Sample records for variable temperature response

  1. Tannat grape composition responses to spatial variability of temperature in an Uruguay's coastal wine region (United States)

    Fourment, Mercedes; Ferrer, Milka; González-Neves, Gustavo; Barbeau, Gérard; Bonnardot, Valérie; Quénol, Hervé


    Spatial variability of temperature was studied in relation to the berry basic composition and secondary compounds of the Tannat cultivar at harvest from vineyards located in Canelones and Montevideo, the most important wine region of Uruguay. Monitoring of berries and recording of temperature were performed in 10 commercial vineyards of Tannat situated in the southern coastal wine region of the country for three vintages (2012, 2013, and 2014). Results from a multivariate correlation analysis between berry composition and temperature over the three vintages showed that (1) Tannat responses to spatial variability of temperature were different over the vintages, (2) correlations between secondary metabolites and temperature were higher than those between primary metabolites, and (3) correlation values between berry composition and climate variables increased when ripening occurred under dry conditions (below average rainfall). For a particular studied vintage (2013), temperatures explained 82.5% of the spatial variability of the berry composition. Daily thermal amplitude was found to be the most important spatial mode of variability with lower values recorded at plots nearest to the sea and more exposed to La Plata River. The highest levels in secondary compounds were found in berries issued from plots situated as far as 18.3 km from La Plata River. The increasing knowledge of temperature spatial variability and its impact on grape berry composition contributes to providing possible issues to adapt grapevine to climate change.

  2. Temperature and pH Responsive Microfibers for Controllable and Variable Ibuprofen Delivery

    Directory of Open Access Journals (Sweden)

    Toan Tran


    Full Text Available Electrospun microfibers (MFs composed of pH and temperature responsive polymers can be used for controllable and variable delivery of ibuprofen. First, electrospinning technique was employed to prepare poly(ε-caprolactone (PCL and poly(N-isopropylacrylamide-co-methacrylic acid (pNIPAM-co-MAA MFs containing ibuprofen. It was found that drug release rates from PCL MFs cannot be significantly varied by either temperature (22–40°C or pH values (1.7–7.4. In contrast, the ibuprofen (IP diffusion rates from pNIPAM-co-MAA MFs were very sensitive to changes in both temperature and pH. The IP release from pNIPAM-co-MAA MFs was highly linear and controllable when the temperature was above the lower critical solution temperature (LCST of pNIPAM-co-MAA (33°C and the pH was lower than the pKa of carboxylic acids (pH 2. At room temperature, however, the release rate was dramatically increased by nearly ten times compared to that at higher temperature and lower pH. Such a unique and controllable drug delivery system could be naturally envisioned to find many practical applications in biomedical and pharmaceutical sciences such as programmable transdermal drug delivery.

  3. Extremophiles in Mineral Sulphide Heaps: Some Bacterial Responses to Variable Temperature, Acidity and Solution Composition

    Directory of Open Access Journals (Sweden)

    Helen R. Watling


    Full Text Available In heap bioleaching, acidophilic extremophiles contribute to enhanced metal extraction from mineral sulphides through the oxidation of Fe(II and/or reduced inorganic sulphur compounds (RISC, such as elemental sulphur or mineral sulphides, or the degradation of organic compounds derived from the ore, biota or reagents used during mineral processing. The impacts of variable solution acidity and composition, as well as temperature on the three microbiological functions have been examined for up to four bacterial species found in mineral sulphide heaps. The results indicate that bacteria adapt to sufficiently high metal concentrations (Cu, Ni, Co, Zn, As to allow them to function in mineral sulphide heaps and, by engaging alternative metabolic pathways, to extend the solution pH range over which growth is sustained. Fluctuating temperatures during start up in sulphide heaps pose the greatest threat to efficient bacterial colonisation. The large masses of ores in bioleaching heaps mean that high temperatures arising from sulphide oxidation are hard to control initially, when the sulphide content of the ore is greatest. During that period, mesophilic and moderately thermophilic bacteria are markedly reduced in both numbers and activity.

  4. A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling (United States)

    Galmés, Jeroni; Hermida-Carrera, Carmen; Laanisto, Lauri; Niinemets, Ülo


    The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis–Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kcatc) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species’ climate and photosynthetic mechanism, with differences in ∆Ha for kcatc among C3 plants from cool and warm environments, and in ∆Ha for kcatc and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species’ growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species’ thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to

  5. Variable temperature superconducting microscope (United States)

    Cheng, Bo; Yeh, W. J.


    We have developed and tested a promising type of superconducting quantum interference device (SQUID) microscope, which can be used to detect vortex motion and can operate in magnetic fields over a large temperature range. The system utilizes a single-loop coupling transformer, consisting of a patterned high Tc superconducting thin film. At one end of the transformer, a 20 μm diam detecting loop is placed close to the sample. At the other end, a large loop is coupled to a NbTi coil, which is connected to a low Tc SQUID sensor. Transformers in a variety of sizes have been tested and calibrated. The results show that the system is capable of detecting the motion of a single vortex. We have used the microscope to study the behavior of moving vortices at various positions in a YBa2Cu3O7 thin film bridge.

  6. Variable effects of temperature on insect herbivory

    Directory of Open Access Journals (Sweden)

    Nathan P. Lemoine


    Full Text Available Rising temperatures can influence the top-down control of plant biomass by increasing herbivore metabolic demands. Unfortunately, we know relatively little about the effects of temperature on herbivory rates for most insect herbivores in a given community. Evolutionary history, adaptation to local environments, and dietary factors may lead to variable thermal response curves across different species. Here we characterized the effect of temperature on herbivory rates for 21 herbivore-plant pairs, encompassing 14 herbivore and 12 plant species. We show that overall consumption rates increase with temperature between 20 and 30 °C but do not increase further with increasing temperature. However, there is substantial variation in thermal responses among individual herbivore-plant pairs at the highest temperatures. Over one third of the herbivore-plant pairs showed declining consumption rates at high temperatures, while an approximately equal number showed increasing consumption rates. Such variation existed even within herbivore species, as some species exhibited idiosyncratic thermal response curves on different host plants. Thus, rising temperatures, particularly with respect to climate change, may have highly variable effects on plant-herbivore interactions and, ultimately, top-down control of plant biomass.

  7. Collaborative Research: Process-Resolving Decomposition of the Global Temperature Response to Modes of Low Frequency Variability in a Changing Climate

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Yi [Georgia Inst. of Technology, Atlanta, GA (United States)


    DOE-GTRC-05596 11/24/2104 Collaborative Research: Process-Resolving Decomposition of the Global Temperature Response to Modes of Low Frequency Variability in a Changing Climate PI: Dr. Yi Deng (PI) School of Earth and Atmospheric Sciences Georgia Institute of Technology 404-385-1821, El Niño-Southern Oscillation (ENSO) and Annular Modes (AMs) represent respectively the most important modes of low frequency variability in the tropical and extratropical circulations. The projection of future changes in the ENSO and AM variability, however, remains highly uncertain with the state-of-the-science climate models. This project conducted a process-resolving, quantitative evaluations of the ENSO and AM variability in the modern reanalysis observations and in climate model simulations. The goal is to identify and understand the sources of uncertainty and biases in models’ representation of ENSO and AM variability. Using a feedback analysis method originally formulated by one of the collaborative PIs, we partitioned the 3D atmospheric temperature anomalies and surface temperature anomalies associated with ENSO and AM variability into components linked to 1) radiation-related thermodynamic processes such as cloud and water vapor feedbacks, 2) local dynamical processes including convection and turbulent/diffusive energy transfer and 3) non-local dynamical processes such as the horizontal energy transport in the oceans and atmosphere. In the past 4 years, the research conducted at Georgia Tech under the support of this project has led to 15 peer-reviewed publications and 9 conference/workshop presentations. Two graduate students and one postdoctoral fellow also received research training through participating the project activities. This final technical report summarizes key scientific discoveries we made and provides also a list of all publications and conference presentations resulted from research activities at Georgia Tech. The main findings include

  8. Interactions of CO{sub 2} with temperature and other climate variables: response of vegetation. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Knipling, E.B.


    The overall objectives of this project were: (1) to examine experimentally, for major crop species, the interacting effects of CO{sub 2} concentration, temperature, and water availability on plant growth and development, (2) to model these interactions, and (3) to continue developing physiologically-based mechanistic models for predicting crop response to increased CO{sub 2} concentration and future global climate change. To meet these objectives, controlled-environment studies were conducted on cotton, lemon, rice, and soybean and a long-term open-top chamber study was continued on orange. Much progress was made on development of plant growth models for cotton, wheat, rice, and soybean. In addition, there were two special modeling efforts which have the potential for contributing to all of the crop models. These efforts are concerned with modeling root growth and physical and chemical processes in soil and with modeling the effect of stomatal aperture on photosynthesis and transpiration rates as a function of CO{sub 2} concentration, temperature, and vapor pressure deficit. The root growth and soil process modeling is important because it enables us to estimate the water available to the plant. The modeling of effects of stomatal aperture on photosynthesis and transpiration rates enables them to estimate dry weight gain and water use by the plant. These are both important components of the interaction of CO{sub 2} concentration with temperature and water availability. The work on stomatal aperture, photosynthesis, and transpiration has the added benefit of allowing us to improve predictions of energy partitioning by the terrestrial biosphere. The lack of realistic energy partitioning is a serious deficiency of the present general circulation models which are used to predict how climate will change. An additional important aspect of the rice experiments is a study of methane emissions of paddy-grown (i.e., flooded) rice grown under two levels of CO{sub 2} and three

  9. Measurement of very rapidly variable temperatures

    International Nuclear Information System (INIS)

    Elberg, S.; Mathonnet, P.


    Bibliographical research and visits to laboratories were undertaken in order to survey the different techniques used to measure rapidly variable temperatures, specifying the limits in maximum temperature and variation rate (time constant). On the basis of the bibliographical study these techniques were classified in three categories according to the physical meaning of their response time. Extension of the bibliographical research to methods using fast temperature variation measurement techniques and visits to research and industrial laboratories gave in an idea of the problems raised by the application of these methods. The use of these techniques in fields other than those for which they were developed can sometimes be awkward in the case of thermometric probe devices where the time constant cannot generally be specified [fr

  10. Variable responses of benthic communities to anomalously warm sea temperatures on a high-latitude coral reef. (United States)

    Bridge, Tom C L; Ferrari, Renata; Bryson, Mitch; Hovey, Renae; Figueira, Will F; Williams, Stefan B; Pizarro, Oscar; Harborne, Alastair R; Byrne, Maria


    High-latitude reefs support unique ecological communities occurring at the biogeographic boundaries between tropical and temperate marine ecosystems. Due to their lower ambient temperatures, they are regarded as potential refugia for tropical species shifting poleward due to rising sea temperatures. However, acute warming events can cause rapid shifts in the composition of high-latitude reef communities, including range contractions of temperate macroalgae and bleaching-induced mortality in corals. While bleaching has been reported on numerous high-latitude reefs, post-bleaching trajectories of benthic communities are poorly described. Consequently, the longer-term effects of thermal anomalies on high-latitude reefs are difficult to predict. Here, we use an autonomous underwater vehicle to conduct repeated surveys of three 625 m(2) plots on a coral-dominated high-latitude reef in the Houtman Abrolhos Islands, Western Australia, over a four-year period spanning a large-magnitude thermal anomaly. Quantification of benthic communities revealed high coral cover (>70%, comprising three main morphospecies) prior to the bleaching event. Plating Montipora was most susceptible to bleaching, but in the plot where it was most abundant, coral cover did not change significantly because of post-bleaching increases in branching Acropora. In the other two plots, coral cover decreased while macroalgal cover increased markedly. Overall, coral cover declined from 73% to 59% over the course of the study, while macroalgal cover increased from 11% to 24%. The significant differences in impacts and post-bleaching trajectories among plots underline the importance of understanding the underlying causes of such variation to improve predictions of how climate change will affect reefs, especially at high-latitudes.

  11. Variable responses of benthic communities to anomalously warm sea temperatures on a high-latitude coral reef.

    Directory of Open Access Journals (Sweden)

    Tom C L Bridge

    Full Text Available High-latitude reefs support unique ecological communities occurring at the biogeographic boundaries between tropical and temperate marine ecosystems. Due to their lower ambient temperatures, they are regarded as potential refugia for tropical species shifting poleward due to rising sea temperatures. However, acute warming events can cause rapid shifts in the composition of high-latitude reef communities, including range contractions of temperate macroalgae and bleaching-induced mortality in corals. While bleaching has been reported on numerous high-latitude reefs, post-bleaching trajectories of benthic communities are poorly described. Consequently, the longer-term effects of thermal anomalies on high-latitude reefs are difficult to predict. Here, we use an autonomous underwater vehicle to conduct repeated surveys of three 625 m(2 plots on a coral-dominated high-latitude reef in the Houtman Abrolhos Islands, Western Australia, over a four-year period spanning a large-magnitude thermal anomaly. Quantification of benthic communities revealed high coral cover (>70%, comprising three main morphospecies prior to the bleaching event. Plating Montipora was most susceptible to bleaching, but in the plot where it was most abundant, coral cover did not change significantly because of post-bleaching increases in branching Acropora. In the other two plots, coral cover decreased while macroalgal cover increased markedly. Overall, coral cover declined from 73% to 59% over the course of the study, while macroalgal cover increased from 11% to 24%. The significant differences in impacts and post-bleaching trajectories among plots underline the importance of understanding the underlying causes of such variation to improve predictions of how climate change will affect reefs, especially at high-latitudes.

  12. Temperature variability over the tropical middle atmosphere

    Directory of Open Access Journals (Sweden)

    K. Mohanakumar


    Full Text Available A study on the variability of temperature in the tropical middle atmosphere over Thumba (8 32' N, 76 52' E, located at the southern part of India, has been carried out based on rocket observations for a period of 20 years, extending from 1970 to 1990. The rocketsonde-derived mean temperatures over Thumba are corrected prior to 1978 and then compared with the middle atmospheric reference model developed from satellite observations and Solar Mesosphere Explorer (SME satellite data. Temperature variability at every 1 km interval in the 25-75 km region was analysed. The tropical stratosphere is found to be highly stable, whereas considerable variability is noted in the middle mesosphere. The effect of seasonal cycle is least in the lower stratosphere. Annual and semi-annual oscillations in temperature are the primary oscillations in the tropical middle atmosphere. Annual temperature oscillations are dominant in the mesosphere and semi-annual oscillations are strong in the stratosphere. The stratopause region is noted to be the part of the middle atmosphere least sensitive to the changes in solar activity and long-term variability.

  13. Temperature responsive track membranes

    International Nuclear Information System (INIS)

    Omichi, H.; Yoshido, M.; Asano, M.; Tamada, H.


    A new track membrane was synthesized by introducing polymeric hydrogel to films. Such a monomer as amino acid group containing acryloyl or methacryloyl was either co-polymerized with diethylene glycol-bis-ally carbonate followed by on beam irradiation and chemical etching, or graft co-polymerized onto a particle track membrane of CR-39. The pore size was controlled in water by changing the water temperature. Some films other than CR-39 were also examined. (author). 11 refs, 7 figs

  14. Bedform response to flow variability (United States)

    Nelson, J.M.; Logan, B.L.; Kinzel, P.J.; Shimizu, Y.; Giri, S.; Shreve, R.L.; McLean, S.R.


    Laboratory observations and computational results for the response of bedform fields to rapid variations in discharge are compared and discussed. The simple case considered here begins with a relatively low discharge over a flat bed on which bedforms are initiated, followed by a short high-flow period with double the original discharge, during which the morphology of the bedforms adjusts, followed in turn by a relatively long period of the original low discharge. For the grain size and hydraulic conditions selected, the Froude number remains subcritical during the experiment, and sediment moves predominantly as bedload. Observations show rapid development of quasi-two-dimensional bedforms during the initial period of low flow with increasing wavelength and height over the initial low-flow period. When the flow increases, the bedforms rapidly increase in wavelength and height, as expected from other empirical results. When the flow decreases back to the original discharge, the height of the bedforms quickly decreases in response, but the wavelength decreases much more slowly. Computational results using an unsteady two-dimensional flow model coupled to a disequilibrium bedload transport model for the same conditions simulate the formation and initial growth of the bedforms fairly accurately and also predict an increase in dimensions during the high-flow period. However, the computational model predicts a much slower rate of wavelength increase, and also performs less accurately during the final low-flow period, where the wavelength remains essentially constant, rather than decreasing. In addition, the numerical results show less variability in bedform wavelength and height than the measured values; the bedform shape is also somewhat different. Based on observations, these discrepancies may result from the simplified model for sediment particle step lengths used in the computational approach. Experiments show that the particle step length varies spatially and

  15. Effects of short-term variability of meteorological variables on soil temperature in permafrost regions (United States)

    Beer, Christian; Porada, Philipp; Ekici, Altug; Brakebusch, Matthias


    Effects of the short-term temporal variability of meteorological variables on soil temperature in northern high-latitude regions have been investigated. For this, a process-oriented land surface model has been driven using an artificially manipulated climate dataset. Short-term climate variability mainly impacts snow depth, and the thermal diffusivity of lichens and bryophytes. These impacts of climate variability on insulating surface layers together substantially alter the heat exchange between atmosphere and soil. As a result, soil temperature is 0.1 to 0.8 °C higher when climate variability is reduced. Earth system models project warming of the Arctic region but also increasing variability of meteorological variables and more often extreme meteorological events. Therefore, our results show that projected future increases in permafrost temperature and active-layer thickness in response to climate change will be lower (i) when taking into account future changes in short-term variability of meteorological variables and (ii) when representing dynamic snow and lichen and bryophyte functions in land surface models.

  16. Borehole temperature variability at Hoher Sonnblick, Austria (United States)

    Heinrich, Georg; Schöner, Wolfgang; Prinz, Rainer; Pfeiler, Stefan; Reisenhofer, Stefan; Riedl, Claudia


    The overarching aim of the project 'Atmosphere - permafrost relationship in the Austrian Alps - atmospheric extreme events and their relevance for the mean state of the active layer (ATMOperm)' is to improve the understanding of the impacts of atmospheric extreme events on the thermal state of the active layer using a combined measurement and modeling approach as the basis for a long-term monitoring strategy. For this purpose, the Sonnblick Observatory at the summit of Hoher Sonnblick (3106 m.a.s.l) is particularly well-suited due to its comprehensive long-term atmospheric and permafrost monitoring network (i.a. three 20 m deep boreholes since 2007). In ATMOperm, a robust and accurate permanent monitoring of active layer thickness at Hoher Sonnblick will be set up using innovative monitoring approaches by automated electrical resistivity tomography (ERT). The ERT monitoring is further supplemented by additional geophysical measurements such as ground penetrating radar, refraction seismic, electromagnetic induction and transient electromagnetics in order to optimally complement the gained ERT information. On the other hand, atmospheric energy fluxes over permafrost ground and their impact on the thermal state of permafrost and active layer thickness with a particular focus on atmospheric extreme events will be investigated based on physically-based permafrost modeling. For model evaluation, the borehole temperature records will play a key role and, therefore, an in-depth quality control of the borehole temperatures is an important prerequisite. In this study we will show preliminary results regarding the borehole temperature variability at Hoher Sonnblick with focus on the active layer. The borehole temperatures will be related to specific atmospheric conditions using the rich data set of atmospheric measurements of the site in order to detect potential errors in the borehole temperature measurements. Furthermore, we will evaluate the potential of filling gaps in

  17. Interactions of CO{sub 2} with temperature and other climate variables: Response of vegetation. Final report, September 1, 1988--August 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Acock, B.; Kimball, B.A.


    The current project was initiated in 1991, and full details of the scope of the project are contained in the original proposal. that original proposal was reviewed and approved for three years funding. Progress made in 1991-92 and 1992-93 was described in annual Progress Reports and Statements of Work. This document summarizes progress made over the duration of the project, but with an emphasis on the final year`s (1993-94) results. Several of the important experiments are ongoing, to the extent that alternative funding could be arranged, and analyses of data from several of the earlier completed experiments is continuing. Therefore, this Final Report is also intermediary in nature, and additional results from this project will be reported in the open literature in the future. The overall objectives of the project were: (1) to examine experimentally, for major crop species, the interacting effects of CO{sub 2} concentration, temperature, and water availability on plant growth and development, (2) to model these interactions, and (3) to continue developing physiologically-based mechanistic models for predicting crop response to increased CO{sub 2} concentration and future global climate change.

  18. Multi-Wheat-Model Ensemble Responses to Interannual Climate Variability (United States)

    Ruane, Alex C.; Hudson, Nicholas I.; Asseng, Senthold; Camarrano, Davide; Ewert, Frank; Martre, Pierre; Boote, Kenneth J.; Thorburn, Peter J.; Aggarwal, Pramod K.; Angulo, Carlos


    We compare 27 wheat models' yield responses to interannual climate variability, analyzed at locations in Argentina, Australia, India, and The Netherlands as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Pilot. Each model simulated 1981e2010 grain yield, and we evaluate results against the interannual variability of growing season temperature, precipitation, and solar radiation. The amount of information used for calibration has only a minor effect on most models' climate response, and even small multi-model ensembles prove beneficial. Wheat model clusters reveal common characteristics of yield response to climate; however models rarely share the same cluster at all four sites indicating substantial independence. Only a weak relationship (R2 0.24) was found between the models' sensitivities to interannual temperature variability and their response to long-termwarming, suggesting that additional processes differentiate climate change impacts from observed climate variability analogs and motivating continuing analysis and model development efforts.

  19. Acoustic response variability in automotive vehicles (United States)

    Hills, E.; Mace, B. R.; Ferguson, N. S.


    A statistical analysis of a series of measurements of the audio-frequency response of a large set of automotive vehicles is presented: a small hatchback model with both a three-door (411 vehicles) and five-door (403 vehicles) derivative and a mid-sized family five-door car (316 vehicles). The sets included vehicles of various specifications, engines, gearboxes, interior trim, wheels and tyres. The tests were performed in a hemianechoic chamber with the temperature and humidity recorded. Two tests were performed on each vehicle and the interior cabin noise measured. In the first, the excitation was acoustically induced by sets of external loudspeakers. In the second test, predominantly structure-borne noise was induced by running the vehicle at a steady speed on a rough roller. For both types of excitation, it is seen that the effects of temperature are small, indicating that manufacturing variability is larger than that due to temperature for the tests conducted. It is also observed that there are no significant outlying vehicles, i.e. there are at most only a few vehicles that consistently have the lowest or highest noise levels over the whole spectrum. For the acoustically excited tests, measured 1/3-octave noise reduction levels typically have a spread of 5 dB or so and the normalised standard deviation of the linear data is typically 0.1 or higher. Regarding the statistical distribution of the linear data, a lognormal distribution is a somewhat better fit than a Gaussian distribution for lower 1/3-octave bands, while the reverse is true at higher frequencies. For the distribution of the overall linear levels, a Gaussian distribution is generally the most representative. As a simple description of the response variability, it is sufficient for this series of measurements to assume that the acoustically induced airborne cabin noise is best described by a Gaussian distribution with a normalised standard deviation between 0.09 and 0.145. There is generally

  20. Identify the dominant variables to predict stream water temperature (United States)

    Chien, H.; Flagler, J.


    Stream water temperature is a critical variable controlling water quality and the health of aquatic ecosystems. Accurate prediction of water temperature and the assessment of the impacts of environmental variables on water temperature variation are critical for water resources management, particularly in the context of water quality and aquatic ecosystem sustainability. The objective of this study is to measure stream water temperature and air temperature and to examine the importance of streamflow on stream water temperature prediction. The measured stream water temperature and air temperature will be used to test two hypotheses: 1) streamflow is a relatively more important factor than air temperature in regulating water temperature, and 2) by combining air temperature and streamflow data stream water temperature can be more accurately estimated. Water and air temperature data loggers are placed at two USGS stream gauge stations #01362357and #01362370, located in the upper Esopus Creek watershed in Phonecia, NY. The ARIMA (autoregressive integrated moving average) time series model is used to analyze the measured water temperature data, identify the dominant environmental variables, and predict the water temperature with identified dominant variable. The preliminary results show that streamflow is not a significant variable in predicting stream water temperature at both USGS gauge stations. Daily mean air temperature is sufficient to predict stream water temperature at this site scale.

  1. Impact of Subsurface Temperature Variability on Meteorological Variability: An AGCM Study (United States)

    Mahanama, S. P.; Koster, R. D.; Liu, P.


    Anomalous atmospheric conditions can lead to surface temperature anomalies, which in turn can lead to temperature anomalies deep in the soil. The deep soil temperature (and the associated ground heat content) has significant memory -- the dissipation of a temperature anomaly may take weeks to months -- and thus deep soil temperature may contribute to the low frequency variability of energy and water variables elsewhere in the system. The memory may even provide some skill to subseasonal and seasonal forecasts. This study uses two long-term AGCM experiments to isolate the contribution of deep soil temperature variability to variability elsewhere in the climate system. The first experiment consists of a standard ensemble of AMIP-type simulations, simulations in which the deep soil temperature variable is allowed to interact with the rest of the system. In the second experiment, the coupling of the deep soil temperature to the rest of the climate system is disabled -- at each grid cell, the local climatological seasonal cycle of deep soil temperature (as determined from the first experiment) is prescribed. By comparing the variability of various atmospheric quantities as generated in the two experiments, we isolate the contribution of interactive deep soil temperature to that variability. The results show that interactive deep soil temperature contributes significantly to surface temperature variability. Interactive deep soil temperature, however, reduces the variability of the hydrological cycle (evaporation and precipitation), largely because it allows for a negative feedback between evaporation and temperature.

  2. Multi-wheat-model ensemble responses to interannual climatic variability

    DEFF Research Database (Denmark)

    Ruane, A C; Hudson, N I; Asseng, S


    We compare 27 wheat models' yield responses to interannual climate variability, analyzed at locations in Argentina, Australia, India, and The Netherlands as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Pilot. Each model simulated 1981–2010 grain yield, and ......-term warming, suggesting that additional processes differentiate climate change impacts from observed climate variability analogs and motivating continuing analysis and model development efforts.......We compare 27 wheat models' yield responses to interannual climate variability, analyzed at locations in Argentina, Australia, India, and The Netherlands as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Pilot. Each model simulated 1981–2010 grain yield, and we...... evaluate results against the interannual variability of growing season temperature, precipitation, and solar radiation. The amount of information used for calibration has only a minor effect on most models' climate response, and even small multi-model ensembles prove beneficial. Wheat model clusters reveal...

  3. The land/ocean temperature contrast in natural variability


    Tyrrell, Nicholas Luke


    In global warming scenarios, global land surface temperatures (T_land) warm with greater amplitude than sea surface temperatures (SSTs), leading to a land/ocean warming temperature contrast. This land/ocean contrast is not only due to the different heat capacities of the land and ocean as it exists for transient and equilibrium scenarios. Similarly, the interannual variability of T_land is larger than the covariant interannual SST variability, leading to a land/ocean ...

  4. Variable Temperature Equipment for a Commercial Magnetic Susceptibility Balance (United States)

    Lotz, Albert


    Variable temperature equipment for the magnetic susceptibility balance MSB-MK1 of Sherwood Scientific, Ltd., is described. The sample temperature is controlled with streaming air heated by water in a heat exchanger. Whereas the balance as sold commercially can be used only for room temperature measurements, the setup we designed extends the…

  5. Native temperature regime influences soil response to simulated warming (United States)

    Timothy G. Whitby; Michael D. Madritch


    Anthropogenic climate change is expected to increase global temperatures and potentially increase soil carbon (C) mineralization, which could lead to a positive feedback between global warming and soil respiration. However the magnitude and spatial variability of belowground responses to warming are not yet fully understood. Some of the variability may depend...

  6. Contribution of solar radiation to decadal temperature variability over land. (United States)

    Wang, Kaicun; Dickinson, Robert E


    Global air temperature has become the primary metric for judging global climate change. The variability of global temperature on a decadal timescale is still poorly understood. This paper examines further one suggested hypothesis, that variations in solar radiation reaching the surface (Rs) have caused much of the observed decadal temperature variability. Because Rs only heats air during the day, its variability is plausibly related to the variability of diurnal temperature range (daily maximum temperature minus its minimum). We show that the variability of diurnal temperature range is consistent with the variability of Rs at timescales from monthly to decadal. This paper uses long comprehensive datasets for diurnal temperature range to establish what has been the contribution of Rs to decadal temperature variability. It shows that Rs over land globally peaked in the 1930s, substantially decreased from the 1940s to the 1970s, and changed little after that. Reduction of Rs caused a reduction of more than 0.2 °C in mean temperature during May to October from the 1940s through the 1970s, and a reduction of nearly 0.2 °C in mean air temperature during November to April from the 1960s through the 1970s. This cooling accounts in part for the near-constant temperature from the 1930s into the 1970s. Since then, neither the rapid increase in temperature from the 1970s through the 1990s nor the slowdown of warming in the early twenty-first century appear to be significantly related to changes of Rs.

  7. Forcing, feedback and internal variability in global temperature trends. (United States)

    Marotzke, Jochem; Forster, Piers M


    Most present-generation climate models simulate an increase in global-mean surface temperature (GMST) since 1998, whereas observations suggest a warming hiatus. It is unclear to what extent this mismatch is caused by incorrect model forcing, by incorrect model response to forcing or by random factors. Here we analyse simulations and observations of GMST from 1900 to 2012, and show that the distribution of simulated 15-year trends shows no systematic bias against the observations. Using a multiple regression approach that is physically motivated by surface energy balance, we isolate the impact of radiative forcing, climate feedback and ocean heat uptake on GMST--with the regression residual interpreted as internal variability--and assess all possible 15- and 62-year trends. The differences between simulated and observed trends are dominated by random internal variability over the shorter timescale and by variations in the radiative forcings used to drive models over the longer timescale. For either trend length, spread in simulated climate feedback leaves no traceable imprint on GMST trends or, consequently, on the difference between simulations and observations. The claim that climate models systematically overestimate the response to radiative forcing from increasing greenhouse gas concentrations therefore seems to be unfounded.

  8. [Effects of variable temperature on organic carbon mineralization in typical limestone soils]. (United States)

    Wang, Lian-Ge; Gao, Yan-Hong; Ding, Chang-Huan; Ci, En; Xie, De-Ti


    Soil sampling in the field and incubation experiment in the laboratory were conducted to investigate the responses of soil organic carbon (SOC) mineralization to variable temperature regimes in the topsoil of limestone soils from forest land and dry land. Two incubated limestone soils were sampled from the 0-10 cm layers of typical forest land and dry land respectively, which were distributed in Tianlong Mountain area of Puding county, Guizhou province. The soils were incubated for 56 d under two different temperature regimes including variable temperature (range: 15-25 degrees C, interval: 12 h) and constant temperature (20 degrees C), and the cumulative temperature was the same in the two temperature treatments. In the entire incubation period (56 d), the SOC cumulative mineralization (63.32 mg x kg(-1)) in the limestone soil from dry land (SH) under the variable temperature was lower than that (63.96 mg x kg(-1)) at constant 20 degrees C, and there was no significant difference in the SOC cumulative mineralization between the variable and constant temperature treatments (P variable temperature was significantly lower than that (209.52 mg x kg(-1)) at constant 20 degrees C. The results indicated that the responses of SOC mineralization to the variable temperature were obviously different between SL and SH soils. The SOC content and composition were significantly different between SL and SH soils affected by vegetation and land use type, which suggested that SOC content and composition were important factors causing the different responses of SOC mineralization to variable temperature between SL and SH soils. In addition, the dissolved organic carbon (DOC) content of two limestone soils were highly (P variable temperature mainly influenced SOC mineralization by changing microbial community activity rather than by changing microbial quantity.

  9. Centile estimation for a proportion response variable. (United States)

    Hossain, Abu; Rigby, Robert; Stasinopoulos, Mikis; Enea, Marco


    This paper introduces two general models for computing centiles when the response variable Y can take values between 0 and 1, inclusive of 0 or 1. The models developed are more flexible alternatives to the beta inflated distribution. The first proposed model employs a flexible four parameter logit skew Student t (logitSST) distribution to model the response variable Y on the unit interval (0, 1), excluding 0 and 1. This model is then extended to the inflated logitSST distribution for Y on the unit interval, including 1. The second model developed in this paper is a generalised Tobit model for Y on the unit interval, including 1. Applying these two models to (1-Y) rather than Y enables modelling of Y on the unit interval including 0 rather than 1. An application of the new models to real data shows that they can provide superior fits. Copyright © 2015 John Wiley & Sons, Ltd.

  10. Internally generated natural variability of global-mean temperatures

    International Nuclear Information System (INIS)

    Wigley, T.M.L.; Raper, S.C.B.


    Quantitative frequency-domain and time-domain estimates are made of an important aspect of natural variability of global-mean temperatures, namely, passive internal variability resulting from the modulation of atmospheric variability by the ocean. The results are derived using an upwelling-diffusion, energy-balance climate model. In the frequency domain, analytical spectral results show a transition from a high-frequency region in which the response is determined by the mixed-layer heat capacity and is independent of the climate sensitivity (time scales less than around 10 years), to a low-frequency region in which the response depends only on the climate sensitivity. In the former region the spectral power is proportional to f -2 , where f is the frequency, while in the latter the power is independent of frequency. The range of validity of these results depends on the components of the climate system that are included in the model. In this case these restrict the low-frequency results to time scales less than about 1,000 years. A qualitative extrapolation is presented in an attempt to explain the observed low-frequency power spectra from deep-sea-core δ 18 O time series. The spectral results are also used to estimate the effective heat capacity of the ocean as a function of frequency. At low frequencies, this can range up to 50 times greater than the heat capacity of the mixed layer. Results in the time domain are obtained by solving the model equations numerically

  11. Air temperature variability in a high-elevation Himalayan catchment

    NARCIS (Netherlands)

    Heynen, Martin; Miles, Evan; Ragettli, Silvan; Buri, Pascal; Immerzeel, Walter W.; Pellicciotti, Francesca


    Air temperature is a key control of processes affecting snow and glaciers in high-elevation catchments, including melt, snowfall and sublimation. It is therefore a key input variable to models of land-surface-atmosphere interaction. Despite this importance, its spatial variability is poorly

  12. Temporal and spatial variability in North Carolina piedmont stream temperature (United States)

    J.L. Boggs; G. Sun; S.G. McNulty; W. Swartley; Treasure E.; W. Summer


    Understanding temporal and spatial patterns of in-stream temperature can provide useful information to managing future impacts of climate change on these systems. This study will compare temporal patterns and spatial variability of headwater in-stream temperature in six catchments in the piedmont of North Carolina in two different geological regions, Carolina slate...

  13. The Southern Oscillation and northern hemisphere temperature variability

    International Nuclear Information System (INIS)

    Ropelewski, C.F.; Halpert, M.S.


    The Southern Oscillation (SO) is the best defined and understood mode of interannual climate variability. The extreme phases of the SO have been identified with global-scale variations in the atmosphere/ocean circulation system and with the modulation of monsoon precipitation on the global scale. While SO-related precipitation has been the subject of several studies, the magnitude of the SO-related temperature variability on the global scale has not been well documented. In this paper the authors provide an estimate of the SO-related temperature variability in the context of monitoring global warming related to the increase in greenhouse gases. This analysis suggested that traditional time series of hemispheric and global temperature anomalies for the calendar year may confuse interannual temperature variability associated with the SO and perceived climate trend. Analyses based on calendar-year data are likely to split the effects of the SO-related temperature variability over two years. The Northern Hemisphere cold season (october through March) time series may be more appropriate to separate the SO-related effects on the hemispheric temperature from other modes of variability. mean interannual temperature anomaly differences associated with the extremes of the So are estimated to be 0.2 C for the October-to-March season in the Northern Hemisphere. In areas directly linked to the SO, the mean interannual differences amount to over 0.5 C. The So cannot account for all the variability in the hemispheric times series of surface temperature estimates, but the SO signal must be properly accounted for if these time series are to be understood

  14. Spatial variability of correlated color temperature of lightning channels

    Directory of Open Access Journals (Sweden)

    Nobuaki Shimoji

    Full Text Available In this paper, we present the spatial variability of the correlated color temperature of lightning channel shown in a digital still image. In order to analyze the correlated color temperature, we calculated chromaticity coordinates of the lightning channels in the digital still image. From results, the spatial variation of the correlated color temperature of the lightning channel was confirmed. Moreover, the results suggest that the correlated color temperature and peak current of the lightning channels are related to each other. Keywords: Lightning, Color analysis, Correlated color temperature, Chromaticity coordinate, CIE 1931 xy-chromaticity diagram

  15. Trends and Variability in Temperature Sensitivity of Lilac Flowering Phenology (United States)

    Wang, Huanjiong; Dai, Junhu; Rutishauser, This; Gonsamo, Alemu; Wu, Chaoyang; Ge, Quansheng


    The responses of plant phenology to temperature variability have many consequences for ecological processes, agriculture, forestry, and human health. Temperature sensitivity (ST) of phenology could measure how and to what degree plant could phenologically track climate change. The long-term trends and spatial patterns in ST have been well studied for vegetative phenology such as leaf unfolding, but trends to be expected for reproductive phenology in the future remain unknown. Here we investigate trends and factors driving the temporal variation of ST of first bloom date (FBD). Using the long-term FBD records during 1963-2013 for common lilac (Syringa vulgaris) from 613 stations in Europe, we compared changes in ST from the beginning to the end of the study period. The Spearman partial correlations were used to assess the importance of four influencing factors. The results showed that the temporal changes in ST of FBD varied considerably among time scales. Mean ST decreased significantly by 0.92 days °C-1 from 1963-1972 to 2004-2013 (P plant species in other climates and environments using similar methods to our study.

  16. Variable intertidal temperature explains why disease endangers black abalone (United States)

    Ben-Horin, Tal; Lenihan, Hunter S.; Lafferty, Kevin D.


    Epidemiological theory suggests that pathogens will not cause host extinctions because agents of disease should fade out when the host population is driven below a threshold density. Nevertheless, infectious diseases have threatened species with extinction on local scales by maintaining high incidence and the ability to spread efficiently even as host populations decline. Intertidal black abalone (Haliotis cracherodii), but not other abalone species, went extinct locally throughout much of southern California following the emergence of a Rickettsiales-like pathogen in the mid-1980s. The rickettsial disease, a condition known as withering syndrome (WS), and associated mortality occur at elevated water temperatures. We measured abalone body temperatures in the field and experimentally manipulated intertidal environmental conditions in the laboratory, testing the influence of mean temperature and daily temperature variability on key epizootiological processes of WS. Daily temperature variability increased the susceptibility of black abalone to infection, but disease expression occurred only at warm water temperatures and was independent of temperature variability. These results imply that high thermal variation of the marine intertidal zone allows the pathogen to readily infect black abalone, but infected individuals remain asymptomatic until water temperatures periodically exceed thresholds modulating WS. Mass mortalities can therefore occur before pathogen transmission is limited by density-dependent factors.

  17. Creep rupture of structures subjected to variable loading and temperature

    International Nuclear Information System (INIS)

    Wojewodzki, W.


    The aim of the present paper is to show on the basis of equations and the analysis of creep mechanisms the possibilities of a description of the creep behavior of material under variable temperature and loading conditions. Also the influence of cyclic proportional loading and temperature gradient upon the rupture life and strains of a thick cylinder is investigated in detail. The obtained theoretical creep curves coincide with the experimental results for investigated steel in the temperature range from 500 0 C to 575 0 C. The constitutive equations together with the functions determined previously are applied to solve the problem of thick cylinder subjected to cyclic proportional pressure and temperature gradient. Numerical results for the thick steel cylinder are presented both in diagrammatical and tabular form. The obtained new results clearly show the significant influence of temperature gradient, cyclic temperature gradient, and cyclic pressure upon the stress redistribution, the magnitude of deformation, the propagation of the front damage and the rupture life. It was found that small temperature fluctuations at elevated temperature can shorten the rupture life very considerably. The introduced description of the creep rupture behavior of material under variable temperature and loading conditions together with the results for the thick cylinder indicate the possibilities of solutions of practical problems encountered in structural mechanics of reactor technology

  18. Method of nuclear reactor control using a variable temperature load dependent set point

    International Nuclear Information System (INIS)

    Kelly, J.J.; Rambo, G.E.


    A method and apparatus for controlling a nuclear reactor in response to a variable average reactor coolant temperature set point is disclosed. The set point is dependent upon percent of full power load demand. A manually-actuated ''droop mode'' of control is provided whereby the reactor coolant temperature is allowed to drop below the set point temperature a predetermined amount wherein the control is switched from reactor control rods exclusively to feedwater flow

  19. Response Variability in Commercial MOSFET SEE Qualification

    International Nuclear Information System (INIS)

    George, J. S.; Clymer, D. A.; Turflinger, T. L.; Mason, L. W.; Stone, S.


    Single-event effects (SEE) evaluation of five different part types of next generation, commercial trench MOSFETs indicates large part-to-part variation in determining a safe operating area (SOA) for drain-source voltage (V_D_S) following a test campaign that exposed >50 samples per part type to heavy ions. These results suggest a determination of a SOA using small sample sizes may fail to capture the full extent of the part-to-part variability. An example method is discussed for establishing a Safe Operating Area using a one-sided statistical tolerance limit based on the number of test samples. Finally, burn-in is shown to be a critical factor in reducing part-to-part variation in part response. Implications for radiation qualification requirements are also explored.

  20. Variability in Measured Space Temperatures in 60 Homes

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, D.; Lay, K.


    This report discusses the observed variability in indoor space temperature in a set of 60 homes located in Florida, New York, Oregon, and Washington. Temperature data were collected at 15-minute intervals for an entire year, including living room, master bedroom, and outdoor air temperature (Arena, et. al). The data were examined to establish the average living room temperature for the set of homes for the heating and cooling seasons, the variability of living room temperature depending on climate, and the variability of indoor space temperature within the homes. The accuracy of software-based energy analysis depends on the accuracy of input values. Thermostat set point is one of the most influential inputs for building energy simulation. Several industry standards exist that recommend differing default thermostat settings for heating and cooling seasons. These standards were compared to the values calculated for this analysis. The data examined for this report show that there is a definite difference between the climates and that the data do not agree well with any particular standard.

  1. Stream temperature variability: why it matters to salmon (United States)

    E. Ashley Steel; Brian Beckman; Marie Oliver


    Salmon evolved in natural river systems, where temperatures fluctuate daily, weekly, seasonally, and all along a stream’s path—from the mountains to the sea. Climate change and human activities alter this natural variability. Dams, for example, tend to reduce thermal fluctuations.Currently, scientists gauge habitat suitability for aquatic species by...

  2. Variability in estuarine water temperature gradients and influence on ...

    African Journals Online (AJOL)

    Structure and variability of water temperature gradients and potential influence on distribution of two tropical zooplankters (the mysid Mesopodopsis africana and the copepod Acartia natalensis) and their temperate congenerics (M. wooldridgei and A. longipatella) was investigated over a 10-year period in the Mgazi Estuary, ...

  3. Human Responses to Climate Variability: The Case of South Africa (United States)

    Oppenheimer, M.; Licker, R.; Mastrorillo, M.; Bohra-Mishra, P.; Estes, L. D.; Cai, R.


    Climate variability has been associated with a range of societal and individual outcomes including migration, violent conflict, changes in labor productivity, and health impacts. Some of these may be direct responses to changes in mean temperature or precipitation or extreme events, such as displacement of human populations by tropical cyclones. Others may be mediated by a variety of biological, social, or ecological factors such as migration in response to long-term changes in crops yields. Research is beginning to elucidate and distinguish the many channels through which climate variability may influence human behavior (ranging from the individual to the collective, societal level) in order to better understand how to improve resilience in the face of current variability as well as future climate change. Using a variety of data sets from South Africa, we show how climate variability has influenced internal (within country) migration in recent history. We focus on South Africa as it is a country with high levels of internal migration and dramatic temperature and precipitation changes projected for the 21st century. High poverty rates and significant levels of rain-fed, smallholder agriculture leave large portions of South Africa's population base vulnerable to future climate change. In this study, we utilize two complementary statistical models - one micro-level model, driven by individual and household level survey data, and one macro-level model, driven by national census statistics. In both models, we consider the effect of climate on migration both directly (with gridded climate reanalysis data) and indirectly (with agricultural production statistics). With our historical analyses of climate variability, we gain insights into how the migration decisions of South Africans may be influenced by future climate change. We also offer perspective on the utility of micro and macro level approaches in the study of climate change and human migration.

  4. Observed Decrease of North American Winter Temperature Variability (United States)

    Rhines, A. N.; Tingley, M.; McKinnon, K. A.; Huybers, P. J.


    There is considerable interest in determining whether temperature variability has changed in recent decades. Model ensembles project that extratropical land temperature variance will detectably decrease by 2070. We use quantile regression of station observations to show that decreasing variability is already robustly detectable for North American winter during 1979--2014. Pointwise trends from GHCND stations are mapped into a continuous spatial field using thin-plate spline regression, resolving small-scales while providing uncertainties accounting for spatial covariance and varying station density. We find that variability of daily temperatures, as measured by the difference between the 95th and 5th percentiles, has decreased markedly in winter for both daily minima and maxima. Composites indicate that the reduced spread of winter temperatures primarily results from Arctic amplification decreasing the meridional temperature gradient. Greater observed warming in the 5th relative to the 95th percentile stems from asymmetric effects of advection during cold versus warm days; cold air advection is generally from northerly regions that have experienced greater warming than western or southwestern regions that are generally sourced during warm days.

  5. Oral temperature and cardiovascular responses of apparently ...

    African Journals Online (AJOL)

    Oral temperature and cardiovascular responses of apparently healthy subjects to passive and active warm-up. BOA Adegoke, OO Ogwumike, FA Maruf. Abstract. This study investigated and compared the effects of active and passive warm-up on oral temperature and cardiovascular parameters of forty (20 males and 20 ...

  6. Temperature transient response measurement in flowing water

    International Nuclear Information System (INIS)

    Rainbird, J.C.


    A specially developed procedure is described for determining the thermal transient response of thermocouples and other temperature transducers when totally immersed in flowing water. The high velocity heat transfer conditions associated with this facility enable thermocouple response times to be predicted in other fluids. These predictions can be confirmed by electrical analogue experiments. (author)

  7. Divergent phenological response to hydroclimate variability in forested mountain watersheds. (United States)

    Hwang, Taehee; Band, Lawrence E; Miniat, Chelcy F; Song, Conghe; Bolstad, Paul V; Vose, James M; Love, Jason P


    Mountain watersheds are primary sources of freshwater, carbon sequestration, and other ecosystem services. There is significant interest in the effects of climate change and variability on these processes over short to long time scales. Much of the impact of hydroclimate variability in forest ecosystems is manifested in vegetation dynamics in space and time. In steep terrain, leaf phenology responds to topoclimate in complex ways, and can produce specific and measurable shifts in landscape forest patterns. The onset of spring is usually delayed at a specific rate with increasing elevation (often called Hopkins' Law; Hopkins, 1918), reflecting the dominant controls of temperature on greenup timing. Contrary with greenup, leaf senescence shows inconsistent trends along elevation gradients. Here, we present mechanisms and an explanation for this variability and its significance for ecosystem patterns and services in response to climate. We use moderate-resolution imaging spectro-radiometer (MODIS) Normalized Difference Vegetation Index (NDVI) data to derive landscape-induced phenological patterns over topoclimate gradients in a humid temperate broadleaf forest in southern Appalachians. These phenological patterns are validated with different sets of field observations. Our data demonstrate that divergent behavior of leaf senescence with elevation is closely related to late growing season hydroclimate variability in temperature and water balance patterns. Specifically, a drier late growing season is associated with earlier leaf senescence at low elevation than at middle elevation. The effect of drought stress on vegetation senescence timing also leads to tighter coupling between growing season length and ecosystem water use estimated from observed precipitation and runoff generation. This study indicates increased late growing season drought may be leading to divergent ecosystem response between high and low elevation forests. Landscape-induced phenological patterns

  8. Soil temperature variability in complex terrain measured using fiber-optic distributed temperature sensing (United States)

    Soil temperature (Ts) exerts critical controls on hydrologic and biogeochemical processes but magnitude and nature of Ts variability in a landscape setting are rarely documented. Fiber optic distributed temperature sensing systems (FO-DTS) potentially measure Ts at high density over a large extent. ...

  9. Bet-hedging response to environmental variability, an intraspecific comparison. (United States)

    Nevoux, Marie; Forcada, Jaume; Barbraud, Christophe; Croxall, John; Weimerskirchi, Henri


    A major challenge in ecology is to understand the impact of increased environmental variability on populations and ecosystems. To maximize their fitness in a variable environment, life history theory states that individuals should favor a bet-hedging strategy, involving a reduction of annual breeding performance and an increase in adult survival so that reproduction can be attempted over more years. As a result, evolution toward longer life span is expected to reduce the deleterious effects of extra variability on population growth, and consequently on the trait contributing the most to it (e.g., adult survival in long-lived species). To investigate this, we compared the life histories of two Black-browed Albatross (Thalassarche melanophrys) populations breeding at South Georgia (Atlantic Ocean) and Kerguelen (Indian Ocean), the former in an environment nearly three times more variable climatically (e.g., in sea surface temperature) than the latter. As predicted, individuals from South Georgia (in the more variable environment) showed significantly higher annual adult survival (0.959, SE = 0.003) but lower annual reproductive success (0.285 chick per pair, SE = 0.039) than birds from Kerguelen (survival = 0.925, SE = 0.004; breeding success = 0.694, SE = 0.027). In both populations, climatic conditions affected the breeding success and the survival of inexperienced breeders, whereas the survival of experienced breeders was unaffected. The strength of the climatic impact on survival of inexperienced breeders was very similar between the two populations, but the effect on breeding success was positively related to environmental variability. These results provide rare and compelling evidence to support bet-hedging underlying changes in life history traits as an adaptive response to environmental variability.

  10. Characterizing Uncertainty In Electrical Resistivity Tomography Images Due To Subzero Temperature Variability (United States)

    Herring, T.; Cey, E. E.; Pidlisecky, A.


    Time-lapse electrical resistivity tomography (ERT) is used to image changes in subsurface electrical conductivity (EC), e.g. due to a saline contaminant plume. Temperature variation also produces an EC response, which interferes with the signal of interest. Temperature compensation requires the temperature distribution and the relationship between EC and temperature, but this relationship at subzero temperatures is not well defined. The goal of this study is to examine how uncertainty in the subzero EC/temperature relationship manifests in temperature corrected ERT images, especially with respect to relevant plume parameters (location, contaminant mass, etc.). First, a lab experiment was performed to determine the EC of fine-grained glass beads over a range of temperatures (-20° to 20° C) and saturations. The measured EC/temperature relationship was then used to add temperature effects to a hypothetical EC model of a conductive plume. Forward simulations yielded synthetic field data to which temperature corrections were applied. Varying the temperature/EC relationship used in the temperature correction and comparing the temperature corrected ERT results to the synthetic model enabled a quantitative analysis of the error of plume parameters associated with temperature variability. Modeling possible scenarios in this way helps to establish the feasibility of different time-lapse ERT applications by quantifying the uncertainty associated with parameter(s) of interest.

  11. Temperature response of soil respiration largely unaltered with experimental warming (United States)

    Carey, Joanna C.; Tang, Jianwu; Templer, Pamela H.; Kroeger, Kevin D.; Crowther, Thomas W.; Burton, Andrew J.; Dukes, Jeffrey S.; Emmett, Bridget; Frey, Serita D.; Heskel, Mary A.; Jiang, Lifen; Machmuller, Megan B.; Mohan, Jacqueline; Panetta, Anne Marie; Reich, Peter B.; Reinsch, Sabine; Wang, Xin; Allison, Steven D.; Bamminger, Chris; Bridgham, Scott; Collins, Scott L.; de Dato, Giovanbattista; Eddy, William C.; Enquist, Brian J.; Estiarte, Marc; Harte, John; Henderson, Amanda; Johnson, Bart R.; Steenberg Larsen, Klaus; Luo, Yiqi; Marhan, Sven; Melillo, Jerry M.; Penuelas, Josep; Pfeifer-Meister, Laurel; Poll, Christian; Rastetter, Edward B.; Reinmann, Andrew B.; Reynolds, Lorien L.; Schmidt, Inger K.; Shaver, Gaius R.; Strong, Aaron L.; Suseela, Vidya; Tietema, Albert


    The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation of soil respiration to experimental warming in several major biome types, contrary to the results from multiple single-site studies. Moreover, across all nondesert biomes, respiration rates with and without experimental warming follow a Gaussian response, increasing with soil temperature up to a threshold of ∼25 °C, above which respiration rates decrease with further increases in temperature. This consistent decrease in temperature sensitivity at higher temperatures demonstrates that rising global temperatures may result in regionally variable responses in soil respiration, with colder climates being considerably more responsive to increased ambient temperatures compared with warmer regions. Our analysis adds a unique cross-biome perspective on the temperature response of soil respiration, information critical to improving our mechanistic understanding of how soil carbon dynamics change with climatic warming.

  12. Interannual variability of north Atlantic Sea surface temperatures

    International Nuclear Information System (INIS)

    Bhatt, U.S.; Battisiti, D.S.; Alexander, M.A.


    In the midlatitude north Atlantic Ocean the pattern of sea surface temperature anomalies (ssta) is characterized by a north-south dipole. Bjerknes was the first to propose that the banded structure was associated with the interannual variability. Recently, these patterns have been studied more extensively. In this study the quantitative aspects of these patterns are examined through the use of a mixed-layer model (MLM)

  13. Coral bleaching pathways under the control of regional temperature variability (United States)

    Langlais, C. E.; Lenton, A.; Heron, S. F.; Evenhuis, C.; Sen Gupta, A.; Brown, J. N.; Kuchinke, M.


    Increasing sea surface temperatures (SSTs) are predicted to adversely impact coral populations worldwide through increasing thermal bleaching events. Future bleaching is unlikely to be spatially uniform. Therefore, understanding what determines regional differences will be critical for adaptation management. Here, using a cumulative heat stress metric, we show that characteristics of regional SST determine the future bleaching risk patterns. Incorporating observed information on SST variability, in assessing future bleaching risk, provides novel options for management strategies. As a consequence, the known biases in climate model variability and the uncertainties in regional warming rate across climate models are less detrimental than previously thought. We also show that the thresholds used to indicate reef viability can strongly influence a decision on what constitutes a potential refugia. Observing and understanding the drivers of regional variability, and the viability limits of coral reefs, is therefore critical for making meaningful projections of coral bleaching risk.

  14. White Dwarfs in Cataclysmic Variable Stars: Surface Temperatures and Evolution

    Directory of Open Access Journals (Sweden)

    Edward M. Sion


    Full Text Available A summary is presented of what is currently known about the surface temperatures of accreting white dwarfs (WDs detected in non-magnetic and magnetic cataclysmic variables (CVs based upon synthetic spectral analyses of far ultraviolet data. A special focus is placed on WD temperatures above and below the CV period gap as a function of the orbital period, Porb. The principal uncertainty of the temperatures for the CV WDs in the Teff - Porb distribution, besides the distance to the CV, is the mass of the WD. Only in eclipsing CV systems, an area of eclipsing binary studies, which was so central to Robert H. Koch’s career, is it possible to know CV WD masses with high precision.

  15. Variability in response to albuminuria-lowering drugs

    DEFF Research Database (Denmark)

    Petrykiv, Sergei I; de Zeeuw, Dick; Persson, Frederik


    AIMS: Albuminuria-lowering drugs have shown different effect size in different individuals. Since urine albumin levels are known to vary considerably from day-to-day, we questioned whether the between-individual variability in albuminuria response after therapy initiation reflects a random...... variability or a true response variation to treatment. In addition, we questioned whether the response variability is drug dependent. METHODS: To determine whether the response to treatment is random or a true drug response, we correlated in six clinical trials the change in albuminuria during placebo...... or active treatment (on-treatment) with the change in albuminuria during wash-out (off-treatment). If these responses correlate during active treatment, it suggests that at least part of the response variability can be attributed to drug response variability. We tested this for enalapril, losartan...

  16. The Temperature and Salinity Variabilities at Cisadane Estuary

    Directory of Open Access Journals (Sweden)



    Full Text Available The study was conducted at Cisadane Estuary at 18 oceanographic station in Transition Monsoon Season I, East Monsoon Season, and Transition Monsoon Season II from 2003 to 2005. The area of the study was located at the longitude of 106.58° - 106.70° E and the latitude of 5.96° - 6.02°S. The measurements of temperature, salinity, tubidity and light transmision used CTD (Conductivity, Temperature and Depth Model SBE-19. The result shows that the temperature and salinity vertical profil variabilities at Cisadane Estuary underwent a change in the influence of Transition Monsoon Season I, East Monsoon Season, and Transition Monsoon Season II, for example it was obtained the leg time of the maximum salinity of Transition Monsoon Season II as the same as that of East Monsoon Season. Based on the horizontal and vertical distribution pattern analysis of the interaction between low salinity fresh water of Cisadane River and high salinity sea water of Java Sea, it was also influenced by the season variability and tide. The surface layer was much more influenced by the low salinity and the heat of sunray (seasonal variability with the weaker intensity to the lower layer. The change of the heat energy by the increase of seasonal temperature occurred in September 2003 to May 2004 ((ΔE = 600.6 ⋅ 105 Joule, July to November 2005 (ΔE = 84.9 Joule. The decrease of the heat energy occurred in June to September 2003 ((-267.6 ⋅ 105, May ke October 2004 (ΔE = 189.3 ⋅ 105 Joule and October 2004 to July 2005 (ΔE = -215.4 ⋅ 105 Joule.

  17. Mesopause region temperature variability and its trend in southern Brazil (United States)

    Venturini, Mateus S.; Bageston, José V.; Caetano, Nattan R.; Peres, Lucas V.; Bencherif, Hassan; Schuch, Nelson J.


    Nowadays, the study of the upper atmosphere is increasing, mostly because of the need to understand the patterns of Earth's atmosphere. Since studies on global warming have become very important for the development of new technologies, understanding all regions of the atmosphere becomes an unavoidable task. In this paper, we aim to analyze the temperature variability and its trend in the mesosphere and lower thermosphere (MLT) region during a period of 12 years (from 2003 to 2014). For this purpose, three different heights, i.e., 85, 90 and 95 km, were focused on in order to investigate the upper atmosphere, and a geographic region different to other studies was chosen, in the southern region of Brazil, centered in the city of Santa Maria, RS (29°41'02'' S; 53°48'25'' W). In order to reach the objectives of this work, temperature data from the SABER instrument (Sounding of the Atmosphere using Broadband Emission Radiometry), aboard NASA's Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) satellite, were used. Finally, two cases were studied related to distinct grids of latitude/longitude used to obtain the mean temperature profiles. The first case considered a grid of 20° × 20° lat/long, centered in Santa Maria, RS, Brazil. In the second case, the region was reduced to a size of 15° × 15° in order to compare the results and discuss the two cases in terms of differences or similarities in temperature trends. Observations show that the size of the geographical area used for the average temperature profiles can influence the results of variability and trend of the temperature. In addition, reducing the time duration of analyses from 24 to 12 h a day also influences the trend significantly. For the smaller geographical region (15° × 15°) and the 12 h daily time window (09:00-21:00 UT) it was found that the main contributions for the temperature variability at the three heights were the annual and semi-annual cycles and the solar flux influence

  18. Intraseasonal sea surface temperature variability in Indonesian seas (United States)

    Napitu, A. M.; Gordon, A. L.; Yuan, X.


    The satellite-derived sea surface temperature (SST) data, 1998-mid 2012, are used to examine intraseasonal variability (ISV; 20-90 days) across the Indonesian seas. The most energetic ISV is observed in the Banda Sea and across the Indo-Australia basin with an The satellite-derived sea surface temperature (SST) data, 1998-mid 2012, are used to examine intraseasonal variability (ISV; 20-90 days) across the Indonesian seas. The most energetic ISV is observed in the Banda Sea and across the Indo-Australia basin with an average SST standard deviation (STD) between 0.4-0.5°C, with strongest signature during boreal winter. What physical processes force the SST ISV variability within the Indonesian seas? Ocean process, sea-air interaction, or both? To help identify the main forcing, the satellite derived outgoing longwave radiation (OLR) and wind stress data in the region are examined. The OLR shows robust intraseasonal variations and is significantly correlated with the SST, particularly for variability with periods of 30-60 days, with OLR accounting for ~60-70% of the SST variance. The OLR is also maximum during boreal winter. Conversely, the surface wind may play insignificant role in perturbing the SST at intraseasonal timescales as shown by weak correlation between wind stress and SST. We thus suspect that the surface solar flux (suggested by the OLR) is likely more dominant than the surface turbulent heat flux (indicated by the surface wind) as the main source for the ISV in the SST in Indonesian seas. Furthermore the maximum OLR phase, coupled with a period of minimum mixed layer depth, may explain the strong SST variation during boreal winter in Indonesian seas. The influence of the Madden-Julian Oscillation (MJO) on the OLR and SST variability is currently being evaluated.

  19. Functional responses of North Atlantic fish eggs to increasing temperature

    DEFF Research Database (Denmark)

    Tsoukali, Stavroula; Visser, Andre; MacKenzie, Brian


    -days and survival of fish eggs from 32 populations of 17 species in the North Atlantic to different temperatures in order to determine potential consequences of global warming for these species. The response of development time exhibited a similar decreasing trend with respect to temperature across species....... There was an overall decrease, across species, in an index of thermal requirement (cumulative degree-days) for egg development with increasing temperature. Within an empirically derived optimal thermal range for egg survival, the thermal requirement was more variable in species adapted to cold waters compared...... to species adapted to warmer waters. Moreover, the sensitivity of survival of eggs from different species to increases in temperature differed, reflecting a pattern of sensitivity along a stenotherm-eurytherm gradient of vulnerability to temperature among species. The results quantify physiological effects...

  20. Taking the pulse of mountains: Ecosystem responses to climatic variability (United States)

    Fagre, Daniel B.; Peterson, David L.; Hessl, Amy E.


    An integrated program of ecosystem modeling and field studies in the mountains of the Pacific Northwest (U.S.A.) has quantified many of the ecological processes affected by climatic variability. Paleoecological and contemporary ecological data in forest ecosystems provided model parameterization and validation at broad spatial and temporal scales for tree growth, tree regeneration and treeline movement. For subalpine tree species, winter precipitation has a strong negative correlation with growth; this relationship is stronger at higher elevations and west-side sites (which have more precipitation). Temperature affects tree growth at some locations with respect to length of growing season (spring) and severity of drought at drier sites (summer). Furthermore, variable but predictable climate-growth relationships across elevation gradients suggest that tree species respond differently to climate at different locations, making a uniform response of these species to future climatic change unlikely. Multi-decadal variability in climate also affects ecosystem processes. Mountain hemlock growth at high-elevation sites is negatively correlated with winter snow depth and positively correlated with the winter Pacific Decadal Oscillation (PDO) index. At low elevations, the reverse is true. Glacier mass balance and fire severity are also linked to PDO. Rapid establishment of trees in subalpine ecosystems during this century is increasing forest cover and reducing meadow cover at many subalpine locations in the western U.S.A. and precipitation (snow depth) is a critical variable regulating conifer expansion. Lastly, modeling potential future ecosystem conditions suggests that increased climatic variability will result in increasing forest fire size and frequency, and reduced net primary productivity in drier, east-side forest ecosystems. As additional empirical data and modeling output become available, we will improve our ability to predict the effects of climatic change

  1. Complexation of Plutonium (IV) With Sulfate At Variable Temperatures

    International Nuclear Information System (INIS)

    Y. Xia; J.I. Friese; D.A. Moore; P.P. Bachelor; L. Rao


    The complexation of plutonium(IV) with sulfate at variable temperatures has been investigated by solvent extraction method. A NaBrO 3 solution was used as holding oxidant to maintain the plutonium(IV) oxidation state throughout the experiments. The distribution ratio of Pu(IV) between the organic and aqueous phases was found to decrease as the concentrations of sulfate were increased. Stability constants of the 1:1 and 1:2 Pu(IV)-HSO 4 - complexes, dominant in the aqueous phase, were calculated from the effect of [HSO 4 - ] on the distribution ratio. The enthalpy and entropy of complexation were calculated from the stability constants at different temperatures using the Van't Hoff equation

  2. Causes of Greenland temperature variability over the past 4000 yr: implications for northern hemispheric temperature changes

    Directory of Open Access Journals (Sweden)

    T. Kobashi


    Full Text Available Precise understanding of Greenland temperature variability is important in two ways. First, Greenland ice sheet melting associated with rising temperature is a major global sea level forcing, potentially affecting large populations in coming centuries. Second, Greenland temperatures are highly affected by North Atlantic Oscillation/Arctic Oscillation (NAO/AO and Atlantic multidecadal oscillation (AMO. In our earlier study, we found that Greenland temperature deviated negatively (positively from northern hemispheric (NH temperature trend during stronger (weaker solar activity owing to changes in atmospheric/oceanic changes (e.g. NAO/AO over the past 800 yr (Kobashi et al., 2013. Therefore, a precise Greenland temperature record can provide important constraints on the past atmospheric/oceanic circulation in the region and beyond. Here, we investigated Greenland temperature variability over the past 4000 yr reconstructed from argon and nitrogen isotopes from trapped air in a GISP2 ice core, using a one-dimensional energy balance model with orbital, solar, volcanic, greenhouse gas, and aerosol forcings. The modelled northern Northern Hemisphere (NH temperature exhibits a cooling trend over the past 4000 yr as observed for the reconstructed Greenland temperature through decreasing annual average insolation. With consideration of the negative influence of solar variability, the modelled and observed Greenland temperatures agree with correlation coefficients of r = 0.34–0.36 (p = 0.1–0.04 in 21 yr running means (RMs and r = 0.38–0.45 (p = 0.1–0.05 on a centennial timescale (101 yr RMs. Thus, the model can explain 14 to 20% of variance of the observed Greenland temperature in multidecadal to centennial timescales with a 90–96% confidence interval, suggesting that a weak but persistent negative solar influence on Greenland temperature continued over the past 4000 yr. Then, we estimated the distribution of multidecadal NH and northern high

  3. Error response test system and method using test mask variable (United States)

    Gender, Thomas K. (Inventor)


    An error response test system and method with increased functionality and improved performance is provided. The error response test system provides the ability to inject errors into the application under test to test the error response of the application under test in an automated and efficient manner. The error response system injects errors into the application through a test mask variable. The test mask variable is added to the application under test. During normal operation, the test mask variable is set to allow the application under test to operate normally. During testing, the error response test system can change the test mask variable to introduce an error into the application under test. The error response system can then monitor the application under test to determine whether the application has the correct response to the error.

