bluuebunny/crossref_metadata_2025 huggingface dataset:
Are seemingly physically similar catchments truly hydrologically similar?
Authors: Oudin Ludovic , Kay Alison , Andréassian Vazken , Perrin Charles
Published: November 2010

This paper discusses the notion of similarity often used in the regionalization studies of hydrological models. We compare two different visions of similarity: the apparent similarity defined on the basis of observable catchment properties, and behavioral similarity judged through the use of hydrological models. These two visions are generally assumed to be merged in regionalization studies: Catchments having apparently similar physical characteristics are assumed to have a similar hydrological behavior. In this paper, we wished to test the validity of this assumption. To this aim, we defined behavioral (hydrological) similarity on the basis of model parameter transferability. Then pools of hydrologically similar catchments are compared with pools of apparently physically similar catchments, as identified on the basis of physiographic catchment descriptors. The overlap between the two pools of similar catchments is analyzed, making it possible to judge the efficiency of the physical similarity measure and to identify hydrologically similar catchments in an ungauged context. The results show that the overlap between the two pools is significant for only 60% of the catchments. For the other catchments, two major reasons were identified as contributing to the lack of overlap: (1) these catchments often have a quite specific hydrological behavior and (2) the role of the underground properties of the catchment on its hydrological behavior was not found to be accurately described by the available physical descriptors, meaning that more relevant catchment descriptors should be sought to better describe the geological and lithological context in hydrological terms.
Modeling belowground water table fluctuations in the Everglades
Authors: Pumo Dario , Tamea Stefania , Noto Leonardo Valerio , Miralles‐Wilhem Fernando , Rodriguez‐Iturbe Ignacio
Published: November 2010

Humid lands, such as riparian zones, peatlands, and unsubmerged wetlands, are considered among the most biologically diverse of all ecosystems, providing a bountiful habitat for a large number of plant and animal species. In such ecosystems, the water table dynamics play a key role in major ecohydrological processes. The aim of the present study is to test with field data a recent analytical model for the estimation of the long‐term probability distribution of the belowground water table position in groundwater‐dependent environments. This model accounts for stochastic rainfall and processes such as infiltration, root water uptake, water flow from/to an external water body, and capillary fluxes. The water table model is tested using field data of groundwater levels recorded in three different sites within the Everglades (Florida, USA). A sensitivity analysis of the model to the soil and vegetation parameters is also carried out. After performing a procedure to determinate appropriate model parameters for the three sites, the steady state probability distribution functions of water table levels predicted by the model are compared to the empirical ones at both the annual and the seasonal time scale. The model is shown capable to reproduce many features of the observed distributions although there exist model predictions which still show some discrepancies with respect to the empirical observations. The potential causes for these discrepancies are also investigated and discussed.
Characteristics of F2‐layer planetary wave–type oscillations in northern middle and high latitudes during 2002 to 2008
Authors: Borries C. , Hoffmann P.
Published: November 2010

A first description of the characteristics of the F2‐layer ionosphere oscillations with periods between 2 and 30 days (so‐called planetary wave–type oscillations, PWTO) is derived using regional maps of total electron content (TEC), covering the northern hemisphere from 50°N to the North Pole. Oscillations forced by quasiperiodic variations of solar signals (e.g., extreme ultraviolet irradiation and solar wind) are identified and separated using wavelet transformation. It is found that up to 50% of the PWTO intensity in the F2‐layer ionosphere occur due to solar variability. The signals that are not obviously related to solar variability are spectrally decomposed to characterize oscillations by their period and wave number. Climatological analyses of the occurring oscillations in TEC reveal similarities to stratospheric planetary waves (PW). These are typical periods of PW, the strongest wave activity during winter and the enhancement of the wave activity at similar latitudes. But there are also major differences to stratospheric PW. In the ionosphere zonal mean oscillations are dominant, stationary waves are not observed, and the dominant periods are shorter than the typical periods of PW in the stratosphere. However, the obtained results are in good agreement with recent numerical modeling results that showed no stationary wave propagation into the F2‐region ionosphere and only fast, short‐period waves that propagate up to the lower thermosphere.
Baroclinic instability and submesoscale eddy formation in weakly stratified oceans under cooling
Authors: Akitomo K.
Published: November 2010

Numerical experiments with a three‐dimensional nonhydrostatic model have been performed to investigate baroclinic instability and submesoscale eddy formation in weakly stratified oceans under cooling. Two types of baroclinic instability can exist in a two‐layered ocean where the convectively formed deep mixed layer overlies the weakly stratified lower layer. One rapidly develops in the mixed layer with short wavelengths (shallow mode), and the other occupies the whole ocean depth with long wavelengths (deep mode). When a background flow is deep, the shallow mode develops first, but the deep mode replaces it in several days. In contrast, only the shallow mode is excited in the mixed layer overlying the strongly stratified layer. The linear stability analysis explains these results well. Despite active cooling, subsequently formed eddies restratify the mixed layer and modify water density over the whole depth. When a background flow is shallow, baroclinic instability is confined to the mixed layer and produces a dipole of surface‐intensified cyclonic eddy and middepth‐intensified anticyclonic eddy, both of which are of submesoscale (∼10 km). The anticyclonic eddy consisting of convectively formed but weakly stratified water moves across the front to ventilate the deep layer, where convection does not reach locally. In this way, density modification extends below the mixed layer. Surface cooling as well as baroclinicity enhances restratification of the mixed layer and density modification at depths by activating submesoscale eddy formation. The results can explain the restratification of the deep mixed layer observed during a cooling season and the origins of submesoscale coherent vortices recently detected in polar oceans.
Dynamics of zonal current variations associated with the Indian Ocean dipole
Authors: Nagura Motoki , McPhaden Michael J.
Published: November 2010

