bluuebunny/crossref_metadata_2025 huggingface dataset:
Planning a Multi‐site, Complex Intervention for Homeless People with Mental Illness: The Relationships Between the National Team and Local Sites in Canada's At Home/Chez Soi Project
Authors: Nelson Geoffrey , Macnaughton Eric , Goering Paula , Dudley Michael , O'Campo Patricia , Patterson Michelle , Piat Myra , Prévost Natasha , Strehlau Verena , Vallée Catherine
Published: September 2012

This research focused on the relationships between a national team and five project sites across Canada in planning a complex, community intervention for homeless people with mental illness called At Home/Chez Soi, which is based on the Housing First model. The research addressed two questions: (a) what are the challenges in planning? and (b) what factors that helped or hindered moving project planning forward? Using qualitative methods, 149 national, provincial, and local stakeholders participated in key informant or focus group interviews. We found that planning entails not only intervention and research tasks, but also relational processes that occur within an ecology of time, local context, and values. More specifically, the relationships between the national team and the project sites can be conceptualized as a collaborative process in which national and local partners bring different agendas to the planning process and must therefore listen to, negotiate, discuss, and compromise with one another. A collaborative process that involves power‐sharing and having project coordinators at each site helped to bridge the differences between these two stakeholder groups, to find common ground, and to accomplish planning tasks within a compressed time frame. While local context and culture pushed towards unique adaptations of Housing First, the principles of the Housing First model provided a foundation for a common approach across sites and interventions. The implications of the findings for future planning and research of multi‐site, complex, community interventions are noted.
Annual photosynthetic activities of temperate evergreen and deciduous broadleaf tree species with simultaneous and successive leaf emergence in response to altitudinal air temperature
Authors: Fujita N. , Noma N. , Shirakawa H. , Kikuzawa K.
Published: September 2012

To explain why the composition of evergreen and deciduous forests changes along air temperature gradients, we measured several traits of single leaves from temperate deciduous and evergreen broadleaf trees with simultaneous and successive leaf emergence growing at different altitudes in the field. The parameters included seasonal net photosynthetic rate, longevity, mass per area, nitrogen content, and photosynthetic nitrogen‐use efficiency. With decreasing altitude, the leaf longevity of deciduous broadleaf trees increased, whereas the maximum net photosynthetic rate decreased. In contrast, leaf longevity of evergreen broadleaf trees decreased, whereas the minimum net photosynthetic rate in winter increased. Along the air temperature gradient, the annual production of deciduous trees with simultaneous leaf emergence may be constant, because the integrated lifetime net photosynthetic rate (ILNPR) of a single leaf changed little. In comparison, deciduous trees with successive leaf emergence may show enhanced annual production with increasing air temperature, by increasing the total leaf number per branch and tree under an extended growing season. Temperate evergreen broadleaf tree species may also show increased annual production with increasing air temperature by sufficiently raising the number of the first‐year leaves to the total leaves of branch and tree, which is accelerated by raising the integrated first‐year net photosynthetic rate of the single leaf, despite little change in the ILNPR. With increasing air temperature from cool‐temperate to warm‐temperate zones, evergreen broadleaf tree species gain an advantage of the annual production over deciduous broadleaf tree species with simultaneous leaf emergence.
Decreased Plasma Cholesterol Concentrations After PUFA‐Rich Diets are not Due to Reduced Cholesterol Absorption/Synthesis
Authors: Ramprasath Vanu R. , Jones Peter J. H. , Buckley Donna D. , Woollett Laura A. , Heubi James E.
Published: September 2012

Plasma cholesterol concentrations increase with consumption of high saturated fatty acid (SFA) and decrease with high polyunsaturated fatty acid (PUFA) diets, leading to shifts in lipid levels consistent with reduction in heart disease risk. Direct measurements of cholesterol absorption, one of the key regulators of plasma cholesterol levels, have not been performed in humans after consumption of high PUFA diets. Thus, cholesterol absorption and fractional synthesis rates (FSRs) were measured in 16 healthy adults (8 males and 9 females) using a randomized cross‐over study with a diet containing high (PUFA/SFA) P/S ratio (2:1) and a low P/S ratio (0.5:1). Cholesterol absorption and fractional cholesterol synthetic rates were measured using stable isotopes after 20 days of dietary intervention. Diet did not affect cholesterol absorption or synthesis. There was a significant decrease in plasma cholesterol concentrations (P < 0.02), specifically LDL‐cholesterol (P < 0.02), without a change in HDL‐cholesterol or triacylglycerol concentrations. Intraluminal cholesterol solubilization and plasma sterol (cholesterol biosynthetic intermediates and plant sterols) levels were not affected by diet. Thus, consumption of diets with a high P/S ratio reduces plasma total and LDL‐cholesterol concentrations independent of shifts in cholesterol absorption or synthesis.
Das Deutsche Netzwerk für mitochondriale Erkrankungen (mitoNET)
Authors: Büchner B. , Gallenmüller C. , Lautenschläger R. , Kuhn K. , Wittig I. , Schöls L. , Rapaport D. , Seelow D. , Freisinger P. , Prokisch H. , Sperl W. , Wenz T. , Behl C. , Deschauer M. , Kornblum C. , Schneiderat P. , Abicht A. , Schuelke M. , Meitinger T. , Klopstock T.
Published: September 2012

