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Bimodal Distribution (bimodal + distribution)
Selected AbstractsDenaturant sensitive regions in creatine kinase identified by hydrogen/deuterium exchangeRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2005Hortense Mazon The GdmHCl-induced unfolding of creatine kinase (CK) has been studied by hydrogen/deuterium (H/D) exchange combined with mass spectrometry. MM-CK unfolded for various periods in different denaturant concentrations was pulsed-labeled with deuterium to identify different conformational intermediate states. For all denaturation times or GdmHCl concentrations, we observed variable proportions of only two species. The low-mass envelope of isotope peaks corresponds to a species that has gained about 10 deuteriums more than native CK, and the high-mass envelope to a completely deuterated species. To localize precisely the unfolded regions in the states highly populated during denaturation, the protein was digested with two proteases (pepsin and type XIII protease) after H/D exchange and rapid quenching of the reaction. The two sets of fragments obtained were analyzed by liquid chromatography coupled to mass spectrometry to determine the deuterium level in each fragment. Bimodal distributions of deuterium were found for most peptides, indicating that these regions were either folded or unfolded. This behavior is consistent with cooperative, localized unfolding. However, we observed a monomodal distribution of deuterium in two regions (1,12 and 162,186). We conclude that the increment of mass observed in the low-mass species of the intact protein (+10,Da) has its origin in these two segments. These regions, which are very sensitive to low GdmHCl concentrations, are involved in the monomer,monomer interface of CK and their perturbation is likely to weaken the dimeric structure. At higher denaturant concentration, this would induce dissociation of the dimer. Copyright © 2005 John Wiley & Sons, Ltd. [source] Particle path length distributions in meandering gravel-bed streams: results from physical modelsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2003Richard S. Pyrce Abstract In gravel-bed rivers with well-de,ned pool,bar morphology, the path length of transported bed particles must be, at least during ,channel-forming' ,ows, equal to the length scale of the morphology. This is the basis for some methods for estimating bed material transport rates. However, previous data, especially from ,eld tests, are often strongly positively skewed with mean much shorter than the pool,bar spacing. One possible explanation is that positively skewed distributions occur only in channels lacking distinct pool,bar topography or only at lower discharges in pool,bar channels. A series of ,ume experiments using ,uorescent tracers was used to measure path length distributions in low-sinuosity meandering channels to assess the relation with channel morphology and ,ow conditions. At channel-forming ,ows, 55 to 75 per cent of the tracer grains were deposited on the ,rst point bar downstream of the point of tracer input, with 15 per cent passing beyond the ,rst bar. Path length distributions are symmetrical with mean equal to the pool,bar spacing and can be described with a Cauchy distribution. In some cases there was a secondary mode close to the point of tracer introduction; this bimodal distribution ,ts a combined gamma,Cauchy distribution. Only when discharge was reduced below the channel-forming ,ow were frequency distributions unimodal and positively skewed with no relation to the pool,bar spacing. Thus, path length distributions become more symmetrical, and mean path length increases to coincide with pool,bar spacing, as ,ow approaches channel-forming conditions. This is a substantial modi,cation of existing models of particle transfer in gravel-bed rivers. Copyright © 2003 John Wiley & Sons, Ltd. [source] Systematic Review and Meta-analysis of Incidence Studies of Epilepsy and Unprovoked SeizuresEPILEPSIA, Issue 11 2002Irene A. W. Kotsopoulos Summary: ,Purpose: To evaluate the methodology of incidence studies of epilepsy and unprovoked seizures and to assess the value of their findings by summarizing their results. Methods: A Medline literature search from January 1966 to December 1999 was conducted. In each selected study, key methodologic items such as case definition and study design were evaluated. Furthermore, a quantitative meta-analysis of the incidence data was performed. Results: Forty incidence studies met the inclusion criteria. There was considerable heterogeneity in study methodology, and the methodologic quality score was generally low. The median incidence rate of epilepsy and unprovoked seizures was 47.4 and 56 per 100,000, respectively. The age-specific incidence of epilepsy was high in those aged 60 years or older, but was highest in childhood. Males had a slightly higher incidence of epilepsy (median, 50.7/100,000) than did females (median, 46.2/100,000), and partial seizures seemed to occur more often than generalized seizures. Developing countries had a higher incidence rate of epilepsy (median, 68.7/100,000) than did industrialized countries (median, 43.4/100,000). Similar results were found for unprovoked seizures. The incidence of epilepsy over time appears to decrease in children, whereas it increases in the elderly. Conclusions: The age-specific incidence of epilepsy showed a bimodal distribution with the highest peak in childhood. No definitive conclusions could be reached for the incidence of unprovoked seizures and other specific incidence rates of epilepsy. More incidence studies with an adequate study methodology are needed to explore geographic variations and time trends of the incidence of epilepsy and unprovoked seizures. [source] A