Science.gov

Sample records for short-term climate variability

  1. EVALUATING SHORT-TERM CLIMATE VARIABILITY IN THE LATE HOLOCENE OF THE NORTHERN GREAT PLAINS

    SciTech Connect

    Joseph H. Hartman

    1999-09-01

    This literature study investigated methods and areas to deduce climate change and climate patterns, looking for short-term cycle phenomena and the means to interpret them. Many groups are actively engaged in intensive climate-related research. Ongoing research might be (overly) simplified into three categories: (1) historic data on weather that can be used for trend analysis and modeling; (2) detailed geological, biological (subfossil), and analytical (geochemical, radiocarbon, etc.) studies covering the last 10,000 years (about since last glaciation); and (3) geological, paleontological, and analytical (geochemical, radiometric, etc.) studies over millions of years. Of importance is our ultimate ability to join these various lines of inquiry into an effective means of interpretation. At this point, the process of integration is fraught with methodological troubles and misconceptions about what each group can contribute. This project has met its goals to the extent that it provided an opportunity to study resource materials and consider options for future effort toward the goal of understanding the natural climate variation that has shaped our current civilization. A further outcome of this project is a proposed methodology based on ''climate sections'' that provides spatial and temporal correlation within a region. The method would integrate cultural and climate data to establish the climate history of a region with increasing accuracy with progressive study and scientific advancement (e. g., better integration of regional and global models). The goal of this project is to better understand natural climatic variations in the recent past (last 5000 years). The information generated by this work is intended to provide better context within which to examine global climate change. The ongoing project will help to establish a basis upon which to interpret late Holocene short-term climate variability as evidenced in various studies in the northern Great Plains, northern

  2. Application of Remote Sensing to Assess the Impact of Short Term Climate Variability on Coastal Sedimentation

    NASA Technical Reports Server (NTRS)

    Menzel, W. Paul; Huh, Oscar K.; Walker, Nan

    2004-01-01

    The purpose of this joint University of Wisconsin (UW) and Louisiana State University (LSU) project has been to relate short term climate variation to response in the coastal zone of Louisiana in an attempt to better understand how the coastal zone is shaped by climate variation. Climate variation in this case largely refers to variation in surface wind conditions that affect wave action and water currents in the coastal zone. The primary region of focus was the Atchafalaya Bay and surrounding bays in the central coastal region of Louisiana. Suspended solids in the water column show response to wind systems both in quantity (through resuspension) and in the pattern of dispersement or transport. Wind systems associated with cold fronts are influenced by short term climate variation. Wind energy was used as the primary signature of climate variation in this study because winds are a significant influence on sediment transport in the micro-tidal Gilf of Mexico coastal zone. Using case studies, the project has been able to investigate the influence of short term climate variation on sediment transport. Wind energy data, collected daily for National Weather Service (NWS) stations at Lake Charles and New Orleans, LA, were used as an indicator of short term climate variation influence on seasonal time scales. A goal was to relate wind energy to coastal impact through sediment transport. This goal was partially accomplished by combining remote sensing and wind energy data. Daily high resolution remote sensing observations are needed to monitor the complex coastal zone environment, where winds, tides, and water level all interact to influence sediment transport. The NASA Earth Observing System (EOS) era brings hope for documenting and revealing response of the complex coastal transport mosaic through regular high spatial resolution observations from the Moderate resolution Imaging Spectrometer (MODIS) instrument. MODIS observations were sampled in this project for

  3. Application of Remote Sensing to Assess the Impact of Short Term Climate Variability on Coastal Sedimentation

    NASA Technical Reports Server (NTRS)

    Moeller, Christopher C.; Gunshor, Mathew M.; Menzel, W. Paul; Huh, Oscar K.; Walker, Nan D.; Rouse, Lawrence J.; Frey, Herbert V. (Technical Monitor)

    2001-01-01

    The University of Wisconsin and Louisiana State University have teamed to study the forcing of winter season cold frontal wind systems on sediment distribution patterns and geomorphology in the Louisiana coastal zone. Wind systems associated with cold fronts have been shown to modify coastal circulation and resuspend sediments along the microtidal Louisiana coast. The assessment includes quantifying the influence of cumulative winter season atmospheric forcing (through surface wind observations) from year to year in response to short term climate variability, such as El Nino events. A correlation between winter cyclone frequency and the strength of El Nino events has been suggested. The atmospheric forcing data are being correlated to geomorphic measurements along western Louisiana's prograding muddy coast. Remote sensing data is being used to map and track sediment distribution patterns for various wind conditions. Transferring a suspended sediment concentration (SSC) algorithm to EOS MODIS observations will enable estimates of SSC in case 2 waters over the global domain. Progress in Year 1 of this study has included data collection and analysis of wind observations for atmospheric forcing characterization, a field activity (TX-2001) to collect in situ water samples with co-incident remote sensing measurements from the NASA ER-2 based MODIS Airborne Simulator (MAS) and the EOS Terra based MODerate resolution Imaging Spectroradiometer (MODIS) instruments, aerial photography and of sediment burial pipe field measurements along the prograding muddy Chenier Plain coast of western Louisiana for documenting coastal change in that dynamic region, and routine collection of MODIS 250 in resolution data for monitoring coastal sediment patterns. The data sets are being used in a process to transfer an SSC estimation algorithm to the MODIS platform. Work is underway on assessing coastal transport for the winter 2000-01 season. Water level data for use in a Geomorphic Impact

  4. Short-term Holocene climate variability in coastal mid-Norway - the terrestrial response to the North Atlantic climate

    NASA Astrophysics Data System (ADS)

    Klug, M.; Seidenkrantz, M.-S.; Piotrowski, J. A.; Heinemeier, J.; Rubensdotter, L.; Faust, J.; Knies, J.

    2012-04-01

    Coastal areas are known to be susceptible to maritime climate variations, especially where prevailing wind directions provide humidity and latent heat to the land masses. Temperature reconstructions from the eastern North Atlantic, and from northern and western Norway show simultaneous changes on millennial to centennial scales during the Holocene. However also latitudinal climatic differences occur during the Holocene. These indicate a more complex system along the Norwegian coast with regional temperature variations depending on more than only North Atlantic's climate. Climate sensitive archives such as lake sediments in coastal mid-Norway provide the opportunity to study the influence of and the terrestrial response to climate variations mediated by the North Atlantic and allow the extension of our knowledge about regional peculiarities along the Norwegian coast. Lake Blomstertjønna, a small lake outside Trondheim at 427 m a.s.l., enables a detailed study of climatic and environmental variations during the Holocene. The entire succession is 590 cm long and is composed of minerogenic sediments at the bottom and dominating biogenic sediments in the upper 495 cm. Radiocarbon dating of macrofossils aided by tephra identification reveal a lake history that started after deglaciation at about 12 kyr BP and shifted to a biogenic productive lake with overall uniform sedimentation rates at about 11 kyr BP. Biogeochemical proxies like total organic carbon and total sulphur and geophysical parameters show a weak, i.e. more even response to climatic variations in the gyttja-rich section and indicate that temperature was not a limiting factor for the lake productivity. In contrast, geochemical elemental ratios from XRF scanning reveal a pronounced long- and short-term variability of elemental composition. The long-term trend of selected elemental ratios reflects the general Holocene temperature evolution with higher values during the Holocene Thermal Maximum and a

  5. Recurring flood distribution patterns related to short-term Holocene climatic variability.

    PubMed

    Benito, Gerardo; Macklin, Mark G; Panin, Andrei; Rossato, Sandro; Fontana, Alessandro; Jones, Anna F; Machado, Maria J; Matlakhova, Ekaterina; Mozzi, Paolo; Zielhofer, Christoph

    2015-01-01

    Millennial- and multi-centennial scale climate variability during the Holocene has been well documented, but its impact on the distribution and timing of extreme river floods has yet to be established. Here we present a meta-analysis of more than 2000 radiometrically dated flood units to reconstruct centennial-scale Holocene flood episodes in Europe and North Africa. Our data analysis shows a general increase in flood frequency after 5000 cal. yr BP consistent with a weakening in zonal circulation over the second half of the Holocene, and with an increase in winter insolation. Multi-centennial length phases of flooding in UK and central Europe correspond with periods of minimum solar irradiance, with a clear trend of increasing flood frequency over the last 1000 years. Western Mediterranean regions show synchrony of flood episodes associated with negative phases of the North Atlantic Oscillation that are out-of-phase with those evident within the eastern Mediterranean. This long-term flood record reveals complex but geographically highly interconnected climate-flood relationships, and provides a new framework to understand likely future spatial changes of flood frequency. PMID:26549043

  6. Recurring flood distribution patterns related to short-term Holocene climatic variability

    PubMed Central

    Benito, Gerardo; Macklin, Mark G.; Panin, Andrei; Rossato, Sandro; Fontana, Alessandro; Jones, Anna F.; Machado, Maria J.; Matlakhova, Ekaterina; Mozzi, Paolo; Zielhofer, Christoph

    2015-01-01

    Millennial- and multi-centennial scale climate variability during the Holocene has been well documented, but its impact on the distribution and timing of extreme river floods has yet to be established. Here we present a meta-analysis of more than 2000 radiometrically dated flood units to reconstruct centennial-scale Holocene flood episodes in Europe and North Africa. Our data analysis shows a general increase in flood frequency after 5000 cal. yr BP consistent with a weakening in zonal circulation over the second half of the Holocene, and with an increase in winter insolation. Multi-centennial length phases of flooding in UK and central Europe correspond with periods of minimum solar irradiance, with a clear trend of increasing flood frequency over the last 1000 years. Western Mediterranean regions show synchrony of flood episodes associated with negative phases of the North Atlantic Oscillation that are out-of-phase with those evident within the eastern Mediterranean. This long-term flood record reveals complex but geographically highly interconnected climate-flood relationships, and provides a new framework to understand likely future spatial changes of flood frequency. PMID:26549043

  7. Recurring flood distribution patterns related to short-term Holocene climatic variability

    NASA Astrophysics Data System (ADS)

    Benito, Gerardo; Macklin, Mark G.; Panin, Andrei; Rossato, Sandro; Fontana, Alessandro; Jones, Anna F.; Machado, Maria J.; Matlakhova, Ekaterina; Mozzi, Paolo; Zielhofer, Christoph

    2015-11-01

    Millennial- and multi-centennial scale climate variability during the Holocene has been well documented, but its impact on the distribution and timing of extreme river floods has yet to be established. Here we present a meta-analysis of more than 2000 radiometrically dated flood units to reconstruct centennial-scale Holocene flood episodes in Europe and North Africa. Our data analysis shows a general increase in flood frequency after 5000 cal. yr BP consistent with a weakening in zonal circulation over the second half of the Holocene, and with an increase in winter insolation. Multi-centennial length phases of flooding in UK and central Europe correspond with periods of minimum solar irradiance, with a clear trend of increasing flood frequency over the last 1000 years. Western Mediterranean regions show synchrony of flood episodes associated with negative phases of the North Atlantic Oscillation that are out-of-phase with those evident within the eastern Mediterranean. This long-term flood record reveals complex but geographically highly interconnected climate-flood relationships, and provides a new framework to understand likely future spatial changes of flood frequency.

  8. Sensitivity of tropical stratospheric and mesospheric ozone to short-term solar variability: observations vs chemistry climate model simulations

    NASA Astrophysics Data System (ADS)

    bossay, sébastien; marchand, marion; bekki, slimane; thuillier, gérard; hauchecorne, alain; lefèvre, franck; Onishi, tatsuo

    2014-05-01

    The response of stratospheric and mesospheric ozone in the tropics to short-term solar ultraviolet variations (i.e. 27-day solar rotational cycle) over the descending phases of two consecutive solar cycles (solar cycles 22 and 23) is investigated using daily ozone measurements (MLS on UARS and AURA, GOMOS on ENVISAT), reconstructed solar spectra variations and stratospheric chemistry-climate model calculations. Daily solar spectra are taken from the NRL-SSI solar reconstruction model. The chemistry-climate model is forced at the top by the reconstructed solar spectra, and at the surface by analyzed sea-surface temperatures and sea-ice. The solar variable for regression analysis is the UV flux at 205nm, within an atmospheric window region that is crucial for the ozone photochemistry. The same spectral analysis (cross-correlation, wavelet and fourier transform, coherence,…) is carried out on all the observations and model simulations, and for both periods. In the stratosphere, statistically significant correlation is found between around 1 and 10 hPa with a peak at about 4 hPa (~36 km) for both periods. However the ozone sensitivity to solar variations (defined as the percentage change in ozone for 1% change in solar 205nm flux) is two times weaker during the solar cycle 23 (0.2) than during the solar cycle 22 (0.4%/%). Moreover, wavelet transforms show that the magnitude and occurrence of the solar signal in ozone data is highly variable temporally and vanishes during several solar rotations. This intermittence is much more pronounced during the solar cycle 23 than during the solar cycle 22. The chemistry-climate model calculations are able to reproduce most of the features of the solar signal in tropical stratospheric ozone including the differences between the solar cycle 22 and 23. In the mesosphere, the analysis of the GOMOS data reveals a clear 27-day solar signal in ozone. The results have implications for the impact of solar variability on ozone and

  9. Short Term Exogenic Climate Change Forcing

    NASA Astrophysics Data System (ADS)

    Krahenbuhl, Daniel

    Several short term exogenic forcings affecting Earth's climate are but recently identified. Lunar nutation periodicity has implications for numerical meteorological prediction. Abrupt shifts in solar wind bulk velocity, particle density, and polarity exhibit correlation with terrestrial hemispheric vorticity changes, cyclonic strengthening and the intensification of baroclinic disturbances. Galactic Cosmic ray induced tropospheric ionization modifies cloud microphysics, and modulates the global electric circuit. This dissertation is constructed around three research questions: (1): What are the biweekly declination effects of lunar gravitation upon the troposphere? (2): How do United States severe weather reports correlate with heliospheric current sheet crossings? and (3): How does cloud cover spatially and temporally vary with galactic cosmic rays? Study 1 findings show spatial consistency concerning lunar declination extremes upon Rossby longwaves. Due to the influence of Rossby longwaves on synoptic scale circulation, our results could theoretically extend numerical meteorological forecasting. Study 2 results indicate a preference for violent tornadoes to occur prior to a HCS crossing. Violent tornadoes (EF3+) are 10% more probable to occur near, and 4% less probable immediately after a HCS crossing. The distribution of hail and damaging wind reports do not mirror this pattern. Polarity is critical for the effect. Study 3 results confirm anticorrelation between solar flux and low-level marine-layer cloud cover, but indicate substantial regional variability between cloud cover altitude and GCRs. Ultimately, this dissertation serves to extend short term meteorological forecasting, enhance climatological modeling and through analysis of severe violent weather and heliospheric events, protect property and save lives.

  10. Major modes of short-term climate variability in the newly developed NUIST Earth System Model (NESM)

    NASA Astrophysics Data System (ADS)

    Cao, Jian; Wang, Bin; Xiang, Baoqiang; Li, Juan; Wu, Tianjie; Fu, Xiouhua; Wu, Liguang; Min, Jinzhong

    2015-05-01

    A coupled earth system model (ESM) has been developed at the Nanjing University of Information Science and Technology (NUIST) by using version 5.3 of the European Centre Hamburg Model (ECHAM), version 3.4 of the Nucleus for European Modelling of the Ocean (NEMO), and version 4.1 of the Los Alamos sea ice model (CICE). The model is referred to as NUIST ESM1 (NESM1). Comprehensive and quantitative metrics are used to assess the model's major modes of climate variability most relevant to subseasonal-to-interannual climate prediction. The model's assessment is placed in a multi-model framework. The model yields a realistic annual mean and annual cycle of equatorial SST, and a reasonably realistic precipitation climatology, but has difficulty in capturing the spring-fall asymmetry and monsoon precipitation domains. The ENSO mode is reproduced well with respect to its spatial structure, power spectrum, phase locking to the annual cycle, and spatial structures of the central Pacific (CP)-ENSO and eastern Pacific (EP)-ENSO; however, the equatorial SST variability, biennial component of ENSO, and the amplitude of CP-ENSO are overestimated. The model captures realistic intraseasonal variability patterns, the vertical-zonal structures of the first two leading predictable modes of Madden-Julian Oscillation (MJO), and its eastward propagation; but the simulated MJO speed is significantly slower than observed. Compared with the T42 version, the high resolution version (T159) demonstrates improved simulation with respect to the climatology, interannual variance, monsoon-ENSO lead-lag correlation, spatial structures of the leading mode of the Asian-Australian monsoon rainfall variability, and the eastward propagation of the MJO.

  11. Tree ring isotopes of beech and spruce in response to short-term climate variability across Central European sites: Common and contrasting physiological mechanisms

    NASA Astrophysics Data System (ADS)

    Weigt, Rosemarie; Klesse, Stefan; Treydte, Kerstin; Frank, David; Saurer, Matthias; Siegwolf, Rolf T. W.

    2016-04-01

    The combined study of tree-ring width and stable C and O isotopes provides insight in the coherences between carbon allocation during stem growth and the preceding conditions of gas exchange and formation of photosynthates as all influenced by environmental variation. In this large-scale study comprising 10 sites across a range of climate gradients (temperature, precipitation) throughout Central Europe, we investigated tree-rings in European beech (Fagus sylvatica) and Norway spruce (Picea abies) trees. The sampling design included larger and smaller trees. The short-term, i.e. year-to-year, variability in the isotope time series over 100 yrs was analyzed in relation to tree-ring growth and climate variation. The generally strong correlation between the year-to-year differences in δ13C (corrected for the atmospheric shift due to 13C-depleted CO2 from fossil combustion) and δ18O across most sites emphasized the role of stomatal conductance in controlling leaf gas exchange. However, the correlation between both isotopes decreased during some periods. At several sites this reduction in correlation was particularly pronounced during recent decades. This suggests a decoupling between stomatal and photosynthetic responses to environmental conditions on the one hand, and carbon allocation to stem tissue on the other hand. Variability in the isotopic ratio largely responded to summer climate, but was weakly correlated to annual stem growth. In contrast, climate sensitivity of radial growth in both species was rather site-dependent, and was strongest at the driest (in terms of soil water capacity) site. We will also present results of isotope responses with respect to extreme climate events. Understanding the underlying physiological mechanisms controlling the short-term variation in tree-ring signals will help to assess and more precisely constrain the possible range of growth performance of these ecologically and economically important tree species under future climate

  12. Impacts of long- and short-term climate variability on terrestrial biogenic emissions and their influence on the remote tropical troposphere

    NASA Astrophysics Data System (ADS)

    Monks, S. A.; Arnold, S.; Guenther, A. B.; Emmons, L. K.; Carpenter, L.; Read, K.

    2013-12-01

    Terrestrial vegetation emits a wide range of biogenic volatile organic compounds (BVOC) into the atmosphere (~1150 TgC/yr), which accounts for ~90% of total VOC surface emissions. Emissions of BVOC are largely dependent on environmental factors such as sunlight and temperature, which makes them sensitive to both long-term and short-term changes in the climate system. ENSO is well-known to have global impacts on temperature and precipitation, and therefore has the potential to impact regional BVOC emissions on inter-annual time-scales. In addition to this, increased global mean temperatures and atmospheric carbon dioxide (CO2) concentrations over the past few decades may also have affected BVOC emissions. Once in the atmosphere, these compounds have the ability to influence global and regional atmospheric chemistry and climate through impacts on the hydroxyl radical, ozone, particulate matter and methane lifetime. We use the NCAR Community Land Model (CLM) coupled to the Model of Emissions of Gases and Aerosols from Nature (MEGANv2) to investigate both long-term changes and inter-annual variability of BVOC emissions over a 50-year period at regional and global spatial-scales. This is done by considering the impacts of increasing temperatures and CO2 concentrations on long-term emissions of BVOC separately, in addition to using the Multivariate ENSO Index (MEI) to investigate the regional response in emissions due to natural ENSO variability. Global composites of ENSO-positive and ENSO-negative phase emissions are then used to drive global atmospheric chemistry simulations using the NCAR Community Earth System Model (CESM). Through comparisons with 6 years of measurements from the Cape Verde observatory in the tropical Atlantic Ocean, we explore the role of inter-annual variability in terrestrial biogenic emissions in controlling the observed variability in methanol, acetone and acetaldehyde in the remote tropical atmosphere. By accounting for inter-annual changes in

  13. Short-Term Effects of Climatic Variables on Hand, Foot, and Mouth Disease in Mainland China, 2008–2013: A Multilevel Spatial Poisson Regression Model Accounting for Overdispersion

    PubMed Central

    Yang, Fang; Yang, Min; Hu, Yuehua; Zhang, Juying

    2016-01-01

    Background Hand, Foot, and Mouth Disease (HFMD) is a worldwide infectious disease. In China, many provinces have reported HFMD cases, especially the south and southwest provinces. Many studies have found a strong association between the incidence of HFMD and climatic factors such as temperature, rainfall, and relative humidity. However, few studies have analyzed cluster effects between various geographical units. Methods The nonlinear relationships and lag effects between weekly HFMD cases and climatic variables were estimated for the period of 2008–2013 using a polynomial distributed lag model. The extra-Poisson multilevel spatial polynomial model was used to model the exact relationship between weekly HFMD incidence and climatic variables after considering cluster effects, provincial correlated structure of HFMD incidence and overdispersion. The smoothing spline methods were used to detect threshold effects between climatic factors and HFMD incidence. Results The HFMD incidence spatial heterogeneity distributed among provinces, and the scale measurement of overdispersion was 548.077. After controlling for long-term trends, spatial heterogeneity and overdispersion, temperature was highly associated with HFMD incidence. Weekly average temperature and weekly temperature difference approximate inverse “V” shape and “V” shape relationships associated with HFMD incidence. The lag effects for weekly average temperature and weekly temperature difference were 3 weeks and 2 weeks. High spatial correlated HFMD incidence were detected in northern, central and southern province. Temperature can be used to explain most of variation of HFMD incidence in southern and northeastern provinces. After adjustment for temperature, eastern and Northern provinces still had high variation HFMD incidence. Conclusion We found a relatively strong association between weekly HFMD incidence and weekly average temperature. The association between the HFMD incidence and climatic

  14. Local short-term variability in solar irradiance

    NASA Astrophysics Data System (ADS)

    Lohmann, Gerald M.; Monahan, Adam H.; Heinemann, Detlev

    2016-05-01

    Characterizing spatiotemporal irradiance variability is important for the successful grid integration of increasing numbers of photovoltaic (PV) power systems. Using 1 Hz data recorded by as many as 99 pyranometers during the HD(CP)2 Observational Prototype Experiment (HOPE), we analyze field variability of clear-sky index k* (i.e., irradiance normalized to clear-sky conditions) and sub-minute k* increments (i.e., changes over specified intervals of time) for distances between tens of meters and about 10 km. By means of a simple classification scheme based on k* statistics, we identify overcast, clear, and mixed sky conditions, and demonstrate that the last of these is the most potentially problematic in terms of short-term PV power fluctuations. Under mixed conditions, the probability of relatively strong k* increments of ±0.5 is approximately twice as high compared to increment statistics computed without conditioning by sky type. Additionally, spatial autocorrelation structures of k* increment fields differ considerably between sky types. While the profiles for overcast and clear skies mostly resemble the predictions of a simple model published by , this is not the case for mixed conditions. As a proxy for the smoothing effects of distributed PV, we finally show that spatial averaging mitigates variability in k* less effectively than variability in k* increments, for a spatial sensor density of 2 km-2.

  15. Finding Short-Term Variability in Methanol Masers

    NASA Astrophysics Data System (ADS)

    Bonin, Samuel; Barott, W. C.; Catanach, T.

    2012-05-01

    The Allen Telescope Array (ATA) performed 53 observations of 6.7 GHz methanol masers between July 2010 and January 2011 in an effort to identify short-timescale variability. With the notable exception of Weisberg et al. (2005), few analyses have been performed analyzing variability in masers on timescales of minutes or less. This work is aimed both at providing additional data (including refined positions) on the catalog of observed sources as well as identifying the prevalence and cause of short-term phenomena. Observations utilized both the ATA correlator (for mapping) and beamformer (for recording voltage time series). A combination of Fast-Fourier Transforms and Continuous Wavelet Transforms are applied to channelized power series waterfalls) in this investigation. Wavelet analysis can be thought of as a generalization of Fourier analysis that allows us to examine non-stationary characteristics of the spectra. The survey included both short (10 minute), long (60 minute), and follow-up observations on candidate targets. Analysis so far has identified three variable sources out of 43 distinct objects that were observed. These objects exhibit significant variation on the order of several minutes, are consistent in follow-up observations, and we have ruled out instrumental variation. Future and ongoing work includes identifying the source of this variation as intrinsic to the source or a property of the ISM. Shorter time-scales will be investigated using a combination of techniques, including total power variation, pulse searching (in an attempt to find pulsars), and phase-shift demodulation techniques. The case for SETI analysis of these data is given, for example, by Cordes (1993), who suggested that extraterrestrial intelligences could use masers to amplify interstellar signals.This project was funded by the National Science Foundation Grant AST0852095. [1] Weisberg J. M. et al. (2005) Science, 309, 5731. [2] Cordes J. M. (1993) Astron. Soc. Pacific Conf. Series

  16. Short-Term Variability on the Scotian Shelf

    NASA Astrophysics Data System (ADS)

    Greenan, B.; Petrie, B.; Harrison, G.; Oakey, N.; Strain, P.

    2002-12-01

    The traditional view of the production cycle on the continental shelf of Nova Scotia features a spring bloom followed by a period of low production and a less intense fall bloom. The annual cycle of primary productivity thus has a large, low frequency component. However, there is increasing evidence that the production cycle has significant variability on shorter time scales. Physical, chemical and biological variability on the Scotian Shelf is examined on a daily to weekly timescale. This is accomplished through the use of a newly developed mooring platform (SeaHorse) that uses surface wave energy to enable the instrument to climb down the mooring wire and then float upwards while sampling the water column. This provides bi-hourly profiles of temperature, salinity, pressure and chlorophyll at one location over month-long periods. Results from the three-week deployment in October 2000 indicate a subsurface chlorophyll maximum below the pycnocline during the first part of the time series. An event occurred in mid-October during which the temperature, salinity and density iso-surfaces rose approximately 25 m. During this event, a small bloom, with peak chlorophyll concentrations of about 2 mg m-3 and duration of several days, began as nutrients were brought into the upper part of the water column by upwelling-favorable winds. SeaWiFS ocean color satellite images were valuable in providing a spatial context for chlorophyll concentrations, however, the lack of temporal resolution due to poor quality images means that this data set provided limited information for short-term chlorophyll variability. Gradient Richardson Numbers were estimated for 2 m vertical bins using SeaHorse CTD data and nearby ADCP current measurements. A trend of decreasing Ri in the ocean mixed layer with increasing surface wind stress is suggested.

  17. Short-term climate variability and atmospheric teleconnections from satellite-observed outgoing longwave radiation. I Simultaneous relationships. II - Lagged correlations

    NASA Technical Reports Server (NTRS)

    Lau, K.-M.; Chan, P. H.

    1983-01-01

    Attention is given to the low-frequency variability of outgoing longwave radiation (OLR) fluctuations, their possible correlations over different parts of the globe, and their relationships with teleconnections obtained from other meteorological parameters, for example, geopotential and temperature fields. Simultaneous relationships with respect to the Southern Oscillation (Namais, 1978; Barnett, 1981) signal and the reference OLR fluctuation over the equatorial central Pacific are investigated. Emphasis is placed on the relative importance of the Southern Oscillation (SO) signal over preferred regions. Using lag cross-correlation statistics, possible lagged relationships between the tropics and midlatitudes and their relationships with the SO are then investigated. Only features that are consistent with present knowledge of the dynamics of the system are emphasized. Certain features which may not meet rigorous statistical significance tests but yet are either expected a priori from independent observations or are predicted from dynamical theories are also explored.

  18. Short-term nonmigrating tide variability in the mesosphere, thermosphere, and ionosphere

    NASA Astrophysics Data System (ADS)

    Pedatella, N. M.; Oberheide, J.; Sutton, E. K.; Liu, H.-L.; Anderson, J. L.; Raeder, K.

    2016-04-01

    The intraseasonal variability of the eastward propagating nonmigrating diurnal tide with zonal wave number 3 (DE3) during 2007 in the mesosphere, ionosphere, and thermosphere is investigated using a whole atmosphere model reanalysis and satellite observations. The atmospheric reanalysis is based on implementation of data assimilation in the Whole Atmosphere Community Climate Model (WACCM) using the Data Assimilation Research Testbed (DART) ensemble Kalman filter. The tidal variability in the WACCM+DART reanalysis is compared to the observed variability in the mesosphere and lower thermosphere (MLT) based on the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) observations, in the ionosphere based on Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) observations, and in the upper thermosphere (˜475 km) based on Gravity Recovery and Climate Experiment (GRACE) neutral density observations. To obtain the short-term DE3 variability in the MLT and upper thermosphere, we apply the method of tidal deconvolution to the TIMED/SABER observations and consider the difference in the ascending and descending longitudinal wave number 4 structure in the GRACE observations. The results reveal that tidal amplitude changes of 5-10 K regularly occur on short timescales (˜10-20 days) in the MLT. Similar variability occurs in the WACCM+DART reanalysis and TIMED/SABER observations, demonstrating that the short-term variability can be captured in whole atmosphere models that employ data assimilation and in observations by the technique of tidal deconvolution. The impact of the short-term DE3 variability in the MLT on the ionosphere and thermosphere is also clearly evident in the COSMIC and GRACE observations. Analysis of the troposphere forcing in WACCM+DART and simulations of the Global Scale Wave Model (GSWM) show that the short-term DE3 variability in the MLT is

  19. Short-term Variability of Extinction by Broadband Stellar Photometry

    SciTech Connect

    Musat, I.C.; Ellingson, R.G.

    2005-03-18

    Aerosol optical depth variation over short-term time intervals is determined from broadband observations of stars with a whole sky imager. The main difficulty in such measurements consists of accurately separating the star flux value from the non-stellar diffuse skylight. Using correction method to overcome this difficulty, the monochromatic extinction at the ground due to aerosols is extracted from heterochromatic measurements. A form of closure is achieved by comparison with simultaneous or temporally close measurements with other instruments, and the total error of the method, as a combination of random error of measurements and systematic error of calibration and model, is assessed as being between 2.6 and 3% rms.

  20. Acute psychological stress induces short-term variable immune response.

    PubMed

    Breen, Michael S; Beliakova-Bethell, Nadejda; Mujica-Parodi, Lilianne R; Carlson, Joshua M; Ensign, Wayne Y; Woelk, Christopher H; Rana, Brinda K

    2016-03-01

    In spite of advances in understanding the cross-talk between the peripheral immune system and the brain, the molecular mechanisms underlying the rapid adaptation of the immune system to an acute psychological stressor remain largely unknown. Conventional approaches to classify molecular factors mediating these responses have targeted relatively few biological measurements or explored cross-sectional study designs, and therefore have restricted characterization of stress-immune interactions. This exploratory study analyzed transcriptional profiles and flow cytometric data of peripheral blood leukocytes with physiological (endocrine, autonomic) measurements collected throughout the sequence of events leading up to, during, and after short-term exposure to physical danger in humans. Immediate immunomodulation to acute psychological stress was defined as a short-term selective up-regulation of natural killer (NK) cell-associated cytotoxic and IL-12 mediated signaling genes that correlated with increased cortisol, catecholamines and NK cells into the periphery. In parallel, we observed down-regulation of innate immune toll-like receptor genes and genes of the MyD88-dependent signaling pathway. Correcting gene expression for an influx of NK cells revealed a molecular signature specific to the adrenal cortex. Subsequently, focusing analyses on discrete groups of coordinately expressed genes (modules) throughout the time-series revealed immune stress responses in modules associated to immune/defense response, response to wounding, cytokine production, TCR signaling and NK cell cytotoxicity which differed between males and females. These results offer a spring-board for future research towards improved treatment of stress-related disease including the impact of stress on cardiovascular and autoimmune disorders, and identifies an immune mechanism by which vulnerabilities to these diseases may be gender-specific. PMID:26476140

  1. SHORT-TERM Halpha VARIABILITY IN M DWARFS

    SciTech Connect

    Lee, Khee-Gan; Knapp, Gillian R.; Berger, Edo E-mail: eberger@cfa.harvard.ed

    2010-01-10

    We spectroscopically study the variability of Halpha emission in mid- to late-M dwarfs on timescales of approx0.1-1 hr as a proxy for magnetic variability. About 80% of our sample exhibits statistically significant variability on the full range of timescales probed by the observations, and with amplitude ratios in the range of approx1.2-4. No events with an order of magnitude increase in Halpha luminosity were detected, indicating that their rate is approx<0.05 hr{sup -1} (95% confidence level). We find a clear increase in variability with later spectral type, despite an overall decrease in Halpha 'activity' (i.e., L{sub Ha}lpha/L{sub bol}). For the ensemble of Halpha variability events, we find a nearly order of magnitude increase in the number of events from timescales of about 10-30 minutes, followed by a roughly uniform distribution at longer durations. The event amplitudes follow an exponential distribution with a characteristic scale of Max(EW)/Min(EW) - 1 approx 0.7. This distribution predicts a low rate of approx10{sup -6} hr{sup -1} for events with Max(EW)/Min(EW) approx> 10, but serendipitous detections of such events in the past suggest that they represent a different distribution. Finally, we find a possible decline in the amplitude of events with durations of approx>0.5 hr, which may point to a typical energy release in Halpha events for each spectral type (E{sub Ha}lpha approx L{sub Ha}lpha x t approx const). Longer observations of individual active objects are required to further investigate this possibility. Similarly, a larger sample may shed light on whether Halpha variability correlates with properties such as age or rotation velocity.

  2. Short Term Weather Forecasting and Long Term Climate Predictions in Mesoamerica

    NASA Astrophysics Data System (ADS)

    Hardin, D. M.; Daniel, I.; Mecikalski, J.; Graves, S.

    2008-05-01

    The SERVIR project utilizes several predictive models to support regional monitoring and decision support in Mesoamerica. Short term forecasts ranging from a few hours to several days produce more than 30 data products that are used daily by decision makers, as well as news organizations in the region. The forecast products can be visualized in both two and three dimensional viewers such as Google Maps and Google Earth. Other viewers developed specifically for the Mesoamerican region by the University of Alabama in Huntsville and the Institute for the Application of Geospatial Technologies in Auburn New York can also be employed. In collaboration with the NASA Short Term Prediction Research and Transition (SpoRT) Center SERVIR utilizes the Weather Research and Forecast (WRF) model to produce short-term (24 hr) regional weather forecasts twice a day. Temperature, precipitation, wind, and other variables are forecast in 10km and 30km grids over the Mesoamerica region. Using the PSU/NCAR Mesoscale Model, known as MM5, SERVIR produces 48 hour- forecasts of soil temperature, two meter surface temperature, three hour accumulated precipitation, winds at different heights, and other variables. These are forecast hourly in 9km grids. Working in collaboration with the Atmospheric Science Department of the University of Alabama in Huntsville produces a suite of short-term (0-6 hour) weather prediction products are generated. These "convective initiation" products predict the onset of thunderstorm rainfall and lightning within a 1-hour timeframe. Models are also employed for long term predictions. The SERVIR project, under USAID funding, has developed comprehensive regional climate change scenarios of Mesoamerica for future years: 2010, 2015, 2025, 2050, and 2099. These scenarios were created using the Pennsylvania State University/National Center for Atmospheric Research (MM5) model and processed on the Oak Ridge National Laboratory Cheetah supercomputer. The goal of these

  3. Short-term Time Step Convergence in a Climate Model

    SciTech Connect

    Wan, Hui; Rasch, Philip J.; Taylor, Mark; Jablonowski, Christiane

    2015-02-11

    A testing procedure is designed to assess the convergence property of a global climate model with respect to time step size, based on evaluation of the root-mean-square temperature difference at the end of very short (1 h) simulations with time step sizes ranging from 1 s to 1800 s. A set of validation tests conducted without sub-grid scale parameterizations confirmed that the method was able to correctly assess the convergence rate of the dynamical core under various configurations. The testing procedure was then applied to the full model, and revealed a slow convergence of order 0.4 in contrast to the expected first-order convergence. Sensitivity experiments showed without ambiguity that the time stepping errors in the model were dominated by those from the stratiform cloud parameterizations, in particular the cloud microphysics. This provides a clear guidance for future work on the design of more accurate numerical methods for time stepping and process coupling in the model.

  4. Short-term Time Step Convergence in a Climate Model

    DOE PAGESBeta

    Wan, Hui; Rasch, Philip J.; Taylor, Mark; Jablonowski, Christiane

    2015-02-11

    A testing procedure is designed to assess the convergence property of a global climate model with respect to time step size, based on evaluation of the root-mean-square temperature difference at the end of very short (1 h) simulations with time step sizes ranging from 1 s to 1800 s. A set of validation tests conducted without sub-grid scale parameterizations confirmed that the method was able to correctly assess the convergence rate of the dynamical core under various configurations. The testing procedure was then applied to the full model, and revealed a slow convergence of order 0.4 in contrast to themore » expected first-order convergence. Sensitivity experiments showed without ambiguity that the time stepping errors in the model were dominated by those from the stratiform cloud parameterizations, in particular the cloud microphysics. This provides a clear guidance for future work on the design of more accurate numerical methods for time stepping and process coupling in the model.« less

  5. Short-term climatic fluctuations forced by thermal anomalies

    NASA Technical Reports Server (NTRS)

    Hanna, A. F.

    1982-01-01

    A two level, global, spectral model using pressure as a vertical coordinate was developed. The system of equations describing the model is nonlinear and quasi-geostrophic (linear balance). Static stability is variable in the model. A moisture budget is calculated in the lower layer only. Convective adjustment is used to avoid supercritical temperature lapse rates. The mechanical forcing of topography is introduced as a vertical velocity at the lower boundary. Solar forcing is specified assuming a daily mean zenith angle. The differential diabatic heating between land and sea is paramterized. On land and sea ice surfaces, a steady state thermal energy equation is solved to calculate the surface temperature. On the oceans, the sea surface temperature is specified as the climatological average for January. The model is used to simulate the January, February and March circulations.

  6. The structure of short-term rainfall: trends in variability studied with data from Portugal

    NASA Astrophysics Data System (ADS)

    de Lima, M. I. P.; Coelho, M. F. E. S.; Carvalho, S. C. P.; de Lima, J. L. M. P.

    2009-04-01

    The very important impact of rain on society (e.g. urban drainage), economic activities (e.g. agriculture), land use, water resources and ecosystems justifies the continued exploration of the variability in this process. Increased rainfall variability in recent years has already been reported by different studies, in particular on the basis on annual and monthly point data, and for different geographical locations. However, for some engineering applications, the behaviour of rainfall at different scales is essential for using many hydrological models and hydraulic design approaches that rely on the characterization of rain at specific (smaller) temporal scales. This work investigates recent trends in the temporal structure of rainfall using short-term point data from Portugal. The data set includes a significant number of stations scattered over the territory. Several rainfall indices and other parameters are analysed with statistical methods that allow determining the statistical significance of the results; these include the study of partial trends. In order to take into account seasonality and serial correlation, the different months of the year were analysed separately. The analyses lead to a characterization of changes in the properties of short-term rainfall over time, particularly within the year. There are also differences over the territory. Both are strengthening the well-known strong seasonal and regional character of rain in Portugal. The relevant factors affecting rain variability, in time and space, can lead to contrasting statistics which should be carefully taken into account in design procedures and decision making processes. This is particularly relevant in regions where the rainfall climate exhibits non-homogeneous structure. This work has been carried out under research project PTDC/GEO/73114/2006, funded by the Portuguese Foundation for Science and Technology.

  7. Metabolic Syndrome and Short-Term Heart Rate Variability in Adults with Intellectual Disabilities

    ERIC Educational Resources Information Center

    Chang, Yaw-Wen; Lin, Jin-Ding; Chen, Wei-Liang; Yen, Chia-Feng; Loh, Ching-Hui; Fang, Wen-Hui; Wu, Li-Wei

    2012-01-01

    Metabolic syndrome (MetS) increases the risk of cardiovascular events. Heart rate variability (HRV) represents autonomic functioning, and reduced HRV significantly increases cardiovascular mortality. The aims of the present paper are to assess the prevalence of MetS in adults with intellectual disabilities (ID), the difference in short-term HRV…

  8. Separate estimation of long- and short-term systolic blood pressure variability from photoplethysmograph.

    PubMed

    Kondo, Riho; Bhuiyan, Md Shoaib; Kawanaka, Haruki; Oguri, Koji

    2014-01-01

    This paper proposed a method to monitor systolic blood pressure (BP) variability without using a cuff during the daytime. In this method, BP variability of long-term and short-term were separated and estimated respectively from features of phoplethysmograph (PPG) through the use of a frequency filter. Then, total variability was obtained from the combination of long-term and short-term. BP by using a cuff (ground truth) and PPG of nine healthy young subjects were measured during the daytime; then BP variability was estimated from PPG to verify the validity of our method. As a result, the correlation coefficients between measured BP variability and estimated BP variability was improved from r = 0.35 in previous method to r = 0.41 in proposed method. In particular, the estimation results in short-term BP variability showed good accuracy (r = 0.67). This method of estimating BP variability has the potential to be a simple and continuous BP monitoring system during the daytime. PMID:25570338

  9. Evolution of extreme temperature events in short term climate projection for Iberian Peninsula.

    NASA Astrophysics Data System (ADS)

    Rodriguez, Alfredo; Tarquis, Ana M.; Sanchez, Enrique; Dosio, Alessandro; Ruiz-Ramos, Margarita

    2014-05-01

    Extreme events of maximum and minimum temperatures are a main hazard for agricultural production in Iberian Peninsula. For this purpose, in this study we analyze projections of their evolution that could be valid for the next decade, represented in this study by the 30-year period 2004-2034 (target period). For this purpose two kinds of data were used in this study: 1) observations from the station network of AEMET (Spanish National Meteorological Agency) for five Spanish locations, and 2) simulated data at a resolution of 50 ×50 km horizontal grid derived from the outputs of twelve Regional Climate Models (RCMs) taken from project ENSEMBLES (van der Linden and Mitchell, 2009), with a bias correction (Dosio and Paruolo, 2011; Dosio et al., 2012) regarding the observational dataset Spain02 (Herrera et al., 2012). To validate the simulated climate, the available period of observations was compared to a baseline period (1964-1994) of simulated climate for all locations. Then, to analyze the changes for the present/very next future, probability of extreme temperature events for 2004-2034 were compared to that of the baseline period. Although only minor changes are expected, small variations in variability may have a significant impact in crop performance. The objective of the work is to evaluate the utility of these short term projections for potential users, as for instance insurance companies. References Dosio A. and Paruolo P., 2011. Bias correction of the ENSEMBLES high-resolution climate change projections for use by impact models: Evaluation on the present climate. Journal of Geophysical Research, VOL. 116,D16106, doi:10.1029/2011JD015934 Dosio A., Paruolo P. and Rojas R., 2012. Bias correction of the ENSEMBLES high resolution climate change projections for use by impact models: Analysis of the climate change signal. Journal of Geophysical Research,Volume 117, D17, doi: 0.1029/2012JD017968 Herrera et. al. (2012) Development and Analysis of a 50 year high

  10. Short-term climate changes in the Holsteinian Interglacial - EGU2012-132

    NASA Astrophysics Data System (ADS)

    Nitychoruk, J.; Bińka, K.; Ruppert, H.; Tudryn, A.

    2012-04-01

    Oxygen and carbon stable isotopes from fossil lake sediments of the Holsteinian age (eastern Poland) give evidence for the abrupt climate shifts in this interglacial that coincide with the changes in vegetation inferred from palaeobotanical data. Especially changes of the stable isotope ratios as well as decrease in the carbonate content in the deposits and increase in silicate redeposited from the area around the lake are synchronous with the short-term climatic deteriorations within the interglacial pollen flora. Two distinct climate shifts are recorded in the Holsteinian. The first one is marked by the very characteristic pine-birch cold phase after the yew (Taxus) domination that is reported from numerous pollen diagrams from Central Europe. This distinct cooling resembles a phenomenon known as 8.2 ka event in the Holocene, when waters of the Agassiz Lake in North America drained into the Atlantic Ocean (Koutsodendris et al. 2010). Enormous volumes of freshwater from melting of the Laurentian ice-sheet caused disturbances in the Gulf Stream and as a result some decrease in regional temperatures. The second distinct cooling of a lower rank took place within the younger part of the climatic optimum of the Holsteinian. It is relatively less known, because most often pollen records lack sufficient temporal resolution needed to identify this event. A well documented cooling in the Holsteinian deposits from Dethlingen, northern Germany (Koutsodendris et al. 2010) and from the Ossówka, eastern Poland (Nitychoruk et al. 2005) are exceptional. In the sequence from Dethlingen, a distinct increase in the percentage of pioneer trees is accompanied by a lower content of temperate taxa. At Ossówka, the shift of climate is noted as the rise of ratio of oxygen and carbon isotopes. According to Nitychoruk (2000) the cold event is coincident with volcanic eruptions evidenced by volcanic ash found in the lake deposits at that time. Literature Koutsodendris, A., Müller, U

  11. Ketamine and xylazine combinations for short-term immobilization of wild variable flying foxes (Pteropus hypomelanus).

    PubMed

    Sohayati, A R; Zaini, C M; Hassan, L; Epstein, J; Siti Suri, A; Daszak, Peter; Sharifah, S H

    2008-12-01

    Collection of biological samples from pteropid bats requires chemical restraint of the bats to minimize risks to humans and stress to the bat. The effectiveness of an intravenous combination of ketamine and xylazine for short-term restraint of wild-caught variable flying foxes (Pteropus hypomelanus) in a field situation was evaluated. Eight adult male variable flying foxes were injected intravenously with 0.1 ml of ketamine and xylaxine containing 5 mg of ketamine and 1 mg of xylazine. The mean induction time was 80 +/- 20 sec, and mean immobilization time was 26 +/- 10 min. The ketamine-xylazine combination used in this study produced effective short-term immobilization of wild variable flying foxes for the collection of biological samples. PMID:19110718

  12. Fetal autonomic brain age scores, segmented heart rate variability analysis, and traditional short term variability.

    PubMed

    Hoyer, Dirk; Kowalski, Eva-Maria; Schmidt, Alexander; Tetschke, Florian; Nowack, Samuel; Rudolph, Anja; Wallwitz, Ulrike; Kynass, Isabelle; Bode, Franziska; Tegtmeyer, Janine; Kumm, Kathrin; Moraru, Liviu; Götz, Theresa; Haueisen, Jens; Witte, Otto W; Schleußner, Ekkehard; Schneider, Uwe

    2014-01-01

    Disturbances of fetal autonomic brain development can be evaluated from fetal heart rate patterns (HRP) reflecting the activity of the autonomic nervous system. Although HRP analysis from cardiotocographic (CTG) recordings is established for fetal surveillance, temporal resolution is low. Fetal magnetocardiography (MCG), however, provides stable continuous recordings at a higher temporal resolution combined with a more precise heart rate variability (HRV) analysis. A direct comparison of CTG and MCG based HRV analysis is pending. The aims of the present study are: (i) to compare the fetal maturation age predicting value of the MCG based fetal Autonomic Brain Age Score (fABAS) approach with that of CTG based Dawes-Redman methodology; and (ii) to elaborate fABAS methodology by segmentation according to fetal behavioral states and HRP. We investigated MCG recordings from 418 normal fetuses, aged between 21 and 40 weeks of gestation. In linear regression models we obtained an age predicting value of CTG compatible short term variability (STV) of R (2) = 0.200 (coefficient of determination) in contrast to MCG/fABAS related multivariate models with R (2) = 0.648 in 30 min recordings, R (2) = 0.610 in active sleep segments of 10 min, and R (2) = 0.626 in quiet sleep segments of 10 min. Additionally segmented analysis under particular exclusion of accelerations (AC) and decelerations (DC) in quiet sleep resulted in a novel multivariate model with R (2) = 0.706. According to our results, fMCG based fABAS may provide a promising tool for the estimation of fetal autonomic brain age. Beside other traditional and novel HRV indices as possible indicators of developmental disturbances, the establishment of a fABAS score normogram may represent a specific reference. The present results are intended to contribute to further exploration and validation using independent data sets and multicenter research structures. PMID:25505399

  13. Jensen's Inequality and the Impact of Short-Term Environmental Variability on Long-Term Population Growth Rates.

    PubMed

    Pickett, Evan J; Thomson, David L; Li, Teng A; Xing, Shuang

    2015-01-01

    It is well established in theory that short-term environmental fluctuations could affect the long-term growth rates of wildlife populations, but this theory has rarely been tested and there remains little empirical evidence that the effect is actually important in practice. Here we develop models to quantify the effects of daily, seasonal, and yearly temperature fluctuations on the average population growth rates, and we apply them to long-term data on the endangered Black-faced Spoonbill (Platalea minor); an endothermic species whose population growth rates follow a concave relationship with temperature. We demonstrate for the first time that the current levels of temperature variability, particularly seasonal variability, are already large enough to substantially reduce long-term population growth rates. As the climate changes, our results highlight the importance of considering the ecological effects of climate variability and not just average conditions. PMID:26352857

  14. Short-term optical variability of high-redshift quasi-stellar objects

    NASA Astrophysics Data System (ADS)

    Bachev, R.; Strigachev, A.; Semkov, E.

    2005-04-01

    In this paper we present the results of a search for short-term variability in the optical band of selected high-luminosity, high-redshift radio-quiet quasars. Each quasar has been monitored typically for 2-4 h with a time resolution of 2-5 min and a photometric accuracy of about 0.01-0.02 mag. As a result of the significant redshift (z > 2), the covered wavelength range falls into the ultraviolet region (typically 1500-2500 Å). We have found no statistical evidence for any continuum variations larger than 0.01-0.02 mag for any of the monitored objects. Our results suggest that the presence of a short-term variability in radio-quiet quasars is unlikely even in the ultraviolet region, contrary to reports by other authors. This conclusion holds true at least for high-luminosity (large black hole mass and accretion rate?) objects. The results are consistent with the idea that significant short-term (less than 1 h) variations in active galactic nuclei, where observed, should be attributed primarily to processes in a relativistic jet.

  15. Implications of Wide-Area Geographic Diversity for Short- Term Variability of Solar Power

    SciTech Connect

    Mills, Andrew; Wiser, Ryan

    2010-08-23

    Worldwide interest in the deployment of photovoltaic generation (PV) is rapidly increasing. Operating experience with large PV plants, however, demonstrates that large, rapid changes in the output of PV plants are possible. Early studies of PV grid impacts suggested that short-term variability could be a potential limiting factor in deploying PV. Many of these early studies, however, lacked high-quality data from multiple sites to assess the costs and impacts of increasing PV penetration. As is well known for wind, accounting for the potential for geographic diversity can significantly reduce the magnitude of extreme changes in aggregated PV output, the resources required to accommodate that variability, and the potential costs of managing variability. We use measured 1-min solar insolation for 23 time-synchronized sites in the Southern Great Plains network of the Atmospheric Radiation Measurement program and wind speed data from 10 sites in the same network to characterize the variability of PV with different degrees of geographic diversity and to compare the variability of PV to the variability of similarly sited wind. The relative aggregate variability of PV plants sited in a dense 10 x 10 array with 20 km spacing is six times less than the variability of a single site for variability on time scales less than 15-min. We find in our analysis of wind and PV plants similarly sited in a 5 x 5 grid with 50 km spacing that the variability of PV is only slightly more than the variability of wind on time scales of 5-15 min. Over shorter and longer time scales the level of variability is nearly identical. Finally, we use a simple approximation method to estimate the cost of carrying additional reserves to manage sub-hourly variability. We conclude that the costs of managing the short-term variability of PV are dramatically reduced by geographic diversity and are not substantially different from the costs for managing the short-term variability of similarly sited wind in

  16. Role of Satellite Rainfall Information in Improving Understanding of the Dynamical Link Between the Tropics and Extratropics Prospects of Improved Forecasts of Weather and Short-Term Climate Variability on Sub-Seasonal Time Scales

    NASA Technical Reports Server (NTRS)

    Hou, Arthur Y.

    2002-01-01

    The tropics and extratropics are two dynamically distinct regimes. The coupling between these two regimes often defies simple analytical treatment. Progress in understanding of the dynamical interaction between the tropics and extratropics relies on better observational descriptions to guide theoretical development. However, global analyses currently contain significant errors in primary hydrological variables such as precipitation, evaporation, moisture, and clouds, especially in the tropics. Tropical analyses have been shown to be sensitive to parameterized precipitation processes, which are less than perfect, leading to order-one discrepancies between estimates produced by different data assimilation systems. One strategy for improvement is to assimilate rainfall observations to constrain the analysis and reduce uncertainties in variables physically linked to precipitation. At the Data Assimilation Office at the NASA Goddard Space Flight Center, we have been exploring the use of tropical rain rates derived from the TRMM Microwave Imager (TMI) and the Special Sensor Microwave/ Imager (SSM/I) instruments in global data assimilation. Results show that assimilating these data improves not only rainfall and moisture fields but also related climate parameters such as clouds and radiation, as well as the large-scale circulation and short-range forecasts. These studies suggest that assimilation of microwave rainfall observations from space has the potential to significantly improve the quality of 4-D assimilated datasets for climate investigations (Hou et al. 2001). In the next few years, there will be a gradual increase in microwave rain products available from operational and research satellites, culminating to a target constellation of 9 satellites to provide global rain measurements every 3 hours with the proposed Global Precipitation Measurement (GPM) mission in 2007. Continued improvements in assimilation methodology, rainfall error estimates, and model

  17. Ultra-Short-Term Heart Rate Variability is Sensitive to Training Effects in Team Sports Players.

    PubMed

    Nakamura, Fabio Y; Flatt, Andrew A; Pereira, Lucas A; Ramirez-Campillo, Rodrigo; Loturco, Irineu; Esco, Michael R

    2015-09-01

    The aim of this study was to test the possibility of the ultra-short-term lnRMSSD (measured in 1-min post-1-min stabilization period) to detect training induced adaptations in futsal players. Twenty-four elite futsal players underwent HRV assessments pre- and post-three or four weeks preseason training. From the 10-min HRV recording period, lnRMSSD was analyzed in the following time segments: 1) from 0-5 min (i.e., stabilization period); 2) from 0-1 min; 1-2 min; 2-3 min; 3-4 min; 4-5 min and; 3) from 5-10 min (i.e., criterion period). The lnRMSSD was almost certainly higher (100/00/00) using the magnitude-based inference in all periods at the post- moment. The correlation between changes in ultra-short-term lnRMSSD (i.e., 0-1 min; 1-2 min; 2-3 min; 3-4 min; 4-5 min) and lnRMSSDCriterion ranged between 0.45-0.75, with the highest value (p = 0.75; 90% CI: 0.55 - 0.85) found between ultra-short-term lnRMDSSD at 1-2 min and lnRMSSDCriterion. In conclusion, lnRMSSD determined in a short period of 1-min is sensitive to training induced changes in futsal players (based on the very large correlation to the criterion measure), and can be used to track cardiac autonomic adaptations. Key pointsThe ultra-short-term (1 min) natural log of the root-mean-square difference of successive normal RR intervals (lnRMSSD) is sensitive to training effects in futsal playersThe ultra-short-term lnRMSSD may simplify the assessment of the cardiac autonomic changes in the field compared to the traditional and lengthier (10 min duration) analysisCoaches are encouraged to implement the ultra-short-term heart rate variability in their routines to monitor team sports athletes. PMID:26336347

  18. Ultra-Short-Term Heart Rate Variability is Sensitive to Training Effects in Team Sports Players

    PubMed Central

    Nakamura, Fabio Y.; Flatt, Andrew A.; Pereira, Lucas A.; Ramirez-Campillo, Rodrigo; Loturco, Irineu; Esco, Michael R.

    2015-01-01

    The aim of this study was to test the possibility of the ultra-short-term lnRMSSD (measured in 1-min post-1-min stabilization period) to detect training induced adaptations in futsal players. Twenty-four elite futsal players underwent HRV assessments pre- and post-three or four weeks preseason training. From the 10-min HRV recording period, lnRMSSD was analyzed in the following time segments: 1) from 0-5 min (i.e., stabilization period); 2) from 0-1 min; 1-2 min; 2-3 min; 3-4 min; 4-5 min and; 3) from 5-10 min (i.e., criterion period). The lnRMSSD was almost certainly higher (100/00/00) using the magnitude-based inference in all periods at the post- moment. The correlation between changes in ultra-short-term lnRMSSD (i.e., 0-1 min; 1-2 min; 2-3 min; 3-4 min; 4-5 min) and lnRMSSDCriterion ranged between 0.45-0.75, with the highest value (p = 0.75; 90% CI: 0.55 – 0.85) found between ultra-short-term lnRMDSSD at 1-2 min and lnRMSSDCriterion. In conclusion, lnRMSSD determined in a short period of 1-min is sensitive to training induced changes in futsal players (based on the very large correlation to the criterion measure), and can be used to track cardiac autonomic adaptations. Key points The ultra-short-term (1 min) natural log of the root-mean-square difference of successive normal RR intervals (lnRMSSD) is sensitive to training effects in futsal players The ultra-short-term lnRMSSD may simplify the assessment of the cardiac autonomic changes in the field compared to the traditional and lengthier (10 min duration) analysis Coaches are encouraged to implement the ultra-short-term heart rate variability in their routines to monitor team sports athletes PMID:26336347

  19. A Meta-Analysis of the Impact of Short-Term Sleep Deprivation on Cognitive Variables

    PubMed Central

    Lim, Julian; Dinges, David F.

    2012-01-01

    A substantial amount of research has been conducted in an effort to understand the impact of short-term (<48 hr) total sleep deprivation (SD) on outcomes in various cognitive domains. Despite this wealth of information, there has been disagreement on how these data should be interpreted, arising in part because the relative magnitude of effect sizes in these domains is not known. To address this question, we conducted a meta-analysis to discover the effects of short-term SD on both speed and accuracy measures in 6 cognitive categories: simple attention, complex attention, working memory, processing speed, short-term memory, and reasoning. Seventy articles containing 147 cognitive tests were found that met inclusion criteria for this study. Effect sizes ranged from small and nonsignificant (reasoning accuracy: ḡ = −0.125, 95% CI [−0.27, 0.02]) to large (lapses in simple attention: ḡ = −0.776, 95% CI [−0.96, −0.60], p < .001). Across cognitive domains, significant differences were observed for both speed and accuracy; however, there were no differences between speed and accuracy measures within each cognitive domain. Of several moderators tested, only time awake was a significant predictor of between-studies variability, and only for accuracy measures, suggesting that heterogeneity in test characteristics may account for a significant amount of the remaining between-studies variance. The theoretical implications of these findings for the study of SD and cognition are discussed. PMID:20438143

  20. Annual dynamics of North Sea bacterioplankton: seasonal variability superimposes short-term variation.

    PubMed

    Lucas, Judith; Wichels, Antje; Teeling, Hanno; Chafee, Meghan; Scharfe, Mirco; Gerdts, Gunnar

    2015-09-01

    The dynamics of coastal marine microbial communities are driven by seasonally changing abiotic and biotic factors as well as by rapidly occurring short-term changes such as river fresh water influxes or phytoplankton blooms. We examined the variability of the free-living bacterioplankton at Helgoland Roads (German Bight, North Sea) over a period of one year with high temporal and taxonomic resolution to reveal variation patterns and main influencing factors. 16S rRNA gene tag sequencing of the bacterioplankton community hints at annual recurrence and resilience of few main taxa belonging to Alphaproteobacteria, Betaproteobacteria, Flavobacteriia, Acidimicrobiia and Thermoplasmata. Multiple regression analyses with various environmental factors revealed changes in water current patterns and resulting phytoplankton blooms as the main driving factors for short-term variation and temperature as the overlying factor for seasonal variation. Comparison of bacterioplankton successions during spring and summer phytoplankton blooms revealed the same dominating Flavobacteriia operational taxonomic units (OTUs) but shifts in Roseobacter related OTUs (Alphaproteobacteria) and SAR92 clade members (Gammaproteobacteria). Network analysis suggests that during spring and summer phytoplankton blooms temperature-dependent guilds are formed. In conclusion, our data imply that short-term bacterioplankton successions in response to phytoplankton blooms are indirectly affected by temperature, which is a major niche-defining factor in the German Bight. PMID:26298013

  1. Increased Short-Term Beat-To-Beat Variability of QT Interval in Patients with Acromegaly.

    PubMed

    Orosz, Andrea; Csajbók, Éva; Czékus, Csilla; Gavallér, Henriette; Magony, Sándor; Valkusz, Zsuzsanna; Várkonyi, Tamás T; Nemes, Attila; Baczkó, István; Forster, Tamás; Wittmann, Tibor; Papp, Julius Gy; Varró, András; Lengyel, Csaba

    2015-01-01

    Cardiovascular diseases, including ventricular arrhythmias are responsible for increased mortality in patients with acromegaly. Acromegaly may cause repolarization abnormalities such as QT prolongation and impairment of repolarization reserve enhancing liability to arrhythmia. The aim of this study was to determine the short-term beat-to-beat QT variability in patients with acromegaly. Thirty acromegalic patients (23 women and 7 men, mean age±SD: 55.7±10.4 years) were compared with age- and sex-matched volunteers (mean age 51.3±7.6 years). Cardiac repolarization parameters including frequency corrected QT interval, PQ and QRS intervals, duration of terminal part of T waves (Tpeak-Tend) and short-term variability of QT interval were evaluated. All acromegalic patients and controls underwent transthoracic echocardiographic examination. Autonomic function was assessed by means of five standard cardiovascular reflex tests. Comparison of the two groups revealed no significant differences in the conventional ECG parameters of repolarization (QT: 401.1±30.6 ms vs 389.3±16.5 ms, corrected QT interval: 430.1±18.6 ms vs 425.6±17.3 ms, QT dispersion: 38.2±13.2 ms vs 36.6±10.2 ms; acromegaly vs control, respectively). However, short-term beat-to-beat QT variability was significantly increased in acromegalic patients (4.23±1.03 ms vs 3.02±0.80, P<0.0001). There were significant differences between the two groups in the echocardiographic dimensions (left ventricular end diastolic diameter: 52.6±5.4 mm vs 48.0±3.9 mm, left ventricular end systolic diameter: 32.3±5.2 mm vs 29.1±4.4 mm, interventricular septum: 11.1±2.2 mm vs 8.8±0.7 mm, posterior wall of left ventricle: 10.8±1.4 mm vs 8.9±0.7 mm, P<0.05, respectively). Short-term beat-to-beat QT variability was elevated in patients with acromegaly in spite of unchanged conventional parameters of ventricular repolarization. This enhanced temporal QT variability may be an early indicator of increased liability to

  2. [A Heart Rate Variability Analysis System for Short-term Applications].

    PubMed

    Shi, Bo; Chen, Fasheng; Zhang, Genxuan; Cao, Mingna; Tsau, Young

    2015-08-01

    In this paper, a heart rate variability analysis system is presented for short-term (5 min) applications, which is composed of an electrocardiogram signal acquisition unit and a heart rate variability analysis unit. The electrocardiogram signal acquisition unit adopts various digital technologies, including the low-gain amplifier, the high-resolution analog-digital converter, the real-time digital filter and wireless transmission etc. Meanwhile, it has the advantages of strong anti-interference capacity, small size, light weight, and good portability. The heart rate variability analysis unit is used to complete the R-wave detection and the analyses of time domain, frequency domain and nonlinear indexes, based on the Matlab Toolbox. The preliminary experiments demonstrated that the system was reliable, and could be applied to the heart rate variability analysis at resting, motion states etc. PMID:26710447

  3. Variability of Short-term Precipitation and Runoff in Small Czech Drainage Basins

    NASA Astrophysics Data System (ADS)

    Kavka, Petr; Strouhal, Luděk; Landa, Martin; Neuman, Martin; Kožant, Petr; Muller, Miloslav

    2016-04-01

    The aim of this contribution is to introduce the recently started three year's project named "Variability of Short-term Precipitation and Runoff in Small Czech Drainage Basins and its Influence on Water Resources Management". Its main goal is to elaborate a methodology and online utility for deriving short-term design precipitation series, which could be utilized by a broad community of scientists, state administration as well as design planners. The outcomes of the project will especially be helpful in modelling hydrological or soil erosion problems when designing common measures for promoting water retention or landscape drainage systems in or out of the scope of Landscape consolidation projects. The precipitation scenarios will be derived from 10 years of observed data from point gauging stations and radar data. The analysis is focused on events' return period, rainfall total amount, internal intensity distribution and spatial distribution over the area of Czech Republic. The methodology will account for the choice of the simulation model. Several representatives of practically oriented models will be tested for the output sensitivity to selected precipitation scenario comparing to variability connected with other inputs uncertainty. The variability of the outputs will also be assessed in the context of economic impacts in design of landscape water structures or mitigation measures. The research was supported by the grant QJ1520265 of the Czech Ministry of Agriculture, using data provided by the Czech Hydrometeorological Institute.

  4. Short-term increase of body weight triggers immunological variables in dogs.

    PubMed

    Van de Velde, H; Janssens, G P J; Stuyven, E; Cox, E; Buyse, J; Hesta, M

    2012-01-15

    Overweight in dogs is, as in other companion animals, a major risk factor for several metabolic disorders. However, it is not yet known whether immunity is challenged by increased body weight in dogs. The aim of this study was to investigate the effect of a short-term increase in body weight on immunological variables in adult healthy beagle dogs. Sixteen dogs, divided into a control group (CG) and weight gain group (WGG), were included. During a period of 13 weeks, the CG was fed at maintenance energy requirement (MER), whereas the WGG received a double amount of food. After 13 weeks, blood samples were taken for immunological and biochemical analyses. Weight gain and increased body condition score in the WGG were accompanied by a significant higher leptin concentration. Weight gain increased the number of lymphocytes and immunoglobulins A and M and was responsible for a higher proliferation of peripheral blood mononuclear cells (PBMC). Short-term increase of body weight thus seems to trigger immunological variables in dogs. PMID:22245229

  5. Ambulatory Blood Pressure Monitoring-Derived Short-Term Blood Pressure Variability in Primary Aldosteronism.

    PubMed

    Grillo, Andrea; Bernardi, Stella; Rebellato, Andrea; Fabris, Bruno; Bardelli, Moreno; Burrello, Jacopo; Rabbia, Franco; Veglio, Franco; Fallo, Francesco; Carretta, Renzo

    2015-08-01

    The aim of this study was to investigate the short-term blood pressure (BP) variability (BPV) derived from ambulatory blood pressure monitoring (ABPM) in patients with primary aldosteronism (PA), either idiopathic hyperaldosteronism (IHA) or aldosterone-producing adenoma (APA), in comparison with patients with essential hypertension (EH) and normotensive (NT) controls. Thirty patients with PA (16 with IHA and 14 with APA), 30 patients with EH, and 30 NT controls, matched for sex, age, body mass index, and antihypertensive therapy, were studied. The standard deviation (SD) of 24-hour, daytime, and nighttime BP; 24-hour weighted SD of BP; and 24-hour BP average real variability were not different between patients with PA and those with EH (P=not significant). All BPV indices were higher in patients with PA, either IHA or APA subtypes, and patients with EH, compared with NT controls (P<.001 to P<.05). ABPM-derived short-term BPV is increased in patients with PA, and it may represent an additional cardiovascular risk factor in this disease. The role of aldosterone excess in BPV has to be clarified. PMID:25880017

  6. A Systematic Search for Short-term Variability of EGRET Sources

    NASA Technical Reports Server (NTRS)

    Wallace, P. M.; Griffis, N. J.; Bertsch, D. L.; Hartman, R. C.; Thompson, D. J.; Kniffen, D. A.; Bloom, S. D.

    2000-01-01

    The 3rd EGRET Catalog of High-energy Gamma-ray Sources contains 170 unidentified sources, and there is great interest in the nature of these sources. One means of determining source class is the study of flux variability on time scales of days; pulsars are believed to be stable on these time scales while blazers are known to be highly variable. In addition, previous work has demonstrated that 3EG J0241-6103 and 3EG J1837-0606 are candidates for a new gamma-ray source class. These sources near the Galactic plane display transient behavior but cannot be associated with any known blazers. Although, many instances of flaring AGN have been reported, the EGRET database has not been systematically searched for occurrences of short-timescale (approximately 1 day) variability. These considerations have led us to conduct a systematic search for short-term variability in EGRET data, covering all viewing periods through proposal cycle 4. Six 3EG catalog sources are reported here to display variability on short time scales; four of them are unidentified. In addition, three non-catalog variable sources are discussed.

  7. Short-term spatial and temporal variability in greenhouse gas fluxes in riparian zones.

    PubMed

    Vidon, P; Marchese, S; Welsh, M; McMillan, S

    2015-08-01

    Recent research indicates that riparian zones have the potential to contribute significant amounts of greenhouse gases (GHG: N2O, CO2, CH4) to the atmosphere. Yet, the short-term spatial and temporal variability in GHG emission in these systems is poorly understood. Using two transects of three static chambers at two North Carolina agricultural riparian zones (one restored, one unrestored), we show that estimates of the average GHG flux at the site scale can vary by one order of magnitude depending on whether the mean or the median is used as a measure of central tendency. Because the median tends to mute the effect of outlier points (hot spots and hot moments), we propose that both must be reported or that other more advanced spatial averaging techniques (e.g., kriging, area-weighted average) should be used to estimate GHG fluxes at the site scale. Results also indicate that short-term temporal variability in GHG fluxes (a few days) under seemingly constant temperature and hydrological conditions can be as large as spatial variability at the site scale, suggesting that the scientific community should rethink sampling protocols for GHG at the soil-atmosphere interface to include repeated measures over short periods of time at select chambers to estimate GHG emissions in the field. Although recent advances in technology provide tools to address these challenges, their cost is often too high for widespread implementation. Until technology improves, sampling design strategies will need to be carefully considered to balance cost, time, and spatial and temporal representativeness of measurements. PMID:26169979

  8. A Systematic Search for Short-term Variability of EGRET Sources

    NASA Technical Reports Server (NTRS)

    Wallace, P. M.; Bertsch, D. L.; Bloom, S. D.; Griffis, N. J.; Hunter, S. D.; Kniffen, D. A.; Thompson, D. J.

    1999-01-01

    The 3rd EGRET Catalog contains 170 unidentified high-energy (E>100 MeV) gamma-ray sources, and there is great interest in the nature of these sources. One means of determining sources class is the study of flux variability on time scales of days; pulsars are believed to be stable on these scales while blazars are known to be highly variable. In addition, previous work has led to the discovery of 2CG 135+01 and GRO J1838-04, candidates for a new high-energy gamma-ray source class. These sources display transient behavior but cannot be associated with any known blazars. These considerations have led us to conduct a systematic search for short-term variability in EGRET data, covering all viewing periods through cycle 4. Three unidentified sources show some evidence of variability on short time scales; the source displaying the most convincing variability, 3EG J2006-2321, is not easily identified as a blazar.

  9. Visibility graph analysis of very short-term heart rate variability during sleep

    NASA Astrophysics Data System (ADS)

    Hou, F. Z.; Li, F. W.; Wang, J.; Yan, F. R.

    2016-09-01

    Based on a visibility-graph algorithm, complex networks were constructed from very short-term heart rate variability (HRV) during different sleep stages. Network measurements progressively changed from rapid eye movement (REM) sleep to light sleep and then deep sleep, exhibiting promising ability for sleep assessment. Abnormal activation of the cardiovascular controls with enhanced 'small-world' couplings and altered fractal organization during REM sleep indicates that REM could be a potential risk factor for adverse cardiovascular event, especially in males, older individuals, and people who are overweight. Additionally, an apparent influence of gender, aging, and obesity on sleep was demonstrated in healthy adults, which may be helpful for establishing expected sleep-HRV patterns in different populations.

  10. Rotational Properties of the Haumea Family Members and Candidates: Short-term Variability.

    NASA Astrophysics Data System (ADS)

    Thirouin, Audrey; Sheppard, Scott S.; Noll, Keith S.; Moskovitz, Nicholas A.; Ortiz, Jose Luis; Doressoundiram, Alain

    2016-06-01

    Haumea is one of the most interesting and intriguing trans-Neptunian objects (TNOs). It is a large, bright, fast rotator, and its spectrum indicates nearly pure water ice on the surface. It has at least two satellites and a dynamically related family of more than 10 TNOs with very similar proper orbital parameters and similar surface properties. The Haumean family is the only one currently known in the trans-Neptunian belt. Various models have been proposed, but the formation of the family remains poorly understood. In this work, we have investigated the rotational properties of the family members and unconfirmed family candidates with short-term variability studies, and report the most complete review to date. We present results based on five years of observations and report the short-term variability of five family members and seven candidates. The mean rotational periods, from Maxwellian fits to the frequency distributions, are 6.27 ± 1.19 hr for the confirmed family members, 6.44 ± 1.16 hr for the candidates, and 7.65 ± 0.54 hr for other TNOs (without relation to the family). According to our study, there is a possibility that Haumea family members rotate faster than other TNOs; however, the sample of family members is still too limited for a secure conclusion. We also highlight the fast rotation of 2002 GH32. This object has a 0.36 ± 0.02 mag amplitude lightcurve and a rotational period of about 3.98 hr. Assuming 2002 GH32 is a triaxial object in hydrostatic equilibrium, we derive a lower limit to the density of 2.56 g cm‑3. This density is similar to Haumea’s and much more dense than other small TNO densities.

