bluuebunny/crossref_metadata_2025 huggingface dataset:
Stimulation of adventitious rooting in sunflower (Helianthus annuus) by low pH: possible role of auxin
Authors: Liu Jin-Hao , Mukherjee Ilabanta , Reid David M.
Published: April 2008

Adventitious root formation by the hypocotyl cuttings of sunflower seedlings was greatly affected by the pH of buffered and unbuffered solutions bathing their basal portion. Exposure to low pH for 5 h after original root excision promoted root formation. Reduction of endogenous indole-3-acetic acid movement from the cotyledons and shoot apex was achieved by using N-1-naphthylphthalamic acid (an inhibitor of indole-3-acetic acid transport) and by removal of the cotyledons and shoot apex. Both the inhibitor and organ removal inhibited adventitious root formation, but acidic conditions could, to varying degrees, overcome this inhibition. Acidic conditions also increased the rate of [3H]indole-3-acetic acid uptake from the solutions around the hypocotyl bases and the rate of [3H]indole-3-acetic acid movement from cotyledons to the hypocotyl bases. Thus, acidic conditions may stimulate rooting by increasing the rate of basipetal indole-3-acetic acid transport to the zone of root initiation. These experiments show that in studies of the effects of various substances on rooting, the experimenter must be aware of these pH effects and take appropriate precautions. Key words: adventitious roots, auxin, indole-3-acetic acid, Helianthus annuus, pH.
Ultrastructure of spermatia and spermatium ontogeny in the rust fungus Cronartium quercuum f.sp. fusiforme
Authors: Mims C. W. , Doudrick R. L.
Published: April 2008

Spermogonia of Cronartium quercuum f.sp. fusiforme developed just beneath the bark on galled regions of infected pine seedlings. Spermogonia consist of flattened, spreading, island-like masses of fungal tissue covered with a thin layer of liquid containing large numbers of spermatia. Spermatia arose in an annellophoric fashion from the tips of long, slender sporogenous cells produced in a distinct layer. Each sporogenous cell contained a large prominent nucleus that underwent mitosis as each spermatium initial developed. One of the resulting nuclei moved into the initial while the other remained in the sporogenous cell. Once a spermatium was delimited, it was pushed away from the tip of the sporogenous cell as another spermatium initial developed below it. Once delimited, a spermatium underwent specific morphological changes as it matured. A mature spermatium was subpyriform in shape and surrounded by a thin wall. In addition to a single large nucleus each spermatium contained ribosomes, mitochondria, lipid bodies, strands of endoplasmic reticulum, vacuole-like inclusions, and many small vesicles that packed its base. Keywords: transmission electron microscopy, pycnidia, pycnidiospores, spermogonia.
Effet de la température sur l'installation et la croissance des plantes annuelles de marais temporaires méditerranéens
Authors: Bonis A. , Lepart J. , Bonis A. , Laloé F.
Published: April 2008

The abundance of annual plants in temporary marshes is subjected to strong fluctuations through time. Such fluctuations could be linked with the variability of the Mediterranean climate. We studied experimentally the relationships between those fluctuations of abundance and the water temperature. The establishment and growth pattern of the species were studied in three temperate ranges. Each species has its own germination pattern, which varies with the temperature. The speed of seedling emergence changes with the temperature for all species. The germination rate is modified significantly only for charophytes, with a strong decrease under cold conditions. The size of the diaspore bank explains a large part of the germination dynamics for Chara sp. and Zannichellia spp. At the end of the establishment stage, the cover is maximum under warm conditions and Callitriche truncata and Zannichellia spp. have the largest cover values. At the end of the growth period, Ranunculus baudotii generally dominates the community in terms of biomass, whereas C. truncata is dominated. Species biomass varies with the temperature during the establishment or (and) the growth stage, except for Zannichellia spp. There is no obvious "preemption" effect: the contrasted life history strategies among species allow dominance relationship modifications during the life cycle. Keywords: macrophytes, germination dynamics, water regime, "preemption".
Scope of improvement of treatment capacity of activated sludge process by hybrid modification
Authors: Hait Subrata , Mazumder Debabrata
Published: April 2008

Activated sludge process is widely used for wastewater treatment throughout the world with various needful modifications. The hybrid modification of conventional activated sludge process utilizes a suspended media of appropriate inert material or fixed surface that serves as carrier material for growing active microorganisms on its surface. As a result the carrier media allows the biological reactor to operate at a higher biomass concentration, compared to the conventional activated sludge process. The hybrid modification of conventional activated sludge process can be configured either to provide additional capacity for biochemical oxygen demand (BOD) removal or to facilitate nitrogen control. The process is ideally suited for upgrading the existing system with a nominal modification. The present paper summarizes various research work towards the hybrid system to review the requirements and scope of modification, development and evolution of the hybrid modification. The review concludes with an assessment of financial viability of hybrid modifications.
Exposure times and energy densities for ultrasonic disinfection of Escherichia coli, Pseudomonas aeruginosa, Enterococcus avium, and sewage
Authors: Stamper David M. , Holm Eric R. , Brizzolara Robert A.
Published: April 2008

