bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the caudate artery with three‐dimensional imaging
Authors: Oshiro Yukio , Sasaki Ryoko , Takeguchi Takaya , Ibukuro Kenji , Ohkohchi Nobuhiro
Published: March 2013

Background/purpose

To date there have been only a few radiological studies of the caudate artery. This study aimed to precisely analyze the caudate artery as well as the relationship between the caudate arteries, the arterial plexus at the hilar plate, and the hilar bile duct.

Methods

Reconstructed three‐dimensional (3D) computed tomography images from 50 patients during hepatic arteriography were analyzed. The caudate arteries were classified as right branches (Irs) or left branches (Ils). The communicating artery (CA) was defined as the artery connecting the right, left, segmental, and common hepatic arteries.

Results

The caudate artery was divided into 3 types: an independent branch (Type 1); the common tract formed by Ir and Il (Type 2); and an arterial branch from the CA (Type 3). The CA was recognized in 25 of 50 patients. There was a total of 65 arteries to the hilar bile duct observed in 40 patients, and 24 (37 %) of these 65 arteries to the hilar bile duct originated from the caudate artery or CA.

Conclusion

The caudate artery plays an important role not only in connecting the blood supply of the right and left livers but in the blood supply to the hilar bile duct.
Regionalisierungsprozesse von wissensintensiven Dienstleistungsaktivitäten: Veränderung des Stadt-Umland-Verhältnisses im deutschen Städtesystem
Authors: Growe Anna
Published: March 2013

This paper examines the emergence of a new urban-rural relationship on the basis of the development of nodes of knowledge-intensive services in the German urban system. It will be discussed whether the relocation of knowledge-based services into regional hinterlands in the German urban system leads to a changed city-hinterland relation. It will be analysed if networks are affected by processes of regionalisation and concentrated deconcentration can be observed in the German urban system. To understand the influence of regionalisation processes on cities as hubs, developments will be observed from two different perspectives (embeddedness and network integration) that mirror two facets of cities as hubs.
Morphine‐enhanced apoptosis in selective brain regions of neonatal rats
Authors: Bajic Dusica , Commons Kathryn G. , Soriano Sulpicio G.
Published: March 2013

Prolonged neonatal opioid exposure has been associated with: antinociceptive tolerance, long‐term neurodevelopmental delay, cognitive, and motor impairment. Morphine has also been shown to induce apoptotic cell death in vitro studies, but its in vivo effect in developing rat brain is unknown. Thus, we hypothesized that prolongued morphine administration in neonatal rats in a model of antinociceptive tolerance and dependence is associated with increased neuroapoptosis. We analyzed neonatal rats from the following groups (1) naïve group (n = 6); (2) control group (normal saline (NS), n = 5), and (3) morphine group (n = 8). Morphine sulfate or equal volume of NS was injected subcutaneously twice daily for 6½ days starting on postnatal day (PD) 1. Development of antinociceptive tolerance was previously confirmed by Hot Plate test on the 7th day. Evidence of neuronal and glial apoptosis was determined by cleaved caspase‐3 immunofluorescence combined with specific markers. At PD7, morphine administration after 6½ days significantly increased the density of apoptotic cells in the cortex and amygdala, but not in the hippocampus, hypothalamus, or periaqueductal gray. Apoptotic cells exhibited morphology analogous to neurons. Irrespective of the treatment, only a very few individual microglia but not astrocytes were caspase‐3 positive. In summary, repeated morphine administration in neonatal rats (PD1–7) is associated with increased supraspinal apoptosis in distinct anatomical regions known to be important for sensory (cortex) and emotional memory processing (amygdala). Brain regions important for learning (hippocampus), and autonomic and nociceptive processing (hypothalamus and periaqueductal gray) were not affected. Lack of widespread glial apoptosis or robust glial activation following repeated morphine administration suggests that glia might not be affected by chronic morphine at this early age. Future studies should investigate long‐term behavioral sequelae of demonstrated enhanced apoptosis associated with prolonged morphine administration in a neonatal rat model.
Joint ergodicity of actions of an abelian group
Authors: SON YOUNGHWAN
Published: March 2013

Let $G$ be a countable abelian group and let ${T}^{(1)} , {T}^{(2)} , \ldots , {T}^{(s)} $ be measure preserving $G$-actions on a probability space. We prove that joint ergodicity of ${T}^{(1)} , {T}^{(2)} , \ldots , {T}^{(s)} $ implies total joint ergodicity if each ${T}^{(i)} $ is totally ergodic. We also show that if $G= { \mathbb{Z} }^{d} $, $s\geq d+ 1$ and the actions ${T}^{(1)} , {T}^{(2)} , \ldots , {T}^{(s)} $ commute, then total joint ergodicity of ${T}^{(1)} , {T}^{(2)} , \ldots , {T}^{(s)} $ follows from joint ergodicity. This can be seen as a generalization of Berend’s result for commuting $ \mathbb{Z} $-actions.
Some consequences of the shadowing property in low dimensions
Authors: KOROPECKI ANDRES , PUJALS ENRIQUE R.
Published: March 2013

