WorldWideScience

Sample records for dynamic seasonal variation

  1. Seasonal Variation in Epidemiology

    Science.gov (United States)

    Marrero, Osvaldo

    2013-01-01

    Seasonality analyses are important in medical research. If the incidence of a disease shows a seasonal pattern, then an environmental factor must be considered in its etiology. We discuss a method for the simultaneous analysis of seasonal variation in multiple groups. The nuts and bolts are explained using simple trigonometry, an elementary…

  2. Seasonal dynamics of insecticide resistance, multiple resistance, and morphometric variation in field populations of Culex pipiens.

    Science.gov (United States)

    Taskin, Belgin Gocmen; Dogaroglu, Taylan; Kilic, Sercan; Dogac, Ersin; Taskin, Vatan

    2016-05-01

    Resistance to insecticides that impairs nervous transmission has been widely investigated in mosquito populations as insecticides are crucial to effective insect control. The development of insecticide resistance is also of special interest to evolutionary biologists since it represents the opportunity to observe the genetic consequences of a well-characterized alteration in the environment. Although the frequencies of resistance alleles in Culex pipiens populations against different groups of insecticides have been reported, no detailed information is available on the relative change in these allele frequencies over time. In this study, we collected mosquitoes of the Cx. pipiens complex from six locations in three seasons in the Aegean region of Turkey and examined the i) seasonal variations in resistance to four different chemical classes of insecticides, ii) seasonal fluctuations in frequencies of resistance-associated target-site mutations of the three genes (ace-1, kdr, and Rdl), and iii) potential seasonal variations in wing morphometric characters that may be modified in resistant mosquitoes. Our bioassay results indicated the presence of different levels of resistance to all tested insecticides for all three seasons in all locations. The results of the PCR-based molecular analysis revealed low frequencies of mutations in ace-1 and Rdl that are associated with resistance to malathion, bendiocarb, and dieldrin and no obvious seasonal changes. In contrast, we detected high frequencies and striking seasonal changes for two kdr mutations associated with resistance to DDT and pyrethroids. In addition, the evaluation of the field populations from all seasons in terms of the combinations of polymorphisms at four resistance-associated mutations did not reveal the presence of insects that are resistant to all pesticides. Results from the morphological analysis displayed a similar pattern for both wings and did not show a clear separation among the samples from the

  3. The Dynamics of Halite Precipitation in the Dead Sea: Seasonal and Spatial Variations

    Science.gov (United States)

    Lensky, Nadav G.; Sirota, Ido; Arnon, Ali

    2016-04-01

    The Dead Sea is a deep hypersaline terminal lake that actively precipitates halite as a response to the negative water balance of the lake (evaporation > inflows). From mass balance consideration, a uniform ~3 m thick halite sequence is expected to cover the lake floor following the ~30 m level drop; however such a massive layer does not exist in the shallow water. In this talk we present new insights on the dynamics of halite precipitation and dissolution in a seasonally stratified lake, based on field observations. In situ monthly observations include the depth profile of the following: (i) halite precipitation rate, (ii) temperature, (iii) salinity, (iv) halite saturation, and (v) underwater photography of the sea floor and the water column - documentation of active halite precipitation/dissolution. We found a clear relation between the thermohaline stratification of the water column and halite precipitation/dissolution. The epilimnion experiences seasonal dissolution/precipitation cycle, while the hypolimnion continuously precipitates halite. We discuss the seasonal variations of the atmospheric forcing - the heat and water fluxes, and the response of the lake - thermohaline stratification and the precipitation/dissolution of halite along the water column and lake floor. We also discuss the role of diapycnal flux on the precipitation of halite and the salt fluxes. Geological implications on the lateral extent and thickness variations of evaporitic layers in evaporitic environments are also discussed.

  4. Diversity in plant hydraulic traits explains seasonal and inter-annual variations of vegetation dynamics in seasonally dry tropical forests.

    Science.gov (United States)

    Xu, Xiangtao; Medvigy, David; Powers, Jennifer S; Becknell, Justin M; Guan, Kaiyu

    2016-10-01

    We assessed whether diversity in plant hydraulic traits can explain the observed diversity in plant responses to water stress in seasonally dry tropical forests (SDTFs). The Ecosystem Demography model 2 (ED2) was updated with a trait-driven mechanistic plant hydraulic module, as well as novel drought-phenology and plant water stress schemes. Four plant functional types were parameterized on the basis of meta-analysis of plant hydraulic traits. Simulations from both the original and the updated ED2 were evaluated against 5 yr of field data from a Costa Rican SDTF site and remote-sensing data over Central America. The updated model generated realistic plant hydraulic dynamics, such as leaf water potential and stem sap flow. Compared with the original ED2, predictions from our novel trait-driven model matched better with observed growth, phenology and their variations among functional groups. Most notably, the original ED2 produced unrealistically small leaf area index (LAI) and underestimated cumulative leaf litter. Both of these biases were corrected by the updated model. The updated model was also better able to simulate spatial patterns of LAI dynamics in Central America. Plant hydraulic traits are intercorrelated in SDTFs. Mechanistic incorporation of plant hydraulic traits is necessary for the simulation of spatiotemporal patterns of vegetation dynamics in SDTFs in vegetation models.

  5. Dynamics of the seasonal variation of the North Equatorial Current bifurcation

    Science.gov (United States)

    Chen, Zhaohui; Wu, Lixin

    2011-02-01

    The dynamics of the seasonal variation of the North Equatorial Current (NEC) bifurcation is studied using a 1.5-layer nonlinear reduced-gravity Pacific basin model and a linear, first-mode baroclinic Rossby wave model. The model-simulated bifurcation latitude exhibits a distinct seasonal cycle with the southernmost latitude in June and the northernmost latitude in November, consistent with observational analysis. It is found that the seasonal migration of the NEC bifurcation latitude (NBL) not only is determined by wind locally in the tropics, as suggested in previous studies, but is also significantly intensified by the extratropical wind through coastal Kelvin waves. The model further demonstrates that the amplitude of the NEC bifurcation is also associated with stratification. A strong (weak) stratification leads to a fast (slow) phase speed of first-mode baroclinic Rossby waves, and thus large (small) annual range of the bifurcation latitude. Therefore, it is expected that in a warm climate the NBL should have a large range of annual migration.

  6. The Effect of Seasonal Weather Variation on the Dynamics of the Plague Disease

    Directory of Open Access Journals (Sweden)

    Rigobert C. Ngeleja

    2017-01-01

    Full Text Available Plague is a historic disease which is also known to be the most devastating disease that ever occurred in human history, caused by gram-negative bacteria known as Yersinia pestis. The disease is mostly affected by variations of weather conditions as it disturbs the normal behavior of main plague disease transmission agents, namely, human beings, rodents, fleas, and pathogens, in the environment. This in turn changes the way they interact with each other and ultimately leads to a periodic transmission of plague disease. In this paper, we formulate a periodic epidemic model system by incorporating seasonal transmission rate in order to study the effect of seasonal weather variation on the dynamics of plague disease. We compute the basic reproduction number of a proposed model. We then use numerical simulation to illustrate the effect of different weather dependent parameters on the basic reproduction number. We are able to deduce that infection rate, progression rates from primary forms of plague disease to more severe forms of plague disease, and the infectious flea abundance affect, to a large extent, the number of bubonic, septicemic, and pneumonic plague infective agents. We recommend that it is more reasonable to consider these factors that have been shown to have a significant effect on RT for effective control strategies.

  7. Soil radon dynamics in the Amer fault zone: An example of very high seasonal variations.

    Science.gov (United States)

    Moreno, V; Bach, J; Font, Ll; Baixeras, C; Zarroca, M; Linares, R; Roqué, C

    2016-01-01

    Soil radon levels of the Amer fault zone have been measured for a 4 year-period with the aim of checking seasonal fluctuations obtained in previous studies and to understand radon origin and dynamics. In this manuscript additional results are presented: updated continuous and integrated soil radon measurements, radionuclide content of soil materials and a detailed analysis of an urban profile by means of the electrical resistivity imaging technique and punctual soil radon, thoron and CO2 measurements. Integrated and continuous measurements present a wide range of values, [0.2-151.6] kBq m(-3) for radon, [4.5-39.6] kBq m(-3) for thoron and [4.0-71.2] g m(-2) day(-1) for CO2. The highest soil radon levels in the vicinity of the Amer fault (>40 kBq m(-3)) are found close to the fractured areas and present very important fluctuations repeated every year, with values in summer much higher than in winter, confirming previous studies. The highest radon values, up to 150 kBq m(-3), do not have a local origin because the mean value of radium concentration in this soil (19 ± 5 Bq kg(-1)) could not explain these values. Then soil radon migration through the fractures, influenced by atmospheric parameters, is assumed to account for such a high seasonal fluctuation. As main conclusion, in fractured areas, seasonal variations of soil radon concentration can be very important even in places where average soil radon concentration and radium content are not especially high. In these cases the migration capability of the soil is given not by intrinsic permeability but by the fracture structure. Potential risk estimation based on soil radon concentration and intrinsic permeability must be complemented with geological information in fractured systems.

  8. Seasonal variations of phytoplankton dynamics in Nunatsiavut fjords (Labrador, Canada) and their relationships with environmental conditions

    Science.gov (United States)

    Simo-Matchim, Armelle-Galine; Gosselin, Michel; Blais, Marjolaine; Gratton, Yves; Tremblay, Jean-Éric

    2016-04-01

    We assessed phytoplankton dynamics and its environmental control in four Labrador fjords (Nachvak, Saglek, Okak, and Anaktalak) during summer, early fall and late fall. Primary production and chlorophyll a (chl a) biomass were measured at seven optical depths, including the depth of subsurface chl a maximum (SCM). Phytoplankton abundance, size structure and taxonomy were determined at the SCM. Principal component analysis and non-metric multidimensional scaling were used to analyze relationships between production, biomass and community composition in relation to environmental variables. We observed a marked seasonal variability, with significant differences in phytoplankton structure and function between summer and fall. Surprisingly, primary production and chl a biomass were not significantly different from one fjord to another. The highest values of primary production (1730 mg C m- 2 day- 1) and chl a biomass (96 mg chl a m- 2) were measured during the summer bloom, and those high values indicate that Labrador fjords are highly productive ecosystems. The summer community showed relatively high abundance of nanophytoplankton (2-20 μm) while the fall community was characterized by low primary production and chl a biomass as well as relatively high abundance of picophytoplankton (< 2 μm). The low value of carbon potentially exported out of the euphotic zone throughout the study (≤ 31% of total primary production) suggests that phytoplankton production was mainly grazed by microzooplankton rather than being exported to greater depths. We observed a mixed assemblage of diatoms and flagellates in summer, whereas the fall community was largely dominated by flagellates. Seasonal variations in phytoplankton dynamics were mainly controlled by the strength of the vertical stratification and by the large differences in day length due to the northerly location of Labrador fjords. This study documents for the very first time phytoplankton structure and function in

  9. Dynamic response of deep-sea sediments to seasonal variations: a model

    OpenAIRE

    Soetaert, K.; Herman, P.M.J.; Middelburg, J. J.

    1996-01-01

    We present a dynamic, numerical model of early diagenetic processes that can be used to examine the response of different organic carbon mineralization pathways, concentration vs. depth profiles, and the resultant fluxes to seasonally varying carbon deposition. We show that there can be substantial temporal variability in sediment-water fluxes as well as in the relative contribution of different organic carbon mineralization pathways and oxygen consumption processes in deep-sea sediments. The...

  10. Seasonal variations in suspended-sediment dynamics in the tidal reach of an estuarine tributary

    Science.gov (United States)

    Downing-Kunz, Maureen A.; Schoellhamer, David H.

    2013-01-01

    Quantifying sediment supply from estuarine tributaries is an important component of developing a sediment budget, and common techniques for estimating supply are based on gages located above tidal influence. However, tidal interactions near tributary mouths can affect the magnitude and direction of sediment supply to the open waters of the estuary. We investigated suspended-sediment dynamics in the tidal reach of Corte Madera Creek, an estuarine tributary of San Francisco Bay, using moored acoustic and optical instruments. Flux of both water and suspended-sediment were calculated from observed water velocity and turbidity for two periods in each of wet and dry seasons during 2010. During wet periods, net suspended-sediment flux was seaward; tidally filtered flux was dominated by the advective component. In contrast, during dry periods, net flux was landward; tidally filtered flux was dominated by the dispersive component. The mechanisms generating this landward flux varied; during summer we attributed wind–wave resuspension in the estuary and subsequent transport on flood tides, whereas during autumn we attributed increased spring tide flood velocity magnitude leading to local resuspension. A quadrant analysis similar to that employed in turbulence studies was developed to summarize flux time series by quantifying the relative importance of sediment transport events. These events are categorized by the direction of velocity (flood vs. ebb) and the magnitude of concentration relative to tidally averaged conditions (relatively turbid vs. relatively clear). During wet periods, suspended-sediment flux was greatest in magnitude during relatively turbid ebbs, whereas during dry periods it was greatest in magnitude during relatively turbid floods. A conceptual model was developed to generalize seasonal differences in suspended-sediment dynamics; model application to this study demonstrated the importance of few, relatively large events on net suspended-sediment flux

  11. Investigation of dynamic behind the seasonal variations of Es and sporadic Na layer near the turbopause of aurora free zone

    Science.gov (United States)

    Yuan, T.; Sojka, J. J.; Criddle, N.; Cai, X.; Rice, D.

    2013-12-01

    The dearth of experimental observations, as well as dynamics study, near the turbopause (100-120 km) is the culprit for the mystery of this critical layer in the lower thermosphere. The sporadic E layer (Es) and the sporadic Na layer, occurring within this region, provide unique tracers for such topic. It is believed that the downward transporting of Es, which is full with metal ions (such as Na+), enriches the Na reservoir in the lower E region that causes the occurrence of sporadic Na layer within. In this paper, a statistic study show strong positive correlation between Es and sporadic Na layer above 100 km, measured by Utah State University Na lidar at Logan, Utah and CADI (ionosonde) at Bear Lake Observatory nearby. Both of these two turbopause features indicate strong seasonal variation with peak occurrence rate in the summer and minimum during the winter. To explain the dynamics behind the variations in the aurora free zone, HAMMONIA model produced monthly zonal wind climatology and Climatological Tidal Model of the Thermospehre (CTMT) are joining together to reproduce the hourly zonal wind variation within the turbopause, along with the temperature prediction from the two models. Using the well accepted wind shear theory of the Es formation, we conclude that such seasonal behaviors of Es and sporadic Na layer are due to large negative zonal wind shear driven by tidal wave peaking near the turbopause during summer time in the early evening.

  12. Atmospheric aerosols in Rome, Italy: sources, dynamics and spatial variations during two seasons

    Science.gov (United States)

    Struckmeier, Caroline; Drewnick, Frank; Fachinger, Friederike; Gobbi, Gian Paolo; Borrmann, Stephan

    2016-12-01

    every day at the urban location, at the suburban location they were only found under favourable meteorological conditions, but were independent of advection of the Rome emission plume. Particles from sources in the metropolitan area of Rome and particles advected from outside Rome contributed 42-70 and 30-58 % to the total measured PM1, respectively. Apart from the general aerosol characteristics, in this study the properties (e.g. emission strength) and dynamics (e.g. temporal behaviour) of each identified aerosol type is investigated in detail to provide a better understanding of the observed seasonal and spatial differences.

  13. Variation of upper layer dynamics during breakup of the seasonal ice cover in Hudson Bay

    Science.gov (United States)

    Lepage, Serge; Ingram, R. Grant

    1991-07-01

    The present study describes circulation and stratification changes associated with the melt and breakup of the seasonal ice cover in the coastal waters of southeast Hudson Day. Field work was carried out at a station located 25 km north of the Great Whale River. Buoyancy fluxes and dissipation rates were calculated as well as changes in potential energy. Surface velocity data were partitioned into frequency bands and complex demodulated. Throughout the sampling period, most of the current energy was found to be in the semi-diurnal tidal band. After ice breakup, however, low frequency and inertial motions became relatively more important in response to direct wind forcing at the sea surface. Changes in amplitudes and phases of the major tidal constituents occurred and are related to the presence of the sea ice cover. Between early April and mid-June, semi-diurnal current amplitude doubled while its phase shifted by 45 to 60 degrees. In early June, the ice cover was sufficiently dispersed to allow the surface turbulence to overcome the buoyancy flux and mix the upper water column.

  14. Multifluid MHD simulation of Saturn's magnetosphere: Dynamics of mass- and momentum-loading, and seasonal variation of the plasma sheet

    Science.gov (United States)

    Rajendar, A.; Paty, C. S.; Arridge, C. S.; Jackman, C. M.; Smith, H. T.

    2013-12-01

    Saturn's magnetosphere is driven externally, by the solar wind, and internally, by the planet's strong magnetic field, rapid rotation rate, and the addition of new plasma created from Saturn's neutral cloud. Externally, the alignment of the rotational and magnetic dipole axes, combined with Saturn's substantial inclination to its plane of orbit result in substantial curvature of the plasma sheet during solstice. Internally, new water group ions are produced in the inner regions of the magnetosphere from photoionization and electron-impact ionization of the water vapor and OH cloud sourced from Enceladus and other icy bodies in Saturn's planetary system. In addition to this, charge-exchange collisions between the relatively fast-moving water group ions and the slower neutrals results in a net loss of momentum from the plasma. In order to study these phenomena, we have made significant modifications to the Saturn multifluid model. This model has been previously used to investigate the external triggering of plasmoids and the interchange process using a fixed internal source rate. In order to improve the fidelity of the model, we have incorporated a physical source of mass- and momentum-loading by including an empirical representation of Saturn's neutral cloud and modifying the multifluid MHD equations to include mass- and momentum-loading terms. Collision cross-sections between ions, electrons, and neutrals are calculated as functions of closure velocity and energy at each grid point and time step, enabling us to simulate the spatially and temporally varying plasma-neutral interactions. In addition to this, by altering the angle of incidence of the solar wind relative to Saturn's rotational axis and applying a realistic latitudinally- and seasonally-varying ionospheric conductivity, we are also able to study seasonal effects on Saturn's magnetosphere. We use the updated multifluid simulation to investigate the dynamics of Saturn's magnetosphere, focusing specifically

  15. Seasonal variation in pediatric dermatoses

    Directory of Open Access Journals (Sweden)

    Banerjee Sabyasachi

    2010-01-01

    Full Text Available Introduction: The under-five population is a unique and vulnerable component of our society that always demands special attention. Aims: Our present work aimed to study the seasonal variation, age-wise variation and distribution of lesions of common dermatoses of this age group. Materials and Methods: We clinically studied all fresh cases attending the skin OPD of our hospital for one month each from summer, rainy season and winter. Total number of patients was 879. Results: The top six skin diseases in our study were impetigo, miliaria, scabies, furunculosis, seborrheic dermatitis and papular urticaria. On statistical analysis, scabies and seborrheic dermatitis were more prevalent during winter while impetigo, furunculosis and miliaria were more during summer and rainy season. Papular urticaria was more frequent in the rainy season. Seborrheic dermatitis predominantly affected the infants while impetigo, furunculosis, miliaria and popular urticaria were commoner in older age groups. Conclusion: Distribution of lesions of common dermatoses will help diagnose difficult cases and extensive evaluation of the body parts which, by virtue of being commonly affected, are must-examine sites in under-five children.

  16. Seasonal variation of mesopause region wind shears, convective and dynamic instabilities above Fort Collins, CO: A statistical study

    Science.gov (United States)

    Sherman, James P.; She, Chiao-Yao

    2006-06-01

    One thousand three hundred and eleven 15-min profiles of nocturnal mesopause region (80 105 km) temperature and horizontal wind, observed by Colorado State University sodium lidar over Fort Collins, CO (41°N, 105°W), between May 2002 and April 2003, were analyzed. From these profiles, taken over 390 h and each possessing vertical resolution of 2 km, a statistical analysis of seasonal variations in wind shears, convective and dynamical instabilities was performed. Large wind shears were most often observed near 100 km and during winter months. Thirty-five percent of the winter profiles contained wind shears exceeding 40 m/s per km at some altitude. In spite of large winds and shears, the mesopause region (at a resolution of 2 km and 15 min) is a very stable region. At a given altitude, the probability for convective instability is less than 1.4% for all seasons and the probability for dynamic instability (in the sense of Richardson number) ranges from 2.7% to 6.0%. Wind shear measurements are compared with four decades of chemical release measurements, compiled in a study by Larson [2002. Winds and shears in the mesosphere and lower thermosphere: results from four decades of chemical release wind measurements. Journal of Geophysical Research 107(A8), 1215]. Instability results are compared with those deduced from an annual lidar study conducted with higher spatial and temporal resolution at the Starfire Optical Range (SOR) in Albuquerque, NM, by Zhao et al. [2003. Measurements of atmospheric stability in the mesopause region at Starfire Optical Range, NM. Journal of Atmospheric and Solar-Terrestrial Physics 65, 219 232], and from a study by Li et al. [2005b. Characteristics of instabilities in the mesopause region over Maui, Hawaii. Journal of Geophysical Research 110, D09S12] with 19 days of data acquired from Maui Mesosphere and Lower Thermosphere (Maui MALT) Campaign . The Fort Collins lidar profiles were also analyzed using 1-h temporal resolution to compare

  17. Differences between dynamics factors for interannual and decadal variations of rainfall over the Yangtze River valley during flood seasons

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The rainfall over the Yangtze River valley during flood seasons (June to July) shows both interannual and decadal variations. The rainfall has been increasing since 1990, showing a decadal signal. The variations of rainfall are influenced by the multi-scale interactions in the atmosphere-ocean coupled climate system. The rainfall, SST, and circulation are analyzed with the Chinese 160 station data, and other observational/reanalysis data, respectively. The separation between the interannual and decadal variations is carried out. The key areas affecting the Yangtze rainfall are the western Pacific warm pool on the interannual time scale and the EINO3 area on the decadal time scale, respectively. The circulation anomaly associated with the interannual variation occurs in the upper troposphere whereas that associated with the decadal variation appears in the lower troposphere.

  18. [Diurnal and Seasonal Dynamic Variation of Soil Respiration and Its Influencing Factors of Different Fenced Enclosure Years in Desert Steppec].

    Science.gov (United States)

    Cui, Hai; Zhang, Ya-hong

    2016-04-15

    The fenced measures could improve the ecological environment of degraded grassland, it's a main measure for restoration of degraded grassland vegetation in China. Soil respiration (Rs) is an important component of an ecosystem's carbon cycle and the main pathway for carbon moving from the ecosystem to the atmosphere. In order to explore soil respiration characteristics and influencing factors of the different fenced years in arid desert grassland, we continuously observed Rs rate and environmental factors in the growing season of fenced enclosure 11a, 7a and no fenced (CK) desert steppe in Ningxia. The results showed that: (1) Both the diurnal andseasonal variations of Rs rate showed a single asymmetric peak changing in fenced enclosure of 11 years, 7 years, CK desert steppe. On the daily scale, the maximum and minimum values of Rs rate were found in the periods of 12:00-16:00 and 00:00-06:00,respectively. On the seasonal variation scale, the maximum value of Rs rate occurred in August with suitable precipitation and temperature conditions. And the Rs rate of the growing season of different fenced enclosure years was in the order of 11a [0.143 g · (m² · h)⁻¹] > 7a [0.138 g · (m² · h)⁻¹] > CK [0.106 g · (m2 - h)⁻¹]. (2) According to statistical analysis, it indicated that R² rate had a significant exponential positive relationship with air and soil temperature in fenced enclosure of 11 years, 7 years, CK desert steppe (P soil surface temperature (R²: 0.408-0.413) > air temperature (R2: 0.355-0.376) > 5-20 cm soil temperature (R2: 0.263-0.394). The temperature sensitivity coefficient Q, increased gradually with the soil depth, and Q1, of different fenced enclosure years was showed as 11 a (2.728) > 7a (2.436) > CK (2.086). (3) A significant quadratic function model (P soil moisture content of fenced enclosure 11a, 7a and CK desert steppe in the whole growing season. Rs rate had a significant linear negative correlation with air carbon dioxide

  19. Interannual and seasonal variation of chlorophyll-a off the Yellow River Mouth (1997-2012): Dominance of river inputs and coastal dynamics

    Science.gov (United States)

    Wu, Xiao; Duan, Haiqin; Bi, Naishuang; Yuan, Ping; Wang, Aimei; Wang, Houjie

    2016-12-01

    The temporal variations of sea surface chlorophyll-a concentration off the Yellow River Mouth were investigated using SeaWiFS and MODIS data over the period of 1997-2012. And the complex interplay of different dominant factors (e.g. river inputs and coastal dynamics) on the phytoplankton dynamics in different seasons was discussed. High concentration of nutrients from the Yellow River inputs plays a significant role in sustaining phytoplankton growth. Approximately 59% of the interannual variations of the chlorophyll-a concentration off the Yellow River Mouth were attributed to river inputs (water discharge, sediment load and median grain size of sediment particles). On seasonal time scale, the Yellow River discharge of water and nutrients is a major factor that influences the increased chlorophyll-a concentration from August to October (summer and autumn). From February to May, the stronger winds and enhanced wave actions resuspend and vertically mix the previously deposited riverine sediment and the associated nutrient, thus possibly contributing to higher chlorophyll-a concentration.

  20. SEASONAL VARIATIONS IN GROUNDWATER QUALITY OF ...

    African Journals Online (AJOL)

    2015-02-05

    Feb 5, 2015 ... Keys Words: Ground Water, Seasonal Variations, Valsad District, Gujarat. 1. ... that has to be conserved and preserved for sustenance of life in future [1]. .... evaporation of water and mixing of organic waste of animal origin [7].

  1. 489 SEASONAL VARIATION IN PHYSICO-CHEMICAL ...

    African Journals Online (AJOL)

    Osondu

    at different distances around the abattoir comprising Group A (within abattoir), Group B (60m from abattoir) and ... Keywords: Seasonal variation, Groundwater, Abattoir, Effluents, Water quality .... compared with the World Health Organisation.

  2. Seasonal variation of gravity waves in the Equatorial Middle Atmosphere: results from ISRO's Middle Atmospheric Dynamics (MIDAS program

    Directory of Open Access Journals (Sweden)

    G. Ramkumar

    2006-10-01

    Full Text Available Altitude profiles of temperature in the stratospheric and mesopheric region from lidar observations at NARL, Gadanki, India, during December 2002–April 2005, as part of ISRO's Middle Atmospheric Dynamics – "MIDAS (2002–2005" program are used to study the characteristics of gravity waves and their seasonal variation. Month-to-month variation of the gravity wave activity observed during the period of December 2002–April 2005 show maximum wave activity, with primary peaks in May 2003, August 2004 and March 2005 and secondary peaks in February 2003 and November 2004. This month-to-month variation in gravity wave activity is linked to the variation in the strength of the sources, viz. convection and wind shear, down below at the tropospheric region, estimated from MST radar measurements at the same location. Horizontal wind shear is found to be mostly correlated with wave activity than convection, and sometimes both sources are found to contribute towards the wave activity.

  3. Seasonal variations in menarche in Oslo.

    Science.gov (United States)

    Brundtland, G H; Liestøl, K

    1982-01-01

    Data from about 11,000 girls aged 10-18 years were used to study seasonal variations in menarche in Oslo, Norway. A statistical method which takes into account the changes over time in the age-structure of the sample is used to show that throughout the period 1965-1970, the menarche incidence varied according to a stable bimodal seasonal pattern with peaks in December-January and July-August. This pattern corresponds to those observed in Sweden and Finland, but deviates from other reported patterns, i.e. from the variations found in Copenhagen. It is argued that a possible cause of general lack of well supported hypotheses for seasonal variations is that an environmental factor may cause marked cyclic variations, without having a marked effect on the process determining maturation.

  4. Seasonal and ontogenetic variation of skin microbial communities and relationships to natural disease dynamics in declining amphibians

    Science.gov (United States)

    Longo, Ana V.; Savage, Anna E.; Hewson, Ian; Zamudio, Kelly R.

    2015-01-01

    Recently, microbiologists have focused on characterizing the probiotic role of skin bacteria for amphibians threatened by the fungal disease chytridiomycosis. However, the specific characteristics of microbial diversity required to maintain health or trigger disease are still not well understood in natural populations. We hypothesized that seasonal and developmental transitions affecting susceptibility to chytridiomycosis could also alter the stability of microbial assemblages. To test our hypothesis, we examined patterns of skin bacterial diversity in two species of declining amphibians (Lithobates yavapaiensis and Eleutherodactylus coqui) affected by the pathogenic fungus Batrachochytrium dendrobatidis (Bd). We focused on two important transitions that affect Bd susceptibility: ontogenetic (from juvenile to adult) shifts in E. coqui and seasonal (from summer to winter) shifts in L. yavapaiensis. We used a combination of community-fingerprinting analyses and 16S rRNA amplicon sequencing to quantify changes in bacterial diversity and assemblage composition between seasons and developmental stages, and to investigate the relationship between bacterial diversity and pathogen load. We found that winter-sampled frogs and juveniles, two states associated with increased Bd susceptibility, exhibited higher diversity compared with summer-sampled frogs and adult individuals. Our findings also revealed that hosts harbouring higher bacterial diversity carried lower Bd infections, providing support for the protective role of bacterial communities. Ongoing work to understand skin microbiome resilience after pathogen disturbance has the potential to identify key taxa involved in disease resistance. PMID:26587253

  5. Seasonal variation in food allergy to apple

    DEFF Research Database (Denmark)

    Skamstrup Hansen, K; Vieths, S; Vestergaard, H

    2001-01-01

    The aim of the study was to investigate the possibility of a seasonal variation in reactivity to apples in 27 birch pollen allergic patients. Before and during the birch pollen season 1998, the patients were subjected to double-blind, placebo-controlled food challenges (DBPCFCs) with grated fresh...... Golden Delicious apple followed by an open food challenge with whole fresh apple. The clinical reactions elicited during the challenges were evaluated both by the patients and the investigators. Moreover, the skin reactivity and the in vitro reactivity to apple were evaluated by skin prick test (SPT...

  6. Seasonal Variation of Cistus ladanifer L. Diterpenes

    Science.gov (United States)

    Alías, Juan Carlos; Sosa, Teresa; Valares, Cristina; Escudero, José Carlos; Chaves, Natividad

    2012-01-01

    The exudate of Cistus ladanifer L. consists mainly of two families of secondary metabolites: flavonoids and diterpenes. The amount of flavonoids present in the leaves has a marked seasonal variation, being maximum in summer and minimum in winter. In the present study, we demonstrate that the amount of diterpenes varies seasonally, but with a different pattern: maximum concentration in winter and minimum in spring-summer. The experiments under controlled conditions have shown that temperature influences diterpene production, and in particular, low temperatures. Given this pattern, the functions that these compounds perform in C. ladanifer are probably different. PMID:27137636

  7. Seasonal Variation of Cistus ladanifer L. Diterpenes

    Directory of Open Access Journals (Sweden)

    Juan Carlos Alías

    2012-07-01

    Full Text Available The exudate of Cistus ladanifer L. consists mainly of two families of secondary metabolites: flavonoids and diterpenes. The amount of flavonoids present in the leaves has a marked seasonal variation, being maximum in summer and minimum in winter. In the present study, we demonstrate that the amount of diterpenes varies seasonally, but with a different pattern: maximum concentration in winter and minimum in spring-summer. The experiments under controlled conditions have shown that temperature influences diterpene production, and in particular, low temperatures. Given this pattern, the functions that these compounds perform in C. ladanifer are probably different.

  8. Surface ultraviolet radiation over east Siberia: seasonal variations

    Directory of Open Access Journals (Sweden)

    A. V. Mikhalev

    Full Text Available The results of spectral measurements of the daily near-noon surface direct solar ultraviolet radiation in the wavelength range of 295–345 nm obtained in Irkutsk (East Siberia for the time interval of 1998–2000 are presented. For the period under consideration, the seasonal UV radiation variations are analysed that are associated with the total ozone dynamics, the transition of cyclonic and anticyclonic (Siberian anticyclone periods, the presence of snow cover, and other factors. The analysis reveals an asymmetric behaviour of the seasonal course in ground-level UV radiation around the time of the summer solstice, with seasonal variation dependence on the wavelength. We have determined the irregular variations of surface UV radiation that is typical for the region, with their properties dependent on the season and on the spectral range analysed. The similarity of the above noted features from year to year was revealed.

    Key words. Atmospheric composition and structure (Transmission and scattering of radiation; instruments and techniques – Meteorology and atmospheric dynamics (middle atmosphere dynamics

  9. Seasonal variation of heat consumption in greenhouses

    DEFF Research Database (Denmark)

    Nielsen, O.F.; Amsen, M.G.; Strøm, J.S.

    The concept of dynamic variation is introduced as a method to visualize the dynamic fluctuations of heat consumption and thermal climate in greenhouses. The feasibility of the concept is illustrated by describing effects of different greenhouse designs. Engineering data on design heat consumption...

  10. Occurrence of suicide and seasonal variation

    Directory of Open Access Journals (Sweden)

    Retamal C. Pedro

    1998-01-01

    Full Text Available OBJECTIVE: To review the estimated suicide rates for the Region Metropolitan, the main socio-political center in Chile, for the period 1979-1994, and to determine whether they follow a seasonal pattern. METHOD: Data available for the period 1979-94 at the Forensic Services in Chile was analyzed using ANOVA. RESULTS: It was register 5.386 suicides. While the "warm" months (October, November, December & January concentrated 39.0% of cases, the so called "cold" months reported 28,7%. This contrast is made even clearer by the month-to-month analysis, showing the highest suicide rate in December (10.9% against the lowest rate in June (7.0%. Further statistical analysis revealed these differences to be significant. CONCLUSION: The study shows that in Chile, representing as it does the Southern Hemisphere, the suicide rates tend to present a seasonal variation as has elsewhere been determined for in the North Hemisphere.

  11. Contagious yawning and seasonal climate variation

    Directory of Open Access Journals (Sweden)

    Andrew C Gallup

    2011-09-01

    Full Text Available Recent evidence suggests that yawning is a thermoregulatory behavior. To explore this possibility further, the frequency of contagious yawning in humans was measured while outdoors in a desert climate in the United States during two distinct temperature ranges and seasons (winter: 22oC; early summer: 37oC. As predicted, the proportion of pedestrians who yawned in response to seeing pictures of people yawning differed significantly between the two conditions (winter: 45%; summer: 24%. Across conditions yawning occurred at lower ambient temperatures, and the tendency to yawn during each season was associated with the length of time spent outside prior to being tested. Participants were more likely to yawn in the milder climate after spending long periods of time outside, while prolonged exposure to ambient temperatures at or above body temperature was associated with reduced yawning. This is the first report to show that the incidence of yawning in humans is associated with seasonal climate variation, further demonstrating that yawn-induced contagion effects can be mediated by factors unrelated to individual social characteristics or cognitive development.

  12. Phytoplankton Biomass Dynamics in the Strait of Malacca within the Period of the SeaWiFS Full Mission: Seasonal Cycles, Interannual Variations and Decadal-Scale Trends

    Directory of Open Access Journals (Sweden)

    Eko Siswanto

    2014-03-01

    Full Text Available Seasonal cycles, interannual variations and decadal trends of Sea-viewing Wide Field-of-view Sensor (SeaWiFS-retrieved chlorophyll-a concentration (Chl-a in the Strait of Malacca (SM were investigated with reconstructed, cloud-free SeaWiFS Chl-a during the period of the SeaWiFS full mission (September 1997 to December 2010. Pixel-based non-parametric correlations of SeaWiFS Chl-a on environmental variables were used to identify the probable causes of the observed spatio-temporal variations of SeaWiFS Chl-a in northern, middle and southern regions of the SM. Chl-a was high (low during the northeast (southwest monsoon. The principal causes of the seasonality were wind-driven vertical mixing in the northern region and wind-driven coastal upwelling and possibly river discharges in the middle region. Among the three regions, the southern region showed the largest interannual variations of Chl-a. These variations were associated with the El Niño/Southern Oscillation (ENSO and river runoff. Interannual variations of Chl-a in the middle and northern regions were more responsive to the Indian Ocean Dipole and ENSO, respectively, with atmospheric deposition being the most important driver. The most significant decadal-scale trend of increasing Chl-a was in the southern region; the trend was moderate in the middle region. This increasing trend was probably caused by environmental changes unrelated to the variables investigated in this study.

  13. Short-term dynamics and partitioning of newly assimilated carbon in the foliage of adult beech and pine are driven by seasonal variations

    Science.gov (United States)

    Desalme, Dorine; Priault, Pierrick; Gérant, Dominique; Dannoura, Masako; Maillard, Pascale; Plain, Caroline; Epron, Daniel

    2017-04-01

    Carbon (C) allocation is a key process determining C cycling in forest ecosystems. However, the mechanisms underlying the annual patterns of C partitioning in trees, influenced by tree phenology and environmental conditions, are not well identified yet. This study aimed to characterize the short-term dynamics and partitioning of newly assimilated carbon in the foliage of adult European beeches (Fagus sylvatica) and maritime pines (Pinus pinaster) across the seasons. We hypothesized that residence times of recently assimilated C in C compounds should change according to the seasons and that seasonal pattern should differ between deciduous and evergreen tree species, since they have different phenology. 13CO2 pulse-labelling experiments were performed in situ at different dates corresponding to different phenological stages. In beech leaves and pine needles, C contents, isotopic compositions, and 13C dynamics parameters were determined in total organic matter (bulk foliage), in polar fraction (PF, including soluble sugars, amino acids, organic acids) and in starch. For both species and at each phenological stage, 13C amount in bulk foliage decreased following a two-pool exponential model, highlighting the partitioning of newly assimilated C between 'mobile' and 'stable' pools. The relative proportion of the stable pool was maximal in beech leaves in May, when leaves were still growing and could incorporate newly assimilated C in structural C compounds. Young pine needles were still receiving C from previous-year needles in June (two months after budburst) although they are already photosynthesizing, acting as a strong C sink. In summer, short mean residence times of 13C (MRT) in foliage of both tree species reflected the fast respiration and exportation of recent photosynthates to support the whole tree C demand (e.g., supplying perennial organ growth). At the end of the growing season, pre-senescing beech leaves were supplying 13C to perennial organs, whereas

  14. Factors controlling seasonal variations in Arctic black carbon

    Science.gov (United States)

    Shen, Z.; Ming, Y.; Horowitz, L. W.

    2015-12-01

    Arctic haze has a distinct seasonality with higher concentrations in winter and spring. This study evaluates how different processes of large-scale circulation and removal control seasonal variations in Arctic black carbon (BC) using the Geophysical Fluid Dynamics Laboratory (GFDL) atmospheric general circulation model (AM3). We find that transport and wet deposition play unequal roles in determining Arctic BC seasonal cycle. Despite seasonal differences in general circulation patterns, the eddy-driven BC transport changes little throughout the year, and the seasonal cycle of Arctic BC is attributed to wet removal. BC hydrophilic fraction affected by the aging process and hydrophilic BC (BCpi) wet deposition rate affected by cloud microphysics determine wet deposition. Both low hydrophilic fraction and low wet deposition rate account for the peak of BC in winter. The transition to low BC in summer results from an increase in wet deposition rate, while the return of BC in late autumn is mainly caused by a sharp decrease in hydrophilic fraction. The results suggest that the concentrations of Arctic aerosols as well as their climate impacts may be susceptible to modification in a future climate.

  15. Seasonal and interannual variations in snow cover thickness, glacier mass balance, and gravity-induced dynamics in a high Arctic valley glacier watershed.

    Science.gov (United States)

    Prokop, Alexander; Tolle, Florian; Bernard, Eric; Friedt, Jean-Michel; Griselin, Madeleine

    2015-04-01

    For 3 consecutive years, terrestrial laser scanning surveys have been conducted in the glacier basin of Austre Lovénbreen (Svalbard, 79°N). Each year, high density point clouds were acquired on the glacier surface and on the surrounding slopes. Two yearly scanning sessions were required in order to spatialize and quantify snow cover. The first session was done late April at the expected annual snow maximum. The second session was done in August near the end of the melting season. On the glacier itself, laser scans were produced on the glacier snout, in the area close to the equilibrium line, and in the upper reaches of the glacier. Manual snow drilling measurements and glacier mass balance data were subsequently used to validate snow cover results. In the steep slopes surrounding the glacier, scans were acquired on slopes at various altitudes and orientations in order to get a representative view of different snow cover settings. Particular attention was granted to snowdrift and avalanche processes, and their consequences on remaining packed snow stored in perennial snow accumulation at the bottom of slopes. A good knowledge of the dynamics of the snow cover is of particular interest in a glacier undergoing a clear retreat. Snow is protecting the ice from melting for part of the season, and snow is also providing what will constitute future glacier ice in the upper reaches of the basin. Snow on slopes is also of importance as avalanches reaching on the glacier can contribute to the overall mass balance. Snow cover, by keeping the slopes permafrost from thawing early in the season, or by providing liquid water affecting it later in the season, is also playing a key role in the glacier basin morphology and its interactions with the glacier body.

  16. Seasonal and interannual variations in snow cover thickness, water equivalent, and gravity-induced dynamics in a high Arctic valley glacier watershed.

    Science.gov (United States)

    Tolle, F.; Prokop, A.; Bernard, É.; Friedt, J. M.; Griselin, M.

    2014-12-01

    For 3 consecutive years, terrestrial laser scanning surveys have been conducted in the glacier basin of Austre Lovénbreen (Svalbard, 79°N). Each year, high density point clouds were acquired on the glacier surface and on the surrounding slopes. Two yearly scanning sessions were required in order to spatialize and quantify snow cover. The first session was done late April at the expected annual snow maximum. The second session was done in August near the end of the melting season and before the first potential significant snow falls. On the glacier itself, laser scans were produced on the glacier snout, in the area close to the equilibrium line, and in the upper reaches of the glacier. Manual snow drilling measurements and glacier mass balance data were subsequently used to validate snow cover results. In the steep slopes surrounding the glacier, scans were acquired on slopes at various altitudes and orientations in order to get a representative view of different snow cover settings. Particular attention was granted to snowdrift and avalanche processes, and their consequences on remaining packed snow stored in perennial snow accumulation at the bottom of slopes. A good knowledge of the dynamics of the snow cover is of particular interest in a glacier undergoing a clear retreat. Snow is slowing the melting of the ice for part of the season, and snow is also providing what will constitute future glacier ice in the upper reaches of the basin. Snow on slopes is also of importance as avalanches reaching on the glacier can contribute to the overall mass balance. Snow cover, by keeping the slopes permafrost from thawing early in the season, or by providing liquid water affecting it later in the season, is also playing a key role in the glacier basin morphology and its interactions with the glacier body.

  17. Seasonal module dynamics in Sargassum subrepandum (Fucales, Phaeophyta)

    NARCIS (Netherlands)

    Ateweberhan, Mebrahtu; Bruggemann, J. Henrich; Breeman, Anneke M.

    2008-01-01

    Module dynamics of the fucoid alga Sargassum subrepandum (Forssk.) C. Agardh was studied in the southern Red Sea. Seasonal variation in thallus density and size was determined, and the initiation, growth, reproduction, and shedding of modules (primary laterals) were ascertained, using a tagging appr

  18. Seasonal module dynamics in Sargassum subrepandum (Fucales, Phaeophyta)

    NARCIS (Netherlands)

    Ateweberhan, Mebrahtu; Bruggemann, J. Henrich; Breeman, Anneke M.

    Module dynamics of the fucoid alga Sargassum subrepandum (Forssk.) C. Agardh was studied in the southern Red Sea. Seasonal variation in thallus density and size was determined, and the initiation, growth, reproduction, and shedding of modules (primary laterals) were ascertained, using a tagging

  19. Seasonal Variation of Major Elements in South Lake Cyohoha, Rwanda

    Institute of Scientific and Technical Information of China (English)

    Jean de Dieu Bazimenyera; Fu Qiang; Thophila Niragire

    2014-01-01

    The paper analyzed the seasonal variation of the concentrations of Cr, Mn, Al, N, P, As, Ba, Ca, Cu, Fe, Mg, and K in South Lake Cyohoha water using spectroscopic technique. Water samples were taken monthly at Ngenda, Karehe and Nyamabuye stations from January 2009 to December 2010. The results showed that the concentrations of aluminum, nitrogen, potassium, arsenic, phosphorous, manganese, chromium, barium and copper were high during the raining season and low during the dry season, while calcium, iron and magnesium varied independently with seasonal change. The results of conductivity and pH also confirmed the effects of seasonal change on the quality of water in the South Lake Cyohoha since the highest value of conductivity was found during the raining season, while the smallest was observed during the dry season, for pH the highest number was noticed during the dry season and the lowest during the raining season.

  20. Seasonal variations in hospital admissions for mania

    DEFF Research Database (Denmark)

    Medici, Clara Reece; Vestergaard, Claus Høstrup; Hadzi-Pavlovic, Dusan;

    2016-01-01

    Central Research Register. The Danish Meteorological Institute provided the meteorological variables. The association between weather and admissions was tested using linear regression. RESULTS: Our database comprised 24,313 admissions with mania. There was a seasonal pattern with admission rates peaking...

  1. Seasonal variations in the microflora from mangrove swamps in Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Matondkar, S.G.P.; Mathani, S.; Mavinkurve, S.

    Seasonal variations in bacterial and fungal counts from the water and sediment samples of mangrove ecosystem of Goa (India) show that this ecosystem supports a very high population of fungi and bacteria...

  2. Seasonal Variations of Cell Site Diversity Gain

    Directory of Open Access Journals (Sweden)

    Sharmini Enoch

    2016-08-01

    Full Text Available The broadband fixed wireless access (BFWA systems operate in microwave frequencies. In this frequency range, the wave propagation is highly influenced by precipitation caused especially by rain. With the use of cell site diversity (CSD, the rain attenuation effects can be mitigated. When the signal level falls below a certain threshold the subscriber station switches to another base station within the coverage area. This paper aims at demonstrating the performance improvements obtained with the use of cell site diversity during various seasons for measurements carried out from HYREX rain gauge network in UK. The parameters traditionally used to quantify cell site diversity are CSD gain and diversity improvement. This paper analyzes the CSD gain achieved. The gain increases with increasing frequency and distance. The link performance is compared for various seasons and the results show that the maximum attenuation occurs during summer, while the least attenuation occurs during winter. Therefore, maximum gain of up to 22 dB occurs at 54 GHz frequency during winter. The second observation is that when the angular separation between the diversity sites is 180° separation there is maximum gain for all seasons.

  3. Analysis of seasonal variation of water masses in East China Sea

    Science.gov (United States)

    Qi, Jifeng; Yin, Baoshu; Zhang, Qilong; Yang, Dezhou; Xu, Zhenhua

    2014-07-01

    Seasonal variations of water masses in the East China Sea (ECS) and adjacent areas are investigated, based on historical data of temperature and salinity ( T-S). Dynamic and thermodynamic mechanisms that affect seasonal variations of some dominant water masses are discussed, with reference to meteorological data. In the ECS above depth 600 m, there are eight water masses in summer but only five in winter. Among these, Kuroshio Surface Water (KSW), Kuroshio Intermediate Water (KIW), ECS Surface Water (ECSSW), Continental Coastal Water (CCW), and Yellow Sea Surface Water (YSSW) exist throughout the year. Kuroshio Subsurface Water (KSSW), ECS Deep Water (ECSDW), and Yellow Sea Bottom Water (YSBW) are all seasonal water masses, occurring from May through October. The CCW, ECSSW and KSW all have significant seasonal variations, both in their horizontal and vertical extents and their T-S properties. Wind stress, the Kuroshio and its branch currents, and coastal currents are dynamic factors for seasonal variation in spatial extent of the CCW, KSW, and ECSSW, whereas sea surface heat and freshwater fluxes are thermodynamic factors for seasonal variations of T-S properties and thickness of these water masses. In addition, the CCW is affected by river runoff and ECSSW by the CCW and KSW.

  4. [Diurnal and seasonal variations of energy balance over Horqin meadow].

    Science.gov (United States)

    Li, Hui-dong; Guan, De-Xin; Yuan, Feng-Hui; Ren, Yan; Wang, An-Zhi; Jin, Chang-Jie; Wu, Jia-Bing

    2014-01-01

    Based on the measurements of eddy flux and micrometeorological factors, this paper analyzed the diurnal and seasonal variations of energy balance over Horqin meadow. The results showed that annual energy balance ratio (EBR) of the eddy covariance system was 0.77, and EBR was biggest in growing season, middle in bare soil period and smallest in snow-covered period. Diurnal variations of energy components all presented bell-shaped curves. The peak of net radiation appeared around 12:00 and peaks of other components slightly lagged. Seasonal variation of net radiation presented a single-peak curve, and the annual average was 5.71 MJ x m(-2) x d(-1). Seasonal variation of latent heat flux was similar to that of net radiation, and the annual average was 2.84 MJ x m(-2) x d(-1). Seasonal variation of sensible heat flux presented a double-peak curve, and the peaks appeared in April and September, respectively. Annual averaged sensible heat flux was 1.87 MJ x m(-2) x d(-1). Maximum soil heat flux (3.47 MJ x m(-2) x d(-1)) appeared in April, and the soil heat flux became negative after September. Annual budget ratios of energy components presented a decreasing order of latent heat flux, sensible heat flux and soil heat flux, which accounted for 49.8%, 35.8% and 3.1% of net radiation, respectively. Seasonal variation of Bowen ratio (beta) presented a 'U' shape, and the annual average was 1.61. beta was small (0.18) and relatively stable in growing season, while it was large (2.39) and fluctuated severely in non-growing season.

  5. Seasonal variation of dystocia in a large Danish cohort.

    Directory of Open Access Journals (Sweden)

    Christine Rohr Thomsen

    Full Text Available BACKGROUND: Dystocia is one of the most frequent causes of cesarean delivery in nulliparous women. Despite this, its causes are largely unknown. Vitamin D receptor (VDR has been found in the myometrium. Thus, it is possible that vitamin D affects the contractility of the myometrium and may be involved in the pathogenesis of dystocia. Seasonal variation of dystocia in areas with distinct seasonal variation in sunlight exposure, like Denmark, could imply that vitamin D may play a role. This study examined whether there was seasonal variation in the incidence of dystocia in a Danish population. METHOD: We used information from a cohort of 34,261 nulliparous women with singleton pregnancies, spontaneous onset of labor between 37 and 42 completed gestational weeks, and vertex fetal presentation. All women gave birth between 1992 and 2010 at the Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby. Logistic regression combined with cubic spline was used to estimate the seasonal variation for each outcome after adjusting for calendar time. RESULTS: No evidence for seasonal variation was found for any of the outcomes: acute cesarean delivery due to dystocia (p = 0.44; instrumental vaginal delivery due to dystocia (p = 0.69; oxytocin augmentation due to dystocia (p = 0.46; and overall dystocia (p = 0.91. CONCLUSION: No seasonal variation in the incidence of dystocia was observed in a large cohort of Danish women. This may reflect no association between vitamin D and dystocia, or alternatively that other factors with seasonal variation and influence on the occurrence of dystocia attenuate such an association.

  6. Seasonal dynamics of plankton communities coupled with ...

    African Journals Online (AJOL)

    Seasonal dynamics of plankton communities coupled with environmental factors ... In this study, we studied the influence of the physical-chemical and biological ... which are well related to changes in algae diversity and abundance, noting that ... The “top-down” effect of planktivorous fish on the zooplankton is a significant ...

  7. Seasonal Variation in Human Salivary Cortisol Concentration

    DEFF Research Database (Denmark)

    Persson, Roger; Garde, Anne Helene; Hansen, Åse Marie

    2008-01-01

    Measurement of cortisol concentration can contribute important information about an individual's ability to adjust to various environmental demands of both physical and psychosocial origin. However, one uncertainty that affects the possibilities of correctly interpreting and designing field studies...... is the lack of observations of the impact of seasonal changes on cortisol excretion. For this reason, the month-to-month changes in diurnal cortisol concentration, the awakening cortisol response (ACR), maximum morning concentration, and fall during the day were studied in a group of 24 healthy men and women...... 32 to 61 yrs of age engaged in active work. On one workday for 12 consecutive months, participants collected saliva at four time points for determination of cortisol: at awakening, +30 min, +8 h, and at 21:00 h. Data were analyzed by a repeated measures design with month (12 levels) and time...

  8. Does seasonal variation influence the phytochemical and ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-11-19

    Nov 19, 2008 ... (Model 32BL79, Dynamics Corporation, New Hartfort, CT, U.S.A) and filtered through ... Due to the vast differences in the nature of the chemical constituents ... the compound was not well soluble in these two solvent systems.

  9. Light-driven growth in Amazon evergreen forests explained by seasonal variations of vertical canopy structure.

    Science.gov (United States)

    Tang, Hao; Dubayah, Ralph

    2017-03-07

    Light-regime variability is an important limiting factor constraining tree growth in tropical forests. However, there is considerable debate about whether radiation-induced green-up during the dry season is real, or an apparent artifact of the remote-sensing techniques used to infer seasonal changes in canopy leaf area. Direct and widespread observations of vertical canopy structures that drive radiation regimes have been largely absent. Here we analyze seasonal dynamic patterns between the canopy and understory layers in Amazon evergreen forests using observations of vertical canopy structure from a spaceborne lidar. We discovered that net leaf flushing of the canopy layer mainly occurs in early dry season, and is followed by net abscission in late dry season that coincides with increasing leaf area of the understory layer. Our observations of understory development from lidar either weakly respond to or are not correlated to seasonal variations in precipitation or insolation, but are strongly related to the seasonal structural dynamics of the canopy layer. We hypothesize that understory growth is driven by increased light gaps caused by seasonal variations of the canopy. This light-regime variability that exists in both spatial and temporal domains can better reveal the drought-induced green-up phenomenon, which appears less obvious when treating the Amazon forests as a whole.

  10. Seasonal variation of household food waste in Denmark

    DEFF Research Database (Denmark)

    Edjabou, Vincent Maklawe Essonanawe; Petersen, Claus; Scheutz, Charlotte

    This paper analysed the influence of seasonal variation in the generation of the Danish household food waste. Residual household waste was sampled and manually sorted into six food waste fractions. Vegetable food wastes were the main fraction contributing to the household food waste. Statistical...... analysis showed a significant relationship between avoidable food waste and household size. However, there were no significant seasonal differences in the amount of avoidable food waste....

  11. Seasonal variation of flavonoids in Teucrium polium L. (Lamiaceae

    Directory of Open Access Journals (Sweden)

    Gjoshe Stefkov

    2009-02-01

    Full Text Available Тhe aim of the present study was identification of flavone aglycones and determination of the content of each and the content of total flavonoids as well as investigation of the eventual seasonal variations of flavonoids in Teucrium polium L. (Lamiaceae. The plant samples were collected at six different locations in Republic of Macedonia, during summer in 1999, 2000 and 2003. For determination of seasonal variations, the samples were collected in v. Koleshino, in 2004, each month during the whole season. Six flavone aglycones (luteolin, apigenin, diosmetin, cirsiliol, cirsimaritin and cirsilineol were identified in the hydrolyzed extracts of the over ground part of Teucrium polium by HPLC method. The most abundant flavone was luteolin, followed by apigenin and cirsimaritin. Great seasonal variations were found in the content of each and in the content of total amount of flavonoids. The most abundant flavone during the whole season was luteolin with the highest content in May. The content of total flavonids was the highest in the period from May to July, which could be recommended as the most convenience period in the season for collecting of the plant material from Teucrium polium.

  12. A dynamic model of some malaria-transmitting anopheline mosquitoes of the Afrotropical region. II. Validation of species distribution and seasonal variations.

    Science.gov (United States)

    Lunde, Torleif M; Balkew, Meshesha; Korecha, Diriba; Gebre-Michael, Teshome; Massebo, Fekadu; Sorteberg, Asgeir; Lindtjørn, Bernt

    2013-02-25

    The first part of this study aimed to develop a model for Anopheles gambiae s.l. with separate parametrization schemes for Anopheles gambiae s.s. and Anopheles arabiensis. The characterizations were constructed based on literature from the past decades. This part of the study is focusing on the model's ability to separate the mean state of the two species of the An. gambiae complex in Africa. The model is also evaluated with respect to capturing the temporal variability of An. arabiensis in Ethiopia. Before conclusions and guidance based on models can be made, models need to be validated. The model used in this paper is described in part one (Malaria Journal 2013, 12:28). For the validation of the model, a data base of 5,935 points on the presence of An. gambiae s.s. and An. arabiensis was constructed. An additional 992 points were collected on the presence An. gambiae s.l.. These data were used to assess if the model could recreate the spatial distribution of the two species. The dataset is made available in the public domain. This is followed by a case study from Madagascar where the model's ability to recreate the relative fraction of each species is investigated. In the last section the model's ability to reproduce the temporal variability of An. arabiensis in Ethiopia is tested. The model was compared with data from four papers, and one field survey covering two years. Overall, the model has a realistic representation of seasonal and year to year variability in mosquito densities in Ethiopia. The model is also able to describe the distribution of An. gambiae s.s. and An. arabiensis in sub-Saharan Africa. This implies this model can be used for seasonal and long term predictions of changes in the burden of malaria. Before models can be used to improving human health, or guide which interventions are to be applied where, there is a need to understand the system of interest. Validation is an important part of this process. It is also found that one of the main

  13. Seasonal variation of the barrier layer in the PN section

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yuan; WU Dexing; LIN Xiaopei; SHAN Feng

    2009-01-01

    In this paper, we use the conductivity-temperature-depth (CTD) observation data and a three-dimensional ocean model in a seasonally-varying forcing field to study the barrier layer (BL) in the PN section in the East China Sea (ECS). The BL can be found along the PN section with obviously seasonal variability. In winter, spring and autumn, the BL occurs around the slope where the cold shelf water meets with the warm Kuroshio water. In summer, the BL can also be found in the shelf area near salinity front of the Changjiang (Yangtze) River Dilution Water (YRDW). Seasonal variations of BL in the PN section are caused by local hydrological characteristics and seasonal variations of atmospheric forcing. Strong vertical convection caused by sea surface cooling thickens the BL in winter and spring in the slope area. Due to the large discharge of Changjiang River in summer, the BL occurs extensively in the shelf region where the fresh YRDW and the salty bottom water meet and form a strong halocline above the seasonal thermocline. The formation mechanism of BL in the PN section can be explained by the vertical shear of different water masses, which is called the advection mechanism. The interannual variation of BL in summer is greatly affected by the YRDW. In the larger YRDW year (such as 1998), a shallow but much thicker BL existed on the shelf area.

  14. Seasonal variation of the protozooplanktonic community in a tropical oligotrophic environment (Ilha Solteira reservoir, Brazil

    Directory of Open Access Journals (Sweden)

    AS Mansano

    Full Text Available The seasonal variation of the protozooplanktonic community (ciliates and testate amoebae was studied in a tropical oligotrophic reservoir in Brazil, which was under the influence of two contrasting climatic seasons (rainy/warm and dry/cold. The aim of this study was to evaluate the effect of these climatic changes on physical, chemical and biological variables in the dynamic of this community. The highest mean density of total protozoans occurred in the rainy/warm season (5683.2 ind L−1, while the lowest was in the dry/cold (2016.0 ind L−1. Considering the seasonal variations, the protozoan groups that are truly planktonic, such as the oligotrichs (Spirotrichea, predominated in the dry season, whereas during the rainy season, due to the material input and resuspension of sediment, sessile protozoans of the Peritrichia group were the most important ones. The dominant protozoans were Urotricha globosa, Cothurnia annulata, Pseudodifflugia sp. and Halteria grandinella. The highest densities of H. grandinella were associated with more oxygenated and transparent water conditions, while the highest densities of C. annulata occurred in sites with high turbidity, pH and trophic state index (TSI. The study demonstrated that density and composition of protozooplanktonic species and groups of the reservoir suffered seasonal variation due to the environmental variables (mainly temperature, turbidity, water transparency, dissolved oxygen and TSI and the biological variables (e.g. morphological characteristics, eating habits and escape strategies from predation of the species.

  15. Seasonal Variation in Groundwater Quality of Yavatmal District, India

    Directory of Open Access Journals (Sweden)

    P. N. Rajankar

    2011-01-01

    Full Text Available Seventy samples of groundwater were collected from different parts of Yavatmal District, India and analyzed. The results of this analysis were compared with the WHO water quality standards. The groundwater quality in this district showed slightly seasonal variation while the data computed in Water Quality Index (WQI calculator. The WQI was varied from 73.0 to 80.2 during pre monsoon and 68.7 to 72.4 in post monsoon season, which showed slightly seasonal variation. This may be attributed to surface runoff and percolation process. The results showed that, the water in these areas are bacteriologically not safe and need treatment before it is used for drinking.

  16. Seasonal variation of the South Indian tropical gyre

    NARCIS (Netherlands)

    Aguiar-González, B.; Ponsoni, Leandro; Ridderinkhof, H.; van Aken, H.M.; de Ruijter, W.P.M.; Maas, L.R.M.

    2016-01-01

    Based on satellite altimeter data and global atlases of temperature, salinity, wind stress and wind-driven circulation we investigate the seasonal variation of the South Indian tropical gyre and its associated open-ocean upwelling system, known as the Seychelles–Chagos Thermocline Ridge (SCTR).

