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Various Systems (various + system)
Selected AbstractsSURFACE ROUGHNESS OF PACKABLE COMPOSITE RESINS POLISHED WITH VARIOUS SYSTEMSJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 1 2004Jack L. Ferracane PhD [source] Planetary landscape systems: a limitless frontierEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2008Victor R. Baker Abstract If it is to be a complete science of landforms and landscapes, geomorphology is not appropriately limited geographically to the terrestrial portions of Earth's surface. Various systems of landforms and their generative processes are best understood in a full planetary context. Moreover, by extending its purview to include the nature of landscapes on Earth-like planets, geomorphological inquiry is not appropriately limited in its philosophical presumptions to the reductionist views that have so successfully guided much of physics. Holistic thinking, exemplified by some aspects of evolutionary biology, and a systems framework may prove to be particularly fruitful for understanding future extraterrestrial discoveries and the general nature of landforms and landscapes. Copyright © 2008 John Wiley & Sons, Ltd. [source] Phase determination via Sayre-type equations with anomalous-scattering dataACTA CRYSTALLOGRAPHICA SECTION A, Issue 3 2001Jeffrey Roach The necessary background for the analysis of complex-valued electron-density maps is established. Various systems of structure-factor equations of convolutional type akin to Sayre's squaring method equations are tested for agreement on the real and imaginary parts of the electron density as well as approximations thereof. A system of convolutional structure-factor equations holding in a complex-valued electron density generated by two atom types is developed. The scope of application of these equations is determined and it is shown that the equations provide a method of extrapolating high-resolution phases from a low-resolution base phase set without introducing further model bias. Additional applications to phase refinement are explored. [source] The in vitro effects of melatonin on human sperm function and its scavenging activities on NO and ROSANDROLOGIA, Issue 2 2010S. S. Du Plessis Summary Various systems of antioxidants exist endogenously in the body to help protect it against free radical damage by scavenging excessive ROS and RNS. Melatonin, a hormone secreted by the pineal gland, and responsible for controlling the circadian rhythm, is one such endogenous antioxidant. Melatonin has been reported to be present in human seminal fluid, but its antioxidant activities in semen are rather contradictory. This study aimed at establishing the effects of melatonin treatment on human spermatozoa. Spermatozoa were incubated with 2 mm melatonin (120 min, 37 °C, 5% CO2) after which motility parameters were measured by computer aided motility analysis, while cell viability (PI), intracellular NO (DAF-2/DA) and ROS (DCFH-DA) were assessed using flow cytometry. In vitro melatonin treated samples (n = 12) showed a significantly higher percentage of motile, progressive motile and rapid cells, while simultaneously reducing the number of nonviable spermatozoa when compared with the control. Endogenous NO was significantly decreased, but no effect was observed on ROS levels. From these results, it can be concluded that melatonin was able to directly or indirectly scavenge NO, as indicated by the reduction in 4,5-diaminofluorescein-2/diacetate fluorescence. Future studies will indicate whether melatonin treatment during sperm preparation techniques could protect spermatozoa from excessive NO production. [source] Gene expression profiles of lens regeneration and development in Xenopus laevisDEVELOPMENTAL DYNAMICS, Issue 9 2009Erica L. Malloch Abstract Seven hundred and thirty-four unique genes were recovered from a cDNA library enriched for genes up-regulated during the process of lens regeneration in the frog Xenopus laevis. The sequences represent transcription factors, proteins involved in RNA synthesis/processing, components of prominent cell signaling pathways, genes involved in protein processing, transport, and degradation (e.g., the ubiquitin/proteasome pathway), matrix metalloproteases (MMPs), as well as many other proteins. The findings implicate specific signal transduction pathways in the process of lens regeneration, including the FGF, TGF-beta, MAPK, Retinoic acid, Wnt, and hedgehog signaling pathways, which are known to play important roles in eye/lens development and regeneration in various systems. In situ hybridization revealed that the majority of