bluuebunny/crossref_metadata_2025 huggingface dataset:
Injuries Related to Hiking with a Pack During National Outdoor Leadership School Courses: A Risk Factor Analysis
Authors: Hamonko Matthew T. , McIntosh Scott E. , Schimelpfenig Tod , Leemon Drew
Published: January 2011

Objectives

To determine if packweight, anthropometry, and individual characteristics are related to acute musculoskeletal and soft tissue injuries while wearing backpacks on wilderness expeditions.

Methods

This was a review of prospectively gathered data on participants and instructors enrolled in National Outdoor Leadership School Rocky Mountain hiking courses between March 2008 and October 2009. Packweight, height, body weight, age, and gender were collected. Individuals that suffered acute musculoskeletal and soft tissue injuries while hiking with a backpack were recorded and compared to individuals that did not suffer injuries. Logistic regression was used to determine which variables were significantly correlated with injuries. Odds ratios with associated confidence intervals and p-values are reported.

Results

One thousand two hundred and one individuals were included in the final analysis. Twenty-six individuals of this population suffered reportable musculoskeletal and soft tissue injuries while hiking with a pack. None of the factors examined (packweight, height, body weight, age, gender, or packweight to body weight ratio) were significant in predicting acute injury.

Conclusions

Based on our results, an individual's packweight, anthropometry, and individual characteristics neither increase nor decrease their risk of experiencing a musculoskeletal or soft tissue injury while hiking with a backpack. Other factors, including fitness, pretrip training, and footwear, should be examined to determine appropriate strategies to reduce significant musculoskeletal and soft tissue injuries on wilderness expeditions.
Ambulatory Recording of Physiological Variables During an Ascent of Mt Aconcagua
Authors: Wagner Dale R.
Published: January 2011

The aim of this descriptive case study was to use an ambulatory biosensor system to capture data in real time in a harsh environment and to obtain continuous physiological measurements during an ascent of Argentina's Mt Aconcagua, the highest point in the Western Hemisphere. Between the 5800-m-high camp and the 6962-m summit, a 41-year-old male with previous high-altitude mountaineering experience was measured for minute-by-minute heart rate (60–154 beats/min), respiration rate (2–42 breaths/min), skin temperature (11.7–36.1°C), and core temperature (36.9–38.7°C) (1240 min of data: 417 min rest/sleep; 643 min ascent; 180 min descent). All of the measured variables were significantly correlated with each other ( p < 0.01). There were incidences of “open leads” and “recovered data,” indicating the potential for some aberrant data; however, data exist for each minute of the 1240 minutes of collection, and the values are within the expected physiological ranges. This study demonstrates the potential application of telemetry to monitor physiological variables during high altitude mountaineering.
Risks and Management of Prolonged Suspension in an Alpine Harness
Authors: Mortimer Roger B.
Published: January 2011

Suspension trauma is a state of shock induced by passive hanging. Those who survive passive suspension are at risk for rhabdomyolysis. In a wilderness setting, one can see this in cases of persons suspended on rope by their harness. In a conscious person, leg movements work the venous pump to return blood to the central circulation. In the person passively hanging, blood pools in the legs leading to hypoperfusion of vital organs. In the experimental setting, passive hanging has led to unconsciousness in a matter of minutes. Based on a previous series of deaths on rope that included 7 after rescue, many authors have recommended nonstandard treatment for shock including keeping rescued patients upright or squatting for 30 minutes prior to laying them down. This recommendation assumes that sudden death is a risk from acute volume overload or exposure to waste products in the returning blood. This suggestion is not supported by the original series that demonstrated sudden deaths after rescue nor by modern understandings of physiology. Search and rescue teams and party members assisting a colleague suspended unconscious on rope should follow standard resuscitation measures to restore circulation to vital organs immediately.
Ideals of Herzog–Northcott type
Authors: O'Carroll Liam , Planas-Vilanova Francesc
Published: January 2011

This paper takes a new look at ideals generated by 2×2 minors of 2×3 matrices whose entries are powers of three elements not necessarily forming a regular sequence. A special case of this is the ideals determining monomial curves in three-dimensional space, which were studied by Herzog. In the broader context studied here, these ideals are identified as Northcott ideals in the sense of Vasconcelos, and so their liaison properties are displayed. It is shown that they are set-theoretically complete intersections, revisiting the work of Bresinsky and of Valla. Even when the three elements are taken to be variables in a polynomial ring in three variables over a field, this point of view gives a larger class of ideals than just the defining ideals of monomial curves. We then characterize when the ideals in this larger class are prime, we show that they are usually radical and, using the theory of multiplicities, we give upper bounds on the number of their minimal prime ideals, one of these primes being a uniquely determined prime ideal of definition of a monomial curve. Finally, we provide examples of characteristic-dependent minimal prime and primary structures for these ideals.
Metamorphism and diachronous cooling in a contractional orogen: the Strandja Massif, NW Turkey
Authors: SUNAL G. , SATIR M. , NATAL'IN B. A. , TOPUZ G. , VONDERSCHMIDT O.
Published: January 2011