  17. Seasonal variation of the South Indian tropical gyre

    NARCIS (Netherlands)

    Aguiar-González, B.; Ponsoni, Leandro; Ridderinkhof, H.; van Aken, H.M.; de Ruijter, W.P.M.; Maas, L.R.M.

    2016-01-01

    Based on satellite altimeter data and global atlases of temperature, salinity, wind stress and wind-driven circulation we investigate the seasonal variation of the South Indian tropical gyre and its associated open-ocean upwelling system, known as the Seychelles–Chagos Thermocline Ridge (SCTR). Resu

  18. Seasonal variation in imposex intensity of Thais clavigera

    Institute of Scientific and Technical Information of China (English)

    LI Zhengyan

    2005-01-01

    Imposex,specifically caused by TBT pollution,refers to the superimposition of male sexual characteristics in gastropod females.Seasonal variation of imposex intensity in Thais clavigera from both slightly and severely contaminated sites in Hong Kong waters was studied from 1988 to 1999. The male penis length showed significant difference between both sites and seasons. It was shortest during late autumn and early winter (October to December) and longest during spring and early summer (February to June). Female penis length also showed significant difference between sites. It did not change seasonally, however. The RPS (Relative Penis Size) index was the highest during autumn and early winter, and the lowest during spring and early summer. The VDS (Vas Deferens Sequence) index remained stable throughout the sampling period. This study showed that VDS index is a better indicator when we compare relative intensity of imposex. The comparison can only be meaningful provided the samples from different locations are taken during the same season.

  19. Seasonal variations of lipid content and composition in Perna viridis.

    Science.gov (United States)

    Li, Duo; Zhang, Yonghua; Sinclair, Andrew J

    2007-08-01

    The total lipid content, composition of main lipid classes, composition of sterols and composition of fatty acids in the main glycerolipids of Perna viridis were analyzed through four seasons using TLC-FID and GLC. Mussel samples were collected during different seasons between 2003 and 2004 from Shengsi Island, Zhejiang Province, China and stored frozen prior to freeze-drying and lipid extraction. Ten grams of dried mussel powder of each season were analyzed. Total lipid content ranged from 14.5 g/100 g in spring month to 7.8 g/100 g dried mussel powder in autumn month. The predominant lipid in spring month was triacylglycerol (TAG), however, in the other three seasons the phospholipids (PL) was the main lipid class. The most abundant fatty acid in TAG, PL and phosphatidylcholine (PC) was 16:0, with the summer samples having the highest proportion (24-30% of total fatty acid) and winter the lowest (14-22%). In phosphatidylethanolamine (PE), the spring samples had the highest proportions of 16:0. The predominant polyunsaturated fatty acids (PUFA) were 22:6n-3 and 20:5n-3 in TAG, PL, PE and PC (25-40%). The proportions of 22:6n-3 and 20:5n-3 were higher in spring than in other seasons in PL and PE. There were nine sterols identified, with cholesterol being the predominant sterol, and other main ones were desmostersol/brassicasterol and 24-methylenecholesterol. Proportions of other fatty acids in different lipid fractions and the sterol compositions as well also varied seasonally. There were subject to the seasonal variations. Differences in lipid content and composition, fatty acid composition in different lipid fractions may be caused by multiple factors such as lifecycle, sex, variation of plankton in different seasons and temperature, which could influence physiological activities and metabolism.

  20. Seasonal variation in detection of esophageal eosinophilia and eosinophilic esophagitis

    Science.gov (United States)

    Jensen, Elizabeth T.; Shah, Neil D.; Hoffman, Kate; Sonnenberg, Amnon; Genta, Robert M.; Dellon, Evan S.

    2015-01-01

    Summary Background Seasonal variation has been reported in diagnosis of eosinophilic esophagitis (EoE), but results are not consistent across studies and there are no national-level data in the United States. Aim To determine if there is seasonal variation in diagnosis of esophageal eosinophilia and EoE in the U.S., while accounting for factors such as climate zone and geographic variation. Methods This was a cross-sectional study using a U.S. national pathology database. Patients with esophageal eosinophilia (≥15 eosinophils per high-power field) comprised the primary case definition and were compared to those with normal esophageal biopsies. We calculated the crude and adjusted odds of esophageal eosinophilia by season, as well as by day of the year. Sensitivity analyses were performed using more restrictive case definitions of EoE, and after stratification by climate zone. Results 14,524 cases with esophageal eosinophilia and 90,459 normal controls were analyzed. The adjusted odds of esophageal eosinophilia were higher in the late spring and summer months, with the highest odds in July (aOR 1.13; 95%CI: 1.03–1.24). These findings persisted with increasing levels of esophageal eosinophilia, as well as across EoE case definitions. Seasonal variation was strongest in temperate and cold climates, and peak diagnosis varied by climate zone. Conclusions There is a mild but consistent seasonal variation in the diagnosis of esophageal eosinophilia and EoE, with cases more frequently diagnosed during summer months. These findings take into account climate and geographic differences, suggesting that aeroallergens may contribute to disease development or flare. PMID:26059636

  1. Seasonal Variation in Arsenic Speciation in a Shallow Aquifer

    Science.gov (United States)

    Illera, V.; O'Day, P. A.; Root, R. A.; Rivera, N.; Rafferty, M. T.; Vlassopoulos, D.

    2007-12-01

    Seasonal variation in arsenic speciation and concentration in sediments in a shallow aquifer were studied with respect to changes in water table elevation and rainfall. Sediment cores were collected at different times from 2004 to 2007 at a marsh site adjacent to San Francisco Bay (in East Palo Alto, CA), which experiences a strong wet winter/dry summer seasonality. The site is a former pesticide manufacturing plant that has undergone remediation and surface capping. Mobilization of post-remediation residual arsenic in sediments is inhibited by natural subsurface attenuation. This study examines the dynamics of seasonal changes on groundwater level and subsurface redox conditions, and its potential impact on arsenic mobilization. Cores (3-cm diameter) were collected from depths of 2.7-3.5 m, intersecting the range of seasonal elevation change in the water table. Groundwater level from a nearby well was monitored with continuous data logging. Sediment samples were analyzed for total and extractable element concentrations and characterized by arsenic and iron synchrotron X-ray absorption spectroscopy (XANES and EXAFS). Three distinct redox zones are recognized spectroscopically within the shallow aquifer: a reduced zone in unsaturated sediments (~0.5-1.5 m depth) where arsenic is present as As-sulfide phases (orpiment or realgar); a transition zone between reduced and oxidized zones at the depth of water table (~1.5 m ±0.5 m) with mixed arsenic oxidation states; and an oxidized zone permeated with oxic groundwaters (~1.5-3 m depth) where only As(V) is present. Sediment samples from the reduced zone had arsenic concentrations from 50 to 150 mg kg-1. Arsenic concentrations decreased to a minimum in the transition zone to 20 mg kg-1, and reached a maximum in the oxidized zone (around 200 mg kg-1). Arsenic XANES spectra showed a progressive change from mostly arsenic sulfides in the upper reduced sediments (component sum ~100%\\) to a mixture of orpiment and As

  2. Distribution and Seasonal Variation of Halocline in the World Ocean

    Science.gov (United States)

    Ueno, H.; Yasui, K.

    2014-12-01

    The distribution and seasonal variation in the halocline in the world ocean were investigated using a simple halocline definition. The halocline was observed in the tropics, equatorward subtropical regions, and subpolar regions, but it was absent in the central subtropical regions. A strong halocline tended to occur in the area where sea surface salinity (SSS) was low. The seasonal variation in halocline strength was also correlated with variation in SSS. The correlation coefficient was mostly negative; the halocline was strong when the SSS was low. However, in the Gulf of Alaska in the northeastern North Pacific, the correlation coefficient was positive. There, the halocline was strong when the SSS was high probably due to entrainment effect.

  3. SEASONAL MODULE DYNAMICS IN SARGASSUM SUBREPANDUM (FUCALES, PHAEOPHYTA)(1).

    Science.gov (United States)

    Ateweberhan, Mebrahtu; Bruggemann, J Henrich; Breeman, And Anneke M

    2008-04-01

    Module dynamics of the fucoid alga SARGASSUM SUBREPANDUM (Forssk.) C. Agardh was studied in the southern Red Sea. Seasonal variation in thallus density and size was determined, and the initiation, growth, reproduction, and shedding of modules (primary laterals) were ascertained, using a tagging approach. Possible effects of different size-related parameters on module initiation, growth, reproduction, and shedding were analyzed in the context of contradicting results for other macroalgae, in comparison with terrestrial plants. Thallus density varied little; most of the seasonal variation occurred at the modular level. A restricted period of new module formation early in the cooler season was followed by fast growth and reproduction. Massive shedding of modules occurred toward the end of the cooler season leading to strongly reduced biomass in summer. There was some evidence that high module numbers inhibited new module formation and enhanced the maximum module elongation rate (fastest-growing module per thallus). On the other hand, elongation rates generally decreased, and apical tissue losses increased with increasing module length. This response was observed over a wide size range, suggesting grazing losses. There was no evidence of suppressed growth in small modules due to intraspecific competition. Elongation rates remained unaffected by reproductive status, indicating that there was no direct trade-off between growth and reproduction. Module survivorship was independent of module number and size, but fertile modules were more persistent than vegetative ones. We conclude that module dynamics are determined by seasonal changes in the environment, size-dependent processes, and interactions among the modules. © 2008 Phycological Society of America.

  4. Sensory Profiles and Seasonal Variation of Black Walnut Cultivars.

    Science.gov (United States)

    Lynch, Catherine; Koppel, Kadri; Reid, William

    2016-03-01

    Black walnut (Juglans nigra L.) is a North American hardwood tree valued for producing nuts and wood. Black walnut cultivars were evaluated by a trained panel over 2 growing seasons to determine the seasonal variation in the sensory profile. Results showed that cultivars were significantly different on 3 appearance (skin color, nutmeat color, and kernel roughness), 1 aroma (black walnut ID), 5 flavor (black walnut ID, banana-like, piny, rancid, and overall nutty), and 2 texture attributes (surface roughness and hardness). These profiles were compared to results collected in 2011 to determine differences between growing seasons. Results showed 4 flavor attributes (black walnut ID, overall nutty, fruity-dark and rancid) had an interaction effect of year and cultivar, while 6 attributes (brown, caramelized, floral/fruity, piny, musty/dusty, and oily) showed a main effect of year. In general, flavor attributes had higher intensities in 2011 than in 2013. These results suggest that seasonal variation may influence flavor profile more than cultivar. Thus, using samples from only 1 growing season when testing agricultural products may not provide adequate information for the long term. © 2016 Institute of Food Technologists®

  5. SEASONAL VARIATIONS OF THE TROPICAL INTRASEASONAL OSCILLATION AND ITS REPRODUCTION IN SAMIL-R42L9

    Institute of Scientific and Technical Information of China (English)

    JIA Xiao-long; LI Chong-yin

    2007-01-01

    Seasonal variations of the tropical intraseasonal oscillation (ISO) and relationship to seasonal variation of the climate background are studied by using NCEP/NCAR reanalysis data and output of SAMIL-R42L9. Analysis of NCEP data shows that spatial distribution of the tropical ISO has obvious seasonal variations, which are well consistent with the seasonal variation of climate background. The activity of the tropical ISO is, to a great extent, dependent on warm SST, strong convection, zonal western wind, strong precipitation and low-level moisture convergence. Main characteristics of the seasonal variations of the tropical ISO are captured by SAML-R42L9. Simulations of seasonal variation of climate background vary greatly with different variables. Results of SAMIL-R42L9 indicate that the seasonal variations of the tropical ISO in dynamical fields are more dependent on climate background than in heating fields and SAMIL-R42L9 cannot represent well the strong dependence of the ISO on the climate background present in NCEP/NCAR reanalysis data. It also suggests that seasonal variations of the ISO do not completely depend on that of climate background.

  6. Seasonal variations in fouling diatom communities on the Yantai coast

    Science.gov (United States)

    Yang, Cuiyun; Wang, Jianhua; Yu, Yang; Liu, Sujing; Xia, Chuanhai

    2015-03-01

    Fouling diatoms are a main component of biofilm, and play an important role in marine biofouling formation. We investigated seasonal variations in fouling diatom communities that developed on glass slides immersed in seawater, on the Yantai coast, northern Yellow Sea, China, using microscopy and molecular techniques. Studies were conducted during 2012 and 2013 over 3, 7, 14, and 21 days in each season. The abundance of attached diatoms and extracellular polymeric substances increased with exposure time of the slides to seawater. The lowest diatom density appeared in winter and the highest species richness and diversity were found in summer and autumn. Seasonal variation was observed in the structure of fouling diatom communities. Pennate diatoms Cylindrotheca, Nitzschia, Navicula, Amphora, Gomphonema, and Licmophora were the main fouling groups. Cylindrotheca sp. dominated in the spring. Under laboratory culture conditions, we found that Cylindrotheca grew very fast, which might account for the highest density of this diatom in spring. The lower densities in summer and autumn might result from the emergence of fouling animals and environmental factors. The Cylindrotheca sp. was identified as Cylindrotheca closterium using18S rDNA sequencing. The colonization process of fouling diatoms and significant seasonal variation in this study depended on environmental and biological factors. Understanding the basis of fouling diatoms is essential and important for developing new antifouling techniques.

  7. Seasonal variation of carbon uptake in a primary forest ecosystem in southwestern Amazon

    Science.gov (United States)

    Garcia, S.; Gonçalves, J. F.; Cirino, G. G.; Artaxo, P.

    2013-05-01

    Tropical rainforests possess a large carbon stock and their dynamics are strongly dependent on climatic factors. Carbon assimilation by tropical forests can be meaningfully altered by seasonal changes in rainfall regime. Considering the interactions of the plant-atmosphere system, this study evaluated the effect of the precipitation seasonality on the photosynthesis of a primary forest, located in the state of Rondônia (Rebio Jaru), southwest of the Amazon, Brazil. Precipitation data from Instituto Nacional de Metereologia (INMET) from five years (2006-2010) were analyzed and the NEE (Net Ecosystem Exchange) of CO2 was calculated for ten years (1999-2009) using data from the Large Scale Biosphere-Atmosphere Experiment in the Amazon (LBA). Furthermore, leaves gas exchanges were measured in 48 individual in three forest strata (canopy, sub-canopy and understory) using a infrared gas analyzer (IRGA model LI-6400, Li-cor, USA) during two distinct precipitation periods: at the end of the wet (May) and dry (Sept.) seasons. The climatological data exhibited an accentuated dry season between the months of June and August. The lower water availability inhibited the forest primary production and altered the CO2 assimilation observed in the variation in the NEE values (Fig. 1). The NEE values were larger in the dry season and showed a smaller carbon uptake in the ecosystem, when compared with the values from the wet season. In the period that succeeds the dry season, the photosynthetic rates measured in canopy leaves were 44,49% lower than the values measured in the period prior to the dry season. Therefore, it is possible to conclude that the accentuated dry season strongly controls the seasonal photosynthesis variation in the studied area, decreasing the carbon uptake into the ecosystem. Fig. 1: Seasonal cycle of Net Ecosystem Exchange (NEE) of CO2 between the forest and atmosphere, in Rebio Jaru (1999-2009, monthly averages).

  8. Seasonal variations in urinary risk factors among patients with nephrolithiasis

    Science.gov (United States)

    Hill, K.; Poindexter, J.; Pak, C. Y.

    1991-01-01

    Twenty-four hour urine specimens from 5,677 stone-forming patients throughout the United States were analyzed for seasonal variations in urinary risk factors for nephrolithiasis. Determinations were performed for urine volume, pH, calcium, oxalate, phosphorus, sodium, magnesium, citrate, sulfate, uric acid, and the relative supersaturation (RS) of calcium oxalate, brushite, monosodium urate, and uric acid. Criteria for significant seasonal variation included a significant difference in monthly means of risk factors, seasonal grouping of the data by the Student-Newman-Keuls multiple range test, consistent year-to-year trends and a physiologically significant range. Minimum urine volume of 1.54 +/- 0.70 SD L/day occurred in October while a maximum urine volume of 1.76 +/- 0.78 SD L/day was observed during February. Minimum urine pH of 5.94 +/- 0.64 SD was observed during July and August while a maximum pH of 6.18 +/- 0.61 SD was observed during February. Daily urinary excretion of sodium was lowest during August, 158 +/- 74 SD mEq/day and highest during February 177 +/- 70 SD mEq/day. The RS of brushite and uric acid were found to display significant pH-dependent seasonal variation with a maximum RS of uric acid 2.26 +/- 1.98 SD in June and a low of 1.48 +/- 1.30 SD in February. Maximum RS of brushite 2.75 +/- 2.58 was observed during February. Minimum RS of brushite 1.93 +/- 1.70 SD was observed in June. Phosphorus excretion displayed seasonal variation about a spring-fall axis with a maximum value 1042 +/- 373 SD mg/day in April and a minimum value of 895 +/- 289 SD mg/day. Urine volume, sodium, and pH were significantly lower during the summer (June, July, August) than in the winter (December, January, February). The RS of uric acid was higher, but that of brushite and monosodium urate was lower in the summer than in the winter. The seasonal changes observed in urine volume, pH, sodium, and the RS of brushite and uric acid are consistent with summertime sweating

  9. Seasonal variation of the onset of preeclampsia and eclampsia

    Directory of Open Access Journals (Sweden)

    Ziba Zahiri

    2007-08-01

    Full Text Available

    BACKGROUND: Preeclampsia is one of the three leading causes of maternal mortality. Studies have suggested that the incidence of preeclampsia may be partially dependent on the month or season of delivery. This study was conducted to evaluate whether seasonal variation has any effect on the incidence of eclampsia or preeclampsia.
    METHODS: From 1999 to 2001, a cross-sectional study in Alzahra Hospital was performed using all deliveries with gestational age more than 20 weeks. Variables of maternal age, parity, occurrence of preeclampsia and eclampsia, and season were evaluated and analyzed by chi-square test in SPSS 10.
    RESULTS: During the period of the study, there were 12,142 deliveries at Alzahra Hospital in Rasht. There were 2,579 (21.3% deliveries in spring, 2,696 (22.2% in summer, 3,645 (30% in autumn, and 3,222 (26.5% in winter. There was no statistically significant relationship between the age, parity and season. Hypertensive disorder was reported in 609 pregnancies (5%, with 11,533 (95% having no hypertensive disorder. Data showed that 397 patients (3.3% had preeclampsia and eclampsia. The highest rate of preeclampsia was in spring (3.6%, and the lowest rate was in summer (3%, but it revealed no statistical difference in the incidence of preeclampsia with season.
    CONCLUSIONS: We found no correlation between preeclampsia or eclampsia and season. It may be due to relative similarities between seasons in North of Iran. For example, there are relative similarities between spring and summer, and between autumn and winter.
    KEY WORDS: Pregnancy-induced hypertension, preeclampsia, eclampsia, seasonal.

  10. Serological Evidence Of Seasonal Variation Of Enteric Fevers

    Directory of Open Access Journals (Sweden)

    Damle A S

    1985-01-01

    Full Text Available An attempt has been made to find out seasonal variation of enteric fever in this rural part of Maharastra. Diagnostic rise in antibodies against Salmonellae and clinical correlation was used to label the febrile cases as enteric fever cases over a period of six years. 4042 Samples were tested by Nidal reaction for rise in anti Salmonella antibodies. Of these 1236 (30% showed significant (diagnostic rise in antibody levels. Season wise study of these cases over the six years indicates that maximum number of enteric fever cases occur in rainy season followed by winter and summer. Chi-square test has been applied to find out statistical significance of these findings.

  11. Seasonal variations of antioxidants in the brown seaweed Saccharina latissima

    DEFF Research Database (Denmark)

    Sørensen, Ann-Dorit Moltke; Safafar, Hamed; Pedersen, Anja

    Mainly the brown seaweeds are known for their high antioxidative capacity within the specific compounds such as phlorotannins, polyphenols, flavonoids, pigments, and these natural antioxidants are of high industrial interest. Previous studies have shown large seasonal variations in biomass...... composition. The aim of this study was to see if there was a seasonal variation in the antioxidant content of sugar kelp (Saccharina latissima), compare two cultivation sites, REF and IMTA, and test different solvents applied for extractions, methanol or ethyl acetate. Rope cultivated sugar kelp were sampled....... The biological variability had a high impact revealed by large standard deviation. The pigment specimens did not change during the year, however the concentration did, and with fucoxanthin as the most interesting. No clear correlation was found between pigments and the antioxidants. This study showed high...

  12. Seasonal variation in stable carbon and nitrogen isotope values of bats reflect environmental baselines.

    Directory of Open Access Journals (Sweden)

    Ana G Popa-Lisseanu

    Full Text Available The stable carbon and nitrogen isotope composition of animal tissues is commonly used to trace wildlife diets and analyze food chains. Changes in an animal's isotopic values over time are generally assumed to indicate diet shifts or, less frequently, physiological changes. Although plant isotopic values are known to correlate with climatic seasonality, only a few studies restricted to aquatic environments have investigated whether temporal isotopic variation in consumers may also reflect environmental baselines through trophic propagation. We modeled the monthly variation in carbon and nitrogen isotope values in whole blood of four insectivorous bat species occupying different foraging niches in southern Spain. We found a common pattern of isotopic variation independent of feeding habits, with an overall change as large as or larger than one trophic step. Physiological changes related to reproduction or to fat deposition prior to hibernation had no effect on isotopic variation, but juvenile bats had higher δ13C and δ15N values than adults. Aridity was the factor that best explained isotopic variation: bat blood became enriched in both 13C and 15N after hotter and/or drier periods. Our study is the first to show that consumers in terrestrial ecosystems reflect seasonal environmental dynamics in their isotope values. We highlight the danger of misinterpreting stable isotope data when not accounting for seasonal isotopic baselines in food web studies. Understanding how environmental seasonality is integrated in animals' isotope values will be crucial for developing reliable methods to use stable isotopes as dietary tracers.

  13. Seasonal Variation on the Proximate Composition of Turbo brunneus

    Directory of Open Access Journals (Sweden)

    R. Ramesh

    2008-01-01

    Full Text Available This study is to find out the nutritive value of the meat of T. brunneus and to ascertain the relationship between seasonal variations in biochemical components and reproductive cycle. The monthly variations in the biochemical constituents were estimated in different body organs such as foot, gonad, digestive gland and mantle for both male and female gastropods. Carbohydrate content of gonad is high during May 2002 in males (5.30% and females (6.14%. The percentage of lipid is high (4.85% in ovary during May 2002 and low in October 2002 (3.10%. In testis, the values range from 3.0 (September 2002 to 4.20% (May 2002, respectively. The gonadal tissues show major variations in lipid values, whereas the percentage variation is negligible in mantle, which ranges from 1.64-1.74% in males and 1.59-1.78% in females. The lipid valued decreases from June to October and the values showed little fluctuations from the minimum value until December. But, in the digestive gland, the percentage is higher in September 2002 in males (3.06% and October 2003 in females (2.96% and low in May 2003 (2.4 and 2.12% in both the sexes. The protein contents of the digestive gland shows a clear seasonal variation, which is negatively correlated with that of other body organs.

  14. Human birth seasonality: latitudinal gradient and interplay with childhood disease dynamics

    OpenAIRE

    Martinez-Bakker, Micaela; Bakker, Kevin M.; King, Aaron A.; Rohani, Pejman

    2014-01-01

    More than a century of ecological studies have demonstrated the importance of demography in shaping spatial and temporal variation in population dynamics. Surprisingly, the impact of seasonal recruitment on infectious disease systems has received much less attention. Here, we present data encompassing 78 years of monthly natality in the USA, and reveal pronounced seasonality in birth rates, with geographical and temporal variation in both the peak birth timing and amplitude. The timing of ann...

  15. Seasonal variation in energy balance and canopy conductance for a tropical savanna ecosystem of south-central Mato Grosso, Brazil

    Science.gov (United States)

    Rodrigues, T. R.; Vourlitis, G. L.; Lobo, F. D.; de Oliveira, R. G.; Nogueira, J. D.

    2013-12-01

    Tropical savanna (locally known as cerrado) comprises 24% of Brazil and is characterized by high temporal (climatic) and spatial (land cover) variation, biodiversity, and human activity. However, temporal variations in energy exchange are poorly understood, especially for mixed-grasslands (locally known as campo-sujo), making current and future patterns of energy balance highly uncertain. We used eddy covariance to measure latent (Le) and sensible (H) heat flux of a mixed-grassland, and linked meteorological and remote-sensing data to determine the controls on these fluxes. We hypothesized that (1) seasonal variations in H and Le would be large due to variations in precipitation, (2) ecosystem phenology, estimated using the Enhanced Vegetation Index (EVI), would be the best predictor of seasonal variation in Le, and (3) cerrado, transitional, and humid evergreen forests would have similar rates of average annual Le despite large seasonal variation in cerrado Le. We found that campo-sujo exhibits large seasonal fluctuations in energy balance that are driven by rainfall, and that responses to rainfall pulses are rapid and dynamic, especially during the dry season. Seasonal variations in the EVI did not affect energy fluxes; however, when energy fluxes were normalized with net radiation (Rn), the EVI was found to significantly affect the amount of available energy dissipated by H, Le, and G, indicating an important ground surface feedback on energy partitioning. Compared to other tropical ecosystems, cerrado exhibited substantially more seasonal variation in energy flux density than forested tropical ecosystems. For example, cerrado had lower rates of Le during the dry season, due to water limitations, but higher rates of wet-season Le than tropical forests, which were likely limited by radiation due to frequent cloud cover. Overall, these seasonal variations caused average annual rates of Le to be similar between cerrado, transitional, and humid evergreen forests.

  16. Methane Fluxes from the Pantanal Floodplain in Brazil. Seasonal Variation

    Energy Technology Data Exchange (ETDEWEB)

    Alvala, P.C.; Kirchhoff, V.W.J.H. [Instituto Nacional de Pesquisas Espaciais, S. Paulo (Brazil)

    2000-07-01

    A total of 15 campaigns were performed during 1997 and 1998 in a lake inside the Pantanal region, near the Miranda River using the static chamber technique to determine methane fluxes. Air samples were collected in stainless steel canisters and analyzed by gas chromatography, with a FID detector. A distinct seasonal variation has been found, with much higher emissions during the wet season, and comparatively lower emissions during the dry season, but with large variability. Individual fluxes had variations from less than 1 to 1,389 mgCH4m{sup -2}d{sup -1}. The average for the period of high fluxes, from October to April was 238 {+-}238 mgCH4m{sup -2}d{sup -1}, and for the period of lower fluxes, from May to September, the average was 7 {+-}14mgCH4m{sup -2}d{sup -1}. Methane fluxes were correlated with the precipitation in the region, but with a poor statistics. 8 refs.

  17. Seasonal variation in the onset of acute pancreatitis

    Institute of Scientific and Technical Information of China (English)

    Massimo Gallerani; Benedetta Boari; Raffaella Salmi; Roberto Manfredini

    2004-01-01

    AIM: A circannual variation in the onset of several acute diseases,mostly dealing with cardiovascular system, has been reported.The present study was to verify the possible existence of a seasonal variability in the onset of acute pancreatitis.METHODS: All patients consecutively admitted to the Hospital of Ferrara, Italy, between January 1998 to December 2002,whose discharge diagnosis was acute pancreatitis, were considered. According to the time of admission, cases were categorized into twelve 1-mo intervals and in four periods by season. x2 test for goodness of fit and partial Fourier series were used for statistical analysis.RESULTS: During the study period, 549 cases of acute pancreatitis were observed. A significant peak of higher incidence was found in March-May, both for total population,males and subgroups with and without cholelithiasis or alcoholism. Fourier analysis showed the existence of a circannual rhythmic pattern with its main peak in March (95%C.L.: February-April, P = 0.005), and a secondary one in September. Death occurred more frequently in DecemberFebruary, compared to the other periods (P = 0.029), and chronobiologic analysis yielded a seasonal peak in NovemberDecember (P<0.001).CONCLUSION: This study shows the existence of a circannual variation in the onset of acute pancreatitis, with a significanty higher frequency of events in the spring, especially for patients with cholelithiasis or alcoholism. Moreover, events occurring during the colder months seem to be characterized by a higher mortality rate.

  18. Seasonal variations of halite saturation in the Dead Sea

    Science.gov (United States)

    Sirota, Ido; Arnon, Ali; Lensky, Nadav G.

    2016-09-01

    Hypersaline lakes and seas were common in the past, precipitating thick evaporitic salt deposits. The only modern analogue for the paleolimnology of deep salt-saturated aquatic environments exists in the Dead Sea. In this study, we present new insights from the Dead Sea on the role of seasonal thermohaline stratification and water balance on the seasonal and depth variations of the degree of saturation of halite (salt) and the rate of halite growth along the water column. We developed methodologies to accurately determine the empirical degree of halite saturation of the lake based on high accuracy densitometry, and to quantify halite growth rate along the water column. During summer, the epilimnion is undersaturated and halite is dissolved, whereas during winter the entire water column is supersaturated and crystallizes halite. This result is not trivial because the variations in the water balance suggest the opposite; summer is associated with higher loss of water by evaporation from the lake compared to the winter. Hence, the thermal effect overcomes the hydrological balance effect and thus governs the seasonal saturation cycle. The hypolimnion is supersaturated with respect to halite and crystallizes throughout the year, with higher super saturation and higher crystallization rates during winter. During summer, simultaneous opposing environments coexist—an undersaturated epilimnion that dissolves halite and a supersaturated hypolimnion that crystallizes halite, which results in focusing of halite deposits in the deep hypolimnetic parts of the evaporitic basins and thinning the shallow epilimnetic deposits.

  19. Seasonal variations in physical activity and implications for human health.

    Science.gov (United States)

    Shephard, Roy J; Aoyagi, Yukitoshi

    2009-10-01

    This review explores the implications of seasonal changes in physical activity for fitness and human health. Photosensitivity and nutrient shortages mediate animal hibernation via the hypothalamus and changes in leptin and ghrelin concentrations. Opportunities for hunting and crop cultivation determine seasonal activity in under-developed human societies, but in developed societies temperature and rainfall are dominant influences, usually over-riding innate rhythms. Both questionnaire data and objective measurements show that many groups from children to the elderly increase their physical activity from winter to spring or summer. Measurements of maximal oxygen intake and muscle strength commonly show parallel seasonal changes. However, potential effects upon body mass and body fat may be counteracted by changes of food intake; subsistence agriculturists sometimes maintain or increase physical activity at the expense of a decrease in body mass. In developed societies, body fat commonly increases during the winter, with parallel changes in blood lipids, blood pressure and blood coagulability; moreover, these changes are not always fully reversed the following summer. Most developed societies show increased all-cause and cardiac mortalities in the winter. Health consequences of seasonal variations in physical activity including an increased vulnerability to cardiac catastrophe and a year-by-year increase in total body fat seem most likely if the average level of physical activity for the year is low. Public health recommendations should underline the importance of maintaining physical activity during adverse environmental conditions by adapting clothing, modifying behaviour and exploiting any available air-conditioned indoor facilities.

  20. Seasonal variations in vertical migration of glacier lanternfish, Benthosema glaciale

    KAUST Repository

    Dypvik, Eivind

    2012-06-05

    The seasonal variations in glacier lanternfish (Benthosema glaciale) vertical distribution and diel vertical migration (DVM) were studied by use of a bottom-mounted upward-facing 38 kHz echo sounder deployed at 392 m depth and cabled to shore in Masfjorden (~6052?N, ~524?E), Norway. Acoustic data from July 2007-October 2008 were analyzed, and scattering layers below ~220 m during daytime were attributed to glacier lanternfish based on net sampling in this, and previous studies, as well as from analysis of the acoustic data. At these depths, three different diel behavioral strategies were apparent: normal diel vertical migration (NDVM), inverse DVM (IDVM), and no DVM (NoDVM). NoDVM was present all year, while IDVM was present in autumn and winter, and NDVM was present during spring and summer. The seasonal differences in DVM behavior seem to correlate with previously established seasonal distribution of prey. We hypothesize that in regions with seasonally migrating zooplankton, such as where calanoid copepods overwinter at depth, similar plasticity in DVM behavior might occur in other populations of lanternfishes. 2012 The Author(s).

  1. Seasonal leaf dynamics for tropical evergreen forests in a process-based global ecosystem model

    Science.gov (United States)

    De Weirdt, M.; Verbeeck, H.; Maignan, F.; Peylin, P.; Poulter, B.; Bonal, D.; Ciais, P.; Steppe, K.

    2012-09-01

    The influence of seasonal phenology on canopy photosynthesis in tropical evergreen forests remains poorly understood, and its representation in global ecosystem models is highly simplified, typically with no seasonal variation of canopy leaf properties taken into account. Including seasonal variation in leaf age and photosynthetic capacity could improve the correspondence of global vegetation model outputs with the wet-dry season CO2 patterns measured at flux tower sites in these forests. We introduced a leaf litterfall dynamics scheme in the global terrestrial ecosystem model ORCHIDEE based on seasonal variations in net primary production (NPP), resulting in higher leaf turnover in periods of high productivity. The modifications in the leaf litterfall scheme induce seasonal variation in leaf age distribution and photosynthetic capacity. We evaluated the results of the modification against seasonal patterns of three long-term in-situ leaf litterfall datasets of evergreen tropical forests in Panama, French Guiana and Brazil. In addition, we evaluated the impact of the model improvements on simulated latent heat (LE) and gross primary productivity (GPP) fluxes for the flux tower sites Guyaflux (French Guiana) and Tapajós (km 67, Brazil). The results show that the introduced seasonal leaf litterfall corresponds well with field inventory leaf litter data and times with its seasonality. Although the simulated litterfall improved substantially by the model modifications, the impact on the modelled fluxes remained limited. The seasonal pattern of GPP improved clearly for the Guyaflux site, but no significant improvement was obtained for the Tapajós site. The seasonal pattern of the modelled latent heat fluxes was hardly changed and remained consistent with the observed fluxes. We conclude that we introduced a realistic and generic litterfall dynamics scheme, but that other processes need to be improved in the model to achieve better simulations of GPP seasonal patterns

  2. Seasonal leaf dynamics for tropical evergreen forests in a process-based global ecosystem model

    Directory of Open Access Journals (Sweden)

    M. De Weirdt

    2012-09-01

    Full Text Available The influence of seasonal phenology on canopy photosynthesis in tropical evergreen forests remains poorly understood, and its representation in global ecosystem models is highly simplified, typically with no seasonal variation of canopy leaf properties taken into account. Including seasonal variation in leaf age and photosynthetic capacity could improve the correspondence of global vegetation model outputs with the wet–dry season CO2 patterns measured at flux tower sites in these forests. We introduced a leaf litterfall dynamics scheme in the global terrestrial ecosystem model ORCHIDEE based on seasonal variations in net primary production (NPP, resulting in higher leaf turnover in periods of high productivity. The modifications in the leaf litterfall scheme induce seasonal variation in leaf age distribution and photosynthetic capacity. We evaluated the results of the modification against seasonal patterns of three long-term in-situ leaf litterfall datasets of evergreen tropical forests in Panama, French Guiana and Brazil. In addition, we evaluated the impact of the model improvements on simulated latent heat (LE and gross primary productivity (GPP fluxes for the flux tower sites Guyaflux (French Guiana and Tapajós (km 67, Brazil. The results show that the introduced seasonal leaf litterfall corresponds well with field inventory leaf litter data and times with its seasonality. Although the simulated litterfall improved substantially by the model modifications, the impact on the modelled fluxes remained limited. The seasonal pattern of GPP improved clearly for the Guyaflux site, but no significant improvement was obtained for the Tapajós site. The seasonal pattern of the modelled latent heat fluxes was hardly changed and remained consistent with the observed fluxes. We conclude that we introduced a realistic and generic litterfall dynamics scheme, but that other processes need to be improved in the model to achieve better

  3. Body mass affects seasonal variation in sickness intensity in a seasonally breeding rodent

    Science.gov (United States)

    Carlton, Elizabeth D.; Demas, Gregory E.

    2015-01-01

    ABSTRACT Species that display seasonal variation in sickness intensity show the most intense response in the season during which they have the highest body mass, suggesting that sickness intensity may be limited by an animal's energy stores. Siberian hamsters (Phodopus sungorus) display lower body masses and less intense sickness when housed in short, winter-like days as opposed to long, summer-like days. To determine whether reduced sickness intensity displayed by short-day hamsters is a product of seasonal changes in body mass, we food restricted long-day hamsters so that they exhibited body mass loss that mimicked the natural photoperiod-induced loss of body mass in short-day hamsters. We then experimentally induced sickness with lipopolysaccharide (LPS) and compared sickness responses among long-day food-restricted and long- and short-day ad libitum fed groups, predicting that long-day food-restricted hamsters would show sickness responses comparable to those of short-day ad libitum fed hamsters and attenuated in comparison to long-day ad libitum fed hamsters. We found that long-day food-restricted hamsters showed attenuated LPS-induced anorexia, loss of body mass and hypothermia compared with long-day ad libitum fed animals; however, anorexia remained elevated in long-day food-restricted animals compared with short-day ad libitum fed animals. Additionally, LPS-induced anhedonia and decreases in nest building were not influenced by body mass. Results of hormone assays suggest that cortisol levels could play a role in the attenuation of sickness in long-day food-restricted hamsters, indicating that future research should target the roles of glucocorticoids and natural variation in energy stores in seasonal sickness variation. PMID:25852068

  4. Seasonal variations in the harpagoside content of Scrophularia scorodonia L.

    Science.gov (United States)

    De Santos Galíndez, J; Matellano, L F; Lanza, A M; Castillo, L V

    2000-01-01

    Seasonal variations on the content of harpagoside in Scrophularia scorodonia L. (Scrophulariaceae) were investigated using plants collected monthly from January to December in 1995. During growth of this species the percentage of harpagoside was the highest during the maximum development of the plant, specially in July. Harpagoside levels differed among leaves, stems and flowers of S. scorodonia. Leaves were distinguished from other plant parts by higher levels of harpagoside. Drying at ambient temperature influenced the yield of harpagoside compared with the results of plant drying by microwave.

  5. Spatial and seasonal variations of polycyclic aromatic hydrocarbons in Haihe Plain, China

    Energy Technology Data Exchange (ETDEWEB)

    Wang Rong [Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China); Cao Hongying, E-mail: caohy@igsnrr.ac.cn [Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101 (China); Li Wei; Wang Wei; Wang Wentao; Zhang Liwen; Liu Jiumeng; Ouyang Huiling; Tao Shu [Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China)

    2011-05-15

    A dynamic fugacity model was developed to simulate the spatial and seasonal variations of PAHs in Haihe Plain, China. The calculated and measured concentrations exhibited good consistency in magnitude with deviations within a factor of 4 in air and 2 in soil. The spatial distributions of PAHs in air were mainly controlled by emission while the seasonal variations were dominated by emission and gas-particle partition. In soil, the spatial distributions of PAHs were controlled by the soil organic carbon content while the seasonal variations were insignificant. The severest soil contamination was observed in Shanxi and followed by the southwest of Hebei province. Transfer fluxes of total PAHs between air and soil were calculated. The spatial distribution of air-to-soil flux was closely related to the landcover while the soil-to-air flux changed with soil organic matter content. Monte Carlo simulation was done to evaluate the uncertainty of the estimated results in air. - Highlights: > A Level IV dynamic model with spatial resolution was developed. > The model was applied to address the fate of PAHs in Haihe Plain, China. > The severest soil contamination was observed in Shanxi and followed by the southwest of Hebei province. > The air-to-soil flux was closely related to the landcover while the soil-to-air flux changed with soil organic matter content. > The model results proved to have less uncertainty than regular level IV model without spatial resolution. - Spatial and seasonal variations of PAHs in Haihe Plain were studied using a dynamic fugacity model with spatial resolution.

  6. Auroral Substorm Time Scales: Seasonal and IMF Variations

    Science.gov (United States)

    Chua, D.; Parks, G. K.; Brittnacher, M.; Germany, G. A.; Spann, J. F.; Six, N. Frank (Technical Monitor)

    2002-01-01

    The time scales and phases of auroral substorm, activity are quantied in this study using the hemispheric power computed from Polar Ultraviolet Imager (UVI) images. We have applied this technique to several hundred substorm events and we are able to quantify how the characterist act, of substorms vary with season and IMF Bz orientation. We show that substorm time scales vary more strongly with season than with IMF Bz orientation. The recovery time for substorm. activity is well ordered by whether or not the nightside oral zone is sunlit. The recovery time scales for substorms occurring in the winter and equinox periods are similar and are both roughly a factor of two longer than in summer when the auroral oval is sunlit. Our results support the hypothesis that the ionosphere plays an active role in governing the dynamics of the aurora.

  7. Seasonal Phytoplankton Dynamics in the Eastern Tropical Atlantic

    Science.gov (United States)

    Monger, Bruce; McClain, Charles; Murtugudde, Ragu

    1997-01-01

    The coastal zone color scanner (CZCS) that operated aboard the Nimbus 7 satellite provided extensive coverage of phytoplankton pigment concentrations in the surface waters of the eastern tropical Atlantic (ETA) from March 1979 to February 1980 and coincided with four major research cruises to this region. Total primary production within the ETA (5 deg N-10 deg S, 25 deg W-10 deg E) was determined from CZCS pigment estimates and an empirical algorithm derived from concurrent in situ data taken along 4 deg W that relates near-surface chlorophyll concentration and integrated primary production. We estimated an average annual production for the ETA of 2.3 Gt C/yr with an associated 3.5-fold seasonal variation in the magnitude of this production. We describe the principal physical mechanisms controlling seasonal phytoplankton dynamics within the ETA and propose that in addition to seasonal change in the thermocline depth, one must also consider changes in the depth of the equatorial under current. An extensive validation effort indicates that the standard CZCS global products are a conservative estimate of pigment concentrations in ETA surface waters. Significant underestimates by the CZCS global products were observed in June and July which we attributed, in part, to aerosol correction errors and, more importantly, to errors caused by a significant reduction in the concentration of near-surface dissolved organic matter that resulted from strong equatorial upwelling.

  8. Seasonal variations of dust record in the Muztagata ice cores

    Institute of Scientific and Technical Information of China (English)

    WU GuangJian; YAO TanDong; XU BaiQing; TIAN LiDe; LI Zhen; DUAN KeQin

    2008-01-01

    Based on the oxygen isotope ratio and microparticle record in ice cores recovered at Mt.Muztagata,Eastern Pamirs,the seasonal variations of atmospheric dust have been reconstructed for the past four decades.High dust concentrations and coarser particle grains have the similar trend with oxygen iso-tope value.Our statistical results indicate that 50%--60% high dust concentration samples occur dur-ing the season with high oxygen isotope values (summer),while low dust storm frequency during spring and winter.Back-trajectory analysis shows that the air mass hitting Muztagata predominately came from West Asia (such as Iran-Afghanistan Plateau) and Central Asia,which are the main dust source area for Muztagata.Dust storms in those source areas most frequently occur during summer (from May to August),while frequent dust storm events in northern China mainly occur during spring (March to May).Regions in the path of Asian dust transport,such as in Japan,the North Pacific,and Greenland,also show high dust concentrations during spring (from March to May).Our results indicate that dust storms have different seasonality in different regions within Asia.

  9. Latitudinal variations in seasonal activity of influenza and respiratory syncytial virus (RSV: a global comparative review.

    Directory of Open Access Journals (Sweden)

    Kimberly Bloom-Feshbach

    Full Text Available There is limited information on influenza and respiratory syncytial virus (RSV seasonal patterns in tropical areas, although there is renewed interest in understanding the seasonal drivers of respiratory viruses.We review geographic variations in seasonality of laboratory-confirmed influenza and RSV epidemics in 137 global locations based on literature review and electronic sources. We assessed peak timing and epidemic duration and explored their association with geography and study settings. We fitted time series model to weekly national data available from the WHO influenza surveillance system (FluNet to further characterize seasonal parameters.Influenza and RSV activity consistently peaked during winter months in temperate locales, while there was greater diversity in the tropics. Several temperate locations experienced semi-annual influenza activity with peaks occurring in winter and summer. Semi-annual activity was relatively common in tropical areas of Southeast Asia for both viruses. Biennial cycles of RSV activity were identified in Northern Europe. Both viruses exhibited weak latitudinal gradients in the timing of epidemics by hemisphere, with peak timing occurring later in the calendar year with increasing latitude (P<0.03. Time series model applied to influenza data from 85 countries confirmed the presence of latitudinal gradients in timing, duration, seasonal amplitude, and between-year variability of epidemics. Overall, 80% of tropical locations experienced distinct RSV seasons lasting 6 months or less, while the percentage was 50% for influenza.Our review combining literature and electronic data sources suggests that a large fraction of tropical locations experience focused seasons of respiratory virus activity in individual years. Information on seasonal patterns remains limited in large undersampled regions, included Africa and Central America. Future studies should attempt to link the observed latitudinal gradients in

  10. Assessment and seasonal variations of communicable diseases: 3 year study

    Directory of Open Access Journals (Sweden)

    D. Kalyani

    2016-04-01

    Results: Results showed that a total of 34,981 had been treated at the inpatient departments from the year 2011 to 2013. It was observed that communicable diseases constituted about 85% (30,082 of the total disease burden with viral infections being the commonest. Most of the diseases were observed to have a seasonal variation. The most common disease identified was viral fever 8713 (28.96%, secondly acute diarrheal diseases 7965(26.52% followed by enteric fever 2958 (9.83% and malaria 2443(8.12%. The least common were Rabies 80 (0.26 % and pertussis 37 (0.12%. Outbreaks of Measles and Diphtheria were also noted in this study. Conclusions: Many diseases have a seasonal variation and the burden of these diseases could be reduced if we device measures to detect the changes in their trend through the implementation of surveillance programs. The knowledge of the burden of these would also assist the health administrators in allocation of the resources. [Int J Res Med Sci 2016; 4(4.000: 1186-1192

  11. Seasonal Variation of Climatological Bypassing Flows around the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    LI Qiang; ZHANG Renhe

    2012-01-01

    The present study investigated diagnostically the seasonal variation of the bypassing flows caused by the splitting effect of the Tibetan Plateau (TP).The relationships among the splitting bypassing flows around the TP to precipitation in China,the westerly jet stream,and the thermal status over the TP are revealed.The bypassing flows occur from the 1st to the 22nd pentad and from the 59th to the 73rd pentad,respectively,and they disappear from the 29th to the 58th pentad.They are strongest in winter from the 1st to the 22nd pentad and from the 59th to the 73rd pentad,respectively.During the rebuilding of the bypassing flows from mid-October to mid-February,they are the main cause of precipitation over southeastern China.The enhancement of the bypassing flow intensity in March cau cause the precipitation to increase in the early stage of the persistent spring rain over southeastern China.From winter to summer,the seasonal transition of the bypassing flows in the lower troposphere precedes that of the westerly jet stream axis in the upper troposphere to the west of the TP by ~4 pentads,while from summer to winter lags by ~4 pentads.The seasonal variation of the thermal status over the TP plays an important role in the bypassing flows around the TP.The strengthening of the heating over the TP weakens the bypassing flows,and the increase in cooling over the TP is related to the rebuilding and strengthening of the bypassing flows.

  12. Influence of seasonal variations in sea level on the salinity regime of a coastal groundwater-fed wetland.

    Science.gov (United States)

    Wood, Cameron; Harrington, Glenn A

    2015-01-01

    Seasonal variations in sea level are often neglected in studies of coastal aquifers; however, they may have important controls on processes such as submarine groundwater discharge, sea water intrusion, and groundwater discharge to coastal springs and wetlands. We investigated seasonal variations in salinity in a groundwater-fed coastal wetland (the RAMSAR listed Piccaninnie Ponds in South Australia) and found that salinity peaked during winter, coincident with seasonal sea level peaks. Closer examination of salinity variations revealed a relationship between changes in sea level and changes in salinity, indicating that sea level-driven movement of the fresh water-sea water interface influences the salinity of discharging groundwater in the wetland. Moreover, the seasonal control of sea level on wetland salinity seems to override the influence of seasonal recharge. A two-dimensional variable density model helped validate this conceptual model of coastal groundwater discharge by showing that fluctuations in groundwater salinity in a coastal aquifer can be driven by a seasonal coastal boundary condition in spite of seasonal recharge/discharge dynamics. Because seasonal variations in sea level and coastal wetlands are ubiquitous throughout the world, these findings have important implications for monitoring and management of coastal groundwater-dependent ecosystems.

  13. Diversity and seasonal dynamics of airborne Archaea

    Directory of Open Access Journals (Sweden)

    J. Fröhlich-Nowoisky

    2014-05-01

    Full Text Available Archaea are widespread and abundant in many terrestrial and aquatic environments, accounting for up to ∼10% of the prokaryotes. Compared to Bacteria and other microorganisms, however, very little is known about the abundance, diversity, and dispersal of Archaea in the atmosphere. By DNA analysis targeting the 16S rRNA and amoA genes in samples of air particulate matter collected over one year at a continental sampling site in Germany, we obtained first insights into the seasonal dynamics of airborne Archaea. The detected Archaea were identified as Thaumarchaeota or Euryarchaeota, with soil Thaumarchaeota (group I.1b being present in all samples. The normalized species richness of Thaumarchaeota correlated positively with relative humidity and negatively with temperature. This together with an increase of bare agricultural soil surfaces may explain the diversity peaks observed in fall and winter. The detected Euryarchaeota were mainly methanogens with a low relative frequency of occurrence. A slight increase in their frequency during spring may be linked to fertilization processes in the surrounding agricultural fields. Comparison with samples from the Cape Verde islands and from other coastal and continental sites indicates that the proportions of Euryarchaeota are enhanced in coastal air, which is consistent with their suggested abundance in marine surface waters. We conclude that air transport may play an important role for the dispersal of Archaea, including ammonia-oxidizing Thaumarchaeota and methanogens. Also, anthropogenic activities might influence the atmospheric abundance and diversity of Archaea.

  14. Diversity and seasonal dynamics of airborne archaea

    Science.gov (United States)

    Fröhlich-Nowoisky, J.; Ruzene Nespoli, C.; Pickersgill, D. A.; Galand, P. E.; Müller-Germann, I.; Nunes, T.; Gomes Cardoso, J.; Almeida, S. M.; Pio, C.; Andreae, M. O.; Conrad, R.; Pöschl, U.; Després, V. R.

    2014-11-01

    Archaea are widespread and abundant in many terrestrial and aquatic environments, and are thus outside extreme environments, accounting for up to ~10% of the prokaryotes. Compared to bacteria and other microorganisms, however, very little is known about the abundance, diversity, and dispersal of archaea in the atmosphere. By means of DNA analysis and Sanger sequencing targeting the 16S rRNA (435 sequences) and amoA genes in samples of air particulate matter collected over 1 year at a continental sampling site in Germany, we obtained first insights into the seasonal dynamics of airborne archaea. The detected archaea were identified as Thaumarchaeota or Euryarchaeota, with soil Thaumarchaeota (group I.1b) being present in all samples. The normalized species richness of Thaumarchaeota correlated positively with relative humidity and negatively with temperature. This together with an increase in bare agricultural soil surfaces may explain the diversity peaks observed in fall and winter. The detected Euryarchaeota were mainly predicted methanogens with a low relative frequency of occurrence. A slight increase in their frequency during spring may be linked to fertilization processes in the surrounding agricultural fields. Comparison with samples from the Cape Verde islands (72 sequences) and from other coastal and continental sites indicates that the proportions of Euryarchaeota are enhanced in coastal air, which is consistent with their suggested abundance in marine surface waters. We conclude that air transport may play an important role in the dispersal of archaea, including assumed ammonia-oxidizing Thaumarchaeota and methanogens.

  15. Seasonality and comparative dynamics of six childhood infections in pre-vaccination Copenhagen

    DEFF Research Database (Denmark)

    Metcalf, C. Jessica E.; Bjørnstad, Ottar N.; Grenfell, Bryan T.;

    2009-01-01

    Seasonal variation in infection transmission is a key determinant of epidemic dynamics of acute infections. For measles, the best-understood strongly immunizing directly transmitted childhood infection, the perception is that term-time forcing is the main driver of seasonality in developed countr...... bacterial infections, pertussis, scarlet fever and diphtheria, there is additionally a strong increase in transmission during the late summer before the end of school vacations....

  16. Fitness implications of seasonal climate variation in Columbian ground squirrels.

    Science.gov (United States)

    Dobson, F Stephen; Lane, Jeffrey E; Low, Matthew; Murie, Jan O

    2016-08-01

    The influence of climate change on the fitness of wild populations is often studied in the context of the spring onset of the reproductive season. This focus is relevant for climate influences on reproductive success, but neglects other fitness-relevant periods (e.g., autumn preparation for overwintering). We examined variation in climate variables (temperature, rainfall, snowfall, and snowpack) across the full annual cycle of Columbian ground squirrels (Urocitellus columbianus) for 21 years. We investigated seasonal climate variables that were associated with fitness variables, climate variables that exhibited directional changes across the study period, and finally observed declines in fitness (-0.03 units/year; total decline = 37%) that were associated with directional changes in climate variables. Annual fitness of adult female ground squirrels was positively associated with spring temperature (r = 0.69) and early summer rainfall (r = 0.56) and negatively associated with spring snow conditions (r = -0.44 to -0.66). Across the 21 years, spring snowmelt has become significantly delayed (r = 0.48) and summer rainfall became significantly reduced (r = -0.53). Using a standardized partial regression model, we found that directional changes in the timing of spring snowmelt and early summer rainfall (i.e., progressively drier summers) had moderate influences on annual fitness, with the latter statistically significant (ρ = -0.314 and 0.437, respectively). The summer period corresponds to prehibernation fattening of young and adult ground squirrels. Had we focused on a single point in time (viz. the onset of the breeding season), we would have underestimated the influences of climate change on our population. Rather, we obtained a comprehensive understanding of the influences of climate change on individual fitness by investigating the full lifecycle.

  17. Determination and analysis of local seasonal terms of latitude variations

    Science.gov (United States)

    Soloducha, Barbara

    1991-03-01

    Local seasonal terms of latitude variations were determined on the basis of phi data of 17 BIH/IMPS stations and x, y, z data of the BIH global solution during the years 1967-1978. Some models for local corrections R to the latitude introduced by the BIH are created. The corrections R obtained from the least squares adjustment from one year data appear to be the best. The present study shows that it is necessary to determine these more frequently than once a year or to compute them for all stations simultaneously with the ERP. This will be particularly important in view of the future re-reduction of past astrometric data.

  18. ATHENS SEASONAL VARIATION OF GROUND RESISTANCE PREDICTION USING NEURAL NETWORKS

    Directory of Open Access Journals (Sweden)

    S. Anbazhagan

    2015-10-01

    Full Text Available The objective in ground resistance is to attain the most minimal ground safety esteem conceivable that bodes well monetarily and physically. An application of artificial neural networks (ANN to presage and relegation has been growing rapidly due to sundry unique characteristics of ANN models. A decent forecast is able to capture the dubiousness associated with those ground resistance. A portion of the key instabilities are soil composition, moisture content, temperature, ground electrodes and spacing of the electrodes. Propelled by this need, this paper endeavors to develop a generalized regression neural network (GRNN to predict the ground resistance. The GRNN has a single design parameter and expeditious learning and efficacious modeling for nonlinear time series. The precision of the forecast is applied to the Athens seasonal variation of ground resistance that shows the efficacy of the proposed approach.

  19. Seasonal variation of air pollution in Warsaw conurbation

    Directory of Open Access Journals (Sweden)

    Katarzyna Rozbicka

    2014-09-01

    Full Text Available Long term research shows many substances in the atmosphere are in concentration dangerous for human health and welfare and even for human life. The work presents time and spatial variation of tropospheric ozone and nitrogen dioxide concentrations. Analysis was carried out on the base of hourly values of mentioned pollutants (O3 and NO2 concentrations. Data used in the analysis comes from atmospheric monitoring stations situated in various parts of Warsaw and concerns the period 2008–2011. The influence of meteorological elements on concentration of analyzed pollutants was stated by the use of correlation and multiple regression analysis for months and seasonal periods. On this base results of statistical analysis strong correlation between tropospheric ozone, nitrogen dioxide concentration and meteorological elements is stated. In case of ozone and nitrogen dioxide the relationships with air temperature, relative humidity and solar radiation are most significant.

  20. Seasonal variation among tuberculosis suspects in four countries

    DEFF Research Database (Denmark)

    Mabaera, Biggie; Naranbat, Nymadawa; Katamba, Achilles

    2009-01-01

    The objective of the study was to analyze monthly trends across a calendar year in tuberculosis suspects and sputum smear-positive cases based on nationally representative samples of tuberculosis laboratory registers from Moldova, Mongolia, Uganda and Zimbabwe. Out of the 47 140 suspects registered...... in the tuberculosis laboratory registers, 13.4% (6312) were cases. The proportion varied from country to country, Moldova having the lowest (9%) and Uganda the highest (21%). From the monthly proportion of suspects and cases among total suspects and cases, seasonal variations were most marked in Mongolia which, among...... attendance to diagnostic laboratory services, evidenced by the contrasting findings of Mongolia (extreme continental northern climate) compared to Uganda (equatorial climate). A combination of external and possibly endogenous factors seems to determine whether tuberculosis suspects and cases present...

  1. Coronal mass ejections and geomagnetic storms: Seasonal variations

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.L.; Gosling, J.T.; McComas, D.J.

    1992-07-01

    The well-established semiannual geomagnetic cycle, with peak activity near the equinoxes, has been attributed to the angle between the solar rotation axis and the geomagnetic dipole, which modulates the GSM Bz component in the interplanetary magnetic field (MF). This effect is predicted to be accentuated in the shocked plasma ahead of fast coronal mass ejections (CMESs); its relevance to the internal fields of the ejecta is unclear. CMEs, particularly fast events driving interplanetary shocks, are the cause of almost all large geomagnetic storms near solar maximum. We use a set of CMEs identified by ISEE-3 observations of bidirectional electron streaming, plus IMF and geomagnetic data, to investigate the semiannual geomagnetic variation and its relation to CMEs. We find that the geomagnetic effectiveness of CMEs and post-shock solar wind is well-ordered by speed and by the southward component of the IMF in GSM coordinates, as well as by preexisting geomagnetic conditions. The post-shock seasonal effect, with geomagnetic effectiveness maximizing near April 5 for negative GSEQ By and near October 5 for positive GSEQ By, is identifiable in shock and shock/CME events, but not for CME events without leading shocks. When used to complement the more fundamental causal parameter of CME speed, the seasonal effect appears to have value for prediction of geomagnetic storms.

  2. Coronal mass ejections and geomagnetic storms: Seasonal variations

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.L.; Gosling, J.T.; McComas, D.J.

    1992-01-01

    The well-established semiannual geomagnetic cycle, with peak activity near the equinoxes, has been attributed to the angle between the solar rotation axis and the geomagnetic dipole, which modulates the GSM Bz component in the interplanetary magnetic field (MF). This effect is predicted to be accentuated in the shocked plasma ahead of fast coronal mass ejections (CMESs); its relevance to the internal fields of the ejecta is unclear. CMEs, particularly fast events driving interplanetary shocks, are the cause of almost all large geomagnetic storms near solar maximum. We use a set of CMEs identified by ISEE-3 observations of bidirectional electron streaming, plus IMF and geomagnetic data, to investigate the semiannual geomagnetic variation and its relation to CMEs. We find that the geomagnetic effectiveness of CMEs and post-shock solar wind is well-ordered by speed and by the southward component of the IMF in GSM coordinates, as well as by preexisting geomagnetic conditions. The post-shock seasonal effect, with geomagnetic effectiveness maximizing near April 5 for negative GSEQ By and near October 5 for positive GSEQ By, is identifiable in shock and shock/CME events, but not for CME events without leading shocks. When used to complement the more fundamental causal parameter of CME speed, the seasonal effect appears to have value for prediction of geomagnetic storms.

  3. Seasonal variation of the South Indian tropical gyre

    Science.gov (United States)

    Aguiar-González, Borja; Ponsoni, Leandro; Ridderinkhof, Herman; van Aken, Hendrik M.; de Ruijter, Will P. M.; Maas, Leo R. M.

