bluuebunny/crossref_metadata_2025 huggingface dataset:
The interaction of nitrogen with tungsten and iridium
Authors: Knor Zlatko , Kuchynka Karel
Published: September 2010

The interaction of an iridium filament with nitrogen, thermally activated at the tungsten filament, was studied at low pressures. The activated nitrogen is chemisorbed at iridium and at room temperature it reacts with hydrogen, yielding ammonia.
Unusually high values of the quotient d ln η/d ln M of some low-molecular-weight liquid polymers
Authors: Bohdanecký Miloslav , Kaštánek Alois , Lešek František
Published: September 2010

Unusually high values of the quotient d ln η/d ln M ≡ a (where η is viscosity and M is molecular weight) found for some low-molecular-weight liquid polymers (4 ⪬ a ⪬ 8) are discussed in terms of the theory of flow processes of polymeric liquids. The effect is assigned mainly to the dependence on the chain length of the friction factor per main chain atom or atomic group but deviations of short chains from the conformation of random coils can also contribute significantly. The variation of the quotient a with temperature, however, is due to the former factor only.
Collapse of a single polystyrene chain in dioctyl phthalate: Effect of molecular weight
Authors: Štěpánek Petr , Koňák Čestmír
Published: September 2010

The use of a viscous solvent (dioctyl phthalate) made possible an investigation of the whole coil-globule transition of polystyrene chains in dilute solution. For values of the reduced temperature variable τ√M lower than - 230 the globular polymer region was observed in which the radius R and the molecular weight M are related by R ~ M1/3. The range of the Θ region where the expansion factor α is a linear function of τ√M was determined as -50 < τ√M < 50. It was shown that within the whole temperature range investigated the expansion factor is a universal function of the variable τ√M. The polymer dimensions at the Θ temperature are higher by some 15% in this solvent than in cyclohexane; also, the width of the transition region is much larger.
Effect of mode separation on the decomposition rate of polyatomic molecules
Authors: Šolc Milan
Published: September 2010

A generalized equation for the unimolecular rate constant in the low-pressure region is used to estimate the effect of mode separation on decomposition rate. The controlling factor in determining the degree of ergodicity of the dynamics, and hence the decomposition rate, is the number of mode sets between which energy exchange is frozen. The distribution of modes within the sets is not crucial.
The deuterium interaction with tungsten and iridium in the UHV system
Authors: Kuchynka Karel , Knor Zlatko
Published: September 2010

The behaviour of hydrogen, in its contact with the iridium and the tungsten filament kept at different temperatures, was studied in the pressure range 1.3 . 10-6 - 1.3 . 10-3 Pa, in a glass apparatus. The effects of adsorption, atomization, desorption, recombination of atoms and chemical reactions were investigated as a function of temperature of the filaments. The named individual processes were used for interpretation of the partial pressure changes in the apparatus. The significance of the above individual phenomena in the UHV experiments is pointed out in this paper.
Effect of medium on dissociation of carboxylic acids
Authors: Mollin Jiří , Pavelek Zdeněk , Navrátilová Jitka , Recmanová Alena
Published: September 2010

pK Values of carboxylic acids have been measured in mixtures water-organic solvent and confronted with the Born equation. Solubilities of benzoic acid have been measured. From the pK and solubilities found the ΔGt0(C6H5COO-) values have been calculated for various two-component solvents. The results agree with the idea that the ion transfer into another medium is affected not only by electrostatic, but also by non-electrostatic forces.
Infrared spectroscopic study of site symmetry effects for sulphite and sulphate anions in solid sodium sulphite oxidized by air oxygen
Authors: Hájek Bohumil , Muck Alexander , Šantavá Eva
Published: September 2010

The mutual replacement of SO32- and SO42- anions was studied in Na2SO3.7 H2O crystals where sulphite is slowly oxidized to sulphate by air oxygen. In a series of Na2(SO3, SO4).7 H2O samples, the C1 or Cs site symmetry appears for the SO32- anion and the site symmetry of the SO42- anion is lowered gradually from Td through D2d or C3v to C1. The replacement was also studied for anhydrous sodium sulphite obtained by dehydration or by evaporation from aqueous solution. Despite the different structures of Na2SO3 and Na2SO4 crystals (C3i1 and D2h24, respectively), the favourable dimensions of the sterically different anions allow the SO42- ions, with their own symmetry Td, to be located in the C3 sites of the SO32- ions in Na2SO3.
The influence of dispersion forces on the mercury intrusion into pores of solids
Authors: Kadlec Ondřej
Published: September 2010

On the basis of the Gibbs condition of thermodynamic equilibrium of heterogeneous system occuring in a force field, a general expression is derived for the dependence of the liquid mercury pressure on an equivalent radius of pores volume-filled on its intrusion. For the equivalent radius r of pores greater than 30 nm, this equation turns into the well-known Washburn equation. It is shown that for pores of equivalent radii smaller than 5 nm, the presence of dispersion forces is the reason of considerable deviations from the classical Washburn equation. The effect of the liquid mercury pressure on the contact angle θ of intruded mercury with pore walls is also discussed.
The application of the relaxation method in the study of electrode kinetics: Relaxation theory of the simple charge-transfer process
Authors: Kisza Adolf
Published: September 2010

The paper presents the relaxation theory of a simple charge-transfer electrode process; the derived equations provide the basic kinetic parameters. The range of applicability of the presented theory will be given in an experimental paper under preparation.
Study of the acid-base species of di-n-butyl N-(4-antipyryl)amidophosphate
Authors: Příhoda Jiří , Zeman Alois , Havel Josef
Published: September 2010