This study examines interannual variability in the equatorial Indian Ocean using observations and a continuously stratified linear long‐wave ocean model driven by European Centre for Medium‐Range Weather Forecasts winds. Our focus is on the relationship between wind stress, zonal velocity, and sea surface height (SSH) in association with the Indian Ocean dipole (IOD). The model correctly simulates the dominant pattern of variability associated with the IOD in which SSH anomalies near the equator tend to tilt zonally in phase with zonal wind forcing. Both observations and the model also show that surface zonal velocity on the equator tends to lead zonal wind stress by about 1 month on interannual time scales. This phasing occurs because velocity anomalies reverse before the wind anomalies reverse during the decay of IOD events. The model simulations indicate that this reversal of velocity earlier than winds is caused by reflected Rossby waves radiating from the eastern boundary. These results have important implications for understanding the evolution of IOD events because of the role of zonal advection in determining interannual variations in equatorial Indian Ocean sea surface temperature anomalies.
The Ste20 kinase misshapen is essential for the invasive behaviour of ovarian epithelial cells in Drosophila
Authors: Cobreros‐Reguera Laura , Fernández‐Miñán Ana , Fernández‐Espartero Cecilia H , López‐Schier Hernán , González‐Reyes Acaimo , Martín‐Bermudo María D
Published: November 2010

Stationary‐to‐migratory transitions of epithelial cells have a key role in development and tumour progression. Border cell migration is a powerful system in which to investigate this transition in living organisms. Here, we identify the Ste20‐like kinase misshapen (msn) as a novel regulator of border‐cell migration in Drosophila. Expression of msn in border cells is independent of the transcription factor slow border cells and of inputs from all pathways that are known to control border‐cell migration. The msn gene functions to modulate the levels and/or distribution of Drosophila E‐cadherin to promote the invasive migratory behaviour of border cells.
Darwin at the edge of the visible universe
Authors: Morris Simon Conway
Published: November 2010

Simon Conway Morris marvels at the perfection of sensory organs: shaped by eons of evolution, they can detect a single photon or an individual molecule. Only scientific instruments are able to reach beyond the limits of nature's detectors.
Is Huntington disease a developmental disorder?
Authors: Humbert Sandrine
Published: November 2010

The recently discovered roles of huntingtin in non‐differentiated cells indicate that it is a key molecule in brain development. Humbert argues that the haploinsufficiency of wild‐type huntingtin in Huntington disease might lead to various cellular alterations well before the onset of symptoms and ultimately cause disease.
Unconjugated Bilirubin Contributes to Early Inflammation and Edema after Intracerebral Hemorrhage
Authors: Loftspring Matthew C , Johnson Holly L , Feng Rui , Johnson Aaron J , Clark Joseph F
Published: November 2010

Intracerebral hemorrhage (ICH) is a stroke subtype with significant mortality and morbidity. The role of unconjugated bilirubin (UBR) in ICH brain injury is not well understood. Therefore, we studied the effects of UBR on brain injury markers and inflammation, as well as mechanisms involved therein. We induced ICH in mice by infusion of autologous whole blood with vehicle (dimethyl sulfoxide) or UBR. We found that UBR led to an increase in edema ( P0.05), but a decrease in nitrate/nitrite formation (7.0±0.40 nmol/mg versus 5.2±0.70 nmol/mg protein, P0.05) and no change in protein carbonyls. Unconjugated bilirubin was also associated with an increase in neutrophil infiltration compared with ICH alone, as determined by both immunofluorescence and flow cytometry (36%±3.2% versus 53%±1.3% of CD45+ cells, P0.05). In contrast, we observed reduced perihematomal microglia immunoreactivity in animals receiving UBR ( P0.05). Using in vitro techniques, we show neutrophil activation by UBR and also show that protein kinase C participates in this signaling pathway. Finally, we found that UBR was associated with an increased expression of the leukocyte adhesion molecule intercellular adhesion molecule-1. Our results suggest that UBR possesses complex immune-modulatory and antioxidant effects.
Iron Toxicity in Mice with Collagenase-Induced Intracerebral Hemorrhage
Authors: Wu He , Wu Tao , Xu Xueying , Wang Jessica , Wang Jian
Published: November 2010

Intracerebral hemorrhage (ICH) is a devastating form of stroke. In this study, we examined the efficacy of deferoxamine (DFX), an iron chelator, after collagenase-induced ICH in 12-month-old mice. Intracerebral hemorrhage was induced by intrastriatal injection of collagenase. Deferoxamine (200 mg/kg, intraperitoneal) or vehicle was administrated 6 hours after ICH and then every 12 hours for up to 3 days. Neurologic deficits were examined on days 1 and 3 after ICH. Mice were killed after 1 or 3 days of DFX treatment for examination of iron deposition, neuronal death, oxidative stress, microglia/astrocyte activation, neutrophil infiltration, brain injury volume, and brain edema and swelling. Collagenase-induced ICH resulted in iron overload in the perihematomal region on day 3. Systemic administration of DFX decreased iron accumulation and neuronal death, attenuated production of reactive oxygen species, and reduced microglial activation and neutrophil infiltration without affecting astrocytes. Although DFX did not reduce brain injury volume, edema, or swelling, it improved neurologic function. Results of our study indicate that iron toxicity contributes to collagenase-induced hemorrhagic brain injury and that reducing iron accumulation can reduce neuronal death and modestly improve functional outcome after ICH in mice.
Quantitation of 55 Common Human Plasma Proteins in Healthy Young Adults and Correlation with Body Mass Index and Dietary Patterns
Authors: Garcia-Bailo Bibiana , Brenner Darren , Nielsen Daiva , Lee Hyeon-Joo , Borchers Christoph , Badawi Alaa , Karmali Mohamed , El-Sohemy Ahmed
Published: November 2010

