bluuebunny/crossref_metadata_2025 huggingface dataset:
Posttraumatic growth in cancer patients and partners—effects of role, gender and the dyad on couples' posttraumatic growth experience
Authors: Zwahlen Diana , Hagenbuch Niels , Carley Margaret I. , Jenewein Josef , Buchi Stefan
Published: April 2009

Background/Aim: Little is known about factors influencing positive effects in couples facing a cancer diagnosis.

Methods: A heterogeneous sample of 224 couples from a multi‐site study (four oncology units) completed questionnaire surveys including the Posttraumatic Growth Inventory (PTGI) as a measure of positive psychological effects.

Results: The data demonstrated that all three investigated factors—gender, role (patient vs partner) and the dyad (belonging to any of the 224 couples)—significantly contributed to variation in PTGI total scores and subscales. Variability between couples (factor dyad) appeared stronger than variability between patient and partner participants (factor role) and between male and female participants (factor gender). Role and gender analysis showed that patients demonstrated higher levels of posttraumatic growth than partners; and female participants scored higher on PTGI than males. Male patient–female partner pairs show greater association in their experience of posttraumatic growth than female patient–male partner pairs. Correlations also suggested that, regardless of the gender and role composition, patients and partners may experience parallel growth.

Conclusions: Our findings indicate that positive psychological experiences may be shared by partners affected by cancer in similar ways as have been shown for negative psychological effects. Intra‐couple similarities or processes may have a more important function in experiencing benefits than factors like gender or being the patient or the partner. These results underline the importance of a family approach to understanding negative and positive psychological effects of cancer. Copyright © 2009 John Wiley & Sons, Ltd.
Psychometric qualities of the Dutch version of the Pediatric Inventory for Parents (PIP): a multi‐center study
Authors: Vrijmoet‐Wiersma C. M. Jantien , Hoekstra‐Weebers Josette E. H. M. , Margreet de Peinder W. M. G. , Koopman Hendrik M. , Tissing Wim J. E. , Treffers Philip D. A. , Bierings Marc B. , Jansen Nathalie C. A. , Grootenhuis Martha A. , Egeler R. Maarten
Published: April 2009

Objectives: Diagnosis and treatment of childhood cancer are continuous stressors in the lives of the entire family involved. Disease‐related tools for the assessment of parental stress and adaptation are scarce. For that reason, the Pediatric Inventory for Parents (PIP), a disease‐related measure, was translated into Dutch and its psychometric qualities were determined to prove its value.

Methods: The PIP and three other measures (State‐Trait Anxiety Inventory, General Health Questionnaire and Parenting Stress Index, Short Form) were administered to 174 parents of 107 children diagnosed with cancer in three university medical centers in the Netherlands.

Results: Internal consistency (Crohnbach's α=0.94 and 0.95) and test–retest reliability (Pearson's r between 0.67 and 0.87) of the Dutch PIP total scales are satisfactory. Validity was illustrated by a high correlation between PIP‐scores and anxiety and general stress. Confirmatory factor analysis showed acceptable fit to the data for the original four‐factor and the one‐factor models; the four‐factor model showed slightly better fit.

Conclusion: The PIP can be used in clinical practice to assess disease‐related parental stress. Further psychometric testing is highly recommended. Copyright © 2009 John Wiley & Sons, Ltd.
Thymosin β4 is differentially expressed in the cerebrospinal fluid of Creutzfeldt‐Jakob disease patients: a MALDI‐TOF MS protein profiling study
Authors: Qualtieri Antonio , Urso Elena , Le Pera Maria , Bossio Sabrina , Bernaudo Francesca , Ferraro Tiziana , Crescibene Lucia , Aguglia Umberto , Quattrone Aldo
Published: April 2009

MALDI‐TOF protein profiling analysis permits the detection of peptides and small proteins in complex protein mixtures with great accuracy. We applied this analysis to cerebrospinal fluid (CSF) from 15 patients affected by Creutzfeldt‐Jakob disease (CJD). We compared the levels of the normalized ion signals of 11 sporadic and 4 genetic CJD forms with those from ten healthy control subjects and eight non‐CJD relapsing‐remitting multiple sclerosis patients. In so doing, we detected 61 differentially expressed ion signals in CJD samples compared to controls. Among the 61 signals, 3 signals had significantly increased levels with high statistical significance (p <0.0001) and were located at 3238.3 m/z, 4963.7 m/z, and 8565.3 m/z. We characterized the 5.0 and 8.6 kDa proteins as thymosin β4 N‐acetylated and free ubiquitin, respectively, while the 3.2‐kDa peptide remained uncharacterized. Although elevated ubiquitin levels have previously been described in CJD, we have demonstrated for the first time the involvement of thymosin β4 in a neurodegenerative disease. To support the validity of thymosin β4 levels obtained by MALDI‐TOF analysis, an independent enzyme immunoassay analysis was performed. Moreover, a validation cohort consisting of CSF from three CJD patients, five healthy subjects, and six non‐CJD relapsing‐remitting multiple sclerosis patients was analyzed in a similar way, yielding superimposable results. We propose that thymosin β4 is a potential new candidate marker for the ante mortem diagnosis of CJD disease.
Changes of serum‐associated fucosylated glycoproteins and changes in glycosylation of IgA in human cirrhosis
Authors: Carré Yoann , Klein André , Mathurin Philippe , Michalski Jean‐Claude , Morelle Willy
Published: April 2009