    2016-04-01

    The South Indian tropical gyre receives and redistributes water masses from the Indonesian Throughflow (ITF), a source of Pacific Ocean water which represents the only low-latitude connector between the world oceans and, therefore, a key component in the global ocean circulation and climate system. We investigate the seasonal variation of the South Indian tropical gyre and its associated open-ocean upwelling system, known as the Seychelles-Chagos Thermocline Ridge (SCTR), based on satellite altimeter data (AVISO) and global atlases of temperature and salinity (CARS09), wind stress (SCOW) and wind-driven circulation. Two novel large-scale features governing the upper geostrophic circulation of the South Indian tropical gyre are revealed. First, the seasonal shrinkage of the ocean gyre. This occurs when the South Equatorial Countercurrent (SECC) recirculates before arrival to Sumatra from winter to spring, in apparent synchronization with the annual cycle of the ITF. Second, the open-ocean upwelling is found to vary following seasonality of the overlying geostrophic ocean gyre, a relationship that has not been previously shown for this region. An analysis of major forcing mechanisms suggests that the thermocline ridge results from the constructive interaction of basin-scale wind stress curl, local-scale wind stress forcing and remote forcing driven by Rossby waves of different periodicity: semiannual in the west, under the strong influence of monsoonal winds; and, annual in the east, where the southeasterlies prevail. One exception occurs during winter, when the well-known westward intensification of the upwelling core, the Seychelles Dome, is shown to be largely a response of the wind-driven circulation. Broadly speaking, the seasonal shrinkage of the ocean gyre (and the SCTR) is the one feature that differs most when the geostrophic circulation is compared to the wind-driven Sverdrup circulation. From late autumn to spring, the eastward SECC recirculates early in

  4. Seasonal variations of decay rate measurement data and their interpretation.

    Science.gov (United States)

    Schrader, Heinrich

    2016-08-01

    Measurement data of long-lived radionuclides, for example, (85)Kr, (90)Sr, (108m)Ag, (133)Ba, (152)Eu, (154)Eu and (226)Ra, and particularly the relative residuals of fitted raw data from current measurements of ionization chambers for half-life determination show small periodic seasonal variations with amplitudes of about 0.15%. The interpretation of these fluctuations is a matter of controversy whether the observed effect is produced by some interaction with the radionuclides themselves or is an artifact of the measuring chain. At the origin of such a discussion there is the exponential decay law of radioactive substances used for data fitting, one of the fundamentals of nuclear physics. Some groups of physicists use statistical methods and analyze correlations with various parameters of the measurement data and, for example, the Earth-Sun distance, as a basis of interpretation. In this article, data measured at the Physikalisch-Technische Bundesanstalt and published earlier are the subject of a correlation analysis using the corresponding time series of data with varying measurement conditions. An overview of these measurement conditions producing instrument instabilities is given and causality relations are discussed. The resulting correlation coefficients for various series of the same radionuclide using similar measurement conditions are in the order of 0.7, which indicates a high correlation, and for series of the same radionuclide using different measurement conditions and changes of the measuring chain of the order of -0.2 or even lower, which indicates an anti-correlation. These results provide strong arguments that the observed seasonal variations are caused by the measuring chain and, in particular, by the type of measuring electronics used.

  5. Density-mediated carry-over effects explain variation in breeding output across time in a seasonal population.

    Science.gov (United States)

    Betini, Gustavo S; Griswold, Cortland K; Norris, D Ryan

    2013-10-23

    In seasonal environments, where density dependence can operate throughout the annual cycle, vital rates are typically considered to be a function of the number of individuals at the beginning of each season. However, variation in density in the previous season could also cause surviving individuals to be in poor physiological condition, which could carry over to influence individual success in the following season. We examine this hypothesis using replicated populations of Drosophila melanogaster, the common fruitfly, over 23 non-overlapping generations with distinct breeding and non-breeding seasons. We found that the density at the beginning of the non-breeding season negatively affected the fresh weight of individuals that survived the non-breeding season and resulted in a 25% decrease in per capita breeding output among those that survived to the next season to breed. At the population level, per capita breeding output was best explained by a model that incorporated density at the beginning of the previous non-breeding season (carry-over effect, COE) and density at the beginning of the breeding season. Our results support the idea that density-mediated COEs are critical for understanding population dynamics in seasonal environments.

  6. Incorporating Temperature-driven Seasonal Variation in Survival, Growth, and Reproduction Models for Small Fish

    Science.gov (United States)

    Seasonal variation in survival and reproduction can be a large source of prediction uncertainty in models used for conservation and management. A seasonally varying matrix population model is developed that incorporates temperature-driven differences in mortality and reproduction...

  7. Modelling Seasonal Carbon Dynamics on Fen Peatlands

    Science.gov (United States)

    Giebels, Michael; Beyer, Madlen; Augustin, Jürgen; Roppel, Mario; Juszczak, Radoszlav; Serba, Tomasz

    2010-05-01

    In Germany more than 99 % of fens have lost their carbon and nutrient sink function due to heavy drainage and agricultural land use especially during the last decades and thus resulted in compression and heavy peat loss (CHARMAN 2002; JOOSTEN & CLARKE 2002; SUCCOW & JOOSTEN 2001; AUGUSTIN et al. 1996; KUNTZE 1993). Therefore fen peatlands play an important part (4-5 %) in the national anthropogenic trace gas budget. But only a small part of drained and agricultural used fens in NE Germany can be restored. Knowledge of the influence of land use to trace gas exchange is important for mitigation of the climate impact of the anthropogenic peatland use. We study carbon exchanges between soil and atmosphere on several fen peatland use areas at different sites in NE-Germany. Our research covers peatlands of supposed strongly climate forcing land use (cornfield and intensive pasture) and of probably less forcing, alternative types (meadow and extensive pasture) as well as rewetted (formerly drained) areas and near-natural sites like a low-degraded fen and a wetted alder woodland. We measured trace gas fluxes with manual and automatic chambers in periodic routines since spring 2007. The used chamber technique bases on DROESLER (2005). In total we now do research at 22 sites situated in 5 different locations covering agricultural, varying states of rewetted and near-natural treatments. We present results of at least 2 years of measurements on our site of varying types of agricultural land use. There we found significant differences in the annual carbon balances depending on the genesis of the observed sites and the seasonal dynamics. Annual balances were constructed by applying single respiration and photosynthesis CO2 models for each measurement campaign. These models were based on LLOYD-TAYLOR (1994) and Michaelis-Menten-Kinetics respectively. Crosswise comparison of different site treatments combined with the seasonal environmental observations give good hints for the

  8. Seasonal variation in the mating system of a selfing annual with large floral displays

    Science.gov (United States)

    Yin, Ge; Barrett, Spencer C. H.; Luo, Yi-Bo; Bai, Wei-Ning

    2016-01-01

    Background and Aims Flowering plants display considerable variation in mating system, specifically the relative frequency of cross- and self-fertilization. The majority of estimates of outcrossing rate do not account for temporal variation, particularly during the flowering season. Here, we investigated seasonal variation in mating and fertility in Incarvillea sinensis (Bignoniaceae), an annual with showy, insect-pollinated, ‘one-day’ flowers capable of delayed selfing. We examined the influence of several biotic and abiotic environmental factors on day-to-day variation in fruit set, seed set and patterns of mating. Methods We recorded daily flower number and pollinator abundance in nine 3 × 3-m patches in a population at Mu Us Sand land, Inner Mongolia, China. From marked flowers we collected data on daily fruit and seed set and estimated outcrossing rate and biparental inbreeding using six microsatellite loci and 172 open-pollinated families throughout the flowering period. Key Results Flower density increased significantly over most of the 50-d flowering season, but was associated with a decline in levels of pollinator service by bees, particularly on windy days. Fruit and seed set declined over time, especially during the latter third of the flowering period. Multilocus estimates of outcrossing rate were obtained using two methods (the programs MLTR and BORICE) and both indicated high selfing rates of ∼80 %. There was evidence for a significant increase in levels of selfing as the flowering season progressed and pollinator visitation declined. Biparental inbreeding also declined significantly as the flowering season progressed. Conclusions Temporal variation in outcrossing rates may be a common feature of the mating biology of annual, insect-pollinated plants of harsh environments but our study is the first to examine seasonal mating-system dynamics in this context. Despite having large flowers and showy floral displays, I. sinensis attracted

  9. Seasonal Variation in Mortality, Medical Care Expenditure and Institutionalization in Older People

    DEFF Research Database (Denmark)

    Rolden, Herbert Jan Albert; Rohling, Jos Hermanus Theodoor; van Bodegom, David

    2015-01-01

    BACKGROUND: The mortality rates of older people changes with the seasons. However, it has not been properly investigated whether the seasons affect medical care expenditure (MCE) and institutionalization. Seasonal variation in MCE is plausible, as MCE rises exponentially before death. It is there......BACKGROUND: The mortality rates of older people changes with the seasons. However, it has not been properly investigated whether the seasons affect medical care expenditure (MCE) and institutionalization. Seasonal variation in MCE is plausible, as MCE rises exponentially before death...

  10. Asynchrony of seasons: genetic differentiation associated with geographic variation in climatic seasonality and reproductive phenology.

    Science.gov (United States)

    Quintero, Ignacio; González-Caro, Sebastián; Zalamea, Paul-Camilo; Cadena, Carlos Daniel

    2014-09-01

    Many organisms exhibit distinct breeding seasons tracking food availability. If conspecific populations inhabit areas that experience different temporal cycles in food availability spurred by variation in precipitation regimes, then they should display asynchronous breeding seasons. Thus, such populations might exhibit a temporal barrier to gene flow, which may potentially promote genetic differentiation. We test a central prediction of this hypothesis, namely, that individuals living in areas with more asynchronous precipitation regimes should be more genetically differentiated than individuals living in areas with more similar precipitation regimes. Using mitochondrial DNA sequences, climatic data, and geographical/ecological distances between individuals of 57 New World bird species mostly from the tropics, we examined the effect of asynchronous precipitation (a proxy for asynchronous resource availability) on genetic differentiation. We found evidence for a positive and significant cross-species effect of precipitation asynchrony on genetic distance after accounting for geographical/ecological distances, suggesting that current climatic conditions may play a role in population differentiation. Spatial asynchrony in climate may thus drive evolutionary divergence in the absence of overt geographic barriers to gene flow; this mechanism contrasts with those invoked by most models of biotic diversification emphasizing physical or ecological changes to the landscape as drivers of divergence.

  11. Seasonal Variation of Eutrophication in Some Lakes of Danube Delta Biosphere Reserve.

    Science.gov (United States)

    Török, Liliana; Török, Zsolt; Carstea, Elfrida M; Savastru, Dan

    2017-01-01

      To understand the trophic state of lakes, this study aims to determine the dynamics of phytoplankton assemblages and the main factors that influence their seasonal variation. Sampling campaigns were carried out in three lakes from the Danube Delta Biosphere Reserve. Spectral analysis of specific phytoplankton pigments was applied as a diagnostic marker to establish the distribution and composition of phytoplankton taxonomic groups. Fluorescence spectroscopy was used to quantify changes in dissolved organic matter (DOM). The relative contribution of the main phytoplankton groups to the total phytoplankton biomass and the trend of development during succession of the seasons showed that cyanobacteria could raise potential ecological or human health problems. Moreover, fluorescence spectroscopy revealed that Cryptophyta and cyanobacteria were the main contributors to the protein-like components of DOM. It was concluded that fluorescence could be used to provide a qualitative evaluation of the eutrophication degree in Danube Delta lakes.

  12. Seasonal flow speed variations of marine-terminating outlet glaciers in northwestern Greenland

    Science.gov (United States)

    Sakakibara, Daiki; Sugiyama, Shin

    2017-04-01

    The Greenland ice sheet is losing mass under the influence of increases in surface melting and ice discharge from marine-terminating outlet glaciers. To project changes of the ice sheet under the changing climate, better understanding of the dynamics of marine-terminating outlet glaciers is required. To this end, we studied seasonal flow speed variations of 10 marine-terminating outlet glaciers along the coast of the Prudhoe Land, northwestern Greenland. Surface speed near the glacier front was measured using Landsat 8 images taken from 2014 to 2016. We obtained 18-28 speed data for each month from March to September. Area covered by supraglacial ponds and meltwater plume in front of the glacier were mapped by analyzing the Landsat images. Flow speed variations were compared with the ice front positions, sea ice condition near the termini, air temperature, area of supraglacial ponds and meltwater plume to investigate the driver of the seasonal changes in the ice dynamics. All of the study glaciers accelerated from May/June to June/July, and then slowed down from July to September. Magnitude of the speedups ranged between 120 and 680 m a-1. In early summer, flow speed increased as air temperature rose up and the area of supraglacial ponds expanded. These observations suggest that the seasonal speedup was caused by meltwater input to the glacier bed. Flow speed dropped when annual sum of the positive-degree day reached 100 K d, supraglacial water drained and meltwater plume appeared. These changes occurred before air temperature reached the summer maximum. Our interpretation of the glacier deceleration is that subglacial drainage system had developed because of the drainage of supraglacial ponds which lead to the drop in the subglacial water pressure. Our study demonstrated that the rate of meltwater production controls the seasonal acceleration, and the drainage of supraglacial ponds triggers the later deceleration.

  13. Nonbreeding-Season Drivers of Population Dynamics in Seasonal Migrants: Conservation Parallels Across Taxa

    Directory of Open Access Journals (Sweden)

    Anna M. Calvert

    2009-12-01

    Full Text Available For seasonal migrants, logistical constraints have often limited conservation efforts to improving survival and reproduction during the breeding season only. Yet, mounting empirical evidence suggests that events occurring throughout the migratory life cycle can critically alter the demography of many migrant species. Herein, we build upon recent syntheses of avian migration research to review the role of non-breeding seasons in determining the population dynamics and fitness of diverse migratory taxa, including salmonid fishes, marine mammals, ungulates, sea turtles, butterflies, and numerous bird groups. We discuss several similarities across these varied migrants: (i non-breeding survivorship tends to be a strong driver of population growth; (ii non-breeding events can affect fitness in subsequent seasons through seasonal interactions at individual- and population-levels; (iii broad-scale climatic influences often alter non-breeding resources and migration timing, and may amplify population impacts through covariation among seasonal vital rates; and (iv changes to both stationary and migratory non-breeding habitats can have important consequences for abundance and population trends. Finally, we draw on these patterns to recommend that future conservation research for seasonal migrants will benefit from: (1 more explicit recognition of the important parallels among taxonomically diverse migratory animals; (2 an expanded research perspective focused on quantification of all seasonal vital rates and their interactions; and (3 the development of detailed population projection models that account for complexity and uncertainty in migrant population dynamics.

  14. Seasonal dynamic thinning at Helheim Glacier

    DEFF Research Database (Denmark)

    Bevan, Suzanne L.; Luckman, Adrian; Khan, Shfaqat Abbas

    2015-01-01

    We investigate three annual mass-balance cycles on Helheim Glacier in south-east Greenland using TanDEM-X interferometric digital elevation models (DEMs), bedrock GPS measurements, and ice velocity from feature-tracking. The DEMs exhibit seasonal surface elevation cycles at elevations up to 800 m...

  15. Spatial and seasonal variations in evapotranspiration over Canada's landmass

    Directory of Open Access Journals (Sweden)

    S. Wang

    2013-05-01

    Full Text Available A 30 yr (1979–2008 dataset of actual evapotranspiration (ET at 1 km resolution was generated over Canada's landmass by integrating remote sensing land surface data and gridded climate data using the EALCO model run at 30 min time step. This long-term high resolution dataset was used to characterize the spatiotemporal variations in ET across Canada. The results show that annual ET varied from 600 mm yr−1 over several regions in the south to less than 100 mm yr−1 in the northern arctic. Nationally, ET in summer (i.e., June to August comprised 65% of the annual total amount. ET in the cold season remained mostly below 10 mm month−1 over the country. Negative monthly ET was obtained over the arctic region in winter, indicating EALCO simulated a larger amount of condensation than ET. Overall, the mean ET over the entire Canadian landmass for the 30 yr was 239 mm yr−1, or 44% of its corresponding precipitation. Comparisons of available ET studies in Canada revealed large uncertainties in ET estimates associated with using different approaches. The scarcity of ET measurements for the diverse ecosystems in Canada remains a significant challenge for reducing the uncertainties; this gap needs to be addressed in future studies to improve capabilities in climate/weather modelling and water resource management.

  16. Seasonal variations of injury and overtraining in elite athletes.

    Science.gov (United States)

    Koutedakis, Y; Sharp, N C

    1998-01-01

    To assess reported injuries and cases of overtraining in relation to training and competition cycles, aerobic versus anaerobic sport, and gender. A total of 163 elite male and 94 elite female athletes from eight different sports volunteered. They reported 212 musculoskeletal injuries and 38 cases of the overtraining syndrome. These injuries and cases of overtraining were then arranged according to the training or competition cycle in which they occurred, whether the sufferers were male or female athletes, and the metabolic characteristics of the sports in which the injuries and overtraining occurred. The preparation (October to February), precompetition (March to May), and competition (June to August) cycles were associated with 9%, 19%, and 32% of the injuries reported by the men, respectively, and with 8%, 10%, and 22% of the injuries reported by the women, respectively. For the same cycles, cases of overtraining were found to be 15%, 24%, and 35% for the men, respectively, and 4%, 7%, and 15% for the women, respectively. For both men and women, the competition cycle produced significantly more injuries and incidents of overtraining than the preparation and precompetition cycles (p injuries (p injuries during the precompetition (p overtraining during the competition cycle (p injuries and overtraining occurred. Elite athletes are more likely to become injured or overtrained during the precompetition and, especially, competition cycles than in the preparation cycle. Parallel seasonal variations were also found when data were analyzed for aerobic versus anaerobic sport and gender.

  17. Allergenic pollen season variations in the past two decades under changing climate in the United States.

    Science.gov (United States)

    Zhang, Yong; Bielory, Leonard; Mi, Zhongyuan; Cai, Ting; Robock, Alan; Georgopoulos, Panos

    2015-04-01

    Many diseases are linked with climate trends and variations. In particular, climate change is expected to alter the spatiotemporal dynamics of allergenic airborne pollen and potentially increase occurrence of allergic airway disease. Understanding the spatiotemporal patterns of changes in pollen season timing and levels is thus important in assessing climate impacts on aerobiology and allergy caused by allergenic airborne pollen. Here, we describe the spatiotemporal patterns of changes in the seasonal timing and levels of allergenic airborne pollen for multiple taxa in different climate regions at a continental scale. The allergenic pollen seasons of representative trees, weeds and grass during the past decade (2001-2010) across the contiguous United States have been observed to start 3.0 [95% Confidence Interval (CI), 1.1-4.9] days earlier on average than in the 1990s (1994-2000). The average peak value and annual total of daily counted airborne pollen have increased by 42.4% (95% CI, 21.9-62.9%) and 46.0% (95% CI, 21.5-70.5%), respectively. Changes of pollen season timing and airborne levels depend on latitude, and are associated with changes of growing degree days, frost free days, and precipitation. These changes are likely due to recent climate change and particularly the enhanced warming and precipitation at higher latitudes in the contiguous United States.

  18. Disentangling seasonal bacterioplankton population dynamics by high-frequency sampling.

    Science.gov (United States)

    Lindh, Markus V; Sjöstedt, Johanna; Andersson, Anders F; Baltar, Federico; Hugerth, Luisa W; Lundin, Daniel; Muthusamy, Saraladevi; Legrand, Catherine; Pinhassi, Jarone

    2015-07-01

    Multiyear comparisons of bacterioplankton succession reveal that environmental conditions drive community shifts with repeatable patterns between years. However, corresponding insight into bacterioplankton dynamics at a temporal resolution relevant for detailed examination of variation and characteristics of specific populations within years is essentially lacking. During 1 year, we collected 46 samples in the Baltic Sea for assessing bacterial community composition by 16S rRNA gene pyrosequencing (nearly twice weekly during productive season). Beta-diversity analysis showed distinct clustering of samples, attributable to seemingly synchronous temporal transitions among populations (populations defined by 97% 16S rRNA gene sequence identity). A wide spectrum of bacterioplankton dynamics was evident, where divergent temporal patterns resulted both from pronounced differences in relative abundance and presence/absence of populations. Rates of change in relative abundance calculated for individual populations ranged from 0.23 to 1.79 day(-1) . Populations that were persistently dominant, transiently abundant or generally rare were found in several major bacterial groups, implying evolution has favoured a similar variety of life strategies within these groups. These findings suggest that high temporal resolution sampling allows constraining the timescales and frequencies at which distinct populations transition between being abundant or rare, thus potentially providing clues about physical, chemical or biological forcing on bacterioplankton community structure.

  19. Seasonal variations of cauda epididymal spermatozoa of bucks

    Directory of Open Access Journals (Sweden)

    Dilip Kumar Swain

    2016-09-01

    Full Text Available Objective: The study was conducted to evaluate the influence of season on cauda epididymal spermatozoa isolated from bucks. Materials and methods: Testes of 30 mature bucks were collected from local slaughter house, and were processed for the retrieval of cauda epididymal spermatozoa for evaluation. Testes were collected in three seasons (winter, summer and rainy, and each season was having 10 pairs of testicles. Recovered spermatozoa from the cauda epididymis were processed immediately for evaluation of semen attributes (Spermatozoa motility, viability, plasma membrane integrity, acrosomal status and DNA integrity. Results: Physiological effect of season was observed on progressive motility, percent of live spermatozoa, spermatozoal membrane integrity (HOST, acrosomal integrity, capacitation status and DNA integrity. Progressive motility, percent live spermatozoa, HOST positive spermatozoa, were found significantly (P<0.05 high in summer season, whereas, significantly (P<0.05 lower comet positive spermatozoa were found in summer season as compared to rainy and winter. Compromised acrosomal status was seen in winter and rainy seasons as compared to summer. Conclusion: Compromised acrosome along with plasma membrane and higher percentage of spermatozoa with damaged DNA in cauda spermatozoa were observed during winter and rainy seasons as compared to summer season. Summer season was found to be the most suitable season for collection of cauda epididymal spermatozoa and can effectively be used for assisted reproduction with further investigations of associated mechanisms. [J Adv Vet Anim Res 2016; 3(3.000: 263-267

  20. Seasonal variation in child mortality in rural Guinea-Bissau.

    Science.gov (United States)

    Nielsen, Bibi Uhre; Byberg, Stine; Aaby, Peter; Rodrigues, Amabelia; Benn, Christine Stabell; Fisker, Ane Baerent

    2017-07-01

    In many African countries, child mortality is higher in the rainy season than in the dry season. We investigated the effect of season on child mortality by time periods, sex and age in rural Guinea-Bissau. Bandim health project follows children under-five in a health and demographic surveillance system in rural Guinea-Bissau. We compared the mortality in the rainy season (June to November) between 1990 and 2013 with the mortality in the dry season (December to May) in Cox proportional hazards models providing rainy vs. dry season mortality rate ratios (r/d-mrr). Seasonal effects were estimated in strata defined by time periods with different frequency of vaccination campaigns, sex and age (<1 month, 1-11 months, 12-59 months). Verbal autopsies were interpreted using InterVa-4 software. From 1990 to 2013, overall mortality was declined by almost two-thirds among 81 292 children (10 588 deaths). Mortality was 51% (95% ci: 45-58%) higher in the rainy season than in the dry season throughout the study period. The seasonal difference increased significantly with age, the r/d-mrr being 0.94 (0.86-1.03) among neonates, 1.57 (1.46-1.69) in post-neonatal infants and 1.83 (1.72-1.95) in under-five children (P for same effect <0.001). According to the InterVa, malaria deaths were the main reason for the seasonal mortality difference, causing 50% of all deaths in the rainy season, but only if the InterVa included season of death, making the argument self-confirmatory. The mortality declined throughout the study, yet rainy season continued to be associated with 51% higher overall mortality. © 2017 The Authors. Tropical Medicine & International Health Published by John Wiley & Sons Ltd.

  1. Seasonal variation in soil nitrogen availability across a fertilization chronosequence in moist acidic tundra

    Science.gov (United States)

    McLaren, J. R.; Gough, L.; Weintraub, M. N.

    2012-12-01

    Changes in global climate may result in altered timing of seasonal events including the timing of the spring-thaw and fall freeze-up. In addition to this changing seasonality, arctic environments are experiencing overall increases in nutrient availability caused by climate warming resulting in alterations of plant species composition, such as the observed increases in the abundance of deciduous shrubs. Changing species composition may have large effects on nutrient dynamics in the surrounding ecosystem because of documented differences in how particular plant species influence soil nutrient availability. Although we have some idea of how plant identity influences soil nutrients, soil biogeochemical processes are strongly seasonal, and we have a poor understanding of how plant identity, or nutrient levels, may influence these seasonal patterns. We examined the responses of moist acidic tundra to experimentally increased soil nutrient availability and the accompanying increase in shrub abundance at the Arctic Long Term Ecological Research (LTER) site at Toolik Lake, Alaska. We examined a chrono-sequence of long-term fertilization experiments, composed of experiments fertilized for 5, 15 and 22 years, which has resulted in increasing shrub density with time since fertilization. The fertilized plots receive both nitrogen (N, 10 g/m2/yr) and phosphorus (5 g/m2/yr) annually following snowmelt. In the 2011 growing season we measured variation in soil available N weekly, including measures of ammonium (NH4), nitrate (NO3) and total free amino acids (TFAA). We found that differences between fertilized and control plots depended strongly on both the seasonal timing of measurements, as well as the duration of the fertilization treatment. Early in the growing season fertilization resulted in large increases in available soil N (both NH4 and NO3) across the entire chronosequence. As the season progressed, however, older fertilized plots show evidence of N saturation, where

  2. Estimates of eddy turbulence consistent with seasonal variations of atomic oxygen and its possible role in the seasonal cycle of mesopause temperature

    Directory of Open Access Journals (Sweden)

    M. N. Vlasov

    2010-11-01

    Full Text Available According to current understanding, adiabatic cooling and heating induced by the meridional circulation driven by gravity waves is the major process for the cold summer and warm winter polar upper mesosphere. However, our calculations show that the upward/downward motion needed for adiabatic cooling/heating of the summer/winter polar mesopause simultaneously induces a seasonal variation in both the O maximum density and the altitude of the [O] peak that is opposite to the observed variables generalized by the MSISE-90 model. It is usually accepted that eddy turbulence can produce the [O] seasonal variations. Using this approach, we can infer the eddy diffusion coefficient for the different seasons. Taking these results and experimental data on the eddy diffusion coefficient, we consider in detail and estimate the heating and cooling caused by eddy turbulence in the summer and winter polar upper mesosphere. The seasonal variations of these processes are similar to the seasonal variations of the temperature and mesopause. These results lead to the conclusion that heating/cooling by eddy turbulence is an important component in the energy budget and that adiabatic cooling/heating induced by upward/downward motion cannot dominate in the mesopause region. Our study shows that the impact of the dynamic process, induced by gravity waves, on [O] distributions must be included in models of thermal balance in the upper mesosphere and lower thermosphere (MLT for a consistent description because (a the [O] distribution is very sensitive to dynamic processes, and (b atomic oxygen plays a very important role in chemical heating and infrared cooling in the MLT. To our knowledge, this is the first attempt to consider this aspect of the problem.

  3. Genetic and phenotypically flexible components of seasonal variation in immune function

    NARCIS (Netherlands)

    Versteegh, M. A.; Helm, B.; Kleynhans, E. J.; Gwinner, E.; Tieleman, B. I.

    2014-01-01

    Animals cope with seasonal variation in environmental factors by adjustments of physiology and life history. When seasonal variation is partly predictable, such adjustments can be based on a genetic component or be phenotypically flexible. Animals have to allocate limited resources over different de

  4. Seasonal variation in child mortality in rural Guinea-Bissau

    DEFF Research Database (Denmark)

    Nielsen, Bibi Uhre; Byberg, Stine; Aaby, Peter

    2017-01-01

    81 292 children (10 588 deaths). Mortality was 51% (95% ci: 45-58%) higher in the rainy season than in the dry season throughout the study period. The seasonal difference increased significantly with age, the r/d-mrr being 0.94 (0.86-1.03) among neonates, 1.57 (1.46-1.69) in post-neonatal infants...... and 1.83 (1.72-1.95) in under-five children (P for same effect deaths were the main reason for the seasonal mortality difference, causing 50% of all deaths in the rainy season, but only if the InterVa included season of death, making the argument self...

  5. Climate variation drives dengue dynamics

    Science.gov (United States)

    Xu, Lei; Stige, Leif C.; Chan, Kung-Sik; Zhou, Jie; Yang, Jun; Sang, Shaowei; Wang, Ming; Yang, Zhicong; Yan, Ziqiang; Jiang, Tong; Lu, Liang; Yue, Yujuan; Liu, Xiaobo; Lin, Hualiang; Xu, Jianguo; Liu, Qiyong; Stenseth, Nils Chr.

    2017-01-01

    Dengue, a viral infection transmitted between people by mosquitoes, is one of the most rapidly spreading diseases in the world. Here, we report the analyses covering 11 y (2005–2015) from the city of Guangzhou in southern China. Using the first 8 y of data to develop an ecologically based model for the dengue system, we reliably predict the following 3 y of dengue dynamics—years with exceptionally extensive dengue outbreaks. We demonstrate that climate conditions, through the effects of rainfall and temperature on mosquito abundance and dengue transmission rate, play key roles in explaining the temporal dynamics of dengue incidence in the human population. Our study thus contributes to a better understanding of dengue dynamics and provides a predictive tool for preventive dengue reduction strategies. PMID:27940911

  6. Observations of, and sources of the spatial and temporal variability of ozone in the middle atmosphere on climatological time scales (OZMAP) and equatorial dynamics: Seasonal variations of ozone trends

    Science.gov (United States)

    Entzian, G.; Grasnick, K. H.; Taubenheim, J.

    1989-01-01

    The long term trends (least square linear regression with time) of ozone content at seven European, seven North American, three Japanese and two tropical stations during 21 years (1964 to 1984) are analyzed. In all regions negative trends are observed during the 1970s, but are partly compensated by limited periods of positive trends during the late 1960s and late 1970s. Solely the North American ozone data show negative trends in all 10 year periods. When the long term ozone trends are evaluated for each month of the year separately, a seasonal variation is revealed, which in Europe and North America has largest negative trends in late winter and spring. While in Europe the negative trends in winter/spring are partly compensated by positive trends in summer, in North America the summer values reach only zero, retaining the significant negative trend in annual mean values. In contrast to the antarctic ozone hole, the spring reduction of ozone in Europe and in North America is associated with stratospheric temperatures increasing in the analyzed period and therefore is consistent with the major natural ozone production and loss processes.

  7. Seasonal Variation on Microbial Community and Methane Production during Anaerobic Digestion of Cattle Manure in Brazil.

    Science.gov (United States)

    Resende, Juliana Alves; Godon, Jean-Jacques; Bonnafous, Anaïs; Arcuri, Pedro Braga; Silva, Vânia Lúcia; Otenio, Marcelo Henrique; Diniz, Cláudio Galuppo

    2016-04-01

    Anaerobic digestion is an alternative method for the treatment of animal manure and wastewater. The anaerobic bioconversion of biomass requires a multi-step biological process, including microorganisms with distinct roles. The diversity and composition of microbial structure in pilot-scale anaerobic digestion operating at ambient temperature in Brazil were studied. Influence of the seasonal and temporal patterns on bacterial and archaeal communities were assessed by studying the variations in density, dynamic and diversity and structure. The average daily biogas produced in the summer and winter months was 18.7 and 16 L day(-1), respectively, and there was no difference in the average methane yield. Quantitative PCR analysis revealed that no differences in abundances and dynamics were found for bacterial communities and the total number of Archaea in different seasons. Analysis of bacterial clone libraries revealed a predominance of Firmicutes (54.5 %/summer and 46.7 %/winter) and Bacteroidetes (31.4 %/summer and 44.4 %/winter). Within the Archaea, the phylum Euryarchaeota was predominant in both digesters. Phylogenetic distribution showed changes in percentage between the phyla identified, but no alterations were recorded in the quality and amount of produced methane or community dynamics. The results may suggest that redundancy of microbial groups may have occurred, pointing to a more complex microbial community in the ecosystem related to this ambient temperature system.

  8. Seasonal variation in microhabitat of salamanders: environmental variation or shift of habitat selection?

    Directory of Open Access Journals (Sweden)

    Enrico Lunghi

    2015-08-01

    Full Text Available Relationships between species and their habitats are not always constant. Different processes may determine changes in species-habitat association: individuals may prefer different habitat typologies in different periods, or they may be forced to occupy a different habitat in order to follow the changing environment. The aim of our study was to assess whether cave salamanders change their habitat association pattern through the year, and to test whether such changes are determined by environmental changes or by changes in preferences. We monitored multiple caves in Central Italy through one year, and monthly measured biotic and abiotic features of microhabitat and recorded Italian cave salamanders distribution. We used mixed models and niche similarity tests to assess whether species-habitat relationships remain constant through the year. Microhabitat showed strong seasonal variation, with the highest variability in the superficial sectors. Salamanders were associated to relatively cold and humid sectors in summer, but not during winter. Such apparent shift in habitat preferences mostly occurred because the environmental gradient changed through the year, while individuals generally selected similar conditions. Nevertheless, juveniles were more tolerant to dry sectors during late winter, when food demand was highest. This suggests that tolerance for suboptimal abiotic conditions may change through time, depending on the required resources. Differences in habitat use are jointly determined by environmental variation through time, and by changes in the preferred habitat. The trade-offs between tolerance and resources requirement are major determinant of such variation.

  9. Seasonal variation of imipramine binding in the blood platelets of normal controls and depressed patients

    Energy Technology Data Exchange (ETDEWEB)

    Arora, R.C.; Meltzer, H.Y.

    1988-02-01

    Imipramine binding (IB) was studied in the blood platelets from normal controls and depressed patients over a 4-year period (1981-1984) to determine if seasonal variation was present in Bmax or KD. Bimonthly variation in the Bmax of IB was found in normal controls studied longitudinally. No such variation was found when individual values from normal controls were examined on a monthly or seasonal basis. Bmax in depressed patients showed a significant seasonal, but not monthly, variation. KD of IB varied in normal controls using monthly or seasonal data, but not in the probably more reliable bimonthly data. These results suggest that IB studies comparing groups of subjects should match groups for season of the year or, for greater accuracy, month of the year.

  10. Modeled Seasonal Variations of Firn Density Induced by Steady State Surface Air Temperature Cycle

    Science.gov (United States)

    Jun, Li; Zwally, H. Jay; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    Seasonal variations of firn density in ice-sheet firn layers have been attributed to variations in deposition processes or other processes within the upper firn. A recent high-resolution (mm scale) density profile, measured along a 181 m core from Antarctica, showed small-scale density variations with a clear seasonal cycle that apparently was not-related to seasonal variations in deposition or known near-surface processes (Gerland and others 1999). A recent model of surface elevation changes (Zwally and Li, submitted) produced a seasonal variation in firn densification, and explained the seasonal surface elevation changes observed by satellite radar altimeters. In this study, we apply our 1-D time-dependent numerical model of firn densification that includes a temperature-dependent formulation of firn densification based on laboratory measurements of grain growth. The model is driven by a steady-state seasonal surface temperature and a constant accumulation rate appropriate for the measured Antarctic ice core. The modeled seasonal variations in firn density show that the layers of snow deposited during spring to mid-summer with the highest temperature history compress to the highest density, and the layers deposited during later summer to autumn with the lowest temperature history compress to the lowest density. The initial amplitude of the seasonal difference of about 0.13 reduces to about 0.09 in five years and asymptotically to 0.92 at depth, which is consistent with the core measurements.

  11. Seasonal variation in diurnal atmospheric grass pollen concentration profiles

    DEFF Research Database (Denmark)

    Peel, Robert George; Ørby, Pia Viuf; Skjøth, Carsten Ambelas

    2014-01-01

    In this study, the diurnal atmospheric grass pollen concentration profile within the Danish city of Aarhus was shown to change in a systematic manner as the pollen season progressed. Although diurnal grass pollen profiles can differ greatly from day-to-day, it is common practice to establish...... the time of day when peak concentrations are most likely to occur using seasonally averaged diurnal profiles. Atmospheric pollen loads are highly dependent upon emissions, and different species of grass are known to flower and emit pollen at different times of the day and during different periods...... of the pollen season. Pollen concentrations are also influenced by meteorological factors - directly through those parameters that govern pollen dispersion and transport, and indirectly through the weather-driven flowering process. We found that three different profiles dominated the grass pollen season...

  12. Seasonal dynamics of water use efficiency of typical forest and grassland ecosystems in China

    CERN Document Server

    Zhu, Xianjin; Wang, Qiufeng; Hu, Zhongmin; Han, Shijie; Yan, Junhua; Wang, Yanfen; Zhao, Liang

    2014-01-01

    We selected four sites of ChinaFLUX representing four major ecosystem types in China-Changbaishan temperate broad-leaved Korean pine mixed forest (CBS), Dinghushan subtropical evergreen broadleaved forest (DHS), Inner Mongolia temperate steppe (NM), and Haibei alpine shrub-meadow (HBGC)-to study the seasonal dynamics of ecosystem water use efficiency (WUE = GPP/ET, where GPP is gross primary productivity and ET is evapotranspiration) and factors affecting it. Our seasonal dynamics results indicated single-peak variation of WUE in CBS, NM, and HBGC, which were affected by air temperature (Ta) and leaf area index (LAI), through their effects on the partitioning of evapotranspiration (ET) into transpiration (T) (i.e., T/ET). In DHS, WUE was higher at the beginning and the end of the year, and minimum in summer. Ta and soil water content affected the seasonal dynamics of WUE through their effects on GPP/T. Our results indicate that seasonal dynamics of WUE were different because factors affecting the seasonal dyn...

  13. Seasonal variation in dust events and the causes of the variation in the Tarim Basin,China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    We analyzed dust event occurrence and its seasonal distribution at 16 sites in the Tarim Basin,China.Although the overall frequency of dust events was the highest in spring in this region,its variation in other seasons could be classified into three patterns:(1) frequency of dust events in autumn > that in summer > that in winter(at the Kashi and Kuche sites);(2) frequency in summer > that in winter > that in autumn(at the Ruoqiang site);and(3) frequency in summer > that in autumn > that in winter(at all other areas of the Tarim Basin).The frequency of dust events and their seasonal variations in the Tarim Basin were mainly controlled by wind speed and locally available dust sources;the former was the key control when dust sources did not differ significantly.The seasonal variation in evaporation had a smaller,but still significant effect on the frequency of dust events.

  14. Seasonal Variations in Mood and Behavior in Romanian Postgraduate Students

    Directory of Open Access Journals (Sweden)

    Joseph J. Soriano

    2007-01-01

    Full Text Available To our knowledge, this paper is the first to estimate seasonality of mood in a predominantly Caucasian sample, living in areas with hot summers and a relative unavailability of air conditioning. As a summer pattern of seasonal depression was previously associated with a vulnerability to heat exposure, we hypothesized that those with access to air conditioners would have a lower rate of summer seasonal affective disorder (SAD compared to those without air conditioning. A convenience sample of 476 Romanian postgraduate students completed the Seasonal Pattern Assessment Questionnaire (SPAQ, which was used to calculate a global seasonality score (GSS and to estimate the rates of winter- and summer-type SAD. The ratio of summer- vs. winter-type SAD was compared using multinomial probability distribution tests. We also compared the ratio of summer SAD in individuals with vs. without air conditioners. Winter SAD and winter subsyndromal SAD (S-SAD were significantly more prevalent than summer SAD and summer S-SAD. Those with access to air conditioners had a higher, rather than a lower, rate of summer SAD. Our results are consistent with prior studies that reported a lower prevalence of summer than winter SAD in Caucasian populations. Finding an increased rate of summer SAD in the minority of those with access to air conditioners was surprising and deserves replication.

  15. Seasonal dynamics of extraradical mycelium and mycorrhizas in a black truffle (Tuber melanosporum) plantation.

    Science.gov (United States)

    Queralt, Mikel; Parladé, Javier; Pera, Joan; DE Miguel, Ana María

    2017-08-01

    Seasonal dynamics of black truffle (Tuber melanosporum) extraradical mycelium as well as the associated mycorrhizal community have been evaluated in a 16-year-old plantation with productive and non-productive trees. Mycelium biomass was seasonally quantified by real-time PCR over two consecutive years and the correlation with environmental variables explored. Extraradical mycelium biomass varied seasonally and between the two consecutive years, being correlated with the precipitation that occurred 1 month before sampling. In addition, productive trees had more mycelium in the brûlé area than non-productive trees did. The ectomycorrhizal community composition inside the burnt areas was seasonally evaluated during a year. Ten mycorrhizal morphotypes were detected; T. melanosporum was the most abundant in productive and non-productive trees. Black truffle mycorrhizas were more abundant (mycorrhizal tips per unit of soil volume) in productive trees, and no seasonal variation was observed. The occurrence of black truffle mycorrhizas was significantly and positively correlated with the biomass of extraradical mycelium. The mycorrhizal community within the brûlé areas was significantly different between productive and non-productive trees, and no variation was detected between seasons. The assessment of the fungal vegetative structures in a mature plantation is of paramount importance to develop trufficulture methods based on the knowledge of the biological cycle of the fungus and its relationships with the associated ectomycorrhizal communities.

  16. Seasonal methane dynamics in three temperate grasslands on peat

    DEFF Research Database (Denmark)

    Schäfer, Carolyn; Elsgaard, Lars; Hoffmann, Carl Christian;

    2012-01-01

    Background and Aims Drained peatlands are considered to be insignificant CH4 sources, but the effect of drainage on CH4 dynamics has not been extensively studied. We investigated seasonal dynamics of CH4 in two fen peat soils and one bog peat soil under permanent grassland in Denmark. Methods Soil...... of aerenchymous plants should be considered before dismissing grasslands on peat as CH4 sources....

  17. Seasonal Effect of Geomorphological Chronosequence Features on Soil Biota Dynamics

    Institute of Scientific and Technical Information of China (English)

    S.PEN-MOURATOV; N.GENZER; N.SHUKUROV; J.PLAKHT; Y.STEINBERGER

    2010-01-01

    Numerous studies have been devoted to the physical-chemical weathering processes leading to the creation of unique soil formations having their own history that induce soil-biotic diversity.However,the extent to which unique geomorphic formations influence soil biotic seasonal variation is not clear.Our aim was to define seasonal variations of soil biota in soils of different-aged terraces of the Makhtesh Ramon anticline erosional cirque in southern Israel.The strong effect of Makhtesh Ramon(Ramon crater)erosional fluvial terrace age initiated by climatic changes during the Late Pleistocene-Early Holocene period on seasonal variations in both soil properties and the abundance and composition of soil biota were demonstrated.However,age dependence was not constant and values for observed soil properties and microbial activity were negligible between younger and older terraces for certain seasons,while free-living nematodes along with bacterial-feeding group were strongly dependent on the geomorphic features of the ages throughout the study period.

  18. A Theoretical Approach to Understanding Population Dynamics with Seasonal Developmental Durations

    Science.gov (United States)

    Lou, Yijun; Zhao, Xiao-Qiang

    2017-04-01

    There is a growing body of biological investigations to understand impacts of seasonally changing environmental conditions on population dynamics in various research fields such as single population growth and disease transmission. On the other side, understanding the population dynamics subject to seasonally changing weather conditions plays a fundamental role in predicting the trends of population patterns and disease transmission risks under the scenarios of climate change. With the host-macroparasite interaction as a motivating example, we propose a synthesized approach for investigating the population dynamics subject to seasonal environmental variations from theoretical point of view, where the model development, basic reproduction ratio formulation and computation, and rigorous mathematical analysis are involved. The resultant model with periodic delay presents a novel term related to the rate of change of the developmental duration, bringing new challenges to dynamics analysis. By investigating a periodic semiflow on a suitably chosen phase space, the global dynamics of a threshold type is established: all solutions either go to zero when basic reproduction ratio is less than one, or stabilize at a positive periodic state when the reproduction ratio is greater than one. The synthesized approach developed here is applicable to broader contexts of investigating biological systems with seasonal developmental durations.

  19. Skill improvement of dynamical seasonal Arctic sea ice forecasts

    NARCIS (Netherlands)

    Krikken, Folmer; Schmeits, Maurice; Vlot, Willem; Guemas, Virginie; Hazeleger, Wilco

    2016-01-01

    We explore the error and improve the skill of the outcome from dynamical seasonal Arctic sea ice reforecasts using different bias correction and ensemble calibration methods. These reforecasts consist of a five-member ensemble from 1979 to 2012 using the general circulation model EC-Earth. The

  20. Skill improvement of dynamical seasonal Arctic sea ice forecasts

    NARCIS (Netherlands)

    Krikken, Folmer; Schmeits, Maurice; Vlot, Willem; Guemas, Virginie; Hazeleger, Wilco

    2016-01-01

    We explore the error and improve the skill of the outcome from dynamical seasonal Arctic sea ice reforecasts using different bias correction and ensemble calibration methods. These reforecasts consist of a five-member ensemble from 1979 to 2012 using the general circulation model EC-Earth. The ra

  1. Seasonal Population Dynamics of Three Potato Pests in Washington State.

    Science.gov (United States)

    D'Auria, Elizabeth M; Wohleb, Carrie H; Waters, Timothy D; Crowder, David W

    2016-08-01

    Pest phenology models allow producers to anticipate pest outbreaks and deploy integrated pest management (IPM) strategies. Phenology models are particularly useful for cropping systems with multiple economically damaging pests throughout a season. Potato (Solanum tuberosum L.) crops of Washington State, USA, are attacked by many insect pests including the potato tuberworm (Phthorimaea operculella Zeller), the beet leafhopper (Circulifer tenellus Baker), and the green peach aphid (Myzus persicae Sulzer). Each of these pests directly damages potato foliage or tubers; C. tenellus and M. persicae also transmit pathogens that can drastically reduce potato yields. We monitored the seasonal population dynamics of these pests by conducting weekly sampling on a network of commercial farms from 2007 to 2014. Using these data, we developed phenology models to characterize the seasonal population dynamics of each pest based on accumulated degree-days (DD). All three pests exhibited consistent population dynamics across seasons that were mediated by temperature. Of the three pests, C. tenellus was generally the first detected in potato crops, with 90% of adults captured by 936 DD. In contrast, populations of P. operculella and M. persicae built up more slowly over the course of the season, with 90% cumulative catch by 1,590 and 2,634 DD, respectively. Understanding these seasonal patterns could help potato producers plan their IPM strategies while allowing them to move away from calendar-based applications of insecticides. More broadly, our results show how long-term monitoring studies that explore dynamics of multiple pest species can aid in developing IPM strategies in crop systems.

  2. Seasonal variation of the surface North Equatorial Countercurrent (NECC) in the western Pacific Ocean

    Science.gov (United States)

    Zhao, Jun; Li, Yuanlong; Wang, Fan

    2016-11-01

    The North Equatorial Countercurrent (NECC) is an important zonal flow in the upper circulation of the tropical Pacific Ocean, which plays a vital role in the heat budget of the western Pacific warm pool. Using satellite-derived data of ocean surface currents and sea surface heights (SSHs) from 1992 to 2011, the seasonal variation of the surface NECC in the western tropical Pacific Ocean was investigated. It was found that the intensity (INT) and axis position (Y CM ) of the surface NECC exhibit strikingly different seasonal fluctuations in the upstream (128°-136°E) and downstream (145°-160°E) regions. Of the two regions, the seasonal cycle of the upstream NECC shows the greater interannual variability. Its INT and YCM are greatly influenced by variations of the Mindanao Eddy, Mindanao Dome (MD), and equatorial Rossby waves to its south. Both INT and Y CM also show semiannual signals induced by the combined effects of equatorial Rossby waves from the Central Pacific and local wind forcing in the western Pacific Ocean. In the downstream region, the variability of the NECC is affected by SSH anomalies in the MD and the central equatorial Pacific Ocean. Those in the MD region are especially important in modulating the YCM of the downstream NECC. In addition to the SSH-related geostrophic flow, zonal Ekman flow driven by meridional wind stress also plays a role, having considerable impact on INT variability of the surface NECC. The contrasting features of the variability of the NECC in the upstream and downstream regions reflect the high complexity of regional ocean dynamics.

  3. Seasonal variation of macromedusae (Cnidaria at North Bay, Florianópolis, southern Brazil

    Directory of Open Access Journals (Sweden)

    Miodeli Nogueira Júnior

    2010-06-01

    Full Text Available Seasonal variation of large medusae abundance and biomass was studied in the North Bay, Santa Catarina, southern Brazil (27°30'S, 48° 32'W, from February to December 2005. Collecting was conducted seasonally with the help of fishing bottom trawl in 30-minute sections (12 in summer, 18 in each of the remaining seasons in six stations, totaling 66 samples. Eight species were found: the hydrozoans Aequorea sp., Olindias sambaquiensis Müller, 1861, and Rhacostoma atlantica L. Agassiz, 1850; the cubozoans Chiropsalmus quadrumanus (Müller, 1859 and Tamoya haplonema Müller, 1859, and the scyphozoans Aurelia sp., Chrysaora lactea Eschscholtz, 1829 and Lychnorhiza lucerna Haeckel, 1880. Capture rates were low, up to 38 indiv. ha-1, and only ~47% of the samples were positive for jellyfish, comprising 206 individuals. Medusae abundance and species richness clearly changed from one season to another, but did not vary between the sites. Higher species richness (7 out of 8 and greater abundances were recorded during the fall (~60% and 72% of all medusae individuals and biomass respectively. Specific frequency of capture varied from 1.5 to 29% and C. lactea was the only species found in more than 25% of the samples. The three most common species dominated in different periods of the year: C. lactea during fall (78% of individuals and 60% of biomass, R. atlantica during winter (90% of individuals and 17% of biomass, and O. sambaquiensis in spring (78% of individuals and 40% of biomass. Only two individuals were caught during summer, one C. lactea and one R. atlantica. The results offer a general picture of the distribution of the macromedusae in the North Bay, but a continuous monitoring is desirable for a more detailed knowledge on the jellyfish dynamics in the Brazilian coastal waters.

  4. Seasonal variations of Saturn's auroral acceleration region deduced from spectra of auroral radio emissions

    Science.gov (United States)

    Kimura, T.; Lamy, L.; Tao, C.; Badman, S. V.; Cecconi, B.; Zarka, P.; Morioka, A.; Miyoshi, Y.; Kasaba, Y.; Maruno, D.; Fujimoto, M.

    2012-09-01

    Multi-instrumental surveys of Saturn's magnetosphere by Cassini have indicated that auroral radio emissions (Saturnian Kilometric Radiation, SKR), aurorae at UV and IR wavelengths and Energetic Neutral Atoms (ENA) from the inner magnetosphere exhibit periodic behavior at around Saturn's rotational period with the north-south asymmetry and seasonal variations [e.g., Gurnett et al., 2010; Mitchell et al., 2009; Nichols et al., 2010]. These rotationally periodic phenomena are suggestive of distinct magnetosphere-ionosphere coupling current systems, rotating at different periods in the northern and southern hemispheres [e.g., Andrews et al., 2010]. These phenomena suggest that the magnetosphere-ionosphere coupling process and associated energy dissipation process (aurora & SKR) are dynamically dependent on both magnetospheric rotations and long-term conditions of the magnetosphere/ionosphere.

  5. Observing seasonal variations of sea surface wind speed and significant wave height using TOPEX altimetry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    One year of ocean topography experiment (TOPEX) altimeter data are used to study the seasonal variations of global sea surface wind speed and significant wave height. The major wind and wave zones of the world oceans are precisely identified, their seasonal variability and characteristics are quantitatively analyzed, and the diversity of global wind speed seasonality and the variability of significant wave height in response to sea surface wind speed are also revealed.

  6. Seasonal variation of bacterial endophytes in urban trees

    Directory of Open Access Journals (Sweden)

    Shu Yi eShen

    2015-05-01

    Full Text Available Bacterial endophytes, non-pathogenic bacteria residing within plants, contribute to the growth and development of plants and their ability to adapt to adverse conditions. In order to fully exploit the capabilities of these bacteria, it is necessary to understand the extent to which endophytic communities vary between species and over time. The endophytes of Acer negundo, Ulmus pumila and Ulmus parvifolia were sampled over three seasons and analyzed using culture dependent and independent methods (culture on two media, terminal restriction fragment length polymorphism, and tagged pyrosequencing of 16S ribosomal amplicons. The majority of culturable endophytes isolated were Actinobacteria, and all the samples harbored Bacillus, Curtobacterium, Frigoribacterium, Methylobacterium, Paenibacilllus and Sphingomonas species. Regardless of culture medium used, only the culturable communities obtained in the winter for A. negundo could be distinguished from those of Ulmus spp.. In contrast, the nonculturable communities were dominated by Proteobacteria and Actinobacteria, particularly Erwinia, Ralstonia and Sanguibacter spp.. The presence and abundance of various bacterial classes and phyla changed with the changing seasons. Multivariate analysis on the culture independent data revealed significant community differences between the endophytic communities of A. negundo and Ulmus spp., but overall season was the main determinant of endophytic community structure. This study suggests investigations of the studies ofendophytic populations of urban trees should expect to find significant seasonal and species-specific community differences and sampling should proceed accordingly.

  7. Seasonal variation of PAHs in marshy sediments from Warri City ...

    African Journals Online (AJOL)

    The objective of this study is to compare the level of PAHs in dry and rainy season and .... The people of Warri (this study location) feed largely on fish and most ... aluminium foil and properly preserved by cooling in a ... concentrated sample was injected by means of exmire micro .... This could be related to the characteristic ...

  8. Seasonal variation in sperm characteristics of boars in southern Uruguay

    Directory of Open Access Journals (Sweden)

    Hugo Petrocelli

    2015-01-01

    Full Text Available The objective of this study was to evaluate the effects of season, natural photoperiod, and room temperature at the housing facility on boar semen characteristics in Uruguay (34º66'S; 56º29'W. For this purpose, 117 ejaculates, obtained from eight adult males collected through 12 consecutive months, were assessed for sperm viability, DNA integrity, abnormalities (total, primary, and secondary, ejaculate volume, and sperm concentration. Viability, total and primary abnormalities, volume, and sperm concentration were affected by season. Sperm viability, volume, and sperm concentration were affected by natural photoperiod. In general, autumn and the decreasing photoperiod had a negative impact on most of the semen characteristics, except for volume. Housing temperature did not affect semen characteristics. In boars living in temperate climates, semen quality is negatively affected during autumn and is related to photoperiod changes; however, the effects of temperature changes in housingdo not affect these seminal characteristics. In this scenario, seasonal differences in semen quality may have a negative effect on sow fertilization. Consequently, semen quality control especially during autumn is imperative for the best boar selection to be used for insemination purposes. Seasonal differences in semen quality may have a negative effect on sow reproductive performance. This issue will be addressed in a future investigation.

  9. Seasonal variations of airborne pollen in Allahabad, India.

    Science.gov (United States)

    Sahney, Manju; Chaurasia, Swati

    2008-01-01

    Using a Burkard 7-day volumetric sampler a survey of airborne pollen grains in Allahabad was carried out from December 2004--November 2005 to assess the qualitative and quantitative occurrence of pollen grains during different months of the year, and to characterize the pollen seasons of dominant pollen types in the atmosphere of Allahabad. 80 pollen types were identified out of the total pollen catch of 3,416.34 pollen grains/m(3). Bulk of the pollen originated from anemophilous trees and grasses. Thirteen pollen types recorded more than 1 % of the annual total pollen catch. Holoptelea integrifolia formed the major component of the pollen spectrum constituting 46.21 % of the total pollen catch followed by Poaceae, Azadirachta indica, Ailanthus excelsa, Putranjiva roxburghii, Parthenium hysterophorus, Ricinus communis, Brassica compestris, Amaranthaceae/Chenopodiaceae, Madhuca longifolia, Syzygium cumini, other Asteraceae and Aegle marmelos. Highest pollen counts were obtained in the month of March and lowest in July. The pollen types recorded marked the seasonal pattern of occurrence in the atmosphere. February-May was the principal pollen season with maximum number of pollen counts and pollen types. Chief sources of pollen during this period were arboreal taxa. September-October was the second pollen season with grasses being the main source of pollen. Airborne pollen spectrum reflected the vegetation of Allahabad, except for Alnus sp., which grows in the Himalayan region. A significant negative correlation was found of daily pollen counts with minimum temperature, relative humidity and rainfall.

  10. Seasonal variation in Internet searches for vitamin D.

    Science.gov (United States)

    Moon, Rebecca J; Curtis, Elizabeth M; Davies, Justin H; Cooper, Cyrus; Harvey, Nicholas C

    2017-12-01

    Internet search rates for "vitamin D" were explored using Google Trends. Search rates increased from 2004 until 2010 and thereafter displayed a seasonal pattern peaking in late winter. This knowledge could help guide the timing of public health interventions aimed at managing vitamin D deficiency.

  11. Seasonal variation of secondary cosmic rays in the low polar atmosphere

    Science.gov (United States)

    Germanenko, Alexey; Balabin, Yury

    Monitoring of different kind of secondary cosmic rays in the low atmosphere is carried out for some years in the Polar Geophysical Institute. At the present moment two monitoring stations (Apatity, Murmansk region and Barentsburg, Spitzbergen) are in operation. Additionally to conventional 18-NM-64 neutron monitor (NM) there are leadless 4-NM-64 section (LLNM), thermal neutron detector (TND) and scintillation detector of gamma-ray (SDG) of 20-400 keV energy range. SDG has 5 cm lead shield at bottom and sides, accepts radiation only from the atmosphere. In a row of neutron detectors from NM to TND seasonal variation grows up from 0 to ˜ 10 %. The distinct and big seasonal variation (˜ 30 %) is on SDG detector. Low energy gamma-rays are caused of pion and muon decay, first of all low energy muons. It was suggested muon seasonal variation, depending on atmosphere temperature and seasonal condition, determines the SDG-variation.

  12. Seasonal variations in the sediment biogenic properties of a tropical mangrove environment, southwest coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, M.; Jacob, J.; Nisha, P.A.; Martin, G.D.; Srinivas, K.; Sheeba, P.; Laluraj, C.M.; Joseph, T.; Balachandran, K.K.

    environments. Principal component analysis showed that the biochemical properties are uniformly influenced by seasonal and spatial variations. Higher concentrations of sediment protein over carbohydrate indicate an efficient mineralization leading to the non...

  13. Seasonal variation of wind direction fluctuations vs Pasquill stabilities in complex terrain

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.; Murthy, K.P.R.V.

    The authors have studied the seasonal variation of sigma theta (the standard deviation of wind direction fluctuations) vs Pasquill stabilities over complex terrain. It is found that the values of sigma theta are quite high in the month of April...

  14. Seasonal variations in biochemical composition of some seaweeds from Goa coast

    Digital Repository Service at National Institute of Oceanography (India)

    Sumitra-Vijayaraghavan; Rajagopal, M.D.; Wafar, M.V.M.

    high in H. musciformis, whereas P. tetrastromatica, C. media and U. fasciata were rich in protein. The biochemical constituents in general did not show marked seasonal variations and it was attributed to the reproductive pattern of the algae studied...

  15. Seasonal and biological variation of urinary epinephrine, norepinephrine, and cortisol in healthy women

    DEFF Research Database (Denmark)

    Hansen, Åse Marie; Garde, A H; Skovgaard, L T

    2001-01-01

    There is a significant circadian and seasonal periodicity in various endocrine functions. The present study describes the within-day and seasonal fluctuation for urinary catecholamines and cortisol and estimates the within- (CV(i)) and between-subject (CV(g)) coefficients of variation for healthy...

  16. Seasonal Variations in Drag Coefficient over a Sastrugi-Covered Snowfield in Coastal East Antarctica

    Science.gov (United States)

    Amory, Charles; Gallée, Hubert; Naaim-Bouvet, Florence; Favier, Vincent; Vignon, Etienne; Picard, Ghislain; Trouvilliez, Alexandre; Piard, Luc; Genthon, Christophe; Bellot, Hervé

    2017-02-01

    The surface of windy Antarctic snowfields is subject to drifting snow, which leads to the formation of sastrugi. In turn, sastrugi contribute to the drag exerted by the snow surface on the atmosphere and hence influence drifting snow. Although the surface drag over rough sastrugi fields has been estimated for individual locations in Antarctica, its variation over time and with respect to drifting snow has received little attention. Using year-round data from a meteorological mast, seasonal variations in the neutral drag coefficient at a height of 10 m (C_{{ DN}10}) in coastal Adelie Land are presented and discussed in light of the formation and behaviour of sastrugi based on observed aeolian erosion patterns. The measurements revealed high C_{{ DN}10} values (≥ 2 × 10^{-3}) and limited drifting snow (35% of the time) in summer (December-February) versus lower C_{{ DN}10} values (≈ 1.5 × 10^{-3}) associated with more frequent drifting snow (70% of the time) in winter (March-November). Without the seasonal distinction, there was no clear dependence of C_{{ DN}10} on friction velocity or wind direction, but observations revealed a general increase in C_{{ DN}10} with rising air temperature. The main hypothesis defended here is that higher temperatures increase snow cohesion and the development of sastrugi just after snow deposition while inhibiting the sastrugi streamlining process by raising the erosion threshold. This increases the contribution of the sastrugi form drag to the total surface drag in summer when winds are lighter and more variable. The analysis also showed that, in the absence of erosion, single snowfall events can reduce C_{{ DN}10} to 1 × 10^{-3} due to the burying of pre-existing microrelief under newly deposited snow. The results suggest that polar atmospheric models should account for spatial and temporal variations in snow surface roughness through a dynamic representation of the sastrugi form drag.

  17. Solar cycle and seasonal variations of the low latitude OI 630 nm nightglow

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, Y.; Takahashi, H.; Bittencourt, J.A.; Sobral, J.H.A.; Teixeira, N.R.

    1988-02-01

    Regular zenith measurements of the OI 630 nm nightglow emission have been carried out at Cachoeira Paulista, Brazil, since 1975. The long series of observations during the period 1975-1982, including the ascending phase of the last solar cycle, permitted studies of solar cycle effects and seasonal variations. A large intensity increase, about seven times, from low solar activity to high solar activity has been observed. Also, the seasonal-nocturnal intensity variations show large changes between years of low and high solar activity. The characteristics of the variations observed are closely related to the equatorial electric field variations, since the observation site is under the southern equatorial ionospheric anomaly crest.

