bluuebunny/crossref_metadata_2025 huggingface dataset:
Polyunsaturated fatty acids modulate NOX 4 anion superoxide production in human fibroblasts
Authors: Rossary Adrien , Arab Khelifa , Steghens Jean-Paul
Published: November 2007

The strong ROS (reactive oxygen species) production, part of an antioxidant response of human fibroblasts triggered by DHA (docosahexaenoic acid; C22:6,n−3), served as a model for deciphering the relative contribution of NOX (NADPH oxidase) to ROS production, as the role of this enzymatic system remains controversial. Using hydroxyethidium fluorescence for fibroblast ROS production, RT (reverse transcriptase)–PCR for NOX 4 mRNA quantification and mRNA silencing, we show that ROS production evolves in parallel with the catalytic activity of NOX and is suppressed by siNOX 4 (small interference oligonucleotide RNA directed against NOX 4) silencing. Apocynin and plumbagin, specific inhibitors of NOX, prevent ROS production in this cellular model and confirm the role of NOX 4 for this production. Furthermore, we show that, in cell lysates, NOX 4 activity can be modulated by PUFAs (polyunsaturated fatty acids) at the micromolar level in the presence of calcium: NOX 4 activity is increased by arachidonic acid (C20:4,n−6) (∼175% of the control), and conjugated linoleic acid (C18:2 [9Z,11E]) is a potent inhibitor (50% of the control). Unexpectedly, intracellular superoxide dismutase does not participate in the modulation of this ROS production and the opposite effects of some PUFAs, described in our experiments, could suggest another way of regulating NOX activity.
Naturally occurring and bioengineered apoA-I mutations that inhibit the conversion of discoidal to spherical HDL: the abnormal HDL phenotypes can be corrected by treatment with LCAT
Authors: Koukos Georgios , Chroni Angeliki , Duka Adelina , Kardassis Dimitris , Zannis Vassilis I.
Published: November 2007

In the present study we have used adenovirus-mediated gene transfer of apoA-I (apolipoprotein A-I) mutants in apoA-I−/− mice to investigate how structural mutations in apoA-I affect the biogenesis and the plasma levels of HDL (high-density lipoprotein). The natural mutants apoA-I(R151C)Paris, apoA-I(R160L)Oslo and the bioengineered mutant apoA-I(R149A) were secreted efficiently from cells in culture. Their capacity to activate LCAT (lecithin:cholesterol acyltransferase) in vitro was greatly reduced, and their ability to promote ABCA1 (ATP-binding cassette transporter A1)-mediated cholesterol efflux was similar to that of WT (wild-type) apoA-I. Gene transfer of the three mutants in apoA-I−/− mice generated aberrant HDL phenotypes. The total plasma cholesterol of mice expressing the apoA-I(R160L)Oslo, apoA-I(R149A) and apoA-I(R151C)Paris mutants was reduced by 78, 59 and 61% and the apoA-I levels were reduced by 68, 64 and 55% respectively, as compared with mice expressing the WT apoA-I. The CE (cholesteryl ester)/TC (total cholesterol) ratio of HDL was decreased and the apoA-I was distributed in the HDL3 region. apoA-I(R160L)Oslo and apoA-I(R149A) promoted the formation of preβ1 and α4-HDL subpopulations and gave a mixture of discoidal and spherical particles. apoA-I(R151C)Paris generated subpopulations of different sizes that migrate between preβ and α-HDL and formed mostly spherical and a few discoidal particles. Simultaneous treatment of mice with adenovirus expressing any of the three mutants and human LCAT normalized plasma apoA-I, HDL cholesterol levels and the CE/TC ratio. It also led to the formation of spherical HDL particles consisting mostly of α-HDL subpopulations of larger size. The correction of the aberrant HDL phenotypes by treatment with LCAT suggests a potential therapeutic intervention for HDL abnormalities that result from specific mutations in apoA-I.
The chondroitin sulfate form of invariant chain trimerizes with conventional invariant chain and these complexes are rapidly transported from thetrans-Golgi network to the cell surface
Authors: Arneson Lynne S. , Miller Jim
Published: November 2007

Targeting of MHCII–invariant chain complexes from the trans-Golgi network to endosomes is mediated by two di-leucine-based signals present in the cytosolic domain of invariant chain. Generation of this endosomal targeting signal is also dependent on multimerization of the invariant chain cytosolic domain sequences, mediated through assembly of invariant chain into homotrimers. A small subset of invariant chain is modified by the addition of chondroitin sulfate and is expressed on the cell surface in association with MHCII. In the present study, we have followed the biosynthetic pathway and route of intracellular transport of this proteoglycan form of invariant chain. We found that the efficiency of chondroitin sulfate modification can be increased by altering the invariant chain amino acid sequence around Ser-201 to the xylosylation consensus sequence. Our results also indicate that, following sulfation, the proteoglycan form is transported rapidly from the trans-Golgi network to the cell surface and is degraded following internalization into an endocytic compartment. Invariant chain–chondroitin sulfate is present in invariant chain trimers that also include conventional non-proteoglycan forms of invariant chain. These data indicate that invariant chain–chondroitin sulfate-containing complexes are transported rapidly from the trans-Golgi network to the cell surface in spite of the presence of an intact endosomal localization signal. Furthermore, these results suggest that invariant chain–chondroitin sulfate may play an important role in the generation of cell-surface pools of invariant chain that can serve as receptors for CD44 and macrophage migration inhibitory factor.
Effect of hypothermia and HTK on the microcirculation in the rat cremaster muscle after ischaemia
Authors: BASTIAANSE Jacqueline , SLAAF Dick W. , oude EGBRINK Mirjam G. A. , ANDERSON Gary L. , VINK Hans , van der HEIJDEN Brigitte E. P. A. , KON Moshe
Published: November 2007