We consider low-dimensional systems with the shadowing property and we study the problem of existence of periodic orbits. In dimension two, we show that the shadowing property for a homeomorphism implies the existence of periodic orbits in every $\epsilon $-transitive class, and in contrast we provide an example of a ${C}^{\infty } $ Kupka–Smale diffeomorphism with the shadowing property exhibiting an aperiodic transitive class. Finally, we consider the case of transitive endomorphisms of the circle, and we prove that the $\alpha $-Hölder shadowing property with $\alpha \gt 1/ 2$ implies that the system is conjugate to an expanding map.
USES AND “AUTOMATIC” RESULTING TRUSTS OF FREEHOLD
Authors: Jones N.G.
Published: March 2013

Drawing upon the history of the doctrine of the old use, Professor John Mee has suggested both that the extent of the authority for a “retention” approach to “automatic” resulting trusts has been overlooked, and that while as a matter of history a “retention” approach has significant support, as a matter of principle in the modern law it is not fully satisfactory, so that it is necessary to look elsewhere for a theoretical explanation for the “automatic” resulting trust. This article examines the reasons for the inconsistency identified by Professor Mee, seeking to elucidate the relationship between uses and trusts, to contribute to the history of resulting uses and trusts, and to explain why the modern “automatic” resulting trust has become a rule in search of a rationale.
IT'S ONLY WORDS: ON MEANING AND MENS REA
Authors: Stark Findlay
Published: March 2013

In English law, mens rea terms can be defined differently depending on the context. This article attacks this approach, arguing that it pays insufficient attention to the criminal law's twin needs to communicate effective guidance to citizens who wish to avoid punishment, and to control the discretion accorded to the criminal law's institutions. It would be preferable to have clear definitions of mens rea terms applied uniformly across the criminal law. If there are gaps, these ought to be filled by additional mens rea terms. The practical issues raised by this argument are considered briefly.
David Montgomery: A Biography
Authors: Montgomery Claude D.
Published: March 2013

David Montgomery, union organizer, political and civil rights activist, and well-known scholar of American labor history died suddenly on December 2, 2011. A retired Yale University Farnum Professor of History, he is equally well known for his publications and skill as a teacher as he was as an advocate for equality and for his tireless support for workers and trade unions. Through his published works and lectures—in English, Italian, Portuguese, and Spanish—Montgomery's influence as a historian of workers' history and their struggles for equality and survival was felt by workers, students, and academics in several countries.
Indian Labor History
Authors: Parthasarathi Prasannan
Published: March 2013

The 1980s and 1990s were decades of great creativity in Indian labor history. The study of labor moved from a long-standing institutional focus on trade unions to a study of workers themselves, as well as from the economism and determinism that had characterized many previous writings. A growing interest in labor led to the first conference devoted to Indian labor history at the International Institute of Social History in Amsterdam in 1995 and the founding of the Association of Indian Labour Historians the following year. The dynamism and the new intellectual horizons of Indian labor history in that period are captured in the work of three major historians: Dipesh Chakrabarty, Rajnarayan Chandavarkar, and Chitra Joshi. For the purposes of this essay, there is no need to review their contributions in detail (not least because such overviews may be found elsewhere), but it is nevertheless essential to provide a quick sketch of the arguments of each.
Montgomery the Mentor, Montgomery the Activist
Authors: Redmond Shana L.
Published: March 2013

I'd like to begin with a disclosure: I was not an official student of David Montgomery. By “official,” I mean to signal the parochial ways in which institutions recognize and quantify mentorship. I came to Yale University too late to have the opportunity to work with him in any formal way; I entered the combined doctoral program in African American studies and American studies there in the fall of 2002, long after David had retired. While this fact presented a major obstacle to those of my graduate colleagues who hoped to work with him, it was only a minor disadvantage for me because David and I were already connected through a genealogy of mentoring; my college mentor was Peter Rachleff, one of David's Pitt students, and he made sure that each of us knew of the other upon my arrival in New Haven. What I didn't know of David—and there was a lot—I would soon learn through my numerous engagements with him and his work.
From Warwick to Pittsburgh: Shaping the New Labor Historians
Authors: Kirk Neville
Published: March 2013

It was at Warwick that I first met David. I was an MA student in Comparative British and American Labour and Social History during the academic year 1968–1969. David's genuinely honest, open, and down-to-earth approach to his students and teaching and learning in general appealed to many like myself who had been raised in solid, respectable, independent, and self-respecting working-class households. He treated me fairly and squarely, without any hint of those patronizing and condescending attitudes, which sometimes characterize middle-class academics in their treatment of working-class students. Montgomery, like Edward Thompson, expected us to work hard and would have no truck with those self-indulgent students who regarded political activism as a valid substitute for academic study. True to his 1950s past, David kept regular “factory” hours. He strongly disapproved of lateness or absence in the submission of work and attendance at lectures and seminars. As “apprentices,” we, the MA postgraduates, were to be rigorously instructed in the rules and methods of the trade by Montgomery and the other “master craftsmen” at Warwick. As part of our training, we were subjected to full critical gaze of these masters when we presented our papers and research findings to them at three-hour combined postgraduate and staff seminars on Friday afternoons. Escape and a mixture of relief and reward were found immediately afterward in the student bar.
An Extraordinary Man, An Extraordinary Historian
Authors: Graziosi Andrea
Published: March 2013

