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Rising Temperature (rising + temperature)
Selected AbstractsDeclines in Leaf Litter Nitrogen Linked to Rising Temperatures in a Wet Tropical ForestBIOTROPICA, Issue 5 2010Katherine Tully ABSTRACT In the tropics rainfall can vary by hundreds of millimeters from month to month, while mean temperatures fluctuate by only a few degrees. Nevertheless, during this 7-year study, we observed 35,52 percent declines in litter nitrogen concentrations in response to small increases in minimum temperature, with no response to the larger oscillations in rainfall. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp. [source] Storage and mobility of black carbon in permafrost soils of the forest tundra ecotone in Northern SiberiaGLOBAL CHANGE BIOLOGY, Issue 6 2008GEORG GUGGENBERGER Abstract Boreal permafrost soils store large amounts of organic carbon (OC). Parts of this carbon (C) might be black carbon (BC) generated during vegetation fires. Rising temperature and permafrost degradation is expected to have different consequences for OC and BC, because BC is considered to be a refractory subfraction of soil organic matter. To get some insight into stocks, variability, and characteristics of BC in permafrost soils, we estimated the benzene polycarboxylic acid (BPCA) method-specific composition and storage of BC, i.e. BPCA-BC, in a 0.44 km2 -sized catchment at the forest tundra ecotone in northern Siberia. Furthermore, we assessed the BPCA-BC export with the stream draining the catchment. The catchment is composed of various landscape units with south-southwest (SSW) exposed mineral soils characterized by thick active layer or lacking permafrost, north-northeast (NNE) faced mineral soils with thin active layer, and permafrost-affected raised bogs in plateau positions showing in part thermokarst formation. There were indications of vegetation fires at all landscape units. BC was ubiquitous in the catchment soils and BPCA-BC amounted to 0.6,3.0% of OC. This corresponded to a BC storage of 22,3440 g m,2. The relative contribution of BPCA-BC to OC, as well as the absolute stocks of BPCA-BC were largest in the intact bogs with a shallow active layer followed by mineral soils of the NNE aspects. In both landscape units, a large proportion of BPCA-BC was stored within the permafrost. In contrast, mineral soils with thick active layer or lacking permafrost and organic soils subjected to thermokarst formation stored less BPCA-BC. Permafrost is, hence, not only a crucial factor in the storage of OC but also of BC. In the stream water BPCA-BC amounted on an average to 3.9% of OC, and a yearly export of 0.10 g BPCA-BC m,2 was calculated, most of it occurring during the period of snow melt with dominance of surface flow. This suggests that BC mobility in dissolved and colloidal phase is an important pathway of BC export from the catchment. Such a transport mechanism may explain the high BC concentrations found in sediments of the Arctic Ocean. [source] Continuous changes in the optical properties of liver tissue during laser-induced interstitial thermotherapyLASERS IN SURGERY AND MEDICINE, Issue 4 2001Joerg P. Ritz MD Abstract Background and Objective Laser-induced thermotherapy (LITT) is a promising treatment for irresectable liver tumors. To predict the effects of laser applications and to optimize treatment planning in LITT, it is essential to gain knowledge about light distribution in tissue, tissue optical properties (absorption, scattering, anisotropy, penetration depth), and their continuous changes during therapy. Study Design/Materials and Methods Measurements of optical properties were performed with a double integrating-sphere system and a laser diode (830 nm). Porcine liver tissue samples were examined in a native state (35°C) and after exposure to different temperatures (45°C to 80°C). Results Rising temperature was accompanied by a decrease in the absorption coefficient and anisotropy factor and an increase in the scattering coefficient. These changes were only significant in the temperature range of 50° to 65°C (P,<,0.01). The optical penetration depth decreased from 3.1mm in the native state to 1.7mm at 65°C (P,<,0.01). Above 65°, there was no significant change in the tissue optical properties. Conclusions The optical properties of liver tissue change significantly under the influence of tissue heating, resulting in a decreased optical penetration depth. These changes occur mainly in the temperature range of 50°C to 65°C, corresponding to protein denaturation. To ensure a safe and effective procedure, an adjustment of the laser power to the actual penetration depth is recommended during therapy. Lasers Surg. Lasers Surg. Med. 28:307,312, 2001. © 2001 Wiley-Liss, Inc. [source] Biogeography meets conservation: the genetic structure of the endangered lycaenid butterfly Lycaena helle (Denis & Schiffermüller, 1775)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010JAN CHRISTIAN HABEL Cold-adapted species are thought to have had their largest distribution ranges in central Europe during the glacial periods. Postglacial warming caused severe range shifts of such taxa into higher latitudes and altitudes. We selected the boreomontane butterfly Lycaena helle (Denis & Schiffermüller, 1775) as an example to demonstrate the genetic effects of range changes, and to document the recent status of highly fragmented remnant populations. We analysed five polymorphic microsatellite loci in 1059 individuals sampled at 50 different localities scattered over the European distribution area of the species. Genetic differentiation was strong among the mountain ranges of western Europe, but we did not detect similarly distinct genetic groups