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Various Types (various + type)
Selected AbstractsGender Differences in Various Types of Idiopathic Ventricular TachycardiaJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2002MIKIKO NAKAGAWA M.D. Gender Differences in Idiopathic VT.Introduction: The aim of this study was to evaluate gender differences in the incidence and age distribution of various types of idiopathic ventricular tachycardia (VT). Methods and Results: We conducted a search of the medical literature on idiopathic VT. According to their site of origin, we divided the VTs into three types: right ventricular outflow tract (RVOT-VT), left ventricular outflow tract (LVOT-VT), and left ventricular (LV) septum (LV-VT). We reviewed 68 articles and a total of 748 patients. Among RVOT-VT patients, there were more females than males (311 vs 153, male/female ratio 0.49). In LV-VT, males prevailed over females (175 vs 52, male/female ratio 3.37), whereas LVOT-VT was distributed almost equally between males (n = 33) and females (n = 24). To determine the age distribution, we assessed 419 patients from 51 studies. In both males and females, the highest incidence of RVOT-VT occurred in the third to fifth decade of life (males, mean 43.5 ± 18.7; females, mean 40.9 ± 13.8 years). LV-VT occurred at a younger age in both males and females than did RVOT-VT (mean 33.0 ± 13.9 and 25.7 ± 12.0 years, respectively, P < 0.0001 vs RVOT-VT). LV-VT occurred at a younger age in females than males (P < 0.005). Conclusion: Gender-specific differences exist in the incidence and age distribution of the various types of idiopathic VT. Studies on gender-specific differences in arrhythmia will lead to a better understanding of its mechanism(s) and provide valuable information for the development of optimal treatment strategies. [source] Biosecurity and the Various Types of Embryos TransferredREPRODUCTION IN DOMESTIC ANIMALS, Issue 4 2006M Thibier Contents The aim of the present paper was to review some features related to the risk analysis of three types of embryos to be transferred, namely the in vivo derived, the in vitro produced and the cloned ones. For in vivo -collected embryos, a considerable number of experiments and scientific investigations have been performed and hundreds of thousands of embryos are transferred annually with no contamination of associated diseases. Provided that the code of practice such as that published by the International Embryo Transfer Society is strictly followed by the embryo transfer practitioners, the statement made some 17 years ago saying that the in vivo -derived embryo transfer was the safest way of exchanging genes remains entirely true, thanks to the professionalism of the embryo transfer industry. For the in vitro -produced embryos, some particular rules have to be followed because of specific risks for some pathogens to strongly adhere to the zona pellucida of such embryos. There are some means to monitor and control those effects, and the transfer of in vitro -produced embryos can also be a very safe way to exchange genes around the world. The third type of embryos, the cloned ones, is a quite different category and the risk analysis to be soundly made still needs a lot of investigations so as to characterize the potential risks if there are, in terms not only of disease transmission but also in terms of public health, zoonotic risks as well as those related to quality and safety of food. The problem in this regard, is more directly addressed for offspring of clones than to the cloned embryos themselves. Published data on this issue are increasing in numbers so that progress in that area is expected in the few years to come. [source] Highly Selective Preparation of Allenic and Homopropargylic Hydrazides Through Regiospecific Addition of Propargyltrichlorosilane and Allenyltrichlorosilane to Various Types of N-Acylhydrazones.CHEMINFORM, Issue 24 2006Uwe Schneider Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Highly Selective Formation of Propargyl- and Allenyltrichlorosilanes and Their Regiospecific Addition to Various Types of Aldehydes: Preparation of Both Allenic and Homopropargylic Alcohols.CHEMINFORM, Issue 21 2006Uwe Schneider Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Role of ancillary techniques in diagnosing and subclassifying non-Hodgkin's lymphomas on fine needle aspiration cytologyCYTOPATHOLOGY, Issue 5 2006P. DeyArticle first published online: 8 SEP 200 Non-Hodgkin's lymphomas (NHL) are tumours of the lymphoid cells. During the process of development of lymphoid cells, neoplasia may evolve at any point. Neoplastic cells usually carry the imprint of cell of origin at the stage of origin. Various types of NHL may have similar morphology with wide variation in origin, immunophenotype and other biological features. Different ancillary laboratory techniques may help to overcome the limitations of morphology in this aspect. The commonly used ancillary techniques in lymphomas are immunocytochemistry (IC), flow cytometry, Southern blot (SB) technique, polymerase chain reaction (PCR) and fluorescent in situ hybridization (FISH). In addition, laser scanning cytometry (LSC) and DNA microarray technologies are in the research phase. Various laboratory techniques are used for immunophenotyping, demonstration of monoclonality, identification of chromosomal translocation, assessment of cell kinetics and expression of mRNA in the tumour cells. Flow cytometry helps in rapid immunophenotying of NHL and it has an added advantage over IC in recognizing the co-expression of CD markers. Fine needle aspiration cytology (FNAC) combined with flow immunophenotyping may help us to diagnose and subclassify certain NHLs, such as follicular lymphoma and mantle cell lymphoma, which were previously recognized as pure morphological entities. Loss of morphology is one of the important limitations of flow cytometry. LSC can overcome this limitation by studying