We investigated the disinfection of sewage and several bacterial pure cultures relevant to sewage using ultrasound produced by the magnetostrictive material, TERFENOL-D. Particular attention was paid to measuring the ultrasonic exposure time and energy density required to kill bacteria. Ultrasonic power was measured and recorded during the treatments, and bacterial kill curves were constructed based on both exposure time and total energy. In 100 mL of synthetic graywater medium, bacterial pure cultures required from ~5 to 16 min per log kill at moderate intensity (~25 W·cm–2), while a sewage sample took several times longer to experience a 90% kill. The effects of intensity, horn size, sonication medium, and vessel geometry and volume on exposure time and energy density were explored. Intensity, horn size, and the sonication medium had significant effects on bacterial kill by ultrasound, but vessel geometry did not. The volume of the liquid being treated and the treatment time were correlated, indicating that the volume of the disinfection zone was smaller than the volume of the liquid being treated.
Properties of a non collagen-degradingBacillus subtiliskeratinase
Authors: Macedo Alexandre José , Beys da Silva Walter Orlando , Termignoni Carlos
Published: April 2008

Bacillus subtilis S14 produces a keratinase (KerS14) with non collagen-degrading activity. Indeed, this is the first keratinase described so far that does not have any detectable effect on collagen, which is a crucial property for an enzyme intended to be used in skin dehairing. Because of its importance as an industrial tanning enzyme, we report the biochemical characterization of KerS14. This protein exhibited an apparent molecular mass of 27 kDa, a pI of 6.5, and an optimum pH in the range of 8.0–9.0. The enzyme’s activity was stimulated by Mn2+(7.7-fold), Ca2+(6.1-fold), Mg2+(4.9-fold), and Co2+(4.0-fold) but was inhibited by Cu2+and Zn2+. Using p-nitroanilide and methylcoumarine derivatized peptides, we observed that KerS14 prefered Arg at subsite P1, small amino acid residues at subsite P2, and Gln or Glu at subsite P3. KerS14 presented higher keratin degradation specificity than other commercial proteases. Its high keratinolytic activity and the absence of virtually any activity against collagen remark the biotechnological potential of this enzyme to be used at larger scales in tannery dehairing processes.
Recovery of useful traits from isolates inhabiting an agricultural soil cultivated with herbicide-resistant poplars
Authors: Balestrazzi Alma , Bonadei Martina , Zelasco Samanta , Quattrini Emanuele , Calvio Cinzia , Galizzi Alessandro , Carbonera Daniela
Published: April 2008

The aim of this study was to investigate the culturable bacteria living in soil cultivated with Basta®-tolerant transgenic white poplars ( Populus alba L. ‘Villafranca’). Plate Count Agar medium containing phosphinothricin, the active component of Basta®, was used to isolate the herbicide-resistant bacteria (HRB). No significant changes in the size of the soil microbial flora following herbicide treatment were observed. The characterization of HRB isolates by 16S rDNA-based taxonomy revealed a predominance of Pseudomonas and Bacillus species. The screening carried out on soil samples allowed for the recovery of isolates with useful properties for biotechnological and agronomical purposes, particularly in relation to root development. Among the tested isolates, only HRB-1b, HRB-1c, and HRB-7 showed remarkable swarming ability, a valuable trait supporting the beneficial plant–microbe interactions. HRB-1c was also characterized by consistent production of indoleacetic acid (17.8 ± 0.09 μg·mL–1· (OD600unit)–1), and it was able to stimulate the in vitro growth of Villafranca explants. Since novel tools are constantly required to enhance productivity of perennial species and to expand their use for practical purposes, the availability of bacteria that support tree growth, such as the HRB-1c isolate, represents a significant advantage.
COST ANALYSIS OF THE R-UNRELIABLE-UNLOADER QUEUEING SYSTEM
Authors: WANG KUO-HSIUNG , OH CHUN-CHIN , KE JAU-CHUAN
Published: April 2008

This paper analyzes the unloader queueing model in which N identical trailers are unloaded by R unreliable unloaders. Steady-state analytic solutions are obtained with the assumptions that trip times, unloading times, finishing times, breakdown times, and repair times have exponential distributions. A cost model is developed to determine the optimal values of the number of unloaders and the finishing rate simultaneously, in order to minimize the expected cost per unit time. Numerical results are provided in which several steady-state characteristics of the system are calculated based on assumed numerical values given to the system parameters and the cost elements. Sensitivity analysis is also studied.
ANALYSIS OF VISCOELASTICITY OF HUMAN SKIN FOR PREVENTION OF PRESSURE ULCERS
Authors: AKIYAMA YOKO , YAMAMOTO YOSHIRO , DOI YUSUKE , IZUMI YOSHINOBU , NISHIJIMA SHIGEHIRO , KIMURA HIROKAZU
Published: April 2008

Change in viscoelasticity of human skin with aging is evaluated by measurement of deformation under suction and of resonance frequency change under probe indentation. The elastic modulus of human skin measured by suction increases with aging, but that measured by resonance frequency change decreases; the difference is considered to be caused by the difference in measured depth region of the human skin. In order to clarify the depth region which can be measured by each technique, strain distribution is calculated by the finite element method (FEM). The results show that the epidermis is mainly deformed by the skin suction method, whereas the dermis and subcutaneous tissue are mainly deformed by measurement of resonance frequency change. For confirmation of FEM results, skin models made of silicone rubber are prepared and measured by the two methods. Viscoelasticity in the depth region from the surface to several hundred micrometers of the material is obtained by the skin suction method, while that in the region from several millimeters to several centimeters is obtained by the resonance frequency change. Based on these results, it is observed that the elastic modulus of epidermis tends to increase with aging while that of dermis and subcutaneous tissue tends to decrease, thus causing pressure ulcers.
AORTOVENTRICULAR MECHANICAL MATCHING: SIMULATION OF NORMAL AND PATHOLOGICAL CONDITIONS
Authors: ZANNOLI ROMANO , CORAZZA IVAN , BRANZI ANGELO , ROSSI PIER LUCA
Published: April 2008