Hypothermia is an important preservation method for tissues and solid organs. The aim of the present study was to assess in rat cremaster muscle the effect of hypothermia, without or with pre-ischaemic HTK (histidine-tryptophan-ketoglutarate–Bretschneider solution) perfusion, on microvascular consequences of 4 or 6 h ischaemia and 2 h of reperfusion. Intravital microscopy was applied to examine capillary perfusion and leucocyte–endothelium interactions. The cremaster muscle was subjected to 4 or 6 h of cold (4 °C) or warm (33–34 °C) ischaemia and 2 h of reperfusion. Measurements were performed at baseline, prior to HTK perfusion and ischaemia, and at 0, 1 and 2 h after blood flow restoration. Hypothermia completely prevented the 50% reduction in capillary perfusion that was observed previously at start of reperfusion after 4 h warm ischaemia. After 6 h of warm ischaemia, perfusion resumed in only 45% of capillaries and remained at this low level during reperfusion. In contrast, only a slight decrease (<10%) in capillary perfusion was observed after 6 h of cold ischaemia. Pre-ischaemic HTK perfusion had no beneficial effect on tissue perfusion. Both hypothermia and HTK attenuated the significant increase in venular leucocyte–vessel wall interactions, which was observed after 4 h of warm ischaemia in a previous study. Combined application of both interventions had no additional effects. After 6 h of warm ischaemia, no increase in leucocyte–vessel wall interactions was observed, possibly due to venular flow reduction. In conclusion, hypothermia preserves capillary perfusion and prevents an increase in leucocyte–vessel wall interactions during reperfusion after muscle tissue ischaemia. Preischaemic perfusion of the vasculature with HTK does not improve the effects of cold storage on tissue perfusion, but attenuates the inflammatory response independently of temperature effect.
Plasma vascular endothelial growth factor as a marker for early vascular damage in hypertension
Authors: TSAI Wei-Chuan , LI Yi-Heng , HUANG Yao-Yi , LIN Chin-Chan , CHAO Ting-Hsing , CHEN Jyh-Hong
Published: November 2007

Elevation of plasma VEGF (vascular endothelial growth factor) has been noted in patients with hypertension or atherosclerosis. VEGF has been regarded as a marker for endothelial dysfunction. However, the role of VEGF in hypertension-induced vascular injury and its relationship with endothelial function have not been studied. This study included 20 untreated hypertensive men with grade 1 or 2 hypertensive retinopathy, 10 untreated hypertensive men without hypertensive retinopathy and 10 healthy controls. None of the hypertensive patients had diabetes, renal impairment or overt vascular diseases. Plasma VEGF and adhesion molecules were measured using ELISAs. Endothelial function was measured by FMD (flow-mediated vasodilation) of the brachial artery. Plasma levels of VEGF, excluding adhesion molecules, were significantly higher in hypertensive patients with retinopathy when compared with patients without retinopathy (152.4±80.8 pg/ml versus 104.7±27.2 pg/ml, P=0.035) or controls (152.4±80.8 pg/ml versus 98.9±23.7 pg/ml, P=0.025). Levels of FMD were significantly lower in hypertensive patients than controls, but there were no significant differences between patients with or without retinopathy. Degrees of FMD were inversely correlated with VEGF levels (r=−0.351, P=0.031). Elevation of plasma VEGF was associated with hypertensive retinopathy. Plasma VEGF could be used as a marker of early vascular damage induced by hypertension.
Effect of coffee on endothelial function in healthy subjects: the role of caffeine
Authors: PAPAMICHAEL Chris M. , AZNAOURIDIS Konstantinos A. , KARATZIS Emmanouil N. , KARATZI Kalliopi N. , STAMATELOPOULOS Kimon S. , VAMVAKOU Georgia , LEKAKIS John P. , MAVRIKAKIS Myron E.
Published: November 2007

Coffee is one of the most widely used pharmacologically active beverages. The present study was designed to evaluate the acute effect of coffee ingestion on endothelial function in healthy individuals, and the potential role of caffeine. We studied 17 healthy young adults (28.9±3.0 years old; nine men), who were regular non-heavy coffee drinkers. The endothelial performance was estimated by endothelium-dependent FMD (flow-mediated dilatation) of the brachial artery before and 30, 60, 90 and 120 min after ingestion of a cup of caffeinated coffee (80 mg of caffeine) or the corresponding decaffeinated beverage (<2 mg of caffeine) in two separate sessions, following a randomized single-blind cross-over design. There was no difference in baseline FMD values between the two sessions [7.78 compared with 7.07% after caffeinated and decaffeinated coffee respectively; P=NS (not significant)]. Caffeinated coffee led to a decline of FMD (7.78, 2.86, 2.12, 4.44 and 4.57% at baseline, 30, 60, 90 and 120 min respectively; P<0.001). This adverse effect was focused at 30 (P=0.004) and 60 min (P<0.001). No significant effect on FMD was found with the decaffeinated coffee session (7.07, 6.24, 5.21, 7.41 and 5.20%; P=NS). The composite effect of the type of coffee consumed over time on FMD was significantly different (P=0.021). In conclusion, coffee exerts an acute unfavourable effect on the endothelial function in healthy adults, lasting for at least 1 h after intake. This effect might be attributed to caffeine, given that decaffeinated coffee was not associated with any change in the endothelial performance.
Fetal and perinatal programming of appetite
Authors: CRIPPS Roselle L. , MARTIN-GRONERT Malgorzata S. , OZANNE Susan E.
Published: November 2007