Many modifications in N‐glycosylation have been demonstrated in hepatic cirrhosis. These modifications correspond to an increase of a bisecting core alpha(1,6)‐fucosylated biantennary glycan, an increase in core fucosylation, and the presence of an important population of neutral oligosaccharides in human serum of cirrhotic patients. In this study, a glycoproteomic approach which consists of lectin affinity chromatography, MALDI‐TOF MS for the characterization of N‐glycans released from glycoproteins, one‐ and 2‐D PAGE, electrospray ionization quadrupole ion trap (ESI‐QIT) MS was used to identify serum fucosylated glycoproteins related to cirrhosis. Employing this method, we have shown that IgA is one of the major proteins that is responsible of the glycosylation modifications observed in the serum N‐glycome of cirrhotic patients. To our knowledge, this is the first time that aberrant N‐glycosylation of IgA in cirrhosis is described.
Studies on an Improved Plastic Bonded Explosive (PBX) for Shaped Charges
Authors: Samudre Samson S. , Nair Ushadevi R. , Gore Girish M. , Kumar Sinha Rabindra , Kanti Sikder Arun , Nandan Asthana Shri
Published: April 2009

This paper reports the characteristics and performance evaluation of a pressed plastic bonded explosive (PBX) composition based on hexanitrohexaazaisowurtzitane (HNIW, CL‐20) and polyurethane (PU) in comparison with PU‐coated cyclotetramethylene tetranitramine (HMX). PU‐coated compositions were prepared by slurry method. The processed CL‐20‐based composition exhibited a relatively higher sensitivity compared to that of the HMX composition. The measured velocity of detonation (VOD) of the CL‐20‐based composition was found to be higher than predicted. A theoretical approach was applied to assess the penetration capability of the CL‐20 formulation. Shaped charges of 32 mm caliber were prepared and penetration experiments were carried out at 37 mm standoff distance on mild steel blocks. The results established high penetration capability of CL‐20‐based formulation. An attempt was made to explain the trends obtained.
Dielectric dispersion study of Mn‐doped PLZT (8/65/35)
Authors: Mohiddon Md. Ahamad , Yadav K. L.
Published: April 2009

Mn‐modified Pb0.92La0.08(Zr0.65Ti0.35)O3 (PLZT) was prepared chemically by a coprecipitate method using their respective nitrate salts and isopropoxides. Differential thermal analysis (DTA) and X‐ray analysis clearly show the formation of PLZT single rhombohedral phase for samples calcined beyond 750 °C. Uniform grain distribution was observed from scanning electron microscopic (SEM) studies and grain size was found to increase with Mn doping up to x = 0.08 and then decreased. Dielectric measurement shows the decrease in peak transition temperature (TC) with Mn doping up to x = 0.12 and then increase along with a sharp rise in dielectric maxima. A diffuse dielectric dispersion is observed in all the compositions. A detailed dispersion study was carried out using the Vogel–Fulcher empirical relation, a universal relaxation law and the Havriliak–Negami function. The Vogel–Fulcher relation fitting parameters of activation energy and freezing temperature were found to decrease with Mn doping up to x = 0.12, which was expected to be the cause of the variation of TC. The exponent m of the universal relaxation law was found to increase with Mn doping and also with increasing temperature, which suggests an enhanced conducting nature of the composition. In the Havriliak–Negami function, the Cole–Cole fitting parameter α was found to increase and β was found to decrease with Mn doping and also with temperature, which suggests that the dispersion behavior changed from Cole–Cole type to Cole–Davidson type with Mn doping in PLZT. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Luminescence and structural properties of oxyorthosilicate and Al2O3 nanophosphors
Authors: Blair Michael W. , Jacobsohn Luiz G. , Bennett Bryan L. , Tornga Stephanie C. , Yukihara Eduardo G. , McKigney Edward A. , Muenchausen Ross E.
Published: April 2009

A large amount of research has been conducted on semiconducting quantum dots exploring quantum confinement effects. On the other hand, nanophosphors – inorganic insulating nanostructured luminescent materials – have received considerably less attention. Our research involving nanomaterials has then focused on the question: How does reduced dimensionality affect the physical and chemical behaviour of nanophosphors? In order to partially answer this fundamental question, we have produced numerous oxides, among them Lu2SiO5:Ce (LSO), Y2SiO5:Ce (YSO), Gd2SIO5:Ce (GSO), and Al2O3, and characterized their structural and luminescent properties. Structure, grain size, phase purity and crystallite morphology were determined using X‐ray diffraction, transmission electron microscopy, and electron paramagnetic resonance. The luminescent properties of the nanophosphors were characterized by thermoluminescence, radioluminescence, photoluminescence, and optically stimulated luminescence. In this work, we will present an overview of the field of nanophosphors, and summarize the results obtained in our laboratory with particular emphasis on the luminescent properties. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Accounting for regression‐to‐the‐mean in tests for recent changes in institutional performance: Analysis and power
Authors: Jones Hayley E. , Spiegelhalter David J.
Published: April 2009

Recent changes in individual units are often of interest when monitoring and assessing the performance of healthcare providers. We consider three high profile examples: (a) annual teenage pregnancy rates in English local authorities, (b) quarterly rates of the hospital‐acquired infection Clostridium difficile in National Health Service (NHS) Trusts and (c) annual mortality rates following heart surgery in New York State hospitals. Increasingly, government targets call for continual improvements, in each individual provider as well as overall.