genes recovered are expressed during embryogenesis, including in eye tissues. Several novel genes specifically expressed in lenses were identified. The suite of genes was compared to those up-regulated in other regenerating tissues/organisms, and a small degree of overlap was detected. Developmental Dynamics 238:2340,2356, 2009. © 2009 Wiley-Liss, Inc. [source] The Choice Among Interbank Settlement Systems: The European ExperienceECONOMIC NOTES, Issue 1 2003Angelo Baglioni This paper addresses the choice of banks between alternative channels for interbank payments. The conventional view assumes a tradeoff between the safety of real-time gross settlement (RTGS) and the liquidity savings of multilateral netting. Moreover, correspondent banking is believed to be inefficient, both in terms of liquidity and of administrative costs. In the last decade, however, the impulse of the Committee on Payment and Settlement Systems, technological changes and the management of RTGS systems by central banks have reduced the difference between the various systems. This is especially true for risk, whereas liquidity cost crucially depends on the refinancing policy adopted by the central bank and the co-ordination among the participants. On the basis of the recent evolution of payment systems in Europe, we verify the importance of liquidity, as well as other variables like transaction costs, for the choice of banks among different settlement systems. Cost factors imply that the nature of payments flows (value, commercial versus financial) and some structural features of the banking systems (dimension of the intermediaries, concentration of the banking sector) become important. The analysis is carried out both through a theoretical model and a cross-country comparison based on three data sources: ECB (European Central Bank, EBA (Euro Banking Association) and SWIFT (Society for Worldwide Interbank Financial Telecommunication). [source] The Reductive Elimination of Methane from ansa -Hydrido(methyl)metallocenes of Molybdenum and Tungsten: Application of Hammond's Postulate to Two-State ReactionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2005José-Luis Carreón-Macedo Abstract The energetic profile of the methane reductive elimination from a selected number of hydrido(methyl)molybdenocene and -tungstenocene derivatives has been calculated by DFT methods. The calculations were carried out for the CH2(C5H4)2M (a -M), SiH2(C5H4)2M (a -H2Si,M), and SiMe2(C5Me4)2M (a -Me2Si,M*) ansa -metallocene systems for M = Mo, W. They include the full optimization of minima [the hydrido(methyl) starting complexes, M(H)(CH3), the intermediate methane complexes, M(CH4), and the metallocene products in the singlet and triplet configurations, (3M and 1M)], transition states (for the methyl hydride reductive elimination, M,TSins, and for the hydrogen exchange, M,TSexch), and the minimum energy crossing point (M,MECP) leading from the singlet methane complexes to the corresponding triplet metallocenes. The results are compared with those previously obtained for the simpler (C5H5)2M (Cp2M) systems (J. C. Green, J. N. Harvey, and R. Poli, J. Chem. Soc., Dalton Trans.2002, 1861). The calculated energy profiles, notably the relative energies of M,TSins and M,MECP, are in agreement with available experimental observations for the a -Me2Si,M* systems. The comparison of the energies and geometries of the rate-determining M,TSins and M,MECP structures with those of the thermodynamically relevant minima for the various systems show the applicability of Hammond's postulate to two-state reactions. However, one notable exception serves to show that the principle is only quantitatively reliable when all the potential energy surfaces for the set of analogous reactions have similar shapes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Wine industry residue as antioxidant in cooked chicken meatINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2010Ligianne Din Shirahigue Summary The effectiveness of grape extracts as food ingredient has been tested in various systems. The objective of this study was to evaluate the efficiency of four concentrations of residues of the wine industry in delaying lipid oxidation in processed chicken meat stored under refrigeration. The development of oxidation during the 14-day storage was evaluated through the thiobarbituric acid reactive substances method (TBAS). The analyses of phenolic compounds and antioxidant activity were performed in grape residue extracts through DPPH (1,1-difenil-2-picrilidrazil) method, lipid peroxidation inhibition and Rancimat. The profile of polyphenols was determined using