bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Harris current sheet thickness from Cluster current density and plasma measurements
Authors: Thompson S. M. , Kivelson M. G. , Khurana K. K. , McPherron R. L. , Weygand J. M. , Balogh A. , Réme H. , Kistler L. M.
Published: February 2005

We use the first accurate measurements of current densities in the plasma sheet to calculate the half‐thickness and position of the current sheet as a function of time. Our technique assumes a Harris current sheet model, which is parameterized by lobe magnetic field B0, current sheet half‐thickness h, and current sheet position z0. Cluster measurements of magnetic field, current density, and plasma pressure are used to infer the three parameters as a function of time. We find that most long timescale (6–12 hours) current sheet crossings observed by Cluster cannot be described by a static Harris current sheet with a single set of parameters B0, h, and z0. Noting the presence of high‐frequency fluctuations that appear to be superimposed on lower frequency variations, we average over running 6‐min intervals and use the smoothed data to infer the parameters h(t) and z0(t), constrained by the pressure balance lobe magnetic field B0(t). Whereas this approach has been used in previous studies, the spatial gradients now provided by the Cluster magnetometers were unavailable or not well constrained in earlier studies. We place the calculated half‐thicknesses in a magnetospheric context by examining the change in thickness with substorm phase for three case study events and 21 events in a superposed epoch analysis. We find that the inferred half‐thickness in many cases reflects the nominal changes experienced by the plasma sheet during substorms (i.e., thinning during growth phase, thickening following substorm onset). We conclude with an analysis of the relative contribution of ∂BZ/∂X to the cross‐tail current density during substorms. We find that ∂BZ/∂X can contribute a significant portion of the cross‐tail current around substorm onset.
Glycoprotein‐specific ubiquitin ligases recognize N‐glycans in unfolded substrates
Authors: Yoshida Yukiko , Adachi Eru , Fukiya Kanako , Iwai Kazuhiro , Tanaka Keiji
Published: February 2005

Misfolded or unassembled polypeptides in the endoplasmic reticulum (ER) are retro‐translocated into the cytosol and degraded by the ubiquitin–proteasome system. We reported previously that the SCFFbs1,2 ubiquitin‐ligase complexes that contribute to ubiquitination of glycoproteins are involved in the ER‐associated degradation pathway. Here we investigated how the SCFFbs1,2 complexes interact with unfolded glycoproteins. The SCFFbs1 complex was associated with p97/VCP AAA ATPase and bound to integrin‐β1, one of the SCFFbs1 substrates, in the cytosol in a manner dependent on p97 ATPase activity. Both Fbs1 and Fbs2 proteins interacted with denatured glycoproteins, which were modified with not only high‐mannose but also complex‐type oligosaccharides, more efficiently than native proteins. Given that Fbs proteins interact with innermost chitobiose in N‐glycans, we propose that Fbs proteins distinguish native from unfolded glycoproteins by sensing the exposed chitobiose structure.
Resetting of peripheral circadian clock by prostaglandin E2
Authors: Tsuchiya Yoshiki , Minami Itsunari , Kadotani Hiroshi , Nishida Eisuke
Published: February 2005

In mammals, the master circadian pacemaker is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN is thought to drive peripheral oscillators by controlling neuronal and humoral signals that can entrain the peripheral clocks. Here, we show that prostaglandin E2 (PGE2), a proinflammatory compound known to have diverse biological effects, is able to act as an in vivo clock‐resetting agent. We find that in cultured NIH3T3 fibroblasts, PGE2 is able to induce transient expression of Period 1 messenger RNA and the following circadian oscillation of clock gene expression. Furthermore, we demonstrate that intraperitoneal administration of PGE2 results in the phase shift of circadian gene expression in mouse peripheral tissues in a time‐dependent manner. This phase shift is also induced by the EP1/EP3 agonist sulprostone but not by the EP2 agonist butaprost. The PGE2‐induced phase shift is inhibited by the EP1 antagonist SC‐51322. These results suggest that PGE2 acts as an in vivo clock‐resetting factor by means of the EP1 subtype of PGE receptors.
An Arabidopsis aspartic protease functions as an anti‐cell‐death component in reproduction and embryogenesis
Authors: Ge Xiaochun , Dietrich Charles , Matsuno Michiyo , Li Guojing , Berg Howard , Xia Yiji
Published: February 2005

The components and pathways that regulate and execute developmental cell death programmes in plants remain largely unknown. We have found that the PROMOTION OF CELL SURVIVAL 1 (PCS1) gene in Arabidopsis, which encodes an aspartic protease, has an important role in determining the fate of cells in embryonic development and in reproduction processes. The loss‐of‐function mutation of PCS1 causes degeneration of both male and female gametophytes and excessive cell death of developing embryos. Conversely, ectopic expression of PCS1 causes the septum and stomium cells that normally die in the anther wall to survive instead, leading to a failure in anther dehiscence and male sterility. PCS1 provides a new avenue for understanding the mechanisms of the programmed cell death processes that are associated with developmental pathways in plants and makes available a useful tool for engineering the male sterility trait for hybrid seed production.
Wnt, stem cells and cancer in the intestine
Authors: Pinto Daniel , Clevers Hans
Published: February 2005