There is increasing concern about the rapidly rising incidence of obesity worldwide and its impact both on mortality, morbidity and the cost of healthcare. In the last 15 years, a large volume of research has linked low birth weight to many adult diseases in humans, such as Type II diabetes, cardiovascular disease, hypertension and the metabolic syndrome. Obesity is a causal factor in all these conditions. There are epidemiological studies linking low birth weight to increased adiposity, but the timing of the insult during gestation seems crucial, as reducing maternal nutrition in late gestation and during lactation causes a reduction in later obesity. Recent studies in animal models have provided clues towards mechanisms of altered appetite regulation following alterations in fetal and neonatal growth. The outcome of these and future studies could prove clinically crucial, particularly in the debate over the benefits of breast feeding, which provides a lower plane of nutrition compared with formula feeding.
Effect of parathyroid-hormone-related protein on human platelet activation
Authors: Ortega Arantxa , Pérez de Prada Ma Teresa , Mateos-Cáceres Petra J. , Ramos Mozo Priscila , González-Armengol Juan J. , González del Castillo Juan M. , Martín Sánchez Javier , Villarroel Pedro , Santiago José L. , Bosch Ricardo J. , Macaya Carlos , Esbrit Pedro , López-Farré Antonio J.
Published: November 2007

Evidence suggests that PTHrP [PTH (parathyroid hormone)-related protein] can act as an inflammatory mediator in several pathological settings including cardiovascular disease. The aim of the present study was to determine whether PTHrP might be involved in human platelet activation. We used a turbidimetric method to determine platelet aggregation. The expression of PTH1R (PTH type 1 receptor) in human platelets was analysed by Western blot and flow cytometry analyses. PTHrP-(1–36) (10−7 mol/l) by itself failed to modify the activation of platelets. However, it significantly enhanced ADP-induced platelet activation, and also increased the ability of other agonists (thrombin, collagen and arachidonic acid) to induce platelet aggregation. H89 (10−6 mol/l) and 25×10−6 mol/l Rp-cAMPS (adenosine 3′,5′-cyclic monophosphorothioate Rp-isomer), two protein kinase A inhibitors, and 25×10−9 mol/l bisindolylmaleimide I, a protein kinase C inhibitor, partially decreased the enhancing effect of PTHrP-(1–36) on ADP-induced platelet activation. Meanwhile, 10−6 mol/l PTHrP-(7–34), a PTH1R antagonist, as well as 10−5 mol/l PD098059, a MAPK (mitogen-activated protein kinase) inhibitor, or a farnesyltransferase inhibitor abolished this effect of PTHrP-(1–36). Moreover, 10−7 mol/l PTHrP-(1–36) increased (2-fold over control) MAPK activation in human platelets. PTH1R was detected in platelets, and the number of platelets expressing it on their surface in patients during AMI (acute myocardial infarction) was not different from that in a group of patients with similar cardiovascular risk factors without AMI. Western blot analysis showed that total PTH1R protein levels were markedly higher in platelets from control than those from AMI patients. PTH1R was found in plasma, where its levels were increased in AMI patients compared with controls. In conclusion, human platelets express the PTH1R. PTHrP can interact with this receptor to enhance human platelet activation induced by several agonists through a MAPK-dependent mechanism.
Knee replacement surgery as a human clinical model of the effects of ischaemia/reperfusion upon skeletal muscle
Authors: Westman Bo , Weidenhielm Lars , Rooyackers Olav , Fredriksson Katarina , Wernerman Jan , Hammarqvist Folke
Published: November 2007

The temporal pattern of metabolic alterations in muscle tissue during total ischaemia and reperfusion are not well-characterized in humans with respect to glutathione, amino acids and energy-rich compounds. In the present study, knee replacement surgery was used as a clinical model to elucidate this pattern of metabolic alterations. Patients (n=15) undergoing elective knee replacement surgery employing tourniquet ischaemia were studied. Muscle biopsies were taken from the quadriceps femoris muscle on the operated side preoperatively, at maximal ischaemia and after 24 h of reperfusion. The biopsies were analysed for glutathione, amino acids and energy-rich compounds. In addition the patients were randomized to receive either glucose or a mannitol infusion in the 24 h following tourniquet ischaemia. During ischaemia, muscle lactate increased by 400% (P<0.05) and phosphocreatine decreased by 70% (P<0.05). During the subsequent 24 h of reperfusion, muscle-reduced glutathione and total glutathione decreased by 27% and 22% (P<0.05) respectively. The muscle amino acid pattern changed during ischaemia with an increase in alanine by 65% (P<0.001) and a decrease in glutamate by 29% (P<0.001). During the reperfusion part of the study, no differences attributable to the infusion of mannitol or glucose were observed. During tourniquet ischaemia and subsequent reperfusion, changes in glutathione metabolism developed, indicating oxidative stress. Knee replacement surgery as a clinical model was useful during the ischaemia period, whereas the reperfusion period was dominated by the general changes seen postoperatively.
Generalization of the Förster resonance energy transfer theory for quantum mechanical modulation of the donor-acceptor coupling
Authors: Jang Seogjoo
Published: November 2007

