bluuebunny/crossref_metadata_2025 huggingface dataset:
China's Defence Industrial Base in 1985
Authors: Bachman David
Published: May 2013

This essay assesses various dimensions of China's defence industrial enterprises. It argues that the defence industrial system should be divided into two tiers: tier one, composed of weapons and equipment producers for the military, and tier two, composed of “civilian” industrial enterprises that provided critical inputs for tier one enterprises, and which in national emergencies could be mobilized to produce weapons themselves. In 1985, there were 1,158 tier one defence enterprises and 827 tier two enterprises among China's 8,285 large- and medium-scale enterprises. Additional information is provided on defence enterprise shares of the economy at the provincial and the national levels, on enterprise distribution by industrial sector, and on when enterprises were built. The article attempts to estimate the total number of workers, output value and fixed assets of the defence industrial sector, and their weight in the national economy.
The Estimation of Angular Misalignments for Ultra Short Baseline Navigation Systems. Part I: Numerical Simulations
Authors: Chen Hsin-Hung
Published: May 2013

Ultra Short Baseline (USBL) navigation systems are often faced with positioning errors arising from misalignments between sensors. This paper proposes a line survey method for USBL angular alignment calibration. In the scheme of USBL line survey, mathematical representations of positioning error arising from heading, pitch and roll misalignments are derived, respectively. The effect of each misalignment angle and how the differences can be used to calibrate each misalignment angle in turn are presented. An iterative algorithm that takes advantage of the geometry of position errors resulting from angular misalignments is developed for USBL calibration. Numerical simulations are provided to demonstrate the effectiveness of the USBL line survey approach. In addition, the effect of measurement error on the estimation of roll alignment error is evaluated and discussed.
An outbreak of cryptosporidiosis at a swimming club – can rapid field epidemiology limit the spread of illness?
Authors: McCANN R. , JONES R. , SNOW J. , CLEARY P. , BURGESS S. , BOTHRA V. , CHALMERS R. M.
Published: May 2013

In September 2010, an outbreak of cryptosporidiosis affected members of a swimming club. A cohort study was undertaken to identify the number affected and risk factors for infection. Of 101 respondents, 48 met the case definition for probable cryptosporidiosis. Multivariate analysis demonstrated a strong and highly significant association between illness and attendance at a training session on 13 September 2010 (adjusted odds ratio 28, P < 0·0001). No faecal incidents were reported and pool monitoring parameters were satisfactory. The competitive nature of club swimming requires frequent training and participation in galas, potentially facilitating contamination into other pools and amplification of outbreaks among wider groups of swimmers. There was a lack of awareness of the 2-week exclusion rule among swimmers and coaches, and a high level of underreporting of illness. The study demonstrates the benefits of rapid field epidemiology in identifying the true burden of illness, the source of infection and limiting spread.
Summertime fluxes of N2O, CH4and CO2from the littoral zone of Lake Daming, East Antarctica: effects of environmental conditions
Authors: Ding Wei , Zhu Renbin , MA Dawei , Xu Hua
Published: May 2013

Nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) fluxes were investigated from the algal-rich littoral zone of Lake Daming, East Antarctica during the summers of 2008/09 and 2009/10, using a static chamber technique. High N2O emissions occurred in the littoral zone with the mean flux range of 0.19–7.11 μmol N2O m-2h-1. The mean CH4fluxes ranged from 2.51–5.32 μmol CH4m-2h-1, and they were significantly affected by the lake thermal regime. There were significant differences (P< 0.05) in CH4and N2O fluxes under the light and dark conditions, and sunlight greatly increased N2O emissions by stimulating the algal photosynthesis, but decreased CH4emissions. Overall the littoral zone represented a weak CO2sink with the mean flux range of -0.37–0.13 mmol CO2m-2h-1. The mean ecosystem respiration and photosynthesis rates varied from 0.47–2.90 mmol CO2m-2h-1and from -0.33 to -2.63 mmol CO2m-2h-1. The combined global warming potential (GWP) of N2O and CH4fluxes completely counteracted and surpassed CO2uptake by the algal photosynthesis, and high GWP-positive of N2O and CH4emissions might convert an algal-rich lake site with a net CO2uptake into a net radiative forcing source during the ice-free period.
The summer foraging ranges of adult spectacled petrels Procellaria conspicillata
Authors: Reid Tim A. , Ronconi Robert A. , Cuthbert Richard J. , Ryan Peter G.
Published: May 2013

Satellite transmitters were attached to eight adult spectacled petrels Procellaria conspicillata Gould captured during the early incubation period at their breeding grounds on Inaccessible Island, one of the Tristan da Cunha Islands in the central South Atlantic Ocean. Data on their at-sea distribution was obtained for up to six months. All birds remained within the South Atlantic from 24–44°S, with most between 25 and 40°S. Breeding birds mainly foraged in oceanic waters, but failed breeders or non-breeders concentrated their foraging activity over the Rio Grande Rise and the Walvis Ridge and along the shelf break off the east coast of South America. Little foraging occurred along the Benguela shelf break off southern Africa. Non-breeders favoured relatively warm water with low chlorophyll concentrations, reducing the risk of bycatch in fisheries. Tracked birds spent 16% of their time in areas with high levels of tuna longline fishing activity, with overlap greater for non-breeding birds (22%) than breeding birds (3%). Birds in this study foraged in shallower waters along the continental shelf edge off South America than spectacled petrels tracked in this area in winter, potentially increasing their risk of exposure to demersal longline fisheries in this area in summer.
Terrestrial palynomorphs of the Cenozoic Pagodroma Group, northern Prince Charles Mountains, East Antarctica
Authors: Wei L.J. , Raine J.I. , Liu X.H.
Published: May 2013

