bluuebunny/crossref_metadata_2025 huggingface dataset:
Choose your menu wisely: cuisine-associated food-poisoning risks in restaurants in England and Wales
Authors: GORMLEY F. J. , RAWAL N. , LITTLE C. L.
Published: August 2011

The food service sector continues to be the most common setting for reported foodborne disease outbreaks in England and Wales. Using restaurant-associated foodborne outbreaks reported in England and Wales from 1992 to 2009, cuisine-specific risk factors were examined. Of 677 restaurant outbreaks, there were 11 795 people affected, 491 hospitalizations, and seven deaths; and Chinese, Indian, British and Italian cuisines were the most commonly implicated (26%, 16%, 13% and 10%, respectively).Salmonellaspp. accounted for most outbreaks of all cuisine types, and particularly Chinese (76%, 133/175) and Italian (55%, 38/69). Poultry meat was the most frequently implicated food vehicle in outbreaks associated with Indian (30%), Chinese (21%), and British (18%) cuisines while for Italian cuisine, desserts and cakes were more frequently implicated (33%). Rice dishes were also a common outbreak food vehicle in those restaurants serving Chinese (22%) and Indian (16%) cuisine. Cross-contamination was the biggest contributory factor associated with Chinese (46%), British (33%) and Indian (30%) cuisines whereas inadequate cooking (38%) and use of raw shell eggs in lightly cooked or uncooked food (35%) were more often associated with Italian cuisine. Over the surveillance period, the proportion ofSalmonellaEnteritidis PT4 outbreaks in restaurants serving Chinese cuisine significantly decreased (P<0·0001) and this was mirrored by an increase inS. Enteritidis non-PT4 outbreaks (P<0·0001). Despite this change in proportion, contributory factors such as cross-contamination have continued to cause outbreaks throughout the 18 years. The results show that by stratifying the risks associated with restaurants by cuisine type, specific evidence of food control failures can be used to target foodborne illness reduction strategies.
Subcostal real-time three-dimensional echocardiography of interatrial communications: reconstruction of an oval fossa defect, a superior sinus venosus defect with partially anomalous pulmonary venous drainage, an infero-posterior oval fossa defect, and a coronary sinus defect
Authors: Bilska Karolina M. G. , Kehrens Claudia M. J. , Riley Gillian , Anderson Robert H. , Marek Jan
Published: August 2011

Real-time three-dimensional echocardiography can surpass simple cross-sectional echocardiography in providing precise details of cardiac lesions. For the purpose of optimising treatment, we describe our findings with real-time three-dimensional echocardiography when interrogating different types of communications permitting interatrial shunting. A three-dimensional reconstruction of defects within the oval fossa enabled reliable identification of location, size, and integrity of surrounding rims. In the superior sinus venosus defect associated with partially anomalous pulmonary venous drainage, three-dimensional reconstruction helped to provide a better understanding of the relationship between the interatrial communication, the orifice of the superior caval vein, and the connections of the right upper pulmonary vein. In the defect opening infero-posteriorly within the oval fossa, three-dimensional reconstruction helped to avoid the risk of potentially inappropriate closure of the defect by suturing the hyperplastic Eustachian valve to the atrial wall, which could have diverted the inferior caval venous return into the left atrium, or obstructed the caval venous orifice. In the coronary sinus defect, three-dimensional echocardiography provided a ‘face to face’ view of the entire coronary sinus roof, showing a circular defect communicating with the cavity of the left atrium. Acquisition of the full-volume data sets took less than 2 minutes for the patients having defects within the oval fossa, and no more than 3 minutes for the patients with the sinus venosus and coronary sinus defects. Post-processing for the defects in the oval fossa took from 5 to 8 minutes, and from 12 to 16 minutes for the more complicated defects.

Conclusion

Cross-sectional two-dimensional echocardiography can establish correct diagnosis in all types of atrial communications; however, real-time three-dimensional reconstruction provides additional value to the surgeon and interventionist for better understanding of spatial intracardiac morphology.
Assessment of cardiac functions using tissue Doppler imaging in children with familial Mediterranean fever
Authors: Ozdemir Osman , Agras Pinar Isik , Aydin Yusuf , Abaci Ayhan , Hizli Samil , Akkus Halil Ibrahim , Fidan Cihan
Published: August 2011

Objective

Familial Mediterranean fever may carry a potential for cardiovascular disorders because of sustained inflammation during its course; however, there has been a limited number of studies investigating the cardiac functions in children. The aim of this study was to assess both ventricular diastolic functions using conventional echocardiography and tissue Doppler imaging in children with familial Mediterranean fever.

Patients and methods

The study population included 25 patients with familial Mediterranean fever – mean age was 11.8 plus or minus 5.30 years – and 23 healthy patients as controls – mean age was 9.88 plus or minus 3.69 years. Both ventricular functions were measured using echocardiography comprising standard M-mode and conventional Doppler and tissue Doppler imaging during an attack-free period.

Results

The conventional echocardiographic parameters with myocardial performance index were in normal ranges and similar in patients with familial Mediterranean fever and controls, with a p-value more than 0.05. However, right ventricular diastolic dysfunction was observed in patients with familial Mediterranean fever documented by tissue Doppler imaging, with a p-value less than 0.05 for E't and A't wave ratio.

