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Sample records for diurnal activity cycles

  1. Diurnal cycle of convective activity over ocean in the Tropics

    NASA Astrophysics Data System (ADS)

    Hara, Masayuki; Takahashi, Hiroshi; Fujita, Mikiko

    2015-04-01

    In this study, the influence of land mass on the diurnal cycle of convective activity is analyzed. 17-year observation of Tropical Rainfall Measuring Mission (TRMM) 2A25 V7 (1998-2014) Estimated Surface Rain (ESR) is used as a precipitation data. We rasterized the ESR data into 0.1x0.1 degree mesh for each local solar time (LST) of observation. U. S. Geological Survey Global Land Cover Characterization (USGS GLCC) Version 2 data is used for determining the shoreline. As the many studies indicated, the precipitation peak time is about 3 LST over the Tropical ocean near the coastline, and about 15 LST over the Tropical land. Although the total precipitation amount strongly depends on the distance from the shoreline, The phase of the diurnal cycle over the ocean is not dependent on the distance from the nearest shoreline. We also performed a series of ideal experiments with a quasi-three dimensional domain using non-hydrostatic atmospheric model to elucidate the detailed feature of the relationship between land-sea contrast and local convection systems.

  2. Diurnal cycles in serotonin acetyltransferase activity and cyclic GMP content of cultured chick pineal glands.

    PubMed

    Wainwright, S D

    1980-06-12

    Levels of serotonin N-acetyltransferase (NAT: acetul CoA:arylamine N-acetyltransferase; EC 2.1.1.5.) activity in the chick pineal gland exhibit a marked diurnal variation in birds kept under a diurnal cycle of ilumination. Activity begins to rise rapidly at the start of the dark phase of the cycle and reaches maximum levels at mid-dark phase about 25-fold greater than the minimum basal level at mid-light phase. Thereafter, the level of activity declines to the basal level about the start of the light phase. This diurnal cycle in chick pineal NAT activity found in vivo has recently been reproduced in vitro with intact glands incubated in organ culture. The mechanism of the 'biological clock' which regulates these variations in level of chick pineal NAT activity is unknown. However, I now report that chick pineal glands cultured under a diurnal cycle of illumination exhibit a diurnal cycle in content of cyclic GMP which roughly parallels the cycles in NAT activity. In contrast, there was no correlation between variations in pineal content of cyclic AMP and in level of NAT activity. PMID:6250035

  3. An investigation of how radiation may cause accelerated rates of tropical cyclogenesis and diurnal cycles of convective activity

    NASA Astrophysics Data System (ADS)

    Nicholls, M. E.

    2015-03-01

    Recent cloud-resolving numerical modeling results suggest that radiative forcing causes accelerated rates of tropical cyclogenesis and early intensification. Furthermore, observational studies of tropical cyclones have found that oscillations of the cloud canopy areal extent often occur that are clearly related to the solar diurnal cycle. A theory is put forward to explain these findings. The primary mechanism that seems responsible can be considered a refinement of the mechanism proposed by Gray and Jacobson (1977) to explain diurnal variations of oceanic tropical deep cumulus convection. It is hypothesized that differential radiative cooling or heating between a relatively cloud-free environment and a developing tropical disturbance generates circulations that can have very significant influences on convective activity in the core of the system. It is further suggested that there are benefits to understanding this mechanism by viewing it in terms of the lateral propagation of thermally driven gravity wave circulations, also known as buoyancy bores. Numerical model experiments indicate that mean environmental radiative cooling outside the cloud system is playing an important role in causing a significant horizontal differential radiative forcing and accelerating the rate of tropical cyclogenesis. As an expansive stratiform cloud layer forms aloft within a developing system the mean low level radiative cooling is reduced while at mid levels small warming occurs. During the daytime there is not a very large differential radiative forcing between the environment and the cloud system, but at nighttime when there is strong radiative clear sky cooling of the environment it becomes significant. Thermally driven circulations develop, characterized by relatively weak subsidence in the environment but much stronger upward motion in the cloud system. This upward motion leads to a cooling tendency and increased relative humidity. The increased relative humidity at night

  4. An investigation of how radiation may cause accelerated rates of tropical cyclogenesis and diurnal cycles of convective activity

    NASA Astrophysics Data System (ADS)

    Nicholls, M. E.

    2015-08-01

    Recent cloud-resolving numerical modeling results suggest that radiative forcing causes accelerated rates of tropical cyclogenesis and early intensification. Furthermore, observational studies of tropical cyclones have found that oscillations of the cloud canopy areal extent often occur that are clearly related to the solar diurnal cycle. A theory is put forward to explain these findings. The primary mechanism that seems responsible can be considered a refinement of the mechanism proposed by Gray and Jacobson (1977) to explain diurnal variations of oceanic tropical deep cumulus convection. It is hypothesized that differential radiative cooling or heating between a relatively cloud-free environment and a developing tropical disturbance generates circulations that can have very significant influences on convective activity in the core of the system. It is further suggested that there are benefits to understanding this mechanism by viewing it in terms of the lateral propagation of thermally driven gravity wave circulations, also known as buoyancy bores. Numerical model experiments indicate that mean environmental radiative cooling outside the cloud system is playing an important role in causing a significant horizontal differential radiative forcing and accelerating the rate of tropical cyclogenesis. As an expansive stratiform cloud layer forms aloft within a developing system the mean low-level radiative cooling is reduced, while at mid levels small warming occurs. During the daytime there is not a very large differential radiative forcing between the environment and the cloud system, but at nighttime when there is strong radiative clear-sky cooling of the environment it becomes significant. Thermally driven circulations develop, characterized by relatively weak subsidence in the environment but much stronger upward motion in the cloud system. This upward motion leads to a cooling tendency and increased relative humidity. The increased relative humidity at night

  5. Climate Implications of the Moist-convective Diurnal Cycle

    NASA Astrophysics Data System (ADS)

    Ruppert, James

    2016-04-01

    This idealized modeling study is provoked by recent observations from the tropical Indian Ocean (the DYNAMO field campaign), which demonstrate the high degree to which column humidity is modulated by the diurnal cycle of clouds. Under suppressed large-scale conditions, shallow convection prevails, and the diurnal cycles of shortwave radiative heating and sea surface temperature (SST) are at their strongest. In turn, the diurnal cycle of clouds is prominent, which is manifest in daytime cloud deepening and tropospheric moistening in response to boundary layer warming (bearing resemblance to the diurnal cycle over land). An idealized modeling study is performed to 1) assess the driving processes in the diurnal cycle (i.e., SST vs. radiative forcing) and 2) assess whether or not this diurnal cycle rectifies onto longer timescales. A cloud-resolving model framework is employed with the CM1 model (Bryan and Fritsch 2002), wherein a diurnal cycle of SST is prescribed, fully-interactive radiation varies diurnally, and the weak temperature gradient (WTG) approximation is invoked to simulate the feedbacks between the moist convection and large-scale circulation. The results suggest that the diurnal cycle is highly nonlinear, in that the diurnal fluctuation of clouds strongly rectifies onto longer timescales. The diurnal cycle must therefore be regarded as a "forcing mechanism" to the climate system. The vitality and quality of the moist-convective diurnal cycle in climate models may in turn be important to the accuracy of their simulations.

  6. Tropical Cyclone Diurnal Cycle as Observed by TRMM

    NASA Technical Reports Server (NTRS)

    Leppert, Kenneth D., II; Cecil, D. J.

    2015-01-01

    Using infrared satellite data, previous work has shown a consistent diurnal cycle in the pattern of cold cloud tops around mature tropical cyclones. In particular, an increase in the coverage by cold cloud tops often occurs in the inner core of the storm around the time of sunset and subsequently propagates outward to several hundred kilometers over the course of the following day. This consistent cycle may have important implications for structure and intensity changes of tropical cyclones and the forecasting of such changes. Because infrared satellite measurements are primarily sensitive to cloud top, the goal of this study is to use passive and active microwave measurements from the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) and Precipitation Radar (PR), respectively, to examine and better understand the tropical cyclone diurnal cycle throughout a larger depth of the storm's clouds. The National Hurricane Center's best track dataset was used to extract all PR and TMI pixels within 1000 km of each tropical cyclone that occurred in the Atlantic basin between 1998-2011. Then the data was composited according to radius (100-km bins from 0-1000 km) and local standard time (LST; 3-hr bins). Specifically, PR composites involved finding the percentage of pixels with reflectivity greater than or equal to 20 dBZ at various heights (i.e., 2-14 km in increments of 2 km) as a function of radius and time. The 37- and 85- GHz TMI channels are especially sensitive to scattering by precipitation-sized ice in the mid to upper portions of clouds. Hence, the percentage of 37- and 85-GHz polarization corrected temperatures less than various thresholds were calculated using data from all storms as a function of radius and time. For 37 GHz, thresholds of 260 K, 265 K, 270 K, and 275 K were used, and for 85 GHz, thresholds of 200-270 K in increments of 10 K were utilized. Note that convection forced by the interactions of a tropical cyclone with land (e.g., due

  7. Sensitivity of Amazonian TOA flux diurnal cycle composite monthly variability to choice of reanalysis

    NASA Astrophysics Data System (ADS)

    Dodson, J. Brant; Taylor, Patrick C.

    2016-05-01

    Amazonian deep convection experiences a strong diurnal cycle driven by the cycle in surface sensible heat flux, which contributes to a significant diurnal cycle in the top of the atmosphere (TOA) radiative flux. Even when accounting for seasonal variability, the TOA flux diurnal cycle varies significantly on the monthly timescale. Previous work shows evidence supporting a connection between variability in the convective and radiative cycles, likely modulated by variability in monthly atmospheric state (e.g., convective instability). The hypothesized relationships are further investigated with regression analysis of the radiative diurnal cycle and atmospheric state using additional meteorological variables representing convective instability and upper tropospheric humidity. The results are recalculated with three different reanalyses to test the reliability of the results. The radiative diurnal cycle sensitivity to upper tropospheric humidity is about equal in magnitude to that of convective instability. In addition, the results are recalculated with the data subdivided into the wet and dry seasons. Overall, clear-sky radiative effects have a dominant role in radiative diurnal cycle variability during the dry season. Because of this, even in a convectively active region, the clear-sky radiative effects must be accounted for in order to fully explain the monthly variability in diurnal cycle. Finally, while there is general agreement between the different reanalysis-based results when examining the full data time domain (without regard to time of year), there are significant disagreements when the data are divided into wet and dry seasons. The questionable reliability of reanalysis data is a major limitation.

  8. The Effect of the Lunar Cycle on Fecal Cortisol Metabolite Levels and Foraging Ecology of Nocturnally and Diurnally Active Spiny Mice

    PubMed Central

    Dayan, Tamar; Kronfeld-Schor, Noga

    2011-01-01

    We studied stress hormones and foraging of nocturnal Acomys cahirinus and diurnal A. russatus in field populations as well as in two field enclosures populated by both species and two field enclosures with individuals of A. russatus alone. When alone, A. russatus individuals become also nocturnally active. We asked whether nocturnally active A. russatus will respond to moon phase and whether this response will be obtained also in diurnally active individuals. We studied giving-up densities (GUDs) in artificial foraging patches and fecal cortisol metabolite levels. Both species exhibited elevated fecal cortisol metabolite levels and foraged to higher GUDs in full moon nights; thus A. russatus retains physiological response and behavioral patterns that correlate with full moon conditions, as can be expected in nocturnal rodents, in spite of its diurnal activity. The endocrinological and behavioral response of this diurnal species to moon phase reflects its evolutionary heritage. PMID:21829733

  9. Diurnal Thermal Cycling Effects on Backscatter of Thin Sea Ice

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Gow, A. J.; Perovich, D. K.; Hsu, C. C.; Ding, K. H.; Kong, J. A.; Grenfell, T. C.

    1996-01-01

    To invesigate effects on polarimetric backscatter of sea ice grown under diurnal cycling conditions, we carried out an experiment inJanuary 1994 at the outdoor Geophysical Research Facility in the Cold Regions Research and Engineering Laboratory.

  10. New fire diurnal cycle characterizations to improve fire radiative energy assessments made from MODIS observations

    NASA Astrophysics Data System (ADS)

    Andela, N.; Kaiser, J. W.; van der Werf, G. R.; Wooster, M. J.

    2015-08-01

    Accurate near real time fire emissions estimates are required for air quality forecasts. To date, most approaches are based on satellite-derived estimates of fire radiative power (FRP), which can be converted to fire radiative energy (FRE) which is directly related to fire emissions. Uncertainties in these FRE estimates are often substantial. This is for a large part because the most often used low-Earth orbit satellite-based instruments such as the Moderate Resolution Imaging Spectroradiometer (MODIS) have a relatively poor sampling of the usually pronounced fire diurnal cycle. In this paper we explore the spatial variation of this fire diurnal cycle and its drivers using data from the geostationary Meteosat Spinning Enhanced Visible and Infrared Imager (SEVIRI). In addition, we sampled data from the SEVIRI instrument at MODIS detection opportunities to develop two approaches to estimate hourly FRE based on MODIS active fire detections. The first approach ignored the fire diurnal cycle, assuming persistent fire activity between two MODIS observations, while the second approach combined knowledge on the climatology of the fire diurnal cycle with active fire detections to estimate hourly FRE. The full SEVIRI time series, providing full coverage of the fire diurnal cycle, were used to evaluate the results. Our study period comprised of 3 years (2010-2012), and we focused on Africa and the Mediterranean basin to avoid the use of potentially lower quality SEVIRI data obtained at very far off-nadir view angles. We found that the fire diurnal cycle varies substantially over the study region, and depends on both fuel and weather conditions. For example, more "intense" fires characterized by a fire diurnal cycle with high peak fire activity, long duration over the day, and with nighttime fire activity are most common in areas of large fire size (i.e., large burned area per fire event). These areas are most prevalent in relatively arid regions. Ignoring the fire diurnal

  11. Satellite, climatological, and theoretical inputs for modeling of the diurnal cycle of fire emissions

    NASA Astrophysics Data System (ADS)

    Hyer, E. J.; Reid, J. S.; Schmidt, C. C.; Giglio, L.; Prins, E.

    2009-12-01

    The diurnal cycle of fire activity is crucial for accurate simulation of atmospheric effects of fire emissions, especially at finer spatial and temporal scales. Estimating diurnal variability in emissions is also a critical problem for construction of emissions estimates from multiple sensors with variable coverage patterns. An optimal diurnal emissions estimate will use as much information as possible from satellite fire observations, compensate known biases in those observations, and use detailed theoretical models of the diurnal cycle to fill in missing information. As part of ongoing improvements to the Fire Location and Monitoring of Burning Emissions (FLAMBE) fire monitoring system, we evaluated several different methods of integrating observations with different temporal sampling. We used geostationary fire detections from WF_ABBA, fire detection data from MODIS, empirical diurnal cycles from TRMM, and simple theoretical diurnal curves based on surface heating. Our experiments integrated these data in different combinations to estimate the diurnal cycles of emissions for each location and time. Hourly emissions estimates derived using these methods were tested using an aerosol transport model. We present results of this comparison, and discuss the implications of our results for the broader problem of multi-sensor data fusion in fire emissions modeling.

  12. DIURNAL CYCLE OF PRECIPITABLE WATER VAPOR OVER SPAIN

    SciTech Connect

    Ortiz de Galisteo, J. P.; Cachorro, V. E.; Toledano, C.; Torres, B.; Laulainen, Nels S.; Bennouna, Yasmine; de Frutos, A. M.

    2011-05-20

    Despite the importance of the diurnal cycle of precipitable water vapor (PWV), its knowledge is very limited due to the lack of data with sufficient temporal resolution. Currently, from GPS receivers, PWV can be obtained with high temporal resolution in all weather conditions for all hours of the day. In this study we have calculated the diurnal cycle of PWV for ten GPS stations over Spain. The minimum value is reached approximately at the same time at all the stations, ~0400-0500 UTC, whereas the maximum is reached in the second half of the day, but with a larger dispersion of its occurrence between stations. The amplitude of the cycle ranges between 0.72 mm and 1.78 mm. The highest values are recorded at the stations on the Mediterranean coast, with a doubling of the values of the stations on the Atlantic coast or inland. The amplitude of the PWV cycle, relative to the annual mean value, ranges between 8.8 % on the Mediterranean coast and 3.6 % on the Atlantic coast. Two distinctly different seasonal diurnal cycles have been identified, one in winter and other in summer, with spring and autumn being only transition states. The winter cycle is quite similar at all locations, whereas in summer, local effects are felt strongly, making the diurnal cycle quite different between stations. The amplitude of the summer cycle is 1.69 mm, it is almost double the winter one (0.93 mm). Analogous to the annual cycles, the seasonal cycles of the different stations are more similar during the night and early morning hours than during the afternoon. The observed features of the PWV diurnal cycle are explained in a qualitative way on the basis of the air temperature, the transport of moisture by local winds, and the turbulent vertical mixing.

  13. Annual Climatology of the Diurnal Cycle on the Canadian Prairies

    NASA Astrophysics Data System (ADS)

    Betts, Alan; Tawfik, Ahmed

    2016-01-01

    We show the annual climatology of the diurnal cycle, stratified by opaque cloud, using the full hourly resolution of the Canadian Prairie data. The opaque cloud field itself has distinct cold and warm season diurnal climatologies; with a near-sunrise peak of cloud in the cold season and an early afternoon peak in the warm season. There are two primary climate states on the Canadian Prairies, separated by the freezing point of water, because a reflective surface snow cover acts as a climate switch. Both cold and warm season climatologies can be seen in the transition months of November, March and April with a large difference in mean temperature. In the cold season with snow, the diurnal ranges of temperature and relative humidity increase quasi-linearly with decreasing cloud, and increase from December to March with increased solar forcing. The warm season months, April to September, show a homogeneous coupling to the cloud cover, and a diurnal cycle of temperature and humidity that depends only on net longwave. Our improved representation of the diurnal cycle shows that the warm season coupling between diurnal temperature range and net longwave is weakly quadratic through the origin, rather than the linear coupling shown in earlier papers. We calculate the conceptually important 24-h imbalances of temperature and relative humidity (and other thermodynamic variables) as a function of opaque cloud cover. In the warm season under nearly clear skies, there is a warming of +2oC and a drying of -6% over the 24-h cycle, which is about 12% of their diurnal ranges. We summarize results on conserved variable diagrams and explore the impact of surface windspeed on the diurnal cycle in the cold and warm seasons. In all months, the fall in minimum temperature is reduced with increasing windspeed, which reduces the diurnal temperature range. In July and August, there is an increase of afternoon maximum temperature and humidity at low windspeeds, and a corresponding rise in

  14. Hypothalamic-pituitary-adrenal (HPA) axis function in the California mouse (Peromyscus californicus): Changes in baseline activity, reactivity, and fecal excretion of glucocorticoids across the diurnal cycle

    PubMed Central

    Harris, Breanna N.; Saltzman, Wendy; de Jong, Trynke R.; Milnes, Matthew R.

    2012-01-01

    The California mouse, Peromyscus californicus, is an increasingly popular animal model in behavioral, neural, and endocrine studies, but little is known about its baseline hypothalamicpituitary-adrenal (HPA) axis activity or HPA responses to stressors. We characterized plasma corticosterone (CORT) concentrations in P. californicus under baseline conditions across the diurnal cycle, in response to pharmacological manipulation of the HPA axis, and in response to a variety of stressors at different times of day. In addition, we explored the use of fecal samples to monitor adrenocortical activity non-invasively. California mice have very high baseline levels of circulating CORT that change markedly over 24 hours, but that do not differ between the sexes. This species may be somewhat glucocorticoid-resistant in comparison to other rodents as a relatively high dose of dexamethasone (5 mg/kg, s.c.) was required to suppress plasma CORT for 8 h post-injection. CORT responses to stressors and ACTH injection differed with time of day, as CORT concentrations were elevated more readily during the morning (inactive period) than in the evening (active period) when compared to time-matched control. Data from 3H-CORT injection studies show that the time course for excretion of fecal CORT, or glucocorticoid metabolites, differs with time of injection. Mice injected in the evening excreted the majority of fecal radioactivity 2–4 h post-injection whereas mice injected during the morning did so at 14–16 h post-injection. Unfortunately, the antibody we used does not adequately bind the most prevalent fecal glucocorticoid metabolites and therefore we could not validate its use for fecal assays. PMID:23026495

  15. Dissociation between diurnal cycles in locomotor activity, feeding behavior and hepatic PERIOD2 expression in chronic alcohol-fed mice.

    PubMed

    Zhou, Peng; Werner, John H; Lee, Donghoon; Sheppard, Aaron D; Liangpunsakul, Suthat; Duffield, Giles E

    2015-06-01

    Chronic alcohol consumption contributes to fatty liver disease. Our studies revealed that the hepatic circadian clock is disturbed in alcohol-induced hepatic steatosis, and effects of chronic alcohol administration upon the clock itself may contribute to steatosis. We extended these findings to explore the effects of chronic alcohol treatment on daily feeding and locomotor activity patterns. Mice were chronically pair-fed ad libitum for 4 weeks using the Lieber-DeCarli liquid diet, with calorie-controlled liquid and standard chow diets as control groups. Locomotor activity, feeding activity, and real-time bioluminescence recording of PERIOD2::LUCIFERASE expression in tissue explants were measured. Mice on liquid control and chow diets exhibited normal profiles of locomotor activity, with a ratio of 22:78% day/night activity and a peak during early night. This pattern was dramatically altered in alcohol-fed mice, marked by a 49:51% ratio and the absence of a distinct peak. While chow-diet fed mice had a normal 24:76% ratio of feeding activity, with a peak in the early night, this pattern was dramatically altered in both liquid-diet groups: mice had a 43:57% ratio, and an absence of a distinct peak. Temporal differences were also observed between the two liquid-diet groups during late day. Cosinor analysis revealed a ∼4-h and ∼6-h shift in the alcohol-fed group feeding and locomotor activity rhythms, respectively. Analysis of hepatic PER2 expression revealed that the molecular clock in alcohol-fed and control liquid-diet mice was shifted by ∼11 h and ∼6 h, respectively. No differences were observed in suprachiasmatic nucleus explants, suggesting that changes in circadian phase in the liver were generated independently from the central clock. These results suggest that chronic alcohol consumption and a liquid diet can differentially modulate the daily rhythmicity of locomotor and feeding behaviors, aspects that might contribute to disturbances in the circadian

  16. Dissociation between diurnal cycles in locomotor activity, feeding behavior and hepatic PERIOD2 expression in chronic alcohol-fed mice

    PubMed Central

    Zhou, Peng; Werner, John H.; Lee, Donghoon; Sheppard, Aaron D.; Liangpunsakul, Suthat; Duffield, Giles E.

    2015-01-01

    Chronic alcohol consumption contributes to fatty liver disease. Our studies revealed that the hepatic circadian clock is disturbed in alcohol-induced hepatic steatosis, and effects of chronic alcohol administration upon the clock itself may contribute to steatosis. We extended these findings to explore the effects of chronic alcohol treatment on daily feeding and locomotor activity patterns. Mice were chronically pair-fed ad libitum for 4 weeks using the Lieber-DeCarli liquid diet, with calorie-controlled liquid and standard chow diets as control groups. Locomotor activity, feeding activity, and real-time bioluminescence recording of PERIOD2::LUCIFERASE expression in tissue explants were measured. Mice on liquid control and chow diets exhibited normal profiles of locomotor activity, with a ratio of 22:78% day/night activity and a peak during early night. This pattern was dramatically altered in alcohol-fed mice, marked by a 49:51% ratio and the absence of a distinct peak. While chow-diet fed mice had a normal 24:76% ratio of feeding activity, with a peak in the early night, this pattern was dramatically altered in both liquid-diet groups: mice had a 43:57% ratio, and an absence of a distinct peak. Temporal differences were also observed between the two liquid-diet groups during late day. Cosinor analysis revealed a ~4-h and ~6-h shift in the alcohol-fed group feeding and locomotor activity rhythms, respectively. Analysis of hepatic PER2 expression revealed that the molecular clock in alcohol-fed and control liquid-diet mice was shifted by ~11 h and ~6 h, respectively. No differences were observed in suprachiasmatic nucleus explants, suggesting that changes in circadian phase in the liver were generated independently from the central clock. These results suggest that chronic alcohol consumption and a liquid diet can differentially modulate the daily rhythmicity of locomotor and feeding behaviors, aspects that might contribute to disturbances in the circadian timing

  17. Impacts of the diurnal cycle of solar radiation on spiral rainbands

    NASA Astrophysics Data System (ADS)

    Zhou, Shunwu; Ma, Yue; Ge, Xuyang

    2016-09-01

    Based on idealized numerical simulations, the impacts of the diurnal cycle of solar radiation on the diurnal variation of outer rainbands in a tropical cyclone are examined. It is found that cold pools associated with precipitation-driven downdrafts are essential for the growth and propagation of spiral rainbands. The downdrafts result in surface outflows, which act as a lifting mechanism to trigger the convection cell along the leading edge of the cold pools. The diurnal cycle of solar radiation may modulate the diurnal behavior of the spiral rainbands. In the daytime, shortwave radiation will suppress the outer convection and thus weaken the cold pools. Meanwhile, the limited cold pool activity leads to a strong modification of the moisture field, which in turn inhibits further convection development.

  18. Phase reversal of the diurnal cycle in the midlatitude ionosphere

    NASA Astrophysics Data System (ADS)

    Liu, Huixin; Thampi, Smitha V.; Yamamoto, Mamoru

    The typical diurnal cycle of the midlatitude F region electron density consists of a midday maximum and a midnight minimum. However, a phase reversal of this diurnal cycle has been found to occur in three distinct regions on the globe. They are the East Asian (EA) region centered around (53N, 150E), the Northern Atlantic (NA) region centered around (45N, 50W) and the South Pacific (SP) region centered around (60S, 110W). The intensively reported Wed-dell Sea Anomaly falls inside the SP region. The phase reversal occurs during March-August in EA and NA regions, and between August and March in SP region, being most prominent in local summer. Furthermore, this diurnal anomaly is more pronounced at solar minimum than at solar maximum, and more pronounced in SP region than in NA and EA regions, in terms of larger diurnal magnitude and more months it lasts in a year. It is emphasized that the diurnal anomaly consists of not only a nighttime enhancement, but also a concurrent noontime depletion. Hence, midlatitude summer nighttime enhancements reported in previous studies are just part of this reversed diurnal cycle. The cause for the phase reversal involves several interplaying physical processes. Among these, the neutral wind combined with the geomagnetic field configuration plays a pivotal role. It generates a onewave longitudinal pattern at south-ern middle latitudes and a twowave pattern at northern middle latitudes, whose wave peaks correspond to the center of the SP, EA, and NA regions, respectively. The seasonal variation of neutral winds and downward motion of the ionization induced by thermal contraction of the ionosphere at sunset may largely control the occurring local time of the nighttime density enhancement and how long it persists in different months. The phase reversal occurs as a result of close ionneutral coupling. It is further noted that winter anomaly in the EA, NA, and SP regions is very weak or missing.

  19. Assimilating Satellite SST Observations into a Diurnal Cycle Model

    NASA Astrophysics Data System (ADS)

    Pimentel, S.; Haines, K.; Nichols, N. K.

    2006-12-01

    The wealth of satellite sea surface temperature (SST) data now available opens the possibility of large improvements in SST estimation. However the use of such data is not straight forward; a major difficulty in assimilating satellite observations is that they represent a near surface temperature, whereas in ocean models the top level represents the temperature at a greater depth. During the day, under favourable conditions of clear skies and calm winds, the near surface temperature is often seen to have a diurnal cycle that is picked up in satellite observations. Current ocean models do not have the vertical or temporal resolution to adequately represent this daytime warming. The usual approach is to discard daytime observations as they are considered diurnally `corrupted'. A new assimilation technique is developed here that assimilates observations into a diurnal cycle model. The diurnal cycle of SSTs are modelled using a 1-D mixed layer model with fine near surface resolution and 6 hourly forcing from NWP analyses. The accuracy of the SST estimates are hampered by uncertainties in the forcing data. The extent of diurnal SST warming at a particular location and time is predominately governed by a non-linear response to cloud cover and sea surface wind speeds which greatly affect the air-sea fluxes. The method proposed here combines infrared and microwave SST satellite observations in order to derive corrections to the cloud cover and wind speed values over the day. By adjusting the forcing, SST estimation and air-sea fluxes should be improved and are at least more consistent with each other. This new technique for assimilating SST data can be considered a tool for producing more accurate diurnal warming estimates.

  20. Diurnal cycle of convection during the CAIPEEX 2011 experiment

    NASA Astrophysics Data System (ADS)

    Resmi, EA; Malap, Neelam; Kulkarni, Gayatri; Murugavel, P.; Nair, Sathy; Burger, Roelof; Prabha, Thara V.

    2015-08-01

    The diurnal cycle of convective storm events is investigated in the study with the help of C-band radar reflectivity data during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX 2011) in combination with other ground-based observations. A threshold reflectivity of 25 dBZ is used to identify the initiation of storms. Observations from collocated sensors such as a microwave radiometer profiler, water vapor measurement from eddy covariance system, and wind lidar measurements are used to investigate the characteristic features and diurnal cycle of convectively initiated storms from 21st September to 5th November 2011. The maximum reflectivity follows a normal distribution with a mean value of 40 dBZ. The cloud depth over the domain varied between 5 and 15 km corresponding to a range of reflectivity of 30-50 dBZ values. In the diurnal cycle, double maximum in the precipitation flux is noted—one during the afternoon hours associated with the diurnal heating and the other in the nocturnal periods. The nocturnal precipitation maximum is attributed to initiation of several single-cell storms (of congestus type) with a duration that is larger than the storms initiated during the daytime. The convective available potential energy (CAPE) showed a diurnal variation and was directly linked with the surface level water vapor content. The high CAPE favored single storms with a reflectivity >40 dBZ and higher echo top heights. In the evening or late night hours, a nocturnal low-level jet present over the location together with the reduced stability above the cloud base favored enhancement of low-level moisture, CAPE, and further initiation of new convection. The study illustrated how collocated observations could be used to study storm initiation and associated thermodynamic features.

  1. Diurnal Cycles in Water Quality Across the Periodic Table

    NASA Astrophysics Data System (ADS)

    Kirchner, J. W.

    2013-12-01

    Diurnal cycles in water quality can provide important clues to the processes that regulate aquatic chemistry, but they often are masked by longer-term, larger-amplitude variability, making their detection and quantification difficult. Here I outline several methods that can detect diurnal cycles even when they are massively obscured by statistically ill-behaved noise. I demonstrate these methods using high-frequency water quality data from the Plylimon catchment in mid-Wales (Neal et al., 2013; Kirchner and Neal, 2013). Several aspects combine to make the Plynlimon data set unique worldwide. Collected at 7-hour intervals, the Plynlimon data set is much more densely sampled than typical long-term weekly or monthly water quality data. This 7-hour sampling was also continued for two years, much longer than typical intensive sampling campaigns, and the resulting time series encompass a wide range of climatic and hydrological conditions. Furthermore, each sample was analyzed for a wide range of solutes with diverse sources in the natural environment. However, the 7-hour sampling frequency is both coarse and irregular in comparison to diurnal cycles, making their detection and quantification difficult. Nonetheless, the methods outlined here enable detection of statistically significant diurnal cycles in over 30 solutes at Plynlimon, including alkali metals (Li, Na, K, Rb, and Cs), alkaline earths (Be, Mg, Ca, Sr, and Ba), transition metals (Al, Ti, Mn, Fe, Co, Ni, Zn, Mo, Cd, and Pb), nonmetals (B, NO3, Si, As, and Se), lanthanides and actinides (La, Ce, Pr, and U), as well as total dissolved nitrogen (TDN), dissolved organic carbon (DOC), Gran alkalinity, pH, and electrical conductivity. These solutes span every row of the periodic table, and more than six orders of magnitude in concentration. Many of these diurnal cycles are subtle, representing only a few percent, at most, of the total variance in the concentration time series. Nonetheless they are diagnostically

  2. Diurnal cycle on the Caribbean slope of Costa Rica: An observational study

    NASA Astrophysics Data System (ADS)

    Amador, J. A.; Saenz, F.

    2013-05-01

    The atmospheric diurnal cycle in tropical regions under different atmospheric environments is crucial to understand the role of convective activity (both, thermal and mechanical) in the global circulation energy budget. Many of the physical mechanisms involved in the diurnal cycle, such as the land-sea and mountain-valley breezes, are not well understood, partly because of lack of observational studies and the deficiencies shown by numerical models to capture the essence of the process. Studies of the diurnal cycle, and its interaction with other processes at different time and space scales, such as trade winds, have been relatively scarce. In this paper, preliminary results are presented for available observational data of precipitation and wind from several automatic meteorological stations in order to identify major features of the mean diurnal cycle on the Caribbean slope of Costa Rica. The analyzed region includes a relatively flat area near the coast and a mountain range to its west, being partly influenced by the trade wind system all year round. This factor provides the opportunity to investigate the diurnal cycle under different synoptic and climate conditions. Data consists of a set of 19 stations with hourly resolution for 2006-2011and 8 stations for 2000-2006. The spatial distribution of the stations covers a transect of about 350 km long, which allows a wide range of topographical conditions to be considered. Observational results over the region show a large contrast among the stations in the mean precipitation diurnal cycle patterns that seem to be the result of the interaction of the large scale environment (trades), the local land-sea characteristics, and the topography.

  3. Phase reversal of the diurnal cycle in the midlatitude ionosphere

    NASA Astrophysics Data System (ADS)

    Liu, Huixin; Thampi, Smitha V.; Yamamoto, Mamoru

    2010-01-01

    The typical diurnal cycle of the midlatitude F region electron density consists of a midday maximum and a midnight minimum. However, a phase reversal of this diurnal cycle has been found to occur in three distinct regions on the globe. They are the East Asian (EA) region centered around (53°N, 150°E), the Northern Atlantic (NA) region centered around (45°N, 50°W) and the South Pacific (SP) region centered around (60°S, 110°W). The intensively reported Weddell Sea Anomaly falls inside the SP region. The phase reversal occurs during March-August in EA and NA regions, and between August and March in SP region, being most prominent in local summer. Furthermore, this diurnal anomaly is more pronounced at solar minimum than at solar maximum, and more pronounced in SP region than in NA and EA regions, in terms of larger diurnal magnitude and more months it lasts in a year. It is emphasized that the diurnal anomaly consists of not only a nighttime enhancement, but also a concurrent noontime depletion. Hence, midlatitude summer nighttime enhancements reported in previous studies are just part of this reversed diurnal cycle. The cause for the phase reversal involves several interplaying physical processes. Among these, the neutral wind combined with the geomagnetic field configuration plays a pivotal role. It generates a one-wave longitudinal pattern at southern middle latitudes and a two-wave pattern at northern middle latitudes, whose wave peaks correspond to the center of the SP, EA, and NA regions, respectively. The seasonal variation of neutral winds and downward motion of the ionization induced by thermal contraction of the ionosphere at sunset may largely control the occurring local time of the nighttime density enhancement and how long it persists in different months. The phase reversal occurs as a result of close ion-neutral coupling. It is further noted that winter anomaly in the EA, NA, and SP regions is very weak or missing.

  4. Solar cycle and diurnal dependence of auroral structures

    NASA Astrophysics Data System (ADS)

    Partamies, N.; Whiter, D.; Syrjäsuo, M.; Kauristie, K.

    2014-10-01

    In order to facilitate usage of optical data in space climate studies, we have developed an automated algorithm to quantify the complexity of auroral structures as they appear in ground-based all-sky images. The image analysis is based on a computationally determined "arciness" value, which describes how arc like the auroral structures in the image are. With this new automatic method we have analyzed the type of aurora in about 1 million images of green aurora (λ = 557.7nm) captured at five camera stations in Finnish and Swedish Lapland in 1996-2007. We found that highly arc like structures can be observed in any time sector and their portion of the auroral structures varies much less than the fraction of more complex forms. The diurnal distribution of arciness is in agreement with an earlier study with high arc occurrence rate in the evening hours and steadily decreasing toward the late morning hours. The evolution of less arc-like auroral structures is more dependent on the level of geomagnetic activity and solar cycle than the occurrence of arcs. The median arciness is higher during the years close to the solar minimum than during the rest of the solar cycle. Unlike earlier proposed, the occurrence rate of both arcs and more complex auroral structures increases toward the solar maximum and decreases toward the solar minimum. The cyclic behavior of auroral structures seen in our data is much more systematic and clear than previously reported visual studies suggest. The continuous arciness index describing the complexity of auroral structures can improve our understanding on auroral morphology beyond the few commonly accepted structure classes, such as arcs, patches, and omega bands. Arciness can further be used to study the relationship of auroral structures at different complexity levels and magnetospheric dynamics.

  5. Diurnal cycles in water quality across the periodic table

    NASA Astrophysics Data System (ADS)

    Kirchner, James

    2014-05-01

    Diurnal cycles in water quality can provide important clues to the processes that regulate aquatic chemistry, but they often are masked by longer-term, larger-amplitude variability, making their detection and quantification difficult. Here I outline methods that can detect diurnal cycles even when they are massively obscured by statistically ill-behaved noise. I demonstrate these methods using high-frequency water quality data from the Plylimon catchment in mid-Wales (Neal et al., 2013; Kirchner and Neal, 2013). Several aspects combine to make the Plynlimon data set unique worldwide. Collected at 7-hour intervals, the Plynlimon data set is much more densely sampled than typical long-term weekly or monthly water quality data. This 7-hour sampling was also continued for two years, much longer than typical intensive sampling campaigns, and the resulting time series encompass a wide range of climatic and hydrological conditions. Furthermore, each sample was analyzed for a wide range of solutes with diverse sources in the natural environment. However, the 7-hour sampling frequency is both coarse and irregular in comparison to diurnal cycles, making their detection and quantification difficult. Nonetheless, the methods outlined here enable detection of statistically significant diurnal cycles in over 30 solutes at Plynlimon, including alkali metals (Li, Na, K, Rb, and Cs), alkaline earths (Be, Mg, Ca, Sr, and Ba), transition metals (Al, Ti, Mn, Fe, Co, Ni, Zn, Mo, Cd, and Pb), nonmetals (B, NO3, Si, As, and Se), lanthanides and actinides (La, Ce, Pr, and U), as well as total dissolved nitrogen (TDN), dissolved organic carbon (DOC), Gran alkalinity, pH, and electrical conductivity. These solutes span every row of the periodic table, and more than six orders of magnitude in concentration. Many of these diurnal cycles are subtle, representing only a few percent, at most, of the total variance in the concentration time series. Nonetheless they are diagnostically useful

  6. Scale interaction between the MJO and the diurnal cycle of precipitation over the Maritime Continent

    NASA Astrophysics Data System (ADS)

    Peatman, Simon; Matthews, Adrian; Stevens, David

    2013-04-01

    The Maritime Continent is a highly-populated region of many islands and shallow oceans, located in the oceanic warm pool, between the Indian and Pacific Oceans. A strong diurnal cycle of precipitation exists due to onshore breezes causing strong convergence of moist air - enhanced by topographic effects - over the land during the day time, peaking during afternoon-evening. The respective diurnal cycle over the ocean is far weaker and does not peak until early in the morning. On intra-seasonal time-scales the greatest source of variability in the tropics is the Madden-Julian Oscillation (MJO). The convectively active part of the MJO propagates slowly (~5 ms-1) eastward through the warm pool from the Indian Ocean to the western Pacific, followed by the convectively suppressed part. The complex topography of the Maritime Continent means the exact nature of the propagation through this region is unclear. Model simulations of the MJO are often poor over the region, leading to errors in latent heat release and, subsequently, global errors in medium-range weather prediction and climate simulation. Using 14 northern hemisphere winters of high-resolution satellite data it is shown that, over regions where the diurnal cycle is strong, more than 80% of the variance in precipitation during an MJO cycle is accounted for by changes in the amplitude of the diurnal cycle. A canonical view of the MJO is of smooth eastward progression of a large-scale precipitation envelope over the warm pool. However, by computing "MJO harmonics" it is shown that the leading edge of the precipitation envelope advances over the islands of the Maritime Continent approximately 6 days or 2000 km ahead of the main body. This behaviour can be accommodated within existing theories of MJO propagation. When the active convective MJO envelope is over the eastern Indian Ocean, frictional moisture convergence and topographic blocking in the easterlies of the equatorial Kelvin wave response supply moisture to

  7. Seasonal variations in the lightning diurnal cycle and implications for the global electric circuit

    NASA Astrophysics Data System (ADS)

    Blakeslee, Richard J.; Mach, Douglas M.; Bateman, Monte G.; Bailey, Jeffrey C.

    2014-01-01

    Data obtained from the Optical Transient Detector and the Lightning Imaging Sensor satellites (70° and 35° inclination low earth orbits, respectively) are used to statistically determine the number of flashes in the seasonal diurnal cycle as a function of local and universal time. These data include corrections for detection efficiency and instrument view time. They are further subdivided by season, land versus ocean, and other spatial (e.g., continents) and temporal (e.g., time of peak diurnal amplitude) categories. These statistics are then combined with analyses of high altitude aircraft observations of electrified clouds to produce the seasonal diurnal variation in the global electric circuit. Continental results display strong diurnal variation, with a lightning peak in the late afternoon and a minimum in late morning. In geographical regions dominated by large mesoscale convective systems, the peak in the diurnal curve shifts toward late evening or early morning hours. The maximum seasonal diurnal flash rate occurs in June-August, corresponding to the Northern Hemisphere summer, while the minimum occurs in December-February. Summer lightning dominates over winter activity and springtime lightning dominates over fall activity at most continental locations. Oceanic lightning exhibits minimal diurnal variation, but morning hours are slightly enhanced over afternoon. As was found earlier, for the annual diurnal variation, using basic assumptions about the mean storm currents as a function of flash rate and location (i.e., land/ocean), our seasonal estimates of the current in the global electric circuit provide an excellent match with independent measurements of the seasonal Carnegie curve diurnal variations. The maximum (minimum) total mean current of 2.4 kA (1.7 kA) is found during Northern Hemisphere summer (winter). Land thunderstorms supply about one half (52%) of the total global current. Ocean thunderstorms contribute about one third (31%) and the non

  8. New fire diurnal cycle characterizations to improve fire radiative energy assessments made from low-Earth orbit satellites sampling

    NASA Astrophysics Data System (ADS)

    Andela, N.; Kaiser, J. W.; van der Werf, G. R.; Wooster, M. J.

    2015-03-01

    Accurate near real time fire emissions estimates are required for air quality forecasts. To date, most approaches are based on satellite-derived estimates of fire radiative power (FRP), which can be converted to fire radiative energy (FRE) which is directly related to fire emissions. Uncertainties in these FRE estimations are often substantial. This is for a large part because the most often used low-Earth orbit satellite-based instruments like the MODerate-resolution Imaging Spectroradiometer (MODIS) have a relatively poor sampling of the usually pronounced fire diurnal cycle. In this paper we explore the spatial variation of this fire diurnal cycle and its drivers. Specifically, we assess how representing the fire diurnal cycle affects FRP and FRE estimations when using data collected at MODIS overpasses. Using data assimilation we explored three different methods to estimate hourly FRE, based on an incremental sophistication of parameterizing the fire diurnal cycle. We sampled data from the geostationary Meteosat Spinning Enhanced Visible and Infrared Imager (SEVIRI) at MODIS detection opportunities to drive the three approaches. The full SEVIRI time-series, providing full coverage of the diurnal cycle, were used to evaluate the results. Our study period comprised three years (2010-2012), and we focussed on Africa and the Mediterranean basin to avoid the use of potentially lower quality SEVIRI data obtained at very far off-nadir view angles. We found that the fire diurnal cycle varies substantially over the study region, and depends on both fuel and weather conditions. For example, more "intense" fires characterized by a fire diurnal cycle with high peak fire activity, long duration over the day, and with nighttime fire activity are most common in areas of large fire size (i.e., large burned area per fire event). These areas are most prevalent in relatively arid regions. Ignoring the fire diurnal cycle as done currently in some approaches caused structural

  9. Cycle-to-Cycle Variations in the Diurnal Variation of Galactic Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Thomas, Simon; Owen, Chris; Owens, Matt; Lockwood, Mike

    2016-04-01

    We examine mean profiles of the diurnal variations in galactic cosmic ray flux using a number of neutron monitors at different magnetic latitudes and longitudes. By splitting all of the hourly neutron monitor data by the solar magnetic polarity and analysing the mean normalised neutron monitor count rates between these, we see that the diurnal variation changes phase by 1-2 hours between the two polarity states for the majority of non-polar neutron monitors. The intensity and variability of a heliospheric magnetic field is analysed for every day and found not to be the cause of the phase change. Some polar neutron monitors, however, show different, smaller amplitude variations in phase between polarity cycles. Time series of the time of the maximum in the diurnal variation are presented between 1965 and 2013. Our results agree with previous work by confirming the presence of a 22-year variation in the peak time of the diurnal variation and a 11-year variation in the amplitude, but also show that not all neutron monitors show the same trend. An analysis of the magnetic latitude dependence of the diurnal variation shows that the time-of-day of the peak and trough of this variation gives opposing changes to the amplitude of the 22-year change. We suggest that this could be due to changes in the configeration of the heliospheric magnetic field for consecutive cycles.

  10. Spatiotemporal Variation of Diurnal Cycle under the Different MJO Phases

    NASA Astrophysics Data System (ADS)

    Yoneyama, K.

    2013-12-01

    During a two-month special observing period (October - November 2011) of the MJO field campaign, which composed of several projects of CINDY2011, DYNAMO, AMIE, and LASP, two MJO events were captured by the intensive (3-hourly) sounding array deployed over the central Indian Ocean. While the upward moistening was confirmed before the onset of these events, both cases were identified as an MJO event after the cloud systems reached over the central Indian Ocean from the Inter-tropical Convergence Zone in the Southern Hemisphere. While this feature suggests the lateral transport of moist air, dry intrusion into the equatorial region in the lower/mid-troposphere was also observed. The relationship among these features are not well understood. In the previous studies related to the recharge process under the suppressed condition with dry air aloft, diurnal cycle was a key to moisten the dry atmosphere above. Thus, as a first step to understand their relationship as well as a role for the initiation process of the MJO convection over the equatorial region, vertical features obtained by the radiosonde sounding at the southern array were examined with focus of diurnal cycle as a basic variation by referring the MJO phase defined by Wheeler and Hendon's method. Basically, stable layers near 0 C (~550 hPa) and trade inversion (800~750 hPa) became dominant over the equatorial sites after the MJO convective center moved east (Phases 4-7). During the pre-onset and onset period (Phases 2-3), lower troposphere (~970 hPa) became more unstable in nighttime (18-04 LT) and moist air region extended to upward from early morning (03-06 LT, ~700 hPa) to mid-troposphere in daytime (12-18 LT, 500~300 hPa). Stable layers near the trade inversion and 0 C rather appear accompanied with convections (i.e. convection might produce or contribute those stable layers).

  11. Cumulus moistening, the diurnal cycle, and large-scale tropical dynamics

    NASA Astrophysics Data System (ADS)

    Ruppert, James H., Jr.

    Observations and modeling techniques are employed to diagnose the importance of the diurnal cycle in large-scale tropical climate. In the first part of the study, soundings, radar, and surface flux measurements collected in the Indian Ocean DYNAMO experiment (Dynamics of the Madden--Julian Oscillation, or MJO) are employed to study MJO convective onset. According to these observations, MJO onset takes place as follows: moistening of the low--midtroposphere is accomplished by cumuliform clouds that deepen as the drying by large-scale subsidence and horizontal advection simultaneously wane. This relaxing of subsidence is tied to decreasing column radiative cooling, which links back to the evolving cloud population. A new finding from these observations is the high degree to which the diurnal cycle linked to air-sea and radiative fluxes invigorates clouds and drives column moistening each day. This diurnally modulated cloud field exhibits pronounced mesoscale organization in the form of open cells and horizontal convective rolls. Based on these findings, it is hypothesized that the diurnal cycle and mesoscale cloud organization represent two manners in which local convective processes promote more vigorous day-to-day tropospheric moistening than would otherwise occur. A suite of model tests are carried out in the second part of the study to 1) test the hypothesis that the diurnal cycle drives moistening on longer timescales, and 2) better understand the relative roles of diurnally varying sea surface temperature (SST) and direct atmospheric radiative heating in the diurnal cycle of convection. Moist convection is explicitly represented in the model, the diurnal cycle of SST is prescribed, and cloud-interactive radiation is simulated with a diurnal cycle in shortwave heating. The large-scale dynamics are parameterized using the spectral weak temperature gradient (WTG) technique recently introduced by Herman and Raymond. In this scheme, external (i.e., large

  12. Diurnal cycle of the Oklahoma City urban heat island

    NASA Astrophysics Data System (ADS)

    Basara, Jeffrey B.; Hall, Peter K.; Schroeder, Amanda J.; Illston, Bradley G.; Nemunaitis, Kodi L.

    2008-10-01

    Between the dates of 28 June and 31 July 2003, the Joint Urban 2003 (JU2003) field project was conducted in Oklahoma City and was the largest urban dispersion experiment ever in North America. Because the focus of JU2003 was on atmospheric processes within the urban environment, an extremely dense network of instrumentation was deployed in and around the central business district (CBD) both prior to and during the field experiment. Among the variables collected were high-resolution observations of air temperature from various instrument sources. Additional observations of air temperature were also collected at Oklahoma Mesonet stations in the rural areas surrounding Oklahoma City. Using an index value, the diurnal cycle of the urban heat island (UHI) for Oklahoma City, with respect to the surrounding rural terrain, was quantified. The results revealed a consistent mean nocturnal UHI greater than 1.5°C at both 2 and 9 m. However, observations at 2 m during JU2003 revealed a significant urban "cool" island during the convective portion of the day. The mean variability of temperature within the urban core of Oklahoma City increased significantly after sunrise, increased to a maximum near solar noon, and decreased following sunset. These results were inconsistent with the rural observations wherein the variability among sites was maximized during the nocturnal period. Finally, the vertical temperature gradient between 2 and 9 m demonstrated a clear and strong diurnal trend at the rural locations, whereas observations from the urban environment were nearly isothermal and consistent with near-neutral conditions throughout JU2003.

  13. The diurnal and solar cycle variation of the charge exchange induced hydrogen escape flux

    NASA Technical Reports Server (NTRS)

    Maher, L. J.; Tinsley, B. A.

    1978-01-01

    On the basis of ion temperature and density data at specific points and times in June 1969 provided by the OGO 6 satellite, and altitude profiles of the ion and electron temperature and concentration provided by the Arecibo radar facility over the period February 1972-April 1974, the diurnal and solar cycle variation of the charge-exchange-induced hydrogen escape flux was investigated. It was calculated that for low to moderate solar activity at Arecibo, the diurnal ratio of the maximum-to-minimum charge-exchange-induced hydrogen escape flux was approximately 6 with a peak around noon and a minimum somewhere between 0100 and 0300 h LT. This study of a limited amount of OGO 6 and Arecibo data seems to indicate that the charge-exchange-induced hydrogen escape flux increases as the F(10.7) flux increases for low to moderate solar activity.

  14. Diurnal patterns in lightning activity over South America

    NASA Astrophysics Data System (ADS)

    Ávila, Eldo E.; Bürgesser, Rodrigo E.; Castellano, Nesvit E.; Nicora, M. Gabriela

    2015-04-01

    Satellite observations of lightning flash distribution data are used to examine the diurnal cycle of lightning activity over the tropical and subtropical regions of South America. A harmonic analysis is used to study the spatial variations in the peak and strength of diurnal lightning activity across this area. Results show that in the northern and central regions of South America, the times of maxima in lightning activity was concentrated from late afternoon to evening hours (between 14:00 and 18:00 local time), which may be associated with the peaking of the local convective activity connected with heating of the surface caused by daytime insolation. In subtropical South America, particularly in the area limited by 25°S, 35°S of latitude and 70°W, 50°W of longitude, the time of maximum lightning activity was shifted to nocturnal hours, extending from close to midnight to early morning hours. This behavior can be associated to the peak in mesoscale convective systems in the region which occurs in the morning hours. The annual flash densities in the tropical and subtropical parts of the continent were found to have comparable magnitudes. However, the contribution of the continental tropics to the global electric circuit dominates over the continental subtropics contribution throughout all seasons, since the surface covered by the tropical region is more than twice the area covered by the subtropical region.

  15. Spatial patterns in timing of the diurnal temperature cycle

    NASA Astrophysics Data System (ADS)

    Holmes, T. R. H.; Crow, W. T.; Hain, C.

    2013-05-01

    This paper investigates the structural difference in timing of the diurnal temperature cycle (DTC) over land resulting from choice of measuring device or model framework. It is shown that the timing can be reliably estimated from temporally sparse observations acquired from a constellation of low Earth orbiting satellites given record lengths of at least three months. Based on a year of data, the spatial patterns of mean DTC timing are compared between Ka-band temperature estimates, geostationary thermal infrared (TIR) temperature estimates and numerical weather prediction model output from the Global Modeling and Assimilation Office (GMAO). It is found that the spatial patterns can be explained by vegetation effects, sensing depth differences and more speculatively the orientation of orographic relief features. In absolute terms, the GMAO model puts the peak of the DTC on average at 12:50 local solar time, 23 min before TIR with a peak temperature at 13:13. Since TIR is the shallowest observation of the land surface, this small difference represents a structural error that possibly affects the models ability to assimilate observations that are closely tied to the DTC. For non-desert areas, the Ka-band observations have only a small delay of about 15 min with the TIR observations which is in agreement with their respective theoretical sensing depth. The results of this comparison provide insights into the structural differences between temperature measurements and models, and can be used as a first step to account for these differences in a coherent way.

  16. The Diurnal Cycle in TOGA-COARE: Regional Scale Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Jia, Y.; Wang, Y.; Sui, C.-H.

    1999-01-01

    The diurnal variation of precipitation processes over the tropics is a well-known phenomenon and has been studied using surface rainfall data, radar reflectivity data, and satellite-derived cloudiness and precipitation. Recently, Sui (1997) analyzed observations from TOGA COARE in the tropical western Pacific ocean to study the relevant mechanisms producing diurnal variation of precipitation. They found that the diurnal SST cycle is important for afternoon showers in the undisturbed periods and diurnal radiative processes for nocturnal rainfall. Takayabu (1996) found a quasi-2-day cycle in precipitation during TOGA COARE and they suggested that inertia-gravity waves may be associated with this 2-day cycle. Chen and Houze (1997), however, suggested that the quasi-2-day oscillation is mainly a function of the time required by the lower-tropospheric moisture field to recover from the drying caused by deep convection. In this study, the Penn State/NCAR Mesoscale Model (MM5) with improved physics (i.e., cloud microphysics, radiation, land-soil-vegetation-surface processes, and TOGA COARE flux scheme) and a multiple level nesting technique will be used to simulate two TOGA COARE convective espisodes, one convectively suppressed phase (mid to late January 1993) and one convectively active phase (mid to late December 1992). We will examine precipitation processes over the open ocean and over land by comparing MM5 simulated rainfall and out-going longwave radiation. By examining the OLR and precipitation, we can determine if there is a temporal lag between the maximum precipitation and the coldest upwelling longwave radiation (the time-lag between stratiform-cirrus and convective towers). The boundary layer response by (or recovery from) precipitation processes will also be shown by examining the PBL thermodynamic structure and the sensible and latent heat fluxes. A preliminary MM5 simulation showed a clear diurnal variation in rainfall over both land and open ocean for the

  17. Covariability in the Monthly Mean Convective and Radiative Diurnal Cycles in the Amazon

    NASA Technical Reports Server (NTRS)

    Dodson, Jason B.; Taylor, Patrick C.

    2015-01-01

    The diurnal cycle of convective clouds greatly influences the radiative energy balance in convectively active regions of Earth, through both direct presence, and the production of anvil and stratiform clouds. Previous studies show that the frequency and properties of convective clouds can vary on monthly timescales as a result of variability in the monthly mean atmospheric state. Furthermore, the radiative budget in convectively active regions also varies by up to 7 Wm-2 in convectively active regions. These facts suggest that convective clouds connect atmospheric state variability and radiation variability beyond clear sky effects alone. Previous research has identified monthly covariability between the diurnal cycle of CERES-observed top-of-atmosphere radiative fluxes and multiple atmospheric state variables from reanalysis over the Amazon region. ASVs that enhance (reduce) deep convection, such as CAPE (LTS), tend to shift the daily OLR and cloud albedo maxima earlier (later) in the day by 2-3 hr. We first test the analysis method using multiple reanalysis products for both the dry and wet seasons to further investigate the robustness of the preliminary results. We then use CloudSat data as an independent cloud observing system to further evaluate the relationships of cloud properties to variability in radiation and atmospheric states. While CERES can decompose OLR variability into clear sky and cloud effects, it cannot determine what variability in cloud properties lead to variability in the radiative cloud effects. Cloud frequency, cloud top height, and cloud microphysics all contribute to the cloud radiative effect, all of which are observable by CloudSat. In addition, CloudSat can also observe the presence and variability of deep convective cores responsible for the production of anvil clouds. We use these capabilities to determine the covariability of convective cloud properties and the radiative diurnal cycle.

  18. Spatial patterns in timing of the diurnal temperature cycle

    NASA Astrophysics Data System (ADS)

    Holmes, T. R. H.; Crow, W. T.; Hain, C.

    2013-10-01

    This paper investigates the structural difference in timing of the diurnal temperature cycle (DTC) over land resulting from choice of measuring device or model framework. It is shown that the timing can be reliably estimated from temporally sparse observations acquired from a constellation of low Earth-orbiting satellites given record lengths of at least three months. Based on a year of data, the spatial patterns of mean DTC timing are compared between temperature estimates from microwave Ka-band, geostationary thermal infrared (TIR), and numerical weather prediction model output from the Global Modeling and Assimilation Office (GMAO). It is found that the spatial patterns can be explained by vegetation effects, sensing depth differences and more speculatively the orientation of orographic relief features. In absolute terms, the GMAO model puts the peak of the DTC on average at 12:50 local solar time, 23 min before TIR with a peak temperature at 13:13 (both averaged over Africa and Europe). Since TIR is the shallowest observation of the land surface, this small difference represents a structural error that possibly affects the model's ability to assimilate observations that are closely tied to the DTC. The equivalent average timing for Ka-band is 13:44, which is influenced by the effect of increased sensing depth in desert areas. For non-desert areas, the Ka-band observations lag the TIR observations by only 15 min, which is in agreement with their respective theoretical sensing depth. The results of this comparison provide insights into the structural differences between temperature measurements and models, and can be used as a first step to account for these differences in a coherent way.

  19. Physiological and Transcriptional Responses of Anaerobic Chemostat Cultures of Saccharomyces cerevisiae Subjected to Diurnal Temperature Cycles

    PubMed Central

    Hebly, Marit; de Ridder, Dick; de Hulster, Erik A. F.; de la Torre Cortes, Pilar; Pronk, Jack T.

    2014-01-01

    Diurnal temperature cycling is an intrinsic characteristic of many exposed microbial ecosystems. However, its influence on yeast physiology and the yeast transcriptome has not been studied in detail. In this study, 24-h sinusoidal temperature cycles, oscillating between 12°C and 30°C, were imposed on anaerobic, glucose-limited chemostat cultures of Saccharomyces cerevisiae. After three diurnal temperature cycles (DTC), concentrations of glucose and extracellular metabolites as well as CO2 production rates showed regular, reproducible circadian rhythms. DTC also led to waves of transcriptional activation and repression, which involved one-sixth of the yeast genome. A substantial fraction of these DTC-responsive genes appeared to respond primarily to changes in the glucose concentration. Elimination of known glucose-responsive genes revealed an overrepresentation of previously identified temperature-responsive genes as well as genes involved in the cell cycle and de novo purine biosynthesis. In-depth analysis demonstrated that DTC led to a partial synchronization of the cell cycle of the yeast populations in chemostat cultures, which was lost upon release from DTC. Comparison of DTC results with data from steady-state cultures showed that the 24-h DTC was sufficiently slow to allow S. cerevisiae chemostat cultures to acclimate their transcriptome and physiology at the DTC temperature maximum and to approach acclimation at the DTC temperature minimum. Furthermore, this comparison and literature data on growth rate-dependent cell cycle phase distribution indicated that cell cycle synchronization was most likely an effect of imposed fluctuations of the relative growth rate (μ/μmax) rather than a direct effect of temperature. PMID:24814792

  20. Physiological and transcriptional responses of anaerobic chemostat cultures of Saccharomyces cerevisiae subjected to diurnal temperature cycles.

    PubMed

    Hebly, Marit; de Ridder, Dick; de Hulster, Erik A F; de la Torre Cortes, Pilar; Pronk, Jack T; Daran-Lapujade, Pascale

    2014-07-01

    Diurnal temperature cycling is an intrinsic characteristic of many exposed microbial ecosystems. However, its influence on yeast physiology and the yeast transcriptome has not been studied in detail. In this study, 24-h sinusoidal temperature cycles, oscillating between 12°C and 30°C, were imposed on anaerobic, glucose-limited chemostat cultures of Saccharomyces cerevisiae. After three diurnal temperature cycles (DTC), concentrations of glucose and extracellular metabolites as well as CO2 production rates showed regular, reproducible circadian rhythms. DTC also led to waves of transcriptional activation and repression, which involved one-sixth of the yeast genome. A substantial fraction of these DTC-responsive genes appeared to respond primarily to changes in the glucose concentration. Elimination of known glucose-responsive genes revealed an overrepresentation of previously identified temperature-responsive genes as well as genes involved in the cell cycle and de novo purine biosynthesis. In-depth analysis demonstrated that DTC led to a partial synchronization of the cell cycle of the yeast populations in chemostat cultures, which was lost upon release from DTC. Comparison of DTC results with data from steady-state cultures showed that the 24-h DTC was sufficiently slow to allow S. cerevisiae chemostat cultures to acclimate their transcriptome and physiology at the DTC temperature maximum and to approach acclimation at the DTC temperature minimum. Furthermore, this comparison and literature data on growth rate-dependent cell cycle phase distribution indicated that cell cycle synchronization was most likely an effect of imposed fluctuations of the relative growth rate (μ/μmax) rather than a direct effect of temperature. PMID:24814792

  1. Diurnal Cycles of Sulfate Reduction under Oxic Conditions in Cyanobacterial Mats

    PubMed Central

    Fründ, Claudia; Cohen, Yehuda

    1992-01-01

    Diurnal cycles of sulfate reduction were examined in a well-developed cyanobacterial mat which grew in an outdoor experimental hypersaline pond system at a constant salinity of 75 ± 5% for 3 years. Vertical profiles of sulfate reduction were determined for the upper 12 mm of the microbial mat. Sulfate reduction activities were compared with diurnal variations of oxygen and sulfide concentrations measured by microelectrodes. Significant activity of sulfate-reducing bacteria was detected under aerobic conditions during the daytime, with maximal activity at 2 p.m. When comparing sulfate reduction activities in sediment cores taken at 6 a.m. and 12 a.m. and incubated at a constant temperature in the light and in the dark, a distinct stimulation of the activity in the vertical profile of sulfate reduction by light was evident. It is therefore concluded that the maximal in situ activities, measured at 2 p.m. in the chemocline of the cyanobacterial mat, cannot be attributed to diurnal changes of temperature alone. The response of sulfate-reducing bacteria to the addition of specific carbon sources was significantly different in the cyanobacterial layer, the anoxygenic phototrophic bacterial layer, and the permanently reduced layer of the microbial mat. Sulfate reduction in the mat layer exposed to high oxygen concentrations as a result of cyanobacterial oxygenic photosynthesis was enhanced only by glycolate; in the microzone where the chemocline is found during the daytime, ethanol was the only carbon source to enhance sulfate reduction, while both ethanol and lactate enhanced this activity in the permanently reduced zone. PMID:16348641

  2. Rhythms of ghrelin, leptin, and sleep in rats: effects of the normal diurnal cycle, restricted feeding, and sleep deprivation.

    PubMed

    Bodosi, B; Gardi, J; Hajdu, I; Szentirmai, E; Obal, F; Krueger, J M

    2004-11-01

    To determine the relationships among plasma ghrelin and leptin concentrations and hypothalamic ghrelin contents, and sleep, cortical brain temperature (Tcrt), and feeding, we determined these parameters in rats in three experimental conditions: in free-feeding rats with normal diurnal rhythms, in rats with feeding restricted to the 12-h light period (RF), and in rats subjected to 5-h of sleep deprivation (SD) at the beginning of the light cycle. Plasma ghrelin and leptin displayed diurnal rhythms with the ghrelin peak preceding and the leptin peak following the major daily feeding peak in hour 1 after dark onset. RF reversed the diurnal rhythm of these hormones and the rhythm of rapid-eye-movement sleep (REMS) and significantly altered the rhythm of Tcrt. In contrast, the duration and intensity of non-REMS (NREMS) were hardly responsive to RF. SD failed to change leptin concentrations, but it promptly stimulated plasma ghrelin and induced eating. SD elicited biphasic variations in the hypothalamic ghrelin contents. SD increased plasma corticosterone, but corticosterone did not seem to influence either leptin or ghrelin. The results suggest a strong relationship between feeding and the diurnal rhythm of leptin and that feeding also fundamentally modulates the diurnal rhythm of ghrelin. The variations in hypothalamic ghrelin contents might be associated with sleep-wake activity in rats, but, unlike the previous observations in humans, obvious links could not be detected between sleep and the diurnal rhythms of plasma concentrations of either ghrelin or leptin in the rat. PMID:15475503

  3. Mesoscale Influences of Wind Farms Throughout a Diurnal Cycle

    NASA Astrophysics Data System (ADS)

    Fitch, A. C.; Lundquist, J. K.; Olson, J. B.

    2012-12-01

    Few observations are available to give insight into the interaction between large wind farms and the boundary layer. As wind farm deployment increases, questions are arising on the potential impact on meteorology within and downwind of large wind farms. While large-eddy simulation can provide insight into the detailed interaction between individual turbines and the boundary layer, to date it has been too computationally expensive to simulate wind farms with large numbers of turbines and the resulting wake far downstream. Mesoscale numerical weather prediction models provide the opportunity to investigate the flow in and around large wind farms as a whole, and the resulting impact on meteorology. To this end, we have implemented a wind farm parameterization in the Weather Research and Forecasting (WRF) model, which represents wind turbines by imposing a momentum sink on the mean flow; converting kinetic energy into electricity and turbulent kinetic energy (TKE). The parameterization improves upon previous models, basing the atmospheric drag of turbines on the thrust coefficient of a modern commercial turbine. In addition, the source of TKE varies with wind speed, reflecting the amount of energy extracted from the atmosphere by the turbines that does not produce electrical energy. We simulate a wind farm covering 10x10 km over land, consisting of 100 turbines each of nominal power output of 5 MW. Results will be presented showing how the wake structure varies dramatically over a diurnal cycle characteristic of a region in the Great Plains of the US, where wind farm deployment is planned. At night, a low-level jet forms within the rotor area, which is completely eliminated by energy extraction within the wind farm. The deep stable layer and lack of higher momentum air aloft at this time maximises the wind deficit and the length of the wake. The presentation will discuss the maximum reduction of wind speed within and downwind from the farm, and the wake e

  4. Linking diurnal cycles of river flow to interannual variations in climate

    USGS Publications Warehouse

    Lundquist, Jessica D.; Dettinger, Michael D.

    2003-01-01

    Many rivers in the Western United States have diurnal variations exceeding 10% of their mean flow in the spring and summer months. The shape and timing of the diurnal cycle is influenced by an interplay of the snow, topography, vegetation, and meteorology in a basin, and the measured result differs between wet and dry years. The largest interannual differences occur during the latter half of the melt season, as the snowline retreats to the highest elevations and most shaded slopes in a basin. In most basins, during this period, the hour of peak discharge shifts to later in the day, and the relative amplitude of the diurnal cycle decreases. The magnitude and rate of these changes in the diurnal cycle vary between years and may provide clues about how long- term hydroclimatic variations affect short-term basin dynamics.

  5. Diurnal cycle of precipitation in a global cloud-resolving model

    NASA Astrophysics Data System (ADS)

    Sato, T.; Miura, H.; Satoh, M.; Takayabu, Y. N.

    2008-12-01

    This study summarizes the diurnal cycle of precipitation that is simulated by a global cloud resolving model (GCRM) named NICAM (Nonhydrostatic ICosahedral Atmospheric Model) which does not use cumulus parameterizations due to high horizontal resolution. Thirty-day integration by NICAM successfully simulates precipitation diurnal cycle associated with land/sea breeze and thermally-induced topographic circulations as well as the horizontal propagation of diurnal cycle signals. A first harmonic of the diurnal cycle of precipitation in 7 km-mesh run agrees very well with the satellite observations in its geographical distributions although the amplitude is slightly overestimated and peak time is 1.5 hour later than that observed over land. Sensitivity experiments, changing the horizontal resolution, suggest that prominent resolution dependence is discernible in the precipitation diurnal cycle in NICAM. The coarser resolution (14 km mesh) run induces about three hour later peak than that in 7 km mesh run. The 3.5 km mesh run realistically produces peak time (around 15 LT) and amplitude similar to those observed in TRMM PR observations. Meanwhile, the resolution dependences in phase and amplitude are negligibly small over ocean domains. The different sensitivity against the horizontal resolution attributes to the different structures and life cycles of convective systems between land and ocean. The NICAM simulation revealed that the diurnal cycle of rainfall over the maritime continent is strongly coupled with the land-sea breeze systems controlling a convergence/divergence pattern in the lower troposphere around the islands. Additionally, the analysis on the cold pool events suggests that the cold pool is often formed over the open ocean where the precipitation intensity is high, and cold pool propagation is related to the diurnal cycle of precipitation as well as the land-sea breeze.

  6. Evaluating the Diurnal Cycle of Upper Tropospheric Humidity in Two Different Climate Models Using Satellite Observations

    DOE PAGESBeta

    Kottayil, Ajil; John, Viju; Buehler, Stefan; Mohanakumar, Kesavapillai

    2016-04-13

    The diurnal cycle of upper tropospheric humidity (UTH) is known to be influenced by such processes as convection and the formation of clouds which are parameterized in current global climate models. In this study, we evaluate the performance of two climate models, the Community Atmospheric Model version 5 (CAM-5) and the Global Atmosphere 3.0 (GA-3) model in simulating the diurnal cycle of UTH (represented by a combination of sinusoids of 12 and 24 h periods) by comparing with microwave and infrared (IR) measurements (where available). These comparisons were made over two convective land regions in South America and Africa, andmore » over oceanic regions in the Atlantic, Indian and West Pacific for the month of January 2007. We analyzed how the diurnal cycles from IR and microwave instruments differ, and the reason for the differences. Our study suggests that the differences in the diurnal cycles of IR and microwave UTH result from sampling differences due to the presence of clouds. Lastly, as noted by earlier studies, the models exhibit considerable discrepancies in diurnal amplitude and phase relative to observations, and these discrepancies have different magnitudes over land and ocean.« less

  7. Solar cycle, seasonal, and diurnal variations of subauroral ion drifts: Statistical results

    NASA Astrophysics Data System (ADS)

    He, Fei; Zhang, Xiao-Xin; Chen, Bo

    2014-06-01

    The solar cycle, seasonal, and diurnal variations of the subauroral ion drifts (SAIDs) are investigated for the first time to use such a large database of 18,226 SAID events observed by the DMSP satellites during 1987-2012. Statistical results show that SAIDs occur mostly at 60.1° invariant latitude and 2230 magnetic local time with a typical half width of 0.57°, move equatorward during high solar activities with large widths, and have two occurrence peaks in spring and fall equinoxes and two valleys in summer and winter solstices. The seasonal variation of SAID latitude has two valleys in spring and fall, and SAID width has a valley distribution with a minimum in summer. SAIDs exhibit a clear day-to-night difference in latitude. The diurnal variation of SAID width has a morning valley and an afternoon peak. The generation mechanism of SAID associated with the electron precipitation and the downward field-aligned current is also supported in this study.

  8. Diurnal variability of the hydrologic cycle in a general circulation model

    NASA Technical Reports Server (NTRS)

    Randall, David A.; Dazlich, Donald A.; HARSHVARDHAN

    1991-01-01

    In the present Colorado State University GCM simulation-based analysis of the diurnal and semidiurnal variability of precipitation, precipitable water, evaporation, cloudiness, horizontal moisture flux convergence, and cloud radiative forcing, a realistic afternoon precipitation maximum is obtained over land in warm rainy regions, as well as an early morning maximum over the oceans. The model has been further used to investigate the bases for the oceanic diurnal-precipitation cycle; the results thus obtained indicate that such an oceanic cycle occurs even in the absence of neighboring continents, and tends to have a morning maximum, although the observed phenomenon is generally stronger than the results indicate.

  9. Simulation of the annual and diurnal cycles of rainfall over South Africa by a regional climate model

    NASA Astrophysics Data System (ADS)

    Pohl, Benjamin; Rouault, Mathieu; Roy, Shouraseni Sen

    2014-10-01

    The capability of a current state-of-the-art regional climate model for simulating the diurnal and annual cycles of rainfall over a complex subtropical region is documented here. Hourly rainfall is simulated over Southern Africa for 1998-2006 by the non-hydrostatic model weather research and forecasting (WRF), and compared to a network of 103 stations covering South Africa. We used five simulations, four of which consist of different parameterizations for atmospheric convection at a 0.5 × 0.5° resolution, performed to test the physic-dependency of the results. The fifth experiment uses explicit convection over tropical South Africa at a 1/30° resolution. WRF simulates realistic mean rainfall fields, albeit wet biases over tropical Africa. The model mean biases are strongly modulated by the convective scheme used for the simulations. The annual cycle of rainfall is well simulated over South Africa, mostly influenced by tropical summer rainfall except in the Western Cape region experiencing winter rainfall. The diurnal cycle shows a timing bias, with atmospheric convection occurring too early in the afternoon, and causing too abundant rainfall. This result, particularly true in summer over the northeastern part of the country, is weakly physic-dependent. Cloud-resolving simulations do not clearly reduce the diurnal cycle biases. In the end, the rainfall overestimations appear to be mostly imputable to the afternoon hours of the austral summer rainy season, i.e., the periods during which convective activity is intense over the region.

  10. Diurnal cycling of urban aerosols under different weather regimes

    NASA Astrophysics Data System (ADS)

    Gregorič, Asta; Drinovec, Luka; Močnik, Griša; Remškar, Maja; Vaupotič, Janja; Stanič, Samo

    2016-04-01

    A one month measurement campaign was performed in summer 2014 in Ljubljana, the capital of Slovenia (population 280,000), aiming to study temporal and spatial distribution of urban aerosols and the mixing state of primary and secondary aerosols. Two background locations were chosen for this purpose, the first one in the city center (urban background - KIS) and the second one in the suburban background (Brezovica). Simultaneous measurements of black carbon (BC) and particle number size distribution of submicron aerosols (PM1) were conducted at both locations. In the summer season emission from traffic related sources is expected to be the main local contribution to BC concentration. Concentrations of aerosol species and gaseous pollutants within the planetary boundary layer are controlled by the balance between emission sources of primary aerosols and gases, production of secondary aerosols, chemical reactions of precursor gases under solar radiation and the rate of dilution by mixing within the planetary boundary layer (PBL) as well as with tropospheric air. Only local emission sources contribute to BC concentration during the stable PBL with low mixing layer height, whereas during the time of fully mixed PBL, regionally transported BC and other aerosols can contribute to the surface measurements. The study describes the diurnal behaviour of the submicron aerosol at the urban and suburban background location under different weather regimes. Particles in three size modes - nucleation (< 25 nm, NUM), Aitken (25 - 90 nm, AIM) and accumulation mode (90 - 800 nm, ACM), as well as BC mass concentration were evaluated separately for sunny, cloudy and rainy days, taking into account modelled values of PBL height. Higher particle number and black carbon concentrations were observed at the urban background (KIS) than at the suburban background location (Brezovica). Significant diurnal pattern of total particle concentration and black carbon concentration was observed at both

  11. The Diurnal Cycle in TOGA-COARE: Regional Scale Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Jia, Y.

    1999-01-01

    The diurnal variation of precipitation processes over the tropics is a well-known phenomenon and has been studied using surface rainfall data, radar reflectivity data, and satellite-derived cloudiness and precipitation. Recently, analyzed observations from Tropical Oceans and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) in the tropical western Pacific ocean to study the relevant mechanisms producing diurnal variation of precipitation. They found that the diurnal Sea surface temperature (SST) cycle is important for afternoon showers in the undisturbed periods and diurnal radiative processes for nocturnal rainfall. Cloud resolving models (CRMS) have been used to determine the mechanisms associated with diurnal variation of precipitating processes. CRMs allow explicit cloud-radiation and air-sea interactive processes. However, CRMs can be only used for idealized simulations (i.e., no feedback between clouds and their embedded large-scale environments; cyclic lateral boundary conditions and idealized initial conditions). In this study, the Penn State/NCAR Mesoscale Model (MM5) with improved physics (i.e., cloud microphysics, radiation, land-soil-vegetation-surface processes, and TOGA COARE flux scheme) and a multiple level nesting technique (covers the TOGA COARE LSA/IFA with a 54 km grid and can nest down to 18, 6 and possibly even 2 km) will be adopted for studying the diurnal variations of rainfall. We will examine precipitation processes over open ocean and over land. We will also perform sensitivity tests to determine how the radiative forcing and diurnal SST cycle affects the development of convection.

  12. LES of large wind farm during a diurnal cycle: Analysis of Energy and Scalar flux budgets

    NASA Astrophysics Data System (ADS)

    Sharma, V.; Calaf, M.; Parlange, M. B.