Terrestrial palynomorphs from the glaciomarine Pagodroma Group provide the first stratigraphically-constrained record of Cenozoic terrestrial vegetation for the northern Prince Charles Mountains, East Antarctica. In general, contemporaneous spores and pollen are extremely sparse, but palynological assemblages of the late middle–late Miocene Fisher Bench Formation and Battye Glacier Formation have relatively more abundant Cenozoic spores and pollen compared with those of the Oligocene Mount Johnston Formation and the Pliocene–early Pleistocene Bardin Bluffs Formation. Spore-pollen assemblages from the Battye Glacier Formation and the Fisher Bench Formation are dominated by Chenopodipollis, with a few other accessory angiosperm and podocarp pollen, pteridophyte and bryophyte spores, and algal cysts, reflecting a low diversity herb-tundra vegetation and a climate similar to the present-day cool to cold sub-Antarctic regions. Reworked Permian–Triassic miospores in Amery oasis (unofficial name) sediments probably indicate local provenance from the Amery Group but Jurassic–Cretaceous and possible early Cenozoic miospores reflect an unknown source.
Equivalence relations for modular performance evaluation in dtsPBC
Authors: TARASYUK IGOR V.
Published: May 2013

We define a number of stochastic equivalences in the dtsPBC framework, which is a discrete time stochastic extension of finite Petri box calculus (PBC) enriched with iteration. These equivalences allow the identification of stochastic processes that have similar behaviour but are differentiated by the semantics of the calculus. We explain how the equivalences we propose can be used to reduce transition systems of expressions, and demonstrate how to apply the equivalences to compare the stationary behaviour. The equivalences guarantee a coincidence of performance indices for stochastic systems, and can be used for performance analysis simplification. We use a case study to outline a method of modelling, performance evaluation and behaviour preserving reduction of concurrent computing systems, and apply it to the dining philosophers system.
Meiosis progression and donor age affect expression profile of DNA repair genes in bovine oocytes
Authors: Bilotto S. , Boni R. , Russo G.L. , Lioi M.B.
Published: May 2013

Several genetic and physiological factors increase the risk of DNA damage in mammalian oocytes. Two critical events are: (i) meiosis progression, from maturation to fertilization, due to extensive chromatin remodelling during genome decondensation; and (ii) aging, which is associated with a progressive oxidative stress. In this work, we studied the transcriptional patterns of three genes,RAD51,APEX-1andMLH1, involved in DNA repair mechanisms. The analyses were performed by real-time quantitative PCR (RT-qPCR) in immature andin vitromatured oocytes collected from 17 ± 3-month-old heifers and 94 ± 20-month-old cows. Batches of 30–50 oocytes for each group (three replicates) were collected from ovarian follicles of slaughtered animals. The oocytes were freed from cumulus cells at the time of follicle removal, or afterin vitromaturation (IVM) carried out in M199 supplemented with 10% fetal calf serum, 10 IU luteinising hormone (LH)/ml, 0.1 IU follicle-stimulating hormone (FSH)/ml and 1 μg 17β-oestradiol/ml. Total RNA was extracted by Trizol method. The expression of bovineGAPDHgene was used as the internal standard, while primers for bovineRAD51,APEX-1andMLH1genes were designed from DNA sequences retrieved from GenBank. Results obtained indicate a clear up-regulation ofRAD51,APEX-1andMLH1genes after IVM, ranging between two- and four-fold compared with germinal vesicle (GV) oocytes. However, onlyRAD51showed a significant transcript increase between the immature oocytes collected from young or old individuals. This finding highlightsRAD51as a candidate gene marker for discriminating bovine immature oocytes in relation to the donor age.
Self-Discrepancy Monitoring and its Impact on Negative Mood: An Experimental Investigation
Authors: Caselli Gabriele , Decsei-Radu Alina , Fiore Francesca , Manfredi Ciara , Querci Sara , Sgambati Sara , Rebecchi Daniela , Ruggiero Giovanni M. , Sassaroli Sandra
Published: May 2013

Background: The perception of self-discrepancies between the actual self and the ideal self has been defined as a cognitive risk factor for depression (Higgins, 1987). In this view, self-discrepancy monitoring (SDM) refers to the voluntary re-orientation of attention towards detecting discrepancies between ideal and actual selves, even in a positive situation. Aims: The goal of this study was to explore the impact of SDM on levels of mood in the face of positive stimuli. Method: Two clinical and two non-clinical samples were recruited from two different European countries (Italy and Romania). All participants were asked to focus on a past positive experience, and were then randomly allocated to one of two induction tasks. The experimental condition consisted of monitoring discrepancies between personal goals and the recalled positive experience, while the control condition consisted of observing what the participant was feeling. Results: The findings show that, after recalling a positive memory, SDM leads to a significant decrease in mood over a short period independent of the severity of depressive symptoms. This effect is partially mediated by the concurrent change in levels of brooding. Conclusions: Self-discrepancy monitoring in response to positive stimuli tends to lower current mood independent of the initial level of depressive symptoms, and seems to be a global trigger of emotional distress that does not refer only to a depressed cognitive style.
On information dissemination as an informal environmental regulation
Authors: Jamalpuria Aditi
Published: May 2013

