bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impact of Effort–Reward Imbalance and Learning Motivation on Teachers' Sickness Absence
Authors: Derycke Hanne , Vlerick Peter , Van de Ven Bart , Rots Isabel , Clays Els
Published: February 2012

The aim of this study was to analyse the impact of the effort–reward imbalance and learning motivation on sickness absence duration and sickness absence frequency among beginning teachers in Flanders (Belgium).

A total of 603 teachers, who recently graduated, participated in this study. Effort–reward imbalance and learning motivation were assessed by means of self‐administered questionnaires. Prospective data of registered sickness absence during 12 months follow‐up were collected. Multivariate logistic regression analyses were performed.

An imbalance between high efforts and low rewards (extrinsic hypothesis) was associated with longer sickness absence duration and more frequent absences. A low level of learning motivation (intrinsic hypothesis) was not associated with longer sickness absence duration but was significantly positively associated with sickness absence frequency. No significant results were obtained for the interaction hypothesis between imbalance and learning motivation. Further research is needed to deepen our understanding of the impact of psychosocial work conditions and personal resources on both sickness absence duration and frequency. Specifically, attention could be given to optimizing or reducing efforts spent at work, increasing rewards and stimulating learning motivation to influence sickness absence. Copyright © 2012 John Wiley & Sons, Ltd.
The temporal effects of relative and firm‐level absorptive capacity on interorganizational learning
Authors: Schildt Henri , Keil Thomas , Maula Markku
Published: February 2012

We examine how determinants of absorptive capacity influence learning in alliances over time. Using longitudinal patent cross‐citation data, we find an inverted U‐shaped pattern over time that is influenced by firm‐level and relational factors. Technological similarity only modestly increases learning in the initial stages of a relationship, but moderate levels substantially increase knowledge flows later in the alliance. High technological diversity is related to higher initial learning rates, but the effects diminish over time. Somewhat surprisingly, research and development intensity is negatively related to initial learning rates but has a considerable positive effect later in the relationship. We suggest that initial learning rates in alliances may be constrained by the capacity to absorb knowledge, while later‐stage outcomes are constrained by exploitation capacity. Copyright © 2012 John Wiley & Sons, Ltd.
Upregulation of dysbindin in temporal lobe epileptic foci of human and experimental animals
Authors: Zhang Ying , Xu Yali , Zhu Qiong , Zhao Fenghua , Luo Jing , Zhang Xiaogang , Wang Xuefeng
Published: February 2012

The gene encoding dystrobrevin‐binding‐protein‐1 (dysbindin) is expressed in many areas of the central nervous system and plays a role in intracellular vesicle trafficking, synaptic vesicle trafficking, and neurotransmitter release. At a cellular level, dysbindin is thought to mediate presynaptic glutamatergic transmission. Using Western blotting and immunofluorescence, we investigated dysbindin expression in brain tissues of the patients with temporal lobe epilepsy (TLE) and rats with TLE (lithium chloride pilocarpine model) to explore its possible role in epileptogenesis. Twenty‐five samples of temporal neocortex from patients undergoing surgery for drug‐refractory TLE epilepsy and 10 histologically normal temporal lobes tissues from control subjects were used in our study. We also examined dysbindin expression in the hippocampus and adjacent cortex from experimental Sprague–Dawley rats. Dysbindin was expressed in the cytoplasm of neurons from epileptic specimens, and levels of dysbindin proteins were significantly increased in patients with TLE. Dysbindin was also expressed in the neurons of the hippocampus and adjacent cortex from experimental and control rats. Western blotting of rat brain tissue showed that dysbindin was upregulated gradually from 6 h after kindling. Maximal expression was seen around 2 months in chronic epileptic phase. These results demonstrated that the increased expression of dysbindin might play a role in the pathogenesis of drug‐refractory TLE. Synapse, 2012. © 2012 Wiley Periodicals, Inc.
Metabolomics methods for the synthetic biology of secondary metabolism
Authors: Nguyen Quoc-Thai , Merlo Maria E. , Medema Marnix H. , Jankevics Andris , Breitling Rainer , Takano Eriko
Published: February 2012

Many microbial secondary metabolites are of high biotechnological value for medicine, agriculture, and the food industry. Bacterial genome mining has revealed numerous novel secondary metabolite biosynthetic gene clusters, which encode the potential to synthesize a large diversity of compounds that have never been observed before. The stimulation or “awakening” of this cryptic microbial secondary metabolism has naturally attracted the attention of synthetic microbiologists, who exploit recent advances in DNA sequencing and synthesis to achieve unprecedented control over metabolic pathways. One of the indispensable tools in the synthetic biology toolbox is metabolomics, the global quantification of small biomolecules. This review illustrates the pivotal role of metabolomics for the synthetic microbiology of secondary metabolism, including its crucial role in novel compound discovery in microbes, the examination of side products of engineered metabolic pathways, as well as the identification of major bottlenecks for the overproduction of compounds of interest, especially in combination with metabolic modeling. We conclude by highlighting remaining challenges and recent technological advances that will drive metabolomics towards fulfilling its potential as a cornerstone technology of synthetic microbiology.
The influence of size, specific gravity, and head position on the swallowing of solid preparations
Authors: Kasashi Kumiko , Tei Kanchu , Totsuka Yasunori , Yamada Takehiro , Iseki Ken
Published: February 2012

Aim: To clarify the influence of size and specific gravity of solid preparations, and the position of healthy volunteers when swallowing, for the purpose of practical use in patient consultation regarding the taking of medicines.