David Montgomery was both an extraordinary man and an extraordinary historian. All one needs to do is look at his autobiographical interview, which appeared in Visions of History in 1983, to know this. I had the good fortune of studying and then collaborating with David from 1979 at the University of Pittsburgh until the late 1990s at Yale University. While he had been recruited to Yale in the wake of the academic and political success of his Workers' Control in America, in my view his most beautiful book remains his first, Beyond Equality. Told with passion, intelligence, and an impressive richness of detail, it is the remarkable story of American labor and the Left immediately after the Civil War. At that time, the Republican Party, led by a friend of Marx, pursued arguably the most progressive policies of any Western government in history, embodying that world of free labor and social and racial equality, which had emerged victorious from the war against slavery. David discovered and reconstructed this world, with its special blend of liberty and justice, after having spent ten years as a skilled worker and communist trade unionist in the factories of the 1950s. During that period, he shared his political commitment with his radiant wife, Marty, who was from a large African American communist family in Chicago. In fact, the two met on a ship that was carrying both of them to the World Youth Congress in Prague.
The Leading Labor Historian in the United States
Authors: Freeman Joshua B.
Published: March 2013

David Montgomery, the leading labor historian in the United States, died on December 2, 2011, at age eighty-four. His many articles and books, especially Beyond Equality: Labor and the Radical Republicans, 1862–1872; Workers' Control in America: Studies in the History of Work, Technology, and Labor Struggles; and The Fall of the House of Labor: The Workplace, the State, and American Labor Activism, 1865–1925, profoundly reshaped our understanding of the history of American workers.
Larger Than Life: Remembering David
Authors: Hanagan Michael
Published: March 2013

David Montgomery was larger than life in his personal style and self-presentation as well as in his spirit. Both watching and listening to him in conversation were a treat. So absorbed would he become in explaining some little-known incident of labor militancy that his entire body would get involved, his hand gestures and physical movements growing broader, requiring his listener to stand back to get a fuller view. His intense interest in labor history and patient willingness to share his knowledge with younger scholars testified to his faith in labor far more effectively than any manifesto. He communicated a sense of labor history as a shared enterprise in which we were all fellow workers.
David Montgomery in Brazil
Authors: Hall Michael M. , Batalha Cláudio
Published: March 2013

David Montgomery's semester as a Fulbright lecturer at the State University of Campinas, Brazil, in 1986 proved quite memorable. Bela Bianca, a member of the anthropology department who had known David and Marty when she was on a postdoctoral grant at Yale, made the initial contacts. A few specialists here had read Workers' Control in America at the time, but his work was not yet widely known in Brazil. However, questions about the labor process and control over production had become subjects of lively academic debate, largely on the basis of works by social scientists. The labor historians then being read were primarily French and British.
Rethinking the Underclass: Future Directions in Southern African Labor History
Authors: Callebert Ralph
Published: March 2013

Southern and South African labor history has, at least since the 1970s, been as much about the future of the region as about its past. Liberal scholars saw in apartheid and segregation irrational aberrations to the color-blind logic of capitalism. They believed the apartheid state to be an instrument of racial dominance but saw it as more or less neutral in terms of class relations. Economic growth and the abolishment of racial laws would bring freedom and equality—or at least equal opportunities. On the other hand, radical historians and sociologists thought of apartheid as a system that guaranteed the exploitation of cheap black labor for the benefit of capital. For them, apartheid was functional to capitalism.2While both the liberal and the radical positions were often more nuanced than the other side would admit, the question that divided these two camps was one about politics and strategy: Would capitalist development bring an end to racial domination, or was it part of the problem? In the latter case, challenging apartheid and colonialism would also involve challenging capitalism. The vibrancy of these debates should continue to serve as an inspiration for labor historians. I will argue that for the Left to be able to formulate viable alternatives to present policies, we should look at the history and nature of labor and inequality in the region.
Bringing Ideology Back In: Chinese Labor Studies in a Time of Transformation
Authors: Zhang Xiaodan
Published: March 2013

During the last thirty years, market reforms have turned China into an economic behemoth as the country moves deeper and deeper into capitalist development. The study of Chinese labor owes its dynamism in recent years to this dramatic economic and social transformation. Scholars are intrigued by two parallel historical transformations: On the one hand, millions of peasant migrants have been transformed into urban industrial and service workers; on the other hand, millions of former state-owned enterprise employees have lost their lifelong “iron rice bowl” job security and other benefits that they enjoyed under the Maoist socialist system. The new directions of labor studies about China reflect the unique trajectories of these important institutional and social changes. If earlier discussions mainly focused on the harsh labor conditions in sweatshops and despotic management in all kinds of factories, recent research and writing have explored a variety of emergent questions, from the impact of the new labor laws and institutional arrangements to the formation of a new working class and its relation to Chinese workers' recently highlighted legal rights and resistance. These studies have already contributed greatly to our knowledge of what is going on with Chinese workers and their labor movements in the twenty-first century.
Burden of illness and factors associated with duration of illness in clinical campylobacteriosis
Authors: DECKERT A. E. , REID-SMITH R. J. , TAMBLYN S. , MORRELL L. , SELISKE P. , JAMIESON F. B. , IRWIN R. , DEWEY C. E. , BOERLIN P. , McEWEN S. A.
Published: March 2013

