bluuebunny/crossref_metadata_2025 huggingface dataset:
Selection of silicon wafer for power devices and the influence of crystal defects including impurities
Authors: Yamamoto Hidekazu , Hashizume Tamotsu
Published: January 2011

Silicon wafers used as starting materials are significantly different in MOS‐LSIs and power devices, because each device requires a specific structure. For power devices, FZ wafers or epitaxial wafers with a thick epitaxial layer are widely used. Epitaxial wafers are advantageous with respect to low breakdown voltage devices, and FZ wafers are advantageous for high breakdown voltage devices. The influence of COPs formed during CZ crystal growth on highly miniaturized MOS‐LSIs is significant; however, COPs do not pose a problem to power devices prepared from FZ or epitaxial wafers. BMDs and slip dislocations have caused device failures on power devices where the device operation layer is deep and the process temperature is high. On the other hand, misfit dislocations which are generated with high concentration do not introduce device failures. Failure due to physical contamination is observed when Fe has introduced a failure to the power device. Cu/pit failures occur due to chemical contamination by Cu only for more highly miniaturized MOS‐LSIs, but are not a problem for power devices whose miniaturization level is not required as that for MOS‐LSIs. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microstructural tuning of polycrystalline silicon films from hydrogen diluted amorphous silicon films by AIC
Authors: Prathap P. , Tuzun O. , Roques S. , Schmitt S. , Maurice C. , Slaoui A.
Published: January 2011

In the present study, the effect of hydrogen dilution in amorphous silicon on its crystallization kinetics and defect distribution using AIC has been studied. The a ‐Si films were deposited at different ratios of H2/(H2+SiH4) using plasma enhanced chemical vapour deposition (ECR‐PECVD) on glass‐ceramic substrates. The thicknesses of aluminium and a ‐Si:H films were 0.20 μm and 0. 37 μm, respectively. The bi‐layer structures were annealed in a tube furnace at 475 °C for 8 hours in a nitrogen atmosphere. The results indicated that as the hydrogen dilution for a ‐Si:H films increased from 0% to 85%, the AIC grown poly‐Si films were more stressed compressively, while the Raman peak broadened from 6.7 cm‐1 to 8.6 cm‐1. It was found that the initiation of crystallization temperature as well as microstructure of poly‐Si films was dramatically influenced by the hydrogen content in precursor a ‐Si films. The distribution of microstructural defects analysed by Electron Back Scattering Diffraction (EBSD) method indicated that frequency of low angle grain boundaries (LAGB) were more at higher hydrogen dilution ratios while coincident site lattice boundaries (CSL) of first order (Σ3), second order (Σ9) and third order (Σ27) were less sensitive to the hydrogen dilutions/content (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Decoration and preferential etching of crystal defects in silicon materials: influence of metal decoration on the defect etching process
Authors: Idrisi H. , Sinke T. , Gerhardt V. , Ceglarek D. , Kolbesen B. O.
Published: January 2011

Delineation of crystal defects in SOI wafers can be accomplished by preferential etching with solutions such as dilute Secco etch. By application of decoration procedures with metals such as copper or lithium delineation of defects by preferential etching can be improved due to acceleration of the etching process at the metal decorated defects. Parameters such as removal rate, selectivity and activation energy for the etching process are used to describe the influence of metal decoration on preferential etching of defects in SOI wafers. In this work the selectivity of a dilute Secco etch was determined experimentally on dislocations generated by damaging silicon substrates by indentation with a diamond tip and subsequent annealing at 1000 °C. After dilute Secco etching the depth of the dislocation etch pits was measured by an atomic force microscope. Both the selectivity and the activation energy were compared for non‐decorated and copper or lithium decorated samples of SOI wafers or silicon substrates. Typical values obtained for activation energies of non‐decorated samples were 29‐33 kJ/mol, those of decorated samples were in the range of 25‐34 kJ/mol. For the selectivity the values for non‐decorated samples were about 1.95 and increased with the level of copper decoration up to 3.0. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Negative ion yield and sputter yield variations for Cs+ bombardment of Si with O2 gas flooding
Authors: Franzreb Klaus , Williams Peter
Published: January 2011

We have investigated whether negative secondary ion yields from Cs+ sputtered silicon might be improved by simultaneous O2 gas flooding, which lowers the sputter yield of the silicon, and thus, might increase the cesium content at the surface. The composition at the sputtered surface is derived from quantitative measurements of the ratios of O/Si and Cs/Si in the total emitted flux using the recently developed oxygen 18 method1 and sputter yield measurements, respectively (with XSi + XCs + XO = 1). The silicon sputter yield, Y, is lowered by adsorbed oxygen by as much as a factor of 2.7 and is found to scale almost linearly with the silicon atom fraction XSi at the surface, resulting in the cesium atom fraction XCs at the surface remaining nearly constant during oxygen flooding. We find that oxidation of the cesiated silicon surface influences differently the useful ion yields (ions detected/atom sputtered) of various elements. The yields of B− and Cs− are enhanced by factors of 3 and 34, respectively, the yield of O− remains roughly constant, and yields of other elements (As−, Cl−, P−, Sb−, Si−) are lowered by a factor of 2 or 3. Copyright © 2010 John Wiley & Sons, Ltd.
The development of SIMS and international SIMS conferences: a personal retrospective view
Authors: Benninghoven A.
Published: January 2011