systematic review of the epidemiology of status epilepticusEUROPEAN JOURNAL OF NEUROLOGY, Issue 12 2004R. F. M. Chin Population-based data on the incidence, aetiology, and mortality associated with status epilepticus (SE) are required to develop preventative strategies for SE. Through a systematic review, we aimed to assess the methodological quality as well as similarities, and differences between available population based studies in order to arrive at conclusions on the epidemiology of SE. All population-based studies where primary outcome was incidence, aetiology or mortality of SE were identified through a systematic search and synthesized. Methodological quality of studies were independently rated by two examiners using a unique scoring system. Seven population-based projects on SE yielding nine published reports and five abstracts were reviewed. Quality scores were in the range of 19,34 with a possible maximum of 40 (kappa scores 0.67,1.0). The incidence of SE has a bimodal distribution with peaks in children aged less than a year and the elderly. Most SE were acute symptomatic. Short-term mortality was 7.6,22% and long-term mortality was 43%. Age and aetiology were the major determinants of mortality. There are few population-based studies on SE but most are of good quality. Most studies are primarily or exclusively based on adult populations. There is limited information on the association of ethnicity and socio-economic status and SE. [source] Analysis of the variable charge of two organic soils by means of the NICA-Donnan modelEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2007B. Vasiliadis Summary We have tested to see if the generic set of NICA-Donnan model parameters, used to describe isolated humic substances, can also describe soil humic substances in situ. A potentiometric back-titration technique was used to determine the variable surface charge of two organic peat soils at three different ionic strengths. The non-ideal, competitive-adsorption NICA-Donnan model was used to simulate the surface charge, by assuming a bimodal distribution of H+ affinity on the soil solid phase. The model provided an excellent fit to the experimental data. The Donnan volume, VD, varied slightly with ionic strength, although the variation was less than for humic substances in solution. The values obtained for the parameters that define the affinity distributions, the intrinsic proton binding constant (log Kiint) and the heterogeneity of the site (mi), were similar to those observed for isolated soil humic acids. The abundance of carboxylic groups in the whole soil represented 30% of the typical value for isolated soil humic acids. The composition of the organic matter of the whole soils, obtained by 13C CPMAS NMR, was comparable to the characteristic composition of soil humic acids. [source] The Clinical Implications of Cumulative Right Ventricular Pacing in the Multicenter Automatic Defibrillator Trial IIJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 4 2005JONATHAN S. STEINBERG M.D. Introduction: This study was designed to assess whether right ventricular pacing in the implantable cardioverter defibrillator (ICD) arm of the Multicenter Automatic Defibrillator Implantation Trial (MADIT) II was associated with an unfavorable outcome. Methods and Results: Data on the number of ventricular paced beats were available in 567 (76%) of 742 MADIT II patients with ICDs. The number of ventricular paced beats over the total number of beats showed a bimodal distribution with patients being predominantly paced or nonpaced. Therefore, patients were dichotomized at 0,50% and 51,100% of cumulative pacing with median pacing rate 0.2% and 95.6%, respectively. Endpoints included new or worsening heart failure, appropriate ICD therapy for VT/VF, and the combined endpoint of heart failure or death. Clinical features associated with frequent ventricular pacing included age ,65 years, advanced NYHA heart failure class, LVEF < 0.25, first degree AV and bundle branch block, and amiodarone use. During follow-up, 119 patients (21%) had new or worsened heart failure, 130 (23%) had new or worsened heart failure or death, and 142 (25%) had appropriate therapy for VT/VF. In comparison to patients with infrequent pacing, those with frequent pacing had significantly higher risk of new or worsened heart failure (hazard ratio = 1.93; P = 0.002) and VT/VF requiring ICD therapy (HR = 1.50; P = 0.02). Conclusions: Patients in MADIT II who were predominantly paced had a higher rate of new or worsened heart failure and were more likely to receive therapy for VT/VF. These results suggest the deleterious consequences of RV pacing, particularly in the setting of severe LV dysfunction. [source] Ecological gradients, subdivisions and terminology of north-west European miresJOURNAL OF ECOLOGY, Issue 2 2000B. D. Wheeler Summary 1,The historical development of mire ecology and terminology is reviewed in relation to evolving concepts and perceptions, and the diverse schools and traditions of vegetation and habitat description and research. 2,Most ecological and floristic variation within north-west European mire vegetation is accounted for by three ecological gradients: the acid base-poor vs. neutral, base- and bicarbonate-rich gradient; the gradient in fertility related to availability of the limiting nutrient elements N and P; and the water level gradient. Effects of salinity and the spring,flush,fen gradients are of more local significance, usually easily recognized. Land use is an important additional factor. 3,The mineral-soil-water limit between ombrotrophic and minerotrophically influenced sites is not sharp, and cannot be related to consistent differences in either vegetation or water chemistry. It should be abandoned as a general main division within mires. 