The southern part of the Strandja Massif, northern Thrace, Turkey, comprises a basement of various gneisses, micaschists and rare amphibolite, and a cover of metaconglomerate and metasandstone, separated from each other by a pre-metamorphic unconformity. Metamorphic grade decreases from the epidote–amphibolite facies in the south to the albite–epidote–amphibolite/greenschist-facies transition in the north. Estimated P–T conditions are 485–530°C and 0.60–0.80 GPa in the epidote–amphibolite facies domain, and decrease towards the transitional domain between greenschist- and epidote–amphibolite facies. Rb–Sr muscovite ages range from 162.9 ± 1.6 Ma to 149.1 ± 2.1 Ma, and are significantly older (279–296 Ma) in the northernmost part of the study area. The Rb–Sr biotite ages decrease from 153.9 ± 1.5 Ma in the south to 134.4 ± 1.3 Ma in the north. These age values in conjunction with the attained temperatures suggest that the peak metamorphism occurred at around 160 Ma and cooling happened diachronously, and Rb–Sr muscovite ages were not reset during the metamorphism in the northernmost part. Structural features such as (i) consistent S-dipping foliation and SW to SE-plunging stretching lineation, (ii) top-to-the-N shear sense, and (iii) N-vergent ductile shear zones and brittle thrusts suggest a N-vergent compressional deformation coupled with exhumation. We tentatively ascribe this metamorphism and subsequent diachronous cooling to the northward propagation of a thrust slice. The compressional events in the Strandja Massif were most probably related to the coeval N-vergent subduction/collision system in the southerly lying Rhodope Massif.
Security as translation: threats, discourse, and the politics of localisation
Authors: STRITZEL HOLGER
Published: January 2011

This article aims at enhancing our understanding of how collective interpretations of threats, stabilised and temporarily fixed in names, travel across different local discourse communities. I contend that globally accepted names result from gradual cross-cultural processes of localisation. Specifically, I argue that the discursive dynamics of elusiveness, compatibility and adaptation suggest a framework of analysis for how collective interpretations or names travel.
Protons and ion acceleration from thick targets at 1010 W/cm2 laser pulse intensity
Authors: Torrisi L. , Caridi F. , Giuffrida L.
Published: January 2011

Proton ion acceleration via laser-generated plasma is investigated at relatively low laser pulse intensity, on the order of 1010 W/cm2. Time-of-flight technique is employed to measure the ion energy and the relative yield. An ion collector and an ion energy analyzer are used with this aim and to distinguish the number of charge states of the produced ions. The kinetic energy and the emission yield are measured through a consolidated theory, which assumes that the ion emission follows the Coulomb-Boltzmann-Shifted function. The proton stream is generated by thin and thick hydrogenated targets and it is dependent on the free electron states, which increase the laser absorption coefficient and the ion acceleration. The maximum proton energy, of about 200 eV, and the maximum proton amount can be obtained with thick metallic hydrogenated materials, such as the titanium hydrate TiH2.
Cracking the Dutch Early Music Movement: the Repercussions of the 1969 Notenkrakersactie
Authors: RUBINOFF KAILAN R.
Published: January 2011

The Notenkrakersactie of 17 November 1969 was a landmark event for Dutch musical life: a group of composers disrupted a concert of the Concertgebouw Orchestra, protesting against the orchestra's lack of contemporary music programming. Scholars have tended to interpret this protest as a watershed for the avant-garde, but historical performance – not just contemporary music – proved to be a significant beneficiary. Early Musicians, like New Musicians, had common political goals and appealed to the youth counterculture. Ensuing reforms to the federal arts subsidy system, state-funded music schools, and conservatories in the 1970s were also advantageous for the Dutch Early Music movement. During the welfare retrenchment of the 1980s and the subsidy restructuring of the 1990s, Early Music ensembles economized and had greater success with mainstream recording companies and audiences than new music groups. Nearly forty years after the Notenkrakersactie, traditional symphony orchestras have less influence on Dutch musical life, but recent cutbacks to arts subsidies threaten contemporary music and historical performance alike.
Orality and Rhetoric in Scelsi's Music
Authors: DICKSON IAN
Published: January 2011

In his later music Giacinto Scelsi rejected the mediation of notation, improvising his works and viewing the scores, produced mostly by assistants, as a mere record. But to what extent did he really transcend the ‘tyranny of writing’ and how might one demonstrate this? Critics have tended to echo the composer in reducing the problem to an opposition between writing and sound per se. In this article I discuss the limitations of this view and propose a more structural approach, using in particular the analysis of Walter Ong. I argue that Scelsi's idiom, while novel in its extreme economy of means, uses these means in such a way as to restore a traditional sense of musical ‘grammar’. I illustrate the rhetorical versatility of this grammar by contrasting the two apparently similar movements of the Duo of 1965.
TWO RECENT CONTRIBUTIONS AND NEW HORIZONS IN MODERN TIBETAN HISTORY
Authors: Willock Nicole
Published: January 2011

While the literature on modern Tibetan history is far from comprehensive, contributions to this field of studies have been formative over the last twenty years. With an ever-increasing availability of Tibetan-language source material along with new theoretical insights, the horizons for understanding modern Tibetan history are still expanding.
Ist die COPD ein kardiovaskulärer Risikofaktor?
Authors: Clarenbach  , Kohler
Published: January 2011

