bluuebunny/crossref_metadata_2025 huggingface dataset:
Internationale, englischsprachige Publikationen deutschsprachiger Arbeits- und Organisationspsychologen von 2000 bis 2005
Authors: Solga Marc , Schui Gabriel , Blickle Gerhard , Krampen Günter
Published: February 2008

Zusammenfassung. Dieser Beitrag untersucht die Forschungsthemen, die internationale Rezeption und einige methodische Aspekte von Publikationen deutschsprachiger Arbeits- und Organisationspsychologen, die in den Jahren 2000 bis 2005 in englischer Sprache in internationalen Zeitschriften und Jahresperiodika veröffentlicht wurden. Dabei werden einige inhaltliche Schwerpunkte deutlich, z. B. Belastung und Beanspruchung in der Arbeit/Stress, Eignungsdiagnostik/Personalauswahl, Führung, organisationales Commitment oder berufliche Selbstständigkeit/Unternehmertum. Die Zitationsanalysen zeigen, dass die englischsprachig publizierten Arbeiten deutschsprachiger Arbeits- und Organisationspsychologen international rezipiert und zitiert werden. Zitationsanalytische Indizes sind gleichwohl mit Vorsicht zu interpretieren; die zugrunde liegende Problematik wird ausführlich diskutiert.
Evolutionäres Denken: Missverständnisse, Trugschlüsse und Richtigstellungen
Authors: Schwab Frank
Published: February 2008

Zusammenfassung. Die psychologische Theorienbildung und Forschung des vergangenen Jahrhunderts war in erster Linie geprägt von Versuchen, die Psychologie zu ent-biologisieren. Aktuell werden jedoch neuere evolutionstheoretische Konzepte und Darwinsche Ideen auch auf die Untersuchung von Verhalten sowie auf mentale Strukturen und Prozesse übertragen. Nicht selten haben diese Erklärungen mit Missverständnissen und Trugschlüssen zu kämpfen. Die Evolutionspsychologie als eine der wichtigsten Schulen evolutionären Denkens bietet nützliche und viel versprechende wissenschaftliche Werkzeuge und Strategien, welche die Medienpsychologie mit den anderen ‘life sciences‘ verbindet. Sie blickt aus einer anderen Perspektive auf medienpsychologische Phänomene und bereichert derzeit noch vor allem theoretische Überlegungen innerhalb der Disziplin. Medienphänomene, die aus einer rein kognitiven Perspektive irrational erscheinen, können so erklärbar werden.
Zwischenwelten
Authors: Eibl Karl
Published: February 2008

Zusammenfassung. Der Aufsatz ermittelt die evolutionäre Grundausstattung, die es ermöglicht, dass wir der Welt durch Medien begegnen. Der Umgang mit relativ autonomen Zwischenwelten (fixiert in sprachlichen und ikonischen Zeichen), die Verwaltung der Informationen mittels des ‘Taggings‘ von Geltungsbereich und -grad (Bereichssyntax), die Entkoppelung und Neuverkoppelung von Informationen mit Auslösemechanismen sowie von Auslösemechanismen mit Verlaufsprogrammen, das ‘Switching‘ von Funktionsmodus und Organisationsmodus (Ernst und Spiel) und ein gesundes Misstrauen gegenüber Erzählungen ermöglichen auch den Umgang mit modernen, technischen Medien. Eine Überlastung dieser Grundausstattung und insbesondere der Fähigkeit zum ‘switching‘ droht allerdings seitens der Scheinauthentizität audiovisueller Medien und der Fülle von Real-Informationen ohne Handlungsrelevanz.
Zur Rezeption Angst auslösender Spielfilme
Authors: Weiß Kati , Krug Melanie , Suckfüll Monika
Published: February 2008

Zusammenfassung. Obwohl Menschen das Gefühl der Angst im Alltag unangenehm ist, wenden sich viele Zuschauer/innen fiktionalen Medieninhalten zu, die gerade diese Emotion hervorrufen möchten. Probehandeln als evolvierter psychologischer Mechanismus (EPM) kann in mehrerlei Hinsicht die Zuwendung zu Spielfilmen, die speziell auf Angst ausgerichtet sind, erklären. Eine Annahme beruht darauf, dass die Hemmung von energieaufwändigen Handlungen in uneindeutigen Situationen einen adaptiven Wert besitzt. Zudem verdeutlicht die Auseinandersetzung mit Angst auslösenden Filmen die Interrelation von phylogenetischen (stammesgeschichtlichen), ontogenetischen (lebensgeschichtlichen) und aktualgenetischen (situativen) Einflüssen.
Numerical simulations of volcanic jets: Importance of vent overpressure
Authors: Ogden Darcy E. , Wohletz Kenneth H. , Glatzmaier Gary A. , Brodsky Emily E.
Published: February 2008

Explosive volcanic eruption columns are generally subdivided into a gas‐thrust region and a convection‐dominated plume. Where vents have greater than atmospheric pressure, the gas‐thrust region is overpressured and develops a jet‐like structure of standing shock waves. Using a pseudogas approximation for a mixture of tephra and gas, we numerically simulate the effects of shock waves on the gas‐thrust region. These simulations are of free‐jet decompression of a steady state high‐pressure vent in the absence of gravity or a crater. Our results show that the strength and position of standing shock waves are strongly dependent on the vent pressure and vent radius. These factors control the gas‐thrust region's dimensions and the character of vertical heat flux into the convective plume. With increased overpressure, the gas‐thrust region becomes wider and develops an outer sheath in which the erupted mixture moves at higher speeds than it does near the column center. The radius of this sheath is linearly dependent on the vent radius and the square root of the overpressure. The sheath structure results in an annular vertical heat flux profile at the base of the convective plume, which is in stark contrast to the generally applied Gaussian or top‐hat profile. We show that the magnitude of expansion is larger than that predicted from previous 1D analyses, resulting in much slower average vertical velocities after expansion. These new relationships between vent pressure and plume expansion may be used with observations of plume diameter to constrain the pressure at the vent.
Impacts of 3‐D radiative effects on satellite cloud detection and their consequences on cloud fraction and aerosol optical depth retrievals
Authors: Yang Yuekui , Di Girolamo Larry
Published: February 2008