The acid-base species of di-n-butyl N-(4-antipyryl)amidophosphate present in aqueous solutions of perchloric acid were studied. The compound was observed to protonate as far as the second step in this medium, with protonation constants log βH1 = 0.49 ± 0.02 and log βH2 = -1.34 ± 0.07. The distribution of the solute between chloroform and aqueous solutions of perchloric acid was also investigated, and the value of log Kex = 2.55 was obtained.
Determination of traces of lead in tinned apple puree by liquid chromatography without sample mineralization
Authors: Vláčil František , Hamplová Věra
Published: September 2010

A method has been worked out for the direct determination of lead in apple pulp without previous sample mineralization, based on the HPLC analysis of metal diethyldithiocarbamates isolated from the apple pulp by extraction with chloroform after the addition of reagent and masking iron with KCN. The amount of lead isolated by the direct extraction is the same as that obtained by mineralization. The method suggested gives results identical with those of the standard procedure of photometric determination with dithizone after mineralization; the precision and limit of determination (0.2 ppm Pb) are also approximately the same for the two methods. The recovery in the new method is 89%, as compared with the 94% for the standard method.
Determination of 4-nitrobiphenyl and 4-aminobiphenyl by controlled-potential coulometry, differential pulse polarography and differential pulse voltammetry
Authors: Barek Jiří , Berka Antonín , Müller Marion , Zima Jiří
Published: September 2010

Conditions were sought for the determination of 4-nitrobiphenyl by controlled-potential coulometry based on its reduction on a mercury pool electrode and for its polarographic determination on a dropping mercury electrode, with detection limits of 0.7 μmol l-1 for TAST polarography and 0.06 μmol l-1 for DP polarography. The reduction of this compound on a glassy carbon electrode was employed for its determination with detection limits of 10 μmol l-1 for DC voltammetry on a rotating electrode and 1 μmol l-1 for DP voltammetry on a stationary electrode. For 4-aminobiphenyl, its oxidation on a glassy carbon electrode was employed for the determination; the detection limits were 10 μmol l-1 for DC voltammetry on a rotating electrode and 0.5 μmol l-1 for DP voltammetry on a stationary electrode.
Coke formation during the pyrolysis of hydrocarbons in the presence of sulphur compounds
Authors: Bajus Martin , Baxa Jozef
Published: September 2010

The effect of 1-butanethiol, 0,0'-di-1-butyl dithiophosphate zinc, 0,0'-diethyl dithiophosphoric acid and carbon disulphide, respectively, on the formation of coke during the pyrolysis of a reformer raffinate at 820 °C and 100 kPa was studied using a stainless steel tube flow-through reactor. The sulphur compounds were added in amounts of 0.05 to 5.0 wt.%. The coke formation was followed from the beginning of the experiment. The coking rate was lower as compared with the pyrolysis of the pure reformer raffinate; 0,0'-di-1-butyl dithiophosphate zinc, 0,0'-diethyl dithiophosphoric acid and carbon disulphide have a strong inhibiting effect on the coke formation. The coking inhibition mechanism is discussed.
Reactions of arylpropiolamides with arylacetamides
Authors: Al-Arab Mohammad M.
Published: September 2010

The reaction of 3-phenylpropiolamide with phenylacetamide yielded 2-benzyl-4-phenyl-6-pyrimidone, whilst that of o-chlorophenylpropiolamide with phenylacetamide or p-chlorophenylacetamide yielded the 4-(o-chlorophenyl)pyrimidine-2,6-dione. The reaction products were identified from their spectral analysis.
Conjugated nitroalkenes in cycloaddition reactions. Part 2. Diels–Alder reactions of E-2-aryl-1-cyano-1-nitroethenes with cyclopentadiene
Authors: Jasiński Radomir , Rzyman Michał , Barański Andrzej
Published: September 2010

The reaction between E-2-aryl-1-cyano-1-nitroethenes 1a–1e and cyclopentadiene (2) occurs according to the carbodiene [4+2]cycloaddition scheme and leads to the corresponding 6-endo-aryl-5-endo-cyano-5-exo-nitronorbornenes 3a–3e and 6-exo-aryl-5-exo-cyano-5-endo-nitronorbornenes 4a–4e as the only reaction products. The attempts to detect the products of heterodiene [4+2]cycloaddition in the reaction environment were not successful.
Incremental iodination of the eight-vertex closo monocarborane anion [closo-1-CB7H8]–: Preparation and characterization of [closo-1-CB7H5-6,7,8-I3]– and [closo-1-CB7H2-2,3,4,6,7,8-I6]–, and the synthesis of the first eight-vertex C-methylated carborane anion [1-CH3-closo-1-CB7H4-6,7,8-I3]–
Authors: Dostál Radim , Londesborough Michael G. S. , Kvíčalová Magdalena , Macháček Jan , Císařová Ivana , Janoušek Zbyněk
Published: September 2010

Iodination of [closo-1-CB7H8]–(anion1) with elemental iodine under various controlled conditions yields a continuum from mono- to hexaiodinated derivatives including the previously unknown [closo-1-CB7H5-6,7,8-I3]–(anion5) and [closo-1-CB7H2-2,3,4,6,7,8-I6]–(anion8). These species, characterized by mass spectrometry and NMR spectroscopy, and, in the case of8, by single-crystal X-ray diffraction, provide insight into the fluxional molecular behavior of anion1in solution. Investigation of direct electrophilic substitution on the carbon-vertex of anion1using standard conditions and reagents (deprotonation by BuLi followed by addition of electrophile) proved futile, but the same conditions when using the new triiodo-deravitive anion5resulted in the formation of the first eight-vertex C-methylated carborane anion [1-CH3-closo-1-CB7H4-6,7,8-I3]–(anion9), in 60% yield.
Why do patients want information if not to take part in decision making?
Authors: Manson Neil C
Published: September 2010