Plasma biomarkers are a useful tool for monitoring dietary exposures and the development of chronic disease. Measuring multiple biomarkers at once provides a more complete characterization of phenotype than measuring single markers. Certain dietary patterns have been associated with increased risk of obesity. Adhering to a ‘Western’ dietary pattern, characterized by high consumption of meat products and low fruit and vegetable consumption, may put individuals at a higher risk of becoming overweight or obese than a ‘Prudent’ or an ‘Eastern’ dietary pattern. A novel mass spectrometry-based multiple reaction monitoring (MRM) proteomics assay was used to quantitate 55 common plasma proteins that have been linked to chronic disease. We measured the concentrations of these proteins in 1088 participants of the Toronto Nutrigenomics and Health (TNH) study, an ethnically diverse population of young adults. Our goals were: 1) to explore clustering patterns within the protein panel; 2) to investigate whether protein cluster scores differ between normal weight (BMI<25) and overweight/obese (BMI≥25) individuals; and 3) to determine whether protein cluster scores differ between ‘Prudent’, ‘Western’ and ‘Eastern’ dietary patterns. Four principal components (PC) account for most of the variability in the protein profiles, with eigenvalues ranging from 22.3 (PC 1) to 2.9 (PC 4). Significant differences were observed in the average loading scores between normal weight and overweight/obese individuals for PCs 2 and 3. In particular, PC3 scores were significantly higher among those with BMI≥25. Linear regression adjusted for age, sex, ethnicity, physical activity and total caloric intake showed significant associations between dietary intake and PCs 1, 2 and 3. PCs 1 and 3 were positively associated with the ‘Western’ dietary pattern, and PC1 was also inversely associated with the ‘Eastern’ pattern. PC 2 was positively associated with the ‘Eastern’ dietary pattern. These results suggest a relationship between the examined panel of protein biomarkers, BMI and certain dietary patterns. Future analyses will assess the biological relevance of these results.
Antioxidant response of overwintering conifers suggest species specific strategies for coping with excess excitation energy
Authors: Hughes Kim , Verhoeven Amy , Kokula Alex
Published: November 2010

Background/Question/Methods:

Evergreen plants, growing in seasonally cold environments, must cope with a severe imbalance between light absorption and its utilization, as low temperatures during winter inhibit photosynthetic carbon reduction. In such conditions photoprotective mechanisms are critical, including the leaf antioxidant systems of plants. In a previous study examining Taxus cuspidata, we found significant increases in the enzyme glutathione reductase (GR) and the metabolite glutathione (GSH) during winter, but no increases in the enzymes superoxide dismutase, ascorbate peroxidase (APX) or the metabolite ascorbate (ASC). These results led to the hypothesis that GR and GSH serve an important role during winter stress that was separate form their role in the ascorbate glutathione cycle. The goal of this study was to examine the seasonal response of several species of conifers in order to determine if the differences in the antioxidant response observed in Taxus would occur generally in conifers during winter, or if there are species specific effects. We collected needle tissue in summer and winter from three conifer species: eastern white pine (Pinus strobus L.), balsam fir [Abies balsamea (L.) P. Mill], and white cedar (Thuga occidentalis L.). We analyzed the activity of both GR and APX and the amount of GSH and ASC.

Results/Conclusions:

Our results demonstrated significant increases in the antioxidant enzyme GR in all species in response to winter stress. The antioxidant enzyme APX showed significant winter increases in two species (pine and cedar) but not the third (fir). Preliminary results of the antioxidant metabolites glutathione and ascorbate show similar results. Our data suggest that the different species examined utilize different strategies for coping with excess excitation energy during winter. Pine and cedar apparently boost their overall antioxidant enzyme capacity and their utilization of the ascorbate glutathione cycle. Balsam fir shows a similar response to Taxus cuspidata, where glutathione reductase activity is significantly increased but ascorbate peroxidase activity is not. These results suggest a role for reduced glutathione in winter-stressed fir that is independent of its role in the ascorbate glutathione cycle.
Mechanisms Of Inhibition Of Cigarette Smoke Genotoxicity And Carcinogenicity
Authors: Balansky Roumen , D'Agostini Francesco , Izzotti Alberto , Kalpakam P , Steele Vernon , De Flora Silvio
Published: November 2010