Materials and methods: The paper reports three studies. Volunteers were asked to swallow four different capsules (A, large and heavy; B, large and light; C, small and heavy; D, small and light) in Study 1, two preparations with different positions (upright, horizontal, and chin‐down) in Study 2, and two preparations before and after anesthetization of the bilateral lingual and inferior alveolar nerve in Study 3. The oral transit time (OTT) and pharyngeal transit time (PTT) were evaluated with videofluoroscopy.

Results: The mean OTT became longer in the order of C, D, B, A. The mean PTT showed no statistically significant differences. The swallowing preference of the four preparations ranked by the subjects showed that difference in size but not the difference in specific gravity is a significant factor. In the chin‐down position, OTT was shorter for two preparations, compared with the other two positions. The mean OTT for both the A and B preparations was significantly longer after the bilateral lingual and inferior alveolar nerves were anesthetized.

Conclusion: When swallowing solid preparations, a consideration of size and the position will enable ease of swallowing of medicines. This would especially be the case when delivery of the medicines to be taken by the aged suffering from oral hypoesthesia caused by an underlying disease.
Rhazes in the Renaissance of Andreas Vesalius
Authors: Compier Abdul Haq
Published: February 2012

Andreas Vesalius' (1514–64) first publication was a Paraphrasis of the ninth book of the Liber ad Almansorem, written by the Arab–Persian physician and alchemist Rhazes (854–925). The role of Rhazes in Vesalius' oeuvre has thus far been much disregarded. The different ways Rhazes recurs reveal an intellectual evolution in Vesalius' work. In the Paraphrasis, Vesalius subjects Rhazes to the authority of Galen in the context of the early sixteenth-century humanist campaign for the substitution of Arab influences by Greek ‘originals’. Over the years Vesalius continues his work on Rhazes, but his approach becomes more internationalistic. Ultimately, Vesalius criticises Galen while expressing sympathy for the Arab author. This may be the more significant as Rhazes could have influenced Vesalius in the act of criticising Galen – critical discussions of Galen were available to Vesalius in Latin translations of Rhazes's Liber Continens. Although Vesalius never refers to the work, it is hardly possible he was unaware of it: similarities in structure, rhetoric and form between the Continens and the De humani corporis fabrica could support this hypothesis.
‘By Merit Raised to That Bad Eminence’: Christopher Merrett, Artisanal Knowledge, and Professional Reform in Restoration London
Authors: Mauck Aaron
Published: February 2012

This article examines the career and reform agenda of Christopher Merrett as a means of evaluating the changing conditions of medical knowledge production in late seventeenth-century London. This period was characterised by increasing competition between medical practitioners, resulting from the growing consumer demand for medical commodities and services, the reduced ability of elite physicians to control medical practice, and the appearance of alternative methods of producing medical knowledge – particularly experimental methods. This competition resulted in heated exchanges between physicians, apothecaries, and virtuosi, in which Merrett played an active part. As a prominent member of both the Royal Society and the Royal College of Physicians, Merrett sought to mediate between the two institutions by introducing professional reforms designed to alleviate competition and improve medical knowledge.These reforms entailed sweeping changes to medical regulation and education that integrated the traditional reliance on Galenic principles with knowledge derived from experiment and artisanal practices. The emphasis Merrett placed on the trades suggests the important role artisanal knowledge played in his efforts to reorganise medicine and improve knowledge of bodily processes.
Explaining Local Authority Choices on Public Hospital Provision in the 1930s: A Public Policy Hypothesis
Authors: Neville Julia
Published: February 2012

This article summarises the findings of recent work on local authority public hospital services in England and Wales in the inter-war years and identifies the lack of a robust hypothesis to explain the variations found, particularly one that would explain the actions of county councils as well as county boroughs. Using public policy techniques on a group of local authorities in the far South West it proposes that variations can be explained by an understanding of the deep core beliefs of councillors, their previous experience of ‘commissioner’ and ‘provider’ roles, and the availability or otherwise of a dedicated policy entrepreneur to promote change.
Empiric Management of Cyanide Toxicity Associated with Smoke Inhalation
Authors: O’Brien Daniel J. , Walsh Donald W. , Terriff Colleen M. , Hall Alan H.
Published: February 2012

Enclosed-space smoke inhalation is the fifth most common cause of all unintentional injury deaths in the United States. Increasingly, cyanide has been recognized as a significant toxicant in many cases of smoke inhalation. However, it cannot be emergently verified. Failure to recognize the possibility of cyanide toxicity may result in inadequate treatment. Findings suggestive cyanide toxicity include: (1) a history of an enclosed-space fire scene in which smoke inhalation was likely; (2) the presence of oropharyngeal soot or carbonaceous expectorations; (3) any alteration of the level of consciousness, and particularly, otherwise inexplicable hypotension (systolic blood pressure ≤90 mmHg in adults). Prehospital studies have demonstrated the feasibility and safety of empiric treatment with hydroxocobalamin for patients with suspected smoke inhalation cyanide toxicity. Although United States Food and Drug Administration (FDA)-approved since 2006, the lack of efficacy data has stymied the routine use of this potentially lifesaving antidote. Based on a literature review and on-site observation of the Paris Fire Brigade, emergency management protocols to guide empiric and early hydroxocobalamin administration in smoke inhalation victims with high-risk presentations are proposed.
A Second Case Report of Lleuprolide Acetate for Depot Suspension-Induced Mania
Authors: Wahi Monika M. , Skeate Robert C. , Goldin Steven B. , Santana Carlos A.
Published: February 2012