A population-based study investigated the burden of illness, including the duration of illness associated with laboratory-confirmed cases of campylobacteriosis in two health unit areas. Questionnaire data were collected for 250 cases. The median duration of illness was 8 days and 66% of cases reported symptoms of moderate severity or greater. A Cox proportional hazards model identified antimicrobial use factors associated with a significantly increased rate of symptom resolution (shorter duration of illness): macrolides for less than the recommended number of days, ciprofloxacin for at least 3 days, and antimicrobials not recommended for campylobacteriosis. The impact of antimicrobial use was consistent regardless of when, during the course of illness, the antimicrobial use began. The effectiveness of ciprofloxacin in these results may be due to the low prevalence of resistance to ciprofloxacin in isolates from this study. The effect of antimicrobials not recommended for campylobacteriosis should be further investigated.
The brewery horse and the importance of equine power in Hanoverian London
Authors: ALMEROTH-WILLIAMS THOMAS
Published: March 2013

Hanoverian London was a city full of people, a city built by people for people. These impressions dominate traditional studies of the metropolis to a remarkable extent. By contrast, historians have largely overlooked the ubiquitous presence of non-human animals in the city and underestimate their impact on urban life. This article challenges key assumptions about the Hanoverian metropolis by highlighting the role of its quadruped architects, and specifically its working horses. In doing so, it urges the recognition of animals as influential actors in social, urban and economic history. The article focuses on the role of the horse in brewing, a major metropolitan industry which relied heavily on equine power. Crucially, it shows that the brewery horse became more, rather than less, influential during the industrial revolution.
Carbon Nanotube-Polymer Composites
Authors:   Royal Society of Chemistry,   Royal Society of Chemistry
Published: March 2013

Chemically-modified carbon nanotubes (CNTs) exhibit a wide range of physical and chemical properties which makes them an attractive starting material for the preparation of super-strong and highly-conductive fibres and films. Much information is available across the primary literature, making it difficult to obtain an overall picture of the state-of-the-art. This volume brings together some of the leading researchers in the field from across the globe to present the potential these materials have, not only in developing and characterising novel materials but also the devices which can be fabricated from them. Topics featured in the book include Raman characterisation, industrial polymer materials, actuators and sensors and polymer reinforcement, with chapters prepared by highly-cited authors from across the globe. A valuable handbook for any academic or industrial laboratory, this book will appeal to newcomers to the field and established researchers alike.
The release of trapped gases from amorphous solid water films. II. “Bottom-up” induced desorption pathways
Authors: Alan May R. , Scott Smith R. , Kay Bruce D.
Published: March 2013

In this (Paper II) and the preceding companion paper (Paper I; R. May, R. Smith, and B. Kay, J. Chem. Phys. 138, 104501 (2013)10.1063/1.4793311), we investigate the mechanisms for the release of trapped gases from underneath amorphous solid water (ASW) films. In Paper I, we focused on the low coverage regime where the release mechanism is controlled by crystallization-induced cracks formed in the ASW overlayer. In that regime, the results were largely independent of the particular gas underlayer. Here in Paper II, we focus on the high coverage regime where new desorption pathways become accessible prior to ASW crystallization. In contrast to the results for the low coverage regime (Paper I), the release mechanism is a function of the multilayer thickness and composition, displaying dramatically different behavior between Ar, Kr, Xe, CH4, N2, O2, and CO. Two primary desorption pathways are observed. The first occurs between 100 and 150 K and manifests itself as sharp, extremely narrow desorption peaks. Temperature programmed desorption is utilized to show that these abrupt desorption bursts are due to pressure induced structural failure of the ASW overlayer. The second pathway occurs at low temperature (typically <100 K) where broad desorption peaks are observed. Desorption through this pathway is attributed to diffusion through pores formed during ASW deposition. The extent of desorption and the line shape of the low temperature desorption peak are dependent on the substrate on which the gas underlayer is deposited. Angle dependent ballistic deposition of ASW is used to vary the porosity of the overlayer and strongly supports the hypothesis that the low temperature desorption pathway is due to porosity that is templated into the ASW overlayer by the underlayer during deposition.
Spectral distribution of excitation-dependent recombination rate in an In0.13Ga0.87N epilayer
Authors: Jarašiūnas K. , Nargelas S. , Aleksiejūnas R. , Miasojedovas S. , Vengris M. , Okur S. , Morkoç H. , Özgür Ü. , Giesen C. , Tuna Ö. , Heuken M.
Published: March 2013