The paper analyzes the impact of environmental information dissemination by an information agent in a product market duopoly. The information agent performs the task of disseminating information regarding a green and a polluting firm's environmental profiles to consumers differing in their preferences for the two firms’ products. The result reveals that, in the absence of information dissemination, the green firm earns a lower market share which necessitates the information agent's intervention to encourage the consumption of green product. Moreover, complete information dissemination regarding the green firm's environmental profile is sufficient to generate a higher market share for the green firm. The paper also finds that an increase in information dissemination regarding either of the two firms’ environmental profiles decreases environmental damage accrued to the society and encourages a greener consumption pattern. An eco-efficiency drive is shown to be self-corrective as it negates the need for the informational intervention.
Property rights, tenure security and forest investment incentives: evidence from China's Collective Forest Tenure Reform
Authors: Yi Yuanyuan , Köhlin Gunnar , Xu Jintao
Published: May 2013

This paper assesses how tenure reform in China's collective forest sector affects Chinese farmer households’ perception of tenure security and propensity to invest in their forestland. A large database consisting of information from 3,180 households in eight provinces from south to north is used to explore factors correlated with more strongly perceived tenure security and determinants of forest-related investment. The study adds to the limited research testing whether there is endogenous causality between investment and tenure security in forestland, and finds that investment was not undertaken to enhance tenure security. In addition, the data allow for differentiation between perceived tenure security and contracted use and transferability rights. Overall, stronger contracted rights were found to affect investment. China's forest tenure reform – where individual households can manage forestland, empowered by legal certification and stronger contract rights – has thus enhanced tenure security and encouraged forest investment.
Blood Capillary Length Estimation from Three-Dimensional Microscopic Data by Image Analysis and Stereology
Authors: Kubínová Lucie , Mao Xiao Wen , Janáček Jiří
Published: May 2013

Studies of the capillary bed characterized by its length or length density are relevant in many biomedical studies. A reliable assessment of capillary length from two-dimensional (2D), thin histological sections is a rather difficult task as it requires physical cutting of such sections in randomized directions. This is often technically demanding, inefficient, or outright impossible. However, if 3D image data of the microscopic structure under investigation are available, methods of length estimation that do not require randomized physical cutting of sections may be applied. Two different rat brain regions were optically sliced by confocal microscopy and resulting 3D images processed by three types of capillary length estimation methods: (1) stereological methods based on a computer generation of isotropic uniform random virtual test probes in 3D, either in the form of spatial grids of virtual “slicer” planes or spherical probes; (2) automatic method employing a digital version of the Crofton relations using the Euler characteristic of planar sections of the binary image; and (3) interactive “tracer” method for length measurement based on a manual delineation in 3D of the axes of capillary segments. The presented methods were compared in terms of their practical applicability, efficiency, and precision.
Evaluation of the effects of extended release quetiapine fumarate monotherapy on sleep disturbance in patients with major depressive disorder: a pooled analysis of four randomized acute studies
Authors: Trivedi Madhukar H. , Bandelow Borwin , Demyttenaere Koen , Papakosts George I. , Szamosi Johan , Earley Willie , Eriksson Hans
Published: May 2013

Effects of once-daily extended-release quetiapine fumarate (quetiapine XR) monotherapy on sleep quality and disturbance in patients with major depressive disorder (MDD) were evaluated. Pooled data from four 6- or 8-wk placebo-controlled quetiapine XR (50–300 mg/d) monotherapy studies (D1448C00001; D1448C00002; D1448C00003; D1448C00004) were analysed. Primary efficacy end-point was change from randomization in Montgomery Åsberg Depression Rating Scale (MADRS) score. Post hoc analyses of secondary end-points were conducted for change from randomization in: MADRS item 4 (reduced sleep); Hamilton Rating Scale for Depression (HAMD) items 4 (insomnia-early), 5 (insomnia-middle), 6 (insomnia-late) and sleep disturbance factor (items 4 + 5+6) scores; Pittsburgh Sleep Quality Index (PSQI) global scores. MADRS total score change was also evaluated in patients experiencing high and low baseline sleep disturbance (HAMD sleep disturbance factor scores ⩾4 and < 4, respectively). In total, 1808 patients were randomized to quetiapine XR or placebo across four studies. At last assessment, quetiapine XR reduced MADRS item 4, HAMD items 4, 5 and 6, HAMD sleep disturbance factor score and PSQI global scores from baseline vs. placebo (p < 0.001). For those experiencing high sleep disturbance (n = 865, quetiapine XR; n = 514, placebo), quetiapine XR improved MADRS total score vs. placebo at all visits (p < 0.001). For those with low sleep disturbance (n = 252, quetiapine XR; n = 121, placebo), quetiapine XR improved MADRS total score vs. placebo at weeks 2 (p < 0.001), 4 and 6 (both p < 0.05). In conclusion, quetiapine XR (50–300 mg/d) monotherapy improved symptoms of sleep disturbance vs. placebo in patients with MDD, including those with either high or low baseline sleep disturbance levels.
Evaluation of adjunct extended-release quetiapine fumarate on sleep disturbance and quality in patients with major depressive disorder and an inadequate response to on-going antidepressant therapy
Authors: Bauer Michael , McIntyre Roger S. , Szamosi Johan , Eriksson Hans
Published: May 2013