We present the first examination on how 3‐D radiative transfer impacts satellite cloud detection that uses a single visible channel threshold. The 3‐D radiative transfer through predefined heterogeneous cloud fields embedded in a range of horizontally homogeneous aerosol fields have been carried out to generate synthetic nadir‐viewing satellite images at a wavelength of 0.67 μm. The finest spatial resolution of the cloud field is 30 m. We show that 3‐D radiative effects cause significant histogram overlap between the radiance distribution of clear and cloudy pixels, the degree to which depends on many factors (resolution, solar zenith angle, surface reflectance, aerosol optical depth (AOD), cloud top variability, etc.). This overlap precludes the existence of a threshold that can correctly separate all clear pixels from cloudy pixels. The region of clear/cloud radiance overlap includes moderately large (up to 5 in our simulations) cloud optical depths. Purpose‐driven cloud masks, defined by different thresholds, are applied to the simulated images to examine their impact on retrieving cloud fraction and AOD. Large (up to 100s of %) systematic errors were observed that depended on the type of cloud mask and the factors that influence the clear/cloud radiance overlap, with a strong dependence on solar zenith angle. Different strategies in computing domain‐averaged AOD were performed showing that the domain‐averaged BRF from all clear pixels produced the smallest AOD biases with the weakest (but still large) dependence on solar zenith angle. The large dependence of the bias on solar zenith angle has serious implications for climate research that uses satellite cloud and aerosol products.
Evolution of host resistance in a toxin-producing bacterial–fungal alliance
Authors: Schmitt Imke , Partida-Martinez Laila P , Winkler Robert , Voigt Kerstin , Einax Esra , Dölz Franziska , Telle Sabine , Wöstemeyer Johannes , Hertweck Christian
Published: February 2008

The rice seedling blight fungus Rhizopus microsporus harbors endosymbiotic Burkholderia sp. for the production of the virulence factor, the antimitotic agent rhizoxin. Since the toxin highly efficiently blocks mitosis in most eukaryotes, it remained elusive how self-resistance emerged in the fungal host. In this study, rhizoxin sensitivity was systematically correlated with the nature of β-tubulin sequences in the kingdom Fungi. A total of 49 new β-tubulin sequences were generated for representative species of Ascomycota, Basidiomycota and Zygomycota. Rhizoxin sensitivity assays revealed two further amino acids at position 100 (Ser-100 and Ala-100), in addition to the known Ile-100 and Val-100, which convey rhizoxin resistance. All sensitive strains feature Asn-100. This hot spot was verified by modeling studies, which support the finding that rhizoxin preferentially interacts with the tubulin molecule in a cavity near position 100. Ancestral character state reconstructions conducted in a Bayesian framework suggest that rhizoxin sensitivity represents the ancestral character state in fungi, and that evolution of rhizoxin resistance took place in the ancestor of extant resistant Zygomycota. These findings support a model according to which endosymbiosis became possible through a parasitism—mutualism shift in insensitive fungi.
Response of fermentation and sulfate reduction to experimental temperature changes in temperate and Arctic marine sediments
Authors: Finke Niko , Jørgensen Bo Barker
Published: February 2008

Anaerobic degradation of organic material generally proceeds through a sequence of steps, including polymer hydrolysis, fermentation and respiration or methanogenesis. The intermediates, such as volatile fatty acids (VFA) or H2, are generally maintained at low concentration, showing a close coupling of the terminal oxidation to fermentation. We exposed marine sediments to extreme temperature perturbations to study the nature and robustness of this coupling. Bacterial sulfate reduction and its dependence on fermentation were studied experimentally over a broad temperature range of −0.3 to 40 °C in sediments from temperate and permanently cold environments. In an Arctic sediment from Svalbard, the apparent optimum temperature for sulfate reduction decreased with prolonged incubation, whereas sulfate reduction rates increased. In a temperate sediment from the North Sea, the apparent optimum temperature was higher and did not change with incubation time. Up to a critical temperature, the concentrations of VFA remained low, <3 μm for acetate and <1 μm for the other VFA, the H2 concentration showed thermodynamic control by sulfate-reducing bacteria, revealing a close coupling of fermentation and sulfate reduction. Above the critical temperature, the concentrations of VFA and H2 increased transiently by 100–1000-fold. According to the different in situ temperatures of the samples, the critical temperature was lower for sediments from the Arctic than from the North Sea. The H2 concentrations decreased again upon prolonged incubation to values typical for sulfate-depleted methanogenic sediments. This suggests that fermentative bacteria and methanogenic archaea in both sediments tolerated higher temperatures than the sulfate-reducing community.
Health Perceptions and Demographic Characteristics Associated With Underassessment of Body Weight
Authors: Gregory Cria O. , Blanck Heidi M. , Gillespie Cathleen , Maynard L. Michele , Serdula Mary K.
Published: February 2008

Objectives: To describe the relationship between BMI and perceived weight status and to determine how underassessment of weight status is associated with demographic characteristics, self‐reported general health, and perceived health risk in relation to one's body weight.