4,The most important natural division is between ,bog', with pH generally < 5.0, low Ca2+, and Cl, and SO42, as the main inorganic anions, typically dominated by sphagna, ericoids and calcifuge Cyperaceae, and ,fen', with pH generally > 6.0, high Ca2+ and HCO3,, vegetation rich in dicotyledonous herbs and ,brown mosses'. This division is reflected in a bimodal distribution of pH. 5,The terms oligotrophic, mesotrophic and eutrophic should refer only to nutrient richness (fertility, mainly N and P), not to base richness (metallic cations and pH). 6,It is recommended that ,mire' should embrace both wetlands on peat and related communities on mineral soils, that ,bog' (unqualified) should encompass both ombrotrophic and weakly minerotrophic mires, including ,bog woodland', and that ,fen' should be restricted to base-rich mires but include both herbaceous and wooded vegetation (,fen carr'). 7,Definitions are given for a range of broadly defined categories that should cover most vegetation types commonly encountered. The relation of these to British national vegetation classification types and to major units in European phytosociology is outlined. [source] High resolution analysis of mating systems: inbreeding in natural populations of Pinus radiataJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2002C. Vogl Pinus radiata has a history of population bottlenecks and is currently restricted to five relatively small populations, three in mainland California, and two on islands off the coast of Baja California. Using highly polymorphic microsatellite markers and a newly developed statistical approach, we were able to estimate individual inbreeding coefficients and can thus analyse the mating system with high resolution. We find a bimodal distribution of inbreeding coefficients: most individuals result from selfing whereas few (in the mainland populations) to a modest number (in the island populations) are likely selfed. In most other pine species and presumably in the ancestral P. radiata population, occurrence of mature selfed individuals would be impossible because of the high genetic load. We therefore conclude that inbreeding depression has been purged in P. radiata and that the mating system has changed as a consequence. [source] Intracellular uptake and trafficking of Pluronic micelles in drug-sensitive and MDR cells: Effect on the intracellular drug localizationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2002Natalya Rapoport Abstract The intracellular uptake and localization of a fluorescently labeled Pluronic P-105 in HL-60 leukemia cells and in A2780 drug-sensitive and A2780/ADR MDR ovarian carcinoma cells were characterized by flow cytometry and fluorescence microscopy. Pluronic P-105 molecules were labeled with a pH-sensitive fluorescent label, 5-(and 6-)carboxy-2,7,-dichlorofluorescein. The fluorescence intensity of labeled Pluronic was about twofold higher at pH 7.4 than at pH 5.5. At Pluronic concentrations exceeding the critical micelle concentration (cmc), flow cytometry histograms manifested bimodal distribution of cell fluorescence for all types of cells. Cell population characterized by higher fluorescence intensity presumably resulted from Pluronic transfer from the acidic environment of cytoplasmic vesicles (endosomes or lysosomes) into the neutral environment of the cytoplasm and cell nuclei, which suggested the permeabilization of the membranes of acidic vesicle by Pluronic molecules. For the MDR cells, the bimodal distribution of cell fluorescence was already observed at very low Pluronic concentrations in the incubation medium (i.e., below the cmc). The data suggest that the membranes of acidic vesicles of MDR cells are more susceptible to the action of polymeric surfactants than those of drug-sensitive cells. Permeabilization of acidic vesicles had a dramatic effect on the intracellular trafficking of drugs: when delivered in PBS, the anthracyclin drug ruboxyl (Rb) sequestered in cytoplasmic vesicles and was excluded from cell nuclei; however, when delivered in Pluronic micelles, drug accumulated in cell nuclei. Drug uptake from/with Pluronic micelles was substantially enhanced by ultrasound. These findings suggest that the nuclear accumulation of drugs internalized via fluid-phase endocytosis can be enhanced by the application of Pluronic micelles and can be further augmented by ultrasonic irradiation. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:157,170, 2002 [source] Alternating copolymerization of carbon dioxide and epoxide catalyzed by an aluminum Schiff base,ammonium salt systemJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2005Hiroshi Sugimoto Abstract The alternating copolymerization of carbon dioxide (CO2) and cyclohexene oxide (CHO) with an aluminum Schiff base complex in conjunction with an appropriate additive as a novel initiator is demonstrated. A typical example is the copolymerization of CO2 and CHO with the (Salophen)AlMe (1a),tetraethylammonium acetate (Et4NOAc) system. When a mixture of the 1a,Et4NOAc system and CHO was pressurized by CO2 (50 atm) at 80 °C in CH2Cl2, the copolymerization of CO2 and CHO took place smoothly and produced a high polymer yield in 24 h. From the IR and NMR spectra, the product was characterized to be a copolymer of CO2 and CHO with an almost perfect alternating structure. The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis indicated that an unfavorable reaction between Et4NOAc and CH2Cl2 and a possible chain-transfer reaction with concomitant water occurred, and this resulted in the bimodal distribution of the obtained copolymer. With carefully predried reagents and apparatus, the alternating copolymerization in toluene gave a copolymer with a unimodal and narrower molecular weight distribution. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4172,4186, 2005 [source] Bioavailable cadmium during the bioremediation of phenanthrene-contaminated soils using the diffusive gradients in thin-film techniqueLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2006M.A. Amezcua-Allieri Abstract Aims:, To study the impact of fungal bioremediation of phenanthrene on trace cadmium solid-solution fluxes and solution phase concentration. Methods and Results:, The bioremediation of phenanthrene in soils was performed using the fungus Penicillium frequentans. Metal behaviour was evaluated by the techniques of diffusive gradient in thin-films (DGT) and filtration. Fluxes of cadmium (Cd) show a significant (P < 0·002) increase after the start of bioremediation, indicating that the bioremediation process itself releases significant amount of Cd into solution from the soil solid-phase. Unlike DGT devices, the solution concentration from filtration shows a clear bimodal distribution. We postulate that the initial action of the fungi is most likely to breakdown the surface of the solid phase to smaller, ,solution-phase' material (<0·45 ,m) leading to a peak in Cd concentration in solution. Conclusions:, Phenanthrene removal from soils by bioremediation ironically results in the mobilization of another toxic pollutant (Cd). Significance and Impact of the Study:, Bioremediation of organic pollutants in contaminated soil will likely lead to large increases in the mobilization of toxic metals, increasing metal bio-uptake and incorporation into the wider food chain. Bioremediation strategies need to account for this behaviour and further research is required both to understand the generality of this behaviour and the operative mechanisms. [source] Spinodal Decomposition in Ternary Systems with Significantly Different Component DiffusivitiesMACROMOLECULAR THEORY AND SIMULATIONS, Issue 6 2007Abdulrahman A. Alfarraj Abstract A numerical method for simulating spinodal decomposition in ternary systems with order-of-magnitude differences in diffusion coefficients is presented. The method has been partially verified by molecular dynamic simulations and gives results equivalent to the standard technique when the diffusivities are equal. A two-dimensional simulation of an asymmetric polymer/polymer/polymer system reproduces an experimentally observed bimodal distribution of dispersed-phase particle sizes. The ripening exponent for the larger particles is near the expected value of 0.33, but that for the smaller particles is only about 0.1. The method was also used for a polymer/polymer/solvent system. [source] Reduced introgression of the Y chromosome between subspecies of the European rabbit (Oryctolagus cuniculus) in the Iberian PeninsulaMOLECULAR ECOLOGY, Issue 20 2008A. GERALDES Abstract The role of the Y chromosome in speciation is unclear. Hybrid zones provide natural arenas for studying speciation, as differential introgression of markers may reveal selection acting against incompatibilities. Two subspecies of the European rabbit (Oryctolagus cuniculus) form a hybrid zone in the Iberian Peninsula. Previous work on mitochondrial DNA (mtDNA), Y- and X-linked loci revealed the existence of two divergent lineages in the rabbit genome and that these lineages are largely subspecies-specific for mtDNA and two X-linked loci. Here we investigated the geographic distribution of the two Y chromosome lineages by genotyping two diagnostic single nucleotide polymorphisms in a sample of 353 male rabbits representing both subspecies, and found that Y chromosome lineages are also largely subspecies-specific. We then sequenced three autosomal loci and discovered considerable variation in levels of differentiation at these loci. Finally, we compared estimates of population differentiation between rabbit subspecies at 26 markers and found a surprising bimodal distribution of FST values. The vast majority of loci showed little or no differentiation between rabbit subspecies while a few loci, including the SRY gene, showed little or no introgression across the hybrid zone. Estimates of population differentiation for the Y chromosome were surprisingly high given that there is male-biased dispersal in rabbits. Taken together, these data indicate that there is a clear dichotomy in the rabbit genome and that some loci remain highly differentiated despite extensive gene flow following secondary contact. [source] Bimodal skin reactivity to histamine in atopic children in Singapore: influence of specific sensitizationsPEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 6 2004Mona Iancovici Kidon Histamine skin prick test (SPT) is used as the ,golden standard' for positive control in in vivo immediate type hypersensitivity testing. The skin reactivity to histamine can, however, be modulated by a bevy of extraneous factors. We aimed to define whether histamine skin reactivity in atopic children in Singapore is influenced by age, ethnic origin, gender, environmental exposure or specific sensitization patterns. A retrospective analysis of children, with specific aeroallergen sensitization (as measured by at least one allergen-specific SPT with a wheal size >3 mm compared with the negative control) from the outpatient speciality clinic of the KK Children's Hospital, during 06/2002,06/2003. A total of 315 patients were included, 235 (75%) were males, 252 (80%) were Chinese, age mean was 7.7 yr (range: 2,15). Patients were referred to the SPT with a diagnosis of one or more of: allergic rhinitis 287 (91%), asthma 112 (36%) or atopic dermatitis 60 (19%). The mean histamine response showed a bimodal distribution, independent of age, ethnic origin, gender or phenotypical expression of allergic disease. Histamine skin reactivity was higher in atopic patients with polysensitization (mean 5.0 mm vs. 2.9 mm in monosensitized patients, p < 0.001), and in patients with mould sensitization (mean 5.1 mm vs. 3.3 mm in patient not sensitized to moulds, p < 0.001). The presence of passive smoking increased the likelihood of a diminished histamine skin response. Histamine skin response data strongly suggested the presence of two heterogeneous subpopulations. Children with polysensitization and mould sensitization were more likely to show a large significant histamine response, whereas children with passive smoke exposure, showed a diminished skin reactivity to histamine. [source] Cowpea weevil flights to a point source of female sex pheromone: analyses of flight tracks at three wind speedsPHYSIOLOGICAL ENTOMOLOGY, Issue 2 2006L. P. S. Kuenen Abstract., Two-day-old male cowpea weevils, Callosobruchus maculatus, fly upwind to a point source of female sex pheromone at three wind speeds. All beetles initiating flight along the pheromone plume make contact with the pheromone source. Analysis of digitized flight tracks indicates that C. maculatus males respond similarly to moths tested at several wind speeds. Beetles' mean net upwind speeds and speeds along their track are similar (P > 0.05) across wind speeds, whereas airspeeds increase (P < 0.01) with increasing wind speed. Beetles adjust their course angles to fly more directly upwind in higher wind speeds, whereas track angles are almost identical at each wind speed. The zigzag flight paths are generally narrow compared with most moth flight tracks and interturn distances are similar (P > 0.05) at the wind speeds employed. The frequency of these counterturns across the wind line is almost constant regardless of wind speed, and there is little variation between individuals. The upwind flight tracks are more directly upwind than those typically seen for male moths flying upwind toward sex pheromone sources. Male moths typically produce a bimodal distribution of track angles to the left and right of the windline, whereas C. maculatus males' track angles are centred about 0°. Preliminary examination of two other beetle species indicates that they fly upwind in a similar fashion. [source] Inheritance of resistance to carboxylic acid amide (CAA) fungicides in Plasmopara viticolaPLANT PATHOLOGY, Issue 2 2007U. Gisi Mandipropamid is a new mandelic acid amide fungicide expressing high activity against foliar infecting oomycetes, including the grapevine downy mildew, Plasmopara viticola. Because cross-resistance with the valinamide fungicides iprovalicarb and benthiavalicarb and the cinnamic acid amide fungicides dimethomorph and flumorph was postulated, all five compounds are classified as carboxylic acid amide (CAA) fungicides. To support this classification, cross-resistance among these compounds with field isolates and the segregation of resistance in F1 and F2 progeny of P. viticola were evaluated. A bimodal distribution of sensitivity in field isolates and cross-resistance among all CAAs for the vast majority of isolates were detected. Crosses between sensitive (s) and CAA-resistant (r) isolates of opposite mating types, P1 and P2, yielded abundant oospores. All F1 -progeny isolates were sensitive to CAAs (s:r segregation 1:0), whereas in F2 progeny segregation of about 9:1 (s:r) was observed suggesting that resistance to CAA fungicides is controlled by two recessive nuclear genes. Mating type segregated in a ratio P1:P2 of c. 2:1 in F1 and 1:1 in F2 progeny. In the same crosses, resistance to the phenylamide fungicide mefenoxam segregated in a ratio of c. 1:3:2 (sensitive:intermediate:resistant), reflecting the monogenic, semidominant nature of resistance. The risk of resistance in P. viticola was classified as high for phenylamide and moderate for CAA fungicides. This is the first report on the inheritance of phenotypic traits in P. viticola. [source] Variations in size structure, growth and reproduction in Japanese plantain (Plantago asiatica L.) between exposed and shaded populationsPLANT SPECIES BIOLOGY, Issue 1 2001Tsuyoshi Kobayashi Abstract Plantago asiatica is a perennial herb that is distributed over a wide range of east Eurasia. The population structure, growth and reproduction in exposed (E-) and shaded (S-) populations of P. asiatica were examined in the Kanto District of eastern Japan. In both populations, the plant size structure showed a bimodal distribution during spring to early summer, in which the two modes corresponded to smaller seedlings and larger overwintered plants, respectively. In autumn, this distribution became unimodal due to seedling growth. However, this change occurred later in the S-population because of suppressed growth in the seedlings. In the S-population, flowering also began later in the growing season and the threshold plant size for flowering was larger than that of the E-population. Biomass allocation to the rhizomes was greater in autumn in the reproductive plants of the S-population. Growth and biomass allocation in plants grown from seeds collected from each population were compared under phytotron conditions. Near a saturated photon flux density, E-population plants had a higher relative growth rate than S-population plants. Therefore, E-population plants should allocate resources to reproductive organs sooner. Shaded population plants were not vigorous in their growth and reproduction. Seed size (dry weight per grain) was significantly greater in the S-population than in the E-population, both in the field and under phytotron conditions. These results suggest that ecotypic differentiation in life-history strategies, which is mainly due to light availability, occurs among local P. asiatica populations. The effects of severe trampling on early reproduction in the E-population are also discussed. [source] Spatial