The Förster resonance energy transfer theory is generalized for inelastic situations with quantum mechanical modulation of the donor-acceptor coupling. Under the assumption that the modulations are independent of the electronic excitation of the donor and the acceptor, a general rate expression is derived, which involves two dimensional frequency-domain convolution of the donor emission line shape, the acceptor absorption line shape, and the spectral density of the modulation of the donor-acceptor coupling. For two models of modulation, detailed rate expressions are derived. The first model is the fluctuation of the donor-acceptor distance, approximated as a quantum harmonic oscillator coupled to a bath of other quantum harmonic oscillators. The distance fluctuation results in additional terms in the rate, which in the small fluctuation limit depend on the inverse eighth power of the donor-acceptor distance. The second model is the fluctuation of the torsional angle between the two transition dipoles, which is modeled as a quantum harmonic oscillator coupled to a bath of quantum harmonic oscillators and causes sinusoidal modulation of the donor-acceptor coupling. The rate expression has new elastic and inelastic terms, depending sensitively on the value of the minimum energy torsional angle. Experimental implications of the present theory and some of the open theoretical issues are discussed.
Mathematical and physical aspects of Kappa velocity distribution
Authors: Hau L.-N. , Fu W.-Z.
Published: November 2007

One major characteristic associated with collisionless space plasmas is the development of non-Maxwellian velocity distribution that in many circumstances can be represented by the κ function characterized by the κ parameter. This paper discusses the mathematical character and physical origin of the κ function by first showing that the κ velocity function may be expressed in terms of exponential functions multiplied by the kinetic energy and its higher orders. The possible development of κ velocity distribution is illustrated by the problem of low-frequency waves and instabilities in uniform magnetized plasmas with bi-Maxwellian distribution. It is observed that the background and perturbed distribution functions bear the same forms as the zeroth- and higher-order terms of the κ function expanded in the limit of κ→∞. The consequence of assuming κ velocity distribution in inhomogeneous plasmas is illustrated by the Vlasov-Maxwell equilibrium problems that show the nonthermal equilibrium characteristic of nonuniform plasmas. A generalized Grad-Shafranov equation is proposed for two-dimensional Vlasov equilibria with κ velocity distribution.
Investigations on the structure of dimethyl sulfoxide and acetone in aqueous solution
Authors: McLain Sylvia E. , Soper Alan K. , Luzar Alenka
Published: November 2007

Aqueous solutions of dimethyl sulfoxide (DMSO) and acetone have been investigated using neutron diffraction augmented with isotopic substitution and empirical potential structure refinement computer simulations. Each solute has been measured at two concentrations—1:20 and 1:2 solute:water mole ratios. At both concentrations for each solute, the tetrahedral hydrogen bonding network of water is largely unperturbed, though the total water molecule coordination number is reduced in the higher 1:2 concentrations. With higher concentrations of acetone, water tends to segregate into clusters, while in higher concentrations of DMSO the present study reconfirms that the structure of the liquid is dominated by DMSO-water interactions. This result may have implications for the highly nonideal behavior observed in the thermodynamic functions for 1:2 DMSO-water solutions.
Calculation of surface tension via area sampling
Authors: Errington Jeffrey R. , Kofke David A.
Published: November 2007

We examine the performance of several molecular simulation techniques aimed at evaluation of the surface tension through its thermodynamic definition. For all methods explored, the surface tension is calculated by approximating the change in Helmholtz free energy associated with a change in interfacial area through simulation of a liquid slab at constant particle number, volume, and temperature. The methods explored fall within three general classes: free-energy perturbation, the Bennett acceptance-ratio scheme, and the expanded ensemble technique. Calculations are performed for both the truncated Lennard-Jones and square-well fluids at select temperatures spaced along their respective liquid-vapor saturation lines. Overall, we find that Bennett and expanded ensemble approaches provide the best combination of accuracy and precision. All of the methods, when applied using sufficiently small area perturbation, generate equivalent results for the Lennard-Jones fluid. However, single-stage free-energy-perturbation methods and the closely related test-area technique recently introduced by Gloor et al. [J. Chem. Phys. 123, 134703 (2005)] generate surface tension values for the square-well fluid that are not consistent with those obtained from the more robust expanded ensemble and Bennett approaches, regardless of the size of the area perturbation. Single-stage perturbation methods fail also for the Lennard-Jones system when applied using large area perturbations. Here an analysis of phase-space overlap produces a quantitative explanation of the observed inaccuracy and shows that the satisfactory results obtained in these cases from the test-area method arise from a cancellation of errors that cannot be expected in general. We also briefly analyze the variation in method performance with respect to the adjustable parameters inherent to the techniques.
Photoelectron spectroscopy of adiabatically bound valence anions of rare tautomers of the nucleic acid bases
Authors: Li Xiang , Bowen Kit H. , Haranczyk Maciej , Bachorz Rafał A. , Mazurkiewicz Kamil , Rak Janusz , Gutowski Maciej
Published: November 2007

Anionic states of nucleic acid bases (NABs) are involved in DNA damage by low-energy electrons and in charge transfer through DNA. Previous gas phase studies of free, unsolvated NAB parent anions probed mostly dipole-bound states, which are not present in condensed phase environments. Recently, we demonstrated that very rare tautomers of uracil (U), cytosine (C), adenine (A), and guanine (G), which are obtained from canonical tautomers through N-to-C proton transfers, support valence anionic states. Here we report the photoelectron spectrum of the final member of the NABs series: the valence state of the thymine (T) anion. Additionally, we summarized the work of all five NABs. All of the newfound anionic tautomers of the NABs may be formed via dissociative electron attachment followed by hydrogen atom reattachment to a carbon atom. Furthermore, these unusual tautomers may affect the structure and properties of DNA and RNA exposed to low-energy electrons. The new valence states observed here, unlike dipole bound states, could exist in condensed phases and may be relevant to radiobiological damage.
Enhanced light extraction from GaN-based green light-emitting diode with photonic crystal
Authors: Kim Ja-Yeon , Kwon Min-Ki , Lee Ki-Sung , Park Seong-Ju , Kim Sang Hoon , Lee Ki-Dong
Published: October 2007