reversed-phase high-performance liquid chromatography. Isabel grape extract (IGE) and Niagara grape extract (NGE) showed significant content of phenolic compounds. NGE and IGE had high antioxidant activity. The addition of grape extracts significantly increased the oxidative stability of processed and cooked chicken meat during the storage time. The extracts from both grape varieties when applied in concentrations of 40 and 60 mg of GAE, presented results similar to that of Butyl hydroxy toluene (BHT). [source] In Vivo Function of a Differentiation Inhibitor, Id2IUBMB LIFE, Issue 4 2001Yoshifumi Yokota Abstract Cell differentiation is an essential process for the development of various cell types that constitute multicellular organisms. During development, the large family of factors bearing a helix-loop-helix (HLH) motif participates profoundly in this process and these factors serve as good experimental tools for investigating mechanisms underlying tissue-specific differentiation. The HLH family includes both positive and negative regulators of cell differentiation: basic HLH (bHLH)-type transcription factors and Id proteins, respectively. Following an exciting decade focusing on bHLH factors, advances achieved in studies of the inhibitory factors in the last couple of years have placed them in the front line of the research on differentiation and proliferation control. Here, we present and discuss recent results obtained using Id2 -deficient mice, which manifest intriguing phenotypes in various systems. [source] Versatile vacuum chamber for in situ surface X-ray scattering studiesJOURNAL OF SYNCHROTRON RADIATION, Issue 4 2008Dina Carbone A compact portable vacuum-compatible chamber designed for surface X-ray scattering measurements on beamline ID01 of the European Synchrotron Radiation Facility, Grenoble, is described. The chamber is versatile and can be used for in situ investigation of various systems, such as surfaces, nanostructures, thin films etc., using a variety of X-ray-based techniques such as reflectivity, grazing-incidence small-angle scattering and diffraction. It has been conceived for the study of morphology and structure of semiconductor surfaces during ion beam erosion, but it is also used for the study of surface oxidation or thin film growth under ultra-high-vacuum conditions. Coherent X-ray beam experiments are also possible. The chamber is described in detail, and examples of its use are given. [source] Quantifying Fluid Mixing with the Shannon EntropyMACROMOLECULAR THEORY AND SIMULATIONS, Issue 8 2006Marco Camesasca Abstract Summary: We introduce a methodology to quantify the quality of mixing in various systems, including polymeric ones, by adapting the Shannon information entropy. For illustrative purposes we use particle advection of two species in a two-dimensional cavity flow. We compute the entropy by using the probability of finding a suitable chosen group/complex of particles of a given species, at a given location. By choosing the size of the group to be in direct proportion to the overall concentration of the components in the mixture we ensure that the entropic measure is maximized for the case of perfect mixing, that is, when at each location the component concentration is equal to the corresponding overall component concentrations. The scale of observation role in evaluating mixing is analyzed using the entropic methodology. We also illustrate the effect of initial conditions on mixing in a laminar system, typical in operations involving polymers. [source] Finding Meaning in First Episode Psychosis: Experience, Agency, and the Cultural RepertoireMEDICAL ANTHROPOLOGY QUARTERLY, Issue 4 2004JOHN AGGERGAARD LARSEN The article examines individuals' attempts to generate meaning following their experiences with psychosis. The inquiry is based on a person-centered ethnographic study of a Danish mental health community program for early intervention in schizophrenia and involves longitudinal interviews with 15 of its participants. The article takes an existential anthropological perspective emphasizing agency and cultural phenomenology to investigate how individuals draw on resources from the cultural repertoire to make sense of personally disturbing experiences during their psychosis. It is suggested that the concept of "system of explanation" has advantages over, for example, "illness narrative" and "explanatory model" when demonstrating how some individuals engage in the creative analytic and theory-building work of bricolage, selecting, adding, and combining various systems of explanation. Delusions are equally derived from the cultural repertoire but are constructed