Owing to the well‐known statistical phenomenon of regression‐to‐the‐mean, observed changes between just two measurements are potentially misleading. This problem has received much attention in other areas, but there is a need for guidelines within performance monitoring.

In this paper we show theoretically and with worked examples that a simple random effects predictive distribution can be used to ‘correct’ for the potentially undesirable consequences of regression‐to‐the‐mean on a test for individual change. We discuss connections to the literature in other fields, and build upon this, in particular by examining the effect of the correction on the power to detect genuine changes. It is demonstrated that a gain in average power can be expected, but that this gain is only very slight if the providers are very different from one another, for example due to poor risk adjustment. Further, the power of the corrected test depends on the provider's baseline rate and, although large gains can be expected for some providers, this is at the cost of some power to detect real changes in others. Copyright © 2009 John Wiley & Sons, Ltd.
Eine Methode zur Bewertung von Restspalten in Schweißnähten an T‐ und Kreuzstoßverbindungen
Authors: Feldmann Markus , Eichler Björn , Höhler Susanne
Published: April 2009

Eingeführte Normen verlangen von der Stahlbaufertigung den Nachweis einer vollständigen Durchschweißung bei Vollanschlüssen. Für die ausführenden Betriebe ist diese Forderung oft mit zeit‐ und kostenintensiven Reparaturschweißungen versehen.

Bis vor kurzem fehlte eine Methode zur Klassifizierung und damit einhergehend eine Methode zur Tolerierung von nicht vollständigen Durchschweißungen (Restspalte), so dass teure Reparaturarbeiten vorprogrammiert waren.

Im Rahmen eines von der Arbeitsgemeinschaft industrieller Forschungsvereinigungen AiF über den Deutschen Ausschuss für Stahlbau DASt geförderten Projektes [1] wurde die Grundlage eines Beurteilungskonzeptes geschaffen, das bei hinreichend genauer Detektierung eines Restspaltes durch ein zerstörungsfreies Prüfverfahren und unter Einhaltung der im Stahlbau geforderten Bauteilsicherheit gewährleistet, dass eine nach aktueller Normensituation ungenügende Durchschweißung im Bauteil belassen werden kann. Mit Hilfe bruchmechanischer Methoden kann so für nicht vollständig durchschweißte HY‐ bzw. DHY‐Nähte an Kreuz‐ und T‐Stößen eine ausreichende Tragfähigkeit nachgewiesen und sprödes Versagen der Verbindung ausgeschlossen werden, und zwar sowohl für ruhende als auch für zyklische Beanspruchungen.
Zuschriften zu: Naumes, J., Strohmann, I., Ungermann, D., Sedlacek, G.: Die neuen Stabilitätsnachweise im Stahlbau nach Eurocode 3
Authors: Naumes Johannes , Strohmann Isabel , Ungermann Dieter , Sedlacek Gerhard
Published: April 2009

[Stahlbau 77 (2008), H. 10, S. 748–761 ]
Zuschriften zu: Kurrer K.‐E.: Genius loci des Stahlbaus: Mainz, Gustavsburg und der deutsche Stahlbautag 2008
Authors: Kurrer Karl‐Eugen
Published: April 2009

[Stahlbau 78 (2009), H. 2, S. 108–123 ]
Short soft x‐ray sources
Authors: Siciliano M.V. , Lorusso A. , Velardi L. , Nassisi V.
Published: April 2009

In this work we report on the characterization of pulsed soft x‐rays emitted from laser‐produced plasma. The plasma was generated by a pulsed KrF excimer laser focused on pure Si, Cu and Ta targets by 40, 80 and 120 mJ laser energies. The utilized detector was a very sensitive Faraday cup which opportunely biased was able to record time‐resolved signals of x‐rays and to estimate their energy. The found x‐rays energy values were compared with the ion temperature of the plasma obtained by fitting the time‐resolved ion current signals with a shifted Maxwell‐Boltzmann velocity distribution. The results showed that the laser‐produced Ta plasma induced bunches of x‐rays having in average the highest energy values and it was also characterized by ion temperature higher than the ones of the laser‐produced Si and Cu plasmas. Copyright © 2009 John Wiley & Sons, Ltd.
Practitioner expertise: Creating quality within the daily tumble of events in youth settings
Authors: Larson Reed W. , Rickman Aimee N. , Gibbons Colleen M. , Walker Kathrin C.
Published: April 2009

Practitioners in youth settings experience life on the ground as a tumble of events, shaped by a confluence of youth needs, institutional expectations, and other inputs. The quality of the setting is determined in part by practitioners' expertise in shaping and responding to these events. The situations that arise in practice, and how staff respond, can be turning points, good or bad, in youths' experience of the setting. They can also be opportunities for youth development. This article examines the wide‐ranging events, situations, or “dilemmas of practice” that occur in the daily life of youth development programs. Research shows that these varied situations are shaped by the ecology of diverse people and systems that influence the setting. They involve considerations that may entail everything from the psychology of different youth, to how parents from a cultural group think, to the dynamics of government systems. Expert youth practitioners, it is found, are able to identify more considerations than novices in these situations, and they possess a wider repertoire of responses. They also formulate more responses that are youth centered and address multiple considerations. Expertise involves being able to balance diverse concerns, including how to create and sustain conditions for the development of young people. Researchers can contribute by helping us better understand this array of situations and how experts respond. Improvement in the quality of youth settings can be achieved through greater knowledge of the tumble of events that occur and by helping train practitioners in skills for responding to it.
On the Crystal Chemistry of Oxometallates of Thorium
Authors: Müller‐Buschbaum Hanskarl
Published: April 2009