  4. Emergent constraint on equilibrium climate sensitivity from global temperature variability. (United States)

    Cox, Peter M; Huntingford, Chris; Williamson, Mark S


    Equilibrium climate sensitivity (ECS) remains one of the most important unknowns in climate change science. ECS is defined as the global mean warming that would occur if the atmospheric carbon dioxide (CO 2 ) concentration were instantly doubled and the climate were then brought to equilibrium with that new level of CO 2 . Despite its rather idealized definition, ECS has continuing relevance for international climate change agreements, which are often framed in terms of stabilization of global warming relative to the pre-industrial climate. However, the 'likely' range of ECS as stated by the Intergovernmental Panel on Climate Change (IPCC) has remained at 1.5-4.5 degrees Celsius for more than 25 years. The possibility of a value of ECS towards the upper end of this range reduces the feasibility of avoiding 2 degrees Celsius of global warming, as required by the Paris Agreement. Here we present a new emergent constraint on ECS that yields a central estimate of 2.8 degrees Celsius with 66 per cent confidence limits (equivalent to the IPCC 'likely' range) of 2.2-3.4 degrees Celsius. Our approach is to focus on the variability of temperature about long-term historical warming, rather than on the warming trend itself. We use an ensemble of climate models to define an emergent relationship between ECS and a theoretically informed metric of global temperature variability. This metric of variability can also be calculated from observational records of global warming, which enables tighter constraints to be placed on ECS, reducing the probability of ECS being less than 1.5 degrees Celsius to less than 3 per cent, and the probability of ECS exceeding 4.5 degrees Celsius to less than 1 per cent.

  5. Emergent constraint on equilibrium climate sensitivity from global temperature variability (United States)

    Cox, Peter M.; Huntingford, Chris; Williamson, Mark S.


    Equilibrium climate sensitivity (ECS) remains one of the most important unknowns in climate change science. ECS is defined as the global mean warming that would occur if the atmospheric carbon dioxide (CO2) concentration were instantly doubled and the climate were then brought to equilibrium with that new level of CO2. Despite its rather idealized definition, ECS has continuing relevance for international climate change agreements, which are often framed in terms of stabilization of global warming relative to the pre-industrial climate. However, the ‘likely’ range of ECS as stated by the Intergovernmental Panel on Climate Change (IPCC) has remained at 1.5-4.5 degrees Celsius for more than 25 years. The possibility of a value of ECS towards the upper end of this range reduces the feasibility of avoiding 2 degrees Celsius of global warming, as required by the Paris Agreement. Here we present a new emergent constraint on ECS that yields a central estimate of 2.8 degrees Celsius with 66 per cent confidence limits (equivalent to the IPCC ‘likely’ range) of 2.2-3.4 degrees Celsius. Our approach is to focus on the variability of temperature about long-term historical warming, rather than on the warming trend itself. We use an ensemble of climate models to define an emergent relationship between ECS and a theoretically informed metric of global temperature variability. This metric of variability can also be calculated from observational records of global warming, which enables tighter constraints to be placed on ECS, reducing the probability of ECS being less than 1.5 degrees Celsius to less than 3 per cent, and the probability of ECS exceeding 4.5 degrees Celsius to less than 1 per cent.

  6. What do foraging wasps optimize in a variable environment, energy investment or body temperature? (United States)

    Kovac, Helmut; Stabentheiner, Anton; Brodschneider, Robert


    Vespine wasps (Vespula sp.) are endowed with a pronounced ability of endothermic heat production. To show how they balance energetics and thermoregulation under variable environmental conditions, we measured the body temperature and respiration of sucrose foragers (1.5 M, unlimited flow) under variable ambient temperature (T a = 20-35 °C) and solar radiation (20-570 W m(-2)). Results revealed a graduated balancing of metabolic efforts with thermoregulatory needs. The thoracic temperature in the shade depended on ambient temperature, increasing from ~37 to 39 °C. However, wasps used solar heat gain to regulate their thorax temperature at a rather high level at low T a (mean T thorax ~ 39 °C). Only at high T a they used solar heat to reduce their metabolic rate remarkably. A high body temperature accelerated the suction speed and shortened foraging time. As the costs of foraging strongly depended on duration, the efficiency could be significantly increased with a high body temperature. Heat gain from solar radiation enabled the wasps to enhance foraging efficiency at high ambient temperature (T a = 30 °C) by up to 63 %. The well-balanced change of economic strategies in response to environmental conditions minimized costs of foraging and optimized energetic efficiency.

  7. Complex terrain influences ecosystem carbon responses to temperature and precipitation (United States)

    Reyes, W. M.; Epstein, H. E.; Li, X.; McGlynn, B. L.; Riveros-Iregui, D. A.; Emanuel, R. E.


    Terrestrial ecosystem responses to temperature and precipitation have major implications for the global carbon cycle. Case studies demonstrate that complex terrain, which accounts for more than 50% of Earth's land surface, can affect ecological processes associated with land-atmosphere carbon fluxes. However, no studies have addressed the role of complex terrain in mediating ecophysiological responses of land-atmosphere carbon fluxes to climate variables. We synthesized data from AmeriFlux towers and found that for sites in complex terrain, responses of ecosystem CO2 fluxes to temperature and precipitation are organized according to terrain slope and drainage area, variables associated with water and energy availability. Specifically, we found that for tower sites in complex terrain, mean topographic slope and drainage area surrounding the tower explained between 51% and 78% of site-to-site variation in the response of CO2 fluxes to temperature and precipitation depending on the time scale. We found no such organization among sites in flat terrain, even though their flux responses exhibited similar ranges. These results challenge prevailing conceptual framework in terrestrial ecosystem modeling that assumes that CO2 fluxes derive from vertical soil-plant-climate interactions. We conclude that the terrain in which ecosystems are situated can also have important influences on CO2 responses to temperature and precipitation. This work has implications for about 14% of the total land area of the conterminous U.S. This area is considered topographically complex and contributes to approximately 15% of gross ecosystem carbon production in the conterminous U.S.

  8. Soil Temperature Variability in Complex Terrain measured using Distributed a Fiber-Optic Distributed Temperature Sensing (United States)

    Seyfried, M. S.; Link, T. E.


    Soil temperature (Ts) exerts critical environmental controls on hydrologic and biogeochemical processes. Rates of carbon cycling, mineral weathering, infiltration and snow melt are all influenced by Ts. Although broadly reflective of the climate, Ts is sensitive to local variations in cover (vegetative, litter, snow), topography (slope, aspect, position), and soil properties (texture, water content), resulting in a spatially and temporally complex distribution of Ts across the landscape. Understanding and quantifying the processes controlled by Ts requires an understanding of that distribution. Relatively few spatially distributed field Ts data exist, partly because traditional Ts data are point measurements. A relatively new technology, fiber optic distributed temperature system (FO-DTS), has the potential to provide such data but has not been rigorously evaluated in the context of remote, long term field research. We installed FO-DTS in a small experimental watershed in the Reynolds Creek Experimental Watershed (RCEW) in the Owyhee Mountains of SW Idaho. The watershed is characterized by complex terrain and a seasonal snow cover. Our objectives are to: (i) evaluate the applicability of fiber optic DTS to remote field environments and (ii) to describe the spatial and temporal variability of soil temperature in complex terrain influenced by a variable snow cover. We installed fiber optic cable at a depth of 10 cm in contrasting snow accumulation and topographic environments and monitored temperature along 750 m with DTS. We found that the DTS can provide accurate Ts data (+/- .4°C) that resolves Ts changes of about 0.03°C at a spatial scale of 1 m with occasional calibration under conditions with an ambient temperature range of 50°C. We note that there are site-specific limitations related cable installation and destruction by local fauna. The FO-DTS provide unique insight into the spatial and temporal variability of Ts in a landscape. We found strong seasonal

  9. Disentangling Global Warming, Multidecadal Variability, and El Niño in Pacific Temperatures (United States)

    Wills, Robert C.; Schneider, Tapio; Wallace, John M.; Battisti, David S.; Hartmann, Dennis L.


    A key challenge in climate science is to separate observed temperature changes into components due to internal variability and responses to external forcing. Extended integrations of forced and unforced climate models are often used for this purpose. Here we demonstrate a novel method to separate modes of internal variability from global warming based on differences in time scale and spatial pattern, without relying on climate models. We identify uncorrelated components of Pacific sea surface temperature variability due to global warming, the Pacific Decadal Oscillation (PDO), and the El Niño-Southern Oscillation (ENSO). Our results give statistical representations of PDO and ENSO that are consistent with their being separate processes, operating on different time scales, but are otherwise consistent with canonical definitions. We isolate the multidecadal variability of the PDO and find that it is confined to midlatitudes; tropical sea surface temperatures and their teleconnections mix in higher-frequency variability. This implies that midlatitude PDO anomalies are more persistent than previously thought.

  10. Tropical sea surface temperature variability near the Oligocene - Miocene boundary (United States)

    Zhang, Y.; Pagani, M.


    The Oligocene/Miocene (O-M) boundary is characterized by a period of rapid and intense glaciation labeled Mi-1 at ~ 23.1 Ma. An abrupt 1.5‰ increase in the benthic foraminifera oxygen isotope composition that characterizes Mi-1 may indicate a (1) significant deep-water temperature decrease; (2) major ice-sheet expansion, or the combination of both. Current coarse Mg/Ca-based temperature estimations for the early Miocene suggests that deep-ocean temperatures were ~2°C warmer than Today [1, 2]. However, Mg/Ca based temperatures can also be influenced by changes in the carbonate ion concentration, vital effects, and diagenesis. In particular, recent evidence from mid-ocean ridge flank carbonate veins shows dramatic seawater Mg/Ca ratio changes during the Neogene (Mg/Ca from ~2.2 to 5.3, [3]), which further challenges the application of Mg/Ca thermometry. Owing to poor temperature constraints, current ice volume estimations for the late Oligocene/early Miocene range from 125% of the present-day East Antarctic Ice Sheet (EAIS) to a nearly complete collapse of the Antarctic glaciers [4]. Here we present tropical sea surface temperatures (SSTs) records based on TEX86 and alkenone UK37 near the O-M boundary. Sediment samples from Ocean Drilling Program (ODP) Site 926 in the Ceara Rise (tropical Atlantic) and Site 1148 in the South China Sea (tropical Pacific) were subject to lipid extraction, separation, gas chromatography, and liquid chromatography-mass spectrometry analysis. TEX86-based SST indicates that the tropics were ~3-4°C warmer than today and relatively stable during Mi-1. This suggests that ice-sheet dynamics, rather than temperature, might be responsible for the observed oxygen isotope changes during the O-M boundary. Further, O-M boundary averaged temperatures recorded at site 926 is ~ 0.5°C higher relative to the late Eocene from site 925 (a nearby site [5]). Given late Oligocene benthic δ18O that suggests at least 1‰ enrichment relative to the late

  11. Elucidating the impact of temperature variability and extremes on cereal croplands through remote sensing. (United States)

    Duncan, John M A; Dash, Jadunandan; Atkinson, Peter M


    Remote sensing-derived wheat crop yield-climate models were developed to highlight the impact of temperature variation during thermo-sensitive periods (anthesis and grain-filling; TSP) of wheat crop development. Specific questions addressed are: can the impact of temperature variation occurring during the TSP on wheat crop yield be detected using remote sensing data and what is the impact? Do crop critical temperature thresholds during TSP exist in real world cropping landscapes? These questions are tested in one of the world's major wheat breadbaskets of Punjab and Haryana, north-west India. Warming average minimum temperatures during the TSP had a greater negative impact on wheat crop yield than warming maximum temperatures. Warming minimum and maximum temperatures during the TSP explain a greater amount of variation in wheat crop yield than average growing season temperature. In complex real world cereal croplands there was a variable yield response to critical temperature threshold exceedance, specifically a more pronounced negative impact on wheat yield with increased warming events above 35 °C. The negative impact of warming increases with a later start-of-season suggesting earlier sowing can reduce wheat crop exposure harmful temperatures. However, even earlier sown wheat experienced temperature-induced yield losses, which, when viewed in the context of projected warming up to 2100 indicates adaptive responses should focus on increasing wheat tolerance to heat. This study shows it is possible to capture the impacts of temperature variation during the TSP on wheat crop yield in real world cropping landscapes using remote sensing data; this has important implications for monitoring the impact of climate change, variation and heat extremes on wheat croplands. © 2014 John Wiley & Sons Ltd.

  12. Promoting Response Variability and Stimulus Generalization in Martial Arts Training (United States)

    Harding, Jay W.; Wacker, David P.; Berg, Wendy K.; Rick, Gary; Lee, John F.


    The effects of reinforcement and extinction on response variability and stimulus generalization in the punching and kicking techniques of 2 martial arts students were evaluated across drill and sparring conditions. During both conditions, the students were asked to demonstrate different techniques in response to an instructor's punching attack.…

  13. Avian community responses to variability in river hydrology. (United States)

    Royan, Alexander; Hannah, David M; Reynolds, S James; Noble, David G; Sadler, Jonathan P


    River flow is a major driver of morphological structure and community dynamics in riverine-floodplain ecosystems. Flow influences in-stream communities through changes in water velocity, depth, temperature, turbidity and nutrient fluxes, and perturbations in the organisation of lower trophic levels are cascaded through the food web, resulting in shifts in food availability for consumer species. River birds are sensitive to spatial and phenological mismatches with aquatic prey following flow disturbances; however, the role of flow as a determinant of riparian ecological structure remains poorly known. This knowledge is crucial to help to predict if, and how, riparian communities will be influenced by climate-induced changes in river flow characterised by more extreme high (i.e. flood) and/or low (i.e. drought) flow events. Here, we combine national-scale datasets of river bird surveys and river flow archives to understand how hydrological disturbance has affected the distribution of riparian species at higher trophic levels. Data were analysed for 71 river locations using a Generalized Additive Model framework and a model averaging procedure. Species had complex but biologically interpretable associations with hydrological indices, with species' responses consistent with their ecology, indicating that hydrological-disturbance has implications for higher trophic levels in riparian food webs. Our quantitative analysis of river flow-bird relationships demonstrates the potential vulnerability of riparian species to the impacts of changing flow variability and represents an important contribution in helping to understand how bird communities might respond to a climate change-induced increase in the intensity of floods and droughts. Moreover, the success in relating parameters of river flow variability to species' distributions highlights the need to include river flow data in climate change impact models of species' distributions.

  14. Pavement Response to Variable Tyre Pressure of Heavy Vehicles

    Directory of Open Access Journals (Sweden)

    Arshad Ahmad Kamil


    Full Text Available In recent years, the effect of overinflated tyre pressure and increased heavy vehicles’ axle load on flexible pavements has become a subject of great concern because of the higher stress levels induced and damage caused to road pavements. This paper aims to evaluate the effect of variable tyre inflation pressures (using actual tyre contact/footprint area to determine the responses of flexible pavement. A full scale experiment was conducted on a heavy vehicle with 1:1:2 axle configuration, 10 R 20 tyre size and attached trailer with constant axle load. Measurements were made for actual tyre-pavement contact area. KENPAVE linear elastic program was then used to analyse the effects of the measured actual tyre-pavement contact area and the results was compared using conventional circular tyre contact area. A comparative analysis was then made between the actual contact area and the conventional circular tyre contact area. It was found that high tyre inflation pressure produce smaller contact area, giving more detrimental effect on the flexible pavement. It was also found that the temperature of tyres when the heavy vehicles are operational give less significant impact on tyre inflation pressure for the Malaysian climate.

  15. Responses of Montane Forest to Climate Variability in the Central Himalayas of Nepal

    Directory of Open Access Journals (Sweden)

    Janardan Mainali


    Full Text Available Climate changes are having dramatic ecological impacts in mid- to high-latitude mountain ranges where growth conditions are limited by climatic variables such as duration of growing season, moisture, and ambient temperature. We document patterns of forest vegetative response for 5 major alpine forest communities to current climate variability in the central Himalayas of Nepal to provide a baseline for assessment of future changes, as well as offer some insight into the trajectory of these changes over time. We used mean monthly surface air temperature and rainfall and the monthly averaged normalized difference vegetation index (NDVI to compare relative vegetation productivity among forest types and in relation to both climatic variables. Because changes in temperature and precipitation are directly manifested as changes in phenology, we examined current vegetative responses to climate variability in an effort to determine which climate variable is most critical for different alpine forest types. Our results show that correlations differ according to vegetation type and confirm that both precipitation and temperature affect monthly NDVI values, though more significant correlations were found with temperature data. The temperature response was more consistent because at the maximum increased temperatures, there was still an ongoing increase in vegetative vigor. This indicates that temperature is still the major limiting factor for plant growth at higher-elevation sites. This part of the Himalayas has abundant moisture, and some forest types are already saturated in terms of growth in relation to precipitation. Clear increases in productivity are documented on the upper treeline ecotones, and these systems are likely to continue to have increasing growth rates.

  16. Barn Owl Productivity Response to Variability of Vole Populations.

    Directory of Open Access Journals (Sweden)

    Petr Pavluvčík

    Full Text Available We studied the response of the barn owl annual productivity to the common vole population numbers and variability to test the effects of environmental stochasticity on their life histories. Current theory predicts that temporal environmental variability can affect long-term nonlinear responses (e.g., production of young both positively and negatively, depending on the shape of the relationship between the response and environmental variables. At the level of the Czech Republic, we examined the shape of the relationship between the annual sum of fledglings (annual productivity and vole numbers in both non-detrended and detrended data. At the districts' level, we explored whether the degree of synchrony (measured by the correlation coefficient and the strength of the productivity response increase (measured by the regression coefficient in areas with higher vole population variability measured by the s-index. We found that the owls' annual productivity increased linearly with vole numbers in the Czech Republic. Furthermore, based on district data, we also found that synchrony between dynamics in owls' reproductive output and vole numbers increased with vole population variability. However, the strength of the response was not affected by the vole population variability. Additionally, we have shown that detrending remarkably increases the Taylor's exponent b relating variance to mean in vole time series, thereby reversing the relationship between the coefficient of variation and the mean. This shift was not responsible for the increased synchrony with vole population variability. Instead, we suggest that higher synchrony could result from high food specialization of owls on the common vole in areas with highly fluctuating vole populations.

  17. Exploiting temporal variability to understand tree recruitment response to climate change (United States)

    Ines Ibanez; James S. Clark; Shannon LaDeau; Janneke Hill Ris Lambers


    Predicting vegetation shifts under climate change is a challenging endeavor, given the complex interactions between biotic and abiotic variables that influence demographic rates. To determine how current trends and variation in climate change affect seedling establishment, we analyzed demographic responses to spatiotemporal variation to temperature and soil moisture in...

  18. Variability of emissivity and surface temperature over a sparsely vegetated surface

    International Nuclear Information System (INIS)

    Humes, K.S.; Kustas, W.P.; Moran, M.S.; Nichols, W.D.; Weltz, M.A.


    Radiometric surface temperatures obtained from remote sensing measurements are a function of both the physical surface temperature and the effective emissivity of the surface within the band pass of the radiometric measurement. For sparsely vegetated areas, however, a sensor views significant fractions of both bare soil and various vegetation types. In this case the radiometric response of a sensor is a function of the emissivities and kinetic temperatures of various surface elements, the proportion of those surface elements within the field of view of the sensor, and the interaction of radiation emitted from the various surface components. In order to effectively utilize thermal remote sensing data to quantify energy balance components for a sparsely vegetated area, it is important to examine the typical magnitude and degree of variability of emissivity and surface temperature for such surfaces. Surface emissivity measurements and ground and low-altitude-aircraft-based surface temperature measurements (8-13 micrometer band pass) made in conjunction with the Monsoon '90 field experiment were used to evaluate the typical variability of those quantities during the summer rainy season in a semiarid watershed. The average value for thermal band emissivity of the exposed bare soil portions of the surface was found to be approximately 0.96; the average value measured for most of the varieties of desert shrubs present was approximately 0.99. Surface composite emissivity was estimated to be approximately 0.98 for both the grass-dominated and shrub-dominated portions of the watershed. The spatial variability of surface temperature was found to be highly dependent on the spatial scale of integration for the instantaneous field of view (IFOV) of the instrument, the spatial scale of the total area under evaluation, and the time of day

  19. Groundwater level responses to precipitation variability in Mediterranean insular aquifers (United States)

    Lorenzo-Lacruz, Jorge; Garcia, Celso; Morán-Tejeda, Enrique


    Groundwater is one of the largest and most important sources of fresh water on many regions under Mediterranean climate conditions, which are exposed to large precipitation variability that includes frequent meteorological drought episodes, and present high evapotranspiration rates and water demand during the dry season. The dependence on groundwater increases in those areas with predominant permeable lithologies, contributing to aquifer recharge and the abundance of ephemeral streams. The increasing pressure of tourism on water resources in many Mediterranean coastal areas, and uncertainty related to future precipitation and water availability, make it urgent to understand the spatio-temporal response of groundwater bodies to precipitation variability, if sustainable use of the resource is to be achieved. We present an assessment of the response of aquifers to precipitation variability based on correlations between the Standardized Precipitation Index (SPI) at various time scales and the Standardized Groundwater Index (SGI) across a Mediterranean island. We detected three main responses of aquifers to accumulated precipitation anomalies: (i) at short time scales of the SPI (24 months). The differing responses were mainly explained by differences in lithology and the percentage of highly permeable rock strata in the aquifer recharge areas. We also identified differences in the months and seasons when aquifer storages are more dependent on precipitation; these were related to climate seasonality and the degree of aquifer exploitation or underground water extraction. The recharge of some aquifers, especially in mountainous areas, is related to precipitation variability within a limited spatial extent, whereas for aquifers located in the plains, precipitation variability influence much larger areas; the topography and geological structure of the island explain these differences. Results indicate large spatial variability in the response of aquifers to precipitation in

  20. Individual canine Airway Response Variability to a Deep Inspiration

    Directory of Open Access Journals (Sweden)

    Robert H. Brown


    Full Text Available In healthy individuals, a DI can reverse (bronchodilation or prevent (bronchoprotection induced airway constriction. For individuals with asthma or COPD, these effects may be attenuated or absent. Previous work showed that the size and duration of a DI affected the subsequent response of the airways. Also, increased airway tone lead to increased airway size variability. The present study examined how a DI affected the temporal variability in individual airway baseline size and after methacholine challenge in dogs using High-Resolution Computed Tomography. Dogs were anesthetized and ventilated, and on 4 separate days, HRCT scans were acquired before and after a DI at baseline and during a continuous intravenous infusion of methacholine (Mch at 3 dose rates (17, 67, and 200 μg/mm. The Coefficient of Variation was used as an index of temporal variability in airway size. We found that at baseline and the lowest dose of Mch, variability decreased immediately and 5 minutes after the DI ( P < 0.0001. In contrast, with higher doses of Mch, the DI caused a variable response. At a rate of 67 μg/min of Mch, the temporal variability increased after 5 minutes, while at a rate of 200 μg/min of Mch, the temporal variability increased immediately after the DI. Increased airway temporal variability has been shown to be associated with asthma. Although the mechanisms underlying this temporal variability are poorly understood, the beneficial effects of a DI to decrease airway temporal variability was eliminated when airway tone was increased. If this effect is absent in asthmatics, this may suggest a possible mechanism for the loss of bronchoprotective and bronchodilatory effects after a DI in asthma.

  1. Temperature extremes in Europe: mechanisms and responses to climatic change

    International Nuclear Information System (INIS)

    Cattiaux, Julien


    Europe witnessed a spate of record-breaking warm seasons during the 2000's. As illustrated by the devastating heat-wave of the summer 2003, these episodes induced strong societal and environmental impacts. Such occurrence of exceptional events over a relatively short time period raised up many questionings in the present context of climate change. In particular, can recent temperature extremes be considered as 'previews' of future climate conditions? Do they result from an increasing temperature variability? These questions constitute the main motivations of this thesis. Thus, our work aims to contribute to the understanding of physical mechanisms responsible for seasonal temperature extremes in Europe, in order to anticipate their future statistical characteristics. Involved processes are assessed by both statistical data-analysis of observations and climate projections and regional modeling experiments. First we show that while the inter-annual European temperature variability appears driven by disturbances in the North-Atlantic dynamics, the recent warming is likely to be dissociated with potential circulation changes. This inconsistency climaxes during the exceptionally mild autumn of 2006, whose temperature anomaly is only half explained by the atmospheric flow. Recent warm surface conditions in the North-Atlantic ocean seem to substantially contribute to the European warming in autumn-winter, through the establishment of advective and radiative processes. In spring-summer, since both advection by the westerlies and Atlantic warming are reduced, more local processes appear predominant (e.g. soil moisture, clouds, aerosols). Then the issue of future evolution of the relationship between North-Atlantic dynamics and European temperatures is addressed, based on climate projections of the International Panel on Climate Change. Multi-model analysis, using both flow-analogues and weather regimes methods, show that the inconsistency noticed over recent decades is

  2. A plant's perspective of extremes: terrestrial plant responses to changing climatic variability. (United States)

    Reyer, Christopher P O; Leuzinger, Sebastian; Rammig, Anja; Wolf, Annett; Bartholomeus, Ruud P; Bonfante, Antonello; de Lorenzi, Francesca; Dury, Marie; Gloning, Philipp; Abou Jaoudé, Renée; Klein, Tamir; Kuster, Thomas M; Martins, Monica; Niedrist, Georg; Riccardi, Maria; Wohlfahrt, Georg; de Angelis, Paolo; de Dato, Giovanbattista; François, Louis; Menzel, Annette; Pereira, Marízia


    We review observational, experimental, and model results on how plants respond to extreme climatic conditions induced by changing climatic variability. Distinguishing between impacts of changing mean climatic conditions and changing climatic variability on terrestrial ecosystems is generally underrated in current studies. The goals of our review are thus (1) to identify plant processes that are vulnerable to changes in the variability of climatic variables rather than to changes in their mean, and (2) to depict/evaluate available study designs to quantify responses of plants to changing climatic variability. We find that phenology is largely affected by changing mean climate but also that impacts of climatic variability are much less studied, although potentially damaging. We note that plant water relations seem to be very vulnerable to extremes driven by changes in temperature and precipitation and that heat-waves and flooding have stronger impacts on physiological processes than changing mean climate. Moreover, interacting phenological and physiological processes are likely to further complicate plant responses to changing climatic variability. Phenological and physiological processes and their interactions culminate in even more sophisticated responses to changing mean climate and climatic variability at the species and community level. Generally, observational studies are well suited to study plant responses to changing mean climate, but less suitable to gain a mechanistic understanding of plant responses to climatic variability. Experiments seem best suited to simulate extreme events. In models, temporal resolution and model structure are crucial to capture plant responses to changing climatic variability. We highlight that a combination of experimental, observational, and/or modeling studies have the potential to overcome important caveats of the respective individual approaches. © 2012 Blackwell Publishing Ltd.

  3. A plant’s perspective of extremes: Terrestrial plant responses to changing climatic variability (United States)

    Reyer, C.; Leuzinger, S.; Rammig, A.; Wolf, A.; Bartholomeus, R. P.; Bonfante, A.; de Lorenzi, F.; Dury, M.; Gloning, P.; Abou Jaoudé, R.; Klein, T.; Kuster, T. M.; Martins, M.; Niedrist, G.; Riccardi, M.; Wohlfahrt, G.; de Angelis, P.; de Dato, G.; François, L.; Menzel, A.; Pereira, M.


    We review observational, experimental and model results on how plants respond to extreme climatic conditions induced by changing climatic variability. Distinguishing between impacts of changing mean climatic conditions and changing climatic variability on terrestrial ecosystems is generally underrated in current studies. The goals of our review are thus (1) to identify plant processes that are vulnerable to changes in the variability of climatic variables rather than to changes in their mean, and (2) to depict/evaluate available study designs to quantify responses of plants to changing climatic variability. We find that phenology is largely affected by changing mean climate but also that impacts of climatic variability are much less studied but potentially damaging. We note that plant water relations seem to be very vulnerable to extremes driven by changes in temperature and precipitation and that heatwaves and flooding have stronger impacts on physiological processes than changing mean climate. Moreover, interacting phenological and physiological processes are likely to further complicate plant responses to changing climatic variability. Phenological and physiological processes and their interactions culminate in even more sophisticated responses to changing mean climate and climatic variability at the species and community level. Generally, observational studies are well suited to study plant responses to changing mean climate, but less suitable to gain a mechanistic understanding of plant responses to climatic variability. Experiments seem best suited to simulate extreme events. In models, temporal resolution and model structure are crucial to capture plant responses to changing climatic variability. We highlight that a combination of experimental, observational and /or modeling studies have the potential to overcome important caveats of the respective individual approaches. PMID:23504722

  4. Interannual variability of sea surface temperature and circulation in ...

    African Journals Online (AJOL)

    Local surface heat flux exchanges driven by the anomalous shortwave radiation dominated the interannual SST variability in the Tanzanian shelf region, with some contribution by the advection of heat anomalies from the North-East Madagascar Current. Farther offshore, the interannual variability of the SST was dominated ...

  5. Mahalanobis distance and variable selection to optimize dose response

    International Nuclear Information System (INIS)

    Moore, D.H. II; Bennett, D.E.; Wyrobek, A.J.; Kranzler, D.


    A battery of statistical techniques are combined to improve detection of low-level dose response. First, Mahalanobis distances are used to classify objects as normal or abnormal. Then the proportion classified abnormal is regressed on dose. Finally, a subset of regressor variables is selected which maximizes the slope of the dose response line. Use of the techniques is illustrated by application to mouse sperm damaged by low doses of x-rays

  6. Heart Rate Variability: Effect of Exercise Intensity on Postexercise Response (United States)

    James, David V. B.; Munson, Steven C.; Maldonado-Martin, Sara; De Ste Croix, Mark B. A.


    The purpose of the present study was to investigate the influence of two exercise intensities (moderate and severe) on heart rate variability (HRV) response in 16 runners 1 hr prior to (-1 hr) and at +1 hr, +24 hr, +48 hr, and +72 hr following each exercise session. Time domain indexes and a high frequency component showed a significant decrease…

  7. Understanding Farmers' Response to Climate Variability in Nigeria ...

    African Journals Online (AJOL)

    In this study, farmers 'response to climate variability was examined. Primary and secondary data were used. A multi-stage sampling procedure was adopted in the collection of the primary data using structured questionnaires. Four vegetation zones out of seven where farming is mainly carried out were selected for the study.

  8. Kinetic Modeling of Corn Fermentation with S. cerevisiae Using a Variable Temperature Strategy

    Directory of Open Access Journals (Sweden)

    Augusto C. M. Souza


    Full Text Available While fermentation is usually done at a fixed temperature, in this study, the effect of having a controlled variable temperature was analyzed. A nonlinear system was used to model batch ethanol fermentation, using corn as substrate and the yeast Saccharomyces cerevisiae, at five different fixed and controlled variable temperatures. The lower temperatures presented higher ethanol yields but took a longer time to reach equilibrium. Higher temperatures had higher initial growth rates, but the decay of yeast cells was faster compared to the lower temperatures. However, in a controlled variable temperature model, the temperature decreased with time with the initial value of 40 ∘ C. When analyzing a time window of 60 h, the ethanol production increased 20% compared to the batch with the highest temperature; however, the yield was still 12% lower compared to the 20 ∘ C batch. When the 24 h’ simulation was analyzed, the controlled model had a higher ethanol concentration compared to both fixed temperature batches.

  9. Kinetic Modeling of Corn Fermentation with S. cerevisiae Using a Variable Temperature Strategy. (United States)

    Souza, Augusto C M; Mousaviraad, Mohammad; Mapoka, Kenneth O M; Rosentrater, Kurt A


    While fermentation is usually done at a fixed temperature, in this study, the effect of having a controlled variable temperature was analyzed. A nonlinear system was used to model batch ethanol fermentation, using corn as substrate and the yeast Saccharomyces cerevisiae , at five different fixed and controlled variable temperatures. The lower temperatures presented higher ethanol yields but took a longer time to reach equilibrium. Higher temperatures had higher initial growth rates, but the decay of yeast cells was faster compared to the lower temperatures. However, in a controlled variable temperature model, the temperature decreased with time with the initial value of 40 ∘ C. When analyzing a time window of 60 h, the ethanol production increased 20% compared to the batch with the highest temperature; however, the yield was still 12% lower compared to the 20 ∘ C batch. When the 24 h’ simulation was analyzed, the controlled model had a higher ethanol concentration compared to both fixed temperature batches.

  10. Seasonal variability in Arctic temperatures during the early Eocene (United States)

    Eberle, J. J.; Fricke, H. C.; Humphrey, J.; Hackett, L.; Newbrey, M.; Hutchison, H.


    As a deep time analog for today’s rapidly warming Arctic region, early Eocene (~53 Ma) rocks on Ellesmere Island, Arctic Canada (~79° N.) preserve evidence of lush swamp forests inhabited by turtles, alligators, primates, tapirs, and hippo-like Coryphodon. Although the rich flora and fauna of the early Eocene Arctic imply warmer, wetter conditions that at present, quantitative estimates of Eocene Arctic climate are rare. By analyzing oxygen isotope ratios of biogenic phosphate from mammal, fish, and turtle fossils from a single locality on central Ellesmere Island, we provide estimates of early Eocene Arctic temperature, including mean annual temperature (MAT) of ~ 8° C, mean annual range in temperature (MART) of ~ 16.5° C, warm month mean temperature (WMMT) of 16 - 19° C, and cold month mean temperature (CMMT) of 0 - 1° C. Our seasonal range in temperature is similar to the range in estimated MAT obtained using different proxies. In particular, unusually high estimates of early Eocene Arctic MAT and sea surface temperature (SST) by others that are based upon the distribution of branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in terrestrial soil bacteria and marine Crenarchaeota fall within our range of WMMT, suggesting a bias towards summer values. Consequently, caution should be taken when using these methods to infer MAT and SST that, in turn, are used to constrain climate models. From a paleontologic perspective, our temperature estimates verify that alligators and tortoises, by way of nearest living relative-based climatic inference, are viable paleoclimate proxies for mild, above-freezing year-round temperatures. Although in both of these reptiles, past temperature tolerances were greater than in their living descendants.

  11. Processes of India's offshore summer intraseasonal sea surface temperature variability

    Digital Repository Service at National Institute of Oceanography (India)

    Kurian, N.; Lengaigne, M.; Gopalakrishna, V.V.; Vialard, J.; Pous, S.; Peter, A-C.; Durand, F.; Naik, Shweta

    study, we use an eddy-permitting 0.25 degrees regional ocean model to investigate mechanisms of this offshore intraseasonal SST variability. Modelled climatological mixed layer and upper thermocline depth are in very good agreement with estimates from...

  12. A study of the variability in the febrile responses of rabbits to endogenous pyrogen. (United States)

    Stitt, J T


    The range of body temperature increases elicited by a standard dose of endogenous pyrogen (0.5 ml/kg iv) was examined in a population of 26 male New Zealand White rabbits. Although the mean maximum increase in rectal temperature was 0.88 +/- 0.06 degree C (SE), individual responses varied from 0.4 degree to 1.5 degree C. Three representative animals that responded to the standard dose of pyrogen with small, intermediate, and large febrile responses were selected and challenged with the same dose of pyrogen on eight separate occasions, and the variability of these responses was examined. There was little variability within the characteristic responses of any particular animal to the repeated challenges. The variability of the febrile responses elicited by both intravenous and intracerebroventricular administration of the same pyrogen was examined and compared using another group of 11 rabbits. The variability in response to the intravenous route was similar to that found in the larger population, whereas the variation in response to the intracerebroventricular route was smaller, and all 11 animals had fevers that were greater than 1 degrees C. It is concluded that the variability of the febrile responses of rabbits to intravenous pyrogen was due to differences between individual sensitivities of animals to the intravenously administered pyrogen. This difference in sensitivity may be due to a difference in the amount of pyrogen that reaches the putative receptor sites, or to a difference in the density or effectiveness of receptor sites in translating the pyrogenic stimulus into a fever response.

  13. TRLFS Study of U(VI) at Variable Temperatures

    International Nuclear Information System (INIS)

    Lee, J. Y.; Yun, J. I.


    Uranium is one of the most important radionuclides in a nuclear waste repository. Transport phenomena for radioactive elements are of crucial importance for a safe geological disposal of nuclear waste. Chemical speciation and solubility are used for understanding and predicting radionuclides migration in aquifer system. Decay heat released from high level waste and geothermal temperature gradient cause higher temperature above room temperature in deep geologic formation. However, most chemical thermodynamic data are obtained at room temperature until recently. There are few studies at temperatures above 25 .deg. C. Therefore, a better understanding of thermodynamic properties at high temperatures is necessary for reliable safety assessment of high level waste repositories. Time-resolved laser-induced fluorescence spectroscopy (TRLFS) has been applied as a sensitive and selective method for chemical speciation. The fluorescence spectrum is unique for each chemical species. The duration time of fluorescence emission is used as another indicator for decomposition of overlapped fluorescence spectrum. The objective of this study is to investigate fluorescence properties of uranium hydrolysis species at elevated temperature using TRLFS

  14. The river temperature changes follows the climate variability

    International Nuclear Information System (INIS)

    Gergov, G.; Karagiozova, Tz.


    The temperature of the river water is a dynamical characteristic affected by the geophysical processes- and climate characteristics of the catchment area, as well as the hydrological processes of the runoff formation and movement. The knowledge about the river water is very important when the water losses for transpiration are concerned. One should add that the river pollution problems, the self purification, the potable water supply require this information also. We consider the temperature of the river water as a very important parameter for diversity of ecological studies and research. It is a general practice to accept that the river water temperature is rather homogeneous across any profile because of the turbulent mass exchange. The temperature stratification is a matter of concern in limnology and oceanology studies mainly. We have shown several basic regularities about the cyclic feature of the daily and seasonal changes or about the river water temperature and both the altitude of the catchment area (gradient 1 o C per a 100 m) and so on. After the mean water temperatures on any hydro metric gauge stations are being determined the area patterns with equal temperatures are identified, thus drawing a map. It is a presumption that the river water temperatures inside a specific area are equal on any place, meaning that the temperature field is rather homogeneous. The mapping allowed to distinguish the river reaches, subjected to the anthropogenic impact. The study and the map have been developed on the basis of the new hydro metric information data bank, composed recently by the authors.(Author)

  15. Response-rate differences in variable-interval and variable-ratio schedules: An old problem revisited


    Cole, Mark R.


    In Experiment 1, a variable-ratio 10 schedule became, successively, a variable-interval schedule with only the minimum interreinforcement intervals yoked to the variable ratio, or a variable-interval schedule with both interreinforcement intervals and reinforced interresponse times yoked to the variable ratio. Response rates in the variable-interval schedule with both interreinforcement interval and reinforced interresponse time yoking fell between the higher rates maintained by the variable-...

  16. Variable reflectivity signal mirrors and signal response measurements

    International Nuclear Information System (INIS)

    Vine, Glenn de; Shaddock, Daniel A; McClelland, David E


    Future gravitational wave detectors will include some form of signal mirror in order to alter the signal response of the device. We introduce interferometer configurations which utilize a variable reflectivity signal mirror allowing a tunable peak frequency and variable signal bandwidth. A detector configured with a Fabry-Perot cavity as the signal mirror is compared theoretically with one using a Michelson interferometer for a signal mirror. A system for the measurement of the interferometer signal responses is introduced. This technique is applied to a power-recycled Michelson interferometer with resonant sideband extraction. We present broadband measurements of the benchtop prototype's signal response for a range of signal cavity detunings. This technique is also applicable to most other gravitational wave detector configurations

  17. Variable reflectivity signal mirrors and signal response measurements

    CERN Document Server

    Vine, G D; McClelland, D E


    Future gravitational wave detectors will include some form of signal mirror in order to alter the signal response of the device. We introduce interferometer configurations which utilize a variable reflectivity signal mirror allowing a tunable peak frequency and variable signal bandwidth. A detector configured with a Fabry-Perot cavity as the signal mirror is compared theoretically with one using a Michelson interferometer for a signal mirror. A system for the measurement of the interferometer signal responses is introduced. This technique is applied to a power-recycled Michelson interferometer with resonant sideband extraction. We present broadband measurements of the benchtop prototype's signal response for a range of signal cavity detunings. This technique is also applicable to most other gravitational wave detector configurations.

  18. Variable temperature investigation of the atomic structure of gold nanoparticles

    International Nuclear Information System (INIS)

    Young, N P; Kirkland, A I; Huis, M A van; Zandbergen, H W; Xu, H


    The characterisation of nanoparticle structures is the first step towards understanding and optimising their utility in important technological applications such as catalysis. Using newly developed in-situ transmission electron microscopy (TEM) specimen holders, the temperature dependent atomic structure of gold nanoparticles in the size range 5-12 nm has been investigated. In this size interval, the decahedral morphology has been identified as the most favourable structure at or above room temperature, while particle surface roughening becomes evident above 600 0 C. An icosahedral transition has also been identified at low temperature in particles under 9 nm in diameter. These experimental results are consistent with recently published temperature dependent equilibrium phase maps for gold nanoparticles.

  19. Variable temperature investigation of the atomic structure of gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Young, N P; Kirkland, A I [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Huis, M A van; Zandbergen, H W [Kavli Insitute of Nanoscience, Delft University of Technolgy, Lorentzweg 1, NL-2628CJ, Delft (Netherlands); Xu, H, E-mail: [Department of Geology and Geophysics, and Materials Science Program, University of Wisconsin-Madison, Madison, Wisconsin (United States)


    The characterisation of nanoparticle structures is the first step towards understanding and optimising their utility in important technological applications such as catalysis. Using newly developed in-situ transmission electron microscopy (TEM) specimen holders, the temperature dependent atomic structure of gold nanoparticles in the size range 5-12 nm has been investigated. In this size interval, the decahedral morphology has been identified as the most favourable structure at or above room temperature, while particle surface roughening becomes evident above 600{sup 0}C. An icosahedral transition has also been identified at low temperature in particles under 9 nm in diameter. These experimental results are consistent with recently published temperature dependent equilibrium phase maps for gold nanoparticles.

  20. Evaluation of riser 14 temperature response

    International Nuclear Information System (INIS)

    OGDEN, D.M.


    The initial sluicing activities of Project WRSS resulted in a two month increase in temperatures as measured by the Riser 14 thermocouple tree of tank 241-C-106. While this increase was anticipated, the maximum temperature was higher than expected. An evaluation was performed to determine if adequate subcooling exists in the waste to continue sluicing activities. It was determined that a minimum of 10 F subcooling exists in the waste and that the higher Riser 14 temperatures were the result of higher than assumed waste saturation temperature

  1. Eye surface temperature detects stress response in budgerigars (Melopsittacus undulatus). (United States)

    Ikkatai, Yuko; Watanabe, Shigeru


    Previous studies have suggested that stressors not only increase body core temperature but also body surface temperature in many animals. However, it remains unclear whether surface temperature could be used as an alternative to directly measure body core temperature, particularly in birds. We investigated whether surface temperature is perceived as a stress response in budgerigars. Budgerigars have been used as popular animal models to investigate various neural mechanisms such as visual perception, vocal learning, and imitation. Developing a new technique to understand the basic physiological mechanism would help neuroscience researchers. First, we found that cloacal temperature correlated with eye surface temperature. Second, eye surface temperature increased after handling stress. Our findings suggest that eye surface temperature is closely related to cloacal temperature and that the stress response can be measured by eye surface temperature in budgerigars.

  2. Entropy Generation of Desalination Powered by Variable Temperature Waste Heat

    Directory of Open Access Journals (Sweden)

    David M. Warsinger


    Full Text Available Powering desalination by waste heat is often proposed to mitigate energy consumption and environmental impact; however, thorough technology comparisons are lacking in the literature. This work numerically models the efficiency of six representative desalination technologies powered by waste heat at 50, 70, 90, and 120 °C, where applicable. Entropy generation and Second Law efficiency analysis are applied for the systems and their components. The technologies considered are thermal desalination by multistage flash (MSF, multiple effect distillation (MED, multistage vacuum membrane distillation (MSVMD, humidification-dehumidification (HDH, and organic Rankine cycles (ORCs paired with mechanical technologies of reverse osmosis (RO and mechanical vapor compression (MVC. The most efficient technology was RO, followed by MED. Performances among MSF, MSVMD, and MVC were similar but the relative performance varied with waste heat temperature or system size. Entropy generation in thermal technologies increases at lower waste heat temperatures largely in the feed or brine portions of the various heat exchangers used. This occurs largely because lower temperatures reduce recovery, increasing the relative flow rates of feed and brine. However, HDH (without extractions had the reverse trend, only being competitive at lower temperatures. For the mechanical technologies, the energy efficiency only varies with temperature because of the significant losses from the ORC.

  3. Seasonal temperature variability and emergency hospital admissions for respiratory diseases: a population-based cohort study. (United States)

    Sun, Shengzhi; Laden, Francine; Hart, Jaime E; Qiu, Hong; Wang, Yan; Wong, Chit Ming; Lee, Ruby Siu-Yin; Tian, Linwei


    Climate change increases global mean temperature and changes short-term (eg, diurnal) and long-term (eg, intraseasonal) temperature variability. Numerous studies have shown that mean temperature and short-term temperature variability are both associated with increased respiratory morbidity or mortality. However, data on the impact of long-term temperature variability are sparse. We aimed to assess the association of intraseasonal temperature variability with respiratory disease hospitalisations among elders. We ascertained the first occurrence of emergency hospital admissions for respiratory diseases in a prospective Chinese elderly cohort of 66 820 older people (≥65 years) with 10-13 years of follow-up. We used an ordinary kriging method based on 22 weather monitoring stations in Hong Kong to spatially interpolate daily ambient temperature for each participant's residential address. Seasonal temperature variability was defined as the SD of daily mean summer (June-August) or winter (December-February) temperatures. We applied Cox proportional hazards regression with time-varying exposure of seasonal temperature variability to respiratory admissions. During the follow-up time, we ascertained 12 689 cases of incident respiratory diseases, of which 6672 were pneumonia and 3075 were COPD. The HRs per 1°C increase in wintertime temperature variability were 1.20 (95% CI 1.08 to 1.32), 1.15 (1.01 to 1.31) and 1.41 (1.15 to 1.71) for total respiratory diseases, pneumonia and COPD, respectively. The associations were not statistically significant for summertime temperature variability. Wintertime temperature variability was associated with higher risk of incident respiratory diseases. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  4. Variable capacity utilization, ambient temperature shocks and generation asset valuation

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, Chung-Li; Dmitriev, Alexandre [Australian School of Business, University of New South Wales, Sydney NSW 2052 (Australia); Zhu, Wei [Optim Energy, 225 E. John Carpenter Freeway, Irving, TX 75062 (United States)


    This paper discusses generation asset valuation in a framework where capital utilization decisions are endogenous. We use real options approach for valuation of natural gas fueled turbines. Capital utilization choices that we explore include turning on/off the unit, operating the unit at increased firing temperatures (overfiring), and conducting preventive maintenance. Overfiring provides capacity enhancement which comes at the expense of reduced maintenance interval and increased costs of part replacement. We consider the costs and benefits of overfiring in attempt to maximize the asset value by optimally exercising the overfire option. In addition to stochastic processes governing prices, we incorporate an exogenous productivity shock: ambient temperature. We consider how variation in ambient temperature affects the asset value through its effect on gas turbine's productivity. (author)

  5. Comparing daily temperature averaging methods: the role of surface and atmosphere variables in determining spatial and seasonal variability (United States)

    Bernhardt, Jase; Carleton, Andrew M.


    The two main methods for determining the average daily near-surface air temperature, twice-daily averaging (i.e., [Tmax+Tmin]/2) and hourly averaging (i.e., the average of 24 hourly temperature measurements), typically show differences associated with the asymmetry of the daily temperature curve. To quantify the relative influence of several land surface and atmosphere variables on the two temperature averaging methods, we correlate data for 215 weather stations across the Contiguous United States (CONUS) for the period 1981-2010 with the differences between the two temperature-averaging methods. The variables are land use-land cover (LULC) type, soil moisture, snow cover, cloud cover, atmospheric moisture (i.e., specific humidity, dew point temperature), and precipitation. Multiple linear regression models explain the spatial and monthly variations in the difference between the two temperature-averaging methods. We find statistically significant correlations between both the land surface and atmosphere variables studied with the difference between temperature-averaging methods, especially for the extreme (i.e., summer, winter) seasons (adjusted R2 > 0.50). Models considering stations with certain LULC types, particularly forest and developed land, have adjusted R2 values > 0.70, indicating that both surface and atmosphere variables control the daily temperature curve and its asymmetry. This study improves our understanding of the role of surface and near-surface conditions in modifying thermal climates of the CONUS for a wide range of environments, and their likely importance as anthropogenic forcings—notably LULC changes and greenhouse gas emissions—continues.

  6. Characterizing Temperature Variability and Associated Large Scale Meteorological Patterns Across South America (United States)

    Detzer, J.; Loikith, P. C.; Mechoso, C. R.; Barkhordarian, A.; Lee, H.


    South America's climate varies considerably owing to its large geographic range and diverse topographical features. Spanning the tropics to the mid-latitudes and from high peaks to tropical rainforest, the continent experiences an array of climate and weather patterns. Due to this considerable spatial extent, assessing temperature variability at the continent scale is particularly challenging. It is well documented in the literature that temperatures have been increasing across portions of South America in recent decades, and while there have been many studies that have focused on precipitation variability and change, temperature has received less scientific attention. Therefore, a more thorough understanding of the drivers of temperature variability is critical for interpreting future change. First, k-means cluster analysis is used to identify four primary modes of temperature variability across the continent, stratified by season. Next, composites of large scale meteorological patterns (LSMPs) are calculated for months assigned to each cluster. Initial results suggest that LSMPs, defined using meteorological variables such as sea level pressure (SLP), geopotential height, and wind, are able to identify synoptic scale mechanisms important for driving temperature variability at the monthly scale. Some LSMPs indicate a relationship with known recurrent modes of climate variability. For example, composites of geopotential height suggest that the Southern Annular Mode is an important, but not necessarily dominant, component of temperature variability over southern South America. This work will be extended to assess the drivers of temperature extremes across South America.

  7. Diurnal variability of upper ocean temperature and heat budget in ...

    Indian Academy of Sciences (India)

    Time-series data on upper-ocean temperature, Vessel-Mounted Acoustic Doppler Current Profiler (VM-ADCP) measured currents and surface meteorological parameters have been obtained for the first time in the southern Bay of Bengal at 7° N, 10° N, and 13° N locations along 87° E during October - November, 1998 ...

  8. Temporal changes and variability in temperature series over Peninsular Malaysia (United States)

    Suhaila, Jamaludin


    With the current concern over climate change, the descriptions on how temperature series changed over time are very useful. Annual mean temperature has been analyzed for several stations over Peninsular Malaysia. Non-parametric statistical techniques such as Mann-Kendall test and Theil-Sen slope estimation are used primarily for assessing the significance and detection of trends, while a nonparametric Pettitt's test and sequential Mann-Kendall test are adopted to detect any abrupt climate change. Statistically significance increasing trends for annual mean temperature are detected for almost all studied stations with the magnitude of significant trend varied from 0.02°C to 0.05°C per year. The results shows that climate over Peninsular Malaysia is getting warmer than before. In addition, the results of the abrupt changes in temperature using Pettitt's and sequential Mann-Kendall test reveal the beginning of trends which can be related to El Nino episodes that occur in Malaysia. In general, the analysis results can help local stakeholders and water managers to understand the risks and vulnerabilities related to climate change in terms of mean events in the region.

  9. Lithology and temperature: How key mantle variables control rift volcanism (United States)

    Shorttle, O.; Hoggard, M.; Matthews, S.; Maclennan, J.


    Continental rifting is often associated with extensive magmatic activity, emplacing millions of cubic kilometres of basalt and triggering environmental change. The lasting geological record of this volcanic catastrophism are the large igneous provinces found at the margins of many continents and abrupt extinctions in the fossil record, most strikingly that found at the Permo-Triassic boundary. Rather than being considered purely a passive plate tectonic phenomenon, these episodes are frequently explained by the involvement of mantle plumes, upwellings of mantle rock made buoyant by their high temperatures. However, there has been debate over the relative role of the mantle's temperature and composition in generating the large volumes of magma involved in rift and intra-plate volcanism, and even when the mantle is inferred to be hot, this has been variously attributed to mantle plumes or continental insulation effects. To help resolve these uncertainties we have combined geochemical, geophysical and modelling results in a two stage approach: Firstly, we have investigated how mantle composition and temperature contribute to melting beneath Iceland, the present day manifestation of the mantle plume implicated in the 54Ma break up of the North Atlantic. By considering both the igneous crustal production on Iceland and the chemistry of its basalts we have been able to place stringent constraints on the viable temperature and lithology of the Icelandic mantle. Although a >100°C excess temperature is required to generate Iceland's thick igneous crust, geochemistry also indicates that pyroxenite comprises 10% of its source. Therefore, the dynamics of rifting on Iceland are modulated both by thermal and compositional mantle anomalies. Secondly, we have performed a global assessment of the mantle's post break-up thermal history to determine the amplitude and longevity of continental insulation in driving excess volcanism. Using seismically constrained igneous crustal

  10. Modeling of concrete response at high temperature

    International Nuclear Information System (INIS)

    Pfeiffer, P.; Marchertas, A.


    A rate-type creep law is implemented into the computer code TEMP-STRESS for high temperature concrete analysis. The disposition of temperature, pore pressure and moisture for the particular structure in question is provided as input for the thermo-mechanical code. The loss of moisture from concrete also induces material shrinkage which is accounted for in the analytical model. Examples are given to illustrate the numerical results

  11. Pressure and pressure derivative analysis for injection tests with variable temperature without type-curve matching

    International Nuclear Information System (INIS)

    Escobar, Freddy Humberto; Martinez, Javier Andres; Montealegre Matilde


    The analysis of injection tests under nonisothermic conditions is important for the accurate estimation of the reservoir permeability and the well's skin factor; since previously an isothermical system was assumed without taking into account a moving temperature front which expands with time plus the consequent changes in both viscosity and mobility between the cold and the hot zone of the reservoir which leads to unreliable estimation of the reservoir and well parameters. To construct the solution an analytical approach presented by Boughrara and Peres (2007) was used. That solution was initially introduced for the calculation of the injection pressure in an isothermic system. It was later modified by Boughrara and Reynolds (2007) to consider a system with variable temperature in vertical wells. In this work, the pressure response was obtained by numerical solution of the anisothermical model using the Gauss Quadrature method to solve the integrals, and assuming that both injection and reservoir temperatures were kept constant during the injection process and the water saturation is uniform throughout the reservoir. For interpretation purposes, a technique based upon the unique features of the pressure and pressure derivative curves were used without employing type-curve matching (TDS technique). The formulation was verified by its application to field and synthetic examples. As expected, increasing reservoir temperature causes a decrement in the mobility ratio, then estimation of reservoir permeability is some less accurate from the second radial flow, especially, as the mobility ratio increases

  12. Variable-temperature NMR and conformational analysis of Oenothein B

    International Nuclear Information System (INIS)

    Santos, Suzana C.; Carvalho, Ariadne G.; Fortes, Gilmara A.C.; Ferri, Pedro H.; Oliveira, Anselmo E. de


    Oenothein B is a dimeric hydrolyzable tannin with a wide range of biological activities, such as antitumour, anti-inflammatory and antiviral. Its nuclear magnetic resonance (NMR) at room temperature show duplications and broadening of signals. Experiments of 1D and 2D NMR at lower temperatures were useful for the complete NMR assignments of all hydrogens and carbons. The 3D structure of the most stable conformer was determined for the first time by nuclear Overhauser effect spectroscopy (NOESY) experiment (-20 deg C) and density functional theory (DFT)(B3LYP/6-31G)/ polarizable continuum model (PCM) quantum chemical calculations. The favoured conformation showed a highly compacted geometry and a lack of symmetry, in which the two valoneoyl groups showed distinct conformational parameters and stabilities. (author)

  13. Variable-temperature NMR and conformational analysis of Oenothein B

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Suzana C.; Carvalho, Ariadne G.; Fortes, Gilmara A.C.; Ferri, Pedro H.; Oliveira, Anselmo E. de, [Universidade Federal de Goias (UFGO), Goiania, GO (Brazil). Instituto de Quimica


    Oenothein B is a dimeric hydrolyzable tannin with a wide range of biological activities, such as antitumour, anti-inflammatory and antiviral. Its nuclear magnetic resonance (NMR) at room temperature show duplications and broadening of signals. Experiments of 1D and 2D NMR at lower temperatures were useful for the complete NMR assignments of all hydrogens and carbons. The 3D structure of the most stable conformer was determined for the first time by nuclear Overhauser effect spectroscopy (NOESY) experiment (-20 deg C) and density functional theory (DFT)(B3LYP/6-31G)/ polarizable continuum model (PCM) quantum chemical calculations. The favoured conformation showed a highly compacted geometry and a lack of symmetry, in which the two valoneoyl groups showed distinct conformational parameters and stabilities. (author)

  14. Variable temperature effects on release rates of readily soluble nuclides

    International Nuclear Information System (INIS)

    Kim, C.-L.; Light, W.B.; Lee, W.W.-L.; Chambre, P.L.; Pigford, T.H.


    In this paper we study the effect of temperature on the release rate of readily soluble nuclides, as affected by a time-temperature dependent diffusion coefficient. In this analysis ground water fills the voids in the waste package at t = 0 and one percent of the inventories of cesium and iodine are immediately dissolved into the void water. Mass transfer resistance of partly failed container and cladding is conservatively neglected. The nuclides move through the void space into the surrounding rock under a concentration gradient. We use an analytic solution to compute the nuclide concentration in the gap or void, and the mass flux rate into the porous rock. 8 refs., 4 figs

  15. Study Progress of Physiological Responses in High Temperature Environment (United States)

    Li, K.; Zheng, G. Z.; Bu, W. T.; Wang, Y. J.; Lu, Y. Z.


    Certain workers are exposed to high temperatures for a long time. Heat stress will result in a series of physiological responses, and cause adverse effects on the health and safety of workers. This paper summarizes the physiological changes of cardiovascular system, core temperature, skin temperature, water-electrolyte metabolism, alimentary system, neuroendocrine system, reaction time and thermal fatigue in high temperature environments. It can provide a theoretical guidance for labor safety in high temperature environment.

  16. Sensitivity of soil respiration to variability in soil moisture and temperature in a humid tropical forest (United States)

    Tana Wood; M. Detto; W.L. Silver


    Precipitation and temperature are important drivers of soil respiration. The role of moisture and temperature are generally explored at seasonal or inter-annual timescales; however, significant variability also occurs on hourly to daily time-scales. We used small (1.54 m2), throughfall exclusion shelters to evaluate the role soil moisture and temperature as temporal...

  17. The Response of Ice Sheets to Climate Variability (United States)

    Snow, K.; Goldberg, D. N.; Holland, P. R.; Jordan, J. R.; Arthern, R. J.; Jenkins, A.


    West Antarctic Ice Sheet loss is a significant contributor to sea level rise. While the ice loss is thought to be triggered by fluctuations in oceanic heat at the ice shelf bases, ice sheet response to ocean variability remains poorly understood. Using a synchronously coupled ice-ocean model permitting grounding line migration, this study evaluates the response of an ice sheet to periodic variations in ocean forcing. Resulting oscillations in grounded ice volume amplitude is shown to grow as a nonlinear function of ocean forcing period. This implies that slower oscillations in climatic forcing are disproportionately important to ice sheets. The ice shelf residence time offers a critical time scale, above which the ice response amplitude is a linear function of ocean forcing period and below which it is quadratic. These results highlight the sensitivity of West Antarctic ice streams to perturbations in heat fluxes occurring at decadal time scales.

  18. Variability in Glycemic Control with Temperature Transitions during Therapeutic Hypothermia

    Directory of Open Access Journals (Sweden)

    Krystal K. Haase


    Full Text Available Purpose. Patients treated with therapeutic hypothermia (TH and continuous insulin may be at increased risk of hyperglycemia or hypoglycemia, particularly during temperature transitions. This study aimed to evaluate frequency of glucose excursions during each phase of TH and to characterize glycemic control patterns in relation to survival. Methods. Patients admitted to a tertiary care hospital for circulatory arrest and treated with both therapeutic hypothermia and protocol-based continuous insulin between January 2010 and June 2013 were included. Glucose measures, insulin, and temperatures were collected through 24 hours after rewarming. Results. 24 of 26 patients experienced glycemic excursions. Hyperglycemic excursions were more frequent during initiation versus remaining phases (36.3%, 4.3%, 2.5%, and 4.0%, p=0.002. Hypoglycemia occurred most often during rewarming (0%, 7.7%, 23.1%, and 3.8%, p=0.02. Patients who experienced hypoglycemia had higher insulin doses prior to rewarming (16.2 versus 2.1 units/hr, p=0.03. Glucose variation was highest during hypothermia and trended higher in nonsurvivors compared to survivors (13.38 versus 9.16, p=0.09. Frequency of excursions was also higher in nonsurvivors (32.3% versus 19.8%, p=0.045. Conclusions. Glycemic excursions are common and occur more often in nonsurvivors. Excursions differ by phase but risk of hypoglycemia is increased during rewarming.

  19. Tack Measurements of Prepreg Tape at Variable Temperature and Humidity (United States)

    Wohl, Christopher; Palmieri, Frank L.; Forghani, Alireza; Hickmott, Curtis; Bedayat, Houman; Coxon, Brian; Poursartip, Anoush; Grimsley, Brian


    NASA’s Advanced Composites Project has established the goal of achieving a 30 percent reduction in the timeline for certification of primary composite structures for application on commercial aircraft. Prepreg tack is one of several critical parameters affecting composite manufacturing by automated fiber placement (AFP). Tack plays a central role in the prevention of wrinkles and puckers that can occur during AFP, thus knowledge of tack variation arising from a myriad of manufacturing and environmental conditions is imperative for the prediction of defects during AFP. A full design of experiments was performed to experimentally characterize tack on 0.25-inch slit-tape tow IM7/8552-1 prepreg using probe tack testing. Several process parameters (contact force, contact time, retraction speed, and probe diameter) as well as environmental parameters (temperature and humidity) were varied such that the entire parameter space could be efficiently evaluated. Mid-point experimental conditions (i.e., parameters not at either extrema) were included to enable prediction of curvature in relationships and repeat measurements were performed to characterize experimental error. Collectively, these experiments enable determination of primary dependencies as well as multi-parameter relationships. Slit-tape tow samples were mounted to the bottom plate of a rheometer parallel plate fixture using a jig to prevent modification of the active area to be interrogated with the top plate, a polished stainless steel probe, during tack testing. The probe surface was slowly brought into contact with the pre-preg surface until a pre-determined normal force was achieved (2-30 newtons). After a specified dwell time (0.02-10 seconds), during which the probe substrate interaction was maintained under displacement control, the probe was retracted from the surface (0.1-50 millimeters per second). Initial results indicated a clear dependence of tack strength on several parameters, with a particularly

  20. Synergy effects of fluoxetine and variability in temperature lead to proportionally greater fitness costs in Daphnia: A multigenerational test. (United States)

    Barbosa, Miguel; Inocentes, Núrya; Soares, Amadeu M V M; Oliveira, Miguel


    Increased variability in water temperature is predicted to impose disproportionally greater fitness costs than mean increase in temperature. Additionally, water contaminants are currently a major source of human-induced stress likely to produce fitness costs. Global change models forecast an increase in these two human-induced stressors. Yet, in spite the growing interest in understanding how organisms respond to global change, the joint fitness effects of water pollution and increased variability in temperature remain unclear. Here, using a multigenerational design, we test the hypothesis that exposure to high concentrations of fluoxetine, a human medicine commonly found in freshwater systems, causes increased lifetime fitness costs, when associated with increased variability in temperature. Although fluoxetine and variability in temperature elicited some fitness cost when tested alone, when both stressors acted together the costs were disproportionally greater. The combined effect of fluoxetine and variability in temperature led to a reduction of 37% in lifetime reproductive success and a 17.9% decrease in population growth rate. Interestingly, fluoxetine and variability in temperature had no effect on the probability of survival. Freshwater systems are among the most imperilled ecosystems, often exposed to multiple human-induced stressors. Our results indicate that organisms face greater fitness risk when exposed to multiple stressors at the same time than when each stress acts alone. Our study highlights the importance of using a multi-generational approach to fully understand individual environmental tolerance and its responses to a global change scenario in aquatic systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Temperature responses of exercizing dogs to infusion of electrolytes (United States)

    Greenleaf, J. E.; Kozlowski, S.; Nazar, K.; Kaciuba-Uscilko, H.; Brzezinska, Z.


    The effect of infusions with solutions of various ionic and osmotic composition on exercise temperature responses was studied in dogs who do not regulate their temperature by sweating. The results suggest an association between plasma Na+ and Ca++ level within the normal physiological range and the control of body temperature during exercise.

  2. Amplification and dampening of soil respiration by changes in temperature variability

    Directory of Open Access Journals (Sweden)

    C. A. Sierra


    Full Text Available Accelerated release of carbon from soils is one of the most important feedbacks related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature variability. Anthropogenic activities are likely to modify both the average state and the variability of the climatic system; therefore, the effects of future warming on decomposition should not only focus on trends in the average temperature, but also variability expressed as a change of the probability distribution of temperature. Using analytical and numerical analyses we tested common relationships between temperature and respiration and found that the variability of temperature plays an important role determining respiration rates of soil organic matter. Changes in temperature variability, without changes in the average temperature, can affect the amount of carbon released through respiration over the long-term. Furthermore, simultaneous changes in the average and variance of temperature can either amplify or dampen the release of carbon through soil respiration as climate regimes change. These effects depend on the degree of convexity of the relationship between temperature and respiration and the magnitude of the change in temperature variance. A potential consequence of this effect of variability would be higher respiration in regions where both the mean and variance of temperature are expected to increase, such as in some low latitude regions; and lower amounts of respiration where the average temperature is expected to increase and the variance to decrease, such as in northern high latitudes.

  3. Amplification and dampening of soil respiration by changes in temperature variability (United States)

    Sierra, C.A.; Harmon, M.E.; Thomann, E.; Perakis, S.S.; Loescher, H.W.


    Accelerated release of carbon from soils is one of the most important feed backs related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature vari-ability. Anthropogenic activities are likely to modify both the average state and the variability of the climatic system; therefore, the effects of future warming on decomposition should not only focus on trends in the average temperature, but also variability expressed as a change of the probability distribution of temperature.Using analytical and numerical analyses we tested common relationships between temperature and respiration and found that the variability of temperature plays an important role determining respiration rates of soil organic matter. Changes in temperature variability, without changes in the average temperature, can affect the amount of carbon released through respiration over the long term. Furthermore, simultaneous changes in the average and variance of temperature can either amplify or dampen there release of carbon through soil respiration as climate regimes change. The effects depend on the degree of convexity of the relationship between temperature and respiration and the magnitude of the change in temperature variance. A potential consequence of this effect of variability would be higher respiration in regions where both the mean and variance of temperature are expected to increase, such as in some low latitude regions; and lower amounts of respiration where the average temperature is expected to increase and the variance to decrease, such as in northern high latitudes.