The intestinal epithelium is a self‐renewing tissue which represents a unique model for studying interconnected cellular processes such as proliferation, differentiation, cell migration and carcinogenesis. Although the stem cells of the intestine have not yet been physically characterized or isolated, data over the past decade have strongly implicated the Wnt/β‐catenin signalling pathway in their maintenance and progression to cancer. This review will (i) describe the distinctive features of the intestinal epithelium in relation to stem‐cell function, (ii) illustrate the major genetic alterations that can lead to cancer, and (iii) show how Wnt/β‐catenin signalling controls homoeostasis in this tissue.
Role of cytokines in cardiovascular diseases: a focus on endothelial responses to inflammation
Authors: KOFLER Sieglinde , NICKEL Thomas , WEIS Michael
Published: February 2005

Complex cellular and inflammatory interactions are involved in the progress of vascular diseases. Endothelial cells, upon exposure to cytokines, undergo profound alterations of function that involve gene expression and de novo protein synthesis. The functional reprogramming of endothelial cells by cytokines is of importance especially in patients with chronic vascular inflammation. The intercellular network of dendritic cells, T-lymphocytes, macrophages and smooth muscle cells generates a variety of stimulatory cytokines [e.g. TNF-α (tumour necrosis factor-α), IL (interleukin)-1, IL-6 and IFN-γ (interferon-γ)] and growth factors that promote the development of functional and structural vascular changes. High concentrations of proinflammatory cytokines increase oxidative stress, down-regulate eNOS (endothelial nitric oxide synthase) bioactivity and induce endothelial cell apoptosis. Chemoattractant cytokines [e.g. VEGF (vascular endothelial growth factor), TGF-β1 (transforming growth factor-β1) and IL-8] are important regulators of inflammation-induced angiogenesis and are directly modulated by nitric oxide. This review will focus on the vascular mechanisms orchestrated by cytokines and summarizes the current knowledge concerning the contribution of cytokines to cardiovascular diseases.
Effects of a dual endothelin-1 receptor antagonist on airway obstruction and acute lung injury in sheep following smoke inhalation and burn injury
Authors: COX Robert A. , ENKHABAATAR Perenlei , BURKE Ann S. , KATAHIRA Jiro , SHIMODA Katahiro , CHANDRA Abhijit , TRABER Lillian D. , HERNDON David N. , HAWKINS Hal K. , TRABER Daniel L.
Published: February 2005

Studies have suggested that ET-1 (endothelin-1) is associated with lung injury, airway inflammation and increased vascular permeability. In the present study we have tested the hypothesis that treatment with a dual ET-1 receptor antagonist will decrease airway obstruction and improve pulmonary function in sheep with combined S+B (smoke inhalation and burn) injury. Twelve sheep received S+B injury using the following protocol: six sheep were treated with tezosentan, an ETA and ETB receptor antagonist, and six sheep received an equivalent volume of vehicle. Physiological and morphological variables were assessed during the 48 h study period and at the end of the study. There was no statistically significant difference in the PaO2/FiO2 (partial pressure of O2 in arterial blood/fraction of O2 in the inspired gas) ratio of the tezosentan-treated animals compared with controls; however, lung lymph flow was significantly higher (P<0.05) in the treated animals. PVRI (pulmonary vascular resistance index) was significantly reduced (P<0.05) in the tezosentan-treated animals. Assessment of NOx (nitric oxide metabolite) levels in plasma and lymph showed significantly elevated (P<0.05) levels in the tezosentan-treated animals compared with levels in untreated sheep. The degree of bronchial obstruction was similar in both treated and control sheep; however, bronchiolar obstruction was reduced in sheep treated with tezosentan. Histopathologically, no difference in the degree of parenchymal injury was detected. In conclusion, administration of a dual ET-1 receptor antagonist prevented an increase in PVRI after injury and reduced the degree of bronchiolar obstruction in sheep with S+B; however, treated sheep showed higher levels of NOx and increased lung lymph flow. Tezosentan treatment was ineffective in protecting against acute lung injury in this model.
Factor VIIa stimulates endothelin-1 synthesis in TNF-primed endothelial cells by activation of protease-activated receptor 2
Authors: SETHI Amarjit S. , LEES Delphine M. , DOUTHWAITE Julie A. , CORDER Roger
Published: February 2005

The mechanisms linking prothrombotic changes to endothelial dysfunction and accelerated atheroma formation have yet to be fully defined. Expression of TF (tissue factor) on the endothelium is potentially an initiating event as binding and activation of FVII (factor VII) can result in thrombosis. Although PAR2 (protease-activated receptor-2) is expressed on vascular endothelium, its precise physiological significance and mechanism of activation have yet to be defined. In the present study, we investigated whether PAR2 can be activated by FVIIa (activated FVII) and induce ET-1 (endothelin-1) synthesis. In bovine aortic endothelial cells pretreated with TNF (tumour necrosis factor-α) to increase TF expression, FVIIa stimulated ET-1 synthesis via activation of PAR2. Although FX (factor X) alone was inactive, this response was enhanced by using FVII and FX in combination. Inhibition of the proteolytic activity of FVIIa abolished the response. The PAR2 agonist peptide SLIGKV also enhanced ET-1 release on TNF-pretreated cells. The response to FVIIa was inhibited by a PAR2 antagonist peptide FSLLRY. Inhibition of the p38 MAPK (mitogen-activated protein kinase) reduced PAR2 expression and the ET-1 response. In summary, FVIIa can stimulate ET-1 synthesis in endothelial cells by activating PAR2, demonstrating a potential link between thrombotic processes and endothelial cell dysfunction.
Regulation of reactive oxygen species (ROS) production by C18 fatty acids in Jurkat and Raji cells
Authors: CURY-BOAVENTURA Maria F. , CURI Rui
Published: February 2005

