bluuebunny/crossref_metadata_2025 huggingface dataset:
Simplifying calculations in real time finite temperature field theory
Authors: Fugleberg T , Carrington M E
Published: July 2007

In this paper, we discuss a Mathematica program that we have written that calculates the integrand for amplitudes in the closed-time-path formulation of real-time finite-temperature field theory. The program is designed to be used by someone with no previous experience with Mathematica. It performs contractions over tensor indices that appear in real-time finite-temperature field theory and gives the result in the 1-2, Keldysh or R/A basis. As an illustration of this program, we discuss the calculation of all 3-point ward identities in finite-temperature quantum electrodynamics with full vertices.

PACS Nos.: 11.10.Wx,11.15.-q
Probing new CP-odd thresholds with electric dipole moments
Authors: Ritz A
Published: July 2007

We dicuss the utility of precision probes for flavour-diagonal CP-violation, namely, searches for electric dipole moments of nucleons, atoms, and molecules, in looking for new physics thresholds that manifest themselves primarily through higher dimensional operators. After reviewing the status of the electric dipole moment (EDM) constraints, we consider first the sensitivity to a generic class of dimension-five operators generated at a supersymmetric threshold, through their contribution to CP- and flavour-violating observables. Such thresholds can be probed by EDMs up to a scale of order 108 GeV depending on the flavour structure. We then turn to consider the possibility that electroweak baryogenesis is made feasible by the introduction of dimension-six operators at a TeV-scale threshold. The EDM costraints on dimension-six couplings of the Higgs to the fermions currently still allow a reasonable window in parameter space for these models, but the next generation of experiments should provide a conclusive test.

PACS Nos.: 11.30.Er, 12.60.Fr, 12.60.Jv
Collapse behaviour of unsaturated compacted soil with different initial densities
Authors: Sun De'an , Sheng Daichao , Xu Yongfu
Published: July 2007

Very few experimental data on the mechanical behaviour of unsaturated soils exists, particularly on the collapse behaviour under general stress states, because of the technical difficulties and time-consuming nature of measuring suction and deformation. This paper presents the results of a series of controlled-suction triaxial tests on the collapse behaviour of an unsaturated compacted clay with different initial dry densities and suctions. The collapse behaviour here includes deformation characteristics, such as volume changes, and hydraulic characteristics, such as saturation changes. It is found that the wetting-caused collapse mainly depends on the mean net stress and the initial density, and that the volume decrease reaches a maximum when the specimen is under the initial yielding mean net stress. It is also found that the soil-water characteristic curve in terms of suction and degree of saturation shifts upwards with increasing specimen density. The soil-water characteristic curve of a compacted soil mainly depends upon the current density, not directly upon the stress state. In addition, experimental data show that the collapse occurs mainly in an intermediate range of suction levels, which are neither very high nor very low, and that the wetting-caused volume decrease is accompanied by an increase in the degree of saturation.Key words: unsaturated soil, density, triaxial test, suction, collapse, degree of saturation.
Concerted rate-limiting proton transfer to sulfur with nucleophilic attack at phosphorus — A new proposed mechanism for hydrolytic decomposition of the P=S pesticide, Diazinon, in moderately acidic sulfuric acid media
Authors: Churchill Doreen , Dust Julian M , Buncel Erwin
Published: July 2007

We report herein the first kinetic study of a P=S containing organophosphorus pesticide, Diazinon (1), in the moderately concentrated acid region. Product analyses (31P NMR) show that reaction occurs only at the P centre. The rate-acidity profile (kobs vs. molarity of H2SO4) appears as a curve in which the initial slight downward trace (molarity = 1 to ca. 5) is followed by sharper upward curve (molarity ca. 5 to 14). Using treatments involving the excess acidity (X) method, the A-1 and A-2 mechanistic possibilities were found to be inoperative over the full acidity range. A novel mechanism is proposed for the higher acidity (X ca. 2–6) region. This mechanism involves proton transfer to P=S from hydronium ion with concomitant proton transfer from water, which effectively delivers hydroxide to the P centre in a variant of the A-SE2 process. A putative A-2 mechanism in this region is supplanted by the proposed A-SE2 variant where the cyclic array results in proton transfer being efficiently coupled with nucleophilic attack involving water. This constitutes the first report of rate-limiting proton transfer at the P=S functionality in acid hydrolysis of this class of organophosphorus neutroxins. A 600 000-fold acceleration in the decomposition of Diazinon is associated with the change of medium from neutral aqueous solution to the most acidic medium studied (X ca. 6). Key words: phosphorothioate ester hydrolysis, acid catalysis, rate-limiting proton transfer at P=S, excess acidity analysis, new A-SE2 variant mechanism.
Limitations to photosynthetic carbon gain in timberline Abies lasiocarpa seedlings during prolonged drought
Authors: Johnson Daniel M. , Smith William K.
Published: July 2007