Today SIMS is a well‐established and widely applied surface analytical technique, featuring the many unique properties of mass spectrometry. It is successfully applied to virtually all kinds of solid materials, for bulk and thin layer as well as for surface analysis. The fast development of SIMS started in the late 1950s and continues until today. It has been characterized by a number of key developments, which include the control of ion yields by the application of selected atomic and molecular or cluster ions, the development of high‐performance instrumentation by the development of special operation modes, and several attempts to understand and predict the secondary ion formation processes. Starting in 1977, these developments have been accompanied by and mirrored in the series of international SIMS conferences. The development of the technique as well as the conference series and their strong interaction is described in a pronounced personal retrospective view. Copyright © 2011 John Wiley & Sons, Ltd.
A perspective on voluntary and involuntary outreach services for the homeless mentally ill
Authors: Tsemberis Sam , Elfenbein Cherie
Published: January 2011

Outreach teams use a range of strategies to engage people who are homeless and mentally ill and living on the streets. This chapter describes and evaluates the effectiveness of various voluntary and involuntary approaches and presents a new model program for serving this population.
Domestic violence in the psychiatric emergency service
Authors: Barthauer Linda
Published: January 2011

Domestic violence is a frequent precipitant to PES presentation. This chapter discusses case recognition, screening tools, and the debate surrounding mandatory reporting requirements.
Psychiatric emergency services in the veterans health administration: A review
Authors: Noronha Stephen F. , Desai Prakash N.
Published: January 2011

The VA health care system is the largest source of public mental health care in the country, providing specialty mental health care services to more than 550,000 veterans annually. This chapter reviews the nature and scope of VA psychiatric emergency services.
Trends in the incidence and prevalence of Alzheimer's disease, dementia, and cognitive impairment in the United States
Authors: Rocca Walter A. , Petersen Ronald C. , Knopman David S. , Hebert Liesi E. , Evans Denis A. , Hall Kathleen S. , Gao Sujuan , Unverzagt Frederick W. , Langa Kenneth M. , Larson Eric B. , White Lon R.
Published: January 2011

Declines in heart disease and stroke mortality rates are conventionally attributed to reductions in cigarette smoking, recognition and treatment of hypertension and diabetes, effective medications to improve serum lipid levels and to reduce clot formation, and general lifestyle improvements. Recent evidence implicates these and other cerebrovascular factors in the development of a substantial proportion of dementia cases. Analyses were undertaken to determine whether corresponding declines in age‐specific prevalence and incidence rates for dementia and cognitive impairment have occurred in recent years. Data spanning 1 or 2 decades were examined from community‐based epidemiological studies in Minnesota, Illinois, and Indiana, and from the Health and Retirement Study, which is a national survey. Although some decline was observed in the Minnesota cohort, no statistically significant trends were apparent in the community studies. A significant reduction in cognitive impairment measured by neuropsychological testing was identified in the national survey. Cautious optimism appears justified.
Counting dementia: There is no one “best” way
Authors: Launer Lenore J.
Published: January 2011

The growing societal and individual burden of dementia means that counting the cases of dementia is critical. There are several approaches and methods that can be used to identify dementia cases. The ascertainment can range from very detailed characterization of the individual (deep) to a brief standardized assessment (wide) that emphasizes individual functioning. The choice of going deep or wide depends on the goal of the ascertainment. These goals are discussed, as well as the emerging issues that may change the way dementia cases are classified.
Bodies Real and Virtual: Joseph Rock and Enrico Caruso in the Sino-Tibetan Borderlands
Authors: Mueggler Erik
Published: January 2011

In 1934, during twenty-eight years of wandering west China, the American botanist Joseph Francis Charles Rock made a brief trip to England. He clipped the obituary of an old friend from the Times and pasted it in his diary. On the facing page, he pasted a photograph two decades old, and wrote this caption:

J. F. Rock (standing) with his older friend Fred Muir, Entomologist at the Haw[aii] Sugar Planter's Exp[eriment] Sta[tion], Honolulu. Photographed in our home in Liloa Rise (Breaside), Honolulu in the spring of 1913, while our phonograph played Spiritu Gentile, Caruso singing.
The Jealous Institution: Male Nubility, Conjugality, Sexuality, and Discipline on the Social Margins of Imperial Brazil
Authors: Beattie Peter M.
Published: January 2011

In 1997, an “attempted rebellion” erupted in the Professor Barreto Campelo Penitentiary on Itamaracá Island, Pernambuco. A journalist reported that the suspension of conjugal visits sparked a brawl in which three inmates were stabbed before guards restored order. The warden clarified that conjugal visits had been suspended after fights broke out between rival cellblocks when someone pilfered objects visitors had brought to prisoners. A woman who desired anonymity informed, “The convicts notified us in the afternoon by way of notes that they would fight again that night. I think that the lack of contact with their female companions leaves all of the men agitated.” The warden brokered a truce with the inmates' leaders in part by promising that conjugal visits would resume the next week. The reporter concluded, almost as an afterthought, that inmates renewed protests about the overcrowding of eleven hundred inmates into a jail designed for four hundred.
Family obligations and support behaviour: a United States–Netherlands comparison
Authors: COONEY TERESA M. , DYKSTRA PEARL A.
Published: January 2011