morphology along with the immunophenotyping pattern of individual cells. Chromosomal changes in NHL can be identified by SB, PCR and FISH. Molecular diagnosis of NHL helps in diagnosis, subclassification, prognostic assessment and even in planning of therapy. DNA microarray is a relatively newer and promising technology. It gives information about the expression of several thousands of genes in a tumour in a single experiment. In the near future, FNAC combined with ancillary techniques may play a major role in diagnosis, subclassification and management of lymphomas. [source] Endoscopic classification of chronic gastritis based on a pilot study by the research society for gastritisDIGESTIVE ENDOSCOPY, Issue 4 2002Michio Kaminishi Background:,Various types of classification of gastritis have been proposed, but no plausible classification has been available until now. The Research Society for Gastritis performed a pilot study to establish an endoscopic classification, taking into consideration the following: (i) ease of use; (ii) permitting everyone the common image; and (iii) presence of histopathological evidence. Methods:,One hundred and fifty-five patients were enrolled and underwent gastroscopy. Eight basic endoscopic and histological types of gastritis (superficial, hemorrhagic, erosive, verrucous, atrophic, metaplastic, hyperplastic and special types) were defined. Gastritis was endoscopically diagnosed according to the definition of the endoscopic types of gastritis. Four or more biopsy specimens were obtained from the lesser and the greater curvatures of the antrum and the corpus of each patient, and the histological findings of gastritis and Helicobacter pylori infection were assessed. The histological diagnosis of gastritis was made according to the definition of histology types of gastritis. The endoscopic and the histological diagnoses were then compared in a blinded fashion. Results:,Endoscopic diagnosis was 62% as sensitive as histological diagnosis for erosive gastritis, 67% for verrucous gastritis and 84% for atrophic gastritis in the antrum. In superficial gastritis, sensitivity was approximately 25% in the corpus, but only 8% in the antrum. Metaplastic and hyperplastic gastritis were correctly diagnosed only in severe cases. Conclusion:,Five basic types of gastritis (superficial, erosive, verrucous, atrophic and special types) should be employed for the new endoscopic gastritis classification. Metaplastic and hyperplastic gastritis are considered to be subtypes of atrophic gastritis and they should be excluded from the basic endoscopic classification. A new definition of gastritis in the antrum accompanied by redness still remains to be investigated. [source] Highly efficient and chemoselective acetalization of carbonyl compounds catalyzed by new and reusable zirconyl triflate, ZrO(OTf)2HETEROATOM CHEMISTRY, Issue 3 2009Majid Moghadam Various types of aromatic aldehydes were efficiently converted to their corresponding 1,3-dioxanes and 1,3-dioxolane with 1,3-propanediol and ethylene glycol, respectively, in the presence of catalytic amount of ZrO(OTf)2 in acetonitrile at room temperature. The catalyst can be reused several times without loss of its catalytic activity. Very short reaction times, selective acetalization of aromatic aldehydes in the presence of aliphatic aldehydes and ketones, very mild reaction conditions, reusability of the catalyst, and easy workup are noteworthy advantages of this method. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:131,135, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20523 [source] Spectrum of molecular defects and mutation detection rate in patients with severe hemophilia A,HUMAN MUTATION, Issue 3 2005Nadja Bogdanova Abstract Hemophilia A is the most frequently occurring X-linked bleeding disorder, affecting one to two out of 10,000 males worldwide. Various types of mutations in the F8 gene are causative for this condition. It is well known that the most common mutation in severely affected patients is the intron 22 inversion, which accounts for about 45% of cases with F8 residual activity of less than 1%. Therefore, the aim of the present study was to determine the spectrum and distribution of mutations in the F8 gene in a large group of patients with severe hemophilia A who previously tested negative for the common intron 22 inversion. Here we report on a mutation analysis of 86 patients collected under the above-mentioned criterion. The pathogenic molecular defect was identified in all patients, and thus our detection rate was virtually 100%. Thirty-four of the identified mutations are described for the first time. The newly detected amino acid substitutions were scored for potential gross or local conformational changes and influence on molecular stability for every single F8 domain with available structures, using homology modeling. Hum Mutat Res 26(3), 249,254, 2005. © 2005 Wiley-Liss, Inc. [source] Non-inferior Nash strategies for routing control in parallel-link communication networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2005Yong Liu Abstract We consider a routing control problem of two-node parallel-link communication network shared by competitive teams of users. Each team has various types of entities (traffics or jobs) to be routed on the network. The users in each team cooperate for the benefit of their team so as to achieve optimal routing over network links. The teams, on the other hand, compete among themselves for the network resources and each has an objective function that relates to the overall performance of the network. For each team, there is a centralized decision-maker, called the team leader or manager, who coordinates the routing strategies among all entities in his team. A game theoretic approach to deal with both cooperation within each team and competition among the teams, called the Non-inferior Nash strategy, is introduced. Considering the roles of a group manager in this