Photosynthesis, water status, and associated physiological parameters were measured in chronically drought-stressed seedlings (5 years of below-average precipitation, 107 cm net deficit) of Abies lasiocarpa (Hook.) Nutt. above (treeline ecotone site, TS) and below (forest site, FS) a Rocky Mountain timberline. In contrast to normal seasonal patterns reported for timberline conifer trees, xylem water potentials were exceptionally low in early summer and remained low for the rest of the summer. Although photosynthesis was not significantly different between the two sites, early season photosynthesis was greater than late-season photosynthesis, especially at FS. Mean daily values of leaf conductance to water vapor (gwv) and transpiration (E) were also low at the beginning of summer (gwv from 0.01 mol·m–2·s–1 to 0.13 mol·m–2·s–1 and E from 0.4 μmol·m–2·s–1 to 2.9 μmol·m–2·s–1) and continued to decrease through summer (an approximate 10-fold decrease in gwv and a 2-fold to 3-fold decrease in E), which resulted in increasing water-use efficiency as summer progressed. Although the slope of instantaneous photosynthesis – intercellular CO2 concentration curves was reduced (lower carboxylation efficiency) from July to September, the relative stomatal limitation to carbon gain was less than 50% over the entire measurement period. Mean daily intercellular CO2 concentrations decreased from near ambient levels (approximately 350–360 ppm) to 290 ppm over the course of summer. Overall, nonstomatal limitations appeared to have the largest impact on photosynthetic carbon gain, although seasonal decreases in leaf conductance and a corresponding depletion of intercellular CO2 indicated that there were also significant stomatal limitations to carbon gain that resulted in a continued regulation of greater water use efficiency.
Field performance and early test results of offspring from two Norway spruce seed orchards containing clones transferred to warmer climates
Authors: Skrøppa Tore , Kohmann Ketil , Johnsen Øystein , Steffenrem Arne , Edvardsen Øyvind M.
Published: July 2007

We present results from early tests and field trials of offspring from two Norway spruce ( Picea abies (L.) Karst.) seed orchards containing clones that have been transferred from high altitudes to sea level and from northern to southern latitudes. Seedlings from seeds produced in the low-altitude seed orchard developed frost hardiness later at the end of the growth season, flushed later in field trials, and grew taller than seedlings from seeds produced in natural stands. They had the lowest mortality rate and the lowest frequency of injuries in the field trials. Similar results were observed in seedlings from seeds produced in the southern seed orchard. We found no adverse effects of the changed growth rhythm. Seedlings from two seed crops in the southern orchard, produced in years with a warm and a cold summer, had different annual growth rhythms. The results are explained mainly by the effects of the climatic conditions during the reproductive phase. Seed crops from different years in the same seed orchard may produce seedlings that perform as if they were from different provenances. It is argued that the effects of the climatic conditions during seed production must contribute to the variation among provenances of Norway spruce.
Forest dynamics following spruce budworm outbreaks in the northern and southern mixedwoods of central Quebec
Authors: Bouchard Mathieu , Kneeshaw Daniel , Messier Christian
Published: July 2007

The effects of 20th century spruce budworm ( Choristoneura fumiferana (Clem.)) outbreaks on forest dynamics was examined in the southern and northern parts of the mixedwood forest zone in central Quebec, Canada. In each region, three study areas were placed in unmanaged stands that had not burned for more than 200 years. Disturbance impacts and forest succession were evaluated using aerial photographs and dendrochronology. Spruce budworm outbreaks occurred around 1910, 1950, and 1980 in both regions. The 1910 outbreak seemed to have limited impact in both regions, and the 1950 outbreak caused heavy mortality in conifer stands (mostly of balsam fir, Abies balsamea (L.) Mill.) in the southern region. The 1980 outbreak caused major mortality in the northern region, but had little impact in the southern region. Successive spruce budworm outbreaks led to a massive invasion by hardwood species in the last century in the southern region but not in the northern region. The reason for such contrasting dynamics between regions is unknown, but we hypothesize that differences in disturbance intensities, influenced by climate, played a major role. Results from this study emphasize that generalizations about the effect of spruce budworm outbreaks on forest dynamics cannot be derived from observations made during a single outbreak or at a single location.
Riparian forest harvesting and its influence on benthic communities of small streams of sub-boreal British Columbia
Authors: Melody K. Jill , Richardson John S.
Published: July 2007

Forest harvesting in riparian areas can alter the leaf-litter inputs, shading, and stability of small streams, and many of the details of these impacts are known for coastal streams of the Pacific Northwest. However, little is known about how small streams in the drier, continental areas of western North America respond to logging. We conducted a study of paired stream reaches (comparing one recently harvested (≤3 years) reach and two upstream, forested reaches in each of five streams) in which periphyton, detritus, macroinvertebrate abundance and biomass, and physical features were measured in summer and autumn. In general, recently harvested stream sections tended to be wider and contained more riffle areas than the upstream forested sections. The amounts of leaf litter and algae varied among streams and were not consistently greater or lesser in the forested sections than in the harvested sections. Though the variation in amounts within streams was mainly seasonal, amounts differed more among streams than between pairs of harvested and forested reaches. The communities of benthic invertebrates differed significantly between forested and harvested reaches, but often in opposite directions between streams. The magnitude and direction of differences observed between treatments, streams, or seasons were associated with the specific stream and the method of riparian harvesting used.
Fertilization ensures rapid formation of ground vegetation on cut-away peatlands
Authors: Huotari Noora , Tillman-Sutela Eila , Kauppi Anneli , Kubin Eero
Published: July 2007

