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

    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

  4. 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.

  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. 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).

  16. 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

  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. 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.

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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

  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

    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.

  16. 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.

  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. 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.

  10. 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

  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. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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

  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. 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

  7. 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.

  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. 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.

  3. 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

  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 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.

  12. 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

  13. 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

  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 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

  18. 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

  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. 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

  1. 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

  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. 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

  17. 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.

  18. 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.

  19. 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.

  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. 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

  19. 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.

  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 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.

  3. 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.

  4. 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.

  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. 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.