context, the concept of a Non-inferior Nash strategy with a team leader is introduced. This multi-team solution provides a new framework for analysing hierarchically controlled systems so as to address complicated coordination problems among the various users. This strategy is applied to derive the optimal routing policies for all users in the network. It is shown that Non-inferior Nash strategies with a team leader is effective in improving the overall network performance. Various types of other strategies such as team optimization and Nash strategies are also discussed for the purpose of comparison. Copyright © 2005 John Wiley & Sons, Ltd. [source] Food consumption patterns, dietary quality and health status of expectant mothers: case studies in suburban and rural communities in GhanaINTERNATIONAL JOURNAL OF CONSUMER STUDIES, Issue 1 2002Christina A. Nti Abstract The study was conducted to determine the food consumption patterns, dietary quality and health status of expectant women and also to assess their level of awareness of nutritional requirements during pregnancy. Food beliefs, taboos and superstitions held by the women were also investigated. Using the purposive sampling technique, 30 pregnant women attending the Maternal and Child Health Clinic at Dodowa (rural) and University Hospital, Legon (suburban), were selected for the study. A structured questionnaire was used to collect information on the respondents' nutritional knowledge, beliefs, taboos and superstitions and health status. A food frequency questionnaire and the 24-h dietary recall method were used to obtain information on food consumption patterns and dietary quality. The study revealed that, although the majority of the respondents (83.3%) had some knowledge of nutrition, not all were applying it in their feeding practices because of financial constraints. With regard to consumption patterns, most of the women (83.3%) were having three meals a day, while the rest either ate twice a day or anytime they were hungry. Seventy-three per cent of the respondents also increased their food intake during pregnancy. Foods eaten were based mainly on starchy roots and tubers, cereals and vegetables. Legumes, oilseeds and fruits were often lacking in the main meals of respondents. Although animal products were consumed daily, the quantities taken were very small to provide for adequate protein, especially in the rural area. Various types of food were avoided by some of the expectant mothers for reasons such as nausea, loss of appetite, taboos and superstition. With regard to dietary quality, respondents from the rural area had diets of poorer quality in terms of nutrient intake compared with those from the suburban area. In both communities, iron contents of diets were quite low. Forty-seven per cent of the women interviewed were anaemic, with a higher prevalence of anaemia being observed in the rural community. Common ailments reported by the women were dizziness, headache, waist pains and malaria. Based on the results of the study, it was recommended that nutrition education for pregnant women should be stepped up at antenatal clinics especially in rural areas. [source] Jordanian nurses' job stressors and social supportINTERNATIONAL NURSING REVIEW, Issue 1 2008S.H. Hamaideh rn Purpose:, This study describes stressors of Jordanian nurses and the social support they received to decrease the influence of these stressors. The relationships between the two concepts, and each with the sample's demographics were assessed. Predictors of nurses' stressors as well as social supportive behaviours were also studied. Methods:, A descriptive correlational research design was used. The Nursing Stress Scale and the Inventory of Social Supportive Behaviours were used to collect data from a convenience sample of 464 Jordanian nurses who were working in 13 Jordanian hospitals. Results:, Workload and dealing with issues of death and dying were the most prevalent stressors among Jordanian nurses. Emotional support was the most supportive social behaviour Jordanian nurses reported that they usually receive. Significant correlations were found between nurses' stressors and social supportive behaviours, as well as between nurses' stressors and shift worked, level of education, and model of nursing care provision. Additionally, significant correlations were found between social supportive behaviours and commitment for work and units' decision-making style. Shift worked, nurses' educational level and model of nursing care provision were the best predictors of the nurses' stressors. Shift worked, model of the nursing care provision, marital status and unit's organizational structure were the best predictors of the social supportive behaviour. Conclusions:, Nursing interventions are needed to decrease nurses' stressors; these will help nurses to perform safely their jobs. Various types of social support are needed, particularly emotional support. [source] Palladium(II)-Catalyzed Domino Reaction of 2-(1-Alkynyl)-2-alken-1-ones with Nucleophiles: Scope, Mechanism and Synthetic Application in the Synthesis of 3,4-Fused Bicyclic Tetrasubstituted FuransADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2009Yuanjing Xiao Abstract Described herein is the development of a palladium(II)-catalyzed two- or three-component reaction of 2-(1-alkynyl)-2-alken-1-ones with nucleophiles and allylic chlorides. Various types of nucleophiles such as O- , N- , C -based nucleophiles and olefin-tethered O- , N- , C -based nucleophiles were investigated. The scope, mechanism and application of this Pd(II)-catalyzed domino reaction were studied. In these transformations, the palladium catalyst exhibits a dual role, serving simultaneously as a Lewis acid and a transition metal. Two possible reaction pathways (cross-coupling reaction vs. Heck reaction) from the same intermediate furanylpalladium species were observed. The reaction pathway is dependent on the property of the nucleophile