bluuebunny/crossref_metadata_2025 huggingface dataset:
Weak localization and antilocalization of hole carriers in degenerate p-Ge1−xMnxTe
Authors: Lim S. T. , Hui L. , Bi J. F. , Teo K. L.
Published: December 2011

We have performed magnetotransport studies on p-type Ge0.7Mn0.3Te under hydrostatic pressure. The magnetoresistance (MR) is characterized by both positive and negative contributions, which can be described by the antilocalization and weak localization models, respectively. We report the temperature and pressure dependence of the spin-orbit, elastic and inelastic scattering times, as well as the coherence length in Ge0.7Mn0.3Te. The spin-orbit scattering time is found to be independent of pressure and temperature and it dominates over the inelastic scattering time leading to the observed positive MR. The phase coherent length is correlated to the inelastic scattering which is predominately due to electron-electron scattering.
Switching quantum transport in a three donors silicon fin-field effect transistor
Authors: Leti Guillaume , Prati Enrico , Belli Matteo , Petretto Guido , Fanciulli Marco , Vinet Maud , Wacquez Romain , Sanquer Marc
Published: December 2011

We switch the transport along different paths in a system constituted by a phosphorus donor in a silicon quantum dot in complementary metal-oxide-semiconductor technology, coupled with two donors at the source side. The standard Coulomb blockade pattern created by the transport through the D0 neutral state of an individual donor located in the channel of the device is modified by two additional randomly diffused nearby donors. By varying the control voltages, the fin-field effect transistor acts as a quantum device which may be used to control alternative current paths through different donors.
Cultural and Economic Complementarities of Spatial Agglomeration in the British Television Broadcasting Industry: Some Explorations
Authors: Cook Gary A S , Pandit Naresh R , Beaverstock Jonathan V
Published: December 2011

This paper considers the processes supporting agglomeration in the British television broadcasting industry. It compares and contrasts the insights offered by the cultural turn in geography and more conventionally economic approaches. It finds that culture and institutions are fundamental to the constitution of production and exchange relationships and also that they solve fundamental economic problems of coordinating resources under conditions of uncertainty and limited information. Processes at a range of spatial scales are important, from highly local to global, and conventional economics casts some light on which firms are most active and successful.
The Productive Role of ‘Quality of Place’: A Case Study of Fashion Designers in Toronto
Authors: Leslie Deborah , Brail Shauna
Published: December 2011

Within the urban economic development literature, there has been considerable debate concerning the role of ‘quality of place’ in attracting and retaining talent. Arguments have been polarized, however, between those suggesting that quality of place plays a key role in urban growth, and those arguing that jobs and production networks are more important. In this paper we reconcile the debates by emphasizing the productive function of quality of place. Drawing on a case study of fashion designers in Toronto, we examine the roles of diversity, tolerance, social services, and cultural dynamism in attracting and retaining talent, in fostering aesthetic experimentation, and in mediating some of the risks associated with cultural work.
Sustainable Lifestyles: Sites, Practices, and Policy
Authors: Barr Stewart , Shaw Gareth , Coles Tim
Published: December 2011

Proenvironmental behaviour change remains a high priority for many governments and agencies and there are now numerous programmes aimed at encouraging citizens to adopt sustainable forms of living. However, although programmes for addressing behaviour change in and around the home are well developed, there has been significantly less attention paid to activities beyond this site of practice. This is despite the environmental implications of consumption choices for leisure, tourism, and work-related activities. Through focusing on sites of practice as a key framing device, this paper uses data from a series of in-depth interviews to identify three major challenges for academics and practitioners concerned with understanding and promoting more environmentally responsible behaviour. First, attention must shift beyond the home as a site of environmental practice to consider the ways in which individuals respond to exhortations towards ‘greener’ lifestyles in other high-consumption and carbon-intensive settings, Second, in broadening the scope of environmental practice, policy makers need to revisit their reliance on segmentation models and related social marketing approaches. This is in the light of data that suggest those with strong environmental commitments in the home are often reluctant to engage in similar commitments in other sites of practice. Third, researchers and policy makers therefore need to move beyond the traditional ‘siting’ of environmental practice towards a spatially sophisticated conceptualisation that accounts for the multiple settings of consumption through mapping the relationships that exist between sites of practice.
Researching Air-Conditioning Addiction and Ways of Puncturing Practice: Professional Office Workers and the Decision to Go outside
Authors: Hitchings Russell
Published: December 2011