This letter reports the properties of GaN-based green light-emitting diodes (LEDs) having a p-GaN photonic crystal layer with a photonic bandgap (PCWG) and without a photonic bandgap (PCOG). With decreasing the photoluminescence (PL) detection angle from 140° to 60°, the enhancement of PL intensity of LED with PCWG was largely increased from 9 to 25 times, compared to that of LEDs without a patterned structure, while the PL intensity of LED with PCOG was increased from 4.6 to 5.6 times. The electroluminescence output power of green LEDs with a PCWG was enhanced about two times compared to LEDs with a PCOG. These results suggest that the light extraction of green LEDs can be greatly increased by using PCWG instead of PCOG.
An anomalous subdiffusion model for calcium spark in cardiac myocytes
Authors: Tan Wenchang , Fu Chaoqi , Fu Ceji , Xie Wenjun , Cheng Heping
Published: October 2007

The elementary events of excitation-contraction coupling in heart muscle are Ca2+ sparks, which arise from ryanodine receptors in the sarcoplasmic reticulum (SR). Here, an anomalous subdiffusion model is developed to explore Ca2+ spark formation in cardiac myocytes. Numerical simulations reproduce the brightness, the time course, and spatial size of a typical cardiac Ca2+ spark. It is suggested that the diffusion of Ca2+ spark in the cytoplasm may no longer obey Fickian second law, but the anomalous space subdiffusion. The physical reason is perhaps due to the effects of the electric field of the calcium ions and the viscoelasticity of the cytoplasm and its complex structures.
1.54
μ
m
photoluminescence emission and oxygen vacancy as sensitizer in Er-doped HfO2 films
Authors: Wang Junzhuan , Xia Yan , Shi Yi , Shi Zhuoqiong , Pu Lin , Zhang Rong , Zheng Youdou , Tao Zhensheng , Lu Fang
Published: November 2007

In this letter, we report on the characteristics of 1.54μm photoluminescence emission of Er-doped HfO2 films synthesized by pulsed laser deposition and ion implantation. An efficient emission at 1.54μm in the annealed HfO2 films has been observed under a broad band excitation from 400nm to a higher energy at room temperature. X-ray diffraction and electron paramagnetic resonant measurements were used to analyze the correlation between the optical properties and microstructures. An energy transfer mechanism is proposed that the O vacancy in the bulk acts as an effective sensitizer for the neighboring Er ions and greatly enhances the 1.54μm band emission. These results lay an important basis for the future silicon-based integrated optoelectronic device applications of Er-doped HfO2 films.
The improvement of retention time of metal-ferroelectric (PbZr0.53Ti0.47O3)-insulator (ZrO2)-semiconductor transistors and capacitors by leakage current reduction using surface treatment
Authors: Shih Wen-Chieh , Kang Kun-Yung , Lee Joseph Ya-Min
Published: November 2007

Metal-ferroelectric-insulator-semiconductor transistors (MFISFETs) and capacitors with the structure of Al∕Pb (Zr0.53,Ti0.47) O3∕ZrO2∕Si were fabricated. The wafers were pretreated with H2O2 before ZrO2 deposition and/or post-treated with HCl after ZrO2 deposition. The leakage current density at 5V is reduced from 10−1to5×10−6A∕cm2. The subthreshold slope was improved to 91mV/decade. The MFISFETs maintain a threshold voltage window of about 1.1V after an elapsed time of 3000s. The mobility is 267cm2∕Vs. The improvements are most likely due to the reduction of interfacial layer thickness and the interface states at the ZrO2∕Si interface.
Dielectric tunability of Ba0.6Sr0.4TiO3/poly(methyl methocrylate) composites in 1-3-type structure
Authors: Xiang Feng , Wang Hong , Li Kecheng , Chen Yuehua , Zhang Minghui , Shen Ziyuan , Yao Xi
Published: November 2007

The Ba0.6Sr0.4TiO3 (BST)/poly(methyl methacrylate) (PMMA) tunable composites in 1-3-type structure consisting of BST rods in low-permittivity PMMA matrix are fabricated by dice and fill technique. For the composite containing 41.6vol% BST, the permittivity and the loss tangent of the composite are 1212 and 0.026 at 10kHz, respectively, while the dielectric tunability is about 36% under the 16kV∕cm dc bias flied. The theoretical tunability and permittivity are in agreement with the experimental data. The 1-3-type BST/PMMA composites can meet the device requirement for tunable dielectrics with high dielectric tunability and low permittivity.
The Politics of Community-Based Conservation in Natural Resource Management: A Focus for International Comparative Analysis
Authors: Selfa Theresa , Endter-Wada Joanna
Published: November 2007

The promotion of increased community participation in natural resource management and conservation by international and state natural resource agencies rests on the assumption that local communities that have connections to, knowledge about, and interests in proximate resources should participate in the management of those resources. By using a political ecology approach, three case studies of natural resource management are analyzed which span industrialized and developing world contexts—agro-ecological zoning in the western Amazon, a social forestry project in the southern Philippines, and a forest plan revision process in southern Utah. We suggest the need for more attention to how communities are defined and how participation is formalized by institutions, as well as to contested meanings of conservation. We find that, despite espousing agendas of community-based conservation, international and state agencies retain authority over key decisions about natural resource management, use, and allocation.
Geographical review of the ostracod genus Vestalenula (Darwinulidae) and a new subterranean species from southern France
Authors: Artheau Malvina
Published: November 2007