Time-resolved optical techniques of photoluminescence (PL), light-induced transient grating (LITG), and differential transmission spectroscopy were used to investigate carrier dynamics in a single 50-nm thick In0.13Ga0.97N epilayer at high photoexcitation levels. Data in wide spectral, temporal, excitation, and temperature ranges revealed novel features in spectral distribution of recombination rates as follows: at low injection levels, an inverse correlation of carrier lifetime increasing with temperature and diffusivity decreasing with temperature confirmed a mechanism of diffusion-limited nonradiative recombination at extended defects. Carrier dynamics in the spectral region below the absorption edge but ∼70 meV above the PL band revealed a recombination rate that increased with excitation, while recombination rate in PL emission band (420–430 nm) decreased after saturation of trapping centers. Monitoring of spectrally integrated carrier dynamics by LITG technique allowed us to ascribe the enhanced recombination rate to bimolecular recombination and determine its coefficient B = 7 × 10−11 cm3/s. Complementary measurements unveiled the cause of PL efficiency saturation at injection levels above 5 × 1018 cm−3, attributable to bandgap renormalization in the extended states above the PL emission band, which encumbers carrier transfer from high-to-low energy states. As the degree of localization, and therefore, the total number of band tail states is expected to increase with In content, their impact to dependence of PL efficiency on excitation density could even be stronger for higher In compositions. These results provided insight that spectrally resolved carrier generation-recombination rates are excitation-dependent and would play a critical role in saturation of internal quantum efficiency in InGaN alloys used in light emitters, such as light emitting diodes.
Appraisal of molecular tailoring approach for large clusters
Authors: Sahu Nityananda , Yeole Sachin D. , Gadre Shridhar R.
Published: March 2013

High level ab initio investigations on molecular clusters are generally restricted to those of small size essentially due to the nonlinear scaling of corresponding computational cost. Molecular tailoring approach (MTA) is a fragmentation-based method, which offers an economical and efficient route for studying larger clusters. However, due to its approximate nature, the MTA-energies carry some errors vis-à-vis their full calculation counterparts. These errors in the MTA-energies are reduced by grafting the correction at a lower basis set (e.g., 6-31+G(d)) onto a higher basis set (e.g., aug-cc-pvdz or aug-cc-pvtz) calculation at MP2 level of theory. Further, better estimates of energies are obtained by making use of many-body interaction analysis. For this purpose, R-goodness (Rg) parameters for the three- and four-body interactions in a fragmentation scheme are proposed. The procedure employing grafting and many-body analysis has been tested out on molecular clusters of water, benzene, acetylene and carbon dioxide. It is found that for the fragmentation scheme having higher three- and four-body Rg-values, the errors in MTA-grafted energies are reduced typically to ∼0.2 mH at MP2 level calculation. Coupled with the advantage in terms of computational resources and CPU time, the present method opens a possibility of accurate treatment of large molecular clusters.
The symmetry groups of noncommutative quantum mechanics and coherent state quantization
Authors: Chowdhury S. Hasibul Hassan , Ali S. Twareque
Published: March 2013

We explore the group theoretical underpinning of noncommutative quantum mechanics for a system moving on the two-dimensional plane. We show that the pertinent groups for the system are the two-fold central extension of the Galilei group in (2+1)-space-time dimensions and the two-fold extension of the group of translations of \documentclass[12pt]{minimal}\begin{document}$\mathbb {R}^4$\end{document}R4. This latter group is just the standard Weyl-Heisenberg group of standard quantum mechanics with an additional central extension. We also look at a further extension of this group and discuss its significance to noncommutative quantum mechanics. We build unitary irreducible representations of these various groups and construct the associated families of coherent states. A coherent state quantization of the underlying phase space is then carried out, which is shown to lead to exactly the same commutation relations as usually postulated for this model of noncommutative quantum mechanics.
Core-shell structure disclosed in self-assembled Cu-Ag nanoalloy particles
Authors: Tchaplyguine M. , Andersson T. , Zhang Ch. , Björneholm O.
Published: March 2013

Core-shell segregation of copper and silver in self-assembled, free nanoparticles is established by means of photoelectron spectroscopy in a wide range of relative Cu-Ag concentrations. These conclusions are based on the analysis of the photon-energy-dependent changes of the Cu 3d and Ag 4d photoelectron spectra. The nanoparticles are formed from mixed Cu-Ag atomic vapor created by magnetron sputtering of a bimetallic sample in a gas-aggregation cluster source. Even at similar Cu and Ag fractions in the primary vapor the surface of the nanoparticles is dominated by silver. Only at low Ag concentration copper appears on the surface of nanoparticles. For the latter case, a threefold decrease in the Ag 4d spin-orbit splitting has been detected. The specific component distribution and electronic structure changes are discussed in connection with the earlier results on Cu-Ag macroscopic and surface alloys.
Compensation effects in GaN:Mg probed by Raman spectroscopy and photoluminescence measurements
Authors: Kirste Ronny , Hoffmann Marc P. , Tweedie James , Bryan Zachary , Callsen Gordon , Kure Thomas , Nenstiel Christian , Wagner Markus R. , Collazo Ramón , Hoffmann Axel , Sitar Zlatko
Published: March 2013

Compensation effects in metal organic chemical vapour deposition grown GaN doped with magnesium are investigated with Raman spectroscopy and photoluminescence measurements. Examining the strain sensitive E2(high) mode, an increasing compressive strain is revealed for samples with Mg-concentrations lower than 7 × 1018 cm−3. For higher Mg-concentrations, this strain is monotonically reduced. This relaxation is accompanied by a sudden decrease in crystal quality. Luminescence measurements reveal a well defined near band edge luminescence with free, donor bound, and acceptor bound excitons as well as a characteristic donor acceptor pair (DAP) luminescence. Following recent results, three acceptor bound excitons and donor acceptor pairs are identified. Along with the change of the strain, a strong modification in the luminescence of the dominating acceptor bound exciton and DAP luminescence is observed. The results from Raman spectroscopy and luminescence measurements are interpreted as fingerprints of compensation effects in GaN:Mg leading to the conclusion that compensation due to defect incorporation triggered by Mg-doping already affects the crystal properties at doping levels of around 7 × 1018 cm−3. Thereby, the generation of nitrogen vacancies is introduced as the driving force for the change of the strain state and the near band edge luminescence.
Band-engineered CaTiO3 nanowires for visible light photocatalysis
Authors: Fu Q. , Li J. L. , He T. , Yang G. W.
Published: March 2013