  18. Seasonal Variation of the East Asian Subtropical Westerly Jet and Its Association with the Heating Field over East Asia

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The structure and seasonal variation of the East Asian Subtropical Westerly Jet (EAWJ) and associations with heating fields over East Asia are examined by using NCEP/NCAR reanalysis data.Obvious differences exist in the westerly jet intensity and location in different regions and seasons due to the ocean-land distribution and seasonal thermal contrast, as well as the dynamic and thermodynamic impacts of the Tibetan Plateau. In winter, the EAWJ center is situated over the western Pacific Ocean and the intensity is reduced gradually from east to west over the East Asian region. In summer, the EAWJ center is located over the north of the Tibetan Plateau and the jet intensity is reduced evidently compared with that in winter. The EAWJ seasonal evolution is characterized by the obvious longitudinal inconsistency of the northward migration and in-phase southward retreat of the EAWJ axis. A good correspondence between the seasonal variations of EAWJ and the meridional differences of air temperature (MDT) in the mid-upper troposphere demonstrates that the MDT is the basic reason for the seasonal variation of EAWJ. Correlation analyses indicate that the Kuroshio Current region to the south of Japan and the Tibetan Plateau are the key areas for the variations of the EAWJ intensities in winter and in summer,respectively. The strong sensible and latent heating in the Kuroshio Current region is closely related to the intensification of EAWJ in winter. In summer, strong sensible heating in the Tibetan Plateau corresponds to the EAWJ strengthening and southward shift, while the weak sensible heating in the Tibetan Plateau is consistent with the EAWJ weakening and northward migration.

  19. Human birth seasonality: latitudinal gradient and interplay with childhood disease dynamics.

    Science.gov (United States)

    Martinez-Bakker, Micaela; Bakker, Kevin M; King, Aaron A; Rohani, Pejman

    2014-05-22

    More than a century of ecological studies have demonstrated the importance of demography in shaping spatial and temporal variation in population dynamics. Surprisingly, the impact of seasonal recruitment on infectious disease systems has received much less attention. Here, we present data encompassing 78 years of monthly natality in the USA, and reveal pronounced seasonality in birth rates, with geographical and temporal variation in both the peak birth timing and amplitude. The timing of annual birth pulses followed a latitudinal gradient, with northern states exhibiting spring/summer peaks and southern states exhibiting autumn peaks, a pattern we also observed throughout the Northern Hemisphere. Additionally, the amplitude of United States birth seasonality was more than twofold greater in southern states versus those in the north. Next, we examined the dynamical impact of birth seasonality on childhood disease incidence, using a mechanistic model of measles. Birth seasonality was found to have the potential to alter the magnitude and periodicity of epidemics, with the effect dependent on both birth peak timing and amplitude. In a simulation study, we fitted an susceptible-exposed-infected-recovered model to simulated data, and demonstrated that ignoring birth seasonality can bias the estimation of critical epidemiological parameters. Finally, we carried out statistical inference using historical measles incidence data from New York City. Our analyses did not identify the predicted systematic biases in parameter estimates. This may be owing to the well-known frequency-locking between measles epidemics and seasonal transmission rates, or may arise from substantial uncertainty in multiple model parameters and estimation stochasticity.

  20. Annual variation in foraging ecology of prothonotary warblers during the breeding season

    Science.gov (United States)

    Petit, L.J.; Petit, D.R.; Petit, K.E.; Fleming, W.J.

    1990-01-01

    We studied foraging ecology of Prothonotary Warblers (Protonotaria citrea) along the Tennessee River in west-central Tennessee during the breeding seasons of 1984-1987. We analyzed seven foraging variables to determine if this population exhibited annual variation in foraging behavior. Based on nearly 3,000 foraging maneuvers, most variables showed significant interyear variation during the four prenestling and three nestling periods we studied. This interyear variation probably was due -to proximate, environmental cues--such as distribution and abundance of arthropods--which, in turn, were influenced by local weather conditions. Researchers should consider the consequences of combining foraging behavior data collected in different years, because resolution of ecological trends may be sacrificed by considering only general patterns of foraging ecology and not the dynamics of those activities. In addition, because of annual variability, foraging data collected in only one year, regardless of the number of observations gathered, may not provide an accurate concept of the foraging ecology in insectivorous birds.

  1. Seasonal and interannual variations in pigments in the Adriatic Sea

    Indian Academy of Sciences (India)

    Mira Morović

    2002-09-01

    Spatial and temporal variability of pigments was studied from the CZCS satellite data and from in situ chlorophyll and transparency for the period 1979-1985. The three Adriatic sites, Northern, Middle, and Southern Adriatic are differently in oceanographic parameters. The differences between seasonal in situ chlorophyll and remotely sensed pigment concentrations (from CZCS satellite data) from the Adriatic are large in winter. Through the correlation analysis, pigments were compared to meteo-oceanographic and hydrological parameters from different Adriatic sites. The PCA (principal component analysis) was applied to the pigment data series and significant components were compared. Different correlations are obtained for warm and cold periods of the year pointing to seasonal differences in the underlying mechanism of pigment variability. The first PC is in more parameters seem to in field, than in the cold period. The pigments in the Adriatic are in good correlation to a number of hydrologic and meteo-oceanographic factors.

  2. Seasonal variations of troposheric ozone at Natal, Brazil

    Science.gov (United States)

    Logan, J. A.; Kirchhoff, V. W. J. H.

    1986-01-01

    An analysis of ozone measurements from Natal, Brazil (6 deg S, 35 W), with a focus on the seasonal behavior in the troposphere, is presented. The amplitude of seasonal cycle at Natal is much larger than at Panama (9 deg N), the only other tropical site for which similar data are available. Concentrations of ozone in the middle troposphere in the southern spring are unexpectedly high, 60-70 ppb, similar to values found at northern midlatitudes in summer, and larger by 20-30 ppb than values found at Panama and at southern midlatitudes. It is suggested that photochemical production of ozone associated with emissions of CO, hydrocarbons, and NO(x) from biomass burning may contribute significantly to the high values of ozone, but note that stratospheric intrusions could also play a role. The data available at present do not permit a definitive evaluation of the relative importance of these two sources of ozone. The data from Natal, in combination with recent aircraft and surface data, show that tropical ozone exhibits strong spatial and temporal inhomogeneities. The distribution of tropospheric ozone appears to be considerably more complex than the traditional view, which suggested a northern midlatitude maximum and north/-south hemispheric asymmetry. The seasonal cycle in the total column of ozone at Natal appears to mirror the behavior of the tropospheric contribution to the ozone column rather than the stratospheric contribution, and this may account for differences in the annual cycle of the total column at Natal versus other tropical locations.

  3. Latitudinal and Seasonal Investigations of Storm-Time TEC Variation

    Science.gov (United States)

    Adimula, I. A.; Oladipo, O. A.; Adebiyi, S. J.

    2016-07-01

    The ionosphere responds markedly and unpredictably to varying magnetospheric energy inputs caused by solar disturbances on the geospace. Knowledge of the impact of the space weather events on the ionosphere is important to assess the environmental effect on the operations of ground- and space-based technologies. Thus, global positioning system (GPS) measurements from the international GNSS service (IGS) database were used to investigate the ionospheric response to 56 geomagnetic storm events at six different latitudes comprising the northern and southern hemispheres in the Afro-European sector. Statistical distributions of total electron content (TEC) response show that during the main phase of the storms, enhancement of TEC is more pronounced in most of the seasons, regardless of the latitude and hemisphere. However, a strong seasonal dependence appears in the TEC response during the recovery phase. Depletion of TEC is majorly observed at the high latitude stations, and its appearance at lower latitudes is seasonally dependent. In summer hemisphere, the depletion of TEC is more pronounced in nearly all the latitudinal bands. In winter hemisphere, enhancement as well as depletion of TEC is observed over the high latitude, while enhancement is majorly observed over the mid and low latitudes. In equinoxes, the storm-time TEC distribution shows a fairly consistent characteristic with the summer distribution, particularly in the northern hemisphere.

  4. Skill improvement of dynamical seasonal Arctic sea ice forecasts

    Science.gov (United States)

    Krikken, Folmer; Schmeits, Maurice; Vlot, Willem; Guemas, Virginie; Hazeleger, Wilco

    2016-05-01

    We explore the error and improve the skill of the outcome from dynamical seasonal Arctic sea ice reforecasts using different bias correction and ensemble calibration methods. These reforecasts consist of a five-member ensemble from 1979 to 2012 using the general circulation model EC-Earth. The raw model reforecasts show large biases in Arctic sea ice area, mainly due to a differently simulated seasonal cycle and long term trend compared to observations. This translates very quickly (1-3 months) into large biases. We find that (heteroscedastic) extended logistic regressions are viable ensemble calibration methods, as the forecast skill is improved compared to standard bias correction methods. Analysis of regional skill of Arctic sea ice shows that the Northeast Passage and the Kara and Barents Sea are most predictable. These results show the importance of reducing model error and the potential for ensemble calibration in improving skill of seasonal forecasts of Arctic sea ice.

  5. Seasonal timing of first rain storms affects rare plant population dynamics

    Science.gov (United States)

    Levine, J.M.; McEachern, A.K.; Cowan, C.

    2011-01-01

    A major challenge in forecasting the ecological consequences of climate change is understanding the relative importance of changes to mean conditions vs. changes to discrete climatic events, such as storms, frosts, or droughts. Here we show that the first major storm of the growing season strongly influences the population dynamics of three rare and endangered annual plant species in a coastal California (USA) ecosystem. In a field experiment we used moisture barriers and water addition to manipulate the timing and temperature associated with first major rains of the season. The three focal species showed two- to fivefold variation in per capita population growth rates between the different storm treatments, comparable to variation found in a prior experiment imposing eightfold differences in season-long precipitation. Variation in germination was a major demographic driver of how two of three species responded to the first rains. For one of these species, the timing of the storm was the most critical determinant of its germination, while the other showed enhanced germination with colder storm temperatures. The role of temperature was further supported by laboratory trials showing enhanced germination in cooler treatments. Our work suggests that, because of species-specific cues for demographic transitions such as germination, changes to discrete climate events may be as, if not more, important than changes to season-long variables.

  6. Species composition and seasonal variation of butterflies in Dalma Wildlife Sanctuary, Jharkhand, India

    Directory of Open Access Journals (Sweden)

    S.K. Verma

    2009-05-01

    Full Text Available Dalma Wildlife Sanctuary is located 10km from Jamshedpur in Jharkhand, India. The species composition and seasonal variation of butterflies was analyzed in this sanctuary over the course of 2 years. A total of 39 species belonging to 31 genera and 4 families were identified. Of these, Nymphalidae and Pieridae were found to be the dominant families, in comparison to Lycaenidae and Papilionidae. The monthly diversity was calculated by using the Shannon-Weiner diversity index. The highest diversity was found during late winter and spring while a comparatively low diversity was observed during the rainy season and summer. Nymphalidae showed the greatest variation with respect to distribution of species richness throughout the year. Nymphalidae and Lycaenidae showed greatest species richness and relative abundance during the rainy season. Little seasonal variation in species richness was observed in case of families Pieridae and Papilionidae

  7. Seasonal variations in composting process of dead poultry birds.

    Science.gov (United States)

    Sivakumar, K; Saravana Kumar, V Ramesh; Jagatheesan, P N Richard; Viswanathan, K; Chandrasekaran, D

    2008-06-01

    Composting of dead birds with caged layer manure (CLM) and farm yard manure (FYM) was carried out to study the feasibility of composting as an alternative for disposal in Tamil Nadu State, India. The dead birds were sequentially layered with manure substrate and carbon source as per recipes formulated in mini-compost bins (4 x 4 x 4 feet). The temperature profile of both CLM and FYM group reached the peak by second week of composting and started declining steadily. The temperature profile was better during summer and monsoon and bins were able to maintain temperature above 60 degrees C (thermophilic) for 3-4 weeks. Season had no influence on attainment of peak temperature and it ranged between 51.8 and 70.4 degrees C. The persistency of thermophilic temperature (above 55 degrees C) was prolonged during summer (17.5-65 days) followed by monsoon (24-39 days) and winter (15.5-21.5 days). No putrefied or obnoxious odour or fly menace was observed during all the seasons of composting. The composting process took 107-127.5 days to finish during summer, 84.5-91 days in monsoon and 61.5-73.5 days in winter. The FYM was able to retain moisture higher (41-54% at the end of primary stage and 27.5-48.2% at the end of secondary stage) than CLM group (17.5-39.3% at primary stage and 20.4-33.5% in secondary stage). Weight reduction was more in FYM group (31.8-58.7%) than CLM group (19.3-48.6%). The volume reduction was uniform in all the seasons, it ranged between 39% and 59.3%.

  8. Seasonal and locational variations in children's play: implications for wellbeing.

    Science.gov (United States)

    Ergler, Christina R; Kearns, Robin A; Witten, Karen

    2013-08-01

    Physical activity, through independent outdoor play, has come to the fore as a way to improve children's health through it fostering healthy mental and social as well as physiological development. However, in many high-income countries children's autonomous play opportunities have diminished due to urban intensification and declining parental license. Regardless of this trend, children's play varies across countries, cities, cultures and seasons. This paper offers new insights into the complexities of play as a vital aspect of children's wellbeing. Within the context of New Zealand - whose citizens generally regard themselves as outdoor people - this paper explores why 'play' might resonate differently across localities and seasons. We contrast the play affordances provided by Auckland's central city (dominated by apartment living) with Beach Haven, a suburban area. We employed a multi-method approach and included 20 children and their parents who were recruited through school and summer holiday programs embracing different gender and ethnicities to reflect the general cultural mix of the respective neighbourhoods. We advance two arguments. First, we suggest that the rarity of children playing outdoors unsupervised normalises supervised indoor play and reduces children's opportunities to see outdoor play as an alternative to interior or supervised pastimes. Second, we follow Bourdieu's theory of practice to argue that the regard parents and children have towards outdoor play reflects locally constituted beliefs about what is seasonally 'appropriate' children's activity. We found that extra-curricular activities and supervised excursions are undertaken in the central city all year around and only vary between social groups by the type of destination. In the suburb, independent outdoor play in summer represents children's main business after school in ways that enhance their environmental literacy and potential future health gain. For others these symbolic values

  9. Seasonal dynamics and diversity of bacteria in retail oyster tissues.

    Science.gov (United States)

    Wang, Dapeng; Zhang, Qian; Cui, Yan; Shi, Xianming

    2014-03-03

    Oysters are one of the important vehicles for the transfer of foodborne pathogens. It was reported that bacteria could be bio-accumulated mainly in the gills and digestive glands. In artificially treated oysters, bacterial communities have been investigated by culture-independent methods after harvest. However, little information is available on the seasonal dynamics of bacterial accumulation in retail oyster tissues. In this study, retail oysters were collected from local market in different seasons. The seasonal dynamics and diversity of bacteria in oyster tissues, including the gills, digestive glands and residual tissues, were analyzed by denaturing gradient gel electrophoresis (DGGE). It was interesting that the highest bacterial diversity appeared in the Fall season, not in summer. Our results indicated that Proteobacteria was the predominant member (23/46) in oyster tissues. Our results also suggested that bacterial diversity in gills was higher than that in digestive glands and other tissues. In addition, not all the bacteria collected from surrounding water by gills were transferred to digestive glands. On the other hand, few bacteria were found in oyster tissues except in the gills. Therefore, the gills could be the best candidate target tissue for monitoring of pathogenic bacteria either to human or to oyster.

  10. Seasonal Gravity Field Variations from GRACE and Hydrological Models

    DEFF Research Database (Denmark)

    Andersen, Ole Baltazar; Hinderer, Jacques; Lemoine, Frank G.

    2004-01-01

    This study present an investigation of the newly released 18 monthly gravity field solutions from the GRACE twin space-crafts with emphasis on the global scale annual gravity field variations observed from GRACE and modeled from hydrological models as annual changes in terrestrial water storage....... Four global hydrological models covering the same period in 2002–2003 as the GRACE observations were investigated to for their mutual consistency in estimates of annual variation in terrestrial water storage and related temporal changes in gravity field. The hydrological models differ by a maximum of 2...... variation in gravity from GRACE is around 0.4 µGal (0.9 cm water layer thickness) on 2000 km length scales. This makes the GRACE observations of terrestrial water storage on global annual scales more accurate than present-day hydrological models....

  11. Variations in Growing-Season NDVI and Its Response to Permafrost Degradation in Northeast China

    Directory of Open Access Journals (Sweden)

    Jinting Guo

    2017-04-01

    Full Text Available Permafrost is extremely sensitive to climate change. The degradation of permafrost has strong and profound effects on vegetation. The permafrost zone of northeastern China is the second largest region of permafrost in China and lies on the south edge of the Eurasian cryolithozone. This study analyzed the spatiotemporal variations of the growing-season Normalization Difference Vegetation Index (NDVI in the permafrost zone of northeastern China and analyzed the correlation between NDVI and ground surface temperatures (GST during the years 1981–2014. Mean growing-season NDVI (MGS-NDVI experienced a marked increase of 0.003 year−1 across the entire permafrost zone. The spatial dynamics of vegetation cover had a high degree of heterogeneity on a per pixel scale. The MGS-NDVI value increased significantly (5% significance level in 80.57%, and this increase was mostly distributed in permafrost zone except for the western steppe region. Only 7.72% experienced a significant decrease in NDVI, mainly in the cultivated and steppe portions. In addition, MGS-NDVI increased significantly with increasing growing-season mean ground surface temperature (GS-MGST. Our results suggest that a warming of GS-MGST (permafrost degradation in the permafrost region of northeastern China played a positive role in increasing plant growth and activities. Although increasing ground surface temperature resulted in increased vegetation cover and growth in the short time of permafrost degradation, from the long term point of view, permafrost degradation or disappearance may weaken or even hinder vegetation activities.

  12. Spatial and seasonal variations of the contamination within water body of the Grand Canal, China

    NARCIS (Netherlands)

    Wang, X.L.; Han, Jingyi; Xu, L.G.; Zhang, Q.

    2010-01-01

    To delineate the character of contaminations in the Grand Canal, China, a three-year study (2004-2006) was conducted to investigate variations the water quality in the canal. Results showed that the variation of water quality within the Grand Canal was of there is remarkable spatial and seasonal het

  13. Circadian Rhythms of Locomotor Activity in Captive Birds and Mammals : Their Variations with Season and Latitude

    NARCIS (Netherlands)

    Daan, Serge; Aschoff, Jürgen

    1975-01-01

    1. The seasonal variations in time of daily onset and end of locomotor activity are described for 3 species of mammals and 5 species of birds kept in captivity at the arctic circle and at lower latitude. These variations are most pronounced at high latitude. 2. The duration of daily activity plotted

  14. Seasonal variation in Chironomid emergence from coastal pools

    Directory of Open Access Journals (Sweden)

    Alexander T. Egan

    2015-07-01

    Full Text Available Understanding the phenology of emergences can be useful in determining seasonal chironomid life cycle patterns, which are often influenced by ice cover and temperature in cold climates. Lake Superior is the largest lake in North America and with a mean surface temperature of 3.9 °C influences regional climate. Coastal pools at Isle Royale, a wilderness archipelago in the northern part of the lake, occur in dense patches on low-gradient volcanic bedrock between the lakeshore and forest, creating variable microhabitats for Chironomidae. Four sites were sampled monthly from April to October, 2010. Surface-floating pupal exuviae were collected from a series of pools in two zones: a lower zone near the lake influenced by wave splash, and an upper zone near the forest and influenced by upland runoff. We used Jaccard’s and Whittaker’s diversity indexes to test community similarity across months. Temperature loggers in pools collected hourly readings for most of the study. Assemblage emergences were stable in upper pools, with significant similarity across late spring and summer months. Assemblages were seasonally variable in lower pools, with significant dissimilarity across spring, summer, and fall months. Few species in either zone were unique to spring or fall months. However, many summer species in the splash zone had a narrow emergence period occurring during calm weather following distinct increases in mean water temperature. Regardless of input of cold lake water to the lower zone, pools from both zones generally had corresponding temperature trends.

  15. Potential impacts of seasonal variation on atrazine and metolachlor persistence in andisol soil.

    Science.gov (United States)

    Jaikaew, Piyanuch; Boulange, Julien; Thuyet, Dang Quoc; Malhat, Farag; Ishihara, Satoru; Watanabe, Hirozumi

    2015-12-01

    To estimate the potential effect of seasonal variation on the fate of herbicides in andisol soil, atrazine and metolachlor residues were investigated through the summer and winter seasons during 2013 and 2014 under field condition. The computed half-lives of atrazine and metolachlor in soil changed significantly through the two seasons of the trial. The half-lives were shorter in summer season with 16.0 and 23.5 days for atrazine and metolachlor, respectively. In contrast, the half-lives were longer during the winter season with 32.7 and 51.8 days for atrazine and metolachlor, respectively. The analysis of soil water balance suggested that more pesticide was lost in deeper soil layers through infiltration in summer than in winter. In addition, during the summer season, metolachlor was more likely to leach into deeper soil layer than atrazine possibly due to high water solubility of metolachlor.

  16. The Seasonal Dynamics of Artificial Nest Predation Rates along Edges in a Mosaic Managed Reedbed.

    Directory of Open Access Journals (Sweden)

    Iain Malzer

    Full Text Available Boundaries between different habitats can be responsible for changes in species interactions, including modified rates of encounter between predators and prey. Such 'edge effects' have been reported in nesting birds, where nest predation rates can be increased at habitat edges. The literature concerning edge effects on nest predation rates reveals a wide variation in results, even within single habitats, suggesting edge effects are not fixed, but dynamic throughout space and time. This study demonstrates the importance of considering dynamic mechanisms underlying edge effects and their relevance when undertaking habitat management. In reedbed habitats, management in the form of mosaic winter reed cutting can create extensive edges which change rapidly with reed regrowth during spring. We investigate the seasonal dynamics of reedbed edges using an artificial nest experiment based on the breeding biology of a reedbed specialist. We first demonstrate that nest predation decreases with increasing distance from the edge of cut reed blocks, suggesting edge effects have a pivotal role in this system. Using repeats throughout the breeding season we then confirm that nest predation rates are temporally dynamic and decline with the regrowth of reed. However, effects of edges on nest predation were consistent throughout the season. These results are of practical importance when considering appropriate habitat management, suggesting that reed cutting may heighten nest predation, especially before new growth matures. They also contribute directly to an overall understanding of the dynamic processes underlying edge effects and their potential role as drivers of time-dependent habitat use.

  17. Simulation of Asian Monsoon Seasonal Variations with Climate Model R42L9/LASG

    Institute of Scientific and Technical Information of China (English)

    王在志; 吴国雄; 吴统文; 宇如聪

    2004-01-01

    The seasonal variations of the Asian monsoon were explored by applying the atmospheric general circulation model R42L9 that was developed recently at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences (LASG/IAP/CAS). The 20-yr (1979-1998) simulation was done using the prescribed20-yr monthly SST and sea-ice data as required by Atmospheric Model Intercomparison Project (AMIP)Ⅱ in the model. The monthly precipitation and monsoon circulations were analyzed and compared with the observations to validate the model's performance in simulating the climatological mean and seasonal variations of the Asian monsoon. The results show that the model can capture the main features of the spatial distribution and the temporal evolution of precipitation in the Indian and East Asian monsoon areas. The model also reproduced the basic patterns of monsoon circulation. However, some biases exist in this model. The simulation of the heating over the Tibetan Plateau in summer was too strong. The overestimated heating caused a stronger East Asian monsoon and a weaker Indian monsoon than the observations. In the circulation fields, the South Asia high was stronger and located over the Tibetan Plateau. The western Pacific subtropical high was extended westward, which is in accordance with the observational results when the heating over the Tibetan Plateau is stronger. Consequently, the simulated rainfall around this area and in northwest China was heavier than in observations, but in the Indian monsoon area and west Pacific the rainfall was somewhat deficient.

  18. Seasonal variation in the essential oil of Pilocarpus microphyllus Stapf.

    Directory of Open Access Journals (Sweden)

    FRANCISCA S. N. TAVEIRA

    2003-03-01

    Full Text Available The essential oils of the leaves and fine stems of Pilocarpus microphyllus, collected on iron mineralized soil of the Serra de Carajás, Southeast of Pará State, Brazil, during the rainy and dry seasons, were obtained by hydrodistillation and analyzed by GC-MS. The main identified compounds were 2-tridecanone, beta-caryophyllene, 2-pentadecanone, caryophyllene oxide and germacrene D. Their percentage contents varied with the season, the greater values having been detected mainly in the rainy season. For 2-tridecanone and beta-caryophyllene the higher values were observed in the fine stem oils for the former, and in the leaf oils for the latter. For 2-pentadecanone, caryophyllene oxide and germacrene D they were also in the leaf oils. In general, the leaf oils were very distinguishable from those of fine stem oils, even in the same specimen.Os óleos essenciais das folhas e galhos finos de Pilocarpus microphyllus, coletado em solo mineralizado com ferro, na Serra de Carajás, Sudeste do Pará, Brasil, durante as estações chuvosa e seca, foram obtidos por hidrodestilação e analisados por GC-MS. Os principais compostos identificados foram 2-tridecanona, beta-cariofileno, 2-pentadecanona, óxido de cariofileno e germacreno D. Seus teores percentuais variam com a estação, embora os maiores valores tenham sido detectados principalmente na estação chuvosa. Para 2-tridecanona e beta-cariofileno os valores mais expressivos foram observados nos óleos de galhos finos, para o primeiro, e nos óleos das folhas, para o útimo. Para 2-pentadecanona, óxido de cariofileno e germacreno D, os valores mais altos foram, também, nos óleos das folhas. Em geral, os óleos das folhas se apresentaram muito distintos em relação aos galhos finos, assim como também no mesmo espécime.

  19. Seasonal Variations in Dust Loading within Gale Crater, Mars

    Science.gov (United States)

    Moore, Casey; Moores, John; Smith, Christina L.; MSL Science Team

    2016-10-01

    The Mars Science Laboratory rover Curiosity has been exploring Gale Crater for more than two martian years. Such tenure allows seasonal variability of the weather record for the current era to be studied with aid from Mast Cameras (Mastcam), Navigation Cameras (Navcam) and Rover Environmental Monitoring Station (REMS). Dust is a key component in the Martian atmosphere which helps drive atmospheric circulation. As such, these three instruments are integral in the characterization of the dust-loading environment both within and above the crater. This study uses Navcam imagery and a digital terrain model provided from HRSC on Mars Express to derive geographical line-of-sight extinction (LOS-Ext) coefficients, a quantity that assesses dust loading local to the air within the crater and which reveals differences in dust loading along different lines of sight.We report two martian years worth of LOS-Ext at Gale Crater, covering Ls 210° in Mars year (MY) 31 to Ls 210° in MY33. All seasons have been observed twice with the only significant exception being a gap in data between Ls 270° - 315° in MY31 (early southern summer). Visibility conditions within the crater range from a few tens of km in spring and summer to over 100 km peaking around the winter solstice. The LOS-Ext record is also compared to the column extinction record derived from the Mastcam Tau observations. The first year shows a convergence of the two values around Ls 270° in MY31 and similar values around Ls 350° in MY31 and Ls 135° in MY32. Otherwise, during the first year of observation, the LOS-Ext has lower values than the Mastcam column extinction indicating two non-interacting atmospheric layers. In the second year, not only are similar values observed more frequently, the LOS-Ext coefficients have a global peak and overtake Mastcam column extinction during Ls 270° - 315° in MY32, which correspond to the missing timeframe from the previous year. As this season is prone to high wind speeds

  20. Seasonal bacterial community dynamics in a full-scale enhanced biological phosphorus removal plant.

    Science.gov (United States)

    Flowers, Jason J; Cadkin, Tracey A; McMahon, Katherine D

    2013-12-01

    Activated sludge is one of the most abundant and effective wastewater treatment process used to treat wastewater, and has been used in developed countries for nearly a century. In all that time, several hundreds of studies have explored the bacterial communities responsible for treatment, but most studies were based on a handful of samples and did not consider temporal dynamics. In this study, we used the DNA fingerprinting technique called automated ribosomal intergenic spacer region analysis (ARISA) to study bacterial community dynamics over a two-year period in two different treatment trains. We also used quantitative PCR to measure the variation of five phylogenetically-defined clades within the Accumulibacter lineage, which is a model polyphosphate accumulating organism. The total bacterial community exhibited seasonal patterns of change reminiscent of those observed in lakes and oceans. Surprisingly, all five Accumulibacter clades were present throughout the study, and the total Accumulibacter community was relatively stable. However, the abundance of each clade did fluctuate through time. Clade IIA dynamics correlated positively with temperature (ρ = 0.65, p < 0.05) while Clade IA dynamics correlated negatively with temperature (ρ = -0.35, p < 0.05). This relationship with temperature hints at the mechanisms that may be driving the seasonal patterns in overall bacterial community dynamics and provides further evidence for ecological differentiation among clades within the Accumulibacter lineage. This work provides a valuable baseline for activated sludge bacterial community variation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Seasonal Variation in Water Quality of Lukha River, Meghalaya, India

    Directory of Open Access Journals (Sweden)

    R. Eugene Lamare

    2016-04-01

    Full Text Available Lukha River (Wah Lukha is one of the major rivers of Meghalaya situated in the southern part of East Jaintia Hills District. Activities such as mining of coal and limestone, manufacturing of cement, deforestation etc. have been taking place in the catchment area of the river leading to changes in water quality. This is evident from the deep blue appearance of water of Lukha River during winter months for the last 7-8 years.Till date no convincing and conclusive reason has been given for this annual change in physical appearance.To get insight, we studied the physico-chemical water quality parameters of this river in different seasons and found that the water quality has started deteriorating due to activities occurring in the catchment area. Based on Canadian Council of Ministers of the Environment-Water Quality Index (CCME-WQI the water of the river at some locations was found of ‘poor’ quality.

  2. Longitudinal and Seasonal Variation of Lunar tide strength

    Science.gov (United States)

    Yizengaw, E.; Pacheco, E. E.; Valladares, C. E.

    2012-12-01

    It has been known since many decades that lunar tide, which manifests itself as a semi-diurnal wave that precesses through all local times within one lunar month, has been identified as a significant force that can produce a notable influence on the longitudinal equatorial density distribution and equatorial electrojet (EEJ). However, there has never been a comprehensive study, except some statistical analysis using the satellite based in-situ observations, of the lunar tide effect on a global scale. This left several questions, like the longitudinal and solar flux dependence of the lunar tide, the tidal wave strength difference between new and full moon phases, remained unanswered. The proximity of the Earth/Moon system to the Sun, proximity of a New/Full Moon to one of the nodes of the lunar orbit, and the proximity of a New/Full Moon to the perigee of the lunar orbit are among the main factors that can affect the seasonal variability of lunar tide strength. With the indications of lunar tide influence on the strength of dayside EEJ, enhancing EEJ's strength shortly after new and full moon, we utilize the ground-based magnetometer fourteen years (1998 - 2012) data and investigate the various aspects of lunar tide effects on the EEJ at three different longitudinal sectors. The equatorial magnetometers located at Jicamarca for American sector, Addis Ababa for African sector, and Tirunelveli for Indian sector are used for this comprehensive study. Simultaneously, using the GPS TEC data, we examined the lunar tide impacts on the equatorial density irregularities and bubble formations at different longitudinal sectors. We found surprising strong longitudinal dependence in the lunar tide strength and its influence on EEJ and density bubble formation. Significant solar flux and seasonal dependences in lunar tide strength have also been observed at all longitudinal sectors. Finally, we investigated the lunar tide strength difference between new moon and full moon phases.

  3. Seasonal and population variation in male testosterone levels in breeding orange-crowned warblers (Vermivora celata).

    Science.gov (United States)

    Horton, Brent M; Yoon, Jongmin; Ghalambor, Cameron K; Moore, Ignacio T; Scott Sillett, T

    2010-09-15

    Comparative hormone studies can reveal how physiology underlies life history variation. Here, we examined seasonal variation in plasma testosterone concentration between populations of male orange-crowned warblers (Vermivora celata) breeding in Fairbanks, Alaska (V. c. celata) and on Santa Catalina Island, California (V. c. sordida). These populations face different ecological constraints and exhibit different life histories. Alaska birds have a short breeding season, low annual adult survival, and high reproductive rates. In contrast, Catalina Island birds exhibit high adult survival and low reproductive rates despite having a long breeding season. We examined seasonal variation in male testosterone concentrations as a potential mechanism underlying differences in male reproductive strategies between populations. From 2006 to 2008, we sampled males during the pre-incubation, incubation, and nestling stages. Alaska males exhibited a seasonal testosterone pattern typical of northern passerines: testosterone levels were high during pre-incubation and declined during incubation to low levels during nestling provisioning. Testosterone concentrations in Catalina Island males, however, did not vary consistently with breeding stage, remained elevated throughout the breeding season, and were higher than in Alaska males during the nestling stage. We hypothesize that in Alaska, where short seasons and high adult mortality limit breeding opportunities, the seasonal testosterone pattern facilitates high mating effort prior to incubation, but high parental investment during the nestling stage. On Catalina Island, elevated testosterone levels may reflect the extended mating opportunities and high population density facing males in this population. Our results suggest that population variation in seasonal testosterone patterns in orange-crowned warblers may be a function of differences in life history strategy and the social environment.

  4. Seasonal Gravity Field Variations from GRACE and Hydrological Models

    DEFF Research Database (Denmark)

    Andersen, Ole Baltazar; Hinderer, Jacques; Lemoine, Frank G.

    2004-01-01

    This study present an investigation of the newly released 18 monthly gravity field solutions from the GRACE twin space-crafts with emphasis on the global scale annual gravity field variations observed from GRACE and modeled from hydrological models as annual changes in terrestrial water storage....... Four global hydrological models covering the same period in 2002–2003 as the GRACE observations were investigated to for their mutual consistency in estimates of annual variation in terrestrial water storage and related temporal changes in gravity field. The hydrological models differ by a maximum of 2...... µGal or nearly 5 cm equivalent water storage in selected regions. Integrated over all land masses the standard deviation among the annual signal from the four hydrological models are 0.6 µGal equivalent to around 1.4 cm in equivalent water layer thickness. The estimated accuracy of the annual...

  5. Seasonal variations of group-specific phytoplankton cell death in Xiamen Bay, China

    Science.gov (United States)

    Huang, Xiaozhou; Liu, Xin; Chen, Jixin; Xiao, Wupeng; Cao, Zhen; Huang, Bangqin

    2017-03-01

    The importance of phytoplankton cell death is being increasingly recognized, however, there are still no published reports on this in Xiamen Bay. In this study, the proportion of dead phytoplankton cells associated with environmental factors was assessed at a station in Xiamen Bay from December 2012 to December 2013, using a cell digestion assay, which is an effective method to analyze dead/ living cells in complex natural phytoplankton communities. The percentages of dead cells (% DC) in the total phytoplankton in summer (16%±6%) were lower than those in winter (27%±16%). Six groups of phytoplankton (G1-G6) were categorized by flow cytometry. These phytoplankton communities with diverse seasonal variations in % DC had different responses to environmental constraints. The main factors affecting mortality were temperature and salinity, while nutrient concentration showed little influence on phytoplankton death. Additionally, our results provide evidence that chlorophyll a concentrations had an inverse relationship with total phytoplankton % DC and viable cell abundance was more meaningful than total cells to explain variations in environmental parameters (such as Chl a). Moreover, the lowest mean % DC in total phytoplankton was 16%±6% at our sample site, which is in a subtropical area with high water temperatures, full solar radiation, and rich nutrients. This indicates that phytoplankton cell death is a process that cannot be ignored. In summary, phytoplankton cell death is important in understanding the dynamics of phytoplankton communities and the functioning of subtropical ecosystems.

  6. Length of activity season drives geographic variation in body size of a widely distributed lizard

    OpenAIRE

    Horváthová, Terézia; Cooney, Christopher R.; Fitze, Patrick S; Oksanen, Tuula; Jelic, Dusan; Ghira, Ioan; Uller, Tobias; Jandzik, David

    2013-01-01

    Understanding the factors that drive geographic variation in life history is an important challenge in evolutionary ecology. Here, we analyze what predicts geographic variation in life-history traits of the common lizard, Zootoca vivipara, which has the globally largest distribution range of all terrestrial reptile species. Variation in body size was predicted by differences in the length of activity season, while we found no effects of environmental temperature per se. Females experiencing r...

  7. Dynamical forcing of sub-seasonal variability in the tropical Brewer-Dobson circulation

    Science.gov (United States)

    Abalos, Marta; Randel, William; Serrano, Encarna

    2014-05-01

    Upwelling across the tropical tropopause exhibits strong sub-seasonal variability superimposed on the well-known annual cycle, and these variations directly affect temperature and tracers in the tropical lower stratosphere. The dynamical forcing of tropical upwelling on sub-seasonal timescales is investigated using the ERA-Interim reanalysis for 1979-2011. Momentum balance diagnostics reveal that transience is linked to the effects of extratropical wave forcing, with centers of action in the extratropical winter stratosphere and in the subtropical upper troposphere of both hemispheres. From a diagnostic point of view, the zonal-mean wind transient response is important for communicating the remote wave forcing to the tropical stratosphere. Dynamical patterns reflect distinctive forcing of the shallow versus deep branches of the Brewer-Dobson circulation.

  8. Seasonal variations of air-sea heat fluxes and sea surface temperature in the northwestern Pacific marginal seas

    Institute of Scientific and Technical Information of China (English)

    LIU Na; WU Dexing; LIN Xiaopei; MENG Qingjia

    2014-01-01

    Using a net surface heat flux (Qnet) product obtained from the objectively analyzed air-sea fluxes (OAFlux) project and the international satellite cloud climatology project (ISCCP), and temperature from the simple ocean data assimilation (SODA), the seasonal variations of the air-sea heat fluxes in the northwestern Pa-cific marginal seas (NPMS) and their roles in sea surface temperature (SST) seasonality are studied. The seasonal variations of Qnet, which is generally determined by the seasonal cycle of latent heat flux (LH), are in response to the advection-induced changes of SST over the Kuroshio and its extension. Two dynamic regimes are identified in the NPMS:one is the area along the Kuroshio and its extension, and the other is the area outside the Kuroshio. The oceanic thermal advection dominates the variations of SST and hence the sea-air humidity plays a primary role and explains the maximum heat losing along the Kuroshio. The heat transported by the Kuroshio leads to a longer period of heat losing over the Kuroshio and its Extension. Positive anomaly of heat content corresponds with the maximum heat loss along the Kuroshio. The oceanic advection controls the variations of heat content and hence the surface heat flux. This study will help us understand the mechanism controlling variations of the coupled ocean-atmosphere system in the NPMS. In the Kuroshio region, the ocean current controls the ocean temperature along the main stream of the Ku-roshio, and at the same time, forces the air-sea fluxes.

  9. Seasonal variation of residence time in spring and groundwater evaluated by CFCs and numerical simulation in mountainous headwater catchment

    Science.gov (United States)

    Tsujimura, Maki; Watanabe, Yasuto; Ikeda, Koichi; Yano, Shinjiro; Abe, Yutaka

    2016-04-01

    Headwater catchments in mountainous region are the most important recharge area for surface and subsurface waters, additionally time information of the water is principal to understand hydrological processes in the catchments. However, there have been few researches to evaluate variation of residence time of subsurface water in time and space at the mountainous headwaters especially with steep slope. We investigated the temporal variation of the residence time of the spring and groundwater with tracing of hydrological flow processes in mountainous catchments underlain by granite, Yamanashi Prefecture, central Japan. We conducted intensive hydrological monitoring and water sampling of spring, stream and ground waters in high-flow and low-flow seasons from 2008 through 2013 in River Jingu Watershed underlain by granite, with an area of approximately 15 km2 and elevation ranging from 950 m to 2000 m. The CFCs, stable isotopic ratios of oxygen-18 and deuterium, inorganic solute constituent concentrations were determined on all water samples. Also, a numerical simulation was conducted to reproduce of the average residence times of the spring and groundwater. The residence time of the spring water estimated by the CFCs concentration ranged from 10 years to 60 years in space within the watershed, and it was higher (older) during the low flow season and lower (younger) during the high flow season. We tried to reproduce the seasonal change of the residence time in the spring water by numerical simulation, and the calculated residence time of the spring water and discharge of the stream agreed well with the observed values. The groundwater level was higher during the high flow season and the groundwater dominantly flowed through the weathered granite with higher permeability, whereas that was lower during the low flow season and that flowed dominantly through the fresh granite with lower permeability. This caused the seasonal variation of the residence time of the spring

  10. Seasonal variations of arsenic in mussels Mytilus galloprovincialis

    Science.gov (United States)

    Klarić, Sanja; Pavičić-Hamer, Dijana; Lucu, Čedomil

    2004-10-01

    Total arsenic concentration in the edible part of mussels Mytilus galloprovincialis was evaluated seasonally in the coastal area of Rijeka Bay (North Adriatic Sea, Croatia). Sampling stations were located close to the City of Bakar with no industrial facilities (site 1), in the vicinity of the oil refinery and oil thermoelectric power plant (Urinj, site 2), and 4 miles away from the Plomin coal thermoelectric power plant (Brseč village, site 3). Additionally, the concentration of arsenic in the tail muscle of the lobster Nephrops norvegicus, collected in Rijeka Bay, was studied. During winter at sites 2 and 3, the total arsenic in the edible part of the mussels was 16.4 mg As/kg FW (FW=fresh weight) and 4.38 mg As/kg FW, respectively, and increased during springtime at site 2 (6.5 mg As/kg FW) compared to the rest of the year, when individual total arsenic concentration at all sites ranged from 1.7 to 3.7 mg As/kg FW. In the winter (sites 2 and 3) and springtime (site 2) there was no correlation between the length of the mussel shell and the arsenic concentration in the edible part of the mussels. In the other seasons, at sites 1, 2 and 3, there was a correlation between arsenic in the edible part of mussels and shell length in most cases (correlation coefficients r varied from 0.64 to 0.85; P <0.05 to P <0.01). Correlation between shell length (in the narrow range of shell lengths from 3.4 to 5.0 cm) and arsenic in the edible part of the mussels shows linearity with a high regression coefficient (r =0.914; P <0.001). The increase of arsenic in the mussels during winter and spring was suggested at least partially as a result of a low nutritional status, i.e. reduced weight of the mussels' edible part during winter. In addition, a linear relationship was found between body length and arsenic concentration in the tail muscle (mean 17.11±4.48 mg As/kg FW) of the Norway lobster.

  11. Seasonal variation in toxicity of citral against Fasciola larva

    Institute of Scientific and Technical Information of China (English)

    Kumari Sunita; Pradeep Kumar; Dinesh Kumar Singh

    2014-01-01

    Objective:To test whether the larvicidal activity of citral against Fasciola varies by season. Methods:Mortality of Fasciola larva in different month of year (2011-2012) in in vitro and in vivo condition were observed at 2 h, 4 h, 6 h and 8 h exposure of citral. Results:In vitro toxicity of citral against redia was highest in between the June to August (8 h LC50: 2.58-2.62 mg/L), whereas against cercaria 8 h LC50 was in between 3.44-2.62 mg/L. Highest in vivo toxicity against redia was noted in between June to August (8h LC50: 4.20-5.09 mg/L). The lowest toxicity was observed from November to April. The highest temperature, free carbon dioxide, and lowest pH, dissolved oxygen were observed from June to August. Conclusions:The present study conclusively shows that varying a biotic factor can significantly alter the in vitro and in vivo toxicity of citral against sporocyst redia and cercaria larva.

  12. Seasonal and Spatial Variations of Indoor Pollen in a Hospital

    Directory of Open Access Journals (Sweden)

    Santiago Fernández-Rodríguez

    2009-12-01

    Full Text Available The airborne indoor pollen in a hospital of Badajoz (Spain was monitored over two years using a personal Burkard sampler. The air was sampled in four places indoors—one closed room and one open ward on each of the ground and the third floors—and one place outdoors at the entrance to the hospital. The results were compared with data from a continuous volumetric sampler. While 32 pollen types were identified, nearly 75% of the total counts were represented by just five of them. These were: Quercus, Cupressaceae, Poaceae, Olea, and Plantago. The average indoor concentration was 25.2 grains/m3, and the average indoor/outdoor ratio was 0.27. A strong seasonal pattern was found, with the highest levels in spring and winter, and the indoor concentrations were correlated with the outdoor one. Indoor air movement led to great homogeneity in the airborne pollen presence: the indoor results were not influenced by whether or not the room was isolated, the floor level, or the number of people in or transiting the site during sampling. The presence of ornamental vegetation in the area surrounding the building affected the indoor counts directly as sources of the pollen.

  13. An investigation of the potential causes for the seasonal and annual variations in indoor radon concentrations.

    Science.gov (United States)

    Barazza, F; Gfeller, W; Palacios, M; Murith, C

    2015-11-01

    Indoor radon concentrations exhibit strong variations on short and long timescales. Besides human influences, meteorological factors significantly affect the radon concentrations indoors as well as outdoors. In this article, long-term measurements showing strong annual variations are presented, which take a very similar course in different buildings located in largely separated regions in Switzerland. Also, seasonal variations can be very significant. In general, variations in indoor radon levels can primarily be attributed to human influences. On the other hand, specific weather conditions can have a significant impact on indoor radon levels. In order to further investigate the connection between indoor radon levels and meteorological factors, a measuring campaign has been started in two buildings located in two different regions in Switzerland exhibiting different climatic characteristics. Preliminary results of these investigations are presented, which provide evidence for correlations between indoor radon levels and in particular outdoor temperatures, contributing to seasonal and annual as well as short-term variations in indoor radon concentrations.

  14. Seasonal effect on the diurnal variation of the geomagnetic field registered in Huancayo Observatory

    CERN Document Server

    Rosales, Domingo

    2016-01-01

    In this article we study the seasonal effect on the diurnal variation of the geomagnetic field registered in the Huancayo Observatory, located in the Magnetic Equator, which is driven by "ionospheric currents" and its counterpart induced by "telluric currents". Huancayo Observatory has the highest amplitude in the diurnal variation, because of being in the Magnetic Equator and under the "Equatorial Electrojet". We present the pattern of seasonal variation in diurnal variation of components X, Y and Z, the same as confirmed by previous works since 1940. The effect of solar activity cycle of about 11 years in the diurnal variation is also confirmed; it is observed that amplitudes are greater in the maximum of solar activity.

  15. Seasonal and Interdecadal Variations of Heat Transport over the Northern Hemisphere

    Institute of Scientific and Technical Information of China (English)

    SUN Jilin; XU Delong; GU Dejun

    2006-01-01

    Using NCEP/NCAR reanalysis data, variations of heat transport in the Northern Hemisphere were studied.It was found that there are interdecadal variations in heat transport from middle latitudes to higher latitudes.The variations of interdecadal heat transport over longitudes around 120°E are out of phase with those over around 90°E and over the Northeastern Pacific.The seasonal variations of heat transport were also discussed.It was found that most heat is transported in the lower layer of the troposphere from middle latitudes to higher latitudes.Over around 120°E and over around 120°W, the seasonal and interannual variations of heat transport across 32.5°N are apparent and in phase.

  16. Did Knut Hamsun suffer from seasonal variation in mood? : A prospective study.

    OpenAIRE

    2004-01-01

    Background: Studies on creativity and mental illness and reports on Seasonal Affective Disorder in artist often have methodological weaknesses; in particular they tend to be retrospective. Knut Hamsun was an original writer and Nobel Prize winner in literature. Anecdotes from his life suggest that he suffered from SAD. Prospective methods were used to investigate if Hamsun revealed seasonal variations in mood. Methods: 3318 of Hamsuns’s letters are published and stored electronically in...

  17. Study of Seasonal Variation in Groundwater Quality of Sagar City (India) by Principal Component Analysis

    OpenAIRE

    Hemant Pathak; S. N. Limaye

    2011-01-01

    Groundwater is one of the major resources of the drinking water in Sagar city (India.). In this study 15 sampling station were selected for the investigations on 14 chemical parameters. The work was carried out during different months of the pre-monsoon, monsoon and post-monsoon seasons in June 2009 to June 2010. The multivariate statistics such as principal component and cluster analysis were applied to the datasets to investigate seasonal variations in groundwater quality. Principal axis fa...

  18. Speciation of selenium in groundwater: Seasonal variations and redox transformations

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A. Ramesh [Chemical Laboratory, Central Groundwater Board, South Eastern Coastal Region, E1, Rajaji Bhavan, Besant Nagar, Chennai 600 090 (India); Riyazuddin, P., E-mail: riyazdr@yahoo.co.uk [Department of Analytical Chemistry, University of Madras, Guindy Campus, Chennai 600 025, Tamil Nadu (India)

    2011-08-15

    Highlights: {yields} Selenium(VI) was the predominant species of Se present in groundwater. {yields} Groundwater recharge increased Se mobilization. {yields} Dissolved oxygen and redox potential control the mobilization of soil selenium. {yields} Shallow groundwater is susceptible for more selenium enrichment than deeper ones. - Abstract: Speciation of selenium in groundwater is essential from the viewpoint of toxicity to organisms and biogeochemical cycling. Selenium speciation in groundwater is controlled by aquifer redox conditions, microbial transformations, dissolved oxygen (DO) and other redox couples. A suburban area of Chennai city in India, where improper waste disposal measures have been practiced is selected for this study. Se(IV), Se(VI) and other hydrochemical parameters were monitored in shallow ground water during pre- and post-monsoon seasons for a period of three years. The objective of the study was to investigate the effect of groundwater recharge on selenium speciation. The concentration of Se(IV), and Se(VI) ranged between 0.15-0.43 {mu}g L{sup -1} and 0.16-4.73 {mu}g L{sup -1}, respectively. During post-monsoon period the concentration of Se(IV), and Se(VI) ranged between 0.15-1.25 {mu}g L{sup -1} and 0.58-10.37 {mu}g L{sup -1}, respectively. Se(VI) was the dominant species of selenium during the pre- and post-monsoon periods. During the post-monsoon periods, leaching of selenium from soil was more effective due to the increased oxidizing nature of the groundwater as indicated by the DO and redox potential (Eh) measurements. This finding has important implications on the behavior of selenium in groundwater, and also on the health of people consuming groundwater from seleniferous areas.

  19. Seasonal variation of daily physical activity in individuals with heart failure

    Directory of Open Access Journals (Sweden)

    Michael J. Shoemaker

    2016-09-01

    Full Text Available Background Previous studies indicate that seasonal variation affects daily physical activity (PA, but none have investigated this relationship in individuals with heart failure (HF who also have implanted cardioverter defibrillators and cardiac resynchronization therapy (ICD/CRT devices. The purpose of the present study was to determine if seasonal variation in temperature affects daily PA in patients with HF and ICD/CRTs. Patients and methods Secondary analysis of data from 16 subjects with HF and Medtronic® ICD/CRT devices enrolled in a randomized trial investigating interventions to improve daily PA. Due to the rolling study enrollment, daily PA data for all subjects were not available for the entire time frame and were divided into two groups. Determination of seasonal variation of daily PA was determined using visual analysis of daily PA plotted with average temperature, autocorrelation, visual analysis of seasonal subseries plots and boxplot analysis, as well as Wilcoxon signed-rank tests. Results Subjects 1-8 demonstrated the greatest differences in daily PA during periods of seasonal transition whereas subjects 9-16 demonstrated the greatest variation in daily PA with greatest seasonal temperature difference. Wilcoxon signed-rank testing of the lowest and highest months for daily PA revealed median differences of 0.30 (p = 0.050 and 0.36 hours (p = 0.036 for subjects 1-8 and 9-16, with effect sizes of 0.69 and 0.74, respectively. Conclusions Seasonal variation in mean temperature appears to affect daily PA in individuals with HF and ICD/CRT devices by a magnitude of 0.30-0.36 hours, which may need to be accounted for in future research investigating interventions to improve daily PA.

  20. Seasonal variation of surface fluxes and atmospheric interaction in Istanbul

    Energy Technology Data Exchange (ETDEWEB)

    Aslan, Z.; Topcu, S. [Istanbul Technical Univ. (Turkey)

    1994-12-31

    A central objective of micrometeorological research is to establish fluxes from a knowledge of the mean temperature, humidity and wind speed profiles. The effect of time and spatial variations of surface heat and momentum fluxes is studied for various geographic regions. These analysis show the principal boundary conditions for micro and meso-scale analysis, air-sea interactions, weather forecasting air pollution, agrometeorology and climate changing models. The fluxes of heat and momentum can be obtained from observed profiles of wind speed and temperature using the similarity relations for the atmospheric surface layer. In recent years, harmonic analysis is a particularly useful tool in studying annual patterns of some meteorological parameters at the field of micrometeorological studies.

  1. Impact factors on fine root seasonal dynamics in Fraxinus mandshurica plantations

    Institute of Scientific and Technical Information of China (English)

    MEI Li; HAN Youzhi; YU Shuiqiang; SHI Jianwei; WANG Zhengquan

    2007-01-01

    Fine root turnover plays important roles in carbon allocation and nutrient cycling in forest ecosystems.Seasonal dynamics of fine roots is critical for understanding the processes of fine root turnover.From May to October 2002,soil core method was used for estimating the seasonal pattern of fine root (diameter < 1 mm) parameters (biomass,specific root length (SRL) and root length density (RLD)) in a Manchurian ash (Fraxinus mandshurica) plantation located at the Maoershan Experiment Station,Heilongjiang Province,northeast of China.The relationships of fine root biomass,SRL and RLD with available nitrogen in soil,average soil temperature per month in 10 cm depth and soil moisture content were analyzed.Seasonal variation of fine root biomass was significant (P < 0.05).The peak values of fine root biomass were observed both in spring and in autumn,but SRL and RLD were the highest in spring and lowest in autumn.Specific root length and root length density were higher in spring and summer,which means that fine root diameter was thinner.In autumn,both parameters decreased significantly due to secondary incrassation of fine root diameter or the increase of tissue density.Seasonal dynamics of fine roots was associated with available nitrogen in soil,soil temperature in 10 cm depth and moisture content.Fine root biomass has a significant relationship with available NH4+-N in soil.Available NO3--N in soil,soil temperature in 10-cm depth and moisture content have a positive correlation with fine root biomass,SRL and RLD,although these correlations are not significant (P >0.05).But the compound effects of soil available N,soil temperature and soil moisture content are significant to every root parameter.The variations of these three root parameters in different seasons show different physiological and ecological functions in different growing periods.

  2. Cesarean delivery in preeclampsia and seasonal variation in a tropical rainforest belt

    Directory of Open Access Journals (Sweden)

    Okafor U

    2010-01-01

    Full Text Available Background: The pathogenesis of preeclampsia is poorly understood and recent evidence suggests that the incidence varies depending upon the season. Aim: This study was carried out to determine whether there is a seasonal variation in the presentation of preeclamptics undergoing cesarean delivery in a tropical rainforest belt. Setting: A university teaching hospital. Study Design: Retrospective. Materials and Methods: The hospital records of consecutive patients (July 1996-June 2006 with preeclampsia, who underwent cesarean delivery in a tertiary care centre, were reviewed. Data collected included patient demographics, total number of deliveries, number of cesarean deliveries, and number of preeclampsia patients and time of presentation for cesarean section. Approval of the local ethical committee was obtained. Statistical Analysis: The EPI info software program was used for statistical analysis. Results: A total of 6798 deliveries were recorded during the study period resulting in 6485 live births. There were 1579 cesarean deliveries during the period. Of these, 196 patients had toxemia of pregnancy (166 with preeclampsia and 30 with eclampsia. One hundred and forty-one patients (9% of cesarean deliveries had cesarean delivery during the rainy season and 55 (3.5% during the dry season (P < 0.05. Amongst preeclampsia patients, 115 presented (7% during the rainy season and 51 (3.2% during the dry season (P < 0.05. In the eclampsia group, 26 (1.65% of cesarean sections presented during the rainy season and four (0.25% during the dry season (P < 0.05. Conclusions: There was a seasonal variation in the cesarean delivery required for preeclampsia/eclampsia patients. This may help in counseling women on when to plan their pregnancy in order to reduce the morbidity and mortality associated with this apparent seasonal disease.

  3. Genetic and phenotypically flexible components of seasonal variation in immune function.

    Science.gov (United States)

    Versteegh, M A; Helm, B; Kleynhans, E J; Gwinner, E; Tieleman, B I

    2014-05-01

    Animals cope with seasonal variation in environmental factors by adjustments of physiology and life history. When seasonal variation is partly predictable, such adjustments can be based on a genetic component or be phenotypically flexible. Animals have to allocate limited resources over different demands, including immune function. Accordingly, immune traits could change seasonally, and such changes could have a genetic component that differs between environments. We tested this hypothesis in genotypically distinct groups of a widespread songbird, the stonechat (Saxicola torquata). We compared variation in immunity during 1 year in long-distance migrants, short-distance migrants, tropical residents and hybrids in a common garden environment. Additionally, we investigated phenotypically flexible responses to temperature by applying different temperature regimes to one group. We assessed constitutive immunity by measuring hemagglutination, hemolysis, haptoglobin and bactericidal ability against Escherichia coli and Staphylococcus aureus. Genotypic groups differed in patterns of variation of all measured immune indices except haptoglobin. Hybrids differed from, but were rarely intermediate to, parental subspecies. Temperature treatment only influenced patterns of hemolysis and bactericidal ability against E. coli. We conclude that seasonal variation in constitutive immunity has a genetic component, that heredity does not follow simple Mendelian rules, and that some immune measures are relatively rigid while others are more flexible. Furthermore, our results support the idea that seasonal variability in constitutive immunity is associated with variability in environment and annual-cycle demands. This study stresses the importance of considering seasonal variation in immune function in relation to the ecology and life history of the organism of interest.

  4. Seasonal variations of gonadotropins and prolactin in the laboratory rat. Role of maternal pineal gland.

    Science.gov (United States)

    Vázquez, N; Díaz, E; Fernández, C; Jiménez, V; Esquifino, A; Díaz, B

    2007-01-01

    The laboratory rat, a non-photoperiodic rodent, exhibits seasonal fluctuations of melatonin. Melatonin has been found to be readily transferred from the maternal to the fetal circulation. No data exist on the possible influence of maternal pineal gland upon seasonal variations of the offspring. The aim of the present study was to asses the influence of the maternal melatonin rhythm on the offspring postnatal development of the reproductive hormones LH, FSH and prolactin. Male offspring from control, pinealectomized (PIN-X) and PIN-X + melatonin (PIN-X+MEL) mother Wistar rats were studied at 21, 31, and 60 days of age. Seasonal age-dependent variations were found for all hormones studied in control offspring but PIN-X offspring showed a tendency to have reduced duration or altered seasonal variations. Maternal melatonin treatment to PIN-X mothers partially restored the effect of pinealectomy. The chronological study of LH, FSH, and prolactin in PIN-X offspring also showed an altered pattern as compared to control-offspring. Melatonin treatment to the mothers partially restored the developmental pattern of reproductive hormones. Results of this study indicate that maternal pineal gland of the laboratory rat is involved in the seasonal postnatal development variations of reproductive hormones of the offspring.

  5. Seasonal Variations of Mercury's Magnesium Dayside Exosphere from MESSENGER Observations

    Science.gov (United States)

    Merkel, Aimee W.; Cassidy, Timothy A.; Vervack, Ronald J., Jr.; McClintock, William E.; Sarantos, Menelaos; Burger, Matthew H.; Killen, Rosemary M.

    2017-01-01

    The Ultraviolet and Visible Spectrometer channel of the Mercury Atmospheric and Surface Composition Spectrometer instrument aboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft made near-daily observations of solar-scattered resonant emission from magnesium in Mercury's exosphere during the mission's orbital phase (March 2011-April 2015, approx.17 Mercury years). In this paper, a subset of these data (March 2013-April 2015) is described and analyzed to illustrate Mg's spatial and temporal variations. Dayside altitude profiles of emission are used to make estimates of the Mg density and temperature. The main characteristics of the Mg exosphere are (a) a predominant enhancement of emission in the morning (6 am-10 am) near perihelion, (b) a bulk temperature of approx. 6000 K, consistent with impact vaporization as the predominant ejection process, (c) a near-surface density that varies from 5/cu cm to 50/cu cm and (d) a production rate that is strongest in the morning on the inbound leg of Mercury's orbit with rates ranging from 1×10(exp 5)/sq cm/s to 8×10(exp 5)/sq cm/s.

  6. Seasonal Variations of Mercury's Magnesium Dayside Exosphere from MESSENGER Observations

    Science.gov (United States)

    Merkel, Aimee W.; Cassidy, Timothy A.; Vervack, Ronald J., Jr.; McClintock, William E.; Sarantos, Menelaos; Burger, Matthew H.; Killen, Rosemary M.

    2017-01-01

    The Ultraviolet and Visible Spectrometer channel of the Mercury Atmospheric and Surface Composition Spectrometer instrument aboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft made near-daily observations of solar-scattered resonant emission from magnesium in Mercury's exosphere during the mission's orbital phase (March 2011-April 2015, approx.17 Mercury years). In this paper, a subset of these data (March 2013-April 2015) is described and analyzed to illustrate Mg's spatial and temporal variations. Dayside altitude profiles of emission are used to make estimates of the Mg density and temperature. The main characteristics of the Mg exosphere are (a) a predominant enhancement of emission in the morning (6 am-10 am) near perihelion, (b) a bulk temperature of approx. 6000 K, consistent with impact vaporization as the predominant ejection process, (c) a near-surface density that varies from 5/cu cm to 50/cu cm and (d) a production rate that is strongest in the morning on the inbound leg of Mercury's orbit with rates ranging from 1×10(exp 5)/sq cm/s to 8×10(exp 5)/sq cm/s.