Epidemiological studies have demonstrated that it is possible to prevent lung cancer and other smoke-related diseases by avoiding exposures to tobacco smoke. A complementary strategy is chemoprevention, which is based on the administration of dietary and pharmacological agents, which is addressed to (a) addicted active smokers, who are unable to quit smoking, (b) ex-smokers, who are still at risk for several years, and (c) involuntary smokers, including passively exposed individuals as well as transplacentally exposed individuals. The biological effects of cigarette smoke (CS) as a complex mixture, either mainstream (MCS) or sidestream (SCS) or environmental (ECS), have been poorly explored. We showed that MCS and ECS induce a broad variety of alterations of intermediate biomarkers in animal models, including adducts to nuclear DNA and mtDNA, oxidatively generated DNA damage, proliferation, apoptosis, alterations of oncogenes and tumor suppressor genes, multigene expression, microRNA and proteome profiles as well as cytogenetic damage in the respiratory tract, bone marrow and peripheral blood. CS-altered end-points were variously modulated by chemopreventive agents of natural or pharmacological origin, such as N-acetyl-L-cysteine (NAC), 1,2-dithiole-3-thione, oltipraz, 5,6-benzoflavone, phenethyl isothiocyanate (PEITC), indole-3-carbinol, sulindac, and budesonide. Combinations of agents were also assayed. Since it is difficult to assess the efficacy of chemopreventives in clinical trials, it is essential to understand the mechanisms by which certain agents are expected to prevent smoke-related cancer. Preclinical studies are also useful to demonstrate the potential efficacy of chemopreventive agents. Unfortunately, until recently a suitable animal model for evaluating CS carcinogenicity and its chemoprevention was not available. We demonstrated that ECS and especially MCS become potently carcinogenic when exposure of mice starts at birth, as shown by very short latency times, high incidence and multiplicity of benign lung tumors, early occurrence of malignant lung tumors, and lesions in other organs. This mouse model was successfully used to demonstrate the ability of NAC, PEITC, and budesonide to prevent smoke-induced lung cancer, according to protocols mimicking the situation either in current smokers or in ex-smokers. Other dietary or pharmacological agents, including curcumin, anthocyanins, myo-inositol, SAHA, bexarotene and pioglitazone, are now under study. NAC was even successful to prevent lung cancer induced by MCS after birth when it was administered during the prenatal life. Therefore, it is now possible to investigate in vivo not only alterations of intermediate biomarkers but also the modulation of CS carcinogenesis by chemopreventive agents working with different mechanisms.
Very low dose isotretinoin is effective in controlling seborrhea
Authors: Geißler Sabine E. , Michelsen Silke , Plewig Gerd
Published: November 2010

Background: Excessive seborrhea, coarse‐pored skin, minimal acne and oily scalp hair comprise a well‐known clinical entity. It causes considerable concern, has social impact, and affects the quality of life in some individuals. Some patients seek treatment for seborrhea. No effective topical sebosuppressive medication is available. Oral isotretinoin is the only remedy for men. In women, oral isotretinoin is the most effective remedy, followed by antiandrogens.

Patients and methods: Eleven patients in three groups were treated for 6 months with very low dose isotretinoin. The influence on seborrhea was measured during oral treatment with 5 mg/d, 2.5 mg/d, or 2.5 mg 3× weekly.

Results: Sebum production, measured with Sebutape®, was reduced by up to 64 %. Acne lesions regressed by as much as 84 %. Follicular filaments were reduced by 66 %. Microcomedones were reduced on average up to 86 %. Quantitative bacteriology showed a reduction of Propionibacterium acnes but no increase of Staphylococcus epidermidis. Biopsies revealed a 51 % reduction in sebaceous gland size. With Bentonite™, a reduction of lipids was demonstrated with 2.5 and 5 mg isotretinoin/d but not with 2.5 mg 3× weekly. There was a shift within the lipid fractions: triglycerides dominated, followed by squalenes and free fatty acids.

Conclusions: Good results were achieved in all patients. The small number of patients did not permit a statistical analysis of the three isotretinoin doses studied, but there was a tendency toward better results with the two higher doses.
Native specific activity of glutathione peroxidase (GPx‐1), phospholipid hydroperoxide glutathione peroxidase (PHGPx) and glutathione reductase (GR) does not differ between normo‐ and hypomotile human sperm samples
Authors: Tramer Federica , Caponecchia Luisa , Sgrò Paolo , Martinelli Monica , Sandri Gabriella , Panfili Enrico , Lenzi Andrea , Gandini Loredana
Published: November 2010

Glutathione‐dependent selenoenzymes in human spermatozoa are responsible for a generalized protection against reactive oxygen species (ROS) as well as some other metabolic and structural regulation during spermiogenesis and sperm cell maturation. Glutathione peroxidase (GPx‐1), phospholipid hydroperoxide glutathione peroxidase (GPx‐4 or PHGPx) and glutathione reductase (GR) native specific activities have been studied in human Percoll‐purified spermatozoa from healthy fertile subjects and asthenozoospermic patients. The mean values obtained for the three enzymes in normal specimens are 1.52 ± 0.90 mU/106 sperm cells (PHGPx), 4.26 ± 1.73 mU/106 sperm cells (GPx‐1) and 1.95 mU/106 sperm cells (GR). No statistically significant differences for any of the three enzymes were encountered between these values and those of asthenozoospermic patients. These results are discussed and compared with recent literature data on both rescued and native PHGPx specific activity in human spermatozoa, as well as with data obtained for GPx in human seminal plasma.
Medieval Japan: Taking the Middle Ages Outside Europe
Authors: Keirstead Tom
Published: November 2010