Though many people around the world now spend much of their time surrounded by bodies of controlled ambient air indoors, we still know relatively little about the subjectivities involved. Some have deployed the idea of air-conditioning addiction. Others emphasise the enjoyable sensations associated with temporary escape. The research described in this paper sought to add some empirical depth to these discussions by combining theories of social practice with a programme of serial interviews to examine how a sample of city professionals felt about the long periods they spent inside air-conditioned offices. The rationale was that, through these means, it should be possible to identify ways of disrupting otherwise habitual indoor existences and thereby discourage people from becoming increasingly reliant upon ambient conditions that are environmentally costly to supply. Describing their passage through a typical working day, this paper focuses on the moments when it might have occurred to them to spend time outside and how certain mental and material elements combined to impede the arrival of this decision. This exercise is used to draw out suggestions about how a better relationship between professional office workers and the everyday outdoors could be encouraged. The broader conclusion is that contextual studies which examine how places and practices produce decisions, instead of assuming individual people merely make them, have their part to play in fostering positive social futures.
Event and Anticipation: UK Civil Contingencies and the Space—Times of Decision
Authors: Adey Peter , Anderson Ben
Published: December 2011

What is the relation between security and a decision? How should decisions be taken as events unfold in unpredictable, aleatory, ways? And how are decisions made and constituted in particular and therefore differential security contexts? The paper draws on observations of ‘strategic’ exercises in UK Civil Contingencies, sites in which ‘multiagency’ responders take decisions in relation to the events that make up a range of crises, breakdowns, and interruptions. UK Civil Contingencies has a complicated relation with decision which challenges the predominance of approaches which prioritise the ‘sovereign decision’ as a preemptive act. On the one hand, the dream of emergency planners is of a decentred anticipatory system without the need for the event of decision, in which a distributed set of responders are primed to snap into action at the onset of an event and to follow protocols for how to connect and act together. On the other hand, and faced with the contingency of events and the mutability of the response network, decision is not erased, automated, or deferred but proliferates and, sometimes, is very difficult to make. Decisions have to constantly be taken about who to act with and how to act when faced with what the event could become: that is, when faced by the event's potential and, importantly, the complexity of response. In the paper we explore the relation between security and decision by outlining how the ‘exercise’ functions within emergency planning as a privileged site for the staging and performing of decisions.
“I'm on Autopilot, I Just Follow the Route”: Exploring the Habits, Routines, and Decision-Making Practices of Everyday Urban Mobilities
Authors: Middleton Jennie
Published: December 2011

Much urban and transport policy is based on a series of assumptions relating to predefined journeys informed by rational decision making. For example, the dominant focus of urban pedestrian policy is how the built environment is the primary influence on a person's decision to walk, with these decisions being made at a specific time and place somehow outside the practice of walking. Little attention is given to the importance of the processual and experiential dimensions of walking itself. This paper considers the ways in which journeys into, and through, the city unfold. Specific attention is drawn to how forms of habitual performance, such as practical knowledge and embodied habits and routines, assist in engaging with everyday urban movements. In the context of in-depth research conducted in London, the paper explores the habits and routines of urban pedestrian mobilities such as the daily commute, and in so doing, highlights the complexity and ongoing reconfiguration of these journeys beyond analysis informed by ‘rational’ intention. In contrast to much transport research that conceives of habit as an external force that somehow obstructs more positive sustainable travel behaviour, discussion focuses on the significance of how everyday urban walking unfolds. It is argued that this form of engagement makes it possible to understand habit as situated and part and parcel of the sequentially organised and occasioned performance of journeys on foot. This, in turn, enables the transformative potential of habitual behaviour to be realised. Throughout the paper consideration is given to specific narratives of everyday urban mobilities; the significance of how such practices are actually ‘talked about’; and how these accounts matter in engaging with the experiential dimensions of urban movement.
A Simulation-Based Study of Geographically Weighted Regression as a Method for Investigating Spatially Varying Relationships
Authors: Páez Antonio , Farber Steven , Wheeler David
Published: December 2011

Large variability and correlations among the coefficients obtained from the method of geographically weighted regression (GWR) have been identified in previous research. This is an issue that poses a serious challenge for the utility of the method as a tool to investigate multivariate relationships. The objectives of this paper are to assess: (1) the ability of GWR to discriminate between a spatially constant processes and one with spatially varying relationships; and (2) to accurately retrieve spatially varying relationships. Extensive numerical experiments are used to investigate situations where the underlying process is stationary and nonstationary, and to assess the degree to which spurious intercoefficient correlations are introduced. Two different implementations of GWR and cross-validation approaches are assessed. Results suggest that judicious application of GWR can be used to discern whether the underlying process is nonstationary. Furthermore, evidence of spurious correlations indicates that caution must be exercised when drawing conclusions regarding spatial relationships retrieved using this approach, particularly when working with small samples.
Does Cultural Policy Matter in Public-Art Production? The Netherlands and Flanders Compared, 1945–Present
Authors: Zebracki Martin
Published: December 2011