    2014-12-01

    With an expanding role of wind energy in satisfying energy demands around the world, wind farms are covering increasingly larger surfaces to the point where interaction between wind farms and the atmospheric boundary layer (ABL) might have significant implications. Furthermore, many wind farm sites lie over existing farmland for which water is a precious resource. In this context, a relevant question yet to be fully understood, is whether large wind farms alter near surface temperatures and evaporation rates and if so, by how much. In the present study, Large Eddy Simulation (LES) of a geostrophic wind driven ABL with two active scalars, temperature and specific humidity, in the presence of Coriolis forces with an embedded wind farm are performed. Multiple 'synthetic' diurnal cycles are simulated by imposing a time-varying surface temperature and specific humidity. Wind turbines are modeled using the "actuator disk" approach along with the flexibility to reorient according to varying flow directions. LES is performed using the "pseudo-spectral" approach implying that an infinitely large wind farm is simulated. Comparison of simulations with and without wind farms show clear differences in vertical profiles of horizontal velocity magnitude and direction, turbulent kinetic energy and scalar fluxes. To better understand these differences, a detailed analysis of the constituent terms of budget equations of mean and turbulent kinetic energy and sensible and latent heat fluxes has been performed for different stratification regimes as the ABL evolves during the diurnal cycle. The analyses help explain the effect of wind farms on the characteristics of the low-level jet, depth of the stable boundary layer, formation and growth of the convective boundary layer (CBL) and scalar fluxes at the surface.

  13. On the solar cycle dependence of the amplitude modulation characterizing the mid-latitude sporadic E layer diurnal periodicity

    NASA Astrophysics Data System (ADS)

    Pezzopane, M.; Pignalberi, A.; Pietrella, M.

    2016-01-01

    Spectral analyses are employed to investigate how the diurnal periodicity of the critical frequency of the sporadic E (Es) layer varies with solar activity. The study is based on ionograms recorded at the ionospheric station of Rome (41.8°N, 12.5°E), Italy, from 1976 to 2009, a period of time covering three solar cycles. It was confirmed that the diurnal periodicity is always affected by an amplitude modulation with periods of several days, which is the proof that Es layers are affected indirectly by planetary waves through their nonlinear interaction with atmospheric tides at lower altitudes. The most striking features coming out from this study is however that this amplitude modulation is greater for high-solar activity than for low-solar activity.

  14. What are the determinants of the diurnal cycle of cloud properties?

    NASA Astrophysics Data System (ADS)

    Fuchs, Julia; Cermak, Jan

    2015-04-01

    This study aims at untangling the influence of aerosols and meteorological factors on the diurnal cycle of cloud parameters based on a regional analysis of polar orbiting, geostationary satellite and reanalysis data. Aerosols affect the life time of clouds by changing their microphysical properties and dynamics dependent on the meteorological regime. In these systems, cloud properties change over time periods of hours and are highly variable spatially. Contributing to uncertainties of the Earth's radiation budget, the investigation of the aerosol-cloud-meteorology system from a regional perspective and on a daily basis is an important aspect of climate system research. In order to clarify to what extent cloud properties and their diurnal cycles are a result of cloud feedbacks to aerosols or meteorological conditions, multivariate statistics, in particular artificial neural networks, are used. Daily aerosol property data (MODIS) and meteorological parameters (ERA-Interim reanalysis) are used as input parameters and are related through a model to the observed output, i.e. diurnal cycles of cloud parameters (SEVIRI). Once the network is trained, the relevance of influencing factors for the diurnal cycle of cloud parameters is determined by sensitivity analysis.

  15. Changes in the diurnal cycles of precipitation over eastern China in the past 40 years

    NASA Astrophysics Data System (ADS)

    Yuan, Weihua; Yu, Rucong; Li, Jian

    2013-03-01

    This study analyzed the interdecadal changes in the diurnal variability of summer (June-August) precipitation over eastern China during the period 1966-2005 using hourly station rain gauge data. The results revealed that rainfall diurnal variations experienced significant interdecadal changes. Over the area to the south of the Yangtze River, as well as the area between the Yangtze and Yellow Rivers, the percentages of morning rainfall (0000-1200 LST) to total rainfall in terms of amount, frequency and intensity, all exhibited increasing interdecadal trends. On the contrary, over North China, decreasing trends were found. As a result, diurnal rainfall peaks also presented pronounced interdecadal variations. Over the area between the Yangtze and Yellow Rivers, there were 16 out of 46 stations with afternoon (1200-0000 LST) frequency peaks in the first 20 years of the 40-year period of study, while only eight remained in the latter 20 years. In North China, seven stations experienced the opposite changes, which accounted for about 21% of the total number of stations. The possible causes for the interdecadal changes in diurnal features were discussed. As the rainfall in the active monsoon period presents morning diurnal peaks, with afternoon peaks in the break period, the decrease (increase) of rainfall in the active monsoon period over North China (the area south of the Yangtze River and the area between the Yangtze and Yellow Rivers) may contribute to interdecadal changes in diurnal rainfall variability.

  16. On the Sensitivity of the Diurnal Cycle in the Amazon to Convective Intensity

    NASA Astrophysics Data System (ADS)

    Itterly, K. F.; Taylor, P. C.

    2015-12-01

    The sensitivity of the diurnal cycle to convective intensity is investigated for the wet season (DJF) and dry season (JJA) in the Amazon region. Model output reveals large water and energy budget errors in tropical rainforests, arising from a misrepresentation of the diurnal cycle of the complex processes inherent to diurnally forced moist convection. Daily, 3-hourly satellite observations of CERES Ed3a SYN1DEG TOA fluxes and 3-hourly TRMM 3B42 precipitation rate from 2002-2012 are split into regimes of convective intensity using percentile definitions for both daily minimum OLR and daily maximum precipitation rate to define regimes. These satellite-defined regimes are then co-located with convective parameters calculated from radiosonde observations. Diurnal statistics from satellite include: phase, amplitude, precipitation onset, precipitation duration and diurnal mean. The diurnal phase of outgoing longwave radiation (OLR) and longwave cloud forcing (LWCF) occurs several hours earlier on convective days compared to stable days, however, climatological precipitation phase is less sensitive to convective intensity, occurring between 1-4PM local time for all regimes and 1-2 hours later on very convective days, which is related to longer duration precipitation events from increased humidity. Diurnal convection in the Amazon is strongly related to 8AM values of both dynamic and thermodynamic variables, most of which are related to: the background moisture content of the troposphere, the stability of the lower troposphere, convective inhibition (CIN) and wind speed and direction in the column. Morning values of CIN, lifted condensation level (LCL), level of free convection (LFC) and equilibrium level (EL) are lower in DJF than JJA, and lower on very convective days than stable days for all stations. Higher background humidity is related to longer duration precipitation events (r-values between 0.4-0.6, depending on station and season), earlier phases and onset times

  17. Analysis of the Diurnal Cycle of Precipitation and its Relation to Cloud Radiative Forcing Using TRMM Products

    NASA Technical Reports Server (NTRS)

    Randall, David A.; Fowler, Laura D.; Lin, Xin

    1998-01-01

    In order to improve our understanding of the interactions between clouds, radiation, and the hydrological cycle simulated in the Colorado State University General Circulation Model (CSU GCM), we focused our research on the analysis of the diurnal cycle of precipitation, top-of-the-atmosphere and surface radiation budgets, and cloudiness using 10-year long Atmospheric Model Intercomparison Project (AMIP) simulations. Comparisons the simulated diurnal cycle were made against the diurnal cycle of Earth Radiation Budget Experiment (ERBE) radiation budget and International Satellite Cloud Climatology Project (ISCCP) cloud products. This report summarizes our major findings over the Amazon Basin.

  18. Diurnal anisotropy of cosmic rays during intensive solar activity for the period 2001-2014

    NASA Astrophysics Data System (ADS)

    Tezari, A.; Mavromichalaki, H.

    2016-07-01

    The diurnal variation of cosmic ray intensity, based on the records of two neutron monitor stations at Athens (Greece) and Oulu (Finland) for the time period 2001 to 2014, is studied. This period covers the maximum and the descending phase of the solar cycle 23, the minimum of the solar cycles 23/24 and the ascending phase of the solar cycle 24.These two stations differ in their geographic latitude and magnetic threshold rigidity. The amplitude and phase of the diurnal anisotropy vectors have been calculated on annual and monthly basis. From our analysis it is resulted that there is a different behaviour in the characteristics of the diurnal anisotropy during the different phases of the solar cycle, depended on the solar magnetic field polarity, but also during extreme events of solar activity, such as Ground Level Enhancements and cosmic ray events, such as Forbush decreases and magnetospheric events. These results may be useful to Space Weather forecasting and especially to Biomagnetic studies.

  19. The impact of the diurnal insolation cycle on the tropical cyclone heat engine

    NASA Astrophysics Data System (ADS)

    O'Neill, Morgan E.; Perez-Betancourt, Diamilet; Wing, Allison A.

    A hurricane, or tropical cyclone, is understood as a heat engine that moves heat from the warm sea surface to the cold tropopause. The efficiency of this engine depends in part on the strength and duration of solar heating. Over land, peak rainfall associated with individual thunderstorms occurs in the late afternoon. Over ocean, with its markedly higher surface heat capacity, deep convection responds more to radiational cooling than daytime surface heating. However, the role of daily varying solar forcing on the dynamics of tropical cyclones is poorly understood. Recently, Dunion et al. (2014) reported significant, repeating diurnal behavior propagating outward from tropical cyclone centers, using infrared imagery from nine years of North Atlantic tropical cyclones. We study the impact of the diurnal cycle on tropical cyclones using a high resolution 3D numerical model, the System for Atmospheric Modeling (Khairoutdinov and Randall 2003). Simulations are run with and without variable sunlight. We are able to reproduce the observational finding of Dunion et al. (2014), and further identify a diurnally-varying residual circulation in the tropical cyclone at midlevels. The impact of the diurnal cycle on the equilibrium dynamics of tropical cyclones is also discussed.

  20. Simulation of the Diurnal Cycle of Integrated Precipitable Water in the North American Monsoon Region

    NASA Astrophysics Data System (ADS)

    Ochoa, C. A.; Quintanar, A.; Adams, D. K.; Martinez-lopez, B.

    2015-12-01

    Organized deep convection over the North American monsoon region (NAM) is a salient climatic feature that has been the subject of several experimental campaigns and modeling efforts. Recently, however, in Mexico and the Caribbean, there has been mounting interest towards implementing low-cost, low-maintenance GPS-meteorological networks (TLALOCNet and COCOnet) that provide near real-time Integrated Precipitable Water data (IPW) into the assimilation cycle of regional models. A wealth of interesting new observational results concerning the link between the diurnal cycle of deep convection and the processes that could alter it at the surface and aloft has open up opportunities of model verification and improvements to the physics that are specific to subtropical deep convection. In this work, the diurnal cycle of IPW is studied using observational data collected during the North American Monsoon GPS Transect Experiment 2013 experiment and numerical simulations with the Weather Research and Forecasting model (WRF). WRF was run in climate mode to generate a simulation for the entire experiment using ECMWF ERA-Interim analysis data for initial and boundary conditions and spectral nudging. We classified the days during the experiment, according to type of mesoscale phenomena present each day and averaged days with same weather types in both data sets (observed and simulated). Preliminary results show that the simulated diurnal cycle of IPW is very sensitive to Land Use/Land Cover data and to initial and the boundary conditions. Preliminary results show that the simulated amplitude and phase of the diurnal cycle of IPW is well represented only when a more up-to-date LULC is used (MODIS v.s. 99 USGS LULC) and the Thompson mycrophysics scheme is used. In agreement with the previous results, modeled precipitation time series agree better with observed GPS-meterological station reports during the NAM 2013 experiment.

  1. Variability of radiatively forced diurnal cycle of intense convection in the tropical west pacific

    SciTech Connect

    Gray, W.M.; Sheaffer, J.D.; Thorson, W.B.

    1996-04-01

    Strong differences occur in daytime versus nighttime (DVN) net radiative cooling in clear versus cloudy areas of the tropical atmosphere. Daytime average cooling is approximately -0.7{degrees}C/day, whereas nighttime net tropospheric cooling rates are about -1.5{degrees}C/day, an approximately two-to-one difference. The comparatively strong nocturnal cooling in clear areas gives rise to a diurnally varying vertical circulation and horizontal convergence cycle. Various manifestations of this cyclic process include the observed early morning heavy rainfall maxima over the tropical oceans. The radiatively driven DVN circulation appears to strongly modulate the resulting diurnal cycle of intense convection which creates the highest, coldest cloudiness over maritime tropical areas and is likely a fundamental mechanism governing both small and large scale dynamics over much of the tropical environment.

  2. The diurnal cycle of water ice on comet 67P/Churyumov-Gerasimenko.

    PubMed

    De Sanctis, M C; Capaccioni, F; Ciarniello, M; Filacchione, G; Formisano, M; Mottola, S; Raponi, A; Tosi, F; Bockelée-Morvan, D; Erard, S; Leyrat, C; Schmitt, B; Ammannito, E; Arnold, G; Barucci, M A; Combi, M; Capria, M T; Cerroni, P; Ip, W-H; Kuehrt, E; McCord, T B; Palomba, E; Beck, P; Quirico, E

    2015-09-24

    Observations of cometary nuclei have revealed a very limited amount of surface water ice, which is insufficient to explain the observed water outgassing. This was clearly demonstrated on comet 9P/Tempel 1, where the dust jets (driven by volatiles) were only partially correlated with the exposed ice regions. The observations of 67P/Churyumov-Gerasimenko have revealed that activity has a diurnal variation in intensity arising from changing insolation conditions. It was previously concluded that water vapour was generated in ice-rich subsurface layers with a transport mechanism linked to solar illumination, but that has not hitherto been observed. Periodic condensations of water vapour very close to, or on, the surface were suggested to explain short-lived outbursts seen near sunrise on comet 9P/Tempel 1. Here we report observations of water ice on the surface of comet 67P/Churyumov-Gerasimenko, appearing and disappearing in a cyclic pattern that follows local illumination conditions, providing a source of localized activity. This water cycle appears to be an important process in the evolution of the comet, leading to cyclical modification of the relative abundance of water ice on its surface. PMID:26399830

  3. Removing Diurnal Cycle Contamination in Satellite-Derived Tropospheric Temperatures: Understanding Tropical Tropospheric Trend Discrepancies

    NASA Astrophysics Data System (ADS)

    Po-Chedley, S.; Thorsen, T. J.; Fu, Q.

    2014-12-01

    Tropical mid-tropospheric temperature (TMT) time series have been constructed by several independent research teams using satellite microwave sounding unit (MSU) measurements beginning in 1978 and advanced MSU (AMSU) measurements since 1998. Despite careful efforts to homogenize the MSU/AMSU measurements, tropical TMT trends disagree by a factor of three even though each analysis uses the same basic data. Previous studies suggest that the discrepancy in tropical TMT temperature trends is largely caused by differences in both the NOAA-9 warm target factor and diurnal drift corrections used by various teams to homogenize the MSU/AMSU measurements. This work introduces a new observationally-based method for removing biases related to satellite diurnal drift. The method relies on minimizing inter-satellite and inter-node drifts by subtracting out a common diurnal cycle determined via linear regression. It is demonstrated that this method is effective at removing intersatellite biases and biases between the ascending (PM) and descending (AM) node of individual satellites in the TMT time series. After TMT bias correction, the ratio of tropical tropospheric temperature trends relative to surface temperature trends is in accord with the ratio from global climate models. It is shown that bias corrections for diurnal drift based on a climate model produce tropical trends very similar to those from the observationally-based correction, with a trend differences smaller than 0.02 K decade-1. Differences among various TMT datasets are explored further. Tropical trends from this work are comparable to those from the Remote Sensing System (RSS) and NOAA datasets despite small differences. Larger differences between this work and UAH are attributed to differences in the treatment of the NOAA-9 target factor and the UAH diurnal cycle correction.

  4. Diurnal Cycle of Convection in the East Pacific ITCZ during EPIC-2001

    NASA Technical Reports Server (NTRS)

    Boccippio, Dennis J.; Petersen, Walter A.; Cifelli, Robert; Rutledge, Steven A.; Arnold, James O. (Technical Monitor)

    2002-01-01

    During the last three weeks of September 2001, the EPIC-2001 intensive field campaign focused on studies of deep convection in the ITCZ over the Mexican warm pool region (10N, 95W) of the East Pacific. This study focuses on the pronounced observed diurnal cycle of environmental and convective parameters within the experiment domain. Data from three primary sources are examined: the R/V Ronald H. Brown C-band weather radar, 4-hourly soundings from the Brown and the Global Atmospherics, Inc. National Lightning Detection Network (long range product). Satellite data from TRMM, GOES and OV-1 are also used. The domain boundary layer shows a robust daily evolution of moist enthalpy (as reflect by equivalent potential temperature, theta-e, or wet bulb potential temperature, theta-w), with contributions from changes in both dry and moist entropy. Peak theta-w is found after local nightfall; the average diurnal range of theta-w is approximately 1 deg C. A composite diurnal cycle of convective properties was derived from the C-band volume scans, sampled continuously through the experiment at 10 minute updates. Products derived from the volumetric data include a surface PPI, 15 and 30 dBZ echo top height, vertically integrated liquid, and 6 km (mixed phase region) reflectivity CAPPIs. For almost all products, the parameter means showed virtually no diurnal cycle. However, for the upper-level products, the parameter spectra showed a clear peak in the occurrence of deep/vigorous convection (the "tail end of the distribution") between 7-9 UTC (1-3 AM local), while overall frequency of occurrence peaked later, from 12-15 UTC (6-9 AM local). This represents a daily "outbreak" of isolated deep cells a couple of hours after sunset and subsequent growth, organization and decay through the nighttime hours. The coherence of the diurnal cycle of the convective spectrum is impressive given the wide variety of convective organization observed during the experiment, and given the modulation

  5. Large Eddy Simulation of the Diurnal Cycle in Southeast Pacific Stratocumulus

    SciTech Connect

    Caldwell, P; Bretherton, C

    2008-03-03

    This paper describes a series of 6 day large eddy simulations of a deep, sometimes drizzling stratocumulus-topped boundary layer based on forcings from the East Pacific Investigation of Climate (EPIC) 2001 field campaign. The base simulation was found to reproduce the observed mean boundary layer properties quite well. The diurnal cycle of liquid water path was also well captured, although good agreement appears to result partially from compensating errors in the diurnal cycles of cloud base and cloud top due to overentrainment around midday. At other times of the day, entrainment is found to be proportional to the vertically-integrated buoyancy flux. Model stratification matches observations well; turbulence profiles suggest that the boundary layer is always at least somewhat decoupled. Model drizzle appears to be too sensitive to liquid water path and subcloud evaporation appears to be too weak. Removing the diurnal cycle of subsidence had little effect on simulated cloud albedo. Simulations with changed droplet concentration and drizzle susceptibility showed large liquid water path differences at night, but differences were quite small at midday. Droplet concentration also had a significant impact on entrainment, primarily through droplet sedimentation feedback rather than through drizzle processes.

  6. Using Daily Ocean Wind Vector and Speed Measurements to Estimate the Diurnal Cycle Modes

    NASA Astrophysics Data System (ADS)

    Turk, F. J.; Hristova-Veleva, S. M.; Haddad, Z. S.

    2014-12-01

    Over many oceanic regions, the surface wind varies widely throughout the day, owing to various meteorological forcings, such as land/sea temperature differences near coasts, or variations associated with tropical precipitation processes. Over the tropical oceans, several coarsely spaced buoy networks (TAO/TRITON in the Pacific, PIRATA in the Atlantic, RAMA in the Indian Ocean) are maintained as part of the Global Tropical Moored Buoy Array. For finer global scale analysis, further improvements to the modeling and understanding of physical processes within the coupled atmosphere ocean is based upon analysis of a disparate collection of low Earth orbiting (LEO) satellite based ocean surface wind data records. Since LEO satellite observations represent intermittently spaced, instantaneous snapshots, sampling against the backdrop of continuously changing physical processes, its is important to carefully merge and analyze the multiple satellite datasets in order to extract meaningful information on diurnal and semi-diurnal wind cycles. Early analysis of an investigation are described whereby multi-year collections of global sun-synchronous and asynchronous orbiting satellite ocean wind data are used to investigate the diurnal and semi-diurnal ocean wind vector variability over certain regions. A unique feature of the effort is the utilization of all capable sensors, including both wind speed and wind vector capable sensors, using overlapping asynchronous satellite observations to establish self-consistency, including inter-sensor bias correction to a common reference platform.

  7. The simulation of the diurnal cycle of convective precipitation over land in a global model

    NASA Astrophysics Data System (ADS)

    Bechtold, P.; Chaboureau, J. P.; Beljaars, A.; Betts, A. K.; Köhler, M.; Miller, M.; Redelsperger, J. L.

    2004-10-01

    In the context of the European Cloud Systems project, the problem of the simulation of the diurnal cycle of convective precipitation over land is addressed with the aid of cloud-resolving (CRM) and single-column (SCM) model simulations of an idealized midlatitude case for which observations of large-scale and surface forcing are available. The CRM results are compared to different versions of the European Centre for Medium-Range Weather Forecasts (ECMWF) convection schemes using different convective trigger procedures and convective closures. In the CRM, maximum rainfall intensity occurs at 15 h (local time). In this idealized midlatitude case, most schemes do not reproduce the afternoon precipitation peak, as (i) they cannot reproduce the gradual growth (typically over 3 hours) of the deep convective cloud layer and (ii) they produce a diurnal cycle of precipitation that is in phase with the diurnal cycle of the convective available potential energy (CAPE) and the convective inhibition (CIN), consistent with the parcel theory and CAPE closure used in the bulk mass-flux scheme. The scheme that links the triggering to the large-scale vertical velocity gets the maximum precipitation at the right time, but this may be artificial as the vertical velocity is enforced in the single-column context. The study is then extended to the global scale using ensembles of 72-hour global forecasts at resolution T511 (40 km), and long-range single 40-day forecasts at resolution T159 (125 km) with the ECMWF general-circulation model. The focus is on tropical South America and Africa where the diurnal cycle is most pronounced. The forecasts are evaluated against analyses and observed radiosonde data, as well as observed surface and satellite-derived rainfall rates. The ECMWF model version with improved convective trigger produces the smallest biases overall. It also shifts the rainfall maximum to 12 h compared to 9.5 h in the original version. In contrast to the SCM, the vertical

  8. Diurnal Cycle Variability of Rainfall Over the Indian Region: Perspectives From the TRMM Satellite

    NASA Astrophysics Data System (ADS)

    Sahany, S.; Venugopal, V.; Nanjundiah, R. S.

    2008-12-01

    Using the TRMM 3-hourly, 0.25x0.25 degree 3B42 rainfall product for nine years (1999-2007), we characterise the summer season (JJAS) diurnal cycle of rainfall over the Indian land and its neighbouring oceans (10S to 35N, 60E to 100E). Most previous studies have provided an analysis of a single or few years of satellite- or station-based rainfall data (e.g., Basu, 2007; Yang and Smith, 2006; Nesbitt and Zipser, 2003) and, to our knowledge, this is one of the first studies that aims to exhaustively characterise the diurnal scale statistical characteristics of rainfall over the Indian and surrounding regions. Using harmonic analysis, we extract, at each grid point, every year, the signal corresponding to time periods smaller than 1 day, i.e., the signal that relates to diurnal and sub-diurnal variability. Subsequently, the time of rainfall peak for this filtered signal, referred to as the "peak hour," is estimated, with care taken to eliminate spurious peaks arising out of Gibbs oscillations. Our analysis suggests that the mode of the peak hour (of the diurnal-scale rainfall) over a significant part of Indian land is at 12 UTC (i.e. 5:30PM local time), a finding similar to that reported in previous studies (e.g., Liu and Zipser, 2008; Krishnamurti and Kishtawal, 2000). The Himalayan foothills were found to have a mode of peak hour at 21 UTC (i.e. 2:30AM local time), whereas over the Burmese mountains the rainfall peaks at 9 to 12 UTC (i.e. 3:30 PM to 6:30 PM local time). In addition, over the Bay of Bengal, there is a stratified spatial structure of mode of the peak hour of diurnal rainfall at 6, 9 and 12 UTC from North central to South Bay. This finding, not reported before, could be seen to be consistent with southward propagation of the diurnal rainfall pattern (e.g., Hoyos and Webster, 2007; Zuidema, 2003). We also find that the Arabian sea (to the east of 65E and north of the Equator, along a region where it rains for more than 50% of the time) shows a peak hour

  9. Seasonal Change of the Diurnal Cycle of Precipitation over Japan and Malaysia.

    NASA Astrophysics Data System (ADS)

    Oki, Taikan; Musiake, Katumi

    1994-12-01

    The diurnal cycle of precipitation is investigated using ground-based hourly observations for more than 10 years both in Japan and Malaysia. The diurnal cycle of precipitation in Japan is classified into three clusters. The first one has a peak in the morning, and the stations categorized into this cluster are located in coastal regions. The second cluster has two peaks in the morning and in the evening. These stations are located in an inland region. The morning peak in the above two clusters is dominant in June, when it is `baiu' in Japan. Baiu is the rainy season related to the southwest Asian monsoon. The third cluster is an exceptional case. No morning peak is observed in the stations of the third cluster and they have a comparatively strong evening peak.In the case of the Malay Peninsula, the inland region has a pronounced peak of rainfall at 1600 LST; the magnitude exceeds the mean of each month by 200%. This evening peak is too sharp to be represented by a 24-h-cycle sine wave decomposed by Fourier transform. The intensity also becomes higher at the peak time (1500 LST). The magnitude of the diurnal cycle of mean intensity is larger than the annual cycle of monthly mean intensity. The morning peak of precipitation is observed during the southwest monsoon season on the west coast, and during the northeast monsoon season on the east coast. The intensity of precipitation is not significantly high during this period; namely, the increase of the probability or the duration of precipitation forms this morning peak. These evidences indicate the mechanism of the convective rainfall by the thermodynamic forcing in the evening, and the low-level convergence between the local land sea breeze and the predominant monsoon wind in the morning.

  10. Ecotypic variability in the metabolic response of seeds to diurnal hydration-dehydration cycles and its relationship to seed vigor.

    PubMed

    Bai, Bing; Sikron, Noga; Gendler, Tanya; Kazachkova, Yana; Barak, Simon; Grafi, Gideon; Khozin-Goldberg, Inna; Fait, Aaron

    2012-01-01

    Seeds in the seed bank experience diurnal cycles of imbibition followed by complete dehydration. These conditions pose a challenge to the regulation of germination. The effect of recurring hydration-dehydration (Hy-Dh) cycles were tested on seeds from four Arabidopsis thaliana accessions [Col-0, Cvi, C24 and Ler]. Diurnal Hy-Dh cycles had a detrimental effect on the germination rate and on the final percentage of germination in Col-0, Cvi and C24 ecotypes, but not in the Ler ecotype, which showed improved vigor following the treatments. Membrane permeability measured by ion conductivity was generally increased following each Hy-Dh cycle and was correlated with changes in the redox status represented by the GSSG/GSH (oxidized/reduced glutathione) ratio. Among the ecotypes, Col-0 seeds displayed the highest membrane permeability, whilst Ler was characterized by the greatest increase in electrical conductivity following Hy-Dh cycles. Following Dh 2 and Dh 3, the respiratory activity of Ler seeds significantly increased, in contrast to the other ecotypes, indicative of a dramatic shift in metabolism. These differences were associated with accession-specific content and patterns of change of (i) cell wall-related laminaribiose and mannose; (ii) fatty acid composition, specifically of the unsaturated oleic acid and α-linoleic acid; and (iii) asparagine, ornithine and the related polyamine putrescine. Furthermore, in the Ler ecotype the content of the tricarboxylic acid (TCA) cycle intermediates fumarate, succinate and malate increased in response to dehydration, in contrast to a decrease in the other three ecotypes. These findings provide a link between seed respiration, energy metabolism, fatty acid β-oxidation, nitrogen mobilization and membrane permeability and the improved germination of Ler seeds following Hy-Dh cycles. PMID:22156384

  11. Rectification of the Diurnal Cycle and the Impact of Islands on the Tropical Climate

    NASA Astrophysics Data System (ADS)

    Cronin, T. W.; Emanuel, K.

    2012-12-01

    Tropical islands are observed to be rainier than nearby ocean areas, and rainfall over the islands of the Maritime Continent plays an important role in the atmospheric general circulation. Convective heating over tropical islands is also strongly modulated by the diurnal cycle of solar insolation and surface enthalpy fluxes, and convective parameterizations in general circulation models are known to reproduce the phase and amplitude of the observed diurnal cycle of convection rather poorly. Connecting these ideas suggests that poor representation of the diurnal cycle of convection and precipitation over tropical islands in climate models may be a significant source of model biases. Here, we explore how a highly idealized island, which differs only in heat capacity from the surrounding ocean, could rectify the diurnal cycle and impact the tropical climate, especially the spatial distribution of rainfall. We perform simulations of radiative-convective equilibrium with the System for Atmospheric Modeling cloud-system-resolving model, with interactive surface temperature and a varied surface heat capacity. For the case of relatively small-scale simulations, where a shallow (~5 cm) slab-ocean "swamp island" surface is embedded in a deeper (~1 m) slab-ocean domain, the precipitation rate over the island is more than double the domain average value, with island rainfall occurring primarily in a strong regular convective event each afternoon. In addition to this island precipitation enhancement, the upper troposphere also warms with the inclusion of a low- heat capacity island. We discuss two radiative mechanisms that contribute to both island precipitation enhancement and free tropospheric warming, by producing a top-of-atmosphere radiative surplus over the island. The first radiative mechanism is a clear-sky effect, related to nonlinearities in the surface energy budget, and differences in how surface energy balance is achieved over surfaces of different heat capacities

  12. Dependence of upper atmosphere photochemistry on the shape of the diurnal cycle of the photolysis rates

    NASA Astrophysics Data System (ADS)

    Montecinos, S.; Barrientos, P.

    2006-03-01

    A photochemical model of the atmosphere constitutes a non-linear, non-autonomous dynamical system, enforced by the Earth's rotation. Some studies have shown that the region of the mesopause tends towards non-linear responses such as period-doubling cascades and chaos. In these studies, simple go approximations for the diurnal variations of the photolysis rates are assumed. The goal of this article is to investigate what happens if the more realistic, calculated photolysis rates are introduced. It is found that, if the usual approximations-sinusoidal and step functions-are assumed, the responses of the system are similar: it converges to a 2-day periodic solution. If the more realistic, calculated diurnal cycle is introduced, a new 4-day subharmonic appear.

  13. Satellite-based Dust Source Identification over North Africa: Diurnal Cycle, Meteorological Controls, and Interannual Variability

    NASA Astrophysics Data System (ADS)

    Schepanski, Kerstin; Tegen, Ina; Macke, Andreas

    2010-05-01

    Mineral dust aerosol emitted from arid and semi-arid areas impacts on the weather and climate system by affecting e.g. radiation fluxes and nutrient cycles. To estimate the effect of dust aerosol, detailed knowledge on the spatio-temporal distribution of active dust sources is necessary. For a better representation of dust-related processes in numerical models and climate change projections the knowledge on the natural variability of dust source activity has to be improved. As dust sources are mostly located over remote areas satellite observations are suitable for identifying active dust sources. The accuracy of dust source identification using such an indirect method is limited by the temporal resolution and the ambiguities of the retrieval. Here, a data set on the spatial (1°x1°) and temporal (3-hourly) distribution of dust source activations (DSA) over North Africa is compiled by analyzing 15-minute Meteosat Second Generation (MSG) infra-red (IR) dust index images since March 2006. The index is designed using radiances measured by the Spinning Enhanced Visible and Infra-Red Imager (SEVIRI) on-board MSG at 8.7 µm, 10.8 µm and 12.0 µm which are converted to brightness temperatures (BTs). To strengthen the dust signal, differences of BTs are used to compute RGB-composite images. This newly data set providing information on the diurnal cycle of dust emission has been used (1) to identify most active dust source areas, and (2) to investigate on the temporal distribution of DSAs. Over the Sahara Desert 65% of dust sources become active during 06-09 UTC pointing towards an important role of the break-down of the nocturnal low-level jet (LLJ) for dust mobilization besides other meteorological features like density currents, haboobs, and cyclones. Furthermore the role of the nocturnal LLJs for dust mobilization over the Sahara is investigated by weather observations and a regional modeling study. Four years of DSA observations indicate an interannual variability in

  14. Diurnal Cycle of Rainfall in Taiwan during SoWMEX/TiMREX (2008)

    NASA Astrophysics Data System (ADS)

    Ruppert, J. H.; Johnson, R. H.

    2012-12-01

    The diurnal cycle in circulations and rainfall is investigated in Taiwan's heavy rain ("Mei-yu") season during the 2008 Southwest Monsoon Experiment/Terrain-influenced Monsoon Rainfall Experiment (SoWMEX/TiMREX), with focus on two periods; one undisturbed and one disturbed. The study employs the Weather Research and Forecasting Data Assimilation system to generate a reanalysis based on SoWMEX/TiMREX datasets. The undisturbed period (22-29 May; UNDIST) was characterized by pronounced diurnal variation in circulations and latent heating profiles over and around Taiwan. While resembling land-sea/mountain-valley circulations, this variation was manifest as a modification of the flow blocking pattern: at night, the flow is strongly deflected around Taiwan's Central Mountain Range (CMR), and rainfall is focused near areas of offshore/upwind confluence; during the day, boundary layer warming enables the monsoon flow to traverse the terrain, and convection develops along the windward coastal plains/foothills in response. Lower tropospheric latent cooling develops over Taiwan with the evening transition to stratiform rain, which precedes the nocturnal development of downslope/offshore surface flows. During a disturbed period (31 May-4 June; DIST), deep moisture, strengthened monsoon flow, and pronounced convergence along a Mei-yu front created a more favorable environment for widespread deep convection, which led to a shift in rainfall to the higher slopes of the CMR. Although diurnal surface flows were reduced during DIST, rainfall response to these flows was pronounced, suggesting heightened sensitivity of rainfall to the diurnal cycle when the environment is primed for convection.

  15. What the diurnal cycle of precipitation tells us about land-atmosphere coupling strength

    NASA Astrophysics Data System (ADS)

    Ferguson, Craig; Song, Hyojong; Roundy, Joshua

    2015-04-01

    The key attributes of a coupled forecast model are the coupling strengths between the land-atmosphere and ocean-atmosphere schemes. If a model cannot skillfully capture the diurnal cycle of clouds and precipitation, then it likely cannot be expected to yield accurate long-term climate projections. The seasonal drought forecast skill shortfalls of the U.S. NCEP Coupled Forecast System Version 2 (CFSv2) have been directly linked to its unrealistically strong land-atmosphere coupling strength. Most models can be similarly categorized, which is to say, sensitivity to the land physics (i.e., soil moisture constraints on evapotranspiration) is too strong. In nature, the land signal: noise ratio appears to be at a much lower value. Diagnosing land-atmosphere coupling strength requires at a minimum: surface soil moisture state, surface turbulent heat fluxes, and atmospheric moisture and instability. Full-on diagnosis would entail hacking into the code and inserting a number of tracers. This study addresses the question: What if, given the soil wetness anomaly, model biases in coupling sign and/or strength could be diagnosed from phase shifts in the diurnal precipitation frequency cycle? We use 34-years of output from the North American Regional Reanalysis (NARR) and North American Land Data Assimilation System Phase 2 (NLDAS-2) to investigate the variation in diurnal precipitation frequency cycle between so-called "wet-advantage" and "dry-advantage" coupling regimes over the U.S. southern Great Plains. Wet-advantage occurs when the atmospheric state is closer to the wet adiabatic rate and convection is triggered by a strong increase in the moist static energy from the surface. In contrast, dry-advantage occurs when the atmosphere is drier and the temperature profile is close to the dry adiabatic lapse rate, which favors convection over areas of large boundary layer growth due to high sensible heat fluxes at the surface. We find that there is a significant difference in the

  16. Influence of Observed Diurnal Cycles of Aerosol Optical Depth on Aerosol Direct Radiative Effect

    NASA Technical Reports Server (NTRS)

    Arola, A.; Eck, T. F.; Huttunen, J.; Lehtinen, K. E. J.; Lindfors, A. V.; Myhre, G.; Smirinov, A.; Tripathi, S. N.; Yu, H.

    2013-01-01

    The diurnal variability of aerosol optical depth (AOD) can be significant, depending on location and dominant aerosol type. However, these diurnal cycles have rarely been taken into account in measurement-based estimates of aerosol direct radiative forcing (ADRF) or aerosol direct radiative effect (ADRE). The objective of our study was to estimate the influence of diurnal aerosol variability at the top of the atmosphere ADRE estimates. By including all the possible AERONET sites, we wanted to assess the influence on global ADRE estimates. While focusing also in more detail on some selected sites of strongest impact, our goal was to also see the possible impact regionally.We calculated ADRE with different assumptions about the daily AOD variability: taking the observed daily AOD cycle into account and assuming diurnally constant AOD. Moreover, we estimated the corresponding differences in ADREs, if the single AOD value for the daily mean was taken from the the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra or Aqua overpass times, instead of accounting for the true observed daily variability. The mean impact of diurnal AOD variability on 24 h ADRE estimates, averaged over all AERONET sites, was rather small and it was relatively small even for the cases when AOD was chosen to correspond to the Terra or Aqua overpass time. This was true on average over all AERONET sites, while clearly there can be much stronger impact in individual sites. Examples of some selected sites demonstrated that the strongest observed AOD variability (the strongest morning afternoon contrast) does not typically result in a significant impact on 24 h ADRE. In those cases, the morning and afternoon AOD patterns are opposite and thus the impact on 24 h ADRE, when integrated over all solar zenith angles, is reduced. The most significant effect on daily ADRE was induced by AOD cycles with either maximum or minimum AOD close to local noon. In these cases, the impact on 24 h ADRE was

  17. Diurnal cycle in convergence patterns in the boundary layer east of the Andes and convection

    NASA Astrophysics Data System (ADS)

    Nicolini, Matilde; Skabar, Yanina García

    2011-06-01

    The South American Low-Level Jet Experiment (SALLJEX) provided a unique dataset to investigate the existence of a mesoscale low-level circulation and of a diurnal cycle in its related convergence pattern over the Southeastern South American region east of the Andes, as well as its relationship with deep convection during the warm season. The present paper builds upon high-resolution analyses produced, assimilating the data collected during the SALLJEX field campaign using BRAMS, and explores their capability to reproduce mesoscale circulations not resolved by the low density observational network available in this region. Results of the analyses show a diurnal oscillation signal in the mean boundary layer convergence pattern over the plains with a nocturnal (daytime) convergence (divergence) maximum. These results are coherent with previous findings of a nocturnal phase in the mature stage of organized deep convection and related precipitation in subtropical latitudes east of the Andes during the warm season. The diurnal cycle of convergence/divergence in the boundary layer is described over a 15-day period, during which different synoptic conditions occurred. During weakly forced environments a regime characterized by nocturnal eastward anomaly flow and convergence and daytime westward anomaly flow and divergence related to a mesoscale northwestern mountain-central plain flow regime dominates over the plains between the Andes Mountains, the Parana River Valley, and the southern Brazil mountain range. In contrast, during synoptic conditions dominated by the presence of a deep thermal low over northwestern Argentina and a related low-level jet, convergence at night is mainly accomplished by the predominantly meridional low-level jet, which exhibits an anomalous weak wind speed diurnal cycle with respect to its summer climatological mean. On the other hand daytime divergence is completely produced by the zonal wind component as in the previous synoptic situation

  18. Sulfur redox chemistry governs diurnal antimony and arsenic cycles at Champagne Pool, Waiotapu, New Zealand

    NASA Astrophysics Data System (ADS)

    Ullrich, Maria K.; Pope, James G.; Seward, Terry M.; Wilson, Nathaniel; Planer-Friedrich, Britta

    2013-07-01

    Champagne Pool, a sulfidic hot spring in New Zealand, exhibits distinct diurnal variations in antimony (Sb) and arsenic (As) concentrations, with daytime high and night-time low concentrations. To identify the underlying mobilization mechanisms, five sites along the drainage channel of Champagne Pool were sampled every 2 h during a 24 h period. Temporal variations in elemental concentrations and Sb, As, and sulfur (S) speciation were monitored in the discharging fluid. Total trace element concentrations in filtered and unfiltered samples were analyzed using ICP-MS, and Sb, As and S species were determined by IC-ICP-MS. Sulfur speciation in the drainage channel was dominated by thiosulfate and sulfide at night, while sulfate dominated during the day. The distinct diurnal changes suggest that the transformations are caused by phototrophic sulfur-oxidizing bacteria. These bacteria metabolize thiosulfate and sulfide in daylight to form sulfate and, as suggested by modeling with PhreeqC, elemental sulfur. Sulfide consumption during the day results in undersaturation of antimony sulfides, which triggers the additional release of dissolved Sb. For As, diurnal cycles were much more pronounced in speciation than in total concentrations, with di- and trithioarsenate forming at night due to excess sulfide, and monothioarsenate forming from arsenite and elemental sulfur during the day. Sulfur speciation was thus found to control Sb and As in terms of both solubility and speciation.

  19. Simulations of polarization dependent contrast during the diurnal heating cycle for passive millimeter-wave imagery

    NASA Astrophysics Data System (ADS)

    Wilson, John P.; Murakowski, Maciej; Schuetz, Christopher A.; Prather, Dennis W.

    2013-09-01

    Passive millimeter-wave (mmW) sensors are especially suited to persistent surveillance applications due to their ability to operate during day/night conditions and through transient atmospheric obscurants such as clouds, rain and fog. The contrast of targets will change throughout a diurnal heating cycle and this change will be polarization dependent. Simulations are presented from a ray tracing program developed for the mmW regime that has been modified to account for polarization information. Results are shown demonstrating periods during the day when the contrast of certain targets drop to zero for a linear polarization state while the orthogonal state still maintains a high contrast.

  20. Technical Note: Glacial influence in tropical mountain hydrosystems evidenced by the diurnal cycle in water levels

    NASA Astrophysics Data System (ADS)

    Cauvy-Fraunié, S.; Condom, T.; Rabatel, A.; Villacis, M.; Jacobsen, D.; Dangles, O.

    2013-12-01

    Worldwide, the rapid shrinking of glaciers in response to ongoing climate change is modifying the glacial meltwater contribution to hydrosystems in glacierized catchments. Determining the influence of glacial runoff to streams is therefore of critical importance to evaluate potential impact of glacier retreat on water quality and aquatic biota. This task has challenged both glacier hydrologists and ecologists over the last 20 yr due to both structural and functional complexity of the glacier-stream system interface. Here we propose quantifying the diurnal cycle amplitude of the streamflow to determine the glacial influence in glacierized catchments. We performed water-level measurements using water pressure loggers over 10 months at 30 min time steps in 15 stream sites in 2 glacier-fed catchments in the Ecuadorian Andes (> 4000 m a.s.l.) where no perennial snow cover is observed outside the glaciers. For each stream site, we performed wavelet analyses on water-level time series, determined the scale-averaged wavelet power spectrum at 24 h scale and defined three metrics, namely the power, frequency and temporal clustering of the diurnal flow variation. The three metrics were then compared to the percentage of the glacier cover in the catchments, a metric of glacial influence widely used in the literature. As expected, we found that the diurnal variation power of glacier-fed streams decreased downstream with the addition of non-glacial tributaries. We also found that the diurnal variation power and the percentage of the glacier cover in the catchment were significantly positively correlated. Furthermore, we found that our method permits the detection of glacial signal in supposedly non-glacial sites, thereby revealing glacial meltwater resurgence. While we specifically focused on the tropical Andes in this paper, our approach to determine glacial influence may have potential applications in temperate and arctic glacierized catchments. The measure of diurnal water

  1. Discovery of a widespread low-latitude diurnal CO2 frost cycle on Mars

    NASA Astrophysics Data System (ADS)

    Piqueux, Sylvain; Kleinböhl, Armin; Hayne, Paul O.; Heavens, Nicholas G.; Kass, David M.; McCleese, Daniel J.; Schofield, John T.; Shirley, James H.

    2016-07-01

    While the detection of CO2 ice has only been reported outside the Martian polar regions at very high elevation (i.e., Elysium, Olympus Mons, and the Tharsis Montes), nighttime surface observations by the Mars Climate Sounder on board the Mars Reconnaissance Orbiter document the widespread occurrence of atmospherically corrected ground temperatures consistent with the presence of extensive carbon dioxide frost deposits in the dusty low thermal inertia units at middle/low latitudes. Thermal infrared emissivities, interpreted in conjunction with mass balance modeling, suggest micrometer size CO2 ice crystals forming optically thin layers never exceeding a few hundreds of microns in thickness (i.e., 10-2 kg m-2) locally, which is insufficient to generate a measurable diurnal pressure cycle (<<0.1% of the Martian atmosphere). Atmospheric temperatures at middle/low latitudes are not consistent with precipitation of CO2 ice, suggesting that condensation occurs on the surface. The recurring growth and sublimation of CO2 ice on Martian dusty terrains may be an important process preventing soil induration and promoting dynamic phenomena (soil avalanching and fluidization and regolith gardening), maintaining a reservoir of micrometer size dust particles that are mobile and available for lifting. The discovery of this diurnal CO2 cycle represents an important step forward in our understanding of the way the Martian atmosphere interacts with the surface.

  2. Analysis of mRNA translation states in Arabidopsis over the diurnal cycle by polysome microarray.

    PubMed

    Missra, Anamika; von Arnim, Albrecht G

    2014-01-01

    Gene regulation at the level of translation occurs in response to environmental perturbation and is increasingly recognized as a factor affecting plant development. Despite extensive knowledge of transcriptional control, very little is known about translational regulation of genes in response to the daily light/dark cycles. Here we describe the experimental layout designed to address how the translation states of genes change at various times during a diurnal cycle in Arabidopsis thaliana seedlings. We have adopted a strategy combining sucrose-gradient profiling of ribosomes and high-throughput microarray analysis of the ribosome-associated mRNA to investigate the translational landscape of the Arabidopsis genome. This is a powerful technique that can be easily extended to study translation regulation in different genetic backgrounds and under various environmental conditions. PMID:24792050

  3. The diurnal cycle of rainfall over New Guinea in convection-permitting WRF simulations

    NASA Astrophysics Data System (ADS)

    Hassim, M. E. E.; Lane, T. P.; Grabowski, W. W.

    2015-07-01

    In this study, we examine the diurnal cycle of rainfall over New Guinea using a series of convection-permitting numerical simulations with the Weather Research and Forecasting (WRF) model. We focus our simulations on a period of suppressed regional-scale conditions (February 2010) during which local diurnal forcings are maximised. Additionally, we focus our study on the occurrence and dynamics of offshore propagating convective systems that contribute to the observed early-morning rainfall maximum north-east of New Guinea. In general, modelled diurnal precipitation shows good agreement with satellite-observed rainfall, albeit with some timing and intensity differences. The simulations also reproduce the occurrence and variability of overnight convection that propagate offshore as organised squall lines north-east of New Guinea. The occurrence of these offshore systems is largely controlled by background conditions. Days with offshore propagating convection have more middle tropospheric moisture, larger CAPE and greater low-level moisture convergence. Convection has similar characteristics over the terrain on days with and without offshore propagation. The offshore propagating convection manifests via a multi-stage evolutionary process. First, scattered convection over land, which is remnant of the daytime maximum, moves towards the coast and becomes re-organised near the region of coastal convergence associated with the land breeze. The convection then moves offshore in the form of a squall line at ~5 m s-1. In addition, cool anomalies associated with gravity waves generated by precipitating land convection propagate offshore at a dry hydrostatic gravity wave speed (of ~15 m s-1), and act to destabilise the coastal/offshore environment prior to the arrival of the squall line. Although the gravity wave does not appear to initiate the convection or control its propagation, it should contribute to its longevity and maintenance. The results highlight the importance of

  4. The diurnal cycle of rainfall over New Guinea in convection-permitting WRF simulations

    NASA Astrophysics Data System (ADS)

    Hassim, M. E. E.; Lane, T. P.; Grabowski, W. W.

    2016-01-01

    In this study, we examine the diurnal cycle of rainfall over New Guinea using a series of convection-permitting numerical simulations with the Weather Research and Forecasting (WRF) model. We focus our simulations on a period of suppressed regional-scale conditions (February 2010) during which local diurnal forcings are maximised. Additionally, we focus our study on the occurrence and dynamics of offshore-propagating convective systems that contribute to the observed early-morning rainfall maximum north-east of New Guinea.

    In general, modelled diurnal precipitation shows good agreement with satellite-observed rainfall, albeit with some timing and intensity differences. The simulations also reproduce the occurrence and variability of overnight convection that propagate offshore as organised squall lines north-east of New Guinea. The occurrence of these offshore systems is largely controlled by background conditions. Days with offshore-propagating convection have more middle tropospheric moisture, larger convective available potential energy, and greater low-level moisture convergence. Convection has similar characteristics over the terrain on days with and without offshore propagation.

    The offshore-propagating convection manifests via a multi-stage evolutionary process. First, scattered convection over land, which is remnant of the daytime maximum, moves towards the coast and becomes reorganised near the region of coastal convergence associated with the land breeze. The convection then moves offshore in the form of a squall line at ˜ 5 ms-1. In addition, cool anomalies associated with gravity waves generated by precipitating land convection propagate offshore at a dry hydrostatic gravity wave speed (of ˜ 15 ms-1) and act to destabilise the coastal/offshore environment prior to the arrival of the squall line. Although the gravity

  5. Diurnal changes of earthquake activity and geomagnetic Sq-variations

    NASA Astrophysics Data System (ADS)

    Duma, G.; Ruzhin, Y.

    Statistic analyses demonstrate that the probability of earthquake occurrence in many earthquake regions strongly depends on the time of day, that is on Local Time (e.g. Conrad, 1909, 1932; Shimshoni, 1971; Duma, 1997; Duma and Vilardo, 1998). This also applies to strong earthquake activity. Moreover, recent observations reveal an involvement of the regular diurnal variations of the Earth's magnetic field, commonly known as Sq-variations, in this geodynamic process of changing earthquake activity with the time of day (Duma, 1996, 1999). In the article it is attempted to quantify the forces which result from the interaction between the induced Sq-variation currents in the Earth's lithosphere and the regional Earth's magnetic field, in order to assess the influence on the tectonic stress field and on seismic activity. A reliable model is obtained, which indicates a high energy involved in this process. The effect of Sq-induction is compared with the results of the large scale electromagnetic experiment "Khibiny" (Velikhov, 1989), where a giant artificial current loop was activated in the Barents Sea.

  6. Effect of diurnal cycle in anthropogenic emissions on the vertical profile of black carbon over the Indian region

    NASA Astrophysics Data System (ADS)

    Govardhan, G.; Nanjundiah, R. S.; Satheesh, S.

    2013-12-01

    South Asian region is considered to be a regional hot spot for natural as well as anthropogenic aerosols viz. mineral dust, black carbon (BC), organic matter and so on. Vehicular and industrial emissions, forest fires, biomass burning for agricultural purposes and cooking are the main sources for the carbonaceous aerosols over the region. On the other hand, seasonal wind patterns over the region are the mainly responsible for the abundance of the mineral dust. Climate impact of large aerosol abundance on the regional climate has been a topic of interest during the last decade. The anthropogenic aerosols over the region have a diurnal variation owing to their sources (vehicular and industrial emissions). In this study, we have analysed the effect of diurnal cycle in emissions on the overall meteorology and the aerosols' concentrations over the region. We have used the version 3.3 of the online chemistry transport model WRF-Chem for this study. The model simulations for control runs (No diurnal emission cycle for anthropogenic aerosols i.e. constant emissions) and sensitivity runs (diurnal cycle for anthropogenic aerosols) are done for the 3 selected months of 2011 viz. May, October and December. From the results it has been observed that, the monthly mean vertical profile of BC over the selected 18 stations (urban+semi-urban+rural) is significantly affected by the inclusion of the diurnal cycle in the emissions. The changes in BC mass concentration are more than 60% over a few of the selected stations. The effect of diurnal cycle in emissions on the vertical profile of BC is more prominent in May than in October and December. In May, the noteworthy changes in BC mass concentrations occur within 3-8 km. Additionally, the effect of the diurnal cycle in emissions is seen on the vertical profile of BC over the selected oceanic regions as well. The back trajectory analysis of our model data with HYSPLIT model indicates the changes in the overall wind directions

  7. Studying the Diurnal Cycle of Convection Using a TRMM-Calibrated Infrared Rain Algorithm

    NASA Technical Reports Server (NTRS)

    Negri, Andrew J.; Adler, Robert F.; Huffman, George J.; Manyin, Michael

    2004-01-01

    The development of a satellite infrared (IR) technique for estimating convective and stratiform rainfall and its application in studying the diurnal variability of rainfall on a global scale is presented. The Convective-Stratiform Technique (CST), calibrated by coincident, physically retrieved rain rates from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), is applied over the global tropics. The technique makes use of the IR data from the TRMM Visible/Infrared Scanner (VIRS) before application to global geosynchronous satellite data. The calibrated CST technique has the advantages of high spatial resolution (4 km), filtering of non-raining cirrus clouds, and the stratification of the rainfall into its convective and stratiform components, the last being important for the calculation of vertical profiles of latent heating. The diurnal cycle of rainfall, as well as the division between convective and stratiform rainfall will be presented. The technique is validated using available data sets and compared to other global rainfall products such as Global Precipitation Climatology Project (GPCP) IR product, calibrated with TRMM Microwave Imager (TMI) data. Results from five years of PR data will show the global-tropical partitioning of convective and stratiform rainfall.

  8. Studying the Diurnal Cycle of Convection Using a TRMM-Calibrated Infrared Rain Algorithm

    NASA Technical Reports Server (NTRS)

    Negri, Andrew J.

    2005-01-01

    The development of a satellite infrared (IR) technique for estimating convective and stratiform rainfall and its application in studying the diurnal variability of rainfall on a global scale is presented. The Convective-Stratiform Technique (CST), calibrated by coincident, physically retrieved rain rates from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), is applied over the global tropics. The technique makes use of the IR data from the TRMM Visible/Infrared Scanner (VIRS) before application to global geosynchronous satellite data. The calibrated CST technique has the advantages of high spatial resolution (4 km), filtering of nonraining cirrus clouds, and the stratification of the rainfall into its convective and stratiform components, the last being important for the calculation of vertical profiles of latent heating. The diurnal cycle of rainfall, as well as the division between convective and Stratiform rainfall will be presented. The technique is validated using available data sets and compared to other global rainfall products such as Global Precipitation Climatology Project (GPCP) IR product, calibrated with TRMM Microwave Imager (TMI) data. Results from five years of PR data will show the global-tropical partitioning of convective and stratiform rainfall.

  9. On the Sensitivity of the Diurnal Cycle in the Amazon to Convective Intensity

    NASA Technical Reports Server (NTRS)

    Itterly, Kyle; Taylor, Patrick

    2015-01-01

    This presentation uses publicly available CERES and radiosonde data to investigate the sensitivity of thetropical convective diurnal cycle to atmosphere state. Averaging surface observations into regimes of convective intensitydefined by satellite shows great promise for physical understandingof convection.• Convective processes in the Amazon are highly variable seasonallyand locally.• Buoyancy/CIN more important JJA– Mesoscale/synoptic features easier to separate– Length/depth of buoyancy layer very important in DJF (EL).• Moisture more important DJF, esp. UTH– Humidity of lower atmosphere significantly impacts LTS, LCL and abilityfor parcels to reach LFC.• Lower level jet strength/direction important• Convective initiation correlated with LTS, LR, LTH, EL• Duration/Phase better correlated with humidity variables• Surface Flux amplitude well correlated with convection

  10. TransCom model simulations of hourly atmospheric CO2: Experimental overview and diurnal cycle results for 2002

    NASA Astrophysics Data System (ADS)

    Law, R. M.; Peters, W.; RöDenbeck, C.; Aulagnier, C.; Baker, I.; Bergmann, D. J.; Bousquet, P.; Brandt, J.; Bruhwiler, L.; Cameron-Smith, P. J.; Christensen, J. H.; Delage, F.; Denning, A. S.; Fan, S.; Geels, C.; Houweling, S.; Imasu, R.; Karstens, U.; Kawa, S. R.; Kleist, J.; Krol, M. C.; Lin, S.-J.; Lokupitiya, R.; Maki, T.; Maksyutov, S.; Niwa, Y.; Onishi, R.; Parazoo, N.; Patra, P. K.; Pieterse, G.; Rivier, L.; Satoh, M.; Serrar, S.; Taguchi, S.; Takigawa, M.; Vautard, R.; Vermeulen, A. T.; Zhu, Z.

    2008-09-01

    A forward atmospheric transport modeling experiment has been coordinated by the TransCom group to investigate synoptic and diurnal variations in CO2. Model simulations were run for biospheric, fossil, and air-sea exchange of CO2 and for SF6 and radon for 2000-2003. Twenty-five models or model variants participated in the comparison. Hourly concentration time series were submitted for 280 sites along with vertical profiles, fluxes, and meteorological variables at 100 sites. The submitted results have been analyzed for diurnal variations and are compared with observed CO2 in 2002. Mean summer diurnal cycles vary widely in amplitude across models. The choice of sampling location and model level account for part of the spread suggesting that representation errors in these types of models are potentially large. Despite the model spread, most models simulate the relative variation in diurnal amplitude between sites reasonably well. The modeled diurnal amplitude only shows a weak relationship with vertical resolution across models; differences in near-surface transport simulation appear to play a major role. Examples are also presented where there is evidence that the models show useful skill in simulating seasonal and synoptic changes in diurnal amplitude.

  11. Influence of topography and wind speed on the diurnal cycle of moist convection in an Idealized framework

    NASA Astrophysics Data System (ADS)

    Hassanzadeh, H.; Schmidli, J.; Schlemmer, L.; Schär, C.

    2012-04-01

    The influence of topography on the diurnal cycle of mid-latitude, summertime, moist convection is investigated in an idealized framework using cloud-resolving model with a horizontal grid spacing of 2 km. In this framework, the atmosphere is continuously relaxed towards prescribed reference profiles of temperature, specific humidity and wind speed. This relaxation mimics the influence of a steady large-scale flow. The strength of the relaxation varies with height. It is relatively strong in the stratosphere and upper troposphere (relaxation time is 2 days), but very weak in the lower troposphere. Apart from its influence on the mean environment, the relaxation has only a minimal influence on the diurnal evolution of the planetary boundary layer and moist convection. The simulations are run for 30 days. During the last 15 days a quasi-steady diurnal cycle is obtained, the diurnal equilibrium. Here, we investigate the influence of different topographies (mountain height and half-width) and wind profiles on the diurnal equilibrium evolution of clouds, precipitation and the associated net vertical fluxes of energy and water. As expected, in comparison to the simulation of flat terrain clouds and precipitation occur earlier over topography and total precipitation amounts are substantially increased. A particular focus will be on the analysis of the mountain effects as a function of the distance from the mountain (e.g. near-field and far-field effects).

  12. A comparison of the fine-scale structure of the diurnal cycle of tropical rain and lightning

    NASA Astrophysics Data System (ADS)

    Venugopal, V.; Virts, K.; Sukhatme, J.; Wallace, J. M.; Chattopadhyay, B.

    2016-03-01

    In this study, the fine-scale structure of the diurnal variability of ground-based lightning is systematically compared with satellite-based rain. At the outset, it is shown that tropical variability of lightning exhibits a prominent diurnal mode, much like rain. A comparison of the geographical distribution of the timing of the diurnal maximum shows that there is very good agreement between the two observables over continental and coastal regions throughout the tropics. Following this global tropical comparison, we focus on two regions, Borneo and equatorial South America, both of which show the interplay between oceanward and landward propagations of the phase of the diurnal maximum. Over Borneo, both rain and lightning clearly show a climatological cycle of "breathing in" (afternoon to early morning) and "breathing out" (morning to early afternoon). Over the equatorial east coast of South America, landward propagation is noticed in rain and lightning from early afternoon to early morning. Along the Pacific coast of South America, both rain and lightning show oceanward propagation. Though qualitatively consistent, over both regions the propagation is seen to extend further in rainfall. Additionally, given that lightning highlights vigorous convection, the timing of its diurnal maximum often precedes that of rainfall in the convective life cycle.

  13. How do changes in the Diurnal Cycle affect Bi-stability and Climate Sensitivity in the Habitable Zone?

    NASA Astrophysics Data System (ADS)

    Boschi, R.; Valerio, L.

    2013-09-01

    In this study we deal with the effect of varying the length of the diurnal cycle on its bi-stability properties. By using a general circulation model, PlaSim, we consider several values for the diurnal cycle, from tidally locked, to that of 1 Earth day. For each value of the diurnal cycle, we slowly modulate the solar constant between 1510 and 1000 Wm-2 and perform a hysteresis experiment. It is found that the width of the bi-stable region, i.e. the range of climate states - determined here by changes in S* - which support two climatic attractors, reduces when the diurnal cycle is increased in length and disappears - signifying the merging of both attractors - for climates with a diurnal cycle greater than 180 days. Crucial to the loss of bi-stability is the longitudinally asymmetric distribution of solar radiation, incident on the planet's surface, leading to the development of equatorial sea-ice. For diurnal cycles where bi-stability is found, the longitudinally asymmetric heating is sufficiently compensated for by the strength of the zonal winds and the rate of solar distribution, which redistribute heat and maintain the meridional temperature gradient across all longitudes. Conversely, for mono-stable regimes, the energy transport associated with zonal winds becomes insufficient to compensate for the increase in the length of the diurnal cycle, resulting in large zonal temperature gradients along the equatorial band. Furthermore, the results found here confirm and reenforce the robustness of those found in Boschi et al (2013), showing that, for climates which support bistability, it may be possible to parameterise variables such as the material entropy production and the meridional heat transport in terms of the surface and emission temperatures, within reasonably well defined upper and lower bounds, even when considering a wide range of planetary rotation speeds and changes to the infrared opacity. This paves the way for the possibility of practically deducing

  14. Modeling diurnal land temperature cycles over Los Angeles using downscaled GOES imagery

    NASA Astrophysics Data System (ADS)

    Weng, Qihao; Fu, Peng

    2014-11-01

    Land surface temperature is a key parameter for monitoring urban heat islands, assessing heat related risks, and estimating building energy consumption. These environmental issues are characterized by high temporal variability. A possible solution from the remote sensing perspective is to utilize geostationary satellites images, for instance, images from Geostationary Operational Environmental System (GOES) and Meteosat Second Generation (MSG). These satellite systems, however, with coarse spatial but high temporal resolution (sub-hourly imagery at 3-10 km resolution), often limit their usage to meteorological forecasting and global climate modeling. Therefore, how to develop efficient and effective methods to disaggregate these coarse resolution images to a proper scale suitable for regional and local studies need be explored. In this study, we propose a least square support vector machine (LSSVM) method to achieve the goal of downscaling of GOES image data to half-hourly 1-km LSTs by fusing it with MODIS data products and Shuttle Radar Topography Mission (SRTM) digital elevation data. The result of downscaling suggests that the proposed method successfully disaggregated GOES images to half-hourly 1-km LSTs with accuracy of approximately 2.5 K when validated against with MODIS LSTs at the same over-passing time. The synthetic LST datasets were further explored for monitoring of surface urban heat island (UHI) in the Los Angeles region by extracting key diurnal temperature cycle (DTC) parameters. It is found that the datasets and DTC derived parameters were more suitable for monitoring of daytime- other than nighttime-UHI. With the downscaled GOES 1-km LSTs, the diurnal temperature variations can well be characterized. An accuracy of about 2.5 K was achieved in terms of the fitted results at both 1 km and 5 km resolutions.

  15. Cloud frequency climatology at the Andes/Amazon transition: 1. Seasonal and diurnal cycles

    NASA Astrophysics Data System (ADS)

    Halladay, Kate; Malhi, Yadvinder; New, Mark

    2012-12-01

    Tropical montane regions present a complex local climate but one that may be very sensitive to local and global change. Therefore, it is important to assess their current climatological state, and to understand how the large-scale circulation may affect local-scale cloud patterns. We examine the cloud climatology of a tropical Andean montane region in the context of tropical South American climate in terms of seasonal/diurnal cycles using a corrected ISCCP (International Satellite Cloud Climatology Project) DX cloud product (1983-2008), MODIS (Moderate Resolution Imaging Spectroradiometer) MOD35 visible cloud flags (2000-2008) and ground-based cloud observations. Cloud climatologies were compared for three elevation zones: highlands (puna grassland), eastern slope (the montane forest) and lowlands. We found that in the dry season (JJA) the study area is part of a localized region of higher cloud frequency relative to other parts the eastern slope, and also relative to the adjacent highlands and lowlands. The highlands exhibited the greatest amplitude mean annual cycle of cloud frequency, with a minimum in June for all times of day. There were contrasts between the three zones with regard to the month in which the minimum cloud frequency occurs between different times of day. Higher lowland and eastern slope cloud frequencies compared with those on the puna in the early hours in the wet season suggest low-level convergence at lower elevations. Comparisons between satellite products show that ISCCP and MODIS produce very similar annual cycles although the absolute cloud frequencies are higher in ISCCP data.

  16. Diurnal cycles control the fate of contaminants at an Andean river confluence impacted by legacy mining

    NASA Astrophysics Data System (ADS)

    Pasten, P.; Guerra, P. A.; Simonson, K.; Bonilla, C.; Pizarro, G. E.; Escauriaza, C. R.; González, C.

    2014-12-01

    The importance of hydrologic-geochemical interactions in arid environments is a controlling factor in quality and quantity of water available for human consumption and agriculture. When acid drainage affects these watersheds, water quality is gravely degraded. Despite its effect on watersheds, the relationship between time changes in hydrological variables and water quality in arid regions has not been studied thoroughly. Temporal variations in acid drainage can control when the transport of toxic elements is increased. We performed field work at the Azufre River (pH 2, E.C~10.9 mS/cm) and Caracarani River (pH 8.7, E.C~1.2 mS/cm) confluence, located in the Northern Chilean Altiplano (at 4000 m asl). We registered stream flowrates (total flowrate~430 L/s), temperature and electric conductivity (E.C) hourly using in-stream data loggers during one year. We also measured turbidity and pH during one field survey at different distances from the junction, as a proxy of the formation of iron-aluminum particles that cycle trace elements in these environments. We found turbidity-pH diurnal cycles were caused by upstream hourly changes in upstream flowrate: when the Caracarani River flowrate reached its daily peak, particle formation occurred, while the dissolution of particles occurred when the Azufre River reached its maximum value. This last process occurred due to upstream freeze-thaw cycles. This study shows how the dynamics of natural confluences determines chemical transport. The formation of particles enriched in toxic elements can promote settling as a natural attenuation process, while their dissolution will produce their release and transport long distances downstream. It is important to consider time as an important variable in water quality monitoring and in water management infrastructure where pulses of contamination can have potentially negative effects in its use. Acknowledgements: Funding was provided by "Proyecto Fondecyt 1130936" and "CONICYT

  17. New Seasonal Shift in In-Stream Diurnal Nitrate Cycles Identified by Mining High-Frequency Data.

    PubMed

    Aubert, Alice H; Breuer, Lutz

    2016-01-01

    The recent development of in-situ monitoring devices, such as UV-spectrometers, makes the study of short-term stream chemistry variation relevant, especially the study of diurnal cycles, which are not yet fully understood. Our study is based on high-frequency data from an agricultural catchment (Studienlandschaft Schwingbachtal, Germany). We propose a novel approach, i.e. the combination of cluster analysis and Linear Discriminant Analysis, to mine from these data nitrate behavior patterns. As a result, we observe a seasonality of nitrate diurnal cycles, that differs from the most common cycle seasonality described in the literature, i.e. pre-dawn peaks in spring. Our cycles appear in summer and the maximum and minimum shift to a later time in late summer/autumn. This is observed both for water- and energy-limited years, thus potentially stressing the role of evapotranspiration. This concluding hypothesis on the role of evapotranspiration on nitrate stream concentration, which was obtained through data mining, broadens the perspective on the diurnal cycling of stream nitrate concentrations. PMID:27073838

  18. New Seasonal Shift in In-Stream Diurnal Nitrate Cycles Identified by Mining High-Frequency Data

    PubMed Central

    2016-01-01

    The recent development of in-situ monitoring devices, such as UV-spectrometers, makes the study of short-term stream chemistry variation relevant, especially the study of diurnal cycles, which are not yet fully understood. Our study is based on high-frequency data from an agricultural catchment (Studienlandschaft Schwingbachtal, Germany). We propose a novel approach, i.e. the combination of cluster analysis and Linear Discriminant Analysis, to mine from these data nitrate behavior patterns. As a result, we observe a seasonality of nitrate diurnal cycles, that differs from the most common cycle seasonality described in the literature, i.e. pre-dawn peaks in spring. Our cycles appear in summer and the maximum and minimum shift to a later time in late summer/autumn. This is observed both for water- and energy-limited years, thus potentially stressing the role of evapotranspiration. This concluding hypothesis on the role of evapotranspiration on nitrate stream concentration, which was obtained through data mining, broadens the perspective on the diurnal cycling of stream nitrate concentrations. PMID:27073838

  19. The diurnal water cycle at Curiosity: Role of exchange with the regolith

    NASA Astrophysics Data System (ADS)

    Savijärvi, Hannu; Harri, Ari-Matti; Kemppinen, Osku

    2016-02-01

    Hourly temperatures T, relative humidities RH and mass mixing ratios of moisture q at 1.6 m derived from the Mars Science Laboratory REMS-H and REMS-P measurements are shown for MSL sols 15-17 (Curiosity at Bradbury) and 80-82 (Curiosity at Rocknest). They are compared to column model simulations with and without adsorption to porous regolith. The observed mixing ratio is small at night (10-30 ppmm). It increases rapidly to 50-80 ppmm after sunrise and decreases slowly during the evening. The model gives a good account of the observed T and, with adsorption and realistic precipitable water content (PWC), reproduces the diurnal cycles of both RH and q relatively well. The suggested regolith thermal inertia is 300 tiu and porosity 35-40% for both sites. According to the simulations moisture is adsorbed and diffused to the cooling regolith in the evening from the lowest very stable air layer. It is then desorbed in the morning from the rapidly warming regolith and mixed throughout the growing convective boundary layer. Estimates of PWC based on night-time near-surface moistures (assuming an even distribution with height) might therefore be on the low side in areas of porous adsorbing regolith.

  20. Clouds, radiation, and the diurnal cycle of sea surface temperature in the tropical Western Pacific

    SciTech Connect

    Webster, P.J.; Clayson, C.A.; Curry, J.A.

    1996-04-01

    In the tropical Western Pacific (TWP) Ocean, the clouds and the cloud-radiation feedback can only be understood in the context of air/sea interactions and the ocean mixed layer. Considerable interest has been shown in attempting to explain why sea surface temperature (SST) rarely rises above 30{degrees}C, and gradients of the SST. For the most part, observational studies that address this issue have been conducted using monthly cloud and SST data, and the focus has been on intraseasonal and interannual time scales. For the unstable tropical atmosphere, using monthly averaged data misses a key feedback between clouds and SST that occurs on the cloud-SST coupling time scale, which was estimated to be 3-6 days for the unstable tropical atmosphere. This time scale is the time needed for a change in cloud properties, due to the change of ocean surface evaporation caused by SST variation, to feed back to the SST variation, to feed back to the SST through its effect on the surface heat flux. This paper addresses the relationship between clouds, surface radiation flux and SST of the TWP ocean over the diurnal cycle.

  1. Solar activity secular cycles

    NASA Astrophysics Data System (ADS)

    Kramynin, A. P.; Mordvinov, A. V.

    2013-12-01

    Long-term variations in solar activity secular cycles have been studied using a method for the expansion of reconstructed sunspot number series Sn( t) for 11400 years in terms of natural orthogonal functions. It has been established that three expansion components describe more than 98% of all Sn( t) variations. In this case, the contribution of the first expansion component is about 92%. The averaged form of the 88year secular cycle has been determined based on the form of the first expansion coordinate function. The quasi-periodicities modulating the secular cycle have been revealed based on the time function conjugate to the first function. The quasi-periodicities modulating the secular cycle coincide with those observed in the Sn( t) series spectrum. A change in the secular cycle form and the time variations in this form are described by the second and third expansion components, the contributions of which are about 4 and 2%, respectively. The variations in the steepness of the secular cycle branches are more pronounced in the 200-year cycle, and the secular cycle amplitude varies more evidently in the 2300-year cycle.

  2. Inter-annual Variability of Biomass Burning Aerosol Optical Depth in Southern Amazonia, and the Impact of These Aerosols on the Diurnal Cycle of Solar Flux Reduction

    NASA Astrophysics Data System (ADS)

    Eck, T. F.; Holben, B. N.; Schafer, J. S.; Artaxo, P.; Yamasoe, M. A.; Procopio, A. S.; Prins, E. M.; Feltz, J. M.; Smirnov, A.; Dubovik, O.; Reid, J. S.

    2002-12-01

    The inter-annual variability of the magnitude of biomass burning in southern Amazonia has been relatively large over the last decade. The extent of the burning in the latter half of a given dry season (July-October) depends largely on the rainfall amount and timing, with drought years exhibiting many more fires and smoke than average. Additionally, new regulations aimed at controlling burning may also affect inter-annual variability. We present measurements of aerosol optical depth (AOD) from biomass burning smoke as measured by AERONET sites in Rondonia and Mato Grosso from 1993-2002. These AOD measurements are shown to follow similar inter-annual variability as the fire counts determined by the multi-spectral radiance measurements obtained with GOES-8. However, the AOD at these sites exhibit relatively little diurnal variation despite a very large diurnal cycle in satellite detected fire counts. In order to quantify the changes in the diurnal cycle of solar flux reduction as a result of aerosol attenuation at the peak of the burning season, we model the diurnal cycle of total shortwave (SW; 300-4000 nm), photosynthetically active radiation (PAR; 400-700 nm), and Ultraviolet- A (UVA; 320-400 nm) fluxes in mid-September using the AERONET monthly average AOD measurements (AOD(550 nm) = 1.11). These average diurnal cycle flux reductions show significant temporal delays in the morning for equivalent flux levels in all three spectral bands, of ~50 min to 2 hr 15 min at mid-morning (midpoint between sunrise and solar noon). The largest time delays in flux occur in the UVA band and the smallest in the total SW broadband due to a rapid decrease in AOD as wavelength increases for the accumulation mode smoke aerosols. The time delays in solar flux have implications for possible delay of the onset of cumulus convection, the shortening of the photo-period when plants photosynthesize, and reduced time interval for UVA fluxes which may have implications for photochemical

  3. Diurnal biting activity and transmission of Onchocerca volvulus (Filariata: Onchocercidae) by Simulium yahense (Diptera: Simuliidae) in Liberia.

    PubMed

    Davis, J R; Wasserman, S S; Trpis, M

    1994-03-01

    To determine the influence of meterological factors on the diurnal biting cycle of Simulium yahense Vajime & Dunbar (a member of the Simulium damnosum Theoblad complex), we captured host-seeking females as they landed on the exposed lower legs of humans in the Harbel area of Liberia. Biting activity was greatest during the morning hours and was characterized by a unimodal harmonic curve. Although meteorological conditions had no decisive influence on the unimodal pattern of diurnal biting activity, hourly variation in the number of S. yahense captured at human bait was affected by meterological factors (i.e., the diurnal pattern of S. yahense biting activity is regulated by an internal clock, but the number of bits during any given hour is in response to meterological conditions). The transmission of Onchocerca volvulus (Leuckart) was highest during the morning hours when high transmission potentials were in phase with peak human activity and served to maintain the hyperendemicity of onchocerciasis in the Harbel area. PMID:8189413

  4. Photoperiodic control of circadian activity rhythms in diurnal rodents

    NASA Astrophysics Data System (ADS)

    Kramm, K. R.; Kramm, Deborah A.

    1980-03-01

    The responses of red squirrels (Tamiasciurus hudsonicus) and eastern chipmunks (Tamias striatus) to complete and skeleton light-dark (LD) cycles were compared. The skeletons, comprised of two 1-h pulses of light per day, effectively simulated the complete photoperiods in the squirrels, but not the chipmunks. Skeleton photoperiods greater than 12-h caused the chipmunks to shift activity from the longer to the shorter of the two intervals between the pulses. To interpret the mechanism of phase control, squirrels and chipmunks were kept in continuous darkness and exposed to 1-h light pulses every 10 days. The time-course of entrainment was also quantified. Both techniques produced light-response curves. The data suggest that the parametric and non-parametric contributions to entrainment are different in these two rodent species.

  5. Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: 2. Modeling results

    NASA Astrophysics Data System (ADS)

    Panday, Arnico K.; Prinn, Ronald G.; SchäR, Christoph

    2009-11-01

    After completing a 9-month field experiment studying air pollution and meteorology in the Kathmandu Valley, Nepal, we set up the mesoscale meteorological model MM5 to simulate the Kathmandu Valley's meteorology with a horizontal resolution of up to 1 km. After testing the model against available data, we used it to address specific questions to understand the factors that control the observed diurnal cycle of air pollution in this urban basin in the Himalayas. We studied the dynamics of the basin's nocturnal cold air pool, its dissipation in the morning, and the subsequent growth and decay of the mixed layer over the valley. During mornings, we found behavior common to large basins, with upslope flows and basin-center subsidence removing the nocturnal cold air pool. During afternoons the circulation in the Kathmandu Valley exhibited patterns common to plateaus, with cooler denser air originating over lower regions west of Kathmandu arriving through mountain passes and spreading across the basin floor, thereby reducing the mixed layer depth. We also examined the pathways of pollutant ventilation out of the valley. The bulk of the pollution ventilation takes place during the afternoon, when strong westerly winds blow in through the western passes of the valley, and the pollutants are rapidly carried out through passes on the east and south sides of the valley. In the evening, pollutants first accumulate near the surface, but then are lifted slightly when katabatic flows converge underneath. The elevated polluted layers are mixed back down in the morning, contributing to the morning pollution peak. Later in the morning a fraction of the valley's pollutants travels up the slopes of the valley rim mountains before the westerly winds begin.

