bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasound assessment of cervical length in prolonged pregnancy: prediction of spontaneous onset of labor and successful vaginal delivery
Authors: Vankayalapati P. , Sethna F. , Roberts N. , Ngeh N. , Thilaganathan B. , Bhide A.
Published: February 2008

Objectives

To evaluate the usefulness of sonographic assessment of cervical length in the prediction of spontaneous onset of labor and of vaginal delivery.

Methods

Two hundred and six women who attended a dedicated postdates clinic at 41 + 3 weeks of pregnancy and agreed to the assessment of cervical length using transvaginal ultrasound imaging were included in the study. Those who had not delivered at 42 weeks were offered induction of labor. The labor details were recorded prospectively, and the onset of spontaneous labor and mode of delivery were correlated with cervical length data.

Results

Women who underwent spontaneous onset of labor (n = 112) had a significantly shorter cervical length (mean (SD) 25.0 (8.3) mm) than had women whose labor was induced (n = 67; mean (SD) 29.7 (8.5) mm). Logistic regression analysis showed that cervical length was an independent predictor of the likelihood of spontaneous labor in nulliparous women, and of vaginal delivery in both nulliparous and parous women. Parity had no independent effect on the onset of spontaneous labor, but was an independent predictor of the likelihood of vaginal delivery.

Conclusions

Sonographic assessment of cervical length is a significant independent predictor of the likelihood of the onset of spontaneous labor in nulliparous women, and of successful vaginal delivery in both nulliparous and parous women with prolonged pregnancy. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Hypothermia/Warming Protocols: Why Are They Not Widely Used in the OR?
Authors: Weirich Tara Lynn
Published: February 2008

HYPOTHERMIA, A COMMON PROBLEM for patients having surgery, adversely affects multiple organ systems and physiologic functions. Research indicates that maintaining normothermia can reduce infection rates, operative blood loss, and length of hospital stay.

OFTEN, PREVENTING HYPOTHERMIA is not a high priority to surgical staff members because forced‐air warming systems may cause field contamination and passive warming may increase the ambient OR temperature. In addition, inconsistent practices and lack of guidelines may affect team members' efforts.

SURGICAL TEAM AWARENESS, education, and understanding of the effects of hypothermia are necessary components to enhance the ways clinicians provide quality, cost‐effective patient care. AORN J 87 (February 2008) 333‐344. © AORN, Inc, 2008.
Unilateral improvement in glomerular filtration rate after permanent drainage of a perinephric pseudocyst in a cat
Authors: McCord Kelly , Steyn Philip F. , Lunn Katharine F.
Published: February 2008

A 12-year-old, 6 kg, castrated male Siamese-cross cat was referred for investigation of an abdominal mass. The cat was found to have a left perinephric pseudocyst (PNP), accompanied by azotemia, with a small right kidney detected on ultrasound. Glomerular filtration rate (GFR) was determined by renal scintigraphy and was found to be low, with the left kidney contributing 64% of the total GFR. Percutaneous ultrasound-guided drainage of the PNP did not improve the GFR, and fluid reaccumulated within a short period of time. Laparoscopic fenestration of the cyst capsule was performed to allow for permanent drainage. The PNP did not recur, renal values progressively improved, and 8 months after the capsulotomy the GFR of the left kidney had increased by 50%, while renal function remained static on the right side.
The Politics of When: Redistribution, Investment and Policy Making for the Long Term
Authors: JACOBS ALAN M.
Published: February 2008

Why do some elected governments impose short-term costs to invest in solving long-term social problems while others delay or merely redistribute the pain? This article addresses that question by examining the politics of pension reform in Britain and the United States. It first reframes the conventional view of the outcomes – centred on cross-sectional distribution – demonstrating that the politicians who enacted the least radical redistribution enacted the most dramatic intertemporal tradeoffs. To explain this pattern, the article develops and tests a theory of policy choice in which organized interests struggle for long-term advantage under institutional constraints. The argument points to major analytical advantages to studying governments' policy choices in intertemporal terms, for both the identification of comparative puzzles and their explanation.
Political Competition and Democratic Stability in New Democracies
Authors: WRIGHT JOSEPH
Published: February 2008

This article examines the way in which the initial level of political competition in a new democracy affects the stability of that regime. The author argues that new democracies with low levels of initial political competition are more likely to fail because those initially excluded from the democratic game seek to subvert the regime in the future. Using data from ninety-two new democracies born since 1946, he finds that a higher level of initial political competition in a new democracy makes for a more durable democracy. New democracies at war and born during the Cold War are less likely to survive. Finally, he finds evidence that new democracies with low levels of initial political competition are also more likely to meet with civil conflict.
New Forms of Political Participation: Searching for Expert Citizens and Everyday Makers
Authors: LI YAOJUN , MARSH DAVID
Published: February 2008

Declining political participation has caused much concern among political scientists and politicians. This article builds upon Henrik Bang's conceptualization of Expert Citizens and Everyday Makers as new forms of political participation. Using the 2001 Home Office Citizenship Survey, we identify four types of political participant: Political Activists, Expert Citizens, Everyday Makers and Non-Participants. We assess the socio-demographic and cultural factors underlying these different types of participant. We then move on to explore the association between the types of political participation and two domains of political beliefs/actions: political trust and efficacy; and political contacting and voice. Our analysis shows significant differences between the types of participant in the two domains under investigation and thus lends support to our development of Bang's conceptualization of new forms of political participation as useful tools in empirical research.
Emanating Political Participation: Untangling the Spatial Structure Behind Participation
Authors: CHO WENDY K TAM , RUDOLPH THOMAS J
Published: February 2008