What does it mean to claim that a nation has had a medieval period? And, given how closely associated the concept is with a specifically European history, how might a non‐Western country claim the period for its own past? This article will look at what historians have labeled Japan's Middle Ages in order to investigate these issues. We will consider how Japan came to have a medieval period, examine what historians regard as its key features, and investigate some problems associated with taking the concept of the Middle Ages to Japan.
Detection and monitoring of insect resistance to transgenic Bt crops
Authors: HUANG FANGNENG
Published: November 2010

Abstract
Transgenic crops expressing Bacillus thuringiensis (Bt) endotoxins have become one of the most important tools for managing corn and cotton insect pests in the US and other countries. The widespread adoption of transgenic Bt crops could place a high degree of selection pressure on the target insect populations and accelerate development of resistance, raising concerns about the long‐term durability of Bt plants as an effective pest management tool. Conservation of Bt susceptibility in insects has become one of the most active research areas in modern agriculture. One of the key factors for a successful Bt resistance management plan is to have a cost‐effective monitoring system that can provide information on: (i) the initial Bt resistance allele frequencies at low levels in field insect populations; and (ii) early shifts in Bt resistance allele frequencies so that proactive measures for managing resistance can be deployed well before field control failures. Developing such a monitoring program has been difficult because: (i) resistance traits that occur at very low frequencies are hard to detect; (ii) many factors affect the sensitivity and accuracy of a Bt resistance monitoring program; and (iii) monitoring resistance is costly. Several novel methods for detecting Bt resistance alleles developed during the last decade have made a cost‐effective monitoring system possible. Future studies should focus on how to improve and standardize the methodologies for insect sampling and Bt resistance detection.
Alopecia areata im Tiermodell – Neue Einblicke in Pathogenese und Therapie einer T‐Zell‐vermittelten Autoimmunerkrankung
Authors: Freyschmidt‐Paul Pia , Happle Rudolf , Hoffmann Rolf
Published: November 2010

Die Möglichkeiten zur Erforschung der Pathogenese der Alopecia areata und zur Entwicklung neuer Therapieansätze sind beim Menschen aus ethischen Gründen begrenzt. Daher ist die Entwicklung geeigneter Tiermodelle für die Alopecia areata sinnvoll. Mit der Dundee experimental bald rat (DEBR) und der C3H/HeJ‐Maus stehen mittlerweile zwei gut charakterisierte Tiermodelle der Alopecia areata zur Verfügung, an denen Studien zur Genetik, Pathogenese und Therapie der Alopecia areata durchgeführt werden können. Ein besonderer Vorteil der C3H/HeJ‐Maus besteht in der Möglichkeit, die Alopecia areata durch Hauttransplantation experimentell zu induzieren, und dann den Einfluß verschiedener Faktoren auf den Verlauf der Erkrankung zu untersuchen. Durch Untersuchungen an der C3H/HeJ‐Maus und der DEBR konnte die T‐Zell‐vermittelte Autoimmunpathogenese der Alopecia areata bestätigt werden, und es ließen sich einzelne Mechanismen dieser T‐Zell‐vermittelten Immunreaktion analysieren. Ausgehend von diesen Erkenntnissen ergeben sich verschiedene neue Optionen für die Therapie der Alopecia areata wie die Blockade des Lymphozytenhomings durch Applikation eines monoklonalen Anti‐CD44v10‐Antikörpers oder die Hemmung der T‐Zell‐Aktivierung durch Blockade kostimulatorischer Moleküle. Therapeutische Studien am Maus‐ und Rattenmodell sprechen dafür, daß die topische Applikation von Tacrolimus zur Behandlung der Alopecia areata des Menschen im Prinzip geeignet ist, sofern sich die Galenik verbessern läßt. Zukünftige Untersuchungen zum Wirkmechanismus des allergischen Kontaktekzems in der Behandlung der Alopecia areata sollen dazu dienen, eine auf dieser Behandlung aufbauende, spezifischere Therapie zu entwickeln.
Study of the transport parameters of cloud lightning plasmas
Authors: Chang Z. S. , Zhao N. , Yuan P.
Published: November 2010

Three spectra of cloud lightning have been acquired in Tibet (China) using a slitless grating spectrograph. The electrical conductivity, the electron thermal conductivity, and the electron thermal diffusivity of the cloud lightning, for the first time, are calculated by applying the transport theory of air plasma. In addition, we investigate the change behaviors of parameters (the temperature, the electron density, the electrical conductivity, the electron thermal conductivity, and the electron thermal diffusivity) in one of the cloud lightning channels. The result shows that these parameters decrease slightly along developing direction of the cloud lightning channel. Moreover, they represent similar sudden change behavior in tortuous positions and the branch of the cloud lightning channel.
Chimeras in a network of three oscillator populations with varying network topology
Authors: Martens Erik A.
Published: November 2010

We study a network of three populations of coupled phase oscillators with identical frequencies. The populations interact nonlocally, in the sense that all oscillators are coupled to one another, but more weakly to those in neighboring populations than to those in their own population. Using this system as a model system, we discuss for the first time the influence of network topology on the existence of so-called chimera states. In this context, the network with three populations represents an interesting case because the populations may either be connected as a triangle, or as a chain, thereby representing the simplest discrete network of either a ring or a line segment of oscillator populations. We introduce a special parameter that allows us to study the effect of breaking the triangular network structure, and to vary the network symmetry continuously such that it becomes more and more chain-like. By showing that chimera states only exist for a bounded set of parameter values, we demonstrate that their existence depends strongly on the underlying network structures, and conclude that chimeras exist on networks with a chain-like character.
Entropic noise-induced nonequilibrium transition
Authors: Mondal Debasish , Das Moupriya , Ray Deb Shankar
Published: November 2010