In the present study, the effects of C18 fatty acids with different numbers of double bonds, SA (stearic acid; C18:0), OA (oleic acid; C18:1), LA (linoleic acid; C18:2) and γ-LNA (γ-linolenic acid; C18:3), on ROS (reactive oxygen species) production by Jurkat (a human T-lymphocyte-derived cell line) and Raji (a human B-lymphocyte-derived cell line) cells were investigated. ROS production was determined by NBT (Nitro Blue Tetrazolium) reduction (intracellular and extracellular ROS production) and by dihydroethidium oxidation using flow cytometry (intracellular ROS production). The effectiveness on ROS production was γ-LNA<SA<OA<LA in Jurkat cells and SA<γ-LNA<OA<LA in Raji cells. LA (found in corn, soya bean and sunflower oils) was more potent than OA (found in olive oil) in stimulating ROS production in both Raji and Jurkat cells. The lower ROS production by OA compared with LA may be one of the benefits of olive oil consumption. As SA and γ-LNA acids had little or no effect, further studies on the site of ROS production in these cells were carried out with OA and LA only. Activation of NADPH oxidase via PKC (protein kinase C) was found to be the major mechanism of ROS production induced by OA and LA in Jurkat and Raji cells.
Short-term blood pressure and heart rate variability in congenital central hypoventilation syndrome (Ondine's curse)
Authors: TRANG Ha , GIRARD Arlette , LAUDE Dominique , ELGHOZI Jean-Luc
Published: February 2005

The effect of CCHS (congenital central hypoventilation syndrome, or Ondine's curse) on short-term BP (blood pressure) and HR (heart rate) variability was evaluated in 16-year-old subjects presenting a form of CCHS requiring night ventilatory assistance. The 12 patients were compared with 12 age- and gender-matched healthy volunteers. Recordings were obtained during daytime while the subjects were breathing spontaneously. Continuous BP was measured with a Finapres® device in the supine, head-up tilt and standing positions. The manoeuvre of actively standing was also analysed. HR levels were elevated in CCHS subjects at supine rest (+23%) with a reduced HR overall variability (−88%). The low- and high-frequency components of HR variability were affected. BP levels were preserved at rest, but the manoeuvres demonstrated a limited capacity to elevate BP. There was no overshoot in BP during the manoeuvre of actively standing, and steady standing BP levels in patients were not higher than supine BP levels as usually observed in healthy controls. The spontaneous baroreflex sensitivity estimated using the sequence technique or the cross-spectral analysis fell in the patients to approx. one-third of the sensitivity estimated in the healthy controls whatever the position. This cardiovascular profile suggests a predominant vagal dysfunction with signs of vagal withdrawal and baroreflex failure, and relative preservation of the cardiac and vascular sympathetic function. It is likely that the impaired ontogeny of the visceral reflexes, considered now to cause CCHS syndrome, includes the baroreceptive pathway and mainly its vagal component.
Winged-helix transcription factors and pancreatic development
Authors: LANTZ Kristen A. , KAESTNER Klaus H.
Published: February 2005

The forkhead gene family, named after the founding gene member in Drosophila, is characterized by a unique DNA-binding domain. This so-called forkhead box encodes a winged-helix DNA-binding motif, the name of which describes the structure of the domain when bound to DNA. The three Fox (forkhead box) group A genes, Foxa1, Foxa2 and Foxa3, are expressed in embryonic endoderm, the germ layer that gives rise to the digestive system, and contribute to the specification of the pancreas and the regulation of glucose homoeostasis. Deletion of the Foxa2 gene in pancreatic β-cells in mice results in a phenotype resembling PHHI (persistent hyperinsulinaemic hypoglycaemia of infancy). Molecular analyses have demonstrated that Foxa2 is an important regulator of the genes encoding Sur1, Kir6.2 and Schad (short chain L-3-hydroxyacyl-CoA dehydrogenase), mutation of which causes PHHI in humans. Foxa1 was shown to be an essential activator of glucagon gene expression in vivo. An additional winged-helix protein, Foxo1, contributes to pancreatic β-cell function by regulating the Pdx1 gene, which is required for pancreatic development in cooperation with Foxa2.
High resolution infrared spectra of H2–Kr and D2–Kr van der Waals complexes
Authors: McKellar A. R. W.
Published: February 2005