Cultural policy has produced divergent intentions underlying the direction of public art since its advent in Western Europe in 1945. Literature has feebly demonstrated the extent to which differentialities in cultural policy have affected the production of public artworks over time and space. This paper fills this gap as regards Amsterdam and Ghent, cities that are situated in different national institutional contexts. It shows dissimilarity—in that one finds a relatively higher number of public artworks, more spatially dispersed and more diversified public artworks in Amsterdam than in Ghent, which is particularly a result of institutional differences—and similarity between these cities, in terms of initiatives by local communities and arts actors, irrespective of the local policy context. These results provide insight into policy concern with public-art production and the everyday practices and cultural traditions that underpin it.
Guest Editorial: The Space—Times of Decision Making
Authors: McCormack Derek P , Schwanen Tim
Published: December 2011

By way of an extended introduction to a theme issue on the space–times of decision making, this paper pursues two objectives. We first review some of the ways in which geographers—and especially economic geographers—have examined decision making over the past decades, showing that previous engagements with the decision are informed primarily by thinking from economics, psychology, and certain strands of sociology. Drawing on a wider range of intellectual resources, we then outline eight propositions that might guide future research by geographers and others into the space–times of decision making. These propositions help us to move beyond the idea that the decision is a singular moment abstracted from the context within which it takes place and undertaken by a discrete actor or set of actors. Instead the decision is understood as a differentiated, affectively registered, transformative, and ongoing actualisation of potential against a horizon of undecidability in which past, present, and future fold together in complex ways. A number of research questions follow from the outlined propositions: these pertain to the sites and techniques of decision making, its relationships to the governing of life, and our own decision-making practices as academics.
Dynamic visualizations of language change
Authors: Hilpert Martin
Published: December 2011

This paper uses diachronic corpus data to visualize language change in a dynamic fashion. Bivariate and multivariate data sets form the input for so-called motion charts, i.e. series of diachronically ordered scatterplots that can be viewed in sequence. Based on data from COHA (Davies 2010), two case studies illustrate recent changes in American English. The first study visualizes change in a diachronic analysis of ambicategorical nouns and verbs such as hope or drink; the second study shows structural change in the behavior of complement-taking predicates such as expect or remember. Whereas motion charts are typically used to represent bivariate data sets, it is argued here that they are also useful for the analysis of multivariate data over time. The present paper submits multivariate diachronic data to a multi-dimensional scaling analysis. Viewing the resulting data points in separate time slices offers a holistic and intuitive representation of complex linguistic change.
English adjectives in -like, and the interplay of collocation and morphology
Authors: Moon Rosamund
Published: December 2011

This paper presents a corpus-based study of English denominal adjectives in -like. Starting with semantic aspects, including the relationship between N-like and like an N, it then reports on the productivity of -like adjectives by discussing the kinds of nouns to which -like is added, along with the distributions of individual formations in the Bank of English corpus. It next draws attention to the marked collocational patterns in which -like adjectives occur. These relate both to sets of items collocating with individual -like adjectives, and to subsets of -like adjectives collocating with individual nouns. There are implications in these bidirectional collocational patterns, it is argued, for studies of productivity and lexicalization: in particular that collocational constraints may exist at the level of morpheme, not just at the level of word or phrase.
Developing communities of learners
Authors: Inman Sally
Published: December 2011

This article describes some of the findings of an evaluation of a ‘cross‐ curricular’ digital media arts project for Year 8 students at Lister Community School in the London Borough of Newham. The project was designed to provide opportunities for a thematic curriculum in which quality learning encompassing both independent and collaborative learning was central. The project was also aimed at fostering a range of knowledge, skills and attitudes around students' personal and social development. The findings of the evaluation suggest that the project was successful in a number of ways: in enhancing students' personal and social development; in developing a community of learners in which learning was shared between teachers and students; in developing students' confidence and skills in their own learning; and in providing models of a more integrated and thematic curriculum.
The teaching and learning of pupils in low‐attainment sets
Authors: Dunne Máiréad , Humphreys Sara , Dyson Alan , Sebba Judy , Gallannaugh Frances , Muijs Daniel
Published: December 2011

This study explored the ways in which schools addressed the needs of pupils in low‐attainment class groups, or sets, in the context of multiple and contrary government policy directives and inconclusive research findings about setting. In this article we have focused on school and classroom practices as well as the organisational processes through which low‐attaining pupils were identified, grouped and reviewed within schools. The empirical data reported here predominantly refer to case studies involving classroom observations and interviews with teachers, pupils and other staff in 13 schools – both primary and secondary – from four local authorities (LAs).

