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Selected AbstractsCaladium bicolor (Araceae) and Cyclocephala celata (Coleoptera, Dynastinae): A Well-Established Pollination System in the Northern Atlantic Rainforest of Pernambuco, BrazilPLANT BIOLOGY, Issue 4 2006A. C. D. Maia Abstract: Flowering, pollination ecology, and floral thermogenesis of Caladium bicolor were studied in the Atlantic Rainforest of Pernambuco, NE Brazil. Inflorescences of this species are adapted to the characteristic pollination syndrome performed by Cyclocephalini beetles. They bear nutritious rewards inside well-developed floral chambers and exhibit a thermogenic cycle which is synchronized to the activity period of visiting beetles. Heating intervals of the spadix were observed during consecutive evenings corresponding to the beginning of the female and male phases of anthesis. Highest temperatures were recorded during the longer-lasting female phase. An intense sweet odour was volatized on both evenings. Beetles of a single species, Cyclocephala celata, were attracted to odoriferous inflorescences of C. bicolor and are reported for the first time as Araceae visitors. All the inflorescences visited by C. celata developed into infructescences, whereas unvisited inflorescences showed no fruit development. Findings of previous studies in the Amazon basin of Surinam indicated that Cyclocephala rustica is a likely pollinator of C. bicolor. This leads to the assumption that locally abundant Cyclocephalini species are involved in the pollination of this species. [source] Factors affecting the formation of misoriented domains in 6H-SiC single crystals grown by PVT methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2009T. H. Peng Abstract Misoriented domains (MDs) are common defects in 6H-SiC single crystals. We performed an experimental study on the formation of MDs in 2-inch 6H-SiC single crystals. Micro-Raman spectroscopy revealed that the polytype of MDs was mainly 4H-SiC. By changing growth conditions, it was found that the MDs' formation was closely related to growth rate and the position of highest temperature relative to growth interface. When the growth rate of ingots was relatively high the MDs were more likely to form. Furthermore, the nearer growth interface the position of highest temperature was, the larger the size of the MDs. Based on our experimental findings we suggested that the MDs' formation and the polytype switching from 6H- to 4H-SiC were due to too large axial and/or radial temperature gradients. The results would be helpful to improve the quality of SiC single crystals grown by PVT technique. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effects of time of seed maturation on dormancy and germination requirements of Sporobolus spicatus (Vahl) Kunth, a native desert grass of the United Arab EmiratesGRASSLAND SCIENCE, Issue 1 2009Ali El-Keblawy Abstract The effect of time of seed maturation on dormancy and germination requirements was determined for seeds of Sporobolus spicatus (Vahl) Kunth, a species that could be used in rehabilitation of the degraded salt-affected habitats. Seeds of S. spicatus were collected in May, August and December 2005 and March 2006 from a population around Al-Ain City, United Arab Emirates (UAE). Seeds were germinated in incubators adjusted at 20°C, 25°C, 30°C and 35°C in continuous light and in darkness. Seeds incubated at the highest temperature (35°C) germinated significantly greater and faster, compared to those at the lower temperatures. The highest germination percentage in S. spicatus was observed for seeds matured during August, followed by those matured in December and May, but the lowest germination was recorded for seeds of March. Seeds of August germinated significantly greater in dark than in light, but the reverse was true for seeds of May. Germination rate was significantly faster for seeds of December than that of other seed lots, even at the lower temperature. The results are discussed in the light of the adaptive significance of the production of tiny seeds at different times of the year in S. spicatus. [source] Removal of gutta-percha from root canals using an Nd:YAG laserINTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2003D. Vidu Abstract Aim, To examine the use of an Nd:YAG laser in removing gutta-percha fillings from root canals when used in conjunction with eucalyptol, dimethylformamide (DMF) or no solvent. Methodology, Root-canal fillings (sealer and gutta-percha) were removed with laser irradiation of 20 Hz/1.5 W from 30 roots randomly divided in three groups. In group 1, the solvent was eucalyptol; in group 2, the solvent was DMF; and in group 3, no solvent was used. Laser irradiation was performed until the temperature measured on the root surface increased by 4 °C over room temperature. The treatment was deemed complete when the apical foramen was reached with the optical fibre and a reamer. The samples were split longitudinally, and the area of remaining gutta-percha on the root-canal