Sleep disturbance is common in depression and is a risk factor for recurrence and suicide. This analysis evaluated the effects of adjunct extended-release quetiapine fumarate (quetiapine XR) on sleep disturbance and quality in patients with major depressive disorder (MDD) and an inadequate response to on-going antidepressant therapy. Pooled data from two 6-wk, randomized, double-blind, placebo-controlled trials were analysed post hoc. Patients received once-daily quetiapine XR [(150 mg/d), n = 309; (300 mg/d), n = 307] or placebo (n = 303) adjunct to on-going antidepressant therapy. Analyses included: change from randomization in Montgomery-Åsberg Depression Rating Scale (MADRS) Item 4 (reduced sleep) score; Hamilton Rating Scale for Depression (HAMD) Items 4 (insomnia-early), 5 (insomnia-middle) and 6 (insomnia-late) scores; HAMD sleep disturbance factor (Items 4+5+6); Pittsburgh Sleep Quality Index (PSQI) global score. Change in MADRS total score was also evaluated in patients stratified by HAMD sleep disturbance factor score (high ⩾4 and low < 4) at randomization. At week 6, adjunct quetiapine XR (150 and 300 mg/d) reduced MADRS Item 4, HAMD Items 4, 5 and 6, HAMD sleep disturbance factor and PSQI global scores from randomization vs. placebo (all p < 0.001). In patients with high sleep disturbance, quetiapine XR (both doses) improved depressive symptoms (MADRS total score) vs. placebo from week 1 onwards (p < 0.01). Adjunct quetiapine XR improved sleep disturbance and quality vs. placebo in patients with MDD and an inadequate response to on-going antidepressant treatment, and was effective against depressive symptoms in patients experiencing high sleep disturbance.
Biological substrates underpinning diagnosis of major depression
Authors: Sibille Etienne , French Beverly
Published: May 2013

Major depression is characterized by low mood, a reduced ability to experience pleasure and frequent cognitive, physiological and high anxiety symptoms. It is also the leading cause of years lost due to disability worldwide in women and men, reflecting a lifelong trajectory of recurring episodes, increasing severity and progressive treatment resistance. Yet, antidepressant drugs at best treat only one out of every two patients and have not fundamentally changed since their discovery by chance >50 yr ago. This status quo may reflect an exaggerated emphasis on a categorical disease classification that was not intended for biological research and on oversimplified gene-to-disease models for complex illnesses. Indeed, genetic, molecular and cellular findings in major depression suggest shared risk and continuous pathological changes with other brain-related disorders. So, an alternative is that pathological findings in major depression reflect changes in vulnerable brain-related biological modules, each with their own aetiological factors, pathogenic mechanisms and biological/environment moderators. In this model, pathological entities have low specificity for major depression and instead co-occur, combine and interact within individual subjects across disorders, contributing to the expression of biological endophenotypes and potentially clinical symptom dimensions. Here, we discuss current limitations in depression research, review concepts of gene-to-disease biological scales and summarize human post-mortem brain findings related to pyramidal neurons, γ-amino butyric acid neurons, astrocytes and oligodendrocytes, as prototypical brain circuit biological modules. Finally we discuss nested aetiological factors and implications for dimensional pathology. Evidence suggests that a focus on local cell circuits may provide an appropriate integration point and a critical link between underlying molecular mechanisms and neural network dysfunction in major depression.
Credibility of industry-funded clinical trials
Authors: Tohen Mauricio
Published: May 2013

If the pharmaceutical industry does not adhere to strict ethical standards both internally and externally when collaborating with academia, the public's trust will be further eroded.
Measuring the cost of international trade in services
Authors: MIROUDOT SÉBASTIEN , SAUVAGE JEHAN , SHEPHERD BEN
Published: May 2013

We present a new dataset of international trade costs in services sectors. Using a theory-based methodology combined with data on domestic shipments and cross-border trade, we find that trade costs in services are much higher than in goods sectors: a multiple of two to three times in many cases. Trade costs in services have remained relatively steady over the last ten years, whereas trade costs in goods have fallen overall at an impressive rate. We show that even in a regional grouping that has done much to promote a single market in services–the EU–there remains considerable heterogeneity in trade costs across countries. Our findings generally suggest an important role for future policy reforms to reduce the regulatory burdens facing services sectors and facilitate trade in services.
Sample Size Requirements of the Robust Weighted Least Squares Estimator
Authors: Moshagen Morten , Musch Jochen
Published: May 2013

The present study investigated sample size requirements of maximum likelihood (ML) and robust weighted least squares (robust WLS) estimation for ordinal data with confirmatory factor analysis (CFA) models with 3–10 indicators per factor, primary loadings between .4 and .9, and four different levels of categorization (2, 3, 5, and 7). Additionally, the utility of the H-measure of construct reliability (an index combining the number of indicators and the magnitude of loadings) in predicting sample size requirements was examined. Results indicated that a higher number of indicators per factors and higher factor loadings increased the rates of proper convergence and solution propriety. However, the H-measure could only partly account for the results. Moreover, it was demonstrated that robust WLS was mostly superior to ML, suggesting that there is little reason to prefer ML over robust WLS when the data are ordinal. Sample size recommendations for the robust WLS estimator are provided.
Prdm14 promotes germline fate and naive pluripotency by repressing FGF signalling and DNA methylation
Authors: Grabole Nils , Tischler Julia , Hackett Jamie A , Kim Shinseog , Tang Fuchou , Leitch Harry G , Magnúsdóttir Erna , Surani M Azim
Published: May 2013