Methods and Procedures: In the 2004 Styles surveys, 3,888 US adult participants described their current weight status (underweight, about right, slightly overweight, very overweight), which we compared with self‐reported BMI in order to determine concordance. We used multivariable logistic regression to evaluate associations between underassessment of body weight and characteristics of interest.

Results: Among persons with a BMI ≥25, women were more likely than men to recognize their overweight status (slightly or very overweight; 93.0% of women vs. 73.5% of men) and the extent to which they were overweight: 70.4% of obese women vs. 49.5% of obese men described themselves as very overweight. Among the overweight and obese of both sexes, disagreement with regard to current weight as a health risk was associated with underassessment of weight. Additional factors associated with underassessment were education and race/ethnicity among overweight women; race/ethnicity among overweight men; household income and self‐rated health among obese women; and self‐rated health among obese men (P < 0.05).

Discussion: While most of the obese participants recognized that they were overweight, many of them, particularly among the men, did not realize the extent to which they were overweight. Public health messages may be more effective if they are specifically tailored to target audiences, besides emphasizing the health risks associated with excess body weight.
Impaired Skeletal Muscle Substrate Oxidation in Glucose‐intolerant Men Improves After Weight Loss
Authors: Corpeleijn Eva , Mensink Marco , Kooi Marianne E. , Roekaerts Paul M.H.J. , Saris Wim H.M. , Blaak Ellen E.
Published: February 2008

Objective: An impaired fatty acid handling in skeletal muscle may be involved in the development of insulin resistance and diabetes mellitus type 2 (DM2). We investigated muscle fatty acid metabolism in glucose‐intolerant men (impaired glucose tolerance (IGT)), a prediabetic state, relative to BMI‐matched control men (normal glucose tolerance (NGT)) during fasting and after a meal, because most people in the western society are in the fed state most of the day.

Methods and Procedures: Skeletal muscle free fatty acid (FFA) uptake and oxidation were studied using the stable isotope tracer [2,2‐2H]‐palmitate and muscle indirect calorimetry in the forearm model during fasting and after a mixed meal (33 energy % (E%) carbohydrates, 61 E% fat). Intramyocellular triglycerides (IMTGs) were monitored with 1H‐magnetic resonance spectroscopy. IGT men were re‐examined after weight loss (−15% of body weight (BW)).

Results: The postprandial increase in forearm muscle respiratory quotient (RQ) was blunted in IGT compared to NGT, but improved after weight loss. Weight loss also improved fasting‐fat oxidation and tended to decrease IMTGs (P = 0.08). No differences were found in fasting and postprandial forearm muscle fatty acid uptake between NGT and IGT, or in IGT before and after weight loss.

Discussion: The ability to switch from fat oxidation to carbohydrate oxidation after a meal is already impaired in the prediabetic state, suggesting this may be an early factor in the development toward DM2. This impaired ability to regulate fat oxidation during fasting and after a meal (impaired metabolic flexibility) can be (partly) reversed by weight loss.
DataMeadow: A Visual Canvas for Analysis of Large-Scale Multivariate Data
Authors: Elmqvist Niklas , Stasko John , Tsigas Philippas
Published: February 2008

Supporting visual analytics of multiple large-scale multidimensional data sets requires a high degree of interactivity and user control beyond the conventional challenges of visualizing such data sets. We present the DataMeadow, a visual canvas providing rich interaction for constructing visual queries using graphical set representations called DataRoses. A DataRose is essentially a starplot of selected columns in a data set displayed as multivariate visualizations with dynamic query sliders integrated into each axis. The purpose of the DataMeadow is to allow users to create advanced visual queries by iteratively selecting and filtering into the multidimensional data. Furthermore, the canvas provides a clear history of the analysis that can be annotated to facilitate dissemination of analytical results to stakeholders. A powerful direct manipulation interface allows for selection, filtering, and creation of sets, subsets, and data dependencies. We have evaluated our system using a qualitative expert review involving two visualization researchers. Results from this review are favorable for the new method.
Visual Analysis of Controversy in User-Generated Encyclopedias
Authors: Brandes Ulrik , Lerner Jürgen
Published: February 2008

Wikipedia is a large and rapidly growing Web-based collaborative authoring environment, where anyone on the Internet can create, modify, and delete pages about encyclopedic topics. A remarkable property of some Wikipedia pages is that they are written by up to thousands of authors who may have contradicting opinions. In this paper, we show that a visual analysis of the ‘who revises whom’-network gives deep insight into controversies. We propose a set of analysis and visualization techniques that reveal the dominant authors of a page, the roles they play, and the alters they confront. Thereby we provide tools to understand how Wikipedia authors collaborate in the presence of controversy.
Visual Analytics Approach to User-Controlled Evacuation Scheduling
Authors: Andrienko Gennady , Andrienko Natalia , Bartling Ulrich
Published: February 2008

Application of the ideas of visual analytics is a promising approach to supporting decision making, in particular, where the problems have geographic (or spatial) and temporal aspects. Visual analytics may be especially helpful in time-critical applications, which pose hard challenges to decision support. We have designed a suite of tools to support transportation-planning tasks such as emergency evacuation of people from a disaster-affected area. The suite combines a tool for automated scheduling based on a genetic algorithm with visual analytics techniques allowing the user to evaluate tool results and direct its work. A transportation schedule, which is generated by the tool, is a complex construct involving geographical space, time, and heterogeneous objects (people and vehicles) with states and positions varying in time. We apply task-analytical approach to design techniques that could effectively support a human planner in the analysis of this complex information.
Computational investigation of the Jahn-Teller effect in the ground and excited electronic states of the tropyl radical. Part I. Theoretical calculation of spectroscopically observable parameters
Authors: Stakhursky Vadim L. , Sioutis Ilias , Tarczay György , Miller Terry A.
Published: February 2008