and the length of the tethered chain as well. When olefin-tethered O -based nucleophiles were used, only the cross-coupling reaction pathway was observed, in contrast, both reaction pathways were observed when olefin-tethered C -based nucleophiles were employed. The product ratio is dependent on the length of the tethered chain. Furthermore, ring-closing metathesis (RCM) of corresponding furans with CC bonds provides an easy method for the preparation of functionalized oxygen-heterocycles , 3,4-fused bicyclic furans. It is also noteworthy that allylic chloride can be as an oxidant besides its well known function as an alkylating reagent. [source] A phallus for free?JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2003Quantitative genetics of sexual trade-offs in the snail Bulinus truncatus Abstract Resource allocation is thought to play a key role in the coexistence of different sexual morphs within hermaphroditic species. Indeed, most models assume that sexual functions are subject to a balance between reproductive advantage and energetic cost. Various types of cost (e.g. organ construction, maintenance and utilization) and levels of trade-off (physiological and genetic) may be considered. We here examine physiological and genetic costs of phallus construction and maintenance in Bulinus truncatus, a snail species in which aphallic individuals (without phallus) coexist with regular hermaphrodites. We use a quantitative genetic design involving 37 inbred lines (four populations) known to produce different proportions of aphallics, to test for the existence of genetic and nongenetic correlations between aphally and a range of life-history traits over the totality of the life cycle. Our results show that aphallic and euphallic individuals of the same line do not show consistent differences in either growth, fecundity (including offspring survival), or longevity. Furthermore, none of these traits is genetically correlated across lines with the frequency of the aphallic morph. We conclude that the cost of the construction and maintenance of the phallus must be very low in this species. Future studies should investigate the cost associated with using the phallus (i.e. male outcrossing behaviour) to explain the maintenance of high frequencies of aphallic individuals in natural populations. [source] The effect of macromolecular crowding on protein aggregation and amyloid fibril formation,JOURNAL OF MOLECULAR RECOGNITION, Issue 5 2004Larissa A. Munishkina Abstract Macromolecular crowding is expected to have several significant effects on protein aggregation; the major effects will be those due to excluded volume and increased viscosity. In this report we summarize data demonstrating that macromolecular crowding may lead to a dramatic acceleration in the rate of protein aggregation and formation of amyloid fibrils, using the protein ,-synuclein. The aggregation of ,-synuclein has been implicated as a critical factor in development of Parkinson's disease. Various types of polymers, from neutral polyethylene glycols and polysaccharides (Ficolls, dextrans) to inert proteins, are shown to accelerate ,-synuclein fibrillation. The stimulation of fibrillation increases with increasing length of polymer, as well as increasing polymer concentration. At lower polymer concentrations (typically up to ,100,mg/ml) the major effect is ascribed to excluded volume, whereas at higher polymer concentrations evidence of opposing viscosity effects become apparent. Pesticides and metals, which are linked to increased risk of Parkinson's disease by epidemiological studies, are shown to accelerate ,-synuclein fibrillation under conditions of molecular crowding. Copyright © 2004 John Wiley & Sons, Ltd. [source] Characterization of fibronectin assembly by platelets adherent to adsorbed laminin-111JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 5 2006J. CHO Summary.,Background: Various types of laminin (LN) are ubiquitous components of basement membrane and exposed to blood upon localized damage of vascular endothelial cells. Fibronectin is a plasma protein that is insolubilized into fibrils in a regulated fashion by, for example, lysophosphatidic acid (LPA)-stimulated fibroblasts or platelets spread on supportive adhesive ligands. Objective: To study assembly of plasma fibronectin by LPA-activated platelets adherent to LN-111 via ,6,1 integrin. Results: Platelets adherent to LN-111-bound plasma fibronectin or its N-terminal 70 kD fragment in fibrillar arrays at the periphery of spread platelets under static but not shear conditions. Formation of fibronectin arrays under static conditions was inhibited by co-incubation with the N-terminal 70 kD fragment or with a 49-amino acid peptide that binds to the N-terminal region of fibronectin. Approximately 7000 fibronectin dimers bound per adherent platelet with a Kd of 50 nm. Bound 70 kD fragment was readily solubilized with deoxycholate (DOC), whereas bound fibronectin became progressively insoluble. Bound 70 kD fragment became resistant to DOC extraction after treatment with a cell-impermeable, reducible crosslinker. Crosslinked 70 kD fragment was found in a high molecular weight complex. As with fibroblasts, signaling molecules modulating actin cytoskeletal organization controlled expression of binding sites for the N-terminal 70 kD region of fibronectin on adherent platelets. Conclusions: These results indicate that platelets adherent to LN-111 via ,6,1 support subsequent assembly of fibronectin, but possibly only under conditions of intermittent or stagnant blood flow. [source] Fagus sylvatica forest vegetation in Greece: Syntaxonomy and gradient analysisJOURNAL OF VEGETATION SCIENCE, Issue 1 2001Erwin Bergmeier Abstract. This is the first comprehensive study on Fagus sylvatica s.l. forest communities in Greece. It is based on the multivariate analysis of more than 1100 relevés throughout the distribution area of Fagus in Greece, 60 % of which have been sampled