This is the second published case report of Lleuprolide acetate for depot suspension (LD)-induced mania. Both reports detail a patient with a prior psychiatric history of both depressive and hypomanic episodes. While depression is a predictable and documented side effect of LD and menopause (especially in those with a previous
history of symptoms), manic reactions are rare and unexplained. Possible causative mechanisms
behind the LD-induced manic episodes are discussed, and we suggest that patients with a single previous hypomanic episode are at risk for LD-induced mania.
Seasonal and clock angle control of the location of flux transfer event signatures at the magnetopause
Authors: Fear R. C. , Palmroth M. , Milan S. E.
Published: February 2012

Most models of flux transfer event (FTE) formation produce pairs of structures which in general move away from the subsolar region and give rise to signatures which can be observed in both the Northern and Southern Hemispheres. The multiple reconnection line (X line) model is unusual as a reconnection‐based model that is capable of producing a single flux rope if only two X lines are present. Raeder (2006) reported the results of an MHD simulation where he studied the effect of the Earth's dipole tilt on reconnection at the dayside magnetopause for a southward IMF orientation; in his simulations, flux ropes were formed by the sequential formation of X lines, and when the dipole tilt was set to a value representative of solstice the flux ropes moved preferentially toward the winter hemisphere. Some observational evidence has previously been presented for a bias toward FTE signatures being observed in the winter hemisphere; in this paper, we present further observational evidence for this phenomenon, using an independently derived data set. Once the seasonal bias is taken into account, we find that the IMF clock angle controls the location of FTE signatures. We also find that the effective dipole tilt (combining the geomagnetic dipole tilt with the IMF tilt angle) provides no clear control of the location of FTE signatures.
Observations of inorganic bromine (HOBr, BrO, and Br2) speciation at Barrow, Alaska, in spring 2009
Authors: Liao J. , Huey L. G. , Tanner D. J. , Flocke F. M. , Orlando J. J. , Neuman J. A. , Nowak J. B. , Weinheimer A. J. , Hall S. R. , Smith J. N. , Fried A. , Staebler R. M. , Wang Y. , Koo J.‐H. , Cantrell C. A. , Weibring P. , Walega J. , Knapp D. J. , Shepson P. B. , Stephens C. R.
Published: February 2012

Inorganic bromine plays a critical role in ozone and mercury depletions events (ODEs and MDEs) in the Arctic marine boundary layer. Direct observations of bromine species other than bromine oxide (BrO) during ODEs are very limited. Here we report the first direct measurements of hypobromous acid (HOBr) as well as observations of BrO and molecular bromine (Br2) by chemical ionization mass spectrometry at Barrow, Alaska in spring 2009 during the Ocean‐Atmospheric‐Sea Ice‐Snowpack (OASIS) campaign. Diurnal profiles of HOBr with maximum concentrations near local noon and no significant concentrations at night were observed. The measured average daytime HOBr mixing ratio was 10 pptv with a maximum value of 26 pptv. The observed HOBr was reasonably well correlated (R2 = 0.57) with predictions from a simple steady state photochemical model constrained to observed BrO and HO2 at wind speeds <6 m s−1. However, predicted HOBr levels were considerably higher than observations at higher wind speeds. This may be due to enhanced heterogeneous loss of HOBr on blowing snow coincident with higher wind speeds. BrO levels were also found to be higher at elevated wind speeds. Br2 was observed in significant mixing ratios (maximum = 46 pptv; average = 13 pptv) at night and was strongly anti‐correlated with ozone. The diurnal speciation of observed gas phase inorganic bromine species can be predicted by a time‐dependent box model that includes efficient heterogeneous recycling of HOBr, hydrogen bromide (HBr), and bromine nitrate (BrONO2) back to more reactive forms of bromine.
Guanine Nucleotide-Binding Protein Gαi2: A New Partner of Claudin-5 that Regulates Tight Junction Integrity in Human Brain Endothelial Cells
Authors: Luissint Anny-Claude , Federici Christian , Guillonneau François , Chrétien Fabrice , Camoin Luc , Glacial Fabienne , Ganeshamoorthy Kayathiri , Couraud Pierre-Olivier
Published: February 2012

The blood—brain barrier (BBB) selectively controls the exchanges between the blood and the brain: it is formed by tight junctions (TJs) between adjacent microvascular endothelial cells. The transmembrane protein claudin-5 is known as a key TJ protein at the BBB, although, the molecular mechanisms by which it regulates TJ tightness are poorly understood. To identify putative claudin-5 partners that contribute to TJ integrity, claudin-5-enriched membrane microdomains were prepared by cell fractionation, using the human brain endothelial cell line hCMEC/D3 and claudin-5 immunoprecipitates were submitted to tandem mass spectrometry. Because a high concentration of mannitol is known to transiently destabilize TJs, this analysis was performed in basal conditions, after mannitol treatment, and after recovery of TJ integrity. We here demonstrate that the G-protein subunit αi2 (Gαi2) interacts with claudin-5 and that association is correlated with TJ integrity in hCMEC/D3 cells; also, a selective expression of Gαi2 is observed in human brain vasculature in situ. Moreover, small interfering RNA-mediated depletion of Gαi2 or claudin-5 in hCMEC/D3 cells similarly increases their paracellular permeability and delays TJ recovery after mannitol treatment. Altogether, our results identify Gαi2 as a novel claudin-5 partner required for TJ integrity in brain endothelial cells.
Wall-loss distribution of charge breeding ions in an electron cyclotron resonance ion source
Authors: Jeong S. C. , Oyaizu M. , Imai N. , Hirayama Y. , Ishiyama H. , Miyatake H. , Niki K. , Okada M. , Watanabe Y. X. , Otokawa Y. , Osa A. , Ichikawa S.
Published: February 2012

