Home About us Contact
|
Home About us Contact | ||
|
|
||
Several Systems (several + system)
Selected AbstractsA modular approach to addressing model design, scale, and parameter estimation issues in distributed hydrological modellingHYDROLOGICAL PROCESSES, Issue 2 2002G. H. Leavesley Abstract A modular approach to model design and construction provides a flexible framework in which to focus the multidisciplinary research and operational efforts needed to facilitate the development, selection, and application of the most robust distributed modelling methods. A variety of modular approaches have been developed, but with little consideration for compatibility among systems and concepts. Several systems are proprietary, limiting any user interaction. The US Geological Survey modular modelling system (MMS) is a modular modelling framework that uses an open source software approach to enable all members of the scientific community to address collaboratively the many complex issues associated with the design, development, and application of distributed hydrological and environmental models. Implementation of a common modular concept is not a trivial task. However, it brings the resources of a larger community to bear on the problems of distributed modelling, provides a framework in which to compare alternative modelling approaches objectively, and provides a means of sharing the latest modelling advances. The concepts and components of the MMS are described and an example application of the MMS, in a decision-support system context, is presented to demonstrate current system capabilities. Copyright © 2002 John Wiley & Sons, Ltd. [source] Enhancing psychotherapy outcomes via providing feedback on client progress: a replicationCLINICAL PSYCHOLOGY AND PSYCHOTHERAPY (AN INTERNATIONAL JOURNAL OF THEORY & PRACTICE), Issue 2 2002Michael J. Lambert Several systems have been developed to monitor and feedback information about a client's responses to psychotherapy as a method of enhancing client outcome. The current study divided 1020 clients into four groups (two experimental and two control) to determine if feedback regarding client progress, when provided to a therapist, affected client outcome and number of sessions attended. Results showed that feedback increased the duration of treatment and improved outcome for clients identified as potential treatment failures thereby replicating an earlier study using nearly identical methodology. Nearly twice as many clients in the feedback group achieved clinically significant or reliable change and fewer were classified as deteriorated by the time treatment ended. For those clients who were predicted to have a positive response to treatment, feedback to therapists resulted in an equal number of treatment sessions and equivalent outcomes compared to the no feedback controls. The results are discussed in terms of quality management in routine clinical practice and the need to base treatment decisions on clients' response to treatment rather than arbitrary session limits. Suggestions for additional research aimed at enhancing the effects of feedback on client outcome are made. Copyright © 2002 John Wiley & Sons, Ltd. [source] Switching of the transmitters that mediate hindbrain correlated activity in the chick embryoEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2009Hiraku Mochida Abstract Widely propagating correlated neuronal activity is a hallmark of the developing nervous system. The activity is usually mediated by multiple transmitters, and the contribution of gap junctions has also been suggested in several systems. In some structures, such as the retina and spinal cord, it has been shown that the dominant transmitter mediating the correlated wave switches from acetylcholine to glutamate during development, although the functional significance of this phenomenon has not been clarified. An important question is whether such a transmitter switch occurs in other systems, especially in the brain. In the present study, we demonstrate that the major transmitter mediating correlated wave activity in the embryonic chick hindbrain changes from acetylcholine/,-aminobutyric acid (GABA)/glycine to glutamate/GABA as development proceeds. The results show for the first time that the dominant transmitter switches from acetylcholine to glutamate in a region other than the retina and spinal cord. This finding sheds more light on the role of nicotinic acetylcholine receptors in the generation of correlated wave activity, which is considered to regulate the development of the nervous system. [source] Molecular Transport Junctions: Clearing Mists,ADVANCED MATERIALS, Issue 1 2007M. Lindsay Abstract Recent progress in the measurement and modeling of transport in molecular junctions has been very significant. Tunnel transport in the Landauer,Imry regime is now broadly understood for several systems, although