  6. The Antarctic Krill Euphausia superba Shows Diurnal Cycles of Transcription under Natural Conditions

    PubMed Central

    Albiero, Alessandro; Sales, Gabriele; Millino, Caterina; Mazzotta, Gabriella M.; Bertolucci, Cristiano; Costa, Rodolfo

    2013-01-01

    Background Polar environments are characterized by extreme seasonal changes in day length, light intensity and spectrum, the extent of sea ice during the winter, and food availability. A key species of the Southern Ocean ecosystem, the Antarctic krill (Euphausia superba) has evolved rhythmic physiological and behavioral mechanisms to adapt to daily and seasonal changes. The molecular organization of the clockwork underlying these biological rhythms is, nevertheless, still only partially understood. Methodology/Principal Findings The genome sequence of the Antarctic krill is not yet available. A normalized cDNA library was produced and pyrosequenced in the attempt to identify large numbers of transcripts. All available E. superba sequences were then assembled to create the most complete existing oligonucleotide microarray platform with a total of 32,217 probes. Gene expression signatures of specimens collected in the Ross Sea at five different time points over a 24-hour cycle were defined, and 1,308 genes differentially expressed were identified. Of the corresponding transcripts, 609 showed a significant sinusoidal expression pattern; about 40% of these exibithed a 24-hour periodicity while the other 60% was characterized by a shorter (about 12-hour) rhythm. We assigned the differentially expressed genes to functional categories and noticed that those concerning translation, proteolysis, energy and metabolic process, redox regulation, visual transduction and stress response, which are most likely related to daily environmental changes, were significantly enriched. Two transcripts of peroxiredoxin, thought to represent the ancestral timekeeping system that evolved about 2.5 billion years ago, were also identified as were two isoforms of the EsRh1 opsin and two novel arrestin1 sequences involved in the visual transduction cascade. Conclusions Our work represents the first characterization of the krill diurnal transcriptome under natural conditions and provides a first

  7. Measuring diurnal cycles of plant transpiration fluxes in the Arctic with an automated clear chamber

    NASA Astrophysics Data System (ADS)

    Cohen, L. R.; Raz Yaseef, N.; Curtis, J. B.; Rahn, T. A.; Young, J. M.; Newman, B. D.

    2013-12-01

    Evapotranspiration is an important greenhouse gas and a major component of the hydrological cycle, but methodological challenges still limit our knowledge of this flux. Measuring evapotranspiration is even more difficult when aiming to partition plant transpiration and soil evaporation. Information on this process for arctic systems is very limited. In order to decrease this gap, our objective was to directly measure plant transpiration in Barrow, Alaska (71.3°N 156.7°W). A commercial system allows measuring carbon soil respiration fluxes with an automated clear chamber connected to an infrared gas-analyzer (Licor 8100), and while it simultaneously measures water concentrations, it is not calibrated to measure vapor fluxes. We calibrated the clear chamber against a previously established method based on a Licor 6400 soil chamber, and we developed a code to calculate fluxes. We performed laboratory comparisons in New Mexico and field comparisons in the Arctic, suggesting that this is a valid tool for a large range of climates. In the field we found a strong correlation between the two instruments with R2 of 0.79. Even with 24 hours of daylight in the Arctic, the system captures a clear diurnal transpiration flux, peaking at 0.9 mmol m-2 s-1 and showing no flux at the lowest points. This new method should be a powerful approach for long term measurements of specific vegetation types or surface features. Such Data can also be used to help understand controls on larger scale eddy covariance tower measurements of evapotranspiration.

  8. Modelling of the Thermodynamical Diurnal Cycle in the Lower Atmosphere: A Joint Evaluation of Four Contrasted Regimes in the Tropics Over Land

    NASA Astrophysics Data System (ADS)

    Couvreux, F.; Guichard, F.; Gounou, A.; Bouniol, D.; Peyrillé, P.; Köhler, M.

    2013-10-01

    The diurnal cycle is an important mode of variability in the Tropics that is not correctly predicted by numerical weather prediction models. The African Monsoon Multidisciplinary Analyses program provided for the first time a large dataset to document the diurnal cycle over West Africa. In order to assess the processes and mechanisms that are crucial for the representation of the diurnal cycle, four different regimes that characterize the varying conditions encountered over land along a surface-temperature gradient are selected. A single-column modelling framework is used in order to relate the features of the simulated diurnal cycle to physical processes in these four distinct cases. Particular attention is given to providing realistic initial and boundary conditions at the surface and in the atmosphere, enabling the use of independent data for the evaluation of the simulations. The study focuses on the simulation of the surface energy budget and low-level characteristics and analyzes the balance between cloud/surface/boundary-layer processes at the sub-diurnal time scale. The biases and drawbacks of the simulations are found to change along the temperature gradient but they always involve the representation of clouds. They also explain parts of the bias obtained with the same model when used in a less constrained configuration. Surface-atmosphere-cloud interactions arising at the sub-diurnal time scale are invoked to explain the distinct features of the low-level diurnal cycle observed over West Africa.

  9. (abstract) Variations in Polarimetric Backscatter of Saline Ice Grown Under Diurnal Thermal Cycling Condition

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Kong, J. A.; Hsu, C. C.; Ding, K. H.

    1995-01-01

    An experiment was carried out in January 1994 at the Geophysical Research Facility in the Cold Regions Research and Engineering Laboratory. To investigate effects on polarimetric scattering signatures of sea ice growth under diurnal temperature variations, an ice sheet was grown for 2.5 days for the thickness of 10 cm and a polarimetric radar operating at C-band was used to obtain backscattering data in conjunction with ice-characterization measurements. The ice sheet was grown in the late morning of January 19, 1994. The initial growth rate was slow due to high insolation and temperature. As the air temperature dropped during the night, the growth rate increased significantly. The air temperature changed drastically from about -10(deg)C to -35(deg)C between day and night. The temperature cycle was repeated during the next day and the growth rate varied in the same manner. The surface of the ice was partially covered by frost flowers and the areal coverage increased as the ice became thicker. Throughout the ice growth duration of 2.5 days, polarimetric backscatter data were collected at roughly every centimeter of ice growth. For each set of radar measurements of saline ice, a set of calibration measurements was carried out with trihedrial corner reflectors and a metallic sphere. Measured polarimetric backscattering coefficients of the ice sheet reveal a strong correlation between radar data and temperature variations. As the temperature increased (decreased), the backscatter increased (decreased) correspondingly. From the ice-characterization data, temperatures of the air, at the ice-air interface, and in the ice layer had the same variation trend. Another interesting experimental observation is that the salinity measured as a function of ice depth from a sample of 10-cm thich ice indicated that the salinity variations had a similar cycle as the temperature; i.e., the salinity profile recorded the history of the temperature variations. Characterization data of the

  10. Did Adult Diurnal Activity Influence the Evolution of Wing Morphology in Opoptera Butterflies?

    PubMed

    Penz, C M; Heine, K B

    2016-02-01

    The butterfly genus Opoptera includes eight species, three of which have diurnal habits while the others are crepuscular (the usual activity period for members of the tribe Brassolini). Although never measured in the field, it is presumed that diurnal Opoptera species potentially spend more time flying than their crepuscular relatives. If a shift to diurnal habits potentially leads to a higher level of activity and energy expenditure during flight, then selection should operate on increased aerodynamic and energetic efficiency, leading to changes in wing shape. Accordingly, we ask whether diurnal habits have influenced the evolution of wing morphology in Opoptera. Using phylogenetically independent contrasts and Wilcoxon rank sum tests, we confirmed our expectation that the wings of diurnal species have higher aspect ratios (ARs) and lower wing centroids (WCs) than crepuscular congeners. These wing shape characteristics are known to promote energy efficiency during flight. Three Opoptera wing morphotypes established a priori significantly differed in AR and WC values. The crepuscular, cloud forest dweller Opoptera staudingeri (Godman & Salvin) was exceptional in having an extended forewing tip and the highest AR and lowest WC within Opoptera, possibly to facilitate flight in a cooler environment. Our study is the first to investigate how butterfly wing morphology might evolve as a response to a behavioral shift in adult time of activity. PMID:26429581

  11. Assessing the Impacts of Wildfire Aerosols on the Diurnal Cycles of Stratocumulus Clouds over Southeast Atlantic Using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Lu, Z.; Liu, X.; Zhang, Z.

    2015-12-01

    Southern Africa is the world's largest emitter of biomass burning aerosols. The westward transport of these wildfire aerosols over the remote southeast Atlantic collocates with the Earth's major subtropical stratocumulus decks occurring in the marine boundary layer. Wildfire aerosols can significantly perturb the properties of marine stratocumulus through the microphysical effect (as CCN) and the radiative effect (as shortwave absorber); however, the relative importance of these two effects varies within 24 hours mainly due to the diurnal cycle of solar insolation. Given the fact that the strong diurnal cycles of stratocumulus are also largely controlled by the solar insolation, the wildfire aerosols are very likely to exert an additional significant effect on the diurnal cycles of stratocumulus. To prove this hypothesis, we examine the roles of wildfire aerosols in observed diurnal cycles of stratocumulus clouds using the WRF-Chem model in conjunction with satellite observations. Wildfire aerosol emissions are generated from fire radiative power detected by SEVIRI onboard Meteosat. The wildfire aerosols are treated as the internal mixture of OC, BC, and other inorganic components, and coupled with the microphysics and radiation schemes in WRF-Chem. We thoroughly compare the diurnal variations in modeled cloud properties, such as LWP and cloud fraction among 1) the case with both microphysical and radiative effects of wildfire aerosols (the reference case), 2) the case with only microphysical effect, and 3) the case with no wildfire aerosols. The differences in cloud properties are interpreted as the effects of wildfire aerosol. The wildfire aerosol, cloud, and radiation fields modeled by the reference case are validated against satellite observations, including MODIS aerosol optical depth, cloud fraction/LWP, CALIPSO aerosol-cloud overlapping frequency, and CERES radiative fluxes. The modeling results show that the microphysical effect of wildfire aerosols

  12. Diurnal cycle of precipitation over the British Isles in a 0.44° WRF multiphysics regional climate ensemble over the period 1990-1995

    NASA Astrophysics Data System (ADS)

    Mooney, P. A.; Mulligan, F. J.; Broderick, C.

    2016-02-01

    The diurnal cycle of precipitation is an important and fundamental cycle in Earth's climate system, yet many aspects of this cycle remain poorly understood. As a result climate models have struggled to accurately simulate the timing of the peak and the amplitude of the cycle. This has led to a large number of modelling studies on the diurnal cycle of precipitation which have focussed mainly on the influence of grid spacing and/or convective parameterizations. Results from these investigations have shown that, while grid spacing and convective parameterizations are important factors in the diurnal cycle, it cannot be fully explained by these factors and it must also be subject to other factors. In this study, we use the weather research and forecasting (WRF) model to investigate four of these other factors, namely the land surface model (LSM), microphysics, longwave radiation and planetary boundary layer in the case of the diurnal cycle of precipitation over the British Isles. We also compare their impact with the effect of two different convective schemes. We find that all simulations have two main problems: (1) there is a large bias (too much precipitation) in both summer and winter (+19 and +38 % respectively for the ensemble averages), and (2) WRF summer precipitation is dominated by a diurnal (24-h) component (~28 % of the mean precipitation) whereas the observations show a predominantly semidiurnal (12-h) component with a much smaller amplitude (~10 % of mean precipitation). The choice of LSM has a large influence on the simulated diurnal cycle in summer with the remaining physics schemes showing very little effect. The magnitude of the LSM effect in summer is as large as 35 % on average and up to 50 % at the peak of the cycle. While neither of the two LSMs examined here capture the harmonic content of the diurnal cycle of precipitation very well, we find that use of the RUC LSM results in better agreement with the observations compared with Noah.

  13. Seasonal Cycle of the Near-Surface Diurnal Wind Field Over the Bay of La Paz, Mexico

    NASA Astrophysics Data System (ADS)

    Turrent, Cuauhtémoc; Zaitsev, Oleg

    2014-05-01

    The results of numerical simulations of the troposphere over the Bay of La Paz, calculated for the months of January, April, July and October during the period 2006-2010 with the Weather Research and Forecast (WRF v3.5) regional model, are used to describe the seasonal features of the diurnal cycle of planetary boundary-layer winds. Two distinct near-surface diurnal flows with strong seasonal variability were identified: (1) a nocturnal and matutinal breeze directed from the subtropical Pacific Ocean, over the Baja California peninsula and the Bay of La Paz, into the Gulf of California that is associated with the regional sea-surface temperature difference between those two major water bodies; and (2) a mid to late afternoon onshore sea-breeze related to the peninsula's daily cycle of insolation heating that evolves with counter-clockwise rotation over the Bay of La Paz. The model results reveal the interaction over Baja California of opposing afternoon sea-breeze fronts that originate from the subtropical Pacific Ocean and the Gulf of California, with a convergence line forming over the peaks of the peninsula's topography and the associated presence of a closed vertical circulation cell over the Bay of La Paz and the adjacent Gulf. The collision of the opposing sea-breeze fronts over the narrow peninsula drives convection that is relatively weak due to the reduced heat source and only appears to produce precipitation sporadically. The spatial structure of the sea-breeze fronts over the Bay of La Paz region is complex due to shoreline curvature and nearby topographic features. A comparison of the numerical results with available meteorological near-surface observations indicates that the modelling methodology adequately reproduced the observed features of the seasonal variability of the local planetary boundary-layer diurnal wind cycle and confirms that the low-level atmospheric circulation over the Bay of La Paz is dominated by kinetic energy in the diurnal band

  14. Diurnal Variation in Gravity Wave Activity at Low and Middle Latitudes

    NASA Technical Reports Server (NTRS)

    Andrioli, V. F.; Fritts, D. C.; Batista, P. P.; Clemesha, B. R.; Janches, Diego

    2013-01-01

    We employ a modified composite day extension of the Hocking (2005) analysis method to study gravity wave (GW) activity in the mesosphere and lower thermosphere using 4 meteor radars spanning latitudes from 7deg S to 53.6deg S. Diurnal and semidiurnal modulations were observed in GW variances over all sites. Semidiurnal modulation with downward phase propagation was observed at lower latitudes mainly near the equinoxes. Diurnal modulations occur mainly near solstice and, except for the zonal component at Cariri (7deg S), do not exhibit downward phase propagation. At a higher latitude (SAAMER, 53.6deg S) these modulations are only observed in the meridional component where we can observe diurnal variation from March to May, and semidiurnal, during January, February, October (above 88 km) and November. Some of these modulations with downward phase progression correlate well with wind shear. When the wind shear is well correlated with the maximum of the variances the diurnal tide has its largest amplitudes, i.e., near equinox. Correlations exhibiting variations with tidal phases suggest significant GW-tidal interactions that have different characters depending on the tidal components and possible mean wind shears. Modulations that do not exhibit phase variations could be indicative of diurnal variations in GW sources.

  15. Diurnal cortisol amplitude and fronto-limbic activity in response to stressful stimuli.

    PubMed

    Cunningham-Bussel, Amy C; Root, James C; Butler, Tracy; Tuescher, Oliver; Pan, Hong; Epstein, Jane; Weisholtz, Daniel S; Pavony, Michelle; Silverman, Michael E; Goldstein, Martin S; Altemus, Margaret; Cloitre, Marylene; Ledoux, Joseph; McEwen, Bruce; Stern, Emily; Silbersweig, David

    2009-06-01

    The development and exacerbation of many psychiatric and neurologic conditions are associated with dysregulation of the hypothalamic pituitary adrenal (HPA) axis as measured by aberrant levels of cortisol secretion. Here we report on the relationship between the amplitude of diurnal cortisol secretion, measured across 3 typical days in 18 healthy individuals, and blood oxygen level dependant (BOLD) response in limbic fear/stress circuits, elicited by in-scanner presentation of emotionally negative stimuli, specifically, images of the World Trade Center (WTC) attack. Results indicate that subjects who secrete a greater amplitude of cortisol diurnally demonstrate less brain activation in limbic regions, including the amygdala and hippocampus/parahippocampus, and hypothalamus during exposure to traumatic WTC-related images. Such initial findings can begin to link our understanding, in humans, of the relationship between the diurnal amplitude of a hormone integral to the stress response, and those neuroanatomical regions that are implicated as both modulating and being modulated by that response. PMID:19135805

  16. Diurnal activities of the brown stink bug (Hemiptera: Pentatomidae) in and near tasseling corn fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The demand for effective management of the brown stink bug, Euschistus servus, in corn and other crops has been increasing in recent years. To identify when and where the stink bugs are most likely to occur for targeted insecticide application, diurnal activities of stink bugs in and near the field...

  17. Activity Cycles in Stars

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.

    2009-01-01

    Starspots and stellar activity can be detected in other stars using high precision photometric and spectrometric measurements. These observations have provided some surprises (starspots at the poles - sunspots are rarely seen poleward of 40 degrees) but more importantly they reveal behaviors that constrain our models of solar-stellar magnetic dynamos. The observations reveal variations in cycle characteristics that depend upon the stellar structure, convection zone dynamics, and rotation rate. In general, the more rapidly rotating stars are more active. However, for stars like the Sun, some are found to be inactive while nearly identical stars are found to be very active indicating that periods like the Sun's Maunder Minimum (an inactive period from 1645 to 1715) are characteristic of Sun-like stars.

  18. The Diurnal Cycle of the Boundary Layer, Convection, Clouds, and Surface Radiation in a Coastal Monsoon Environment (Darwin Australia)

    SciTech Connect

    May, Peter T.; Long, Charles N.; Protat, Alain

    2012-08-01

    The diurnal variation of convection and associated cloud and radiative properties remains a significant issue in global NWP and climate models. This study analyzes observed diurnal variability of convection in a coastal monsoonal environment examining the interaction of convective rain clouds, their associated cloud properties, and the impact on the surface radiation and corresponding boundary layer structure during periods where convection is suppressed or active on the large scale. The analysis uses data from the Tropical Warm Pool International Cloud Experiment (TWP-ICE) as well as routine measurements from the Australian Bureau of Meteorology and the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program. Both active monsoonal and large-scale suppressed (buildup and break) conditions are examined and demonstrate that the diurnal variation of rainfall is much larger during the break periods and the spatial distribution of rainfall is very different between the monsoon and break regimes. During the active monsoon the total net radiative input to the surface is decreased by more than 3 times the amount than during the break regime - this total radiative cloud forcing is found to be dominated by the shortwave (SW) cloud effects because of the much larger optical thicknesses and persistence of long-lasting anvils and cirrus cloud decks associated with the monsoon regime. These differences in monsoon versus break surface radiative energy contribute to low-level air temperature differences in the boundary layer over the land surfaces.

  19. The Impacts of the MPS on the Diurnal Cycle of convections in Meiyu Front

    NASA Astrophysics Data System (ADS)

    Sun, Jianhua; Zhang, Fuqing

    2013-04-01

    Cloud-resolving numerical experiments using the Weather Research and Forecast model are performed to examine the impact of a thermally-driven mountain-plain solenoid on the diurnal variation of precipitation along the Meiyu front over the Yangtze-Huang River Valleys of East China during 1-10 July 2007. The focus of analyses is on a 10-d simulation that used simplified flat terrains in the Valleys and initialized with the 10-d mean 0000-UTC global analysis with 10-d mean diurnal-varying-only lateral boundary conditions. Despite difference in the rainfall intensity and location, this experiment successfully simulated the observed diurnal variation and eastward propagation of rainfall evolution along the Meiyu front. It is found that the mountain-plains solenoid, along with the attendant nocturnal low-level jet, is primarily responsible for the midnight-to-earlier-morning rainfall enhancement along the Meiyu front. Diabatic heating from the enhanced nocturnal rainfall maximum subsequently leads to the formation of a mesoscale convective vortex that further organizes and amplifies moist convection while propagating eastward along the Meiyu front.

  20. Nitrogen homeostasis in man: influence of protein intake on the amplitude of diurnal cycling of body nitrogen.

    PubMed

    Price, G M; Halliday, D; Pacy, P J; Quevedo, M R; Millward, D J

    1994-01-01

    1. The diurnal nature of nitrogen (N) homoeostasis was investigated in adults fed increasing protein intakes. N balance was estimated during a 48 h period of consecutive 12 h periods of feeding hourly meals and fasting, after 12 days of adaptation to diets containing 0.36 +/- 0.01, 0.77 +/- 0.03, 1.59 +/- 0.08 and 2.31 +/- 0.65 g of protein day-1 kg-1. N losses were determined from measured urinary N excretion corrected for changes in the body urea pool, and estimated faecal and miscellaneous losses. [13C]Leucine and [2H5]phenylalanine balances were measured during a primed, continuous infusion of the two amino acids during the fasting and feeding phase on the second day. 2. Increasing fasting N losses were observed (47 +/- 7, 60 +/- 6, 95 +/- 15 and 140 +/- 36 mg day-1 kg-1) on the four intakes, with corresponding increasing fed gains of 8.2 +/- 3.9, 40.2 +/- 7.1, 112 +/- 24 and 180 +/- 56 mg day-1 kg-1. 3. Increasing fed-state amino acid gains with increasing protein intake were observed with both [13C]leucine and [2H5]phenylalanine, whereas increasing fasting amino acid losses were confirmed with [13C]leucine. 4. The N equivalent of the leucine oxidation rate was mostly in the range of 10-50% lower than expected from the N excretion rates. This may reflect the timing of the amino acid balance measurements and non-uniform rates of gain and loss throughout the diurnal cycle. 5. We conclude on the basis of both N and amino acid balances that the amplitude of the diurnal cycling of body protein N in human adults increases with increasing dietary protein intake. Thus one component of the protein requirement for N balance reflects a demand for repletion of fasting losses which increases with increasing habitual protein intake. PMID:8306557

  1. Sensor Measurements and Sediment Incubations Indicate Diurnal Redox Cycling Associate With Arsenic Mobilization at a Bangladeshi Rice Paddy

    NASA Astrophysics Data System (ADS)

    Lin, T.; Lin, C.; Ramanathan, N.; Neumann, R.; Harvey, C.; Jay, J.

    2007-12-01

    The presence of arsenic in the groundwater has led to the largest environmental poisoning in history; tens of millions of people in the Ganges Delta continue to drink groundwater that is dangerously contaminated with arsenic (As). Rice fields receive large loads of arsenic with irrigation water and provide recharge to the underlying aquifer. It is currently not known whether rice fields are a sink or source of arsenic in the hydrologic system. In the dry season, as As(III)-containing minerals are oxidized, As(V) is released and will adhere to Fe hydr(oxide) minerals. When sediments are inundated with water, reducing conditions will then drive reduction of Fe hydr(oxides) and release of As. We have been intensively studying a field site in Munshiganj, Bangladesh with extremely high levels of arsenic in groundwater (up to 1.2 mg/L). To better understand geochemical and microbial processes leading to As mobilization in surface sediment, we deployed sensors to take temporally dense measurements across our experimental rice paddy. Data collected in both 2006 and 2007 showed trends in geochemical parameters indicating that diurnal, possibly plant-induced, processes may be important. Over a two month period, nitrate concentrations decrease consistently each day as ammonium levels increase, presumably through temperature driven reductive processes. Nitrate concentrations in the subsurface then increase while ammonium levels decrease, possibly due to root oxygen leakage or rapid infiltration of oxygen rich surface water. Using sediment from the rice paddy and artificial irrigation water, laboratory microcosms were constructed to simulate the diurnal cycles observed at the field site. In carbon-ammended treatments, Fe and As cycling can occur on the order of days. Oscillations in redox conditions on diurnal as well as seasonal time scales may be important in the mobilization of arsenic into aquifers. By elucidating As mobilization mechanisms at an experimental rice paddy

  2. Space-Time Characteristics of Rainfall Diurnal Variations

    NASA Technical Reports Server (NTRS)

    Yang, Song; Kummerow, Chris; Olson, Bill; Smith, Eric A.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    The space-time features of rainfall diurnal variation of precipitation are systematically investigated by using the Tropical Rainfall Measuring Mission (TRMM) precipitation products retrieved from TRMM microwave imager (TMI), precipitation radar (PR) and TMI/PR combined algorithms. Results demonstrate that diurnal variability of precipitation is obvious over tropical regions. The dominant feature of rainfall diurnal cycle over, ocean is that there is consistent rainfall peak in early morning, while there is a consistent rainfall peak in mid-late afternoon over land. The seasonal variation on intensity of rainfall diurnal cycle is clearly evidenced. Horizontal distributions of rainfall diurnal variations indicate that there is a clearly early-morning peak with a secondary peak in the middle-late afternoon in ocean rainfall at latitudes dominated by large-scale convergence and deep convection. There is also an analogous early-morning peak in land rainfall along with a stronger afternoon peak forced by surface heating. Amplitude analysis shows that the patterns and its evolution of rainfall diurnal cycle are very close to rainfall distribution pattern and its evolution. These results indicate that rainfall diurnal variations are strongly associated with large-scale convective systems and climate weather systems. Phase studies clearly present the regional and seasonal features of rainfall diurnal activities. Further studies on convective and stratiform rainfall show different characteristics of diurnal cycles. Their spatial and temporal variations of convective and stratiform rainfall indicate that mechanisms for rainfall diurnal variations vary with time and space.

  3. Diurnal Human Activity and Introduced Species Affect Occurrence of Carnivores in a Human-Dominated Landscape.

    PubMed

    Moreira-Arce, Dario; Vergara, Pablo M; Boutin, Stan

    2015-01-01

    Diurnal human activity and domestic dogs in agro-forestry mosaics should theoretically modify the diurnal habitat use patterns of native carnivores, with these effects being scale-dependent. We combined intensive camera trapping data with Bayesian occurrence probability models to evaluate both diurnal and nocturnal patterns of space use by carnivores in a mosaic of land-use types in southern Chile. A total of eight carnivores species were recorded, including human-introduced dogs. During the day the most frequently detected species were the culpeo fox and the cougar. Conversely, during the night, the kodkod and chilla fox were the most detected species. The best supported models showed that native carnivores responded differently to landscape attributes and dogs depending on both the time of day as well as the spatial scale of landscape attributes. The positive effect of native forest cover at 250 m and 500 m radius buffers was stronger during the night for the Darwin's fox and cougar. Road density at 250 m scale negatively affected the diurnal occurrence of Darwin´s fox, whereas at 500 m scale roads had a stronger negative effect on the diurnal occurrence of Darwin´s foxes and cougars. A positive effect of road density on dog occurrence was evidenced during both night and day. Patch size had a positive effect on cougar occurrence during night whereas it affected negatively the occurrence of culpeo foxes and skunks during day. Dog occurrence had a negative effect on Darwin's fox occurrence during day-time and night-time, whereas its negative effect on the occurrence of cougar was evidenced only during day-time. Carnivore occurrences were not influenced by the proximity to a conservation area. Our results provided support for the hypothesis that diurnal changes to carnivore occurrence were associated with human and dog activity. Landscape planning in our study area should be focused in reducing both the levels of diurnal human activity in native forest remnants

  4. Diurnal Human Activity and Introduced Species Affect Occurrence of Carnivores in a Human-Dominated Landscape

    PubMed Central

    Moreira-Arce, Dario; Vergara, Pablo M.; Boutin, Stan

    2015-01-01

    Diurnal human activity and domestic dogs in agro-forestry mosaics should theoretically modify the diurnal habitat use patterns of native carnivores, with these effects being scale-dependent. We combined intensive camera trapping data with Bayesian occurrence probability models to evaluate both diurnal and nocturnal patterns of space use by carnivores in a mosaic of land-use types in southern Chile. A total of eight carnivores species were recorded, including human-introduced dogs. During the day the most frequently detected species were the culpeo fox and the cougar. Conversely, during the night, the kodkod and chilla fox were the most detected species. The best supported models showed that native carnivores responded differently to landscape attributes and dogs depending on both the time of day as well as the spatial scale of landscape attributes. The positive effect of native forest cover at 250m and 500 m radius buffers was stronger during the night for the Darwin's fox and cougar. Road density at 250m scale negatively affected the diurnal occurrence of Darwin´s fox, whereas at 500m scale roads had a stronger negative effect on the diurnal occurrence of Darwin´s foxes and cougars. A positive effect of road density on dog occurrence was evidenced during both night and day. Patch size had a positive effect on cougar occurrence during night whereas it affected negatively the occurrence of culpeo foxes and skunks during day. Dog occurrence had a negative effect on Darwin's fox occurrence during day-time and night-time, whereas its negative effect on the occurrence of cougar was evidenced only during day-time. Carnivore occurrences were not influenced by the proximity to a conservation area. Our results provided support for the hypothesis that diurnal changes to carnivore occurrence were associated with human and dog activity. Landscape planning in our study area should be focused in reducing both the levels of diurnal human activity in native forest remnants and

  5. Understanding the diurnal cycle in fluvial dissolved organic carbon - The interplay of in-stream residence time, day length and organic matter turnover

    NASA Astrophysics Data System (ADS)

    Worrall, F.; Howden, N. J. K.; Burt, T. P.

    2015-04-01

    There is increasing interest in characterising the diurnal fluctuation of stream solute concentrations because observed data series derived from spot samples may be highly subjective if such diurnal fluctuations are large. This can therefore lead to large uncertainties, bias or systematic errors in calculation of fluvial solute fluxes, depending upon the particular sampling regime. A simplistic approach would be to assume diurnal fluctuations are constant throughout the water year, but this study proposes diurnal cycles in stream water quality can only be interpreted in the context of stream residence time and changing day length. Three years of hourly dissolved organic carbon (DOC) concentration and flow data from the River Dee catchment (1674 km2) were analysed, and statistical analysis of the entire record shows there is no consistent diurnal cycle in the record. From the 3-year record (1095 days) there were only 96 diurnal cycles could be analysed. Cycles were quantified in terms of their: relative and absolute amplitude; duration; time to maximum concentration; asymmetry; percentile flow and in-stream residence time. The median diurnal cycle showed an amplitude that was 9.2% of the starting concentration; it was not significantly asymmetric; and occurred at the 19th percentile flow. The median DOC removal rate was 0.07 mg C/l/hr with an inter-quartile range of 0.052-0.100 mg C/l/hr. Results were interpreted as controlled by two, separate, zero-order kinetic rate laws, one for the day and one for the night. There was no single diurnal cycle present across the record, rather a number of different cycles controlled by the combination of in-stream residence time and exposure to contrasting light conditions. Over the 3-year period the average in-stream loss of DOC was 32%. The diurnal cycles evident in high resolution DOC data are interpretable, but require contextual information for their influence on in-stream processes to be understood or for them to be utilised.

  6. Wind speed response of marine non-precipitating stratocumulus clouds over a diurnal cycle in cloud-system resolving simulations

    DOE PAGESBeta

    Kazil, Jan; Feingold, Graham; Yamaguchi, Takanobu

    2016-05-12

    Observed and projected trends in large-scale wind speed over the oceans prompt the question: how do marine stratocumulus clouds and their radiative properties respond to changes in large-scale wind speed? Wind speed drives the surface fluxes of sensible heat, moisture, and momentum and thereby acts on cloud liquid water path (LWP) and cloud radiative properties. We present an investigation of the dynamical response of non-precipitating, overcast marine stratocumulus clouds to different wind speeds over the course of a diurnal cycle, all else equal. In cloud-system resolving simulations, we find that higher wind speed leads to faster boundary layer growth and strongermore » entrainment. The dynamical driver is enhanced buoyant production of turbulence kinetic energy (TKE) from latent heat release in cloud updrafts. LWP is enhanced during the night and in the morning at higher wind speed, and more strongly suppressed later in the day. Wind speed hence accentuates the diurnal LWP cycle by expanding the morning–afternoon contrast. The higher LWP at higher wind speed does not, however, enhance cloud top cooling because in clouds with LWP ⪆ 50 g m−2, longwave emissions are insensitive to LWP. This leads to the general conclusion that in sufficiently thick stratocumulus clouds, additional boundary layer growth and entrainment due to a boundary layer moistening arises by stronger production of TKE from latent heat release in cloud updrafts, rather than from enhanced longwave cooling. We find that large-scale wind modulates boundary layer decoupling. At nighttime and at low wind speed during daytime, it enhances decoupling in part by faster boundary layer growth and stronger entrainment and in part because shear from large-scale wind in the sub-cloud layer hinders vertical moisture transport between the surface and cloud base. With increasing wind speed, however, in decoupled daytime conditions, shear-driven circulation due to large-scale wind takes over

  7. Wind speed response of marine non-precipitating stratocumulus clouds over a diurnal cycle in cloud-system resolving simulations

    DOE PAGESBeta

    Kazil, Jan; Feingold, Graham; Yamaguchi, Takanobu

    2016-05-12

    Observed and projected trends in large-scale wind speed over the oceans prompt the question: how do marine stratocumulus clouds and their radiative properties respond to changes in large-scale wind speed? Wind speed drives the surface fluxes of sensible heat, moisture, and momentum and thereby acts on cloud liquid water path (LWP) and cloud radiative properties. We present an investigation of the dynamical response of non-precipitating, overcast marine stratocumulus clouds to different wind speeds over the course of a diurnal cycle, all else equal. In cloud-system resolving simulations, we find that higher wind speed leads to faster boundary layer growth and strongermore » entrainment. The dynamical driver is enhanced buoyant production of turbulence kinetic energy (TKE) from latent heat release in cloud updrafts. LWP is enhanced during the night and in the morning at higher wind speed, and more strongly suppressed later in the day. Wind speed hence accentuates the diurnal LWP cycle by expanding the morning–afternoon contrast. The higher LWP at higher wind speed does not, however, enhance cloud top cooling because in clouds with LWP ≳50 gm–2, longwave emissions are insensitive to LWP. This leads to the general conclusion that in sufficiently thick stratocumulus clouds, additional boundary layer growth and entrainment due to a boundary layer moistening arises by stronger production of TKE from latent heat release in cloud updrafts, rather than from enhanced longwave cooling. Here, we find that large-scale wind modulates boundary layer decoupling. At nighttime and at low wind speed during daytime, it enhances decoupling in part by faster boundary layer growth and stronger entrainment and in part because shear from large-scale wind in the sub-cloud layer hinders vertical moisture transport between the surface and cloud base. With increasing wind speed, however, in decoupled daytime conditions, shear-driven circulation due to large-scale wind takes over from

  8. Wind speed response of marine non-precipitating stratocumulus clouds over a diurnal cycle in cloud-system resolving simulations

    NASA Astrophysics Data System (ADS)

    Kazil, Jan; Feingold, Graham; Yamaguchi, Takanobu

    2016-05-01

    Observed and projected trends in large-scale wind speed over the oceans prompt the question: how do marine stratocumulus clouds and their radiative properties respond to changes in large-scale wind speed? Wind speed drives the surface fluxes of sensible heat, moisture, and momentum and thereby acts on cloud liquid water path (LWP) and cloud radiative properties. We present an investigation of the dynamical response of non-precipitating, overcast marine stratocumulus clouds to different wind speeds over the course of a diurnal cycle, all else equal. In cloud-system resolving simulations, we find that higher wind speed leads to faster boundary layer growth and stronger entrainment. The dynamical driver is enhanced buoyant production of turbulence kinetic energy (TKE) from latent heat release in cloud updrafts. LWP is enhanced during the night and in the morning at higher wind speed, and more strongly suppressed later in the day. Wind speed hence accentuates the diurnal LWP cycle by expanding the morning-afternoon contrast. The higher LWP at higher wind speed does not, however, enhance cloud top cooling because in clouds with LWP ⪆ 50 g m-2, longwave emissions are insensitive to LWP. This leads to the general conclusion that in sufficiently thick stratocumulus clouds, additional boundary layer growth and entrainment due to a boundary layer moistening arises by stronger production of TKE from latent heat release in cloud updrafts, rather than from enhanced longwave cooling. We find that large-scale wind modulates boundary layer decoupling. At nighttime and at low wind speed during daytime, it enhances decoupling in part by faster boundary layer growth and stronger entrainment and in part because shear from large-scale wind in the sub-cloud layer hinders vertical moisture transport between the surface and cloud base. With increasing wind speed, however, in decoupled daytime conditions, shear-driven circulation due to large-scale wind takes over from buoyancy

  9. Alcohol Usage and Abrupt Cessation Modulate Diurnal Activity

    PubMed Central

    Norrell, Stacy; Reyes-Vasquez, Cruz; Burau, Keith; Dafny, Nachum

    2010-01-01

    Alcohol has many effects throughout the body. The effect on circadian rhythms and the correlation of these effects to withdrawal effects of alcohol present interesting findings. By measuring 3 planes of activity of female Sprague-Dawley rats during alcohol usage and continuing study through the first two days following withdrawal of alcohol allow for the observation of a drastic modulation of the circadian pattern of activity. PMID:20615456

  10. Dynamic proteomic profiling of a unicellular cyanobacterium Cyanothece ATCC51142 across light-dark diurnal cycles

    PubMed Central

    2011-01-01

    Background Unicellular cyanobacteria of the genus Cyanothece are recognized for their ability to execute nitrogen (N2)-fixation in the dark and photosynthesis in the light. An understanding of these mechanistic processes in an integrated systems context should provide insights into how Cyanothece might be optimized for specialized environments and/or industrial purposes. Systems-wide dynamic proteomic profiling with mass spectrometry (MS) analysis should reveal fundamental insights into the control and regulation of these functions. Results To expand upon the current knowledge of protein expression patterns in Cyanothece ATCC51142, we performed quantitative proteomic analysis using partial ("unsaturated") metabolic labeling and high mass accuracy LC-MS analysis. This dynamic proteomic profiling identified 721 actively synthesized proteins with significant temporal changes in expression throughout the light-dark cycles, of which 425 proteins matched with previously characterized cycling transcripts. The remaining 296 proteins contained a cluster of proteins uniquely involved in DNA replication and repair, protein degradation, tRNA synthesis and modification, transport and binding, and regulatory functions. Functional classification of labeled proteins suggested that proteins involved in respiration and glycogen metabolism showed increased expression in the dark cycle together with nitrogenase, suggesting that N2-fixation is mediated by higher respiration and glycogen metabolism. Results indicated that Cyanothece ATCC51142 might utilize alternative pathways for carbon (C) and nitrogen (N) acquisition, particularly, aspartic acid and glutamate as substrates of C and N, respectively. Utilization of phosphoketolase (PHK) pathway for the conversion of xylulose-5P to pyruvate and acetyl-P likely constitutes an alternative strategy to compensate higher ATP and NADPH demand. Conclusion This study provides a deeper systems level insight into how Cyanothece ATCC51142

  11. Marine boundary layer over the subtropical southeast Pacific during VOCALS-REx - Part 1: Mean structure and diurnal cycle

    NASA Astrophysics Data System (ADS)

    Rahn, D. A.; Garreaud, R.

    2010-05-01

    Atmospheric subsidence over the subtropical southeast Pacific (SEP) leads to a low-level anticyclonic circulation, a cool sea surface and a cloud-topped marine boundary layer (MBL). Observations in this region from a major field campaign during October and November 2008, the VOCALS Regional Experiment, provide ample data to characterize the lower atmospheric features over the SEP. The observations are also useful to test the ability of an area-limited, high-resolution atmospheric model to simulate the SEP conditions. Observations and model-results (where appropriate) improve the characterization of the mean state (Part 1) and variability (Part 2) of the lower troposphere including circulation, MBL characteristics and the upsidence wave. Along 20° S the MBL is generally deeper offshore (1600 m at 85° W) but there is also considerable variability. MBL depth and variability decrease towards the coast and maximum inversion strength is detected between 74-76° W. Weather Research and Forecasting (WRF) simulations underestimate MBL height the most near the coast but improve offshore. Southeasterly trades prevail within the MBL although the wind speed decreases toward the coast. Above the MBL along the coast of Chile, flow is northerly, has a maximum at 3 km, and extends westward to ~74° W, apparently due to the mechanical blocking exerted by the Andes upon the westerly flow aloft. Mean MBL features along northern Chile (18-25° S) are remarkably similar (e.g., MBL depth just below 1 km) in spite of different SST. Observed diurnal cycles of the temperature at the coast and further offshore exhibit a number of conspicuous features that are consistent with the southwestward propagation of an upsidence wave initiated during late evening along the south Peru coast. Furthermore, the passage of the vertical motion results in either constructive or deconstructive interference with the radiatively-forced diurnal cycle of MBL depth. Interference is clearly seen in the soundings

  12. Dynamic proteomic profiling of a unicellular cyanobacterium Cyanothece ATCC51142 across light-dark diurnal cycles

    SciTech Connect

    Aryal, Uma K.; Stockel, Jana; Krovvidi, Ravi K.; Gritsenko, Marina A.; Monroe, Matthew E.; Moore, Ronald J.; Koppenaal, David W.; Smith, Richard D.; Pakrasi, Himadri B.; Jacobs, Jon M.

    2011-12-01

    Unicellular cyanobacteria of the genus Cyanothece are recognized for their ability to execute nitrogen (N2)-fixation in the dark and photosynthesis in the light. Systems-wide dynamic proteomic profiling with mass spectrometry (MS) analysis reveals fundamental insights into the control and regulation of these functions. To expand upon the current knowledge of protein expression patterns in Cyanothece ATCC51142, we performed quantitative proteomic analysis using partial ("unsaturated") metabolic labeling and high mass accuracy LC-MS analysis. This dynamic proteomic profiling identified 721 actively synthesized proteins with significant temporal changes in expression throughout the light-dark cycles, of which 425 proteins matched with previously characterized cycling transcripts. The remaining 296 proteins contained a cluster of proteins uniquely involved in DNA replication and repair, protein degradation, tRNA synthesis and modification, transport and binding, and regulatory functions. Analysis of protein functions revealed that the expression of nitrogenase in the dark is mediated by higher respiration and glycogen metabolism. We have also shown that Cyanothece ATCC51142 utilizes alternative pathways for carbon (C) and nitrogen (N) acquisition, particularly, aspartic acid and glutamate as substrates of C and N, respectively. Utilization of phosphoketolase (PHK) pathway for the conversion of xylulose-5P to pyruvate and acetyl-P likely constitutes an alternative strategy to compensate higher ATP and NADPH demand. In conclusion, this study provides a deeper insight into how Cyanothece ATCC51142 modulates cellular functions to accommodate photosynthesis and N2-fixation within the single cell.

  13. Analysis of water-soluble ions and their precursor gases over diurnal cycle

    NASA Astrophysics Data System (ADS)

    Shon, Zang-Ho; Ghosh, Samik; Kim, Ki-Hyun; Song, Sang-Keun; Jung, Kweon; Kim, Nam-Jin

    2013-10-01

    A detailed description of an interactive relationship is made between water-soluble ionic components in PM2.5 and their precursor gases using the hourly resolution data measured at an urban monitoring site in Seoul during the year of 2010. Their diurnal variability was found to be correlated with their precursor gases (HNO3 and NH3). In the case of NO3- and NH4+, a close similarity was seen in their diurnal trends, especially during spring. There were no noticeable differences in the formation pathway of NO3-, SO42- , and NH4+ aerosols between day and night. For NO3- formation, heterogeneous hydrolysis of N2O5 might play a significant role in the nighttime enhancement of the oxidation rate. In addition, the concentrations of major anions (e.g. NO3-, SO42- , and Cl-) exhibited highly diverse seasonal patterns with their maximum values occurring in spring, summer, and winter, respectively. The overall results of this study suggest that the formation pathway of NO3- and SO42- aerosols should be regulated by a competing relationship between the NH3-lean (spring and winter) and NH3-rich conditions (summer and fall).

  14. Seasonal and diurnal cycles of 0.25-2.5 μm aerosol fluxes over urban Stockholm, Sweden

    NASA Astrophysics Data System (ADS)

    Vogt, M.; Nilsson, E. D.; Ahlm, L.; Mártensson, E. M.; Johansson, C.

    2011-11-01

    Size resolved aerosol and gas fluxes were measured in Stockholm from 1 April 2008 to 15 April 2009 over both urban and green sectors. CO2 and H2O fluxes peaked in daytime for all seasons. CO2 concentrations peaked in winter. Due to vegetation influence the CO2 fluxes had different diurnal cycles and magnitude in the two sectors. In the urban sector, CO2 fluxes indicated a net source. The sector dominated by residential areas and green spaces had its highest aerosol fluxes in winter. In spring, super micrometer concentrations for both sectors were significantly higher, as were the urban sector rush hour fluxes. The submicrometer aerosol fluxes had a similar diurnal pattern with daytime maxima for all seasons. This suggests that only the super micrometer aerosol emissions are dependent on season. During spring there was a clear difference in super micrometer fluxes between wet and dry streets. Our direct flux measurements have improved the understanding of the processes behind these aerosol emissions. They support the hypothesis that the spring peak in aerosol emissions are due to road dust, produced during the winter, but not released in large quantities until the roads dry up during spring, and explain why Stockholm has problems meeting the EU directive for aerosol mass (PM10).

  15. Seasonal and diurnal cycles of ammonia, nitrous acid and nitric acid at a forest site in Finland

    NASA Astrophysics Data System (ADS)

    Virkkula, A.; Makkonen, U.; Mäntykenttä, J.; Hakola, H.

    2012-04-01

    Background In July - August 2010 a large campaign "Hyytiälä United Measurements of Photochemistry and Particles in Air - Comprehensive Organic Precursor Emission Concentration 2010 (HUMPPA - COPEC-10)", was conducted in a boreal forest at the SMEAR II station in Hyytiälä, southwestern central Finland. The general goal was to study links between gas phase oxidation chemistry and particle properties and processes. The Finnish Meteorological Institute contributed to the campaign with an on-line analyzer MARGA 2S (Ten Brink et al., 2007) for semi-continuous (1-hr time resolution) measurement of water-soluble gases and ions. Concentrations of gases (HCl, HNO3, HNO2, NH3, SO2) and major ions in particles (Cl, NO3, SO4, NH4, Na, K, Mg, Ca) were measured in two size fractions: PM2.5 and PM10. The MARGA was kept running at SMEAR II also after the campaign. Here we discuss data collected until 30 April, 2011, and restrict the analysis to the nitrogen-containing gases. Ammonia plays a key role in neutralizing acidic atmospheric compounds and in aerosol formation. The concentration of semi-volatile aerosol species such as ammonium nitrate and ammonium chloride is strongly dependent on the gas phase precursors, NH3, HNO3 and HCl. HONO is of atmospheric importance due to its expected significant contribution to the production of OH radicals. Results and discussion The median concentrations of ammonia (NH3), nitrous acid (HONO) and nitric acid (HNO3) during whole period of 21 June 2010 - 30 April 2011 were 85, 54, and 57 ppt, respectively. The seasonal cycle was such that in summer the concentrations of all of these gases were the highest, the respective medians were 356, 70, and 81 ppt in June 21 - August 12, and lowest in winter (December - February), the respective medians were 38, 54, and 52 ppt. A very clear diurnal cycle of all these gases was observed, especially in July. In December there were no cyclic diurnal variation of these but in spring, especially in April the

  16. Marine boundary layer over the subtropical southeast Pacific during VOCALS-REx - Part 1: Mean structure and diurnal cycle

    NASA Astrophysics Data System (ADS)

    Rahn, D. A.; Garreaud, R. D.

    2009-12-01

    Atmospheric subsidence over the subtropical southeast Pacific (SEP) leads to a low-level anticyclonic circulation, a cool sea surface and a cloud-topped marine boundary layer (MBL). Observations in this region from a major field campaign during October and November 2008, the VOCALS Regional Experiment, provide ample data to characterize the lower atmospheric features over the SEP. The observations are also useful to test the ability of an area-limited, high-resolution atmospheric model to simulate the SEP conditions. Observations and model-results (where appropriate) improve the characterization of the mean state (Part 1) and variability (Part 2) of the lower troposphere including circulation, MBL characteristics and the upsidence wave. Along 20° S the MBL is generally deeper offshore (1600 m at 85° W) but there is also considerable variability. MBL depth and variability decrease towards the coast and maximum inversion strength is detected between 74-76° W. Southeasterly trades prevail within the MBL although the wind speed decreases toward the coast. Above the MBL along the coast of Chile, flow is northerly, has a maximum at 3 km, and extends westward to ~74° W, apparently due to the mechanical blocking exerted by the Andes upon the westerly flow aloft. Mean MBL features along northern Chile (18-25° S) are remarkably similar (e.g., MBL depth just below 1 km) in spite of different SST. Observed diurnal cycles of the temperature at the coast and further offshore exhibit a number of conspicuous features that are consistent with the southwestward propagation of an upsidence wave initiated during late evening along the south Peru coast. Furthermore, the passage of the vertical motion results in either constructive or deconstructive interference with the radiatively-forced diurnal cycle of MBL depth.

  17. Diurnal cycle and multi-decadal trend of formaldehyde in the remote atmosphere near 46° N

    NASA Astrophysics Data System (ADS)

    Franco, B.; Marais, E. A.; Bovy, B.; Bader, W.; Lejeune, B.; Roland, G.; Servais, C.; Mahieu, E.

    2015-11-01

    Only very few long-term trends of formaldehyde (HCHO) exist. Furthermore, many uncertainties remain as to its diurnal cycle, representing a large short-term variability superimposed on seasonal and inter-annual variations that should be accounted for when comparing ground-based observations to e.g., model results. In this study, we derive a multi-decadal time series (January 1988-June 2015) of HCHO total columns from ground-based high-resolution Fourier transform infrared (FTIR) solar spectra recorded at the high-altitude station of Jungfraujoch (Swiss Alps, 46.5° N, 8.0° E, 3580 m a.s.l.), allowing for the characterization of the mid-latitudinal atmosphere for background conditions. First we investigate the HCHO diurnal variation, peaking around noontime and mainly driven by the intra-day insolation modulation and methane (CH4) oxidation. We also characterize quantitatively the diurnal cycles by adjusting a parametric model to the observations, which links the daytime to the HCHO columns according to the monthly intra-day regimes. It is then employed to scale all the individual FTIR measurements on a given daytime in order to remove the effect of the intra-day modulation for improving the trend determination and the comparison with HCHO columns simulated by the state-of-the-art chemical transport model GEOS-Chem v9-02. Such a parametric model will be useful to scale the Jungfraujoch HCHO columns on satellite overpass times in the framework of future calibration/validation efforts of space borne sensors. GEOS-Chem sensitivity tests suggest then that the seasonal and inter-annual HCHO column variations above Jungfraujoch are predominantly led by the atmospheric CH4 oxidation, with a maximum contribution of 25 % from the anthropogenic non-methane volatile organic compound precursors during wintertime. Finally, trend analysis of the so-scaled 27 year FTIR time series reveals a long-term evolution of the HCHO columns in the remote troposphere to be related with the

  18. Diurnal cycle and multi-decadal trend of formaldehyde in the remote atmosphere near 46° N

    NASA Astrophysics Data System (ADS)

    Franco, Bruno; Marais, Eloise A.; Bovy, Benoît; Bader, Whitney; Lejeune, Bernard; Roland, Ginette; Servais, Christian; Mahieu, Emmanuel

    2016-03-01

    Only very few long-term records of formaldehyde (HCHO) exist that are suitable for trend analysis. Furthermore, many uncertainties remain as to its diurnal cycle, representing a large short-term variability superimposed on seasonal and inter-annual variations that should be accounted for when comparing ground-based observations to, e.g., model results. In this study, we derive a multi-decadal time series (January 1988-June 2015) of HCHO total columns from ground-based high-resolution Fourier transform infrared (FTIR) solar spectra recorded at the high-altitude station of Jungfraujoch (Swiss Alps, 46.5° N, 8.0° E, 3580 m a. s. l. ), allowing for the characterization of the mid-latitudinal atmosphere for background conditions. First we investigate the HCHO diurnal variation, peaking around noontime and mainly driven by the intra-day insolation modulation and methane (CH4) oxidation. We also characterize quantitatively the diurnal cycles by adjusting a parametric model to the observations, which links the daytime to the HCHO columns according to the monthly intra-day regimes. It is then employed to scale all the individual FTIR measurements on a given daytime in order to remove the effect of the intra-day modulation for improving the trend determination and the comparison with HCHO columns simulated by the state-of-the-art GEOS-Chem v9-02 chemical transport model. Such a parametric model will be useful to scale the Jungfraujoch HCHO columns on satellite overpass times in the framework of future calibration/validation efforts of space-borne sensors. GEOS-Chem sensitivity tests suggest then that the seasonal and inter-annual HCHO column variations above Jungfraujoch are predominantly led by the atmospheric CH4 oxidation, with a maximum contribution of 25 % from the anthropogenic non-methane volatile organic compound precursors during wintertime. Finally, trend analysis of the so-scaled 27-year FTIR time series reveals a long-term evolution of the HCHO columns in the

  19. Time to pay attention: attentional performance time-stamped prefrontal cholinergic activation, diurnality and performance

    PubMed Central

    Paolone, Giovanna; Lee, Theresa M.; Sarter, Martin

    2012-01-01

    Although the impairments in cognitive performance that result from shifting or disrupting daily rhythms have been demonstrated, the neuronal mechanisms that optimize fixed time daily performance are poorly understood. We previously demonstrated that daily practice of a sustained attention task (SAT) evokes a diurnal activity pattern in rats. Here we report that SAT practice at a fixed time produced practice time-stamped increases in prefrontal cholinergic neurotransmission that persisted after SAT practice was terminated and in a different environment. SAT time-stamped cholinergic activation occurred irrespective of whether the SAT was practiced during the light or dark phase or in constant light conditions. In contrast, prior daily practice of an operant schedule of reinforcement, albeit generating more rewards and lever presses per session than the SAT, neither activated the cholinergic system nor affected the animals' nocturnal activity pattern. Likewise, food-restricted animals exhibited strong food anticipatory activity (FAA) and attenuated activity during the dark period but FAA was not associated with increases in prefrontal cholinergic activity. Removal of cholinergic neurons impaired SAT performance and facilitated the reemergence of nocturnality. Shifting SAT practice away from a fixed time resulted in significantly lower performance. In conclusion, these experiments demonstrated that fixed time, daily practice of a task assessing attention generates a precisely practice time-stamped activation of the cortical cholinergic input system. Time-stamped cholinergic activation benefits fixed time performance and, if practiced during the light phase, contributes to a diurnal activity pattern. PMID:22933795

  20. Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: Observations

    NASA Astrophysics Data System (ADS)

    Panday, Arnico K.; Prinn, Ronald G.

    2009-05-01

    During the dry season of 2004-2005 we carried out field measurements of air pollution and meteorology in the Kathmandu Valley, Nepal, a bowl-shaped urban basin in the Himalayan foothills of Nepal. We measured the trace gases carbon monoxide (CO) and ozone (O3) and particulates (PM10), as well as meteorological variables. In our field observations we noted a very regular pattern of morning and evening peaks in CO and PM10 occurring daily in the valley bottom, interspersed with low values in the afternoons and at night. This pattern occurred even on days with unusual timing of emissions and was influenced by the timing of ventilation from the valley. Meteorological variables showed great day-to-day similarity, with a strong westerly wind blowing through the valley from late morning until dusk. We found that the air mass on nearby mountaintops was disconnected from pollution within the valley during the night, but received significant pollution during the morning, when up-slope flows began. At a pass on the western edge of the valley we found a diurnal switch in wind direction, with an inflow from late morning until late evening, and an outflow during the rest of the time. We found that part of the morning peak in pollution was caused by recirculation of pollutants emitted the night before, which spend the night in elevated layers over the valley.

  1. Impact of the ocean diurnal cycle on the intraseasonnal variability of Sea Surface Temperatures in the mid-latitudes Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Guemas, V.; Salas-Mélia, D.; Kageyama, M.; Giordani, H.; Voldoire, A.

    2009-04-01

    Some recent studies have shown that the ocean diurnal cycle could increase the intraseasonal variability of the Sea Surface Temperatures (SST) in the tropics (Shinoda and Hendon, 1998; Bernie et al, 2005; Shinoda, 2005). This study aims at extending these analyses to the mid-latitudes. To conduct these analyses, the CNRMOM1D 1-dimensional ocean model is forced with ERA40 reanalysis data with a 1 hour frequency in solar heat flux ( 6h hours for the other forcing fields ). The turbulent vertical mixing scheme (Gaspar et al., 1988) is based on the parameterisation of the second-order turbulent moments expressed as a function of the turbulent kinetic energy. The model has 124 vertical levels with a vertical resolution of 1m near the surface and 500m at the bottom. This high vertical resolution combined with a high temporal forcing resolution allows to simulate a realistic diurnal cycle of the oceanic upper-layers. This experiment is compared with one forced on a daily time-step. By comparing both experiments, the impact of the ocean diurnal cycle on the intraseasonnal variability of sea surface temperature anomalies is assessed. We show that the phase of the SST variability is affected and this impact is strongly associated with the non-linear interactions between the diurnal cycle in mixed layer depth and surface forcings.

  2. Wind speed response of marine non-precipitating stratocumulus clouds over a diurnal cycle in cloud-system resolving simulations

    NASA Astrophysics Data System (ADS)

    Kazil, J.; Feingold, G.; Yamaguchi, T.

    2015-10-01

    Observed and projected trends in large scale wind speed over the oceans prompt the question: how might marine stratocumulus clouds and their radiative properties respond to future changes in large scale wind speed? Wind speed drives the surface fluxes of sensible heat, moisture, and momentum, and thereby acts on cloud liquid water path (LWP) and cloud radiative properties. We present an investigation of the dynamical response of non-precipitating, overcast marine stratocumulus clouds to different wind speeds, all else equal. In cloud-system resolving simulations, we find that higher wind speed leads to faster boundary layer growth and stronger entrainment. The dynamical driver is enhanced buoyant production of turbulence kinetic energy (TKE) from latent heat release in cloud updrafts. LWP is enhanced during the night and in the morning at higher wind speed, and more strongly suppressed later in the day. Wind speed hence accentuates the diurnal LWP cycle by expanding the morning - afternoon contrast. The higher LWP at higher wind speed does not, however, enhance cloud top cooling because in clouds with LWP ⪆ 50 g m-2, long wave emissions are very insensitive to LWP. This leads to the more general conclusion that in sufficiently thick stratocumulus clouds, additional boundary layer growth and entrainment due to a boundary layer moistening arises by stronger production of TKE from latent heat release in cloud updrafts, rather than from enhanced longwave cooling. We find furthermore that large scale wind modulates boundary layer decoupling. At nighttime and at low wind speed during daytime, it enhances decoupling in part by faster boundary layer growth and stronger entrainment, and in part because circulation driven by shear from large scale wind in the sub-cloud layer hinders vertical moisture transport between the surface and cloud base. With increasing wind speed, however, in decoupled daytime conditions, shear-driven circulation due to large scale wind

  3. Seasonal thermogenic acclimation of diurnally and nocturnally active desert spiny mice.

    PubMed

    Kronfeld-Schor, N; Haim, A; Dayan, T; Zisapel, N; Klingenspor, M; Heldmaier, G

    2000-01-01

    Diurnally active golden spiny mice (Acomys russatus) and nocturnal common spiny mice (Acomys cahirinus) coexist in hot rocky deserts of Israel. Diurnal and nocturnal activities expose these species to different climatic conditions. Nonshivering thermogenesis (NST) capacity of individuals of both species immediately upon removal from the field exhibited seasonal changes, with no significant interspecific difference. Colony-reared mice of either species transferred in the laboratory from long to short photoperiod increased NST capacity, though to a lesser extent than observed in the seasonal acclimatization. The underlying biochemical mechanisms of short photoperiod acclimation differed between the species. In both Cytochrome-c oxidase (Cox) activity was higher in short as compared to long photoperiod. In short-photoperiod-acclimated A. cahirinus uncoupling protein (UCP) content in brown adipose tissue (BAT) was significantly higher than in long photoperiod, while in A. russatus there was no significant change. In A. russatus there was a significant increase in lipoprotein lipase (LPL) activity in BAT in short-photoperiod-acclimated individuals, while in A. cahirinus LPL activity was high under both acclimations. The low LPL activity in brown adipose tissue of desert-adapted A. russatus may facilitate lipid uptake in white adipose tissue, an advantage in desert conditions where food is scarce and irregularly distributed in space and time. PMID:10685905

  4. Nocturnal activity of a "diurnal" species, the northern chamois, in a predator-free Alpine area.

    PubMed

    Carnevali, Lucilla; Lovari, Sandro; Monaco, Andrea; Mori, Emiliano

    2016-05-01

    The reduction of predation risk is widely considered a major factor affecting the nocturnal activity of mammals. Furthermore, on precipitous mountain terrain, moving in very poor light conditions should be avoided by animals with no special eyesight adaptation to darkness. The Northern chamois Rupicapra rupicapra has been for long considered as a diurnal species, with occasional nocturnal movements. For the first time, we have quantified the nocturnal activity of 21 radiotagged female chamois from the Italian Eastern Alps (Paneveggio-Pale di San Martino Natural Park), continuously monitored for two years from sunset to sunrise, with 24h tracking sessions carried out for six months. Large predators were not present in the study site. Despite their mainly diurnal activity pattern, peaks of nocturnal movements were detected throughout the year. The least proportion of active night fixes occurred in January and in July, while the most were in April and in October. The greater nocturnal activity in the warm months compared to cold periods, was probably due to frozen snow cover reducing nocturnal movements. Movements were mainly concentrated in bright moonlight nights, possibly because of the absence of large predators, but more likely because of increased visibility. Changes in activity levels throughout the year may also reflect changes in energy requirements of Northern chamois. PMID:27012888

  5. Modeling the diurnal cycle of conserved and reactive species in the convective boundary layer using SOMCRUS

    NASA Astrophysics Data System (ADS)

    Lenschow, Donald H.; Gurarie, David; Patton, Edward G.

    2016-03-01

    We have developed a one-dimensional second-order closure numerical model to study the vertical turbulent transport of trace reactive species in the convective (daytime) planetary boundary layer (CBL), which we call the Second-Order Model for Conserved and Reactive Unsteady Scalars (SOMCRUS). The temporal variation of the CBL depth is calculated using a simple mixed-layer model with a constant entrainment coefficient and zero-order discontinuity at the CBL top. We then calculate time-varying continuous profiles of mean concentrations and vertical turbulent fluxes, variances, and covariances of both conserved and chemically reactive scalars in a diurnally varying CBL. The set of reactive species is the O3-NO-NO2 triad. The results for both conserved and reactive species are compared with large-eddy simulations (LES) for the same free-convection case using the same boundary and initial conditions. For the conserved species, we compare three cases with different combinations of surface fluxes, and CBL and free-troposphere concentrations. We find good agreement of SOMCRUS with LES for the mean concentrations and fluxes of both conserved and reactive species except near the CBL top, where SOMCRUS predicts a somewhat shallower depth, and has sharp transitions in both the mean and turbulence variables, in contrast to more smeared-out variations in the LES due to horizontal averaging. Furthermore, SOMCRUS generally underestimates the variances and species-species covariances. SOMCRUS predicts temperature-species covariances similar to LES near the surface, but much smaller magnitude peak values near the CBL top, and a change in sign of the covariances very near the CBL top, while the LES predicts a change in sign of the covariances in the lower half of the CBL. SOMCRUS is also able to estimate the intensity of segregation (the ratio of the species-species covariance to the product of their means), which can alter the rates of second-order chemical reactions; however, for

  6. Modeling and Simulation of Optimal Resource Management during the Diurnal Cycle in Emiliania huxleyi by Genome-Scale Reconstruction and an Extended Flux Balance Analysis Approach

    PubMed Central

    Knies, David; Wittmüß, Philipp; Appel, Sebastian; Sawodny, Oliver; Ederer, Michael; Feuer, Ronny

    2015-01-01

    The coccolithophorid unicellular alga Emiliania huxleyi is known to form large blooms, which have a strong effect on the marine carbon cycle. As a photosynthetic organism, it is subjected to a circadian rhythm due to the changing light conditions throughout the day. For a better understanding of the metabolic processes under these periodically-changing environmental conditions, a genome-scale model based on a genome reconstruction of the E. huxleyi strain CCMP 1516 was created. It comprises 410 reactions and 363 metabolites. Biomass composition is variable based on the differentiation into functional biomass components and storage metabolites. The model is analyzed with a flux balance analysis approach called diurnal flux balance analysis (diuFBA) that was designed for organisms with a circadian rhythm. It allows storage metabolites to accumulate or be consumed over the diurnal cycle, while keeping the structure of a classical FBA problem. A feature of this approach is that the production and consumption of storage metabolites is not defined externally via the biomass composition, but the result of optimal resource management adapted to the diurnally-changing environmental conditions. The model in combination with this approach is able to simulate the variable biomass composition during the diurnal cycle in proximity to literature data. PMID:26516924

  7. Diurnal cycle of methane flux from a lake, with high emissions during nighttime caused by convection in the water

    NASA Astrophysics Data System (ADS)

    Podgrajsek, E.; Sahlee, E.; Rutgersson, A.

    2012-12-01

    Many studies have stressed the importance of lakes as major contributors of methane to the atmosphere (e.g. Bastviken et al 2011). However there is still a lack of continuous long time flux measurements over lakes as well as poor understanding of the magnitude of methane fluxes through ebullition and vegetation pathways. In this study the Eddy covariance method has been used for measuring methane fluxes from a lake in central Sweden. At several occasions during the long time measuring campaign (autumn 2010-autumn 2012), a diurnal cycle of methane, with high fluxes during night and low during day, has been captured. Some of the high flux events during nighttime were comparable in magnitude to what previously only been measured from vegetation regions in lakes at these latitudes (e.g. Kankaala et al 2004) and from tropical reservoirs (e.g. Bastviken 2009). During these occasions the difference between air and water temperature (ΔT=Ta-Tw) also displayed an diurnal cycle, with ΔT being positive during day and negative during night with the corresponding change in the sensible heat flux i.e. negative during daytime and positive during nighttime. The high nighttime methane fluxes could be explained with this difference in air and water temperature, which will cool the water surface during night, creating convective mixing in the lake, while during daytime the water will be stably stratified. Temperature measurements made at different vertical levels in the lake water confirm this water stratification. The nighttime convective mixing may act to disturb the bottom water, triggering methane ebullition events and bringing methane rich water up to the surface, which can be emitted to the atmosphere. With this study we want to emphasis the necessity of introducing also complex physical processes when estimating air-water exchange fluxes and also measure methane fluxes not only at few occasions during daytime but also during night and for longer measuring periods. References

  8. Diurnal-activity Patterns of the Small Bee-eater (Merops orientalis) in Southern India

    PubMed Central

    Ali, Abdul Hameed Mohamed Samsoor; Asokan, Subramanian

    2015-01-01

    The diurnal time-activity patterns of the Small Bee-eater (Merops orientalis) were studied between 2005 and 2006 in the Nagapattinam District of Southern India. Bee-eaters were observed to spend an average of 52.5% of their day time scanning, 21.3% feeding, 13.3% flying, 8.8% resting and 4.1% engaging in preening activities. The time spent on scanning varied among seasons in 2005 (p<0.05) and among time blocks (p<0.05), but it did not vary among years or habitats (p>0.05). The feeding patterns differed among years, seasons within years, time blocks and habitats (p<0.05). The flying habits varied among years, time blocks and habitats (p<0.05) but did not change between seasons within years (p>0.05). The resting habits differed among years and habitats (p<0.05) but did not differ among seasons within years or time blocks (p>0.05). Preening differed among years and time blocks (p<0.05) but did not vary among seasons within years or habitats (p>0.05). We conclude that several factors, such as food availability, environmental factors and predation threats, may affect the diurnal activity patterns of Bee-eaters between habitats and seasons; a further study could clarify this conclusion. PMID:26868589

  9. Trait positive and negative emotionality differentially associate with diurnal cortisol activity.

    PubMed

    Miller, Karissa G; Wright, Aidan G C; Peterson, Laurel M; Kamarck, Thomas W; Anderson, Barbara A; Kirschbaum, Clemens; Marsland, Anna L; Muldoon, Matthew F; Manuck, Stephen B

    2016-06-01

    Inter-individual variability in metrics of hypothalamic-pituitary-adrenocortical (HPA) activity, such as the slope of the diurnal decline in cortisol, cortisol awakening response (CAR), and total cortisol output, have been found to associate inversely with trait ratings of extraversion and positive affect (E/PA) and positively with neuroticism and negative affect (N/NA) in some, but not all, investigations. These inconsistencies may partly reflect varied intensity of cortisol sampling among studies and reliance on self-rated traits, which are subject to reporting biases and limitations of introspection. Here, we further examined dispositional correlates of HPA activity in 490 healthy, employed midlife volunteers (M age=43 years; 54% Female; 86% white). Trait ratings were requested from participants and 2 participant-elected informants using the Positive and Negative Affect Schedule (PANAS) and Extraversion and Neuroticism dimensions of NEO personality inventories. CAR was assessed as percent increase in cortisol levels from awakening to 30min after awakening; and the diurnal slope and total output of cortisol [Area Under the Curve (AUC)] were determined from cortisol measurements taken at awakening, +4 and +9h later, and bedtime, across 3 workdays. Structural equation modeling was used to estimate multi-informant E/PA and N/NA factors. We used 3days of measurement as indicators to model each of the three latent cortisol factors (slope, CAR, and AUC). With the two latent emotionality and three latent cortisol indices included there was good fit to the data (χ(2)(200)=278.38, p=0.0002; RMSEA=0.028, 90% CI=0.02-0.04; CFI/TLI=0.97/0.96; SRMR=0.04). After controlling for covariates (age, sex, race), results showed higher latent E/PA associated with a steeper diurnal slope (Standardized β=-0.19, p=0.02) and smaller CAR (Standardized β=-0.26, p=0.004), whereas N/NA did not associate with any cortisol metric (Standardized β's=-0.12 to 0.13, p's=0.10 to 0.53). These

  10. Radar-observed diurnal cycle and propagation of convection over the Pearl River Delta during Mei-Yu season

    NASA Astrophysics Data System (ADS)

    Chen, Xingchao; Zhao, Kun; Xue, Ming; Zhou, Bowen; Huang, Xuanxuan; Xu, Weixin

    2015-12-01

    Using operational Doppler radar and regional reanalysis data from 2007-2009, the climatology and physical mechanisms of the diurnal cycle and propagation of convection over the Pearl River Delta (PRD) region of China during the Mei-Yu seasons are investigated. Analyses reveal two hot spots for convection: one along the south coastline of PRD and the other on the windward slope of mountains in the northeastern part of PRD. Overall, convection occurs most frequently during the afternoon over PRD due to solar heating. On the windward slope of the mountains, convection occurrence frequency exhibits two daily peaks, with the primary peak in the afternoon and the secondary peak from midnight to early morning. The nighttime peak is shown to be closely related to the nocturnal acceleration and enhanced lifting on the windward slope of southwesterly boundary layer flow, in the form of boundary layer low-level jet. Along the coastline, nighttime convection is induced by the convergence between the prevailing onshore wind and the thermally induced land breeze in the early morning. Convection on the windward slope of the mountainous area is more or less stationary. Convection initiated near the coastline along the land breeze front tends to propagate inland from early morning to early afternoon when land breeze cedes to sea breeze and the prevailing onshore flow.

  11. Evolutionary Maps: A new model for the analysis of conceptual development, with application to the diurnal cycle

    NASA Astrophysics Data System (ADS)

    Navarro, Manuel

    2014-05-01

    This paper presents a model of how children generate concrete concepts from perception through processes of differentiation and integration. The model informs the design of a novel methodology (evolutionary maps or emaps), whose implementation on certain domains unfolds the web of itineraries that children may follow in the construction of concrete conceptual knowledge and pinpoints, for each conception, the architecture of the conceptual change that leads to the scientific concept. Remarkably, the generative character of its syntax yields conceptions that, if unknown, amount to predictions that can be tested experimentally. Its application to the diurnal cycle (including the sun's trajectory in the sky) indicates that the model is correct and the methodology works (in some domains). Specifically, said emap predicts a number of exotic trajectories of the sun in the sky that, in the experimental work, were drawn spontaneously both on paper and a dome. Additionally, the application of the emaps theoretical framework in clinical interviews has provided new insight into other cognitive processes. The field of validity of the methodology and its possible applications to science education are discussed.

  12. Changes in seasonal and diurnal cycles of ozone and temperature in the eastern U.S.

    NASA Astrophysics Data System (ADS)

    Bloomer, Bryan J.; Vinnikov, Konstantin Y.; Dickerson, Russell R.

    2010-07-01

    The pollutant tropospheric ozone causes human health problems, and environmental degradation and acts as a potent greenhouse gas. Using long-term hourly observations at five US air quality monitoring surface stations we studied the seasonal and diel cycles of ozone concentrations and surface air temperature to examine the temporal evolution over the past two decades. Such an approach allows visualizing the impact of natural and anthropogenic processes on ozone; nocturnal inversion development, photochemistry, and stratospheric intrusion. Analysis of the result provides an option for determining the duration for a regulatory ozone season. The application of the method provides independent confirmation of observed changes and trends in the ozone and temperature data records as reported elsewhere. The results provide further evidence supporting the assertion that ozone reductions can be attributed to emission reductions as opposed to weather variation. Despite a (˜0.5 °C decade -1) daytime warming trend, ozone decreased by up to 6 ppb decade -1 during times of maximum temperature in the most polluted locations. Ozone also decreased across the emission reduction threshold of 2002 by 6-10 ppb indicating that emission reductions have been effective where and when it is most needed. Longer time series, and coupling with other data sources, may allow for the direct investigation of climate change influence on regional ozone air pollution formation and destruction over annual and daily time scales.

  13. Impacts of the triggering function of cumulus parameterization on warm-season diurnal rainfall cycles at the Atmospheric Radiation Measurement Southern Great Plains site

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Chi; Pan, Hua-Lu; Hsu, Huang-Hsiung

    2015-10-01

    In this study, we investigated the impacts of the triggering function of the deep convection scheme on diurnal rainfall variation in the middle latitudes by using the single-column version of the Community Atmospheric Model (SCAM). Using the climate statistics of a long-term ensemble analysis of SCAM simulations, we quantified and validated the diurnal rainfall climatological regimes at the Atmospheric Radiation Measurement Southern Great Plains (SGP) site. The results showed that the averaged diurnal rainfall cycle simulated using the default Zhang-Mcfarlane (ZM) scheme of the SCAM peaks near noon, which is far earlier than the observed nighttime peak phase. This bias was due to the ZM scheme, which produced spurious daytime rainfall, even during days in which only light rainfall was observed. By contrast, using a weather-focused scheme, the Simplified Arakawa-Schubert (SAS) scheme, we successfully simulated the nocturnal peak of the diurnal cycle. Experiments conducted on the ZM and SAS schemes featuring different triggering functions revealed that the relaxation of launching parcels above the planetary boundary layer (PBL) and the inclusion of convective inhibition (CIN) were crucial designs for the model to capture the nocturnal rainfall events of the SGP. The inclusion of CIN reduces spurious weak convective events, and the allowance of launching parcels being above the PBL better captures convective cloud base. The results of this study highlight the modulatory effect of low-level inhomogeneity on the diurnal variation of convection over midlatitudes and the importance of the triggering function of the deep convection scheme in capturing those variations.

  14. Discernible signals of aerosol effects on the diurnal, weekly and decadal variations in thunderstorm activities

    NASA Astrophysics Data System (ADS)

    Li, Z.

    2015-12-01

    Aerosol can affect atmospheric convection, cloud and precipitation in a variety of means by altering energy balance at the surface and in the atmospheric column, and by altering cloud micro- and macro-physical properties. The effects are often contingent upon meteorological variables and aerosol properties. By reducing surface energy budget, aerosol tends to suppress convection, but aerosol-induced heating in the lower atmosphere can destabilize the upper atmosphere and strengthen convection. Aerosol-induced altering cloud microphysics may also suppress or invigorate cloud development pending on various factors. In this talk, I will illustrate how aerosols likely contribute to the thunderstorm variability on three distinct time scales from diurnal, weekly to decadal and how different types of aerosols and varying meteorological conditions may affect with the observed trends. I will first demonstrate the opposite effects of conservative scattering and hygroscopic aerosols versus absorbing and hydrophobic aerosol on the long-term trends of thunderstorms. I will then illustrate that aerosol can have a discernible effect on the weekly cycle of thunderstorms and there is the dependence of the phase of the weekly cycle on aerosol types. Last, I will show how aerosol delays the occurrence of thunderstorms. Of course, the plausible connections are subject to various uncertainties that should be tackled with more rigorous modeling and extensive observation studies.

  15. Analysis of Diurnal, Planetary and Mean Wind Activity using TIMED, MF and Meteor Radar Winds

    NASA Technical Reports Server (NTRS)

    Lieberman, Ruth S.; Riggin, Dennis R.

    2003-01-01

    The goals of this research are: 1) To validate TIMED Doppler Interferometer (TIDI) winds using ground-based MF and meteor winds; and 2) To examine short-term (i. e., day-to-day and week-to-week) variability of the diurnal tide. This objective was to have originally been met using comparisons of short-term diurnal tidal determinations from ground-based (GB) winds with planetary-scale diurnal nonmigrating tidal definitions from TIDI winds.

  16. Properties of stellar activity cycles

    NASA Astrophysics Data System (ADS)

    Korhonen, Heidi

    2015-08-01

    The current photometric datasets, that span decades, allow for studying long-term magentic cycles on active stars. Complementary Ca H&K observations give information also on the cycles of normal solar-like stars, which have significantly smaller, and less easily detectable, spots. In recent years, high precision space-based observations, for example from the Kepler satellite, have allowed also to study the sunspot-like spot sizes in other stars. In this talk I will review what is known about the properties of the cyclic stellar activity in other stars than our Sun, and also discuss the future prospects in this field.