as dogmatic explanations that are idiosyncratic to the individual who holds them. [source] The law of ownership and control of meteoritesMETEORITICS & PLANETARY SCIENCE, Issue S12 2002Douglas G. SCHMITT This article reviews the law in several countries, international law, and considers the legal and ethical issues facing curators wanting to bring finds to the research community and not divert them to a black market. A survey was made of scientists involved in meteorite acquisition in over 20 countries to determine how well various systems work. Meteorite ownership law is non-uniform. English Common Law, from which the law in former British colonies including the United States evolved, provides that meteorites are the landowner's property; buried meteorites might be part of the mineral rights. Find reporting is not mandatory. Most Western European countries, and former colonies, have civil codes providing that meteorites are owned by the landowner. In many countries legislation about archaeological treasures modifies earlier meteorite law. The UNESCO Convention on the Means of Prohibiting and Preventing the Illicit Import, Export and Transfer of Ownership of Cultural Property provides for tracking and retrieving from reciprocating states, cultural property including meteorites. The Antarctic Treaty does not deal with samples exported. In July 2001 the Antarctic Treaty Consultative parties adopted a resolution to discourage non-scientific collection. Curators should exercise caution if acquiring specimens of questionable legal ownership. Governments should be urged to enact laws to (1) discourage non-scientific collection in pristine areas; (2) encourage collection in populated areas by reasonable incentives to finders, with mandatory find reporting; (3) create efficient export permitting systems allowing exchange of research samples; and (4) retrieve illegally exported meteorites under the UNESCO Cultural Property Convention. [source] Physics with dense positroniumPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2007David B. Cassidy Abstract Our recent experiment on Ps-Ps spin exchange quenching represents the first time that two Ps atoms have been observed interacting with each other. The implication is that experimentation on various systems containing more than one Ps atom is now possible, including the Ps2 molecule, the Ps Bose-Einstein condensate, the Ps atom laser and the annihilation gamma ray laser. Here we describe various aspects of such research, including the development of new techniques, work currently underway and some possible future experiments. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A Retrospective Study on 287 Implants Installed in Resorbed Maxillae Grafted with Fresh Frozen Allogenous BoneCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 2 2010Francesco Carinci MD ABSTRACT Background: Several studies have been performed to evaluate the clinical outcome of implants inserted into maxillae grafted with autogenous bone but few reports have focused on maxillae grafted with fresh-frozen allogenous bone (FFAB). Purpose: The purpose of this study is to retrospectively evaluate the clinical outcome of implants installed in resorbed maxillae augmented with FFAB. Materials and Methods: A total of 69 patients whom had been treated with FFAB grafts to their maxillae and implant placement 4 to 6 months later were retrospectively evaluated. Edentulism was total and partial in 22 and 47 cases, respectively. A total of 287 implants of various systems had been used. A life table analysis was performed. Marginal bone loss was calculated in radiographs. Results: Five of the 287 implants were lost, giving a survival rate (SVR) of 98.3% over a mean follow-up time of 26 months. The marginal bone resorption at the implants was 1.68 mm (SD = 0.44) after 1 year and 1.85 mm (SD = 0.98) after 4 years. The cumulative success rate based on defined criteria was 96% in the first year but decreased to 40% at 4 years because of marginal bone loss. The Kaplan,Meier algorithm demonstrated a better outcome for female patients, removable dentures, and total edentulism. No differences were detected among diameters, lengths, and implant site. Conclusion: Implants placed in FFAB showed a high SVR similar to that reported in previous studies on maxillae grafted with autogenous iliac crest bone. Although our data point to more marginal bone loss in partially edentulous patients and for fixed prosthetic restorations, the use of FFAB for reconstruction of the atrophic jaw prior to implant placement can be considered as a reliable alternative to autogenous bone. [source] | |||||||||||||||||||