We investigated the ion-loss distribution on the sidewall of an electron cyclotron resonance (ECR) plasma chamber using the 18-GHz ECR charge breeder at the Tokai Radioactive Ion Accelerator Complex (TRIAC). Similarities and differences between the ion-loss distributions (longitudinal and azimuthal) of different ion species (i.e., radioactive 111In1+ and 140Xe1+ ions that are typical volatile and nonvolatile elements) was qualitatively discussed to understand the element dependence of the charge breeding efficiency. Especially, the similarities represent universal ion loss characteristics in an ECR charge breeder, which are different from the loss patterns of electrons on the ECRIS wall.
Status of ion sources at National Institute of Radiological Sciences
Authors: Kitagawa A. , Fujita T. , Goto A. , Hattori T. , Hamano T. , Hojo S. , Honma T. , Imaseki H. , Katagiri K. , Muramatsu M. , Sakamoto Y. , Sekiguchi M. , Suda M. , Sugiura A. , Suya N.
Published: February 2012

The National Institute of Radiological Sciences (NIRS) maintains various ion accelerators in order to study the effects of radiation of the human body and medical uses of radiation. Two electrostatic tandem accelerators and three cyclotrons delivered by commercial companies have offered various life science tools; these include proton-induced x-ray emission analysis (PIXE), micro beam irradiation, neutron exposure, and radioisotope tracers and probes. A duoplasmatron, a multicusp ion source, a penning ion source (PIG), and an electron cyclotron resonance ion source (ECRIS) are in operation for these purposes. The Heavy-Ion Medical Accelerator in Chiba (HIMAC) is an accelerator complex for heavy-ion radiotherapy, fully developed by NIRS. HIMAC is utilized not only for daily treatment with the carbon beam but also for fundamental experiments. Several ECRISs and a PIG at HIMAC satisfy various research and clinical requirements.
Development of high current Bi and Au beams for the synchrotron operation at the GSI accelerator facility
Authors: Adonin A. , Hollinger R.
Published: February 2012

In this work, the latest results of developing high current ion beams of Au and Bi at GSI facility are described. The difficulties in the production of required charge state in vacuum arc discharge ion sources using the pure materials in the cathodes are discussed. As a possible solution, admix of a small amount of more refractory metal to the cathode material is considered. As a significant result, a dramatic improvement in the production of high charge state Bi ions using the mixed Bi-Cu cathodes (with 8%–15% of Cu admixed) compared to pure Bi cathodes is presented. The preliminary results of investigation of the material structure of Bi-Cu cathodes are discussed. As a next step, it is planned to test the composition of Au with Pd, Zr, and Fe as cathode materials.
Novel methods for improvement of a Penning ion source for neutron generator applications
Authors: Sy A. , Ji Q. , Persaud A. , Waldmann O. , Schenkel T.
Published: February 2012

Penning ion source performance for neutron generator applications is characterized by the atomic ion fraction and beam current density, providing two paths by which source performance can be improved for increased neutron yields. We have fabricated a Penning ion source to investigate novel methods for improving source performance, including optimization of wall materials and electrode geometry, advanced magnetic confinement, and integration of field emitter arrays for electron injection. Effects of several electrode geometries on discharge characteristics and extracted ion current were studied. Additional magnetic confinement resulted in a factor of two increase in beam current density. First results indicate unchanged proton fraction and increased beam current density due to electron injection from carbon nanofiber arrays.
New ion source for KSTAR neutral beam injection system
Authors: Kim Tae-Seong , Jeong Seung Ho , In Sang-Ryul
Published: February 2012

The neutral beam injection system (NBI-1) of the KSTAR tokamak can accommodate three ion sources; however, it is currently equipped with only one prototype ion source. In the 2010 and 2011 KSTAR campaigns, this ion source supplied deuterium neutral beam power of 0.7–1.6 MW to the KSTAR plasma with a beam energy of 70–100 keV. A new ion source will be prepared for the 2012 KSTAR campaign with a much advanced performance compared with the previous one. The newly designed ion source has a very large transparency (∼56%) without deteriorating the beam optics, which is designed to deliver a 2 MW injection power of deuterium beams at 100 keV. The plasma generator of the ion source is of a horizontally cusped bucket type, and the whole inner wall, except the cathode filaments and plasma grid side, functions as an anode. The accelerator assembly consists of four multi-circular aperture grids made of copper and four electrode flanges made of aluminum alloy. The electrodes are insulated using PEEK. The ion source will be completed and tested in 2011.
Micromagnetic studies on resolution limits of magnetic force microscopy tips with different magnetic anisotropy
Authors: Li Hongjia , Wei Dan , Piramanayagam S. N.
Published: February 2012