This is an analysis of the spatial structure of political participation in the United States using spatial econometric techniques and newly available geo-coded data. The results provide strong evidence that political participation is geographically clustered, and that this clustering cannot be explained entirely by social network involvement, individual-level characteristics, such as race, income, education, cognitive forms of political engagement, or by aggregate-level factors such as racial diversity, income inequality, mobilization or mean education level. The analysis suggests that the spatial structure of participation is consistent with a diffusion process that occurs independently from citizens' involvement in social networks.
Political Interest, Cognitive Ability and Personality: Determinants of Voter Turnout in Britain
Authors: DENNY KEVIN , DOYLE ORLA
Published: February 2008

This article uses longitudinal data from the National Child Development Study (NCDS) to investigate the determinants of voter turnout in the 1997 British general election. It introduces measures of cognitive ability and personality into the participation literature and finds that they are significant determinants of turnout. It also shows that standard turnout models may be biased by the inclusion of the much used ‘interest in politics’ measure. A bivariate probit model of turnout and political interest finds that individuals with high comprehension ability and an aggressive personality are more likely to both turn out to vote and have an interest in politics.
Support for an independent familial segregation of executive and intelligence endophenotypes in ADHD families
Authors: Rommelse N. N. J. , Altink M. E. , Oosterlaan J. , Buschgens C. J. M. , Buitelaar J. , Sergeant J. A.
Published: February 2008

Background

Impairments in executive functioning (EF) and intelligence quotient (IQ) are frequently observed in children with attention deficit hyperactivity disorder (ADHD). The aim of this paper was twofold: first, to examine whether both domains are viable endophenotypic candidates for ADHD and second to investigate whether deficits in both domains tend to co-segregate within families.

Method

A large family-based design was used, including 238 ADHD families (545 children) and 147 control families (271 children). Inhibition, visuospatial and verbal working memory, and performance and verbal IQ were analysed.

Results

Children with ADHD, and their affected and non-affected siblings were all impaired on the EF measures and verbal IQ (though unimpaired on performance IQ) and all measures correlated between siblings. Correlations and sibling cross-correlations were not significant between EF and IQ, though they were significant between the measures of one domain. Group differences on EF were not explained by group differences on IQ and vice versa. The discrepancy score between EF and IQ correlated between siblings, indicating that siblings resembled each other in their EF–IQ discrepancy instead of having generalized impairments across both domains. Siblings of probands who had an EF but not IQ impairment, showed a comparable disproportionate lower EF score in relation to IQ score. The opposite pattern was not significant.

Conclusions

The results supported the viability of EF and IQ as endophenotypic candidates for ADHD. Most findings support an independent familial segregation of both domains. Within EF, similar familial factors influenced inhibition and working memory. Within IQ, similar familial factors influenced verbal and performance IQ.
French liaison in the light of corpus data
Authors: DURAND JACQUES , LYCHE CHANTAL
Published: February 2008

French liaison has long been a favourite testing ground for phonological theories, a situation which can undoubtedly be attributed to the complexity of the phenomenon, involving in particular phonology/syntax, phonology/morphology, phonology/lexicon interfaces. Dealing with liaison requires stepping into all the components of the grammar, while at the same time tackling the quick sands of variation. The data on which a number of formal analyses are based have often been a source of concern since liaison, in part because of its intrinsic variable character, requires extensive and robust data. In the wake of the results from the study of other corpora, we present here extensive results based on the PFC database (Phonologie du français contemporain: usages, variétés et structures) and point to their implications for models of linguistic structure. While we do not believe that a motivated theoretical account can be mechanically extracted from the data, we conclude that future analyses will have to take explicitly into account the results of extensive corpus work as well as sociolinguistic surveys, acquisition studies, experimental phonetics and (neuro-)psycho-linguistic investigations, including the relationship between speech and writing. As stressed in Chevrot, Fayol and Laks (2005), these analyses will have to acknowledge that French liaison is not a homogeneous locus but a multi-faceted phenomenon requiring us to accept, without demur, the crossing of disciplinary boundaries.
Extensive data for morphology: using the World Wide Web
Authors: HATHOUT NABIL , MONTERMINI FABIO , TANGUY LUDOVIC
Published: February 2008

This paper presents a number of recent studies in French morphology which make extensive use of data. These data relating to derived words have been automatically collected from digital corpora, mostly from the Web. The main point developed here is that this massive increase in the amount of available data can substantially modify the results of a morphological study, and can lead to new theoretical conclusions that would not have been possible with traditional data such as wordlists gathered from dictionaries. However, using the Web as a corpus brings up several technical and methodological questions, which are dealt with through examples and discussions about the different tools and techniques available. We exemplify our thesis through the study of the suffixal forms: -esque, -este, -able, -ment.
Exploiter des corpus annotés syntaxiquement pour observer le continuum entre arguments et circonstants
Authors: FABRE CÉCILE , BOURIGAULT DIDIER
Published: February 2008