walls was determined with the aid of a computer program. The total number of laser pulses to achieve length and the highest temperature recorded was determined for each tooth. The results were statistically analysed using Student's t -test (P < 0.05) for independent samples. Results, The average temperature increase in group 1 was 9.17 ± 0.56 °C; in group 2, 9.56 ± 0.28 °C; and in group 3, 8.29 ± 0.41 °C. The shortest time to achieve length was in group 3 (6.4 ± 0.49 min), then in group 1 (6.7 ± 0.85 min) and group 2 (7.05 ± 0.79 min). The area of remaining gutta-percha was the largest in group 2 (6.13 ± 5.76%), whilst the smallest was for group 3 (4.69 ± 4.03%), but the difference was not statistically significant. The number of pulses was not statistically significant between the groups. Conclusions, Use of an Nd:YAG laser alone is capable of softening gutta-percha. The addition of solvents did not improve the retreatment, either in terms of the time required for the procedure or in terms of the area of remaining gutta-percha on root-canal walls. [source] Non-isothermal multi-phase modeling of PEM fuel cell cathodeINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2010Nada Zamel Abstract In this study, numerical simulation has been carried out for the heat transfer and temperature distribution in the cathode of polymer electrolyte membrane fuel cells along with the multi-phase and multi-species transport under the steady-state condition. The commercial software, COMSOL Multiphysics, is used to solve the conservation equations for momentum, mass, species, charge and energy numerically. The conservation equations are applied to the solid, liquid and vapor phases in the bipolar plate and gas diffusion (GDL) and catalyst layers of a two-dimensional cross section of the cathode. The catalyst layer is assumed to be a finite domain and the water production in the catalyst layer is considered to be in the liquid form. The temperature distribution in the cathode is simulated and then the effects of the relative humidity of the air stream, the permeability of the cathode and the flow channel shoulder to channel width ratio are investigated. It is shown that the highest temperature change, both in the in-plane and across-the-plane directions, occurs in the GDL, while the highest temperature is reached in the catalyst layer. The distribution of temperature in the bipolar plate is shown to be relatively uniform due to the high thermal conductivity of the plate. A decrease in the inlet relative humidity of the air stream results in the decrease of the maximum temperature due to the absorption of heat during the evaporation of liquid water in the GDL and catalyst layer. The non-uniformity of the temperature distribution, especially in the catalyst layer, is observed with the increase of the permeability of the cathode. Similarly, the decrease of the channel shoulder to channel width ratio leads to a non-uniform distribution of temperature especially under the channel areas. Copyright © 2009 John Wiley & Sons, Ltd. [source] Metamorphism and metamorphic K,Ar ages of the Mesozoic accretionary complex in Northland, New ZealandISLAND ARC, Issue 3 2004Yujiro Nishimura Abstract A southwest dipping Mesozoic accretionary complex, which consists of tectonically imbricated turbiditic mudstone and sandstone, hemipelagic siliceous mudstone, and bedded cherts and basaltic rocks of pelagic origin, is exposed in northern North Island, New Zealand. Interpillow limestone is sometimes contained in the basaltic rocks. The grade of subduction-related metamorphism increases from northeast to southwest, indicating an inverted metamorphic gradient dip. Three metamorphic facies are recognized largely on the basis of mineral parageneses in sedimentary and basaltic rocks: zeolite, prehnite-pumpellyite and pumpellyite-actinolite. From the apparent interplanar spacing d002 data for carbonaceous material, which range from 3.642 to 3.564 Å, the highest grade of metamorphism is considered to have attained only the lowermost grade of the pumpellyite-actinolite facies for which the highest temperature may be approximately 300°C. Metamorphic white mica K,Ar ages are reported for magnetic separates and <2 µm hydraulic elutriation separates from 27 pelitic and semipelitic samples. The age data obtained from elutriation separates are approximately 8 m.y. younger, on average, than those from magnetic separates. The age difference is attributed to the possible admixture of nonequilibrated detrital white mica in the magnetic separates, and the age of the elutriation separates is considered to be the age of metamorphism. If the concept, based on fossil evidence, of the subdivision of the Northland accretionary complex into north and south units is accepted, then the peak age of metamorphism in the north unit is likely to be 180,130 Ma; that is, earliest Middle Jurassic to early Early Cretaceous, whereas that in the south unit is 150,130 Ma; that is, late Late Jurassic to early Early Cretaceous. The age