The crystal chemistry of the valence stable Thorium (Th4+) shows in oxovanadates, ‐niobates, ‐molybdates, ‐tantalates etc. typical cationic property. It depends on the big size of the Th4+ ion in the order of r(Th4+) = 0.92 Å (C.N. = 6) up to r(Th4+) = 1.34 Å (C.N. = 12), comparable with the radii of alkaline and alkaline earth metals: r(Na+) = 1.02 Å (C.N. = 6) or r(K+) = 1.5 Å (C.N. = 8); r(Ca2+/Sr2+) = 1.1 Å/1.26 Å (C.N. = 8). There exists only one typical compound that may be of the oxothorate type with the composition NaK3Th2O6. Na+ and K+ can be declared to be components of the cationic part of the crystal structure. In contrary, thorium and oxygen are common components of the anionic part of the crystal structure. From the point of view of the shared polyhedra (exclusively octahedra), NaK3Th2O6 belongs to the thorium‐oxometallates too. The report on oxometallates of thorium shows compounds with one, two, four and five Th4+ atoms in combination with V5+, Nb5+, Ta5+ and Mo6+. W6+ is completely missing. Some of the Tantalates belong to the Jahnberg compounds, showing planar nets of corner shared pentagonal bipyramids. ThMO4 and cationic mixed compounds, Th1–xAxMO4, crystallize with the Scheelite (respectively Huttonite) structure and at least Th4+ is part of ordered and disordered perowskites showing more or less deviations from the cubic symmetry.
Distance decay of community dynamics in rocky intertidal sessile assemblages evaluated by transition matrix models
Authors: Tsujino Masahiro , Hori Masakazu , Okuda Takehiro , Nakaoka Masahiro , Yamamoto Tomoko , Noda Takashi
Published: April 2009

It is well known that the similarity in species composition between two communities decays with the geographic distance that separates them. It is thus likely that the similarity in the dynamics of two communities also decays with distance, because the distance–decay relationship is fundamental in nature. However, the distance–decay relationships of community dynamics have not yet been revealed. We used transition matrix models to evaluate distance–decay relationships of seasonal community dynamics (from spring to summer) in rocky intertidal sessile assemblages along the Pacific coast of Japan between 31°N and 43°N. We evaluated the distance–decay relationships of whole‐community dynamics and of three dynamics‐related components—recruitment, disturbance, and species interaction (competition and facilitation)—for communities separated by distances ranging from several meters to thousands of kilometers. The similarity of the recruitment dynamics among communities declined rapidly with distance within the fine spatial scale, but only moderately within larger scales. The similarity of the disturbance dynamics was independent of distance, and the similarity of species interaction declined slightly with increasing distance. The similarity of whole‐community dynamics declined rapidly with distance at a fine spatial scale and moderately at larger scales. The fact that the distance–decay relationship of whole‐community dynamics was similar to that of recruitment may suggest that recruitment processes are the most important determinant of spatial variability of community dynamics at our study sites during the study period.
Tsunami modeling of a submarine landslide in the Fram Strait
Authors: Berndt Christian , Brune Sascha , Nisbet Euan , Zschau Jochen , Sobolev Stephan V.
Published: April 2009

The present geological setting west of Svalbard closely parallels the situation off mid‐Norway after the last glaciation, when crustal unloading by melting of ice induced very large earthquakes. Today, on the modern Svalbard margin, increasing bottom water temperatures are destabilizing marine gas hydrates, which are held in continental margin sediments consisting of interlayered contourite deposits and glacigenic debris flows. Both unloading earthquakes and hydrate failure have been identified as key factors causing several megalandslides off Norway during early Holocene deglaciation. The most prominent event was the Storegga Slide 8200 years B.P. which caused a tsunami up to 23 m high on the Faroe and Shetland islands. Here we show by numerical tsunami modeling that a smaller submarine landslide west of Svalbard, 100 m high and 130 km wide, would cause a tsunami capable of reaching northwest Europe and threatening coastal areas. A tsunami warning system based on tiltmeters would give a warning time of 1–4 h.
Quantification of uncertainty in pedotransfer function‐based parameter estimation for unsaturated flow modeling
Authors: Deng Hailin , Ye Ming , Schaap Marcel G. , Khaleel Raziuddin
Published: April 2009

While pedotransfer functions (PTFs) have long been applied to estimate soil hydraulic parameters for unsaturated flow and solute transport modeling, the uncertainty associated with the estimates is often ignored. The objective of this study is to evaluate uncertainty of the PTF‐estimated soil hydraulic parameters and its effect on numerical simulation of moisture flow. Contributing to the parameter estimation uncertainty are (1) the PTF intrinsic uncertainty caused by limited data used for PTF training and (2) the PTF input uncertainty in pedotransfer variables (i.e., PTF inputs). The PTF intrinsic uncertainty is assessed using the bootstrap method by generating multiple bootstrap realizations of the soil hydraulic parameters; the realizations follow normal or lognormal distributions. The PTF input variables (i.e., bulk density and soil texture) are obtained using the cokriging technique. The PTF input uncertainty is quantified by assuming that the cokriging estimates follow a normal distribution. Our results show that the PTF input uncertainty dominates over the PTF intrinsic uncertainty and determines the spatial distribution of the PTF parameter estimation uncertainty. When the parameter estimation uncertainty is included, the spatial variability of the measured soil hydraulic parameters is better captured. This is also the case for the observed moisture contents, whose spatial variability is well bracketed by the prediction intervals. However, this is only possible after the PTF input uncertainty is considered. These results suggest that additional sample acquisition for the PTF input variables would have a more favorable impact on reduction of the parameter estimation uncertainty than collecting additional soil hydraulic parameter measurements for PTF development.
Using Visual Analytics to Develop Situation Awareness in Astrophysics
Authors: Aragon Cecilia R. , Poon Sarah S. , Aldering Gregory S. , Thomas Rollin C. , Quimby Robert
Published: April 2009

