bluuebunny/crossref_metadata_2025 huggingface dataset:
Echocardiographic and morphological evaluation of the right heart after closure of atrial septal defects
Authors: Sun Pin , Wang Zhi-Bin , Xu Chuan-Jin , Yang Su-Min , Jiang Lei
Published: October 2008

Objective

To evaluate echocardiographically the function and morphology of the right heart subsequent to transcatheter closure of atrial septal defects.

Methods

We performed echocardiographic studies in 73 patients undergoing transcatheter closure of atrial septal defects 1 day prior to closure, and then 3 days and 3 months after closure. We calculated the antero-posterior diameter of the right ventricle, the transverse diameter and length of the right atrium, the pulmonary arterial pressure, and the velocities of systolic movement and early and late diastolic movement of the basal parietal walls of the right ventricle.

Results

The atrial septal defects varied in size between 8 and 33 millimetres, and were closed using occluders measuring from 10 to 40 millimetres. At 3 days after closure, the antero-posterior diameter of the right ventricle, the transverse diameter and length of the right atrium, the pulmonary arterial pressure, and the velocities of mural motion were all significantly decreased. After 3 months, the size of the right heart had more or less normalized.

Conclusions

Transcatheter closure of atrial septal defects produces marked improvement in the function and geometry of the chambers of the right heart, reducing pulmonary arterial pressure as well as abolishing the interatrial shunt.
Food patterns and Mediterranean diet in western and eastern Mediterranean islands
Authors: Romaguera Dora , Bamia Christina , Pons Antoni , Tur Josep A , Trichopoulou Antonia
Published: October 2008

Objective

To assess current Mediterranean dietary patterns (MDP) in the western and eastern Mediterranean, i.e. in Balearic islanders (BI) and Greek islanders (GI).

Subjects and methods

Dietary patterns were assessed using FFQ on a representative sample (n1200) of the BI and GI (n1324) adult population. A Mediterranean Diet Score (MDS) was calculated according to the consumption of nine MDP components: (i) with a beneficial effect on health, i.e. vegetables, fruits and nuts, cereals, legumes, fish and shellfish, MUFA:SFA ratio, and moderate alcohol consumption; and (ii) with a detrimental effect on health, i.e. meat and meat products, and milk and dairy products. Persons with consumption of beneficial components below the median (GI plus BI) received a value of 0 and those with consumption above the median a value of 1. Persons with below-median consumption of detrimental components received a value of 1 and above-median consumption a value of 0. For alcohol, a value of 1 was given to consumptions of 10–50 g/d (men) and 5–25 g/d (women). The range of the MDS was 0–9, with higher scores indicating greater adherence to the MDP.

Results

GI showed higher adherence (mean MDS 5·12 (sd1·42)) to the MDP than BI (mean MDS 3·32 (sd1·23)). BI diet was characterized by a high intake of legumes, nuts, seed oils, sugar and confectionery, and non-alcoholic beverages compared with GI, whereas GI diet was richer in fruit, vegetables, potatoes, olive oil, animal products and alcoholic beverages.

Conclusions

The GI diet seems closer to the traditional MDP than the BI diet.
Impact of targeted food supplementation on pregnancy weight gain and birth weight in rural Bangladesh: an assessment of the Bangladesh Integrated Nutrition Program (BINP)
Authors: Nahar Shamsun , Mascie-Taylor CG Nicholas , Begum Housne Ara
Published: October 2008

Objectives

To assess whether the Bangladesh Integrated Nutrition Programme (BINP) correctly identified which pregnant women should be enrolled in the food supplementation programme, whether supplementation commenced on time and was taken on a regular basis. A second objective was to determine whether food supplementation led to enhanced pregnancy weight gain and reduction in the prevalence of low birth weight.

Design

A one-year community-based longitudinal study.

Setting

A rural union of Bhaluka Upazila, Mymensingh, located 110 km north-west of Dhaka City, the capital of Bangladesh.

Participants

A total of 1104 normotensive, non-smoking pregnant women who attended Community Nutrition Centres were studied from first presentation at the centre until child delivery.

Results

Pregnant women who had a BMI of <18·5 kg/m2on first presentation should have been selected for supplementary feeding (2512 kJ (600 kcal)/d for six days per week) starting at month 4 (16 weeks) of pregnancy. However, of the 526 women who had BMI < 18·5 kg/m2, only 335 received supplementation; so the failure rate was 36·3 %. In addition, of those receiving supplementation, only 193 women (36·7 % of 526 women) commenced supplementation at the correct time, of whom thirty-two (9·6 % of 335 women) received supplementation for the correct number of days (100 % days). There were no significant differences in mean weight gain between BMI < 18·5 kg/m2supplemented or non-supplemented groups or between the equivalent groups with BMI ≥ 18·5 kg/m2. Weight gain was inversely related to initial weight, so lighter women gained relatively more weight during their pregnancy than heavier women. The mean birth weight in the supplemented and non-supplemented groups was 2·63 kg and 2·72 kg, respectively. Mothers with BMI < 18·5 kg/m2who were or were not supplemented had almost equal percentages of low-birth-weight babies (21 % and 22 %, respectively).