Die chronisch obstruktive Lungenerkrankung (COPD) ist gekennzeichnet durch einen Entzündungsprozess, welcher eine Flusslimitation in den Atemwegen verursacht und meistens auf die Inhalation von Tabakrauch zurückzuführen ist. Die COPD ist weltweit die fünfthäufigste Todesursache und bis zu 50% der COPD-Patienten sterben an einem kardiovaskulären Ereignis. In Kohortenstudien konnte eine unabhängige Assoziation zwischen dem Grad der Atemflusslimitation und kardiovaskulären Erkrankungen auch nach Korrektur für klassische Risikofaktoren wie Rauchen und Cholesterinspiegel gezeigt werden. Verschiedene Mechanismen der Gefässschädigung werden bei COPD postuliert. Hierzu zählen die systemische Entzündung, Hypoxie, oxidativer Stress, Sympathikusaktivierung und Veränderungen der Gefäss-Bindegewebsmatrix. Die Evidenz für eine kausale Beziehung zwischen COPD und kardiovaskulärer Erkrankung fehlt jedoch weitgehend und es werden dringend Ergebnisse von kontrollierten Studien zu den postulierten Pathomechanismen benötigt.
Eine seltene Differentialdiagnose der zervikalen Lymphadenopathie
Authors: Hinder  , Hitz  , Brugnolaro  , Stöckli
Published: January 2011

Wir beschreiben eine 15-jährige Patientin mit einer langsam wachsenden, leicht schmerzhaften Schwellung am Hals, ohne Entzündungszeichen und ohne Allgemeinsymptome. Sonographisch fanden sich zwei vergrösserte Lymphknoten mit erhaltener Hiluszeichnung. Mithilfe der Histologie konnte schliesslich die Diagnose eines Morbus Castleman vom hyalin vaskulären Typ gestellt werden. Es werden die Differentialdiagnose der Schwellung am Hals sowie Klinik, Diagnostik, Pathogenese und Therapie des M. Castleman beschrieben. Der Morbus Castleman ist eine seltene Differentialdiagnose der nicht infektiösen zervikalen Lymphadenopathie. Die Therapie des unizentrischen Morbus Castleman liegt in der chirurgischen Resektion. Bei Kontraindikationen ist alternativ eine Radiotherapie zu diskutieren. Multizentrische Formen sind Systemerkrankungen mit schlechter Prognose und müssen interdisziplinär behandelt werden.
Selection and placement of best management practices used to reduce water quality degradation in Lincoln Lake watershed
Authors: Rodriguez Hector German , Popp Jennie , Maringanti Chetan , Chaubey Indrajeet
Published: January 2011

An increased loss of agricultural nutrients is a growing concern for water quality in Arkansas. Several studies have shown that best management practices (BMPs) are effective in controlling water pollution. However, those affected with water quality issues need water management plans that take into consideration BMPs selection, placement, and affordability. This study used a nondominated sorting genetic algorithm (NSGA‐II). This multiobjective algorithm selects and locates BMPs that minimize nutrients pollution cost‐effectively by providing trade‐off curves (optimal fronts) between pollutant reduction and total net cost increase. The usefulness of this optimization framework was evaluated in the Lincoln Lake watershed. The final NSGA‐II optimization model generated a number of near‐optimal solutions by selecting from 35 BMPs (combinations of pasture management, buffer zones, and poultry litter application practices). Selection and placement of BMPs were analyzed under various cost solutions. The NSGA‐II provides multiple solutions that could fit the water management plan for the watershed. For instance, by implementing all the BMP combinations recommended in the lowest‐cost solution, total phosphorous (TP) could be reduced by at least 76% while increasing cost by less than 2% in the entire watershed. This value represents an increase in cost of $5.49 ha−1 when compared to the baseline. Implementing all the BMP combinations proposed with the medium‐ and the highest‐cost solutions could decrease TP drastically but will increase cost by $24,282 (7%) and $82,306 (25%), respectively.
Visualization of Cell Death in MICE with Focal Cerebral Ischemia using Fluorescent Annexin A5, Propidium Iodide, and Tunel Staining
Authors: Bahmani Peyman , Schellenberger Eyk , Klohs Jan , Steinbrink Jens , Cordell Ryan , Zille Marietta , Müller Jochen , Harhausen Denise , Hofstra Leo , Reutelingsperger Chris , Farr Tracy Deanne , Dirnagl Ulrich , Wunder Andreas
Published: January 2011

To monitor stroke-induced brain damage and assess neuroprotective therapies, specific imaging of cell death after cerebral ischemia in a noninvasive manner is highly desirable. Annexin A5 has been suggested as a marker for imaging cell death under various disease conditions including stroke. In this study, C57BL6/N mice received middle cerebral artery occlusion (MCAO) and were injected intravenously with either active or inactive Cy5.5-annexin A5 48 hours after reperfusion. Some mice also received propidium iodide (PI), a cell integrity marker. Only in mice receiving active Cy5.5-annexin A5 were fluorescence intensities significantly higher over the hemisphere ipsilateral to MCAO than on the contralateral side. This was detected noninvasively and ex vivo 4 and 8 hours after injection. The majority of cells positive for fluorescent annexin A5 were also positive for PI and fragmented DNA as detected by terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate-biotin nick end labeling (TUNEL) staining. This study demonstrates the high specificity of annexin A5 for visualization of cell death in a mouse model of stroke. To our knowledge, this is the first study to compare the distribution of injected active and inactive annexin A5, PI, and TUNEL staining. It provides important information on the experimental and potential clinical applications of annexin A5-based imaging agents in stroke.
Pseudocontinuous Arterial Spin Labeling Reveals Dissociable Effects of Morphine and Alcohol on Regional Cerebral Blood Flow
Authors: Khalili-Mahani Najmeh , van Osch Matthias JP , Baerends Evelinda , Soeter Roelof P , de Kam Marieke , Zoethout Remco WM , Dahan Albert , van Buchem Mark A , van Gerven Joop MA , Rombouts Serge ARB
Published: January 2011