a detailed understanding of the role of contact geometry is still required. We overview some clear indications from recent research and note the quite reasonable agreement between measured and calculated conductance in metal,molecule,metal junctions. The next challenge lies in obtaining a microscopic understanding of charge transport that involves reduction or oxidation of molecules. [source] Are the Hirshfeld and Mulliken population analysis schemes consistent with chemical intuition?INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 9 2009Soumen Saha Abstract In the present article, we report a comparative study between the Hirshfeld and Mulliken population analysis schemes (abbreviated as HPA and MPA, respectively). Trends of atomic charges derived from these two population analysis schemes are compared with those expected from other commonly used chemical concepts like electronegativity, inductive effects, and resonance effects. Although previous studies on intramolecular reactivity sequences demonstrated that HPA generates reliable and non-negative (and thus physically more realistic) condensed Fukui function (FF) values, the present study reveals problems with the HPA charge partitioning technique. Specifically, HPA fails to reproduce reliable intermolecular and intramolecular charge trends in several systems. Reasons for the success and failure of HPA are discussed and a method for improving the Hirshfeld charge partitioning is proposed. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Applicability of MNDO techniques AM1 and PM3 to ring-structured polymersJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 12 2002L. Y. A. Dávila Abstract Semiempirical Hartree-Fock techniques are widely used to study properties of long ring-structured chains, although these types of systems were not included in the original parametrization ensembles. These techniques are very useful for an ample class of studies, and their predictive power should be tested. We present here a study of the applicability of some techniques from the NDDO family (MNDO, AM1, and PM3) to the calculation of the ground state geometries of a specific set of molecules with the ring-structure characteristic. For this we have chosen to compare results against ab initio Restricted Hartree-Fock 6-31G(d,p) calculations, extended to Mřller-Plesset 2 perturbation theory for special cases. The systems investigated comprise the orthobenzoquinone (O2C6H4) molecule and dimers (O2C6H4)2, as well as trimers of polyaniline, which present characteristics that extend to several systems of interest in the field of conducting polymers, such as ring structure and heterosubstitution. We focus on the torsion between rings, because this angle is known to affect strongly the electronic and optical properties of conjugated polymers. We find that AM1 is always in qualitative agreement with the ab initio results, and is thus indicated for further studies of longer, more complicated chains. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 1135,1142, 2002 [source] Thermal machines based on surface energy of wetting: Thermodynamic analysisAICHE JOURNAL, Issue 3 2003A. Laouir This work proposes an original thermodynamic-energetic analysis of the feasibility and ideal performance of thermal machines based on the wetting phenomenon proposed by V. A. Eroshenko. The extension or contraction of a liquid film is taken as a "tutorial" example to introduce the basic thermodynamic relations of this 2-D transformation. It implies both mechanical and thermal effects, and this coupling allows conversion of heat to work (thermal engine) or conversely to pump heat (refrigeration/heat pump effect). A similar approach is then developed for the interface between a liquid and a highly microporous solid, having a large internal surface area. The thermodynamic behavior of this interface involves as state variables the surface tension of the liquid, the contact angle, and their dependence on temperature. Depending on the relative magnitude and sign of these quantities, and, therefore, on the working couple and the temperature range, a variety of machine cycles are feasible, or excluded, and a method is proposed for a comprehensive inventory. Order-of-magnitude calculations of the energy densities are presented based on the existing experimental data for several systems involving water as the fluid. The tentative conclusions are that the energy densities are very small on a mass basis compared to conventional systems based on vaporization, but the contrary is true on a volume basis because the phase transformation (extension of the surface) occurs in a condensed state. There may, therefore, be some niches for thermal machines of this type, but they remain to be identified and validated. [source] Melatonin treatment protects against ischemia/reperfusion-induced functional and biochemical changes