Conclusion

The study raises doubt about the efficiency of the BINP to correctly target food supplementation to pregnant women. It also shows that food supplementation does not lead to enhanced pregnancy weight gain nor does it provide any evidence of a reduction in prevalence of low birth weight.
Increasing dietary fish intake has contributed to decreasing mortality from CHD among the older population in Hong Kong
Authors: Zhang Xin-Hua , Woo Jean , Heller Richard F
Published: October 2008

Objective

To test whether change in the frequency of fish intake at population level would affect the trends of death from CHD and how many CHD events could be prevented in Hong Kong, a population among those with the highest fish consumption and the lowest CHD mortality in the world.

Design

Time trends analysis with data from repeated dietary surveys and death registration.

Setting

Hong Kong SAR, People’s Republic of China.

Subjects

A total of 3096 men and women aged 40–69 years who participated in territory-wide surveys in 1995 or 2003 were included in the analysis of changes in dietary fish intake; all adults aged 40–69 years in Hong Kong were included in the analysis of time trends of CHD mortality.

Results

Over the period, the frequency of fish intake increased and CHD mortality decreased significantly in the population age group of 50–69 years, while in the age group of 40–49 years little change in both fish intake and CHD mortality was observed. It was estimated that 240 CHD deaths (or 29 % of the total) were avoided among the population aged 40–69 years in 2003, as more than half of the population consumed fish every day in Hong Kong.

Conclusions

The time trend of CHD mortality was inversely related to the trend of fish intake. The frequency of fish intake may have a substantial impact on the population for the prevention of CHD deaths in Hong Kong.
Difference fields and descent in algebraic dynamics. II
Authors: Chatzidakis Zoé , Hrushovski Ehud
Published: October 2008

This second part of the paper strengthens the descent theory described in the first part to
rational maps and arbitrary base fields. We obtain in particular a decomposition of any difference field extension into a tower of finite, field-internal and one-based difference field extensions. This is needed in order to obtain the ‘dynamical Northcott’ Theorem 1.11 of Part I in sharp form.
Genericity, generosity, and tori
Authors: Cherlin Gregory
Published: October 2008

While the classification project for the simple groups of finite Morley rank is unlikely to
produce a classification of the simple groups of finite Morley rank, the enterprise has already arrived at a considerably closer approximation to that ideal goal than could have been realistically anticipated, with a mix of results of several flavors, some classificatory and others more structural, which can be combined when the stars are suitably aligned to produce results at a level of generality which, in parallel areas of group theory, would normally require either some additional geometric structure, or an explicit classification. And Bruno Poizat is generally awesome, though sometimes he goes too far.
Expansions of fields by angular functions
Authors: Evans David M.
Published: October 2008

The notion of an angular function has been introduced by Zilber as one possible way of connecting non-commutative geometry with two ‘counterexamples’ from model theory: the non-classical Zariski curves of Hrushovski and Zilber, and Poizat's field with green points. This article discusses some questions of Zilber relating to existentially closed structures in the class of algebraically closed fields with an angular function.
Groupes géométriques de rang de Morley fini
Authors: Frécon Olivier
Published: October 2008

We consider a new subgroup In(G) in any group G of finite Morley rank. This definably characteristic subgroup is the smallest normal subgroup of G from which we can hope to build a geometry over the quotient group G/ In(G). We say that G is a geometric group if In(G) is trivial.

This paper is a discussion of a conjecture which states that every geometric group G of finite Morley rank is definably linear over a ring K1 ⊕…⊕ Kn where K1,…,Kn are some interpretable fields. This linearity conjecture seems to generalize the Cherlin–Zil'ber conjecture in a very large class of groups of finite Morley rank.

We show that, if this linearity conjecture is true, then there is a Rosenlicht theorem for groups of finite Morley rank, in the sense that the quotient group of any connected group of finite Morley rank by its hypercentre is definably linear.
On types of CB-rank 1 in simple theories
Authors: Pillay Anand
Published: October 2008

We prove that if M0 is a model of a simple theory, and p(x) is a complete type of Cantor–Bendixon rank 1 over M0, then p is stationary and regular. As a consequence we obtain another proof that any countable model M0 of a countable complete simple theory T has infinitely many countable elementary extensions up to M0-isomorphism. The latter extends earlier results of the author in the stable case, and is a special case of a recent result of Tanovic.
Difference fields and descent in algebraic dynamics. I
Authors: Chatzidakis Zoé , Hrushovski Ehud
Published: October 2008

We draw a connection between the model-theoretic notions of modularity (or one-basedness), orthogonality and internality, as applied to difference fields, and questions of descent in in algebraic dynamics. In particular we prove in any dimension a strong dynamical version of Northcott's theorem for function fields, answering a question of Szpiro and Tucker and generalizing a theorem of Baker's for the projective line.

The paper comes in three parts. This first part contains an exposition some of the main results of the model theory of difference fields, and their immediate connection to questions of descent in algebraic dynamics. We present the model-theoretic notion of internality in a context that does not require a universal domain with quantifier-elimination. We also note a version of canonical heights that applies well beyond polarized algebraic dynamics. Part II sharpens the structure theory to arbitrary base fields and constructible maps where in part I we emphasize finite base change and correspondences. Part III will include precise structure theorems related to the Galois theory considered here, and will enable a sharpening of the descent results for non-modular dynamics.
Climate change impact on flood hazard in Europe: An assessment based on high‐resolution climate simulations
Authors: Dankers Rutger , Feyen Luc
Published: October 2008