There is empirical evidence that many patients want information about treatment options even though they do not want to take a full part in decision-making about treatment. Such evidence may have considerable ethical implications but is methodologically problematic. It is argued here that, in fact, it is not at all surprising that patients' informational interests should be separable from (and often stronger than) their interests in decision-making. A number of different reasons for wanting information are offered, some to do with thecontentof information; some with theprocess, others with thefactoroccasionof informing. This philosophical clarification leads to some suggestions for further empirical study.
SINGLE PRODUCTION OF FOURTH FAMILY b' QUARKS AT THE LARGE HADRON ELECTRON COLLIDER
Authors: ÇAKIR O. , ÇETINKAYA V.
Published: September 2010

We examined the single production of fourth family b' quarks at the Large Hadron electron Collider (LHeC). We have analyzed the background and the signal processes for the mass range 300–700 GeV. We find the discovery region for the optimal bounds of Vqb' matrix elements.
WITTEN INDEX AND SUPERCONDUCTING STRINGS
Authors: OIKONOMOU V. K.
Published: September 2010

The Yukawa interaction sector of superstring inspired models, that give superconducting strings, can be described in terms of a supersymmetric quantum mechanics algebra. We relate the Witten index of SUSY quantum mechanics with an index characteristic to superconducting string models.
STRING THEORY AND TURBULENCE
Authors: JEJJALA VISHNU , MINIC DJORDJE , NG Y. JACK , TZE CHIA-HSIUNG
Published: September 2010

We propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov scalings in 2+1 dimensions. This string theory of turbulence should be understood in light of the AdS/CFT dictionary. Our argument is crucially based on the use of Migdal's loop variables and the self-consistent solutions of Migdal's loop equations for turbulence. In particular, there is an area law for turbulence in 2+1 dimensions related to the Kraichnan scaling.
BAGS AND CONFINEMENT GOVERNED BY SPONTANEOUS SYMMETRY BREAKING OF SCALE INVARIANCE
Authors: GUENDELMAN E. I.
Published: September 2010

A general coordinate invariant theory is constructed where confinement of gauge fields and gauge dynamics in general is governed by the spontaneous symmetry breaking (s.s.b.) of scale invariance. The model uses two measures of integration in the action, the standard [Formula: see text] where g is the determinant of the metric and another measure Φ independent of the metric. To implement scale invariance, a dilaton field is introduced. Using the first-order formalism, curvature (ΦR and [Formula: see text]) terms, gauge field term ([Formula: see text] and [Formula: see text]) and dilaton kinetic terms are introduced in a conformally invariant way. Exponential potentials for the dilaton break down (softly) the conformal invariance down to global scale invariance, which also suffers s.s.b. after integrating the equations of motion. The model has a well-defined flat space limit. As a result of the s.s.b. of scale invariance phases with different vacuum energy density appear. Inside the bags, that is in the regions of larger vacuum energy density, the gauge dynamics is normal, that is nonconfining, while for the region of smaller vacuum energy density, the gauge field dynamics is confining. Likewise, the dynamics of scalars, like would be Goldstone bosons, is suppressed inside the bags.
A SIMPLE STRATEGY FOR RENORMALIZATION: QED AT ONE-LOOP LEVEL
Authors: YANG JI-FENG , PAN ZHAO-TING
Published: September 2010

We demonstrate our simple strategy for renormalization with QED at one-loop level, basing on an elaboration of the effective field theory philosophy. No artificial regularization or deformation of the original theory is introduced here and hence no manipulation of infinities, ambiguities arise instead of infinities. Ward identities first come to reduce the number of ambiguities, the residual ones could in principle be removed by imposing physical boundary conditions. Renormalization group equations arise as "decoupling theorems" in the underlying theory perspective. In addition, a technical theorem concerning routing of external momenta is also presented and illustrated with the self-energy and vertex function as examples.
ASPECTS OF WARM-FLAT DIRECTIONS
Authors: MATSUDA TOMOHIRO
Published: September 2010

Considering the mechanism of dissipative slow-roll that has been used in warm inflation scenario, we show that dissipation may alter usual cosmological scenarios associated with SUSY-flat directions. We mainly consider SUSY-flat directions that have strong interactions with nonflat directions and may cause strong dissipation both in thermal and nonthermal backgrounds. An example is the Affleck–Dine mechanism in which dissipation may create significant (both qualitative and quantitative) discrepancies between the conventional scenario and the dissipative one. We also discuss several mechanisms of generating curvature perturbations in which the dissipative field, which is distinguished from the inflaton field, can be used as the source of cosmological perturbations. Considering the Morikawa–Sasaki dissipative coefficient, the damping caused by the dissipation may be significant for many MSSM flat directions even if the dissipation is far from thermal equilibrium.
SCHWINGER EFFECT IN NONPARALLEL D1-BRANES: A PATH INTEGRAL APPROACH
Authors: JAHAN A. , KAMANI D.
Published: September 2010

We study the Schwinger effect in a system of nonparallel D1-branes for the bosonic strings using the path integral formalism. We drive the string pair creation rate by calculating the one-loop vacuum amplitude of the setup in presence of the background electric field defined along one of the D1-branes. We find an angle dependent minimum value for the background field and show that the decaying of vacuum into string pairs takes place for the field above this value. It is shown that in [Formula: see text] limit the vacuum becomes stable and thus no pair creation occurs.
ENERGY GAP, MASS GAP, AND SPONTANEOUS SYMMETRY BREAKING
Authors: NAMBU YOICHIRO
Published: September 2010