within the last 15 years. The data were compiled from all relevant literature and from unpublished field studies. Prior to data analysis, taxonomic and floristic inaccuracies in older literature have been corrected, and some taxa aggregated. Status and distribution of Fagus in Greece, as well as historical and silvicultural aspects, are outlined. Classification resulted in 16 vegetation types defined by species composition, of which 10 units are ranked as association (of which two were described as new) or community, with six subcommunities included. Synonyms from the literature are given to all types. The floristic structure of the data set is displayed by a synoptic table and by DCA ordination. Community differentiation follows a complex edaphic-climatic-phytogeographic pattern. Apart from Fagus sylvatica ssp. orientalis forests of warm and dry habitats and low to medium altitudes which are related to deciduous Quercus forests, four Fagion community groups are distinguished which represent different habitat types: (1) cool, humid, mesotrophic; (2) cool, acidic; (3) high altitude, calcareous; (4) medium altitude, moderately warm and dry. The communities may be assigned to three regional suballiances, viz. (a) Doronico orientalis-Fagenion at medium altitudes of North-Central and East-Central Greece; (b) Doronico columnae-Fagenion in the far north and at high altitudes southward to East-Central Greece; (c) Geranio striati-Fagenion in the Northwest. Various types of thermophilous beech forest are assigned to (a) and (c), acidic forest to (b), and mesic Fagus forest to (b) and (c). [source] Continuity properties of preference relationsMLQ- MATHEMATICAL LOGIC QUARTERLY, Issue 5 2008Marian A. Baroni Abstract Various types of continuity for preference relations on a metric space are examined constructively. In particular, necessary and sufficient conditions are given for an order-dense, strongly extensional preference relation on a complete metric space to be continuous. It is also shown, in the spirit of constructive reverse mathematics, that the continuity of sequentially continuous, order-dense preference relations on complete, separable metric spaces is connected to Ishihara's principleBD -,, and therefore is not provable within Bishop-style constructive mathematics alone. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Heterogeneous hyperactivity and distribution of ischemic lesions after focal cerebral ischemia in Mongolian gerbilsNEUROPATHOLOGY, Issue 4 2006Noriko Katsumata Various types of poststroke hyperactivity exist in humans, but studies of each mechanism using animal models are scarce. We aimed to analyze the heterogeneity of postischemic hyperlocomotion and to identify the ischemic lesions responsible for postischemic hyperlocomotion in rodent models of focal ischemia. Mongolian gerbils underwent right common carotid artery occlusion (CCAO) for 10 or 20 min. At 24 h, 2 days, and 7 days postischemia, we performed quantitative and qualitative locomotor analysis and correlated these results with the extent of ischemic lesions. Intermittent explosive hyperlocomotion was induced transiently in a 10-min CCAO group at 24 h after ischemia and continual unexplosive hyperlocomotion persisted for 7 days in the 20-min CCAO animals. Selective neuronal death, confined to the hippocampal cornu ammonis 1 (CA1), was observed in the 10-min CCAO group and widespread cortical and basal ganglia infarction was observed in the 20-min CCAO group. Amyloid precursor protein was transiently observed in the hippocampus at 24 h postischemia in the 10-min CCAO animals, while it was widely distributed over the ischemic regions throughout the 7 days postischemia in the 20-min CCAO animals. Incidence maps and correlation analysis revealed hippocampal neuronal death of the CA1 sector and widespread hemispheric infarction, including the cortex, as the region responsible for the 10-min and 20-min CCAO-induced hyperactivity, respectively. Two distinct types of locomotor hyperactivity were observed that varied with regard to the distribution of the ischemic lesion, that is, hippocampal neuronal death and widespread infarction involving the cortex. These two types of locomotor hyperactivity appear to be models of the different types of poststroke hyperactivity seen in stroke patients. [source] Investment risk allocation in decentralised electricity markets.OPEC ENERGY REVIEW, Issue 2 2008The need of long-term contracts, vertical integration None of the far-reaching experiments in electricity industry liberalisation was able to ensure the timely and optimal capacity mix development. The theoretical market model features market failures due to the specific volatility of prices, and the difficulty of creating complete markets for hedging. In this paper, we focused on a specific failure, i.e. the impossibility of allocating the various risks borne by the producer onto suppliers and consumers in order to allow capacity development. Promotion of short-term competition by mandating vertical de-integration tends to distort investments in generation by impeding efficient risk allocation. Following Joskow's (2006) line, we developed an empirical analysis of how to secure investments in generation through vertical arrangements between decentralised generators and large purchasers, suppliers or consumers. Empirical observations as risk analysis shows that adopting such arrangements may prove necessary. Various types of long-term contracts between generators and suppliers (fixed-quantity and fixed-price contract, indexed price contract, tolling contract, financial option) appear to offer effective solutions for risk allocation. Vertical integration appears to be another effective way to allocate risk. But it remains an important complementary condition to efficient risk allocation, i.e. that retail competition is sticky or legally limited in order to have a large part of risks borne by consumers on the different market