  7. Seasonal variations of Mercury's magnesium dayside exosphere from MESSENGER observations

    Science.gov (United States)

    Merkel, Aimee W.; Cassidy, Timothy A.; Vervack, Ronald J.; McClintock, William E.; Sarantos, Menelaos; Burger, Matthew H.; Killen, Rosemary M.

    2017-01-01

    The Ultraviolet and Visible Spectrometer channel of the Mercury Atmospheric and Surface Composition Spectrometer instrument aboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft made near-daily observations of solar-scattered resonant emission from magnesium in Mercury's exosphere during the mission's orbital phase (March 2011-April 2015, ∼17 Mercury years). In this paper, a subset of these data (March 2013-April 2015) is described and analyzed to illustrate Mg's spatial and temporal variations. Dayside altitude profiles of emission are used to make estimates of the Mg density and temperature. The main characteristics of the Mg exosphere are (a) a predominant enhancement of emission in the morning (6 am-10 am) near perihelion, (b) a bulk temperature of ∼6000 K, consistent with impact vaporization as the predominant ejection process, (c) a near-surface density that varies from 5 cm-3 to 50 cm-3 and (d) a production rate that is strongest in the morning on the inbound leg of Mercury's orbit with rates ranging from 1 × 105 cm-2 s-1 to 8 × 105 cm-2 s-1.

  8. Seasonal variations in virus-host populations in Norwegian coastal waters: focusing on the cyanophage community infecting marine Synechococcus spp.

    Science.gov (United States)

    Sandaa, Ruth-Anne; Larsen, Aud

    2006-07-01

    Viruses are ubiquitous components of the marine ecosystem. In the current study we investigated seasonal variations in the viral community in Norwegian coastal waters by pulsed-field gel electrophoresis (PFGE). The results demonstrated that the viral community was diverse, displaying dynamic seasonal variation, and that viral populations of 29 different sizes in the range from 26 to 500 kb were present. Virus populations from 260 to 500 kb and dominating autotrophic pico- and nanoeukaryotes showed similar dynamic variations. Using flow cytometry and real-time PCR, we focused in particular on one host-virus system: Synechococcus spp. and cyanophages. The two groups covaried throughout the year and were found in the highest amounts in fall with concentrations of 7.3 x 10(4) Synechococcus cells ml(-1) and 7.2 x 10(3) cyanophage ml(-1). By using primers targeting the g20 gene in PCRs on DNA extracted from PFGE bands, we demonstrated that cyanophages were found in a genomic size range of 26 to 380 kb. The genetic richness of the cyanophage community, determined by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified g20 gene fragments, revealed seasonal shifts in the populations, with one community dominating in spring and summer and a different one dominating in fall. Phylogenetic analysis of the sequences originating from PFGE and DGGE bands grouped the sequences into three groups, all with homology to cyanomyoviruses present in cultures. Our results show that the cyanophage community in Norwegian coastal waters is dynamic and genetically diverse and has a surprisingly wide genomic size range.

  9. The pollen season dynamics and the relationship among some season parameters (start, end, annual total, season phases) in Kraków, Poland, 1991-2008.

    Science.gov (United States)

    Myszkowska, D; Jenner, B; Stępalska, D; Czarnobilska, E

    2011-09-01

    The dynamics of 15 taxa pollen seasons in Kraków, in 1991-2008 was monitored using a Burkard volumetric spore trap of the Hirst design. The highest daily pollen concentrations were achieved in the first half of May, and they were caused mainly by Betula and Pinus pollen. The second period of the high concentrations took place from the middle of July to the end of August (mainly Urtica pollen). Tree pollen seasons were shorter (18-24 days) in comparison with the most herbaceous pollen seasons (73-89 days), except at Artemisia and Ambrosia seasons (30 and 24 days, respectively). The season phases (percentyles) of the spring and late-summer taxa were the most variable in the consecutive years. The highest annual sums were noted for Urtica, Poaceae (herbaceous pollen seasons) and for Betula, Pinus, Alnus (tree pollen seasons), and the highest variability of annual totals was stated for Urtica, Populus, Fraxinus and the lowest for Ambrosia, Corylus, Poaceae. For the plants that pollinate in the middle of the pollen season (Quercus, Pinus and Rumex), the date of the season start seems not to be related to the season end, while for late pollen seasons, especially for Ambrosia and Artemisia, the statistically negative correlation between the start and the end season dates was found. Additionally, for the most studied taxa, the increase in annual pollen totals was observed. The presented results could be useful for the allergological practice and general botanical knowledge.

  10. A Correction Method Suitable for Dynamical Seasonal Prediction

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong; LIN Zhaohui

    2006-01-01

    Based on the hindcast results of summer rainfall anomalies over China for the period 1981-2000 by the Dynamical Climate Prediction System (IAP-DCP) developed by the Institute of Atmospheric Physics,a correction method that can account for the dependence of model's systematic biases on SST anomalies is proposed. It is shown that this correction method can improve the hindcast skill of the IAP-DCP for summer rainfall anomalies over China, especially in western China and southeast China, which may imply its potential application to real-time seasonal prediction.

  11. Amino acids in dew - origin and seasonal variation

    Science.gov (United States)

    Scheller, Edwin

    At two sites in the Armenhof district, 10 km east of Fulda, Germany, dew samples were collected from June 1996 to June 1997 and investigated for free and protein-bound amino acids. On account of the high pollen content, at the beginning of June 1996 and in May 1997 total amino acid concentrations were 53-390 μmol l -1, in one sample 922 μmol l -1. At other times the concentration in dew was 8-164 μmol l -1. On 4 and 5 June 1996 the diluted free amino acid fraction (DFAA) of the total hydrolysed amino acids (THAA) at both sites amounted to 35-44% and was predominantly arginine, proline and glutamine/glutamate. Likewise on 11 March 1997 the fraction of DFAA was found to be 39.5% with extremely high arginine and proline fractions. At other times the DFAA-fraction was in the range 14-26%. From July 1996 to June 1997 the amino acid concentrations in the vapours rising from a meadow were also measured and it ranged from 8 to 51 μmol l -1. From July to October 1996 the amino acid composition in the hydrolysates of dew samples and meadow vapours collected overnight were almost identical. The DFAA fraction in the condensation water collected overnight from the meadow varied from 18 to 40%. From 4 to 6 June 1996, on 11 and 13 March 1997 and in the period 16-20 May 1997, the amino acid distribution in dew showed much variation. The percentage fraction of arginine and proline in the hydrolysate increased greatly, whereas that of glycine and serine decreased. The large increase in proline and arginine in hydrolysate is attributable solely to the large amounts of free arginine and proline. This effect occurred in both 1996 and 1997 over several days at both sites at any one time and therefore appears confirmed.

  12. Seasonal variations in dermatologic and dermatopathologic diagnoses: a retrospective 15-year analysis of dermatopathologic data.

    Science.gov (United States)

    Harvell, Jeff D; Selig, Daniel J

    2016-10-01

    Certain dermatologic conditions are known to show seasonal variations in frequency, the reasons for which are unclear but in some cases may be attributable to changes in ambient weather conditions. The current study was conducted to determine whether seasonal trends might exist for dermatologic conditions including erythema multiforme, guttate psoriasis, erythema dyschromicum perstans (ashy dermatosis), pityriasis lichenoides, and pityriasis rosea. Data were derived from a 15-year retrospective review of electronic records from a large dermatopathology laboratory located in the mid-Atlantic region of the USA. Numbers of diagnoses per month and "per season" were determined. Pairwise comparisons of seasonal data were made using two-sample t-tests with significance set at P ≤ 0.05. Perniosis (chilblains) was significantly more common in winter and spring (P = 0.001). Hand, foot, and mouth disease was statistically more prevalent in summer and autumn (P = 0.028). Erythema multiforme was most common in spring and summer (P = 0.004). Grover's disease was most common in winter and spring (P = 0.000039). Guttate psoriasis was non-significantly more common in winter and spring (P = 0.076). No statistically significant seasonal variation was found for erythema dyschromicum perstans (P = 0.899), pityriasis rosea (P = 0.727), or pityriasis lichenoides (P = 0.366). This study found statistically significant seasonal trends for several dermatologic conditions. The study was primarily epidemiologic and was not intended to address histopathologic differences that might underlie the seasonal variations observed. However, further investigation of seasonal differences in the histopathology of erythema multiforme may prove interesting. © 2016 The International Society of Dermatology.

  13. Seasonal variation and innate immune responses of spleen in fresh-water snake, Natrix piscator

    Directory of Open Access Journals (Sweden)

    Manish Kumar Tripathi

    2014-03-01

    Full Text Available Innate immunity provides first line defense in all animals against pathogens and parasites. There is seasonal variation in pathogen prevalence and disease because of the seasonal lifecycle of the parasite and due to annual variation in the infectivity of pathogens. Organisms face seasonal stress by regulating their internal physiology, i.e. by secreting hormones. Melatonin and sex steroids contribute to the seasonal redistribution of immunological activity including winter-time up-regulation of some immune responses, and reproduction-related immunosuppression. Present study aims to understand seasonal variation in splenocyte innate immune response in the fresh-water snake, Natrix piscator. Reptiles represent the pivotal phylogenic group as they were the ancestor of both birds and mammals and they are the only ectothermic amniotes providing the key link between ectothermic anamniotic fishes and amphibians, and endothermic amniotic birds and mammals; a greater study of reptilian innate immune response will provide important insights into the evolutionary history of vertebrate immunity. Animals were mildly anaesthetized and the spleen was isolated aseptically. Spleen was used for calculating splenosomatic index, cellularity and macrophage phagocytosis. Spleen size has a trend to be high in autumn and winter months and low in spring and summer, though data were not significant. Spleen cellularity was recorded high in winter months and again in September; while it remained low during rest of the year. No definite pattern was observed in phagocytosis by splenic macrophages. The percent phagocytosis varied between 42 to 60 %, being highest in month of February. It is concluded that seasonal variation in splenocyte immune response provides a mechanism that suites best to the organism and which might coincide with the pathogen prevalence. Seasonal cycle of immune response is helpful in understanding the disease processes in animals and the direct

  14. Annual variation of carbon flux and impact factors in the tropical seasonal rain forest of Xishuangbanna, SW China

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    <正>Two years of eddy covariance measurements of above- and below-canopy carbon fluxes and static opaque chamber and gas chromatography technique measurements of soil respiration for three treatments (bare soil, soil+litterfall, soil+litterfall+seedling) were carried out in a tropical seasonal rain forest. In addition, data of photosynthesis of dominant tree species and seedlings, leaf area index, litter production and decomposing speed, soil moisture, soil temperature and photosynthetic photon flux density within the forest were all measured concurrently. Data from January 2003 to December 2004 are used to present annual variability of carbon flux and relationships between carbon flux and impact factors. The results show that carbon flux of this forest presented unusual tendency of annual variation; above-canopy carbon fluxes were negative in the dry season (November-April) and mainly positive in the rainy season, but overall the forest is a carbon sink. Carbon flux has obviously diurnal variation in this tropical seasonal rain forest. Above-canopy carbon fluxes were negative in the daytime and absolute values were larger in the dry season than that in the rainy season, causing the forest to act as a carbon sink; at night, carbon fluxes were mainly positive, causing the forest to act as a carbon source. Dominant tree species have greater photosynthesis capability than that of seedlings, which have a great effect on above-canopy carbon flux. There was a significant correlation between above-canopy carbon flux and rate of photosynthesis of tree species. There was also a significant correlation between above-canopy carbon flux and rate of photosynthesis of seedlings; however, the below-canopy carbon flux was only significantly correlated with rate of photosynthesis of seedlings during the hot-dry season. Soil respiration of the three treatments displayed a markedly seasonal dynamic; in addition, above-canopy carbon fluxes correlated well with soil respiration

  15. Variational principles for stochastic fluid dynamics.

    Science.gov (United States)

    Holm, Darryl D

    2015-04-08

    This paper derives stochastic partial differential equations (SPDEs) for fluid dynamics from a stochastic variational principle (SVP). The paper proceeds by taking variations in the SVP to derive stochastic Stratonovich fluid equations; writing their Itô representation; and then investigating the properties of these stochastic fluid models in comparison with each other, and with the corresponding deterministic fluid models. The circulation properties of the stochastic Stratonovich fluid equations are found to closely mimic those of the deterministic ideal fluid models. As with deterministic ideal flows, motion along the stochastic Stratonovich paths also preserves the helicity of the vortex field lines in incompressible stochastic flows. However, these Stratonovich properties are not apparent in the equivalent Itô representation, because they are disguised by the quadratic covariation drift term arising in the Stratonovich to Itô transformation. This term is a geometric generalization of the quadratic covariation drift term already found for scalar densities in Stratonovich's famous 1966 paper. The paper also derives motion equations for two examples of stochastic geophysical fluid dynamics; namely, the Euler-Boussinesq and quasi-geostropic approximations.

  16. Seasonal variations in notification of active tuberculosis cases in China, 2005-2012.

    Directory of Open Access Journals (Sweden)

    Xin-Xu Li

    Full Text Available BACKGROUND: Although seasonal variation in tuberculosis (TB incidence has been described in many countries, it remains unknown in China. METHODS: A time series decomposition analysis (X-12-ARIMA was performed to examine the seasonal variation in active TB cases nationwide from 2005 through 2012 in China. Seasonal amplitude was calculated for the evaluation of TB seasonal variation. RESULTS: A total of 7.78 million active TB cases were reported over a period of 8 years. A spring peak (April was observed with seasonal amplitude of 46.3%, compared with the winter trough (February. Most cases in provinces with subtropical and tropical monsoon climate showed lower amplitudes than those in temperate continental, plateau and mountain climate regions. The magnitude of seasonality varied inversely with annual average temperature, r (95% CI = -0.71 (-0.79, -0.61. The seasonal amplitudes were 56.7, 60.5, 40.6, 46.4 and 50.9% for patients aged ≤14, 15-24, 25-44, 45-64, and ≥65 years, respectively. Students demonstrated greater seasonal amplitude than peasants, migrant workers and workers (115.3% vs. 43.5, 41.6 and 48.1%. Patients with pulmonary TB had lower amplitude compared to patients with pleural and other extra-pulmonary TB (EPTB (45.9% vs. 52.0 and 56.3%. Relapse cases with sputum smear positive TB (SS+ TB had significantly higher seasonal amplitude compared to new cases with sputum smear positive TB (52.2% vs. 41.6%. CONCLUSIONS: TB is a seasonal disease in China. The peak and trough of TB transmission actually are in winter and in autumn respectively after factors of delay are removed. Higher amplitudes of TB seasonality are more likely to happen in temperate continental, plateau and mountain climate regions and regions with lower annual average temperature, and young person, students, patients with EPTB and relapse cases with SS+ TB are more likely to be affected by TB seasonality.

  17. Seasonal Variation of Ozone in the Tropical Lower Stratosphere: Southern Tropics are Different from Northern Tropics

    Science.gov (United States)

    Stolarski, Richard S.; Waugh, Darryn W.; Wang, Lei,; Oman, Luke D.; Douglass, Anne R.; Newman, Paul A.

    2014-01-01

    We examine the seasonal behavior of ozone by using measurements from various instruments including ozonesondes, Aura Microwave Limb Sounder, and Stratospheric Aerosol and Gas Experiment II. We find that the magnitude of the annual variation in ozone, as a percentage of the mean ozone, exhibits a maximum at or slightly above the tropical tropopause. The maximum is larger in the northern tropics than in the southern tropics, and the annual maximum of ozone in the southern tropics occurs 2 months later than that in the northern tropics, in contrast to usual assumption that the tropics can be treated as a horizontally homogeneous region. The seasonal cycles of ozone and other species in this part of the lower stratosphere result from a combination of the seasonal variation of the Brewer-Dobson circulation and the seasonal variation of tropical and midlatitude mixing. In the Northern Hemisphere, the impacts of upwelling and mixing between the tropics and midlatitudes on ozone are in phase and additive. In the Southern Hemisphere, they are not in phase. We apply a tropical leaky pipe model independently to each hemisphere to examine the relative roles of upwelling and mixing in the northern and southern tropical regions. Reasonable assumptions of the seasonal variation of upwelling and mixing yield a good description of the seasonal magnitude and phase in both the southern and northern tropics. The differences in the tracers and transport between the northern and southern tropical stratospheres suggest that the paradigm of well-mixed tropics needs to be revised to consider latitudinal variations within the tropics.

  18. Latitudinal range influences the seasonal variation in the foraging behavior of marine top predators.

    Directory of Open Access Journals (Sweden)

    Stella Villegas-Amtmann

    Full Text Available Non-migratory resident species should be capable of modifying their foraging behavior to accommodate changes in prey abundance and availability associated with a changing environment. Populations that are better adapted to change will have higher foraging success and greater potential for survival in the face of climate change. We studied two species of resident central place foragers from temperate and equatorial regions with differing population trends and prey availability associated to season, the California sea lion (Zalophus californianus (CSL whose population is increasing and the endangered Galapagos sea lion (Zalophus wollebaeki (GSL whose population is declining. To determine their response to environmental change, we studied and compared their diving behavior using time-depth recorders and satellite location tags and their diet by measuring C and N isotope ratios during a warm and a cold season. Based on latitudinal differences in oceanographic productivity, we hypothesized that the seasonal variation in foraging behavior would differ for these two species. CSL exhibited greater seasonal variability in their foraging behavior as seen in changes to their diving behavior, foraging areas and diet between seasons. Conversely, GSL did not change their diving behavior between seasons, presenting three foraging strategies (shallow, deep and bottom divers during both. GSL exhibited greater dive and foraging effort than CSL. We suggest that during the warm and less productive season a greater range of foraging behaviors in CSL was associated with greater competition for prey, which relaxed during the cold season when resource availability was greater. GSL foraging specialization suggests that resources are limited throughout the year due to lower primary production and lower seasonal variation in productivity compared to CSL. These latitudinal differences influence their foraging success, pup survival and population growth reflected in

  19. Seasonal variations of CO2 and 222Rn in a mediterranean sinkhole - spring (Causse d’Aumelas, SE France

    Directory of Open Access Journals (Sweden)

    Batiot-Guilhe Christelle

    2007-01-01

    Full Text Available Carbon dioxide and 222Rn monitoring of the atmosphere of a Mediterranean sink hole - spring (SE France during two hydrological cycles (from September 2004 to September 2006 showed seasonal variations with very high concentrations during summer (greater than 6% and 20 000 Bq/m3, respectively. Gas dynamics in caves often show seasonal variations.Meteorological parameters (barometric pressure and temperature mainly, cave geometry and fracture networks control exchanges between the cavity and outside atmosphere. Carbon dioxide and 222Rn may have different sources (atmosphere, soil, bedrock, deep gas diffusion, in situ oxidation of organic matter and, in some caves, the key role of swift underground streams.For a CO2 origin, 13C measurements on water and gas samples taken into the cavity suggest a superficial origin. Radon-222 appears to be locally produced and transported by biogenic CO2. Further investigations will be carried out in order to study the relationship of gas-level variations with barometric pressure variations and piezometric level fluctuations within the aquifer.

  20. Seasonal Variation of Polyciclic Aromatic Hydrocarbons in the Atmosphere of Mexico City

    Science.gov (United States)

    Mugica, V.; Hernandez, S.; Torres, M.; García, R.

    2007-05-01

    With the aim to determine concentrations levels and seasonal variation of polyaromatic hydrocarbons (PAH) in the northern of Mexico City, three sampling campaigns were performed during cold dry season, rain season and hot dry season in 2005. Particle-bound polycyclic aromatic hydrocarbons were collected on quartz fiber filters and gas-phase PAH was collected into polyurethane foam (PUF) with XAD-4 resin. Both types of samples were extracted with a dichloromethane and acetonitrile (2:1). Quantification of 17 PAH was carried out using gas chromatography .mass spectrometry (GC-MS). Recovery factors were determined by spiking filters with standard (NIST SRM 1647c). Average PM10 concentrations during the three seasons were 62.3, 68.9 and 131 μ gm- 3 for hot dry season, rainy season and hot dry season respectively. In the hot dry season the total of quantified PAH in particles was in average 1.99±0.82 ngm-3 and the dominant PAH compounds were Pyr, BghiP and Cry; the rainy season presented a total of 2.8± 1.2 ngm-3 of quantified PAH in particles and the pore abundant PAH were BaA, BbF, and BghiP; the cold dry season presented the highest concentrations with an average of quantified PAH in particles of 15.5± 4.9 ng-3 and BbF, BaA, and BghiP were the most abundant compounds. The most abundant PAH in the gaseous phase in the three seasons were naphtalene, pyrene and acenaphtylene with average concentrations of 132, 2.7 and 2.1 ngm-3 in the hot dry season, 18.1, 0.47 and 1.8 ngm-3 in the rainy season and 58, 1.71 and 2.37 ngm-3 in the cold dry season. Principal component analyses and cluster analyses were applied to relate the PAH concentrations with their sources.

  1. Environmental Determinants Influencing Seasonal Variations of Bird Diversity and Abundance in Wetlands, Northern Region (Ghana

    Directory of Open Access Journals (Sweden)

    Collins Ayine Nsor

    2014-01-01

    Full Text Available The study assessed major environmental determinants influencing bird community in six wetlands over a 2-year period. A combination of visual and bird sounding techniques was used to determine the seasonal variations in bird abundance, while ordination techniques were performed to determine the influence of environmental factors on bird assemblage. A total of 1,169 birds from 25 species and 885 individuals from 23 species were identified in the wet and dry season, respectively. The shallow close marshes supported the greatest number of birds (P<0.05 compared to the riparian wetlands. Bird diversity was significantly higher in the wet season than in the dry season (F=4.101,P<0.05. Cattle egret (Bubulcus ibis and marsh warbler (Acrocephalus palustris were the most abundant. Using the IUCN “Red List” database guide, we noted that 96.2% of birds identified were least concern (LC. The yellow weaver bird (Ploceous megarhrynchus was the only vulnerable species (VU and represented 3.8%. From the three variables tested, bushfire and farming practices were the major threats and cumulatively explained 15.93% (wet season and 14.06% (dry season variations in bird diversity and abundance. These findings will help wetland managers design conservation measures to check current threats on birds from becoming vulnerable in the future.

  2. Seasonal variations in groundwater upwelling zones in a Danish lowland stream analyzed using Distributed Temperature Sensing (DTS)

    DEFF Research Database (Denmark)

    Matheswaran, Karthikeyan; Blemmer, Morten; Rosbjerg, Dan;

    2014-01-01

    , antecedent precipitation and presence of fractured clayey till in the stream reach were deemed as the vital factors causing apparent seasonal variation in the locations of upwelling zones, prompting use of DTS not only in preconceived scenarios of large diurnal temperature change but rather a long......, to assess the seasonal dynamics of groundwater inflow zones using high spatial (1 m) and temporal (3 minutes) resolution of water temperature measurements. Four simple criteria consisting of 30 min average temperature at 16:00, mean and standard deviation of diurnal temperatures, and the day......–night temperature difference were applied to three DTS datasets representing stream temperature responses to the variable meteorological and hydrological conditions prevailing in summer, winter and spring. The standard deviation criterion was useful to identify groundwater discharge zones in summer and spring...

  3. Role of seasonality on predator-prey-subsidy population dynamics.

    Science.gov (United States)

    Levy, Dorian; Harrington, Heather A; Van Gorder, Robert A

    2016-05-07

    The role of seasonality on predator-prey interactions in the presence of a resource subsidy is examined using a system of non-autonomous ordinary differential equations (ODEs). The problem is motivated by the Arctic, inhabited by the ecological system of arctic foxes (predator), lemmings (prey), and seal carrion (subsidy). We construct two nonlinear, nonautonomous systems of ODEs named the Primary Model, and the n-Patch Model. The Primary Model considers spatial factors implicitly, and the n-Patch Model considers space explicitly as a "Stepping Stone" system. We establish the boundedness of the dynamics, as well as the necessity of sufficiently nutritional food for the survival of the predator. We investigate the importance of including the resource subsidy explicitly in the model, and the importance of accounting for predator mortality during migration. We find a variety of non-equilibrium dynamics for both systems, obtaining both limit cycles and chaotic oscillations. We were then able to discuss relevant implications for biologically interesting predator-prey systems including subsidy under seasonal effects. Notably, we can observe the extinction or persistence of a species when the corresponding autonomous system might predict the opposite.

  4. Spatial and seasonal variations of the contamination within water body of the Grand Canal, China.

    Science.gov (United States)

    Xiaolong, Wang; Jingyi, Han; Ligang, Xu; Qi, Zhang

    2010-05-01

    To delineate the character of contaminations in the Grand Canal, China, a three-year study (2004-2006) was conducted to investigate variations the water quality in the canal. Results showed that the variation of water quality within the Grand Canal was of there is remarkable spatial and seasonal heterogeneity regarding water quality within the Canal. Values of contaminants in dry-season were obviously higher than those in wet-season. Sites influenced strongly by industry and urbanization showed higher contents of nutrients and lower levels of dissolved oxygen in water body; moreover these sites were severely polluted by dissolved metals with the contents of cadmium, chromium and copper exceeding the Criteria Maximum Concentration (CMC), US EPA. Multivariate statistical analysis suggested nutrient and dissolved metals pollution was the dominant environmental problems within the Canal. Anthropogenic influences played a dominant role in the character of contaminations in the Grand Canal. Copyright 2010 Elsevier Ltd. All rights reserved.

  5. Seasonal variation of deep-sea bioluminescence in the Ionian Sea

    Energy Technology Data Exchange (ETDEWEB)

    Craig, Jessica, E-mail: j.craig@abdn.ac.u [University of Aberdeen, Oceanlab, Main Street, Newburgh, Aberdeenshire, AB41 6AA (United Kingdom); Jamieson, Alan J.; Bagley, Philip M.; Priede, Imants G. [University of Aberdeen, Oceanlab, Main Street, Newburgh, Aberdeenshire, AB41 6AA (United Kingdom)

    2011-01-21

    The ICDeep (Image Intensified Charge Coupled Device for Deep sea research) profiler was used to measure the density of deep bioluminescent animals (BL) through the water column in the east, west and mid-Ionian Sea and in the Algerian Basin. A west to east decrease in BL density was found. Generalized additive modelling was used to investigate seasonal variation in the east and west Ionian Sea (NESTOR and NEMO neutrino telescope sites, respectively) from BL measurements in autumn 2008 and spring 2009. A significant seasonal effect was found in the west Ionian Sea (p<0.001), where a deep autumnal peak in BL density occurred between 500 and 2400 m. No significant seasonal variation in BL density was found in the east Ionian Sea (p=0.07). In both spring and autumn, significant differences in BL density were found through the water column between the east and west Ionian Sea (p<0.001).

  6. Seasonal variation in soil and plant water potentials in a Bolivian tropical moist and dry forest

    NARCIS (Netherlands)

    Markesteijn, L.; Iraipi, J.; Bongers, F.; Poorter, L.

    2010-01-01

    We determined seasonal variation in soil matric potentials (¿soil) along a topographical gradient and with soil depth in a Bolivian tropical dry (1160 mm y-1 rain) and moist forest (1580 mm y-1). In each forest we analysed the effect of drought on predawn leaf water potentials (¿pd) and drought resp

  7. Assessment of the processes controlling seasonal variations of dissolved inorganic carbon in the North Sea

    NARCIS (Netherlands)

    Bozec, Yann; Thomas, Helmuth; Schiettecatte, Laure-Sophie; Borges, Alberto V.; Elkalay, Khalid; Baar, Hein J.W. de

    2006-01-01

    We used a seasonal North Sea data set comprising dissolved inorganic carbon (DIC), partial pressure of CO2 (pCO2), and inorganic nutrients to assess the abiotic and biological processes governing the monthly variations of DIC. During winter, advection and air–sea exchange of CO2 control and increase

  8. Impacts of Freshwater on the Seasonal Variations of Surface Salinity and Circulation in the Caspian Sea

    Science.gov (United States)

    2010-01-01

    Author’s personal copy Impacts of freshwater on the seasonal variations of surface salinity and circulation in the Caspian Sea A. Birol Kara a, Alan ...circulation. Izv. Atmos. Ocean. Phys. 44, 236–249. Large, W.G., Danabasoglu, G., Doney, S.C., McWilliams , J.C., 1997. Sensitivity to surface forcing and

  9. Seasonal variation of relapse rate in multiple sclerosis is latitude dependent

    NARCIS (Netherlands)

    Spelman, Tim; Gray, Orla; Trojano, Maria; Petersen, Thor; Izquierdo, Guillermo; Lugaresi, Alessandra; Hupperts, Raymond; Bergamaschi, Roberto; Duquette, Pierre; Grammond, Pierre; Giuliani, Giorgio; Boz, Cavit; Verheul, Freek; Oreja-Guevara, Celia; Barnett, Michael; Grand'Maison, Francois; Edite Rio, Maria; Lechner-Scott, Jeannette; Van Pesch, Vincent; Fernandez Bolanos, Ricardo; Flechter, Shlomo; Den Braber-Moerland, Leontien; Iuliano, Gerardo; Amato, Maria Pia; Slee, Mark; Cristiano, Edgardo; Saladino, Maria Laura; Paine, Mark; Vella, Norbert; Kasa, Krisztian; Deri, Norma; Herbert, Joseph; Moore, Fraser; Petkovska-Boskova, Tatjana; Alroughani, Raed; Savino, Aldo; Shaw, Cameron; Vucic, Steve; Santiago, Vetere; Bacile, Elizabeth Alejandra; Skromne, Eli; Poehlau, Dieter; Cabrera-Gomez, Jose Antonio; Lucas, Robyn; Butzkueven, Helmut

    2014-01-01

    OBJECTIVE: Previous studies assessing seasonal variation of relapse onset in multiple sclerosis have had conflicting results. Small relapse numbers, differing diagnostic criteria, and single region studies limit the generalizability of prior results. The aim of this study was to determine whether th

  10. Seasonal variation and formation mechanism of the South China Sea warm water

    Institute of Scientific and Technical Information of China (English)

    刘秦玉; 王东晓; 贾英来; 杨海军; 孙即霖; 杜岩

    2002-01-01

    -- The South China Sea warm water (SCSWW) is identified as the warm water body with temperature no less than 28C. There are three stages in the seasonal variation of the SCSWW. The SCSWW expands rapidly and deepens quickly in the developing stage. The warm water thickness decreases near the coast of Vietnam and increases near Palawan Island in the steady stage. The SCSWW flinches southward while its thickness off Palawan Island remains no less than 50 m in the flinching stage. The maximum thickness of the SCSWW is always located near the southeastern SCS. The seasonal variation of the SCSWW has a close relationship with seasonal variation of the thermocline. According to the analysis of the numerical experiment results from the Princeton Ocean Model (POM),the mechanism of the seasonal variation of the SCSWW can be interpreted as: ( 1 ) in the developing stage, the rapidly expanding and thickening feature of the SCSWW is mainly due to buoyancy flux effect (67% contribution). The weak wind and anticyclonic wind stress curl (22% contribution) present an environment which facilitates the accumulation of warm water; (2) in the steady stage, the decrease feature near the Vietnam coast and increase eature in southeast of the SCSWW thickness are mainly caused by wind stress (70% contribution); (3) in the flinching stage, the thickness reduction of the SCSWW is mainly due to upwelling and enhanced turbulent mixing caused by wind stress accounts for 60% ).

  11. Circulation in the western tropical Pacific Ocean and its seasonal variation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An assimilation data set based on the GFDL MOM3 model and the NODC XBT data set is used to examine the circulation in the western tropical Pacific and its seasonal variations. The assimilated and observed velocities and transports of the mean circulation agree well. Transports of the North Equatorial Current (NEC), Mindanao Current (MC), North Equatorial Countercurrent (NECC) west of 140°E and Kuroshio origin estimated with the assimilation data display the seasonal cycles, roughly strong in boreal spring and weak in autumn, with a little phase difference.The NECC transport also has a semi-annual fluctuation resuiting from the phase lag between seasonal cycles of two tropical gyres' recirculations. Strong in summer during the southeast monsoon period, the seasonal cycle of the Indonesian throughfiow (ITF) is somewhat different from those of its upstreams, the MC and New Guinea Coastal Current (NGCC), implying the monsoon's impact on it.

  12. Leptin mediates seasonal variation in some but not all symptoms of sickness in Siberian hamsters.

    Science.gov (United States)

    Carlton, Elizabeth D; Demas, Gregory E

    2014-11-01

    Many seasonally breeding species, including Siberian hamsters (Phodopus sungorus), exhibit seasonal variation in sickness responses. One hypothesis regarding the mechanism of this variation is that sickness intensity tracks an animal's energetic state, such that sickness is attenuated in the season that an animal has the lowest fat stores. Energetic state may be signaled via leptin, an adipose hormone that provides a signal of fat stores. Siberian hamsters respond to extended housing in short, winter-like days by reducing fat stores and leptin levels, relative to those housed in long, summer-like days. Sickness responses are also attenuated in short-day hamsters as compared to long-day hamsters. We hypothesized that leptin provides a physiological signal by which seasonally breeding animals modulate sickness responses, such that animals with higher leptin levels show increased sickness intensity. To test this, we provided short-day hamsters with a long-day-like leptin signal and assessed their responses to lipopolysaccharide (LPS), a sickness-inducing antigen. We compared these responses to short-day vehicle-, long-day vehicle-, and long-day leptin-treated hamsters. Unexpectedly, LPS induced a hypothermic response (rather than fever) in all groups. Short-day vehicle-treated hamsters exhibited the greatest LPS-induced hypothermia, and leptin treatment attenuated this response, making hypothermia more long-day-like. Contrary to our hypothesis, short-day leptin-treated hamsters showed the least pronounced LPS-induced anorexia among all groups. These results suggest that leptin may mediate some but not all aspects of seasonal sickness variation in this species. Future studies should be targeted at determining roles of other energetic hormones in regulating seasonal sickness response variation.

  13. Diurnal and seasonal variation of the brain serotonin system in healthy male subjects.

    Science.gov (United States)

    Matheson, Granville J; Schain, Martin; Almeida, Rita; Lundberg, Johan; Cselényi, Zsolt; Borg, Jacqueline; Varrone, Andrea; Farde, Lars; Cervenka, Simon

    2015-05-15

    The mammalian circadian clock underlies both diurnal and seasonal changes in physiology, and its function is thought to be disturbed in both seasonal and non-seasonal depression. In humans, molecular imaging studies have reported seasonal changes in the serotonin system. Despite the role of the circadian clock in generating seasonal physiological changes, however, diurnal variation of serotonin receptors and transporters has never been directly studied in humans. We used positron emission tomography to examine diurnal and seasonal changes in the serotonin 5-HT1A receptor and serotonin transporter in two large cohorts of healthy male subjects, employing a cross-sectional design. In 56 subjects measured with [(11)C]WAY-100635, we observed diurnal increases in the availability of 5-HT1A receptors in the cortex. In 40 subjects measured with [(11)C]MADAM, a decrease in 5-HTT was observed in the midbrain across the day. We also found seasonal changes in the 5-HT1A receptor in serotonin projection regions, with higher availability on days with a longer duration of daylight. Our observation that serotonin receptor and transporter levels may change across the day in humans is corroborated by experimental research in rodents. These findings have important implications for understanding the relationship between the circadian and serotonin systems in both the healthy brain and in affective disorders, as well as for the design of future molecular imaging studies.

  14. Spectra and vegetation index variations in moss soil crust in different seasons, and in wet and dry conditions

    Science.gov (United States)

    Fang, Shibo; Yu, Weiguo; Qi, Yue

    2015-06-01

    Similar to vascular plants, non-vascular plant mosses have different periods of seasonal growth. There has been little research on the spectral variations of moss soil crust (MSC) over different growth periods. Few studies have paid attention to the difference in spectral characteristics between wet MSC that is photosynthesizing and dry MSC in suspended metabolism. The dissimilarity of MSC spectra in wet and dry conditions during different seasons needs further investigation. In this study, the spectral reflectance of wet MSC, dry MSC and the dominant vascular plant (Artemisia) were characterized in situ during the summer (July) and autumn (September). The variations in the normalized difference vegetation index (NDVI), biological soil crust index (BSCI) and CI (crust index) in different seasons and under different soil moisture conditions were also analyzed. It was found that (1) the spectral characteristics of both wet and dry MSCs varied seasonally; (2) the spectral features of wet MSC appear similar to those of the vascular plant, Artemisia, whether in summer or autumn; (3) both in summer and in autumn, much higher NDVI values were acquired for wet than for dry MSC (0.6 ∼ 0.7 vs. 0.3 ∼ 0.4 units), which may lead to misinterpretation of vegetation dynamics in the presence of MSC and with the variations in rainfall occurring in arid and semi-arid zones; and (4) the BSCI and CI values of wet MSC were close to that of Artemisia in both summer and autumn, indicating that BSCI and CI could barely differentiate between the wet MSC and Artemisia.

  15. Seasonal variation of newly notified pulmonary tuberculosis cases from 2004 to 2013 in Wuhan, China.

    Directory of Open Access Journals (Sweden)

    Xiaobing Yang

    Full Text Available BACKGROUND: Although there was a report about the seasonal variation in Wuhan city, it only analyzed the prevalence data of pulmonary tuberculosis (TB cases, and just studied the seasonality by subgroup of smear positive and negative from 2006 to 2010 by spectral analysis. In this study, we investigated the seasonality of the total newly notified pulmonary TB cases by subgroups such as time period, sex, age, occupation, district, and sputum smear result from 2004 to 2013 in Wuhan by a popular seasonal adjustment model (TRAMO-SEATS. METHODS: Monthly pulmonary TB cases from 2004 to 2013 in Wuhan were analyzed by the TRAMO-SEATS seasonal adjustment program. Seasonal amplitude was calculated and compared within the subgroups. RESULTS: From 2004 to 2013, there were 77.76 thousand newly notified pulmonary TB cases in Wuhan, China. There was a dominant peak spring peak (March with seasonal amplitude of 56.81% and a second summer peak (September of 43.40%, compared with the trough month (December. The spring seasonal amplitude in 2004-2008 was higher than that of 2009-2013(P0.05. However, there were significant differences in spring seasonal amplitude by occupation, with amplitude ranging from 59.37% to 113.22% (P0.05. There were significant differences in summer seasonal amplitude by age, with amplitude ranging from 36.05% to 100.09% (P<0.05. Also, there were significant differences in summer seasonal amplitude by occupation, with amplitude ranging from 43.40% to 109.88% (P<0.05. CONCLUSIONS: There was an apparent seasonal variation in pulmonary TB cases in Wuhan. We speculated that spring peak in our study was most likely caused by the increased reactivation of the latent TB due to vitamin D deficiency and high PM2.5 concentration, while the summer peak was mainly resulted from the enhanced winter transmission due to indoor crowding in winter, overcrowding of public transportation over the period of the Spring Festival and health care seeking delay in

  16. Seasonal variation for the antidiabetic activity ofLoranthus micranthus methanol extract

    Institute of Scientific and Technical Information of China (English)

    Patience Ogoamaka Osadebe; Edwin Ogechukwu Omeje; Philip Felix Uzor; Ernest Kenechukwu David; Damian Chiedozie Obiorah

    2010-01-01

    Objective:To determine the season in which the Eastern Nigeria mistletoe,Loranthus micranthus, parasitic onPersea americana possesses optimum antidiabetic activity and to determine the seasonal variation in the constituents.Methods: The antidiabetic activities of the aqueous methanol extracts of the leaves of Eastern Nigeria mistletoe,Loranthus micranthus, harvested in two seasons of the year, the onset of rainy season (April) and the peak of rainy season (July) were compared. The tests were carried out on six (6) groups (A-F) of alloxan-induced diabetic rats. Groups A and B received 200 mg/kg and 400 mg/kg of the April sample extracts respectively while groups C and D received same doses of the July sample extracts. Group E and F which were the positive and negative controls received 10 mg/kg of glibenclamide and 2 ml/kg of 3% tween 20 respectively. The blood glucose levels of the animals were monitored hourly with a glucometer for six hours. The phytochemical analysis of the plant extracts were also carried out by standard procedures.Results: The results showed that group A and B exhibited significant (P0.05) FBS reduction (15.9%) while group D exhibited highly significant (P<0.01) reduction (47.5%) with the maximum reduction occurring after 6 hours. The phytochemical analysis of the crude methanol extracts revealed the presence of carbohydrates, glycosides, saponins, tannins, flavonoids, steroids, terpenoids, acidic compounds, resins and oils. These were present in different proportions in both seasons.Conclusions: This study shows that there is a seasonal, dose-dependent variation in the chemical compositionviz-a-viz the antidiabetic activity of the plant under study. This activity is highest at the peak of the rainy season.

  17. Seasonal variations of virus- and nanoflagellate-mediated mortality of heterotrophic bacteria in the coastal ecosystem of subtropical western Pacific

    Directory of Open Access Journals (Sweden)

    A. Y. Tsai

    2013-05-01

    Full Text Available Since viral lysis and nanoflagellate grazing differ in their impact on the aquatic food web, it is important to assess the relative importance of both bacterial mortality factors. In this study, an adapted version of the modified dilution method was applied to simultaneously estimate the impact of both virus and nanoflagellate grazing on the mortality of heterotrophic bacteria. A series of experiments was conducted monthly from April to December 2011 and April to October 2012. The growth rates of bacteria we measured ranged from 0.078 h−1 (April 2011 to 0.42 h−1 (September 2011, indicating that temperature can be important in controlling the seasonal variations of bacterial growth. Furthermore, it appeared that seasonal changes in nanoflagellate grazing and viral lysis could account for 34% to 68% and 13% to 138% of the daily removal of bacterial production, respectively. We suggest that nanoflagellate grazing might play a key role in controlling bacterial biomass and might exceed the impact of viral lysis during the summer period (July to August because of the higher abundance of nanoflagellates at that time. Viral lysis, on the other hand, was identified as the main cause of bacterial mortality between September and December. Based on these findings in this study, the seasonal variations in bacterial abundance we observed can be explained by a scenario in which both growth rates and loss rates (grazing + viral lysis influence the dynamics of the bacteria community.

  18. LEGENDRE SERIES SOLUTIONS FOR TIME-VARIATION DYNAMICS

    Institute of Scientific and Technical Information of China (English)

    Cao Zhiyuan; Zou Guiping; Tang Shougao

    2000-01-01

    In this topic, a new approach to the analysis of time-variation dynamics is proposed by use of Legendre series expansion and Legendre integral operator matrix. The theoretical basis for effective solution of time-variation dynamics is therefore established, which is beneficial to further research of time-variation science.

  19. Seasonal Variations of the East Asian Subtropical Westerly Jet and the Thermal Mechanism

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The seasonal variations of the intensity and location of the East Asian subtropical westerly jet (EAWJ)and the thermal mechanism are analyzed by using NCEP/NCAR monthly reanalysis data from 1961 to 2000.It is found that the seasonal variation of the EAWJ center not only has significant meridional migration, but also shows the rapid zonal displacements during June-July. Moreover, there exists zonal inconsistency in the northward shift process of the EAWJ axis. Analysis on the thermal mechanism of the EAWJ seasonal variations indicates that the annual cycle of the EAWJ seasonal variation matches very well with the structure of the meridional difference of air temperature, suggesting that the EAWJ seasonal variation is closely related to the inhomogeneous heating due to the solar radiation and the land-sea thermal contrast. Through investigating the relation between the EAWJ and the heat transport, it is revealed that the EAWJ weakens and shifts northward during the warming period from wintertime to summertime, whereas the EAWJ intensifies and shifts southward during the cooling period from summertime to wintertime. The meridional difference of the horizontal heat advection transport is the main factor determining the meridional temperature difference. The meridional shift of the EAWJ follows the location of the maximum meridional gradient of the horizontal heat advection transport. During the period from April to October, the diabatic heating plays the leading role in the zonal displacement of the EAWJ center. The diabatic heating of the Tibetan Plateau to the mid-upper troposphere leads to the rapid zonal displacement of the EAWJ center during June-July.

  20. Seasonal Variation of Soil Resistivity and Soil Temperature in Bayelsa State

    Directory of Open Access Journals (Sweden)

    John T. Afa

    2010-01-01

    Full Text Available Problem statement: Due to the climatic variation for the year and it's sever harmattan during the month of December to March with the high keraunic level (80-90 in the areas, it was necessary to know the seasonal variation of soil resistivity. The seasonal variation and the nature of soil have considerable influence on electrical characteristics and therefore affect the earthling system performance. Approach: Eighteen sites were chosen from three main soil divisions. The soil resistivity was taken in each of the site at depths of 0.5, 0.8 and 1.2 m using the four point test instrument (Wenner Method. From the selected sites in the three soil divisions the temperature was also taken at depths of 0.2, 0.5, 0.8 and 1.0 m. Results: The coefficient of seasonal variation at the depth of 0.5 m was high and reduced drastically at a depth of 1.2 m. The soil temperature was higher than the ambient temperature at the depth of 0.2 m during the months of December to March. From 0.8 m depth and below the temperature reduced even during the dry seasons. Conclusion: The coefficient of seasonal variation of soil at the depth of 0.8 and 1.2 m was small (1.8-3.0 throughout the year in all soil types. That indicates the high water level and or the permanent moisture table which gives an advantage to low soil resistivity for buried conductors and electrodes in the area.

  1. Population dynamic of the swallowtail butterfly, Papilio polytes (Lepidoptera: Papilionidae) in dry and wet seasons

    OpenAIRE

    SUWARNO

    2010-01-01

    Suwarno (2010) Population dynamic of the swallowtail butterfly, Papilio polytes (Lepidoptera: Papilionidae) in dry and wet seasons. Biodiversitas 11: 19-23. The population dynamic of Papilio polytes L. (Lepidoptera: Papilionidae) in dry and wet seasons was investigated in the citrus orchard in Tasek Gelugor, Pulau Pinang, Malaysia. Population of immature stages of P. polytes was observed alternate day from January to March 2006 (dry season, DS), from April to July 2006 (secondary wet season, ...

  2. PATIENT DEMOGRAPHIC, RISK FACTORS AND SEASONAL VARIATION IN ONSET OF STROKE

    Directory of Open Access Journals (Sweden)

    M. K. M. Kathyayani

    2016-10-01

    Full Text Available BACKGROUND Existence of particular chronobiological pattern in onset of acute cerebrovascular diseases characterised by circannual rhythms has been detected. India is a subtropical country with clear seasonal variations in weather conditions. Stroke causes death and disability worldwide. Seasons may influence stroke occurrence. The mechanisms underlying these seasonal variations of stroke are not fully understood, but a possible reason may include seasonal variation of biological factors such as arterial blood pressure, serum lipid levels and other blood components. Better understanding and controlling of risk factors associated with onset of stroke will improve the disease prevention. The objective of the present study is to examine the role of possible precipitating or triggering factors. This study reviews records of patients with stroke attending the Department of Medicine, KGH, Visakhapatnam. MATERIALS AND METHODS Patients with diagnosis of stroke attending the Department of Medicine, KGH, Visakhapatnam, were selected. Computed tomographic types of stroke, both ischaemic and haemorrhagic and risk factors associated were considered with tropical seasonal variation. RESULTS A total of 150 stroke patients were included in the study of which 93 (62% were males, 57 (38% were females and 46% in 50-65 years age group, 4% in 20-35 years, 28% in 35-50 years, 22% in 65-80 years and above age groups. Of the total, 93.33% presented with 1st attack and only 6.66% presented with recurrent stroke. The prevalence of types of stroke was: ischaemic stroke 54.66%, haemorrhagic stroke 45.33%. The prevalence of risk factors associated with stroke was - male gender 62%, smoking 56.66%, hypertension 56%, age >50 years 46%, alcohol consumption 43%, hyperlipidaemia 16.66%, consumption of alcohol and smoking together 13.33%, valvular heart diseases 6.66%. A high seasonal prevalence was observed in winter season (50.66%. CONCLUSION This study revealed that male

  3. Seasonal variation of atmospheric Pb-210 and Al in the western North Pacific region

    Science.gov (United States)

    Tsunogai, Shizuo; Kurata, Takayoshi; Suzuki, Toshitaka; Yokota, Kiichiro

    1988-11-01

    The atmospheric concentrations of Pb-210 over a period of two years were determined from aerosol samples collected at six stations in the western North Pacific. The results are compared with those for Al, showing that, although Pb-210 concentrations vary widely from week to week, the degree of variation is about half of that for Al. For Pb-210, the year-to-year variation is not pronounced and the seasonal variation is well represented by a sine curve. The results suggest that Pb-210 has a longer residence time than Al, because Pb-210 is transported through higher altitudes and is deposited more evenly onto the earth's surface and the ocean.

  4. Seasonal drought predictability in Portugal using statistical-dynamical techniques

    Science.gov (United States)

    Ribeiro, A. F. S.; Pires, C. A. L.

    2016-08-01

    Atmospheric forecasting and predictability are important to promote adaption and mitigation measures in order to minimize drought impacts. This study estimates hybrid (statistical-dynamical) long-range forecasts of the regional drought index SPI (3-months) over homogeneous regions from mainland Portugal, based on forecasts from the UKMO operational forecasting system, with lead-times up to 6 months. ERA-Interim reanalysis data is used for the purpose of building a set of SPI predictors integrating recent past information prior to the forecast launching. Then, the advantage of combining predictors with both dynamical and statistical background in the prediction of drought conditions at different lags is evaluated. A two-step hybridization procedure is performed, in which both forecasted and observed 500 hPa geopotential height fields are subjected to a PCA in order to use forecasted PCs and persistent PCs as predictors. A second hybridization step consists on a statistical/hybrid downscaling to the regional SPI, based on regression techniques, after the pre-selection of the statistically significant predictors. The SPI forecasts and the added value of combining dynamical and statistical methods are evaluated in cross-validation mode, using the R2 and binary event scores. Results are obtained for the four seasons and it was found that winter is the most predictable season, and that most of the predictive power is on the large-scale fields from past observations. The hybridization improves the downscaling based on the forecasted PCs, since they provide complementary information (though modest) beyond that of persistent PCs. These findings provide clues about the predictability of the SPI, particularly in Portugal, and may contribute to the predictability of crops yields and to some guidance on users (such as farmers) decision making process.

  5. Glacial cycles and solar insolation: the role of orbital, seasonal, and spatial variations

    Science.gov (United States)

    Kaufmann, R. K.; Juselius, K.

    2010-11-01

    We use a statistical model, the cointegrated vector autoregressive model, to evaluate the relative roles that orbital, seasonal, and spatial variations in solar insolation play in glacial cycles during the late Quaternary (390kyr - present). To do so, we estimate models of varying complexity and compare the accuracy of their in-sample simulations. Results indicate that variations in solar insolation associated with changes in Earth's orbit have the greatest explanatory power and that obliquity, precession, and eccentricity are needed to generate an accurate simulation of glacial cycles. Seasonal variations in insolation play a lesser role, while cumulative summer-time insolation has little explanatory power. Finally, solar insolation in the Northern Hemisphere generates the more accurate in-sample simulation of surface temperature while ice volume is simulated most accurately by solar insolation in the Southern Hemisphere.

  6. Severity of infection and seasonal variation of non-typhoid Salmonelle occurence in humans

    DEFF Research Database (Denmark)

    Gradel, K.O.; Dethlefsen, Claus; Schønheyder, H.C.

    2007-01-01

    Non-typhoid Salmonella infections may present as severe gastroenteritis necessitatinghospitalization and some patients become septic with bacteraemia. We hypothesized that theseasonal variation of non-typhoid Salmonella occurrence in humans diminishes with increasedseverity of infection. We...... examined the seasonal variation of non-typhoid Salmonella infections inthree patient groups with differing severity of infection: outpatients treated for gastroenteritis(n=1490); in-patients treated for gastroenteritis (n=492); and in-patients treated for bacteraemia(n=113). The study was population...... 2·4–4·2) forin-patients with gastroenteritis, and 1·6 (95% CI 1·0–2·8) for in-patients with bacteraemia. We conclude that the role of seasonal variation diminishes with increased severity of non-typhoidSalmonella infection....

  7. Comparison of seasonal variation in the fasting respiratory quotient of young Japanese, Polish and Thai women in relation to seasonal change in their percent body fat

    Directory of Open Access Journals (Sweden)

    Morinaka Tomoko

    2012-05-01

    Full Text Available Abstract Background From the viewpoint of human physiological adaptability, we previously investigated seasonal variation in the amount of unabsorbed dietary carbohydrates from the intestine after breakfast in Japanese, Polish and Thai participants. In this investigation we found that there were significant seasonal variations in the amount of unabsorbed dietary carbohydrates in Japanese and Polish participants, while we could not find significant seasonal variation in Thai participants. These facts prompted us to examine seasonal variations in the respiratory quotient after an overnight fast (an indicator of the ratio of carbohydrate and fat oxidized after the last meal with female university students living in Osaka (Japan, Poznan (Poland and Chiang Mai (Thailand. Methods We enrolled 30, 33 and 32 paid participants in Japan, Poland and Thailand, respectively, and measurements were taken over the course of one full year. Fasting respiratory quotient was measured with the participants in their postabsorptive state (after 12 hours or more fasting before respiratory quotient measurement. Respiratory quotient measurements were carried out by means of indirect calorimetry using the mixing chamber method. The percent body fat was measured using an electric bioelectrical impedance analysis scale. Food intake of the participants in Osaka and Poznan were carried out by the Food Frequency Questionnaire method. Results There were different seasonal variations in the fasting respiratory quotient values in the three different populations; with a significant seasonal variation in the fasting respiratory quotient values in Japanese participants, while those in Polish and Thai participants were non-significant. We found that there were significant seasonal changes in the percent body fat in the three populations but we could not find any significant correlation between the fasting respiratory quotient values and the percent body fat. Conclusions There were

  8. Evaluation of seasonal variations of remotely sensed leaf area index over five evergreen coniferous forests

    Science.gov (United States)

    Wang, Rong; Chen, Jing M.; Liu, Zhili; Arain, Altaf

    2017-08-01

    Seasonal variations of leaf area index (LAI) have crucial controls on the interactions between the land surface and the atmosphere. Over the past decades, a number of remote sensing (RS) LAI products have been developed at both global and regional scales for various applications. These products are so far only validated using ground LAI data acquired mostly in the middle of the growing season. The accuracy of the seasonal LAI variation in these products remains unknown and there are few ground data available for this purpose. We performed regular LAI measurements over a whole year at five coniferous sites using two methods: (1) an optical method with LAI-2000 and TRAC; (2) a direct method through needle elongation monitoring and litterfall collection. We compared seasonal trajectory of LAI from remote sensing (RS LAI) with that from a direct method (direct LAI). RS LAI agrees very well with direct LAI from the onset of needle growth to the seasonal peak (R2 = 0.94, RMSE = 0.44), whereas RS LAI declines earlier and faster than direct LAI from the seasonal peak to the completion of needle fall. To investigate the possible reasons for the discrepancy, the MERIS Terrestrial Chlorophyll Index (MTCI) was compared with RS LAI. Meanwhile, phenological metrics, i.e. the start of growing season (SOS) and the end of growing season (EOS), were extracted from direct LAI, RS LAI and MTCI time series. SOS from RS LAI is later than that from direct LAI by 9.3 ± 4.0 days but earlier than that from MTCI by 2.6 ± 1.9 days. On the contrary, for EOS, RS LAI is later than MTCI by 3.3 ± 8.4 days and much earlier than direct LAI by 30.8 ± 7.2 days. Our results suggest that the seasonal trajectory of RS LAI well captures canopy structural information from the onset of needle growth to the seasonal peak, but is greatly influenced by the decrease in leaf chlorophyll content, as indicated by MTCI, from the seasonal peak to the completion of needle fall. These findings have significant

  9. Seasonal variations of phytoplankton phosphorus stress in the Yellow Sea Cold Water Mass

    Institute of Scientific and Technical Information of China (English)

    WANG Dan; HUANG Bangqin; LIU Xin; LIU Guimei; WANG Hui

    2014-01-01

    The Yellow Sea is located between the China Mainland and the Korean Peninsula, representing a typical shallow epicontinental sea. The Yellow Sea Cold Water Mass (YSCWM) is one of the most important physical features in the Yellow Sea. The characteristics of vertical profiles and seasonal variations of biogenic ele-ments in the YSCWM may lead the variations of nutrient availability (e.g., phosphorus) and phosphorus stress of phytoplankton. In this study, the authors surveyed the seasonal variations of phytoplankton phos-phorus stress with emphasis on the effect of the YSCWM during the four cruises in April and October 2006, March and August 2007. Using both bulk and single-cell alkaline phosphatase activity (APA) assays, this study evaluated phosphorus status of phytoplankton community, succession of phytoplankton community and ecophysiological responses of phytoplankton to phosphorus in the typical region of the YSCWM. With the occurrence of the YSCWM, especially the variations of concentration of dissolved inorganic phospho-rus (DIP), the results of bulk APA appeared corresponding seasonal variations. Along Transects A and B, the mean APA in August was the highest, and that in March was the lowest. According to the ELF-labeled assay’s results, seasonal variations of the ELF-labeled percentages within dominant species indicated that diatoms were dominant in March, April and October, while dinoflagellates were dominant in August. During the four cruises, the ELF-labeled percentages of diatoms except Paralia sulcata showed that diatoms were not phosphorus deficient in April 2006 at all, but suffered from severe phosphorus stress in August 2007. In comparison, the ELF-labeled percentages of dinoflagellates were all above 50%during the four time series, which meant dinoflagellates such as Alexandrium and Scrippsiella, sustained perennial phosphorus stress.

  10. Seasonal variation of fecal indicator bacteria in storm events within the US stormwater database.

    Science.gov (United States)

    Pan, Xubin; Jones, Kim D

    2012-01-01

    Bacteria are one of the major causes of surface water impairments in the USA. Over the past several years, best management practices, including detention basins, manufactured devices, grass swales, filters and bioretention cells have been used to remove bacteria and other pollutants from stormwater runoff. However, there are data gaps in the comprehensive studies of bacteria concentrations in stormwater runoff. In this paper, the event mean concentration (EMC) of fecal indicator bacteria (Enterococcus, Escherichia coli, fecal Streptococcus group bacteria, and fecal coliform) across the USA was retrieved from the international stormwater best management practices database to analyze the seasonal variations of inflow and outflow event mean concentrations and removal efficiencies. The Kruskal-Wallis test was employed to determine the seasonal variations of bacteria indicator concentrations and removals, and the two-sample Kolmogorov-Smirnov test was used for comparing different seasonal outcomes. The results indicate that all the inflow EMC of FIB in stormwater runoff is above the water quality criteria. The seasonal differences of fecal Streptococcus group bacteria and fecal coliform are significant. Summer has the potential to increase the bacteria EMC and illustrate the seasonal differences.

  11. Seasonal variation of the temperature profile and its characteristics within urban roughness sublayer

    Institute of Scientific and Technical Information of China (English)

    WANG XiQuani; WANG ZiFa; GUO Hu

    2009-01-01

    By using conventional micro-meteorological observation data of Beijing Yuetan Park Tower (180 m), the temperature profile of urban boundary layer (UBL), its characteristics and seasonal variation are analyzed. The main results are as follows: (1) In winter, the interdiurnal surface air temperature varia-tion at the surface is not synchronized with that of the upper levels, other than in summer and other seasons, which illuminates the impacts of Beijing's geographical location, sky view factor and stably stratified nocturnal inversion. (2) Except that the stratification is unstable around noon, the stratifica-tion in the roof layer or above-roof layer is of seasonal variability, which is weak unstable or weak sta-ble in winter or summer respectively. This weak stable stratification possibly inhibits urban pollutant dispersion upwards in summer season. (3) The effect of urban building rooftop on the UBL thermal state has seasonal difference, that is, the rooftop plays the role of heating or cooling the urban roughness sublayer, in summer or winter respectively, which is similar to the effects of the Qing-hal-Tibet Plateau on the atmospheric thermal state.

  12. Influence of seasonal variation on the phenology and liriodenine content of Annona lutescens (Annonaceae).

    Science.gov (United States)

    Castro-Moreno, Marisol; Tinoco-Ojangurén, Clara Leonor; Cruz-Ortega, Ma Del Rocío; González-Esquinca, Alma Rosa

    2013-07-01

    Annona lutescens Saff. (Annonaceae) grows as a native tree in Chiapas, Mexico in Tropical Dry Forest habitat. Like most Annonaceae, it biosynthesizes benzylisoquinoline alkaloids, mostly liriodenine. To determine the influence of seasonal changes in the accumulation of liriodenine, the monthly variation of liriodenine content in roots, stems and leaves of mature and young trees was observed. These parts of young and mature A. lutescens trees were collected monthly over a 1 year period and the alkaloids were extracted; the liriodenine was quantified by high-resolution liquid chromatography. The phenological stages of the species were also assessed (leaf development, flowering and fruiting) using the Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) scale. The analysis of both young and mature trees showed a significant increase in the liriodenine concentration occurs within roots during the dry season, which coincides with leaf fall. A significant decrease also occurred at the beginning of the rainy season (the period of leaf growth); the liriodenine content for the next rainy season did not reach the levels of the previous dry season. The climatic variation induced phenological and physiological changes in this species.