We have theoretically investigated the structural, electronic, and optical properties of the perovskite CaTiO3 nanowires for visible light photocatalytic applications using pseudopotential density-functional theory calculations. The electronic structure calculations show that the band gap is greatly modified in the CaTiO3 nanowires compared with that of the bulk. For the TiO2-terminated nanowires, the electronic states on the valence band maxima induced by combining oxygen and calcium atoms on the surface lead to a shift in the valence band toward the conduction band without interference from the edge of the conduction band, which reduces the band gap. On the contrary, the electronic states induced by combining oxygen and calcium atoms on the surface of the CaO-terminated nanowires lead to a shift in the conduction band toward the valence band. The calculated optical results indicate that the absorption edge of the nanowires shifts towards the red-light region. These theoretical results suggest that the perovskite CaTiO3 nanowires are promising candidates for visible light photocatalysis such as solar-assisted water splitting reactions.
Altering the exchange bias in Co90Fe10/(Co,Fe)O bilayers by changing the antiferromagnet's magnetism via interfacial ion-beam bombardment and different single crystalline MgO substrates
Authors: Shueh C. , Liu C.-H. , Skoropata E. , Wu T.-H. , van Lierop J. , Lin K.-W.
Published: March 2013

In this study, we investigated the exchange bias (coupling) effects in CoFe/(Co,Fe)O bilayers by using different single crystal substrates of MgO(100) and MgO(110) and Ar ion-beam bombardment on the surface of the bottom antiferromagnet (Co,Fe)O layer before capping with ferromagnet CoFe. In the CoFe/(Co,Fe)O/MgO(110) bilayer, above the irreversibility temperature (Tirr. ∼ 170 K), there was a rapid decrease in M(T) with increasing temperature, unlike the CoFe/(Co,Fe)O/MgO(100) film that showed an increased Tirr. ∼ 300 K and no observable decrease in M(T) above Tirr. The different M vs T zero-field-cooled/field-cooled behavior of the CoFe/(Co,Fe)O bilayers on MgO(100) and MgO(110) indicated that the FM CoFe spin orientations were affected by the different substrates used via exchange coupling to the AF (Co,Fe)O layer altered by MgO.
Low-regularity solutions of the periodic modified two-component Camassa-Holm equation
Authors: Xia Li-meng , Tian Lixin , Shen Caixia
Published: March 2013

This paper studies low-regularity periodic solutions of the modified two-component Camassa-Holm equation with initial value. We prove the existence and C0-well posedness of solutions.
Multilayer nanogranular films (Co40Fe40B20)50(SiO2)50/α-Si:H and (Co40Fe40B20)50(SiO2)50/SiO2: Magnetic properties
Authors: Komogortsev S. V. , Denisova E. A. , Iskhakov R. S. , Balaev A. D. , Chekanova L. A. , Kalinin Yu. E. , Sitnikov A. V.
Published: March 2013

Magnetic properties of multilayers, consisting of nanogranular (Co40Fe40B20)50(SiO2)50 layers as thin as magnetic granule diameter alternating the α-Si:H or SiO2 layers and the single layer film (Co40Fe40B20)50(SiO2)50 with the thickness much larger than the magnetic granule diameter are reported and compared. The thick single layer film is ferromagnetic but the multilayer film with the ultrathin granular layers and SiO2 spacer is superparamagnetic. This is interpreted as the result of increasing percolation threshold in the 2D granular media above 50% concentration of magnetic granules in the multilayer with the nonmagnetic and dielectric SiO2 spacer. The multilayer with the α-Si:H spacer is superparamagnetic at 300 K but it becomes ferromagnetic, when temperature is below 250 K. It is assumed to be resulted from the exchange interaction of magnetic granules through the semiconductor α-Si:H layers. The value of exchange interaction through the semiconductor spacer is estimated.
Tailoring of the soft magnetic property and uniaxial anisotropy of magnetostrictive films by interlayer
Authors: Wen Dandan , Bai Feiming , Wang Yicheng , Zhong Zhiyong , Zhang Huaiwu
Published: March 2013

Laminated amorphous FeSiBC films with various spacer layers, including Cu, Co0.45Cu0.55, Co0.8Cu0.2, and CoFe, were prepared in order to study the effect of interface structure and magnetic exchange interaction on the magnetic softness and uniaxial anisotropy of multilayered film. It is found that laminating FeSiBC film with thin nonmagnetic or weak magnetic spacers yields much lower coercivity and higher remanent magnetization than those with magnetic spacers. Optimal films with the desired properties of Hc ∼ 1.5 Oe, Mr/Ms = 95%, and Hk ∼ 16 Oe were obtained. Therefore, it is confirmed that the exchange interaction constant of spacer layer plays a more important role than that of interface structure. Furthermore, laminating FeSiBC with nonmagnetic layers only slightly changes magnetostrictive coefficient.
Hanle effect missing in a prototypical organic spintronic device
Authors: Riminucci Alberto , Prezioso Mirko , Pernechele Chiara , Graziosi Patrizio , Bergenti Ilaria , Cecchini Raimondo , Calbucci Marco , Solzi Massimo , Alek Dediu V.
Published: March 2013