In the latter part of the article, however, we also draw on survey data collected from a larger sample of schools in 12 LAs in England. Although the study found ample evidence of innovative school practices and efforts by individual teachers aimed at optimising the learning opportunities for children in low‐attainment class groups, the findings also raise important questions about some of the processes of set allocation, the lack of mobility between sets, and the over‐representation of particular social groups in low‐attainment classes. We conclude with a discussion of the implications for equity and inclusion that moves beyond an emphasis on classroom practice to include questions about the in‐school processes of social selection and educational mobility for pupils identified as low‐attaining.
Happiness matters: towards a pedagogy of happiness and well‐being
Authors: Scoffham Stephen , Barnes Jonathan
Published: December 2011

The role of the emotions in learning has long been acknowledged but is often overlooked. This article considers the impact one particular emotion, happiness, has on learning and the school curriculum. Recent reports have drawn attention to the importance of happiness (or the lack of it) by highlighting concerns about childhood well‐being. At the same time, there is increasing evidence from psychology and neuroscience to suggest that periods of happiness are linked to personal growth, health and development. When we are happy it seems we are more likely to be receptive to outside stimuli than when we are sad or distressed. Happiness also makes us more disposed to engage in creative endeavour, which is itself another source of fulfilment. Positive psychologists argue that rather than being fixed, happiness, optimism and other positive traits can be learnt. We offer evidence from our own professional experience in teaching to corroborate these claims and to extend the debate about the relevance of affective neuroscience to education. In conclusion, we consider how a focus on happiness might underpin a positive approach to curriculum reform.
Estimating mercury concentrations and loads from four western Lake Superior watersheds using continuous in-stream turbidity monitoring
Authors: Ruzycki E. M. , Axler R. P. , Henneck J. R. , Will N. R. , Host G. E.
Published: December 2011

Many streams along the Minnesota coast of Lake Superior have been listed as impaired from either high turbidity or high fish mercury concentrations or both. Both turbidity and total mercury have been shown to be strongly correlated to total suspended sediment in many disturbed watersheds. Turbidity and total mercury concentrations and loads were estimated in four western Lake Superior watersheds from 2005–2006 using automated in-stream turbidity measurements. Regression models were developed relating this near-continuous turbidity data to grab sample measures of mercury during differing flow regimes. Total mercury values ranged from 1 to 28 ng l−1 throughout the open water season and showed a close relationship to total suspended sediment (r2 = 0.85, n = 23; p < 0.001) and a less robust but still significant relationship with turbidity (r2 = 0.40, n = 34; p < 0.001) for all four streams. Mercury loads to Lake Superior were estimated to range from 8 to 97 g yr−1 with watershed yields ranging from 0.5 to 4.3 μg m−2 yr−1. Continuous turbidity monitoring appears to be a reasonable surrogate for both suspended sediment and total mercury concentration, providing information when manual sample collection is cost-prohibitive or logistically difficult, and across a wide range of flows.
Monitoring land cover change in the Lake Superior basin
Authors: Hollenhorst T. P. , Johnson L. B. , Ciborowski J.
Published: December 2011

Consistent, repeatable and broadly applicable land use, land cover data is needed across the Lake Superior basin to facilitate ecosystem condition assessment and trend analysis. Such a data set collected regularly through time could inform and focus field monitoring efforts, and help prioritize restoration and mitigation efforts. Unfortunately, few data sets exist that are bi-nationally consistent in time, classification method, or resolution. To this end, we integrated land cover data across both the Canadian (Ontario Provincial Land Cover data) and US portions (National Land Cover Data) of the Lake Superior basin for two time steps (approximately 1992 and 2001) roughly one decade apart. After harmonizing landcover classes across the two datasets we compared the explicit amount and relative amount (total hectares and proportion of each area as percents) for each of the common land cover classes that occurred across the two time steps for the entire Lake Superior basin, for the U.S. portion of the Lake Superior basin only, and for the Canadian portion of the Lake Superior basin only. We also compared land cover change for the entire basin within a 1 km and a 10 km buffer of the Great Lakes shoreline. We then summarized and compared these land cover types for each time period across a common set of watersheds derived from elevation data (Hollenhorst et al., 2007) for the entire Lake Superior basin. This allowed us to identify and quantify the types of change occurring generally across the entire basin, more specifically across both the U.S. and Canadian portions of the basin, and more explicitly for near coastal areas and watersheds across the entire basin. Noteworthy changes were detected across the basin, particularly an increase in mixed forest types and a corresponding decrease in coniferous forest types.
An integrated approach to assessing multiple stressors for coastal Lake Superior
Authors: Niemi Gerald J. , Reavie Euan D. , Peterson Gregory S. , Kelly John R. , Johnston Carol A. , Johnson Lucinda B. , Howe Robert W. , Host George E. , Hollenhorst Tom P. , Danz Nicholas P. , Ciborowski Jan J. H. , Brown Terry N. , Brady Valerie J. , Axler Richard P.
Published: December 2011