This study draws on national survey data from the United States of America (USA) and the Netherlands to compare family obligations and support behaviour for middle-generation adults who have a living aged parent and adult child. Consistent with afamilialism by default hypothesisbased on welfare state differences, the US sample espouses stronger family obligations than the Dutch sample. Yet, the Dutch respondents are more likely to engage in family support behaviours with both the younger and older generations, contrary to afamily-steps-in hypothesis. The connection between family obligations and support behaviour is also tested, revealing a stronger association in the US sample, consistent with afamily-steps-in hypothesis, but only in regard to relations with ageing parents. We conclude that Dutch respondents are more likely to act on their individual preferences whereas American respondents are more influenced by general norms of obligation towards family members. The findings are discussed in terms of social policy differences between the two countries, and in light of results from comparative European studies of intergenerational relations.
Towards a Critical Theory of Democratic Peace
Authors: HOBSON CHRISTOPHER
Published: January 2011

The Democratic Peace research programme remains a prominent and influential strand of International Relations theory. It occupies a central place in the discipline, both as a dominant version of liberal internationalism, and as a supposedly paradigmatic case demonstrating the strengths of positivist scholarship. Nonetheless, Democratic Peace scholarship has been challenged by recent real world events, notably the belligerent behaviour of democratic states during the so-called ‘War on Terror’, and the use of its findings to justify the US led invasion of Iraq. In this regard, Democratic Peace research has struggled to deal with the ethical and practical consequences of its work, as the focus has been on empirically observable and testable problems that fit within the remit of positivist social scientific practice. Responding to this state of affairs, it is argued here that there is a pressing need to further extend and pluralise existing scholarship by incorporating approaches which commence from different ontological, epistemological and methodological starting points. While there are multiple possibilities, Frankfurt School Critical Theory has great potential to contribute to an expanded research agenda. The article outlines what a Critical Theory approach to the study of Democratic Peace would entail, highlighting the substantial contribution it can make.
Microbiological and epidemiological investigation of the Neisseria meningitidis serogroup A epidemic in Niger in 2009: last wave before the introduction of the serogroup A meningococcal conjugate vaccine?
Authors: COLLARD J. M. , MAMAN Z. , ABANI A. , MAINASARA H. B. , DJIBO S. , YACOUBA H. , MAITOURNAM R. , SIDIKOU F. , NICOLAS P. , ROCOURT J. , JUSOT J. F.
Published: January 2011

The 2009 meningitis season in Niger was characterized by an early onset, beginning in the very first weeks of the year and peaking from the 12th to the 15th week with 5655 clinical cases over the 4 weeks. From 1 January 2009 to 28 June 2009 (week 26), a total of 13 733 clinical cases of meningitis were reported to the national epidemiological surveillance system with a case-fatality rate of 4·2%. During the season 25 of the 42 health districts reached the epidemic threshold and 11 the alert threshold. Reactive mass vaccination campaigns involving a total of 5 166 741 doses of the polysaccharide meningococcal bivalent (A+C) vaccine progressively controlled the outbreak in most parts of the country. A total of 3755 cerebrospinal fluid samples representing 28·1% of the suspected meningitis cases were analysed. Serogroup A meningococci were the causative agent in 97·5% of the meningococcal cases. Multi-locus sequence typing of 26 meningococal serogroup A strains showed 25 sequence type (ST)7 and one ST2859, both sequence types belonging to the ST5 clonal complex (CC5) of subgroup III. This is the largest epidemic observed in Niger since those of 1995–1996 (59 948 notified cases) and 2000 (14 633 notified cases).
Increased influenza-related healthcare utilization by residents of an urban aboriginal community
Authors: CHARLAND K. M. , BROWNSTEIN J. S. , VERMA A. , BREWER T. , JONES S. , HOEN A. GATEWOOD , BUCKERIDGE D. L.
Published: January 2011

Most studies describing high rates of acute respiratory illness in aboriginals have focused on rural or remote communities. Hypothesized causes include socioeconomic deprivation, limited access to healthcare, and a high prevalence of chronic disease. To assess influenza rates in an aboriginal community while accounting for healthcare access, deprivation and chronic disease prevalence, we compared rates of influenza-related outpatient and emergency-department visits in an urban Mohawk reserve (Kahnawá:ke) to rates in neighbouring regions with comparable living conditions and then restricted the analysis to a sub-population with a low chronic disease prevalence, i.e. those aged <20 years. Using medical billing claims from 1996 to 2006 we estimated age-sex standardized rate ratios. The rate in Kahnawá:ke was 58% greater than neighbouring regions and 98% greater in the analysis of those aged <20 years. Despite relatively favourable socioeconomic conditions and healthcare access, rates of influenza-related visits in Kahnawá:ke were elevated, particularly in the younger age groups.
Measuring antibody levels in bulk-tank milk as an epidemiological tool to search for the status ofCoxiella burnetiiin dairy sheep
Authors: RUIZ-FONS F. , ASTOBIZA I. , BARANDIKA J. F. , JUSTE R. A. , HURTADO A. , GARCÍA-PÉREZ A. L.
Published: January 2011