We consider a system of Brownian particles confined in a two-dimensional bilobal enclosure. Varying cross-section of the confinement results in an effective entropic potential in reduced dimension. We show that the system may undergo an entropic noise-induced transition when the shape of the stationary probability density changes qualitatively from bimodal to trimodal type under the influence of a multiplicative noise.
Effects of Mg concentration on solubility and chemical state of N in N-doped MgZnO alloy
Authors: Gao Lili , Yao Bin , Liu Bo , Liu Li , Yang Tong , Liu Bingbing , Shen Dezhen
Published: November 2010

Solubility and chemical state of N in an N-doped MgxZn1–xO film were studied by using Raman and x-ray photoelectron spectroscopy. Three anomalous Raman peaks are observed at 272, 580, and 642 cm−1, respectively, and are demonstrated to be only related to substitution of N for O site (NO) but not to substitution of N2 for O site (N2)O. The solubility of the NO is dominated by Mg concentration and chemical potentials of N and O in growth condition. The chemical state of the N can change from coexistence of (N2)O and NO to single (N2)O with increasing Mg concentration.
Effects of counterion size on the attraction between similarly charged surfaces
Authors: Zelko Jasna , Iglič Aleš , Kralj-Iglič Veronika , Kumar P. B. Sunil
Published: November 2010

Interaction between similarly charged surfaces can be attractive at high electrostatic coupling constants Ξ = lBZ2/μGC, where lB is the Bjerrum length, μGC the Gouy–Chapman length, and Z the valency of counterions. While this effect has been studied previously in detail, as a function of surface charge density and valency of the pointlike counterions, much less is known about the effect of counterion size. We apply the Wang–Landau sampling Monte Carlo (MC) simulation method to compute the free energy F as a function of the scaled distance between the plates \documentclass[12pt]{minimal}\begin{document}${\widetilde{D}}=D/\mu _{\rm GC}$\end{document}D̃=D/μ GC for a range of Ξ and scaled counterion radii \documentclass[12pt]{minimal}\begin{document}${\widetilde{R}}=R/\mu _{\rm GC}$\end{document}R̃=R/μ GC . We find that for large Ξ and small ion radius, there is a global equilibrium distance \documentclass[12pt]{minimal}\begin{document}$ {\widetilde{D}}= {\widetilde{D}}_{\rm eq} =2(1+{\widetilde{R}})$\end{document}D̃=D̃ eq =2(1+R̃), correctly giving the expected value at the point counterion limit. With increasing \documentclass[12pt]{minimal}\begin{document}${\widetilde{R}}$\end{document}R̃ the global minimum in \documentclass[12pt]{minimal}\begin{document}$F({\widetilde{D}})$\end{document}F(D̃) changes to a metastable state and finally this minimum vanishes when \documentclass[12pt]{minimal}\begin{document}${\widetilde{R}}$\end{document}R̃ reaches a critical value, which depends on Ξ. We present a state diagram indicating approximate boundaries between these three regimes. The Wang–Landau MC method, as it is applied here, offers a possibility to study a wide spectrum of extended problems, which cannot be treated by the use of contact value theorem.
Origin of suppressed polarization in BiFeO3 films
Authors: Park J. W. , Baek S. H. , Wu P. , Winchester B. , Nelson C. T. , Pan X. Q. , Chen L. Q. , Tybell T. , Eom C. B.
Published: November 2010

We have studied the origin of suppressed remanent polarization in 4-variant BiFeO3 by correlating microscopic observations of ferroelectric/ferroelastic domain structures and ferroelectric measurements of (001) epitaxial BiFeO3 thin films with 2- and 4-ferroelastic domain variants. Piezoelectric force microscopy revealed that domain wall pinning was the cause of the reduced polarization observed in 4-variant BiFeO3. Using repetitive switching, the unswitched domains were completely switched and the remanent polarization reached a value comparable to 2-variant BiFeO3. These results demonstrate that control of ferroelastic domains in rhombohedral systems is necessary in order to obtain high performance and reliable ferroelectric and magnetoelectric devices.
High-pressure vibrational properties of polyethylene
Authors: Fontana Luca , Santoro Mario , Bini Roberto , Vinh Diep Q. , Scandolo Sandro
Published: November 2010

The pressure evolution of the vibrational spectrum of polyethylene was investigated up to 50 GPa along different isotherms by Fourier-transform infrared and Raman spectroscopy and at 0 K by density-functional theory calculations. The infrared data allow for the detection of the orthorhombic Pnam to monoclinic P21/m phase transition which is characterized by a strong hysteresis both on compression and decompression experiments. However, an upper and lower boundary for the transition pressure are identified. An even more pronounced hysteresis is observed for the higher-pressure transition to the monoclinic A2/m phase. The hysteresis does not allow in this case the determination of a well defined P-T transition line. The ambient structural properties of polyethylene are fully recovered after compression/decompression cycles indicating that the polymer is structurally and chemically stable up to 50 GPa. A phase diagram of polyethylene up to 50 GPa and 650 K is proposed. Analysis of the pressure evolution of the Davydov splittings and of the anomalous intensification with pressure of the IR active wagging mode provides insight about the nature of the intermolecular interactions in crystalline polyethylene.
Classical theory of two-dimensional time-domain terahertz spectroscopy
Authors: Hattori Toshiaki
Published: November 2010

