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System Leads (system + lead)
Selected AbstractsImaging of the haemorrhagic complications of the haemophiliasJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 1 2009S Constantine Summary Haemorrhage is the main manifestation of the haemophilias. Although acute haemorrhages can be life threatening, especially if involving the central nervous system, repeated haemorrhages involving the musculoskeletal system lead to two conditions unique to patients with haemophilias. This pictorial essay reviews the typical imaging appearances of haemorrhages and consequences in those with haemophilias, with particular emphasis on haemophilic arthropathy and pseudotumours. [source] A ratio-dependent eco-epidemiological model of the Salton SeaMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 2 2006Kusumika Kundu Abstract Ratio-dependent models set up a challenging issue for their rich dynamics incomparison to prey-dependent models. Little attention has been paid so far to describe the importance of transmissible disease in ecological situation by considering ratio-dependent models. In this paper, by assuming the predator response function as ratio-dependent, we consider a model of a system of three non-linear differential equations describing the time evolution of susceptible and infected Tilapia fish population and their predator, the Pelican. Existence and stability analysis of different equilibria of the system lead to different realistic thresholds in terms of system parameters. The condition for extinction of the species is also worked out. Our analytical and numerical studies may be helpful to chalk out suitable control strategies for minimizing the extinction of the Pelicans. We also suggest that supply of alternative food source for predator population may be used as a possible solution to save the predator from their extinction. Copyright © 2005 John Wiley & Sons, Ltd. [source] Organometallic chemistry on rhodaheteroborane clusters: reactions with bidentate phosphines and organotransition metal reagents,APPLIED ORGANOMETALLIC CHEMISTRY, Issue 6-7 2003Oleg Volkov Abstract This article reviews our recent work on the reactions of the rhodaheteroboranes [8,8-(PPh3)2 - nido -8,7-RhSB9H10] (1) and [9,9-(PPh3)2 - nido -9,7,8-RhC2B8H11] (2), and their derivatives, with the bidentate phosphines, dppe [(CH2)2(PPh2)2], dppp [(CH2)3(PPh2)2], and dppm [CH2(PPh2)2], and also with organotransition metal reagents. Simple substitution of the two PPh3 ligands by a single bidentate phosphine takes place when a 1 : 1 molar ratio of base (dppe or dppp) to rhodathiaborane (1) is used. However, in the presence of an excess of dppe or dppp, products containing 1 or 2 mol of base are formed. These products include a bidentate ligand on the metal and a monodentate ligand on the cage. The displaced hydrogen atom from the cage has moved to the metal center. These bis(ligand) species are unstable with respect to the loss of dihydrogen, affording closo -11 vertex clusters with a pendent phosphine ligand on the cage. In concentrated solutions, the pendent phosphine attacks another cage to afford linked clusters. Under both sets of conditions, when dppm is used, only one product is observed. This species has two dppm ligands coordinated to the metal: one in a unidentate mode and the other bidentate. A similar product is obtained in the reaction of 2 with dppm, although the arrangement of the ligands on the metal in the product is different. Ligand exchange experiments on the dppm,thiaborane system lead to results that provide keys to the reaction pathways in some of these processes. The bis(dppm) derivatives of 1 and 2 are amenable to further derivatization. A second metal may be added, either as an exo -polyhedral atom in a nido cluster in which the metal is part of a bidentate ligand, in the case of 1 and 2, or in a closo cluster derivative of 1 in which the metal is bonded to a dangling PPh2 moiety. Thus, it was possible to add the metals iridium, rhodium or ruthenium to the cluster, in the case of 1 and ruthenium in the case of 2. However, the reaction of more electrophilic organotransition metal reagents, such as Wilkinson's catalyst, with the dppm derivative of 1 affords species resulting from removal of ligand rather than incorporation of metal, and the products shed light on the rearrangement processes in these systems. Copyright © 2003 John Wiley & Sons, Ltd. [source] MAPK3 deficiency drives autoimmunity via DC armingEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2010Ivo Bendix Abstract DC are professional APC that instruct T cells during the inflammatory course of EAE. We have previously shown that MAPK3 (Erk1) is important for the induction of T-cell anergy. Our goal was to determine the influence of MAPK3 on the capacity of DC to arm T-cell responses in autoimmunity. We report that DC from Mapk3,/, mice have a significantly higher membrane expression of CD86 and MHC-II and , when loaded with the myelin oligodendrocyte glycoprotein , show a superior capacity to prime naïve T cells towards an inflammatory