following a geographical pattern in the more eastern areas. The Fennoscandian populations form a separate genetic group, and provide evidence for a colonization from southern Finland via northern Scandinavia to south-central Sweden. Species distribution modelling suggests a large extension of the spatial distribution during the last glacial maximum, but highlights strong retractions to a few mountain areas under current conditions. These findings, combined with our genetic data, suggest a more or less continuous distribution of L. helle throughout central Europe at the end of the last ice age. As a consequence of postglacial warming, the species retreated northwards to Fennoscandia and escaped increasing temperatures through altitudinal shifts. Therefore, the species is today restricted to population remnants located at the mountain tops of western Europe, genetically isolated from each other, and evolved into genetically unique entities. Rising temperatures and advancing habitat destruction threaten this wealth of biodiversity. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 155,168. [source] Global pattern of NPP to GPP ratio derived from MODIS data: effects of ecosystem type, geographical location and climateGLOBAL ECOLOGY, Issue 3 2009Yangjian Zhang ABSTRACT Aim, To examine the global pattern of the net primary production (NPP)/gross primary production (GPP) ratio of the Earth's land area along geographical and climatic gradients. Location, The global planetary ecosystem. Methods, The 4-year average annual NPP/GPP ratio of the Earth's land area was calculated using 2000,03 Moderate Resolution Imaging Spectroradiometer (MODIS) data. The global pattern of the NPP/GPP ratio was investigated by comparing it among each typical terrestrial ecosystem and plotting it along a geographical and climatic gradient, including latitude, altitude, temperature and precipitation. Results, The global terrestrial ecosystem had an average NPP/GPP ratio value of 0.52 with minor variation from 2000 to 2003. However, the NPP/GPP ratio showed considerable spatial variation associated with ecosystem type, geographical location and climate. Densely vegetated ecosystems had a lower NPP/GPP ratio than sparsely vegetated ecosystems. Forest ecosystems had a lower NPP/GPP ratio than shrub and herbaceous ecosystems. Geographically, the NPP/GPP ratio increased with altitude. In the Southern Hemisphere, the NPP/GPP ratio decreased along latitude from 30° to 10° and it exhibited high fluctuation in the Northern Hemisphere. Climatically, the NPP/GPP ratio exhibited a decreasing trend along enhanced precipitation when it was less than 2300 mm year,1 and a static trend when the annual precipitation was over 2300 mm. The NPP/GPP ratio showed a decreasing trend along temperature when it was between ,20 °C and 10 °C, and showed an increasing trend along rising temperature when it was between ,10 °C and 20 °C. Within each ecosystem, the NPP/GPP ratio revealed a similar trend to the global trend along temperature and precipitation. Conclusions, The NPP/GPP ratio exhibited a pattern depending on the main climatic characteristics such as temperature and precipitation and geographical factors such as latitude and altitude. The findings of this research challenge the widely held assumption that the NPP/GPP ratio is consistent regardless of ecosystem type. [source] Use of micro-Raman spectroscopy to study reaction kinetics in blended white cement pastes containing metakaolinJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2009Moisés Frías Abstract Curing temperature is known to play an important role in the formation, development, and stability of the hydrated phases appearing during pozzolanic reactions (chemical reaction between puzzolanic addition, metakaolin (MK), and calcium hydroxide from cement hydration). A typical example of this important reaction is to be found in metakaolin-bearing cement pastes, characterized by hexagonal phases whose thermodynamic stability declines with rising temperature. These phases cannot be exhaustively researched with traditional techniques (such as X-ray diffraction) due to their poor crystallinity. Consequently, micro-Raman spectroscopy was used in the present study to explore the behavior of white cement paste blends containing 0, 10, and 25% MK at two curing temperatures (20 and 60 °C). This led to the identification, for the first time using Raman spectroscopy, of phases C2ASH81 (stratlingite) and C3ASH6, which appear in the MK,white cement reaction. The CSH gel formed was characterized by Q1 dimers and a C/S ratio of 1.3,1.5. Raising the curing temperature favored the formation of C4AH13. Copyright © 2009 John Wiley & Sons, Ltd. [source] Local Viscosity of Si-O-C-N Nanoscale Amorphous Phases at Ceramic Grain BoundariesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2001Giuseppe Pezzotti Internal friction characterization has been used to quantitatively assess the viscosity characteristics of Si-O-C-N glasses segregated to nanometer-sized grain boundaries of polycrystalline Si3N4 and SiC ceramics. A relaxation peak of internal friction, which arises with rising temperature from the viscous sliding of glassy grain boundaries, was systematically collected and analyzed with respect to its shift upon changing the oscillation frequency. As a result of such an analysis, both activation energy for viscous grain-boundary flow and inherent viscosity of the intergranular glass film could be quantitatively evaluated. Two main features are shown: (i) the presence of N and/or C greatly affects the viscosity characteristics of SiO2 phases at Si3N4 and SiC grain boundaries; and (ii) the internal friction method has potential as a unique experimental tool for