A new species of Vestalenula is described. Vestalenula carveli, sp. nov. was found in the interstitial habitat of rivers during the PASCALIS European program when sampling three sites on the Aude River and Tech River basins (Roussillon region, southern France). With its large caudal brooding cavity, the presence of an external keel on the right valve and an internal tooth on the left valve, V. carveli is a typical representative of the genus. This new record brings the worldwide number of Vestalenula species to 24. Vestalenula representatives are known from the Lower Miocene to the present. A review of present-day knowledge of the geographical distribution of the genus and a cladistic analysis are presented in order to assess the biogeography of this genus and the importance of the discovery of a new subterranean species in southern France. The geographical review of the genus showed that most species of Vestalenula occur in subtropical regions. However, V. cylindrica, V. boteai and V. danielopoli lived, or are living, in the Palearctic. Vestalenula pagliolii occurs in both hemispheres. Many of the Recent species live in semiterrestrial and/or interstitial habitats and occur in geographically restricted areas. The distribution of the species of Vestalenula suggests independent colonisation of the subterranean environment by several species; this hypothesis is supported by the cladistic analysis.
Conifer ovulate cones accumulate pollen principally by simple impaction
Authors: Cresswell James E. , Henning Kevin , Pennel Christophe , Lahoubi Mohamed , Patrick Michael A. , Young Phillipe G. , Tabor Gavin R.
Published: November 2007

In many pine species (Family Pinaceae), ovulate cones structurally resemble a turbine, which has been widely interpreted as an adaptation for improving pollination by producing complex aerodynamic effects. We tested the turbine interpretation by quantifying patterns of pollen accumulation on ovulate cones in a wind tunnel and by using simulation models based on computational fluid dynamics. We used computer-aided design and computed tomography to create computational fluid dynamics model cones. We studied three species:
Pinus radiata
,
Pinus sylvestris
, and
Cedrus libani
. Irrespective of the approach or species studied, we found no evidence that turbine-like aerodynamics made a significant contribution to pollen accumulation, which instead occurred primarily by simple impaction. Consequently, we suggest alternative adaptive interpretations for the structure of ovulate cones.
Coupling of protein and hydration-water dynamics in biological membranes
Authors: Wood K. , Plazanet M. , Gabel F. , Kessler B. , Oesterhelt D. , Tobias D. J. , Zaccai G. , Weik M.
Published: November 2007

The dynamical coupling between proteins and their hydration water is important for the understanding of macromolecular function in a cellular context. In the case of membrane proteins, the environment is heterogeneous, composed of lipids and hydration water, and the dynamical coupling might be more complex than in the case of the extensively studied soluble proteins. Here, we examine the dynamical coupling between a biological membrane, the purple membrane (PM), and its hydration water by a combination of elastic incoherent neutron scattering, specific deuteration, and molecular dynamics simulations. Examining completely deuterated PM, hydrated in H
2
O, allowed the direct experimental exploration of water dynamics. The study of natural abundance PM in D
2
O focused on membrane dynamics. The temperature-dependence of atomic mean-square displacements shows inflections at 120 K and 260 K for the membrane and at 200 K and 260 K for the hydration water. Because transition temperatures are different for PM and hydration water, we conclude that ps–ns hydration water dynamics are not directly coupled to membrane motions on the same time scale at temperatures <260 K. Molecular-dynamics simulations of hydrated PM in the temperature range from 100 to 296 K revealed an onset of hydration-water translational diffusion at ≈200 K, but no transition in the PM at the same temperature. Our results suggest that, in contrast to soluble proteins, the dynamics of the membrane protein is not controlled by that of hydration water at temperatures <260 K. Lipid dynamics may have a stronger impact on membrane protein dynamics than hydration water.
Higher blood flow and circulating NO products offset high-altitude hypoxia among Tibetans
Authors: Erzurum S. C. , Ghosh S. , Janocha A. J. , Xu W. , Bauer S. , Bryan N. S. , Tejero J. , Hemann C. , Hille R. , Stuehr D. J. , Feelisch M. , Beall C. M.
Published: October 2007

The low barometric pressure at high altitude causes lower arterial oxygen content among Tibetan highlanders, who maintain normal levels of oxygen use as indicated by basal and maximal oxygen consumption levels that are consistent with sea level predictions. This study tested the hypothesis that Tibetans resident at 4,200 m offset physiological hypoxia and achieve normal oxygen delivery by means of higher blood flow enabled by higher levels of bioactive forms of NO, the main endothelial factor regulating blood flow and vascular resistance. The natural experimental study design compared Tibetans at 4,200 m and U.S. residents at 206 m. Eighty-eight Tibetan and 50 U.S. resident volunteers (18–56 years of age, healthy, nonsmoking, nonhypertensive, not pregnant, with normal pulmonary function) participated. Forearm blood flow, an indicator of systemic blood flow, was measured noninvasively by using plethysmography at rest, after breathing supplemental oxygen, and after exercise. The Tibetans had more than double the forearm blood flow of low-altitude residents, resulting in greater than sea level oxygen delivery to tissues. In comparison to sea level controls, Tibetans had >10-fold-higher circulating concentrations of bioactive NO products, including plasma and red blood cell nitrate and nitroso proteins and plasma nitrite, but lower concentrations of iron nitrosyl complexes (HbFe
II
NO) in red blood cells. This suggests that NO production is increased and that metabolic pathways controlling formation of NO products are regulated differently among Tibetans. These findings shift attention from the traditional focus on pulmonary and hematological systems to vascular factors contributing to adaptation to high-altitude hypoxia.
Research of Natural Frequency of Single-walled Carbon Nanotube
Authors: Lu Ji-nan , Chen Hai-bo , Lu Pin , Zhang Pei-qiang
Published: November 2007