and temporal evolution of the photo initiation rate for thick polymer systems illuminated on both sidesPOLYMER INTERNATIONAL, Issue 10 2005Nicole Stephenson Abstract Photopolymerizations of thick systems are inherently non-uniform and much more complex than polymerizations of films and coatings. This contribution presents a mathematical description of the evolution of the photoinitiation rate profile for a thick photopolymerization system illuminated on two sides. Simulation results revealed that when two lamps of equal intensity are used, the spatial and temporal evolution of the photoinitiation rate profile follows a characteristic progression from a bimodal distribution to a unimodal shape with a maximum in the center of the sample. The addition of a second light source can lead to an initiation profile that is more uniform throughout the sample. System variables such as the initiator concentration, molar absorptivity and monomer absorptivity determine how the photoinitiation rate profile evolves. For example, increasing initiator concentration results in sharper initiation fronts which move through the sample more slowly. A reflective boundary condition, a special case of two-sided illumination using only one lamp, was found to enhance the initiation rate and uniformity for some reaction systems. This model provides the fundamental understanding needed to ensure proper selection of reaction components for effective photoinitiation in thick systems, including the possibility of a second light source as an additional design variable. Copyright © 2005 Society of Chemical Industry [source] Tryptophanyl fluorescence lifetime distribution of hyperthermophilic ,-glycosidase from molecular dynamics simulation: A comparison with the experimental dataPROTEIN SCIENCE, Issue 9 2000Ettore Bismuto Abstract A molecular dynamics simulation approach has been utilized to understand the unusual fluorescence emission decay observed for ,-glycosidase from the hyperthermophilic bacterium Solfolobus sulfataricus (S,gly), a tetrameric enzyme containing 17 tryptophanyl residues for each subunit. The tryptophanyl emission decay of (S,gly) results from a bimodal distribution of fluorescence lifetimes with a short-lived component centered at 2.5 ns and a long-lived one at 7.4 ns Bismuto E, Nucci R, Rossi M, Irace G, 1999, Proteins 27:71,79). From the examination of the trajectories of the side chains capable of causing intramolecular quenching for each tryptophan microenvironment and using a modified Stern,Volmer model for the emission quenching processes, we calculated the fluorescence lifetime for each tryptophanyl residue of S,gly at two different temperatures, i.e., 300 and 365 K. The highest temperature was chosen because in this condition S,lgy evidences a maximum in its catalytic activity and is stable for a very long time. The calculated lifetime distributions overlap those experimentally determined. Moreover, the majority of trytptophanyl residues having longer lifetimes correspond to those originally identified by inspection of the crystallographic structure. The tryptophanyl lifetimes appear to be a complex function of several variables, such as microenvironment viscosity, solvent accessibility, the chemical structure of quencher side chains, and side-chain dynamics. The lifetime calculation by MD simulation can be used to validate a predicted structure by comparing the theoretical data with the experimental fluorescence decay results. [source] Sarcoidosis in Singapore: Epidemiology, clinical presentation and ethnic differencesRESPIROLOGY, Issue 3 2007Devanand ANANTHAM Background and objectives: The aim of this study is to better understand the epidemiological and clinical features of patients with sarcoidosis in Singapore and to ascertain if ethnic differences exist. Methods: A review of hospital medical records from June 1998 to May 2004 to identify patients with sarcoidosis. Results: There were 59 patients with sarcoidosis identified (19 Chinese, 29 Asian Indian and 11 Malay). The estimated annual incidence of sarcoidosis in Singapore was 0.56 per 100 000. There was a significant difference between the observed and expected disease frequency in Chinese (32.2% vs 78.7%) and Indians (49.2% vs 6.0%, P < 0.005). A bimodal distribution of age at diagnosis was seen with peaks in the 30,39 years and 50,59 years age groups; 38.9% of cases were over the age of 50. Chinese patients were more likely to be asymptomatic (57.9%, P = 0.015) and less likely to have impaired spirometry (P = 0.013). Pulmonary sarcoid presented largely as stage 0 or stage 1 disease (74.4%). Overall mean spirometry was unimpaired and prognosis was good with 79.2% showing no radiological deterioration. There were no significant differences in organ involvement or treatment between ethnic groups. Conclusion: Sarcoidosis in Singapore is rare and the incidence differs between ethnic groups. Chinese appear to have a lower incidence and a less symptomatic presentation; Indians have a higher incidence and poorer clinical course. [source] ORIGINAL ARTICLE: How Should Data on Murine Spontaneous Abortion Rates be Expressed and Analyzed?AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 3 2008David A. Clark Problem, Spontaneous abortions in the CBA × DBA/2 model are normally reported as number of resorptions/total number of implantations (R/T), pooling data from individual mice. The significance of differences between groups has been determined using non-parametric statistics (e.g. chi-square or Fisher's Exact test) based on a priori predictions. Recently, it has been argued that medians with box plots should replace the accepted standard, but this deprives readers of data needed to verify P -values, and leads to inferences incompatible with biological and statistical