We have examined sensitivity and specificity of pseudocontinuous arterial spin labeling (PCASL) to detect global and regional changes in cerebral blood flow (CBF) in response to two different psychoactive drugs. We tested alcohol and morphine in a placebo-controlled, double-blind randomized study in 12 healthy young men. Drugs were administered intravenously. Validated pharmacokinetic protocols achieved minimal intersubject and intrasubject variance in plasma drug concentration. Permutation-based statistical testing of a mixed effect repeated measures model revealed a widespread increase in absolute CBF because of both morphine and alcohol. Conjunction analysis revealed overlapping effects of morphine and alcohol on absolute CBF in the left anterior cingulate, right hippocampus, right insula, and left primary sensorimotor areas. Effects of morphine and alcohol on relative CBF (obtained from z-normalization of absolute CBF maps) were significantly different in the left putamen, left frontoparietal network, cerebellum, and the brainstem. Corroborating previous PET results, our findings suggest that PCASL is a promising tool for central nervous system drug research.
Toward a Complete Phyloreferencing Language
Authors: Keesey T. Michael
Published: January 2011

A phyloreference is a statement indicating a taxon within a phylogenetic context. A common use for phyloreferences is in phylogenetic definitions, which tie taxonomic names to taxa via such statements. Several conventions for writing phyloreferences have been proposed, but most only cover a few “standard” forms (node‑, branch‑, and perhaps apomorphy‑based clades) without the capacity to represent more “exotic” forms (e.g., ancestor‑based clades and qualified/modified references). In order to build a complete phyloreferencing language, the mathematical underpinnings of phylogenetic contexts must be clarified. A phylogenetic context may be modeled as a directed, acyclic graph, wherein nodes model taxonomic units and directed edges model immediate descent. Higher taxa are modeled as unions of nodes. A phyloreferencing language must minimally allow for certain classes of entity: Boolean values, sets (including taxa, relations, and the empty set), and lists (including graphs and functions). It must also minimally allow for basic operations related to logic, set theory, and graph theory. Higher structures such as declarations and piecewise constructs must also be possible. With these as a basis, functions related to phylogeny can be defined: maximal, minimal, predecessor union/intersection, successor union/intersection, exclusive predecessors, synapomorphic predecessors, clade, crown clade, and total clade. I show how such a language may be used to represent various types of phyloreference, both “standard” and “exotic”.
A study of the relation between translational and rotational diffusion through measurement of molecular recollision
Authors: Kurban Mark R.
Published: January 2011

Translational and rotational diffusion rates of perdeuterated tempone (PDT) in ethanol are determined using electron paramagnetic resonance spectroscopy. The translational motion is measured on two scales: the macroscopic, as represented by the Heisenberg spin-exchange rate, and the microscopic, which entails recollisions between the same spin-exchange particle pair. The spin-exchange and recollision rates are used together to calculate the overall translational diffusion coefficient without recourse to assumptions concerning the value of the Stokes radius or collision distance. When observed as a function of solvent isothermal compressibility, the recollision time in ethanol is displaced from the common alkane curve at low temperatures but joins that curve at higher temperatures. Rotational correlation times in ethanol are obtained and show a decreasing rotation–translation coupling with increasing temperature, revealing a pattern that is qualitatively identical with respect to both collision and recollision. In comparison, an examination of PDT diffusion in toluene reveals an increasing rotation–translation coupling with increasing temperature. The contrasting behavior of the coupling in the two solvents is attributable to the degree of anisotropy in PDT rotation.
Development of electroluminescence based pressure-sensitive paint system
Authors: Iijima Yoshimi , Sakaue Hirotaka
Published: January 2011

We introduce a pressure-sensitive paint (PSP) measurement system based on an electroluminescence (EL) as a surface illumination. This consists of an inorganic EL as the illumination, a short-pass filter, and a platinum–porphyrin based PSP. The short-pass filter, which passes below 500 nm, was used to separate an overlay of the EL illumination and the PSP emission. The EL shows an opposite temperature dependency to that of the PSP. It gives a uniform illumination compared to that of a point illumination source such as a xenon lamp. Under atmospheric conditions, the resultant EL–PSP system reduces the temperature dependency by 54% compared to that of a conventional PSP system. An application of the EL–PSP system to a sonic jet impingement shows that the system demonstrated its reduction of the temperature dependency by 75% in a pressure measurement and reduces an image misalignment error.
Rotational spectroscopy and molecular structure of the 1-chloro-1-fluoroethylene-acetylene complex
Authors: Leung Helen O. , Marshall Mark D. , Grimes David D.
Published: January 2011

Guided by ab initio calculations, Fourier transform microwave spectra in the 6–21 GHz region are obtained for seven isotopomers of the complex formed between 1-chloro-1-fluoroethylene and acetylene. These include the four possible combinations of 35Cl- and 37Cl-containing CH2CClF with the most abundant acetylene isotopic modification, HCCH, and its H13C13CH analogue, as well as three singly substituted deuterated isotopomers. Analysis of the spectra determines the rotational constants and additionally, the complete chlorine quadrupole hyperfine coupling tensors in both the inertial and principal electric field gradient axis systems, and where appropriate, the diagonal components of the deuterium quadrupole coupling tensors. The inertial information contained in the rotational constants provides the structure for CH2CClF–HCCH: a primary, hydrogen bonding interaction existing between the HCCH donor and the F atom acceptor on the 1-chloro-1-fluoroethylene moiety, while a secondary interaction occurs between the acetylenic bond on the HCCH molecule and the H atom cis to the hydrogen-bonded F atom on the substituted ethylene, which causes the hydrogen bond to deviate from linearity. This is similar to the structure obtained for 1,1-difluoroethylene-HCCH [H. O. Leung and M. D. Marshall, J. Chem. Phys. 126, 154301 (2006)], and indeed, to within experimental uncertainty, the intermolecular interactions in CH2CClF–HCCH and its 1,1-difluoroethylene counterpart are practically indistinguishable, even though ab initio calculations at the MP2/6-311G++(2d, 2p) level suggest that the former complex is more strongly bound.
Effect of deoxyribonucleic acid on nonlinear optical properties of Rhodamine 6G-polyvinyl alcohol solution
Authors: Nithyaja B. , Misha H. , Radhakrishnan P. , Nampoori V. P. N.
Published: January 2011