Das mitoNET wurde als interdisziplinäres, deutschlandweites Netzwerk mit dem Ziel konzipiert, eine Verbesserung der Patientenversorgung auf dem Gebiet der mitochondrialen Erkrankungen zu erreichen. Das horizontale klinische Netzwerk des mitoNET umfasst 8 neurologische und 13 pädiatrische Kliniken, die für die Patientenrekrutierung, deren Phänotypisierung und die Erfassung des natürlichen Verlaufs im Rahmen von jährlichen Kontrolluntersuchungen zuständig sind. Die Speicherung der erhobenen Daten erfolgt in einer eigens entwickelten webbasierten Registerdatenbank. Das Netzwerk betreibt 2 Biobanken zur Asservierung von DNA, RNA, Plasma sowie von diagnostisch gewonnenen Fibro- und Myoblasten. Vier Forschungsprojekte zielen auf eine Verbesserung des diagnostischen Spektrums durch Etablierung neuer Methoden, und ein Teilprojekt beschäftigt sich mit der Überprüfung neuer Therapiemöglichkeiten. Das mitoNET wird seit Anfang 2009 vom Bundesministerium für Bildung und Forschung (BMBF, Förderkennzeichen 01GM1113A) gefördert.
Trace Fossil Assemblages in Mixed Siliciclastic-Carbonate Sediments of the Kaladongar Formation (Middle Jurassic), Patcham Island, Kachchh, Western India
Authors: Joseph Jaquilin K. , Patel Satish J. , Bhatt Nishith Y.
Published: September 2012

The Middle Jurassic rocks of the Kaladongar Formation well exposed in the Kaladongar Hill range of the Patcham Island and Kuar Bet of the Northern Kachchh comprises of ∼450 m thick sequence of mixed siliciclastic-carbonate sediments intercalated with shales. These Mixed siliciclastic-carbonate sediments show wide variation in textural and mineralogical composition and represent genetically related six rock types: micritic sandstone, allochemic sandstone, sandy allochemic limestone, micrtic mudrock, sandy micrite and muddy micrite; which are highly bioturbated and show behaviourally diverse groups of trace fossils. Total 34 ichnogenera are identified, which includes, Arenicolites, Asterosoma, Beaconites, Bergaueria, Chondrites, Cochlichnus, Dactylophycus, Daedalus, Didymaulichnus, Diplocraterion, Gordia, Gyrochorte, Gyrolithes, Ichnocumulus, Laevicyclus, Lockeia, Margaritichnus, Monocraterion, Nereites, Ophiomorpha, Palaeophycus, Phoebichnus, Phycodes, Pilichnus, Planolites, Plug Shaped Form, Protovirgularia, Rhizocorallium, Scolicia, Skolithos, Taenidium, Teichichnus, Thalassinoides and Walcottia. These trace fossils are classified into six morphological groups namely, circular and elliptical structures; simple structures; branched structures; rosette structures; spreiten structures; and winding and meandering structures. These trace fossils are further group into eight assemblages which occurred together into mixed siliciclastic-carbonate sediments, include, Asterosoma assemblage, Gyrochorte assemblage, Rhizocorallium assemblage, Thalassinoides assemblage, Planolites-Palaeophycus assemblage, Phycodes assemblage, Ophiomorpha assemblage and Skolithos assemblage. The recurring pattern of these assemblages through the sequence displays the development of Skolithos and Cruziana ichnofacies and at places the mixed Skolithos-Cruziana ichnofacies which suggest a low wave and current energy conditions with intervening period of high wave and current energy conditions and an intermediate period of stressful environments, respectively. Sedimentological and ichnological data suggest that the deposition of the mixed siliciclastic-carbonate sediments of the Kaladongar Formation took place in the foreshore to offshore environment under fluctuating wave and current energy condition.
Late Cretaceous Tectonic Change of the Eastern Margin of the Tibetan Plateau – Results from Multisystem Thermochronology
Authors: Deng Bin , Liu Shugen , Li Zhiwu , Cao Junxing , Sun Wei
Published: September 2012

Partially due to lack of structural and sedimentary records to constrain the Jurassic-to-Cretaceous evolution, there was a missing process here in the eastern margin of Tibetan Plateau as it changed from the Paleo-Tethyan to Neo-Tethyan regime. Based on the analysis of 125 thermochronology ages (U/Pb, 40Ar/39A, 87Rb/86Sr, FT, U-Th/He) of igneous rocks from the eastern margin of Tibet, we propose a multisystem thermochronology approach to restore the cooling and emplacement of granites and decipher the missing process. Our integrated study suggests that a key Late Cretaceous (about 100Ma) tectonic change from the Paleo-Tethyan to Neo-Tethyan regime took place there. In the Late Triassic period, the initial emplacement of granite in the Songpan-Ganzi Fold Belt (SGFB) was characterized by a decrease in emplacement age and depth from west to east, and from north to south. Subsequently, all were followed by a very long period of slow cooling, which was followed by a rapid emplacement of about 100Ma. The intensive granite emplacement took place all over except northeastern SGFB, with a decrease in emplacement depth from west to east, which was linked with the far-field effect of Lhasa-Qiangtang collision. After this episode, the cooling history of granite in SGFB had a rapid emplacement on the subsurface under the control of the Neo-Tethyan regime. This process has control of the post Late Cretaceous regional magmatic activity and tectonics, as well as the sedimentary response in Sichuan and Xichang basin.
Experimental Evaluation of Solubility of Gypsum
Authors: Behnamtalab Ehsan
Published: September 2012

Karstic rocks exist in different areas of the world having by case useful/ harmful structural and environmental impacts. These rocks like gypsum and salt are dissolved against water.