Global warming is generally expected to increase the magnitude and frequency of extreme precipitation events, which may lead to more intense and frequent river flooding. This work assesses the implications of climate change for future flood hazard in Europe. Regional climate simulations from the HIRHAM model with 12‐km horizontal resolution were used to drive the hydrological model LISFLOOD, and extreme value techniques were applied to the results to estimate the probability of extreme discharges. It was found that by the end of this century under the Special Report on Emission Scenarios (SRES) A2 emissions scenario in many European rivers extreme discharge levels may increase in magnitude and frequency. In several rivers, most notably in the west and parts of eastern Europe, the return period of what is currently a 100‐year flood may in the future decrease to 50 years or less. A considerable decrease in flood hazard was found in the northeast, where warmer winters and a shorter snow season reduce the magnitude of the spring snowmelt peak. Also in other rivers in central and southern Europe a decrease in extreme river flows was simulated. The results were compared with those obtained with two HIRHAM experiments at 50‐km resolution for the SRES A2 and B2 scenarios. Disagreements between the various model experiments indicate that the effect of the horizontal resolution of the regional climate model is comparable in magnitude to the greenhouse gas scenario. Also, the choice of extreme value distribution to estimate discharge extremes influences the results, especially for events with higher return periods.
Effect of mesoscale topography over the Tibetan Plateau on summer precipitation in China: A regional model study
Authors: Shi Xiaoying , Wang Yuqing , Xu Xiangde
Published: October 2008

The effect of mesoscale topography over the Tibetan Plateau (TP) on downstream summer precipitation in China was studied using a regional atmospheric model. Two ensemble simulations with 30 km model resolution were conducted for the 1998 summer monsoon season in China. The control simulation used the uniform resolution for both model atmosphere and topography. In the sensitivity simulation, the mesoscale feature in topography over the TP was smoothed out with the use of the 120 km resolution topography over the TP. The results show that the control simulation reproduced reasonably well but the sensitivity simulation considerably underestimated the observed precipitation in the Yangtze River Valley (YRV). It is found that the mesoscale feature in topography plays an important role in generating and enhancing mesoscale disturbances over the TP. These disturbances enhance the surface sensible heat flux over the TP and propagate eastward to enhance convection and precipitation in the YRV in China.
Ionosphere response to solar wind high‐speed streams
Authors: Lei Jiuhou , Thayer Jeffrey P. , Forbes Jeffrey M. , Wu Qian , She Chengli , Wan Weixing , Wang Wenbin
Published: October 2008

We present 9‐ and 7‐day periodic oscillations in the global mean Total Electron Content (TEC) from 1 January 2005 to 31 December 2006. Spectral analysis indicates that the pronounced periodicities of 9 and 7 days observed in TEC are associated with variations in solar wind high‐speed streams and geomagnetic activity. Neutral temperature and winds near 250 km, measured by a Fabry‐Perot Interferometer at Resolute Bay, also exhibit 9‐ and 7‐day periodicities. These pronounced periodicities support simultaneous observations of 9‐ and 7‐day periodicities in thermosphere neutral density (Lei et al., 2008a; Thayer et al., 2008). It is anticipated that the ionospheric response at 9 and 7 days represents some combination of effects due to chemical loss, neutral winds, and disturbance dynamo‐driven electric fields.
Detecting precursory earthquake migration patterns using the pattern informatics method
Authors: Wu Yi‐Hsuan , Chen Chien‐chih , Rundle John B.
Published: October 2008

In this paper we analyze the evolution of seismic activity using a dynamic modification of the pattern informatics method. This method identifies locations that have systematic fluctuations in seismicity on PI maps. By investigating the evolution of hotspot configurations on the PI map and calculating the distance between hotspots and the epicenter of the impending large earthquake, a migrating pattern of (increasing or decreasing) precursory change in seismicity is revealed. We find that hotspots on the PI map appear increasingly closer to the epicenter as the time of the forthcoming earthquake is approached, implying the existence of an earthquake preparation process. The migration pattern and associated decreasing distance is confirmed by a stochastic test, and therefore we conclude that a preparation process prior to large earthquakes can be detected.
First results from the Spatial Heterodyne Imager for Mesospheric Radicals (SHIMMER): Diurnal variation of mesospheric hydroxyl
Authors: Englert Christoph R. , Stevens Michael H. , Siskind David E. , Harlander John M. , Roesler Fred L. , Pickett Herbert M. , von Savigny Christian , Kochenash Andrew J.
Published: October 2008

We present the first SHIMMER observations of the diurnal variation of mesospheric hydroxyl (OH). We compare our data with Aura Microwave Limb Sounder (MLS) observations at about 13h local time near 55°N and find very good agreement. This validates the Spatial Heterodyne Spectroscopy technique for space‐borne optical remote sensing applications. We extend our analysis to other local times, not observed by MLS, for latitudes near 55°N in the summer of 2007. At 74 km, we find excellent agreement with a photochemical model, but above 76 km, significant model/data differences in the shape of the OH diurnal variation are observed.
Avalanche statistics of driven granular slides in a miniature mound
Authors: Juanico D. E. , Longjas A. , Batac R. , Monterola C.
Published: October 2008