A mechanical mock of the cardiovascular system was used to simulate different conditions of ventricular-arterial mechanical matching. Four ventricles and four aortas with different elastances were set up, and all possible connection combinations tested by sampling ventricular and aortic pressures and flows. The mechanical energy produced by the simulated ventricles and the amount transferred to the aorta in the different connection conditions were calculated. The results demonstrate a clear dependence between the mechanical work production of the ventricles and the ventricular elastance (slope of the end-systolic pressure–volume relation) (from 20.42 ± 0.02 mJ/beat to 12.10 ± 0.02 mJ/beat), and an efficiency of energy transfer to the aorta strongly dependent on ventricular-aortic mechanical matching (from 56% to 20.7%). These results show that, even in optimal simulated conditions, only 56% of the energy produced is transferred to the load; and highlight the important role of mechanical aspects in conditions of very limited cardiovascular performance (i.e. final stages of heart failure), where energy transfer efficiency may be as low as 20.7%. This evidence emphasizes that the mechanical aspects must also be entertained in the evolution of complex cardiovascular pathologies, evaluating the possibility of combining mechanical and pharmaceutical interventions.
STUDY OF HUMAN THERMOREGULATION: ADAPTIVE OPTIMIZATION CONTROL THEORY ANALYSIS
Authors: NG E. Y. K. , LIM L. W.
Published: April 2008

An example of homeostasis is temperature regulation at a desired level; this physiological process leads to the preservation of a stable biological environment. A control-theory–based model permits a biomedical engineer to understand the complex operation of thermoregulation, by converting general information to knowledge, and can be integrated to see how systemic parameters influence the entire system. The thermal inputs organized in the hypothalamus to activate thermoregulation responses to heat and cold stimuli, with the widely accepted set-point hypothesis for the regulation of body temperature from a control systems point of view, are, however, not entirely known. There are circumstances (e.g. fever) in which the presumed set-point mechanism appears to break down. This paper evaluates a novel set-level adaptive optimal thermal control paradigm inspired by Hebbian covariance synaptic adaptation, previously proposed based on its potential to predict the homeostatic respiratory system. It introduces a Hebbian feedback covariance learning (HFCL) concept in order to align a neuronal network into the analysis of the thermoregulation system. Hebbian theory is concerned with how neurons connect among themselves to become engrams. The passive-active mathematical model for simulating human thermoregulation during exercise was compared in cool, warm, and hot environments, and then was translated into MATLAB to predict thermoregulation. The two-node core and shell model predictions are comparable with observed thermoregulation responses from the existing literature. The thermoregulation changes with respect to proportionality constant and sensitivity of the receptors. A reasonably general agreement with the measured mean group data of earlier performed laboratory exercise studies was obtained for peak temperature, although it tended to overpredict the core body temperature.
GAUGE THEORIES OF GRAVITY AND MASS GENERATION
Authors: ALDAYA V. , SÁNCHEZ-SASTRE E.
Published: April 2008

The compensating Utiyama's method including space-time symmetries is revisited as well as the gauge gravitational theories associated with translation, Poincaré and Weyl groups. Then we propose an extension of the gauge symmetry, allowing for the incorporation of the gauge group parameters into the theory as dynamical fields by considering the jet-gauge group as fundamental symmetry. As a consequence, a natural mass-generating mechanism for the gauge potentials arises without damaging gauge invariance. We also present, as a simple example, some sort of generalized Stueckelberg model for the Weyl group, thus accounting for massive dilatonic gauge field. Finally, the standard diffeomorphism symmetry of gravitation is extended by resorting to the jet-diffeomorphism group, formalism which helps to fix the Hilbert-Einstein Lagrangian in the teleparallelism version.
THE GEOMETRY OF THE HIGGS FIELD
Authors: MADORE J.
Published: April 2008

As a historical remark the similarities are pointed out between a form of chiral action introduced by Schwinger and the formalism used in the noncommutative extensions of electromagnetism.
SUPERMETRICS ON SUPERMANIFOLDS
Authors: SARDANASHVILY G.
Published: April 2008

By virtue of the well-known theorem, a structure Lie group K of a principal bundle P → X is reducible to its closed subgroup H iff there exists a global section of the quotient bundle P/K → X. In gauge theory, such sections are treated as Higgs fields, exemplified by pseudo-Riemannian metrics on a base manifold X. Under some conditions, this theorem is extended to principal superbundles in the category of G-supermanifolds. Given a G-supermanifold M and a graded frame superbundle over M with a structure general linear supergroup, a reduction of this structure supergroup to an orthogonal-symplectic supersubgroup is associated to a supermetric on a G-supermanifold M.
TRIPLE HELIX NETWORKS IN A MULTICULTURAL CONTEXT: TRIGGERS AND BARRIERS FOR FOSTERING GROWTH AND SUSTAINABILITY
Authors: BRUNDIN ETHEL , WIGREN CAROLINE , ISAACS ESLYN , FRIEDRICH CHRIS , VISSER KOBUS
Published: April 2008