We present a novel collaborative visual analytics application for cognitively overloaded users in the astrophysics domain. The system was developed for scientists who need to analyze heterogeneous, complex data under time pressure, and make predictions and time-critical decisions rapidly and correctly under a constant influx of changing data. The Sunfall Data Taking system utilizes several novel visualization and analysis techniques to enable a team of geographically distributed domain specialists to effectively and remotely maneuver a custom-built instrument under challenging operational conditions. Sunfall Data Taking has been in production use for 2 years by a major international astrophysics collaboration (the largest data volume supernova search currently in operation), and has substantially improved the operational efficiency of its users. We describe the system design process by an interdisciplinary team, the system architecture and the results of an informal usability evaluation of the production system by domain experts in the context of Endsley's three levels of situation awareness.
Nonvolatile static random access memory based on spin-transistor architecture
Authors: Shuto Yusuke , Yamamoto Shuu’ichirou , Sugahara Satoshi
Published: April 2009

The authors proposed and computationally analyzed nonvolatile static random access memory (NV-SRAM) architecture using a new type of spin transistor comprised of a metal-oxide-semiconductor field-effect transistor (MOSFET) and magnetic tunnel junction (MTJ) that is referred to as a pseudo-spin-MOSFET (PS-MOSFET). The PS-MOSFET is a circuit approach to reproduce the functions of spin transistors, based on recently progressed magnetoresistive random access memory technology. The proposed NV-SRAM cell can be simply configured by connecting two PS-MOSFETs to the storage nodes of a standard SRAM cell.
Theoretical prediction of atomic and electronic structure of neutral Si6Om (m=1–11) clusters
Authors: Caputo María C. , Oña Ofelia , Ferraro Marta B.
Published: April 2009

In this paper we found the most stable structures of silicon-oxide clusters of Si6Om (m=1–11) by using the genetic algorithm. In this work the genetic algorithm uses a semiempirical energy function, MSINDO, to find the best cluster structures of Si6Om (m=1–11). The best structures found were further optimized using the density functional theory. We report the stable geometries, binding energies, lowest unoccupied molecular orbital-highest occupied molecular orbital gap, dissociation energies for the most favorable fragmentation channels and polarizabilities of Si6Om (m=1–11). For most of the clusters studied here we report structures not previously found using limited search approaches on common structural motifs.
Nonadiabatic effects in the H+H2 exchange reaction: Accurate quantum dynamics calculations at a state-to-state level
Authors: Chu Tian-Shu , Han Ke-Li , Hankel Marlies , Balint-Kurti Gabriel G. , Kuppermann Aron , Abrol Ravinder
Published: April 2009

Real wave packet propagations were carried out on both a single ground electronic state and two-coupled-electronic states of the title reaction to investigate the extent of nonadiabatic effects on the distinguishable-atom reaction cross sections. The latest diabatic potential matrix of Abrol and Kuppermann [J. Chem. Phys. 116, 1035 (2002)] was employed in the present nonadiabatic quantum state-to-state scattering calculations over a total energy range-from threshold (the zero point of the reagent H2) to 3.0 eV. Based on the assumption that the hydrogen atoms are distinguishable in the collisions where the inelastic and elastic ones are excluded, no significant nonadiabatic effects have been found in the calculations of the full state-to-state integral and differential cross sections up to a total energy of 3.0 eV for product vibrational levels v′=0, 1, 2, 3. Our results therefore confirm the recent and the previous studies of the geometric phase effects in H+H2 employing a different diabatic double many-body expansion potential matrix or a different BKMP2 potential energy surface.
Enhanced photoluminescence of silicon oxide nanowires brought by prolonged thermal treatment during growth
Authors: Kim Jung H. , An Hyeun H. , Yoon Chong S.
Published: April 2009

Silicon oxide nanowires synthesized during carbonization of polyimide thin film on a silicon substrate exhibited marked enhancement in photoluminescence (PL) at 420 nm by prolonging the growth period. Maximum intensity was recorded when the nanowire diameter coarsened from 70 to 165 nm by extending the growth period from 1 to 3 h. The enhancement was attributed to the increase in concentration of neutral oxygen vacancies on the surface of the nanowires. It was also demonstrated that the PL peak can be shifted to 600 nm while maintaining the enhanced intensity by postannealing the nanowires in a reducing atmosphere.
Spherical magnetic nanoparticles: Magnetic structure and interparticle interaction
Authors: Russier V.
Published: April 2009

The interaction between spherical magnetic nanoparticles is investigated from micromagnetic simulations and analyzed in terms of the leading dipolar interaction energy between magnetic dipoles. We focus mainly on the case where the particles present a vortex structure. In the first step the local magnetic structure in the isolated particle is revisited. For particles bearing a uniaxial magnetocrystalline anisotropy, it is shown that the vortex core orientation relative to the easy axis depends on both the particle size and the anisotropy constant. When the particle magnetization presents a vortex structure, it is shown that the polarization of the particles by the dipolar field of the other one must be taken into account in the interaction. An analytic form is deduced for the interaction which involves the vortex core magnetization and the magnetic susceptibility which are obtained from the magnetic properties of the isolated particle.
Adiabatic Jacobi corrections on the vibrational energy levels of H2+ isotopologues
Authors: Fábri Csaba , Czakó Gábor , Tasi Gyula , Császár Attila G.
Published: April 2009