Dans cet article, nous proposons une méthode qui permet de mesurer le degré d'autonomie que manifestent les compléments prépositionnels vis-à-vis du verbe dans un corpus, de manière à tester l'hypothèse couramment admise d'un continuum entre arguments et circonstants et d'en étudier les manifestations. L'exploitation de corpus annotés catégoriellement et syntaxiquement et la mise au point de méthodes de quantification nous permettent de sonder ce continuum en divers points. La méthode met alors au jour des positions médianes, dont nous montrons qu'elles peuvent donner à voir des configurations récurrentes propres au corpus, au comportement intermédiaire entre arguments et circonstants prototypiques.
Five- or six-step scenario for evolution?
Authors: Carter Brandon
Published: February 2008

The prediction that (due to the limited amount of hydrogen available as fuel in the Sun) the future duration of our favourable terrestrial environment will be short (compared with the present age of the Earth) has been interpreted as evidence for a hard-step scenario. This means that some of the essential steps (such as the development of eukaryotes) in the evolution process leading to the ultimate emergence of intelligent life would have been hard, in the sense of being against the odds in the available time, so that they are unlikely to have been achieved in most of the earth-like planets that may one day be discovered in nearby extrasolar systems. It was originally estimated that only one or two of the essential evolutionary steps had to have been hard in this sense, but it has become apparent that this figure may need upward revision, because recent studies of climatic instability suggest that the possible future duration of our biologically favourable environment may be shorter than had been supposed, being only about 1 Gyr rather than 5 Gyr. On the basis of the statistical requirement of roughly equal spacing between hard steps, it is argued that the best fit with the fossil record is now obtainable by postulating the number of hard steps to be five, if our evolution was exclusively terrestrial, or six, if, as now seems very plausible, the first step occurred on Mars.
Determination of intramolecular isotope distribution of ozone by oxidation reaction with silver metal
Authors: Bhattacharya S. K. , Pandey Antra , Savarino J.
Published: February 2008

The intramolecular distribution of 17O in ozone was determined by a new technique using oxidation reaction of ozone with silver and measuring the isotope ratios 18O/16O and 17O/16O of silver oxide, ozone and leftover oxygen. These data along with known 18O distribution in ozone given by Janssen (2005) in terms of r50 = [16O16O18O]/[16O18O16O] allow us to determine r49 = [16O16O17O]/[16O17O16O]. It is seen that r49 values increase from 2.030 to 2.145 with increase of bulk 17O enrichment in ozone from 11.7‰ to 106.3‰ (controlled by varying temperature and pressure during ozone formation) just as r50 values increase from 1.922 to 2.089 with increase in bulk 18O enrichment over the same range. Over bulk enrichment level up to ∼100‰ the r49 values are higher than r50 values by 0.075 ± 0.026. The difference is small but significant since it corresponds to a large change in enrichment values of the asymmetric and symmetric types of 17O16O2 and 18O16O2 relative to a hypothetical ozone standard with statistical isotope distribution. The difference reduces with increase in bulk ozone enrichment. We do not find any significant variation in r values between ozone samples made by Tesla discharge and by UV photolysis of oxygen. Additionally, for ozone samples with negligible enrichment, the symmetrical isotopomers have relatively more heavy isotopes than the asymmetrical ones consistent with their bond strength difference. Atmospheric implications of the results are briefly discussed.
Middle Miocene ice sheet dynamics, deep‐sea temperatures, and carbon cycling: A Southern Ocean perspective
Authors: Shevenell Amelia E. , Kennett James P. , Lea David W.
Published: February 2008

Relative contributions of ice volume and temperature change to the global ∼1‰ δ18O increase at ∼14 Ma are required for understanding feedbacks involved in this major Cenozoic climate transition. A 3‐ma benthic foraminifer Mg/Ca record of Southern Ocean temperatures across the middle Miocene climate transition reveals ∼2 ± 2°C cooling (14.2–13.8 Ma), indicating that ∼70% of the increase relates to ice growth. Seawater δ18O, calculated from Mg/Ca and δ18O, suggests that at ∼15 Ma Antarctica's cryosphere entered an interval of apparent eccentricity‐paced expansion. Glaciations increased in intensity, revealing a central role for internal climate feedbacks. Comparison of ice volume and ocean temperature records with inferred pCO2 levels indicates that middle Miocene cryosphere expansion commenced during an interval of Southern Ocean warmth and low atmospheric pCO2. The Antarctic system appears sensitive to changes in heat/moisture supply when atmospheric pCO2 was low, suggesting the importance of internal feedbacks in this climate transition.
Potential role of the ocean thermostat in determining regional differences in coral reef bleaching events
Authors: Kleypas Joan A. , Danabasoglu Gokhan , Lough Janice M.
Published: February 2008

Several negative feedback mechanisms have been proposed by others to explain the stability of maximum sea surface temperature (SST) in the western Pacific warm pool (WPWP). If these “ocean thermostat” mechanisms effectively suppress warming in the future, then coral reefs in this region should be less exposed to conditions that favor coral reef bleaching. In this study we look for regional differences in reef exposure and sensitivity to increasing SSTs by comparing reported coral reef bleaching events with observed and modeled SSTs of the last fifty years. Coral reefs within or near the WPWP have had fewer reported bleaching events relative to reefs in other regions. Analysis of SST data indicate that the warmest parts of the WPWP have warmed less than elsewhere in the tropical oceans, which supports the existence of thermostat mechanisms that act to depress warming beyond certain temperature thresholds.
Link between benthic oxygen isotopes and magnetic susceptibility in the red‐clay sequence on the Chinese Loess Plateau
Authors: Nie Junsheng , King John W. , Fang Xiaomin
Published: February 2008