Mechanical harvesting of peatlands completely changes the original bog ecosystem and without afteruse causes long-lasting disturbance in the environment due to the limited restoration capacity of the habitat. We studied the effects of fertilization on the establishment of vegetation on a cut-away peatland in Finland. Six treatments of different quantities and mixtures of wood ash, peat ash, biotite, or forest P–K fertilizer were replicated in three plots. Although all the fertilizers accelerated the revegetation of a cut-away peatland significantly, ash-based fertilizers had the greatest and most immediate impact on the formation of vegetation. Ash fertilizers especially increased the coverage of small fire-loving moss species such as Ceratodon purpureus (Hedw.) Brid., Funaria hygrometrica Hedw., and Leptobryum pyriforme (Hedw.) Wils. in the early stages of the succession. Furthermore, the succeeding coverage of vascular plants improves nutritional conditions through the rapid accumulation and decomposition of plant-derived litter. The rapid formation of ground vegetation on bare peat surface after ash fertilizer application indicated that wood and peat ash are suitable for mined peatlands. This being the case, peat and wood ash should be regarded more as a recyclable constituent rather than as waste in afforestation of cut-away peatlands.
An experimental evaluation of fire history reconstruction using dendrochronology in white oak (Quercus alba)
Authors: McEwan Ryan W. , Hutchinson Todd F. , Ford Robert D. , McCarthy Brian C.
Published: July 2007

Dendrochronological analysis of fire scars on tree cross sections has been critically important for understanding historical fire regimes and has influenced forest management practices. Despite its value as a tool for understanding historical ecosystems, tree-ring-based fire history reconstruction has rarely been experimentally evaluated. To examine the efficacy of dendrochronological analysis for detecting fire occurrence in oak forests, we analyzed tree cross sections from sites in which prescribed fires had been recently conducted. The first fire in each treatment unit created a scar in at least one sample, but the overall percentage of samples containing scars in fire years was low (12%). We found that scars were created by 10 of the 15 prescribed fires, and the five undetected fires all occurred in sites where fire had occurred the previous year. Notably, several samples contained scars from known fire-free periods. In summary, our data suggest that tree-ring analysis is a generally effective tool for reconstructing historical fire regimes, although the following points of uncertainty were highlighted: (i) consecutive annual burns may not create fire scars and (ii) wounds that are morphologically indistinguishable from fire scars may originate from nonfire sources.
EFFECT OF MAGNETIC FIELDS ON BINDING ENERGY OF IMPURITY STATES IN A SEMIMAGNETIC PARABOLIC QUANTUM DOT
Authors: PETER A. JOHN
Published: August 2007

Using a variational approach, the binding energy of shallow hydrogenic impurities in a semimagnetic parabolic quantum dot is calculated within the effective mass approximation. The binding energy is computed for Cd 1-x in Mn x in Te / Cd 1-x out Mn x out Te structures as a function of the dot size in an external magnetic field. The results show that the impurity binding energy (i) increases with the reduction in dot sizes (ii) decreases when the magnetic field is increased for a given dot and (iii) increases to a maximum value at 100 Å and then decreases as the size of the dot increases beyond 100 Å for a realistic model. Spin polaronic shifts are estimated using a mean field theory. These results are compared with the existing literatures.
RETROFIT OF EXISTING BUILDINGS FOR EARTHQUAKE RESISTANCE
Authors: TAN K. H. , BALENDRA T.
Published: August 2007

Buildings sited on soft soils are sometimes subjected to tremors due to earthquakes occurring some 400 to 700 kilometers away as a result of the amplifying effect of soft soils on low-frequency, long-distance waves. This study focuses on the seismic vulnerability of existing reinforced concrete (RC) buildings in Singapore that are designed primarily for gravity loads, and examines the use of externally bonded glass fiber-reinforced polymer (FRP) systems in retrofitting these buildings to resist lateral forces due to seismic action. Two case studies were considered: (1) a four-story frame building, representing typical low-rise buildings; and (2) a 25-story shear wall-frame building, representing typical high-rise buildings. Pushover tests were carried out correspondingly on 1/2-scale sub-frames and 1/5-scale shear walls. The one-and-a-half bay, two-storey frame specimens represent the critical part of the low-rise building while the I-shaped wall specimens represent the lower critical 2.6 stories of the high-rise building. Test results revealed a strong column–weak beam failure mechanism for both the un-retrofitted and retrofitted frames. The retrofitted frame was 30 percent higher in ultimate strength but 12 percent lesser in ultimate drift ratio compared to the un-retrofitted frame. For the wall specimens, sudden failure of the un-retrofitted shear wall was observed at the base of the side walls due to shear. Failure of the retrofitted wall was however more ductile with FRP debonding, followed by concrete crushing and FRP rupture at the compressive base of the side wall. The ultimate load capacity and lateral displacement of the retrofitted wall increased respectively by 45 and 66 percent.
Adaptation to Environmental Change: Contributions of a Resilience Framework
Authors: Nelson Donald R. , Adger W. Neil , Brown Katrina
Published: July 2007