  4. Estimation of road profile variability from measured vehicle responses (United States)

    Fauriat, W.; Mattrand, C.; Gayton, N.; Beakou, A.; Cembrzynski, T.


    When assessing the statistical variability of fatigue loads acting throughout the life of a vehicle, the question of the variability of road roughness naturally arises, as both quantities are strongly related. For car manufacturers, gathering information on the environment in which vehicles evolve is a long and costly but necessary process to adapt their products to durability requirements. In the present paper, a data processing algorithm is proposed in order to estimate the road profiles covered by a given vehicle, from the dynamic responses measured on this vehicle. The algorithm based on Kalman filtering theory aims at solving a so-called inverse problem, in a stochastic framework. It is validated using experimental data obtained from simulations and real measurements. The proposed method is subsequently applied to extract valuable statistical information on road roughness from an existing load characterisation campaign carried out by Renault within one of its markets.

  5. Multimodel Surface Temperature Responses to Removal of U.S. Sulfur Dioxide Emissions (United States)

    Conley, A. J.; Westervelt, D. M.; Lamarque, J.-F.; Fiore, A. M.; Shindell, D.; Correa, G.; Faluvegi, G.; Horowitz, L. W.


    Three Earth System models are used to derive surface temperature responses to removal of U.S. anthropogenic SO2 emissions. Using multicentury perturbation runs with and without U.S. anthropogenic SO2 emissions, the local and remote surface temperature changes are estimated. In spite of a temperature drift in the control and large internal variability, 200 year simulations yield statistically significant regional surface temperature responses to the removal of U.S. SO2 emissions. Both local and remote surface temperature changes occur in all models, and the patterns of changes are similar between models for northern hemisphere land regions. We find a global average temperature sensitivity to U.S. SO2 emissions of 0.0055 K per Tg(SO2) per year with a range of (0.0036, 0.0078). We examine global and regional responses in SO4 burdens, aerosol optical depths (AODs), and effective radiative forcing (ERF). While changes in AOD and ERF are concentrated near the source region (United States), the temperature response is spread over the northern hemisphere with amplification of the temperature increase toward the Arctic. In all models, we find a significant response of dust concentrations, which affects the AOD but has no obvious effect on surface temperature. Temperature sensitivity to the ERF of U.S. SO2 emissions is found to differ from the models' sensitivity to radiative forcing of doubled CO2.

  6. Variable reluctance displacement transducer temperature compensated to 6500F

    International Nuclear Information System (INIS)


    In pressurized water reactor tests, compact instruments for accurate measurement of small displacements in a 650 0 F environment are often required. In the case of blowdown tests such as the Loss of Fluid Test (LOFT) or Semiscale computer code development tests, not only is the initial environment water at 650 0 F and 2200 psi but it undergoes a severe transient due to depressurization. Since the LOFT and Semiscale tests are run just for the purpose of obtaining data during the depressurization, instruments used to obtain the data must not give false outputs induced by the change in environment. A LOFT rho v 2 probe and a Semiscale drag disk are described. Each utilizes a variable reluctance transducer (VRT) for indication of the drag-disk location and a torsion bar for drag-disk restoring force. The VRT, in addition to being thermally gain and null offset stable, is fabricated from materials known to be resistant to large nuclear radiation levels and has successfully passed a fast neutron radiation test of 2.7 x 10 17 nvt without failure

  7. Ecological response of Cedrus atlantica to climate variability in the Massif of Guetiane (Algeria

    Directory of Open Access Journals (Sweden)

    Said Slimani


    Full Text Available Aim of the study: The study analyzes the long-term response of Atlas cedar, Cedrus atlantica (Manneti, to climate variability. Area of study: Atlas cedar forest of Guetiane (Batna, Algeria.Material and methods: The dendrochronological approach was adopted. An Atlas cedar tree-ring chronology was established from twenty trees. The response of the species to climate variability was assessed through the pointer years (PYs, the common climate signal among the individual chronologies, expressed by the first component (PC1, the mean sensitivity (msx, and response function and correlations analysis involving the tree-ring index and climate data (monthly mean temperature and total precipitation.Results: The highest growth variability was registered from the second half of the 20th century. The lower than the mean PYs, the PC1, and the msx increased markedly during the studied period. Dramatic increases in the PC1 and msx were detected at the end of the 1970s, reflecting a shift towards drier conditions enhancing an increasing trend towards more synchronous response of trees to climate conditions. The response function and correlations analysis showed that tree growth was mainly influenced by precipitation variability.Research highlights: Our findings provide baseline knowledge concerning the ecological response of Atlas cedar to climate variability in in its southern distribution limit, where a high level of tree mortality has been observed during recent decades, coinciding with the driest period Algeria has ever experienced. This information is vital to support ongoing ecosystem management efforts in the region. Keywords: Atlas cedar; annual growth variability; dieback; dendrochronology. 

  8. Ecosystem responses to recent oceanographic variability in high-latitude Northern Hemisphere ecosystems (United States)

    Mueter, Franz J.; Broms, Cecilie; Drinkwater, Kenneth F.; Friedland, Kevin D.; Hare, Jonathan A.; Hunt, George L., Jr.; Melle, Webjørn; Taylor, Maureen


    As part of the international MENU collaboration, we compared and contrasted ecosystem responses to climate-forced oceanographic variability across several high latitude regions of the North Pacific (Eastern Bering Sea (EBS) and Gulf of Alaska (GOA)) and North Atlantic Oceans (Gulf of Maine/Georges Bank (GOM/GB) and the Norwegian/Barents Seas (NOR/BAR)). Differences in the nitrate content of deep source waters and incoming solar radiation largely explain differences in average primary productivity among these ecosystems. We compared trends in productivity and abundance at various trophic levels and their relationships with sea-surface temperature. Annual net primary production generally increases with annual mean sea-surface temperature between systems and within the EBS, BAR, and GOM/GB. Zooplankton biomass appears to be controlled by both top-down (predation by fish) and bottom-up forcing (advection, SST) in the BAR and NOR regions. In contrast, zooplankton in the GOM/GB region showed no evidence of top-down forcing but appeared to control production of major fish populations through bottom-up processes that are independent of temperature variability. Recruitment of several fish stocks is significantly and positively correlated with temperature in the EBS and BAR, but cod and pollock recruitment in the EBS has been negatively correlated with temperature since the 1977 shift to generally warmer conditions. In each of the ecosystems, fish species showed a general poleward movement in response to warming. In addition, the distribution of groundfish in the EBS has shown a more complex, non-linear response to warming resulting from internal community dynamics. Responses to recent warming differ across systems and appear to be more direct and more pronounced in the higher latitude systems where food webs and trophic interactions are simpler and where both zooplankton and fish species are often limited by cold temperatures.

  9. Hafnium(IV) complexation with oxalate at variable temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Friend, Mitchell T.; Wall, Nathalie A. [Washington State Univ., Pullmanm, WA (United States). Dept. of Chemistry


    Appropriate management of fission products in the reprocessing of spent nuclear fuel (SNF) is crucial in developing advanced reprocessing schemes. The addition of aqueous phase complexing agents can prevent the co-extraction of these fission products. A solvent extraction technique was used to study the complexation of Hf(IV) - an analog to fission product Zr(IV) - with oxalate at 15, 25, and 35 C in 1 M HClO{sub 4} utilizing a {sup 175+181}Hf radiotracer. The mechanism of the solvent extraction system of 10{sup -5} M Hf(IV) in 1 M HClO{sub 4} to thenoyltrifluoroacetone (TTA) in toluene demonstrated a 4{sup th}-power dependence in both TTA and H{sup +}, with Hf(TTA){sub 4} the only extractable species. The equilibrium constant for the extraction of Hf(TTA){sub 4} was determined to be log K{sub ex}=7.67±0.07 (25±1 C, 1 M HClO{sub 4}). The addition of oxalate to the aqueous phase decreased the distribution ratio, indicating aqueous Hf(IV)-oxalate complex formation. Polynomial fits to the distribution data identified the formation of Hf(ox){sup 2+} and Hf(ox){sub 2(aq)} and their stability constants were measured at 15, 25, and 35 C in 1 M HClO{sub 4}. van't Hoff analysis was used to calculate Δ{sub r}G, Δ{sub r}H, and Δ{sub r}S for these species. Stability constants were observed to increase at higher temperature, an indication that Hf(IV)-oxalate complexation is endothermic and driven by entropy.

  10. Subseasonal Reversal of East Asian Surface Temperature Variability in Winter 2014/15 (United States)

    Xu, Xinping; Li, Fei; He, Shengping; Wang, Huijun


    Although there has been a considerable amount of research conducted on the East Asian winter-mean climate, subseasonal surface air temperature (SAT) variability reversals in the early and late winter remain poorly understood. In this study, we focused on the recent winter of 2014/15, in which warmer anomalies dominated in January and February but colder conditions prevailed in December. Moreover, Arctic sea-ice cover (ASIC) in September-October 2014 was lower than normal, and warmer sea surface temperature (SST) anomalies occurred in the Niño4 region in winter, together with a positive Pacific Decadal Oscillation (PDO|+) phase. Using observational data and CMIP5 historical simulations, we investigated the PDO|+ phase modulation upon the winter warm Niño4 phase (autumn ASIC reduction) influence on the subseasonal SAT variability of East Asian winter. The results show that, under a PDO|+ phase modulation, warm Niño4 SST anomalies are associated with a subseasonal delay of tropical surface heating and subsequent Hadley cell and Ferrel cell intensification in January-February, linking the tropical and midlatitude regions. Consistently, the East Asian jet stream (EAJS) is significantly decelerated in January-February and hence promotes the warm anomalies over East Asia. Under the PDO|+ phase, the decrease in ASIC is related to cold SST anomalies in the western North Pacific, which increase the meridional temperature gradient and generate an accelerated and westward-shifted EAJS in December. The westward extension of the EAJS is responsible for the eastward-propagating Rossby waves triggered by declining ASIC and thereby favors the connection between ASIC and cold conditions over East Asia.

  11. Fuel temperature prediction using a variable bypass gap size in the prismatic VHTR

    International Nuclear Information System (INIS)

    Lee, Sung Nam; Tak, Nam-il; Kim, Min Hwan


    Highlights: • The bypass flow of the prismatic very high temperature reactor is analyzed. • The bypass gap sizes are calculated considering the effect of the neutron fluences and thermal expansion. • The fuel hot spot temperature and temperature profiles are calculated using the variable gap size. • The BOC, MOC and EOC condition at the cycle 07 and 14 are applied. - Abstract: The temperature gradient and hot spot temperatures were calculated in the prismatic very high temperature reactor as a function of the variable bypass gap size. Many previous studies have predicted the temperature of the reactor core based on a fixed bypass gap size. The graphite matrix of the assemblies in the reactor core undergoes a dimensional change during the operation due to thermal expansion and neutron fluence. The expansion and shrinkage of the bypass gaps change the coolant flow fractions into the coolant channels, the control rod holes, and the bypass gaps. Therefore, the temperature of the assemblies may differ compared to those for the fixed bypass gap case. The temperature gradient and the hot spot temperatures are important for the design of reactor structures to ensure their safety and efficiency. In the present study, the temperature variation of the PMR200 is studied at the beginning (BOC), middle (MOC), and end (EOC) of cycles 07 and 14. CORONA code which has been developed in KAERI is applied to solve the thermal-hydraulics of the reactor core of the PMR200. CORONA solves a fluid region using a one-dimensional formulation and a solid region using a three-dimensional formulation to enhance the computational speed and still obtain a reasonable accuracy. The maximum temperatures in the fuel assemblies using the variable bypass gaps did not differ much from the corresponding temperatures using the fixed bypass gaps. However, the maximum temperatures in the reflector assemblies using the variable bypass gaps differ significantly from the corresponding temperatures

  12. Response of wheat restricted-tillering and vigorous growth traits to variables of climate change. (United States)

    Dias de Oliveira, Eduardo A; Siddique, Kadambot H M; Bramley, Helen; Stefanova, Katia; Palta, Jairo A


    The response of wheat to the variables of climate change includes elevated CO2, high temperature, and drought which vary according to the levels of each variable and genotype. Independently, elevated CO2, high temperature, and terminal drought affect wheat biomass and grain yield, but the interactive effects of these three variables are not well known. The aim of this study was to determine the effects of elevated CO2 when combined with high temperature and terminal drought on the high-yielding traits of restricted-tillering and vigorous growth. It was hypothesized that elevated CO2 alone, rather than combined with high temperature, ameliorates the effects of terminal drought on wheat biomass and grain yield. It was also hypothesized that wheat genotypes with more sink capacity (e.g. high-tillering capacity and leaf area) have more grain yield under combined elevated CO2, high temperature, and terminal drought. Two pairs of sister lines with contrasting tillering and vigorous growth were grown in poly-tunnels in a four-factor completely randomized split-plot design with elevated CO2 (700 µL L(-1)), high day time temperature (3 °C above ambient), and drought (induced from anthesis) in all combinations to test whether elevated CO2 ameliorates the effects of high temperature and terminal drought on biomass accumulation and grain yield. For biomass and grain yield, only main effects for climate change variables were significant. Elevated CO2 significantly increased grain yield by 24-35% in all four lines and terminal drought significantly reduced grain yield by 16-17% in all four lines, while high temperature (3 °C above the ambient) had no significant effect. A trade-off between yield components limited grain yield in lines with greater sink capacity (free-tillering lines). This response suggests that any positive response to predicted changes in climate will not overcome the limitations imposed by the trade-off in yield components. © 2014 Commonwealth of

  13. Temporal and Spatial Variabilities of Japan Sea Surface Temperature and Atmospheric Forcings

    National Research Council Canada - National Science Library

    Chu, Peter C; Chen, Yuchun; Lu, Shihua


    ...) and surface air temperature (SAT) data during 1982-1994 and the National Center for Atmospheric Research surface wind stress curl data during 1982-1989 to investigate the Japan Sea SST temporal and spatial variabilities...

  14. Sea surface temperature variability over North Indian Ocean - A study of two contrasting monsoon seasons

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Sathyendranath, S.; Viswambharan, N.K.; Rao, L.V.G.

    Using the satellite derived sea surface temperature (SST) data for 1979 (bad monsoon) and 1983 (good monsoon), the SST variability for two contrasting monsoon seasons is studied. The study indicates that large negative anomalies off the Somali...

  15. Influence of climate on emergency department visits for syncope: role of air temperature variability.

    Directory of Open Access Journals (Sweden)

    Andrea Galli

    Full Text Available BACKGROUND: Syncope is a clinical event characterized by a transient loss of consciousness, estimated to affect 6.2/1000 person-years, resulting in remarkable health care and social costs. Human pathophysiology suggests that heat may promote syncope during standing. We tested the hypothesis that the increase of air temperatures from January to July would be accompanied by an increased rate of syncope resulting in a higher frequency of Emergency Department (ED visits. We also evaluated the role of maximal temperature variability in affecting ED visits for syncope. METHODOLOGY/PRINCIPAL FINDINGS: We included 770 of 2775 consecutive subjects who were seen for syncope at four EDs between January and July 2004. This period was subdivided into three epochs of similar length: 23 January-31 March, 1 April-31 May and 1 June-31 July. Spectral techniques were used to analyze oscillatory components of day by day maximal temperature and syncope variability and assess their linear relationship. There was no correlation between daily maximum temperatures and number of syncope. ED visits for syncope were lower in June and July when maximal temperature variability declined although the maximal temperatures themselves were higher. Frequency analysis of day by day maximal temperature variability showed a major non-random fluctuation characterized by a ∼23-day period and two minor oscillations with ∼3- and ∼7-day periods. This latter oscillation was correlated with a similar ∼7-day fluctuation in ED visits for syncope. CONCLUSIONS/SIGNIFICANCE: We conclude that ED visits for syncope were not predicted by daily maximal temperature but were associated with increased temperature variability. A ∼7-day rhythm characterized both maximal temperatures and ED visits for syncope variability suggesting that climate changes may have a significant effect on the mode of syncope occurrence.


    Directory of Open Access Journals (Sweden)

    M. MATEI


    Full Text Available The main objective of the present paper is to analyze the temporal and spatial variability of air-temperature in Romania, by using mean air-temperature values provided by the ECA&D project ( These data sets will be filtered by means of the EOF (Empirical Orthogonal Function analysis, which describes various modes of space variability and time coefficient series (PC series. The EOF analysis will also be used to identify the main way of action of the European climate variability mechanism, by using multiple variables in grid points, provided by the National Centre of Atmospheric Research (NCAR, USA. The variables considered here are: sea level pressure (SLP, geopotential height at 500 mb (H500 and air temperature at 850 mb (T850, for the summer and winter seasons. The linear trends and shift points of considered variables are then assessed by means of the Mann-Kendall and Pettitt non-parametric tests. By interpreting the results, we can infer that there is causal relationship between the large-scale analyzed parameters and temperature variability in Romania. These results are consistent with those presented by Busuioc et al., 2010, where the main variation trends of the principal European variables are shown.

  17. Variable-temperature Microwave Impedance Microscope with Light Stimulation for Research on Photo-induced Phase Transitions (United States)


    SECURITY CLASSIFICATION OF: The DURIP program "Variable-temperature Microwave Impedance Microscope with Light Stimulation for Research on Photo... Stimulation for Research on Photo- induced Phase Transitions The views, opinions and/or findings contained in this report are those of the author(s) and should...reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions

  18. The Benefit of Variable-Speed Turbine Operation for Low Temperature Thermal Energy Power Recovery


    Brasz, Joost J.


    This paper analyzes, given the large variation in turbine discharge pressure with changing ambient temperatures, whether variable-speed radial-inflow turbine operation has a similar benefit for Organic Rankine Cycle (ORC) power recovery systems as variable-speed centrifugal compression has for chiller applications. The benefit of variable-speed centrifugal compression over fixed-speed operation is a reduction in annual electricity consumption of almost 40 %. Air-conditioning systems are by ne...

  19. A Hydrological Response Analysis Considering Climatic Variability: Case Study of Hunza Catchment

    Directory of Open Access Journals (Sweden)

    A. N. Laghari


    Full Text Available The hydrological response of mountainous catchments particularly dependent on melting runoff is very vulnerable to climatic variability. This study is an attempt to assess hydrological response towards climatic variability of the Hunza catchment located in the mountainous chain of greater Hindu Kush-Himalaya (HKH region. The hydrological response is analyzed through changes in snowmelt, ice melt and total runoff simulated through the application of the hydrological modeling system PREVAH under hypothetically developed climate change scenarios. The developed scenarios are based on changes in precipitation (Prp and temperature (Tmp and their combination. Under all the warmer scenarios, the increase in temperature systematically decreases the mean annual snow melt and increases significantly glacier melt volume. Temperature changes from 1°C to 4°C produce a large increase in spring and summer runoff, while no major variation was observed in the winter and autumn runoff. The maximum seasonal changes recorded under the Tmp+4°C, Prp+10% scenario.

  20. A variable-temperature nanostencil compatible with a low-temperature scanning tunneling microscope/atomic force microscope

    International Nuclear Information System (INIS)

    Steurer, Wolfram; Gross, Leo; Schlittler, Reto R.; Meyer, Gerhard


    We describe a nanostencil lithography tool capable of operating at variable temperatures down to 30 K. The setup is compatible with a combined low-temperature scanning tunneling microscope/atomic force microscope located within the same ultra-high-vacuum apparatus. The lateral movement capability of the mask allows the patterning of complex structures. To demonstrate operational functionality of the tool and estimate temperature drift and blurring, we fabricated LiF and NaCl nanostructures on Cu(111) at 77 K

  1. A variable-temperature nanostencil compatible with a low-temperature scanning tunneling microscope/atomic force microscope

    Energy Technology Data Exchange (ETDEWEB)

    Steurer, Wolfram, E-mail:; Gross, Leo; Schlittler, Reto R.; Meyer, Gerhard [IBM Research-Zurich, 8803 Rüschlikon (Switzerland)


    We describe a nanostencil lithography tool capable of operating at variable temperatures down to 30 K. The setup is compatible with a combined low-temperature scanning tunneling microscope/atomic force microscope located within the same ultra-high-vacuum apparatus. The lateral movement capability of the mask allows the patterning of complex structures. To demonstrate operational functionality of the tool and estimate temperature drift and blurring, we fabricated LiF and NaCl nanostructures on Cu(111) at 77 K.

  2. A variable-temperature nanostencil compatible with a low-temperature scanning tunneling microscope/atomic force microscope. (United States)

    Steurer, Wolfram; Gross, Leo; Schlittler, Reto R; Meyer, Gerhard


    We describe a nanostencil lithography tool capable of operating at variable temperatures down to 30 K. The setup is compatible with a combined low-temperature scanning tunneling microscope/atomic force microscope located within the same ultra-high-vacuum apparatus. The lateral movement capability of the mask allows the patterning of complex structures. To demonstrate operational functionality of the tool and estimate temperature drift and blurring, we fabricated LiF and NaCl nanostructures on Cu(111) at 77 K.

  3. Separating heat stress from moisture stress: analyzing yield response to high temperature in irrigated maize (United States)

    Carter, Elizabeth K.; Melkonian, Jeff; Riha, Susan J.; Shaw, Stephen B.


    Several recent studies have indicated that high air temperatures are limiting maize (Zea mays L.) yields in the US Corn Belt and project significant yield losses with expected increases in growing season temperatures. Further work has suggested that high air temperatures are indicative of high evaporative demand, and that decreases in maize yields which correlate to high temperatures and vapor pressure deficits (VPD) likely reflect underlying soil moisture limitations. It remains unclear whether direct high temperature impacts on yields, independent of moisture stress, can be observed under current temperature regimes. Given that projected high temperature and moisture may not co-vary the same way as they have historically, quantitative analyzes of direct temperature impacts are critical for accurate yield projections and targeted mitigation strategies under shifting temperature regimes. To evaluate yield response to above optimum temperatures independent of soil moisture stress, we analyzed climate impacts on irrigated maize yields obtained from the National Corn Growers Association (NCGA) corn yield contests for Nebraska, Kansas and Missouri. In irrigated maize, we found no evidence of a direct negative impact on yield by daytime air temperature, calculated canopy temperature, or VPD when analyzed seasonally. Solar radiation was the primary yield-limiting climate variable. Our analyses suggested that elevated night temperature impacted yield by increasing rates of phenological development. High temperatures during grain-fill significantly interacted with yields, but this effect was often beneficial and included evidence of acquired thermo-tolerance. Furthermore, genetics and management—information uniquely available in the NCGA contest data—explained more yield variability than climate, and significantly modified crop response to climate. Thermo-acclimation, improved genetics and changes to management practices have the potential to partially or completely

  4. Thermal characterization of European ant communities along thermal gradients and its implications for community resilience to temperature variability

    Directory of Open Access Journals (Sweden)

    Xavier eArnan


    Full Text Available Ecologists are increasingly concerned about how climate change will affect biodiversity yet have mostly addressed the issue at the species level. Here, we present a novel framework that accounts for the full range and complementarity of thermal responses present in a community; it may help reveal how biological communities will respond to climatic (i.e., thermal variability. First, we characterized the thermal niches of 147 ant species from 342 communities found along broad temperature gradients in western Europe. Within each community, species’ mean thermal breadth and the difference among species’ thermal optima (thermal complementarity were considered to define community thermal niche breadth—our proxy for community thermal resilience. The greater the range of thermal responses and their complementarity within a community, the greater the likelihood that the community could cope with novel conditions. Second, we used simulations to calculate how robust community thermal resilience was to random species extinctions. Community resilience was considered to be robust when random species extinctions largely failed to constrict initial community thermal breadth. Our results indicate that community thermal resilience was negatively and positively correlated with mean temperature and temperature seasonality, respectively. The pattern was reversed for robustness. While species richness did not directly affect community resilience to thermal variability, it did have a strong indirect effect because it determined community resilience robustness. Consequently, communities in warm, aseasonal regions are the most vulnerable to temperature variability, despite their greater number of species and resultant greater resilience robustness.

  5. Patterns of intraspecific variability in the response to caloric restriction (United States)

    Gribble, Kristin E.; Kaido, Oksana; Jarvis, George; Mark Welch, David B.


    Caloric restriction (CR) is cited as the most robust means of increasing lifespan across a range of taxa, yet there is a high degree of variability in the response to CR, both within and between species. To examine the intraspecific evolutionary conservation of lifespan extension by CR, we tested the effects of chronic caloric restriction (CCR) at multiple food levels and of intermittent fasting (IF) in twelve isolates from the Brachionus plicatilis species complex of monogonont rotifers. While CCR generally increased or did not change lifespan and total fecundity, IF caused increased, unchanged, or decreased lifespan, depending upon the isolate, and decreased total fecundity in all but one isolate. Lifespan under ad libitum (AL) feeding varied among isolates and predicted the lifespan response to CR: longer-lived isolates under AL were less likely to have a significant increase in lifespan under CCR and were more likely to have a significantly shortened lifespan under IF. Lifespan under AL conditions and the response to CR were not correlated with hydroperiodicity of native habitat or with time in culture. Lack of trade-off between lifespan and fecundity under CCR, and differences in lifespan and fecundity under CCR and IF, even when average food intake was similar, suggest that longevity changes are not always directly determined by energy intake and that CCR and IF regimens extend lifespan through diverse genetic mechanisms. PMID:24384399

  6. Sensitivity of summer stream temperatures to climate variability in the Pacific Northwest (United States)

    Charles Luce; Brian Staab; Marc Kramer; Seth Wenger; Dan Isaak; Callie McConnell


    Estimating the thermal response of streams to a warming climate is important for prioritizing native fish conservation efforts. While there are plentiful estimates of air temperature responses to climate change, the sensitivity of streams, particularly small headwater streams, to warming temperatures is less well understood. A substantial body of literature correlates...

  7. Evidence for large temperature fluctuations in quasar accretion disks from spectral variability

    Energy Technology Data Exchange (ETDEWEB)

    Ruan, John J.; Anderson, Scott F.; Agol, Eric [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Dexter, Jason, E-mail: [Departments of Physics and Astronomy, University of California, Berkeley, CA 94720 (United States)


    The well-known bluer-when-brighter trend observed in quasar variability is a signature of the complex processes in the accretion disk and can be a probe of the quasar variability mechanism. Using a sample of 604 variable quasars with repeat spectra in the Sloan Digital Sky Survey-I/II (SDSS), we construct difference spectra to investigate the physical causes of this bluer-when-brighter trend. The continuum of our composite difference spectrum is well fit by a power law, with a spectral index in excellent agreement with previous results. We measure the spectral variability relative to the underlying spectra of the quasars, which is independent of any extinction, and compare to model predictions. We show that our SDSS spectral variability results cannot be produced by global accretion rate fluctuations in a thin disk alone. However, we find that a simple model of an inhomogeneous disk with localized temperature fluctuations will produce power-law spectral variability over optical wavelengths. We show that the inhomogeneous disk will provide good fits to our observed spectral variability if the disk has large temperature fluctuations in many independently varying zones, in excellent agreement with independent constraints from quasar microlensing disk sizes, their strong UV spectral continuum, and single-band variability amplitudes. Our results provide an independent constraint on quasar variability models and add to the mounting evidence that quasar accretion disks have large localized temperature fluctuations.

  8. Amplification and dampening of soil respiration by changes in temperature variability (United States)

    C.A. Sierra; M.E. Harmon; E.A. Thomann; S.S. Perakis; H.W. Loescher


    Accelerated release of carbon from soils is one of the most important feedbacks related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature variability. Anthropogenic...

  9. Kiloampere, Variable-Temperature, Critical-Current Measurements of High-Field Superconductors. (United States)

    Goodrich, L F; Cheggour, N; Stauffer, T C; Filla, B J; Lu, X F


    We review variable-temperature, transport critical-current (I c) measurements made on commercial superconductors over a range of critical currents from less than 0.1 A to about 1 kA. We have developed and used a number of systems to make these measurements over the last 15 years. Two exemplary variable-temperature systems with coil sample geometries will be described: a probe that is only variable-temperature and a probe that is variable-temperature and variable-strain. The most significant challenge for these measurements is temperature stability, since large amounts of heat can be generated by the flow of high current through the resistive sample fixture. Therefore, a significant portion of this review is focused on the reduction of temperature errors to less than ±0.05 K in such measurements. A key feature of our system is a pre-regulator that converts a flow of liquid helium to gas and heats the gas to a temperature close to the target sample temperature. The pre-regulator is not in close proximity to the sample and it is controlled independently of the sample temperature. This allows us to independently control the total cooling power, and thereby fine tune the sample cooling power at any sample temperature. The same general temperature-control philosophy is used in all of our variable-temperature systems, but the addition of another variable, such as strain, forces compromises in design and results in some differences in operation and protocol. These aspects are analyzed to assess the extent to which the protocols for our systems might be generalized to other systems at other laboratories. Our approach to variable-temperature measurements is also placed in the general context of measurement-system design, and the perceived advantages and disadvantages of design choices are presented. To verify the accuracy of the variable-temperature measurements, we compared critical-current values obtained on a specimen immersed in liquid helium ("liquid" or I c liq) at 5

  10. Variable-temperature sample system for ion implantation at -192 to +5000C

    International Nuclear Information System (INIS)

    Fuller, C.T.


    A variable-temperature sample system based on exchange-gas coupling was developed for ion-implantation use. The sample temperature can be controlled from -192 0 C to +500 0 C with rapid cooling. The system also has provisions for focusing and alignment of the ion beam, electron suppression, temperature monitoring, sample current measuring, and cryo-shielding. Design considerations and operating characteristics are discussed. 5 figures

  11. Heat transfer effects on flow past an exponentially accelerated vertical plate with variable temperature

    Directory of Open Access Journals (Sweden)

    Muthucumaraswamy R.


    Full Text Available An exact solution to the problem of flow past an exponentially accelerated infinite vertical plate with variable temperature is analyzed. The temperature of the plate is raised linearly with time t. The dimensionless governing equations are solved using Laplace-transform technique. The velocity and temperature profiles are studied for different physical parameters like thermal Grashof number Gr, time and an accelerating parameter a. It is observed that the velocity increases with increasing values of a or Gr.

  12. Contact parameter identification for vibrational response variability prediction

    DEFF Research Database (Denmark)

    Creixell Mediante, Ester; Brunskog, Jonas; Jensen, Jakob Søndergaard


    industry, where the vibrational behavior of the structures within the hearing frequency range is critical for the performance of the devices. A procedure to localize the most probable contact areas and determine the most sensitive contact points with respect to variations in the modes of vibration......Variability in the dynamic response of assembled structures can arise due to variations in the contact conditions between the parts that conform them. Contact conditions are difficult to model accurately due to randomness in physical properties such as contact surface, load distribution...... or geometric details. Those properties can vary for a given structure due to the assembly and disassembly process, and also across nominally equal items that are produced in series. This work focuses on modeling the contact between small light-weight plastic pieces such as those used in the hearing aid...

  13. Physiological and biochemical responses to low temperature stress ...

    African Journals Online (AJOL)

    Cuttings of three hybrid clones of P. ussuriensis × P. deltoides were exposed to different low temperatures (cold and freezing) for 24 h, or consecutive low temperatures (5°C, 0 to 120 h), to determine physiological and biochemical responses to cold stress in these woody plants. Soluble sugar and protein contents increased ...

  14. Surface-temperature trends and variability in the low-latitude North Atlantic since 1552

    KAUST Repository

    Saenger, Casey; Cohen, Anne L.; Oppo, Delia W.; Halley, Robert B.; Carilli, Jessica E.


    Sea surface temperature variability in the North Atlantic Ocean recorded since about 1850 has been ascribed to a natural multidecadal oscillation superimposed on a background warming trend1-6. It has been suggested that the multidecadal variability may be a persistent feature6-8, raising the possibility that the associated climate impacts may be predictable7,8. owever, our understanding of the multidecadal ocean variability before the instrumental record is based on interpretations of high-latitude terrestrial proxy records. Here we present an absolutely dated and annually resolved record of sea surface temperature from the Bahamas, based on a 440-year time series of coral growth rates. The reconstruction indicates that temperatures were as warm as today from about 1552 to 1570, then cooled by about 1° C from 1650 to 1730 before warming until the present. Our estimates of background variability suggest that much of the warming since 1900 was driven by anthropogenic forcing. Interdecadal variability with a period of 15-25 years is superimposed on most of the record, but multidecadal variability becomes significant only after 1730. We conclude that the multidecadal variability in sea surface temperatures in the low-latitude western Atlantic Ocean may not be persistent, potentially making accurate decadal climate forecasts more difficult to achieve. © 2009 Macmillan Publishers Limited. All rights reserved.

  15. Surface-temperature trends and variability in the low-latitude North Atlantic since 1552

    KAUST Repository

    Saenger, Casey


    Sea surface temperature variability in the North Atlantic Ocean recorded since about 1850 has been ascribed to a natural multidecadal oscillation superimposed on a background warming trend1-6. It has been suggested that the multidecadal variability may be a persistent feature6-8, raising the possibility that the associated climate impacts may be predictable7,8. owever, our understanding of the multidecadal ocean variability before the instrumental record is based on interpretations of high-latitude terrestrial proxy records. Here we present an absolutely dated and annually resolved record of sea surface temperature from the Bahamas, based on a 440-year time series of coral growth rates. The reconstruction indicates that temperatures were as warm as today from about 1552 to 1570, then cooled by about 1° C from 1650 to 1730 before warming until the present. Our estimates of background variability suggest that much of the warming since 1900 was driven by anthropogenic forcing. Interdecadal variability with a period of 15-25 years is superimposed on most of the record, but multidecadal variability becomes significant only after 1730. We conclude that the multidecadal variability in sea surface temperatures in the low-latitude western Atlantic Ocean may not be persistent, potentially making accurate decadal climate forecasts more difficult to achieve. © 2009 Macmillan Publishers Limited. All rights reserved.

  16. Temperature Response in Hardened Concrete Subjected to Tropical Rainforest Environment

    Directory of Open Access Journals (Sweden)

    E. I. Egba


    Full Text Available The objective of this paper is to characterize concrete micro-environment temperature response to the natural climate of the tropical rainforest. The peculiar warmth, high humidity, and low pressure nature of the tropical rainforest necessitated the present study. Temperature probes were inserted into concrete specimens subjected to the sheltered and unsheltered environment to measure the micro-environment temperature of the concrete, and study the hysteresis characteristics in relation to the climate temperature. Some mathematical relationships for forecasting the internal temperature of concrete in the tropical rainforest environment were proposed and tested. The proposed relationships were found reliable. It was observed that the micro-environment temperature was lower at the crest, and higher at the trough than the climate environment temperature with a temperature difference of 1-3 oC. Also, temperature response in concrete for the unsheltered micro-environment was 1.85 times faster than the response in the sheltered micro-environment. The findings of the study may be used to assist the durability assessment of concrete.

  17. Response of ENSO amplitude to global warming in CESM large ensemble: uncertainty due to internal variability (United States)

    Zheng, Xiao-Tong; Hui, Chang; Yeh, Sang-Wook


    El Niño-Southern Oscillation (ENSO) is the dominant mode of variability in the coupled ocean-atmospheric system. Future projections of ENSO change under global warming are highly uncertain among models. In this study, the effect of internal variability on ENSO amplitude change in future climate projections is investigated based on a 40-member ensemble from the Community Earth System Model Large Ensemble (CESM-LE) project. A large uncertainty is identified among ensemble members due to internal variability. The inter-member diversity is associated with a zonal dipole pattern of sea surface temperature (SST) change in the mean along the equator, which is similar to the second empirical orthogonal function (EOF) mode of tropical Pacific decadal variability (TPDV) in the unforced control simulation. The uncertainty in CESM-LE is comparable in magnitude to that among models of the Coupled Model Intercomparison Project phase 5 (CMIP5), suggesting the contribution of internal variability to the intermodel uncertainty in ENSO amplitude change. However, the causations between changes in ENSO amplitude and the mean state are distinct between CESM-LE and CMIP5 ensemble. The CESM-LE results indicate that a large ensemble of 15 members is needed to separate the relative contributions to ENSO amplitude change over the twenty-first century between forced response and internal variability.

  18. Coastal upwelling seasonality and variability of temperature and chlorophyll in a small coastal embayment (United States)

    Walter, Ryan K.; Armenta, Kevin J.; Shearer, Brandon; Robbins, Ian; Steinbeck, John


    While the seasonality of wind-driven coastal upwelling in eastern boundary upwelling systems has long been established, many studies describe two distinct seasons (upwelling and non-upwelling), a generalized framework that does not capture details relevant to marine ecosystems. In this contribution, we present a more detailed description of the annual cycle and upwelling seasonality for an understudied location along the central California coast. Using both the mean monthly upwelling favorable wind stress and the monthly standard deviation, we define the following seasons (contiguous months) and a transitional period (non-contiguous months): "Winter Storms" season (Dec-Jan-Feb), "Upwelling Transition" period (Mar and Jun), "Peak Upwelling" season (Apr-May), "Upwelling Relaxation" season (Jul-Aug-Sep), and "Winter Transition" season (Oct-Nov). In order to describe the oceanic response to this upwelling wind seasonality, we take advantage of nearly a decade of full water-column measurements of temperature and chlorophyll made using an automated profiling system at the end of the California Polytechnic State University Pier in San Luis Obispo Bay, a small ( 2 km wide near study site) and shallow ( 10 m average bay depth) coastal embayment. Variability and average-year patterns are described inside the bay during the various upwelling seasons. Moreover, the role of the local coastline orientation and topography on bay dynamics is also assessed using long-term measurements collected outside of the bay. The formation of a seasonally variable upwelling shadow system and potential nearshore retention zone is discussed. The observations presented provide a framework on which to study interannual changes to the average-year seasonal cycle, assess the contribution of higher-frequency features to nearshore variability, and better predict dynamically and ecologically important events.

  19. Response variability to glucose facilitation of cognitive enhancement. (United States)

    Owen, Lauren; Scholey, Andrew; Finnegan, Yvonne; Sünram-Lea, Sandra I


    Glucose facilitation of cognitive function has been widely reported in previous studies (including our own). However, several studies have also failed to detect glucose facilitation. There is sparsity of research examining the factors that modify the effect of glucose on cognition. The aims of the present study were to (1) demonstrate the previously observed enhancement of cognition through glucose administration and (2) investigate some of the factors that may exert moderating roles on the behavioural response to glucose, including glucose regulation, body composition (BC) and hypothalamic–pituitary–adrenal axis response. A total of twenty-four participants took part in a double-blind, placebo-controlled, randomised, repeated-measures study, which examined the effect of 25 and 60 g glucose compared with placebo on cognitive function. At 1 week before the study commencement, all participants underwent an oral glucose tolerance test. Glucose facilitated performance on tasks of numeric and spatial working memory, verbal declarative memory and speed of recognition. Moderating variables were examined using several indices of glucoregulation and BC. Poorer glucoregulation predicted improved immediate word recall accuracy following the administration of 25 g glucose compared with placebo. Those with better glucoregulation showed performance decrements on word recall accuracy following the administration of 25 g glucose compared with placebo. These findings are in line with accumulating evidence that glucose load may preferentially enhance cognition in those with poorer glucoregulation. Furthermore, the finding that individuals with better glucoregulation may suffer impaired performance following a glucose load is novel and requires further substantiation.

  20. When is affect variability bad for health? The association between affect variability and immune response to the influenza vaccination. (United States)

    Jenkins, Brooke N; Hunter, John F; Cross, Marie P; Acevedo, Amanda M; Pressman, Sarah D


    This study addresses methodological and theoretical questions about the association between affect and physical health. Specifically, we examine the role of affect variability and its interaction with mean levels of affect to predict antibody (Ab) levels in response to an influenza vaccination. Participants (N=83) received the vaccination and completed daily diary measures of affect four times a day for 13days. At one and four months post-vaccination, blood was collected from the participants to assess Ab levels. Findings indicate that affect variability and its interaction with mean levels of affect predict an individual's immune response. Those high in mean positive affect (PA) who had more PA variability were more likely to have a lower Ab response in comparison to those who had high mean PA and less PA variability. Although it did not interact with mean negative affect (NA), NA variability on its own was associated with Ab response, whereby those with less NA variability mounted a more robust immune response. Affect variability is related to immune response to an influenza vaccination and, in some cases, interacts with mean levels of affect. These oscillations in affective experiences are critical to consider in order to unpack the intricacies of how affect influences health. These findings suggest that future researchers should consider the important role of affect variability on physical health-relevant outcomes as well as examine the moderating effect of mean affect levels. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Sea Surface Temperature and Ocean Color Variability in the South China Sea (United States)

    Conaty, A. P.


    The South China Sea is a marginal sea in the Southeast Asian region whose surface circulation is driven by monsoons and whose surface currents have complex seasonal patterns. Its rich natural resources and strategic location have made its small islands areas of political dispute among the neighboring nations. This study aims to show the seasonal and interannual variability of sea surface temperature and ocean color in South China Sea. It makes use of NOAA's Advanced Very High Resolution Radiometer (AVHRR) satellite data sets on sea surface temperature for the period 1981-2000 and NASA's Nimbus-7 Coastal Zone Color Scanner (CZCS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite data sets on pigment concentration (ocean color) for the period 1981-1996 and 1997-2000, respectively. Transect lines were drawn along several potential hotspot areas to show the variability in sea surface temperature and pigment concentration through time. In-situ data on sea surface temperature along South China Sea were likewise plotted to see the variability with time. Higher seasonal variability in sea surface temperature was seen at higher latitudes. Interannual variability was within 1-3 Kelvin. In most areas, pigment concentration was higher during northern hemisphere winter and autumn, after the monsoon rains, with a maximum of 30 milligrams per cubic meter.

  2. Consequences of Part Temperature Variability in Electron Beam Melting of Ti-6Al-4V (United States)

    Fisher, Brian A.; Mireles, Jorge; Ridwan, Shakerur; Wicker, Ryan B.; Beuth, Jack


    To facilitate adoption of Ti-6Al-4V (Ti64) parts produced via additive manufacturing (AM), the ability to ensure part quality is critical. Measuring temperatures is an important component of part quality monitoring in all direct metal AM processes. In this work, surface temperatures were monitored using a custom infrared camera system attached to an Arcam electron beam melting (EBM®) machine. These temperatures were analyzed to understand their possible effect on solidification microstructure based on solidification cooling rates extracted from finite element simulations. Complicated thermal histories were seen during part builds, and temperature changes occurring during typical Ti64 builds may be large enough to affect solidification microstructure. There is, however, enough time between fusion of individual layers for spatial temperature variations (i.e., hot spots) to dissipate. This means that an effective thermal control strategy for EBM® can be based on average measured surface temperatures, ignoring temperature variability.

  3. Variable temperature 127I MAS NMR of β-AgI

    International Nuclear Information System (INIS)

    Wagner, G.W.


    Variable temperature 127 I MAS NMR of β-AgI powder, measured from 123 to 413 K is sensitive to Ag + diffusion through the iodine lattice. In low temperature spectra, the iodine ions appear to be in nearly static environments in agreement with the low temperature crystal structure. However, at higher temperatures, substantial broadening of the central transition linewidth is consistent with the presence of two types of Ag + diffusion with activation energies of 0.17 and 0.0080 eV. (author). 15 refs.; 5 figs.; 1 tab

  4. Change features and regional distribution of temperature trend and variability joint mode in mainland China (United States)

    Chen, Xi; Li, Ning; Zhang, Zhengtao; Feng, Jieling; Wang, Ye


    Adaption for temperature should be suitable to local conditions for regional differences in temperature change features. This paper proposed to utilize nine temperature modes that joint the trend (increasing/decreasing/unchanged) with variability (intensifying/weakening/unchanged) to investigate features of temperature change in mainland China. Monthly temperature data over the period 1960-2013 were obtained from 522 national basic and reference meteorological stations. Here, temperature trend (TT) was reflected by the trend of mean annual temperature (MAT) and the uptrend (downtrend) of inter-monthly sliding standard deviation (SSD) series with a sliding length of 29 years (348 months) was used for representing the intensification (weakening) of temperature variability (TV). The Mann-Kendall method and the least squares method were applied to assess the significance and quantify the magnitude of trend in MAT and SSD time series, respectively. The results show that there is a consistent warming trend throughout the country except for only three stations in which a cooling trend is identified. Moreover, the overall increasing rate in the north of 35° N is the highest, over 0.4 °C/decade for most stations. TV is weakened for almost 98% of the stations, indicating the low instability of temperature at a national scale. Finally, temperature mode (TM), for more than 90% of the stations, is the combination of an increasing TT with a weakened TV (mode 8). So, it is more important for people to adapt to the increasing temperature in these regions. Compared to using annual temperature data to calculate SSD, monthly data can accurately reflect the inter-monthly change of temperature and reserve more initial characteristics of temperature.

  5. Complex response of white pines to past environmental variability increases understanding of future vulnerability.

    Directory of Open Access Journals (Sweden)

    Virginia Iglesias

    Full Text Available Ecological niche models predict plant responses to climate change by circumscribing species distributions within a multivariate environmental framework. Most projections based on modern bioclimatic correlations imply that high-elevation species are likely to be extirpated from their current ranges as a result of rising growing-season temperatures in the coming decades. Paleoecological data spanning the last 15,000 years from the Greater Yellowstone region describe the response of vegetation to past climate variability and suggest that white pines, a taxon of special concern in the region, have been surprisingly resilient to high summer temperature and fire activity in the past. Moreover, the fossil record suggests that winter conditions and biotic interactions have been critical limiting variables for high-elevation conifers in the past and will likely be so in the future. This long-term perspective offers insights on species responses to a broader range of climate and associated ecosystem changes than can be observed at present and should be part of resource management and conservation planning for the future.

  6. Variable temperature ion trap studies of CH4+ + H2, HD and D2: negative temperature dependence and significant isotope effect

    International Nuclear Information System (INIS)

    Asvany, O.; Savic, I.; Schlemmer, S.; Gerlich, D.


    Reactions of methane cations, CH 4 + , with H 2 , HD and D 2 have been studied in a variable temperature 22-pole ion trap from room temperature down to 15 K. The formation of CH 5 + in collisions with H 2 is slow at 300 K, but it becomes faster by at least one order of magnitude when the temperature is lowered to 15 K. This behavior is tentatively explained with a longer complex lifetime at low temperatures. However, since tunneling is most probably not responsible for product formation, other dynamical or statistical restrictions must be responsible for the negative temperature dependence. In collisions of CH 4 + with HD, the CH 5 + product ion (68% at 15 K) prevails over CH 4 D + (32%). Reaction of CH 4 + with D 2 is found to be much slower than with H 2 or HD. The rate coefficient for converting CH 4 + into CH 3 D + by H-D exchange has been determined to be smaller than 10 -12 cm 3 /s, indicating that scrambling in the CH 6 + complex is very unlikely

  7. Variable temperature ion trap studies of CH{sub 4}{sup +} + H{sub 2}, HD and D{sub 2}: negative temperature dependence and significant isotope effect

    Energy Technology Data Exchange (ETDEWEB)

    Asvany, O.; Savic, I.; Schlemmer, S.; Gerlich, D


    Reactions of methane cations, CH{sub 4}{sup +}, with H{sub 2}, HD and D{sub 2} have been studied in a variable temperature 22-pole ion trap from room temperature down to 15 K. The formation of CH{sub 5}{sup +} in collisions with H{sub 2} is slow at 300 K, but it becomes faster by at least one order of magnitude when the temperature is lowered to 15 K. This behavior is tentatively explained with a longer complex lifetime at low temperatures. However, since tunneling is most probably not responsible for product formation, other dynamical or statistical restrictions must be responsible for the negative temperature dependence. In collisions of CH{sub 4}{sup +} with HD, the CH{sub 5}{sup +} product ion (68% at 15 K) prevails over CH{sub 4}D{sup +} (32%). Reaction of CH{sub 4}{sup +} with D{sub 2} is found to be much slower than with H{sub 2} or HD. The rate coefficient for converting CH{sub 4}{sup +} into CH{sub 3}D{sup +} by H-D exchange has been determined to be smaller than 10{sup -12} cm{sup 3}/s, indicating that scrambling in the CH{sub 6}{sup +} complex is very unlikely.

  8. Linking global climate and temperature variability to widespread amphibian declines putatively caused by disease. (United States)

    Rohr, Jason R; Raffel, Thomas R


    The role of global climate change in the decline of biodiversity and the emergence of infectious diseases remains controversial, and the effect of climatic variability, in particular, has largely been ignored. For instance, it was recently revealed that the proposed link between climate change and widespread amphibian declines, putatively caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), was tenuous because it was based on a temporally confounded correlation. Here we provide temporally unconfounded evidence that global El Niño climatic events drive widespread amphibian losses in genus Atelopus via increased regional temperature variability, which can reduce amphibian defenses against pathogens. Of 26 climate variables tested, only factors associated with temperature variability could account for the spatiotemporal patterns of declines thought to be associated with Bd. Climatic predictors of declines became significant only after controlling for a pattern consistent with epidemic spread (by temporally detrending the data). This presumed spread accounted for 59% of the temporal variation in amphibian losses, whereas El Niño accounted for 59% of the remaining variation. Hence, we could account for 83% of the variation in declines with these two variables alone. Given that global climate change seems to increase temperature variability, extreme climatic events, and the strength of Central Pacific El Niño episodes, climate change might exacerbate worldwide enigmatic declines of amphibians, presumably by increasing susceptibility to disease. These results suggest that changes to temperature variability associated with climate change might be as significant to biodiversity losses and disease emergence as changes to mean temperature.


    Audenaert, J; Vangansbeke, D; Verhoeven, R; De Clercq, P; Tirry, L; Gobin, B


    Predatory mites like Phytoseiulus persimilis Athias-Henriot, Neoseiulus californicus McGregor and N. fallacis (Garman) (Acari: Phytoseiidae) are essential in sustainable control strategies of the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) in warm greenhouse cultures to complement imited available pesticides and to tackle emerging resistance. However, in response to high energy prices, greenhouse plant breeders have recently changed their greenhouse steering strategies, allowing more variation in temperature and humidity. The impact of these variations on biological control agents is poorly understood. Therefore, we constructed functional response models to demonstrate the impact of realistic climate variations on predation efficiency. First, two temperature regimes were compared at constant humidity (70%) and photoperiod (16L:8D): DIF0 (constant temperature) and DIF15 (variable temperature with day-night difference of 15°C). At mean temperatures of 25°C, DIF15 had a negative influence on the predation efficiency of P. persimilis and N. californicus, as compared to DIF0. At low mean temperatures of 15°C, however, DIF15 showed a higher predation efficiency for P. persimilis and N. californicus. For N. fallacis no difference was observed at both 15°C and 25°C. Secondly, two humidity regimes were compared, at a mean temperature of 25°C (DIFO) and constant photoperiod (16L:8D): RHCTE (constant 70% humidity) and RHALT (alternating 40% L:70%D humidity). For P. persimilis and N. fallacis RHCTE resulted in a higher predation efficiency than RHALT, for N. californicus this effect was opposite. This shows that N. californicus is more adapted to dry climates as compared to the other predatory mites. We conclude that variable greenhouse climates clearly affect predation efficiency of P. persimilis, N. californicus and N. fallacis. To obtain optimal control efficiency, the choice of predatory mites (including dose and application frequency

  10. Uncertainty in Indian Ocean Dipole response to global warming: the role of internal variability (United States)

    Hui, Chang; Zheng, Xiao-Tong


    The Indian Ocean Dipole (IOD) is one of the leading modes of interannual sea surface temperature (SST) variability in the tropical Indian Ocean (TIO). The response of IOD to global warming is quite uncertain in climate model projections. In this study, the uncertainty in IOD change under global warming, especially that resulting from internal variability, is investigated based on the community earth system model large ensemble (CESM-LE). For the IOD amplitude change, the inter-member uncertainty in CESM-LE is about 50% of the intermodel uncertainty in the phase 5 of the coupled model intercomparison project (CMIP5) multimodel ensemble, indicating the important role of internal variability in IOD future projection. In CESM-LE, both the ensemble mean and spread in mean SST warming show a zonal positive IOD-like (pIOD-like) pattern in the TIO. This pIOD-like mean warming regulates ocean-atmospheric feedbacks of the interannual IOD mode, and weakens the skewness of the interannual variability. However, as the changes in oceanic and atmospheric feedbacks counteract each other, the inter-member variability in IOD amplitude change is not correlated with that of the mean state change. Instead, the ensemble spread in IOD amplitude change is correlated with that in ENSO amplitude change in CESM-LE, reflecting the close inter-basin relationship between the tropical Pacific and Indian Ocean in this model.

  11. Response of the Amazon rainforest to late Pleistocene climate variability (United States)

    Häggi, Christoph; Chiessi, Cristiano M.; Merkel, Ute; Mulitza, Stefan; Prange, Matthias; Schulz, Michael; Schefuß, Enno


    Variations in Amazonian hydrology and forest cover have major consequences for the global carbon and hydrological cycles as well as for biodiversity. Yet, the climate and vegetation history of the lowland Amazon basin and its effect on biogeography remain debated due to the scarcity of suitable high-resolution paleoclimate records. Here, we use the isotopic composition (δD and δ13C) of plant-waxes from a high-resolution marine sediment core collected offshore the Amazon River to reconstruct the climate and vegetation history of the integrated lowland Amazon basin for the period from 50,000 to 12,800 yr before present. Our results show that δD values from the Last Glacial Maximum were more enriched than those from Marine Isotope Stage (MIS) 3 and the present-day. We interpret this trend to reflect long-term changes in precipitation and atmospheric circulation, with overall drier conditions during the Last Glacial Maximum. Our results thus suggest a dominant glacial forcing of the climate in lowland Amazonia. In addition to previously suggested thermodynamic mechanisms of precipitation change, which are directly related to temperature, we conclude that changes in atmospheric circulation are crucial to explain the temporal evolution of Amazonian rainfall variations, as demonstrated in climate model experiments. Our vegetation reconstruction based on δ13C values shows that the Amazon rainforest was affected by intrusions of savannah or more open vegetation types in its northern sector during Heinrich Stadials, while it was resilient to glacial drying. This suggests that biogeographic patterns in tropical South America were affected by Heinrich Stadials in addition to glacial-interglacial climate variability.

  12. Evaluation of Candidate Linear Variable Displacement Transducers for High Temperature Irradiations in the Advanced Test Reactor

    International Nuclear Information System (INIS)

    Knudson, D.L.; Rempe, J.L.; Daw, J.E.


    The United States (U.S.) Department of Energy (DOE) designated the Advanced Test Reactor (ATR) as a National Scientific User Facility (NSUF) in April 2007 to promote nuclear science and technology in the U.S. Given this designation, the ATR is supporting new users from universities, laboratories, and industry as they conduct basic and applied nuclear research and development to advance the nation's energy security needs. A fundamental component of the ATR NSUF program is to develop in-pile instrumentation capable of providing real-time measurements of key parameters during irradiation experiments. Dimensional change is a key parameter that must be monitored during irradiation of new materials being considered for fuel, cladding, and structures in next generation and existing nuclear reactors. Such materials can experience significant changes during high temperature irradiation. Currently, dimensional changes are determined by repeatedly irradiating a specimen for a defined period of time in the ATR and then removing it from the reactor for evaluation. The time and labor to remove, examine, and return irradiated samples for each measurement makes this approach very expensive. In addition, such techniques provide limited data (i.e., only characterizing the end state when samples are removed from the reactor) and may disturb the phenomena of interest. To address these issues, the Idaho National Laboratory (INL) recently initiated efforts to evaluate candidate linear variable displacement transducers (LVDTs) for use during high temperature irradiation experiments in typical ATR test locations. Two nuclear grade LVDT vendor designs were identified for consideration - a smaller diameter design qualified for temperatures up to 350 C and a larger design with capabilities to 500 C. Initial evaluation efforts include collecting calibration data as a function of temperature, long duration testing of LVDT response while held at high temperature, and the assessment of changes

  13. Investigation on multi-variable decoupled temperature control system for enamelling machine with heated air circulation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yang; Qin, Le; Zou, Shipeng; Long, Shijun [School of Information Engineering, Guangdong University of Technology, Guangzhou, 510006 (China)


    A lots of problems may occur frequently when controlling the temperature of the enamelling machine oven in the real industrial process, such as multi-variable coupled problem. an experimental rig with triple inputs and triple outputs was devised and a simulation modeling was established accordingly in this study,. the temperature control system based on the feedforward compensation algorithm was proposed. Experimental results have shown that the system is of high efficiency, good stability and promising application.

  14. Hypercoagulability in response to elevated body temperature and central hypovolemia

    DEFF Research Database (Denmark)

    Meyer, Martin; Ostrowski, Sisse R; Overgaard, Flemming Anders


    Coagulation abnormalities contribute to poor outcomes in critically ill patients. In trauma patients exposed to a hot environment, a systemic inflammatory response syndrome, elevated body temperature, and reduced central blood volume occur in parallel with changes in hemostasis and endothelial...... damage. The objective of this study was to evaluate whether experimentally elevated body temperature and reduced central blood volume (CBV) per se affects hemostasis and endothelial activation....

  15. Summer U.S. Surface Air Temperature Variability: Controlling Factors and AMIP Simulation Biases (United States)

    Merrifield, A.; Xie, S. P.


    This study documents and investigates biases in simulating summer surface air temperature (SAT) variability over the continental U.S. in the Coupled Model Intercomparison Project (CMIP5) Atmospheric Model Intercomparison Project (AMIP). Empirical orthogonal function (EOF) and multivariate regression analyses are used to assess the relative importance of circulation and the land surface feedback at setting summer SAT over a 30-year period (1979-2008). In observations, regions of high SAT variability are closely associated with midtropospheric highs and subsidence, consistent with adiabatic theory (Meehl and Tebaldi 2004, Lau and Nath 2012). Preliminary analysis shows the majority of the AMIP models feature high SAT variability over the central U.S., displaced south and/or west of observed centers of action (COAs). SAT COAs in models tend to be concomitant with regions of high sensible heat flux variability, suggesting an excessive land surface feedback in these models modulate U.S. summer SAT. Additionally, tropical sea surface temperatures (SSTs) play a role in forcing the leading EOF mode for summer SAT, in concert with internal atmospheric variability. There is evidence that models respond to different SST patterns than observed. Addressing issues with the bulk land surface feedback and the SST-forced component of atmospheric variability may be key to improving model skill in simulating summer SAT variability over the U.S.

  16. Climate variability slows evolutionary responses of Colias butterflies to recent climate change. (United States)

    Kingsolver, Joel G; Buckley, Lauren B


    How does recent climate warming and climate variability alter fitness, phenotypic selection and evolution in natural populations? We combine biophysical, demographic and evolutionary models with recent climate data to address this question for the subalpine and alpine butterfly, Colias meadii, in the southern Rocky Mountains. We focus on predicting patterns of selection and evolution for a key thermoregulatory trait, melanin (solar absorptivity) on the posterior ventral hindwings, which affects patterns of body temperature, flight activity, adult and egg survival, and reproductive success in Colias. Both mean annual summer temperatures and thermal variability within summers have increased during the past 60 years at subalpine and alpine sites. At the subalpine site, predicted directional selection on wing absorptivity has shifted from generally positive (favouring increased wing melanin) to generally negative during the past 60 years, but there is substantial variation among years in the predicted magnitude and direction of selection and the optimal absorptivity. The predicted magnitude of directional selection at the alpine site declined during the past 60 years and varies substantially among years, but selection has generally been positive at this site. Predicted evolutionary responses to mean climate warming at the subalpine site since 1980 is small, because of the variability in selection and asymmetry of the fitness function. At both sites, the predicted effects of adaptive evolution on mean population fitness are much smaller than the fluctuations in mean fitness due to climate variability among years. Our analyses suggest that variation in climate within and among years may strongly limit evolutionary responses of ectotherms to mean climate warming in these habitats. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  17. The relative contributions of tropical Pacific sea surface temperatures and atmospheric internal variability to the recent global warming hiatus (United States)

    Deser, Clara; Guo, Ruixia; Lehner, Flavio


    The recent slowdown in global mean surface temperature (GMST) warming during boreal winter is examined from a regional perspective using 10-member initial-condition ensembles with two global coupled climate models in which observed tropical Pacific sea surface temperature anomalies (TPAC SSTAs) and radiative forcings are specified. Both models show considerable diversity in their surface air temperature (SAT) trend patterns across the members, attesting to the importance of internal variability beyond the tropical Pacific that is superimposed upon the response to TPAC SSTA and radiative forcing. Only one model shows a close relationship between the realism of its simulated GMST trends and SAT trend patterns. In this model, Eurasian cooling plays a dominant role in determining the GMST trend amplitude, just as in nature. In the most realistic member, intrinsic atmospheric dynamics and teleconnections forced by TPAC SSTA cause cooling over Eurasia (and North America), and contribute equally to its GMST trend.

  18. Global land carbon sink response to temperature and precipitation varies with ENSO phase

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yuanyuan; Michalak, Anna M.; Schwalm, Christopher R.; Huntzinger, Deborah N.; Berry, Joseph A.; Ciais, Philippe; Piao, Shilong; Poulter, Benjamin; Fisher, Joshua B.; Cook, Robert B.; Hayes, Daniel; Huang, Maoyi; Ito, Akihiko; Jain, Atul; Lei, Huimin; Lu, Chaoqun; Mao, Jiafu; Parazoo, Nicholas C.; Peng, Shushi; Ricciuto, Daniel M.; Shi, Xiaoying; Tao, Bo; Tian, Hanqin; Wang, Weile; Wei, Yaxing; Yang, Jia


    Climate variability associated with the El Niño-Southern Oscillation (ENSO) and its consequent impacts on land carbon sink interannual variability have been used as a basis for investigating carbon cycle responses to climate variability more broadly, and to inform the sensitivity of the tropical carbon budget to climate change. Past studies have presented opposing views about whether temperature or precipitation is the primary factor driving the response of the land carbon sink to ENSO. Here, we show that the dominant driver varies with ENSO phase. Whereas tropical temperature explains sink dynamics following El Niño conditions (rTG,P=0.59, p<0.01), the post La Niña sink is driven largely by tropical precipitation (rPG,T=-0.46, p=0.04). This finding points to an ENSO-phase-dependent interplay between water availability and temperature in controlling the carbon uptake response to climate variations in tropical ecosystems. We further find that none of a suite of ten contemporary terrestrial biosphere models captures these ENSO-phase-dependent responses, highlighting a key uncertainty in modeling climate impacts on the future of the global land carbon sink.

  19. Changes of interannual NAO variability in response to greenhouse gases forcing

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Buwen; Sutton, Rowan T.; Woollings, Tim [University of Reading, National Centre for Atmospheric Science, Department of Meteorology, Reading (United Kingdom)


    Observations show that there was change in interannual North Atlantic Oscillation (NAO) variability in the mid-1970s. This change was characterized by an eastward shift of the NAO action centres, a poleward shift of zonal wind anomalies and a downstream extension of climate anomalies associated with the NAO. The NAO interannual variability for the period after the mid-1970s has an annular mode structure that penetrates deeply into the stratosphere, indicating a strengthened relationship between the NAO and the Arctic Oscillation (AO) and strengthened stratosphere-troposphere coupling. In this study we have investigated possible causes of these changes in the NAO by carrying out experiments with an atmospheric GCM. The model is forced either by doubling CO{sub 2}, or increasing sea surface temperatures (SST), or both. In the case of SST forcing the SST anomaly is derived from a coupled model simulation forced by increasing CO{sub 2}. Results indicate that SST and CO{sub 2} change both force a poleward and eastward shift in the pattern of interannual NAO variability and the associated poleward shift of zonal wind anomalies, similar to the observations. The effect of SST change can be understood in terms of mean changes in the troposphere. The direct effect of CO{sub 2} change, in contrast, can not be understood in terms of mean changes in the troposphere. However, there is a significant response in the stratosphere, characterized by a strengthened climatological polar vortex with strongly enhanced interannual variability. In this case, the NAO interannual variability has a strong link with the variability over the North Pacific, as in the annular AO pattern, and is also strongly related to the stratospheric vortex, indicating strengthened stratosphere-troposphere coupling. The similarity of changes in many characteristics of NAO interannual variability between the model response to doubling CO{sub 2} and those in observations in the mid-1970s implies that the

  20. European temperature responses to blocking and ridge regional patterns (United States)

    Sousa, Pedro M.; Trigo, Ricardo M.; Barriopedro, David; Soares, Pedro M. M.; Santos, João A.


    Blocking occurrence and its impacts on European temperature have been studied in the last decade. However, most previous studies on blocking impacts have focused on winter only, disregarding its fingerprint in summer and differences with other synoptic patterns that also trigger temperature extremes. In this work, we provide a clear distinction between high-latitude blocking and sub-tropical ridges occurring in three sectors of the Euro-Atlantic region, describing their climatology and consequent impacts on European temperature during both winter and summer. Winter blocks (ridges) are generally associated to colder (warmer) than average conditions over large regions of Europe, in some areas with anomalies larger than 5 °C, particularly for the patterns occurring in the Atlantic and Central European sectors. During summer, there is a more regional response characterized by above average temperature for both blocking and ridge patterns, especially those occurring in continental areas, although negative temperature anomalies persist in southernmost areas during blocking. An objective analysis of the different forcing mechanisms associated to each considered weather regime has been performed, quantifying the importance of the following processes in causing the temperature anomalies: horizontal advection, vertical advection and diabatic heating. While during winter advection processes tend to be more relevant to explain temperature responses, in summer radiative heating under enhanced insolation plays a crucial role for both blocking and ridges. Finally, the changes in the distributions of seasonal temperature and in the frequencies of extreme temperature indices were also examined for specific areas of Europe. Winter blocking and ridge patterns are key drivers in the occurrence of regional cold and warm extreme temperatures, respectively. In summer, they are associated with substantial changes in the frequency of extremely warm days, but with different signatures in

  1. Oxygen isotope variability in snow from western Dronning Maud Land, Antarctica and its relation to temperature

    International Nuclear Information System (INIS)

    Helsen, M.M.; Wal, R.S.W. van de; Broeke, M.R. van den; As, D. van; Reijmer, C.H.; Meijer, H.A.J.