Infrared spectra of weakly bound hydrogen–krypton complexes have been studied at high spectral resolution (0.04cm−1) using a long-path (154m) low temperature (100K) absorption cell and a Fourier transform spectrometer. In addition to spectra from the regions of the H2 and D2 fundamental vibrational bands in the midinfrared, the results also include the region of the pure rotational S0(0) transition of H2 in the far infrared. A total of 219 measured line positions from these spectra have been fully assigned to specific quantum transitions and form the basis for determining a greatly improved semiempirical three-dimensional intermolecular potential energy surface for hydrogen–krypton in an accompanying paper.
Correlated holes and their relationships with reduced density matrices and cumulants
Authors: Bochicchio R. C. , Torre A. , Lain L.
Published: February 2005

This paper describes a matrix formulation for the correlated hole theory within the framework of the domain-averaged model in many electron systems (atoms, molecules, condensed matter, etc.). General relationships between this quantity and one-particle reduced density matrices for any independent particle or correlated state functions are presented. This formulation turns out to be suitable for computational purposes due to the straightforward introduction of cumulants of two-particle reduced density matrices within the quantum field structure. Numerical calculations in selected simple molecular systems have been performed in order to determine preliminary correlated values for such a quantity.
Multispecies ion acceleration off laser-irradiated water droplets
Authors: Kemp A. J. , Ruhl H.
Published: February 2005

In a recent experiment at Max-Born Institut, Berlin, strong modulations have been observed in energy spectra of MeV ions that were accelerated by ultrashort intense laser pulses, τL=35fs, I=1019W∕cm2, off water droplets. This experiment is studied analytically as well as by numerical particle-in-cell simulations in one and two dimensions and it is shown how classical isothermal fluid expansion models fail in the present case. The paper investigates alternative models which claim to describe the ion spectral modulations and a mechanism that generates proton spectra similar to the experimental ones due to a simultaneous acceleration of several ion components. Finally, the issue of directional anisotropy in the spectra of accelerated ions for the case of a spherical target is discussed.
Automated tracking and laser micromanipulation of motile cells
Authors: Stuhrmann B. , Gögler M. , Betz T. , Ehrlicher A. , Koch D. , Käs J.
Published: February 2005

Control over neuronal growth is a prerequisite for the creation of defined in vitro neuronal networks as assays for the elucidation of interneuronal communication. Neuronal growth has been directed by focusing a near-infrared laser beam at a nerve cell’s leading edge [A. Ehrlicher, T. Betz, B. Stuhrmann, D. Koch, V. Milner, M. G. Raizen, and J. Käs, Proc. Natl. Acad. Sci. U.S.A. 99, 16024 (2002)]. The setup reported by Ehrlicher et al. was limited to local laser irradiation and relied on a great deal of subjective interaction since the laser beam could only be steered manually. To overcome the drawbacks of the reported setup, we developed and here present a fully automated low-contrast edge detection software package, which responds to detected cell morphological changes by rapidly actuating laser steering devices, such as acousto-optical deflectors or moving mirrors, thus enabling experiments with minimum human interference. The resulting radiation patterns can be arbitrary functions of space, time, and cell morphology, and are calculated by experiment specific feedback routines. Data processing is repeated on the order of 1s allowing rapid reactions to morphological changes. The strengths of our program are the combination of real-time low contrast shape detection with complex feedback mechanisms, as well as easy adaptability due to a modular programming concept. In this article we demonstrate automated optical guidance; however, the software is easily adaptable to other problems requiring automated rapid responses of equipment to changes in the morphology of low contrast objects.
Effect of tensile offset angles on micro/nanoscale tensile testing
Authors: Li Xiaodong , Wang Xinnan , Chang Wei-Che , Chao Yuh J. , Chang Ming
Published: February 2005

For one-dimensional (1D) structures such as tubes, wires, and beams, tensile testing is a simple and reliable methodology for measuring their mechanical properties. The tensile offset angle effect on mechanical property measurement has long been ignored. In this study, theoretical and finite-element analysis (FEA) models for analyzing the tensile offset angle effect have been established. It is found that longitudinal stress decreases with increasing offset angles. The theoretically calculated elastic modulus relative errors reach 4.45% at the offset angle of 10°, whereas the experimentally measured elastic modulus relative errors are 45.4% at the offset angle of 15°. The difference in elastic modulus relative errors between the theoretical analysis and the experimental results is discussed with reference to the sensing system in the experimental instrumentation. To accurately measure the mechanical properties using the tensile testing technique, perfect alignment with a zero or small offset angle less than 5° is needed. A calibration methodology for aligning specimens has been developed.
High-power frequency-stabilized laser for laser cooling of metastable helium at 389 nm
Authors: Koelemeij J. C. J. , Hogervorst W. , Vassen W.
Published: February 2005

A high-power, frequency-stabilized laser for cooling of metastable helium atoms using the 2S13→3P23 transition at 389 nm has been developed. The 389 nm light is generated by frequency doubling of a titanium:sapphire laser in an external enhancement cavity containing a lithium–triborate nonlinear crystal. With a maximum conversion efficiency of 75%, 1 W of useful 389 nm power is produced out of 2 W at 778 nm. While being stabilized to the 2S13→3P23 transition, the 389 nm frequency is tunable over ±150MHz with respect to the field-free atomic resonance frequency. This is accomplished by Zeeman tuning of the absorption lines used in the frequency-stabilization scheme. The setup for saturated absorption spectroscopy in an rf discharge cell, used to stabilize the 389 nm laser to the atomic transition, is described in detail.
Aerodynamic force measurement on a large-scale model in a short duration test facility
Authors: Tanno H. , Kodera M. , Komuro T. , Sato K. , Takahasi M. , Itoh K.
Published: February 2005