We have investigated the effect of DNA on nonlinear optical properties of Rhodmine6G-PVA solution through open aperture Z-scan. We observed saturable absorption (SA) at 532 nm for dye solution without DNA. A strong influence on SA behavior of dye solution was observed by adding DNA. As the concentration of DNA (2 wt %) increased, we observed RSA within SA. The sample shows SA behavior away from focus and RSA behavior near the focus. Theoretical analysis has been performed using a model based on nonlinear absorption coefficient and saturation intensity. The result of present study gives an additional mechanism for the gain enhancement in dye doped DNA matrix.
Note: Relaxation heat capacity measurements at low temperatures: Dealing with nuclear contribution
Authors: Andraka B. , Takano Y.
Published: January 2011

Nuclear heat capacity is a serious obstacle in low temperature heat capacity measurements by a relaxation technique. However, this method allows an experimenter to measure the electronic heat capacity directly, if the ratio of electronic heat capacity to the conductance of the calorimeter is sufficiently small in comparison with nuclear-spin relaxation times. This is because the initial rate of a temperature decay is always determined by the electronic degrees of freedom and does not depend on nuclear degrees of freedom. This previously unrecognized feature is clearly demonstrated through measurements of Cu in external magnetic fields.
Intermediates of CO oxidation on iron oxides: An experimental and theoretical study
Authors: Lu Zhang-Hui , Xu Qiang
Published: January 2011

Reactions of laser-ablated iron oxides with CO in excess argon are investigated by infrared adsorption spectroscopy and density functional theoretical calculations. The carbonyl iron oxides OFe(CO)n (n = 1–3) and O2Fe(CO)m (m = 1, 2) are generated during sample deposition or annealing, whereas CO2 is greatly produced at the expense of these carbonyl iron oxides upon UV irradiation, showing the formation of intermediate carbonyl iron oxides in the oxidation of carbon monoxide to carbon dioxide. These intermediate carbonyl iron oxides are characterized on the basis of isotopic substitution, stepwise annealing, change of CO concentration and laser energy, and comparison with theoretical calculations. The overall agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts supports the identification of these complexes from the matrix infrared spectra. The reaction pathways for the formation of the products are proposed based on the experimental and theoretical results presented.
Three-dimensional extended Hückel theory-nonequilibrium Green’s function spin polarized transport model for Fe/MgO/Fe heterostructures
Authors: Raza Tehseen Z. , Cerdá Jorge I. , Raza Hassan
Published: January 2011

Although the theory of tunnel magnetoresistance (TMR) in Fe/MgO/Fe heterostructures is well known, there is a discrepancy between the values predicted by ab initio calculations with a band gap of 5.2 eV and the ones predicted by other methods, e.g., empirical tight-binding with a band gap of 7.6 eV. To our knowledge, no one has yet used the same theory to explore the reasons behind this discrepancy. In this work, we report a three-dimensional atomistic nonequilibrium Green’s function transport model with two set of transferable extended Hückel theory parameters for MgO; one with the experimental band gap of 7.8 eV and the other with the local density approximation of the density functional theory band gap of 5.2 eV. To capture the symmetry filtering property of MgO, we parameterize using the k-resolved orbital projected density of states as the benchmark. We show that the band gap has a significant effect on the barrier width dependence and the bias dependence of the transport quantities. By using the experimental band gap, the TMR is much smaller than the one observed with a band gap of 5.2 eV.
Sellmeier and thermo-optic dispersion formulas for CsTiOAsO4
Authors: Mikami Takuya , Okamoto Takayuki , Kato Kiyoshi
Published: January 2011

CsTiOAsO 4 has been found to be phase-matchable for type-2 second-harmonic generation and sum-frequency generation in the 0.5321–1.5915 μm range at 20.0 °C. The Sellmeier equations that correctly reproduce these experimental data as well as the 90° phase-matched optical parametric oscillator wavelengths in the 0.7337–2.4793 μm range are presented together with the thermo-optic dispersion formula.
Enhanced photorefractivity in a polymeric composite photosensitized with carbon nanotubes grafted to a photoconductive polymer
Authors: Lingam Naveen K. , Kalghatgi Sonali , Winiarz Jeffrey G.
Published: January 2011

We report on the photosensitization of photorefractive (PR) polymeric composites through the inclusion of multiwalled and singlewalled carbon nanotubes (CNTs), respectively, having poly(N-vinyl carbazole) (PVK) grafted to their surfaces. The PR nature of the holographic gratings was confirmed via the asymmetric exchange of energy in a two-beam-coupling (TBC) geometry, yielding TBC gain coefficients approaching 80 cm−1. In addition, in degenerate-four-wave-mixing experiments the prepared composites exhibited diffraction efficiencies as high as 60% and overmodulation voltages as low as ∼40 V/μm. These notable figures of merit indicate that the grafting of the PVK polymer to the various CNTs results in enhanced PR performance. The mechanism responsible for this enhancement in PR performance is investigated using a variety of experimental techniques.
Strong spin–orbit effects in small Pt clusters: Geometric structure,magnetic isomers and anisotropy
Authors: Błoński Piotr , Dennler Samuel , Hafner Jürgen
Published: January 2011