  11. Short-term variability of microphytobenthic primary production associated with in situ diel and tidal conditions

    NASA Astrophysics Data System (ADS)

    Kwon, Bong-Oh; Khim, Jong Seong; Park, Jinsoon; Ryu, Jongseong; Kang, Seong-Gil; Koh, Chul-Hwan

    2012-10-01

    The short-term variability in microphytobenthos (MPB) production, measured by the oxygen microprofiling method, found under different experimental conditions indicated an endogenous production response reflecting in situ diel and tidal conditions. MPB production was measured for submerged core samples (collected from Daebu mudflat, Korea) at a fixed irradiance and temperature in the laboratory under the conditions of (1) constant light (data-I), (2) light-dark incubation (data-II), and (3) in situ reflected (data-III). The experimental design aimed to characterize within-day, across-day, and long term changes in MPB production. Our results showed that, under constant light conditions for 72 h, temporal fluctuations in MPB production (day:night = 2.4:1) were clearly present for three consecutive days (data-I), indicating a diel rhythm in production. Production increased at the beginning of light exposure, and dramatically decreased at the time of submersion, indicating tide-dependent rhythm in production. Furthermore, over a 10 d period under the same light and temperature conditions, a weakening (declining) trend in production was observed, which was logarithmic with diel fluctuation (r2 = 0.995, p < 0.01). This diel rhythm in production was also observed under an alternating light-dark (L14 h/D10 h) incubation period across an additional 18 d of measurement (data-II). The decline in production was slower, and more linear (r2 = 0.930, p < 0.01) under this condition, as the period of dark incubation (D10 h) seemed to allow the community to recover to a certain level of production. Finally, the effects of tidal condition (spring tide vs. neap tide) and biomass (dense vs. lesser dense) on the short-term (variability of MPB production (data-III) appeared to be negligible when time integrated the production.

  12. Ichno-sedimentological record of short-term climate-controlled redox events and cycles in organic-rich strata

    SciTech Connect

    Savrda, C.E. ); Bottjher, D.J. ); Ozalas, K. )

    1990-05-01

    Reduced rates of biochemical degradation of organic matter in oxygen-depleted marine settings generally result in the accumulation of laminated strata with high hydrocarbon source potential. Periods of improved oxygenation, during which the quantity and quality of organic matter are effectively reduced, are reflected by interbedded bioturbated intervals. Such benthic redox excursions may reflect variable paleooceanographic responses to climatic events or cycles. The potential role of climate in the short-term modulation of source rock potential is exemplified by bioturbated intervals within three predominantly laminated organic-rich units. The Jurassic Posidonia Shale (Germany) contains bioturbated beds whose ichnologic characteristics reflect a spectrum from short, low-magnitude redox events to longer episodes of greater magnitude. The character and distribution of these event beds appear to be controlled by sea level mediated variations in the frequency and intensity of storm-induced basin turnover. Bioturbated beds of the Upper Cretaceous Niobrara Formation (Colorado) are characterized by four oxygen-related ichnocoenoses, the distribution of which reflects cyclic variations in redox conditions. Relationships between paleooxygenation and organic-carbon and carbonate contents, and estimated cycle periodicities, suggest that redox variations were controlled by wet-dry climatic cycles modulated by the Milankovitch cycle of axial precession. Bioturbated beds within slope and basinal facies of the Miocene Monterey Formation (California) are variable in character, reflecting differences in duration and magnitude of associated oxygenation episodes, and may be in response to short-term variations in wind-stress-induced upwelling and/or ice-volume-controlled eustatic sea level changes.

  13. Broadband short term X-ray variability of the quasar PDS 456

    NASA Astrophysics Data System (ADS)

    Matzeu, G. A.; Reeves, J. N.; Nardini, E.; Braito, V.; Costa, M. T.; Tombesi, F.; Gofford, J.

    2016-05-01

    We present a detailed analysis of a recent 500 ks net exposure Suzaku observation, carried out in 2013, of the nearby (z=0.184) luminous (L_bol˜1047 erg s-1) quasar PDS 456 in which the X-ray flux was unusually low. The short term X-ray spectral variability has been interpreted in terms of variable absorption and/or intrinsic continuum changes. In the former scenario, the spectral variability is due to variable covering factors of two regions of partially covering absorbers. We find that these absorbers are characterised by an outflow velocity comparable to that of the highly ionised wind, i.e. ˜ 0.25 c, at the 99.9% (3.26σ) confidence level. This suggests that the partially absorbing clouds may be the denser clumpy part of the inhomogeneous wind. Following an obscuration event we obtained a direct estimate of the size of the X-ray emitting region, to be not larger than 20 R_g in PDS 456.

  14. Short-term vs. long-term heart rate variability in ischemic cardiomyopathy risk stratification

    PubMed Central

    Voss, Andreas; Schroeder, Rico; Vallverdú, Montserrat; Schulz, Steffen; Cygankiewicz, Iwona; Vázquez, Rafael; Bayés de Luna, Antoni; Caminal, Pere

    2013-01-01

    In industrialized countries with aging populations, heart failure affects 0.3–2% of the general population. The investigation of 24 h-ECG recordings revealed the potential of nonlinear indices of heart rate variability (HRV) for enhanced risk stratification in patients with ischemic heart failure (IHF). However, long-term analyses are time-consuming, expensive, and delay the initial diagnosis. The objective of this study was to investigate whether 30 min short-term HRV analysis is sufficient for comparable risk stratification in IHF in comparison to 24 h-HRV analysis. From 256 IHF patients [221 at low risk (IHFLR) and 35 at high risk (IHFHR)] (a) 24 h beat-to-beat time series (b) the first 30 min segment (c) the 30 min most stationary day segment and (d) the 30 min most stationary night segment were investigated. We calculated linear (time and frequency domain) and nonlinear HRV analysis indices. Optimal parameter sets for risk stratification in IHF were determined for 24 h and for each 30 min segment by applying discriminant analysis on significant clinical and non-clinical indices. Long- and short-term HRV indices from frequency domain and particularly from nonlinear dynamics revealed high univariate significances (p < 0.01) discriminating between IHFLR and IHFHR. For multivariate risk stratification, optimal mixed parameter sets consisting of 5 indices (clinical and nonlinear) achieved 80.4% AUC (area under the curve of receiver operating characteristics) from 24 h HRV analysis, 84.3% AUC from first 30 min, 82.2 % AUC from daytime 30 min and 81.7% AUC from nighttime 30 min. The optimal parameter set obtained from the first 30 min showed nearly the same classification power when compared to the optimal 24 h-parameter set. As results from stationary daytime and nighttime, 30 min segments indicate that short-term analyses of 30 min may provide at least a comparable risk stratification power in IHF in comparison to a 24 h analysis period. PMID:24379785

  15. Short-Term Variability and Predictors of Urinary Pentachlorophenol Levels in Ohio Preschool Children

    PubMed Central

    Morgan, Marsha; Jones, Paul; Sobus, Jon

    2015-01-01

    Pentachlorophenol (PCP) is a persistent and ubiquitous environmental contaminant. No published data exist on the temporal variability or important predictors of urinary PCP concentrations in young children. In this further analysis of study data, we have examined the associations between selected sociodemographic or lifestyle factors and urinary PCP concentrations in 115 preschool children over a 48-h period and assessed the 48-hour variability of urinary PCP levels in a subset of 15 children. Monitoring was performed at 115 homes and 16 daycares in Ohio (USA) in 2001. Questionnaires/diaries and spot urine samples were collected from each child. The median urinary PCP level was 0.8 ng/mL (range < 0.2–23.8 ng/mL). The intraclass correlation coefficient for urinary PCP was 0.42, which indicates fairly low reliability for a single sample over a 48-h period. In a multiple regression model, age of home and ln(creatinine levels) were significant predictors and sampling season, time spent outside, and pet ownership were marginally significant predictors of ln(urinary PCP levels), collectively explaining 29% of the variability of PCP in urine. To adequately assess short-term exposures of children to PCP, several spot urine measurements are likely needed as well as information regarding residence age, seasonality, time spent outdoors, and pet ownership. PMID:25594782

  16. Microgravity alters respiratory sinus arrhythmia and short-term heart rate variability in humans

    NASA Technical Reports Server (NTRS)

    Migeotte, P-F; Prisk, G. Kim; Paiva, M.; West, J. B. (Principal Investigator)

    2003-01-01

    We studied heart rate (HR), heart rate variability (HRV), and respiratory sinus arrhythmia (RSA) in four male subjects before, during, and after 16 days of spaceflight. The electrocardiogram and respiration were recorded during two periods of 4 min controlled breathing at 7.5 and 15 breaths/min in standing and supine postures on the ground and in microgravity. Low (LF)- and high (HF)-frequency components of the short-term HRV (< or =3 min) were computed through Fourier spectral analysis of the R-R intervals. Early in microgravity, HR was decreased compared with both standing and supine positions and had returned to the supine value by the end of the flight. In microgravity, overall variability, the LF-to-HF ratio, and RSA amplitude and phase were similar to preflight supine values. Immediately postflight, HR increased by approximately 15% and remained elevated 15 days after landing. LF/HF was increased, suggesting an increased sympathetic control of HR standing. The overall variability and RSA amplitude in supine decreased postflight, suggesting that vagal tone decreased, which coupled with the decrease in RSA phase shift suggests that this was the result of an adaptation of autonomic control of HR to microgravity. In addition, these alterations persisted for at least 15 days after return to normal gravity (1G).

  17. Incidence of climate on common frog breeding: Long-term and short-term changes

    NASA Astrophysics Data System (ADS)

    Neveu, André

    2009-09-01

    In Brittany (northwest France), the climate is showing a trend toward warming. This change is increasingly suspected to have a role in driving amphibian decline, but it is very difficult to determine at what level the climate affects the future of species. Recently, some studies have detected some direct effects on breeding phenology and indirect effects on energy allocation. The present study explores some of these effects on the common frog ( Rana temporaria) from 1984 to 2007. The results show two trends: a long-term change in breeding activities and a short-term influence due to the 2003 climatic anomaly. For the period of study, the start of egg-laying shows a precocity that was correlated with thermal conditions during the preceding 40 days as well as milder springs during the previous year. This degree of precocity is currently the highest found in Europe (+26.6 days). As a result of the 2003 heat wave, the clutch mean fecundity in 2004 was smaller than for other years, the fecundity rates were reduced and abortions were numerous (unlike other years). Moreover, young females were the smallest observed in recent years and some females seemed to exhibit a trade-off between fecundity and growth. Before or after egg-laying, female body condition and mean weight of mature ovules were both lower. The year 2005 appears as a transition period before the recovery in 2006-2007. The results show that climate warming endangers the vital rates of the common frog, while the 2003 climatic events seem more detrimental than the long-term warming trend.

  18. Long and Short Term Variability of the Main Physical Parameters in the Coastal Area of the SE Baltic Proper

    NASA Astrophysics Data System (ADS)

    Mingelaite, Toma; Rukseniene, Viktorija; Dailidiene, Inga

    2015-04-01

    Keywords: SE Baltic Sea, coastal upwelling, IR Remote Sensing The memory of the ocean and seas of atmospheric forcing events contributes to the long-term climate change. Intensifying climate change processes in the North Atlantic region including Baltic Sea has drawn widespread interest, as a changing water temperature has ecological, economic and social impact in coastal areas of the Europe seas. In this work we analyse long and short term variability of the main physical parameters in the coastal area of the South Eastern Baltic Sea Proper. The analysis of long term variability is based on monitoring data measured in the South Eastern Baltic Sea for the last 50 years. The main focus of the long term variability is changes of hydro meteorological parameters relevant to the observed changes in the climate.The water salinity variations in the Baltic Sea near the Lithuanian coast and in the Curonian Lagoon, a shallow and enclosed sub-basin of the Baltic Sea, were analysed along with the time series of some related hydroclimatic factors. The short term water temperature and salinity variations were analysed with a strong focus on coastal upwelling events. Combining both remote sensing and in situ monitoring data physical parameters such as vertical salinity variations during upwelling events was analysed. The coastal upwelling in the SE Baltic Sea coast, depending on its scale and intensity, may lead to an intrusion of colder and saltier marine waters to the Curonian Lagoon resulting in hydrodynamic changes and pronounced temperature drop extending for 30-40 km further down the Lagoon. The study results show that increasing trends of water level, air and water temperature, and decreasing ice cover duration are related to the changes in meso-scale atmospheric circulation, and more specifically, to the changes in regional and local wind regime climate. That is in a good agreement with the increasing trends in local higher intensity of westerly winds, and with the winter

  19. Heavy precipitation in a changing climate: Does short-term summer precipitation increase faster?

    NASA Astrophysics Data System (ADS)

    Ban, Nikolina; Schmidli, Juerg; Schär, Christoph

    2015-04-01

    it is inconsistent to extrapolate from present-day super-adiabatic precipitation scaling into the future. The applicability of the Clausius-Clapeyron scaling across the whole event spectrum is a potentially useful result for climate impact adaptation. Ban, N., J. Schmidli and C. Schär (2015): Heavy precipitation in a changing climate: Does short-term summer precipitation increase faster? Submitted to GRL. Ban, N., J. Schmidli and C. Schär (2014): Evaluation of the convection-resolving regional climate modeling approach in decade-long simulations. J. Geophys. Res. Atmos.,119, 7889-7907, doi:10.1002/2014JD021478

  20. Short-term heart rate variability in older patients with newly diagnosed depression.

    PubMed

    Ha, Jee Hyun; Park, Soyeon; Yoon, Daehyun; Kim, Byungsu

    2015-04-30

    Dysfunction of the autonomic nervous system has been considered to be a risk factor for major depressive disorder (MDD) and cardiovascular disease (CVD). The aim of this study was to evaluate short-term heart rate variability (HRV) in elderly patients with newly diagnosed MDD. Thirty MDD patients over 60 years old newly diagnosed by a structured interview were enrolled, free from antidepressants. Socio-demographic data, blood tests, and heart rate variability (HRV) obtained from 5-min ECG were gathered. The MDD group showed significantly lower very low frequency power, low frequency power, high frequency power, and total power in frequency domain. In time domain analysis, the MDD group showed a significantly smaller standard deviation of the NN, root mean square of the differences of the successive NN, and NN50/total number of all NNs. These findings demonstrated a lower HRV in older patients who were newly diagnosed with depression without a history of CVD and antidepressants effect, compared with the control subjects. Low HRV may be an important predictor of both MDD and CVD in elderly. The use of HRV in elderly depressive patients could be a meaningful screening method for risk of CVD. PMID:25747680

  1. Energy Storage on the Grid and the Short-term Variability of Wind

    NASA Astrophysics Data System (ADS)

    Hittinger, Eric Stephen

    profitability of wind farms. We find that market scenarios using existing price signals to motivate wind to reduce variability allow wind generators to participate in variability reduction when the market conditions are favorable, and can reduce short-term (30-minute) fluctuations while having little effect on wind farm revenue.

  2. Global Ocean Sensitivity to Local Geologically Short-Term Variability of Freshwater Fluxes

    NASA Astrophysics Data System (ADS)

    Seidov, D.; Haupt, B. J.

    2004-12-01

    The geologic record and computer modeling indicate that the transitions between cold and warm climates during the last deglaciation , driven by internal climate dynamics, were geologically very fast, lasting for only decades or shorter. The THC is, perhaps, the only viable candidate for driving these kinds of abrupt changes. Current perception of how the THC may become an agent of abrupt climate change is that the THC is rather sensitive to changes in freshwater fluxes in the high-latitudes, also known as major meltwater events. Our recent numerical experiments challenge the idea of the high-latitudinal meltwater events as the only possible cause of THC alteration. These experiments suggest that the inter-basin sea surface salinity contrasts caused by disparity of freshwater fluxes over the world ocean can also be a very potent factor in THC dynamics. To address the role of changes in both high-latitudinal and inter-basin freshwater fluxes in altering the global THC, we performed several simple numerical experiments. First, we ran the atmospheric control experiment using the NCAR Community Climate Model (CCM) with observed sea surface temperature (SST) and salinity to get the present-day control atmospheric state, that is, the wind stress, SST, and freshwater fluxes across the sea surfaces. Next, we ran the oceanic control experiment using the GFDL Modular Ocean Model (MOM) with these sea surface conditions from the CCM. In the first series of experiments, we specified idealized anomalies of freshwater fluxes in the northern North Atlantic, the Southern Ocean, and the subtropical North Atlantic and North Pacific. These experiments gave us insight on the relative importance of high-latitudinal and inter-basin short-term fluctuations in freshwater balance for the THC dynamics. In the second series of experiments, we simulated the disruption of the freshwater regime in the northern North Atlantic caused by freshwater floods from Lake Agassiz (a glacial lake that

  3. Short Term Variability in Water Column and Porewater Carbon Chemistry on a Tropical Reef

    NASA Astrophysics Data System (ADS)

    Drupp, P. S.; De Carlo, E. H.; Mackenzie, F. T.; Thompson, R.; Sabine, C. L.; Feely, R. A.

    2013-12-01

    A high-resolution carbon system study has been ongoing on the Kaneohe Bay barrier reef on the island of Oahu, Hawaii since 2008, in an effort to characterize short term variability of the carbon system in the water column and porewaters. In addition, during a 3 week time period from June 4th-24th, multiple sensors were deployed at the CRIMP-2 MAPCO2 buoy and discrete bottle samples were collected frequently, including once an hour for a period of 48 hours. In-situ sensors measured pCO2, pH, temperature and salinity at the CRIMP-2 location. Dissolved inorganic carbon to total alkalinity ratios indicate a reef system where primary production slightly exceeds calcification, consistent with previous studies on the reef. A second MAP-CO2 buoy located outside the bay (Kaneohe Buoy) also measured pCO2 and pH to serve as an end member point for water entering the reef system. Porewater has been collected at varying depths in order to determine the effect of overlying water conditions on the carbonic-acid system chemistry. Porewater alkalinity appears to vary with changes in overlying water column chemistry and physical forcings such as wind and current speeds, which influence flushing rates and ventilation, and calcium and magnesium data suggests dissolution of soluble magnesian calcites concurrently with precipitation of calcites.

  4. Validity of the ithlete™ Smart Phone Application for Determining Ultra-Short-Term Heart Rate Variability.

    PubMed

    Flatt, Andrew A; Esco, Michael R

    2013-12-18

    The purpose of this investigation was to cross-validate the ithlete™ heart rate variability smart phone application with an electrocardiograph for determining ultra-short-term root mean square of successive R-R intervals. The root mean square of successive R-R intervals was simultaneously determined via electrocardiograph and ithlete™ at rest in twenty five healthy participants. There were no significant differences between the electrocardiograph and ithlete™ derived root mean square of successive R-R interval values (p > 0.05) and the correlation was near perfect (r = 0.99, p < 0.001). In addition, the ithlete™ revealed a Standard Error of the Estimate of 1.47 and Bland Altman plot showed that the limits of agreement ranged from 2.57 below to 2.63 above the constant error of -0.03. In conclusion, the ithlete™ appeared to provide a suitably accurate measure of root mean square of successive R-R intervals when compared to the electrocardiograph measures obtained in the laboratory within the current sample of healthy adult participants. The current study lays groundwork for future research determining the efficacy of ithlete™ for reflecting athletic training status over a chronic conditioning period. PMID:24511344

  5. Validity of the ithlete™ Smart Phone Application for Determining Ultra-Short-Term Heart Rate Variability

    PubMed Central

    Flatt, Andrew A.; Esco, Michael R.

    2013-01-01

    The purpose of this investigation was to cross-validate the ithlete™ heart rate variability smart phone application with an electrocardiograph for determining ultra-short-term root mean square of successive R-R intervals. The root mean square of successive R-R intervals was simultaneously determined via electrocardiograph and ithlete™ at rest in twenty five healthy participants. There were no significant differences between the electrocardiograph and ithlete™ derived root mean square of successive R-R interval values (p > 0.05) and the correlation was near perfect (r = 0.99, p < 0.001). In addition, the ithlete™ revealed a Standard Error of the Estimate of 1.47 and Bland Altman plot showed that the limits of agreement ranged from 2.57 below to 2.63 above the constant error of −0.03. In conclusion, the ithlete™ appeared to provide a suitably accurate measure of root mean square of successive R-R intervals when compared to the electrocardiograph measures obtained in the laboratory within the current sample of healthy adult participants. The current study lays groundwork for future research determining the efficacy of ithlete™ for reflecting athletic training status over a chronic conditioning period. PMID:24511344

  6. Carbon monoxide short term variability observed on Venus with SOIR/VEX

    NASA Astrophysics Data System (ADS)

    Vandaele, A. C.; Mahieux, A.; Robert, S.; Drummond, R.; Wilquet, V.; Bertaux, J. L.

    2015-08-01

    The SOIR instrument on board the ESA Venus Express mission has been operational since the insertion of the satellite around Venus in 2006. Since then, it has delivered high quality spectra of the atmosphere of Venus. Spectra are recorded in the IR spectral region (2.2-4.3 μm) using the solar occultation geometry and give access to a vast number of ro-vibrational lines and bands of several key species of the atmosphere of Venus. Here we present the retrieval strategy applied to obtain high quality vertical profiles of carbon monoxide (CO) densities and volume mixing ratios (vmr), spanning the 65-150 km altitude range. We discuss the methodology used to derive the profiles and the validation process implemented to ensure the quality and reproducibility of the results. Influence of ancillary data, such as temperature, is discussed. High variability of CO densities and vmr is observed in relatively short term periods. Correlation between CO and CO2 densities, as well as between CO and temperature above 110 km, corroborates that the major process at those altitudes is the photodissociation of CO2 into CO.

  7. Long- and short-term variability of Saturn's ionic radiation belts

    NASA Astrophysics Data System (ADS)

    Roussos, E.; Krupp, N.; Paranicas, C. P.; Kollmann, P.; Mitchell, D. G.; Krimigis, S. M.; Armstrong, T. P.; Went, D. R.; Dougherty, M. K.; Jones, G. H.

    2011-02-01

    Earlier studies of Saturn's inner ionic radiation belts revealed that their content was surprisingly constant while their evolution appeared decoupled from dynamics of the Saturnian magnetosphere. Saturn's icy moons in combination with the neutral gas and dust that surround the planet seem to effectively restrict radial transport of energetic ions and are responsible for all these unusual characteristics. A possible process through which MeV ions may be populating the regions between the icy moons is cosmic ray albedo neutron decay (CRAND). While some circumstantial evidence suggests that this process actually occurs, the concept of CRAND has only been applied to the proton energy spectrum above ˜10 MeV; the source of ions below 10 MeV is not yet obvious. Additional hints about the nature of this source are now becoming evident by monitoring Saturn's radiation belts about half a solar cycle (from the declining phase of the solar maximum to solar minimum). Using Cassini's magnetosphere imaging instrument and low-energy magnetospheric measurement system (MIMI/LEMMS) data from June 2004 to June 2010, we detect a weak intensification of the trapped proton component that probably originates from CRAND (>10 MeV). This anticipated enhancement, due to the solar cycle modulation of the galactic cosmic ray influx at Saturn, is closely followed by ions in the 1-10 MeV range. This observation sets constraints on the nature of those ions' source: this source should be connected (directly or indirectly) to the access of galactic cosmic rays in the Saturnian system. We also find evidence indicating that the ionic belts experience short-term variability following the occurrence of solar energetic particle events at Saturn's distance, probably associated with coronal mass ejections that propagate in the heliosphere. LEMMS data contain clear evidence of Earth-like Forbush decreases following such events. These decreases may explain the lack of an (expected) ionic belt

  8. Discrimination power of short-term heart rate variability measures for CHF assessment.

    PubMed

    Pecchia, Leandro; Melillo, Paolo; Sansone, Mario; Bracale, Marcello

    2011-01-01

    In this study, we investigated the discrimination power of short-term heart rate variability (HRV) for discriminating normal subjects versus chronic heart failure (CHF) patients. We analyzed 1914.40 h of ECG of 83 patients of which 54 are normal and 29 are suffering from CHF with New York Heart Association (NYHA) classification I, II, and III, extracted by public databases. Following guidelines, we performed time and frequency analysis in order to measure HRV features. To assess the discrimination power of HRV features, we designed a classifier based on the classification and regression tree (CART) method, which is a nonparametric statistical technique, strongly effective on nonnormal medical data mining. The best subset of features for subject classification includes square root of the mean of the sum of the squares of differences between adjacent NN intervals (RMSSD), total power, high-frequencies power, and the ratio between low- and high-frequencies power (LF/HF). The classifier we developed achieved sensitivity and specificity values of 79.3 % and 100 %, respectively. Moreover, we demonstrated that it is possible to achieve sensitivity and specificity of 89.7 % and 100 %, respectively, by introducing two nonstandard features ΔAVNN and ΔLF/HF, which account, respectively, for variation over the 24 h of the average of consecutive normal intervals (AVNN) and LF/HF. Our results are comparable with other similar studies, but the method we used is particularly valuable because it allows a fully human-understandable description of classification procedures, in terms of intelligible "if … then …" rules. PMID:21075731

  9. A Meta-Analysis of the Impact of Short-Term Sleep Deprivation on Cognitive Variables

    ERIC Educational Resources Information Center

    Lim, Julian; Dinges, David F.

    2010-01-01

    A substantial amount of research has been conducted in an effort to understand the impact of short-term (less than 48 hr) total sleep deprivation (SD) on outcomes in various cognitive domains. Despite this wealth of information, there has been disagreement on how these data should be interpreted, arising in part because the relative magnitude of…

  10. Multicolor Near-Infrared Intra-Day and Short-Term Variability of the Blazar S5 0716+714

    NASA Astrophysics Data System (ADS)

    Gupta, Alok C.; Cha, Sang-Mok; Lee, Sungho; Jin, Ho; Pak, Soojong; Cho, Seoung-hyun; Moon, Bongkon; Park, Youngsik; Yuk, In-Soo; Nam, Uk-won; Kyeong, Jaemann

    2008-12-01

    In this paper, we report results of our near-infrared (NIR) photometric variability studies of the BL Lacertae (BL Lac) object S5 0716+714. NIR photometric observations were spread over seven nights during our observing run on 2007 April 2-9 at the 1.8 m telescope equipped with the Korea Astronomy and Space Science Institute Near-Infrared Camera System and J, H, and Ks filters at Bohyunsan Optical Astronomy Observatory, South Korea. We searched for intra-day variability (IDV), short-term variability, and color variability in the BL Lac object. We have not detected any genuine IDV in any of the J, H, and Ks passbands in our observing run. Significant short-term variabilities ~32.6%, 20.5% and 18.2% have been detected in the J, H, and Ks passbands, respectively, and ~11.9% in (J - H) color.

  11. Impact of short-term practice of yoga on heart rate variability

    PubMed Central

    Vinay, AV; Venkatesh, D; Ambarish, V

    2016-01-01

    Background: Yoga is a science that facilitates homeostasis, an ancient way of life intended to improve the quality of life of an individual. Practice of yoga is proposed to alter the autonomic nervous system and affect the cardiovascular functioning. This study was intended to assess the influence of short-term practice of yoga for a month on heart rate variability (HRV). Materials and Methods: Totally, 40 healthy male volunteers in the age group of 30–60 years willing to practice yoga for a month were included in the study. HRV was assessed using HRV device (RMS Vagus, India). Preinterventional assessment of HRV was done in these subjects. Practice of yoga that included a set of physical postures (asanas), breathing techniques (pranayama), and meditation (dhyana) were performed for an hour daily for 1 month under the guidance of a certified yoga instructor. Postinterventional assessment of HRV was done. The values were expressed in median and their interquartile range, and statistical analysis was done to compare the changes using Wilcoxon Signed Rank Test. Results: Thirty-two of 40 subjects recruited for yoga practice completed the study protocol. Analysis of HRV revealed that in time domain parameters, SDNN increased from 33.60 (31.41–44.82) to 42.11 (34.43–57.51), RMSSD increased from 22.00 (16.00–33.80) to 25.6 (17.0–34.8), and PNN50 increased from 2.45 (0.80–15.38) to 7.35 (1.40–18.57) after intervention. In the frequency domain parameters, the low-frequency (LF) power spectrum reduced from 39.30 (25.1–46.25) to 30.40 (22.75–40.62) and LF/high-frequency ratio was reduced from 2.62 (1.91–4.07) to 2.28 (1.4–3.07) after 1 month practice of yoga. P < 0.05 was considered statistically significant. Conclusion: Autonomic balance tilts toward parasympathetic predominance after 1 month practice of yoga. PMID:26865773

  12. A Simple Tropical Atmosphere Model of Relevance to Short-Term Climate Variations.

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Li, Tianming

    1993-01-01

    The tropical atmosphere model presented here is suitable for modeling both the annual cycle and short-term (monthly to decadal time scale) climate fluctuations in sole response to the thermal forcing from the underlying surface, especially the ocean surface. The present model consists of a well-mixed planetary boundary layer and a free troposphere represented by the gravest baroclinic mode. The model dynamics involves active interactions between the boundary-layer flow driven by the momentum forcing associated with sea surface temperature (SST) gradient and the free tropospheric flow stimulated by diabatic heating that is controlled by the thermal effects of SST. This process is demonstrated to be essential for modeling Pacific basinwide low-level circulations. The convective heating is parameterized by a SST-dependent conditional heating scheme based upon the proposition that the potential convective instability increases with SST in a nonlinear fashion.The present model integrates the virtue of a Gill-type model with that of a Lindzen-Nigam model and is capable of reproducing both the shallow intertropical convergence zone (ITCZ) in the boundary layer and the deep South Pacific convergence zone (SPCZ) and monsoon troughs in the lower troposphere. The precipitation pattern and intensity, the trade winds and associated subtropical highs, and the near-equatorial trough can also be simulated reasonably well.The thermal contrast between oceans and continents is shown to have a profound influence on the circulation near landmasses. Changes in land surface temperature, however, do not exert significant influence on remote oceanic regions. Both the ITCZ and SPCZ primarily originate from the inhomogeneity of ocean surface thermal conditions. The continents of South and North America contribute to the formation of these oceanic convergence zones through indirect boundary effects that support coastal upwelling changing the SST distribution. The diagnosis of observed surface

  13. Short term response of a peatland to warming and drought - climate manipulation experiment in W Poland

    NASA Astrophysics Data System (ADS)

    Juszczak, Radosław; Chojnicki, Bogdan; Urbaniak, Marek; Leśny, Jacek; Silvennoinen, Hanna; Lamentowicz, Mariusz; Basińska, Anna; Gąbka, Maciej; Stróżecki, Marcin; Samson, Mateusz; Łuców, Dominika; Józefczyk, Damian; Hoffmann, Mathias; Olejnik, Janusz

    2016-04-01

    . Generally, warmer conditions led to increases in NDVI and LAI, whilst the site exposed to only drought exhibited the lowest LAI. Warming shifted the vegetation species composition by promoting vascular plants (mainly Carex rostrata and C. limosa), which result also correlates positively with nutrient (Ptot, Mn, F, Na, Zn) availability in the peat water. Here, we report short-term responses to increased temperature and diminished precipitation, showing that the combination of these to stressors leads to very different scenario than their individual impacts. Our results further emphasize the need for long term records from field manipulation site on peatland response to climate changes. The Research was co-founded by the Polish National Centre for Research and Development within the Polish-Norwegian Research Programme within the WETMAN project (Central European Wetland Ecosystem Feedbacks to Changing Climate - Field Scale Manipulation, Project ID: 203258, contract No. Pol-Nor/203258/31/2013 (www.wetman.pl). References Fenner N., Freeman Ch. (2011). Nature Geoscience, 4, 895-900 Hoffmann M., et al. (2015). Agricultural and Forest Meteorology, 200, 30-45 Kimball BA. (2005). Global Change Biology, 11, 2041-2056

  14. On the dynamic forcing of short-term climate fluctuations by feedback mechanisms

    NASA Technical Reports Server (NTRS)

    Reiter, E. R.

    1979-01-01

    Various internal feedback mechanisms in the ocean atmosphere system were studied. A variability pattern of sea surface temperature with a quasibiennial oscillation (QBO) was detected off the coast of Senegal, in the Gulf of Guinea and even in the Gulf Stream as it leaves the North American continental shelf. Possible physical connections between some of these QBO's were pointed out by a hypothetical feedback model. Interaction of a QBO with the annual cycle may lead to beating frequencies resembling climatic trends of a duration of several years.

  15. NEW CONSTRAINTS ON THE ORIGIN OF THE SHORT-TERM CYCLICAL VARIABILITY OF THE WOLF-RAYET STAR WR 46

    SciTech Connect

    Henault-Brunet, V.; St-Louis, N.; Marchenko, S. V.; Pollock, A. M. T.; Talavera, A.; Carpano, S. E-mail: stlouis@astro.umontreal.ca E-mail: andy.pollock@esa.int E-mail: scarpano@rssd.esa.int

    2011-07-01

    The Wolf-Rayet star WR 46 is known to exhibit a very complex variability pattern on relatively short timescales of a few hours. Periodic but intermittent radial velocity shifts of optical lines as well as multiple photometric periods have been found in the past. Non-radial pulsations, rapid rotational modulation, or the presence of a putative low-mass companion have been proposed to explain the short-term behavior. In an effort to unveil its true nature, we observed WR 46 with the Far Ultraviolet Spectroscopic Explorer (FUSE) over several short-term variability cycles. We found significant variations on a timescale of {approx}8 hr in the far-ultraviolet (FUV) continuum, in the blue edge of the absorption trough of the O VI {lambda}{lambda}1032, 1038 doublet P Cygni profile and in the S VI {lambda}{lambda}933, 944 P Cygni absorption profile. We complemented these observations with X-ray and UV light curves and an X-ray spectrum from archival X-ray Multi-Mirror Mission-Newton Space Telescope (XMM-Newton) data. The X-ray and UV light curves show variations on a timescale similar to the variability found in the FUV. We discuss our results in the context of the different scenarios suggested to explain the short-term variability of this object and reiterate that non-radial pulsations is the scenario most likely to occur.

  16. New Constraints on the Origin of the Short-term Cyclical Variability of the Wolf-Rayet Star WR 46

    NASA Astrophysics Data System (ADS)

    Hénault-Brunet, V.; St-Louis, N.; Marchenko, S. V.; Pollock, A. M. T.; Carpano, S.; Talavera, A.

    2011-07-01

    The Wolf-Rayet star WR 46 is known to exhibit a very complex variability pattern on relatively short timescales of a few hours. Periodic but intermittent radial velocity shifts of optical lines as well as multiple photometric periods have been found in the past. Non-radial pulsations, rapid rotational modulation, or the presence of a putative low-mass companion have been proposed to explain the short-term behavior. In an effort to unveil its true nature, we observed WR 46 with the Far Ultraviolet Spectroscopic Explorer (FUSE) over several short-term variability cycles. We found significant variations on a timescale of ~8 hr in the far-ultraviolet (FUV) continuum, in the blue edge of the absorption trough of the O VI λλ1032, 1038 doublet P Cygni profile and in the S VI λλ933, 944 P Cygni absorption profile. We complemented these observations with X-ray and UV light curves and an X-ray spectrum from archival X-ray Multi-Mirror Mission-Newton Space Telescope (XMM-Newton) data. The X-ray and UV light curves show variations on a timescale similar to the variability found in the FUV. We discuss our results in the context of the different scenarios suggested to explain the short-term variability of this object and reiterate that non-radial pulsations is the scenario most likely to occur.

  17. Short-term blood pressure variability over 24 h and target organ damage in middle-aged men and women.

    PubMed

    Madden, J M; O'Flynn, A M; Dolan, E; Fitzgerald, A P; Kearney, P M

    2015-12-01

    Blood pressure variability (BPV) has been associated with cardiovascular events; however, the prognostic significance of short-term BPV remains uncertain. As uncertainty also remains as to which measure of variability most accurately describes short-term BPV, this study explores different indices and investigates their relationship with subclinical target organ damage (TOD). We used data from the Mitchelstown Study, a cross-sectional study of Irish adults aged 47-73 years (n=2047). A subsample (1207) underwent 24-h ambulatory BP monitoring (ABPM). As measures of short-term BPV, we estimated the s.d., weighted s.d. (wSD), coefficient of variation (CV) and average real variability (ARV). TOD was documented by microalbuminuria and electrocardiogram (ECG) left ventricular hypertrophy (LVH). There was no association found between any measure of BPV and LVH in both unadjusted and fully adjusted logistic regression models. Similar analysis found that ARV (24 h, day and night), s.d. (day and night) and wSD were all univariately associated with microalbuminuria and remained associated after adjustment for age, gender, smoking, body mass index (BMI), diabetes and antihypertensive treatment. However, when the models were further adjusted for the mean BP the association did not persist for all indices. Our findings illustrate choosing the appropriate summary measure, which accurately captures that short-term BPV is difficult. Despite discrepancies in values between the different measures, there was no association between any indexes of variability with TOD measures after adjustment for the mean BP. PMID:25787777

  18. Short-term to seasonal variability in factors driving primary productivity in a shallow estuary: Implications for modeling production

    NASA Astrophysics Data System (ADS)

    Canion, Andy; MacIntyre, Hugh L.; Phipps, Scott

    2013-10-01

    The inputs of primary productivity models may be highly variable on short timescales (hourly to daily) in turbid estuaries, but modeling of productivity in these environments is often implemented with data collected over longer timescales. Daily, seasonal, and spatial variability in primary productivity model parameters: chlorophyll a concentration (Chla), the downwelling light attenuation coefficient (kd), and photosynthesis-irradiance response parameters (Pmchl, αChl) were characterized in Weeks Bay, a nitrogen-impacted shallow estuary in the northern Gulf of Mexico. Variability in primary productivity model parameters in response to environmental forcing, nutrients, and microalgal taxonomic marker pigments were analysed in monthly and short-term datasets. Microalgal biomass (as Chla) was strongly related to total phosphorus concentration on seasonal scales. Hourly data support wind-driven resuspension as a major source of short-term variability in Chla and light attenuation (kd). The empirical relationship between areal primary productivity and a combined variable of biomass and light attenuation showed that variability in the photosynthesis-irradiance response contributed little to the overall variability in primary productivity, and Chla alone could account for 53-86% of the variability in primary productivity. Efforts to model productivity in similar shallow systems with highly variable microalgal biomass may benefit the most by investing resources in improving spatial and temporal resolution of chlorophyll a measurements before increasing the complexity of models used in productivity modeling.

  19. Evaluation of short-term climate change prediction in multi-model CMIP5 decadal hindcasts

    NASA Astrophysics Data System (ADS)

    Kim, Hye-Mi; Webster, Peter J.; Curry, Judith A.

    2012-05-01

    This study assesses the CMIP5 decadal hindcast/forecast simulations of seven state-of-the-art ocean-atmosphere coupled models. Each decadal prediction consists of simulations over a 10 year period each of which are initialized every five years from climate states of 1960/1961 to 2005/2006. Most of the models overestimate trends, whereby the models predict less warming or even cooling in the earlier decades compared to observations and too much warming in recent decades. All models show high prediction skill for surface temperature over the Indian, North Atlantic and western Pacific Oceans where the externally forced component and low-frequency climate variability is dominant. However, low prediction skill is found over the equatorial and North Pacific Ocean. The Atlantic Multidecadal Oscillation (AMO) index is predicted in most of the models with significant skill, while the Pacific Decadal Oscillation (PDO) index shows relatively low predictive skill. The multi-model ensemble has in general better-forecast quality than the single-model systems for global mean surface temperature, AMO and PDO.

  20. [Analysis Methods of Short-term Non-linear Heart Rate Variability and Their Application in Clinical Medicine].

    PubMed

    Chi, Xianglin; Zhou, Jianhua; Shi, Ping; Liu, Chengyu

    2016-02-01

    The linear analysis for heart rate variability (HRV), including time domain method, frequency domain method and time-frequency analysis, has reached a lot of consensus. The non-linear analysis has also been widely applied in biomedical and clinical researches. However, for non-linear HRV analysis, especially for short-term non-linear HRV analysis, controversy still exists, and a unified standard and conclusion has not been formed. This paper reviews and discusses three short-term non-linear HRV analysis methods (fractal dimension, entropy and complexity) and their principles, progresses and problems in clinical application in detail, in order to provide a reference for accurate application in clinical medicine. PMID:27382764

  1. Dynamical downscaling of short-term climate fluctuations: On the benefits of precipitation assimilation

    NASA Astrophysics Data System (ADS)

    Nunes, Ana M. B.; Roads, John O.

    2009-06-01

    Regional downscaling has proven useful in adding details to the global solution. However, the parameterized physical processes can systematically deviate the large-scale features in the regional solution. To demonstrate the precipitation assimilation beneficial impact on the dynamical downscaling, a regional spectral model driven by the National Centers for Environmental Prediction/Department of Energy Atmospheric Model Intercomparison Project II (NCEP/DOE AMIP-II) Reanalysis was used to downscale the large-scale features over most of North America. The North American Regional Reanalysis provided the 3-hourly precipitation rates that the regional model employed to simulate two opposite extreme climate events: the upper Mississippi River Basin 1988 drought and 1993 floods. In addition to these two cases, the 1990 summer anomalous precipitation over the same area was also investigated. Precipitation assimilation positively influences the dynamical downscaling of these extreme climate events. The regional model when assimilating precipitation was particularly successful in reproducing the observed precipitation patterns over the central United States, where the large-scale circulation affects the precipitation variability. Particularly for the flood year, the intensity and location of the subtropical upper-level westerly jet and its associated transverse circulations were noticeably improved in the regional simulations, where the heavy precipitation core was found. This also suggests that the cumulus convection scheme, in this case the Relaxed Arakawa-Schubert parameterization scheme, can cause the large-scale features to drift during the regional simulation, and precipitation assimilation reduces this departure from the global solution. These changes in the upper-level winds were also followed by better characterization of the drought of 1988 as well as the 1990 summer heavy precipitation simulation, in comparison to regional control simulations, where precipitation

  2. Short-term variability of mineral dust, metals and carbon emission from road dust resuspension

    NASA Astrophysics Data System (ADS)

    Amato, Fulvio; Schaap, Martijn; Denier van der Gon, Hugo A. C.; Pandolfi, Marco; Alastuey, Andrés; Keuken, Menno; Querol, Xavier

    2013-08-01

    Particulate matter (PM) pollution in cities has severe impact on morbidity and mortality of their population. In these cities, road dust resuspension contributes largely to PM and airborne heavy metals concentrations. However, the short-term variation of emission through resuspension is not well described in the air quality models, hampering a reliable description of air pollution and related health effects. In this study we experimentally show that the emission strength of resuspension varies widely among road dust components/sources. Our results offer the first experimental evidence of different emission rates for mineral dust, heavy metals and carbon fractions due to traffic-induced resuspension. Also, the same component (or source) recovers differently in a road in Barcelona (Spain) and a road in Utrecht (The Netherlands). This finding has important implications on atmospheric pollution modelling, mostly for mineral dust, heavy metals and carbon species. After rain events, recoveries were generally faster in Barcelona rather than in Utrecht. The largest difference was found for the mineral dust (Al, Si, Ca). Tyre wear particles (organic carbon and zinc) recovered faster than other road dust particles in both cities. The source apportionment of road dust mass provides useful information for air quality management.

  3. Short term X-ray spectral variability of the strong iron-k absorption feature in PDS 456

    NASA Astrophysics Data System (ADS)

    Matzeu, G.; Reeves, J.; Gofford, J.; Nardini, E.; Costa, M.; Braito, V.; O'Brien, P.; Ward, M.; Turner, J.; Miller, L.

    2014-07-01

    We present a recent 500 ks Suzaku and a simultaneous 500 ks XMM-Newton & NuSTAR observations, carried out in 2013, of the nearby (z=0.184) luminous (L_{bol}˜10^{47} erg s^{-1}) quasar PDS 456. Short term X-ray spectral variability, including the presence of a strong and rapidly variable iron-K absorption feature, is observed and subsequently investigated. Here, our attention is focused on the physical interpretation of the short term variability where two models are adopted in the spectral analysis (partial covering vs coronal changes), leading to two valid interpretations. In the partial covering scenario, rapidly varying absorption is due to inhomogeneous dense material and such short timescale changes also entail that that the absorption is due to gas located in the vicinity of the black hole possibly shielding part of the outflow. In the second scenario, the complex spectral variability is due to variations in the intrinsic continuum observed as changes in the soft X-ray spectrum leading subsequent changes in the hard X-ray power-law, possibly induced by Comptonisation in the disc corona. Furthermore it was possible to extrapolate the size and the location of the absorber, its outflowing velocity and a direct estimation of the size of the X-ray emitting region ˜20 R_{g}.

  4. Short-Term Relationship between Hip Fracture and Weather Conditions in Two Spanish Health Areas with Different Climates

    PubMed Central

    Tenías, José María; Estarlich, Marisa; Crespo, Eusebio; Román-Ortiz, Carmen; Arias-Arias, Angel; Ballester, Ferran

    2015-01-01

    Objective. To evaluate differences in the short-term relationship between weather conditions and the incidence of hip fracture in people aged 65 and over among two regions of Spain. Methods. Hip fracture incidence was calculated for the years 2000–2008 for residents of Health Area 14 in Valencian Community (Mediterranean climate) and the “Mancha Centro” Health Area in Castilla-La Mancha (inland climate), Spain. The relationship between hip fracture incidence and weather was analyzed with a case-crossover design and explored in subgroups defined by sex, age, and fracture type. Results. In the inland area, a positive and significant tendency for hip fracture incidence was observed (annual increase: 1.5%) whereas in the Mediterranean area a seasonal increase of 9% was noted in autumn and winter with respect to spring. Weather conditions, especially wind, were significantly associated with hip fracture incidence: days with more frequent windy periods and/or a greater wind velocity were associated with an increase in hip fracture incidence of 51% in the Mediterranean area and 44% in the inland area. Conclusions. Hip fracture incidence exhibits seasonal changes that differ between the Mediterranean and inland areas. The short-term relationship with climate, although similar in both areas, may partly explain these seasonal changes. PMID:25759722

  5. Investigating Inter-Individual Differences in Short-Term Intra-Individual Variability

    ERIC Educational Resources Information Center

    Wang, Lijuan; Hamaker, Ellen; Bergeman, C. S.

    2012-01-01

    Intra-individual variability over a short period of time may contain important information about how individuals differ from each other. In this article we begin by discussing diverse indicators for quantifying intra-individual variability and indicate their advantages and disadvantages. Then we propose an alternative method that models…

  6. Projected climate change impacts and short term predictions on staple crops in Sub-Saharan Africa

    NASA Astrophysics Data System (ADS)

    Mereu, V.; Spano, D.; Gallo, A.; Carboni, G.

    2013-12-01

    Agriculture in Sub-Saharan Africa (SSA) drives the economy of many African countries and it is mainly rain-fed agriculture used for subsistence. Increasing temperatures, changed precipitation patterns and more frequent droughts may lead to a substantial decrease of crop yields. The projected impacts of future climate change on agriculture are expected to be significant and extensive in the SSA due to the shortening of the growing seasons and the increasing of water-stress risk. Differences in Agro-Ecological Zones and geographical characteristics of SSA influence the diverse impacts of climate change, which can greatly differ across the continent and within countries. The vulnerability of African Countries to climate change is aggravated by the low adaptive capacity of the continent, due to the increasing of its population, the widespread poverty, and other social factors. In this contest, the assessment of climate change impact on agricultural sector has a particular interest to stakeholder and policy makers, in order to identify specific agricultural sectors and Agro-Ecological Zones that could be more vulnerable to changes in climatic conditions and to develop the most appropriate policies to cope with these threats. For these reasons, the evaluation of climate change impacts for key crops in SSA was made exploring climate uncertainty and focusing on short period monitoring, which is particularly useful for food security and risk management analysis. The DSSAT-CSM (Decision Support System for Agrotechnology Transfer - Cropping System Model) software, version 4.5 was used for the analysis. Crop simulation models included in DSSAT-CSM are tools that allow to simulate physiological process of crop growth, development and production, by combining genetic crop characteristics and environmental (soil and weather) conditions. For each selected crop, the models were used, after a parameterization phase, to evaluate climate change impacts on crop phenology and production

  7. Short-term variability and predictors of urinary pentachlorophenol levels in Ohio preschool children

    EPA Science Inventory

    Pentachlorophenol (PCP) is a persistent and ubiquitous environmental contaminant. No published data exist on the temporal variability or important predictors of urinary PCP concentrations in young children. In this further analysis of study data, we have examined the associations...

  8. Short term Heart Rate Variability to predict blood pressure drops due to standing: a pilot study

    PubMed Central

    2015-01-01

    Background Standing from a bed or chair may cause a significant lowering of blood pressure (ΔBP), which may have severe consequences such as, for example, falls in older subjects. The goal of this study was to develop a mathematical model to predict the ΔBP due to standing in healthy subjects, based on their Heart Rate Variability, recorded in the 5 minutes before standing. Methods Heart Rate Variability was extracted from an electrocardiogram, recorded from 10 healthy subjects during the 5 minutes before standing. The blood pressure value was measured before and after rising. A mathematical model aiming to predict ΔBP based on Heart Rate Variability measurements was developed using a robust multi-linear regression and was validated with the leave-one-subject-out cross-validation technique. Results The model predicted correctly the ΔBP in 80% of experiments, with an error below the measurement error of sphygmomanometer digital devices (±4.5 mmHg), a false negative rate of 7.5% and a false positive rate of 10%. The magnitude of the ΔBP was associated with a depressed and less chaotic Heart Rate Variability pattern. Conclusions The present study showes that blood pressure lowering due to standing can be predicted by monitoring the Heart Rate Variability in the 5 minutes before standing. PMID:26391336

  9. Effects of Short Term Bioturbation by Common Voles on Biogeochemical Soil Variables

    PubMed Central

    Wilske, Burkhard; Eccard, Jana A.; Zistl-Schlingmann, Marcus; Hohmann, Maximilian; Methler, Annabel; Herde, Antje; Liesenjohann, Thilo; Dannenmann, Michael; Butterbach-Bahl, Klaus; Breuer, Lutz

    2015-01-01

    Bioturbation contributes to soil formation and ecosystem functioning. With respect to the active transport of matter by voles, bioturbation may be considered as a very dynamic process among those shaping soil formation and biogeochemistry. The present study aimed at characterizing and quantifying the effects of bioturbation by voles on soil water relations and carbon and nitrogen stocks. Bioturbation effects were examined based on a field set up in a luvic arenosol comprising of eight 50 × 50 m enclosures with greatly different numbers of common vole (Microtus arvalis L., ca. 35–150 individuals ha–1 mth–1). Eleven key soil variables were analyzed: bulk density, infiltration rate, saturated hydraulic conductivity, water holding capacity, contents of soil organic carbon (SOC) and total nitrogen (N), CO2 emission potential, C/N ratio, the stable isotopic signatures of 13C and 15N, and pH. The highest vole densities were hypothesized to cause significant changes in some variables within 21 months. Results showed that land history had still a major influence, as eight key variables displayed an additional or sole influence of topography. However, the δ15N at depths of 10–20 and 20–30 cm decreased and increased with increasing vole numbers, respectively. Also the CO2 emission potential from soil collected at a depth of 15–30 cm decreased and the C/N ratio at 5–10 cm depth narrowed with increasing vole numbers. These variables indicated the first influence of voles on the respective mineralization processes in some soil layers. Tendencies of vole activity homogenizing SOC and N contents across layers were not significant. The results of the other seven key variables did not confirm significant effects of voles. Thus overall, we found mainly a first response of variables that are indicative for changes in biogeochemical dynamics but not yet of those representing changes in pools. PMID:25954967

  10. Short-term VHE variability in blazars: PKS 2155-304

    NASA Astrophysics Data System (ADS)

    Rieger, F. M.; Volpe, F.

    2010-09-01

    Context. The γ-ray blazar PKS 2155-304 has attracted considerable attention because of its extreme TeV variability characteristics during an exceptional flaring period in 2006. Among the observed key findings are (i) a minimum variability timescale as short as ~200 s and (ii) highly variable TeV emission, which in the frequency interval [ 10-4 Hz, 10-2 Hz] can be described by a log-normal distribution and suggests an underlying multiplicative (and not additive) process. Aims: Simultaneously accounting for these findings appears difficult within conventional approaches. Following earlier suggestions for the TeV blazar Mkn 501, we explore a possible scenario where PKS 2155-304 is supposed to harbor a supermassive binary black hole system and where the observed TeV variability is dominated by emission from the less massive black hole. Methods: We analyze the constraints on the very high energy (VHE) source imposed by the observed variability characteristics and the integrated VHE luminosity output, and discuss its implications for a binary black hole system. Results: We show that for a secondary mass of mBH ~ 107 M⊙, fluctuations in the disk accretion rate that feed the jet could account for the observed red-noise type variability process down to frequencies of ~10-2 Hz. Jet curvature induced by orbital motion, on the other hand, could further relax constraints on the intrinsic jet speeds. Conclusions: Because a binary system can lead to different (yet not independent) periodicities in different energy bands, a longterm (quasi-) periodicity analysis could offer important insights into the real nature of the central engine of PKS 2155-304.

  11. Simulating small-scale climate change effects-lessons from a short-term field manipulation experiment on grassland arthropods.

    PubMed

    Buchholz, Sascha; Rolfsmeyer, Dorothee; Schirmel, Jens

    2013-10-01

    Climate change is expected to cause major consequences on biodiversity. Understanding species-specific reactions, such as species shifts, species declines, and changes in population dynamics is a key issue to quantify large-scale impacts of climate change on biotic communities. As it is often impossible or at least impracticable to conduct large-scale experiments on biotic responses to climate change, studies at a smaller scale may be a useful alternative. In our study, we therefore tested responses of grassland arthropods (carabid beetles, spiders, grasshoppers) to simulated climate change in terms of species activity densities and diversity. We conducted a controlled field experiment by changing water and microclimatic conditions at a small scale (16 m(2) ). Roof constructions were used to increase drought-like conditions, whereas water supply was enhanced by irrigation. In all, 2 038 carabid beetles (36 species), 4 893 spiders (65 species), and 303 Orthoptera (4 species) were caught using pitfall traps from May to August, 2010. During our experiment, we created an artificial small-scale climate change; and statistics revealed that these changes had short-term effects on the total number of individuals and Simpson diversity of the studied arthropod groups. Moreover, our results showed that certain species might react very quickly to climate change in terms of activity densities, which in turn might influence diversity due to shifts in abundance patterns. Finally, we devised methodological improvements that may further enhance the validity of future studies. PMID:23956202

  12. A New Approach to Detect Congestive Heart Failure Using Short-Term Heart Rate Variability Measures

    PubMed Central

    Wang, Qian; Zhou, GuangMin; Wang, Ying; Jiang, Qing

    2014-01-01

    Heart rate variability (HRV) analysis has quantified the functioning of the autonomic regulation of the heart and heart's ability to respond. However, majority of studies on HRV report several differences between patients with congestive heart failure (CHF) and healthy subjects, such as time-domain, frequency domain and nonlinear HRV measures. In the paper, we mainly presented a new approach to detect congestive heart failure (CHF) based on combination support vector machine (SVM) and three nonstandard heart rate variability (HRV) measures (e.g. SUM_TD, SUM_FD and SUM_IE). The CHF classification model was presented by using SVM classifier with the combination SUM_TD and SUM_FD. In the analysis performed, we found that the CHF classification algorithm could obtain the best performance with the CHF classification accuracy, sensitivity and specificity of 100%, 100%, 100%, respectively. PMID:24747432

  13. Short term and multi-band variability of the active nucleus of IC310

    NASA Astrophysics Data System (ADS)

    Eisenacher, Dorit; Colin, Pierre; Lombardi, Saverio; Sitarek, Julian; Zandanel, Fabio; MAGIC Collaboration; Paneque, David; Fermi-LAT Collaboration; Dauser, Thomas; Krauß, Felicia; Wilbert, Sven; Kadler, Matthias; Schulz, Robert; Wilms, Joern; Bach, Uwe; Ros, Eduardo

    2012-12-01

    The MAGIC Telescopes detected the active galaxy IC 310 at very high energies (VHE, >100 GeV) during observations of the Perseus cluster in 2009 and 2010. This source had originally been classified as a head-tail radio galaxy. By contrast, recent high-resolution radio images obtained with the VLBA reveal the blazar-like structure of IC 310 on parsec scales. This object is also investigated in terms of its variability at X-ray and gamma-ray energies. Studies of the multi-band flux variability at different time periods are presented. The spectral evolution seems to be different in the VHE gamma-ray and X-ray bands.

  14. Investigating inter-individual differences in short-term intra-individual variability

    PubMed Central

    Wang, Lijuan (Peggy); Hamaker, Ellen; Bergeman, C. S.

    2012-01-01

    Intra-individual variability over a short period of time may contain important information about how individuals differ from each other. In this paper we begin by discussing diverse indicators for quantifying intra-individual variability and indicate their advantages and disadvantages. Then we propose an alternative method that models inter-individual differences in intra-individual variability by separately considering both the amplitude of fluctuations and temporal dependency in the data. In the proposed model, temporal dependency and amplitude of fluctuations are both included as random effects. Parameter estimation is done with a multiple-step approach using maximum likelihood, or with a recommended one-step approach using a Bayesian method. The similarity and differences between the proposed method and some existing methods are discussed and investigated using diary study data from older adults. The results from empirical data analysis revealed that temporal dependency and amplitude of fluctuations have different predictability of health outcomes and thus should be modeled and considered separately. PMID:22924600

  15. Soil Microbial Community Responses to Short-term Multiple Experimental Climate Change Drivers

    NASA Astrophysics Data System (ADS)

    Li, Guanlin; Lee, Jongyeol; Lee, Sohye; Roh, Yujin; Son, Yowhan

    2016-04-01

    It is agreed that soil microbial communities are responsible for the cycling of carbon and nutrients in ecosystems; however, the response of these microbial communities to climate change has not been clearly understood. In this study, we measured the direct and interactive effects of climate change drivers on soil bacterial and fungal communities (abundance and composition) in an open-field multifactor climate change experiment. The experimental treatment system was established with two-year-old Pinus densiflora seedlings at Korea University in April 2013, and consisted of six different treatments with three replicates: two levels of air temperature warming (control and +3° C) were crossed with three levels of precipitation manipulation (control, -30% and +30%). After 2.5 years of treatments, in August, 2015, soil samples were collected from the topsoil (0-15cm) of all plots (n=18). High-throughput sequencing technology was used to assess the abundance and composition of soil bacterial and fungal community. Analysis of variance for a blocked split-plot design was used to detect the effects of climate change drivers and their interaction on the abundance and composition of soil bacterial and fungal community. Our results showed that 1) only the significant effect of warming on fungal community abundance was observed (P <0.05); 2) on average, warming decreased both bacterial and fungal community abundance by 20.90% and 32.30%, 6.69% and 45.89%, 14.71% and 19.56% in control, decreased, and increased precipitation plots, respectively; 3) however, warming increased the relative bacterium/fungus ratio on average by 14.03%, 37.03% and 14.31% in control, decreased, and increased precipitation plots, respectively; 4) the phylogenetic distribution of bacterial and fungal groups and their relative abundance varied among treatments; 5) treatments altered the relative abundance of Ascomycota and Basidiomycota, where Ascomycota decreased with a concomitant increase in the

  16. Numerical experiments on short-term meteorological effects on solar variability

    NASA Technical Reports Server (NTRS)

    Somerville, R. C. J.; Hansen, J. E.; Stone, P. H.; Quirk, W. J.; Lacis, A. A.

    1975-01-01

    A set of numerical experiments was conducted to test the short-range sensitivity of a large atmospheric general circulation model to changes in solar constant and ozone amount. On the basis of the results of 12-day sets of integrations with very large variations in these parameters, it is concluded that realistic variations would produce insignificant meteorological effects. Any causal relationships between solar variability and weather, for time scales of two weeks or less, rely upon changes in parameters other than solar constant or ozone amounts, or upon mechanisms not yet incorporated in the model.

  17. Making short-term climate forecasts useful: Linking science and action

    PubMed Central

    Buizer, James; Jacobs, Katharine; Cash, David

    2016-01-01

    This paper discusses the evolution of scientific and social understanding that has led to the development of knowledge systems supporting the application of El Niño-Southern Oscillation (ENSO) forecasts, including the development of successful efforts to connect climate predictions with sectoral applications and actions “on the ground”. The evolution of “boundary-spanning” activities to connect science and decisionmaking is then discussed, setting the stage for a report of outcomes from an international workshop comprised of producers, translators, and users of climate predictions. The workshop, which focused on identifying critical boundary-spanning features of successful boundary organizations, included participants from Australia, Hawaii, and the Pacific Islands, the US Pacific Northwest, and the state of Ceará in northwestern Brazil. Workshop participants agreed that boundary organizations have multiple roles including those of information broker, convenor of forums for engagement, translator of scientific information, arbiter of access to knowledge, and exemplar of adaptive behavior. Through these roles, boundary organizations will ensure the stability of the knowledge system in a changing political, economic, and climatic context. The international examples reviewed in this workshop demonstrated an interesting case of convergent evolution, where organizations that were very different in origin evolved toward similar structures and individuals engaged in them had similar experiences to share. These examples provide evidence that boundary organizations and boundary-spanners fill some social/institutional roles that are independent of culture. PMID:20133668

  18. Making short-term climate forecasts useful: Linking science and action.

    PubMed

    Buizer, James; Jacobs, Katharine; Cash, David

    2016-04-26

    This paper discusses the evolution of scientific and social understanding that has led to the development of knowledge systems supporting the application of El Niño-Southern Oscillation (ENSO) forecasts, including the development of successful efforts to connect climate predictions with sectoral applications and actions "on the ground". The evolution of "boundary-spanning" activities to connect science and decisionmaking is then discussed, setting the stage for a report of outcomes from an international workshop comprised of producers, translators, and users of climate predictions. The workshop, which focused on identifying critical boundary-spanning features of successful boundary organizations, included participants from Australia, Hawaii, and the Pacific Islands, the US Pacific Northwest, and the state of Ceará in northwestern Brazil. Workshop participants agreed that boundary organizations have multiple roles including those of information broker, convenor of forums for engagement, translator of scientific information, arbiter of access to knowledge, and exemplar of adaptive behavior. Through these roles, boundary organizations will ensure the stability of the knowledge system in a changing political, economic, and climatic context. The international examples reviewed in this workshop demonstrated an interesting case of convergent evolution, where organizations that were very different in origin evolved toward similar structures and individuals engaged in them had similar experiences to share. These examples provide evidence that boundary organizations and boundary-spanners fill some social/institutional roles that are independent of culture. PMID:20133668

  19. Short-term meso-scale variability of mesozooplankton communities in a coastal upwelling system (NW Spain)

    NASA Astrophysics Data System (ADS)

    Roura, Álvaro; Álvarez-Salgado, Xosé A.; González, Ángel F.; Gregori, María; Rosón, Gabriel; Guerra, Ángel

    2013-02-01

    The short-term, meso-scale variability of the mesozooplankton community present in the coastal upwelling system of the Ría de Vigo (NW Spain) has been analysed. Three well-defined communities were identified: coastal, frontal and oceanic, according to their holoplankton-meroplankton ratio, richness, and total abundance. These communities changed from summer to autumn due to a shift from downwelling to upwelling-favourable conditions coupled with taxa dependent changes in life strategies. Relationships between the resemblance matrix of mesozooplankton and the resemblance matrices of meteorologic, hydrographic and community-derived biotic variables were determined with distance-based linear models (DistLM, 18 variables), showing an increasing amount of explained variability of 6%, 16.1% and 54.5%, respectively. A simplified model revealed that the variability found in the resemblance matrix of mesozooplankton was mainly described by the holoplankton-meroplankton ratio, the total abundance, the influence of lunar cycles, the upwelling index and the richness; altogether accounting for 64% of the total variability. The largest variability of the mesozooplankton resemblance matrix (39.6%) is accounted by the holoplankton-meroplankton ratio, a simple index that describes appropriately the coastal-ocean gradient. The communities described herein kept their integrity in the studied upwelling and downwelling episodes in spite of the highly advective environment off the Ría de Vigo, presumably due to behavioural changes in the vertical position of the zooplankton.

  20. Beyond hydrography: daily ichthyoplankton variability and short term oceanographic events on the Sydney continental shelf

    NASA Astrophysics Data System (ADS)

    Dempster, Tim; Gibbs, Mark T.; Rissik, David; Suthers, Iain M.

    1997-10-01

    Surface ichthyoplankton concentrations along a shore-normal transect across the Sydney continental shelf and upper slope changed between three replicate nights in January and April of 1994. Over 70 families of fish were recorded, which, during January, included: Myctophidae (49% of individuals), Carangidae (14%), Gonostomatidae (11%) and Pomacentridae (8%); and during April included: Gonorhynchidae (43%), Myctophidae (10%), Berycidae (11%) and Serranidae (6%). Multidimensional scaling analysis identified inshore and offshore communities, which nightly moved between the nearshore and mid-shelf stations. During January no distinct near-surface water masses could be identified from the temperature-salinity data, although the shelf waters were under the influence of forcing by the local wind stress and the East Australian Current. Good agreement between the cross-shore transport in the near-surface layer and the temporal variability of the icthyoplankton was nevertheless found. The sampling during April was performed during a period of relatively steady oceanographic conditions, and two water masses were identified from the hydrographic data. Temporal ichthyoplankton variability at any station was correspondingly less during the April period and stable inshore and offshore communities were identified, that shifted with characteristic water masses. The results presented in this paper demonstrate that the large variance often associated with ichthyoplankton distribution within a similar water mass may be interpreted by the dynamics in cross-shelf flows, which has implications for the selection of control sites used when studying environmental impacts of coastal outfalls.

  1. Short-term Variability in the Moist Static Energy Budget Inferred from Satellite Observations

    NASA Astrophysics Data System (ADS)

    Masunaga, H.; L'Ecuyer, T. S.

    2013-12-01

    The thermodynamic variability of tropical atmosphere associated with the development of moist convection is investigated using satellite measurements from a range of platforms and instruments. Based on the analysis strategy devised by Masunaga (2013), the hourly to daily scale variability of moisture and moist static energy (MSE) convergences are derived from a coordination of TRMM, A-Train, and QuikSCAT sensors. Normalized gross moist stability (GMS; Neelin and Held 1987, Raymond et al. 2007) is then estimated as a measure of large-scale dynamics involving moist convection. GMS is found to decline toward zero before convection and gradually increase back to a positive value as the convection decays. To understand the observed behavior of GMS, large-scale vertical motion is derived from the observational constraint on moisture and thermal budget. The main results include: 1) the negative second baroclinic mode (congestus mode) enhances before convection, which is responsible for the initial reduction of GMS, 2) the rapid development of the first baroclinic mode (deep convection mode) follows and yields heavy precipitation, and 3) the second baroclinic mode switches its sign to positive (strartiform mode), resulting in the restoration of GMS, as deep convection diminishes.

  2. Improved short-term variability in the thermosphere-ionosphere-mesosphere-electrodynamics general circulation model

    NASA Astrophysics Data System (ADS)

    Häusler, K.; Hagan, M. E.; Baumgaertner, A. J. G.; Maute, A.; Lu, G.; Doornbos, E.; Bruinsma, S.; Forbes, J. M.; Gasperini, F.

    2014-08-01

    We report on a new source of tidal variability in the National Center for Atmospheric Research thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM). Lower boundary forcing of the TIME-GCM for a simulation of November-December 2009 based on 3-hourly Modern-Era Retrospective Analysis for Research and Application (MERRA) reanalysis data includes day-to-day variations in both diurnal and semidiurnal tides of tropospheric origin. Comparison with TIME-GCM results from a heretofore standard simulation that includes climatological tropospheric tides from the global-scale wave model reveal evidence of the impacts of MERRA forcing throughout the model domain, including measurable tidal variability in the TIME-GCM upper thermosphere. Additional comparisons with measurements made by the Gravity field and steady-state Ocean Circulation Explorer satellite show improved TIME-GCM capability to capture day-to-day variations in thermospheric density for the November-December 2009 period with the new MERRA lower boundary forcing.

  3. Anatomy of the AGN in NGC 5548. IV. The short-term variability of the outflows

    NASA Astrophysics Data System (ADS)

    Di Gesu, L.; Costantini, E.; Ebrero, J.; Mehdipour, M.; Kaastra, J. S.; Ursini, F.; Petrucci, P. O.; Cappi, M.; Kriss, G. A.; Bianchi, S.; Branduardi-Raymont, G.; De Marco, B.; De Rosa, A.; Kaspi, S.; Paltani, S.; Pinto, C.; Ponti, G.; Steenbrugge, K. C.; Whewell, M.

    2015-07-01

    During an extensive multiwavelength campaign that we performed in 2013-2014, we found the prototypical Seyfert 1 galaxy NGC 5548 in an unusual condition of heavy and persistent obscuration. The newly discovered "obscurer" absorbs most of the soft X-ray continuum along our line of sight and lowers the ionizing luminosity received by the classical warm absorber. We present the analysis of the high resolution X-ray spectra collected with XMM-Newton and Chandra throughout the campaign, which are suitable to investigate the variability of both the obscurer and classical warm absorber. The time separation between these X-ray observations range from two days to eight months. On these timescales the obscurer is variable both in column density and in covering fraction. This is consistent with the picture of a patchy wind. The most significant variation occurred in September 2013 when the source brightened for two weeks. A higher and steeper intrinsic continuum and a lower obscurer covering fraction are both required to explain the spectral shape during the flare. We suggest that a geometrical change of the soft X-ray source behind the obscurer causes the observed drop in the covering fraction. Because of the higher soft X-ray continuum level, the September 2013 Chandra spectrum is the only X ray spectrum of the campaign in which individual features of the warm absorber could be detected. The spectrum shows absorption from Fe-UTA, O iv, and O v, consistent with belonging to the lower-ionization counterpart of the historical NGC 5548 warm absorber. Hence, we confirm that the warm absorber has responded to the drop in the ionizing luminosity caused by the obscurer.

  4. On spatiotemporal series analysis and its application to predict the regional short term climate process

    NASA Astrophysics Data System (ADS)

    Wang, Geli; Yang, Peicai; Lü, Daren

    2004-04-01

    Based on the theory of reconstructing state space, a technique for spatiotemporal series prediction is presented. By means of this technique and NCEP/NCAR data of the monthly mean geopotential height anomaly of the 500-hPa isobaric surface in the Northern Hemisphere, a regional prediction experiment is also carried out. If using the correlation coefficient R between the observed field and the prediction field to measure the prediction accuracy, the averaged R given by 48 prediction samples reaches 21%, which corresponds to the current prediction level for the short range climate process.

  5. A Study of Short-term White Dwarf Variability Using gPhoton

    NASA Astrophysics Data System (ADS)

    Tucker, Michael; Fleming, Scott W.; Caton, Daniel B.; Million, Chase; Shiao, Bernie

    2016-01-01

    The Galaxy Evolution Explorer (GALEX) was a UV space telescope that operated from 2003 until 2013. A new project at MAST, gPhoton takes advantage of the microchannel-plate photon detector aboard GALEX, which catalogued and time-stamped every photon event by putting the one trillion photon events into a database. Utilizing associated open-source software, gPhoton can create coadd images, movies and light curves at user-defined spatial and temporal scales. As part of early science investigations with gPhoton, 364 white dwarf stars from the McCook-Sion catalog with ample GALEX coverage were photometrically inspected for inter-visit variations during an REU program at STScI. Out of the 364 white dwarfs that were studied, three previously documented pulsating white dwarf stars were confirmed in the UV and (at least) three new pulsating white dwarf stars were discovered. Follow-up observations are conducted at Appalachian State University using optical telescopes at the Dark Sky Observatory. We compare optical and UV light curves of these new white dwarf pulsators and show a selection of other variables found with gPhoton.

  6. Short term variability of aerosol optical thickness at Belsk for the period 2002-2010

    NASA Astrophysics Data System (ADS)

    Pietruczuk, Aleksander

    2013-11-01

    In this work variability of aerosol optical thickness (AOT) measured at Belsk, Poland is studied as well as modification of AOT during airmass advection towards Belsk. AOT measurements taken at Belsk and at AERONET stations located in eastern Germany, Belarus and Scandinavia are used as well as satellite measurements of AOT taken by MODIS instrument onboard Terra and Aqua satellites. Directions of airmass advection are determined by means of cluster analysis of airmass backward-trajectories. Changes of AOT at Belsk from day to day varies around zero regardless of time lag between measurements. The standard deviation of these measurements increases with increasing time lag. In case of advection from west and north direction such standard deviation is reduced. It gives good perspective for a persistent forecast of next day AOT. Analysis of AOT changes during airmass advection toward Belsk reveals two modes of AOT changes distributions. One of them with small increase of AOT and second one with larger increase of AOT, so-called loading mode. Loading mode dominates in case of advection from south direction whilst the first mode of AOT changes dominates in case of advection from other directions. Mean increase of AOT associated with the first mode is 0.034 ± 0.003. Analysis of backward-trajectories shows that aerosol loading occurs over urban/industrial regions located south and south-west of Belsk. Substantial aerosol loading is found during seasonal biomass burning episodes in Eastern Europe.