In the current research, gypsum solubility is investigated by collecting outcomes of several experiments on crushed gypsums. During the tests, rates of gypsum solubility were measured and appraised through application of various parameters such as compaction quantity, period of water flow inside specimen as well as diameter of the initial trial hole increase.

The initial trial holes’ diameters were 0 (in the specimen without hole), 5, 8, 10 and 12 millimeters. Two compaction cases were comprised; with and without compaction. Furthermore it should be mentioned that flow of water was continued inside the specimens for a period of 3, 10, 20 and 30 days in the separate experiments in order to assess the time factor on the solubility quantity of the gypsum. Solution rate respectively for crushed gypsum were computed 2.49 cm/year. These experiments indicate that progress of solution phenomena does not have a particular trend.
Geochemistry and Petrogenesis of Anorogenic(?) Granitoids of West Garo Hills, Meghalaya
Authors: Choudhury D. K. , Pradhan A. K. , Zakaulla S. , Umamaheswar K.
Published: September 2012

The granite in Samingiri - Dilsekgiri area occurs as discordant, isolated pluton within the migmatitic terrain of West Garo Hills district, Meghalaya. The pluton is exposed over 140 sq km (18 km x 8 km). It exhibits structures of solid state and piecemeal stoping effect proximal to the contact and enveloped by a contact metamorphic aureole of albite-epidote-hornfels facies. Modally, it is biotite-monzogranite and biotite-syenogranite with minor biotite, chlorite, epidote and sericite and accessories like zircon, apatite, allanite, pyrite, magnetite and sphene. Geochemically, it is marked by restricted composition (69-76 wt% SiO2), high alkalies, low Ca, metaluminous to strongly peraluminous (Molar Al2O3/CaO+Na2O+K2O = 0.95 - 1.54), high FeO/MgO, high Ga/Al, high contents of Rb, Sr, Ba, Y, Zr and Ce and depleted in Ti and P. The field observation, mineralogical and geochemical aspects indicate the post-tectonic nature of West Garo pluton more like as A-type granite formed by partial melting of lower crustal blocks followed by low to moderate degree of fractional differentiation. Low Ca, alkaline nature and peraluminous character point to A-type nature of West Garo granite significantly different from other granites of Meghalaya Plateau. Rb-Sr age (616±86 Ma) of granite, however, corresponds to widespread Middle to Upper Pan African activity, a thermal event prevailed during Late Proterozoic - Early Palaeozoic (500-800 Ma) period, manifested in the form of several granitic intrusions in the basement gneissic complex and the overlying Proterozoic metasediments of the Shillong Group in Meghalaya Plateau.
Population Trends as a Counterweight to Central City Decline, 1950–2000
Authors: Boustan Leah , Shertzer Allison
Published: September 2012

The share of metropolitan residents living in central cities declined dramatically from 1950 to 2000. We argue that cities would have lost even further ground if not for demographic trends such as renewed immigration, delayed childbearing, and a decline in the share of households headed by veterans. We provide causal estimates of the effect of children on residential location using the birth of twins. The effect of veteran status is identified from a discontinuity in the probability of military service during and after the mass mobilization for World War II. Our results suggest that these changes in demographic composition were strong enough to bolster city population but not to fully counteract socioeconomic factors favoring suburban growth.
G/A polymorphism in intronic sequence affects the processing of MAO‐B gene in patients with Parkinson disease
Authors: Jakubauskiene Egle , Janaviciute Valda , Peciuliene Inga , Söderkvist Peter , Kanopka Arvydas
Published: September 2012

Monoamine oxidase B (MAO‐B) plays an important role in the metabolism of neuroactive and vasoactive amines in the central nervous system and peripheral tissues. Increased levels of MAO‐B mRNA and enzymatic activity have been reported in platelets from patients with Parkinson's and Alzheimer's diseases, however the triggers of enhanced mRNA levels are unknown. Our results demonstrate for the first time that G/A dimorphism in intron 13 sequence creates splicing enhancer thus stimulating intron 13 removal efficiency. The increased MAO‐B protein levels might serve as a surrogate marker for – Parkinson disease.
Dietary patterns on weekdays and weekend days in 4–14-year-old Danish children
Authors: Rothausen Berit W. , Matthiessen Jeppe , Andersen Lene F. , Brockhoff Per B. , Tetens Inge
Published: September 2012