This article is based on a talk given at a Symposium at the University of Illinois on the occasion to commemorate the 50th anniversary of BCS — I gave a historical overview of how BCS theory has come to be transplanted to particle physics and has helped solve its problems.
ANALYSIS OF FLUCTUATION CONDUCTIVITY OF GRANULAR Gd1-xPrxBa2Cu3O7-δ SUPERCONDUCTOR
Authors: LOPES CRISTIANO SANTOS , DE LEITE GUSMÃO PINHEIRO LINCOLN BRUM , DOS SANTOS MARCELO , JURELO ALCIONE ROBERTO , COSTA ROSÂNGELA MENEGOTTO , RODRIGUES PEDRO , CHINELATTO ADILSON LUIZ
Published: September 2010

Single phase polycrystalline Gd 1-x Pr x Ba 2 Cu 3 O 7-δ (0 ≤ x ≤ 0.10) samples have been prepared by standard solid state reaction technique and characterized by SEM, X-ray diffraction and electrical transport experiments. The samples were granular and homogeneous. It was observed that the critical temperature decreases and that the transition width increases with increasing Pr doping. Systematic measurements of fluctuation conductivity are reported. Special attention is taken above the critical temperature, where Gaussian and critical regimes are observed. Below the critical temperature, on approaching the zero resistance state, our results show a power-law behavior consistent with a phase transition from a paracoherent to a coherent state of the granular array.
WEAK NONLINEAR ANALYSIS OF THE NEOCLASSICAL GROWTH MODEL AT SPATIALLY HOMOGENEOUS CONDITIONS
Authors: VADASZ ALISA S. , CARSKY MILAN , GUPTHAR ABIN S. , VADASZ PETER
Published: September 2010

The neoclassical growth model is being analyzed subject to spatially homogeneous perturbations by using the weak nonlinear method of solution and comparing its results to the numerical solution. The latter expands the analytical tools beyond the investigation of Turing instability. The results identify a Hopf bifurcation at a critical value of a controlling parameter, and their comparison to direct numerical solutions show an excellent match in the neighborhood of this critical value and for amplitudes of oscillations that are not too large.
BIOMECHANICAL MODEL PREDICTING VALUES OF MUSCLE FORCES IN THE SHOULDER GIRDLE DURING ARM ELEVATION
Authors: BERTHONNAUD ERIC , MORROW MELISSA , HERZBERG GUILLAUME , AN KAI-NAN , DIMNET JOANNES
Published: September 2010

A three-dimensional (3D) geometric model for predicting muscle forces in the shoulder complex is proposed. The model was applied throughout the range of arm elevation in the scapular plan. In vitro testing has been performed on 13 cadaveric shoulders. The objectives were to determine homogeneous values of physiological parameters of shoulder muscles and to locate sites of muscular attachment to any bone of the shoulder complex. Muscular fiber lengths, lengths of contractile element (CE), and muscle volumes were measured, corresponding physiological cross-sectional area (PCSA) were calculated, and force/length muscle relations were found. An in vivo biplanar radiography was performed on five volunteers. The photogrammetric reconstruction of bone axes and landmarks were coupled with a geometric modeling of bones and muscle sites of attachment. Muscular paths were drawn and changes in lengths during movement have been estimated. Directions of muscle forces are the same as that of muscular path at the point of attachment to bone. Magnitudes of muscular forces were found from muscle lengths coupled with force/length relations. Passive forces were directly determined contrary to active muscle forces. A resulting active muscle force is calculated from balancing weight and passive forces at each articular center. Active muscle forces were calculated by distributing the resulting force among active muscles based on the muscular PCSA values.
EFFECT OF HEATED REGION ON TEMPERATURE DISTRIBUTION WITHIN TISSUE DURING MAGNETIC FLUID HYPERTHERMIA USING LATTICE BOLTZMANN METHOD
Authors: GOLNESHAN ALI AKBAR , LAHONIAN MANSOUR
Published: September 2010

This work uses the lattice Boltzmann model (LBM) to solve the Pennes bio-heat equation (BHE) to predict the temperature rise behavior occurring in cylindrical biological tissues during magnetic fluid hyperthermia (MFH). Therefore, LBM is extended to solve the bio-heat transfer problem with curved boundary conditions. Effect of magnetic nanoparticles' (MNPs) volume fraction as well as the vastness of heated region on the temperature distribution are shown. The analytical and numerical finite difference solutions reveal the accuracy of the model.
The biostratigraphical distribution of earliest tetrapods (Late Devonian): a revised version with comments on biodiversification
Authors: Blieck A. , Clément G. , Streel M.
Published: September 2010

The 13 presently known genera of Late Devonian tetrapods are situated in the recently completed miospore zonation of Western Gondwana and Euramerica, in relation to the standard conodont zonation. Some of them are still unprecisely dated. The stratigraphic sequences of East Greenland, North China and East Australia are briefly reviewed to discuss the age of the tetrapods collected there and to analyse consequences in relation to the Frasnian–Famennian and Devonian–Carboniferous boundaries. Two episodes of biodiversification seem to have occurred: the first in the Frasnian and the second in the late and latest Famennian. Due to the currently known fossil evidence, the consensus scenario advocates a late Middle Devonian to early Late Devonian origin of tetrapods on the Old Red Sandstone Continent (Euramerica) at a time of warm climate and recovering atmospheric oxygen level during the building of a pre-Pangaean configuration of landmasses.
Osmotic tolerance and habitat of early stegocephalians: indirect evidence from parsimony, taphonomy, palaeobiogeography, physiology and morphology
Authors: Laurin M. , Soler-Gijón R.
Published: September 2010