  13. Long-term and seasonal dynamics of dengue in Iquitos, Peru.

    Directory of Open Access Journals (Sweden)

    Steven T Stoddard

    2014-07-01

    Full Text Available Long-term disease surveillance data provide a basis for studying drivers of pathogen transmission dynamics. Dengue is a mosquito-borne disease caused by four distinct, but related, viruses (DENV-1-4 that potentially affect over half the world's population. Dengue incidence varies seasonally and on longer time scales, presumably driven by the interaction of climate and host susceptibility. Precise understanding of dengue dynamics is constrained, however, by the relative paucity of laboratory-confirmed longitudinal data.We studied 10 years (2000-2010 of laboratory-confirmed, clinic-based surveillance data collected in Iquitos, Peru. We characterized inter and intra-annual patterns of dengue dynamics on a weekly time scale using wavelet analysis. We explored the relationships of case counts to climatic variables with cross-correlation maps on annual and trimester bases.Transmission was dominated by single serotypes, first DENV-3 (2001-2007 then DENV-4 (2008-2010. After 2003, incidence fluctuated inter-annually with outbreaks usually occurring between October and April. We detected a strong positive autocorrelation in case counts at a lag of ∼ 70 weeks, indicating a shift in the timing of peak incidence year-to-year. All climatic variables showed modest seasonality and correlated weakly with the number of reported dengue cases across a range of time lags. Cases were reduced after citywide insecticide fumigation if conducted early in the transmission season.Dengue case counts peaked seasonally despite limited intra-annual variation in climate conditions. Contrary to expectations for this mosquito-borne disease, no climatic variable considered exhibited a strong relationship with transmission. Vector control operations did, however, appear to have a significant impact on transmission some years. Our results indicate that a complicated interplay of factors underlie DENV transmission in contexts such as Iquitos.

  14. Lorenz Curve and Gini coefficient: novel tools for analysing seasonal variation of environmental radon gas.

    Science.gov (United States)

    Groves-Kirkby, C J; Denman, A R; Phillips, P S

    2009-06-01

    Using a methodology derived from Economics, the Lorenz Curve and Gini Coefficient are introduced as tools for investigating and quantifying seasonal variability in environmental radon gas concentration. While the Lorenz Curve presents a graphical view of the cumulative exposure during the course of the time-frame of interest, typically one year, the Gini Coefficient distils this data still further, to provide a single-parameter measure of temporal clustering. Using the assumption that domestic indoor radon concentrations show annual cyclic behaviour, generally higher in the winter months than in summer, published data on seasonal variability of domestic radon concentration levels, in various areas of the UK, Europe, Asia and North America, are analysed. The results demonstrate significantly different annual variation profiles between domestic radon concentrations in different countries and between regions within a country, highlighting the need for caution in ascribing seasonal correction factors to extended geographical areas. The underlying geography, geology and meteorology of a region have defining influences on the seasonal variability of domestic radon concentration, and some examples of potential associations between the Gini Coefficient and regional geological and geographical characteristics are proposed. Similar differences in annual variation profiles are found for soil-gas radon measured as a function of depth at a common site, and among the activity levels of certain radon progeny species, specifically (214)Bi deposited preferentially in human body-fat by decay of inhaled radon gas. Conclusions on the association between these observed measures of variation and potential underlying defining parameters are presented.

  15. Seasonal variation of plankton communities influenced by environmental factors in an artificial lake

    Institute of Scientific and Technical Information of China (English)

    LI Xuemei; YU Yuhe; ZHANG Tanglin; FENG Weisong; AO Hongyi; YAN Qingyun

    2012-01-01

    We evaluated the seasonal variation in plankton community composition in an artificial lake.We conducted microscopic analysis and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified partial 16S rRNA and 18S rRNA genes to characterize the plankton community.The clustering of unweighted pair group method with arithmetic mean (UPGMA) was then used to investigate the similarity of these plankton communities.DGGE fingerprinting revealed that samples collected at the different sites within a season shared high similarity and were generally grouped together.In contrast,we did not observe any seasonal variation based on microscopic analysis.Redundancy analysis (RDA) of the plankton operational taxonomic units (OTUs) in relation to environmental factors revealed that transparency was negatively correlated with the first axis (R=-0.931),and temperature and total phosphorus (TP) were positively correlated with the first axis (R=0.736 and R=0.660,respectively).In conclusion,plankton communities in the artificial lake exhibited significant seasonal variation.Transparency,phosphorus and temperature appear to be the major factors driving the differences in plankton composition.

  16. Seasonal variations of the antioxidant composition in ground bamboo Sasa argenteastriatus leaves.

    Science.gov (United States)

    Ni, Qinxue; Xu, Guangzhi; Wang, Zhiqiang; Gao, Qianxin; Wang, Shu; Zhang, Youzuo

    2012-01-01

    Sasa argenteastriatus, with abundant active compounds and high antioxidant activity in leaves, is a new leafy bamboo grove suitable for exploitation. To utilize it more effectively and scientifically, we investigate the seasonal variations of antioxidant composition in its leaves and antioxidant activity. The leaves of Sasa argenteastriatus were collected on the 5th day of each month in three same-sized sample plots from May 2009 to May 2011. The total flavonoids (TF): phenolics (TP) and triterpenoid (TT) of bamboo leaves were extracted and the contents analyzed by UV-spectrophotometer. Our data showed that all exhibited variations with the changing seasons, with the highest levels appearing in November to March. Antioxidant activity was measured using DPPH and FRAP methods. The highest antioxidant activity appeared in December with the lowest in May. Correlation analyses demonstrated that TP and TF exhibited high correlation with bamboo antioxidant activity. Eight bamboo characteristic compounds (orientin, isoorientin, vitexin, homovitexin and p-coumaric acid, chlorogenic acid, caffeic acid, ferulic acid) were determined by RP-HPLC synchronously. We found that chlorogenic acid, isoorientin and vitexin are the main compounds in Sasa argenteastriatus leaves and the content of isovitexin and chlorogenic acid showed a similar seasonal variation with the TF, TP and TT. Our results suggested that the optimum season for harvesting Sasa argenteastriatus leaves is between autumn and winter.

  17. Seasonal variation of plankton communities influenced by environmental factors in an artificial lake

    Science.gov (United States)

    Li, Xuemei; Yu, Yuhe; Zhang, Tanglin; Feng, Weisong; Ao, Hongyi; Yan, Qingyun

    2012-05-01

    We evaluated the seasonal variation in plankton community composition in an artificial lake. We conducted microscopic analysis and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified partial 16S rRNA and 18S rRNA genes to characterize the plankton community. The clustering of unweighted pair group method with arithmetic mean (UPGMA) was then used to investigate the similarity of these plankton communities. DGGE fingerprinting revealed that samples collected at the different sites within a season shared high similarity and were generally grouped together. In contrast, we did not observe any seasonal variation based on microscopic analysis. Redundancy analysis (RDA) of the plankton operational taxonomic units (OTUs) in relation to environmental factors revealed that transparency was negatively correlated with the first axis ( R=-0.931), and temperature and total phosphorus (TP) were positively correlated with the first axis ( R=0.736 and R=0.660, respectively). In conclusion, plankton communities in the artificial lake exhibited significant seasonal variation. Transparency, phosphorus and temperature appear to be the major factors driving the differences in plankton composition.

  18. Seasonal Variation in Essential oil Composition of Artemisianilagirica var. septentrionalis from Foot Hills of Western Himalaya

    Directory of Open Access Journals (Sweden)

    Rajendra Chandra Padalia

    2014-05-01

    Full Text Available Essential oils composition of the aerial parts of Artemisia nilagirica (Clarke Pamp. var. septentrionalis Pamp. in different seasons viz. spring, summer, rainy, autumn and winter seasons under foot hills agroclimatic conditions of western Himalaya were analyzed and compared by GC–FID and GC–MS. Essential oils were mainly composed of monoterpenoids (59.0%-77.3% and sesquiterpenoids (15.7%-31.6%. The major constituents identified were artemisia ketone (38.3%-61.2%, chrysanthenone (1.5%-7.7%, germacrene D (3.1%-6.8%, β-caryophyllene (1.9%-6.8%, germacra-4,5,10-trien-1-α-ol (1.9%-4.9% and artemisia alcohol (1.4%-3.6%. Compositional analysis showed significant variations in the terpenoid compositions due to seasonal variations. Further, this is for the first time the seasonal variations in essential oil compositions of artemisia ketone rich chemotype of A. nilagirica var. septentrionalis is being reported from India.

  19. Seasonal Variations of the Antioxidant Composition in Ground Bamboo Sasa argenteastriatus Leaves

    Directory of Open Access Journals (Sweden)

    Youzuo Zhang

    2012-02-01

    Full Text Available Sasa argenteastriatus, with abundant active compounds and high antioxidant activity in leaves, is a new leafy bamboo grove suitable for exploitation. To utilize it more effectively and scientifically, we investigate the seasonal variations of antioxidant composition in its leaves and antioxidant activity. The leaves of Sasa argenteastriatus were collected on the 5th day of each month in three same-sized sample plots from May 2009 to May 2011. The total flavonoids (TF: phenolics (TP and triterpenoid (TT of bamboo leaves were extracted and the contents analyzed by UV-spectrophotometer. Our data showed that all exhibited variations with the changing seasons, with the highest levels appearing in November to March. Antioxidant activity was measured using DPPH and FRAP methods. The highest antioxidant activity appeared in December with the lowest in May. Correlation analyses demonstrated that TP and TF exhibited high correlation with bamboo antioxidant activity. Eight bamboo characteristic compounds (orientin, isoorientin, vitexin, homovitexin and p-coumaric acid, chlorogenic acid, caffeic acid, ferulic acid were determined by RP-HPLC synchronously. We found that chlorogenic acid, isoorientin and vitexin are the main compounds in Sasa argenteastriatus leaves and the content of isovitexin and chlorogenic acid showed a similar seasonal variation with the TF, TP and TT. Our results suggested that the optimum season for harvesting Sasa argenteastriatus leaves is between autumn and winter.

  20. Seasonal variation of columnar aerosol optical properties and radiative forcing over Beijing, China

    Science.gov (United States)

    Yu, Xingna; Lü, Rui; Liu, Chao; Yuan, Liang; Shao, Yixing; Zhu, Bin; Lei, Lu

    2017-10-01

    Long-term seasonal characteristics of aerosol optical properties and radiative forcing at Beijing (during March 2001-March 2015) were investigated using a combination of ground-based Sun/sky radiometer retrievals from the AERONET and a radiative transfer model. Aerosol optical depth (AOD) showed a distinct seasonal variation with higher values in spring and summer, and relatively lower values in fall and winter. Average Angstrom exponent (AE) in spring was lower than other seasons, implying the significant impact of dust episodes on aerosol size distribution. AE mainly distributed between 1.0 and 1.4 with an obvious uni-peak pattern in each season. The observation data showed that high AODs (>1.0) were clustered in the fine mode growth wing and the coarse mode. Compared to AOD, seasonal variation in single scattering albedo (SSA) showed an opposite pattern with larger values in summer and spring, and smaller ones in winter and fall. The highest volume size distribution and median radius of fine mode particles occurred in summer, while those of coarse mode particles in spring. The averaged aerosol radiative forcing (ARF) at the top of the atmosphere (TOA) in spring, summer, fall and winter were -33 ± 22 W m-2, -35 ± 22 W m-2, -28 ± 20 W m-2, and -24 ± 23 W m-2 respectively, and these differences were mainly due to the SSA seasonal variation. The largest positive ARF within atmosphere occurred in spring, implying strong warming in the atmosphere. The low heating ratio in summer was caused by the increase in water vapor content, which enhanced light scattering capacity (i.e., increased SSA).

  1. Effects of seasonal and climate variations on calves' thermal comfort and behaviour.

    Science.gov (United States)

    Tripon, Iulian; Cziszter, Ludovic Toma; Bura, Marian; Sossidou, Evangelia N

    2014-09-01

    The aim of this study was to measure the effect of season and climate variations on thermal comfort and behaviour of 6-month-old dairy calves housed in a semi-opened shelter to develop animal-based indicators for assessing animal thermal comfort. The ultimate purpose was to further exploit the use of those indicators to prevent thermal stress by providing appropriate care to the animals. Measurements were taken for winter and summer seasons. Results showed that season significantly influenced (P ≤ 0.01) the lying down behaviour of calves by reducing the time spent lying, from 679.9 min in winter to 554.1 min in summer. Moreover, season had a significant influence (P ≤ 0.01) on feeding behaviour. In detail, the total length of feeding periods was shorter in winter, 442.1 min in comparison to 543.5 min in summer. Time spent drinking increased significantly (P ≤ 0.001), from 11.9 min in winter to 26.9 min in summer. Furthermore, season had a significant influence (P ≤ 0.001) on self grooming behaviour which was 5.5 times longer in duration in winter than in summer (1,336 s vs 244 s). It was concluded that calves' thermal comfort is affected by seasonal and climate variations and that this can be assessed by measuring behaviour with animal-based indicators, such as lying down, resting, standing up, feeding, rumination, drinking and self grooming. The indicators developed may be a useful tool to prevent animal thermal stress by providing appropriate housing and handling to calves under seasonal and climate challenge.

  2. Functional Diversity of Boreal Bog Plant Species Decreases Seasonal Variation of Ecosystem Carbon Sink Function

    Science.gov (United States)

    Korrensalo, A.

    2015-12-01

    Species diversity has been found to decrease the temporal variance of productivity of a plant community, and diversity in species responses to environmental factors seems to make a plant community more stable in changing conditions. Boreal bogs are nutrient poor peatland ecosystems where the number of plant species is low but the species differ greatly in their growth form. In here we aim to assess the role of the variation in photosynthesis between species for the temporal variation in ecosystem carbon sink function. To quantify the photosynthetic properties and their seasonal variation for different bog plant species we measured photosynthetic parameters and stress-inducing chlorophyll fluorescence of vascular plant and Sphagnum moss species in a boreal bog over a growing season. We estimated monthly gross photosynthesis (PG) of the whole study site based on species level light response curves and leaf area development. The estimated PG was further compared with a gross primary production (GPP) estimate measured by eddy covariance (EC) technique. The sum of upscaled PG estimates agreed well with the GPP estimate measured by the EC technique. The contributions of the species and species groups to the ecosystem level PG changed over the growing season. The sharp mid-summer peak in sedge PG was balanced by more stable PG of evergreen shrubs and Sphagna. Species abundance rather than differences in photosynthetic properties between species and growth forms determined the most productive plants on the ecosystem scale. Sphagna had lower photosynthesis and clorophyll fluorescence than vascular plants but were more productive on the ecosystem scale throughout the growing season due to their high areal coverage. These results show that the diversity of growth forms stabilizes the seasonal variation of the ecosystem level PG in an ombrotrophic bog ecosystem. This may increase the resilience of the ecosystem to changing environmental conditions.

  3. Seasonal sediment dynamics shape temperate bedrock reef communities

    Science.gov (United States)

    Figurski, Jared D.; Freiwald, Jan; Lonhart, Steve I.; Storlazzi, Curt

    2016-01-01

    Mobilized seafloor sediment can impact benthic reef communities through burial, scour, and turbidity. These processes are ubiquitous in coastal oceans and, through their influence on the survival, fitness, and interactions of species, can alter the structure and function of benthic communities. In northern Monterey Bay, California, USA, as much as 30% of the seafloor is buried or exposed seasonally, making this an ideal location to test how subtidal temperate rocky reef communities vary in the presence and absence of chronic sediment-based disturbances. Designated dynamic plots were naturally inundated by sediment in summer (50 to 100% cover) and swept clean in winter, whereas designated stable plots remained free of sediment during our study. Multivariate analyses indicated significant differences in the structure of sessile and mobile communities between dynamic and stable reef habitats. For sessile species, community structure in disturbed plots was less variable in space and time than in stable plots due to the maintenance of an early successional state. In contrast, community structure of mobile species varied more in disturbed plots than in stable plots, reflecting how mobile species distribute in response to sediment dynamics. Some species were found only in these disturbed areas, suggesting that the spatial mosaic of disturbance could increase regional diversity. We discuss how the relative ability of species to tolerate disturbance at different life history stages and their ability to colonize habitat translate into community-level differences among habitats, and how this response varies between mobile and sessile communities.

  4. Aerosol Seasonal Variations over Urban-Industrial Regions in Ukraine According to AERONET and POLDER Measurements

    Science.gov (United States)

    Milinevsky, G.; Danylevsky, V.; Bovchaliuk, V.; Bovchaliuk, A.; Goloub, Ph.; Dubovik, O.; Kabashnikov, V.; Chaikovsky, A.; Miatselskaya, N.; Mishchenko, M.; Sosonkin, M.

    2014-01-01

    The paper presents an investigation of aerosol seasonal variations in several urban-industrial regions in Ukraine. Our analysis of seasonal variations of optical and physical aerosol parameters is based on the sun-photometer 2008-2013 data from two urban ground-based AERONET (AErosol RObotic NETwork) sites in Ukraine (Kyiv, Lugansk) as well as on satellite POLDER instrument data for urban-industrial areas in Ukraine. We also analyzed the data from one AERONET site in Belarus (Minsk) in order to compare with the Ukrainian sites. Aerosol amount and optical depth (AOD) values in the atmosphere columns over the large urbanized areas like Kyiv and Minsk have maximum values in the spring (April-May) and late summer (August), whereas minimum values are observed in late autumn. The results show that fine-mode particles are most frequently detected during the spring and late summer seasons. The analysis of the seasonal AOD variations over the urban-industrial areas in the eastern and central parts of Ukraine according to both ground-based and POLDER data exhibits the similar traits. The seasonal variation similarity in the regions denotes the resemblance in basic aerosol sources that are closely related to properties of aerosol particles. The behavior of basic aerosol parameters in the western part of Ukraine is different from eastern and central regions and shows an earlier appearance of the spring and summer AOD maxima. Spectral single-scattering albedo, complex refractive index and size distribution of aerosol particles in the atmosphere column over Kyiv have different behavior for warm (April-October) and cold seasons. The seasonal features of fine and coarse aerosol particle behavior over the Kyiv site were analyzed. A prevailing influence of the fine-mode particles on the optical properties of the aerosol layer over the region has been established. The back-trajectory and cluster analysis techniques were applied to study the seasonal back trajectories and prevailing

  5. SEASONAL VARIATIONS IN GROUNDWATER QUALITY OF VALSAD DISTRICT OF SOUTH GUJARAT (INDIA

    Directory of Open Access Journals (Sweden)

    P. Shroff

    2015-05-01

    Full Text Available Groundwater is an important precious natural resource. For optimum utilization of water resources, it is necessary to know both the quality as well as quantity of water. The present investigation is focused on seasonal variation in groundwater quality of Valsad district of south Gujarat (India. Groundwater samples from fifteen sampling stations were collected for two year i.e. from Aug 2007 to July 2009 and analyzed for pH, Colour, Total Hardness (TH, Calcium (Ca, Magnesium (Mg, Total Alkalinity (TA, Chloride and Sodium. Marginally higher level was observed in almost all parameters in summer season. No significant change observed in pH, Colour and Calcium.

  6. [Seasonal variation of functional diversity of aquatic microbial community in Apostichopus japonicus cultural pond].

    Science.gov (United States)

    Yan, Fa-Jun; Tian, Xiang-Li; Dong, Shuang-Lin; Yang, Gang

    2014-05-01

    The functional diversity of aquatic microbial communities in sea cucumber (Apostichopus japonicus) cultural ponds was examined in this paper. The Biolog plate technique and redundancy analysis (RDA) method were used to evaluate seasonal changes and their relationships with environmental factors. The results showed that both total amount and types of carbon sources utilized by microbes in the sea cucumber cultural ponds varied seasonally, and were the highest in summer and lowest in winter, with polymers being the main type of carbon sources. Principal component analysis revealed that the carbon utilization diversity of the microbial communities varied significantly over the seasonal courses. A total of 10 categories of carbon sources were significantly related to the principal component 1, among which were polymers, carbohydrates, carboxylic acids, amino acids, and amines. Significant seasonal changes were detected for all carbon utilization diversity indices of the microbial communities, including Shannon, McIntosh, Simpson, and S-E. However, seasonal variations were different among the microbial diversity indices. RDA analysis revealed that TP, NO(3-)-N, TN, and PO4(3-)-P were the critical environmental factors influencing the seasonal changes in functional diversity of aquatic microbial community in sea cucumber cultural ponds.

  7. Seasonal variation in kangaroo tooth enamel oxygen and carbon isotopes in southern Australia

    Science.gov (United States)

    Brookman, Tom H.; Ambrose, Stanley H.

    2012-09-01

    Serial sampling of tooth enamel growth increments for carbon and oxygen isotopic analyses of Macropus (kangaroo) teeth was performed to assess the potential for reconstructing paleoseasonality. The carbon isotope composition of tooth enamel apatite carbonate reflects the proportional intake of C3 and C4 vegetation. The oxygen isotopic composition of enamel reflects that of ingested and metabolic water. Tooth enamel forms sequentially from the tip of the crown to the base, so dietary and environmental changes during the tooth's formation can be detected. δ13C and δ18O values were determined for a series of enamel samples drilled from the 3rd and 4th molars of kangaroos that were collected along a 900 km north-south transect in southern Australia. The serial sampling method did not yield pronounced seasonal isotopic variation patterns in Macropus enamel. The full extent of dietary isotopic variation may be obscured by attenuation of the isotopic signal during enamel mineralisation. Brachydont (low-crowned) Macropus teeth may be less sensitive to seasonal variation in isotopic composition due to time-averaging during mineralisation. However, geographic variations observed suggest that there may be potential for tracking latitudinal shifts in vegetation zones and seasonal environmental patterns in response to climate change.

  8. Seasonal variations in red deer (Cervus elaphus) hematology related to antler growth and biometrics measurements.

    Science.gov (United States)

    Gaspar-López, Enrique; Landete-Castillejos, Tomás; Estevez, Jose Antonio; Ceacero, Francisco; Gallego, Laureano; García, Andrés Jose

    2011-04-01

    The aim of the study was to relate seasonal hematology changes with the rest of physiological variations suffered by red deer, such as antler and biometrics cycle, and to assess the relationship between hematology and the effort performed in antler development. Blood samples were taken from 21 male red deer every 4 weeks during 18 months. Samples were analyzed for the main hematological parameters. Simultaneously, biometrics measurements were taken, such as antler length, body weight, body condition score, testicular diameter (TD), and thoracic and neck girth. All the blood cell types (erythrocytes, leukocytes, and platelets) showed seasonal variations, increasing as antler cleaning approached, as did hematocrit and hemoglobin. The final size of antlers was negatively related to leukocyte count, nonlymphoid leukocyte count, red cell distribution width, mean corpuscular hemoglobin, mean platelet volume, and TD, whereas it was positively related to body condition during antler growth. Huge seasonal variations in some hematological values have been found to be related to changes in antler and biometrics measurements. Since these variations are even greater than the caused by deer handling, they should be taken into account when evaluating hematology in deer populations.

  9. The epidemiology of acute appendicitis in California: racial, gender, and seasonal variation.

    Science.gov (United States)

    Luckmann, R; Davis, P

    1991-09-01

    The incidence of acute appendicitis has been reported to vary substantially by country, geographic region, race, sex, season, and occupation, but the reasons for this variation are unknown. We evaluated several risk factors for appendicitis by analyzing data from hospital discharge abstracts on all cases of acute appendicitis treated surgically in nonfederal hospitals in California from 1983 to 1986 (N = 102,546). Comparison of age and sex-specific incidence rates for four racial/ethnic groups (white, Hispanic, black, and Asian/other) revealed rates in blacks and the Asian/other group one-half or less of the rates for whites and Hispanics between the ages of 5 and 29 years. Incidence rates in males were higher than rates in females in all racial/ethnic groups for most ages (RR = 1.1-1.7). Seasonal variation in incidence was modest. Peak rates occurred in July, August, and September, and the lowest rates occurred in December. Hypotheses about the etiology of appendicitis must account for substantial racial/ethnic, gender, age variation, and modest seasonal variation in the incidence.

  10. Spatial variation in Earth structure inferred by GNSS seasonal deformations due to snow loads in northeast Japan

    Science.gov (United States)

    Hirose, H.; Kurisu, R.; Nishimura, T.

    2016-12-01

    Seasonal variations are observed in GNSS site coordinate time series (e.g., Murakami and Miyazaki, 2001; Munekane et al., 2004). Heki (2001) showed that snow loads cause seasonal subsidence in winter in the Tohoku region, northeast Japan from the Geospatial Information Authority of Japan's GEONET GNSS daily site coordinates during the period 1999.0-2001.0. It becomes worth reevaluating this issue because the observed GNSS data are accumulated over 10 years and the amplitude of apparent seasonal components can be reduced with revised analysis strategies (e.g., Nakagawa et al., 2009). Here we show that the correlation between a seasonal variation in GNSS vertical displacement time-series and snow depth measured by Japan Meteorological Agency's AMeDAS over 10 years is good in some areas with the largest snow depths among the study areas, the ratio of seasonal subsidence to snow depth shows spatial variation, and the variation can be explained by spatial variation of underground structure.

  11. Two distinct patterns of seasonal variation of airborne black carbon over Tibetan Plateau

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Mo; Xu, Baiqing; Wang, Ninglian; Cao, Junji; Tie, Xuexi; Wang, Hailong; Zhu, Chongshu; Yang, Wei

    2016-12-01

    Airborne black carbon (BC) mass concentrations were measured from November 2012 to June 2013 at Ranwu and Beiluhe, located in the southeastern and central Tibetan Plateau, respectively. Monthly mean BC concentrations showawinter (November–February) high (413.2 ng m$-$3) and spring (March–June) low(139.1 ng m$-$3) at Ranwu, but in contrast awinter lowand spring high at Beiluhe (204.8 and 621.6 ng m$-$3, respectively). By examining the meteorological conditions at various scales, we found that themonthly variation of airborne BC over the southeastern Tibetan Plateau (TP) was highly influenced by regional precipitation and over the hinterland by winds. Local precipitation at both sites showed little impact on the seasonal variation of airborne BC concentrations. Potential BC source regions are identified using air mass backward trajectory analysis. At Ranwu, BC was dominated by the air masses from the northeastern India and Bangladesh in both winter and spring, whereas at Beiluhe it was largely contributed by air masses from the south slope of Himalayas in winter, and from the arid region in the north of the TP in spring. Thewinter and spring seasonal peak of BC in the southern TP is largely contributed by emissions from South Asia, and this seasonal variation is heavily influenced by the regional monsoon. In the northern TP, BC had high concentrations during spring and summer seasons, which is very likely associated with more efficient transport of BC over the arid regions on the north of Tibetan Plateau and in Central Asia. Airborne BC concentrations at the Ranwusampling site showed a significant diurnal cyclewith a peak shortly after sunrise followed by a decrease before noon in both winter and spring, likely shaped by local human activities and the diurnal variation of wind speed. At the Beiluhe sampling site, the diurnal variation of BC is different and less distinct.

  12. Adventitious rhizogenesis in Bambusa nutans and Bambusa tulda: Influence of seasonal variation, IBA and cutting type

    Institute of Scientific and Technical Information of China (English)

    S. Singh; S. Yadav; P. K. Patel; S.A.Ansari

    2011-01-01

    The influence of seasonal variation,indole-3-butyric acid (IBA) and type of cuttings wasexamined on induction and growth of adventitious roots in Bambusa nutans Wall.and Bambusa tulda Roxb.Singlenode culm and culm-branch cuttings from the mature culms were provided with immersion treatment for 24 h of either water (control) or 2 mM IBA in four different seasons,i.e.,spring (mid February),summer (mid May),rainy (mid July),and winter (mid November) and maintained for two months in the mist chamber at the relative humidity of (70±5)%and the temperature of (30±2)℃.In B.nutans,adventitious rooting occuffed in both types of cuttings in all the seasons with the best rooting in the summer season i.e.,May (88% in culm cuttings) and the least in winter.On the contrary,adventitious rooting was recorded only in culm cuttings in spring and summer season in B.tulda.IBA treatment significantly enhanced rooting,root number and root length; registering 14 to 17 times improvement over control in the best rooting season.Three factor- interactions (season × cutting type × IBA treatment) were significant for rooting in B.nutans and all characteristics,except sprouting in B.tulda.Thus,single-node culm and culm-branch cuttings in B.nutans and culm cuttings in B.tulda treated with 2 mM IBA during spring (February)to summer (May) season are recommended for their clonal multiplication.

  13. Seasonal variation in accumulation of persistent organic pollutants in an Arctic marine benthic food web

    Energy Technology Data Exchange (ETDEWEB)

    Evenset, A., E-mail: anita.evenset@akvaplan.niva.no [Akvaplan-niva. Fram Centre, Tromsø (Norway); University of Tromsø, The Arctic University of Norway, Tromsø (Norway); Hallanger, I.G. [University of Tromsø, The Arctic University of Norway, Tromsø (Norway); Tessmann, M. [Akvaplan-niva. Fram Centre, Tromsø (Norway); Institute for Hydrobiology and Fisheries Research, University of Hamburg (Germany); Warner, N. [Norwegian Institute for Air Research, Fram Centre, Tromsø (Norway); Ruus, A. [Norwegian Institute for Water Research, Oslo (Norway); Borgå, K. [Norwegian Institute for Water Research, Oslo (Norway); Department of Biosciences, P.O. Box 1066, Blindern 0316, Oslo (Norway); Gabrielsen, G.W. [Norwegian Polar Institute, Fram Centre, Tromsø (Norway); Christensen, G. [Akvaplan-niva. Fram Centre, Tromsø (Norway); Renaud, P.E. [Akvaplan-niva. Fram Centre, Tromsø (Norway); University Centre in Svalbard, Longyearbyen (Norway)

    2016-01-15

    The aim of the present study was to investigate seasonal variation in persistent organic pollutant (POP) concentrations, as well as food-web biomagnification, in an Arctic, benthic marine community. Macrozoobenthos, demersal fish and common eiders were collected both inside and outside of Kongsfjorden, Svalbard, during May, July and October 2007. The samples were analysed for a selection of legacy chlorinated POPs. Overall, low levels of POPs were measured in all samples. Although POP levels and accumulation patterns showed some seasonal variation, the magnitude and direction of change was not consistent among species. Overall, seasonality in bioaccumulation in benthic biota was less pronounced than in the pelagic system in Kongsfjorden. In addition, the results indicate that δ{sup 15}N is not a good predictor for POP-levels in benthic food chains. Other factors, such as feeding strategy (omnivory, necrophagy versus herbivory), degree of contact with the sediment, and a high dependence on particulate organic matter (POM), with low POP-levels and high δ{sup 15}N-values (due to bacterial isotope enrichment), seem to govern the uptake of the different POPs and result in loads deviating from what would be expected consulting the trophic position alone. - Highlights: • Seasonal variation in POP biomagnification was investigated in a benthic food web. • Levels of POPs are generally low in benthic species from Kongsfjorden, Svalbard. • POP-concentrations varied with season, but direction of change varied among taxa. • No POP-biomagnification, except for cis-nonachlor, was detected in this study. • δ{sup 15}N-values does not seem to be a good proxy for trophic level in macrozoobenthos.

  14. Comparative Analysis of Seasonal Variation in Tropospheric Nitrogen Dioxide over Pakistan and Saudi Arabia

    Science.gov (United States)

    Fahim Khokhar, Muhammad; Wagner, Thomas; Jamil, Mohsin

    2016-07-01

    In this study, spatial and temporal distributions of tropospheric NO2 vertical column densities over Pakistan and Saudi Arabia during the time period of 2004-2015 are discussed. Data products from the satellite instrument OMI are used. The results show a large NO2 growth over major cities of both countries, particularly the areas with rapid urbanization. Different seasonal cycles were observed over both countries. Especially, seasonal variation in tropospheric NO2 over Pakistan is largely impacted by the photolysis rate, OH radical and monsoon rains in addition to soil emissions, agriculture fires and other anthropogenic activities. While in the case of Saudi Arabia, the seasonal variation in tropospheric NO2 is completely driven by thermal power generation. Furthermore, different regions of Pakistan exhibited different seasonal trends. In the provinces of Punjab (north-east), Khyber Paktunkhwa (north-west) and Sindh (south-east), NO2 columns are maximum in winter and minimum in summer months while a reversed seasonality was observed in the province of Baluchistan (south-west). We compared the observed Spatio-temporal patterns to existing emission inventories and found that for the most populated provinces the NOx emissions are clearly dominated by anthropogenic sources. In these areas also the strongest positive trends were observed. NOx released from soils and produced by lightning both together contribute about 20% for the provinces of Punjab, Sindh, and Khyber Pakhtunkhwa, while its contribution in Baluchistan is much stronger (~50%). NOx emissions from biomass burning are negligible. This finding can also explain the observed summer maximum in Baluchistan since the highest lightning activity occurs during the Monsoon season. Our comparison also indicates that the inventories of anthropogenic NOx emissions over Pakistan seem to underestimate the true emissions by about a factor of two.

  15. Seasonal and interannual variations of flow discharge from Pearl River into sea

    Directory of Open Access Journals (Sweden)

    Wei ZHANG

    2012-12-01

    Full Text Available Flow discharge from the river basin into the sea has severe impacts on the immediate vicinity of river channels, estuaries, and coastal areas. This paper analyzes the features and temporal trends of flow discharge at Pearl River’s three main gauge stations: the Wuzhou, Shijiao, and Boluo gauge stations on the West River, North River, and East River, respectively. The results show no significant trend in annual mean discharge into the sea at the three gauge stations. Changes of monthly mean discharge at the Boluo Gauge Station are evident, and a majority of monthly discharge in the dry season displays significant increasing trends. Furthermore, changes of the extreme discharge are quite evident, with a significant decreasing trend in the annual maximum discharge and a significant increasing trend in the minimum one. The significantly decreasing ratio of the flood discharge to annual discharge at the Boluo Gauge Station indicates that the flow discharge from the East River has increased in the dry season and decreased in the flood season since the construction of dams and reservoirs. At the other two gauge stations, the Wuzhou and Shijiao gauge stations, the seasonal discharge generally does not change perceptibly. Human impacts, especially those pertaining to reservoir and dam construction, appear to be responsible for the seasonal variation of flow discharge. The results indicate that the construction and operation of dams and reservoirs in the East River have a greater influence on flow discharge, which can well explain why the seasonal variation of flow discharge from the East River is more evident.

  16. Variational principles for stochastic soliton dynamics.

    Science.gov (United States)

    Holm, Darryl D; Tyranowski, Tomasz M

    2016-03-01

    We develop a variational method of deriving stochastic partial differential equations whose solutions follow the flow of a stochastic vector field. As an example in one spatial dimension, we numerically simulate singular solutions (peakons) of the stochastically perturbed Camassa-Holm (CH) equation derived using this method. These numerical simulations show that peakon soliton solutions of the stochastically perturbed CH equation persist and provide an interesting laboratory for investigating the sensitivity and accuracy of adding stochasticity to finite dimensional solutions of stochastic partial differential equations. In particular, some choices of stochastic perturbations of the peakon dynamics by Wiener noise (canonical Hamiltonian stochastic deformations, CH-SD) allow peakons to interpenetrate and exchange order on the real line in overtaking collisions, although this behaviour does not occur for other choices of stochastic perturbations which preserve the Euler-Poincaré structure of the CH equation (parametric stochastic deformations, P-SD), and it also does not occur for peakon solutions of the unperturbed deterministic CH equation. The discussion raises issues about the science of stochastic deformations of finite-dimensional approximations of evolutionary partial differential equation and the sensitivity of the resulting solutions to the choices made in stochastic modelling.

  17. Dynamics and Transit Variations of Resonant Exoplanets

    Science.gov (United States)

    Nesvorný, David; Vokrouhlický, David

    2016-06-01

    Transit timing variations (TTVs) are deviations of the measured midtransit times from the exact periodicity. One of the most interesting causes of TTVs is the gravitational interaction between planets. Here we consider a case of two planets in a mean motion resonance (orbital periods in a ratio of small integers). This case is important because the resonant interaction can amplify the TTV effect and allow planets to be detected more easily. We develop an analytic model of the resonant dynamics valid for small orbital eccentricities and use it to derive the principal TTV terms. We find that a resonant system should show TTV terms with two basic periods (and their harmonics). The resonant TTV period is proportional (m/M *)-2/3, where m and M * are the planetary and stellar masses. For m = 10-4 M *, for example, the TTV period exceeds the orbital period by about two orders of magnitude. The amplitude of the resonant TTV terms scales linearly with the libration amplitude. The ratio of the TTV amplitudes of two resonant planets is inversely proportional to the ratio of their masses. These and other relationships discussed in the main text can be used to aid the interpretation of TTV observations.

  18. Dynamics and Transit Variations of Resonant Exoplanets

    CERN Document Server

    Nesvorny, D

    2016-01-01

    The Transit Timing Variations (TTVs) are deviations of the measured mid-transit times from the exact periodicity. One of the most interesting causes of TTVs is the gravitational interaction between planets. Here we consider a case of two planets in a mean motion resonance (orbital periods in a ratio of small integers). This case is important because the resonant interaction can amplify the TTV effect and allow planets to be detected more easily. We develop an analytic model of the resonant dynamics valid for small orbital eccentricities and use it to derive the principal TTV terms. We find that a resonant system should show TTV terms with two basic periods (and their harmonics). The resonant TTV period is proportional (m/M_*)^(-2/3), where m and M_* are the planetary and stellar masses. For m=10^(-4) M_*, for example, the TTV period exceeds the orbital period by ~2 orders of magnitude. The amplitude of the resonant TTV terms scales linearly with the libration amplitude. The ratio of the TTV amplitudes of two ...

  19. Seasonal variations of radon concentrations in single-family houses with different sub-structures

    DEFF Research Database (Denmark)

    Majborn, B.

    1992-01-01

    Seasonal variations of indoor radon concentrations have been studied in 70 single-family houses selected according to the type of sub-structure and the type of soil underneath the house. Five categories of sub-structure were included - slab-on-grade, crawl space, basement, and combinations...... of basement with slab-on-grade or crawl space. Half of the houses are located on clayey till and the other half on glaciofluvial gravel. In each house radon was measured in a living room and a bedroom, in the basement if present, and in the crawl space if present and accessible. The measurements were made...... with track detectors on a quarterly basis throughout a year. For living rooms and bedrooms the seasonal variations range from being highly significant for the slab-on-grade houses to being insignificant for the crawl space houses. For basements and crawl spaces the geometric mean radon concentrations do...

  20. Seasonal variations in the antioxidant defence systems and lipid peroxidation of the digestive gland of mussels.

    Science.gov (United States)

    Viarengo, A; Canesi, L; Pertica, M; Livingstone, D R

    1991-01-01

    1. The seasonal variations in the level of antioxidant compounds (glutathione (GSH), vitamin E, carotenoids) and in the activity of antioxidant enzymes, superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), GSH-peroxidase (EC 1.11.1.9) in the digestive gland of mussels (Mytilus sp.) were evaluated. The lipid peroxidation process was also measured by determining the tissue concentration of malondialdehyde (MDA). 2. The physiological fluctuations of the antioxidant defence systems were inversely related to the accumulation of lipid peroxidation products (MDA) in the tissue. The observed seasonal variations are presumably related to the changing metabolic status of the animals, itself dependent on such factors as gonad ripening and food availability. 3. In particular, the obtained data indicate that a reduction of the antioxidant defence systems, occurring during winter, could be directly responsible for an enhanced susceptibility of mussels tissues to oxidative stress, as indicated by the high MDA concentration observed in this period.

  1. Seasonal and pollution-induced variations in biomarkers of transplanted mussels within the Beagle Channel.

    Science.gov (United States)

    Giarratano, Erica; Gil, Mónica N; Malanga, Gabriela

    2011-06-01

    The occurrence of biomarker variations linked to environmental factors makes it difficult to distinguish the effect of pollution. In an attempt to evaluate spatial and seasonal effects of environmental parameters on biomarker responses, mussels Mytilus edulis chilensis coming from an aquaculture farm were transplanted to several points within Ushuaia Bay (Beagle Channel) for 6 weeks in summer and winter. Activities of superoxide dismutase, catalase, glutathione-S-transferase and levels of lipid peroxidation were measured in gills and digestive gland. Cu, Zn, Fe, Cd and Pb concentrations were also assessed. Results indicated a significant effect of seasons on biological responses as well as in metal bioaccumulation showing the influence of natural factors such as dissolved oxygen, temperature and food availability. The interdependence of those environmental factors is important for the homeostasis of thermoconformers, especially regarding their oxidative metabolism and should also be taken into consideration to distinguish natural from pollution-induced variations. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Seasonal variation in bioaerosol exposure during biowaste collection and measurements of leaked percolate

    DEFF Research Database (Denmark)

    Nielsen, Birgitte Herbert; Nielsen, Eva Møller; Breum, Niels O.

    2000-01-01

    /compactor truck (P/C) and paper sack/platform truck (P/P). The maximum personal exposure was found to occur during the summer at the following median levels: total microorganisms 9.2 x 10(5) cells m(-3), culturable fungi (moulds) 7.8 x 10(4) cfu m(-3), Aspergillus fumigatus 2.9 x 10(-3) cfu m(3), mesophilic...... actinomycetes 9.0 x 10(2) cfu m(-3), bacteria 1.0 x 10(4) cfu m(-3), endotoxin 16 EU m(-3) (1.0 ng m(-3)) and dust 0.33 mg m(-3). A seasonal variation was observed for microorganisms, moulds, A. fumigatus, mesophilic actinomycetes and endotoxin (P ....2 to 2.3 x 10(9) cfu ml(-1)). A seasonal variation was observed for concentrations of total microorganisms, moulds and endotoxin with a maximum occurring during the summer (P

  3. Seasonal variations in maternal mortality in Maputo, Mozambique: the role of malaria.

    Science.gov (United States)

    Romagosa, Cleofé; Ordi, Jaume; Saute, Francisco; Quintó, Llorenç; Machungo, Fernanda; Ismail, Mamudo R; Carrilho, Carla; Osman, Nafissa; Alonso, Pedro L; Menendez, Clara

    2007-01-01

    To evaluate the impact of malaria on maternal death through the analysis of the seasonal variations of crude and malaria-specific maternal mortality rates. All maternal deaths and live births occurring at Maputo Central Hospital, located in an urban area, between January 2001 and December 2003, were retrospectively recorded. Clinical diagnoses of the causes of death and period of the year were analysed. Two hundred and seventy-eight deaths were recorded. The overall crude maternal mortality rate was 995/100 000 live births. Malaria was the most frequent cause of maternal death, accounting for 23%. Crude and malaria-specific maternal mortality rates showed a similar pattern of seasonal variation, with peaks at the beginning and the end of the malaria transmission season. The malaria-specific maternal mortality rate was significantly higher during the rainy seasons (rate ratio 1.919; 95% CI 1.061, 3.470; P = 0.031). Malaria may contribute to maternal mortality in highly endemic countries in sub-Saharan Africa, at least in urban areas. Efforts to improve malaria control in pregnancy may have an impact on maternal mortality in sub-Saharan Africa.

  4. Seasonal variation of methylmercury in sediment cores from the Tagus Estuary (Portugal).

    Science.gov (United States)

    Monteiro, Carlos Eduardo; Cesário, Rute; O'Driscoll, Nelson J; Nogueira, Marta; Válega, Mónica; Caetano, Miguel; Canário, João

    2016-03-15

    Seasonal and spatial variations of dissolved and particulate methylmercury were evaluated for the first time in sediment cores from the Tagus Estuary. Results showed the highest MeHg concentrations in summer months indicating that the "seasonally" methylation process occurs not only at the topmost layers of the sediments but also in the deeper layers of the sediment column. The proportion of MeHg (up to 92%) in some of our pore water samples was higher than values reported in the literature for other estuaries suggesting that the sedimentary environment in the Tagus tends to favour Hg methylation. This work points to the importance of seasonal variation of the MeHg production in sediment cores. In physically dominated estuaries this enhances seasonal MeHg production in deeper sediments that can have serious ecological impacts due to resuspension or advection processes under extreme events by the increase of MeHg transported to the water column. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Seasonal lipid dynamics of herring and sprat in the Baltic Sea and possible implications for cod reproduction

    DEFF Research Database (Denmark)

    Røjbek, Maria; Tomkiewicz, Jonna; Støttrup, Josianne

    increased dramatically in the early 1990ies. Thechanges in plankton communities in combination with increased competition resulted indeclined condition of clupeids. Polyunsaturated fatty acids originate from phytoplankton andare transmitted through the food web. The present study investigates.......47% in March and 9.60% in June. The lipid content inherring also varied within season but was lower than sprat: 7.42% in November, 6.71% inJanuary and 4.70% in March. The seasonal lipid dynamic was reflected in variation of specific fatty acids. Clupeids are the major prey of Baltic cod so deficiencies...

  6. Estuarine Nitrogen Dynamics Along the Alaskan Beaufort Sea Coast: Seasonal Patterns and Potential Climate Change Effects

    Science.gov (United States)

    McClelland, J. W.; Connelly, T. L.; Crump, B. C.; Kellogg, C.; Dunton, K. H.

    2014-12-01

    Seasonal runoff and sea-ice cover create highly dynamic estuarine conditions in the Arctic. Studies focusing on major systems such as the Mackenzie have demonstrated how these variables interact to influence nutrient supply and uptake dynamics. Far less is known about the seasonality of smaller estuarine systems in the Arctic. Data collected from lagoons along the eastern Alaska Beaufort Sea coast show that salinities range from near zero in the spring to as high as 50 in the winter. Runoff and sea-ice thaw in the spring create highly stratified conditions, with hyper-saline bottom waters persisting through the summer in some locations. These variations in physical conditions are accompanied by variations in nitrogen availability within the lagoons. High concentrations of ammonium, and to a lesser extent nitrate, build up under the ice during the winter months. These nutrients are rapidly depleted during the ice break-up period and remain low throughout the summer. Concentrations of organic nitrogen, on the other hand, peak during the ice break-up period. While river inputs contribute directly to this nitrogen peak through the supply of land-derived organic matter, fatty acid markers also show that locally produced organic matter (primarily diatoms) peaks during the ice break-up period. Seasonal changes in nitrogen are accompanied by distinct shifts in microbial community composition as well as changes in stable isotope values of metazoan consumers. Changes in climate that are altering both runoff and sea-ice have the potential to influence the quantity and timing of nutrient availability and associated biological production in arctic coastal waters.

  7. Seasonal variation of technetium-99 in Fucus vesiculosus and its application as an oceanographic tracer

    DEFF Research Database (Denmark)

    Shi, Keliang; Hou, Xiaolin; Roos, Per

    2013-01-01

    The concentration of 99Tc was determined in archived time series seaweed samples collected at Klint (Denmark). The results demonstrate a significantly seasonal variation of 99Tc concentrations in Fucus vesiculosus with maximum values in winter and minimum values in summer. The mechanism driving t...... of (1.9 0.5) 105 L/kg, were obtained. This indicates that F. vesiculosus can be used as a reliable bioindicator to monitor 99Tc concentration in seawater....

  8. Trend, seasonal and diurnal variations of atmospheric CO2 in Beijing

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The concentration of atmospheric CO2 in Beijing increased rapidly at a mean growth rate of 3.7%@a?1 from 1993 to 1995. After displaying a peak of (409.7±25.9) ?mol@mol?1 in 1995, it decreased slowly. Both the almost stable anthropogenic CO2 source and increasing biotic CO2 sink contribute to the drop of CO2 concentration from 1995 to 2000. The seasonal variation of CO2 concentration exhibits a clear cycle with a maximum in winter, averaging (426.8±20.6) ?mol@mol?1, and a minimum in summer, averaging (369.1±6.1) ?mol@mol?1. The seasonal variation of CO2 concentration is mainly controlled by phenology. The mean diurnal variation of atmospheric CO2 concentration for a year in Beijing is highly clear: daily maximum CO2 concentration usually occurs at night, but daily minimum CO2 concentration does in the daytime, with a mean diurnal difference more than 34.7 ?mol@mol?1. It has been revealed that the interannual variations of atmospheric CO2 concentration in winter and autumn regulated the interannual trend of atmospheric CO2, whereas the interannual variation of CO2 concentration in summer affected the general tendency of atmospheric CO2 in a less degree.

  9. Altitudinal and seasonal variations in the diet of Japanese macaques in Yakushima.

    Science.gov (United States)

    Hanya, Goro; Noma, Naohiko; Agetsuma, Naoki

    2003-01-01

    Altitudinal and seasonal variations in the diet of Japanese macaques in Yakushima, southwestern Japan, were studied for 2 years by means of fecal analysis. The altitudinal range of fecal samples collected was 30 m to 1,203 m above sea level, and it was divided into three zones: low-zone forest (0-399 m), middle-zone forest (400-799 m), and high-zone forest (800 m-1,230 m). There was a considerable altitudinal and seasonal variation in the macaques' diet. Seed/fruit and animal matter were eaten more in the lower zones, whereas more fiber and fungi were consumed in the higher zones. In all of the zones, they ate seed/fruits the most in autumn (September-November) and the least in spring (March-April). They ate fibrous food the most in spring and the least in autumn. Macaques relied on seed/fruits heavily in the lower zone for a longer period than in the higher zones. Macaques in the high-zone forest ate almost no seed/fruit foods from March to May. Altitudinal variations in availability of seed/fruit foods seem to have influenced the altitudinal variations in diet. Total basal area of seed/fruit-food trees, species richness of seed/fruit-foods, main seed/fruit-food types available, and annual fleshy-fruit production all decreased with increasing altitude. Both interannual variation and annual cyclicity of diet were found in all zones.

  10. Variations in abundance, diversity and community composition of airborne fungi in swine houses across seasons.

    Science.gov (United States)

    Kumari, Priyanka; Woo, Cheolwoon; Yamamoto, Naomichi; Choi, Hong-Lim

    2016-11-28

    We examined the abundance, diversity and community composition of airborne fungi in swine houses during winter and summer seasons by using quantitative PCR and Illumina HiSeq sequencing of ITS1 region. The abundance of airborne fungi varied significantly only between seasons, while fungal diversity varied significantly both within and between seasons, with both abundance and diversity peaked in winter. The fungal OTU composition was largely structured by the swine house unit and season as well as by their interactions. Of the measured microclimate variables, relative humidity, particulate matters (PMs), ammonia, and stocking density were significantly correlated with fungal OTU composition. The variation in beta diversity was higher within swine houses during summer, which indicates that the airborne fungal community composition was more heterogeneous in summer compared to winter. We also identified several potential allergen/pathogen related fungal genera in swine houses. The total relative abundance of potential allergen/pathogen related fungal genera varied between swine houses in both seasons, and showed positive correlation with PM2.5. Overall, our findings show that the abundance, diversity and composition of airborne fungi are highly variable in swine houses and to a large extent structured by indoor microclimate variables of swine houses.

  11. Variations in abundance, diversity and community composition of airborne fungi in swine houses across seasons

    Science.gov (United States)

    Kumari, Priyanka; Woo, Cheolwoon; Yamamoto, Naomichi; Choi, Hong-Lim

    2016-11-01

    We examined the abundance, diversity and community composition of airborne fungi in swine houses during winter and summer seasons by using quantitative PCR and Illumina HiSeq sequencing of ITS1 region. The abundance of airborne fungi varied significantly only between seasons, while fungal diversity varied significantly both within and between seasons, with both abundance and diversity peaked in winter. The fungal OTU composition was largely structured by the swine house unit and season as well as by their interactions. Of the measured microclimate variables, relative humidity, particulate matters (PMs), ammonia, and stocking density were significantly correlated with fungal OTU composition. The variation in beta diversity was higher within swine houses during summer, which indicates that the airborne fungal community composition was more heterogeneous in summer compared to winter. We also identified several potential allergen/pathogen related fungal genera in swine houses. The total relative abundance of potential allergen/pathogen related fungal genera varied between swine houses in both seasons, and showed positive correlation with PM2.5. Overall, our findings show that the abundance, diversity and composition of airborne fungi are highly variable in swine houses and to a large extent structured by indoor microclimate variables of swine houses.

  12. Seasonal variation of fecal contamination in drinking water sources in developing countries: a systematic review.

    Science.gov (United States)

    Kostyla, Caroline; Bain, Rob; Cronk, Ryan; Bartram, Jamie

    2015-05-01

    Accounting for fecal contamination of drinking water sources is an important step in improving monitoring of global access to safe drinking water. Fecal contamination varies with time while its monitoring is often infrequent. We sought to understand seasonal trends in fecal contamination to guide best practices to capture seasonal variation and ascertain the extent to which the results of a single sample may overestimate compliance with health guidelines. The findings from 22 studies from developing countries written in English and identified through a systematic review were analyzed. Fecal contamination in improved drinking water sources was shown to follow a statistically significant seasonal trend of greater contamination during the wet season (p<0.001). This trend was consistent across fecal indicator bacteria, five source types, twelve Köppen-Geiger climate zones, and across both rural and urban areas. Guidance on seasonally representative water quality monitoring by the World Health Organization and national water quality agencies could lead to improved assessments of access to safe drinking water. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Multivariate statistical techniques for the assessment of seasonal variations in surface water quality of pasture ecosystems.

    Science.gov (United States)

    Ajorlo, Majid; Abdullah, Ramdzani B; Yusoff, Mohd Kamil; Halim, Ridzwan Abd; Hanif, Ahmad Husni Mohd; Willms, Walter D; Ebrahimian, Mahboubeh

    2013-10-01

    This study investigates the applicability of multivariate statistical techniques including cluster analysis (CA), discriminant analysis (DA), and factor analysis (FA) for the assessment of seasonal variations in the surface water quality of tropical pastures. The study was carried out in the TPU catchment, Kuala Lumpur, Malaysia. The dataset consisted of 1-year monitoring of 14 parameters at six sampling sites. The CA yielded two groups of similarity between the sampling sites, i.e., less polluted (LP) and moderately polluted (MP) at temporal scale. Fecal coliform (FC), NO3, DO, and pH were significantly related to the stream grouping in the dry season, whereas NH3, BOD, Escherichia coli, and FC were significantly related to the stream grouping in the rainy season. The best predictors for distinguishing clusters in temporal scale were FC, NH3, and E. coli, respectively. FC, E. coli, and BOD with strong positive loadings were introduced as the first varifactors in the dry season which indicates the biological source of variability. EC with a strong positive loading and DO with a strong negative loading were introduced as the first varifactors in the rainy season, which represents the physiochemical source of variability. Multivariate statistical techniques were effective analytical techniques for classification and processing of large datasets of water quality and the identification of major sources of water pollution in tropical pastures.

  14. Seasonal Variation of Nutrient Resorption in Nine Canopy Trees of a Wet Tropical Forest

    Science.gov (United States)

    Wood, T. E.; Lawrence, D.

    2006-12-01

    Withdrawal of nutrients at the time of leaf abscission (nutrient resorption) is a nutrient conserving mechanism that could play an important role in stand-level nutrient economy. Currently data on nutrient resorption in wet tropical forests and on how this process varies temporally are sparse. We evaluated the N and P resorption efficiency of nine rain forest canopy tree species in both wet and dry season months. In addition, we measured short-term (bi-weekly) variation in nutrient resorption in the two dominant tree species, Pentaclethra macroloba and Laetia procera, over a 4-month period. We hypothesized that nutrient resorption would be more efficient during the dry season months and that resorption would be low during periods of high rainfall. Contrary to expectations, P resorption efficiency was higher in the wet season for four of the nine canopy tree species, while N resorption did not differ seasonally. The low dry season P resorption efficiency found in this study may be the result of drought stress during short periods of low rainfall, leading to incomplete nutrient resorption from senescing leaves. Nutrient resorption also varied significantly over the short-term. Both P and N resorption efficiency increased in P. macroloba and L. procera as the wet season progressed. The variability in resorption was not related to rainfall or temperature. Instead, the senesced leaf concentrations were a simple proportion of green leaf nutrient concentrations, with short punctuated periods of high resorption efficiency that may be reflective of species-specific phenological events, such as fruit and leaf production. The different timing of the seasonal increase in nutrient resorption between L. procera and P. macroloba supports this hypothesis, deserving of further study.

  15. Seasonal and Diurnal Variations of Atmospheric Non-Methane Hydrocarbons in Guangzhou, China

    Directory of Open Access Journals (Sweden)

    Longfeng Li

    2012-05-01

    Full Text Available In recent decades, high ambient ozone concentrations have become one of the major regional air quality issues in the Pearl River Delta (PRD region. Non-methane hydrocarbons (NMHCs, as key precursors of ozone, were found to be the limiting factor in photochemical ozone formation for large areas in the PRD. For source apportioning of NMHCs as well as ozone pollution control strategies, it is necessary to obtain typical seasonal and diurnal patterns of NMHCs with a large pool of field data. To date, few studies have focused on seasonal and diurnal variations of NMHCs in urban areas of Guangzhou. This study explored the seasonal variations of most hydrocarbons concentrations with autumn maximum and spring minimum in Guangzhou. The diurnal variations of most anthropogenic NMHCs typically showed two-peak pattern with one at 8:00 in the morning and another at 20:00 in the evening, both corresponding to traffic rush hours in Guangzhou, whereas isoprene displayed a different bimodal diurnal curve. Propene, ethene, m, p-xylene and toluene were the four largest contributors to ozone formation in Guangzhou, based on the evaluation of individual NMHCs’ photochemical reactivity. Therefore, an effective strategy for controlling ozone pollution may be achieved by the reduction of vehicle emissions in Guangzhou.

  16. [Metallothioneins in Perna viridis (Bivalvia: Mytilidae): seasonal variation and its relation to reproductive biology].

    Science.gov (United States)

    Lemus, Mairin; Rojas, Nilis; Rojas-Astudillo, Luisa; Chung, Kyung

    2013-06-01

    Metallothionein is a cytosolic protein found in a variety of tissues and have been involved in the regulation of essential trace metals such as copper and zinc, and in the detoxification of essential and nonessential metals. With the aim to study their seasonal variation and their possible role in reproductive behavior, we evaluated metallothioneins (Mts) in Perna viridis, taken from Rio Caribe and Chacopata localities in the North coast of Sucre state, Venezuela. A total of 325 samples were obtained from February to December 2003. We determined the following biometric indices in bivalves: Condition Index (CI), meat yield (RC) and dry weight-length relationship (PSL). Besides, Mts in whole tissue were separated by molecular exclusion chromatography, Sephadex G-50 and quantified by saturation with cadmium. Our results showed that the biometric indices (RC and PSL) had seasonal variations between localities and maturity stages, with the exception of IC. No significant differences were found between sexes. Mts showed seasonal variations between localities, with the highest concentrations between February and March, and minimum ones between September and December, coinciding with the respectively high and low productivity periods in the area. The mussels from Rio Caribe had higher Mts concentration than those from Chacopata. Furthermore, immature mussels showed the highest Mts concentration while the lowest was found in spawned specimens. We found a significant negative relationship between Mts and CI. Our results demonstrated that MTs in Perna viridis are influenced by the condition index and reproductive status, as well as physico-chemical factors in the marine environment.

  17. Hybrid model for forecasting time series with trend, seasonal and salendar variation patterns

    Science.gov (United States)

    Suhartono; Rahayu, S. P.; Prastyo, D. D.; Wijayanti, D. G. P.; Juliyanto

    2017-09-01

    Most of the monthly time series data in economics and business in Indonesia and other Moslem countries not only contain trend and seasonal, but also affected by two types of calendar variation effects, i.e. the effect of the number of working days or trading and holiday effects. The purpose of this research is to develop a hybrid model or a combination of several forecasting models to predict time series that contain trend, seasonal and calendar variation patterns. This hybrid model is a combination of classical models (namely time series regression and ARIMA model) and/or modern methods (artificial intelligence method, i.e. Artificial Neural Networks). A simulation study was used to show that the proposed procedure for building the hybrid model could work well for forecasting time series with trend, seasonal and calendar variation patterns. Furthermore, the proposed hybrid model is applied for forecasting real data, i.e. monthly data about inflow and outflow of currency at Bank Indonesia. The results show that the hybrid model tend to provide more accurate forecasts than individual forecasting models. Moreover, this result is also in line with the third results of the M3 competition, i.e. the hybrid model on average provides a more accurate forecast than the individual model.