In magnetic force microscopy (MFM), it is effective to control the magnetic properties of the coating materials on the MFM tip to achieve higher resolution. In this work, the effect of the magnetic anisotropy of the tip-coating, such as perpendicular magnetic anisotropy (PMA), in-plane magnetic anisotropy (IMA), and random magnetic anisotropy (RMA), on the MFM image resolution are studied by micromagnetics. An accurate 3 D micromagnetic model of the CoPt pyramid MFM tip, with a cone angle of 37°, tip height of 120 nm, coating thickness of 7.6 nm, and average grain size of about 8.8 nm, was setup to calculate the domain structure and the stray field of the tip. A CoPt disk medium, with a bit size of 24 × 32 nm2 and film thickness of 8 nm, was chosen for image simulation. The PMA tip is advantageous in low scan height (SH) measurement with little tip-sample interaction due to its sharp and small stray field, while the IMA tip will disturb the magnetic moments of the medium at a low SH due to its strong stray field, and the RMA tip cannot read the bits with clear image contrast due to its broader field distribution.
Strain relaxation in Bi0.9Pb0.1FeO3/SrRuO3/SrTiO3 heterostructures
Authors: Bohra Murtaza , Wu C. P. , Yeh H. J. , Chou H.
Published: February 2012

The magnetic and crystalline properties of Bi0.9Pb0.1FeO3/SrRuO3(100 nm)/SrTiO3 heterostructures with different thickness of Bi0.9Pb0.1FeO3 (80–400 nm) are studied. The heterostructure undergoes a strain relaxation at each interface. Surprisingly, the crystal lattice of the bottom SrRuO3 layer can be manipulated by the top Bi0.9Pb0.1FeO3 layer, with its unit cell volume shrinking for a thicker top Bi0.9Pb0.1FeO3 layer. The magnetic properties of the bottom SrRuO3 layer seem independent of the change of its crystal structure. These extraordinary phenomena can be ascribed to the inter-diffusion of Bi and Pb ions of the top Bi0.9Pb0.1FeO3 layer into the bottom SrRuO3 layer and substrate.
Transport measurements on lateral MgB2/Fe/MgB2 junctions
Authors: Fabretti Savio , Schäfers Markus , Schebaum Oliver , Thomas Patrick , Thomas Andy
Published: February 2012

The magnetic anisotropy and transport properties of superconducting MgB2 thin films on MgO (100) substrates were studied. The films were prepared by rf/dc-magnetron cosputtering and with in situ annealing temperatures of 650 °C. The film orientation was measured by X-ray diffractometry, which revealed a c-axis orientation of the MgB2 films. The critical onset temperature without field cooling is 15.5 K. We found a critical field of 14.73 T parallel to the film plane and 10.79 T perpendicular to the film plane from transport measurements of the dependence of the applied magnetic field. Differential conductance measurements of a lateral MgB2/Fe/MgB2 junction show the Δπ gap and the Δσ gap.
Towards a better comprehension of plasma formation and heating in high performances electron cyclotron resonance ion sources (invited)
Authors: Mascali D. , Gammino S. , Celona L. , Ciavola G.
Published: February 2012

Further improvements of electron cyclotron resonance ion sources (ECRIS) output currents and average charge state require a deep understanding of electron and ion dynamics in the plasma. This paper will discuss the most recent advances about modeling of non-classical evidences like the sensitivity of electron energy distribution function to the magnetic field detuning, the influence of plasma turbulences on electron heating and ion confinement, the coupling between electron and ion dynamics. All these issues have in common the non-homogeneous distribution of the plasma inside the source: the abrupt density drop at the resonance layer regulates the heating regimes (from collective to turbulent), the beam formation mechanism and emittance. Possible means to boost the performances of future ECRIS will be proposed. In particular, the use of Bernstein waves, in preliminary experiments performed at Laboratori Nazionali del Sud (LNS) on MDIS (microwave discharge ion sources)-type sources, has permitted to sustain largely overdense plasmas enhancing the warm electron temperature, which will make possible in principle the construction of sources for high intensity multicharged ions beams with simplified magnetic structures.
Status of the SPIRAL I upgrade at GANIL
Authors: Jardin P. , Bajeat O. , Couratin C. , Delahaye P. , Dubois M. , Feierstein C. , Pellemoine F. , Lecomte P. , Lehérissier P. , Maunoury L. , Saint-Laurent M. G. , Traykov E.
Published: February 2012

The upgrade of the “Système de Production d’Ions Radioactifs en Ligne” phase I (SPIRAL I) installed at the “Grand Accélérateur National d’Ions Lourds” (GANIL) situated at Caen, France, is in progress and should be ready by 2014. In parallel, the first part of SPIRAL II facility is currently under construction. The global status of the upgrade is presented: goal, radioactive ion production systems, modification of the production cave and impact of the current safety re-evaluation of GANIL.
Multigan®: First experimental results
Authors: Maunoury L. , Pacquet J. Y. , Baret P. , Donzel X. , Dubois M. , Gaubert G. , Lehérissier P. , Leroy R. , Michel M. , Villarit A. C. C.
Published: February 2012

A new design of a multicharged ion source based on the MONO1000 ECRIS has been presented at the last ECR ion source (ECRIS) Workshop 2010. [L. Maunoury et al., in Proceedings of the XIXth International Workshop on ECR Ion Sources, Grenoble, France, 23–26 August 2010] This source has not only two opening at both ends but also a large space in the middle of the source enabling a direct contact with the ECR plasma. The source has been assembled mechanically and put on a test bench at the Pantechnik company. The primary tests have shown that the plasma ignition occurred at low pressure (10−6 mbar) and low RF power (10 W). The first experimental results (〈Q〉 = 1.30 for Ar and 1.85 for Xe) demonstrated the potential of this ion source in production of multicharged ion beams.
A particle-in-cell Monte Carlo code for electron beam ion source simulation
Authors: Zhao L. , Cluggish B. , Kim J. S. , Evstatiev E. G.
Published: February 2012