Primordial germ cells (PGCs) and somatic cells originate from postimplantation epiblast cells in mice. As pluripotency is lost upon differentiation of somatic lineages, a naive epigenome and the pluripotency network are re‐established during PGC development. Here we demonstrate that Prdm14 contributes not only to PGC specification, but also to naive pluripotency in embryonic stem (ES) cells by repressing the DNA methylation machinery and fibroblast growth factor (FGF) signalling. This indicates a critical role for Prdm14 in programming PGCs and promoting pluripotency in ES cells.
skNAC depletion stimulates myoblast migration and perturbs sarcomerogenesis by enhancing calpain 1 and 3 activity
Authors: Berkholz Janine , Zakrzewicz Andreas , Munz Barbara
Published: May 2013

skNAC (skeletal and heart muscle specific variant of nascent polypeptide-associated complex α) is a skeletal and heart muscle-specific protein known to be involved in the regulation of sarcomerogenesis. The respective mechanism, however, is largely unknown. In the present paper, we demonstrate that skNAC regulates calpain activity. Specifically, we show that inhibition of skNAC gene expression leads to enhanced, and overexpression of the skNAC gene to repressed, activity of calpain 1 and, to a lesser extent, calpain 3 in myoblasts. In skNAC siRNA-treated cells, enhanced calpain activity is associated with increased migration rates, as well as with perturbed sarcomere architecture. Treatment of skNAC-knockdown cells with the calpain inhibitor ALLN (N-acetyl-leucyl-leucyl-norleucinal) reverts both the positive effect on myoblast migration and the negative effect on sarcomere architecture. Taken together, our data suggest that skNAC controls myoblast migration and sarcomere architecture in a calpain-dependent manner.
Biotin-streptavidin detection with a graphene-oxide supported radio-frequency resonator
Authors: Seo Yoon Hyong , Lim Juhwan , Uk Son Sang , Kim Duck-Hwan , Song Insang , Chan Jun Seong
Published: May 2013

The detection of biotin-streptavidin binding was demonstrated by the resonance frequency measurement of a simple resonance circuit using graphene oxide dielectric. The resonance frequency was decreased to the lower frequency range as biotin and streptavidin were bound to the graphene oxide film. Graphene oxide dielectric provides dual advantages including quality-factor enhancement and high affinity for bio sensing. It was revealed that an increase in capacitance of the graphene oxide sheet was mainly responsible for the resonance frequency shift. The sensitivity to the capacitance change in the frequency-based detection technique can enable the advanced biosensing applications using graphene oxide sheet.
Kinetic theory of amyloid fibril templating
Authors: Schmit Jeremy D.
Published: May 2013

The growth of amyloid fibrils requires a disordered or partially unfolded protein to bind to the fibril and adapt the same conformation and alignment established by the fibril template. Since the H-bonds stabilizing the fibril are interchangeable, it is inevitable that H-bonds form between incorrect pairs of amino acids which are either incorporated into the fibril as defects or must be broken before the correct alignment can be found. This process is modeled by mapping the formation and breakage of H-bonds to a one-dimensional random walk. The resulting microscopic model of fibril growth is governed by two timescales: the diffusion time of the monomeric proteins, and the time required for incorrectly bound proteins to unbind from the fibril. The theory predicts that the Arrhenius behavior observed in experiments is due to off-pathway states rather than an on-pathway transition state. The predicted growth rates are in qualitative agreement with experiments on insulin fibril growth rates as a function of protein concentration, denaturant concentration, and temperature. These results suggest a templating mechanism where steric clashes due to a single mis-aligned molecule prevent the binding of additional molecules.
A mapping method for distributive mixing with diffusion: Interplay between chaos and diffusion in time-periodic sine flow
Authors: Schlick Conor P. , Christov Ivan C. , Umbanhowar Paul B. , Ottino Julio M. , Lueptow Richard M.
Published: May 2013

We present an accurate and efficient computational method for solving the advection-diffusion equation in time-periodic chaotic flows. The method uses operator splitting, which allows the advection and diffusion steps to be treated independently. Taking advantage of flow periodicity, the advection step is solved using a mapping method, and diffusion is “added” discretely after each iteration of the advection map. This approach results in the construction of a composite mapping matrix over an entire period of the chaotic advection-diffusion process and provides a natural framework for the analysis of mixing. To test the approach, we consider two-dimensional time-periodic sine flow. By comparing the numerical solutions obtained by our method to reference solutions, we find qualitative agreement for large time steps (structure of concentration profile) and quantitative agreement for small time steps (low error). Further, we study the interplay between mixing through chaotic advection and mixing through diffusion leading to an analytical model for the evolution of the intensity of segregation with time. Additionally, we demonstrate that our operator splitting mapping approach can be readily extended to three dimensions.
The extended wedge method: Atomic force microscope friction calibration for improved tolerance to instrument misalignments, tip offset, and blunt probes
Authors: Khare H. S. , Burris D. L.
Published: May 2013