Biological indicators can be used both to estimate ecological condition and to suggest plausible causes of ecosystem degradation across the U.S. Great Lakes coastal region. Here we use data on breeding bird, diatom, fish, invertebrate, and wetland plant communities to develop robust indicators of ecological condition of the U.S. Lake Superior coastal zone. Sites were selected as part of a larger, stratified random design for the entire U.S. Great Lakes coastal region, covering gradients of anthropogenic stress defined by over 200 stressor variables (e.g. agriculture, altered land cover, human populations, and point source pollution). A total of 89 locations in Lake Superior were sampled between 2001 and 2004 including 31 sites for stable isotope analysis of benthic macroinvertebrates, 62 sites for birds, 35 for diatoms, 32 for fish and macroinvertebrates, and 26 for wetland vegetation. A relationship between watershed disturbance metrics and 15N levels in coastal macroinvertebrates confirmed that watershed-based stressor gradients are expressed across Lake Superior's coastal ecosystems, increasing confidence in ascribing causes of biological responses to some landscape activities. Several landscape metrics in particular—agriculture, urbanization, human population density, and road density—strongly influenced the responses of indicator species assemblages. Conditions were generally good in Lake Superior, but in some areas watershed stressors produced degraded conditions that were similar to those in the southern and eastern U.S. Great Lakes. The following indicators were developed based on biotic responses to stress in Lake Superior in the context of all the Great Lakes: (1) an index of ecological condition for breeding bird communities, (2) diatom-based nutrient and solids indicators, (3) fish and macroinvertebrate indicators for coastal wetlands, and (4) a non-metric multidimensional scaling for wetland plants corresponding to a cumulative stress index. These biotic measures serve as useful indicators of the ecological condition of the Lake Superior coast; collectively, they provide a baseline assessment of selected biological conditions for the U.S. Lake Superior coastal region and prescribe a means to detect change over time.
Microbial ecology of Lake Superior Bacteria and Archaea: An overview
Authors: Reed Andrew J. , Hicks Randall E.
Published: December 2011

Microorganisms are ubiquitously distributed in all types of lakes of varying trophic state. They play an important role in aquatic ecosystems, performing the tasks of decomposing organic matter, cycling nutrients and forming the base of microbial food webs. Bacterial abundance is generally lower in ultraoligotrophic Lake Superior than in other great lakes, ranging from 0.06 to 0.07 × 106 cells l−1 in offshore areas to 1.9 × 106 cells l−1 at nearshore stations along the north shore of this lake. Bacterioplankton cells are usually less abundant than in Lake Michigan and rarer than in more eutrophic Lake Erie. Heterotrophic bacterial production ranges from 0.02 to 0.66 mg C m−3 h−1 in the western arm of Lake Superior, which is generally lower than in the other Laurentian Great Lakes. There do not appear to be consistent gradients of bacterial abundance and production from nearshore to offshore areas and there are few studies about microbial populations and the diversity of microbial communities in Lake Superior. Yet, a better understanding of Lake Superior's smallest inhabitants – the prokaryotes– would improve our knowledge about how this lake functions and help us to better understand and possibly resolve new issues that are emerging. This paper reviews the current status of microbiological research in Lake Superior, emphasizing recent work on picoplanktonic Bacteria and Archaea, and attempts to place these findings and current ecological issues within a historical framework.
Synergy between the ESCRT-III complex and Deltex defines a ligand-independent Notch signal
Authors: Hori Kazuya , Sen Anindya , Kirchhausen Tom , Artavanis-Tsakonas Spyros
Published: December 2011

The Notch signaling pathway defines a conserved mechanism that regulates cell fate decisions in metazoans. Signaling is modulated by a broad and multifaceted genetic circuitry, including members of the endocytic machinery. Several individual steps in the endocytic pathway have been linked to the positive or negative regulation of the Notch receptor. In seeking genetic elements involved in regulating the endosomal/lysosomal degradation of Notch, mediated by the molecular synergy between the ubiquitin ligase Deltex and Kurtz, the nonvisual β-arrestin in Drosophila, we identified Shrub, a core component of the ESCRT-III complex as a key modulator of this synergy. Shrub promotes the lysosomal degradation of the receptor by mediating its delivery into multivesicular bodies (MVBs). However, the interplay between Deltex, Kurtz, and Shrub can bypass this path, leading to the activation of the receptor. Our analysis shows that Shrub plays a pivotal rate-limiting step in late endosomal ligand-independent Notch activation, depending on the Deltex-dependent ubiquitinylation state of the receptor. This activation mode of the receptor emphasizes the complexity of Notch signal modulation in a cell and has significant implications for both development and disease.
The ‘recycling trap’: a generalized explanation of discharge runaway in high-power impulse magnetron sputtering
Authors: Anders A , Čapek J , Hála M , Martinu L
Published: December 2011

Contrary to paradigm, magnetron discharge runaway cannot always be related to self-sputtering. We report here that the high density discharge can be observed with all conducting targets, including low sputter yield materials such as carbon. Runaway to a high density discharge is therefore generally based on self-sputtering in conjunction with the recycling of gas atoms in the magnetic field-affected pre-sheath. A generalized runaway condition can be formulated, offering a pathway to a time-dependent model for high-power impulse magnetron sputtering that includes rarefaction and an explanation for the termination of runaway.
A new approach to fabricate Nd2Fe14B/α-Fe nanocomposite precursors by selective removal of Nd from Nd–Fe–B powders
Authors: Nie Junwu , Du Juan , Liu Jingjing , Yin Wenzong , Zhang Jian , Yan Aru
Published: December 2011