A force measurement technique has been developed for large-scale aerodynamic models with a short test time. The technique is based on direct acceleration measurements, with miniature accelerometers mounted on a test model suspended by wires. Measuring acceleration at two different locations, the technique can eliminate oscillations from natural vibration of the model. The technique was used for drag force measurements on a 3m long supersonic combustor model in the HIEST free-piston driven shock tunnel. A time resolution of 350μs is guaranteed during measurements, whose resolution is enough for ms order test time in HIEST. To evaluate measurement reliability and accuracy, measured values were compared with results from a three-dimensional Navier–Stokes numerical simulation. The difference between measured values and numerical simulation values was less than 5%. We conclude that this measurement technique is sufficiently reliable for measuring aerodynamic force within test durations of 1ms.
Effects of sample thickness on the van der Pauw technique for resistivity measurements
Authors: Kasl C. , Hoch M. J. R.
Published: February 2005

The van der Pauw technique is commonly used for electrical transport measurements on solid materials and is suited to thin, arbitrarily shaped samples, with the contacts placed anywhere on the periphery. Previous investigations have determined the effects of sample shape, contact size, and contact placement on the accuracy of this technique. Sample inhomogeneity effects have also been investigated. The effects of the sample thickness appear not to have been previously studied and are investigated here in order to establish precisely what is meant by a thin sample. The deterioration in the accuracy of the technique is followed as the sample thickness is increased. The results indicate that the van der Pauw technique may be used for samples where the thickness is comparable to the surface dimensions. The investigation also shows that the technique is valid for arbitrarily thick samples provided that low resistance electrodes are placed across the entire edge, perpendicular to the surface, in order to maintain an effective two-dimensional current distribution. This finding is useful for transport measurements on materials that have been prepared, for example, by solid state reaction using sintering methods.
Millimeter-wave scanning near-field anisotropy microscopy
Authors: Nozokido Tatsuo , Iibuchi Ryohei , Bae Jongsuck , Mizuno Koji , Kudo Hiroyuki
Published: February 2005

A millimeter-wave scanning near-field microscopy using a slit-type probe, which permits the observation of electrical anisotropy in the viewed object, is proposed. The slit probe is sensitive to any electrical anisotropy along the object surface direction that is inherent in the object to be imaged, because the electric field at its aperture is linearly polarized. An electrical anisotropy model is incorporated into the image reconstruction process that enables two-dimensional image reconstruction. The details of the model and the reconstruction method adopted in this work are described and experimental results to demonstrate the feasibility of this microscopy format are presented.
Investigation of Mg doping in high-Al content p-type AlxGa1−xN (0.3<x<0.5)
Authors: Jeon S.-R. , Ren Z. , Cui G. , Su J. , Gherasimova M. , Han J. , Cho H.-K. , Zhou L.
Published: February 2005

A study of Mg doping of AlxGa1−xN up to x∼50% using microstructural and electrical probes is reported. The viability of effective p-type doping is defined by a minimum concentration of Mg required to offset the background impurities and, more importantly, a maximum limit above which inversion domains and structural defects start to nucleate, accompanied by a rapid degradation of electrical transport. Resistivity of 10 Ω cm and free hole concentrations above 1017cm−3 are achieved for AlxGa1−xN up to x∼50% within an optimum window of Mg incorporation.
Time-resolved and time-integrated photoluminescence studies of coupled asymmetric GaN quantum discs embedded in AlGaN barriers
Authors: Na J. H. , Taylor R. A. , Rice J. H. , Robinson J. W. , Lee K. H. , Park Y. S. , Park C. M. , Kang T. W.
Published: February 2005

We have investigated exciton dynamics in asymmetric GaN quantum discs embedded in AlGaN barriers with an Al content of 50% using time-integrated and time-resolved micro-photoluminescence measurements. Emission from the quantum discs emerges at lower energy than that from the GaN nanocolumns, which suggests that GaN quantum discs are strongly affected by the built-in electric field. The lifetimes of localized excitons in quantum discs were obtained. Nonlinear emission from quantum discs under high excitation power was attributed to tunneling of carriers to larger discs from smaller discs.
Scanning electron microscopy cathodoluminescence studies of piezoelectric fields in an InGaN∕GaN quantum-well light-emitting diode
Authors: Bunker K. L. , Garcia R. , Russell P. E.
Published: February 2005

Scanning electron microscopy (SEM) cathodoluminescence (CL) experiments were used to determine the existence and direction of piezoelectric fields in a commercial InGaN multiple-quantum-well (MQW) light-emitting diode (LED). The CL emission peak showed a blueshift with increasing reverse bias due to the cancellation of the piezoelectric field. A full compensation of the piezoelectric field was observed followed by a redshift with a further increase of reverse bias, indicating that flat-band conditions had been reached. We determined the piezoelectric field points in the [000-1] direction and estimated the magnitude to be approximately 1MV∕cm. SEM-CL carrier generation density variation and electroluminescence experiments were also used to confirm the existence of a piezoelectric field in the InGaN MQW LED.
Conductivity mechanism analysis at high temperature in bismuth titanate: A single crystal with sillenite-type structure
Authors: Lanfredi S. , Nobre M. A. L.
Published: February 2005