cluster for the north unit correlates with that of the Chrystalls Beach,Taieri Mouth section (uncertain terrane), while the age cluster for the south unit is older than that of the Younger Torlesse Subterrane in the Wellington area, and may be comparable with that of the Nelson and Marlborough areas (Caples and Waipapa terranes). [source] Estimating the timing of growth rings in Atlantic cod otoliths using stable oxygen isotopesJOURNAL OF FISH BIOLOGY, Issue 3 2006H. Høie A technique involving micro-scale sampling of otolith carbonate and analyses of stable oxygen isotope composition was used to relate the zone appearance of the otolith to the seasonal temperature cycle. Otolith opacity could then be related to the timing of zone formation. Otoliths from two groups of Atlantic cod Gadus morhua held under known temperature conditions over a period of 4 and 6 years were examined. The otolith translucency followed the same pattern as the estimated temperature (from otolith ,18O values) in the yearly increments three and four, meaning that the translucent zones were deposited at the seasonal highest temperature in late summer and early autumn. The relative light intensities of otolith yearly increments five and six of older fish (deposited in the same years), however, were not significantly correlated to the estimated temperatures since increased otolith translucency also occurred at low temperatures. This might have been caused by stress in connection with gonad development or starvation during the spawning period. The results showed that this method of coupling otolith opacity and stable oxygen isotope composition can be used to estimate the timing of zone formations in otoliths. [source] Reduction of Aflatoxins by Extrusion-Cooking of Rice MealJOURNAL OF FOOD SCIENCE, Issue 7 2006Miren Castells ABSTRACT:, The objective of this work was to determine the reduction of aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1), and G2 (AFG2) as a function of initial moisture content of samples (24%, 27%, and 30%), barrel temperature (140, 170, and 200 °C), and residence time (30 to 70 s) when artificially contaminated rice meal was extrusion-cooked. Extruded and unextruded samples were analyzed by high-performance liquid chromatography (HPLC). Extrusion-cooking was observed to reduce aflatoxin (AF) content, which ranged from 51% to 95% depending on the type of AF and the studied variables. Only in the case of AFG2 was it found that the higher the temperature, the higher the moisture content, and the longer the residence time, the greater the reduction. Moisture content had a significant influence on reducing AFB2, AFG1, and AFG2 whereas it was not a significant factor affecting the levels of AFB1. Regardless of the type of AF, the lowest reductions were achieved at a temperature of 140 °C. Even though theoretically greater losses would be expected at highest temperature, AFB1 and AFB2 were more reduced by 170 °C than by 200 °C while AFG1 reductions were not statistically different when processing at 170 °C and 200 °C. The decrease of AF followed 1st-order kinetics; the fastest treatment in reducing AF was that at 200 °C when samples containing AFG2 were wetted to 24% and when samples containing AFB1, AFB2, and AFG1 were hydrated to 27%. By contrast, the slowest treatments were observed at a barrel temperature of 140 °C. [source] Chiral separation of omeprazole and several related benzimidazoles using supercritical fluid chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2004M. Jesús del Nozal Abstract A study of the enantiomeric separation of omeprazole and several related benzimidazoles, using supercritical fluid chromatography (SFC), on the amylose based column Chiralpak AD is presented in this work. The effect of the organic modifier as well as temperature on the retention and enantioresolution was investigated. Alcohol-type modifiers provided the best results, allowing the enantiomeric separation of all the compounds studied with resolutions that were in most cases higher than 2, and analysis times lower than 10 minutes. An investigation of the temperature effect revealed that the isoelution temperature was below the working temperature range in only two cases, and hence it was better to work at the highest temperature permitted. [source] TEM/STEM Observation of ZrC Coating Layer for Advanced High-Temperature Gas-Cooled Reactor Fuel, Part IIJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2009Jun Aihara The Japan Atomic Energy Agency (JAEA) has started to study and develop zirconium carbide (ZrC)-coated fuel particles for advanced high-temperature gas-cooled reactors. The ZrC coating layer has been fabricated at JAEA by chemical vapor deposition using a pyrolytic reaction of zirconium bromide. The microstructures of the ZrC layers, whose nominal deposition temperatures could be measured and controlled during the deposition process, were characterized by means of TEM and STEM. In the present study, three batches were prepared and compared with each other