Theoretical calculations are performed for the X̃E2″2 and ÃE3″2 states of the cycloheptatrienyl (tropyl) radical C7H7. An important goal of these calculations is to predict and to guide the analysis of the experimentally observed ÃE3″2-X̃E2″2 electronic spectrum. Vibrational frequencies of the tropyl radical at the conical intersection and stationary points of its X̃ and Ã state Jahn-Teller distorted potential energy surfaces are given. Spectroscopically obtainable parameters describing the Jahn-Teller effect are calculated for the X̃ and Ã electronic states. Additionally, the stabilization energies for the X̃ and Ã states are computed at the CASSCF(7,7) and EOMEA-CCSD levels of theory using various basis sets.
Growth behavior of La@Sin (n=1–21) metal-encapsulated clusters
Authors: Peng Qi , Shen Jiang
Published: February 2008

Density functional theory involving generalized gradient approximation correlation functional is used to investigate the cluster series La@Sin (n=1–21). We find that the growth process of La@Sin (n=1–21) could be divided into three stages: First, La atom adheres to other Si atoms in the size range of 1⩽n⩽10; then, La atom is surrounded by Si atoms with basketlike structures in the size range of 11⩽n⩽15; finally, La atom is completely encapsulated into the fullerene cage structures in the size range of 16⩽n⩽21. The growth of fullerene cage starts from La@Si16 and stops at La@Si20. By studying La@Sin+ cations and La@Sin− anions, we find that the La atom charge curves of neutral clusters, cations, and anions have a cross point at La@Si12. Adiabatic ionization potential and electron affinity are studied too. Lastly, based on the ground state geometries of La@Sin clusters, we simulate the chemical reaction in which La@SinH2n+ cation has been produced and explain why Hiura et al. [Phys. Rev. Lett. 86, 1733 (2001)] only observed La@SinH2n+ (n=1–4) cations in their experiment.
Interfacial reactions of Pt-based Schottky contacts on InGaP
Authors: Chu L. H. , Chang E. Y. , Wu Y. H. , Huang J. C. , Chen Q. Y. , Chu W. K. , Seo H. W. , Lee C. T.
Published: February 2008

We have investigated the interfacial reaction between platinum and InGaP in a Schottky diode structure. There was a 7.5-nm-thick amorphous layer formed at the interface between Pt and InGaP after metal deposition. After annealing at 325°C for 1min, this amorphous layer increased to 12.8nm and the reverse leakage current also decreased. The diffusion of Pt atoms and the crystallization of amorphous layer took place after annealing at 325°C for 10min. Prolonging the annealing to 3h led to formation of Ga2Pt and GaPt3 phases in InGaP and Schottky diodes degraded after these new phases were observed.
Reaction dynamics of Si(PJ3)+O2→SiO(XΣ+1)+O studied by a crossed-beam laser-induced fluorescence technique
Authors: Yamashiro R. , Matsumoto Y. , Honma K.
Published: February 2008

Oxidation reaction of the ground state Si atom was studied by using a crossed molecular beam technique at 13.0kJ∕mol of collision energy. The Si atomic beam was generated by laser vaporization and crossed with the oxygen molecular beam at right angle. Products at the crossing region were detected by the laser-induced fluorescence (LIF). The LIF of SiO(AΠ1-XΣ+1) was used to determine the vibrational state distribution of the electronic ground state, SiO(XΣ+1). The determined distribution was inverted with the maximum population at v″=4, and in good agreement with the recent quasiclassical trajectory calculation on the singlet potential energy surface. The agreement suggested that an abstraction mechanism is dominant at the collision energy studied here. One of the counterproducts, O(PJ3), was also observed by the vacuum ultraviolet LIF and the distribution of the spin-orbit levels were determined. The formation of O(PJ3) was consistent with the significant population of v″=7 and 8 states of SiO, which could be explained by the presence of the triplet product channel with higher exothermicity.
Performance of a nonempirical meta–generalized gradient approximation density functional for excitation energies
Authors: Tao Jianmin , Tretiak Sergei , Zhu Jian-Xin
Published: February 2008

It is known that the adiabatic approximation in time-dependent density functional theory usually provides a good description of low-lying excitations of molecules. In the present work, the capability of the adiabatic nonempirical meta–generalized gradient approximation (meta-GGA) of Tao, Perdew, Staroverov, and Scuseria (TPSS) to describe atomic and molecular excitations is tested. The adiabatic (one-parameter) hybrid version of the TPSS meta-GGA and the adiabatic GGA of Perdew, Burke, and Ernzerhof (PBE) are also included in the test. The results are compared to experiments and to those obtained with two well-established hybrid functionals PBE0 and B3LYP. Calculations show that both adiabatic TPSS and TPSSh functionals produce excitation energies in fairly good agreement with experiments, and improve upon the adiabatic local spin density approximation and, in particular, the adiabatic PBE GGA. This further confirms that TPSS is indeed a reliable nonhybrid universal functional which can serve as the starting point from which higher-level approximations can be constructed. The systematic underestimate of the low-lying vertical excitation energies of molecules with time-dependent density functionals within the adiabatic approximation suggests that further improvement can be made with nonadiabatic corrections.
Adsorption and dissociation of hydrogen molecules on a Pt atom on defective carbon nanotubes
Authors: Park Yongjin , Kim Gunn , Lee Young Hee
Published: February 2008