We examine avalanche statistics of rain‐ and vibration‐driven granular slides in miniature sand mounds. A crossover from power‐law to non power‐law avalanche‐size statistics is demonstrated as a generic driving rate ν is increased. For slowly‐driven mounds, the tail of the avalanche‐size distribution is a power‐law with exponent −1.97 ± 0.31, reasonably close to a value previously reported for landslide volumes. The interevent occurrence times are also analyzed for slowly‐driven mounds; its distribution exhibits a power‐law with exponent −2.670 ± 0.001.
Organic molecular compositions and temporal variations of summertime mountain aerosols over Mt. Tai, North China Plain
Authors: Fu Pingqing , Kawamura Kimitaka , Okuzawa Kazuhiro , Aggarwal Shankar Gopala , Wang Gehui , Kanaya Yugo , Wang Zifa
Published: October 2008

Total suspended particles (TSP) were collected at the summit of Mt. Tai (1534 m above sea level) on a daytime and nighttime basis during a summertime campaign (May–June 2006) and were characterized for organic molecular compositions using solvent extraction/derivatization and gas chromatography/mass spectrometry technique. The n‐Alkanes, fatty acids, fatty alcohols, sugars, glycerol and polyacids, and phthalate esters were found as major organic compound classes, whereas lignin and resin products, sterols, aromatic acids, hopanes, and polycyclic aromatic hydrocarbons (PAHs) were detected as minor classes. Sugars (49.8–2115 ng m−3, average 640 ng m−3 in daytime; 18.1–4348 ng m−3, 799 ng m−3 in nighttime) were found to be the dominant compound class. Levoglucosan, a specific cellulose pyrolysis product, was detected as the most abundant single compound, followed by C28 fatty alcohol, diisobutyl and di‐n‐butyl phthalates, C29n‐alkane, C16 and C28 fatty acids, and malic acid. By grouping organic compounds based on their sources, we found that emission of terrestrial plant waxes was the most significant source (30–34%) of the TSP, followed by biomass burning products (25–27%) (e.g., levoglucosan and lignin and resin products), soil resuspension (15–18%) due to agricultural activities, secondary oxidation products (8–10%), plastic emission (3–10%), marine/microbial sources (6%), and urban/industrial emissions from fossil fuel use (4%). However, low molecular weight dicarboxylic acids (such as oxalic acid) of photochemical origin were not included in this study. Malic acid was found to be much higher than those reported in the ground level, suggesting an enhanced photochemical production in the free troposphere over mountain areas. Temporal variations of biomass burning tracers (e.g., levoglucosan, galactosan, mannosan) and some higher plant wax derived compound classes suggested that there were two major (E1 and E2) and one minor (E3) biomass‐burning events during this campaign. Most of the compound classes showed higher concentrations in nighttime samples when organic aerosols can be long‐range transported from different source regions to the summit of Mt. Tai above the planetary boundary layer (PBL). This study also demonstrates that the free troposphere over Mt. Tai is heavily influenced by field burning of agricultural wastes such as wheat straws in the North China Plain during the harvest season in early summer.
Parameterization of the effects of vertically propagating gravity waves for thermosphere general circulation models: Sensitivity study
Authors: Yiğit Erdal , Aylward Alan D. , Medvedev Alexander S.
Published: October 2008

A parameterization of gravity wave (GW) drag, suitable for implementation into general circulation models (GCMs) extending into the thermosphere is presented. Unlike existing schemes, the parameterization systematically accounts for wave dissipation in the upper atmosphere due to molecular viscosity, thermal conduction, ion friction, and radiative damping in the form of the Newtonian cooling. This is in addition to using the commonly employed breaking/saturation schemes, based on either linear Hodges‐Lindzen instability criteria or its nonlinear extension to multiple‐harmonic spectra. The scheme was evaluated in a series of tests of increasing complexity. In the thermosphere, the simulations suggest that the dissipation competes with the instability caused by amplitude growth, and can seriously alter GW propagation and the associated wave drag. Above the mesopause the GW drag is generally created by harmonics with fast horizontal phase velocities, which under favorable conditions can propagate into the F2 layer. The effects of thermospheric dissipation are more complex than a simple exponential decay of GW fluxes above certain levels. We examine the sensitivity of the GW drag profiles to the variations of the source spectra typically employed in GCMs. These results suggest that GWs can provide strong coupling between the meteorological events in the lower atmosphere and the circulation well above the middle atmosphere.
Nitrogen and carbon uptake dynamics in Lake Superior
Authors: Kumar Sanjeev , Sterner Robert W. , Finlay Jacques C.
Published: October 2008

Despite a fivefold rise in nitrate concentration over the last century, many fundamental aspects of Lake Superior's N and C cycles are still very poorly understood. We present here the first measurements of inorganic N uptake and in situ C uptake rates in Lake Superior, one of the largest lakes in the world. A profile of C uptake suggests that more than 95% of production occurs in the top 30 m with highest productivity to biomass ratio in the epilimnion. High C uptake:N uptake and particulate C: N ratio compared to the Redfield ratio (6.6) in the epilimnion suggests higher turnover rate of C compared to N in epilimnetic particles. Experiments performed over a range of typical environmental conditions suggest a strong temperature dependence of N uptake with maximum rates observed during the warmest stratified period. Lakewide N uptake estimates derived from a temperature‐based model suggest that on an annual basis, uptake is considerably higher than total N inputs from outside the lake. This difference indicates that the lake is recycling N rapidly, leading to a shorter turnover time in the water column than previously assumed. The long‐term buildup of nitrate in the lake has been hypothesized to arise from limited assimilation of nitrate entering the lake. In contrast, our results suggest that nitrate accumulating in the lake is a result of internal N cycling, a finding consistent with recent studies based on a nitrogen budget and NO3− stable isotope analyses.
IL‐5‐overexpressing mice exhibit eosinophilia and altered wound healing through mechanisms involving prolonged inflammation
Authors: Leitch Victoria D , Strudwick Xanthe L , Matthaei Klaus I , Dent Lindsay A , Cowin Allison J
Published: October 2008