as well as the previous batches. The crystallographic orientation of ZrC with regard to the growth direction in the ZrC layers deposited at a constant temperature of 1630 K was different from that deposited at varying temperatures in the 1493,1823 K range. A thin layer of turbostratic carbon was observed at the boundary between pyrolytic carbon and ZrC in particles deposited at the highest temperature among those used in this study (the nominal temperature was 1769 K); no such structure was found in a batch deposited at a lower temperature (the nominal temperature was 1632 K). Therefore, precise control of temperature is shown to be critical to the formation of good ZrC coatings. [source] Soft gamma-ray repeater giant flares in the BATSE short gamma-ray burst catalogue: constraints from spectroscopyMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2005Davide Lazzati ABSTRACT The giant flare observed on 2004 December 27 from SGR 1806,20 has revived the idea that a fraction of short (<2 s) gamma-ray bursts (GRBs) are due to giant flares from soft gamma-ray repeaters (SGRs) located in nearby galaxies. One of the distinguishing characteristics of these events is the thermal (blackbody) spectrum with temperatures ranging from ,50 to ,180 keV, with the highest temperature observed for the initial 0.2-s spike of the 2004 December 27 event. We have analysed the spectra of a complete sample of short GRBs with peak fluxes greater than 4 photon s,1 cm,2 detected by BATSE. Of the 115 short GRBs so selected, only 76 had sufficient signal-to-noise ratio to allow the spectral analysis. We find only three short GRBs with a spectrum well fitted by a blackbody, with 60 ,kT, 90 keV, albeit with a considerably longer duration (i.e. ,1 s) and a more complex light curve than the 2004 December 27 event. This implies a stringent limit on the rate of extragalactic SGR giant flares with spectral properties analogous to the December 27 flare. We conclude that up to 4 per cent of the short GRBs could be associated with giant flares (2, confidence). This implies that either the distance to SGR 1806,20 is smaller than 15 kpc or the rate of Galactic giant flares is lower than the estimated 0.033 yr,1. [source] Effects of ultraviolet radiation and temperature on the ultrastructure of zoospores of the brown macroalga Laminaria hyperboreaPLANT BIOLOGY, Issue 3 2008F. S. Steinhoff Abstract The interactive effects of an 8 h exposure to UV radiation and altered temperatures on the ultrastructure and germination of zoospores of the sublittoral brown alga Laminaria hyperborea (Gunn.) Foslie were investigated for the first time. Spores were exposed to four temperatures (2, 7, 12 and 17 °C) and three light regimes (PAR, PAR + UV-A, PAR + UV-A+UV-B). Freshly-released spores of L. hyperborea lack a cell wall and contain a nucleus with fine granular nucleoplasm and a nucleolus, one chloroplast, several mitochondria, dictyosomes and an endoplasmatic reticulum. Further, several kinds of so-called adhesive vesicles, lipid globuli and physodes containing UV-absorbing phlorotannins are embedded in the cytoplasm. No eye-spot is present. Physodes were found but they were rare and small. After an 8 h exposure to UV-B, the nucleoplasm had a mottled structure, chloroplasts contained plastoglobuli, the structure of the mitochondria changed from crista- to sacculus-type and germination was strongly inhibited at all temperatures. UV-A only had an impact on the ultrastructure at the highest temperature tested. The strongest effects were found at 17 °C, where germination was reduced to 35%, 32% and 9% after exposure to PAR, PAR+UV-A and PAR + UV-A + UV-B, respectively. This study indicates that UV-B radiation has strong damaging effects on the physiology and ultrastructure of zoospores of L. hyperborea. The results are important for developing scenarios for the effect of enhanced UV radiation and increasing temperatures caused by global climate changes. [source] Film extrusion of sunflower protein isolatePOLYMER ENGINEERING & SCIENCE, Issue 11 2006Antoine Rouilly Film extrusion of sunflower protein isolate (SFPI) was studied. The influence of die temperature (85,160°C), water and glycerol contents were investigated through appearance, mechanical and thermomechanical properties, and swelling behavior in water of films. It was demonstrated that highest temperature, well above SFPI denaturation temperature in the compound, highest glycerol content (70 parts for 100 parts of SFPI), and medium water content (20 parts for 100 parts of SFPI) gave the most regular and smoothest film (as seen on SEM micrographs). Its ultimate tensile strength, Young's modulus, and strain at break were, respectively, 3.2 MPa, 17.7 MPa, and 73%. Soaked in water, its swelling was about 186% w/w but the film was quiet insoluble. Effect of temperature and plasticizer content were discussed in relation to the kinetic of SFPI denaturation. These first results are very promising for the development of biodegradable protein-based