Using density functional calculations, we investigate the catalytic effect of a Pt atom on a defective carbon nanotube. The Pt atom binds more strongly to the vacancy site than to the Stone-Wales defect and to the pure surface of the nanotube. The binding energy of the H2 molecule on the vacancy is significantly reduced to 0.68eV from 1.26eV of the pure (5,5) nanotube but still sufficient enough to maintain minimum bond strength on the Pt atom. Moreover, the H–H distance is separated to 2.16Å. The feasibility to the fuel cell is further discussed.
Ferroelectric and ferromagnetic properties of Gd substituted nickel ferrite
Authors: Kamala Bharathi K. , Markandeyulu G.
Published: February 2008

Ferromagnetic and ferroelectric characteristics of Gd substituted nickel ferrite (NiO⋅Fe1.925Gd0.075O3) were investigated. The material formed in the cubic inverse spinel phase and in addition, a small amount of GdFeO3 phase was identified. A small distortion of the cubic lattice was observed upon the substitution of Fe by Gd in the B site. Substitution of Gd for Fe lowered the saturation magnetization. However, the saturation magnetostriction is seen not to change significantly by the substitution of Gd. From the temperature variation of dielectric constant measurement, the ferroelectric transition temperature was found to be 512K. The existence of the ferroelectricity was confirmed from the ferroelectric loop. The (high) dielectric constant with frequency is seen to reveal a dispersion of relaxation times.
Structural and magnetic properties of ball-milled Ni11Co11Fe66Zr7B4Cu powders
Authors: Baraskar Ashish K. , Chen Yajie , Yoon Soack Dae , Chinnasamy C. N. , Sun Nian , Vittoria Carmine , Harris Vincent G. , Heil Todd , Willard Matthew
Published: February 2008

Thick films of the Ni11Co11Fe66Zr7B4Cu composition were synthesized via screen printing of the ball-milled ribbons of the above composition for possible use as planar inductors. The ribbons were obtained by rapid solidification. The resulting ribbon samples were annealed at 300°C for 2h to cause embrittlement. They were found to have soft magnetic properties (4πMs∼13kG, ΔH∼100Oe, and Hc<0.5Oe). The brittle ribbons were ball milled using tungsten carbide vials and stainless steel balls in an inert atmosphere for various milling times. The sample milled for 10h was found to have a 4πMs of about 13kG and a coercivity of about 73Oe with an average particle size of about 5μm. The screen printed (as prepared and aligned) samples showed a linewidth (ΔH) of about 1000Oe. Similar values were obtained for screen printed films annealed for 1h at 200 and 400°C.
Structural, magnetic, and mechanical properties of 5μm thick SmCo films suitable for use in microelectromechanical systems
Authors: Walther A. , Givord D. , Dempsey N. M. , Khlopkov K. , Gutfleisch O.
Published: February 2008

5 μ m thick SmCo films were deposited onto Si substrates using triode sputtering. A study of the influence of deposition temperature (Tdep⩽600°C) on the structural, magnetic, and mechanical properties has shown that optimum properties [highest degree of in-plane texture, maximum in-plane coercivity and remanence (1.3 and 0.8T, respectively), and no film peel-off] are achieved for films deposited at the relatively low temperature of 350°C. This temperature is compatible with film integration into microelectromechanical systems. The deposition rate was increased from 3.6to18μm∕h by increasing the surface area of the target from 7to81cm2 while keeping the target potential fixed. Mechanically intact films could be prepared by deposition onto prepatterned films or deposition through a mask.
An alternative analysis of some recent diffusion experiments on the large plasma device
Authors: Simon Albert
Published: February 2008

The results of a recent numerical analysis of a diffusion experiment on the large plasma device (LAPD) [Maggs et al., Phys. Plasmas 14, 052507 (2007)] are re-examined. A simplified analytic solution of the transport equations is obtained by including previously omitted contributions to the transport. This solution strongly suggests that an accurate determination of the perpendicular diffusion coefficient would be very difficult in the specific LAPD experimental arrangement, due to near-cancellation of large terms. Thus, caution should be exercised in claiming that Bohm diffusion, or its suppression in the presence of a large applied radial voltage, has been observed.
Stabilization of the magnetosonic instability and destabilization of nonlinear electrostatic waves due to finite amplitude Alfvén waves in a two ion-beam plasma
Authors: Gomberoff L.
Published: February 2008

It has been shown that a large amplitude Alfvén wave can stabilize linear magnetosonic instabilities triggered by an ion beam. This phenomenon occurs for large amplitude waves above a threshold value. Here the effect of a second ion beam on the threshold amplitude for stabilization of the magnetosonic instability is studied. It is shown that the second beam modifies the threshold amplitude behavior for complete saturation of the magnetosonic instability. The effect of the second beam on the properties of purely electrostatic nonlinear instabilities triggered by the finite amplitude wave is also studied. Apart from the changes induced by the second beam on the threshold amplitude behavior, it is shown that in some cases there are two regimes of the nonlinear ion-acousticlike instability. These results should be of importance in those environments where the interplay of the two beams should not be ignored like, e.g., in the fast solar wind.
Current-driven magnetization reversal at extremely low threshold current density in (Ga,Mn)As-based double-barrier magnetic tunnel junctions
Authors: Watanabe Maya , Okabayashi Jun , Toyao Hiroshi , Yamaguchi Takeshi , Yoshino Junji
Published: February 2008