  17. Seasonal variations of diurnal and semidiurnal tidal-period perturbations in mesopause region temperature and zonal and meridional winds above Fort Collins, Colorado (40 degrees North, 105 degrees West) based on sodium-Lidar observation over full diurnal cycles

    NASA Astrophysics Data System (ADS)

    Yuan, Tao

    With continued efforts by all the members (past and present) in the Na-Lidar group at Colorado State University, the lidar system was capable of simultaneous measurement of mesopause region temperature and horizontal wind at night. Since May 2002, the CSU fluorescence lidar system has been able to perform these observations on 24-hour continuous basis for a long-period, weather permitting. The key factor, which makes lidar observation under sunlit conditions possible, is a pair of robust (reliable and stable) Faraday filters that reduces the sky background. To attain such a Faraday Filter, in this thesis we developed and implemented dual temperature control (to +/-0.1K) of sodium cell inside the filters, and of the cell's tip-off region. The dual control allows independent setting of cell temperature and the Na vapor pressure, thus stabilizing Na vapor density in the cell and the transmission function of the Faraday filter. This 24-hour continuous observation capability provided us with the first yearlong data set with campaigns of full diurnal cycle coverage leading to the first study of diurnal and semidiurnal tides of mesopause region temperature, zonal and meridional winds based on ground based observation. The yearlong data set include a total of 1,491 hours with 659 hours under sunlit conditions, within which there are 29 sets of 24-hour continuous observation. We binned these 29 data sets into bimonthly time series and performed harmonic analysis to deduce diurnal mean, diurnal and semidiurnal tidal-period oscillations of the mesopause region temperature, zonal and meridional winds over Fort Collins, CO. The resulting bimonthly tidal amplitudes and phases are compared to the predictions of Global Scale Wave Models (GSWM00 and GSWM02) and Thermosphere, Ionosphere, Mesosphere and Electrodynamics - General Circulation Model (TIME-GCM02). Other than diurnal temperatures in Nov--Dec, we found excellent agreement between observation and GSWM00 model for diurnal

  18. Basal mTORC2 activity and expression of its components display diurnal variation in mouse perivascular adipose tissue.

    PubMed

    Drägert, Katja; Bhattacharya, Indranil; Hall, Michael N; Humar, Rok; Battegay, Edouard; Haas, Elvira

    2016-04-22

    In adipose tissue mTOR complex 2 (mTORC2) contributes to the regulation of glucose/lipid metabolism and inflammatory molecule expression. Both processes display diurnal variations during the course of the day. RICTOR and mSIN1 are unique and essential components of mTORC2, which is activated by growth factors including insulin. To assess whether mTORC2 components display diurnal variations, we analyzed steady state mRNA expression levels of Rictor, mSin1, and mTor in various adipose tissues during a 24 h period. Diurnally regulated expression of Rictor was detected in brown adipose tissues displaying highest mRNA expression levels at the beginning of the 12 h light period (zeitgeber time 2, ZT2). Gene expression patterns of mSin1 and mTor displayed a similar diurnal regulation as Rictor in PVAT while smaller changes were detected for these genes in aorta during the course of the day. Basal mTORC2 activity was measured by phosphorylation of protein kinase C (PKC) α at serine 657 was higher at ZT14 as compared with ZT2 in PVAT. In line, gene expression of inflammatory molecules nitric oxide synthase 2 and tumor necrosis factor α was lower at ZT 14 compared to ZT2. Our findings provide evidence for a diurnal regulation of expression of mTORC2 components and activity. Hence, mTORC2 is possibly an integral part of diurnally regulated signaling pathways in PVAT and possibly in other adipose tissues. PMID:27016480

  19. Activity cycles of M dwarfs

    NASA Astrophysics Data System (ADS)

    Savanov, I. S.

    2012-09-01

    We have determined activity cycles for coolest M dwarfs using photometry from the ASAS survey. The time scales of brightness variations were determined for the program stars using calculated amplitude power spectra and wavelet spectra. Most of ther program stars display periodicities in their light-curve variations, with periods from hundreds of days to years. Analysis of diagrams plotting P cyc/ P rot versus 1/ P rot in logarithmic coordinates shows that the data for all our program objects fit the general relation quite well. No differences in the activity cycles are found for our sample stars, which have different masses and thus internal structures, some having convective envelopes and others being totally convective. Our analysis indicates that the slope i of this relation is close to unity, regardless of whether it is determined from all data, from data for the shortest cycles, or from data for the longest cycles. This value of i differs from values in the literature for stars of other spectral types. Our analysis of the P cyc- P rot relation indicates that the activity cycles for the studied sample of M dwarfs do not depend on the rotation periods of these objects. The data for the studied objects do not agree with any of the relations for relatively young (active) stars or older (less active) stars. The studied M dwarfs probably form another branch of low-mass stars that display more random, irregular magnetic activity on their surfaces, which is generated and supported by the distributed dynamo mechanism or a small-scale dynamo mechanism.

  20. Seasonal and diurnal cycling of aerosol particles in and above the canopy in the Amazon rain forest

    NASA Astrophysics Data System (ADS)

    Ditas, Florian; Pöhlker, Christopher; Barbosa, Henrique; Brito, Joel; Chi, Xuguang; Krüger, Mira L.; Moran, Daniel; Saturno, Jorge; Su, Hang; Ocimar Manzi, Antonio; Artaxo, Paulo; Pöschl, Ulrich; Andreae, Meinrat O.

    2015-04-01

    The Amazonian rain forest is one of the few continental regions, providing the opportunity to study pristine aerosols approximating a pre-industrial atmosphere. During the wet season, the ambient aerosol is usually unaffected by anthropogenic emission and dominated by a biosphere-atmosphere exchange. In contrast, during the dry season, anthropogenic pollution events (e.g., biomass burning) of regional and/or global character are observed. We will present measurements carried out at a remote research facility in the Amazonian rain forest (ATTO site, S 2° 08' 45'' W 59° 00' 20") approximately 150 km northeast of Manaus. The ATTO site is equipped with a variety of instruments to characterize microphysical and optical particle properties (i.e., particle number size distribution, total particle number concentration, BC mass, scattering coefficients, and chemical composition), which can be operated at two different inlet lines to investigate particles below (5 m) and above canopy (60 m). Since June 2014 a continuous data set of simultaneous particle number size distribution measurements below and above canopy is being collected covering nucleation to coarse mode sizes. The observed particle number size distributions show a pronounced diurnal cycle throughout all size ranges. The number concentration of Aitken and accumulation mode particles exhibits distinct minima before sunrise and a 'growth-like' behavior during daytime, while coarse mode particles show a rather broad minimum and gradual increase during daytime with maximum concentration during nighttime. As already reported by earlier studies, textbook-like new particle formation and growth is not observed in the Amazonian rain forest. Nevertheless, short particle bursts in the nucleation mode size range are regularly observed and show highest abundance in the first half of the night as well as a minimum during daytime. Simultaneous measurements below and above canopy show generally similar results indicating well

  1. Diurnal activity of Rocky Mountain elk (Cervus elaphus) and beef cattle (Bos taurus) grazing a northeastern Oregon summer range

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rocky Mountain elk (Cervus elaphus) and beef cattle (Bos taurus) exist in a complex social environment that is marked by diurnal activities such as periods of foraging, ruminating, resting, and sheltering. Elk unlike cattle, must be continually alert to potential predators. We hypothesize that elk...

  2. SEASONAL AND DIURNAL ACTIVITY PATTERNS IN ANT (HYMENOPTERA: FORMICIDAE) COMMUNITIES IN A VEGETATION TRANSITION REGION OF SOUTHEASTERN NEW MEXICO

    EPA Science Inventory

    The densities of active ant colonies were estimated in three habitats: creosotebush shrubland, grassland, and shinnery-oak mesquite dunes. Diurnal foraging patterns were studied at bait boards. Species richness of ant communities in this transitional region (8-12 species) was co...

  3. Diurnal variations of saltation activity at Tazhong: the hinterland of Taklimakan Desert

    NASA Astrophysics Data System (ADS)

    Yang, Xinghua; He, Qing; Mamtimin, Ali; Huo, Wen; Liu, Xinchun

    2013-02-01

    The Taklimakan Desert of China is a region of frequent sandstorms and, thus, is a major sand and dust source area. Tazhong, a small mining village, is located near the center of the Taklimakan Desert at a distance of 220 km from the desert margins. Near Tazhong, we conducted a 2-year field investigation designed to monitor the diurnal variation of saltation activity using fast-responding piezoelectric saltation sensors (Sensits). Results suggest that saltation activity tends to occur more frequently during daytime in all seasons, relatively high levels of saltation activity are maintained from around 11:30 to around 16:30 local standard time (LST), because of stronger wind speed, higher soil temperature and lower relative humidity. During the spring and summer seasons, the saltation activity can occur at any time of the day, while there are some periods with zero saltation seconds at night and in the early morning during autumn and winter seasons. The results confirm that sandstorms tend to occur more frequently during daylight hours, so it may be helpful to forecast and guard against the occurrence of blowing sand or sandstorms in the Taklimakan Desert.

  4. On the Diurnal Cycle of Deep Convection, High-Level Cloud, and Upper Troposphere Water Vapor in the Multiscale Modeling Framework

    SciTech Connect

    Zhang, Yunyan; Klein, Stephen A.; Liu, Chuntao; Tian, Baijun; Marchand, Roger T.; Haynes, J. M.; McCoy, Renata; Zhang, Yuying; Ackerman, Thomas P.

    2008-08-22

    The Multiscale Modeling Framework (MMF), also called ‘‘superparameterization’’, embeds a cloud-resolving model (CRM) at each grid column of a general circulation model to replace traditional parameterizations of moist convection and large-scale condensation. This study evaluates the diurnal cycle of deep convection, high-level clouds, and upper troposphere water vapor by applying an infrared (IR) brightness temperature (Tb) and a precipitation radar (PR) simulator to the CRM column data. Simulator results are then compared with IR radiances from geostationary satellites and PR reflectivities from the Tropical Rainfall Measuring Mission (TRMM). While the actual surface precipitation rate in the MMF has a reasonable diurnal phase and amplitude when compared with TRMM observations, the IR simulator results indicate an inconsistency in the diurnal anomalies of high-level clouds between the model and the geostationary satellite data. Primarily because of its excessive high-level clouds, the MMF overestimates the simulated precipitation index (PI) and fails to reproduce the observed diurnal cycle phase relationships among PI, high-level clouds, and upper troposphere relative humidity. The PR simulator results show that over the tropical oceans, the occurrence fraction of reflectivity in excess of 20 dBZ is almost 1 order of magnitude larger than the TRMM data especially at altitudes above 6 km. Both results suggest that the MMF oceanic convection is overactive and possible reasons for this bias are discussed. However, the joint distribution of simulated IR Tb and PR reflectivity indicates that the most intense deep convection is found more often over tropical land than ocean, in agreement with previous observational studies.

  5. Fos expression in the sleep-active cell group of the ventrolateral preoptic area in the diurnal murid rodent, Arvicanthis niloticus.

    PubMed

    Novak, C M; Smale, L; Nunez, A A

    1999-02-13

    The ventrolateral preoptic area (VLPO) of the nocturnal laboratory rat receives direct input from the retina and is active during sleep; however, nothing is known about VLPO function in day-active (diurnal) species. In the first study, we used 24-h videotaping of Arvicanthis niloticus, a diurnal murid rodent, to estimate the distribution of sleep and wakefulness across a 12:12 light-dark cycle. Based on behavioral data, A. niloticus were perfused at a time when the animals are inactive (zeitgeber time (ZT) 20) or at a time when they are awake and active (ZT 23). The brains were processed for immunocytochemistry for Fos, an immediate early gene product used as an index of neural activity. Animals had more Fos-immunoreactive (Fos+) cells in the VLPO at ZT 20 than at ZT 23. The pattern of change in Fos expression seen in this area suggest that the VLPO serves the same function in A. niloticus as in rats. Eye injections of cholera toxin (beta subunit) were used to identify the retinal inputs to the VLPO of A. niloticus. In these animals, the VLPO had only very sparse retinal inputs compared to the rat. Together, these results raise the possibility that inputs from the suprachiasmatic nucleus (SCN) or the retina affect neuronal activity in the VLPO differently in rats and A. niloticus, thereby, contributing to differences in their sleep/wake patterns. PMID:10082823

  6. Stellar activity cycles and asteroseismology

    NASA Astrophysics Data System (ADS)

    Salabert, D.

    2011-12-01

    The success of helioseismology is due to its capability to accurately measure the p-mode parameters of the solar eigenmode spectrum, which allow us to infer unique information about the internal structure and dynamics of the Sun from its surface all the way down to the core. It has contributed greatly to a clearer understanding of the Sun and provided insights into the complex solar magnetism, by means for instance of the variability of the characteristics of the p-mode spectrum. Indeed, variations in the mean strength of the solar magnetic field lead to significant shifts in the frequencies of even the lowest-degree p modes with high levels of correlation with solar surface activity proxies. These frequency shifts are explained to arise from structural changes in the outer layers of the Sun during the 11-year activity cycle, which is understood to be driven by a dynamo process. However, clear differences between p-mode frequencies and solar surface activity during the unusually extended minimum of cycle 23 were observed. The origin of the p-mode variability is thus far from being properly understood and a better comprehension of its relationship with solar and stellar activity cycles will help us in our understanding of the dynamo processes. Spectroscopic measurements of Ca H and K emission lines revealed magnetic activity variations in a large sample of solar-type stars with timescales ranging from 2.5 and 25 years. This broad range of cycle periods is thought to reflect differences in the rotational properties and the depths of the surface convection zones with various masses and ages. However, spectroscopic measurements are only good proxies of surface magnetic fields. The recent discovery of variations with magnetic activity in the p-mode oscillation frequencies of the solar-like star HD 49933 observed by CoRoT, with a frequency dependence comparable in shape to the one observed in the Sun, opens a new era in the study of the physical phenomena involved in the

  7. Diurnal and nocturnal activity budgets of zoo elephants in an outdoor facility.

    PubMed

    Horback, Kristina M; Miller, Lance J; Andrews, Jeff R M; Kuczaj, Stan A

    2014-01-01

    The present study examined the activity budgets of 15 African elephants (1 bull, 6 cows, 2 male juveniles, 2 female juveniles, and 4 male calves) living at the San Diego Zoo Safari Park during the summers of 2010 and 2011. Onsite behavioral data (n = 600 hr) were collected for approximately 12 weeks from 0400 to 0830 and 1100 to 2400 during the 2010 and 2011 summer season. Foraging was the most common behavior state during the day followed by resting, and walking. During the evening hours, the elephants spent majority of their time foraging, resting, and sleeping. The average rate of self-maintenance behavior events (dust, wallow, etc.) increased from 0600 to 0700, 1100 to 1500, and from 1700 to 1900. Positive social behavior events (touch other, play, etc.) remained high from 0500 to 2300, with peaks at 0600, 1300, 1500, and 1900. Negative social events occurred at low rates throughout the day and night, with peaks at 0600, 1900, and 2200. The majority of positive behavior events during the daylight and nighttime hours involved the mother-calf pairs. Furthermore, the calves and juveniles initiated approximately 60% of all social events during the daytime and 57% of all social interactions at night. The results of this study demonstrate the differences between diurnal and nocturnal activity budgets of a multi-age and sex elephant herd in a zoological facility, which highlights the importance of managing elephants to meet their 24 hr behavioral needs. PMID:25113850

  8. Foraging Activity Pattern Is Shaped by Water Loss Rates in a Diurnal Desert Rodent.

    PubMed

    Levy, Ofir; Dayan, Tamar; Porter, Warren P; Kronfeld-Schor, Noga

    2016-08-01

    Although animals fine-tune their activity to avoid excess heat, we still lack a mechanistic understanding of such behaviors. As the global climate changes, such understanding is particularly important for projecting shifts in the activity patterns of populations and communities. We studied how foraging decisions vary with biotic and abiotic pressures. By tracking the foraging behavior of diurnal desert spiny mice in their natural habitat and estimating the energy and water costs and benefits of foraging, we asked how risk management and thermoregulatory requirements affect foraging decisions. We found that water requirements had the strongest effect on the observed foraging decisions. In their arid environment, mice often lose water while foraging for seeds and cease foraging even at high energetic returns when water loss is high. Mice also foraged more often when energy expenditure was high and for longer times under high seed densities and low predation risks. Gaining insight into both energy and water balance will be crucial to understanding the forces exerted by changing climatic conditions on animal energetics, behavior, and ecology. PMID:27420785

  9. Tides in the Mesopause Region over Fort Collins, CO (41N, 105W) Based on Lidar Temperature Observations Covering Full Diurnal Cycles

    NASA Astrophysics Data System (ADS)

    She, C. Y.; Chen, S.; Hu, Z.; Williams, B. P.; Krueger, D. A.; Hagan, M. E.

    2001-05-01

    The sodium lidar at Colorado State Univeristy has obtained eighteen sets of 24-hr continuous temperature observations covering a full diurnal cycle distributed throughout the year for 82-102km altitude. These have been analyzed to reveal the seasonal mean amplitude and phase of oscillations with 24, 12, 8,and 6 hour periods. The diurnal and semidiurnal phases typically show clear downward phase propagation, while the ter-dirunal and quad-diurnal components exhibit small amplitudes and disorganized phases as a function of altitude. A comparison of the amplitudes and phases of the diurnal and semidiurnal components with the predictions of the Global-Scale Wave Model showed good general agreement, although better in some seasons than others, suggesting that global-scale migrating tides are the main cause of these oscillations. There is significant variability, however, in the 24 and 12 hr oscillations deduced from the individual 24-hr campaigns within each season. This is most notable in the amplitudes which vary by large factors (amplitudes range from 2K to 20K), even when the corresponding phases are stable to within a few hours, suggesting a modulation of the global migrating tide. This could be caused by time variation in a number of things: the local small-scale wave field, the source stength for global migrating or nonmigrating tide, or changes in the lower atmosphere winds that lead to filtering of any of these waves. It is hoped that future observations that add zonal and meridional wind measurements to the current temperaure measurements with the same durnal and altitude coverage will help clarify the causes of this intra-seasonal variability as well as help resolve the remaining seasonal-average differences between observations and models.

  10. The impacts of heterogeneous land surface fluxes on the diurnal cycle precipitation: A framework for improving the GCM representation of land-atmosphere interactions

    NASA Astrophysics Data System (ADS)

    Wu, Chien-Ming; Lo, Min-Hui; Chen, Wei-Ting; Lu, Chia-Tsung

    2015-05-01

    The present study aims to investigate the modulation of the diurnal cycle precipitation by heterogeneous land surface fluxes. By combining the National Center for Atmospheric Research Community Land Model (CLM) and vector vorticity equation cloud-resolving model (VVM), experiments are designed to understand the responses of diurnal convection to heterogeneous land surface forcings of various spatial scales and intensities. To delineate the land-atmosphere interactions, a two-step off-line approach is adopted. First, the CLM is driven by observational atmospheric forcing with different characteristic length scales and magnitudes. While the surface fluxes from the CLM show no significant difference in the domain-averaged values, their spatial distribution responds significantly to the precipitation heterogeneity. In the second step, the derived CLM surface fluxes are used to drive the VVM. Results show that the timing of precipitation accelerates with increasing magnitude of surface flux perturbation, while the mean and diurnal ranges of precipitation roughly remain the same. The larger perturbation magnitude enhances the boundary layer vertical kinetic energy, which advances the development of the boundary layer. On the other hand, the mean and diurnal ranges of precipitation increase significantly, and the timing of initial precipitation delays with increasing perturbation length scale. The inland breeze induced by the large patches of surface fluxes tends to enhance the mesoscale organization of deep convection, hence the stronger precipitation. The present results highlight the importance of taking heterogeneous land surface fluxes into consideration in future development of general circulation model convection parameterizations associated with land and atmosphere interactions.

  11. The pulse of a montane ecosystem: coupled diurnal cycles in solar flux, snowmelt, evapotranspiration, groundwater, and streamflow at Sagehen Creek (Sierra Nevada, California)

    NASA Astrophysics Data System (ADS)

    Kirchner, James

    2016-04-01

    Forested catchments in the subalpine snow zone provide interesting opportunities to study the interplay between energy and water fluxes under seasonally variable degrees of forcing by transpiration and snowmelt. In such catchments, diurnal cycles in solar flux drive snowmelt and evapotranspiration, which in turn lead to diurnal cycles (with opposing phases) in groundwater levels. These in turn are linked to diurnal cycles in stream stage and discharge, which potentially provide a spatially integrated measure of snowmelt and evapotranspiration rates in the surrounding landscape. Here I analyze ecohydrological controls on diurnal stream and groundwater fluctuations induced by snowmelt and evapotranspiration (ET) at Sagehen Creek, in the Sierra Nevada mountains of California. There is a clear 6-hour lag between radiation forcing and the stream or groundwater response. This is not a travel-time delay, but instead a 90-degree dynamical phase lag arising from the integro-differential relationship between groundwater storage and recharge, ET, and streamflow. The time derivative of groundwater levels is strongly positively correlated with solar flux during snowmelt periods, reflecting snowmelt recharge to the riparian aquifer during daytime. Conversely, this derivative is strongly negatively correlated with solar flux during snow-free summer months, reflecting transpiration withdrawals from the riparian aquifer. As the snow cover disappears, the correlation between the solar flux and the time derivative of groundwater levels abruptly shifts from positive (snowmelt dominance) to negative (ET dominance). During this transition, the groundwater cycles briefly vanish when the opposing forcings (snowmelt and ET) are of equal magnitude, and thus cancel each other out. Stream stage fluctuations integrate these relationships over the altitude range of the catchment. Rates of rise and fall in stream stage are positively correlated with solar flux when the whole catchment is snow

  12. Mouse aldehyde-oxidase-4 controls diurnal rhythms, fat deposition and locomotor activity

    PubMed Central

    Terao, Mineko; Barzago, Maria Monica; Kurosaki, Mami; Fratelli, Maddalena; Bolis, Marco; Borsotti, Andrea; Bigini, Paolo; Micotti, Edoardo; Carli, Mirjana; Invernizzi, Roberto William; Bagnati, Renzo; Passoni, Alice; Pastorelli, Roberta; Brunelli, Laura; Toschi, Ivan; Cesari, Valentina; Sanoh, Seigo; Garattini, Enrico

    2016-01-01

    Aldehyde-oxidase-4 (AOX4) is one of the mouse aldehyde oxidase isoenzymes and its physiological function is unknown. The major source of AOX4 is the Harderian-gland, where the enzyme is characterized by daily rhythmic fluctuations. Deletion of the Aox4 gene causes perturbations in the expression of the circadian-rhythms gene pathway, as indicated by transcriptomic analysis. AOX4 inactivation alters the diurnal oscillations in the expression of master clock-genes. Similar effects are observed in other organs devoid of AOX4, such as white adipose tissue, liver and hypothalamus indicating a systemic action. While perturbations of clock-genes is sex-independent in the Harderian-gland and hypothalamus, sex influences this trait in liver and white-adipose-tissue which are characterized by the presence of AOX isoforms other than AOX4. In knock-out animals, perturbations in clock-gene expression are accompanied by reduced locomotor activity, resistance to diet induced obesity and to hepatic steatosis. All these effects are observed in female and male animals. Resistance to obesity is due to diminished fat accumulation resulting from increased energy dissipation, as white-adipocytes undergo trans-differentiation towards brown-adipocytes. Metabolomics and enzymatic data indicate that 5-hydroxyindolacetic acid and tryptophan are novel endogenous AOX4 substrates, potentially involved in AOX4 systemic actions. PMID:27456060

  13. Mouse aldehyde-oxidase-4 controls diurnal rhythms, fat deposition and locomotor activity.

    PubMed

    Terao, Mineko; Barzago, Maria Monica; Kurosaki, Mami; Fratelli, Maddalena; Bolis, Marco; Borsotti, Andrea; Bigini, Paolo; Micotti, Edoardo; Carli, Mirjana; Invernizzi, Roberto William; Bagnati, Renzo; Passoni, Alice; Pastorelli, Roberta; Brunelli, Laura; Toschi, Ivan; Cesari, Valentina; Sanoh, Seigo; Garattini, Enrico

    2016-01-01

    Aldehyde-oxidase-4 (AOX4) is one of the mouse aldehyde oxidase isoenzymes and its physiological function is unknown. The major source of AOX4 is the Harderian-gland, where the enzyme is characterized by daily rhythmic fluctuations. Deletion of the Aox4 gene causes perturbations in the expression of the circadian-rhythms gene pathway, as indicated by transcriptomic analysis. AOX4 inactivation alters the diurnal oscillations in the expression of master clock-genes. Similar effects are observed in other organs devoid of AOX4, such as white adipose tissue, liver and hypothalamus indicating a systemic action. While perturbations of clock-genes is sex-independent in the Harderian-gland and hypothalamus, sex influences this trait in liver and white-adipose-tissue which are characterized by the presence of AOX isoforms other than AOX4. In knock-out animals, perturbations in clock-gene expression are accompanied by reduced locomotor activity, resistance to diet induced obesity and to hepatic steatosis. All these effects are observed in female and male animals. Resistance to obesity is due to diminished fat accumulation resulting from increased energy dissipation, as white-adipocytes undergo trans-differentiation towards brown-adipocytes. Metabolomics and enzymatic data indicate that 5-hydroxyindolacetic acid and tryptophan are novel endogenous AOX4 substrates, potentially involved in AOX4 systemic actions. PMID:27456060

  14. The influence of sleep onset on the diurnal variation in cardiac activity and cardiac control.

    PubMed

    Carrington, Melinda; Walsh, Michelle; Stambas, Thalia; Kleiman, Jan; Trinder, John

    2003-09-01

    Heart rate (HR), blood pressure (BP) and autonomic nervous system (ANS) activity vary diurnally, with a reduction in HR and BP, and a shift to vagal dominance during the dark phase. However, the cause of these changes, particularly the relative influence of sleep and circadian mechanisms, remains uncertain. The present study assessed the effect of sleep onset on HR, BP, high frequency (HF) component of heart rate variability (HRV), low frequency/high frequency (LF/HF) ratio and pre-ejection period (PEP). Sleep onset was dissociated from circadian influences by having subjects go to sleep at two different circadian phases, their normal time of sleep onset (normal sleep onset, NSO), and after a delay of 3 h (delayed sleep onset, DSO). The assumption was that changes caused by sleep onset would occur in association with sleep onset, irrespective of its timing, while circadian effects would have a consistent circadian phase and be independent of when sleep onset occurred. Thirteen and 17 subjects were run in the NSO and DSO conditions, respectively. Following a 1-h adaptation period, data collection began 2 h before subjects' normal time of sleep onset and continued until morning awakening. The lights were turned out after 2 h in the NSO condition and 5 h in the DSO condition. Subjects were required to maintain a supine position throughout the experimental sessions. The night-time decrease in HR was found to be due to both sleep onset and a circadian influence, with the circadian component being more prominent. In contrast, the fall in BP was largely due to a sleep onset effect. Increased vagal activity, as reflected in the HF component and a shift to vagal dominance in the LF/HF ratio, appeared to be primarily a function of the sleep system, while sympathetic activity, as assessed by PEP, reflected a circadian influence. PMID:12941060

  15. Modeling cloud microphysics using a two-moments hybrid bulk/bin scheme for use in Titan’s climate models: Application to the annual and diurnal cycles

    NASA Astrophysics Data System (ADS)

    Burgalat, J.; Rannou, P.; Cours, T.; Rivière, E. D.

    2014-03-01

    Microphysical models describe the way aerosols and clouds behave in the atmosphere. Two approaches are generally used to model these processes. While the first approach discretizes processes and aerosols size distributions on a radius grid (bin scheme), the second uses bulk parameters of the size distribution law (its mathematical moments) to represent the evolution of the particle population (moment scheme). However, with the latter approach, one needs to have an a priori knowledge of the size distributions. Moments scheme for Cloud microphysics modeling have been used and enhanced since decades for climate studies of the Earth. Most of the tools are based on Log-Normal law which are suitable for Earth, Mars or Venus. On Titan, due to the fractal structure of the aerosols, the size distributions do not follow a log-normal law. Then using a moment scheme in that case implies to define the description of the size distribution and to review the equations that are widely published in the literature. Our objective is to enable the use of a fully described microphysical model using a moment scheme within a Titan’s Global Climate Model. As a first step in this direction, we present here a moment scheme dedicated to clouds microphysics adapted for Titan’s atmosphere conditions. We perform comparisons between the two kinds of schemes (bin and moments) using an annual and a diurnal cycle, to check the validity of our moment description. The various forcing produce a time-variable cloud layer in relation with the temperature cycle. We compare the column opacities and the temperature for the two schemes, for each cycles. We also compare more detailed quantities as the opacity distribution of the cloud events at different periods of these cycles. Results show that differences between the two approaches have a small impact on the temperature (less than 1 K) and range between 1% and 10% for haze and clouds opacities. Both models behave in similar way when forced by an annual

  16. Identification of Diurnal, Seasonal and Inter-Annual Variability Across SE Asian Field Observations of key Water Cycle Variables: Rainfall, net Radiation, Total Evaporation and River Discharge

    NASA Astrophysics Data System (ADS)

    Solera García, M. A.; Tych, W.; Chappell, N.

    2007-12-01

    The identification of periodic patterns in water cycle variables is critical to the understanding of land-atmosphere interactions, climate change and the evaluation of General Circulation Model (GCM) output. SE Asia in particular plays a very important role on the global climate because it is a large source of energy and water fluxes into the upper atmosphere. Cycle identification is carried out following the Data Based Mechanistic (DBM) philosophy, which focuses on the use of parsimonious, rigorous models which are characterised by lack of a priori assumptions, built in uncertainty analysis and final model acceptance dependent on the physical interpretation of the results. The DBM tool used here is the Unobserved Component - Dynamic Harmonic Regression (UC-DHR) model, which is a statistical method that allows the identification of variability in time series by introducing Time Variable Parameter (TVP) estimation of harmonic components. UC-DHR is not scale dependent and was thus applied to both hourly (to investigate diurnal variation) and fortnightly datasets (for intra- and inter-annual variability). The data used in the analysis has been gathered from existing catchment datasets for three regions of tropical SE Asia, namely Northern Thailand, Central Peninsular Malaysia and Northeast Borneo. These regions were chosen because they represent the hydro-climatic gradient (seasonal to equatorial) present within the tropics and because SE Asia has the most extensive set of catchment/plot studies within the humid tropics. Results show modeling tools were able to quantify the main patterns present in the observations throughout different time scales (diurnal, intra-annual and inter-annual) and the strength of the correlation pattern between the four hydro-climatic variables. The subsequent discussion focuses on the physical processes behind those patterns (e.g. diurnal variability caused by local convection due to solar heating; impact of El Niño Southern Oscillation

  17. Day-night differences in neural activation in histaminergic and serotonergic areas with putative projections to the cerebrospinal fluid in a diurnal brain.

    PubMed

    Castillo-Ruiz, A; Gall, A J; Smale, L; Nunez, A A

    2013-10-10

    In nocturnal rodents, brain areas that promote wakefulness have a circadian pattern of neural activation that mirrors the sleep/wake cycle, with more neural activation during the active phase than during the rest phase. To investigate whether differences in temporal patterns of neural activity in wake-promoting regions contribute to differences in daily patterns of wakefulness between nocturnal and diurnal species, we assessed Fos expression patterns in the tuberomammillary (TMM), supramammillary (SUM), and raphe nuclei of male grass rats maintained in a 12:12 h light-dark cycle. Day-night profiles of Fos expression were observed in the ventral and dorsal TMM, in the SUM, and in specific subpopulations of the raphe, including serotonergic cells, with higher Fos expression during the day than during the night. Next, to explore whether the cerebrospinal fluid is an avenue used by the TMM and raphe in the regulation of target areas, we injected the retrograde tracer cholera toxin subunit beta (CTB) into the ventricular system of male grass rats. While CTB labeling was scarce in the TMM and other hypothalamic areas including the suprachiasmatic nucleus, which contains the main circadian pacemaker, a dense cluster of CTB-positive neurons was evident in the caudal dorsal raphe, and the majority of these neurons appeared to be serotonergic. Since these findings are in agreement with reports for nocturnal rodents, our results suggest that the evolution of diurnality did not involve a change in the overall distribution of neuronal connections between systems that support wakefulness and their target areas, but produced a complete temporal reversal in the functioning of those systems. PMID:23867764

  18. Regulation of diurnal variation of cholesterol 7alpha-hydroxylase (CYP7A1) activity in healthy subjects.

    PubMed

    Kovár, J; Lenícek, M; Zimolová, M; Vítek, L; Jirsa, M; Pitha, J

    2010-01-01

    Cholesterol 7alpha-hydroxylase (CYP7A1), the key regulatory enzyme of bile acid synthesis, displays a pronounced diurnal variation. To better understand the regulation of CYP7A1 activity, three day-long examinations were carried out in 12 healthy men. The concentrations of 7alpha-hydroxycholest-4-en-3-one (C4), a surrogate marker of CYP7A1 activity, bile acids (BA), insulin, glucose, nonesterified fatty acids, triglycerides, and cholesterol were measured in serum in 90-min intervals from 7 AM till 10 PM. To lower and to increase BA concentration during the study, the subjects received cholestyramine and chenodeoxycholic acid (CDCA), respectively, in two examinations. No drug was used in the control examination. There was a pronounced diurnal variation of C4 concentration with a peak around 1 PM in most of the subjects. The area under the curve (AUC) of C4 concentration was five times higher and three times lower when subjects were treated with cholestyramine and CDCA, respectively. No relationship was found between AUC of C4 and AUC of BA concentration, but AUC of C4 correlated positively with that of insulin. Moreover, short-term treatment with cholestyramine resulted in about 10 % suppression of glycemia throughout the day. Our results suggest that insulin is involved in the regulation of diurnal variation of CYP7A1 activity in humans. PMID:19537927

  19. Analysis of the Diurnal Cycle of Precipitation and its Relation to Cloud Radiative Forcing using TRMM Products

    NASA Technical Reports Server (NTRS)

    Randall, David A.; Fowler, Laura D.

    2000-01-01

    By incorporating the Tropical Rain Measuring Mission (TRMM) satellite orbital information into the geodesic version of the Colorado State University General Circulation Model (CSU GCM), we are able to fly a satellite in the GCM, and sample the simulated atmosphere in the same way as the TRMM sensors sample the real atmosphere. The TRMM sampling statistics of precipitation and radiative fluxes at annual, intraseasonal, monthly-mean and composited diurnal time scales are evaluated by comparing the satellite-sampled against fully-sampled simulated atmospheres. This information provides a valuable guidance for efficient usage of TRMM data and future satellite mission planning.

  20. The Diurnal Cycle of Particle Sizes, Compositions, and Densities observed in Sacramento, CA during CARES Field Campaign

    NASA Astrophysics Data System (ADS)

    Beránek, J.; Vaden, T.; Imre, D. G.; Zelenyuk, A.

    2010-12-01

    A central objective of the Carbonaceous Aerosol and Radiative Effects Study (CARES) was to characterize unequivocally all aspects related to organics in aerosols. To this end, a range of instruments measured loadings, size distributions, compositions, densities, CCN activities, and optical properties of aerosol sampled in Sacramento, CA over the month of June 2010. We present the results of measurements conducted by our single particle mass spectrometer, SPLAT. SPLAT was used to measure the size, composition, and density of individual particles with diameters between 50 to 2000 nm. SPLAT measured the vacuum aerodynamic diameters (dva) of more than 2 million particles and the compositions of ~350,000 particles, each day. In addition, SPLAT was used in combination with a differential mobility analyzer to measure the density, or effective density of individual particles. These measurements were typically conducted twice per day: in the morning, and mid-afternoon. Preliminary analysis of the data shows that under most conditions, the particles were relatively small (below 200 nm), and the vast majority of them were composed of oxygenated organics mixed with various amounts of sulfates. Analysis of the mass spectra shows that the oxygenated organics in these particles are the oxidized products of biogenic volatile organic precursors. In addition to particles composed of SOA mixed with sulfates, we detected and characterized fresh and processed soot particles, biomass burning aerosol, organic amines, sea salt - fresh and processed - and a small number of dust and other inorganic particles, commonly found in urban environment. SOA mixed with sulfates were the vast majority of particles at all times, while the other particle types exhibited episodic behavior. The data shows a reproducible diurnal pattern in SOA size distributions, number concentrations, and compositions. Early in the morning the particle number concentrations are relatively low, and the particle size

  1. Mars Global Ionosphere-Thermosphere Model: Solar cycle, seasonal, and diurnal variations of the Mars upper atmosphere

    NASA Astrophysics Data System (ADS)

    Bougher, S. W.; Pawlowski, D.; Bell, J. M.; Nelli, S.; McDunn, T.; Murphy, J. R.; Chizek, M.; Ridley, A.

    2015-02-01

    A new Mars Global Ionosphere-Thermosphere Model (M-GITM) is presented that combines the terrestrial GITM framework with Mars fundamental physical parameters, ion-neutral chemistry, and key radiative processes in order to capture the basic observed features of the thermal, compositional, and dynamical structure of the Mars atmosphere from the ground to the exosphere (0-250 km). Lower, middle, and upper atmosphere processes are included, based in part upon formulations used in previous lower and upper atmosphere Mars GCMs. This enables the M-GITM code to be run for various seasonal, solar cycle, and dust conditions. M-GITM validation studies have focused upon simulations for a range of solar and seasonal conditions. Key upper atmosphere measurements are selected for comparison to corresponding M-GITM neutral temperatures and neutral-ion densities. In addition, simulated lower atmosphere temperatures are compared with observations in order to provide a first-order confirmation of a realistic lower atmosphere. M-GITM captures solar cycle and seasonal trends in the upper atmosphere that are consistent with observations, yielding significant periodic changes in the temperature structure, the species density distributions, and the large-scale global wind system. For instance, mid afternoon temperatures near ˜200 km are predicted to vary from ˜210 to 350 K (equinox) and ˜190 to 390 k (aphelion to perihelion) over the solar cycle. These simulations will serve as a benchmark against which to compare episodic variations (e.g., due to solar flares and dust storms) in future M-GITM studies. Additionally, M-GITM will be used to support MAVEN mission activities (2014-2016).

  2. CRTC2 activation in the suprachiasmatic nucleus, but not paraventricular nucleus, varies in a diurnal fashion and increases with nighttime light exposure

    PubMed Central

    Highland, Julie A.; Weiser, Michael J.; Hinds, Laura R.

    2014-01-01

    Entrainment of the intrinsic suprachiasmatic nucleus (SCN) molecular clock to the light-dark cycle depends on photic-driven intracellular signal transduction responses of SCN neurons that converge on cAMP response element-binding protein (CREB)-mediated regulation of gene transcription. Characterization of the CREB coactivator proteins CREB-regulated transcriptional coactivators (CRTCs) has revealed a greater degree of differential activity-dependent modulation of CREB transactivational function than previously appreciated. In confirmation of recent reports, we found an enrichment of crtc2 mRNA and prominent CRTC2 protein expression within the SCN of adult male rats. With use of a hypothalamic organotypic culture preparation for initial CRTC2-reactive antibody characterization, we found that CRTC2 immunoreactivity in hypothalamic neurons shifted from a predominantly cytoplasmic profile under basal culture conditions to a primarily nuclear localization (CRTC2 activation) 30 min after adenylate cyclase stimulation. In adult rat SCN, we found a diurnal variation in CRTC2 activation (peak at zeitgeber time of 4 h and trough at zeitgeber time of 16–20 h) but no variation in the total number of CRTC2-immunoreactive cells. There was no diurnal variation of CRTC2 activation in the hypothalamic paraventricular nucleus, another site of enriched CRTC2 expression. Exposure of rats to light (50 lux) for 30 min during the second half of their dark (nighttime) phase produced CRTC2 activation. We observed in the SCN a parallel change in the expression of a CREB-regulated gene (FOS). In contrast, nighttime light exposure had no effect on CRTC2 activation or FOS expression in the paraventricular nucleus, nor did it affect corticosterone hormone levels. These results suggest that CRTC2 participates in CREB-dependent photic entrainment of SCN function. PMID:25080490

  3. Diurnal variation in the fraction of 3-hydroxy-3-methylglutaryl-coenzyme A reductase in the active form in the mammary gland of the lactating rat.

    PubMed Central

    Smith, R A; Middleton, B; West, D W

    1986-01-01

    'Expressed' and 'total' activities of 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase) were measured in freeze-clamped samples of mammary glands from lactating rats at intervals throughout the 24 h light/dark cycle. 'Expressed' activities were measured in microsomal fractions isolated and assayed in the presence of 100 mM-KF. 'Total' activities were determined in microsomal preparations from the same homogenates but washed free of KF and incubated with exogenously added sheep liver phosphoprotein phosphatase before assay. Both 'expressed' and 'total' activities of HMG-CoA reductase underwent a diurnal cycle, which had a major peak 6 h into the light phase and a nadir 15 h later, i.e. 9 h into the dark period. Both activities showed a secondary peak of activity (around 68% of the maximum activity) at the time of changeover from dark to light, with a trough in the value of the 'expressed' activity that was close to the nadir value. 'Expressed' activity was lower than 'total' at all time points, indicating the presence of enzyme molecules inactivated by covalent phosphorylation. Nevertheless the 'expressed'/'total' activity ratio was comparatively constant and varied only between 43% and 75%. Immunotitration of enzyme activity, with antiserum raised in sheep against purified rat liver HMG-CoA reductase, confirmed the presence of both active and inactive forms of the enzyme and indicated that at the peak and nadir the variation in 'expressed' HMG-CoA reductase activity resulted from changes in the total number of enzyme molecules rather than from covalent modification. The sample obtained after 3 h of the light phase exhibited an anomalously low 'total' HMG-CoA reductase activity, which could be increased when Cl- replaced F- in the homogenization medium. The result suggests that at that time the activity of the enzyme could be regulated by mechanisms other than covalent phosphorylation or degradation. PMID:3814075

  4. An "In Situ" Calibration Correction Procedure (KCICLO) Based on AOD Diurnal Cycle: Application to AERONET-El Arenosillo (Spain) AOD Data Series

    SciTech Connect

    Cachorro, V. E.; Toledano, C.; Berjon, A.; de Frutos, A. M.; Torres, B.; Sorribas, M.; Laulainen, Nels S.

    2008-06-21

    Aerosol optical depth (AOD) very often shows a distinct diurnal cycle pattern, which seems to be an artifact resulting from an incorrect calibration (or an equivalent effect, such as filter degradation). The shape of this fictitious AOD diurnal cycle varies as the inverse of the solar air mass (m) and the magnitude of the effect is greatest at midday. The observation of this effect is not easy at many field stations, and only those stations with good weather conditions permit an easier detection and the possibility of its correction. By taking advantage of this dependence on the air mass, we propose an improved “in situ” correction-calibration procedure to AOD measured data series. The method is named KCICLO because the determination of a constant K and the behavior of AOD as a cycle (ciclo, in Spanish). We estimate it has an accuracy of 0.2–0.5% for the calibration ratio constant K, or 0.002–0.005 in AOD at field stations. Although the KCICLO is an “in situ” calibration method, we recommend it to be used as an AOD correction method for field stations. At high-altitude sites, it may be used independently of the classical Langley method (CLM). However, we also recommend it to be used as a complement to CLM, improving it considerably. The application of this calibration correction method to the nearly 5 year AOD data series at El Arenosillo (Huelva, southwestern Spain) station belonging to Aerosol Robotic Network (AERONET)-PHOTONS shows that 8 (50%) of 16 filters of the four analyzed Sun photometers were outside of the 0.02 uncertainty of AERONET specification. The largest departures reached values of 0.06. The results show the efficiency of the method and a significant improvement over other “in situ” methods, with no other information required beyond the same AOD data.

  5. Diurnal time-activity budgets of redheads (Aythya americana) wintering in seagrass beds and coastal ponds in Louisiana and Texas

    USGS Publications Warehouse

    Michot, T.C.; Woodin, M.C.; Adair, S.E.; Moser, E.B.

    2006-01-01

    Diurnal time-activity budgets were determined for wintering redheads (Aythya americana) from estuarine seagrass beds in Louisiana (Chandeleur Sound) and Texas (Laguna Madre) and from ponds adjacent to the Laguna Madre. Activities differed (p<0.0001) by location, month, and diurnal time period. Resting and feeding were the most frequent activities of redheads at the two estuarine sites, whereas drinking was almost nonexistent. Birds on ponds in Texas engaged most frequently in resting and drinking, but feeding was very infrequent. Redheads from the Louisiana estuarine site rested less than birds in Texas at either the Laguna Madre or freshwater ponds. Redheads in Louisiana fed more than birds in Texas; this was partially because of weather differences (colder temperatures in Louisiana), but the location effect was still significant even when we adjusted the model for weather effects. Redheads in Louisiana showed increased resting and decreased feeding as winter progressed, but redheads in Texas did not exhibit a seasonal pattern in either resting or feeding. In Louisiana, birds maintained a high level of feeding activity during the early morning throughout the winter, whereas afternoon feeding tapered off in mid- to late-winter. Texas birds showed a shift from morning feeding in early winter to afternoon feeding in late winter. Males and females at both Chandeleur Sound and Laguna Madre showed differences in their activities, but because the absolute difference seldom exceeded 2%, biological significance is questionable. Diurnal time-activity budgets of redheads on the wintering grounds are influenced by water salinities and the use of dietary fresh water, as well as by weather conditions, tides, and perhaps vegetation differences between sites. The opportunity to osmoregulate via dietary freshwater, vs. via nasal salt glands, may have a significant effect on behavioral allocations. ?? Springer 2006.

  6. Four years of CO2 and meteorological measurements in Mataró (Catalonia, Spain). An example of the CO2 diurnal cycles in a Mediterranean coastal city.

    NASA Astrophysics Data System (ADS)

    Curcoll Masanes, Roger; Font, Anna; Comerma, Marta; Morguí, Josep-Anton; Àgueda, Alba; Batet, Oscar; Cañas, Lidia; Grossi, Claudia; Nofuentes, Manel; Occhipinti, Paola; Rodó, Xavier

    2014-05-01

    Since November 2009, in collaboration with the science section of the Mataró Museum, IC3 is measuring CO2 concentration in the roof of this museum using a calibrated infrared (IR) analyzer (GMP343 Vaisala Carbocap®). The measurements began within the frame of the CarboSchools project (EU Science in Society programme). Meteorological variables (ambient temperature, relative humidity, precipitation, barometric pressure, wind direction and wind speed) are also measured with a Davis Vantage Pro2 Station. The Mataró Museum is located in the Mediterranean coastal city of Mataró (41.540174° N, 2.445486° E), 25 Km north-east of Barcelona. The in-situ meteorological data (pressure, temperature and humidity) is used to adjust the settings of the GMP343 every minute to calculate CO2 concentration. From late 2009 to 2012 CO2 data was calibrated using integrated discrete flask samples that were collected fortnightly and then measured using an optical analyzer (Licor-7000). From 2013 onwards CO2 GMP343 data has been calibrated by data inter-comparison with a Picarro G2301. Both the Picarro G2301 and the Licor-7000 analyzers were calibrated and referred to the International Scale using a scale strategy with seven NOAA reference cylinders. The dataset shows that CO2 signal in the coastal city of Mataró is regulated by the periodic land-sea breezes and the local emissions. The CO2 variability along the year (diurnal and seasonal CO2 signal) responds to the variability of the influence of the sea-land breezes, the contribution of the land and the sea ecosystems in the CO2 cycle and the variability of anthropogenic emissions Finally the CO2 data from Mataró is compared with the CO2 time series from other stations which have the same equipment but are located in different ecosystems. The other stations presented here are (1) DEC3: Located at the Ebre River Delta in a coastal and agricultural area. This station is also provided with GC and Picarro instrumentation and is part of

  7. Physiological basis for diurnal activity in dispersing juvenile Bufo granulosus in the Caatinga, a Brazilian semi-arid environment.

    PubMed

    Navas, Carlos A; Antoniazzi, Marta M; Carvalho, José E; Suzuki, Hana; Jared, Carlos

    2007-07-01

    Diurnal activity is characteristic of many toad species, including Bufo granulosus from the Brazilian semi-arid biome called the Caatinga. Because of their patterns of activity, juvenile toads are exposed to hot and dehydrating conditions. Our investigation focuses on temperature and water relationships, and is based on the prediction that anuran diurnal activity in a semi-arid environment must be associated with morphological, physiological and behavioral traits enhancing thermal tolerances, capacity for performance at high temperatures and water balance. To test specific hypothesis related with this prediction, we investigated postmetamorphic B. granulosus and collected data on thermal tolerances and preferences, thermal safety margins, thermal dependence of locomotor behavior, thermal and kinetic properties of citrate synthase (CS), and skin morphophysiology. This information was compared with additional data from adult conspecifics and adult toads from sympatric species or from species from more moderate environments. We found that juvenile B. granulosus exhibit the highest critical maximum temperature reported for toads (44.2 degrees C) and are well suited to move at high temperatures. However, and in contrast with juveniles of other Bufo species, they do not show thermal preferences in a gradient and appear to hydroregulate more than thermoregulate. The CS of adult and juvenile toads shows typical patterns of thermal sensibility, but the thermal stability of this enzyme is much higher in juveniles than in adult Bufo of any other species studied. The inguinal skin exhibits a complex folding pattern and seems highly specialized for capillary water uptake. Diurnal activity in juvenile B. granulosus is possible given high thermal tolerances, keen ability to detect and uptake water, and avoidance behaviors. PMID:17234442

  8. Photoregulation of Biological Activity by Photochromic Reagents, IV. A Model for Diurnal Variation of Enzymic Activity*

    PubMed Central

    Bieth, Joseph; Wassermann, Norbert; Vratsanos, Spyros M.; Erlanger, Bernard F.

    1970-01-01

    Levels of acetylcholinesterase activity can be made to vary in response to the presence or absence of sunlight in a system that can be considered as a model for photoperiodic processes found in nature. The enzyme is rendered photosensitive by the presence of a photochromic inhibitor, N-p-phenylazophenylcarbamyl choline, which changes from a trans to a cis isomer under the influence of the light of the sun and reverts back to the trans isomer in the dark. The two isomers differ in their ability acetylcholinesterase, thus rendering the enzyme system responsive to sunlight. The relationship of this system to photoresponsive processes in nature is discussed, and a possible role in photoregulation is suggested for naturally occurring carotenoids. PMID:5269248

  9. Diurnal and Seasonal Cycles of CO2 Fluxes in the low Deciduous Forest in the South of Sonora, Mexico

    NASA Astrophysics Data System (ADS)

    Perez-Ruiz, E.; Garatuza-Payan, J.; Garcia-Calleja, M. T.; Watts, C. J.

    2007-05-01

    The Deciduous Seasonal Forest or Low Deciduous Forest (LDF) is one of the most diverse and most contrasting ecosystems in Mexico. It can be found from the south of the northern state of Sonora to the border of Mexico with Guatemala. This ecosystem is very important to the region since it represents a big area of vegetal cover close to the biggest cities of South Sonora (hence, endangered), and can be considered as a sink of carbon dioxide. In the present study, the CO2 fluxes over the LDF were analyzed in the period from June 2004 to December 2006. The CO2, latent and sensible heat, and momentum fluxes were measured using the Eddy covariance method. The Eddy covariance system consists of a 3-D sonic anemometer (CSAT3, Campbell Scientific), a gas analyzer (LI-7500, LI-COR), and diverse meteorological equipment controlled by a datalogger (CR5000, Campbell Scientific). The measures were made at 10Hz, collecting, storing and averaging the measurements every 30 minutes. The same type of cover is present in, at least, 3 km around the tower. The results show a large range in the diurnal variation of the CO2 fluxes, with values from -1.5 (day) to 0.8 (night) mg CO2 m- 2s-1 (negative values indicate uptake) in the summer, and from -0.5 to 0.15 mg CO2 m-2s- 1 during the winter. This ecosystems presents a clear growing season corresponding to the rain season in the summer, nevertheless, even in the dry season, the LDF can be considered as a sink of carbon dioxide during some hours around the midday.

  10. On the diurnal cycle of urban aerosols, black carbon and the occurrence of new particle formation events in springtime São Paulo, Brazil

    NASA Astrophysics Data System (ADS)

    Backman, J.; Rizzo, L. V.; Hakala, J.; Nieminen, T.; Manninen, H. E.; Morais, F.; Aalto, P. P.; Siivola, E.; Carbone, S.; Hillamo, R.; Artaxo, P.; Virkkula, A.; Petäjä, T.; Kulmala, M.

    2012-12-01

    Large conurbations are a significant source of the anthropogenic pollution and demographic differences between cities that result in a different pollution burden. The metropolitan area of São Paulo (MASP, population 20 million) accounts for one fifth of the Brazilian vehicular fleet. A feature of MASP is the amount of ethanol used by the vehicular fleet, known to exacerbate air quality. The study describes the diurnal behaviour of the submicron aerosol and relies on total particle number concentration, particle number size distribution, light scattering and light absorption measurements. Modelled planetary boundary layer (PBL) depth and air mass movement data were used to aid the interpretation. During morning rush-hour, stagnant air and a shallow PBL height favour the accumulation of aerosol pollution. During clear-sky conditions, there was a wind shift towards the edge of the city indicating a heat island effect with implications on particulate pollution levels at the site. The median total particle number concentration for the submicron aerosol typically varied in the range 1.6 × 104-3.2 × 104 cm-3 frequently exceeding 4 × 104 cm-3 during the day. During weekdays, nucleation-mode particles are responsible for most of the particles by numbers. The highest concentrations of total particle number concentrations and black carbon (BC) were observed on Fridays. Median diurnal values for light absorption and light scattering (at 637 nm wavelength) varied in the range 12-33 Mm-1 and 21-64 Mm-1, respectively. The former one is equal to 1.8-5.0 μg m-3 of BC. The growth of the PBL, from the morning rush-hour until noon, is consistent with the diurnal cycle of BC mass concentrations. Weekday hourly median single-scattering albedo (ω0) varied in the range 0.59-0.76. Overall, this suggests a top of atmosphere (TOA) warming effect. However, considering the low surface reflectance of urban areas, for the given range of ω0, the TOA radiative forcing can be either positive

  11. The influence of enclosure design on diurnal activity and stereotypic behaviour in captive Malayan Sun bears (Helarctos malayanus).

    PubMed

    Tan, H M; Ong, S M; Langat, G; Bahaman, A R; Sharma, R S K; Sumita, S

    2013-04-01

    The effect of enclosure design on diurnal activity and stereotypic behaviour was assessed in 17 adult Malayan Sun bears (Helarctos malayanus), kept either in barren indoor enclosures or relatively enriched outdoor enclosures. Locomotion was the most frequent activity observed in the indoor bears, followed by resting. In contrast, conspecifics housed outdoors spent most of the time resting. Eleven forms of stereotypic behaviours were recorded in the bears, with pacing being the most common. The frequency and repertoire of stereotypies were significantly higher in the indoor bears irrespective of enclosure size. Novel forms of locomotor (forward-reverse pacing) and oral (allo-sucking) stereotypies were recorded. Oral stereotypies were predominant in the bears housed indoors, while patrolling was confined to the outdoor bears. Enclosure complexity significantly influences activity budget and occurrence of stereotypic behaviours, highlighting the importance of appropriate enclosure design and enrichment for the welfare of captive bears. PMID:23141171

  12. A quantitative analysis of the effects of activity and time of day on the diurnal variations of blood pressure.

    PubMed

    Clark, L A; Denby, L; Pregibon, D; Harshfield, G A; Pickering, T G; Blank, S; Laragh, J H

    1987-01-01

    The effects of activity and time of day on blood pressure (BP) were analyzed in 461 patients with untreated hypertension who wore a noninvasive portable BP recorder which took readings every 15 minutes for 24 hours. Patients recorded activity and location in a diary. The data were analyzed separately for two groups of patients: the 190 who stayed at home and the 271 who went to work. The effects of 16 different activities on BP were estimated by relating the BP to the associated activity and to the individual's clinic BP. Blood pressure was higher at work than at home, but the increment of BP for individual activities was similar in the two locations. The overall effect of activities on BP variability was computed using a one-way analysis of covariance model. For the patients who went to work this model accounted for 40% of the observed variation (R2) for systolic and 39% for diastolic BP. A similar model using time of day instead of activity accounted for 33% of variability in both systolic and diastolic BP. Combining activity and time of day was little better than activity alone (41% for both). After allowing for the effects of activity on BP, where sleep is one of the activities, there was no significant diurnal variation of BP. We conclude that there is no important circadian rhythm of BP which is independent of activity. PMID:3597670

  13. Assessing the diurnal variability of pharmaceutical and personal care products in a full-scale activated sludge plant.

    PubMed

    Salgado, R; Marques, R; Noronha, J P; Mexia, J T; Carvalho, G; Oehmen, A; Reis, M A M

    2011-10-01

    An intensive sampling campaign has been carried out in a municipal wastewater treatment plant (WWTP) to assess the dynamics of the influent pharmaceutical active compounds (PhAC) and musks. The mass loadings of these compounds in wastewater influents displayed contrasting diurnal variations depending on the compound. The musks and some groups of PhACs tended to follow a similar diurnal trend as compared to macropollutants, while the majority of PhACs followed either the opposite trend or no repeatable trend. The total musk loading to the WWTP was 0.74 ± 0.25 g d(-1), whereas the total PhAC mass loading was 84.7 ± 63.8 g d(-1). Unlike the PhACs, the musks displayed a high repeatability from one sampling day to the next. The range of PhAC loadings in the influent to WWTPs can vary several orders of magnitude from one day or week to the next, representing a challenge in obtaining data for steady-state modelling purposes. PMID:21783287

  14. The Hydrologic Cycle Distributed Active Archive Center

    NASA Technical Reports Server (NTRS)

    Hardin, Danny M.; Goodman, H. Michael

    1995-01-01

    The Marshall Space Flight Center Distributed Active Archive Center in Huntsville, Alabama supports the acquisition, production, archival and dissemination of data relevant to the study of the global hydrologic cycle. This paper describes the Hydrologic Cycle DAAC, surveys its principle data holdings, addresses future growth, and gives information for accessing the data sets.

  15. Short-term effect of dietary yeast nucleotide supplementation on total and diurnal variation of small intestinal enzyme activities in piglets.

    PubMed

    Sauer, N; Eklund, M; Hoerner, S; Bauer, E; Jezierny, D; Mosenthin, R

    2012-12-01

    A study was carried out to investigate, whether short-term supplementation of dietary yeast nucleotides affects total and diurnal variation of enzyme activities in the small intestine of weaned piglets. Twelve barrows, weaned at 18 d of age (5 kg initial BW), were fitted with a simple T-cannula at the distal ileum. Twice daily (0730 and 1930 h), 6 piglets each received a cereal-soybean (Glycine max) meal-based diet with or without supplementation of 1 g/kg of a yeast nucleotide product in 2 consecutive periods. In each period, digesta samples were collected 6 times at given intervals during 24 h digesta collection. Dietary supplementation with yeast nucleotides did not affect (P > 0.05) total enzyme activities for α-amylase, leucine aminopeptidase (LAP), maltase, and lactase in ileal digesta. Therefore, data of both treatments were pooled to determine diurnal variations in enzyme activities. For α-amylase, a diurnal variation in enzyme activity could be observed (P < 0.05). Variations in diurnal activities of LAP, maltase, and lactase were not observed (P > 0.05). In conclusion, yeast nucleotides do not affect total small intestinal enzyme activities. Independent of diet composition, α-amylase activities may vary over time, with peak flow at 6 h postprandially. PMID:23365322

  16. Prematurity, Birth Weight, and Socioeconomic Status Are Linked to Atypical Diurnal Hypothalamic-Pituitary-Adrenal Axis Activity in Young Adults.

    PubMed

    Winchester, Suzy Barcelos; Sullivan, Mary C; Roberts, Mary B; Granger, Douglas A

    2016-02-01

    In a prospective, case-controlled longitudinal design, 180 preterm and fullterm infants who had been enrolled at birth participated in a comprehensive assessment battery at age 23. Of these, 149 young adults, 34 formerly full-term and 115 formerly preterm (22 healthy preterm, 48 with medical complications, 21 with neurological complications, and 24 small for gestational age) donated five saliva samples from a single day that were assayed for cortisol to assess diurnal variation of the hypothalamic-pituitary-adrenal (HPA) axis. Analyses were conducted to determine whether prematurity category, birth weight, and socioeconomic status were associated with differences in HPA axis function. Pre- and perinatal circumstances associated with prematurity influenced the activity of this environmentally sensitive physiological system. Results are consistent with the theory of Developmental Origins of Health and Disease and highlight a possible mechanism for the link between prematurity and health disparities later in life. PMID:26676400

  17. Modulation of Rubisco Activity during the Diurnal Phases of the Crassulacean Acid Metabolism Plant Kalanchoë daigremontiana.

    PubMed

    Maxwell; Borland; Haslam; Helliker; Roberts; Griffiths

    1999-11-01

    The regulation of Rubisco activity was investigated under high, constant photosynthetic photon flux density during the diurnal phases of Crassulacean acid metabolism in Kalanchoë daigremontiana Hamet et Perr. During phase I, a significant period of nocturnal, C(4)-mediated CO(2) fixation was observed, with the generated malic acid being decarboxylated the following day (phase III). Two periods of daytime atmospheric CO(2) fixation occurred at the beginning (phase II, C(4)-C(3) carboxylation) and end (phase IV, C(3)-C(4) carboxylation) of the day. During the 1st h of the photoperiod, when phosphoenolpyruvate carboxylase was still active, the highest rates of atmospheric CO(2) uptake were observed, coincident with the lowest rates of electron transport and minimal Rubisco activity. Over the next 1 to 2 h of phase II, carbamylation increased rapidly during an initial period of decarboxylation. Maximal carbamylation (70%-80%) was reached 2 h into phase III and was maintained under conditions of elevated CO(2) resulting from malic acid decarboxylation. Initial and total Rubisco activity increased throughout phase III, with maximal activity achieved 9 h into the photoperiod at the beginning of phase IV, as atmospheric CO(2) uptake recommenced. We suggest that the increased enzyme activity supports assimilation under CO(2)-limited conditions at the start of phase IV. The data indicate that Rubisco activity is modulated in-line with intracellular CO(2) supply during the daytime phases of Crassulacean acid metabolism. PMID:10557233

  18. A possible activity cycle in Proxima Centauri

    NASA Astrophysics Data System (ADS)

    Cincunegui, C.; Díaz, R. F.; Mauas, P. J. D.

    2007-01-01

    Context: Several late-type stars present activity cycles resembling the Solar one. This fact has been observed mostly in stars ranging from F to K, i.e., in stars with a radiative core and an outer convective layer. Aims: This work aims at studying whether an activity cycle can be detected in the dM5.5e star Proxima Centauri, which is supposed to be completely convective. Methods: We present periodical medium-resolution echelle observations covering the complete visual range, which were taken at the CASLEO Argentinean Observatory. These observations are distributed over 7 years. We discarded the spectra that present flare activity, and analyze the remaining activity levels using four different statistical techniques to look for a period of activity. Results: We find strong evidence of a cyclic activity, with a period of ~442 days. We also estimate that the Ca ~II S index varies around 130% due to activity variations outside of flares.

  19. A possible activity cycle in Proxima Centauri

    NASA Astrophysics Data System (ADS)

    Cincunegui, C.; Díaz, R. F.; Mauas, P. J. D.

    Several late-type stars (stars with a radiative core and an outer convective layer) present activity cycles resembling the Solar one. This work aims at studying whether an activity cycle can be detected in the dM5.5e star Proxima Centauri, which is supposed to be completely convective. We present periodical medium-resolution echelle observations covering the complete visual range, which were taken at the CASLEO Argentinean Observatory. These observations are distributed along 7 years. We analize the activity levels to look for a period of activity. We find strong evidence of a cyclic activity, with a period of ˜442 days. We also estimated that the Ca II S index varies around 130% due to activity variations outside of flares.

  20. Global water cycle and solar activity variations

    NASA Astrophysics Data System (ADS)

    Al-Tameemi, Muthanna A.; Chukin, Vladimir V.

    2016-05-01

    The water cycle is the most active and most important component in the circulation of global mass and energy in the Earth system. Furthermore, water cycle parameters such as evaporation, precipitation, and precipitable water vapour play a major role in global climate change. In this work, we attempt to determine the impact of solar activity on the global water cycle by analyzing the global monthly values of precipitable water vapour, precipitation, and the Solar Modulation Potential in 1983-2008. The first object of this study was to calculate global evaporation for the period 1983-2008. For this purpose, we determined the water cycle rate from satellite data, and precipitation/evaporation relationship from 10 years of Planet Simulator model data. The second object of our study was to investigate the relationship between the Solar Modulation Potential (solar activity index) and the evaporation for the period 1983-2008. The results showed that there is a relationship between the solar modulation potential and the evaporation values for the period of study. Therefore, we can assume that the solar activity has an impact on the global water cycle.

  1. Observations of Air Quality at the Edge of Kathmandu, Nepal, and the Diurnal Cycle of Air Pollution In and Around the Kathmandu Valley

    NASA Astrophysics Data System (ADS)

    Panday, A. K.; Prinn, R. G.; Regmi, R. P.

    2006-12-01

    The Kathmandu Valley is a bowl-shaped basin in the Nepal Himalaya, with a rapidly growing city surrounded by rice fields and steep terraced and forested mountain slopes. The valley's air quality is influenced by urban and rural emissions, nocturnal pooling of cold air, slope winds, and a daily exchange of air through mountain passes. To understand these processes and to inform air pollution policy in Nepal, we have carried out the most comprehensive study of air pollution in Nepal to date. During the 9-month dry season of 2004-2005, we carried out continuous measurements every minute of carbon monoxide, ozone, PM10, wind speed, wind direction, solar radiation, temperature, and humidity on the eastern edge of Kathmandu city, at a site that daily received air from both the city and rural areas. We recorded the diurnal cycle of the vertical temperature structure and stability with temperature loggers on towers and mountains. A sodar measured the mixed layer height and upper-level winds. 24-hour simultaneous bag sampling campaigns on mountain peaks, passes, the rural valley, and within the city provided glimpses of the spatial patterns of the diurnal cycle of CO -- a useful tracer of anthropogenic emissions. We measured winds on mountain passes and ozone on mountain peaks. At our main measurement site we found a daily-recurring pattern of CO and PM10, with an afternoon low showing rural background levels, even though the arriving air had traversed the city. This was followed by an evening peak starting at sunset, a second low late at night, and a morning peak enhanced by re-circulation. Pollutants emitted in the valley only traveled out of the valley between the late morning and sunset. During winter months, rush hour was outside of this period, enhancing the morning and evening peaks. Within the city, ozone dropped to zero at night. At mid-day we observed an ozone peak enhanced by photochemical production when the air mass that had been stagnant over the city swept

  2. Perturbed rhythmic activation of signaling pathways in mice deficient for Sterol Carrier Protein 2-dependent diurnal lipid transport and metabolism

    PubMed Central

    Jouffe, Céline; Gobet, Cédric; Martin, Eva; Métairon, Sylviane; Morin-Rivron, Delphine; Masoodi, Mojgan; Gachon, Frédéric

    2016-01-01

    Through evolution, most of the living species have acquired a time keeping system to anticipate daily changes caused by the rotation of the Earth. In all of the systems this pacemaker is based on a molecular transcriptional/translational negative feedback loop able to generate rhythmic gene expression with a period close to 24 hours. Recent evidences suggest that post-transcriptional regulations activated mostly by systemic cues play a fundamental role in the process, fine tuning the time keeping system and linking it to animal physiology. Among these signals, we consider the role of lipid transport and metabolism regulated by SCP2. Mice harboring a deletion of the Scp2 locus present a modulated diurnal accumulation of lipids in the liver and a perturbed activation of several signaling pathways including PPARα, SREBP, LRH-1, TORC1 and its upstream regulators. This defect in signaling pathways activation feedbacks upon the clock by lengthening the circadian period of animals through post-translational regulation of core clock regulators, showing that rhythmic lipid transport is a major player in the establishment of rhythmic mRNA and protein expression landscape. PMID:27097688

  3. Perturbed rhythmic activation of signaling pathways in mice deficient for Sterol Carrier Protein 2-dependent diurnal lipid transport and metabolism.

    PubMed

    Jouffe, Céline; Gobet, Cédric; Martin, Eva; Métairon, Sylviane; Morin-Rivron, Delphine; Masoodi, Mojgan; Gachon, Frédéric

    2016-01-01

    Through evolution, most of the living species have acquired a time keeping system to anticipate daily changes caused by the rotation of the Earth. In all of the systems this pacemaker is based on a molecular transcriptional/translational negative feedback loop able to generate rhythmic gene expression with a period close to 24 hours. Recent evidences suggest that post-transcriptional regulations activated mostly by systemic cues play a fundamental role in the process, fine tuning the time keeping system and linking it to animal physiology. Among these signals, we consider the role of lipid transport and metabolism regulated by SCP2. Mice harboring a deletion of the Scp2 locus present a modulated diurnal accumulation of lipids in the liver and a perturbed activation of several signaling pathways including PPARα, SREBP, LRH-1, TORC1 and its upstream regulators. This defect in signaling pathways activation feedbacks upon the clock by lengthening the circadian period of animals through post-translational regulation of core clock regulators, showing that rhythmic lipid transport is a major player in the establishment of rhythmic mRNA and protein expression landscape. PMID:27097688

  4. Diurnal cycle of O[sub 3] and monoterpenes in a coniferous forest: Importance of atmospheric stability, surface exchange, and chemistry

    SciTech Connect

    Johansson, C.; Janson, R.W. )

    1993-03-20

    A one-dimensional model of turbulent diffusion and chemistry has been applied to evaluate measurements of the diurnal variation of O[sub 3] and monoterpenes in a coniferous forest in Sweden. The role of photochemical, meteorological, and surface exchange processes was investigated by studying days characteristic of neutral and stable/unstable conditions, respectively. The atmospheric concentrations and surface exchange rates of O[sub 3], monoterpenes and NO[sub x] were taken from measurements at the site, using chamber techniques for the flux measurements. The model calculations showed the predominant role of turbulent mixing in the observed diurnal variation of O[sub 3] and monoterpenes. The reaction with OH accounted for 50-60% of the terpene loss over a 24-hour period with a well-mixed boundary layer and about 40% when nighttime conditions were stable. Increasing the background O[sub 3] concentration to 80-90 ppbv increased the relative importance of the terpene + O[sub 3] reaction to equal that of the OH reaction. The terpene chemical lifetime was found to be shortest, less than 1 hour, under neutral nighttime conditions when NO[sub 3] concentrations were high. Under stable nighttime conditions, the lower boundary layer became chemically less active due to the depletion of O[sub 3] and NO[sub 3]. Terpene reactions were found to be significant nighttime sinks for O[sub 3] and NO[sub 3] under stable conditions and during periods or at sites of nocturnal terpene emission rates greater than 150 [mu]g/m[sup 2] h. An increase in NO[sub x] concentrations from 0.5 ppbv to 1 and then 5 ppbv, changed O[sub 3] concentrations first up and then down, by not more than 1 ppbv. At terpene emission rates of 50-100 [mu]g (m[sup 2] h)[sup [minus]1], the terpene + OH reaction caused less than 5% of the OH loss near the surface, while at a rate of 1,500 [mu]g (m[sup 2] h)[sup [minus]1], it accounted for up to 30-40% of OH loss. 54 refs., 8 figs., 2 tabs.

  5. How active was solar cycle 22?

    NASA Technical Reports Server (NTRS)

    Hoegy, W. R.; Pesnell, W. D.; Woods, T. N.; Rottman, G. J.

    1993-01-01

    Solar EUV observations from the Langmuir probe on Pioneer Venus Orbiter suggest that at EUV wavelengths solar cycle 22 was more active than solar cycle 21. The Langmuir probe, acting as a photodiode, measured the integrated solar EUV flux over a 13 1/2 year period from January 1979 to June 1992, the longest continuous solar EUV measurement. The Ipe EUV flux correlated very well with the SME measurement of L-alpha during the lifetime of SME and with the UARS SOLSTICE L-alpha from October 1991 to June 1992 when the Ipe measurement ceased. Starting with the peak of solar cycle 21, there was good general agreement of Ipe EUV with the 10.7 cm, Ca K, and He 10830 solar indices, until the onset of solar cycle 22. From 1989 to the start of 1992, the 10.7 cm flux exhibited a broad maximum consisting of two peaks of nearly equal magnitude, whereas Ipe EUV exhibited a strong increase during this time period making the second peak significantly higher than the first. The only solar index that exhibits the same increase in solar activity as Ipe EUV and L-alpha during the cycle 22 peak is the total magnetic flux. The case for high activity during this peak is also supported by the presence of very high solar flare intensity.

  6. Temporal, Spatial, and Diurnal Patterns in Avian Activity at the Shuttle Landing Facility, John F. Kennedy Space Center, Florida, USA

    NASA Technical Reports Server (NTRS)

    Larson, Vickie L.; Rowe, Sean P.; Breininger, David R.

    1997-01-01

    Spatial and temporal patterns in bird abundance within the five-mile airspace at the Shuttle Landing Facility (SLF) on John F. Kennedy Space Center (KSC), Florida, USA were investigated for purposes of quantifying Bird Aircraft Strike Hazards (BASH). The airspace is surrounded by the Merritt Island National Wildlife Refuge (MINWR) which provides habitat for approximately 331 resident and migratory bird species. Potential bird strike hazards were greatest around sunrise and sunset for most avian taxonomic groups, including wading birds, most raptors, pelicans, gulls/terns, shorebirds, and passerines. Turkey Vultures and Black Vultures were identified as a primary threat to aircraft operations and were represented in 33% of the samples. Diurnal vulture activity varied seasonally with the development of air thermals in the airspace surrounding the SLF. Variation in the presence and abundance of migratory species was shown for American Robins, swallows, and several species of shorebirds. Analyses of bird activities provides for planning of avionics operations during periods of low-dsk and allows for risk minimization measures during periods of high-risk.

  7. Nocturnal and diurnal activity of armored suckermouth catfish (Loricariidae: Pterygoplichthys) associated with wintering Florida manatees (Trichechus manatus latirostris)

    USGS Publications Warehouse

    Nico, Leo G.

    2010-01-01

    Several Pterygoplichthys species, members of the Neotropical catfish family Loricariidae, have been widely introduced outside their native ranges. In this paper, I present observations on the diel activity pattern of non-native Pterygoplichthys, tentatively identified as P. disjunctivus, with respect to their attachment and grazing on endangered Florida manatees, Trichechus manatus latirostris. The study was conducted in December 2009 at Volusia Blue Spring, an artesianal spring system in the St. Johns River basin, Florida (USA). Supplemented by information gathered during previous visits to the spring site, this study revealed that adult Pterygoplichthys are active throughout the diel period (day, twilight and night). However, juvenile Pterygoplichthys were largely nocturnal and only at night did they consistently join adults in attaching to manatees. The juveniles generally remain hidden during the day, probably responding to presence of diurnal predators, mainly birds. Differences in diel behaviors among different Pterygoplichthys size classes in Florida are consistent with published observations on loricariids inhabiting clearwater streams within their native ranges.

  8. Diurnal pituitary-adrenal activity during schedule-induced polydipsia of water and ethanol in cynomolgus monkeys (Macaca fascicularis)

    PubMed Central

    Helms, Christa M.; Gonzales, Steven W.; Green, Heather L.; Szeliga, Kendall T.; Rogers, Laura S.M.; Grant, Kathleen A.

    2013-01-01

    Rationale Intermittent delivery of an important commodity (e.g., food pellets) generates excessive behaviors as an adjunct to the schedule of reinforcement (adjunctive behaviors) that are hypothesized to be due to conflict between engaging and escaping a situation where reinforcement is delivered, but at sub-optimal rates. Objectives This study characterized the endocrine correlates during schedule-induced polydipsia (SIP) of water and ethanol using a longitudinal approach in non-human primates. Methods Plasma adrenocorticotropic hormone (ACTH) and cortisol were measured in samples from awake cynomolgus monkeys (Macaca fascicularis, 11 adult males) obtained at the onset, midday and offset of their 12-h light cycle. The monkeys were induced to drink water and ethanol (4% w/v, in water) using a fixed time (FT) 300-s interval schedule of pellet delivery. The induction fluid changed every 30 sessions in the following order: water, 0.5 g/kg ethanol, 1.0 g/kg ethanol, and 1.5 g/kg ethanol. Following induction, ethanol and water were concurrently available for 22 h/d. Results The FT300-s schedule gradually increased ACTH, but not cortisol, during water induction to a plateau sustained throughout ethanol induction in every monkey. Upon termination of the schedule, ACTH decreased to baseline and cortisol below baseline. Diurnal ACTH and cortisol were unrelated to the dose of ethanol, but ACTH rhythm flattened at 0.5 g/kg/d and remained flattened. Conclusions The coincidence of elevated ACTH with the initial experience of drinking to intoxication may have altered the mechanisms involved in the transition to heavy drinking. PMID:23508555

  9. Diurnal variation in cholesterol 7α-hydroxylase activity is determined by the -203A>C polymorphism of the CYP7A1 gene

    PubMed Central

    Vlachová, Miluše; Blahová, Tereza; Lánská, Věra; Leníček, Martin; Piťha, Jan; Vítek, Libor; Kovář, Jan

    2016-01-01

    Aim To determine whether the promoter polymorphism -203A>C of cholesterol-7α-hydroxylase encoding gene (CYP7A1) affects diurnal variation in CYP7A1 enzyme activity. Methods The study included 16 healthy male volunteers – 8 homozygous for -203A and 8 homozygous for the -203C allele of CYP7A1. Three 15-hour examinations (from 7am to 10pm) were carried out for each of the participants: after one-day treatment with cholestyramine; after one-day treatment with chenodeoxycholic acid (CDCA); and a control examination without any treatment. The plasma concentration of 7α-hydroxy-4-cholesten-3-one (C4), a marker of CYP7A1 activity, was determined in all the experiments at 90-min intervals. Results CYP7A1 activity was up-regulated after treatment with cholestyramine and suppressed after treatment with CDCA. There were no differences between -203A and -203C allele carriers in the response of enzyme activity to both drugs. In the control experiment, -203A allele carriers displayed diurnal variation in enzyme activity, whereas CYP7A1 activity did not change in -203C allele carriers. These results were confirmed by modeling the dynamics of C4 using polynomial regression. Conclusion The promoter polymorphism of the CYP7A1 gene has a pronounced impact on diurnal variation in CYP7A1 activity. PMID:27106353

  10. Diurnality of soil nitrous oxide (N2O) emissions

    NASA Astrophysics Data System (ADS)

    Gelfand, I.; Moyer, R.; Poe, A.; Pan, D.; Abraha, M.; Chen, J.; Zondlo, M. A.; Robertson, P.