Leucocytes are essential in healing wounds and are predominantly involved in the inflammatory and granulation stages of wound repair. Eosinophils are granulocytic leucocytes and are specifically regulated by interleukin‐5 (IL‐5), a cytokine produced by T helper 2 (Th2) cells. To characterize more clearly the role of the IL‐5 and eosinophils in the wound healing process, IL‐5‐overexpressing and IL‐5‐deficient mice were used as models of eosinophilia and eosinophil depletion, respectively. Our results reveal a significantly altered inflammatory response between IL‐5‐overexpressing and IL‐5 knockout mice post‐wounding. Healing was significantly delayed in IL‐5‐overexpressing mice with wounds gaping wider and exhibiting impaired re‐epithelialization. A delay in collagen deposition was observed suggesting a direct effect on matrix synthesis. A significant increase in inflammatory cell infiltration, particularly eosinophils and CD4+ cells, one of the main cell types which secrete IL‐5, was observed in IL‐5‐overexpressing mice wounds suggesting that one of the main roles of IL‐5 in wound repair may be to promote the infiltration of eosinophils into healing wounds. Healing is delayed in IL‐5‐overexpressing mice and this corresponds to significantly increased levels of eosinophils and CD4+ cells within the wound site that may contribute to and exacerbate the inflammatory response, resulting in detrimental wound repair.
GM‐CSF deficiency delays neointima formation in a normolipidemic mouse model of endoluminal endothelial damage
Authors: Harris Angie K , Shen Jie , Radford Jane , Bao Shisan , Hambly Brett D
Published: October 2008

Granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) has been implicated in atherogenesis and has been shown to have both pro‐ and antiatherogenic properties. Neointimal thickening is a prominent feature of early atherogenesis. This study aimed to examine the role of GM‐CSF in neointimal formation induced by endothelial injury using a GM‐CSF−/− mouse model. Neointimal thickening was induced by endothelial damage in the common iliac arteries of normolipidemic C57Bl/6 (wild‐type) and GM‐CSF−/− mice. Arteries were collected weekly for 3–7 weeks following surgery. A significant delay in neointimal formation in the GM‐CSF−/− compared with wild‐type mice was detected by morphometric analysis of the intimal area. Neointimal size was ∼10% smaller in GM‐CSF−/− mice at 4–6 weeks post‐surgery, compared with wild‐type mice. The neointima was composed predominantly of smooth muscle cells and there was no difference in the extent of endothelial cell coverage between the wild‐type and GM‐CSF−/− mice. Using immunohistochemistry, reduced macrophages (F4/80+ cells), proliferating cells (proliferating cell nuclear antigen (PCNA)+ cells) and platelet‐derived growth factor‐B were detected within the arteries of GM‐CSF−/− mice compared with wild types at 4 weeks post‐surgery. GM‐CSF−/− mice had reduced connective tissue within the neointima compared with wild types at 5 weeks post‐surgery, determined by trichrome staining. We conclude that GM‐CSF deficiency reduces neointimal formation in a normolipidemic model, primarily due to reduced macrophage recruitment.
Sulphide GaxGe25−xSb10S65(x=,5) sputtered films: Fabrication and optical characterizations of planar and rib optical waveguides
Authors: Charrier J. , Anne M. L. , Lhermite H. , Nazabal V. , Guin J. P. , Charpentier F. , Jouan T. , Henrio F. , Bosc D. , Adam J. L.
Published: October 2008

We report the fabrication and the physical and optical characterizations of sulphide GaxGe25−xSb10S65(x=0,5) rib waveguides. High quality films fabricated on SiO2/Si wafer substrates were obtained using the sputtering magnetron rf deposition method. The slab waveguides obtained without annealing present propagation losses of about 0.6 dB/cm at 1550 nm. These optical losses are not important for implementation in optical devices based on silicon-on-insulator or polymer, for instance, atomic force microscopy measurements revealed low interface roughness between the different media (substrate/film and film/air). Reactive ion etching was used to pattern rib waveguides between 2 and 300 μm wide. The parameters were optimized to obtain a dry etching process that had low surface roughness, vertical sidewalls, etch depth of more than 1 μm, and reasonable etching rate. This technique was used to fabricate Y optical junctions for optical interconnections on chalcogenide amorphous films. Their optical transmission was demonstrated by optical near field of guided modes and optical losses were measured and discussed.
Ferroelectric properties, morphologies, and leakage currents of Bi0.97La0.03FeO3 thin films deposited on indium tin oxide/glass substrates
Authors: Yan J. , Hu G. D. , Chen X. M. , Wu W. B. , Yang C. H.
Published: October 2008

Bi 0.97 La 0.03 FeO 3 (BLFO) films were prepared using the metal organic decomposition method on indium tin oxide (ITO)/glass substrates. Ferroelectric properties, morphologies and leakage currents of BLFO thin fims are very sensitive to the annealing temperature. The content of grain boundaries in the films is considered to be the dominant factor affecting the leakage currents in BLFO films. Well saturated P-E hysteresis loops can be obtained from all BLFO films due to their low leakage currents. The BLFO thin film annealed at 525 °C exhibits the highest remanent polarization (Pr≈72.9 μC/cm2), which can be explained by the high relative intensity of (110) peak.
Postpolymerization alignment of bulk conjugated polymers
Authors: Wilson Tiffany M. S. , Chinn Douglas A. , Robinson David B. , Doty F. P.
Published: October 2008