Adaptation is a process of deliberate change in anticipation of or in reaction to external stimuli and stress. The dominant research tradition on adaptation to environmental change primarily takes an actor-centered view, focusing on the agency of social actors to respond to specific environmental stimuli and emphasizing the reduction of vulnerabilities. The resilience approach is systems orientated, takes a more dynamic view, and sees adaptive capacity as a core feature of resilient social-ecological systems. The two approaches converge in identifying necessary components of adaptation. We argue that resilience provides a useful framework to analyze adaptation processes and to identify appropriate policy responses. We distinguish between incremental adjustments and transformative action and demonstrate that the sources of resilience for taking adaptive action are common across scales. These are the inherent system characteristics that absorb perturbations without losing function, networks and social capital that allow autonomous action, and resources that promote institutional learning.
Electrochemical Reduction of Carbon Dioxide for Fuel Cell Utilisation
Authors: Goncalves Marta C. , Condeco Jose A. , Pardal Tiago C. , Roncero Daniel M. , Santos Diogo M. , Sequeira Cesar A.
Published: August 2007

The perception that new alternatives are required for energy conversion systems has led our group to be innovative on processes regarding energy storage and transportation. The purpose of this project was to investigate the viability of an energy storage system based on a carbon dioxide electroreduction process. In this system, CO2 is converted to potential energy sources (hydrocarbon products) that can be easily stored. The aerospace applications and the potential for technology transfer for terrestrial applications in the frame of the Kyoto agreement are discussed. The experimental results obtained for the carbon dioxide electroreduction are presented, namely the analysis of the reaction products by gas chromatography.
Semiconductor Oxides as Electron Acceptors in Hybrid Organic-Inorganic Solar Cells
Authors: Lira-Cantu Monica , Norrman Kion , Andreasen Jens , Casan-Pastor Nieves , Krebs Frederik C.
Published: August 2007

Hybrid Solar Cells (HSCs) were prepared as bi-layers between thin film semiconductor oxides (TiO2, Nb2O5 and ZnO) made by the sol-gel solution and the polymer MEH-PPV, applying a final device configuration ITO/Oxidethin film/MEH-PPV/Ag. We have analyzed the photovoltaic response in terms of inert atmosphere by recording the initial values of open circuit voltage (Voc) and current density (Jsc) and also by analyzing the corresponding IV-curves. We report in this work the improvement observed in Jsc, Voc and IV-curves when HSCs are transferred from inert conditions to ambient atmosphere. The effect is observed regardless of the semiconductor oxide applied and has been attributed to the reversible incorporation of oxygen from the atmosphere into the semiconductor oxide surface during illumination.
Effects of Cr on the Structure of the Passive Films on Ni-(15, 30)Cr
Authors: Jang Heejin , Kwon Hyuksang
Published: August 2007

The structure of the passive films formed on Ni-(15, 30)Cr in pH 8.5 buffer solution and in pH 2.0 sulfuric acid solution was investigated by examining the chemical composition and the electronic properties of the films. The concentration of Cr in the passive film formed on Ni-(15, 30)Cr was increased with increase in Cr content in the alloy and decrease of solution pH from the XPS depth profiles. The photocurrent spectra for the passive films formed on Ni-(15, 30)Cr alloys in pH 8.5 buffer solution were found to be generated by NiO, Ni(OH)2, and Cr(OH) 3. The chemical composition and the capacitance behavior suggested that the base structure and electronic properties of the Ni-rich or Ni-Cr mixed oxide films on Ni-(15, 30)Cr alloys are dominated by Ni oxide, whereas those for the highly Cr- enriched film on Ni-30Cr is determined by Cr oxide.
Study of Anaerobic Biofilms from Gasoline Distribution Pipelines
Authors: Ramírez Espinosa Dalinda , Domínguez Benetton Xochitl
Published: August 2007

Petroleum, gas, shipping and water treatment and distribution industries are significantly affected by microbial activity-environments in which biofilms might cause or serious problems such as biofouling, biodeterioration and biocorrosion, which are usually associated with great human, environmental and financial losses. The present work has as a main objective the biological and electrochemical characterization using electrochemical impedance spectroscopy of the anaerobic microorganisms present in gasoline distribution pipelines that might have an influence in corrosion processes, specifically focusing on those biofilm-developers. Several microorganisms have been isolated and their metabolic activities monitored, as well as their electrochemical influence over carbon steel in laboratory conditions.
Conductive Diamond Powder: A New Catalyst Support for the Polymer Electrolyte Membrane Fuel Cell
Authors: Swope V. , Sasaki I. , Ay Ayten , Swain G. M.
Published: August 2007

Previously, our group reported on the preparation and electrochemical properties of a low surface area conductive diamond powder (1). We now demonstrate successful preparation of higher surface area conductive diamond powders ranging from 8 to 52 m2/g. Electrical resistance measurements show these boron-doped diamond powders are nearly as conductive as Vulcan powder. The cost of diamond powder is compared with the cost of other carbon materials used in the PEMFC. Structural and morphological characteristics of the diamond powders are investigated using Raman spectroscopy and scanning electron microscopy.
Modifying the Reactivity of Reduced Intermediates of Quinones by Structural Changes and Intra and Inter Molecular Hydrogen Bonding
Authors: Gonzalez Felipe J. , Astudillo Pablo D. , Magali Salas , Macías-Ruvalcaba Norma A. , Bautista Martinez Jose Antonio A. , Aguilar-Martinez Martha , Gómez Martin , Frontana Carlos E. , Gonzalez I.
Published: August 2007