Ab initio density functional calculations including spin–orbit coupling (SOC) have been performed for Pt\documentclass[12pt]{minimal}\begin{document}$_n$\end{document}n, n = 2–6 clusters. The strong SOC tends to stabilize planar structures for n = 2–5, whereas for clusters consisting of six atoms,three-dimensional structures remain preferred. SOC leads to the formation of large orbital magnetic moments and to a mixing of different spin states. Due to the spin-mixing the total magnetic moment may be larger or smaller than the spin moment in the absence of SOC. Both spin and orbital moments are found to be anisotropic. Because of the strong SOCthe energy differences between coexisting magnetic isomers can be comparable to or even smaller than their magnetic anisotropy energies. In this case the lowest barrier for magnetization reversal can be determined by a magnetic isomer which is different from the ground state configuration.
Effect of impurity doping at the Mn-site on magnetocaloric effect in Pr0.6Ca0.4Mn0.96B0.04O3 (B=Al, Fe, Cr, Ni, Co, and Ru)
Authors: Kumar V. Suresh , Mahendiran R.
Published: January 2011

We report the effect of impurity doping at the Mn-site on magnetization and magnetic entropy change (ΔSm) in Pr0.6Ca0.4Mn0.96B0.04O3 with B cations having different electronic and spin states [B=Al3+(d0), Cr3+(d3), Fe3+(d5), Co2+(d7), Ni2+(d8), and Ru4+/5+(d4/3)]. The charge ordered antiferromagnetic insulator Pr0.6Ca0.4MnO3 transforms into a ferromagnetic metal in the absence of an external magnetic field (H) for B=Cr, Ni, Co, and Ru, whereas B=Fe and Al samples remain as antiferromagnetic insulators. It is found that the applied magnetic field induced an abrupt increase in the magnetization above a critical value of H (field-induced metamagnetic transition) in the paramagnetic state for B=Cr, Ni, and Co but not for B=Ru, which has the highest Curie temperature in the series (TC=205 K). The B=Co sample shows the maximum value of the magnetic entropy (−ΔSm=7.37 J/kg K under ΔH=5 T), which is followed by −ΔSm=6.77,6.0,5.07,5.04,2.72 J/kg K for B=Ni, Cr, Ru, Fe, and Al, respectively. We have also found a large magnetic entropy change (−ΔSm=8.42 J/kg K under ΔH=5) by differential scanning calorimetric study in B=Co sample. The large ΔSm values in B=Co, Cr, and Ni compared to Ru originate from the distinct field dependence of the magnetization above TC. It is suggested that both charge-orbital fluctuations and ferromagnetic polarons exist in the paramagnetic phase of B=Co, Cr, and Ni samples in the absence of a magnetic field, and the external magnetic field suppresses charge-orbital fluctuations and enhances size of ferromagnetic polarons, which leads to observed large ΔSm values. Our study suggests that creation of charge-orbital fluctuations and ferromagnetic polarons by dilution of the Mn-site could be a simple way to enhance the magnetocaloric effect in charge ordered manganites.
Stability in the memory state of the silica nanoparticle-doped hybrid aligned nematic device
Authors: Huang Chi-Yen , Chen Jian-Hong , Hsieh Chia-Ting , Song Heng-Cheng , Wang Yu-Wu , Horng Lance , Tian Ching-Jui , Hwang Shug-June
Published: January 2011

We investigate the stability in the memory state of the silica nanoparticle doped hybrid aligned nematic (SN-HAN) cell. The mixed polyimide (PI)-coated planar substrate provides the SN-HAN cell with a stable memory state. The mixed PI comprises the homogeneous PI and small amounts of the homeotropic PI (H-PI). The tiny H-PI dopant decreases the surface energy, increases the roughness of the planar substrate, and increases the pretilt angle of the liquid crystals (LCs). When the pretilt angle is high, the relaxation torque that rewinds the LCs from the electrically addressed homeotropic state to the originally HAN state is too small to break the formed aggregated silica networks, which stabilize the LCs at the electrically addressed homeotropic state. Consequently, the memory state of the SN-HAN cell is stable when the pretilt angle of the LCs is high.
Systematic study of sensitized LaF3:Eu3+ nanoparticles
Authors: Janssens S. , Williams G. V. M. , Clarke D.
Published: January 2011