  7. Novel spectrophotometer for the investigation of short term variability in stellar spectra.

    PubMed

    Stiff, T; Jeffers, S

    1978-06-01

    A variety of astronomical objects (e.g., O(f) stars, B(e) stars, optical counterparts of X-ray sources, etc.) exhibit emission line spectra. For some of these objects the emission line strengths are suspected as being variable (and possibly periodic) over time scales as short as minutes or less. A spectrophotometer has been built whose output signal is a measure of the line strength only. The spectrophotometer is used to look at the emission feature and the adjacent continuum in rapid succession by means of magnetic modulation of the electron image of the optical spectrum in an image tube, thus generating a modulated signal which is detected with a lockin amplifier. This detection technique essentially subtracts off an instrumental dark current signal due to sky background and the signal due to the continuum of the star giving a real time measure of the line strength only. The design of the instrument, its laboratory calibration, and some preliminary observational data are presented. PMID:20198073

  8. Modelling short-term variability in carbon and water exchange in a temperate Scots pine forest

    NASA Astrophysics Data System (ADS)

    Vermeulen, M. H.; Kruijt, B. J.; Hickler, T.; Kabat, P.

    2015-07-01

    The vegetation-atmosphere carbon and water exchange at one particular site can strongly vary from year to year, and understanding this interannual variability in carbon and water exchange (IAVcw) is a critical factor in projecting future ecosystem changes. However, the mechanisms driving this IAVcw are not well understood. We used data on carbon and water fluxes from a multi-year eddy covariance study (1997-2009) in a Dutch Scots pine forest and forced a process-based ecosystem model (Lund-Potsdam-Jena General Ecosystem Simulator; LPJ-GUESS) with local data to, firstly, test whether the model can explain IAVcw and seasonal carbon and water exchange from direct environmental factors only. Initial model runs showed low correlations with estimated annual gross primary productivity (GPP) and annual actual evapotranspiration (AET), while monthly and daily fluxes showed high correlations. The model underestimated GPP and AET during winter and drought events. Secondly, we adapted the temperature inhibition function of photosynthesis to account for the observation that at this particular site, trees continue to assimilate at very low atmospheric temperatures (up to daily averages of -10 °C), resulting in a net carbon sink in winter. While we were able to improve daily and monthly simulations during winter by lowering the modelled minimum temperature threshold for photosynthesis, this did not increase explained IAVcw at the site. Thirdly, we implemented three alternative hypotheses concerning water uptake by plants in order to test which one best corresponds with the data. In particular, we analyse the effects during the 2003 heatwave. These simulations revealed a strong sensitivity of the modelled fluxes during dry and warm conditions, but no single formulation was consistently superior in reproducing the data for all timescales and the overall model-data match for IAVcw could not be improved. Most probably access to deep soil water leads to higher AET and GPP simulated

  9. Modelling short-term variability in carbon and water exchange in a temperate Scots pine forest

    NASA Astrophysics Data System (ADS)

    Vermeulen, M. H.; Kruijt, B. J.; Hickler, T.; Kabat, P.

    2015-02-01

    Vegetation - atmosphere carbon and water exchange at one particular site can strongly vary from year to year, and understanding this interannual variability in carbon and water exchange (IAVcw) is a critical factor in projecting future ecosystem changes. However, the mechanisms driving this IAVcw are not well understood. We used data on carbon and water fluxes from a multi-year Eddy Covariance study (1997-2009) in a Dutch Scots pine forest and forced a process-based ecosystem model (LPJ-GUESS) with local data to, firstly, test whether the model can explain IAVcw and seasonal carbon and water exchange from direct environmental factors only. Initial model runs showed low correlations with estimated annual gross primary productivity (GPP) and annual actual evapotranspiration (AET), while monthly and daily fluxes showed high correlations. The model underestimated GPP and AET during winter and drought events. Secondly, we adapted the temperature inhibition function of photosynthesis to account for the observation that at this particular site, trees continue to assimilate at very low atmospheric temperatures (up to daily averages of -10 °C), resulting in a net carbon sink in winter. While we were able to improve daily and monthly simulations during winter by lowering the modelled minimum temperature threshold for photosynthesis, this did not increase explained IAVcw at the site. Thirdly, we implemented three alternative hypotheses concerning water uptake by plants in order to test which one best corresponds with the data. In particular, we analyse the effects during the 2003 heatwave. These simulations revealed a strong sensitivity of the modelled fluxes during dry and warm conditions, but no single formulation was consistently superior in reproducing the data for all time scales and the overall model-data match for IAVcw could not be improved. Most probably access to deep soil water leads to higher AET and GPP simulated during the heat wave of 2003. We conclude that

  10. Measurement of the effect of Isha Yoga on cardiac autonomic nervous system using short-term heart rate variability

    PubMed Central

    Muralikrishnan, Krishnan; Balakrishnan, Bhavani; Balasubramanian, Kabali; Visnegarawla, Fehmida

    2012-01-01

    Background: Beneficial effects of Yoga have been postulated to be due to modulation of the autonomic nervous system. Objective: To assess the effect of Isha Yoga practices on cardiovascular autonomic nervous system through short-term heart rate variability (HRV). Design of the Study: Short-term HRV of long-term regular healthy 14 (12 males and 2 females) Isha Yoga practitioners was compared with that of age- and gender-matched 14 (12 males and 2 females) non-Yoga practitioners. Methods and Materials: ECG Lead II and respiratory movements were recorded in both groups using Polyrite during supine rest for 5 min and controlled deep breathing for 1 minute. Frequency domain analysis [RR interval is the mean of distance between subsequent R wave peaks in ECG], low frequency (LF) power, high frequency (HF) power, LF normalized units (nu), HF nu, LF/HF ratio] and time domain analysis [Standard Deviation of normal to normal interval (SDNN), square of mean squared difference of successive normal to normal intervals (RMSSD), normal to normal intervals which are differing by 50 ms (NN50), and percentage of NN50 (pNN50)] of HRV variables were analyzed for supine rest. Time domain analysis was recorded for deep breathing. Results: Results showed statistically significant differences between Isha Yoga practitioners and controls in both frequency and time domain analyses of HRV indices, with no difference in resting heart rate between the groups. Conclusions: Practitioners of Isha Yoga showed well-balanced beneficial activity of vagal efferents, an overall increased HRV, and sympathovagal balance, compared to non-Yoga practitioners during supine rest and deep breathing. PMID:22707866

  11. Short-Term Test Results. Transitional Housing Energy Efficiency Retrofit in the Hot Humid Climate

    SciTech Connect

    Sutherland, K.

    2013-02-01

    This project evaluates the renovation of a 5,800 ft2, multi-use facility located in St. Petersburg, on the west coast of central Florida, in the hot humid climate. An optimal package of retrofit measures was designed to deliver 30%-40% annual energy cost savings for this building with annual utility bills exceeding $16,000 and high base load consumption. Researchers projected energy cost savings for potential retrofit measures based on pre-retrofit findings and disaggregated, weather normalized utility bills as a basis for simulation true-up. A cost-benefit analysis was conducted for the seven retrofit measures implemented; adding attic insulation and sealing soffits, tinting windows, improving whole building air-tightness, upgrading heating and cooling systems and retrofitting the air distribution system, replacing water heating systems, retrofitting lighting, and replacing laundry equipment. The projected energy cost savings for the full retrofit package based on a post-retrofit audit is 35%. The building's architectural characteristics, vintage, and residential and commercial uses presented challenges for both economic projections and retrofit measure construction.

  12. Short-Term Test Results: Transitional Housing Energy Efficiency Retrofit in the Hot-Humid Climate

    SciTech Connect

    Sutherland, K.; Martin, E.

    2013-02-01

    This project evaluates the renovation of a 5,800 ft2, multi-use facility located in St. Petersburg, on the west coast of central Florida, in the hot humid climate. An optimal package of retrofit measures was designed to deliver 30-40% annual energy cost savings for this building with annual utility bills exceeding $16,000 and high base load consumption. Researchers projected energy cost savings for potential retrofit measures based on pre-retrofit findings and disaggregated, weather normalized utility bills as a basis for simulation true-up. A cost-benefit analysis was conducted for the seven retrofit measures implemented; adding attic insulation and sealing soffits, tinting windows, improving whole building air-tightness, upgrading heating and cooling systems and retrofitting the air distribution system, replacing water heating systems, retrofitting lighting, and replacing laundry equipment. The projected energy cost savings for the full retrofit package based on a post-retrofit audit is 35%. The building's architectural characteristics, vintage, and residential and commercial uses presented challenges for both economic projections and retrofit measure construction.

  13. Facing the Future: Effects of Short-Term Climate Extremes on Isoprene-Emitting and Nonemitting Poplar.

    PubMed

    Vanzo, Elisa; Jud, Werner; Li, Ziru; Albert, Andreas; Domagalska, Malgorzata A; Ghirardo, Andrea; Niederbacher, Bishu; Frenzel, Juliane; Beemster, Gerrit T S; Asard, Han; Rennenberg, Heinz; Sharkey, Thomas D; Hansel, Armin; Schnitzler, Jörg-Peter

    2015-09-01

    Isoprene emissions from poplar (Populus spp.) plantations can influence atmospheric chemistry and regional climate. These emissions respond strongly to temperature, [CO2], and drought, but the superimposed effect of these three climate change factors are, for the most part, unknown. Performing predicted climate change scenario simulations (periodic and chronic heat and drought spells [HDSs] applied under elevated [CO2]), we analyzed volatile organic compound emissions, photosynthetic performance, leaf growth, and overall carbon (C) gain of poplar genotypes emitting (IE) and nonemitting (NE) isoprene. We aimed (1) to evaluate the proposed beneficial effect of isoprene emission on plant stress mitigation and recovery capacity and (2) to estimate the cumulative net C gain under the projected future climate. During HDSs, the chloroplastidic electron transport rate of NE plants became impaired, while IE plants maintained high values similar to unstressed controls. During recovery from HDS episodes, IE plants reached higher daily net CO2 assimilation rates compared with NE genotypes. Irrespective of the genotype, plants undergoing chronic HDSs showed the lowest cumulative C gain. Under control conditions simulating ambient [CO2], the C gain was lower in the IE plants than in the NE plants. In summary, the data on the overall C gain and plant growth suggest that the beneficial function of isoprene emission in poplar might be of minor importance to mitigate predicted short-term climate extremes under elevated [CO2]. Moreover, we demonstrate that an analysis of the canopy-scale dynamics of isoprene emission and photosynthetic performance under multiple stresses is essential to understand the overall performance under proposed future conditions. PMID:26162427

  14. Facing the Future: Effects of Short-Term Climate Extremes on Isoprene-Emitting and Nonemitting Poplar1

    PubMed Central

    Vanzo, Elisa; Jud, Werner; Li, Ziru; Albert, Andreas; Domagalska, Malgorzata A.; Ghirardo, Andrea; Niederbacher, Bishu; Frenzel, Juliane; Beemster, Gerrit T.S.; Asard, Han; Rennenberg, Heinz; Sharkey, Thomas D.; Hansel, Armin; Schnitzler, Jörg-Peter

    2015-01-01

    Isoprene emissions from poplar (Populus spp.) plantations can influence atmospheric chemistry and regional climate. These emissions respond strongly to temperature, [CO2], and drought, but the superimposed effect of these three climate change factors are, for the most part, unknown. Performing predicted climate change scenario simulations (periodic and chronic heat and drought spells [HDSs] applied under elevated [CO2]), we analyzed volatile organic compound emissions, photosynthetic performance, leaf growth, and overall carbon (C) gain of poplar genotypes emitting (IE) and nonemitting (NE) isoprene. We aimed (1) to evaluate the proposed beneficial effect of isoprene emission on plant stress mitigation and recovery capacity and (2) to estimate the cumulative net C gain under the projected future climate. During HDSs, the chloroplastidic electron transport rate of NE plants became impaired, while IE plants maintained high values similar to unstressed controls. During recovery from HDS episodes, IE plants reached higher daily net CO2 assimilation rates compared with NE genotypes. Irrespective of the genotype, plants undergoing chronic HDSs showed the lowest cumulative C gain. Under control conditions simulating ambient [CO2], the C gain was lower in the IE plants than in the NE plants. In summary, the data on the overall C gain and plant growth suggest that the beneficial function of isoprene emission in poplar might be of minor importance to mitigate predicted short-term climate extremes under elevated [CO2]. Moreover, we demonstrate that an analysis of the canopy-scale dynamics of isoprene emission and photosynthetic performance under multiple stresses is essential to understand the overall performance under proposed future conditions. PMID:26162427

  15. Predicting the Effects of Short-Term Photovoltaic Variability on Power System Frequency for Systems with Integrated Energy Storage

    NASA Astrophysics Data System (ADS)

    Traube, Joshua White

    The percentage of electricity supplied by photovoltaic (PV) generators is steadily rising in power systems worldwide. This rise in PV penetration may lead to larger fluctuations in power system frequency due to variability in PV generator output at time scales that fall between the inertial damping and automatic generation control (AGC) responses of power systems. To reduce PV generator variability, active power controls can be implemented in the power electronic inverters that interface PV generators to the power system. Although various types of active power controls have been developed, no standard methodology exists for evaluating the effectiveness of these controls at improving power system frequency regulation. This dissertation presents a method for predicting the effects of short-term PV variability on power system frequency for a PV generator with active power control provided by integrated energy storage. A custom model of a PV generator with integrated energy storage is implemented in a power system dynamic simulator and validated through experiments with a grid emulator. The model is used to predict the effects of short-term PV variability on the frequency of the IEEE 9-bus test power system modified to include a PV generator with integrated energy storage. In addition, this dissertation utilizes linear analysis of power system frequency control to predict worst-case frequency deviations as a function of the amount of energy storage integrated into PV generators. Through simulation and emulation on a scaled experimental prototype, the maximum frequency deviation caused by the PV generator with a small amount of integrated energy storage is found to be approximately 33% lower than the maximum frequency deviation caused by the PV generator alone. Through linear analysis it is shown that by adding only 36.7 kWh of integrated energy storage to a 1.2 MW PV system, the worst-case frequency deviation on the IEEE 9-bus test system can be reduced 65% from 0

  16. Short-term environmental variability in cold-water coral habitat at Viosca Knoll, Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Davies, Andrew J.; Duineveld, Gerard C. A.; van Weering, Tjeerd C. E.; Mienis, Furu; Quattrini, Andrea M.; Seim, Harvey E.; Bane, John M.; Ross, Steve W.

    2010-02-01

    The Lophelia pertusa community at Viosca Knoll (VK826) is the most extensive found to date in the Gulf of Mexico. As part of a multi-disciplinary study, the physical setting of this area was described using benthic landers, CTD transects and remotely operated vehicle observations. The site was broadly characterised into three main habitats: (1) dense coral cover that resembles biogenic reef complexes, (2) areas of sediment, and (3) authigenic carbonate blocks with sparse coral and chemosynthetic communities. The coral communities were dominated by L. pertusa but also contained numerous solitary coral species. Over areas that contained L. pertusa, the environmental conditions recorded were similar to those associated with communities in the north-eastern Atlantic, with temperature (8.5-10.6 °C) and salinity (˜35) falling within the known species niche for L. pertusa. However, dissolved oxygen concentrations (2.7-2.8 ml l -1) and density ( σ Θ, 27.1-27.2 kg m -3) were lower and mass fluxes from sediment trap data appeared much higher (4002-4192 mg m -2 d -1). Yet, this species still appears to thrive in this region, suggesting that L. pertusa may not be as limited by lower dissolved oxygen concentrations as previously thought. The VK826 site experienced sustained eastward water flow of 10-30 cm s -1 over the 5-day measurement period but was also subjected to significant short-term variability in current velocity and direction. In addition, two processes were observed that caused variability in salinity and temperature; the first was consistent with internal waves that caused temperature variations of 0.8 °C over 5-11 h periods. The second was high-frequency variability (20-30 min periods) in temperature recorded only at the ALBEX site. A further pattern observed over the coral habitat was the presence of a 24 h diel vertical migration of zooplankton that may form part of a food chain that eventually reaches the corals. The majority of detailed studies concerning

  17. Change in Measured Noncognitive Variables: A Quantitative Examination of the Influence of Short-Term Study Abroad Experiences

    ERIC Educational Resources Information Center

    Motley, Reginald James

    2013-01-01

    Students have different motivations for participating in education abroad experiences. Short-term study abroad programs offer students the opportunity to experience education abroad without spending an entire semester or year abroad. As a result of these opportunities, short-term study abroad programs have emerged to meet the demands for students…

  18. Short-term Climate Change, Recent Economic Slowdown and Surface Ozone in the US for the Past Decades

    NASA Astrophysics Data System (ADS)

    Chu, S.; Evangelista, M.

    2012-12-01

    Stagnant high pressure systems in the warm season have long been known to be conducive to high surface ozone concentrations. Variation in the strength and duration of these high pressure systems also provides a good indicator for short-term climate changes. In this study, we have developed a stagnant high pressure index (SH) to examine whether significant changes in ozone conducive conditions in the past 3 decades have actually been observed. We compared the trend of SH index with annual ozone design values in 45 major metropolitan areas nationwide to see what impact it had on efforts to control surface ozone for the past three decades. Our results show a significant increase in SH index in the past decade - a clear indication of current climate change to a more ozone conducive atmosphere. We also found that the accelerated decline in ambient ozone trend from 2007 to 2010 could not be explained by meteorology and existing emission controls except by essentially the recent economic slowdowns. However, the encouraging fact is that even with the rapid increase of stagnant high pressure systems in the past decade, ozone control strategies still managed to keep a steady improvement in ozone air quality in the U.S.

  19. Fine-scale refuges can buffer demographic and genetic processes against short-term climatic variation and disturbance: a 22-year case study of an arboreal marsupial.

    PubMed

    Banks, Sam C; Lorin, Thibault; Shaw, Robyn E; McBurney, Lachlan; Blair, David; Blyton, Michaela D J; Smith, Annabel L; Pierson, Jennifer C; Lindenmayer, David B

    2015-08-01

    Ecological disturbance and climate are key drivers of temporal dynamics in the demography and genetic diversity of natural populations. Microscale refuges are known to buffer species' persistence against environmental change, but the effects of such refuges on demographic and genetic patterns in response to short-term environmental variation are poorly understood. We quantified demographic and genetic responses of mountain brushtail possums (Trichosurus cunninghami) to rainfall variability (1992-2013) and to a major wildfire. We hypothesized that there would be underlying differences in demographic and genetic processes between an unburnt mesic refuge and a topographically exposed zone that was burnt in 2009. Fire caused a 2-year decrease in survival in the burnt zone, but the population grew after the fire due to immigration, leading to increased expected heterozygosity. We documented a fire-related behavioural shift, where the rate of movement by individuals in the unburnt refuge to the burnt zone decreased after fire. Irrespective of the fire, there were long-term differences in demographic and genetic parameters between the mesic/unburnt refuge and the nonmesic/burnt zone. Survival was high and unaffected by rainfall in the refuge, but lower and rainfall-dependent in the nonmesic zone. Net movement of individuals was directional, from the mesic refuge to the nonmesic zone, suggesting fine-scale source-sink dynamics. There were higher expected heterozygosity (HE ) and temporal genetic stability in the refuge, but lower HE and marked temporal genetic structure in the exposed habitat, consistent with reduced generational overlap caused by elevated mortality and immigration. Thus, fine-scale refuges can mediate the short-term demographic and genetic effects of climate and ecological disturbance. PMID:26089175

  20. Improved water allocation utilizing probabilistic climate forecasts: Short-term water contracts in a risk management framework

    NASA Astrophysics Data System (ADS)

    Sankarasubramanian, A.; Lall, Upmanu; Souza Filho, Francisco Assis; Sharma, Ashish

    2009-11-01

    Probabilistic, seasonal to interannual streamflow forecasts are becoming increasingly available as the ability to model climate teleconnections is improving. However, water managers and practitioners have been slow to adopt such products, citing concerns with forecast skill. Essentially, a management risk is perceived in "gambling" with operations using a probabilistic forecast, while a system failure upon following existing operating policies is "protected" by the official rules or guidebook. In the presence of a prescribed system of prior allocation of releases under different storage or water availability conditions, the manager has little incentive to change. Innovation in allocation and operation is hence key to improved risk management using such forecasts. A participatory water allocation process that can effectively use probabilistic forecasts as part of an adaptive management strategy is introduced here. Users can express their demand for water through statements that cover the quantity needed at a particular reliability, the temporal distribution of the "allocation," the associated willingness to pay, and compensation in the event of contract nonperformance. The water manager then assesses feasible allocations using the probabilistic forecast that try to meet these criteria across all users. An iterative process between users and water manager could be used to formalize a set of short-term contracts that represent the resulting prioritized water allocation strategy over the operating period for which the forecast was issued. These contracts can be used to allocate water each year/season beyond long-term contracts that may have precedence. Thus, integrated supply and demand management can be achieved. In this paper, a single period multiuser optimization model that can support such an allocation process is presented. The application of this conceptual model is explored using data for the Jaguaribe Metropolitan Hydro System in Ceara, Brazil. The performance

  1. Shifts in the suitable habitat available for brown trout (Salmo trutta L.) under short-term climate change scenarios.

    PubMed

    Muñoz-Mas, R; Lopez-Nicolas, A; Martínez-Capel, F; Pulido-Velazquez, M

    2016-02-15

    The impact of climate change on the habitat suitability for large brown trout (Salmo trutta L.) was studied in a segment of the Cabriel River (Iberian Peninsula). The future flow and water temperature patterns were simulated at a daily time step with M5 models' trees (NSE of 0.78 and 0.97 respectively) for two short-term scenarios (2011-2040) under the representative concentration pathways (RCP 4.5 and 8.5). An ensemble of five strongly regularized machine learning techniques (generalized additive models, multilayer perceptron ensembles, random forests, support vector machines and fuzzy rule base systems) was used to model the microhabitat suitability (depth, velocity and substrate) during summertime and to evaluate several flows simulated with River2D©. The simulated flow rate and water temperature were combined with the microhabitat assessment to infer bivariate habitat duration curves (BHDCs) under historical conditions and climate change scenarios using either the weighted usable area (WUA) or the Boolean-based suitable area (SA). The forecasts for both scenarios jointly predicted a significant reduction in the flow rate and an increase in water temperature (mean rate of change of ca. -25% and +4% respectively). The five techniques converged on the modelled suitability and habitat preferences; large brown trout selected relatively high flow velocity, large depth and coarse substrate. However, the model developed with support vector machines presented a significantly trimmed output range (max.: 0.38), and thus its predictions were banned from the WUA-based analyses. The BHDCs based on the WUA and the SA broadly matched, indicating an increase in the number of days with less suitable habitat available (WUA and SA) and/or with higher water temperature (trout will endure impoverished environmental conditions ca. 82% of the days). Finally, our results suggested the potential extirpation of the species from the study site during short time spans. PMID:26674698

  2. MAGIC detection of short-term variability of the high-peaked BL Lac object 1ES 0806+524

    NASA Astrophysics Data System (ADS)

    Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Bangale, P.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Lotto, B.; de Oña Wilhelmi, E.; Delgado Mendez, C.; Di Pierro, F.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher, D.; Elsaesser, D.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Godinović, N.; González Muñoz, A.; Gozzini, S. R.; Hadasch, D.; Hanabata, Y.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Idec, W.; Kadenius, V.; Kellermann, H.; Knoetig, M. L.; Kodani, K.; Konno, Y.; Krause, J.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; López-Oramas, A.; Lorenz, E.; Lozano, I.; Makariev, M.; Mallot, K.; Maneva, G.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Munar-Adrover, P.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nilsson, K.; Nishijima, K.; Noda, K.; Orito, R.; Overkemping, A.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rodriguez Garcia, J.; Saito, T.; Saito, K.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Stamerra, A.; Steinbring, T.; Strzys, M.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Torres, D. F.; Toyama, T.; Treves, A.; Vogler, P.; Will, M.; Zanin, R.; Berger, K.; Buson, S.; D'Ammando, F.; Gasparrini, D.; Hovatta, T.; Max-Moerbeck, W.; Readhead, A.; Richards, J.

    2015-07-01

    The high-frequency-peaked BL Lac (HBL) 1ES 0806+524 (z = 0.138) was discovered in very high energy (VHE) γ-rays in 2008. Until now, the broad-band spectrum of 1ES 0806+524 has been only poorly characterized, in particular at high energies. We analysed multiwavelength observations from γ-rays to radio performed from 2011 January to March, which were triggered by the high activity detected at optical frequencies. These observations constitute the most precise determination of the broad-band emission of 1ES 0806+524 to date. The stereoscopic Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) observations yielded a γ-ray signal above 250 GeV of (3.7 ± 0.7) per cent of the Crab Nebula flux with a statistical significance of 9.9σ. The multiwavelength observations showed significant variability in essentially all energy bands, including a VHE γ-ray flare that lasted less than one night, which provided unprecedented evidence for short-term variability in 1ES 0806+524. The spectrum of this flare is well described by a power law with a photon index of 2.97 ± 0.29 between ˜150 GeV and 1 TeV and an integral flux of (9.3 ± 1.9) per cent of the Crab nebula flux above 250 GeV. The spectrum during the non-flaring VHE activity is compatible with the only available VHE observation performed in 2008 with VERITAS when the source was in a low optical state. The broad-band spectral energy distribution can be described with a one-zone synchrotron self-Compton model with parameters typical for HBLs, indicating that 1ES 0806+524 is not substantially different from the HBLs previously detected.

  3. Short-term acute effects of gutkha chewing on heart rate variability among young adults: A cross-sectional study

    PubMed Central

    Itagi, Afreen Begum H; Arora, Dimple; Patil, Navin A; Bailwad, Sandeep Anant; Yunus, GY; Goel, Ankit

    2016-01-01

    Background and Objectives: An increase in the consumption of smokeless tobacco has been noticed among high school, college students, and adults. Despite the antiquity and popularity of chewing tobacco in India, its effects have not been investigated systematically in humans. The aim of this study was to investigate acute effects of gutkha chewing on heart rate variability (HRV) among healthy young adults. Materials and Methods: A total of 60 young adult males were included in the study. Each individual was asked to chew tobacco and subjected to HRV analysis. HRV analysis using short-term electrocardiogram recording was used to measure HRV parameters before gutkha chewing and at 5, 15, and 30 min after chewing tobacco. One-way analysis of variance and paired t-test was used to assess changes over time. Results: There was a significant increase in heart rate (HR) during tobacco chewing. Mean HR at baseline measured 73.0 ± 6.2 bpm. There was a rise in mean HR to 83.7 ± 9.1 bpm at 5 min during tobacco chewing and gradual reduction to baseline observed after 15 min followed by no significant change till 30 min. The normalized low-frequency power and LF/high-frequency (HF) power ratio were elevated after 5 min; however, normalized HF power was reduced after 5 min tobacco chewing. Conclusion: Gutkha is closely associated with traditional cardiovascular risk factors as detected by a transient enhancing sympathetic activity during tobacco chewing in the form of increased HRV parameters or an imbalance between sympathetic and parasympathetic neural activity among healthy young adults. PMID:26958522

  4. Short-term X-ray spectral variability of the quasar PDS 456 observed in a low-flux state

    NASA Astrophysics Data System (ADS)

    Matzeu, G. A.; Reeves, J. N.; Nardini, E.; Braito, V.; Costa, M. T.; Tombesi, F.; Gofford, J.

    2016-05-01

    We present a detailed analysis of a recent, 2013 Suzaku campaign on the nearby (z = 0.184) luminous (Lbol ˜ 1047 erg s-1) quasar PDS 456. This consisted of three observations, covering a total duration of ˜1 Ms and a net exposure of 455 ks. During these observations, the X-ray flux was unusually low, suppressed by a factor of >10 in the soft X-ray band when compared to previous observations. We investigated the broad-band continuum by constructing a spectral energy distribution (SED), making use of the optical/UV photometry and hard X-ray spectra from the later simultaneous XMM-Newton and NuSTAR campaign in 2014. The high-energy part of this low-flux SED cannot be accounted for by physically self-consistent accretion disc and corona models without attenuation by absorbing gas, which partially covers a substantial fraction of the line of sight towards the X-ray continuum. At least two layers of absorbing gas are required, of column density log (NH,low/cm-2) = 22.3 ± 0.1 and log (NH,high/cm-2) = 23.2 ± 0.1, with average line-of-sight covering factors of ˜80 per cent (with typical ˜5 per cent variations) and 60 per cent (±10-15 per cent), respectively. During these observations PDS 456 displays significant short-term X-ray spectral variability, on time-scales of ˜100 ks, which can be accounted for by variable covering of the absorbing gas along the line of sight. The partial covering absorber prefers an outflow velocity of v_pc = 0.25^{+0.01}_{-0.05} c at the >99.9 per cent confidence level over the case where vpc = 0. This is consistent with the velocity of the highly ionized outflow responsible for the blueshifted iron K absorption profile. We therefore suggest that the partial covering clouds could be the denser, or clumpy part of an inhomogeneous accretion disc wind. Finally estimates are placed upon the size-scale of the X-ray emission region from the source variability. The radial extent of the X-ray emitter is found to be of the order ˜15-20Rg

  5. Spherical Harmonic Analysis of Short-Term Variability in the External and Induced Geomagnetic Field, with Supermag.

    NASA Astrophysics Data System (ADS)

    Dorrian, G.; Wild, J. A.; Freeman, M. P.; Shore, R.; Gjerloev, J. W.

    2014-12-01

    We present a methodology for developing spherical harmonic models of short-term variations in the external and induced geomagnetic field. The method uses data from the SuperMAG global magnetometer network, which is provided at 1-minute time resolution. We examine some of the technical challenges encountered in the method development and some initial results are discussed. Results are compared with those from a climatological study running in parallel, which also utilizes SuperMAG data.

  6. Role of serial order in the impact of talker variability on short-term memory: testing a perceptual organization-based account.

    PubMed

    Hughes, Robert W; Marsh, John E; Jones, Dylan M

    2011-11-01

    In two experiments, we examined the impact of the degree of match between sequential auditory perceptual organization processes and the demands of a short-term memory task (memory for order vs. item information). When a spoken sequence of digits was presented so as to promote its perceptual partitioning into two distinct streams by conveying it in alternating female (F) and male (M) voices (FMFMFMFM)--thereby disturbing the perception of true temporal order--recall of item order was greatly impaired (as compared to recall of item identity). Moreover, an order error type consistent with the formation of voice-based streams was committed more quickly in the alternating-voice condition (Exp. 1). In contrast, when the perceptual organization of the sequence mapped well onto an optimal two-group serial rehearsal strategy--by presenting the two voices in discrete clusters (FFFFMMMM)--order, but not item, recall was enhanced (Exp. 2). The results are consistent with the view that the degree of compatibility between perceptual and deliberate sequencing processes is a key determinant of serial short-term memory performance. Alternative accounts of talker variability effects in short-term memory, based on the concept of a dedicated phonological short-term store and a capacity-limited focus of attention, are also reviewed. PMID:21638105

  7. The response of the MLS mesospheric daytime hydroxyl radical and water vapor to the short-term solar irradiance variability

    NASA Astrophysics Data System (ADS)

    Shapiro, A. V.; Rozanov, E.; Shapiro, A.; Wang, S.; Egorova, T. A.; Schmutz, W. K.; Peter, T.

    2011-12-01

    Solar radiation, which is the main energy source in the terrestrial atmosphere, is highly variable on different time-scales. The variations of the SSI may have substantial impact on chemical and physical processes in the atmosphere. The mesospheric hydroxyl radical (OH), which is the main ozone destructor, is produced due to the photolysis of the water vapor (H2O) by highly variable short wave solar radiation. Chemistry-climate models suggest strong response of the mesospheric OH and H2O caused by the solar irradiance variability. However the response was not yet defined with observed data. We analyzed the response of the tropical mean OH and H2O data observed by Aura Microwave Limb Sounder (MLS) to the solar irradiance variations during rotational cycle. We performed the analysis for the two time periods. The data from December 2004 to December 2005 were used to estimate the OH and H2O responses to the solar irradiance variability in high solar activity conditions (when the 27-day rotational cycle is well pronounced). The response for the solar minimum conditions (when the 27-day rotational cycle is vague) was considered using the data from November 2008 to November 2009. We found, for the first time, that during the period of the high solar activity the daily time series of the mesospheric OH correlate well with the solar irradiance at zero time-lag and the correlation coefficient reaches 0.79 at 76-82 km. The H2O for the same period anticorrelates with the solar irradiance at about 6-7 days time-lag with the correlation coefficient up to -0.7. At the same time the OH and H2O responses are negligible for the solar minimum period. This confirms that the 27-day solar cycles in OH, H2O and solar irradiance are physically connected.

  8. Deglacial-Holocene short-term variability in sea-ice distribution on the Eurasian shelf (Arctic Ocean) - An IP25 biomarker reconstruction.

    NASA Astrophysics Data System (ADS)

    Hörner, Tanja; Stein, Ruediger; Fahl, Kirsten

    2016-04-01

    Four well-dated sediment cores from the Eurasian continental shelf, i.e., the Kara Sea (Cores BP99/07 and BP00/07) and Laptev Sea (Cores PS51/154 and PS51/159), were selected for high-resolution reconstruction of past Arctic environmental conditions during the deglacial-Holocene time interval. These marginal seas are strongly affected by the post-glacial sea-level rise of about 120m. The major focus of our study was the reconstruction of the paleo-sea-ice distribution as sea-ice plays a key role within the modern and past climate system. For reconstruction of paleo-sea ice, the sea-ice proxy IP25 in combination with open-water phytoplankton biomarkers was used (for approach see Belt et al., 2007; Müller et al., 2009, 2011). In addition, specific sterols were determined to reconstruct changes in river run-off and biological production. The post-glacial sea-level rise is especially reflected in prominent decrease in terrigenous biomarkers. Deglacial variations in sea-ice cover sustained for thousand of years, mostly following climatic changes like the Bølling/Allerød (14.7-12.9 ka), Younger Dryas (12.9-11.6 ka) and Holocene warm phase (10-8 ka). Superimposed on a (Late) Holocene cooling trend, short-term fluctuations in sea-ice cover (on centennial scale) are distinctly documented in the distal/off-shore Core BP00/07 from the Kara Sea, less pronounced in the proximal/near-shore Core PS99/07 and in the Laptev Sea cores. Interestingly, this short-term variability in sea-ice cover correlates quite well to changes in Siberian river run-off (e.g., Stein et al. 2004), pointing to a direct linkage between precipitation (atmospheric circulation) and sea-ice formation. References Belt, S.T., Massé, G., Rowland, S.J., Poulin, M., Michel, C., LeBlanc, B., 2007. A novel chemical fossil of palaeo sea ice: IP25. Organic Geochemistry 38, 16-27. Müller, J., Masse, G., Stein, R., Belt, S.T., 2009. Variability of sea-ice conditions in the Fram Strait over the past 30,000 years

  9. Ultra-Short-Term Heart Rate Variability Indexes at Rest and Post-Exercise in Athletes: Evaluating the Agreement with Accepted Recommendations

    PubMed Central

    Esco, Michael R.; Flatt, Andrew A.

    2014-01-01

    The purpose of this study was to evaluate the agreement of the vagal-related heart rate variability index, log-transformed root mean square of successive R-R intervals (lnRMSSD), measured under ultra-short-term conditions (< 60 seconds) with conventional longer term recordings of 5 minutes in collegiate athletes under resting and post-exercise conditions. Electrocardiographic readings were collected from twenty-three athletes within 5-minute segments at rest and at 25-30 minutes of supine recovery following a maximal exercise test. From each 5-minute segment, lnRMSSD was recorded as the criterion measure. Within each 5-minute segment, lnRMSSD was also determined from randomly selected ultra-short-term segments of 10-, 30-, and 60-seconds in length, which were compared to the criterion. When compared to the criterion measures, the significant intraclass correlation (from 0.98 to 0.81, p < 0.05) and typical error (from 0.11 to 0.34) increased as ultra-short-term measurement duration decreased (i.e., from 60 seconds to 10 seconds). In addition, the limits of agreement (Bias ± 1.98 SD) increased as ultra-short-term lnRMSSD duration decreased as follows: 0.00 ± 0.22 ms, -0.07 ± 0.41 ms, -0.20 ± 0.94 ms for the 60-, 30-, and 10-second pre-exercise segments, respectively, and -0.15 ± 0.39 ms, -0.14 ± 0.53 ms, -0.12 ± 0.76 ms for the 60-, 30-, and 10-second post-exercise segments, respectively. This study demonstrated that as ultra-short-term measurement duration decreased from 60 seconds to 10 seconds, the agreement to the criterion decreased. Therefore, 60 seconds appears to be an acceptable recording time for lnRMSSD data collection in collegiate athletes. Key Points The log-transformed root mean square of successive R-R intervals (lnRMSSD) is a vagal-related heart rate variability index that has become a promising method for monitoring individual adaptation to training when measured during resting or post-exercise conditions. This study demonstrated that ln

  10. Winchester/Camberley Homes New Construction Test House Design, Construction, and Short-Term Testing in a Mixed-Humid Climate

    SciTech Connect

    Mallay, D.; Wiehagen, J.; Wood, A.

    2012-10-01

    The NAHB Research Center partnered with production builder Winchester/Camberley Homes to build a new construction test house in the mixed-humid climate zone of Silver Spring, MD in June 2011. The goal for this house was to improve energy efficiency by 30% over the Building America B10 benchmark through an optimized energy solutions package design that could be constructed on a production basis. This report outlines the features of this house, discusses the energy efficient design, and reports on short-term testing results.

  11. Sensitivity of the air-sea CO2 exchange in the Baltic Sea and Danish inner waters to atmospheric short-term variability

    NASA Astrophysics Data System (ADS)

    Lansø, A. S.; Bendtsen, J.; Christensen, J. H.; Sørensen, L. L.; Chen, H.; Meijer, H. A. J.; Geels, C.

    2015-05-01

    Minimising the uncertainties in estimates of air-sea CO2 exchange is an important step toward increasing the confidence in assessments of the CO2 cycle. Using an atmospheric transport model makes it possible to investigate the direct impact of atmospheric parameters on the air-sea CO2 flux along with its sensitivity to, for example, short-term temporal variability in wind speed, atmospheric mixing height and atmospheric CO2 concentration. With this study, the importance of high spatiotemporal resolution of atmospheric parameters for the air-sea CO2 flux is assessed for six sub-basins within the Baltic Sea and Danish inner waters. A new climatology of surface water partial pressure of CO2 (pCO2w) has been developed for this coastal area based on available data from monitoring stations and on-board pCO2w measuring systems. Parameterisations depending on wind speed were applied for the transfer velocity to calculate the air-sea CO2 flux. Two model simulations were conducted - one including short-term variability in atmospheric CO2 (VAT), and one where it was not included (CAT). A seasonal cycle in the air-sea CO2 flux was found for both simulations for all sub-basins with uptake of CO2 in summer and release of CO2 to the atmosphere in winter. During the simulated period 2005-2010, the average annual net uptake of atmospheric CO2 for the Baltic Sea, Danish straits and Kattegat was 287 and 471 Gg C yr-1 for the VAT and CAT simulations, respectively. The obtained difference of 184 Gg C yr-1 was found to be significant, and thus ignoring short-term variability in atmospheric CO2 does have a sizeable effect on the air-sea CO2 exchange. The combination of the atmospheric model and the new pCO2w fields has also made it possible to make an estimate of the marine part of the Danish CO2 budget for the first time. A net annual uptake of 2613 Gg C yr-1 was found for the Danish waters. A large uncertainty is connected to the air-sea CO2 flux in particular caused by the transfer

  12. Sensitivity of the air-sea CO2 exchange in the Baltic Sea and Danish inner waters to atmospheric short term variability

    NASA Astrophysics Data System (ADS)

    Lansø, A. S.; Bendtsen, J.; Christensen, J. H.; Sørensen, L. L.; Chen, H.; Meijer, H. A. J.; Geels, C.

    2014-12-01

    Minimising the uncertainties in estimates of air-sea CO2 exchange is an important step toward increasing the confidence in assessments of the CO2 cycle. Using an atmospheric transport model makes it possible to investigate the direct impact of atmospheric parameters on the air-sea CO2 flux along with its sensitivity to e.g. short-term temporal variability in wind speed, atmospheric mixing height and the atmospheric CO2 concentration. With this study the importance of high spatiotemporal resolution of atmospheric parameters for the air-sea CO2 flux is assessed for six sub-basins within the Baltic Sea and Danish inner waters. A new climatology of surface water partial pressure of CO2 (pCO2) has been developed for this coastal area based on available data from monitoring stations and underway pCO2 measuring systems. Parameterisations depending on wind speed were applied for the transfer velocity to calculate the air-sea CO2 flux. Two model simulations were conducted - one including short term variability in atmospheric CO2 (VAT), and one where it was not included (CAT). A seasonal cycle in the air-sea CO2 flux was found for both simulations for all sub-basins with uptake of CO2 in summer and release of CO2 to the atmosphere in winter. During the simulated period 2005-2010 the average annual net uptake of atmospheric CO2 for the Baltic Sea, Danish Straits and Kattegat was 287 and 471 Gg C yr-1 for the VAT and CAT simulations, respectively. The obtained difference of 184 Gg C yr-1 was found to be significant, and thus ignoring short term variability in atmospheric CO2 does have a sizeable effect on the air-sea CO2 exchange. The combination of the atmospheric model and the new pCO2 fields has also made it possible to make an estimate of the marine part of the Danish CO2 budget for the first time. A net annual uptake of 2613 Gg C yr-1 was found for the Danish waters. A large uncertainty is connected to the air-sea CO2 flux in particular caused by the transfer velocity

  13. No effect of short-term amino acid supplementation on variables related to skeletal muscle damage in 100 km ultra-runners - a randomized controlled trial

    PubMed Central

    2011-01-01

    Background The purpose of this study was to investigate the effect of short-term supplementation of amino acids before and during a 100 km ultra-marathon on variables of skeletal muscle damage and muscle soreness. We hypothesized that the supplementation of amino acids before and during an ultra-marathon would lead to a reduction in the variables of skeletal muscle damage, a decrease in muscle soreness and an improved performance. Methods Twenty-eight experienced male ultra-runners were divided into two groups, one with amino acid supplementation and the other as a control group. The amino acid group was supplemented a total of 52.5 g of an amino acid concentrate before and during the 100 km ultra-marathon. Pre- and post-race, creatine kinase, urea and myoglobin were determined. At the same time, the athletes were asked for subjective feelings of muscle soreness. Results Race time was not different between the groups when controlled for personal best time in a 100 km ultra-marathon. The increases in creatine kinase, urea and myoglobin were not different in both groups. Subjective feelings of skeletal muscle soreness were not different between the groups. Conclusions We concluded that short-term supplementation of amino acids before and during a 100 km ultra-marathon had no effect on variables of skeletal muscle damage and muscle soreness. PMID:21473783

  14. Perceptual-Gestural (Mis)Mapping in Serial Short-Term Memory: The Impact of Talker Variability

    ERIC Educational Resources Information Center

    Hughes, Robert W.; Marsh, John E.; Jones, Dylan M.

    2009-01-01

    The mechanisms underlying the poorer serial recall of talker-variable lists (e.g., alternating female-male voices) as compared with single-voice lists were examined. We tested the novel hypothesis that this "talker variability effect" arises from the tendency for perceptual organization to partition the list into streams based on voice such that…

  15. A search for short-term variability in the very high energy γ-ray emission from the Crab nebula

    NASA Astrophysics Data System (ADS)

    O'Faoláin de Bhróithe, Anna; VERITAS Collaboration

    2012-12-01

    The Crab Nebula has long been considered a standard candle in high energy astrophysics, but in recent years this assumpation has been strongly contradicted in keV-GeV wavebands. In light of these developments, a search for variability is being performed on the nebula at Very High Energies (VHE; E > 300 GeV), the preliminary results of which are presented here. This initial study is based on 10 years (2001-2011) of archival data from the Whipple 10m telescope. The data set was searched for evidence of variability on the timescales of 1, 7, and 14 days. To date, no significant flaring activity has been found, but simulations are in progress to determine the level of variability that would be detected.

  16. Short-term X-ray variability of the globular cluster source 4U 1820 - 30 (NGC 6624)

    NASA Technical Reports Server (NTRS)

    Stella, L.; Kahn, S. M.; Grindlay, J. E.

    1984-01-01

    Analytical techniques for improved identification of the temporal and spectral variability properties of globular cluster and galactic bulge X-ray sources are described in terms of their application to a large set of observations of the source 4U 1820 - 30 in the globular cluster NGC 6624. The autocorrelation function, cross-correlations, time skewness function, erratic periodicities, and pulse trains are examined. The results are discussed in terms of current models with particular emphasis on recent accretion disk models. It is concluded that the analyzed observations provide the first evidence for shot-noise variability in a globular cluster X-ray source.

  17. Short-term Variability in Outpatient Pain Intensity Scores in a National Sample of Older Veterans with Chronic Pain

    PubMed Central

    Dobscha, Steven K.; Morasco, Benjamin J.; Kovas, Anne E.; Peters, Dawn M.; Hart, Kyle; McFarland, Bentson H.

    2015-01-01

    Objective The Department of Veterans Affairs (VA) uses the 11-point pain numeric rating scale (NRS) to gather pain intensity information from veterans at outpatient appointments. Yet, little is known about how NRS scores may vary over time within individuals; NRS variability may have important ramifications for treatment planning. Our main objective was to describe variability in NRS scores within a one-month timeframe, as obtained during routine outpatient care in older patients with chronic pain treated in VA hospitals. A secondary objective was to explore for patient characteristics associated with within-month NRS score variability. Design Retrospective cohort study. Subjects National sample of veterans 65 years or older seen in VA in 2010 who had multiple elevated NRS scores indicating chronic pain. Methods VA datasets were used to identify the sample and demographic and clinical variables including NRS scores. For the main analysis, we identified subjects with 2 or more NRS scores obtained in each of 2 or more months in a 12 month period; we examined ranges in NRS scores across the first 2 qualifying months. Results Among 4,336 individuals in the main analysis cohort, the mean and median of the average NRS score range across the two months were 2.7 and 2.5, respectively. In multivariable models, main significant predictors of within-month NRS score variability were baseline pain intensity, overall medical comorbidity, and being divorced/separated. Conclusions The majority of patients in the sample had clinically meaningful variation in pain scores within a given month. This finding highlights the need for clinicians and their patients to consider multiple NRS scores when making chronic pain treatment decisions. PMID:25545398

  18. Relationship Between Changes in Pulse Pressure and Frequency Domain Components of Heart Rate Variability During Short-Term Left Ventricular Pacing in Patients with Cardiac Resynchronization Therapy

    PubMed Central

    Urbanek, Bożena; Ruta, Jan; Kudryński, Krzysztof; Ptaszyński, Paweł; Klimczak, Artur; Wranicz, Jerzy Krzysztof

    2016-01-01

    Background The aim of the study was to explore the relationship between changes in pulse pressure (PP) and frequency domain heart rate variability (HRV) components caused by left ventricular pacing in patients with implanted cardiac resynchronization therapy (CRT). Material/Methods Forty patients (mean age 63±8.5 years) with chronic heart failure (CHF) and implanted CRT were enrolled in the study. The simultaneous 5-minute recording of beat-to-beat arterial systolic and diastolic blood pressure (SBP and DBP) by Finometer and standard electrocardiogram with CRT switched off (CRT/0) and left ventricular pacing (CRT/LV) was performed. PP (PP=SBP-DBP) and low- and high-frequency (LF and HF) HRV components were calculated, and the relationship between these parameters was analyzed. Results Short-term CRT/LV in comparison to CRT/0 caused a statistically significant increase in the values of PP (P<0.05), LF (P<0.05), and HF (P<0.05). A statistically significant correlation between ΔPP and ΔHF (R=0.7384, P<0.05) was observed. The ΔHF of 6 ms2 during short-term CRT/LV predicted a PP increase of ≥10% with 84.21% sensitivity and 85.71% specificity. Conclusions During short-term left ventricular pacing in patients with CRT, a significant correlation between ΔPP and ΔHF was observed. ΔHF ≥6 ms2 may serve as a tool in the selection of a suitable site for placement of a left ventricular lead. PMID:27305349

  19. Heart rate variability in conscious neonatal swine: spectral features and responses to short-term intermittent hypoxia

    PubMed Central

    Sica, Anthony L; Zhao, Ning

    2006-01-01

    Background Spectral analysis of the cardiac time series has been used as a tool for assessing levels of parasympathetic and sympathetic modulation of the sinoatrial node. In the present investigation we evaluated daily changes in heart rate variability spectra in conscious neonatal piglets that were either neurally intact (n = 5) or had undergone right stellate ganglionectomy (n = 5). The partial stellectomized animals and their intact litter mates were exposed to four days of intermittent hypoxia, each day comprising nine episodes of hypoxia alternating with nine episodes of normoxia. A time control group (n = 7) comprised animals from different litters that were not exposed to intermittent hypoxia. We hypothesized that exposure to intermittent hypoxia would increase sympathetic efferent neuronal modulation of heart rate variability spectra in neurally intact animals and in those with right stellate ganglionectomy, and that his effect would be observed in heart rate variability spectra computed from baseline recordings. Results Overall, heart rate variability spectra during baseline conditions were dominated by high frequency activity, a reflection of parasympathetic efferent neuronal innervation and linkage to the ventilatory cycle manifested as respiratory sinus arrhythmia. Exposure to intermittent hypoxia did not alter daily baseline spectral features that would indicate an increase of sympathetic cardiac activity: low frequency (0.05 – 0.15 Hz) activity was unaffected and the ratio of low- to -high frequency activity remained less than unity indicating a predominance of high frequency activity. The resultant spectra were remarkably similar despite differences in cardiac sympathetic efferent neuronal innervation and experimental treatment. When spectra were computed from cardiac time series during representative hypoxic episodes, significant increases in activity across the low frequency region (0.05 – 0.15 Hz) of heart rate variability spectra were noted

  20. Plants, birds and butterflies: short-term responses of species communities to climate warming vary by taxon and with altitude.

    PubMed

    Roth, Tobias; Plattner, Matthias; Amrhein, Valentin

    2014-01-01

    As a consequence of climate warming, species usually shift their distribution towards higher latitudes or altitudes. Yet, it is unclear how different taxonomic groups may respond to climate warming over larger altitudinal ranges. Here, we used data from the national biodiversity monitoring program of Switzerland, collected over an altitudinal range of 2500 m. Within the short period of eight years (2003-2010), we found significant shifts in communities of vascular plants, butterflies and birds. At low altitudes, communities of all species groups changed towards warm-dwelling species, corresponding to an average uphill shift of 8 m, 38 m and 42 m in plant, butterfly and bird communities, respectively. However, rates of community changes decreased with altitude in plants and butterflies, while bird communities changed towards warm-dwelling species at all altitudes. We found no decrease in community variation with respect to temperature niches of species, suggesting that climate warming has not led to more homogenous communities. The different community changes depending on altitude could not be explained by different changes of air temperatures, since during the 16 years between 1995 and 2010, summer temperatures in Switzerland rose by about 0.07°C per year at all altitudes. We discuss that land-use changes or increased disturbances may have prevented alpine plant and butterfly communities from changing towards warm-dwelling species. However, the findings are also consistent with the hypothesis that unlike birds, many alpine plant species in a warming climate could find suitable habitats within just a few metres, due to the highly varied surface of alpine landscapes. Our results may thus support the idea that for plants and butterflies and on a short temporal scale, alpine landscapes are safer places than lowlands in a warming world. PMID:24416144

  1. Numerical experiments on short-term meteorological effects of solar variability. [earth atmosphere model considering solar luminosity effects

    NASA Technical Reports Server (NTRS)

    Somerville, R. C. J.; Hansen, J. E.; Stone, P. H.; Quirk, W. J.; Lacis, A. A.

    1974-01-01

    Set of numerical experiments has been carried out to test the short range sensitivity of a large atmospheric general circulation model to changes in solar constant and ozone amount. On the basis of the results of 12-day integrations with very large variations in these parameters, it is concluded that realistic variations would produce insignificant meteorological effects. Thus any causal relationships between solar variability and weather, for time scales of two weeks or less, will have to rely upon changes in parameters other than solar constant or ozone amounts, or upon mechanisms not yet incorporated in the model.

  2. The effect of short-term intermittent hypoxic exposure on heart rate variability in a sedentary population.

    PubMed

    Lizamore, C A; Kathiravel, Y; Elliott, J; Hellemans, J; Hamlin, M J

    2016-03-01

    While the effects of instantaneous, single-bout exposure to hypoxia have been well researched, little is known about the autonomic response during, or as an adaptation to, repeated intermittent hypoxic exposure (IHE) in a sedentary population. Resting heart rate variability (HRV) and exercise capacity was assessed in 16 participants (8 receiving IHE, [Hyp] and 8 receiving a placebo treatment [C]) before and after a 4-week IHE intervention. Heart rate variability was also measured during an IHE session in the last week of the intervention. Post-intervention, the root mean squared successive difference (rMSSD) increased substantially in Hyp (71.6 ± 52.5%, mean change ± 90% confidence limits) compared to C suggesting an increase in vagal outflow. However, aside from a likely decrease in submaximal exercise heart rate in the Hyp group (-5.0 ± 6.4%) there was little evidence of improved exercise capacity. During the week 4 IHE measurement, HRV decreased during the hypoxic exposure (reduced R-R interval: -7.5 ± 3.2%; and rMSSD: -24.7 ± 17.3%) suggesting a decrease in the relative contribution of vagal activity. In summary, while 4 weeks of IHE is unlikely to improve maximal exercise capacity, it may be a useful means of increasing HRV in people unable to exercise. PMID:27030629

  3. Short-term temperature variability in the Rose Garden hydrothermal vent field: an unstable deep-sea environment

    NASA Astrophysics Data System (ADS)

    Johnson, Kenneth S.; Childress, James J.; Beehler, Carl L.

    1988-10-01

    Temperature was measured within the animal communities of the Rose Garden hydrothermal vent field with three thermistors that were left in place for a period of 72 h. The highest mean temperature (5.54°C) was measured at a thermistor placed in the central clump of vestimentiferan worms, while the lowest mean value (2.26°C) was recorded over the basaltic substrate. The temperature of the ambient water in the field was 2.07°C. The site with the highest temperature was characterized by extreme variability in the temperature, with minimum values of 2.16°C and maximum values of 14.81°C. The temperature fluctuated over all of the time scales studied from 1 s to 72 h. There was no clear periodicity to the temperature fluctuations, however. These temperature fluctuations must have significant impacts on adaptations, by the animals of the vent community. In fact, the variability in temperature may be more important to the community than the mean temperature value to which they are exposed.

  4. Short-term under-ice variability of prokaryotic plankton communities in coastal Antarctic waters (Cape Hallett, Ross Sea)

    NASA Astrophysics Data System (ADS)

    Celussi, Mauro; Paoli, Alessandro; Crevatin, Erica; Bergamasco, Andrea; Margiotta, Francesca; Saggiomo, Vincenzo; Umani, Serena Fonda; Del Negro, Paola

    2009-03-01

    During the 2006 Italian Antarctic expedition a diel sampling was performed close to Cape Hallett (Ross Sea) during the Austral summer. Under-ice seawater samples (˜4 m) were collected every 2 h for 28 h in order to estimate prokaryotic processes' variability and community structure dynamics. Prokaryotic and viral abundances, exoenzymatic activities (β-glucosidase, chitinase, lipase, alkaline phosphatase and leucine aminopeptidase), prokaryotic carbon production ( 3H-leucine incorporation) and community structure (Denaturing Gradient Gel Electrophoresis - DGGE fingerprints) were analysed. Results showed that the diel variability of the prokaryotic activity followed a variation in salinity, probably as a consequence of the periodical thawing of sea ice (driven by solar radiation and air temperature cycles), while negligible variation in viral and prokaryotic abundances occurred. The Bacterial and Archaeal community structures underwent an Operational Taxonomic Units (OTUs) temporal shift from the beginning to the end of the sampling, while Flavobacteria-specific primers highlighted high variations in this group possibly related to sea ice melting and substrate release.

  5. Projected Applications of a "Climate in a Box" Computing System at the NASA Short-Term Prediction Research and Transition (SPoRT) Center

    NASA Technical Reports Server (NTRS)

    Jedlovec, Gary J.; Molthan, Andrew L.; Zavodsky, Bradley; Case, Jonathan L.; LaFontaine, Frank J.

    2010-01-01

    The NASA Short-term Prediction Research and Transition (SPoRT) Center focuses on the transition of unique observations and research capabilities to the operational weather community, with a goal of improving short-term forecasts on a regional scale. Advances in research computing have lead to "Climate in a Box" systems, with hardware configurations capable of producing high resolution, near real-time weather forecasts, but with footprints, power, and cooling requirements that are comparable to desktop systems. The SPoRT Center has developed several capabilities for incorporating unique NASA research capabilities and observations with real-time weather forecasts. Planned utilization includes the development of a fully-cycled data assimilation system used to drive 36-48 hour forecasts produced by the NASA Unified version of the Weather Research and Forecasting (WRF) model (NU-WRF). The horsepower provided by the "Climate in a Box" system is expected to facilitate the assimilation of vertical profiles of temperature and moisture provided by the Atmospheric Infrared Sounder (AIRS) aboard the NASA Aqua satellite. In addition, the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard NASA s Aqua and Terra satellites provide high-resolution sea surface temperatures and vegetation characteristics. The development of MODIS normalized difference vegetation index (NVDI) composites for use within the NASA Land Information System (LIS) will assist in the characterization of vegetation, and subsequently the surface albedo and processes related to soil moisture. Through application of satellite simulators, NASA satellite instruments can be used to examine forecast model errors in cloud cover and other characteristics. Through the aforementioned application of the "Climate in a Box" system and NU-WRF capabilities, an end goal is the establishment of a real-time forecast system that fully integrates modeling and analysis capabilities developed within the NASA SPo

  6. Projected Applications of a ``Climate in a Box'' Computing System at the NASA Short-term Prediction Research and Transition (SPoRT) Center

    NASA Astrophysics Data System (ADS)

    Jedlovec, G.; Molthan, A.; Zavodsky, B.; Case, J.; Lafontaine, F.

    2010-12-01

    The NASA Short-term Prediction Research and Transition (SPoRT) Center focuses on the transition of unique observations and research capabilities to the operational weather community, with a goal of improving short-term forecasts on a regional scale. Advances in research computing have lead to “Climate in a Box” systems, with hardware configurations capable of producing high resolution, near real-time weather forecasts, but with footprints, power, and cooling requirements that are comparable to desktop systems. The SPoRT Center has developed several capabilities for incorporating unique NASA research capabilities and observations with real-time weather forecasts. Planned utilization includes the development of a fully-cycled data assimilation system used to drive 36-48 hour forecasts produced by the NASA Unified version of the Weather Research and Forecasting (WRF) model (NU-WRF). The horsepower provided by the “Climate in a Box” system is expected to facilitate the assimilation of vertical profiles of temperature and moisture provided by the Atmospheric Infrared Sounder (AIRS) aboard the NASA Aqua satellite. In addition, the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard NASA’s Aqua and Terra satellites provide high-resolution sea surface temperatures and vegetation characteristics. The development of MODIS normalized difference vegetation index (NVDI) composites for use within the NASA Land Information System (LIS) will assist in the characterization of vegetation, and subsequently the surface albedo and processes related to soil moisture. Through application of satellite simulators, NASA satellite instruments can be used to examine forecast model errors in cloud cover and other characteristics. Through the aforementioned application of the “Climate in a Box” system and NU-WRF capabilities, an end goal is the establishment of a real-time forecast system that fully integrates modeling and analysis capabilities developed

  7. Winchester/Camberley Homes New Construction Test House Design, Construction, and Short-Term Testing in a Mixed-Humid Climate

    SciTech Connect

    Mallav, D.; Wiehagen, J.; Wood, A.

    2012-10-01

    The NAHB Research Center partnered with production builder Winchester/Camberley Homes to build a DOE Building America New Construction Test House (NCTH). This single family, detached house, located in the mixed-humid climate zone of Silver Spring, MD, was completed in June 2011. The primary goal for this house was to improve energy efficiency by 30% over the Building America B10 benchmark by developing and implementing an optimized energy solutions package design that could be cost effectively and reliably constructed on a production basis using quality management practices. The intent of this report is to outline the features of this house, discuss the implementation of the energy efficient design, and report on short-term testing results. During the interactive design process of this project, numerous iterations of the framing, air sealing, insulation, and space conditioning systems were evaluated for energy performance, cost, and practical implementation. The final design featured numerous advanced framing techniques, high levels of insulation, and the HVAC system entirely within conditioned space. Short-term testing confirmed a very tight thermal envelope and efficient and effective heating and cooling. In addition, relevant heating, cooling, humidity, energy, and wall cavity moisture data will be collected and presented in a future long-term report.

  8. Using Ensemble Short-Term Initialized Coupled NASA GEOS5 Climate Model Integrations to Study Convective Bias Growth

    NASA Technical Reports Server (NTRS)

    Cohen, Charlie; Robertson, Franklin; Molod, Andrea

    2014-01-01

    The representation of convective processes, particularly deep convection in the tropics, remains a persistent problem in climate models. In fact structural biases in the distribution of tropical rainfall in the CMIP5 models is hardly different than that of the CMIP3 versions. Given that regional climate change at higher latitudes is sensitive to the configuration of tropical forcing, this persistent bias is a major issue for the credibility of climate change projections. In this study we use model output from integrations of the NASA Global Earth Observing System Five (GEOS5) climate modeling system to study the evolution of biases in the location and intensity of convective processes. We take advantage of a series of hindcast experiments done in support of the US North American Multi-Model Ensemble (NMME) initiative. For these experiments a nine-month forecast using a coupled model configuration is made approximately every five days over the past 30 years. Each forecast is started with an updated analysis of the ocean, atmosphere and land states. For a given calendar month we have approximately 180 forecasts with daily means of various quantities. These forecasts can be averaged to essentially remove "weather scales" and highlight systematic errors as they evolve. Our primary question is to ask how the spatial structure of daily mean precipitation over the tropics evolves from the initial state and what physical processes are involved. Errors in parameterized convection, various water and energy fluxes and the divergent circulation are found to set up on fast time scales (order five days) compared to errors in the ocean, although SST changes can be non-negligible over that time. For the month of June the difference between forecast day five versus day zero precipitation looks quite similar to the difference between the June precipitation climatology and that from the Global Precipitation Climatology Project (GPCP). We focus much of our analysis on the influence of

  9. Short-term variability and mass loss in Be stars. I. BRITE satellite photometry of η and μ Centauri

    NASA Astrophysics Data System (ADS)

    Baade, D.; Rivinius, Th.; Pigulski, A.; Carciofi, A. C.; Martayan, Ch.; Moffat, A. F. J.; Wade, G. A.; Weiss, W. W.; Grunhut, J.; Handler, G.; Kuschnig, R.; Mehner, A.; Pablo, H.; Popowicz, A.; Rucinski, S.; Whittaker, G.

    2016-04-01

    Context. Empirical evidence for the involvement of nonradial pulsations (NRPs) in the mass loss from Be stars ranges from (i) a singular case (μ Cen) of repetitive mass ejections triggered by multi-mode beating to (ii) several photometric reports about enormous numbers of pulsation modes that suddenly appear during outbursts and on to (iii) effective single-mode pulsators. Aims: The purpose of this study is to develop a more detailed empirical description of the star-to-disk mass transfer and to check the hypothesis that spates of transient nonradial pulsation modes accompany and even drive mass-loss episodes. Methods: The BRITE Constellation of nanosatellites was used to obtain mmag photometry of the Be stars η and μ Cen. Results: In the low-inclination star μ Cen, light pollution by variable amounts of near-stellar matter prevented any new insights into the variability and other properties of the central star. In the equator-on star η Cen, BRITE photometry and Heros echelle spectroscopy from the 1990s reveal an intricate clockwork of star-disk interactions. The mass transfer is modulated with the frequency difference of two NRP modes and an amplitude three times as large as the amplitude sum of the two NRP modes. This process feeds a high-amplitude circumstellar activity running with the incoherent and slightly lower so-called Štefl frequency. The mass-loss-modulation cycles are tightly coupled to variations in the value of the Štefl frequency and in its amplitude, albeit with strongly drifting phase differences. Conclusions: The observations are well described by the decomposition of the mass loss into a pulsation-related engine in the star and a viscosity-dominated engine in the circumstellar disk. Arguments are developed that large-scale gas-circulation flows occur at the interface. The propagation rates of these eddies manifest themselves as Štefl frequencies. Bursts in power spectra during mass-loss events can be understood as the noise inherent to

  10. Can short-term heart rate variability be used to monitor fentanyl-midazolam induced changes in ANS preceding respiratory depression?

    PubMed

    Smith, Anne-Louise; Owen, Harry; Reynolds, Karen J

    2015-06-01

    Opioids have an occasional but high-risk side effect of respiratory depression. The detection of critical respiratory depression usually occurs after the event. Earlier detection would be beneficial in preventing increased morbidity and mortality of 0.01 % patients receiving analgesic opioids. Airway patency during inspiration requires vagal modulation. Regulation of the cardiovascular and respiratory centres may be coupled with a central mechanism that is indirectly measurable with heart rate variability (HRV). While opioids tend to increase parasympathetic tone, a decrease in airway stability could be due to a decrease in respiratory parasympathetic activity. Sympathetic arousal generated by apneic events may separately be recognised with short-term HRV. This pilot observational study examined the dynamic sympathovagal changes during fentanyl-midazolam induced respiratory depression on 10 subjects scheduled for minor surgery. A selection of HRV indices, able to work over sub-minute periods on non-stationary signals, were applied including a range of less common indices. Three analyses tested the effects: post-fentanyl, preceding the first central depression, and preceding obstruction of the upper airway. Statistical significance was assessed with overlap of bootstrap percentile confidence intervals for the median. A decrease in total variability, Lomb Total using the Lomb-Scargle method, is a positive finding for short-term HRV use in this study. No significant change before critical respiratory events was observed in traditional, spectral power, respiratory or other indices. One index, PolVar20, indicated a burst of sympathetic activity preceding respiratory depression similar to sleep apnoea arousals that restore airway patency. Before its usefulness in early detection of airway tone can be determined, PolVar20 requires further work: a statistical method for highly skewed distributions, auto adjustment for baseline variability, and detecting a range of

  11. Short-term pulse rate variability is better characterized by functional near-infrared spectroscopy than by photoplethysmography.

    PubMed

    Holper, Lisa; Seifritz, Erich; Scholkmann, Felix

    2016-09-01

    Pulse rate variability (PRV) can be extracted from functional near-infrared spectroscopy (fNIRS) (PRV(NIRS)) and photoplethysmography (PPG) (PRV(PPG)) signals. The present study compared the accuracy of simultaneously acquired PRV(NIRS) and PRV(PPG), and evaluated their different characterizations of the sympathetic (SNS) and parasympathetic (PSNS) autonomous nervous system activity. Ten healthy subjects were recorded during resting-state (RS) and respiratory challenges in two temperature conditions, i.e., room temperature (23°C) and cold temperature (4°C). PRV(NIRS) was recorded based on fNIRS measurement on the head, whereas PRV(PPG) was determined based on PPG measured at the finger. Accuracy between PRV(NIRS) and PRV(PPG), as assessed by cross-covariance and cross-sample entropy, demonstrated a high degree of correlation (r > 0.9), which was significantly reduced by respiration and cold temperature. Characterization of SNS and PSNS using frequency-domain, time-domain, and nonlinear methods showed that PRV(NIRS) provided significantly better information on increasing PSNS activity in response to respiration and cold temperature than PRV(PPG). The findings show that PRV(NIRS) may outperform PRV(PPG) under conditions in which respiration and temperature changes are present, and may, therefore, be advantageous in research and clinical settings, especially if characterization of the autonomous nervous system is desired. PMID:27185106

  12. Short-term variability in euphotic zone biogeochemistry and primary productivity at Station ALOHA: A case study of summer 2012

    NASA Astrophysics Data System (ADS)

    Wilson, Samuel T.; Barone, Benedetto; Ascani, Francois; Bidigare, Robert R.; Church, Matthew J.; Valle, Daniela A.; Dyhrman, Sonya T.; Ferrón, Sara; Fitzsimmons, Jessica N.; Juranek, Laurie W.; Kolber, Zbigniew S.; Letelier, Ricardo M.; Martínez-García, Sandra; Nicholson, David P.; Richards, Kelvin J.; Rii, Yoshimi M.; Rouco, Mónica; Viviani, Donn A.; White, Angelicque E.; Zehr, Jonathan P.; Karl, David M.

    2015-08-01

    Time-series observations are critical to understand the structure, function, and dynamics of marine ecosystems. The Hawaii Ocean Time-series program has maintained near-monthly sampling at Station ALOHA (22°45'N, 158°00'W) in the oligotrophic North Pacific Subtropical Gyre (NPSG) since 1988 and has identified ecosystem variability over seasonal to interannual timescales. To further extend the temporal resolution of these near-monthly time-series observations, an extensive field campaign was conducted during July-September 2012 at Station ALOHA with near-daily sampling of upper water-column biogeochemistry, phytoplankton abundance, and activity. The resulting data set provided biogeochemical measurements at high temporal resolution and documents two important events at Station ALOHA: (1) a prolonged period of low productivity when net community production in the mixed layer shifted to a net heterotrophic state and (2) detection of a distinct sea-surface salinity minimum feature which was prominent in the upper water column (0-50 m) for a period of approximately 30 days. The shipboard observations during July-September 2012 were supplemented with in situ measurements provided by Seagliders, profiling floats, and remote satellite observations that together revealed the extent of the low productivity and the sea-surface salinity minimum feature in the NPSG.

  13. Impact of length of stay after coronary bypass surgery on short-term readmission rate: An instrumental variable analysis

    PubMed Central

    Li, Yue; Cai, Xueya; Mukamel, Dana B.; Cram, Peter

    2012-01-01

    Objective To determine the effect of postoperative length of stay on 30-day readmission after coronary artery bypass surgery. Data Sources/Study Setting We analyzed a final database consisting of Medicare claims of a cohort (N=157,070) of all fee-for-service beneficiaries undergoing bypass surgery during 2007-2008, the American Hospital Association annual survey file, and the rural urban commuting area file. Study Design We regressed the probability of 30-day readmission on postoperative length of stay using (1) a (naïve) logit model that controlled for observed patient and hospital covariates only; and (2) a residual inclusion instrumental variable (IV) logit model that further controlled for unobserved confounding. The IV was defined using a measure of the hospital’s risk-adjusted length of stay for patients admitted for gastrointestinal hemorrhage. Principal Findings The naïve logit model predicted that a one-day reduction in median post-operative length of stay (i.e. from a median of 6 days to 5 days) lowered the 30-day readmission rate by 2 percentage points. The IV model predicted that a one-day reduction in median post-operative length of stay increased 30-day readmission rate by 3 percentage points. Conclusions The findings indicate that a reduction in postoperative length of stay is associated with an increased risk for 30-day readmission among Medicare patients undergoing bypass surgery, after both observed and unobserved confounding effects are corrected. PMID:23032357

  14. Short-term temporal and spatial variability of soil hydrophobicity in an abandoned agriculture field in Lithuania

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Burguet, Maria; Cerdà, Artemi

    2013-04-01

    Soil water repellency (SWR) is a natural property of soils. Among other factors, SWR depends on soil moisture, mineralogy, texture, pH, organic matter, aggregate stability, fungal and microbiological activity and plant cover. It has implications on plant growth, superficial and subsurface hydrology and soil erosion. It is well known that SWR is temporarily, increasing when soils are dry and decreasing when moist. In agriculture, soil micro-topography is very heterogeneous with implications on surface water distribution and wettability. Normally, SWR studies are focused on large interval time (e.g, monthly or seasonally). The objective of this work is the study of SWR in a temporal scale and its variability in an abandoned agriculture field in Lithuania. An experimental plot with 21 m2 (07x03 m) was designed in a flat area. Inside this plot SWR was measured in the field, placing three droplets of water on the soil surface and counting the time that takes to infiltrate. A total of 105 sampling points were measured per sampling period. Soil water repellency was measured after a period of 14 days without rainfall and in the seven consequent weeks (one measurement per week between 28th May and 07th of July 2012). The results showed that in this small plot, SWR was observed in the first (May 28), third and fourth measurements (08th of June and 16th). It was observed an increasing of the percentage of hydrophobic points (Water Drop Penetration Test ≥5 seconds) between the first and the fourth measurement, decreasing thereafter. Significant differences of SWR were observed among all periods (F=78.32, p<0.0001). The coefficient of variation (CV%) changed strikingly, 361.10 % (8th of May), 151.78 % (01st of June), 83.77% (08th of June), 125.87% (16th of June), 0.45 (22nd of June), 121%(31st of June) and 67.13% (7th of July). The correlation between the mean SWR and the CV% is 0.75, p<0.05. The changes were attributed to different soil moisture conditions. The differences

  15. Short-Term Chromospheric Variability in alpha Tauri (K5 III): Results from IUE Time Series Observations

    NASA Technical Reports Server (NTRS)

    Cuntz, Manfred; Deeney, Bryan D.; Brown, Alexander; Stencel, Robert E.