Pooling samples may provide a valuable alternative to individual testing for pathogen surveillance purposes. We studied the reliability of measuring the level of antibodies againstCoxiella burnetiiin bulk-tank milk (BTM) to estimate the seroprevalence ofC. burnetiiin dairy sheep in 34 flocks. We then estimated the seroprevalence ofC. burnetiiin 154 dairy sheep flocks according to the level of antibodies in BTM. We tested for the accuracy of our estimation at the population level by comparing predicted meanC. burnetiiflock seroprevalence with that obtained in another survey performed on the same population. Our findings showed that testing BTM by ELISA is a cost-effective and relatively good index of the seroprevalence ofC. burnetiiin dairy sheep and may be a useful tool for epidemiological surveillance at the population level.
Waterborne norovirus outbreak in a municipal drinking-water supply in Sweden
Authors: RIERA-MONTES M. , BRUS SJÖLANDER K. , ALLESTAM G. , HALLIN E. , HEDLUND K.-O. , LÖFDAHL M.
Published: January 2011

During Easter 2009, almost 200 people resident in a small Swedish village fell ill with gastrointestinal symptoms. We conducted a retrospective cohort study and a molecular investigation in order to identify the source of the outbreak. Residents living in households connected to the public water network were at an increased risk of developing disease (relative risk 4·80, 95% confidence interval 1·68–13·73) compared to those with no connection to the public network. Norovirus genotype GI.3 was identified in stool samples from six patients and in a sample from the public water network. Contamination of one of the wells supplying the public water network was thought to be the source of the outbreak. This is a description of a norovirus outbreak linked to a municipal drinking-water supply in Sweden. Information from epidemiological and molecular investigations is of utmost importance to guide outbreak control measures and to prevent future outbreaks.
Nader Shah and Persian Naval Expansion in the Persian Gulf, 1700–1747
Authors: AXWORTHY MICHAEL
Published: January 2011

The purpose of this article is to relate a remarkable episode involving Nader Shah's navy and to connect it directly to the wider aims and projects of his regime (notably his ambitions in India), and the central events of his reign. In this way his Persian Gulf policy may emerge not as the oddity it might at first appear, but rather as a consistent element in a coherent larger whole.
Advising the State: Bureaucratic Leadership and the Crisis of Governance in Pakistan, 1952–2000
Authors: NIAZ ILHAN
Published: January 2011

This article examines four important turning points (1952, 1961, 1982 and 2000) in Pakistan's history. In each case, the government of the day, faced with serious challenges, solicited/received advice from the bureaucratic leadership. In each case, the latter placed before the former options that, though often different from conventional wisdom or popular prescriptions, offered real hope of a long-term solution to some of Pakistan's problems. And on each occasion, this advice was rejected or ignored by the politicians, arguably at great cost to the country and to its rulers. This article employs a historian's hindsight and argues that at key points in Pakistan's history the bureaucratic leadership did what it was supposed to – provide sound advice based on empirical appreciation of Pakistan's predicament and the enlightened self-interest of the government. Today, it is widely perceived that Pakistan's senior civil servants do not even bother to advise the politicians in power. Indeed, Pakistan's crisis of state cannot be overcome unless the esprit de corps and professional integrity of the civil service are rebuilt. The consequences of failure on this front are so greatly negative for the entire region that focused and sustained efforts are needed to rehabilitate Pakistan's bureaucratic leadership.
Two new subfamilies of DNA mismatch repair proteins (MutS) specifically abundant in the marine environment
Authors: Ogata Hiroyuki , Ray Jessica , Toyoda Kensuke , Sandaa Ruth-Anne , Nagasaki Keizo , Bratbak Gunnar , Claverie Jean-Michel
Published: January 2011

MutS proteins are ubiquitous in cellular organisms and have important roles in DNA mismatch repair or recombination. In the virus world, the amoeba-infecting Mimivirus, as well as the recently sequenced Cafeteria roenbergensis virus are known to encode a MutS related to the homologs found in octocorals and ɛ-proteobacteria. To explore the presence of MutS proteins in other viral genomes, we performed a genomic survey of four giant viruses (‘giruses’) (Pyramimonas orientalis virus (PoV), Phaeocystis pouchetii virus (PpV), Chrysochromulina ericina virus (CeV) and Heterocapsa circularisquama DNA virus (HcDNAV)) that infect unicellular marine algae. Our analysis revealed the presence of a close homolog of Mimivirus MutS in all the analyzed giruses. These viral homologs possess a specific domain structure, including a C-terminal HNH-endonuclease domain, defining the new MutS7 subfamily. We confirmed the presence of conserved mismatch recognition residues in all members of the MutS7 subfamily, suggesting their role in DNA mismatch repair rather than DNA recombination. PoV and PpV were found to contain an additional type of MutS, which we propose to call MutS8. The MutS8 proteins in PoV and PpV were found to be closely related to homologs from ‘Candidatus Amoebophilus asiaticus’, an obligate intracellular amoeba-symbiont belonging to the Bacteroidetes. Furthermore, our analysis revealed that MutS7 and MutS8 are abundant in marine microbial metagenomes and that a vast majority of these environmental sequences are likely of girus origin. Giruses thus seem to represent a major source of the underexplored diversity of the MutS family in the microbial world.
CO2 and vitamin B12 interactions determine bioactive trace metal requirements of a subarctic Pacific diatom
Authors: King Andrew L , Sañudo-Wilhelmy Sergio A , Leblanc Karine , Hutchins David A , Fu Feixue
Published: January 2011