Current-driven magnetic orientation reversal at an extremely low threshold current density, as low as 2.0×104A∕cm2, has been achieved in (Ga,Mn)As-based double-barrier magnetic tunneling junctions (MTJs) sandwiched between top and bottom MTJs. The middle magnetic free layer thickness dependence clearly demonstrates that the low threshold current density is owing not only to the small magnetization of the magnetic free layer but also the enhancement of the spin torque caused by a spin-polarized current through the top and bottom MTJs.
Development of compact high precision two degree of freedom XY piezoelectric stepping positioner
Authors: Kang Dongwoo , Kim Jungjae , Lee Moon G. , Gweon Daegab
Published: February 2008

In this article, a linear piezoelectric stepping positioner developed by Kang et al. [Rev. Sci. Instrum. 78, 075112 (2007)] is extended to have a two degree of freedom XY linear motion and it is experimentally evaluated. A resolution less than 10nm, a speed of over 0.5mm∕s, push forces of 17.9 and 19.5, and stiffnesses of 6.54 and 5.90N∕μm are attained while maintaining a compact size of 96×96×39mm3 and the required power consumption of 102.74W.
Collisionless forced magnetic reconnection in an electron-positron plasma
Authors: Hosseinpour M. , Vekstein G.
Published: February 2008

Collisionless forced magnetic reconnection in an electron-positron plasma, where the mechanism of the magnetic field breaking is inertia of plasma particles, is considered. The model under analytical investigation is the so-called Taylor problem: a tearing stable slab plasma equilibrium with a magnetic field reversal is subjected to a small-amplitude boundary perturbation that drives magnetic reconnection at the neutral surface within the plasma. It is shown that forced collisionless reconnection has a direct analogy with its collisional (resistive) counterpart investigated by T. S. Hahm and R. M. Kulsrud [Phys. Fluids 28, 2412 (1985)], with the role of the inverse Lundquist number S−1≪1 of the resistive magnetohydrodynamics now being played by the normalized inertia skin depth d≡cωpa≪1 (ωp is the electron-positron plasma frequency, and a is a width of the plasma slab). The transition between the collisionless and resistive regimes of forced reconnection is also considered.
Substrate-induced strain effect in La0.875Ba0.125MnO3 thin films grown on ferroelectric single-crystal substrates
Authors: Zheng R. K. , Wang Y. , Chan H. L. W. , Choy C. L. , Luo H. S.
Published: February 2008

The authors have studied the substrate-induced strain effect in La0.875Ba0.125MnO3 (LBMO) thin films grown on ferroelectric 0.67Pb(Mg1∕3Nb2∕3)O3–0.33PbTiO3 (PMN-PT) single-crystal substrates. Both the strain and resistance of the films can be in situ varied by applying an electric field across the PMN-PT substrates. X-ray diffraction analysis indicates that the variations of strain and resistance result from the induced strain in the PMN-PT substrate due to the ferroelectric polarization or the converse piezoelectric effect. The relationships between the resistance and the induced strain in the LBMO film and PMN-PT substrate have been quantitatively analyzed.
Intrinsic luminance loss in phosphorescent small-molecule organic light emitting devices due to bimolecular annihilation reactions
Authors: Giebink N. C. , D’Andrade B. W. , Weaver M. S. , Mackenzie P. B. , Brown J. J. , Thompson M. E. , Forrest S. R.
Published: February 2008

Operational degradation of blue electrophosphorescent organic light emitting devices (OLEDs) is studied by examining the luminance loss, voltage rise, and emissive layer photoluminescence quenching that occur in electrically aged devices. Using a model where defect sites act as deep charge traps, nonradiative recombination centers, and luminescence quenchers, we show that the luminance loss and voltage rise dependence on time and current density are consistent with defect formation due primarily to exciton-polaron annihilation reactions. Defect densities ∼1018cm−3 result in >50% luminance loss. Implications for the design of electrophosphorescent OLEDs with improved lifetime are discussed.
Strontium and barium iodide high light yield scintillators
Authors: Cherepy Nerine J. , Hull Giulia , Drobshoff Alexander D. , Payne Stephen A. , van Loef Edgar , Wilson Cody M. , Shah Kanai S. , Roy Utpal N. , Burger Arnold , Boatner Lynn A. , Choong Woon-Seng , Moses William W.
Published: February 2008

Europium-doped strontium and barium iodide are found to be readily growable by the Bridgman method and to produce high scintillation light yields. SrI2(Eu) emits into the Eu2+ band, centered at 435nm, with a decay time of 1.2μs and a light yield of ∼90000photons∕MeV. It offers energy resolution better than 4% full width at half maximum at 662keV, and exhibits excellent light yield proportionality. BaI2(Eu) produces >30000photons∕MeV into the Eu2+ band at 420nm (<1μs decay). An additional broad impurity-mediated recombination band is present at 550nm (>3μs decay), unless high-purity feedstock is used.
Acceleration gradient of a plasma wakefield accelerator
Authors: Uhm Han S.
Published: February 2008

The phase velocity of the wakefield waves is identical to the electron beam velocity. A theoretical analysis indicates that the acceleration gradient of the wakefield accelerator normalized by the wave breaking amplitude is K0(ξ)∕K1(ξ), where K0(ξ) and K1(ξ) are the modified Bessel functions of the second kind of order zero and one, respectively and ξ is the beam parameter representing the beam intensity. It is also shown that the beam density must be considerably higher than the diffuse plasma density for the large radial velocity of plasma electrons that are required for a high acceleration gradient.
A concept of ferroelectric microparticle propulsion thruster
Authors: Yarmolich D. , Vekselman V. , Krasik Ya. E.
Published: February 2008