There are probably many reasons for the widespread belief that temnospondyls and other early stegocephalians were largely restricted to freshwater, but three of the contributing factors will be discussed below. First, temnospondyls have been called amphibians (and thought to be more closely related to extant amphibians than to amniotes). Some authors may have simply concluded that, like extant amphibians, temnospondyls could not live in oceans and seas. Second, under some phylogenies, temnospondyls are more closely related to anurans (and possibly urodeles) than to gymnophionans and could be expected, for parsimony reasons, to share the intolerance of all extant amphibians to saltwater. Similarly, ‘lepospondyls’ are often thought to be more closely related to gymnophionans than to anurans, and could also be expected to lack saltwater tolerance. Third, extant lungfishes live exclusively in freshwater, and early sarcopterygians have long been thought to share this habitat. These interpretations probably explain the widespread belief that early amphibians and early stem-tetrapods were largely restricted to freshwater. However, these three interpretations have been refuted or questioned by recent investigations. A review of the evidence suggests that several (perhaps most) early stegocephalians tolerated saltwater, even although they also lived in freshwater.
Palaeogeographic and palaeoclimatic considerations based on Ordovician to Lochkovian vegetation
Authors: Steemans Philippe , Wellman Charles H. , Gerrienne Philippe
Published: September 2010

This paper summarizes research on Ordovician to Lochkovian vegetation development in a palaeogeographic framework. A terrestrialization model is described. Palaeogeographic maps are modified to explain the vegetation migrations. Land plants first evolved on the Gondwana plate and colonized Avalonia and later Laurentia and Baltica when those plates were in close proximity (Ashgill–Llandovery). South America was colonized during the Llandovery following the collapse of the ice sheet centred on the southern pole which had previously been an impassable barrier for miospores. An Aeronian–Telychian event related to the global early Silurian transgression modified the vegetation by destroying biotopes where the earliest vegetation was thriving. During the regression, trilete spore-producing plants appear to have been more able to respond to environmental changes and dominated the vegetation from the Homerian. Cryptospore-producing plants could survive under a wide range of climates, which helped them to survive during the Hirnantian glaciation. On the contrary, the earliest trilete spore-producing plants were probably climatically restricted, as suggested by latitudinal variation in assemblage composition. By the end of the Silurian, there were several phytogeographic units. Information on the earliest vegetation favours palaeogeographic reconstructions where plates are in close proximity.
First record of
Rellimia
Leclercq & Bonamo (Aneurophytales) from Gondwana, with comments on the earliest lignophytes
Authors: Gerrienne P. , Meyer-Berthaud B. , Lardeux H. , Régnault S.
Published: September 2010

The lignophytes (Embryophytes that possess a bifacial cambium) evolved during the Devonian period and include seed plants. Their advent was a major event in the history of life and had a profound impact on terrestrial environments. Recent reinvestigations of a Devonian locality, Dechra Aït Abdallah in Central Morocco, led to the discovery of a rich assemblage of fossil plants and Tentaculita. This paper focuses on a single specimen of the lignophyte
Rellimia
Leclercq & Bonamo.
Rellimia
(Aneurophytales) is a monospecific genus reported from a large number of Middle Devonian localities from western Europe (Belgium, Czech Republic, Germany and Scotland) and America. Its fertile organs are highly distinctive and borne helically on branches. They consist of a basal stalk that dichotomizes once near the base, the resulting branches dividing pinnately and bearing elongated sporangia terminally on ultimate divisions. According to the late Emsian age indicated by our sample of Tentaculita, this Moroccan specimen is to date the earliest representative of both the genus and the lignophytes. If confirmed, this occurrence suggests a possible origin of the Aneurophytalean lignophytes in Gondwana and their rapid and widespread colonization in the Middle Devonian towards Laurussia.
Genetic Diversity among Offspring from Archived Salmonella enterica ssp. enterica Serovar Typhimurium (Demerec Collection): In Search of Survival Strategies
Authors: Eisenstark Abraham
Published: September 2010

Extensive phenotypic and genomic diversity was detected among offspring of Salmonella enterica ssp. enterica serovar Typhimurium LT2 (nonmutator) and LT7 (mutator, mutL) strains after decades of storage in sealed nutrient agar stabs. In addition to numerous losses in carbon and nitrogen metabolism, the acquired new metabolites indicated that alternate pathways were established. Particularly striking was the array of phage types when this phenotype was expected to be a stable feature. Evidence is presented regarding the role of mutator gene mutL− in the establishment of diversity as well as the ability of cells to return to mutL+ genetic stabilization. Mutations included deletions, duplications, frameshifts, inversions and transpositions. In competition tests, survivors were more fit than were wild type. Because survival strategies continue to intrigue microbiologists, observations are compared with those of others who have addressed related questions. A brief genealogy of the archived strains is also recorded.
Bacterial Microcompartments
Authors: Kerfeld Cheryl A. , Heinhorst Sabine , Cannon Gordon C.
Published: September 2010

Bacterial microcompartments (BMCs) are organelles composed entirely of protein. They promote specific metabolic processes by encapsulating and colocalizing enzymes with their substrates and cofactors, by protecting vulnerable enzymes in a defined microenvironment, and by sequestering toxic or volatile intermediates. Prototypes of the BMCs are the carboxysomes of autotrophic bacteria. However, structures of similar polyhedral shape are being discovered in an ever-increasing number of heterotrophic bacteria, where they participate in the utilization of specialty carbon and energy sources. Comparative genomics reveals that the potential for this type of compartmentalization is widespread across bacterial phyla and suggests that genetic modules encoding BMCs are frequently laterally transferred among bacteria. The diverse functions of these BMCs suggest that they contribute to metabolic innovation in bacteria in a broad range of environments.
Intracellular Lifestyles and Immune Evasion Strategies of UropathogenicEscherichia coli
Authors: Hunstad David A. , Justice Sheryl S.
Published: September 2010