Little is known about dietary patterns on weekdays and weekend days in children, and the aim of the present study was to investigate 4–14-year-old children's dietary patterns specifically on weekdays (Monday–Thursday) and weekend days (Saturday–Sunday). Dietary data were derived from the Danish National Survey of Dietary Habits and Physical Activity 2003–8, where a total of 784 children aged 4–14 years completed a 7 d pre-coded food record. Principal component analysis was used to identify dietary patterns in the age groups 4–6, 7–10 and 11–14 years. Consistently, two dietary patterns, labelled ‘processed’ and ‘health conscious’, emerged on both weekdays and weekend days. Factor scores from corresponding dietary patterns were significantly correlated between weekdays and weekend days with the exception of the ‘health conscious’ pattern in the 7–10-year-olds. Within each age group, children with high agreement for the ‘processed’ pattern had a significantly higher dietary energy density, which was reflected in significantly higher intakes of sugar-sweetened beverages and lower intakes of fruit and vegetables, compared with children with high agreement for the ‘health conscious’ pattern (P< 0·05). Moreover, these variables indicated less healthy dietary intakes on weekend days than on weekdays for both patterns. In conclusion, two distinct dietary patterns, labelled ‘processed’ and ‘health conscious’, were identified on both weekdays and weekend days for each age group. While overall major dietary patterns may somewhat track between weekdays and weekends, the specific foods actually eaten became less healthy during weekends.
FAIRNESS OF UTILIZING HEALTH CARE FACILITIES AND OUT-OF-POCKET PAYMENT BURDEN: EVIDENCE FROM CAMBODIA
Authors: DALAL KOUSTUV , AREMU OLATUNDE
Published: September 2012

Catastrophic spending on health care through out-of-pocket payment is a huge problem in most low- and middle-income countries all over the world. The collapse of health systems and poverty have resulted in the proliferation of the private health sector in Cambodia, but very few studies have examined the fairness in ease of utilization of these services based on mode of payment. This study examined the utilization of health services for sickness or injury and identified its relationship with people's ability to pay for treatment seeking at various instances. Based on cross-sectional data from the Cambodian 2007 Demographic and Health Survey, the economic index estimated through principal component analysis and Lorenz curve was used to quantify the degree of fairness and equality in utilization and payment burden among the respondents. A distinct level of fairness was found in health care utilization and out-of-pocket payments. Specifically, use of private health care facilities and over-the-counter remedies dominate, and out-of-pocket payments cut across all socioeconomic strata. As many countries in low- and middle-income regions, and most importantly those in transition such as Cambodia, are repositioning their health systems, efforts should be made towards maintaining equitable access through adoption of finance mechanisms that make utilization of health care services fair and equitable.
When working is not enough: food insecurity in the Canadian labour force
Authors: McIntyre Lynn , Bartoo Aaron C , Emery JC Herbert
Published: September 2012

Objective

Food insecurity, lack of access to food due to financial constraints, is highly associated with poor health outcomes. Households dependent on social assistance are at increased risk of experiencing food insecurity, but food insecurity has also been reported in households reporting their main source of income from employment/wages (working households). The objective of the present study was to examine the correlates of food insecurity among households reliant on employment income.

Design

Working households reporting food insecurity were studied through analysis of the Canadian Community Health Survey, 2007–2008, employing descriptive statistics and logistic regression. Food insecurity was measured using the Household Food Security Survey Module; all provinces participated.

Setting

Canada.

Subjects

Canadian households where main income was derived through labour force participation. Social assistance recipients were excluded.

Results

For the period 2007–2008, 4 % of working households reported food insecurity. Canadian households reliant on primary earners with less education and lower incomes were significantly more likely to experience food insecurity; these differences were accentuated across some industry sectors. Residence in Quebec was protective. Working households experiencing food insecurity were more likely to include earners reporting multiples jobs and higher job stress. Visible minority workers with comparable education levels experienced higher rates of food insecurity than European-origin workers.

Conclusions

Reliance on employment income does not eliminate food insecurity for a significant proportion of households, and disproportionately so for households with racialized minority workers. Increases in work stress may increase the susceptibility to poor health outcomes of workers residing in households reporting food insecurity.
Radiation belt probes launched
Authors: Showstack Randy
Published: September 2012

Storms on Earth delayed by only a few days the launch of NASA's Radiation Belt Storm Probes (RBSP), which blasted off on 30 August for a 2‐year tour to explore the Van Allen radiation belts. The two satellites will help scientists learn about the processes that affect electrons and ions in the donut‐shaped belts and how the belts change in the context of geomagnetic storms. “The information collected from these probes will benefit the public by allowing us to better protect our satellites and understand how space weather affects communications and technology on Earth,” said John Grunsfeld, associate administrator for NASA's Science Mission Directorate. Each probe carries an identical suite of instruments, including an Energetic Particle, Composition, and Thermal Plasma Suite; Electric and Magnetic Field Instrument Suite and Integrated Science; Electric Field and Waves Suite; Radiation Belt Storm Probes Ion Composition Experiment; and Relativistic Proton Spectrometer. RBSP is part of NASA's Living With a Star program and is managed for NASA by the Johns Hopkins University's Applied Physics Laboratory. For more information, see http://rbsp.jhuapl.edu.
A new type of climate network based on probabilistic graphical models: Results of boreal winter versus summer
Authors: Ebert‐Uphoff Imme , Deng Yi
Published: September 2012