films. POLYM. ENG. SCI. 46:1635,1640, 2006. © 2006 Society of Plastics Engineers. [source] Nonisothermal comprehensive 3D analysis of polymer melt flow in a coat-hanger diePOLYMER ENGINEERING & SCIENCE, Issue 4 2006Tingqi Wu The nonisothermal flow of Carreau fluid in a coat-hanger die is studied. A general three-dimensional finite volume code is developed for the purpose of flow analysis. The isobars, the isotherms, and the velocity distribution are obtained. Simulation results illustrated that the highest temperature occurred by the center of manifold, rather than the die-lip region because of the combined effects of high shear rate and poor heat conduction, which is important for processing those heat-sensitive materials. In the regions where die gap is relatively small, the wall temperature plays a key role in deciding temperature distribution in the melt. The validity of simulation results is verified experimentally. POLYM. ENG. SCI., 46:406,415, 2006. © 2006 Society of Plastics Engineers. [source] Influence of day length, ambient temperature, and seasonality on daily travel distance in the Yunnan snub-nosed monkey at Jinsichang, Yunnan, ChinaAMERICAN JOURNAL OF PRIMATOLOGY, Issue 3 2009Ren Baoping Abstract This article examines the effect of ambient temperature, day length, weather conditions, and seasonality on daily path length (DPL) of a free-ranging group of Yunnan snub-nosed monkeys (Rhinopithecus bieti) using an auto-released GPS collar. Data were collected from December 17, 2003 to October 22, 2004 at Laojunshan in northwestern Yunnan province, China. The average DPL of the monkey group was 909±472,m (n=291), with the shortest distance being 180,m and the longest distance 3,626,m. Ambient temperature and day length were found to affect DPL. Both factors were positively correlated with DPL, which means that the monkey group traveled greater distances on longer and warmer days. At the study site, three distinct seasons were identified, and DPL did not vary significantly across these periods. The time of sunrise was not correlated with DPL. Nevertheless, we sometimes observed the group starting its daily trip later on cloudy days than on sunny days. Furthermore, weather conditions (e.g. rainy, cloudy, and sunny) did not influence the average DPL of the study group. Overall we found that the primary factors affecting DPL in R. bieti were day length and ambient temperature, especially daily highest temperature. Am. J. Primatol. 71:233,241, 2009. © 2008 Wiley-Liss, Inc. [source] The Effects of Supraoptimal Temperatures on Population Growth and Cortical Patterning in Tetrahymena pyriformis and Tetrahymena thermophila: A ComparisonTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 2 2001JOSEPH FRANKEL ABSTRACT. In this investigation, we compare the multiplication rates and morphogenetic responses of the two most studied Tetrahymena species, T. pyriformis and T. thermophila, at supraoptimal temperatures. Although the upper temperature limits differ greatly in the two species, the pattern of growth responses to high temperature is for the most part similar, with some differences in detail. The transient recovery of cell division at the highest temperature that allows cell division, characteristic of T. pyriformis, is observed in a less distinct form in T. thermophila. Moreover, there is a remarkable difference in developmental response, with drastic abnormalities in patterning of oral structures during the transient recovery of cell division in T. pyriformis, and far more limited abnormalities under similar conditions in T. thermophila. The abnormalities result from spatial disorder in the alignment and orientation of basal body pairs within the early oral primordium, followed by failures in the realignment that normally occurs as oral structures (membranelles and undulating membrane) mature. Both the initial spatial disorder and the failures in realignment are far more severe in T. pyriformis than in T. thermophila. [source] High temperature does not alter fatigability in intact mouse skeletal muscle fibresTHE JOURNAL OF PHYSIOLOGY, Issue 19 2009Nicolas Place Intense activation of skeletal muscle results in fatigue development, which involves impaired function of the muscle cells resulting in weaker and slower contractions. Intense muscle activity also results in increased heat production and muscle temperature may rise by up to ,6°C. Hyperthermia is associated with impaired exercise performance in vivo and recent studies have shown contractile dysfunction and premature fatigue development in easily fatigued muscle fibres stimulated at high temperatures and these defects were attributed to oxidative stress. Here we studied whether fatigue-resistant soleus fibres stimulated at increased temperature show premature fatigue development and whether increasing the level of oxidative stress accelerates fatigue development. Intact single fibres or small bundles of soleus fibres were fatigued by 600 ms tetani given at 2 s intervals at 37°C and 43°C, which is the highest