Conclusion

Using tissue Doppler imaging, we have demonstrated that although left ventricular functions were comparable in the patients and healthy children, right ventricular diastolic function indices were impaired in patients with familial Mediterranean fever during childhood. Impaired right ventricular diastolic function may be an early manifestation of cardiac involvement in children with familial Mediterranean fever.
Socio-economic inequalities in overweight among adults in Turkey: a regional evaluation
Authors: Ergin Isil , Hassoy Hur , Kunst Anton
Published: August 2011

Objective

Patterns of socio-economic inequalities in obesity and overweight have not been documented for Turkey. The present study aimed to describe educational and wealth-related inequalities for overweight in Turkey, taking a regional perspective.

Design

Cross-sectional self-reported data of the World Health Survey 2002 for Turkey were used. BMI ≥ 25·00 kg/m2 was considered as overweight. Respondents were classified according to education years and a wealth score derived from the availability of household assets. Logistic regression analysis was applied to assess the relationship between overweight and socio-economic factors. Analyses were stratified by sex and region (West, Mediterranean, Middle, Black Sea and East).

Setting

Turkey.

Subjects

Among the respondents 20 years and older, 3790 women and 4057 men had data on self-reported height and weight.

Results

Age-adjusted overweight prevalence was 48·4 % for women and 46·1 % for men. For men, education was not systematically related to overweight while overweight was significantly increased among the highest wealth groups. For women, the prevalence of overweight was highest for low-educated and middle-wealth groups. The size of the inequalities in overweight showed only small regional variations. In the East, however, overweight prevalence was more related to higher socio-economic position than in the other regions.

Conclusions

Socio-economic inequalities for overweight in Turkey are at a similar level as in most European countries, and especially comparable to Southern Europe. The smaller inequalities in the East correspond to the low level of socio-economic development in this part of the country. Prevention of overweight should focus on lower educational groups throughout the entire country and especially on low-educated women.
SURFACE TEMPERATURE RECONSTRUCTION BASED ON THE THERMOCAPILLARY EFFECT
Authors: SELLIER M. , PANDA S.
Published: August 2011

A thin liquid film subject to a temperature gradient is known to deform under the action of thermocapillary stresses which induce convective cells. The free surface deformation can be thought of as the signature of the imposed temperature gradient, and this study investigates the inverse problem of trying to reconstruct the temperature field from known free surface variations. The present work builds on the analysis of Tan et al. [“Steady thermocapillary flows of thin liquid layers I. Theory”, Phys. Fluids A2 (1990) 313–321, doi:10.1063/1.857781] which provides a long-wave evolution equation for the fluid film thickness variation on nonuniformly heated substrates and proposes a solution strategy for the planar flow version of this inverse problem. The present analysis reveals a particular case for which there exists an explicit, closed-form solution expressing the local substrate temperature in terms of the local film thickness and its spatial derivatives. With some simplifications, this analysis also shows that this solution applies to three-dimensional flows. The temperature reconstruction strategies are successfully tested against “artificial” experimental data (obtained by solving the direct problem for known temperature profiles) and actual experimental data.
Set-up accuracy of an external immobilisation system for patients receiving radical radiotherapy for prostate cancer
Authors: d’Aquino Ashley , Harrison Shalini , Helyer Sarah , Dearnaley David , McNair Helen
Published: August 2011

Purpose: To evaluate the accuracy of an external immobilisation system in patients receiving radiotherapy for prostate cancer.

Methods: Portal Imaging data were audited in 20 patients treated using an in-house immobilisation system and 20 patients treated using an indexed commercial immobilisation system (Combifix™). Individual and group random and systematic errors were calculated to determine the accuracy of set-up using skin marks alone and with a no-action-level protocol.

Results: The initial results showed a larger systematic error in the Combifix™ in the anterior-posterior direction (2.7 mm) compared with the in-house system (1.5 mm). The possible source of this was identified as the difficulty in accurately aligning the laser to a curved couch top prior to setting the isocentre height. A change in the process of setting the isocentre was introduced, and comparable baseline set-up accuracy was achieved. This was with a systematic error of ≤2.0 mm and a random error ≤1.5 mm of patient position set-up error with skin marks alone, and using the Combifix™. The systematic errors were further reduced to <1 mm with an off-line no-action-level protocol.

Conclusion: Using the Combifix™ system a high level of set-up accuracy was reproduced in routine daily practice.
Introduction of domestic buffalo (Bubalus bubalis) into Ethiopia would be feasible
Authors: Desta Takele Taye
Published: August 2011

Due to its high agro-ecological variation and favorable production environment, Ethiopia has been endowed with high diversity of animal genetic resources and huge livestock population. However, the per capita consumption of livestock products is among the least in the world. To increase this consumption level, Ethiopia needs to keep livestock species that would be able to thrive under sub-optimal management systems, while providing some amount of products and services. The domestic buffalo (Bubalus bubalis) is one of the large ruminants that contribute to the least developed world's food and agriculture production. Therefore, introduction of the riverine-type buffalo would support food and agriculture production in Ethiopia. Moreover, the existing high demand for milk and meat, and the agro-ecological conditions are in favor of introduction of the riverine-type buffalo. More specifically, the riverine buffalo excels over indigenous cattle in its milk yield and quality of milk components. It also has a long productive life, a special ability of converting poor-quality roughage into animal protein, docile temperament and a wide range of adaptation. The presence of wild buffalo also shows Ethiopia's suitability for domestic buffalo rearing. Therefore, even though it seems illogical to make direct comparison between the performance of the Ethiopian indigenous cattle and the domestic buffaloes kept elsewhere; the hardy nature of buffalo and its wide range of adaptation would indicate the adaptation of the riverine-type buffalo in Ethiopia. However, the introduced riverine-type buffalo needs to be handled on experimental stations until management expertise is developed.
What promotes and inhibits cooperation in mental health care across disciplines, services and service sectors? A qualitative study
Authors: Bramesfeld A. , Ungewitter C. , Böttger D. , El Jurdi J. , Losert C. , Kilian R.
Published: August 2011

Aims.