    1996-01-01

    We evaluate time series observations of chromospheric lines (Mg II, Mg I, and C II) for the K giant alpha Tau obtained using the IUE LWP camera at high dispersion. These observations cover a time span of about 2 weeks in 1994 February-March and were designed to resolve variations occurring within hours, days, and weeks. We consider the observational results in relation to theoretical acoustic heating models, motivated by the fact that alpha Tau may exhibit a basal (i.e., minimum) level of chromospheric activity. The data reveal flux variations between the extremes of 8% in Mg II h+k and 15% in each emission component. These variations occur on timescales as short as 8 hr but not on timescales longer than approx.3 days. For the h and k components, flux variations occurring on a timescale as short as 1.5 hr are also found. These changes are often not correlated (and are sometimes even anticorrelated), leading to remarkable differences in the h/k ratios. We argue that these results are consistent with the presence of strong acoustic shocks, which can lead to variable Mg II line emission when only a small number of strong shocks are propagating through the atmosphere. We deduce the electron density in the C II lambda 2325 line formation region to be log(base e) of N. approx. equals 9.0, in agreement with previous studies. Our data provide evidence that the Mg II basal flux limit for K giants might be a factor of 4 higher than suggested by Rutten et al.

  16. Short-Term Exposure to Ozone Does Not Impair Vascular Function or Affect Heart Rate Variability in Healthy Young Men

    PubMed Central

    Barath, Stefan; Langrish, Jeremy P.; Blomberg, Anders

    2013-01-01

    Air pollution exposure is associated with cardiovascular morbidity and mortality, yet the role of individual pollutants remains unclear. In particular, there is uncertainty regarding the acute effect of ozone exposure on cardiovascular disease. In these studies, we aimed to determine the effect of ozone exposure on vascular function, fibrinolysis, and the autonomic regulation of the heart. Thirty-six healthy men were exposed to ozone (300 ppb) and filtered air for 75min on two occasions in randomized double-blind crossover studies. Bilateral forearm blood flow (FBF) was measured using forearm venous occlusion plethysmography before and during intra-arterial infusions of vasodilators 2–4 and 6–8h after each exposure. Heart rhythm and heart rate variability (HRV) were monitored during and 24h after exposure. Compared with filtered air, ozone exposure did not alter heart rate, blood pressure, or resting FBF at either 2 or 6h. There was a dose-dependent increase in FBF with all vasodilators that was similar after both exposures at 2–4h. Ozone exposure did not impair vasomotor or fibrinolytic function at 6–8h but rather increased vasodilatation to acetylcholine (p = .015) and sodium nitroprusside (p = .005). Ozone did not affect measures of HRV during or after the exposure. Our findings do not support a direct rapid effect of ozone on vascular function or cardiac autonomic control although we cannot exclude an effect of chronic exposure or an interaction between ozone and alternative air pollutants that may be responsible for the adverse cardiovascular health effects attributed to ozone. PMID:23872581

  17. Short-term sandbar variability based on video imagery: Comparison between Time-Average and Time-Variance techniques

    USGS Publications Warehouse

    Guedes, R.M.C.; Calliari, L.J.; Holland, K.T.; Plant, N.G.; Pereira, P.S.; Alves, F.N.A.

    2011-01-01

    Time-exposure intensity (averaged) images are commonly used to locate the nearshore sandbar position (xb), based on the cross-shore locations of maximum pixel intensity (xi) of the bright bands in the images. It is not known, however, how the breaking patterns seen in Variance images (i.e. those created through standard deviation of pixel intensity over time) are related to the sandbar locations. We investigated the suitability of both Time-exposure and Variance images for sandbar detection within a multiple bar system on the southern coast of Brazil, and verified the relation between wave breaking patterns, observed as bands of high intensity in these images and cross-shore profiles of modeled wave energy dissipation (xD). Not only is Time-exposure maximum pixel intensity location (xi-Ti) well related to xb, but also to the maximum pixel intensity location of Variance images (xi-Va), although the latter was typically located 15m offshore of the former. In addition, xi-Va was observed to be better associated with xD even though xi-Ti is commonly assumed as maximum wave energy dissipation. Significant wave height (Hs) and water level (??) were observed to affect the two types of images in a similar way, with an increase in both Hs and ?? resulting in xi shifting offshore. This ??-induced xi variability has an opposite behavior to what is described in the literature, and is likely an indirect effect of higher waves breaking farther offshore during periods of storm surges. Multiple regression models performed on xi, Hs and ?? allowed the reduction of the residual errors between xb and xi, yielding accurate estimates with most residuals less than 10m. Additionally, it was found that the sandbar position was best estimated using xi-Ti (xi-Va) when xb was located shoreward (seaward) of its mean position, for both the first and the second bar. Although it is unknown whether this is an indirect hydrodynamic effect or is indeed related to the morphology, we found that this

  18. Short-term variability during an anchor station study in the southern Benguela upwelling system: Chemical and physical oceanography

    NASA Astrophysics Data System (ADS)

    Bailey, G. W.; Chapman, P.

    During March and April 1987, an anchor station experiment was conducted in 45m water depth in St Helena Bay (32°30‧S) on the west coast of South Africa, “downstream” of a major upwelling centre at Cape Columbine. Temperature, salinity, oxygen, chlorophyll and nutrient concentrations were measured at seven depths down to 43m at four-hourly intervals over a 30 day period. These measurements were accompanied by current metering and weather station observations. Additional biological measurements of primary and secondary productivity were also carried out (see other papers in this suite). The period of the anchor station covered one major upwelling/decay cycle during the first fortnight of the experiment, followed by a second upwelling-favourable period. Throughout the experiment, stratification was observed in all parameters. The physical oceanography data suggested that the gyral circulation in the area tends to trap organic matter on the shelf as part of a two-layer system. Coastally-trapped internal waves and tidal periodicity control the relative importance of surface and bottom layers, which show considerable shear across the interface, because of the difference in cross-shelf circulation in the two layers. Despite sudden changes in bottom current velocities, little change was found in the distribution of chemical parameters below the thermocline, suggesting that relatively little net advection occurs into the bay, in contrast to the steeper slope regime. Chemical parameters showed consistent variability over the inertial period (22.5h). The inverse relationship between nitrate, phosphate or silicate and dissolved oxygen confirmed the importance of nutrient regeneration in the bottom mixed layer (BML), although considerable differences existed between nitrate and the other two nutrients. Rates of uptake during phytoplankton growth and replenishment during upwelling suggests that minimum upwelling rates in the Cape Columbine area were of the order of 0

  19. Short-term memory

    NASA Astrophysics Data System (ADS)

    Toulouse, G.

    This is a rather bold attempt to bridge the gap between neuron structure and psychological data. We try to answer the question: Is there a relation between the neuronal connectivity in the human cortex (around 5,000) and the short-term memory capacity (7±2)? Our starting point is the Hopfield model (Hopfield 1982), presented in this volume by D.J. Amit.

  20. Effects of long- and short-term management on the functional structure of meadows through species turnover and intraspecific trait variability.

    PubMed

    Volf, Martin; Redmond, Conor; Albert, Ágnes J; Le Bagousse-Pinguet, Yoann; Biella, Paolo; Götzenberger, Lars; Hrázský, Záboj; Janeček, Štěpán; Klimešová, Jitka; Lepš, Jan; Šebelíková, Lenka; Vlasatá, Tereza; de Bello, Francesco

    2016-04-01

    The functional structures of communities respond to environmental changes by both species replacement (turnover) and within-species variation (intraspecific trait variability; ITV). Evidence is lacking on the relative importance of these two components, particularly in response to both short- and long-term environmental disturbance. We hypothesized that such short- and long-term perturbations would induce changes in community functional structure primarily via ITV and turnover, respectively. To test this we applied an experimental design across long-term mown and abandoned meadows, with each plot containing a further level of short-term management treatments: mowing, grazing and abandonment. Within each plot, species composition and trait values [height, shoot biomass, and specific leaf area (SLA)] were recorded on up to five individuals per species. Positive covariations between the contribution of species turnover and ITV occurred for height and shoot biomass in response to both short- and long-term management, indicating that species turnover and intraspecific adjustments selected for similar trait values. Positive covariations also occurred for SLA, but only in response to long-term management. The contributions of turnover and ITV changed depending on both the trait and management trajectory. As expected, communities responded to short-term disturbances mostly through changes in intraspecific trait variability, particularly for height and biomass. Interestingly, for SLA they responded to long-term disturbances by both species turnover and intraspecific adjustments. These findings highlight the importance of both ITV and species turnover in adjusting grassland functional trait response to environmental perturbation, and show that the response is trait specific and affected by disturbance regime history. PMID:26837384

  1. Short-term beat-to-beat variability of the QT interval is increased and correlates with parameters of left ventricular hypertrophy in patients with hypertrophic cardiomyopathy.

    PubMed

    Orosz, Andrea; Baczkó, István; Nagy, Viktória; Gavallér, Henriette; Csanády, Miklós; Forster, Tamás; Papp, Julius Gy; Varró, András; Lengyel, Csaba; Sepp, Róbert

    2015-09-01

    Stratification models for the prediction of sudden cardiac death (SCD) are inappropriate in patients with hypertrophic cardiomyopathy (HCM). We investigated conventional electrocardiogram (ECG) repolarization parameters and the beat-to-beat short-term QT interval variability (QT-STV), a new parameter of proarrhythmic risk, in 37 patients with HCM (21 males, average age 48 ± 15 years). Resting ECGs were recorded for 5 min and the frequency corrected QT interval (QTc), QT dispersion (QTd), beat-to-beat short-term variability of QT interval (QT-STV), and the duration of terminal part of T waves (Tpeak-Tend) were calculated. While all repolarization parameters were significantly increased in patients with HCM compared with the controls (QTc, 488 ± 61 vs. 434 ± 23 ms, p < 0.0001; QT-STV, 4.5 ± 2 vs. 3.2 ± 1 ms, p = 0.0002; Tpeak-Tend duration, 107 ± 27 vs. 91 ± 10 ms, p = 0.0015; QTd, 47 ± 17 vs. 34 ± 9 ms, p = 0.0002), QT-STV had the highest relative increase (+41%). QT-STV also showed the best correlation with indices of left ventricular (LV) hypertrophy, i.e., maximal LV wall thickness normalized for body surface area (BSA; r = 0.461, p = 0.004) or LV mass (determined by cardiac magnetic resonance imaging) normalized for BSA (r = 0.455, p = 0.015). In summary, beat-to-beat QT-STV showed the most marked increase in patients with HCM and may represent a novel marker that merits further testing for increased SCD risk in HCM. PMID:26313025

  2. Short-term variability of the Sun-Earth system: an overview of progress made during the CAWSES-II period

    NASA Astrophysics Data System (ADS)

    Gopalswamy, Nat; Tsurutani, Bruce; Yan, Yihua

    2015-12-01

    This paper presents an overview of results obtained during the CAWSES-II period on the short-term variability of the Sun and how it affects the near-Earth space environment. CAWSES-II was planned to examine the behavior of the solar-terrestrial system as the solar activity climbed to its maximum phase in solar cycle 24. After a deep minimum following cycle 23, the Sun climbed to a very weak maximum in terms of the sunspot number in cycle 24 (MiniMax24), so many of the results presented here refer to this weak activity in comparison with cycle 23. The short-term variability that has immediate consequence to Earth and geospace manifests as solar eruptions from closed-field regions and high-speed streams from coronal holes. Both electromagnetic (flares) and mass emissions (coronal mass ejections - CMEs) are involved in solar eruptions, while coronal holes result in high-speed streams that collide with slow wind forming the so-called corotating interaction regions (CIRs). Fast CMEs affect Earth via leading shocks accelerating energetic particles and creating large geomagnetic storms. CIRs and their trailing high-speed streams (HSSs), on the other hand, are responsible for recurrent small geomagnetic storms and extended days of auroral zone activity, respectively. The latter leads to the acceleration of relativistic magnetospheric `killer' electrons. One of the major consequences of the weak solar activity is the altered physical state of the heliosphere that has serious implications for the shock-driving and storm-causing properties of CMEs. Finally, a discussion is presented on extreme space weather events prompted by the 23 July 2012 super storm event that occurred on the backside of the Sun. Many of these studies were enabled by the simultaneous availability of remote sensing and in situ observations from multiple vantage points with respect to the Sun-Earth line.

  3. Climate Variability Program

    NASA Technical Reports Server (NTRS)

    Halpern, David (Editor)

    1999-01-01

    The Annual Report of the Climate Variability Program briefly describes research activities of 40 Principal Investigators who are funded by NASA's Earth Science Enterprise Research Division. The report is focused on the year 1998. Utilization of satellite observations is a singularity of research on climate science and technology at JPL. Research at JPL has two foci: generate new knowledge and develop new technology.

  4. Validity and Usefulness of `Wearable Blood Pressure Sensing' for Detection of Inappropriate Short-Term Blood Pressure Variability in the Elderly

    NASA Astrophysics Data System (ADS)

    Iijima, Katsuya; Kameyama, Yumi; Akishita, Masahiro; Ouchi, Yasuyoshi; Yanagimoto, Shintaro; Imai, Yasushi; Yahagi, Naoki; Lopez, Guillaume; Shuzo, Masaki; Yamada, Ichiro

    An increase in short-term blood pressure (BP) variability is a characteristic feature in the elderly. It makes the management of hemodynamics more difficult, because it is frequently seen disturbed baro-reflex function and increased arterial stiffness, leading to isolated systolic hypertension. Large BP variability aggravates hypertensive target organ damage and is an independent risk factor for the cardiovascular (CV) events in elderly hypertensive patients. Therefore, appropriate control in BP is indispensable to manage lifestyle-related diseases and to prevent subsequent CV events. In addition, accumulating recent reports show that excessive BP variability is also associated with a decline in cognitive function and fall in the elderly. In the clinical settings, we usually evaluate their health condition, mainly with single point BP measurement using cuff inflation. However, unfortunately we are not able to find the close changes in BP by the traditional way. Here, we can show our advantageous approach of continuous BP monitoring using newly developing device `wearable BP sensing' without a cuff stress in the elderly. The new device could reflect systolic BP and its detailed changes, in consistent with cuff-based BP measurement. Our new challenge suggests new possibility of its clinical application with high accuracy.

  5. Short-term variability in respiratory impedance and effect of deep breath in asthmatic and healthy subjects with airway smooth muscle activation and unloading.

    PubMed

    Gobbi, Alessandro; Pellegrino, Riccardo; Gulotta, Carlo; Antonelli, Andrea; Pompilio, Pasquale; Crimi, Claudia; Torchio, Roberto; Dutto, Luca; Parola, Paolo; Dellacà, Raffaele L; Brusasco, Vito

    2013-09-01

    Inspiratory resistance (RINSP) and reactance (XINSP) were measured for 7 min at 5 Hz in 10 subjects with mild asymptomatic asthma and 9 healthy subjects to assess the effects of airway smooth muscle (ASM) activation by methacholine (MCh) and unloading by chest wall strapping (CWS) on the variability of lung function and the effects of deep inspiration (DI). Subjects were studied at control conditions, after MCh, with CWS, and after MCh with CWS. In all experimental conditions XINSP was significantly more negative in subjects with asthma than in healthy subjects, suggesting greater inhomogeneity in the former. However, the variability in both RINSP and XINSP was increased by either ASM activation or CWS, without significant difference between groups. DI significantly reversed MCh-induced changes in RINSP both in subjects with asthma and healthy subjects, but XINSP in the former only. This effect was impaired by CWS more in subjects with asthma than in healthy subjects. The velocity of RINSP and XINSP recovery after DI was faster in subjects with asthma than healthy subjects. In conclusion, these results support the opinion that the short-term variability in respiratory impedance is related to ASM tone or operating length, rather than to the disease. Nevertheless, ASM in individuals with asthma differs from that in healthy individuals in an increased velocity of shortening and a reduced sensitivity to mechanical stress when strain is reduced. PMID:23766502

  6. Climate-induced variations in lake levels: A mechanism for short-term sea level change during non-glacial times

    SciTech Connect

    Jacobs, D. ); Sahagian, D. . Dept of Geological Sciences)

    1992-01-01

    Variations in insolation due to periodic orbital parameters can cause climatic changes and associated variations in the intensity of monsoonal circulation. This can lead to significant variations in the levels of internally draining lakes on timescales of 10,000 to 100,000 years in regions affected by the monsoon (20,000 years for orbital precession). These variations may be responsible for small scale (few meters) eustatic sea level changes in an ice-free Earth, and may contribute to sea level changes in the presence of ice as well. The authors have estimated the volume of empty present lake basins in the regions of Asia and North Africa influenced by the monsoon. The surface water volume alone of these basins is equivalent to a two meter difference in sea level, but is considerably augmented by groundwater associated with an increase in lake level. The lake variation mechanism for sea level change has its basis in the Quaternary record of climate change and associated explanatory models. However, the argument also applies to earlier, non-glacial periods of geologic time. Clear evidence for the presence of ice in the Triassic is lacking. However, there is evidence for short-term periodic fluctuations of lake levels as well as sea level during that time. These sea level changes, as well as those in the Devonian, Jurassic, and Cretaceous, may be driven by periodic fluctuation in lacustrine and groundwater storage resulting from orbitally forced changes in monsoon intensity, even in the absence of significant glacial ice.

  7. Short-term radio variability and parsec-scale structure in A gamma-ray narrow-line Seyfert 1 galaxy 1H 0323+342

    SciTech Connect

    Wajima, Kiyoaki; Fujisawa, Kenta; Hayashida, Masaaki; Isobe, Naoki; Ishida, Takafumi; Yonekura, Yoshinori

    2014-02-01

    We made simultaneous single-dish and very long baseline interferometer (VLBI) observations of a narrow-line Seyfert 1 galaxy 1H 323+342, showing gamma-ray activity revealed by Fermi/Large Area Telescope observations. We found significant variation of the total flux density at 8 GHz on the timescale of one month by the single-dish monitoring. The total flux density varied by 5.5% in 32 days, which is comparable to the gamma-ray variability timescale, corresponding to the variability brightness temperature of 7.0 × 10{sup 11} K. The source consists of central and southeastern components on the parsec (pc) scale. Only the flux of the central component decreased in the same way as the total flux density, indicating that the short-term radio variability, and probably the gamma-ray-emitting region, is associated with this component. From the VLBI observations, we obtained brightness temperatures of greater than (5.2 ± 0.3) × 10{sup 10} K and derived an equipartition Doppler factor of greater than 1.7, a variability Doppler factor of 2.2, and an 8 GHz radio power of 10{sup 24.6} W Hz{sup –1}. Combining them, we conclude that acceleration of radio jets and creation of high-energy particles are ongoing in the central engine and that the apparent very radio-loud feature of the source is due to the Doppler boosting effect, resulting in the intrinsic radio loudness being an order of magnitude smaller than the observed values. We also conclude that the pc-scale jet represents recurrent activity from the spectral fitting and the estimated kinematic age of pc- and kpc-scale extended components with different position angles.

  8. Short term spatio-temporal variability of soil water-extractable calcium and magnesium after a low severity grassland fire in Lithuania.

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Martin, David

    2014-05-01

    Fire has important impacts on soil nutrient spatio-temporal distribution (Outeiro et al., 2008). This impact depends on fire severity, topography of the burned area, type of soil and vegetation affected, and the meteorological conditions post-fire. Fire produces a complex mosaic of impacts in soil that can be extremely variable at small plot scale in the space and time. In order to assess and map such a heterogeneous distribution, the test of interpolation methods is fundamental to identify the best estimator and to have a better understanding of soil nutrients spatial distribution. The objective of this work is to identify the short-term spatial variability of water-extractable calcium and magnesium after a low severity grassland fire. The studied area is located near Vilnius (Lithuania) at 54° 42' N, 25° 08 E, 158 masl. Four days after the fire, it was designed in a burned area a plot with 400 m2 (20 x 20 m with 5 m space between sampling points). Twenty five samples from top soil (0-5 cm) were collected immediately after the fire (IAF), 2, 5, 7 and 9 months after the fire (a total of 125 in all sampling dates). The original data of water-extractable calcium and magnesium did not respected the Gaussian distribution, thus a neperian logarithm (ln) was applied in order to normalize data. Significant differences of water-extractable calcium and magnesium among sampling dates were carried out with the Anova One-way test using the ln data. In order to assess the spatial variability of water-extractable calcium and magnesium, we tested several interpolation methods as Ordinary Kriging (OK), Inverse Distance to a Weight (IDW) with the power of 1, 2, 3 and 4, Radial Basis Functions (RBF) - Inverse Multiquadratic (IMT), Multilog (MTG), Multiquadratic (MTQ) Natural Cubic Spline (NCS) and Thin Plate Spline (TPS) - and Local Polynomial (LP) with the power of 1 and 2. Interpolation tests were carried out with Ln data. The best interpolation method was assessed using the

  9. Climate Variability Program

    NASA Technical Reports Server (NTRS)

    Halpern, David (Editor)

    2002-01-01

    The Annual Report of the Climate Variability Program briefly describes research activities of Principal Investigators who are funded by NASA's Earth Science Enterprise Research Division. The report is focused on the year 2001. Utilization of satellite observations is a singularity of research on climate science and technology at JPL (Jet Propulsion Laboratory). Research at JPL has two foci: generate new knowledge and develop new technology.

  10. Long commuting time, extensive overtime, and sympathodominant state assessed in terms of short-term heart rate variability among male white-collar workers in the Tokyo megalopolis.

    PubMed

    Kageyama, T; Nishikido, N; Kobayashi, T; Kurokawa, Y; Kaneko, T; Kabuto, M

    1998-07-01

    To investigate the possible effects of long commuting time and extensive overtime on daytime cardiac autonomic activity, the short-term heart rate variability (HRV) both at supine rest and at standing rest of 223 male white-collar workers in the Tokyo Megalopolis was examined. Workers with a one-way commute of 90 min or more exhibited decreased vagal activity at supine rest and increased sympathetic activity regardless of posture, and those doing overtime of 60 h/month or more exhibited decreased vagal activity and increased sympathetic activity at standing rest. These findings suggest that chronic stress or fatigue resulting from long commuting time or extensive overtime caused these individuals to be in a sympathodominant state. Although these shifts in autonomic activities are not direct indicators of disease, it can be hypothesized that they can induce cardiovascular abnormalities or dysfunctions related to the onset of heart disease. Assessment of the daily and weekly variations in HRV as a function of daily life activities (such as working, commuting, sleeping, and exercising) among workers in Asia-Pacific urban areas might be one way of studying the possible effects of long commuting time, and extensive overtime, on health. PMID:9701898

  11. Short-term fluctuations in vegetation and phytoplankton during the Middle Eocene greenhouse climate: a 640-kyr record from the Messel oil shale (Germany)

    NASA Astrophysics Data System (ADS)

    Lenz, Olaf K.; Wilde, Volker; Riegel, Walter

    2011-11-01

    The Palaeogene was the most recent greenhouse period on Earth. Especially for the Late Palaeocene and Early Eocene, several superimposed short-term hyperthermal events have been described, including extremes such as the Palaeocene-Eocene Thermal Maximum. Major faunal and floral turnovers in the marine and terrestrial realms were recorded in association with these events. High-resolution palynological analysis of the early Middle Eocene maar lake sediments at Messel, near Darmstadt, Germany, provides an insight into the dynamics of a climax vegetation during the Middle Eocene greenhouse climate in a time span without significant climatic excursions. Numerical techniques like detrended correspondence analysis and wavelet analysis have been applied to recognize cyclic fluctuations and long-term trends in the vegetation through a time interval of approximately 640 kyr. Based on the numerical zoning of the pollen diagram, three phases in the development of the vegetation may be distinguished. Throughout these phases, the climax vegetation did not change substantially in qualitative composition, but a trend towards noticeably less humid conditions probably in combination with a drop of the water level in the lake may be recognized. A shift in algal population from the freshwater dinoflagellate cyst Messelodinium thielepfeifferae to a dominance of Botryococcus in the uppermost part of the core is interpreted as a response to changes in acidity and nutrient availability within the lake. Time series analyses of pollen assemblages show that variations in the Milankovitch range of eccentricity, obliquity and precession can be distinguished. In addition, fluctuations in the sub-Milankovitch range are indicated. This demonstrates that floral changes during steady depositional conditions in the Middle Eocene of Messel were controlled by orbital forcing.

  12. Short-term variability in QT interval and ventricular arrhythmias induced by dofetilide are dependent on high-frequency autonomic oscillations

    PubMed Central

    Champeroux, P; Thireau, J; Judé, S; Laigot-Barbé, C; Maurin, A; Sola, M L; Fowler, J S L; Richard, S; Le Guennec, J Y

    2015-01-01

    Background and Purpose The present study was undertaken to investigate an effect of dofetilide, a potent arrhythmic blocker of the voltage-gated K+ channel, hERG, on cardiac autonomic control. Combined with effects on ardiomyocytes, these properties could influence its arrhythmic potency. Experimental Approach The short-term variability of beat-to-beat QT interval (STVQT), induced by dofetilide is a strong surrogate of Torsades de pointes liability. Involvement of autonomic modulation in STVQT was investigated in healthy cynomolgus monkeys and beagle dogs by power spectral analysis under conditions of autonomic blockade with hexamethonium. Key Results Increase in STVQT induced by dofetilide in monkeys and dogs was closely associated with an enhancement of endogenous heart rate and QT interval high-frequency (HF) oscillations. These effects were fully suppressed under conditions of autonomic blockade with hexamethonium. Ventricular arrhythmias, including Torsades de pointes in monkeys, were prevented in both species when HF oscillations were suppressed by autonomic blockade. Similar enhancements of heart rate HF oscillations were found in dogs with other hERG blockers described as causing Torsades de pointes in humans. Conclusions and Implications These results demonstrate for the first time that beat-to-beat ventricular repolarization variability and ventricular arrhythmias induced by dofetilide are dependent on endogenous HF autonomic oscillations in heart rate. When combined with evidence of hERG-blocking properties, enhancement of endogenous HF oscillations in heart rate could constitute an earlier and more sensitive biomarker than STVQT for Torsades de pointes liability, applicable to preclinical regulatory studies conducted in healthy animals. PMID:25625756

  13. Zoonoses and climate variability.

    PubMed

    Cardenas, Rocio; Sandoval, Claudia M; Rodriguez-Morales, Alfonso J; Vivas, Paul

    2008-12-01

    Leishmaniasis in the Americas is transmitted by Lutzomyia spp., which have many animal reservoirs. Previous studies indicated potential changes in vectors of climate-related distribution, but impact outcomes need to be further studied. We report climatic and El Niño events during 1985-2002 that may have had an impact on leishmaniasis in 11 southern departments of Colombia: Amazonas, Caquetá, Cauca (Ca), Huila, Meta (Mt), Nariño, Putumayo (Py), Tolima, Valle (Va), Vaupes (Vp), and Vichada. Climatic data were obtained by satellite and epidemiologic data were obtained from the Health Ministry. NOAA climatic classification and SOI/ONI indexes were used as indicators of global climate variability. Yearly variation comparisons and median trend deviations were made for disease incidence and climatic variability. During this period there was considerable climatic variability, with a strong El Niño for 6 years and a strong La Niña for 8. During this period, 19,212 cases of leishmaniasis were registered, for a mean of 4756.83 cases/year. Disease in the whole region increased (mean of 4.98%) during the El Niño years in comparison to the La Niña years, but there were differences between departments with increases during El Niño (Mt 6.95%, Vp 4.84%), but the rest showed an increase during La Niña (1.61%-64.41%). Differences were significant in Va (P= 0.0092), Py (P= 0.0001), Ca (P= 0.0313), and for the whole region (P= 0.0023), but not in the rest of the departments. The importance of climate change is shown by shifts in insect and animal distributions. These data reflect the importance of climate on transmission of leishmaniasis and open further investigations related to forecasting and monitoring systems, where understanding the relationship between zoonoses and climate variability could help to improve the management of these emerging and reemerging diseases. PMID:19120241

  14. Current Climate Variability & Change

    NASA Astrophysics Data System (ADS)

    Diem, J.; Criswell, B.; Elliott, W. C.

    2013-12-01

    Current Climate Variability & Change is the ninth among a suite of ten interconnected, sequential labs that address all 39 climate-literacy concepts in the U.S. Global Change Research Program's Climate Literacy: The Essential Principles of Climate Sciences. The labs are as follows: Solar Radiation & Seasons, Stratospheric Ozone, The Troposphere, The Carbon Cycle, Global Surface Temperature, Glacial-Interglacial Cycles, Temperature Changes over the Past Millennium, Climates & Ecosystems, Current Climate Variability & Change, and Future Climate Change. All are inquiry-based, on-line products designed in a way that enables students to construct their own knowledge of a topic. Questions representative of various levels of Webb's depth of knowledge are embedded in each lab. In addition to the embedded questions, each lab has three or four essential questions related to the driving questions for the lab suite. These essential questions are presented as statements at the beginning of the material to represent the lab objectives, and then are asked at the end as questions to function as a summative assessment. For example, the Current Climate Variability & Change is built around these essential questions: (1) What has happened to the global temperature at the Earth's surface, in the middle troposphere, and in the lower stratosphere over the past several decades?; (2) What is the most likely cause of the changes in global temperature over the past several decades and what evidence is there that this is the cause?; and (3) What have been some of the clearly defined effects of the change in global temperature on the atmosphere and other spheres of the Earth system? An introductory Prezi allows the instructor to assess students' prior knowledge in relation to these questions, while also providing 'hooks' to pique their interest related to the topic. The lab begins by presenting examples of and key differences between climate variability (e.g., Mt. Pinatubo eruption) and

  15. Utility of short-term variability of repolarization as a marker for monitoring a safe exercise training program in patients with cardiac diseases.

    PubMed

    Nishi, Isao; Sugiyama, Atsushi; Takahara, Akira; Kuroki, Kenji; Igawa, Masayuki; Enomoto, Tsuyoshi; Iida, Kaname; Koseki, Susumu; Aonuma, Kazutaka

    2011-01-01

    In order to begin searching for new markers for safe exercise training in patients with cardiac diseases, we tested the sensitivity and reliability of the short-term variability of repolarization (STV(QT)) in comparison with QT interval, QTc, and T(peak)-T(end) interval (T(p-e)) in patients with cardiac diseases. Nine patients (8 men, 1 woman; 58 ± 10 years) were enrolled. The cardiac rehabilitation (CR) program consisted of walking, bicycling on an ergometer, and calisthenics for 30-50 minutes/session and 3-5 sessions/week for 3 months. ECGs of 31 consecutive sinus beats were obtained before and after the CR program. RR and QT intervals were measured in the aVL lead. The mean orthogonal distance from the diagonal to the points of the Poincaré plots was determined using the following equation; STV(QT) [= Σ |QT(n+1)-QT(n)/(30 × 2(1/2))], as a marker of temporal dispersion of repolarization. Also, T(p-e) of 5 consecutive beats was measured as a marker of spatial dispersion. No fatal arrhythmias were observed in the CR. No significant difference was observed in the RR or QT interval between at baseline and at the end of the CR program. Meanwhile, QTc, STV(QT) and T(p-e) decreased significantly from 429 ± 27 to 400 ± 17 (P < 0.01), from 6.8 ± 1.3 to 4.7 ± 1.4 msec (P < 0.001), and from 74.8 (61.2/79.1) to 64.8 (51.4/70.7) msec (median (25th/75th percentile), P < 0.01), respectively. STV(QT) together with T(p-e) and QTc may reflect the time-courses of safe exercise training. PMID:22008441

  16. Association between short term exposure to fine particulate matter and heart rate variability in older subjects with and without heart disease

    PubMed Central

    Sullivan, J; Schreuder, A; Trenga, C; Liu, S; Larson, T; Koenig, J; Kaufman, J

    2005-01-01

    Background: Short term increases in exposure to particulate matter (PM) air pollution are associated with increased cardiovascular morbidity and mortality. The mechanism behind this effect is unclear, although changes in autonomic control have been observed. It was hypothesised that increases in fine PM measured at the subjects' home in the preceding hour would be associated with decreased high frequency heart rate variability (HF-HRV) in individuals with pre-existing cardiac disease. Methods: Two hundred and eighty five daily 20 minute measures of HRV (including a paced breathing protocol) were made in the homes of 34 elderly individuals with (n = 21) and without (n = 13) cardiovascular disease (CVD) over a 10 day period in Seattle between February 2000 and March 2002. Fine PM was continuously measured by nephelometry at the individuals' homes. Results: The median age of the study population was 77 years (range 57–87) and 44% were male. Models that adjusted for health status, relative humidity, temperature, mean heart rate, and medication use did not find a significant association between a 10 µg/m3 increase in 1 hour mean outdoor PM2.5 before the HRV measurement and a change in HF-HRV power in individuals with CVD (3% increase in median HF-HRV (95% CI –19 to 32)) or without CVD (5% decrease in median HF-HRV (95% CI –34 to 36)). Similarly, no association was evident using 4 hour and 24 hour mean outdoor PM2.5 exposures before the HRV measurement. Conclusion: No association was found between increased residence levels of fine PM and frequency domain measures of HRV in elderly individuals. PMID:15923245

  17. Climate Variability and Change

    USGS Publications Warehouse

    U.S. Geological Survey

    2007-01-01

    In 2007, the U.S. Geological Survey (USGS) developed a science strategy outlining the major natural science issues facing the Nation in the next decade. The science strategy consists of six science directions of critical importance, focusing on areas where natural science can make a substantial contribution to the well-being of the Nation and the world. This fact sheet focuses on climate variability and change and how USGS research can strengthen the Nation with information needed to meet the challenges of the 21st century.

  18. Short-term Variability of Physical and Chemical Parameters in Suboxic/Anoxic Bottom Waters of the Chesapeake Bay During Late July 2002.

    NASA Astrophysics Data System (ADS)

    Montbriand, P. J.; Lewis, B. L.; Luther, G. W.; Glazer, B. T.; Ma, S.; Reedy, S.; Nuzzio, D. B.; Spencer, T.; Theberge, S.

    2002-12-01

    concentrations of ~40-70 μM (7-12 m depth), and 0.1-0.3 μM nitrite was observed in the surface layer. In the bottom waters, nitrite increased over the sampling period from 0 to about 0.07 μM. The data imply two sources of nitrite, ammonification/nitrification in the oxygenated waters and denitrification in the deep waters. Dissolved Mn increased below 12-14 meters, coincident with oxygen concentrations < 20 μM. Concentrations in the deep waters varied widely, from ~ 0.2 to 7 μM. Dissolved Fe(II) was detected only at oxygen levels < 5 μM, with concentrations in the deep waters ranging from ~ 0.2 to 1.4 μM. Plotting the chemical data versus salinity rather than depth decreases the scatter due to tidal variation and displays a clear separation between the onset of Mn and Fe reduction. This study illustrates the dynamic, rapidly changing nature of water-column anoxia in the Chesapeake Bay. The depth of oxygen penetration, the thickness of the suboxic zone and the concentration of sulfide in the deep waters fluctuate in response to tidal oscillations and to the passage of storm events. Real-time measurements are necessary to document these short-term variations.

  19. Short-term effects of controlling fossil-fuel soot, biofuel soot and gases, and methane on climate, Arctic ice, and air pollution health

    NASA Astrophysics Data System (ADS)

    Jacobson, Mark Z.

    2010-07-01

    This study examines the short-term (˜15 year) effects of controlling fossil-fuel soot (FS) (black carbon (BC), primary organic matter (POM), and S(IV) (H2SO4(aq), HSO4-, and SO42-)), solid-biofuel soot and gases (BSG) (BC, POM, S(IV), K+, Na+, Ca2+, Mg2+, NH4+, NO3-, Cl- and several dozen gases, including CO2 and CH4), and methane on global and Arctic temperatures, cloudiness, precipitation, and atmospheric composition. Climate response simulations were run with GATOR-GCMOM, accounting for both microphysical (indirect) and radiative effects of aerosols on clouds and precipitation. The model treated discrete size-resolved aging and internal mixing of aerosol soot, discrete size-resolved evolution of clouds/precipitation from externally and internally mixed aerosol particles, and soot absorption in aerosols, clouds/precipitation, and snow/sea ice. Eliminating FS, FS+BSG (FSBSG), and CH4 in isolation were found to reduce global surface air temperatures by a statistically significant 0.3-0.5 K, 0.4-0.7 K, and 0.2-0.4 K, respectively, averaged over 15 years. As net global warming (0.7-0.8 K) is due mostly to gross pollutant warming from fossil-fuel greenhouse gases (2-2.4 K), and FSBSG (0.4-0.7 K) offset by cooling due to non-FSBSG aerosol particles (-1.7 to -2.3 K), removing FS and FSBSG may reduce 13-16% and 17-23%, respectively, of gross warming to date. Reducing FS, FSBSG, and CH4 in isolation may reduce warming above the Arctic Circle by up to ˜1.2 K, ˜1.7 K, and ˜0.9 K, respectively. Both FS and BSG contribute to warming, but FS is a stronger contributor per unit mass emission. However, BSG may cause 8 times more mortality than FS. The global e-folding lifetime of emitted BC (from all fossil sources) against internal mixing by coagulation was ˜3 h, similar to data, and that of all BC against dry plus wet removal was ˜4.7 days. About 90% of emitted FS BC mass was lost to internal mixing by coagulation, ˜7% to wet removal, ˜3% to dry removal, and a residual

  20. Climate Impact of Solar Variability

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H. (Editor); Arking, Albert (Editor)

    1990-01-01

    The conference on The Climate Impact of Solar Variability, was held at Goddard Space Flight Center from April 24 to 27, 1990. In recent years they developed a renewed interest in the potential effects of increasing greenhouse gases on climate. Carbon dioxide, methane, nitrous oxide, and the chlorofluorocarbons have been increasing at rates that could significantly change climate. There is considerable uncertainty over the magnitude of this anthropogenic change. The climate system is very complex, with feedback processes that are not fully understood. Moreover, there are two sources of natural climate variability (volcanic aerosols and solar variability) added to the anthropogenic changes which may confuse our interpretation of the observed temperature record. Thus, if we could understand the climatic impact of the natural variability, it would aid our interpretation and understanding of man-made climate changes.

  1. [Short-term occupational disability].

    PubMed

    Bebensee, H; Conrad, P; Hein, R

    1994-01-01

    The present political discussion about absenteeism in industry and introduction of days of absence in case of sickness emphasises the amount of short-term sickness cases. More or less openly the misuse of continued salary payment via "unauthorized" working inability is discussed: this is often connected with the increased absenteeism on Mondays and Fridays. From the point of view of the Legal Health Insurances this thesis of misuse is investigated in an analysis of cases of short-term work disability. PMID:8148587

  2. Short-term variability of 7Be atmospheric deposition and watershed response in a Pacific coastal stream, Monterey Bay, California, USA

    USGS Publications Warehouse

    Conaway, Christopher H.; Storlazzi, Curt D.; Draut, Amy E.; Swarzenski, Peter W.

    2013-01-01

    Beryllium-7 is a powerful and commonly used tracer for environmental processes such as watershed sediment provenance, soil erosion, fluvial and nearshore sediment cycling, and atmospheric fallout. However, few studies have quantified temporal or spatial variability of 7Be accumulation from atmospheric fallout, and parameters that would better define the uses and limitations of this geochemical tracer. We investigated the abundance and variability of 7Be in atmospheric deposition in both rain events and dry periods, and in stream surface-water samples collected over a ten-month interval at sites near northern Monterey Bay (37°N, 122°W) on the central California coast, a region characterized by a rainy winters, dry summers, and small mountainous streams with flashy hydrology. The range of 7Be activity in rainwater samples from the main sampling site was 1.3–4.4 Bq L−1, with a mean (±standard deviation) of 2.2 ± 0.9 Bq L−1, and a volume-weighted average of 2.0 Bq L−1. The range of wet atmospheric deposition was 18–188 Bq m−2 per rain event, with a mean of 72 ± 53 Bq m−2. Dry deposition fluxes of 7Be ranged from less than 0.01 up to 0.45 Bq m−2 d−1, with an estimated dry season deposition of 7 Bq m−2 month−1. Annualized 7Be atmospheric deposition was approximately 1900 Bq m−2 yr−1, with most deposition via rainwater (>95%) and little via dry deposition. Overall, these activities and deposition fluxes are similar to values found in other coastal locations with comparable latitude and Mediterranean-type climate. Particulate 7Be values in the surface water of the San Lorenzo River in Santa Cruz, California, ranged from −1 to 0.6 Bq g−1, with a median activity of 0.26 Bq g−1. A large storm event in January 2010 characterized by prolonged flooding resulted in the entrainment of 7Be-depleted sediment, presumably from substantial erosion in the watershed. There were too few particulate 7Be data over the storm to accurately model a 7Be load

  3. Natural Climate Variability and Future Climate Policy

    NASA Astrophysics Data System (ADS)

    Ricke, K.; Caldeira, K.

    2013-12-01

    Individual beliefs about climate change and willingness-to-pay for its mitigation are influenced by local weather and climate. Large ensemble climate modeling experiments have demonstrated the large role natural variability plays in local weather and climate on a multidecadal timescale. Here we illustrate how if support for global climate policies and subsequent implementation of those policies are determined by citizens' local experiences, natural variability could influence the timeline for implementation of emissions reduction policies by decades. The response of complex social systems to local and regional changes in weather and climate cannot be quantitatively predicted with confidence. Both the form and timing of the societal response can be affected by interactions between social systems and the physical climate system. Here, to illustrate one type of influence decadal natural variability can have on climate policy, we consider a simple example in which the only question is when, if ever, the different parties will support emissions reduction. To analyze the potential effect that unpredictable extreme events may have on the time to reach a global agreement on climate policy, we analyzed the output from a 40-member Community Climate System Model version 3 simulation ensemble to illustrate how local experiences might affect the timing of acceptance of strong climate policy measures. We assume that a nation's decision to take strong actions to abate emissions is contingent upon the local experiences of its citizens and then examine how the timelines for policy action may be influenced by variability in local weather. To illustrate, we assume that a social 'tipping point' is reached at the national level occurs when half of the population of a nation has experienced a sufficiently extreme event. If climate policies are driven by democratic consensus then variability in weather could result in significantly disparate times-to-action. For the top six CO2 emitters

  4. Intraseasonal Variability in the Atmosphere-Ocean Climate System. Second Edition

    NASA Technical Reports Server (NTRS)

    Lau, William K. M.; Waliser, Duane E.

    2011-01-01

    Understanding and predicting the intraseasonal variability (ISV) of the ocean and atmosphere is crucial to improving long-range environmental forecasts and the reliability of climate change projections through climate models. This updated, comprehensive and authoritative second edition has a balance of observation, theory and modeling and provides a single source of reference for all those interested in this important multi-faceted natural phenomenon and its relation to major short-term climatic variations.

  5. NPOESS, Essential Climates Variables and Climate Change

    NASA Astrophysics Data System (ADS)

    Forsythe-Newell, S. P.; Bates, J. J.; Barkstrom, B. R.; Privette, J. L.; Kearns, E. J.

    2008-12-01

    Advancement in understanding, predicting and mitigating against climate change implies collaboration, close monitoring of Essential Climate Variable (ECV)s through development of Climate Data Record (CDR)s and effective action with specific thematic focus on human and environmental impacts. Towards this end, NCDC's Scientific Data Stewardship (SDS) Program Office developed Climate Long-term Information and Observation system (CLIO) for satellite data identification, characterization and use interrogation. This "proof-of-concept" online tool provides the ability to visualize global CDR information gaps and overlaps with options to temporally zoom-in from satellite instruments to climate products, data sets, data set versions and files. CLIO provides an intuitive one-stop web site that displays past, current and planned launches of environmental satellites in conjunction with associated imagery and detailed information. This tool is also capable of accepting and displaying Web-based input from Subject Matter Expert (SME)s providing a global to sub-regional scale perspective of all ECV's and their impacts upon climate studies. SME's can access and interact with temporal data from the past and present, or for future planning of products, datasets/dataset versions, instruments, platforms and networks. CLIO offers quantifiable prioritization of ECV/CDR impacts that effectively deal with climate change issues, their associated impacts upon climate, and this offers an intuitively objective collaboration and consensus building tool. NCDC's latest tool empowers decision makers and the scientific community to rapidly identify weaknesses and strengths in climate change monitoring strategies and significantly enhances climate change collaboration and awareness.

  6. Emotional Availability in Mother-Child Dyads: Short-Term Stability and Continuity from Variable-Centered and Person-Centered Perspectives

    ERIC Educational Resources Information Center

    Bornstein, Marc H.; Gini, Motti; Suwalsky, Joan T. D.; Putnick, Diane L.; Haynes, O. Maurice

    2006-01-01

    Emotional availability (EA) is a prominent index of socioemotional adaptation in the parent-child dyad. Can basic psychometric properties of EA be looked at from both variable (scale) and person (cluster) points of view in individuals and in dyads? Is EA stable and continuous over a short period of time? This methodological study shows significant…

  7. Short-Term and Long-Term Variability of Antenna Position Due to Thermal Bending of Pillar Monument at Permanent GNSS Station

    NASA Astrophysics Data System (ADS)

    Gerhatova, Lubomira; Hefty, Jan; Spanik, Peter

    2016-06-01

    The variability of daily site coordinates at permanent GNSS station is a sum of many disturbing factors influencing the actual satellite observations, data processing, and bias modelling. In the paper are analysed possibilities of monitoring the instability of GNSS antenna pillar monument by the independent observations using the precise inclination sensor. Long-term series from three different types of pillars show specific features in amplitude and temporal evolution of monument bending. Correlations with daily temperature and/or solar radiation changes were proved.

  8. Evolution and climate variability

    SciTech Connect

    Potts, R.

    1996-08-16

    Variations in organisms are preserved and accrue if there is a consistent bias in selection over many generations. This idea of long-term directional selection has been embraced to explain major adaptive change. It is widely thought that important adaptive shifts in hominids corresponded with directional environmental change. This view, which echoes the savanna scenario of hominid evolution, has strongly been supported by paleontologists and paleoclimatologists over the past decade. The origin of the hominids, bipedality, stone toolmaking, and brain size increase have all been related to cooling, aridification, and savanna expansion. However there appears to be a more prominent signal than the aridity trend: an increase in the range of climatic variation over time. This article discusses the possible reprocussions of this interpertation. 13 refs.

  9. Short-term variability of biomarkers of proteinase activity in patients with emphysema associated with type Z alpha-1-antitrypsin deficiency

    PubMed Central

    Stolk, Jan; Veldhuisen, Barbara; Annovazzi, Laura; Zanone, Chiara; Versteeg, Elly M; van Kuppevelt, Toine H; Nieuwenhuizen, Willem; Iadarola, Paolo; Luisetti, Maurizio

    2005-01-01

    Background The burden of proteinases from inflammatory cells in the lung of subjects with type Pi ZZ of alpha-1-antitrypsin deficiency is higher than in those without the deficiency. Cross-sectional studies have shown increased levels of biomarkers of extracellular matrix degradation in vivo. Longitudinal variability of these biomarkers is unknown but desirable for clinical studies with proteinase inhibitors. Methods We measured three different types of biomarkers, including desmosines, elastase-formed fibrinogen fragments and heparan sulfate epitope JM403, in plasma and urine for a period of 7 weeks in a group of 12 patients who participated in a placebo-controlled study to assess the safety of a single inhalation of hyaluronic acid. Results Effect of study medication on any of the biomarkers was not seen. Baseline desmosines in plasma and urine correlated with baseline CO diffusion capacity (R = 0.81, p = 0.01 and R = 0.65, p = 0.05). Mean coefficient of variation within patients (CVi) for plasma and urine desmosines was 18.7 to 13.5%, respectively. Change in urinary desmosine levels correlated significantly with change in plasma desmosine levels (R = 0.84, p < 0.01). Mean CVi for fibrinogen fragments in plasma was 20.5% and for JM403 in urine was 27.8%. No correlations were found between fibrinogen fragments or JM403 epitope and desmosines. Conclusion We found acceptable variability in our study parameters, indicating the feasibility of their use in an evaluation of biochemical efficacy of alpha-1-antitrypsin augmentation therapy in Pi Z subjects. PMID:15927063

  10. Short-term and seasonal pH,pCO2and saturation state variability in a coral-reef ecosystem

    NASA Astrophysics Data System (ADS)

    Gray, Sarah E. C.; Degrandpre, Michael D.; Langdon, Chris; Corredor, Jorge E.

    2012-09-01

    Coral reefs are predicted to be one of the ecosystems most sensitive to ocean acidification. To improve predictions of coral reef response to acidification, we need to better characterize the natural range of variability of pH, partial pressure of carbon dioxide (pCO2) and calcium carbonate saturation states (Ω). In this study, autonomous sensors for pH and pCO2 were deployed on Media Luna reef, Puerto Rico over three seasons from 2007 to 2008. High temporal resolution CaCO3 saturation states were calculated from the in situ data, giving a much more detailed characterization of reef saturation states than previously possible. Reef pH, pCO2 and aragonite saturation (ΩAr) ranged from 7.89 to 8.17 pH units, 176-613 μatm and 2.7-4.7, respectively, in the range characteristic of most other previously studied reef ecosystems. The diel pH, pCO2 and Ω cycles were also large, encompassing about half of the seasonal range of variability. Warming explained about 50% of the seasonal supersaturation in mean pCO2, with the remaining supersaturation primarily due to net heterotrophy and net CaCO3 production. Net heterotrophy was likely driven by remineralization of mangrove derived organic carbon which continued into the fall, sustaining high pCO2 levels until early winter when the pCO2 returned to offshore values. As a consequence, the reef was a source of CO2 to the atmosphere during the summer and fall and a sink during winter, resulting in a net annual source of 0.73 ± 1.7 mol m-2 year-1. These results show that reefs are exposed to a wide range of saturation states in their natural environment. Mean ΩAr levels will drop to 3.0 when atmospheric CO2 increases to 500 μatm and ΩAr will be less than 3.0 for greater than 70% of the time in the summer. Long duration exposure to these low ΩAr levels are expected to significantly decrease calcification rates on the reef.

  11. Short-term variability in the sedimentary BIT index of Lake Challa, East Africa over the past 2200 years: validating the precipitation proxy

    NASA Astrophysics Data System (ADS)

    Buckles, L. K.; Weijers, J. W. H.; Verschuren, D.; Cocquyt, C.; Sinninghe Damsté, J. S.

    2015-04-01

    The branched vs. isoprenoid index of tetraethers (BIT index) in Lake Challa sediments has been applied as a monsoon precipitation proxy on the assumption that the primary source of branched tetraether lipids (brGDGTs) was soil washed in from the lake's catchment. However, water column production has since been identified as the primary source of brGDGTs in Lake Challa, meaning that there is no longer a clear mechanism linking BIT index variation and precipitation. Here we investigate BIT index variation and GDGT concentrations at a decadal resolution over the past 2200 years, in combination with GDGT data from profundal surface sediments and 45 months of sediment-trap deployment. The 2200 year record reveals high-frequency variability in GDGT concentrations, and therefore the BIT index. Also surface sediments collected in January 2010 show a distinct shift in GDGT composition relative to those collected in August 2007. Increased bulk flux of settling particles with high Ti / Al ratios during March-April 2008 reflect an event of high detrital input to Lake Challa, concurrent with intense precipitation at the onset of the principal rain season that year. Although brGDGT distributions in the settling material are initially unaffected, this soil erosion event is succeeded by a large diatom bloom in July-August 2008 and a concurrent increase in GDGT-0 fluxes. Near-zero crenarchaeol fluxes indicate that no thaumarchaeotal bloom developed during the subsequent austral summer season; instead a peak in brGDGT fluxes is observed in December 2008. We suggest that increased nutrient availability, derived from eroded soil washed into the lake, stimulated both diatom productivity and the GDGT-0 producing archaea which help decompose dead diatoms passing through the suboxic zone of the water column. This disadvantaged the Thaumarchaeota that normally prosper during the following austral summer. Instead, a bloom of supposedly heterotrophic brGDGT-producing bacteria occurred

  12. Effect of yoga on short-term heart rate variability measure as a stress index in subjunior cyclists: a pilot study.

    PubMed

    Patil, Satish G; Mullur, Lata M; Khodnapur, Jyoti P; Dhanakshirur, Gopal B; Aithala, Manjunatha R

    2013-01-01

    Subjunior athletes experience mental stress due to pressure from the coach, teachers and parents for better performance. Stress, if remains for longer period and not managed appropriately can leads to negative physical, mental and cognitive impact on children. The present study was aimed to evaluate the effect of integrated yoga module on heart rate variability (HRV) measure as a stress index in subjunior cyclists. Fast furrier transform technique of frequency domain method was used for the analysis of HRV. We have found a significant increase in high frequency (HF) component by 14.64% (P < 0.05) and decrease in the low frequency component (LF) of HRV spectrum by 5.52% (P < 0.05) and a decrease in LF/HF ratio by 19.63% (P < 0.01) in yoga group. In the control group, there was decrease in the HF component and, no significant difference in the LF component of HRV spectrum and LF/HF ratio. The results show that yoga practice decreases sympathetic activity and causes a shift in the autonomic balance towards parasympathetic dominance indicating a reduction in stress. In conclusion, yoga practice helps to reduce stress by optimizing the autonomic functions. So, it is suggested to incorporate yoga module as a regular feature to keep subjunior athletes both mentally and physically fit. PMID:24617165

  13. Short-term hydrophysical and biological variability over the northeastern Black Sea continental slope as inferred from multiparametric tethered profiler surveys

    NASA Astrophysics Data System (ADS)

    Ostrovskii, Alexander; Zatsepin, Andrey

    2011-06-01

    This presentation introduces a new ocean autonomous profiler for multiparametric surveys at fixed geographical locations. The profiler moves down and up along a mooring line, which is taut vertically between a subsurface flotation and an anchor. This observational platform carries such modern oceanographic equipment as the Nortek Aquadopp-3D current meter and the Teledyne RDI Citadel CTD-ES probe. The profiler was successfully tested in the northeastern Black Sea during 2007-2009. By using the profiler, new data on the layered organization of the marine environment in the waters over the upper part of the continental slope were obtained. The temporal variability of the fine-scale structure of the acoustic backscatter at 2 MHz was interpreted along with biooptical and chemical data. The patchy patterns of the acoustic backscatter were associated with physical and biological processes such as the advection, propagation of submesoscale eddy, thermocline displacement, and diel migration of zooplankton. Further applications of the multidisciplinary moored profiler technology are discussed.

  14. Glycemic Variability Assessed by Continuous Glucose Monitoring and Short-Term Outcome in Diabetic Patients Undergoing Percutaneous Coronary Intervention: An Observational Pilot Study.

    PubMed

    Nusca, Annunziata; Lauria Pantano, Angelo; Melfi, Rosetta; Proscia, Claudio; Maddaloni, Ernesto; Contuzzi, Rocco; Mangiacapra, Fabio; Palermo, Andrea; Manfrini, Silvia; Pozzilli, Paolo; Di Sciascio, Germano

    2015-01-01

    Poor glycemic control is associated with unfavorable outcome in patients undergoing percutaneous coronary intervention (PCI), irrespective of diabetes mellitus. However a complete assessment of glycemic status may not be fully described by glycated hemoglobin or fasting blood glucose levels, whereas daily glycemic fluctuations may influence cardiovascular risk and have even more deleterious effects than sustained hyperglycemia. Thus, this paper investigated the effectiveness of a continuous glucose monitoring (CGM), registering the mean level of glycemic values but also the extent of glucose excursions during coronary revascularization, in detecting periprocedural outcome such as renal or myocardial damage, assessed by serum creatinine, neutrophil gelatinase-associated lipocalin (NGAL), and troponin I levels. High glycemic variability (GV) has been associated with worse postprocedural creatinine and NGAL variations. Moreover, GV, and predominantly hypoglycemic variations, has been observed to increase in patients with periprocedural myocardial infarction. Thus, our study investigated the usefulness of CGM in the setting of PCI where an optimal glycemic control should be achieved in order to prevent complications and improve outcome. PMID:26273664

  15. Impact of short-term climate variation and hydrology change on thermal structure and water quality of a canyon-shaped, stratified reservoir.

    PubMed

    Ma, Wei-Xing; Huang, Ting-Lin; Li, Xuan; Zhang, Hai-Han; Ju, Tuo

    2015-12-01

    Climate variation can have obvious effects on hydrologic conditions, which in turn can have direct consequences for the thermal regime and quality of water for human use. In this research, weekly surveys were conducted from 2011 to 2013 to investigate how changes of climate and hydrology affect the thermal regime and water quality at the Heihe Reservoir. Our results show that the hydrology change during the flooding season can both increase the oxygen concentration and accelerate the consumption of dissolved oxygen. Continuous heavy rainfall events occurred in September 2011 caused the mixing of the entire reservoir, which led to an increase in dissolved oxygen at the bottom until the next year. Significant turbid density flow was observed following the extreme rainfall events in 2012 which leading to a rapid increase in turbidity at the bottom (up to 3000 NTU). Though the dissolved oxygen at the bottom increased from 0 to 9.02 mg/L after the rainfall event, it became anoxic within 20 days due to the increase of water oxygen demand caused by the suspended matter brought by the storm runoff. The release of compounds from the sediments was more serious during the anaerobic period after the rainfall events and the concentration of total iron, total phosphorus, and total manganese at the bottom reached 1.778, 0.102, and 0.125 mg/L. The improved water-lifting aerators kept on running after the storm runoff occurred in 2013 to avoid the deterioration of water quality during anaerobic conditions and ensured the good water quality during the mixing period. Our results suggest preventive and remediation actions that are necessary to improve water quality and status. PMID:26194232

  16. Response of planktonic cladocerans (Class: Branchiopoda) to short-term changes in environmental variables in the surface waters of the Bay of Biscay

    NASA Astrophysics Data System (ADS)

    d'Elbée, Jean; Lalanne, Yann; Castège, Iker; Bru, Noelle; D'Amico, Frank

    2014-08-01

    From January 2001 to December 2008, 73 surface plankton samples and 45 vertical profiles of sea temperature, salinity, dissolved oxygen and pH were collected on a monthly basis from a single sampling station located in the Bay of Biscay (43°37N; 1°43W) (North-East Atlantic). Two types of North Atlantic Oscillation (NAO) indexes were included in the data set and submitted to a Canonical Correspondence Analysis and Spearman non-parametric test. Significant breaks and levels in time series were tested using a data segmentation method. The temperature range varies from 11 °C to 25 °C. It begins to rise from April until August and then decline. Low salinity values occur in mid-spring (<34 PSU) and high values (>36 PSU) in autumn. Dissolved oxygen mean values were around 8 mg/l. In summer, when temperature and salinity are high, surface water layer is always accompanied with a significant deoxygenation, and the process reverses in winter. pH mean values range was 7.78-8.33. Seasonal and inter-annual variations of the two NAO indexes are strongly correlated to one another, but do not correlate with any hydrological or biological variable. Five of the seven cladocerans species which are present in the Bay of Biscay were found in this study. There is a strong pattern in species succession throughout the year: Evadne nordmanni is a vernal species, while Penilia avirostris and Pseudevadne tergestina occur mainly in summer and autumn. Evadne spinifera has a maximum abundance in spring, Podon intermedius in autumn, but they both occur throughout the year. However, for some thirty years, the presence of species has tended to become significantly extended throughout the year. During the 2001-2008 period, there was a noticeable decline and even a disappearance of the categories involved in sexual reproduction as well as those involved in parthenogenesis, in favor of non-breeding individuals.

  17. Comparison between symbolic and spectral analyses of short-term heart rate variability in a subsample of the ELSA-Brasil study.

    PubMed

    Dantas, Eduardo Miranda; Andreão, Rodrigo Varejão; da Silva, Valdo José Dias; Ribeiro, Antonio L P; Kemp, Andrew H; Brunoni, André R; Lotufo, Paulo A; Rodrigues, Sérgio L; Bensenor, Isabela M; Mill, José Geraldo

    2015-10-01

    Linear and nonlinear analyses of heart rate variability (HRV) have been largely used to evaluate the autonomic balance directed to the cardiovascular system. However, comparative studies evaluating the agreement between methods are scarce. Therefore, our aim was to examine the relationship between spectral (SPA; linear) and symbolic analyses (SYA; nonlinear) indexes. A subsample of 683 participants of the Brazilian Longitudinal Study of Adult Health was investigated. Linear and nonlinear analyses were obtained from 10 min ECG recording at rest. Reliability and agreement between methods were evaluated by kappa-statistic and proportion of agreement. According to SYA, the most frequent pattern was P1V (sympathovagal balance, without sympathetic or vagal predominance) comprising 62.7% of the sample, followed by P2V (vagal predominance) with 33.2%, and finally P0V pattern (sympathetic predominance) with 4.1%. Overall proportion of agreement between SYA and SPA was 39.68% (95% CI 0.360-0.433), with expected agreement by chance of 30.8%. Kappa value was 0.128 indicating a slight agreement between methods. Proportion of agreement was 7.93% (95% CI 0.032-0.126) for predominant sympathetic modulation, 10.39% (95% CI 0.075-0.132) for sympathovagal modulation, and 40.29% (95% CI 0.361-0.444) for parasympathetic modulation. Our data provide evidence for important differences between SPA and SYA on HRV analysis. More studies are needed to clarify the causes of disagreement between two methods designed to evaluate the autonomic modulation of heart beats. PMID:26333658

  18. Locked into Copenhagen pledges - Implications of short-term emission targets for the cost and feasibility of long-term climate goals

    SciTech Connect

    Riahi, Keywan; Kriegler, Elmar; Johnson, Nils; Bertram, Christoph; den Elzen, Michel; Eom, Jiyong; Schaeffer, Michiel; Edmonds, James A.; Isaac, Morna; Krey, Volker; Longden, Thomas; Luderer, Gunnar; Mejean, Aurelie; McCollum, David; Mima, Silvana; Turton, Hal; Van Vuuren, Detlef; Wada, Kenichi; Bosetti, Valentina; Capros, Pantelis; Criqui, Patrick; Hamdi-Cherif, Meriem; Kainuma, M.; Edenhofer, Ottmar

    2015-01-01

    This paper provides an overview of the AMPERE intermodeling comparison with focus on the implications of near-term policies for the costs and attainability of long-term climate objectives. Ten modeling teams participated in the project to explore the consequences of global emissions following the proposed policy stringency of the national pledges from the Copenhagen Accord and Cancún Agreements to 2030. Specific features compared to earlier assessments are the explicit consideration of near-term 2030 emissions targets as well as the systematic sensitivity analysis for the availability and potential of mitigation technologies. Our estimates show that a 2030 mitigation effort comparable to the pledges would result in a further "lock-in" of the energy system into fossil fuels and thus impede the required energy transformation to reach low greenhouse-gas stabilization levels (450ppm CO2e). Major implications include significant increases in mitigation costs, increased risk that low stabilization targets become unattainable, and reduced chances of staying below the proposed temperature change target of 2C. With respect to technologies, we find that following the pledge pathways to 2030 would narrow policy choices, and increases the risks that some currently optional technologies, such as nuclear or carbon capture and storage (CCS), will become "a must" by 2030.

  19. Monthly means of selected climate variables for 1985 - 1989

    NASA Technical Reports Server (NTRS)

    Schubert, S.; Wu, C.-Y.; Zero, J.; Schemm, J.-K.; Park, C.-K.; Suarez, M.

    1992-01-01

    Meteorologists are accustomed to viewing instantaneous weather maps, since these contain the most relevant information for the task of producing short-range weather forecasts. Climatologists, on the other hand, tend to deal with long-term means, which portray the average climate. The recent emphasis on dynamical extended-range forecasting and, in particular measuring and predicting short term climate change makes it important that we become accustomed to looking at variations on monthly and longer time scales. A convenient toll for researchers to familiarize themselves with the variability which occurs in selected parameters on these time scales is provided. The format of the document was chosen to help facilitate the intercomparison of various parameters and highlight the year-to-year variability in monthly means.

  20. Solar variability, weather, and climate

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Advances in the understanding of possible effects of solar variations on weather and climate are most likely to emerge by addressing the subject in terms of fundamental physical principles of atmospheric sciences and solar-terrestrial physis. The limits of variability of solar inputs to the atmosphere and the depth in the atmosphere to which these variations have significant effects are determined.

  1. Onboard Short Term Plan Viewer

    NASA Technical Reports Server (NTRS)

    Hall, Tim; LeBlanc, Troy; Ulman, Brian; McDonald, Aaron; Gramm, Paul; Chang, Li-Min; Keerthi, Suman; Kivlovitz, Dov; Hadlock, Jason

    2011-01-01

    Onboard Short Term Plan Viewer (OSTPV) is a computer program for electronic display of mission plans and timelines, both aboard the International Space Station (ISS) and in ISS ground control stations located in several countries. OSTPV was specifically designed both (1) for use within the limited ISS computing environment and (2) to be compatible with computers used in ground control stations. OSTPV supplants a prior system in which, aboard the ISS, timelines were printed on paper and incorporated into files that also contained other paper documents. Hence, the introduction of OSTPV has both reduced the consumption of resources and saved time in updating plans and timelines. OSTPV accepts, as input, the mission timeline output of a legacy, print-oriented, UNIX-based program called "Consolidated Planning System" and converts the timeline information for display in an interactive, dynamic, Windows Web-based graphical user interface that is used by both the ISS crew and ground control teams in real time. OSTPV enables the ISS crew to electronically indicate execution of timeline steps, launch electronic procedures, and efficiently report to ground control teams on the statuses of ISS activities, all by use of laptop computers aboard the ISS.

  2. Solar variability and Earth's climate

    NASA Astrophysics Data System (ADS)

    Rozelot, J. P.; Lefebvre, S.

    2003-04-01

    The purpose of this lecture is to investigate whether it is possible to found a solar signature on the Earth’s climatic changes over long period of times. Recent studies indicate that small but persistent variations in solar energy flux may play a role in climatic changes; one of the most important concerns are the changes in the irradiance. If it is known that the irradiance variability have an effect on the upper UV layers on the atmosphere of the Earth, the mechanisms that redistribute this variability on the lower layers, seat of the climate, are not well known. We will discuss here some aspects which are currently at the basis of some interesting scientific debates. The first one points out the irradiance modeling, for which it is not exclude that small variations (but temporally unrelenting) of the solar radius may contribute for a non negligible part of the irradiance changes. We will show how recent measurements of the solar shape (the helioid), well explained theoretically, affect solar luminosity models. Such valuable models of the irradiance are obviously valuable inputs on the stratosphere. To this respect, a remarkable new correlation, between irradiance and the stratospheric temperature, will be presented. The second point will address new indications of the solar origin in the total atmospheric angular momentum (AAM) of the entire Earth. It is not impossible that solar-AAM-climate connections are possible in modulating solar effects on flow interactions in the atmosphere. These could, for example, account for mechanisms by which climate system can amplify a weak solar input. In the last section of this lecture, we will present how future space measurements (PICARD satellite) will contribute to set up new insights into the problem of climate variability, mainly by accurately measuring the so-called W parameter (ratio between irradiance and diameter relative variations).

  3. Range expansion through fragmented landscapes under a variable climate

    PubMed Central

    Bennie, Jonathan; Hodgson, Jenny A; Lawson, Callum R; Holloway, Crispin TR; Roy, David B; Brereton, Tom; Thomas, Chris D; Wilson, Robert J

    2013-01-01

    Ecological responses to climate change may depend on complex patterns of variability in weather and local microclimate that overlay global increases in mean temperature. Here, we show that high-resolution temporal and spatial variability in temperature drives the dynamics of range expansion for an exemplar species, the butterfly Hesperia comma. Using fine-resolution (5 m) models of vegetation surface microclimate, we estimate the thermal suitability of 906 habitat patches at the species' range margin for 27 years. Population and metapopulation models that incorporate this dynamic microclimate surface improve predictions of observed annual changes to population density and patch occupancy dynamics during the species' range expansion from 1982 to 2009. Our findings reveal how fine-scale, short-term environmental variability drives rates and patterns of range expansion through spatially localised, intermittent episodes of expansion and contraction. Incorporating dynamic microclimates can thus improve models of species range shifts at spatial and temporal scales relevant to conservation interventions. PMID:23701124

  4. Downscaling climate variability associated with quasi-periodic climate signals: A new statistical approach using MSSA

    NASA Astrophysics Data System (ADS)

    Cañón, Julio; Domínguez, Francina; Valdés, Juan B.

    2011-02-01

    SummaryA statistical method is introduced to downscale hydroclimatic variables while incorporating the variability associated with quasi-periodic global climate signals. The method extracts statistical information of distributed variables from historic time series available at high resolution and uses Multichannel Singular Spectrum Analysis (MSSA) to reconstruct, on a cell-by-cell basis, specific frequency signatures associated with both the variable at a coarse scale and the global climate signals. Historical information is divided in two sets: a reconstruction set to identify the dominant modes of variability of the series for each cell and a validation set to compare the downscaling relative to the observed patterns. After validation, the coarse projections from Global Climate Models (GCMs) are disaggregated to higher spatial resolutions by using an iterative gap-filling MSSA algorithm to downscale the projected values of the variable, using the distributed series statistics and the MSSA analysis. The method is data adaptive and useful for downscaling short-term forecasts as well as long-term climate projections. The method is applied to the downscaling of temperature and precipitation from observed records and GCM projections over a region located in the US Southwest, taking into account the seasonal variability associated with ENSO.

  5. Short-term energy outlook, January 1999

    SciTech Connect

    1999-01-01

    The Energy Information Administration (EIA) prepares the Short-Term Energy Outlook (energy supply, demand, and price projections) monthly. The forecast period for this issue of the Outlook extends from January 1999 through December 2000. Data values for the fourth quarter 1998, however, are preliminary EIA estimates (for example, some monthly values for petroleum supply and disposition are derived in part from weekly data reported in EIA`s Weekly Petroleum Status Report) or are calculated from model simulations that use the latest exogenous information available (for example, electricity sales and generation are simulated by using actual weather data). The historical energy data, compiled in the January 1999 version of the Short-Term Integrated Forecasting System (STIFS) database, are mostly EIA data regularly published in the Monthly Energy Review, Petroleum Supply Monthly, and other EIA publications. Minor discrepancies between the data in these publications and the historical data in this Outlook are due to independent rounding. The STIFS model is driven principally by three sets of assumptions or inputs: estimates of key macroeconomic variables, world oil price assumptions, and assumptions about the severity of weather. Macroeconomic estimates are produced by DRI/McGraw-Hill but are adjusted by EIA to reflect EIA assumptions about the world price of crude oil, energy product prices, and other assumptions which may affect the macroeconomic outlook. By varying the assumptions, alternative cases are produced by using the STIFS model. 28 figs., 19 tabs.

  6. Solar Variability and Terrestrial Climate

    NASA Astrophysics Data System (ADS)

    Mörner, N.-A.

    The thermal conditions on Planet Earth are primarily the function of the energy in- put from the Sun. The variations in climate on Planet Earth is, however, primarily the function of the redistribution and reorganisation of the internal terrestrial heat balance. Solar variability may affect terrestrial climate (1) by direct changes in irradiance, a fac- tor, however, which is known to be very small, (2) by the solar wind interaction with the geomagnetic field increasing and decreasing the shielding capacity to infalling cosmic-ray, which is known to affect the formation of clouds thereby also affecting global terrestrial climat, and (3) by the solar wind interaction with the geomagnetic field leading to changes in the EarthSs rate of rotation which affect ocean and atmo- sphere circulation thereby also affecting global climate (and sea level). INTAS Project 97-301008 concerns the interaction between geomagnetic field changes and global climatic changes. No doubts, we see important links between externally and internally driven changes in the EarthSs geomagnetic field and changes in terrestrial climate.

  7. Diagnostic studies of climate variability

    SciTech Connect

    Bradley, R.S. ); Diaz, H.F. )

    1992-01-01

    This paper reports on the progress on the first year of the diagnostic studies of climate variability project. The objectives were as follows: to initiate studies of long-term climatic variability, using long instrumental data sets, and proxy records; to examine regional changes of temperature and precipitation over the past century in relation to changes at the hemispheric and global scale; and to produce a map-based archive of monthly and seasonal temperature, precipitation and pressure data fore display on PCs. Significant progress has been made in all of these areas. This paper summarizes results of the work accomplished. Part A summarizes results of the work accomplished. Part A summarizes the work accomplished primarily at the University of Massachusetts. Part B summarizes work primarily conducted at NOAA/ERL. A list of papers published, in press, or in preparation then follows. Appendix 1 is a description of the proposed research in 1992--93, and a proposed budget.