The modified molecular structural mechanics method (MMSMM) is extended to analyze the dynamic characteristics of single-walled carbon nanotubes (SWCNTs). In MMSMM, the deformation potential of SWCNT is decomposed and it can be easily expressed as the function of the positions of carbon atoms in molecular mechanics, and so the stiffness matrix of SWCNT can be obtained. The elemental mass matrix is a diagonal one, so the natural frequency and vibration mode of SWCNT can be calculated effectively. In this work, the form of cantilevered nanotubes is analyzed. The natural frequencies of SWCNT computed by this algorithm are discussed. The frequency dependence on the tube diameter and length of SWCNT is confirmed and, it is shown that when the diameter of tube is small the frequency can reach the the GHz level. The frequency results and the vibration modes are comparable with those of other researchers. Furthermore, a new FEM continuum-model is proposed to analyze the dynamic character of SWCNT to compare with these results by MMSMM.
Comparative Study of CuO Species on CuO/Al2O3, CuO/CeO2-Al2O3 and CuO/La2O-Al2O3 Catalysts for CO Oxidation
Authors: Jin Ling-yun , He Mai , Lu Ji-qing , Luo Meng-fei , Fang Ping , Xie Yun-long
Published: November 2007

CuO/Al2O3, CuO/CeO2-Al2O3, and CuO/La2O3-Al2O3 (denoted as Cu/Al, Cu/CeAl, and Cu/LaAl) catalysts were prepared by an impregnation method. CuO species and CuO/Al2O3 thermal solid-solid interaction were characterized by in situ XRD, Raman spectroscopy and H2-TPR techniques. For the Cu/Al catalyst, a CuAl2O4 phase exists between the CuO and Al2O3 layer and the CuO phase exists on the surface in both highly dispersed and bulk forms. For the Cu/CeAl catalyst, there is highly dispersed and bulk CuO on the surface, but most of the CuO has transferred into the internal layer of CeO2 as bulk CuO and CuAl2O4. For the Cu/LaAl catalyst, only bulk CuO is present on the surface of the catalyst and no CuAl2O4 is formed. The catalytic activity order for CO oxidation is Cu/CeAl>Cu/Al>Cu/LaAl. The highly dispersed CuO on the catalyst surface may be the active phase for CO oxidation. The results show that the addition of CeO2 not only promotes both the transference of CuO and the formation of CuAl2O4 but also favors the CO oxidation due to the association of highly dispersed CuO with CeO2, while La2O3 hinders the transference of CuO and the formation of CuAl2O4.
Functional diversification within and between muscle synergists during locomotion
Authors: Higham Timothy E , Biewener Andrew A , Wakeling James M
Published: November 2007

Locomotion arises from the complex and coordinated function of limb muscles. Yet muscle function is dynamic over the course of a single stride and between strides for animals moving at different speeds or on variable terrain. While it is clear that motor unit recruitment can vary between and within muscles, we know little about how work is distributed within and between muscles underin vivoconditions. Here we show that the lateral gastrocnemius (LG) of helmeted guinea fowl (Numida meleagris) performs considerably more work than its synergist, the medial gastrocnemius (MG) and that the proximal region of the MG (pMG) performs more work than the distal region (dMG). Positive work done by the LG was approximately twice that of the proximal MG when the birds walked at 0.5 m s−1, and four times when running at 2.0 m s−1. This is probably due to different moments at the knee, as well as differences in motor unit recruitment. The dMG performed less work than the pMG because its apparent dynamic stiffness was greater, and because it exhibited a greater recruitment of slow-twitch fibres. The greater compliance of the pMG leads to increased stretch of its fascicles at the onset of force, further enhancing force production. Our results demonstrate the capacity for functional diversity between and within muscle synergists, which increases with changes in gait and speed.
Adaptive coevolutionary networks: a review
Authors: Gross Thilo , Blasius Bernd
Published: October 2007

Adaptive networks appear in many biological applications. They combine topological evolution of the network with dynamics in the network nodes. Recently, the dynamics of adaptive networks has been investigated in a number of parallel studies from different fields, ranging from genomics to game theory. Here we review these recent developments and show that they can be viewed from a unique angle. We demonstrate that all these studies are characterized by common themes, most prominently: complex dynamics and robust topological self-organization based on simple local rules.
Facultative mimicry: cues for colour change and colour accuracy in a coral reef fish
Authors: Cheney Karen L , Grutter Alexandra S , Marshall N. Justin
Published: November 2007

Mimetic species evolve colours and body patterns to closely resemble poisonous species and thus avoid predation (Batesian mimicry), or resemble beneficial or harmless species in order to approach and attack prey (aggressive mimicry). Facultative mimicry, the ability to switch between mimic and non-mimic colours at will, is uncommon in the animal kingdom, but has been shown in a cephalopod, and recently in a marine fish, the bluestriped fangblenny
Plagiotremus rhinorhynchos
, an aggressive mimic of the juvenile cleaner fish
Labroides dimidiatus
. Here we demonstrate for the first time that fangblennies adopted mimic colours in the presence of juvenile cleaner fish; however, this only occurred in smaller individuals. Field data indicated that when juvenile cleaner fish were abundant, the proportion of mimic to non-mimic fangblennies was greater, suggesting that fangblennies adopt their mimic disguise depending on the availability of cleaner fish. Finally, measurements of spectral reflectance suggest that not only do mimic fangblennies accurately resemble the colour of their cleaner fish models but also mimic other species of fish that they associate with. This study provides insights into the cues that control this remarkable facultative mimicry system and qualitatively measures its accuracy.
Evidence for adaptive design in human gaze preference
Authors: Conway C.A , Jones B.C , DeBruine L.M , Little A.C
Published: November 2007