Recent rock magnetic work on the red‐clay sequence on the Chinese Loess Plateau (CLP) convincingly demonstrates that the enhancement mechanisms of low‐frequency magnetic susceptibility (i.e., measured at 470 Hz; χlf) in the red‐clay sequence are similar to those in the loess‐paleosol sequence. Therefore, χlf in the red‐clay sequence should indicate precipitation intensity received by the CLP, as is the case in the overlying loess‐paleosol sequence. Based on this result, we compared χlf in the red‐clay sequence with benthic oxygen isotope records. We infer that the primary precipitation source on the CLP varies over time in three phases: during 8.1–4.5 Ma, the East Asian summer monsoon dominates; during 4.5–4 Ma, the Polar Westerlies dominate; during 4–0 Ma, the East Asian summer monsoon dominates. We attribute these precipitation source shifts on the CLP to the closure of the Panama Seaway around 4.5 Ma and the Tibetan uplift during the interval 4–2.6 Ma.
Lability of DOC transported by Alaskan rivers to the Arctic Ocean
Authors: Holmes Robert M. , McClelland James W. , Raymond Peter A. , Frazer Breton B. , Peterson Bruce J. , Stieglitz Marc
Published: February 2008

Arctic rivers transport huge quantities of dissolved organic carbon (DOC) to the Arctic Ocean. The prevailing paradigm is that DOC in arctic rivers is refractory and therefore of little significance for the biogeochemistry of the Arctic Ocean. We show that there is substantial seasonal variability in the lability of DOC transported by Alaskan rivers to the Arctic Ocean: little DOC is lost during incubations of samples collected during summer, but substantial losses (20–40%) occur during incubations of samples collected during the spring freshet when the majority of the annual DOC flux occurs. We speculate that restricting sampling to summer may have biased past studies. If so, then fluvial inputs of DOC to the Arctic Ocean may have a much larger influence on coastal ocean biogeochemistry than previously realized, and reconsideration of the role of terrigenous DOC on carbon, microbial, and food‐web dynamics on the arctic shelf will be warranted.
Multisatellite observation on upwelling after the passage of Typhoon Hai‐Tang in the southern East China Sea
Authors: Chang Yi , Liao Hsiou‐Ting , Lee Ming‐An , Chan Jui‐Wen , Shieh Wei‐Juan , Lee Kuo‐Tien , Wang Guang‐Hua , Lan Yang‐Chi
Published: February 2008

The serial remote sensing based imageries clearly revealed large scale of upwelling within large regional enhancement of chlorophyll‐a (Chl‐a) concentration in the southern East China Sea (ECS) after the passage of super typhoon Hai‐Tang in July 2005. After the typhoon on 22 July, the upwelling area (<26°C) expanded rapidly to 9146 km2 on the shelf‐break. The large increased upwelling persisted for more than a week. Ocean color images also reveled that high Chl‐a concentration of >3.0 mg/m3 appeared in the shelf region, where the high Chl‐a pattern matched the upwelling in terms of location and time. On the other hand, a large offshore SST cooling was also observed mainly to the right of typhoon track on 20 July, it lasted in a period of 2–3 days. This paper provides clear and high‐resolution evidence that typhoon significant increased upwelling and Chl‐a concentration in the southern ECS.
Reptin and Pontin function antagonistically with PcG and TrxG complexes to mediate Hox gene control
Authors: Diop Soda Balla , Bertaux Karine , Vasanthi Dasari , Sarkeshik Ali , Goirand Benjamin , Aragnol Denise , Tolwinski Nicholas S , Cole Michael D , Pradel Jacques , Yates John R , Mishra Rakesh K , Graba Yacine , Saurin Andrew J
Published: February 2008

Pontin (Pont) and Reptin (Rept) are paralogous ATPases that are evolutionarily conserved from yeast to human. They are recruited in multiprotein complexes that function in various aspects of DNA metabolism. They are essential for viability and have antagonistic roles in tissue growth, cell signalling and regulation of the tumour metastasis suppressor gene, KAI1, indicating that the balance of Pont and Rept regulates epigenetic programmes critical for development and cancer progression. Here, we describe Pont and Rept as antagonistic mediators of Drosophila Hox gene transcription, functioning with Polycomb group (PcG) and Trithorax group proteins to maintain correct patterns of expression. We show that Rept is a component of the PRC1 PcG complex, whereas Pont purifies with the Brahma complex. Furthermore, the enzymatic functions of Rept and Pont are indispensable for maintaining Hox gene expression states, highlighting the importance of these two antagonistic factors in transcriptional output.
Angiogenic inhibitor protein fractions derived from shark cartilage
Authors: Bargahi Afshar , Rabbani-Chadegani Azra
Published: February 2008