We have performed a systematic structural, vibrational, and optical study of LaF3:Eu3+ nanoparticles capped with oleic acid (OA) or OA and sensitized with thenoyltrifluoroacetone (TTA). The average nanoparticle size was around 11 nm for all Eu3+ concentrations. A shift in the energy of the Raman active modes is observed with increasing Eu3+ concentration that can be accounted for by a decrease in the unit cell volume. Sensitization by TTA was observed and resulted in an 18 000% increase in the photoluminescence (PL) intensity for TTA/OA capped LaF3:Eu3+ nanoparticles when compared with OA capped LaF3:Eu3+ nanoparticles. There is also a large increase in the D50→F72 PL intensity, when normalized to the D50→F71 PL magnetic dipole transition intensity, for TTA/OA capped nanoparticles. The changes in the PL intensities, PL lifetimes, Judd–Ofelt parameters, stimulated emission cross sections, and quantum efficiencies, for OA and TTA/OA capped LaF3:Eu3+ nanoparticles with increasing Eu3+ concentration can be accounted for by a model that separates the Eu3+ sites into sites near the surface and Eu3+ sites in the core as well as nonradiative recombination sites near the surface. The large increase in PL intensity due to TTA sensitization means that TTA capped LaF3:Eu3+ can potentially be used for applications that include optical amplification.
Anisotropic mechanism on distinct transition modes of tip-activated multipolorizaion switching in epitaxial BiFeO3 films
Authors: Shi Y. P. , Soh A. K. , Weng G. J.
Published: January 2011

Based on the extended Kittel’s law, an anisotropic mechanism has been developed to investigate the complex multipolarization switching in (001) and (110) epitaxial BiFeO3 films, under a biased-tip field. Switching inhomogeneity and domain wall width evolution have been specifically accounted for. It has been found that distinct switching modes, i.e., the breakdown mode of 71°-switched domain and the activation mode of 180°/109° switching, exist and dominate the switching orders within switching process. Our predicted switching orders show excellent agreements with the existing experimental data and phase-field results. A two-step procedure is also proposed to fabricate single-phase 71° ferroelastic domain array of controllable density using (001) BiFeO3 films, which is favored in practice to significantly enhance the magnetoelectric coupling and photovoltage.
Spin transport through a quantum network: Effects of Rashba spin-orbit interaction and Aharonov–Bohm flux
Authors: Dey Moumita , Maiti Santanu K. , Karmakar S. N.
Published: January 2011

We address spin dependent transport through an array of diamonds in the presence of Rashba spin-orbit (SO) interaction where each diamond plaquette is penetrated by an Aharonov–Bohm (AB) flux ϕ. The diamond chain is attached symmetrically to two semi-infinite one-dimensional nonmagnetic metallic leads. We adopt a single particle tight-binding Hamiltonian to describe the system and study spin transport using Green’s function formalism. After presenting an analytical method for the energy dispersion relation of an infinite diamond chain in the presence of Rashba SO interaction, we study numerically the conductance-energy characteristics together with the density of states of a finite sized diamond network. At the typical flux ϕ=ϕ0/2, a delocalizing effect is observed in the presence of Rashba SO interaction, and, depending on the specific choices of SO interaction strength and AB flux the quantum network can be used as a spin filter. Our analysis may be inspiring in designing spintronic devices.
Effects of pH on heat transfer nanofluids containing ZrO2 and TiO2 nanoparticles
Authors: Wamkam Carine Tchamakam , Opoku Michael Kwabena , Hong Haiping , Smith Pauline
Published: January 2011

In this paper, pH influences of zeta potential, particle size distribution, rheology, viscosity, and stability on heat transfer nanofluids are studied. Significant enhancement of thermal conductivity (TC) (>20%) containing 3 wt % zirconium dioxide (ZrO2) and titanium dioxide (TiO2) are observed near the isoelectric point (IEP). Meanwhile, at this IEP (pH), particle sizes, and viscosities of these nanofluids demonstrate a significant increase to maximum values. Experimental results also indicate that the stabilities of these nanofluids are influenced by pH values. The reasonable explanation for these interesting phenomena is that at this IEP, the repulsive forces among metal oxides are zero and nanoparticles coagulate together at this pH value. According to the Derjaguin–Landau–Verwey–Overbeek theory, when the pH is equal to or close to the IEP, nanoparticles tend to be unstable, form clusters, and precipitate. The resulting big clusters will trap water and the structures of trapped water are varied due to the strong atomic force among nanoparticles. Water is packed well inside and volume fraction of the nanoparticles will be larger. In addition, shapes of clusters containing trapped water will not be spherical but rather has irregular structure (like chains). Such structure favors thermal transport because they provide a long link. Therefore, overall TC of nanofluids is enhanced. Some literature results and conclusions related to pH effects of nanofluids are discussed and analyzed. Understanding pH effects may enable exploration of fundamental nature of nanofluids.
Rashba-induced spin accumulation in a quantum wire with an impurity
Authors: Zhang Sha , Gong Weijiang , Wei Guozhu , Du An
Published: January 2011

In this work, we study the properties of the Rashba-induced spin accumulation in a quantum wire, by considering an impurity in this system. First, in the zero-impurity case, the dependence of the spin accumulation on the structure parameters is shown, it is consequently found that in addition to the quantum interference, the spin accumulation is determined by the quantum-wire bandwidth and the external bias. Next we, respectively, consider the cases of the impurity in the Rashba region and the normal region to present the effect of the impurity on the spin accumulation. We see that the impurity destroys the spin accumulation in a nontrivial way, and its influence on the spin accumulation is tightly associated with the coupling manners and strengths between the impurity and the quantum wire and the impurity energy.
Mechanical properties and chemical bonding characteristics of Cr7C3 type multicomponent carbides
Authors: Xiao B. , Feng J. , Zhou C. T. , Jiang Y. H. , Zhou R.
Published: January 2011