Paradigms in the pathogenesis of urinary tract infections have shifted dramatically as a result of recent scientific revelations. Beyond extracellular colonization of the bladder luminal surface, as traditional clinical thinking would hold, uropathogenic bacteria direct a complex, intracellular cascade that shelters bacteria from host defenses and leads to persistent bacterial residence within the epithelium. After epithelial invasion, many organisms are promptly expelled by bladder epithelial cells; a minority establish a niche in the cytoplasm that results in the development of biofilm-like intracellular bacterial communities and serves as the primary location for bacterial expansion. Exfoliation of the superficial epithelial layer acts to reduce the bacterial load but facilitates chronic residence of small nests of bacteria that later reemerge to cause some episodes of recurrent cystitis, a familiar clinical scenario in otherwise healthy women. Advances in both in vitro and animal models of cystitis promise to provide insights into the bacterial and host transcriptional and biochemical pathways that define these pathogenic stages.
Disruption of PICK1 attenuates the function of ASICs and PKC regulation of ASICs
Authors: Hu Zhuang-Li , Huang Chao , Fu Hui , Jin You , Wu Wen-Ning , Xiong Qiu-Ju , Xie Na , Long Li-Hong , Chen Jian-Guo , Wang Fang
Published: September 2010

Acid-sensing ion channels (ASICs) extensively exist in both central and peripheral neuronal systems and contribute to many physiological and pathological processes. The protein that interacts with C kinase 1 (PICK1) was cloned as one of the proteins interacting with protein kinase C (PKC) and colocalized with ASIC1 and ASIC2. Here, we used PICK1 knockout (PICK1-KO) C57/BL6 mice together with the whole cell patch clamp, calcium imaging, RT-PCR, Western blot, and immunocytochemistry techniques to explore the possible change in ASICs and the regulatory effects of PKC on ASICs. The results showed that PICK1 played a key role in regulation of ASIC functions. In PICK1-KO mouse cortical neurons, both the amplitude of ASIC currents and elevation of [Ca2+]i mediated by acid were decreased, which were attributable to the decreased expression of ASIC1a and ASIC2a proteins in the plasma membrane. PKC, a partner protein of PICK1, regulated ASIC functions via PICK1. The agonist and antagonist of PKC only altered ASIC currents and acid-induced increase in [Ca2+]i in wild-type, but not in KO mice. In conclusion, our data provided the direct evidence from PICK1-KO mice that a novel target protein, PICK1, would regulate ASIC function and membrane expression in the brain. In addition, PICK1 played the bridge role between PKC and ASICs.
Sleep pattern in an experimental model of chronic kidney disease
Authors: Hirotsu Camila , Tufik Sergio , Bergamaschi Cassia Toledo , Tenorio Neuli Maria , Araujo Paula , Andersen Monica Levy
Published: September 2010

The prevalence of sleep disorders is significantly elevated in chronic kidney disease (CKD) patients. Numerous factors likely contribute to the high prevalence of sleep problems in uremic patients. The objective of this study was to evaluate the long-term sleep pattern changes in uremic rats during disease progression. Sleep recordings of the rats were monitored during light and dark periods that lasted 12 h each. These recordings were performed on days 7, 30, 60, and 90 after CKD induction. Cardiovascular, hormonal, and biochemical changes were evaluated at these same time points in control and uremic rats. CKD progression was reflected by the presence of hypertension and progressive increases in urea, creatinine, and cholesterol levels. We also observed hormonal fluctuations of corticosterone and ACTH, which indicated a potential alteration in the hypothalamic-pituitary-adrenal axis in diseased rats. In addition, rats with CKD demonstrated fragmented sleep with a greater number of arousals and decreased sleep efficiency in the light period during disease progression. In the dark period, there was an initial increase in sleep efficiency in CKD rats, but after 90 days of CKD, these animals slept less compared with the control group. Collectively, these metabolic and cardiovascular changes were associated with the persistent alterations in sleep architecture observed in CKD rats.
Darbepoetin-α treatment enhances glomerular regenerative process in the Thy-1 glomerulonephritis model
Authors: Cañadillas Sagrario , Ortega Rosa , Estepa Jose-Carlos , Egea Jeronimo , Gonzalez-Menchen Alberto , Perez-Seoane Carlos , Lopez-Andreu Maria , Ramirez Rafael , Tetta Ciro , Rodriguez Mariano , Martin-Malo Alejandro , Aljama Pedro
Published: September 2010