    2015-12-01

    Soil emissions of nitrous oxide (N2O) are important contributors to the greenhouse gas balance of the atmosphere. Agricultural soils contribute ~65% of anthropogenic N2O emissions. Understanding temporal and spatial variability of N2O emissions from agricultural soils is vital for closure of the global N2O budget and the development of mitigation opportunities. Recent studies have observed higher N2O fluxes during the day and lower at night. Understanding the mechanisms of such diurnality may have important consequences for our understanding of the N cycle. We tested the hypothesis that diurnal cycles are driven by root carbon exudes that stimulate denitrification and therefore N2O production. Alternatively, we considered that the cycle could result from higher afternoon temperatures that accelerate soil microbial activity. We removed all plants from a corn field plot and left another plot untouched. We measured soil N2O emissions in each plot using a standard static chamber technique throughout the corn growing season. And also compared static chamber results to ecosystem level N2O emissions as measured by eddy covariance tower equipped with an open-path N2O sensor. We also measured soil and air temperatures and soil water and inorganic N contents. Soil N2O emissions followed soil inorganic N concentrations and in control plot chambers ranged from 10 μg N m-2 hr-1 before fertilization to 13×103 after fertilization. We found strong diurnal cycles measured by both techniques with emissions low during night and morning hours and high during the afternoon. Corn removal had no effect on diurnality, but had a strong effect on the magnitude of soil N2O emissions. Soil temperature exhibited a weak correlation with soil N2O emissions and could not explain diurnal patterns. Further studies are underway to explore additional mechanisms that might contribute to this potentially important phenomena.

  11. POSSIBLE CHROMOSPHERIC ACTIVITY CYCLES IN AD LEO

    SciTech Connect

    Buccino, Andrea P.; Petrucci, Romina; Mauas, Pablo J. D.; Jofré, Emiliano

    2014-01-20

    AD Leo (GJ 388) is an active dM3 flare star that has been extensively observed both in the quiescent and flaring states. Since this active star is near the fully convective boundary, studying its long-term chromospheric activity in detail could be an appreciable contribution to dynamo theory. Here, using the Lomb-Scargle periodogram, we analyze the Ca II K line-core fluxes derived from CASLEO spectra obtained between 2001 and 2013 and the V magnitude from the ASAS database between 2004 and 2010. From both of these totally independent time series, we obtain a possible activity cycle with a period of approximately seven years and a less significant shorter cycle of approximately two years. A tentative interpretation is that a dynamo operating near the surface could be generating the longer cycle, while a second dynamo operating in the deep convection zone could be responsible for the shorter one. Based on the long duration of our observing program at CASLEO and the fact that we observe different spectral features simultaneously, we also analyze the relation between simultaneous measurements of the Na I index (R{sub D}{sup ′}), Hα, and Ca II K fluxes at different activity levels of AD Leo, including flares.

  12. Seasonal divergence in the interannual responses of Northern Hemisphere vegetation activity to variations in diurnal climate.

    PubMed

    Wu, Xiuchen; Liu, Hongyan; Li, Xiaoyan; Liang, Eryuan; Beck, Pieter S A; Huang, Yongmei

    2016-01-01

    Seasonal asymmetry in the interannual variations in the daytime and nighttime climate in the Northern Hemisphere (NH) is well documented, but its consequences for vegetation activity remain poorly understood. Here, we investigate the interannual responses of vegetation activity to variations of seasonal mean daytime and nighttime climate in NH (>30 °N) during the past decades using remote sensing retrievals, FLUXNET and tree ring data. Despite a generally significant and positive response of vegetation activity to seasonal mean maximum temperature (Tmax) in ~22-25% of the boreal (>50 °N) NH between spring and autumn, spring-summer progressive water limitations appear to decouple vegetation activity from the mean summer Tmax, particularly in climate zones with dry summers. Drought alleviation during autumn results in vegetation recovery from the marked warming-induced drought limitations observed in spring and summer across 24-26% of the temperate NH. Vegetation activity exhibits a pervasively negative correlation with the autumn mean minimum temperature, which is in contrast to the ambiguous patterns observed in spring and summer. Our findings provide new insights into how seasonal asymmetry in the interannual variations in the mean daytime and nighttime climate interacts with water limitations to produce spatiotemporally variable responses of vegetation growth. PMID:26751166

  13. Seasonal divergence in the interannual responses of Northern Hemisphere vegetation activity to variations in diurnal climate

    PubMed Central

    Wu, Xiuchen; Liu, Hongyan; Li, Xiaoyan; Liang, Eryuan; Beck, Pieter S. A.; Huang, Yongmei

    2016-01-01

    Seasonal asymmetry in the interannual variations in the daytime and nighttime climate in the Northern Hemisphere (NH) is well documented, but its consequences for vegetation activity remain poorly understood. Here, we investigate the interannual responses of vegetation activity to variations of seasonal mean daytime and nighttime climate in NH (>30 °N) during the past decades using remote sensing retrievals, FLUXNET and tree ring data. Despite a generally significant and positive response of vegetation activity to seasonal mean maximum temperature () in ~22–25% of the boreal (>50 °N) NH between spring and autumn, spring-summer progressive water limitations appear to decouple vegetation activity from the mean summer , particularly in climate zones with dry summers. Drought alleviation during autumn results in vegetation recovery from the marked warming-induced drought limitations observed in spring and summer across 24–26% of the temperate NH. Vegetation activity exhibits a pervasively negative correlation with the autumn mean minimum temperature, which is in contrast to the ambiguous patterns observed in spring and summer. Our findings provide new insights into how seasonal asymmetry in the interannual variations in the mean daytime and nighttime climate interacts with water limitations to produce spatiotemporally variable responses of vegetation growth. PMID:26751166

  14. Seasonal divergence in the interannual responses of Northern Hemisphere vegetation activity to variations in diurnal climate

    NASA Astrophysics Data System (ADS)

    Wu, Xiuchen; Liu, Hongyan; Li, Xiaoyan; Liang, Eryuan; Beck, Pieter S. A.; Huang, Yongmei

    2016-01-01

    Seasonal asymmetry in the interannual variations in the daytime and nighttime climate in the Northern Hemisphere (NH) is well documented, but its consequences for vegetation activity remain poorly understood. Here, we investigate the interannual responses of vegetation activity to variations of seasonal mean daytime and nighttime climate in NH (>30 °N) during the past decades using remote sensing retrievals, FLUXNET and tree ring data. Despite a generally significant and positive response of vegetation activity to seasonal mean maximum temperature () in ~22-25% of the boreal (>50 °N) NH between spring and autumn, spring-summer progressive water limitations appear to decouple vegetation activity from the mean summer , particularly in climate zones with dry summers. Drought alleviation during autumn results in vegetation recovery from the marked warming-induced drought limitations observed in spring and summer across 24-26% of the temperate NH. Vegetation activity exhibits a pervasively negative correlation with the autumn mean minimum temperature, which is in contrast to the ambiguous patterns observed in spring and summer. Our findings provide new insights into how seasonal asymmetry in the interannual variations in the mean daytime and nighttime climate interacts with water limitations to produce spatiotemporally variable responses of vegetation growth.

  15. Geographic distribution of stomoxyine flies (Diptera: Muscidae) and diurnal activity of Stomoxys calcitrans in Thailand.

    PubMed

    Muenworn, Vithee; Duvallet, Gerard; Thainchum, Krajana; Tuntakom, Siripun; Tanasilchayakul, Somchai; Prabaripai, Atchariya; Akratanakul, Pongthep; Sukonthabhirom, Suprada; Chareonviriyaphap, Theeraphap

    2010-09-01

    Stomoxyine flies (Stomoxys spp.) were collected in 10 localities of Thailand using the Vavoua traps. These localities represented four major ecological settings, as follows: small local dairy farms, large industrial dairy farms, a national park, and one elephant conservation area. Three species of stable flies were identified in the following proportions: Stomoxys calcitrans (91.5%), Stomoxys indicus (7.9%), and Stomoxys sitiens (0.6%). The number of flies collected differed significantly among collection sites (chi2 = 360.15, df=3, P < 0.05). The greatest number of stomoxyine flies was captured in dairy farms. Seasonal and daily activity of S. calcitrans was observed during a 1-yr period at two selected locations (Dairy Farming Promotion Organization of Thailand and Khao Kheow Open Zoo). S. calcitrans was more abundant during the rainy season (March-September), but was not associated with the total rainfall (r2 = 0.0002, P > 0.05). Peak of daily flight activity of males S. calcitrans was at 1000 and 1600 h, whereas females showed an increase of activity all along the day until 1600 h. A better understanding of stomoxyine fly behavior related to patterns of daily activity will facilitate and improve the efficiency of fly control measures in private and government sectors. PMID:20939373

  16. The Heliosphere Through the Solar Activity Cycle

    NASA Technical Reports Server (NTRS)

    Balogh, A.; Lanzerotti, L. J.; Suess, S. T.

    2006-01-01

    Understanding how the Sun changes though its 11-year sunspot cycle and how these changes affect the vast space around the Sun the heliosphere has been one of the principal objectives of space research since the advent of the space age. This book presents the evolution of the heliosphere through an entire solar activity cycle. The last solar cycle (cycle 23) has been the best observed from both the Earth and from a fleet of spacecraft. Of these, the joint ESA-NASA Ulysses probe has provided continuous observations of the state of the heliosphere since 1990 from a unique vantage point, that of a nearly polar orbit around the Sun. Ulysses results affect our understanding of the heliosphere from the interior of the Sun to the interstellar medium - beyond the outer boundary of the heliosphere. Written by scientists closely associated with the Ulysses mission, the book describes and explains the many different aspects of changes in the heliosphere in response to solar activity. In particular, the authors describe the rise in solar ESA and NASA have now unamiously agreed a third extension to operate the highly successful Ulysses spacecraft until March 2008 and, in 2007 and 2008, the European-built space probe will fly over the poles of the Sun for a third time. This will enable Ulysses to add an important chapter to its survey of the high-latitude heliosphere and this additional material would be included in a 2nd edition of this book.

  17. Characteristics of high energy cosmic ray diurnal anisotropy on day-to-day basis

    NASA Astrophysics Data System (ADS)

    Tiwari, C. M.; Tiwari, D. P.

    2008-10-01

    Diurnal variation of cosmic ray intensity for the period of 1989 to 2000 at Kiel, Haleakakla, Rome, Hermanus, Calgary, and Goose Bay neutron monitors has been studied. Frequency histograms are generated for each year by using the daily values of amplitudes and phases. In the present analysis we have derived the yearly mean amplitude and phase of the diurnal variation of cosmic ray intensity. It has been concluded from the analysis that the diurnal amplitude is mostly concentrated in between the amplitude values of 0.1% and 0.4%, whereas the phase of diurnal anisotropy is concentrated in the belt of 100 to 225 degrees. As such, the various characteristics of long-term diurnal variation of cosmic ray intensity for the maxima of solar activity cycle 22 to the next maxima of solar activity cycle 23 have been studied. The minimum amplitudes are apparent for the minimum solar activity periods starting from 1995 and up to 1997 at Kiel, Haleakakla, Rome, Hermanus, Calgary and Goose Bay stations. The diurnal amplitude has been found to have almost recovered to its values observed during 1989 to 1990. It is also seen that the diurnal amplitudes are much larger by a factor of two at high/middle latitude stations as compared to that for low latitude stations, where the amplitudes are even ˜01% or less during 1996. The phase is significantly earlier during 1996 and 1997 with some significant change starting in 1995. As such, competitive is a continuous decreasing trend in the diurnal phase with smaller change at high/middle latitude and significantly much larger change at low latitudes.

  18. Recent Advances in GEO Water Cycle Activities

    NASA Astrophysics Data System (ADS)

    Lawford, R. G.

    2009-12-01

    Over the past few years GEO (Group on Earth Observations) efforts within the Water Societal Benefit Area (SBA) have been coordinated by the Science Committee of the former Integrated Global Observing Strategy Partnership (IGOS-P) IGWCO (Integrated Global Water Cycle Observations) theme. Within this framework a number of projects related to data system design, product development, and capacity building are being carried out. GEO has recently consolidated the Water SBA activities into three tasks, namely Droughts, Floods and Water Resource Management; Capacity Building for Water Resource Management (in Asia, Africa and the Americas); and Integrated Products for Water Resource Management and Research. In order to strengthen interactions with the GEO and its User Interface Committee, a Water Cycle Community of Practice (COP) was initiated. In addition, within the past year, the IGWCO Science Committee has decided to also function as a Community of Practice in collaboration with the existing Water Cycle COP. This overview will provide background and an update on the GEO Water SBA activities with an emphasis of the way in which these activities are being integrated within the three tasks. It will also describe activities that are planned for 2010 to facilitate this integration. Recent advances related to drought monitoring, capacity and network building, and observational and data systems will be highlighted. New water-related activities arising from collaborations between US GEO and Canada GEO, and through activities within the GEO Architecture and Data Committee, will also be described. This presentation will conclude with a longer-term outlook for water within the GEO framework and provide some guidance for interested experts on how they can become involved in helping to implement these plans.

  19. Diurnally driven scaling properties of Amazonian rainfall fields: Fourier spectra and order-q statistical moments

    NASA Astrophysics Data System (ADS)

    Morales, JuliáN. E.; Poveda, GermáN.

    2009-06-01

    The influence of the diurnal cycle on spatial scaling properties of Amazonian rainfall fields is investigated using data gathered during the January-February 1999 Wet Season Atmospheric Meso-scale Campaign in the state of Rondonia (Brazil, SW Amazonia). Most intense precipitation events with large spatial coverage occur during early afternoon. Amplitudes of average and maximum intensity diurnal cycles are higher during the easterly than during the westerly atmospheric regime. The diurnal cycle of average rainfall occupancy exhibits a significantly larger amplitude during the westerly regime. Storms exhibit power law Fourier spectra, E(k) = ck-β, with two scaling regimes characterized by different scaling exponents (β1 and β2), separated at a critical distance, which depends on the spatial extent of rainfall organization. Inversely correlated diurnal cycles for β1 and β2 reflect rainfall organization patterns at different spatial scales through the 24-h period. The break occurs at smaller (larger) spatial scales during the morning (afternoon-evening). Average values of c and β exhibit inversely related diurnal cycles, and different behavior during either atmospheric regime. Order-q statistical moments indicate multiscaling of rainfall fields. Departures from simple scaling are also driven by the diurnal cycle, reflecting differences in convective activity and the spatial organization of rainfall throughout the 24-h cycle. Departures from simple scaling are dependent on the moment order q. Clear-cut differences between the estimated order-q statistical moments appear during both atmospheric regimes. These results shed light toward linking physical processes with statistics in Amazonian storms.

  20. Stochastic cycle selection in active flow networks.

    PubMed

    Woodhouse, Francis G; Forrow, Aden; Fawcett, Joanna B; Dunkel, Jörn

    2016-07-19

    Active biological flow networks pervade nature and span a wide range of scales, from arterial blood vessels and bronchial mucus transport in humans to bacterial flow through porous media or plasmodial shuttle streaming in slime molds. Despite their ubiquity, little is known about the self-organization principles that govern flow statistics in such nonequilibrium networks. Here we connect concepts from lattice field theory, graph theory, and transition rate theory to understand how topology controls dynamics in a generic model for actively driven flow on a network. Our combined theoretical and numerical analysis identifies symmetry-based rules that make it possible to classify and predict the selection statistics of complex flow cycles from the network topology. The conceptual framework developed here is applicable to a broad class of biological and nonbiological far-from-equilibrium networks, including actively controlled information flows, and establishes a correspondence between active flow networks and generalized ice-type models. PMID:27382186

  1. GEO Water Cycle Activities and Plans

    NASA Astrophysics Data System (ADS)

    Lawford, R.; Koike, T.; Ishida, C.; Grabs, W.

    2008-12-01

    The Group on Earth Observations (GEO) consists of more than 70 countries and 40 international organizations which are working together to develop the Global Earth Observation System of Systems (GEOSS). Since its launch in 2004, GEO has stimulated a wide range of activities related to data systems and their architecture, the development of science and technology to support observational programs, user interactions and interfaces, and capacity building. GEO tasks directed at Water Resources Management, one of the nine GEO Societal Benefit areas, are an integral part of these developments. They draw heavily upon the activities of the Integrated Global Water Cycle Observations (IGWCO) theme and on the activities and infrastructure provided through GEO and its committees. Within the GEO framework the water related activities have been focused on four specific tasks namely integrated data set development; information for floods, droughts and water management; water quality, and capacity building. Currently these efforts are being facilitated by the IGWCO theme that was formed under the former Integrated Global Observing Strategy Partnership (IGOS-P). With the dissolution of this partnership, other mechanisms, including the GEO Water Cycle Community of Practice, are being considered as new opportunitites for coordinating the work of the theme and the water-related GEO tasks. This talk provides a description of the GEO water tasks and reviews the progress that has been made in addressing them. It also provides a perspective on new opportunities and briefly describes some of the mechanisms, such as the Water Cycle Community of Practice, that could be expanded to coordinate a more comprehensive set of water tasks and greater community involvement.

  2. Role of eastward propagating convection systems in the diurnal cycle and seasonal mean summertime rainfall over the U. S. Great Plains

    SciTech Connect

    Jiang, X; Lau, N C; Klein, S A

    2006-06-07

    By diagnosing the 3-hourly North American Regional Reanalysis rainfall dataset for the 1979-2003 period, it is illustrated that the eastward propagation of convection systems from the Rockies to the Great Plains plays an essential role for the warm season climate over the central U.S. This eastward propagating mode could be the deciding factor for the observed nocturnal rainfall peak over the Great Plains. The results also suggest that nearly half of the total summer mean rainfall over this region is associated with these propagating convection systems. For instance, the extreme wet condition of the 1993 summer may be attributed to the frequent occurrence of propagating convection events and enhanced diurnal rainfall amplitude over the Great Plains. Thus, proper representation of this important propagating component in GCMs is essential for simulating the diurnal and seasonal mean characteristics of summertime rainfall over the central US.

  3. (Un-)expected nocturnal activity in "Diurnal" Lemur catta supports cathemerality as one of the key adaptations of the lemurid radiation.

    PubMed

    Donati, Giuseppe; Santini, Luca; Razafindramanana, Josia; Boitani, Luigi; Borgognini-Tarli, Silvana

    2013-01-01

    The ability to operate during the day and at night (i.e., cathemerality) is common among mammals but has rarely been identified in primates. Adaptive hypotheses assume that cathemerality represents a stable adaptation in primates, while nonadaptive hypotheses propose that it is the result of an evolutionary disequilibrium arising from human impacts on natural habitats. Madagascar offers a unique opportunity to study the evolution of activity patterns as there we find a monophyletic primate radiation that shows nocturnal, diurnal, and cathemeral patterns. However, when and why cathemeral activity evolved in lemurs is the subject of intense debate. Thus far, this activity pattern has been regularly observed in only three lemurid genera but the actual number of lemur species exhibiting this activity is as yet unknown. Here we show that the ring-tailed lemur, Lemur catta, a species previously considered to be diurnal, can in fact be cathemeral in the wild. In neighboring but distinct forest areas these lemurs exhibited either mainly diurnal or cathemeral activity. We found that, as in other cathemeral lemurs, activity was entrained by photoperiod and masked by nocturnal luminosity. Our results confirm the relationship between transitional eye anatomy and physiology and 24-h activity, thus supporting the adaptive scenario. Also, on the basis of the most recent strepsirrhine phylogenetic reconstruction, using parsimony criterion, our findings suggest pushing back the emergence of cathemerality to stem lemurids. Flexible activity over 24-h could thus have been one of the key adaptations of the early lemurid radiation possibly driven by Madagascar's island ecology. PMID:23180596

  4. Coronal Activity and Extended Solar Cycles

    NASA Astrophysics Data System (ADS)

    Altrock, R. C.

    2012-12-01

    Wilson et al. (1988, Nature 333, 748) discussed a number of solar parameters, which appear at high latitudes and gradually migrate towards the equator, merging with the sunspot "butterfly diagram". They found that this concept had been identified by earlier investigators extending back to 1957. They named this process the "Extended Solar Cycle" (ESC). Altrock (1997, Solar Phys. 170, 411) found that this process continued in Fe XIV 530.3 nm emission features. In cycles 21 - 23 solar maximum occurred when the number of Fe XIV emission regions per day > 0.19 (averaged over 365 days and both hemispheres) first reached latitudes 18°, 21° and 21°, for an average of 20° ± 1.7°. Other recent studies have shown that Torsional Oscillation (TO) negative-shear zones are co-located with the ESC from at least 50° down to the equator and also in the zones where the Rush to the Poles occur. These phenomena indicate that coronal activity occurring up to 50° and higher latitudes is related to TO shear zones, another indicator that the ESC is an important solar process. Another high-latitude process, which appears to be connected with the ESC, is the "Rush to the Poles" ("Rush") of polar crown prominences and their associated coronal emission, including Fe XIV. The Rush is is a harbinger of solar maximum (cf. Altrock, 2003, Solar Phys. 216, 343). Solar maximum in cycles 21 - 23 occurred when the center line of the Rush reached a critical latitude. These latitudes were 76°, 74° and 78°, respectively, for an average of 76° ± 2°. Applying the above conclusions to Cycle 24 is difficult due to the unusual nature of this cycle. Cycle 24 displays an intermittent "Rush" that is only well-defined in the northern hemisphere. In 2009 an initial slope of 4.6°/yr was found in the north, compared to an average of 9.4 ± 1.7 °/yr in the previous three cycles. This early fit to the Rush would have reached 76° at 2014.6. However, in 2010 the slope increased to 7.5°/yr (an increase

  5. Reproducibility of summertime diurnal precipitation over northern Eurasia simulated by CMIP5 climate models

    NASA Astrophysics Data System (ADS)

    Hirota, N.; Takayabu, Y. N.

    2015-12-01

    Reproducibility of diurnal precipitation over northern Eurasia simulated by CMIP5 climate models in their historical runs were evaluated, in comparison with station data (NCDC-9813) and satellite data (GSMaP-V5). We first calculated diurnal cycles by averaging precipitation at each local solar time (LST) in June-July-August during 1981-2000 over the continent of northern Eurasia (0-180E, 45-90N). Then we examined occurrence time of maximum precipitation and a contribution of diurnally varying precipitation to the total precipitation.The contribution of diurnal precipitation was about 21% in both NCDC-9813 and GSMaP-V5. The maximum precipitation occurred at 18LST in NCDC-9813 but 16LST in GSMaP-V5, indicating some uncertainties even in the observational datasets. The diurnal contribution of the CMIP5 models varied largely from 11% to 62%, and their timing of the precipitation maximum ranged from 11LST to 20LST. Interestingly, the contribution and the timing had strong negative correlation of -0.65. The models with larger diurnal precipitation showed precipitation maximum earlier around noon. Next, we compared sensitivity of precipitation to surface temperature and tropospheric humidity between 5 models with large diurnal precipitation (LDMs) and 5 models with small diurnal precipitation (SDMs). Precipitation in LDMs showed high sensitivity to surface temperature, indicating its close relationship with local instability. On the other hand, synoptic disturbances were more active in SDMs with a dominant role of the large scale condensation, and precipitation in SDMs was more related with tropospheric moisture. Therefore, the relative importance of the local instability and the synoptic disturbances was suggested to be an important factor in determining the contribution and timing of the diurnal precipitation. Acknowledgment: This study is supported by Green Network of Excellence (GRENE) Program by the Ministry of Education, Culture, Sports, Science and Technology

  6. PDF-modulated visual inputs and cryptochrome define diurnal behavior in Drosophila.

    PubMed

    Cusumano, Paola; Klarsfeld, André; Chélot, Elisabeth; Picot, Marie; Richier, Benjamin; Rouyer, François

    2009-11-01

    Morning and evening circadian oscillators control the bimodal activity of Drosophila in light-dark cycles. The lateral neurons evening oscillator (LN-EO) is important for promoting diurnal activity at dusk. We found that the LN-EO autonomously synchronized to light-dark cycles through either the cryptochrome (CRY) that it expressed or the visual system. In conditions in which CRY was not activated, flies depleted for pigment-dispersing factor (PDF) or its receptor lost the evening activity and displayed reversed PER oscillations in the LN-EO. Rescue experiments indicated that normal PER cycling and the presence of evening activity relied on PDF secretion from the large ventral lateral neurons and PDF receptor function in the LN-EO. The LN-EO thus integrates light inputs and PDF signaling to control Drosophila diurnal behavior, revealing a new clock-independent function for PDF. PMID:19820704

  7. Flip-flop cycles in solar and stellar activity

    NASA Astrophysics Data System (ADS)

    Berdyugina, S. V.

    2006-08-01

    Doppler images and long time series of photometric observations of cool active stars reveal permanent active longitudes on their surfaces. They are found to alternate their dominant activity quasi-periodically which indicates a new type of the activity cycles, flip-flop cycles. In this talk I will review properties of active longitudes and flip-flop cycles on different types of active stars including the Sun.

  8. Activity Cycles in the Hyades and Praesepe

    NASA Astrophysics Data System (ADS)

    Baliunas, Sallie L.

    The giant stars in the Hyades present a well-studied group of stars of spectral type KO III. Their optical properties are quite similar, if not identical. All rotate with the same, slow period. Yet their chromospheric and coronal emission is different one from another, by as much as a factor of ten. We conjecture that this disparity results from sampling during different phases of long-term activity cycles which are present among dwarf stars. Some variation on a three-year timescale has been observed, as well as during phases of rotation modulation, however, at levels too small to explain the discrepancy of the emission strengths between the stars. We propose to investigate the range of chromospheric activity from these giants which are similar in the visible three ways: (a) reobserve the Hyades to search for variability on at least a seven-year timescale; (b) reobserve another young cluster, Praesepe, with four KO III stars similar to those in the Hyades to search for variability on a five-year timescale; (c) extend the sampling to four Hyades moving group stars with similar photospheric properties. The ultraviolet spectra provided by IUE represent the longest time frame, seven years, over which to search for long-term activity variations.

  9. The sleep-wake cycle and motor activity, but not temperature, are disrupted over the light-dark cycle in mice genetically depleted of serotonin

    PubMed Central

    Solarewicz, Julia Z.; Angoa-Perez, Mariana; Kuhn, Donald M.; Mateika, Jason H.

    2016-01-01

    We examined the role that serotonin has in the modulation of sleep and wakefulness across a 12-h:12-h light-dark cycle and determined whether temperature and motor activity are directly responsible for potential disruptions to arousal state. Telemetry transmitters were implanted in 24 wild-type mice (Tph2+/+) and 24 mice with a null mutation for tryptophan hydroxylase 2 (Tph2−/−). After surgery, electroencephalography, core body temperature, and motor activity were recorded for 24 h. Temperature for a given arousal state (quiet and active wake, non-rapid eye movement, and paradoxical sleep) was similar in the Tph2+/+ and Tph2−/− mice across the light-dark cycle. The percentage of time spent in active wakefulness, along with motor activity, was decreased in the Tph2+/+ compared with the Tph2−/− mice at the start and end of the dark cycle. This difference persisted into the light cycle. In contrast, the time spent in a given arousal state was similar at the remaining time points. Despite this similarity, periods of non-rapid-eye-movement sleep and wakefulness were less consolidated in the Tph2+/+ compared with the Tph2−/− mice throughout the light-dark cycle. We conclude that the depletion of serotonin does not disrupt the diurnal variation in the sleep-wake cycle, motor activity, and temperature. However, serotonin may suppress photic and nonphotic inputs that manifest at light-dark transitions and serve to shorten the ultraradian duration of wakefulness and non-rapid-eye-movement sleep. Finally, alterations in the sleep-wake cycle following depletion of serotonin are unrelated to disruptions in the modulation of temperature. PMID:25394829

  10. The sleep-wake cycle and motor activity, but not temperature, are disrupted over the light-dark cycle in mice genetically depleted of serotonin.

    PubMed

    Solarewicz, Julia Z; Angoa-Perez, Mariana; Kuhn, Donald M; Mateika, Jason H

    2015-01-01

    We examined the role that serotonin has in the modulation of sleep and wakefulness across a 12-h:12-h light-dark cycle and determined whether temperature and motor activity are directly responsible for potential disruptions to arousal state. Telemetry transmitters were implanted in 24 wild-type mice (Tph2(+/+)) and 24 mice with a null mutation for tryptophan hydroxylase 2 (Tph2(-/-)). After surgery, electroencephalography, core body temperature, and motor activity were recorded for 24 h. Temperature for a given arousal state (quiet and active wake, non-rapid eye movement, and paradoxical sleep) was similar in the Tph2(+/+) and Tph2(-/-) mice across the light-dark cycle. The percentage of time spent in active wakefulness, along with motor activity, was decreased in the Tph2(+/+) compared with the Tph2(-/-) mice at the start and end of the dark cycle. This difference persisted into the light cycle. In contrast, the time spent in a given arousal state was similar at the remaining time points. Despite this similarity, periods of non-rapid-eye-movement sleep and wakefulness were less consolidated in the Tph2(+/+) compared with the Tph2(-/-) mice throughout the light-dark cycle. We conclude that the depletion of serotonin does not disrupt the diurnal variation in the sleep-wake cycle, motor activity, and temperature. However, serotonin may suppress photic and nonphotic inputs that manifest at light-dark transitions and serve to shorten the ultraradian duration of wakefulness and non-rapid-eye-movement sleep. Finally, alterations in the sleep-wake cycle following depletion of serotonin are unrelated to disruptions in the modulation of temperature. PMID:25394829

  11. Climatology of diurnal tide and its long-term variability in the lower middle atmosphere over a tropical station

    NASA Astrophysics Data System (ADS)

    Kumar, P. Vinay; Dutta, Gopa; Mohammad, Salauddin; Rao, B. Venkateswara

    2016-07-01

    ECMWF reanalysis (ERA-interim) data of winds for two solar cycles (1991-2012) are harmonically analyzed to delineate the characteristics and variability of diurnal tide over a tropical site (13.5° N, 79.5° E). The diurnal cycle horizontal winds measured by Gadanki (13.5° N, 79.2° E) mesosphere-stratosphere-troposphere (MST) radar between May 2005 and April 2006 have been used to compute 24 h tidal amplitudes and phases and compared with the corresponding results obtained from ERA winds. The climatological diurnal tidal amplitudes and phases have been estimated from surface to ˜33 km using ERA interim data. The amplitudes and phases obtained in the present study are found to compare reasonably well with Global Scale Wave Model (GSWM-09). Diurnal tides show larger amplitudes in the lower troposphere below 5 km during summer and in the mid-stratosphere mainly during equinoctial months and early winter. Water vapor and convection in the lower troposphere are observed to play major roles in exciting 24-h tide. Correlations between diurnal amplitude and integrated water vapor and between diurnal amplitude and outgoing longwave radiation (OLR) are 0.59 and -0.34, respectively. Ozone mixing ratio correlates (ρ = 0.66) well with diurnal amplitude and shows annual variation in the troposphere whereas semi-annual variation is observed at stratospheric heights with stronger peaks in equinoctial months. A clear annual variation of diurnal amplitude is displayed in the troposphere and interannual variability becomes prominent in the stratosphere which could be partly due to the influence of equatorial stratospheric QBO. The influence of solar activity on diurnal oscillations is found to be insignificant.

  12. A decrease in solar and geomagnetic activity from cycle 19 to cycle 24

    NASA Astrophysics Data System (ADS)

    Gvishiani, A. D.; Starostenko, V. I.; Sumaruk, Yu. P.; Soloviev, A. A.; Legostaeva, O. V.

    2015-05-01

    Variations in the solar and geomagnetic activity from cycle 19 to cycle 24 were considered based on data from the magnetic observatories of the Russian-Ukrainian INTERMAGNET segment and international centers of data on solar-terrestrial physics. It has been indicated that activity decreases over the course of time. This is especially evident during the cycle 24 growth phase. The possible causes and consequences of a decrease in geomagnetic activity were analyzed.

  13. Heterogeneous Boundary Layers through the Diurnal Cycle: Evaluation of the WRF Wind Farm Parameterization using Scanning Lidar Observations and Wind Turbine Power Measurements during a Range of Stability Conditions

    NASA Astrophysics Data System (ADS)

    Lundquist, J. K.

    2015-12-01

    As wind energy deployment increases, questions arise regarding impacts on local climates and how these impacts evolve with the diurnal cycle of the boundary layer. Satellite observations suggest nocturnal increases of surface temperatures, and measurements of turbine wakes document stronger and more persistent reductions of wind speed and increases in turbulence downwind of turbines during stable conditions. Validations of mesoscale parameterizations of these effects have been constrained to idealized conditions defined by neutrally-stratified conditions and/or limited wind directions and wind speeds, or by comparison to idealized large-eddy simulations. Synthesis of conventional meteorological measurements and unconventional measurements can offer unique insights for validating models over a large heterogeneous domain. The CWEX-13 field experiment provides an extensive dataset for such validation at spatial scales on the order of 10 km in a range of atmospheric stability and wind conditions. CWEX-13 took place within a 300 MW wind farm in central Iowa during summer 2013 and featured strong diurnal cycles. The wind turbines are sited irregularly, creating a heterogenous "canopy". Three profiling lidars, numerous surface flux stations, and a scanning lidar sampled wakes from multiple turbines. Further, the wind farm owner/operator has provided access to turbine power production and wind speed measurement data for model validation, providing ~ 200 measurements of proxies that integrate the wind profile over the rotor disk, from 40 m to 120 m above the surface. Building on previous work that identified optimal physics options, grid configurations, and boundary condition data sets by comparison to lidar wind profile measurements, we execute simulations with the WRF Wind Farm Parameterization for a ten-day period featuring moderate winds and strong diurnal cycles. We evaluate simulations with different modeling choices (e.g., vertical resolution, approaches to

  14. Long term changes in cosmic ray diurnal variations observed by ion chambers in Hong Kong and Japan

    NASA Technical Reports Server (NTRS)

    Chuang, L. S.; Kusunose, M.; Wada, M.

    1985-01-01

    Yearly average solar diurnal variations of cosmic ray ion chamber data are inspected from a view point of the eleven and the 22 year solar activity cycle modulations. Ion chamber data and neutron data from various stations are added. From an inspection of observed data, a simple approximation that the 11 year and the 22 year variations of the solar diurnal variation are along 18-hour and 12-hour axes, respectively is proposed. The 18-hour component of diurnal variation in the 11 year cycle increases toward the solar active years. The 12-hour component is enhanced when the solar general magnetic field is parallel to the rotation vector, and is almost zero for the other state. The transition occurs when the amplitude of the 18-hour component is greater owing to the transition of the field during the maximum phase of solar activity. The 22 year shift is consistent with the drift modulation model in heliosphere.

  15. A prediction of geomagnetic activity for solar cycle 23

    NASA Astrophysics Data System (ADS)

    Cliver, E. W.; Ling, A. G.; Wise, J. E.; Lanzerotti, L. J.

    1999-04-01

    Using a database of 13 solar cycles of geomagnetic aa data, we obtained correlations between cycle averages of geomagnetic activity (and sunspot number) and the numbers of days with disturbance levels above certain aa thresholds. We then used a precursor-type relation to predict an average aa index of 23.1 nT for cycle 23 and inserted this average aa value into the above correlations to forecast the integral size distribution of geomagnetic activity for the new cycle. The predicted size distribution is similar to that observed for cycles 21 and 22 but most closely resembles that of solar cycle 18 (1944-1954), which was slightly smaller than cycles 21 and 22. Our prediction agrees reasonably well with the ``climatology-based'' forecast made by the intergovernmental panel tasked to predict geomagnetic activity for the coming solar cycle and is significantly different from their ``precursor-based'' prediction.

  16. The contribution of the pineal gland on daily rhythms and masking in diurnal grass rats, Arvicanthis niloticus.

    PubMed

    Shuboni, Dorela D; Agha, Amna A; Groves, Thomas K H; Gall, Andrew J

    2016-07-01

    Melatonin is a hormone rhythmically secreted at night by the pineal gland in vertebrates. In diurnal mammals, melatonin is present during the inactive phase of the rest/activity cycle, and in primates it directly facilitates sleep and decreases body temperature. However, the role of the pineal gland for the promotion of sleep at night has not yet been studied in non-primate diurnal mammalian species. Here, the authors directly examined the hypothesis that the pineal gland contributes to diurnality in Nile grass rats by decreasing activity and increasing sleep at night, and that this could occur via effects on circadian mechanisms or masking, or both. Removing the pineal gland had no effect on the hourly distribution of activity across a 12:12 light-dark (LD) cycle or on the patterns of sleep-like behavior at night. Masking effects of light at night on activity were also not significantly different in pinealectomized and control grass rats, as 1h pulses of light stimulated increases in activity of sham and pinealectomized animals to a similar extent. In addition, the circadian regulation of activity was unaffected by the surgical condition of the animals. Our results suggest that the pineal gland does not contribute to diurnality in the grass rat, thus highlighting the complexity of temporal niche transitions. The current data raise interesting questions about how and why genetic and neural mechanisms linking melatonin to sleep regulatory systems might vary among mammals that reached a diurnal niche via parallel and independent pathways. PMID:27038859

  17. Why be diurnal? Or, why not be cathemeral?

    PubMed

    Hill, R A

    2006-01-01

    As a behavioural strategy, cathemerality is thought to confer considerable advantages by allowing animals to extend activity flexibly into either the diurnal or nocturnal phase in response to the prevailing ecological conditions. Factors such as temperature, access to food sources and minimising the risk of predation are all thought to be important in promoting cathemerality, although previous studies have produced inconsistent results. This paper adopts a different approach by first asking whether an obligate diurnal species, the chacma baboon (Papio hamadryas ursinus), exhibits seasonal variation in behavioural flexibility in response to annual cycles of day length. While short day lengths are an important constraint on the activity of the baboons at De Hoop Nature Reserve, South Africa, long summer days permit considerable flexibility in thermoregulatory response, diet selection and patterns of habitat choice. Given that baboons adapt flexibly in response to a relaxation of time constraints, the question thus arises as to why diurnal and nocturnal primates do not adopt cathemeral activity patterns when time is constrained? For baboons, the costs of predation appear to prohibit exploitation of the nocturnal phase and it is likely that such constraints are true of most primates. It thus follows that Madagascar's predatory environment must in some way permit or select for a cathemeral lifestyle. The importance of the predation by fossa (Cryptoprocta ferox) on the evolution of cathemerality is discussed. PMID:16415578

  18. Cold and hunger induce diurnality in a nocturnal mammal.

    PubMed

    van der Vinne, Vincent; Riede, Sjaak J; Gorter, Jenke A; Eijer, Willem G; Sellix, Michael T; Menaker, Michael; Daan, Serge; Pilorz, Violetta; Hut, Roelof A

    2014-10-21

    The mammalian circadian system synchronizes daily timing of activity and rest with the environmental light-dark cycle. Although the underlying molecular oscillatory mechanism is well studied, factors that influence phenotypic plasticity in daily activity patterns (temporal niche switching, chronotype) are presently unknown. Molecular evidence suggests that metabolism may influence the circadian molecular clock, but evidence at the level of the organism is lacking. Here we show that a metabolic challenge by cold and hunger induces diurnality in otherwise nocturnal mice. Lowering ambient temperature changes the phase of circadian light-dark entrainment in mice by increasing daytime and decreasing nighttime activity. This effect is further enhanced by simulated food shortage, which identifies metabolic balance as the underlying common factor influencing circadian organization. Clock gene expression analysis shows that the underlying neuronal mechanism is downstream from or parallel to the main circadian pacemaker (the hypothalamic suprachiasmatic nucleus) and that the behavioral phenotype is accompanied by phase adjustment of peripheral tissues. These findings indicate that nocturnal mammals can display considerable plasticity in circadian organization and may adopt a diurnal phenotype when energetically challenged. Our previously defined circadian thermoenergetics hypothesis proposes that such circadian plasticity, which naturally occurs in nocturnal mammals, reflects adaptive maintenance of energy balance. Quantification of energy expenditure shows that diurnality under natural conditions reduces thermoregulatory costs in small burrowing mammals like mice. Metabolic feedback on circadian organization thus provides functional benefits by reducing energy expenditure. Our findings may help to clarify relationships between sleep-wake patterns and metabolic phenotypes in humans. PMID:25288753

  19. Improving Motor Activity Assessment in Depression: Which Sensor Placement, Analytic Strategy and Diurnal Time Frame Are Most Powerful in Distinguishing Patients from Controls and Monitoring Treatment Effects

    PubMed Central

    Deuschle, Michael; Gilles, Maria; Hill, Holger; Limberger, Matthias F.; Ebner-Priemer, Ulrich W.

    2015-01-01

    Background Abnormalities in motor activity represent a central feature in major depressive disorder. However, measurement issues are poorly understood, limiting the use of objective measurement of motor activity for diagnostics and treatment monitoring. Methods To improve measurement issues, especially sensor placement, analytic strategies and diurnal effects, we assessed motor activity in depressed patients at the beginning (MD; n=27) and after anti-depressive treatment (MD-post; n=18) as well as in healthy controls (HC; n=16) using wrist- and chest-worn accelerometers. We performed multiple analyses regarding sensor placements, extracted features, diurnal variation, motion patterns and posture to clarify which parameters are most powerful in distinguishing patients from controls and monitoring treatment effects. Results Whereas most feature-placement combinations revealed significant differences between groups, acceleration (wrist) distinguished MD from HC (d=1.39) best. Frequency (vertical axis chest) additionally differentiated groups in a logistic regression model (R2=0.54). Accordingly, both amplitude (d=1.16) and frequency (d=1.04) showed alterations, indicating reduced and decelerated motor activity. Differences between MD and HC in gestures (d=0.97) and walking (d=1.53) were found by data analysis from the wrist sensor. Comparison of motor activity at the beginning and after MD-treatment largely confirms our findings. Limitations Sample size was small, but sufficient for the given effect sizes. Comparison of depressed in-patients with non-hospitalized controls might have limited motor activity differences between groups. Conclusions Measurement of wrist-acceleration can be recommended as a basic technique to capture motor activity in depressed patients as it records whole body movement and gestures. Detailed analyses showed differences in amplitude and frequency denoting that depressed patients walked less and slower. PMID:25885258

  20. Diurnal variations from muon data at Takeyama underground station

    NASA Technical Reports Server (NTRS)

    Takahashi, K.; Imai, K.; Imai, T.; Kudo, S.; Wada, M.

    1985-01-01

    An underground station, Takeyama, is introduced, and some results of the solar diurnal and semi-diurnal variations for the period between 1967 and 1984 are presented. There are clear tendencies of double and single solar cycle variations in the daily variations which are in good accord with those detected by other underground and neutron monitor observations.

  1. An 'In Situ' Calibration-Correction Procedure (KCICLO) Based on AOD Diurnal Cycle: Comparative Results Between AERONET and Reprocessed (KCICLO method) AOD-Alpha Data Series at El Arenosillo, Spain

    SciTech Connect

    Cachorro, V. E.; Toledano, C.; Sorribas, M.; Berjon, A.; de Frutos, A. M.; Laulainen, Nels S.

    2008-01-31

    A comparative evaluation is carried out for nearly 5 years (February 2000 to May 2004) of data of aerosol optical depth (AOD) measured at the Aerosol Robotic Network (AERONET) site El Arenosillo (Huelva, southwestern Spain). The AERONET database and the reprocessed data set using a new correction procedure, which we call the KCICLO method, are compared with respect to the aerosol local climatology. The cause and necessity of AOD reprocessing were due to the existence of an observed fictitious diurnal cycle (including negative values) because of a deficient calibration as explained in detail in the companion paper (V. E. Cachorro et al., submitted manuscript, 2007). The derived alpha Ångström coefficient is also compared, as it appears to be an excellent indicator of the AOD data quality, because of its sensitivity to AOD variations and errors. Some illustrative cases show the influence of this fictitious diurnal cycle on the shape and values of diurnal variations of the AOD (or alpha), reaching differences as high as 100%, and the improvement resulting from using the KCICLO method. Absolute and relative differences are evaluated from the overall average of AOD and alpha coefficient of AERONET and KCICLO data series, making an exhaustive analysis for each spectral channel and for every photometer separately. Although great variability is shown for each filter and each photometer, apart from photometer 114 data that did not reach level 2.0, the discrepancy in the AOD local climatology in the four filters varies as a whole from 2.3% to 8.5% (2.4% for alpha coefficient). These values show a considerable reduction because of the compensating effect between the different photometers (positive or negative bias), and several jumps that break the continuity of the data series are observed. When monthly and yearly averages are analyzed, the differences are considerably reduced in such a way that the local climatology is not substantially affected, but we must be cautious

  2. Seasonal and diurnal variation of geomagnetic activity: Russell-McPherron effect during different IMF polarity and/or extreme solar wind conditions

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Zong, Q.-G.

    2012-11-01

    The Russell-McPherron (R-M) effect is one of the most prevailing hypotheses accounting for semiannual variation of geomagnetic activity. To validate the R-M effect and investigate the difference of geomagnetic activity variation under different interplanetary magnetic field (IMF) polarity and during extreme solar wind conditions (interplanetary shock), we have analyzed 42 years interplanetary magnetic field and geomagnetic indices data and 1270 SSC (storm sudden commencement) events from the year 1968 to 2010 by defining the R-M effect with positive/negative IMF polarity (IMF away/toward the Sun). The results obtained in this study have shown that the response of geomagnetic activity to the R-M effect with positive/negative IMF polarity are rather profound: the geomagnetic activity is much more intense around fall equinox when the direction of IMF is away the Sun, while much more intense around spring equinox when the direction of IMF is toward the Sun. The seasonal and diurnal variation of geomagnetic activity after SSCs can be attributed to both R-M effect and the equinoctial hypothesis; the R-M effect explains most part of variance of southward IMF, while the equinoctial hypothesis explains similar variance of ring current injection and geomagnetic indices as the R-M effect. However, the R-M effect with positive/negative IMF polarity explains the difference between SSCs with positive/negative IMF By accurately, while the equinoctial hypothesis cannot explain such difference at the spring and fall equinoxes. Thus, the R-M effect with positive/negative IMF polarity is more reasonable to explain seasonal and diurnal variation of geomagnetic activity under extreme solar wind conditions.

  3. Wheel running improves REM sleep and attenuates stress-induced flattening of diurnal rhythms in F344 rats.

    PubMed

    Thompson, Robert S; Roller, Rachel; Greenwood, Benjamin N; Fleshner, Monika

    2016-05-01

    Regular physical activity produces resistance to the negative health consequences of stressor exposure. One way that exercise may confer stress resistance is by reducing the impact of stress on diurnal rhythms and sleep; disruptions of which contribute to stress-related disease including mood disorders. Given the link between diurnal rhythm disruptions and stress-related disorders and that exercise both promotes stress resistance and is a powerful non-photic biological entrainment cue, we tested if wheel running could reduce stress-induced disruptions of sleep/wake behavior and diurnal rhythms. Adult, male F344 rats with or without access to running wheels were instrumented for biotelemetric recording of diurnal rhythms of locomotor activity, heart rate, core body temperature (CBT), and sleep (i.e. REM, NREM, and WAKE) in the presence of a 12 h light/dark cycle. Following 6 weeks of sedentary or exercise conditions, rats were exposed to an acute stressor known to disrupt diurnal rhythms and produce behaviors associated with mood disorders. Prior to stressor exposure, exercise rats had higher CBT, more locomotor activity during the dark cycle, and greater %REM during the light cycle relative to sedentary rats. NREM and REM sleep were consolidated immediately following peak running to a greater extent in exercise, compared to sedentary rats. In response to stressor exposure, exercise rats expressed higher stress-induced hyperthermia than sedentary rats. Stressor exposure disrupted diurnal rhythms in sedentary rats; and wheel running reduced these effects. Improvements in sleep and reduced diurnal rhythm disruptions following stress could contribute to the health promoting and stress protective effects of exercise. PMID:27124542

  4. Meridional Flow Variations in Cycles 23 and 24: Active Latitude Control of Sunspot Cycle Amplitudes

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Upton, Lisa

    2013-01-01

    We have measured the meridional motions of magnetic elements observed in the photosphere over sunspot cycles 23 and 24 using magnetograms from SOHO/MDI and SDO/HMI. Our measurements confirm the finding of Komm, Howard, and Harvey (1993) that the poleward meridional flow weakens at cycle maxima. Our high spatial and temporal resolution analyses show that this variation is in the form of a superimposed inflow toward the active latitudes. This inflow is weaker in cycle 24 when compared to the inflow in 23, the stronger cycle. This systematic modulation of the meridional flow can modulate the amplitude of the following sunspot cycle through its influence on the Sun's polar fields.

  5. Diurnal Lightning Distributions as Observed by the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS)

    NASA Technical Reports Server (NTRS)

    Bailey, Jeff C.; Blakeslee, Richard J.; Buechler, Dennis E.; Christian, Hugh J.

    2007-01-01

    Data obtained from the Optical Transient Detector (April 1995 to March 2000) and the Lightning Imaging Sensor (December 1997 to December 2005) satellites (70 and 35 inclination low earth orbits, respectively) are used to statistically determine the number of flashes in the annual and seasonal diurnal cycle as a function of local and universal time. The data are further subdivided by season, land versus ocean, northern versus southern hemisphere, and other spatial (e.g., continents) and temporal (e.g., time of peak diurnal amplitude) categories. The data include corrections for detection efficiency and instrument view time. Continental results display strong diurnal variation, with a lightning peak in the late afternoon and a minimum in late morning. In regions of the world dominated by large mesoscale convective systems the peak in the diurnal curve shifts toward late evening or early morning hours. The maximum diurnal flash rate occurs in June-August, corresponding to the Northern Hemisphere summer, while the minimum occurs in December-February. Summer lightning dominates over winter activity and springtime lightning dominates over autumn activity at most continental locations. This latter behavior occurs especially strongly over the Amazon region in South America in September-November. Oceanic lightning activity in winter and autumn tends to exceed that in summer and spring. Global lightning is well correlated in phase but not in amplitude with the Carnegie curve. The diurnal flash rate varies about 4-35 percent about the mean, while the Carnegie curve varies around 4-15 percent.

  6. Rest-Activity Cycles in Childhood and Adolescent Depression.

    ERIC Educational Resources Information Center

    Armitage, Roseanne; Hoffmann, Robert; Emslie, Graham; Rintelman, Jeanne; Moore, Jarrette; Lewis, Kelly

    2004-01-01

    Objective: To quantify circadian rhythms in rest-activity cycles in depressed children and adolescents. Method: Restactivity cycles were evaluated by actigraphy over five consecutive 24-hour periods in 100 children and adolescents, including 59 outpatients with major depressive disorder (MDD) and 41 healthy normal controls. Total activity, total…

  7. Geomagnetic Activity Indicates Large Amplitude for Sunspot Cycle 24

    NASA Technical Reports Server (NTRS)

    Hathaway, D. H.; Wilson, R. M.

    2006-01-01

    The level of geomagnetic activity near the time of solar activity minimum has been shown to be a reliable indicator for the amplitude of the following solar activity maximum. The geomagnetic activity index aa can be split into two components: one associated with solar flares, prominence eruptions, and coronal mass ejections which follows the solar activity cycle and a second component associated with recurrent high speed solar wind streams which is out of phase with the solar activity cycle. This second component often peaks before solar activity minimum and has been one of the most reliable indicators for the amplitude of the following maximum. The size of the recent maximum in this second component indicates that solar activity cycle 24 will be much higher than average - similar in size to cycles 21 and 22.

  8. Inferences on Stellar Activity and Stellar Cycles from Asteroseismology

    NASA Astrophysics Data System (ADS)

    Chaplin, William J.; Basu, Sarbani

    2014-12-01

    The solar activity cycle can be studied using many different types of observations, such as counting sunspots, measuring emission in the Ca II H&K lines, magnetograms, radio emissions, etc. One of the more recent ways of studying solar activity is to use the changing properties of solar oscillations. Stellar activity cycles are generally studied using the Ca II lines, or sometimes using photometry. Asteroseismology is potentially an exciting means of studying these cycles. In this article we examine whether or not asteroseismic data can be used for this purpose, and what the asteroseismic signatures of stellar activity are. We also examine how asteroseismology may help in more indirect ways.

  9. Transcriptomic and proteomic dynamics in the metabolism of a diazotrophic cyanobacterium, Cyanothece sp. PCC 7822 during a diurnal light–dark cycle

    SciTech Connect

    Welkie, David; Zhang, Xiaohui; Markillie, Meng; Taylor, Ronald; Orr, Galya; Jacobs, Jon; Bhide, Ketaki; Thimmapuram, Jyothi; Gritsenko, Marina; Mitchell, Hugh; Smith, Richard D; Sherman, Louis A

    2014-12-29

    Cyanothece sp. PCC 7822 is an excellent cyanobacterial model organism with great potential to be applied as a biocatalyst for the production of high value compounds. Like other unicellular diazotrophic cyanobacterial species, it has a tightly regulated metabolism synchronized to the light-dark cycle. Utilizing transcriptomic and proteomic methods, we were able to quantify the relationships between transcription and translation underlying central and secondary metabolism in response to nitrogen free, 12 hour light and 12 hour dark conditions.

  10. Forecasting the Peak of the Present Solar Activity Cycle

    NASA Astrophysics Data System (ADS)

    Hamid, Rabab; Marzouk, Beshir

    2016-07-01

    Solar forecasting of the level of sun Activity is very important subject for all space programs. Most predictions are based on the physical conditions prevailing at or before the solar cycle minimum preceding the maximum in question. Our aim is to predict the maximum peak of cycle 24 using precursor techniques in particular those using spotless event, geomagnetic aa min. index and solar flux F10.7. Also prediction of exact date of the maximum (Tr) is taken in consideration. A study of variation over previous spotless event for cycles 7-23 and that for even cycles (8-22) are carried out for the prediction. Linear correlation between RM and spotless event around the preceding minimum gives RM24t = 101.9with rise time Tr = 4.5 Y. For the even cycles RM24e = 108.3 with rise time Tr = 3.9 Y. Based on the average aa min. index for the year of sunspot minimum cycles (13 - 23), we estimate the expected amplitude for cycle 24 to be RMaa = 116.5 for both the total and even cycles. Application of the data of solar flux F10.7 which cover only cycles (19-23) was taken in consideration and gives predicted maximum amplitude R24 10.7 = 146, which are over estimation. Our result indicating a somewhat weaker cycle 24 as compared to cycles 21-23.

  11. A solar cycle timing predictor - The latitude of active regions

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.

    1990-01-01

    A 'Spoerer butterfly' method is used to examine solar cycle 22. It is shown from the latitude of active regions that the cycle can now be expected to peak near November 1989 + or - 8 months, basically near the latter half of 1989.

  12. The connection between stellar activity cycles and magnetic field topology

    NASA Astrophysics Data System (ADS)

    See, V.; Jardine, M.; Vidotto, A. A.; Donati, J.-F.; Boro Saikia, S.; Bouvier, J.; Fares, R.; Folsom, C. P.; Gregory, S. G.; Hussain, G.; Jeffers, S. V.; Marsden, S. C.; Morin, J.; Moutou, C.; do Nascimento, J. D.; Petit, P.; Waite, I. A.

    2016-08-01

    Zeeman Doppler imaging has successfully mapped the large-scale magnetic fields of stars over a large range of spectral types, rotation periods and ages. When observed over multiple epochs, some stars show polarity reversals in their global magnetic fields. On the Sun, polarity reversals are a feature of its activity cycle. In this paper, we examine the magnetic properties of stars with existing chromospherically determined cycle periods. Previous authors have suggested that cycle periods lie on multiple branches, either in the cycle period-Rossby number plane or the cycle period-rotation period plane. We find some evidence that stars along the active branch show significant average toroidal fields that exhibit large temporal variations while stars exclusively on the inactive branch remain dominantly poloidal throughout their entire cycle. This lends credence to the idea that different shear layers are in operation along each branch. There is also evidence that the short magnetic polarity switches observed on some stars are characteristic of the inactive branch while the longer chromospherically determined periods are characteristic of the active branch. This may explain the discrepancy between the magnetic and chromospheric cycle periods found on some stars. These results represent a first attempt at linking global magnetic field properties obtained form ZDI and activity cycles.

  13. Influenza pandemics, solar activity cycles, and vitamin D.

    PubMed

    Hayes, Daniel P

    2010-05-01

    There is historic evidence that influenza pandemics are associated with solar activity cycles (the Schwabe-cycle of about 11-years periodicity). The hypothesis is presented and developed that influenza pandemics are associated with solar control of vitamin D levels in humans which waxes and wanes in concert with solar cycle dependent ultraviolet radiation. It is proposed that this solar cycle dependence arises both directly from cyclic control of the amount of ultraviolet radiation as well as indirectly through cyclic control of atmospheric circulation and dynamics. PMID:20056531

  14. Diurnally entrained anticipatory behavior in archaea.

    PubMed

    Whitehead, Kenia; Pan, Min; Masumura, Ken-ichi; Bonneau, Richard; Baliga, Nitin S

    2009-01-01

    By sensing changes in one or few environmental factors biological systems can anticipate future changes in multiple factors over a wide range of time scales (daily to seasonal). This anticipatory behavior is important to the fitness of diverse species, and in context of the diurnal cycle it is overall typical of eukaryotes and some photoautotrophic bacteria but is yet to be observed in archaea. Here, we report the first observation of light-dark (LD)-entrained diurnal oscillatory transcription in up to 12% of all genes of a halophilic archaeon Halobacterium salinarum NRC-1. Significantly, the diurnally entrained transcription was observed under constant darkness after removal of the LD stimulus (free-running rhythms). The memory of diurnal entrainment was also associated with the synchronization of oxic and anoxic physiologies to the LD cycle. Our results suggest that under nutrient limited conditions halophilic archaea take advantage of the causal influence of sunlight (via temperature) on O(2) diffusivity in a closed hypersaline environment to streamline their physiology and operate oxically during nighttime and anoxically during daytime. PMID:19424498

  15. Butterfly Diagram and Activity Cycles in HR 1099

    NASA Astrophysics Data System (ADS)

    Berdyugina, Svetlana V.; Henry, Gregory W.

    2007-04-01

    We analyze photometric data of the active RS CVn-type star HR 1099 for the years 1975-2006 with an inversion technique and reveal the nature of two activity cycles of 15-16 yr and 5.3+/-0.1 yr duration. The 16 yr cycle is related to variations of the total spot area and is coupled with the differential rotation, while the 5.3 yr cycle is caused by the symmetric redistribution of the spotted area between the opposite stellar hemispheres (flip-flop cycle). We recover long-lived active regions comprising two active longitudes that migrate in the orbital reference frame with a variable rate because of the differential rotation along with changes in the mean spot latitudes. The migration pattern is periodic with the 16 yr cycle. Combining the longitudinal migration of the active regions with a previously measured differential rotation law, we recover the first stellar butterfly diagram without an assumption about spot shapes. We find that mean latitudes of active regions at opposite longitudes change antisymmetrically in the course of the 16 yr cycle: while one active region migrates to the pole, the other approaches the equator. This suggests a precession of the global magnetic field with respect to the stellar rotational axis.

  16. Diurnal variations of Titan

    NASA Astrophysics Data System (ADS)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Mueller-Wodarg, I. C. F.; Kasprzak, W. T.; Waite, J. H.

    2009-04-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1,000 and 1,400 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from 8 close encounters of the Cassini spacecraft with Titan. Though there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ~700 cm-3 below ~1,300 km. Such a plateau is associated with the combination of distinct diurnal variations of light and heavy ions. Light ions (e.g. CH5+, HCNH+, C2H5+) show strong diurnal variation, with clear bite-outs in their nightside distributions. In contrast, heavy ions (e.g. c-C3H3+, C2H3CNH+, C6H7+) present modest diurnal variation, with significant densities observed on the nightside. We propose that the distinctions between light and heavy ions are associated with their different chemical loss pathways, with the former primarily through "fast" ion-neutral chemistry and the latter through "slow" electron dissociative recombination. The INMS data suggest day-to-night transport as an important source of ions on Titan's nightside, to be distinguished from the conventional scenario of auroral ionization by magnetospheric particles as the only ionizing source on the nightside. This is supported by the strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes. We construct a time-dependent ion chemistry model to investigate the effects of day-to-night transport on the ionospheric structures of Titan. The predicted diurnal variation has similar general characteristics to those observed, with some apparent discrepancies which could be reconciled by imposing fast horizontal thermal winds in Titan's upper atmosphere.

  17. Meridional Flow Variations in Cycles 23 and 24: Active Latitude Control of Sunspot Cycle Amplitudes

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Upton, Lisa

    2013-01-01

    We have measured the meridional motions of magnetic elements observed in the photosphere over sunspot cycles 23 and 24 using magnetograms from SOHO/MDI and SDO/HMI. Our measurements confirm the finding of Komm, Howard, and Harvey (1993) that the poleward meridional flow weakens at cycle maxima. Our high spatial and temporal resolution analyses show that this variation is in the form of a superimposed inflow toward the active latitudes. This inflow is weaker in cycle 24 when compared to the inflow in 23, the stronger cycle. This systematic modulation of the meridional flow should also modulate the amplitude of the following sunspot cycle through its influence on the Sun's polar fields. The observational evidence and the theoretical consequences (similar to those of Cameron and Schussler (2012)) will be described.

  18. Meridional Flow Variations in Cycles 23 and 24: Active Latitude Control of Sunspot Cycle Amplitudes

    NASA Astrophysics Data System (ADS)

    Hathaway, David H.; Upton, L.

    2013-07-01

    We have measured the meridional motions of magnetic elements observed in the photosphere over sunspot cycles 23 and 24 using magnetograms from SOHO/MDI and SDO/HMI. Our measurements confirm the finding of Komm, Howard, and Harvey (1993) that the poleward meridional flow weakens at cycle maxima. Our high spatial and temporal resolution analyses show that this variation is in the form of a superimposed inflow toward the active latitudes. This inflow is weaker in cycle 24 when compared to the inflow in 23, the stronger cycle. This systematic modulation of the meridional flow should also modulate the amplitude of the following sunspot cycle through its influence on the Sun’s polar fields. The observational evidence and the theoretical consequences (similar to those of Cameron and Schussler (2012)) will be described. Komm, Howard, and Harvey (1993) Solar Phys. 147, 207. Cameron and Schussler (2012) Astron. Astrophys. 548, A57.

  19. Differential arousal regulation by prokineticin 2 signaling in the nocturnal mouse and the diurnal monkey.

    PubMed

    Zhou, Qun-Yong; Burton, Katherine J; Neal, Matthew L; Qiao, Yu; Kanthasamy, Anumantha G; Sun, Yanjun; Xu, Xiangmin; Ma, Yuanye; Li, Xiaohan

    2016-01-01

    The temporal organization of activity/rest or sleep/wake rhythms for mammals is regulated by the interaction of light/dark cycle and circadian clocks. The neural and molecular mechanisms that confine the active phase to either day or night period for the diurnal and the nocturnal mammals are unclear. Here we report that prokineticin 2, previously shown as a circadian clock output molecule, is expressed in the intrinsically photosensitive retinal ganglion cells, and the expression of prokineticin 2 in the intrinsically photosensitive retinal ganglion cells is oscillatory in a clock-dependent manner. We further show that the prokineticin 2 signaling is required for the activity and arousal suppression by light in the mouse. Between the nocturnal mouse and the diurnal monkey, a signaling receptor for prokineticin 2 is differentially expressed in the retinorecipient suprachiasmatic nucleus and the superior colliculus, brain projection targets of the intrinsically photosensitive retinal ganglion cells. Blockade with a selective antagonist reveals the respectively inhibitory and stimulatory effect of prokineticin 2 signaling on the arousal levels for the nocturnal mouse and the diurnal monkey. Thus, the mammalian diurnality or nocturnality is likely determined by the differential signaling of prokineticin 2 from the intrinsically photosensitive retinal ganglion cells onto their retinorecipient brain targets. PMID:27535380

  20. Diurnal activity rhythms of the subterranean termite Anacanthotermes vagans (Hagen) under laboratory and field conditions of the Kuwait desert

    NASA Astrophysics Data System (ADS)

    Absuhama, Faysal T.; Al Houty, Wasmia A.

    1989-03-01

    Daily foraging activity of Anacanthotermes vagans was tested using toilet paper rolls as bait. The highest activity was recorded at midnight and during the hours of the early morning in both summer and winter seasons. In spring the time of highest activity was reversed to take place at midday, afternoon and early evening. Aktograph records in the laboratory demonstrated that individual workers are active most of the day and not naturally entrianed by photoperiods. Daily activity of groups of 10 workers was not statistically different from that of individual workers.

  1. Men and women differ in their diurnal expression of monocyte peroxisome proliferator-activated receptor-α in the fed but not in the fasted state.

    PubMed

    Wege, Nicole; Schutkowski, Alexandra; Boenn, Markus; Bialek, Joanna; Schlitt, Axel; Noack, Frank; Grosse, Ivo; Stangl, Gabriele I

    2015-07-01

    Peroxisome proliferator-activated receptor-α (PPARα) plays a pivotal role in regulating metabolic response to fasting and is an inhibitor of inflammatory pathways in immune cells. It represents a therapeutic target for treatment of several diseases, mainly hyperlipidemia. To shed light on PPARα expression changes in response to fasting, young healthy male and female volunteers were fed or fasted for 24 hours. Monocytes were analyzed every 2 hours to compile both profiles of mRNA and protein expression of PPARα and its interactive partner, the circadian pacemaker brain and muscle aryl hydrocarbon receptor nuclear translocator like-1 (BMAL1). We found that women change their diurnal expression profiles of PPARα and BMAL1 when switching from the fed to the fasted state, whereas men do not. Interestingly, the PPARα and BMAL1 profiles of men and women in the fed state are different, whereas the profiles in the fasted state are virtually identical. The finding of diametrically opposite responses of male and female PPARα expression in the fed state might have practical implication in human medicine as PPARα activators like fibrates are used for the therapy of chronic lymphocytic leukemia, microvascular complications in diabetes, and kidney diseases. PMID:25825462

  2. An initial estimate of the global distribution of diurnal variation in sea surface salinity

    NASA Astrophysics Data System (ADS)

    Fine, E. C.; Bryan, F. O.; Large, W. G.; Bailey, D. A.

    2015-05-01

    Diurnal variations in sea surface salinity (SSS) have been observed at a few selected locations with adequate in situ instrumentation. Such variations result primarily from imbalances between surface freshwater fluxes and vertical mixing of deeper water to the surface. New observations becoming available from satellite salinity remote sensing missions could help to constrain estimates of diurnal variations in air-sea exchange of freshwater, and provide insight into the processes governing diurnal variability of mixing processes in the upper ocean. Additionally, a better understanding of variation in near surface salinity is required to compare satellite measured SSS with in situ measurements at a few meters depth. The diurnal SSS variations should be reflected as differences between ascending and descending pass retrievals from the Aquarius and SMOS satellites; however, the diurnal signal can be masked by inadequacies of the geophysical corrections used in processing the satellite measurements. In this study, we quantify the expected range of diurnal SSS variations using a model developed for predicting diurnal sea surface temperature variations. We present estimates for the mean and variance of the global diurnal SSS cycle, contrasting it with the diurnal cycle of sea surface temperature. We find the SSS diurnal cycle can be significant throughout the tropics, with mean amplitudes of up to 0.1 psu in areas with heavy precipitation. Predicted maximum diurnal ranges approach 2 psu in select regions. Surface freshening in Aquarius salinity retrievals is shown to be larger for ascending than descending passes, consistent with the expectations from the model simulation.

  3. Geothermal activity helps life survive glacial cycles.

    PubMed

    Fraser, Ceridwen I; Terauds, Aleks; Smellie, John; Convey, Peter; Chown, Steven L

    2014-04-15

    Climate change has played a critical role in the evolution and structure of Earth's biodiversity. Geothermal activity, which can maintain ice-free terrain in glaciated regions, provides a tantalizing solution to the question of how diverse life can survive glaciations. No comprehensive assessment of this "geothermal glacial refugia" hypothesis has yet been undertaken, but Antarctica provides a unique setting for doing so. The continent has experienced repeated glaciations that most models indicate blanketed the continent in ice, yet many Antarctic species appear to have evolved in almost total isolation for millions of years, and hence must have persisted in situ throughout. How could terrestrial species have survived extreme glaciation events on the continent? Under a hypothesis of geothermal glacial refugia and subsequent recolonization of nongeothermal regions, we would expect to find greater contemporary diversity close to geothermal sites than in nongeothermal regions, and significant nestedness by distance of this diversity. We used spatial modeling approaches and the most comprehensive, validated terrestrial biodiversity dataset yet created for Antarctica to assess spatial patterns of diversity on the continent. Models clearly support our hypothesis, indicating that geothermally active regions have played a key role in structuring biodiversity patterns in Antarctica. These results provide critical insights into the evolutionary importance of geothermal refugia and the history of Antarctic species. PMID:24616489

  4. Geothermal activity helps life survive glacial cycles

    PubMed Central

    Fraser, Ceridwen I.; Terauds, Aleks; Smellie, John; Convey, Peter; Chown, Steven L.

    2014-01-01

    Climate change has played a critical role in the evolution and structure of Earth’s biodiversity. Geothermal activity, which can maintain ice-free terrain in glaciated regions, provides a tantalizing solution to the question of how diverse life can survive glaciations. No comprehensive assessment of this “geothermal glacial refugia” hypothesis has yet been undertaken, but Antarctica provides a unique setting for doing so. The continent has experienced repeated glaciations that most models indicate blanketed the continent in ice, yet many Antarctic species appear to have evolved in almost total isolation for millions of years, and hence must have persisted in situ throughout. How could terrestrial species have survived extreme glaciation events on the continent? Under a hypothesis of geothermal glacial refugia and subsequent recolonization of nongeothermal regions, we would expect to find greater contemporary diversity close to geothermal sites than in nongeothermal regions, and significant nestedness by distance of this diversity. We used spatial modeling approaches and the most comprehensive, validated terrestrial biodiversity dataset yet created for Antarctica to assess spatial patterns of diversity on the continent. Models clearly support our hypothesis, indicating that geothermally active regions have played a key role in structuring biodiversity patterns in Antarctica. These results provide critical insights into the evolutionary importance of geothermal refugia and the history of Antarctic species. PMID:24616489

  5. Nocturnal activity by diurnal lizards (Sceloporus jarrovi, S. virgatus) eaten by small owls (Glaucidium gnoma, Otus trichopsis)

    USGS Publications Warehouse

    Duncan, W.W.; Gehlbach, F.R.; Middendorf, G. A., III

    2003-01-01

    Whiskered screech-owls (Otus trichopsis) and northern pygmy-owls (Glaucidium gnoma) delivered freshly caught Yarrow's spiny lizards (Sceloporus jarrovi) and striped plateau lizards (S. virgatus) to nestlings from dusk to dark in southeastern Arizona. This observation stimulated studies of the prey deliveries by the owls and lizard activity patterns, because the lizards are not known to be nocturnal. Lizards were more frequent prey of both owls than endothermic vertebrates but infrequent compared to arthropods, a pattern in the pygmy-owl that differs from its northern populations. Yarrow's spiny lizard, the most abundant and frequently captured lizard, was most active in the morning but also active in the evening. Striped plateau lizard, the second most abundant and depredated species, had morning and evening peaks of activity. Few lizards, including S. clarki and Urosaurus ornatus, but not Cnemidophorus exsanguis and C. sonorae, were active at or after dark, when relatively few were captured by the owls.

  6. A quest for activity cycles in low-mass stars

    NASA Astrophysics Data System (ADS)

    Vida, K.; Kriskovics, L.; Oláh, K.

    2013-11-01

    Long-term photometric measurements in a sample of ultrashort-period (P≈0.5 days or less) single and binary stars of different interior structures are analysed. A loose correlation exists between the rotational rate and cycle lengths of active stars, regardless of their evolutionary state and the corresponding physical parameters. The shortest cycles are expected for the fastest rotators of the order of 1-2 years, which is reported in this paper.

  7. Radio Imaging Observations of Solar Activity Cycle and Its Anomaly

    NASA Astrophysics Data System (ADS)

    Shibasaki, K.

    2011-12-01

    The 24th solar activity cycle has started and relative sunspot numbers are increasing. However, their rate of increase is rather slow compared to previous cycles. Active region sizes are small, lifetime is short, and big (X-class) flares are rare so far. We study this anomalous situation using data from Nobeyama Radioheliograph (NoRH). Radio imaging observations have been done by NoRH since 1992. Nearly 20 years of daily radio images of the Sun at 17 GHz are used to synthesize a radio butterfly diagram. Due to stable operation of the instrument and a robust calibration method, uniform datasets are available covering the whole period of observation. The radio butterfly diagram shows bright features corresponding to active region belts and their migration toward low latitude as the solar cycle progresses. In the present solar activity cycle (24), increase of radio brightness is delayed and slow. There are also bright features around both poles (polar brightening). Their brightness show solar cycle dependence but peaks around solar minimum. Comparison between the last minimum and the previous one shows decrease of its brightness. This corresponds to weakening of polar magnetic field activity between them. In the northern pole, polar brightening is already weakened in 2011, which means it is close to solar maximum in the northern hemisphere. Southern pole does not show such feature yet. Slow rise of activity in active region belt, weakening of polar activity during the minimum, and large north-south asymmetry in polar activity imply that global solar activity and its synchronization are weakening.

  8. Forecast for solar cycle 23 activity: a progress report

    NASA Astrophysics Data System (ADS)

    Ahluwalia, H. S.

    2001-08-01

    At the 25th International Cosmic Ray Conference (ICRC) at Durban, South Africa, I announced the discovery of a three cycle quasi-periodicity in the ion chamber data string assembled by me, for the 1937 to 1994 period (Conf. Pap., v. 2, p. 109, 1997). It corresponded in time with a similar quasi-periodicity observed in the dataset for the planetary index Ap. At the 26th ICRC at Salt Lake City, UT, I reported on our analysis of the Ap data to forecast the amplitude of solar cycle 23 activity (Conf. Pap., v. 2, pl. 260, 1999). I predicted that cycle 23 will be moderate (a la cycle 17), notwithstanding the early exuberant forecasts of some solar astronomers that cycle 23, "may be one of the greatest cycles in recent times, if not the greatest." Sunspot number data up to April 2001 indicate that our forecast appears to be right on the mark. We review the solar, interplanetary and geophysical data and describe the important lessons learned from this experience. 1. Introduction Ohl (1971) was the first to realize that Sun may be sending us a subliminal message as to its intent for its activity (Sunspot Numbers, SSN) in the next cycle. He posited that the message was embedded in the geomagnetic activity (given by sum Kp). Schatten at al (1978) suggested that Ohl hypothesis could be understood on the basis of the model proposed by Babcock (1961) who suggested that the high latitude solar poloidal fields, near a minimum, emerge as the toroidal fields on opposite sides of the solar equator. This is known as the Solar Dynamo Model. One can speculate that the precursor poloidal solar field is entrained in the high speed solar wind streams (HSSWS) from the coronal holes which are observed at Earth's orbit during the descending phase of the previous cycle. The interaction

  9. Modeling the rate of turnover of DOC and particulate organic carbon in a UK, peat-hosted stream: Including diurnal cycling in short-residence time systems

    NASA Astrophysics Data System (ADS)

    Worrall, F.; Moody, C. S.

    2014-10-01

    This study proposes a multicomponent, multiprocess scheme to explain the turnover of organic matter (particulate and dissolved organic matter) in streams. The scheme allows for production and degradation of organic matter by both photic and aphotic processes with transformation of dissolved organic carbon (DOC) to increasingly refractory forms. The proposed scheme was compared to 10 months of experimental observations of the turnover and fate of particulate and dissolved organic matter in stream water from a peat-covered catchment. The scheme was able to explain average decline in DOC concentration of 65% over 70 h with a 13% mean average percentage error based on turnover in three types of organic matter (particulate, labile dissolved, and refractory dissolved) although the order and rate of reactions did change between sets of experimental observations. The modeling suggests that activation energies are low for all except the most refractory forms of DOC in turn, suggesting that processes are not sensitive to temperature change. Application of the modeling scheme to organic matter turnover in the River Tees, northern England, showed that annual removal of total organic carbon was equivalent to between 13 and 33 t C/km2/yr from an at source export of between 22 and 56 t C/km2/yr giving a total in-stream loss rate of between 53 and 62% over a median in-stream residence time of 35 h.