A general theoretical framework of two-dimensional time-domain second-order and third-order terahertz spectroscopy has been presented. The theoretical treatment is based on a classical and phenomenological model with weak nonlinearities. Three types of nonlinearity sources, anharmonicity, nonlinear coupling, and nonlinear damping, were considered. The second-order THz spectroscopy has an exact correspondence to fifth-order off-resonance Raman spectroscopy, and it has been shown that the present treatment gives exactly the same results as of the quantum mechanical theory under the weak nonlinearity condition. General expressions for the nonlinear signal have been obtained for a single-mode system, and numerical calculations for delta-function incident terahertz pulses were shown. For the third-order signal, two-level systems were also considered for comparison. Contributions of two types of incident pulse sequences have been studied separately in the third-order signals. Profiles of the two-dimensional signals were found to depend on the origin and order of the nonlinearity and also on the pulse sequence. The results of the present study show that the two-dimensional signal features of second- and third-order nonlinear terahertz spectroscopy can clarify the nature of the system which is not accessible using linear spectroscopy.
The glass transition behaviors of low-density amorphous ice films with different thicknesses
Authors: He Cheng , Zhang Wenxue , Li Yu
Published: November 2010

The glass transition behaviors of amorphous ice with different thicknesses are studied by determining the heat capacity of low-density amorphous ice without crystallization using first principle molecular dynamics (FP-MD) and classical MD methods. The behaviors are also studied by analyzing hydrogen-bond network, the radial distribution functions, and relationship between hydrogen bond and electronic structures. It is found that the glass transition temperature (Tg) in the range of 90 K < T < 100 K for 4 nm amorphous ice film by FP-MD method, and 120 K < Tg < 130 K for 8 nm amorphous ice film by MD method. Meanwhile, Tg decreases with the decreasing thickness of amorphous ice film, which is also validated by the theoretical model.
Effects of oxygen vacancies and grain sizes on the dielectric response of BaTiO3
Authors: Choi Youn-Kyu , Hoshina Takuya , Takeda Hiroaki , Teranishi Takeshi , Tsurumi Takaaki
Published: November 2010

The effects of grain size and oxygen vacancies on the dielectric responses of BaTiO3 ceramics were investigated using wideband dielectric spectroscopy. Both dipole and ionic polarizations were enhanced by the reduction in grain size down to 2.5 μm. The annealing in low oxygen partial pressure markedly suppressed the dipole polarization possibly due to the domain-wall clamping by oxygen vacancies. To explain the dielectric response of BaTiO3 ceramics, a complex structure including gradient lattice strain layers (GLSL) were proposed as a model of 90° domain structure.
Future direction of direct writing
Authors: Kim Nam-Soo , Han Kenneth N.
Published: November 2010

Direct write technology using special inks consisting of finely dispersed metal nanoparticles in liquid is receiving an undivided attention in recent years for its wide range of applicability in modern electronic industry. The application of this technology covers radio frequency identification-tag (RFID-tag), flexible-electronics, organic light emitting diodes (OLED) display, e-paper, antenna, bumpers used in flip-chip, underfilling, frit, miniresistance applications and biological uses, artificial dental applications and many more. In this paper, the authors have reviewed various direct write technologies on the market and discussed their advantages and shortfalls. Emphasis has given on microdispensing deposition write (MDDW), maskless mesoscale materials deposition (M3D), and ink-jet technologies. All of these technologies allow printing various patterns without employing a mask or a resist with an enhanced speed with the aid of computer. MDDW and M3D are capable of drawing patterns in three-dimension and MDDW, in particular, is capable of writing nanoinks with high viscosity. However, it is still far away for direct write to be fully implemented in the commercial arena. One of the hurdles to overcome is in manufacturing conductive inks which are chemically and physically stable, capable of drawing patterns with acceptable conductivity, and also capable of drawing patterns with acceptable adhesiveness with the substrates. The authors have briefly discussed problems involved in manufacturing nanometal inks to be used in various writing devices. There are numerous factors to be considered in manufacturing such inks. They are reducing agents, concentrations, oxidation, compact ability allowing good conductivity, and stability in suspension.
Reliability of gravure offset printing under various printing conditions
Authors: Lee Taik-Min , Noh Jae-Ho , Kim Inyoung , Kim Dong-Soo , Chun Sangki
Published: November 2010

This paper focuses on the reliability of gravure offset printing and presents a mechanism on how the width of the printed line increases on repeated printings. Of the various printing process parameters, such as the resting times between doctoring, off, and set, printing velocity, printing pressure, and so forth, we investigated the effects of printing velocity, printing pressure, and blanket’s thickness on the reliability of gravure offset printing. As the printing velocity increases, the reliability of gravure offset printing also increases. This is because the actual contact time between ink and blanket decreases, resulting in less solvent absorption into the blanket. Printing pressure does not have much influence on reliability. Even though some change was observed, it was within the range of experimental error. Under sufficient printing pressure, this observation implies that the more important factor as regards the absorption model is time rather than pressure. As the thickness of the blanket increases, the reliability also increases. In the case of a thin blanket, in particular, the reliability of gravure offset printing is sensitive to changes in thickness.
Decomposition results for Gram matrix determinants
Authors: Banica Teodor , Curran Stephen
Published: November 2010