Conductivity behavior of the Bi12TiO20 single crystal was investigated by the electric modulus spectroscopy, which was carried out in the frequency range from 5 Hz to 13 MHz and at temperatures higher than 400 °C. The resistance curve exhibits a set of properties correlated to a negative temperature coefficient thermistor. In the temperature range investigated, the characteristic parameter (β) of the thermistor is equal to 4834 °C. Temperature coefficients of the resistance (α) were derived being equal to −3.02×10−2°C−1 at 400 °C and equal to −9.86×10−3°C−1 at 700 °C. The nature of the electric relaxation phenomenon and magnitude dc conductivity are approached.
Copper-phthalocyanine-based organic solar cells with high open-circuit voltage
Authors: Singh V. P. , Singh R. S. , Parthasarathy B. , Aguilera A. , Anthony J. , Payne M.
Published: February 2005

We report on a copper phthalocyanine (CuPc)/3,4,9,10 perylenetetracarboxylic bisbenzimidazole (PTCBI) organic solar cell with an aluminum cathode exhibiting an open-circuit voltage (VOC) of 1150 mV and a short-circuit current density (JSC) of 0.125mA∕cm2. For comparison, aluminum and silver were used as electrode materials and their effects on device characteristics were studied; silver yielded lower VOC but higher JSC and higher efficiency. Results could be understood through a model that hypothesized surface modification of CuPc by PTCBI and the formation of a thin insulating layer between aluminum and PTCBI when aluminum was used as electrode.
Ecosystem services: an ecophysiological examination
Authors: Eamus Derek , Macinnis-Ng Catriona M. O. , Hose Grant C. , Zeppel Melanie J. B. , Taylor Daniel T. , Murray Brad R.
Published: February 2005

This review aims to discuss ecosystem services, provide illustrative case studies at catchment and local scales and present future research needs. This review discusses the following: (1) Ecosystem services (ES) are those goods and services that are provided by or are attributes of ecosystems that benefit humans. Examples of ES include the timber derived from a forest, the prevention of soil and coastal erosion by vegetation and the amelioration of dryland salinity through prevention of rises in the water table by trees. The provision of ES globally is in decline because of a lack of awareness of the total economic value of ES in the public, policy and political fora. (2) Providing a scientific understanding of the relationships among ecosystem structure, function and provision of ES, plus determining actual economic value of ES, are the central challenges to environmental scientists (including triple-bottom-line economists). (3) Some ES are widely dispersed throughout many different ecosystems. Carbon accumulation in trees and the contribution of biodiversity to ES provision are two examples of highly dispersed attributes common to many ecosystems. In contrast, other ES are best considered within the context of a single defined ecosystem (although they may occur in other ecosystems too). Mangroves as ‘nursery’ sites for juvenile fish is one example. (4) Examples of catchment-scale and local-scale provision of ES are discussed, along with future research issues for the nexus between ES and environmental sciences.
Lag-1 sparing in the attentional blink: Benefits and costs of integrating two events into a single episode
Authors: Hommel Bernhard , Akyürek Elkan G.
Published: February 2005

When people monitor a visual stream of rapidly presented stimuli for two targets (T1 and T2), they often miss T2 if it falls into a time window of about half a second after T1 onset—the attentional blink. However, if T2 immediately follows T1, performance is often reported being as good as that at long lags—the so-called Lag-1 sparing effect. Two experiments investigated the mechanisms underlying this effect. Experiment 1 showed that, at Lag 1, requiring subjects to correctly report both identity and temporal order of targets produces relatively good performance on T2 but relatively bad performance on T1. Experiment 2 confirmed that subjects often confuse target order at short lags, especially if the two targets are equally easy to discriminate. Results suggest that, if two targets appear in close succession, they compete for attentional resources. If the two competitors are of unequal strength the stronger one is more likely to win and be reported at the expense of the other. If the two are equally strong, however, they will often be integrated into the same attentional episode and thus get both access to attentional resources. But this comes with a cost, as it eliminates information about the targets’ temporal order.
Stimulus similarity decrements in children's working memory span
Authors: Conlin Juliet A. , Gathercole Susan E. , Adams John W.
Published: February 2005

Two experiments investigated the impact of the relationship between processing and storage stimuli on the working memory span task performance of children aged 7 and 9 years of age. In Experiment 1, two types of span task were administered (sentence span and operation span), and participants were required to recall either the products of the processing task (sentence-final word, arithmetic total) or a word or digit unrelated to the processing task. Experiment 2 contrasted sentence span and operation span combined with storage of either words or digits, in tasks in which the item to be remembered was not a direct product of the processing task in either condition. In both experiments, memory span was significantly greater when the items to be recalled belonged to a different stimulus category from the material that was processed, so that in sentence span tasks, number recall was superior to word recall, and in operation span tasks, word recall was superior to number recall. Explanations of these findings in terms of similarity-based interference and response competition in working memory are discussed.
By which name should I call thee? The consequences of having multiple names
Authors: Stevenage Sarah V. , Lewis Hugh G.
Published: February 2005