  10. Cycle Length Dependence of Stellar Magnetic Activity and Solar Cycle 23

    NASA Astrophysics Data System (ADS)

    Choi, Hwajin; Lee, Jeongwoo; Oh, Suyeon; Kim, Bogyeong; Kim, Hoonkyu; Yi, Yu

    2015-03-01

    Solar cycle (SC) 23 was extraordinarily long with remarkably low magnetic activity. We have investigated whether this is a common behavior of solar-type stars. From the Ca ii H and K line intensities of 111 stars observed at Mount Wilson Observatory from 1966 to 1991, we have retrieved data of all 23 G-type stars and recalculated their cycle lengths using the damped least-squares method for the chromospheric activity index S as a function of time. A regression analysis was performed to find relations between the derived cycle length, Pavg, and the index for excess chromospheric emission, RHK\\prime . As a noteworthy result, we found a segregation between young and old solar-type stars in the cycle length-activity correlation. We incorporated the relation for the solar-type stars into the previously known rule for stellar chromospheric activity and brightness to estimate the variation of solar brightness from SC 22 to SC 23 as (0.12 ± 0.06)%, much higher than the actual variation of total solar irradiance (TSI) ≤0.02%. We have then examined solar spectral irradiance (SSI) to find a good phase correlation with a sunspot number in the wavelength range of 170-260 nm, which is close to the spectral range effective in heating the Earth’s atmosphere. Therefore, it appears that SSI rather than TSI is a good indicator of the chromospheric activity, and its cycle length dependent variation would be more relevant to the possible role of the Sun in the cyclic variation of the Earth’s atmosphere.

  11. Variation of Meteor Heights and Solar-Cycle Activity

    NASA Astrophysics Data System (ADS)

    Porubcan, Vladimír; Bucek, Marek; Cevolani, Giordano; Zigo, Pavel

    2012-08-01

    Photographic meteor observations of the Perseid meteoroid stream compiled from the IAU Meteor Data Center catalogue are analyzed from the viewpoint of possible long-term variation of meteor heights with the solar-cycle activity, which was previously reported from radio observations. The observed beginning and end-point heights of the Perseids, normalized for the geocentric velocity and the absolute photographic magnitude, do not show a variation consistent with the solar-cycle activity. This result is valid for the mass range of larger meteoroids observed by photographic techniques, and must be still verified also for the range of smaller meteoroids observed by TV and radio methods.

  12. Memory performance is related to the cortisol awakening response in older people, but not to the diurnal cortisol slope.

    PubMed

    Hidalgo, Vanesa; Almela, Mercedes; Pulopulos, Matias M; Salvador, Alicia

    2016-09-01

    There are large individual differences in age-related cognitive decline. Hypothalamic-pituitary-adrenal axis (HPA-axis) functioning has been suggested as one of the mechanisms underlying these differences. This study aimed to investigate the relationships between the diurnal cortisol cycle, measured as the cortisol awakening response (CAR), and the diurnal cortisol slope (DCS) and the memory performance of healthy older people. To do so, we assessed the verbal, visual, and working memory performance of 64 participants (32 men) from 57 to 76 years old who also provided 14 saliva samples on two consecutive weekdays to determine their diurnal cortisol cycle. The CAR was linearly and negatively associated with verbal (significantly) and visual (marginally) memory domains, but not with working memory. Sex did not moderate these relationships. Furthermore, no associations were found between the DCS and any of the three memory domains assessed. Our results indicate that the two components of the diurnal cortisol cycle have different relationships with memory performance, with the CAR being more relevant than DCS in understanding the link from HPA-axis activity and regulation to different types of memory. These results suggest that the CAR is related to memory domains dependent on hippocampal functioning (i.e., declarative memory), but not to those that are more dependent on prefrontal cortex functioning (i.e., working memory). PMID:27266967

  13. MAGNETIC ACTIVITY CYCLES IN THE EXOPLANET HOST STAR {epsilon} ERIDANI

    SciTech Connect

    Metcalfe, T. S.; Mathur, S.; Buccino, A. P.; Mauas, P. J. D.; Petrucci, R.; Brown, B. P.; Soderblom, D. R.; Henry, T. J.; Hall, J. C.; Basu, S.

    2013-02-01

    The active K2 dwarf {epsilon} Eri has been extensively characterized both as a young solar analog and more recently as an exoplanet host star. As one of the nearest and brightest stars in the sky, it provides an unparalleled opportunity to constrain stellar dynamo theory beyond the Sun. We confirm and document the 3-year magnetic activity cycle in {epsilon} Eri originally reported by Hatzes and coworkers, and we examine the archival data from previous observations spanning 45 years. The data show coexisting 3-year and 13-year periods leading into a broad activity minimum that resembles a Maunder minimum-like state, followed by the resurgence of a coherent 3-year cycle. The nearly continuous activity record suggests the simultaneous operation of two stellar dynamos with cycle periods of 2.95 {+-} 0.03 years and 12.7 {+-} 0.3 years, which, by analogy with the solar case, suggests a revised identification of the dynamo mechanisms that are responsible for the so-called 'active' and 'inactive' sequences as proposed by Boehm-Vitense. Finally, based on the observed properties of {epsilon} Eri, we argue that the rotational history of the Sun is what makes it an outlier in the context of magnetic cycles observed in other stars (as also suggested by its Li depletion), and that a Jovian-mass companion cannot be the universal explanation for the solar peculiarities.

  14. Diurnal oscillation of SBE expression in sorghum endosperm

    SciTech Connect

    Sun, Chuanxin; Mutisya, J.; Rosenquist, S.; Baguma, Y.; Jansson, C.

    2009-01-15

    Spatial and temporal expression patterns of the sorghum SBEI, SBEIIA and SBEIIB genes, encoding, respectively, starch branching enzyme (SBE) I, IIA and IIB, in the developing endosperm of sorghum (Sorghum bicolor) were studied. Full-length genomic and cDNA clones for sorghum was cloned and the SBEIIA cDNA was used together with gene-specific probes for sorghum SBEIIB and SBEI. In contrast to sorghum SBEIIB, which was expressed primarily in endosperm and embryo, SBEIIA was expressed also in vegetative tissues. All three genes shared a similar temporal expression profile during endosperm development, with a maximum activity at 15-24 days after pollination. This is different from barley and maize where SBEI gene activity showed a significantly later onset compared to that of SBEIIA and SBEIIB. Expression of the three SBE genes in the sorghum endosperm exhibited a diurnal rhythm during a 24-h cycle.

  15. Diurnal variation of the potassium layer in the upper atmosphere

    PubMed Central

    Feng, W.; Höffner, J.; Marsh, D. R.; Chipperfield, M. P.; Dawkins, E. C. M.; Viehl, T. P.

    2015-01-01

    Abstract Measurements of the diurnal cycle of potassium (K) atoms between 80 and 110 km have been made during October (for the years 2004–2011) using a Doppler lidar at Kühlungsborn, Germany (54.1°N, 11.7°E). A pronounced diurnal variation is observed in the K number density, which is explored by using a detailed description of the neutral and ionized chemistry of K in a three‐dimensional chemistry climate model. The model captures both the amplitude and phase of the diurnal and semidiurnal variability of the layer, although the peak diurnal amplitude around 90 km is overestimated. The model shows that the total potassium density (≈ K + K+ + KHCO3) exhibits little diurnal variation at each altitude, and the diurnal variations are largely driven by photochemical conversion between these reservoir species. In contrast, tidally driven vertical transport has a small effect at this midlatitude location, and diurnal fluctuations in temperature are of little significance because they are small and the chemistry of K is relatively temperature independent. PMID:27478284

  16. The Solar Non-activity Cycle of Polar Coronal Holes

    NASA Astrophysics Data System (ADS)

    Kirk, M. S.; Pesnell, W. D.; Young, C. A.

    2015-12-01

    After the unusually extended minimum in 2008 and 2009, solar cycle 24 continues to be an exceptionally weak cycle both in sunspot number and number of large magnetic storms. Coronal holes offer a direct measurement of the non-activity solar cycle, a missing link in our understanding of solar cycle progression. They are prevalent during solar minimum, non-axisymmetric, and are stable. Polar coronal holes are regularly observed capping the northern and southern solar poles in EUV images of the corona and are understood as the primary source of the fast solar wind. We make measurements of these features from 1996 through 2015 using four different NASA imagers: SOHO EIT, STEREO A and B EUVI, and SDO AIA. A measurement of the axial symmetry of the polar holes is seen to have clear solar cycle dependence. Polar coronal holes are aligned with the solar rotation axis during minimum and have a maximum asymmetry between holes of about 14 degrees in the declining phase of the current solar cycle.

  17. Periods of activity cycles in late-type stars

    NASA Technical Reports Server (NTRS)

    Kliorin, N. I.; Ruzmaykin, A. A.; Sokolov, D. D.

    1983-01-01

    The mean magnetic field dynamo theory is utilized to obtain the qualitative dependence of the period of activity on the angular velocity of rotation for stars with sufficiently extensive convective shells. The dependence of the cycle period on the spectral class is also discussed.

  18. A cycling workstation to facilitate physical activity in office settings.

    PubMed

    Elmer, Steven J; Martin, James C

    2014-07-01

    Facilitating physical activity during the workday may help desk-bound workers reduce risks associated with sedentary behavior. We 1) evaluated the efficacy of a cycling workstation to increase energy expenditure while performing a typing task and 2) fabricated a power measurement system to determine the accuracy and reliability of an exercise cycle. Ten individuals performed 10 min trials of sitting while typing (SIT type) and pedaling while typing (PED type). Expired gases were recorded and typing performance was assessed. Metabolic cost during PED type was ∼ 2.5 × greater compared to SIT type (255 ± 14 vs. 100 ± 11 kcal h(-1), P < 0.01). Typing time and number of typing errors did not differ between PED type and SIT type (7.7 ± 1.5 vs. 7.6 ± 1.6 min, P = 0.51, 3.3 ± 4.6 vs. 3.8 ± 2.7 errors, P = 0.80). The exercise cycle overestimated power by 14-138% compared to actual power but actual power was reliable (r = 0.998, P < 0.01). A cycling workstation can facilitate physical activity without compromising typing performance. The exercise cycle's inaccuracy could be misleading to users. PMID:24681071

  19. Activity Cycles in Stars with Highly Active Chromospheres

    NASA Astrophysics Data System (ADS)

    Guinan, Edward F.

    The extended lifetime of the IUE satellite has provided an unique and unanticipated opportunity to examine the long-term evolution of magnetic activity on active chromospheric stars. We propose to obtain further IUE observations of the highly active RS CVn stars V711 Tauri, lambda Andromedae, II Pegasi, and UX Arietis in conjunction with groundbased optical and radio observations, and possibly ROSAT X-ray observations. In addition we would continue IUE observations of the unusual rapidly rotating early G giant, FK Comae, which, although not in the RS CVn category, shares a similarly high level of magnetic activity. These five stars have the most extensive IUE archival coverage for stars of their type and have almost continuous ground-based photometric coverage from about 1975 onward. We aim to trace the long-term development of magnetic activity on these stars: a detailed study of the UV emission-like fluxes will enable us to follow the variations in chromospheric and transition-region activity over an interval of 12-16 years. Optical observations reveal variations in photospheric (starspot) activity: the starspot regions are large (up to 30% of the stellar surface) and vary significantly with time. The main aim of the proposed research is to examine the relationship between chromospheric, transition-region, and photospheric active regions. Elucidation of the role of white-light faculae vis-a-vis spots in effecting stellar irradiance changes is also desirable.

  20. The evolution and orientation of early cycle 22 active regions

    NASA Technical Reports Server (NTRS)

    Cannon, Anne T.; Marquette, William H.

    1991-01-01

    The evolution of six major active regions which appeared during the first phase of the present solar cycle (cycle 22) has been studied. It was found that the northern hemisphere regions exhibited a broad range of evolutionary behavior in which the commonly accepted 'normal pattern' (whereby the follower flux moves preferentially polewards ahead of the leader flux) is represented at one end of the range. At the other end of the range, the leader flux is displaced polewards of the follower flux. In the latter cases equatorward extensions of the polar coronal hole are noted.

  1. The active RS Canum Venaticorum binary II Pegasi. IV. The SPOT activity cycle

    NASA Astrophysics Data System (ADS)

    Berdyugina, S. V.; Berdyugin, A. V.; Ilyin, I.; Tuominen, I.

    1999-10-01

    A total of 6 new surface images of II Peg obtained for the years 1997 and 1998 confirms the recently revealed permanent active longitude structure. The lower limit of the active longitudes' lifetime is now extended up to 25 years. A new ``flip-flop'' phenomenon, redefined as a switch of the activity between the active longitudes, has started in summer of 1998. It coincides reasonably well with the moment predicted from the activity cycle of the star. This confirms definitely the cyclic behaviour of the activity of II Peg we recently discovered. Therefore, we assign numbers to the cycles of 4.65 yr since the earliest photoelectric observations of II Peg and define the active longitudes as ``odd'' and ``even'' corresponding to odd and even numbers of cycles. With such a definition, in late 1998 the 7th cycle began and the ``odd'' active longitude became more active. From the analysis of the spot area evolution within the active longitudes we conclude that the activity cycle is developed as a rearrangement of the nearly constant amount of the spot area between the active longitudes. We discuss the ``flip-flop'' phenomenon as a tracer of stellar activity and the role of the unseen secondary in establishing the cycle. Based on observations collected at the Nordic Optical Telescope (NOT), La Palma, Spain; the 1.25m telescope of the Crimean Astrophysical Observatory, Ukraine; the Phoenix 10 robotic telescope, APT Observatory, Arizona, USA.}

  2. Annual and diurnal african biomass burning temporal dynamics

    NASA Astrophysics Data System (ADS)

    Roberts, G.; Wooster, M. J.; Lagoudakis, E.

    2009-05-01

    Africa is the single largest continental source of biomass burning emissions. Here we conduct the first analysis of one full year of geostationary active fire detections and fire radiative power data recorded over Africa at 15-min temporal interval and a 3 km sub-satellite spatial resolution by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) imaging radiometer onboard the Meteosat-8 satellite. We use these data to provide new insights into the rates and totals of open biomass burning over Africa, particularly into the extremely strong seasonal and diurnal cycles that exist across the continent. We estimate peak daily biomass combustion totals to be 9 and 6 million tonnes of fuel per day in the northern and southern hemispheres respectively, and total fuel consumption between February 2004 and January 2005 is estimated to be at least 855 million tonnes. Analysis is carried out with regard to fire pixel temporal persistence, and we note that the majority of African fires are detected only once in consecutive 15 min imaging slots. An investigation of the variability of the diurnal fire cycle is carried out with respect to 20 different land cover types, and whilst differences are noted between land covers, the fire diurnal cycle characteristics for most land cover type are very similar in both African hemispheres. We compare the Fire Radiative Power (FRP) derived biomass combustion estimates to burned-areas, both at the scale of individual fires and over the entire continent at a 1-degree scale. Fuel consumption estimates are found to be less than 2 kg/m2 for all land cover types noted to be subject to significant fire activity, and for savanna grasslands where literature values are commonly reported the FRP-derived median fuel consumption estimate of 300 g/m2 is well within commonly quoted values. Meteosat-derived FRP data of the type presented here is now available freely to interested users continuously and in near real-time for Africa, Europe and parts

  3. SOLAR ROTATION RATE DURING THE CYCLE 24 MINIMUM IN ACTIVITY

    SciTech Connect

    Antia, H. M.; Basu, Sarbani E-mail: sarbani.basu@yale.ed

    2010-09-01

    The minimum of solar cycle 24 is significantly different from most other minima in terms of its duration as well as its abnormally low levels of activity. Using available helioseismic data that cover epochs from the minimum of cycle 23 to now, we study the differences in the nature of the solar rotation between the minima of cycles 23 and 24. We find that there are significant differences between the rotation rates during the two minima. There are differences in the zonal-flow pattern too. We find that the band of fast rotating region close to the equator bifurcated around 2005 and recombined by 2008. This behavior is different from that during the cycle 23 minimum. By autocorrelating the zonal-flow pattern with a time shift, we find that in terms of solar dynamics, solar cycle 23 lasted for a period of 11.7 years, consistent with the result of Howe et al. (2009). The autocorrelation coefficient also confirms that the zonal-flow pattern penetrates through the convection zone.

  4. Diurnal polar motion

    NASA Technical Reports Server (NTRS)

    Mcclure, P.

    1973-01-01

    An analytical theory is developed to describe diurnal polar motion in the earth which arises as a forced response due to lunisolar torques and tidal deformation. Doodson's expansion of the tide generating potential is used to represent the lunisolar torques. Both the magnitudes and the rates of change of perturbations in the earth's inertia tensor are included in the dynamical equations for the polar motion so as to account for rotational and tidal deformation. It is found that in a deformable earth with Love's number k = 0.29, the angular momentum vector departs by as much as 20 cm from the rotation axis rather than remaining within 1 or 2 cm as it would in a rigid earth. This 20 cm separation is significant in the interpretation of submeter polar motion observations because it necessitates an additional coordinate transformation in order to remove what would otherwise be a 20 cm error source in the conversion between inertial and terrestrial reference systems.

  5. Activity Scratchpad Prototype: Simplifying the Rover Activity Planning Cycle

    NASA Technical Reports Server (NTRS)

    Abramyan, Lucy

    2005-01-01

    The Mars Exploration Rover mission depends on the Science Activity Planner as its primary interface to the Spirit and Opportunity Rovers. Scientists alternate between a series of mouse clicks and keyboard inputs to create a set of instructions for the rovers. To accelerate planning by minimizing mouse usage, a rover planning editor should receive the majority of inputted commands from the keyboard. Thorough investigation of the Eclipse platform's Java editor has provided the understanding of the base model for the Activity Scratchpad. Desirable Eclipse features can be mapped to specific rover planning commands, such as auto-completion for activity titles and content assist for target names. A custom editor imitating the Java editor's features was created with an XML parser for experimenting purposes. The prototype editor minimized effort for redundant tasks and significantly improved the visual representation of XML syntax by highlighting keywords, coloring rules, folding projections, and providing hover assist, templates and an outline view of the code.

  6. Retrieval of the photochemical reflectance index for assessing xanthophyll cycle activity: a comparison of near-surface optical sensors

    NASA Astrophysics Data System (ADS)

    Harris, A.; Gamon, J. A.; Pastorello, G. Z.; Wong, C. Y. S.

    2014-11-01

    Unattended optical sensors are increasingly being deployed on eddy covariance flux towers and are often used to complement existing vegetation and micrometeorological measurements to enable assessment of biophysical states and biogeochemical processes over a range of spatial scales. Of particular interest are sensors that can measure the photochemical reflectance index (PRI), which can provide information pertaining to leaf pigments and photosynthetic activity. This interest has facilitated the production of a new range of lower-cost multispectral sensors specifically designed to measure temporal changes in the PRI signal. However, little is known about the characteristics (spectral, radiometric and temporal) of many of these PRI sensors, making it difficult to compare data obtained from these sensors across time, geographical locations and instruments. Furthermore, direct testing of the capability of these sensors to actually detect the conversion of the xanthophyll cycle, which is the original biological basis of the PRI diurnal signal, is largely absent, often resulting in an unclear interpretation of the signal, particularly given the wide range of factors now known to influence PRI. Through a series of experiments, we assess the sensitivity of one of the leading brands of PRI sensor (Skye SKR 1800) to changes in vegetation photosynthetic activity in response to changing irradiance. We compare the results with those obtained using a more expensive industry-standard visible to near-infrared hyperspectral spectrometer (PP Systems UniSpec) and determine the radiometric compatibility of measurements made by the different instruments. Results suggest that the SKR 1800 instrument is able to track rapid (seconds to minutes) and more gradual diurnal changes in photosynthetic activity associated with xanthophyll cycle pigment conversion. Measurements obtained from both the high and lower cost instrument were significantly linearly correlated but were subject to a large

  7. Patterns of Diurnal Marine Stratocumulus Cloud Fraction Variability

    SciTech Connect

    Burleyson, Casey D.; Yuter, S. E.

    2015-04-01

    The spatial patterns of subtropical marine stratocumulus cloud fraction variability on diurnal time scales are examined using high temporal resolution cloud masks based on 30-min 4 km x 4 km geosynchronous IR data for the period 2003-2010. This data set permits comparison of low cloud fraction variability characteristics among the three marine stratocumulus regions in the southeast Pacific, southeast Atlantic and northeast Pacific. In all three regions, the largest diurnal cycles and earliest time of cloud break up occur on the edges of the cloud field where cloud fractions are in general lower. During the peak season of cloudiness in the southeast Pacific and southeast Atlantic the amplitude of the diurnal cycle on the edges of the cloud deck was greater than 40%, more than double the value found in the center of each cloud deck. The rate at which the cloud breaks up during the day is closely tied to starting cloud fraction at dawn and the shortwave radiative flux. The maximum rate of cloud breakup occurs near 1200 LT. Cloud fraction begins to increase at 1600 LT (before the sun sets) and reaches its maximum value just before dawn. The diurnal cycle characteristics of the southeast Pacific and southeast Atlantic marine stratocumulus cloud decks are more similar to each other than to those in the northeast Pacific. The northeast Pacific cloud deck has weaker diurnal variation, slower rates of cloud breakup during the day for a given cloud fraction at dawn, and higher probabilities for cloud break up overnight.

  8. Oxytocin decreases diurnal and nocturnal arterial blood pressure in the conscious unrestrained spontaneously hypertensive rat.

    PubMed

    Gutkowska, Jolanta; Aliou, Yessoufou; Lavoie, Julie L; Gaab, Katie; Jankowski, Marek; Broderick, Tom L

    2016-06-01

    In this study, we assessed the effects of oxytocin (OT) on mean arterial blood pressure (MAP), heart rate (HR), and locomotor activity (LA) in male spontaneous hypertensive rats (SHR) and Sprague-Dawley (SDR) controls using telemetry. OT was given by intravenous injections of 0.1, 0.2 or 0.4mg/kg to assess short term acute effects or by daily subcutaneous injections of 0.5 or 1.0mg/kg for 5 days. Compared to the saline infusion, (i) intravenous OT, regardless of concentration, increased MAP in SHR and SDR, (ii) HR increased, but was periodically lower in both strains with 0.2 or 0.4mg/kg, and (iii) no effects of OT on LA were observed. Subcutaneous injections demonstrated that (i) 1.0mg/kg for 5days lowered diurnal MAP and HR in SDR and SHR, persisting for 6 days, (ii) 1.0mg/kg decreased nocturnal HR in SDR, (iii) 0.5 and 1.0mg/kg decreased MAP with minor effects on HR in the SHR, and lastly (iv) OT decreased LA mainly during the diurnal cycle in both strains. Our main results show that OT induces significant beneficial effects on cardiovascular function over several diurnal and nocturnal cycles in the SHR, with the most prominent effect being a robust decrease in MAP. PMID:27020751

  9. Global transcriptomic analysis of Cyanothece 51142 reveals robust diurnal oscillation of central metabolic processes

    SciTech Connect

    Stockel, Jana; Welsh, Eric A.; Liberton, Michelle L.; Kunnavakkam, Rangesh V.; Aurora, Rajeev; Pakrasi, Himadri B.

    2008-04-22

    Cyanobacteria are oxygenic photosynthetic organisms, and the only prokaryotes known to have a circadian cycle. Unicellular diazotrophic cyanobacteria such as Cyanothece 51142 can fix atmospheric nitrogen, a process exquisitely sensitive to oxygen. Thus, the intracellular environment of Cyanothece oscillates between aerobic and anaerobic conditions during a day-night cycle. This is accomplished by temporal separation of two processes: photosynthesis during the day, and nitrogen fixation at night. While previous studies have examined periodic changes transcript levels for a limited number of genes in Cyanothece and other unicellular diazotrophic cyanobacteria, a comprehensive study of transcriptional activity in a nitrogen-fixing cyanobacterium is necessary to understand the impact of the temporal separation of photosynthesis and nitrogen fixation on global gene regulation and cellular metabolism. We have examined the expression patterns of nearly 5000 genes in Cyanothece 51142 during two consecutive diurnal periods. We found that ~30% of these genes exhibited robust oscillating expression profiles. Interestingly, this set included genes for almost all central metabolic processes in Cyanothece. A transcriptional network of all genes with significantly oscillating transcript levels revealed that the majority of genes in numerous individual pathways, such as glycolysis, pentose phosphate pathway and glycogen metabolism, were co-regulated and maximally expressed at distinct phases during the diurnal cycle. Our analyses suggest that the demands of nitrogen fixation greatly influence major metabolic activities inside Cyanothece cells and thus drive various cellular activities. These studies provide a comprehensive picture of how a physiologically relevant diurnal light-dark cycle influences the metabolism in a photosynthetic bacterium

  10. Integrated gasification combined-cycle research development and demonstration activities

    SciTech Connect

    Ness, H.M.; Reuther, R.B.

    1995-12-01

    The United States Department of Energy (DOE) has selected six integrated gasification combined-cycle (IGCC) advanced power systems for demonstration in the Clean Coal Technology (CCT) Program. DOE`s Office of Fossil Energy, Morgantown Energy Technology Center, is managing a research development and demonstration (RD&D) program that supports the CCT program, and addresses long-term improvements in support of IGCC technology. This overview briefly describes the CCT projects and the supporting RD&D activities.

  11. Effects of turbulent pumping on stellar activity cycles

    NASA Astrophysics Data System (ADS)

    Do Cao, O.; Brun, A. S.

    2011-12-01

    Stellar magnetic activity of solar like stars is thought to be due to an internal dynamo. While the Sun has been the subject of intense research for refining dynamo models, observations of magnetic cyclic activity in solar type stars have become more and more available, opening a new path to understand the underlying physics behind stellar cycles. For instance, it is key to understand how stellar rotation rate influences magnetic cycle period P_cyc. Recent numerical simulations of advection-dominated Babcock Leighton models have demonstrated that it is difficult to explain this observed trend given a) the strong influence of the cycle period to the meridional circulation amplitude and b) the fact that 3D models indicate that meridional flows become weaker as the rotation rate increases. In this paper, we introduce the turbulent pumping mechanism as another advective process capable also of transporting the magnetic fields. We found that this model is now able to reproduce the observations under the assumption that this effect increases as \\Omega2. The turbulent pumping becomes indeed another major player able to circumvent the meridional circulation. However, for high rotation rates (\\Omega ≃ 5 \\Omega_⊙), its effects dominate those of the meridional circulation, entering a new class of regime dominated by the advection of turbulent pumping and thus leading to a cyclic activity qualitatively different from that of the Sun.

  12. Diversity of Stomoxys spp. (Diptera: Muscidae) and diurnal variations of activity of Stomoxys indicus and S. Calcitrans in a farm, in Wang Nam Khiao District, Nakhon ratchasima Province, Thailand

    PubMed Central

    Keawrayup, S.; Duvallet, G.; Sukonthabhirom, S.; Chareonviriyaphap, T.

    2012-01-01

    A study of species diversity of Stomoxys spp. and diurnal variations of activity of the most abundant was performed during a one year period at a local dairy cattle farm in Wang Nam Khiao District, Nakhon Ratchasima Province, Thailand. Four species of stomoxyine flies were morphologically identified, including Stomoxys indicus Picard 1908, S. calcitrans (Linnaeus 1758), S. sitiens Rondani 1873 and S. uruma Shinonaga and Kanao 1966. The most common species were S. indicus (50.2%) and S. calcitrans (49.5%). S. sitiens and S. uruma were found in small proportions (< 1%). The number of flies captured was significantly different among the three seasons with the greatest number in the rainy season (mean = 66%; df = 2, P < 0.05). The variations of diurnal activity were observed during different period of times (06:00 to 18:00) during three seasons. Both sexes of S. indicus and males of S. calcitrans showed unimodal activity pattern in cool and summer seasons. But a bimodal activity pattern was recorded in rainy season. For females S. calcitrans, a unimodal peak of activity was observed in cool season and a constant variation of activity all along the day in summer and rainy seasons, with an increase from the morning to the evening. A better understanding of stomoxyine fly behavior, especially the daily flight activity, can assist in prioritization and design of appropriate vector prevention and control strategies. PMID:22910668

  13. Diversity of Stomoxys spp. (Diptera: Muscidae) and diurnal variations of activity of Stomoxys indicus and S. calcitrans in a farm, in Wang Nam Khiao District, Nakhon Ratchasima Province, Thailand.

    PubMed

    Keawrayup, S; Duvallet, G; Sukonthabhirom, S; Chareonviriyaphap, T

    2012-08-01

    A study of species diversity of Stomoxys spp. and diurnal variations of activity of the most abundant was performed during a one year period at a local dairy cattle farm in Wang Nam Khiao District, Nakhon Ratchasima Province, Thailand. Four species of stomoxyine flies were morphologically identified, including Stomoxys indicus Picard 1908, S. calcitrans (Linnaeus 1758), S. sitiens Rondani 1873 and S. uruma Shinonaga and Kanao 1966. The most common species were S. indicus (50.2%) and S. calcitrans (49.5%). S. sitiens and S. uruma were found in small proportions (< 1%). The number of flies captured was significantly different among the three seasons with the greatest number in the rainy season (mean = 66%; df = 2, P < 0.05). The variations of diurnal activity were observed during different period of times (06:00 to 18:00) during three seasons. Both sexes of S. indicus and males of S. calcitrans showed unimodal activity pattern in cool and summer seasons. But a bimodal activity pattern was recorded in rainy season. For females S. calcitrans, a unimodal peak of activity was observed in cool season and a constant variation of activity all along the day in summer and rainy seasons, with an increase from the morning to the evening. A better understanding of stomoxyine fly behavior, especially the daily flight activity, can assist in prioritization and design of appropriate vector prevention and control strategies. PMID:22910668

  14. Magnetic Cloud Polarity and Geomagnetic Activities over Three Solar Cycles

    NASA Astrophysics Data System (ADS)

    Li, Y.; Luhmann, J.

    2006-12-01

    Interplanetary coronal mass ejections (ICMEs) that show fluxrope magnetic structures are named magnetic clouds (MCs). Majority of the MCs exhibit bipolar signature in their north-south component (Bz) in IMF measurements. The Bz component of a bipolar cloud is either NS (north first then turning south as the MC traverses the spacecraft) or SN. Studies show that the occurrence of these two types of MCs has some solar cycle dependence. However it appears to be a complex relationship as the switch between the two types of MCs is not concurrent with either the solar polar reversal or the time of the sunspot minimum when the new cycle sunspots start to appear. In this paper, we use ACE solar wind and IMF observations to obtain the most updated MC signatures and their temporal variation. In combination with our previously published results, we analyze MC polarity variations over the three solar cycles of 21, 22 and 23. Interpretations in terms of their solar sources will be attempted. On the other hand, the geomagnetic activities over the same solar cycles will be studied using geomagnetic indices. The geoeffectiveness of the MC will be evaluated in the aid of Dst indices.

  15. Estrus cycle effect on muscle tyrosine kinase activity in bitches.

    PubMed

    Gomes Pöppl, Álan; Costa Valle, Sandra; Hilário Díaz González, Félix; de Castro Beck, Carlos Afonso; Kucharski, Luiz Carlos; Silveira Martins Da Silva, Roselis

    2012-03-01

    Estrus cycle is a well recognized cause of insulin resistance in bitches. The insulin receptor (IR) as well as the insulin-like growth factor-I receptor belong to the same subfamily of tyrosine kinase (TK) receptors. The objective of this study was to evaluate basal TK activity in muscle tissue of bitches during the estrus cycle. Twenty-four bitches were used in the study (7 in anestrus, 7 in estrus, and 10 in diestrus). Muscle samples, taken after spaying surgery to determine TK activity, were immediately frozen in liquid nitrogen and then stored at -80°C until the membranes were prepared by sequential centrifugation after being homogenized. TK activity was determined by Poly (Glu 4:Tyr 1) phosphorylation and expressed in cpm/μg of protein. TK activity was significantly lower (P < 0.001) in the animals in estrus (104.5 ± 11.9 cpm/μg of protein) and diestrus (94.5 ± 16.9 cpm/μg of protein) when compared with bitches in anestrus (183.2 ± 39.2 cpm/μg of protein). These results demonstrate, for the first time, lower basal TK activity in the muscle tissue of female dogs during estrus and diestrus, which may represent lower insulin signaling capacity, opening a new field of investigation into the molecular mechanisms of insulin resistance in dogs. PMID:22139063

  16. The Cell Cycle: An Activity Using Paper Plates to Represent Time Spent in Phases of the Cell Cycle

    ERIC Educational Resources Information Center

    Scherer, Yvette D.

    2014-01-01

    In this activity, students are given the opportunity to combine skills in math and geometry for a biology lesson in the cell cycle. Students utilize the data they collect and analyze from an online onion-root-tip activity to create a paper-plate time clock representing a 24-hour cell cycle. By dividing the paper plate into appropriate phases of…

  17. Diurnal Variation of Precipitation During MC3E Campaign

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Wu, Di; Matsui, Toshi; Peters-Lidard, Christa; Hou, Arthur; Rienecker, Michele

    2012-01-01

    The diurnal variation of precipitation processes in the United States (US) is well recognized but incompletely understood (Cabone et al. 2002). The diurnal cycle of precipitation has been studied using surface rainfall data, radar reflectivity data, and satellite-derived cloudiness and precipitation (Wallace 1975; Dai et al. 1999; Carbone et al. 2002; Carbone and Tuttle, 2008; Parker and Ahijevych, 2007; Matsui et al. 2010 and others). These observations indicate that the summer-time precipitation most of the North America and typically feature late-afternoon precipitation maxima. These diurnal variation of precipitation can also be generally categorized into three different types: 1) afternoon rainfall maxima due to mesoscale and local circulations over the south and east of the Mississippi and Ohio valleys, 2) nocturnal rainfall maxima from eastward-propagating mesoscale convective systems (MCSs) over the Lee side of Rocky Mountain regions and 3) afternoon rainfall maxima in the Appalachian Mountains, and then propagate eastward toward the coast. The main objective of this paper is to use a regional cloud-scale model with very high-resolution (i.e., WRF) to examine the WRF ability to simulate diurnal variation of precipitation. Specifically, the study will (1) identify the physical processes responsible to diurnal variation of precipitation, (2) examine the sensitivity of resolution (2, 6, 18, and 30 km) to model simulated diurnal variation of precipitation and (3) identify the relationships between microphysics and cumulus parameterization schemes.

  18. Changes in the activity budget of cycling female chimpanzees.

    PubMed

    Matsumoto-Oda, A; Oda, R

    1998-01-01

    This study is a preliminary report on the time allocated to various activities by female wild chimpanzees (Pan troglodytes schweinfurthii) during their sexual cycle. Cycling females with maximal tumescence (estrous females) tended to spend more time moving than cycling females with quiescent sexual skin (anestrous females). Although there was no statistically significant decrease in any specific activity that corresponded to the increase in time spent moving, feeding time did decrease in four of the five females. The frequency of approach by females toward males and the frequency of approach by males toward females significantly increased when females were in estrus. Direct aggression by males occurred more frequently toward estrous females than toward anestrous females. The copulation frequency and the frequency of approach to males was not significantly correlated with the increase in time spent moving. There was a high but not significant correlation between the time spent moving and the frequency of direct aggression by males toward females. Mating effort, feeding competition, male aggression, and other possible reasons that might explain the increase in moving time are discussed. PMID:9773678

  19. Solar Activity in the Green Corona Over Cycle 23

    NASA Astrophysics Data System (ADS)

    Rušin, V.

    2006-12-01

    The intensity of the green coronal line (5303Å, Fe {\\sc xiv), which is directly proportional to the electron density as well as the temperature of the corona, is a good and sensitive indicator of the reflection of the photospheric activity in the emission corona, mapping also the evolution of the magnetic fields in the active regions on the solar surface. In cycle 23 (1996 -2007), the average intensity of the green corona was of about 30% less when compared with that of the preceding cycle; this, however, does not necessarily imply a lower temperature of the corona, but rather a smaller number of active regions and/or smaller strength of local magnetic fields in the latter. The maximum of the intensity of the green corona was observed in August 2001, preceding for about one and a half year that of sunspot number. Moreover, the increased intensities were not observed continuously in time and heliographic latitude, but rather in particular latitudes, with a slight time-lag between the north and south hemispheres. It is well known that a time-latitudinal distribution of the intensity of the green corona features two kinds of large-scale motions. The first is the so-called polar branch, which separates from the "main flow" in the middle latitudes in the cycle minimum, lasts for about 3 -4 years and disappears at the time of the maxima of solar activity near the poles. The other is the equatorial (or principal) branch, which after separation in middle-latitudes moves first towards the poles, then roughly 2 years after the polar branch reached the poles makes a U-turn at upper heliographic latitudes of ±70 degrees, and migrates towards the equator where it disappears in the next minimum; the life-time of this branch is about 18 years. Given the time of the splitting of the two branches, we can guess the time of the maximum and minimum of the forthcoming cycle - cycle 24: the corresponding numbers are 2011 and 2012.5 for the time of the "double" maximum and 2019 for

  20. The variations of prominence activities during solar cycle

    NASA Astrophysics Data System (ADS)

    Shimojo, Masumi

    The prominence activities (prominence eruption/disappearance) in the solar atmosphere closely relate with the CMEs that cause great influences on heliosphere and magnetosphere. Gopal-swarmy et al. (2003) reported that 72 The Nobeyama Radioheliograph (NoRH) is observing Sun in microwave (17 GHz) since 1992. At a flare, the main component of the microwave from Sun is emitted from non-thermal electrons that are accelerated by flare. On the other hand, the main component of the microwave is thermal emission when Sun is quiet, and a prominence is clearly observed in microwave because there is the prominence on the limb. We developed the automatic prominence activity detection program based on 17 GHz images observed by NoRH, and investigated the variation of the properties of the prominence activities that oc-curred from 1992 to the end of 2009. We found the following results. 1. The variation in the number of prominence activities is similar to that of sunspots during one solar cycle but there are differences between the peak times of prominence activities and sunspots. 2. The frequency distribution as a function of the magnitude of the prominence activities the size of activated prominences at each phase shows a power-law distribution. The power-law index of the distribution does not change except around the solar minimum. 3. The number of promi-nence activities has a dependence on the latitude On the other hand the average magnitude is independent of the latitude. In the paper, we will also discuss the relationship the other properties of prominence eruptions, solar cycle and the photospheric magnetic field.

  1. Synthesis and degradation of nitrate reductase during the cell cycle of Chlorella sorokiniana

    NASA Technical Reports Server (NTRS)

    Velasco, P. J.; Tischner, R.; Huffaker, R. C.; Whitaker, J. R.

    1989-01-01

    Studies on the diurnal variations of nitrate reductase (NR) activity during the life cycle of synchronized Chlorella sorokiniana cells grown with a 7:5 light-dark cycle showed that the NADH:NR activity, as well as the NR partial activities NADH:cytochrome c reductase and reduced methyl viologen:NR, closely paralleled the appearance and disappearance of NR protein as shown by sodium dodecyl sulfate gel electrophoresis and immunoblots. Results of pulse-labeling experiments with [35S]methionine further confirmed that diurnal variations of the enzyme activities can be entirely accounted for by the concomitant synthesis and degradation of the NR protein.

  2. Effects of solar cycle 24 activity on WAAS navigation

    NASA Astrophysics Data System (ADS)

    Datta-Barua, Seebany; Walter, Todd; Bust, Gary S.; Wanner, William

    2014-01-01

    This paper reviews the effects of geomagnetic activity of solar cycle 24 from 2011 through mid-2013 on the Federal Aviation Administration's Wide Area Augmentation System (WAAS) navigation service in the U.S., to identify (a) major impacts and their severity compared with the previous cycle and (b) effects in new service regions of North America added since last solar cycle. We examine two cases: a storm that reduced service coverage for several hours and ionospheric scintillation that led to anomalous receiver tracking. Using the 24-25 October 2011 storm as an example, we examine WAAS operational system coverage for the conterminous U.S. (CONUS). The WAAS algorithm upgrade to ionospheric estimation, in effect since late 2011, is able to mitigate the daytime coverage loss but not the nighttime loss. We correlate WAAS availability to maps of the storm plasma generated with the data assimilative model Ionospheric Data Assimilation 4-D, which show a local nighttime corotating persistent plume of plasma extending from Florida across central CONUS. We study the effect of scintillation on 9 October 2012 on the WAAS reference station at Fairbanks, Alaska. Data from a nearby scintillation monitor in Gakona and all-sky imaging of aurora at Poker Flat corroborate the event. Anomalous receiver processing triggered by scintillation reduces accuracy at Fairbanks for a few minutes. Users experiencing similar effects would have their confidence bounds inflated, possibly trading off service continuity for safety. The activity to date in solar cycle 24 has had minor effects on WAAS service coverage, mainly occurring in Alaska and Canada.

  3. Diurnal patterns of blowing sand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The diurnal pattern of blowing sand results from a complex process that involves an interaction between solar heating, thermal instability, atmospheric turbulence, wind strength, and surface threshold conditions. During the day, solar heating produces thermal instability, which enhances the convect...

  4. Diurnal nitrogen excretion rhythm of the functionally ureogenic gobiid fish Mugilogobius abei.

    PubMed

    Kajimura, Makiko; Iwata, Katsuya; Numata, Hideharu

    2002-02-01

    This study was performed to determine the daily periodicity of urea excretion in the ureogenic gobiid fish Mugilogobius abei. In 20% seawater, urea excretion of all the fish examined showed daily periodic changes under a 12-h light-dark cycle, and some showed a free-running rhythm under constant darkness. This is the first report of a circadian rhythm in urea excretion in fishes. Daily variations in urea excretion under light-dark cycles were also observed under various conditions, i.e. exposure to water ammonia, confinement/non-confinement and solitary/group. Due to the daily variations in urea excretion, urea contents in tissues changed periodically, whereas enzyme activities related to urea synthesis did not change significantly. The index of urea permeability as determined by changes in body urea contents after 2-h immersion of 25 mM urea solution was high during the peak of daily variation in urea excretion. Locomotor activity and urea excretion showed clear daily variations under light-dark cycles, both of which were diurnal. Furthermore, daily variations in urea excretion were maintained even when the diurnal pattern in the locomotor activity was disturbed. These results suggest that periodic urea excretion was mediated by periodic enhancement of permeability for urea at excretion sites. PMID:11818244

  5. Shifting Nicotiana attenuata's diurnal rhythm does not alter its resistance to the specialist herbivore Manduca sexta.

    PubMed

    Herden, Jasmin; Meldau, Stefan; Kim, Sang-Gyu; Kunert, Grit; Joo, Youngsung; Baldwin, Ian T; Schuman, Meredith C

    2016-07-01

    Arabidopsis thaliana plants are less resistant to attack by the generalist lepidopteran herbivore Trichoplusia ni when plants and herbivores are entrained to opposite, versus identical diurnal cycles and tested under constant conditions. This effect is associated with circadian fluctuations in levels of jasmonic acid, the transcription factor MYC2, and glucosinolate contents in leaves. We tested whether a similar effect could be observed in a different plant-herbivore system: the wild tobacco Nicotiana attenuata and its co-evolved specialist herbivore, Manduca sexta. We measured larval growth on plants under both constant and diurnal conditions following identical or opposite entrainment, profiled the metabolome of attacked leaf tissue, quantified specific metabolites known to reduce M. sexta growth, and monitored M. sexta feeding activity under all experimental conditions. Entrainment did not consistently affect M. sexta growth or plant defense induction. However, both were reduced under constant dark conditions, as was M. sexta feeding activity. Our data indicate that the response induced by M. sexta in N. attenuata is robust to diurnal cues and independent of plant or herbivore entrainment. We propose that while the patterns of constitutive or general damage-induced defense may undergo circadian fluctuation, the orchestration of specific induced responses is more complex. PMID:26699809

  6. A new simple dynamo model for solar activity cycle

    NASA Astrophysics Data System (ADS)

    Yokoi, Nobumitsu; Schmitt, Dieter

    2015-04-01

    The solar magnetic activity cycle has been investigated in an elaborated manner with several types of dynamo models [1]. In most of the current mean-field approaches, the inhomogeneity of the large-scale flow is treated as an essential ingredient in the mean magnetic field equation whereas it is completely neglected in the turbulence equation. In this work, a new simple model for the solar activity cycle is proposed. The present model differs from the previous ones mainly in two points. First, in addition to the helicity coefficient α, we consider a term related to the cross helicity, which represents the effect of the inhomogeneous mean flow, in the turbulent electromotive force [2, 3]. Second, this transport coefficient (γ) is not treated as an adjustable parameter, but the evolution equation for γ is simultaneously solved. The basic scenario for the solar activity cycle in this approach is as follows: The toroidal field is induced by the toroidal rotation in mediation by the turbulent cross helicity. Then due to the α or helicity effect, the poloidal field is generated from the toroidal field. The poloidal field induced by the α effect produces a turbulent cross helicity whose sign is opposite to the original one (negative cross-helicity production). The cross helicity with this opposite sign induces a reversed toroidal field. Results of the eigenvalue analysis of the model equations are shown, which confirm the above scenario. References [1] Charbonneau, Living Rev. Solar Phys. 7, 3 (2010). [2] Yoshizawa, A. Phys. Fluids B 2, 1589 (1990). [3] Yokoi, N. Geophys. Astrophys. Fluid Dyn. 107, 114 (2013).

  7. Sunspot Activity Near Cycle Minimum and What it Might Suggest for Cycle 24, the Next Sunspot Cycle

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.

    2009-01-01

    In late 2008, 12-month moving averages of sunspot number, number of spotless days, number of groups, area of sunspots, and area per group were reflective of sunspot cycle minimum conditions for cycle 24, these values being of or near record value. The first spotless day occurred in January 2004 and the first new-cycle, high-latitude spot was reported in January 2008, although old-cycle, low-latitude spots have continued to be seen through April 2009, yielding an overlap of old and new cycle spots of at least 16 mo. New-cycle spots first became dominant over old-cycle spots in September 2008. The minimum value of the weighted mean latitude of sunspots occurred in May 2007, measuring 6.6 deg, and the minimum value of the highest-latitude spot followed in June 2007, measuring 11.7 deg. A cycle length of at least 150 mo is inferred for cycle 23, making it the longest cycle of the modern era. Based on both the maximum-minimum and amplitude-period relationships, cycle 24 is expected to be only of average to below-average size, peaking probably in late 2012 to early 2013, unless it proves to be a statistical outlier.

  8. Sources of solar wind over the solar activity cycle.

    PubMed

    Poletto, Giannina

    2013-05-01

    Fast solar wind has been recognized, about 40 years ago, to originate in polar coronal holes (CHs), that, since then, have been identified with sources of recurrent high speed wind streams. As of today, however, there is no general consensus about whether there are, within CHs, preferential locations where the solar wind is accelerated. Knowledge of slow wind sources is far from complete as well. Slow wind observed in situ can be traced back to its solar source by backward extrapolation of magnetic fields whose field lines are streamlines of the outflowing plasma. However, this technique often has not the necessary precision for an indisputable identification of the region where wind originates. As the Sun progresses through its activity cycle, different wind sources prevail and contribute to filling the heliosphere. Our present knowledge of different wind sources is here summarized. Also, a Section addresses the problem of wind acceleration in the low corona, as inferred from an analysis of UV data, and illustrates changes between fast and slow wind profiles and possible signatures of changes along the solar cycle. A brief reference to recent work about the deep roots of solar wind and their changes over different solar cycles concludes the review. PMID:25685421

  9. Inferring land surface parameters from the diurnal variability of microwave and infrared temperatures

    NASA Astrophysics Data System (ADS)

    Norouzi, Hamidreza; Temimi, Marouane; AghaKouchak, Amir; Azarderakhsh, Marzieh; Khanbilvardi, Reza; Shields, Gerarda; Tesfagiorgis, Kibrewossen

    This study investigates the properties of the diurnal cycle of microwave brightness temperatures (TB), namely the phase and the amplitude, and their variability in time and space over the globe to infer information on key land surface parameters like changes in soil texture spatial distribution, soil moisture conditions, and vegetation density. The phase corresponds to the lag between Land Surface Temperature (LST) and TB diurnal cycles. The amplitude is determined as the difference between the maximum and the minimum of TB diurnal cycle. The diurnal cycle of TB was constructed using observations from the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) and the Special Sensor Microwave/Imager (SSM/I). The latter offer a series of sensors, namely, F13, F14, and F15 that were used in this study for a higher temporal coverage and more accurate diurnal cycle determination. LST estimates, which are available every 3 h from the International Satellite Cloud Climatology Project (ISCCP) database were used to build the LST diurnal cycle. ISCCP LST data is an infrared-based temperature with almost no penetration and is the representative of top skin temperature. The analyses of the diurnal cycles showed that the diurnal amplitude of TB decreases as the vegetation density increases, especially in the case of low frequencies which penetrate deeper into the canopy which makes them more sensitive to changes in vegetation density. The interannual variations of TB diurnal amplitudes were also in agreement with the seasonality of the vegetation cover. Over desert and rain forest regions where surface conditions do not vary significantly throughout the year, the changes in diurnal amplitudes were the lowest. A relationship between phase and amplitude values was established. It was found that the amplitude of TB diurnal cycle decreases when the phase lag increases. The spatial distribution of the determined diurnal properties, namely, phase and amplitude of TB

  10. A diurnal serum lipid integrates hepatic lipogenesis and peripheral fatty acid utilization

    PubMed Central

    Liu, Sihao; Brown, Jonathan D.; Stanya, Kristopher J.; Homan, Edwin; Leidl, Mathias; Inouye, Karen; Bhargava, Prerna; Gangl, Matthew R.; Dai, Lingling; Hatano, Ben; Hotamisligil, Gökhan S.; Saghatelian, Alan; Plutzky, Jorge; Lee, Chih-Hao

    2014-01-01

    Food intake increases the activity of hepatic de novo lipogenesis, which mediates the conversion of glucose to fats for storage or utilization. In mice, this program follows a circadian rhythm that peaks with nocturnal feeding1,2 and is repressed by Rev-erbα/β and an HDAC3-containing complex3–5 during the day. The transcriptional activators controlling rhythmic lipid synthesis in the dark cycle remain poorly defined. Disturbances in hepatic lipogenesis are also associated with systemic metabolic phenotypes6–8, suggesting that lipogenesis in the liver communicates with peripheral tissues to control energy substrate homeostasis. Here we identify a PPARδ-dependent de novo lipogenic pathway in the liver that modulates fat utilization by muscle via a circulating lipid. The nuclear receptor PPARδ controls diurnal expression of lipogenic genes in the dark/feeding cycle. Liver-specific PPARδ activation increases, while hepatocyte-Ppard deletion reduces, muscle fatty acid (FA) uptake. Unbiased metabolite profiling identifies PC(18:0/18:1), or 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC), as a serum lipid regulated by diurnal hepatic PPARδ activity. PC(18:0/18:1) reduces postprandial lipid levels and increases FA utilization through muscle PPARα. High fat feeding diminishes rhythmic production of PC(18:0/18:1), whereas PC(18:0/18:1) administration in db/db mice improves metabolic homeostasis. These findings reveal an integrated regulatory circuit coupling lipid synthesis in the liver to energy utilization in muscle by coordinating the activity of two closely related nuclear receptors. These data implicate alterations in diurnal hepatic PPARδ-PC(18:0/18:1) signaling in metabolic disorders including obesity. PMID:24153306

  11. Cardiovascular responses to active and passive cycling movements.

    PubMed

    Nóbrega, A C; Williamson, J W; Friedman, D B; Araújo, C G; Mitchell, J H

    1994-06-01

    Ten healthy subjects were evaluated at rest and at 5 min of unloaded active (AC) and passive (PC) cycling. Passive limb movements were accomplished using a tandem bicycle with a second rider performing the movements. We measured heart rate (HR), mean arterial pressure (MAP), cardiac output (CO), oxygen uptake (VO2), rating of perceived exertion (RPE), and electrical activity (EMG) of lower limbs muscles. Values for stroke volume (SV) and peripheral vascular resistance (PVR) were calculated. EMG, RPE, and VO2 were higher during AC than during PC (P < 0.001). CO increased during both modes of cycling, but during AC it resulted from a HR acceleration (73 +/- 2 at rest to 82 +/- 2 beats.min-1 at 60 rpm; P < 0.001) with no change in SV whereas during PC, SV increased from rest (65 +/- 4 at rest to 71 +/- 3 ml at 60 rpm; P = 0.003) along with no change in HR. PVR remained constant during PC, but decreased by 13% during AC (P < 0.001) and MAP increased only during PC (93 +/- 2 at rest to 107 +/- 2 mm Hg at 60 rpm). These results supports the concept that central command determines the HR response to dynamic exercise. The increase in SV and consequently in MAP during PC was probably due to increased venous return and/or to muscle mechanoreceptor-evoked increased myocardial contractility. PMID:8052111

  12. Lidar observation campaigns on diurnal variations of the sodium layer in Beijing, China

    NASA Astrophysics Data System (ADS)

    Wang, Jihong

    2016-07-01

    Based on observations from daytime lidars in eastern China, diurnal cycles of the sodium layer over Beijing (40.5°N, 116°E) are investigated. Diurnal variations of Na density, root mean square (RMS) layer width, and centroid height of the sodium layer are analyzed. Results reveal that the large diurnal cycles of the sodium layer are controlled mainly by 24-hr oscillations at the Beijing observation site. The diurnal variation over Beijing was controlled principally by photoionization and photochemistry effects during another campaign, and there was little evidence of direct tidal perturbations. The comparisons suggest that the diurnal variation of the sodium layer perhaps has obvious regional characteristics across China. The variation can be either controlled mainly by tidal perturbations or by photoionization and photochemistry effects in different seasons.

  13. Chromospheric and coronal variation across stellar activity cycles

    NASA Astrophysics Data System (ADS)

    Hagen, Cedric; Miller, Brendan P.; Gallo, Elena; Wright, Jason; Isaacson, Howard T.; Henry, Gregory W.

    2015-01-01

    We investigate cyclic chromospheric and coronal activity in main-sequence stars, using Ca II H and K core emission and X-ray luminosities, respectively. From a sample of 244 nearby stars with high-cadence Keck optical spectroscopy spanning up to 17 years (obtained for the California Planet Search program), we use automated sinusoid modeling and goodness-of-fit criteria to identify 33 stars with highly significant cyclic R'HK variability. The cycle periods are refined using mmag APT optical photometry. We also construct a comparison sample of 23 stars that show virtually no R'HK variability. The cyclic and flat stars have similar B-V and absolute magnitude distributions but the cyclic stars tend to be more active, with greater median R'HK values. We present new Swift/XRT observations of 10 cyclic stars and 1 flat star, totaling 32.6 ks; 5/11 are detected in this snapshot pilot survey. A comparison of their current-epoch X-ray luminosities to archival ROSAT values shows variation by a factor of 2-3 is common on decade-long timescales. Several stars also show suggestive evidence for X-ray variability on much shorter timescales, perhaps related to stellar rotation and coronal inhomogeneity or to small flares. We use the chromospheric activity cycles to calculate the phase of each X-ray observation. Additional Swift observations are ongoing and with this larger dataset we will measure the typical amplitude of cyclic X-ray variation. We discuss our initial results in the context of magnetic dynamo activity and consider the implications for exoplanet atmosphere heating and evaporation.

  14. The Sequence of Learning Cycle Activities in High School Chemistry.

    ERIC Educational Resources Information Center

    Abraham, Michael R.; Renner, John W.

    1986-01-01

    Different learning cycle sequences were investigated to determine factors accounting for success of the cycle, compared learning with conventional instruction, and examined relationships between Piaget's theory and learning cycles. Results show that the normal learning cycle sequence is the optimum sequence for achievement of content knowledge in…

  15. Quantifying the diurnal variability of deep convection in the Congo basin using satellite observations, global and regional models.

    NASA Astrophysics Data System (ADS)

    White, Bethan; Kipling, Zak; Taylor, Sarah; Stier, Philip

    2015-04-01

    Convection transports moisture, momentum, heat and aerosols through the troposphere, and so the temporal variability of convection is a major driver of global weather and climate. The diurnal cycle of convection is associated with large variations in solar forcing and the ability of models to represent this cycle shows how well they represent radiative transfer and surface heat exchanges, as well as boundary layer, convective and cloud processes. Global models and some numerical weather prediction (NWP) models fail to capture the observed diurnal cycle of convection (Yang and Slingo, 2001; Stratton and Stirling, 2012), while the ability of cloud-resolving models (CRMs) to represent the diurnal cycle is strongly dependent on horizontal resolution. The Congo basin is home to some of the most intense convective activity on the planet, yet has been the focus of very few previous studies, especially when compared to the neighbouring, relatively well-understood West African climate system. Ground-based observations of convection and precipitation in the Congo region are sparse, and there has been a sharp decline in the number of rain gauges in the region over the past few decades (Washington, 2013). In this study we use a variety of tools to quantify the diurnal cycle of deep convection over the Congo including satellite observations, a global model both with and without a new convective parameterisation, and a regional convection-permitting model. This approach allows us to evaluate our simulations despite the lack of in-situ observational data. In contrast to the static picture provided by polar-orbiting satellites, the geostationary SEVIRI instrument provides continuous, high time resolution observations of cloud properties over a large area. It has the additional advantage of providing coverage of the Congo Basin, at a spatial resolution of between 3 and 5km. The CLAAS (Cloud Property Dataset Using SEVIRI) product is used to quantify the diurnal cycle of convective

  16. Diurnal precipitation and high cloud frequency variability over the Gulf Stream and over the Kuroshio

    NASA Astrophysics Data System (ADS)

    Minobe, Shoshiro; Takebayashi, Shogo

    2015-04-01

    Recent studies show mid-latitude western boundary currents (WBCs) substantially influence the atmosphere aloft, and an important feature is enhanced rain band over the WBCs in climatological mean field. However, how such long-term, climate phenomena are related to shorter, weather timescale phenomena are generally remained to be explored. In this paper, diurnal precipitation and cloud variations are investigated global mid-latitude oceans with emphasis on air-sea interactions over WBCs using satellite-derived precipitation and outgoing longwave radiation (OLR) datasets. Strong 24-h period components of precipitations are found over the Gulf Stream in summer and over the Kuroshio in the East China Sea in early summer (Baiu-Meiyu season), respectively. Similar diurnal precipitations are not observed in WBCs in the Southern Hemisphere year around. The diurnal precipitation cycles over the Gulf Stream and the Kuroshio exhibit peak phases in the early to late morning for the Gulf Stream and late morning to early afternoon for the Kuroshio, with southeastward phase propagations. High cloud frequency derived from OLR data exhibit consistent diurnal cycles. A substantial difference of diurnal cycles between the Gulf Stream and the Kuroshio regions are associated with the large-scale Baiu-Meiyu rain and cloud bands for the latter region. Diurnal precipitation and high cloud variability is found in the vicinity of the Kuroshio itself, embedded in the Baiu-Meiyu rain and cloud bands distributing in a wider area without a strong diurnal component. The spatial and seasonal distributions of the diurnal variability over these WBCs strongly suggests that the diurnal precipitation and cloud cycles are essential aspects of deep heating mode of atmospheric response recently reported for these WBCs. These results indicate that these WBCs in the Northern Hemisphere play an important role in modulating short-term precipitation variations, and on the other hand diurnal variability can be

  17. Diurnal Rhythms Result in Significant Changes in the Cellular Protein Complement in the Cyanobacterium Cyanothece 51142

    SciTech Connect

    Stockel, Jana; Jacobs, Jon M.; Elvitigala, Thanura R.; Liberton, Michelle L.; Welsh, Eric A.; Polpitiya, Ashoka D.; Gritsenko, Marina A.; Nicora, Carrie D.; Koppenaal, David W.; Smith, Richard D.; Pakrasi, Himadri B.

    2011-02-22

    Cyanothece sp. ATCC 51142 is a diazotrophic cyanobacterium notable for its ability to perform oxygenic photosynthesis and dinitrogen fixation in the same single cell. Previous transcriptional analysis revealed that the existence of these incompatible cellular processes largely depends on tightly synchronized expression programs involving ,30% of genes in the genome. To expand upon current knowledge, we have utilized sensitive proteomic approaches to examine the impact of diurnal rhythms on the protein complement in Cyanothece 51142. We found that 250 proteins accounting for,5% of the predicted ORFs from the Cyanothece 51142 genome and 20% of proteins detected under alternating light/dark conditions exhibited periodic oscillations in their abundances. Our results suggest that altered enzyme activities at different phases during the diurnal cycle can be attributed to changes in the abundance of related proteins and key compounds. The integration of global proteomics and transcriptomic data further revealed that post-transcriptional events are important for temporal regulation of processes such as photosynthesis in Cyanothece 51142. This analysis is the first comprehensive report on global quantitative proteomics in a unicellular diazotrophic cyanobacterium and uncovers novel findings about diurnal rhythms.

  18. Effects of Low Activity Solar Cycle on Orbital Debris Lifetime

    NASA Technical Reports Server (NTRS)

    Cable, Samual B.; Sutton, Eric K.; Lin, chin S.; Liou, J.-C.

    2011-01-01

    Long duration of low solar activity in the last solar minimum has an undesirable consequence of extending the lifetime of orbital debris. The AFRL TacSat-2 satellite decommissioned in 2008 has finally re-entered into the atmosphere on February 5th after more than one year overdue. Concerning its demise we have monitored its orbital decay and monthly forecasted Tacsat-2 re-entry since September 2010 by using the Orbital Element Prediction (OEP) model developed by the AFRL Orbital Drag Environment program. The model combines estimates of future solar activity with neutral density models, drag coefficient models, and an orbit propagator to predict satellite lifetime. We run the OEP model with solar indices forecast by the NASA Marshall Solar Activity Future Estimation model, and neutral density forecast by the MSIS-00 neutral density model. Based on the two line elements in 2010 up to mid September, we estimated at a 50% confidence level TacSat-2's re-entry time to be in early February 2011, which turned out to be in good agreement with Tacsat-2's actual re-entry date. The potential space weather effects of the coming low activity solar cycle on satellite lifetime and orbital debris population are examined. The NASA long-term orbital debris evolutionary model, LEGEND, is used to quantify the effects of solar flux on the orbital debris population in the 200-600 km altitude environment. The results are discussed for developing satellite orbital drag application product.

  19. Genipin as a novel chemical activator of EBV lytic cycle.

    PubMed

    Son, Myoungki; Lee, Minjung; Ryu, Eunhyun; Moon, Aree; Jeong, Choon-Sik; Jung, Yong Woo; Park, Gyu Hwan; Sung, Gi-Ho; Cho, Hyosun; Kang, Hyojeung

    2015-02-01

    Epstein-Barr virus (EBV) is a ubiquitous gammaherpesvirus that causes acute infection and establishes life-long latency. EBV causes several human cancers, including Burkitt's lymphoma, nasopharyngeal and gastric carcinoma. Antiviral agents can be categorized as virucides, antiviral chemotherapeutic agents, and immunomodulators. Most antiviral agents affect actively replicating viruses, but not their latent forms. Novel antiviral agents must be active on both the replicating and the latent forms of the virus. Gardenia jasminoides is an evergreen flowering plant belonging to the Rubiaceae family and is most commonly found growing wild in Vietnam, Southern China, Taiwan, Japan, Myanmar, and India. Genipin is an aglycone derived from an iridoid glycoside called geniposide, which is present in large quantities in the fruit of G. jasminoides. In this study, genipin was evaluated for its role as an antitumor and antiviral agent that produces inhibitory effects against EBV and EBV associated gastric carcinoma (EBVaGC). In SNU719 cells, one of EBVaGCs, genipin caused significant cytotoxicity (70 μM), induced methylation on EBV C promoter and tumor suppressor gene BCL7A, arrested cell-cycle progress (S phases), upregulated EBV latent/lytic genes in a dose-dependent manner, stimulated EBV progeny production, activated EBV F promoter for EBV lytic activation, and suppressed EBV infection. These results indicated that genipin could be a promising candidate for antiviral and antitumor agents against EBV and EBVaGC. PMID:25626372

  20. Global changes in biogeochemical cycles in response to human activities

    NASA Technical Reports Server (NTRS)

    Moore, Berrien, III; Melillo, Jerry

    1994-01-01

    The main objective of our research was to characterize biogeochemical cycles at continental and global scales in both terrestrial and aquatic ecosystems. This characterization applied to both natural ecosystems and those disturbed by human activity. The primary elements of interest were carbon and nitrogen and the analysis sought to quantify standing stocks and dynamic cycling processes. The translocation of major nutrients from the terrestrial landscape to the atmosphere (via trace gases) and to fluvial systems (via leaching, erosional losses, and point source pollution) were of particular importance to this study. Our aim was to develop the first generation of Earth System Models. Our research was organized around the construction and testing of component biogeochemical models which treated terrestrial ecosystem processes, aquatic nutrient transport through drainage basins, and trace gas exchanges at the continental and global scale. A suite of three complementary models were defined within this construct. The models were organized to operate at a 1/2 degree latitude by longitude level of spatial resolution and to execute at a monthly time step. This discretization afforded us the opportunity to understand the dynamics of the biosphere down to subregional scales, while simultaneously placing these dynamics into a global context.

  1. Residential construction demonstration project, Cycle II: Active ventilation

    SciTech Connect

    Not Available

    1991-01-01

    This report documents the analysis of the performance of natural and mechanical ventilation in Pacific Northwest homes. The analysis was part of Cycle II of the Residential Construction Demonstration Project, sponsored by Bonneville Power Administration (BPA). Since 1986, the Residential Construction Demonstration Project (RCDP) has sponsored the collection of data on energy efficient homes in the Pacific Northwest that comply with these new standards and requirements. Cycle II of RCDP was conducted between September 1987 and April 1990. It concentrated on energy innovations in homes built to the Super Good Cents specification. All of the test homes have electric heat and mechanical ventilation systems. Seven different types of active ventilation systems are represented in the homes. Three of these system types are equipped with heat recovery devices, and are represented in approximately a quarter of the test homes. The potential for both natural and mechanical ventilation was measured. Potential structural leakage was measured by blower door testing. Flow rate and operating time of mechanical ventilation systems were measured with flow hoods and hour meters. Actual ventilation was measured by using a passive tracer gas technique for several weeks during the heating season and at times of normal occupancy.

  2. Residential construction demonstration project, Cycle II: Active ventilation

    SciTech Connect

    Not Available

    1991-12-31

    This report documents the analysis of the performance of natural and mechanical ventilation in Pacific Northwest homes. The analysis was part of Cycle II of the Residential Construction Demonstration Project, sponsored by Bonneville Power Administration (BPA). Since 1986, the Residential Construction Demonstration Project (RCDP) has sponsored the collection of data on energy efficient homes in the Pacific Northwest that comply with these new standards and requirements. Cycle II of RCDP was conducted between September 1987 and April 1990. It concentrated on energy innovations in homes built to the Super Good Cents specification. All of the test homes have electric heat and mechanical ventilation systems. Seven different types of active ventilation systems are represented in the homes. Three of these system types are equipped with heat recovery devices, and are represented in approximately a quarter of the test homes. The potential for both natural and mechanical ventilation was measured. Potential structural leakage was measured by blower door testing. Flow rate and operating time of mechanical ventilation systems were measured with flow hoods and hour meters. Actual ventilation was measured by using a passive tracer gas technique for several weeks during the heating season and at times of normal occupancy.

  3. Intertwined arbovirus transmission activity: reassessing the transmission cycle paradigm

    PubMed Central

    Diaz, Luis A.; Flores, Fernando S.; Quaglia, Agustín; Contigiani, Marta S.

    2013-01-01

    Arboviruses are emerging/reemerging infectious agents worldwide. The factors within this scenario include vector and host population fluctuations, climatic changes, anthropogenic activities that disturb ecosystems, an increase in international flights, human mobility, and genetic mutations that allow spill-over phenomenon. Arboviruses are maintained by biologic transmission among vectors and hosts. Sometimes this biological transmission is specific and includes one vector and host species such as Chikungunya (CHIKV), Dengue (DENV), and urban Yellow Fever (YFV). However, most of the arboviruses are generalist and they use many vectors and hosts species. From this perspective, arboviruses are maintained through a transmission network rather than a transmission cycle. This allows us to understand the complexity and dynamics of the transmission and maintenance of arboviruses in the ecosystems. The old perspective that arboviruses are maintained in close and stable transmission cycles should be modified by a new more integrative and dynamic idea, representing the real scenario where biological interactions have a much broader representation, indicating the constant adaptability of the biological entities. PMID:23335900

  4. Does the Neuroprotective Role of Anandamide Display Diurnal Variations?

    PubMed Central

    Martinez-Vargas, Marina; Morales-Gomez, Julio; Gonzalez-Rivera, Ruben; Hernandez-Enriquez, Carla; Perez-Arredondo, Adan; Estrada-Rojo, Francisco; Navarro, Luz

    2013-01-01

    The endocannabinoid system is a component of the neuroprotective mechanisms that an organism displays after traumatic brain injury (TBI). A diurnal variation in several components of this system has been reported. This variation may influence the recovery and survival rate after TBI. We have previously reported that the recovery and survival rate of rats is higher if TBI occurs at 1:00 than at 13:00. This could be explained by a diurnal variation of the endocannabinoid system. Here, we describe the effects of anandamide administration in rats prior to the induction of TBI at two different times of the day: 1:00 and 13:00. We found that anandamide reduced the neurological damage at both times. Nevertheless, its effects on bleeding, survival, food intake, and body weight were dependent on the time of TBI. In addition, we analyzed the diurnal variation of the expression of the cannabinoid receptors CB1R and CB2R in the cerebral cortex of both control rats and rats subjected to TBI. We found that CB1R protein was expressed more during the day, whereas its mRNA level was higher during the night. We did not find a diurnal variation for the CB2R. In addition, we also found that TBI increased CB1R and CB2R in the contralateral hemisphere and disrupted the CB1R diurnal cycle. PMID:24287910

  5. Diurnal variations in water vapor over Central and South America

    NASA Astrophysics Data System (ADS)

    Meza, Amalia; Mendoza, Luciano; Bianchi, Clara

    2016-07-01

    Diurnal variations in atmospheric integrated water vapor (IWV) are studied employing IWV estimates, with a 30 minutes sampling rate, derived from Global Navigation Satellite Systems (GNSS) observations during the period 2007-2013. The analysis was performed in 73 GNSS tracking sites (GPS + GLONASS) which have more than 5 years of data. The selected area involves different climate types, from polar to tropical, with different diurnal variations of the integrated total humidity content. There are many processes that could induce diurnal variations in atmospheric water vapor (Dai et al, 1999 a,b), the most relevant causes are: surface evapotranspiration, atmospheric large-scale vertical motion, atmospheric low-level moisture convergence and precipitation and vertical mixing (which affects the vertical distribution of water vapor but does not affect the IWV). The numerical tools, Singular Value Decomposition and classical Multidimensional Scaling methods, are used to study these variations, considering the measurements made at each stations, as sample in the analysis. The aim of this investigation is to identify the IWV variability with respect to the local time associated to the different climate regions. In order to improve our analysis, all available weather information, such as radiosondes measurements (which are few), measurements of pressure and temperature and Numerical Weather Models reanalysis data, are used. Reference: Dai, A., K. E. Trenberth, and T. R. Karl, 1999 a: Effects of clouds, soil moisture, precipitation and water vapor on diurnal temperature range. J. Climate, 12, 2451-2473. Dai, A., F. Giorgi, and K. E. Trenberth, 1999 b: Observed and model simulated precipitation diurnal cycle over the contiguous United States.J. Geophys. Res., 104, 6377-6402. KEYWORDS: water vapor, diurnal cycle, GNSS

  6. A New Simple Dynamo Model for Stellar Activity Cycle

    NASA Astrophysics Data System (ADS)

    Yokoi, N.; Schmitt, D.; Pipin, V.; Hamba, F.

    2016-06-01

    A new simple dynamo model for stellar activity cycle is proposed. By considering an inhomogeneous flow effect on turbulence, it is shown that turbulent cross helicity (velocity–magnetic-field correlation) enters the expression of turbulent electromotive force as the coupling coefficient for the mean absolute vorticity. This makes the present model different from the current α–Ω-type models in two main ways. First, in addition to the usual helicity (α) and turbulent magnetic diffusivity (β) effects, we consider the cross-helicity effect as a key ingredient of the dynamo process. Second, the spatiotemporal evolution of cross helicity is solved simultaneously with the mean magnetic fields. The basic scenario is as follows. In the presence of turbulent cross helicity, the toroidal field is induced by the toroidal rotation. Then, as in usual models, the α effect generates the poloidal field from the toroidal one. This induced poloidal field produces a turbulent cross helicity whose sign is opposite to the original one (negative production). With this cross helicity of the reversed sign, a reversal in field configuration starts. Eigenvalue analyses of the simplest possible model give a butterfly diagram, which confirms the above scenario and the equatorward migrations, the phase relationship between the cross helicity and magnetic fields. These results suggest that the oscillation of the turbulent cross helicity is a key for the activity cycle. The reversal of the cross helicity is not the result of the magnetic-field reversal, but the cause of the latter. This new model is expected to open up the possibility of the mean-field or turbulence closure dynamo approaches.

  7. On the similarity of 239Pu α-activity histograms when the angular velocities of the Earth diurnal rotation, orbital movement and rotation of collimators are equalized

    NASA Astrophysics Data System (ADS)

    Shnoll, S. E.; Rubinstein, I. A.; Shapovalov, S. N.; Tolokonnikova, A. A.; Shlektaryov, V. A.; Kolombet, V. A.; Kondrashova, M. N.

    2016-01-01

    It was shown earlier that the persistent "scatter" of results of measurements of any nature is determined by the diurnal and orbital movement of the Earth. The movement is accompanied by "macroscopic fluctuations" (MF)—regular, periodic changes in the shape of histograms, spectra of fluctuation amplitudes of the measured parameters. There are two near-daily periods ("sidereal", 1436 min; and "solar", 1440 min) and three yearly ones ("calendar", 365 average solar days; "tropical", 365 days 5 h and 48 min; and "sidereal", 365 days 6 h and 9 min). This periodicity was explained by the objects whose parameters are measured passing through the same spatial-temporal heterogeneities as the Earth rotates and shifts along its orbit.

  8. Diurnal variability of precipitation from TRMM measurements

    NASA Astrophysics Data System (ADS)

    Yang, Song; Smith, Eric A.; Kuo, Kwo-Sen

    2006-12-01

    This investigation focuses on developing a better understanding of the assorted mechanisms controlling the global distribution of diurnal rainfall variability. The horizontal distributions of precipitation's diurnal cycle, based on eight years of TRMM Microwave Imager (TMI) and TRMM Precipitation Radar (PR) measurements involving three TRMM standard algorithms, are analyzed in detail at various spatiotemporal scales. Results demonstrate the prominence of the late-evening to early-morning precipitation maxima over oceans and the mid- to late-afternoon maxima over continents, but also reveal a widespread distribution of secondary maxima occurring over both oceans and continents, maxima which generally mirror their counterpart regime's behavior. That is, many ocean regions exhibit clear-cut secondary afternoon precipitation maxima while many continental areas exhibit just as evident secondary morning maxima. Notably, this investigation represents the first comprehensive study of these secondary maxima and their widespread nature when analyzed using a global precipitation dataset. The characteristics of the secondary maxima are thoroughly mapped and described on a global grid. In addition, a Fourier harmonic decomposition scheme is used to examine detailed amplitude and phase properties of the primary and secondary maxima -- as well as tertiary and quartern modes. Accordingly, the advantages, ambiguities, and pitfalls resulting from using harmonic analysis are also examined.

  9. Diurnal patterns of blowing sand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The diurnal pattern of blowing sand results from a complex process that involves the interaction between the sun, wind, and earth. During the day, solar heating produces thermal instability, which enhances the convective mixing of high momentum winds from the upper levels of the atmosphere to the s...

  10. Exercise, physical activity, and exertion over the business cycle.

    PubMed

    Colman, Gregory; Dave, Dhaval

    2013-09-01

    Shifts in time and income constraints over economic expansions and contractions would be expected to affect individuals' behaviors. We explore the impact of the business cycle on individuals' exercise, time use, and total physical exertion, utilizing information on 112,000 individual records from the 2003-2010 American Time Use Surveys. In doing so, we test a key causal link that has been hypothesized in the relation between unemployment and health, but not heretofore assessed. Using more precise measures of exercise (and other activities) than previous studies, we find that as work-time decreases during a recession, recreational exercise, TV-watching, sleeping, childcare, and housework increase. This, however, does not compensate for the decrease in work-related exertion due to job-loss, and total physical exertion declines. These effects are strongest among low-educated men, which is validating given that employment in the Great Recession has declined most within manufacturing, mining, and construction. We also find evidence of intra-household spillover effects, wherein individuals respond to shifts in spousal employment conditional on their own labor supply. The decrease in total physical activity during recessions is especially problematic for vulnerable populations concentrated in boom-and-bust industries, and may have longer-term effects on obesity and related health outcomes. PMID:23906116

  11. Assessment of downscaled current and future projections of diurnal rainfall patterns for the Himalaya

    NASA Astrophysics Data System (ADS)

    Bhatt, B. C.; Sobolowski, Stefan; King, Martin P.