    This paper presents (delta) 18 O records from snow pits from four locations in Dronning Maud Land, Antarctica that contain at least four annual cycles. The aim of the study was to analyse in detail these records as well as the prevailing temperatures during accumulation in order to infer to what extent isotopic composition in this area can be interpreted as temperature information. The original seasonal amplitudes of the isotope records were reconstructed by use of a simple back-diffusion model. Automatic weather station data were used to describe the accumulation history and the near-surface temperatures; the temperatures at the atmospheric level of snow formation were inferred from a regional climate model. The results show that the strongly intermittent nature of the accumulation in this area can result in the exclusion of entire seasons from the isotope records. The temperature records also reveal that the oxygen isotope records in these snow pits are biased towards higher temperatures, since snowfall conditions are associated with higher temperatures. This effect is greatest at low temperatures. A comparison between the seasonal extreme isotopic and temperature values points out that on timescales of seasons to several years, isotopic variability cannot be interpreted with confidence as temperature changes at the accumulation sites

  2. Soil gas radon response to environmental and soil physics variables

    International Nuclear Information System (INIS)

    Thomas, D.M.; Chen, C.; Holford, D.


    During the last three years a field study of soil gas radon activities conducted at Poamoho, Oahu, has shown that the primary environmental variables that control radon transport in shallow tropical soils are synoptic and diurnal barometric pressure changes and soil moisture levels. Barometric pressure changes drive advective transport and mixing of soil gas with atmospheric air; soil moisture appears to control soil porosity and permeability to enhance or inhibit advective and diffusive radon transport. An advective barrier test/control experiment has shown that advective exchange of soil gas and air may account for a substantial proportion of the radon loss from shallow soils but does not significantly affect radon activities at depths greater than 2.3 m. An irrigation test/control experiment also suggests that, at soil moisture levels approaching field capacity, saturation of soil macroporosity can halt all advective transport of radon and limit diffusive mobility to that occurring in the liquid phase. The results of the authors field study have been used to further refine and extend a numerical model, RN3D, that has been developed by Pacific Northwest Laboratories to simulate subsurface transport of radon. The field data have allowed them to accurately simulate the steady state soil gas radon profile at their field site and to track transient radon activities under the influence of barometric pressure changes and in response to changes in soil permeability that result from variations in soil moisture levels. Further work is continuing on the model to enable it to properly account for the relative effects of advective transport of soil gas through cracks and diffusive mobility in the bulk soils

  3. The Influence of Loading Rate and Variable Temperatures on Microbial Communities in Anaerobic Digesters

    Directory of Open Access Journals (Sweden)

    Richard J. Ciotola


    Full Text Available The relationship between seasonal temperatures, organic loading rate (OLR and the structure of archaeal communities in anaerobic digesters was investigated. Previous studies have often assessed archaeal community structure at fixed temperatures and constant OLRs, or at variable temperatures not characteristic of temperate climates. The goal of this study was to determine the maximum OLR that would maintain a balanced microbial ecosystem during operation in a variable temperature range expected in a temperate climate (27–10 °C. Four-liter laboratory digesters were operated in a semi-continuous mode using dairy cow manure as the feedstock. At OLRs of 1.8 and 0.8 kg VS/m3·day the digesters soured (pH < 6.5 as a result of a decrease in temperature. The structure of the archaeal community in the sour digesters became increasingly similar to the manure feedstock with gains in the relative abundance of hydrogenotrophic methanogens. At an OLR of 0.3 kg VS/m3·day the digesters did not sour, but the archaeal community was primarily hydrogenotrophic methanogens. Recommendations for operating an ambient temperature digester year round in a temperate climate are to reduce the OLR to at least 0.3 kg VS/m3·day in colder temperatures to prevent a shift to the microbial community associated with the sour digesters.

  4. New design of a variable-temperature ultrahigh vacuum scanning tunneling microscope

    NARCIS (Netherlands)

    Mugele, Friedrich Gunther; Rettenberger, A.; Boneberg, J.; Leiderer, P.


    We present the design of a variable-temperature ultrahigh vacuum (UHV) scanning tunneling microscope which can be operated between 20 and 400 K. The microscope is mounted directly onto the heat exchanger of a He continuous flow cryostat without vibration isolation inside the UHV chamber. The coarse

  5. Endotracheal temperature and humidity measurements in laryngectomized patients: intra- and inter-patient variability

    NARCIS (Netherlands)

    Scheenstra, R.J.; Muller, S.H.; Vincent, A.; Sinaasappel, M.; Zuur, J.K.; Hilgers, F.J.M.


    This study assesses intra- and inter-patient variability in endotracheal climate (temperature and humidity) and effects of heat and moister exchangers (HME) in 16 laryngectomized individuals, measured repeatedly (N = 47). Inhalation Breath Length (IBL) was 1.35 s without HME and 1.05 s with HME (P <

  6. Endotracheal temperature and humidity measurements in laryngectomized patients: intra- and inter-patient variability

    NARCIS (Netherlands)

    Scheenstra, R. J.; Muller, S. H.; Vincent, A.; Sinaasappel, M.; Zuur, J. K.; Hilgers, Frans J. M.


    This study assesses intra- and inter-patient variability in endotracheal climate (temperature and humidity) and effects of heat and moister exchangers (HME) in 16 laryngectomized individuals, measured repeatedly (N = 47). Inhalation Breath Length (IBL) was 1.35 s without HME and 1.05 s with HME (P

  7. Beyond the mean: the role of variability in predicting ecological effects of stream temperature on salmon (United States)

    E. Ashley Steel; Abby Tillotson; Donald A. Larson; Aimee H. Fullerton; Keith P. Denton; Brian R. Beckman


    Alterations in variance of riverine thermal regimes have been observed and are predicted with climate change and human development. We tested whether changes in daily or seasonal thermal variability, aside from changes in mean temperature, could have biological consequences by exposing Chinook salmon (Oncorhynchus tshawytscha) eggs to eight...

  8. Quantitative assessment of drivers of recent global temperature variability: an information theoretic approach (United States)

    Bhaskar, Ankush; Ramesh, Durbha Sai; Vichare, Geeta; Koganti, Triven; Gurubaran, S.


    Identification and quantification of possible drivers of recent global temperature variability remains a challenging task. This important issue is addressed adopting a non-parametric information theory technique, the Transfer Entropy and its normalized variant. It distinctly quantifies actual information exchanged along with the directional flow of information between any two variables with no bearing on their common history or inputs, unlike correlation, mutual information etc. Measurements of greenhouse gases: CO2, CH4 and N2O; volcanic aerosols; solar activity: UV radiation, total solar irradiance ( TSI) and cosmic ray flux ( CR); El Niño Southern Oscillation ( ENSO) and Global Mean Temperature Anomaly ( GMTA) made during 1984-2005 are utilized to distinguish driving and responding signals of global temperature variability. Estimates of their relative contributions reveal that CO2 ({˜ } 24 %), CH4 ({˜ } 19 %) and volcanic aerosols ({˜ }23 %) are the primary contributors to the observed variations in GMTA. While, UV ({˜ } 9 %) and ENSO ({˜ } 12 %) act as secondary drivers of variations in the GMTA, the remaining play a marginal role in the observed recent global temperature variability. Interestingly, ENSO and GMTA mutually drive each other at varied time lags. This study assists future modelling efforts in climate science.

  9. Is temperature an important variable in recovery after mild traumatic brain injury? [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Coleen M. Atkins


    Full Text Available With nearly 42 million mild traumatic brain injuries (mTBIs occurring worldwide every year, understanding the factors that may adversely influence recovery after mTBI is important for developing guidelines in mTBI management. Extensive clinical evidence exists documenting the detrimental effects of elevated temperature levels on recovery after moderate to severe TBI. However, whether elevated temperature alters recovery after mTBI or concussion is an active area of investigation. Individuals engaged in exercise and competitive sports regularly experience body and brain temperature increases to hyperthermic levels and these temperature increases are prolonged in hot and humid ambient environments. Thus, there is a strong potential for hyperthermia to alter recovery after mTBI in a subset of individuals at risk for mTBI. Preclinical mTBI studies have found that elevating brain temperature to 39°C before mTBI significantly increases neuronal death within the cortex and hippocampus and also worsens cognitive deficits. This review summarizes the pathology and behavioral problems of mTBI that are exacerbated by hyperthermia and discusses whether hyperthermia is a variable that should be considered after concussion and mTBI. Finally, underlying pathophysiological mechanisms responsible for hyperthermia-induced altered responses to mTBI and potential gender considerations are discussed.

  10. Application of Peleg's equation to describe creep responses of potatoes under constant and variable storage conditions. (United States)

    Solomon, W K; Jindal, V K


    The application of Peleg's equation to characterize creep behavior of potatoes during storage was investigated. Potatoes were stored at 25, 15, 5C, and variable (fluctuating) temperature for 16 or 26 weeks. The Peleg equation adequately described the creep response of potatoes during storage at all storage conditions (R 2  = .97to .99). Peleg constant k 1 exhibited a significant (p creep responses during storage or processing will be potentially helpful to better understand the phenomenon. The model parameters from such model could be used to relate rheological properties of raw and cooked potatoes. Moreover, the model parameters could be used to establish relationship between instrumental and sensory attributes which will help in the prediction of sensory attributes from instrumental data. © 2016 Wiley Periodicals, Inc.

  11. Remote SST Forcing and Local Land-Atmosphere Moisture Coupling as Drivers of Amazon Temperature and Carbon Cycle Variability (United States)

    Levine, P. A.; Xu, M.; Chen, Y.; Randerson, J. T.; Hoffman, F. M.


    Interannual variability of climatic conditions in the Amazon rainforest is associated with El Niño-Southern Oscillation (ENSO) and ocean-atmosphere interactions in the North Atlantic. Sea surface temperature (SST) anomalies in these remote ocean regions drive teleconnections with Amazonian surface air temperature (T), precipitation (P), and net ecosystem production (NEP). While SST-driven NEP anomalies have been primarily linked to T anomalies, it is unclear how much the T anomalies result directly from SST forcing of atmospheric circulation, and how much result indirectly from decreases in precipitation that, in turn, influence surface energy fluxes. Interannual variability of P associated with SST anomalies lead to variability in soil moisture (SM), which would indirectly affect T via partitioning of turbulent heat fluxes between the land surface and the atmosphere. To separate the direct and indirect influence of the SST signal on T and NEP, we performed a mechanism-denial experiment to decouple SST and SM anomalies. We used the Accelerated Climate Modeling for Energy (ACMEv0.3), with version 5 of the Community Atmosphere Model and version 4.5 of the Community Land Model. We forced the model with observed SSTs from 1982-2016. We found that SST and SM variability both contribute to T and NEP anomalies in the Amazon, with relative contributions depending on lag time and location within the Amazon basin. SST anomalies associated with ENSO drive most of the T variability at shorter lag times, while the ENSO-driven SM anomalies contribute more to T variability at longer lag times. SM variability and the resulting influence on T anomalies are much stronger in the eastern Amazon than in the west. Comparing modeled T with observations demonstrate that SST alone is sufficient for simulating the correct timing of T variability, but SM anomalies are necessary for simulating the correct magnitude of the T variability. Modeled NEP indicated that variability in carbon fluxes

  12. Variation between cut chrysanthemum cultivars in response to suboptimal temperature

    NARCIS (Netherlands)

    Ploeg, van der A.; Kularathne, R.J.K.N.; Carvalho, S.M.P.; Heuvelink, E.


    To breed for more energy-efficient cut chrysanthemum (Chrysanthemum morifolium Ramat.) cultivars it is important to know the variation of the temperature response existing in modern cultivars. In a greenhouse experiment with 25 chrysanthemum cultivars, a significant variation was observed in

  13. Preparation of temperature responsive fragrance release membranes by UV curing

    International Nuclear Information System (INIS)

    Nakayama, Hiroshi; Kaetsu, Isao; Uchida, Kumao; Okuda, Jyunya; Kitami, Toshiaki; Matsubara, Yoshio


    The authors have studied the preparation and the function of intelligent drug release membranes by UV curing. Temperature responsive fragrance release membranes were prepared by UV curing process and the release functions were investigated as the function of thickness and composition of membrane. Microscopic observations were used to prove the postulated release mechanism

  14. Developmental models for estimating ecological responses to environmental variability: structural, parametric, and experimental issues. (United States)

    Moore, Julia L; Remais, Justin V


    Developmental models that account for the metabolic effect of temperature variability on poikilotherms, such as degree-day models, have been widely used to study organism emergence, range and development, particularly in agricultural and vector-borne disease contexts. Though simple and easy to use, structural and parametric issues can influence the outputs of such models, often substantially. Because the underlying assumptions and limitations of these models have rarely been considered, this paper reviews the structural, parametric, and experimental issues that arise when using degree-day models, including the implications of particular structural or parametric choices, as well as assumptions that underlie commonly used models. Linear and non-linear developmental functions are compared, as are common methods used to incorporate temperature thresholds and calculate daily degree-days. Substantial differences in predicted emergence time arose when using linear versus non-linear developmental functions to model the emergence time in a model organism. The optimal method for calculating degree-days depends upon where key temperature threshold parameters fall relative to the daily minimum and maximum temperatures, as well as the shape of the daily temperature curve. No method is shown to be universally superior, though one commonly used method, the daily average method, consistently provides accurate results. The sensitivity of model projections to these methodological issues highlights the need to make structural and parametric selections based on a careful consideration of the specific biological response of the organism under study, and the specific temperature conditions of the geographic regions of interest. When degree-day model limitations are considered and model assumptions met, the models can be a powerful tool for studying temperature-dependent development.

  15. Evidence for divergence of response in Indica, Japonica, and wild rice to high CO2 x temperature interaction (United States)

    Previous studies suggest that the intraspecific variability of rice yield response to rising carbon dioxide concentration, [CO2], could serve as a basis of selection to improve genotypes for future high CO2 conditions. However, assessment of responses to elevated [CO2] must consider air temperature,...

  16. Responses of hadrons to the chemical potential at finite temperature

    International Nuclear Information System (INIS)

    Choe, S.; Liu, Y.; Miyamura, O.; Forcrand, Ph. de; Garcia Perez, M.; Hioki, S.; Matsufuru, H.; Nakamura, A.; Stamatescu, I.-O.; Takaishi, T.; Umeda, T.


    We present a framework to compute the responses of hadron masses to the chemical potential in lattice QCD simulations. As a first trial, the screening mass of the pseudoscalar meson and its first and second responses are evaluated. We present results on a 16x8 2 x4 lattice with two flavors of staggered quarks below and above T c . The responses to both the isoscalar and isovector chemical potentials are obtained. They show different behavior in the low and the high temperature phases, which may be explained as a consequence of chiral symmetry breaking and restoration, respectively

  17. Temperature- and light-responsive smart polymer materials. (United States)

    Jochum, Florian D; Theato, Patrick


    Stimuli-responsive polymers have been attracting great interest within the scientific community for several decades. The unique feature to respond to small changes in the environmental conditions has made this class of materials very promising for several applications in the field of nanoscience, nanotechnology and nanomedicine. So far, several different chemical, physical or biochemical stimuli have been investigated within natural or synthetic polymers. Very interesting and appealing seems to be the combination of several stimuli to tune the properties of these materials in manifold ways. Within this present review, we want to highlight the recent progress in the field of synthetic stimuli-responsive polymers combining temperature and light responsiveness.

  18. Araucaria growth response to solar and climate variability in South Brazil (United States)

    Prestes, Alan; Klausner, Virginia; Rojahn da Silva, Iuri; Ojeda-González, Arian; Lorensi, Caren


    In this work, the Sun-Earth-climate relationship is studied using tree growth rings of Araucaria angustifolia (Bertol.) O. Kuntze collected in the city of Passo Fundo, located in the state of Rio Grande do Sul (RS), Brazil. These samples were previously studied by Rigozo et al. (2008); however, their main interest was to search for the solar periodicities in the tree-ring width mean time series without interpreting the rest of the periodicities found. The question arises as to what are the drivers related to those periodicities. For this reason, the classical method of spectral analysis by iterative regression and wavelet methods are applied to find periodicities and trends present in each tree-ring growth, in Southern Oscillation Index (SOI), and in annual mean temperature anomaly between the 24 and 44° S. In order to address the aforementioned question, this paper discusses the correlation between the growth rate of the tree rings with temperature and SOI. In each tree-ring growth series, periods between 2 and 7 years were found, possibly related to the El Niño/La Niña phenomena, and a ˜ 23-year period was found, which may be related to temperature variation. These novel results might represent the tree-ring growth response to local climate conditions during its lifetime, and to nonlinear coupling between the Sun and the local climate variability responsible to the regional climate variations.

  19. Role of the Soil Thermal Inertia in the short term variability of the surface temperature and consequences for the soil-moisture temperature feedback (United States)

    Cheruy, Frederique; Dufresne, Jean-Louis; Ait Mesbah, Sonia; Grandpeix, Jean-Yves; Wang, Fuxing


    ) ''hot spots'', it is generally admitted that the variability of the surface temperature is explained by the soil moisture trough its control on the evaporation. This work suggests that the impact of the soil moisture on the temperature through its impact on the thermal inertia can be as important as its direct impact on the evaporation. Contrarily to the evaporation related soil-moisture temperature negative feedback, the thermal inertia soil-moisture related feedback newly identified by this work is a positive feedback which limits the cooling when the soil moisture increases. These results suggest that uncertainties in the representation of the soil and snow thermal properties can be responsible of significant biases in numerical simulations and emphasize the need to carefully document and evaluate these quantities in the Land Surface Modules implemented in the climate models.

  20. Temperature response of soil respiration largely unaltered with experimental warming

    DEFF Research Database (Denmark)

    Carey, Joanna C; Tang, Jianwu; Templer, Pamela H


    The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific...... attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies......, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation...

  1. Temperature and angular dependence of substrate response in SEGR

    International Nuclear Information System (INIS)

    Mouret, I.; Allenspach, M.; Schrimpf, R.D.; Brews, J.R.; Galloway, K.F.


    This work examines the role of the substrate response in determining the temperature and angular dependence of Single-Event Gate Rupture (SEGR). Experimental data indicate that the likelihood of SEGR increases when the temperature of the device is increased or when the incident angle is made closer to normal. In this work, simulations are used to explore this influence of high temperature on SEGR and to support physical explanations for this effect. The reduced hole mobility at high temperature causes the hole concentration at the oxide-silicon interface to be greater, increasing the transient oxide field near the strike position. In addition, numerical calculations show that the transient oxide field decreases as the ion's angle of incidence is changed from normal. This decreased field suggests a lowered likelihood for SEGR, in agreement with the experimental trend

  2. Assessing homogeneity and climate variability of temperature and precipitation series in the capitals of northeastern Brazil (United States)

    Hänsel, Stephanie; Medeiros, Deusdedit; Matschullat, Jörg; Silva, Isamara; Petta, Reinaldo


    A 51-year dataset (1961 to 2011) from nine meteorological stations in the capitals of northeastern Brazil (NEB), with daily data of precipitation totals and of mean, minimum and maximum temperatures, was statistically analyzed for data homogeneity and for signals of climate variability. The hypothesis was explored that a connection exists between inhomogeneities of the time series and the meteorological systems influencing the region. Results of the homogeneity analysis depend on the selected test variable, the test algorithm and the chosen significance level; all more or less subjective choices. Most of the temperature series was classified as "suspect", while most of the precipitation series was categorized as "useful". Displaying and visually checking the time series demonstrates the power of expertise and may allow for a deeper data analysis. Consistent changes in the seasonality of temperature and precipitation emerge over NEB despite manifold breaks in the temperature series. Both series appear to be coupled. The intra-annual temperature and precipitation ranges have increased, along with an intensified seasonal cycle. Temperature mainly increased during DJF, MAM and SON, with decreases in JJA being related to wetter conditions and more frequent heavy precipitation events. Drought conditions mostly increased in SON and DJF, depending on the timing of the local dry season.

  3. Estimation of the temperature spatial variability in confined spaces based on thermal imaging (United States)

    Augustyn, Grzegorz; Jurasz, Jakub; Jurczyk, Krzysztof; Korbiel, Tomasz; Mikulik, Jerzy; Pawlik, Marcin; Rumin, Rafał


    In developed countries the salaries of office workers are several times higher than the total cost of maintaining and operating the building. Therefore even a small improvement in human work productivity and performance as a result of enhancing the quality of their work environment may lead to a meaningful economic benefits. The air temperature is the most commonly used indicator in assessing the indoor environment quality. What is more, it is well known that thermal comfort has the biggest impact on employees performance and their ability to work efficiently. In majority of office buildings, indoor temperature is managed by heating, ventilation and air conditioning (HVAC) appliances. However the way how they are currently managed and controlled leads to the nonhomogeneous distribution of temperature in certain space. An approach to determining the spatial variability of temperature in confined spaces was introduced based on thermal imaging temperature measurements. The conducted research and obtained results enabled positive verification of the method and creation of surface plot illustrating the temperature variability.

  4. Estimation of the temperature spatial variability in confined spaces based on thermal imaging

    Directory of Open Access Journals (Sweden)

    Augustyn Grzegorz


    Full Text Available In developed countries the salaries of office workers are several times higher than the total cost of maintaining and operating the building. Therefore even a small improvement in human work productivity and performance as a result of enhancing the quality of their work environment may lead to a meaningful economic benefits. The air temperature is the most commonly used indicator in assessing the indoor environment quality. What is more, it is well known that thermal comfort has the biggest impact on employees performance and their ability to work efficiently. In majority of office buildings, indoor temperature is managed by heating, ventilation and air conditioning (HVAC appliances. However the way how they are currently managed and controlled leads to the nonhomogeneous distribution of temperature in certain space. An approach to determining the spatial variability of temperature in confined spaces was introduced based on thermal imaging temperature measurements. The conducted research and obtained results enabled positive verification of the method and creation of surface plot illustrating the temperature variability.

  5. Summer temperature and spatial variability of all-cause mortality in Surat city, India

    Directory of Open Access Journals (Sweden)

    S K Rathi


    Full Text Available Background: Ample information is available on extreme heat associated mortality for few Indian cities, but scant literature is available on effect of temperature on spatial variability of all-cause mortality for coastal cities. Objective: To assess the effect of daily maximum temperature, relative humidity and heat index on spatial variability of all-cause mortality for summer months (March to May from 2014 to 2015 for the urban population of Surat (coastal city. Materials and Methods: Retrospective analysis of the all-cause mortality data with temperature and humidity was performed on a total of 9,237 deaths for 184 summer days (2014-2015. Climatic and all-cause mortality data were obtained through Tutiempo website and Surat Municipal Corporation respectively. Bivariate analysis performed through SPSS. Observations: Mean daily mortality was estimated at 50.2 ± 8.5 for the study period with a rise of 20% all-cause mortality at temperature ≥ 40°C and rise of 10% deaths per day during extreme danger level (HI: > 54°C days. Spatial (Zone wise analysis revealed rise of 61% all-cause mortality for Southeast and 30% for East zones at temperature ≥ 40°C. Conclusions: All-cause mortality increased on high summer temperature days. Presence of spatial variation in all-cause mortality provided the evidence for high risk zones. Findings may be helpful in designing the interventions at micro level.

  6. Local and linear chemical reactivity response functions at finite temperature in density functional theory

    International Nuclear Information System (INIS)

    Franco-Pérez, Marco; Ayers, Paul W.; Gázquez, José L.; Vela, Alberto


    We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model

  7. In situ response time measurements of RTD temperature sensors

    International Nuclear Information System (INIS)

    Goncalves, I.M.P.


    The loop-current-step-response test provides a mean for determining the time constant of resistence thermometers. The test consist in heating the sensor a few degrees above ambient temperature by causing a step pertubation in the electric current that flows through the sensor leads. The developed mathematical transformation permits to use data collected during the internal heating transient to predict the sensor response to perturbations in fluid temperature. Experimental data obtained show that the time constant determined by method is within 15 percent of true value. The loop-current-step-response test is a remote in situ test, which can be performed with the sensor installed in the process. Consequently it takes account the local heat transfer conditions, and appropriated for nuclear power plants, where sensors are installed in points of difficult access. (author) [pt

  8. Impact of the Dominant Large-scale Teleconnections on Winter Temperature Variability over East Asia (United States)

    Lim, Young-Kwon; Kim, Hae-Dong


    Monthly mean geopotential height for the past 33 DJF seasons archived in Modern Era Retrospective analysis for Research and Applications reanalysis is decomposed into the large-scale teleconnection patterns to explain their impacts on winter temperature variability over East Asia. Following Arctic Oscillation (AO) that explains the largest variance, East Atlantic/West Russia (EA/WR), West Pacific (WP) and El Nino-Southern Oscillation (ENSO) are identified as the first four leading modes that significantly explain East Asian winter temperature variation. While the northern part of East Asia north of 50N is prevailed by AO and EA/WR impacts, temperature in the midlatitudes (30N-50N), which include Mongolia, northeastern China, Shandong area, Korea, and Japan, is influenced by combined effect of the four leading teleconnections. ENSO impact on average over 33 winters is relatively weaker than the impact of the other three teleconnections. WP impact, which has received less attention than ENSO in earlier studies, characterizes winter temperatures over Korea, Japan, and central to southern China region south of 30N mainly by advective process from the Pacific. Upper level wave activity fluxes reveal that, for the AO case, the height and circulation anomalies affecting midlatitude East Asian winter temperature is mainly located at higher latitudes north of East Asia. Distribution of the fluxes also explains that the stationary wave train associated with EA/WR propagates southeastward from the western Russia, affecting the East Asian winter temperature. Investigation on the impact of each teleconnection for the selected years reveals that the most dominant teleconnection over East Asia is not the same at all years, indicating a great deal of interannual variability. Comparison in temperature anomaly distributions between observation and temperature anomaly constructed using the combined effect of four leading teleconnections clearly show a reasonable consistency between

  9. Temperature effects on zoeal morphometric traits and intraspecific variability in the hairy crab Cancer setosus across latitude (United States)

    Weiss, Monika; Thatje, Sven; Heilmayer, Olaf


    Phenotypic plasticity is an important but often ignored ability that enables organisms, within species-specific physiological limits, to respond to gradual or sudden extrinsic changes in their environment. In the marine realm, the early ontogeny of decapod crustaceans is among the best known examples to demonstrate a temperature-dependent phenotypic response. Here, we present morphometric results of larvae of the hairy crab Cancer setosus, the embryonic development of which took place at different temperatures at two different sites (Antofagasta, 23°45' S; Puerto Montt, 41°44' S) along the Chilean Coast. Zoea I larvae from Puerto Montt were significantly larger than those from Antofagasta, when considering embryonic development at the same temperature. Larvae from Puerto Montt reared at 12 and 16°C did not differ morphometrically, but sizes of larvae from Antofagasta kept at 16 and 20°C did, being larger at the colder temperature. Zoea II larvae reared in Antofagasta at three temperatures (16, 20, and 24°C) showed the same pattern, with larger larvae at colder temperatures. Furthermore, larvae reared at 24°C, showed deformations, suggesting that 24°C, which coincides with temperatures found during strong EL Niño events, is indicative of the upper larval thermal tolerance limit. C. setosus is exposed to a wide temperature range across its distribution range of about 40° of latitude. Phenotypic plasticity in larval offspring does furthermore enable this species to locally respond to the inter-decadal warming induced by El Niño. Morphological plasticity in this species does support previously reported energetic trade-offs with temperature throughout early ontogeny of this species, indicating that plasticity may be a key to a species’ success to occupy a wide distribution range and/or to thrive under highly variable habitat conditions.

  10. Connecting Atlantic temperature variability and biological cycling in two earth system models (United States)

    Gnanadesikan, Anand; Dunne, John P.; Msadek, Rym


    Connections between the interdecadal variability in North Atlantic temperatures and biological cycling have been widely hypothesized. However, it is unclear whether such connections are due to small changes in basin-averaged temperatures indicated by the Atlantic Multidecadal Oscillation (AMO) Index, or whether both biological cycling and the AMO index are causally linked to changes in the Atlantic Meridional Overturning Circulation (AMOC). We examine interdecadal variability in the annual and month-by-month diatom biomass in two Earth System Models with the same formulations of atmospheric, land, sea ice and ocean biogeochemical dynamics but different formulations of ocean physics and thus different AMOC structures and variability. In the isopycnal-layered ESM2G, strong interdecadal changes in surface salinity associated with changes in AMOC produce spatially heterogeneous variability in convection, nutrient supply and thus diatom biomass. These changes also produce changes in ice cover, shortwave absorption and temperature and hence the AMO Index. Off West Greenland, these changes are consistent with observed changes in fisheries and support climate as a causal driver. In the level-coordinate ESM2M, nutrient supply is much higher and interdecadal changes in diatom biomass are much smaller in amplitude and not strongly linked to the AMO index.

  11. Compound extremes of summer temperature and precipitation leading to intensified departures from natural variability. (United States)

    Mahony, C. R.; Cannon, A. J.


    Climate change can drive local climates outside the range of their historical year-to-year variability, straining the adaptive capacity of ecological and human communities. We demonstrate that interactions between climate variables can produce larger and earlier departures from natural variability than is detectable in individual variables. For example, summer temperature (Tx) and precipitation (Pr) are negatively correlated in most terrestrial regions, such that interannual variability lies along an axis from warm-and-dry to cool-and-wet conditions. A climate change trend perpendicular to this axis, towards warmer-wetter conditions, can depart more quickly from the range of natural variability than a warmer-drier trend. This multivariate "departure intensification" effect is evident in all six CMIP5 models that we examined: 23% (9-34%) of the land area of each model exhibits a pronounced increase in 2σ extremesin the Tx-Pr regime relative to Tx or Pr alone. Observational data suggest that Tx-Pr correlations are sufficient to produce departure intensification in distinct regions on all continents. Departures from the historical Tx-Pr regime may produce ecological disruptions, such as in plant-pathogen interactions and human diseases, that could offset the drought mitigation benefits of increased precipitation. Our study alerts researchers and adaptation practitioners to the presence of multivariate climate change signals and compound extremes that are not detectable in individual climate variables.

  12. The intraseasonal variability of winter semester surface air temperature in Antarctica

    Directory of Open Access Journals (Sweden)

    Lejiang Yu


    Full Text Available This study investigates systematically the intraseasonal variability of surface air temperature over Antarctica by applying empirical orthogonal function (EOF analysis to the National Centers for Environmental Prediction, US Department of Energy, Reanalysis 2 data set for the period of 1979 through 2007. The results reveal the existence of two major intraseasonal oscillations of surface temperature with periods of 26–30 days and 14 days during the Antarctic winter season in the region south of 60°S. The first EOF mode shows a nearly uniform spatial pattern in Antarctica and the Southern Ocean associated with the Antarctic Oscillation. The mode-1 intraseasonal variability of the surface temperature leads that of upper atmosphere by one day with the largest correlation at 300-hPa level geopotential heights. The intraseasonal variability of the mode-1 EOF is closely related to the variations of surface net longwave radiation the total cloud cover over Antarctica. The other major EOF modes reveal the existence of eastward propagating phases over the Southern Ocean and marginal region in Antarctica. The leading two propagating modes respond to Pacific–South American modes. Meridional winds induced by the wave train from the tropics have a direct influence on the surface air temperature over the Southern Ocean and the marginal region of the Antarctic continent.

  13. Temperature-responsive chromatography for the separation of biomolecules. (United States)

    Kanazawa, Hideko; Okano, Teruo


    Temperature-responsive chromatography for the separation of biomolecules utilizing poly(N-isopropylacrylamide) (PNIPAAm) and its copolymer-modified stationary phase is performed with an aqueous mobile phase without using organic solvent. The surface properties and function of the stationary phase are controlled by external temperature changes without changing the mobile-phase composition. This analytical system is based on nonspecific adsorption by the reversible transition of a hydrophilic-hydrophobic PNIPAAm-grafted surface. The driving force for retention is hydrophobic interaction between the solute molecules and the hydrophobized polymer chains on the stationary phase surface. The separation of the biomolecules, such as nucleotides and proteins was achieved by a dual temperature- and pH-responsive chromatography system. The electrostatic and hydrophobic interactions could be modulated simultaneously with the temperature in an aqueous mobile phase, thus the separation system would have potential applications in the separation of biomolecules. Additionally, chromatographic matrices prepared by a surface-initiated atom transfer radical polymerization (ATRP) exhibit a strong interaction with analytes, because the polymerization procedure forms a densely packed polymer, called a polymer brush, on the surfaces. The copolymer brush grafted surfaces prepared by ATRP was an effective tool for separating basic biomolecules by modulating the electrostatic and hydrophobic interactions. Applications of thermally responsive columns for the separations of biomolecules are reviewed here. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Temperature-responsive PLLA/PNIPAM nanofibers for switchable release

    Energy Technology Data Exchange (ETDEWEB)

    Elashnikov, Roman; Slepička, Petr [Department of Solid State Engineering, University of Chemistry and Technology, Prague 166 28 (Czech Republic); Rimpelova, Silvie; Ulbrich, Pavel [Department of Biochemistry and Microbiology, University of Chemistry and Technology, 16628 Prague (Czech Republic); Švorčík, Vaclav [Department of Solid State Engineering, University of Chemistry and Technology, Prague 166 28 (Czech Republic); Lyutakov, Oleksiy, E-mail: [Department of Solid State Engineering, University of Chemistry and Technology, Prague 166 28 (Czech Republic)


    Smart antimicrobial materials with on-demand drug release are highly desired for biomedical applications. Herein, we report about temperature-responsive poly(N-isopropylacrylamide) (PNIPAM) nanospheres doped with crystal violet (CV) and incorporated into the poly-L-lactide (PLLA) nanofibers. The nanofibers were prepared by electrospinning, using different initial polymers ratios. The morphology of the nanofibers and polymers distribution in the nanofibers were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The interaction between PNIPAM and PLLA in the nanofibers was studied by Fourier transform infrared spectroscopy (FTIR) and its effect on the PNIPAM phase transition was also investigated. It was shown that by the changing of the environmental temperature across the lower critical solution temperature (LCST) of PNIPAM, the switchable wettability and controlled CV release can be achieved. The temperature-dependent release kinetics of CV from polymer nanofibers was investigated by ultraviolet-visible spectroscopy (UV–Vis). The temperature-responsive release of antibacterial CV was also tested for triggering of antibacterial activity, which was examined on Staphylococcus epidermidis (S. epidermidis) and Escherichia coli (E. coli). Thus, the proposed material is promising value for controllable drug-release.

  15. Thermodynamics of U(VI) complexation by succinate at variable temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Rawat, Neetika [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Tomar, B.S., E-mail: [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Manchanda, V.K. [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)


    Research highlights: > lg {beta} and {Delta}H{sub C} for U(VI)-succinate determined at variable temperatures. > Increase in lg {beta} with temperature well explained by Born equation. > {Delta}S{sub C} plays the dominant role in variation of {Delta}G{sub C} with temperature. > {Delta}H{sub C} for U(VI)-succinate increases linearly with temperature. > {Delta}C{sub P} of U(VI)-succinate is higher than that of oxalate and malonate complexes. - Abstract: Complexation of U(VI) by succinate has been studied at various temperatures in the range of (298 to 338) K by potentiometry and isothermal titration calorimetry at constant ionic strength (1.0 M). The potentiometric titrations revealed the formation of 1:1 uranyl succinate complex in the pH range of 1.5 to 4.5. The stability constant of uranyl succinate complex was found to increase with temperature. Similar trend was observed in the case of enthalpy of complex formation. However, the increase in entropy with temperature over-compensated the increase in enthalpy, thereby favouring the complexation reaction at higher temperatures. The linear increase of enthalpy of complexation with temperature indicates constancy of the change in heat capacity during complexation. The temperature dependence of stability constant data was well explained with the help of Born equation for electrostatic interaction between the metal ion and the ligand. The data have been compared with those for uranyl complexes with malonate and oxalate to study the effect of ligand size and hydrophobicity on the temperature dependence of thermodynamic quantities.

  16. 630 understanding farmers' response to climate variability in nigeria

    African Journals Online (AJOL)


    Data were analyzed using descriptive statistics, and multinomial logit models. Farmers used multiple adaptation strategies; Crop Diversification (CD), Soil ... Increases in temperature, cloud ... and the effect of climate elements and their extreme ...

  17. Variation in the transcriptional response of threatened coral larvae to elevated temperatures. (United States)

    Polato, Nicholas R; Altman, Naomi S; Baums, Iliana B


    Coral populations have declined worldwide largely due to increased sea surface temperatures. Recovery of coral populations depends in part upon larval recruitment. Many corals reproduce during the warmest time of year when further increases in temperature can lead to low fertilization rates of eggs and high larval mortality. Microarray experiments were designed to capture and assess variability in the thermal stress responses of Acropora palmata larvae from Puerto Rico. Transcription profiles showed a striking acceleration of normal developmental gene expression patterns with increased temperature. The transcriptional response to heat suggested rapid depletion of larval energy stores via peroxisomal lipid oxidation and included key enzymes that indicated the activation of the glyoxylate cycle. High temperature also resulted in expression differences in key developmental signalling genes including the conserved WNT pathway that is critical for pattern formation and tissue differentiation in developing embryos. Expression of these and other important developmental and thermal stress genes such as ferritin, heat shock proteins, cytoskeletal components, cell adhesion and autophagy proteins also varied among larvae derived from different parent colonies. Disruption of normal developmental and metabolic processes will have negative impacts on larval survival and dispersal as temperatures rise. However, it appears that variation in larval response to high temperature remains despite the dramatic population declines. Further research is needed to determine whether this variation is heritable or attributable to maternal effects. © 2013 Blackwell Publishing Ltd.

  18. Variability in cell response of Cronobacter sakazakii after mild-heat treatments and its impact on food safety

    Directory of Open Access Journals (Sweden)

    Julio eParra-Flores


    Full Text Available Cronobacter spp. have been responsible for severe infections in infants associated with consumption of powdered infant formula (PIF and follow-up formulae (FUF. Despite several risk assessments described in published studies, few approaches have considered the tremendous variability in cell response that small micropopulations or single cells can have in infant formula during storage, preparation or post process/preparation before the feeding of infants. Stochastic approaches can better describe microbial single cell response than deterministic models as we prove in this study. A large variability of lag phase was observed in single cell and micropopulations of ≤50 cells. This variability increased as the heat shock increased and growth temperature decreased. Obviously, variability of growth of individual Cronobacter sakazakii cell is affected by inoculum size, growth temperature and the probability of cells able to grow at the conditions imposed by the experimental conditions should be taken into account, especially when errors in bottle-preparation practices, such as improper holding temperatures or manipulation, may lead to growth of the pathogen to a critical cell level. The mean probability of illness from initial inoculum size of 1 cell were below 0.2 in all the cases and for inoculum size of 50 cells the mean probability of illness were, in most of the cases, was above 0.7.

  19. Time response of temperature sensors using neural networks

    International Nuclear Information System (INIS)

    Santos, Roberto Carlos dos


    In a PWR nuclear power plant, the primary coolant temperature and feedwater temperature are measured using RTDs (Resistance Temperature Detectors). These RTDs typically feed the plant's control and safety systems and must, therefore, be very accurate and have good dynamic performance. The response time of RTDs is characterized by a single parameter called the Plunge Time Constant defined as the time it takes the sensor output to achieve 63.2 percent of its final value after a step change in temperature. Nuclear reactor service conditions are difficult to reproduce in the laboratory, and an in-situ test method called LCSR (Loop Current Step Response) test was developed to measure remotely the response time of RTDs. >From this test, the time constant of the sensor is identified by means of the LCSR transformation that involves the dynamic response modal time constants determination using a nodal heat-transfer model. This calculation is not simple and requires specialized personnel. For this reason an Artificial Neural Network has been developed to predict the time constant of RTD from LCSR test transient. It eliminates the transformations involved in the LCSR application. A series of LCSR tests on RTDs generates the response transients of the sensors, the input data of the networks. Plunge tests are used to determine the time constants of the RTDs, the desired output of the ANN, trained using these sets of input/output data. This methodology was firstly applied to theoretical data simulating 10 RTDs with different time constant values, resulting in an average error of about 0.74 %. Experimental data from three different RTDs was used to predict time constant resulting in a maximum error of 3,34 %. The time constants values predicted from ANN were compared with those obtained from traditional way resulting in an average error of about 18 % and that shows the network is able to predict accurately the sensor time constant. (author)

  20. A variable temperature cryostat that produces in situ clean-up germanium detector surfaces

    International Nuclear Information System (INIS)

    Pehl, R.H.; Madden, N.W.; Malone, D.F.; Cork, C.P.; Landis, D.A.; Xing, J.S.; Friesel, D.L.


    Variable temperature cryostats that can maintain germanium detectors at temperatures from 82 K to about 400 K while the thermal shield surrounding the detectors remains much colder when the detectors are warmed have been developed. Cryostats such as these offer the possibility of cryopumping material from the surface of detectors to the colder thermal shield. The diode characteristics of several detectors have shown very significant improvement following thermal cycles up to about 150 K in these cryostats. Important applications for cryostats having this attribute are many. 4 figs

  1. Viscous and Joule heating effects on MHD free convection flow with variable plate temperature

    International Nuclear Information System (INIS)

    Hossain, M.A.


    A steady two-dimensional laminar boundary layer flow of a viscous incompressible and electrically conducting fluid past a vertical heated plate with variable temperature in the presence of a transverse uniform magnetic field has been investigated by bringing the effect of viscous and Joules heating. The non-dimensional boundary layer equations are solved using the implicit finite difference method along with Newton's approximation for small Prandtl number chosen as typical of coolant liquid metals at operating temperature. (author). 10 refs, 2 figs, 1 tab

  2. Optimization and Modeling of Process Variables of Biodiesel Production from Marula Oil using Response Surface Methodology

    International Nuclear Information System (INIS)

    Enweremadu, C. C.; Rutto, H. L.


    This paper presents an optimization study in the production of biodiesel production from Marula oil. The study was carried out using a central composite design of experiments under response surface methodology. A mathematical model was developed to correlate the transesterification process variables to biodiesel yield. The transesterification reaction variables were methanol to oil ratio, x /sub 1/ (10-50 wt percentage), reaction time, x /sub 2/ (30-90 min), reaction temperature, x /sub 3/ (30-90 Degree C) stirring speed, x /sub 4/ (100-400 rpm) and amount of catalyst, x /sub 5/ (0.5-1.5 g). The optimum conditions for the production of the biodiesel were found to be methanol to oil ratio (29.43 wt percentage), reaction time (59.17 minutes), reaction temperature (58.80 Degree C), stirring speed (325 rpm) and amount of catalyst (1.02 g). The optimum yield of biodiesel that can be produced was 95 percentage. The results revealed that the crucial fuel properties of the biodiesel produced at the optimum conditions met the ASTM biodiesel specifications. (author)

  3. Long-term temperature trends and variability on Spitsbergen: the extended Svalbard Airport temperature series, 1898–2012

    Directory of Open Access Journals (Sweden)

    Øyvind Nordli


    Full Text Available One of the few long instrumental records available for the Arctic is the Svalbard Airport composite series that hitherto began in 1911, with observations made on Spitsbergen, the largest island in the Svalbard Archipelago. This record has now been extended to 1898 with the inclusion of observations made by hunting and scientific expeditions. Temperature has been observed almost continuously in Svalbard since 1898, although at different sites. It has therefore been possible to create one composite series for Svalbard Airport covering the period 1898–2012, and this valuable new record is presented here. The series reveals large temperature variability on Spitsbergen, with the early 20th century warming as one striking feature: an abrupt change from the cold 1910s to the local maxima of the 1930s and 1950s. With the inclusion of the new data it is possible to show that the 1910s were colder than the years at the start of the series. From the 1960s, temperatures have increased, so the present temperature level is significantly higher than at any earlier period in the instrumental history. For the entire period, and for all seasons, there are positive, statistically significant trends. Regarding the annual mean, the total trend is 2.6°C/century, whereas the largest trend is in spring, at 3.9°C/century. In Europe, it is the Svalbard Archipelago that has experienced the greatest temperature increase during the latest three decades. The composite series may be downloaded from the home page of the Norwegian Meteorological Institute and should be used with reference to the present article.

  4. Northern goshawk broadcast surveys: Hawk response variables and survey cost (United States)

    Suzanne M. Joy; Richard T. Reynolds; Douglas G. Leslie


    We examined responses of Northern Goshawks (Accipter gentilis) to taped broadcast calls of conspecifics in tree-harvest areas and around alternate goshawk nests on Kaibab National Forest, Arizona, in 1991 and 1992. Forest areas totaling 476 km2 were systematically surveyed for goshawks. Ninety responses by adult and juvenile goshawks were elicited...

  5. An analysis of surface air temperature trends and variability along the Andes (United States)

    Franquist, Eric S.

    Climate change is difficult to study in mountainous regions such as the Andes since steep changes in elevation cannot always be resolved by climate models. However, it is important to examine temperature trends in this region as rises in surface air temperature are leading to the melting of tropical glaciers. Local communities rely on the glacier-fed streamflow to get their water for drinking, irrigation, and livestock. Moreover, communities also rely on the tourism of hikers who come to the region to view the glaciers. As the temperatures increase, these glaciers are no longer in equilibrium with their current climate and are receding rapidly and decreasing the streamflow. This thesis examines surface air temperature from 858 weather stations across Ecuador, Peru, and Chile in order to analyze changes in trends and variability. Three time periods were studied: 1961--1990, 1971--2000, and 1981--2010. The greatest warming occurred during the period of 1971--2000 with 92% of the stations experiencing positive trends with a mean of 0.24°C/decade. There was a clear shift toward cooler temperatures at all latitudes and below elevations of 500 m during the most recent time period studied (1981--2010). Station temperatures were more strongly correlated with the El Nino Southern Oscillation (ENSO), than the Pacific Decadal Oscillation (PDO), and the Southern Annular Mode (SAM). A principal component analysis confirmed ENSO as the main contributor of variability with the most influence in the lower latitudes. There were clear multidecadal changes in correlation strength for the PDO. The PDO contributed the most to the increases in station temperature trends during the 1961--1990 period, consistent with the PDO shift to the positive phase in the middle of this period. There were many strong positive trends at individual stations during the 1971--2000 period; however, these trends could not fully be attributed to ENSO, PDO, or SAM, indicating anthropogenic effects of

  6. An advanced straight tube heat exchanger in which a fluid flows at variable and elevated temperatures

    International Nuclear Information System (INIS)

    Mauget, C.; Benoit, G.; Stalport, G.


    Straight tube heat exchangers are used as steam generators in nuclear reactors such as in fast neutron nuclear power plants; elevated and highly variable temperatures induce very high thermal expansion constraints in these long straight tubes. In order to avoid the expansion problems, an expansion bellow is disposed between the heat exchanger and the collector tubular plate in such a way that the bundle differential expansions may be absorbed

  7. Electromechanical characterization of piezoelectric actuators subjected to a variable pre-loading force at cryogenic temperature

    International Nuclear Information System (INIS)

    Fouaidy, M.; Saki, M.; Hammoudi, N.; Simonet, L.


    A dedicated apparatus was designed and constructed for studying the electromechanical behavior of prototype piezoelectric actuators subjected to a variable pre-loading force at cryogenic temperatures. This device was successfully used for testing a piezoelectric actuator of PICMA type from PI TM , for T in the range 2 K-300 K. The dielectric properties as well as dynamic properties were measured including the actuator characteristics when used as force sensor. The corresponding data are reported and discussed. (authors)

  8. Heightened fire risk in Indonesia in response to increasing temperature (United States)

    Fernandes, K.; Baethgen, W.; Verchot, L. V.; Gutierrez-Velez, V.; Pinedo-Vasquez, M.


    In Indonesia, drought driven fires occur typically during the warm phase of the El Niño Southern Oscillation (ENSO), such as those of 1997 and 2015 that resulted in months-long hazardous atmospheric pollution levels in Equatorial Asia and record greenhouse gas emissions. Nonetheless, anomalously active fire seasons have also been observed in non-drought years. In this work, we investigated whether fires are impacted by temperature anomalies and if so, if the responses differ under contrasting precipitation regimes. Our findings show that when the July-October dry-season is anomalously dry, the sensitivity of fires to temperature anomalies is similar regardless of the sign of the anomalies. In contrast, in wet condition, fire risk increases sharply when the dry season is anomalously warm. We also present a characterization of near-term regional climate projections over the next few decades and the implications of continuing global temperature increase in future fire probability in Indonesia.

  9. Last nine-thousand years of temperature variability in Northern Europe

    Directory of Open Access Journals (Sweden)

    H. Seppä


    Full Text Available The threat of future global warming has generated a major interest in quantifying past climate variability on centennial and millennial time-scales. However, palaeoclimatological records are often noisy and arguments about past variability are only possible if they are based on reproducible features in several reliably dated datasets. Here we focus on the last 9000 years, explore the results of 36 Holocene pollen-based July mean and annual mean temperature reconstructions from Northern Europe by stacking them to create summary curves, and compare them with a high-resolution, summary chironomid-based temperature record and other independent palaeoclimate records. The stacked records show that the "Holocene Thermal Maximum" in the region dates to 8000 to 4800 cal yr BP and that the "8.2 event" and the "Little Ice Age" at 500–100 cal yr BP are the clearest cold episodes during the Holocene. In addition, a more detailed analysis of the last 5000 years pinpoints centennial-scale climate variability with cold anomalies at 3800–3000 and 500–100 cal yr BP, a long, warmer period around 2000 cal yr BP, and a marked warming since the mid 19th century. The colder (warmer anomalies are associated with increased (decreased humidity over the northern European mainland, consistent with the modern high correlation between cold (warm and humid (dry modes of summer weather in the region. A comparison with the key proxy records reflecting the main forcing factors does not support the hypothesis that solar variability is the cause of the late-Holocene centennial-scale temperature changes. We suggest that the reconstructed anomalies are typical of Northern Europe and their occurrence may be related to the oceanic and atmospheric circulation variability in the North Atlantic – North-European region.

  10. The Nitrocarburising Response of Low Temperature Bainite Steel

    Directory of Open Access Journals (Sweden)

    Daniel Fabijanic


    Full Text Available The nitrocarburising response of low transformation temperature ultrafine and nanoscale bainitic steel was investigated and compared with martensite and pearlite from the same steel composition. It was found that the retained austenite content of the bainitic steel dictated the core hardness after nitrocarburising. The refined bainitic structure showed improvements in the nitriding depth and hardness of the nitrocarburised layer, compared to coarser grained martensitic and pearlitic structures, possibly due to the fine structure and the distribution of nitride forming elements.

  11. Variable prognostic value of blood pressure response to exercise. (United States)

    Kato, Yuko; Suzuki, Shinya; Uejima, Tokuhisa; Semba, Hiroaki; Yamashita, Takeshi


    The aim of this study was to evaluate the impact of patient background including exercise capacity on the relationship between the blood pressure (BP) response to exercise and prognosis in patients visiting a cardiovascular hospital. A total of 2134 patients who were referred to our hospital underwent symptom-limited maximal cardiopulmonary exercise testing, and were followed through medical records and mail. The BP response to exercise was defined as the difference between peak and rest systolic BP. The end point was set as cardiovascular events including cardiovascular death, acute coronary syndrome, hospitalization for heart failure, and cerebral infarction. During a median follow-up period of 3 years, 179 (8%) patients reached the end point (2.5%/year). Multivariate analysis showed that BP response was independently and negatively associated with the occurrence of the end point. This prognostic significance of BP response was consistent regardless of left ventricular ejection fraction, renal function, presence of heart failure symptoms, the presence of organic heart disease, and hypertension. However, peak VO 2 showed a significant interaction with the effects of BP response on the end point, suggesting that the prognostic value of BP response was limited in patients with preserved exercise capacity. The role of BP response to exercise as the predictor depends on exercise capacity of each patient. Copyright © 2017 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  12. Influence of temperature in polymethylmethacrylate (PMMA) dosemeters response

    International Nuclear Information System (INIS)

    Napolitano, Celia Marina; Ferreira, Danilo Cardenuto; Camargo, Fabio de; Goncalves, Josemary Angelica Correa; Tobias, Carmen Cecilia Bueno


    The use of gamma irradiation sterilization processes in medical products and food preservation has encouraged the emergence of industrial facilities responsible for generation of doses as high as a few dozen kGy. The characterization of this radiation field requires the use of dosimeters with high spatial resolution, high resistance to radiation damage, maintenance of information absorbed doses at a time suitable for the analysis and processing of data, easy handling, etc. The dosimeters that meet most of these requirements are based on polymethylmethacrylate (PMMA) with dyes sensitive to radiation. The dose that can be measured with these dosimeters extends from 100Gy to 50kGy, with the estimated accuracies by manufacturers from 2 to 3%. However, in practice, there are procedures that require irradiation in different conditions of temperature, which results in changes in the response of the dosimeter. This way, considering the irradiations made in the center of radiation technology of Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP - Brazilian nuclear and energy research institute -, has studied the effect of temperature on the response of routine dosimeters PMMA type where the operational characteristics of Gammachrome YR dosimeters type and Red Perspex are being investigated respect to temperature and dose, whose results will be presented in this paper

  13. Analysis of the response of a photovoltaic module subjected to pulsating light of variable duty cycle

    International Nuclear Information System (INIS)

    Zuñiga-Reyes, Marco A.; Sevilla-Camacho, P.Y.; Robles-Ocampo, J.B.; Lopez-Villarea, S. A.


    The present work analyzes the time domain response of polycrystalline and amorphous silicon modules subjected to a pulsed light signal, applied under conditions of darkness and controlled temperature. The applied light has a wavelength of 625 nm, a constant power of 5 Watts, a constant frequency of 10 kHz and a variable duty cycle. The response of the modules was analyzed in both direct current (DC) and alternating current (AC). The results of the research showed differences between the waveform and the amplitude of the output voltage of each of the manufacturing technologies of the modules. To validate the obtained results, the simulation of the response of a solar cell using its equivalent circuit in CA was performed. From the experimental and simulation tests it is observed that the relation between the duty cycle and the response of the modules of different technologies can be used for the monitoring and detection of faults or for the determination of the components of the AC equivalent circuit from the solar cells. (author)

  14. Temperature response functions introduce high uncertainty in modelled carbon stocks in cold temperature regimes (United States)

    Portner, H.; Wolf, A.; Bugmann, H.


    Many biogeochemical models have been applied to study the response of the carbon cycle to changes in climate, whereby the process of carbon uptake (photosynthesis) has usually gained more attention than the equally important process of carbon release by respiration. The decomposition of soil organic matter is driven by a combination of factors with a prominent one being soil temperature [Berg and Laskowski(2005)]. One uncertainty concerns the response function used to describe the sensitivity of soil organic matter decomposition to temperature. This relationship is often described by one out of a set of similar exponential functions, but it has not been investigated how uncertainties in the choice of the response function influence the long term predictions of biogeochemical models. We built upon the well-established LPJ-GUESS model [Smith et al.(2001)]. We tested five candidate functions and calibrated them against eight datasets from different Ameriflux and CarboEuropeIP sites [Hibbard et al.(2006)]. We used a simple Exponential function with a constant Q10, the Arrhenius function, the Gaussian function [Tuomi et al.(2008), O'Connell(1990)], the Van't Hoff function [Van't Hoff(1901)] and the Lloyd&Taylor function [Lloyd and Taylor(1994)]. We assessed the impact of uncertainty in model formulation of temperature response on estimates of present and future long-term carbon storage in ecosystems and hence on the CO2 feedback potential to the atmosphere. We specifically investigated the relative importance of model formulation and the error introduced by using different data sets for the parameterization. Our results suggested that the Exponential and Arrhenius functions are inappropriate, as they overestimated the respiration rates at lower temperatures. The Gaussian, Van't Hoff and Lloyd&Taylor functions all fit the observed data better, whereby the functions of Gaussian and Van't Hoff underestimated the response at higher temperatures. We suggest, that the

  15. Large temperature variability in the southern African tropics since the Last Glacial Maximum

    NARCIS (Netherlands)

    Powers, L.A.; Johnson, T.C.; Werne, J.P.; Castañeda, I.S.; Hopmans, E.; Sinninghe Damsté, J.S.; Schouten, S.


    The role of the tropics in global climate change is actively debated, particularly in regard to the timing and magnitude of thermal and hydrological response. Continuous, high-resolution temperature records through the Last Glacial Maximum (LGM) from tropical oceans have provided much insight

  16. Potential forcings of summer temperature variability of the southeastern Tibetan Plateau in the past 12 ka (United States)

    Zhang, Enlou; Chang, Jie; Sun, Weiwei; Cao, Yanmin; Langdon, Peter; Cheng, Jun


    Investigating potential forcing mechanisms of terrestrial summer temperature changes from the Asian summer monsoon influenced area is of importance to better understand the climate variability in these densely populated regions. The results of spectral and wavelet analyses of the published chironomid reconstructed mean July temperature data from Tiancai Lake on the SE Tibetan Plateau are presented. The evidence of solar forcing of the summer temperature variability from the site on centennial timescales where key solar periodicities (at 855 ± 40, 465 ± 40, 315 ± 40 and 165 ± 40 year) are revealed. By using a band-pass filter, coherent fluctuations were found in the strength of Asian summer monsoon, Northern Hemisphere high latitude climate and high elevation mid-latitude (26°N) terrestrial temperatures with solar sunspot cycles since about 7.6 ka. The two abrupt cooling events detected from the Tiancai Lake record, centered at ∼9.7 and 3.5 ka were examined respectively. Coupled with the paleoclimate modeling results, the early Holocene event (9.7 ka) is possibly linked to an ocean-atmospheric feedback mechanism whereas the latter event (3.5 ka) may be more directly related to external forcing.

  17. Demonstration of a Variable Phase Turbine Power System for Low Temperature Geothermal Resources

    Energy Technology Data Exchange (ETDEWEB)

    Hays, Lance G


    A variable phase turbine assembly will be designed and manufactured having a turbine, operable with transcritical, two-phase or vapor flow, and a generator – on the same shaft supported by process lubricated bearings. The assembly will be hermetically sealed and the generator cooled by the refrigerant. A compact plate-fin heat exchanger or tube and shell heat exchanger will be used to transfer heat from the geothermal fluid to the refrigerant. The demonstration turbine will be operated separately with two-phase flow and with vapor flow to demonstrate performance and applicability to the entire range of low temperature geothermal resources. The vapor leaving the turbine is condensed in a plate-fin refrigerant condenser. The heat exchanger, variable phase turbine assembly and condenser are all mounted on single skids to enable factory assembly and checkout and minimize installation costs. The system will be demonstrated using low temperature (237F) well flow from an existing large geothermal field. The net power generated, 1 megawatt, will be fed into the existing power system at the demonstration site. The system will demonstrate reliable generation of inexpensive power from low temperature resources. The system will be designed for mass manufacturing and factory assembly and should cost less than $1,200/kWe installed, when manufactured in large quantities. The estimated cost of power for 300F resources is predicted to be less than 5 cents/kWh. This should enable a substantial increase in power generated from low temperature geothermal resources.

  18. Carbon dioxide exchange in three tundra sites show a dissimilar response to environmental variables

    DEFF Research Database (Denmark)

    Mbufong, Herbert Njuabe; Lund, Magnus; Christensen, Torben Røjle


    variability. An improved understanding of the control of ancillary variables on net ecosystem exchange (NEE), gross primary production (GPP) and ecosystem respiration (Re) will improve the accuracy with which CO2 exchange seasonality in Arctic tundra ecosystems is modelled. Fluxes were measured with the eddy...... Lake. Growing season NEE correlated mainly to cumulative radiation and temperature-related variables at Zackenberg, while at Daring Lake the same variables showed significant correlations with the partitioned fluxes (GPP and Re). Stordalen was temperature dependent during the growing season. This study...

  19. Exact solution of thermal radiation on vertical oscillating plate with variable temperature and mass flux

    Directory of Open Access Journals (Sweden)

    Muthucumaraswamy R.


    Full Text Available Thermal radiation effects on unsteady flow past an infinite vertical oscillating plate in the presence of variable temperature and uniform mass flux is considered. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The plate temperature is raised linearly with time and the mass is diffused from the plate to the fluid at an uniform rate. The dimensionless governing equations are solved using the Laplace transform technique. The velocity, concentration and temperature are studied for different physical parameters like the phase angle, radiation parameter, Schmidt number, thermal Grashof number, mass Grashof number and time. It is observed that the velocity increases with decreasing phase angle ωt.

  20. The interaction of thermal radiation on vertical oscillating plate with variable temperature and mass diffusion

    Directory of Open Access Journals (Sweden)

    Muthucumaraswamy R.


    Full Text Available Thermal radiation effects on unsteady free convective flow of a viscous incompressible flow past an infinite vertical oscillating plate with variable temperature and mass diffusion has been studied. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The plate temperature is raised linearly with respect to time and the concentration level near the plate is also raised linearly with respect to time. An exact solution to the dimensionless governing equations has been obtained by the Laplace transform method, when the plate is oscillating harmonically in its own plane. The effects of velocity, temperature and concentration are studied for different parameters like phase angle, radiation parameter, Schmidt number, thermal Grashof number, mass Grashof number and time are studied. It is observed that the velocity increases with decreasing phase angle ωt. .

  1. Variability in temperature, precipitation and river discharge in the Baltic States

    Energy Technology Data Exchange (ETDEWEB)

    Kriauciuniene, J.; Meilutyte-Barauskiene, D.; Sarauskiene, D. (Lithuanian Energy Inst., Kaunas (Lithuania), Lab. of Hydrology); Reihan, A. (Tallinn Univ. of Technology (Estonia), Inst. of Environmental Engineering); Koltsova, T.; Lizuma, L. (Latvian Hydrometeorological Agency, Riga (LV))


    The climate change impact on water resources is observed in all the Baltic States. These processes became more evident in the last decades. Although the territory of the Baltic States (Lithuania, Latvia, Estonia) is not large (175000 km2), the climatic differences are quite considerable. We performed a regionalization of the territory of the Baltic States depending on the conditions of river runoff formation which can be defined according to percentages of the river feeding sources (precipitation, snowmelt, groundwater). Long-term series of temperature (40 stations), precipitation (59 stations) and river discharge (77 stations) were used to compose ten regional series. This paper addresses: (1) variability in long-term regional series of temperature, precipitation and river discharge over a long period (1922-2007); (2) changes in regional series, comparing the periods 1991-2007 and 1931-1960 with the reference period (1961-1990), and (3) the impact of temperature and precipitation changes on regional river discharge. (orig.)

  2. Memory effects, two color percolation, and the temperature dependence of Mott variable-range hopping (United States)

    Agam, Oded; Aleiner, Igor L.


    There are three basic processes that determine hopping transport: (a) hopping between normally empty sites (i.e., having exponentially small occupation numbers at equilibrium), (b) hopping between normally occupied sites, and (c) transitions between normally occupied and unoccupied sites. In conventional theories all these processes are considered Markovian and the correlations of occupation numbers of different sites are believed to be small (i.e., not exponential in temperature). We show that, contrary to this belief, memory effects suppress the processes of type (c) and manifest themselves in a subleading exponential temperature dependence of the variable-range hopping conductivity. This temperature dependence originates from the property that sites of type (a) and (b) form two independent resistor networks that are weakly coupled to each other by processes of type (c). This leads to a two-color percolation problem which we solve in the critical region.

  3. Variable-temperature independently driven four-tip scanning tunneling microscope

    International Nuclear Information System (INIS)

    Hobara, Rei; Nagamura, Naoka; Hasegawa, Shuji; Matsuda, Iwao; Yamamoto, Yuko; Miyatake, Yutaka; Nagamura, Toshihiko


    The authors have developed an ultrahigh vacuum (UHV) variable-temperature four-tip scanning tunneling microscope (STM), operating from room temperature down to 7 K, combined with a scanning electron microscope (SEM). Four STM tips are mechanically and electrically independent and capable of positioning in arbitrary configurations in nanometer precision. An integrated controller system for both of the multitip STM and SEM with a single computer has also been developed, which enables the four tips to operate either for STM imaging independently and for four-point probe (4PP) conductivity measurements cooperatively. Atomic-resolution STM images of graphite were obtained simultaneously by the four tips. Conductivity measurements by 4PP method were also performed at various temperatures with the four tips in square arrangement with direct contact to the sample surface

  4. Sea surface temperature and sea ice variability in the subpolar North Atlantic from explosive volcanism of the late thirteenth century

    DEFF Research Database (Denmark)

    Sicre, M. -A.; Khodri, M.; Mignot, J.


    In this study, we use IP25 and alkenone biomarker proxies to document the subdecadal variations of sea ice and sea surface temperature in the subpolar North Atlantic induced by the decadally paced explosive tropical volcanic eruptions of the second half of the thirteenth century. The short-and long......-term evolutions of both variables were investigated by cross analysis with a simulation of the IPSL-CM5A LR model. Our results show short-term ocean cooling and sea ice expansion in response to each volcanic eruption. They also highlight that the long response time of the ocean leads to cumulative surface cooling...... and subsurface heat buildup due to sea ice capping. As volcanic forcing relaxes, the surface ocean rapidly warms, likely amplified by subsurface heat, and remains almost ice free for several decades....

  5. Precipitation response to the current ENSO variability in a warming world (United States)

    Bonfils, C.; Santer, B. D.; Phillips, T. J.; Marvel, K.; Leung, L.


    The major triggers of past and recent droughts include large modes of variability, such as ENSO, as well as specific and persistent patterns of sea surface temperature anomalies (SSTAs; Hoerling and Kumar, 2003, Shin et al. 2010, Schubert et al. 2009). However, alternative drought initiators are also anticipated in response to increasing greenhouse gases, potentially changing the relative contribution of ocean variability as drought initiator. They include the intensification of the current zonal wet-dry patterns (the thermodynamic mechanism, Held and Soden, 2006), a latitudinal redistribution of global precipitation (the dynamical mechanism, Seager et al. 2007, Seidel et al. 2008, Scheff and Frierson 2008) and a reduction of local soil moisture and precipitation recycling (the land-atmosphere argument). Our ultimate goal is to investigate whether the relative contribution of those mechanisms change over time in response to global warming. In this study, we first perform an EOF analysis of the 1900-1999 time series of observed global SST field and identify a simple ENSO-like (ENSOL) mode of SST variability. We show that this mode is well spatially and temporally correlated with observed worldwide regional precipitation and drought variability. We then develop concise metrics to examine the fidelity with which the CMIP5 coupled global climate models (CGCMs) capture this particular ENSO-like mode in the current climate, and their ability to replicate the observed teleconnections with precipitation. Based on the CMIP5 model projections of future climate change, we finally analyze the potential temporal variations in ENSOL to be anticipated under further global warming, as well as their associated teleconnections with precipitation (pattern, amplitude, and total response). Overall, our approach allows us to determine what will be the effect of the current ENSO-like variability (i.e., as measured with instrumental observations) on precipitation in a warming world. This

  6. The effect of temperature on the functional response of Phytoseiulus persimilis (Acari: Phytoseiidae). (United States)

    Skirvin, David J; Fenlon, John S


    Environmental variables, such as temperature, are important in determining the efficiency of biological control in ornamental crops. This paper examines the effect of temperature on the functional response of adult female Phytoseiulus persimilis to eggs of the spider mite, Tetranychus urticae. The functional response was determined using a new functional response assay technique with plant stems as an arena, rather than leaf discs. The use of plant stems allows the influence that plant structure has on predation to be incorporated into the assay. Control assays were also used (without predators) to estimate natural losses of prey. The data were analysed using a binomial model, with the use of Abbot's formula to correct for the losses in the controls. A combined equation to describe the effect of temperature and prey density on the predation rate of Phytoseiulus persimilis was derived. The results showed that more prey are eaten as the temperature increases from 15 degrees C to 25 degrees C, but the number of prey eaten then declines at 30 degrees C, although not to the levels seen at 20 degrees C. The implication of these results for biological control in ornamental crops, where the temperature can often exceed 30 degrees C, is discussed.