segments. [source] Measurement of sliding velocity and induction time of a single micro-bubble under an inclined collector surfaceTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2008Aref Seyyed Najafi Abstract In this study, interactions between a gas bubble and a flat solid surface were investigated by determining two dynamic parameters, bubble sliding velocity underneath an inclined solid surface and induction time of the gas bubble attaching to the solid surface in aqueous solutions. A single micro-bubble was allowed to move vertically toward an inclined solid surface. After reaching its terminal velocity, the bubble approaches the inclined solid surface and slides underneath it. Complete trajectory of the bubble movement was monitored and recorded by a high-speed CCD video imaging system. Various types of gas bubbles (CO2, air, H2, and O2) and solid surfaces such as bitumen-coated Teflon, hydrophobized and hydrophilic silica were used in sliding velocity and induction time measurements. The effect of water chemistry (industrial process water and de-ionized water) and surface heterogeneity on bubble sliding velocity and induction time was investigated. The results showed that the sliding velocity of micro-bubbles under an inclined solid surface is a strong function of water chemistry, gas type, temperature and hydrophobicity of the solid surface. This study provides relevant information on bubble,solid interactions that would assist in the understanding of bubble,solid attachment under diverse conditions. Dans cette étude, on a étudié les interactions entre une bulle de gaz et une surface solide plane en déterminant deux paramètres dynamiques, la vitesse de glissement de bulle sous une surface de solides inclinée ainsi que le temps d'induction de l'attachement d'une bulle de gaz à une surface solide en solution aqueuse. On a fait se déplacer une micro-bulle unique verticalement vers une surface solide inclinée. Après avoir atteint sa vitesse terminale, la bulle s'approche de la surface solide inclinée et glisse sous elle. La trajectoire complète de la bulle a été enregistrée par un système d'imagerie vidéo CCD à haute vitesse. Différents types de bulles de gaz (CO2, air, H2, et O2) et de surfaces solides telles que du téflon enduit de bitume, de la silice hydrophobe et hydrophile, ont été utilisés dans les mesures de vitesse de glissement et de temps d'induction. L'effet de la chimie de l'eau (eau de procédés industriels et eau déminéralisée) et de l'hétérogénéité de la surface sur la vitesse de glissement et le temps d'induction a été étudié. Les résultats montrent que la vitesse de glissement des micro-bulles sous une surface solide inclinée dépend fortement de la chimie de l'eau, du type de gaz, de la température et de l'hydrophobicité de la surface solide. Cette étude fournit des informations pertinentes sur les interactions bulles-solides pouvant permettre de comprendre l'attachement bulles-solides dans des conditions diverses. [source] Durable Goods, Commitment Power and Public MonopoliesTHE MANCHESTER SCHOOL, Issue 6 2003Gregory E. Goering Since many publicly owned firms manufacture a durable product we examine a simple two-period, constant returns technology, durability choice monopoly model under public ownership. Various types of firm commitment ability are analyzed. The model suggests that many of the standard results of public ownership are not obtained when output is durable. Product durability is shown to be an important factor for public firm subsidization that is independent of the traditional economies of scale rationale. We show that this durable goods subsidization problem is due solely to the public firm's potential commitment problems with buyers. [source] Some remarks on characterization and application of stationary phases for RP-HPLC determination of biologically important compoundsBIOMEDICAL CHROMATOGRAPHY, Issue 1 2006Sylwia Kowalska Abstract Biologically active compounds such as vitamins, steroids, nucleosides, peptides and proteins play a very important role in coordinating living organism functions. Determination of those substances is indispensable in pathogenesis. Their complex structure and physico-chemical properties cause many analytical problems. Chromatography is the most common technique used in pharmaceutical and biomedical analysis. The interaction between analyte and stationary phase plays a major role in the separation process. The structure of the packing has a significant influence on the results of the separation process. Various types of spectroscopic techniques, such as nuclear magnetic resonance spectroscopy, infrared spectroscopy, fluorescence spectroscopy and photoacoustic spectroscopy can be useful tools for the characterization of packings. Surface area measurements, elemental analysis, thermal analysis and microcalorimetric measurements are also helpful in this field. Part of the paper contains a description of chromatographic tests used for the determination of column properties. The description of the possibilities of surface characterization is not complete, but is focused on the most popular techniques and practical chromatographic tests. All the presented methods made possible the design and quality control of a new generation stationary phases, which are the future of high-performance liquid chromatography. Copyright © 2005 John Wiley & Sons, Ltd. [source] Hydrogeological Characteristics of a Karst Mountainous Catchment in the Northwest of VietnamACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2001V. T. TAM Abstract This paper presents a preliminary assessment of the hydrogeological characteristics of a karst mountainous catchment, the Suoi Muoi River catchment, in the northwest of Vietnam. The catchment is located at 600,700 m a.s.l. and covers an area of 284 km. Exposed limestone occupies 32% of the total catchment area. Various types of assessments have been carried out, including geological and hydrogeological field