This article deals with Triple Helix (university, industry and government cooperation) from an institutional theory perspective. The empirical context is the Western Cape Region in South Africa and the focus is entrepreneurship development. The purpose is two-fold: first, the existing Triple Helix model is adapted to the South African context; and second, facilities and impediments for working according to Triple Helix in South Africa are identified. The empirical material consists of a survey and three longitudinal case studies illustrating the degree of cooperation between the three parties. The article contributes to knowledge about how the Triple Helix model works on a regional level in a developing country. The study draws the following conclusions: when cooperation is to be identified between the three actors, only two of the three are involved; one missing link in the Triple Helix model is the focus on the entrepreneur; cooperation between the three parties are incidental rather than planned and there is lack of structure. In turn, some of these conclusions may be an effect of institutional changes on a national level. For a normative legacy, the article proposes a set of suggestions for incorporating all relevant parties on a practical level.
Asymmetric dimethylarginine inhibits HSP90 activity in pulmonary arterial endothelial cells: role of mitochondrial dysfunction
Authors: Sud Neetu , Wells Sandra M. , Sharma Shruti , Wiseman Dean A. , Wilham Jason , Black Stephen M.
Published: April 2008

Increased asymmetric dimethylarginine (ADMA) levels have been implicated in the pathogenesis of a number of conditions affecting the cardiovascular system. However, the mechanism(s) by which ADMA exerts its effect has not been adequately elucidated. Thus the purpose of this study was to determine the effect of increased ADMA on nitric oxide (NO) signaling and to begin to elucidate the mechanism by which ADMA acts. Our initial data demonstrated that ADMA increased NO synthase (NOS) uncoupling in both recombinant human endothelial NO synthase (eNOS) and pulmonary arterial endothelial cells (PAEC). Furthermore, we found that this endothelial NOS (eNOS) uncoupling increased 3-nitrotyrosine levels preferentially in the mitochondria of PAEC due to a redistribution of eNOS from the plasma membrane to the mitochondria. This increase in nitration in the mitochondria was found to induce mitochondrial dysfunction as determined by increased mitochondrial-derived reactive oxygen species and decreased generation of ATP. Finally, we found that the decrease in ATP resulted in a reduction in the chaperone activity of HSP90 resulting in a decrease in its interaction with eNOS. In conclusion increased levels of ADMA causes mitochondrial dysfunction and a loss of heat shock protein-90 chaperone activity secondary to an uncoupling of eNOS. Mitochondrial dysfunction may be an understudied component of the endothelial dysfunction associated with various cardiovascular disease states.
Neuroinflammation facilitates LIF entry into brain: role of TNF
Authors: Pan Weihong , Yu Chuanhui , Hsuchou Hung , Zhang Yan , Kastin Abba J.
Published: April 2008

Leukemia inhibitory factor (LIF) is a proinflammatory cytokine mediating a variety of central nervous system (CNS) responses to inflammatory stimuli. During lipopolysaccharide (LPS)-induced inflammation, blood concentrations of LIF increase, correlating with lethality of sepsis. Circulating LIF crosses the blood-brain barrier (BBB) by a saturable transport system. Here we determine how this transport system is regulated in neuroinflammation. Using transport assays that quantify the influx rate and volume of distribution of LIF in mice, we show that LPS facilitated the permeation of LIF from the blood to the brain without compromising the paracellular permeability of the BBB as determined by coadministration of fluorescein. Concurrently, gp130 (shared by the interleukin-6 family of cytokines), but not gp190 (the specific receptor for LIF) or cilliary neutrophic factor (CNTF-Rα, a unique receptor for cilliary neurotrophic factor that also uses gp130 and gp190), showed increased levels of mRNA and protein expression in cerebral microvessels from the LPS-treated mice. The upregulation of gp130 by LPS was at least partially mediated by vascular tumor necrosis factor receptor (TNFR)1 and TNFR2. This was shown by elevated TNFR1 and TNFR2 mRNA and protein in cerebral microvessels after LPS and by the absence of the LPS effect on gp130 in knockout mice lacking these receptors. The results show that neuroinflammation by LPS induces endothelial signaling and enhances cytokine transport across the BBB.
Exercise training normalizes enhanced glutamate-mediated sympathetic activation from the PVN in heart failure
Authors: Kleiber Allison C. , Zheng Hong , Schultz Harold D. , Peuler Jacob D. , Patel Kaushik P.
Published: April 2008

Exercise training (ExT) normalizes the increased sympathetic outflow in heart failure (HF), but the mechanisms are not known. We hypothesized that ExT would normalize the augmented glutamatergic mechanisms mediated by N-methyl-d-aspartic acid (NMDA) receptors within the paraventricular nucleus (PVN) that occur with HF. Four groups of rats were used: 1) sham-operated (Sham) sedentary (Sed), 2) Sham ExT, 3) HF Sed, and 4) HF ExT. HF was induced by left coronary artery ligation, and ExT consisted of 3 wk of treadmill running. In α-chloralose-urethane-anesthetized rats, the increase in renal sympathetic nerve activity in response to the highest dose of NMDA (200 pmol) injected into the PVN in the HF Sed group was approximately twice that of the Sham Sed group. In the HF ExT group the response was not different from the Sham Sed and Sham ExT groups. Relative NMDA NR1 receptor subunit mRNA expression was 63% higher in the HF Sed group compared with the Sham Sed group but in the HF ExT group was not different from the Sham Sed and Sham ExT groups. NR1 receptor subunit protein expression was increased 87% in the HF Sed group compared with the Sham Sed group but in the HF ExT group was not significantly different from the Sham Sed and Sham ExT groups. Thus one mechanism by which ExT alleviates elevated sympathetic outflow in HF may be through normalization of glutamatergic mechanisms within the PVN.
Signaling pathways modulated by fish oil in salt-sensitive hypertension
Authors: Diaz Encarnacion Montserrat M. , Warner Gina M. , Gray Catherine E. , Cheng Jingfei , Keryakos Hesham K. H. , Nath Karl A. , Grande Joseph P.
Published: April 2008