We have demonstrated postpolymerization stretch alignment of substituted conjugated polymers as evidenced by polarized infrared spectroscopy, with a Hermans orientation function value of 0.66 for a stretch ratio of 3.7. The effects of stretch rate and substrate on the material order are examined. We further show that the stretch-induced increase in long-range order leads to an increase in photoconductive response parallel to the stretch direction, and a decrease in the orthogonal direction. The introduction of small amounts of substituted fullerenes does not interfere with the ordering of the polymer on a bulk scale.
Lamellar to micelle transition of nonionic surfactant assemblies induced by addition of colloidal particles
Authors: Suganuma Yukiko , Urakami Naohito , Mawatari Rina , Komura Shigeyuki , Nakaya-Yaegashi Kaori , Imai Masayuki
Published: October 2008

We have investigated the entropic interactions between lamellar membranes and spherical colloidal particles using a small-angle neutron scattering (SANS) technique. By adding colloidal particles between lamellar sheets, the first lamellar peaks in SANS profiles become intense and the second and higher order Bragg peaks begin to appear, indicating that the membrane fluctuations are suppressed by the colloidal particles. We estimate the interlamellar interaction potential in the presence of the colloidal particles from the layer compressibility obtained by the SANS profile analysis and propose a phenomenological free energy model based on the restriction of membrane fluctuations. By further addition of the colloidal particles, the lamellar membranes transform to prolate micelles. In order to release the strong frustration due to the restriction of membrane fluctuations, the surfactant assemblies change the morphology from the two dimensional sheets to the one dimensional prolate micelles.
Piezoelectric behavior of SrRuO3 buffered lanthanum modified bismuth ferrite thin films grown by chemical method
Authors: Simões A. Z. , Gonzalez A. H. M. , Aguiar E. C. , Riccardi C. S. , Longo E. , Varela J. A.
Published: October 2008

Lanthanum modified bismuth ferrite thin film (BLFO) of pure perovskite phase was deposited on SrRuO3-buffered Pt/TiO2/SiO2/Si (100) substrates by soft chemical method. (111)-preferred oriented BLFO film was coherently grown at a temperature of 500 °C. The crystal structure of the film was characterized by using x-ray diffraction. The spontaneous polarization of the film was 25 μC/cm2. The film has a piezoelectric coefficient d33 equal to 85 pm/V and a weak pulse width dependence indicating intrinsic ferroelectricity. Retention measurement showed no decay of polarization while piezoelectric response was greatly improved by the conductor electrode.
Vibrational spectroscopy of InAlAs epitaxial layers
Authors: Milekhin A. G. , Kalagin A. K. , Vasilenko A. P. , Toropov A. I. , Surovtsev N. V. , Zahn D. R. T.
Published: October 2008

Raman and IR spectroscopies were applied for the investigation of optical phonons in relaxed InxAl1−xAs alloys grown by molecular-beam epitaxy on GaAs. From the analysis of Raman and IR data, the frequencies of longitudinal and transverse InAs- and AlAs-like optical phonons were derived in the whole composition range of the alloy (x=0–1). Analytical expressions are obtained for the frequency variation with In composition for the optical phonon modes, as well as the variations in their intensity and linewidth. Multiple-phonon Raman scattering up to the fourth order is observed under resonant conditions.
Energetics and kinetics of Ti clustering on neutral and charged C60 surfaces
Authors: Yang Shenyuan , Yoon Mina , Wang Enge , Zhang Zhenyu
Published: October 2008

Using ab initio spin density functional theory, we investigate the energetics and kinetics of Ti clustering on both neutral and charged C60 surfaces. We compare the formation energy of sparsely dispersed zero-dimensional (0D), compact single-layered two-dimensional (2D), and clustered three-dimensional (3D) TiN configurations as a function of cluster size (N⩽12) and further study the transformation kinetics between them. We find that 0D configuration is always less stable than that of 2D and 3D configurations and 0D to 2D transformation involves in a single Ti diffusion process with kinetic barrier of ⩽0.7eV. On the other hand, there exists a critical cluster size (NC) of NC=5, below which 2D layers are preferred to 3D clusters. Hole- or B-doping greatly enhance the Ti-fullerene interaction and lead to stronger dispersion of Ti atoms. Even so, for moderate charge doping (less than seven holes) the critical size of Ti atoms on neutral C60 surprisingly remains unchanged or only slightly increases to NC=6 by B-doping. However, we find that the formation of 3D clusters may be hindered by a high kinetic barrier related to the process of single Ti atoms climbing up a single Ti layer. This barrier is ∼1eV or even 1.47eV for B-doped C60 surfaces which is high enough to stabilize larger 2D structures (N⩾NC) at low temperatures. These findings may prove to be instrumental in stabilizing transition metal coated nanostructures and especially homogeneously Ti-coated fullerenes, which are believed to be a very promising material for hydrogen storage.
Phase change nanodots patterning using a self-assembled polymer lithography and crystallization analysis
Authors: Zhang Yuan , Raoux Simone , Krebs Daniel , Krupp Leslie E. , Topuria Teya , Caldwell Marissa A. , Milliron Delia J. , Kellock Andrew , Rice Philip M. , Jordan-Sweet Jean L. , Wong H.-S. Philip
Published: October 2008