We study the Gram matrix determinants for the groups Sn, On, Bn, Hn, for their free versions \documentclass[12pt]{minimal}\begin{document}$S_n^+,O_n^+,B_n^+,H_n^+$\end{document}Sn+,On+,Bn+,Hn+, and for the half-liberated versions \documentclass[12pt]{minimal}\begin{document}$O_n^*,H_n^*$\end{document}On*,Hn*. We first collect all the known computations of such determinants, along with complete and simplified proofs, and with generalizations where needed. We conjecture that all these determinants decompose as D = ∏πφ(π), with product over all associated partitions.
Rheological properties of Ag suspended fluid for inkjet printing
Authors: Park B. J. , Park B. O. , Ryu B. H. , Choi Y. M. , Kwon K. S. , Choi H. J.
Published: November 2010

Rheological characterization of inks for the inkjet printing application has been considered to be essential with dissemination of applying the inkjet printing technology into many related industries. In this study, the high concentrated Ag suspension was prepared using poly(acrylic acid) as both a polyelectrolyte and a polymeric dispersant, and rheological properties of the suspension such as shear stress, shear viscosity, and dynamic moduli were examined using a rotational rheometer. The difference of rheological properties was investigated with different concentrations of the polyelectrolyte. The shear thinning effects and yield behavior of suspension were analyzed using rheological constitutive equations of state.
A simulation and experimental study on packing of nanoinks to attain better conductivity
Authors: Amert Anthony K. , Oh Dong-Hoon , Kim Nam-Soo
Published: November 2010

A simulation and experimental study on the packing of nanoinks has been carried out. Simulation predicted that the packing of two different sized monodispersed colloids would results in a more densely packed structure than a single sized monodispered colloid alone. The simulated results were confirmed by conducting experiments with two different sized-monodispersed silver colloids. A binary sized ink was printed in a rectangular pattern using a direct write method system and then the final pattern was sintered. The pattern was confirmed to be highly conductive and the final conductivity obtained from this pattern gave 47% of the bulk conductivity of silver.
The effect of reduction atmospheres on the sintering behaviors of inkjet-printed Cu interconnectors
Authors: Kim Inyoung , Kim Jongryoul
Published: November 2010

In order to overcome the serious problems posed by Cu ink, which include the strong tendency to the oxidation of Cu nanopowders, various reduction atmospheres were investigated. As a result, a resistivity of ∼4 μΩ cm was achieved in the Cu interconnectors sintered at 200 °C with a gaseous mixture of formic acid (HCOOH) and alcohol. As regards this sample, micrographs show the facet boundaries and an average grain size of ∼300 nm. The use of formic acid was an effective way to decrease the sintering temperature to 150 °C, at which temperature the resistivity was ∼72 μΩ cm. This low temperature sintering and microstructural densification was due to the decomposition of capping molecules and the reduction in Cu oxide by formic acid.
Friction effect on the rotation of bichromal ball in a monolayer rotating ball display
Authors: Lee Youngwoo , Lee Sangmoon , Kwak Jeong-Bok , Kim Sangjin , Cha Hye-Yeon , Lee Choong Hee , Lee Chong Seo , Lee Hwan-Soo
Published: November 2010

A rotating ball display was tested with a thin monolayer sheet. An oil cavity was formed in the shape of a spheroid in a thin elastomer sheet. The rotation of a bichromal ball was investigated from the point of rotation time from one color to the other color. Bichromal balls were under friction during rotation. The friction caused an abnormal change in the rotation time. The rotation time of the elastomer sheet was compared with that of a microcup rotating ball display. The friction explained the difference of rotation time variation between the elastomer sheet display and the microcup display.
Thermal stability of Si-doped InGaN multiple-quantum wells for high efficiency light emitting diodes
Authors: Lee Sung-Nam , Kim Jihoon , Kim Kyoung-Kook , Kim Hyunsoo , Kim Han-Ki
Published: November 2010

Excitation power dependent photoluminescence (PL) spectroscopy was employed to determine the thermal degradation of InGaN quantum wells (QWs) structure with different Si doping in well region. At a low excitation power density, PL intensity of undoped InGaN well was significantly decreased, while those of interfacial and full Si-doped InGaN well were slightly reduced by rapid thermal annealing (RTA) process. However, PL measurement with high excitation power density showed that PL intensities of InGaN QWs regardless of Si doping were almost similar with/without RTA process. In addition, x-ray diffraction results indicated that Si-doping in well could improve the interfacial quality of InGaN QWs. Therefore, we suggest that Si doping suppress the generation of nonradiative recombination centers by thermal degradation at weaker localization states which could be easily filled by low excitation carriers.
An ab initio study of the elastic behavior of single crystal group (IV) diborides at elevated temperatures
Authors: Gonzales Manny , Chessa Jack , Ramana C. V.
Published: November 2010

We report on an ab initio molecular dynamics study of the lattice parameters, thermal expansion coefficients, and elastic constants of ZrB2, TiB2, and HfB2 ceramics at ultrahigh temperatures (up to 2200 K). Equilibrium lattice parameters of the ceramics are determined at finite temperatures. A finite strain method is used to extract the stiffness tensor of the ceramics. The results obtained for ZrB2 and TiB2 agree well with experimental results reported in the literature. Our work demonstrate that accurate properties may be obtained from a statistical averaging of the lattice parameters alone neglecting phonon interactions.