Phytoplankton growth can be limited by numerous inorganic nutrients and organic growth factors. Using the subarctic diatom Attheya sp. in culture studies, we examined how the availability of vitamin B12 and carbon dioxide partial pressure (pCO2) influences growth rate, primary productivity, cellular iron (Fe), cobalt (Co), zinc (Zn) and cadmium (Cd) quotas, and the net use efficiencies (NUEs) of these bioactive trace metals (mol C fixed per mol cellular trace metal per day). Under B12-replete conditions, cells grown at high pCO2 had lower Fe, Zn and Cd quotas, and used those trace metals more efficiently in comparison with cells grown at low pCO2. At high pCO2, B12-limited cells had ∼50% lower specific growth and carbon fixation rates, and used Fe ∼15-fold less efficiently, and Zn and Cd ∼3-fold less efficiently, in comparison with B12-replete cells. The observed higher Fe, Zn and Cd NUE under high pCO2/B12-replete conditions are consistent with predicted downregulation of carbon-concentrating mechanisms. Co quotas of B12-replete cells were ∼5- to 14-fold higher in comparison with B12-limited cells, suggesting that >80% of cellular Co of B12-limited cells was likely from B12. Our results demonstrate that CO2 and vitamin B12 interactively influence growth, carbon fixation, trace metal requirements and trace metal NUE of this diatom. This suggests the need to consider complex feedback interactions between multiple environmental factors for this biogeochemically critical group of phytoplankton in the last glacial maximum as well as the current and future changing ocean.
Analysis of N-Glycosylation Sites in HIV glycoprotein 160
Authors: Mandage Rajendra
Published: January 2011

HIV infection is a condition caused by the human immunodeficiency virus. The condition gradually destroys the immune system, which makes it harder for the body to fight infections. HIV presents a complex knot for scientists to unravel. An envelope protein of the human HIV that is encoded by the env gene contains numerous glycosylation sites. It serves as a precursor for both the GP120 and the GP41. Here statistical investigation was done to study the sequential aspects of amino acids around the N-glycosylated protein from HIV virus. Sequences containing N-glycosylated asparagine were selected from the uniprot database of N-glycosylated proteins. The frequency of occurrence of amino acid residues around the glycosylated asparagine showed that there are increased numbers of isoleucine and threonine residues around the N-glycosylation sites in comparison with the nonglycosylated asparagine residues. Preferential occurrence of amino acid residues around the glycosylation site shows that T has the maximum preference around the N-glycosylation site. T at 3 and/or -3 positions strongly favors glycosylation irrespective of other glycosylation sites. The data presented in the present work clearly indicate that there is a pronounced positional preference for the hydrophobic and neutral amino acids at various positions around the N-glycosylation site. In the future it will be of much interest to investigate further the possible structural and conformational implications of some of these suggested positional preferences of the various amino acids around the site of glycosylation. This is a potentially important study, and such analyses will surely contribute an important part of our knowledge base in the future on HIV research. These results will be of interest to molecular biologists and protein engineers to identify N-glycosylation sites important in molecular recognition processes in HIV virus.
Phase transition in a log-normal Markov functional model
Authors: Pirjol Dan
Published: January 2011

We derive the exact solution of a one-dimensional Markov functional model with log normally distributed interest rates and constant volatility in discrete time. The model is shown to have two distinct limiting states, corresponding to small and asymptotically large volatilities, respectively. These volatility regimes are separated by a phase transition at some critical value of the volatility, at which certain expectation values display nonanalytical behavior as a function of volatility. We investigate the conditions under which this phase transition occurs and show that it is related to the position of the zeros of an appropriately defined generating function in the complex plane, in analogy with the Lee–Yang theory of the phase transitions in condensed matter physics.
Quasiparticle current in ballistic F/ScN junctions
Authors: Kulagina I. V. , Krivoruchko V. N.
Published: January 2011

The current-voltage (I-V) characteristics of ballistic F/ScN junctions, consisting of a hybrid F/S bilayer of ferromagnetic (F) and superconducting (S) metals and a normal (N) metal, are studied. It is assumed that the size of the constriction, c, is much smaller than the electron mean free path and the superconducting coherence length, and that the transparency is rather high. The amplitudes of Andreev and normal reflection of electrons with specified spin orientations from the constriction are calculated. It is shown that the exchange field (hex) induced in the S metal causes spin splitting of the features of the differential conductivity of the junction. Measurements of the spin splitting of the junction conductivity, which is proportional to hex, can be used to study the induced magnetism of superconductors in hybrid S/F structures with the aid of the measured I-V characteristics of F/ScN junctions.
Vortex resistivity owing to the magnetic field of the transport current in wide superconducting films
Authors: Zolochevskii I. V.
Published: January 2011

The resistive properties of vortex superconducting films are studied experimentally over a wide temperature range. It is shown that in superconducting films whose width w is an order of magnitude greater than the penetration depth λ⊥(T) of the magnetic field (w∕λ⊥(T)>10), the differential resistance of the linear vortex part of the current-voltage characteristic is independent of temperature, in accordance with the Aslamazov-Lempitskii model for the vortex resistive state. Immediately adjacent to Tc, in the region where the effective sizes of the vortices and antivortices which produce the film current resistance in chains exceed half the width of the film, i.e., 4<w∕λ⊥(T)<8, a sharp increase in the differential resistance of the vortex segment of the current-voltage characteristic is observed as T→Tc that is not explained by existing theories.
Structure and magnetic properties of multi-walled carbon nanotubes modified with iron
Authors: Grechnev G. E. , Desnenko V. A. , Fedorchenko A. V. , Panfilov A. S. , Kolesnichenko Yu. A. , Matzui L. Yu. , Grybova M. I. , Prylutskyy Yu. I. , Ritter U. , Scharff P.
Published: January 2011