The effect of an adiabatic approximation, named adiabatic Jacobi correction (AJC) and introduced in J. Chem. Phys. 126, 024102 (2007), was investigated on the complete set of vibrational levels of H2+ and its isotopologues, most importantly on the highest-lying vibrational states of HD+. In order to perform clamped nuclei calculations employing finite nuclear masses a constrained Hamiltonian has been derived utilizing interparticle coordinates. The Born–Oppenheimer (BO) potential, the adiabatic potential obtained after taking into account the traditional diagonal Born–Oppenheimer correction (DBOC), as well as the AJC-corrected potential have been determined by an accurate fitting to computed energy values. These potentials were included in one-dimensional variational computations and yielded the complete set of energy levels for H2+, D2+, and HD+. A detailed investigation of the potential and the complete set of vibrational energy levels show the merits and the deficiencies of the BO, DBOC, and AJC treatments. In particular, it is shown that the AJC corrections are systematically smaller and have a different distance dependence than the DBOC corrections. For a large part of the spectrum of H2+ and its isotopologues the adiabatic correction to the vibrational energy levels is smaller than the nonadiabatic correction, the adiabatic DBOC correction has the highest overall accuracy for the prediction of vibrational energy levels, it is surpassed by the AJC correction only for the highest energy levels of HD+, and thus the use of the AJC correction is clearly the best choice only for states close to the dissociation limit of nonsymmetric isotopologues.
Classification of spatial surfaces with parallel mean curvature vector in pseudo-Euclidean spaces of arbitrary dimension
Authors: Chen Bang-Yen
Published: April 2009

Spatial surfaces with parallel mean curvature vector play some important roles in general relativity, theory of harmonic maps, as well as in differential geometry. Recently, spatial surfaces in four-dimensional Minkowski space time with parallel mean curvature vector were classified by Chen and Van der Veken [“Complete classification of parallel surfaces in 4-dimensional Lorentzian space forms,” Tohoku Math. J. 61, 1 (2009)]. In this article, we completely classify spatial surfaces with parallel mean curvature vector in pseudo-Euclidean spaces of arbitrary dimension. The main result states that there exist 16 families of such surfaces. As by-product, we achieve the complete classification of spatial surfaces with parallel mean curvature vector in Minkowski space times of arbitrary dimension.
Characterization and magnetic properties of Fe70Co30 alloy nanowire arrays
Authors: Yue G. H. , Wang L. S. , Wang X. , Chen Y. Z. , Peng D. L.
Published: April 2009

Highly ordered arrays of parallel Fe70Co30 nanowires with a diameter of about 50 nm and a length up to about several tens of micrometers were synthesized by two electrical fields in an anodized aluminum oxide film. The magnetic properties in the temperature range from 5 to 300 K were studied. When the applied field is along the long axis, the temperature dependence of coercivity of Fe70Co30 nanowire arrays shows a linear decrease with temperature increasing, which can be understood by a phenomenological nucleate model.
Effect of spatial nonlocality on terahertz optical interaction with quantum wells
Authors: Wang Guanghui , Guo Qi
Published: April 2009

Spatial nonlocal effects on optical absorption spectra from the terahertz optical interaction with semiconductor quantum wells (QWs) are investigated for two kinds of polarized states. The numerical results show that the spatial nonlocality of optical responses can lead to not only the blueshift but also the redshift of optical spectra, which depends on the QW depth. It is also demonstrated that the maximal radiation shift and the least optical absorbance can be obtained by adopting an appropriate step potential and polarization direction of incident terahertz wave. This work may provide some methods of designing the nanomaterials with large nonlocality and observing the spatial nonlocal effects by experiment.
Spectroscopic evidence for the specific Na+ and K+ interactions with the hydrogen-bonded water molecules at the electrolyte aqueous solution surfaces
Authors: Feng Ran-ran , Bian Hong-tao , Guo Yuan , Wang Hong-fei
Published: April 2009

Sum frequency generation vibrational spectra of the water molecules at the NaF and KF aqueous solution surfaces showed significantly different spectral features and different concentration dependence. This result is the first direct observation of the cation effects of the simple alkali cations, which have been believed to be depleted from the aqueous surface, on the hydrogen bonding structure of the water molecules at the electrolyte solution surfaces. These observations may provide important clues to understand the fundamental phenomenon of ions at the air/water interface.
Nonlinear resonant absorption of fast magnetoacoustic waves in strongly anisotropic and dispersive plasmas
Authors: Clack Christopher T. M. , Ballai Istvan
Published: April 2009