Although many studies have indicated that fish oil (FO) improves cardiovascular risk factors and reduces histopathological manifestations of injury in experimental renal injury models, potential mechanisms underlying this protective effect have not been adequately defined. The objective of this study was to identify potential signaling pathways that confer protection in the Dahl rat model of salt-sensitive hypertension. Male Dahl salt-sensitive rats ( n = 10/group) were provided with formulated diets containing 8% NaCl, 20% protein, and 25% FO or 25% corn oil (CO) for 28 days. FO reduced blood pressure (−11% at 4 wk; P < 0.05), urine protein excretion (−45% at 4 wk; P < 0.05), plasma cholesterol and triglyceride levels (−54%, P < 0.001; and −58%, P < 0.05), and histopathological manifestations of renal injury, including vascular hypertrophy, segmental and global glomerular sclerosis, interstitial fibrosis, and tubular atrophy. Interstitial inflammation was significantly reduced by FO (−32%; P < 0.001), as assessed by quantitative analysis of ED1-positive cells in sections of the renal cortex. FO reduced tubulointerstitial proliferative activity, as assessed by Western blot analysis of cortical homogenates for PCNA (−51%; P < 0.01) and quantitative analysis of Mib-1-stained sections of the renal cortex (−42%; P < 0.001). Decreased proliferative activity was associated with reduced phospho-ERK expression (−37%; P < 0.005) and NF-κB activation (−42%; P < 0.05). FO reduced cyclooxygenase (COX)-2 expression (−63%; P < 0.01) and membrane translocation of the NADPH oxidase subunits p47phoxand p67phox(−26 and −34%; P < 0.05). We propose that FO ameliorates renal injury in Dahl salt-sensitive rats through the inhibition of ERK, decreased NF-κB activation, inhibition of COX-2 expression, and decreased NADPH oxidase activation.
Sildenafil acts on the central nervous system increasing sympathetic activity
Authors: Fazan Rubens , Huber Domitila A. , Silva Carlos Alberto A. , Dias da Silva Valdo J. , Salgado Maria Cristina O. , Salgado Helio C.
Published: April 2008

Sildenafil induces vasodilation and is used for treating erectile dysfunction. Although its influence on resting heart function appears to be minimal, recent studies suggest that sildenafil can increase sympathetic activity. We therefore tested whether sildenafil injected into the central nervous system alters the autonomic control of the cardiovascular system in conscious rats. The effect of sildenafil citrate injected into the lateral cerebral ventricle was evaluated in conscious rats by means of the recording of lumbar sympathetic nerve activity (LSNA), spectral analysis of systolic arterial pressure and heart rate variability, spontaneous baroreflex sensitivity, and baroreflex control of LSNA. Intracerebroventricular (ICV, 100 μg/5 μl) administration of sildenafil caused remarkable tachycardia without significant change in basal arterial pressure and was associated with a conspicuous increase (47 ± 14%) in LSNA. Spectral analysis demonstrated that systolic arterial pressure oscillations in the low frequency (LF) range were increased (from 6.3 ± 1.5 to 12.8 ± 3.8 mmHg2), whereas the high frequency (HF) range was not affected by ICV administration of sildenafil. Sildenafil increased pulse interval oscillations at LF and decreased them at HF. The LF-HF ratio increased from 0.04 ± 0.01 to 0.17 ± 0.06. Spontaneous baroreflex sensitivity measured by the sequence method and the baroreflex relationship between mean arterial pressure and LSNA were not affected by ICV administration of sildenafil. In conclusion, sildenafil elicited an increase in sympathetic nerve activity that is not baroreflex mediated, suggesting that this drug is able to elicit an autonomic imbalance of central origin. This finding may have implications for understanding the cardiovascular outcomes associated with the clinical use of this drug.
Physiology and Morphology of Shared and Specialized Spinal Interneurons for Locomotion and Scratching
Authors: Berkowitz Ari
Published: April 2008

Distinct types of rhythmic movements that use the same muscles are typically generated largely by shared multifunctional neurons in invertebrates, but less is known for vertebrates. Evidence suggests that locomotion and scratching are produced partly by shared spinal cord interneuronal circuity, although direct evidence with intracellular recording has been lacking. Here, spinal interneurons were recorded intracellularly during fictive swimming and fictive scratching in vivo and filled with Neurobiotin. Some interneurons that were rhythmically activated during both swimming and scratching had axon terminal arborizations in the ventral horn of the hindlimb enlargement, indicating their likely contribution to hindlimb motor outputs during both behaviors. We previously described a morphological group of spinal interneurons (“transverse interneurons” or T neurons) that were rhythmically activated during all forms of fictive scratching at higher peak firing rates and with larger membrane potential oscillations than scratch-activated spinal interneurons with different dendritic orientations. The current study demonstrates that T neurons are activated during both swimming and scratching and thus are components of the shared circuitry. Many spinal interneurons activated during fictive scratching are also activated during fictive swimming (scratch/swim neurons), but others are suppressed during swimming (scratch-specialized neurons). The current study demonstrates that some scratch-specialized neurons receive strong and long-lasting hyperpolarizing inhibition during fictive swimming and are also morphologically distinct from T neurons. Thus this study indicates that locomotion and scratching are produced by a combination of shared and dedicated interneurons whose physiological and morphological properties are beginning to be revealed.
Increased Chlorophyll Levels in the Southern Caspian Sea Following an Invasion of Jellyfish
Authors: Kideys Ahmet E. , Roohi Abolghaseem , Eker-Develi Elif , Mélin Frédéric , Beare Doug
Published: April 2008