phenotype than Mapk3+/+ DC. Nonetheless and as previously described, Mapk3,/, mice were only slightly but not significantly more susceptible to myelin oligodendrocyte glycoprotein-induced EAE than WT littermate mice. However, Mapk3+/+ mice engrafted with Mapk3,/, BM (KO,WT) developed a severe form of EAE, in direct contrast to WT,KO mice, which were even less sick than control WT,WT mice. An infiltration of DC and accumulation of Th17 cells was also observed in the CNS of KO,WT mice. Therefore, triggering of MAPK3 in the periphery might be a therapeutic option for the treatment of neuroinflammation since absence of this kinase in the immune system leads to severe EAE. [source] Assessment of the access selection gain in multi-radio access networksEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 3 2009Joachim Sachs In this paper, we investigate the capacity gain of access selection in a multi-radio access network with heterogeneous radio access technologies (RATs). We classify the kinds of gain that can be achieved by access selection: statistical multiplexing in the multi-access system leads to a trunking gain, spatial transmission diversity results from the geographic capacity distribution of the cell layout, stochastic transmission diversity exploits the multi-path fading characteristics. We show how these different properties are affected by the cell layout of the different RATs, the characteristics of each RAT and the traffic load distribution in the network. In a simulation environment the system capacity for the combination of two wide-area access technologies, as well as, for the combination of a wide-area and a local-area access technology is investigated. For this, we compare two different access selection algorithms. One uses the radio link quality as an input parameter, while the other also considers the cell load. We derive quantitative figures for the capacity gain in a large number of scenarios and show that load-based access selection can significantly increase the capacity. We show that the gain of an overlay of local-area access cells provides little capacity gain for uniform geographic load distribution, whereas significant gain can be achieved when most users are located at hotspots. Copyright © 2007 John Wiley & Sons, Ltd. [source] Gaucher disease: mutation and polymorphism spectrum in the glucocerebrosidase gene (GBA),,HUMAN MUTATION, Issue 5 2008Kathleen S. Hruska Abstract Gaucher disease (GD) is an autosomal recessive disorder caused by the deficiency of glucocerebrosidase, a lysosomal enzyme that catalyses the hydrolysis of the glycolipid glucocerebroside to ceramide and glucose. Lysosomal storage of the substrate in cells of the reticuloendothelial system leads to multisystemic manifestations, including involvement of the liver, spleen, bone marrow, lungs, and nervous system. Patients with GD have highly variable presentations and symptoms that, in many cases, do not correlate well with specific genotypes. Almost 300 unique mutations have been reported in the glucocerebrosidase gene (GBA), with a distribution that spans the gene. These include 203 missense mutations, 18 nonsense mutations, 36 small insertions or deletions that lead to either frameshifts or in-frame alterations, 14 splice junction mutations, and 13 complex alleles carrying two or more mutations in cis. Recombination events with a highly homologous pseudogene downstream of the GBA locus also have been identified, resulting from gene conversion, fusion, or duplication. In this review we discuss the spectrum of GBA mutations and their distribution in the patient population, evolutionary conservation, clinical presentations, and how they may affect the structure and function of glucocerebrosidase. Hum Mutat 29(5), 567,583, 2008. Published 2008 Wiley-Liss, Inc. [source] Effect of Different Levels of Wheat Straw Soil Surface Coverage on Weed Flora in Vicia faba CropsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2003D. Bilalis Abstract The crop system implemented on organic farms requires that crop residues are incorporated into the soil following the end of wheat cultivation. This system leads to a reduction in soil moisture and the creation of favourable conditions for the emergence of weeds. In contrast, covering the soil with 60 % crop residues was found to maintain soil moisture and lead to a reduction in dry weed mass, population density and population frequency as well as a reduction in population diversity, regardless of the initial weed flora before the implementation of different soil tillage systems. Finally, an increase in the prevalence of broad-leafed weeds was observed as the level of soil cover increased. [source] A free radical-generating system induces the cholesterol biosynthesis pathway: a role in Alzheimer's diseaseAGING CELL, Issue 2 2009María Recuero Summary Oxidative stress, which plays a critical role in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease (AD), is intimately linked to aging , the best established risk factor for AD. Studies in neuronal cells subjected to oxidative stress, mimicking the situation in AD