Magnetic properties of multi-walled carbon nanotubes modified with iron (MWCNT+Fe) are studied in detail in the temperature range 4.2–300K. Carbon encapsulated Fe nanoparticles were produced by chemical vapor deposition. Low-temperature SQUID magnetization measurements are supplemented by structural studies employing thermogravimetric (TG) analysis, transmission electron microscopy (TEM), x-ray diffraction spectroscopy (XRD), and scanning electron microscopy (SEM). The magnetic susceptibility of MWCNT+Fe was also studied above room temperature to provide a complete picture of its magnetic phase transitions.
Kinetics of He4 gas sorption by fullerite C60. Quantum effects
Authors: Dolbin A. V. , Esel’son V. B. , Gavrilko V. G. , Manzhelii V. G. , Vinnikov N. A. , Popov S. N.
Published: January 2011

The kinetics of helium gas sorption by C60 powder and subsequent desorption of the He4 impurity from the saturated powder is studied in the temperature interval 2–292K. Evidence is obtained supporting the existence of two stages in the temperature dependences of sorption and desorption. These stages originate in different times taken by helium to occupy octahedral and tetrahedral interstices in the C60 lattice. The characteristic times of sorption and desorption coincide. It is found that the temperature dependences of the characteristic times for occupying the octahedral and tetrahedral interstices are nonmonotonic. When the temperature is lowered from 292to79.3K, the characteristic times increase, which indicates thermally activated diffusion of helium in C60. With a further reduction to T=10K, the characteristic times decrease by more than an order of magnitude. Below 8K the characteristic times of sorption and desorption are temperature-independent. This suggests tunnel diffusion of He4 in C60.
Effect of deformation and heat treatment with equal-channel, multiple-angle pressing on the superconducting properties of NbTi alloy
Authors: Beloshenko V. A. , Chishko V. V. , Matrosov N. I. , Dyakonov V. P. , Szymczak R. , Piętoza J. , Puźniak R. , Szymczak H. , Gajda D. , Zaleski A.
Published: January 2011

The effect of equal-channel, multiple-angle pressing combined with hydroextrusion and drawing, on the critical current density, pinning force, and superconducting transition temperature of bimetallic Nb+60at.% Ti wires is examined.
Superconductivity of 80NbN–20SiO2 granular films
Authors: Yuzephovich O. I. , Bengus S. V. , Kościelska B. , Witkowska A.
Published: January 2011

The feasibility of creating granular superconducting films of NbN–SiO2 with a controlled grain size by a sol-gel method is demonstrated. A comprehensive study is made of the structural and transport properties of granular films of 80%NbN–20%SiO2 with different thicknesses. It is found that production of a complete superconducting transition requires that the samples have thicknesses greater than 750nm. The critical temperatures for a superconducting transition and the upper critical magnetic fields are roughly constant for films with different thicknesses and equal 4.5K and 4.4T, respectively. A crossover from 2D to 3D behavior is discovered in the temperature variation of the upper parallel critical field. It is shown that at low magnetic fields the resistive transitions obey an Arrhenius law. The mechanism for broadening of resistive transitions in magnetic fields is most likely magnetic flux creep. The magnetic field dependence of the activation energy is obtained. Typical initial signs of a magnetically induced superconductor-insulator transition are observed at high magnetic fields.
Magnetic order-order phase transitions in magnets with collective electrons: MnCoSi
Authors: Valkov V. I. , Golovchan A. V. , Dvornikov E. A. , Todris B. M.
Published: January 2011

First principles calculations of the electronic structure of MnCoSi and a spiral state model are used to analyze magnetic-field induced magnetic order-order phase transitions in MnCoSi at pressures up to 2kbar. This shows that the magnetic moments of Mn and Co in MnCoSi are created by collective d-electrons and that pressure stimulation of induced order-order transitions in this material can be a consequence of structural changes in the density of d-electron states as the pressure is raised. Induced order-order transitions are described by a single-band model for the spiral state in which the band filling and the nonmagnetic density of electron states are based on first principles calculations of the electronic structure of MnCoSi. This model shows that the low-temperature states induced by a magnetic field are not collinear ferromagnetic structures, but may represent the coexistence of a homogeneous ferromagnetic component and a periodic spiral component of the total magnetic moment of the d-band. A pure ferromagnetic state at low temperatures can be regarded as metastable.
Spin polarization oscillations in a magnetically inhomogeneous conducting ring
Authors: Pyshkin P. V.
Published: January 2011

The real part of the conductance of a 1D conducting ring with magnetic properties that vary along the conductor is examined. The possibility of exciting a new type of spin polarization oscillations in the ring with an external emf is analyzed.
Multi-year comparisons of fish recruitment, growth and production in two drought-affected Iberian estuaries
Authors: Dolbeth Marina , Martinho Filipe , Freitas Vânia , Costa-Dias Sérgia , Campos Joana , Pardal Miguel Ângelo
Published: January 2011