FAR-TECH, Inc., has developed a particle-in-cell Monte Carlo code (EBIS-PIC) to model ion motions in an electron beam ion source (EBIS). First, a steady state electron beam is simulated by the PBGUNS code (see http://far-tech.com/pbguns/index.html). Then, the injected primary ions and the ions from the background neutral gas are tracked in the trapping region using Monte Carlo method. Atomic collisions and Coulomb collisions are included in the EBIS-PIC model. The space charge potential is updated by solving the Poisson equation each time step. The preliminary simulation results are presented and compared with BNL electron beam test stand (EBTS) fast trapping experiments.
The Jahn-Teller effect in ${\rm CH}_{\rm 3} {\rm Cl}^{\rm + } ( {{\rm \tilde X}{}^{\rm 2}{\rm E}} )$ CH 3 Cl +(X̃E2): A combined high-resolution experimental measurement and ab initio theoretical study
Authors: Shao Zhuo , Li Hua , Zhang Shiyang , Li Juan , Dai Zuyang , Mo Yuxiang , Bae Yong Jin , Kim Myung Soo
Published: February 2012

The energy levels of ${\rm CH}_{\rm 3} {\rm Cl}^{\rm + } \left( {{\rm \tilde X}{}^{\rm 2}{\rm E}} \right)$ CH 3 Cl +X̃E2 showing strong spin-vibronic coupling effect (Jahn-Teller effect) have been measured up to 3500 cm−1 above the ground vibrational state using one-photon zero-kinetic energy photoelectron and mass-analyzed threshold ionization spectroscopic method. Theoretical calculations have been also performed to calculate the spin-vibronic energy levels using a diabatic model and ab initio adiabatic potential energy surfaces (PESs). In the theoretical calculations the diabatic potential energy surfaces are expanded by the Taylor expansions up to the fourth-order including the multimode vibronic interactions. The calculated spin-orbit energy splitting (224.6 cm−1) for the ground vibrational state is in good agreement with the experimental data (219 ± 3 cm−1), which indicates that the Jahn-Teller and the spin-orbit coupling have been properly described in the theoretical model near the zero-point energy level. Based on the assignments predicted by the theoretical calculations, the experimentally measured energy levels were fitted to those from the diabatic model by optimizing the main spectroscopic parameters. The PESs from the ab initio calculations at the level of CASPT2/vq(t)z were thus compared with those calculated from the experimentally determined spectroscopic parameters. The theoretical diagonal elements in the diabatic potential matrix are in good agreement with those determined using the experimental data, however, the theoretical off-diagonal elements appreciably deviate from those determined using the experimental data for geometric points far away from the conical intersections. It is also concluded that the JT effect in CH3Cl+ mainly arises from the linear coupling and the mode coupling between the CH3 deform (υ5) and CH3 rock (υ6) vibrations. The mode couplings between the symmetric C-Cl stretching vibration υ3 with υ5 and υ6 are also important to understand the spin-vibronic structure of the molecule.
A fresh look at dense hydrogen under pressure. II. Chemical and physical models aiding our understanding of evolving H–H separations
Authors: Labet Vanessa , Hoffmann Roald , Ashcroft N. W.
Published: February 2012

In order to explain the intricate dance of intramolecular (intra-proton-pair) H–H separations observed in a numerical laboratory of calculationally preferred static hydrogen structures under pressure, we examine two effects through discrete molecular models. The first effect, we call it physical, is of simple confinement. We review a salient model already in the literature, that of LeSar and Herschbach, of a hydrogen molecule in a spheroidal cavity. As a complement, we also study a hydrogen molecule confined along a line between two helium atoms. As the size of the cavity/confining distance decreases (a surrogate for increasing pressure), in both models the equilibrium proton separation decreases and the force constant of the stretching vibration increases. The second effect, which is an orbital or chemical factor, emerges from the electronic structure of the known molecular transition metal complexes of dihydrogen. In these the H–H bond is significantly elongated (and the vibron much decreased in frequency) as a result of depopulation of the σg bonding molecular orbital of H2, and population of the antibonding σu* MO. The general phenomenon, long known in chemistry, is analyzed through a specific molecular model of three hydrogen molecules interacting in a ring, a motif found in some candidate structures for dense hydrogen.
Temperature-modulated fluorescence tomography in a turbid media
Authors: Lin Yuting , Bolisay Linden , Ghijsen Michael , Kwong Tiffany C. , Gulsen Gultekin
Published: February 2012

High scattering in biological tissues makes fluorescence tomography inverse problem very challenging in thick medium. We describe an approach termed “temperature-modulated fluorescence tomography” that can acquire fluorescence images at focused ultrasound resolution. By utilizing recently emerged temperature sensitive fluorescence contrast agents, this technique provides fluorescence images with high resolution prior to any reconstruction process. We demonstrate that this technique is well suited to resolve small fluorescence targets located several centimeters deep in tissue.
Polymer translocation in solid-state nanopores: Dependence of scaling behavior on pore dimensions and applied voltage
Authors: Edmonds Christopher M. , Hudiono Yeny C. , Ahmadi Amir G. , Hesketh Peter J. , Nair Sankar
Published: February 2012