Recent studies have demonstrated that erythropoietin (EPO) and its analogs induce cytoprotective effects on many nonerythroid cells. In this study, we examined whether darbepoetin-α might prevent glomerular lesions in the Thy-1.1 model of glomerulonephritis (Thy-1-GN). GN was induced in Wistar rats by a single injection of monoclonal anti-Thy-1.1 antibody. Rats were killed at 24 h, 72 h, 7 days, 10 days, or 15 days after antibody injection. Kidneys were removed for histological analysis, and proteinuria was measured. Because at day 7 the maximal degree of renal damage and proteinuria was found, the effect of darbepoetin-α was tested at day 7 and two different protocols of administration were used; After anti-Thy-1.1 injection, rats received two doses of darbepoetin-α or vehicle at days 0 and 4 or at days 4 and 6. At day 7, proteinuria, plasma creatinine concentration, and renal morphology analysis were performed. Also, α-actin, desmin, caspase-3, and Ki67 protein expression were evaluated by immunohistochemistry. Our results showed that in both protocols of administration, darbepoetin-α treatment decreased proteinuria in Thy-1-GN rats and this effect correlated with the improvement in renal morphology. Glomerular lesions, α-actin, and caspase-3 protein expression, observed in most glomeruli of Thy-1-GN rats, were significantly reduced in darbepoetin-α-treated rats, while cell proliferation was significantly enhanced. The results indicate that darbepoetin-α treatment promotes glomerular recovery.
Connecting tubule glomerular feedback antagonizes tubuloglomerular feedback in vivo
Authors: Wang H. , Garvin J. L. , D'Ambrosio M. A. , Ren Y. , Carretero O. A.
Published: September 2010

In vitro experiments showed that the connecting tubule (CNT) sends a signal that dilates the afferent arteriole (Af-Art) when Na+reabsorption in the CNT lumen increases. We call this process CNT glomerular feedback (CTGF) to differentiate it from tubuloglomerular feedback (TGF), which is a cross talk between the macula densa (MD) and the Af-Art. In TGF, the MD signals the Af-Art to constrict when NaCl transport by the MD is enhanced by increased luminal NaCl. CTGF is mediated by CNT Na+transport via epithelial Na+channels (ENaC). However, we do not know whether CTGF occurs in vivo or whether it opposes the increase in Af-Art resistance caused by TGF. We hypothesized that CTGF occurs in vivo and opposes TGF. To test our hypothesis, we conducted in vivo micropuncture of individual rat nephrons, measuring stop-flow pressure (PSF) as an index of glomerular filtration pressure. To test whether activation of CTGF opposes TGF, we used benzamil to block CNT Na+transport and thus CTGF. CTGF inhibition with the ENaC blocker benzamil (1 μM) potentiated the decrease in PSFat 40 and 80 nl/min. Next, we tested whether we could augment CTGF by inhibiting NaCl reabsorption in the distal convoluted tubule with hydrochlorothiazide (HCTZ, 1 mM) to enhance NaCl delivery to the CNT. In the presence of HCTZ, benzamil potentiated the decrease in PSFat 20, 40, and 80 nl/min. We concluded that in vivo CTGF occurs and opposes the vasoconstrictor effect of TGF.
Power loss is greater in old men than young men during fast plantar flexion contractions
Authors: Dalton Brian H. , Power Geoffrey A. , Vandervoort Anthony A. , Rice Charles L.
Published: September 2010

It is unclear during human aging whether healthy older adults (>70 yr old) experience greater, lesser, or the same fatigability compared with younger adults. The reported disparate findings may be related to the task-dependent nature of fatigue and the limited number of studies exploring nonisometric contractile function and aging. The purpose here was to determine the effects of fast shortening contractions on the fatigability of the triceps surae in 10 young (∼24 yr old) and 10 old (∼78 yr old) men using isometric and dynamic measures. Participants performed 50 maximal velocity-dependent plantar flexions at a constant load of 20% maximal voluntary isometric contraction (MVC). Isometric twitch properties and MVCs were tested at baseline and during and following the fatigue task. Voluntary activation was similar between the old and young (∼98%) and was unaltered with fatigue. The old had 26% lower ( P < 0.01) isometric MVC torque and 18% slower ( P < 0.01) maximal shortening velocity than the young. Hence, peak power was 38% lower in the old ( P < 0.01). At task termination, MVC torque was maintained in the old ( P = 0.15) but decreased by 21% in the young ( P < 0.01). Twitch half-relaxation time was lengthened in the old at task termination by 26% ( P < 0.01) but unchanged in the young ( P = 0.10). Peak power was reduced by 24% and 17% at task termination in the old and young, respectively ( P < 0.01). Despite a better maintenance in isometric MVC torque production, the weaker and slower contracting triceps surae of the old was more fatigable than the young during fast dynamic efforts with an unconstrained velocity.
Reduction in tendon elasticity from unloading is unrelated to its hypertrophy
Authors: Kinugasa Ryuta , Hodgson John A. , Edgerton V. Reggie , Shin David D. , Sinha Shantanu
Published: September 2010

Tendinous tissues respond to chronic unloading with adaptive changes in mechanical, elastic, and morphological properties. However, little is known about the changes in the detailed structures of the entire tendinous tissue and whether the change in tendon stiffness is related to morphology. We investigated changes in dimensional (volume, cross-sectional area, segmented lengths) and elastic (Young's modulus) properties of the Achilles tendon and distal aponeurosis in response to chronic unilateral lower limb suspension (ULLS) using velocity encoded phase contrast (VE-PC) and three-dimensional morphometric magnetic resonance imaging (MRI). Five healthy subjects underwent ULLS for 4 wk. Axial morphometric MRI was acquired along the entire length from the calcaneous to the medial gastrocnemius insertion. An oblique sagittal VE-PC MRI was also acquired. The Young's modulus could be calculated from this cine dynamic sequence of velocity encoded images from the slope of the stress-strain curve during the submaximal isometric plantar flexion. After 4 wk of ULLS, we found significant (46.7%) decrease in maximum plantar flexion torque. The total volumes of entire tendinous tissue (determined as the sum of the Achilles tendon and distal aponeurosis) increased significantly by 6.4% (11.9 vs. 12.7 ml) after ULLS. In contrast, Young's modulus decreased significantly by 10.4% (211.7 vs. 189.6 MPa) for the Achilles tendon and 29.0% for the distal aponeurosis (158.8 vs. 113.0 MPa) following ULLS. There was no significant correlation between relative change in volume and Young's modulus with 4 wk of ULLS. It is suggested that, although tendon hypertrophy can be expected to adversely affect tendon stiffness, the absence of any significant correlation between the magnitude of tendon hypertrophy and reduced Young's modulus indicates that dimensional factors were not critical to the elastic properties.
Motor unit behavior during submaximal contractions following six weeks of either endurance or strength training
Authors: Vila-Chã Carolina , Falla Deborah , Farina Dario
Published: September 2010