Development of therapies based on the growth inhibition of new blood vessels is among the most intensively studied approaches to the treatment of cancer and other angiogenesis-related diseases. Shark cartilage has been proven to have inhibitory effects on the endothelial cell angiogenesis, metastasis, cell adhesion and MMP (matrix metalloprotease) activity. In the present study, we have used a chromatography-based procedure for the isolation and partial purification of a shark cartilage protein fraction containing anti-angiogenesis activity. Proteins were extracted in 4 M guanidinium chloride, followed by sequential anion- and cation-exchange column chromatography. Angiogenesis assays were performed using the rat aortic ring and chick CAM (chorioallantoic membrane) assay models. The results show that the final fraction contains two proteins with molecular masses of 14.7 and 16 kDa. The protein fraction is able to block microvessel sprouting in the collagen-embedded rat aortic ring assay in vitro and inhibition of capillary sprouting in the CAM assay in vivo. It is suggested that these are partially purified anti-angiogenesis proteins, which have further biotechnological or biomedical applications.
Compact magnetic quadrupole triplet for a low-energy high-current ion beam transport
Authors: Cho Yong-Sub , Kim Han-Sung , Kwon Hyeok-Jung
Published: February 2008

It is a difficult task to design a conventional quadrupole triplet as compact and simple as solenoids for high-current ion beam transport. In the design of a quadrupole triplet presented here, we installed three poles with the same orientation on a yoke and these were excited using two coils located between poles. This new design allows the easier fabrication of a compact quadrupole triplet compared to the conventional design. Simple equations for the preliminary design were obtained. A prototype with an aperture radius of 55mm and a focusing power of 3.3m−1 for 50keV proton beams was designed, fabricated, and tested. The measured field profile agreed well with the calculated profile. The length of the compact magnetic quadrupole triplet was comparable with a solenoid, and its electrical power consumption was about 40% that of a solenoid.
The MAXEBIS at GSI as a test ion source for charge breeding and for HITRAP
Authors: Kester O. , Becker R. , Pfister J. , Sokolov A. , Vorobjev G. , Vogel M. , Winters D. , Zimmermann H.
Published: February 2008

The electron beam ion source MAXEBIS, developed and built at the University of Frankfurt, has been installed at GSI to serve as an offline test ion source for the HITRAP project and for use as a test setup for charge breeding explorations. The setup has been equipped with new diagnostics and beam optics devices. Two ion sources dedicated to the production of singly charged ions for external ion injection into the MAXEBIS have been included. First time of flight (TOF) spectra with external injected, charge-bred argon ions were taken. However, these spectra indicated beam losses in the beam transport from the multipassage spectrometer (MPS) to the MAXEBIS. In order to understand the losses, the beam transport has been simulated with the SIMION code and the beam line has been modified accordingly. Measurements of the MAXEBIS’ beam emittance, using the “nondestructive” beam profile method, have been performed as well as measurements of the electron current density via charge state analysis of the TOF spectra. The injection and breeding efficiency of the MAXEBIS have been determined for the first time. The results of the measurements and the planned experiments will be discussed.
Valence transitions of Br2 in Ar matrices: Interaction with the lattice and predissociation
Authors: Ibrahim Heide , Gühr Markus , Schwentner Nikolaus
Published: February 2008

Fluorescence spectra from v′=0 of the B, A and A′ states of Br2∕Ar are presented for excitation wavelengths from 630to540nm with high resolution, to evaluate isotopic splittings in emission and absorption. The observed progression of sharp zero phonon lines (ZPLs) from v′=2 to v′=19 in B excitation is used to derive spectroscopic constants. The ZPL broadening and the growing phonon sideband (PSB) contributions indicate an increase of matrix influence on the X-B transition with rising v′. Contributions of the PSB are parameterized with the Huang-Rhys coupling constant S, where S=1 near the potential minimum reflects the electron-phonon coupling and S=4 close to Franck-Condon maximum originates from vibrational coupling. The PSB spectral composition correlates with the matrix phonon density of states, and the ZPL broadens and shifts with temperature. Two crossings with repulsive states (between v′=4–5 and v′=7–9) leading to matrix induced predissociation and a third tentative one between v′=14 and 15 are indicated by ZPL broadening, population flow, and spectral shifts. The crossing energies are close to gas phase and matrix calculations. The stepwise flow of intensity from B via repulsive states to A′ and, similarly, from the A continuum to A′ is discussed. Emission quantum efficiency of the B state decreases from near unity at v′=0 to less than 10−3 at v′=19. Broadening of ZPL near crossings yields predissociation times of 5 and 2.5ps corresponding to probabilities of 5% and 10% per round-trip for the two lowest crossings, respectively.
Electrodynamics and the Gauss linking integral on the 3-sphere and in hyperbolic 3-space
Authors: DeTurck Dennis , Gluck Herman
Published: February 2008

In this first of two papers, we develop a steady-state version of classical electrodynamics on the 3-sphere and in hyperbolic 3-space, including an explicit formula for the vector-valued Green’s operator, an explicit formula of Biot–Savart type for the magnetic field, and a corresponding Ampere’s law contained in Maxwell’s equations. We then use this to obtain explicit integral formulas for the linking number of two disjoint closed curves in these spaces. These formulas, like their prototypes in Euclidean 3-space, are geometric rather than just topological because their integrands are invariant under orientation-preserving isometries of the ambient space. In the second paper, we obtain integral formulas for twisting, writhing, and helicity and prove the theorem LINK=TWIST+WRITHE in the 3-sphere and in hyperbolic 3-space. We then use these results to derive upper bounds for the helicity of vector fields and lower bounds for the first eigenvalue of the curl operator on subdomains of these two spaces. An announcement of most of these results and a hint of their proofs can be found in e-print arXiv:math.GT/0406276, while an expanded version of this paper, containing many details which are here left to the reader, can be found at e-print arXiv:math.GT/0510388.
Hydration free energy of a Model Lennard-Jones solute particle: Microscopic Monte Carlo simulation studies, and interpretation based on mesoscopic models
Authors: Gruziel Magdalena , Rudnicki Witold R. , Lesyng Bogdan
Published: February 2008