reality. Method of study, Raw data on 173 individual CBA × DBA/2 matings were analyzed by median and mean, along with R/T data from 18 independent experiments containing 5,10 mice per group. Raw data from 19 CBA × BALB/c matings were similarly analyzed. Results, Individual CBA × DBA/2 mouse resorption rates showed a non-Gaussian distribution, but the mean and median differed by <0.5%. Resorption data from 6 and 12 independent pools of mice were normally distributed. Only the mean enabled a between-group P -value calculation. CBA × BALB/c matings gave a median of 0 and mean of 5.1%; the data were not normally distributed, but that was because of a bimodal distribution. One group of mice had 0 abortions, and the second a mean of 13.9% abortions, and the data from the latter group were normally distributed. Conclusion, Although it is possible to compare individual mice, and even individual implantation sites, in resorption (abortion) studies, as the relevant question is the significance of differences between treatment groups of mice, and reproducibility, the established classical method of reporting R/T should continue to be provided. In CBA × BALB/c matings, where abortion rates are low, using the median is misleading and may obscure the existence of two distinct populations. [source] Genetic relationship between Litopenaeus setiferus (L.) and L. schmitti (Burkenroad) determined by using 16S mitochondrial sequences and enzymatic analysisAQUACULTURE RESEARCH, Issue 12 2003L Arena Abstract Genetic differentiation and variability data of two populations of two species of shrimp (Litopenaeus setiferus (L.) and L. schmitti (Burkenroad)) have been obtained by electrophoretic analysis and by analysis of 16S mitochondrial DNA. Using eight polymorphic enzymes, the genetic distance (GD) between the two species was 0.165. The GD between L. setiferus populations was 0.0057 and between L. schmitti populations it was 0.0034. The greatest differentiation was found within, rather than between, populations, although the differentiation value between Mexican and Cuban populations varied in accordance with the geographic distance and ecological characteristic of each. We found a high similarity between these two species with a bimodal distribution of the loci with respect to genetic identity. The homology percentages for gene 16S fragments were compared with those from six different shrimp species (L. vannamei, L. stylirostris, Farfantepenaeus notialis, Metapeneopsis lamellata) and Artemia salina. Ninety-seven percent of identity was found by analysis of a 409 bp of 16S mitochondrial DNA. With these values a phylogenetic tree was made using parsimony criteria. The GDs obtained with this method confirm the classification proposed by Pérez-Farfante & Kensley (1997). [source] Clinical responses to tumor necrosis factor , antagonists do not show a bimodal distribution: Data from the Stockholm Tumor Necrosis Factor , Followup RegistryARTHRITIS & RHEUMATISM, Issue 6 2003Ronald F. van Vollenhoven Objective To study the distribution of clinical responses to treatment with the tumor necrosis factor , (TNF,) antagonists etanercept and infliximab, and in particular, to determine whether there is a biologically meaningful distinction between responders and nonresponders. Methods Among patients in the Stockholm TNF, Followup Registry, we analyzed the clinical responses to etanercept and infliximab, using the American College of Rheumatology (ACR) core set of outcome measures. For each parameter, the absolute change (value at baseline , current value) and the percentage change ([absolute change]/[value at baseline] × 100) from baseline were calculated. The results were plotted as histograms and inspected visually, and the distributions were statistically compared with computer-generated normal distributions. Results Absolute and relative changes in outcomes on the ACR core set of measures in 406 patients receiving etanercept or infliximab were studied. All but a few of these analyses yielded normal or somewhat skewed distributions. The statistical analyses did not detect any non-normal distributions, and visually, the distributions did not appear to be bimodal. Conclusion The clinical response to TNF, blockade displays a normal or skewed, but not bimodal, distribution. The frequently encountered perception that a clear distinction can be made between responders and nonresponders is not borne out. These relatively straightforward findings imply that the biologic mechanisms determining responsiveness to TNF, blockade are multifactorial and may also have important implications for regulatory guidelines pertaining to treatment with these biologic agents. [source] Sulphur abundances in halo stars from multiplet 3 at 1045 nm,ASTRONOMISCHE NACHRICHTEN, Issue 7 2010E. Caffau Abstract Sulphur is a volatile , -element which is not locked into dust grains in the interstellar medium (ISM). Hence, its abundance does not need to be corrected for dust depletion when comparing the ISM to the stellar atmospheres. The abundance of sulphur in the photosphere of metal-poor stars is a matter of debate: according to some authors, [S/Fe] versus [Fe/H] forms a plateau at low metallicity, while, according to other studies, there is a large scatter or perhaps a bimodal distribution. In metal-poor stars sulphur is detectable by its lines of multiplet 1 at 920 nm, but this range is heavily contaminated by telluric absorptions, and one line of the multiplet is blended by the hydrogen Paschen , line. We study the possibility of using multiplet 3 (at 1045 nm) for deriving the sulphur abundance because this range, now observable at the VLT with the infra-red spectrograph CRIRES, is little contaminated by telluric absorption and not affected by blends at least in metal-poor stars. We