Climate extremes, such as drought and floods, are increasing and should be considered in ecosystem management plans. The effects of an extreme drought were studied in two estuaries of the Iberian coast, Minho and Mondego, by exploring fish recruitment, growth and production over four years. The two estuaries are located within an area with transitional climate, and differ considerably in size, availability of freshwater wetlands and freshwater inflow. Fishes from the Minho estuary, at higher latitude, generally had lower growth rates and later timing of recruitment. During the drought, freshwater inflow was severely reduced in both estuaries. The overall fish assemblage production in the Minho estuary decreased considerably, whereas in the Mondego estuary it showed an increase. However, the drought effects seemed highly species‐specific and dependent on local geomorphology; the increase in the Mondego estuary was a result of an increase in a single species, whereas other species decreased or maintained similar production levels. Decreases in production in both estuaries were attributed to direct and indirect effects of changes in the freshwater inflow during the study period. This parameter should therefore be considered when undertaking management plans for transitional waters.
Migration of green turtles (Chelonia mydas) from Australasian feeding grounds inferred from genetic analyses
Authors: Dethmers Kiki E. M. , Jensen Michael P. , FitzSimmons Nancy N. , Broderick Damien , Limpus Colin J. , Moritz Craig
Published: January 2011

Coastal seagrass habitats in tropical and subtropical regions support aggregations of resident green turtles (Chelonia mydas) from several genetically distinct breeding populations. Migration of individuals to their respective dispersed breeding sites provides a complex pattern of migratory connectivity among nesting and feeding habitats of this species. An understanding of this pattern is important in regions where the persistence of populations is under threat from anthropogenic impacts. The present study uses mitochondrial DNA and mixed-stock analyses to assess the connectivity among seven feeding grounds across the north Australian coast and adjacent areas and 17 genetically distinct breeding populations from the Indo-Pacific region. It was hypothesised that large and geographically proximate breeding populations would dominate at nearby feeding grounds. As expected, each sampled feeding area appears to support multiple breeding populations, with two aggregations dominated by a local breeding population. Geographic distance between breeding and feeding habitat strongly influenced whether a breeding population contributed to a feeding ground (wi = 0.654); however, neither distance nor size of a breeding population was a good predictor of the extent of their contribution. The differential proportional contributions suggest the impact of anthropogenic mortality at feeding grounds should be assessed on a case-by-case basis.
Multiple sources of nutrients add to the complexities of predicting marine benthic community responses to enrichment
Authors: O'Brien Allyson L. , Morris Liz , Keough Michael J.
Published: January 2011

Understanding biological responses to nutrient enrichment under different environmental conditions is integral for the effective management of eutrophication in coastal environments. However, current conceptual models of nutrient enrichment are limited as they are based on studies that only consider a single source of nutrients, when in reality it is more likely that enrichment is a result of multiple sources. Here, we test the hypothesis that biological responses to nutrient enrichment in intertidal mudflat assemblages depend on the source by comparing enrichment from a controlled release fertilizer with that from decomposing macroalgae. Sediment at two sites in Port Phillip Bay, Victoria, were dosed with the different nutrient sources and monitored through time. After six weeks, the macroalgae-enriched plots had significantly higher abundances and biomass of some taxa of deposit-feeding polychaetes. In the fertilizer-enriched plots, the porewater nutrients increased but there was no detectable change in abundances or biomass of infauna, suggesting that the nutrients did not assimilate into the foodweb. The rate of assimilation of anthropogenic nutrients potentially occurs over longer time scales compared with the rapid assimilation and biological responses to decomposing macroalgae. Responses to the different nutrient sources provide new insights into the complexity of nutrient enrichment models that are applied to the management of aquatic ecosystems worldwide.
Action potentials drive body wall muscle contractions in
Caenorhabditis elegans
Authors: Gao Shangbang , Zhen Mei
Published: January 2011

The sinusoidal locomotion exhibited by
Caenorhabditis elegans
predicts a tight regulation of contractions and relaxations of its body wall muscles. Vertebrate skeletal muscle contractions are driven by voltage-gated sodium channel–dependent action potentials. How coordinated motor outputs are regulated in
C. elegans
, which does not have voltage-gated sodium channels, remains unknown. Here, we show that
C. elegans
body wall muscles fire all-or-none, calcium-dependent action potentials that are driven by the L-type voltage-gated calcium and Kv1 voltage-dependent potassium channels. We further demonstrate that the excitatory and inhibitory motoneuron activities regulate the frequency of action potentials to coordinate muscle contraction and relaxation, respectively. This study provides direct evidence for the dual-modulatory model of the
C. elegans
motor circuit; moreover, it reveals a mode of motor control in which muscle cells integrate graded inputs of the nervous system and respond with all-or-none electrical signals.
The Temporal Dynamics of Effect Anticipation in Course of Action Planning
Authors: Ziessler Michael , Nattkemper Dieter
Published: January 2011