A significant correlation was observed between satellite derived chlorophylla(Chla) concentrations and the biomass of the invasive comb jellyfishMnemiopsis leidyiin the southern Caspian Sea. By consuming the herbivorous zooplankton, the predatory ctenophoreM. leidyimay have caused levels of Chlato rise to very high values ( mg ) in the southern Caspian Sea. There might also be several other factors concurrent with predation effects ofM. leidyiinfluencing Chlalevels in this region, such as eutrophication and climatic changes which play major roles in nutrient, phytoplankton, and zooplankton variations. The decrease in pelagic fishes due to overfishing, natural, and anthropogenic impacts might have provided a suitable environment forM. leidyito spread throughout this enclosed basin.
Delay Efficient 32‐Bit Carry‐Skip Adder
Authors: Lin Yu Shen , Radhakrishnan Damu
Published: April 2008

The design of a 32‐bit carry‐skip adder to achieve minimum delay is presented in this paper.
A fast carry look‐ahead logic using group generate and group propagate functions is used to speed up the performance of multiple stages of ripple carry adders.
The group generate and group propagate functions are generated in parallel with the carry generation for each block. The optimum block sizes are decided by considering the critical path into account.
The new architecture delivers the sum and carry outputs in lesser unit delays than existing carry‐skip adders. The adder is implemented in 0.25 μm CMOS technology at 3.3 V. The critical delay for the proposed adder is 3.4 nanoseconds. The simulation results show that the proposed adder is 18% faster than the current fastest carry‐skip adder.
Preparation of Glass Plate‐Supported Nanostructure ZnO Thin Film Deposited by Sol‐Gel Spin‐Coating Technique and Its Photocatalytic Degradation to Monoazo Textile Dye
Authors: Habibi Mohammad Hossein , Sardashti Mohammad Khaledi
Published: April 2008

Glass plate‐supported nanostructure ZnO thin films were deposited by sol‐gel spin coating. Films were preheated at 275∘C for 10 minutes and annealed at 350, 450, and 550∘C for 80 minutes. The ZnO thin films were transparent ca 80–90% in visible range and revealed that absorption edges at about 370 nm. The c‐axis orientation improves and the grain size increases which was indicated by an increase in intensity of the (002) peak at 34.4∘ in XRD corresponding to the hexagonal ZnO crystal. The photocatalytic degradation of X6G an anionic monoazo dye, in aqueous solutions, was investigated and the effects of some operational parameters such as the number of layer and reusability of ZnO nanostructure thin film were examined. The results showed that the five‐layer coated glass surfaces have a very high photocatalytic performance.
Mechanical Properties and Decay Resistance ofHornbeam Cement Bonded Particleboards
Authors: Papadopoulos Antonios N.
Published: April 2008

Cement bonded particleboards were manufactured from hornbeam (Carpinus betulusL.) wood particles. Hydration tests were carried out to determine the inhibitory index in order to characterise wood-cement compatibility. The results revealed that the mixture of hornbeam-cement can be classified as moderate inhibition. Two wood: cement ratios were applied in this study, namely, 1 : 3 and 1 : 4, for the board manufacture. It was found that an increase of cement-wood ratio resulted in an improvement in all properties examined, except MOR. All properties of the boards made from 1 : 4 wood: cement ratio surpassed the minimum requirements set forth by the building type HZ code. Boards were exposed to brown and white rot fungi,Coniophora puteana, andTrametes versicolor, respectively. Overall, both fungi failed to attack the cement-bonded boards.
C‐Peptide and Atherogenesis: C‐Peptide as a Mediator of Lesion Development in Patients with Type 2 Diabetes Mellitus?
Authors: Marx Nikolaus , Walcher Daniel
Published: April 2008

Patients with insulin resistance and early type 2 diabetes exhibit an increased propensity to develop a diffuse and extensive pattern of arteriosclerosis. Typically, these patients show increased levels of C‐peptide and over the last years various groups examined the effect of C‐peptide in vascular cells as well as its potential role in lesion development. While some studies demonstrated beneficial effects of C‐peptide, for example, by showing an inhibition of smooth muscle cell proliferation, others suggested proatherogenic mechanisms in patients with type 2 diabetes. Among them, C‐peptide may facilitate the recruitment of inflammatory cells into early lesions and promote lesion progression by inducing smooth muscle cell proliferation. The following review will summarize the effects of C‐peptide in vascular cells and discuss the potential role of C‐peptide in atherogenesis in patients with type 2 diabetes.
CFP and YFP, but Not GFP, Provide Stable Fluorescent Marking of Rat Hepatic Adult Stem Cells
Authors: Taghizadeh Rouzbeh R. , Sherley James L.
Published: April 2008