temperature the muscle would experience in vivo. Tetanic force in the unfatigued state was not significantly different at the two temperatures. With 100 fatiguing tetani, force decreased by ,15% at both temperatures; the free cytosolic [Ca2+] (assessed with indo-1) showed a similar ,10% decrease at both temperatures. The oxidative stress during fatigue at 43°C was increased by application of 10 ,m hydrogen peroxide or tert-butyl hydroperoxide and this did not cause premature fatigue development. In summary, fatigue-resistant muscle fibres do not display impaired contractility and fatigue resistance at the highest temperature that mammals, including humans, would experience in vivo. Thus, intrinsic defects in fatigue-resistant muscle fibres cannot explain the decreased physical performance at high temperatures. [source] Atomic displacements at and order of all phase transitions in multiferroic YMnO3 and BaTiO3ACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2009S. C. Abrahams Coordinate analysis of the multiple phase transitions in hexagonal YMnO3 leads to the prediction of a previously unknown aristotype phase, with the resulting phase-transition sequence: P63,cm,(e.g.) ,P63cm,P63/mcm,P63/mmc,P6/mmm. Below the Néel temperature TN, 75,K, the structure is antiferromagnetic with the magnetic symmetry not yet determined. Above TN the P63cm phase is ferroelectric with Curie temperature TC, 1105,K. The nonpolar paramagnetic phase stable between TC and ,,1360,K transforms to a second nonpolar paramagnetic phase stable to ,,1600,K, with unit-cell volume one-third that below 1360,K. The predicted aristotype phase at the highest temperature is nonpolar and paramagnetic, with unit-cell volume reduced by a further factor of 2. Coordinate analysis of the three well known phase transitions undergone by tetragonal BaTiO3, with space-group sequence R3m,Amm2 ,P4mm,Pmm, provides a basis for deriving the aristotype phase in YMnO3. Landau theory allows the I , II, III , IV and IV , V phase transitions in YMnO3, and also the I , II phase transition in BaTiO3, to be continuous; all four, however, unambiguously exhibit first-order characteristics. The origin of phase transitions, permitted by theory to be second order, that are first order instead have not yet been thoroughly investigated; several possibilities are briefly considered. [source] Temperature mediates vector transmission efficiency: inoculum supply and plant infection dynamicsANNALS OF APPLIED BIOLOGY, Issue 3 2009M.P. Daugherty Abstract Climate, particularly environmental temperature, frequently plays an important role in disease epidemiology. This study investigated the role of environmental temperature on transmission of the generalist plant pathogen Xylella fastidiosa by its leafhopper vectors. In this system temperature is known to influence both vector performance and feeding rate, yet the implications for pathogen transmission have not been documented. Experiments were conducted over a range of temperatures to document effects on transmission efficiency of the California native Graphocephala atropunctata (blue,green sharpshooter) and the invasive Homalodisca vitripennis (glassy-winged sharpshooter). Inoculation efficiency of H. vitripennis was positively related to temperature. Graphocephala atropunctata mortality and transmission responded non-linearly to temperature, with the highest rates of both at the highest temperature. The experiment also evaluated whether differences in inoculum supply contributed to plant infection level using quantitative PCR. Although total X. fastidiosa population within G. atropunctata was not related to plant infection, the number of infectious vectors was a strong predictor of plant infection level,suggesting that the number of inoculation events is important in the development of systemic infection of X. fastidiosa in grapevines. These results, along with existing evidence from the literature, point to wide-ranging impacts of climate on the epidemiology of X. fastidiosa diseases. [source] Effect of dissolved oxygen and temperature on growth, survival and body composition of juvenile Farfantepenaeus californiensis (Holmes)AQUACULTURE RESEARCH, Issue 2 2000L. Ocampo Survival, growth and proximal body composition of juvenile Farfantepenaeus californiensis (Holmes) were examined at two dissolved oxygen concentrations (mean 5.8 and 2.6 mg L,1) and three temperatures (19 °C, 23 °C and 27 °C) for 50 days. Three replicate experiments were performed with a 12 h light/dark photoperiod. Survival was 68,85% at the lower dissolved oxygen level and 77,82% at the higher level and was not significantly affected by the treatments (P >,0.01). Growth at the lower oxygen concentration was significantly less (P <,0.01) than at the higher concentration, with growth rates of 2, 12 and 24 mg day,1 from the lowest to the highest temperature and 4, 17 and 26 mg day,1 for the three temperatures at the higher dissolved oxygen level. Body lipids were 1.2% wt/wt at the higher temperature and 2.1% wt/wt