In this work, it is presented a review on several mechanistic aspects of the electrochemistry of quinones. It is discussed how the reduced intermediates, the radical anion and dianion, can be stabilized by non-covalent interactions. The intrinsic stability is a factor which can be controlled by selecting appropriately structures containing electron-withdrawing substituents, or β-hydroxy groups in possibility to establish intramolecular hydrogen bonds with the negative oxygen of the quinone reduced intermediates. Alternatively, a higher degree of stabilization can be gained when external hydrogen bonding donors are present in the medium of reaction. Weak and strong hydrogen bonding interactions are possible, however, overshooting the limit of strong interactions, proton transfer processes can occurs following a wide variety of mechanisms, whose pathway depends on the relationship between basicity of the reduced species and acidity of the proton donors.
Intra vs Intermolecular Association Processes in the Radical Anions of b-Hydroxyquinones. Influence on the Structural Properties of the Radical Anion of Julgone.
Authors: Frontana Carlos E. , Gómez Martin , González Ignacio
Published: August 2007

The electrochemical study of the β-hydroxyquinone Juglone by cyclic voltammetry and double step potential chronoamperometry is presented in this work. The results show that the electroreduction of Juglone at the first electron transfer process in DMSO is determined by the extent of the reduction of the self-associated quinone as a homoconjugate, which changes the reduction pathway for this compound at high concentrations. This set of reactions is associated to the presence of a selfprotonation process mediated by the formation of the homoconjugate. The changes in structure of the semiquinone analyzed by Electron Spin Resonance spectroelectrochemical experiments confirms the change in the structural properties of the corresponding semiquinones.
Electrochemical Study of Benzodiazepines Derivatives Applied to the Analysis of Structure-Activity Relationships and Interactions with Membrane Models
Authors: Monzón Lorena M. , Yudi Lidia M.
Published: August 2007

Cyclic voltammetry was applied at the water/1,2 - dichloroethane interface to study the transfer of a series of benzodiazepines. Transfer potentials were determined with the aim to correlate the partition coefficient of these compounds with the presence of different substituents and its biological activity. On the other hand, the effect of Flunitrazepam (a benzodiazepine) on the organization and permeability of lipidics monolayers adsorbed at the interface was analyzed by cyclic voltammetry and electrochemical spectroscopy impedance. These results contribute to studies of quantitative structure - activity relationships and also to those related with to non - specific interaction of these drugs with biological membranes.
Interaction Between Fe(II) and 1-4,Dihydroxyanthraquinone: an Spectroscopic and Electrochemical Study
Authors: Gonzalez I. , Morales Adriana , Gonzalez Felipe J. , Moya Rosario , Gómez Martin
Published: August 2007

The 1,4 dihydroxyanthraquinone is a part of some antineoplasic drugs structure, these drugs interact directly with DNA. Daunomicine-DNA complexes can be stabilized by hydrogen bonding interactions, the anthraquinone structure remains intact and toxic effects come from its reduction to semiquinone. In order to diminish the daunomicine adverse effects, it is mixed with metallic ions, mainly Fe(II). The UV- vis spectrophotometric study proves the Fe(II) coordination by the 1-4, dihydroxyanthraquinone through the oxygen atoms from the carbonyl and phenyl groups, to produced a 1:1 complex ([Fe (II)H2Q]), leaving the other phenyl group as hydrogen bonding donor. The electrochemical reduction process for the produced complex becomes complicated due to its characteristics: it shows not only charge transference but also proton transfer processes. The [Fe(II)H2Q] complex presents three different reduction process where a quinone radical species is produced for each one and every species differ in the number of hydrogen atoms.
Coordinated Nanobiosensors for Enhanced Detection: Integration of Three Dimensional Structures to Toxicological Applications
Authors: Yeh Joanne I. , Du Shoucheng , Xia Tian , Lazareck Adam , Kim Jin H. , Xu Jimmy , Nel Andre E.
Published: August 2007

A strategy of metallizing peptides to serve as conduits of electronic signals that bridge between a redox enzyme and a carbon-nanotube electrode has been developed with enhanced results. Our approach (1) conformationally stabilizes the state of the enzyme relative to the electrode surface. Scanning electron microscopy confirms immobilization and linking of the assembly specifically to the tips of carbon nanotube electrodes. Isothermal titration calorimetry and mass spectrometry indicate a binding stoichiometry of at least three metals bound per peptide strand. The crystal structure of the peptide, solved by X-ray crystallography to 1.6 Aå resolution, reveals high structural integrity. The sensitivity of this system to detect and semi-quantitate reactive oxygen species generated in situ by various nanomaterials was recently demonstrated (2). Overall, these results highlight the gain that can be achieved when the signal tranducing units of a biosensor are aligned through directed peptide chemistry.
Two isoforms of PSAP/MTCH1 share two proapoptotic domains and multiple internal signals for import into the mitochondrial outer membrane
Authors: Lamarca Violeta , Sanz-Clemente Antonio , Pérez-Pé Rosaura , Martínez-Lorenzo María José , Halaihel Nabil , Muniesa Pedro , Carrodeguas José A.
Published: August 2007