In this paper we introduce a new type of climate network based on temporal probabilistic graphical models. This new method is able to distinguish between direct and indirectconnections and thus can eliminate indirect connections in the network. Furthermore, while correlation‐based climate networks focus onsimilarity between nodes, this new method provides an alternative viewpoint by focusing on information flowwithin the network over time. We build a prototype of this new network utilizing daily values of 500 mb geopotential height over the entire globe during the period 1948 to 2011. The basic network features are presented and compared between boreal winter and summer in terms of intra‐location properties that measurelocal memoryat a grid point and inter‐location properties that quantifyremote impactof a grid point. Results suggest that synoptic‐scale, sub‐weekly disturbances act as the main information carrier in this network and their intrinsic timescale limits the extent to which a grid point can influence its nearby locations. The frequent passage of these disturbances over storm track regions also uniquely determines the timescale of height fluctuations thuslocal memoryat a grid point. The poleward retreat of synoptic‐scale disturbances in boreal summer is largely responsible for a corresponding poleward shift of local maxima inlocal memory and remote impact, which is most evident in the North Pacific sector. For the NH as a whole, both local memory and remote impactstrengthen from winter to summer leading to intensified information flow and more tightly‐coupled network nodes during the latter period.
Is sea level rise accelerating in the Chesapeake Bay? A demonstration of a novel new approach for analyzing sea level data
Authors: Ezer Tal , Corlett William Bryce
Published: September 2012

Sea level data from the Chesapeake Bay are used to test a novel new analysis method for studies of sea level rise (SLR). The method, based on Empirical Mode Decomposition and Hilbert‐Huang Transformation, separates the sea level trend from other oscillating modes and reveals how the mean sea level changes over time. Bootstrap calculations test the robustness of the method and provide confidence levels. The analysis shows that rates of SLR have increased from ∼1–3 mm y−1 in the 1930s to ∼4–10 mm y−1 in 2011, an acceleration of ∼0.05–0.10 mm y−2 that is larger than most previous studies, but comparable to recent findings by Sallenger and collaborators. While land subsidence increases SLR rates in the bay relative to global SLR, the acceleration results support Sallenger et al.'s proposition that an additional contribution to SLR from climatic changes in ocean circulation is affecting the region.
The influence of hemispheric asymmetries on field‐aligned ion drifts at the geomagnetic equator
Authors: Burrell A. G. , Heelis R. A.
Published: September 2012

In the topside ionosphere, equatorial field‐aligned ion drifts are driven by field‐aligned gradients in the plasma pressure. These gradients form due to hemispheric asymmetries in plasma temperature and density, which are caused by the sun and the neutral atmosphere. The role of the neutral atmosphere in creating a field‐aligned plasma pressure gradient and driving ion drifts across the geomagnetic equator is examined for several local times during solar minimum. Using satellite observations and complimentary modeled data, the field‐aligned ion drifts are found to correlate with the vertical displacement between conjugate ion density peaks in both the observed and modeled data sets. In the modeled data sets, an even stronger correlation is seen between the field‐aligned ion drift and the total neutral wind along the magnetic meridian at the height of the ion density peak. This correlation is seen to improve in the absence of anE × B drift.
Thermospheric basis functions for improved dynamic calibration of semi‐empirical models
Authors: Sutton Eric K. , Cable Samuel B. , Lin Chin S. , Qian Liying , Weimer Daniel R.
Published: September 2012

State‐of‐the‐art satellite drag models require upgrades to meet operational Precision Orbit Determination requirements for collision avoidance, reentry predictions and catalog maintenance. However, accurate model representations of thermospheric density are not currently possible without the use of data assimilation, or model calibration. Furthermore, due to sparse data sampling in the thermosphere, such calibration has only been successfully demonstrated by fitting the available data to a low‐dimensional model. The High Accuracy Satellite Drag Model (HASDM), used operationally by the Space Surveillance Network to aid in the tracking of low‐earth orbiting satellites, compensates for errors in the Jacchia‐70 static diffusion model by fitting a truncated set of spherical harmonics to a subset of recent satellite tracking data. We present a technique to derive a set of basis functions better suited to capturing the spatial variability and response of the thermosphere. By comparing the uncompensated Jacchia‐70 model with the Thermosphere‐Ionosphere‐Electrodynamic General Circulation Model (TIEGCM), we create a new set of orthogonal basis functions that can be used to calibrate semi‐empirical models such as HASDM with increased accuracy in the presence of sparse data. An initial analysis of the new approach, driven by synthetic data, shows a 32.9% improvement in the RMS error over the current implementation of HASDM.
Computing many-body wave functions with guaranteed precision: The first-order Møller-Plesset wave function for the ground state of helium atom
Authors: Bischoff Florian A. , Harrison Robert J. , Valeev Edward F.
Published: September 2012

We present an approach to compute accurate correlation energies for atoms and molecules using an adaptive discontinuous spectral-element multiresolution representation for the two-electron wave function. Because of the exponential storage complexity of the spectral-element representation with the number of dimensions, a brute-force computation of two-electron (six-dimensional) wave functions with high precision was not practical. To overcome the key storage bottlenecks we utilized (1) a low-rank tensor approximation (specifically, the singular value decomposition) to compress the wave function, and (2) explicitly correlated R12-type terms in the wave function to regularize the Coulomb electron-electron singularities of the Hamiltonian. All operations necessary to solve the Schrödinger equation were expressed so that the reconstruction of the full-rank form of the wave function is never necessary. Numerical performance of the method was highlighted by computing the first-order Møller-Plesset wave function of a helium atom. The computed second-order Møller-Plesset energy is precise to ∼2 microhartrees, which is at the precision limit of the existing general atomic-orbital-based approaches. Our approach does not assume special geometric symmetries, hence application to molecules is straightforward.
Interaction of an ultrashort optical pulse with a metallic nanotip: A Green dyadic approach
Authors: Arbouet Arnaud , Houdellier Florent , Marty Renaud , Girard Christian
Published: September 2012