The stable expression of reporter genes in adult stem cells (ASCs) has important applications in stem cell biology. The ability to integrate a noncytotoxic, fluorescent reporter gene into the genome of ASCs with the capability to track ASCs and their progeny is particularly desirable for transplantation studies. The use of fluorescent proteins has greatly aided the investigations of protein and cell function on short‐time scales. In contrast, the obtainment of stably expressing cell strains with low variability in expression for studies on longer‐time scales is often problematic. We show that this difficulty is partly due to the cytotoxicity of a commonly used reporter, green fluorescent protein (GFP). To avoid GFP‐specific toxicity effects during attempts to stably mark a rat hepatic ASC strain and, therefore, obtain stable, long‐term fluorescent ASCs, we evaluated cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP), in addition to GFP. Although we were unable to derive stable GFP‐expressing strains, stable fluorescent clones (up to 140 doublings) expressing either CFP or YFP were established. When fluorescently marked ASCs were induced to produce differentiated progeny cells, stable fluorescence expression was maintained. This property is essential for studies that track fluorescently marked ASCs and their differentiated progeny in transplantation studies.
Unsupervised Learning in Detection of Gene Transfer
Authors: Hamel L. , Nahar N. , Poptsova M.S. , Zhaxybayeva O. , Gogarten J.P.
Published: April 2008

The tree representation as a model for organismal evolution has been in use since before Darwin. However, with the recent unprecedented access to biomolecular data, it has been discovered that, especially in the microbial world, individual genes making up the genome of an organism give rise to different and sometimes conflicting evolutionary tree topologies. This discovery calls into question the notion of a single evolutionary tree for an organism and gives rise to the notion of an evolutionary consensus tree based on the evolutionary patterns of the majority of genes in a genome embedded in a network of gene histories. Here, we discuss an approach to the analysis of genomic data of multiple genomes using bipartition spectral analysis and unsupervised learning. An interesting observation is that genes within genomes that have evolutionary tree topologies, which are in substantial conflict with the evolutionary consensus tree of an organism, point to possible horizontal gene transfer events which often delineate significant evolutionary events.
Nanostructural Organization of Naturally Occurring Composites—Part II: Silica‐Chitin‐Based Biocomposites
Authors: Ehrlich Hermann , Janussen Dorte , Simon Paul , Bazhenov Vasily V. , Shapkin Nikolay P. , Erler Christiane , Mertig Michael , Born René , Heinemann Sascha , Hanke Thomas , Worch Hartmut , Vournakis John N.
Published: April 2008

Investigations of the micro‐ and nanostructures and chemical composition of the sponge skeletons as examples for natural structural biocomposites are of fundamental scientific relevance. Recently, we show that some demosponges (Verongula gigantea, Aplysina sp.) and glass sponges (Farrea occa, Euplectella aspergillum) possess chitin as a component of their skeletons. The main practical approach we used for chitin isolation was based on alkali treatment of corresponding external layers of spicules sponge material with the aim of obtaining alkali‐resistant compounds for detailed analysis. Here, we present a detailed study of the structural and physicochemical properties of spicules of the glass sponge Rossella fibulata. The structural similarity of chitin derived from this sponge to invertebrate alpha chitin has been confirmed by us unambiguously using physicochemical and biochemical methods. This is the first report of a silica‐chitin composite biomaterial found in Rossella species. Finally, the present work includes a discussion related to strategies for the practical application of silica‐chitin‐based composites as biomaterials.
Power Considerations in Banked CAMs: A Leakage Reduction Approach
Authors: Echeverría Pedro , L. Ayala José , López-Vallejo Marisa
Published: April 2008

The content‐based access of CAMs makes them of great interest in lookup‐based operations. However, the large amounts of parallel comparisons required cause an expensive cost in power dissipation. In this work, we present a novel banked precomputation‐based architecture for low‐power and storage‐demanding applications where the reduction of both dynamic and leakage power consumption is addressed. Experimental results show that the proposed banked architecture reduces up to an 89% of dynamic power consumption during the search process while the leakage power consumption is also minimized up to a 91%.
Properties Enhancement of PS Nanocomposites through the POSS Surfactants
Authors: Fu Huei-Kuan , Kuo Shiao-Wei , Yeh Ding-Ru , Chang Feng-Chih
Published: April 2008

Polyhedral oligomeric silsesquioxane (POSS)‐clay hybrids of polystyrene are prepared by two organically modified clays using POSS‐NH2 and C20‐POSS as intercalated agents. X‐ray diffraction (XRD)
studies show the formation of these POSS/clay/PS
nanocomposites in all cases with the disappearance of the peaks
corresponding to the basal spacing of MMT. Transmission electronic
microscopy (TEM) was used to investigate the
morphology of these nanocomposites and indicates that these
nanocomposites are composed of a random dispersion
of exfoliated clay platelets throughout the PS matrix. Incorporation of these
exfoliated clay platelets into the PS matrix led to effectively
increase in glass transition temperature (Tg), thermal decomposition temperature (Td), and the maximum reduction in coefficient of thermal expansion (CTE) is ca. 40% for the C20‐POSS/clay nanocomposite.
Influence of the Synthesis pH on the Properties and Activity of Sol‐Gel TiO2 Photocatalysts
Authors: Marugán Javier , Christensen Paul , Egerton Terry , Purnama Herry
Published: April 2008