  8. Reanalyses and Essential Climate Variables

    NASA Technical Reports Server (NTRS)

    Bosilovich, Michael

    2011-01-01

    Reanalyses are a potentially powerful climate data collection driven by observations but also subjected to model bias. Additionally, reanalyses can produce and use essential climate variables in a consistent method. For example, snow cover and soil moisture (among other variables) will eventually be assimilated into the reanalyses, but also provide crucial validation data. Sea surface temperature can be prescribed or assimilated in a coupled reanalysis. The strength of reanalysis lies in the ancillary data that is produced from the modeling components but not routinely observed thereby providing more complete Earth system information. The weakness in this concept is that the model derived data can be affected by model bias and may also change relative to the available observing system. Here, we will review the status of existing reanalyses and the ECVs being considered for the workshop. Purpose of Michael Bosilovich's contribution to the workshop: Michael Bosilovich will represent US reanalysis community in this international discussion of Essential Climate Variables (ECVs) and the relative nature of reanalyses to ECVs.

  9. Climate variability and campylobacter infection: an international study

    NASA Astrophysics Data System (ADS)

    Sari Kovats, R.; Edwards, Sally J.; Charron, Dominique; Cowden, John; D'Souza, Rennie M.; Ebi, Kristie L.; Gauci, Charmaine; Gerner-Smidt, Peter; Hajat, Shakoor; Hales, Simon; Hernández Pezzi, Gloria; Kriz, Bohumir; Kutsar, Kuulo; McKeown, Paul; Mellou, Kassiani; Menne, Bettina; O'Brien, Sarah; Pelt, Wilfrid; Schmid, Hans

    2005-03-01

    Campylobacter is among the most important agents of enteritis in developed countries. We have described the potential environmental determinants of the seasonal pattern of infection with campylobacter in Europe, Canada, Australia and New Zealand. Specifically, we investigated the role of climate variability on laboratory-confirmed cases of campylobacter infection from 15 populations. Regression analysis was used to quantify the associations between timing of seasonal peaks in infection in space and time. The short-term association between weekly weather and cases was also investigated using Poisson regression adapted for time series data. All countries in our study showed a distinct seasonality in campylobacter transmission, with many, but not all, populations showing a peak in spring. Countries with milder winters have peaks of infection earlier in the year. The timing of the peak of infection is weakly associated with high temperatures 3 months previously. Weekly variation in campylobacter infection in one region of the UK appeared to be little affected by short-term changes in weather patterns. The geographical variation in the timing of the seasonal peak suggests that climate may be a contributing factor to campylobacter transmission. The main driver of seasonality of campylobacter remains elusive and underscores the need to identify the major serotypes and routes of transmission for this disease.

  10. Tropical deforestation and climate variability

    NASA Astrophysics Data System (ADS)

    Voldoire, A.; Royer, J. F.

    A new tropical deforestation experiment has been performed, with the ARPEGE-Climat atmospheric global circulation model associated with the ISBA land surface scheme. Simulations are forced with observed monthly mean sea surface temperatures and thus inter-annual variability of the ocean system is taken into account. The local mean response to deforestation over Amazonia and Africa is relatively weak compared with most published studies and compensation effects are particularly important. However, a large increase in daily maximum temperatures is obtained during the dry season when soil water stress dominates. The analysis of daily variability shows that the distributions of daily minimum and maximum temperatures are noticeably modified with an increase in extreme temperatures. Daily precipitation amounts also indicate a weakening of the convective activity. Conditions for the onset of convection are less frequently gathered, particularly over southern Amazonia and western equatorial Africa. At the same time, the intensity of convective events is reduced, especially over equatorial deforested regions. The inter-annual variability is also enhanced. For instance, El Niño events generally induce a large drying over northern Amazonia, which is well reproduced in the control simulation. In the deforested experiment, a positive feedback effect leads to a strong intensification of this drying and a subsequent increase in surface temperature. The change in variability as a response to deforestation can be more crucial than the change of the mean climate since more intense extremes could be more detrimental for agriculture than an increase in mean temperatures.

  11. Short-term intercultural psychotherapy: ethnographic inquiry.

    PubMed

    Seeley, Karen M

    2004-01-01

    This article examines the challenges specific to short-term intercultural treatments and recently developed approaches to intercultural treatments based on notions of cultural knowledge and cultural competence. The article introduces alternative approaches to short-term intercultural treatments based on ethnographic inquiry adapted for clinical practice. Such approaches allow clinicians conducting short-term intercultural treatments to foreground clients' indigenous conceptions of selfhood, mind, relationship, and emotional disturbance, and thus to more fully grasp their internal, interpersonal, and external worlds. This article demonstrates the uses of clinically adapted ethnographic inquiry in three short-term intercultural cases. PMID:14964524

  12. Interdecadal variability in surface climate during the instrumental period

    NASA Astrophysics Data System (ADS)

    Osborn, Timothy

    2016-04-01

    Although long-term warming of global mean temperature is robust across different observational datasets, there are interesting features at interdecadal timescales that deserve further investigation. A realistic characterisation of interdecadal variability is critical. It is required for important applications such as the detection and attribution of climate changes and assessment of data-model agreement. Via its role in the slowdown of warming relative to model simulations, interdecadal variability is one of the factors considered in the expert judgement (reported in the IPCC's fifth assessment) that near-term projections of warming are likely to be less than those simulated by the CMIP5 ensemble of climate models. This highlights its relevance to future projections of both forced change and unforced variability. Interdecadal variability in surface temperatures will be characterised according to their regional and latitudinal structures. Some features differ between datasets, reflecting the structural uncertainty arising from different choices made for addressing inhomogeneities in the observations and incomplete observational coverage, resulting in different degrees of spatial smoothness and completeness. Other features are robust between datasets, representing short-term forcings and unforced variability. The unforced variability is associated with changes in atmospheric circulation, and these changes also drive regional precipitation anomalies. It is informative, therefore, to represent them as modes of variability in circulation-temperature-precipitation "space", but complications arise from the limited coverage of observational data, especially in the 19th century. Changes in data coverage alter the empirical relationship between these climate variables and need to be taken into account when comparing, for example, the decadal trends around the large El Nino events in 1877-78 and 1997-8.

  13. Short-term variability in the dates of the Indian monsoon onset and retreat on the southern and northern slopes of the central Himalayas as determined by precipitation stable isotopes

    NASA Astrophysics Data System (ADS)

    Yu, Wusheng; Yao, Tandong; Tian, Lide; Ma, Yaoming; Wen, Rong; Devkota, Lochan P.; Wang, Weicai; Qu, Dongmei; Chhetri, Tek B.

    2016-07-01

    This project launched the first study to compare the stable isotopes (δ18O and δD) in daily precipitation at Kathmandu (located on the southern slope of the central Himalayas) and Tingri (located on the northern slope). The results show that low δ18O and δD values of summer precipitation at the two stations were closely related to intense convection of the Indian monsoon. However, summer δ18O and δD values at Tingri were lower than those at Kathmandu, a result of the lift effect of the Himalayas, coupled with convection disturbances and lower temperatures at Tingri. In winter, the relatively high δ18O and δD values at the two stations appears to have resulted from the influence of the westerlies. Compared with those during the summer, the subsidence of the westerlies and northerly winds resulted in relatively high δ18O and δD values of the winter precipitation at Tingri. Winter δ18O and δD values at Kathmandu far exceeded those at Tingri, due to more intense advection of the southern branch of the westerlies, and higher temperatures and relative humidity at Kathmandu. The detailed differences in stable isotopes between the two stations follow short-term variability in the onset date of the Indian monsoon and its retreat across the central Himalayas. During the sampling period, the Indian monsoon onset at Tingri occurred approximately 1 week later than that at Kathmandu. However, the retreat at Tingri began roughly 3 days earlier. Clearly, the duration of the Indian monsoon effects last longer at Kathmandu than that at Tingri. Our findings also indicate that the India monsoon travels slowly northward across the central Himalayas due to the blocking of the Himalayas, but retreats quickly.

  14. Short-term energy outlook, April 1999

    SciTech Connect

    1999-04-01

    The forecast period for this issue of the Outlook extends from April 1999 through December 2000. Data values for the first quarter 1999, however, are preliminary EIA estimates (for example, some monthly values for petroleum supply and disposition are derived in part from weekly data reported in EIA`s Weekly Petroleum Status Report) or are calculated from model simulations that use the latest exogenous information available (for example, electricity sales and generation are simulated by using actual weather data). The historical energy data, compiled in the April 1999 version of the Short-Term Integrated forecasting system (STIFS) database, are mostly EIA data regularly published in the Monthly Energy Review, Petroleum Supply Monthly, and other EIA publications. Minor discrepancies between the data in these publications and the historical data in this Outlook are due to independent rounding. The STIFS model is driven principally by three sets of assumptions or inputs: estimates of key macroeconomic variables, world oil price assumptions, and assumptions about the severity of weather. Macroeconomic estimates are produced by DRI/McGraw-Hill but are adjusted by EIA to reflect EIA assumptions about the world price of crude oil, energy product prices, and other assumptions which may affect the macroeconomic outlook. By varying the assumptions, alternative cases are produced by using the STIFS model. 25 figs., 19 tabs.

  15. Short-term Drought Prediction in India.

    NASA Astrophysics Data System (ADS)

    Shah, R.; Mishra, V.

    2014-12-01

    Medium range soil moisture drought forecast helps in decision making in the field of agriculture and water resources management. Part of skills in medium range drought forecast comes from precipitation. Proper evaluation and correction of precipitation forecast may improve drought predictions. Here, we evaluate skills of ensemble mean precipitation forecast from Global Ensemble Forecast System (GEFS) for medium range drought predictions over India. Climatological mean (CLIM) of historic data (OBS) are used as reference forecast to evaluate GEFS precipitation forecast. Analysis was conducted based on forecast initiated on 1st and 15th dates of each month for lead up to 7-days. Correlation and RMSE were used to estimate skill scores of accumulated GEFS precipitation forecast from lead 1 to 7-days. Volumetric indices based on the 2X2 contingency table were used to check missed and falsely predicted historic volume of daily precipitation from GEFS in different regions and at different thresholds. GEFS showed improvement in correlation of 0.44 over CLIM during the monsoon season and 0.55 during the winter season. Lower RMSE was showed by GEFS than CLIM. Ratio of RMSE in GEFS and CLIM comes out as 0.82 and 0.4 (perfect skill is at zero) during the monsoon and winter season, respectively. We finally used corrected GEFS forecast to derive the Variable Infiltration Capacity (VIC) model, which was used to develop short-term forecast of hydrologic and agricultural (soil moisture) droughts in India.

  16. Climatic Variability over the North Atlantic

    NASA Astrophysics Data System (ADS)

    Hurrell, J.; Hoerling, M. P.; Folland, C. K.

    INTRODUCTION WHAT IS THE NORTH ATLANTIC OSCILLATION AND HOW DOES IT IMPACT REGIONAL - CLIMATE? WHAT ARE THE MECHANISMS THAT GOVERN NORTH ATLANTIC OSCILLATION VARIABILITY? Atmospheric Processes Ocean Forcing of the Atmosphere CONCLUDING COMMENTS ON THE OTHER ASPECTS OF NORTH ATLANTIC CLIMATE - VARIABILITY REFERENCES

  17. Climate variability and vulnerability to climate change: a review.

    PubMed

    Thornton, Philip K; Ericksen, Polly J; Herrero, Mario; Challinor, Andrew J

    2014-11-01

    The focus of the great majority of climate change impact studies is on changes in mean climate. In terms of climate model output, these changes are more robust than changes in climate variability. By concentrating on changes in climate means, the full impacts of climate change on biological and human systems are probably being seriously underestimated. Here, we briefly review the possible impacts of changes in climate variability and the frequency of extreme events on biological and food systems, with a focus on the developing world. We present new analysis that tentatively links increases in climate variability with increasing food insecurity in the future. We consider the ways in which people deal with climate variability and extremes and how they may adapt in the future. Key knowledge and data gaps are highlighted. These include the timing and interactions of different climatic stresses on plant growth and development, particularly at higher temperatures, and the impacts on crops, livestock and farming systems of changes in climate variability and extreme events on pest-weed-disease complexes. We highlight the need to reframe research questions in such a way that they can provide decision makers throughout the food system with actionable answers, and the need for investment in climate and environmental monitoring. Improved understanding of the full range of impacts of climate change on biological and food systems is a critical step in being able to address effectively the effects of climate variability and extreme events on human vulnerability and food security, particularly in agriculturally based developing countries facing the challenge of having to feed rapidly growing populations in the coming decades. PMID:24668802

  18. Climate variability and vulnerability to climate change: a review

    PubMed Central

    Thornton, Philip K; Ericksen, Polly J; Herrero, Mario; Challinor, Andrew J

    2014-01-01

    The focus of the great majority of climate change impact studies is on changes in mean climate. In terms of climate model output, these changes are more robust than changes in climate variability. By concentrating on changes in climate means, the full impacts of climate change on biological and human systems are probably being seriously underestimated. Here, we briefly review the possible impacts of changes in climate variability and the frequency of extreme events on biological and food systems, with a focus on the developing world. We present new analysis that tentatively links increases in climate variability with increasing food insecurity in the future. We consider the ways in which people deal with climate variability and extremes and how they may adapt in the future. Key knowledge and data gaps are highlighted. These include the timing and interactions of different climatic stresses on plant growth and development, particularly at higher temperatures, and the impacts on crops, livestock and farming systems of changes in climate variability and extreme events on pest-weed-disease complexes. We highlight the need to reframe research questions in such a way that they can provide decision makers throughout the food system with actionable answers, and the need for investment in climate and environmental monitoring. Improved understanding of the full range of impacts of climate change on biological and food systems is a critical step in being able to address effectively the effects of climate variability and extreme events on human vulnerability and food security, particularly in agriculturally based developing countries facing the challenge of having to feed rapidly growing populations in the coming decades. PMID:24668802

  19. Short-term energy outlook: Methodology

    NASA Astrophysics Data System (ADS)

    Cornett, C.; Paxson, D.; Reznek, A. P.; Chu, C.; Sitzer, S.; Gamson, N.; Childress, J. P.; Paul, S.; Weigel, H.; Sutton, S.

    1981-05-01

    Detailed discussions of forecasting methodology and analytical topics concerning short-term energy markets are presented. Major assumptions necessary to make the energy forecasts are also discussed. Supplementary analyses of topics related to short-term energy forecasting are also given. The discussions relate to the forecasts prepared using the short term integrated forecasting system. This set of computer models uses data from various sources to develop energy supply and demand balances. Econmetric models used to predict the demand for petroleum products, natural gas, coal, and electricity are discussed. Price prediction models are also discussed. The role of oil inventories in world oil markets is reviewed. Various relationship between weather patterns and energy consumption are discussed.

  20. Theoretical models of synaptic short term plasticity

    PubMed Central

    Hennig, Matthias H.

    2013-01-01

    Short term plasticity is a highly abundant form of rapid, activity-dependent modulation of synaptic efficacy. A shared set of mechanisms can cause both depression and enhancement of the postsynaptic response at different synapses, with important consequences for information processing. Mathematical models have been extensively used to study the mechanisms and roles of short term plasticity. This review provides an overview of existing models and their biological basis, and of their main properties. Special attention will be given to slow processes such as calcium channel inactivation and the effect of activation of presynaptic autoreceptors. PMID:23626536

  1. Timing of climate variability and grassland productivity

    PubMed Central

    Craine, Joseph M.; Nippert, Jesse B.; Elmore, Andrew J.; Skibbe, Adam M.; Hutchinson, Stacy L.; Brunsell, Nathaniel A.

    2012-01-01

    Future climates are forecast to include greater precipitation variability and more frequent heat waves, but the degree to which the timing of climate variability impacts ecosystems is uncertain. In a temperate, humid grassland, we examined the seasonal impacts of climate variability on 27 y of grass productivity. Drought and high-intensity precipitation reduced grass productivity only during a 110-d period, whereas high temperatures reduced productivity only during 25 d in July. The effects of drought and heat waves declined over the season and had no detectable impact on grass productivity in August. If these patterns are general across ecosystems, predictions of ecosystem response to climate change will have to account not only for the magnitude of climate variability but also for its timing. PMID:22331914

  2. Mesoscale flows and climate variability

    NASA Astrophysics Data System (ADS)

    Ólafsson, Haraldur; Pálmason, Bolli; Vary, Anne; Schettino, Camille; Thomas, Aurelien; Nína Petersen, Guðrún; Ágústsson, Hálfdán

    2016-04-01

    Thermally driven mesoscale flows, in particular the sea breeze, and their importance for the climate of a mid-latitude island is assessed by observations from Iceland and numerical simulations over idealized and real topography. Subsequently, an extended summertime period is simulated with surface conditions that correspond to current climate as well as surface conditions that are plausible in a future warmer climate with increased vegetation. A change in the albedo and the Bowen ratio results in changes in the sea breeze, leading to mean temperature changes whose magnitude is more than half the predicted temperature increase in the 21st Century by some GCMs.

  3. Improving Reproductive Performance: Long and Short Term

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improvements in reproductive performance for beef herds can be classified as short term (current year) or long term (lifetime production) and can be applied to and measured in individual animals or the entire herd. In other species, results show that rearing young animals under caloric restriction ...

  4. Spanish: Familiarization and Short-Term Training.

    ERIC Educational Resources Information Center

    Arbelaez, Vicente; And Others

    The State Department's Foreign Service Institute short-term, intensive course in Spanish language and culture for government employees going to work in Spanish-speaking countries contains an introductory section and 38 lessons and 10 related audio cassettes intended as the basis for a ten-week program with an instructor. The lessons cover these…

  5. Metropolitan French: Familiarization & Short-Term Training.

    ERIC Educational Resources Information Center

    Iszkowski, Marie-Charlotte

    The U.S. Department of State's Foreign Service Institute French Familiarization and Short-Term (FAST) course for personnel working and living in France consists of 10 weeks of French language instruction combined with practical and cultural information. An introductory section outlines FAST course objectives and sample teaching techniques in…

  6. Short-Term Play Therapy for Children.

    ERIC Educational Resources Information Center

    Kaduson, Heidi Gerard, Ed.; Schaefer, Charles E., Ed.

    Play therapy offers a powerful means of helping children resolve a wide range of psychological difficulties, and many play approaches are ideally suited to short-term work. This book brings together leading play therapists to share their expertise on facilitating children's healing in a shorter time frame. The book provides knowledge and skills…

  7. Short-Term Study Abroad, 2001: IIE's Complete Guide to Summer and Short-Term Study.

    ERIC Educational Resources Information Center

    O'Sullivan, Marie, Ed.

    This guide, formerly called "Vacation Study Abroad," lists short-term educational programs of varying lengths from 1 week to several months. Offerings are for the winter and spring breaks, the summer, and other short-term intervals. Some 60% of these programs are sponsored by U.S. accredited colleges and universities. The guide also offers…

  8. Processes Understanding of Decadal Climate Variability

    NASA Astrophysics Data System (ADS)

    Prömmel, Kerstin; Cubasch, Ulrich

    2016-04-01

    The realistic representation of decadal climate variability in the models is essential for the quality of decadal climate predictions. Therefore, the understanding of those processes leading to decadal climate variability needs to be improved. Several of these processes are already included in climate models but their importance has not yet completely been clarified. The simulation of other processes requires sometimes a higher resolution of the model or an extension by additional subsystems. This is addressed within one module of the German research program "MiKlip II - Decadal Climate Predictions" (http://www.fona-miklip.de/en/) with a focus on the following processes. Stratospheric processes and their impact on the troposphere are analysed regarding the climate response to aerosol perturbations caused by volcanic eruptions and the stratospheric decadal variability due to solar forcing, climate change and ozone recovery. To account for the interaction between changing ozone concentrations and climate a computationally efficient ozone chemistry module is developed and implemented in the MiKlip prediction system. The ocean variability and air-sea interaction are analysed with a special focus on the reduction of the North Atlantic cold bias. In addition, the predictability of the oceanic carbon uptake with a special emphasis on the underlying mechanism is investigated. This addresses a combination of physical, biological and chemical processes.

  9. Binding in short-term visual memory.

    PubMed

    Wheeler, Mary E; Treisman, Anne M

    2002-03-01

    The integration of complex information in working memory, and its effect on capacity, shape the limits of conscious cognition. The literature conflicts on whether short-term visual memory represents information as integrated objects. A change-detection paradigm using objects defined by color with location or shape was used to investigate binding in short-term visual memory. Results showed that features from the same dimension compete for capacity, whereas features from different dimensions can be stored in parallel. Binding between these features can occur, but focused attention is required to create and maintain the binding over time, and this integrated format is vulnerable to interference. In the proposed model, working memory capacity is limited both by the independent capacity of simple feature stores and by demands on attention networks that integrate this distributed information into complex but unified thought objects. PMID:11900102

  10. Interference with visual short-term memory.

    PubMed

    Logie, R H; Zucco, G M; Baddeley, A D

    1990-10-01

    Working memory (Baddeley and Hitch 1974) incorporates the notion of a visuo-spatial sketch pad; a mechanism thought to be specialized for short-term storage of visuo-spatial material. However, the nature and characteristics of this hypothesized mechanism are as yet unclear. Two experiments are reported which examined selective interference in short-term visual memory. Experiment 1 contrasted recognition memory span for visual matrix patterns with that for visually presented letter sequences. These two span tasks were combined with concurrent arithmetic or a concurrent task which involved manipulation of visuo-spatial material. Results suggested that although there was a small, significant disruption by concurrent arithmetic of span for the matrix patterns, there was a substantially larger disruption of the letter span task. The converse was true for the secondary visuo-spatial task. Experiment 2 combined the span tasks with two established tasks developed by Brooks (1967). Span for matrix patterns was disrupted by a visuo-spatial task but not by a secondary verbal task. The converse was true for letter span. These results suggest that the impairment in short-term visual memory resulting from secondary arithmetic reflects a small general processing load, but that the selective interference due to mode of processing is by far the stronger effect. Results are interpreted as being entirely consistent with the notion of a specialized visuo-spatial mechanism in working memory. PMID:2260493

  11. Impacts of Climate Change and Climate Variability on Hydrological Regimes

    NASA Astrophysics Data System (ADS)

    van Dam, Jan C.

    2003-10-01

    Water is going to be one of the key, if not the most critical, environmental issues in the twenty-first century because of the escalation in socio-economic pressures on the environment in general. Any future climate change or climate variability will only accentuate such pressures. This volume initially follows the perspective of the Intergovernmental Panel on Climate Change (IPCC) to infer possible changes in hydrological regimes and water quality based on the outputs from various scenarios of General Circulation Models (GCMs). In subsequent chapters, the possible effects of climate change on the hydrology of each of the continents is examined. The book concludes with an overview of hydrological models for use in the evaluation of the impacts of climate change. It will provide a valuable guide for environmental planners and policy-makers, and will also be of use to all students and researchers interested in the possible effects of climate change.

  12. Chaos, dynamical structure and climate variability

    SciTech Connect

    Stewart, H.B.

    1995-09-01

    Deterministic chaos in dynamical systems offers a new paradigm for understanding irregular fluctuations. Techniques for identifying deterministic chaos from observed data, without recourse to mathematical models, are being developed. Powerful methods exist for reconstructing multidimensional phase space from an observed time series of a single scalar variable; these methods are invaluable when only a single scalar record of the dynamics is available. However, in some applications multiple concurrent time series may be available for consideration as phase space coordinates. Here the authors propose some basic analytical tools for such multichannel time series data, and illustrate them by applications to a simple synthetic model of chaos, to a low-order model of atmospheric circulation, and to two high-resolution paleoclimate proxy data series. The atmospheric circulation model, originally proposed by Lorenz, has 27 principal unknowns; they establish that the chaotic attractor can be embedded in a subspace of eight dimensions by exhibiting a specific subset of eight unknowns which pass multichannel tests for false nearest neighbors. They also show that one of the principal unknowns in the 27-variable model--the global mean sea surface temperature--is of no discernible usefulness in making short-term forecasts.

  13. Short-term energy outlook: Quarterly projections, fourth quarter 1997

    SciTech Connect

    1997-10-14

    The Energy Information Administration (EIA) prepares quarterly short-term energy supply, demand, and price projections for printed publication in January, April, July, and October in the Short-Term Energy Outlook. The details of these projections, as well as monthly updates on or about the 6th of each interim month, are available on the internet at: www.eia.doe.gov/emeu/steo/pub/contents.html. The forecast period for this issue of the Outlook extends from the fourth quarter of 1997 through the fourth quarter of 1998. Values for the fourth quarter of 1997, however, are preliminary EIA estimates (for example, some monthly values for petroleum supply and disposition are derived in part from weekly data reported in EIA`s Weekly Petroleum Status Report) or are calculated from model simulations that use the latest exogenous information available (for example, electricity sales and generation are simulated by using actual weather data). The historical energy data, compiled in the fourth quarter 1997 version of the Short-Term Integrated Forecasting System (STIFS) database, are mostly EIA data regularly published in the Monthly Energy Review, Petroleum Supply Monthly, and other EIA publications. Minor discrepancies between the data in these publications and the historical data in this Outlook are due to independent rounding. The STIFS model is driven principally by three sets of assumptions or inputs: estimates of key macroeconomic variables, world oil price assumptions, and assumptions about the severity of weather. 19 tabs.

  14. Short-term energy outlook, July 1998

    SciTech Connect

    1998-07-01

    The Energy Information Administration (EIA) prepares The Short-Term Energy Outlook (energy supply, demand, and price projections) monthly for distribution on the internet at: www.eia.doe.gov/emeu/steo/pub/contents.html. In addition, printed versions of the report are available to subscribers in January, April, July and October. The forecast period for this issue of the Outlook extends from July 1998 through December 1999. Values for second quarter of 1998 data, however, are preliminary EIA estimates (for example, some monthly values for petroleum supply and disposition are derived in part from weekly data reported in EIA`s Weekly Petroleum Status Report) or are calculated from model simulations that use the latest exogenous information available (for example, electricity sales and generation are simulated by using actual weather data). The historical energy data, compiled in the July 1998 version of the Short-Term Integrated Forecasting System (STIFS) database, are mostly EIA data regularly published in the Monthly Energy Review, Petroleum Supply Monthly, and other EIA publications. Minor discrepancies between the data in these publications and the historical data in this Outlook are due to independent rounding. 28 figs., 19 tabs.

  15. Prospects for Improved Forecasts of Weather and Short-Term Climate Variability on Subseasonal (2-Week to 2-Month) Times Scales

    NASA Technical Reports Server (NTRS)

    Schubert, Siegfried; Dole, Randall; vandenDool, Huug; Suarez, Max; Waliser, Duane

    2002-01-01

    This workshop, held in April 2002, brought together various Earth Sciences experts to focus on the subseasonal prediction problem. While substantial advances have occurred over the last few decades in both weather and seasonal prediction, progress in improving predictions on these intermediate time scales (time scales ranging from about two weeks to two months) has been slow. The goals of the workshop were to get an assessment of the "state of the art" in predictive skill on these time scales, to determine the potential sources of "untapped" predictive skill, and to make recommendations for a course of action that will accelerate progress in this area. One of the key conclusions of the workshop was that there is compelling evidence for predictability at forecast lead times substantially longer than two weeks. Tropical diabatic heating and soil wetness were singled out as particularly important processes affecting predictability on these time scales. Predictability was also linked to various low-frequency atmospheric "phenomena" such as the annular modes in high latitudes (including their connections to the stratosphere), the Pacific/North American (PNA) pattern, and the Madden Julian Oscillation (MJO). The latter, in particular, was highlighted as a key source of untapped predictability in the tropics and subtropics, including the Asian and Australian monsoon regions.

  16. Climatic Variability In Tropical Countries

    NASA Astrophysics Data System (ADS)

    Seneviratne, L. W.

    2003-04-01

    atmospheric condition and hence reduces rainfall for about 1.5 years in tropical countries. This was proved in 2001. This forecast was presented as a paper in 1998 Stockholm Water Symposium. The results were true for Brazil as well. The danger is now over when the episode is relaxed. Second half of 2002 was heavily wet and all the tanks in Sri Lanka except Kirindioya complex in Hambanthoa area got filled. This condition was seen in 1997 where all tanks got filled. El Nino analysts declared 1997 as a drought year as the previous year had experienced warming in Pacific Ocean. Southern Oscillation events are now dissociating to conformity. Discussion Hambanthoa District remained in the dry zone of Sri Lanka for 2000 years as the soil forms expressed as reddish brown earths. Original kingdoms had its base in Anuradhapura in Northcentral Province and Magama in Hambanthota district. Tools used by contemporary farmers were not powerful to use enormous water resources in wet zone. A system of diversion dams and use of run of the river irrigation has proved as the main criteria of that era. Diversion dams and canal projects were in existence. The diversion dams with special shape was mistaken by british surveyors and marked as broken dams in plans. DLOMendis later identified these as effective deflecting dams. The purpose was to wet the area to do cultivation. This system of wetting the land was suitable for dry climates with low rainfall. High technology was introduced by Irrigation Department to construct several reservoirs in Hambanthota. This was planned after the insufficient water use of Ellagala anicut from Kirindi Oya. Next step was to plan a reservoir project at Lunugamvehera dam site. Precipitation data available for 50 years were studied and a reservoir was designed for 20 000acres of paddy. It was planned to cultivate rice for Maha season and other field crops for Yala season. Cultivation commenced in 1985 and the farmers had enough water for 20000acres including

  17. Weather variability, climatic change, and soybean production

    SciTech Connect

    Thompson, L.M.

    1985-01-01

    A crop/weather model was used to determine the effect of changing climate and weather variability on soybean production in the Corn Belt. A cooling trend from the 1930s to the 1970s was accompanied by an upward trend in July plus August rainfall. There was decreased weather variability from the 1930s to 1973 and greatly increased weather variability after 1973. Improved weather from 1930 to 1972 increased soybean yields 3 bushels/acre. Higher intensity rainfalls increased in Illinois and Iowa after 1970.

  18. Economics of solar energy: Short term costing

    NASA Astrophysics Data System (ADS)

    Klee, H.

    The solar economics based on life cycle costs are refuted as both imaginary and irrelevant. It is argued that predicting rates of inflation and fuel escalation, expected life, maintenance costs, and legislation over the next ten to twenty years is pure guesswork. Furthermore, given the high mobility level of the U.S. population, the average consumer is skeptical of long run arguments which will pay returns only to the next owners. In the short term cost analysis, the house is sold prior to the end of the expected life of the system. The cash flow of the seller and buyer are considered. All the relevant factors, including the federal tax credit and the added value of the house because of the solar system are included.

  19. Paleohydrology reconstruction and Holocene climate variability in the South Adriatic Sea

    NASA Astrophysics Data System (ADS)

    Siani, G.; Magny, M.; Paterne, M.; Debret, M.; Fontugne, M.

    2012-09-01

    Holocene paleohydrology reconstruction was derived combining planktic and benthic stable oxygen and carbon isotopes, sea surface temperatures (SSTs) and oxygen isotope composition of seawater (δ18Ow) from a high sedimentation core collected in the south Adriatic sea (SAS). Chronology of core is based on 10 AMS 14C measures on planktic foraminifera and tephra markers. Results reveal two contrasted paleohydrological periods that reflect (i) a marked lowering of δ 18Ow/salinity during the early to middle Holocene (11.5 ka to 6.3 ka), including the two-steps sapropel S1 deposition, followed during the middle to upper Holocene by (ii) a prevailed period of increased salinity and enhanced arid conditions in the south Adriatic basin. Superimposed on these trends, short-term centennial-scale hydrological events punctuated the Holocene period in the SAS. During the Early to Middle Holocene, a short-term SST cooling together with a prominent δ 18Ow/salinity lowering, more pronounced than during the sapropel S1 phase, delineates the sapropel S1 interruption. This short interval, coeval to the 8.2 ka event, is also distinguished by a resumption of deep-water convection in the SAS as indicated by stable isotope reconstruction on benthic forminifera. After 6 ka, centennial-scale δ18Ow and G. bulloides δ13C lowering, mostly centered between 3 to 0.6 ka, reflect short term hydrological changes related to a more intensive Po river runoff. These short-term events, even of lesser amplitude compared to the early to middle Holocene period, may have induced a lowering of sea surface density and consequently reduced and/or inhibited the formation of deep bottom waters in the SAS. Comparison of the emerging centennial to millennial-scale hydrological record with previous climatic records from the central Mediterranean area and north of the Alps revealed possible synchronicities (within the radiocarbon-dating uncertainty) between phases of lower salinity in SAS and periods of wetter

  20. Inferring climate variability from skewed proxy records

    NASA Astrophysics Data System (ADS)

    Emile-Geay, J.; Tingley, M.

    2013-12-01

    Many paleoclimate analyses assume a linear relationship between the proxy and the target climate variable, and that both the climate quantity and the errors follow normal distributions. An ever-increasing number of proxy records, however, are better modeled using distributions that are heavy-tailed, skewed, or otherwise non-normal, on account of the proxies reflecting non-normally distributed climate variables, or having non-linear relationships with a normally distributed climate variable. The analysis of such proxies requires a different set of tools, and this work serves as a cautionary tale on the danger of making conclusions about the underlying climate from applications of classic statistical procedures to heavily skewed proxy records. Inspired by runoff proxies, we consider an idealized proxy characterized by a nonlinear, thresholded relationship with climate, and describe three approaches to using such a record to infer past climate: (i) applying standard methods commonly used in the paleoclimate literature, without considering the non-linearities inherent to the proxy record; (ii) applying a power transform prior to using these standard methods; (iii) constructing a Bayesian model to invert the mechanistic relationship between the climate and the proxy. We find that neglecting the skewness in the proxy leads to erroneous conclusions and often exaggerates changes in climate variability between different time intervals. In contrast, an explicit treatment of the skewness, using either power transforms or a Bayesian inversion of the mechanistic model for the proxy, yields significantly better estimates of past climate variations. We apply these insights in two paleoclimate settings: (1) a classical sedimentary record from Laguna Pallcacocha, Ecuador (Moy et al., 2002). Our results agree with the qualitative aspects of previous analyses of this record, but quantitative departures are evident and hold implications for how such records are interpreted, and

  1. Climate variation explains a third of global crop yield variability

    PubMed Central

    Ray, Deepak K.; Gerber, James S.; MacDonald, Graham K.; West, Paul C.

    2015-01-01

    Many studies have examined the role of mean climate change in agriculture, but an understanding of the influence of inter-annual climate variations on crop yields in different regions remains elusive. We use detailed crop statistics time series for ~13,500 political units to examine how recent climate variability led to variations in maize, rice, wheat and soybean crop yields worldwide. While some areas show no significant influence of climate variability, in substantial areas of the global breadbaskets, >60% of the yield variability can be explained by climate variability. Globally, climate variability accounts for roughly a third (~32–39%) of the observed yield variability. Our study uniquely illustrates spatial patterns in the relationship between climate variability and crop yield variability, highlighting where variations in temperature, precipitation or their interaction explain yield variability. We discuss key drivers for the observed variations to target further research and policy interventions geared towards buffering future crop production from climate variability. PMID:25609225

  2. Short-term energy outlook. Quarterly projections, first quarter 1996

    SciTech Connect

    1996-02-01

    The Energy Information Administration (EIA) prepares quarterly, short-term energy supply, demand, and price projections for publication in February, May, August, and November in the Outlook. The forecast period for this issue of the Outlook extends from the first quarter of 1996 through the fourth quarter of 1997. Values for the fourth quarter of 1995, however, are preliminary EIA estimates (for example, some monthly values for petroleum supply and disposition are derived in part from weekly data reported in the Weekly Petroleum Status Report) or are calculated from model simulations using the latest exogenous information available (for example, electricity sales and generation are simulated using actual weather data). The historical energy data, compiled into the first quarter 1996 version of the Short-Term Integrated Forecasting System (STIFS) database, are mostly EIA data regularly published in the Monthly Energy Review, Petroleum Supply Monthly, and other EIA publications. Minor discrepancies between the data in these publications and the historical data in this Outlook are due to independent rounding. The STIFS database is archived quarterly and is available from the National Technical Information Service. The cases are produced using the Short-Term Integrated Forecasting System (STIFS). The STIFS model is driven principally by three sets of assumptions or inputs: estimates of key macroeconomic variables, world oil price assumptions, and assumptions about the severity of weather. Macroeconomic estimates are produced by DRI/McGraw-Hill but are adjusted by EIA to reflect EIA assumptions about the world price of crude oil, energy product prices, and other assumptions which may affect the macroeconomic outlook.

  3. Short-term energy outlook: Quarterly projections, second quarter 1997

    SciTech Connect

    1997-04-01

    The Energy Information Administration (EIA) prepares quarterly short-term energy supply, demand, and price projections for publication in January, April, July, and October in the Outlook. The forecast period for this issue of the Outlook extends from the second quarter of 1997 through the fourth quarter of 1998. Values for the first quarter of 1997, however, are preliminary EIA estimates (for example, some monthly values for petroleum supply and disposition are derived in part from weekly data reported in EIA`s Weekly Petroleum Status Report) or are calculated from model simulations that use the latest exogenous information available (for example, electricity sales and generation are simulated by using actual weather data). The historical energy data, compiled in the second quarter 1997 version of the Short-Term Integrated Forecasting System (STIFS) database, are mostly EIA data regularly published in the Monthly Energy Review, Petroleum Supply Monthly, and other EIA publications. Minor discrepancies between the data in these publications and the historical data in this Outlook are due to independent rounding. The STIFS database is archived quarterly and is available from the National Technical Information Service. The STIFS model is driven principally by three sets of assumptions or inputs: estimates of key macroeconomic variables, world oil price assumptions, and assumptions about the severity of weather. Macroeconomic estimates are produced by DRI/McGraw-Hill but are adjusted by EIA to reflect EIA assumptions about the world price of crude oil, energy product prices, and other assumptions which may affect the macroeconomic outlook. By varying the assumptions, alternative cases are produced by using the Short-Term Integrated Forecasting System (STIFS). 34 figs., 19 tabs.

  4. Short-Term Energy Outlook Model Documentation: Macro Bridge Procedure to Update Regional Macroeconomic Forecasts with National Macroeconomic Forecasts

    EIA Publications

    2010-01-01

    The Regional Short-Term Energy Model (RSTEM) uses macroeconomic variables such as income, employment, industrial production and consumer prices at both the national and regional1 levels as explanatory variables in the generation of the Short-Term Energy Outlook (STEO). This documentation explains how national macroeconomic forecasts are used to update regional macroeconomic forecasts through the RSTEM Macro Bridge procedure.

  5. Prioritizing Global Observations Along Essential Climate Variables

    NASA Astrophysics Data System (ADS)

    Bojinski, Stephan; Richter, Carolin

    2010-12-01

    The Global Climate Observing System (GCOS) Secretariat, housed within the World Meteorological Organization, released in August 2010 updated guidance for priority actions worldwide in support of observations of GCOS Essential Climate Variables (ECVs). This guidance states that full achievement of the recommendations in the 2010 Implementation Plan for the Global Observing System for Climate in Support of the UNFCCC (http://www.wmo.int/pages/prog/gcos/Publications/gcos­138.pdf) is required to ensure that countries are able to understand and predict climate change and its impacts and manage their response throughout the 21st century and beyond. GCOS is sponsored by the United Nations and the International Council for Science (ICSU) and is an internationally coordinated network of observing systems and a program of activities that support and improve the network, which is designed to meet evolving national and international requirements for climate observations. One of the main objectives of GCOS is to sustain observations into the future to allow evaluation of how climate is changing, so that informed decisions can be made on prevention, mitigation, and adaptation strategies. GCOS priorities are based on the belief that observations are crucial to supporting the research needed to refine understanding of the climate system and its changes, to initialize predictions on time scales out to decades, and to develop the models used to make these predictions and longer­term scenario-based projections. Observations are also needed to assess social and economic vulnerabilities and to support related actions needed across a broad range of societal sectors by underpinning emerging climate services.

  6. Short-term energy outlook quarterly projections. First quarter 1994

    SciTech Connect

    Not Available

    1994-02-07

    The Energy Information Administration (EIA) prepares quarterly, short- term energy supply, demand, and price projections for publication in February, May, August, and November in the Short-Term Energy Outlook (Outlook). An annual supplement analyzes the performance of previous forecasts, compares recent cases with those of other forecasting services, and discusses current topics related to the short-term energy markets.

  7. Group Processes in Short-Term Group Therapy of Psychotics.

    ERIC Educational Resources Information Center

    Opalic, Peter

    1990-01-01

    Presents fundamental principles of short-term psychotherapy in reference to psychotic patients. Emphasizes empirical hermeneutical research into group process within the phenomenological approach. Presents case study of short-term psychotherapy with psychotic patients. Outlines four-stage approach to short-term therapy. (Author/ABL)

  8. In Search of Decay in Verbal Short-Term Memory

    ERIC Educational Resources Information Center

    Berman, Marc G.; Jonides, John; Lewis, Richard L.

    2009-01-01

    Is forgetting in the short term due to decay with the mere passage of time, interference from other memoranda, or both? Past research on short-term memory has revealed some evidence for decay and a plethora of evidence showing that short-term memory is worsened by interference. However, none of these studies has directly contrasted decay and…

  9. Space-time structure of climate variability

    NASA Astrophysics Data System (ADS)

    Laepple, Thomas; Reschke, Maria; Huybers, Peter; Rehfeld, Kira

    2016-04-01

    The spatial scale of climate variability is closely linked to the temporal scale. Whereas fast variations such as weather are regional, glacial-interglacial cycles appear to be globally coherent. Quantifying the relationship between local and large-scale climate variations is essential for mapping the extent of past climate changes. Larger spatial scales of climate variations on longer time scales are expected if one views the atmosphere and oceans as primarily diffusive with respect to heat. On the other hand, the interaction of a dynamical system with spatially variable boundary conditions --- for example: topography, gradients in insolation, and variations in rotational effects --- will lead to spatially heterogeneous structures that are largely independent of time scale. It has been argued that the increase in spatial scales continues across all time scales [Mitchell, 1976], but up to now, the space-time structure of variations beyond the decadal scale is basically unexplored. Here, we attempt to estimate the spatial extent of temperature changes up to millennial time-scales using instrumental observations, paleo-observations and climate model simulations. Although instrumental and climate model data show an increase in spatial scale towards slower variations, paleo-proxy data, if interpreted as temperature signals, lead to ambiguous results. An analysis of a global Holocene stack [Marcott et al., 2013], for example, suggests a jump towards more localized patterns when leaving the instrumental time scale. Localization contradicts physical expectations and may instead reflect the presence of various types of noise. Turning the problem around, and imposing a consistent space-time structure across instruments and proxy records allows us to constrain the interpretation of the climate signal in proxy records. In the case of the Holocene stack, preliminary results suggest that the time-uncertainty on the Holocene records would have to be much larger than published in

  10. Continuity of Landsat observations: Short term considerations

    USGS Publications Warehouse

    Wulder, M.A.; White, Joanne C.; Masek, J.G.; Dwyer, J.; Roy, D.P.

    2011-01-01

    As of writing in mid-2010, both Landsat-5 and -7 continue to function, with sufficient fuel to enable data collection until the launch of the Landsat Data Continuity Mission (LDCM) scheduled for December of 2012. Failure of one or both of Landsat-5 or -7 may result in a lack of Landsat data for a period of time until the 2012 launch. Although the potential risk of a component failure increases the longer the sensor's design life is exceeded, the possible gap in Landsat data acquisition is reduced with each passing day and the risk of Landsat imagery being unavailable diminishes for all except a handful of applications that are particularly data demanding. Advances in Landsat data compositing and fusion are providing opportunities to address issues associated with Landsat-7 SLC-off imagery and to mitigate a potential acquisition gap through the integration of imagery from different sensors. The latter will likely also provide short-term, regional solutions to application-specific needs for the continuity of Landsat-like observations. Our goal in this communication is not to minimize the community's concerns regarding a gap in Landsat observations, but rather to clarify how the current situation has evolved and provide an up-to-date understanding of the circumstances, implications, and mitigation options related to a potential gap in the Landsat data record. ?? 2010.

  11. Short-term GNSS satellite clock stability

    NASA Astrophysics Data System (ADS)

    Griggs, E.; Kursinski, E. R.; Akos, D.

    2015-08-01

    Global Navigation Satellite System (GNSS) clock stability is characterized via the modified Allan deviation using active hydrogen masers as the receiver frequency reference. The high stability of the maser reference allows the GNSS clock contribution to the GNSS carrier phase variance to be determined quite accurately. Satellite clock stability for four different GNSS constellations are presented, highlighting the similarities and differences between the constellations as well as satellite blocks and clock types. Impact on high-rate applications, such as GNSS radio occultation (RO), is assessed through the calculation of the maximum carrier phase error due to clock instability. White phase noise appears to dominate at subsecond time scales. However, while we derived the theoretical contribution of white phase modulation to the modified Allan deviation, our analysis of the GNSS satellite clocks was limited to 1-200 s time scales because of inconsistencies between the subsecond results from the commercial and software-defined receivers. The rubidium frequency standards on board the Global Positioning System (GPS) Block IIF, BeiDou, and Galileo satellites show improved stability results in comparison to previous GPS blocks for time scales relevant to RO. The Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) satellites are the least stable of the GNSS constellations in the short term and will need high-rate corrections to produce RO results comparable to those from the other GNSS constellations.

  12. Advances in Understanding Decadal Climate Variability

    NASA Technical Reports Server (NTRS)

    Busalacchi, Antonio J.

    1999-01-01

    Recently, a joint Brazil-France-U.S. program, known as PIRATA (Pilot Research moored Array in the Tropical Atlantic), was proposed to begin the deployment of moored measurement platforms in the tropical Atlantic in order to enhance the existing observational data base and subsequent understanding of the processes by which the ocean and atmosphere couple in key regions of the tropical Atlantic Ocean. Empirical studies have suggested that there are strong relationships between tropical Atlantic upper ocean variability, SST, ocean-atmosphere coupling and regional climate variability. During the early 1980's a coordinated set of surface wind, subsurface thermal structure, and subsurface current observations were obtained as part of the U.S.-France SEQUAL-FOCAL process experiment designed to observe the seasonal response of the tropical Atlantic Ocean to surface forcing. Since that time, however, the observational data base for the tropical Atlantic Ocean has disintegrated to a few ship-tracks measuring ocean temperatures and a small collection of tide gauge stations measuring sea level. A more comprehensive set of observations, modeling and empirical studies is now in order to make progress on understanding the regional climate variability. The proposed PIRATA program will use mooring platforms similar to the tropical Pacific Ocean TAO array to measure surface fluxes of momentum and heat and the corresponding changes in the upper ocean thermal structure. It is anticipated that the oceanic data from this monitoring array will also be used in a predictive mode for initialization studies of regional coupled climate models. Of particular interest are zonal and meridional modes of ocean-atmosphere variability within the tropical Atlantic basin that have significant impacts on the regional climate of the bordering continents.

  13. Advances in Understanding Decadal Climate Variability

    NASA Technical Reports Server (NTRS)

    Busalaacchi, Antonio J.

    1998-01-01

    Recently, a joint Brazil-France-U.S. program, known as PIRATA (Pilot Research moored Array in the Tropical Atlantic), was proposed to begin the deployment of moored measurement platforms in the tropical Atlantic in order to enhance the existing observational data base and subsequent understanding of the processes by which the ocean and atmosphere couple in key regions of the tropical Atlantic Ocean. Empirical studies have suggested that there are strong relationships between tropical Atlantic upper ocean variability, SST, ocean-atmosphere coupling and regional climate variability. During the early 1980's a coordinated set of surface wind, subsurface thermal structure, and subsurface current observations were obtained as part of the U.S.-France SEQUAL- FOCAL process experiment designed to observe the seasonal response of the tropical Atlantic Ocean to surface forcing. Since that time, however, the observational data base for the tropical Atlantic Ocean has disintegrated to a few shiptracks measuring ocean temperatures and a small collection of tide gauge stations measuring sea level. A more comprehensive set of observations, modeling and empirical studies is now in order to make progress on understanding the regional climate variability. The proposed PIRATA program will use mooring platforms similar to the tropical Pacific Ocean TAO array to measure surface fluxes of momentum and heat and the corresponding changes in the upper ocean thermal structure. It is anticipated that the oceanic data from this monitoring array will also be used in a predictive mode for initialization studies of regional coupled climate models. Of particular interest are zonal and meridional modes of ocean-atmosphere variability within the tropical Atlantic basin that have significant impacts on the regional climate of the bordering continents.

  14. Predictability of Pacific Decadal Climate Variability and Climate Impacts (Invited)

    NASA Astrophysics Data System (ADS)

    Newman, M.

    2013-12-01

    Predictability of Pacific sea surface temperature (SST) climate variations and climate impacts on time scales of 1-10 years is discussed, using a global linear inverse model (LIM) as an empirical benchmark for decadal surface temperature forecast skill. Constructed from the observed simultaneous and 1-yr lag covariability statistics of annually averaged sea surface temperature (SST) and surface (2 m) land temperature global anomalies during 1901-2009, the LIM has hindcast skill for leads of 2-5 yr and 6-9 yr comparable to and sometimes even better than skill of the phase 5 of the Coupled Model Intercomparison Project (CMIP5) model hindcasts initialized annually over the period 1960-2000 and has skill far better than damped persistence (e.g., a local univariate AR1 process). Pronounced similarity in geographical variations of skill between LIM and CMIP5 hindcasts suggests similarity in their sources of skill as well, supporting additional evaluation of LIM predictability. For forecast leads above 1-2 yr, LIM skill almost entirely results from three nonorthogonal patterns: one corresponding to the secular trend and two more, each with about 10-yr decorrelation time scales but no trend, that represent most of the predictable portions of the Atlantic multidecadal oscillation (AMO) and Pacific decadal oscillation (PDO) indices, respectively. In contrast, for forecasts greater than about two years, ENSO acts as noise and degrades forecast skill. These results suggest that current coupled model decadal forecasts may not yet have much skill beyond that captured by multivariate, predictably linear dynamics. A particular focus will be on the predictability of the PDO, which represents the dominant mode of Pacific decadal SST variability. The PDO is shown to represent a few different physical processes, including wind-driven changes of SSTs that can occur either due to daily weather variability or to tropical forcing, and variations in the North Pacific western boundary

  15. Les fluctuations à court terme du climat et l'interprétation des observations récentes en terme d'effet de serreShort-term climatic fluctuations and the interprétation of récent observations in terms of greenhouse effect

    NASA Astrophysics Data System (ADS)

    André, Jean-Claude; Royer, Jean-François

    1999-02-01

    Simulations of future climate made with coupled general circulation models of the atmosphere and ocean predict that the increase of the concentration of greenhouse gases released in the atmosphere by man's activities will have a large influence on the climate of the next century. The identification of the climatic impact produced by the rapid increase in carbon dioxide concentration in the last decades is made difficult by strong interannual climate variability, and requires the application of statistical techniques combining several climatic indicators (method of climatic "fingerprints") so as to improve the detection of a possible anthropogenic perturbation. In this paper we review the evolution through the last decades of several climate indicators showing global warming, its geographical distribution, sea level, the hydrological cycle and the response of vegetation, and we compare them to the model results predicted in climate scenarios. The coherence between model results and observed climatic trends shows that the additional greenhouse effect is starting to become detectable in recent climatic data.

  16. Multiscale Variability of the Monsoon Climate

    NASA Astrophysics Data System (ADS)

    Krishnamurthy, V.

    2005-05-01

    The reliability of weather forecasts is limited to a few days and is mainly determined by the synoptic scale features of the atmosphere. The predictability of weather models depends on the error growth determined by nonlinear terms representing advection. Smaller scale features, such as convection, may also influence the predictability of the synoptic scale forecasts. While the prediction of instantaneous states of the system may be impossible on longer time scale, there is optimism for medium-range and long-range forecasts of time-averaged features of the climate system. Such optimism is based on the observation that slowly-varying boundary forces such as sea surface temperature, soil moisture and snow influence the variability of the atmosphere on a longer time scale, especially in the tropical region. This study discusses the variability of such a tropical climate system, the monsoon, and shows that its variability consists of a combination of large-scale persistent seasonal mean component and intraseasonal variability of different time scales. The spatial variability of these components is also found to consist of different scales. By performing multi-channel singular spectrum analysis of daily rainfall, low-pressure systems, outgoing long-wave radiation and winds, two oscillatory modes with periods of about 45 and 20 days have been identified and shown to correspond to the active and break phases of the monsoon. These two intraseasonal modes, however, do not contribute much to the seasonal mean rainfall. Three other components of the MSSA are identified as the contributors to the seasonal mean rainfall, possibly arising from the influence of slowly-varying boundary forces. The prospect for making accurate long-range forecasts of the monsoon depends on the relative magnitudes of the large-scale seasonally persistent component and the intraseasonal component and on climate model experiments to establish a relation between the two components.

  17. Seletracetam enhances short term depression in vitro.

    PubMed

    Yang, Xiaofeng; Meehan, Anna L; Rothman, Steven M; Dubinsky, Janet M

    2015-11-01

    Seletracetam (SEL), an analog of the antiepileptic drug levetiracetam (LEV), decreases seizure activity in a number of epilepsy models and binds to the synaptic vesicle protein SV2A with a higher affinity than LEV. Experiments were performed to determine if SEL, like LEV, reduces the later EPSPs in long trains of stimuli in a manner dependent upon access to the interior of synaptic vesicles and SV2A binding. When hippocampal slices were incubated in 3-30μM SEL for 3h, but not 30 min, the relative amplitude of the CA1 field excitatory synaptic potentials decreased over the course of a train of high frequency stimuli more than for control slices. This short term depression was frequency and dose dependent and largely disappeared when the spontaneous activity during the loading period was removed by cutting the Schaffer collaterals. The SEL effect was also observed in slices loaded during prolonged stimulation at 1Hz, but not 10Hz. Hippocampal slices loaded with both SEL and FM1-43 to visualize synaptic boutons released the FM1-43 in response to prolonged stimulation much more slowly than control slices during prolonged stimulation. Like LEV, SEL produced a frequency-dependent decrement of synaptic transmission that was dependent upon the drug entering recycling synaptic vesicles and compatible with SV2A binding. Previous observations of SV2A binding affinity correlated with the current effect of SEL and the previously reported effect of LEV on synaptic transmission validate SV2A as an extremely attractive target for future antiepileptic drug development. PMID:26320080

  18. Solar Variability in the Context of Other Climate Forcing Mechanisms

    NASA Technical Reports Server (NTRS)

    Hansen, James E.

    1999-01-01

    I compare and contrast climate forcings due to solar variability with climate forcings due to other mechanisms of climate change, interpretation of the role of the sun in climate change depends upon climate sensitivity and upon the net forcing by other climate change mechanisms. Among the potential indirect climate forcings due to solar variability, only that due to solar cycle induced ozone changes has been well quantified. There is evidence that the sun has been a significant player in past climate change on decadal to century time scales, and that it has the potential to contribute to climate change in the 21st century.

  19. Linking Large-scale, Long-term Modeling and Micro-scale, Short-term Process Studies to Assess Climate-driven Changes in Hydrological Dynamics in the Nam Co Basin, Tibet, China

    NASA Astrophysics Data System (ADS)

    Biskop, S.; Krause, P.; Leiterer, R.; Helmschrot, J.

    2010-12-01

    The Tibetan Plateau, often called the third pole, is considered as one of the most vulnerable regions being affected by global climate change. Since little knowledge is given on the effect of changing monsoon dynamics, temperature increase and increasing glacier melt on the Tibetan hydrology, a project was initiated to study their spatio-temporal impact on the regional water balance. As shown by the remote sensing based analysis of lake extent and lake level changes, the increase of the lake level of the Nam Co (30°N/90°E, 4718 m a.s.l.) in the previous decades indicates that the Nam Co basin (10 800 km2) located in central Tibet is experiencing noticeable changes in the hydrological dynamics. To quantify those changes, the distributed, hydrological model J2000 which was adapted to high-altitude conditions and extended by a glacier and a lake module. Given the limited data availability gridded global and regional climate projections (ECHAM5, CRU, APHRODITE, TRMM) were compared with measured climate data from the Nam Co station and nearby stations and processed as climate input data for the hydrological modeling. Land cover derived from Landsat data, soil information (ISRIC-World Soil Information) and topographic information were overlaid to receive spatial model entities according to the Hydrological Response Units approach. Using field-based data on soil and vegetation patterns and characteristics as well as soil moisture measurements, micro-scale process studies were performed to derive parameters and knowledge for the calibration of the model. With the model spatially distributed estimates of precipitation, potential and actual evapotranspiration from the land surface and the lake itself, glacier and snow melt and runoff generation could be obtained for the period of 1961 in 2010 in monthly and daily time steps. Comparisons with the very rarely available measured hydrological quantities showed a reasonable correlation. For example, observed lake level rise

  20. Variable temperature seat climate control system

    DOEpatents

    Karunasiri, Tissa R.; Gallup, David F.; Noles, David R.; Gregory, Christian T.

    1997-05-06

    A temperature climate control system comprises a variable temperature seat, at least one heat pump, at least one heat pump temperature sensor, and a controller. Each heat pump comprises a number of Peltier thermoelectric modules for temperature conditioning the air in a main heat exchanger and a main exchanger fan for passing the conditioned air from the main exchanger to the variable temperature seat. The Peltier modules and each main fan may be manually adjusted via a control switch or a control signal. Additionally, the temperature climate control system may comprise a number of additional temperature sensors to monitor the temperature of the ambient air surrounding the occupant as well as the temperature of the conditioned air directed to the occupant. The controller is configured to automatically regulate the operation of the Peltier modules and/or each main fan according to a temperature climate control logic designed both to maximize occupant comfort during normal operation, and minimize possible equipment damage, occupant discomfort, or occupant injury in the event of a heat pump malfunction.

  1. Inter-daily variability of a strong thermally-driven wind system over the Atacama Desert of South America: synoptic forcing and short-term predictability using the GFS global model

    NASA Astrophysics Data System (ADS)

    Jacques-Coper, Martín; Falvey, Mark; Muñoz, Ricardo C.

    2015-07-01

    Crucial aspects of a strong thermally-driven wind system in the Atacama Desert in northern Chile during the extended austral winter season (May-September) are studied using 2 years of measurement data from the Sierra Gorda 80-m meteorological mast (SGO, 22° 56' 24″ S; 69° 7' 58″ W, 2,069 m above sea level (a.s.l.)). Daily cycles of atmospheric variables reveal a diurnal (nocturnal) regime, with northwesterly (easterly) flow and maximum mean wind speed of 8 m/s (13 m/s) on average. These distinct regimes are caused by pronounced topographic conditions and the diurnal cycle of the local radiative balance. Wind speed extreme events of each regime are negatively correlated at the inter-daily time scale: High diurnal wind speed values are usually observed together with low nocturnal wind speed values and vice versa. The associated synoptic conditions indicate that upper-level troughs at the coastline of southwestern South America reinforce the diurnal northwesterly wind, whereas mean undisturbed upper-level conditions favor the development of the nocturnal easterly flow. We analyze the skill of the numerical weather model Global Forecast System (GFS) in predicting wind speed at SGO. Although forecasted wind speeds at 800 hPa do show the diurnal and nocturnal phases, observations at 80 m are strongly underestimated by the model. This causes a pronounced daily cycle of root-mean-squared error (RMSE) and bias in the forecasts. After applying a simple Model Output Statistics (MOS) post-processing, we achieve a good representation of the wind speed intra-daily and inter-daily variability, a first step toward reducing the uncertainties related to potential wind energy projects in the region.

  2. Short-Term Periodicities in Solar Indices

    NASA Astrophysics Data System (ADS)

    Kane, R. P.

    2005-03-01

    The purpose of the present communication is to identify the short-term (few tens of months) periodicities of several solar indices (sunspot number, Caii area and K index, Lyman α, 2800 MHz radio emission, coronal green-line index, solar magnetic field). The procedure used was: from the 3-month running means (3m) the 37-month running means (37m) were subtracted, and the factor (3m - 37m) was examined for several parameters. For solar indices, considerable fluctuations were seen during the ± 4 years around sunspot maxima of cycles 18-23, and virtually no fluctuations were seen in the ± 2 years around sunspot minima. The spacings between successive peaks were irregular but common for various solar indices. Assuming that there are stationary periodicities, a spectral analysis was carried out which indicated periodicities of months: 5.1 5.7, 6.2 7.0, 7.6 7.9, 8.9 9.6, 10.4 12.0, 12.8 13.4, 14.5 17.5, 22 25, 28 (QBO), 31 36 (QBO), 41 47 (QTO). The periodicities of 1.3 year (15.6 months) and 1.7 years (20.4 months) often mentioned in the literature were seen neither often nor prominently. Other periodicities occurred more often and more prominently. For the open magnetic flux estimated by Wang, Lean, and Sheeley (2000) and Wang and Sheeley (2002), it was noticed that the variations were radically different at different solar latitudes. The open flux for < 45∘ solar latitudes had variations very similar (parallel) to the sunspot cycle, while open flux for > 45∘ solar latitudes had variations anti-parallel to the sunspot cycle. The open fluxes, interplanetary magnetic field and cosmic rays, all showed periodicities similar to those of solar indices. Many peaks (but not all) matched, indicating that the open flux for < 45∘ solar latitudes was at least partially an adequate carrier of the solar characteristics to the interplanetary space and thence for galactic cosmic ray modulation.

  3. Climate variability and Port wine quality

    NASA Astrophysics Data System (ADS)

    Gouveia, Celia; Liberato, Margarida L. R.; Trigo, Ricardo M.; Dacamara, Carlos

    2010-05-01

    ), suggesting that this type of analysis may be used in developing a tool that may help anticipating a vintage year, based on already available seasonal climate outlooks. Célia Gouveia and Ricardo M. Trigo. "Influence of climate variability on wheat production in Portugal". GeoENV2006- 6th International Conference on Geostatistics for Environmental Applications, Rhodes, October, 25-27, 2006 Miranda, P.M.A., F. Coelho, A. R. Tomé, M. A Valente., A. Carvalho, C. Pires, H. O. Pires, V. C. Cabrinha and C. Ramalho (2002) "20th Century Portuguese Climate and Climate Scenarios", in Santos, F.D., K Forbes and R. Moita (eds) Climate Change in Portugal: Scenarios, Impacts and Adptation Measures", 27-83. Gradiva

  4. Climate Variability and Yields of Major Staple Food Crops in Northern Ghana

    NASA Astrophysics Data System (ADS)

    Amikuzuno, J.

    2012-12-01

    Climate variability, the short-term fluctuations in average weather conditions, and agriculture affect each other. Climate variability affects the agroecological and growing conditions of crops and livestock, and is recently believed to be the greatest impediment to the realisation of the first Millennium Development Goal of reducing poverty and food insecurity in arid and semi-arid regions of developing countries. Conversely, agriculture is a major contributor to climate variability and change by emitting greenhouse gases and reducing the agroecology's potential for carbon sequestration. What however, is the empirical evidence of this inter-dependence of climate variability and agriculture in Sub-Sahara Africa? In this paper, we provide some insight into the long run relationship between inter-annual variations in temperature and rainfall, and annual yields of the most important staple food crops in Northern Ghana. Applying pooled panel data of rainfall, temperature and yields of the selected crops from 1976 to 2010 to cointegration and Granger causality models, there is cogent evidence of cointegration between seasonal, total rainfall and crop yields; and causality from rainfall to crop yields in the Sudano-Guinea Savannah and Guinea Savannah zones of Northern Ghana. This suggests that inter-annual yields of the crops have been influenced by the total mounts of rainfall in the planting season. Temperature variability over the study period is however stationary, and is suspected to have minimal effect if any on crop yields. Overall, the results confirm the appropriateness of our attempt in modelling long-term relationships between the climate and crop yield variables.

  5. Risk Quantification for ANN Based Short-Term Load Forecasting

    NASA Astrophysics Data System (ADS)

    Iwashita, Daisuke; Mori, Hiroyuki

    A new risk assessment method for short-term load forecasting is proposed. The proposed method makes use of an Artificial Neural Network (ANN) to forecast one-step ahead daily maximum loads and evaluate uncertainty of in load forecasting. As ANN the model, the Radial Basis Function (RBF) network is employed to forecast loads due to the good performance. Sufficient realistic pseudo-scenarios are required to carry out quantitative risk analysis. The multivariate normal distribution with the correlation between input variables is used to give more realistic results to ANN. In addition, the method of Moment Matching is used to improve the accuracy of the multivariate normal distribution. The Peak Over Threshold (POT) approach is used to evaluate risk that exceeds the upper bounds of generation capacity. The proposed method is successfully applied to real data of daily maximum load forecasting.

  6. Use of continuous water quality records for hydrograph separation and to assess short-term variability and extremes in acidity and dissolved carbon dioxide for the River Dee, Scotland.

    PubMed

    Jarvie, H P; Neal, C; Smart, R; Owen, R; Fraser, D; Forbes, I; Wade, A

    2001-01-29

    A combination of continuous (15-min) pH, conductivity and temperature measurements and fortnightly spot-sampled water quality data were used to examine temporal variability and extremes in river water quality in an upland Scottish river: the River Dee at Mar Lodge. An empirical relationship was established for Gran-alkalinity by multiple regression against flow and conductivity for the fortnightly data. Applying this relationship to the continuous data, an estimate of continuous Gran-alkalinity was calculated. The continuous Gran-alkalinity record was used as (1) a conservative tracer in a simple two-component mixing model to determine the relative proportions of near-surface runoff and deeper groundwater contributing to stream flow; (2) to deconvolute the contribution of weathering and sea-salt contributions to stream conductivity; and (3) to calculate the excess partial pressure of carbon dioxide in stream water. The episodic variations in pH, weathering and sea-salt conductivity and excess partial pressures of carbon dioxide (EpCO2) associated with high flow events in the River Dee suggest that hydrological pathways play an important role in determining stream chemistry. The results of the hydrograph separation indicate that groundwater provides an important contribution to stream flow, and that there are large and hydrologically active stores of groundwater within the upper River Dee catchment. Sea-salts have an important influence on stream conductivity, particularly with the onset of storm runoff following summer drought periods. This suggests that sea-salts are concentrated in the upper soil horizons by dry deposition and/or evapotranspiration. EpCO2 behaves non-conservatively and shows marked diurnal variability under low-flow conditions during summer, inducing diurnal pH variations, and indicating the importance of within-river biological processes. This study emphasises the very intermittent nature of water quality extremes with stream spates and the

  7. Local-scale spatial modelling for interpolating climatic temperature variables to predict agricultural plant suitability

    NASA Astrophysics Data System (ADS)

    Webb, Mathew A.; Hall, Andrew; Kidd, Darren; Minansy, Budiman

    2016-05-01

    Assessment of local spatial climatic variability is important in the planning of planting locations for horticultural crops. This study investigated three regression-based calibration methods (i.e. traditional versus two optimized methods) to relate short-term 12-month data series from 170 temperature loggers and 4 weather station sites with data series from nearby long-term Australian Bureau of Meteorology climate stations. The techniques trialled to interpolate climatic temperature variables, such as frost risk, growing degree days (GDDs) and chill hours, were regression kriging (RK), regression trees (RTs) and random forests (RFs). All three calibration methods produced accurate results, with the RK-based calibration method delivering the most accurate validation measures: coefficients of determination ( R 2) of 0.92, 0.97 and 0.95 and root-mean-square errors of 1.30, 0.80 and 1.31 °C, for daily minimum, daily maximum and hourly temperatures, respectively. Compared with the traditional method of calibration using direct linear regression between short-term and long-term stations, the RK-based calibration method improved R 2 and reduced root-mean-square error (RMSE) by at least 5 % and 0.47 °C for daily minimum temperature, 1 % and 0.23 °C for daily maximum temperature and 3 % and 0.33 °C for hourly temperature. Spatial modelling indicated insignificant differences between the interpolation methods, with the RK technique tending to be the slightly better method due to the high degree of spatial autocorrelation between logger sites.

  8. Paleohydrology reconstruction and Holocene climate variability in the South Adriatic Sea

    NASA Astrophysics Data System (ADS)

    Siani, G.; Magny, M.; Paterne, M.; Debret, M.; Fontugne, M.

    2013-02-01

    Holocene paleohydrology reconstruction is derived combining planktonic and benthic stable oxygen and carbon isotopes, sea surface temperatures (SSTs) and oxygen isotope composition of seawater (δ18Ow) from a high sedimentation core collected in the South Adriatic Sea (SAS). Core chronology is based on 10 AMS 14C measures on planktonic foraminifera and tephra layers. Results reveal two contrasted paleohydrological periods that reflect (i) a marked lowering of δ18Ow/salinity during the early to mid-Holocene (11.5 ka to 6.3 ka), including the two-step sapropel S1 deposition, followed during the mid- to upper Holocene by (ii) a prevailing period of increased salinity and enhanced arid conditions in the South Adriatic Basin. Superimposed on these trends, short-term centennial-scale hydrological events punctuated the Holocene period in the SAS. During the early to mid-Holocene, two main SST coolings together with prominent δ18Ow/salinity lowering delineate the sapropel S1 interruption and the post-sapropel phase between 7.3 to 6.3 ka. After 6 ka, centennial-scale δ18Ow and G. bulloides δ13C lowering, mostly centered between 3 to 0.6 ka, reflect short-term hydrological changes related to more intensive runoff of the Po and/or Apennine rivers. These short-term events, even of lesser amplitude compared to the early to mid-Holocene period, may have induced a lowering of sea surface density and consequently reduced and/or inhibited the formation of deep bottom waters in the SAS. Comparison of the emerging centennial- to millennial-scale hydrological record with previous climatic records from the central Mediterranean area and north of the Alps reveal possible synchronicities (within the radiocarbon-dating uncertainty) between phases of lower salinity in the SAS and periods of wetter climatic conditions around the north-central Adriatic Sea. Finally, wavelet analyses provide new clues about the potential origin of climate variability in the SAS, confirming the evidence

  9. Short-term variability during an anchor station study in the southern Benguela upwelling system: Abundance, distribution and estimated production of mesozooplankton with special reference to Calanoides carinatus (Krøyer, 1849)

    NASA Astrophysics Data System (ADS)

    Verheye, Hans M.

    Daytime zooplankton samples collected at a fixed station position in St Helena Bay during a 27-day time series in March-April 1987 were used to describe the variability in the vertical distribution, abundance and population age structure of Calanoides carinatus in response to upwelling-related processes, and to provide an estimate of their production. The vertical distribution of C. carinatus was characterized by ontogenetic layering of copepodites and adults. The thermocline delimited the maximum depth of young copepodites (CI-CIII). Older stages avoided low-oxygen (<1ml O 2l -1) bottom water. C. carinatus was usually not associated with the chlorophyll a maximum. The spatial segregation of young and older stages is briefly discussed in relation to differential feeding habits and diel vertical migration behaviour. The demographic structure of the C. carinatus population showed evidence of a stable age distribution of copepodites and adults during the first of two upwelling cycles observed during the study. Overall mean abundance was 360 animals m -3. However, during the second upwelling cycle their mean abundance was reduced to 183 animals m -3 and adults dominated the population by 54%. These changes in abundance and age structure are discussed in relation to upwelling-induced advective processes. Surface-dwelling young copepodites (CI-CIII) are thought to be transported away from the study site, while re-seeding of the reduced nearshore population probably took place through advection of diapausal pre-adults (CV) in the upwelled water. Daily production of juvenile C. carinatus was estimated at 0.7 mg C m -3d -1 which, combined with an egg production of 1.0mg C m -3d -1 by addult females, is equivalent to 2% of the observed daily primary production. The mean P:B ratio for the copepodite stages was 0.167d -1. The role of this dominant copepod and the mesozooplankton in the carbon budget in St Helena Bay is discussed. Consumption by mesozooplankters was estimated

  10. Regression based modeling of vegetation and climate variables for the Amazon rainforests

    NASA Astrophysics Data System (ADS)

    Kodali, A.; Khandelwal, A.; Ganguly, S.; Bongard, J.; Das, K.

    2015-12-01

    Both short-term (weather) and long-term (climate) variations in the atmosphere directly impact various ecosystems on earth. Forest ecosystems, especially tropical forests, are crucial as they are the largest reserves of terrestrial carbon sink. For example, the Amazon forests are a critical component of global carbon cycle storing about 100 billion tons of carbon in its woody biomass. There is a growing concern that these forests could succumb to precipitation reduction in a progressively warming climate, leading to release of significant amount of carbon in the atmosphere. Therefore, there is a need to accurately quantify the dependence of vegetation growth on different climate variables and obtain better estimates of drought-induced changes to atmospheric CO2. The availability of globally consistent climate and earth observation datasets have allowed global scale monitoring of various climate and vegetation variables such as precipitation, radiation, surface greenness, etc. Using these diverse datasets, we aim to quantify the magnitude and extent of ecosystem exposure, sensitivity and resilience to droughts in forests. The Amazon rainforests have undergone severe droughts twice in last decade (2005 and 2010), which makes them an ideal candidate for the regional scale analysis. Current studies on vegetation and climate relationships have mostly explored linear dependence due to computational and domain knowledge constraints. We explore a modeling technique called symbolic regression based on evolutionary computation that allows discovery of the dependency structure without any prior assumptions. In symbolic regression the population of possible solutions is defined via trees structures. Each tree represents a mathematical expression that includes pre-defined functions (mathematical operators) and terminal sets (independent variables from data). Selection of these sets is critical to computational efficiency and model accuracy. In this work we investigate

  11. Short-term energy outlook. Quarterly projections, Third quarter 1994

    SciTech Connect

    Not Available

    1994-08-02

    The Energy Information Administration (EIA) prepares quarterly, short-term energy supply, demand, and price projections for publication in February, May, August, and November in the Short-Term Energy Outlook (Outlook). An annual supplement analyzes the performance of previous forecasts, compares recent cases with those of other forecasting services, and discusses current topics related to the short-term energy markets. (See Short-Term Energy Outlook Annual Supplement, DOE/EIA-0202). The feature article for this issue is Demand, Supply and Price Outlook for Reformulated Gasoline, 1995.