at the lower temperature, while proteins were 15.1% wt/wt at the higher temperature and 12.5% wt/wt at the lower temperature. These results indicate that low oxygen levels and low temperature significantly depress growth at this particular stage of life. [source] Phototrophs in high iron microbial mats: microstructure of mats in iron-depositing hot springsFEMS MICROBIOLOGY ECOLOGY, Issue 3 2000Beverly K Pierson Abstract Chocolate Pots Hot Springs in Yellowstone National Park are high in ferrous iron, silica and bicarbonate. The springs are contributing to the active development of an iron formation. The microstructure of photosynthetic microbial mats in these springs was studied with conventional optical microscopy, confocal laser scanning microscopy and transmission electron microscopy. The dominant mats at the highest temperatures (48,54°C) were composed of Synechococcus and Chloroflexus or Pseudanabaena and Mastigocladus. At lower temperatures (36,45°C), a narrow Oscillatoria dominated olive green cyanobacterial mats covering most of the iron deposit. Vertically oriented cyanobacterial filaments were abundant in the top 0.5 mm of the mats. Mineral deposits accumulated beneath this surface layer. The filamentous microstructure and gliding motility may contribute to binding the iron minerals. These activities and heavy mineral encrustation of cyanobacteria may contribute to the growth of the iron deposit. Chocolate Pots Hot Springs provide a model for studying the potential role of photosynthetic prokaryotes in the origin of Precambrian iron formations. [source] Mass mortality in Northwestern Mediterranean rocky benthic communities: effects of the 2003 heat waveGLOBAL CHANGE BIOLOGY, Issue 5 2009J. GARRABOU Abstract Late in summer 2003, extensive mass mortality of at least 25 rocky benthic macro-invertebrate species (mainly gorgonians and sponges) was observed in the entire Northwestern (NW) Mediterranean region, affecting several thousand kilometers of coastline. We were able to characterize the mortality event by studying six areas covering the main regions of the NW Mediterranean basin. The degree of impact on each study area was quantified at 49 sites by estimating the proportion of colonies affected in populations of several gorgonian species compared with reference data obtained in years without mortality signs. According to these data, the western areas (Catalan coast and Balearic Islands) were the least affected, while the central areas (Provence coast and Corsica-Sardinia) showed a moderate impact. The northernmost and eastern areas (Gulf of Genoa and Gulf of Naples) displayed the highest impact, with almost 80% of gorgonian colonies affected. The heat wave of 2003 in Europe caused an anomalous warming of seawater, which reached the highest temperatures ever recorded in the studied regions, between 1 and 3 °C above the climatic values (mean and maximum). Because this exceptional warming was observed in the depth ranges most affected by the mortality, it seems likely that the 2003 anomalous temperature played a key role in the observed mortality event. A correlation analysis between temperature conditions and degree of impact seems to support this hypothesis. Under the present climate warming trend, new mass mortality events may occur in the near future, possibly driving a major biodiversity crisis in the Mediterranean Sea. [source] Intracanal temperature rise evaluation during the usage of the System B: replication of intracanal anatomyINTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2005J. C. Villegas Abstract Aim To evaluate and determine intracanal temperature rises at 2 and 4 mm from the working length (WL) necessary to obtain proper replication of intracanal anatomy with gutta-percha (GP) using the System B heat source during vertical condensation. Methodology A split-tooth model was prepared and artificial shallow depressions were cut in the buccal canal wall 2 and 4 mm from the WL. At the same level on the palatal wall holes were drilled to adapt two thermocouples. The canal was filled using GP in a vertical condensation technique by placing the System B plugger at 2 and 4 mm from the WL in groups A and B, respectively. Two control groups in which no GP was used were carried out placing the plugger 2 and 4 mm from the WL (groups A.c and B.c, respectively) and activating the heat source. Recording of temperature rise was carried out during the filling procedure for groups A and B and during activation for control groups A.c and B.c; the highest temperatures were recorded. After each filling was completed, 3 min were allowed for the GP to cool and the model divided to reveal the filling. Images of the GP were taken with a CCD camera to evaluate the presence of replication of artificial round depressions. In control groups, the temperature was recorded for 20 s after a 3 s activation of the heat source. The rise in temperature was compared between the groups individually at each level (2 or 4 mm) and statistically analysed using