We consider the interaction of an ultrashort optical pulse with a metallic nanotip. In the framework of the Green dyadic method, we calculate the time-dependent electric field in the vicinity of the metallic nano-object. The electric field enhancement at the tip apex, its temporal evolution, and its dependence upon the polarization of the incident electric field are addressed. By comparing the case of tungsten and gold nanotips, we show that significantly larger electric field enhancements can be obtained with the latter and point out different temporal responses. Our description provides the time-dependent spatial distribution of the electric field around metallic nano-objects of arbitrary geometries which is the first step to describe light-matter interaction in recently developed laser-driven femtosecond electron nanosources or recent results in ultrafast nanoplasmonics.
Symplectic cohomologies on phase space
Authors: Tsai Chung-Jun , Tseng Li-Sheng , Yau Shing-Tung
Published: September 2012

The phase space of a particle or a mechanical system contains an intrinsic symplectic structure, and hence, it is a symplectic manifold. Recently, new invariants for symplectic manifolds in terms of cohomologies of differential forms have been introduced by Tseng and Yau. Here, we discuss the physical motivation behind the new symplectic invariants and analyze these invariants for phase space, i.e., the non-compact cotangent bundle.
Cold collisions of polyatomic molecular radicals with S-state atoms in a magnetic field: An ab initio study of He + ${\rm CH}_2(\tilde{X})$ CH 2(X̃) collisions
Authors: Tscherbul T. V. , Grinev T. A. , Yu H.-G. , Dalgarno A. , Kłos Jacek , Ma Lifang , Alexander Millard H.
Published: September 2012

We develop a rigorous quantum mechanical theory for collisions of polyatomic molecular radicals with S-state atoms in the presence of an external magnetic field. The theory is based on a fully uncoupled space-fixed basis set representation of the multichannel scattering wave function. Explicit expressions are presented for the matrix elements of the scattering Hamiltonian for spin-1/2 and spin-1 polyatomic molecular radicals interacting with structureless targets. The theory is applied to calculate the cross sections and thermal rate constants for spin relaxation in low-temperature collisions of the prototypical organic molecule methylene [\documentclass[12pt]{minimal}\begin{document}${\rm CH}_2(\tilde{X}^3B_1)$\end{document} CH 2(X̃3B1)] with He atoms. To this end, two accurate three-dimensional potential energy surfaces (PESs) of the He–\documentclass[12pt]{minimal}\begin{document}${\rm CH}_2(\tilde{X}^3B_1)$\end{document} CH 2(X̃3B1) complex are developed using the state-of-the-art coupled-cluster method including single and double excitations along with a perturbative correction for triple excitations and large basis sets. Both PESs exhibit shallow minima and are weakly anisotropic. Our calculations show that spin relaxation in collisions of CH2, CHD, and CD2 molecules with He atoms occurs at a much slower rate than elastic scattering over a large range of temperatures (1 μK–1 K) and magnetic fields (0.01–1 T), suggesting excellent prospects for cryogenic helium buffer-gas cooling of ground-state ortho-\documentclass[12pt]{minimal}\begin{document}${\rm CH}_2(\tilde{X}^3B_1)$\end{document} CH 2(X̃3B1) molecules in a magnetic trap. Furthermore, we find that ortho-CH2 undergoes collision-induced spin relaxation much more slowly than para-CH2, which indicates that magnetic trapping can be used to separate nuclear spin isomers of open-shell polyatomic molecules.
High temperature phase transformation studies in magnetite nanoparticles doped with Co2+ ion
Authors: Pati S. S. , Gopinath S. , Panneerselvam G. , Antony M. P. , Philip John
Published: September 2012

We investigate the effect of Co2+ ion doping in magnetite (Fe3O4) on its crystal structure, magnetic properties, and phase stability during air and vacuum annealing. The nanoparticles are prepared by co-precipitation method and the particles are characterized by XRD, small angle x-ray scattering (SAXS), themogravimetric and differential scanning calorimetry (DSC), and vibrating sample magnetometer. The SAXS analysis on the doped samples show the most probable size, shape, and the polydispersity of particles, synthesized with different fractions (0–0.6) of Co2+ ion doping remains almost the same. On increasing cobalt content ferrimagnetic to the antiferromagnetic hematite (α-Fe2O3) phase transformation temperature is found to increase dramatically. For 0.1 fraction of Co2+ metal ion doping, an enhancement of 100 °C in the γ-Fe2O3 to α-Fe2O3 phase transition temperature is observed in the air annealed samples, whereas magnetic nature remains stable up to 1000 °C in vacuum annealed samples. On increasing the cobalt fractions beyond 0.2, air annealed samples show no change in the phase transition temperature. The observed enhancement in the phase transition temperature is attributed to the increased activation energy for phase transformation in presence of Co2+. Further, the DSC results corroborate the finding of an increase in the maghemite to hematite phase transition temperature with increase in cobalt fraction (x). The decrease in enthalpy from 89.86 to 17.62 J g−1 with an increase in cobalt content indicates that the degree of conversion of maghemite to hematite decreases with the cobalt content, which is in good agreement with the Rietveld analysis. The decrease in the Ms value in air annealed sample is attributed to the re-distribution of cations in the tetrahedral and octahedral sites, as the Fe3+A-Fe3+B super-exchange interaction is different from the Co2+A-Fe3+B interaction. These results suggest that a very small percentage of Co2+ metal ion doping can dramatically enhance the thermal stability of magnetic nanoparticles, which will have important consequences on the phase stability of ferrite nanocrystals.
Simulating self-avoiding walks in bounded domains
Authors: Kennedy Tom
Published: September 2012