To explore the practice of cooperation in mental health care across services and identify conditions that promote and inhibit cooperation.

Methods.

Focus groups with relevant service providers were conducted in four exemplary regions in Germany (rural/urban and East/West). The discussions were content analysed.

Results.

Seven central categories were deduced: (1) involved service providers, (2) comprehension, (3) reasons, (4) instruments for cooperation, (5) promoting and inhibiting conditions, (6) interdisciplinarity, and (7) regional and personal networks. Cooperation is practiced in networks, rather than defined relations. Who is involved in cooperation depends on patients/clients needs and may vary from case to case. Service providers do not have theoretical concepts of cooperation. Cooperation relies not only on personal contacts and knowledge between services but also on time, financial reimbursement and the social capital of the environment. In particular, cooperation with physicians was considered to be difficult by non-medical professionals. Physician's role models do not seem to include cooperation with other disciplines as a core task.

Conclusions.

To improve cooperation, regional and sustainable mental health networks have to be systematically implemented by providing leadership, time and reimbursement for network meetings. Interdisciplinary cooperation practice should be part of the curricula of medical students and residents in psychiatry.
The Calabrian Arc subduction complex in the Ionian Sea: Regional architecture, active deformation, and seismic hazard
Authors: Polonia A. , Torelli L. , Mussoni P. , Gasperini L. , Artoni A. , Klaeschen D.
Published: August 2011

We analyzed the structure and evolution of the external Calabrian Arc (CA) subduction complex through an integrated geophysical approach involving multichannel and single‐channel seismic data at different scales. Pre‐stack depth migrated crustal‐scale seismic profiles have been used to reconstruct the overall geometry of the subduction complex, i.e., depth of the basal detachment, geometry and structural style of different tectonic domains, and location and geometry of major faults. High‐resolution multichannel seismic (MCS) and sub‐bottom CHIRP profiles acquired in key areas during a recent cruise, as well as multibeam data, integrate deep data and constrain the fine structure of the accretionary wedge as well as the activity of individual fault strands. We identified four main morpho‐structural domains in the subduction complex: 1) the post‐Messinian accretionary wedge; 2) a slope terrace; 3) the pre‐Messinian accretionary wedge and 4) the inner plateau. Variation of structural style and seafloor morphology in these domains are related to different tectonic processes, such as frontal accretion, out‐of‐sequence thrusting, underplating and complex faulting. The CA subduction complex is segmented longitudinally into two different lobes characterized by different structural style, deformation rates and basal detachment depths. They are delimited by a NW/SE deformation zone that accommodates differential movements of the Calabrian and the Peloritan portions of CA and represent a recent phase of plate re‐organization in the central Mediterranean. Although shallow thrust‐type seismicity along the CA is lacking, we identified active deformation of the shallowest sedimentary units at the wedge front and in the inner portions of the subduction complex. This implies that subduction could be active but aseismic or with a locked fault plane. On the other hand, if underthrusting of the African plate has stopped recently, active shortening may be accommodated through more distributed deformation. Our findings have consequences on seismic hazard, since we identified tectonic structures likely to have caused large earthquakes in the past and to be the source regions for future events.
In the family with ubiquitin
Authors: Alexandru Gabriela , Pariente Nonia , Xirodimas Dimitris
Published: August 2011

The Cold Spring Harbor meeting on ‘The Ubiquitin family’, held in May 2011, brought together scientists from a wide range of fields, all under the common umbrella of ubiquitin and ubiquitin‐like protein structure, function and regulation.
Signalling in space and time: systems dynamics of intracellular communication
Authors: Tzlil Shelly , Kuruvilla Rejji
Published: August 2011

The EMBO Spatial meeting took place in May 2011 in Switzerland. It promoted interactions between cell biologists, neuroscientists, system biologists and mathematicians, all united by a common interest in understanding how cells integrate signals in space and time.
A feast for the senses: development and function of sensory systems
Authors: Streit Andrea , Raible David W
Published: August 2011

The EMBO Workshop, Frontiers in Sensory Development took place in May 2011 in Barcelona. The meeting brought together a diverse group of scientists to tackle the formation and function of the sensory nervous system in all its complexity.
Activity of Exoenzymes in Treated Wastewater Irrigated Soils
Authors: Jüschke Elisabeth , Marschner Bernd
Published: August 2011