In this study, the hydration of a model Lennard-Jones solute particle and the analytical approximations of the free energy of hydration as functions of solute microscopic parameters are analyzed. The control parameters of the solute particle are the charge, the Lennard-Jones diameter, and also the potential well depth. The obtained multivariate free energy functions of hydration were parametrized based on Metropolis Monte Carlo simulations in the extended NpT ensemble, and interpreted based on mesoscopic solvation models proposed by Gallicchio and Levy [J. Comput. Chem. 25, 479 (2004)], and Wagoner and Baker [Proc. Natl. Acad. Sci. U.S.A. 103, 8331 (2006)]. Regarding the charge and the solute diameter, the dependence of the free energy on these parameters is in qualitative agreement with former studies. The role of the third parameter, the potential well depth not previously considered, appeared to be significant for sufficiently precise bivariate solvation free energy fits. The free energy fits for cations and neutral solute particles were merged, resulting in a compact manifold of the free energy of solvation. The free energy of hydration for anions forms two separate manifolds, which most likely results from an abrupt change of the coordination number when changing the size of the anion particle.
Nonstatistical spin dynamics in photodissociation of H2O at 157nm
Authors: Lu I-Chung , Wang Fengyan , Yuan Kaijun , Cheng Yuan , Yang Xueming
Published: February 2008

Photodissociation of H2O via the A band at 157nm has been reinvestigated using the high resolution H atom Rydberg tagging technique. The spin-orbit population distributions were found to be highly nonstatistical for the OH(v=0,1,2) product channels, while nearly statistical for the OH(v=4) channel. These results suggest that the dissociation dynamics of H2O at 157nm is remarkably different for different vibrationally excited OH channels. The result presented here is not entirely consistent with the direct dynamical picture of the A band dissociation of H2O.
Carbynes phonons: A tight binding force field
Authors: Milani Alberto , Tommasini Matteo , Zerbi Giuseppe
Published: February 2008

Modeling the vibrational structure of linear carbon chains has proved to be a difficult task with present first-principles calculations. This limits their applicability for the interpretation of experimental data, such as Raman scattering experiments on linear carbon chains within nanotubes. These limitations can be overcome by means of a simple tight binding scheme for π-electrons. In this work a force field for the calculation of longitudinal phonon dispersion branches is built on the basis of bond-bond polarizabilities and just three parameters. The so obtained phonon dispersion branches are in very good agreement with the experimental data on carbynes in different environments and polyynes of any length. The model is discussed in relation to the importance of long range vibrational interactions in carbynes. The physical phenomena affecting their vibrational properties (i.e., Kohn anomaly, electron-phonon coupling) can be accurately and analytically described by the present approach.
Dynamic nuclear polarization at high magnetic fields
Authors: Maly Thorsten , Debelouchina Galia T. , Bajaj Vikram S. , Hu Kan-Nian , Joo Chan-Gyu , Mak–Jurkauskas Melody L. , Sirigiri Jagadishwar R. , van der Wel Patrick C. A. , Herzfeld Judith , Temkin Richard J. , Griffin Robert G.
Published: February 2008

Dynamic nuclear polarization (DNP) is a method that permits NMR signal intensities of solids and liquids to be enhanced significantly, and is therefore potentially an important tool in structural and mechanistic studies of biologically relevant molecules. During a DNP experiment, the large polarization of an exogeneous or endogeneous unpaired electron is transferred to the nuclei of interest (I) by microwave (μw) irradiation of the sample. The maximum theoretical enhancement achievable is given by the gyromagnetic ratios (γe∕γl), being ∼660 for protons. In the early 1950s, the DNP phenomenon was demonstrated experimentally, and intensively investigated in the following four decades, primarily at low magnetic fields. This review focuses on recent developments in the field of DNP with a special emphasis on work done at high magnetic fields (⩾5T), the regime where contemporary NMR experiments are performed. After a brief historical survey, we present a review of the classical continuous wave (cw) DNP mechanisms—the Overhauser effect, the solid effect, the cross effect, and thermal mixing. A special section is devoted to the theory of coherent polarization transfer mechanisms, since they are potentially more efficient at high fields than classical polarization schemes. The implementation of DNP at high magnetic fields has required the development and improvement of new and existing instrumentation. Therefore, we also review some recent developments in μw and probe technology, followed by an overview of DNP applications in biological solids and liquids. Finally, we outline some possible areas for future developments.
Reduced efficiency roll-off in high-efficiency hybrid white organic light-emitting diodes
Authors: Schwartz Gregor , Reineke Sebastian , Walzer Karsten , Leo Karl
Published: February 2008