  12. Online Impact Prioritization of Essential Climate Variables on Climate Change

    NASA Astrophysics Data System (ADS)

    Forsythe-Newell, S. P.; Barkstrom, B. B.; Roberts, K. P.

    2007-12-01

    The National Oceanic & Atmospheric Administration (NOAA)'s NCDC Scientific Data Stewardship (SDS) Team has developed an online prototype that is capable of displaying the "big picture" perspective of all Essential Climate Variable (ECV) impacts on society and value to the IPCC. This prototype ECV-Model provides the ability to visualize global ECV information with options to drill down in great detail. It offers a quantifiable prioritization of ECV impacts that potentially may significantly enhance collaboration with respect to dealing effectively with climate change. The ECV-Model prototype assures anonymity and provides an online input mechanism for subject matter experts and decision makers to access, review and submit: (1) ranking of ECV"s, (2) new ECV's and associated impact categories and (3) feedback about ECV"s, satellites, etc. Input and feedback are vetted by experts before changes or additions are implemented online. The SDS prototype also provides an intuitive one-stop web site that displays past, current and planned launches of satellites; and general as well as detailed information in conjunction with imagery. NCDC's version 1.0 release will be available to the public and provide an easy "at-a-glance" interface to rapidly identify gaps and overlaps of satellites and associated instruments monitoring climate change ECV's. The SDS version 1.1 will enhance depiction of gaps and overlaps with instruments associated with In-Situ and Satellites related to ECVs. NOAA's SDS model empowers decision makers and the scientific community to rapidly identify weaknesses and strengths in monitoring climate change ECV's and potentially significantly enhance collaboration.

  13. Climate variability and extremes, interacting with nitrogen storage, amplify eutrophication risk

    NASA Astrophysics Data System (ADS)

    Lee, Minjin; Shevliakova, Elena; Malyshev, Sergey; Milly, P. C. D.; Jaffé, Peter R.

    2016-07-01

    Despite 30 years of basin-wide nutrient-reduction efforts, severe hypoxia continues to be observed in the Chesapeake Bay. Here we demonstrate the critical influence of climate variability, interacting with accumulated nitrogen (N) over multidecades, on Susquehanna River dissolved nitrogen (DN) loads, known precursors of the hypoxia in the Bay. We used the process model LM3-TAN (Terrestrial and Aquatic Nitrogen), which is capable of capturing both seasonal and decadal-to-century changes in vegetation-soil-river N storage, and produced nine scenarios of DN-load distributions under different short-term scenarios of climate variability and extremes. We illustrate that after 1 to 3 yearlong dry spells, the likelihood of exceeding a threshold DN load (56 kt yr-1) increases by 40 to 65% due to flushing of N accumulated throughout the dry spells and altered microbial processes. Our analyses suggest that possible future increases in climate variability/extremes—specifically, high precipitation occurring after multiyear dry spells—could likely lead to high DN-load anomalies and hypoxia.

  14. Soil carbon accumulation after short-term use of rye as a winter cover crop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of winter cover crops has been proposed to protect and enhance soil resources. Cereal rye (Secale cereale L.) can be an effective cover crop since it can produce large amounts of biomass in certain climates. However, short-term benefits of cover crop use on soil carbon accumulation are not w...

  15. Food Price Volatility and Decadal Climate Variability

    NASA Astrophysics Data System (ADS)

    Brown, M. E.

    2013-12-01

    The agriculture system is under pressure to increase production every year as global population expands and more people move from a diet mostly made up of grains, to one with more meat, dairy and processed foods. Weather shocks and large changes in international commodity prices in the last decade have increased pressure on local food prices. This paper will review several studies that link climate variability as measured with satellite remote sensing to food price dynamics in 36 developing countries where local monthly food price data is available. The focus of the research is to understand how weather and climate, as measured by variations in the growing season using satellite remote sensing, has affected agricultural production, food prices and access to food in agricultural societies. Economies are vulnerable to extreme weather at multiple levels. Subsistence small holders who hold livestock and consume much of the food they produce are vulnerable to food production variability. The broader society, however, is also vulnerable to extreme weather because of the secondary effects on market functioning, resource availability, and large-scale impacts on employment in trading, trucking and wage labor that are caused by weather-related shocks. Food price variability captures many of these broad impacts and can be used to diagnose weather-related vulnerability across multiple sectors. The paper will trace these connections using market-level data and analysis. The context of the analysis is the humanitarian aid community, using the guidance of the USAID Famine Early Warning Systems Network and the United Nation's World Food Program in their response to food security crises. These organizations have worked over the past three decades to provide baseline information on food production through satellite remote sensing data and agricultural yield models, as well as assessments of food access through a food price database. Econometric models and spatial analysis are used

  16. Short-term predictions in forex trading

    NASA Astrophysics Data System (ADS)

    Muriel, A.

    2004-12-01

    Using a kinetic equation that is used to model turbulence (Physica A, 1985-1988, Physica D, 2001-2003), we redefine variables to model the time evolution of the foreign exchange rates of three major currencies. We display live and predicted data for one period of trading in October, 2003.

  17. Impact of climate variability on tropospheric ozone.

    PubMed

    Grewe, Volker

    2007-03-01

    A simulation with the climate-chemistry model (CCM) E39/C is presented, which covers both the troposphere and stratosphere dynamics and chemistry during the period 1960 to 1999. Although the CCM, by its nature, is not exactly representing observed day-by-day meteorology, there is an overall model's tendency to correctly reproduce the variability pattern due to an inclusion of realistic external forcings, like observed sea surface temperatures (e.g. El Niño), major volcanic eruption, solar cycle, concentrations of greenhouse gases, and Quasi-Biennial Oscillation. Additionally, climate-chemistry interactions are included, like the impact of ozone, methane, and other species on radiation and dynamics, and the impact of dynamics on emissions (lightning). However, a number of important feedbacks are not yet included (e.g. feedbacks related to biogenic emissions and emissions due to biomass burning). The results show a good representation of the evolution of the stratospheric ozone layer, including the ozone hole, which plays an important role for the simulation of natural variability of tropospheric ozone. Anthropogenic NO(x) emissions are included with a step-wise linear trend for each sector, but no interannual variability is included. The application of a number of diagnostics (e.g. marked ozone tracers) allows the separation of the impact of various processes/emissions on tropospheric ozone and shows that the simulated Northern Hemisphere tropospheric ozone budget is not only dominated by nitrogen oxide emissions and other ozone pre-cursors, but also by changes of the stratospheric ozone budget and its flux into the troposphere, which tends to reduce the simulated positive trend in tropospheric ozone due to emissions from industry and traffic during the late 80s and early 90s. For tropical regions the variability in ozone is dominated by variability in lightning (related to ENSO) and stratosphere-troposphere exchange (related to Northern Hemisphere Stratospheric

  18. Principal nonlinear dynamical modes of climate variability

    NASA Astrophysics Data System (ADS)

    Mukhin, Dmitry; Gavrilov, Andrey; Feigin, Alexander; Loskutov, Evgeny; Kurths, Juergen

    2015-10-01

    We suggest a new nonlinear expansion of space-distributed observational time series. The expansion allows constructing principal nonlinear manifolds holding essential part of observed variability. It yields low-dimensional hidden time series interpreted as internal modes driving observed multivariate dynamics as well as their mapping to a geographic grid. Bayesian optimality is used for selecting relevant structure of nonlinear transformation, including both the number of principal modes and degree of nonlinearity. Furthermore, the optimal characteristic time scale of the reconstructed modes is also found. The technique is applied to monthly sea surface temperature (SST) time series having a duration of 33 years and covering the globe. Three dominant nonlinear modes were extracted from the time series: the first efficiently separates the annual cycle, the second is responsible for ENSO variability, and combinations of the second and the third modes explain substantial parts of Pacific and Atlantic dynamics. A relation of the obtained modes to decadal natural climate variability including current hiatus in global warming is exhibited and discussed.

  19. Impact of large-scale climate variability and change on crop yields in Africa: An observational assessment

    NASA Astrophysics Data System (ADS)

    Smoliak, B. V.; Po-Chedley, S.; Cullen, A. C.

    2011-12-01

    Assessments of the relationships between climate and agricultural production have progressed from opposite ends of the spatio-temporal spectrum. While studies of global-scale climate-yield relationships have provided estimates of the impact of multi-decadal trends in temperature and precipitation on recent production, studies of local weather impacts on yield have demonstrated the influence of temperature and precipitation variability on plant physiology, particularly with respect to the duration and timing of extremes. At intermediate spatial and temporal scales, somewhat of a gap in understanding exists. Our investigation contributes to better understanding climate-yield relationships at intermediate scales by assessing the impact of climate variability on crop yields at the country to continent scale on interannual to interdecadal timescales. Toward this end, we employ historical climatic data and reported cereal crop yields from the African continent, 1961 to 2009, in conjunction with principal component regression and partial least squares regression. Our results show that a discrete set of spatial patterns of climate variability account for up to half of the year-to-year variability in crop yields over portions of Africa. The impact of this climate variability is particularly strong in Sub-Saharan Africa, where large or prolonged deficits in yields can result in food shortages. The fundamental patterns of variability used to explain yield fluctuations are based on temperature and precipitation, chosen due to their influence on plant physiology; however, the time-varying behavior of the patterns may also be linked to coherent large-scale climate variability through regressions with sea surface temperature, sea level pressure and low-level wind fields. Results are distilled in terms of five UN designated geographic regions of Africa. Implications for short-term food security and future climate change are discussed.

  20. Environmental forcing and Southern Ocean marine predator populations: effects of climate change and variability.

    PubMed

    Trathan, P N; Forcada, J; Murphy, E J

    2007-12-29

    The Southern Ocean is a major component within the global ocean and climate system and potentially the location where the most rapid climate change is most likely to happen, particularly in the high-latitude polar regions. In these regions, even small temperature changes can potentially lead to major environmental perturbations. Climate change is likely to be regional and may be expressed in various ways, including alterations to climate and weather patterns across a variety of time-scales that include changes to the long interdecadal background signals such as the development of the El Niño-Southern Oscillation (ENSO). Oscillating climate signals such as ENSO potentially provide a unique opportunity to explore how biological communities respond to change. This approach is based on the premise that biological responses to shorter-term sub-decadal climate variability signals are potentially the best predictor of biological responses over longer time-scales. Around the Southern Ocean, marine predator populations show periodicity in breeding performance and productivity, with relationships with the environment driven by physical forcing from the ENSO region in the Pacific. Wherever examined, these relationships are congruent with mid-trophic-level processes that are also correlated with environmental variability. The short-term changes to ecosystem structure and function observed during ENSO events herald potential long-term changes that may ensue following regional climate change. For example, in the South Atlantic, failure of Antarctic krill recruitment will inevitably foreshadow recruitment failures in a range of higher trophic-level marine predators. Where predator species are not able to accommodate by switching to other prey species, population-level changes will follow. The Southern Ocean, though oceanographically interconnected, is not a single ecosystem and different areas are dominated by different food webs. Where species occupy different positions in

  1. Short-Term Training--Where the Action Is!

    ERIC Educational Resources Information Center

    Moore, George R.

    In order to address major permanent changes in the economic structure and workforce of its community, Chemeketa Community College (CCC) in Oregon has made a commitment to initiate as many short-term training programs as its resources permit. Short-term training, which takes less time than regular one-year certificate or two-year associate degree…

  2. Double Dissociations in Visual and Spatial Short-Term Memory

    ERIC Educational Resources Information Center

    Klauer, Karl Christoph; Zhao, Zengmei

    2004-01-01

    A visual short-term memory task was more strongly disrupted by visual than spatial interference, and a spatial memory task was simultaneously more strongly disrupted by spatial than visual interference. This double dissociation supports a fractionation of visuospatial short-term memory into separate visual and spatial components. In 6 experiments,…

  3. 22 CFR 62.21 - Short-term scholars.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Short-term scholars. 62.21 Section 62.21 Foreign Relations DEPARTMENT OF STATE PUBLIC DIPLOMACY AND EXCHANGES EXCHANGE VISITOR PROGRAM Specific Program Provisions § 62.21 Short-term scholars. (a) Introduction. These regulations govern scholars coming to the United States for a period of up...

  4. 75 FR 19285 - Short-Term Lending Program (STLP)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-14

    ...This final rule governs the Short Term Lending Program (STLP), which provides financial assistance in the form of guarantees of short- term revolving lines of credit from Participating Lenders (PLs) to disadvantaged Business Enterprises (DBEs) and other certified small and disadvantaged business (SDBs) in connection with transportation-related contracts at the local, state and federal levels.......

  5. Short-term energy outlook annual supplement, 1993

    SciTech Connect

    1993-08-06

    The Short-Term Energy Outlook Annual Supplement (supplement) is published once a year as a complement to the Short-Term Energy Outlook (Outlook), Quarterly Projections. The purpose of the Supplement is to review the accuracy of the forecasts published in the Outlook, make comparisons with other independent energy forecasts, and examine current energy topics that affect the forecasts.

  6. Short-Term Group Treatment for Adult Children of Alcoholics.

    ERIC Educational Resources Information Center

    Cooper, Alvin; McCormack, WIlliam A.

    1992-01-01

    Adult children of alcoholics (n=24) were tested on measures of loneliness, anxiety, hostility, depression, and interpersonal dependency before and after participation in short-term group therapy. Highly significant test score changes supported effectiveness of individual therapy in short-term groups. (Author/NB)

  7. 22 CFR 62.21 - Short-term scholars.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Short-term scholars. 62.21 Section 62.21 Foreign Relations DEPARTMENT OF STATE PUBLIC DIPLOMACY AND EXCHANGES EXCHANGE VISITOR PROGRAM Specific Program Provisions § 62.21 Short-term scholars. (a) Introduction. These regulations govern scholars...

  8. Using Remote Sensing to Understand Climate Variability

    NASA Astrophysics Data System (ADS)

    Green, J.; Gentine, P.

    2014-12-01

    While a major source of uncertainty in global climate model predictions is due to the coarseness of their resolution, a significant amount of error is also generated due to the lack of information regarding the interactions between atmospheric and land parameters over time. When the behavior of a certain parameter is not clearly understood it is frequently estimated as one specific value while in reality it may vary with time and space. Remote sensing is allowing researchers to better estimate each of these parameters so one can see how they change with time. This study is an effort to improve our knowledge of the inter-annual and seasonal variability in radiation, water and the carbon cycle using remote sensing products on a global scale. By examining monthly data over a multi-year period (data parameter and source are listed in Table 1) for fluorescence, groundwater, net radiation, vegetation indices, precipitation, soil moisture and evapotranspiration, we should be able to determine the behavior and interactions between these parameters and better understand how they vary together seasonally, annually and year to year. With this information it is our hope that global climate models can be improved to better understand what is occurring climatologically in the present as well as more accurately make predictions about future conditions. Table 1. Parameters and Sources Parameter Source Fluorescence Greenhouse gases Observing SATellite (GOSAT)1 Groundwater Gravity Recovery and Climate Experiment (GRACE) Net Radiation Clouds and the Earth's Radiant Energy System (CERES) Vegetation Indices Moderate Resolution Imaging Spectroradiometer (MODIS)/ Multiangle Implementation of Atmospheric Correction (MAIAC) Precipitation Global Precipitation Climatology Project (GPCP) Soil Moisture Water Cycle Mutimission Observation Strategy (WACMOS) Evapotranspiration Global Land-surface Evaporation: the Amsterdam Methodology (GLEAM) 1In future work, we hope to use fluorescence data from

  9. Tufted puffin reproduction reveals ocean climate variability.

    PubMed

    Gjerdrum, Carina; Vallée, Anne M J; St Clair, Colleen Cassady; Bertram, Douglas F; Ryder, John L; Blackburn, Gwylim S

    2003-08-01

    Anomalously warm sea-surface temperatures (SSTs) are associated with interannual and decadal variability as well as with long-term climate changes indicative of global warming. Such oscillations could precipitate changes in a variety of oceanic processes to affect marine species worldwide. As global temperatures continue to rise, it will be critically important to be able to predict the effects of such changes on species' abundance, distribution, and ecological relationships so as to identify vulnerable populations. Off the coast of British Columbia, warm SSTs have persisted through the last two decades. Based on 16 years of reproductive data collected between 1975 and 2002, we show that the extreme variation in reproductive performance exhibited by tufted puffins (Fratercula cirrhata) was related to changes in SST both within and among seasons. Especially warm SSTs corresponded with drastically decreased growth rates and fledging success of puffin nestlings. Puffins may partially compensate for within-season changes associated with SST by adjusting their breeding phenology, yet our data also suggest that they are highly vulnerable to the effects of climate change at this site and may serve as a valuable indicator of biological change in the North Pacific. Further and prolonged increases in ocean temperature could make Triangle Island, which contains the largest tufted puffin colony in Canada, unsuitable as a breeding site for this species. PMID:12871995

  10. Climatic variability, plant phenology, and northern ungulates

    SciTech Connect

    Post, E.; Stenseth, N.C.

    1999-06-01

    Models of climate change predict that global temperatures and precipitation will increase within the next century, with the most pronounced changes occurring in northern latitudes and during winter. A large-scale atmospheric phenomenon, the North Atlantic Oscillation (NAO), is a strong determinant of both interannual variation and decadal trends in temperatures and precipitation during winter in northern latitudes, and its recent persistence in one extreme phase may be a substantial component of increases in global temperatures. Hence, the authors investigated the influences of large-scale climatic variability on plant phenology and ungulate population ecology by incorporating the NAO in statistical analyses of previously published data on: (1) the timing of flowering by plants in Norway, and (2) phenotypic and demographic variation in populations of northern ungulates. The authors analyzed 137 time series on plant phenology for 13 species of plants in Norway spanning up to 50 yr and 39 time series on phenotypic and demographic traits of 7 species of northern ungulates from 16 populations in North America and northern Europe spanning up to 30 yr.

  11. Cyclical konzo epidemics and climate variability.

    PubMed

    Oluwole, Olusegun Steven A

    2015-03-01

    Konzo epidemics have occurred during droughts in the Democratic Republic of Congo (DR Congo) for >70 years, but also in Mozambique, Tanzania, and the Central African Republic. The illness is attributed to exposure to cyanide from cassava foods, on which the population depends almost exclusively during droughts. Production of cassava, a drought-resistant crop, has been shown to correlate with cyclical changes in precipitation in konzo-affected countries. Here we review the epidemiology of konzo as well as models of its pathogenesis. A spectral analysis of precipitation and konzo is performed to determine whether konzo epidemics are cyclical and whether there is spectral coherence. Time series of environmental temperature, precipitation, and konzo show cyclical changes. Periodicities of dominant frequencies in the spectra of precipitation and konzo range from 3 to 6 years in DR Congo. There is coherence of the spectra of precipitation and konzo. The magnitude squared coherence of 0.9 indicates a strong relationship between variability of climate and konzo epidemics. Thus, it appears that low precipitation phases of climate variability reduce the yield of food crops except cassava, upon which the population depends for supply of calories during droughts. Presence of very high concentrations of thiocyanate (SCN(-) ), the major metabolite of cyanide, in the bodily fluids of konzo subjects is a consequence of dietary exposure to cyanide, which follows intake of poorly processed cassava roots. Because cyanogens and minor metabolites of cyanide have not induced konzo-like illnesses, SCN(-) remains the most likely neurotoxicant of konzo. Public health control of konzo will require food and water programs during droughts. [Correction added on 26 February 2015, after first online publication: abstract reformatted per journal style] PMID:25523348

  12. Safety nets can help address the risks to nutrition from increasing climate variability.

    PubMed

    Alderman, Harold

    2010-01-01

    Models of climate change predict increased variability of weather as well as changes in agro-ecology. The increased variability will pose special challenges for nutrition. This study reviews evidence on climate shocks and nutrition and estimates the economic consequences in terms of reduced schooling and economic productivity stemming from nutritional insults in childhood. Panel data covering up to 20 y indicate that that short-term climate shocks have long-term impacts on children that persist, often into their adult lives. Other studies document the potential for relief programs to offset these shocks providing that the programs can be implemented with flexible financing, rapid identification of those affected by the shock, and timely scale-up. The last of these presumes that programs are already in place with contingency plans drawn up. Arguably, direct food distribution, including that of ready-to-use therapeutic food, may be part of the overall strategy. Even if such programs are too expensive for sustainable widespread use in the prevention of malnutrition, scalable food distribution programs may be cost effective to address the heightened risk of malnutrition following weather-related shocks. PMID:19923387

  13. An 8700 Year Record of Holocene Climate Variability from the Yucatan Peninsula

    NASA Astrophysics Data System (ADS)

    Wahl, D.; Byrne, R.; Anderson, L.

    2013-12-01

    Our understanding of Holocene climate change in the Maya lowlands of Central America has improved significantly during the last several decades thanks to the development of proxy climate records from lake cores and speleothems. One important finding is that longer-term climate changes (i.e., millennial scale) were driven primarily by precessional forcing; less clear, however, are the causes of abrupt shifts and higher frequency (centennial to decadal) change recognized in many Holocene climate reconstructions. The mechanisms driving climate change on these time scales have been difficult to identify in the region, in part because the Yucatan peninsula is influenced by climatic conditions linked to both the tropical Atlantic and Pacific oceans. Additional complications arise from the development of dense human populations following the initial introduction of agriculture ~5000 cal yr BP, which had significant impact on the environment as a whole. Here we present the results of analyses (stable isotope, pollen, magnetic susceptibility, and physical properties) of a 7.25 m sediment core from Lago Puerto Arturo, a closed basin lake in the northern Peten, Guatemala. An age-depth model, based on 6 AMS radiocarbon determinations and created using CLAM, indicates the record extends to 8700 cal yr BP. Proxy data suggest that, similar to other low latitude sites, millennial scale climate at Lago Puerto Arturo was driven by changes in insolation. Higher frequency variability is associated with El Niño/Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO) dynamics, reflecting latitudinal shifts in the Intertropical Convergence Zone in both the tropical North Atlantic and North Pacific. Solar forcing may also play a role in short-term climate change. The pollen and isotope records show that the entire period of prehispanic settlement and agricultural activity, i.e. ~5000-1000 cal yr B.P., was characterized by relatively dry conditions compared to before or after.

  14. Climate Variability and the Settlement of Oceania

    NASA Astrophysics Data System (ADS)

    Avis, C.; Montenegro, A.; Weaver, A. J.

    2007-12-01

    The initial discovery and settlement of the islands of Oceania is an important issue in Pacific anthropology. Settlement of this region generally proceeded against the direction of the dominant trade winds leading to questions concerning the degree of maritime skill possessed by early Pacific mariners. We use a computer simulation to test two basic exploration strategies: drift voyages and downwind sailing, focusing on the region of the initial eastward expansion into Oceania by the Lapita people. Simulations are driven by high resolution surface wind and current data from atmosphere and ocean models forced by real observations and which capture the high degree of seasonal and interannual variability in the region. We find that climatic variability associated with the Australian monsoon circulation and El Nino plays a key role in facilitating eastward crossings. Both drift and sailing voyages can account for the discovery of all the islands in the Lapita region based on initial starting points in the Bismarck and Solomon archipelagos. Many of our findings differ from an important, earlier modeling study performed by Levison et al. (1973).

  15. Short term memory for tactile stimuli.

    PubMed

    Gallace, Alberto; Tan, Hong Z; Haggard, Patrick; Spence, Charles

    2008-01-23

    Research has shown that unreported information stored in rapidly decaying visual representations may be accessed more accurately using partial report than using full report procedures (e.g., [Sperling, G., 1960. The information available in brief visual presentations. Psychological Monographs, 74, 1-29.]). In the 3 experiments reported here, we investigated whether unreported information regarding the actual number of tactile stimuli presented in parallel across the body surface can be accessed using a partial report procedure. In Experiment 1, participants had to report the total number of stimuli in a tactile display composed of up to 6 stimuli presented across their body (numerosity task), or else to detect whether or not a tactile stimulus had previously been presented in a position indicated by a visual probe given at a variable delay after offset of a tactile display (i.e., partial report). The results showed that participants correctly reported up to 3 stimuli in the numerosity judgment task, but their performance was significantly better than chance when up to 5 stimuli were presented in the partial report task. This result shows that short-lasting tactile representations can be accessed using partial report procedures similar to those used previously in visual studies. Experiment 2 showed that the duration of these representations (or the time available to consciously access them) depends on the number of stimuli presented in the display (the greater the number of stimuli that are presented, the faster their representation decays). Finally, the results of a third experiment showed that the differences in performance between the numerosity judgment and partial report tasks could not be explained solely in terms of any difference in task difficulty. PMID:18083147

  16. Effects of climate variability and extreme events on components of the carbon balance in Europe during 1961-2100

    NASA Astrophysics Data System (ADS)

    Beer, Christian; Carvalhais, Nuno; Ciais, Philippe; Balkovic, Juraj; Davin, Edouard; Kato, Tomomichi; Kuhnert, Matthias; Lardy, Romain; Laperche, Sylvain; Martin, Raphaël; van Oijen, Marcel; Rammig, Anja; Rolinski, Susanne; Seneviratne, Sonia; Smith, Pete; Thonicke, Kirsten; van der Velde, Marijn; Vieli, Barla; Viovy, Nicolas; Reichstein, Markus

    2013-04-01

    Regional climate models project a change in the annual and seasonal mean of meteorological variables in Europe until the end of the century, e. g. mean air temperature is predicted to dramatically increase until 2100. At the same time, the shape of the probability distribution of meteorological variables will change, leading to an altered variability of meteorological variables and frequency of extreme events. Today, the isolated effects of changing variance versus changing mean of meteorological drivers on ecosystem processes, such as gross primary production, autotrophic and heterotrophic respiration, evapotranspiration, mortality and disturbances have not been quantified at a continental or global scale. We contribute to such quantification from a theoretical, mechanistic modelling point of view by artificial modelling experiments using state-of-the-art generic (LPJmL, ORCHIDEE, JSBACH, CLM) and sectorial (BASFOR, DailyDayCent, PASIM) ecosystem models that has been performed in the EU FP7 project CARBO-Extreme. Using a control climate data set (CNTL) based on the WATCH forcing data and bias-corrected ECMWF ERA-Interim reanalysis data, factorial model experiments with transient/constant climate and atmospheric [CO2] concentration have been performed.Then, these factorial experiments were repeated using a climate dataset in which climate variables hold the same long-term seasonal and annual mean but show much reduced short-term variability ("reduced variability"). Analysis of the resulting carbon and water balance estimations for Europe during 1961-2100 enabled disentangling direct effects of temperature or radiation variability from effects of general climate variability and effects of a trend in mean climate conditions on ecosystem functions. Generally, reduced variability in short-wave radiation increased the annual gross primary production due to the concave shape of the light response curve of photosynthesis. Therefore, net primary production is also

  17. An integrated dynamic modeling framework for investigating the impact of climate change and variability on irrigated agriculture

    NASA Astrophysics Data System (ADS)

    Rowan, Timothy S. C.; Maier, Holger R.; Connor, Jeff; Dandy, Graeme C.

    2011-07-01

    Many hydrologic systems are likely to be affected by climate change. This is of particular importance given that agricultural production systems are inextricably linked to the hydrologic systems they rely upon. Although irrigation is often employed as a method to dampen the effect of short-term variation in climatic inputs to agricultural production, sources of irrigation water are not immune to long-term climatic change. Irrigation water use decisions are most often made at the farm level. It is at this scale that the economic and social impacts of climate change will be manifest. This paper presents an integrated stochastic dynamic modeling framework that can be used to investigate the viability of irrigated farms under alternative climate change scenarios. The framework is applied to a theoretical farm in the Murray Darling Basin, Australia, under four potential future climate scenarios. It is found that neglecting interannual variability in climatic inputs to agriculture consistently underestimates the reduction in farm viability caused by climate change and that multiyear sequences of climate states strongly influence estimates of farm profitability.

  18. How does spatial variability of climate affect catchment streamflow predictions?

    EPA Science Inventory

    Spatial variability of climate can negatively affect catchment streamflow predictions if it is not explicitly accounted for in hydrologic models. In this paper, we examine the changes in streamflow predictability when a hydrologic model is run with spatially variable (distribute...

  19. Short-Term Teacher Workshops: Examining the Assumption of Teacher-to-Student Transfer.

    ERIC Educational Resources Information Center

    Storti, Janet

    This study explored the feasibility of evaluating the effectiveness of learning transfer from National Aeronautics and Space Administration (NASA) short-term (1 day or less) workshops to the teacher and through the teacher to the student, focusing on attitude toward science, science-related behavior, and knowledge variables. Participants were 33…

  20. Roles for short-term synaptic plasticity in behavior.

    PubMed

    Fortune, Eric S; Rose, Gary J

    2002-01-01

    Short-term synaptic plasticity is phylogenetically widespread in ascending sensory systems of vertebrate brains. Such plasticity is found at all levels of sensory processing, including in sensory cortices. The functional roles of this apparently ubiquitous short-term synaptic plasticity, however, are not well understood. Data obtained in midbrain electrosensory neurons of Eigenmannia suggest that this plasticity has at least two roles in sensory processing; enhancing low-pass temporal filtering and generating phase shifts used in processing moving sensory images. Short-term synaptic plasticity may serve similar roles in other sensory modalities, including vision. PMID:14692501

  1. Short-term energy outlook. Quarterly projections, Third quarter 1995

    SciTech Connect

    1995-08-02

    The Energy Information Administration (EIA) prepares quarterly, short-term energy supply, demand, and price projections for publication in February, May, August, and November in the Short-Term Energy Outlook (Outlook). An annual supplement analyzes the performance of previous forecasts, compares recent projections with those of other forecasting services, and discusses current topics related to the short-term energy markets. The forecast period for this issue of the Outlook extends from the third quarter of 1995 through the fourth quarter of 1996. Values for the second quarter of 1995, however, are preliminary EIA estimates.

  2. Auditory Short-Term Memory Behaves Like Visual Short-Term Memory

    PubMed Central

    Visscher, Kristina M; Kaplan, Elina; Kahana, Michael J; Sekuler, Robert

    2007-01-01

    Are the information processing steps that support short-term sensory memory common to all the senses? Systematic, psychophysical comparison requires identical experimental paradigms and comparable stimuli, which can be challenging to obtain across modalities. Participants performed a recognition memory task with auditory and visual stimuli that were comparable in complexity and in their neural representations at early stages of cortical processing. The visual stimuli were static and moving Gaussian-windowed, oriented, sinusoidal gratings (Gabor patches); the auditory stimuli were broadband sounds whose frequency content varied sinusoidally over time (moving ripples). Parallel effects on recognition memory were seen for number of items to be remembered, retention interval, and serial position. Further, regardless of modality, predicting an item's recognizability requires taking account of (1) the probe's similarity to the remembered list items (summed similarity), and (2) the similarity between the items in memory (inter-item homogeneity). A model incorporating both these factors gives a good fit to recognition memory data for auditory as well as visual stimuli. In addition, we present the first demonstration of the orthogonality of summed similarity and inter-item homogeneity effects. These data imply that auditory and visual representations undergo very similar transformations while they are encoded and retrieved from memory. PMID:17311472

  3. Short-term load forecasting using neural network for future smart grid application

    NASA Astrophysics Data System (ADS)

    Zennamo, Joseph Anthony, III

    Short-term load forecasting of power system has been a classic problem for a long time. Not merely it has been researched extensively and intensively, but also a variety of forecasting methods has been raised. This thesis outlines some aspects and functions of smart meter. It also presents different policies and current statuses as well as future projects and objectives of SG development in several countries. Then the thesis compares main aspects about latest products of smart meter from different companies. Lastly, three types of prediction models are established in MATLAB to emulate the functions of smart grid in the short-term load forecasting, and then their results are compared and analyzed in terms of accuracy. For this thesis, more variables such as dew point temperature are used in the Neural Network model to achieve more accuracy for better short-term load forecasting results.

  4. Short-term landfill methane emissions dependency on wind.

    PubMed

    Delkash, Madjid; Zhou, Bowen; Han, Byunghyun; Chow, Fotini K; Rella, Chris W; Imhoff, Paul T

    2016-09-01

    Short-term (2-10h) variations of whole-landfill methane emissions have been observed in recent field studies using the tracer dilution method for emissions measurement. To investigate the cause of these variations, the tracer dilution method is applied using 1-min emissions measurements at Sandtown Landfill (Delaware, USA) for a 2-h measurement period. An atmospheric dispersion model is developed for this field test site, which is the first application of such modeling to evaluate atmospheric effects on gas plume transport from landfills. The model is used to examine three possible causes of observed temporal emissions variability: temporal variability of surface wind speed affecting whole landfill emissions, spatial variability of emissions due to local wind speed variations, and misaligned tracer gas release and methane emissions locations. At this site, atmospheric modeling indicates that variation in tracer dilution method emissions measurements may be caused by whole-landfill emissions variation with wind speed. Field data collected over the time period of the atmospheric model simulations corroborate this result: methane emissions are correlated with wind speed on the landfill surface with R(2)=0.51 for data 2.5m above ground, or R(2)=0.55 using data 85m above ground, with emissions increasing by up to a factor of 2 for an approximately 30% increase in wind speed. Although the atmospheric modeling and field test are conducted at a single landfill, the results suggest that wind-induced emissions may affect tracer dilution method emissions measurements at other landfills. PMID:26896003

  5. Short term fluctuations of wind and solar power systems

    NASA Astrophysics Data System (ADS)

    Anvari, M.; Lohmann, G.; Wächter, M.; Milan, P.; Lorenz, E.; Heinemann, D.; Rahimi Tabar, M. Reza; Peinke, Joachim

    2016-06-01

    Wind and solar power are known to be highly influenced by weather events and may ramp up or down abruptly. Such events in the power production influence not only the availability of energy, but also the stability of the entire power grid. By analysing significant amounts of data from several regions around the world with resolutions of seconds to minutes, we provide strong evidence that renewable wind and solar sources exhibit multiple types of variability and nonlinearity in the time scale of seconds and characterise their stochastic properties. In contrast to previous findings, we show that only the jumpy characteristic of renewable sources decreases when increasing the spatial size over which the renewable energies are harvested. Otherwise, the strong non-Gaussian, intermittent behaviour in the cumulative power of the total field survives even for a country-wide distribution of the systems. The strong fluctuating behaviour of renewable wind and solar sources can be well characterised by Kolmogorov-like power spectra and q-exponential probability density functions. Using the estimated potential shape of power time series, we quantify the jumpy or diffusive dynamic of the power. Finally we propose a time delayed feedback technique as a control algorithm to suppress the observed short term non-Gaussian statistics in spatially strong correlated and intermittent renewable sources.

  6. Short-term energy outlook, quarterly projections, first quarter 1998

    SciTech Connect

    1998-01-01

    The forecast period for this issue of the Outlook extends from the first quarter of 1998 through the fourth quarter of 1999. Values for the fourth quarter of 1997, however, are preliminary EIA estimates (for example, some monthly values for petroleum supply and disposition are derived in part from weekly data reported in EIA`s Weekly Petroleum Status Report) or are calculated from model simulations that use the latest exogenous information available (for example, electricity sales and generation are simulated by using actual weather data). The historical energy data, compiled in the first quarter 1998 version of the Short-Term Integrated Forecasting System (STIFS) database, are mostly EIA data regularly published in the Monthly Energy Review, Petroleum Supply Monthly, and other EIA publications. Minor discrepancies between the data in these publications and the historical data in this Outlook are due to independent rounding. The STIFS model is driven principally by three sets of assumptions or inputs: estimates of key macroeconomic variables, world oil price assumptions, and assumptions about the severity of weather. Macroeconomic estimates are adjusted by EIA to reflect EIA assumptions which may affect the macroeconomic outlook. By varying the assumptions, alternative cases are produced by using the STIFS model. 24 figs., 19 tabs.

  7. Leukocyte subsets and neutrophil function after short-term spaceflight

    NASA Technical Reports Server (NTRS)

    Stowe, R. P.; Sams, C. F.; Mehta, S. K.; Kaur, I.; Jones, M. L.; Feeback, D. L.; Pierson, D. L.

    1999-01-01

    Changes in leukocyte subpopulations and function after spaceflight have been observed but the mechanisms underlying these changes are not well defined. This study investigated the effects of short-term spaceflight (8-15 days) on circulating leukocyte subsets, stress hormones, immunoglobulin levels, and neutrophil function. At landing, a 1.5-fold increase in neutrophils was observed compared with preflight values; lymphocytes were slightly decreased, whereas the results were variable for monocytes. No significant changes were observed in plasma levels of immunoglobulins, cortisol, or adrenocorticotropic hormone. In contrast, urinary epinephrine, norepinephrine, and cortisol were significantly elevated at landing. Band neutrophils were observed in 9 of 16 astronauts. Neutrophil chemotactic assays showed a 10-fold decrease in the optimal dose response after landing. Neutrophil adhesion to endothelial cells was increased both before and after spaceflight. At landing, the expression of MAC-1 was significantly decreased while L-selectin was significantly increased. These functional alterations may be of clinical significance on long-duration space missions.

  8. Synchronous dynamics in the presence of short-term plasticity

    NASA Astrophysics Data System (ADS)

    di Volo, Matteo; Livi, Roberto; Luccioli, Stefano; Politi, Antonio; Torcini, Alessandro

    2013-03-01

    We investigate the occurrence of quasisynchronous events in a random network of excitatory leaky integrate-and-fire neurons equipped with short-term plasticity. The dynamics is analyzed by monitoring both the evolution of global synaptic variables and, on a microscopic ground, the interspike intervals of the individual neurons. We find that quasisynchronous events are the result of a mixture of synchronized and unsynchronized motion, analogously to the emergence of synchronization in the Kuramoto model. In the present context, disorder is due to the random structure of the network and thereby vanishes for a diverging network size N (i.e., in the thermodynamic limit), when statistical fluctuations become negligible. Remarkably, the fraction of asynchronous neurons remains strictly larger than zero for arbitrarily large N. This is due to the presence of a robust homoclinic cycle in the self-generated synchronous dynamics. The nontrivial large-N behavior is confirmed by the anomalous scaling of the maximum Lyapunov exponent, which is strictly positive in a finite network and decreases as N-0.27. Finally, we have checked the robustness of this dynamical phase with respect to the addition of noise, applied to either the reset potential or the leaky current.

  9. Short-term Dynamic Psychotherapy versus Sertraline in Treatment of Social Phobia

    PubMed Central

    Nader-Mohammadi Moghadam, Mehryar; Atef-Vahid, Mohammad-Kazem; Asgharnejad-Farid, Ali-Asghar; Shabani, Amir; Lavasni, Fahimeh

    2015-01-01

    Background: A few studies on short-term psychodynamic approach have been conducted on social phobia. Objectives: In this study, the effectiveness of short-term psychodynamic psychotherapy on the treatment of social phobia has been compared to the effectiveness of sertraline and waiting list. Materials and Methods: In this randomized-controlled trial study, 13 male students were treated with short-term dynamic psychotherapy (McCullough method) lasting 25 sessions, 11 students received sertraline for 12 weeks, and 14 students, as the waiting list, received no intervention for 8 weeks. Participants completed the Social Phobia Inventory (SPIN) as primary efficacy variable 4 times, and were rated with Clinical Global Impression scale (CGI) and Global Assessment of Functioning (GAF) as secondary efficacy variables. The data were analyzed with analysis of variance (ANOVA), analysis of covariance (ANCOVA), general linear model repeated measures analysis of variance and Fisher exact test. Results: ANCOVA showed significant differences between groups based on SPIN scores (F = 23.51, Sig. = 0.001) and Bonferroni test, as post hoc compression, showed means of both short-term dynamic therapy and sertraline therapy groups were significantly different from waiting list mean (STDP-WL: x̅dif = 15.76, Sig. = 0.001), (MED-WL: x̅ = 15.91, Sig. = 0.001). Mean of SPIN scores was not significantly different between short-term dynamic psychotherapy and pharmacotherapy groups. In both treatment groups, means of SPIN scores significantly decreased in posttest, but not in waiting. These results repeated with GAF and CGI scores. Conclusions: The results indicated that short-term dynamic psychotherapy sertraline are effective in decreasing social phobia symptoms and were superior to control group. PMID:26288643

  10. Short-Term Memory in Habituation and Dishabituation

    ERIC Educational Resources Information Center

    Whitlow, Jesse William, Jr.

    1975-01-01

    The present research evaluated the refractorylike response decrement, as found in habituation of auditory evoked peripheral vasoconstriction in rabbits, to determine whether or not it represents a short-term habituation process distinct from effector fatigue or sensory adaptation. (Editor)

  11. Regional Short-Term Energy Model (RSTEM) Overview

    EIA Publications

    2009-01-01

    The Regional Short-Term Energy Model (RSTEM) utilizes estimated econometric relationships for demand, inventories and prices to forecast energy market outcomes across key sectors and selected regions throughout the United States.

  12. UTILITY OF SHORT-TERM TESTS FOR GENETIC TOXICITY

    EPA Science Inventory

    By definition, short-term test (STTs) for genetic toxicity detect genotoxic agents, not carcinogens specifically. owever, there is ufficient evidence, based on mechanistic considerations alone, to say that genotoxic agents are potential carcinogens. TTs have high statistical powe...

  13. LAMPPOST: A Mnemonic Device for Teaching Climate Variables

    ERIC Educational Resources Information Center

    Fahrer, Chuck; Harris, Dan

    2004-01-01

    This article introduces the word "LAMPPOST" as a mnemonic device to aid in the instruction of climate variables. It provides instructors with a framework for discussing climate patterns that is based on eight variables: latitude, altitude, maritime influence and continentality, pressure systems, prevailing winds, ocean currents, storms, and…

  14. The paleoclimate record of long-term climate variability

    SciTech Connect

    Webb, R.S.; Bartlein, P.J.; Overpeck, J.T. Univ. of Oregon, Eugene )

    1993-06-01

    Climate variability occurs on time scales ranging from decades or shorter to millions of years. An important step in determining the effects of trace-gas-induced warming on climate variability and ecosystems is characterizing past natural variability and change. Throughout the Quaternary long-term climate variability has been dominated by Milankovitch forcing of glacial/interglacial cycles. Superimposed on this millennia-scale orbitally forced variability have been more rapid climate events (e.g. Younger Dryas, Little Ice Age, Medieval Warm Period, Sahelian droughts). Although highly relevant to understanding possible responses of ecosystems to future climate change, most decade to century scale climate variability remains poorly understood. Insights into mechanisms and responses can be obtained from tree rings, ice cores, corals, marine, lake and fluvial sediments, pollen, and macrofossils. These paleoclimate records reveal that the range of natural climate variability is much larger than indicated by the instrumental record of the past 150 years. Global networks of well-dated, high-resolution paleocrunate records for key intervals of the past are currently being assembled. These networks should provide the baseline of natural variability required to understand climate-ecosystem dynamics and to identify anthropogenic-induced change.

  15. Antarctic role in multi-centennial climate variability

    NASA Astrophysics Data System (ADS)

    Bakker, Pepijn; Clark, Peter U.; Golledge, Nicolas R.; Schmittner, Andreas

    2016-04-01

    Proxy-based reconstructions have revealed an important lack of multi-centennial climate variability in global climate models. Here we use a high-resolution ice-sheet model in combination with global climate simulations to show that internal variability in discharge of the West Antarctic Ice Sheet is a potentially important driver of multi-centennial climate variability. Variations in discharge impact the formation of Antarctic Bottom Water, that in turn impacts the climate at the earth's surface and in the deep ocean, in both near-field and far-field regions, through variations in the strength of the Atlantic meridional overturning circulation. If indeed interactions between the West Antarctic Ice Sheet and the climate on multi-centennial timescales are important, studying them in high resolution climate records has good potential to provide constraints on the dynamics of the West Antarctic Ice Sheet and its contribution to future sea-level rise.

  16. Encephalopathy and vestibulopathy following short-term hydrocarbon exposure

    SciTech Connect

    Hodgson, M.J.; Furman, J.; Ryan, C.; Durrant, J.; Kern, E.

    1989-01-01

    Dizziness, headaches, and weakness occurred among three men after short-term hydrocarbon exposure during improper welding procedures in a closed container. Symptoms were related to objective evidence of vestibular and cognitive dysfunction. Symptoms and abnormal test results persisted for 6 to 18 months. Simulation of the accident failed to demonstrate likely exposures except aliphatic hydrocarbons, well within the permissible exposure levels. Short-term exposures to neurotoxins may lead to long-term central nervous system abnormalities.

  17. Comparison of very short-term load forecasting techniques

    SciTech Connect

    Liu, K.; Kwan, C.; Lewis, F.L.; Subbarayan, S.; Shoults, R.R.; Manry, M.T.; Naccarino, J.

    1996-05-01

    Three practical techniques--Fuzzy Logic (FL), Neural Networks (NN), and Auto-regressive model (AR)--for very short-term load forecasting have been proposed and discussed in this paper. Their performances are evaluated through a simulation study. The preliminary study shows that it is feasible to design a simple, satisfactory dynamic forecaster to predict the very short-term load trends on-line. FL and NN can be good candidates for this application.

  18. Perceptions of short-term medical volunteer work: a qualitative study in Guatemala

    PubMed Central

    Green, Tyler; Green, Heidi; Scandlyn, Jean; Kestler, Andrew

    2009-01-01

    Background Each year medical providers from wealthy countries participate in short-term medical volunteer work in resource-poor countries. Various authors have raised concern that such work has the potential to be harmful to recipient communities; however, the social science and medical literature contains little research into the perceptions of short-term medical volunteer work from the perspective of members of recipient communities. This exploratory study examines the perception of short-term medical volunteer work in Guatemala among groups of actors affected by or participating in these programs. Methods The researchers conducted in-depth, semi-structured interviews with 72 individuals, including Guatemalan healthcare providers and health authorities, foreign medical providers, non-medical personnel working on health projects, and Guatemalan parents of children treated by a short-term volunteer group. Detailed notes and summaries of these interviews were uploaded, coded and annotated using Atlas.ti (Scientific Software Development GmbH, Berlin) to identify recurrent themes from the interviews. Results Informants commonly identified a need for increased access to medical services in Guatemala, and many believed that short-term medical volunteers are in a position to offer improved access to medical care in the communities where they serve. Informants most frequently cited appropriate patient selection and attention to payment systems as the best means to avoid creating dependence on foreign aid. The most frequent suggestion to improve short-term medical volunteer work was coordination with and respect for local Guatemalan healthcare providers and their communities, as insufficient understanding of the country's existing healthcare resources and needs may result in perceived harm to the recipient community. Conclusion The perceived impact of short-term medical volunteer projects in Guatemala is highly variable and dependent upon the individual project. In this

  19. Climate Variability and Change and Their Potential Health Effects in Small Island States: Information for Adaptation Planning in the Health Sector

    PubMed Central

    Ebi, Kristie L.; Lewis, Nancy D.; Corvalan, Carlos

    2006-01-01

    Small island states are likely the countries most vulnerable to climate variability and long-term climate change. Climate models suggest that small island states will experience warmer temperatures and changes in rainfall, soil moisture budgets, prevailing winds (speed and direction), and patterns of wave action. El Niño events likely will strengthen short-term and interannual climate variations. In addition, global mean sea level is projected to increase by 0.09–0.88 m by 2100, with variable effects on regional and local sea level. To better understand the potential human health consequences of these projected changes, a series of workshops and a conference organized by the World Health Organization, in partnership with the World Meteorological Organization and the United Nations Environment Programme, addressed the following issues: the current distribution and burden of climate-sensitive diseases in small island states, the potential future health impacts of climate variability and change, the interventions currently used to reduce the burden of climate-sensitive diseases, additional interventions that are needed to adapt to current and future health impacts, and the health implications of climate variability and change in other sectors. Information on these issues is synthesized and key recommendations are identified for improving the capacity of the health sector to anticipate and prepare for climate variability and change in small island states. PMID:17185291

  20. In Search of Decay in Verbal Short-Term Memory

    PubMed Central

    Berman, Marc G.; Jonides, John; Lewis, Richard L.

    2014-01-01

    Is forgetting in the short term due to decay with the mere passage of time, interference from other memoranda, or both? Past research on short-term memory has revealed some evidence for decay and a plethora of evidence showing that short-term memory is worsened by interference. However, none of these studies has directly contrasted decay and interference in short-term memory in a task that rules out the use of rehearsal processes. In this article the authors present a series of studies using a novel paradigm to address this problem directly, by interrogating the operation of decay and interference in short-term memory without rehearsal confounds. The results of these studies indicate that short-term memories are subject to very small decay effects with the mere passage of time but that interference plays a much larger role in their degradation. The authors discuss the implications of these results for existing models of memory decay and interference. PMID:19271849

  1. Short-term memory and dual task performance

    NASA Technical Reports Server (NTRS)

    Regan, J. E.

    1982-01-01

    Two hypotheses concerning the way in which short-term memory interacts with another task in a dual task situation are considered. It is noted that when two tasks are combined, the activity of controlling and organizing performance on both tasks simultaneously may compete with either task for a resource; this resource may be space in a central mechanism or general processing capacity or it may be some task-specific resource. If a special relationship exists between short-term memory and control, especially if there is an identity relationship between short-term and a central controlling mechanism, then short-term memory performance should show a decrement in a dual task situation. Even if short-term memory does not have any particular identity with a controlling mechanism, but both tasks draw on some common resource or resources, then a tradeoff between the two tasks in allocating resources is possible and could be reflected in performance. The persistent concurrence cost in memory performance in these experiments suggests that short-term memory may have a unique status in the information processing system.

  2. Multi-decadal climate variability, New South Wales, Australia.

    PubMed

    Franks, S W

    2004-01-01

    Traditional hydrological risk estimation has treated the observations of hydro-climatological extremes as being independent and identically distributed, implying a static climate risk. However, recent research has highlighted the persistence of multi-decadal epochs of distinct climate states across New South Wales (NSW), Australia. Climatological studies have also revealed multi-decadal variability in the magnitude and frequency of El Niño/Southern Oscillation (ENSO) impacts. In this paper, examples of multi-decadal variability are presented with regard to flood and drought risk. The causal mechanisms for the observed variability are then explored. Finally, it is argued that the insights into climate variability provide (a) useful lead time for forecasting seasonal hydrological risk, (b) a strong rationale for a new framework for hydrological design and (c) a strong example of natural climate variability for use in the testing of General Circulation Models of climate change. PMID:15195429

  3. Present and Future Modes of Low Frequency Climate Variability

    SciTech Connect

    Cane, Mark A.

    2014-02-20

    This project addressed area (1) of the FOA, “Interaction of Climate Change and Low Frequency Modes of Natural Climate Variability”. Our overarching objective is to detect, describe and understand the changes in low frequency variability between model simulations of the preindustrial climate and simulations of a doubled CO2 climate. The deliverables are a set of papers providing a dynamical characterization of interannual, decadal, and multidecadal variability in coupled models with attention to the changes in this low frequency variability between pre-industrial concentrations of greenhouse gases and a doubling of atmospheric concentrations of CO2. The principle mode of analysis, singular vector decomposition, is designed to advance our physical, mechanistic understanding. This study will include external natural variability due to solar and volcanic aerosol variations as well as variability internal to the climate system. An important byproduct is a set of analysis tools for estimating global singular vector structures from the archived output of model simulations.

  4. Disease in a more variable and unpredictable climate

    NASA Astrophysics Data System (ADS)

    McMahon, T. A.; Raffel, T.; Rohr, J. R.; Halstead, N.; Venesky, M.; Romansic, J.

    2014-12-01

    Global climate change is shifting the dynamics of infectious diseases of humans and wildlife with potential adverse consequences for disease control. Despite this, the role of global climate change in the decline of biodiversity and the emergence of infectious diseases remains controversial. Climate change is expected to increase climate variability in addition to increasing mean temperatures, making climate less predictable. However, few empirical or theoretical studies have considered the effects of climate variability or predictability on disease, despite it being likely that hosts and parasites will have differential responses to climatic shifts. Here we present a theoretical framework for how temperature variation and its predictability influence disease risk by affecting host and parasite acclimation responses. Laboratory experiments and field data on disease-associated frog declines in Latin America support this framework and provide evidence that unpredictable temperature fluctuations, on both monthly and diurnal timescales, decrease frog resistance to the pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd). Furthermore, the pattern of temperature-dependent growth of the fungus on frogs was inconsistent with the pattern of Bd growth in culture, emphasizing the importance of accounting for the host-parasite interaction when predicting climate-dependent disease dynamics. Consistent with our laboratory experiments, increased regional temperature variability associated with global El Niño climatic events was the best predictor of widespread amphibian losses in the genus Atelopus. Thus, incorporating the effects of small-scale temporal variability in climate can greatly improve our ability to predict the effects of climate change on disease.

  5. Impacts of climate change and variability on European agriculture: results of inventory analysis in COST 734 countries.

    PubMed

    Orlandini, Simone; Nejedlik, Pavol; Eitzinger, Josef; Alexandrov, Vesselin; Toulios, Leonidas; Calanca, Pierluigi; Trnka, Miroslav; Olesen, Jørgen E

    2008-12-01

    Climate plays a fundamental role in agriculture because of to its influence on production. All processes are regulated by specific climatic requirements. Furthermore, European agriculture, based on highly developed farming techniques, is mainly oriented to high quality food production that is more susceptible to meteorological hazards. These hazards can modify environment-genotype interactions, which can affect the quality of production. The COST 734 Action (Impacts of Climate Change and Variability on European Agriculture), launched in 2006, is composed of 28 signature countries and is funded by the European Commission. The main objective of the Action is the evaluation of possible impacts arising from climate change and variability on agriculture and the assessment of critical thresholds for various European areas. The Action will concentrate on four different tasks: agroclimatic indices and simulation models, including review and assessment of tools used to relate climate and agricultural processes; evaluation of the current trends of agroclimatic indices and model outputs, including remote sensing; developing and assessing future regional and local scenarios of agroclimatic conditions; and risk assessment and foreseen impacts on agriculture. The work will be carried out by respective Working Groups. This paper presents the results of the analysis of the first phase of inventory activity. Specific questionnaires were disseminated among COST 734 countries to collect information on climate change analysis, studies, and impact at the European level. The results were discussed with respect to their spatial distribution in Europe and to identify possible common long- and short-term strategies for adaptation. PMID:19076423

  6. Multi-Wheat-Model Ensemble Responses to Interannual Climate Variability

    NASA Technical Reports Server (NTRS)

    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

    2016-01-01

    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.

  7. Climate variability and change: a perspective from the oceania region

    NASA Astrophysics Data System (ADS)

    Beer, Tom

    2014-12-01

    This brief review identifies seven key science questions in relation to climate variability and change and examines recent research within the Australian and Pacific context: 1. How do the key processes controlling climate variability and predictability operate? 2. What are the nature and causes of regional climate anomalies, past variations in regional climate and extreme weather events and how will they change in the future? 3. How can we provide improved seasonal-to-interannual climate predictions? 4. What are the best projection methods? 5. What are the sea-level changes now and in the future; and how will these impact the coasts? 6. How to have significant benefits on climate service delivery and environmental management? 7. What are the best methods for assessing climate change risks, vulnerability and adaptation options?

  8. Interactions of Mean Climate Change and Climate Variability on Food Security Extremes

    NASA Technical Reports Server (NTRS)

    Ruane, Alexander C.; McDermid, Sonali; Mavromatis, Theodoros; Hudson, Nicholas; Morales, Monica; Simmons, John; Prabodha, Agalawatte; Ahmad, Ashfaq; Ahmad, Shakeel; Ahuja, Laj R.

    2015-01-01

    Recognizing that climate change will affect agricultural systems both through mean changes and through shifts in climate variability and associated extreme events, we present preliminary analyses of climate impacts from a network of 1137 crop modeling sites contributed to the AgMIP Coordinated Climate-Crop Modeling Project (C3MP). At each site sensitivity tests were run according to a common protocol, which enables the fitting of crop model emulators across a range of carbon dioxide, temperature, and water (CTW) changes. C3MP can elucidate several aspects of these changes and quantify crop responses across a wide diversity of farming systems. Here we test the hypothesis that climate change and variability interact in three main ways. First, mean climate changes can affect yields across an entire time period. Second, extreme events (when they do occur) may be more sensitive to climate changes than a year with normal climate. Third, mean climate changes can alter the likelihood of climate extremes, leading to more frequent seasons with anomalies outside of the expected conditions for which management was designed. In this way, shifts in climate variability can result in an increase or reduction of mean yield, as extreme climate events tend to have lower yield than years with normal climate.C3MP maize simulations across 126 farms reveal a clear indication and quantification (as response functions) of mean climate impacts on mean yield and clearly show that mean climate changes will directly affect the variability of yield. Yield reductions from increased climate variability are not as clear as crop models tend to be less sensitive to dangers on the cool and wet extremes of climate variability, likely underestimating losses from water-logging, floods, and frosts.

  9. Effect of interannual climate variability on carbon storage in Amazonian ecosystems

    USGS Publications Warehouse

    Tian, H.; Melillo, J.M.; Kicklighter, D.W.; McGuire, David A.; Helfrich, J. V. K., III; Moore, B., III; Vorosmarty, C.J.

    1998-01-01

    The Amazon Basin contains almost one-half of the world's undisturbed tropical evergreen forest as well as large areas of tropical savanna. The forests account for about 10 per cent of the world's terrestrial primary productivity and for a similar fraction of the carbon stored in land ecosystems, and short-term field measurements suggest that these ecosystems are globally important carbon sinks. But tropical land ecosystems have experienced substantial interannual climate variability owing to frequent El Nino episodes in recent decades. Of particular importance to climate change policy is how such climate variations, coupled with increases in atmospheric CO2 concentration, affect terrestrial carbon storage. Previous model analyses have demonstrated the importance of temperature in controlling carbon storage. Here we use a transient process-based biogeochemical model of terrestrial ecosystems to investigate interannual variations of carbon storage in undisturbed Amazonian ecosystems in response to climate variability and increasing atmospheric CO2 concentration during the period 1980 to 1994. In El Nino years, which bring hot, dry weather to much of the Amazon region, the ecosystems act as a source of carbon to the atmosphere (up to 0.2 petagrams of carbon in 1987 and 1992). In other years, these ecosystems act as a carbon sink (up to 0.7 Pg C in 1981 and 1993). These fluxes are large; they compare to a 0.3 Pg C per year source to the atmosphere associated with deforestation in the Amazon Basin in the early 1990s. Soil moisture, which is affected by both precipitation and temperature, and which affects both plant and soil processes, appears to be an important control on carbon storage.

  10. Climate variability and climate change vulnerability and adaptation. Workshop summary

    SciTech Connect

    Bhatti, N.; Cirillo, R.R.; Dixon, R.K.

    1995-12-31

    Representatives from fifteen countries met in Prague, Czech Republic, on September 11-15, 1995, to share results from the analysis of vulnerability and adaptation to global climate change. The workshop focused on the issues of global climate change and its impacts on various sectors of a national economy. The U.N. Framework Convention on Climate Change (FCCC), which has been signed by more than 150 governments worldwide, calls on signatory parties to develop and communicate measures they are implementing to respond to global climate change. An analysis of a country`s vulnerability to changes in the climate helps it identify suitable adaptation measures. These analyses are designed to determine the extent of the impacts of global climate change on sensitive sectors such as agricultural crops, forests, grasslands and livestock, water resources, and coastal areas. Once it is determined how vulnerable a country may be to climate change, it is possible to identify adaptation measures for ameliorating some or all of the effects.The objectives of the vulnerability and adaptation workshop were to: The objectives of the vulnerability and adaptation workshop were to: Provide an opportunity for countries to describe their study results; Encourage countries to learn from the experience of the more complete assessments and adjust their studies accordingly; Identify issues and analyses that require further investigation; and Summarize results and experiences for governmental and intergovernmental organizations.

  11. Short-term energy outlook: Quarterly projections. Second quarter 1995

    SciTech Connect

    1995-05-02

    The Energy Information Administration (EIA) prepares quarterly, short-term energy supply, demand, and price projections for publication in February, May, August, and November in the Short-Term Energy Outlook (Outlook). An annual supplement analyzes the performance of previous forecasts, compares recent projections with those of other forecasting services, and discusses current topics related to the short-term energy markets. (See Short-Term Energy Outlook Annual Supplement, DOE/EIA-0202.) The forecast period for this issue of the Outlook extends from the second quarter of 1995 through the fourth quarter of 1996. Values for the first quarter of 1995, however, are preliminary EIA estimates (for example, some monthly values for petroleum supply and disposition are derived in part from weekly data reported in the Weekly Petroleum Status Report) or are calculated from model simulations using the latest exogenous information available (for example, electricity sales and generation are simulated using actual weather data). The historical energy data, compiled into the second quarter 1995 version of the Short-Term Integrated Forecasting System (STIFS) database, are mostly EIA data regularly published in the Monthly Energy Review, Petroleum Supply Monthly, and other EIA publications. Minor discrepancies between the data in these publications and the historical data in this Outlook are due to independent rounding. The STIFS database is archived quarterly and is available from the National Technical Information Service.

  12. Language repetition and short-term memory: an integrative framework

    PubMed Central

    Majerus, Steve

    2013-01-01

    Short-term maintenance of verbal information is a core factor of language repetition, especially when reproducing multiple or unfamiliar stimuli. Many models of language processing locate the verbal short-term maintenance function in the left posterior superior temporo-parietal area and its connections with the inferior frontal gyrus. However, research in the field of short-term memory has implicated bilateral fronto-parietal networks, involved in attention and serial order processing, as being critical for the maintenance and reproduction of verbal sequences. We present here an integrative framework aimed at bridging research in the language processing and short-term memory fields. This framework considers verbal short-term maintenance as an emergent function resulting from synchronized and integrated activation in dorsal and ventral language processing networks as well as fronto-parietal attention and serial order processing networks. To-be-maintained item representations are temporarily activated in the dorsal and ventral language processing networks, novel phoneme and word serial order information is proposed to be maintained via a right fronto-parietal serial order processing network, and activation in these different networks is proposed to be coordinated and maintained via a left fronto-parietal attention processing network. This framework provides new perspectives for our understanding of information maintenance at the non-word-, word- and sentence-level as well as of verbal maintenance deficits in case of brain injury. PMID:23874280

  13. Impaired short-term memory for pitch in congenital amusia.

    PubMed

    Tillmann, Barbara; Lévêque, Yohana; Fornoni, Lesly; Albouy, Philippe; Caclin, Anne

    2016-06-01

    Congenital amusia is a neuro-developmental disorder of music perception and production. The hypothesis is that the musical deficits arise from altered pitch processing, with impairments in pitch discrimination (i.e., pitch change detection, pitch direction discrimination and identification) and short-term memory. The present review article focuses on the deficit of short-term memory for pitch. Overall, the data discussed here suggest impairments at each level of processing in short-term memory tasks; starting with the encoding of the pitch information and the creation of the adequate memory trace, the retention of the pitch traces over time as well as the recollection and comparison of the stored information with newly incoming information. These impairments have been related to altered brain responses in a distributed fronto-temporal network, associated with decreased connectivity between these structures, as well as in abnormalities in the connectivity between the two auditory cortices. In contrast, amusic participants׳ short-term memory abilities for verbal material are preserved. These findings show that short-term memory deficits in congenital amusia are specific to pitch, suggesting a pitch-memory system that is, at least partly, separated from verbal memory. This article is part of a Special Issue entitled SI: Auditory working memory. PMID:26505915

  14. Food Prices and Climate Extremes: A Model of Global Grain Price Variability with Storage

    NASA Astrophysics Data System (ADS)

    Otto, C.; Schewe, J.; Frieler, K.

    2015-12-01

    Extreme climate events such as droughts, floods, or heat waves affect agricultural production in major cropping regions and therefore impact the world market prices of staple crops. In the last decade, crop prices exhibited two very prominent price peaks in 2007-2008 and 2010-2011, threatening food security especially for poorer countries that are net importers of grain. There is evidence that these spikes in grain prices were at least partly triggered by actual supply shortages and the expectation of bad harvests. However, the response of the market to supply shocks is nonlinear and depends on complex and interlinked processes such as warehousing, speculation, and trade policies. Quantifying the contributions of such different factors to short-term price variability remains difficult, not least because many existing models ignore the role of storage which becomes important on short timescales. This in turn impedes the assessment of future climate change impacts on food prices. Here, we present a simple model of annual world grain prices that integrates grain stocks into the supply and demand functions. This firstly allows us to model explicitly the effect of storage strategies on world market price, and thus, for the first time, to quantify the potential contribution of trade policies to price variability in a simple global framework. Driven only by reported production and by long--term demand trends of the past ca. 40 years, the model reproduces observed variations in both the global storage volume and price of wheat. We demonstrate how recent price peaks can be reproduced by accounting for documented changes in storage strategies and trade policies, contrasting and complementing previous explanations based on different mechanisms such as speculation. Secondly, we show how the integration of storage allows long-term projections of grain price variability under climate change, based on existing crop yield scenarios.

  15. The Dynamics of Ocean Climate Variability.

    ERIC Educational Resources Information Center

    White, Warren B.; Haney, Robert L.

    1978-01-01

    Halfway through a five-year experimental program designed to test classical concepts of ocean/atmosphere climate dynamics, researchers are finding that the theories may conflict with new data on disturbances in the ocean thermal structure. (Author BB)

  16. Verbal short-term memory and vocabulary learning in polyglots.

    PubMed

    Papagno, C; Vallar, G

    1995-02-01

    Polyglot and non-polyglot Italian subjects were given tests assessing verbal (phonological) and visuo-spatial short-term and long-term memory, general intelligence, and vocabulary knowledge in their native language. Polyglots had a superior level of performance in verbal short-term memory tasks (auditory digit span and nonword repetition) and in a paired-associate learning test, which assessed the subjects' ability to acquire new (Russian) words. By contrast, the two groups had comparable performance levels in tasks assessing general intelligence, visuo-spatial short-term memory and learning, and paired-associate learning of Italian words. These findings, which are in line with neuropsychological and developmental evidence, as well as with data from normal subjects, suggest a close relationship between the capacity of phonological memory and the acquisition of foreign languages. PMID:7754088

  17. Short-Termed Integrated Forecasting System: 1993 Model documentation report

    SciTech Connect

    Not Available

    1993-05-01

    The purpose of this report is to define the Short-Term Integrated Forecasting System (STIFS) and describe its basic properties. The Energy Information Administration (EIA) of the US Energy Department (DOE) developed the STIFS model to generate short-term (up to 8 quarters), monthly forecasts of US supplies, demands, imports exports, stocks, and prices of various forms of energy. The models that constitute STIFS generate forecasts for a wide range of possible scenarios, including the following ones done routinely on a quarterly basis: A base (mid) world oil price and medium economic growth. A low world oil price and high economic growth. A high world oil price and low economic growth. This report is written for persons who want to know how short-term energy markets forecasts are produced by EIA. The report is intended as a reference document for model analysts, users, and the public.

  18. Short-Term Resilience Processes in the Family

    PubMed Central

    Bai, Sunhye; Repetti, Rena L.

    2015-01-01

    The authors review naturalistic studies of short-term processes that appear to promote resilience in children in the context of everyday family life and argue that warm and supportive family interactions foster resilience through their cumulative impact on children’s emotional and physiological stress response systems. In the short-term, these family interactions promote the experience and expression of positive emotion and healthy patterns of diurnal cortisol. Over time, these internal resources – a propensity to experience positive emotion and a well-functioning hypothalamic-pituitary-adrenal axis system –enhance a child’s capacity to avoid, or limit, the deleterious effects of adversity. This article highlights naturalistic research methods that are well suited to the study of these short-term resilience processes and points to clinical applications of our conceptual and methodological approach. PMID:26246651

  19. Reconstructing Clusters for Preconditioned Short-term Load Forecasting

    NASA Astrophysics Data System (ADS)

    Itagaki, Tadahiro; Mori, Hiroyuki

    This paper presents a new preconditioned method for short-term load forecasting that focuses on more accurate predicted value. In recent years, the deregulated and competitive power market increases the degree of uncertainty. As a result, more sophisticated short-term load forecasting techniques are required to deal with more complicated load behavior. To alleviate the complexity of load behavior, this paper presents a new preconditioned model. In this paper, clustering results are reconstructed to equalize the number of learning data after clustering with the Kohonen-based neural network. That enhances a short-term load forecasting model at each reconstructed cluster. The proposed method is successfully applied to real data of one-step ahead daily maximum load forecasting.

  20. Climate variability of Late Pleistocene deglaciation in the North American midcontinent derived from tree rings

    NASA Astrophysics Data System (ADS)

    Panyushkina, Irina P.; Livina, Valerie N.; Leavitt, Steve W.; Mode, William N.

    2016-04-01

    High-resolution climatic proxies, such as tree rings spanning millennia, have excellent potential to describe high- and low-frequency variability of climate. In practice, however, although the number of Holocene millennium-length tree-ring records is still rather limited, they are especially rare for the Late Pleistocene warming period following the Last Glacial Maximum. Furthermore, detection of climatic variability in tree-ring data is hindered due to intricate methodology of chronology development that transforms changes in tree geometry and a variety of environmental responses of tree growth to a climatic signal. Following meticulous derivation of a new tree-ring chronology, we propose a novel approach to analyze annual, decadal, multi-decadal and centennial climate-related variability of floating tree rings dated back near the end of the Pleistocene. We have developed a 1400-year tree-ring width chronology of spruce from the Green Bay area (Wisconsin) dated from 14.5 ka to 13.1ka cal BP. This new North American midcontinent record is composed of 10 overlapped site chronologies and has two short gaps filled with linear interpolation. The Green Bay chronology covers most of the warm and moist Bølling-Allerød interstadial (14.7 ka -12.7 ka BP). Within the Bølling-Allerød interstadial, there were several abrupt and brief cooling excursions such as the Older Dryas with full-glacial-like temperature conditions. We have applied tipping point analysis to detect the changes of climate-system states during these turbulent times and obtained early warning signals in the tree-ring variance. The analysis detected four short-term bifurcations dated ca. 14,450 cal BP, 14,000 cal BP, 13,750-13,600 cal BP and 13,180-13,100 cal BP. The bifurcation events of the tree-ring record correspond well to the abrupt and short cooling temperature excursions of the Bølling-Allerød interstadial documented in δ18O and Ca of GRIP ice-core records, and the Laurentide ice sheet dynamics

  1. Impact of Holocene climate variability on Arctic vegetation

    NASA Astrophysics Data System (ADS)

    Gajewski, K.

    2015-10-01

    This paper summarizes current knowledge about the postglacial history of the vegetation of the Canadian Arctic Archipelago (CAA) and Greenland. Available pollen data were used to understand the initial migration of taxa across the Arctic, how the plant biodiversity responded to Holocene climate variability, and how past climate variability affected primary production of the vegetation. Current evidence suggests that most of the flora arrived in the area during the Holocene from Europe or refugia south or west of the region immediately after local deglaciation, indicating rapid dispersal of propagules to the region from distant sources. There is some evidence of shrub species arriving later in Greenland, but it is not clear if this is dispersal limited or a response to past climates. Subsequent climate variability had little effect on biodiversity across the CAA, with some evidence of local extinctions in areas of Greenland in the late Holocene. The most significant impact of climate changes is on vegetation density and/or plant production.