A space propulsion concept using charged ferroelectric microparticles as a propellant is suggested. The measured ferroelectric plasma source thrust, produced mainly by microparticles emission, reaches ∼9×10−4N. The obtained trajectories of microparticles demonstrate that the majority of the microparticles are positively charged, which permits further improvement of the thruster.
Cosmogenic nuclide dating of
Sahelanthropus tchadensis
and
Australopithecus bahrelghazali
: Mio-Pliocene hominids from Chad
Authors: Lebatard Anne-Elisabeth , Bourlès Didier L. , Duringer Philippe , Jolivet Marc , Braucher Régis , Carcaillet Julien , Schuster Mathieu , Arnaud Nicolas , Monié Patrick , Lihoreau Fabrice , Likius Andossa , Mackaye Hassan Taisso , Vignaud Patrick , Brunet Michel
Published: February 2008

Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern Chad). In the Koro Toro fossiliferous area, KT 12 locality (16°00′N, 18°53′E) was the site of discovery of
Australopithecus bahrelghazali
(Abel) and in the Toros-Menalla fossiliferous area, TM 266 locality (16°15′N, 17°29′E) was the site of discovery of
Sahelanthropus tchadensis
(Toumaï). At both localities, the evolutive degree of the associated fossil mammal assemblages allowed a biochronological estimation of the hominid remains: early Pliocene (3–3.5 Ma) at KT 12 and late Miocene (≈7 Ma) at TM 266. Atmospheric
10
Be, a cosmogenic nuclide, was used to quasicontinuously date these sedimentary units. The authigenic
10
Be/
9
Be dating of a pelite relic within the sedimentary level containing Abel yields an age of 3.58 ± 0.27 Ma that points to the contemporaneity of
Australopithecus bahrelghazali
(Abel) with
Australopithecus afarensis
(Lucy). The 28
10
Be/
9
Be ages obtained within the anthracotheriid unit containing Toumaï bracket, by absolute dating, the age of
Sahelanthropus tchadensis
to lie between 6.8 and 7.2 Ma. This chronological constraint is an important cornerstone both for establishing the earliest stages of hominid evolution and for new calibrations of the molecular clock.
Yeast Pch2 promotes domainal axis organization, timely recombination progression, and arrest of defective recombinosomes during meiosis
Authors: Börner G. Valentin , Barot Aekam , Kleckner Nancy
Published: February 2008

We show that, during budding yeast meiosis, axis ensemble Hop1/Red1 and synaptonemal complex (SC) component Zip1 tend to occur in alternating strongly staining domains. The widely conserved AAA+-ATPase Pch2 mediates this pattern, likely by means of direct intervention along axes. Pch2 also coordinately promotes timely progression of cross-over (CO) and noncross-over (NCO) recombination. Oppositely, in a checkpoint-triggering aberrant situation (
zip1
Δ), Pch2 mediates robust arrest of stalled recombination complexes, likely via nucleolar localization. We suggest that, during WT meiosis, Pch2 promotes progression of SC-associated CO and NCO recombination complexes at a regulated early–midpachytene transition that is rate-limiting for later events; in contrast, during defective meiosis, Pch2 ensures that aberrant recombination complexes fail to progress so that intermediates can be harmlessly repaired during eventual return to growth. Positive vs. negative roles of Pch2 in the two situations are analogous to positive vs. negative roles of Mec1/ATR, suggesting that Pch2 might mediate Mec1/ATR activity. We further propose that regulatory surveillance of normal and abnormal interchromosomal interactions in mitotic and meiotic cells may involve “structure-dependent interchromosomal interaction” (SDIX) checkpoints.
Defining genetic interaction
Authors: Mani Ramamurthy , St.Onge Robert P. , Hartman John L. , Giaever Guri , Roth Frederick P.
Published: February 2008

Sometimes mutations in two genes produce a phenotype that is surprising in light of each mutation's individual effects. This phenomenon, which defines genetic interaction, can reveal functional relationships between genes and pathways. For example, double mutants with surprisingly slow growth define synergistic interactions that can identify compensatory pathways or protein complexes. Recent studies have used four mathematically distinct definitions of genetic interaction (here termed Product, Additive, Log, and Min). Whether this choice holds practical consequences has not been clear, because the definitions yield identical results under some conditions. Here, we show that the choice among alternative definitions can have profound consequences. Although 52% of known synergistic genetic interactions in
Saccharomyces cerevisiae
were inferred according to the Min definition, we find that both Product and Log definitions (shown here to be practically equivalent) are better than Min for identifying functional relationships. Additionally, we show that the Additive and Log definitions, each commonly used in population genetics, lead to differing conclusions related to the selective advantages of sexual reproduction.
Highly efficient and large-scale generation of functional dopamine neurons from human embryonic stem cells
Authors: Cho Myung Soo , Lee Young-Eun , Kim Ji Young , Chung Seungsoo , Cho Yoon Hee , Kim Dae-Sung , Kang Sang-Moon , Lee Haksup , Kim Myung-Hwa , Kim Jeong-Hoon , Leem Joong Woo , Oh Sun Kyung , Choi Young Min , Hwang Dong-Youn , Chang Jin Woo , Kim Dong-Wook
Published: February 2008