The activity of titania photocatalysts is highly dependent on the synthesis procedure. This work reports a study of the correlation between the photocatalytic activity and the physicochemical and photoelectrochemical properties of sol‐gel TiO2 powders and electrodes synthesized using different pH values and temperatures. The activity of the materials has been evaluated using the decolorization of
Reactive Orange 16 (RO16) as model reaction. In contrast with the large number of studies reporting the influence of the temperature, our results point out that preparation pH has even more influence on the crystalline phases and the photocatalytic activity of TiO2 powders and photocurrents of the electrodes. However, the effects on the activity and the photocurrents recorded after immobilization on a conducting support do not vary accordingly. Consequently, our results indicate that the measurement of the photocurrent in an electrolyte media is not a good indicator of the photocatalytic activity of the unsupported system.
Room-Temperature Growth of SiC Thin Films by Dual-Ion-Beam Sputtering Deposition
Authors: Jin C. G. , Wu X. M. , Zhuge L. J.
Published: April 2008

Silicon carbide (SiC) films were prepared by single and dual-ion-beamsputtering deposition at room temperature. An assisted Ar+ ion beam (ion energy Ei = 150 eV) was directed to bombard the substrate surface to be helpful for forming SiC films. The microstructure and optical properties of nonirradicated and assisted ion-beam irradicated films have been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Raman spectra. TEM result shows that the films are amorphous. The films exposed to a low-energy assisted ion-beam irradicated during sputtering from a-SiC target have exhibited smoother and compacter surface topography than which deposited with nonirradicated. The ion-beam irradicated improves the adhesion between film and substrate and releases the stress between film and substrate. With assisted ion-beam irradicated, the density of the Si–C bond in the film has increased. At the same time, the excess C atoms or the size of the sp2 bonded clusters reduces, and the a-Si phase decreases. These results indicate that the composition of the film is mainly Si–C bond.
Dynamics and Stability of the Sampling Distribution ofParticle Swarm Optimisers via Moment Analysis
Authors: Poli Riccardo
Published: April 2008

For stochastic optimisation algorithms, knowing the probability distribution with which
an algorithm allocates new samples in the search space is very important, since this explains
how the algorithm really works and is a prerequisite to being able to match algorithms to
problems. This is the only way to beat the limitations highlighted by the no‐free lunch theory.
Yet, the sampling distribution for velocity‐based particle swarm optimisers has remained a
mystery for the whole of the first decade of PSO research. In this paper, a method is presented
that allows one to exactly determine all the characteristics of a PSO′s sampling distribution
and explain how it changes over time during stagnation (i.e., while particles are in search for
a better personal best) for a large class of PSO′s.
Dynamic Analysis of Coolant Channel and Its Internals of Indian 540 MWe PHWR Reactor
Authors: Dharmaraju N. , Rama Rao A.
Published: April 2008

The horizontal coolant channel is one of the important parts of primary heat transport system in PHWR type of reactors. There are in all 392 channels in the core of Indian 540 MWe reactor. Each channel houses 13 natural uranium fuel bundles and shielding and sealing plugs one each on either side of the channel. The heavy water coolant flows through the coolant channel and carries the nuclear heat to outside the core for steam generation and power production in the turbo-generator. India has commissioned one 540 MWe PHWR reactor in September 2005 and another similar unit will be going into operation very shortly. For a complete dynamic study of the channel and its internals under the influence of high coolant flow, experimental and modeling studies have been carried out. A good correlation has been achieved between the results of experimental and analytical models. The operating life of a typical coolant channel typically ranges from 10 to 15 full-power years. Towards the end of its operating life, its health monitoring becomes an important activity. Vibration diagnosis plays an important role as a tool for life management of coolant. Through the study of dynamic characteristics of the coolant channel under simulated loading condition, an attempt has been made to develop a diagnostics to monitor the health of the coolant channel over its operating life. A study has been also carried out to characterize the fuel vibration under different flow condition.
Algorithms for Sparse Nonnegative Tucker Decompositions
Authors: Mørup Morten , Hansen Lars Kai , Arnfred Sidse M.
Published: April 2008

There is a increasing interest in analysis of large-scale multiway data. The concept of multiway data refers to arrays of data with more than two dimensions, that is, taking the form of tensors. To analyze such data, decomposition techniques are widely used. The two most common decompositions for tensors are the Tucker model and the more restricted PARAFAC model. Both models can be viewed as generalizations of the regular factor analysis to data of more than two modalities. Nonnegative matrix factorization (NMF), in conjunction with sparse coding, has recently been given much attention due to its part-based and easy interpretable representation. While NMF has been extended to the PARAFAC model, no such attempt has been done to extend NMF to the Tucker model. However, if the tensor data analyzed are nonnegative, it may well be relevant to consider purely additive (i.e., nonnegative) Tucker decompositions). To reduce ambiguities of this type of decomposition, we develop updates that can impose sparseness in any combination of modalities, hence, proposed algorithms for sparse nonnegative Tucker decompositions (SN-TUCKER). We demonstrate how the proposed algorithms are superior to existing algorithms for Tucker decompositions when the data and interactions can be considered nonnegative. We further illustrate how sparse coding can help identify what model (PARAFAC or Tucker) is more appropriate for the data as well as to select the number of components by turning off excess components. The algorithms for SN-TUCKER can be downloaded from Mørup (2007).