We investigate spin precession (Hanle effect) in the prototypical organic spintronic giant magnetoresistance device La0.7Sr0.3MnO3/tris(8-hydroxyquinoline)/AlOx/Co. The Hanle effect is not observed in measurements taken by sweeping a magnetic field at different angles from the plane of the device. As possible explanations we discuss the tilting out of plane of the magnetization of the electrodes, exceptionally high mobility, or hot spots. Our results call for a greater understanding of spin injection and transport in such devices.
Individuality of breathing patterns in patients under noninvasive mechanical ventilation evidenced by chaotic global models
Authors: Letellier Christophe , Rodrigues Giovani G. , Muir Jean-François , Aguirre Luis A.
Published: March 2013

Autonomous global models based on radial basis functions were obtained from data measured from patients under noninvasive mechanical ventilation. Some of these models, which are discussed in the paper, turn out to have chaotic or quasi-periodic solutions, thus providing a first piece of evidence that the underlying dynamics of the data used to estimate the global models are likely to be chaotic or, at least, have a chaotic component. It is explicitly shown that one of such global models produces attractors characterized by a Horseshoe map, two models produce toroidal chaos, and one model produces a quasi-periodic regime. These topologically inequivalent attractors evidence the individuality of breathing profiles observed in patient under noninvasive ventilation.
Tuning graphene morphology by substrate towards wrinkle-free devices: Experiment and simulation
Authors: Lanza M. , Wang Y. , Bayerl A. , Gao T. , Porti M. , Nafria M. , Liang H. , Jing G. , Liu Z. , Zhang Y. , Tong Y. , Duan H.
Published: March 2013

Graphene grown by chemical vapor deposition can be used as the conductive channel in metal oxide semiconductor field effect transistors, metallic electrodes in capacitors, etc. However, substrate-induced corrugations and strain-related wrinkles formed on the graphene layer impoverish the properties of these devices by lowering the conductance and increasing their variability. Using the scanning electron microscopy, Auger electron spectroscopy, scanning tunneling microscopy, and atomic force microscopy, we investigated the morphology of as-grown and transferred graphene sheets on different substrates. We show that while the compressive strain (from the growth process) in the graphene sheet on flat substrates is minimized by generating wrinkles, and on rough substrates, it can be minimized by improving the graphene-substrate adhesion, leading to lower densities of wrinkles. This method paves the way to the design of wrinkle-free graphene based devices.
Network-based stochastic competitive learning approach to disambiguation in collaborative networks
Authors: Christiano Silva Thiago , Raphael Amancio Diego
Published: March 2013

Many patterns have been uncovered in complex systems through the application of concepts and methodologies of complex networks. Unfortunately, the validity and accuracy of the unveiled patterns are strongly dependent on the amount of unavoidable noise pervading the data, such as the presence of homonymous individuals in social networks. In the current paper, we investigate the problem of name disambiguation in collaborative networks, a task that plays a fundamental role on a myriad of scientific contexts. In special, we use an unsupervised technique which relies on a particle competition mechanism in a networked environment to detect the clusters. It has been shown that, in this kind of environment, the learning process can be improved because the network representation of data can capture topological features of the input data set. Specifically, in the proposed disambiguating model, a set of particles is randomly spawned into the nodes constituting the network. As time progresses, the particles employ a movement strategy composed of a probabilistic convex mixture of random and preferential walking policies. In the former, the walking rule exclusively depends on the topology of the network and is responsible for the exploratory behavior of the particles. In the latter, the walking rule depends both on the topology and the domination levels that the particles impose on the neighboring nodes. This type of behavior compels the particles to perform a defensive strategy, because it will force them to revisit nodes that are already dominated by them, rather than exploring rival territories. Computer simulations conducted on the networks extracted from the arXiv repository of preprint papers and also from other databases reveal the effectiveness of the model, which turned out to be more accurate than traditional clustering methods.
The insulator-to-metal transition of Co hyperdoped crystalline silicon
Authors: Zhou Yurong , Liu Fengzhen , Song Xiaohui
Published: March 2013

Co hyperdoped crystalline silicon samples were prepared by the combination of ion implantation and pulsed laser melting techniques. The current–voltage curves of the heavily Co-implanted samples present a rectifying behavior, which is related to the contact between the Co implanted layer and the Si substrate. The temperature dependences of the resistances indicate that an insulator-to-metal transition probably happens in the low temperature range. The transition occurs in the Co concentration range of 3 × 1019 – 6 × 1020 cm−3, which corresponds to the Mott insulator-to-metal transition limit. The temperature dependences of the resistances are well fitted based on a simplified two-layer model consisting of an intermediate band layer and a substrate layer. The fitting intermediate band location is at about 0.51 eV below the conduction band edge of Si. The Co hyperdoped crystalline silicon is a kind of potential material for intermediate band solar cells.
Negative differential resistances in graphene double barrier resonant tunneling diodes
Authors: Song Yu , Wu Han-Chun , Guo Yong
Published: March 2013