“Strong” versions of the ideomotor theory of action control claim that anticipations of the environmental effects that actions bring about are mandatory for response selection. This is considered to be the one and only way of how actions can be voluntarily selected. We studied this notion in a series of four experiments where we adapted the flanker paradigm to investigate the involvement of effect codes in the preparation of motor responses. Participants first learned that their responses to stimulus letters were contingently followed by the presentation of a new letter on the screen. In the second phase of the experiments, the action-demanding letters were presented together with the effects of the correct response, effects of other responses, or neutral letters. Varying the stimulus onset asynchrony (SOA) between target stimuli and the flanking effect stimuli provides the opportunity to investigate the temporal dynamics of the activation of effect codes. Hence, flanker stimuli were presented before, simultaneously with, or after the onset of the target. The results indicate that effect-related information from the flanker stimuli is involved in the preparation process, but mainly in later phases of response preparation. The observed pattern of results suggests that, at least under conditions where responses are determined by stimuli, effect codes are activated in course of response planning to enable the evaluation of the executed response and the monitoring of response execution, but they do not automatically activate the responses themselves.
Centrality of the congruence kernel for elementary subgroups of Chevalley groups of rank >1 over noetherian rings
Authors: Rapinchuk Andrei , Rapinchuk Igor
Published: January 2011

Let

G
G

be a universal Chevalley-Demazure group scheme associated to a reduced irreducible root system of rank

>
1.

>1.

For a commutative ring

R
R

, we let

Γ
=
E
(
R
)

\Gamma = E(R)

denote the elementary subgroup of the group of

R
R

-points

G
(
R
)
.

G(R).

The congruence kernel

C
(
Γ
)

C(\Gamma )

is then defined to be the kernel of the natural homomorphism

Γ
^

→

Γ
¯

,

\widehat {\Gamma } \to \overline {\Gamma },

where

Γ
^

\widehat {\Gamma }

is the profinite completion of

Γ
\Gamma

and

Γ
¯

\overline {\Gamma }

is the congruence completion defined by ideals of finite index. The purpose of this paper is to show that for an arbitrary noetherian ring

R
R

(with some minor restrictions if

G
G

is of type

C
n

C_n

or

G
2

G_2

), the congruence kernel

C
(
Γ
)

C(\Gamma )

is central in

Γ
^

.

\widehat {\Gamma }.
Semi-terminal continua in Kelley spaces
Authors: Prajs Janusz
Published: January 2011

A continuum

K
K

in a space

X
X

is said to be semi-terminal if at least one out of every two disjoint continua in

X
X

intersecting

K
K

is contained in

K
K

. Based on this concept, new structural results on Kelley continua are obtained. In particular, two decomposition theorems for Kelley continua are presented. One of these theorems is an improved version of the aposyndetic decomposition theorem for Kelley continua.
A novel mitochondrial outer membrane protein, MOMA-1, that affects cristae morphology inCaenorhabditis elegans
Authors: Head Brian P. , Zulaika Miren , Ryazantsev Sergey , van der Bliek Alexander M.
Published: January 2011

Three proteins with similar effects on mitochondrial morphology were identified in an RNA interference (RNAi) screen for mitochondrial abnormalities in Caenorhabditis elegans. One of these is the novel mitochondrial outer membrane protein MOMA-1. The second is the CHCHD3 homologue, CHCH-3, a small intermembrane space protein that may act as a chaperone. The third is a mitofilin homologue, IMMT-1. Mitofilins are inner membrane proteins that control the shapes of cristae. RNAi or mutations in each of these genes change the relatively constant diameters of mitochondria into highly variable diameters, ranging from thin tubes to localized swellings. Neither growth nor brood size of the moma-1, chch-3, or immt-1 single mutants is affected, suggesting that their metabolic functions are normal. However, growth of moma-1 or immt-1 mutants on chch-3(RNAi) leads to withered gonads, a lack of mitochondrial staining, and a dramatic reduction in fecundity, while moma-1; immt-1 double mutants are indistinguishable from single mutants. Mutations in moma-1 and immt-1 also have similar effects on cristae morphology. We conclude that MOMA-1 and IMMT-1 act in the same pathway. It is likely that the observed effects on mitochondrial diameter are an indirect effect of disrupting cristae morphology.
Efficient simulation under a population genetics model of carcinogenesis
Authors: Zhu Tianqi , Hu Yucheng , Ma Zhi-Ming , Zhang De-Xing , Li Tiejun , Yang Ziheng
Published: January 2011

Motivation: Cancer is well known to be the end result of somatic mutations that disrupt normal cell division. The number of such mutations that have to be accumulated in a cell before cancer develops depends on the type of cancer. The waiting time Tm until the appearance of m mutations in a cell is thus an important quantity in population genetics models of carcinogenesis. Such models are often difficult to analyze theoretically because of the complex interactions of mutation, drift and selection. They are also computationally expensive to simulate because of the large number of cells and the low mutation rate.

Results: We develop an efficient algorithm for simulating the waiting time Tm until m mutations under a population genetics model of cancer development. We use an exact algorithm to simulate evolution of small cell populations and coarse-grained τ-leaping approximation to handle large populations. We compared our hybrid simulation algorithm with the exact algorithm in small populations and with available asymptotic results for large populations. The comparison suggested that our algorithm is accurate and computationally efficient. We used the algorithm to study the waiting time for up to 20 mutations under a Moran model with variable population sizes. Our new algorithm may be useful for studying realistic models of carcinogenesis, which incorporates variable mutation rates and fitness effects.

Contact:  z.yang@ucl.ac.uk