in rat urinary bladderJOURNAL OF PINEAL RESEARCH, Issue 3 2003Göksel, ener Abstract: Reactive oxygen metabolites play important roles in ischemia/reperfusion (I/R) injury in several systems. The aim of this study was to investigate the role of melatonin against I/R injury of the rat urinary bladder. The abdominal aorta was clamped to induce ischemia for 30 min, then the animals were subjected to 60 min of reperfusion. Melatonin (10 mg/kg, i.p.) or the vehicle (control 1% alcohol i.p.) was administered before I/R. After decapitation, the bladder was removed and the tissue was either used for functional studies or stored for measurement of products of lipid peroxidation (LP), glutathione (GSH) levels and myeloperoxidase activity (MPO). Bladder strips were suspended in oxygenated Tyrode's buffer at 37°C and isometric contractions to carbachol (CCh; 10,8,10,4 m) were recorded. In the I/R group, the contractile responses of the bladder strips were lower than those of the control group (P < 0.01,0.001) and were reversed by treatment with melatonin (P < 0.05,0.001). LP which was higher in I/R group compared with control (27.68 ± 1.69 and 10.59 ± 1.27 nmol/g, respectively; P < 0.001) was partially reversed by melatonin (19.01 ± 1.85 nmol/g; P < 0.01). Similarly, GSH showed a decrease in the I/R group compared with controls (0.27 ± 0.03 and 0.43 ± 0.04 ,mol/g, respectively; P < 0.05) and melatonin prevented this effect completely (0.45 ± 0.04 , mol/g; P < 0.05). MPO activity in the I/R group (4.19 ± 0.08 U/g) was significantly higher than that of the control group (1.41 ± 0.08 U/g; P < 0.001) and melatonin treatment reduced MPO levels compared with I/R alone (3.16 ± 0.07; P < 0.001). Melatonin almost completely reversed the low contractile responses of rat urinary bladder strips to CCh and prevented oxidative tissue damage following I/R. [source] Ionic liquids in the synthesis and modification of polymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2005Przemys, aw Kubisa Abstract Ionic liquids are organic salts that are liquid at ambient temperatures, preferably at room temperature. They are nonvolatile, thermally and chemically stable, highly polar liquids that dissolve many organic, inorganic, and metallo-organic compounds. Many combinations of organic cations with different counterions are already known, and the properties of ionic liquids may be adjusted by the proper selection of the cation and counterion. In the last decade, there has been increasing interest in using ionic liquids as solvents for chemical reactions. The interest is stimulated not only by their nonvolatility (green solvents) but also by their special properties, which often affect the course of a reaction. In recent years, ionic liquids have also attracted the attention of polymer chemists. Although the research on using ionic liquids in polymer systems is still in its infancy, several interesting possibilities have already emerged. Ionic liquids are used as solvents for polymerization processes, and in several systems they indeed show some advantages. In radical polymerization, the kp/kt ratio (where kp is the rate constant of propagation and kt is the rate constant of termination) is higher than in organic media, and thus better control of the process can be achieved. Ionic liquids, as electrolytes, have also attracted the attention of researchers in the fields of electrochemical polymerization and the synthesis of conducting polymers. Finally, the blending of ionic liquids with polymers may lead to the development of new materials (ionic liquids may act as plasticizers, electrolytes dispersed in polymer matrices, or even porogens). In this article, the new developments in these fields are briefly discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4675,4683, 2005 [source] Further examining the triangle tip: Improving support for students with emotional and behavioral needsPSYCHOLOGY IN THE SCHOOLS, Issue 1 2009Lee Kern Students identified as having emotional and behavioral disorders (EBD) experience the poorest educational outcomes among any disability group. Although models of intervention and corresponding evidence-based practices continue to advance, the promise of new approaches has failed to reach the general population of students with EBD. In this artice, we visit possible explanations for these continued poor outcomes. Breakdowns along several systems are discussed, including placement and related practices as well as the absence of individualized approaches. In addition, we offer suggestions for improvement. © 2008 Wiley Periodicals, Inc. [source] Evaluating Options for Utility-Based Kidney AllocationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 7 2009D. L. Segev Over the last 5 years, a number of utility-based allocation systems have been proposed in an effort to increase the life-prolonging potential of deceased donor kidneys