Presenilin 1-associated protein (PSAP) was first identified as a protein that interacts with presenilin 1. It was later reported that PSAP is a mitochondrial protein that induces apoptosis when overexpressed in cultured cells. PSAP is also known as mitochondrial carrier homolog 1 (Mtch1). In this study, we show that there are two proapoptotic PSAP isoforms generated by alternative splicing that differ in the length of a hydrophilic loop located between two predicted transmembrane domains. Using RT-PCR and Western blot assays, we determined that both isoforms are expressed in human and rat tissues as well as in culture cells. Our results indicate that PSAP is an integral mitochondrial outer membrane protein, although it contains a mitochondrial carrier domain conserved in several inner membrane carriers, which partially overlaps one of the predicted transmembrane segments. Deletion of this transmembrane segment impairs mitochondrial import of PSAP. Replacement of this segment with each of two transmembrane domains, with opposite membrane orientations, from an unrelated protein indicated that one of them allowed mitochondrial localization of the PSAP mutant, whereas the other one did not. Our interpretation of these results is that PSAP contains multiple mitochondrial targeting motifs dispersed along the protein but that a transmembrane domain in the correct position and orientation is necessary for membrane insertion. The amino acid sequence within this transmembrane domain may also be important. Furthermore, two independent regions in the amino terminal side of the protein are responsible for its proapoptotic activity. Possible implications of these findings in PSAP function are discussed.
Contractile and connective tissue protein content of human skeletal muscle: effects of 35 and 90 days of simulated microgravity and exercise countermeasures
Authors: Haus Jacob M. , Carrithers John A. , Carroll Chad C. , Tesch Per A. , Trappe Todd A.
Published: August 2007

We examined the effects of 35 and 90 days of simulated microgravity with or without resistance-exercise (RE) countermeasures on the content of the general skeletal muscle protein fractions (mixed, sarcoplasmic, and myofibrillar) and specific proteins that are critical for muscle function (myosin, actin, and collagen). Subjects from two studies, using either unilateral lower limb suspension (ULLS) or bed rest (BR), comprised four separate groups: 35 days ULLS ( n =11), 35 days ULLS+RE ( n = 10), 90 days BR ( n = 9), and 90 days BR+RE ( n = 8). RE consisted of four sets of seven maximal concentric and eccentric repetitions of the quadriceps femoris muscles that were performed 2 or 3 times per week. Pre- and post-simulated weightlessness muscle biopsies were analyzed from the vastus lateralis of all groups and the soleus of the 35-day ULLS and 90-day BR groups. The general protein fractions and the specific proteins myosin, actin, and collagen of the vastus lateralis were unchanged ( P > 0.05) in both control and countermeasures groups over 35 and 90 days, despite large changes in quadriceps femoris muscle volume (35 days ULLS: −9%, 35 days ULLS+RE: +8%; and 90 days BR: −18%, 90 days BR+RE: −1%). The soleus demonstrated a decrease in mixed (35 days ULLS: −12%, P = 0.0001; 90 days BR: −12%, P = 0.004) and myofibrillar (35 days ULLS: −12%, P = 0.009; 90 days BR: −8%, P = 0.04) protein, along with large changes in triceps surae muscle volume (35 days ULLS: −11%; 90 days BR: −29%). Despite the loss of quadriceps femoris muscle volume or preservation with RE countermeasures during simulated microgravity, the quadriceps femoris muscles are able to maintain the concentrations of the general protein pools and the main contractile and connective tissue elements. Soleus muscle protein composition appears to be disproportionately altered during long-duration simulated weightlessness.
Differential effects of dialysis and ultrafiltrate from individuals with CKD, with or without diabetes, on platelet phosphatidylserine externalization
Authors: Wang Yingjie , Beck Werner , Deppisch Reinhold , Marshall Sally M. , Hoenich Nicholas A. , Thompson Michael G.
Published: August 2007

Individuals with chronic kidney disease (CKD) and/or diabetes mellitus (DM) are at increased risk of cardiovascular events and have elevated externalization of phosphatidylserine (PS; which propagates thrombus formation) in a small subpopulation of platelets. The purpose of this study was to examine the effect of 1) removing uremic toxins by hemodialysis on PS externalization in patients with either CKD or CKD and DM and 2) ultrafiltrate (UF) from these individuals on PS externalization in healthy platelets. PS externalization was quantified by a fluorescence-activated cell sorter using annexin V in platelet-rich plasma. PS externalization was elevated threefold in CKD patients and returned to basal values during 3-h hemodialysis. In contrast, it was elevated fivefold in individuals with CKD and DM and was still threefold above control after 3-h treatment. UF significantly increased PS externalization in a small subpopulation of platelets from healthy controls. The effect of UF from individuals with CKD and DM was significantly greater than that from patients with CKD alone, and the responses were partially inhibited by the protein kinase Cδ (PKCδ) inhibitor rottlerin and the 5-hydroxytryptamine (5-HT)2A/2Creceptor antagonist ritanserin. The data suggest that uremic toxins present in UF mediate PS externalization in a small subpopulation of platelets, at least in part, via the 5-HT2A/2Creceptor and PKCδ and demonstrate that DM further enhances platelet PS externalization in CKD patients undergoing hemodialysis. This may explain, at least in part, the additional increase in vascular damage observed in CKD patients when DM is present.
Load-mediated downregulation of myostatin mRNA is not sufficient to promote myofiber hypertrophy in humans: a cluster analysis
Authors: Kim Jeong-su , Petrella John K. , Cross James M. , Bamman Marcas M.
Published: August 2007