The reuse of reclaimed wastewater for irrigation of agricultural fields greatly influences the activity of soil microorganisms through the input of organic compounds. Due to the production of exoenzymes by microorganisms for the decomposition of substrates it can be assumed that the irrigation with treated wastewater (TWW) has a strong influence on the soil enzyme pool. In this study the activity of ten exoenzymes, which catalyses processes in C, N and P nutrient cycles, were determined in 3 different soils in 0-10, 10-20, 20-30, 30-50, 50-70 and 70-100 cm soil depth. The soils were used for agriculture and irrigated with reclaimed wastewater reused after a secondary treatment step. Additionally a control after freshwater irrigation was studied. Due to the influence of TWW on the soil biology of these soils, also clear effects on soil exoenzymes in freshwater and TWW irrigated soils could be seen. According to Sinsabaugh et al. (2008) we calculated indices which describe the enzymatic resources for acquisition of organic P and organic N relative to C and therefore give insides into the functional convergence of extracellular enzyme activities in soils and the relative nutrient demand. The distribution pattern of these functional enzyme activities varied between freshwater and TWW irrigated soils and shows therefore a strong influence of the TWW irrigation on the activity of exoenzymes. (Sinsabaugh et al. (2008): Stoichiometry of soil enzyme activity at global scale. Ecology Letters 11 (11), 1252-1264.)
Attempts to explain and observe TCNQ behavior at 60 K
Authors: Lubkin Gloria B.
Published: August 2011

Considerable theoretical and experimental activity has been inspired by the report by a Penn group that they had observed superconducting fluctuations in an organic solid above 60 K. John Bardeen has published a possible explanation for the effect involving a coupling between electrons and a lattice wave. Bernd Matthias has criticized the quality of the experiment and attributes the observations to dirt and ferroelectricity. A group at Johns Hopkins University has done microwave conductivity experiments on one of the organic solids studied by the Penn group and does not find unusually high conductivity. And experimenters at Brown Boveri, who studied a different one-dimensional compound, believe that the Penn group might be observing spurious conductivities.
Element 104 identified by characteristic x rays
Authors: Cohn Ronald J.
Published: August 2011

A research team at the Oak Ridge National Laboratory has recently announced that they have conclusively identified the 257 isotope of element 104. This new work shows promise of shedding light on the controversy between Albert Ghiorso and Georgi N. Flerov, the leaders respectively of the groups at Lawrence Berkeley Laboratory and the Joint Institute for Nuclear Research, Dubna. The isotope 104X257 decays by alpha emission to 102No253 with a half-life of 4.3 seconds. The Oak Ridge group observed the K-series x rays from nobelium in coincidence with the alpha particles from 104X257; the observation of x-ray spectra has never been reported previously by the Berkeley or Dubna workers, according to Curtis E. Bemis Jr, spokesman for the group.
New giant resonances found near giant dipole resonance
Authors: Levi Barbara G.
Published: August 2011

For years a familiar feature of the nuclear spectrum has been the giant dipole resonance (GDR) located at (70–80)/A1/3 MeV with a width of several MeV. Recently nuclear physicists have been excited to find other giant resonances at neighboring or higher energies. The interesting feature of the discovery of this new multipole excitation is not so much its actual occurrence, for that was expected theoretically, but that its strength is concentrated in a sufficiently narrow energy range for it to form a giant resonance that can be detected experimentally. The most prominent of these new resonances appears to be an isoscalar quadrupole resonance located just a few MeV below the giant dipole and having a comparable width.
Fifty years of matter waves
Authors: Medicus Heinrich A.
Published: August 2011

Fifty years have passed since Louis de Broglie created the theory of matter waves and published his first papers on the subject—inaugurating the era of modern quantum mechanics. De Broglie's undertaking was a very bold one. Unlike Planck's work in the older quantum theory, which had its origin in the measurements of black-body radiation, and unlike the photon hypothesis of Einstein, where the early experiments on the photoelectric effect offered some corroboration, de Broglie's theory lacked the support of any direct experimental evidence. Had it not been for the intervention of such established figures as Langevin and Einstein, who recognized the importance of what he had accomplished, de Broglie's work probably would have had little immediate effect.
Diffusive behavior from a quantum master equation
Authors: Clark Jeremy , De Roeck W. , Maes Christian
Published: August 2011

We study a general class of translation invariant quantum Markov evolutions for a particle on \documentclass[12pt]{minimal}\begin{document}${\mathbb Z}^d$\end{document}Zd. The evolution consists of free flow, interrupted by scattering events. We assume spatial locality of the scattering events and exponentially fast relaxation of the momentum distribution. It is shown that the particle position diffuses in the long time limit. This generalizes standard results about central limit theorems for classical (non-quantum) Markov processes.
The interaction of hyperthermal nitrogen with N-covered Ag(111)
Authors: Ueta Hirokazu , Gleeson Michael A. , Kleyn Aart W.
Published: August 2011

A mixed beam of hyperthermal N atoms and N2 molecules was scattered from the N-covered Ag(111) surface held at 300 K. The angular distribution of scattered N atoms is very broad. In contrast, N2 molecules exhibit a sharp angular distribution. Taking into account the relative mass ratio, N loses more energy at the surface than N2. In terms of energy loss, the atoms approximately follow the binary collision model while the molecules do not. Instead, the energy curves of scattered N2 are more comparable to the parallel momentum conservation model for near specular outgoing angles (40°–65°). For both atoms and molecules the angle-resolved intensity and final energy curves are very similar to those from the bare surface. However, the N-covered surface yields non-negligible N2 intensity for a broad range of outgoing angles, including along the surface normal. This was not the case from the clean surface, where the measured intensity distribution was confined to the narrower angular range indicated above. Backscattering and direct abstraction reactions are evaluated as possible origins of this additional N2 signal. Of these, an abstraction mechanism appears to be the most consistent with the measured data.
Investigation of the anisotropic strain relaxation in GaSb islands on GaP
Authors: Wang Y. , Ruterana P. , Lei H. P. , Chen J. , Kret S. , El Kazzi S. , Desplanque L. , Wallart X.
Published: August 2011