Crystallization behavior of scalable phase change materials can be studied on nanoscale structures. In this paper, high density ordered phase change nanodot arrays were fabricated using the lift-off technique on a self-assembled diblock copolymer template, polystyrene-poly(methyl-methacrylate). The size of the nanodots was less than 15 nm in diameter with 40 nm spacing. This method is quite flexible regarding the patterned materials and can be used on different substrates. The crystallization behavior of small scale phase change nanodot arrays was studied using time-resolved x-ray diffraction, which showed the phase transition for different materials such as Ge15Sb85, Ge2Sb2Te5, and Ag and In doped Sb2Te. The transition temperatures of these nanodot samples were also compared with their corresponding blanket thin films, and it was found that the nanodots had higher crystallization temperatures and crystallized over a broader temperature range.
A review on dielectric elastomer actuators, technology, applications, and challenges
Authors: O’Halloran Ailish , O’Malley Fergal , McHugh Peter
Published: October 2008

This paper reviews the developments in dielectric elastomer actuator technology for several applications. Dielectric elastomers are a variety of electroactive polymer that deform due to the electrostatic interaction between two electrodes with opposite electric charge. Dielectric elastomers have been subject of much interest and research over the past decade. In earlier years, much of the focus was on actuator configurations, and in more recent years the focus has turned to investigating material properties that may enhance actuator performance. This review outlines the operating principle and actuation mechanisms behind this actuator technology, highlights some of its advantages over existing actuator technologies, identifies some of the challenges associated with its development, and examines the main focus of research within this field, including some of the potential applications of such an actuator technology.
Calculation of vibrational energy of molecule using coupled cluster linear response theory in bosonic representation: Convergence studies
Authors: Banik Subrata , Pal Sourav , Prasad M. Durga
Published: October 2008

Vibrational excited state energies have been calculated using vibrational coupled cluster linear response theory (CCLRT). The method has been implemented on formaldehyde and water molecule. Convergence studies have been shown with varying the cluster operator from S4 to S6 as well as the excitation operator from four bosons to six bosons. A good agreement with full configuration interaction results has been observed with S6 truncation at coupled-cluster method level and six bosonic excitations at CCLRT level.
Modeling of a negative ion source. II. Plasma-gas coupling in the extraction region
Authors: Taccogna F. , Schneider R. , Longo S. , Capitelli M.
Published: October 2008

The production, destruction, and transport of H− in the extraction region of a negative ion source are investigated with a 1D(z)-3V particle-in-cell electrostatic code. The motion of charged particles (e, H+, H2+, and H−) in their self-consistent electric field is coupled with the neutral particles [H(n=1) and H2(X1∑g+,v=0,…,14)] dynamics and vibrational kinetics of H2. Neutral influxes into the domain are determined by the simulation of the expansion region. Surface and volumetric processes involving plasma and neutrals have been included by using different Monte Carlo collision methods. Calculations show the influence of the plasma grid bias and of the magnetic filter on the plasma parameter profiles. In particular, a transition from classical to complete reverse sheath is observed using a positively biased plasma grid. The influence of the magnetic filter is small. The importance of the hot-atom mechanism on the surface negative ion production is shown.
Rotational molecular dynamics of laser-manipulated bromotrifluoromethane studied by x-ray absorption
Authors: Buth Christian , Santra Robin
Published: October 2008

We present a computational study of the rotational molecular dynamics of bromotrifluoromethane (CF3Br) molecules in gas phase. The rotation is manipulated with an off-resonant 800 nm laser. The molecules are treated as rigid rotors. Frequently, we use a computationally efficient linear rotor model for CF3Br, which we compare with selected results for full symmetric-rotor computations. The expectation value ⟨cos2 ϑ⟩(t) is discussed. Especially, the transition from impulsive to adiabatic alignment, the temperature dependence of the maximally achievable alignment, and its intensity dependence are investigated. In a next step, we examine resonant x-ray absorption as an accurate tool to study laser manipulation of molecular rotation. Specifically, we investigate the impact of the x-ray pulse duration on the signal (particularly its temporal resolution) and study the temperature dependence of the achievable absorption. Most importantly, we demonstrated that using picosecond x-ray pulses, one can accurately measure the expectation value ⟨cos2 ϑ⟩(t) for impulsively aligned CF3Br molecules. We point out that a control of the rotational dynamics opens up a novel way to imprint shapes onto long x-ray pulses on a picosecond time scale. For our computations, we determine the dynamic polarizability tensor of CF3Br using ab initio molecular linear-response theory in conjunction with wave function models of increasing sophistication: Coupled-cluster singles (CCS), second-order approximate coupled-cluster singles and doubles (CC2), and coupled-cluster singles and doubles (CCSD).
A crossed molecular beam study on the synthesis of the interstellar 2,4-pentadiynylidyne radical (HCCCCC)
Authors: Zhang Fangtong , Kim Yong Seol , Zhou Li , Chang Agnes H. H. , Kaiser Ralf I.
Published: October 2008