We investigate unforced and forced translocation of a Rouse polymer (in the absence of hydrodynamic interactions) through a silicon nitride nanopore by three-dimensional Langevin dynamics simulations, as a function of pore dimensions and applied voltage. Our nanopore model consists of an atomistically detailed nanopore constructed using the crystal structure of β-Si3N4. We also use realistic parameters in our simulation models rather than traditional dimensionless quantities. When the polymer length is much larger than the pore length, we find the translocation time versus chain length scales as τ ∼ N2+ν for the unforced case and as τ ∼ N(1+2ν)/(1+ν) for the forced case. Our results agree with theoretical predictions which indicate that memory effects and tension on the polymer chain play an important role during the translocation process. We also find that the scaling exponents are highly dependent on the applied voltage (force). When the length of the polymer is on the order of the length of the pore, we do not find a continuous scaling law, but rather scaling exponents that increase as the length of the polymer increases. Finally, we investigate the scaling behavior of translocation time versus applied voltage for different polymer and pore lengths. For long pores, we obtain the theoretical scaling law of τ ∼ 1/Vα, where α ≅ 1 for all voltages and polymer lengths. For short pores, we find that α decreases for very large voltages and/or small polymer lengths, indicating that the value of α = 1 is not universal. The results of our simulations are discussed in the context of experimental measurements made under different conditions and with differing pore geometries.
Unzipping and binding of small interfering RNA with single walled carbon nanotube: A platform for small interfering RNA delivery
Authors: Santosh Mogurampelly , Panigrahi Swati , Bhattacharyya Dhananjay , Sood A. K. , Maiti Prabal K.
Published: February 2012

In an effort to design efficient platform for siRNA delivery, we combine all atom classical and quantum simulations to study the binding of small interfering RNA (siRNA) by pristine single wall carbon nanotube (SWCNT). Our results show that siRNA strongly binds to SWCNT surface via unzipping its base-pairs and the propensity of unzipping increases with the increase in the diameter of the SWCNTs. The unzipping and subsequent wrapping events are initiated and driven by van der Waals interactions between the aromatic rings of siRNA nucleobases and the SWCNT surface. However, molecular dynamics (MD) simulations of double strand DNA (dsDNA) of the same sequence show that the dsDNA undergoes much less unzipping and wrapping on the SWCNT in the simulation time scale of 70 ns. This interesting difference is due to smaller interaction energy of thymidine of dsDNA with the SWCNT compared to that of uridine of siRNA, as calculated by dispersion corrected density functional theory (DFT) methods. After the optimal binding of siRNA to SWCNT, the complex is very stable which serves as one of the major mechanisms of siRNA delivery for biomedical applications. Since siRNA has to undergo unwinding process with the effect of RNA-induced silencing complex, our proposed delivery mechanism by SWCNT possesses potential advantages in achieving RNA interference.
Excitation of dust density waves in weak electric fields
Authors: Yaroshenko V. V. , Khrapak S. A. , Thomas H. M. , Morfill G. E.
Published: February 2012

Influence of the weak electric fields of the order of a few V/cm, inevitably existing in plasma discharges, on propagation of dust density waves is theoretically investigated for typical experimental conditions. The model predicts significant modifications of the dispersion of the dust acoustic modes due to equilibrium ion and dust flows and an existence of cut-off wavenumbers, corresponding to aperiodically growing dust density perturbations. The theory explains the preferential range of wavenumbers, where the dust density waves can be effective excited. Examples of dispersion curves are calculated for realistic complex plasma parameters and comparison with recent experiments is presented.
Relativistic spherical plasma waves
Authors: Bulanov S. S. , Maksimchuk A. , Schroeder C. B. , Zhidkov A. G. , Esarey E. , Leemans W. P.
Published: February 2012

Tightly focused laser pulses that diverge or converge in underdense plasma can generate wake waves, having local structures that are spherical waves. Here we study theoretically and numerically relativistic spherical wake waves and their properties, including wave breaking.
Correlations in liquid water for the TIP3P-Ewald, TIP4P-2005, TIP5P-Ewald, and SWM4-NDP models
Authors: Huggins David J.
Published: February 2012

Water is one of the simplest molecules in existence, but also one of the most important in biological and engineered systems. However, understanding the structure and dynamics of liquid water remains a major scientific challenge. Molecular dynamics simulations of liquid water were performed using the water models TIP3P-Ewald, TIP4P-2005, TIP5P-Ewald, and SWM4-NDP to calculate the radial distribution functions (RDFs), the relative angular distributions, and the excess enthalpies, entropies, and free energies. In addition, lower-order approximations to the entropy were considered, identifying the fourth-order approximation as an excellent estimate of the full entropy. The second-order and third-order approximations are ∼20% larger and smaller than the true entropy, respectively. All four models perform very well in predicting the radial distribution functions, with the TIP5P-Ewald model providing the best match to the experimental data. The models also perform well in predicting the excess entropy, enthalpy, and free energy of liquid water. The TIP4P-2005 and SWM4-NDP models are more accurate than the TIP3P-Ewald and TIP5P-Ewald models in this respect. However, the relative angular distribution functions of the four water models reveal notable differences. The TIP5P-Ewald model demonstrates an increased preference for water molecules to act both as tetrahedral hydrogen bond donors and acceptors, whereas the SWM4-NDP model demonstrates an increased preference for water molecules to act as planar hydrogen bond acceptors. These differences are not uncovered by analysis of the RDFs or the commonly employed tetrahedral order parameter. However, they are expected to be very important when considering water molecules around solutes and are thus a key consideration in modelling solvent entropy.
Stability of a nonlinear magnetic field diffusion wave
Authors: Oreshkin V. I. , Chaikovsky S. A.
Published: February 2012