  18. Seasonal variation of the {sup 137}Cs level and its relationship with potassium and carbon levels in conifer needles

    Energy Technology Data Exchange (ETDEWEB)

    Rantavaara, Aino, E-mail: aino.rantavaara@stuk.fi [Radiation and Nuclear Safety Authority (STUK), Research and Environmental Surveillance, P.O. Box 14, FI-00881 Helsinki (Finland); Vetikko, Virve, E-mail: virve.vetikko@stuk.fi [Radiation and Nuclear Safety Authority (STUK), Research and Environmental Surveillance, P.O. Box 14, FI-00881 Helsinki (Finland); Raitio, Hannu, E-mail: hannu.raitio@metla.fi [Finnish Forest Research Institute (Metla), P. O. Box 18 , FI-01301 Vantaa (Finland); Aro, Lasse, E-mail: lasse.aro@metla.fi [Finnish Forest Research Institute (Metla), Parkano Unit, Kaironiementie 15, FI-39700 Parkano (Finland)

    2012-12-15

    Seasonal variations in foliar {sup 137}Cs levels were examined in Norway spruce (Picea abies (L.) Karst.), and Scots pine (Pinus sylvestris L.) in western Finland. Our aim was to test the occurrence of seasonal variation in contents and concentrations of {sup 137}Cs, potassium and carbon in needles. The study focused on analysing levels of total {sup 137}Cs in the three youngest needle age classes and comparing them to the levels of potassium and carbon. Spruce and pine needles were collected from 50- and 65-year-old stands on 18 sampling occasions between April 1996 and February 1997. Phases of intensive growth, needle elongation and dormancy were apparent in the time series for the needle contents and activity concentration of {sup 137}Cs, both of which varied according to needle age class and tree species. The sequence of phases with a temporal fluctuation of needle contents, activity concentrations of {sup 137}Cs and concentrations of K and carbon varied occasionally, and the efficiency of their translocation revealed some differences in the dynamics of {sup 137}Cs, K and carbon in spruce and pine. The data clearly showed that the needles' K contents responded strongly to changes in K demand from other parts of the tree due to seasonal changes and that these responses were stronger than the associated retranslocations of {sup 137}Cs, particularly in Scots pine. During intensive growth, K was less mobile than {sup 137}Cs in the needles. The uptake of {sup 137}Cs by current-year needles is simultaneously affected by uptake from the soil via the roots and retranslocation from other internal sources, and both of these processes affect the observed transfer rates during the growth period. Our results provided information on the transfer rates and revealed differentiation of root uptake and retranslocation of {sup 137}Cs in needles. The study can support dynamic modelling of atmospheric {sup 137}Cs contamination in forests. -- Highlights: Black

  19. Nitrogen Dynamics Variation in Overlying Water of Jinshan Lake, China

    Directory of Open Access Journals (Sweden)

    Xiaohong Zhou

    2015-01-01

    Full Text Available Jinshan Lake is a famous urban landscape lake with approximately 8.8 km2 water area, which is located on the north of Zhenjiang, of Jiangsu Province, China. Eighteen sampled sites were selected and overlying water was sampled from 2013 to 2014 to study the seasonal and spatial variation of nitrogen in overlying water of Jinshan Lake. Results showed that physicochemical characteristics of temperature, pH, and DO showed high seasonal variation, whereas they had no significant spatial differences in the 18 sampling points (P>0.05 in overlying water of Jinshan Lake. Nitrogen concentrations showed strong seasonal variation trends. The ranked order of TN was as follows: spring > summer > autumn > winter; the order of NH4+-N was as follows: spring > autumn > summer > winter, whereas NO3--N concentrations revealed an inverse seasonal pattern, with maxima occurring in winter and minimal values occurring in spring. Nitrogen concentrations had dramatic spatial changes in 18 sampling points of Jinshan Lake. Physicochemical parameter difference, domestic wastes pollution, and rainfall runoff source may have led to seasonal and spatial fluctuation variations of nitrogen in overlying water of Jinshan Lake, China.

  20. Seasonal Variations in Sugar Contents and Microbial Community Behavior in a Ryegrass Soil

    Science.gov (United States)

    Medeiros, P. M.; Fernandes, M. F.; Dick, R. P.; Simoneit, B. R.

    2004-12-01

    Soil is a complex mixture of numerous inorganic and organic constituents that vary in size, shape, chemical constitution and reactivity, and hosts numerous organisms. Total sugars have been estimated to constitute 10% (average) of soil organic matter, occurring in living and decaying organisms, as well as in extracellular materials. The role of sugars in soils is attributed to their influence on soil structure, chemical processes, plant nutrition and microbial activity. The sources of sugars in soils are: a) plants (the primary source); b) animals (the minor source), and c) microorganisms (fungi, bacteria, algae), which decompose the primary plant and animal material, and synthesize the major part of soil carbohydrates. A particular soil sample provides a momentary glimpse into a dynamic system (continuous addition, degradation and synthesis) that might, except for seasonal variations, be in equilibrium. The purpose of this study is to identify and quantify the major sugars in a grass soil and characterize the relationship between their concentration variations and soil microbial behavior over an annual cycle. Soil samples were collected monthly in a ryegrass field close to Corvallis, Oregon, and analyzed by gas chromatography-mass spectrometry as total silylated extracts for sugar composition, and by gas chromatography-flame ionization as fatty acid methyl esters derived from phospholipids and neutral lipids (PLFA and NLFA, respectively). The preliminary results of the first six-month experiment (from January to June, 2004) show that as the ambient temperatures increase the sugar concentrations (glucose, fructose, sucrose and trehalose) also tend to increase in the soil. A decrease is observed in March when precipitation was low during the whole month. The same trend is observed for the active biomass of fungi and bacteria estimated by their fatty acids derived from phospholipids. Fatty acids 18:2ω 6c and 18:3ω 6c are used as fungal biomarkers. Branched (15:0i

  1. Seasonal variation in carbon dioxide exchange over a Mediterranean annual grassland in California

    Energy Technology Data Exchange (ETDEWEB)

    Xu, L; Baldocchi, D

    2004-05-01

    Understanding how environmental variables affect the processes that regulate the carbon flux over grassland is critical for large-scale modeling research, since grasslands comprise almost one-third of the earth's natural vegetation. To address this issue, fluxes of CO{sub 2} (F{sub c}, flux toward the surface is negative) were measured over a Mediterranean, annual grassland in California, USA for 2 years with the eddy covariance method. To interpret the biotic and abiotic factors that modulate F{sub c} over the course of a year we decomposed net ecosystem CO{sub 2} exchange into its constituent components, ecosystem respiration (R{sub eco}) and gross primary production (GPP). Daytime R{sub eco} was extrapolated from the relationship between temperature and nighttime F{sub c} under high turbulent conditions. Then, GPP was estimated by subtracting daytime values of F{sub c} from daytime estimates of R{sub eco}. Results show that most of carbon exchange, both photosynthesis and respiration, was limited to the wet season (typically from October to mid-May). Seasonal variations in GPP followed closely to changes in leaf area index, which in turn was governed by soil moisture, available sunlight and the timing of the last frost. In general, R{sub eco} was an exponential function of soil temperature, but with season-dependent values of Q{sub 10}. The temperature-dependent respiration model failed immediately after rain events, when large pulses of R{sub eco} were observed. Respiration pulses were especially notable during the dry season when the grass was dead and were the consequence of quickly stimulated microbial activity. Integrated values of GPP, R{sub eco}, and net ecosystem exchange (NEE) were 867, 735, and -132g C m{sup -2}, respectively, for the 2000-2001 season, and 729, 758, and 29g C m{sup -2} for the 2001-2002 season. Thus, the grassland was a moderate carbon sink during the first season and a weak carbon source during the second season. In contrast to a

  2. SU-E-T-136: Assessment of Seasonal Linear Accelerator Output Variations and Associated Impacts

    Energy Technology Data Exchange (ETDEWEB)

    Bartolac, S; Letourneau, D [Princess Margaret Cancer Centre, Toronto, Ontario (Canada); University of Toronto, Toronto, Ontario (Canada)

    2015-06-15

    Purpose: Application of process control theory in quality assurance programs promises to allow earlier identification of problems and potentially better quality in delivery than traditional paradigms based primarily on tolerances and action levels. The purpose of this project was to characterize underlying seasonal variations in linear accelerator output that can be used to improve performance or trigger preemptive maintenance. Methods: Review of runtime plots of daily (6 MV) output data acquired using in house ion chamber based devices over three years and for fifteen linear accelerators of varying make and model were evaluated. Shifts in output due to known interventions with the machines were subtracted from the data to model an uncorrected scenario for each linear accelerator. Observable linear trends were also removed from the data prior to evaluation of periodic variations. Results: Runtime plots of output revealed sinusoidal, seasonal variations that were consistent across all units, irrespective of manufacturer, model or age of machine. The average amplitude of the variation was on the order of 1%. Peak and minimum variations were found to correspond to early April and September, respectively. Approximately 48% of output adjustments made over the period examined were potentially avoidable if baseline levels had corresponded to the mean output, rather than to points near a peak or valley. Linear trends were observed for three of the fifteen units, with annual increases in output ranging from 2–3%. Conclusion: Characterization of cyclical seasonal trends allows for better separation of potentially innate accelerator behaviour from other behaviours (e.g. linear trends) that may be better described as true out of control states (i.e. non-stochastic deviations from otherwise expected behavior) and could indicate service requirements. Results also pointed to an optimal setpoint for accelerators such that output of machines is maintained within set tolerances

  3. Seasonal Variation in Fluoride Content in Groundwaters of Langtang Area, Northcentral Nigeria

    Science.gov (United States)

    Dibal, H. U.; Dajilak, W. N.; Lekmang, I. C.; Nimze, L. W.; Yenne, E. Y.

    2017-06-01

    Thirty groundwater samples were collected at the peak of the rainy season and analysed for fluoride and other cations and anions in drinking water sources of Langtang area. For comparative purposes, thirty seven groundwater samples were collected in the dry season. The aim of the study was to determine variation in fluoride content with respect to the seasons. Fluoride in water was determined by the Ion Selective Electrode (ISE) and the cations by the Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The anion (sulphate) was determined by Multi - Ion Colorimeter, bicarbonate and chloride by titration method. In addition fluorine content in aquifer materials from a borehole section were determined by Fusion method. The two seasons show variation in content of fluoride in groundwater. Fluoride content in groundwater is higher in the dry season ranging from 0.13 - 10.3 mg/l compared to the 0.06 - 4.60 mg/l values in the rainy season. Content of fluorine (0.01 wt %) in the aquifer materials (sands) is low from depth of 0 to 7.95 m. However, fluorine content increases with depth, from 7.95 to 10.60 m with concentration of 0.04 wt %, 0.05 wt % from 10.60 to 13.25m, and 0.07 wt % from 13.25 to 15.70 m, the content of fluorine however, decreased at depth 15.70 to18.55m with concentration of 0.02 wt % even with fluorite mineral in the aquifer material at this depth. Dilution of fluoride ion as a result of rain input which recharges the aquifer may be the main reason for lower values recorded in the rainy season. Over fifty and sixty percent of waters in both dry and rainy season have fluoride concentration above the WHO upper limit of 1.5 mg/l. Consumption of these elevated values of fluoride in groundwater of the study area, clearly manifests as symptoms of dental fluorosis.

  4. Effect of Management Practices on Seasonal Dynamics of Organic Carbon in Soils Under Bamboo Plantations

    Institute of Scientific and Technical Information of China (English)

    ZHOU Guo-Mo; XU Jian-Ming; JIANG Pei-Kun

    2006-01-01

    Soil samples for conventional management (CM) and intensive management (IM) practices were taken over a year at2-month intervals to determine the effect of management practices on soil organic carbon (SOC) and to quantify seasonal dynamics in SOC for bamboo (Phyllostachys pubescens Mazel ex H. de Lehaie) stands. The results with IM compared to CM showed large decreases in total organic carbon (TOC), microbial biomass carbon (MBC), water-soluble organic carbon (WSOC), and the MBC/TOC ratio in the soils. With all IM plots in the 0-20 cm depth across sampling periods,average decreases compared with CM were: TOC, 12.1%; MBC, 26.1%; WSOC, 29.3%; the MBC/TOC ratio, 16.1%;and the WSOC/TOC ratio, 20.0%. Due to seasonal changes of climate, seasonal variations were observed in MBC and WSOC. Soil MBC in the 0-20 cm depth in September compared to May were 122.9% greater for CM and 57.6% greater for IM. However, due primarily to soil temperature, soil MBC was higher during the July to November period, whereas because of soil moisture, WSOC was lower in July and January. This study revealed that intensive management in bamboo plantations depleted the soil C pool; therefore, soil quality with IM should be improved through application of organic manures.

  5. Culex mosquitoes in temporary urban rain pools: seasonal dynamics and relation to environmental variables.

    Science.gov (United States)

    Fischer, Sylvia; Schweigmann, Nicolás

    2004-12-01

    The study was conducted in a park of Buenos Aires City, where a total of 89 rain pools were sampled weekly for mosquito immature stages over a one-year period. The aim of the present paper was to investigate the seasonal dynamics of three Culex species breeding in temporary rain pools and to analyze the relationships of the presence of these species to pool dimensions, pool age, vegetation, and insolation degree. The three species showed differences in their seasonal patterns, Culex dolosus being present during the whole year, Culex pipiens mainly in the summer season, and Culex maxi almost exclusively during the fall. The variable explaining most of the variation among sampling dates in species composition was weekly mean temperature. A significant positive association was detected among mosquito species, as they were recorded together more frequently than expected by chance. The statistical analyses performed revealed significant positive relationships of all three mosquito species to increasing surface area, whereas no relationship to insolation degree was detected in the studied pools. Culex pipiens and Culex dolosus showed positive relationships to increasing vegetation cover, whereas the presence of Culex dolosus was also related to pool age.

  6. Carbon dioxide seasonality in dynamically ventilated caves: the role of advective fluxes

    Science.gov (United States)

    Lang, Marek; Faimon, Jiří; Godissart, Jean; Ek, Camille

    2017-08-01

    The seasonality in cave CO2 levels was studied based on (1) a new data set from the dynamically ventilated Comblain-au-Pont Cave (Dinant Karst Basin, Belgium), (2) archive data from Moravian Karst caves, and (3) published data from caves worldwide. A simplified dynamic model was proposed for testing the effect of all conceivable CO2 fluxes on cave CO2 levels. Considering generally accepted fluxes, i.e., the direct diffusive flux from soils/epikarst, the indirect flux derived from dripwater degassing, and the input/output fluxes linked to cave ventilation, gives the cave CO2 level maxima of 1.9 × 10-2 mol m-3 (i.e., ˜ 440 ppmv), which only slightly exceed external values. This indicates that an additional input CO2 flux is necessary for reaching usual cave CO2 level maxima. The modeling indicates that the additional flux could be a convective advective CO2 flux from soil/epikarst driven by airflow (cave ventilation) and enhanced soil/epikarstic CO2 concentrations. Such flux reaching up to 170 mol s-1 is capable of providing the cave CO2 level maxima up to 3 × 10-2 mol m-3 (70,000 ppmv). This value corresponds to the maxima known from caves worldwide. Based on cave geometry, three types of dynamic caves were distinguished: (1) the caves with the advective CO2 flux from soil/epikarst at downward airflow ventilation mode, (2) the caves with the advective soil/epikarstic flux at upward airflow ventilation mode, and (3) the caves without any soil/epikarstic advective flux. In addition to CO2 seasonality, the model explains both the short-term and seasonal variations in δ13C in cave air CO2.

  7. Seasonal changes in markers of oxidative damage to lipids and DNA; correlations with seasonal variation in diet.

    Science.gov (United States)

    Smolková, Bozena; Dusinská, Mária; Raslová, Katarína; McNeill, Geraldine; Spustová, Viera; Blazícek, Pavol; Horská, Alexandra; Collins, Andrew

    2004-07-13

    We have addressed the question whether the relatively high incidence of cardiovascular disease and certain cancers in countries of central/eastern Europe might be associated with nutritional imbalance, in particular a lack of fresh fruit and vegetables in the diet in winter months. Nutritional parameters and markers of oxidative stress were studied in three Slovak population groups: 46 survivors of myocardial infarction (MI group) and 48 healthy, normolipidemic subjects (NL), living in or near Bratislava; and 70 rural controls (RC group) living a more traditional life style in a country town. Data were collected in February/March and September/October of two consecutive years, representing times of minimum and maximum local availability of fresh fruits and vegetables. Oxidative stress was monitored using two biomarkers; plasma malondialdehyde (MDA, a product of lipid peroxidation), and oxidation of lymphocyte DNA. Dietary antioxidants, folic acid, homocysteine, total antioxidant status (FRAP) and uric acid were measured in plasma. Food frequency questionnaires were administered. Vegetable consumption in summer/autumn was twice as high as in winter/spring. DNA damage did not vary consistently across the seasons. Mean plasma MDA levels for the MI and NL groups showed a clear pattern, with high levels in winter/spring and low levels in summer/autumn. Folic acid showed a reciprocal pattern, similar to the pattern of vegetable consumption. The RC group had the smallest seasonal variations in vegetable consumption, folic acid levels, and MDA. High winter MDA levels are seen in those individuals with relatively low folic acid; they never occur in subjects with high plasma folic acid, implying that folic acid might directly protect against lipid oxidation. This study illustrates the value of the molecular epidemiological approach, while emphasising the need for well characterised population groups and valid biomarkers.

  8. Sediment Transport Dynamics in River Networks: A Model for Higher-Water Seasons

    Science.gov (United States)

    Huo, Jie; Wang, Xu-Ming; Hao, Rui; Zhang, Jin-Feng

    A dynamical model is proposed to study sediment transport in river networks in higher-water seasons. The model emphasizes the difference between the sediment-carrying capability of the stream in higher-water seasons and that in lower-water seasons. The dynamics of sediment transport shows some complexities such as the complex dependence of the sediment-carrying capability on sediment concentration, the response of the channel(via erosion or sedimentation) to the changes of discharge.

  9. Seasonal variation in pectoralis muscle and heart myostatin and tolloid-like proteinases in small birds: a regulatory role for seasonal phenotypic flexibility?

    Science.gov (United States)

    Swanson, David L; King, Marisa O; Harmon, Erin

    2014-02-01

    Seasonally variable environments produce seasonal phenotypes in small birds such that winter birds have higher thermogenic capacities and pectoralis and heart masses. One potential regulator of these seasonal phenotypes is myostatin, a muscle growth inhibitor, which may be downregulated under conditions promoting increased energy demand. We examined summer-to-winter variation in skeletal muscle and heart masses and used qPCR and Western blots to measure levels of myostatin and its metalloproteinase activators TLL-1 and TLL-2 for two small temperate-zone resident birds, American goldfinches (Spinus tristis) and black-capped chickadees (Poecile atricapillus). Winter pectoralis and heart masses were significantly greater than in summer for American goldfinches. Neither myostatin expression nor protein levels differed significantly between seasons for goldfinch pectoralis. However, myostatin levels in goldfinch heart were significantly greater in summer than in winter, although heart myostatin expression was seasonally stable. In addition, expression of both metalloproteinase activators was greater in summer than in winter goldfinches for both pectoralis and heart, significantly so except for heart TLL-2 (P = 0.083). Black-capped chickadees showed no significant seasonal variation in muscle or heart masses. Seasonal patterns of pectoralis and heart expression and/or protein levels for myostatin and its metalloproteinase activators in chickadees showed no consistent seasonal trends, which may help explain the absence of significant seasonal variation in muscle or heart masses for chickadees in this study. These data are partially consistent with a regulatory role for myostatin, and especially myostatin processing capacity, in mediating seasonal metabolic phenotypes of small birds.

  10. Predicting seasonal variations in coastal seabird habitats in the English Channel and the Bay of Biscay

    Science.gov (United States)

    Virgili, A.; Lambert, C.; Pettex, E.; Dorémus, G.; Van Canneyt, O.; Ridoux, V.

    2017-07-01

    Seabirds, like all animals, have to live in suitable habitats to fulfil their energetic needs for both somatic and reproductive growth and maintenance. Apart from migration trips, all coastal seabirds are linked to the coast, because they need to return daily to land for resting or breeding. Their use of marine habitats strongly depends on their biology, but also on environmental conditions, and can be described using habitat models. This study aimed to: (1) identify the processes that mostly influence seabird distributions along the coasts of the English Channel and the Bay of Biscay; (2) determine seasonal variations of these processes, (3) provide prediction maps that describe the species distributions. We collected data of coastal seabird sightings from aerial surveys carried out in the English Channel and the eastern North Atlantic in the winter 2011-2012 and summer 2012. We classified seabirds into morphological groups and described their habitats using physiographic and oceanographic variables in Generalised Additive Models (GAMs). Finally, we produced maps of predicted distributions by season for each group. The distributions of coastal seabirds were essentially determined by the distance to the nearest coast, with a weaker influence of oceanographic variables. The nature of the substrate, sand or rock, combined with the timing of reproduction, also contributed to determine seasonal at-sea distributions for some species. The highest densities were predicted near the coast, particularly in bays and estuaries for strictly coastal species with possible variations depending on the season. From this study, we were able to predict the seasonal distribution of the studied species according to varying environmental parameters that changed over time, allowing us to understand better their behaviour and ecology.

  11. Vertical gradients and seasonal variation in stem CO2 efflux within a Norway spruce stand.

    Science.gov (United States)

    Tarvainen, Lasse; Räntfors, Mats; Wallin, Göran

    2014-05-01

    Stem CO2 efflux is known to vary seasonally and vertically along tree stems. However, annual tree- and stand-scale efflux estimates are commonly based on measurements made only a few times a year, during daytime and at breast height. In this study, the effect of these simplifying assumptions on annual efflux estimates and their influence on the estimates of the importance of stems in stand-scale carbon cycling are evaluated. In order to assess the strength of seasonal, diurnal and along-stem variability in CO2 efflux, half-hourly measurements were carried out at three heights on three mature Norway spruce (Picea abies (L.) Karst.) trees over a period of 3 years. Making the common assumption of breast height efflux rates being representative of the entire stem was found to result in underestimations of 10-17% in the annual tree-scale CO2 efflux. Upscaling using only daytime measurements from breast height increased the underestimation to 15-20%. Furthermore, the results show that the strength of the vertical gradient varies seasonally, being strongest in the early summer and non-existent during the cool months. The observed seasonality in the vertical CO2 efflux gradient could not be explained by variation in stem temperature, temperature response of the CO2 efflux (Q10), outer-bark permeability, CO2 transport in the xylem or CO2 release from the phloem. However, the estimated CO2 concentration immediately beneath the bark was considerably higher in the upper stem during the main period of diameter growth, coinciding with the strongest vertical efflux gradient. These results suggest that higher growth rates in the upper stem are the main cause for the observed vertical variation in the stem CO2 effluxes. Furthermore, the results indicate that accounting for the vertical efflux variation is essential for assessments of the importance of stems in stand-scale carbon cycling.

  12. A regional study of the seasonal variation in the molecular composition of rainwater

    Science.gov (United States)

    Cottrell, Barbara A.; Gonsior, Michael; Isabelle, Lorne M.; Luo, W.; Perraud, Véronique; McIntire, Theresa M.; Pankow, James F.; Schmitt-Kopplin, Philippe; Cooper, William J.; Simpson, André J.

    2013-10-01

    Rainwater is not only a critical source of drinking and agricultural water but it plays a key role in the fate and transport of contaminants through their removal by wet deposition. Rainwater is a complex mixture of organic compounds yet despite its importance its spatial and temporal variability are not well understood and less than 50% of the organic matter has been characterized. In-depth analytical approaches were used in this study to characterize the seasonal variation in rainwater composition. Rainwater samples were collected over a one-year period in Scarborough, Ontario, Canada. The seasonal variation of atmospheric organic carbon (AOC) in rainwater was analyzed by excitation-emission matrix spectroscopy (EEMs), 1D and 2D NMR with compound identification by spectral database matching, GC-MS, FT-ICR-MS, and GC × GC-TOFMS. This combination of techniques provided four complementary datasets, with less than 10% overlap, of anthropogenic and biogenic AOC. NMR with database matching identified over 100 compounds, primarily carboxylic acids, carbohydrates, and nitrogen-containing compounds. GC × GC-TOFMS analysis identified 344 compounds in two rain events with 33% of the compounds common to both events. FT-ICR-MS generated a seasonally dependent profile of 1226-1575 molecular ions of CHO, CHOS, and CHON elemental composition. FT-ICR-MS and GC × GC-TOFMS datasets were compared using van Krevelen diagrams (H/C vs. O/C), the H/C ratio vs. mass/charge (m/z), and the carbon oxidation state/carbon number matrix. Fluorescence patterns were correlated with NMR results resulting in the identification one seasonally-dependent component of chromophoric dissolved organic matter (CDOM). This study demonstrated the importance of using of an integrated analytical approach to monitor the compositional variation of AOC.

  13. Seasonal and spatial variations of snow chemistry on Mount Logan, Yukon, Canada

    Science.gov (United States)

    Goto-Azuma, Kumiko; Koerner, Roy M.; Demuth, Michael N.; Watanabe, Okitsugu

    Three ice cores were recovered on or near Mount Logan, Yukon, Canada, at 3017, 4135 and 5340 m a.s.l. in 2002. Prior to ice-core drilling, we collected snow-pit and shallow core samples from Mount Logan in 2001 to study seasonal and spatial variations of snow chemistry. We dug snow pits at six sites between 2420 and 5340 m a.s.l. before the beginning of the melt season, with the exception of a pit at 3180 m a.s.l., where the melt season had just started but had affected only the near-surface stratigraphy. Three of the pits were extended deeper with a shallow core. The snow-pit and core samples were analyzed for ion chemistry and δ18O. A series of depth profiles of ions and δ18O shows spatial variations, though characteristic peaks can usually be traced across all the profiles. Concentrations and deposition fluxes of Na+ and Cl-, which are mainly of sea-salt origin, decrease with altitude. On the other hand, deposition fluxes of NO3-, SO42-, Ca2+ and NH4+ show a weak positive relationship with elevation below the summit plateau. Stable isotopes (δ18O) decrease with altitude, with a distinctive jump between 3200 and 4500 m a.s.l., as was reported previously. Stable isotopes (δ18O), Cl-, CH3SO3-(MSA), Na+ and Ca2+ show clear seasonal variations, which would enable us to date the cores by annual-layer counting.

  14. The sensitivity of wood production to seasonal and interannual variations in climate in a lowland Amazonian rainforest.

    Science.gov (United States)

    Rowland, Lucy; Malhi, Y; Silva-Espejo, J E; Farfán-Amézquita, F; Halladay, K; Doughty, C E; Meir, P; Phillips, O L

    2014-01-01

    Understanding climatic controls on tropical forest productivity is key to developing more reliable models for predicting how tropical biomes may respond to climate change. Currently there is no consensus on which factors control seasonal changes in tropical forest tree growth. This study reports the first comprehensive plot-level description of the seasonality of growth in a Peruvian tropical forest. We test whether seasonal and interannual variations in climate are correlated with changes in biomass increment, and whether such relationships differ among trees with different functional traits. We found that biomass increments, measured every 3 months on the two plots, were reduced by between 40 and 55% in the peak dry season (July-September) relative to peak wet season (January-March). The seasonal patterns of biomass accumulation are significantly (p productive in the wet season, but more vulnerable to water limitation in the dry season.

  15. Impact of ENSO on seasonal variations of Kelvin Waves and mixed Rossby-Gravity Waves

    Science.gov (United States)

    Rakhman, Saeful; Lubis, Sandro W.; Setiawan, Sonni

    2017-01-01

    Characteristics of atmospheric equatorial Kelvin waves and mixed Rossby-Gravity (MRG) waves as well as their relationship with tropical convective activity associated with El Niño-Southern Oscillation (ENSO) were analyzed. Kelvin waves and MRG waves were identified by using a Space-Time Spectral Analysis (STSA) technique, where the differences in the strength of both waves were quantified by taking the wave spectrum differences for each ENSO phase. Our result showed that Kelvin wave activity is stronger during an El Nino years, whereas the MRG wave activity is stronger during the La Nina years. Seasonal variations of Kelvin wave activity occurs predominantly in MAM over the central to the east Pacific in the El Nino years, while the strongest seasonal variation of MRG wave activity occus in MAM and SON over the northern and southern Pacific during La Nina years. The local variation of Kelvin wave and MRG wave activities are found to be controlled by variation in lower level atmospheric convection induced by sea surface temperature in the tropical Pacific Ocean.

  16. Seasonal variation of chloro-s-triazines in the Hartbeespoort Dam catchment, South Africa.

    Science.gov (United States)

    Rimayi, Cornelius; Odusanya, David; Weiss, Jana M; de Boer, Jacob; Chimuka, Luke

    2017-09-14

    Seasonal variation of eight chloro-s-triazine herbicides and seven major atrazine and terbuthylazine degradation products was monitored in the Hartbeespoort Dam catchment using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS/MS). Lake, river and groundwater were sampled from the Hartbeespoort Dam catchment over four seasons and the downstream Jukskei River was monitored during the winter season. Triazine herbicide concentrations in the Hartbeespoort Dam were in the order atrazine>simazine>propazine>ametryn>prometryn throughout the four seasons sampled. Triazine herbicide concentrations in the Hartbeespoort Dam surface water were highest in summer and gradually decreased in successive seasons of autumn, winter and spring. Terbuthylazine was the only triazine herbicide detected at all sampling sites in the Jukskei River, though atrazine recorded much higher concentrations for the N14 and Kyalami sites, with concentrations of 923 and 210ngL(-1) respectively, compared to 134 and 74ngL(-1) for terbuthylazine. Analytical results in conjunction with river flow data indicate that the Jukskei and Crocodile Rivers contribute the greatest triazine herbicide loads into the Hartbeespoort Dam. No triazine herbicides were detected in the fish muscle tested, showing that bioaccumulation of triazine herbicides is negligible. Atrazine and terbuthylazine metabolites were detected in the fish muscle with deethylatrazine (DEA) being detected in both catfish and carp muscle at low concentrations of 0.2 and 0.3ngg(-1), respectively. Desethylterbuthylazine (DET) was detected only in catfish at a concentration of 0.3ngg(-1). With atrazine herbicide groundwater concentrations being >130ngL(-1) for all seasons and groundwater ∑triazine herbicide concentrations ranging between 527 and 367ngL(-1), triazine compounds in the Hartbeespoort Dam catchment may pose a risk to humans and wildlife in light findings of endocrine and immune disrupting

  17. Variable variation: annual and seasonal changes in offspring sex ratio in a bat.

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    Robert M R Barclay

    Full Text Available Many organisms produce offspring with sex-ratios that deviate from equal numbers of males and females, and numerous adaptive explanations have been proposed. In some species, offspring sex-ratio varies across the reproductive season, again with several explanations as to why this might be adaptive. However, patterns for birds and mammals are inconsistent, and multiple factors are likely involved. Long-term studies on a variety of species may help untangle the complexity. I analyzed a long-term data set on the variation in offspring sex-ratio of the big brown bat, Eptesicus fuscus, a temperate-zone, insectivorous species. Sex ratio varied seasonally, but only in some years. Births early in the season were significantly female biased in years in which parturition occurred relatively early, but not in years with late parturition. Survival of female pups increased with earlier median birth date for the colony, and early-born females were more likely to survive and reproduce as one-year olds, compared to later-born pups. I argue that, due to the unusual timing of reproductive activities in male and female bats that hibernate, producing female offspring early in the year increases their probability of reproducing as one year olds, but this is not the case for male offspring. Thus, mothers that can give birth early in the year, benefit most by producing a female pup. The relative benefit of producing female or male offspring varies depending on the length of the growing season and thus the time available for female pups to reach sexual maturity. This suggests that not only does sex-ratio vary seasonally and among years, depending on the condition of the mother and the environment, but also likely varies geographically due to differences in season length.

  18. Eclampsia and seasonal variation in the tropics - a study in Nigeria

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    Efenae Russ Efetie

    2009-05-01

    Full Text Available Background:A retrospective observational study on the seasonal variation in the admission of eclampsia patients to the multi-disciplinary intensive care unit (ICU of National Hospital, Abuja, Nigeria over a five-year span (March 2000 – March 2005 was carried out. Methods:The patient’s case files and ICU records were used to extract the needed data. The diagnosis of eclampsia was based on clinical and laboratory findings by the obstetricians. Results:There were a total of 5,987 deliveries during the study period. Forty-six eclamptics were admitted to the ICU during the study period giving an ICU admission rate of 7.6/1000 deliveries. The average age of the patients was 28.6 years. Six patients (13% were booked for antenatal care in the hospital, while forty patients (87% were referred. Average duration of stay in the ICU was 4.6 days (range 1-42 days. Thirty-one eclamptics (67.4% were admitted to the ICU during the rainy season (April to October and fifteen (32.6% during the dry season (November to April. The rainy season is associated with a lower average high temperature and a higher humidity than the dry season. There is a view that holds that increasing humidity and a lower temperature is associated with increased incidence of eclampsia. There were thirteen deaths giving a case fatality rate of 28.2%. The causes of death were HELLP (haemolysis, elevated liver enzymes, low platelet count syndrome in six patients, disseminated intravascular coagulation in two patients, and acute renal failure (ARF in two patients. Septicemia, lobar pneumonia/heart failure and cerebrovascular accident accounted for one death each. Conclusion:In this study, we found an association between the rainy season and the incidence of eclampsia to our intensive care unit. This association should be further explored.

  19. Seasonal variation of the O3-CO correlation derived from remote sensing measurements over western Japan

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    Ohyama, Hirofumi; Kawakami, Shuji; Uchino, Osamu; Sakai, Tetsu; Morino, Isamu; Nagai, Tomohiro; Shiomi, Kei; Sakashita, Masanori; Akaho, Taiga; Okumura, Hiroshi; Arai, Kohei

    2016-12-01

    We used a lower tropospheric ozone column (LTOC) and column-averaged dry-air mole fraction of carbon monoxide (XCO) data observed in the area around Saga, which is located in western Japan and is close to the Asian continent, with an aim to investigate whether these data can characterize the seasonal variation of the photochemical ozone (O3) formation in the northeast Asian Pacific rim region. The LTOC data after April 2009 were retrieved from thermal infrared spectra measured by the Thermal and Near Infrared Sensor for Carbon Observation-Fourier Transform Spectrometer (TANSO-FTS) onboard the Greenhouse Gases Observing Satellite (GOSAT). The XCO data after July 2011 were obtained from ground-based high-resolution FTS measurements at Saga. The retrieved LTOCs were validated with those derived from a differential absorption lidar for O3 at Saga. The LTOCs showed a distinct seasonal variation that reached a maximum in late spring (May or June) and a local minimum in winter. In addition to the general seasonal pattern, we observed pronounced minimums in July or August. The XCO concentrations showed a maximum in spring and a minimum in summer. These seasonal patterns are consistent with those observed from mountainous sites in Japan. The origins of the air masses reaching Saga were characterized for each season according to backward trajectories, and the factors causing the temporal variations of the LTOCs and the XCO were identified based on the transport paths of the air masses. The enhancement of the LTOC relative to the XCO (ΔO3/ΔCO ratio) reveals significant positive correlations in the spring and summer seasons with slopes of 0.21 and 0.45 ppb/ppb, respectively. The effects of stratospheric air intrusion on the observed ΔO3/ΔCO ratio in spring were investigated using meteorological data (backward trajectory and potential vorticity) and column-averaged hydrogen fluoride data derived from the ground-based FTS measurements. It was found that there was little

  20. Short-term community dynamics in seasonal and hyperseasonal cerrados

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    MV. Cianciaruso

    Full Text Available In South America, the largest seasonal savanna region is the Brazilian cerrado. Our aim was to study temporal changes in some community descriptors, such as floristic composition, richness, species density, plant density, and cylindrical volume, in a seasonal cerrado, comparing it to a nearby hyperseasonal cerrado. In four different seasons, we placed randomly ten 1 m² quadrats in each vegetation form and sampled all the vascular plants. Seasonal changes in floristic composition, species density, and plant density were less pronounced in the seasonal than in the hyperseasonal cerrado. Floristic similarity between the vegetation forms was lower when the hyperseasonal cerrado was waterlogged. Richness and species density were higher in the seasonal cerrado, which reached its biomass peak at mid rainy season. The hyperseasonal cerrado, in turn, reached its biomass peak at early rainy season and, despite the waterlogging, maintained it until late rainy season. In the hyperseasonal cerrado, waterlogging acts as an environmental filter restricting the number of cerrado species able to withstand it. The seasonal cerrado community was more stable than the hyperseasonal one. Our results corroborated the idea that changes in the environmental filters will affect floristic composition and community structure in savannas.

  1. Seasonal changes in Titan's middle-atmosphere chemistry and dynamics

    Science.gov (United States)

    Teanby, N. A.; Irwin, P. G. J.; Nixon, C. A.; de Kok, R.; Vinatier, S.; Coustenis, A.; Sefton-Nash, E.; Calcutt, S. B.; Flasar, F. M.

    2013-09-01

    Titan is the largest satellite of Saturn and is the only moon in our solar system with a significant atmo- sphere. Titan's middle-atmosphere (stratosphere and mesosphere) circulation usually comprises a single hemisphere to hemisphere meridional circulation cell, with upwelling air in the summer hemisphere and sub- siding air at the winter pole with an associated winter polar vortex. Titan has an axial tilt (obliquity) of 26.7°, so during its 29.5 Earth year annual cycle pronounced seasonal effects are encountered as the relative solar insolation in each hemisphere changes. The most dramatic of these changes is the reversal in global meridional circulation as the peak solar heating switches hemispheres after an equinox. Titan's northern spring equinox occurred in August 2009, and since then many middle-atmosphere changes have been observed by Cassini that were previously impossible to study (1,2,3,4). Here we present a detailed analysis of the post equinox changes in middle-atmosphere temperature and composition measured with Cassini's Composite InfraRed Spectrometer (CIRS), use these to infer changes in atmospheric circulation, and explore implications for atmospheric photochemical and dynamical processes. Our results show that the meridional circulation has now reversed (1).

  2. Effect of seasonal variation on adult clinical laboratory parameters in Rwanda, Zambia, and Uganda: implications for HIV biomedical prevention trials.

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    Eugene Ruzagira

    Full Text Available To investigate the effect of seasonal variation on adult clinical laboratory parameters in Rwanda, Zambia, and Uganda and determine its implications for HIV prevention and other clinical trials.Volunteers in a cross-sectional study to establish laboratory reference intervals were asked to return for a seasonal visit after the local season had changed from dry to rainy or vice versa. Volunteers had to be clinically healthy, not pregnant and negative for HIV, Hepatitis B and C, and syphilis infection at both visits. At each visit, blood was taken for measurement of hemoglobin, haematocrit, mean corpuscular volume, red blood cells, platelets, total white blood cells (WBC, neutrophils, lymphocytes, monocytes, eosinophils, basophils, CD4/CD8 T cells, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, direct bilirubin, total bilirubin, total immunoglobulin gamma, total protein, creatinine, total amylase, creatine phosphokinase and lactate dehydrogenase (LDH. Consensus dry season reference intervals were applied to rainy season values (and vice versa and the proportion of 'out-of-range' values determined. Percentage differences between dry and rainy season parameter mean values were estimated.In this cohort of 903 volunteers, less than 10.0% of consensus parameter (except LDH values in one season were "out-of-range" in the other. Twenty-two (22 percent of rainy season LDH values fell outside of the consensus dry season interval with the higher values observed in the rainy season. Variability between consensus seasonal means ranged from 0.0% (total WBC, neutrophils, monocytes, basophils, and direct bilirubin to 40.0% (eosinophils. Within sites, the largest seasonal variations were observed for monocytes (Masaka, 11.5%, LDH (Lusaka, 21.7%, and basophils (Kigali, 22.2%.Seasonality had minimal impact on adult clinical laboratory parameter values in Rwanda, Zambia, and Uganda. Seasonal variation may not be an important factor in the

  3. Aerosol seasonal variations over urban sites in Ukraine and Belarus according to AERONET and POLDER measurements

    Science.gov (United States)

    Milinevsky, G.; Danylevsky, V.; Bovchaliuk, V.; Bovchaliuk, A.; Goloub, Ph.; Dubovik, O.; Kabashnikov, V.; Chaikovsky, A.; Mishchenko, M.; Sosonkin, M.

    2013-12-01

    The paper presents an investigation of aerosol seasonal variations in several urban sites in the East European region. Our analysis of seasonal variations of optical and physical aerosol parameters is based on the sun-photometer 2008-2012 data from three urban ground-based AERONET sites in Ukraine (Kyiv, Kyiv-AO, and Lugansk) and one site in Belarus (Minsk), as well as on satellite POLDER instrument data for urban areas in Ukraine. Aerosol amount and optical thickness values exhibit peaks in the spring (April-May) and late summer (August), whereas minimum values are seen in late autumn over the Kyiv and Minsk sites. The results show that aerosol fine mode particles are most frequently detected during the spring and late summer seasons. The seasonal variation similarity in the two regions points to the resemblance in basic aerosol sources which are closely related to properties of aerosol particles. However the aerosol amount and properties change noticeably from year to year and from region to region. The analysis of seasonal aerosol optical thickness variations over the urban sites in the eastern and western parts of Ukraine according to both ground-based and POLDER data exhibits the same traits. In particular, over Kyiv, the values of the Angstrom exponent are lower in April of 2011 than in 2009 and 2010, while aerosol optical thickness values are almost the same, which can be explained by an increase in the amount of coarse mode particles in the atmosphere, such as Saharan dust. Moreover, the coarse mode particles prevailed over suburbs and the center of Kyiv during a third of all available days of observation in 2012. In general, the fine and coarse mode particles' modal radii averaged over 2008-2012 range from 0.1 to 0.2 μm and 2 to 5 μm, respectively, during the period from April to September. The single scattering albedo and refractive index values of these particles correspond to a mix of urban-industrial, biomass burning, and dust aerosols. In addition

  4. Seasonal mortality variations of cardiovascular, respiratory and malignant diseases in the City of Belgrade

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    Stanišić-Stojić Svetlana

    2016-01-01

    Full Text Available The main purpose of this paper is to examine seasonal variations in mortality resulting from cardiovascular diseases, respiratory diseases and cancer, as well as to provide a review of environmental factors underlying such phenomenon. The herein presented study was conducted on the territory of Belgrade based on the data on daily mortality rates obtained from the Institute of Public Health in Belgrade for the period 2009-2014, as well as the data on annual mortality rates provided by the Statistical Office of the Republic of Serbia for the period 2000-2014. The analysis of mortality variations was performed by the use of Theil-Sen method, smooth trend method and cubic spline interpolation, whereas desriptive tools, such as winter/summer ratio and dissimilarity index, were used to examine the seasonal pattern. According to the Institute of Public Health, over 113430 deaths were registered in Belgrade area for the period 2009-2014, out of which 53.25% is attributed to cardiovascular diseases, 4.01% to respiratory diseases and 27.50% to cancer. The annual mortality rates caused by cardiovascular diseases and cancer on the territory of Belgrade are among the highest ranking in Europe. The leading causes of death in the observed period included: cardiomyopathy, heart attack and stroke with accompanying complications, breast cancer in women, prostate and colorectal cancer in men, lung and bronchus cancer for both genders, and chronic obstructive pulmonary disease. Cardiovascular and respiratory mortality rates are significantly higher among people aged 65 and over, whereas more than one third of deaths caused by cancer is observed among younger people aged between 45 and 64 years. Research results show that seasonal variations were most pronounced in mortality resulting from cardiovascular and respiratory diseases, with highest mortality rates recorded in February and March and lowest during the summer season. Also, the number of deaths due to

  5. Seasonal and interannual variations of mixed layer salinity in the southeast tropical Indian Ocean

    Science.gov (United States)

    Zhang, Ningning; Feng, Ming; Du, Yan; Lan, Jian; Wijffels, Susan E.

    2016-07-01

    In this study, seasonal and interannual variations of the mixed layer salinity (MLS) in the southeast tropical Indian Ocean (SETIO) are analyzed using satellite observations, historical data sets, and data-assimilating ocean model outputs. On the seasonal cycle, the MLS in the SETIO becomes fresher in austral winter and saltier in austral summer: between the Java-Lesser Sunda coast and the South Equatorial Current (SEC, 12°S), where positive entrainment and fresh advections counterbalance each other, the annual cycle of the MLS closely follows the variation of the air-sea freshwater forcing; off the northwest and west Australian coasts, the MLS variations are influenced by the annual cycles of the Indonesian Throughflow (ITF) and Leeuwin Current (LC) transports as well as the air-sea freshwater forcing, with eddy fluxes acting to freshen the MLS along the SEC, the Eastern Gyral Current, and the LC. On the interannual-scale, El Niño (La Niña) events are typically associated with saltier (fresher) MLS in the SETIO. Composite and budget analyses reveal that interannual variations in precipitations drive the MLS anomalies off the Java-Lesser Sunda coast; between 12°S and the northwest Australian coast, the MLS variations are influenced by both advection anomalies and local precipitation anomalies; whereas anomalous meridional currents contribute to the MLS variations off the west Australian coast. Both enhanced local precipitations and the ITF transport anomalies have substantial contributions to the drastic freshening of the Indonesian-Australian Basin between the Java-Lesser Sunda coast and the northwest Australian coast during the extended La Niña events in 1999-2001 and 2010-2012.

  6. Frequency of typhoid fever and its association with seasonal variations in Taxila, Pakistan

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    Naeem Bukhari

    2016-08-01

    Full Text Available Objective: To analyse seropositivity rates of salmonella with seasonal variations in the population of Taxila and the surrounding rural areas. Methods: The study was conducted among 760 suspected patients with symptoms of fever, headache, nausea and decreased white blood cells count screened for the typhoid fever. Blood samples collected from the suspected patients were tested for seropositivity by slide agglutination (Widal test and Immunochromatographic test, i.e. Typhidot. Results: From overall 760 suspected patients of typhoid fever only 192 (25.26% samples were positive for Widal and Typhidot test. The peak seropositivity rates were identified during the months of April–June, while decreased cases were observed from January to March. Age wise distribution of typhoid fever reflected that age groups of 10–15 years and 25–35 years were at higher risks of developing enteric fever with respect to age groups of 5–10 years and 61–70 years, respectively. On gender basis evaluation, females (24.49% were slightly at low risks of developing typhoid fever than males (25.9%. Conclusions: The present study highlights a higher burden of typhoid fever in Taxila and the surrounding areas population that directly reflects the poor hygienic condition and contamination of drinking water. The frequency of typhoid fever fluctuates with seasonal variations as higher rates found during the summer as compared to winter season.

  7. Season-induced variation in lipid composition is associated with semen quality in Holstein bulls.

    Science.gov (United States)

    Argov-Argaman, N; Mahgrefthe, K; Zeron, Y; Roth, Z

    2013-05-01

    Season-induced variation in fatty acid and cholesterol composition in bovine semen has been associated with semen quality. Given the specific roles of the various semen compartments (seminal fluids, sperm head, and sperm tail) in fertilization, we hypothesized that environmental-stress-induced alterations in the lipid composition of a specific compartment might impair semen quality and sperm function. Semen samples were collected from five mature Holstein-Friesian bulls during the summer (August to September) and winter (December to January). Semen was evaluated by computerized sperm-quality analyzer, calibrated for bulls' semen, and centrifuged to separate the spermatozoa from the seminal fluids. The spermatozoal fraction was sonicated to separate the sperm head and tail compartments. Cold lipid extraction was performed with chloroform:methanol (2:1, vol/vol). Lipids were identified and quantified by gas chromatography. Seasonal variation was found in both physiological and structural parameters. The proportion of spermatozoa defined as morphologically normal was higher in the winter, with higher motility, progressive motility, and velocity relative to summer samples. Lipid composition within fractions varied between seasons with prominent impairment in the tail compartment, characterized by high saturated fatty acid, low polyunsaturated fatty acid, and low cholesterol concentrations during the summer. Given the association between alterations in lipid composition and reduced sperm motility and velocity during the summer, it is suggested that lipid composition might serve to predict sperm quality.

  8. Seasonal Variation of Harbor Seal's Diet from the Wadden Sea in Relation to Prey Availability

    Science.gov (United States)

    de la Vega, Camille; Lebreton, Benoit; Siebert, Ursula; Guillou, Gael; Das, Krishna; Asmus, Ragnhild; Asmus, Harald

    2016-01-01

    The Wadden Sea has an important role for marine mammals in terms of resting, nursing and foraging. Harbor seal is the most abundant marine mammal species in this area. The use of the food resources of the Wadden Sea by seals is not clear, and previous studies showed that this species can travel kilometers away from their haul-outs to forage in the North Sea. In this study, we analyzed the stable isotopes of vibrissae from 23 dead harbor seals found on the island of Sylt to investigate their diet. The predator´s carbon and nitrogen isotope compositions were compared to the compositions of different potential prey items from the Sylt-Rømø Bight and from the North Sea in order to study seasonal pattern in the diet and in the foraging location. In parallel, seasonal variation of abundance and biomass of the potential prey items from the Sylt-Rømø Bight were studied and compare to their contribution to the seal´s diet. The results revealed a change in the seal´s diet from pelagic sources in spring to a benthic based diet in summer, and an increasing use of the North Sea resources in fall and winter in accordance with the seasonal variation of the availability of prey in the Sylt-Rømø Bight. PMID:27176227

  9. Seasonal variation in the antifouling defence of the temperate brown alga Fucus vesiculosus.

    Science.gov (United States)

    Saha, Mahasweta; Wahl, Martin

    2013-01-01

    The important role of marine epibiotic biofilms in the interactions of the host with its environment has been acknowledged recently. Previous studies with the temperate brown macroalga Fucus vesiculosus have identified polar and non-polar compounds recovered from the algal surface that have the potential to control such biofilms. Furthermore, both the fouling pressure and the composition of the epibiotic bacterial communities on this macroalga varied seasonally. The extent to which this reflects a seasonal fluctuation of the fouling control mechanisms of the host is, however, unexplored in an ecological context. The present study investigated seasonal variation in the anti-settlement activity of surface extracts of F. vesiculosus against eight biofilm-forming bacteria isolated from rockweed-dominated habitats, including replication of two populations from two geographically distant sites. The anti-settlement activity at both sites was found to vary temporally, reaching a peak in summer/autumn. Anti-settlement activity also showed a consistent and strong difference between sites throughout the year. This study is the first to report temporal variation of antifouling defence originating from ecologically relevant surface-associated compounds.

  10. Spatial and seasonal variations of the contamination within water body of the Grand Canal, China

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xiaolong, E-mail: wangxl@niglas.ac.c [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences (China); Han Jingyi [Environmental Policy Group, Department of Social Sciences, Wageningen University, Hollandseweg 1, 6706 KN Wageningen (Netherlands); Xu Ligang; Zhang Qi [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences (China)

    2010-05-15

    To delineate the character of contaminations in the Grand Canal, China, a three-year study (2004-2006) was conducted to investigate variations the water quality in the canal. Results showed that the variation of water quality within the Grand Canal was of there is remarkable spatial and seasonal heterogeneity regarding water quality within the Canal. Values of contaminants in dry-season were obviously higher than those in wet-season. Sites influenced strongly by industry and urbanization showed higher contents of nutrients and lower levels of dissolved oxygen in water body; moreover these sites were severely polluted by dissolved metals with the contents of cadmium, chromium and copper exceeding the Criteria Maximum Concentration (CMC), US EPA. Multivariate statistical analysis suggested nutrient and dissolved metals pollution was the dominant environmental problems within the Canal. Anthropogenic influences played a dominant role in the character of contaminations in the Grand Canal. - The Grand Canal has been severely polluted by dissolved metals and nutrient due to anthropogenic activities

  11. Man biting rate seasonal variation of malaria vectors in Roraima, Brazil

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    Fábio Saito Monteiro de Barros

    2007-06-01

    Full Text Available Malaria control has been directed towards regional actions where more detailed knowledge of local determinants of transmission is of primary importance. This is a short report on range distribution and biting indices for Anopheles darlingi and An. albitarsis during the dry and rainy season that follows river level variation in a savanna/alluvial forest malaria system area in the Northern Amazon Basin. Distribution range and adult biting indices were at their highest during the rainy season for both An. darlingi and An. albitarsis. During the rainy season the neighboring alluvial forest was extensively flooded. This coincided with highest rates in malaria transmission with case clustering near the river. As the river receded, anopheline distribution range and density decreased. This decrease in distribution and density corresponded to a malaria decrease in the near area. An exponential regression function was derived to permit estimations of An. darlingi distribution over specified distances. Anopheline spatio-temporal variations lead to uneven malaria case distribution and are of important implications for control strategies.

  12. Seasonal Variation of δ13C of Four Tree Species: A Biological Integrator of Environmental Variables

    Institute of Scientific and Technical Information of China (English)

    Hai-Tao LI; Jun XIA; Le XIANG; Tao LIANG; Qi-Jing LIU

    2005-01-01

    Foliar δ13C values, an indicator of long-term intercellular carbon dioxide concentration and, thus,of long-term water use efficiency (WUE) in plants, were measured for Pinus massoniana Lamb., P. elliottii Engelm., Cunninghamia laceolata (Lamb.) Hook., and Schima superba Gardn. et Champ. in a restored forest ecosystem in the Jiazhu River Basin. Seasonal variation and the relationship between the foliar δ13Cvalues of the four species and environmental factors (monthly total precipitation, monthly average air temperature, relative humidity, atmospheric pressure, and monthly total solar radiation and evaporation)were investigated. The monthly δ13C values and WUE of the four species increased with increasing precipitation, air temperature, solar radiation, and evaporation, whereas δ13C values of the four species decreased with increasing relative humidity and atmospheric pressure. Despite significant differences in δ13C seasonal means for the four species, our results demonstrate a significant convergence in the responses of δ13C values and WUE to seasonal variations in environmental factors among the species investigated and that the δ13C signature for each species gives a strong indication of environmental variables.

  13. Epsodic paroxysmal hemicrania with seasonal variation: case report and the EPH-cluster headache continuum hypothesis

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    Veloso Germany Gonçalves

    2001-01-01

    Full Text Available Episodic paroxysmal hemicrania (EPH is a rare disorder characterized by frequent, daily attacks of short-lived, unilateral headache with accompanying ipsilateral autonomic features. EPH has attack periods which last weeks to months separated by remission intervals lasting months to years, however, a seasonal variation has never been reported in EPH. We report a new case of EPH with a clear seasonal pattern: a 32-year-old woman with a right-sided headache for 17 years. Pain occurred with a seasonal variation, with bouts lasting one month (usually in the first months of the year and remission periods lasting around 11 months. During these periods she had headache from three to five times per day, lasting from 15 to 30 minutes, without any particular period preference. There were no precipitating or aggravating factors. Tearing and conjunctival injection accompanied ipsilaterally the pain. Previous treatments provided no pain relief. She completely responded to indomethacin 75 mg daily. After three years, the pain recurred with longer attack duration and was just relieved with prednisone. We also propose a new hypothesis: the EPH-cluster headache continuum.

  14. Analysis of trends and seasonal variation in primary cutaneous melanoma: an Irish study.

    LENUS (Irish Health Repository)

    Downes, M R

    2010-11-10

    A seasonal variation in the presentation of cutaneous melanoma has been documented in several studies. We performed a retrospective review of primary cutaneous melanomas (n = 263) from our institution to examine whether the seasonal patterns of presentation noted in the literature would be similar in Ireland, a climate with low ambient sunshine. A summer : winter ratio was determined for age, gender, subtype, location and Breslow thickness. We found an increase in total numbers of melanomas, particularly in men. The summer : winter ratio was 2.39 for all patients (95% CI 1.60-3.57, P < 0.001), with seasonal variations noted for location, thickness and subtype (excluding lentigo). Melanomas presenting over the summer tended towards a greater Breslow thickness than did those presenting in winter. This subclassification of primary cutaneous melanoma with summer : winter ratios based on patient and tumour characteristics gave remarkably similar results to previously published reports, notwithstanding the low levels of annual ambient sunshine in Ireland.

  15. Seasonal variation of Legionella in Taiwan's reservoir and its relationships with environmental factors.

    Science.gov (United States)

    Kao, Po-Min; Hsu, Bing-Mu; Chang, Tien-Yu; Hsu, Tsui-Kang; Tzeng, Kai-Jiun; Huang, Yu-Li

    2015-04-01

    In this study, the presence of Legionella in major water reservoirs of Taiwan was examined with respect to seasonal variation, geographical variation, and water quality parameters using TaqMan real-time qPCR. Water samples were collected quarterly at 19 reservoirs in Taiwan between November 2012 and August 2013. The detection rate for Legionella was 35.5% (27/76), and Legionella was detected in all seasons. The Legionella concentration was relatively high in spring and summer, reaching 3.86 × 10(8) and 7.35 × 10(8) cells/L, respectively. By sampling the area, Legionella was detected at a higher proportion in reservoirs in the northern and southern areas, and the difference was consistent in all seasons. Significant association was found between detection of Legionella and various water quality parameters, including conductivity, chlorophyll a, and dissolved oxygen (Mann-Whitney U test, P Legionella detection with pH (P = 0.030, R = -0.497) and dissolved oxygen (P = 0.007, R = -0.596) in fall and positive correlation with Carlson's trophic state index (P = 0.049, R = 0.457) in spring. The identified species included Legionella pneumophila and Legionella drancourtii. The detection of Legionella in reservoirs was indicative of a potential public health risk and should be further evaluated.

  16. Seasonal variation of serum vitamin D among Greek female patients with osteoporosis.

    Science.gov (United States)

    Papadakis, Georgios; Keramidas, Ioannis; Kakava, Kassiani; Pappa, Theodora; Villiotou, Vassiliki; Triantafillou, Eleni; Drosou, Aspasia; Tertipi, Athanasia; Kaltzidou, Victoria; Pappas, Anastasios

    2015-01-01

    Vitamin D (vitD) levels are positively associated with bone health and seasonality affects serum vit D. The aim of the study was to investigate the degree of seasonal variation on 25-hydroxyvitamin D (25(OH)D) serum levels in a population-based cohort of post-menopausal women with osteoporosis. Serum levels of 25(OH)D were assessed in 596 patients (mean age=65.3 years; standard deviation (SD)=9.4) in different time points over a period of 2.5 years. The minimum 25(OH)D serum levels were observed in March (13.4±9.5 ng/ml) and the maximum levels in August, September and October (29.1±16.1, 28.9±12 and 28.4±8.9 ng/ml, respectively). The prevalence of vitD deficiency, insufficiency and sufficiency in March was 76.5, 15.7 and 7.8%, respectively. On the contrary, the highest prevalence of vitD sufficiency was observed in August, September and October (38.1%, 45.3% and 46.5%, respectively). Seasonal variations should be considered when measuring for 25(OH)D serum levels and treating vitD deficiency. Copyright © 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  17. Seasonal Variation of Harbor Seal's Diet from the Wadden Sea in Relation to Prey Availability.

    Directory of Open Access Journals (Sweden)

    Camille de la Vega

    Full Text Available The Wadden Sea has an important role for marine mammals in terms of resting, nursing and foraging. Harbor seal is the most abundant marine mammal species in this area. The use of the food resources of the Wadden Sea by seals is not clear, and previous studies showed that this species can travel kilometers away from their haul-outs to forage in the North Sea. In this study, we analyzed the stable isotopes of vibrissae from 23 dead harbor seals found on the island of Sylt to investigate their diet. The predator´s carbon and nitrogen isotope compositions were compared to the compositions of different potential prey items from the Sylt-Rømø Bight and from the North Sea in order to study seasonal pattern in the diet and in the foraging location. In parallel, seasonal variation of abundance and biomass of the potential prey items from the Sylt-Rømø Bight were studied and compare to their contribution to the seal´s diet. The results revealed a change in the seal´s diet from pelagic sources in spring to a benthic based diet in summer, and an increasing use of the North Sea resources in fall and winter in accordance with the seasonal variation of the availability of prey in the Sylt-Rømø Bight.

  18. Seasonal and Spatial Variations of Heavy Metals in Two Typical Chinese Rivers: Concentrations, Environmental Risks, and Possible Sources

    Directory of Open Access Journals (Sweden)

    Hong Yao

    2014-11-01

    Full Text Available Ten metals were analyzed in samples collected in three seasons (the dry season, the early rainy season, and the late rainy season from two rivers in China. No observed toxic effect concentrations were used to estimate the risks. The possible sources of the metals in each season, and the dominant source(s at each site, were assessed using principal components analysis. The metal concentrations in the area studied were found, using t-tests, to vary both seasonally and spatially (P = 0.05. The potential risks in different seasons decreased in the order: early rainy season > dry season > late rainy season, and Cd was the dominant contributor to the total risks associated with heavy metal pollution in the two rivers. The high population and industrial site densities in the Taihu basin have had negative influences on the two rivers. The river that is used as a source of drinking water (the Taipu River had a low average level of risks caused by the metals. Metals accumulated in environmental media were the main possible sources in the dry season, and emissions from mechanical manufacturing enterprises were the main possible sources in the rainy season. The river in the industrial area (the Wusong River had a moderate level of risk caused by the metals, and the main sources were industrial emissions. The seasonal and spatial distributions of the heavy metals mean that risk prevention and mitigation measures should be targeted taking these variations into account.

  19. Seasonal variation of some physical features of the coastal waters off Waltair

    Directory of Open Access Journals (Sweden)

    V.V.R. Varadachari

    1963-04-01

    Full Text Available The seasonal variation of temperature, density and transparency of the coastal waters off Waltair has been studied with the help of the data obtained on the oceanographic cruises of the Andhra University. The study reveal the following results. The surface temperature is lowest in December and highest in September. The annual range of temperature is not maximum at the surface but at some depth. In the surface layers, positive temperature gradients occur during the winter months and negative gradients during the remaining period of the year. The thermocline gets deeper and deeper during the period September to January and it begins to move up in February. The water undergoes large seasonal change of density at the surface with low values in October and high values in Spring and Summer. The annual range of density decreases with depth in the top fifty meters. The vertical density gradients in the surface layers are small in Spring and Summer and large in the Fall season. The transparency of the waters changes with season and distance from the coast. The nearshore waters are less transparent than those offshore, throughout the year. The most turbid waters for the year are encountered in April and Maya feature related to upwelling near the coast. Sinking during the period September to December and upwelling in Spring and Summer take place in nearshore regions.