The strain relaxation at the initial stages of highly mismatched (11.8%) GaSb grown on a GaP substrate following a Ga-rich surface treatment by molecular beam epitaxy has been investigated. High resolution transmission electron microscopy and moiré fringe analysis were used to determine the relaxation state in these GaSb islands in the [110] and [1–10] directions. The measurements revealed an anisotropic strain relaxation in these two directions; there is a higher misfit strain relaxation along the [110] direction where the islands are elongated, which is in agreement with a higher density of misfit dislocations. By combining molecular dynamics simulations and TEM results, the anisotropy in the strain relaxation is shown to be related to the asymmetry in the formation of interface misfit dislocations. The P-core glide set 60° dislocations (α type) and the Ga-core shuffle set Lomer dislocations serve as the primary misfit dislocation which contributes to the strain relaxation in the (1–10) interface, and the Ga-core glide set 60° dislocations (β type) and the P-core shuffle set Lomer dislocations for the (110) interface, respectively. The lower formation energy and higher glide velocity of the P-core glide set 60° dislocations (α type) result in a higher line density and more uniform periodical distribution of the misfit dislocation in the (1–10) interface. The higher fraction of Lomer dislocations, which is related to the dislocation configuration stability and surface treatment, promotes a better strain relief in the (1–10) interface, with a corresponding elongation of islands in the [110] direction.
Application of amorphous carbon based materials as antireflective coatings on crystalline silicon solar cells
Authors: da Silva D. S. , Côrtes A. D. S. , Oliveira M. H. , Motta E. F. , Viana G. A. , Mei P. R. , Marques F. C.
Published: August 2011

We report on the investigation of the potential application of different forms of amorphous carbon (a-C and a-C:H) as an antireflective coating for crystalline silicon solar cells. Polymeric-like carbon (PLC) and hydrogenated diamond-like carbon films were deposited by plasma enhanced chemical vapor deposition. Tetrahedral amorphous carbon (ta-C) was deposited by the filtered cathodic vacuum arc technique. Those three different amorphous carbon structures were individually applied as single antireflective coatings on conventional (polished and texturized) p-n junction crystalline silicon solar cells. Due to their optical properties, good results were also obtained for double-layer antireflective coatings based on PLC or ta-C films combined with different materials. The results are compared with a conventional tin dioxide (SnO2) single-layer antireflective coating and zinc sulfide/magnesium fluoride (ZnS/MgF2) double-layer antireflective coatings. An increase of 23.7% in the short-circuit current density, Jsc, was obtained using PLC as an antireflective coating and 31.7% was achieved using a double-layer of PLC with a layer of magnesium fluoride (MgF2). An additional increase of 10.8% was obtained in texturized silicon, representing a total increase (texturization + double-layer) of about 40% in the short-circuit current density. The potential use of these materials are critically addressed considering their refractive index, optical bandgap, absorption coefficient, hardness, chemical inertness, and mechanical stability.
A wide-angle planar metamaterial absorber based on split ring resonator coupling
Authors: Qiu Xu Yang , Heng Zhou Pei , Bin Zhang Hui , Chen Liang , Jiang Deng Long
Published: August 2011

A wide-angle planar metamaterial structure exhibiting strong absorption is presented. The structure functions as a near-perfect absorber with the incident electric field propagating not only across but also along the gaps of individual split ring resonator (SRR) elements. It is the coupling of adjacent SRRs that provides capacitance necessary to excite the LC resonance for absorption. Both simulations and experiments are shown in this paper. The experimental results indicate that when the electric field propagates along the gaps of individual SRR elements, the structure obtains 1.6-GHz-wide absorption with absorptivity larger than 90% at small incident angles. The proposed structure offers a potential way to create azimuth-independent broadband metamaterial absorber.
Rayleigh–Bénard convection: Improved bounds on the Nusselt number
Authors: Otto Felix , Seis Christian
Published: August 2011

We consider Rayleigh–Bénard convection as modelled by the Boussinesq equations in the infinite-Prandtl-number limit. We are interested in the scaling of the average upward heat transport, the Nusselt number Nu, in terms of the non-dimensionalized temperature forcing, the Rayleigh number Ra. Experiments, asymptotics and heuristics suggest that Nu ∼ Ra1/3. This work is mostly inspired by two earlier rigorous work on upper bounds of Nu in terms of Ra. (1) The work of Constantin and Doering establishing Nu ≲ Ra1/3ln 2/3Ra with help of a (logarithmically failing) maximal regularity estimate in L∞ on the level of the Stokes equation. (2) The work of Doering, Reznikoff and the first author establishing Nu ≲ Ra1/3ln 1/3Ra with help of the background field method. The paper contains two results. (1) The background field method can be slightly modified to yield Nu ≲ Ra1/3ln 1/15Ra. (2) The estimates behind the background field method can be combined with the maximal regularity in L∞ to yield Nu ≲ Ra1/3ln 1/3ln Ra — an estimate that is only a double logarithm away from the supposedly optimal scaling.
High-quality 1.3 μm-wavelength GaInAsN/GaAs quantum wells grown by metalorganic vapor phase epitaxy on vicinal substrates
Authors: Fekete D. , Carron R. , Gallo P. , Dwir B. , Rudra A. , Kapon E.
Published: August 2011