We theoretically investigate negative differential resistance (NDR) of massless and massive Dirac Fermions in double barrier resonant tunneling diodes based on sufficiently short and wide graphene strips. The current-voltage characteristics calculated in a rotated pseudospin space show that the NDR feature only presents with appropriate structural parameters for the massless case, and the peak-to-valley current ratio can be enhanced exponentially by a tunable band gap. Remarkably, the lowest NDR operation window is nearly structure-free and can be almost solely controlled by a back gate, which may have potential applications in NDR devices with the operation window as a crucial parameter.
Electrode-plasma-driven radiation cutoff in long-pulse, high-power microwave devices
Authors: Rose D. V. , Miller C. L. , Portillo S. , Welch D. R.
Published: March 2013

The impact of electrode plasma dynamics on the radiation production in a high power microwave device is examined using particle-in-cell simulations. Using the design of a compact 2.4 GHz magnetically insulated line oscillator (MILO) as the basis for numerical simulations, we characterize the time-dependent device power and radiation output over a range of cathode plasma formation rates. These numerical simulations can self-consistently produce radiation characteristics that are similar to measured signals in long pulse duration MILOs. This modeling capability should result in improved assessment of existing high-power microwave devices and lead to new designs for increased radiation pulse durations.
Influence of extrinsic factors on accuracy of mobility extraction in graphene metal-oxide-semiconductor field effect transistors
Authors: Gon Lee Young , Ji Kim Yun , Goo Kang Chang , Cho Chunhum , Lee Sangchul , Jun Hwang Hyeon , Jung Ukjin , Hun Lee Byoung
Published: March 2013

Graphene has attracted attention because of its extraordinarily high mobility. However, procedures to extract mobility from graphene metal-oxide semiconductor transistors have not been systematically established because the accuracy of mobility value is affected by many extrinsic parameters. In this work, the influence of extrinsic parameters, such as contact resistance, transient charging effect, measurement temperature, and ambient on mobility are examined in order to provide a protocol capable of accurately assessing the mobility of graphene metal-oxide-semiconductor field effect transistors. Using a well controlled test protocol, the mobility of graphene is found to be temperature independent up to 450 K.
The Smurf ubiquitin ligases regulate tissue separation via antagonistic interactions with ephrinB1
Authors: Hwang Yoo-Seok , Lee Hyun-Shik , Kamata Teddy , Mood Kathleen , Cho Hee Jun , Winterbottom Emily , Ji Yon Ju , Singh Arvinder , Daar Ira O.
Published: March 2013

The formation of tissue boundaries is dependent on the cell–cell adhesion/repulsion system that is required for normal morphogenetic processes during development. The Smad ubiquitin regulatory factors (Smurfs) are E3 ubiquitin ligases with established roles in cell growth and differentiation, but whose roles in regulating cell adhesion and migration are just beginning to emerge. Here, we demonstrate that the Smurfs regulate tissue separation at mesoderm/ectoderm boundaries through antagonistic interactions with ephrinB1, an Eph receptor ligand that has a key role in regulating the separation of embryonic germ layers. EphrinB1 is targeted by Smurf2 for degradation; however, a Smurf1 interaction with ephrinB1 prevents the association with Smurf2 and precludes ephrinB1 from ubiquitination and degradation, since it is a substantially weaker substrate for Smurf1. Inhibition of Smurf1 expression in embryonic mesoderm results in loss of ephrinB1-mediated separation of this tissue from the ectoderm, which can be rescued by the coincident inhibition of Smurf2 expression. This system of differential interactions between Smurfs and ephrinB1 regulates the maintenance of tissue boundaries through the control of ephrinB protein levels.
Targeted decay of a regulatory small RNA by an adaptor protein for RNase E and counteraction by an anti-adaptor RNA
Authors: Göpel Yvonne , Papenfort Kai , Reichenbach Birte , Vogel Jörg , Görke Boris
Published: March 2013

Bacterial small RNAs (sRNAs) are well established to regulate diverse cellular processes, but how they themselves are regulated is less understood. Recently, we identified a regulatory circuit wherein the GlmY and GlmZ sRNAs of Escherichia coli act hierarchically to activate mRNA glmS, which encodes glucosamine-6-phosphate (GlcN6P) synthase. Although the two sRNAs are highly similar, only GlmZ is a direct activator that base-pairs with the glmS mRNA, aided by protein Hfq. GlmY, however, does not bind Hfq and activates glmS indirectly by protecting GlmZ from RNA cleavage. This complex regulation feedback controls the levels of GlmS protein in response to its product, GlcN6P, a key metabolite in cell wall biosynthesis. Here, we reveal the molecular basis for the regulated turnover of GlmZ, identifying RapZ (RNase adaptor protein for sRNA GlmZ; formerly YhbJ) as a novel type of RNA-binding protein that recruits the major endoribonuclease RNase E to GlmZ. This involves direct interaction of RapZ with the catalytic domain of RNase E. GlmY binds RapZ through a secondary structure shared by both sRNAs and therefore acts by molecular mimicry as a specific decoy for RapZ. Thus, in analogy to regulated proteolysis, RapZ is an adaptor, and GlmY is an anti-adaptor in regulated turnover of a regulatory small RNA.