The nonlinear theory of driven magnetohydrodynamics (MHD) waves in strongly anisotropic and dispersive plasmas, developed for slow resonance by Clack and Ballai [Phys. Plasmas 15, 2310 (2008)] and Alfvén resonance by Clack et al. [Astron. Astrophys. 494, 317 (2009)], is used to study the weakly nonlinear interaction of fast magnetoacoustic (FMA) waves in a one-dimensional planar plasma. The magnetic configuration consists of an inhomogeneous magnetic slab sandwiched between two regions of semi-infinite homogeneous magnetic plasmas. Laterally driven FMA waves penetrate the inhomogeneous slab interacting with the localized slow or Alfvén dissipative layer and are partly reflected, dissipated, and transmitted by this region. The nonlinearity parameter defined by Clack and Ballai (2008) is assumed to be small and a regular perturbation method is used to obtain analytical solutions in the slow dissipative layer. The effect of dispersion in the slow dissipative layer is to further decrease the coefficient of energy absorption, compared to its standard weakly nonlinear counterpart, and the generation of higher harmonics in the outgoing wave in addition to the fundamental one. The absorption of external drivers at the Alfvén resonance is described within the linear MHD with great accuracy.
Dependence of protein mechanical unfolding pathways on pulling speeds
Authors: Li Mai Suan , Kouza Maksim
Published: April 2009

Mechanical unfolding of the fourth domain of Distyostelium discoideum filamin (DDFLN4) was studied in detail using the Cα-Go model. We show that unfolding pathways of this protein depend on the pulling speed. The agreement between theoretical and experimental results on the sequencing of unfolding events is achieved at low loading rates. The unfolding free energy landscape is also constructed using dependencies of unfolding forces on pulling speeds.
Electron scattering by trimethylene oxide, c-(CH2)3O, molecules
Authors: Szmytkowski Czesław , Domaracka Alicja , Możejko Paweł , Ptasińska-Denga Elżbieta
Published: April 2009

Electron-scattering cross sections have been determined for trimethylene oxide, cyclic (CH2)3O molecule, both experimentally and theoretically. The absolute total cross section (TCS) has been measured over energies from 1 to 400 eV using a linear electron-transmission method. The obtained TCS generally decreases with rising energy, except for the 3–10 eV range, where some resonantlike structures are discernible. Integral elastic cross section (ECS) and ionization cross section (ICS) have been also calculated up to 3 keV in the additivity rule approximation and the binary-encounter-Bethe approach, respectively. Their sum, ECS+ICS, is in a good agreement with the measured TCS. Comparison of the TCS energy dependence for trimethylene oxide with that for its isomeric open-chain counterpart—acetone, (CH3)2CO, has also been made. Moreover, examination of experimental TCSs for the cyclic (CH2)nO, n=2–4, ether series reveals that the intermediate-energy molecular TCSs for members of that family can be nicely represented as a sum of the effective TCSs for particular constituents of the molecule, i.e., methylene groups and oxygen atom. Finally, based on these partial TCSs, the TCS for the c-(CH2)5O—the next member of the series—has been determined and compared with the respective ECS+ICS values computed here for this compound.
Rotational quenching of CO2 by collision with He atoms
Authors: Yang Benhui , Stancil P. C.
Published: April 2009

Quantum mechanical scattering calculations are presented for the rotational relaxation of CO2 in collisions with He atoms with the close-coupling approach and the coupled-states approximation for collision energies between 10−6 and 10 000 cm−1. The He–CO2 interaction potential of Ran and Xie [J. Chem. Phys. 128, 124323 (2008)] was adopted and used to compute state-to-state cross sections for the quenching of the j=2, 4, 6, and 8 rotational levels of CO2. Numerous resonances, as a consequence of the van der Waals potential, are observed and the cross sections are found to approach the Wigner limit at low energies. Quenching rate coefficients are obtained for temperatures between 10−5 and 3000 K and applications to astrophysics and cold collisions are briefly discussed.
Vibrational relaxation in the Kubo oscillator: Stochastic pumping of heat
Authors: Segal Dvira
Published: April 2009

We present a model for a molecular level heat pump that operates when a stochastic time dependent force modulates the molecular vibrational energies. The model consists a molecular unit, represented by a Kubo oscillator, coupled to two solids characterized by distinct spectral properties and kept at unequal temperatures. In the fast modulation limit we derive expressions for the vibrational energy transition rates in the Kubo oscillator, and show that they do not trivially correspond to the population transition rates, unlike the field-free (or adiabatic) limit. We discuss the operation principle of the pump and manifest, analytically and numerically, directing of heat against a temperature gradient for a broad range of system and bath parameters. The present formalism could also describe a unidirectional exciton energy flow in a metal-molecule-metal junction under random noise.
Two-layer stratified flows over pronounced obstacles at low-to-intermediate Froude numbers
Authors: Cabeza Cecilia , Varela Juan , Bove Italo , Freire Daniel , Martí Arturo C. , Sarasúa L. G. , Usera Gabriel , Montagne Raul , Araujo Moacyr
Published: April 2009

Two-layer stratified flows over abrupt topographic obstacles, simulating relevant situations in oceanographic problems, are investigated numerically and experimentally in a simplified two-dimensional situation. Experimental results and numerical simulations are presented at low-to-intermediate Froude numbers for two different obstacles: one semicylindrical and the other prismatic. In both cases, four different flow regimes downstream of the obstacles are found: (I) subcritical flow, (II) internal hydraulic jump, (III) Kelvin–Helmholtz instability at the interface, and (IV) shedding of billows. The critical values of the Froude number for the transition between different regimes depend strongly on the shape of the obstacle. In regime (III), we show that the characteristics of the lee wave that appears past the obstacle can be explained with a theoretical stability analysis. Almost independence of the vortex shedding frequency with upstream velocity is observed and explained.
Four-component relativistic theory for NMR parameters: Unified formulation and numerical assessment of different approaches
Authors: Cheng Lan , Xiao Yunlong , Liu Wenjian
Published: April 2009