We investigated the composition and optical properties of GaInAsN/GaAs single quantum wells (QWs) grown on vicinal-(001) GaAs substrates using metallorganic vapor phase epitaxy with modulated nitrogen-precursor flux. A significant enhancement in N incorporation and photoluminescence efficiency is achieved with such optimized QW structures. Possible mechanisms of the observed increase in N uptake and reduction in defect density, related to the substrate vicinality, are discussed.
Solar coronal loops as non force-free minimum energy relaxed states
Authors: Kumar Dinesh , Bhattacharyya R.
Published: August 2011

In this work, the well established two-fluid relaxation model based on the minimum energy principle is extended to include open systems like the solar corona. The Euler-Lagrange equations obtained are of double curl in nature and support non-zero plasma-β along with mass flow of the magnetofluid. These equations are solved in Cartesian coordinates utilizing a geometry relevant to the solar atmosphere, and a basic comparative study of the non force-free, force-free, and potential magnetic field obtained as solutions of the same Euler-Lagrange equations is presented.
Quasisymmetric toroidal plasmas with large mean flows
Authors: Sugama H. , Watanabe T.-H. , Nunami M. , Nishimura S.
Published: August 2011

Geometric conditions for quasisymmetric toroidal plasmas with large mean flows on the order of the ion thermal speed are investigated. Equilibrium momentum balance equations including the inertia term due to the large flow velocity are used to show that, for rotating quasisymmetric plasmas with no local currents crossing flux surfaces, all components of the metric tensor should be independent of the toroidal angle in the Boozer coordinates, and consequently these systems need to be rigorously axisymmetric. Unless the local radial currents vanish, the Boozer coordinates do not exist and the toroidal flow velocity cannot take any value other than a very limited class of eigenvalues corresponding to very rapid rotation especially for low beta plasmas.
Combined influence of streaming potential and substrate compliance on load capacity of a planar slider bearing
Authors: Chakraborty Jeevanjyoti , Chakraborty Suman
Published: August 2011

In the present study, we investigate the combined interplay of streaming potential and substrate compliance with sliding dynamics on the load carrying capacity of a planar slider bearing. We relax previously utilized simplifying assumptions to model the electrokinetic effects and demonstrate that the streaming potential may augment the load carrying capacity of the bearing to a considerable extent. Interestingly, we also reveal that the electrokinetically augmented load carrying capacity exhibits strong dependencies on a combination of the compliance and the sliding dynamics, which have, hitherto, not been extensively explored. This rich interplay reveals certain parametric regimes of interest, which are significant from the viewpoint of practical design considerations.
Bipolaron recombination in conjugated polymers
Authors: Sun Zhen , Stafström Sven
Published: August 2011

By using the Su-Schrieffer-Heeger model modified to include electron-electron interactions, the Brazovskii-Kirova symmetry breaking term and an external electric field, we investigate the scattering process between a negative and a positive bipolaron in a system composed of two coupled polymer chains. Our results show that the Coulomb interactions do not favor the bipolaron recombination. In the region of weak Coulomb interactions, the two bipolarons recombine into a localized excited state, while in the region of strong Coulomb interactions they can not recombine. Our calculations show that there are mainly four channels for the bipolaron recombination reaction: (1) forming a biexciton, (2) forming an excited negative polaron and a free hole, (3) forming an excited positive polaron and a free electron, (4) forming an exciton, a free electron, and a free hole. The yields for the four channels are also calculated.
Structural basis for supercooled liquid fragility established by synchrotron-radiation method and computer simulation
Authors: Louzguine-Luzgin D. V. , Belosludov R. , Yavari A. R. , Georgarakis K. , Vaughan G. , Kawazoe Y. , Egami T. , Inoue A.
Published: August 2011

Metallic melts above the liquidus temperature exhibit nearly Arrhenius-type temperature dependence of viscosity. On cooling below the equilibrium liquidus temperature metallic melts exhibit a non-Arrhenius temperature dependence of viscosity characterized by liquid fragility phenomenon which origin is still not well understood. Structural changes and vitrification of the Pd42.5Cu30Ni7.5P20 liquid alloy on cooling from above the equilibrium liquidus temperature are studied by synchrotron radiation X-ray diffraction and compared with the results of first-principles calculations. Subsequent analysis of the atomic and electronic structure of the alloy in liquid and glassy states reveals formation of chemical short-range order in the temperature range corresponding to such a non-Arrhenius behavior. The first-principles calculations were applied to confirm the experimental findings.
Thermodynamic scaling of polymer dynamics versus T – Tg scaling
Authors: Guo Jiaxi , Simon Sindee L.
Published: August 2011