brains, are therefore of great interest. This paper reports that, in human neuronal cells, oxidative stress induced by the free radical-generating xanthine/xanthine oxidase (X-XOD) system leads to apoptotic cell death. Microarray analyses showed a potent activation of the cholesterol biosynthesis pathway following reductions in the cell cholesterol synthesis caused by the X-XOD treatment; furthermore, the apoptosis was reduced by inhibiting 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) expression with an interfering RNA. The potential importance of this mechanism in AD was investigated by genetic association, and it was found that HMGCR, a key gene in cholesterol metabolism and among those most strongly upregulated, was associated with AD risk. In summary, this work presents a human cell model prepared to mimic the effect of oxidative stress in neurons that might be useful in clarifying the mechanism involved in free radical-induced neurodegeneration. Gene expression analysis followed by genetic association studies indicates a possible link among oxidative stress, cholesterol metabolism and AD. [source] Key Factors of Joint-Liability Loan Contracts: An Empirical AnalysisKYKLOS INTERNATIONAL REVIEW OF SOCIAL SCIENCES, Issue 2 2005Alexander S. Kritikos Summary This paper provides an empirical analysis of joint-liability micro-lending contracts. Using our data set, we examine the efficacy of various incentives set by this contract such as joint-liability between groups of borrowers or group access to future and to larger loans. As proposed by theory, we find that joint liability induces a group formation of low risk borrowers. After the loan disbursement, the incentive system leads to peer monitoring, peer support and peer pressure between the borrowers, thus helping the lending institution to address the moral hazard and enforcement problem. This paper also demonstrates that the mechanism realizes repayment rates of nearly 100% if the loan officers fulfill their complementary duties in the screening and enforcement process. Finally, we make clear that dynamic incentives, in contrast to theory, have to be restricted if the two long-term problems of the joint-liability approach, i.e. its mismatching problem and the domino effect, are to be tackled notably. [source] Preparation and Characterisation of Pd Nanoclusters in Hyperbranched Aramid Templates to be used in Homogeneous CatalysisMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 12 2003Daniela Tabuani Abstract In the present paper the potential use of hyperbranched (HB) aramids as metallic solution stabilisers and carriers for homogeneous catalysis is outlined. Aramids, synthesised either from A2,+,B3 reagents [namely, p -phenylenediamine (PPD) and trimesic acid (TMA)] or from an AB2 monomer [i.e., 5-(4-aminobenzamido)isophtalic acid, named ABZAIA], have been used to stabilise palladium nanoclusters dispersed in two solvent media, namely N,N, -dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The influence of the nature of the polymeric support as well as of the solvent medium on both cluster dimensions and stability of the solutions has been investigated. Indeed, the interactions between the polymeric support and the metallic precursor (PdCl2), as revealed by 1H NMR spectroscopy, involve only the amino groups of the HB aramids. Metal nanocluster dimensions and stability are strongly dependent on the polymer used as a stabilizer. Transmission electron microscopy (TEM) analysis has shown that the presence of HB polymer in the solution reduces cluster dimensions and allows the obtaining of stable systems. The low concentration of NH2 end groups in the poly(AB2) system leads to the formation of Pd particles of rather low dimensions with a high tendency to aggregate. All prepared solutions are stable under inert atmosphere for at least a month, with an improved stabilisation when using the poly(A2,+,B3) system for more than five months. A TEM micrograph of poly(ABZAIA)/Pd from a DMSO solution. [source] Investigation of the Reaction Between Benzophenone and Trimethylaluminium: A Source of Novel Aluminic Activator for Single-site Olefin Polymerization CatalystsMACROMOLECULAR SYMPOSIA, Issue 1 2005Thomas Dalet Abstract The reaction between benzophenone and TMA was investigated in details at 20,°C for different TMA/benzophenone (r) ratios. For r,=,2, a heterodimer µ-(1,1-diphenylethoxy)-µ-methyl-tetramethyldialuminium (B) is only formed. The latter was found able to activate MeDIP(2,6-iPrPh)2FeCl2 catalyst towards ethylene polymerization. Such catalytic system leads to the formation of high molar mass polyethylene with a broad molar mass distribution, without the presence of oligomers, that is attributed to a strong reduction of the transfer reaction to TMA. [source] Scaling of chew cycle duration in primatesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Callum F. Ross Abstract The biomechanical determinants of the scaling of chew cycle duration are important components of models of primate feeding systems at all levels, from the neuromechanical to the ecological. Chew cycle durations