The study investigated changes in motor output and motor unit behavior following 6 wk of either strength or endurance training programs commonly used in conditioning and rehabilitation. Twenty-seven sedentary healthy men (age, 26.1 ± 3.9 yr; mean ± SD) were randomly assigned to strength training (ST; n = 9), endurance training (ET; n = 10), or a control group (CT; n = 8). Maximum voluntary contraction (MVC), time to task failure (isometric contraction at 30% MVC), and rate of force development (RFD) of the quadriceps were measured before ( week 0), during ( week 3), and after a training program of 6 wk. In each experimental session, surface and intramuscular EMG signals were recorded from the vastus medialis obliquus and vastus lateralis muscles during isometric knee extension at 10 and 30% MVC. After 6 wk of training, MVC and RFD increased in the ST group (17.5 ± 7.5 and 33.3 ± 15.9%, respectively; P < 0.05), whereas time to task failure was prolonged in the ET group (29.7 ± 13.4%; P < 0.05). The surface EMG amplitude at 30% MVC force increased with training in both groups, but the training-induced changes in motor unit discharge rates differed between groups. After endurance training, the motor unit discharge rate at 30% MVC decreased from 11.3 ± 1.3 to 10.1 ± 1.1 pulses per second (pps; P < 0.05) in the vasti muscles, whereas after strength training it increased from 11.4 ± 1.2 to 12.7 ± 1.3 pps ( P < 0.05). Finally, motor unit conduction velocity during the contractions at 30% MVC increased for both the ST and ET groups, but only after 6 wk of training ( P < 0.05). In conclusion, these strength and endurance training programs elicit opposite adjustments in motor unit discharge rates but similar changes in muscle fiber conduction velocity.
Evoked Potentials in Motor Cortical Local Field Potentials Reflect Task Timing and Behavioral Performance
Authors: Kilavik Bjørg Elisabeth , Confais Joachim , Ponce-Alvarez Adrián , Diesmann Markus , Riehle Alexa
Published: September 2010

Evoked potentials (EPs) are observed in motor cortical local field potentials (LFPs) during movement execution (movement-related potentials [MRPs]) and in response to relevant visual cues (visual evoked potentials [VEPs]). Motor cortical EPs may be directionally selective, but little is known concerning their relation to other aspects of motor behavior, such as task timing and performance. We recorded LFPs in motor cortex of two monkeys during performance of a precued arm-reaching task. A time cue at the start of each trial signaled delay duration and thereby the pace of the task and the available time for movement preparation. VEPs and MRPs were strongly modulated by the delay duration, VEPs being systematically larger in short-delay trials and MRPs larger in long-delay trials. Despite these systematic modulations related to the task timing, directional selectivity was similar in short and long trials. The behavioral reaction time was positively correlated with MRP size and negatively correlated with VEP size, within sessions. In addition, the behavioral performance improved across sessions, in parallel with a slow decrease in the size of VEPs and MRPs. Our results clearly show the strong influence of the behavioral context and performance on motor cortical population activity during movement preparation and execution.
Regulation of Inhibitory Synapses by Presynaptic D4Dopamine Receptors in Thalamus
Authors: Govindaiah Gubbi , Wang Tongfei , Gillette Martha U. , Crandall Shane R. , Cox Charles L.
Published: September 2010

Dopamine (DA) receptors are the principal targets of drugs used in the treatment of schizophrenia. Among the five DA receptor subtypes, the D4subtype is of particular interest because of the relatively high affinity of the atypical neuropleptic clozapine for D4compared with D2receptors. GABA-containing neurons in the thalamic reticular nucleus (TRN) and globus pallidus (GP) express D4receptors. TRN neurons receive GABAergic afferents from globus pallidus (GP), substantia nigra pars reticulata (SNr), and basal forebrain as well as neighboring TRN neuron collaterals. In addition, TRN receives dopaminergic innervations from substantia nigra pars compacta (SNc); however, the role of D4receptors in neuronal signaling at inhibitory synapses is unknown. Using whole cell recordings from in vitro pallido-thalamic slices, we demonstrate that DA selectively suppresses GABAAreceptor-mediated inhibitory postsynaptic currents (IPSCs) evoked by GP stimulation. The D2-like receptor (D2,3,4) agonist, quinpirole, and selective D4receptor agonist, PD168077, mimicked the actions of DA. The suppressive actions of DA and its agonists were associated with alterations in paired pulse ratio and a decrease in the frequency of miniature IPSCs, suggesting a presynaptic site of action. GABAAreceptor agonist, muscimol, induced postsynaptic currents in TRN neurons were unaltered by DA or quinpirole, consistent with the presynaptic site of action. Finally, DA agonists did not alter intra-TRN inhibitory signaling. Our data demonstrate that the activation of presynaptic D4receptors regulates GABA release from GP efferents but not TRN collaterals. This novel and selective action of D4receptor activation on GP-mediated inhibition may provide insight to potential functional significance of atypical antipsychotic agents. These findings suggest a potential heightened TRN neuron activity in certain neurological conditions, such as schizophrenia and attention deficit hyperactive disorders.