White organic light emitting diodes harvesting triplet excitons from the fluorescent blue emitter N,N′-di-1-naphthalenyl-N,N′-diphenyl-[1,1′:4′,1″:4″,1‴-quaterphenyl]-4,4‴-diamine (4P-NPD) are presented. Direct doping of the phosphorescent orange iridium(III)bis(2-methyldibenzo-[f,h]quinoxaline)(acetylacetonate) into 4P-NPD results in a strongly reduced efficiency roll-off as compared to separate emission layers, and yields 49.3lmW−1 total external power efficiency (24.1% quantum efficiency) at a luminance of 1000cdm−2 [CIE 1931 chromaticity coordinates (0.49,0.41)], measured in an integrating sphere. Introduction of an exciton balancing interlayer improves the chromaticity (0.43,0.43) toward the CIE illuminant A warm white point and keeps a high efficiency of 40.7lmW−1, 20.3%.
Bowing of the band gap pressure coefficient in InxGa1−xN alloys
Authors: Franssen G. , Gorczyca I. , Suski T. , Kamińska A. , Pereiro J. , Muñoz E. , Iliopoulos E. , Georgakilas A. , Che S. B. , Ishitani Y. , Yoshikawa A. , Christensen N. E. , Svane A.
Published: February 2008

The hydrostatic pressure dependence of photoluminescence, dEPL/dp, of InxGa1−xN epilayers has been measured in the full composition range 0<x<1. Furthermore, ab initio calculations of the band gap pressure coefficient dEG/dp were performed. Both the experimental dEPL/dp values and calculated dEG/dp results show pronounced bowing and we find that the pressure coefficients have a nearly constant value of about 25 meV/GPa for epilayers with x>0.4 and a relatively steep dependence for x<0.4. On the basis of the agreement of the observed PL pressure coefficient with our calculations, we confirm that band-to-band recombination processes are responsible for PL emission and that no localized states are involved. Moreover, the good agreement between the experimentally determined dEPL/dp and the theoretical curve of dEG/dp indicates that the hydrostatic pressure dependence of PL measurements can be used to quantify changes of the band gap of the InGaN ternary alloy under pressure, demonstrating that the disorder-related Stokes shift in InGaN does not induce a significant difference between dEPL/dp and dEG/dp. This information is highly relevant for the correct analysis of pressure measurements.
Effect of nitrogen incorporation on 1/f noise performance of metal-oxide-semiconductor field effect transistors with HfSiON dielectric
Authors: Shahriar Rahman M. , Morshed Tanvir , Devireddy S. P. , Çelik-Butler Zeynep , Quevedo-Lopez M. A. , Shanware A. , Colombo L.
Published: February 2008

Nitrided hafnium silicate is the leading candidate for possible replacement of SiON as a gate dielectric. 1/f noise characteristics of plasma and thermally nitrided Hf-based high-dielectric constant (high-k) gate dielectrics were investigated. Plasma nitrided samples showed less noise than thermally nitrided samples. The mobility fluctuation component of 1/f noise was found to show a strong process dependence, specifically on the nitridation technique. Increase in the number of Coulomb scattering sites due to the additional Si–N bonds near the high-k/Si interface is suggested as the reason for this dependence. This work represents the first investigation on the effect of different nitridation methodologies on low-frequency noise mechanisms in ultrathin (∼2 nm) Hf-based high-k nMOSFET (metal-oxide-semiconductor field effect transistor).
Magnetization reversal of Ga1−xMnxAs layers separated by a nonmagnetic spacer
Authors: Kirby B. J. , Borchers J. A. , Liu X. , Ge Z. , Cho Y. J. , Dobrowolska M. , Furdyna J. K.
Published: February 2008

We have used polarized neutron reflectometry to individually examine the magnetization reversals of ferromagnetic Ga1−xMnxAs layers separated by a nonmagnetic GaAs spacer layer of varying thickness. For each of the samples studied, the top Ga1−xMnxAs layer is adjacent to a Be-doped Al0.25Ga0.75As capping layer on one side and the GaAs spacer on the other, while the bottom Ga1−xMnxAs layer is surrounded by GaAs on either side. For samples with spacer thicknesses of 12 and 6nm, antiparallel alignment of the two Ga1−xMnxAs layer magnetizations was observed at multiple fields, implying that hole doping from the capping layer strongly affects the coercivity of the top Ga1−xMnxAs layer but has a weaker effect on the coercivity of the bottom Ga1−xMnxAs layer. However, for a spacer thickness of 3nm, both top and bottom Ga1−xMnxAs layers appear to be equally influenced by the capping layer, as virtually identical coercivities were observed. This behavior is evidence of coupling between the Ga1−xMnxAs layers across the 3nm GaAs spacer.
Temperature evolution of lattice strains in relaxor PbSc1∕2Nb1∕2O3 thin films
Authors: Janolin Pierre-Eymeric , Kiat Jean-Michel , Malibert Charlotte , Asanuma Shutaro , Uesu Yoshiaki
Published: February 2008

Temperature evolution of the lattice parameters of relaxor PbSc1∕2Nb1∕2O3 (PSN) thin films have been measured and compared to the evolution of bulk PSN. In PSN films, a room temperature tetragonal polar phase transforms at higher temperature into a nonpolar tetragonal phase. Critical and Burns temperatures, associated, respectively, to the onset of the ferroelectric phase and to the nucleation of polar nanoregions have been assigned from strong anomalies in the temperature evolution of the film. These complex behaviors are explained by a quantitative study of the strains lying in the film.
Nonlinear viscoresistive dynamics of the m=1 tearing instability
Authors: Takeda K. , Agullo O. , Benkadda S. , Sen A. , Bian N. , Garbet X.
Published: February 2008