understanding the local properties of nanoscale amorphous phases in new ceramic materials. [source] Model of temperature dependent crystal relaxationPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2006Eva Mihóková Abstract Anomalous decay of the slow emission component in certain doped alkali halides was explained by the creation of a discrete breather in the immediate neighborhood of the impurity. It was experimentally observed that with rising temperature the decay anomaly becomes less pronounced, finally disappearing in the range 100 K to150 K (depending on the substance). In view of the breather explanation, this temperature dependence should be a consequence of the effect of temperature on breathers. We present an improved model of the dissipative effects of temperature on lattice breathers so as to compare it to the observed experimental temperature behavior. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The apparent temperature response of leaf respiration depends on the timescale of measurements: a study of two cold climate speciesPLANT BIOLOGY, Issue 2 2008D. Bruhn Abstract Productivity and climate models often use a constant Q10 for plant respiration, assuming tight control of respiration by temperature. We studied the temperature response of leaf respiration of two cold climate species (the Australian tree Eucalyptus pauciflora and the subantarctic megaherb Pringlea antiscorbutica, both measured in a field setting) on a short timescale (minutes) during different times within a diel course, and on a longer timescale, using diel variations in ambient temperature. There were great variations in Q10 depending on measuring day, measuring time and measuring method. When Q10 was calculated from short-term (15 min) manipulations of leaf temperature, the resulting values were usually markedly smaller than when Q10 was calculated from measurements at ambient leaf temperatures spread over a day. While for E. pauciflora, Q10 estimates decreased with rising temperature (corroborating the concept of a temperature-dependent Q10), the opposite was the case for P. antiscorbutica. Clearly, factors other than temperature co-regulate both leaf respiration rates and temperature sensitivity and contribute to diel and seasonal variation of respiration. [source] Malignant hyperthermia presenting during laparoscopic adrenalectomyANAESTHESIA, Issue 5 2008S. S. O'Neill Summary A 44-year-old man presented for elective laparoscopic adrenalectomy. During the procedure his end-tidal carbon dioxide readings rose steadily. We assumed that this was due to a prolonged carbon dioxide pneumoperitoneum until he developed ST segment depression on his electrocardiogram and a rapid rise in temperature. A diagnosis of malignant hyperthermia was made in view of the rising temperature and carbon dioxide. He responded to cooling and intravenous dantrolene. He was later confirmed to be malignant hyperthermia-susceptible on in vitro contracture testing of a muscle biopsy. The diagnosis was delayed as the early signs of malignant hyperthermia are the same as the expected physiological changes in laparoscopic surgery. As laparoscopic surgery continues to expand we advocate vigilance to ensure early identification of this rare but potentially devastating condition. [source] Thermal photon dispersion law and modified black-body spectraANNALEN DER PHYSIK, Issue 4 2009J. Ludescher Abstract Based on the postulate that photon propagation is governed by an SU(2) gauge principle we numerically compute the one-loop dispersion for thermalized photon propagation on the radiatively induced mass shell. Formerly, the dispersion was addressed by assuming p2 = 0. While this approximation turns out to be excellent for temperatures , 2 TCMB the exact result exhibits a much faster (power-like) shrinking of the gap in the black-body spectral intensity with rising temperature. Our previous statements on anomalous large-angle CMB temperature-temperature correlations, obtained in the approximation p2 = 0, remain valid. [source] Host plant development, water level and water parameters shape Phragmites australis -associated oomycete communities and determine reed pathogen dynamics in a large lakeFEMS MICROBIOLOGY ECOLOGY, Issue 2 2009Anna Wielgoss Abstract In a 3-year-study, we analysed the population dynamics of the reed pathogen Pythium phragmitis and other reed-associated oomycetes colonizing fresh and dried reed leaves in the littoral zone of a large lake. Oomycete communities derived from internal transcribed spacer clone libraries were clearly differentiated according to substrate and seasonal influences. In fresh leaves, diverse communities consisting of P. phragmitis and other reed-associated pathogens were generally dominant. Pythium phragmitis populations peaked in spring with the emergence of young reed shoots, and in autumn after extreme flooding events. In summer it decreased with falling water levels, changing water chemistry and rising temperatures. Another Pythium species was also highly abundant in fresh leaves throughout the year and might represent a new, as-yet uncultured reed pathogen. In dried leaves, reed pathogens were rarely detected, whereas saprophytic species occurred abundantly during all seasons. Saprophyte communities were less diverse, less temperature sensitive and independent of reed development. In general, our results provide evidence for the occurrence of highly specialized sets of reed-associated oomycetes in a natural reed ecosystem. Quantitative analyses (clone abundances and quantitative real-time PCR) revealed that the reed pathogen P. phragmitis is particularly affected by changing water levels, water chemistry and the stage of reed development. [source] | ||||||||||||||||