compare the abundances derived from multiplets 1 and 3, taking into account NLTE corrections and 3D effects. Here we present the results for a sample of four stars, although the scatter is less pronounced than in previous analysis, we cannot find a plateau in [S/Fe], and confirm the scatter of the sulphur abundance at low metallicity (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Craniopharyngioma: a review of long-term visual outcomeCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 3 2003Celia Chen MB BS MPHS Abstract Purpose: To assess the clinical presentation and long-term visual outcome in a series of patients with craniopharyn-gioma. Methods: Retrospective case review. Results: Thirty-six patients were reviewed, comprising 19 female patients and 17 male patients. The age range was 2,77 years with a bimodal distribution of 17 children (mean age 10 years) and 19 adults (mean age 47 years). Blurred vision was the most common visual complaint (23 cases, 64%) and headache the most frequent systemic complaint (19 cases, 53%). The average duration of systemic symptoms was 45 weeks compared to 10 weeks for visual symptoms. Deficits in visual acuity occurred in 13 patients (36%) and showed no significant change from initial presentation to final review. Sixteen patients (44%) had bitemporal hemianopia on presentation and pleomorphism (change from one type of visual field defect to another) occurred in 11 patients. Recurrence of tumour occurred in 15 patients (42%) and was more likely in children (59%) than adults (26%). The mean time period to recurrence was 7 years. The average follow-up period for all cases was 10 years. Conclusion: Patients with craniopharyngioma generally present late, and the visual symptoms are often preceded by a long history of systemic symptoms. Children are more likely to present with systemic symptoms than adults. Visual field pleomorphism is a feature of craniopharyngioma and occurred in one-third of the patients. Local recurrence is common. Although magnetic resonance imaging is the recommended means of follow up, regular neuro-ophthalmic review is useful in the early detection of anterior visual pathway compression by recurrent tumour. [source] Identification of risk factors associated with nosocomial infection by rotavirus P4G2, in a neonatal unit of a tertiary-care hospitalCLINICAL MICROBIOLOGY AND INFECTION, Issue 3 2009R. Herruzo Abstract A rotavirus outbreak in newborns admitted to the ,La Paz' University Hospital, Madrid was detected, followed up and controlled. Uninfected children were selected as control subjects. Samples of faeces were taken once or twice weekly from all the newborns, including those who were asymptomatic and who were admitted to the neonatal unit for early detection of rotavirus and the positive were separated from the rest of the neonates. Contact-related precautions were taken for all patients, and alcohol solutions were used for hand washing. During the months of the outbreak, 1773 children were admitted to the hospital, 131 of whom were affected by the rotavirus infection (7.4%). Of these, 72 (55%) had symptomatic infections. In the first month of the outbreak, nine cases of necrotizing enterocolitis were diagnosed (one patient developed massive intestinal necrosis). The infections (symptomatic and asymptomatic) presented a bimodal distribution caused by a new outbreak of rotavirus type P4G2 after two patients who had acquired the infection outside the hospital were admitted when the first outbreak was subsiding. The characteristics of cases and controls were analysed using bivariate and multivariate methods (non-conditional multivariate logistic regression) to identify four risk factors strongly associated with rotavirus infection: premature birth, infections other than rotavirus, malformation, and changes in glycaemia and/or presence of jaundice. [source] Melancholic symptoms as assessed by the Hamilton Depression Rating Scale and outcomes with and without electroconvulsive therapy on an in-patient mood disorders unitACTA NEUROPSYCHIATRICA, Issue 1 2010Keith G. Rasmussen Rasmussen KG, Stevens SR, Kung S, Mohan A. Melancholic symptoms as assessed by the Hamilton Depression Rating Scale and outcomes with and without electroconvulsive therapy on an in-patient mood disorders unit. Background: We investigated whether 24-item Hamilton Rating Scale for Depression (HamD24)-based melancholia ratings correlated with treatment outcome, with special focus on whether electroconvulsive therapy (ECT) was used in depressed patients treated on an in-patient mood disorders unit. Methods: We analysed the data on ECT- versus non-ECT-treated patients' outcomes relative to melancholia subscale scores. Two HamD24 -based melancholia rating scale scores were computed for 201 depressed in-patients at admission and discharge. Baseline melancholia ratings were analysed to see if they correlated with improvement in total HamD24 scores. We also tested to see if the melancholia subscales followed unimodal or bimodal distributions. Results: Melancholic symptoms as assessed by one of the HamD24 -based subscales directly correlated with overall improvement. Although ECT treatment was associated with greater improvement than was noted in non-ECT-treated patients, severity of melancholia ratings did not affect this relationship. Finally, both melancholia subscale scores followed approximately unimodal distributions. Conclusions: HamD24 -based methods to assess severity of melancholic symptoms have limited clinical utility on an in-patient mood disorders unit in general, and for predicting ECT response in particular. Furthermore, these methods do not seem to identify bimodal populations of depressed patients (i.e. melancholic vs. non-melancholic). [source] | ||||||||||||||||||||||