Let D be a domain in the plane containing the origin. We are interested in the ensemble of self-avoiding walks (SAWs) in D which start at the origin and end on the boundary of the domain. We introduce an ensemble of SAWs that we expect to have the same scaling limit. The advantage of our ensemble is that it can be simulated using the pivot algorithm. Our ensemble makes it possible to accurately study Schramm-Loewner evolution (SLE) predictions for the SAW in bounded simply connected domains. One such prediction is the distribution along the boundary of the endpoint of the SAW. We use the pivot algorithm to simulate our ensemble and study this density. In particular the lattice effects in this density that persist in the scaling limit are seen to be given by a purely local function.
Nonlinear nonclassical acoustic method for detecting the location of cracks
Authors: Quan Li , Liu XiaoZhou , Gong XiuFen
Published: September 2012

In this study, a new nonlinear acoustic method that makes full use of the sensitivity of higher harmonics caused by internal microcracks is proposed to locate multiple cracks in a one-dimensional bar. The tested bar was coupled with an acoustic emitter, the frequency used by the transducer is the eigenfrequency of the bar, and the boundary of the emitter can be treated as free. A mass load was added to the other end of the bar to provide an asymmetrical boundary condition. The receiver was scanned along the propagation direction of acoustic wave. The relationships between the amplitude, the phase of the harmonics, and the positions of the cracks can be used to locate multiple cracks in the bar. The higher harmonic frequencies induced due to crack nonlinearity are different from the eigenfrequencies of the bar. This creates an amplitude difference in the vibration on each side of the cracks and can be used to locate multiple cracks in a one-dimensional bar. Numerical calculations were carried out to verify the method and possible approaches to improve the accuracy of this method are discussed.
Magnetic force microscopy sensors providing in-plane and perpendicular sensitivity
Authors: Mühl T. , Körner J. , Philippi S. , Reiche C. F. , Leonhardt A. , Büchner B.
Published: September 2012

We present a bimodal magnetic force microscopy sensor consisting of a conventional cantilever beam, a spacer element, and an iron-filled carbon nanotube. Depending on the mode of the cantilever's resonant flexural vibration, the sensor is sensitive to magnetic field derivatives parallel and perpendicular to the sample's surface. This multifunctionality is supported by the scalar-type behavior of the magnetic monopole-like end of the iron-filled carbon nanotube.
Thermally induced interface chemistry in Mo/B4C/Si/B4C multilayered films
Authors: Nyabero S. L. , van de Kruijs R. W. E. , Yakshin A. E. , Zoethout E. , Bijkerk F.
Published: September 2012

B4C diffusion barrier layers are often introduced into Mo/Si multilayered films for enhancement of thermal stability. We observe that such multilayered films exhibit both period expansion and period compaction upon annealing at temperatures below 300 °C, depending on the annealing temperature and time. Using in-situ grazing incidence x-ray reflection measurements during sequential annealing, we resolved picometer periodicity changes in Mo/B4C/Si/B4C, Si/B4C, and Mo/B4C multilayer films, and show that the two opposite period-change effects are a result of interaction of Si with B4C layers, leading to expansion, and MoxSiy formation, leading to compaction. The study of Si/B and Si/C multilayer sub-systems suggests that the cause of expansion is the formation of relatively low density SixBy compounds at the Si-B4C interface. Although the Mo-B4C interface seems to be stable based on reflectometry data, other techniques such as depth profiling x-ray photoelectron spectroscopy and wide angle x-ray diffraction measurements show that Mo and B4C actually intermix.
Digital magnetic heterostructures based on GaN using GGA-1/2 approach
Authors: Santos J. P. T. , Marques M. , Ferreira L. G. , Pelá R. R. , Teles L. K.
Published: September 2012

We present ab-initio calculations of seven digital magnetic heterostructures, GaN δ-doped with V, Cr, Mn, Fe, Co, Ni, and Cu, forming two-dimensional systems. Only GaN δ-doped with V or Cr present a ferromagnetic ground state with high Curie temperatures. For both, to better describe the electronic properties, we used the GGA-1/2 approach. The ground state of GaN/Cr resulted in a two dimensional half-metal, with 100% spin polarization. For GaN/V, we obtained an insulating state: integer magnetic moment of 2.0 μB, a minority spin gap of 3.0 eV close to the gap of GaN, but a majority spin gap of 0.34 eV.
Size dependent Cu dielectric function for plasmon spectroscopy: Characterization of colloidal suspension generated by fs laser ablation
Authors: Santillán J. M. J. , Videla F. A. , Fernández van Raap M. B. , Schinca D. C. , Scaffardi L. B.
Published: September 2012