The first principles calculations based on density functional theory are performed to investigate the mechanical properties and chemical bonding features of several Cr7C3 type multicomponent carbides (Fe16Cr12C12, Fe12Cr12W4C12, Fe12Cr12Mo4C12, Fe12Cr12W4C8B4, and Fe12Cr12Mo4C8B4). The full set elastic constants are calculated using stress-strain method. The Voigt–Reuss–Hill approximation is used to evaluate the mechanical moduli. The mechanical anisotropy is characterized by calculating several different anisotropic indexes and factors, such as universal anisotropic index (AU), shear anisotropic factors (A1, A2, and A3), and percent anisotropy (AB and AG). The surface constructions of bulk and Young’s moduli are illustrated to indicate the mechanical anisotropy. The obtained results indicate that the presence of B could deteriorate the mechanical moduli of (Fe,Cr)7C3 phase in Cr cast iron slightly. On the other hand, the chemical stability of (Fe,Cr)7C3 carbides is improved due to chemical bonding modifications through doping with B. These conclusions are in agreement with experimental results.
Ion irradiation effects on the exchange bias in IrMn/Co films
Authors: Schafer D. , Grande P. L. , Pereira L. G. , Geshev J.
Published: January 2011

The present work reports on the influence of ion irradiation in exchange-coupled bilayers. Magnetron-sputtered IrMn4/Co films were irradiated with 40 keV He+ ions and the dependence of their magnetic properties was studied as function of ion fluence and current used during the irradiations. The effects of ion damage and electronic excitation were also studied through additional irradiations with H+ and Ne+ ions. The results show a clear dependence of the exchange-bias field on the defects caused by the ion bombardment. No correlations with other irradiation effects were observed.
Effects of nitrogen incorporation on the electronic structure of rutile-TiO2
Authors: Chai J. W. , Yang M. , Chen Q. , Pan J. S. , Zhang Z. , Feng Y. P. , Wang S. J.
Published: January 2011

By direct atomic nitrogen (N) doping, high concentration of N is incorporated into TiO2 and the doping effects are investigated. High resolution x-ray photoelectron spectroscopy core-level spectra indicate N substitution for O and formation of Ti–N bonds. Different Ti valent states are found at different N concentrations. Although the shape of the valence spectra changes significantly up on N doping, the band gap narrowing effect is insignificant. First-principles calculations confirm formation of Ti 3d gap states when N concentration exceeds 1 at. %, which leads to pinging of N 2p states in the band gap.
Nonlinear absorption of InN/InGaN multiple-quantum-well structures at optical telecommunication wavelengths
Authors: Naranjo F. B. , Kandaswamy P. K. , Valdueza-Felip S. , Calvo V. , González-Herráez M. , Martín-López S. , Corredera P. , Méndez J. A. , Mutta G. R. , Lacroix B. , Ruterana P. , Monroy E.
Published: January 2011

We report on the nonlinear optical absorption of InN/InxGa1−xN (x=0.8,0.9) multiple-quantum-well structures characterized at 1.55 μm by the Z-scan method in order to obtain the effective nonlinear absorption coefficient (α2) of the samples at high repetition rate. Saturable absorption is observed for the sample with x=0.9, with an effective α2∼−9×103 cm/GW for the studied optical regime. For lower In content in the barrier, reverse saturable absorption is observed, which is attributed to two-photon absorption.
Probing the atomic structure of amorphous Ta2O5 coatings
Authors: Bassiri R. , Borisenko K. B. , Cockayne D. J. H. , Hough J. , MacLaren I. , Rowan S.
Published: January 2011

Low optical and mechanical loss Ta2O5 amorphous coatings have a growing number of applications in precision optical measurements systems. Transmission electron microscopy is a promising way to probe the atomic structure of these coatings in an effort to better understand the causes of the observed mechanical and optical losses. Analysis of the experimental reduced density functions using a combination of reverse Monte Carlo refinements and density functional theory molecular dynamics simulations reveals that the structure of amorphous Ta2O5 consists of clusters with increased contribution from a Ta2O2 ring fragment.
Enhanced difference in switching fields for perpendicular magnetic spin valves with a composite [Co/Ni]N/TbCo reference layer
Authors: Liao Jialin , He He , Zhang Zongzhi , Ma Bin , Jin Q. Y.
Published: January 2011

A perpendicularly exchange-coupled composite structure, which consists of a [Co/Ni]N multilayer and a ferrimagnetic TbCo layer, displays specific features when it is utilized as a reference layer in spin valves. By slightly increasing the TbCo thickness, the coercivity of the coupled structure greatly increases, thereby giving an effective way to widen the difference in switching fields for the free and reference layers, and making it possible to manipulate magnetizations parallel or antiparallel for a wide range of fields. Such composite reference layer cannot only maintain a high perpendicular giant magnetoresistive (GMR) ratio, but it also minimizes the field offset in the minor GMR curves due to the negligible stray field generated by the antiferromagnetically aligned moments in the reference layer.
Study of field emission, electrical transport, and their correlation of individual single CuO nanowires
Authors: Shao PengRui , Deng ShaoZhi , Chen Jun , Chen Jian , Xu NingSheng
Published: January 2011

We report our recent findings from the study of the field emission, electrical transport, and their correlation of individual single CuO nanowires grown by thermal oxidation. Typical Fowler–Nordheim (FN) plot of a single CuO nanowire exhibits an upward bending behavior with increasing applied electric field: a rare phenomenon of field emission from nanowires. The electrical transport measurement has shown that the CuO nanowire has a typical conductivity of 7.8×10−4 (Ω cm)−1. X-ray photoelectron spectroscopy study has given the energy band gap of 1.2 eV with Fermi energy level close to the top of valence band, confirming that the CuO nanowire is p-type. The upward bending FN plot can be explained using a field emission model of p-type semiconductor.