  2. Short- term effects of silvicultural treatment on net nitrogen mineralization in a Mediterranean oak forest

    NASA Astrophysics Data System (ADS)

    Bautista, Inmaculada; Lull, Cristina; Lidón, Antonio; González-Sanchis, María; del Campo, Antonio

    2014-05-01

    Forest productivity is strongly linked to nitrogen (N) uptake and N net mineralization. Under Mediterranean climate, soil water content and soil biological activity are highly variable. This determines the N availability, which is restricted by low soil water content in summer and low temperature in winter. Silvicultural treatments often alter nutrient fluxes inducing changes in environmental conditions and biological activity. The aim of the study is to examine the short term responses of soil carbon (C) and N to a thinning treatment. The study site is a marginal oak forest located in Valencia (East of Spain).Two contiguous plots, control and treatment, of 1800 m2 area, respectively, were selected. The orientation (NW), slope (30 %) and initial forest density (861 tree per ha) were the same for both plots. Treatment plot was thinned on May, 2012, following the forest manager's requirements, reducing the forest density from 861 to 414 tree per ha. Control plot was not thinned. Net nitrogen mineralization, net nitrification and nitrogen leaching under 15 cm depth were determined by in situ measurements in both, thinned and control plots, using the resin-core method. Soil samples were uniformly distributed along the slope (top, middle and bottom). Cores were replaced every two months to obtain seasonal variation of nitrogen mineralization along the year. Furthermore, laboratory respiration, soluble organic carbon (SOC) and microbial biomass carbon (MBC) evolution were also estimated in the soil used in the field incubations. Soil water content and temperature at 5 cm depth were continuously recorded using FDR sensors (EC-TM, Decagon Devices Inc., Pullman, WA) connected to several ECHO2 (Decagon) data-loggers . All the biological parameters measured significantly varied along the year. In general, higher values of SOC and MBC were found in the thinned plot samples, but differences were not statistically significant. A significant effect of the thinning was found in

  3. Short-term tocolytics for preterm delivery – current perspectives

    PubMed Central

    Haas, David M; Benjamin, Tara; Sawyer, Renata; Quinney, Sara K

    2014-01-01

    Administration of short-term tocolytic agents can prolong pregnancy for women in preterm labor. Prolonging pregnancy has many benefits because it allows for other proven interventions, such as antenatal corticosteroid administration, to be accomplished. This review provides an overview of currently utilized tocolytic agents and the evidence demonstrating their efficacy for prolonging pregnancy by at least 48 hours. General pharmacological principles for the clinician regarding drugs in pregnancy are also briefly discussed. In general, while the choice of the best first-line short-term tocolytic drug is not clear, it is evident that use of these agents has a clear place in current obstetric therapeutics. PMID:24707187

  4. Mechanisms of long and short term immunity to plague.

    PubMed Central

    Wake, A; Morita, H; Wake, M

    1978-01-01

    Long and short term immunity to plague was produced in normal mice by using, respectively, an antibiotic resistant Yersinia pestis and Yersinia pseudotuberculosis. Both immunogens were used live. Passive serum transfer experiments, together with assays for the bactericidal activity of macrophages and delayed hypersensitivity tests, showed that the short term immunity was of a humoral nature and the long term immunity was cell mediated. The plague virulence markers of the two immunogens were: Y. pestis VW- F1+ P1+ P+; Y. pseudotuberculosis VW+ F1- P1- P-. The challenge organism was Y. pestis VW+ F1+ P1+ P+. Images Figure 3 PMID:680791

  5. Predicting short-term stock fluctuations by using processing fluency

    PubMed Central

    Alter, Adam L.; Oppenheimer, Daniel M.

    2006-01-01

    Three studies investigated the impact of the psychological principle of fluency (that people tend to prefer easily processed information) on short-term share price movements. In both a laboratory study and two analyses of naturalistic real-world stock market data, fluently named stocks robustly outperformed stocks with disfluent names in the short term. For example, in one study, an initial investment of $1,000 yielded a profit of $112 more after 1 day of trading for a basket of fluently named shares than for a basket of disfluently named shares. These results imply that simple, cognitive approaches to modeling human behavior sometimes outperform more typical, complex alternatives. PMID:16754871

  6. Land Use and Climate Variability Amplify Contaminant Pulses

    EPA Science Inventory

    Converting land to human-dominated uses has increased contaminant loads in streams and rivers and vastly transformed hydrological cycles (Vitousek et al. 1997). More recently, climate change has further altered hydrologic cycles and variability of precipitation (IPCC 2007). Toge...

  7. Differential effects of reciprocity and attitude similarity across long- versus short-term mating contexts.

    PubMed

    Lehr, Andrew T; Geher, Glenn

    2006-08-01

    Participants were 24 male and 32 female undergraduate and graduate students whom the authors recruited for an examination of the effects of attitude similarity and reciprocity on the degree of attraction toward potential mates. The authors examined the effects of these 2 variables on degree of liking in long-term and short-term contexts. The authors administered a vignette about a bogus stranger to each participant, varying the stranger's attitude similarity with and liking of the participant. The authors enclosed the vignette in a folder that described the stranger as having either very similar or very different attitudes from the participant and that included a passage that notified the participant that the stranger either likes or does not like him or her. The dependent variables included 4 indexes of the extent to which participants reported liking the bogus stranger: a scale that measured short-term mating items, a scale that measured long-term mating items, a degree-of-liking scale, and a behavioral-intention item. Across these 4 attraction-relevant dependent variables, the authors found significant main effects of the reciprocity variable. Also, the authors found a significant main effect of attitude similarity on the likability measure. The authors found significant main effects of reciprocity in a long-term mating context and a short-term mating context. PMID:16894702

  8. Impact of climate variability on vector-borne disease transmission

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We will discuss the impact of climate variability on vector borne diseases and demonstrate that global climate teleconnections can be used to anticipate and forecast, in the case of Rift Valley fever, epidemics and epizootics. In this context we will examine significant worldwide weather anomalies t...

  9. Visual Motor Short Term Memory in Educationally Subnormal Boys.

    ERIC Educational Resources Information Center

    Sugden, D. A.

    1978-01-01

    This investigation attempted to describe the developmental sequence of visual motor short term memory in mentally handicapped boys (mental ages 6, 9, and 12) during conditions of rest and interpolated activity, and to explore their use of spontaneous rehearsal strategies. Results are compared with those for normal boys. (Author/SJL)

  10. Labeling, Rehearsal, and Short-Term Memory in Retarded Children

    ERIC Educational Resources Information Center

    Hagen, John W.; And Others

    1974-01-01

    A short-term memory task was used to explore the effects of verbal labeling and rehearsal on serial-position recall in mildly retarded 9-to 11-year-old children. Results support the view that verbal skills affect recall in mildly retarded children similarly to normal children. (Author/SDH)

  11. Visual Short-Term Memory During Smooth Pursuit Eye Movements

    ERIC Educational Resources Information Center

    Kerzel, Dirk; Ziegler, Nathalie E.

    2005-01-01

    Visual short-term memory (VSTM) was probed while observers performed smooth pursuit eye movements. Smooth pursuit keeps a moving object stabilized in the fovea. VSTM capacity for position was reduced during smooth pursuit compared with a condition with eye fixation. There was no difference between a condition in which the items were approximately…

  12. Validation of a Fish Short-term Reproduction Assay

    EPA Science Inventory

    The Fish Short-term Reproduction Assay is an in vivo assay conducted with fathead minnows and is designed to detect changes in spawning, gross morphology, histopathology, and specific biochemical endpoints that reflect disturbances in the hypothalamic-pituitary-gonadal (HPG) axis...

  13. Interference-Based Forgetting in Verbal Short-Term Memory

    ERIC Educational Resources Information Center

    Lewandowsky, Stephan; Geiger, Sonja M.; Oberauer, Klaus

    2008-01-01

    This article presents four experiments that tested predictions of SOB (Serial Order in a Box), an interference-based theory of short-term memory. Central to SOB is the concept of novelty-sensitive encoding, which holds that items are encoded to the extent that they differ from already-encoded information. On the additional assumption that…

  14. CONTROLLED, SHORT-TERM DERMAL AND INHALATION EXPOSURE TO CHLOROFORM

    EPA Science Inventory

    Studies were conducted to determine the uptake by humans of chloroform as a result of controlled short-term dermal and inhalation exposures. The approach used continuous real-time breath analysis to determine exhaled-breath profiles and evaluate chloroform kinetics in the huma...

  15. A DAPHNIA MAGNA SHORT-TERM SURVIVAL AND GROWTH TEST

    EPA Science Inventory

    With the change in acceptable test temperatures for invertebrate toxicity tests from <20oC to 25oC, it is now possible to use Daphnia magna for short-term chronic testing. When cultured at 25oC the dry weight of <24 hr old D. magna ranges from 7 to 15 g depending upon nutrition,...

  16. The Role of Short-Term Memory on Language Learning.

    ERIC Educational Resources Information Center

    Wang, Li-Yuch

    Two studies assessed the impact of short-term memory on English as a Second Language learning. The first involved 20 graduate students at a Taiwanese university, who were randomly divided into treatment and control groups. It investigated differences in the performance of phrase recollection when the information was chunked versus unchunked.…

  17. Valuing Short-Term Study Abroad in Business

    ERIC Educational Resources Information Center

    Loh, Chung-Ping A.; Steagall, Jeffrey W.; Gallo, Andres; Michelman, Jeffrey E.

    2011-01-01

    Short-term study abroad courses often claim to provide a unique experience for students, but it is not clear how the value translates into a dollar amount. The paper uses the contingent valuation method to assess participating students' pre- and post-trip perceived dollar value of their study abroad courses at an AACSB accredited business school.…

  18. Short Term Skill Training. Alternative Approaches. Information Series No. 222.

    ERIC Educational Resources Information Center

    Paulsen, Russell

    Short term skill training programs are those programs, usually one year or less, designed to train, retrain, or upgrade the skills of workers. Such programs provide an opportunity for postsecondary vocational institutions to respond to the human resource needs of their communities. A number of important policy issues are involved in the provision…

  19. Short-Term Memory, Executive Control, and Children's Route Learning

    ERIC Educational Resources Information Center

    Purser, Harry R. M.; Farran, Emily K.; Courbois, Yannick; Lemahieu, Axelle; Mellier, Daniel; Sockeel, Pascal; Blades, Mark

    2012-01-01

    The aim of this study was to investigate route-learning ability in 67 children aged 5 to 11 years and to relate route-learning performance to the components of Baddeley's model of working memory. Children carried out tasks that included measures of verbal and visuospatial short-term memory and executive control and also measures of verbal and…

  20. Regularization in Short-Term Memory for Serial Order

    ERIC Educational Resources Information Center

    Botvinick, Matthew; Bylsma, Lauren M.

    2005-01-01

    Previous research has shown that short-term memory for serial order can be influenced by background knowledge concerning regularities of sequential structure. Specifically, it has been shown that recall is superior for sequences that fit well with familiar sequencing constraints. The authors report a corresponding effect pertaining to serial…

  1. Short-term storage of Atlantic sturgeon spermatozoa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is significant interest to restore the Atlantic sturgeon, a species of concern. Biologists are interested in both the short-term storage and cryopreservation of semen to maximize availability of viable spermatozoa whenever a rare ripe female is found and available for spawning. We conducted sh...

  2. Short-term storage options for fresh-market onions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sweet onions have proven to be an excellent spring specialty crop in southeastern Oklahoma. Growers are interested in fuel-efficient methods of short term storage (up to 6 months) to lengthen market windows and enhance returns. Onions were seeded in high tunnels in November of 2005, transplanted to...

  3. 22 CFR 62.21 - Short-term scholars.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... participate in seminars, workshops, conferences, study tours, professional meetings, or similar types of... shall satisfy the definition of a short-term scholar as set forth in § 62.4. (e) Cross-cultural... shall be exempted from the requirements of providing cross-cultural activities and orientation as...

  4. 22 CFR 62.21 - Short-term scholars.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... participate in seminars, workshops, conferences, study tours, professional meetings, or similar types of... shall satisfy the definition of a short-term scholar as set forth in § 62.4. (e) Cross-cultural... shall be exempted from the requirements of providing cross-cultural activities and orientation as...

  5. 22 CFR 62.21 - Short-term scholars.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... participate in seminars, workshops, conferences, study tours, professional meetings, or similar types of... shall satisfy the definition of a short-term scholar as set forth in § 62.4. (e) Cross-cultural... shall be exempted from the requirements of providing cross-cultural activities and orientation as...

  6. Short-term energy outlook, Quarterly projections. Third quarter 1993

    SciTech Connect

    1993-08-04

    The Energy Information Administration (EIA) prepares quarterly, short-term energy supply, demand, and price projections for publication in February, May, August, and November in the Short-Term Energy Outlook (Outlook). An annual supplement analyzes the performance of previous forecasts, compares recent cases with those of other forecasting services, and discusses current topics related to the short-term energy markets. (See Short-Term Energy Outlook Annual Supplement, DOE/EIA-0202.) The forecast period for this issue of the Outlook extends from the third quarter of 1993 through the fourth quarter of 1994. Values for the second quarter of 1993, however, are preliminary EIA estimates (for example, some monthly values for petroleum supply and disposition are derived in part from weekly data reported in the Weekly Petroleum Status Report) or are calculated from model simulations using the latest exogenous information available (for example, electricity sales and generation are simulated using actual weather data). The historical energy data are EIA data published in the Monthly Energy Review, Petroleum Supply Monthly, and other EIA publications. Minor discrepancies between the data in these publications and the historical data in this Outlook are due to independent rounding.

  7. Facilitation and Distraction in Short-Term Memory.

    ERIC Educational Resources Information Center

    Hagen, John William; Kail, Robert V., Jr.

    Children's short-term memory was studied under two experimental conditions: one in which recall was expected to be facilitated because of the provision of a study period, and one in which a distracting task was imposed that was expected to interfere with recall. Forty subjects at each of two age levels, 7 and 11 years, were tested in a…

  8. A Short Term Real Time Study in Syntactic Change.

    ERIC Educational Resources Information Center

    Duarte, Maria Eugenia Lamoglia

    Recent research has shown that Brazilian Portuguese is undergoing a change regarding the null subject parameter, evolving from a null subject to a non-null subject language. This paper presents the results of a short term, real time study of speakers of Brazilian Portuguese with low and mid levels of formal education. The study was based on…

  9. SHORT-TERM MEMORY IS INDEPENDENT OF BRAIN PROTEIN SYNTHESIS

    SciTech Connect

    Davis, Hasker P.; Rosenzweig, Mark R.; Jones, Oliver W.

    1980-09-01

    Male Swiss albino CD-1 mice given a single injection of a cerebral protein synthesis inhibitor, anisomycin (ANI) (1 mg/animal), 20 min prior to single trial passive avoidance training demonstrated impaired retention at tests given 3 hr, 6 hr, 1 day, and 7 days after training. Retention was not significantly different from saline controls when tests were given 0.5 or 1.5 hr after training. Prolonging inhibition of brain protein synthesis by giving either 1 or 2 additional injections of ANI 2 or 2 and 4 hr after training did not prolong short-term retention performance. The temporal development of impaired retention in ANI treated mice could not be accounted for by drug dosage, duration of protein synthesis inhibition, or nonspecific sickness at test. In contrast to the suggestion that protein synthesis inhibition prolongs short-term memory (Quinton, 1978), the results of this experiment indicate that short-term memory is not prolonged by antibiotic drugs that inhibit cerebral protein synthesis. All evidence seems consistent with the hypothesis that short-term memory is protein synthesis independent and that the establishment of long-term memory depends upon protein synthesis during or shortly after training. Evidence for a role of protein synthesis in memory maintenance is discussed.

  10. An Evaluation of Short-Term Distributed Online Learning Events

    ERIC Educational Resources Information Center

    Barker, Bradley; Brooks, David

    2005-01-01

    The purpose of this study was to evaluate the effectiveness of short-term distributed online training events using an adapted version of the compressed evaluation form developed by Wisher and Curnow (1998). Evaluating online distributed training events provides insight into course effectiveness, the contribution of prior knowledge to learning, and…

  11. A Short-Term Dynamic Psychotherapy Approach for College Students

    ERIC Educational Resources Information Center

    Carlson, Thomas M.

    2004-01-01

    This article explores the need for university counseling centers (UCCs) to implement brief therapies and describes one such treatment, intensive short-term dynamic psychotherapy (ISTDP), as a particularly viable therapeutic approach in this setting. Because ISTDP is not appropriate for all students seeking therapy, a careful assessment of the…

  12. Improving creativity performance by short-term meditation

    PubMed Central

    2014-01-01

    Background One form of meditation intervention, the integrative body-mind training (IBMT) has been shown to improve attention, reduce stress and change self-reports of mood. In this paper we examine whether short-term IBMT can improve performance related to creativity and determine the role that mood may play in such improvement. Methods Forty Chinese undergraduates were randomly assigned to short-term IBMT group or a relaxation training (RT) control group. Mood and creativity performance were assessed by the Positive and Negative Affect Schedule (PANAS) and Torrance Tests of Creative Thinking (TTCT) questionnaire respectively. Results As predicted, the results indicated that short-term (30 min per day for 7 days) IBMT improved creativity performance on the divergent thinking task, and yielded better emotional regulation than RT. In addition, cross-lagged analysis indicated that both positive and negative affect may influence creativity in IBMT group (not RT group). Conclusions Our results suggested that emotion-related creativity-promoting mechanism may be attributed to short-term meditation. PMID:24645871

  13. Short-Term Effects of Playing Computer Games on Attention

    ERIC Educational Resources Information Center

    Tahiroglu, Aysegul Yolga; Celik, Gonca Gul; Avci, Ayse; Seydaoglu, Gulsah; Uzel, Mehtap; Altunbas, Handan

    2010-01-01

    Objective: The main aim of the present study is to investigate the short-term cognitive effects of computer games in children with different psychiatric disorders and normal controls. Method: One hundred one children are recruited for the study (aged between 9 and 12 years). All participants played a motor-racing game on the computer for 1 hour.…

  14. Exogenous Attention Influences Visual Short-Term Memory in Infants

    ERIC Educational Resources Information Center

    Ross-Sheehy, Shannon; Oakes, Lisa M.; Luck, Steven J.

    2011-01-01

    Two experiments examined the hypothesis that developing visual attentional mechanisms influence infants' Visual Short-Term Memory (VSTM) in the context of multiple items. Five- and 10-month-old infants (N = 76) received a change detection task in which arrays of three differently colored squares appeared and disappeared. On each trial one square…

  15. Short-term energy outlook. Quarterly projections, second quarter 1996

    SciTech Connect

    1996-04-01

    The Energy Information Administration prepares quarterly, short-term energy supply, demand, and price projections. The forecasts in this issue cover the second quarter of 1996 through the fourth quarter of 1997. Changes to macroeconomic measures by the Bureau of Economic Analysis have been incorporated into the STIFS model used.

  16. Short-Term Energy Outlook: Quarterly projections. Fourth quarter 1993

    SciTech Connect

    Not Available

    1993-11-05

    The Energy Information Administration (EIA) prepares quarterly, short-term energy supply, demand, and price projections for publication in February, May, August, and November in the Short-Term Energy Outlook (Outlook). An annual supplement analyzes the performance of previous forecasts, compares recent cases with those of other forecasting services, and discusses current topics related to the short-term energy markets. (See Short-Term Energy Outlook Annual Supplement, DOE/EIA-0202.) The forecast period for this issue of the Outlook extends from the fourth quarter of 1993 through the fourth quarter of 1994. Values for the third quarter of 1993, however, are preliminary EIA estimates (for example, some monthly values for petroleum supply and disposition are derived in part from weekly data reported in the Weekly Petroleum Status Report) or are calculated from model simulations using the latest exogenous information available (for example, electricity sales and generation are simulated using actual weather data). The historical energy data are EIA data published in the Monthly Energy Review, Petroleum Supply Monthly, and other EIA publications.

  17. Short-Term Reducing Conditions Decreases Soil Aggregation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Upland soils in Midwestern US are often ponded during the spring for days or weeks and may undergo reducing state. Short-term reducing conditions change the chemistry of the soil and that may affect soil aggregation. The objective of this paper was to determine how changes in the redox status of the...

  18. Emotive-reconstruction psychotherapy: a short-term cognitive approach.

    PubMed

    Morrison, J K; Cometa, M S

    1977-04-01

    Emotive-Reconstructive Therapy, a recently developed therapeutic modality deriving from cognitive theory, may be a promising short-term approach to psychopathology. Combining the use of imagery with selective hyperventilation, a therapist induces patients to reexperience past events, and subsequently to radically reconstrue themselves and significant others in a personally satisfying direction. PMID:879383

  19. Relation between Intelligence and Short-Term Memory

    ERIC Educational Resources Information Center

    Cohen, Ronald L.; Sandberg, Tor

    1977-01-01

    Intelligence and short-term memory correlations in children were measured using probed serial recall of supraspan digit lists. Results showed the predictive power of intelligence to range from a maximum in the case of recall for recency items to practically zero in the case of primacy items. (Author/MV)

  20. Color Cues and Rehearsal in Short-Term Memory.

    ERIC Educational Resources Information Center

    Sabo, Ruth A.; Hagen, John W.

    A short term memory task was used to explore the effects of color cues and of a condition that permitted rehearsal as compared to one that did not. Eighty subjects per grade at grades 3, 5, and 7 were tested. A stimulus array consisted of five cards, each of which contained pictures that could be designated as central or incidental. The stimulus…

  1. PROTOCOLS FOR SHORT TERM TOXICITY SCREENING OF HAZARDOUS WASTE SITES

    EPA Science Inventory

    The manual contains short-term methods for measuring the toxicity of chemical contaminants in soil, sediment, surface water, and groundwater samples. The algal assay is a chronic test, while all other tests described in the manual are acute tests. The methods are one of several t...

  2. Human Responses to Climate Variability: The Case of South Africa

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  3. CLIMATE VARIABILITY, CHANGE, AND CONSEQUENCES IN ESTUARIES

    EPA Science Inventory

    Climate change operates at global, hemispheric, and regional scales, sometimes involving rapid shifts in ocean and atmospheric circulation. Changes of global scope occurred in the transition into the Little Ice Age (1350-1880) and subsequent warming during the 20th century. In th...

  4. Chances of short-term cooling trends over Canada for the next decades

    NASA Astrophysics Data System (ADS)

    Grenier, Patrick; de Elia, Ramon; Chaumont, Diane

    2014-05-01

    As climate services continue to develop in Quebec, Canada, an increasing number of requests are made for providing information relevant for the near term. As a response, one approach has been to consider short-term cooling trends as a basis for climate products. This project comprises different aspects: technical steps, knowledge transfer, and societal use. Each step does represent a different challenge. The technical part, i.e. producing probabilistic distributions of short-term temperature trends, involves relatively complex scenario construction methods including bias-related post-processing, and access to wide simulation and observation databases. Calculations are performed on 60 CMIP5-based scenarios on a grid covering Canada during the period 2006-2035, and for 5, 10, 15, 20 and 25-year trend durations. Knowledge transfer implies overcoming misinterpretation, given that probabilistic projections based on simulation ensembles are not perfectly related to real-Earth possible outcomes. Finally, societal use of this information remains the biggest challenge. On the one hand, users clearly state their interest in near-term relevant information, and intuitively it seems clear that short-term cooling trends embedded within the long-term warming path should be considered in adaptation plans, for avoiding over-adaptation. On the other hand, the exact way of incorporating such information within a decision-making process has proven not to be obvious. Irrespective of that, the study and communication of short-term cooling chances is necessary for preventing decision-makers to infer from the eventual occurrence of such a trend that global warming isn't happening. The presentation will discuss the three aspects aforementioned.

  5. The Variable Climate Impact of Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Graf, H.

    2011-12-01

    The main effect of big volcanic eruptions in the climate system is due to their efficient transport of condensable gases and their precursors into the stratosphere. There the formation of aerosols leads to effects on atmospheric radiation transfer inducing a reduction of incoming solar radiation by reflection (i.e. cooling of the Earth surface) and absorption of near infrared radiation (i.e. heating) in the aerosol laden layers. In the talk processes determining the climate effect of an eruption will be illustrated by examples, mainly from numerical modelling. The amount of gases released from a magma during an eruption and the efficiency of their transport into very high altitudes depends on the geological setting (magma type) and eruption style. While mid-sized eruption plumes of Plinian style quickly can develop buoyancy by entrainment of ambient air, very large eruptions with high magma flux rates often tend to collapsing plumes and co-ignimbrite style. These cover much bigger areas and are less efficient in entraining ambient air. Vertical transport in these plumes is chaotic and less efficient, leading to lower neutral buoyancy height and less gas and particles reaching high stratospheric altitudes. Explosive energy and amount of released condensable gases are not the only determinants for the climatic effect of an eruption. The effect on shortwave radiation is not linear with the amount of aerosols formed since according to the Lambert-Beer Law atmospheric optical depth reaches a saturation limit with increased absorber concentration. In addition, if more condensable gas is available for aerosol growth, particles become larger and this affects their optical properties to less reflection and more absorption. Larger particles settle out faster, thus reducing the life time of the aerosol disturbance. Especially for big tropical eruptions the strong heating of the stratosphere in low latitudes leads to changes in atmospheric wave propagation by strengthened

  6. Does internal climate variability impact radiative feedback estimates?

    NASA Astrophysics Data System (ADS)

    Jonko, A. K.

    2013-12-01

    A lot of attention has been focussed on the inter-model spread in equilibrium climate sensitivity and the radiative feedbacks that contribute to it as a measure of our uncertainty of the climate system's response to external forcing. But how accurate is an estimate of this uncertainty derived purely from model-to-model differences? Recent work has highlighted the importance of factors such as differences resulting from methodology (Klocke et al., 2013) as well as internal climate variability (Deser et al., 2012), which have historically not been included in multi-model assessments. While an increasing number of models participating in Coupled Model Intercomparison Projects (CMIP) provide several ensemble members for certain simulations, the ensemble sizes are generally not large enough to fully sample climate's intrinsic variability. Here we use a large 40 member ensemble of simulations performed with the National Center for Atmospheric Research Community Climate System Model Version 3 to asses the impact of internal variability on radiative feedback estimates. We find that the spread in individual feedbacks among ensemble members corresponds to 25% of CMIP3 inter-model spread. Deser, C., A. Phillips, V. Bourdette and H. Teng (2012): Uncertainty in climate change projections: the role of internal variability, Clim. Dyn., 38, 527-546. Klocke, D., J. Quaas and B. Stevens (2013): Assessment of different metrics for physical climate feedbacks, Clim. Dyn., DOI 10.1007/s00382-013-1757-1

  7. Women's role in adapting to climate change and variability

    NASA Astrophysics Data System (ADS)

    Carvajal-Escobar, Y.; Quintero-Angel, M.; García-Vargas, M.

    2008-04-01

    Given that women are engaged in more climate-related change activities than what is recognized and valued in the community, this article highlights their important role in the adaptation and search for safer communities, which leads them to understand better the causes and consequences of changes in climatic conditions. It is concluded that women have important knowledge and skills for orienting the adaptation processes, a product of their roles in society (productive, reproductive and community); and the importance of gender equity in these processes is recognized. The relationship among climate change, climate variability and the accomplishment of the Millennium Development Goals is considered.

  8. Climate driven variability and detectability of temporal trends in low flow indicators for Ireland

    NASA Astrophysics Data System (ADS)

    Hall, Julia; Murphy, Conor; Harrigan, Shaun

    2013-04-01

    Observational data from hydrological monitoring programs plays an important role in informing decision makers of changes in key hydrological variables. To analyse how changes in climate influence stream flow, undisturbed river basins with near-natural conditions limited from human influences are needed. This study analyses low flow indicators derived from observations from the Irish Reference Network. Within the trend analysis approach the influence of individual years or sub-periods on the detected trend are analysed using sequential trend tests on all possible periods (of at least 10 years in length) by varying the start and end dates of records for various indicators. Results from this study highlight that the current standard approach using fixed periods to determine long term trends is not appropriate as statistical significance and direction of trends from short term records do not persist continuously over entire record and can be heavily influenced by extremes within the record. The importance of longer records in contextualising short term trends derived from fixed-periods influenced by natural annual, inter-annual and multi-decadal variability is highlighted. Due to the low signal (trend) to noise (variability) ratio, the apparent trends derived from the low flow indicators cannot be used as confident guides to inform future water resources planning and decision making on climate change. Infact, some derived trends contradict expected climate change impacts and even small changes in study design can change the outcomes to a high degree. Therefore it is important not only to evaluate the magnitude of trends derived from monitoring data but also when a trend of a certain magnitude in a given indicator will be detectable to inform decision making or what changes might be required to detect trends for a certain significance level. In this study, the influence of observed variance in the monitoring records on the expected detection times for trends with a

  9. A Normal Mode Perspective of Intrinsic Ocean-Climate Variability

    NASA Astrophysics Data System (ADS)

    Dijkstra, Henk

    2016-01-01

    Observations of the sea surface temperature field over more than a century indicate that there is pronounced variability in the climate system. Understanding the mechanisms of this variability is crucial to determine the role of variations in ocean heat content in past and future climate changes. When a steady background state in an ocean-climate model is slightly perturbed, the long-time response is determined by the spatial patterns of the normal modes. Here, the type and patterns of normal modes for a range of different equilibrium states in a hierarchy of ocean-climate models are reviewed. The rather elegant organization of these normal modes is demonstrated, and prototype physical mechanisms explaining patterns of sea surface temperature variability based on these normal modes are provided.

  10. Reservoirs performances under climate variability: a case study

    NASA Astrophysics Data System (ADS)

    Longobardi, A.; Mautone, M.; de Luca, C.

    2014-09-01

    A case study, the Piano della Rocca dam (southern Italy) is discussed here in order to quantify the system performances under climate variability conditions. Different climate scenarios have been stochastically generated according to the tendencies in precipitation and air temperature observed during recent decades for the studied area. Climate variables have then been filtered through an ARMA model to generate, at the monthly scale, time series of reservoir inflow volumes. Controlled release has been computed considering the reservoir is operated following the standard linear operating policy (SLOP) and reservoir performances have been assessed through the calculation of reliability, resilience and vulnerability indices (Hashimoto et al. 1982), comparing current and future scenarios of climate variability. The proposed approach can be suggested as a valuable tool to mitigate the effects of moderate to severe and persistent droughts periods, through the allocation of new water resources or the planning of appropriate operational rules.

  11. Quality Assurance for Essential Climate Variables

    NASA Astrophysics Data System (ADS)

    Folkert Boersma, K.; Muller, Jan-Peter

    2015-04-01

    Satellite data are of central interest to the QA4ECV project. Satellites have revolutionized the Earth's observation system of climate change and air quality over the past three decades, providing continuous data for the entire Earth. However, many users of these data are lost in the fog as to the quality of these satellite data. Because of this, the European Union expressed in its 2013 FP7 Space Research Call a need for reliable, traceable, and understandable quality information on satellite data records that could serve as a blueprint contribution to a future Copernicus Climate Change Service. The potential of satellite data to benefit climate change and air quality services is too great to be ignored. QA4ECV therefore bridges the gap between end-users of satellite data and the satellite data products. We are developing an internationally acceptable Quality Assurance (QA) framework that provides understandable and traceable quality information for satellite data used in climate and air quality services. Such a framework should deliver the historically linked long-term data sets that users need, in a format that they can readily use. QA4ECV has approached more than 150 users and suppliers of satellite data to collect their needs and expectations. The project will use their response as a guideline for developing user-friendly tools to obtain information on the completeness, accuracy, and fitness-for-purpose of the satellite datasets. QA4ECV collaborates with 4 joint FP7 Space projects in reaching out to scientists, policy makers, and other end-users of satellite data to improve understanding of the special challenges -and also opportunities- of working with satellite data for climate and air quality purposes. As a demonstration of its capacity, QA4ECV will generate multi-decadal climate data records for 3 atmospheric ECV precursors (nitrogen dioxide, formaldehyde, and carbon monoxide) and 3 land ECVs (albedo, leaf area index and absorbed photosynthetically active

  12. Future Warming Patterns Linked to Today’s Climate Variability

    PubMed Central

    Dai, Aiguo

    2016-01-01

    The reliability of model projections of greenhouse gas (GHG)-induced future climate change is often assessed based on models’ ability to simulate the current climate, but there has been little evidence that connects the two. In fact, this practice has been questioned because the GHG-induced future climate change may involve additional physical processes that are not important for the current climate. Here I show that the spatial patterns of the GHG-induced future warming in the 21st century is highly correlated with the patterns of the year-to-year variations of surface air temperature for today’s climate, with areas of larger variations during 1950–1979 having more GHG-induced warming in the 21st century in all climate models. Such a relationship also exists in other climate fields such as atmospheric water vapor, and it is evident in observed temperatures from 1950–2010. The results suggest that many physical processes may work similarly in producing the year-to-year climate variations in the current climate and the GHG-induced long-term changes in the 21st century in models and in the real world. They support the notion that models that simulate present-day climate variability better are likely to make more reliable predictions of future climate change. PMID:26750759

  13. Future Warming Patterns Linked to Today’s Climate Variability

    NASA Astrophysics Data System (ADS)

    Dai, Aiguo

    2016-01-01

    The reliability of model projections of greenhouse gas (GHG)-induced future climate change is often assessed based on models’ ability to simulate the current climate, but there has been little evidence that connects the two. In fact, this practice has been questioned because the GHG-induced future climate change may involve additional physical processes that are not important for the current climate. Here I show that the spatial patterns of the GHG-induced future warming in the 21st century is highly correlated with the patterns of the year-to-year variations of surface air temperature for today’s climate, with areas of larger variations during 1950-1979 having more GHG-induced warming in the 21st century in all climate models. Such a relationship also exists in other climate fields such as atmospheric water vapor, and it is evident in observed temperatures from 1950-2010. The results suggest that many physical processes may work similarly in producing the year-to-year climate variations in the current climate and the GHG-induced long-term changes in the 21st century in models and in the real world. They support the notion that models that simulate present-day climate variability better are likely to make more reliable predictions of future climate change.

  14. Future Warming Patterns Linked to Today's Climate Variability.

    PubMed

    Dai, Aiguo

    2016-01-01

    The reliability of model projections of greenhouse gas (GHG)-induced future climate change is often assessed based on models' ability to simulate the current climate, but there has been little evidence that connects the two. In fact, this practice has been questioned because the GHG-induced future climate change may involve additional physical processes that are not important for the current climate. Here I show that the spatial patterns of the GHG-induced future warming in the 21(st) century is highly correlated with the patterns of the year-to-year variations of surface air temperature for today's climate, with areas of larger variations during 1950-1979 having more GHG-induced warming in the 21(st) century in all climate models. Such a relationship also exists in other climate fields such as atmospheric water vapor, and it is evident in observed temperatures from 1950-2010. The results suggest that many physical processes may work similarly in producing the year-to-year climate variations in the current climate and the GHG-induced long-term changes in the 21(st) century in models and in the real world. They support the notion that models that simulate present-day climate variability better are likely to make more reliable predictions of future climate change. PMID:26750759

  15. Future warming patterns linked to today’s climate variability

    DOE PAGESBeta

    Dai, Aiguo

    2016-01-11

    The reliability of model projections of greenhouse gas (GHG)-induced future climate change is often assessed based on models’ ability to simulate the current climate, but there has been little evidence that connects the two. In fact, this practice has been questioned because the GHG-induced future climate change may involve additional physical processes that are not important for the current climate. Here I show that the spatial patterns of the GHG-induced future warming in the 21st century is highly correlated with the patterns of the year-to-year variations of surface air temperature for today’s climate, with areas of larger variations during 1950–1979more » having more GHG-induced warming in the 21st century in all climate models. Such a relationship also exists in other climate fields such as atmospheric water vapor, and it is evident in observed temperatures from 1950–2010. The results suggest that many physical processes may work similarly in producing the year-to-year climate variations in the current climate and the GHG-induced long-term changes in the 21st century in models and in the real world. Furthermore, they support the notion that models that simulate present-day climate variability better are likely to make more reliable predictions of future climate change.« less

  16. Ordered Short-Term Memory Differs in Signers and Speakers: Implications for Models of Short-Term Memory

    ERIC Educational Resources Information Center

    Bavelier, Daphne; Newport, Elissa L.; Hall, Matt; Supalla, Ted; Boutla, Mrim

    2008-01-01

    Capacity limits in linguistic short-term memory (STM) are typically measured with forward span tasks in which participants are asked to recall lists of words in the order presented. Using such tasks, native signers of American Sign Language (ASL) exhibit smaller spans than native speakers ([Boutla, M., Supalla, T., Newport, E. L., & Bavelier, D.…

  17. Pacific Decadal Climate Variability and Predictability

    NASA Astrophysics Data System (ADS)

    Kirtman, B.

    2006-12-01

    The current understanding of decadal variability in both the tropical and extra-tropical Pacific is presented. Modeling studies into causes of mid-latitude ocean variability often focus on to what extent the variability involves coupled ocean-atmosphere feedbacks versus the uncoupled response to atmospheric stochastic white noise forcing. The coupled feedbacks are either viewed as a generalization of the Hasselman (1976) theory to include local air-sea interactions, which could amplify the low frequency response without any preferred time scale or as involving a "delayed oscillator" due to ocean memory whereby the variability has some preferred time scale. Generally, the coupled air-sea feedbacks are stable requiring atmospheric stochastic forcing, and the inclusion of ocean dynamics is thought to enhance the variability. The uncoupled stochastic forcing of the ocean includes a number of proposed physical mechanisms for the preferred low frequency. These mechanisms include oceanic advection processes associated with the mid-latitude gyre, an atmospheric pattern of forcing with a preferred length scale or position, the dynamical adjustment of the extra-tropical ocean circulation via long baroclinic Rossby waves, and Ekman pumping. Another possibility is that tropical forcing via some atmospheric "bridge" acts as a source of North Pacific decadal variations, which may or may not be amplified by coupled feedbacks. The amplitude and frequency of ENSO exhibits variations on decadal timescales. Whether these variations are driven by low frequency variability in the tropical Pacific mean state or are just sampling issues associated with some sort of random walk process has been the subject of some debate. Accordingly, the current literature includes a number of studies proposing mechanisms for the decadal variability of the tropical Pacific, and, as a counter argument, studies examining the null hypothesis that the amplitude and frequency variations are simply related to

  18. The projected timing of climate departure from recent variability

    NASA Astrophysics Data System (ADS)

    Mora, Camilo; Frazier, Abby G.; Longman, Ryan J.; Dacks, Rachel S.; Walton, Maya M.; Tong, Eric J.; Sanchez, Joseph J.; Kaiser, Lauren R.; Stender, Yuko O.; Anderson, James M.; Ambrosino, Christine M.; Fernandez-Silva, Iria; Giuseffi, Louise M.; Giambelluca, Thomas W.

    2013-10-01

    Ecological and societal disruptions by modern climate change are critically determined by the time frame over which climates shift beyond historical analogues. Here we present a new index of the year when the projected mean climate of a given location moves to a state continuously outside the bounds of historical variability under alternative greenhouse gas emissions scenarios. Using 1860 to 2005 as the historical period, this index has a global mean of 2069 (+/-18years s.d.) for near-surface air temperature under an emissions stabilization scenario and 2047 (+/-14years s.d.) under a `business-as-usual' scenario. Unprecedented climates will occur earliest in the tropics and among low-income countries, highlighting the vulnerability of global biodiversity and the limited governmental capacity to respond to the impacts of climate change. Our findings shed light on the urgency of mitigating greenhouse gas emissions if climates potentially harmful to biodiversity and society are to be prevented.

  19. Do bioclimate variables improve performance of climate envelope models?

    USGS Publications Warehouse

    Watling, James I.; Romañach, Stephanie S.; Bucklin, David N.; Speroterra, Carolina; Brandt, Laura A.; Pearlstine, Leonard G.; Mazzotti, Frank J.

    2012-01-01

    Climate envelope models are widely used to forecast potential effects of climate change on species distributions. A key issue in climate envelope modeling is the selection of predictor variables that most directly influence species. To determine whether model performance and spatial predictions were related to the selection of predictor variables, we compared models using bioclimate variables with models constructed from monthly climate data for twelve terrestrial vertebrate species in the southeastern USA using two different algorithms (random forests or generalized linear models), and two model selection techniques (using uncorrelated predictors or a subset of user-defined biologically relevant predictor variables). There were no differences in performance between models created with bioclimate or monthly variables, but one metric of model performance was significantly greater using the random forest algorithm compared with generalized linear models. Spatial predictions between maps using bioclimate and monthly variables were very consistent using the random forest algorithm with uncorrelated predictors, whereas we observed greater variability in predictions using generalized linear models.

  20. Climate Change and Climate Variability in the Latin American Region

    NASA Astrophysics Data System (ADS)

    Magrin, G. O.; Gay Garcia, C.; Cruz Choque, D.; Gimenez-Sal, J. C.; Moreno, A. R.; Nagy, G. J.; Nobre, C.; Villamizar, A.

    2007-05-01

    Over the past three decades LA was subjected to several climate-related impacts due to increased El Niño occurrences. Two extremely intense episodes of El Niño and other increased climate extremes happened during this period contributing greatly to augment the vulnerability of human systems to natural disasters. In addition to weather and climate, the main drivers of the increased vulnerability are demographic pressure, unregulated urban growth, poverty and rural migration, low investment in infrastructure and services, and problems in inter-sector coordination. As well, increases in temperature and increases/decreases in precipitation observed during the last part of 20th century have yet led to intensification of glaciers melting, increases in floods/droughts and forest fires frequency, increases in morbidity and mortality, increases in plant diseases incidence; lost of biodiversity, reduction in dairy cattle production, and problems with hydropower generation, highly affecting LA human system. For the end of the 21st century, the projected mean warming for LA ranges from 1 to 7.5ºC and the frequency of weather and climate extremes could increase. Additionally, deforestation is projected to continue leading to a reduction of 25 percent in Amazonia forest in 2020 and 40 percent in 2050. Soybeans planted area in South America could increase by 55 percent by 2020 enhancing aridity/desertification in many of the already water- stressed regions. By 2050 LA population is likely to be 50 percent larger than in 2000, and migration from the country sides to the cities will continue. In the near future, these predicted changes are very likely to severely affect a number of ecosystems and sectors distribution; b) Disappearing most tropical glaciers; c) Reducing water availability and hydropower generation; d) Increasing desertification and aridity; e) Severely affecting people, resources and economic activities in coastal areas; f) Increasing crop's pests and diseases

  1. Taking the pulse of mountains: Ecosystem responses to climatic variability

    USGS Publications Warehouse

    Fagre, D.B.; Peterson, D.L.; Hessl, A.E.

    2003-01-01

    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

  2. Accuracy of short term Sea Ice Drift Forecasts using a coupled Ice-Ocean Model

    NASA Astrophysics Data System (ADS)

    Schweiger, A. J. B.; Zhang, J.

    2015-12-01

    Sea ice drift forecasts for the Arctic for the summer of 2014 are investigated. Sea ice forecasts are generated for 6 hours to 9 days using the Marginal Ice Zone Modelling and Assimilation System (MIZMAS) and 6 hourly forecasts of atmospheric forcing variables from the NOAA Climate Forecast System (CFSv2). Forecast sea ice drift speed is compared to observations from drifting buoys and other observation platforms. Forecast buoy positions are compared with observed positions at 24 hours to 9 days from the initial forecast. Forecast skill is assessed relative to forecasts made using an ice velocity climatology generated from multi-year integrations of the same model. RMS errors for ice speed are found in the order of 5 km/day for 24 h to 48 h using the sea ice model vs. 12 km/day using climatology. Following adjustments in the sea ice model to remove systematic biases in direction and speed, predicted buoy position RMS errors are improved from 8 km 6.5 km for 24 hour forecasts and 15 km after 72 hours. Using the forecast model increases the probability of tracking a target drifting in sea ice with a 10x10 km sized image to 95% vs. 50% using climatology. The results are generated in the context of planning and scheduling the acquisition of high resolution images which need to follow buoys or research platforms for scientific research but additional applications such as navigation in the Arctic waters may benefit from this accuracy assessment. Ideas for future improvement of short term sea ice forecasts and relevance for longer term predictions are explored.

  3. Deglacial climate variability in central Florida, USA

    USGS Publications Warehouse

    Willard, D.A.; Bernhardt, C.E.; Brooks, G.R.; Cronin, T. M.; Edgar, T.; Larson, R.

    2007-01-01

    Pollen and ostracode evidence from lacustrine sediments underlying modern Tampa Bay, Florida, document frequent and abrupt climatic and hydrological events superimposed on deglacial warming in the subtropics. Radiocarbon chronology on well-preserved mollusk shells and pollen residue from core MD02-2579 documents continuous sedimentation in a variety of non-marine habitats in a karst-controlled basin from 20 ka to 11.5 ka. During the last glacial maximum (LGM), much drier and cooler-than-modern conditions are indicated by pollen assemblages enriched in Chenopodiaceae and Carya, with rare Pinus (Pinus pollen increased to 20–40% during the warming of the initial deglaciation (∼ 17.2 ka), reaching near modern abundance (60–80%) during warmer, moister climates of the Bølling/Allerød interval (14.7–12.9 ka). Within the Bølling/Allerød, centennial-scale dry events corresponding to the Older Dryas and Intra-Allerød Cold Period indicate rapid vegetation response (

  4. Short-term synaptic plasticity and heterogeneity in neural systems

    NASA Astrophysics Data System (ADS)

    Mejias, J. F.; Kappen, H. J.; Longtin, A.; Torres, J. J.

    2013-01-01

    We review some recent results on neural dynamics and information processing which arise when considering several biophysical factors of interest, in particular, short-term synaptic plasticity and neural heterogeneity. The inclusion of short-term synaptic plasticity leads to enhanced long-term memory capacities, a higher robustness of memory to noise, and irregularity in the duration of the so-called up cortical states. On the other hand, considering some level of neural heterogeneity in neuron models allows neural systems to optimize information transmission in rate coding and temporal coding, two strategies commonly used by neurons to codify information in many brain areas. In all these studies, analytical approximations can be made to explain the underlying dynamics of these neural systems.

  5. In Their Own Words: Assessing Global Citizenship in a Short-Term Study-Abroad Program in Bangladesh

    ERIC Educational Resources Information Center

    Gambino, Giacomo; Hashim, S. Mohsin

    2016-01-01

    The article examines whether short-term study-abroad (STSA) experiences can cultivate the cultural understandings and ethical commitments entailed by a cosmopolitan civic education. We examine students' critical reflections on their participation in a two-week study-abroad program titled "Climate Change and Sustainable Development in…

  6. Cardioprotective Signature of Short-Term Caloric Restriction

    PubMed Central

    Isserlin, Ruth; Arab, Sara; Momen, Abdul; Cheng, Henry S.; Wu, Jun; Afroze, Talat; Li, Ren-Ke; Fish, Jason E.; Bader, Gary D.; Husain, Mansoor

    2015-01-01

    Objective To understand the molecular pathways underlying the cardiac preconditioning effect of short-term caloric restriction (CR). Background Lifelong CR has been suggested to reduce the incidence of cardiovascular disease through a variety of mechanisms. However, prolonged adherence to a CR life-style is difficult. Here we reveal the pathways that are modulated by short-term CR, which are associated with protection of the mouse heart from ischemia. Methods Male 10-12 wk old C57bl/6 mice were randomly assigned to an ad libitum (AL) diet with free access to regular chow, or CR, receiving 30% less food for 7 days (d), prior to myocardial infarction (MI) via permanent coronary ligation. At d8, the left ventricles (LV) of AL and CR mice were collected for Western blot, mRNA and microRNA (miR) analyses to identify cardioprotective gene expression signatures. In separate groups, infarct size, cardiac hemodynamics and protein abundance of caspase 3 was measured at d2 post-MI. Results This short-term model of CR was associated with cardio-protection, as evidenced by decreased infarct size (18.5±2.4% vs. 26.6±1.7%, N=10/group; P=0.01). mRNA and miR profiles pre-MI (N=5/group) identified genes modulated by short-term CR to be associated with circadian clock, oxidative stress, immune function, apoptosis, metabolism, angiogenesis, cytoskeleton and extracellular matrix (ECM). Western blots pre-MI revealed CR-associated increases in phosphorylated Akt and GSK3ß, reduced levels of phosphorylated AMPK and mitochondrial related proteins PGC-1α, cytochrome C and cyclooxygenase (COX) IV, with no differences in the levels of phosphorylated eNOS or MAPK (ERK1/2; p38). CR regimen was also associated with reduced protein abundance of cleaved caspase 3 in the infarcted heart and improved cardiac function. PMID:26098549

  7. 75 FR 58285 - Short-Term, Small Amount Loans

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-24

    ...NCUA is amending its general lending rule to enable Federal credit unions (FCUs) to offer short-term, small amount loans (STS loans) as a viable alternative to predatory payday loans. The amendment permits FCUs to charge a higher interest rate for an STS loan than is permitted under the general lending rule, but imposes limitations on the permissible term, amount, and fees associated with an......

  8. Short-term hydroelectric generation model. Model documentation report

    SciTech Connect

    1996-12-01

    The purpose of this report is to define the objectives of the Energy Information Administration`s (EIA) Short-Term Hydroelectric Generation Model (STHGM), describe its basic approach, and to provide details on the model structure. This report is intended as a reference document for model analysts, users, and the general public. Documentation of the model is in accordance with the EIA`s legal obligation to provide adequate documentation in support of its models.

  9. Auditory Short-Term Memory Activation during Score Reading

    PubMed Central

    Simoens, Veerle L.; Tervaniemi, Mari

    2013-01-01

    Performing music on the basis of reading a score requires reading ahead of what is being played in order to anticipate the necessary actions to produce the notes. Score reading thus not only involves the decoding of a visual score and the comparison to the auditory feedback, but also short-term storage of the musical information due to the delay of the auditory feedback during reading ahead. This study investigates the mechanisms of encoding of musical information in short-term memory during such a complicated procedure. There were three parts in this study. First, professional musicians participated in an electroencephalographic (EEG) experiment to study the slow wave potentials during a time interval of short-term memory storage in a situation that requires cross-modal translation and short-term storage of visual material to be compared with delayed auditory material, as it is the case in music score reading. This delayed visual-to-auditory matching task was compared with delayed visual-visual and auditory-auditory matching tasks in terms of EEG topography and voltage amplitudes. Second, an additional behavioural experiment was performed to determine which type of distractor would be the most interfering with the score reading-like task. Third, the self-reported strategies of the participants were also analyzed. All three parts of this study point towards the same conclusion according to which during music score reading, the musician most likely first translates the visual score into an auditory cue, probably starting around 700 or 1300 ms, ready for storage and delayed comparison with the auditory feedback. PMID:23326487

  10. Short term UV line profile variation in 59 Cyg

    NASA Technical Reports Server (NTRS)

    Grady, C. A.; Doazan, V.; Peters, G. J.; Willis, A.; Snow, T. P.; Aitken, D.; Barker, P. K.; Bolton, C. T.; Henrichs, H.; Kitchen, C. R.

    1982-01-01

    The International ultraviolet Explorer high dispersion spectra of 59 Cyg obtained as part of the long term monitoring program have shown that noticeable variation can occur in C 5 and N 5 on timescales 3 hours t24 to 28 hours. In order to begin to resolve whether these changes occur continuously or sporadically, 48 hours were devoted to monitoring this star in January 1982. The January spectra show no short term variation, which may be consistent with sporadic rather than continuous variation.

  11. An ethics curriculum for short-term global health trainees

    PubMed Central

    2013-01-01

    Background Interest in short-term global health training and service programs continues to grow, yet they can be associated with a variety of ethical issues for which trainees or others with limited global health experience may not be prepared to address. Therefore, there is a clear need for educational interventions concerning these ethical issues. Methods We developed and evaluated an introductory curriculum, “Ethical Challenges in Short-term Global Health Training.” The curriculum was developed through solicitation of actual ethical issues experienced by trainees and program leaders; content drafting; and external content review. It was then evaluated from November 1, 2011, through July 1, 2012, by analyzing web usage data and by conducting user surveys. The survey included basic demographic data; prior experience in global health and global health ethics; and assessment of cases within the curriculum. Results The ten case curriculum is freely available at http://ethicsandglobalhealth.org. An average of 238 unique visitors accessed the site each month (standard deviation, 19). Of users who had been abroad before for global health training or service, only 31% reported prior ethics training related to short-term work. Most users (62%) reported accessing the site via personal referral or their training program; however, a significant number (28%) reported finding the site via web search, and 8% discovered it via web links. Users represented different fields: medicine (46%), public health (15%), and nursing (11%) were most common. All cases in the curriculum were evaluated favorably. Conclusions The curriculum is meeting a critical need for an introduction to the ethical issues in short-term global health training. Future work will integrate this curriculum within more comprehensive curricula for global health and evaluate specific knowledge and behavioral effects, including at training sites abroad. PMID:23410089

  12. Auditory short-term memory activation during score reading.

    PubMed

    Simoens, Veerle L; Tervaniemi, Mari

    2013-01-01

    Performing music on the basis of reading a score requires reading ahead of what is being played in order to anticipate the necessary actions to produce the notes. Score reading thus not only involves the decoding of a visual score and the comparison to the auditory feedback, but also short-term storage of the musical information due to the delay of the auditory feedback during reading ahead. This study investigates the mechanisms of encoding of musical information in short-term memory during such a complicated procedure. There were three parts in this study. First, professional musicians participated in an electroencephalographic (EEG) experiment to study the slow wave potentials during a time interval of short-term memory storage in a situation that requires cross-modal translation and short-term storage of visual material to be compared with delayed auditory material, as it is the case in music score reading. This delayed visual-to-auditory matching task was compared with delayed visual-visual and auditory-auditory matching tasks in terms of EEG topography and voltage amplitudes. Second, an additional behavioural experiment was performed to determine which type of distractor would be the most interfering with the score reading-like task. Third, the self-reported strategies of the participants were also analyzed. All three parts of this study point towards the same conclusion according to which during music score reading, the musician most likely first translates the visual score into an auditory cue, probably starting around 700 or 1300 ms, ready for storage and delayed comparison with the auditory feedback. PMID:23326487

  13. Randomness and Earth’s Climate Variability

    NASA Astrophysics Data System (ADS)

    Levinshtein, Michael; Dergachev, Valentin; Dmitriev, Alexander; Shmakov, Pavel

    2016-02-01

    Paleo-Sciences including palaeoclimatology and palaeoecology have accumulated numerous records related to climatic changes. The researchers have usually tried to identify periodic and quasi-periodic processes in these paleoscientific records. In this paper, we show that this analysis is incomplete. As follows from our results, random processes, namely processes with a single-time-constant τ0 (noise with a Lorentzian noise spectrum), play a very important and, perhaps, a decisive role in numerous natural phenomena. For several of very important natural phenomena the characteristic time constants τ0 are very similar and equal to (5‑8) × 103 years. However, this value of τ0 is not universal. For example, the spectral density fluctuations of the atmospheric radiocarbon δ14C are characterized by a Lorentzian with τ0 ≈ 300 years. The frequency dependence of spectral density fluctuations for benthic δ18O records contains two Lorentzians with τ0 ≈ 8000 years and τ0 > 105 years.

  14. Short term creep rupture predictions for tantalum alloy T-111

    SciTech Connect

    Stephens, J.J. )

    1991-01-01

    A knowledge of the short term creep rupture behavior of Tantalum alloy T-111 is necessary to predict device integrity in the heat source section of Radioisotope Thermoelectric Generators (RTGs) at the end of service life, in the event of a fuel fire. High pressures exist in RTGs near the end of service life, these are caused by gas generation resulting from radioactive decay of the nuclear fuel. The internal pressure exerts a significant hoop stress on the T-111 alloy structural containment member. This paper analyses the short term creep behavior (rupture times up to {similar to}2{times}10{sup 3} hrs.) of cold worked (CW) T-111 alloy, using the existing data of Stephenson (1967). Corellations for the time to rupture, time to 1% strain and minimum creep rate have been obtained from this data using multivariable linear regression analysis. These results are compared to other short term rupture data for T-111 alloy. Finally, at the stress/temperature levels relevant to the RTG fuel fire scenario near the end of service life, the rupture time correlation for T-111 alloy predicts a rupture time of approximately 100 hrs.

  15. Short term creep rupture predictions for Tantalum alloy T-3

    SciTech Connect

    Stephens, J.J.

    1991-01-01

    A knowledge of the short term creep rupture behavior of Tantalum alloy T-111 is necessary to predict device integrity in the heat source section of Radioisotope Thermoelectric Generators (RTG's) at the end of service life, in the event of a fuel fire. High pressures exist in RTG's near the end of service life, these are caused by gas generation resulting from radioactive decay of the nuclear fuel. The internal pressure exerts a significant hoop stress on the T-111 alloy structural containment member. This paper analyses the short term creep behavior (rupture times up to {approximately}2 {times} 10{sup 3} hrs.) of cold worked (CW) T-111 alloy, using the existing data of Stephenson (1967). Corellations for the time to rupture, time to 1% strain and minimum creep rate have been obtained from this data using multivariable linear regression analysis. These results are compared to other short term rupture data for T-111 alloy. Finally, at the stress/temperature levels relevant to the RTG fuel fire scenario near the end of service life, the rupture time correlation for T-111 alloy predicts a rupture time of approximately 100 hrs. 10 refs., 3 figs., 1 tab.

  16. Does tonality boost short-term memory in congenital amusia?

    PubMed

    Albouy, Philippe; Schulze, Katrin; Caclin, Anne; Tillmann, Barbara

    2013-11-01

    Congenital amusia is a neuro-developmental disorder of music perception and production. Recent findings have demonstrated that this deficit is linked to an impaired short-term memory for tone sequences. As it has been shown before that non-musicians' implicit knowledge of musical regularities can improve short-term memory for tone information, the present study investigated if this type of implicit knowledge could also influence amusics' short-term memory performance. Congenital amusics and their matched controls, who were non-musicians, had to indicate whether sequences of five tones, presented in pairs, were the same or different; half of the pairs respected musical regularities (tonal sequences) and the other half did not (atonal sequences). As previously reported for non-musician participants, the control participants showed better performance (as measured with d') for tonal sequences than for atonal ones. While this improvement was not observed in amusics, both control and amusic participants showed faster response times for tonal sequences than for atonal sequences. These findings suggest that some implicit processing of tonal structures is potentially preserved in congenital amusia. This observation is encouraging as it strengthens the perspective to exploit implicit knowledge to help reducing pitch perception and memory deficits in amusia. PMID:24041778

  17. An approach to distribution short-term load forecasting

    SciTech Connect

    Stratton, R.C.; Gaustad, K.L.

    1995-03-01

    This paper reports on the developments and findings of the Distribution Short-Term Load Forecaster (DSTLF) research activity. The objective of this research is to develop a distribution short-term load forecasting technology consisting of a forecasting method, development methodology, theories necessary to support required technical components, and the hardware and software tools required to perform the forecast The DSTLF consists of four major components: monitored endpoint load forecaster (MELF), nonmonitored endpoint load forecaster (NELF), topological integration forecaster (TIF), and a dynamic tuner. These components interact to provide short-term forecasts at various points in the, distribution system, eg., feeder, line section, and endpoint. This paper discusses the DSTLF methodology and MELF component MELF, based on artificial neural network technology, predicts distribution endpoint loads for an hour, a day, and a week in advance. Predictions are developed using time, calendar, historical load, and weather data. The overall DSTLF architecture and a prototype MELF module for retail endpoints have been developed. Future work will be focused on refining and extending MELF and developing NELF and TIF capabilities.

  18. Frequency-specific insight into short-term memory capacity.

    PubMed

    Feurra, Matteo; Galli, Giulia; Pavone, Enea Francesco; Rossi, Alessandro; Rossi, Simone

    2016-07-01

    The digit span is one of the most widely used memory tests in clinical and experimental neuropsychology for reliably measuring short-term memory capacity. In the forward version, sequences of digits of increasing length have to be reproduced in the order in which they are presented, whereas in the backward version items must be reproduced in the reversed order. Here, we assessed whether transcranial alternating current stimulation (tACS) increases the memory span for digits of young and midlife adults. Imperceptibly weak electrical currents in the alpha (10 Hz), beta (20 Hz), theta (5 Hz), and gamma (40 Hz) range, as well as a sham stimulation, were delivered over the left posterior parietal cortex, a cortical region thought to sustain maintenance processes in short-term memory through oscillatory brain activity in the beta range. We showed a frequency-specific effect of beta-tACS that robustly increased the forward memory span of young, but not middle-aged, healthy individuals. The effect correlated with age: the younger the subjects, the greater the benefit arising from parietal beta stimulation. Our results provide evidence of a short-term memory capacity improvement in young adults by online frequency-specific tACS application. PMID:27121583

  19. 2-arachidonoylglycerol signaling impairs short-term fear extinction

    PubMed Central

    Hartley, N D; Gunduz-Cinar, O; Halladay, L; Bukalo, O; Holmes, A; Patel, S

    2016-01-01

    Impairments in fear extinction are thought to be central to the psychopathology of posttraumatic stress disorder, and endocannabinoid (eCB) signaling has been strongly implicated in extinction learning. Here we utilized the monoacylglycerol lipase inhibitor JZL184 to selectively augment brain 2-AG levels combined with an auditory cue fear-conditioning paradigm to test the hypothesis that 2-AG-mediated eCB signaling modulates short-term fear extinction learning in mice. We show that systemic JZL184 impairs short-term extinction learning in a CB1 receptor-dependent manner without affecting non-specific freezing behavior or the acquisition of conditioned fear. This effect was also observed in over-conditioned mice environmentally manipulated to re-acquire fear extinction. Cumulatively, the effects of JZL184 appear to be partly due to augmentation of 2-AG signaling in the basolateral nucleus of the amygdala (BLA), as direct microinfusion of JZL184 into the BLA produced similar results. Moreover, we elucidate a short ~3-day temporal window during which 2-AG augmentation impairs extinction behavior, suggesting a preferential role for 2-AG-mediated eCB signaling in the modulation of short-term behavioral sequelae to acute traumatic stress exposure. PMID:26926885

  20. Short-Term Effect of Coarse Particles on Daily Mortality Rate in A Tropical City, Kaohsiung, Taiwan.

    PubMed

    Tsai, Shang-Shyue; Weng, Yi-Hao; Chiu, Ya-Wen; Yang, Chun-Yuh

    2015-01-01

    Many studies examined the short-term effects of air pollution on frequency of daily mortality over the past two decades. However, information on the relationship between exposure to levels of coarse particles (PM(2.5-10)) and daily mortality rate is relatively sparse due to limited availability of monitoring data and findings are inconsistent. This study was undertaken to determine whether an association exists between PM(2.5-10) levels and rate of daily mortality in Kaohsiung, Taiwan, a large industrial city with a tropical climate. Daily mortality rate, air pollution parameters, and weather data for Kaohsiung were obtained for the period 2006-2008. The relative risk (RR) of daily mortality occurrence was estimated using a time-stratified case-crossover approach, controlling for (1) weather variables, (2) day of the week, (3) seasonality, and (4) long-term time trends. For the single-pollutant model without adjustment for other pollutants, PM(2.5-10) exposure levels showed significant correlation with total mortality rate both on warm and cool days, with an interquartile range increase associated with a 14% (95% CI = 5-23%) and 12% (95% CI = 5-20%) rise in number of total deaths, respectively. In two-pollutant models, PM(2.5-10) exerted significant influence on total mortality frequency after inclusion of sulfur dioxide (SO(2)) on warm days. On cool days, PM(2.5-10) induced significant elevation in total mortality rate when SO(2) or ozone (O(3)) was added in the regression model. There was no apparent indication of an association between PM(2.5-10) exposure and deaths attributed to respiratory and circulatory diseases. This study provided evidence of correlation between short-term exposure to PM(2.5-10) and increased risk of death for all causes. PMID:26580668

  1. Responses of Emergent Behaviour in Headwater Catchments to Long-term and Short-term Environmental Change

    NASA Astrophysics Data System (ADS)

    Tetzlaff, D.; Soulsby, C.; Malcolm, I. A.; Brewer, M. J.

    2007-12-01

    Emergent behaviour of hydrological processes at the catchment scale often results in relatively simple and predictable functional characteristics which are underpinned by heterogeneous, complex processes at the small scale. It is unclear how such small-scale processes are affected by long- and short-term perturbations in forcing factors affected by various environmental changes. This leads to uncertainty in how emergent behaviour will change and how hydrology and hydrochemistry will respond at the catchment scale. A powerful resource in improving predictions of such responses is applying advanced statistical analysis to long-term data sets of conservative tracers, particularly in gauged catchments that are subject to marked environmental change. Changes in tracer behaviour can provide an integrated insight into the emergent response of system functioning and its non-linear characteristics. In this paper, we present the analysis of long-term tracer data collected since 1982 in 2 small (ca. 1km2) experimental catchments in the Scottish highlands. These have been affected by marked change and variability in driving variables of climate, land cover and rainfall chemistry: Annual rainfall ranged between 1490 and 2500mm and an average 1°C increase in air temperatures was observed over the monitoring period. In addition, forestry operations resulted in 70% of each catchment being clear felled. Finally, air pollution legislation targeting acid emissions has improved the quality of precipitation, resulting in a marked reduction in acid deposition. Long-term (20 year, weekly) time-series analyses of two tracers are used to assess changes in emergent catchment behaviour. Chloride input-output time series are analysed using a range of residence time models which highlighted non-stationarity in the catchment mean residence times (which ranged between 2-11 months for individual years) and corresponding residence time distributions. At the catchments scale these were driven

  2. Terrestrial essential climate variables (ECVs) at a glance

    USGS Publications Warehouse

    Stitt, Susan; Dwyer, John; Dye, Dennis; Josberger, Edward

    2011-01-01

    The Global Terrestrial Observing System, Global Climate Observing System, World Meteorological Organization, and Committee on Earth Observation Satellites all support consistent global land observations and measurements. To accomplish this goal, the Global Terrestrial Observing System defined 'essential climate variables' as measurements of atmosphere, oceans, and land that are technically and economically feasible for systematic observation and that are needed to meet the United Nations Framework Convention on Climate Change and requirements of the Intergovernmental Panel on Climate Change. The following are the climate variables defined by the Global Terrestrial Observing System that relate to terrestrial measurements. Several of them are currently measured most appropriately by in-place observations, whereas others are suitable for measurement by remote sensing technologies. The U.S. Geological Survey is the steward of the Landsat archive, satellite imagery collected from 1972 to the present, that provides a potential basis for deriving long-term, global-scale, accurate, timely and consistent measurements of many of these essential climate variables.

  3. Earth System Science Education Centered on Natural Climate Variability

    NASA Astrophysics Data System (ADS)

    Ramirez, P. C.; Ladochy, S.; Patzert, W. C.; Willis, J. K.

    2009-12-01

    Several new courses and many educational activities related to climate change are available to teachers and students of all grade levels. However, not all new discoveries in climate research have reached the science education community. In particular, effective learning tools explaining natural climate change are scarce. For example, the Pacific Decadal Oscillation (PDO) is a main cause of natural climate variability spanning decades. While most educators are familiar with the shorter-temporal events impacting climate, El Niño and La Niña, very little has trickled into the climate change curriculum on the PDO. We have developed two online educational modules, using an Earth system science approach, on the PDO and its role in climate change and variability. The first concentrates on the discovery of the PDO through records of salmon catch in the Pacific Northwest and Alaska. We present the connection between salmon abundance in the North Pacific to changing sea surface temperature patterns associated with the PDO. The connection between sea surface temperatures and salmon abundance led to the discovery of the PDO. Our activity also lets students explore the role of salmon in the economy and culture of the Pacific Northwest and Alaska and the environmental requirements for salmon survival. The second module is based on the climate of southern California and how changes in the Pacific Ocean , such as the PDO and ENSO (El Niño-Southern Oscillation), influence regional climate variability. PDO and ENSO signals are evident in the long-term temperature and precipitation record of southern California. Students are guided in the module to discover the relationships between Pacific Ocean conditions and southern California climate variability. The module also provides information establishing the relationship between climate change and variability and the state's water, energy, agriculture, wildfires and forestry, air quality and health issues. Both modules will be

  4. Decadal climate variability in the eastern Caribbean

    NASA Astrophysics Data System (ADS)

    Jury, Mark R.; Gouirand, Isabelle

    2011-11-01

    Rainfall variability in the eastern Caribbean during the 20th century is analyzed using principal component analysis and singular value decomposition. In contrast to earlier studies that used seasonal data, here we employ continuous signal processing. The leading mode is a decadal oscillation related to third and fourth modes of sea level pressure (SLP) and sea surface temperatures (SST) which together identify three zones of action in the Atlantic: 35°N-20°N, 20°N-5°N, and 5°N-20°S. The ability of the ECHAM4.5 model to simulate this signal is investigated. Its decadal variability is also represented through lower-order SLP and SST modes that comprise an Atlantic tripole pattern with lower pressure east of the Caribbean. Composite analysis of high and low phases of the decadal mode reflects a cool east Pacific and a more active Atlantic Intertropical Convergence Zone during boreal summer, conditions that favor the intensification of African easterly waves. The decadal signal has strengthened since 1970, yet the three centers of action in Atlantic SST are relatively unsynchronized.

  5. Quantifying the sources of uncertainty in upper air climate variables

    NASA Astrophysics Data System (ADS)

    Eghdamirad, Sajjad; Johnson, Fiona; Woldemeskel, Fitsum; Sharma, Ashish

    2016-04-01

    Future estimates of precipitation and streamflow are of utmost interest in hydrological climate change impact assessments. Just as important as the estimate itself, is the variance around the ensemble mean of the projections, this variance being defined as uncertainty in the context of this study. This uncertainty in the hydrological variables of interest is affected by uncertainty in upper air climate variables which are used in statistical downscaling of precipitation or streamflow. Here the extent of uncertainty in upper air climate variables has been assessed for a selection of commonly used atmospheric variables for downscaling, namely, geopotential height and its difference in the north-south direction, specific humidity, and eastward and northward wind speeds. Generally, in statistical downscaling, no consideration is usually given to the uncertainty of different individual variables, which can result in biases in future climate simulations. The approach of quantifying uncertainty presented here has the potential to enable modelers to better formulate downscaling approaches, leading to more accurate characterization of future precipitation and its associated uncertainty. Based on the spread of multiple-model outputs, an uncertainty measure called square root of error variance has been used to quantify the contribution of different sources of uncertainty (i.e., models, scenarios, and ensembles) in monthly future climate projections in the 21st century at the 500 hPa and 850 hPa pressure levels. It has been shown that the different climate variables and levels of the atmosphere have distinct patterns in terms of their total future uncertainty and the contributions from the three sources. Scenario and model uncertainties in general contribute reasonably evenly to total uncertainty, with smaller contributions from the initial condition ensembles.

  6. Vegetation Interaction Enhances Interdecadal Climate Variability in the Sahel

    NASA Technical Reports Server (NTRS)

    Zeng, Ning; Neelin, J. David; Lau, William K.-M.

    1999-01-01

    The role of naturally varying vegetation in influencing the climate variability in the Sahel is explored in a coupled atmosphere-land-vegetation model. The Sahel rainfall variability is influenced by sea surface temperature (SST) variations in the oceans. Land-surface feedback is found to increase this variability both on interannual and interdecadal time scales. Interactive vegetation enhances the interdecadal variation significantly, but can reduce year to year variability due to a phase lag introduced by the relatively slow vegetation adjustment time. Variations in vegetation accompany the changes in rainfall, in particular, the multi-decadal drying trend from the 1950s to the 80s.

  7. Northern high latitude climate variability of the last millennium

    NASA Astrophysics Data System (ADS)

    Andres, Heather J.

    This work explores the causes of northern high-latitude climate variations over the last millennium, and industrial and future periods. Attribution studies are performed on a suite of global climate simulations, and four historical reconstructions of Greenland surface temperatures and precipitation (two of which are new to this work). The simulations followed the protocols of the Palaeoclimate Modelling Intercomparison Project 3 and Coupled Model Intercomparison Project 5. At least half of the multi-decadal variability in simulated Greenland climate variations over the last millennium is reproduced by a linear, empirically-generated model including terms for volcanic emissions, solar insolation changes (including total solar irradiance and orbital components) and an index associated with latitudinal shifts in the North Atlantic jet. Empirical model parameters are obtained by regressing simulated Greenland temperatures and precipitation against time series for each of the response variables. Greenhouse gas radiative forcing changes are unimportant to simulated Greenland conditions over the last millennium, although they dominate after the mid-20th century. Most of the historical Greenland climate reconstructions are restricted to the industrial period, due to a lack of spatially-comprehensive climate records. They exhibit substantial differences in the timing, phasing and amplitudes of past climate variations, due to regional sensitivities in the source data and the reconstruction methodologies. Reconstructions indicate that Greenland temperatures did not begin to follow hemispheric greenhouse gas warming patterns until the mid-1990s. This discrepancy indicates either that the warming hiatus was associated with internal climate variability, or that the simulations are missing processes important to Greenland climate. For example, indirect effects of anthropogenic aerosols are not captured in the climate model employed here. All of the external climate forcings

  8. Experiences on climate variability education from an empirical perspective

    NASA Astrophysics Data System (ADS)

    Rodriguez-Puebla, Concepcion

    2015-04-01

    Education materials based on investigations are prepared for teaching climate matters using graphics representation, data analysis and GrADS software. An example of how climate teleconnection are included in the teaching activities would be presented. The goal is for students to learn about how climate variability and extreme events over a region are connected to large-scale atmospheric and oceanic circulation from an empirical perspective. Exercises and questions are prepared for collaborative and interactive learning considering the visualization and workshop activities included in the Moodle learning platform.

  9. Performance of climate field reconstruction methods over multiple seasons and climate variables

    NASA Astrophysics Data System (ADS)

    Dannenberg, Matthew P.; Wise, Erika K.

    2013-09-01

    Studies of climate variability require long time series of data but are limited by the absence of preindustrial instrumental records. For such studies, proxy-based climate reconstructions, such as those produced from tree-ring widths, provide the opportunity to extend climatic records into preindustrial periods. Climate field reconstruction (CFR) methods are capable of producing spatially-resolved reconstructions of climate fields. We assessed the performance of three commonly used CFR methods (canonical correlation analysis, point-by-point regression, and regularized expectation maximization) over spatially-resolved fields using multiple seasons and climate variables. Warm- and cool-season geopotential height, precipitable water, and surface temperature were tested for each method using tree-ring chronologies. Spatial patterns of reconstructive skill were found to be generally consistent across each of the methods, but the robustness of the validation metrics varied by CFR method, season, and climate variable. The most robust validation metrics were achieved with geopotential height, the October through March temporal composite, and the Regularized Expectation Maximization method. While our study is limited to assessment of skill over multidecadal (rather than multi-centennial) time scales, our findings suggest that the climate variable of interest, seasonality, and spatial domain of the target field should be considered when assessing potential CFR methods for real-world applications.