Crossed molecular beam experiments are performed to elucidate the synthesis of the 2,4-penta-diynylidyne [HCCCCC(XΠ2)] radical under single collision conditions—a crucial reaction intermediate to form polycyclic aromatic hydrocarbons and carbonaceous nanostructures in the interstellar medium and in combustion flames. The experiments demonstrate that the chemical dynamics of ground state carbon reacting with diacetylene [HCCCCH(XΣg+1)] are indirect and proceed via addition of the electrophilic carbon atom to the π electron density of the diacetylene molecule yielding ultimately the carbenelike HCCCCCH(XΣg−3) molecule. This intermediate fragments via hydrogen atom emission to yield the 2,4-pentadiynylidyne [HCCCCC(XΠ2)] radical. The chemical dynamics elucidated also allows us to predict that reaction of carbon atoms with polyynes of the generic formula H(CC)nH leads to the formation of hydrogen-terminated carbon clusters of the generic form HC2n+1 in extreme environments. The acetylene-related reactivity and electronic structure of the diacetylene molecule also allow us to project that reactions of the diacetylene molecule with cyano and ethynyl radicals result in a stepwise extension of the carbon skeleton forming cyanodiacetylene (HCCCCCN) and triacetylene (HCCCCCCH) plus atomic hydrogen. These predictions open the door to extensive laboratory studies involving hitherto poorly understood reactions of the diacetylene molecule under single collision conditions.
A self-consistent Hubbard U density-functional theory approach to the addition-elimination reactions of hydrocarbons on bare FeO+
Authors: Kulik Heather J. , Marzari Nicola
Published: October 2008

We present a detailed analysis of the addition-elimination reaction pathways for the gas-phase conversion of molecular hydrogen and methane on FeO+ to water and methanol, respectively, using first-principles calculations. These two reactions represent paradigmatic, challenging test cases for electronic structure approaches to transition-metal catalysis. We compare here density-functional approaches against state-of-the-art coupled-cluster and multireference quantum chemistry approaches. The quantum chemical approaches are found to be in close agreement between themselves as well as with the available experimental evidence. For the density-functional calculations, we employ a recently introduced ab initio, self-consistent Hubbard-like correction, coupled here with a generalized-gradient approximation (GGA) for the exchange-correlation functional. We find that our formulation provides a remarkable improvement in the description of the electronic structure, hybridization, and multiplet splittings for all calculated stationary points along these reaction pathways. The Hubbard term, which is not a fitting parameter and, in principle, can augment any exchange-correlation functional, brings the density-functional theory results in close agreement with the reference calculations. In particular, thermochemical errors as large as 1.4 eV in the exit channels with the GGA functional are reduced by an order of magnitude, to less than 0.1 eV on average; additionally, close agreement with the correlated-electron reference calculations and experiments are achieved for intermediate spin splittings and structures, reaction exothermicity, and spin crossovers. The role that the Hubbard U term plays in improving both quantitative and qualitative descriptions of transition-metal chemistry is examined, and its strengths as well as possible weaknesses are discussed in detail.
Robust Ohmic contact junctions between metallic tips and multiwalled carbon nanotubes for scanned probe microscopy
Authors: Kim Suenne , Kim Jeehoon , Berg Morgann , de Lozanne Alex
Published: October 2008

We demonstrate a simple method that uses a scanning electron microscope for making a reliable low resistance contact between a single multiwalled carbon nanotube and a metallic tungsten probe tip or a Si cantilever. This method consists of using electron beam induced decomposition of background gases and voltage pulses to remove contaminants. The electrical quality of the contact is monitored in situ by measuring the current flow at constant bias or by observing the decay of current fluctuations. The quality of the contacts is confirmed via current-voltage spectroscopy. This method produces very stable, low resistance, mechanically robust contacts with high success rates approaching 100%.
Asymmetric spatiotemporal chaos induced by a polypoid mass in the excised larynx
Authors: Zhang Yu , Jiang Jack J.
Published: October 2008

In this paper, asymmetric spatiotemporal chaos induced by a polypoid mass simulating the laryngeal pathology of a vocal polyp is experimentally observed using high-speed imaging in an excised larynx. Spatiotemporal analysis reveals that the normal vocal folds show spatiotemporal correlation and symmetry. Normal vocal fold vibrations are dominated mainly by the first vibratory eigenmode. However, pathological vocal folds with a polypoid mass show broken symmetry and spatiotemporal irregularity. The spatial correlation is decreased. The pathological vocal folds spread vibratory energy across a large number of eigenmodes and induce asymmetric spatiotemporal chaos. High-order eigenmodes show complicated dynamics. Spatiotemporal analysis provides a valuable biomedical application for investigating the spatiotemporal chaotic dynamics of pathological vocal fold systems with a polypoid mass and may represent a valuable clinical tool for the detection of laryngeal mass lesion using high-speed imaging.
Self-assembled nanotube field-effect transistors for label-free protein biosensors
Authors: Hu P. , Fasoli A. , Park J. , Choi Y. , Estrela P. , Maeng S. L. , Milne W. I. , Ferrari A. C.
Published: October 2008

A self-assembly method is developed to fabricate single-wall carbon nanotube field-effect transistors (SWNT-FETs). The electrode surface and the area between electrodes are modified with nonpolar groups (−CH3) and polar groups (−NH3+). SWNTs are selectively placed in the area between the electrodes. We achieve stability and specificity in label-free protein detection using the biotin-streptavidin pair as research model. Our process holds promise for high integration of SWNT-FET biosensors, with no need for high-temperature processing.