surveys, cave surveys, dye-tracer tests, meteorological and surface water monitoring. Geological studies and cave surveys have identified the most important active cave/conduit systems within the catchment. Although these data are essential, they are insufficient to make a comprehensive appraisal of the hydrologic nature of the catchment under interest. An attempt was made to calculate a global water balance of the catchment, based on short-term (15 months) meteorological and streamflow records. The results show that, despite the existence of a number of substantial cavern conduit systems, the groundwater system of the catchment is governed by the fracture/fissure matrix. The cavern conduit systems only collect groundwater from the adjacent fracture matrix and/or connect topographically isolated surface watercourses. The groundwater storage of the cavern conduit systems appears to be regionally insignificant in comparison with the governed fracture matrix groundwater system. [source] The "Borrowing Hydrogen Strategy" by Supported Ruthenium Hydroxide Catalysts: Synthetic Scope of Symmetrically and Unsymmetrically Substituted AminesCHEMISTRY - A EUROPEAN JOURNAL, Issue 24 2010Kazuya Yamaguchi Dr. Abstract The N -alkylation of ammonia (or its surrogates, such as urea, NH4HCO3, and (NH4)2CO3) and amines with alcohols, including primary and secondary alcohols, was efficiently promoted under anaerobic conditions by the easily prepared and inexpensive supported ruthenium hydroxide catalyst Ru(OH)x/TiO2. Various types of symmetrically and unsymmetrically substituted "tertiary" amines could be synthesized by the N -alkylation of ammonia (or its surrogates) and amines with "primary" alcohols. On the other hand, the N -alkylation of ammonia surrogates (i.e., urea and NH4HCO3) with "secondary" alcohols selectively produced the corresponding symmetrically substituted "secondary" amines, even in the presence of excess amounts of alcohols, which is likely due to the steric hindrance of the secondary alcohols and/or secondary amines produced. Under aerobic conditions, nitriles could be synthesized directly from alcohols and ammonia surrogates. The observed catalysis for the present N -alkylation reactions was intrinsically heterogeneous, and the retrieved catalyst could be reused without any significant loss of catalytic performance. The present catalytic transformation would proceed through consecutive N -alkylation reactions, in which alcohols act as alkylating reagents. On the basis of deuterium-labeling experiments, the formation of the ruthenium dihydride species is suggested during the N -alkylation reactions. [source] Photosensitization and the Photocurrent Switching Effect in Nanocrystalline Titanium Dioxide Functionalized with Iron(II) Complexes: A Comparative StudyCHEMISTRY - A EUROPEAN JOURNAL, Issue 20 2007Wojciech Macyk Dr. Abstract Selected iron(II) complexes (ferrocene, ferrocenylboronic acid, hexacyanoferrate(II)) have been used as photosensitizers of titanium dioxide. Various types of electronic interactions between the surface complex and the semiconducting support are reflected in different yields of photocurrent generated upon visible-light irradiation and different efficiencies of the photosensitization effect. The studied systems, showing the photocurrent switching upon changes of electrode potential and energy of photons (the PEPS effect), are good models of simple photoelectrochemical logic devices. The mechanism of photosensitization and photocurrent switching is discussed with respect to the type of surface-complex,support interaction. Quantum-mechanical calculations support the proposed mechanisms. Wybrane kompleksy ,elaza(II) (ferrocen, kwas ferrocenyloboronowy i heksacyjano,elazian(II)) zosta,y u,yte jako fotosensybilizatory dwutlenku tytanu. Ró,ne typy oddzia,ywa, elektronowych pomi,dzy kompleksami powierzchniowymi a pod,o,em pó,przewodnikowym znajduj, odbicie w ró,nych wydajno,ciach generacji fotopr,du i ró,nym stopniu fotosensybilizacji materia,ów na ,wiat,o widzialne. Wszystkie badane uk,ady wykazuj, efekt fotoelektrochemicznego prze,,czenia fotopr,du na skutek zmian potencja,u fotoelektrody i zmian d,ugo,ci fali ,wiat,a padaj,cego (efekt PEPS), dlatego te, stanowi, bardzo dobre modele prostych prze,,czników fotoelektrochemicznych. Niniejsza praca szczegó,owo okre,la mechanizm fotosensybilizacji i prze,,czenia fotopr,du na podstawie analizy oddzia,ywa, pomi,dzy kompleksem a powierzchni, pó,przewodnika. Obliczenia kwantowo-mechaniczne potwierdzaj, postulowany mechanizm. [source] Bifunctional-Thiourea-Catalyzed Diastereo- and Enantioselective Aza-Henry ReactionCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2006Xuenong Xu Dr. Abstract Bifunctional thiourea 1,a catalyzes aza-Henry reaction of nitroalkanes with N -Boc-imines to give syn -,-nitroamines with good to high diastereo- and enantioselectivity. Apart from the catalyst, the reaction requires no additional reagents such as a Lewis acid or a Lewis base. The N-protecting groups of the imines have a determining effect on the chirality of the products, that is, the reaction of N -Boc-imines gives R adducts as major products, whereas the same reaction of N -phosphonoylimines furnishes the corresponding S adducts. Various types of nitroalkanes bearing aryl, alcohol, ether, and ester groups can be used as nucleophiles, providing access to a wide range of useful chiral building blocks in good yield and high enantiomeric excess. Synthetic versatility of the addition products is demonstrated by the transformation to chiral piperidine derivatives such as CP-99,994. [source] Malformation of True Bug (Heteroptera): a Phenotype Field Study on the Possible Influence of Artificial Low-Level RadioactivityCHEMISTRY & BIODIVERSITY, Issue 4 2008Cornelia Hesse-Honegger Abstract The results of extensive field studies on the malformation of Western European true bugs (Heteroptera) are reviewed. More than 16,000 individuals were collected