  7. Hydrologic and temperature variability at Lake Titicaca over the past 50,000 years (United States)

    Fornace, K.; Shanahan, T. M.; Sylva, S.; Ossolinski, J.; Baker, P. A.; Fritz, S. C.; Hughen, K. A.


    The Bolivian Altiplano has been the focus of many paleoclimate studies due to the important role it plays in the South American climate system. Although the timing of climate shifts in this region is relatively well known, the magnitudes of hydrologic versus temperature changes remain poorly quantified. Here we apply hydrogen isotope analysis (δD) of terrestrial leaf waxes and the TEX86 temperature proxy in sediments from Lake Titicaca to reconstruct hydrologic and temperature variability over the past 50,000 years. Our record reveals that the Altiplano underwent a major climate shift during the last deglaciation, reflected in a ~70-80% enrichment in leaf wax δD at the onset of the Holocene. Using the global isotope-temperature relationship for meteoric water, only 25-40% of this enrichment can be explained by the 4-5°C deglacial warming shown by the TEX86 proxy, indicating that precipitation was significantly reduced (and evaporation/evapotranspiration increased) during the Holocene. Further, the timing of these hydrologic and temperature changes was asynchronous during the transition from a cold and wet glacial state to a warm and dry Holocene. The major hydrologic shift recorded by leaf wax δD occurred around ~11-12 ka, consistent with Northern Hemisphere deglacial patterns, whereas TEX86 data indicate that rapid warming began much earlier, more typical of a Southern Hemisphere deglacial pattern. Within the late glacial and Holocene mean climate states, however, there is evidence of synchronous hydrologic and temperature variability on millennial timescales. This study demonstrates that climate on the Altiplano was controlled by the interaction of local and remote forcing on a range of timescales.

  8. Temperature modulates phototrophic periphyton response to chronic copper exposure

    International Nuclear Information System (INIS)

    Lambert, Anne Sophie; Dabrin, Aymeric; Morin, Soizic; Gahou, Josiane; Foulquier, Arnaud; Coquery, Marina; Pesce, Stéphane


    Streams located in vineyard areas are highly prone to metal pollution. In a context of global change, aquatic systems are generally subjected to multi-stress conditions due to multiple chemical and/or physical pressures. Among various environmental factors that modulate the ecological effects of toxicants, special attention should be paid to climate change, which is driving an increase in extreme climate events such as sharp temperature rises. In lotic ecosystems, periphyton ensures key ecological functions such as primary production and nutrient cycling. However, although the effects of metals on microbial communities are relatively well known, there is scant data on possible interactions between temperature increase and metal pollution. Here we led a study to evaluate the influence of temperature on the response of phototrophic periphyton to copper (Cu) exposure. Winter communities, collected in a 8 °C river water, were subjected for six weeks to four thermal conditions in microcosms in presence or not of Cu (nominal concentration of 15 μg L"−"1). At the initial river temperature (8 °C), our results confirmed the chronic impact of Cu on periphyton, both in terms of structure (biomass, distribution of algal groups, diatomic composition) and function (photosynthetic efficiency). At higher temperatures (13, 18 and 23 °C), Cu effects were modulated. Indeed, temperature increase reduced Cu effects on algal biomass, algal class proportions, diatom assemblage composition and photosynthetic efficiency. This reduction of Cu effects on periphyton may be related to lower bioaccumulation of Cu and/or to selection of more Cu-tolerant species at higher temperatures. - Highlights: • At in situ temperature, Cu impacted structure and activity of phototrophic biofilms. • Cu effects were reduced with increasing temperature (from +5 °C to +15 °C). • The decrease in Cu effects may be related to lower Cu bioaccumulation in biofilms. • Changes in diatom

  9. The response of the North Pacific Decadal Variability to strong tropical volcanic eruptions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tao [Chinese Academy of Sciences, Nansen-Zhu International Research Center, Institute of Atmospheric Physics, Beijing (China); Otteraa, Odd Helge [Uni Bjerknes Centre, Uni Research, Bergen (Norway); Bjerknes Center for Climate Research, Bergen (Norway); Gao, Yongqi [Chinese Academy of Sciences, Nansen-Zhu International Research Center, Institute of Atmospheric Physics, Beijing (China); Bjerknes Center for Climate Research, Bergen (Norway); Nansen Environmental and Remote Sensing Center, Bergen (Norway); Wang, Huijun [Chinese Academy of Sciences, Nansen-Zhu International Research Center, Institute of Atmospheric Physics, Beijing (China); Chinese Academy of Sciences, Climate Change Research Center, Institute of Atmospheric Physics, Beijing (China)


    In this study, the effects of volcanic forcing on North Pacific climate variability, on interannual to decadal time scales, are examined using climate model simulations covering the last 600 years. The model used is the Bergen Climate Model, a fully coupled atmosphere-ocean general circulation model. It is found that natural external forcings, such as tropical strong volcanic eruptions (SVEs) and variations in total solar irradiance, play an important role in regulating North Pacific Decadal Variability (NPDV). In response to tropical SVEs the lower stratospheric pole-to-equator temperature gradient is enhanced. The North polar vortex is strengthened, which forces a significant positive Arctic Oscillation. At the same time, dipole zonal wind anomalies associated with strong polar vortex propagate downward from the lower stratosphere. Through positive feedbacks in the troposphere, the surface westerly winds across the central North Pacific are significantly weakened, and positive sea level pressure anomalies are formed in the North Pacific. This anomalous surface circulation results in changes in the net heat fluxes and the oceanic advection across the North Pacific. As a result of this, warm water converges in the subtropical western North Pacific, where the surface waters in addition are heated by significantly reduced latent and sensible heat fluxes from the ocean. In the eastern and high-latitude North Pacific the ocean loses more heat, and large-scale decreases in sea surface temperatures are found. The overall response of this chain of events is that the North Pacific enters a negative phase of the Pacific decadal oscillation (PDO), and this negative phase of the PDO is maintained for several years. It is thus concluded that the volcanic forcing plays a key role in the phasing of the PDO. The model results furthermore highlight the important role of troposphere-stratosphere coupling, tropical-extratropical teleconnections and extratropical ocean

  10. Assessing the potential of Southern Caribbean corals for reconstructions of Holocene temperature variability

    International Nuclear Information System (INIS)

    Giry, Cyril; Felis, Thomas; Scheffers, Sander; Fensterer, Claudia


    We present a 40-year long monthly resolved Sr/Ca record from a fossil Diploria strigosa coral from Bonaire (Southern Caribbean Sea) dated with U/Th at 2.35 ka before present (BP). Secondary modifiers of this sea surface temperature (SST) proxy in annually-banded corals such as diagenetic alteration of the skeleton and skeletal growth-rate are investigated. Extensive diagenetic investigations reveal that this fossil coral skeleton is pristine which is further supported by clear annual cycles in the coral Sr/Ca record. No significant correlation between annual growth rate and Sr/Ca is observed, suggesting that the Sr/Ca record is not affected by coral growth. Therefore, we conclude that the observed interannual Sr/Ca variability was influenced by ambient SST variability. Spectral analysis of the annual mean Sr/Ca record reveals a dominant frequency centred at 6-7 years that is not associated with changes of the annual growth rate. The first monthly resolved coral Sr/Ca record from the Southern Caribbean Sea for preindustrial time suggests that fossil corals from Bonaire are suitable tools for reconstructing past SST variability. Coastal deposits on Bonaire provide abundant fossil D. strigosa colonies of Holocene age that can be accurately dated and used to reconstruct climate variability. Comparisons of long monthly resolved Sr/Ca records from multiple fossil corals will provide a mean to estimate seasonality and interannual to interdecadal SST variability of the Southern Caribbean Sea during the Holocene.

  11. A Decline in Response Variability Improves Neural Signal Detection during Auditory Task Performance. (United States)

    von Trapp, Gardiner; Buran, Bradley N; Sen, Kamal; Semple, Malcolm N; Sanes, Dan H


    The detection of a sensory stimulus arises from a significant change in neural activity, but a sensory neuron's response is rarely identical to successive presentations of the same stimulus. Large trial-to-trial variability would limit the central nervous system's ability to reliably detect a stimulus, presumably affecting perceptual performance. However, if response variability were to decrease while firing rate remained constant, then neural sensitivity could improve. Here, we asked whether engagement in an auditory detection task can modulate response variability, thereby increasing neural sensitivity. We recorded telemetrically from the core auditory cortex of gerbils, both while they engaged in an amplitude-modulation detection task and while they sat quietly listening to the identical stimuli. Using a signal detection theory framework, we found that neural sensitivity was improved during task performance, and this improvement was closely associated with a decrease in response variability. Moreover, units with the greatest change in response variability had absolute neural thresholds most closely aligned with simultaneously measured perceptual thresholds. Our findings suggest that the limitations imposed by response variability diminish during task performance, thereby improving the sensitivity of neural encoding and potentially leading to better perceptual sensitivity. The detection of a sensory stimulus arises from a significant change in neural activity. However, trial-to-trial variability of the neural response may limit perceptual performance. If the neural response to a stimulus is quite variable, then the response on a given trial could be confused with the pattern of neural activity generated when the stimulus is absent. Therefore, a neural mechanism that served to reduce response variability would allow for better stimulus detection. By recording from the cortex of freely moving animals engaged in an auditory detection task, we found that variability

  12. Streams in the urban heat island: spatial and temporal variability in temperature (United States)

    Somers, Kayleigh A.; Bernhardt, Emily S.; Grace, James B.; Hassett, Brooke A.; Sudduth, Elizabeth B.; Wang, Siyi; Urban, Dean L.


    Streams draining urban heat islands tend to be hotter than rural and forested streams at baseflow because of warmer urban air and ground temperatures, paved surfaces, and decreased riparian canopy. Urban infrastructure efficiently routes runoff over hot impervious surfaces and through storm drains directly into streams and can lead to rapid, dramatic increases in temperature. Thermal regimes affect habitat quality and biogeochemical processes, and changes can be lethal if temperatures exceed upper tolerance limits of aquatic fauna. In summer 2009, we collected continuous (10-min interval) temperature data in 60 streams spanning a range of development intensity in the Piedmont of North Carolina, USA. The 5 most urbanized streams averaged 21.1°C at baseflow, compared to 19.5°C in the 5 most forested streams. Temperatures in urban streams rose as much as 4°C during a small regional storm, whereas the same storm led to extremely small to no changes in temperature in forested streams. Over a kilometer of stream length, baseflow temperature varied by as much as 10°C in an urban stream and as little as 2°C in a forested stream. We used structural equation modeling to explore how reach- and catchment-scale attributes interact to explain maximum temperatures and magnitudes of storm-flow temperature surges. The best predictive model of baseflow temperatures (R2  =  0.461) included moderately strong pathways directly (extent of development and road density) and indirectly, as mediated by reach-scale factors (canopy closure and stream width), from catchment-scale factors. The strongest influence on storm-flow temperature surges appeared to be % development in the catchment. Reach-scale factors, such as the extent of riparian forest and stream width, had little mitigating influence (R2  =  0.448). Stream temperature is an essential, but overlooked, aspect of the urban stream syndrome and is affected by reach-scale habitat variables, catchment-scale urbanization

  13. The Diversity of Cloud Responses to Twentieth-Century Sea Surface Temperatures (United States)

    Silvers, L. G.; Paynter, D.; Zhao, M.


    Clouds play a crucial role in determining the magnitude of the global temperature response to forcing. Previous work has shown strong connections between cloud feedbacks and climate change, and between these feedbacks and changing patterns of surface temperature. We show that strong variability of the climate feedback parameter is present in three GFDL atmospheric general circulation models (AM2.1, AM3, AM4) over the twentieth century. This variability is highly correlated with the global mean cloud radiative effect (CRE) and low-cloud cover (LCC) anomalies. The decadal variability is characterized by a period of high climate sensitivity (1925-1955) and a period of low climate sensitivity (1975-2005). Observed trends of surface temperature also show distinct differences over these two periods. Although it is the SST that drives the atmospheric response, the estimated inversion strength (EIS) is necessary to reproduce the changing LCC field. During both periods, trends of EIS are shown to closely mirror trends of LCC over much of the globe, not only in the typical stratocumulus regions. Trends of the shortwave CRE (SWCRE), LCC, and the EIS are analyzed in particular geographic regions. All of these regions show a consistent relationship between LCC, SWCRE, and EIS, as well as significant differences between the two time periods. This study uses a 15 member ensemble of amip-piForcing simulations from 1870 -2005. These experiments are driven by observed SST patterns and hold greenhouse gases and other atmospheric forcing agents fixed at constant pre-industrial levels. This allows for a clean analysis of how clouds respond to changing patterns of SST and the resulting influence on the climate feedback parameter. The cloudy response of the atmosphere to changing SST patterns is critical in driving the variability of the climate feedback parameter during periods of both high and low climate sensitivity.

  14. Using Remote Sensing Mapping and Growth Response to Environmental Variability to Aide Aquatic Invasive Plant Management (United States)

    Bubenheim, David L.; Schlick, Greg; Genovese, Vanessa; Wilson, Kenneth D.


    Management of aquatic weeds in complex watersheds and river systems present many challenges to assessment, planning and implementation of management practices for floating and submerged aquatic invasive plants. The Delta Region Areawide Aquatic Weed Project (DRAAWP), a USDA sponsored area-wide project, is working to enhance planning, decision-making and operational efficiency in the California Sacramento-San Joaquin Delta. Satellite and airborne remote sensing are used map (area coverage and biomass density), direct operations, and assess management impacts on plant communities. Archived satellite records enable review of results following previous climate and management events and aide in developing long-term strategies. Examples of remote sensing aiding effectiveness of aquatic weed management will be discussed as well as areas for potential technological improvement. Modeling at local and watershed scales using the SWAT modeling tool provides insight into land-use effects on water quality (described by Zhang in same Symposium). Controlled environment growth studies have been conducted to quantify the growth response of invasive aquatic plants to water quality and other environmental factors. Environmental variability occurs across a range of time scales from long-term climate and seasonal trends to short-term water flow mediated variations. Response time for invasive species response are examined at time scales of weeks, day, and hours using a combination of study duration and growth assessment techniques to assess water quality, temperature (air and water), nitrogen, phosphorus, and light effects. These provide response parameters for plant growth models in response to the variation and interact with management and economic models associated with aquatic weed management. Plant growth models are to be informed by remote sensing and applied spatially across the Delta to balance location and type of aquatic plant, growth response to altered environments and

  15. Variability salt stress response analysis of Tunisian natural ...

    African Journals Online (AJOL)

    We evaluated the responses to salt stress of 106 Medicago truncatula lines from 11 Tunisian natural populations collected from areas that varied in soil composition, salinity and water availability. Five references lines were also included in this study. Plants were cultivated in two treatments (0 and 50 mM of NaCl) during a ...

  16. European seasonal mortality and influenza incidence due to winter temperature variability (United States)

    Rodó, X.; Ballester, J.; Robine, J. M.; Herrmann, F. R.


    Recent studies have vividly emphasized the lack of consensus on the degree of vulnerability (sensu IPCC) of European societies to current and future winter temperatures. Here we consider several climate factors, influenza incidence and daily numbers of deaths to characterize the relationship between winter temperature and mortality in a very large ensemble of European regions representing more than 400 million people. Analyses highlight the strong association between the year-to-year fluctuations in winter mean temperature and mortality, with higher seasonal cases during harsh winters, in all of the countries except the United Kingdom, the Netherlands and Belgium. This spatial distribution contrasts with the well-documented latitudinal orientation of the dependency between daily temperature and mortality within the season. A theoretical framework is proposed to reconcile the apparent contradictions between recent studies, offering an interpretation to regional differences in the vulnerability to daily, seasonal and long-term winter temperature variability. Despite the lack of a strong year-to-year association between winter mean values in some countries, it can be concluded that warmer winters will contribute to the decrease in winter mortality everywhere in Europe. More information in Ballester J, et al. (2016) Nature Climate Change 6, 927-930, doi:10.1038/NCLIMATE3070.

  17. Local Versus Remote Contributions of Soil Moisture to Near-Surface Temperature Variability (United States)

    Koster, R.; Schubert, S.; Wang, H.; Chang, Y.


    Soil moisture variations have a straightforward impact on overlying air temperatures, wetter soils can induce higher evaporative cooling of the soil and thus, locally, cooler temperatures overall. Not known, however, is the degree to which soil moisture variations can affect remote air temperatures through their impact on the atmospheric circulation. In this talk we describe a two-pronged analysis that addresses this question. In the first segment, an extensive ensemble of NASA/GSFC GEOS-5 atmospheric model simulations is analyzed statistically to isolate and quantify the contributions of various soil moisture states, both local and remote, to the variability of air temperature at a given local site. In the second segment, the relevance of the derived statistical relationships is evaluated by applying them to observations-based data. Results from the second segment suggest that the GEOS-5-based relationships do, at least to first order, hold in nature and thus may provide some skill to forecasts of air temperature at subseasonal time scales, at least in certain regions.

  18. Transformations of gold nanoparticles investigated using variable temperature high-resolution transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Young, N.P. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Huis, M.A. van; Zandbergen, H.W. [Kavli Institute of Nanoscience, Delft University of Technolgy, Lorentzweg 1, NL-2628CJ, Delft, The Netherlands. (Netherlands); Xu, H. [Department of Geology and Geophysics, and Materials Science Program, University of Wisconsin-Madison, Madison, WI (United States); Kirkland, A.I., E-mail: [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)


    Recently designed advanced in-situ specimen holders for transmission electron microscopy (TEM) have been used in studies of gold nanoparticles. We report results of variable temperature TEM experiments in which structural transformations have been correlated with specimen temperature, allowing general trends to be identified. Transformation to a decahedral morphology for particles in the size range 5-12 nm was observed for the majority of particles regardless of their initial structure. Following in-situ annealing, decahedra were found to be stable at room temperature, confirming this as the equilibrium morphology, in agreement with recently calculated phase diagrams. Other transitions at low temperature in addition to surface roughening have also been observed and correlated with the same nanoscale phase diagram. Investigations of gold particles at high temperature have revealed evidence for co-existing solid and liquid phases. Overall, these results are important in a more precise understanding of the structure and action of catalytic gold nanoparticles and in the experimental verification of theoretical calculations.

  19. Performance analysis for an irreversible variable temperature heat reservoir closed intercooled regenerated Brayton cycle

    International Nuclear Information System (INIS)

    Wang Wenhua; Chen Lingen; Sun Fengrui; Wu Chih


    In this paper, the theory of finite time thermodynamics is used in the performance analysis of an irreversible closed intercooled regenerated Brayton cycle coupled to variable temperature heat reservoirs. The analytical formulae for dimensionless power and efficiency, as functions of the total pressure ratio, the intercooling pressure ratio, the component (regenerator, intercooler, hot and cold side heat exchangers) effectivenesses, the compressor and turbine efficiencies and the thermal capacity rates of the working fluid and the heat reservoirs, the pressure recovery coefficients, the heat reservoir inlet temperature ratio, and the cooling fluid in the intercooler and the cold side heat reservoir inlet temperature ratio, are derived. The intercooling pressure ratio is optimized for optimal power and optimal efficiency, respectively. The effects of component (regenerator, intercooler and hot and cold side heat exchangers) effectivenesses, the compressor and turbine efficiencies, the pressure recovery coefficients, the heat reservoir inlet temperature ratio and the cooling fluid in the intercooler and the cold side heat reservoir inlet temperature ratio on optimal power and its corresponding intercooling pressure ratio, as well as optimal efficiency and its corresponding intercooling pressure ratio are analyzed by detailed numerical examples. When the heat transfers between the working fluid and the heat reservoirs are executed ideally, the pressure drop losses are small enough to be neglected and the thermal capacity rates of the heat reservoirs are infinite, the results of this paper replicate those obtained in recent literature

  20. CADDIS Volume 2. Sources, Stressors and Responses: Temperature (United States)

    Introduction to the temperature module, when to list temperature as a candidate cause, ways to measure temperature, simple and detailed conceptual diagrams for temperature, temperature module references and literature reviews.

  1. Impacts of variability in geomechanical properties on hydrate bearing sediment responses (United States)

    Lin, J. S.; Uchida, S.; Choi, J. H.; Seol, Y.


    Hydrate bearing sediments (HBS) may become unstable during the gas production operation, or from natural processes such as change in the landform or temperature. The geomechanical modeling is a rational way to assess HBS stability regardless of the process involved. At the present time, such modeling is laced with uncertainties. The uncertainties come from many sources that include the adequacy of a modeling framework to accurately project the response of HBS, the gap in the available field information, and the variability in the laboratory test results from limited samples. For a reasonable stability assessment, the impact of the various uncertainties have to be addressed. This study looks into one particular aspect of the uncertainty, namely, the uncertainty caused by the scatter in the laboratory tests and the ability of a constitutive model to adequately represent them. Specifically this study focuses on the scatter in the results from laboratory tests on high quality pressured core samples from a marine site, and use a critical state constitutive model to represent them. The study investigates how the HBS responses shift when the parameters of the constitutive model are varied to reflect the different aspects of experimental results. Also investigated are impacts on the responses by altering certain formulations of the constitutive model to suit particular sets of results.

  2. Upper-Level Mediterranean Oscillation index and seasonal variability of rainfall and temperature (United States)

    Redolat, Dario; Monjo, Robert; Lopez-Bustins, Joan A.; Martin-Vide, Javier


    The need for early seasonal forecasts stimulates continuous research in climate teleconnections. The large variability of the Mediterranean climate presents a greater difficulty in predicting climate anomalies. This article reviews teleconnection indices commonly used for the Mediterranean basin and explores possible extensions of one of them, the Mediterranean Oscillation index (MOi). In particular, the anomalies of the geopotential height field at 500 hPa are analyzed using segmentation of the Mediterranean basin in seven spatial windows: three at eastern and four at western. That is, different versions of an Upper-Level Mediterranean Oscillation index (ULMOi) were calculated, and monthly and annual variability of precipitation and temperature were analyzed for 53 observatories from 1951 to 2015. Best versions were selected according to the Pearson correlation, its related p value, and two measures of standardized error. The combination of the Balearic Sea and Libya/Egypt windows was the best for precipitation and temperature, respectively. The ULMOi showed the highest predictive ability in combination with the Atlantic Multidecadal Oscillation index (AMOi) for the annual temperature throughout the Mediterranean basin. The best model built from the indices presented a final mean error between 15 and 25% in annual precipitation for most of the studied area.

  3. Decreased heart rate variability responses during early postoperative mobilization

    DEFF Research Database (Denmark)

    Jans, Øivind; Brinth, Louise; Kehlet, Henrik


    in relation to postural change. METHODS: A standardized mobilization protocol before, 6 and 24 h after surgery was performed in 23 patients scheduled for elective THA. Beat-to-beat arterial blood pressure was measured by photoplethysmography and HRV was derived from pulse wave interbeat intervals and analysed......BACKGROUND: Intact orthostatic blood pressure regulation is essential for early mobilization after surgery. However, postoperative orthostatic hypotension and intolerance (OI) may delay early ambulation. The mechanisms of postoperative OI include impaired vasopressor responses relating...... and postural responses in arterial pressures decreased compared to preoperative conditions. During standing HF variation increased by 16.7 (95 % CI 8.0-25.0) normalized units (nu) at 6 h and 10.7 (2.0-19.4) nu at 24 h compared to the preoperative evaluation. At 24 h the LF/HF ratio decreased from 1.8 (1...

  4. Germination responses to current and future temperatures of four seeder shrubs across a latitudinal gradient in western Iberia. (United States)

    Chamorro, Daniel; Luna, Belén; Moreno, José M


    Species differ in their temperature germination niche. Populations of a species may similarly differ across the distribution range of the species. Anticipating the impacts of climate variability and change requires understanding the differential sensitivity to germination temperature among and within species. Here we studied the germination responses of four hard-seeded Cistaceae seeders to a range of current and future temperatures. Seeds were collected at sites across the Iberian Peninsula and exposed or not exposed to a heat shock to break dormancy, then set to germinate under four temperature regimes. Temperatures were varied daily and seasonally, simulating the temperature range across the gradient, plus an increased temperature simulating future climate. Time to germination onset and cumulative germination at the end of each season were analyzed for the effects of temperature treatments, seasons, and local climate (temperature of the germination period, T gp ) at each site. T gp was a significant covariate of germination in all species but Cistus populifolius. Temperature treatments significantly affected Cistus ladanifer, C. salviifolius, and Halimium ocymoides. Germination occurred in simulated autumn conditions, with little germination occurring at later seasons, except in unheated seeds of H. ocymoides. Exposure to a heat shock changed the sensitivity to temperature treatments and the relationships with T gp . Germination responses to temperature differ not only among species but also within species across their latitudinal range. The responses were idiosyncratic and related to the local climate of the population. This germination variability complicates generalizing the impacts of climate variability and climate change. © 2017 Botanical Society of America.

  5. Vegetation Responses to Climate Variability in the Northern Arid to Sub-Humid Zones of Sub-Saharan Africa

    Directory of Open Access Journals (Sweden)

    Khaldoun Rishmawi


    Full Text Available In water limited environments precipitation is often considered the key factor influencing vegetation growth and rates of development. However; other climate variables including temperature; humidity; the frequency and intensity of precipitation events are also known to affect productivity; either directly by changing photosynthesis and transpiration rates or indirectly by influencing water availability and plant physiology. The aim here is to quantify the spatiotemporal patterns of vegetation responses to precipitation and to additional; relevant; meteorological variables. First; an empirical; statistical analysis of the relationship between precipitation and the additional meteorological variables and a proxy of vegetation productivity (the Normalized Difference Vegetation Index; NDVI is reported and; second; a process-oriented modeling approach to explore the hydrologic and biophysical mechanisms to which the significant empirical relationships might be attributed. The analysis was conducted in Sub-Saharan Africa; between 5 and 18°N; for a 25-year period 1982–2006; and used a new quasi-daily Advanced Very High Resolution Radiometer (AVHRR dataset. The results suggest that vegetation; particularly in the wetter areas; does not always respond directly and proportionately to precipitation variation; either because of the non-linearity of soil moisture recharge in response to increases in precipitation; or because variations in temperature and humidity attenuate the vegetation responses to changes in water availability. We also find that productivity; independent of changes in total precipitation; is responsive to intra-annual precipitation variation. A significant consequence is that the degree of correlation of all the meteorological variables with productivity varies geographically; so no one formulation is adequate for the entire region. Put together; these results demonstrate that vegetation responses to meteorological variation are more

  6. Mechanisms of the atmospheric response to North Atlantic multidecadal variability: a model study

    Energy Technology Data Exchange (ETDEWEB)

    Msadek, Rym [Universite Pierre et Marie Curie-Paris 6, LOCEAN/IPSL, Paris Cedex 05 (France); Princeton University, GFDL/NOAA, AOS Program, Princeton, NJ (United States); Frankignoul, Claude [Universite Pierre et Marie Curie-Paris 6, LOCEAN/IPSL, Paris Cedex 05 (France); Li, Laurent Z.X. [Universite Pierre et Marie Curie-Paris 6, LMD/IPSL, Paris Cedex 05 (France)


    The atmospheric circulation response to decadal fluctuations of the Atlantic meridional overturning circulation (MOC) in the IPSL climate model is investigated using the associated sea surface temperature signature. A SST anomaly is prescribed in sensitivity experiments with the atmospheric component of the IPSL model coupled to a slab ocean. The prescribed SST anomaly in the North Atlantic is the surface signature of the MOC influence on the atmosphere detected in the coupled simulation. It follows a maximum of the MOC by a few years and resembles the model Atlantic multidecadal oscillation. It is mainly characterized by a warming of the North Atlantic south of Iceland, and a cooling of the Nordic Seas. There are substantial seasonal variations in the geopotential height response to the prescribed SST anomaly, with an East Atlantic Pattern-like response in summer and a North Atlantic oscillation-like signal in winter. In summer, the response of the atmosphere is global in scale, resembling the climatic impact detected in the coupled simulation, albeit with a weaker amplitude. The zonally asymmetric or eddy part of the response is characterized by a trough over warm SST associated with changes in the stationary waves. A diagnostic analysis with daily data emphasizes the role of transient-eddy forcing in shaping and maintaining the equilibrium response. We show that in response to an intensified MOC, the North Atlantic storm tracks are enhanced and shifted northward during summer, consistent with a strengthening of the westerlies. However the anomalous response is weak, which suggests a statistically significant but rather modest influence of the extratropical SST on the atmosphere. The winter response to the MOC-induced North Atlantic warming is an intensification of the subtropical jet and a southward shift of the Atlantic storm track activity, resulting in an equatorward shift of the polar jet. Although the SST anomaly is only prescribed in the Atlantic ocean

  7. Patterns of variability of the superficial temperatures of the sea in the Colombian Caribbean coast

    International Nuclear Information System (INIS)

    Bernal, Gladys; Poveda, German; Roldan, Paola; Andrade, Carlos


    The space - time variability of sea surface temperature (SST) along the Colombian coastal Caribbean zone was analyzed with monthly time series spanning the period 1982- 2000. Analyses included the spatial variability associated with the annual cycle, and inter annual time scales associated with el Nino southern oscillation (ENSO), the North Atlantic Oscillation (NAO), as well as long-term trends. Analyses were included to study two tropical low-level atmospheric jets affecting the climatology of the northwestern corner of South America (the so-called Choco and San Andres low level jets). Two separate regions have been found along the Caribbean sea to exhibit quite different climatic behavior: the southwestern region with a warm pool directly related to panama Colombia gyre, and the northeastern region with a cold pool related to the Guajira upwelling system

  8. Short-term variability of Cyg X-1 and the accretion disk temperature fluctuation

    International Nuclear Information System (INIS)

    Doi, K.


    Recent theoretical models which have been proposed to explain the observed time-averaged spectrum of Cyg X-1 assume that the hard x-rays are emitted by inverse-Compton mechanism from an optically thin, hot accretion disk around a black hole. Results are reported here of balloon observations (20-68 keV) and compared with previous rocket observations (1.5-25 keV). Using the results an analysis is made of the variability of the source intensity in the hard x-ray range which suggests that the variation is essentially spectral indicating that it originated from temperature fluctuation in an accretive disk. Such a model, which explains the stochastic nature of the variability, its characteristic time scale and spectral features at the same time in the context of the conventional accretion disk model for Cyg X-1, is examined. (U.K.)

  9. Forest ecotone response to climate change: sensitivity to temperature response functional forms

    Energy Technology Data Exchange (ETDEWEB)

    Loehle, C. [National Council for Air and Stream Improvement, Naperville, IL (United States)


    Past simulation studies have been in general agreement that climatic change could have adverse effects on forests, including geographic range shrinkages, conversion to grassland, and catastrophic forest decline or dieback. Some other recent studies, however, concluded that this agreement is generally based on parabolic temperature response rather than functional responses or data, and may therefore exaggerate dieback effects. This paper proposes a new model of temperature response that is based on a trade-off between cold tolerance and growth rate. In this model, the growth rate increases at first, and then levels off with increasing growing degree-days. Species from more southern regions have a higher minimum temperature and a faster maximum height growth rate. It is argued that faster growth rates of southern types lead to their competitive superiority in warmer environments and that such temperature response should produce less dieback and slower rates of change than the more common parabolic response model. Theoretical justification of this model is provided, followed by application of the model to a simulated ecotone under a warming scenario. Results of the study based on the proposed asymptotic model showed no dieback and only a gradual ecotone movement north, suggesting that ecotone shifts will, in fact, take many hundreds to thousands of years, with the result that species will not face the risk of extinction. 56 refs., 1 tab., 8 figs.

  10. Responses to high seawater temperatures in zooxanthellate octocorals. (United States)

    Sammarco, Paul W; Strychar, Kevin B


    Increases in Sea Surface Temperatures (SSTs) as a result of global warming have caused reef-building scleractinian corals to bleach worldwide, a result of the loss of obligate endosymbiotic zooxanthellae. Since the 1980's, bleaching severity and frequency has increased, in some cases causing mass mortality of corals. Earlier experiments have demonstrated that zooxanthellae in scleractinian corals from three families from the Great Barrier Reef, Australia (Faviidae, Poritidae, and Acroporidae) are more sensitive to heat stress than their hosts, exhibiting differential symptoms of programmed cell death - apoptosis and necrosis. Most zooxanthellar phylotypes are dying during expulsion upon release from the host. The host corals appear to be adapted or exapted to the heat increases. We attempt to determine whether this adaptation/exaptation occurs in octocorals by examining the heat-sensitivities of zooxanthellae and their host octocoral alcyonacean soft corals - Sarcophyton ehrenbergi (Alcyoniidae), Sinularia lochmodes (Alcyoniidae), and Xenia elongata (Xeniidae), species from two different families. The soft coral holobionts were subjected to experimental seawater temperatures of 28, 30, 32, 34, and 36°C for 48 hrs. Host and zooxanthellar cells were examined for viability, apoptosis, and necrosis (in hospite and expelled) using transmission electron microscopy (TEM), fluorescent microscopy (FM), and flow cytometry (FC). As experimental temperatures increased, zooxanthellae generally exhibited apoptotic and necrotic symptoms at lower temperatures than host cells and were expelled. Responses varied species-specifically. Soft coral hosts were adapted/exapted to higher seawater temperatures than their zooxanthellae. As with the scleractinians, the zooxanthellae appear to be the limiting factor for survival of the holobiont in the groups tested, in this region. These limits have now been shown to operate in six species within five families and two orders of the Cnidaria

  11. Responses to high seawater temperatures in zooxanthellate octocorals.

    Directory of Open Access Journals (Sweden)

    Paul W Sammarco

    Full Text Available Increases in Sea Surface Temperatures (SSTs as a result of global warming have caused reef-building scleractinian corals to bleach worldwide, a result of the loss of obligate endosymbiotic zooxanthellae. Since the 1980's, bleaching severity and frequency has increased, in some cases causing mass mortality of corals. Earlier experiments have demonstrated that zooxanthellae in scleractinian corals from three families from the Great Barrier Reef, Australia (Faviidae, Poritidae, and Acroporidae are more sensitive to heat stress than their hosts, exhibiting differential symptoms of programmed cell death - apoptosis and necrosis. Most zooxanthellar phylotypes are dying during expulsion upon release from the host. The host corals appear to be adapted or exapted to the heat increases. We attempt to determine whether this adaptation/exaptation occurs in octocorals by examining the heat-sensitivities of zooxanthellae and their host octocoral alcyonacean soft corals - Sarcophyton ehrenbergi (Alcyoniidae, Sinularia lochmodes (Alcyoniidae, and Xenia elongata (Xeniidae, species from two different families. The soft coral holobionts were subjected to experimental seawater temperatures of 28, 30, 32, 34, and 36°C for 48 hrs. Host and zooxanthellar cells were examined for viability, apoptosis, and necrosis (in hospite and expelled using transmission electron microscopy (TEM, fluorescent microscopy (FM, and flow cytometry (FC. As experimental temperatures increased, zooxanthellae generally exhibited apoptotic and necrotic symptoms at lower temperatures than host cells and were expelled. Responses varied species-specifically. Soft coral hosts were adapted/exapted to higher seawater temperatures than their zooxanthellae. As with the scleractinians, the zooxanthellae appear to be the limiting factor for survival of the holobiont in the groups tested, in this region. These limits have now been shown to operate in six species within five families and two orders of

  12. The high temperature impact response of tungsten and chromium (United States)

    Zaretsky, E. B.; Kanel, G. I.


    The evolution of elastic-plastic shock waves has been studied in pure polycrystalline tungsten and chromium at room and elevated temperatures over propagation distances ranging from 0.05 to 3 mm (tungsten) and from 0.1 to 2 mm (chromium). The use of fused silica windows in all but one experiment with chromium and in several high temperature experiments with tungsten led to the need for performing shock and optic characterization of these windows over the 300-1200 K temperature interval. Experiments with tungsten and chromium samples showed that annealing of the metals transforms the initial ramping elastic wave into a jump-like wave, substantially increasing the Hugoniot elastic limits of the metals. With increased annealing time, the spall strength of the two metals slightly increases. Both at room and at high temperatures, the elastic precursor in the two metals decays in two distinct regimes. At propagation distances smaller than ˜1 mm (tungsten) or ˜0.5 mm (chromium), decay is fast, with the dislocation motion and multiplication being controlled by phonon viscous drag. At greater distances, the rate of decay becomes much lower, with control of the plastic deformation being passed to the thermally activated generation and motion of dislocation double-kinks. The stress at which this transition takes place virtually coincides with the Peierls stress τP of the active glide system. Analysis of the annealing effects in both presently and previously studied BCC metals (i.e., Ta, V, Nb, Mo, W, and Cr) and of the dependencies of their normalized Peierls stresses τP(θ) /τP(0 ) on the normalized temperature θ=T /Tm allows one to conclude that the non-planar, split into several glide planes, structure of the dislocation core in these metals is mainly responsible for their plastic deformation features.

  13. Fatigue limit of Zircaloy-2 under variable one-directional tension and temperature 300 deg C

    International Nuclear Information System (INIS)

    Spasic, Z.; Simic, G.


    A vacuum chamber wad designed and constructed. It was suitable for study of materials at higher temperatures in vacuum or controlled atmospheres. Zircaloy-2 fatigue at 300 deg C in argon atmosphere was measured. Character of strain is variable one directional (A=1) tension. Obtained results are presented in tables and in the form of Veler's curve. The obtained fatigue limit was σ - 15 kp/mm 2 . The Locati method was allied as well and fatigue limit value obtained was 15,75 kp/mm 2 . Error calculated in reference to the previous value obtained by classical methods was 5% [sr

  14. Variability of temperature, evaporation, insolation and sea level pressure in East Malaysia

    International Nuclear Information System (INIS)

    Camerlengo, A.L.; Mohd Nasir Saadon; Lim You Rang; Nhakhorn Somchit; Mohd Mahatir Osman


    The interrelation between global warming and certain meteorological parameters - temperature, evaporation, sea level pressure and isolation (hours of sunshine) - in East Malaysia is addressed in this study. The inter-annual climatic variability mainly due to ENSO warm events, is also investigated. The study of the monthly distribution of both evaporation and insolation in East Malaysia (i.e., the Malaysian states of Sabah and Sarawak, both of them situated in the northern part of the island of Borneo) is also covered in this paper (author)

  15. Plastic responses to elevated temperature in low and high elevation populations of three grassland species. (United States)

    Frei, Esther R; Ghazoul, Jaboury; Pluess, Andrea R


    Local persistence of plant species in the face of climate change is largely mediated by genetic adaptation and phenotypic plasticity. In species with a wide altitudinal range, population responses to global warming are likely to differ at contrasting elevations. In controlled climate chambers, we investigated the responses of low and high elevation populations (1200 and 1800 m a.s.l.) of three nutrient-poor grassland species, Trifolium montanum, Ranunculus bulbosus, and Briza media, to ambient and elevated temperature. We measured growth-related, reproductive and phenological traits, evaluated differences in trait plasticity and examined whether trait values or plasticities were positively related to approximate fitness and thus under selection. Elevated temperature induced plastic responses in several growth-related traits of all three species. Although flowering phenology was advanced in T. montanum and R. bulbosus, number of flowers and reproductive allocation were not increased under elevated temperature. Plasticity differed between low and high elevation populations only in leaf traits of T. montanum and B. media. Some growth-related and phenological traits were under selection. Moreover, plasticities were not correlated with approximate fitness indicating selectively neutral plastic responses to elevated temperature. The observed plasticity in growth-related and phenological traits, albeit variable among species, suggests that plasticity is an important mechanism in mediating plant responses to elevated temperature. However, the capacity of species to respond to climate change through phenotypic plasticity is limited suggesting that the species additionally need evolutionary adaptation to adjust to climate change. The observed selection on several growth-related and phenological traits indicates that the study species have the potential for future evolution in the context of a warming climate.

  16. A variable-temperature scanning tunneling microscope capable of single-molecule vibrational spectroscopy

    International Nuclear Information System (INIS)

    Stipe, B.C.; Rezaei, M.A.; Ho, W.


    The design and performance of a variable-temperature scanning tunneling microscope (STM) is presented. The microscope operates from 8 to 350 K in ultrahigh vacuum. The thermally compensated STM is suspended by springs from the cold tip of a continuous flow cryostat and is completely surrounded by two radiation shields. The design allows for in situ dosing and irradiation of the sample as well as for the exchange of samples and STM tips. With the STM feedback loop off, the drift of the tip-sample spacing is approximately 0.001 Angstrom/min at 8 K. It is demonstrated that the STM is well-suited for the study of atomic-scale chemistry over a wide temperature range, for atomic-scale manipulation, and for single-molecule inelastic electron tunneling spectroscopy (IETS). copyright 1999 American Institute of Physics

  17. Characterization of polymorphic solid-state changes using variable temperature X-ray powder diffraction

    DEFF Research Database (Denmark)

    Karjalainen, Milja; Airaksinen, Sari; Rantanen, Jukka


    The aim of this study was to use variable temperature X-ray powder diffraction (VT-XRPD) to understand the solid-state changes in the pharmaceutical materials during heating. The model compounds studied were sulfathiazole, theophylline and nitrofurantoin. This study showed that the polymorph form...... of sulfathiazole SUTHAZ01 was very stable and SUTHAZ02 changed as a function of temperature to SUTHAZ01. Theophylline monohydrate changed via its metastable form to its anhydrous form during heating and nitrofurantoin monohydrate changed via amorphous form to its anhydrous form during heating. The crystallinity...... to the anhydrous form. The average crystallite size of sulfathiazole samples varied only a little during heating. The average crystallite size of both theophylline and nitrofurantoin monohydrate decreased during heating. However, the average crystallite size of nitrofurantoin monohydrate returned back to starting...

  18. Theoretical study of chemical reaction effects on vertical oscillating plate with variable temperature

    Directory of Open Access Journals (Sweden)

    Muthucumaraswamy R.


    Full Text Available An exact solution to the flow of a viscous incompressible unsteady flow past an infinite vertical oscillating plate with variable temperature and mass diffusion is presented here, taking into account of the homogeneous chemical reaction of first-order. Both the plate temperature and the concentration level near the plate are raised linearly with respect to time. The dimensionless governing equations has been obtained by the Laplace transform method, when the plate is oscillating harmonically in its own plane. The effects of velocity and concentration are studied for different parameters like phase angle, chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number and time are studied. The solutions are valid only for small values of time t. It is observed that the velocity increases with decreasing phase angle ωt or chemical reaction parameter. .

  19. Radiation effects on flow past an impulsively started vertical plate with variable temperature and mass flux

    Directory of Open Access Journals (Sweden)

    Muthucumaraswamy R.


    Full Text Available An analysis is performed to study the thermal radiation effects on unsteady free convective flow over a moving vertical plate in the presence of variable temperature and uniform mass flux. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The temperature is raised linearly with time and the concentration level near the plate are raised linearly with time. The dimensionless governing equations are solved using the Laplace transform technique. The velocity and skinfriction are studied for different parameters like the radiation parameter, Schmidt number, thermal Grashof number, mass Grashof number and time. It is observed that the velocity increases with decreasing radiation parameter.

  20. A theoretical and experimental investigation of creep problems with variable temperature

    International Nuclear Information System (INIS)

    Ponter, A.R.S.; Walter, M.H.


    This paper attempts to delineate the principal features of the behavior when load level are maintained at those appropriate to many design situations and when the temperature and loading histories are cyclic with relatively short cycle times. It is concerned with structures which accumulate creep strains of less than 1% per year and have cycle times of the order of a few days at most. In the first section the behavior of a few simple structures are investigated for spatially varying temperature fields which remain constant in time. Adopting an appropriate form of Norton's Law we show that the deformation of the structure may be related to a single reference material test conducted at a reference stress and a reference temperature, which is independent of material constants, thereby providing a generalization of the reference stress method for isothermal structures. A sequence of experiments on a simple beam structure indicates that the co-relation between structural behavior and material tests provides an acceptably accurate design method. The last section discussed a preliminary experimental investigation of a two-bar structure subject to variable temperature. It is shown that the residual stress field varies quite slowly in time and remains effectively constant after a few cycles. The theoretical consequences of the results are discussed and it is shown that constitutive relationships with differing physical assumptions can yield quite sharply contrasting deformation rates. The results of the paper show that the behavior of structures subject to a time constant temperature distribution may be related to material behavior without difficulty. When temperature and load vary with time, the more important feature of the structural behavior may be understood, although certain features of the material behavior remain ill-defined

  1. Effects of ambient temperature, humidity, and other meteorological variables on hospital admissions for angina pectoris. (United States)

    Abrignani, Maurizio G; Corrao, Salvatore; Biondo, Giovan B; Lombardo, Renzo M; Di Girolamo, Paola; Braschi, Annabella; Di Girolamo, Alberto; Novo, Salvatore


    Seasonal peaks in cardiovascular disease incidence have been widely reported, suggesting weather has a role. The aim of our study was to determine the influence of climatic variables on angina pectoris hospital admissions. We correlated the daily number of angina cases admitted to a western Sicilian hospital over a period of 12 years and local weather conditions (temperature, humidity, wind force and direction, precipitation, sunny hours and atmospheric pressure) on a day-to-day basis. A total of 2459 consecutive patients were admitted over the period 1987-1998 (1562 men, 867 women; M/F - 1:8). A seasonal variation was found with a noticeable winter peak. The results of Multivariate Poisson analysis showed a significant association between the daily number of angina hospital admission, temperature, and humidity. Significant incidence relative ratios (95% confidence intervals/measure unit) were, in males, 0.988 (0.980-0.996) (p = 0.004) for minimal temperature, 0.990 (0.984-0.996) (p = 0.001) for maximal humidity, and 1.002 (1.000-1.004) (p = 0.045) for minimal humidity. The corresponding values in females were 0.973 (0.951-0.995) (p < 0.017) for maximal temperature and 1.024 (1.001-1.048) (p = 0.037) for minimal temperature. Environmental temperature and humidity may play an important role in the pathogenesis of angina, although it seems different according to the gender. These data may help to understand the mechanisms that trigger ischemic events and to better organize hospital assistance throughout the year.

  2. Temperature-dependent behaviours are genetically variable in the nematode Caenorhabditis briggsae. (United States)

    Stegeman, Gregory W; de Mesquita, Matthew Bueno; Ryu, William S; Cutter, Asher D


    Temperature-dependent behaviours in Caenorhabditis elegans, such as thermotaxis and isothermal tracking, are complex behavioural responses that integrate sensation, foraging and learning, and have driven investigations to discover many essential genetic and neural pathways. The ease of manipulation of the Caenorhabditis model system also has encouraged its application to comparative analyses of phenotypic evolution, particularly contrasts of the classic model C. elegans with C. briggsae. And yet few studies have investigated natural genetic variation in behaviour in any nematode. Here we measure thermotaxis and isothermal tracking behaviour in genetically distinct strains of C. briggsae, further motivated by the latitudinal differentiation in C. briggsae that is associated with temperature-dependent fitness differences in this species. We demonstrate that C. briggsae performs thermotaxis and isothermal tracking largely similar to that of C. elegans, with a tendency to prefer its rearing temperature. Comparisons of these behaviours among strains reveal substantial heritable natural variation within each species that corresponds to three general patterns of behavioural response. However, intraspecific genetic differences in thermal behaviour often exceed interspecific differences. These patterns of temperature-dependent behaviour motivate further development of C. briggsae as a model system for dissecting the genetic underpinnings of complex behavioural traits.

  3. Impact of Air Temperature and SST Variability on Cholera Incidence in Southeastern Africa, 1971-2006 (United States)

    Paz, Shlomit


    The most important climatic parameter related to cholera outbreaks is the temperature, especially of the water bodies and the aquatic environment. This factor governs the survival and growth of V. cholerae, since it has a direct influence on its abundance in the environment, or alternatively, through its indirect influence on other aquatic organisms to which the pathogen is found to attach. Thus, the potential for cholera outbreaks may rise, parallel to the increase in ocean surface temperature. Indeed, recent studies indicate that global warming might create a favorable environment for V. cholerae and increase its incidence in vulnerable areas. Africa is vulnerable to climate variability. According to the recent IPCC report on Africa, the air temperature has indicated a significant warming trend since the 1960s. In recent years, most of the research into disease vectors in Africa related to climate variability has focused on malaria. The IPCC indicated that the need exists to examine the vulnerabilities and impacts of climatic factors on cholera in Africa. In light of this, the study uses a Poisson Regression Model to analyze the possible association between the cholera rates in southeastern Africa and the annual variability of air temperature and sea surface temperature (SST) at regional and hemispheric scales, for the period 1971-2006. Data description is as follows: Number of cholera cases per year in Uganda, Kenya, Rwanda, Burundi, Tanzania, Malawi, Zambia and Mozambique. Source: WHO Global Health Atlas - cholera. Seasonal and annual temperature time series: Regional scale: a) Air temperature for southeastern Africa (30° E-36° E, 5° S-17° S), source: NOAA NCEP-NCAR; b) Sea surface temperature, for the western Indian Ocean (0-20° S, 40° E-45° E), source: NOAA, Kaplan SST dataset. Hemispheric scale (for the whole Southern Hemisphere): a) Air temperature anomaly; b) Sea surface temperature anomaly. Source: CRU, University of East Anglia. The following

  4. An ultrahigh vacuum fast-scanning and variable temperature scanning tunneling microscope for large scale imaging. (United States)

    Diaconescu, Bogdan; Nenchev, Georgi; de la Figuera, Juan; Pohl, Karsten


    We describe the design and performance of a fast-scanning, variable temperature scanning tunneling microscope (STM) operating from 80 to 700 K in ultrahigh vacuum (UHV), which routinely achieves large scale atomically resolved imaging of compact metallic surfaces. An efficient in-vacuum vibration isolation and cryogenic system allows for no external vibration isolation of the UHV chamber. The design of the sample holder and STM head permits imaging of the same nanometer-size area of the sample before and after sample preparation outside the STM base. Refractory metal samples are frequently annealed up to 2000 K and their cooldown time from room temperature to 80 K is 15 min. The vertical resolution of the instrument was found to be about 2 pm at room temperature. The coarse motor design allows both translation and rotation of the scanner tube. The total scanning area is about 8 x 8 microm(2). The sample temperature can be adjusted by a few tens of degrees while scanning over the same sample area.

  5. Spatial and Seasonal Variability of Temperature in CO2 Emission from Mars' Mesosphere (United States)

    Livengood, Timothy A.; Kostiuk, Theodor; Hewagama, Tilak; Kolasinski, John R.; Henning, Wade; Fast, Kelly Elizabeth; Sonnabend, Guido; Sornig, Manuela


    We have observed non-local thermodynamic equilibrium (non-LTE) emission of carbon dioxide that probes Mars’ mesosphere in 2001, 2003, 2007, 2012, 2014, and 2016. These measurements were conducted at 10.6 μm wavelength using the Goddard Space Flight Center Heterodyne Instrument for Planetary Winds and Composition (HIPWAC) from the NASA Infrared Telescope Facility (IRTF) at resolving power (1-33)×106. The Maxwellian broadening of the emission line can be measured at this resolution, providing a direct determination of temperature in the mesosphere. The nonLTE line appears as a narrow emission core within a broad absorption formed by tropospheric CO2, which provides temperature information reaching down to the martian surface, while the mesospheric line probes temperature at about 60-80 km altitude. We will report on the spatial distribution of temperature and emission line strength with local solar time on Mars, with latitude, as well as long-term variability including seasonal effects that modify the overall thermal structure of the atmosphere. These remote measurements complement results from orbital spacecraft through access to a broad range of local solar time on each occasion.This work has been supported by the NASA Planetary Astronomy and Solar Systems Observations Programs


    Directory of Open Access Journals (Sweden)

    Maria del Rosario González-Rodriguez


    Full Text Available Consumer perception of corporate social responsibility (CSR can be directly influenced by individual value structures. This research aims to provide new knowledge regarding the relationship between basic human values and the public’s perception of CSR. It focuses on the values of higher education students and their views regarding a particular corporate social initiative. The study reveals that social, educational, and economic circumstances influence human values. Those values in turn influence why different students perceive CSR differently. These findings are relevant to companies as they provide a more detailed understanding of why certain consumer groups perceive certain CSR initiatives the way that they do. They also suggest that universities should increase their awareness of the importance of integrating human values and CSR in the curricula of future business managers and social leaders.

  7. Synthesis of Room Impulse Responses for Variable Source Characteristics

    Directory of Open Access Journals (Sweden)

    M. Kunkemoeller


    Full Text Available Every acoustic source, e.g. a speaker, a musical instrument or a loudspeaker, generally has a frequency dependent characteristic radiation pattern, which is preeminent at higher frequencies. Room acoustic measurements nowadays only account for omnidirectional source characteristics. This motivates a measurement method that is capable of obtaining room impulse responses for these specific radiation patterns by using a superposition approach of several measurements with technically well-defined sound sources. We propose a method based on measurements with a 12-channel independentlydriven dodecahedron loudspeaker array rotated by an automatically controlled turntable.Radiation patterns can be efficiently described with the use of spherical harmonics representation. We propose a method that uses this representation for the spherical loudspeaker array used for the measurements and the target radiation pattern to be used for the synthesis.We show validating results for a deterministic test sound source inside in a small lecture hall.

  8. Response of South American Ecosystems to Precipitation Variability (United States)

    Knox, R. G.; Kim, Y.; Longo, M.; Medvigy, D.; Wang, J.; Moorcroft, P. R.; Bras, R. L.


    The Ecosystem Demography Model 2 is a dynamic ecosystem model and land surface energy balance model. ED2 discretizes landscapes of particular terrain and meteorology into fractional areas of unique disturbance history. Each fraction, defined by a shared vertical soil column and canopy air space, contains a stratum of plant groups unique in functional type, size and number density. The result is a vertically distributed representation of energy transfer and plant dynamics (mortality, productivity, recruitment, disturbance, resource competition, etc) that successfully approximates the behaviour of individual-based vegetation models. In previous exercises simulating Amazonian land surface dynamics with ED 2, it was observed that when using grid averaged precipitation as an external forcing the resulting water balance typically over-estimated leaf interception and leaf evaporation while under estimating through-fall and transpiration. To investigate this result, two scenario were conducted in which land surface biophysics and ecosystem demography over the Northern portion of South America are simulated over ~200 years: (1) ED2 is forced with grid averaged values taken from the ERA40 reanalysis meteorological dataset; (2) ED2 is forced with ERA40 reanalysis, but with its precipitation re-sampled to reflect statistical qualities of point precipitation found at rain gauge stations in the region. The findings in this study suggest that the equilibrium moisture states and vegetation demography are co-dependent and show sensitivity to temporal variability in precipitation. These sensitivities will need to be accounted for in future projections of coupled climate-ecosystem changes in South America.

  9. Uniform shrub growth response to June temperature across the North Slope of Alaska (United States)

    Ackerman, Daniel E.; Griffin, Daniel; Hobbie, Sarah E.; Popham, Kelly; Jones, Erin; Finlay, Jacques C.


    The expansion of woody shrubs in arctic tundra alters many aspects of high-latitude ecosystems, including carbon cycling and wildlife habitat. Dendroecology, the study of annual growth increments in woody plants, has shown promise in revealing how climate and environmental conditions interact with shrub growth to affect these key ecosystem properties. However, a predictive understanding of how shrub growth response to climate varies across the heterogeneous landscape remains elusive. Here we use individual-based mixed effects modeling to analyze 19 624 annual growth ring measurements in the stems of Salix pulchra (Cham.), a rapidly expanding deciduous shrub. Stem samples were collected at six sites throughout the North Slope of Alaska. Sites spanned four landscapes that varied in time since glaciation and hence in soil properties, such as nutrient availability, that we expected would modulate shrub growth response to climate. Ring growth was remarkably coherent among sites and responded positively to mean June temperature. The strength of this climate response varied slightly among glacial landscapes, but in contrast to expectations, this variability was not systematically correlated with landscape age. Additionally, shrubs at all sites exhibited diminishing marginal growth gains in response to increasing temperatures, indicative of alternative growth limiting mechanisms in particularly warm years, such as temperature-induced moisture limitation. Our results reveal a regionally-coherent and robust shrub growth response to early season growing temperature, with local soil properties contributing only a minor influence on shrub growth. Our conclusions strengthen predictions of changes to wildlife habitat and improve the representation of tundra vegetation dynamics in earth systems models in response to future arctic warming.

  10. A Precise Temperature-Responsive Bistable Switch Controlling Yersinia Virulence. (United States)

    Nuss, Aaron Mischa; Schuster, Franziska; Roselius, Louisa; Klein, Johannes; Bücker, René; Herbst, Katharina; Heroven, Ann Kathrin; Pisano, Fabio; Wittmann, Christoph; Münch, Richard; Müller, Johannes; Jahn, Dieter; Dersch, Petra


    Different biomolecules have been identified in bacterial pathogens that sense changes in temperature and trigger expression of virulence programs upon host entry. However, the dynamics and quantitative outcome of this response in individual cells of a population, and how this influences pathogenicity are unknown. Here, we address these questions using a thermosensing virulence regulator of an intestinal pathogen (RovA of Yersinia pseudotuberculosis) as a model. We reveal that this regulator is part of a novel thermoresponsive bistable switch, which leads to high- and low-invasive subpopulations within a narrow temperature range. The temperature range in which bistability is observed is defined by the degradation and synthesis rate of the regulator, and is further adjustable via a nutrient-responsive regulator. The thermoresponsive switch is also characterized by a hysteretic behavior in which activation and deactivation occurred on vastly different time scales. Mathematical modeling accurately mirrored the experimental behavior and predicted that the thermoresponsiveness of this sophisticated bistable switch is mainly determined by the thermo-triggered increase of RovA proteolysis. We further observed RovA ON and OFF subpopulations of Y. pseudotuberculosis in the Peyer's patches and caecum of infected mice, and that changes in the RovA ON/OFF cell ratio reduce tissue colonization and overall virulence. This points to a bet-hedging strategy in which the thermoresponsive bistable switch plays a key role in adapting the bacteria to the fluctuating conditions encountered as they pass through the host's intestinal epithelium and suggests novel strategies for the development of antimicrobial therapies.

  11. A Precise Temperature-Responsive Bistable Switch Controlling Yersinia Virulence.

    Directory of Open Access Journals (Sweden)

    Aaron Mischa Nuss


    Full Text Available Different biomolecules have been identified in bacterial pathogens that sense changes in temperature and trigger expression of virulence programs upon host entry. However, the dynamics and quantitative outcome of this response in individual cells of a population, and how this influences pathogenicity are unknown. Here, we address these questions using a thermosensing virulence regulator of an intestinal pathogen (RovA of Yersinia pseudotuberculosis as a model. We reveal that this regulator is part of a novel thermoresponsive bistable switch, which leads to high- and low-invasive subpopulations within a narrow temperature range. The temperature range in which bistability is observed is defined by the degradation and synthesis rate of the regulator, and is further adjustable via a nutrient-responsive regulator. The thermoresponsive switch is also characterized by a hysteretic behavior in which activation and deactivation occurred on vastly different time scales. Mathematical modeling accurately mirrored the experimental behavior and predicted that the thermoresponsiveness of this sophisticated bistable switch is mainly determined by the thermo-triggered increase of RovA proteolysis. We further observed RovA ON and OFF subpopulations of Y. pseudotuberculosis in the Peyer's patches and caecum of infected mice, and that changes in the RovA ON/OFF cell ratio reduce tissue colonization and overall virulence. This points to a bet-hedging strategy in which the thermoresponsive bistable switch plays a key role in adapting the bacteria to the fluctuating conditions encountered as they pass through the host's intestinal epithelium and suggests novel strategies for the development of antimicrobial therapies.

  12. Using climate response functions in analyzing electricity production variables. A case study from Norway. (United States)

    Tøfte, Lena S.; Martino, Sara; Mo, Birger


    representation of hydropower is included and total hydro power production for each area is calculated, and the production is distributed among all available plants within each area. During simulation, the demand is affected by prices and temperatures. 6 different infrastructure scenarios of wind and power line development are analyzed. The analyses are done by running EMPS calibrated for today's situation for 11*11*8 different combinations of altered weather variables (temperature, precipitation and wind) describing different climate change scenarios, finding the climate response function for every EMPS-variable according the electricity production, such as prices and income, energy balances (supply, consumption and trade), overflow losses, probability of curtailment etc .

  13. Impacts of ozone air pollution and temperature extremes on crop yields: Spatial variability, adaptation and implications for future food security (United States)

    Tai, Amos P. K.; Val Martin, Maria


    Ozone air pollution and climate change pose major threats to global crop production, with ramifications for future food security. Previous studies of ozone and warming impacts on crops typically do not account for the strong ozone-temperature correlation when interpreting crop-ozone or crop-temperature relationships, or the spatial variability of crop-to-ozone sensitivity arising from varietal and environmental differences, leading to potential biases in their estimated crop losses. Here we develop an empirical model, called the partial derivative-linear regression (PDLR) model, to estimate the spatial variations in the sensitivities of wheat, maize and soybean yields to ozone exposures and temperature extremes in the US and Europe using a composite of multidecadal datasets, fully correcting for ozone-temperature covariation. We find generally larger and more spatially varying sensitivities of all three crops to ozone exposures than are implied by experimentally derived concentration-response functions used in most previous studies. Stronger ozone tolerance is found in regions with high ozone levels and high consumptive crop water use, reflecting the existence of spatial adaptation and effect of water constraints. The spatially varying sensitivities to temperature extremes also indicate stronger heat tolerance in crops grown in warmer regions. The spatial adaptation of crops to ozone and temperature we find can serve as a surrogate for future adaptation. Using the PDLR-derived sensitivities and 2000-2050 ozone and temperature projections by the Community Earth System Model, we estimate that future warming and unmitigated ozone pollution can combine to cause an average decline in US wheat, maize and soybean production by 13%, 43% and 28%, respectively, and a smaller decline for European crops. Aggressive ozone regulation is shown to offset such decline to various extents, especially for wheat. Our findings demonstrate the importance of considering ozone regulation

  14. Plant response to nutrient availability across variable bedrock geologies (United States)

    Castle, S.C.; Neff, J.C.


    We investigated the role of rock-derived mineral nutrient availability on the nutrient dynamics of overlying forest communities (Populus tremuloides and Picea engelmanni-Abies lasiocarpa v. arizonica) across three parent materials (andesite, limestone, and sandstone) in the southern Rocky Mountains of Colorado. Broad geochemical differences were observed between bedrock materials; however, bulk soil chemistries were remarkably similar between the three different sites. In contrast, soil nutrient pools were considerably different, particularly for P, Ca, and Mg concentrations. Despite variations in nutrient stocks and nutrient availability in soils, we observed relatively inflexible foliar concentrations and foliar stoichiometries for both deciduous and coniferous species. Foliar nutrient resorption (P and K) in the deciduous species followed patterns of nutrient content across substrate types, with higher resorption corresponding to lower bedrock concentrations. Work presented here indicates a complex plant response to available soil nutrients, wherein plant nutrient use compensates for variations in supply gradients and results in the maintenance of a narrow range in foliar stoichiometry. ?? 2008 Springer Science+Business Media, LLC.

  15. Long-Term Variability of Satellite Lake Surface Water Temperatures in the Great Lakes (United States)

    Gierach, M. M.; Matsumoto, K.; Holt, B.; McKinney, P. J.; Tokos, K.


    The Great Lakes are the largest group of freshwater lakes on Earth that approximately 37 million people depend upon for fresh drinking water, food, flood and drought mitigation, and natural resources that support industry, jobs, shipping and tourism. Recent reports have stated (e.g., the National Climate Assessment) that climate change can impact and exacerbate a range of risks to the Great Lakes, including changes in the range and distribution of certain fish species, increased invasive species and harmful algal blooms, declining beach health, and lengthened commercial navigation season. In this study, we will examine the impact of climate change on the Laurentian Great Lakes through investigation of long-term lake surface water temperatures (LSWT). We will use the ATSR Reprocessing for Climate: Lake Surface Water Temperature & Ice Cover (ARC-Lake) product over the period 1995-2012 to investigate individual and interlake variability. Specifically, we will quantify the seasonal amplitude of LSWTs, the first and last appearances of the 4°C isotherm (i.e., an important identifier of the seasonal evolution of the lakes denoting winter and summer stratification), and interpret these quantities in the context of global interannual climate variability such as ENSO.

  16. Coherence among the Northern Hemisphere land, cryosphere, and ocean responses to natural variability and anthropogenic forcing during the satellite era (United States)

    Gonsamo, Alemu; Chen, Jing M.; Shindell, Drew T.; Asner, Gregory P.


    A lack of long-term measurements across Earth's biological and physical systems has made observation-based detection and attribution of climate change impacts to anthropogenic forcing and natural variability difficult. Here we explore coherence among land, cryosphere and ocean responses to recent climate change using 3 decades (1980-2012) of observational satellite and field data throughout the Northern Hemisphere. Our results show coherent interannual variability among snow cover, spring phenology, solar radiation, Scandinavian Pattern, and North Atlantic Oscillation. The interannual variability of the atmospheric peak-to-trough CO2 amplitude is mostly impacted by temperature-mediated effects of El Niño/Southern Oscillation (ENSO) and Pacific/North American Pattern (PNA), whereas CO2 concentration is affected by Polar Pattern control on sea ice extent dynamics. This is assuming the trend in anthropogenic CO2 emission remains constant, or the interannual changes in the trends are negligible. Our analysis suggests that sea ice decline-related CO2 release may outweigh increased CO2 uptake through longer growing seasons and higher temperatures. The direct effects of variation in solar radiation and leading teleconnections, at least in part via their impacts on temperature, dominate the interannual variability of land, cryosphere and ocean indicators. Our results reveal a coherent long-term changes in multiple physical and biological systems that are consistent with anthropogenic forcing of Earth's climate and inconsistent with natural drivers.