in the United States. These have included various adaptations of age-matching and net benefit, including the Eurotransplant Senior Program, Life Years From Transplant, and several systems for avoiding extreme donor/recipient mismatch. However, utility-based allocation is complex and raises issues regarding choice of metric, appropriateness of certain factors for use in allocation, accuracy of prediction models, transparency and perception, and possible effects on donation rates. Changing the role of utility in kidney allocation will likely cause changes to efficiency, equity, predictability, autonomy, controversy, trust and live donation. In this manuscript, various allocation systems are discussed, and a framework is proposed for quantifying the goals of the transplant community and evaluating options for utility-based kidney allocation in this context. [source] Direct current decreases cell viability but not P-glycoprotein expression and function in human multidrug resistant leukemic cellsBIOELECTROMAGNETICS, Issue 7 2001Carla Holandino Abstract Inhibition of tumor growth induced by treatment with direct current (DC) has been reported in several systems. In the current work, the cellular effects generated by the DC treatment of the human leukemic K562 cell line and its vincristine-resistant derivative K562-Lucena 1 were analyzed by trypan blue staining and transmission electron microscopy. DC stimulation induced cell lysis, alterations in shape, membrane extraction or discontinuity, and intense vacuolization of some cells. In addition, treatment of K562 and K562-Lucena 1 cells caused a marked decrease in viability. Since multidrug resistance is a major factor contributing with failure of chemotherapy in many tumors, the expression and function of P-glycoprotein (P-gp) in K562-Lucena 1 cells were also studied. The expression of mdr1, the gene encoding P-gp, was analyzed by reverse transcription polymerase chain reaction, which showed that this gene was equally expressed in either treated or untreated cells. These results were confirmed by flow cytometry with a monoclonal anti P-gp antibody and the Rhodamine 123 extrusion method, which revealed that P-gp surface expression and function were unaltered after DC treatment. Our results suggest that DC treatment does not affect P-gp in human leukemic cells, but affects their viability by mechanisms that would involve clear cellular effects, but also additional targets, whose relevance in dc treated tumoral cells is currently discussed. Bioelectromagnetics 22:470,478, 2001. © 2001 Wiley-Liss, Inc. [source] Inhibition of fatty acid amide hydrolase by kaempferol and related naturally occurring flavonoidsBRITISH JOURNAL OF PHARMACOLOGY, Issue 2 2008L Thors Background and purpose: Recent studies have demonstrated that the naturally occurring isoflavone compounds genistein and daidzein inhibit the hydrolysis of anandamide by fatty acid amide hydrolase (FAAH) in the low micromolar concentration range. The purpose of the present study was to determine whether this property is shared by flavonoids. Experimental approach: The hydrolysis of anandamide in homogenates and intact cells was measured using the substrate labelled in the ethanolamine part of the molecule. Key results: Twenty compounds were tested. Among the commonly occurring flavonoids, kaempferol was the most potent, inhibiting FAAH in a competitive manner with a Ki value of 5 ,M. Among flavonoids with a more restricted distribution in nature, the two most active toward FAAH were 7-hydroxyflavone (IC50 value of 0.5,1 ,M depending on the solvent used) and 3,7-dihydroxyflavone (IC50 value 2.2 ,M). All three compounds reduced the FAAH-dependent uptake of anandamide and its metabolism by intact RBL2H3 basophilic leukaemia cells. Conclusions and implications: Inhibition of FAAH is an additional in vitro biochemical property of flavonoids. Kaempferol, 7-hydroxyflavone and 3,7-dihydroxyflavone may be useful as templates for the synthesis of novel compounds, which target several systems that are involved in the control of inflammation and cancer. British Journal of Pharmacology (2008) 155, 244,252; doi:10.1038/bjp.2008.237; published online 16 June 2008 [source] Extrahelical Damaged Base Recognition by DNA Glycosylase EnzymesCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2008James Abstract The efficient enzymatic detection of damaged bases concealed in the DNA double helix is an essential step during DNA repair in all cells. Emergent structural and mechanistic approaches have provided glimpses into this enigmatic molecular recognition event in several systems. A ubiquitous feature of these essential reactions is the binding of the damaged base in an extrahelical binding mode. The reaction pathway by which this remarkable extrahelical state is achieved is of great interest and even more debate. [source] | |||||||||||||||||||