A facile method based on α-Fe self-supply was developed to get exchange coupling Nd2Fe14B/α-Fe nanocomposites. A small amount of neodymium was removed from the Nd2Fe14B compound in Nd-rich melt-spun powders by chemical treatment with NH4Cl and CH3COOH acid solution and α-Fe remained. Full dense anisotropic Nd2Fe14B/α-Fe magnets were prepared via hot pressing and hot deformation techniques using the as-prepared powders. The evolution of composition and phase was investigated. The best energy product (BH)max of the Nd2Fe14B/α-Fe magnets was 47.5 MG Oe, 5% higher than that of a single-phase Nd2Fe14B magnet. The α-Fe phase, which was precipitated on the edge of the Nd2Fe14B particle, contributed to the exchange coupling effect and the enhancement of remanence (B
r). This method can be applied as a new strategy to prepare next generation nanocomposite magnets with good magnetic properties.
On the optical properties of undoped and rare-earth-doped yttrium aluminium garnet single crystals
Authors: Varney C R , Mackay D T , Reda S M , Selim F A
Published: December 2011

Optical absorption and photoluminescence (PL) measurements were performed on single crystals of undoped Y3Al5O12 (YAG) and a number of rare-earth-doped YAG to study the effect of dopant type and concentration, growth atmosphere, post-growth annealing and UV irradiation on the optical properties of YAG crystals. The presence of hydrogen in the growth atmosphere was found to be essential for enhancing the incorporation of Ce ions in the Ce3+ state in Ce-doped YAG (Ce : YAG). Annealing in air was shown to have no effect on the PL emission of Ce : YAG crystals. An absorption peak around 256 nm was observed in the undoped YAG and Ce : YAG crystals after air anneal at 1200 °C. Optical absorption and annealing experiments support the association of the 256 nm peak with Fe impurities and oxygen ions. UV irradiation modifies the valency of impurities and generates electronic defects leading to an increase in the optical density of YAG crystals. Optimizing the growth and annealing conditions is critical in order to develop Ce : YAG single crystals as efficient scintillators.
Fluid simulation of the phase-shift effect in hydrogen capacitively coupled plasmas: II. Radial uniformity of the plasma characteristics
Authors: Zhang Yu-Ru , Xu Xiang , Bogaerts Annemie , Wang You-Nian
Published: December 2011

A two-dimensional fluid model, including the full set of Maxwell equations, has been developed and applied to investigate the effect of a phase shift between two power sources on the radial uniformity of several plasma characteristics in a hydrogen capacitively coupled plasma. This study was carried out at various frequencies in the range 13.56–200 MHz. When the frequency is low, at 13.56 MHz, the plasma density is characterized by an off-axis peak when both power sources are in-phase (φ = 0), and the best radial uniformity is obtained at φ = π. This trend can be explained because the radial nonuniformity caused by the electrostatic edge effect can be effectively suppressed by the phase-shift effect at a phase difference equal to π. When the frequency rises to 60 MHz, the plasma density profiles shift smoothly from edge-peaked over uniform to centre-peaked as the phase difference increases, due to the pronounced standing-wave effect, and the best radial uniformity is reached at φ = 0.3π. At a frequency of 100 MHz, a similar behaviour is observed, except that the maximum of the plasma density moves again towards the radial edge at the reverse-phase case (φ = π), because of the dominant skin effect. When the frequency is 200 MHz, the bulk plasma density increases significantly with increasing phase-shift values, and a better uniformity is obtained at φ = 0.4π. This is because the density in the centre increases faster than at the radial edge as the phase difference rises, due to the increasing power deposition P

z
in the centre and the decreasing power density P

r
at the radial edge. As the phase difference increases to π, the maximum near the radial edge becomes obvious again. This is because the skin effect has a predominant influence on the plasma density under this condition, resulting in a high density at the radial edge. Moreover, the axial ion flux increases monotonically with phase difference, and exhibits similar profiles to the plasma density. The calculation results illustrate that the radial uniformity of the various plasma characteristics is strongly dependent on the applied frequency and the phase shift between both power sources, which is important to realize, for controlling the uniformity of the plasma etch and deposition processes.
Evidence of ferroelectricity in SrFeO3−δ
Authors: Manimuthu P , Venkateswaran C
Published: December 2011