over two decades, and subjected to detailed visual inspection. Various types of disturbances were found and illustrated in detail. Depending on country, region, as well as local influences, severe disturbances and high degrees of malformation were noticed, especially in the sphere of nuclear-power installations in Switzerland (Aargau), France (La Hague), and Germany (Gundremmingen). Malformation reached values as high as 22 and 30% for morphological (MD) and total disturbance (TD), respectively. This is far above the values expected for natural populations (ca. 1%) or those determined for true bugs living in biotopes considered as relatively ,intact' (1,3%). A detailed chi-square test of the malformation data obtained for 650 true bugs from 13 collection sites near the nuclear-reprocessing plant La Hague showed a highly significant correlation (p=0.003) between malformation and wind exposure/local topography. Similar observations were made for other study sites. Currently, our data are best rationalized by assuming a direct influence between the release of anthropogenic radionuclides such as tritium (3H), carbon-14 (14C), or iodine-131 (131I), constantly emitted by nuclear-power and nuclear-reprocessing plants, as well as by Chernobyl and bomb-testing fallout, which is rich in caesium-137 (137Cs) and other long-lived noxious isotopes that have entered the food chain. The present work supports the growing evidence that low-level radiation, especially in the form of randomly scattered ,hot' , - and , -particles, mainly transported via aerosols, puts a heavy burden on the biosphere in general, and on true bugs in particular. These insects could, thus, serve as sensitive ,bio-indicators' for future studies. [source] Late results of treatment of anal fistulasCOLORECTAL DISEASE, Issue 2 2007A. Sygut Abstract Objective, The aim of this paper was to analyse the results of treatment of anal fistulas retrospectively. Methods, Between 1992 and 2004, 407 patients were operated on for perianal fistula. In the follow-up period, 107 patients were lost, so 300 patients were analysed in the study. The mean follow-up time was 4.2 years. Analysed parameters included: types of surgical procedures in different kinds of fistulas and postoperative complications. Various types of surgical procedures and their effectiveness were described. Late results were assessed taking into account healing time, duration of sick leave, recurrence rate and incidence of anal sphincter dysfunction. Severity of gas and stool incontinence was assessed according to the Cleveland Clinic Incontinence Score. Results, In our study, subcutaneous fistula was diagnosed in 23.3%, inter-sphincteric in 18%, trans-sphincteric in 37.7%, supra-sphincteric in 16% and extra-sphincteric in 5% of patients. Single-tract fistulas were present in 88.7% and multi-tract fistulas were present in 11.3%. Overall, 242 patients had primary fistulas and 58 patients had recurrent fistulas. The most frequently performed procedures were cutting seton (139 patients) and radical fistulectomy (104 patients). Recurrent fistulas developed in 14.3%. Postoperative gas and/or stool incontinence was noticed in 10.7%. The recurrence rate was 5.4% in patients with primary fistula and in 51.7% patients presenting with a recurrent fistula. Gas and stool incontinence developed in 3.7% of patients with primary fistulas and in 39.7% of patients presenting with recurrent fistulas. Recurrence rate was 12% in the patients of single-tract fistulas and 32.4% in the patients of multi-tract fistulas. Postoperative gas and/or stool incontinence occurred in 8.3% of patients of single-tract fistulas and in 29.4% of patients of multi-tract fistulas. Conclusions, The complication rate was 10-fold higher in patients presenting with a recurrent fistula than in those with primary fistulas and threefold higher in patients with multi-tract fistulas than in those with single-tract fistulas. [source] Image-based modeling of 3D objects with curved surfacesCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 2 2008Man Hee Lee Abstract This paper addresses an image-based method for modeling 3D objects with curved surfaces based on the non-uniform rational B-splines (NURBS) representation. The user fits the feature curves on a few calibrated images with 2D NURBS curves using the interactive user interface. Then, 3D NURBS curves are constructed by stereo reconstruction of the corresponding feature curves. Using these as building blocks, NURBS surfaces are reconstructed by the known surface building methods including bilinear surfaces, ruled surfaces, generalized cylinders, and surfaces of revolution. In addition to them, we also employ various advanced techniques, including skinned surfaces, swept surfaces, and boundary patches. Based on these surface modeling techniques, it is possible to build various types of 3D shape models with textured curved surfaces without much effort. Copyright © 2007 John Wiley & Sons, Ltd. [source] Projected slabs: approximation of perspective projection and error analysis,COMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 5 2001A. Vilanova Bartrolí Abstract Virtual endoscopy is a promising medical application for volume-rendering techniques where perspective projection is mandatory. Most of the acceleration techniques for direct volume rendering use parallel projection. This paper presents an algorithm to approximate perspective volume rendering using parallel projected slabs. The introduced error due to the approximation is investigated. An analytical study of the maximum and average error is made. This method is applied to VolumePro 500. Based on the error analysis, the basic algorithm is improved. This improvement increases the frame rate, keeping the global maximum error bounded. The usability of the algorithm is shown through the virtual endoscopic investigation of various types of medical data sets. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||