A thermodynamic scaling law for the relaxation times of complex liquids as a function of temperature and volume has been proposed in the literature: τ(T,V) = ƒ(TVγ), where γ is a material-dependent constant. We test this scaling for six materials, linear polystyrene, star polystyrene, two polycyanurate networks, poly(vinyl acetate), and poly(vinyl chloride), and compare the thermodynamic scaling to T – Tg scaling, where τ = ƒ(T – Tg). The thermodynamic scaling law successfully reduces the data for all of the samples; however, polymers with similar structures but different glass transition (Tg) and pressure-volume-temperature (PVT) behavior, i.e., the two polycyanurates, cannot be superposed unless the scaling law is normalized by TgVgγ. On the other hand, the T – Tg scaling successfully reduced data for all polymers, including those having similar microstructures. In addition, the T – Tg scaling is easier to implement since it does not require knowledge of the PVT behavior of the material. The relationship between TgVgγ/TVγ and T – Tg scaling is clarified and is found to be weakly dependent on pressure.
Femtosecond study of ultrafast fluorescence resonance energy transfer in a catanionic vesicle
Authors: Kumar Das Atanu , Mondal Tridib , Kumar Sasmal Dibyendu , Bhattacharyya Kankan
Published: August 2011

Ultrafast fluorescence resonance energy transfer (FRET) in a catanionic [sodium dodecyl sulfate (SDS)-dodecyltrimethyl ammonium bromide (DTAB)] vesicle is studied by femtosecond up-conversion. The vesicles (diameter ∼400 nm for SDS-rich and ∼250 nm for DTAB-rich vesicles) are much larger than the SDS and DTAB micelles (diameter ∼4 nm). In both micelle and vesicles, FRET occurs in multiple time scales and the time scales of FRET correspond to a donor-acceptor distance varying between 12 and 36 Å.
Note: Miniature 120-kV autonomous generator based on transverse shock-wave depolarization of Pb(Zr0.52Ti0.48)O3 ferroelectrics
Authors: Shkuratov Sergey I. , Baird Jason , Talantsev Evgueni F.
Published: August 2011

The design of autonomous ultrahigh-voltage generators with no moving metallic parts based on transverse explosive shock wave depolarization of Pb(Zr0.52Ti0.48)O3 (PZT 52/48) poled ferroelectrics was explored and studied. It follows from experimental results that the output voltage produced by the shock-wave ferroelectric generators (FEGs) is directly proportional to the number of PZT 52/48 elements connected in series. It was demonstrated that miniature FEGs (volume less than 180 cm3) were capable of reliably producing output voltage pulses with amplitudes exceeding 120 kV which is the record reported in open literature.
Structural and optical characterization of type-II InAs/InAs1−xSbx superlattices grown by metalorganic chemical vapor deposition
Authors: Steenbergen E. H. , Huang Y. , Ryou J.-H. , Ouyang L. , Li J.-J. , Smith D. J. , Dupuis R. D. , Zhang Y.-H.
Published: August 2011

Strain-balanced type-II InAs/InAs1–xSbx superlattices with various compositions (x = 0.22, 0.23, 0.37) and different layer thicknesses (tInAs = 7 nm, tInAsSb = 3.3, 2.3, 2.0 nm, respectively) have been grown by metalorganic chemical vapor deposition on GaSb substrates. X-ray diffraction revealed narrow satellite peaks (full-width-half-maximum of <100 arc sec), indicative of uniform superlattice periodicity and excellent crystallinity, which was also corroborated by cross-sectional transmission electron microscopy observations. Despite relaxation, low-temperature photoluminescence measurements showed peaks at 6.7 μm and 5.8 μm, while photoconductance results showed strong spectral response up to 200 K, when the photoresponse onset was 8.6 μm.
Segregation of hydroxide ions to an ice surface
Authors: Kim Sooyeon , Park Eunhee , Kang Heon
Published: August 2011

Hydroxide ions that are initially buried within an ice film segregate to the ice film surface at elevated temperatures. This process was observed by conducting experiments with an ice film constructed with a bottom H2O layer and an upper D2O layer, with an excess of hydroxide ions trapped at the H2O/D2O interface as they were generated by Na hydrolysis. The transport of hydroxide ions from the interfacial layer to the surface was examined as a function of time using a low energy sputtering method. The progress of the H/D exchange reaction in surface water molecules was also monitored with the Cs+ reactive ion scattering technique. At 90 K, only a small portion of buried hydroxide ions moved to the surface in the form of OD− species. This was due to hydroxide transport via proton hopping through a D2O layer, 3 BL thick, in the surface region. At 135 K, at which point water self-diffusion is active in the ice film, the majority of the buried hydroxide ions segregated to the surface after ∼1 h. Both OH− and OD− species were produced at the surface, at an OH−/OD− population ratio ≥1. Based on kinetic measurements for the transport of OH− and OD− species and the H/D exchange of surface water molecules, we concluded that the major transport channel for hydroxide ions in this regime is the migration of molecular hydroxide species. H/D exchange reactions also occur between surface hydroxide ions and water molecules. No evidence was observed for the occurrence of the hop-and-turn process at 135 K, although it is known as an important mechanism of proton transport in ice.
The influence of dopant type and carrier concentration on the effective mass and Seebeck coefficient of GaNxAs1−x thin films
Authors: Pichanusakorn P. , Kuang Y. J. , Patel C. J. , Tu C. W. , Bandaru P. R.
Published: August 2011

We probe whether an enhancement in the Seebeck coefficient (S) could be obtained in GaNxAs1−x through interactions between the N resonant states and the GaAs conduction band. Through experimental investigations, we then determined that an insufficient increase in the density of states effective mass (md) precludes such an enhancement. The relative influences of Group IV/VI dopants and the carrier concentration along with N passivation are discussed.
Structure determination of the nonlinear hydrocarbon chains C9H3 and C11H3 by deuterium labeling
Authors: Zhao Dongfeng , Ali Haddad Mohammad , Linnartz Harold , Ubachs Wim
Published: August 2011