Perovskite SrFeO3−δ belongs to the Ruddlesden–Popper class of system exhibiting interesting electronic and magnetic properties. Nanocrystalline SrFeO3−δ synthesized successfully by the thermal decomposition method has the cubic phase as confirmed from x-ray diffraction. The non-stoichiometric nature is confirmed from the selected area electron diffraction pattern. Oxygen stoichiometry, which plays an important role in determining the physical properties, was found to be 2.91 from the iodometric titration. Mössbauer measurement reveals paramagnetic behaviour and suggests mixed valence state of Fe. Relaxor type ferroelectricity is evident from the dielectric plots, which is also reflected in the thermal study. Relaxor ferroelectric behaviour is reported for the first time in SrFeO2.91, arising due to mixed valency of Fe ion.
GEO-MIX-SELF calculations of the elastic properties of a textured graphite sample at different hydrostatic pressures
Authors: Matthies Siegfried
Published: December 2011

The recently developed GEO-MIX-SELF approximation (GMS) is applied to interpret the pressure dependence of the longitudinal ultrasonic wave velocities in a polycrystalline graphite sample that has already been investigated in a wide range of experimental contexts. Graphite single crystals have extremely anisotropic elastic properties, making this sample a challenging test to demonstrate the potential of the GMS method. GMS combines elements of well known self-consistent algorithms and of the geometric mean approximation. It is able to consider mixtures of different polycrystalline phases, each with its own nonspherical grain shape and preferred orientation (texture). Pores and `cracks', typical for bulk graphite, are modeled as phases with `empty' grains. The pressure dependence (up to 150 MPa) of the experimental wave velocities can be well explained using the known texture of the sample by fitting the shape parameters and volume fractions of the graphite grains, cracks and spherical pores. The pressure dependence of these parameters describes a reasonable scenario for the closing of the cracks and pores with increasing pressure.
Design and application of a microfluidic device for protein crystallization using an evaporation-based crystallization technique
Authors: Yu Yong , Wang Xuan , Oberthür Dominik , Meyer Arne , Perbandt Markus , Duan Li , Kang Qi
Published: December 2011

A new crystallization system is described, which makes it possible to use an evaporation-based microfluidic crystallization technique for protein crystallization. The gas and water permeability of the used polydimethylsiloxane (PDMS) material enables evaporation of the protein solution in the microfluidic device. The rates of evaporation are controlled by the relative humidity conditions, which are adjusted in a precise and stable way by using saturated solutions of different reagents. The protein crystals could nucleate and grow under different relative humidity conditions. Using this method, crystal growth could be improved so that approximately 1 mm-sized lysozyme crystals were obtained more successfully than using standard methods. The largest lysozyme crystal obtained reached 1.57 mm in size. The disadvantage of the good gas permeability in PDMS microfluidic devices becomes an advantage for protein crystallization. The radius distributions of aggregrates in the solutions inside the described microfluidic devices were derived fromin situdynamic light scattering measurements. The experiments showed that the environment inside of the microfluidic device is more stable than that of conventional crystallization techniques. However, the morphological results showed that the protein crystals grown in the microfluidic device could lose their morphological stability. Air bubbles in microfluidic devices play an important role in the evaporation progress. A model was constructed to analyze the relationship of the rates of evaporation and the growth of air bubbles to the relative humidity.
Spatial distribution of the absorption factor for an infinite cylindrical sample used with a two-dimensional area detector
Authors: Sulyanov Sergei , Gogin Andrei , Boysen Hans
Published: December 2011

Specialized software has been developed to calculate the absorption factor for the infinite-cylinder transmission Debye–Scherrer geometry (including inclined beams) to be used with two-dimensional area powder pattern registration. The diffracted beams are defined by the direction cosines in the laboratory Cartesian coordinate system. Modern two-dimensional area detectors have a large number of pixels, so an interpolation is made by the triangulation procedure to save computer time. The absorption correction is allowed for so that the intensity in each pixel is reduced on the same scale and the final diffraction-angle-dependent intensity,I(2θ), does not require any further absorption correction.
A two-dimensional waveguide beam for X-ray nanodiffraction
Authors: Krywka Christina , Neubauer Henrike , Priebe Marius , Salditt Tim , Keckes Jozef , Buffet Adeline , Roth Stephan Volkher , Doehrmann Ralph , Mueller Martin
Published: December 2011

The micro- and nanofocus X-ray scattering (MINAXS) beamline of PETRA III is equipped with two consecutively arranged endstations, the last of which is the nanofocus endstation. The first in-beam commissioning of the experimental equipment was successfully performed at the end of 2010, using two-dimensionally confining hard X-ray silicon waveguides with cross sections of 50 nm × 50 µm to 50 nm × 2 µm for nanobeam generation. A full characterization of the waveguide-generated beams was performed, giving values for the beam geometries, the transmission efficiencies of the waveguides and absolute fluxes. Along with these results a detailed description of the setup is presented in this paper. A first high-resolution nanodiffraction experiment on a nanocrystalline TiN hard coating was performed to verify the resolution of the nanodiffraction setup and to reveal the local gradients across the blasted TiN coating. In conclusion, the main concern is the availability of the nanobeam, how it was generated and the fact that a beam out of a two-dimensionally confining waveguide was used for diffraction experiments for the first time.
X-ray and neutron attenuation correction factors for spherical samples
Authors: Zeidler Anita
Published: December 2011