Copper metal nanoparticles (Nps) have received increasing interest during the last years due to their potential applications in several fields of science and technology. Their optical properties depend on the characteristics of the dielectric function of the metal, their size, and the type of environment. The contribution of free and bound electrons on the dielectric function of copper Nps is analyzed as well as their influence on its plasmonic properties. The contribution of free electrons is corrected for particle size under 10 nm, introducing a term inversely proportional to the particle's radius in the damping constant. For bound electron contribution, interband transitions from the d-band to the conduction band are considered. For particles with sizes below 2 nm, the larger spacing between electronic energy levels must be taken into account by making the electronic density of states in the conduction band size-dependent. Considering these specific modifications, optical parameters and band energy values could be determined by fitting the bulk complex dielectric function. The obtained values were coefficient for bound electron contribution Kbulk = 2 × 1024, gap energy Eg = 1.95 eV, Fermi energy EF = 2.15 eV, and bound electrons damping constant γb = 1.15 × 1014 Hz. Based on the dielectric function determined in this way, experimental extinction spectra of colloid suspensions generated by ultrafast laser ablation of a solid copper target in liquids was fitted using the Drude-interband model and Mie's theory. Depending on the experimental conditions and liquid medium, the particles in the suspension may have nanometric or subnanometric core size and may be capped with a shell of oxide. From the fitting, it was possible to determine the structure and size distribution of spherical bare core and core-shell copper Nps in the nanometer-subnanometer size range. These results were compared with those obtained by standard microscopy techniques such as AFM and HRTEM. There is a very good agreement between the three techniques, showing that optical extinction spectroscopy (OES) is a good complementary technique to standard high resolution electron microscopy and AFM for sizing spherical nanometric-subnanometric Nps. OES has also the advantage of a very good measurement statistics, due to the large number of probed particles across the sample cell. Besides, it avoids coalescence effects since the measurement is made directly on the colloidal suspension.
P-type ZnO thin films achieved by N+ ion implantation through dynamic annealing process
Authors: Myers M. A. , Myers M. T. , General M. J. , Lee J. H. , Shao L. , Wang H.
Published: September 2012

ZnO thin films were grown on sapphire (0001) substrates by pulsed-laser deposition at 700 °C. 70 keV N+ ion implantation was performed under various temperatures and fluences in the range of 300−460 °C and 3.0×1014−1.2×1015 cm−2, respectively. Hall measurements indicate that the ZnO films implanted at 460 °C are p-type for all fluences used herein. Hole-carrier concentrations lie in the range of 2.4×1016−5.2×1017 cm−3, hole mobilities in the range of 0.7−3.7 cm2 V−1 s−1, and resistivities between 18−71 Ωcm. Transmission-electron microscopy reveals major microstructural differences between the n-type and p-type films. Ion implantation at elevated temperatures is shown to be an effective method to introduce increased concentrations of p-type N dopants while reducing the amount of stable post-implantation disorder.
Two-dimensional double layer in plasma in a diverging magnetic field
Authors: Saha S. K. , Raychaudhuri S. , Chowdhury S. , Janaki M. S. , Hui A. K.
Published: September 2012

Plasma created by an inductive RF discharge is allowed to expand along a diverging magnetic field. Measurement of the axial plasma potential profile reveals the formation of an electric double layer near the throat of the expansion chamber. An accelerated ion beam has been detected in the downstream region, confirming the presence of the double layer. The 2-D nature of the ion energy distribution function of the downstream plasma has been studied by a movable ion energy analyser, which shows that the beam radius increases along the axial distance. The 2-D structure of the plasma potential has been studied by a movable emissive probe. The existence of a secondary lobe in the contour plot of plasma equipotential is a new observation. It is also an interesting observation that the most diverging magnetic field line not intercepting the junction of the discharge tube and the expansion chamber has an electric field aligned with it.
Correlating stress generation and sheet resistance in InAlN/GaN nanoribbon high electron mobility transistors
Authors: Jones Eric J. , Azize Mohamed , Smith Matthew J. , Palacios Tomás , Gradečak Silvija
Published: September 2012

We report the nanoscale characterization of the mechanical stress in InAlN/GaN nanoribbon-structured high electron mobility transistors (HEMTs) through the combined use of convergent beam electron diffraction (CBED) and elastic mechanical modeling. The splitting of higher order Laue zone lines in CBED patterns obtained along the [540] zone axis indicates the existence of a large strain gradient in the c-direction in both the planar and nanoribbon samples. Finite element models were used to confirm these observations and show that a passivating layer of Al2O3 can induce a tensile stress in the active HEMT layer whose magnitude is dependent on the oxide layer thickness, thus, providing important ramifications for device design and fabrication.
Influence of the side-Ohmic contact processing on the polarization Coulomb field scattering in AlGaN/AlN/GaN heterostructure field-effect transistors
Authors: Luan Chongbiao , Lin Zhaojun , Lv Yuanjie , Meng Lingguo , Yu Yingxia , Cao Zhifang , Chen Hong , Wang Zhanguo
Published: September 2012

Using the measured capacitance-voltage curves of Ni Schottky contacts with different areas and the current-voltage characteristics for the circular and rectangular AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) with the side-Ohmic contacts, it is found that the polarization Coulomb field scattering caused by the polarization charge density variation at the AlGaN/AlN/GaN interfaces is closely related to the Ohmic-contact processing, and the side-Ohmic contact processing greatly weakens the polarization Coulomb field scattering in the AlGaN/AlN/GaN HFETs.