A systematic deuterium labeling experiment is presented that aims at an unambiguous determination of the geometrical ground state structure of the C9H3 and C11H3 hydrocarbon chains. Cavity ring-down spectroscopy and special plasma expansions constituting C/H, C/D, and C/H/D are used to record optical transitions of both species and their (partially) deuterated equivalents in the 19 000 cm−1 region. The number of observed bands, the quantitative determination of isotopic shifts, and supporting calculations show that the observed C9H3 and C11H3 spectra originate from HC4(CH)C4H and HC4[C(C2H)]C4H species with C2v symmetry. This result illustrates the potential of deuterium labeling as a useful approach to characterize the molecular structure of nonlinear hydrocarbon chains.
Color tunable light-emitting diodes based on copper doped semiconducting nanocrystals
Authors: Bhaumik Saikat , Ghosh Batu , Pal Amlan J.
Published: August 2011

We have introduced copper-doped semiconducting nanocrystals in light-emitting diodes (LEDs). Characteristics of the devices show that electroluminescence (EL) emission in these LEDs is color tunable. In copper-doped ZnS nanocrystals in the core and Zn1−xCdxS host as a shell-layer, photoluminescence (PL) arises from a transition from conduction band-edge of the host to 3d-levels of copper-ions. The PL of the nanocrystals and hence the EL of LEDs based on such nanostructures become tunable by varying the Cd-content in Zn-Cd-S alloys, that is, Zn1−xCdxS with different values of x, which changes the conduction band-edge of the host.
Generalized synchronization-based multiparameter estimation in modulated time-delayed systems
Authors: Ghosh Dibakar , Bhattacharyya Bidyut K.
Published: August 2011

We propose a nonlinear active observer based generalized synchronization scheme for multiparameter estimation in time-delayed systems with periodic time delay. A sufficient condition for parameter estimation is derived using Krasovskii-Lyapunov theory. The suggested tool proves to be globally and asymptotically stable by means of Krasovskii-Lyapunov method. With this effective method, parameter identification and generalized synchronization of modulated time-delayed systems with all the system parameters unknown, can be achieved simultaneously. We restrict our study for multiple parameter estimation in modulated time-delayed systems with single state variable only. Theoretical proof and numerical simulation demonstrate the effectiveness and feasibility of the proposed technique. The block diagram of electronic circuit for multiple time delay system shows that the method is easily applicable in practical communication problems.
Step driven competitive epitaxial and self-limited growth of graphene on copper surface
Authors: Fan Lili , Li Zhen , Xu Zhiping , Wang Kunlin , Wei Jinquan , Li Xiao , Zou Jie , Wu Dehai , Zhu Hongwei
Published: August 2011

The existence of surface steps was found to have significant function and influence on the growth of graphene on copper via chemical vapor deposition. The two typical growth modes involved were found to be influenced by the step morphologies on copper surface, which led to our proposed step driven competitive growth mechanism. We also discovered a protective role of graphene in preserving steps on copper surface. Our results showed that wide and high steps promoted epitaxial growth and yielded multilayer graphene domains with regular shape, while dense and low steps favored self-limited growth and led to large-area monolayer graphene films. We have demonstrated that controllable growth of graphene domains of specific shape and large-area continuous graphene films are feasible.
Photochemical Methods for the Preparation of Complex Linear and Cross-linked Macromolecular Structures
Authors: Tasdelen Mehmet Atilla , Yagci Yusuf
Published: August 2011

In this contribution, the current state of the art is summarized and an overview of photoinitiating systems for both radical and cationic polymerizations and their potential application in the preparation of complex linear and cross-linked macromolecular structures are described. Recent relevant studies have been devoted to developing novel free radical and cationic photoinitiators having spectroscopic sensitivity in the near-UV or visible range. Photoinitiated controlled radical polymerization methods leading to tailor-made polymers with predetermined structure and architecture are briefly presented. Several synthetic methodologies for the preparation of epoxy and (meth)acrylate based formulations containing clay or metal nanoparticles are also summarized. The nanoparticles are homogenously distributed in the network without macroscopic agglomeration. Applicability to both free radical and cationic systems is demonstrated.
Synthesis of Acyclic, Symmetrical 3,3'-Allyl Dithioethers, from the Alkylation of 3-Mercapto-2-mercaptomethylprop-1-ene in the Presence of Sodium Hydride
Authors: Moorhoff Cornelis M. , Cook Wayne D. , Chen Fei , Nghiem Dat , Braybrook Carl , Thang San H. , Sun Jiazeng , Scott Timothy F. , Bowman Christopher N.
Published: August 2011

A novel method where 3,3′-allyl dithioethers have been prepared from 3-mercapto-2-mercaptomethylprop-1-ene and two mol equivalent of alkyl halide in the presence of two mol equivalent of sodium hydride has been developed. Using this method, bisepoxide, 2,2′-(2-methylenepropane-1,3-diyl)bis(sulfanediyl)bis(methylene)dioxirane (8) has been synthesized from epichlorohydrin, whereas potassium carbonate was unable to deliver this product. These 3,3′-allyl dithioethers can be utilized either as monomers, or with further chemical reactions transformed into more complex monomers, for photoplastic polymer networks.