The nominal competitor effect suggests that, when a person has two names associated with them, recall of either name is more difficult than if they just had one name. Drawing on a connectionist framework, this effect could arise either if multiple names were represented as being connected to a single person identity node (PIN), or if multiple names were represented as being connected via one-to-one links to multiple PINs. Whilst the latter has intuitive appeal, results from two experiments support the former architecture. Having two names connected to a single PIN not only gives rise to a nominal competitor effect (Experiment 1), but also gives rise to a familiarity enhancement effect (Experiment 2). These empirical results are simulated using an extension of Brédart, Valentine, Calder, and Gassi's (1995) connectionist architecture, which reveals that both effects hold even when the association of both names to the PIN is unequal. These results are presented in terms of a more complete model for person recognition, and the representation of semantic information within such a model is examined.
The association of employment status and family status with health among women and men in four Nordic countries
Authors: Roos E. , Lahelma E. , Saastamoinen P. , Elstad J.-I.
Published: February 2005

Aims: The Nordic countries have relatively equal employment participation between men and women, but some differences between countries exist in labour market participation. The aim was to examine the association between employment status and health among women and men in Denmark, Finland, Norway, and Sweden, and analyse whether this association is modified by marital status and parental status. Methods: The data come from nationally representative cross-sectional surveys carried out in Denmark (n=2,209), Finland (n=4,604), Norway (n=1,844) and Sweden (n=5,360) in 1994—95. Women and men aged 25—49 were included. Employment status was categorized into full-time employed, part-time employed, unemployed, and housewives among women and into employed and unemployed among men. Health was measured by perceived health and limiting longstanding illness. Logistic regression analysis was used, adjusting for age and education. Marital status and parental status were analysed as modifying factors. Results: The non-employed were more likely to report perceived health as below good and limiting longstanding illness than the employed among both women and men. The association between employment status and perceived health remained unchanged when marital status and parental status were adjusted for among all men and Finnish women, but the association was slightly strengthened among Danish and Swedish women, with the housewives becoming more likely to report ill health than employed women. The association between employment status and limiting longstanding illness was slightly strengthened among women, and slightly weakened among Norwegian men when marital and parental status were adjusted for. Conclusions: Non-employment was associated with poorer health in all countries, although there are differences in the employment patterns between the countries. Among women marital status and parental status showed a modest or no influence on the association between employment status and health. Among men there was no such influence.
Low socioeconomic status is associated with chronic musculoskeletal complaints among 46,901 adults in Norway
Authors: Hagen Knut , Zwart John-Anker , Svebak Sven , Bovim Gunnar , Stovner Lars Jacob
Published: February 2005

Aims: A study was undertaken to evaluate the relationship between socioeconomic status (SES) and chronic musculoskeletal complaints (MSC), and to determine how this relationship is influenced by change in SES. Methods: Two consecutive public health surveys within the county of Nord-Trøndelag, Norway, were conducted in 1984—86 (HUNT-1) and 1995—97 (HUNT-2). Among 46,901 adults who participated in both surveys, 24,127 persons (51%) in HUNT-2 who reported MSC continuously for at least 3 months during the past year were defined as having chronic MSC. Prevalence of chronic MSC was estimated at nine anatomical sites using multiple logistic regression with odds ratio (OR) and 95% confidence interval (CI) as measures of association with SES. Results: When defining SES by educational level, type of occupation, or income, low status was associated with increased prevalence of chronic MSC (age-adjusted analyses). The negative influence of low education or low occupation level was not eliminated by increasing the level of education or occupation from HUNT-1 to HUNT-2, in contrast with what was found for individuals with higher income level in HUNT-2 than in HUNT-1. The relationship with SES was more evident among individuals with musculoskeletal symptoms≥15 days during the past month than among those with less than 15 days, evident at all nine different anatomical sites. The strongest relationship was found between low SES and prevalence of widespread chronic MSC. Conclusions: Individuals with low SES had higher prevalence of chronic MSC than those with high SES. Future studies should try to clarify whether chronic MSC are a cause or consequence of low SES.
Prognosis of risk factors and trends in mortality from external causes among middle-aged men in Lithuania
Authors: Tamosiunas Abdonas , Reklaitiene Regina , Radisauskas Ricardas , Jureniene Kristina
Published: February 2005

Aims: The aims of this study were to investigate the risk of death and time trends from external causes, and to evaluate the significance of the effects of age, period and birth cohort on suicide mortality among middle-aged men during the period 1971—2000 in Lithuania. Methods: Random samples of men aged 45—59 years from the Kaunas Rotterdam Intervention Study (conducted in 1972—74) and Study of Multifactorial Prevention of CHD (conducted in 1977—80) were examined (n=6,480). The participants of the two surveys were observed until 1 January 2001. Over this time 2,841 men had died, 230 of these from external causes. The Cox proportional hazards model was used to evaluate the risk of death from external causes. Trends in mortality from external causes and average annual changes were based on logarithmic regression analysis. For assessment of the effects of age, period, and birth cohort the Poisson regression model was applied. Results: The risk of mortality from external causes among men was positively related to smoking habits and arterial hypertension and negatively related to education level and total serum cholesterol concentration but there was no association with consumption of alcohol. The risk of suicide mortality was associated with family status and occupation only. Trends in mortality from all external causes showed no significant changes during the period 1971—2000. After adjusting for age and cohort effects, the period effect was statistically significant. Conclusion: Prognosis of risk factors for mortality from external causes and period effect on suicide mortality rates will form important parts of future research agendas.
Willingness to pay for hypothetical malaria vaccines in rural Burkina Faso
Authors: Sauerborn Rainer , Gbangou Adjima , Hengjin Dong  , Przyborski Jude M. , Lanzer Michael
Published: February 2005