    2014-11-01

    In this study we investigate the diurnal precipitation cycle in high-resolution regional climate simulations for present (2000-2010) and future time periods (2030-2040 and 2040-2050) over subregions of the Himalayas. The future periods are simulated under a high-emission scenario, Representative Concentration Pathway 8.5 (RCP8.5) in order to maximize any projected externally driven precipitation signal. For present climate, 4-hourly simulated precipitation is first evaluated against observations to establish model credibility. The diurnal cycle, which is typically characterized by a bimodal structure with primary (secondary) maxima in nighttime (afternoon), is reasonably well represented in the present, giving us confidence when assessing potential future changes. The timing of the precipitation maxima and minima is found to match the observed timings well in the diurnal cycle. In general, the Weather Research and Forecasting model captures the principal shape of the diurnal cycle observed over all the subregions. Under projected future conditions, no significant changes in the diurnal cycle occur. The results suggest modest changes in diurnal precipitation under RCP8.5 emission scenario, as evidenced by an increase in afternoon precipitation around the Himalayas. Although the projected future changes of precipitation presented in this article are within of the expected range of precipitation changes caution must be exercised when interpreting single-model experiments.

  12. Long-Range Solar Activity Predictions: A Reprieve from Cycle #24's Activity

    NASA Technical Reports Server (NTRS)

    Richon, K.; Schatten, K.

    2003-01-01

    We discuss the field of long-range solar activity predictions and provide an outlook into future solar activity. Orbital predictions for satellites in Low Earth Orbit (LEO) depend strongly on exospheric densities. Solar activity forecasting is important in this regard, as the solar ultra-violet (UV) and extreme ultraviolet (EUV) radiations inflate the upper atmospheric layers of the Earth, forming the exosphere in which satellites orbit. Rather than concentrate on statistical, or numerical methods, we utilize a class of techniques (precursor methods) which is founded in physical theory. The geomagnetic precursor method was originally developed by the Russian geophysicist, Ohl, using geomagnetic observations to predict future solar activity. It was later extended to solar observations, and placed within the context of physical theory, namely the workings of the Sun s Babcock dynamo. We later expanded the prediction methods with a SOlar Dynamo Amplitude (SODA) index. The SODA index is a measure of the buried solar magnetic flux, using toroidal and poloidal field components. It allows one to predict future solar activity during any phase of the solar cycle, whereas previously, one was restricted to making predictions only at solar minimum. We are encouraged that solar cycle #23's behavior fell closely along our predicted curve, peaking near 192, comparable to the Schatten, Myers and Sofia (1996) forecast of 182+/-30. Cycle #23 extends from 1996 through approximately 2006 or 2007, with cycle #24 starting thereafter. We discuss the current forecast of solar cycle #24, (2006-2016), with a predicted smoothed F10.7 radio flux of 142+/-28 (1-sigma errors). This, we believe, represents a reprieve, in terms of reduced fuel costs, etc., for new satellites to be launched or old satellites (requiring reboosting) which have been placed in LEO. By monitoring the Sun s most deeply rooted magnetic fields; long-range solar activity can be predicted. Although a degree of uncertainty

  13. A Krebs Cycle Component Limits Caspase Activation Rate through Mitochondrial Surface Restriction of CRL Activation.

    PubMed

    Aram, Lior; Braun, Tslil; Braverman, Carmel; Kaplan, Yosef; Ravid, Liat; Levin-Zaidman, Smadar; Arama, Eli

    2016-04-01

    How cells avoid excessive caspase activity and unwanted cell death during apoptotic caspase-mediated removal of large cellular structures is poorly understood. We investigate caspase-mediated extrusion of spermatid cytoplasmic contents in Drosophila during spermatid individualization. We show that a Krebs cycle component, the ATP-specific form of the succinyl-CoA synthetase β subunit (A-Sβ), binds to and activates the Cullin-3-based ubiquitin ligase (CRL3) complex required for caspase activation in spermatids. In vitro and in vivo evidence suggests that this interaction occurs on the mitochondrial surface, thereby limiting the source of CRL3 complex activation to the vicinity of this organelle and reducing the potential rate of caspase activation by at least 60%. Domain swapping between A-Sβ and the GTP-specific SCSβ (G-Sβ), which functions redundantly in the Krebs cycle, show that the metabolic and structural roles of A-Sβ in spermatids can be uncoupled, highlighting a moonlighting function of this Krebs cycle component in CRL activation. PMID:27052834

  14. The circadian oscillator in Synechococcus elongatus controls metabolite partitioning during diurnal growth

    PubMed Central

    Diamond, Spencer; Jun, Darae; Rubin, Benjamin E.; Golden, Susan S.

    2015-01-01

    Synechococcus elongatus PCC 7942 is a genetically tractable model cyanobacterium that has been engineered to produce industrially relevant biomolecules and is the best-studied model for a prokaryotic circadian clock. However, the organism is commonly grown in continuous light in the laboratory, and data on metabolic processes under diurnal conditions are lacking. Moreover, the influence of the circadian clock on diurnal metabolism has been investigated only briefly. Here, we demonstrate that the circadian oscillator influences rhythms of metabolism during diurnal growth, even though light–dark cycles can drive metabolic rhythms independently. Moreover, the phenotype associated with loss of the core oscillator protein, KaiC, is distinct from that caused by absence of the circadian output transcriptional regulator, RpaA (regulator of phycobilisome-associated A). Although RpaA activity is important for carbon degradation at night, KaiC is dispensable for those processes. Untargeted metabolomics analysis and glycogen kinetics suggest that functional KaiC is important for metabolite partitioning in the morning. Additionally, output from the oscillator functions to inhibit RpaA activity in the morning, and kaiC-null strains expressing a mutant KaiC phosphomimetic, KaiC-pST, in which the oscillator is locked in the most active output state, phenocopies a ΔrpaA strain. Inhibition of RpaA by the oscillator in the morning suppresses metabolic processes that normally are active at night, and kaiC-null strains show indications of oxidative pentose phosphate pathway activation as well as increased abundance of primary metabolites. Inhibitory clock output may serve to allow secondary metabolite biosynthesis in the morning, and some metabolites resulting from these processes may feed back to reinforce clock timing. PMID:25825710

  15. A Summary of Closed Brayton Cycle Development Activities at NASA

    NASA Technical Reports Server (NTRS)

    Mason, Lee S.

    2009-01-01

    NASA has been involved in the development of Closed Brayton Cycle (CBC) power conversion technology since the 1960's. CBC systems can be coupled to reactor, isotope, or solar heat sources and offer the potential for high efficiency, long life, and scalability to high power. In the 1960's and 1970's, NASA and industry developed the 10 kW Brayton Rotating Unit (BRU) and the 2 kW mini-BRU demonstrating technical feasibility and performance, In the 1980's, a 25 kW CBC Solar Dynamic (SD) power system option was developed for Space Station Freedom and the technology was demonstrated in the 1990's as part of the 2 kW SO Ground Test Demonstration (GTD). Since the early 2000's, NASA has been pursuing CBC technology for space reactor applications. Before it was cancelled, the Jupiter Icy Moons Orbiter (HMO) mission was considering a 100 kWclass CBC system coupled to a gas-cooled fission reactor. Currently, CBC technology is being explored for Fission Surface Power (FSP) systems to provide base power on the moon and Mars. These recent activities have resulted in several CBC-related technology development projects including a 50 kW Alternator Test Unit, a 20 kW Dual Brayton Test Loop, a 2 kW Direct Drive Gas Brayton Test Loop, and a 12 kW FSP Power Conversion Unit design.

  16. Quantifying promoter activity during the developmental cycle of Chlamydia trachomatis

    PubMed Central

    Cong, Yanguang; Gao, Leiqiong; Zhang, Yan; Xian, Yuqi; Hua, Ziyu; Elaasar, Hiba; Shen, Li

    2016-01-01

    Chlamydia trachomatis is an important human pathogen that undergoes a characteristic development cycle correlating with stage-specific gene expression profiles. Taking advantage of recent developments in the genetic transformation in C. trachomatis, we constructed a versatile green fluorescent protein (GFP) reporter system to study the development-dependent function of C. trachomatis promoters in an attempt to elucidate the mechanism that controls C. trachomatis adaptability. We validated the use of the GFP reporter system by visualizing the activity of an early euo gene promoter. Additionally, we uncovered a new ompA promoter, which we named P3, utilizing the GFP reporter system combined with 5′ rapid amplification of cDNA ends (RACE), in vitro transcription assays, real-time quantitative RT-PCR (RT-qPCR), and flow cytometry. Mutagenesis of the P3 region verifies that P3 is a new class of C. trachomatis σ66-dependent promoter, which requires an extended −10 TGn motif for transcription. These results corroborate complex developmentally controlled ompA expression in C. trachomatis. The exploitation of genetically labeled C. trachomatis organisms with P3-driven GFP allows for the observation of changes in ompA expression in response to developmental signals. The results of this study could be used to complement previous findings and to advance understanding of C. trachomatis genetic expression. PMID:27263495

  17. Quantifying promoter activity during the developmental cycle of Chlamydia trachomatis.

    PubMed

    Cong, Yanguang; Gao, Leiqiong; Zhang, Yan; Xian, Yuqi; Hua, Ziyu; Elaasar, Hiba; Shen, Li

    2016-01-01

    Chlamydia trachomatis is an important human pathogen that undergoes a characteristic development cycle correlating with stage-specific gene expression profiles. Taking advantage of recent developments in the genetic transformation in C. trachomatis, we constructed a versatile green fluorescent protein (GFP) reporter system to study the development-dependent function of C. trachomatis promoters in an attempt to elucidate the mechanism that controls C. trachomatis adaptability. We validated the use of the GFP reporter system by visualizing the activity of an early euo gene promoter. Additionally, we uncovered a new ompA promoter, which we named P3, utilizing the GFP reporter system combined with 5' rapid amplification of cDNA ends (RACE), in vitro transcription assays, real-time quantitative RT-PCR (RT-qPCR), and flow cytometry. Mutagenesis of the P3 region verifies that P3 is a new class of C. trachomatis σ(66)-dependent promoter, which requires an extended -10 TGn motif for transcription. These results corroborate complex developmentally controlled ompA expression in C. trachomatis. The exploitation of genetically labeled C. trachomatis organisms with P3-driven GFP allows for the observation of changes in ompA expression in response to developmental signals. The results of this study could be used to complement previous findings and to advance understanding of C. trachomatis genetic expression. PMID:27263495

  18. A Solar Cycle Dependence of Nonlinearity in Magnetospheric Activity

    SciTech Connect

    Johnson, Jay R; Wing, Simon

    2005-03-08

    The nonlinear dependencies inherent to the historical K(sub)p data stream (1932-2003) are examined using mutual information and cumulant based cost as discriminating statistics. The discriminating statistics are compared with surrogate data streams that are constructed using the corrected amplitude adjustment Fourier transform (CAAFT) method and capture the linear properties of the original K(sub)p data. Differences are regularly seen in the discriminating statistics a few years prior to solar minima, while no differences are apparent at the time of solar maximum. These results suggest that the dynamics of the magnetosphere tend to be more linear at solar maximum than at solar minimum. The strong nonlinear dependencies tend to peak on a timescale around 40-50 hours and are statistically significant up to one week. Because the solar wind driver variables, VB(sub)s and dynamical pressure exhibit a much shorter decorrelation time for nonlinearities, the results seem to indicate that the nonlinearity is related to internal magnetospheric dynamics. Moreover, the timescales for the nonlinearity seem to be on the same order as that for storm/ring current relaxation. We suggest that the strong solar wind driving that occurs around solar maximum dominates the magnetospheric dynamics suppressing the internal magnetospheric nonlinearity. On the other hand, in the descending phase of the solar cycle just prior to solar minimum, when magnetospheric activity is weaker, the dynamics exhibit a significant nonlinear internal magnetospheric response that may be related to increased solar wind speed.

  19. Diurnal variation in the performance of rapid response systems: the role of critical care services-a review article.

    PubMed

    Sundararajan, Krishnaswamy; Flabouris, Arthas; Thompson, Campbell

    2016-01-01

    The type of medical review before an adverse event influences patient outcome. Delays in the up-transfer of patients requiring intensive care are associated with higher mortality rates. Timely detection and response to a deteriorating patient constitute an important function of the rapid response system (RRS). The activation of the RRS for at-risk patients constitutes the system's afferent limb. Afferent limb failure (ALF), an important performance measure of rapid response systems, constitutes a failure to activate a rapid response team (RRT) despite criteria for calling an RRT. There are diurnal variations in hospital staffing levels, the performance of rapid response systems and patient outcomes. Fewer ward-based nursing staff at night may contribute to ALF. The diurnal variability in RRS activity is greater in unmonitored units than it is in monitored units for events that should result in a call for an RRT. RRT events include a significant abnormality in either the pulse rate, blood pressure, conscious state or respiratory rate. There is also diurnal variation in RRT summoning rates, with most activations occurring during the day. The reasons for this variation are mostly speculative, but the failure of the afferent limb of RRT activation, particularly at night, may be a factor. The term "circadian variation/rhythm" applies to physiological variations over a 24-h cycle. In contrast, diurnal variation applies more accurately to extrinsic systems. Circadian rhythm has been demonstrated in a multitude of bodily functions and disease states. For example, there is an association between disrupted circadian rhythms and abnormal vital parameters such as anomalous blood pressure, irregular pulse rate, aberrant endothelial function, myocardial infarction, stroke, sleep-disordered breathing and its long-term consequences of hypertension, heart failure and cognitive impairment. Therefore, diurnal variation in patient outcomes may be extrinsic, and more easily modifiable

  20. Solar Activity in Cycle 24 - What do Acoustic Oscillations tell us?

    NASA Astrophysics Data System (ADS)

    Jain, Kiran; Tripathy, Sushant; Simoniello, Rosaria; Hill, Frank

    2016-05-01

    Solar Cycle 24 is the weakest cycle in modern era of space- and ground-based observations. The number of sunspots visible on solar disk and other measures of magnetic activity have significantly decreased from the last cycle. It was also preceeded by an extended phase of low activity, a period that raised questions on our understanding of the solar activity cycle and its origin. This unusual behavior was not only limited to the visible features in Sun's atmosphere, the helioseismic observations also revealed peculiar behavior in the interior. It was suggested that the changes in magnetic activity were confined to shallower layers only, as a result low-degree mode frequencies were found to be anti-correlated with solar activity. Here we present results on the progression of Cycle 24 by analyzing the uninterrupted helioseismic data from GONG and SDO/HMI, and discuss differences and similarity between cycles 23 and 24 in relation to the solar activity.

  1. Unique Regulation of the Melatonin Synthetic Pathway in the Retina of Diurnal Female Arvicanthis ansorgei (Rodentia).

    PubMed

    Gianesini, Coralie; Clesse, Daniel; Tosini, Gianluca; Hicks, David; Laurent, Virginie

    2015-09-01

    Knowledge about melatonin synthesis and its potential roles within the retina remains fragmented, especially in mammals where studies have focused on the penultimate enzyme of melatonin synthesis arylalkylamine N-acetyltransferase (AA-NAT), whereas the final enzyme necessary for melatonin production is hydroxyindole-O-methytransferase (HIOMT). We explored multiple parameters of the melatonin synthetic pathway in the cone-rich retina of a diurnal rodent, Arvicanthis ansorgei, cones being previously implicated as probable reservoirs of melatonin production. We analyzed the temporal and spatial expression of Aa-nat mRNA and AA-NAT protein and enzymatic activity of AA-NAT, HIOMT, as well as the melatonin receptor type 1 and melatonin itself. We report that Aa-nat mRNA was localized principally to cones and ganglion cells (retinal ganglion cell [RGC]) with opposing cyclic expression, being maximal in cones during the night, and maximal in RGC in the daytime. AA-NAT protein was also immunolocalized to these same populations, and was present and active throughout the 24-hour period. HIOMT immunolocalization mirrored that of AA-NAT, but expression levels and activity were extremely low and remained uniform throughout the 24-hour period. MT1 showed a complementary expression pattern to the synthetic enzymes, present in rod photoreceptors, some inner retinal neurons and RGC. Surprisingly, melatonin levels were consistently low throughout the day/night cycle, in accordance with the low activity levels of HIOMT. These data demonstrate that the melatonin synthetic pathway in a diurnal rodent differs from that described for other tissues and species (nocturnal and diurnal), the contrasting phase expression in photoreceptors and RGC, suggesting distinct roles in these populations. PMID:26153723

  2. Observations of SST diurnal variability in the South China Sea

    NASA Astrophysics Data System (ADS)

    Tu, Qianguang; Pan, Delu; Hao, Zengzhou; Chen, Jianyu

    2015-10-01

    In this study, a 3-hourly time resolution gap free sea surface temperature (SST) analysis is generated to resolve the diurnal cycle in the South China Sea (SCS, 0°-25°N, 100°-125°E).It takes advantage of hourly geostationary satellite MTSAT observations and combines three infrared and two microwave polar satellite observations at different local times. First, all the data are classified into eight SST datasets at 3 hour intervals and then remapped to 0.05°resolution grids. A series of critical quality control is done to remove the outliers.Then bias adjustment is applied to the polar satellite observations with reference to the MTSAT data. Finally, the six satellites SST data are blended by using the optimal interpolated algorithm. The 3-hourly blended SST is compared against buoy measurements. It shows a good agreement that the biases do not exceed 0.2 °C and root mean square errors range from 0.5 to 0.65 °C. A typical diurnal cycle similar to sine wave is observed. The minimum SST occurs at around 0600h and warming peak occurring between 1300h and 1500h local solar time and then decrease in the late afternoon, tapering off at night on March 13, 2008 for example. The frequency of diurnal warming events derived from four years of the blended SST provides solid statistics to investigate the seasonal and spatial distributions of the diurnal warming in the SCS. The sea surface diurnal warming tends to appear more easily in spring, especially in the coastal regions than other seasons and the central regions.

  3. Diurnal patterns of productivity of arbuscular mycorrhizal fungi revealed with the Soil Ecosystem Observatory

    PubMed Central

    Hernandez, Rebecca R; Allen, Michael F

    2013-01-01

    Arbuscular mycorrhizal (AM) fungi are the most abundant plant symbiont and a major pathway of carbon sequestration in soils. However, their basic biology, including their activity throughout a 24-h day : night cycle, remains unknown. We employed the in situ Soil Ecosystem Observatory to quantify the rates of diurnal growth, dieback and net productivity of extra-radical AM fungi. AM fungal hyphae showed significantly different rates of growth and dieback over a period of 24 h and paralleled the circadian-driven photosynthetic oscillations observed in plants. The greatest rates (and incidences) of growth and dieback occurred between noon and 18:00 h. Growth and dieback events often occurred simultaneously and were tightly coupled with soil temperature and moisture, suggesting a rapid acclimation of the external phase of AM fungi to the immediate environment. Changes in the environmental conditions and variability of the mycorrhizosphere may alter the diurnal patterns of productivity of AM fungi, thereby modifying soil carbon sequestration, nutrient cycling and host plant success. PMID:23844990

  4. Proton activity of the Sun in current solar cycle 24

    NASA Astrophysics Data System (ADS)

    Li, Chuan; Miroshnichenko, Leonty I.; Fang, Cheng

    2015-07-01

    We present a study of seven large solar proton events in the current solar cycle 24 (from 2009 January up to the current date). They were recorded by the GOES spacecraft with the highest proton fluxes being over 200 pfu for energies >10 MeV. In situ particle measurements show that: (1) The profiles of the proton fluxes are highly dependent on the locations of their solar sources, namely flares or coronal mass ejections (CMEs), which confirms the “heliolongitude rules” associated with solar energetic particle fluxes; (2) The solar particle release (SPR) times fall in the decay phase of the flare emission, and are in accordance with the times when the CMEs travel to an average height of 7.9 solar radii; and (3) The time differences between the SPR and the flare peak are also dependent on the locations of the solar active regions. The results tend to support the scenario of proton acceleration by the CME-driven shock, even though there exists a possibility of particle acceleration at the flare site, with subsequent perpendicular diffusion of accelerated particles in the interplanetary magnetic field. We derive the integral time-of-maximum spectra of solar protons in two forms: a single power-law distribution and a power law roll-over with an exponential tail. It is found that the unique ground level enhancement that occurred in the event on 2012 May 17 displays the hardest spectrum and the largest roll-over energy which may explain why this event could extend to relativistic energies. Supported by the National Natural Science Foundation of China.

  5. Monitoring seasonal and diurnal changes in photosynthetic pigments with automated PRI and NDVI sensors

    NASA Astrophysics Data System (ADS)

    Gamon, J. A.; Kovalchuck, O.; Wong, C. Y. S.; Harris, A.; Garrity, S. R.

    2015-07-01

    The vegetation indices normalized difference vegetation index (NDVI) and photochemical reflectance index (PRI) provide indicators of pigmentation and photosynthetic activity that can be used to model photosynthesis from remote sensing with the light-use-efficiency model. To help develop and validate this approach, reliable proximal NDVI and PRI sensors have been needed. We tested new NDVI and PRI sensors, "spectral reflectance sensors" (SRS sensors; recently developed by Decagon Devices, during spring activation of photosynthetic activity in evergreen and deciduous stands. We also evaluated two methods of sensor cross-calibration - one that considered sky conditions (cloud cover) at midday only, and another that also considered diurnal sun angle effects. Cross-calibration clearly affected sensor agreement with independent measurements, with the best method dependent upon the study aim and time frame (seasonal vs. diurnal). The seasonal patterns of NDVI and PRI differed for evergreen and deciduous species, demonstrating the complementary nature of these two indices. Over the spring season, PRI was most strongly influenced by changing chlorophyll : carotenoid pool sizes, while over the diurnal timescale, PRI was most affected by the xanthophyll cycle epoxidation state. This finding demonstrates that the SRS PRI sensors can resolve different processes affecting PRI over different timescales. The advent of small, inexpensive, automated PRI and NDVI sensors offers new ways to explore environmental and physiological constraints on photosynthesis, and may be particularly well suited for use at flux tower sites. Wider application of automated sensors could lead to improved integration of flux and remote sensing approaches for studying photosynthetic carbon uptake, and could help define the concept of contrasting vegetation optical types.

  6. Monitoring seasonal and diurnal changes in photosynthetic pigments with automated PRI and NDVI sensors

    NASA Astrophysics Data System (ADS)

    Gamon, J. A.; Kovalchuk, O.; Wong, C. Y. S.; Harris, A.; Garrity, S. R.

    2015-02-01

    The vegetation indices normalized difference vegetation index (NDVI) and photochemical reflectance index (PRI) provide indicators of pigmentation and photosynthetic activity that can be used to model photosynthesis from remote sensing with the light-use efficiency model. To help develop and validate this approach, reliable proximal NDVI and PRI sensors have been needed. We tested new NDVI and PRI sensors, "SRS" sensors recently developed by Decagon Devices, during spring activation of photosynthetic activity in evergreen and deciduous stands. We also evaluated two methods of sensor cross-calibration, one that considered sky conditions (cloud cover) at midday only, and the other that also considered diurnal sun angle effects. Cross-calibration clearly affected sensor agreement with independent measurements, with the best method dependent upon the study aim and time frame (seasonal vs. diurnal). The seasonal patterns of NDVI and PRI differed for evergreen and deciduous species, demonstrating the complementary nature of these two indices. Over the spring season, PRI was most strongly influenced by changing chlorophyll : carotenoid pool sizes, while over the diurnal time scale PRI was most affected by the xanthophyll cycle epoxidation state. This finding demonstrates that the SRS PRI sensors can resolve different processes affecting PRI over different time scales. The advent of small, inexpensive, automated PRI and NDVI sensors offers new ways to explore environmental and physiological constraints on photosynthesis, and may be particularly well-suited for use at flux tower sites. Wider application of automated sensors could lead to improved integration of flux and remote sensing approaches to studying photosynthetic carbon uptake, and could help define the concept of contrasting vegetation optical types.

  7. Diurnal Variability of Tropical Rainfall Retrieved from Combined GOES and TRMM Satellite Information.

    NASA Astrophysics Data System (ADS)

    Sorooshian, S.; Gao, X.; Hsu, K.; Maddox, R. A.; Hong, Y.; Gupta, H. V.; Imam, B.

    2002-05-01

    Recent progress in satellite remote-sensing techniques for precipitation estimation, along with more accurate tropical rainfall measurements from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and precipitation radar (PR) instruments, have made it possible to monitor tropical rainfall diurnal patterns and their intensities from satellite information. One year (August 1998-July 1999) of tropical rainfall estimates from the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) system were used to produce monthly means of rainfall diurnal cycles at hourly and 1° × 1° scales over a domain (30°S-30°N, 80°E-10°W) from the Americas across the Pacific Ocean to Australia and eastern Asia.The results demonstrate pronounced diurnal variability of tropical rainfall intensity at synoptic and regional scales. Seasonal signals of diurnal rainfall are presented over the large domain of the tropical Pacific Ocean, especially over the ITCZ and South Pacific convergence zone (SPCZ) and neighboring continents. The regional patterns of tropical rainfall diurnal cycles are specified in the Amazon, Mexico, the Caribbean Sea, Calcutta, Bay of Bengal, Malaysia, and northern Australia. Limited validations for the results include comparisons of 1) the PERSIANN-derived diurnal cycle of rainfall at Rondonia, Brazil, with that derived from the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) radar data; 2) the PERSIANN diurnal cycle of rainfall over the western Pacific Ocean with that derived from the data of the optical rain gauges mounted on the TOGA-moored buoys; and 3) the monthly accumulations of rainfall samples from the orbital TMI and PR surface rainfall with the accumulations of concurrent PERSIANN estimates. These comparisons indicate that the PERSIANN-derived diurnal patterns at the selected resolutions produce estimates that are similar in magnitude and phase.

  8. Arvicanthis ansorgei, a Novel Model for the Study of Sleep and Waking in Diurnal Rodents

    PubMed Central

    Hubbard, Jeffrey; Ruppert, Elisabeth; Calvel, Laurent; Robin-Choteau, Ludivine; Gropp, Claire-Marie; Allemann, Caroline; Reibel, Sophie; Sage-Ciocca, Dominique; Bourgin, Patrice

    2015-01-01

    Study Objectives: Sleep neurobiology studies use nocturnal species, mainly rats and mice. However, because their daily sleep/wake organization is inverted as compared to humans, a diurnal model for sleep studies is needed. To fill this gap, we phenotyped sleep and waking in Arvicanthis ansorgei, a diurnal rodent widely used for the study of circadian rhythms. Design: Video-electroencephalogram (EEG), electromyogram (EMG), and electrooculogram (EOG) recordings. Setting: Rodent sleep laboratory. Participants: Fourteen male Arvicanthis ansorgei, aged 3 mo. Interventions: 12 h light (L):12 h dark (D) baseline condition, 24-h constant darkness, 6-h sleep deprivation. Measurements and Results: Wake and rapid eye movement (REM) sleep showed similar electrophysiological characteristics as nocturnal rodents. On average, animals spent 12.9 h ± 0.4 awake per 24-h cycle, of which 6.88 h ± 0.3 was during the light period. NREM sleep accounted for 9.63 h ± 0.4, which of 5.13 h ± 0.2 during dark period, and REM sleep for 89.9 min ± 6.7, which of 52.8 min ± 4.4 during dark period. The time-course of sleep and waking across the 12 h light:12 h dark was overall inverted to that observed in rats or mice, though with larger amounts of crepuscular activity at light and dark transitions. A dominant crepuscular regulation of sleep and waking persisted under constant darkness, showing the lack of a strong circadian drive in the absence of clock reinforcement by external cues, such as a running wheel. Conservation of the homeostatic regulation was confirmed with the observation of higher delta power following sustained waking periods and a 6-h sleep deprivation, with subsequent decrease during recovery sleep. Conclusions: Arvicanthis ansorgei is a valid diurnal rodent model for studying the regulatory mechanisms of sleep and so represents a valuable tool for further understanding the nocturnality/diurnality switch. Citation: Hubbard J, Ruppert E, Calvel L, Robin-Choteau L, Gropp CM

  9. Altered Electroencephalographic Activity Associated with Changes in the Sleep-Wakefulness Cycle of C57BL/6J Mice in Response to a Photoperiod Shortening

    PubMed Central

    Rozov, Stanislav V.; Zant, Janneke C.; Gurevicius, Kestutis; Porkka-Heiskanen, Tarja; Panula, Pertti

    2016-01-01

    Aim: Under natural conditions diurnal rhythms of biological processes of the organism are synchronized with each other and to the environmental changes by means of the circadian system. Disturbances of the latter affect hormonal levels, sleep-wakefulness cycle and cognitive performance. To study mechanisms of such perturbations animal models subjected to artificial photoperiods are often used. The goal of current study was to understand the effects of circadian rhythm disruption, caused by a short light-dark cycle regime, on activity of the cerebral cortex in rodents. Methods: We used electroencephalogram to assess the distribution of vigilance states, perform spectral analysis, and estimate the homeostatic sleep drive. In addition, we analyzed spontaneous locomotion of C57BL/6J mice under symmetric, 22-, 21-, and 20-h-long light–dark cycles using video recording and tracking methods. Results and Conclusions: We found that shortening of photoperiod caused a significant increase of slow wave activity during non-rapid eye movement sleep suggesting an elevation of sleep pressure under such conditions. While the rhythm of spontaneous locomotion was completely entrained by all light–dark cycles tested, periodic changes in the power of the θ- and γ-frequency ranges during wakefulness gradually disappeared under 22- and 21-h-long light–dark cycles. This was associated with a significant increase in the θ–γ phase-amplitude coupling during wakefulness. Our results thus provide deeper understanding of the mechanisms underlying the impairment of learning and memory retention, which is associated with disturbed circadian regulation.

  10. Diurnality, nocturnality, and the evolution of primate visual systems.

    PubMed

    Ankel-Simons, F; Rasmussen, D T

    2008-01-01

    Much of the recent research on the evolution of primate visual systems has assumed that a minimum number of shifts have occurred in circadian activity patterns over the course of primate evolution. The evolutionary origins of key higher taxonomic groups have been interpreted by some researchers as a consequence of a rare shift from nocturnality to diurnality (e.g., Anthropoidea) or from diurnality to nocturnality (e.g., Tarsiidae). Interpreting the evolution of primate visual systems with an ecological approach without parsimony constraints suggests that the evolutionary transitions in activity pattern are more common than what would be allowed by parsimony models, and that such transitions are probably less important in the origin of higher level taxa. The analysis of 17 communities of primates distributed widely around the world and through geological time shows that primate communities consistently contain both nocturnal and diurnal forms, regardless of the taxonomic sources of the communities. This suggests that primates in a community will adapt their circadian pattern to fill empty diurnal or nocturnal niches. Several evolutionary transitions from one pattern to the other within narrow taxonomic groups are solidly documented, and these cases probably represent a small fraction of such transitions throughout the Cenozoic. One or more switches have been documented among platyrrhine monkeys, Malagasy prosimians, Eocene omomyids, Eocene adapoids, and early African anthropoids, with inconclusive but suggestive data within tarsiids. The interpretation of living and extinct primates as fitting into one of two diarhythmic categories is itself problematic, because many extant primates show significant behavioral activity both nocturnally and diurnally. Parsimony models routinely interpret ancestral primates to have been nocturnal, but analyses of morphological and genetic data indicate that they may have been diurnal, or that early primate radiations were likely to

  11. PARALLEL EVALUATION OF CONSTANT AND DIURNAL FLOW TREATMENT SYSTEMS

    EPA Science Inventory

    Pilot plant studies were performed to evaluate the effects of an imposed diurnal flow pattern on a conventional activated sludge treatment plant. These results were compared against data generated on a similar system treating a constant flow. Effects on primary clarifier and fina...

  12. Life cycle assessment of active and passive groundwater remediation technologies

    NASA Astrophysics Data System (ADS)

    Bayer, Peter; Finkel, Michael

    2006-02-01

    Groundwater remediation technologies, such as pump-and-treat (PTS) and funnel-and-gate systems (FGS), aim at reducing locally appearing contaminations. Therefore, these methodologies are basically evaluated with respect to their capability to yield local improvements of an environmental situation, commonly neglecting that their application is also associated with secondary impacts. Life cycle assessment (LCA) represents a widely accepted method of assessing the environmental aspects and potential impacts related to a product, process or service. This study presents the set-up of a LCA framework in order to compare the secondary impacts caused by two conceptually different technologies at the site of a former manufactured gas plant in the city of Karlsruhe, Germany. As a FGS is already operating at this site, a hypothetical PTS of the same functionality is adopted. During the LCA, the remediation systems are evaluated by focusing on the main technical elements and their significance with respect to resource depletion and potential adverse effects on ecological quality, as well as on human health. Seven impact categories are distinguished to address a broad spectrum of possible environmental loads. A main point of discussion is the reliability of technical assumptions and performance predictions for the future. It is obvious that a high uncertainty exists when estimating impact specific indicator values over operation times of decades. An uncertainty analysis is conducted to include the imprecision of the underlying emission and consumption data and a scenario analysis is utilised to contrast various possible technological variants. Though the results of the study are highly site-specific, a generalised relative evaluation of potential impacts and their main sources is the principle objective rather than a discussion of the calculated absolute impacts. A crucial finding that can be applied to any other site is the central role of steel, which particularly derogates

  13. Staphylococcal Enterotoxin O Exhibits Cell Cycle Modulating Activity

    PubMed Central

    Hodille, Elisabeth; Alekseeva, Ludmila; Berkova, Nadia; Serrier, Asma; Badiou, Cedric; Gilquin, Benoit; Brun, Virginie; Vandenesch, François; Terman, David S.; Lina, Gerard

    2016-01-01

    Maintenance of an intact epithelial barrier constitutes a pivotal defense mechanism against infections. Staphylococcus aureus is a versatile pathogen that produces multiple factors including exotoxins that promote tissue alterations. The aim of the present study is to investigate the cytopathic effect of staphylococcal exotoxins SEA, SEG, SEI, SElM, SElN and SElO on the cell cycle of various human cell lines. Among all tested exotoxins only SEIO inhibited the proliferation of a broad panel of human tumor cell lines in vitro. Evaluation of a LDH release and a DNA fragmentation of host cells exposed to SEIO revealed that the toxin does not induce necrosis or apoptosis. Analysis of the DNA content of tumor cells synchronized by serum starvation after exposure to SEIO showed G0/G1 cell cycle delay. The cell cycle modulating feature of SEIO was confirmed by the flow cytometry analysis of synchronized cells exposed to supernatants of isogenic S. aureus strains wherein only supernatant of the SElO producing strain induced G0/G1 phase delay. The results of yeast-two-hybrid analysis indicated that SEIO’s potential partner is cullin-3, involved in the transition from G1 to S phase. In conclusion, we provide evidence that SEIO inhibits cell proliferation without inducing cell death, by delaying host cell entry into the G0/G1 phase of the cell cycle. We speculate that this unique cell cycle modulating feature allows SEIO producing bacteria to gain advantage by arresting the cell cycle of target cells as part of a broader invasive strategy. PMID:27148168

  14. Staphylococcal Enterotoxin O Exhibits Cell Cycle Modulating Activity.

    PubMed

    Hodille, Elisabeth; Alekseeva, Ludmila; Berkova, Nadia; Serrier, Asma; Badiou, Cedric; Gilquin, Benoit; Brun, Virginie; Vandenesch, François; Terman, David S; Lina, Gerard

    2016-01-01

    Maintenance of an intact epithelial barrier constitutes a pivotal defense mechanism against infections. Staphylococcus aureus is a versatile pathogen that produces multiple factors including exotoxins that promote tissue alterations. The aim of the present study is to investigate the cytopathic effect of staphylococcal exotoxins SEA, SEG, SEI, SElM, SElN and SElO on the cell cycle of various human cell lines. Among all tested exotoxins only SEIO inhibited the proliferation of a broad panel of human tumor cell lines in vitro. Evaluation of a LDH release and a DNA fragmentation of host cells exposed to SEIO revealed that the toxin does not induce necrosis or apoptosis. Analysis of the DNA content of tumor cells synchronized by serum starvation after exposure to SEIO showed G0/G1 cell cycle delay. The cell cycle modulating feature of SEIO was confirmed by the flow cytometry analysis of synchronized cells exposed to supernatants of isogenic S. aureus strains wherein only supernatant of the SElO producing strain induced G0/G1 phase delay. The results of yeast-two-hybrid analysis indicated that SEIO's potential partner is cullin-3, involved in the transition from G1 to S phase. In conclusion, we provide evidence that SEIO inhibits cell proliferation without inducing cell death, by delaying host cell entry into the G0/G1 phase of the cell cycle. We speculate that this unique cell cycle modulating feature allows SEIO producing bacteria to gain advantage by arresting the cell cycle of target cells as part of a broader invasive strategy. PMID:27148168

  15. Sugars and circadian regulation make major contributions to the global regulation of diurnal gene expression in Arabidopsis.

    PubMed

    Bläsing, Oliver E; Gibon, Yves; Günther, Manuela; Höhne, Melanie; Morcuende, Rosa; Osuna, Daniel; Thimm, Oliver; Usadel, Björn; Scheible, Wolf-Rüdiger; Stitt, Mark

    2005-12-01

    The diurnal cycle strongly influences many plant metabolic and physiological processes. Arabidopsis thaliana rosettes were harvested six times during 12-h-light/12-h-dark treatments to investigate changes in gene expression using ATH1 arrays. Diagnostic gene sets were identified from published or in-house expression profiles of the response to light, sugar, nitrogen, and water deficit in seedlings and 4 h of darkness or illumination at ambient or compensation point [CO(2)]. Many sugar-responsive genes showed large diurnal expression changes, whose timing matched that of the diurnal changes of sugars. A set of circadian-regulated genes also showed large diurnal changes in expression. Comparison of published results from a free-running cycle with the diurnal changes in Columbia-0 (Col-0) and the starchless phosphoglucomutase (pgm) mutant indicated that sugars modify the expression of up to half of the clock-regulated genes. Principle component analysis identified genes that make large contributions to diurnal changes and confirmed that sugar and circadian regulation are the major inputs in Col-0 but that sugars dominate the response in pgm. Most of the changes in pgm are triggered by low sugar levels during the night rather than high levels in the light, highlighting the importance of responses to low sugar in diurnal gene regulation. We identified a set of candidate regulatory genes that show robust responses to alterations in sugar levels and change markedly during the diurnal cycle. PMID:16299223

  16. Diurnal variation of the human adipose transcriptome and the link to metabolic disease

    PubMed Central

    Loboda, Andrey; Kraft, Walter K; Fine, Bernard; Joseph, Jeffrey; Nebozhyn, Michael; Zhang, Chunsheng; He, Yudong; Yang, Xia; Wright, Christopher; Morris, Mark; Chalikonda, Ira; Ferguson, Mark; Emilsson, Valur; Leonardson, Amy; Lamb, John; Dai, Hongyue; Schadt, Eric; Greenberg, Howard E; Lum, Pek Yee

    2009-01-01

    Background Circadian (diurnal) rhythm is an integral part of the physiology of the body; specifically, sleep, feeding behavior and metabolism are tightly linked to the light-dark cycle dictated by earth's rotation. Methods The present study examines the effect of diurnal rhythm on gene expression in the subcutaneous adipose tissue of overweight to mildly obese, healthy individuals. In this well-controlled clinical study, adipose biopsies were taken in the morning, afternoon and evening from individuals in three study arms: treatment with the weight loss drug sibutramine/fasted, placebo/fed and placebo/fasted. Results The results indicated that diurnal rhythm was the most significant driver of gene expression variation in the human adipose tissue, with at least 25% of the genes having had significant changes in their expression levels during the course of the day. The mRNA expression levels of core clock genes at a specific time of day were consistent across multiple subjects on different days in all three arms, indicating robust diurnal regulation irrespective of potential confounding factors. The genes essential for energy metabolism and tissue physiology were part of the diurnal signature. We hypothesize that the diurnal transition of the expression of energy metabolism genes reflects the shift in the adipose tissue from an energy-expending state in the morning to an energy-storing state in the evening. Consistent with this hypothesis, the diurnal transition was delayed by fasting and treatment with sibutramine. Finally, an in silico comparison of the diurnal signature with data from the publicly-available Connectivity Map demonstrated a significant association with transcripts that were repressed by mTOR inhibitors, suggesting a possible link between mTOR signaling, diurnal gene expression and metabolic regulation. Conclusion Diurnal rhythm plays an important role in the physiology and regulation of energy metabolism in the adipose tissue and should be

  17. Diurnal variation of oxygen and carbonate system parameters in Tampa Bay and Florida Bay

    USGS Publications Warehouse

    Yates, K.K.; Dufore, C.; Smiley, N.; Jackson, C.; Halley, R.B.

    2007-01-01

    Oxygen and carbonate system parameters were measured, in situ, over diurnal cycles in Tampa Bay and Florida Bay, Florida. All system parameters showed distinct diurnal trends in Tampa Bay with an average range of diurnal variation of 39.1 μmol kg− 1 for total alkalinity, 165.1 μmol kg− 1 for total CO2, 0.22 for pH, 0.093 mmol L− 1 for dissolved oxygen, and 218.1 μatm for pCO2. Average range of diurnal variation for system parameters in Tampa Bay was 73% to 93% of the seasonal range of variability for dissolved oxygen and pH. All system parameters measured in Florida Bay showed distinct variation over diurnal time-scales. However, clear diurnal trends were less evident. The average range of diurnal variability in Florida Bay was 62.8 μmol kg− 1 for total alkalinity, 130.4 μmol kg− 1 for total CO2, 0.13 for pH, 0.053 mmol L− 1 for dissolved oxygen, and 139.8 μatm for pCO2. The average range of diurnal variation was 14% to 102% of the seasonal ranges for these parameters. Diurnal variability in system parameters was most influenced by primary productivity and respiration of benthic communities in Tampa Bay, and by precipitation and dissolution of calcium carbonate in Florida Bay. Our data indicate that use of seasonal data sets without careful consideration of diurnal variability may impart significant error in calculations of annual carbon and oxygen budgets. These observations reinforce the need for higher temporal resolution measurements of oxygen and carbon system parameters in coastal ecosystems.

  18. Chronic non-invasive corticosterone administration abolishes the diurnal pattern of tph2 expression

    PubMed Central

    Donner, Nina C.; Montoya, Christian D.; Lukkes, Jodi L.; Lowry, Christopher A.

    2011-01-01

    Both hypothalamic-pituitary-adrenal (HPA) axis activity and serotonergic systems are commonly dysregulated in stress-related psychiatric disorders. We describe here a non-invasive rat model for hypercortisolism, as observed in major depression, and its effects on physiology, behavior, and the expression of tph2, the gene encoding tryptophan hydroxylase 2, the rate-limiting enzyme for brain serotonin (5-hydroxytryptamine; 5-HT) synthesis. We delivered corticosterone (40 µg/ml, 100 µg/ml or 400 µg/ml) or vehicle to adrenal-intact adult, male rats via the drinking water for three weeks. On days 15, 16, 17 and 18, respectively, the rats’ emotionality was assessed in the open-field (OF), social interaction (SI), elevated plus-maze (EPM), and forced swim tests (FST). On day 21, half of the rats in each group were killed 2 h into the dark phase of a 12/12 h reversed light/dark cycle; the other half were killed 2 h into the light phase. We then measured indices of HPA axis activity, plasma glucose and interleukin-6 (IL-6) availability, and neuronal tph2 expression at each time point. Chronic corticosterone intake was sufficient to cause increased anxiety- and depressive-like behavior in a dose-dependent manner. It also disrupted the diurnal pattern of plasma adrenocorticotropin (ACTH), corticosterone, and glucose concentrations, caused adrenal atrophy, and prevented regular weight gain. No diurnal or treatment-dependent changes were found for plasma levels of IL-6. Remarkably, all doses of corticosterone treatment abolished the diurnal variation of tph2 mRNA expression in the brainstem dorsal raphe nucleus (DR) by elevating the gene’s expression during the animals’ inactive (light) phase. Our data demonstrate that chronic elevation of corticosterone creates a vulnerability to a depression-like syndrome that is associated with increased tph2 expression, similar to that observed in depressed patients. PMID:21924839

  19. Diurnal Emotional States Impact the Sleep Course

    PubMed Central

    Delannoy, Julien; Mandai, Osamu; Honoré, Jacques; Kobayashi, Toshinori; Sequeira, Henrique

    2015-01-01

    Background Diurnal emotional experiences seem to affect several characteristics of sleep architecture. However, this influence remains unclear, especially for positive emotions. In addition, electrodermal activity (EDA), a sympathetic robust indicator of emotional arousal, differs depending on the sleep stage. The present research has a double aim: to identify the specific effects of pre-sleep emotional states on the architecture of the subsequent sleep period; to relate such states to the sympathetic activation during the same sleep period. Methods Twelve healthy volunteers (20.1 ± 1.0 yo.) participated in the experiment and each one slept 9 nights at the laboratory, divided into 3 sessions, one per week. Each session was organized over three nights. A reference night, allowing baseline pre-sleep and sleep recordings, preceded an experimental night before which participants watched a negative, neutral, or positive movie. The third and last night was devoted to analyzing the potential recovery or persistence of emotional effects induced before the experimental night. Standard polysomnography and EDA were recorded during all the nights. Results Firstly, we found that experimental pre-sleep emotional induction increased the Rapid Eye Movement (REM) sleep rate following both negative and positive movies. While this increase was spread over the whole night for positive induction, it was limited to the second half of the sleep period for negative induction. Secondly, the valence of the pre-sleep movie also impacted the sympathetic activation during Non-REM stage 3 sleep, which increased after negative induction and decreased after positive induction. Conclusion Pre-sleep controlled emotional states impacted the subsequent REM sleep rate and modulated the sympathetic activity during the sleep period. The outcomes of this study offer interesting perspectives related to the effect of diurnal emotional influences on sleep regulation and open new avenues for potential

  20. Diurnal variations of Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Müller-Wodarg, I. C. F.; Cravens, T. E.; Kasprzak, W. T.; Waite, J. H.

    2009-06-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1000 and 1300 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from eight close encounters of the Cassini spacecraft with Titan. Although there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ˜700 cm-3 below ˜1300 km. Such a plateau is a combined result of significant depletion of light ions and modest depletion of heavy ones on Titan's nightside. We propose that the distinctions between the diurnal variations of light and heavy ions are associated with their different chemical loss pathways, with the former primarily through “fast” ion-neutral chemistry and the latter through “slow” electron dissociative recombination. The strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes suggests a scenario in which the ions created on Titan's dayside may survive well to the nightside. The observed asymmetry between the dawn and dusk ion density profiles also supports such an interpretation. We construct a time-dependent ion chemistry model to investigate the effect of ion survival associated with solid body rotation alone as well as superrotating horizontal winds. For long-lived ions, the predicted diurnal variations have similar general characteristics to those observed. However, for short-lived ions, the model densities on the nightside are significantly lower than the observed values. This implies that electron precipitation from Saturn's magnetosphere may be an additional and important contributor to the densities of the short-lived ions observed on Titan's nightside.

  1. Diurnal variation of mesospheric ozone

    NASA Astrophysics Data System (ADS)

    Vaughan, G.

    1982-03-01

    Four Petrel rockets were flown from South Uist on October 2, 1979, to investigate the ozone concentration variation predicted by photochemical models between day and night in the mesosphere by means of interference filters that defined an approximately 10 nm bandwidth. The first two rockets contained photometers with wavebands centered at 265 and 290 nm, while the last two employed a single waveband at 265 nm. Results show significant diurnal variation above 54 km, which exceeds a factor of 2 above 65 km and reaches a factor of 10 between night and sunrise at 90 km.

  2. Diurnal changes in ocean color in coastal waters

    NASA Astrophysics Data System (ADS)

    Arnone, Robert; Vandermeulen, Ryan; Ladner, Sherwin; Ondrusek, Michael; Kovach, Charles; Yang, Haoping; Salisbury, Joseph

    2016-05-01

    Coastal processes can change on hourly time scales in response to tides, winds and biological activity, which can influence the color of surface waters. These temporal and spatial ocean color changes require satellite validation for applications using bio-optical products to delineate diurnal processes. The diurnal color change and capability for satellite ocean color response were determined with in situ and satellite observations. Hourly variations in satellite ocean color are dependent on several properties which include: a) sensor characterization b) advection of water masses and c) diurnal response of biological and optical water properties. The in situ diurnal changes in ocean color in a dynamic turbid coastal region in the northern Gulf of Mexico were characterized using above water spectral radiometry from an AErosol RObotic NETwork (AERONET -WavCIS CSI-06) site that provides up to 8-10 observations per day (in 15-30 minute increments). These in situ diurnal changes were used to validate and quantify natural bio-optical fluctuations in satellite ocean color measurements. Satellite capability to detect changes in ocean color was characterized by using overlapping afternoon orbits of the VIIRS-NPP ocean color sensor within 100 minutes. Results show the capability of multiple satellite observations to monitor hourly color changes in dynamic coastal regions that are impacted by tides, re-suspension, and river plume dispersion. Hourly changes in satellite ocean color were validated with in situ observation on multiple occurrences during different times of the afternoon. Also, the spatial variability of VIIRS diurnal changes shows the occurrence and displacement of phytoplankton blooms and decay during the afternoon period. Results suggest that determining the temporal and spatial changes in a color / phytoplankton bloom from the morning to afternoon time period will require additional satellite coverage periods in the coastal zone.

  3. Computational Simulation of the Activation Cycle of Gα Subunit in the G Protein Cycle Using an Elastic Network Model

    PubMed Central

    Kim, Min Hyeok; Kim, Young Jin; Kim, Hee Ryung; Jeon, Tae-Joon; Choi, Jae Boong; Chung, Ka Young; Kim, Moon Ki

    2016-01-01

    Agonist-activated G protein-coupled receptors (GPCRs) interact with GDP-bound G protein heterotrimers (Gαβγ) promoting GDP/GTP exchange, which results in dissociation of Gα from the receptor and Gβγ. The GTPase activity of Gα hydrolyzes GTP to GDP, and the GDP-bound Gα interacts with Gβγ, forming a GDP-bound G protein heterotrimer. The G protein cycle is allosterically modulated by conformational changes of the Gα subunit. Although biochemical and biophysical methods have elucidated the structure and dynamics of Gα, the precise conformational mechanisms underlying the G protein cycle are not fully understood yet. Simulation methods could help to provide additional details to gain further insight into G protein signal transduction mechanisms. In this study, using the available X-ray crystal structures of Gα, we simulated the entire G protein cycle and described not only the steric features of the Gα structure, but also conformational changes at each step. Each reference structure in the G protein cycle was modeled as an elastic network model and subjected to normal mode analysis. Our simulation data suggests that activated receptors trigger conformational changes of the Gα subunit that are thermodynamically favorable for opening of the nucleotide-binding pocket and GDP release. Furthermore, the effects of GTP binding and hydrolysis on mobility changes of the C and N termini and switch regions are elucidated. In summary, our simulation results enabled us to provide detailed descriptions of the structural and dynamic features of the G protein cycle. PMID:27483005

  4. Diurnal variation of rainfall in the Yangtze River Valley during the spring-summer transition from TRMM measurements

    NASA Astrophysics Data System (ADS)

    Chen, Guixing; Sha, Weiming; Iwasaki, Toshiki; Ueno, Kenichi

    2012-03-01

    A 12 year archive of the Tropical Rainfall Measuring Mission (TRMM) rain rate is used to document the regionality of diurnal rainfall cycle in the Yangtze River Valley (YRV). The regional rain peaks, local phase shifts, rain event's behavior, and related seasonal change from March to August are examined. In the middle reach of YRV, rainfall appears mainly in early morning and displays a distinct local shift of diurnal phase. Such features are well established at each presummer (from May to June) and result from the eastward migrating events with a late night growth in size. They are supported by the low-level convergence that moves from the east slope of the Tibetan Plateau to the middle reach of YRV, as the deviated wind vector rotates clockwise to enhance southerlies at late night and southwesterlies in the morning. In the lower reach of YRV, however, one observes an eruption of morning rainfall with less local difference in diurnal phase. Morning rainfall is active in presummers of some years but suppressed in some others, contributing greatly to the variance of rainfall budget and resulting in anomalous wet/dry seasons. It is found to arise from a local growth of rain events rather than the migrating events from the middle reach. A majority of these organized convections prefer to form and develop in a belt-shaped zone where the nocturnal southwesterlies of warm/moist air impinge on the Meiyu front in the lower troposphere.

  5. Performance improvement: an active life cycle product management

    NASA Astrophysics Data System (ADS)

    Cucchiella, Federica; Gastaldi, Massimo; Lenny Koh, S. C.

    2010-03-01

    The management of the supply chain has gained importance in many manufacturing firms. Operational flexibility can be considered a crucial weapon to increase competitiveness in a turbulent marketplace. It reflects the ability of a firm to properly and rapidly respond to a variable and dynamic environment. For the firm operating in a fashion sector, the management of the supply chain is even more complex because the product life cycle is shorter than that of the firm operating in a non-fashion sector. The increase of firm flexibility level can be reached through the application of the real option theory inside the firm network. In fact, real option may increase the project value by allowing managers to more efficiently direct the production. The real option application usually analysed in literature does not take into account that the demands of products are well-defined by the product life cycle. Working on a fashion sector, the life cycle pattern is even more relevant because of an expected demand that grows according to a constant rate that does not capture the demand dynamics of the underlying fashion goods. Thus, the primary research objective of this article is to develop a model useful for the management of investments in a supply chain operating in a fashion sector where the system complexity is increased by the low level of unpredictability and stability that is proper of the mood phenomenon. Moreover, unlike the traditional model, a real option framework is presented here that considers fashion product characterised by uncertain stages of the production cycle.

  6. Cdk1 activity acts as a quantitative platform for coordinating cell cycle progression with periodic transcription

    PubMed Central

    Banyai, Gabor; Baïdi, Feriel; Coudreuse, Damien; Szilagyi, Zsolt

    2016-01-01

    Cell proliferation is regulated by cyclin-dependent kinases (Cdks) and requires the periodic expression of particular gene clusters in different cell cycle phases. However, the interplay between the networks that generate these transcriptional oscillations and the core cell cycle machinery remains largely unexplored. In this work, we use a synthetic regulable Cdk1 module to demonstrate that periodic expression is governed by quantitative changes in Cdk1 activity, with different clusters directly responding to specific activity levels. We further establish that cell cycle events neither participate in nor interfere with the Cdk1-driven transcriptional program, provided that cells are exposed to the appropriate Cdk1 activities. These findings contrast with current models that propose self-sustained and Cdk1-independent transcriptional oscillations. Our work therefore supports a model in which Cdk1 activity serves as a quantitative platform for coordinating cell cycle transitions with the expression of critical genes to bring about proper cell cycle progression. PMID:27045731

  7. Prediction of solar activity from solar background magnetic field variations in cycles 21-23

    SciTech Connect

    Shepherd, Simon J.; Zharkov, Sergei I.; Zharkova, Valentina V. E-mail: s.zharkov@hull.ac.uk

    2014-11-01

    A comprehensive spectral analysis of both the solar background magnetic field (SBMF) in cycles 21-23 and the sunspot magnetic field in cycle 23 reported in our recent paper showed the presence of two principal components (PCs) of SBMF having opposite polarity, e.g., originating in the northern and southern hemispheres, respectively. Over a duration of one solar cycle, both waves are found to travel with an increasing phase shift toward the northern hemisphere in odd cycles 21 and 23 and to the southern hemisphere in even cycle 22. These waves were linked to solar dynamo waves assumed to form in different layers of the solar interior. In this paper, for the first time, the PCs of SBMF in cycles 21-23 are analyzed with the symbolic regression technique using Hamiltonian principles, allowing us to uncover the underlying mathematical laws governing these complex waves in the SBMF presented by PCs and to extrapolate these PCs to cycles 24-26. The PCs predicted for cycle 24 very closely fit (with an accuracy better than 98%) the PCs derived from the SBMF observations in this cycle. This approach also predicts a strong reduction of the SBMF in cycles 25 and 26 and, thus, a reduction of the resulting solar activity. This decrease is accompanied by an increasing phase shift between the two predicted PCs (magnetic waves) in cycle 25 leading to their full separation into the opposite hemispheres in cycle 26. The variations of the modulus summary of the two PCs in SBMF reveals a remarkable resemblance to the average number of sunspots in cycles 21-24 and to predictions of reduced sunspot numbers compared to cycle 24: 80% in cycle 25 and 40% in cycle 26.

  8. Altered lower leg muscle activation patterns in patients with cerebral palsy during cycling on an ergometer

    PubMed Central

    Alves-Pinto, Ana; Blumenstein, Tobias; Turova, Varvara; Lampe, Renée

    2016-01-01

    Objective Cycling on a recumbent ergometer constitutes one of the most popular rehabilitation exercises in cerebral palsy (CP). However, no control is performed on how muscles are being used during training. Given that patients with CP present altered muscular activity patterns during cycling or walking, it is possible that an incorrect pattern of muscle activation is being promoted during rehabilitation cycling. This study investigated patterns of muscular activation during cycling on a recumbent ergometer in patients with CP and whether those patterns are determined by the degree of spasticity and of mobility. Methods Electromyographic (EMG) recordings of lower leg muscle activation during cycling on a recumbent ergometer were performed in 14 adult patients diagnosed with CP and five adult healthy participants. EMG recordings were done with an eight-channel EMG system built in the laboratory. The activity of the following muscles was recorded: Musculus rectus femoris, Musculus biceps femoris, Musculus tibialis anterior, and Musculus gastrocnemius. The degree of muscle spasticity and mobility was assessed using the Modified Ashworth Scale and the Gross Motor Function Classification System, respectively. Muscle activation patterns were described in terms of onset and duration of activation as well as duration of cocontractions. Results Muscle activation in CP was characterized by earlier onsets, longer periods of activation, a higher occurrence of agonist–antagonist cocontractions, and a more variable cycling tempo in comparison to healthy participants. The degree of altered muscle activation pattern correlated significantly with the degree of spasticity. Conclusion This study confirmed the occurrence of altered lower leg muscle activation patterns in patients with CP during cycling on a recumbent ergometer. There is a need to develop feedback systems that can inform patients and therapists of an incorrect muscle activation during cycling and support the training

  9. Impact of land-sea breezes at different scales on the diurnal rainfall in Taiwan

    NASA Astrophysics Data System (ADS)

    Huang, Wan-Ru; Wang, Shih-Yu

    2014-10-01

    The formation mechanism of diurnal rainfall in Taiwan is commonly recognized as a result of local forcings involving solar thermal heating and island-scale land-sea breeze (LSB) interacting with orography. This study found that the diurnal variation of the large-scale circulation over the East Asia-Western North Pacific (EAWNP) modulates considerably the diurnal rainfall in Taiwan. It is shown that the interaction between the two LSB systems—the island-scale LSB and the large-scale LSB over EAWNP—facilitates the formation of the early morning rainfall in western Taiwan, afternoon rainfall in central Taiwan, and nighttime rainfall in eastern Taiwan. Moreover, the post-1998 strengthening of a shallow, low-level southerly wind belt along the coast of Southeast China appears to intensify the diurnal rainfall activity in Taiwan. These findings reveal the role of the large-scale LSB and its long-term variation in the modulation of local diurnal rainfall.

  10. Impact of Land-Sea Breezes at Different Scales on the Diurnal Rainfall in Taiwan

    NASA Astrophysics Data System (ADS)

    Huang, Wan-Ru; Wang, Shih-Yu

    2014-05-01

    The formation mechanism of diurnal rainfall in Taiwan is commonly recognized as a result of local forcings involving solar thermal heating and island-scale land-sea breeze (LSB) interacting with orography. This study found that the diurnal variation of the large-scale circulation over the East Asia-Western North Pacific (EAWNP) modulates considerably the diurnal rainfall in Taiwan. It is shown that the interaction between the two LSB systems - the island-scale LSB and the large-scale LSB over EAWNP - facilitates the formation of the early morning rainfall in western Taiwan, afternoon rainfall in central Taiwan, and nighttime rainfall in eastern Taiwan. Moreover, the post-1998 strengthening of a shallow, low-level southerly wind belt along the coast of Southeast China appears to intensify the diurnal rainfall activity in Taiwan. These findings reveal the role of the large-scale LSB and its long-term variation in the modulation of local diurnal rainfall.

  11. Thermospheric composition. [latitudinal, seasonal and diurnal variations

    NASA Technical Reports Server (NTRS)

    Carignan, G. R.

    1975-01-01

    The global view of the atmosphere provided by satellite observations and radar backscatter measurements has shown a pattern of composition variability resulting largely from dynamic processes. Important progress has been made in defining composition variability at 120 km, which has greatly improved models which previously had fixed boundary conditions at that altitude. The discovery of the early morning maximum in helium abundance and the better definition of diurnal variation in relative composition have provided a basis for more sophisticated dynamical models. Similarly, models of meridional wind systems have been developed which can account for the better-defined winter enhancements in helium and atomic oxygen. Finally, composition variability has indicated the presence of a high-latitude heat source which during periods of magnetic activity profoundly modifies the state of the atmosphere.

  12. Diurnal temperature effect on nitrate removal and production efficiency in bedform-induced hyporheic zones

    NASA Astrophysics Data System (ADS)

    Zheng, L.; Cardenas, M. B.

    2014-12-01

    Rivers and aquifers are connected through the hyporheic zone (HZ). Pore water in the subsurface sediments is continuously exchanged with the overlying surface water. The exchange of water, mass and energy occurring along the surface-subsurface interface or within the HZ exerts a strong influence on the quality of both surface and subsurface waters, and fluvial ecology. Moreover, the HZ is rich in biologically active sediment, creating a favorable condition for microbially-facilitated reactions to occur, including organic carbon oxidation (aerobic respiration), nitrification, and denitrification. Inorganic N, especially NO3-, is of concern as a drinking water pollutant and as a cause for eutrophication that threatens ecosystems. The biogeochemical reactions in the HZ could produce or consume NO3- and thus the HZ could serve a nitrate source or sink role in the fluvial system. In addition, hyporheic exchange across the sediment-water interface (SWI) leads to penetration of diel temperature cycles from the river, leading to dynamic HZ temperature pattern. This in turn affects biogeochemical reactions in the HZ. The main objective of this study is to integrate all the processes that occur along the SWI to understand how diurnal temperature variations affect the biogeochemical function of the HZ. We conducted numerical simulations of coupled turbulent open-channel fluid flow, porous fluid flow, porous heat transport and reactive solute transport to study feedbacks and coupling between these processes. We assumed sinusoidally varying diurnal temperature variations. We studied the effects of different mean temperatures and different amplitudes of the diurnal temperature variations on nitrate removal or production efficiency in the HZ. The simulation results show that the average temperature effect on the HZ nitrate source-sink functionality and its associated efficiency has strong dependence on the [NO3-]/[NH4+ ] ratio in the river. However, the effects of the

  13. Respiratory Muscle Activity During Simultaneous Stationary Cycling and Inspiratory Muscle Training.

    PubMed

    Hellyer, Nathan J; Folsom, Ian A; Gaz, Dan V; Kakuk, Alynn C; Mack, Jessica L; Ver Mulm, Jacyln A

    2015-12-01

    Inspiratory muscle training (IMT) strengthens the muscles of respiration, improves breathing efficiency, and increases fitness. The IMT is generally performed independently of aerobic exercise; however, it is not clear whether there is added benefit of performing the IMT while simultaneously performing aerobic exercise in terms of activating and strengthening inspiratory muscles. The purpose of our study was to determine the effect of IMT on respiratory muscle electromyography (EMG) activity during stationary cycling in the upright and drops postures as compared with that when the IMT was performed alone. Diaphragm and sternocleidomastoid EMG activity was measured under different resting and cycling postures, with and without the use of the IMT at 40% maximal inspiratory pressure (n = 10; mean age 37). Cycling in an upright posture while simultaneously performing the IMT resulted in a significantly greater diaphragm EMG activity than while performing the IMT at rest in upright or drops postures (p ≤ 0.05). Cycling in drops postures while performing the IMT had a significantly greater diaphragm EMG activity than when performing the IMT at rest in either upright or drops postures (p ≤ 0.05). Sternocleidomastoid muscle activity increased with both cycling and IMT, although posture had little effect. These results support our hypothesis in that the IMT while cycling increases respiratory EMG activity to a significantly greater extent than when performing the IMT solely at rest, suggesting that the combination of IMT and cycling may provide an additive training effect. PMID:26584054

  14. Unusual Migration of Prominence Activities in the Southern Hemisphere during Cycles 23-24

    NASA Astrophysics Data System (ADS)

    Shimojo, Masumi

    2013-12-01

    The solar activity in Cycles 23-24 shows differences from the previous cycles that were observed with modern instruments, e.g., long cycle duration and a small number of sunspots. To appreciate the anomalies further, we investigated the prominence eruptions and disappearances observed with the Nobeyama Radioheliograph for over 20 years. Consequently, we found that the occurrence of prominence activities in the northern hemisphere is normal because the period of the number variation is 11 years, and the migration of the producing region of the prominence activities traces the migration of 11 years ago. On the other hand, the migration in the southern hemisphere significantly differs from that in the northern hemisphere and the previous cycles. The prominence activities occurred over -50° latitude in spite of the late decay phase of Cycle 23, and the number of prominence activities in the higher latitude region (over -65°) is very small, even near the solar maximum of Cycle 24. The results suggest that the anomalies of the global magnetic field distribution started at the solar maximum of Cycle 23. A comparison of the butterfly diagram of the prominence activities with the magnetic butterfly diagram indicates that the timing of "the rush to the pole" and the polar magnetic field closely relates to unusual migration. Considering that the rush to the pole is made of the sunspots, the hemispheric asymmetry of the sunspots and the strength of the polar magnetic fields are essential for understanding the anomalies of the prominence activities.

  15. The Life Cycle of Active Region Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Cheung, M. C. M.; van Driel-Gesztelyi, L.; Martínez Pillet, V.; Thompson, M. J.

    2016-08-01

    We present a contemporary view of how solar active region magnetic fields are understood to be generated, transported and dispersed. Empirical trends of active region properties that guide model development are discussed. Physical principles considered important for active region evolution are introduced and advances in modeling are reviewed.

  16. Climate–vegetation control on the diurnal and seasonal variations of surface urban heat islands in China

    NASA Astrophysics Data System (ADS)

    Zhou, Decheng; Zhang, Liangxia; Li, Dan; Huang, Dian; Zhu, Chao

    2016-07-01

    Remotely sensed surface urban heat islands (UHIs) have gained considerable interest in recent decades due to the easy access and the wall-to-wall coverage of satellite products. The magnitude or intensity of surface UHIs have been well documented at regional and global scales, yet a systematic evaluation of the temporal variability over large areas is still lacking. In this study, the diurnal and seasonal cycles of surface UHI intensities (SUHIIs) in China are examined using Aqua/Terra MODIS data from 2008 to 2012. Results show that the mean annual SUHIIs varied greatly in a diurnal cycle, characterized by a positive day-night difference (DND) in Southeast China and the opposite in Northeast and Northwest China. Also, the SUHIIs differed dramatically in a seasonal cycle, indicated by a positive summer-winter difference (SWD) in the day and a negative SWD at night, accompanied by the highly diverse DNDs across seasons and geographic regions. Northwest and Northeast China overall showed the largest DND and SWD (>3 °C), respectively. These diurnal and seasonal variations depend strongly on local climate-vegetation regimes, as indicated by a strong positive correlation between DND and precipitation (and air temperature) and a negative relationship between DND and vegetation activity across cities and seasons. In particular, SHUIIs were quadratically correlated with the mean annual precipitation across space, suggesting that there might be a threshold in terms of the effects induced by local background climate. Our findings highlight the importance of considering the temporal variability of UHIs for more accurate characterization of the associated ecological and social-economic consequences.

  17. Rhinosporidium seeberi Nuclear Cycle Activities Using Confocal Microscopy.

    PubMed

    Delfino, Darly; Mendoza, Leonel; Vilela, Raquel

    2016-02-01

    Rhinosporidium seeberi is an uncultivated Ichthyosporean infecting animals, including humans. Recent studies suggested R. seeberi undergoes synchronized nuclear division without cytokinesis. We used confocal microscopy to investigate R. seeberi nuclear division cycles in formalin-fixed tissues stained with DAPI and phalloidin. We report that R. seeberi nuclei in juvenile and intermediary sporangia synchronously divided without cytokinesis. Intermediary sporangia display numerous 3-4 μm nuclei at different mitotic stages as well as a thick inner layer with strong affinity for phalloidin. Mature sporangia showed numerous 5-12 μm cell-walled endospores, each containing a 2-4 μm in diameter nucleus. Phalloidin did not bind to the inner layers of mature sporangia or endospores. The development of a "germinative zone" in the inner layer of mature sporangia containing hundreds of nuclei was also confirmed. This study establishes that during the R. seeberi life cycle synchronous nuclear divisions without cytokinesis takes place, resulting in the formation of thousands of nuclei. Cytokinesis, on the other hand, is a 1-time event and occurs in the latest stages of intermediate sporangia, after the formation of thousands of nuclei and just before mature sporangia development. PMID:26461427

  18. Cycling for Students with ASD: Self-Regulation Promotes Sustained Physical Activity

    ERIC Educational Resources Information Center

    Todd, Teri; Reid, Greg; Butler-Kisber, Lynn

    2010-01-01

    Individuals with autism often lack motivation to engage in sustained physical activity. Three adolescents with severe autism participated in a 16-week program and each regularly completed 30 min of cycling at the end of program. This study investigated the effect of a self-regulation instructional strategy on sustained cycling, which included…

  19. Diurnal variations in CO2 flux from peatland floodplains: Implications for models of ecosystem respiration

    NASA Astrophysics Data System (ADS)

    Goulsbra, Claire; Rickards, Nathan; Brown, Sarah; Evans, Martin; Boult, Stephen; Alderson, Danielle

    2016-04-01

    Peatlands are important terrestrial carbon stores, and within these environments, floodplains have been identified as hotspots of carbon processing, potentially releasing substantial amounts of CO2 into the atmosphere. Previous monitoring campaigns have shown that such CO2 release from ecosystem respiration is linked not only to soil temperature and water table depth, but also to CO2 sequestration via primary productivity, thought to be because the root exudates produced during photosynthesis stimulate microbial activity. This suggests that extrapolation models that are parameterised on data collected during day light hours, when vegetation is photosynthesising, may overestimate ecosystem respiration rates at night, which has important implications for estimates of annual CO2 flux and carbon budgeting. To investigate this hypothesis, monitoring data is collected on the CO2 flux from UK peatland floodplains over the full diurnal cycle. This is done via ex-situ manual data collection from mesocosms using an infra-red gas analyser, and the in-situ automated collection of CO2 concentration data from boreholes within the peat using GasClams®. Preliminary data collected during the summer months suggest that night time respiration is suppressed compared to that during the day, and that the significant predictors of respiration are different when examining day and night time data. This highlights the importance of incorporating diurnal variations into models of ecosystem respiration.

  20. The impact of diurnal sleep on the consolidation of a complex gross motor adaptation task

    PubMed Central

    Hoedlmoser, Kerstin; Birklbauer, Juergen; Schabus, Manuel; Eibenberger, Patrick; Rigler, Sandra; Mueller, Erich

    2015-01-01

    Diurnal sleep effects on consolidation of a complex, ecological valid gross motor adaptation task were examined using a bicycle with an inverse steering device. We tested 24 male subjects aged between 20 and 29 years using a between-subjects design. Participants were trained to adapt to the inverse steering bicycle during 45 min. Performance was tested before (TEST1) and after (TEST2) training, as well as after a 2 h retention interval (TEST3). During retention, participants either slept or remained awake. To assess gross motor performance, subjects had to ride the inverse steering bicycle 3 × 30 m straight-line and 3 × 30 m through a slalom. Beyond riding time, we sophisticatedly measured performance accuracy (standard deviation of steering angle) in both conditions using a rotatory potentiometer. A significant decrease of accuracy during straight-line riding after nap and wakefulness was shown. Accuracy during slalom riding remained stable after wakefulness but was reduced after sleep. We found that the duration of rapid eye movement sleep as well as sleep spindle activity are negatively related with gross motor performance changes over sleep. Together these findings suggest that the consolidation of adaptation to a new steering device does not benefit from a 2 h midday nap. We speculate that in case of strongly overlearned motor patterns such as normal cycling, diurnal sleep spindles and rapid eye movement sleep might even help to protect everyday needed skills, and to rapidly forget newly acquired, interfering and irrelevant material. PMID:25256866

  1. Diurnal variations of tropical cyclone precipitationin

    NASA Astrophysics Data System (ADS)

    Wu, Q.

    2015-12-01

    Using 15 years of satellite-measured precipitation data and tropical cyclone (TC) information, this study estimates the diurnal variations of TC precipitation in its inner core and outer rainbands. It is found that for both weak (tropical storms to category 1 TCs) and strong (categories 2-5 TCs) storms over all six TC basins, the TC precipitation reaches its daily maximum in the morning, but the mean rain rate and diurnal variations are larger in the inner core than in the outer rainbands. With increasing radial distance from the TC center, the diurnal amplitude of precipitation decreases, and the peak time appears progressively later. The outward propagation of diurnal signals from the TC center dominates as an internal structure of the TC convective systems. For all basins examined, the diurnal precipitation maximum within the inner core of a strong storm occurs earlier than the maximum observed in non-TC precipitation; the same result is not found for the outer rainbands.

  2. Diurnal variation of galactic cosmic ray intensity on quiet days

    NASA Technical Reports Server (NTRS)

    Kumar, S.; Datt, S. C.

    1985-01-01

    A detailed study of the diurnal variation on long term basis was performed on geomagnetically quiet days using the experimental data of the cosmic ray intensity from the worldwide neutron monitoring stations. During the period when the polarity of the solar magnetic field in the Northern Hemisphere of the sun is negative the phase and amplitude of the diurnal anisotropy on quiet days was observed to remain almost constant. When the polarity of solar magnetic field in the Northern Hemisphere changes from negative to positive, a shift in the phase of the diurnal anisotropy on quiet days towards earlier hours is observed and the shift is found to be maximum during minimum solar activity periods 1953-54 and 1975-76. When the polarity of solar magnetic field changes from positive to negative in the Northern Hemisphere of the Sun the phase of the diurnal anisotropy on quiet days recovers to its usual direction of corotational anisotropy and is observed to remain almost constant till the polarity of the solar magnetic field does not change.

  3. Amygdala/hippocampal activation during the menstrual cycle: evidence for lateralization of effects across different tasks.

    PubMed

    Lisofsky, Nina; Lindenberger, Ulman; Kühn, Simone

    2015-01-01

    Variations in hormonal levels between the follicular and the luteal phase of the female menstrual cycle are associated with variations in emotional and cognitive aspects of behavior. The functional neural correlates of these cycle-related variations have been explored in previous neuroimaging studies. We summarize the existing findings of functional magnetic resonance imaging (fMRI) studies to identify regions of increased brain activation in the follicular or luteal phases of the cycle that are concordant across studies. Eleven fMRI studies reporting coordinates of higher brain activation in one of the two main cycle phases were included in the analysis. Activation likelihood estimation was used to determine concordance. We found higher left amygdala/hippocampal activation during the luteal phase and higher right amygdala/hippocampal activation during the follicular phase. Additionally, the anterior cingulate cortex and temporal pole showed increased activation during the luteal phase and the superior temporal gyrus during the follicular phase. The observed pattern of cycle-dependent functional lateralization of the amygdala/hippocampal complex is consistent with findings on cycle-related behavioral variations and on sex differences in lateralization of activity in amygdala and hippocampus. PMID:25496966

  4. Possible chromospheric activity cycles in II Peg, UX Ari and V711 Tau

    NASA Astrophysics Data System (ADS)

    Buccino, Andrea P.; Mauas, Pablo J. D.

    2009-02-01

    We study the Mount Wilson indices we obtained indirectly from IUE high and low resolution spectra of the RS CVn-type systems II Peg (K2IV), UX Ari (K0IV+G5V) and V711 Tau (K1IV+G5V), extensively observed by IUE from 1978 to 1996. We analyze the activity signatures, which correspond to the primary star, with the Lomb-Scargle periodogram. From the analysis of V711 Tau data, we found a possible chromospheric cycle with a period of 18 years and a shorter ~3 year cycle, which could be associated to a chromospheric flip-flop cycle. The data of II Peg also suggest a chromospheric cycle of ~21 years and a flip-flop cycle of ~9 years. Finally, we obtained a possible chromospheric cycle of ~6 years for UX Ari.

  5. Martian induced magnetosphere variations with solar activity cycle

    NASA Astrophysics Data System (ADS)

    Fedorov, Andrey; Ronan, Modolo; Jarninen, Riku; Mazelle, Christian; Barabash, Stas

    2014-05-01

    During the last 6 years of ESA Mars Express mission we have accumulated plasma data taken inside and around the Martian induced magnetosphere corresponding to the increasing branch of solar activity. This data allows to make an enhanced study of the magnetosphere variations as a response of the solar activity level. Since Mars Express has no onboard magnetometer, we used the hybrid models of the Martian plasma environment to get a proper frame to make an adequate statistics of the magnetospheric response. In this paper we present a spatial distribution of the planetary plasma in the planetary wake as well as the ionsospheric escape as a function of the solar activity.

  6. Does crustacean ethoxyresorufin O-deethylase activity vary during the molting cycle?

    PubMed

    Hotard, Kate; Zou, Enmin

    2013-10-01

    The authors examined fluctuation in microsomal ethoxyresorufin O-deethylase (EROD) activity in the hepatopancreas during the molting cycle of the fiddler crab, Uca pugilator. Results showed that microsomal EROD activity fluctuates significantly during the molting cycle, with the lowest enzymatic activity occurring in the late premolt stage. These results clearly show that molting physiology influences crustacean EROD activity, suggesting that when using crustacean EROD assays in evaluating pollution, only individuals from the same molt stage should be used. The authors propose that the high level of EROD activity in postmolt and intermolt stages is an additional mechanism crustaceans use to prevent any untimely rise in ecdysteroid levels. PMID:23843096

  7. Adrenal-dependent diurnal modulation of conditioned fear extinction learning

    PubMed Central

    Woodruff, Elizabeth R.; Greenwood, Benjamin N.; Chun, Lauren E.; Fardi, Sara; Hinds, Laura R.; Spencer, Robert L.