  17. Transcriptional responses of olive flounder (Paralichthys olivaceus to low temperature.

    Directory of Open Access Journals (Sweden)

    Jinwei Hu

    Full Text Available The olive flounder (Paralichthys olivaceus is an economically important flatfish in marine aquaculture with a broad thermal tolerance ranging from 14 to 23°C. Cold-tolerant flounder that can survive during the winter season at a temperature of less than 14°C might facilitate the understanding of the mechanisms underlying the response to cold stress. In this study, the transcriptional response of flounder to cold stress (0.7±0.05°C was characterized using RNA sequencing. Transcriptome sequencing was performed using the Illumina MiSeq platform for the cold-tolerant (CT group, which survived under the cold stress; the cold-sensitive (CS group, which could barely survive at the low temperature; and control group, which was not subjected to cold treatment. In all, 29,021 unigenes were generated. Compared with the unigene expression profile of the control group, 410 unigenes were up-regulated and 255 unigenes were down-regulated in the CT group, whereas 593 unigenes were up-regulated and 289 unigenes were down-regulated in the CS group. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that signal transduction, lipid metabolism, digestive system, and signaling molecules and interaction were the most highly enriched pathways for the genes that were differentially expressed under cold stress. All these pathways could be assigned to the following four biological functions for flounder that can survive under cold stress: signal response to cold stress, cell repair/regeneration, energy production, and cell membrane construction and fluidity.

  18. Mapping surface temperature variability on a debris-covered glacier with an unmanned aerial vehicle (United States)

    Kraaijenbrink, P. D. A.; Litt, M.; Shea, J. M.; Treichler, D.; Koch, I.; Immerzeel, W.


    Debris-covered glacier tongues cover about 12% of the glacier surface in high mountain Asia and much of the melt water is generated from those glaciers. A thin layer of supraglacial debris enhances ice melt by lowering the albedo, while thicker debris insulates the ice and reduces melt. Data on debris thickness is therefore an important input for energy balance modelling of these glaciers. Thermal infrared remote sensing can be used to estimate the debris thickness by using an inverse relation between debris surface temperature and thickness. To date this has only been performed using coarse spaceborne thermal imagery, which cannot reveal small scale variation in debris thickness and its influence on the heterogeneous melt patterns on debris-covered glaciers. We deployed an unmanned aerial vehicle mounted with a thermal infrared sensor over the debris-covered Lirung Glacier in Nepal three times in May 2016 to reveal the spatial and temporal variability of surface temperature in high detail. The UAV survey matched a Landsat 8 overpass to be able to make a comparison with spaceborne thermal imagery. The UAV-acquired data is processed using Structure from Motion photogrammetry and georeferenced using DGPS-measured ground control points. Different surface types were distinguished by using data acquired by an additional optical UAV survey in order to correct for differences in surface emissivity. In situ temperature measurements and incoming solar radiation data are used to calibrate the temperature calculations. Debris thicknesses derived are validated by thickness measurements of a ground penetrating radar. Preliminary analysis reveals a spatially highly heterogeneous pattern of surface temperature over Lirung Glacier with a range in temperature of over 40 K. At dawn the debris is relatively cold and its temperature is influenced strongly by the ice underneath. Exposed to the high solar radiation at the high altitude the debris layer heats up very rapidly as sunrise

  19. Temperature-dependent, behavioural, and transcriptional variability of a tritrophic interaction consisting of bean, herbivorous mite, and predator. (United States)

    Ozawa, Rika; Nishimura, Osamu; Yazawa, Shigenobu; Muroi, Atsushi; Takabayashi, Junji; Arimura, Gen-ichiro


    Different organisms compensate for, and adapt to, environmental changes in different ways. In this way, environmental changes affect animal-plant interactions. In this study, we assessed the effect of temperature on a tritrophic system of the lima bean, the herbivorous spider mite Tetranychus urticae and the predatory mite Phytoseiulus persimilis. In this system, the plant defends itself against T. urticae by emitting volatiles that attract P. persimilis. Over 20-40 °C, the emission of volatiles by infested plants and the subsequent attraction of P. persimilis peaked at 30 °C, but the number of eggs laid by T. urticae adults and the number of eggs consumed by P. persimilis peaked at 35 °C. This indicates that the spider mites and predatory mites performed best at a higher temperature than that at which most volatile attractants were produced. Our data from transcriptome pyrosequencing of the mites found that P. persimilis up-regulated gene families for heat shock proteins (HSPs) and ubiquitin-associated proteins, whereas T. urticae did not. RNA interference-mediated gene suppression in P. persimilis revealed differences in temperature responses. Predation on T. urticae eggs by P. persimilis that had been fed PpHsp70-1 dsRNA was low at 35 °C but not at 25 °C when PpHsp70-1 expression was very high. Overall, our molecular and behavioural approaches revealed that the mode and tolerance of lima bean, T. urticae and P. persimilis are distinctly affected by temperature variability, thereby making their tritrophic interactions temperature dependent. © 2012 Blackwell Publishing Ltd.

  20. Variability in fluvial geomorphic response to anthropogenic disturbance (United States)

    Verstraeten, Gert; Broothaerts, Nils; Van Loo, Maarten; Notebaert, Bastiaan; D'Haen, Koen; Dusar, Bert; De Brue, Hanne


    Humans have greatly impacted the processes and intensities of erosion, sediment transport and storage since the introduction of agriculture. In many regions around the world, accelerated floodplain sedimentation can be related to increases in human pressure on the environment. However, the relation between the intensity of anthropogenic disturbance and the magnitude of change in fluvial sediment dynamics is not straightforward and often non-linear. Here, we review a number of case studies from contrasting environmental settings in the European loess belt, the Eastern Mediterranean mountain ranges and the eastern USA. Detailed field-based sediment archive studies and sediment budgets covering time periods ranging from 200 to over 5000 year, as well as the use of pollen and sediment provenance techniques, show that no overarching concept of changes in floodplain sedimentation following anthropogenic disturbance can be established. Slope-channel (dis)connectivity controls the existence of thresholds or tipping points that need to be crossed before significant changes in downstream sediment dynamics are recorded following human impact. This coupling can be related to characteristics of human pressure such as its duration, intensity and spatial patterns, but also to the geomorphic and tectonic setting. Furthermore, internal feedback mechanisms, such as those between erosion and soil thickness, further complicate the story. All these factors controlling the propagation of sediment from eroding hillslopes to river channels vary between regions. Hence, only unique patterns of fluvial geomorphic response can be identified. As a result, unravelling the human impact from current-day sediment archives and predicting the impact of future human disturbances on fluvial sediment dynamics remain a major challenge. This has important implications for interpreting contemporary sediment yields as well as downstream sediment records in large floodplains, deltas and the marine

  1. Modeling and simulation of control system response to temperature disturbances in a coupled heat exchangers-AHTR system

    International Nuclear Information System (INIS)

    Skavdahl, I.; Utgikar, V.P.; Christensen, R.; Sabharwall, P.; Chen, M.; Sun, X.


    Highlights: • Control architecture defined for nuclear reactor-coupled heat exchangers system. • MATLAB code developed for simulation of system response for various temperature disturbances in the system. • Control system effective in maintaining controlled variables at desired set points. • New equilibrium steady state established using controllers. • Adaptive control system capable of switching manipulated variables based on system constraints. - Abstract: An effective control strategy is essential for maintaining optimum operational efficiency of the Advanced High Temperature Reactor (AHTR)-intermediate heat exchanger (IHX)-secondary heat exchanger (SHX) system for power conversion or process heat applications. A control system design is presented in this paper for the control of the coupled intermediate and secondary heat exchangers. The cold side outlet temperature of the SHX (T_c_o) and the hot side outlet temperature of the IHX (T_h_o_2) were identified as the controlled variables that were maintained at their set points by manipulating the flow rates of heat exchange media. Transfer functions describing the relationships between the controlled variables and the manipulated and load variables were developed and the system response to various temperature disturbances was simulated using a custom-developed MATLAB program. It was found that a step disturbance of ±10 °C in the process loop changed the thermal duty by ±650 kW, equal to 6.5% of the initial duty. Similar disturbances in the primary loop had a higher impact on the system. The control system design included a provision for the switching of manipulated variables to limit the adjustment in the magnitudes of the primary manipulated variables. Simulation results indicate that the controlled variables are maintained successfully at their desired points by the control system.

  2. Modeling and simulation of control system response to temperature disturbances in a coupled heat exchangers-AHTR system

    Energy Technology Data Exchange (ETDEWEB)

    Skavdahl, I. [Department of Chemical and Materials Engineering, University of Idaho, Moscow, ID 83844 (United States); Utgikar, V.P., E-mail: [Department of Chemical and Materials Engineering, University of Idaho, Moscow, ID 83844 (United States); Christensen, R. [Nuclear Engineering Program, University of Idaho, Idaho Falls, ID 83402 (United States); Sabharwall, P. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Chen, M.; Sun, X. [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 43210 (United States)


    Highlights: • Control architecture defined for nuclear reactor-coupled heat exchangers system. • MATLAB code developed for simulation of system response for various temperature disturbances in the system. • Control system effective in maintaining controlled variables at desired set points. • New equilibrium steady state established using controllers. • Adaptive control system capable of switching manipulated variables based on system constraints. - Abstract: An effective control strategy is essential for maintaining optimum operational efficiency of the Advanced High Temperature Reactor (AHTR)-intermediate heat exchanger (IHX)-secondary heat exchanger (SHX) system for power conversion or process heat applications. A control system design is presented in this paper for the control of the coupled intermediate and secondary heat exchangers. The cold side outlet temperature of the SHX (T{sub co}) and the hot side outlet temperature of the IHX (T{sub ho2}) were identified as the controlled variables that were maintained at their set points by manipulating the flow rates of heat exchange media. Transfer functions describing the relationships between the controlled variables and the manipulated and load variables were developed and the system response to various temperature disturbances was simulated using a custom-developed MATLAB program. It was found that a step disturbance of ±10 °C in the process loop changed the thermal duty by ±650 kW, equal to 6.5% of the initial duty. Similar disturbances in the primary loop had a higher impact on the system. The control system design included a provision for the switching of manipulated variables to limit the adjustment in the magnitudes of the primary manipulated variables. Simulation results indicate that the controlled variables are maintained successfully at their desired points by the control system.

  3. Climatic variability of river outflow in the Pantanal region and the influence of sea surface temperature (United States)

    Silva, Carlos Batista; Silva, Maria Elisa Siqueira; Ambrizzi, Tércio


    This paper investigates possible linear relationships between climate, hydrology, and oceanic surface variability in the Pantanal region (in South America's central area), over interannual and interdecadal time ranges. In order to verify the mentioned relations, lagged correlation analysis and linear adjustment between river discharge at the Pantanal region and sea surface temperature were used. Composite analysis for atmospheric fields, air humidity flux divergence, and atmospheric circulation at low and high levels, for the period between 1970 and 2003, was analyzed. Results suggest that the river discharge in the Pantanal region is linearly associated with interdecadal and interannual oscillations in the Pacific and Atlantic oceans, making them good predictors to continental hydrological variables. Considering oceanic areas, 51 % of the annual discharge in the Pantanal region can be linearly explained by mean sea surface temperature (SST) in the Subtropical North Pacific, Tropical North Pacific, Extratropical South Pacific, and Extratropical North Atlantic over the period. Considering a forecast approach in seasonal scale, 66 % of the monthly discharge variance in Pantanal, 3 months ahead of SST, is explained by the oceanic variables, providing accuracy around 65 %. Annual discharge values in the Pantanal region are strongly related to the Pacific Decadal Oscillation (PDO) variability (with 52 % of linear correlation), making it possible to consider an interdecadal variability and a consequent subdivision of the whole period in three parts: 1st (1970-1977), 2nd (1978-1996), and 3rd (1997-2003) subperiods. The three subperiods coincide with distinct PDO phases: negative, positive, and negative, respectively. Convergence of humidity flux at low levels and the circulation pattern at high levels help to explain the drier and wetter subperiods. During the wetter 2nd subperiod, the air humidity convergence at low levels is much more evident than during the other two

  4. Joint spatiotemporal variability of global sea surface temperatures and global Palmer drought severity index values (United States)

    Apipattanavis, S.; McCabe, G.J.; Rajagopalan, B.; Gangopadhyay, S.


    Dominant modes of individual and joint variability in global sea surface temperatures (SST) and global Palmer drought severity index (PDSI) values for the twentieth century are identified through a multivariate frequency domain singular value decomposition. This analysis indicates that a secular trend and variability related to the El Niño–Southern Oscillation (ENSO) are the dominant modes of variance shared among the global datasets. For the SST data the secular trend corresponds to a positive trend in Indian Ocean and South Atlantic SSTs, and a negative trend in North Pacific and North Atlantic SSTs. The ENSO reconstruction shows a strong signal in the tropical Pacific, North Pacific, and Indian Ocean regions. For the PDSI data, the secular trend reconstruction shows high amplitudes over central Africa including the Sahel, whereas the regions with strong ENSO amplitudes in PDSI are the southwestern and northwestern United States, South Africa, northeastern Brazil, central Africa, the Indian subcontinent, and Australia. An additional significant frequency, multidecadal variability, is identified for the Northern Hemisphere. This multidecadal frequency appears to be related to the Atlantic multidecadal oscillation (AMO). The multidecadal frequency is statistically significant in the Northern Hemisphere SST data, but is statistically nonsignificant in the PDSI data.

  5. Amplitude variability over trials in hemodynamic responses in adolescents with ADHD

    DEFF Research Database (Denmark)

    Sørensen, L; Eichele, T; van Wageningen, H


    variable response times. In this study, we asked whether ADHD IIV in reaction time on a commonly-used test of attention might be related to variation in hemodynamic responses (HRs) observed trial-to-trial. Based on previous studies linking IIV to regions within the "default mode" network (DMN), we...... predicted that adolescents with ADHD would have higher HR variability in the DMN compared with controls, and this in turn would be related to behavioral IIV. We also explored the influence of social anxiety on HR variability in ADHD as means to test whether higher arousal associated with high trait anxiety...... would affect the neural abnormalities. We assessed single-trial variability of HRs, estimated from fMRI event-related responses elicited during an auditory oddball paradigm in adolescents with ADHD and healthy controls (11-18 years old; N = 46). Adolescents with ADHD had higher HR variability compared...

  6. Using dual response surfaces to reduce variability in launch vehicle design: A case study

    International Nuclear Information System (INIS)

    Yeniay, Ozgur; Unal, Resit; Lepsch, Roger A.


    Space transportation system conceptual design is a multidisciplinary process containing considerable element of risk. Uncertainties from one engineering discipline may propagate to another through linking parameters and the final system output may have an accumulation of risk. This may lead to significant deviations from expected performance. An estimate of variability or design risk therefore becomes essential for a robust design. This study utilizes the dual response surface approach to quantify variability in critical performance characteristics during conceptual design phase of a launch vehicle. Using design of experiments methods and disciplinary design analysis codes, dual response surfaces are constructed for the mean and standard deviation to quantify variability in vehicle weight and sizing analysis. Next, an optimum solution is sought to minimize variability subject to a constraint on mean weight. In this application, the dual response surface approach lead to quantifying and minimizing variability without much increase in design effort

  7. Study on variability of temperature and precipitation conditions in the South Eastern Bulgaria

    International Nuclear Information System (INIS)

    Koleva-Lizama, Ivanka; Lizama Rivas, Bernardo


    Freshwater resources are an essential component of the earth's hydrosphere and an indispensable part of all terrestrial ecosystems. The freshwater environment is characterized by the hydrological cycle. Global climate change and pollution could also have an impact on freshwater resources and their availability. There is now sufficient evidence, accepted by internationally respected scientists, that human activity is having an effect on the climate of the planet. The effects are mostly the result of greenhouse gas emissions, and are in addition to naturally occurring climate change. The impacts of climate change on water resources are displayed in every sector of water system. The temperature and precipitation are the most important factors, which affect on water resources. On the basis of meteorological data for more than 45 years from several gauging stations is made an analysis on the peculiarities of the climatic conditions in the southeastern Bulgaria. In order to trace the variability of historical precipitation and temperature series the analysis of trend and deviations from climate mean of recommended by WMO 'climate normal' period 1961-1990 was used. Precipitation over the southeastern Bulgaria has a significant variability over wide range of temporal and spatial scales. The annual precipitation data were examined for evidence of a secular trend by calculation of a linear best fit for the 1952 to 2000. The tendency of rainfall decrease was determined. The drought period in the studied region is noticeable during the summer. It should be concluded that temperature increase and precipitation decrease conduct to drought in the region and it may have more severe impacts on agriculture, water supply and society.(Author)

  8. Spatio-temporal variability of the North Sea cod recruitment in relation to temperature and zooplankton.

    Directory of Open Access Journals (Sweden)

    Delphine Nicolas

    Full Text Available The North Sea cod (Gadus morhua, L. stock has continuously declined over the past four decades linked with overfishing and climate change. Changes in stock structure due to overfishing have made the stock largely dependent on its recruitment success, which greatly relies on environmental conditions. Here we focus on the spatio-temporal variability of cod recruitment in an effort to detect changes during the critical early life stages. Using International Bottom Trawl Survey (IBTS data from 1974 to 2011, a major spatio-temporal change in the distribution of cod recruits was identified in the late 1990s, characterized by a pronounced decrease in the central and southeastern North Sea stock. Other minor spatial changes were also recorded in the mid-1980s and early 1990s. We tested whether the observed changes in recruits distribution could be related with direct (i.e. temperature and/or indirect (i.e. changes in the quantity and quality of zooplankton prey effects of climate variability. The analyses were based on spatially-resolved time series, i.e. sea surface temperature (SST from the Hadley Center and zooplankton records from the Continuous Plankton Recorder Survey. We showed that spring SST increase was the main driver for the most recent decrease in cod recruitment. The late 1990s were also characterized by relatively low total zooplankton biomass, particularly of energy-rich zooplankton such as the copepod Calanus finmarchicus, which have further contributed to the decline of North Sea cod recruitment. Long-term spatially-resolved observations were used to produce regional distribution models that could further be used to predict the abundance of North Sea cod recruits based on temperature and zooplankton food availability.

  9. Capturing the dynamics of response variability in the brain in ADHD

    Directory of Open Access Journals (Sweden)

    Janna van Belle


    Full Text Available ADHD is characterized by increased intra-individual variability in response times during the performance of cognitive tasks. However, little is known about developmental changes in intra-individual variability, and how these changes relate to cognitive performance. Twenty subjects with ADHD aged 7–24 years and 20 age-matched, typically developing controls participated in an fMRI-scan while they performed a go-no-go task. We fit an ex-Gaussian distribution on the response distribution to objectively separate extremely slow responses, related to lapses of attention, from variability on fast responses. We assessed developmental changes in these intra-individual variability measures, and investigated their relation to no-go performance. Results show that the ex-Gaussian measures were better predictors of no-go performance than traditional measures of reaction time. Furthermore, we found between-group differences in the change in ex-Gaussian parameters with age, and their relation to task performance: subjects with ADHD showed age-related decreases in their variability on fast responses (sigma, but not in lapses of attention (tau, whereas control subjects showed a decrease in both measures of variability. For control subjects, but not subjects with ADHD, this age-related reduction in variability was predictive of task performance. This group difference was reflected in neural activation: for typically developing subjects, the age-related decrease in intra-individual variability on fast responses (sigma predicted activity in the dorsal anterior cingulate gyrus (dACG, whereas for subjects with ADHD, activity in this region was related to improved no-go performance with age, but not to intra-individual variability. These data show that using more sophisticated measures of intra-individual variability allows the capturing of the dynamics of task performance and associated neural changes not permitted by more traditional measures.

  10. Van ‘t Hoff global analyses of variable temperature isothermal titration calorimetry data

    International Nuclear Information System (INIS)

    Freiburger, Lee A.; Auclair, Karine; Mittermaier, Anthony K.


    Highlights: ▶ We developed a global fitting strategy for ITC data collected at multiple temperatures. ▶ This method does not require prior knowledge of the binding mechanism. ▶ Monte Carlo simulations show that the approach improves the accuracy of extracted thermodynamic parameters. ▶ The method is used to study coupled folding/binding in aminoglycoside 6′-N-acetyltransferase-Ii. - Abstract: Isothermal titration calorimetry (ITC) can provide detailed information on the thermodynamics of biomolecular interactions in the form of equilibrium constants, K A , and enthalpy changes, ΔH A . A powerful application of this technique involves analyzing the temperature dependences of ITC-derived K A and ΔH A values to gain insight into thermodynamic linkage between binding and additional equilibria, such as protein folding. We recently developed a general method for global analysis of variable temperature ITC data that significantly improves the accuracy of extracted thermodynamic parameters and requires no prior knowledge of the coupled equilibria. Here we report detailed validation of this method using Monte Carlo simulations and an application to study coupled folding and binding in an aminoglycoside acetyltransferase enzyme.

  11. Discriminating low frequency components from long range persistent fluctuations in daily atmospheric temperature variability

    Directory of Open Access Journals (Sweden)

    V. Cuomo


    Full Text Available This study originated from recent results reported in literature, which support the existence of long-range (power-law persistence in atmospheric temperature fluctuations on monthly and inter-annual scales. We investigated the results of Detrended Fluctuation Analysis (DFA carried out on twenty-two historical daily time series recorded in Europe in order to evaluate the reliability of such findings in depth. More detailed inspections emphasized systematic deviations from power-law and high statistical confidence for functional form misspecification. Rigorous analyses did not support scale-free correlation as an operative concept for Climate modelling, as instead suggested in literature. In order to understand the physical implications of our results better, we designed a bivariate Markov process, parameterised on the basis of the atmospheric observational data by introducing a slow dummy variable. The time series generated by this model, analysed both in time and frequency domains, tallied with the real ones very well. They accounted for both the deceptive scaling found in literature and the correlation details enhanced by our analysis. Our results seem to evidence the presence of slow fluctuations from another climatic sub-system such as ocean, which inflates temperature variance up to several months. They advise more precise re-analyses of temperature time series before suggesting dynamical paradigms useful for Climate modelling and for the assessment of Climate Change.

  12. Effects of variable specific heat on energy transfer in a high-temperature supersonic channel flow (United States)

    Chen, Xiaoping; Li, Xiaopeng; Dou, Hua-Shu; Zhu, Zuchao


    An energy transfer mechanism in high-temperature supersonic turbulent flow for variable specific heat (VSH) condition through turbulent kinetic energy (TKE), mean kinetic energy (MKE), turbulent internal energy (TIE) and mean internal energy (MIE) is proposed. The similarities of energy budgets between VSH and constant specific heat (CSH) conditions are investigated by introducing a vibrational energy excited degree and considering the effects of fluctuating specific heat. Direct numerical simulation (DNS) of temporally evolving high-temperature supersonic turbulent channel flow is conducted at Mach number 3.0 and Reynolds number 4800 combined with a constant dimensional wall temperature 1192.60 K for VSH and CSH conditions to validate the proposed energy transfer mechanism. The differences between the terms in the two kinetic energy budgets for VSH and CSH conditions are small; however, the magnitude of molecular diffusion term for VSH condition is significantly smaller than that for CSH condition. The non-negligible energy transfer is obtained after neglecting several small terms of diffusion, dissipation and compressibility related. The non-negligible energy transfer involving TIE includes three processes, in which energy can be gained from TKE and MIE and lost to MIE. The same non-negligible energy transfer through TKE, MKE and MIE is observed for both the conditions.

  13. Nanostructures study of CNT nanofluids transport with temperature-dependent variable viscosity in a muscular tube (United States)

    Akbar, Noreen Sher; Abid, Syed Ali; Tripathi, Dharmendra; Mir, Nazir Ahmed


    The transport of single-wall carbon nanotube (CNT) nanofluids with temperature-dependent variable viscosity is analyzed by peristaltically driven flow. The main flow problem has been modeled using cylindrical coordinates and flow equations are simplified to ordinary differential equations using long wavelength and low Reynolds' number approximation. Analytical solutions have been obtained for axial velocity, pressure gradient and temperature. Results acquired are discussed graphically for better understanding. It is observed that with an increment in the Grashof number the velocity of the governing fluids starts to decrease significantly and the pressure gradient is higher for pure water as compared to single-walled carbon nanotubes due to low density. As the specific heat is very high for pure water as compared to the multi-wall carbon nanotubes, it raises temperature of the muscles, in the case of pure water, as compared to the multi-walled carbon nanotubes. Furthermore, it is noticed that the trapped bolus starts decreasing in size as the buoyancy forces are dominant as compared to viscous forces. This model may be applicable in biomedical engineering and nanotechnology to design the biomedical devices.

  14. Versatile variable temperature and magnetic field scanning probe microscope for advanced material research (United States)

    Jung, Jin-Oh; Choi, Seokhwan; Lee, Yeonghoon; Kim, Jinwoo; Son, Donghyeon; Lee, Jhinhwan


    We have built a variable temperature scanning probe microscope (SPM) that covers 4.6 K-180 K and up to 7 T whose SPM head fits in a 52 mm bore magnet. It features a temperature-controlled sample stage thermally well isolated from the SPM body in good thermal contact with the liquid helium bath. It has a 7-sample-holder storage carousel at liquid helium temperature for systematic studies using multiple samples and field emission targets intended for spin-polarized spectroscopic-imaging scanning tunneling microscopy (STM) study on samples with various compositions and doping conditions. The system is equipped with a UHV sample preparation chamber and mounted on a two-stage vibration isolation system made of a heavy concrete block and a granite table on pneumatic vibration isolators. A quartz resonator (qPlus)-based non-contact atomic force microscope (AFM) sensor is used for simultaneous STM/AFM operation for research on samples with highly insulating properties such as strongly underdoped cuprates and strongly correlated electron systems.

  15. Design Analysis of a High Temperature Radiator for the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) (United States)

    Sheth, Rubik B.; Ungar, Eugene K.; Chambliss, Joe P.; Cassady, Leonard D.


    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR), currently under development by Ad Astra Rocket Company, is a unique propulsion system that can potentially change the way space propulsion is performed. VASIMR's efficiency, when compared to that of a conventional chemical rocket, reduce propellant needed for exploration missions by a factor of 10. Currently plans include flight tests of a 200 kW VASIMR system, titled VF-200, on the International Space Station. The VF-200 will consist of two 100 kW thruster units packaged together in one engine bus. Each thruster unit has a unique heat rejection requirement of about 27 kW over a firing time of 15 minutes. In order to control rocket core temperatures, peak operating temperatures of about 300 C are expected within the thermal control loop. Design of a high temperature radiator is a unique challenge for the vehicle design. This paper will discuss the path taken to develop a steady state and transient based radiator design. The paper will describe radiator design options for the VASIMR thermal control system for use on ISS as well as future exploration vehicles.

  16. Influence of variable heat transfer coefficient of fireworks and crackers on thermal explosion critical ambient temperature and time to ignition

    Directory of Open Access Journals (Sweden)

    Guo Zerong


    Full Text Available To study the effect of variable heat transfer coefficient of fireworks and crackers on thermal explosion critical ambient temperature and time to ignition, considering the heat transfer coefficient as the power function of temperature, mathematical thermal explosion steady state and unsteady-state model of finite cylindrical fireworks and crackers with complex shell structures are established based on two-dimensional steady state thermal explosion theory. The influence of variable heat transfer coefficient on thermal explosion critical ambient temperature and time to ignition are analyzed. When heat transfer coefficient is changing with temperature and in the condition of natural convection heat transfer, critical ambient temperature lessen, thermal explosion time to ignition shorten. If ambient temperature is close to critical ambient temperature, the influence of variable heat transfer coefficient on time to ignition become large. For firework with inner barrel in example analysis, the critical ambient temperature of propellant is 463.88 K and the time to ignition is 4054.9s at 466 K, 0.26 K and 450.8s less than without considering the change of heat transfer coefficient respectively. The calculation results show that the influence of variable heat transfer coefficient on thermal explosion time to ignition is greater in this example. Therefore, the effect of variable heat transfer coefficient should be considered into thermal safety evaluation of fireworks to reduce potential safety hazard.

  17. The Variability of Neural Responses to Naturalistic Videos Change with Age and Sex. (United States)

    Petroni, Agustin; Cohen, Samantha S; Ai, Lei; Langer, Nicolas; Henin, Simon; Vanderwal, Tamara; Milham, Michael P; Parra, Lucas C


    Neural development is generally marked by an increase in the efficiency and diversity of neural processes. In a large sample ( n = 114) of human children and adults with ages ranging from 5 to 44 yr, we investigated the neural responses to naturalistic video stimuli. Videos from both real-life classroom settings and Hollywood feature films were used to probe different aspects of attention and engagement. For all stimuli, older ages were marked by more variable neural responses. Variability was assessed by the intersubject correlation of evoked electroencephalographic responses. Young males also had less-variable responses than young females. These results were replicated in an independent cohort ( n = 303). When interpreted in the context of neural maturation, we conclude that neural function becomes more variable with maturity, at least during the passive viewing of real-world stimuli.

  18. Studies of midlatitude mesospheric temperature variability and its relationship to gravity waves, tides, and planetary waves (United States)

    Beissner, Kenneth C.


    Temperature observations of the middle atmosphere have been carried out from September 1993 through July 1995 using a Rayleigh backscatter lidar located at Utah State University (42oN, 111oW). Data have been analyzed to obtain absolute temperature profiles from 40 to 90 km. Various sources of error were reviewed in order to ensure the quality of the measurements. This included conducting a detailed examination of the data reduction procedure, integration methods, and averaging techniques, eliminating errors of 1-3%. The temperature structure climatology has been compared with several other mid-latitude data sets, including those from the French lidars, the SME spacecraft, the sodium lidars at Ft. Collins and Urbana, the MSISe90 model, and a high- latitude composite set from Andenes, Norway. In general, good agreement occurs at mid-latitudes, but areas of disagreement do exist. Among these, the Utah temperatures are significantly warmer than the MSISe90 temperatures above approximately 80 km, they are lower below 80 km than any of the others in summer, they show major year- to-year variability in the winter profiles, and they differ from the sodium lidar data at the altitudes where the temperature profiles should overlap. Also, comparisons between observations and a physics based global circulation model, the TIME-GCM, were conducted for a mid-latitude site. A photo-chemical model was developed to predict airglow intensity of OH based on output from the TIME-GCM. Many discrepancies between the model and observations were found, including a modeled summer mesopause too high, a stronger summer inversion not normally observed by lidar, a fall-spring asymmetry in the OH winds and lidar temperatures but not reproduced in the TIME-GCM equinoctial periods, larger winter seasonal wind tide than observed by the FPI, and a failure of the model to reverse the summertime mesospheric jet. It is our conclusion these discrepancies are due to a gravity wave parameterization in the

  19. A Composite Likelihood Inference in Latent Variable Models for Ordinal Longitudinal Responses (United States)

    Vasdekis, Vassilis G. S.; Cagnone, Silvia; Moustaki, Irini


    The paper proposes a composite likelihood estimation approach that uses bivariate instead of multivariate marginal probabilities for ordinal longitudinal responses using a latent variable model. The model considers time-dependent latent variables and item-specific random effects to be accountable for the interdependencies of the multivariate…

  20. Processes of 30–90 days sea surface temperature variability in the northern Indian Ocean during boreal summer

    Digital Repository Service at National Institute of Oceanography (India)

    Vialard, J.; Jayakumar, A; Gnanaseelan, C.; Lengaigne, M.; Sengupta, D.; Goswami, B.N.

    Temperature (SST) signature of this atmospheric variability, using a combination of observational datasets and Ocean General Circulation Model sensitivity experiments. In addition to the previously reported intraseasonal SST signature in the Bay of Bengal...

  1. Tracer responses and control of vessels with variable flow and volume

    International Nuclear Information System (INIS)

    Niemi, A.J.


    Continuous flow vessels which are subject to variation of flow and volume are characterized by time-variable parameters. It is shown that their residence time distributions and weighting functions obtained by tracer testing are made invariant with regard to the integrated flow variables which are introduced. Under variable flow but constant volume, one such integrated variable is sufficient. Under variable volume, two different variables are suggested for the residence time distribution and weighting function, while the appropriate variable of the perfect mixer differs distinctly from that of vessels with a distinct velocity profile. It is shown through a number of example cases, that an agreement with their mathematical models is reached. The approach is extended to include also arbitrary, non-analytic response functions obtained by tracer measurements. Applications of the derived models and their incorporation in automatic control algorithms is discussed. (orig.) [de

  2. High temperature viscoplastic ratchetting: Material response or modeling artifact

    International Nuclear Information System (INIS)

    Freed, A.D.


    Ratchetting, the net accumulation of strain over a loading cycle, is a deformation mechanism that leads to distortions in shape, often resulting in a loss of function that culminates in structural failure. Viscoplastic ratchetting is prevalent at high homologous temperatures where viscous characteristics are prominent in material response. This deformation mechanism is accentuated by the presence of a mean stress; a consequence of interaction between thermal gradients and structural constraints. Favorable conditions for viscoplastic ratchetting exist in the Stirling engines being developed by the National Aeronautics and Space Administration (NASA) and the Department of Energy (DOE) for space and terrestrial power applications. To assess the potential for ratchetting and its effect on durability of high temperature structures requires a viscoplastic analysis of the design. But ratchetting is a very difficult phenomenon to accurately model. One must therefore ask whether the results from such an analysis are indicative of actual material behavior, or if they are artifacts of the theory being used in the analysis. There are several subtle aspects in a viscoplastic model that must be dealt with in order to accurately model ratchetting behavior, and therefore obtain meaningful predictions from it. In this paper, some of these subtlties and the necessary ratchet experiments needed to obtain an accurate viscoplastic representation of a material are discussed

  3. Concurrent Probabilistic Simulation of High Temperature Composite Structural Response (United States)

    Abdi, Frank


    A computational structural/material analysis and design tool which would meet industry's future demand for expedience and reduced cost is presented. This unique software 'GENOA' is dedicated to parallel and high speed analysis to perform probabilistic evaluation of high temperature composite response of aerospace systems. The development is based on detailed integration and modification of diverse fields of specialized analysis techniques and mathematical models to combine their latest innovative capabilities into a commercially viable software package. The technique is specifically designed to exploit the availability of processors to perform computationally intense probabilistic analysis assessing uncertainties in structural reliability analysis and composite micromechanics. The primary objectives which were achieved in performing the development were: (1) Utilization of the power of parallel processing and static/dynamic load balancing optimization to make the complex simulation of structure, material and processing of high temperature composite affordable; (2) Computational integration and synchronization of probabilistic mathematics, structural/material mechanics and parallel computing; (3) Implementation of an innovative multi-level domain decomposition technique to identify the inherent parallelism, and increasing convergence rates through high- and low-level processor assignment; (4) Creating the framework for Portable Paralleled architecture for the machine independent Multi Instruction Multi Data, (MIMD), Single Instruction Multi Data (SIMD), hybrid and distributed workstation type of computers; and (5) Market evaluation. The results of Phase-2 effort provides a good basis for continuation and warrants Phase-3 government, and industry partnership.

  4. Simulation of spatio-temporal variability of temperature in the Taganrog Bay with MITgcm model

    Directory of Open Access Journals (Sweden)

    Zaporozhtsev I. F.


    Full Text Available The goal of the paper is to analyze efficiency of MITgcm in simulation of temperature fields' variability in the Taganrog Bay. Authors are the first to consider hydrodynamic modeling approach based on MITgcm for this bay. In situ temperature values to be compared with the model data have been obtained during two Murmansk Marine Biological Institute Kola Scientific Center RAS and Southern Scientific Center RAS coupled expeditions in summer and autumn of 2005. The step of calculation grid is agreed with the step of direct measurements stations grid. The obtained during cruises temperature and salinity data cover the Taganrog Bay with 2' latitude and 3' longitude steps (and with 4' latitude and 6' longitude steps correspondingly for thermohaline homogeneous areas. Depth step is 0.5 m. Data for initialization and atmospheric forcing have been taken from public reanalysis databases and atlases, datasets limitations are discussed. To simplify boundary conditions simulation has been carried out for the whole Azov Sea. Numerical experiments series has been fulfilled to determine the optimal start date of simulation and initial constant temperature field. In view of significant experiment time cost optimization task has been solved for restricted parameters values set and with doubled grid steps (4' latitude and 6' longitude steps. The determined values have been used to solve original task of model data verification with the measured ones. As far as the results obtained by the authors with the particular workstation PC are concerned, the conclusion about possibility of MITgcm simulation in real areas without specialized highperformance computers has been given.

  5. Seasonal and inter-annual temperature variability in the bottom waters over the Black Sea shelf (United States)

    Shapiro, G. I.; Wobus, F.; Aleynik, D. L.


    convection events is well preserved over the following months in the deep sea, the signal of winter cooling in the Bottom Shelf Waters significantly reduces during the warm season. The time series of temperature in the BSW is highly correlated with the temperature of Cold Intermediate Waters in the deep sea thus indicating that the isopycnal exchanges with the deep sea are more important for inter-annual/inter-decadal variability of the BSW on the Western Black Sea shelf than winter convection on the shelf itself.

  6. Response of ferritic steels to nonsteady loading at elevated temperatures

    International Nuclear Information System (INIS)

    Swindeman, R.W.


    High-temperature operating experience is lacking in pressure vessel materials that have strength levels above 586 MPa. Because of their tendency toward strain softening, we have been concerned about their behavior under nonsteady loading. Testing was undertaken to explore the extent of softening produced by monotonic and cyclic strains. The specific materials included bainitic 2 1/4Cr-1Mo steel, a micro-alloyed version of 2 1/4Cr-1Mo steel, a micro-alloyed version of 2 1/4Cr-1Mo steel containing vanadium, titanium, and boron, and a martensitic 9Cr-1Mo-V-Nb steel. Tests included tensile, creep, variable stress creep, relaxation, strain cycling, stress cycling, and non-isothermal creep ratchetting experiments. We found that these steels had very low uniform elongation and exhibited small strains to the onset of tertiary creep compared to annealed 2 1/4Cr-1Mo steel. Repeated relaxation test data also indicated a limited capacity for strain hardening. Reversal strains produced softening. The degree of softening increased with increased initial strength level. We concluded that the high strength bainitic and martensitic steels should perform well when used under conditions where severe cyclic operation does not occur

  7. Using Streamflow and Stream Temperature to Assess the Potential Responses of Freshwater Fish to Climate Change (United States)

    VanCompernolle, M.; Ficklin, D. L.; Knouft, J.


    Streamflow and stream temperature are key variables influencing growth, reproduction, and mortality of freshwater fish. Climate-induced changes in these variables are expected to alter the structure and function of aquatic ecosystems. Using Maxent, a species distribution model (SDM) based on the principal of maximum entropy, we predicted potential distributional responses of 100 fish species in the Mobile River Basin (MRB) to changes in climate based on contemporary and future streamflow and stream temperature estimates. Geologic, topographic, and landcover data were also included in each SDM to determine the contribution of these physical variables in defining areas of suitable habitat for each species. Using an ensemble of Global Climate Model (GCM) projections under a high emissions scenario, predicted distributions for each species across the MRB were produced for both a historical time period, 1975-1994, and a future time period, 2060-2079, and changes in total area and the percent change in historical suitable habitat for each species were calculated. Results indicate that flow (28%), temperature (29%), and geology (29%), on average, contribute evenly to determining areas of suitable habitat for fish species in the MRB, with landcover and slope playing more limited roles. Temperature contributed slightly more predictive ability to SDMs (31%) for the 77 species experiencing overall declines in areas of suitable habitat, but only 21% for the 23 species gaining habitat across all GCMs. Species are expected to lose between 15-24% of their historical suitable habitat, with threatened and endangered species losing 22-30% and those endemic to the MRB losing 19-28%. Sculpins (Cottidae) are expected to lose the largest amount of historical habitat (up to 84%), while pygmy sunfish (Elassomatidae) are expected to lose less than 1% of historical habitat. Understanding which species may be at risk of habitat loss under future projections of climate change can help

  8. Probing Gas Adsorption in Zeolites by Variable-Temperature IR Spectroscopy: An Overview of Current Research. (United States)

    Garrone, Edoardo; Delgado, Montserrat R; Bonelli, Barbara; Arean, Carlos O


    The current state of the art in the application of variable-temperature IR (VTIR) spectroscopy to the study of (i) adsorption sites in zeolites, including dual cation sites; (ii) the structure of adsorption complexes and (iii) gas-solid interaction energy is reviewed. The main focus is placed on the potential use of zeolites for gas separation, purification and transport, but possible extension to the field of heterogeneous catalysis is also envisaged. A critical comparison with classical IR spectroscopy and adsorption calorimetry shows that the main merits of VTIR spectroscopy are (i) its ability to provide simultaneously the spectroscopic signature of the adsorption complex and the standard enthalpy change involved in the adsorption process; and (ii) the enhanced potential of VTIR to be site specific in favorable cases.

  9. Surface Variability of Short-wavelength Radiation and Temperature on Exoplanets around M Dwarfs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xin; Tian, Feng [Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing 100084 (China); Wang, Yuwei [Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, QC H3A 0B9 (Canada); Dudhia, Jimy; Chen, Ming, E-mail: [National Center for Atmospheric Research, Boulder, CO (United States)


    It is a common practice to use 3D General Circulation Models (GCM) with spatial resolution of a few hundred kilometers to simulate the climate of Earth-like exoplanets. The enhanced albedo effect of clouds is especially important for exoplanets in the habitable zones around M dwarfs that likely have fixed substellar regions and substantial cloud coverage. Here, we carry out mesoscale model simulations with 3 km spatial resolution driven by the initial and boundary conditions in a 3D GCM and find that it could significantly underestimate the spatial variability of both the incident short-wavelength radiation and the temperature at planet surface. Our findings suggest that mesoscale models with cloud-resolving capability be considered for future studies of exoplanet climate.

  10. Changes in the interannual variability of the tropical Pacific as a response to an equatorial Atlantic forcing

    Directory of Open Access Journals (Sweden)

    Marta Martín-Rey


    Full Text Available Previous studies have reported that the tropical Atlantic has had an influence on tropical Pacific interannual variability since the 1970s. This variability is studied in the present work, using simulations from a coupled model in the Indo-Pacific but with observed sea surface temperature (SST prescribed over the Atlantic. The interannual variability is compared with that from a control simulation in which climatological SSTs are prescribed over the Atlantic. Differences in the Pacific mean state and in its variability are found in the forced simulation as a response to a warming in the equatorial Atlantic, characterized by a cooler background state and an increase in the variability over the tropical Pacific. A striking result is that the principal modes of tropical Pacific SST interannual variability show significant differences before and after the 1970s, providing new evidence of the Atlantic influence on the Pacific Ocean. Significant cooling (warming in the equatorial Atlantic could have caused anomalous winds in the central-easter Pacific during the summer since 1970s. The thermocline depth also seems to be altered, triggering the dynamical processes involved in the development of El Niño (La Niña phenomenon in the following winter. An increase in frequency of Niño and Niña events favouring the Central Pacific (CP ones is observed in the last three decades. Further analyses using coupled models are still necessary to help us to understand the causes of this inter-basin connection.

  11. Within-person variability in response speed as an indicator of cognitive impairment in older adults. (United States)

    Strauss, Esther; Bielak, Allison A M; Bunce, David; Hunter, Michael A; Hultsch, David F


    Within-person variability may be an important indicator of central nervous system compromise. In this study, within-person variability in response speed was examined in community-dwelling older adults, ages 64-92 years, using a new framework that takes into account both the extent (single versus multiple domains affected) and nature (amnestic versus non-amnestic) of the cognitive impairment. Those with multiple domains of impairment were more variable than those who showed an isolated area of impairment, regardless of whether memory was one of the domains affected. Further, for those with difficulties in two or more non-memory domains, increased variability was most evident in more cognitively demanding situations, when individuals had to manipulate information held briefly in mind, switch cognitive set or inhibit an automatic response. Finally, group differentiation was better achieved when within-person variability as opposed to mean speed of performance was considered.

  12. Trends and variability of daily temperature extremes during 1960-2012 in the Yangtze River Basin, China (United States)

    The variability of temperature extremes has been the focus of attention during the past few decades, and may exert a great influence on the global hydrologic cycle and energy balance through thermal forcing. Based on daily minimum and maximum temperature observed by the China Meteorological Administ...

  13. Elevated temperature inelastic analysis of metallic media under time varying loads using state variable theories

    International Nuclear Information System (INIS)

    Kumar, V.; Mukherjee, S.


    In the present paper a general time-dependent inelastic analysis procedure for three-dimensional bodies subjected to arbitrary time varying mechanical and thermal loads using these state variable theories is presented. For the purpose of illustrations, the problems of hollow spheres, cylinders and solid circular shafts subjected to various combinations of internal and external pressures, axial force (or constraint) and torque are analyzed using the proposed solution procedure. Various cyclic thermal and mechanical loading histories with rectangular or sawtooth type waves with or without hold-time are considered. Numerical results for these geometrical shapes for various such loading histories are presented using Hart's theory (Journal of Engineering Materials and Technology 1976). The calculations are performed for nickel in the temperature range of 25 0 C to 400 0 C. For integrating forward in time, a method of solving a stiff system of ordinary differential equations is employed which corrects the step size and order of the method automatically. The limit loads for hollow spheres and cylinders are calculated using the proposed method and Hart's theory, and comparisons are made against the known theoretical results. The numerical results for other loading histories are discussed in the context of Hart's state variable type constitutive relations. The significance of phenomena such as strain rate sensitivity, Bauschinger's effect, crep recovery, history dependence and material softening with regard to these multiaxial problems are discussed in the context of Hart's theory

  14. Development of a temperature-variable magnetic resonance imaging system using a 1.0T yokeless permanent magnet. (United States)

    Terada, Y; Tamada, D; Kose, K


    A temperature variable magnetic resonance imaging (MRI) system has been developed using a 1.0 T permanent magnet. A permanent magnet, gradient coils, radiofrequency coil, and shim coil were installed in a temperature variable thermostatic bath. First, the variation in the magnetic field inhomogeneity with temperature was measured. The inhomogeneity has a specific spatial symmetry, which scales linearly with temperature, and a single-channel shim coil was designed to compensate for the inhomogeneity. The inhomogeneity was drastically reduced by shimming over a wide range of temperature from -5°C to 45°C. MR images of an okra pod acquired at different temperatures demonstrated the high potential of the system for visualizing thermally sensitive properties. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Seasonal Variability of Saturn's Tropospheric Temperatures, Winds and Para-H2 from Cassini Far-IR Spectroscopy (United States)

    Fletcher, Leigh N.; Irwin, P. G. J; Achterberg, R. K.; Orton, G. S.; Flasar, F. M.


    Far-IR 16-1000 micrometer spectra of Saturn's hydrogen-helium continuum measured by Cassini's Composite Infrared Spectrometer (CIRS) are inverted to construct a near-continuous record of upper tropospheric (70-700 mbar) temperatures and para-H2 fraction as a function of latitude, pressure and time for a third of a saturnian year (2004-2014, from northern winter to northern spring). The thermal field reveals evidence of reversing summertime asymmetries superimposed onto the belt/zone structure. The temperature structure is almost symmetric about the equator by 2014, with seasonal lag times that increase with depth and are qualitatively consistent with radiative climate models. Localised heating of the tropospheric hazes (100-250 mbar) create a distinct perturbation to the temperature profile that shifts in magnitude and location, declining in the autumn hemisphere and growing in the spring. Changes in the para-H2 (f(sub p)) distribution are subtle, with a 0.02-0.03 rise over the spring hemisphere (200-500 mbar) perturbed by (i) low-f(sub p) air advected by both the springtime storm of 2010 and equatorial upwelling; and (ii) subsidence of high-f(sub p) air at northern high latitudes, responsible for a developing north-south asymmetry in f(sub p). Conversely, the shifting asymmetry in the para-H2 disequilibrium primarily reflects the changing temperature structure (and hence the equilibrium distribution of f(sub p)), rather than actual changes in f(sub p) induced by chemical conversion or transport. CIRS results interpolated to the same point in the seasonal cycle as re-analysed Voyager-1 observations (early northern spring) show qualitative consistency from year to year (i.e., the same tropospheric asymmetries in temperature and f(sub p)), with the exception of the tropical tropopause near the equatorial zones and belts, where downward propagation of a cool temperature anomaly associated with Saturn's stratospheric oscillation could potentially perturb tropopause

  16. Study on Short-term Variability of Ship Responses in Waves

    DEFF Research Database (Denmark)

    Nielsen, Ulrik Dam; Iseki, Toshio


    Short-term variability of ship responses is investigated by cross-spectrum analysis. In a steady state condition, it is well known that a certain length of sampled data is required for stable results of the spectral analysis. However, the phase lag between responses, in terms of the phase angle o...

  17. Characterisation of micro and nano SQUIDs at variable temperature and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Koehn, Claudia; Storm, Jan-Hendrik; Bechstein, Sylke; Schurig, Thomas [Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin (Germany)


    SQUIDs are highly suited to investigate the magnetic properties of samples with small dimensions, such as nanoparticles, or to read out nanoelectromechanical systems (NEMS). Due to the small sample size, SQUIDs with dimensions in the μm or nm regime are desirable. These micro or nano SQUIDs should have a low noise and no hysteresis in the current-voltage-characteristic, even when operated in high magnetic fields of up to several 100 mT. To investigate such SQUID, we developed measurement setups which can simulate the measurement conditions of the intended SQUID application. The design and performance of two measurement setups will be shown and compared. One setup uses a dipstick that is immersed in liquid helium and can be evacuated to provide SQUID temperatures between 4.5 K and 10 K. The other one uses an evaporation cryostat so that the temperature can be varied from 2 K to 60 K. Both setups are equipped with coils to enable SQUID operation in variable magnetic field. To minimize noise, the output of the SQUID under test is preamplified by a SQUID series array which is operated at 4.2 K. First results of the characterisation of micro and nano SQUIDs will be presented.

  18. Hybrid Vibration Control under Broadband Excitation and Variable Temperature Using Viscoelastic Neutralizer and Adaptive Feedforward Approach

    Directory of Open Access Journals (Sweden)

    João C. O. Marra


    Full Text Available Vibratory phenomena have always surrounded human life. The need for more knowledge and domain of such phenomena increases more and more, especially in the modern society where the human-machine integration becomes closer day after day. In that context, this work deals with the development and practical implementation of a hybrid (passive-active/adaptive vibration control system over a metallic beam excited by a broadband signal and under variable temperature, between 5 and 35°C. Since temperature variations affect directly and considerably the performance of the passive control system, composed of a viscoelastic dynamic vibration neutralizer (also called a viscoelastic dynamic vibration absorber, the associative strategy of using an active-adaptive vibration control system (based on a feedforward approach with the use of the FXLMS algorithm working together with the passive one has shown to be a good option to compensate the neutralizer loss of performance and generally maintain the extended overall level of vibration control. As an additional gain, the association of both vibration control systems (passive and active-adaptive has improved the attenuation of vibration levels. Some key steps matured over years of research on this experimental setup are presented in this paper.

  19. Mg/Ca Ratios in Coralline Red Algae as Temperature Proxies for Reconstructing Labrador Current Variability (United States)

    Gamboa, G.; Hetzinger, S.; Halfar, J.; Zack, T.; Kunz, B.; Adey, W.


    Marine ecosystems and fishery productivity in the Northwestern Atlantic have been considerably affected by regional climate and oceanographic changes. Fluctuations of North Atlantic marine climate have been linked in part to a dominant pattern of atmospheric circulation known as the North Atlantic Oscillation, which has a strong influence on transport variability of the Labrador Current (LC). The cold LC originates in the Labrador Sea and flows southbound along the Eastern Canadian coastline causing an important cooling effect on marine waters off the Canadian Atlantic provinces. Although interdecadal and interannual variability of sea surface temperatures (SST) in the LC system have been documented, a long-term pattern has not been identified. In order to better understand the observed ecosystem changes and their relationship with climate variability in the Northwestern Atlantic, a century-scale reconstruction of spatial and temporal variations of the LC is needed. This, however, requires reliable long-term and high-resolution SST records, which are not available from short instrumental observations. Here we present the first century-scale SST reconstructions from the Northwest Atlantic using long-lived coralline red algae. Coralline red algae have a high-Mg calcite skeleton, live in shallow water worldwide and develop annual growth bands. It has previously been demonstrated that subannual resolution SSTs can be obtained from coralline red algal Mg/Ca ratios, a commonly used paleotemperature proxy. Specimens of the long-lived coralline red algae Clathromorphum compactum were collected alive in August 2008 along a latitudinal transect spanning the southern extent of LC flow in Nova Scotia and Newfoundland. This collection is supplemented with specimens from the same region collected in the 1960's. In order to reconstruct spatial and temporal patterns of the LC, selected samples of C. compactum were analyzed for Mg/Ca using Laser Ablation Inductively-Coupled Plasma

  20. A broadband variable-temperature test system for complex permittivity measurements of solid and powder materials (United States)

    Zhang, Yunpeng; Li, En; Zhang, Jing; Yu, Chengyong; Zheng, Hu; Guo, Gaofeng


    A microwave test system to measure the complex permittivity of solid and powder materials as a function of temperature has been developed. The system is based on a TM0n0 multi-mode cylindrical cavity with a slotting structure, which provides purer test modes compared to a traditional cavity. To ensure the safety, effectiveness, and longevity, heating and testing are carried out separately and the sample can move between two functional areas through an Alundum tube. Induction heating and a pneumatic platform are employed to, respectively, shorten the heating and cooling time of the sample. The single trigger function of the vector network analyzer is added to test software to suppress the drift of the resonance peak during testing. Complex permittivity is calculated by the rigorous field theoretical solution considering multilayer media loading. The variation of the cavity equivalent radius caused by the sample insertion holes is discussed in detail, and its influence to the test result is analyzed. The calibration method for the complex permittivity of the Alundum tube and quartz vial (for loading powder sample), which vary with the temperature, is given. The feasibility of the system has been verified by measuring different samples in a wide range of relative permittivity and loss tangent, and variable-temperature test results of fused quartz and SiO2 powder up to 1500 °C are compared with published data. The results indicate that the presented system is reliable and accurate. The stability of the system is verified by repeated and long-term tests, and error analysis is presented to estimate the error incurred due to the uncertainties in different error sources.

  1. Temperature variability over the past millennium inferred from Northwestern Alaska tree rings

    Energy Technology Data Exchange (ETDEWEB)

    D' Arrigo, Rosanne; Mashig, Erika; Jacoby, Gordon [Lamont-Doherty Earth Observatory, Tree-Ring Laboratory, Palisades, NY (United States); Frank, David [WSL, Birmensdorf (Switzerland); Wilson, Rob [University of Edinburgh, School of Geosciences, Grant Institute, Edinburgh (United Kingdom)


    We describe a new tree-ring width data set of 14 white spruce chronologies for the Seward Peninsula (SP), Alaska, based on living and subfossil wood dating from 1358 to 2001 AD. A composite chronology derived from these data correlates positively and significantly with summer temperatures at Nome from 1910 to 1970, after which there is some loss of positive temperature response. There is inferred cooling during periods within the Little Ice Age (LIA) from the early to middle 1600s and late 1700s to middle 1800s; and warming from the middle 1600s to early 1700s. We also present a larger composite data set covering 978-2001 AD, utilizing the SP ring-width data in combination with archaeological wood measurements and other recent collections from northwestern Alaska. The Regional Curve Standardization (RCS) method was employed to maximize potential low-frequency information in this data set. The RCS chronology shows intervals of persistent above-average growth around the time of the Medieval Warm Period (MWP) early in the millennium, which are comparable to growth levels in recent centuries. There is a more sustained cold interval during the LIA inferred from the RCS record as compared to the SP ring-width series. The chronologies correlate significantly with Bering and Chukchi Sea sea surface temperatures and with the Pacific Decadal Oscillation index. These atmosphere-ocean linkages probably account for the differences between these records and large-scale reconstructions of Arctic and Northern Hemisphere temperatures based largely on continental interior proxy data. (orig.)

  2. Physiological responses in a variable environment: relationships between metabolism, hsp and thermotolerance in an intertidal-subtidal species.

    Directory of Open Access Journals (Sweden)

    Yun-wei Dong

    Full Text Available Physiological responses to temperature reflect the evolutionary adaptations of organisms to their thermal environment and the capability of animals to tolerate thermal stress. Contrary to conventional metabolism theory, increasing environmental temperatures have been shown to reduce metabolic rate in rocky-eulittoral-fringe species inhabiting highly variable environments, possibly as a strategy for energy conservation. To study the physiological adaptations of an intertidal-subtidal species to the extreme and unpredictable heat stress of the intertidal zone, oxygen consumption rate and heat shock protein expression were quantified in the sea cucumber Apostichopus japonicus. Using simulate natural temperatures, the relationship between temperature, physiological performance (oxygen consumption and heat shock proteins and thermotolerance were assessed. Depression of oxygen consumption rate and upregulation of heat shock protein genes (hsps occurred in sequence when ambient temperature was increased from 24 to 30°C. Large-scale mortality of the sea cucumber occurred when temperatures rose beyond 30°C, suggesting that the upregulation of heat shock proteins and mortality are closely related to the depression of aerobic metabolism, a phenomenon that is in line with the concept of oxygen- and capacity-limited thermal tolerance (OCLTT. The physiologically-related thermotolerance of this sea cucumber should be an adaptation to its local environment.

  3. CADDIS Volume 2. Sources, Stressors and Responses: Urbanization - Temperature (United States)

    water temperature changes associated with urbanization, heated surface runoff associated with urbanization, how temperature changes associated with urbanization can affect stream biota, interactive effects of urbanizaiton and climate change.

  4. Application of polymeric macroporous supports for temperature-responsive chromatography of pharmaceuticals. (United States)

    Lamprou, Alexandros; Gavriilidou, Agni-Faviola-Mika; Storti, Giuseppe; Soos, Miroslav; Morbidelli, Massimo


    A macroporous particulate support prepared previously by reactive gelation under shear and functionalized with poly(N-isopropylacrylamide), PNIPAM, brushes of variable length is applied for temperature-responsive chromatography, whereby temperature modulates hydrophobic interactions. Several different analytes, including small pharmaceuticals, peptides, proteins and monoclonal antibodies are employed. Contrary to the most commonly observed behavior in conventional chromatography, increasing retention is observed at elevated temperatures. Peak broadening is quantified using the peak standard deviation, which depends on both the polymer chain conformation and analyte adsorptivity. The favorable effect of grafted polymer thickness on retention becomes progressively less pronounced for thicker grafted PNIPAM layers. The effect of eluent composition on solute-sorbent interactions was investigated by introducing NaCl, methanol, dioxane and by varying the pH. Salt or organic solvent addition affects apart from the analytes solution properties, the hydrophobicity of the stationary phase itself. Frontal analyses performed at different temperatures to determine dynamic binding capacities, indicate small mass transfer resistances imposed by this novel packing material. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Temperature control of molecular circuit switch responsible for virulent phenotype expression in uropathogenic Escherichia coli (United States)

    Samoilov, Michael


    The behavior and fate of biological organisms are to a large extent dictated by their environment, which can be often viewed as a collection of features and constraints governed by physics laws. Since biological systems comprise networks of molecular interactions, one such key physical property is temperature, whose variations directly affect the rates of biochemical reactions involved. For instance, temperature is known to control many gene regulatory circuits responsible for pathogenicity in bacteria. One such example is type 1 fimbriae (T1F) -- the foremost virulence factor in uropathogenic E. coli (UPEC), which accounts for 80-90% of all community-acquired urinary tract infections (UTIs). The expression of T1F is randomly `phase variable', i.e. individual cells switch between virulent/fimbriate and avirulent/afimbriate phenotypes, with rates regulated by temperature. Our computational investigation of this process, which is based on FimB/FimE recombinase-mediated inversion of fimS DNA element, offers new insights into its discrete-stochastic kinetics. In particular, it elucidates the logic of T1F control optimization to the host temperature and contributes further understanding toward the development of novel therapeutic approaches to UPEC-caused UTIs.

  6. The Effect of Noseband Tightening on Horses' Behavior, Eye Temperature, and Cardiac Responses.

    Directory of Open Access Journals (Sweden)

    Kate Fenner

    Full Text Available Restrictive nosebands are common in equestrian sport. This is concerning, as recent evidence suggests that very tight nosebands can cause a physiological stress response, and may compromise welfare. The objective of the current study was to investigate relationships that noseband tightness has with oral behavior and with physiological changes that indicate a stress response, such as increases in eye temperature (measured with infrared thermography and heart rate and decreases in heart rate variability (HRV. Horses (n = 12 wearing a double bridle and crank noseband, as is common in dressage at elite levels, were randomly assigned to four treatments: unfastened noseband (UN, conventional area under noseband (CAUN with two fingers of space available under the noseband, half conventional area under noseband (HCAUN with one finger of space under the noseband, and no area under the noseband (NAUN. During the tightest treatment (NAUN, horse heart rate increased (P = 0.003, HRV decreased (P < 0.001, and eye temperature increased (P = 0.011 compared with baseline readings, indicating a physiological stress response. The behavioral results suggest some effects from bits alone but the chief findings are the physiological readings that reflect responses to the nosebands at their tightest. Chewing decreased during the HCAUN (P < 0.001 and NAUN (P < 0.001 treatments. Yawning rates were negligible in all treatments. Similarly, licking was eliminated by the NAUN treatment. Following the removal of the noseband and double bridle during the recovery session, yawning (P = 0.015, swallowing (P = 0.003, and licking (P < 0.001 significantly increased compared with baseline, indicating a post-inhibitory rebound response. This suggests a rise in motivation to perform these behaviors and implies that their inhibition may place horses in a state of deprivation. It is evident that a very tight noseband can cause physiological stress responses and inhibit the expression of

  7. Application of multi-pass high pressure homogenization under variable temperature regimes to induce autolysis of wine yeasts. (United States)

    Comuzzo, Piergiorgio; Calligaris, Sonia; Iacumin, Lucilla; Ginaldi, Federica; Voce, Sabrina; Zironi, Roberto


    The effects of the number of passes and processing temperature management (controlled vs. uncontrolled) were investigated during high pressure homogenization-induced autolysis of Saccharomyces bayanus wine yeasts, treated at 150MPa. Both variables were able to affect cell viability, and the release of soluble molecules (free amino acids, proteins and glucidic colloids), but the effect of temperature was more important. S. bayanus cells were completely inactivated in 10 passes without temperature control (corresponding to a processing temperature of 75°C). The two processing variables also affected the volatile composition of the autolysates produced: higher temperatures led to a lower concentration of volatile compounds. The management of the operating conditions may allow the compositional characteristics of the products to be modulated, making them suitable for different winemaking applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Indian summer monsoon rainfall variability during 2014 and 2015 and associated Indo-Pacific upper ocean temperature patterns (United States)

    Kakatkar, Rashmi; Gnanaseelan, C.; Chowdary, J. S.; Parekh, Anant; Deepa, J. S.


    In this study, factors responsible for the deficit Indian Summer Monsoon (ISM) rainfall in 2014 and 2015 and the ability of Indian Institute of Tropical Meteorology-Global Ocean Data Assimilation System (IITM-GODAS) in representing the oceanic features are examined. IITM-GODAS has been used to provide initial conditions for seasonal forecast in India during 2014 and 2015. The years 2014 and 2015 witnessed deficit ISM rainfall but were evolved from two entirely different preconditions over Pacific. This raises concern over the present understanding of the role of Pacific Ocean on ISM variability. Analysis reveals that the mechanisms associated with the rainfall deficit over the Indian Subcontinent are different in the two years. It is found that remote forcing in summer of 2015 due to El Niño is mostly responsible for the deficit monsoon rainfall through changes in Walker circulation and large-scale subsidence. In the case of the summer of 2014, both local circulation with anomalous anticyclone over central India and intrusion of mid-latitude dry winds from north have contributed for the deficit rainfall. In addition to the above, Tropical Indian Ocean (TIO) sea surface temperature (SST) and remote forcing from Pacific Ocean also modulated the ISM rainfall. It is observed that Pacific SST warming has extended westward in 2014, making it a basin scale warming unlike the strong El Niño year 2015. The eastern equatorial Indian Ocean is anomalously warmer than west in summer of 2014, and vice versa in 2015. These differences in SST in both tropical Pacific and TIO have considerable impact on ISM rainfall in 2014 and 2015. The study reveals that initializing coupled forecast models with proper upper ocean temperature over the Indo-Pacific is therefore essential for improved model forecast. It is important to note that the IITM-GODAS which assimilates only array for real-time geostrophic oceanography (ARGO) temperature and salinity profiles could capture most of the

  9. Spectral Kernel Approach to Study Radiative Response of Climate Variables and Interannual Variability of Reflected Solar Spectrum (United States)

    Jin, Zhonghai; Wielicki, Bruce A.; Loukachine, Constantin; Charlock, Thomas P.; Young, David; Noeel, Stefan


    The radiative kernel approach provides a simple way to separate the radiative response to different climate parameters and to decompose the feedback into radiative and climate response components. Using CERES/MODIS/Geostationary data, we calculated and analyzed the solar spectral reflectance kernels for various climate parameters on zonal, regional, and global spatial scales. The kernel linearity is tested. Errors in the kernel due to nonlinearity can vary strongly depending on climate parameter, wavelength, surface, and solar elevation; they are large in some absorption bands for some parameters but are negligible in most conditions. The spectral kernels are used to calculate the radiative responses to different climate parameter changes in different latitudes. The results show that the radiative response in high latitudes is sensitive to the coverage of snow and sea ice. The radiative response in low latitudes is contributed mainly by cloud property changes, especially cloud fraction and optical depth. The large cloud height effect is confined to absorption bands, while the cloud particle size effect is found mainly in the near infrared. The kernel approach, which is based on calculations using CERES retrievals, is then tested by direct comparison with spectral measurements from Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) (a different instrument on a different spacecraft). The monthly mean interannual variability of spectral reflectance based on the kernel technique is consistent with satellite observations over the ocean, but not over land, where both model and data have large uncertainty. RMS errors in kernel ]derived monthly global mean reflectance over the ocean compared to observations are about 0.001, and the sampling error is likely a major component.

  10. A latent class distance association model for cross-classified data with a categorical response variable. (United States)

    Vera, José Fernando; de Rooij, Mark; Heiser, Willem J


    In this paper we propose a latent class distance association model for clustering in the predictor space of large contingency tables with a categorical response variable. The rows of such a table are characterized as profiles of a set of explanatory variables, while the columns represent a single outcome variable. In many cases such tables are sparse, with many zero entries, which makes traditional models problematic. By clustering the row profiles into a few specific classes and representing these together with the categories of the response variable in a low-dimensional Euclidean space using a distance association model, a parsimonious prediction model can be obtained. A generalized EM algorithm is proposed to estimate the model parameters and the adjusted Bayesian information criterion statistic is employed to test the number of mixture components and the dimensionality of the representation. An empirical example highlighting the advantages of the new approach and comparing it with traditional approaches is presented. © 2014 The British Psychological Society.