Many studies have investigated the physical cues that influence face preferences. By contrast, relatively few studies have investigated the effects of facial cues to the direction and valence of others' social interest (i.e. gaze direction and facial expressions) on face preferences. Here we found that participants demonstrated stronger preferences for direct gaze when judging the attractiveness of happy faces than that of disgusted faces, and that this effect of expression on the strength of attraction to direct gaze was particularly pronounced for judgements of opposite-sex faces (study 1). By contrast, no such opposite-sex bias in preferences for direct gaze was observed when participants judged the same faces for likeability (study 2). Collectively, these findings for a context-sensitive opposite-sex bias in preferences for perceiver-directed smiles, but not perceiver-directed disgust, suggest gaze preference functions, at least in part, to facilitate efficient allocation of mating effort, and evince adaptive design in the perceptual mechanisms that underpin face preferences.
Robustness and evolvability: a paradox resolved
Authors: Wagner Andreas
Published: October 2007

Understanding the relationship between robustness and evolvability is key to understand how living things can withstand mutations, while producing ample variation that leads to evolutionary innovations. Mutational robustness and evolvability, a system's ability to produce heritable variation, harbour a paradoxical tension. On one hand, high robustness implies low production of heritable phenotypic variation. On the other hand, both experimental and computational analyses of neutral networks indicate that robustness enhances evolvability. I here resolve this tension using RNA genotypes and their secondary structure phenotypes as a study system. To resolve the tension, one must distinguish between robustness of a genotype and a phenotype. I confirm that genotype (sequence) robustness and evolvability share an antagonistic relationship. In stark contrast, phenotype (structure) robustness promotes structure evolvability. A consequence is that finite populations of sequences with a robust phenotype can access large amounts of phenotypic variation while spreading through a neutral network. Population-level processes and phenotypes rather than individual sequences are key to understand the relationship between robustness and evolvability. My observations may apply to other genetic systems where many connected genotypes produce the same phenotypes.
Novosphingobium nitrogenifigens sp. nov., a polyhydroxyalkanoate-accumulating diazotroph isolated from a New Zealand pulp and paper wastewater
Authors: Addison Sarah L. , Foote Sonia M. , Reid Nicola M. , Lloyd-Jones Gareth
Published: October 2007

A diazotroph capable of accumulating significant amounts of polyhydroxyalkanoate was isolated in New Zealand from a bioreactor treating nitrogen-deficient pulp and paper-mill effluent. Strain Y88Tis Gram-negative, rod-shaped and positive for catalase, nitrate reductase and urease activities. The complete 16S rRNA gene sequence was most similar to those of other members of the genusNovosphingobium, the highest level of similarity (94.7 %) being found with respect to the type strain ofNovosphingobium stygium. The combined phenotypic, chemotaxonomic and sequence data show that while strain Y88Tbelongs to the genusNovosphingobium, it is distinct from all currently recognizedNovosphingobiumspecies. Therefore, strain Y88Trepresents the first nitrogen-fixing species of the genusNovosphingobium, for which the nameNovosphingobium nitrogenifigenssp. nov. is proposed. The type strain is Y88T(=ICMP 16470T=DSM 19370T).
Schlesneria paludicola gen. nov., sp. nov., the first acidophilic member of the order Planctomycetales, from Sphagnum-dominated boreal wetlands
Authors: Kulichevskaya Irina S. , Ivanova Anastasia O. , Belova Svetlana E. , Baulina Olga I. , Bodelier Paul L. E. , Rijpstra W. Irene C. , Sinninghe Damsté Jaap S. , Zavarzin George A. , Dedysh Svetlana N.
Published: October 2007

Three strains of budding, ellipsoid-shaped and rosette-forming bacteria were isolated from acidic Sphagnum-dominated boreal wetlands of northern Russia and were designated strains MPL7T, MOB77 and SB2. The presence of crateriform pits and numerous fibrillar appendages on the cell surface and an unusual spur-like projection on one pole of the cell indicated a planctomycete morphotype. These isolates are moderately acidophilic, mesophilic organisms capable of growth at pH values between 4.2 and 7.5 (with an optimum at pH 5.0–6.2) and at temperatures between 4 and 32 °C (optimum 15–26 °C). The major fatty acids are C16 : 0 and C16 : 1
ω7c; the major quinone is MK-6. The G+C content of the DNA is 54.4–56.5 mol%. Strains MPL7T, MOB77 and SB2 possess nearly identical 16S rRNA gene sequences and belong to the planctomycete lineage defined by the genus Planctomyces, being most closely related to Planctomyces limnophilus DSM 3776T (86.9–87.1 % sequence similarity). However, strain MPL7T showed only 28 % DNA–DNA hybridization with P. limnophilus DSM 3776T. Compared with currently described members of the genus Planctomyces, the isolates from northern wetlands do not form long and distinctive stalks, have greater tolerance of acidic conditions and low temperatures, are more sensitive to NaCl, lack pigmentation and degrade a wider range of biopolymers. The data therefore suggest that strains MPL7T, MOB77 and SB2 represent a novel genus and species, for which the name Schlesneria paludicola gen. nov., sp. nov., is proposed. Strain MPL7T (=ATCC BAA-1393T =VKM B-2452T) is the type strain of Schlesneria paludicola.