    2015-01-01

    Post Traumatic Stress Disorder (PTSD) is associated with altered conditioned fear extinction expression and impaired circadian function including dysregulation of glucocorticoid hormone secretion. We examined in adult male rats the relationship between conditioned fear extinction learning, circadian phase, and endogenous glucocorticoids (CORT). Rats maintained on a 12 hr light:dark cycle were trained and tested across 3 separate daily sessions (conditioned fear acquisition and 2 extinction sessions) that were administered during either the rats’ active or inactive circadian phase. In an initial experiment we found that rats at both circadian phases acquired and extinguished auditory cue conditioned fear to a similar degree in the first extinction session. However, rats trained and tested at zeitgeber time-16 (ZT16) (active phase) showed enhanced extinction memory expression during the second extinction session compared to rats trained and tested at ZT4 (inactive phase). In a follow-up experiment, adrenalectomized (ADX) or sham surgery rats were similarly trained and tested across 3 separate daily sessions at either ZT4 or ZT16. ADX had no effect on conditioned fear acquisition or conditioned fear memory. Sham ADX rats trained and tested at ZT16 exhibited better extinction learning across the two extinction sessions compared to all other groups of rats. These results indicate that conditioned fear extinction learning is modulated by time of day, and this diurnal modulation requires the presence of adrenal hormones. These results support an important role of CORT-dependent circadian processes in regulating conditioned fear extinction learning, which may be capitalized upon to optimize effective treatment of PTSD. PMID:25746455

  8. The Met Office's new operational analysis system for diurnally varying skin-SST

    NASA Astrophysics Data System (ADS)

    While, James; Mao, Chongyuan; Martin, Matthew; Good, Simon; Sykes, Peter

    2016-04-01

    Diurnal variations in skin Sea Surface Temperature (skin SST), which can be as large as several degrees, play an important role in determining the heat flux between the ocean and atmosphere. As such, since February 2015 the Met Office, as part of the Copernicus Marine Environment Monitoring Service (CMEMS), has been producing an operational analysis of the diurnal cycle of skin SST. This product consists of three components: an underlying 'foundation' SST (based on the OSTIA analysis), a warm layer where solar heating is important, and a cool skin where cooling due to long wave radiation dominates. A major development in this system is the use of a 4D-Var data assimilation technique with multiple outer-loops to improve estimates of the warm layer. Observations assimilated come from the SEVIRI, GOES-W, MTSAT2, and NOAA-AVHRR infra-red satellite instruments. Through their assimilation, the observations act to update the applied heat and wind flux such that the diurnal cycle in the warm layer is improved. In this presentation we describe the analysis system and how it produces a skin SST product. Particular attention is paid to the data assimilation aspects and on the observation processing. We also present results from a three month validation period showing that the system is well able to reproduce a drifter based climatology of the diurnal cycle in SST. A direct validation of our diurnal SST output against near surface Argo data is also given.

  9. Frowning and Jaw Clenching Muscle Activity Reflects the Perception of Effort During Incremental Workload Cycling

    PubMed Central

    Huang, Ding-Hau; Chou, Shih-Wei; Chen, Yi-Lang; Chiou, Wen-Ko

    2014-01-01

    The present study aimed to investigate whether facial electromyography (EMG) recordings reflect the perception of effort and primary active lower limb muscle activity during incremental workload cycling. The effects of exercise intensity on EMG activity of the corrugator supercilii (CS), masseter and vastus lateralis (VL) muscles, heart rate (HR) and the rating of perceived exertion (RPE) were investigated, and the correlations among these parameters were determined. Eighteen males and 15 females performed continuous incremental workload cycling exercise until exhaustion. CS, masseter and VL muscle activities were continuously recorded using EMG during exercise. HR was also continuously monitored during the test. During the final 30 s of each stage of cycle ergometer exercise, participants were asked to report their feeling of exertion on the adult OMNI-Cycle RPE. HR and EMG activity of the facial muscles and the primary active lower limb muscle were strongly correlated with RPE; they increased with power output. Furthermore, facial muscle activity increased significantly during high-intensity exercise. Masseter muscle activity was strongly and positively correlated with HR, RPE and VL activity. The present investigation supports the view that facial EMG activity reflects the perception of effort. The jaw clenching facial expression can be considered an important factor for improving the reporting of perceived effort during high-intensity exercise in males and females. Key points Frowning and jaw clenching muscle activity reflects the perception of effort during incremental workload cycling. EMG activity of the masseter muscle was strongly and positively correlated with RPE, HR and lower limb EMG activity during incremental workload cycling. The jaw clenching facial expression can be considered an important factor for estimating the intensity of effort. PMID:25435786

  10. A cell cycle-controlled redox switch regulates the topoisomerase IV activity

    PubMed Central

    Narayanan, Sharath; Janakiraman, Balaganesh; Kumar, Lokesh

    2015-01-01

    Topoisomerase IV (topo IV), an essential factor during chromosome segregation, resolves the catenated chromosomes at the end of each replication cycle. How the decatenating activity of the topo IV is regulated during the early stages of the chromosome cycle despite being in continuous association with the chromosome remains poorly understood. Here we report a novel cell cycle-regulated protein in Caulobacter crescentus, NstA (negative switch for topo IV decatenation activity), that inhibits the decatenation activity of the topo IV during early stages of the cell cycle. We demonstrate that in C. crescentus, NstA acts by binding to the ParC DNA-binding subunit of topo IV. Most importantly, we uncover a dynamic oscillation of the intracellular redox state during the cell cycle, which correlates with and controls NstA activity. Thus, we propose that predetermined dynamic intracellular redox fluctuations may act as a global regulatory switch to control cellular development and cell cycle progression and may help retain pathogens in a suitable cell cycle state when encountering redox stress from the host immune response. PMID:26063575

  11. Viral activities and life cycles in deep subseafloor sediments.

    PubMed

    Engelhardt, Tim; Orsi, William D; Jørgensen, Bo Barker

    2015-12-01

    Viruses are highly abundant in marine subsurface sediments and can even exceed the number of prokaryotes. However, their activity and quantitative impact on microbial populations are still poorly understood. Here, we use gene expression data from published continental margin subseafloor metatranscriptomes to qualitatively assess viral diversity and activity in sediments up to 159 metres below seafloor (mbsf). Mining of the metatranscriptomic data revealed 4651 representative viral homologues (RVHs), representing 2.2% of all metatranscriptome sequence reads, which have close translated homology (average 77%, range 60-97% amino acid identity) to viral proteins. Archaea-infecting RVHs are exclusively detected in the upper 30 mbsf, whereas RVHs for filamentous inoviruses predominate in the deepest sediment layers. RVHs indicative of lysogenic phage-host interactions and lytic activity, notably cell lysis, are detected at all analysed depths and suggest a dynamic virus-host association in the marine deep biosphere studied here. Ongoing lytic viral activity is further indicated by the expression of clustered, regularly interspaced, short palindromic repeat-associated cascade genes involved in cellular defence against viral attacks. The data indicate the activity of viruses in subsurface sediment of the Peruvian margin and suggest that viruses indeed cause cell mortality and may play an important role in the turnover of subseafloor microbial biomass. PMID:26109514

  12. Diurnal variation of tropospheric relative humidity in tropical regions

    NASA Astrophysics Data System (ADS)

    Moradi, Isaac; Arkin, Philip; Ferraro, Ralph; Eriksson, Patrick; Fetzer, Eric

    2016-06-01

    regions where the diurnal peak occurs at other times of the day. The early morning peak time is because of a peak in convective activities in early morning. Additionally, a double peak was observed in tropospheric humidity over some regions which is consistent with double peak in precipitation.

  13. Effect of suprachiasmatic lesions on diurnal heart rate rhythm in the rat

    NASA Technical Reports Server (NTRS)

    Saleh, M. A.; Winget, C. M.

    1977-01-01

    Heart rate and locomotor activity of rats kept under 12L/12D illumination regimen were recorded every six minutes for ten days using implantable radio transmitters. Some of the rats then received bilateral RF lesions into the suprachiasmatic nucleus (SCN). Control sham operations were performed on the rest of the animals. After recovery from surgery, recording of heart rate and locomotor activity was continued for ten days. SCN-lesioned rats showed no significant diurnal fluctuation in heart rate, while normal and sham-operated rats showed the normal diurnal rhythm in that function. The arrhythmic diurnal heart-rate pattern of SCN rats appeared to be correlated with their sporadic activity pattern. The integrity of the suprachiasmatic nucleus is therefore necessary for the generation and/or expression of diurnal rhythmicity in heart rate in the rat.

  14. Projected Increase in Diurnal and Inter-Diurnal Variations of European Summer Temperatures

    NASA Astrophysics Data System (ADS)

    Cattiaux, J.; Douville, H.; Schoetter, R.; Parey, S.; Yiou, P.

    2014-12-01

    The current European warming is expected to be associated with an increased temperature variability in summer, particularly at the daily time-scale. Such an increase would affect hot extremes and accentuate the societal and environmental impacts caused by the mean warming. Here we investigate future changes in the short-term variability of European summer temperatures using two indices that have been seldom documented so far: the variations within one day (diurnal temperature range, DTR) and the variations from one day to the next (inter-diurnal temperature variability, ITV). These rapid variations represent key issues for impact communities, in particular energy providers vulnerable to sudden surges in electricity demand. Besides, the ITV provides a measure of daily variability that is not disturbed by longer-term variations in the mean (e.g., seasonal cycle and/or a multi-year trend), whereas traditional measures such as standard deviation or variance are. We use 21st-century projections performed by 34 models of the CMIP5 ensemble under the three RCP 2.6, 4.5 and 8.5 scenarios. Models are evaluated over the present-day period against the E-OBS dataset. In Europe, both indices of summer temperature variability are projected to increase, with a rather good model agreement on the sign, while uncertainties remain on the amplitude. In particular, we show that extremely high day-to-day and/or diurnal temperature variations are expected to occur more frequently. We highlight the singularity of the European area, since ITV and DTR changes do not systematically coincide over other regions (e.g., the U.S). Then we investigate the physical processes underlying these ITV and DTR changes in the CMIP5 projections. The respective contributions of the summer drying of European soils, the reduction in cloud cover and the changes in large-scale dynamics are estimated. Finally, the possibility of reducing model uncertainties through constraints emerging from both present

  15. Life Cycle of the Salmon. Ocean Related Curriculum Activities.

    ERIC Educational Resources Information Center

    Tarabochia, Kathy

    The ocean affects all of our lives. Therefore, awareness of and information about the interconnections between humans and oceans are prerequisites to making sound decisions for the future. Project ORCA (Ocean Related Curriculum Activities) has developed interdisciplinary curriculum materials designed to meet the needs of students and teachers…

  16. Do Male And Female Cyclists' Cortical Activity Differ Before and During Cycling Exercise?

    PubMed

    Ludyga, Sebastian; Gronwald, Thomas; Hottenrott, Kuno

    2015-12-01

    Although men and women are suggested to vary in resistance to fatigue, possible sex difference in its central component have rarely been investigated via electroencephalography (EEG). Therefore, we examined differences in cortical activity between male and female cyclists (n = 26) during cycling exercise. Participants performed an incremental test to derive the anaerobic threshold from the lactate power curve. In addition, cyclists' cortical activity was recorded with EEG before and during cycling exercise. Whereas women showed higher frontal alpha and beta activity at rest, no sex-specific differences of relative EEG spectral power occurred during cycling at higher intensity. Women and men's brains respond similarly during submaximal cycling, as both sexes show an inverted U-shaped curve of alpha power. Therefore, sex differences observable at rest vanish after the onset of exercise. PMID:26866769

  17. Looking for activity cycles in late-type Kepler stars using time-frequency analysis

    NASA Astrophysics Data System (ADS)

    Vida, K.; Oláh, K.; Szabó, R.

    2014-07-01

    We analyse light curves covering four years of 39 fast-rotating (Prot ≲ 1 d) late-type active stars from the Kepler data base. Using time-frequency analysis (short-term Fourier transform), we find hints for activity cycles of 300-900 d at nine targets from the changing typical latitude of the starspots, which with the differential rotation of the stellar surface change the observed rotation period over the activity cycle. We also give a lowest estimation for the shear parameter of the differential rotation, which is ≈0.001 for the cycling targets. These results populate the less studied, short-period end of the rotation-cycle length relation.

  18. Contextualizing Solar Cycle 24: Report on the Development of a Homogenous Database of Bipolar Active Regions Spanning Four Cycles

    NASA Astrophysics Data System (ADS)

    Munoz-Jaramillo, A.; Werginz, Z. A.; DeLuca, M. D.; Vargas-Acosta, J. P.; Longcope, D. W.; Harvey, J. W.; Martens, P.; Zhang, J.; Vargas-Dominguez, S.; DeForest, C. E.; Lamb, D. A.

    2015-12-01

    The solar cycle can be understood as a process that alternates the large-scale magnetic field of the Sun between poloidal and toroidal configurations. Although the process that transitions the solar cycle between toroidal and poloidal phases is still not fully understood, theoretical studies, and observational evidence, suggest that this process is driven by the emergence and decay of bipolar magnetic regions (BMRs) at the photosphere. Furthermore, the emergence of BMRs at the photosphere is the main driver behind solar variability and solar activity in general; making the study of their properties doubly important for heliospheric physics. However, in spite of their critical role, there is still no unified catalog of BMRs spanning multiple instruments and covering the entire period of systematic measurement of the solar magnetic field (i.e. 1975 to present).In this presentation we discuss an ongoing project to address this deficiency by applying our Bipolar Active Region Detection (BARD) code on full disk magnetograms measured by the 512 (1975-1993) and SPMG (1992-2003) instruments at the Kitt Peak Vacuum Telescope (KPVT), SOHO/MDI (1996-2011) and SDO/HMI (2010-present). First we will discuss the results of our revitalization of 512 and SPMG KPVT data, then we will discuss how our BARD code operates, and finally report the results of our cross-callibration.The corrected and improved KPVT magnetograms will be made available through the National Solar Observatory (NSO) and Virtual Solar Observatory (VSO), including updated synoptic maps produced by running the corrected KPVT magnetograms though the SOLIS pipeline. The homogeneous active region database will be made public by the end of 2017 once it has reached a satisfactory level of quality and maturity. The Figure shows all bipolar active regions present in our database (as of Aug 2015) colored according to the sign of their leading polarity. Marker size is indicative of the total active region flux. Anti

  19. Peroxide bond strength of antimalarial drugs containing an endoperoxide cycle. Relation with biological activity.

    PubMed

    Fernández, Israel; Robert, Anne

    2011-06-01

    Several endoperoxide compounds are very efficient antimalarial analogues of the natural drug artemisinin. Quantum chemical calculations have been used to correlate the computed free energies of the O-O bond with respect to the total number of oxygen atoms contained in the cycle, and with the size/strain of the cycle (5- or 6-membered cycles). The gas-phase homolysis of the O-O bond has been studied for five- and six-membered oxygenated cycles which are models of the "real" drugs. Our results indicate that, in 6-membered cycles, the stability order is the following: 1,2-dioxane > 1,2,4-trioxane > 1,2,4,5-tetraoxane. In cycles containing 3 oxygen atoms, the 5-membered cycle 1,2,4-trioxolane was found much less stable than its 6-membered counterpart 1,2,4-trioxane. This feature indicates the possible role of the cycle strain for the O-O bond stability, and may also explain the high antimalarial activity of some trioxolane derivatives. Similar trends in the O-O bond strength have been found for the real antimalarial drugs. However, the O-O bond stability is not in itself a decisive argument to anticipate the antimalarial activity of drugs. PMID:21487624

  20. Diurnal rhythm of melatonin binding in the rat suprachiasmatic nucleus

    SciTech Connect

    Laitinen, J.T.; Castren, E.; Vakkuri, O.; Saavedra, J.M.

    1989-03-01

    We used quantitative in vitro autoradiography to localize and characterize 2-/sup 125/I-melatonin binding sites in the rat suprachiasmatic nuclei in relation to pineal melatonin production. In a light:dark cycle of 12:12 h, binding density exhibited significant diurnal variation with a peak at the dark-light transition and a trough 12 hours later. Saturation studies suggested that the decreased binding at light-dark transition might be due to a shift of the putative melatonin receptor to a low affinity state.

  1. Is the Valles caldera entering a new cycle of activity?

    SciTech Connect

    Wolff, J.A.; Gardner, J.N.

    1995-05-01

    The Valles caldera formed during two major rhyolitic ignimbrite eruptive episodes (the Bandelier Tuff) at 1.61 and 1.22 Ma, after some 12 m.y. of activity in the Jemez Mountains volcanic field, New Mexico. Several subsequent eruptions between 1.22 and 0.52 Ma produced dominantly high-silica rhyolite lava domes and tephras within the caldera. These were followed by a dormancy of 0.46 m.y. prior to the most recent intracaldera activity, the longest hiatus since the inception of the Bandelier magma system at approximately 1.8 Ma. The youngest volcanic activity at approximately 60 ka produced the SW moat rhyolites, a series of lavas and tuffs that display abundant petrologic evidence of being newly generated melts. Petrographic textures conform closely to published predictions for silicic magmas generated by intrusion of basaltic magma into continental crust. The Valles caldera may currently be the site of renewed silicic magma generation, induced by intrusion of mafic magma at depth. Recent seismic investigations revealed the presence of a large low-velocity anomaly in the lower crust beneath the caldera. The generally aseismic character of the caldera, despite abundant regional seismicity, may be attributed to a heated crustal column, the local effect of 13 m.y. of magmatism and emplacement of mid-crustal plutons. 24 refs., 3 figs.

  2. Cell cycle-dependent regulation of RNA polymerase II basal transcription activity.

    PubMed Central

    Yonaha, M; Chibazakura, T; Kitajima, S; Yasukochi, Y

    1995-01-01

    Regulation of transcription by RNA polymerase II (pol II) in eukaryotic cells requires both basal and regulatory transcription factors. In this report we have investigated in vitro pol II basal transcription activity during the cell cycle by using nuclear extracts from synchronized HeLa cells. It is shown that pol II basal transcription activity is low in the S and G2 phases and high in early G1 phase and TFIID is the rate limiting component of pol II basal transcription activity during the cell cycle. Further analyses reveal that TFIID exists as a less active form in the S and G2 phases and nuclear extracts from S and G2 phase cells contain a heat-sensitive repressor(s) of TATA box binding protein (TBP). These results suggest that pol II basal transcription activity is regulated by a qualitative change in the TFIID complex, which could involve repression of TBP, during the cell cycle. Images PMID:7479063

  3. The activity cycle of 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Snodgrass, C.; Barrera, L.; Boehnhardt, H.; Guilbert-Lepoutre, A.; Hainaut, O.; Hutsemékers, D.; Jehin, E.; Meech, K.; Opitom, C.; Schulz, R.; Tozzi, G.; Tubiana, C.

    2014-07-01

    We present ground-based observations of comet 67P/Churyumov-Gerasimenko, target of the Rosetta mission, and an assessment on its activity levels. Based on imaging in the R-band, we measure the brightness of the coma within various apertures and use this to assess the amount of dust in the coma. We find that the comet begins to show detectable activity at a pre-perihelion distance from the Sun of 4.3 au, and then shows a smooth increase in production to a peak around one month after perihelion passage. The behaviour of the comet is consistent from one orbit to another, based on archival images taken over three apparitions, and we therefore use the heliocentric lightcurve to make predictions for the 2014/5 period while Rosetta is operating at the comet. We find that the Afρ parameter, measured within an aperture of radius 10,000 km at the comet, is proportional to r^{-3.2}, pre-perihelion [1]. We also attempt to make predictions on the gas production rate by fitting a model to the observed brightness values. This is done by assuming various parameters about the nucleus and dust, many of which are reasonably well constrained for 67P, and solving an energy balance equation that gives the sublimation rate of various ices as a function of solar illumination [2]. The model then links the gas production rate to the total amount of dust in the coma, and its brightness. We find that only a small fraction of the surface area (1.4 %) needs to be active for water sublimation, with an extra peak (up to 4 %) for a month either side of perihelion, while an even smaller area is producing CO_2 (0.04-0.09 %) [1]. The predictions can now be tested against new observations, and we will present the latest results from our 2014 monitoring of 67P. We are performing regular R-band imaging on the comet using the VLT, and early indications in March 2014 indicate that the comet does appear to have returned to activity as expected. By the time of the ACM meeting we will have around 4 months

  4. Diurnal and longitudinal variations in the earth's ionosphere in the period of solstice in conditions of a deep minimum of solar activity

    NASA Astrophysics Data System (ADS)

    Klimenko, M. V.; Klimenko, V. V.; Bessarab, F. S.; Zakharenkova, I. E.; Vesnin, A. M.; Ratovsky, K. G.; Galkin, I. A.; Chernyak, Iu. V.; Yasyukevich, Yu. V.; Koren'kova, N. A.; Kotova, D. S.

    2016-01-01

    The results of studies of longitudinal and LT variations in parameters of the ionosphere-plasmasphere system, obtained using the Global Self-Consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP), assimilation ionospheric model IRI Real-Time Assimilation Mapping (IRTAM), and satellite and ground-based observational data are presented in the paper. The study of the main morphological features of longitudinal and LT variations in the critical frequency of the ionospheric F2 layer ( foF2) and total electron content ( TEC) depending on latitude in the winter solstice during a solar-activity minimum (December 22, 2009) is carried out. It is shown that the variations in foF2 and TEC, on the whole, are identical, and so mutually substitutable, while creating empirical models of these parameters in quiet geomagnetic conditions. The longitudinal and LT variations in both foF2 and TEC are within an order of magnitude everywhere except for the equator anomaly region, where LT variation is larger by an order of magnitude than longitudinal variation. According to the results of the study, in the American longitudinal sector at all latitudes of the Southern (summer) Hemisphere, maxima of foF2 and TEC are formed. The near-equatorial and high-latitudinal maxima are separated out from these. The estimate of the contribution into the longitudinal variation in foF2 and TEC for various local time sectors and at various latitudes has been obtained for the first time. In the Southern (summer) Hemisphere, longitudinal variation in foF2 and TEC is formed in the nighttime.

  5. On the existence of the 11-year cycle in solar activity before the Maunder minimum

    SciTech Connect

    Attolini, M.R.; Cecchini, S.; Cini Castagnoli, G.; Galli, M.; Nanni, T.

    1988-11-01

    The existence of the 11-year cycle in solar activity before the Maunder minimum is clearly demonstrated with cosmogenic /sup 10/Be in polar ice during 1180--1500 A.D. For that interval a periodicity of 11.4 +- 0.2 years is found with a high significance level. Indication of a cyclicity that resembles the Hale magnetic cycle is also observed at a lower significance level. A highly variable cyclicity in the band 9.5--11.5 years is also found in the record of historical aurorae which appears to be well correlated with the /sup 10/Be cyclicity for the same time interval. It is concluded that the Schwabe, or 11-year, cycle and the Hale magnetic cycle were present before and after the Maunder minimum, even though it is not possible to understand the variability of the cycle. copyright American Geophysical Union 1988

  6. Evaluating Diurnal Variations of Summer Precipitation over the Asian Monsoon Region based on TRMM Satellite Data and Coupled model outputs

    NASA Astrophysics Data System (ADS)

    Mao, J.; Wu, G.

    2013-12-01

    Climatological characteristics of diurnal variations in summer precipitation over the entire Asian monsoon region are comprehensively investigated based on the Tropical Rainfall Measuring Mission (TRMM) satellite data during 1998-2008. The amplitude and phase of diurnal precipitation show a distinct geographical pattern. Significant diurnal variations occur over most of continental and coastal areas including the Maritime Continent, with the relative amplitude exceeding 40%, indicating that the precipitation peak is 1.4 times the 24-h mean. Although the diurnal variations of summer precipitation over the continental areas are characterized by an afternoon peak (1500-1800 Local Solar Time (LST)), over the central Indochina Peninsula and central and southern Indian Peninsula the diurnal phase is delayed to after 2100 LST, suggesting the diurnal behaviors over these areas different from the general continental areas. The weak diurnal variations with relative amplitudes less than 40% exist mainly over oceanic areas in the western Pacific and most of Indian Ocean, with the rainfall peak mainly occurring from midnight to early morning (0000-0600 LST), indicating a typical oceanic regime characterized by an early morning peak. However, apparent exceptions occur over the South China Sea (SCS), Bay of Bengal (BOB), and eastern Arabian Sea, with the rainfall peak occurring in daytime (0900-1500 LST). Prominent meridional propagations of the diurnal phase exist in South Asia and East Asia. The diurnal precipitation variations are also evaluated using the simulated outputs from several coupled general circulation models (CGCMs) participating in CMIP3 (such as CNRM-CM3 and MRI-GCGM2.3.2) and CMIP5 (FGOALS-g2). As compared with those from TRMM data, current state-of-the-art CGCMs still have significant problems in simulating the diurnal variability of the Asian summer monsoon. Although most models can capture the amplitude and phase of the diurnal rainfall cycle over continental

  7. Solar Wind and Magnetic Storms in 24-th Cycle of Solar Activity

    NASA Astrophysics Data System (ADS)

    Val'chuk, T. E.

    2013-01-01

    Slow growth of 24-th solar cycle allows adding of this cycle to the type of low cycles. Geomagnetic activity is not expensive too - strong geomagnetic storms were absent in the beginning of growth branch of this cycle. Very prolonged minimum was lasting about 4 years. We may remember that century minimum of solar activity was proposed after XX century high strong cycles. It may be - we look this situation now in 2012. Our work is connected with sporadic phenomena in 24-th cycle. These more or less intensive variations of solar activity are not predicted, they are caused by flowing up of new magnetic fields of spots, the excitement of flares, intensive plasma flows, coronal mass ejections (CME) and filament eruptions. Now two last versions (CME and filaments) are primary. Geomagnetic activity on a descending phase of solar cycle depends on quality of coronal holes providing the recurrent geomagnetic storms. Sporadic phenomena, which generated geomagnetic storms in Earth magnetosphere if flare flows reached the Earth magnetosphere and transferred it the energy are more interesting for us - they are the valuable characteristics of 24-th cycle. The disturbed period of several geomagnetic storms was generated by solar active region N11429. It is one sample only, this case is difficult and indicative. Replacing each other scenarios describe geomagnetic variations at the beginning of March 2012. Detailed consideration of this interval revealed its communication with sporadic events on the Sun. The structural configuration of plasma in flare flows was defined by means fractal dimension calculations of solar plasma parameters: velocity Vx and density N in flare streams.

  8. Periods of Highly Synchronous, Non-Reentrant Endocardial Activation Cycles Occur During Long Duration Ventricular Fibrillation

    PubMed Central

    Robichaux, Robert P.; Dosdall, Derek J.; Osorio, Jose; Garner, Nicholas W.; Li, Li; Huang, Jian; Ideker, Raymond E.

    2010-01-01

    Background Little is known about long-duration ventricular fibrillation (LDVF), lasting 1-10 minutes when resuscitation is still possible. Methods and Results To determine global LV endocardial activation during LDVF, 6 canines (9.5±0.8 kg) received a 64-electrode basket catheter in the left ventricle (LV), a right ventricular (RV) catheter, and a 12-lead ECG. Activation sequences of 15 successive cycles after initiation and after 1, 2, 3, 5, 7, and 10 minutes of LDVF were determined. Early during VF, LV endocardial activation was complex and present throughout most (78.0±9.7%) of each cycle consistent with reentry. After 3-7 min of LDVF in 5 animals, endocardial activation became highly synchronized and present for only a small percentage of each cycle (18.2±7.7%), indicating that LV endocardial reentry was no longer present. During this synchronization, activations arose focally in Purkinje fibers and spread as large wavefronts to excite the Purkinje system followed by the subendocardial working myocardium. During this synchronization, the ECG continued to appear irregular, consistent with VF, and LV cycle length (183±29 ms) was significantly different than RV cycle length (144±14 ms) and significantly different than the LV cycle length when synchronization was not present (130±11 ms). Conclusion After 3-7 minutes of LDVF, a highly organized, synchronous, focal LV endocardial activation pattern frequently occurs that is not consistent with reentry but is consistent with triggered activity or abnormal automaticity in Purkinje fibers. The ECG continues to appear irregular during this period, partially because of differences in LV and RV cycle lengths. PMID:20487123

  9. Diurnal heating and cloudiness in the NCAR Community Climate Model (CCM2)

    NASA Technical Reports Server (NTRS)

    Lieberman, Ruth S.; Leovy, Conway B.; Boville, Byron A.; Briegleb, Bruce P.

    1994-01-01

    In this paper, the authors assess the suitability of the heating fileds in the latest version of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM2) for modeling the thermal forcing of atmospheric tides. Accordingly, diurnal variations of the surface pressure, outgoing longwave radiation (OLR), cloudiness, and precipitation are examined in the CCM2. The fields of radiative, sensible, and latent heating are similarly analyzed. These results are subjectively compared with available data. Equatorial diurnal surface pressure tides are fairly well simulated by CCM2. The model successfully reproduces the semidiurnal surface pressure tides; however, this may result in part from reflection of wave energy at the upper boundary. The CCM2 large-scale diurnal OLR is generally consistent with observations. The moist-convective scheme in the model is able to reproduce the diurnally varying cloudiness and precipitation patterns associated with land-sea contrasts; however, the amplitudes of CCM2 diurnal continental convective cloudiness are weaker than observations. The CCM2 boundary-layer sensible heating is consistent with a very limited set of observations, and with estimates obtained from simple models of diffusive heating. Although the CCM2 tropospheric solar radiative heating is similar in magnitude to previous estimates, there are substantial differences in the vertical structures. A definitive assessment of the validity of the CCM2 diurnal cycle is precluded by the lack of detailed observations and the limitations of our CCM2 sample. Nevertheless, the authors conclude that the global-scale components of the CCM2 diurnal heating are useful proxies for the true diurnal forcing of the tides.

  10. Active vibration and balance system for closed cycle thermodynamic machines

    NASA Technical Reports Server (NTRS)

    Qiu, Songgang (Inventor); Augenblick, John E. (Inventor); Peterson, Allen A. (Inventor); White, Maurice A. (Inventor)

    2004-01-01

    An active balance system is provided for counterbalancing vibrations of an axially reciprocating machine. The balance system includes a support member, a flexure assembly, a counterbalance mass, and a linear motor or an actuator. The support member is configured for attachment to the machine. The flexure assembly includes at least one flat spring having connections along a central portion and an outer peripheral portion. One of the central portion and the outer peripheral portion is fixedly mounted to the support member. The counterbalance mass is fixedly carried by the flexure assembly along another of the central portion and the outer peripheral portion. The linear motor has one of a stator and a mover fixedly mounted to the support member and another of the stator and the mover fixedly mounted to the counterbalance mass. The linear motor is operative to axially reciprocate the counterbalance mass. A method is also provided.

  11. TGEV nucleocapsid protein induces cell cycle arrest and apoptosis through activation of p53 signaling

    SciTech Connect

    Ding, Li; Huang, Yong; Du, Qian; Dong, Feng; Zhao, Xiaomin; Zhang, Wenlong; Xu, Xingang; Tong, Dewen

    2014-03-07

    Highlights: • TGEV N protein reduces cell viability by inducing cell cycle arrest and apoptosis. • TGEV N protein induces cell cycle arrest and apoptosis by regulating p53 signaling. • TGEV N protein plays important roles in TGEV-induced cell cycle arrest and apoptosis. - Abstract: Our previous studies showed that TGEV infection could induce cell cycle arrest and apoptosis via activation of p53 signaling in cultured host cells. However, it is unclear which viral gene causes these effects. In this study, we investigated the effects of TGEV nucleocapsid (N) protein on PK-15 cells. We found that TGEV N protein suppressed cell proliferation by causing cell cycle arrest at the S and G2/M phases and apoptosis. Characterization of various cellular proteins that are involved in regulating cell cycle progression demonstrated that the expression of N gene resulted in an accumulation of p53 and p21, which suppressed cyclin B1, cdc2 and cdk2 expression. Moreover, the expression of TGEV N gene promoted translocation of Bax to mitochondria, which in turn caused the release of cytochrome c, followed by activation of caspase-3, resulting in cell apoptosis in the transfected PK-15 cells following cell cycle arrest. Further studies showed that p53 inhibitor attenuated TGEV N protein induced cell cycle arrest at S and G2/M phases and apoptosis through reversing the expression changes of cdc2, cdk2 and cyclin B1 and the translocation changes of Bax and cytochrome c induced by TGEV N protein. Taken together, these results demonstrated that TGEV N protein might play an important role in TGEV infection-induced p53 activation and cell cycle arrest at the S and G2/M phases and apoptosis occurrence.

  12. OECD/NEA Ongoing activities related to the nuclear fuel cycle

    SciTech Connect

    Cornet, S.M.; McCarthy, K.; Chauvin, N.

    2013-07-01

    As part of its role in encouraging international collaboration, the OECD Nuclear Energy Agency is coordinating a series of projects related to the Nuclear Fuel Cycle. The Nuclear Science Committee (NSC) Working Party on Scientific Issues of the Nuclear Fuel Cycle (WPFC) comprises five different expert groups covering all aspects of the fuel cycle from front to back-end. Activities related to fuels, materials, physics, separation chemistry, and fuel cycles scenarios are being undertaken. By publishing state-of-the-art reports and organizing workshops, the groups are able to disseminate recent research advancements to the international community. Current activities mainly focus on advanced nuclear systems, and experts are working on analyzing results and establishing challenges associated to the adoption of new materials and fuels. By comparing different codes, the Expert Group on Advanced Fuel Cycle Scenarios is aiming at gaining further understanding of the scientific issues and specific national needs associated with the implementation of advanced fuel cycles. At the back end of the fuel cycle, separation technologies (aqueous and pyrochemical processing) are being assessed. Current and future activities comprise studies on minor actinides separation and post Fukushima studies. Regular workshops are also organized to discuss recent developments on Partitioning and Transmutation. In addition, the Nuclear Development Committee (NDC) focuses on the analysis of the economics of nuclear power across the fuel cycle in the context of changes of electricity markets, social acceptance and technological advances and assesses the availability of the nuclear fuel and infrastructure required for the deployment of existing and future nuclear power. The Expert Group on the Economics of the Back End of the Nuclear Fuel Cycle (EBENFC), in particular, is looking at assessing economic and financial issues related to the long term management of spent nuclear fuel. (authors)

  13. The effect of cadence on timing of muscle activation and mechanical output in cycling: on the activation dynamics hypothesis.

    PubMed

    McGhie, David; Ettema, Gertjan

    2011-02-01

    The purpose of this study was to examine the activation dynamics hypothesis, which states that, in cycling, the pattern between muscle activity and crank position shifts in regard to its angle in the crank cycle with increasing cadence to maintain invariant positioning of the mechanical output. We measured surface EMG of six muscles, and by means of force measurements at the crank and inverse dynamics calculated hip, knee, and ankle joint dynamics during cycling at five cadences (60-100 rpm) at 75% of maximal power in trained cyclists. The joint dynamics (net muscle moment and power) showed a consistent positive phase shift with increasing cadence. The phase shift in muscle activation patterns was highly variable amongst subjects and was, on average, close to zero. Our results are in contradiction with the activation dynamics hypothesis. PMID:20594872

  14. Finding year-long activity cycles in ground-based and space-borne photometry

    NASA Astrophysics Data System (ADS)

    Vida, Krisztián; Oláh, Katalin; Szabó, Róbert

    2015-08-01

    Using long­term ground­based photometry of fast­rotating M­-dwarfs (EY Dra, V405 And, GSC 3377­0296 and V374 Peg), all with rotational periods near 0.5 day, but with different internal structures, we found activity cycles in the form of long-­term brightness changes, on the time scales of about one year. Using the cycling stars as templates, we searched for similar, fast rotating (P < 1d), active, late­-type targets in the Kepler Input Catalogue. Analysing the light curves of these 39 stars, we found hints of 300­-900 day­-long cycles in 9 cases detecting small variations in the rotation periods caused by differential rotation and the changing spot emergence latitudes over the cycle (i.e., the butterfly diagram).

  15. Mechanisms for Diurnal Variability of Global Tropical Rainfall Observed from TRMM

    NASA Technical Reports Server (NTRS)

    Yang, Song; Smith, Eric A.

    2004-01-01

    The behavior and various controls of diurnal variability in tropical-subtropical rainfall are investigated using Tropical Rainfall Measuring Mission (TRMM) precipitation measurements retrieved from: (1) TRMM Microwave Imager (TMI), (2) Precipitation Radar (PR), and (3) TMI/PR Combined, standard level 2 algorithms for the 1998 annual cycle. Results show that the diurnal variability characteristics of precipitation are consistent for all three algorithms, providing assurance that TRMM retrievals are providing consistent estimates of rainfall variability. As anticipated, most ocean areas exhibit more rainfall at night, while over most land areas rainfall peaks during daytime ,however, various important exceptions are found. The dominant feature of the oceanic diurnal cycle is a rainfall maximum in late-evening/early-morning (LE-EM) hours, while over land the dominant maximum occurs in the mid- to late-afternoon (MLA). In conjunction with these maxima are pronounced seasonal variations of the diurnal amplitudes. Amplitude analysis shows that the diurnal pattern and its seasonal evolution are closely related to the rainfall accumulation pattern and its seasonal evolution. In addition, the horizontal distribution of diurnal variability indicates that for oceanic rainfall there is a secondary MLA maximum, co-existing with the LE-EM maximum, at latitudes dominated by large scale convergence and deep convection. Analogously, there is a preponderance for an LE-EM maximum over land, co-existing with the stronger MLA maximum, although it is not evident that this secondary continental feature is closely associated with the large scale circulation. The ocean results clearly indicate that rainfall diurnal variability associated with large scale convection is an integral part of the atmospheric general circulation.

  16. The solar cycle variation of the rates of CMEs and related activity

    NASA Technical Reports Server (NTRS)

    Webb, David F.

    1991-01-01

    Coronal mass ejections (CMEs) are an important aspect of the physics of the corona and heliosphere. This paper presents results of a study of occurrence frequencies of CMEs and related activity tracers over more than a complete solar activity cycle. To properly estimate occurrence rates, observed CME rates must be corrected for instrument duty cycles, detection efficiencies away from the skyplane, mass detection thresholds, and geometrical considerations. These corrections are evaluated using CME data from 1976-1989 obtained with the Skylab, SMM and SOLWIND coronagraphs and the Helios-2 photometers. The major results are: (1) the occurrence rate of CMEs tends to track the activity cycle in both amplitude and phase; (2) the corrected rates from different instruments are reasonably consistent; and (3) over the long term, no one class of solar activity tracer is better correlated with CME rate than any other (with the possible exception of type II bursts).

  17. Seasonal and diurnal patterns in the dispersion of SO2 from Mt. Nyiragongo

    NASA Astrophysics Data System (ADS)

    Dingwell, Adam; Rutgersson, Anna; Claremar, Björn; Arellano, Santiago; Yalire, Mathieu M.; Galle, Bo

    2016-05-01

    Mt. Nyiragongo is an active volcano located in the Democratic Republic of Congo, close to the border of Rwanda and about 15 km north of the city of Goma (∼ 1,000,000 inhabitants). Gases emitted from Nyiragongo might pose a persistent hazard to local inhabitants and the environment. While both ground- and satellite-based observations of the emissions exist, prior to this study, no detailed analysis of the dispersion of the emissions have been made. We have conducted a dispersion study, using a modelling system to determine the geographical distribution of SO2. A combination of a meteorological model (WRF), a Lagrangian particle dispersion model (FLEXPART-WRF) and flux data based on DOAS measurements from the NOVAC-network is used. Since observations can only be made during the day, we use random sampling of fluxes and ensemble modelling to estimate night-time emissions. Seasonal variations in the dispersion follows the migration of the Inter Tropical Convergence Zone. In June-August, the area with the highest surface concentrations is located to the northwest, and in December-February, to the southwest of the source. Diurnal variations in surface concentrations were determined by the development of the planetary boundary layer and the lake-/land breeze cycle around lake Kivu. Both processes contribute to low surface concentrations during the day and high concentrations during the night. However, the strong northerly trade winds in November-March weakened the lake breeze, contributing to higher daytime surface concentrations along the northern shore of Lake Kivu, including the city of Goma. For further analysis and measurements, it is important to include both seasonal and diurnal cycles in order to safely cover periods of high and potentially hazardous concentrations.

  18. Seasonal and diurnal patterns in the dispersion of SO2 from Mt. Nyiragongo

    NASA Astrophysics Data System (ADS)

    Dingwell, Adam; Rutgersson, Anna; Claremar, Björn; Arellano, Santiago; Yalire, Mathieu M.; Galle, Bo

    2016-05-01

    Mt. Nyiragongo is an active volcano located in the Democratic Republic of Congo, close to the border of Rwanda and about 15 km north of the city of Goma (∼ 1,000,000 inhabitants). Gases emitted from Nyiragongo might pose a persistent hazard to local inhabitants and the environment. While both ground- and satellite-based observations of the emissions exist, prior to this study, no detailed analysis of the dispersion of the emissions have been made. We have conducted a dispersion study, using a modelling system to determine the geographical distribution of SO2. A combination of a meteorological model (WRF), a Lagrangian particle dispersion model (FLEXPART-WRF) and flux data based on DOAS measurements from the NOVAC-network is used. Since observations can only be made during the day, we use random sampling of fluxes and ensemble modelling to estimate night-time emissions. Seasonal variations in the dispersion follows the migration of the Inter Tropical Convergence Zone. In June-August, the area with the highest surface concentrations is located to the northwest, and in December-February, to the southwest of the source. Diurnal variations in surface concentrations were determined by the development of the planetary boundary layer and the lake-/land breeze cycle around lake Kivu. Both processes contribute to low surface concentrations during the day and high concentrations during the night. However, the strong northerly trade winds in November-March weakened the lake breeze, contributing to higher daytime surface concentrations along the northern shore of Lake Kivu, including the city of Goma. For further analysis and measurements, it is important to include both seasonal and diurnal cycles in order to safely cover periods of high and potentially hazardous concentrations.

  19. Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific

    NASA Astrophysics Data System (ADS)

    Schuback, Nina; Flecken, Mirkko; Maldonado, Maria T.; Tortell, Philippe D.

    2016-02-01

    Active chlorophyll a fluorescence approaches, including fast repetition rate fluorometry (FRRF), have the potential to provide estimates of phytoplankton primary productivity at an unprecedented spatial and temporal resolution. FRRF-derived productivity rates are based on estimates of charge separation in reaction center II (ETRRCII), which must be converted into ecologically relevant units of carbon fixation. Understanding sources of variability in the coupling of ETRRCII and carbon fixation provides physiological insight into phytoplankton photosynthesis and is critical for the application of FRRF as a primary productivity measurement tool. In the present study, we simultaneously measured phytoplankton carbon fixation and ETRRCII in the iron-limited NE subarctic Pacific over the course of a diurnal cycle. We show that rates of ETRRCII are closely tied to the diurnal cycle in light availability, whereas rates of carbon fixation appear to be influenced by endogenous changes in metabolic energy allocation under iron-limited conditions. Unsynchronized diurnal oscillations of the two rates led to 3.5-fold changes in the conversion factor between ETRRCII and carbon fixation (Kc / nPSII). Consequently, diurnal variability in phytoplankton carbon fixation cannot be adequately captured with FRRF approaches if a constant conversion factor is applied. Utilizing several auxiliary photophysiological measurements, we observed that a high conversion factor is associated with conditions of excess light and correlates with the increased expression of non-photochemical quenching (NPQ) in the pigment antenna, as derived from FRRF measurements. The observed correlation between NPQ and Kc / nPSII requires further validation but has the potential to improve estimates of phytoplankton carbon fixation rates from FRRF measurements alone.

  20. Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific

    NASA Astrophysics Data System (ADS)

    Schuback, N.; Flecken, M.; Maldonado, M. T.; Tortell, P. D.

    2015-10-01

    Active chlorophyll a fluorescence approaches, including fast repetition rate fluorometry (FRRF), have the potential to provide estimates of phytoplankton primary productivity at unprecedented spatial and temporal resolution. FRRF-derived productivity rates are based on estimates of charge separation at PSII (ETRRCII), which must be converted into ecologically relevant units of carbon fixation. Understanding sources of variability in the coupling of ETRRCII and carbon fixation provides physiological insight into phytoplankton photosynthesis, and is critical for the application of FRRF as a primary productivity measurement tool. In the present study, we simultaneously measured phytoplankton carbon fixation and ETRRCII in the iron-limited NE subarctic Pacific, over the course of a diurnal cycle. We show that rates of ETRRCII are closely tied to the diurnal cycle in light availability, whereas rates of carbon fixation appear to be influenced by endogenous changes in metabolic energy allocation under iron-limited conditions. Unsynchronized diurnal oscillations of the two rates led to 3.5 fold changes in the conversion factor coupling ETRRCII and carbon fixation (Φe:C / nPSII). Consequently, diurnal variability in phytoplankton carbon fixation cannot be adequately captured with FRRF approaches if a constant conversion factor is applied. Utilizing several auxiliary photophysiological measurements, we observed that a high conversion factor is associated with conditions of excess light, and correlates with the expression of non-photochemical quenching (NPQ) in the pigment antenna, as derived from FRRF measurements. The observed correlation between NPQ and the conversion factor Φe:C / nPSII has the potential to improve estimates of phytoplankton carbon fixation rates from FRRF measurements alone.

  1. Diurnal Variations of Meteoric Fe Layers in the Mesosphere and Lower Thermosphere at McMurdo (77.8°S, 166.7°E), Antarctica

    NASA Astrophysics Data System (ADS)

    Yu, Z.; Chu, X.; Huang, W.; Fong, W.

    2011-12-01

    As one of the main metal species in the mesosphere and lower thermosphere, neutral Fe layers provide an excellent tracer for studying atmospheric dynamics and chemistry. Unfortunately, most Fe measurements were made in the night, except a few reports from the Antarctic and Arctic. So far studies of the diurnal variations of Fe layers are very rare. This situation poses interesting questions like how Fe layers vary through a diurnal cycle, whether such variations change with seasons, and what mechanisms contribute to the diurnal variations. To help address this issue, we report the diurnal variations of Fe densities, based on our lidar observations made at McMurdo, Antarctica. The data were collected with an Fe Boltzmann lidar since late December 2010 through austral autumn, winter and spring in 2011, covering the states of polar days under full sunlight, alternations between day and night, and polar nights under total darkness. By taking composite days, we obtain 24-h Fe coverage for every month, allowing relatively detailed study of the diurnal variations. Our preliminary analyses show an interesting phenomenon that the bottom boundary of Fe layers extends downward from ~80 km to ~75 km or lower when switching from night to day. This phenomenon is obvious in continuous (straight) 24-h data as well as in composite 24-h data during March and April when the sunlight conditions have day and night switches. The results indicate that photochemistry, rather than wave dynamics, may play an essential role in determining the Fe layer bottom. No obvious diurnal variations are observed in polar summer and mid-winter; however, the layer bottom altitude descends for several kilometers from polar day to polar night. These likely reflect the influences of temperatures, waves, mesospheric clouds and aurora activities.

  2. Relationship between skin temperature and muscle activation during incremental cycle exercise.

    PubMed

    Priego Quesada, Jose I; Carpes, Felipe P; Bini, Rodrigo R; Salvador Palmer, Rosario; Pérez-Soriano, Pedro; Cibrián Ortiz de Anda, Rosa M

    2015-02-01

    While different studies showed that better fitness level adds to the efficiency of the thermoregulatory system, the relationship between muscular effort and skin temperature is still unknown. Therefore, the present study assessed the relationship between neuromuscular activation and skin temperature during cycle exercise. Ten physically active participants performed an incremental workload cycling test to exhaustion while neuromuscular activations were recorded (via surface electromyography - EMG) from rectus femoris, vastus lateralis, biceps femoris and gastrocnemius medialis. Thermographic images were recorded before, immediately after and 10 min after finishing the cycling test, at four body regions of interest corresponding to the muscles where neuromuscular activations were monitored. Frequency band analysis was conducted to assess spectral properties of EMG signals in order to infer on priority in recruitment of motor units. Significant inverse relationship between changes in skin temperature and changes in overall neuromuscular activation for vastus lateralis was observed (r<-0.5 and p<0.04). Significant positive relationship was observed between skin temperature and low frequency components of neuromuscular activation from vastus lateralis (r>0.7 and p<0.01). Participants with larger overall activation and reduced low frequency component for vastus lateralis activation presented a better adaptive response of their thermoregulatory system by showing fewer changes in skin temperature after incremental cycling test. PMID:25660627

  3. A Comparison Between Global Proxies of the Sun's Magnetic Activity Cycle: Inferences from Helioseismology

    NASA Astrophysics Data System (ADS)

    Broomhall, A.-M.; Nakariakov, V. M.

    2015-11-01

    The last solar minimum was, by recent standards, unusually deep and long. We are now close to the maximum of the subsequent solar cycle, which is relatively weak. In this article we make comparisons between different global (unresolved) measures of the Sun's magnetic activity to investigate how they are responding to this weak-activity epoch. We focus on helioseismic data, which are sensitive to conditions, including the characteristics of the magnetic field, in the solar interior. Also considered are measures of the magnetic field in the photosphere (sunspot number and sunspot area), the chromosphere and corona (10.7 cm radio flux and 530.3 nm green coronal index), and two measures of the Sun's magnetic activity closer to Earth (the interplanetary magnetic field and the galactic cosmic-ray intensity). Scaled versions of the activity proxies diverge from the helioseismic data around 2000, indicating a change in relationship between the proxies. The degree of divergence varies from proxy to proxy, with sunspot area and 10.7 cm flux showing only small deviations, while sunspot number, coronal index, and the two interplanetary proxies show much larger departures. In Cycle 24 the deviations in the solar proxies and the helioseismic data decrease, raising the possibility that the deviations observed in Cycle 23 are just symptomatic of a 22-year Hale cycle. However, the deviations in the helioseismic data and the interplanetary proxies increase in Cycle 24. Interestingly, the divergence in the solar proxies and the helioseismic data are not reflected in the shorter-term variations (often referred to as quasi-biennial oscillations) observed on top of the dominant 11-year solar cycle. However, despite being highly correlated in Cycle 22, the short-term variations in the interplanetary proxies show very little correlation with the helioseismic data during Cycles 23 and 24.

  4. Diurnal changes in epidermal UV transmittance of plants in naturally high UV environments.

    PubMed

    Barnes, Paul W; Flint, Stephan D; Slusser, James R; Gao, Wei; Ryel, Ronald J

    2008-06-01

    Studies were conducted on three herbaceous plant species growing in naturally high solar UV environments in the subalpine of Mauna Kea, Hawaii, USA, to determine if diurnal changes in epidermal UV transmittance (T(UV)) occur in these species, and to test whether manipulation of the solar radiation regime could alter these diurnal patterns. Additional field studies were conducted at Logan, Utah, USA, to determine if solar UV was causing diurnal T(UV) changes and to evaluate the relationship between diurnal changes in T(UV) and UV-absorbing pigments. Under clear skies, T(UV), as measured with a UV-A-pulse amplitude modulation fluorometer for leaves of Verbascum thapsus and Oenothera stricta growing in native soils and Vicia faba growing in pots, was highest at predawn and sunset and lowest at midday. These patterns in T(UV) closely tracked diurnal changes in solar radiation and were the result of correlated changes in fluorescence induced by UV-A and blue radiation but not photochemical efficiency (F(v)/F(m)) or initial fluorescence yield (F(o)). The magnitude of the midday reduction in T(UV) was greater for young leaves than for older leaves of Verbascum. Imposition of artificial shade eliminated the diurnal changes in T(UV) in Verbascum, but reduction in solar UV had no effect on diurnal T(UV) changes in Vicia. In Vicia, the diurnal changes in T(UV) occurred without detectable changes in the concentration of whole-leaf UV-absorbing compounds. Results suggest that plants actively control diurnal changes in UV shielding, and these changes occur in response to signals other than solar UV; however, the underlying mechanisms responsible for rapid changes in T(UV) remain unclear. PMID:18346077

  5. Body temperature and physical activity correlates of the menstrual cycle in Chacma Baboons (Papio hamadryas ursinus).

    PubMed

    Nyakudya, Trevor T; Fuller, Andrea; Meyer, Leith C R; Maloney, Shane K; Mitchell, Duncan

    2012-12-01

    We investigated the temporal relationship between abdominal temperature, physical activity, perineal swelling, and urinary progesterone and estradiol concentrations over the menstrual cycle in unrestrained captive baboons. Using a miniature temperature-sensitive data logger surgically implanted in the abdominal cavity and an activity data logger implanted subcutaneously on the trunk, we measured, continuously over 6 months at 10-min intervals, abdominal temperature and physical activity patterns in four female adult baboons Papio hamadryas ursinus (12.9-19.9 kg), in cages in an indoor animal facility (22-25°C). We monitored menstrual bleeding and perineal swelling changes, and measured urinary progesterone and estradiol concentrations, daily for up to 6 months, to ascertain the stage and length of the menstrual cycle. The menstrual cycle was 36 ± 2 days (mean ± SD) long and the baboons exhibited cyclic changes in perineal swellings, abdominal temperature, physical activity, urinary progesterone, and estradiol concentrations over the cycle. Mean 24-hr abdominal temperature during the luteal phase was significantly higher than during the periovulatory phase (ANOVA, F((2, 9)) = 4.7; P = 0.04), but not different to that during the proliferative phase. Physical activity followed a similar pattern, with mean 24-hr physical activity almost twice as high in the luteal than in the periovulatory phase (ANOVA, P = 0.58; F((2, 12)) = 5.8). We have characterized correlates of the menstrual cycle in baboons and shown, for the first time, a rhythm of physical activity and abdominal temperature over the menstrual cycle, with a nadir of temperature and activity at ovulation. PMID:22930453

  6. The effects of feedback lighting on the circadian drinking rhythm in the diurnal new world primate Saimiri sciureus

    NASA Technical Reports Server (NTRS)

    Ferraro, J. S.; Sulzman, F. M.

    1988-01-01

    Feedback lighting provides illumination primarily during the subjective night (i.e., the photosensitive portion of the circadian cycle) in response to a given behavior. This technique has previously been used to test the nonparametric model of entrainment in nocturnal rodents. In three species (Rattus norvegicus, Mesocricetus auratus, and Mus musculus), the free-running period of the locomotor activity rhythm was similar whether the animals were exposed to continuous light or discrete light pulses occurring essentially only during the subjective night (i.e., feedback lighting). In the current experiments, feedback lighting was presented to squirrel monkeys so that light fell predominantly during the subjective night. Feedback lighting was linked to the drinking behavior in this diurnal primate so that when the animal drank, the lights went out. Despite the seemingly adverse predicament, the monkeys maintained regular circadian drinking rhythms. Furthermore, just as the period of the free-running activity rhythms of nocturnal rodents exposed to continuous light or feedback lighting were similar, the period of the drinking rhythms of the squirrel monkeys in continuous light and feedback lighting were comparable (25.6 +/- 0.1 and 25.9 +/- 0.1 hours, respectively), despite a substantial decrease in the total amount of light exposure associated with feedback lighting. The free-running period of monkeys exposed to continuous dark (24.5 +/- 0.1 hours) was significantly shorter than either of the two lighting conditions (P < 0.001). The results presented for the drinking rhythm were confirmed by examination of the temperature and activity rhythms. Therefore, discrete light pulses given predominately during the subjective night are capable of simulating the effects of continuous light on the free-running period of the circadian rhythms of a diurnal primate. The response of squirrel monkeys to feedback lighting thus lends further support for the model and suggests that the

  7. Tubulin dynamics during the cytoplasmic cohesiveness cycle in artificially activated sea urchin eggs.

    PubMed

    Coffe, G; Foucault, G; Raymond, M N; Pudles, J

    1983-12-01

    Sedimentation studies and [3H]colchicine-binding assays have demonstrated a relationship between the cytoplasmic cohesiveness cycles and the changes in tubulin organization in Paracentrotus lividus eggs activated by 2.5 mM procaine. The same amount of tubulin (20-25% of the total egg tubulin) is involved in these cyclic process and appears to undergo polymerization and depolymerization cycles. Electron microscopy studies reveal that the microtubules formed during these cytoplasmic cohesiveness cycles are under a particulate form which is sedimentable at low speed. Activation experiments carried out in the presence of cytochalasin B (CB) show that the increase in the cytoplasmic cohesiveness is highly reduced while tubulin polymerization and depolymerization cycles and pronuclear centration are not affected. Although tubulin or actin polymerization can be independently triggered in procaine-activated eggs, the increase in cytoplasmic cohesiveness requires the polymerization of both proteins. However, the cytoplasmic cohesiveness cycles appear to be regulated by tubulin polymerization and depolymerization cycles. PMID:6641809

  8. Discovery of an activity cycle in the solar analog HD 45184. Exploring Balmer and metallic lines as activity proxy candidates

    NASA Astrophysics Data System (ADS)

    Flores, M.; González, J. F.; Jaque Arancibia, M.; Buccino, A.; Saffe, C.

    2016-05-01

    Context. Most stellar activity cycles similar to that found in the Sun have been detected by using the chromospheric Ca ii H&K lines as stellar activity proxies. However, it is unclear whether such activity cycles can be identified using other optical lines. Aims: We aim to detect activity cycles in solar-analog stars and determine whether they can be identified through other optical lines, such as Fe II and Balmer lines. We study the solar-analog star HD 45184 using HARPS spectra. The temporal coverage and high quality of the spectra allow us to detect both long- and short-term activity variations. Methods: We analysed the activity signatures of HD 45184 by using 291 HARPS spectra obtained between 2003 and 2014. To search for line-core flux variations, we focused on Ca ii H&K and Balmer Hα and Hβ lines, which are typically used as optical chromospheric activity indicators. We calculated the HARPS-S index from Ca ii H&K lines and converted it into the Mount Wilson scale. In addition, we also considered the equivalent widths of Balmer lines as activity indicators. Moreover, we analysed the possible variability of Fe ii and other metallic lines in the optical spectra. The spectral variations were analysed for periodicity using the Lomb-Scargle periodogram. Results: We report for the first time a long-term 5.14-yr activity cycle in the solar-analog star HD 45184 derived from Mount Wilson S index. This makes HD 45184 one of most similar stars to the Sun with a known activity cycle. The variation is also evident in the first lines of the Balmer series, which do not always show a correlation with activity in solar-type stars. Notably, unlike the solar case, we also found that the equivalent widths of the high photospheric Fe ii lines (4924 Å, 5018 Å and 5169 Å) are modulated (±2 mÅ) by the chromospheric cycle of the star. These metallic lines show variations above 4σ in the rms spectrum, while some Ba ii and Ti ii lines present variations at 3σ level, which

  9. Central melanopsin projections in the diurnal rodent, Arvicanthis niloticus

    PubMed Central

    Langel, Jennifer L.; Smale, Laura; Esquiva, Gema; Hannibal, Jens

    2015-01-01

    The direct effects of photic stimuli on behavior are very different in diurnal and nocturnal species, as light stimulates an increase in activity in the former and a decrease in the latter. Studies of nocturnal mice have implicated a select population of retinal ganglion cells that are intrinsically photosensitive (ipRGCs) in mediation of these acute responses to light. ipRGCs are photosensitive due to the expression of the photopigment melanopsin; these cells use glutamate and pituitary adenylate cyclase-activating polypeptide (PACAP) as neurotransmitters. PACAP is useful for the study of central ipRGC projections because, in the retina, it is found exclusively within melanopsin cells. Little is known about the central projections of ipRGCs in diurnal species. Here, we first characterized these cells in the retina of the diurnal Nile grass rat using immunohistochemistry (IHC). The same basic subtypes of melanopsin cells that have been described in other mammals were present, but nearly 25% of them were displaced, primarily in its superior region. PACAP was present in 87.7% of all melanopsin cells, while 97.4% of PACAP cells contained melanopsin. We then investigated central projections of ipRGCs by examining the distribution of immunoreactive PACAP fibers in intact and enucleated animals. This revealed evidence that these cells project to the suprachiasmatic nucleus, lateral geniculate nucleus (LGN), pretectum, and superior colliculus. This distribution was confirmed with injections of cholera toxin subunit β coupled with Alexa Fluor 488 in one eye and Alexa Fluor 594 in the other, combined with IHC staining of PACAP. These studies also revealed that the ventral and dorsal LGN and the caudal olivary pretectal nucleus receive less innervation from ipRGCs than that reported in nocturnal rodents. Overall, these data suggest that although ipRGCs and their projections are very similar in diurnal and nocturnal rodents, they may not be identical. PMID:26236201

  10. Sex-dependent activity of the spinal excitatory amino acid transporter: Role of estrous cycle.

    PubMed

    Sajjad, Jahangir; Felice, Valeria D; Golubeva, Anna V; Cryan, John F; O'Mahony, Siobhain M

    2016-10-01

    Females are more likely to experience visceral pain than males, yet mechanisms underlying this sex bias are not fully elucidated. Moreover, pain sensitivity can change throughout the menstrual cycle. Alterations in the glutamatergic system have been implicated in several pain-disorders; however, whether these are sex-dependent is unclear. Thus, we aimed to investigate sex differences in the spinal cord glutamate uptake and how it varies across the estrous cycle. The activity of the glutamate transporters, excitatory amino acid transporters (EAATs) was assessed using an ex vivo aspartate radioactive uptake assay in the lumbosacral spinal cord in Sprague-Dawley male and female rats. The gene expression of EAATs, glutamate receptor subunits NR1 and NR2B and the estrogen receptors ERα & ERβ in the spinal cord were also analyzed. EAAT activity was lower in females, particularly during the estrus phase, and this was the only cycle stage that was responsive to the pharmacological effects of the EAATs activator riluzole. Interestingly, EAAT1 mRNA expression was lower in high-estrogen and high-ERα states compared to diestrus in females. We conclude that the Spinal EAAT activity in females is different to that in males, and varies across the estrous cycle. Furthermore, the expression levels of estrogen receptors also showed a cycle-dependent pattern that may affect EAATs function and expression. PMID:27471194

  11. Restraint stress delays reentrainment in male and female diurnal and nocturnal rodents.

    PubMed

    Mohawk, Jennifer A; Lee, Theresa M

    2005-06-01

    A temporary loss of normal circadian entrainment, such as that associated with shift work and transmeridian travel, can result in an array of detrimental symptoms, making rapid reentrainment of rhythmicity essential. While there is a wealth of literature examining the effects of stress on the entrained circadian system, less is known about the influence of stress on circadian function following a phase shift of the light: dark (LD) cycle. The authors find that recovery of locomotor activity synchronization is altered by restraint stress in the diurnal rodent Octodon degus (degu) and the nocturnal rat. In the first experiment, degus were subjected to a 6-h phase advance of the LD cycle. Sixty minutes after the new lights-on, animals underwent 60 min of restraint stress. The number of days it took each animal to reentrain its activity rhythms to the new LD cycle was recorded and compared to the number of days it took the animal to reentrain under control conditions. When subjected to restraint stress, degus took 30% longer to reentrain their activity rhythms (p < 0.01). In a second experiment, rats underwent a similar experimental paradigm. As with the degus, stress significantly delayed the reentrainment of rats' activity rhythms (p < 0.01). There was no interaction between sex and stress on the rate of reentrainment for either rats or degus. Furthermore, there was no effect of stress on the free-running activity rhythm of degus, suggesting that the effect of stress on reentrainment rate is not secondary to alterations of period length. Together, these data point to a detrimental effect of stress on recovery of entrainment of circadian rhythms, which is independent of activity niche and sex. PMID:15851531

  12. Diurnal and Seasonal Change in Stem Respiration of Larix principis-rupprechtii Trees, Northern China

    PubMed Central

    Yang, Yan; Zhao, Miao; Xu, Xiangtao; Sun, Zhenzhong; Yin, Guodong; Piao, Shilong

    2014-01-01

    Stem respiration is a critical and uncertain component of ecosystem carbon cycle. Few studies reported diurnal change in stem respiration as well as its linkage with climate. In this study, we investigated the diurnal and seasonal change in stem respiration and its linkage with environmental factors, in larch plantations of northern China from 2010 to 2012. The stem respiration per unit surface area (RS) showed clear diurnal cycles, ranging from 1.65±0.10 to 2.69±0.15 µmol m−2 s−1, increased after 6∶00, peaked at 15∶00 and then decreased. Both stem temperature and air temperature show similar diurnal pattern, while the diurnal pattern of air relative humidity is just the opposite to Rs. Similar to the diurnal cycles, seasonal change in RS followed the pattern of stem temperature. RS increased from May (1.28±0.07 µmol m−2 s−1) when the stem temperature was relatively low and peaked in July (3.02±0.10 µmol m−2 s−1) when the stem temperature was also the highest. Further regression analyses show that RS exponentially increases with increasing temperature, and the Q10 of Rs at mid daytime (1.97±0.17 at 12∶00 and 1.96±0.10 at 15∶00) is significantly lower than that of mid nighttime (2.60±0.14 at 00∶00 and 2.71±0.25 at 03∶00) Q10. This result not only implies that Rs is more sensitive to night than day warming, but also highlights that temperature responses of Rs estimated by only daytime measurement can lead to underestimated stem respiration increase under global warming, especially considering that temperature increase is faster during nighttime. PMID:24586668

  13. Reconstruction of geomagnetic activity and near-Earth interplanetary conditions over the past 167 yr - Part 3: Improved representation of solar cycle 11

    NASA Astrophysics Data System (ADS)

    Lockwood, M.; Nevanlinna, H.; Vokhmyanin, M.; Ponyavin, D.; Sokolov, S.; Barnard, L.; Owens, M. J.; Harrison, R. G.; Rouillard, A. P.; Scott, C. J.

    2014-04-01

    Svalgaard (2014) has recently pointed out that the calibration of the Helsinki magnetic observatory's H component variometer was probably in error in published data for the years 1866-1874.5 and that this makes the interdiurnal variation index based on daily means, IDV(1d), (Lockwood et al., 2013a), and the interplanetary magnetic field strength derived from it (Lockwood et al., 2013b), too low around the peak of solar cycle 11. We use data from the modern Nurmijarvi station, relatively close to the site of the original Helsinki Observatory, to confirm a 30% underestimation in this interval and hence our results are fully consistent with the correction derived by Svalgaard. We show that the best method for recalibration uses the Helsinki Ak (H) and aa indices and is accurate to ±10%. This makes it preferable to recalibration using either the sunspot number or the diurnal range of geomagnetic activity which we find to be accurate to ±20%. In the case of Helsinki data during cycle 11, the two recalibration methods produce very similar corrections which are here confirmed using newly digitised data from the nearby St Petersburg observatory and also using declination data from Helsinki. However, we show that the IDV index is, compared to later years, too similar to sunspot number before 1872, revealing independence of the two data series has been lost; either because the geomagnetic data used to compile IDV has been corrected using sunspot numbers, or vice versa, or both. We present corrected data sequences for both the IDV(1d) index and the reconstructed IMF (interplanetary magnetic field). We also analyse the relationship between the derived near-Earth IMF and the sunspot number and point out the relevance of the prior history of solar activity, in addition to the contemporaneous value, to estimating any "floor" value of the near-Earth interplanetary field.

  14. Low-intensity cycling affects the muscle activation pattern of consequent countermovement jumps.

    PubMed

    Marquez, Gonzalo J; Mon, Javier; Acero, Rafael M; Sanchez, Jose A; Fernandez-del-Olmo, Miguel

    2009-08-01

    Players (eg, basketball, soccer, and football) often use a static bicycle during a game to maintain warming. However, the effectiveness of this procedure has not been addressed in the literature. Thus, it remains unknown whether low-intensity cycling movement can affect explosive movement performance. In this study, 10 male subjects performed countermovement jumps before and after a 15-minutes cycling bout at 35% of their maximal power output. Three sessions were tested for 3 different cadences of cycling: freely chosen cadence, 20% lower than freely chosen cadence (FCC-20%), and 20% higher than freely chosen cadence (FCC+20%). Jump height, kinematics, and electromyogram were recorded simultaneously during the countermovement jumps. The results showed a significant decreasing in the height of countermovement jump after cycling at freely chosen cadence and FCC-20% (p = 0.03 and p = 0.04, respectively), but not for FCC+20% cadences. The electromyographic parameters suggest that changes in the countermovement jump after cycling can be attributed to alteration of the pattern of activation and may be modulated by the preceding cycling cadence. Our study indicates that to avoid a possible negative effect of the cycling in the subsequent explosive movements, a cadence 20% higher than the preferred cadence must be used. PMID:19620918

  15. The effect of physical activity across the menstrual cycle on reproductive function

    PubMed Central

    Ahrens, Katherine A.; Vladutiu, Catherine J.; Mumford, Sunni L.; Schliep, Karen C.; Perkins, Neil J.; Wactawski-Wende, Jean; Schisterman, Enrique F.

    2013-01-01

    Purpose To evaluate the association between physical activity (PA) across the menstrual cycle and reproductive function. Methods The BioCycle Study (2005–2007) followed 259, healthy premenopausal women not using hormonal contraceptives for up to two menstrual cycles (N=509 cycles). Serum leptin, estradiol, progesterone, luteinizing hormone, follicle-stimulating hormone, and testosterone were measured five to eight times per cycle. Linear mixed models were used to estimate the effect of past-week PA (measured four times during each cycle) on hormone levels. Past-week PA was categorized into tertiles based on metabolic equivalent [MET]-h/week (cut-points were 15.3 and 35.7). Risk ratios for sporadic anovulation were estimated using generalized linear models. Analyses adjusted for habitual PA (assessed at baseline), body mass index, race, age, and perceived stress. Linear mixed models used inverse probability weights to control for concurrent reproductive hormones and caloric intake. Results High past-week PA was inversely associated with leptin (−6.6%, 95% confidence interval [−10.6, −2.5]) and luteal phase progesterone (−22.1% [−36.2, −4.7]) as compared with low past-week PA. High past-week PA was not significantly associated with sporadic anovulation (adjusted risk ratio=1.5 [0.6, 3.4]). Conclusions High levels of PA were modestly associated with changes in select hormones, but not sporadic anovulation among moderate to highly active premenopausal women. PMID:24345590

  16. Levetiracetam: Probably Associated Diurnal Frequent Urination.

    PubMed

    Ju, Jun; Zou, Li-Ping; Shi, Xiu-Yu; Hu, Lin-Yan; Pang, Ling-Yu

    2016-01-01

    Diurnal frequent urination is a common condition in elementary school children who are especially at risk for associated somatic and behavioral problems. Levetiracetam (LEV) is a broad-spectrum antiepileptic drug that has been used in both partial and generalized seizures and less commonly adverse effects including psychiatric and behavioral problems. Diurnal frequent urination is not a well-known adverse effect of LEV. Here, we reported 2 pediatric cases with epilepsy that developed diurnal frequent urination after LEV administration. Case 1 was a 6-year-old male patient who presented urinary frequency and urgency in the daytime since the third day after LEV was given as adjunctive therapy. Symptoms increased accompanied by the raised dosage of LEV. Laboratory tests and auxiliary examinations did not found evidence of organic disease. Diurnal frequent urination due to LEV was suspected, and then the drug was discontinued. As expected, his frequency of urination returned to normal levels. Another 13-year-old female patient got similar clinical manifestations after oral LEV monotherapy and the symptoms became aggravated while in stress state. Since the most common causes of frequent micturition had been ruled out, the patient was considered to be diagnosed with LEV-associated psychogenic frequent urination. The dosage of LEV was reduced to one-third, and the frequency of urination was reduced by 60%. Both patients got the Naranjo score of 6, which indicated that LEV was a "probable" cause of diurnal frequent urination. Although a definite causal link between LEV and diurnal urinary frequency in the 2 cases remains to be established, we argue that diurnal frequent urination associated with LEV deserves clinician's attention. PMID:26938751

  17. Sensitivity of Initial Conditions on Diurnal Variability of Indian Summer Monsoon

    NASA Astrophysics Data System (ADS)

    Das, Sukanta Kumar; Deb, Sanjib Kumar; Kishtawal, C. M.; Pal, Pradip Kumar

    2015-10-01

    The diurnal cycle of different surface parameters, viz. surface air temperature, surface pressure, and rain intensities, simulated by the Community Atmosphere Model (CAM) in the operational seasonal forecast of ISM-2012 using initial conditions (ICs) taken at synoptic hours of the day has been examined and compared with observations. Four members were simulated with ICs at 0000, 0600, 1200, and 1800 UTC on 1 August 2012. The impact of the initial conditions at the synoptic hours of the day was more visible over the landmass compared with the oceanic regions. The diurnal variation of the surface temperature in the model simulation showed the major features when compared with the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis except for the warm pool of northwest India and the Tibetan region. The surface pressure in the ECMWF reanalysis showed the semidiurnal cycle with two peaks at 0600 UTC and 1800 UTC; however, the range of the cycle was underestimated by the model simulation, showing only one peak at 0600 UTC. Significant variations in the diurnal cycle of rain intensities were seen among the different members. The model captured the diurnal cycle as the positive and negative peaks at 1200 and 0000 UTC with intensities at the peaks ~0.5 mm high and low, respectively, in the model simulation when compared with the observations. Presently, the seasonal forecast of ISM is generated through ensemble CAM experiments using different ICs taken from different dates but all at 0000 UTC. Consideration of ICs at different times of the day will add different ranges of diurnal variations in all the surface parameters within the family of ensemble members and also increase the number of members in the family. Indeed, these improve the ensemble processes in generating the seasonal forecast of ISM.

  18. Effects of physical activity on pupil cycle time (PCT) in healthy Indian male.

    PubMed

    Ghosh, Suparna; Avadhany, Sandhya T

    2014-01-01

    Globally, physical inactivity is an important risk factor for the development of non-communicable disease consisting of coronary artery disease, as well as, other diseases including hypertension, diabetes, obesity, osteoporosis, and certain types of cancers. Parasympathetic nervous system (PNS) activity in the eye is determined by the pupil cycle time (PCT) can be comparable with cardiac parasympathetic response and thereby determine the morbidity and mortality among individuals. The PCT is measured by throwing white light on the edge of the pupil. Pupil cycling is a feature of pupillary reflex arc. The aim of this study is to establish the effect of physical activity on the PCT. The counting of PCT was done for 90 cycles and average one count is considered a single PCT. The physical activity level (PAL) was determined by administering a physical activity level questionnaire developed in the Division of Nutrition, St. John's Medical College, Bangalore. The PAL is classified as < 1.4 as sedentary, 1.55 to 1.75 moderately active, and > 1.75 heavily active. Thirty healthy male volunteers in the age group of 18-50 years and with BMI of 18.5 kg/m2-30 kg/m2 were studied. We obtained PCT of 962.00 ± 105.72 msec in sedentary, 896.77 ± 85.88 msec in moderately active and 889.45 ± 68.71 msec in heavily active individuals. Linear regression analysis shows there is statistically significant difference between the three different groups of physical activity level with a b value of 0 and R2 being 0.19. Increase in physical activity led to decrease in the PCT i.e. increase in the parasympathetic tone in the eye. Pupil cycle time (PCT) is a simple noninvasive tool to assess and differentiate the PNS function in different activity level of individual. PMID:25906609

  19. Impact of New Transport Infrastructure on Walking, Cycling, and Physical Activity

    PubMed Central

    Panter, Jenna; Heinen, Eva; Mackett, Roger; Ogilvie, David

    2016-01-01

    Introduction Walking and cycling bring health and environmental benefits, but there is little robust evidence that changing the built environment promotes these activities in populations. This study evaluated the effects of new transport infrastructure on active commuting and physical activity. Study design Quasi-experimental analysis nested within a cohort study. Setting/participants Four hundred and sixty-nine adult commuters, recruited through a predominantly workplace-based strategy, who lived within 30 kilometers of Cambridge, United Kingdom and worked in areas of the city to be served by the new transport infrastructure. Intervention The Cambridgeshire Guided Busway opened in 2011 and comprised a new bus network and a traffic-free walking and cycling route. Exposure to the intervention was defined using the shortest distance from each participant’s home to the busway. Main outcome measures Change in weekly time spent in active commuting between 2009 and 2012, measured by validated 7-day recall instrument. Secondary outcomes were changes in total weekly time spent walking and cycling and in recreational and overall physical activity, measured using the validated Recent Physical Activity Questionnaire. Data were analyzed in 2014. Results In multivariable multinomial regression models—adjusted for potential sociodemographic, geographic, health, and workplace confounders; baseline active commuting; and home or work relocation—exposure to the busway was associated with a significantly greater likelihood of an increase in weekly cycle commuting time (relative risk ratio=1.34, 95% CI=1.03, 1.76) and with an increase in overall time spent in active commuting among the least active commuters at baseline (relative risk ratio=1.76, 95% CI=1.16, 2.67). The study found no evidence of changes in recreational or overall physical activity. Conclusions Providing new sustainable transport infrastructure was effective in promoting an increase in active commuting. These

  20. [The development of the activity-rest cycle in the rabbit fetus].

    PubMed

    Belich, A I; Nazarova, L A

    1988-01-01

    On 25-30-day rabbit foetuses, in chronic experiments using constant synchronous recording of the motor activity and heart rate, studies have been made of temporal organization of the activity-rest cycle. Already in 25-day foetus, three functional conditions may be distinguished: active, intermediate and resting ones, the duration of the latter increasing to the end of gestation up to 8-10 min, whereas the duration of the intermediate phase decreases, reaching its minimum to the 30th day if not being completely reduced. Cyclic pattern of active and resting phases is observed in 28-day foetuses; to the 29th-30th day, these phases from a unique activity-rest cycle, its duration reaching 20-30 min to the end of intrauterine period. It is suggested that the resting phase in foetal rabbits serves as a basis for the development of polyphasic sleep in adult animals. PMID:3414220