One of the major challenges in understanding and controlling friction is the difficulty in bridging the length and time scales of macroscale contacts and those of the single asperity interactions they comprise. While the atomic force microscope (AFM) offers a unique ability to probe tribological surfaces in a wear-free single-asperity contact, instrument calibration challenges have limited the usefulness of this technique for quantitative nanotribological studies. A number of lateral force calibration techniques have been proposed and used, but none has gained universal acceptance due to practical considerations, configuration limitations, or sensitivities to unknowable error sources. This paper describes a simple extension of the classic wedge method of AFM lateral force calibration which: (1) allows simultaneous calibration and measurement on any substrate, thus eliminating prior tip damage and confounding effects of instrument setup adjustments; (2) is insensitive to adhesion, PSD cross-talk, transducer/piezo-tube axis misalignment, and shear-center offset; (3) is applicable to integrated tips and colloidal probes; and (4) is generally applicable to any reciprocating friction coefficient measurement. The method was applied to AFM measurements of polished carbon (99.999% graphite) and single crystal MoS2 to demonstrate the technique. Carbon and single crystal MoS2 had friction coefficients of μ = 0.20 ± 0.04 and μ = 0.006 ± 0.001, respectively, against an integrated Si probe. Against a glass colloidal sphere, MoS2 had a friction coefficient of μ = 0.005 ± 0.001. Generally, the measurement uncertainties ranged from 10%–20% and were driven by the effect of actual frictional variation on the calibration rather than calibration error itself (i.e., due to misalignment, tip-offset, or probe radius).
Time-domain reflectometry of high-voltage nonlinear loads with picosecond resolution
Authors: Sharypov K. A. , Shpak V. G. , Shunailov S. A. , Ul'masculov M. R. , Yalandin M. I.
Published: May 2013

The construction and characterization of a measuring module for high voltage time-domain reflectometry with picosecond resolution is presented. The device provides registration of low-distortion reflections from the load at conditions of irregular shape and pronounced instability of an incident probing pulse with amplitude of hundreds of kilovolts and a width/front up to ∼2 ns. This is achieved with registration of differential reflecting signals by using two voltage probes, whose original signals are shifted in time and have a calibrated delay. Specially designed voltage dividers based on coaxial coupled lines with equalized dielectric constant of insulation meet the requirements of voltage probes identity. Reflectometry allows one to study dynamic changes of the loads for a specific time range of ∼10−10 s and faster. An example of reflectometry-based analysis for variations in breakdown development rate of atmospheric discharge gap supplied with the pulses of ∼100-kV amplitude and a front slope of ∼4 × 1014 V/s is presented.
Storing magnetic information in IrMn/MgO/Ta tunnel junctions via field-cooling
Authors: Petti D. , Albisetti E. , Reichlová H. , Gazquez J. , Varela M. , Molina-Ruiz M. , Lopeandía A. F. , Olejník K. , Novák V. , Fina I. , Dkhil B. , Hayakawa J. , Marti X. , Wunderlich J. , Jungwirth T. , Bertacco R.
Published: May 2013

In this paper, we demonstrate that in Ta/MgO/IrMn tunneling junctions, containing no ferromagnetic elements, distinct metastable resistance states can be set by field cooling the devices from above the Néel temperature (TN) along different orientations. Variations of the resistance up to 10% are found upon field cooling in applied fields, in-plane or out-of-plane. Well below TN, these metastable states are insensitive to magnetic fields up to 2 T, thus constituting robust memory states. Our work provides the demonstration of an electrically readable magnetic memory device, which contains no ferromagnetic elements and stores the information in an antiferromagnetic active layer.
Impact of residual carbon on two-dimensional electron gas properties in AlxGa1−xN/GaN heterostructure
Authors: Chen Jr-Tai , Forsberg Urban , Janzén Erik
Published: May 2013

High tuneability of residual carbon doping is developed in a hot-wall metalorganic chemical vapor deposition reactor. Two orders of temperature-tuned carbon concentration, from ∼2 × 1018 cm−3 down to ∼1 × 1016 cm−3, can be effectively controlled in the growth of the GaN buffer layer. Excellent uniformity of two-dimensional electron gas (2DEG) properties in AlxGa1−xN/AlN/GaN heterostructure with very high average carrier density and mobility, 1.1 × 1013 cm−2 and 2035 cm2/V·s, respectively, over 3" semi-insulating SiC substrate is realized with the temperature-tuned carbon doping scheme. Reduction of carbon concentration is evidenced as a key to achieve high 2DEG carrier density and mobility.
On nonlinear physics of shear Alfvén waves
Authors: Chen Liu , Zonca Fulvio
Published: May 2013

Shear Alfvén waves (SAW) are electromagnetic oscillations prevalent in laboratory and nature magnetized plasmas. Due to their anisotropic nature, it is well known that the linear wave propagation and dispersiveness of SAW are fundamentally affected by plasma nonuniformities and magnetic field geometries, such as the existence of continuous spectrum, spectral gaps, and discrete eigenmodes in toroidal plasmas. This work discusses the pure Alfvénic state and demonstrates the crucial roles that finite ion compressibility, non-ideal kinetic effects, and geometry play in breaking it and, thereby, the nonlinear physics of SAW wave-wave interactions.
Simulations of drift resistive ballooning L-mode turbulence in the edge plasma of the DIII-D tokamak
Authors: Cohen B. I. , Umansky M. V. , Nevins W. M. , Makowski M. A. , Boedo J. A. , Rudakov D. L. , McKee G. R. , Yan Z. , Groebner R. J.
Published: May 2013