A numerical investigation of the viscoresistive evolution of the m=1 tearing instability is presented. Its linear growth rate is found to have various power law scalings in different viscoresistive regimes, in agreement with the theoretical results of Porcelli [Phys. Fluids 30, 1734 (1987)]. Our principal focus is on the nonlinear behavior of this instability at a high value of the stability parameter Δ′ and for different values of the Prandtl number Pm. It is found that, depending on the Prandtl regime, and in association with a poloidal oscillation of the magnetic structure, a quadrupolar flow can be generated and/or destroyed outside the current sheet. The reconnection process appears to be influenced by the generation/inhibition dynamics of this external quadrupolar flow. At large enough times, this nonlinear quadrupolar flow can be partially advected in the poloidal direction at the Alfvén velocity. However at high Pm values, such an advection is inhibited by viscosity and, as a consequence, the latter contributes to the reduction of the amplitude of the poloidal oscillations.
Broad forbidden bands in parallel-coupled locally resonant ultrasonic metamaterials
Authors: Cheng Y. , Xu J. Y. , Liu X. J.
Published: February 2008

The authors demonstrate that a class of ultrasonic metamaterial, which is composed of subwavelength resonant units built up by parallel-coupled Helmholtz resonators with identical resonant frequency, possesses broad locally resonant forbidden bands. The bandwidths are strongly dependent on the number of resonators in each unit. The broadening of bands is ascribed to the change of effective acoustic impendence. The coupling effects on the wave vector and negative dynamic modulus are discussed. Numerical simulations by finite element method further confirm the theoretical results.
Control of surface plasmon generation efficiency by slit-width tuning
Authors: Kihm H. W. , Lee K. G. , Kim D. S. , Kang J. H. , Park Q-Han
Published: February 2008

We demonstrate control of surface plasmon polariton (SPP) generation efficiency via varying the width of a single slit that acts as a SPP launcher. Generated SPP intensities are directly measured through a near-field scanning microscope measuring both the transmitted and the scattered light. These results demonstrate enhancement as well as suppression of surface plasmon generation efficiency at specific slit widths. The experimentally observed sinusoidal width dependence can be explained by diffraction theory.
Uniformity of internal linear-type inductively coupled plasma source for flat panel display processing
Authors: Lim Jong Hyeuk , Kim Kyong Nam , Park Jung Kyun , Lim Jong Tae , Yeom Geun Young
Published: February 2008

The variation in plasma uniformity over an extremely large size inductively coupled plasma (ICP) source of 2750×2350mm2 was examined. An internal linear-type antenna called “double comb-type antenna” was used as the ICP source. A plasma density of ∼1.4×1011∕cm3 could be obtained at 5mTorr Ar by applying 10kW rf power to the source at a frequency of 13.56MHz. An increase in rf power from 1to10kW improved the plasma uniformity over a substrate area of 2300×2000mm2 from 18.1% to 11.4%. The improvement in uniformity of the internal ICP source was attributed to the increase in plasma density near the wall.
Thermally stable amorphous (AlMoNbSiTaTiVZr)50N50 nitride film as diffusion barrier in copper metallization
Authors: Tsai Ming-Hung , Wang Chun-Wen , Lai Chia-Han , Yeh Jien-Wei , Gan Jon-Yiew
Published: February 2008

Results on copper metallization diffusion barriers using high-entropy alloy (HEA) nitride are reported. The HEA nitride (AlMoNbSiTaTiVZr)50N50 is amorphous in the as-deposited state and remains its noncrystallinity up to a high temperature of 850°C. To evaluate its diffusion barrier characteristics, Cu∕(AlMoNbSiTaTiVZr)50N50∕Si test structures were prepared and annealed under 750–900°C for 30min. The results show that the current nitride prevents the reaction between Cu and Si before its failure at 900°C. The outstanding barrier performance and high thermal stability of amorphous structure are suggested to originate from multiprincipal-element effects.
A constructive combination of antireflection and intermediate-reflector layers for a-Si∕μc-Si thin film solar cells
Authors: Das Chandan , Lambertz Andreas , Huepkes Juergen , Reetz Wilfried , Finger Friedhelm
Published: February 2008

This device design approach combines sputter-deposited TiO2 antireflection layer (ARL) and plasma-enhanced chemical vapor deposition-grown SiOx intermediate-reflector layer (IRL) in superstrate a-Si∕μc-Si thin film solar cell. The loss of current from either the component cells with individual application of ARL and IRL has been recovered with their combined application. With both ARL and IRL in a-Si∕μc-Si cell, (a) the top cell current and (b) the sum of top and bottom cell current increases. An initial efficiency of 11.8% [Voc=1.42V, FF=0.74, Jsc (top)=11.5mAcm−2, Jsc (bottom)=11.2mAcm−2] is achieved from such an a-Si∕μc-Si cell with a total Si layer thickness less than 2μm.
High-speed deformation of soft lithographic nanograting patterns for ultrasensitive optical spectroscopy
Authors: Truxal Steven C. , Tung Yi-Chung , Kurabayashi Katsuo
Published: February 2008

We demonstrate a spectroscopy technique that implements a high-speed tunable grating to take spectroscopy measurements with a single, extremely sensitive photodetector. The tunable grating consists of a transparent elastomer microbridge soft lithographically patterned and assembled onto silicon microactuators. We show the ability to track the optical spectrum of time-varying multiwavelength signals with a 500μs time resolution and sensitivity capable of detecting optical powers near 36pW. Such a level of sensitivity is suitable for detecting the spectral fluorescence of low concentration dyes, microbeads, or quantum dots.