The thermal instabilities that develop in a conductor during nonlinear diffusion of a magnetic field were treated in a linear approximation by solving an eigenvalue/eigenfunction problem and an initial value problem. The limiting increment of thermal instabilities has been determined for the principal mode (for the wave number tending to infinity) as γm∼∂δ∂T(jmax)2, where ∂δ∂T is the temperature derivative of resistivity and jmax is the maximum current density. It has been shown that as a nonlinear diffusion wave propagates through a conductor, the long-wave modes whose wavelengths are of the order of the conductor thickness are stable and the short-wave modes are localized near the diffusion wave front. As the diffusion wave arrives at the inner surface of the conductor, the instability increments of all modes with any wave number reach maxima.
Self-pulsing operating mode of hollow cathode discharge in noble gas
Authors: He Shoujie , Ouyang Jiting , He Feng , Jia Hui
Published: February 2012

The self-pulsing phenomenon of hollow cathode discharge in a semi-cylindrical hollow cathode in noble gas is investigated in this paper. The current-voltage (I-V) characteristics and the time evolution of the current and voltage of self-pulsing are measured under different conditions. The results show that the pulse frequency ranges from a few to tens kilohertz depending on the pressure and the averaged current. It increases with the averaged current and decreases as the pressure rising. The external parallel capacitances have no influence on the self-pulsing frequency. It is supposed that the mode transition between pre-discharge and hollow cathode discharge may contribute to the self-pulse.
Nonlinear ion-acoustic solitary waves in electronegative plasmas with electrons featuring Tsallis distribution
Authors: El Taibany W. F. , Tribeche Mouloud
Published: February 2012

Weakly nonlinear ion-acoustic (IA) solitary waves, which accompany electronegative plasmas composed of positive ions, negative ions, and nonextensive electrons are investigated. Allowing for electrons departure from Boltzmann’s distribution is shown to bear considerable new features of the IA soliton characteristics. Three different types of electronegative plasmas inspired from the experimental studies of Ichiki et al. [Phys. Plasmas 8, 4275 (2001)] are discussed, and the dependence of IA solitons basic characteristics on physical parameters is also investigated. It is found that for certain values of the negative-to-positive ion density ratio, ν, the positive-to-negative ion mass ratio, Q, and the nonextensive parameter, q, the plasma system supports rarefactive solitons.
High quality factor two dimensional GaN photonic crystal cavity membranes grown on silicon substrate
Authors: Vico Triviño N. , Rossbach G. , Dharanipathy U. , Levrat J. , Castiglia A. , Carlin J.-F. , Atlasov K. A. , Butté R. , Houdré R. , Grandjean N.
Published: February 2012

We report on the achievement of freestanding GaN photonic crystal L7 nanocavities with embedded InGaN/GaN quantum wells grown by metal organic vapor phase epitaxy on Si (111). GaN was patterned by e-beam lithography, using a SiO2 layer as a hard mask, and usual dry etching techniques. The membrane was released by underetching the Si (111) substrate. Micro-photoluminescence measurements performed at low temperature exhibit a quality factor as high as 5200 at ∼420 nm, a value suitable to expand cavity quantum electrodynamics to the near UV and the visible range and to develop nanophotonic platforms for biofluorescence spectroscopy.
State-to-state reaction probabilities within the quantum transition state framework
Authors: Welsch Ralph , Huarte-Larrañaga Fermín , Manthe Uwe
Published: February 2012

Rigorous quantum dynamics calculations of reaction rates and initial state-selected reaction probabilities of polyatomic reactions can be efficiently performed within the quantum transition state concept employing flux correlation functions and wave packet propagation utilizing the multi-configurational time-dependent Hartree approach. Here, analytical formulas and a numerical scheme extending this approach to the calculation of state-to-state reaction probabilities are presented. The formulas derived facilitate the use of three different dividing surfaces: two dividing surfaces located in the product and reactant asymptotic region facilitate full state resolution while a third dividing surface placed in the transition state region can be used to define an additional flux operator. The eigenstates of the corresponding thermal flux operator then correspond to vibrational states of the activated complex. Transforming these states to reactant and product coordinates and propagating them into the respective asymptotic region, the full scattering matrix can be obtained. To illustrate the new approach, test calculations study the D + H2(ν, j) → HD(ν′, j′) + H reaction for J = 0.
Aqueous solutions of divalent chlorides: Ions hydration shell and water structure
Authors: Bruni F. , Imberti S. , Mancinelli R. , Ricci M. A.
Published: February 2012

By combining neutron diffraction and Monte Carlo simulations, we have determined the microscopic structure of the hydration ions shell in aqueous solutions of MgCl2 and CaCl2, along with the radial distribution functions of the solvent. In particular the hydration shell of the cations, show cation specific symmetry, due to the strong and directional interaction of ions and water oxygens. The ions and their hydration shells likely form molecular moieties and bring clear signatures in the water-water radial distribution functions. Apart from these signatures, the influence of divalent salts on the microscopic structure of water is similar to that of previously investigated monovalent solutes, and it is visible as a shift of the second peak of the oxygen-oxygen radial distribution function, caused by distortion of the hydrogen bond network of water.