  11. Heart rate variability response to mental arithmetic stress in patients with schizophrenia Autonomic response to stress in schizophrenia

    NARCIS (Netherlands)

    Castro, Mariana N.; Vigo, Daniel E.; Weidema, Hylke; Fahrer, Rodolfo D.; Chu, Elvina M.; De Achaval, Delfina; Nogues, Martin; Leiguarda, Ramon C.; Cardinali, Daniel P.; Guinjoan, Salvador N.

    Background: The vulnerability-stress hypothesis is an established model of schizophrenia symptom formation. We sought to characterise the pattern of the cardiac autonomic response to mental arithmetic stress in patients with stable schizophrenia. Methods: We performed heart rate variability (HRV)

  12. Inter- and intrapatient variability of facial nerve response areas in the floor of the fourth ventricle. (United States)

    Bertalanffy, Helmut; Tissira, Nadir; Krayenbühl, Niklaus; Bozinov, Oliver; Sarnthein, Johannes


    Surgical exposure of intrinsic brainstem lesions through the floor of the 4th ventricle requires precise identification of facial nerve (CN VII) fibers to avoid damage. To assess the shape, size, and variability of the area where the facial nerve can be stimulated electrophysiologically on the surface of the rhomboid fossa. Over a period of 18 months, 20 patients were operated on for various brainstem and/or cerebellar lesions. Facial nerve fibers were stimulated to yield compound muscle action potentials (CMAP) in the target muscles. Using the sites of CMAP yield, a detailed functional map of the rhomboid fossa was constructed for each patient. Lesions resected included 14 gliomas, 5 cavernomas, and 1 epidermoid cyst. Of 40 response areas mapped, 19 reached the median sulcus. The distance from the obex to the caudal border of the response area ranged from 8 to 27 mm (median, 17 mm). The rostrocaudal length of the response area ranged from 2 to 15 mm (median, 5 mm). Facial nerve response areas showed large variability in size and position, even in patients with significant distance between the facial colliculus and underlying pathological lesion. Lesions located close to the facial colliculus markedly distorted the response area. This is the first documentation of variability in the CN VII response area in the rhomboid fossa. Knowledge of this remarkable variability may facilitate the assessment of safe entry zones to the brainstem and may contribute to improved outcome following neurosurgical interventions within this sensitive area of the brain.

  13. The influence of riparian woodland on the spatial and temporal variability of stream water temperatures in an upland salmon stream

    Directory of Open Access Journals (Sweden)

    I. A. Malcolm


    Full Text Available The spatio-temporal variability of stream water temperatures was investigated at six locations on the Girnock Burn (30km2 catchment, Cairngorms, Scotland over three hydrological years between 1998 and 2002. The key site-specific factors affecting the hydrology and climatology of the sampling points were investigated as a basis for physical process inference. Particular emphasis was placed on assessing the effects of riparian forest in the lower catchment versus the heather moorland riparian zones that are spatially dominant in the upper catchment. The findings were related to river heat budget studies that provided process detail. Gross changes in stream temperature were affected by the annual cycle of incoming solar radiation and seasonal changes in hydrological and climatological conditions. Inter-annual variation in these controlling variables resulted in inter-annual variability in thermal regime. However, more subtle inter-site differences reflected the impact of site-specific characteristics on various components of the river energy budget. Inter-site variability was most apparent at shorter time scales, during the summer months and for higher stream temperatures. Riparian woodland in the lower catchment had a substantial impact on thermal regime, reducing diel variability (over a period of 24 hours and temperature extremes. Observed inter-site differences are likely to have a substantial effect on freshwater ecology in general and salmonid fish in particular. Keywords: temperature, thermal regime, forest, salmon, hydrology, Girnock Burn, Cairngorm

  14. Mixing times towards demographic equilibrium in insect populations with temperature variable age structures. (United States)

    Damos, Petros


    In this study, we use entropy related mixing rate modules to measure the effects of temperature on insect population stability and demographic breakdown. The uncertainty in the age of the mother of a randomly chosen newborn, and how it is moved after a finite act of time steps, is modeled using a stochastic transformation of the Leslie matrix. Age classes are represented as a cycle graph and its transitions towards the stable age distribution are brought forth as an exact Markov chain. The dynamics of divergence, from a non equilibrium state towards equilibrium, are evaluated using the Kolmogorov-Sinai entropy. Moreover, Kullback-Leibler distance is applied as information-theoretic measure to estimate exact mixing times of age transitions probabilities towards equilibrium. Using empirically data, we show that on the initial conditions and simulated projection's trough time, that population entropy can effectively be applied to detect demographic variability towards equilibrium under different temperature conditions. Changes in entropy are correlated with the fluctuations of the insect population decay rates (i.e. demographic stability towards equilibrium). Moreover, shorter mixing times are directly linked to lower entropy rates and vice versa. This may be linked to the properties of the insect model system, which in contrast to warm blooded animals has the ability to greatly change its metabolic and demographic rates. Moreover, population entropy and the related distance measures that are applied, provide a means to measure these rates. The current results and model projections provide clear biological evidence why dynamic population entropy may be useful to measure population stability. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Adriatic Sea surface temperature and ocean colour variability during the MFSPP

    Directory of Open Access Journals (Sweden)

    E. Böhm


    Full Text Available Two years and six months of night-time Advanced Very High Resolution Radiometer (AVHRR sea surface temperature (SST and daytime Sea viewing Wide Field of view Sensor (SeaWiFS data collected during the MFSPP have been used to examine spatial and temporal variability of SST and chlorophyll (Chl in the Adriatic Sea. Flows along the Albanian and the Italian coasts can be distinguished year-round in the monthly averaged Chl but only in the colder months in the monthly averaged SST’s. The Chl monthly-averaged fields supply less information on circulation features away from coastal boundaries and where conditions are generally oligotrophic, except for the early spring bloom in the Southern Adriatic Gyre. To better characterise the year-to-year and seasonal variability, exploratory data analysis techniques, particularly the plotting of multiple Chl-SST histograms, are employed to make joint quantitative use of monthly-averaged fields. Modal water mass (MW, corresponding to the Chl-SST pairs in the neighbourhood of the maximum of each monthly histogram, are chosen to represent the temporal and spatial evolution of the prevalent processes and their variability in the Adriatic Sea. Over an annual cycle, the MW followed a triangular path with the most pronounced seasonal and interannual variations in both Chl-SST properties and spatial distributions of the MW in the colder part of the year. The winter of 1999 is the colder (by at least 0.5°C and most eutrophic (by 0.2 mg/m 3. The fall of the year 2000 is characterised by the lack of cooling in the month of November that was observed in the previous year. In addition to characterising the MW, the two-dimensional histogram technique allows a distinction to be made between different months in terms of the spread of SST values at a given Chl concentration. During spring and summer, the spread is minimal indicating surface homothermal conditions. In fall and winter, on the other hand, a spread of points

  16. Physiological, proteomic and transcriptional responses of wheat to combination of drought or waterlogging with late spring low temperature

    DEFF Research Database (Denmark)

    Li, Xiangnan; Cai, Jian; Liu, Fulai


    Spring low temperature events affect winter wheat (Triticum aestivum L.) during late vegetative or reproductive development, exposing plants to a subzero low temperature stress when winter hardening is lost. The increased climatic variability results in wheat being exposed to more frequent adverse...... impacts of combined low temperature and water stress, including drought and waterlogging. The responses of potted wheat plants cultivated in climatic chambers to these environmental perturbations were investigated at physiological, proteomic and transcriptional levels. At the physiological level...... in chloroplasts and mitochondria of leaf under low temperature. Further proteomic analysis revealed that the oxidative stress defence, C metabolism and photosynthesis related proteins were modulated by the combined low temperature and water stress. Collectively, the results indicate that impairment...

  17. Temperature and relative humidity dependence of radiochromic film dosimeter response to gamma electron radiation

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Puhl, J.M.; Miller, A.


    on some earlier studies, their response functions have been reported to be dependent on the temperature and relative humidity during irradiation. The present study investigates differences in response over practical ranges of temperature, relative humidity, dose, and for different recent batches of films...... humidity) and should be calibrated under environmental conditions (temperature) at which they will be used routinely....

  18. The Role of Auxiliary Variables in Deterministic and Deterministic-Stochastic Spatial Models of Air Temperature in Poland (United States)

    Szymanowski, Mariusz; Kryza, Maciej


    Our study examines the role of auxiliary variables in the process of spatial modelling and mapping of climatological elements, with air temperature in Poland used as an example. The multivariable algorithms are the most frequently applied for spatialization of air temperature, and their results in many studies are proved to be better in comparison to those obtained by various one-dimensional techniques. In most of the previous studies, two main strategies were used to perform multidimensional spatial interpolation of air temperature. First, it was accepted that all variables significantly correlated with air temperature should be incorporated into the model. Second, it was assumed that the more spatial variation of air temperature was deterministically explained, the better was the quality of spatial interpolation. The main goal of the paper was to examine both above-mentioned assumptions. The analysis was performed using data from 250 meteorological stations and for 69 air temperature cases aggregated on different levels: from daily means to 10-year annual mean. Two cases were considered for detailed analysis. The set of potential auxiliary variables covered 11 environmental predictors of air temperature. Another purpose of the study was to compare the results of interpolation given by various multivariable methods using the same set of explanatory variables. Two regression models: multiple linear (MLR) and geographically weighted (GWR) method, as well as their extensions to the regression-kriging form, MLRK and GWRK, respectively, were examined. Stepwise regression was used to select variables for the individual models and the cross-validation method was used to validate the results with a special attention paid to statistically significant improvement of the model using the mean absolute error (MAE) criterion. The main results of this study led to rejection of both assumptions considered. Usually, including more than two or three of the most significantly

  19. Temperature-driven global sea-level variability in the Common Era (United States)

    Kopp, Robert E.; Kemp, Andrew C.; Bittermann, Klaus; Horton, Benjamin P.; Donnelly, Jeffrey P.; Gehrels, W. Roland; Hay, Carling C.; Mitrovica, Jerry X.; Morrow, Eric D.; Rahmstorf, Stefan


    We assess the relationship between temperature and global sea-level (GSL) variability over the Common Era through a statistical metaanalysis of proxy relative sea-level reconstructions and tide-gauge data. GSL rose at 0.1 ± 0.1 mm/y (2σ) over 0–700 CE. A GSL fall of 0.2 ± 0.2 mm/y over 1000–1400 CE is associated with ∼0.2 °C global mean cooling. A significant GSL acceleration began in the 19th century and yielded a 20th century rise that is extremely likely (probability P≥0.95) faster than during any of the previous 27 centuries. A semiempirical model calibrated against the GSL reconstruction indicates that, in the absence of anthropogenic climate change, it is extremely likely (P=0.95) that 20th century GSL would have risen by less than 51% of the observed 13.8±1.5 cm. The new semiempirical model largely reconciles previous differences between semiempirical 21st century GSL projections and the process model-based projections summarized in the Intergovernmental Panel on Climate Change’s Fifth Assessment Report. PMID:26903659

  20. The analytical description of high temperature tensile creep for cavitating materials subjected to time variable loads

    International Nuclear Information System (INIS)

    Bocek, M.

    A phenomenological cavitation model is presented by means of which the life time as well as the creep curve equations can be calculated for cavitating materials subjected to time variable tensile loads. The model precludes the proportionality between the damage A and the damage rate (dA/dt) resp. Both are connected by the life time function tau. The latter is derived from static stress rupture tests and contains the loading conditions. From this model the life fraction rule (LFR) is derived. The model is used to calculate the creep curves of cavitating materials subjected at high temperatures to non-stationary tensile loading conditions. In the present paper the following loading procedures are considered: creep at constant load F and true stress s; creep at linear load increase ((dF/dt)=const) and creep at constant load amplitude cycling (CLAC). For these loading procedures the creep equations for cavitating and non-cavitating specimens are derived. Under comparable conditions the creep rate of cavitating materials are higher than for non-cavitating ones. (author)

  1. Design of a High Temperature Radiator for the Variable Specific Impulse Magnetoplasma Rocket (United States)

    Sheth, Rubik B.; Ungar, Eugene K.; Chambliss, Joe P.


    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR), currently under development by Ad Astra Rocket Company (Webster, TX), is a unique propulsion system that could change the way space propulsion is performed. VASIMR's efficiency, when compared to that of a conventional chemical rocket, reduces the propellant needed for exploration missions by a factor of 10. Currently plans include flight tests of a 200 kW VASIMR system, titled VF-200, on the International Space Station (ISS). The VF-200 will consist of two 100 kW thruster units packaged together in one engine bus. Each thruster core generates 27 kW of waste heat during its 15 minute firing time. The rocket core will be maintained between 283 and 573 K by a pumped thermal control loop. The design of a high temperature radiator is a unique challenge for the vehicle design. This paper will discuss the path taken to develop a steady state and transient-based radiator design. The paper will describe the radiator design option selected for the VASIMR thermal control system for use on ISS, and how the system relates to future exploration vehicles.

  2. The spatial variability of air temperature and nocturnal urban heat island intensity in the city of Brno, Czech Republic

    Directory of Open Access Journals (Sweden)

    Dobrovolný Petr


    Full Text Available This study seeks to quantify the effects of a number of factors on the nocturnal air temperature field in a medium-sized central European city located in complex terrain. The main data sources consist of mobile air temperature measurements and a geographical database. Temperature measurements were taken along several profiles through the city centre and were made under a clear sky with no advection. Altogether nine sets of detailed measurements, in all seasons, were assembled. Altitude, quantity of vegetation, density of buildings and the structure of the transportation (road system were considered as explanatory variables. The result is that the normalized difference vegetation index (NDVI and the density of buildings were the most important factors, each of them explaining a substantial part (more than 50% of overall air temperature variability. Mobile measurements with NDVI values as a covariate were used for interpolation of air temperature for the entire study area. The spatial variability of nocturnal air temperature and UHI intensity in Brno is the main output presented. Air temperatures interpolated from mobile measurements and NDVI values indicate that the mean urban heat island (UHI intensity in the early night in summer is at its highest (approximately 5 °C in the city centre and decreases towards the suburban areas.

  3. Role of the upper ocean structure in the response of ENSO-like SST variability to global warming

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Sang-Wook [Hanyang University, Department of Environmental Marine Science, Ansan (Korea); Dewitte, Boris [Laboratoire d' Etude en Geophysique et Oceanographie Spatiale, Toulouse (France); Yim, Bo Young; Noh, Yign [Yonsei University, Department of Atmospheric Sciences, Global Environmental Laboratory, Seoul (Korea)


    The response of El Nino and Southern Oscillation (ENSO)-like variability to global warming varies comparatively between the two different climate system models, i.e., the Meteorological Research Institute (MRI) and Geophysical Fluid Dynamics Laboratory (GFDL) Coupled General Circulation Models (CGCMs). Here, we examine the role of the simulated upper ocean temperature structure in the different sensitivities of the simulated ENSO variability in the models based on the different level of CO{sub 2} concentrations. In the MRI model, the sea surface temperature (SST) undergoes a rather drastic modification, namely a tendency toward a permanent El Nino-like state. This is associated with an enhanced stratification which results in greater ENSO amplitude for the MRI model. On the other hand, the ENSO simulated by GFDL model is hardly modified although the mean temperature in the near surface layer increases. In order to understand the associated mechanisms we carry out a vertical mode decomposition of the mean equatorial stratification and a simplified heat balance analysis using an intermediate tropical Pacific model tuned from the CGCM outputs. It is found that in the MRI model the increased stratification is associated with an enhancement of the zonal advective feedback and the non-linear advection. In the GFDL model, on the other hand, the thermocline variability and associated anomalous vertical advection are reduced in the eastern equatorial Pacific under global warming, which erodes the thermocline feedback and explains why the ENSO amplitude is reduced in a warmer climate in this model. It is suggested that change in stratification associated with global warming impacts the equatorial wave dynamics in a way that enhances the second baroclinic mode over the gravest one, which leads to the change in feedback processes in the CGCMs. Our results illustrate that the upper ocean vertical structure simulated in the CGCMs is a key parameter of the sensitivity of ENSO

  4. Seasonal differences in human responses to increasing temperatures

    DEFF Research Database (Denmark)

    Kitazawa, Sachie; Andersen, Rune Korsholm; Wargocki, Pawel


    to be sleepier. Heart rate slightly increased during exposure, and SpO2 and ETCO2 began to decrease while core temperature started to increase. Performance of Tsai-partington test and addition test improved during exposures due to learning though lesser in winter. Results show negative effects of the temperature......Experiments were conducted in late summer and winter with 80 young and elderly Danish subjects exposed for 3.5 hours in a climate chamber to the temperature increasing from 24°C to 35.2°C at a rate of 3.7K/h. Psychological and physiological measurements were performed during exposure and subjects...... assessed comfort and acute health symptoms. Thermal sensation increased with increasing chamber temperature and did not differ during late summer and winter exposures. Skin temperature increased with increasing temperature and was slightly but significantly higher in the late summer in the first half...

  5. Optimization of process variables on flexural properties of epoxy/organo-montmorillonite nanocomposite by response surface methodology

    Directory of Open Access Journals (Sweden)


    Full Text Available This study attempted to investigate the preparation and optimization of the flexural properties for epoxy/organomontmorillonite (OMMT nanocomposites. In-situ polymerization method was used to prepare epoxy/OMMT nanocomposites. The diglycidyl ether bisphenol A (DGEBA and curing agent were mixed first, followed by the addition of OMMT. In this study, computer aided statistical methods of experimental design (Response Surface Methodology, RSM was used to investigate the process variables on the flexural properties of epoxy/4wt% OMMT nanocomposites. Speed of mechanical stirrer, post-curing time and post-curing temperature were chosen as process variables in the experimental design. Results showed that the speed of mechanical stirrer, post-curing time and post-curing temperature were able to influence the flexural modulus and flexural yield stress of epoxy/4 wt% OMMT nanocomposites. The results of optimization showed that the design of experiment (DOE has six combination of operating variables which have been obtained in order to attain the greatest overall desirability.

  6. Response of the mean global vegetation distribution to interannual climate variability

    Energy Technology Data Exchange (ETDEWEB)

    Notaro, Michael [University of Wisconsin-Madison, Center for Climatic Research, Madison, WI (United States)


    The impact of interannual variability in temperature and precipitation on global terrestrial ecosystems is investigated using a dynamic global vegetation model driven by gridded climate observations for the twentieth century. Contrasting simulations are driven either by repeated mean climatology or raw climate data with interannual variability included. Interannual climate variability reduces net global vegetation cover, particularly over semi-arid regions, and favors the expansion of grass cover at the expense of tree cover, due to differences in growth rates, fire impacts, and interception. The area burnt by global fires is substantially enhanced by interannual precipitation variability. The current position of the central United States' ecotone, with forests to the east and grasslands to the west, is largely attributed to climate variability. Among woody vegetation, climate variability supports expanded deciduous forest growth and diminished evergreen forest growth, due to difference in bioclimatic limits, leaf longevity, interception rates, and rooting depth. These results offer insight into future ecosystem distributions since climate models generally predict an increase in climate variability and extremes. (orig.)

  7. Low temperature resistivity studies of SmB6: Observation of two-dimensional variable-range hopping conductivity (United States)

    Batkova, Marianna; Batko, Ivan; Gabáni, Slavomír; Gažo, Emil; Konovalova, Elena; Filippov, Vladimir


    We studied electrical resistance of a single-crystalline SmB6 sample with a focus on the region of the "low-temperature resistivity plateau". Our observations did not show any true saturation of the electrical resistance at temperatures below 3 K down to 70 mK. According to our findings, temperature dependence of the electrical conduction in a certain temperature interval above 70 mK can be decomposed into a temperature-independent term and a temperature-activated term that can be described by variable-range hopping formula for two-dimensional systems, exp [ -(T0 / T) 1 / 3 ]. Thus, our results indicate importance of hopping type of electrical transport in the near-surface region of SmB6.

  8. Physiological responses to nitrogen and sulphur addition and raised temperature in Sphagnum balticum. (United States)

    Granath, Gustaf; Wiedermann, Magdalena M; Strengbom, Joachim


    Sphagnum, the main genus which forms boreal peat, is strongly affected by N and S deposition and raised temperature, but the physiological mechanisms behind the responses are largely unknown. We measured maximum photosynthetic rate (NP(max)), maximum efficiency of photosystem II [variable fluorescence (F (v))/maximum fluorescence yield (F (m))] and concentrations of N, C, chlorophyll and carotenoids as responses to N and S addition and increased temperature in Sphagnum balticum (a widespread species in the northern peatlands) in a 12-year factorial experiment. NP(max) did not differ between control (0.2 g N m(-2) year(-1)) and high N (3.0 g N m(-2) year(-1)), but was higher in the mid N treatment (1.5 g N m(-2) year(-1)). N, C, carotenoids and chlorophyll concentration increased in shoot apices after N addition. F (v)/F (m) did not differ between N treatments. Increased temperature (+3.6 degrees C) had a small negative effect on N concentration, but had no significant effect on NP(max) or F (v)/F (m). Addition of 2 g S m(-2) year(-1) showed a weak negative effect on NP(max) and F (v)/F (m). Our results suggest a unimodal response of NP(max) to N addition and tissue N concentration in S. balticum, with an optimum N concentration for photosynthetic rate of ~13 mg N g(-1). In conclusion, high S deposition may reduce photosynthetic capacity in Sphagnum, but the negative effects may be relaxed under high N availability. We suggest that previously reported negative effects on Sphagnum productivity under high N deposition are not related to negative effects on the photosynthetic apparatus, but differences in optimum N concentration among Sphagnum species may affect their competitive ability under different N deposition regimes.

  9. Physiological responses of rice to increased day and night temperatures

    NARCIS (Netherlands)

    Shi, Wanju


    A more rapid increase in night-time temperature compared with day-time temperature and the increased frequency of heat waves associated with climate change present a serious threat to rice (Oryza sativa L.) production and food security. This thesis aims to understand the impact of high

  10. Ocean acidification increases the sensitivity of and variability in physiological responses of an intertidal limpet to thermal stress (United States)

    Wang, Jie; Russell, Bayden D.; Ding, Meng-Wen; Dong, Yun-Wei


    Understanding physiological responses of organisms to warming and ocean acidification is the first step towards predicting the potential population- and community-level ecological impacts of these stressors. Increasingly, physiological plasticity is being recognized as important for organisms to adapt to the changing microclimates. Here, we evaluate the importance of physiological plasticity for coping with ocean acidification and elevated temperature, and its variability among individuals, of the intertidal limpet Cellana toreuma from the same population in Xiamen. Limpets were collected from shaded mid-intertidal rock surfaces. They were acclimated under combinations of different pCO2 concentrations (400 and 1000 ppm, corresponding to a pH of 8.1 and 7.8) and temperatures (20 and 24 °C) in a short-term period (7 days), with the control conditions (20 °C and 400 ppm) representing the average annual temperature and present-day pCO2 level at the collection site. Heart rates (as a proxy for metabolic performance) and expression of genes encoding inducible and constitutive heat-shock proteins (hsp70 and hsc70) at different heat-shock temperatures (26, 30, 34, and 38 °C) were measured. Hsp70 and Hsc70 play important roles in protecting cells from heat stresses, but have different expression patterns, with Hsp70 significantly increased in expression during stress and Hsc70 constitutively expressed and only mildly induced during stress. Analysis of heart rate showed significantly higher temperature coefficients (Q10 rates) for limpets at 20 °C than at 24 °C and post-acclimation thermal sensitivity of limpets at 400 ppm was lower than at 1000 ppm. Expression of hsp70 linearly increased with the increasing heat-shock temperatures, with the largest slope occurring in limpets acclimated under a future scenario (24 °C and 1000 ppm pCO2). These results suggested that limpets showed increased sensitivity and stress response under future conditions. Furthermore, the

  11. Assimilation of temperature and hydraulic gradients for quantifying the spatial variability of streambed hydraulics (United States)

    Huang, Xiang; Andrews, Charles B.; Liu, Jie; Yao, Yingying; Liu, Chuankun; Tyler, Scott W.; Selker, John S.; Zheng, Chunmiao


    Understanding the spatial and temporal characteristics of water flux into or out of shallow aquifers is imperative for water resources management and eco-environmental conservation. In this study, the spatial variability in the vertical specific fluxes and hydraulic conductivities in a streambed were evaluated by integrating distributed temperature sensing (DTS) data and vertical hydraulic gradients into an ensemble Kalman filter (EnKF) and smoother (EnKS) and an empirical thermal-mixing model. The formulation of the EnKF/EnKS assimilation scheme is based on a discretized 1D advection-conduction equation of heat transfer in the streambed. We first systematically tested a synthetic case and performed quantitative and statistical analyses to evaluate the performance of the assimilation schemes. Then a real-world case was evaluated to calculate assimilated specific flux. An initial estimate of the spatial distributions of the vertical hydraulic gradients was obtained from an empirical thermal-mixing model under steady-state conditions using a constant vertical hydraulic conductivity. Then, this initial estimate was updated by repeatedly dividing the assimilated specific flux by estimates of the vertical hydraulic gradients to obtain a refined spatial distribution of vertical hydraulic gradients and vertical hydraulic conductivities. Our results indicate that optimal parameters can be derived with fewer iterations but greater simulation effort using the EnKS compared with the EnKF. For the field application in a stream segment of the Heihe River Basin in northwest China, the average vertical hydraulic conductivities in the streambed varied over three orders of magnitude (5 × 10-1 to 5 × 102 m/d). The specific fluxes ranged from near zero (qz < ±0.05 m/d) to ±1.0 m/d, while the vertical hydraulic gradients were within the range of -0.2 to 0.15 m/m. The highest and most variable fluxes occurred adjacent to a debris-dam and bridge pier. This phenomenon is very likely

  12. Are Simulated and Observed Twentieth Century Tropical Pacific Sea Surface Temperature Trends Significant Relative to Internal Variability? (United States)

    Coats, S.; Karnauskas, K. B.


    Historical trends in the tropical Pacific zonal sea surface temperature gradient (SST gradient) are analyzed herein using 41 climate models (83 simulations) and 5 observational data sets. A linear inverse model is trained on each simulation and observational data set to assess if trends in the SST gradient are significant relative to the stationary statistics of internal variability, as would suggest an important role for external forcings such as anthropogenic greenhouse gasses. None of the 83 simulations have a positive trend in the SST gradient, a strengthening of the climatological SST gradient with more warming in the western than eastern tropical Pacific, as large as the mean trend across the five observational data sets. If the observed trends are anthropogenically forced, this discrepancy suggests that state-of-the-art climate models are not capturing the observed response of the tropical Pacific to anthropogenic forcing, with serious implications for confidence in future climate projections. There are caveats to this interpretation, however, as some climate models have a significant strengthening of the SST gradient between 1900 and 2013 Common Era, though smaller in magnitude than the observational data sets, and the strengthening in three out of five observational data sets is insignificant. When combined with observational uncertainties and the possibility of centennial time scale internal variability not sampled by the linear inverse model, this suggests that confident validation of anthropogenic SST gradient trends in climate models will require further emergence of anthropogenic trends. Regardless, the differences in SST gradient trends between climate models and observational data sets are concerning and motivate the need for process-level validation of the atmosphere-ocean dynamics relevant to climate change in the tropical Pacific.

  13. Remodeling of the Streptococcus agalactiae transcriptome in response to growth temperature.

    Directory of Open Access Journals (Sweden)

    Laurent Mereghetti

    Full Text Available BACKGROUND: To act as a commensal bacterium and a pathogen in humans and animals, Streptococcus agalactiae (group B streptococcus, GBS must be able to monitor and adapt to different environmental conditions. Temperature variation is a one of the most commonly encountered variables. METHODOLOGY/PRINCIPAL FINDINGS: To understand the extent to which GBS modify gene expression in response to temperatures encountered in the various hosts, we conducted a whole genome transcriptome analysis of organisms grown at 30 degrees C and 40 degrees C. We identified extensive transcriptome remodeling at various stages of growth, especially in the stationary phase (significant transcript changes occurred for 25% of the genes. A large proportion of genes involved in metabolism was up-regulated at 30 degrees C in stationary phase. Conversely, genes up-regulated at 40 degrees C relative to 30 degrees C include those encoding virulence factors such as hemolysins and extracellular secreted proteins with LPXTG motifs. Over-expression of hemolysins was linked to larger zones of hemolysis and enhanced hemolytic activity at 40 degrees C. A key theme identified by our study was that genes involved in purine metabolism and iron acquisition were significantly up-regulated at 40 degrees C. CONCLUSION/SIGNIFICANCE: Growth of GBS in vitro at different temperatures resulted in extensive remodeling of the transcriptome, including genes encoding proven and putative virulence genes. The data provide extensive new leads for molecular pathogenesis research.

  14. The physiological basis for regeneration response to variable retention harvest treatments in three pine species (United States)

    Matthew D. Powers; Kurt S. Pregitzer; Brian J. Palik; Christopher R. Webster


    Variable retention harvesting (VRH) is promoted for enhancing biodiversity and ecosystem processes in managed forests, but regeneration responses to the complex stand structures that result from VRH are poorly understood. We analyzed foliar stable carbon isotope ratios (δ13C), oxygen isotope ratios (δ18O...

  15. Resistance to Change and Preference for Variable versus Fixed Response Sequences (United States)

    Arantes, Joana; Berg, Mark E.; Le, Dien; Grace, Randolph C.


    In Experiment 1, 4 pigeons were trained on a multiple chain schedule in which the initial link was a variable-interval (VI) 20-s schedule signalled by a red or green center key, and terminal links required four responses made to the left (L) and/or right (R) keys. In the REPEAT component, signalled by red keylights, only LRLR terminal-link…

  16. A longitudinal study in youth of heart rate variability at rest and in response to stress

    NARCIS (Netherlands)

    Li, Zhibin; Snieder, Harold; Su, Shaoyong; Ding, Xiuhua; Thayer, Julian F.; Treiber, Frank A.; Wang, Xiaoling

    Background: Few longitudinal studies have examined ethnic and sex differences, predictors and tracking stabilities of heart rate variability (HRV) at rest and in response to stress in youths and young adults. Methods: Two evaluations were performed approximately 1.5 years apart on 399 youths and

  17. Bayesian modeling of measurement error in predictor variables using item response theory

    NARCIS (Netherlands)

    Fox, Gerardus J.A.; Glas, Cornelis A.W.


    This paper focuses on handling measurement error in predictor variables using item response theory (IRT). Measurement error is of great important in assessment of theoretical constructs, such as intelligence or the school climate. Measurement error is modeled by treating the predictors as unobserved

  18. Does Response Variability Predict Distractibility among Adults with Attention-Deficit/Hyperactivity Disorder? (United States)

    Adams, Zachary W.; Roberts, Walter M.; Milich, Richard; Fillmore, Mark T.


    Increased intraindividual variability in response time (RTSD) has been observed reliably in attention-deficit/hyperactivity disorder (ADHD) and has often been used as a measure of inattention. RTSD is assumed to reflect attentional lapses and distractibility, though evidence for the validity of this connection is lacking. We assessed whether RTSD…

  19. Study on Short-term Variability of Ship Responses in Waves

    DEFF Research Database (Denmark)

    Iseki, Toshio; Nielsen, Ulrik Dam


    Short-term variability of ship responses is investigated from the view point of cross-spectrum analysis. In a steady state condition, it is well known that a certain length of sampled data are required for stable spectral analysis. However, the phase angle of the cross-spectra has not been discus...

  20. Dynamic Variables Fail to Predict Fluid Responsiveness in an Animal Model With Pericardial Effusion. (United States)

    Broch, Ole; Renner, Jochen; Meybohm, Patrick; Albrecht, Martin; Höcker, Jan; Haneya, Assad; Steinfath, Markus; Bein, Berthold; Gruenewald, Matthias


    The reliability of dynamic and volumetric variables of fluid responsiveness in the presence of pericardial effusion is still elusive. The aim of the present study was to investigate their predictive power in a porcine model with hemodynamic relevant pericardial effusion. A single-center animal investigation. Twelve German domestic pigs. Pigs were studied before and during pericardial effusion. Instrumentation included a pulmonary artery catheter and a transpulmonary thermodilution catheter in the femoral artery. Hemodynamic variables like cardiac output (COPAC) and stroke volume (SVPAC) derived from pulmonary artery catheter, global end-diastolic volume (GEDV), stroke volume variation (SVV), and pulse-pressure variation (PPV) were obtained. At baseline, SVV, PPV, GEDV, COPAC, and SVPAC reliably predicted fluid responsiveness (area under the curve 0.81 [p = 0.02], 0.82 [p = 0.02], 0.74 [p = 0.07], 0.74 [p = 0.07], 0.82 [p = 0.02]). After establishment of pericardial effusion the predictive power of dynamic variables was impaired and only COPAC and SVPAC and GEDV allowed significant prediction of fluid responsiveness (area under the curve 0.77 [p = 0.04], 0.76 [p = 0.05], 0.83 [p = 0.01]) with clinically relevant changes in threshold values. In this porcine model, hemodynamic relevant pericardial effusion abolished the ability of dynamic variables to predict fluid responsiveness. COPAC, SVPAC, and GEDV enabled prediction, but their threshold values were significantly changed. Copyright © 2016 Elsevier Inc. All rights reserved.


    Directory of Open Access Journals (Sweden)



    Full Text Available Vortex tube is a device that produces cold and hot air simultaneously from the source of compressed air. In this work an attempt has been made to investigate the effect of three controllable input variables namely diameter of the orifices, diameter of the nozzles and inlet pressure over the temperature difference in the cold side as output using Response Surface Methodology (RSM. Experiments are conducted using central composite design with three factors at three levels. The influence of vital parameters and interaction among these are investigated using analysis of variance (ANOVA. The proposed mathematical model in this study has proven to fit and in line with experimental values with a 95% confidence interval. It is found that the inlet pressure and diameter of nozzle are significant factors that affect the performance of vortex tube.

  2. Response of water temperatures and stratification to changing climate in three lakes with different morphometry (United States)

    Magee, Madeline R.; Wu, Chin H.


    Water temperatures and stratification are important drivers for ecological and water quality processes within lake systems, and changes in these with increases in air temperature and changes to wind speeds may have significant ecological consequences. To properly manage these systems under changing climate, it is important to understand the effects of increasing air temperatures and wind speed changes in lakes of different depths and surface areas. In this study, we simulate three lakes that vary in depth and surface area to elucidate the effects of the observed increasing air temperatures and decreasing wind speeds on lake thermal variables (water temperature, stratification dates, strength of stratification, and surface heat fluxes) over a century (1911-2014). For all three lakes, simulations showed that epilimnetic temperatures increased, hypolimnetic temperatures decreased, the length of the stratified season increased due to earlier stratification onset and later fall overturn, stability increased, and longwave and sensible heat fluxes at the surface increased. Overall, lake depth influences the presence of stratification, Schmidt stability, and differences in surface heat flux, while lake surface area influences differences in hypolimnion temperature, hypolimnetic heating, variability of Schmidt stability, and stratification onset and fall overturn dates. Larger surface area lakes have greater wind mixing due to increased surface momentum. Climate perturbations indicate that our larger study lakes have more variability in temperature and stratification variables than the smaller lakes, and this variability increases with larger wind speeds. For all study lakes, Pearson correlations and climate perturbation scenarios indicate that wind speed has a large effect on temperature and stratification variables, sometimes greater than changes in air temperature, and wind can act to either amplify or mitigate the effect of warmer air temperatures on lake thermal

  3. Long term variability of the annual hydrological regime and sensitivity to temperature phase shifts in Saxony/Germany (United States)

    Renner, M.; Bernhofer, C.


    The timing of the seasons strongly effects ecosystems and human activities. Recently, there is increasing evidence of changes in the timing of the seasons, such as earlier spring seasons detected in phenological records, advanced seasonal timing of surface temperature, earlier snow melt or streamflow timing. For water resources management there is a need to quantitatively describe the variability in the timing of hydrological regimes and to understand how climatic changes control the seasonal water budget of river basins on the regional scale. In this study, changes of the annual cycle of hydrological variables are analysed for 27 river basins in Saxony/Germany. Thereby monthly series of basin runoff ratios, the ratio of runoff and basin precipitation are investigated for changes and variability of their annual periodicity over the period 1930-2009. Approximating the annual cycle by the means of harmonic functions gave acceptable results, while only two parameters, phase and amplitude, are required. It has been found that the annual phase of runoff ratio, representing the timing of the hydrological regime, is subject to considerable year-to-year variability, being concurrent with basins in similar hydro-climatic conditions. Two distinct basin classes have been identified, whereby basin elevation has been found to be the delimiting factor. An increasing importance of snow on the basin water balance with elevation is apparent and mainly governs the temporal variability of the annual timing of hydrological regimes. Further there is evidence of coincident changes in trend direction (change points in 1971 and 1988) in snow melt influenced basins. In these basins the timing of the runoff ratio is significantly correlated with the timing of temperature, and effects on runoff by temperature phase changes are even amplified. Interestingly, temperature effects may explain the low frequent variability of the second change point until today. However, the first change point can

  4. Variable glacier response to atmospheric warming, northern Antarctic Peninsula, 1988–2009

    Directory of Open Access Journals (Sweden)

    B. J. Davies


    Full Text Available The northern Antarctic Peninsula has recently exhibited ice-shelf disintegration, glacier recession and acceleration. However, the dynamic response of land-terminating, ice-shelf tributary and tidewater glaciers has not yet been quantified or assessed for variability, and there are sparse data for glacier classification, morphology, area, length or altitude. This paper firstly classifies the area, length, altitude, slope, aspect, geomorphology, type and hypsometry of 194 glaciers on Trinity Peninsula, Vega Island and James Ross Island in 2009 AD. Secondly, this paper documents glacier change 1988–2009. In 2009, the glacierised area was 8140±262 km2. From 1988–2001, 90% of glaciers receded, and from 2001–2009, 79% receded. This equates to an area change of −4.4% for Trinity Peninsula eastern coast glaciers, −0.6% for western coast glaciers, and −35.0% for ice-shelf tributary glaciers from 1988–2001. Tidewater glaciers on the drier, cooler eastern Trinity Peninsula experienced fastest shrinkage from 1988–2001, with limited frontal change after 2001. Glaciers on the western Trinity Peninsula shrank less than those on the east. Land-terminating glaciers on James Ross Island shrank fastest in the period 1988–2001. This east-west difference is largely a result of orographic temperature and precipitation gradients across the Antarctic Peninsula, with warming temperatures affecting the precipitation-starved glaciers on the eastern coast more than on the western coast. Reduced shrinkage on the western Peninsula may be a result of higher snowfall, perhaps in conjunction with the fact that these glaciers are mostly grounded. Rates of area loss on the eastern side of Trinity Peninsula are slowing, which we attribute to the floating ice tongues receding into the fjords and reaching a new dynamic equilibrium. The rapid shrinkage of tidewater glaciers on James Ross Island is likely to continue because of their low elevations and

  5. Can oceanic reanalyses be used to assess recent anthropogenic changes and low-frequency internal variability of upper ocean temperature?

    Energy Technology Data Exchange (ETDEWEB)

    Corre, L.; Terray, L.; Weaver, A. [Cerfacs-CNRS, Toulouse (France); Balmaseda, M. [E.C.M.W.F, Reading (United Kingdom); Ribes, A. [CNRM-GAME, Meteo France-CNRS, Toulouse (France)


    A multivariate analysis of the upper ocean thermal structure is used to examine the recent long-term changes and decadal variability in the upper ocean heat content as represented by model-based ocean reanalyses and a model-independent objective analysis. The three variables used are the mean temperature above the 14 C isotherm, its depth and a fixed depth mean temperature (250 m mean temperature). The mean temperature above the 14 C isotherm is a convenient, albeit simple, way to isolate thermodynamical changes by filtering out dynamical changes related to thermocline vertical displacements. The global upper ocean observations and reanalyses exhibit very similar warming trends (0.045 C per decade) over the period 1965-2005, superimposed with marked decadal variability in the 1970s and 1980s. The spatial patterns of the regression between indices (representative of anthropogenic changes and known modes of internal decadal variability), and the three variables associated with the ocean heat content are used as fingerprint to separate out the different contributions. The choice of variables provides information about the local heat absorption, vertical distribution and horizontal redistribution of heat, this latter being suggestive of changes in ocean circulation. The discrepancy between the objective analysis and the reanalyses, as well as the spread among the different reanalyses, are used as a simple estimate of ocean state uncertainties. Two robust findings result from this analysis: (1) the signature of anthropogenic changes is qualitatively different from those of the internal decadal variability associated to the Pacific Interdecadal Oscillation and the Atlantic Meridional Oscillation, and (2) the anthropogenic changes in ocean heat content do not only consist of local heat absorption, but are likely related with changes in the ocean circulation, with a clear shallowing of the tropical thermocline in the Pacific and Indian oceans. (orig.)

  6. Variability and predictability of decadal mean temperature and precipitation over China in the CCSM4 last millennium simulation (United States)

    Ying, Kairan; Frederiksen, Carsten S.; Zheng, Xiaogu; Lou, Jiale; Zhao, Tianbao


    The modes of variability that arise from the slow-decadal (potentially predictable) and intra-decadal (unpredictable) components of decadal mean temperature and precipitation over China are examined, in a 1000 year (850-1850 AD) experiment using the CCSM4 model. Solar variations, volcanic aerosols, orbital forcing, land use, and greenhouse gas concentrations provide the main forcing and boundary conditions. The analysis is done using a decadal variance decomposition method that identifies sources of potential decadal predictability and uncertainty. The average potential decadal predictabilities (ratio of slow-to-total decadal variance) are 0.62 and 0.37 for the temperature and rainfall over China, respectively, indicating that the (multi-)decadal variations of temperature are dominated by slow-decadal variability, while precipitation is dominated by unpredictable decadal noise. Possible sources of decadal predictability for the two leading predictable modes of temperature are the external radiative forcing, and the combined effects of slow-decadal variability of the Arctic oscillation (AO) and the Pacific decadal oscillation (PDO), respectively. Combined AO and PDO slow-decadal variability is associated also with the leading predictable mode of precipitation. External radiative forcing as well as the slow-decadal variability of PDO are associated with the second predictable rainfall mode; the slow-decadal variability of Atlantic multi-decadal oscillation (AMO) is associated with the third predictable precipitation mode. The dominant unpredictable decadal modes are associated with intra-decadal/inter-annual phenomena. In particular, the El Niño-Southern Oscillation and the intra-decadal variability of the AMO, PDO and AO are the most important sources of prediction uncertainty.

  7. Sub-seasonal temperature variability in the tropical upper troposphere and lower stratosphere observed with GPS radio occultation (United States)

    Scherllin-Pirscher, Barbara; Randel, William J.; Kim, Joowan


    We investigate sub-seasonal temperature variability in the tropical upper troposphere and lower stratosphere (UTLS) region using daily gridded fields of GPS radio occultation measurements. The unprecedented vertical resolution (from about 100 m in the troposphere to about 1.5 km in the stratosphere) and high accuracy and precision (0.7 K to 1 K between 8 km and 25 km) make these data ideal for characterizing temperature oscillations with short vertical wavelengths. Long-term behavior of sub-seasonal temperature variability is investigated using the entire RO record from January 2002 to December 2014 (13 years of data). Transient sub-seasonal waves including eastward-propagating Kelvin waves (isolated with space-time spectral analysis) dominate large-scale zonal temperature variability in the tropical tropopause region and in the lower stratosphere. Above 20 km, Kelvin waves are strongly modulated by the quasi-biennial oscillation (QBO). Enhanced wave activity can be found during the westerly shear phase of the QBO. In the tropical tropopause region, however, sub-seasonal waves are highly transient in time. Several peaks of Kelvin-wave activity coincide with short-term fluctuations in tropospheric deep convection, but other episodes are not evidently related. Also, there are no obvious relationships with zonal winds or stability fields near the tropical tropopause. Further investigations of convective forcing and atmospheric background conditions along the waves' trajectories are needed to better understand sub-seasonal temperature variability near the tropopause. For more details, see Scherllin-Pirscher, B., Randel, W. J., and Kim, J.: Tropical temperature variability and Kelvin-wave activity in the UTLS from GPS RO measurements, Atmos. Chem. Phys., 17, 793-806, doi:10.5194/acp-17-793-2017, 2017.

  8. Variability of Neuronal Responses: Types and Functional Significance in Neuroplasticity and Neural Darwinism. (United States)

    Chervyakov, Alexander V; Sinitsyn, Dmitry O; Piradov, Michael A


    HIGHLIGHTS We suggest classifying variability of neuronal responses as follows: false (associated with a lack of knowledge about the influential factors), "genuine harmful" (noise), "genuine neutral" (synonyms, repeats), and "genuine useful" (the basis of neuroplasticity and learning).The genuine neutral variability is considered in terms of the phenomenon of degeneracy.Of particular importance is the genuine useful variability that is considered as a potential basis for neuroplasticity and learning. This type of variability is considered in terms of the neural Darwinism theory. In many cases, neural signals detected under the same external experimental conditions significantly change from trial to trial. The variability phenomenon, which complicates extraction of reproducible results and is ignored in many studies by averaging, has attracted attention of researchers in recent years. In this paper, we classify possible types of variability based on its functional significance and describe features of each type. We describe the key adaptive significance of variability at the neural network level and the degeneracy phenomenon that may be important for learning processes in connection with the principle of neuronal group selection.

  9. The circadian rhythm of core body temperature (Part I: The use of modern telemetry systems to monitor core body temperature variability

    Directory of Open Access Journals (Sweden)

    Słomko Joanna


    Full Text Available The best known daily rhythms in humans include: the sleep-wake rhythm, the circadian core body temperature variability, daily fluctuations in arterial blood pressure and heartbeat frequency, and daily changes in hormone secretion: e.g. melatonin, cortisol, growth hormone, prolactin. The core body temperature in humans has a characteristic sinusoidal course, with the maximum value occurring between 3:00-5:00 pm and the minimum between 3:00-5:00 am. Analysis of literature indicates that the obtained results concerning core body temperature are to a large extent influenced by the type of method applied in the measurement. Depending on test protocols, we may apply various methodologies to measuring core body temperature. One of the newest methods of measuring internal and external body temperature consists in the utilisation of remote temperature sensors transmitting the obtained value via a radio signal. The advantages of this method includes the ability to perform: continuous core temperature measurement, observe dynamic changes in core body temperature occurring in circadian rhythm and the repeatability and credibility of the obtained results, which is presented in numerous scientific reports.

  10. Population variability in biological adaptive responses to DNA damage and the shapes of carcinogen dose-response curves

    International Nuclear Information System (INIS)

    Conolly, Rory B.; Gaylor, David W.; Lutz, Werner K.


    Carcinogen dose-response curves for both ionizing radiation and chemicals are typically assumed to be linear at environmentally relevant doses. This assumption is used to ensure protection of the public health in the absence of relevant dose-response data. A theoretical justification for the assumption has been provided by the argument that low dose linearity is expected when an exogenous agent adds to an ongoing endogenous process. Here, we use computational modeling to evaluate (1) how two biological adaptive processes, induction of DNA repair and cell cycle checkpoint control, may affect the shapes of dose-response curves for DNA-damaging carcinogens and (2) how the resulting dose-response behaviors may vary within a population. Each model incorporating an adaptive process was capable of generating not only monotonic dose-responses but also nonmonotonic (J-shaped) and threshold responses. Monte Carlo analysis suggested that all these dose-response behaviors could coexist within a population, as the spectrum of qualitative differences arose from quantitative changes in parameter values. While this analysis is largely theoretical, it suggests that (a) accurate prediction of the qualitative form of the dose-response requires a quantitative understanding of the mechanism (b) significant uncertainty is associated with human health risk prediction in the absence of such quantitative understanding and (c) a stronger experimental and regulatory focus on biological mechanisms and interindividual variability would allow flexibility in regulatory treatment of environmental carcinogens without compromising human health

  11. Impact of instrumental response on observed ozonesonde profiles: First-order estimates and implications for measures of variability (United States)

    Clifton, G. T.; Merrill, J. T.; Johnson, B. J.; Oltmans, S. J.


    Ozonesondes provide information on the ozone distribution up to the middle stratosphere. Ozone profiles often feature layers, with vertically discrete maxima and minima in the mixing ratio. Layers are especially common in the UT/LS regions and originate from wave breaking, shearing and other transport processes. ECC sondes, however, have a moderate response time to significant changes in ozone. A sonde can ascend over 350 meters before it responds fully to a step change in ozone. This results in an overestimate of the altitude assigned to layers and an underestimate of the underlying variability in the amount of ozone. An estimate of the response time is made for each instrument during the preparation for flight, but the profile data are typically not processed to account for the response. Here we present a method of categorizing the response time of ECC instruments and an analysis of a low-pass filter approximation to the effects on profile data. Exponential functions were fit to the step-up and step-down responses using laboratory data. The resulting response time estimates were consistent with results from standard procedures, with the up-step response time exceeding the down-step value somewhat. A single-pole Butterworth filter that approximates the instrumental effect was used with synthetic layered profiles to make first-order estimates of the impact of the finite response time. Using a layer analysis program previously applied to observed profiles we find that instrumental effects can attenuate ozone variability by 20-45% in individual layers, but that the vertical offset in layer altitudes is moderate, up to about 150 meters. We will present results obtained using this approach, coupled with data on the distribution of layer characteristics found using the layer analysis procedure on profiles from Narragansett, Rhode Island and other US sites to quantify the impact on overall variability estimates given ambient distributions of layer occurrence, thickness

  12. Different patterns of transcriptomic response to high temperature ...

    African Journals Online (AJOL)



    Aug 15, 2011 ... The objectives of this study were: (i) to shed light on how genome doubling affects ... for 24 h with the same photoperiod and light intensity as control. After the high temperature ..... in photosynthesis. Photosynth. Res., 98: ...

  13. Physiological and biochemical responses to low temperature stress ...

    African Journals Online (AJOL)

    ajl yemi


    Nov 9, 2011 ... Levels of electrolyte leak and MDA were lower than in UD189 or UD191. Poplar hybrid clones ... humidity, exposure, and water status and health conditions of ... consecutive low temperature treatment; and to detect variation ...

  14. Decline in snowfall in response to temperature in Satluj basin ...

    Indian Academy of Sciences (India)

    The study also consists an analysis of average values of annual snowfall and temperature ... During the study, it was observed that the snowfall exhibited declining trends in the basin. ... National Institute of Hydrology, Roorkee 247 667, India.

  15. Annual to Inter-Decadal Variability in Surface Air Temperature Along ...

    African Journals Online (AJOL)

    instrumental sea surface temperature (SST) and. East African rainfall ... accelerated rise in minimum temperatures. The objectives of the ... Altitude above sea level (m) Urban/Exposed. Tanga. 05.05°S ...... Environmental Report, South Florida.

  16. Grassland Growth in Response to Climate Variability in the Upper Indus Basin, Pakistan

    Directory of Open Access Journals (Sweden)

    Sawaid Abbas


    Full Text Available Grasslands in the upper Indus basin provide a resource base for nomadic livestock grazing which is one of the major traditional livelihood practices in the area. The study presents climate patterns, grassland phenology, productivity and spatio-temporal climate controls on grassland growth using satellite data over the upper Indus basin of the Himalayan region, Pakistan. Phenology and productivity metrics of the grasses were estimated using a combination of derivative and threshold methods applied on fitted seasonal vegetation indices data over the period of 2001–2011. Satellite based rainfall and land surface temperature data are considered as representative explanatory variables to climate variability. The results showed distinct phenology and productivity patterns across four bioclimatic regions: (i humid subtropical region (HSR—late start and early end of season with short length of season and low productivity (ii temperate region (TR—early start and late end of season with higher length of season and moderate productivity (iii sub alpine region (SAR—late start and late end of season with very high length of season and the most productive grasses, and (iv alpine region (AR—late start and early end of season with small length of season and least productive grasses. Grassland productivity is constrained by temperature in the alpine region and by rainfall in the humid sub-tropical region. Spring temperature, winter and summer rainfall has shown significant and varied impact on phenology across different altitudes. The productivity is being influenced by summer and annual rainfall in humid subtropical regions, spring temperature in alpine and sub-alpine regions and both temperature and rainfall are contributing in temperate regions. The results revealing a strong relationship between grassland dynamics and climate variability put forth strong signals for drawing more scientific management of rangelands in the area.

  17. Variability of OH rotational temperatures on time scales from hours to 15 years by kinetic temperature variations, emission layer changes, and non-LTE effects (United States)

    Noll, Stefan


    Rotational temperatures derived from hydroxyl (OH) line emission are frequently used to study atmospheric temperatures at altitudes of about 87 km. While the measurement only requires intensities of a few bright lines of an OH band, the interpretation can be complicated. Ground-based temperatures are averages for the entire, typically 8 km wide emission layer. Variations in the rotational temperature are then caused by changes of the kinetic temperature and the OH emission profile. The latter can also be accompanied by differences in the layer-averaged efficiency of the thermalisation of the OH rotational level populations. Since this especially depends on the frequency of collisions with O_2, which is low at high altitudes, the non-local thermodynamic equilibrium (non-LTE) contribution to the measured temperatures can be significant and variable. In order to understand the impact of the different sources of OH rotational temperature variations from time scales of hours to a solar cycle, we have studied spectra from the astronomical echelle spectrographs X-shooter and UVES located at Cerro Paranal in Chile. While the X-shooter data spanning 3.5 years allowed us to measure temperatures for 25 OH and two O_2 bands, the UVES spectra cover no more than 10 OH bands simultaneously but a period of about 15 years. These data have been complemented by kinetic temperature and OH and O_2 emission profiles from the multi-channel radiometer SABER on the TIMED satellite. Taking the O_2 and SABER kinetic temperatures as reference and considering the different band-dependent emission profiles, we could evaluate the contribution of non-LTE effects to the measured OH rotational temperatures depending on line set, band, and time. Non-LTE contributions are significant for most bands and can exceed 10 K. The amplitudes of their average nocturnal and seasonal variation are of the order of 1 to 2 K.

  18. Interannual variability of Central European mean temperature in January / February and its relation to the large-scale circulation

    International Nuclear Information System (INIS)

    Werner, P.C.; Storch, H. von


    The Central European temperature distribution field, as given by 11 stations (Fanoe, Hamburg, Potsdam, Jena, Frankfurt, Uccle, Hohenpeissenberg, Praha, Wien, Zuerich and Geneve), is analysed with respect to its year-to-year variability. January-February (JF) average temperatures are considered for the interval 1901-80. An Orthogonal Function (EOF) analysis reveals that the JF temperature variability is almost entirely controlled by one EOF with uniform sign. The second EOF represents only 7% of the total variance and describes a north-south gradient. The time coefficient of the first EOF is almost stationary whereas the second pattern describes a slight downward trend at the northern stations and a slight upward trend at the southern stations. The relationship of the temperature field to the large-scale circulation, represented by the North Atlantic/European sea-level pressure (SLP) field, is investigated by means of a Canonical Correlation (CCA) Analysis. Two CCA pairs are identified which account for most of the temperature year-to-year variance and which suggest plausible mechanisms. The CCA pairs fail, however, to consistently link the long-term temperature trends to changes in the large-scale circulation. In the output of a 100-year run with a coupled atmosphere-ocean model (ECHAM1/LSG), the same CCA pairs are found but the strength of the link between Central European temperature and North Atlantic SLP is markedly weaker than in the observed data. (orig.)

  19. Time Scales of the European Surface Air Temperature Variability: The Role of the 7-8 Year Cycle

    Czech Academy of Sciences Publication Activity Database

    Jajcay, Nikola; Hlinka, Jaroslav; Kravtsov, S.; Tsonis, A.A.; Paluš, Milan


    Roč. 43, č. 2 (2016), s. 902-909 ISSN 0094-8276 R&D Projects: GA MŠk LH14001 Institutional support: RVO:67985807 Keywords : 7-8 year cycle * air temperature variability * annual cycle amplitude * cross-scale interactions * seasonality * time scales Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 4.253, year: 2016

  20. Variability of Diurnal Temperature Range During Winter Over Western Himalaya: Range- and Altitude-Wise Study (United States)

    Shekhar, M. S.; Devi, Usha; Dash, S. K.; Singh, G. P.; Singh, Amreek


    The current trends in diurnal temperature range, maximum temperature, minimum temperature, mean temperature, and sun shine hours over different ranges and altitudes of Western Himalaya during winter have been studied. Analysis of 25 years of data shows an increasing trend in diurnal temperature range over all the ranges and altitudes of Western Himalaya during winter, thereby confirming regional warming of the region due to present climate change and global warming. Statistical studies show significant increasing trend in maximum temperature over all the ranges and altitudes of Western Himalaya. Minimum temperature shows significant decreasing trend over Pir Panjal and Shamshawari range and significant increasing trend over higher altitude of Western Himalaya. Similarly, sunshine hours show significant decreasing trend over Karakoram range. There exists strong positive correlation between diurnal temperature range and maximum temperature for all the ranges and altitudes of Western Himalaya. Strong negative correlation exists between diurnal temperature range and minimum temperature over Shamshawari and Great Himalaya range and lower altitude of Western Himalaya. Sunshine hours show strong positive correlation with diurnal temperature range over Pir Panjal and Great Himalaya range and lower and higher altitudes.

  1. Hatching response to temperature along a latitudinal gradient by the fairy shrimp Branchinecta lindahli (Crustacea; Branchiopoda; Anostraca in culture conditions

    Directory of Open Access Journals (Sweden)

    D. Christopher Rogers


    Full Text Available Branchinecta lindahli is a broadly distributed fairy shrimp, reported from a range of temporary wetland habitat types in arid western North America. This species’ eggs hatch after the habitat dries, refills from seasonal rain, and receives a strong cold shock during the winter low temperatures. I studied phenotypic variation in temperature responses in cultures collected from four populations across 8° of latitude with low average temperatures ranging from -8 to 8°C. Time to maturation, mature body size and first clutch size decreased, as temperature increased, with only minor body size variability at mortality, regardless of culture origin. No variation in individual egg size was observed, demonstrating that body size is sacrificed to produce at least a few normal eggs during unfavourable years. Latitudinal variation in hatching temperature demonstrated a pattern of adaptive significance, with some overlap between regional temperature hatching cues.  Phenotypic hatching temperature and growth rate responses may cause genetic segregation, selecting one cohort for warmer, dryer years and one cohort for cooler, wetter years.  Drier year selected cohorts can exploit habitats that have shorter hydroperiods even in wet years. This may lead to population specialisation and speciation by adapting to more extreme habitats

  2. Determination of the dried product resistance variability and its influence on the product temperature in pharmaceutical freeze-drying. (United States)

    Scutellà, Bernadette; Trelea, Ioan Cristian; Bourlès, Erwan; Fonseca, Fernanda; Passot, Stephanie


    During the primary drying step of the freeze-drying process, mass transfer resistance strongly affects the product temperature, and consequently the final product quality. The main objective of this study was to evaluate the variability of the mass transfer resistance resulting from the dried product layer (R p ) in a manufacturing batch of vials, and its potential effect on the product temperature, from data obtained in a pilot scale freeze-dryer. Sublimation experiments were run at -25 °C and 10 Pa using two different freezing protocols: with spontaneous or controlled ice nucleation. Five repetitions of each condition were performed. Global (pressure rise test) and local (gravimetric) methods were applied as complementary approaches to estimate R p . The global method allowed to assess variability of the evolution of R p with the dried layer thickness between different experiments whereas the local method informed about R p variability at a fixed time within the vial batch. A product temperature variability of approximately ±4.4 °C was defined for a product dried layer thickness of 5 mm. The present approach can be used to estimate the risk of failure of the process due to mass transfer variability when designing freeze-drying cycle. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. The responses of microbial temperature relationships to seasonal change and winter warming in a temperate grassland. (United States)

    Birgander, Johanna; Olsson, Pål Axel; Rousk, Johannes


    Microorganisms dominate the decomposition of organic matter and their activities are strongly influenced by temperature. As the carbon (C) flux from soil to the atmosphere due to microbial activity is substantial, understanding temperature relationships of microbial processes is critical. It has been shown that microbial temperature relationships in soil correlate with the climate, and microorganisms in field experiments become more warm-tolerant in response to chronic warming. It is also known that microbial temperature relationships reflect the seasons in aquatic ecosystems, but to date this has not been investigated in soil. Although climate change predictions suggest that temperatures will be mostly affected during winter in temperate ecosystems, no assessments exist of the responses of microbial temperature relationships to winter warming. We investigated the responses of the temperature relationships of bacterial growth, fungal growth, and respiration in a temperate grassland to seasonal change, and to 2 years' winter warming. The warming treatments increased winter soil temperatures by 5-6°C, corresponding to 3°C warming of the mean annual temperature. Microbial temperature relationships and temperature sensitivities (Q 10 ) could be accurately established, but did not respond to winter warming or to seasonal temperature change, despite significant shifts in the microbial community structure. The lack of response to winter warming that we demonstrate, and the strong response to chronic warming treatments previously shown, together suggest that it is the peak annual soil temperature that influences the microbial temperature relationships, and that temperatures during colder seasons will have little impact. Thus, mean annual temperatures are poor predictors for microbial temperature relationships. Instead, the intensity of summer heat-spells in temperate systems is likely to shape the microbial temperature relationships that govern the soil-atmosphere C

  4. Inter-individual variability of stone marten behavioral responses to a highway.

    Directory of Open Access Journals (Sweden)

    Fernando Ascensão

    Full Text Available Efforts to reduce the negative impacts of roads on wildlife may be hindered if individuals within the population vary widely in their responses to roads and mitigation strategies ignore this variability. This knowledge is particularly important for medium-sized carnivores as they are vulnerable to road mortality, while also known to use available road passages (e.g., drainage culverts for safely crossing highways. Our goal in this study was to assess whether this apparently contradictory pattern of high road-kill numbers associated with a regular use of road passages is attributable to the variation in behavioral responses toward the highway between individuals. We investigated the responses of seven radio-tracked stone martens (Martes foina to a highway by measuring their utilization distribution, response turning angles and highway crossing patterns. We compared the observed responses to simulated movement parameterized by the observed space use and movement characteristics of each individual, but naïve to the presence of the highway. Our results suggested that martens demonstrate a diversity of responses to the highway, including attraction, indifference, or avoidance. Martens also varied in their highway crossing patterns, with some crossing repeatedly at the same location (often coincident with highway passages. We suspect that the response variability derives from the individual's familiarity of the landscape, including their awareness of highway passage locations. Because of these variable yet potentially attributable responses, we support the use of exclusionary fencing to guide transient (e.g., dispersers individuals to existing passages to reduce the road-kill risk.

  5. Investigations of different doping concentration of phosphorus and boron into silicon substrate on the variable temperature Raman characteristics (United States)

    Li, Xiaoli; Ding, Kai; Liu, Jian; Gao, Junxuan; Zhang, Weifeng


    Different doped silicon substrates have different device applications and have been used to fabricate solar panels and large scale integrated circuits. The thermal transport in silicon substrates are dominated by lattice vibrations, doping type, and doping concentration. In this paper, a variable-temperature Raman spectroscopic system is applied to record the frequency and linewidth changes of the silicon peak at 520 cm-1 in five chips of silicon substrate with different doping concentration of phosphorus and boron at the 83K to 1473K temperature range. The doping has better heat sensitive to temperature on the frequency shift over the low temperature range from 83K to 300K but on FWHM in high temperature range from 300K to 1473K. The results will be helpful for fundamental study and practical applications of silicon substrates.

  6. Detection and variability of the Congo River plume from satellite derived sea surface temperature, salinity, ocean colour and sea level (United States)

    Hopkins, Jo; Lucas, Marc; Dufau, Claire; Sutton, Marion; Lauret, Olivier


    The Congo River in Africa has the world's second highest annual mean daily freshwater discharge and is the second largest exporter of terrestrial organic carbon into the oceans. It annually discharges an average of 1,250 × 109 m3 of freshwater into the southeast Atlantic producing a vast fresh water plume, whose signature can be traced hundreds of kilometres from the river mouth. Large river plumes such as this play important roles in the ocean carbon cycle, often functioning as carbon sinks. An understanding of their extent and seasonality is therefore essential if they are to be realistically accounted for in global assessments of the carbon cycle. Despite its size, the variability and dynamics of the Congo plume are minimally documented. In this paper we analyse satellite derived sea surface temperature, salinity, ocean colour and sea level anomaly to describe and quantify the extent, strength and variability of the far-field plume and to explain its behaviour in relation to winds, ocean currents and fresh water discharge. Empirical Orthogonal Function analysis reveals strong seasonal and coastal upwelling signals, potential bimodal seasonality of the Angola Current and responses to fresh water discharge peaks in all data sets. The strongest plume-like signatures however were found in the salinity and ocean colour where the dominant sources of variability come from the Congo River itself, rather than from the wider atmosphere and ocean. These two data sets are then analysed using a statistically based water mass detection technique to isolate the behaviour of the plume. The Congo's close proximity to the equator means that the influence of the earth's rotation on the fresh water inflow is relatively small and the plume tends not to form a distinct coastal current. Instead, its behaviour is determined by wind and surface circulation patterns. The main axis of the plume between November and February, following peak river discharge, is oriented northwest, driven

  7. A Delay Time Measurement of ULTRAS (Ultra-high Temperature Ultrasonic Response Analysis System) for a High Temperature Experiment

    International Nuclear Information System (INIS)

    Koo, Kil Mo; Kim, Sang Baik


    The temperature measurement of very high temperature core melt is of importance in a high temperature as the molten pool experiment in which gap formation between core melt and the reactor lower head, and the effect of the gap on thermal behavior are to be measured. The existing temperature measurement techniques have some problems, which the thermocouple, one of the contact methods, is restricted to under 2000 .deg. C, and the infrared thermometry, one of the non-contact methods, is unable to measure an internal temperature and very sensitive to the interference from reacted gases. In order to solve these problems, the delay time technique of ultrasonic wavelets due to high temperature has two sorts of stage. As a first stage, a delay time measurement of ULTRAS (Ultra-high Temperature Ultrasonic Response Analysis System) is suggested. As a second stage, a molten material temperature was measured up to 2300 .deg. C. Also, the optimization design of the UTS (ultrasonic temperature sensor) with persistence at the high temperature was suggested in this paper. And the utilization of the theory suggested in this paper and the efficiency of the developed system are performed by special equipment and some experiments supported by KRISS (Korea Research Institute of Standard and Science)

  8. Eyewitness Accounts on Climate Variability and the Responses: Perspectives from Farmers

    Directory of Open Access Journals (Sweden)

    Jiban Mani Poudel


    Full Text Available People with different socio-cultural arrangements havedifferent experiences and responses to climatic variability. The place specific experiences and responses at community level still remain a little explored issue in the discourse of climate change research. This paper deals with local experiences of climatic variability which have been monitoring by locals in their lifetime, on the one hand, and, on the other, explore their responses or coping mechanisms which they have been practicing to mitigate with climatic risks. Moreover, farmers’ experiences were documented in term of observed climatic variability in their lifetime focusing on qualitative data. I have used eyewitness accounts and hearsays to document their experiences of climatic variability. Moreover, farmers have developed various coping mechanisms such as indigenous knowledge, utilize kinship based social network, environment friendly cropping practices, and use of alternative sources of water (water-tanker, well-water for irrigation, arrange rain-making ritual to cope with climatic uncertainty in their lifetime.DOI: Journal of Sociology and Anthropology Vol. 5, 2011: 171-90

  9. Effect of variability in lighting and temperature environments for mature gilts housed in gestation crates on measures of reproduction and animal well-being. (United States)

    Canaday, D C; Salak-Johnson, J L; Visconti, A M; Wang, X; Bhalerao, K; Knox, R V


    The effects of room temperature and light intensity before breeding and into early gestation were evaluated on the reproductive performance and well-being of gilts housed individually in crates. In eight replicates, estrus was synchronized in mature gilts (n = 198) and after last feeding of Matrix were randomly assigned to a room temperature of 15°C (COLD), 21°C (NEUTRAL), or 30°C (HOT) and a light intensity of 11 (DIM) or 433 (BRIGHT) lx. Estrous detection was performed daily and gilts inseminated twice. Blood samples were collected before and after breeding for determination of immune measures and cortisol concentrations. Gilt ADFI, BW, and body temperature were measured. On d 30 postbreeding, gilts were slaughtered to recover reproductive tracts to evaluate pregnancy and litter characteristics. There were no temperature × light intensity interactions for any response variable. Reproductive measures of follicle development, expression of estrus, ovulation rate, pregnancy rate (83.2%), litter size (14.3 ± 0.5), and fetal measures were not affected by temperature or lighting (P > 0.10). Gilts in COLD (37.6°C) had a lower (P postural changes (P 0.10) of light or interaction with temperature on other immune cells or measures. These results indicate that temperatures in the range of 15 to 30°C or light intensity at 11 to 433 lx do not impact reproduction during the follicular phase and into early gestation for mature gilts housed in gestation crates. However, room temperature does impact physiological, behavioral, and immune responses of mature gilts and should be considered as a potential factor that may influence gilt well-being during the first 30 d postbreeding.