We developed a method for the efficient generation of functional dopaminergic (DA) neurons from human embryonic stem cells (hESCs) on a large scale. The most unique feature of this method is the generation of homogeneous spherical neural masses (SNMs) from the hESC-derived neural precursors. These SNMs provide several advantages: (
i
) they can be passaged for a long time without losing their differentiation capability into DA neurons; (
ii
) they can be coaxed into DA neurons at much higher efficiency than that from previous reports (86% tyrosine hydroxylase-positive neurons/total neurons); (
iii
) the induction of DA neurons from SNMs only takes 14 days; and (
iv
) no feeder cells are required during differentiation. These advantages allowed us to obtain a large number of DA neurons within a short time period and minimized potential contamination of unwanted cells or pathogens coming from the feeder layer. The highly efficient differentiation may not only enhance the efficacy of the cell therapy but also reduce the potential tumor formation from the undifferentiated residual hESCs. In line with this effect, we have never observed any tumor formation from the transplanted animals used in our study. When grafted into a parkinsonian rat model, the hESC-derived DA neurons elicited clear behavioral recovery in three behavioral tests. In summary, our study paves the way for the large-scale generation of purer and functional DA neurons for future clinical applications.
Placental histological inflammation and reproductive tract infections in a low risk pregnant population in Latvia
Authors: REZEBERGA DACE , LAZDANE GUNTA , KROICA JUTA , SOKOLOVA LUDMILA , DONDERS GILBERT G.G.
Published: February 2008

Background. To investigate the correlation of reproductive tract infections (RTI) and endogenous vaginal flora at first antenatal consultation with placental histological inflammation. Methods. In a follow‐up study, 154 low risk women with no miscarriage risk factors were examined for the presence of Neisseria gonorrhoeae, Trichomonas vaginalis, Chlamydia trachomatis, Ureaplasma urealyticum, Mycoplasma hominis, Gardnerella vaginalis, Streptococcus agalactiae (GBS), Staphylococcus aureus, Enterococcus faecalis (GDS) and bacterial vaginosis (BV). At delivery, outcome data were collected and the histology of the placenta was studied. Results. Some 85 (56.3%) of all pregnant women had RTI or endogenous vaginal flora. Placental histological inflammation correlated with genital tract colonisation with G. vaginalis (p =0.013), BV (p =0.031), S. aureus (p =0.04) and aerobic vaginitis (p =0.017). BV and BV‐related G. vaginalis correlated with the presence of parietal and placental chorioamnionitis in 53.8 and 43.5% of cases. Genital tract colonisation with GDS and other aerobic flora in combination with inflammatory vaginitis correlated with the presence of funisitis in 33.3 and 40.0% of cases. Mycoplasmas increased the risk for intrauterine infection only when present in combination with other RTIs (p =0.023). Conclusion. Histological placental inflammation is associated with both BV and genital tract colonisation with aerobic bacteria, while funisitis is associated with colonisation of aerobic bacteria at first prenatal visit before the 17th gestational week.
Surveillance for Catheter-Associated Bloodstream Infection in Hematology Units: Quantifying the Characteristics of a Practical Case Definition
Authors: Worth Leon J. , Black James , Seymour John F. , Thursky Karin A. , Slavin Monica A.
Published: February 2008

We evaluated 66 patients in a hematology unit, who used a total of 106 central venous catheters (CVCs), to identify CVC-associated bloodstream infections using standard and modified surveillance case definitions. Compared with the National Nosocomial Infection Surveillance system criteria, a modified case definition used by treating physicians demonstrated 100.0% sensitivity and 94.3% specificity. This case definition provides a practical method for effectively excluding CVC-associated bloodstream infection.
Bloodstream Infections in Patients Given Treatment With Intravenous Prostanoids
Authors: Kallen Alexander J. , Lederman Edith , Balaji Alexandra , Trevino Ingrid , Petersen Emily E. , Shoulson Rivka , Saiman Lisa , Horn Evelyn M. , Gomberg-Maitland Mardi , Barst Robyn J. , Srinivasan Arjun
Published: February 2008

Objective.

In September 2006, the Centers for Disease Control and Prevention was notified of cases of gram-negative bloodstream infection (BSI) occurring among outpatients who received an intravenous formulation of the prostanoid treprostinil. An investigation was conducted to determine rates of prostanoid-associated BSI in this patient population and possible risk factors for infection.

Methods.

We performed a retrospective cohort study of patients who had received intravenous formulations of at least 1 of the 2 approved prostanoids (epoprostenol and treprostinil) from January 1, 2004, through late 2006. Chart reviews were conducted at 2 large centers for pulmonary arterial hypertension, and a survey of infection control practices was conducted at 1 center.

Results.

A total of 224 patients were given intravenous prostanoid treatment, corresponding to 146,093 treatment-days during the study period. Overall, there were 0.55 cases of BSI and 0.18 cases of BSI due to gram-negative organisms per 1,000 treatment-days. BSI rates were higher for patients who received intravenous treprostinil than for patients who received intravenous epoprostenol (1.13 vs. 0.42 BSIs per 1,000 treatment-days; P < .001), as were rates of BSI due to gram-negative organisms (0.81 vs. 0.04 BSIs per 1,000 treatment-days; P < .001). Adjusted hazard ratios for all BSIs and for BSIs due to gram-negative organisms were higher among patients given treatment with intravenous treprostinil. The survey identified no significant differences in medication-related infection control practices.

Conclusion.

At 2 centers, BSI due to gram-negative pathogens was more common than previously reported and was more frequent among patients given treatment with intravenous treprostinil than among patients given treatment with intravenous epoprostenol. Whether similar results would be found at other centers for pulmonary arterial hypertension warrants further investigation. This investigation underscores the importance of surveillance and evaluation of healthcare-related adverse events in patients given treatment primarily as outpatients.