Myostatin is a potent inhibitor of myogenesis; thus differential expression might be expected across individuals varying in responsiveness to myogenic stimuli. We hypothesized that myostatin would be differentially regulated across humans with markedly different hypertrophic responses to resistance training (RT; 16 wk). Targets were assessed in muscle biopsies at baseline (T1) and 24 h after the first (T2) and last (T3) loading bouts in previously untrained subjects statistically clustered based on mean myofiber hypertrophy as extreme (Xtr; n = 17, 2,475 μm2), modest ( n = 32, 1,111 μm2), and nonresponders ( n = 17, −16 μm2). We assessed protein levels of latent full-length myostatin protein complex and its propeptide; mRNA levels of myostatin, cyclin D1, p21cip1, p27kip1, and activin receptor IIB; and serum myostatin protein concentration. Total RNA concentration increased by T3 in nonresponders (37%) and modest responders (40%), while it increased acutely (T2) only in Xtr (26%), remaining elevated at T3 (40%). Myostatin mRNA decreased at T2 (−44%) and remained suppressed at T3 (−52%), but not differentially across clusters. Cyclin D1 mRNA increased robustly by T2 (38%) and T3 (74%). The increase at T2 was driven by Xtr (62%, P < 0.005), and Xtr had the largest elevation at T3 (82%, P < 0.001). No effects were found for other target transcripts. Myostatin protein complex increased 44% by T3 ( P < 0.001), but not differentially by cluster. Myostatin protein complex propeptide and circulating myostatin were not influenced by RT or cluster. Overall, we found no compelling evidence that myostatin is differentially regulated in humans demonstrating robust RT-mediated myofiber hypertrophy vs. those more resistant to growth.
Lock-and-Key Mechanisms of Cerebellar Memory Recall Based on Rebound Currents
Authors: Wetmore Daniel Z. , Mukamel Eran A. , Schnitzer Mark J.
Published: August 2007

A basic question for theories of learning and memory is whether neuronal plasticity suffices to guide proper memory recall. Alternatively, information processing that is additional to readout of stored memories might occur during recall. We formulate a “lock-and-key” hypothesis regarding cerebellum-dependent motor memory in which successful learning shapes neural activity to match a temporal filter that prevents expression of stored but inappropriate motor responses. Thus, neuronal plasticity by itself is necessary but not sufficient to modify motor behavior. We explored this idea through computational studies of two cerebellar behaviors and examined whether deep cerebellar and vestibular nuclei neurons can filter signals from Purkinje cells that would otherwise drive inappropriate motor responses. In eyeblink conditioning, reflex acquisition requires the conditioned stimulus (CS) to precede the unconditioned stimulus (US) by >100 ms. In our biophysical models of cerebellar nuclei neurons this requirement arises through the phenomenon of postinhibitory rebound depolarization and matches longstanding behavioral data on conditioned reflex timing and reliability. Although CS–US intervals <100 ms may induce Purkinje cell plasticity, cerebellar nuclei neurons drive conditioned responses only if the CS–US training interval was >100 ms. This bound reflects the minimum time for deinactivation of rebound currents such as T-type Ca2+. In vestibulo-ocular reflex adaptation, hyperpolarization-activated currents in vestibular nuclei neurons may underlie analogous dependence of adaptation magnitude on the timing of visual and vestibular stimuli. Thus, the proposed lock-and-key mechanisms link channel kinetics to recall performance and yield specific predictions of how perturbations to rebound depolarization affect motor expression.
Patent Foramen Ovale Closure by Radiofrequency Thermal Coaptation
Authors: Hara Hidehiko , Jones Thomas K. , Ladich Elena R. , Virmani Renu , Auth David C. , Eichinger Joseph E. , Sommer Robert J. , Van Tassel Robert A. , Schwartz Robert S.
Published: July 2007

Background—

Percutaneous transcatheter patent foramen ovale (PFO) closure is now standard practice and may limit embolic complications for at least 10 years. Implantable PFO closure devices may be complicated by thrombosis, infection, device fracture, or embolization. A novel strategy uses radiofrequency-based thermal energy to seal PFO membranes, with no implanted device. We successfully used this method and examined histopathologic events in swine to characterize safety and efficacy.

Methods and Results—

Thirteen domestic swine were examined over time after thermal PFO closure. Three animals were euthanized within 1 hour of treatment, 5 after 7 days, and 5 at 28 days. Gross and histopathologic findings were examined. Radiofrequency energy was delivered successfully in all cases, and PFOs were closed in 12 of 13 cases. One case was not suitable for histological examination because of laceration at euthanasia, and the other PFO was clinically closed, with no shunt at 7 days, but was histologically open. All of the other PFOs were confirmed closed histologically. Acute histological results showed edema, hemorrhage, and myocyte necrosis. Minimal thrombus formation occurred on the left atrial endocardial surface. At day 7, transmural thermal effects occurred through the atrial wall that extended to the epicardial surface. At day 28, thermal effects showed excellent scar formation. Collagen, matrix, and neovascularization were present in all cases. No animal experienced adverse events.