were estimated in 35 species of primates and analyzed in conjunction with data on morphological variables of the feeding system estimating moment of inertia of the mandible and force production capacity of the chewing muscles. Data on scaling of primate chew cycle duration were compared with the predictions of simple pendulum and forced mass,spring system models of the feeding system. The gravity-driven pendulum model best predicts the observed cycle duration scaling but isrejected as biomechanically unrealistic. The forced mass,spring model predicts larger increases in chew cycle duration with size than observed, but provides reasonable predictions of cycle duration scaling. We hypothesize that intrinsic properties of the muscles predict spring-like behavior of the jaw elevator muscles during opening and fast close phases of the jaw cycle and that modulation of stiffness by the central nervous system leads to spring-like properties during the slow close/power stroke phase. Strepsirrhines show no predictable relationship between chew cycle duration and jaw length. Anthropoids have longer chew cycle durations than nonprimate mammals with similar mandible lengths, possibly due to their enlarged symphyses, which increase the moment of inertia of the mandible. Deviations from general scaling trends suggest that both scaling of the jaw muscles and the inertial properties of the mandible are important in determining the scaling of chew cycle duration in primates. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] The Fas system in the seminiferous epithelium and its possible extra-testicular roleANDROLOGIA, Issue 1 2003A. Riccioli Summary. The Fas system is involved in the control of immune system homeostasis and nonfunctional Fas system leads to autoimmune disease in mice and humans. The Fas system is a mechanism through which cells expressing Fas ligand (FasL) induce apoptosis of Fas expressing cells. In mouse and rat, the testis represents the main source of constitutive FasL in the body. The roles so far proposed for this molecule in the testis, such as maintenance of immunoprivilege and regulation of physiological germ cell apoptosis, need to be reconsidered as both hypotheses are based on an erroneous cellular location of FasL in the seminiferous epithelium. Recently, we demonstrated that in rodents FasL mRNA is present in germ cells and not in Sertoli cells, and that FasL protein is displayed on the surface of spermatozoa. Here we propose that, for the mouse spermatozoa, the FasL may represent a self-defence mechanism against lymphocytes present in the female genital tract. To verify this hypothesis, we performed crossings between males gld, with nonfunctional FasL, and syngenic or nonsyngenic females. We observed a significant decrease of litter size in outbred crossings with gld males compared with wild-type males, suggesting a possible role of FasL in immunoprotection of the sperm in the female genital tract. The possibility that in humans, by analogy with mouse, FasL plays a self-protective role for the spermatozoon cannot be excluded, and awaits experimental information on the expression of FasL on human sperm cells. [source] Innate immunity and biodefence vaccinesCELLULAR MICROBIOLOGY, Issue 11 2003Nicholas M. Valiante Summary Host defence in vertebrates is achieved by the integration of two distinct arms of the immune system: the innate and adaptive responses. The innate response acts early after infection (within minutes), detecting and responding to broad cues from invading pathogens. The adaptive response takes time (days to weeks) to become effective, but provides the fine antigenic specificity required for complete elimination of the pathogen and the generation of immunologic memory. Antigen-independent recognition of pathogens by the innate immune system leads to the rapid mobilization of immune effector and regulatory mechanisms that provide the host with three critical advantages: (i) initiating the immune response (both innate and adaptive) and providing the inflammatory and co-stimulatory context for antigen recognition; (ii) mounting a first line of defence, thereby holding the pathogen in check during the maturation of the adaptive response; and (iii) steering the adaptive immune system towards the cellular or humoral responses most effective against the particular infectious agent. The quest for safer and more effective vaccines and immune-based therapies has taken on a sudden urgency with the increased threat of bioterrorism. Only a handful of vaccines covering a small proportion of potential biowarfare agents are available for human use (e.g. anthrax and small pox) and these suffer from poor safety profiles. Therefore, next generation biodefence-related vaccines and therapies with improved safety and the capacity to induce more rapid, more potent and broader protection are needed. To this end, strategies to target both the innate and adaptive immune systems will be required. [source] Stress, norepinephrine and depressionACTA NEUROPSYCHIATRICA, Issue 4 2002Brian E. Leonard Experimental and clinical evidence implicates