Aims: This study aims to set priorities for anti-disease malaria vaccines by determining community preference in a hyperendemic area. Methods: A bidding game technique was used to elucidate willingness to pay in rural Burkina Faso and 2,326 adults were interviewed. Results: It is shown that there are significant differences between community preference for an anti-disease vaccine aimed at reducing pathology in pregnant women, and for a vaccine directed against childhood malaria. While the target population was willing to pay CFAfr 2101 for a vaccine against maternal malaria, its members were prepared to pay only CFAfr 1433 for a vaccine against childhood malaria. Conclusions: Whilst it is increasingly likely that anti-disease malaria vaccines will become available in the foreseeable future, lessons from the past suggest that a lack of acceptance and support from the intended recipients may lead to less than optimal compliance, and hence efficacy. For the planning of vaccine development and application strategies, it is therefore highly important to take community views into account. Here it is argued that such information could help researchers and funding agencies to set priorities for future vaccine research.
Physical activity in leisure-time and risk of cancer: 14-year follow-up of 28,000 Danish men and women
Authors: Schnohr Peter , Grønbæk Morten , Petersen Liselotte , Ole Hein Hans , Ia Sørensen Thorkild
Published: February 2005

Aim: The preventive effect of physical activity on risk of cancer in general remains controversial. This study aimed at assessment of the associations between leisure- time physical activity and incidence of cancer in the general population of adult men and women. Methods: 13,216 women and 18,718 men aged 20—93 years selected from the general population participated in a health examination including a questionnaire with information on physical activity, smoking, alcohol intake, postmenopausal hormones, and socioeconomic status. Incident cases of cancers where recorded during a follow-up period of 14 years. The six most frequent cancer cases in both sexes were included in this analysis. Results: A highly significant inverse association was seen between vigorous physical activity in leisure time and cancer of the ovary, adjusted rate ratio being 0.33 (95% CI 0.16—0.67; p=0.001) for the most physical active women. In men there was a highly significant increase for non-melanoma skin cancer, with adjusted rate ratio of 1.72 (95% CI 1.23—2.40; p=0.001), for the most active men and vigorous activity was associated with a non-significant lower risk of colon cancer, the adjusted rate ratio being 0.72 (95% CI 0.47—1.11; p=0.06). Conclusion: Generally, there were no, or only weakly, inverse associations between physical activity in leisure time and incidence of cancer, except for cancer of the ovary.
Implementation of functional assessment scales in geriatric practice: A feasibility study
Authors: Poulsen Ingrid , Hesselbo Bjørn , Pietersen Inge , Schroll Marianne
Published: February 2005

Aim: A study was undertaken to evaluate the feasibility of functional assessment scales regarding completion rate and ability to document functional changes in geriatric rehabilitation patients. Methods: Five functional assessment scales were implemented, and used on admission and discharge as part of standard care. Results: Of 2,812 patients, 90 patients (3.2%) had no scales administered, 2,330 patients (82.9%) had between one and six scales administered and 392 (13.9%) had a complete data set (seven scales). The percentage of inpatients who were independent or almost independent in basic ADL functions improved from 30% to 60% during hospitalization; 53% had cognitive impairment, while 19% expressed depressive thoughts or depression on admission. Conclusion: Functional assessment scales were feasible in the clinical routine, gave important information on patients' functional status at baseline, and showed that patients improved their physical function considerably during hospitalization. Interdisciplinary teamwork and management affect the success of the implementation of assessment scales.
Normal modes for predicting protein motions: A comprehensive database assessment and associated Web tool
Authors: Alexandrov Vadim , Lehnert Ursula , Echols Nathaniel , Milburn Duncan , Engelman Donald , Gerstein Mark
Published: February 2005

We carry out an extensive statistical study of the applicability of normal modes to the prediction of mobile regions in proteins. In particular, we assess the degree to which the observed motions found in a comprehensive data set of 377 nonredundant motions can be modeled by a single normal‐mode vibration. We describe each motion in our data set by vectors connecting corresponding atoms in two crystallographically known conformations. We then measure the geometric overlap of these motion vectors with the displacement vectors of the lowest‐frequency mode, for one of the conformations. Our study suggests that the lowest mode contains useful information about the parts of a protein that move most (i.e., have the largest amplitudes) and about the direction of this movement. Based on our findings, we developed a Web tool for motion prediction (available from http://molmovdb.org/nma) and apply it here to four representative motions—from bacteriorhodopsin, calmodulin, insulin, and T7 RNA polymerase.