Conclusions—

Thermal PFO closure is feasible, safe, and effective in swine. Thermal healing is nearly complete by 4 weeks and consists of collagen formation and tunnel closure. This technique may allow substantial reduction in PFO closure risk over current device-based therapy.
The Admonition to Assemble Together in Didache 16.2 Reappraised
Authors: Khomych Taras
Published: July 2007

This contribution focuses on the analysis of a largely neglected passage of the Didache 16.2. After a short overview of some approaches to its interpretation, it attempts to shed some more light on the understanding of this section, adapting Milavec's recent theory about the unity of the Didache and progression of thought within it, while modifying his interpretation of this specific passage. Based on the analysis of the passage and its context, this study concludes that Did. 16.2 gives an admonition to the local community to assemble together in unity. This interpretation is further supported by the analysis of the implied military imagery of Did. 16 and correspondences between the passage in question and references to the eucharist in Did. 9-10 and 14. At the same time, this paper points out that Did. 16.2 is distinct from the other eucharistic passages of the Didache as it contains a reminder of community's responsibility in view of the coming end and presents the local liturgical congregation as an image of the final gathering of the Church in the eschaton.
"Judaizing" Christian Interpretations of the Prophets As Seen by Saint Jerome
Authors: Graves Michael
Published: July 2007

Among the many differing interpretations reported by St. Jerome is the set ascribed to "our Judaizers," who are in reality Christian interpreters with whom Jerome disagrees. In his own exegesis of the prophets, Jerome accepts both the literal/historical meaning of the "Hebrews" (Jews) as it relates to Israel's past (Old Testament history), and the spiritual/allegorical meaning of the church as it relates to the present or future. The interpretations that Jerome regards as "Judaizing" are almost all attempts to assign a literal meaning to the future. It is this combination (literal and future) that Jerome rejects as "Judaizing."
Demons and Divine Illumination: A Consideration of Eight Prayers by Gregory of Nazianzus
Authors: Kalleres Dayna
Published: July 2007

This article considers eight prayers by Gregory of Nazianzus (Patrologia Graeca 37.1397-1406) that are singular in their anti-demonic tone and apotropaic formulae. Reading these texts in light of Gregory's Orations 20, 27, and 38-40 elucidates the Cappadocian's connection between baptism and the acquisition of divine knowledge; thus, we can acquire a rare view into the practical aspects of Gregory's endeavors with theoria in his post-baptismal life. Finally, these prayers bring into sharp relief the consequential materiality of the devil and demons in Gregory of Nazianzus' epistemology, theology, and asceticism. In so doing, this essay seeks to turn attention to the vibrant demonologies cultivated and constructed by elite, educated Christians in the late antique cities of the Greek East.
The Authenticity of Maximus the Confessor's Letter to Marinus: The Argument from Theological Consistency
Authors: Siecienski A. Edward
Published: July 2007

Maximus the Confessor's Letter to Marinus (PG 91, 136) has been used throughout the centuries by both Latins and Greeks to defend their respective positions vis-à-vis the filioque. Yet doubts about its authenticity, raised by both sides, have prevented its acceptance as representative of the consensus patrum on the procession of the Holy Spirit. This paper argues that the best case for the authenticity of the Letter, all other doubts aside, is its consistency with the trinitarian principles Maximus inherited from the earlier fathers and established in his other works. For this reason the Letter to Marinus continues to offer modern theologians and ecumenists the best hope for resolving the age old question of the filioque based on the earliest known patristic reference to the debate.
Alternative Explanation for Low Open Circuit Voltage Using Sm‐Doped Ceria Electrolytes in Sofcs
Authors: Miyashita Tomofumi
Published: July 2007

In this paper, using experimental results [1], empirical equations [2], and the concept of effective carriers while hopping in ionic conduction, an alternative explanation is discussed for open circuit voltage (OCV) using Sm‐doped Ceria electrolytes (SDC) in solid oxide fuel cells (SOFCs). Consequently, one chapter of the standard textbook [3] must be entirely modified. This alternative explanation not only coexists with major existing experimental results but also is useful for explaining minor experimental results. An experimental method is proposed to clarify the theoretical consideration.
Design of Mechanical Testing Specimens for Rubber Material Using Finite Element Analysis
Authors: Woo Chang‐Su , Kim Wan‐Doo
Published: July 2007

The material properties of rubber were determined by the experiments of simple tension, simple compression tension, pure shear, equi‐biaxial tension test. In simple tension test, dumbbell specimen is generally used to obtain a state of pure tensile strain. It is shown that a narrow strip specimen for length is over 10 times of the width can be also used in. In simple compression test, the effect of the friction force between the specimen and the platen is investigated. The test device with the tapered platen is proposed to overcome the effect of friction. It is verified by experimental and finite element analysis results. In pure shear tests, it is shown that the width of specimen must be at least 10 times of the height. Specimen and equipment of equi‐biaxial tension was development a state of strain equivalent to pure compression.
Semi‐Empirical Modeling of Gas Permeability Induced by Multilayer Matrix Cracks in Composite Laminates
Authors: Yokozeki Tomohiro
Published: July 2007

Gas permeability through damage networks in composite laminates is the key issue for the applicability of high‐performance composites to the cryogenic propellant tanks of space launch vehicles. A simple model for the gas permeability induced by multilayer matrix cracks in composite laminates is proposed based on the leak conductance at crack intersections, which is an extension of the model by Kumazawa et al (AIAA J. 41, 2037‐ ‐2044, 2003). Experimental evidence on the gas permeability mechanisms is summarized and reflected in the present model. In order to include the effects of applied loadings and damage sizes on the gas permeability, the leak conductance is assumed to be a function of the average crack opening displacements of the matrix cracks and the crack intersection angles. The leak conductance factor was empirically obtained as a function of the crack intersection angle, and the comparison of the gas permeability between the predictions based on the developed model and the experimental results is presented for the validity of this model.