stress as a major predisposing factor in depression and other severe psychiatric disorders. In this review, evidence is presented to show how the impact of stress on the central sympathetic system leads to changes in the endocrine, immune and neurotransmitter axes which underlie the main clinical symptoms of depression. Thus it can be shown that the noradrenergic system is dysfunctional in depression, a situation which reflects the chronic hypersecretion of glucocorticoids and inflammatory mediators within the brain in addition to an enhanced activity of the locus ceruleus. With regard to the actions of antidepressants in modulating the stress response and alleviating depression it is now evident that, irrespective of the presumed specificity of the antidepressants for the noradrenergic or serotonergic systems, they all normalize noradrenergic function. This action is due partly to the regulation of tyrosine hydroxylase activity in the locus ceruleus but also enhances neuronal sprouting which counteracts the neurodegenerative effects of chronic stress. [source] SiO2 Nanoparticle Sequestration via Reactive Functionalization in Holographic Polymer-Dispersed Liquid CrystalsADVANCED MATERIALS, Issue 36 2009John D. Busbee Holographic photopolymerization of reactively functionalized silica nanoparticles in polymer/liquid-crystal systems leads to sequestration of the silica nanoparticles in the polymeric domain of holographic polymer-dispersed liquid-crystals Bragg gratings. Excellent dispersion of the nanoparticles maintains the optical properties of the reflection grating without additional scattering while lowering the voltage necessary to switch the state of the grating. [source] Reaction pathways and reaction progress for the smectite-to-chlorite transformation: evidence from hydrothermally altered metabasitesJOURNAL OF METAMORPHIC GEOLOGY, Issue 1 2002D. Robinson Abstract The transformation from smectite to chlorite has been interpreted as involving either a disequilibrium chlorite/smectite mixed-layering sequence, or an equilibrated discontinuous sequence involving smectite,corrensite,chlorite. Here, analysis of the smectite to chlorite transition in different geothermal systems leads us to propose that the transformation proceeds via three contrasting reaction pathways involving (i) a continuous mixed-layer chlorite/smectite series; (ii) a discontinuous smectite,corrensite,chlorite series and (iii) a direct smectite to chlorite transition. Such contrasting pathways are not in accord with an equilibrium mineral reaction series, suggesting that these pathways record kinetically controlled reaction progress. In the geothermal systems reviewed the style of reaction pathway and degree of reaction progress is closely correlated with intensity of recrystallization, and not to differences in thermal gradients or clay grain size. This suggests a kinetic effect linked to variation in fluid/rock ratios and/or a contrast between advective or diffusive fluid transport. The mode of fluid transport provides a means by which the rates of dissolution/nucleation/growth can control the reaction style and the reaction progress of the smectite to chlorite transition. Slow rates of growth are linked to the first reaction pathway involving mixed-layering, while increasing rates of growth, relative to nucleation, promote the generation of more ordered structures and ultimately lead to the direct smectite to chlorite transition, representative of the third pathway. [source] Spectropolarimetry of a complete infrared-selected sample of Seyfert 2 galaxiesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2001S.L. Lumsden We report the results of a spectropolarimetric survey of a complete far-infrared-selected sample of Seyfert 2 galaxies. We have found polarized broad H, emission in one new source, NGC 5995. In the sample as a whole, there is a clear tendency for galaxies in which we have detected broad H, in polarized light to have warm mid,far-infrared colours in agreement with our previous results. However, a comparison of the optical, radio and hard X-ray properties of these systems leads us to conclude that this is a secondary consequence of the true mechanism governing our ability to see scattered light from the broad-line region. We find a strong trend for galaxies showing such emission to lie above a critical value of the relative luminosity of the active core to the host galaxy (as measured from the [O iii] 5007-Å equivalent width) which varies as a function of the obscuring column density as measured from hard X-ray observations. The warmth of the infrared colours is then largely due to a combination of the luminosity of the active core, the obscuring column and the relative importance of the host galaxy in powering the far-infrared emission, and not solely orientation as we inferred in our previous paper. Our data may also provide an explanation as to why the most highly polarized galaxies, which appear to have tori that are largely edge-on, are also the most luminous and have the most easily detectable scattered broad H,. [source] | ||||||||||||||||||||||