Results from simulations of electromagnetic drift-resistive ballooning turbulence for tokamak edge turbulence in realistic single-null geometry are reported. The calculations are undertaken with the BOUT three-dimensional fluid code that solves Braginskii-based fluid equations [X. Q. Xu and R. H. Cohen, Contrib. Plasma Phys. 36, 158 (1998)]. The simulation setup models L-mode edge plasma parameters in the actual magnetic geometry of the DIII-D tokamak [J. L. Luxon et al., Fusion Sci. Technol. 48, 807 (2002)]. The computations track the development of drift-resistive ballooning turbulence in the edge region to saturation. Fluctuation amplitudes, fluctuation spectra, and particle and thermal fluxes are compared to experimental data near the outer midplane from Langmuir probe and beam-emission-spectroscopy for a few well-characterized L-mode discharges in DIII-D. The simulations are comprised of a suite of runs in which the physics model is varied to include more fluid fields and physics terms. The simulations yield results for fluctuation amplitudes, correlation lengths, particle and energy fluxes, and diffusivities that agree with measurements within an order of magnitude and within factors of 2 or better for some of the data. The agreement of the simulations with the experimental measurements varies with respect to including more physics in the model equations within the suite of models investigated. The simulations show stabilizing effects of sheared E × B poloidal rotation (imposed zonal flow) and of lower edge electron temperature and density.
Band engineering and growth of tensile strained Ge/(Si)GeSn heterostructures for tunnel field effect transistors
Authors: Wirths S. , Tiedemann A. T. , Ikonic Z. , Harrison P. , Holländer B. , Stoica T. , Mussler G. , Myronov M. , Hartmann J. M. , Grützmacher D. , Buca D. , Mantl S.
Published: May 2013

In this letter, we propose a heterostructure design for tunnel field effect transistors with two low direct bandgap group IV compounds, GeSn and highly tensely strained Ge in combination with ternary SiGeSn alloy. Electronic band calculations show that strained Ge, used as channel, grown on Ge1−xSnx (x > 9%) buffer, as source, becomes a direct bandgap which significantly increases the tunneling probability. The SiGeSn ternaries are well suitable as drain since they offer a large indirect bandgap. The growth of such heterostructures with the desired band alignment is presented. The crystalline quality of the (Si)Ge(Sn) layers is similar to state-of-the-art SiGe layers.
Advanced high-k gate dielectric amorphous LaGdO3 gated metal-oxide-semiconductor devices with sub-nanometer equivalent oxide thickness
Authors: Pavunny S. P. , Misra P. , Thomas R. , Kumar A. , Schubert J. , Scott J. F. , Katiyar R. S.
Published: May 2013

Careful selection of pulsed laser deposition conditions was executed to achieve sub-nanometer EOT (equivalent oxide thickness) in amorphous LaGdO3 based high-k/metal gate stacks. The lowest EOTs attained were ∼5.4 Å and 8.4 Å with and without quantum mechanical correction, respectively. The electrical measurements yielded a high permittivity of 20.5 ± 2.4, a thin bottom interfacial layer of thickness 4.5 ± 1 Å, and interface (cm−2 eV−1) and fixed (cm−2) charge densities of ∼1012. Analysis of temperature dependent leakage currents revealed that gate injection current was dominated by Schottky emission below 1.2 MV/cm and quantum mechanical tunneling above this field. The physical origin of substrate injection was found to be a combination of Schottky emission and trap assisted tunneling.
Microplate-compatible total internal reflection fluorescence microscopy for receptor pharmacology
Authors: Chen Minghan , Zaytseva Natalya V. , Wu Qi , Li Min , Fang Ye
Published: May 2013

We report the use of total internal reflection fluorescence (TIRF) microscopy for analyzing receptor pharmacology and the development of a microplate-compatible TIRF imaging system. Using stably expressed green fluorescence protein tagged β2-adrenergic receptor as the reporter, we found that the activation of different receptors results in distinct kinetic signatures of the TIRF intensity of cells. These TIRF signatures closely resemble the characteristics of their respective label-free dynamic mass redistribution signals in the same cells. This suggests that TIRF in microplate can be used for profiling and screening drugs.
Effects of bulk and interfacial charge accumulation on fill factor in organic solar cells
Authors: Chen Bingbing , Qiao Xianfeng , Liu Chih-Ming , Zhao Chen , Chen Hsiu-Cheng , Wei Kung-Hwa , Hu Bin
Published: May 2013

The effects of charge accumulation on fill factor (FF) are studied by using light intensity-dependent current-voltage and capacitance-voltage measurements based on poly-{bi(dodecyl)thiophene-thieno[3,4-c]pyrrole-4,6-dione}:1(3-methyloxycarbony1)propyl-1-phenyl [6,6] (PBTTPD:PCBM) solar cells. We find that the FF of un-annealed device shows a non-monotonic dependence of light intensity: first an increase and then a decrease with increasing light intensity. This suggests that both bulk charge accumulation and recombination determine the FF before thermal annealing. Furthermore, the morphological enhancement of PBTTPD:PCBM film leads to a monotonic decrease of FF as increasing light intensity. This indicates that only surface charge accumulation plays an important role in the determination of the FF after thermal annealing.
Insight into high-reflectivity AlN/GaN Bragg reflectors with spontaneously formed (Al,Ga)N transient layers at the interfaces
Authors: Gačević Ž. , Eljarrat A. , Peiró F. , Calleja E.
Published: May 2013