A method is derived to calculate the attenuation correction factors for elastic or inelastic X-ray or neutron scattering experiments using a spherical sample. The method can be applied to a sphere that is either fully or partially illuminated by an incident beam of rectangular cross-sectional area. The required input parameters are the energy-dependent attenuation coefficients, the radius of the sphere and the dimensions of the incident beam. In-plane scattering is assumed.
Contrast matching of an Si substrate with polymer films by anomalous dispersion at the SiKabsorption edge
Authors: Okuda Hiroshi , Takeshita Kohki , Ochiai Shojiro , Kitajima Yoshinori , Sakurai Shinichi , Ogawa Hiroki
Published: December 2011

Anomalous dispersion at the SiKabsorption edge has been used to control the reflection from the interface between a film and an Si substrate, which otherwise complicates the nanostructure analysis of such a film, particularly for the soft-matter case, in grazing-incidence small-angle scattering. Such a reflectionless condition has been chosen for a triblock copolymer thin film, and two-dimensional grazing-incidence small-angle scattering patterns were obtained without the effect of the reflection. The present approach is useful for analysing nanostructures without introducing complicated corrections arising from the reflection.
Characterization of a Par j 1/Par j 2 mutant hybrid with reduced allergenicity for immunotherapy of Parietaria allergy
Authors: Bonura A. , Passantino R. , Costa M. A. , Montana G. , Melis M. , Luisa Bondì M. , Butteroni C. , Barletta B. , Corinti S. , Felice G. Di , Colombo P.
Published: December 2011

Background

Parietaria pollen is one of the major cause of pollinosis in the southern Europe. Specific immunotherapy is the only treatment able to modify the natural outcome of the disease restoring a normal immunity against allergens.

Methods

We designed a recombinant molecule (PjEDloop1) comprised of genetic‐engineered variants of the major allergens of the Parietaria pollen (Par j 2/Par j 1). Purity and chemical–physical properties of the derivative were analysed by RP‐HPLC chromatography and Photon Correlation Spectroscopy. Immunological activity was evaluated by means of Western blotting, ELISA inhibition and PBMC proliferation assay in 10 Parietaria allergic patients. Basophil activation was studied in six subjects. The immunogenicity of the hybrid was studied looking at the immune responses induced in a mouse model of sensitization.

Results

The PjEDloop1 hybrid was produced as a purified recombinant protein with high stability in solution. Western blot, ELISA inhibition and basophil activation test showed that the PjEDloop1 displays a remarkable reduced IgE binding and anaphylactic activity. CD3 reactivity was conserved in all patients. Mice immunization with the rPjEDloop1 induced antibodies and T cell responses comparable to that obtained by the wild type allergens. Such antibodies shared the specificities to rPar j 1 and rPar j 2 with human IgE antibodies.

Conclusion

Our results demonstrated that a mutant hybrid expressing genetically engineered forms of the major P. judaica allergens displayed reduced allergenicity and retained T cell reactivity for the induction of protective antibodies in vaccination approaches for the treatment of Parietaria pollinosis.
Serum sclerostin levels were positively correlated with fat mass and bone mineral density in Central South Chinese postmenopausal women
Authors: Sheng Zhifeng , Tong Dejun , Ou Yangna , Zhang Hongbin , Zhang Zhimin , Li Shuang , Zhou Jianlin , Zhang Jian , Liao Eryuan
Published: December 2011

Objectives  To investigate the relationship between serum sclerostin level, body composition, and bone mineral density (BMD) in central south Chinese postmenopausal women.

Methods  A cross‐sectional study was conducted on 260 healthy central southern Chinese postmenopausal women with vs without osteoporosis, aged 50–76 years old. Dual X‐ray absorptiometry was used to measure the bone mineral content and BMD of the whole body, lumbar spine and left femur, and total body soft tissue composition. Serum sclerostin levels were measured by a quantitative sandwich enzyme‐linked immunosorbent assay.

Results  Compared with women without osteoporosis, osteoporotic women had a significantly lower level of serum sclerostin (P = 0·001). Serum sclerostin levels were positively correlated with body weight, Ponderal index and fat mass. There was a positive correlation with the BMD of both the whole body and at various sites (P < 0·05), even after controlling for age, age at menopause, height and body weight. Multiple linear stepwise regression analysis showed that serum sclerostin level was the most significant determinant of both whole‐body and lumbar spine BMD, compared with age, age at menopause, fat mass and lean mass. Age had similar impact as serum sclerostin on hip BMD.

Conclusions  This study showed that in central south Chinese postmenopausal women, serum sclerostin is lower in women with osteoporosis than without. Serum sclerostin is positively correlated with fat mass and BMD for the whole body, lumbar spine and hip.