one-way anova and Fisher PLSD tests at 5% of significance level (P < 0.05). Results Mean temperature rises of 14 ± 3 and 12 ± 2 °C at 2 and 4 mm from the WL, respectively, were observed in group A fillings, and 4 ± 1 and 6 ± 1 °C at 2 and 4 mm, respectively, in group B fillings. Recordings at 2 mm showed significantly (P < 0.05) higher temperature rises with group A.c when compared with groups B and B.c. Replication of intracanal anatomy with GP was always found in group A fillings at both levels but only 4 mm from the WL in group B fillings. Conclusions Positioning the plugger close to WL and a temperature rise of 6 °C were necessary to obtain replication of intracanal anatomy. A mean temperature rise of 4 °C at 2 mm from WL (group B) resulted in no replication of intracanal anatomy. Further studies simulating clinical conditions are necessary. [source] Water temperature fluctuations and territoriality in the intertidal zone: two possible explanations for the elevational distribution of body size in Graus nigraJOURNAL OF FISH BIOLOGY, Issue 2 2002C. E. Hernández On the central coast of Chile, distribution of body size in Graus nigra varied with tidal pool height. With the objective of determining whether environmental temperature is one of the possible causes which explains the observed distribution pattern, two behavioural responses were analysed during an experimental period of increasing water temperature: number of opercular movements (an indirect measure of energy expenditure) and activity levels. The interactions of temperature × time and body size × time had a significant effect on the number of opercular movements. At low temperatures (13,15° C), large fish reached a maximum number of opercular movements, while small fish reached a maximum only at high temperatures (23,25° C). The interaction temperature × time had a significant effect on activity levels of different body sizes. In general, large fish appeared to be less active than small fish, however, at very high temperatures (24,26° C) all individuals increased their activity levels. These data indicate that small fish are acclimatized to live in a wider range of temperatures (13,23° C), and, for fish of all body sizes, the highest temperatures (23,26° C) probably constitute a suboptimal microhabitat. Strong territoriality was observed, with large individuals displacing smaller individuals. These data suggest that temperature is an important factor in explaining why large individuals are not present in high tidal pools (high temperatures), whereas territoriality explains why small individuals are not in low tidal pools (habitat of large individuals). [source] Linking isoprene with plant thermotolerance, antioxidants and monoterpene emissionsPLANT CELL & ENVIRONMENT, Issue 3 2005J. PEÑUELAS ABSTRACT The purpose of the present study was to test the possible plant thermotolerance role of isoprene and to study its relationship with non-enzymatic antioxidants and terpene emissions. The gas exchange, chlorophyll fluorescence, extent of photo- and oxidative stress, leaf damage, mechanisms of photo- and antioxidant protection, and terpene emission were measured in leaves of Quercus ilex seedlings exposed to a ramp of temperatures of 5 °C steps from 25 to 50 °C growing with and without isoprene (10 µL L,1) fumigation. The results showed that isoprene actually conferred thermotolerance (shifted the decrease of net photosynthetic rates from 35 to 45 °C, increased Fv/Fm at 50 °C from 0.38 to 0.65, and decreased the leaf area damaged from 27 to 15%), that it precluded or delayed the enhancement of the antioxidant non-enzymatic defence conferred by , -tocopherol, ascorbic acid or , -carotene consumption in response to increasing temperatures, and that it decreased by approximately 70% the emissions of monoterpenes at the highest temperatures. This suggests that there are inducible mechanisms triggered by the initial stages of thermal damage that up-regulate these antioxidant compounds at high temperatures and that these mechanisms are somehow suppressed in the presence of exogenous isoprene, which seems to already exert an antioxidant-like behaviour. [source] Migration of the proton in the strong O,H,O hydrogen bond in urea,phosphoric acid (1/1)ACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2001Chick C. Wilson The structure of urea,phosphoric acid is reported at a large number of temperatures in the range 150,335,K from neutron diffraction data collected using a novel multiple single-crystal data collection method. The work focuses on the behaviour of the H atom involved in the short strong O,H,O hydrogen bond in this material. The position of this atom is shown to vary significantly, by around 0.035 ,Å, as a function of temperature, becoming effectively centred at the highest temperatures studied. This result, only accessible due to the accurate determination of H-atom parameters by neutron diffraction, has implications for the potential governing the hydrogen bond. [source] | ||||||||||||||||||||||