the Fermi level. However, the performances of magnetic tunnel junction devices are also strongly linked to their noise characteristics. Here, we present a low frequency noise study on fully epitaxial La0.7Sr0.3MnO3/SrTiO3/La0.7Sr0.3MnO3/La0.66Sr0.33Mn0.995Ru0.005O3 tunnel spin valves with tunneling magnetoresistance ratios larger than 100%. We evidence non-conventional low frequency noise dependence on temperature related to the magnetic fluctuations and structural phase transitions in the structure. We present also a comparison with the low frequency noise exhibited in Fe/MgO/Fe magnetic tunnel junctions.
Operation of multi-finger graphene quantum capacitance varactors using planarized local bottom gate electrodes
Authors: Ebrish M. A. , Shao H. , Koester S. J.
Published: April 2012

The operation of multi-finger graphene quantum capacitance varactors fabricated using a planarized local bottom gate electrode, HfO2 gate dielectric, and large-area graphene is described. As a function of the gate bias, the devices show a room-temperature capacitance tuning range of 1.22–1 over a voltage range of ±2 V. An excellent theoretical fit of the temperature-dependent capacitance-voltage characteristics is obtained when random potential fluctuations with standard deviation of 65 mV are included. The results represent a first step in realizing graphene quantum capacitance varactors for wireless sensing applications.
Resistivity in the dynamic current sheath of a field reversed configuration
Authors: Kayama M. E.
Published: April 2012

The resistivity of a field reversed configuration in a theta-pinch with slow rising current was investigated during the turbulent phase from the moment of field reversal until end of plasma radial implosion. This transport coefficient was obtained in a hydrogen plasma by local measurements with magnetic probe and compared to numerical calculations with Chodura resistivity and evolution of lower hybrid drift instability. The values of resistivity are higher than those predicted by classical binary collision. During early phase of confinement, the doubly layer structure of current sheath in the low electric field machine was theoretically well reproduced with anomalous collision frequency calculated with Chodura resistivity that provides appropriate conditions for onset of lower hybrid drift instability and the regular evolution of pinch. The plasma dynamic, radial profiles of magnetic field during the radial compression and resistivity values were equally close to those observed by the measurements.
Fluorescence properties and energy transfer study of Er3+/Nd3+ doped fluorophosphate glass pumped at 800 and 980 nm for mid-infrared laser applications
Authors: Tian Ying , Xu Rongrong , Hu Lili , Zhang Junjie
Published: April 2012

The fluorescence properties of 2.7 μm emission as well as near infrared emissions in Er3+/Nd3+ doped fluorophosphate glasses are investigated under 800 and 980 nm excitation. The fluorescence dynamics and energy transfer processes between Er and Nd ions in different pumping schemes are reported. Three Judd-Ofelt intensity parameters, energy transfer microparameters, and efficiency have been determined using the Judd-Ofelt and Förster-Dexter theories. The calculated energy transfer efficiency of the Er3+:4I13/2 level to the Nd3+:4I15/2 level is as high as 83.91%. The results indicate that Nd3+ may be an efficient sensitizer for Er3+ to obtain mid-infrared emission and the more suitable pumping scheme of 2.7 μm laser applications for Er3+/Nd3+ doped fluorophosphate glass is 980 nm excitation.
Fluorinated copper-phthalocyanine/cobalt-phthalocyaine organic heterojunctions: Charge transport and Kelvin probe studies
Authors: Debnath A. K. , Kumar Arvind , Samanta S. , Prasad R. , Singh A. , Chauhan A. K. , Veerender P. , Singh S. , Basu S. , Aswal D. K. , Gupta S. K.
Published: April 2012

Organic heterojunctions comprising of n-type fluorinated copper-phthalocyanine (F16CuPc) and p-type cobalt-phthalocyanine (CoPc) layers were prepared on (001) LaAlO3 substrates. In the entire temperature range of 300–30 K, F16CuPc/CoPc heterojunctions showed an ohmic conduction with three order of magnitude lower resistivity than the individual layers. This indicates formation of a charge accumulation layer at the interface. Kelvin probe studies showed that charge accumulation layer is ∼10 nm thick on both the sides of the interface.
Fabrication, characterization, and optical modeling of a new architecture for organic photovoltaics: The vertically orientated stack device
Authors: Alley Nigel J. , Dias Sampath , Liao Kang-Shyang , Curran Seamus A.
Published: April 2012

We introduce a new architecture for organic photovoltaics based on vertically orientated devices. The fabrication, device characteristics, and an optical model of the stack organic photovoltaic (OPV) device are presented. This new architecture gives rise to an alternative to the common flat-panel structure, which was originally conceived for the first silicon devices. The OPV stack device has an increased short circuit current density, fill factor, and power-conversion efficiency, as opposed to the standard flat-panel device.