  10. ASSESSMENT OF THE POTENTIAL EFFECTS OF CLIMATE CHANGE AND CLIMATE VARIABILITY ON WEATHER-RELATED MORBIDITY

    EPA Science Inventory

    The potential effects of climate change and climate variability on weather-related morbidity are assessed. Heat-related and cold-related morbidity in children are analyzed. The impact of inclement weather on accidental injuries is evaluated. The relationship of violent crime to w...

  11. Effects of interannual climate variability on tropical tree cover

    NASA Astrophysics Data System (ADS)

    Holmgren, Milena; Hirota, Marina; van Nes, Egbert H.; Scheffer, Marten

    2013-08-01

    Climatic warming is substantially intensifying the global water cycle and is projected to increase rainfall variability. Using satellite data, we show that higher climatic variability is associated with reduced tree cover in the wet tropics globally. In contrast, interannual variability in rainfall can have neutral or even positive effects on tree cover in the dry tropics. In South America, tree cover in dry lands is higher in areas with high year-to-year variability in rainfall. This is consistent with evidence from case studies suggesting that in these areas rare wet episodes are essential for opening windows of opportunity where massive tree recruitment can overwhelm disturbance effects, allowing the establishment of extensive woodlands. In Australia, wet extremes have similar effects, but the net effect of rainfall variability is overwhelmed by negative effects of extreme dry years. In Africa, effects of rainfall variability are neutral for dry lands. It is most likely that differences in herbivore communities and fire regimes contribute to regulating tree expansion during wet extremes. Our results illustrate that increasing climatic variability may affect ecosystem services in contrasting, and sometimes surprising, ways. Expansion of dry tropical tree cover during extreme wet events may decrease grassland productivity but enhance carbon sequestration, soil nutrient retention and biodiversity.

  12. Short-Term Energy Outlook Supplement: Key drivers for EIA's short-term U.S. crude oil production outlook

    EIA Publications

    2013-01-01

    Crude oil production increased by 790,000 barrels per day (bbl/d) between 2011 and 2012, the largest increase in annual output since the beginning of U.S. commercial crude oil production in 1859. The U.S. Energy Information Administration (EIA) expects U.S. crude oil production to continue rising over the next two years represented in the Short-Term Energy Outlook (STEO).

  13. Climate Variability and Impact at NASA's Marshal Space Flight Center

    NASA Technical Reports Server (NTRS)

    Smoot, James L.; Jedlovec, Gary; Williams, Brett

    2013-01-01

    the Center. MSFC has begun using this climate change information to adapt short-term and long-term plans for Center operations.

  14. Climate Variability and Phytoplankton in the Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Rousseaux, Cecile

    2012-01-01

    The effect of climate variability on phytoplankton communities was assessed for the tropical and sub-tropical Pacific Ocean between 1998 and 2005 using an established biogeochemical assimilation model. The phytoplankton communities exhibited wide range of responses to climate variability, from radical shifts in the Equatorial Pacific, to changes of only a couple of phytoplankton groups in the North Central Pacific, to no significant changes in the South Pacific. In the Equatorial Pacific, climate variability dominated the variability of phytoplankton. Here, nitrate, chlorophyll and all but one of the 4 phytoplankton types (diatoms, cyanobacteria and coccolithophores) were strongly correlated (p<0.01) with the Multivariate El Nino Southern Oscillation Index (MEI). In the North Central Pacific, MEI and chlorophyll were significantly (p<0.01) correlated along with two of the phytoplankton groups (chlorophytes and coccolithophores). Ocean biology in the South Pacific was not significantly correlated with MEI. During La Nina events, diatoms increased and expanded westward along the cold tongue (correlation with MEI, r=-0.81), while cyanobacteria concentrations decreased significantly (r=0.78). El Nino produced the reverse pattern, with cyanobacteria populations increasing while diatoms plummeted. The diverse response of phytoplankton in the different major basins of the Pacific suggests the different roles climate variability can play in ocean biology.

  15. Floods, landslides and short-term meandering bedrock river dynamics

    NASA Astrophysics Data System (ADS)

    Lague, D.; Bonnet, S.; Davies, T. R.; Davy, P.

    2012-12-01

    Actively incising bedrock meanders are an ubiquitous feature of mountain belts, but the mechanisms leading to their formation and evolution are still poorly understood. As for straight bedrock rivers, we expect the combination of stochastic discharge, sediment supply and river transport capacity to play a key role in the partitioning between vertical and lateral incision. But the sinuous planform geometry yields localized high rates of outer bank incision driving localized hillslope mass wasting processes. The resulting deposits may alter patterns of sedimentation and incision leading to a strongly coupled channel-hillslope system. We aim at better understanding this coupling following two approaches : a detailed quantification of channel response to individual floods and mass-wasting events using Terrestrial Laser Scanner surveys and recent historical data; and the integration of this short-term dynamics at longer-timescales through numerical modelling. In particular, we note that many of these rivers exhibits numerous strath terraces abandoned in their inner bend documenting an evolution which is not purely continuous but rather punctuated by rapid changes in the balance between vertical and lateral erosion. Whether these changes can be tied to specific extreme events (floods, landslides, major earthquakes...) or an intrinsic instability is a key question to better understand bedrock meandering dynamics. It also has potentially important implications for the reconstruction of paleo-extremes from dated terraces or for the management of infrastructures located near actively migrating meandering bedrock rivers. This presentation focuses on the use of Terrestrial Laser Scanner to investigate the spatio-temporal patterns of bank erosion in the Rangitikei river (New-Zealand) over 3 years. The Rangitikei river is incising weakly consolidated mudstone at an average rate of 5 mm/yr since 15 kyr and has developed a very sinuous meandering pattern with several cut

  16. Sensitivity of global terrestrial ecosystems to climate variability.

    PubMed

    Seddon, Alistair W R; Macias-Fauria, Marc; Long, Peter R; Benz, David; Willis, Kathy J

    2016-03-10

    The identification of properties that contribute to the persistence and resilience of ecosystems despite climate change constitutes a research priority of global relevance. Here we present a novel, empirical approach to assess the relative sensitivity of ecosystems to climate variability, one property of resilience that builds on theoretical modelling work recognizing that systems closer to critical thresholds respond more sensitively to external perturbations. We develop a new metric, the vegetation sensitivity index, that identifies areas sensitive to climate variability over the past 14 years. The metric uses time series data derived from the moderate-resolution imaging spectroradiometer (MODIS) enhanced vegetation index, and three climatic variables that drive vegetation productivity (air temperature, water availability and cloud cover). Underlying the analysis is an autoregressive modelling approach used to identify climate drivers of vegetation productivity on monthly timescales, in addition to regions with memory effects and reduced response rates to external forcing. We find ecologically sensitive regions with amplified responses to climate variability in the Arctic tundra, parts of the boreal forest belt, the tropical rainforest, alpine regions worldwide, steppe and prairie regions of central Asia and North and South America, the Caatinga deciduous forest in eastern South America, and eastern areas of Australia. Our study provides a quantitative methodology for assessing the relative response rate of ecosystems--be they natural or with a strong anthropogenic signature--to environmental variability, which is the first step towards addressing why some regions appear to be more sensitive than others, and what impact this has on the resilience of ecosystem service provision and human well-being. PMID:26886790

  17. Sensitivity of global terrestrial ecosystems to climate variability

    NASA Astrophysics Data System (ADS)

    Seddon, Alistair W. R.; Macias-Fauria, Marc; Long, Peter R.; Benz, David; Willis, Kathy J.

    2016-03-01

    The identification of properties that contribute to the persistence and resilience of ecosystems despite climate change constitutes a research priority of global relevance. Here we present a novel, empirical approach to assess the relative sensitivity of ecosystems to climate variability, one property of resilience that builds on theoretical modelling work recognizing that systems closer to critical thresholds respond more sensitively to external perturbations. We develop a new metric, the vegetation sensitivity index, that identifies areas sensitive to climate variability over the past 14 years. The metric uses time series data derived from the moderate-resolution imaging spectroradiometer (MODIS) enhanced vegetation index, and three climatic variables that drive vegetation productivity (air temperature, water availability and cloud cover). Underlying the analysis is an autoregressive modelling approach used to identify climate drivers of vegetation productivity on monthly timescales, in addition to regions with memory effects and reduced response rates to external forcing. We find ecologically sensitive regions with amplified responses to climate variability in the Arctic tundra, parts of the boreal forest belt, the tropical rainforest, alpine regions worldwide, steppe and prairie regions of central Asia and North and South America, the Caatinga deciduous forest in eastern South America, and eastern areas of Australia. Our study provides a quantitative methodology for assessing the relative response rate of ecosystems—be they natural or with a strong anthropogenic signature—to environmental variability, which is the first step towards addressing why some regions appear to be more sensitive than others, and what impact this has on the resilience of ecosystem service provision and human well-being.

  18. Ramp Forecasting Performance from Improved Short-Term Wind Power Forecasting: Preprint

    SciTech Connect

    Zhang, J.; Florita, A.; Hodge, B. M.; Freedman, J.

    2014-05-01

    The variable and uncertain nature of wind generation presents a new concern to power system operators. One of the biggest concerns associated with integrating a large amount of wind power into the grid is the ability to handle large ramps in wind power output. Large ramps can significantly influence system economics and reliability, on which power system operators place primary emphasis. The Wind Forecasting Improvement Project (WFIP) was performed to improve wind power forecasts and determine the value of these improvements to grid operators. This paper evaluates the performance of improved short-term wind power ramp forecasting. The study is performed for the Electric Reliability Council of Texas (ERCOT) by comparing the experimental WFIP forecast to the current short-term wind power forecast (STWPF). Four types of significant wind power ramps are employed in the study; these are based on the power change magnitude, direction, and duration. The swinging door algorithm is adopted to extract ramp events from actual and forecasted wind power time series. The results show that the experimental short-term wind power forecasts improve the accuracy of the wind power ramp forecasting, especially during the summer.

  19. Estimation of desmosponge (Porifera, Demospongiae) larval settlement rates from short-term recruitment rates: Preliminary experiments

    NASA Astrophysics Data System (ADS)

    Zea, Sven

    1992-09-01

    During a study of the spatial and temporal patterns of desmosponge (Porifera, Demospongiae) recruitment on rocky and coral reef habitats of Santa Marta, Colombian Caribbean Sea, preliminary attempts were made to estimate actual settlement rates from short-term (1 to a few days) recruitment censuses. Short-term recruitment rates on black, acrylic plastic plates attached to open, non-cryptic substratum by anchor screws were low and variable (0 5 recruits/plate in 1 2 days, sets of n=5 10 plates), but reflected the depth and seasonal trends found using mid-term (1 to a few months) censusing intervals. Moreover, mortality of recruits during 1 2 day intervals was low (0 12%). Thus, short-term censusing intervals can be used to estimate actual settlement rates. To be able to make statistical comparisons, however, it is necessary to increase the number of recruits per census by pooling data of n plates per set, and to have more than one set per site or treatment.

  20. The loss of short-term visual representations over time: decay or temporal distinctiveness?

    PubMed

    Mercer, Tom

    2014-12-01

    There has been much recent interest in the loss of visual short-term memories over the passage of time. According to decay theory, visual representations are gradually forgotten as time passes, reflecting a slow and steady distortion of the memory trace. However, this is controversial and decay effects can be explained in other ways. The present experiment aimed to reexamine the maintenance and loss of visual information over the short term. Decay and temporal distinctiveness models were tested using a delayed discrimination task, in which participants compared complex and novel objects over unfilled retention intervals of variable length. Experiment 1 found no significant change in the accuracy of visual memory from 2 to 6 s, but the gap separating trials reliably influenced task performance. Experiment 2 found evidence for information loss at a 10-s retention interval, but temporally separating trials restored the fidelity of visual memory, possibly because temporally isolated representations are distinct from older memory traces. In conclusion, visual representations lose accuracy at some point after 6 s, but only within temporally crowded contexts. These findings highlight the importance of temporal distinctiveness within visual short-term memory. PMID:25314045

  1. Linking Genetic Counseling Content to Short-Term Outcomes in Individuals at Elevated Breast Cancer Risk

    PubMed Central

    Ellington, Lee; Schoenberg, Nancy; Agarwal, Parul; Jackson, Thomas; Dickinson, Stephanie; Abraham, Jame; Paskett, Electra D.; Leventhal, Howard; Andrykowski, Michael

    2014-01-01

    Few studies have linked actual genetic counseling content to short-term outcomes. Using the Self-regulation Model, the impact of cognitive and affective content in genetic counseling on short-term outcomes was studied in individuals at elevated risk of familial breast-ovarian cancer. Surveys assessed dependent variables: distress, perceived risk, and 6 knowledge measures (Meaning of Positive Test; Meaning of Negative Test; Personal Behavior; Practitioner Knowledge; Mechanisms of Cancer Inheritance; Frequency of Inherited Cancer) measured at pre- and post-counseling. Proportion of participant cognitive and affective and counselor cognitive and affective content during sessions (using LIWC software) were predictors in regressions. Knowledge increased for 5 measures and decreased for Personal Behavior, Distress and Perceived Risk. Controlling for age and education, results were significant/marginally significant for three measures. More counselor content was associated with decreases in knowledge of Personal Behavior. More participant and less counselor affective content was associated with gains in Practitioner Knowledge. More counselor cognitive, and interaction of counselor cognitive and affective content, were associated with higher perceived risk. Genetic counselors dominate the content of counseling sessions. Therefore, their content is tied more closely to short term outcomes than participant content. A lack of patient communication in sessions may pose problems for understanding of complex concepts. PMID:24671341

  2. Climatic Variability Leads to Later Seasonal Flowering of Floridian Plants

    PubMed Central

    Von Holle, Betsy; Wei, Yun; Nickerson, David

    2010-01-01

    Understanding species responses to global change will help predict shifts in species distributions as well as aid in conservation. Changes in the timing of seasonal activities of organisms over time may be the most responsive and easily observable indicator of environmental changes associated with global climate change. It is unknown how global climate change will affect species distributions and developmental events in subtropical ecosystems or if climate change will differentially favor nonnative species. Contrary to previously observed trends for earlier flowering onset of plant species with increasing spring temperatures from mid and higher latitudes, we document a trend for delayed seasonal flowering among plants in Florida. Additionally, there were few differences in reproductive responses by native and nonnative species to climatic changes. We argue that plants in Florida have different reproductive cues than those from more northern climates. With global change, minimum temperatures have become more variable within the temperate-subtropical zone that occurs across the peninsula and this variation is strongly associated with delayed flowering among Florida plants. Our data suggest that climate change varies by region and season and is not a simple case of species responding to consistently increasing temperatures across the region. Research on climate change impacts need to be extended outside of the heavily studied higher latitudes to include subtropical and tropical systems in order to properly understand the complexity of regional and seasonal differences of climate change on species responses. PMID:20657765

  3. Large-scale climate variability and its effects on mean temperature and flowering time of Prunus and Betula in Denmark

    NASA Astrophysics Data System (ADS)

    Gormsen, A. K.; Hense, A.; Toldam-Andersen, T. B.; Braun, P.

    2005-08-01

    Large-scale climate variability largely affects average climatic conditions and therefore is likely to influence the phenology of plants. In NW-Europe, the North Atlantic Oscillation (NAO) particularly influences winter climate and, through climate interactions on plants, flowering time of all tree species. In Denmark, like in many other NW-European countries, flowering of most tree species has become earlier since the end of the 1980’s. To quantify a possible relation between NAO and flowering time of tree species, two sources of phenological information from the Copenhagen area (Denmark) were analysed, i.e. pollen counts of the genus Betula and observed first bloom dates of Prunus avium. The Winter NAO explained 29 and 37% of the variation of monthly mean temperature for February and March, respectively. The influence of temperature on flowering time was up to 56% to 60% for the February April mean. A direct correlation of Winter NAO-index and flowering time also revealed a clear relation but the time of influence was earlier (December to February). This was shown to be the likely result of a combination of direct and time-lagged effects of the NAO on air and sea surface temperature. The NAO signal is apparently stored in the North Sea and then influences temperature east up to the Baltic States. It is shown that Denmark is right in the centre of direct and time-lagged effects of the NAO. This offers the possibility of using the NAO-index for predicting flowering time of Prunus avium. The beginning of pollen flow appears to be influenced too much by short-term perturbations of the climate system decreasing the value of the NAO-index for prediction. However, it indicates a close relationship between natural climate variability, measured by the NAO index, and flowering time of tree species for Denmark.

  4. Short-Term Heart Rate Variability—Influence of Gender and Age in Healthy Subjects

    PubMed Central

    Voss, Andreas; Schroeder, Rico; Heitmann, Andreas; Peters, Annette; Perz, Siegfried

    2015-01-01

    In the recent years, short-term heart rate variability (HRV) describing complex variations of beat-to-beat interval series that are mainly controlled by the autonomic nervous system (ANS) has been increasingly analyzed to assess the ANS activity in different diseases and under various conditions. In contrast to long-term HRV analysis, short-term investigations (<30 min) provide a test result almost immediately. Thus, short-term HRV analysis is suitable for ambulatory care, patient monitoring and all those applications where the result is urgently needed. In a previous study, we could show significant variations of 5-min HRV indices according to age in almost all domains (linear and nonlinear) in 1906 healthy subjects from the KORA S4 cohort. Based on the same group of subjects, general gender-related influences on HRV indices are to be determined in this study. Short-term 5-min HRV indices from linear time and frequency domain and from nonlinear methods (compression entropy, detrended fluctuation analysis, traditional and segmented Poincaré plot analysis, irreversibility analysis, symbolic dynamics, correlation and mutual information analysis) were determined from 782 females and 1124 males. First, we examined the gender differences in two age clusters (25–49 years and 50–74 years). Secondly, we investigated the gender-specific development of HRV indices in five age decade categories, namely for ages 25–34, 35–44, 45–54, 55–64 and 65–74 years. In this study, significant modifications of the indices according to gender could be obtained, especially in the frequency domain and correlation analyses. Furthermore, there were significant modifications according to age in nearly all of the domains. The gender differences disappeared within the last two age decades and the age dependencies disappeared in the last decade. To summarize gender and age influences need to be considered when performing HRV studies even if these influences only partly differ. PMID

  5. Neurocognition, psychopathology, and subjective disturbances in schizophrenia: a comparison between short-term and remitted patients.

    PubMed

    Comparelli, Anna; De Carolis, Antonella; Corigliano, Valentina; Romano, Silvia; Kotzalidis, Giorgio; Brugnoli, Roberto; Tamorri, Stefano; Curto, Martina; Tatarelli, Roberto; Ferracuti, Stefano; Girardi, Paolo

    2012-10-01

    Patients with schizophrenia present deficits in multiple domains of cognition. The study of the relationship between cognitive performance and symptoms of schizophrenia has yielded heterogeneous results. The purposes of this study were to examine the extent of the relationship between psychopathologic symptoms, cognitive function, and subjective disturbances in a group of patients affected by schizophrenia spectrum disorders and to compare short-term with remitted patients. Seventy-nine patients meeting Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria for schizophrenia, schizophreniform disorder, and schizoaffective disorder were assessed through the Positive and Negative Syndrome Scale, the Frankfurt Complaint Questionnaire, and a neuropsychologic battery exploring the 7 Measurement and Treatment Research to improve Cognition in Schizophrenia cognitive domains (speed of processing, attention/vigilance, working memory, verbal learning, visual learning, reasoning and problem solving, and social cognition) plus executive control. Neuropsychologic and psychopathologic variables were compared and correlated. Treatment groups did not differ in neuropsychologic and psychopathologic measures. The cognitive factor of the Positive and Negative Syndrome Scale correlated with worse performance on cognitive tasks and with higher scores on the Frankfurt Complaint Questionnaire 24 in the short-term, remitted, and combined groups. Subjective disturbances correlated with impaired executive control, reasoning and problem solving, and social cognition but not during the short-term phase. Both "objective" and subjective psychopathology are intertwined with cognitive function, suggesting some common underlying neural bases. The condition of being in a short-term or a remitted phase of the illness influences this interrelationship, regardless of the type of antipsychotic medication taken. PMID:22444951

  6. Short-term energy outlook. Quarterly projections, 2nd quarter 1994

    SciTech Connect

    Not Available

    1994-05-01

    The Energy Information Administration (EIA) prepares quarterly, short-term energy supply, demand, and price projections for publication in February, May, August, and November in the Short-Term Energy Outlook (Outlook). An annual supplement analyzes the performance of previous forecasts, compares recent cases with those of other forecasting services, and discusses current topics related to the short-term energy markets. The forecast period for this issue of the Outlook extends from the second quarter of 1994 through the fourth quarter of 1995. Values for the first quarter of 1994, however, are preliminary EIA estimates (for example, some monthly values for petroleum supply and disposition are derived in part from weekly data reported in the Weekly Petroleum Status Report) or are calculated from model simulations using the latest exogenous information available. The historical energy data, compiled into the second quarter 1994 version of the Short-Term Integrated Forecasting System (STIFS) database, are mostly EIA data regularly published in the Monthly Energy Review, Petroleum Supply Monthly, and other EIA publications. Minor discrepancies between the data in these publications and the historical data in this Outlook are due to independent rounding. The STIFS database is archived quarterly and is available from the National Technical Information Service. The cases are produced using the STIFS. The STIFS model is driven principally by three sets of assumptions or inputs: estimates of key macroeconomic variables, world oil price assumptions, and assumptions about the severity of weather. Macroeconomic estimates are produced by DRI/McGraw-Hill but are adjusted by EIA to reflect EIA assumptions about the world price of crude oil, energy product prices, and other assumptions which may affect the macroeconomic outlook. The EIA model is available on computer tape from the National Technical Information Service.

  7. Short-Term Synaptic Plasticity at Interneuronal Synapses Could Sculpt Rhythmic Motor Patterns.

    PubMed

    Jia, Yan; Parker, David

    2016-01-01

    The output of a neuronal network depends on the organization and functional properties of its component cells and synapses. While the characterization of synaptic properties has lagged cellular analyses, a potentially important aspect in rhythmically active networks is how network synapses affect, and are in turn affected by, network activity. This could lead to a potential circular interaction where short-term activity-dependent synaptic plasticity is both influenced by and influences the network output. The analysis of synaptic plasticity in the lamprey locomotor network was extended here to characterize the short-term plasticity of connections between network interneurons and to try and address its potential network role. Paired recordings from identified interneurons in quiescent networks showed synapse-specific synaptic properties and plasticity that supported the presence of two hemisegmental groups that could influence bursting: depression in an excitatory interneuron group, and facilitation in an inhibitory feedback circuit. The influence of activity-dependent synaptic plasticity on network activity was investigated experimentally by changing Ringer Ca(2+) levels, and in a simple computer model. A potential caveat of the experimental analyses was that changes in Ringer Ca(2+) (and compensatory adjustments in Mg(2+) in some cases) could alter several other cellular and synaptic properties. Several of these properties were tested, and while there was some variability, these were not usually significantly affected by the Ringer changes. The experimental analyses suggested that depression of excitatory inputs had the strongest influence on the patterning of network activity. The simulation supported a role for this effect, and also suggested that the inhibitory facilitating group could modulate the influence of the excitatory synaptic depression. Short-term activity-dependent synaptic plasticity has not generally been considered in spinal cord models. These

  8. Post larval, short-term, colonization patterns: The effect of substratum complexity across subtidal, adjacent, habitats

    NASA Astrophysics Data System (ADS)

    García-Sanz, Sara; Tuya, Fernando; Navarro, Pablo G.; Angulo-Preckler, Carlos; Haroun, Ricardo J.

    2012-10-01

    Benthic habitats are colonized by organisms from the water column and adjacent habitats. There are, however, variations in the 'acceptability' of any habitat to potential colonists. We assessed whether the structural complexity of artificial substrata affected patterns of short-term colonization of post larval faunal assemblages across subtidal habitats within a coastal landscape. Specifically, we tested whether short-term colonization patterns on 3 types of artificial substrata encompassing a range of complexities, including a leaf-like unit, a cushion-shaped leaf-like unit and a cushion-shaped unit, were consistent across 4 adjacent habitats: macroalgal-dominated bottoms, urchin-grazed barrens, seagrass meadows and sandy patches, at Gran Canaria (eastern Atlantic). A total of 16,174 organisms were collected after 4 weeks and 4 taxonomic groups (Crustacea, Chordata, Echinodermata and Mollusca) dominated the assemblage. Despite considerable among-taxa variability being observed in response to habitat effects, the total abundance of colonizers, as well as the abundance of Arthropoda, Chordata and Echinodermata, was affected by the habitat where collectors were deployed, but did not differ among types of collectors. Similarly, the assemblage structure of colonizers was mainly affected by the habitat, but not by the type of collector; habitat contributed to explain most variation in the assemblage structure of the four dominant taxonomic groups (from ca. 5.44-19.23%), and obscured, in all cases, variation explained by the type of collector. As a result, the variation in short-term colonization patterns of faunal assemblages into artificial collectors was mostly affected by variation associated with habitats rather than by differences in the structural complexity of collectors. The largest abundances of colonizers, particularly Echinodermata, were found on sandy patches relative to other habitats, suggesting that the 'availability', rather than any particular attribute

  9. Remote Measurement of Short-term Post-fire Vegetation Regrowth in Sierra Nevadan Forests

    NASA Astrophysics Data System (ADS)

    Meng, R.; Dennison, P. E.; Huang, C.

    2014-12-01

    Forest ecosystems in the Sierra Nevada are greatly influenced by wildfire disturbance. A study of vegetation regrowth following fire is essential for us to better understand and evaluate the effects of disturbances on ecological processes, such as carbon and nitrogen storage, soil erosion, water quality and forest dynamics. The rate of short-term vegetation recovery, as measured by Normalized Difference Vegetation Index (NDVI), was explored following fire over multiple years (1999-2006) in Sierra Nevadan forests. The role of both temporal (e.g. variations in multiple years' precipitation) and landscape factors (e.g. altitude, slope, aspect, pre-fire and immediate post-fire vegetation status, and burn severity) were investigated in explaining the short-term vegetation regrowth following fire using remote sensing on the landscape scale. Our results indicate that spatial-temporal variability existed in the short-term post-fire vegetation regrowth. Pre-fire vegetation status, burn severity, immediate post-fire wet season precipitation and elevation were found to play important roles in short-term post-fire vegetation recovery trends. Consistent with a local forest gap model, our results also corroborate that water availability may be the limiting factor for the post-fire vegetation regrowth in the lower elevation of Sierra Nevadan forests. In the future, post-disturbance vegetation regrowth trends and related controlling environmental factors following various forest disturbances (e.g. insect outbreak and forest harvest) other than wildfire can also be studied and compared using the methodology proposed in this study.

  10. Short-Term Synaptic Plasticity at Interneuronal Synapses Could Sculpt Rhythmic Motor Patterns

    PubMed Central

    Jia, Yan; Parker, David

    2016-01-01

    The output of a neuronal network depends on the organization and functional properties of its component cells and synapses. While the characterization of synaptic properties has lagged cellular analyses, a potentially important aspect in rhythmically active networks is how network synapses affect, and are in turn affected by, network activity. This could lead to a potential circular interaction where short-term activity-dependent synaptic plasticity is both influenced by and influences the network output. The analysis of synaptic plasticity in the lamprey locomotor network was extended here to characterize the short-term plasticity of connections between network interneurons and to try and address its potential network role. Paired recordings from identified interneurons in quiescent networks showed synapse-specific synaptic properties and plasticity that supported the presence of two hemisegmental groups that could influence bursting: depression in an excitatory interneuron group, and facilitation in an inhibitory feedback circuit. The influence of activity-dependent synaptic plasticity on network activity was investigated experimentally by changing Ringer Ca2+ levels, and in a simple computer model. A potential caveat of the experimental analyses was that changes in Ringer Ca2+ (and compensatory adjustments in Mg2+ in some cases) could alter several other cellular and synaptic properties. Several of these properties were tested, and while there was some variability, these were not usually significantly affected by the Ringer changes. The experimental analyses suggested that depression of excitatory inputs had the strongest influence on the patterning of network activity. The simulation supported a role for this effect, and also suggested that the inhibitory facilitating group could modulate the influence of the excitatory synaptic depression. Short-term activity-dependent synaptic plasticity has not generally been considered in spinal cord models. These results

  11. Climate variability and predictability in Northwest Africa

    NASA Astrophysics Data System (ADS)

    Baddour, O.; Djellouli, Y.

    2003-04-01

    Northwest Africa defined here as the area including Morocco, Algeria and Tunisia, occupies a large territory in North Africa with an area exceeding 3.5 million km2. The geographical contrast is very important: while most of the southern part is desert, the northern and northwestern parts exhibit a contrasting geography including large flat areas in the western part of Morocco, northern Algeria and eastern part of Tunisia and the formidable Atlas mountains barrier extends from south west of Morocco toward north west of Tunisia crossing central Morocco and north Algeria. Agriculture is one of major socio-economic activities in the region with an extensive cash-crop for exporting to Europe especially from Morocco and Tunisia. The influence of the recurring droughts during the 80s and 90s was very crucial for the economic and societal aspects of the region. In Morocco, severe droughts have caused GDP fluctuation within past 20 years from 10% increase down to negative values in some particular years. Recent studies have investigated seasonal rainfall variability and prediction over MOROCCO in the framework of regional and international collaboration. Results from this work has shown that the main general circulation feature associated with the rainfall variability within Morocco is the North Atlantic Oscillation. The relationship is in fact due to the major role played by the AZORES high pressure with its role in modulating the main position of the active synoptic systems in the north Atlantic area and therefore in modulating the frequency and the intensity of the weather systems that impact the western part of the region. Mediterranean sea plays also major role in the mid of the region. In this paper we applied EOF technique on 500 hPa. The data used are monthly reanalysis NCEP/NCAR analyses for November from 1960 to 1990 climatological time series. Correlation analysis is then performed between EOF time series and global 4x4 degre SST anomalies. The results we

  12. Climate variability and change scenarios for a marine commodity: Modelling small pelagic fish, fisheries and fishmeal in a globalized market

    NASA Astrophysics Data System (ADS)

    Merino, Gorka; Barange, Manuel; Mullon, Christian

    2010-04-01

    The world's small pelagic fish populations, their fisheries, fishmeal and fish oil production industries and markets are part of a globalised production and consumption system. The potential for climate variability and change to alter the balance in this system is explored by means of bioeconomic models at two different temporal scales, with the objective of investigating the interactive nature of environmental and human-induced changes on this globalised system. Short-term (interannual) environmental impacts on fishmeal production are considered by including an annual variable production rate on individual small pelagic fish stocks over a 10-year simulation period. These impacts on the resources are perceived by the fishmeal markets, where they are confronted by two aquaculture expansion hypotheses. Long-term (2080) environmental impacts on the same stocks are estimated using long-term primary production predictions as proxies for the species' carrying capacities, rather than using variable production rates, and are confronted on the market side by two alternative fishmeal management scenarios consistent with IPCC-type storylines. The two scenarios, World Markets and Global Commons, are parameterized through classic equilibrium solutions for a global surplus production bioeconomic model, namely maximum sustainable yield and open access, respectively. The fisheries explicitly modelled in this paper represent 70% of total fishmeal production, thus encapsulating the expected dynamics of the global production and consumption system. Both short and long-term simulations suggest that the sustainability of the small pelagic resources, in the face of climate variability and change, depends more on how society responds to climate impacts than on the magnitude of climate alterations per se.

  13. Short-term memory binding deficits in Alzheimer's disease.

    PubMed

    Parra, Mario A; Abrahams, Sharon; Fabi, Katia; Logie, Robert; Luzzi, Simona; Della Sala, Sergio

    2009-04-01

    Alzheimer's disease impairs long term memories for related events (e.g. faces with names) more than for single events (e.g. list of faces or names). Whether or not this associative or 'binding' deficit is also found in short-term memory has not yet been explored. In two experiments we investigated binding deficits in verbal short-term memory in Alzheimer's disease. Experiment 1: 23 patients with Alzheimer's disease and 23 age and education matched healthy elderly were recruited. Participants studied visual arrays of objects (six for healthy elderly and four for Alzheimer's disease patients), colours (six for healthy elderly and four for Alzheimer's disease patients), unbound objects and colours (three for healthy elderly and two for Alzheimer's disease patients in each of the two categories), or objects bound with colours (three for healthy elderly and two for Alzheimer's disease patients). They were then asked to recall the items verbally. The memory of patients with Alzheimer's disease for objects bound with colours was significantly worse than for single or unbound features whereas healthy elderly's memory for bound and unbound features did not differ. Experiment 2: 21 Alzheimer's disease patients and 20 matched healthy elderly were recruited. Memory load was increased for the healthy elderly group to eight items in the conditions assessing memory for single or unbound features and to four items in the condition assessing memory for the binding of these features. For Alzheimer's disease patients the task remained the same. This manipulation permitted the performance to be equated across groups in the conditions assessing memory for single or unbound features. The impairment in Alzheimer's disease patients in recalling bound objects reported in Experiment 1 was replicated. The binding cost was greater than that observed in the healthy elderly group, who did not differ in their performance for bound and unbound features. Alzheimer's disease grossly impairs the

  14. Power system very short-term load prediction

    SciTech Connect

    Trudnowski, D.J.; Johnson, J.M.; Whitney, P.

    1997-02-01

    A fundamental objective of a power-system operating and control scheme is to maintain a match between the system`s overall real-power load and generation. To accurately maintain this match, modern energy management systems require estimates of the future total system load. Several strategies and tools are available for estimating system load. Nearly all of these estimate the future load in 1-hour steps over several hours (or time frames very close to this). While hourly load estimates are very useful for many operation and control decisions, more accurate estimates at closer intervals would also be valuable. This is especially true for emerging Area Generation Control (AGC) strategies such as look-ahead AGC. For these short-term estimation applications, future load estimates out to several minutes at intervals of 1 to 5 minutes are required. The currently emerging operation and control strategies being developed by the BPA are dependent on accurate very short-term load estimates. To meet this need, the BPA commissioned the Pacific Northwest National Laboratory (PNNL) and Montana Tech (an affiliate of the University of Montana) to develop an accurate load prediction algorithm and computer codes that automatically update and can reliably perform in a closed-loop controller for the BPA system. The requirements include accurate load estimation in 5-minute steps out to 2 hours. This report presents the results of this effort and includes: a methodology and algorithms for short-term load prediction that incorporates information from a general hourly forecaster; specific algorithm parameters for implementing the predictor in the BPA system; performance and sensitivity studies of the algorithms on BPA-supplied data; an algorithm for filtering power system load samples as a precursor to inputting into the predictor; and FORTRAN 77 subroutines for implementing the algorithms.

  15. Short-term prospective spirometric study of new coal miners

    SciTech Connect

    Hankinson, J.L.; Hodous, T.K.

    1982-09-01

    This study examined prospectively a small cohort (N=116) of new coal miners with questionnaires and spirometry. Data collection began just prior to underground employment and extended over a two year period at 6 month intervals to address the question or short-term adverse occupational pulmonary effects and their relationship to outward migration from the industry. A comparison of the initial (unexposed) and six month (exposed) changes in lung function over the work shift was also conducted to detect an acute effect due to dust, which might be related to chronic decline in lung function.

  16. Short-term energy outlook, quarterly projections, second quarter 1998

    SciTech Connect

    1998-04-01

    The Energy Information Administration (EIA) prepares quarterly short-term energy supply, demand, and price projections. The details of these projections, as well as monthly updates, are available on the Internet at: www.eia.doe.gov/emeu/steo/pub/contents.html. The paper discusses outlook assumptions; US energy prices; world oil supply and the oil production cutback agreement of March 1998; international oil demand and supply; world oil stocks, capacity, and net trade; US oil demand and supply; US natural gas demand and supply; US coal demand and supply; US electricity demand and supply; US renewable energy demand; and US energy demand and supply sensitivities. 29 figs., 19 tabs.

  17. Short-term bioconcentration studies of Np in freshwater biota

    SciTech Connect

    Poston, T.M.; Klopfer, D.C.; Simmons, M.A. )

    1990-12-01

    Short-term laboratory exposures were conducted to determine the potential accumulation of Np in aquatic organisms. Concentration factors were highest in green algae. Daphnia magna, a filter-feeding crustacean, accumulated Np at levels one order of magnitude greater than the amphipod Gammarus sp., an omnivorous substrate feeder. Accumulation of Np in juvenile rainbow trout (Oncorhynchus mykiss) was highest in carcass (generally greater than 78% of the total body burden) and lowest in fillets. Recommended concentration factors for Np, based on fresh weight, were 300 for green algae, 100 for filter-feeding invertebrates, for nonfilter-feeding invertebrates, 10 for whole fish, and one for fish flesh.

  18. MHz gravitational waves from short-term anisotropic inflation

    NASA Astrophysics Data System (ADS)

    Ito, Asuka; Soda, Jiro

    2016-04-01

    We reveal the universality of short-term anisotropic inflation. As a demonstration, we study inflation with an exponential type gauge kinetic function which is ubiquitous in models obtained by dimensional reduction from higher dimensional fundamental theory. It turns out that an anisotropic inflation universally takes place in the later stage of conventional inflation. Remarkably, we find that primordial gravitational waves with a peak amplitude around 10-26~ 10-27 are copiously produced in high-frequency bands 10 MHz~100 MHz. If we could detect such gravitational waves in future, we would be able to probe higher dimensional fundamental theory.

  19. Short-term energy outlook. Volume 2. Methodology

    NASA Astrophysics Data System (ADS)

    1983-05-01

    Recent changes in forecasting methodology for nonutility distillate fuel oil demand and for the near-term petroleum forecasts are discussed. The accuracy of previous short-term forecasts of most of the major energy sources published in the last 13 issues of the Outlook is evaluated. Macroeconomic and weather assumptions are included in this evaluation. Energy forecasts for 1983 are compared. Structural change in US petroleum consumption, the use of appropriate weather data in energy demand modeling, and petroleum inventories, imports, and refinery runs are discussed.

  20. Short-term memory load and pronunciation rate

    NASA Technical Reports Server (NTRS)

    Schweickert, Richard; Hayt, Cathrin

    1988-01-01

    In a test of short-term memory recall, two subjects attempted to recall various lists. For unpracticed subjects, the time it took to read the list is a better predictor of immediate recall than the number of items on the list. For practiced subjects, the two predictors do about equally well. If the items that must be recalled are unfamiliar, it is advantageous to keep the items short to pronounce. On the other hand, if the same items will be encountered over and over again, it is advantageous to make them distinctive, even at the cost of adding to the number of syllables.

  1. Short-term frequency stability of the Rb-87 maser.

    NASA Technical Reports Server (NTRS)

    Tetu, M.; Busca, G.; Vanier, J.

    1973-01-01

    Measurements of the short-term stability of the Rb-87 maser as a function of the maser power output and the receiver cutoff frequency are reported. The experimental data are compared to theoretical results obtained from an approximate theory. In this theory the transfer function of the maser for thermal noise is derived, and the spectral density of the phase fluctuations is calculated. An analytical expression for the 'Allan variance' is also given. A comparison of the stability of the Rb-87 maser with existing frequency standards shows its superiority for averaging times less than 1 sec.

  2. Agricultural management options for climate variability and change: conservation tillage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adapting to climate variability and change can be achieved through a broad range of management alternatives and technological advances. This publication is focused on the use of conservation tillage in crop production systems. The publication outlines ways that conservation tillage can reduce risk r...

  3. 2500 Years of European Climate Variability and Human Susceptibility

    NASA Astrophysics Data System (ADS)

    Büntgen, Ulf; Tegel, Willy; Nicolussi, Kurt; McCormick, Michael; Frank, David; Trouet, Valerie; Kaplan, Jed O.; Herzig, Franz; Heussner, Karl-Uwe; Wanner, Heinz; Luterbacher, Jürg; Esper, Jan

    2011-02-01

    Climate variations influenced the agricultural productivity, health risk, and conflict level of preindustrial societies. Discrimination between environmental and anthropogenic impacts on past civilizations, however, remains difficult because of the paucity of high-resolution paleoclimatic evidence. We present tree ring-based reconstructions of central European summer precipitation and temperature variability over the past 2500 years. Recent warming is unprecedented, but modern hydroclimatic variations may have at times been exceeded in magnitude and duration. Wet and warm summers occurred during periods of Roman and medieval prosperity. Increased climate variability from ~250 to 600 C.E. coincided with the demise of the western Roman Empire and the turmoil of the Migration Period. Such historical data may provide a basis for counteracting the recent political and fiscal reluctance to mitigate projected climate change.

  4. America's water risk: Current demand and climate variability

    NASA Astrophysics Data System (ADS)

    Devineni, Naresh; Lall, Upmanu; Etienne, Elius; Shi, Daniel; Xi, Chen

    2015-04-01

    A new indicator of drought-induced water stress is introduced and applied at the county level in the USA. Unlike most existing drought metrics, we directly consider current daily water demands and renewable daily water supply to estimate the potential stress. Water stress indices developed include the Normalized Deficit Cumulated to represent multiyear droughts by computing the maximum cumulative deficit between demand and supply over the study period (1949-2009) and the Normalized Deficit Index representing drought associated with maximum cumulative deficit each year. These water stress indices map directly to storage requirements needed to buffer multiyear and within-year climate variability and can reveal the dependence on exogenous water transferred by rivers/canals to the area. Future climate change and variability can be also incorporated into this framework to inform climate-driven drought for additional storage development and potential applications of water trading across counties.

  5. Implementation of a Time Series Analysis for the Assessment of the Role of Climate Variability in a Post-Disturbance Savanna System

    NASA Astrophysics Data System (ADS)

    Gibbes, C.; Southworth, J.; Waylen, P. R.

    2013-05-01

    How do climate variability and climate change influence vegetation cover and vegetation change in savannas? A landscape scale investigation of the effect of changes in precipitation on vegetation is undertaken through the employment of a time series analysis. The multi-national study region is located within the Kavango-Zambezi region, and is delineated by the Okavango, Kwando, and Zambezi watersheds. A mean-variance time-series analysis quantifies vegetation dynamics and characterizes vegetation response to climate. The spatially explicit approach used to quantify the persistence of vegetation productivity permits the extraction of information regarding long term climate-landscape dynamics. Results show a pattern of reduced mean annual precipitation and increased precipitation variability across key social and ecological areas within the study region. Despite decreased mean annual precipitation since the mid to late 1970's vegetation trends predominantly indicate increasing biomass. The limited areas which have diminished vegetative cover relate to specific vegetation types, and are associated with declines in precipitation variability. Results indicate that in addition to short term changes in vegetation cover, long term trends in productive biomass are apparent, relate to spatial differences in precipitation variability, and potentially represent shifts vegetation composition. This work highlights the importance of time-series analyses for examining climate-vegetation linkages in a spatially explicit manner within a highly vulnerable region of the world.

  6. Long- and short-term temperature responses of microbially-mediated boreal soil organic matter transformations

    NASA Astrophysics Data System (ADS)

    Min, K.; Buckeridge, K. M.; Edwards, K. A.; Ziegler, S. E.; Billings, S. A.

    2015-12-01

    Microorganisms use exoenzymes to decay soil organic matter into assimilable substrates, some of which are transformed into CO2. Microbial CO2 efflux contributes up to 60% of soil respiration, a feature that can change with temperature due to altered exoenzyme activities (short-term) and microbial communities producing different exoenzymes (longer-term). Often, however, microbial temperature responses are masked by factors that also change with temperature in soil, making accurate projections of microbial CO2 efflux with warming challenging. Using soils along a natural climate gradient similar in most respects except for temperature regime (Newfoundland Labrador Boreal Ecosystem Latitudinal Transect), we investigated short-vs. long-term temperature responses of microbially-mediated organic matter transformations. While incubating soils at 5, 15, and 25°C for 84 days, we measured exoenzyme activities, CO2 efflux rates and biomass, and extracted DNA at multiple times. We hypothesized that short-term, temperature-induced increases in exoenzyme activities and CO2 losses would be smaller in soils from warmer regions, because microbes presumably adapted to warmer regions should use assimilable substrates more efficiently and thus produce exoenzymes at a lower rate. While incubation temperature generally induced greater exoenzyme activities (p<0.001), exoenzymes' temperature responses depended on enzymes and regions (p<0.001). Rate of CO2 efflux was affected by incubation temperature (P<0.001), but not by region. Microbial biomass and DNA sequencing will reveal how microbial community abundance and composition change with short-vs. longer-term temperature change. Though short-term microbial responses to temperature suggest higher CO2 efflux and thus lower efficiency of resource use with warming, longer-term adaptations of microbial communities to warmer climates remain unknown; this work helps fill that knowledge gap.

  7. Integrating short-term and long-term forecasting with reservoir optimisation; Mantaro Basin, Peru.

    NASA Astrophysics Data System (ADS)

    Jensen, R. A.; Lasarte, A.; Butts, M. B.

    2009-04-01

    Operational water management often requires a trade-off between short-term and long-term water demands, where short-term demands are driven for example by hydropower generation and flood protection requirements and the long-term demands by water and irrigation supply, sustainable reservoir management and the seasonal impacts of snow melt or climate. This paper presents an operational decision support system designed to forecast and optimise reservoir operations in both the short-term and long-term. The system has been established for the 20,000 km2 Mantaro river basin located in the high Andes with altitudes ranging from 3500 to nearly 6000 m.a.s.l.. The two main power stations at Tablachaca have a combined capacity of more than 1000 MW that supplies 30% of Peru's electrical energy. In addition, the basin's water resources supply extensive agricultural areas, an urban population and mining activities and sustain important ecological habitats. In this paper, the methodologies used for the integrating short-term and long-term forecasting are presented together with their application to the optimal operation of reservoirs. A key element in the system is the MIKE BASIN modelling tool. The system uses several modelling capabilities of MIKE BASIN: rainfall-runoff, reservoir operation, hydropower production, and river flow routing. The system also takes advantage of long-term forecasts (based on statistical information) and short-term forecasts (based on telemetry data). The continually updated runoff and flow forecasts enter the optimization, which applies the Model Predictive Control principle for MIKE BASIN as the core simulation model. For each optimization, a non-linear program algorithm is used to find the best release strategy. On the basis of the forecasted inflows and the real time data the system suggests to the user from which reservoirs to release water for alleviation of possible forecasted deficits. In addition to the Tablachaca scheme the model accounts for

  8. Response of closed basin lakes to interannual climate variability

    NASA Astrophysics Data System (ADS)

    Huybers, Kathleen; Rupper, Summer; Roe, Gerard H.

    2016-06-01

    Lakes are key indicators of a region's hydrological cycle, directly reflecting the basin-wide balance between precipitation and evaporation. Lake-level records are therefore valuable repositories of climate history. However, the interpretation of such records is not necessarily straightforward. Lakes act as integrators of the year-to-year fluctuations in precipitation and evaporation that occur even in a constant climate. Therefore lake levels can exhibit natural, unforced fluctuations that persist on timescales of decades or more. This behavior is important to account for when distinguishing between true climate change and interannual variability as the cause of past lake-level fluctuations. We demonstrate the operation of this general principle for the particular case-study of the Great Salt Lake, which has long historical lake-level and climatological records. We employ both full water-balance and linear models. Both models capture the timing and size of the lake's historical variations. We then model the lake's response to much longer synthetic time series of precipitation and evaporation calibrated to the observations, and compare the magnitude and frequency of the modeled response to the Great Salt Lake's historical record. We find that interannual climate variability alone can explain much of the decadal-to-centennial variations in the lake-level record. Further, analytic solutions to the linear model capture much of the full model's behavior, but fail to predict the most extreme lake-level variations. We then apply the models to other lake geometries, and evaluate how the timing and amplitude of a lake-level response differs with climatic and geometric setting. A lake's response to a true climatic shift can only be understood in the context of these expected persistent lake-level variations. On the basis of these results, we speculate that lake response to interannual climate variability may play an important part in explaining much of Holocene lake

  9. Temperature, global climate change and food security

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accelerated climate change is expected to have a significant, but variable impact on the world’s major cropping zones. Crops will experience increasingly warmer, drier and more variable growing conditions in the temperate to subtropical latitudes towards 2050 and beyond. Short-term (1-5 day) spikes ...

  10. Plant community controls on short-term ecosystem nitrogen retention.

    PubMed

    de Vries, Franciska T; Bardgett, Richard D

    2016-05-01

    Retention of nitrogen (N) is a critical ecosystem function, especially in the face of widespread anthropogenic N enrichment; however, our understanding of the mechanisms involved is limited. Here, we tested under glasshouse conditions how plant community attributes, including variations in the dominance, diversity and range of plant functional traits, influence N uptake and retention in temperate grassland. We added a pulse of (15) N to grassland plant communities assembled to represent a range of community-weighted mean plant traits, trait functional diversity and divergence, and species richness, and measured plant and microbial uptake of (15) N, and leaching losses of (15) N, as a short-term test of N retention in the plant-soil system. Root biomass, herb abundance and dominant plant traits were the main determinants of N retention in the plant-soil system: greater root biomass and herb abundance, and lower root tissue density, increased plant (15) N uptake, while higher specific leaf area and root tissue density increased microbial (15) N uptake. Our results provide novel, mechanistic insight into the short-term fate of N in the plant-soil system, and show that dominant plant traits, rather than trait functional diversity, control the fate of added N in the plant-soil system. PMID:26749302

  11. Short-term stability of Borrelia garinii in cerebrospinal fluid.

    PubMed

    Berenová, Dagmar; Krsek, Daniel; Šípková, Lenka; Lukavská, Alena; Malý, Marek; Kurzová, Zuzana; Hořejší, Jan; Kodym, Petr

    2016-01-01

    The aim of our study was to find out the optimal conditions for short-term storage of cerebrospinal fluid (CSF) samples for direct diagnosis of Lyme disease. A mixture of Borrelia-negative CSFs spiked with a defined amount of cultured Borrelia garinii was used. Borrelia stability was investigated over 7 days at four different temperatures [room temperature (RT), +4, -20 and -70 °C]. Quantitative changes in CSF Borrelia were measured by quantitative PCR (qPCR), and morphological changes in the spirochetes were observed by transmission electron microscopy (TEM). These qPCR results were statistically evaluated. We found +4 °C to be an optimal temperature for short-term storage of CSF samples intended for TEM observation. There was no significant difference between the temperatures tested in the average quantity of Borrelia measured by qPCR. On the contrary, electron optical diagnosis of frozen samples and samples stored at RT showed destructive morphological changes and decreased spirochete counts. Our results show that optimal conditions for the pre-analytical phase of investigation of one type of material can differ depending on the diagnostic method employed. PMID:26104540

  12. Robust Short-Term Memory without Synaptic Learning

    PubMed Central

    Johnson, Samuel; Marro, J.; Torres, Joaquín J.

    2013-01-01

    Short-term memory in the brain cannot in general be explained the way long-term memory can – as a gradual modification of synaptic weights – since it takes place too quickly. Theories based on some form of cellular bistability, however, do not seem able to account for the fact that noisy neurons can collectively store information in a robust manner. We show how a sufficiently clustered network of simple model neurons can be instantly induced into metastable states capable of retaining information for a short time (a few seconds). The mechanism is robust to different network topologies and kinds of neural model. This could constitute a viable means available to the brain for sensory and/or short-term memory with no need of synaptic learning. Relevant phenomena described by neurobiology and psychology, such as local synchronization of synaptic inputs and power-law statistics of forgetting avalanches, emerge naturally from this mechanism, and we suggest possible experiments to test its viability in more biological settings. PMID:23349664

  13. Short-Term Test Results: Multifamily Home Energy Efficiency Retrofit

    SciTech Connect

    Lyons, J.

    2013-01-01

    Multifamily deep energy retrofits (DERs) represent great potential for energy savings, while also providing valuable insights on research-generated efficiency measures, cost-effectiveness metrics, and risk factor strategies for the multifamily housing industry. The Bay Ridge project is comprised of a base scope retrofit with a goal of achieving 30% savings (relative to pre-retrofit), and a DER scope with a goal of 50% savings (relative to pre-retrofit). The base scope has been applied to the entire complex, except for one 12-unit building which underwent the DER scope. Findings from the implementation, commissioning, and short-term testing at Bay Ridge include air infiltration reductions of greater than 60% in the DER building; a hybrid heat pump system with a Savings to Investment Ratio (SIR) > 1 (relative to a high efficiency furnace) which also provides the resident with added incentive for energy savings; and duct leakage reductions of > 60% using an aerosolized duct sealing approach. Despite being a moderate rehab instead of a gut rehab, the Bay Ridge DER is currently projected to achieve energy savings ≥ 50% compared to pre-retrofit, and the short-term testing supports this estimate.

  14. Statistical approaches to short-term electricity forecasting

    NASA Astrophysics Data System (ADS)

    Kellova, Andrea

    The study of the short-term forecasting of electricity demand has played a key role in the economic optimization of the electric energy industry and is essential for power systems planning and operation. In electric energy markets, accurate short-term forecasting of electricity demand is necessary mainly for economic operations. Our focus is directed to the question of electricity demand forecasting in the Czech Republic. Firstly, we describe the current structure and organization of the Czech, as well as the European, electricity market. Secondly, we provide a complex description of the most powerful external factors influencing electricity consumption. The choice of the most appropriate model is conditioned by these electricity demand determining factors. Thirdly, we build up several types of multivariate forecasting models, both linear and nonlinear. These models are, respectively, linear regression models and artificial neural networks. Finally, we compare the forecasting power of both kinds of models using several statistical accuracy measures. Our results suggest that although the electricity demand forecasting in the Czech Republic is for the considered years rather a nonlinear than a linear problem, for practical purposes simple linear models with nonlinear inputs can be adequate. This is confirmed by the values of the empirical loss function applied to the forecasting results.

  15. Short-term energy outlook, Annual supplement 1995

    SciTech Connect

    1995-07-25

    This supplement is published once a year as a complement to the Short- Term Energy Outlook, Quarterly Projections. The purpose of the Supplement is to review the accuracy of the forecasts published in the Outlook, make comparisons with other independent energy forecasts, and examine current energy topics that affect the forecasts. Chap. 2 analyzes the response of the US petroleum industry to the recent four Federal environmental rules on motor gasoline. Chap. 3 compares the EIA base or mid case energy projections for 1995 and 1996 (as published in the first quarter 1995 Outlook) with recent projections made by four other major forecasting groups. Chap. 4 evaluates the overall accuracy. Chap. 5 presents the methology used in the Short- Term Integrated Forecasting Model for oxygenate supply/demand balances. Chap. 6 reports theoretical and empirical results from a study of non-transportation energy demand by sector. The empirical analysis involves the short-run energy demand in the residential, commercial, industrial, and electrical utility sectors in US.

  16. Calcium Channels and Short-term Synaptic Plasticity*

    PubMed Central

    Catterall, William A.; Leal, Karina; Nanou, Evanthia

    2013-01-01

    Voltage-gated Ca2+ channels in presynaptic nerve terminals initiate neurotransmitter release in response to depolarization by action potentials from the nerve axon. The strength of synaptic transmission is dependent on the third to fourth power of Ca2+ entry, placing the Ca2+ channels in a unique position for regulation of synaptic strength. Short-term synaptic plasticity regulates the strength of neurotransmission through facilitation and depression on the millisecond time scale and plays a key role in encoding information in the nervous system. CaV2.1 channels are the major source of Ca2+ entry for neurotransmission in the central nervous system. They are tightly regulated by Ca2+, calmodulin, and related Ca2+ sensor proteins, which cause facilitation and inactivation of channel activity. Emerging evidence reviewed here points to this mode of regulation of CaV2.1 channels as a major contributor to short-term synaptic plasticity of neurotransmission and its diversity among synapses. PMID:23400776

  17. Short-term energy outlook. Quarterly projections, third quarter 1996

    SciTech Connect

    1996-07-01

    The Energy Information Administration (EIA) prepares quarterly, short-term energy supply, demand, and price projections for publication in January, April, July, and October in the Outlook. The forecast period for this issue of the Outlook extends from the third quarter of 1996 through the fourth quarter of 1997. Values for the second quarter of 1996, however, are preliminary EIA estimates (for example, some monthly values for petroleum supply and disposition are derived in part from weekly data reported in the Weekly Petroleum Status Report) or are calculated from model simulations using the latest exogenous information available (for example, electricity sales and generation are simulated using actual weather data). The historical energy data, compiled in the third quarter 1996 version of the Short-Term Integrated Forecasting System (STIFS) database, are mostly EIA data regularly published in the Monthly energy Review, Petroleum Supply Monthly, and other EIA publications. Minor discrepancies between the data in these publications and the historical data in this Outlook are due to independent rounding. The STIFS database is archived quarterly and is available from the National Technical Information Service.

  18. Prediction and predictability of North American seasonal climate variability

    NASA Astrophysics Data System (ADS)

    Infanti, Johnna M.

    Climate prediction on short time-scales such as months to seasons is of broad and current interest in the scientific research community. Monthly and seasonal climate prediction of variables such as precipitation, temperature, and sea surface temperature (SST) has implications for users in the agricultural and water management domains, among others. It is thus important to further understand the complexities of prediction of these variables using the most recent practices in climate prediction. The overarching goal of this dissertation is to determine the important contributions to seasonal prediction skill, predictability, and variability over North America using current climate prediction models and approaches. This dissertation aims to study a variety of approaches to seasonal climate prediction of variables over North America, including both climate prediction systems and methods of analysis. We utilize the North American Multi-Model Ensemble (NMME) System for Intra-Seasonal to Inter-Annual Prediction (ISI) to study seasonal climate prediction skill of North American and in particular for southeast US precipitation. We find that NMME results are often equal to or better than individual model results in terms of skill, as expected, making it a reasonable choice for southeast US seasonal climate predictions. However, climate models, including those involved in NMME, typically overestimate eastern Pacific warming during central Pacific El Nino events, which can affect regions that are influenced by teleconnections, such as the southeast US. Community Climate System Model version 4.0 (CCSM4) hindacasts and forecasts are included in NMME, and we preform a series of experiments that examine contributions to skill from certain drivers of North American climate prediction. The drivers we focus on are sea surface temperatures (SSTs) and their accuracy, land and atmosphere initialization, and ocean-atmosphere coupling. We compare measures of prediction skill of

  19. Comparison of Decadal AMOC Variability Among Climate Models

    NASA Astrophysics Data System (ADS)

    Klinger, B. A.; Garuba, O. A.

    2012-12-01

    Atmosphere-ocean general circulation models (AOGCM's) often exhibit decadal variability of the Atlantic Meridional Overturning Circulation (AMOC), but the nature of this variability shows great quantitative and qualitative differences among different experiments. Here uniform metrics compare AMOC variability among several AOGCM's in preindustrial control runs for the Climate Model Intercomparison Project (CMIP). All the models show decadal variability in meridional overturning. The 3-61 year band is examined to isolate this frequency range. The meridional stream function shows maximum variability in the North Atlantic ranging from about .5 to 1.8 Sv (about 3% to 10% of the time-mean overturning strength), with period (based on the lagged autocorrelation) ranging from about 10 to 25 years for most of the models (50 years for one model). In all models, overturning variability is strongest between 40N and 60N, with a weaker overturning signal propagating across the equator within a few years. Most of the models show a somewhat complex high-latitude density field associated with the meridional overturning, but with a tendency for high density to precede high overturning, as Dong and Sutton (2005) found in a single model. In summary, O(1) Sv North Atlantic decadal overturning variability associated with high latitude density variations is a robust feature of different climate models.

  20. Decadal Variability of Clouds and Comparison with Climate Model Simulations

    NASA Astrophysics Data System (ADS)

    Su, H.; Shen, T. J.; Jiang, J. H.; Yung, Y. L.

    2014-12-01

    An apparent climate regime shift occurred around 1998/1999, when the steady increase of global-mean surface temperature appeared to hit a hiatus. Coherent decadal variations are found in atmospheric circulation and hydrological cycles. Using 30-year cloud observations from the International Satellite Cloud Climatology Project, we examine the decadal variability of clouds and associated cloud radiative effects on surface warming. Empirical Orthogonal Function analysis is performed. After removing the seasonal cycle and ENSO signal in the 30-year data, we find that the leading EOF modes clearly represent a decadal variability in cloud fraction, well correlated with the indices of Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO). The cloud radiative effects associated with decadal variations of clouds suggest a positive cloud feedback, which would reinforce the global warming hiatus by a net cloud cooling after 1998/1999. Climate model simulations driven by observed sea surface temperature are compared with satellite observed cloud decadal variability. Copyright:

  1. Reservoir operation under variable climate: Case of Rozva Dam, Zimbabwe

    NASA Astrophysics Data System (ADS)

    Ncube, S. P.; Makurira, H.; Kaseke, E.; Mhizha, A.

    The challenge of maintaining or improving the quality of rural livelihoods against the increasing threat of climate change (CC) and climate variability (CV) calls for the development of robust and tested systems, tools and procedures for the management of water resources. The research aimed at assessing reservoir operation under variable climate for Rozva Dam, a medium-sized reservoir in Zimbabwe. Rozva Dam is located in the Bikita District of Zimbabwe and has a full supply capacity of 2.8 Mm 3 at a maximum water level of 17.3 m. The research analysed 46 years of rainfall and temperature data to assess climate variability and or change. The CROPWAT model was used to estimate crop water requirements for the adjacent 80 hectare irrigation scheme. The WAFLEX model was applied to simulate the performance of the system under three scenarios: (1) existing demands and operational rules, (2) reduced water availability due to climate change, as predicted by the Ministry of Mines, but with increasing annual demands and (3) climate change situation coupled with change in irrigation technology. The results show a general decreasing linear trend for rainfall although the variance was not statistically significant at p = 0.05. A clearer cyclic pattern was observed for the decadal analysis. An increasing trend in both maximum and minimum temperature was observed although, again, these were not statistically significant with a Spearman’s rank correlation coefficient ( R sp) of below 0.5. The research used rainfall and temperature data as the basis for confirmation climate change and variability in the study area. Analyses show that the area is experiencing more of CV than CC. Modelling results show that the reservoir can satisfy current demands but will fail to cope under the forecasted increase in demand. The conclusions from the research are that the available water resources in the studied system are sufficient to satisfy the current demands. The predicted level of climate

  2. Second-Language Learners' Identification of Target-Language Phonemes: A Short-Term Phonetic Training Study

    ERIC Educational Resources Information Center

    Cebrian, Juli; Carlet, Angelica

    2014-01-01

    This study examined the effect of short-term high-variability phonetic training on the perception of English /b/, /v/, /d/, /ð/, /ae/, /? /, /i/, and /i/ by Catalan/Spanish bilinguals learning English as a foreign language. Sixteen English-major undergraduates were tested before and after undergoing a four-session perceptual training program…

  3. Impacts of Short-Term Meteorological Fluctuations on Near-Surface Ground Temperatures in Spitsbergen, Svalbard

    NASA Astrophysics Data System (ADS)

    Strand, S. M.; Christiansen, H. H.

    2015-12-01

    The state of permafrost in a given area is dependent on heat balance, which is largely controlled by major trends in climate. However, smaller-scale meteorological events can impact the thermal regime as well, depending on a number of ground surface factors. This project investigates the impact of short-term meteorological fluctuations on near-surface ground temperatures in central Spitsbergen, Svalbard, and identifies the depths at which these changes are perceptible. The Svalbard archipelago is subject to significant air temperature fluctuations due to its maritime climate; this can result in wintertime rain events. Even when snow is present, rain has the potential to notably affect near-surface ground temperatures. A few studies have examined Svalbard ground temperatures during specific wintertime warm periods, but no previous research has utilized the available long-term active layer and permafrost temperature data to compare distinct events. Though summer air temperatures on Svalbard are more stable, particularly warm intervals alter active layer thaw progression. By comparing high-resolution air temperature data with high-resolution ground temperature data, the temporal and spatial impact of short-term meteorological fluctuations is assessed and compared between sites from varying locations and lithology.

  4. Effects of climate variability on global scale flood risk

    NASA Astrophysics Data System (ADS)

    Ward, P.; Dettinger, M. D.; Kummu, M.; Jongman, B.; Sperna Weiland, F.; Winsemius, H.

    2013-12-01

    In this contribution we demonstrate the influence of climate variability on flood risk. Globally, flooding is one of the worst natural hazards in terms of economic damages; Munich Re estimates global losses in the last decade to be in excess of $240 billion. As a result, scientifically sound estimates of flood risk at the largest scales are increasingly needed by industry (including multinational companies and the insurance industry) and policy communities. Several assessments of global scale flood risk under current and conditions have recently become available, and this year has seen the first studies assessing how flood risk may change in the future due to global change. However, the influence of climate variability on flood risk has as yet hardly been studied, despite the fact that: (a) in other fields (drought, hurricane damage, food production) this variability is as important for policy and practice as long term change; and (b) climate variability has a strong influence in peak riverflows around the world. To address this issue, this contribution illustrates the influence of ENSO-driven climate variability on flood risk, at both the globally aggregated scale and the scale of countries and large river basins. Although it exerts significant and widespread influences on flood peak discharges in many parts of the world, we show that ENSO does not have a statistically significant influence on flood risk once aggregated to global totals. At the scale of individual countries, though, strong relationships exist over large parts of the Earth's surface. For example, we find particularly strong anomalies of flood risk in El Niño or La Niña years (compared to all years) in southern Africa, parts of western Africa, Australia, parts of Central Eurasia (especially for El Niño), the western USA (especially for La Niña), and parts of South America. These findings have large implications for both decadal climate-risk projections and long-term future climate change

  5. Deciphering the record of short-term base-level changes in Gilbert-type deltas

    NASA Astrophysics Data System (ADS)

    Gobo, Katarina; Ghinassi, Massimiliano; Nemec, Wojciech

    2016-04-01

    -front accommodation driven by short-term base-level changes, with some accompanying inevitable 'noise' in the facies record due to the system autogenic variability and regional climatic fluctuations. Comparison of delta coeval foreset and toeset/bottomset deposits in a delta shows further a reverse pattern of reciprocal changes in facies assemblages, with the TFA assemblage of foreset deposits passing downdip into a DFA assemblage of delta-foot deposits, and the DFA assemblage of foreset deposits passing downdip into a TFA assemblage. This reverse reciprocal alternation of TFA and DFA facies assemblages is attributed to the delta-slope own morphodynamics. When the delta slope is dominated by deposition of debrisflows, only the most diluted turbulent flows and chute bypassing turbidity currents are reaching the delta-foot zone. When the delta slope is dominated by turbiditic sedimentation, larger chutes and gullies form - triggering and conveying debrisflows to the foot zone. These case studies as a whole shed a new light on the varying pattern of subaqueous sediment dispersal processes in an evolving Gilbert-type deltaic system and point to an the attractive possibility of the recognition of a 'hidden' record of base-level changes on the basis of detailed facies analysis.

  6. Deciphering the driving forces of short-term erosion in glacially impacted landscapes, an example from the Western Alps

    NASA Astrophysics Data System (ADS)

    Glotzbach, Christoph; van der Beek, Peter; Carcaillet, Julien; Delunel, Romain

    2013-04-01

    Tectonic uplift is the main driver of long-term erosion, but climate changes can markedly affect the link between tectonics and erosion, causing transient variations in short-term erosion rate. Here we study the driving forces of short-term erosion rates in the French Western Alps as estimated from in-situ produced cosmogenic 10Be and detrital apatite fission-track thermochronology analysis of stream sediments. Short-term erosion rates from 10Be analyses vary between ~0.27 and ~1.33 mm/yr, similar to rates measured in adjacent areas of the Alps. Part of the data scales positively with elevation, while the full dataset shows a significant positive correlation with steepness index of streams and normalized geophysical relief. Mean long-term exhumation and short-term erosion rates are comparable in areas that are exhuming rapidly (>0.4 km/Myr), but short-term rates are on average two-three (and up to six) times higher than long-term rates in areas where the latter are slow (<0.4 km/Myr). These findings are supported by detrital apatite fission-track age distributions that appear to require similar variations in erosion rates. Major glaciations strongly impacted the external part of the Alps, increasing both long-term exhumation rates as well as relief (e.g. Glotzbach et al. 2011; Häuselmann et al. 2007; Valla et al.). Based on our data, it seems that glacial impact in the more slowly eroding internal part is mainly restricted to relief, which is reflected in high transient short-term erosion rates. The data further reveal that normalized steepness index and ridgeline geophysical relief are well correlated with (and could be used as proxies for) short-term erosion, in contrast to slope, corroborating studies in purely fluvial landscapes. Our study demonstrates that climate change, e.g. through occurrence of major glaciations, can markedly perturb landscapes short-term erosion patterns in regions of tectonically controlled long-term exhumation. Glotzbach C., P.A. van

  7. Revealing Relationships among Relevant Climate Variables with Information Theory

    NASA Technical Reports Server (NTRS)

    Knuth, Kevin H.; Golera, Anthony; Curry, Charles T.; Huyser, Karen A.; Kevin R. Wheeler; Rossow, William B.

    2005-01-01

    The primary objective of the NASA Earth-Sun Exploration Technology Office is to understand the observed Earth climate variability, thus enabling the determination and prediction of the climate's response to both natural and human-induced forcing. We are currently developing a suite of computational tools that will allow researchers to calculate, from data, a variety of information-theoretic quantities such as mutual information, which can be used to identify relationships among climate variables, and transfer entropy, which indicates the possibility of causal interactions. Our tools estimate these quantities along with their associated error bars, the latter of which is critical for describing the degree of uncertainty in the estimates. This work is based upon optimal binning techniques that we have developed for piecewise-constant, histogram-style models of the underlying density functions. Two useful side benefits have already been discovered. The first allows a researcher to determine whether there exist sufficient data to estimate the underlying probability density. The second permits one to determine an acceptable degree of round-off when compressing data for efficient transfer and storage. We also demonstrate how mutual information and transfer entropy can be applied so as to allow researchers not only to identify relations among climate variables, but also to characterize and quantify their possible causal interactions.

  8. Sensitivity of Detection and Attribution of Climate Change to Simulated Climate Variability

    NASA Astrophysics Data System (ADS)

    Imbers, J.; Lopez, A.; Huntingford, C.; Allen, M.

    2011-12-01

    The statement in the IPCC 4th Assessment that most of the observed global warming since the mid-20th-century is "very likely" due to the anthropogenic increase in greenhouse gas depends heavily on the statistical method of optimal fingerprinting and on its estimates of internal climate variability. In particular, the estimation of internally generated variability plays a central role in defining the "goodness-of-fit" between models and observations in both detection and attribution of external influences on climate and in the evaluation of climate models. However, most climate models remain deficient at representing important aspects of interannual and longer time-scale variability. We ask what is the sensitivity of attribution statements to a potential misrepresentation of internally-generated variability by climate models. Thus, we characterize natural variability with two statistical representations, a short and a long memory model both with the same number of parameters and we analyze the sensitivity of detection and attribution to these statistical parameters. We also investigate physically based arguments that could establish a superiority of one model over the other when both are statistically robust on the relatively short time series of a century typically used in the IPCC report. We aim to use the CMIP-5 ensemble to update this statement, accounting for a broader range of consistent model simulations and assessing the impact of the decade of near-stable temperatures post 2000.

  9. A COMPARISON OF WINTER SHORT-TERM AND ANNUAL AVERAGE RADON MEASUREMENTS IN BASEMENTS OF A RADON-PRONE REGION AND EVALUATION OF FURTHER RADON TESTING INDICATORS

    PubMed Central

    Barros, Nirmalla G.; Steck, Daniel J.; Field, R. William

    2014-01-01

    The primary objective of this study was to investigate the temporal variability between basement winter short-term (7 to 10 days) and basement annual radon measurements. Other objectives were to test the short-term measurement’s diagnostic performance at two reference levels and to evaluate its ability to predict annual average basement radon concentrations. Electret ion chamber (short-term) and alpha track (annual) radon measurements were obtained by trained personnel in Iowa residences. Overall, the geometric mean of the short-term radon concentrations (199 Bq m−3) was slightly greater than the geometric mean of the annual radon concentrations (181 Bq m−3). Short-term tests incorrectly predicted that the basement annual radon concentrations would be below 148 Bq m−3 12% of the time and 2% of the time at 74 Bq m−3. The short-term and annual radon concentrations were strongly correlated (r=0.87, p<0.0001). The foundation wall material of the basement was the only significant factor to have an impact on the absolute difference between the short-term and annual measurements. The findings from this study provide evidence of a substantially lower likelihood of obtaining a false negative result from a single short-term test in a region with high indoor radon potential when the reference level is lowered to 74 Bq m−3. PMID:24670901

  10. The role of internal climate variability for interpreting climate change scenarios

    NASA Astrophysics Data System (ADS)

    Maraun, Douglas

    2013-04-01

    When communicating information on climate change, the use of multi-model ensembles has been advocated to sample uncertainties over a range as wide as possible. To meet the demand for easily accessible results, the ensemble is often summarised by its multi-model mean signal. In rare cases, additional uncertainty measures ar