  10. Temperature response to future urbanization and climate change (United States)

    Argüeso, Daniel; Evans, Jason P.; Fita, Lluís; Bormann, Kathryn J.


    This study examines the impact of future urban expansion on local near-surface temperature for Sydney (Australia) using a future climate scenario (A2). The Weather Research and Forecasting model was used to simulate the present (1990-2009) and future (2040-2059) climates of the region at 2-km spatial resolution. The standard land use of the model was replaced with a more accurate dataset that covers the Sydney area. The future simulation incorporates the projected changes in the urban area of Sydney to account for the expected urban expansion. A comparison between areas with projected land use changes and their surroundings was conducted to evaluate how urbanization and global warming will act together and to ascertain their combined effect on the local climate. The analysis of the temperature changes revealed that future urbanization will strongly affect minimum temperature, whereas little impact was detected for maximum temperature. The minimum temperature changes will be noticeable throughout the year. However, during winter and spring these differences will be particularly large and the increases could be double the increase due to global warming alone at 2050. Results indicated that the changes were mostly due to increased heat capacity of urban structures and reduced evaporation in the city environment.

  11. Peanut canopy temperature and NDVI response to varying irrigation rates (United States)

    Variable rate irrigation (VRI) systems have the potential to conserve water by spatially allocating limited water resources. In this study, peanut was grown under a VRI system to evaluate the impact of differential irrigation rates on peanut yield. Additionally, we evaluated the impact of differenti...

  12. Braking System Modeling and Brake Temperature Response to Repeated Cycle

    Directory of Open Access Journals (Sweden)

    Zaini Dalimus


    Full Text Available Braking safety is crucial while driving the passenger or commercial vehicles. Large amount of kinetic energy is absorbed by four brakes fitted in the vehicle. If the braking system fails to work, road accident could happen and may result in death. This research aims to model braking system together with vehicle in Matlab/Simulink software and measure actual brake temperature. First, brake characteristic and vehicle dynamic model were generated to estimate friction force and dissipated heat. Next, Arduino based prototype brake temperature monitoring was developed and tested on the road. From the experiment, it was found that brake temperature tends to increase steadily in long repeated deceleration and acceleration cycle.

  13. Response of birds to climatic variability; evidence from the western fringe of Europe (United States)

    Donnelly, Alison; Cooney, Tom; Jennings, Eleanor; Buscardo, Erika; Jones, Mike


    Ireland’s geographic location on the western fringe of the European continent, together with its island status and impoverished avifauna, provides a unique opportunity to observe changes in bird migration and distribution patterns in response to changing climatic conditions. Spring temperatures have increased in western Europe over the past 30 years in line with reported global warming. These have been shown, at least in part, to be responsible for changes in the timing of life cycle events (phenology) of plants and animals. In order to investigate the response of bird species in Ireland to changes in temperature, we examined ornithological records of trans-Saharan migrants over the 31-year period 1969-1999. Analysis of the data revealed that two discrete climatic phenomena produced different responses in summer migrant bird species. Firstly, a number of long-distance migrants showed a significant trend towards earlier arrival. This trend was evident in some species and was found to be a response to increasing spring air temperature particularly in the month of March. Secondly, (1) a step change in the pattern of occurrences of non-breeding migrant bird species, and (2) an increase in the ringing data of migrant species were found to correlate with a step change in temperature in 1987-1988. These results indicate that, for migrant bird species, the impact of a sudden change in temperature can be as important as any long-term monotonic trend, and we suggest that the impact of step change events merits further investigation on a wider range of species and across a greater geographical range.

  14. Seasonal Canopy Temperatures for Normal and Okra Leaf Cotton under Variable Irrigation in the Field

    Directory of Open Access Journals (Sweden)

    James R. Mahan


    Full Text Available Temperature affects a number of physiological factors in plants and is related to water use, yield and quality in many crop species. Seasonal canopy temperature, measured with infrared thermometers, is often used in conjunction with environmental factors (e.g., air temperature, humidity, solar radiation to assess crop stress and management actions in cotton. Normal and okra leaf shapes in cotton have been associated with differences in water use and canopy temperature. The okra leaf shape in cotton is generally expected to result in lower water use and lower canopy temperatures, relative to normal leaf, under water deficits. In this study canopy temperatures were monitored in okra and normal leaf varieties for a growing season at four irrigation levels. Differences in canopy temperature (<2 °C were measured between the two leaf shapes. As irrigation levels increased, canopy temperature differences between the leaf shapes declined. At the lowest irrigation level, when differences in sensible energy exchanges due to the okra leaf shape would be enhanced, the canopy temperature of the okra leaf was warmer than the normal leaf. This suggests that varietal differences that are not related to leaf shape may have more than compensated for leaf shape differences in the canopy temperature.

  15. Temperature and food-mediated variability of European Atlantic sardine recruitment (United States)

    Garrido, Susana; Silva, Alexandra; Marques, Vitor; Figueiredo, Ivone; Bryère, Philippe; Mangin, Antoine; Santos, A. Miguel P.


    The influence of the environmental conditions during larval development on the resulting recruitment strength was investigated for European sardine (Sardina pilchardus) at Atlanto-Iberian waters. Satellite-derived Sea Surface Temperature (SST) and Chlorophyll-a concentration (Chla) data from the previous spawning seasons (January to March/April and October to December of the previous year) were related to recruitment success data in the main recruitment hotspots. Recruitment data was taken from yearly acoustic scientific cruises and from the ICES recruitment index estimated by an age-structured model for the entire stock. A linear discriminant analysis model using SST, Chla, and the abundance of spawners during the spawning season identified years of high and low recruitment for all the recruitment hotspots with an accuracy of ≥79%. In general, high recruitment years were associated with high Chla and low SST, although the most important variables to discriminate between the groups were area-specific. High recruitment years were mostly related to high food availability (Chla), particularly during the last quarter of the previous year. In Western Iberia and in the Gulf of Cadiz, high recruitment years were also associated to lower SST, whereas in the Bay of Biscay, where SST during the winter was generally below the optimal range ≈11-12 °C for sardine larval development, higher recruitment was associated with high SST. For ICES data of the southern European sardine stock, lower SST and higher Chla during the last quarter of the previous year were associated with high recruitment years and SST alone was able to discriminate between the two recruitment groups with 73% accuracy. Although the time-series of available data are still small, these significant relationships are consistent with field and laboratory studies relating larval growth and mortality with main environmental drivers. These relationships should be further investigated in the following years to

  16. Evaluating infant core temperature response in a hot car using a heat balance model. (United States)

    Grundstein, Andrew J; Duzinski, Sarah V; Dolinak, David; Null, Jan; Iyer, Sujit S


    Using a 1-year old male infant as the model subject, the objectives of this study were to measure increased body temperature of an infant inside an enclosed vehicle during the work day (8:00 am-4:00 pm) during four seasons and model the time to un-compensable heating, heat stroke [>40 °C (>104 °F)], and critical thermal maximum [>42 °C (>107.6 °F)]. A human heat balance model was used to simulate a child's physiological response to extreme heat exposure within an enclosed vehicle. Environmental variables were obtained from the nearest National Weather Service automated surface observing weather station and from an observational vehicular temperature study conducted in Austin, Texas in 2012. In all four seasons, despite differences in starting temperature and solar radiation, the model infant reached heat stroke and demise before 2:00 pm. Time to heat stroke and demise occurred most rapidly in summer, at intermediate durations in fall and spring, and most slowly in the winter. In August, the model infant reached un-compensable heat within 20 min, heat stroke within 105 min, and demise within 125 min. The average rate of heating from un-compensable heat to heat stroke was 1.7 °C/h (3.0 °F/h) and from heat stroke to demise was 4.8 °C/h (8.5 °F/h). Infants left in vehicles during the workday can reach hazardous thermal thresholds quickly even with mild environmental temperatures. These results provide a seasonal analogue of infant heat stroke time course. Further effort is required to create a universally available forensic tool to predict vehicular hyperthermia time course to demise.

  17. Low-frequency variability of surface air temperature over the Barents Sea

    NARCIS (Netherlands)

    Linden, van der Eveline C.; Bintanja, Richard; Hazeleger, Wilco; Graversen, R.G.


    The predominant decadal to multidecadal variability in the Arctic region is a feature that is not yet well-understood. It is shown that the Barents Sea is a key region for Arctic-wide variability. This is an important topic because low-frequency changes in the ocean might lead to large variations

  18. Temperature response of soil respiration largely unaltered with experimental warming

    NARCIS (Netherlands)

    Carey, J.C.; Tang, J.; Templer, P.H.; Kroeger, K.D.; Crowther, T.W.; Burton, A.J.; Dukes, J.S.; Emmett, B.; Frey, S.D.; Heskel, M.A.; Jiang, L.; Machmuller, M.B.; Mohan, J.; Panetta, A.M.; Reich, P.B.; Reinsch, S.; Wang, X.; Allison, S.D.; Bamminger, C.; Bridgham, S.; Collins, S.L.; de Dato, G.; Eddy, W.C.; Enquist, B.J.; Estiarte, M.; Harte, J.; Henderson, A.; Johnson, B.R.; Larsen, K.S.; Luo, Y.; Marhan, S.; Melillo, J.M.; Peñuelas, J.; Pfeifer-Meister, L.; Poll, C.; Rastetter, E.; Reinmann, A.B.; Reynolds, L.L.; Schmidt, I.K.; Shaver, G.R.; Strong, A.L.; Suseela, V.; Tietema, A.


    The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific

  19. Metabolic responses of Eucalyptus species to different temperature regimes

    NARCIS (Netherlands)

    Mokochinski, Joao Benhur; Mazzafera, Paulo; Sawaya, Alexandra Christine Helena Frankland; Mumm, Roland; Vos, de Ric Cornelis Hendricus; Hall, Robert David


    Species and hybrids of Eucalyptus are the world's most widely planted hardwood trees. They are cultivated across a wide range of latitudes and therefore environmental conditions. In this context, comprehensive metabolomics approaches have been used to assess how different temperature regimes may

  20. Adsorption behavior of proteins on temperature-responsive resins

    Czech Academy of Sciences Publication Activity Database

    Poplewska, I.; Muca, R.; Strachota, Adam; Piatkowski, W.; Antos, D.


    Roč. 1324, 10 January (2014), s. 181-189 ISSN 0021-9673 Institutional support: RVO:61389013 Keywords : bioseparations * N-isopropylacrylamide * thermo-responsible resins Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.169, year: 2014

  1. Coupling between marine boundary layer clouds and summer-to-summer sea surface temperature variability over the North Atlantic and Pacific (United States)

    Myers, Timothy A.; Mechoso, Carlos R.; DeFlorio, Michael J.


    Climate modes of variability over the Atlantic and Pacific may be amplified by a positive feedback between sea-surface temperature (SST) and marine boundary layer clouds. However, it is well known that climate models poorly simulate this feedback. Does this deficiency contribute to model-to-model differences in the representation of climate modes of variability? Over both the North Atlantic and Pacific, typical summertime interannual to interdecadal SST variability exhibits horseshoe-like patterns of co-located anomalies of shortwave cloud radiative effect (CRE), low-level cloud fraction, SST, and estimated inversion strength over the subtropics and midlatitudes that are consistent with a positive cloud feedback. During winter over the midlatitudes, this feedback appears to be diminished. Models participating in the Coupled Model Intercomparison Project phase 5 that simulate a weak feedback between subtropical SST and shortwave CRE produce smaller and less realistic amplitudes of summertime SST and CRE variability over the northern oceans compared to models with a stronger feedback. The change in SST amplitude per unit change in CRE amplitude among the models and observations may be understood as the temperature response of the ocean mixed layer to a unit change in radiative flux over the course of a season. These results highlight the importance of boundary layer clouds in interannual to interdecadal atmosphere-ocean variability over the northern oceans during summer. The results also suggest that deficiencies in the simulation of these clouds in coupled climate models contribute to underestimation in their simulation of summer-to-summer SST variability.

  2. Predicting long-term temperature increase for time-dependent SAR levels with a single short-term temperature response. (United States)

    Carluccio, Giuseppe; Bruno, Mary; Collins, Christopher M


    Present a novel method for rapid prediction of temperature in vivo for a series of pulse sequences with differing levels and distributions of specific energy absorption rate (SAR). After the temperature response to a brief period of heating is characterized, a rapid estimate of temperature during a series of periods at different heating levels is made using a linear heat equation and impulse-response (IR) concepts. Here the initial characterization and long-term prediction for a complete spine exam are made with the Pennes' bioheat equation where, at first, core body temperature is allowed to increase and local perfusion is not. Then corrections through time allowing variation in local perfusion are introduced. The fast IR-based method predicted maximum temperature increase within 1% of that with a full finite difference simulation, but required less than 3.5% of the computation time. Even higher accelerations are possible depending on the time step size chosen, with loss in temporal resolution. Correction for temperature-dependent perfusion requires negligible additional time and can be adjusted to be more or less conservative than the corresponding finite difference simulation. With appropriate methods, it is possible to rapidly predict temperature increase throughout the body for actual MR examinations. © 2015 Wiley Periodicals, Inc.

  3. Spatial and temporal variability of rainfall and their effects on hydrological response in urban areas - a review (United States)

    Cristiano, Elena; ten Veldhuis, Marie-claire; van de Giesen, Nick


    In urban areas, hydrological processes are characterized by high variability in space and time, making them sensitive to small-scale temporal and spatial rainfall variability. In the last decades new instruments, techniques, and methods have been developed to capture rainfall and hydrological processes at high resolution. Weather radars have been introduced to estimate high spatial and temporal rainfall variability. At the same time, new models have been proposed to reproduce hydrological response, based on small-scale representation of urban catchment spatial variability. Despite these efforts, interactions between rainfall variability, catchment heterogeneity, and hydrological response remain poorly understood. This paper presents a review of our current understanding of hydrological processes in urban environments as reported in the literature, focusing on their spatial and temporal variability aspects. We review recent findings on the effects of rainfall variability on hydrological response and identify gaps where knowledge needs to be further developed to improve our understanding of and capability to predict urban hydrological response.

  4. Decreased reaction time variability is associated with greater cardiovascular responses to acute stress. (United States)

    Wawrzyniak, Andrew J; Hamer, Mark; Steptoe, Andrew; Endrighi, Romano


    Cardiovascular (CV) responses to mental stress are prospectively associated with poor CV outcomes. The association between CV responses to mental stress and reaction times (RTs) in aging individuals may be important but warrants further investigation. The present study assessed RTs to examine associations with CV responses to mental stress in healthy, older individuals using robust regression techniques. Participants were 262 men and women (mean age = 63.3 ± 5.5 years) from the Whitehall II cohort who completed a RT task (Stroop) and underwent acute mental stress (mirror tracing) to elicit CV responses. Blood pressure, heart rate, and heart rate variability were measured at baseline, during acute stress, and through a 75-min recovery. RT measures were generated from an ex-Gaussian distribution that yielded three predictors: mu-RT, sigma-RT, and tau-RT, the mean, standard deviation, and mean of the exponential component of the normal distribution, respectively. Decreased intraindividual RT variability was marginally associated with greater systolic (B = -.009, SE = .005, p = .09) and diastolic (B = -.004, SE = .002, p = .08) blood pressure reactivity. Decreased intraindividual RT variability was associated with impaired systolic blood pressure recovery (B = -.007, SE = .003, p = .03) and impaired vagal tone (B = -.0047, SE = .0024, p = .045). Study findings offer tentative support for an association between RTs and CV responses. Despite small effect sizes and associations not consistent across predictors, these data may point to a link between intrinsic neuronal plasticity and CV responses. © 2016 The Authors. Psychophysiology published by Wiley Periodicals, Inc. on behalf of Society for Psychophysiological Research.

  5. Colony-specific investigations reveal highly variable responses among individual corals to ocean acidification and warming. (United States)

    Kavousi, Javid; Reimer, James Davis; Tanaka, Yasuaki; Nakamura, Takashi


    As anthropogenic climate change is an ongoing concern, scientific investigations on its impacts on coral reefs are increasing. Although impacts of combined ocean acidification (OA) and temperature stress (T) on reef-building scleractinian corals have been studied at the genus, species and population levels, there are little data available on how individual corals respond to combined OA and anomalous temperatures. In this study, we exposed individual colonies of Acropora digitifera, Montipora digitata and Porites cylindrica to four pCO2-temperature treatments including 400 μatm-28 °C, 400 μatm-31 °C, 1000 μatm-28 °C and 1000 μatm-31 °C for 26 days. Physiological parameters including calcification, protein content, maximum photosynthetic efficiency, Symbiodinium density, and chlorophyll content along with Symbiodinium type of each colony were examined. Along with intercolonial responses, responses of individual colonies versus pooled data to the treatments were investigated. The main results were: 1) responses to either OA or T or their combination were different between individual colonies when considering physiological functions; 2) tolerance to either OA or T was not synonymous with tolerance to the other parameter; 3) tolerance to both OA and T did not necessarily lead to tolerance of OA and T combined (OAT) at the same time; 4) OAT had negative, positive or no impacts on physiological functions of coral colonies; and 5) pooled data were not representative of responses of all individual colonies. Indeed, the pooled data obscured actual responses of individual colonies or presented a response that was not observed in any individual. From the results of this study we recommend improving experimental designs of studies investigating physiological responses of corals to climate change by complementing them with colony-specific examinations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Simulation of uranium transport with variable temperature and oxidation potential: The computer program THCC [Thermo-Hydro-Chemical Coupling

    International Nuclear Information System (INIS)

    Carnahan, C.L.


    A simulator of reactive chemical transport has been constructed with the capabilities of treating variable temperatures and variable oxidation potentials within a single simulation. Homogeneous and heterogeneous chemical reactions are simulated at temperature-dependent equilibrium, and changes of oxidation states of multivalent elements can be simulated during transport. Chemical mass action relations for formation of complexes in the fluid phase are included explicitly within the partial differential equations of transport, and a special algorithm greatly simplifies treatment of reversible precipitation of solid phases. This approach allows direct solution of the complete set of governing equations for concentrations of all aqueous species and solids affected simultaneously by chemical and physical processes. Results of example simulations of transport, along a temperature gradient, of uranium solution species under conditions of varying pH and oxidation potential and with reversible precipitation of uraninite and coffinite are presented. The examples illustrate how inclusion of variable temperature and oxidation potential in numerical simulators can enhance understanding of the chemical mechanisms affecting migration of multivalent waste elements

  7. ltm: An R Package for Latent Variable Modeling and Item Response Analysis

    Directory of Open Access Journals (Sweden)

    Dimitris Rizopoulos


    Full Text Available The R package ltm has been developed for the analysis of multivariate dichotomous and polytomous data using latent variable models, under the Item Response Theory approach. For dichotomous data the Rasch, the Two-Parameter Logistic, and Birnbaum's Three-Parameter models have been implemented, whereas for polytomous data Semejima's Graded Response model is available. Parameter estimates are obtained under marginal maximum likelihood using the Gauss-Hermite quadrature rule. The capabilities and features of the package are illustrated using two real data examples.

  8. Strong increase in convective precipitation in response to higher temperatures

    DEFF Research Database (Denmark)

    Berg, P.; Moseley, C.; Härter, Jan Olaf Mirko


    Precipitation changes can affect society more directly than variations in most other meteorological observables, but precipitation is difficult to characterize because of fluctuations on nearly all temporal and spatial scales. In addition, the intensity of extreme precipitation rises markedly...... at higher temperature, faster than the rate of increase in the atmosphere's water-holding capacity, termed the Clausius-Clapeyron rate. Invigoration of convective precipitation (such as thunderstorms) has been favoured over a rise in stratiform precipitation (such as large-scale frontal precipitation......) as a cause for this increase , but the relative contributions of these two types of precipitation have been difficult to disentangle. Here we combine large data sets from radar measurements and rain gauges over Germany with corresponding synoptic observations and temperature records, and separate convective...

  9. A new variable temperature solution-solid interface scanning tunneling microscope. (United States)

    Jahanbekam, Abdolreza; Mazur, Ursula; Hipps, K W


    We present a new solution-solid (SS) interface scanning tunneling microscope design that enables imaging at high temperatures with low thermal drift and with volatile solvents. In this new design, distinct from the conventional designs, the entire microscope is surrounded in a controlled-temperature and controlled-atmosphere chamber. This allows users to take measurements at high temperatures while minimizing thermal drift. By incorporating an open solution reservoir in the chamber, solvent evaporation from the sample is minimized; allowing users to use volatile solvents for temperature dependent studies at high temperatures. The new design enables the user to image at the SS interface with some volatile solvents for long periods of time (>24 h). An increase in the nonlinearity of the piezoelectric scanner in the lateral direction as a function of temperature is addressed. A temperature dependent study of cobalt(II) octaethylporphyrin (CoOEP) at the toluene/Au(111) interface has been performed with this instrument. It is demonstrated that the lattice parameters remain constant within experimental error from 24 °C to 75 °C. Similar quality images were obtained over the entire temperature range. We report the unit cell of CoOEP at the toluene/Au(111) interface (based on two molecules per unit cell) to be A = (1.36 ± 0.04) nm, B = (2.51 ± 0.04) nm, and α = 97° ± 2°.

  10. Temperature-Phase Converter Based on a LC Cell as a Variable Capacitance

    Directory of Open Access Journals (Sweden)

    Juan Carlos Torres


    Full Text Available The main characteristic of liquid crystals is that their properties, both electrical and optical, can be modified through a convenient applied signal, for instance a certain voltage. This tunable behavior of liquid crystals is directly related to the orientation of their nanometric components with respect to a director direction. However, the initial alignment is a fabrication-dependent parameter and may be either planar or homeotropic. In addition, the strong dependence of the properties of liquid crystals with the temperature is well known and widely used for several temperature sensors. This dependence is produced by the influence of the temperature on the ordering of the molecules. In this work, we have studied the temperature dependence of the electric properties of a liquid crystal cell, in particular the dielectric permittivity, with the temperature as a function of the initial alignment set during the fabrication process. Starting from experimental measurements, an equivalent circuit model including the temperature dependence has been proposed. We have observed that a good linearity in a wide temperature range is provided at a suitable exciting frequency. Finally, a proper conditioner circuit is proposed as a powerful tool for linear and high sensibility temperature measurement.

  11. Response variability of different anodal transcranial direct current stimulation intensities across multiple sessions. (United States)

    Ammann, Claudia; Lindquist, Martin A; Celnik, Pablo A

    It is well known that transcranial direct current stimulation (tDCS) is capable of modulating corticomotor excitability. However, a source of growing concern has been the observed inter- and intra-individual variability of tDCS-responses. Recent studies have assessed whether individuals respond in a predictable manner across repeated sessions of anodal tDCS (atDCS). The findings of these investigations have been inconsistent, and their methods have some limitations (i.e. lack of sham condition or testing only one tDCS intensity). To study inter- and intra-individual variability of atDCS effects at two different intensities on primary motor cortex (M1) excitability. Twelve subjects participated in a crossover study testing 7-min atDCS over M1 in three separate conditions (2 mA, 1 mA, sham) each repeated three times separated by 48 h. Motor evoked potentials were recorded before and after stimulation (up to 30min). Time of testing was maintained consistent within participants. To estimate the reliability of tDCS effects across sessions, we calculated the Intra-class Correlation Coefficient (ICC). AtDCS at 2 mA, but not 1 mA, significantly increased cortical excitability at the group level in all sessions. The overall ICC revealed fair to high reliability of tDCS effects for multiple sessions. Given that the distribution of responses showed important variability in the sham condition, we established a Sham Variability-Based Threshold to classify responses and to track individual changes across sessions. Using this threshold an intra-individual consistent response pattern was then observed only for the 2 mA condition. 2 mA anodal tDCS results in consistent intra- and inter-individual increases of M1 excitability. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. The underestimated role of temperature-oxygen relationship in large-scale studies on size-to-temperature response. (United States)

    Walczyńska, Aleksandra; Sobczyk, Łukasz


    The observation that ectotherm size decreases with increasing temperature (temperature-size rule; TSR) has been widely supported. This phenomenon intrigues researchers because neither its adaptive role nor the conditions under which it is realized are well defined. In light of recent theoretical and empirical studies, oxygen availability is an important candidate for understanding the adaptive role behind TSR. However, this hypothesis is still undervalued in TSR studies at the geographical level. We reanalyzed previously published data about the TSR pattern in diatoms sampled from Icelandic geothermal streams, which concluded that diatoms were an exception to the TSR. Our goal was to incorporate oxygen as a factor in the analysis and to examine whether this approach would change the results. Specifically, we expected that the strength of size response to cold temperatures would be different than the strength of response to hot temperatures, where the oxygen limitation is strongest. By conducting a regression analysis for size response at the community level, we found that diatoms from cold, well-oxygenated streams showed no size-to-temperature response, those from intermediate temperature and oxygen conditions showed reverse TSR, and diatoms from warm, poorly oxygenated streams showed significant TSR. We also distinguished the roles of oxygen and nutrition in TSR. Oxygen is a driving factor, while nutrition is an important factor that should be controlled for. Our results show that if the geographical or global patterns of TSR are to be understood, oxygen should be included in the studies. This argument is important especially for predicting the size response of ectotherms facing climate warming.

  13. Mass Market Demand Response and Variable Generation Integration Issues: A Scoping Study

    Energy Technology Data Exchange (ETDEWEB)

    Cappers, Peter; Mills, Andrew; Goldman, Charles; Wiser, Ryan; Eto, Joseph H.


    This scoping study focuses on the policy issues inherent in the claims made by some Smart Grid proponents that the demand response potential of mass market customers which is enabled by widespread implementation of Advanced Metering Infrastructure (AMI) through the Smart Grid could be the “silver bullet” for mitigating variable generation integration issues. In terms of approach, we will: identify key issues associated with integrating large amounts of variable generation into the bulk power system; identify demand response opportunities made more readily available to mass market customers through widespread deployment of AMI systems and how they can affect the bulk power system; assess the extent to which these mass market Demand Response (DR) opportunities can mitigate Variable Generation (VG) integration issues in the near-term and what electricity market structures and regulatory practices could be changed to further expand the ability for DR to mitigate VG integration issues over the long term; and provide a qualitative comparison of DR and other approaches to mitigate VG integration issues.

  14. Genetic variability induction in the size of the size of rice plantules by combined irradiation and temperature treatments

    International Nuclear Information System (INIS)

    Garcia, D.; Gonzalez, L.M.; Gumberra, R.


    Induced variability in the size of rice plantules was determined using the heritability calculation in a narrow sense, by means of the progenitor-descendant regression. Progenitor stands for the original variety, whereas descendant stands for plant population from CO6 0 gamma-rays irradiated seeds (at 100-600 Gy doses), treated at different temperatures. Results obtained: show the possibility to increase efficiency in variability induction by a combined course of action of both factors. In this experience, the best combination turned out to be 300 Gy-0 celsius grated, which of all the changes that it caused, some 75 percent was of a genetic nature

  15. Evaluation of random temperature fluctuation problems with frequency response approach

    International Nuclear Information System (INIS)

    Lejeail, Yves; Kasahara, Naoto


    Since thermal striping is a coupled thermohydraulic and thermomechanical phenomenon, sodium mock-up tests were usually required to confirm structural integrity. Authors have developed the frequency response function to establish design-by-analysis methodology for this phenomenon. Applicability of this method to sinusoidal fluctuation was validated through two benchmark problems with FAENA and TIFFSS facilities under EJCC contract. This report describes the extension of the frequency response method to random fluctuations. As an example of application, fatigue strength of a Tee junction of PHENIX secondary piping system was investigated. (author)

  16. Drought is Coming: Monitoring Vegetation Response to Water Scarcity through Variable Chlorophyll a Fluorescence (United States)

    Guadagno, C. R.; Beverly, D.; Pleban, J. R.; Speckman, H. N.; Ewers, B. E.; Weinig, C.


    Aridity is one of the most pronounced environmental limits to plant survival, and understanding how plants respond to drought and recovery is crucial for predicting impacts on managed and natural ecosystems. Changes in soil moisture conditions induce a suite of physiological responses from the cell to ecosystem scale, complicating the assessment of drought effects. Characterizing early indicators of water scarcity across species can inform biophysical models with improved understanding of plant hydraulics. While indexes exist for drought monitoring across scales, many are unable to identify imminent vegetative drought. We explore a method of early diagnosis using leaf-level and kinetic imaging measures of variable chlorophyll a fluorescence. This is a fast and reliable tool capturing leaf physiological changes in advance of changes in NDVI or passive solar induced fluorescence. Both image and leaf level Pulse Amplitude Method (PAM) measurements illustrate the utility of variable chlorophyll a fluorescence for monitoring vegetative drought. Variable fluorescence was monitored across populations of crops, desert shrubs, montane conifers and riparian deciduous trees under variable water regimes. We found a strong correlation (R = 0.85) between the maximum efficiency of photosystem II measured using variable fluorescence (Fv'Fm') and leaf level electrolyte leakage, a proximal cause of drought stress induced by cellular damage in leaves. This association was confirmed in two gymnosperm species (Picea engelmannii and Pinus contorta) and for diverse varieties of the crop species Brassica rapa. The use of chlorophyll a fluorescence per image also allowed for early detection of drought in aspen (Populus tremuloides). These results provide evidence that variable chlorophyll fluorescence decreases between 25% and 70% in mild and severely droughted twigs with respect to ones collected from trees in wet soil conditions. While current systems for monitoring variable fluorescence

  17. Temperature dependence of the Al2O3:C response in medical luminescence dosimetry

    DEFF Research Database (Denmark)

    Edmund, Jens Morgenthaler; Andersen, Claus Erik


    is not varied. The RL response only depends on the irradiation temperature. We recommend that calibration should be carried out at the same irradiation temperature at which the measurement is performed (i.e. at body temperature for in vivo measurements). The overall change in the integrated OSL and RL signals...... and detection wavelengths. The reported temperature dependence seems to be a general property of Al2O3:C. (C) 2006 Elsevier Ltd. All rights reserved....

  18. Temperature-dependent stress response in oysters, Crassostrea virginica: Pollution reduces temperature tolerance in oysters

    International Nuclear Information System (INIS)

    Lannig, Gisela; Flores, Jason F.; Sokolova, Inna M.


    Combined effects of temperature and a toxic metal, cadmium (Cd), on energy metabolism were studied in a model marine bivalve, the eastern oyster Crassostrea virginica, acclimated at 20, 24 and 28 deg. C and exposed to 50 μg l -1 of Cd. Both increasing temperature and Cd exposure led to a rise in standard metabolic rates, and combined stressors appeared to override the capability for aerobic energy production resulting in impaired stress tolerance. Oysters exposed to elevated temperature but not Cd showed no significant change in condition, survival rate and lipid peroxidation, whereas those exposed to both Cd and temperature stress suffered high mortality accompanied by low condition index and elevated lipid peroxidation. Furthermore, RNA/DNA ratios indicative of protein synthesis rate, and levels of glutathione, which is involved in metal detoxification, increased in Cd-exposed oysters at 20 deg. C but not at 28 deg. C. Implications of the synergism between elevated temperatures and cadmium stress on energy metabolism of oysters are discussed in the light of the potential effects of climate change on oyster populations in polluted areas

  19. Gene expression in response to Cotton Leaf Curl Virus infection in Gossypium hirsutum under variable environmental conditions

    Directory of Open Access Journals (Sweden)

    Rehman Iqra


    Full Text Available Cotton Leaf Curl Disease (CLCuD is one of the threatening constrains of cotton production in Pakistan for which no adequate remedy is available until now. Local variety of Gossypium hirsutum (FH-142 was grown in field and infected naturally by CLCuV under variable range of temperature and humidity. Plants showed thickening of veins in lower leaf surface at 34°C and 60% relative humidity at 15days post infection (dpi and curling of leaf margins at 33°C with 58% relative humidity at 30dpi. Remarkable leaf darkening was observed with reduced boll formation at 45dpi at 26°C and 41% relative humidity. Enation developed, severe thickening and curling of leaves intensified and plants showed dwarf growth at 60dpi at 24°C with 52% relative humidity. PCR amplification of Rep associated gene confirmed the presence of CLCuD-associated begomovirus in the infected samples. Quantitative RT-PCR confirmed the amplification and differential expression of a number of pathogen stress responsive genes at different levels of temperature and humidity. This observation predicts that Cotton Leaf Curl Virus (CLCuV interacts with several host genes that are upregulated to make plants susceptible or suppress other genes to overcome host defense responses.

  20. Thermal comfort, physiological responses and performance during exposure to a moderate temperature drift

    DEFF Research Database (Denmark)

    Schellen, Lisje; van Marken Lichtenbelt, Wouter; de Wit, Martin


    The objective of this research was to study the effects of a moderate temperature drift on human thermal comfort, physiological responses, productivity and performance. A dynamic thermophysiological model was used to examine the possibility of simulating human thermal responses and thermal comfort...... temperature corresponding with a neutral thermal sensation (control situation). During the experiments both physiological responses and thermal sensation were measured. Productivity and performance were assessed with a ‘Remote Performance Measurement’ (RPM) method. Physiological and thermal sensation data...

  1. The response of archaeal species to seasonal variables in a subtropical aerated soil: insight into the low abundant methanogens. (United States)

    Xie, Wei; Jiao, Na; Ma, Cenling; Fang, Sa; Phelps, Tommy J; Zhu, Ruixin; Zhang, Chuanlun


    Archaea are cosmopolitan in aerated soils around the world. While the dominance of Thaumarchaeota has been reported in most soils, the methanogens are recently found to be ubiquitous but with low abundances in the aerated soil globally. However, the seasonal changes of Archaea community in the aerated soils are still in the mist. In this study, we investigated the change of Archaea in the context of environmental variables over a period of 12 months in a subtropical soil on the Chongming Island, China. The results showed that Nitrososphaera spp. were the dominant archaeal population while the methanogens were in low proportions but highly diverse (including five genera: Methanobacterium, Methanocella, Methanosaeta, Methanosarcina, and Methanomassiliicoccus) in the aerated soil samples determined by high throughput sequencing. A total of 126 LSA correlations were found in the dataset including all the 72 archaeal OTUs and 8 environmental factors. A significance index defined as the pagerank score of each OTU divided by its relative abundance was used to evaluate the significance of each OTU. The results showed that five out of 17 methanogen OTUs were significantly positively correlated with temperature, suggesting those methanogens might increase with temperature rather than being dormant in the aerated soils. Given the metabolic response of methanogens to temperature under aerated soil conditions, their contribution to the global methane cycle warrants evaluation.

  2. DOG1-imposed dormancy mediates germination responses to temperature cues

    NARCIS (Netherlands)

    Murphey, M.; Kovach, K.; Elnacash, T.; He, H.; Bentsink, L.; Donohue, K.


    Seed dormancy and environment-dependent germination requirements interact to determine the timing of germination in natural environments. This study tested the contribution of the dormancy gene Delay Of Germination 1 (DOG1) to primary and secondary dormancy induction in response to environmental

  3. Decline in snowfall in response to temperature in Satluj basin ...

    Indian Academy of Sciences (India)

    Snow is an essential resource present in the Himalaya. ... essential for the development of ecosystems, human ... and stability of the air mass) that influence snow ... better management of agriculture, irrigation, .... the present basin, which is measured by melting ...... response of vegetation to environmental change at high.

  4. A novel smart rotor support with shape memory alloy metal rubber for high temperatures and variable amplitude vibrations

    International Nuclear Information System (INIS)

    Ma, Yanhong; Zhang, Qicheng; Zhang, Dayi; Hong, Jie; Scarpa, Fabrizio; Liu, Baolong


    The work describes the design, manufacturing and testing of a smart rotor support with shape memory alloy metal rubber (SMA-MR) elements, able to provide variable stiffness and damping characteristics with temperature, motion amplitude and excitation frequency. Differences in damping behavior and nonlinear stiffness between SMA-MR and more traditional metal rubber supports are discussed. The mechanical performance shown by the prototype demonstrates the feasibility of using the SMA-MR concept for active vibration control in rotordynamics, in particular at high temperatures and large amplitude vibrations. (paper)

  5. The Role of Microbial Community Composition in Controlling Soil Respiration Responses to Temperature. (United States)

    Auffret, Marc D; Karhu, Kristiina; Khachane, Amit; Dungait, Jennifer A J; Fraser, Fiona; Hopkins, David W; Wookey, Philip A; Singh, Brajesh K; Freitag, Thomas E; Hartley, Iain P; Prosser, James I


    Rising global temperatures may increase the rates of soil organic matter decomposition by heterotrophic microorganisms, potentially accelerating climate change further by releasing additional carbon dioxide (CO2) to the atmosphere. However, the possibility that microbial community responses to prolonged warming may modify the temperature sensitivity of soil respiration creates large uncertainty in the strength of this positive feedback. Both compensatory responses (decreasing temperature sensitivity of soil respiration in the long-term) and enhancing responses (increasing temperature sensitivity) have been reported, but the mechanisms underlying these responses are poorly understood. In this study, microbial biomass, community structure and the activities of dehydrogenase and β-glucosidase enzymes were determined for 18 soils that had previously demonstrated either no response or varying magnitude of enhancing or compensatory responses of temperature sensitivity of heterotrophic microbial respiration to prolonged cooling. The soil cooling approach, in contrast to warming experiments, discriminates between microbial community responses and the consequences of substrate depletion, by minimising changes in substrate availability. The initial microbial community composition, determined by molecular analysis of soils showing contrasting respiration responses to cooling, provided evidence that the magnitude of enhancing responses was partly related to microbial community composition. There was also evidence that higher relative abundance of saprophytic Basidiomycota may explain the compensatory response observed in one soil, but neither microbial biomass nor enzymatic capacity were significantly affected by cooling. Our findings emphasise the key importance of soil microbial community responses for feedbacks to global change, but also highlight important areas where our understanding remains limited.

  6. Proteomic responses to elevated ocean temperature in ovaries of the ascidian Ciona intestinalis

    Directory of Open Access Journals (Sweden)

    Chelsea E. Lopez


    Full Text Available Ciona intestinalis, a common sea squirt, exhibits lower reproductive success at the upper extreme of the water temperatures it experiences in coastal New England. In order to understand the changes in protein expression associated with elevated temperatures, and possible response to global temperature change, we reared C. intestinalis from embryos to adults at 18°C (a temperature at which they reproduce normally at our collection site in Rhode Island and 22°C (the upper end of the local temperature range. We then dissected ovaries from animals at each temperature, extracted protein, and measured proteomic levels using shotgun mass spectrometry (LC-MS/MS. 1532 proteins were detected at a 1% false discovery rate present in both temperature groups by our LC-MS/MS method. 62 of those proteins are considered up- or down-regulated according to our statistical criteria. Principal component analysis shows a clear distinction in protein expression pattern between the control (18°C group and high temperature (22°C group. Similar to previous studies, cytoskeletal and chaperone proteins are upregulated in the high temperature group. Unexpectedly, we find evidence that proteolysis is downregulated at the higher temperature. We propose a working model for the high temperature response in C. intestinalis ovaries whereby increased temperature induces upregulation of signal transduction pathways involving PTPN11 and CrkL, and activating coordinated changes in the proteome especially in large lipid transport proteins, cellular stress responses, cytoskeleton, and downregulation of energy metabolism.

  7. Study on dynamic behavior of fusion reactor materials and their response to variable and complex irradiation environment

    International Nuclear Information System (INIS)

    Abe, K.; Kohyama, A.; Namba, C.; Wiffen, F.W.; Jones, R.H.


    A Japan-USA Program of irradiation experiments for fusion research, 'JUPITER', has been established as a 6 year program from 1995 to 2000. The goal is to study the dynamic behavior of fusion reactor materials and their response to variable and complex irradiation environment using fission reactors. The irradiation experiments in this program include low activation structural materials, functional ceramics and other innovative materials. The experimental data are analyzed by theoretical modeling and computer simulation to integrate the above effects. The irradiation capsules for in-situ measurement and varying temperature were developed successfully. It was found that insulating ceramics were worked up to 3 dpa. The property changes and related issues in low activation structural materials were summarized. (author)

  8. Temporal variability in Cu speciation, phytotoxicity, and soil microbial activity of Cu-polluted soils as affected by elevated temperature. (United States)

    Fu, Qing-Long; Weng, Nanyan; Fujii, Manabu; Zhou, Dong-Mei


    Global warming has obtained increasing attentions due to its multiple impacts on agro-ecosystem. However, limited efforts had been devoted to reveal the temporal variability of metal speciation and phytotoxicity of heavy metal-polluted soils affected by elevated temperature under the global warming scenario. In this study, effects of elevated temperature (15 °C, 25 °C, and 35 °C) on the physicochemical properties, microbial metabolic activities, and phytotoxicity of three Cu-polluted soils were investigated by a laboratory incubation study. Soil physicochemical properties were observed to be significantly altered by elevated temperature with the degree of temperature effect varying in soil types and incubation time. The Biolog and enzymatic tests demonstrated that soil microbial activities were mainly controlled and decreased with increasing incubation temperature. Moreover, plant assays confirmed that the phytotoxicity and Cu uptake by wheat roots were highly dependent on soil types but less affected by incubation temperature. Overall, the findings in this study have highlighted the importance of soil types to better understand the temperature-dependent alternation of soil properties, Cu speciation and bioavailability, as well as phytotoxicity of Cu-polluted soils under global warming scenario. The present study also suggests the necessary of investigating effects of soil types on the transport and accumulation of toxic elements in soil-crop systems under global warming scenario. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Behavioral variability, elimination of responses, and delay-of-reinforcement gradients in SHR and WKY rats

    Directory of Open Access Journals (Sweden)

    Killeen Peter R


    Full Text Available Abstract Background Attention-deficit/hyperactivity disorder (ADHD is characterized by a pattern of inattention, hyperactivity, and impulsivity that is cross-situational, persistent, and produces social and academic impairment. Research has shown that reinforcement processes are altered in ADHD. The dynamic developmental theory has suggested that a steepened delay-of-reinforcement gradient and deficient extinction of behavior produce behavioral symptoms of ADHD and increased behavioral variability. Method The present study investigated behavioral variability and elimination of non-target responses during acquisition in an animal model of ADHD, the spontaneously hypertensive rat (SHR, using Wistar Kyoto (WKY rats as controls. The study also aimed at providing a novel approach to measuring delay-of-reinforcement gradients in the SHR and the WKY strains. The animals were tested in a modified operant chamber presenting 20 response alternatives. Nose pokes in a target hole produced water according to fixed interval (FI schedules of reinforcement, while nose pokes in the remaining 19 holes either had no consequences or produced a sound or a short flickering of the houselight. The stimulus-producing holes were included to test whether light and sound act as sensory reinforcers in SHR. Data from the first six sessions testing FI 1 s were used for calculation of the initial distribution of responses. Additionally, Euclidean distance (measured from the center of each hole to the center of the target hole and entropy (a measure of variability were also calculated. Delay-of-reinforcement gradients were calculated across sessions by dividing the fixed interval into epochs and determining how much reinforcement of responses in one epoch contributed to responding in the next interval. Results Over the initial six sessions, behavior became clustered around the target hole. There was greater initial variability in SHR behavior, and slower elimination of

  10. European seasonal and annual temperature variability, trends, and extremes since 1500. (United States)

    Luterbacher, Jürg; Dietrich, Daniel; Xoplaki, Elena; Grosjean, Martin; Wanner, Heinz


    Multiproxy reconstructions of monthly and seasonal surface temperature fields for Europe back to 1500 show that the late 20th- and early 21st-century European climate is very likely (>95% confidence level) warmer than that of any time during the past 500 years. This agrees with findings for the entire Northern Hemisphere. European winter average temperatures during the period 1500 to 1900 were reduced by approximately 0.5 degrees C (0.25 degrees C for annual mean temperatures) compared to the 20th century. Summer temperatures did not experience systematic century-scale cooling relative to present conditions. The coldest European winter was 1708/1709; 2003 was by far the hottest summer.

  11. Semiarid watershed response in central New Mexico and its sensitivity to climate variability and change

    Directory of Open Access Journals (Sweden)

    E. R. Vivoni


    Full Text Available Hydrologic processes in the semiarid regions of the Southwest United States are considered to be highly susceptible to variations in temperature and precipitation characteristics due to the effects of climate change. Relatively little is known about the potential impacts of climate change on the basin hydrologic response, namely streamflow, evapotranspiration and recharge, in the region. In this study, we present the development and application of a continuous, semi-distributed watershed model for climate change studies in semiarid basins of the Southwest US. Our objective is to capture hydrologic processes in large watersheds, while accounting for the spatial and temporal variations of climate forcing and basin properties in a simple fashion. We apply the model to the Río Salado basin in central New Mexico since it exhibits both a winter and summer precipitation regime and has a historical streamflow record for model testing purposes. Subsequently, we use a sequence of climate change scenarios that capture observed trends for winter and summer precipitation, as well as their interaction with higher temperatures, to perform long-term ensemble simulations of the basin response. Results of the modeling exercise indicate that precipitation uncertainty is amplified in the hydrologic response, in particular for processes that depend on a soil saturation threshold. We obtained substantially different hydrologic sensitivities for winter and summer precipitation ensembles, indicating a greater sensitivity to more intense summer storms as compared to more frequent winter events. In addition, the impact of changes in precipitation characteristics overwhelmed the effects of increased temperature in the study basin. Nevertheless, combined trends in precipitation and temperature yield a more sensitive hydrologic response throughout the year.

  12. Light induced intraspecific variability in response to thermal stress in the hard coral Stylophora pistillata

    Directory of Open Access Journals (Sweden)

    Arjen Tilstra


    Full Text Available Recent research suggests that prior exposure of several months to elevated irradiance induces enhanced thermal tolerance in scleractinian corals. While this tolerance has been reported at the species level, individual coral colonies may react differently due to individual variability in thermal tolerance. As thermal anomalies are predicted to become common in the upcoming future, intraspecific variation may be key to the survival of coral populations. In order to study light-history based thermal stress responses on individual colonies, we developed a preliminary microcosm experiment where three randomly chosen, aquacultured colonies of the model coral Stylophora pistillata were exposed to two irradiance treatments (200 and 400 μmol photons m−2 s−1 for 31 days, followed by artificially induced heat stress (∼33.4 °C. We found different responses to occur at both the intraspecific and the intracolonial levels, as indicated by either equal, less severe, delayed, and/or even non-necrotic responses of corals previously exposed to the irradiance of 400 compared to 200 μmol photons m−2 s−1. In addition, all individual colonies revealed light-enhanced calcification. Finally, elevated irradiance resulted in a lower chlorophyll a concentration in one colony compared to the control treatment, and the same colony displayed more rapid bleaching compared to the other ones. Taken together, this study highlights the potential importance of intra-individual variability in physiological responses of scleractinian corals and provides recommendations for improving methodological designs for future studies.

  13. Variable postpartum responsiveness among humans and other primates with "cooperative breeding": A comparative and evolutionary perspective. (United States)

    Hrdy, Sarah B


    This article is part of a Special Issue "Parental Care".Until recently, evolutionists reconstructing mother-infant bonding among human ancestors relied on nonhuman primate models characterized by exclusively maternal care, overlooking the highly variable responsiveness exhibited by mothers in species with obligate reliance on allomaternal care and provisioning. It is now increasingly recognized that apes as large-brained, slow maturing, and nutritionally dependent for so long as early humans were, could not have evolved unless "alloparents" (group members other than genetic parents), in addition to parents, had helped mothers to care for and provision offspring, a rearing system known as "cooperative breeding." Here I review situation-dependent maternal responses ranging from highly possessive to permissive, temporarily distancing, rejecting, or infanticidal, documented for a small subset of cooperatively breeding primates. As in many mammals, primate maternal responsiveness is influenced by physical condition, endocrinological priming, prior experience and local environments (especially related to security). But mothers among primates who evolved as cooperative breeders also appear unusually sensitive to cues of social support. In addition to more "sapient" or rational decision-making, humankind's deep history of cooperative breeding must be considered when trying to understand the extremely variable responsiveness of human mothers. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Temporal Variability in Vertical Groundwater Fluxes and the Effect of Solar Radiation on Streambed Temperatures Based on Vertical High Resolution Distributed Temperature Sensing (United States)

    Sebok, E.; Karan, S.; Engesgaard, P. K.; Duque, C.


    Due to its large spatial and temporal variability, groundwater discharge to streams is difficult to quantify. Methods using vertical streambed temperature profiles to estimate vertical fluxes are often of coarse vertical spatial resolution and neglect to account for the natural heterogeneity in thermal conductivity of streambed sediments. Here we report on a field investigation in a stream, where air, stream water and streambed sediment temperatures were measured by Distributed Temperature Sensing (DTS) with high spatial resolution to; (i) detect spatial and temporal variability in groundwater discharge based on vertical streambed temperature profiles, (ii) study the thermal regime of streambed sediments exposed to different solar radiation influence, (iii) describe the effect of solar radiation on the measured streambed temperatures. The study was carried out at a field site located along Holtum stream, in Western Denmark. The 3 m wide stream has a sandy streambed with a cobbled armour layer, a mean discharge of 200 l/s and a mean depth of 0.3 m. Streambed temperatures were measured with a high-resolution DTS system (HR-DTS). By helically wrapping the fiber optic cable around two PVC pipes of 0.05 m and 0.075 m outer diameter over 1.5 m length, temperature measurements were recorded with 5.7 mm and 3.8 mm vertical spacing, respectively. The HR-DTS systems were installed 0.7 m deep in the streambed sediments, crossing both the sediment-water and the water-air interface, thus yielding high resolution water and air temperature data as well. One of the HR-DTS systems was installed in the open stream channel with only topographical shading, while the other HR-DTS system was placed 7 m upstream, under the canopy of a tree, thus representing the shaded conditions with reduced influence of solar radiation. Temperature measurements were taken with 30 min intervals between 16 April and 25 June 2013. The thermal conductivity of streambed sediments was calibrated in a 1D flow

  15. Acclimation responses to temperature vary with vertical stratification: implications for vulnerability of soil-dwelling species to extreme temperature events. (United States)

    van Dooremalen, Coby; Berg, Matty P; Ellers, Jacintha


    The occurrence of summer heat waves is predicted to increase in amplitude and frequency in the near future, but the consequences of such extreme events are largely unknown, especially for belowground organisms. Soil organisms usually exhibit strong vertical stratification, resulting in more frequent exposure to extreme temperatures for surface-dwelling species than for soil-dwelling species. Therefore soil-dwelling species are expected to have poor acclimation responses to cope with temperature changes. We used five species of surface-dwelling and four species of soil-dwelling Collembola that habituate different depths in the soil. We tested for differences in tolerance to extreme temperatures after acclimation to warm and cold conditions. We also tested for differences in acclimation of the underlying physiology by looking at changes in membrane lipid composition. Chill coma recovery time, heat knockdown time and fatty acid profiles were determined after 1 week of acclimation to either 5 or 20 °C. Our results showed that surface-dwelling Collembola better maintained increased heat tolerance across acclimation temperatures, but no such response was found for cold tolerance. Concordantly, four of the five surface-dwelling Collembola showed up to fourfold changes in relative abundance of fatty acids after 1 week of acclimation, whereas none of the soil-dwelling species showed a significant adjustment in fatty acid composition. Strong physiological responses to temperature fluctuations may have become redundant in soil-dwelling species due to the relative thermal stability of their subterranean habitat. Based on the results of the four species studied, we expect that unless soil-dwelling species can temporarily retreat to avoid extreme temperatures, the predicted increase in heat waves under climatic change renders these soil-dwelling species more vulnerable to extinction than species with better physiological capabilities. Being able to act under a larger thermal

  16. Nonlinear response of tropical lower-stratospheric temperature and water vapor to ENSO

    Directory of Open Access Journals (Sweden)

    C. I. Garfinkel


    Full Text Available A series of simulations using the NASA Goddard Earth Observing System Chemistry–Climate Model are analyzed in order to aid in the interpretation of observed interannual and sub-decadal variability in the tropical lower stratosphere over the past 35 years. The impact of El Niño–Southern Oscillation on temperature and water vapor in this region is nonlinear in boreal spring. While moderate El Niño events lead to cooling in this region, strong El Niño events lead to warming, even as the response of the large-scale Brewer–Dobson circulation appears to scale nearly linearly with El Niño. This nonlinearity is shown to arise from the response in the Indo-West Pacific to El Niño: strong El Niño events lead to tropospheric warming extending into the tropical tropopause layer and up to the cold point in this region, where it allows for more water vapor to enter the stratosphere. The net effect is that both strong La Niña and strong El Niño events lead to enhanced entry water vapor and stratospheric moistening in boreal spring and early summer. These results lead to the following interpretation of the contribution of sea surface temperatures to the decline in water vapor in the early 2000s: the very strong El Niño event in 1997/1998, followed by more than 2 consecutive years of La Niña, led to enhanced lower-stratospheric water vapor. As this period ended in early 2001, entry water vapor concentrations declined. This effect accounts for approximately one-quarter of the observed drop.

  17. Nonlinear response of tropical lower-stratospheric temperature and water vapor to ENSO (United States)

    Garfinkel, Chaim I.; Gordon, Amit; Oman, Luke D.; Li, Feng; Davis, Sean; Pawson, Steven


    A series of simulations using the NASA Goddard Earth Observing System Chemistry-Climate Model are analyzed in order to aid in the interpretation of observed interannual and sub-decadal variability in the tropical lower stratosphere over the past 35 years. The impact of El Niño-Southern Oscillation on temperature and water vapor in this region is nonlinear in boreal spring. While moderate El Niño events lead to cooling in this region, strong El Niño events lead to warming, even as the response of the large-scale Brewer-Dobson circulation appears to scale nearly linearly with El Niño. This nonlinearity is shown to arise from the response in the Indo-West Pacific to El Niño: strong El Niño events lead to tropospheric warming extending into the tropical tropopause layer and up to the cold point in this region, where it allows for more water vapor to enter the stratosphere. The net effect is that both strong La Niña and strong El Niño events lead to enhanced entry water vapor and stratospheric moistening in boreal spring and early summer. These results lead to the following interpretation of the contribution of sea surface temperatures to the decline in water vapor in the early 2000s: the very strong El Niño event in 1997/1998, followed by more than 2 consecutive years of La Niña, led to enhanced lower-stratospheric water vapor. As this period ended in early 2001, entry water vapor concentrations declined. This effect accounts for approximately one-quarter of the observed drop.

  18. A sandwich-designed temperature-gradient incubator for studies of microbial temperature responses

    DEFF Research Database (Denmark)

    Elsgaard, Lars; Jørgensen, L.W.


    of 28-ml test tubes. An electric plate heats one end of the TGI end and the other end is cooled by thermoelectric Peltier elements in combination with a liquid cooling system. The TGI is equipped with 24 calibrated Pt-100 temperature sensors and insulated by polyurethane plates. A PC-operated SCADA...

  19. Roots affect the response of heterotrophic soil respiration to temperature in tussock grass microcosms. (United States)

    Graham, Scott L; Millard, Peter; Hunt, John E; Rogers, Graeme N D; Whitehead, David


    While the temperature response of soil respiration (R(S)) has been well studied, the partitioning of heterotrophic respiration (R(H)) by soil microbes from autotrophic respiration (R(A)) by roots, known to have distinct temperature sensitivities, has been problematic. Further complexity stems from the presence of roots affecting R(H), the rhizosphere priming effect. In this study the short-term temperature responses of R(A) and R(H) in relation to rhizosphere priming are investigated. Temperature responses of R(A), R(H) and rhizosphere priming were assessed in microcosms of Poa cita using a natural abundance δ(13)C discrimination approach. The temperature response of R(S) was found to be regulated primarily by R(A), which accounted for 70 % of total soil respiration. Heterotrophic respiration was less sensitive to temperature in the presence of plant roots, resulting in negative priming effects with increasing temperature. The results emphasize the importance of roots in regulating the temperature response of R(S), and a framework is presented for further investigation into temperature effects on heterotrophic respiration and rhizosphere priming, which could be applied to other soil and vegetation types to improve models of soil carbon turnover.

  20. Mechanical properties and fracture behaviour of ODS steel friction stir welds at variable temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, H., E-mail: [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Serrano, M.; Hernandez, R. [Structural Materials Division, Technology Department, CIEMAT, Avda de la Complutense 40, 28040 Madrid (Spain); Cater, S. [Friction and Forge Processes Department, Joining Technologies Group, TWI Technology Centre (Yorkshire), Advanced Manufacturing Park, Wallis Way, Catcliffe, Rotherham S60 5TZ (United Kingdom); Jimenez-Melero, E. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom)


    We have assessed the microstructure and the temperature-dependent mechanical behaviour of five bead-on-plate friction stir welds of Oxide Dispersion Strengthened (ODS) steel, produced using systematic changes to the tool rotation and traverse speed. Friction stir welding can potentially retain the fine dispersion of nanoparticles, and therefore also the high-temperature strength and radiation damage resistance of these materials. Tensile testing was carried out on the MA956 base material at a range of temperatures, from room temperature up to 750 °C. The mechanical properties of the welds were investigated via tensile testing at room temperature and at 500 °C, together with micro-hardness testing. The welds exhibited similar strength and ductility to the base material at both testing temperatures as welding caused a partial loss of particle strengthening, alongside an increase in grain boundary strengthening due to a greatly refined grain size in the stir zones. The micro-hardness data revealed a trend of increasing hardness with increasing tool traverse speed or decreasing rotation speed. This was attributed to the smaller grain size and lower nanoparticle number density in the welds created with these parameters. At 500 °C, the yield stress and ultimate tensile stress of the base material and the welds decreased, due to a progressive reduction in both the Orowan-type particle strengthening and the grain boundary strengthening.

  1. Laminar free convection with variable fluid properties in vertical ducts having uniform wall temperature

    International Nuclear Information System (INIS)

    Aihara, Toshio; Maruyama, Shigenao; Choi, Jun-Seop.


    Recently, the research on free convection in vertical ducts has become active again concerning the problem of cooling in nuclear reactor accidents and the cooling of electronic equipment. Generally, in the convection heat transfer in ducts, when the wall temperature is high, the fluid temperature in the ducts conspicuously changes, accordingly, the temperature dependence of the properties cannot be neglected. In this study, about the laminar free convection in parallel plates and a circular pipe having uniform wall temperature, the numerical analysis taking the temperature dependence of all properties into account was carried out, thus the effect of the temperature dependence of properties exerted on free convection heat transfer was clarified, and the relation to the solution in constant properties was examined. Moreover, by introducing a new representative dimension, it was attempted to express mean heat transfer coefficient which is independent of the form of ducts in unified way. The mean Nusselt number of the constant property solution using entrance pressure condition agreed very well with the exact numerical solution. (Kako, I.)

  2. Sensitivity of extreme precipitation to temperature: the variability of scaling factors from a regional to local perspective (United States)

    Schroeer, K.; Kirchengast, G.


    Potential increases in extreme rainfall induced hazards in a warming climate have motivated studies to link precipitation intensities to temperature. Increases exceeding the Clausius-Clapeyron (CC) rate of 6-7%/°C-1 are seen in short-duration, convective, high-percentile rainfall at mid latitudes, but the rates of change cease or revert at regionally variable threshold temperatures due to moisture limitations. It is unclear, however, what these findings mean in term of the actual risk of extreme precipitation on a regional to local scale. When conditioning precipitation intensities on local temperatures, key influences on the scaling relationship such as from the annual cycle and regional weather patterns need better understanding. Here we analyze these influences, using sub-hourly to daily precipitation data from a dense network of 189 stations in south-eastern Austria. We find that the temperature sensitivities in the mountainous western region are lower than in the eastern lowlands. This is due to the different weather patterns that cause extreme precipitation in these regions. Sub-hourly and hourly intensities intensify at super-CC and CC-rates, respectively, up to temperatures of about 17 °C. However, we also find that, because of the regional and seasonal variability of the precipitation intensities, a smaller scaling factor can imply a larger absolute change in intensity. Our insights underline that temperature precipitation scaling requires careful interpretation of the intent and setting of the study. When this is considered, conditional scaling factors can help to better understand which influences control the intensification of rainfall with temperature on a regional scale.

  3. Large Scale Variability of Phytoplankton Blooms in the Arctic and Peripheral Seas: Relationships with Sea Ice, Temperature, Clouds, and Wind (United States)

    Comiso, Josefino C.; Cota, Glenn F.


    Spatially detailed satellite data of mean color, sea ice concentration, surface temperature, clouds, and wind have been analyzed to quantify and study the large scale regional and temporal variability of phytoplankton blooms in the Arctic and peripheral seas from 1998 to 2002. In the Arctic basin, phytoplankton chlorophyll displays a large symmetry with the Eastern Arctic having about fivefold higher concentrations than those of the Western Arctic. Large monthly and yearly variability is also observed in the peripheral seas with the largest blooms occurring in the Bering Sea, Sea of Okhotsk, and the Barents Sea during spring. There is large interannual and seasonal variability in biomass with average chlorophyll concentrations in 2002 and 2001 being higher than earlier years in spring and summer. The seasonality in the latitudinal distribution of blooms is also very different such that the North Atlantic is usually most expansive in spring while the North Pacific is more extensive in autumn. Environmental factors that influence phytoplankton growth were examined, and results show relatively high negative correlation with sea ice retreat and strong positive correlation with temperature in early spring. Plankton growth, as indicated by biomass accumulation, in the Arctic and subarctic increases up to a threshold surface temperature of about 276-277 degree K (3-4 degree C) beyond which the concentrations start to decrease suggesting an optimal temperature or nutrient depletion. The correlation with clouds is significant in some areas but negligible in other areas, while the correlations with wind speed and its components are generally weak. The effects of clouds and winds are less predictable with weekly climatologies because of unknown effects of averaging variable and intermittent physical forcing (e.g. over storm event scales with mixing and upwelling of nutrients) and the time scales of acclimation by the phytoplankton.

  4. Extended exposure to elevated temperature affects escape response behaviour in coral reef fishes

    Directory of Open Access Journals (Sweden)

    Donald T. Warren


    Full Text Available The threat of predation, and the prey’s response, are important drivers of community dynamics. Yet environmental temperature can have a significant effect on predation avoidance techniques such as fast-start performance observed in marine fishes. While it is known that temperature increases can influence performance and behaviour in the short-term, little is known about how species respond to extended exposure during development. We produced a startle response in two species of damselfish, the lemon damsel Pomacentrus moluccensis, and the Ambon damselfish Pomacentrus amboinensis, by the repeated use of a drop stimulus. We show that the length of thermal exposure of juveniles to elevated temperature significantly affects this escape responses. Short-term (4d exposure to warmer temperature affected directionality and responsiveness for both species. After long-term (90d exposure, only P. moluccensis showed beneficial plasticity, with directionality returning to control levels. Responsiveness also decreased in both species, possibly to compensate for higher temperatures. There was no effect of temperature or length of exposure on latency to react, maximum swimming speed, or escape distance suggesting that the physical ability to escape was maintained. Evidence suggests that elevated temperature may impact some fish species through its effect on the behavioural responses while under threat rather than having a direct influence on their physical ability to perform an effective escape response.

  5. Development of an experimental variable temperature set-up for a temperature range from 2.2 K to 325 K for cost-effective temperature sensor calibration (United States)

    Pal, Sandip; Kar, Ranjan; Mandal, Anupam; Das, Ananda; Saha, Subrata


    A prototype of a variable temperature insert has been developed in-house as a cryogenic thermometer calibration facility. It was commissioned in fulfilment of the very stringent requirements of the temperature control of the cryogenic system. The calibration facility is designed for calibrating industrial cryogenic thermometers that include a temperature sensor and the wires heat-intercept in the 2.2 K-325 K temperature range. The isothermal section of the calibration block onto which the thermometers are mounted is weakly linked with the temperature control zone mounted with cooling capillary coil and cryogenic heater. The connecting wires of the thermometer are thermally anchored with the support of the temperature insert. The calibration procedure begins once the temperature of the support is stabilized. Homogeneity of the calibration block’s temperature is established both by simulation and by cross-comparison of two calibrated sensors. The absolute uncertainty present in temperature measurement is calculated and found comparable with the measured uncertainty at different temperature points. Measured data is presented in comparison to the standard thermometers at fixed points and it is possible to infer that the absolute accuracy achieved is better than  ±0.5% of the reading in comparison to the fixed point temperature. The design and development of simpler, low cost equipment, and approach to analysis of the calibration results are discussed further in this paper, so that it can be easily devised by other researchers.

  6. A Water Temperature Simulation Model for Rice Paddies With Variable Water Depths (United States)

    Maruyama, Atsushi; Nemoto, Manabu; Hamasaki, Takahiro; Ishida, Sachinobu; Kuwagata, Tsuneo


    A water temperature simulation model was developed to estimate the effects of water management on the thermal environment in rice paddies. The model was based on two energy balance equations: for the ground and for the vegetation, and considere