Several four-component relativistic approaches for nuclear magnetic shielding constant have recently been proposed and their formal relationships have also been established [Xiao et al., J. Chem. Phys. 126, 214101 (2007)]. It is shown here that the approaches can be recast into a unified form via the generic ansatz of orbital decomposition. The extension of the formalisms to magnetizability (and nuclear spin-spin coupling) is straightforward. Exact analytical expressions are also derived for both the shielding constant and magnetizability of the hydrogenlike atom in the ground state. A series of calculations on Rn85+ and Rn is then carried out to reveal the performance of the various methods with respect to the basis set requirement, leading to the conclusion that it is absolutely essential to explicitly account for the magnetic balance condition. However, different ways of doing so lead to quite similar results. It is also demonstrated that only extremely compact negative energy states are important for the total shieldings and their effects are hence essentially canceled out for chemical shifts. This has important implications for further theoretical developments.
Vertical coupling between short range surface plasmon polariton mode and dielectric waveguide mode
Authors: Wan Ruiyuan , Liu Fang , Tang Xuan , Huang Yidong , Peng Jiangde
Published: April 2009

Coupling performance between a short range surface plasmon polariton (SRSPP) mode and a conventional dielectric waveguide mode is demonstrated numerically. Simulation results show that the coupling length, as short as tens of microns, can be realized because the field of SRSPP extremely concentrates to the metal surface. SRSPP-based hybrid coupler provides not only an approach to realize highly compact functional devices, such as the TE-pass polarizer with high performance, but also an integratable route for efficiently exciting SRSPP mode, which is very useful in the SRSPP-based biosensor or SRSPP-assisted emission enhancement devices.
Ultralow noise microwave generation with fiber-based optical frequency comb and application to atomic fountain clock
Authors: Millo J. , Abgrall M. , Lours M. , English E. M. L. , Jiang H. , Guéna J. , Clairon A. , Tobar M. E. , Bize S. , Le Coq Y. , Santarelli G.
Published: April 2009

We demonstrate the use of a fiber-based femtosecond laser locked onto an ultrastable optical cavity to generate a low-noise microwave reference signal. Comparison with both a cryogenic sapphire oscillator (CSO) and a titanium-sapphire-based optical frequency comb system exhibit a stability of about 3×10−15 between 1 and 10 s. The microwave signal from the fiber system is used to perform Ramsey spectroscopy in a state-of-the-art cesium fountain clock. The resulting clock is compared to the CSO and exhibits a stability of 3.5×10−14τ−1/2.
Temperature dependence of Ohmic contact characteristics in AlGaN/GaN high electron mobility transistors from −50 to 200 °C
Authors: Liu Z. H. , Arulkumaran S. , Ng G. I.
Published: April 2009

The temperature dependent characteristics of Ti/Al/Ni/Au Ohmic contact for AlGaN/GaN high electron mobility transistors (HEMTs) on high-resistivity Si and sapphire substrates were investigated over the temperature range from −50 to 200 °C. The sheet resistances (Rsh) of AlGaN/GaN HEMTs on Si and sapphire substrates were found to increase with the temperature according to the power-law equation with power indices of −2.7 and −2.3, respectively. The specific contact resistivity (ρC) decreased with the temperature, and it was observed to be determined by the electron thermionic field emission (TFE) from the lowered conduction band edge in the modified AlGaN region with high-density N-vacancies to the quantum well at the AlGaN/GaN heterojunction with two dimensional electron gas (2DEG). Three important parameters in the TFE are extracted, that is, the barrier height (ϕB) of around 0.5 eV, the energy difference between the effective conductive-band edge and the Fermi level in 2DEG (En) of around 0.1 eV, and the 2DEG electron density (ND) with the order of magnitude of 1019 cm−3.
Explicitly correlated connected triple excitations in coupled-cluster theory
Authors: Köhn Andreas
Published: April 2009

A way to incorporate explicit electron correlation into connected triple excitations in coupled-cluster theory is proposed. The new ansatz is applied to the coupled-cluster singles and doubles model with noniterative triple excitations [CCSD(T)] and does not introduce any further sets of equations to be solved. A first implementation using automated generation and string-based evaluation of the explicit expressions is reported. The results demonstrate that the ansatz significantly enhances the basis set convergence of the noniterative triple excitation correction and thus improves upon previous approaches to explicitly correlated CCSD(T).
A stochastic spectral analysis of transcriptional regulatory cascades
Authors: Walczak Aleksandra M. , Mugler Andrew , Wiggins Chris H.
Published: April 2009

The past decade has seen great advances in our understanding of the role of noise in gene regulation and the physical limits to signaling in biological networks. Here, we introduce the spectral method for computation of the joint probability distribution over all species in a biological network. The spectral method exploits the natural eigenfunctions of the master equation of birth – death processes to solve for the joint distribution of modules within the network, which then inform each other and facilitate calculation of the entire joint distribution. We illustrate the method on a ubiquitous case in nature: linear regulatory cascades. The efficiency of the method makes possible numerical optimization of the input and regulatory parameters, revealing design properties of, e.g., the most informative cascades. We find, for threshold regulation, that a cascade of strong regulations converts a unimodal input to a bimodal output, that multimodal inputs are no more informative than bimodal inputs, and that a chain of up-regulations outperforms a chain of down-regulations. We anticipate that this numerical approach may be useful for modeling noise in a variety of small network topologies in biology.