This work gives a detailed insight into how the formation of (Al,Ga)N transient layers (TLs) at the interfaces of AlN/GaN Bragg reflectors modifies their structural and optical properties. While abrupt AlN/GaN interfaces are typically characterized with a network of microcracks, those with TLs are characterized with a network of nanocracks. Transmission electron microscopy reveals a strong correlation between strain and the TLs thickness, identifying thus the strain as the driving force for TLs formation. The AlN/GaN intermixing preserves the targeted stopband position (∼410 nm), whereas the peak reflectivity and the stopband width are both reduced, but still significantly high: >90% and >30 nm, respectively. To model their optical properties, a reduced refractive index contrast approximation is used, a novel method which yields an excellent agreement with the experiment.
The effect of nitric oxide anneals on silicon vacancies at and very near the interface of 4H SiC metal oxide semiconducting field effect transistors using electrically detected magnetic resonance
Authors: Cochrane C. J. , Lenahan P. M. , Lelis A. J.
Published: May 2013

We use three electrically detected magnetic resonance (EDMR) approaches to explore nitric oxide (NO) annealing in 4H SiC metal-oxide-semiconductor field-effect transistors (MOSFETs). One approach is sensitive to defects at the interface and those extending into the SiC. Two of these approaches are particularly sensitive to SiC/SiO2 interface defects. They show that NO anneals decrease the EDMR response. Since this and earlier studies indicate the ubiquitous presence of silicon vacancy centers in SiC MOSFETs, our results provide strong circumstantial evidence that these defects play an important role in limiting device performance and that NO anneals are effective in reducing their populations.
Light absorption enhancement in closely packed Ge quantum dots
Authors: Mirabella S. , Cosentino S. , Failla M. , Miritello M. , Nicotra G. , Simone F. , Spinella C. , Franzò G. , Terrasi A.
Published: May 2013

Multilayers of Ge quantum dots (QDs, 3 nm in diameter) embedded in SiO2, separated by SiO2 barrier layer (3, 9, or 20 nm thick), have been synthesized by sputter deposition and characterized by transmission electron microscopy and light absorption spectroscopy. Quantum confinement affects the optical bandgap energy (1.9 eV for QDs, 0.8 eV for bulk Ge); moreover, the absorption probability greatly depends on the QD-QD distance. A strong electronic coupling among Ge QDs is evidenced, with a significant increase of the light absorption efficiency when the QD-QD distance is reduced. These data unveil promising aspects for light harvesting with nanostructures.
Brillouin gain spectrum dependences on temperature and strain in erbium-doped optical fibers with different erbium concentrations
Authors: Ding Mingjie , Hayashi Neisei , Mizuno Yosuke , Nakamura Kentaro
Published: May 2013

Brillouin Stokes power in erbium-doped optical fibers (EDFs) can be potentially controlled by pumping, but no report has been provided on its detailed characterization. In this study, as the first step toward this goal, the Brillouin gain spectra in EDFs with three different erbium concentrations (0.72, 1.20, and 2.28 wtppt) are measured at 1.55 μm without pumping, and the Brillouin frequency shifts (BFSs) and their dependences on strain, temperature, and erbium concentration are fully investigated. In the EDF with 0.72-wtppt concentration, the BFS was 11.42 GHz, and its temperature and strain coefficients were 0.87 MHz/K and 479 MHz/%, respectively.
Quantum Effects on Global Structure of Liquid Water
Authors: Lin Ke , Hu Nai-yin , Zhou Xiao-guo , Liu Shi-lin , Luo Yi
Published: May 2013

The structure difference between light and heavy liquid water has been systematically investigated by high precision Raman spectroscopy over the temperature range of 5–85 °C. Distinct difference between the Raman spectral profiles of two different liquid waters is clearly observed. By analyzing the temperature-dependent Raman spectral contour using global fitting procedure, it is found that the micro-structure of heavy water is more ordered than that of light water at the same temperature, and the structure difference between the light and heavy water decreases with the increase of the temperature. The temperature offset, an indicator for the structure difference, is determined to vary from 28 °C to 18 °C for the low-to-high temperature. It indicates that quantum effect is significantly not only at low temperature, but also at room temperature. The interaction energy among water molecules has also been estimated from van't Hoff's relationship. The detailed structural information should help to develop reliable force fields for molecular modeling of liquid water.
Halogen Bonding or Hydrogen Bonding between 2,2,6,6-Tetramethylpiperidine-noxyl Radical and Trihalomethanes CHX3(X=CI, Br, I)
Authors: Zhao Xiao-ran , Pang Xue , Yan Xiao-qing , Jin Wei-jun
Published: May 2013

The halogen and hydrogen bonding complexes between 2,2,6,6-tetramethylpiperidine-noxyl and trihalomethanes CHX3, (X=CI, Br, I) are simulated by computational quantum chemistry. The molecular electrostatic potentials, geometrical parameters and interaction energy of halogen and hydrogen bonding complexes combined with natural bond orbital analysis are obtained. The results indicate that both halogen and hydrogen bonding interactions obey the order Cl<Br<I, and hydrogen bonding is stronger than the corresponding halogen bonding. So, hydrogen bonding complexes should be dominant in trihalomethanes. However, it is possible that halogen bonding complex is competitive, even preponderant, in triiodomethane due to the similar interaction energy. This work might provide useful information on specific solvent effects as well as for understanding the mechanism of nitroxide radicals as a bioprobe to interact with the halogenated compounds in biological and biochemical fields.