  20. Variations in ozone depletion potentials of very short-lived substances with season and emission region

    Science.gov (United States)

    Brioude, J.; Portmann, R. W.; Daniel, J. S.; Cooper, O. R.; Frost, G. J.; Rosenlof, K. H.; Granier, C.; Ravishankara, A. R.; Montzka, S. A.; Stohl, A.

    2010-12-01

    We present a new approach for calculating the fraction of very-short lived substances (VSLS) emitted at the surface (and their degradation products) that reach the stratosphere (β) using the FLEXPART Lagrangian model. The values of β play a key role in determining the efficiency of these compounds for depleting stratospheric ozone, and are used to estimate ozone depletion potentials (ODPs) for several short-lived compounds. Values of β and ODPs of VSLSs are characterized by large regional and seasonal variability owing to the importance of convective transport. For instance, β and ODPs associated with emissions from the Indian subcontinent is an order of magnitude larger than from Europe, mid-latitude North America, or East Asia.The seasonal cycle of β is mainly driven by transport efficiency from the boundary layer into the tropical stratosphere with a minimum in winter and a maximum in summer. Variation of fraction of mass of VSLS reaching the stratosphere (β) plotted against the seasonally varying tropospheric lifetime of VSLS. Values of β are calculated for different seasons (panels) and regions of emission (color code). Also shown are the results for VSLS with predominantly photolytic loss (stars) and OH loss (circles).

  1. Prevalence of antibiotic residues in commercial milk and its variation by season and thermal processing methods

    Directory of Open Access Journals (Sweden)

    Fathollah Aalipour

    2013-01-01

    Full Text Available Aims: In this study, the prevalence of antibiotic residues in pasteurized and sterilized commercial milk available in Shahre-kourd, Iran, was investigated. In addition, the influence of seasonal temperature changes on the prevalence of contamination was studied. Materials and Methods: Commercial milk samples of 187, including 154 pasteurized and 33 sterilized, milk samples were collected from the market between early January 2012 and late July of the same year. The presence of antibiotic residues was detected using the microbiological detection test kit, Eclipse 100, as a semi-quantitative method. Results: The results showed that 37 of the samples (19.8% have contained antibiotic residues above the European Union Maximum Residues Limits (EU-MRLs, of which 28 samples (14.97% were found to be contaminated but at the concentrations below the EU-MRLs. There was no significant difference between the contamination rate of pasteurized and Ultra High Temperature (UHT-sterilized samples. Similarly, variation of weather temperature with seasons had no effect on the contamination prevalence of milk samples ( P > 0.05. Conclusion: Based on the result of this study, antibiotics residues were present in the majority of milk samples. Neither the season nor the type of thermal processing of the commercial milks had noticeable impact on the prevalence level of the milk samples. However, an increasing trend of prevalence level for antibiotic residues was observed with increasing the temperature through the warm season.

  2. Seasonal variation in body mass and energy budget in Chinese bulbuls (pycnonotus sinensis)

    Institute of Scientific and Technical Information of China (English)

    Mengsi Wu; Yuchao Xiao; Fang Yang; Limeng Zhou; Weihong Zheng; Jinsong Liu

    2014-01-01

    Background:Seasonal adjustments in body mass and energy budget are important for the survival of small birds in temperate zones. Seasonal changes in body mass, body temperature, gross energy intake (GEI), digestible energy intake (DEI), body fat content, as well as length and mass of the digestive tract, were measured in Chinese Bulbuls (Pycnonotus sinensis) caught in the wild at Wenzhou, China. Methods:Body mass was determined with a Sartorius balance. The caloric contents of the dried food and feces were then determined using a oxygen bomb calorimeter. Total fat was extracted from the dried carcasses by ether extraction in a Soxhlet apparatus. The digestive tract of each bird was measured and weighed, and was then dried to a constant mass. Results:Body mass showed a significant seasonal variation and was higher in spring and winter than in summer and autumn. Body fat was higher in winter than in other seasons. GEI and DEI were significantly higher in winter. The length and mass of the digestive tract were greatest in winter and the magnitude of both these parameters was positively correlated with body mass, GEI and DEI. Small passerines typical y have higher daily energy expenditure in winter, necessitating increased food consumption. Conclusions:This general observation is consistent with the observed winter increase in gut volume and body mass in Chinese Bulbuls. These results suggest that Chinese Bulbuls adjust to winter conditions by increasing their body mass, body fat, GEI, DEI and digestive tract size.

  3. Seasonal variation in body mass and energy budget in Chinese bulbuls (pycnonotus sinensis)

    Institute of Scientific and Technical Information of China (English)

    Mengsi; Wu; Yuchao; Xiao; Fang; Yang; Limeng; Zhou; Weihong; Zheng; Jinsong; Liu

    2014-01-01

    Background: Seasonal adjustments in body mass and energy budget are important for the survival of small birds in temperate zones. Seasonal changes in body mass, body temperature, gross energy intake(GEI), digestible energy intake(DEI), body fat content, as well as length and mass of the digestive tract, were measured in Chinese Bulbuls(Pycnonotus sinensis) caught in the wild at Wenzhou, China.Methods: Body mass was determined with a Sartorius balance. The caloric contents of the dried food and feces were then determined using a oxygen bomb calorimeter. Total fat was extracted from the dried carcasses by ether extraction in a Soxhlet apparatus. The digestive tract of each bird was measured and weighed, and was then dried to a constant mass.Results: Body mass showed a significant seasonal variation and was higher in spring and winter than in summer and autumn. Body fat was higher in winter than in other seasons. GEI and DEI were significantly higher in winter.The length and mass of the digestive tract were greatest in winter and the magnitude of both these parameters was positively correlated with body mass, GEI and DEI. Small passerines typically have higher daily energy expenditure in winter, necessitating increased food consumption.Conclusions: This general observation is consistent with the observed winter increase in gut volume and body mass in Chinese Bulbuls. These results suggest that Chinese Bulbuls adjust to winter conditions by increasing their body mass, body fat, GEI, DEI and digestive tract size.

  4. Seasonal variation in habitat use of juvenile Steelhead in a tributary of Lake Ontario

    Science.gov (United States)

    Studdert, Emily W.; Johnson, James H.

    2015-01-01

    We examined seasonal-habitat use by subyearling and yearling Oncorhynchus mykiss (Rainbow Trout or Steelhead) in Trout Brook, a tributary of the Salmon River, NY. We determined daytime fish-habitat use and available habitat during August and October of the same year and observed differences in habitat selection among year classes. Water depth and cover played the greatest role in Steelhead habitat use. During summer and autumn, we found yearling Steelhead in areas with deeper water and more cover than where we observed subyearling Steelhead. Both year classes sought out areas with abundant cover during both seasons; this habitat was limited within the stream reach. Subyearling Steelhead were associated with more cover during autumn, even though available cover within the stream reach was greater during summer. Principal component analysis showed that variation in seasonal-habitat use was most pronounced for subyearling Steelhead and that yearling Steelhead were more selective in their habitat use than subyearling Steelhead. The results of this study contribute to a greater understanding of how this popular sportfish is adapting to a new environment and the factors that may limit juvenile Steelhead survival. Our findings provide valuable new insights into the seasonal-habitat requirements of subyearling and yearling Steelhead that can be used by fisheries managers to enhance and protect the species throughout the Great Lakes region.

  5. Seasonal variation of serum biochemical values of Amazonian snakes (Boa constrictor constrictor kept in captivity

    Directory of Open Access Journals (Sweden)

    Dennis José da Silva Lima

    2012-11-01

    Full Text Available In northern Brazil, the seasons are not well defined compared to the South and Southeast regions, due to a hot and humid equatorial climate with a rainy season, known as the Amazonian winter, and a period with less rain, known as the Amazonian summer. The goal of this study was to evaluate the biochemical variation of serum from the Amazon Boa constrictor by correlating the values with the seasons of the region. A biochemical analysis of the serum was performed (AST, ALT, LDH, ALP, calcium, uric acid, phosphorus, total protein, albumin and globulin using 31 individuals of Boa constrictor constrictor, which were kept in captivity. It was observed that eight of the ten parameters were higher in the winter compared to the summer (total protein, albumin, globulin, ALT, AST, ALP, LDH and calcium. The ALT, AST and calcium values had statistically significant differences for the summer and winter, while the other parameters appear to be influenced by seasonality. This was the first study of snakes kept in captivity that analyzed the serum chemistry profile of Boa constrictor constrictor from the state of Pará, Brazil.

  6. SHIFTS OF START AND END OF SEASON IN RESPONSE TO AIR TEMPERATURE VARIATION BASED ON GIMMS DATASET IN HYRCANIAN FORESTS

    Directory of Open Access Journals (Sweden)

    K. H. Kiapasha

    2017-09-01

    Full Text Available Climate change is one of the most important environmental challenges in the world and forest as a dynamic phenomenon is influenced by environmental changes. The Hyrcanian forests is a unique natural heritage of global importance and we need monitoring this region. The objective of this study was to detect start and end of season trends in Hyrcanian forests of Iran based on biweekly GIMMS (Global Inventory Modeling and Mapping Studies NDVI3g in the period 1981-2012. In order to find response of vegetation activity to local temperature variations, we used air temperature provided from I.R. Iran Meteorological Organization (IRIMO. At the first step in order to remove the existing gap from the original time series, the iterative Interpolation for Data Reconstruction (IDR model was applied to GIMMS and temperature dataset. Then we applied significant Mann Kendall test to determine significant trend for each pixel of GIMMS and temperature datasets over the Hyrcanian forests. The results demonstrated that start and end of season (SOS & EOS respectively derived from GIMMS3g NDVI time series increased by -0.16 and +0.41 days per year respectively. The trends derived from temperature time series indicated increasing trend in the whole of this region. Results of this study showed that global warming and its effect on growth and photosynthetic activity can increased the vegetation activity in our study area. Otherwise extension of the growing season, including an earlier start of the growing season, later autumn and higher rate of production increased NDVI value during the study period.

  7. Seasonal dynamics of CO{sub 2} exchange during primary succession of boreal mires as controlled by phenology of plants

    Energy Technology Data Exchange (ETDEWEB)

    Leppala, M.; Kukko-Oja, K. [Finnish Forest Research Inst., Muhos (Finland); Laine, J. [Finnish Forest Research Inst., Parkano (Finland); Tuittila, E.S. [Helsinki Univ., Helsinki (Finland). Dept. of Forest Ecology, Peatland Ecology Group

    2008-07-01

    Seasonal dynamics in vegetation and carbon dioxide (CO{sub 2}) exchange were studied at 5 small mire basins along a chronosequence from the initial stages of paludification through to the bog stage in the Bay of Bothnia region in Finland. Precipitation and mean temperature during the summer 2004 study season were measured at a nearby meteorological station. Plant community composition was determined by estimating the projection cover of each species. Subplots in each of the study sites were established to count the number of living leaves of all vascular plant species. Sample plots were surrounded by aluminum collars in order to facilitate CO{sub 2} exchange measurements. Infrared gas analyzers were used to measure CO{sub 2} concentrations. Seasonal estimates of CO{sub 2} exchange dynamics were modelled in order to quantify the importance of different functional plant groups during the mire successions. Results of the study showed that seasonal variations in plant phenology and ecosystem respiration decreased in older sites along a mire chronosequence. Photosynthetically effective groups such as sedges and graminoids determined most of the seasonal CO{sub 2} dynamics. The higher level of gross photosynthesis combined with lower ecosystem respiration made the younger successional stages the largest sinks of atmospheric CO{sub 2}. Results suggested that autogenic factors controlled both the level and variation of CO{sub 2} exchange during mire succession. It was concluded that changes in vegetation must be considered when developing dynamic carbon models for mires of different ages, peat depths, and successional stages. 61 refs., 3 tabs., 8 figs.

  8. Seasonal and annual variation of CO2 flux above a broad-leaved Korean pine mixed forest

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    <正>Long-term measurement of carbon metabolism of old-growth forests is critical to predict their behaviors and to reduce the uncertainties of carbon accounting under changing climate. Eddy covariance technology was applied to investigate the long-term carbon exchange over a 200 year-old Chinese broad-leaved Korean pine mixed forest in the Changbai Mountains (128°28’E and 42°24’N, Jilin Province, P. R. China) since August 2002. On the data obtained with open-path eddy covariance system and CO2 profile measurement system from Jan. 2003 to Dec. 2004, this paper reports (i) annual and seasonal variation of FNEE, FGPP and Re; (ii) regulation of environmental factors on phase and amplitude of ecosystem CO2 uptake and release Corrections due to storage and friction velocity were applied to the eddy carbon flux. Lal and soil temperature determined the seasonal and annual dynamics of FGPP and RE separately. VPD and air temperature regulated ecosystem photosynthesis at finer scales in growing seasons. Water condition at the root zone exerted a significant influence on ecosystem maintenance carbon metabolism of this forest in winter. The forest was a net sink of atmospheric CO2 and sequestered -449 g C·m-2 during the study period; -278 and -171 gC·m-2 for 2003 and 2004 respectively. FGPP and FRE over 2003 and 2004 were -1332, -1294 g C·m-2. and 1054, 1124 g C·m-2 respectively. This study shows that old-growth forest can be a strong net carbon sink of atmospheric CO2. There was significant seasonal and annual variation in carbon metabolism. In winter, there was weak photosynthesis while the ecosystem emitted CO2. Carbon exchanges were active in spring and fall but contributed little to carbon sequestration on an annual scale. The summer is the most significant season as far as ecosystem carbon balance is concerned. The 90 days of summer contributed 66.9, 68.9% of FGPp, and 60.4, 62.1% of RE of the entire year.

  9. Seasonal Dynamics of Ant Community Structure in the Moroccan Argan Forest

    Science.gov (United States)

    Keroumi, Abderrahim El; Naamani, Khalid; Soummane, Hassna; Dahbi, Abdallah

    2012-01-01

    In this study we describe the structure and composition of ant communities in the endemic Moroccan Argan forest, using pitfall traps sampling technique throughout the four seasons between May 2006 and February 2007. The study focused on two distinct climatic habitats within the Essaouira Argan forest, a semi-continental site at Lahssinate, and a coastal site at Boutazarte. Thirteen different ant species were identified, belonging to seven genera. Monomorium subopacum Smith and Tapinoma simrothi Krausse-Heldrungen (Hymenoptera: Formicidae) were the most abundant and behaviorally dominant ant species in the arganeraie. In addition, more specimens were captured in the semi-continental site than in the coastal area. However, no significant difference was observed in species richness, evenness, or diversity between both sites. Composition and community structure showed clear seasonal dynamics. The number of species, their abundance, their diversity, and their evenness per Argan tree were significantly dissimilar among seasons. The richness (except between summer and autumn), and the abundance and the evenness of ant species among communities, showed a significant difference between the dry period (summer and spring) and the rainy period (winter and autumn). Higher abundance and richness values occurred in the dry period of the year. Ant species dominance and seasonal climatic variations in the arganeraie might be among the main factors affecting the composition, structure, and foraging activity of ant communities. This study, together with recent findings on ant predation behavior below Argan trees, highlights the promising use of dominant ant species as potential agents of Mediterranean fruit fly bio-control in the Argan forest and surrounding ecosystems. PMID:23421815

  10. Studies on seasonal and topographical variations of periphyton in the rivers of Manipur.

    Science.gov (United States)

    Gurumayum, S D; Goswami, U C

    2013-05-01

    Seasonal and topographical variations of abundance and quality composition of periphyton at up and down stream of Imphal, Thoubal and Khuga rivers were studied from 1999-2002. It was found that periphyton population was high (3,055-53,450 u cm(-2)) and fluctuated in a wide range. Upper stretches (3053-53,450 u cm(-2)) of the rivers have higher periphyton population and showed definite seasonal fluctuation than the middle and lower stretches (3,276-16,320 u cm2). Species richness was also higher in upper stretches in comparison to lower stretches of all the rivers. Bacillariophyceae dominated the periphyton population and contribution of Cyanophyceae was nominal. Shannon and Weaver species diversity index was within the favorable range and evenness value for all the rivers were near unity and reflected a stable and unpolluted aquatic environment of the rivers.

  11. Seasonal variations in the concentrations of metals in Crassostrea corteziensis from Sonora, México.

    Science.gov (United States)

    García-Rico, L; Tejeda-Valenzuela, L; Burgos-Hernández, A

    2010-08-01

    This study examines seasonal variations in the concentrations of Cd, Cu, Pb, and Hg in experimentally cultured Crassostrea corteziensis, an oyster species known to have high resistance to physical and chemical stressors. The highest levels of Cd (4.92 mg/kg), Cu (3.45 mg/kg), and Pb (0.67 mg/kg) were detected in oyster samples collected during the summer, while Hg concentrations were similar (0.03 to 0.04 mg/kg) throughout all seasons. Results indicate that except for Cd, Crassostrea corteziensis accumulates metals to levels below those recommended by the US. FDA and the Mexican government. For Cd, its concentration correlates more strongly with the temperature of the oyster's environment rather than to the oyster growth cycle.

  12. Occurrence, seasonal variation and risk assessment of antibiotics in the reservoirs in North China.

    Science.gov (United States)

    Li, Nan; Zhang, Xinbo; Wu, Wei; Zhao, Xinhua

    2014-09-01

    The occurrence and seasonal variability of five groups (tetracycline, quinolone, chloramphenicol, macrolide and sulfonamide) of antibiotics were investigated in the surface water of four reservoirs. The dissolved concentrations of 29 antibiotics were in the ngL(-1) level. Trace levels of all target antibiotics were analyzed using solid-phase extraction followed by liquid chromatography electrospray tandem mass spectrometry. All of the antibiotics were detected at all sampling sites, indicating widespread occurrence of antibiotics in the study area. The detection of florfenicol, josamycin, kitasamycin, spiramycin and sulfameter is the first report of these compounds in reservoir samples. The results showed an association between the presence of some antibiotics at Panjiakou reservoir and cage culture of fish. Twenty-three types of antibiotics showed significant seasonal variations (pantibiotics detected could cause very low risk to algae, daphnid and fish. Further health risk need to be investigated because these reservoirs are drinking water sources.

  13. THE EVALUATION OF FREQUENCY AND SEASONAL VARIATIONS OF ACID PEPTIC DISEASE: A SEVEN YEARS STUDY

    Directory of Open Access Journals (Sweden)

    Syed Iftikhar Haider

    2016-06-01

    Full Text Available Acid peptic disease (APD is a worldwide health problem. It includes a variety of inflammatory and ulcerative lesions involving esophagus, stomach and duodenum. The disease condition may persist with multiple symptoms, one of them being dyspepsia. The object of the present study was to determine the frequency and seasonal variations of APD in patients presenting with dyspeptic symptoms. This observational study was carried out at the endoscopy unit in Baqai Medical University from December 2003 to December 2010, over a period of seven years. The evolution of APD frequency remained equivocal throughout the study period. However, a decline was noted in the frequency of peptic ulcer disease (PUD especially for gastric and duodenal ulcer cases but a rise during autumn and winter seasons was also noted in duodenal ulcer cases.

  14. Seasonal variation of technetium-99 in Fucus vesiculosus and its application as an oceanographic tracer

    Science.gov (United States)

    Shi, Keliang; Hou, Xiaolin; Roos, Per; Wu, Wangsuo; Nielsen, Sven P.

    2013-07-01

    The concentration of 99Tc was determined in archived time series seaweed samples collected at Klint (Denmark). The results demonstrate a significantly seasonal variation of 99Tc concentrations in Fucus vesiculosus with maximum values in winter and minimum values in summer. The mechanism driving this seasonal cycle was explored. With the measured 99Tc concentration in seawater collected in the same location and date as for seaweed, the concentration factor of F. vesiculosus to 99Tc was investigated. Constant value of concentration factors of 99Tc independence of sampling date, with an average value of (1.9 ± 0.5) × 105 L/kg, were obtained. This indicates that F. vesiculosus can be used as a reliable bio-indicator to monitor 99Tc concentration in seawater.

  15. Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

    Science.gov (United States)

    Yizengaw, Endawoke; Carter, Brett A.

    2017-04-01

    It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ). The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998-2014) of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian) have been analyzed. All observations performed during magnetically active periods (Kp>3) have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

  16. Seasonal variation in the behavior of tailing wastes in Buyat Bay, Indonesia.

    Science.gov (United States)

    Prisetiahadi, Kus; Yanagi, Tetsuo

    2008-01-01

    Seasonal variations in temperature, salinity, sigma-t and light transmittance were investigated in Buyat Bay, Indonesia, related to the dumping activity there. More than 2000 tons per day of tailings were disposed through a Submarine Tailing Disposal (STD) method at 82 m depth in Buyat Bay. An 80 m depth of the assumed pycnocline was not well confirmed. The seasonal variability of temperature, salinity and sigma-t showed the pycnocline of 40 m to 135 m at the deepest observation station (140 m) during 1997. Furthermore, the Mixed Layer Depth was in good agreement with the wind stress, and the wind stress affected the spreading of tailings there. The outlet of submarine tailing disposal must be below 135 m in Buyat Bay.

  17. Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

    Energy Technology Data Exchange (ETDEWEB)

    Yizengaw, Endawoke [Boston College, Chestnut Hill, MA (United States). Inst. for Scientific Research; Carter, Brett A. [RMIT Univ., Melbourne, VIC (Australia). SPACE Research Centre

    2017-07-01

    It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ). The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998-2014) of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian) have been analyzed. All observations performed during magnetically active periods (K{sub p}>3) have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

  18. Seasonal and Ontogenetic Variation in Subcutaneous Adipose Of the Bowhead Whale (Balaena mysticetus).

    Science.gov (United States)

    Ball, Hope C; Stavarz, Madeline; Oldaker, Jonathan; Usip, Sharon; Londraville, Richard L; George, John C; Thewissen, Johnannes G M; Duff, Robert Joel

    2015-08-01

    Cetacean evolution was shaped by an extraordinary land-to-sea transition in which the ancestors of whales became fully aquatic. As part of this transition, these mammals evolved unusually thick blubber which acts as a metabolic reservoir as well as an insulator and provides buoyancy and streamlining. This study describes blubber stratification and correlates it to seasonal variation, feeding patterns, and ontogeny in an arctic-adapted mysticete, the bowhead whale (Balaena mysticetus). Bowheads are unique among mammals for possessing the largest known blubber stores. We found that adipocyte numbers in bowheads, like other mammals, do not vary with season or feeding pattern but that adipocyte size and structural fiber densities do vary with blubber depth.

  19. Seasonal variations in halides in marine brown algae from Porbandar and Okha coasts (NW coast of India)

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, Ch.K.; Singbal, S.Y.S.

    Seasonal variation of halides and their ratios were estimated in three brown algae, namely Cystoseira indica, Sargassum tenerrimum) and S. johnstonii from Porbandar and Okha Coasts. Halides were found to be higher in early stages of growth. The Br...

  20. Seasonal variation in sensitivity of larval sea lampreys to the lampricide 3-trifluoromethyl-4-nitrophenol

    Science.gov (United States)

    Scholefield, R.J.; Slaght, K.S.; Stephens, B.E.

    2008-01-01

    We evaluated the sensitivity of larval sea lampreys Petromyzon marinus to the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) in a series of toxicity tests in spring and summer. Although noted previously, the seasonal variation in sensitivity to TFM had never been tested as a means of reducing TFM usage in stream treatments. A preliminary study consisted of three spring and four summer static toxicity tests conducted at 12??C. A more comprehensive study consisted of 12 spring and summer paired flow-through toxicity tests conducted both at seasonal water temperatures and at 12??C. The sensitivity of larval sea lampreys to TFM was greater in spring than in summer. The preliminary static toxicity tests indicated that the concentration of TFM needed to kill larval sea lampreys in spring (May and June) was about one-half that required in summer (August); the concentrations lethal to 50% and 99.9% of the test animals (the LC50 and LC99.9 values) were less in spring than in summer. Analysis of variance of the flow-through toxicity data indicated that season significantly affected both the LC50 and LC99.9 values. For all 12 paired flow-through toxicity tests, the spring LC50 and LC99.9 values were less than the corresponding summer values. For 9 of the 12 paired flow-through toxicity tests, the dose-response toxicity lines were parallel and allowed statistical comparison of the LC50 values. The spring LC50 values were significantly lower than the summer values in eight of the nine tests. Verification of a seasonal variation in the sensitivity of larval sea lampreys to TFM will allow inclusion of this factor in the selection model currently used by both the U.S. Fish and Wildlife Service and the Department of Fisheries and Oceans-Canada to schedule lampricide stream treatments. ?? Copyright by the American Fisheries Society 2008.

  1. Seasonal variation in the titers and biosynthesis of the primer pheromone ethyl oleate in honey bees.

    Science.gov (United States)

    Castillo, Carlos; Maisonnasse, Alban; Conte, Yves Le; Plettner, Erika

    2012-08-01

    Honey bees allocate tasks along reproductive and non-reproductive lines: the queen mates and lays eggs, whereas the workers nurse the brood and forage for food. Among workers, tasks are distributed according to age: young workers nurse and old workers fly out and forage. This task distribution in the colony is further regulated by an increase in juvenile hormone III as workers age and by pheromones. One such compound is ethyl oleate (EO), a primer pheromone that delays the onset of foraging in young workers. EO is produced by foragers when they are exposed to ethanol (from fermented nectar) while gathering food. EO is perceived by younger bees via olfaction. We describe here the seasonal variation of EO production and the effects of Methoprene, a juvenile hormone analog. We found that honey bee workers biosynthesize more EO during the growing season than during the fall and winter months, reaching peak levels at late spring or summer. When caged workers were fed with syrup+d(6)-ethanol, labeled EO accumulated in the honey crop and large amounts exuded to the exoskeleton. Exuded levels were high for several hours after exposure to ethanol. Treatment with Methoprene increased the production of EO in worker bees, by speeding up its movement from biosynthetic sites to the exoskeleton, where EO evaporates. Crop fluid from bees collected monthly during the growing season showed a modest seasonal variation of in vitro EO biosynthetic activity that correlated with the dry and sunny periods during which bees could forage. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Seasonal variation of the Sq focus position during 2006-2010

    Science.gov (United States)

    Vichare, Geeta; Rawat, Rahul; Jadhav, Madhavi; Sinha, Ashwini Kumar

    2017-01-01

    In the present paper, the perception of the seasonal variation of the Sq focus position is re-examined during low solar activity period (2006-2010). Equivalent current vectors are plotted for each geomagnetic quiet day (Ap ⩽ 5), using diurnal variations of H and D components measured at the magnetic observatories located in a narrow longitudinal belt of the Indo-Russian region. On the formation of well-defined Sq current loop, the information about the Sq focus is extracted by identifying a pair of neighboring stations with opposite zonal currents and nearby local times with opposite meridional currents. Thus, the method employed here is different from the methods used in earlier studies. Prominent seasonal variations in the Sq focus latitude, as well as in the local time of Sq focus, are observed. It is observed that the Sq focus is located at ∼30 deg in March equinox, but it moves to lower latitudes in the month of September. In winter, it shows large variability and also the formation of clear Sq current loop is less frequent. The local time of Sq focus is at ∼12 LT in March and shifts to ∼10 LT during September. It is clearly evident from the present analysis that the March and September equinoxes behave differently. The dominance of DE3 and semidiurnal waves in the September equinox could be the reason for the observed disparity.

  3. Spatial and seasonal variations in bacterial communities of the Yellow Sea by T-RFLP analysis

    Institute of Scientific and Technical Information of China (English)

    Hongyuan WANG; Xiaolu JIANG; Ya HE; Huashi GUAN

    2009-01-01

    Four typical coastal sites (rocky shore, sandy shore, mud flat shore, and artificial harbor) at the Yellow Sea were chosen to investigate the spatial and seasonal variations in bacterial communities. This was accomplished by using terminal restriction fragment length polymorphism (T-RFLP) analysis of PCR amplified 16S rDNA fragments. Two kinds of tetrameric restriction enzymes, HhaI and MspI, were used in the experiment to depict the bacterial community diversity in different marine environments. It was found that the community compositions digested by the two enzymes separately were different. However, the results of bacterial community diversity derived from them were similar. The MDA analysis results of T-RFLP profiles coming from HhaI and MspI both exhibited a significant seasonal community shift for bacteria and a relatively low spatial variation among the four locations. With HhaI as the sample, the pair wise T-tests also revealed that variations were minor between each pair of marine environments, with R ranging from 0.198 to 0.349. However, the bacterial community structure in the mud flat site depicted a larger difference than each of the other three sites (R ranging from 0.282 to 0.349).

  4. Variations of Endocrine Hormones Concentrations in Tupaia belangeri under Simulated Seasonal Acclimatized: Role of Leptin Sensitivity

    Directory of Open Access Journals (Sweden)

    Zhu, Wan-long

    2013-04-01

    Full Text Available Seasonal variations in endocrine hormones concentrations are important for the survival of small mammals during acclimatization. In order to understand the role of leptin sensitivity on other endocrine hormones concentrations, we examined body mass, serum leptin level, serum insulin, tri-iodothyronine (T 3, thyroxine (T4 and thyroid stimulating hormone (TSH concentrations in Tupaia belangeri under seasonal acclimatized (The simulated temperature and photoperiod in winter: 5°C and SD, 8h:16h Light:Dark; the simulated temperature and photoperiod in summer: 30°C and SD, 16h:8h Light:Dark for 4 weeks. The results showed that body mass, serum leptin level, serum T3, T4 concentrations and T3/T4 showed significant variation, but serum insulin and TSH concentrations showed no variations between treatment group. There were positive correlation between serum leptin level and insulin, T4 concentrations, and were negative correlation between serum leptin level and body mass, T3 concentrations. However, no correlation was found between serum TSH concentrations and serum leptin level. The present results suggested T. belangeri overcome winter thermogenesis challenges by adjusting body mass and endocrine hormones concentrations. Furthermore, leptin may play an potential role in their body mass regulation in T. belangeri.

  5. Modeling gradually changing seasonal variation in count data using state space models: a cohort study of hospitalization rates of stroke in atrial fibrillation patients in Denmark from 1977 to 2011.

    Science.gov (United States)

    Christensen, Anette L; Lundbye-Christensen, Søren; Overvad, Kim; Rasmussen, Lars H; Dethlefsen, Claus

    2012-11-20

    Seasonal variation in the occurrence of cardiovascular diseases has been recognized for decades. In particular, incidence rates of hospitalization with atrial fibrillation (AF) and stroke have shown to exhibit a seasonal variation. Stroke in AF patients is common and often severe. Obtaining a description of a possible seasonal variation in the occurrence of stroke in AF patients is crucial in clarifying risk factors for developing stroke and initiating prophylaxis treatment. Using a dynamic generalized linear model we were able to model gradually changing seasonal variation in hospitalization rates of stroke in AF patients from 1977 to 2011. The study population consisted of all Danes registered with a diagnosis of AF comprising 270,017 subjects. During follow-up, 39,632 subjects were hospitalized with stroke. Incidence rates of stroke in AF patients were analyzed assuming the seasonal variation being a sum of two sinusoids and a local linear trend. The results showed that the peak-to-trough ratio decreased from 1.25 to 1.16 during the study period, and that the times of year for peak and trough changed slightly. The present study indicates that using dynamic generalized linear models provides a flexible modeling approach for studying changes in seasonal variation of stroke in AF patients and yields plausible results.

  6. Seasonal variation in musculoskeletal extremity injuries in school children aged 6-12 followed prospectively over 2.5 years

    DEFF Research Database (Denmark)

    Jespersen, Eva; Holst, René; Franz, Claudia;

    2014-01-01

    The type and level of physical activity in children vary over seasons and might thus influence the injury patterns. However, very little information is available on the distribution of injuries over the calendar year. This study aims to describe and analyse the seasonal variation in extremity...

  7. Seasonal variations of all-cause and cause-specific mortality by age, gender, and socioeconomic condition in urban and rural areas of Bangladesh.

    Science.gov (United States)

    Burkart, Katrin; Khan, Mobarak H; Krämer, Alexander; Breitner, Susanne; Schneider, Alexandra; Endlicher, Wilfried R

    2011-08-04

    Mortality exhibits seasonal variations, which to a certain extent can be considered as mid-to long-term influences of meteorological conditions. In addition to atmospheric effects, the seasonal pattern of mortality is shaped by non-atmospheric determinants such as environmental conditions or socioeconomic status. Understanding the influence of season and other factors is essential when seeking to implement effective public health measures. The pressures of climate change make an understanding of the interdependencies between season, climate and health especially important. This study investigated daily death counts collected within the Sample Vital Registration System (VSRS) established by the Bangladesh Bureau of Statistics (BBS). The sample was stratified by location (urban vs. rural), gender and socioeconomic status. Furthermore, seasonality was analyzed for all-cause mortality, and several cause-specific mortalities. Daily deviation from average mortality was calculated and seasonal fluctuations were elaborated using non parametric spline smoothing. A seasonality index for each year of life was calculated in order to assess the age-dependency of seasonal effects. We found distinctive seasonal variations of mortality with generally higher levels during the cold season. To some extent, a rudimentary secondary summer maximum could be observed. The degree and shape of seasonality changed with the cause of death as well as with location, gender, and SES and was strongly age-dependent. Urban areas were seen to be facing an increased summer mortality peak, particularly in terms of cardiovascular mortality. Generally, children and the elderly faced stronger seasonal effects than youths and young adults. This study clearly demonstrated the complex and dynamic nature of seasonal impacts on mortality. The modifying effect of spatial and population characteristics were highlighted. While tropical regions have been, and still are, associated with a marked excess of

  8. Seasonal variations of all-cause and cause-specific mortality by age, gender, and socioeconomic condition in urban and rural areas of Bangladesh

    Directory of Open Access Journals (Sweden)

    Burkart Katrin

    2011-08-01

    Full Text Available Abstract Background Mortality exhibits seasonal variations, which to a certain extent can be considered as mid-to long-term influences of meteorological conditions. In addition to atmospheric effects, the seasonal pattern of mortality is shaped by non-atmospheric determinants such as environmental conditions or socioeconomic status. Understanding the influence of season and other factors is essential when seeking to implement effective public health measures. The pressures of climate change make an understanding of the interdependencies between season, climate and health especially important. Methods This study investigated daily death counts collected within the Sample Vital Registration System (VSRS established by the Bangladesh Bureau of Statistics (BBS. The sample was stratified by location (urban vs. rural, gender and socioeconomic status. Furthermore, seasonality was analyzed for all-cause mortality, and several cause-specific mortalities. Daily deviation from average mortality was calculated and seasonal fluctuations were elaborated using non parametric spline smoothing. A seasonality index for each year of life was calculated in order to assess the age-dependency of seasonal effects. Results We found distinctive seasonal variations of mortality with generally higher levels during the cold season. To some extent, a rudimentary secondary summer maximum could be observed. The degree and shape of seasonality changed with the cause of death as well as with location, gender, and SES and was strongly age-dependent. Urban areas were seen to be facing an increased summer mortality peak, particularly in terms of cardiovascular mortality. Generally, children and the elderly faced stronger seasonal effects than youths and young adults. Conclusion This study clearly demonstrated the complex and dynamic nature of seasonal impacts on mortality. The modifying effect of spatial and population characteristics were highlighted. While tropical regions have

  9. Sedimentary oxygen dynamics in a seasonally hypoxic basin

    NARCIS (Netherlands)

    Seitaj, D.; Sulu-Gambari, F; Burdorf, L.D.W.; Romero-Ramirez, A.; Maire, O.; Malkin, S.Y.; Slomp, C. P.; Meysman, F.J.R.

    2017-01-01

    Seasonal hypoxia refers to the oxygen depletion that occurs in summer in the bottom water of stratifiedsystems, and is increasingly observed in coastal areas worldwide. The process induces a seasonal cycle on thebiogeochemistry of the underlying sediments, which remains poorly quantified. Here, we

  10. Sedimentary oxygen dynamics in a seasonally hypoxic basin

    NARCIS (Netherlands)

    Seitaj, D.; Sulu-Gambari, F; Burdorf, L.D.W.; Romero-Ramirez, A.; Maire, O.; Malkin, S.Y.; Slomp, C. P.; Meysman, F.J.R.

    2017-01-01

    Seasonal hypoxia refers to the oxygen depletion that occurs in summer in the bottom water of stratifiedsystems, and is increasingly observed in coastal areas worldwide. The process induces a seasonal cycle on thebiogeochemistry of the underlying sediments, which remains poorly quantified. Here, we i

  11. Seasonal Variations in Surface Metabolite Composition of Fucus vesiculosus and Fucus serratus from the Baltic Sea

    Science.gov (United States)

    Rickert, Esther; Wahl, Martin; Link, Heike; Richter, Hannes; Pohnert, Georg

    2016-01-01

    Perennial macroalgae within the genus Fucus are known to exude metabolites through their outer thallus surface. Some of these metabolites have pro- and/or antifouling properties. Seasonal fluctuations of natural fouling pressure and chemical fouling control strength against micro- and macrofoulers have previously been observed in Fucus, suggesting that control strength varies with threat. To date, a study on the seasonal composition of surface associated metabolites, responsible for much of the fouling control, has not been done. We sampled individuals of the two co-occurring species F. vesiculosus and F. serratus at monthly intervals (six per species and month) during a one-year field study. We analysed the chemical composition of surface associated metabolites of both Fucus species by means of gas chromatography-mass spectrometry (GC-MS) to describe temporal patterns in chemical surface composition. Additionally, we correlated abiotic and biotic parameters recorded monthly within the sampled habitat with the variation in the chemical surface landscape of Fucus. Our study revealed that the chemical surface composition of both Fucus species exhibits substantial seasonal differences between spring/summer and autumn/winter months. Light and temperature explained most of the seasonal variability in surface metabolite composition of both Fucus species. A strong summerly up-regulation of eighteen saccharides and two hydroxy acids in F. vesiculosus as well as of four fatty acids and two saccharides in F. serratus was observed. We discuss how these up-regulated molecules may have a complex effect on associated microfoulers, both promoting or decreasing fouling depending on metabolite and bacterial identity. These seasonal shifts in the surface metabolome seem to exert a compound control of density and composition of the Fucus associated biofilm. PMID:27959901

  12. Seasonal variations in TSH serum levels in athyreotic patients under L-thyroxine replacement monotherapy.

    Science.gov (United States)

    Gullo, Damiano; Latina, Adele; Frasca, Francesco; Squatrito, Sebastiano; Belfiore, Antonino; Vigneri, Riccardo

    2017-08-01

    Whether serum TSH undergoes seasonal fluctuations in euthyroid and hypothyroid residents of temperate climates is controversial. Monthly TSH and thyroid hormone levels were cross-sectionally analysed in a large cohort of euthyroid subjects (n=11 806) and L-thyroxine (L-T4)-treated athyreotic patients (n=3 934). Moreover, in a small group (n=119) of athyreotic patients treated with an unchanged dosage of L-T4 monotherapy, hormones were measured both in the coldest and in the hottest seasons of the same year (longitudinal study). No seasonal hormone change was observed in the euthyroid subjects except for a small FT3 increase in winter (+2.9%, PL-T4-treated athyreotic patients had significantly higher serum TSH values in the cold season when the FT4 values were significantly lower. The differences were more notable in the longitudinal series (TSH, 0.80 vs. 0.20 mU/L and FT4, 16.3 vs. 17.8 pmol/L in December-March vs. June-September, respectively). In these patients also serum FT3 values significantly decreased in winter (in the longitudinal series, 3.80 in winter vs 4.07 pmol/L in summer). Regression analysis showed that in athyreotic subjects, a greater FT4 change is required to obtain a TSH change similar to that of euthyroid controls and that this effect is more pronounced in the summer. Athyreotic patients undergoing L-T4 monotherapy have abnormal seasonal variations in TSH. These changes are secondary to the FT4 and FT3 serum decreases in winter, which occur in spite of the constant treatment. The underlying mechanisms are unclear, but in some cases, these changes may be clinically relevant. © 2017 John Wiley & Sons Ltd.

  13. Seasonal Variations in Surface Metabolite Composition of Fucus vesiculosus and Fucus serratus from the Baltic Sea.

    Science.gov (United States)

    Rickert, Esther; Wahl, Martin; Link, Heike; Richter, Hannes; Pohnert, Georg

    2016-01-01

    Perennial macroalgae within the genus Fucus are known to exude metabolites through their outer thallus surface. Some of these metabolites have pro- and/or antifouling properties. Seasonal fluctuations of natural fouling pressure and chemical fouling control strength against micro- and macrofoulers have previously been observed in Fucus, suggesting that control strength varies with threat. To date, a study on the seasonal composition of surface associated metabolites, responsible for much of the fouling control, has not been done. We sampled individuals of the two co-occurring species F. vesiculosus and F. serratus at monthly intervals (six per species and month) during a one-year field study. We analysed the chemical composition of surface associated metabolites of both Fucus species by means of gas chromatography-mass spectrometry (GC-MS) to describe temporal patterns in chemical surface composition. Additionally, we correlated abiotic and biotic parameters recorded monthly within the sampled habitat with the variation in the chemical surface landscape of Fucus. Our study revealed that the chemical surface composition of both Fucus species exhibits substantial seasonal differences between spring/summer and autumn/winter months. Light and temperature explained most of the seasonal variability in surface metabolite composition of both Fucus species. A strong summerly up-regulation of eighteen saccharides and two hydroxy acids in F. vesiculosus as well as of four fatty acids and two saccharides in F. serratus was observed. We discuss how these up-regulated molecules may have a complex effect on associated microfoulers, both promoting or decreasing fouling depending on metabolite and bacterial identity. These seasonal shifts in the surface metabolome seem to exert a compound control of density and composition of the Fucus associated biofilm.

  14. Annual and seasonal variations in the low-latitude topside ionosphere

    Directory of Open Access Journals (Sweden)

    Y. Z. Su

    Full Text Available Annual and seasonal variations in the low-latitude topside ionosphere are investigated using observations made by the Hinotori satellite and the Sheffield University Plasmasphere Ionosphere Model (SUPIM. The observed electron densities at 600 km altitude show a strong annual anomaly at all longitudes. The average electron densities of conjugate latitudes within the latitude range ±25° are higher at the December solstice than at the June solstice by about 100 during daytime and 30 during night-time. Model calculations show that the annual variations in the neutral gas densities play important roles. The model values obtained from calculations with inputs for the neutral densities obtained from MSIS86 reproduce the general behaviour of the observed annual anomaly. However, the differences in the modelled electron densities at the two solstices are only about 30 of that seen in the observed values. The model calculations suggest that while the differences between the solstice values of neutral wind, resulting from the coupling of the neutral gas and plasma, may also make a significant contribution to the daytime annual anomaly, the E×B drift velocity may slightly weaken the annual anomaly during daytime and strengthen the anomaly during the post-sunset period. It is suggested that energy sources, other than those arising from the 6 difference in the solar EUV fluxes at the two solstices due to the change in the Sun-Earth distance, may contribute to the annual anomaly. Observations show strong seasonal variations at the solstices, with the electron density at 600 km altitude being higher in the summer hemisphere than in the winter hemisphere, contrary to the behaviour in NmF2. Model calculations confirm that the seasonal behaviour results from effects caused by transequatorial component of the neutral wind in the direction summer hemisphere to winter hemisphere.

  15. Study of Seasonal Variation in Groundwater Quality of Sagar City (India by Principal Component Analysis

    Directory of Open Access Journals (Sweden)

    Hemant Pathak

    2011-01-01

    Full Text Available Groundwater is one of the major resources of the drinking water in Sagar city (India.. In this study 15 sampling station were selected for the investigations on 14 chemical parameters. The work was carried out during different months of the pre-monsoon, monsoon and post-monsoon seasons in June 2009 to June 2010. The multivariate statistics such as principal component and cluster analysis were applied to the datasets to investigate seasonal variations in groundwater quality. Principal axis factoring has been used to observe the mode of association of parameters and their interrelationships, for evaluating water quality. Average value of BOD, COD, ammonia and iron was high during entire study period. Elevated values of BOD and ammonia in monsoon, slightly more value of BOD in post-monsoon, BOD, ammonia and iron in pre-monsoon period reflected contribution on temporal effect on groundwater. Results of principal component analysis evinced that all the parameters equally and significantly contribute to groundwater quality variations. Factor 1 and factor 2 analysis revealed the DO value deteriorate due to organic load (BOD/Ammonia in different seasons. Hierarchical cluster analysis grouped 15 stations into four clusters in monsoon, five clusters in post-monsoon and five clusters in pre-monsoon with similar water quality features. Clustered group at monsoon, post-monsoon and pre-monsoon consisted one station exhibiting significant spatial variation in physicochemical composition. The anthropogenic nitrogenous species, as fallout from modernization activities. The study indicated that the groundwater sufficiently well oxygenated and nutrient-rich in study places.

  16. Seasonal variation in nutritional characteristics of the diet of greater white-fronted geese

    Science.gov (United States)

    Ely, Craig R.; Raveling, Dennis G.

    2011-01-01

    We studied diet and habitat use of greater white-fronted geese (Anser albifrons) from autumn through spring on their primary staging and wintering areas in the Pacific Flyway, 1979-1982. There have been few previous studies of resource use and forage quality of wintering greater white-fronted geese in North America, and as a consequence there has been little empirical support for management practices pertaining to habitat conservation of this broadly distributed species. Observations of >2,500 flocks of geese and collections of foraging birds revealed seasonal and geographic variation in resource use reflective of changes in habitat availability, selection, and fluctuating physiological demands. Autumn migrants from Alaska arrived first in the Klamath Basin of California and southern Oregon, where they fed on barley, oats, wheat, and potatoes. Geese migrated from the Klamath Basin into the Central Valley of California in late autumn where they exploited agricultural crops rich in soluble carbohydrates, with geese in the Sacramento Valley feeding almost exclusively on rice and birds on the Sacramento-San Joaquin Delta primarily utilizing corn. White-fronted geese began their northward migration in late winter, and by early spring most had returned to the Klamath Basin where 37% of flocks were found in fields of new growth cultivated and wild grasses. Cereal grains and potatoes ingested by geese were low in protein (7-14%) and high in soluble nutrients (17-47% neutral detergent fiber [NDF]), whereas grasses were low in available energy (47-49% NDF) but high in protein (26-42%). Greater white-fronted geese are generalist herbivores and can exploit a variety of carbohydrate-rich cultivated crops, likely making these geese less susceptible to winter food shortages than prior to the agriculturalization of the North American landscape. However, agricultural landscapes can be extremely dynamic and may be less predictable in the long-term than the historic environments to

  17. Seasonal variations of bisphenol A in the Danube River by the municipality of Novi Sad, Serbia

    Directory of Open Access Journals (Sweden)

    Milanović Maja

    2016-01-01

    Full Text Available Seasonal variations of bisphenol A (BPA were investigated in the Danube along the Novi Sad bank, Serbia using solid-phase extraction followed by gas chromatographic mass spectrometric method. The obtained results confirmed the presence of BPA above the limit of quantification (6 ng/L in 22 out of 32 water samples at all eight sampling sites. Тhe BPA concentration varied from 1 for autumn, spring and summer. The high potential risk which is attributed to the elevated summer concentrations is probably the result of the increased human activates and weather conditions. [Projekat Ministarstva nauke Republike Srbije, br. III46009

  18. Seasonal Changes in Atmospheric Noise Levels and the Annual Variation in Pigeon Homing Performance

    Science.gov (United States)

    Hagstrum, J. T.; McIsaac, H. P.; Drob, D. P.

    2015-12-01

    The remarkable navigational ability of homing pigeons (Columba livia) is influenced by a number of factors, an unknown one of which causes the "Wintereffekt"1 or annual variation in homing performance. Minima in homeward orientation and return speeds have been observed in winter, with maxima in summer, during repetitive pigeon releases from single sites near experimental lofts in Wilhelmshaven, Göttingen, and Munich, Germany, and near Pisa, Italy1-4. Overall the annual variation is more pronounced in northern Germany than Italy4, and both mature and juvenile cohorts respond to this seasonal factor. Older, more experienced pigeons are better at compensating for its effects than naïve ones, but are still affected after numerous releases. The narrow low-frequency band of atmospheric background noise (microbaroms; 0.1-0.3 Hz) also varies with an annual cycle that generally has higher amplitudes in winter than in summer depending on location5. In addition, homing pigeons, and possibly other birds, apparently use infrasonic signals of similar frequency as navigational cues6, and a seasonal variation in background noise levels could cause corresponding changes in signal-to-noise ratios and thus in homing performance. The annual variation in homing performance, however, was not observed during long-term pigeon releases at two sites in eastern North America. The annual and geographic variability in homing performance in the northern hemisphere can be explained to a first order by seasonal changes in infrasonic noise sources related to ocean storm activity, and to the direction and intensity of stratospheric winds. In addition, increased dispersion in departure bearings of individual birds for some North American releases were likely caused by additional infrasonic noise associated with severe weather events during tornado and Atlantic hurricane seasons. 1Kramer, G. & von Saint Paul, U., J. Ornithol. 97, 353-370 (1956); 2Wallraff, H. G., Z. Tierpsychol. 17, 82-113 (1960

  19. Mariner 9 ultraviolet spectrometer experiment: Seasonal variation of ozone on Mars

    Science.gov (United States)

    Barth, C. A.; Hord, C. W.; Stewart, A. I.; Lane, A. L.; Dick, M. L.; Anderson, G. P.

    1973-01-01

    On Mars, the Mariner observations show a twenty-fold variation in the amount of ozone, depending on the presence or absence of another minor constituent, water vapor, in the atmosphere. In the evolution of earth's primitive atmosphere, the formation of an ozone layer may have played an important role in the prebiotic chemistry that took place on the surface. The seasonal formation and disappearance of ozone in the contemporary Martian atmosphere may be of consequence in any prebiotic chemistry that may be occurring there.

  20. Seasonal Dynamics of Phlebotomine Sand Fly Species Proven Vectors of Mediterranean Leishmaniasis Caused by Leishmania infantum.

    Directory of Open Access Journals (Sweden)

    Bulent Alten

    2016-02-01

    Full Text Available The recent geographical expansion of phlebotomine vectors of Leishmania infantum in the Mediterranean subregion has been attributed to ongoing climate changes. At these latitudes, the activity of sand flies is typically seasonal; because seasonal phenomena are also sensitive to general variations in climate, current phenological data sets can provide a baseline for continuing investigations on sand fly population dynamics that may impact on future scenarios of leishmaniasis transmission. With this aim, in 2011-2013 a consortium of partners from eight Mediterranean countries carried out entomological investigations in sites where L. infantum transmission was recently reported.A common protocol for sand fly collection included monthly captures by CDC light traps, complemented by sticky traps in most of the sites. Collections were replicated for more than one season in order to reduce the effects of local weather events. In each site, the trapping effort was left unchanged throughout the survey to legitimate inter-seasonal comparisons. Data from 99,000 collected specimens were analyzed, resulting in the description of seasonal dynamics of 56,000 sand flies belonging to L. infantum vector species throughout a wide geographical area, namely P. perniciosus (Portugal, Spain and Italy, P. ariasi (France, P. neglectus (Greece, P. tobbi (Cyprus and Turkey, P. balcanicus and P. kandelakii (Georgia. Time of sand fly appearance/disappearance in collections differed between sites, and seasonal densities showed variations in each site. Significant correlations were found between latitude/mean annual temperature of sites and i the first month of sand fly appearance, that ranged from early April to the first half of June; ii the type of density trend, varying from a single peak in July/August to multiple peaks increasing in magnitude from May through September. A 3-modal trend, recorded for P. tobbi in Cyprus, represents a novel finding for a L. infantum vector

  1. Seasonal Dynamics of Phlebotomine Sand Fly Species Proven Vectors of Mediterranean Leishmaniasis Caused by Leishmania infantum

    Science.gov (United States)

    Alten, Bulent; Maia, Carla; Afonso, Maria Odete; Campino, Lenea; Jiménez, Maribel; González, Estela; Molina, Ricardo; Bañuls, Anne Laure; Prudhomme, Jorian; Vergnes, Baptiste; Toty, Celine; Cassan, Cécile; Rahola, Nil; Thierry, Magali; Sereno, Denis; Bongiorno, Gioia; Bianchi, Riccardo; Khoury, Cristina; Tsirigotakis, Nikolaos; Dokianakis, Emmanouil; Antoniou, Maria; Christodoulou, Vasiliki; Mazeris, Apostolos; Karakus, Mehmet; Ozbel, Yusuf; Arserim, Suha K.; Erisoz Kasap, Ozge; Gunay, Filiz; Oguz, Gizem; Kaynas, Sinan; Tsertsvadze, Nikoloz; Tskhvaradze, Lamzira; Gramiccia, Marina; Volf, Petr; Gradoni, Luigi

    2016-01-01

    Background The recent geographical expansion of phlebotomine vectors of Leishmania infantum in the Mediterranean subregion has been attributed to ongoing climate changes. At these latitudes, the activity of sand flies is typically seasonal; because seasonal phenomena are also sensitive to general variations in climate, current phenological data sets can provide a baseline for continuing investigations on sand fly population dynamics that may impact on future scenarios of leishmaniasis transmission. With this aim, in 2011–2013 a consortium of partners from eight Mediterranean countries carried out entomological investigations in sites where L. infantum transmission was recently reported. Methods/Principal Findings A common protocol for sand fly collection included monthly captures by CDC light traps, complemented by sticky traps in most of the sites. Collections were replicated for more than one season in order to reduce the effects of local weather events. In each site, the trapping effort was left unchanged throughout the survey to legitimate inter-seasonal comparisons. Data from 99,000 collected specimens were analyzed, resulting in the description of seasonal dynamics of 56,000 sand flies belonging to L. infantum vector species throughout a wide geographical area, namely P. perniciosus (Portugal, Spain and Italy), P. ariasi (France), P. neglectus (Greece), P. tobbi (Cyprus and Turkey), P. balcanicus and P. kandelakii (Georgia). Time of sand fly appearance/disappearance in collections differed between sites, and seasonal densities showed variations in each site. Significant correlations were found between latitude/mean annual temperature of sites and i) the first month of sand fly appearance, that ranged from early April to the first half of June; ii) the type of density trend, varying from a single peak in July/August to multiple peaks increasing in magnitude from May through September. A 3-modal trend, recorded for P. tobbi in Cyprus, represents a novel

  2. Seasonal variations of melatonin in ram seminal plasma are correlated to those of testosterone and antioxidant enzymes

    Directory of Open Access Journals (Sweden)

    Muiño-Blanco Teresa

    2010-06-01

    Full Text Available Abstract Background Some breeds of sheep are highly seasonal in terms of reproductive capability, and these changes are regulated by photoperiod and melatonin secretion. These changes affect the reproductive performance of rams, impairing semen quality and modifying hormonal profiles. Also, the antioxidant defence systems seem to be modulated by melatonin secretion, and shows seasonal variations. The aim of this study was to investigate the presence of melatonin and testosterone in ram seminal plasma and their variations between the breeding and non-breeding seasons. In addition, we analyzed the possible correlations between these hormones and the antioxidant enzyme defence system activity. Methods Seminal plasma from nine Rasa Aragonesa rams were collected for one year, and their levels of melatonin, testosterone, superoxide dismutase (SOD, glutathione reductase (GRD, glutathione peroxidase (GPX and catalase (CAT were measured. Results All samples presented measurable quantities of hormones and antioxidant enzymes. Both hormones showed monthly variations, with a decrease after the winter solstice and a rise after the summer solstice that reached the maximum levels in October-November, and a marked seasonal variation (P Conclusions These results show the presence of melatonin and testosterone in ram seminal plasma, and that both hormones have seasonal variations, and support the idea that seasonal variations of fertility in the ram involve interplay between melatonin and the antioxidant defence system.

  3. Characterization of surface and ground water δ18O seasonal variation and its use for estimating groundwater residence times

    Science.gov (United States)

    Reddy, Michael M.; Schuster, Paul; Kendall, Carol; Reddy, Micaela B.

    2006-01-01

    18O is an ideal tracer for characterizing hydrological processes because it can be reliably measured in several watershed hydrological compartments. Here, we present multiyear isotopic data, i.e. 18O variations (δ18O), for precipitation inputs, surface water and groundwater in the Shingobee River Headwaters Area (SRHA), a well-instrumented research catchment in north-central Minnesota. SRHA surface waters exhibit δ18O seasonal variations similar to those of groundwaters, and seasonal δ18O variations plotted versus time fit seasonal sine functions. These seasonal δ18O variations were interpreted to estimate surface water and groundwater mean residence times (MRTs) at sampling locations near topographically closed-basin lakes. MRT variations of about 1 to 16 years have been estimated over an area covering about 9 km2 from the basin boundary to the most downgradient well. Estimated MRT error (±0·3 to ±0·7 years) is small for short MRTs and is much larger (±10 years) for a well with an MRT (16 years) near the limit of the method. Groundwater transit time estimates based on Darcy's law, tritium content, and the seasonal δ18O amplitude approach appear to be consistent within the limits of each method. The results from this study suggest that use of the δ18O seasonal variation method to determine MRTs can help assess groundwater recharge areas in small headwaters catchments.

  4. [Seasonal dynamics of quantitative and morphological traits of poplar fine roots and their differences between successive rotation plantations].

    Science.gov (United States)

    Wang, Yan-ping; Xu, Tan; Zhu, Wan-rui; Wang, Qi-tong; Liu, Meng-ling; Wang, Hua-tian; Li, Chuan-rong; Dong, Yu-feng

    2016-02-01

    Based on the fine root samples of the first and second generations of poplar (Populus x euramericana ' Neva'), this study examined the response of quantitative and morphological traits of fine roots of different orders and the difference between generations. The results showed that, the quantitative traits of fine roots, such as root length, root surface area and root biomass, presented obvious seasonal variation, and the fine root traits had obvious difference among root orders. The quantitative traits of lower-order fine roots showed significant seasonal difference, and the fine root biomass increased in the growing season and then decreased significantly. The specific root length (SRL) of higher-order roots also showed significant change with season, while the root length density (RLD) and root tissue density (RTD) changed a little. The successive rotation resulted in the significant increase of root length, root biomass, SRL and RLD of 1-2 orders in the growing season. The quantitative traits of first order root significantly positively correlated with soil temperature and moisture, and significantly negatively correlated with the soil organic matter and soil available nitrogen content. However, the quantitative traits of second order root only showed significant correlation with soil nutrient content. The seasonal dynamics of poplar fine roots and the difference between successive rotation plantations implied carbon investment change of poplar to roots. Soil nutrient deficiency induced more carbon investment into roots, and this carbon allocation pattern might affect the aboveground productivity of poplar plantation.

  5. The dynamical and microphysical properties of wet season convection in Darwin as a function of wet season regime.

    Science.gov (United States)

    Jackson, Robert; Collis, Scott; Protat, Alain; Majewski, Leon; Louf, Valentin; Potvin, Corey; Lang, Timothy

    2017-04-01

    A known deficiency of general circulation models (GCMs) is in their representation of convection (Arakawa 2004), typically parameterized using given assumptions about entrainment rates and mass fluxes that depend on the dynamical and microphysical characteristics of convection and lack any sort of representation of the organization of convection. Furthermore, mechanisms that couple large scale forcing and convective organization are poorly represented (Del Genio 2012). The Accelerated Climate Model for Energy (ACME) version 1 aims to run at resolutions of 25 km, too coarse for convective parameterizations used in large eddy simulations but too fine for typical convective parameterizations used in GCMs. This prompts the need for observational datasets to validate simulations and guide model development in ACME in several regions of the globe. The focus of this study will be at the Tropical Western Pacific (TWP) site in Darwin, Australia and the surrounding maritime continent. In Darwin, well defined forcing regimes occur during the wet season of September to April with the onset and the break of the Northern Australian Monsoon (Drosdowsky 1996; Pope et al. 2009). In this study, the vertical velocities retrieved from over ten years of continuous plan position indicator scans from the C-band POLarimetric and Berrima radars stationed at the Atmospheric Radiation Measurement TWP site in Darwin are derived. This long term dataset in such a region provides an opportunity to explore the statistics of vertical velocities in convection as a function of large scale forcing and modes of convective organization. Initial attempts to classify the convective organizational state and derive vertical velocities using three-dimensional variational data retrieval (Potvin et al. 2012) are shown. The results will be used to validate ACME Regionally Refined Mesh simulations over Darwin as well as guide convective parameterization development.

  6. Seasonal Variations of Mid-Latitude Ionospheric Trough Structure Observed with DEMETER and COSMIC

    Directory of Open Access Journals (Sweden)

    Matyjasiak Barbara

    2016-12-01

    Full Text Available The mid-latitude ionospheric trough is a depleted region of ionospheric plasma observed in the topside ionosphere. Its behavior can provide useful information about the magnetospheric dynamics, since its existence is sensitive to magnetospherically induced motions. Mid-latitude trough is mainly a night-time phenomenon. Both, its general features and detailed characteristics strongly depend on the level of geomagnetic disturbances, time of the day, season, and the solar cycle, among others. Although many studies provide basic information about general characteristics of the main ionospheric trough structure, an accurate prediction of the trough behavior in specific events is still understood poorly. The paper presents the mid-latitude trough characteristics with regard to the geomagnetic longitude and season during a solar activity minimum, as based on the DEMETER in situ satellite measurements and the data retrieved from FORMOSAT-3/COSMIC radio occultation measurements.

  7. Seasonal variation measurements of radon levels in caves using SSNTD method

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa, G. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, 01000 Mexico, D.F. (Mexico)], E-mail: espinosa@fisica.unam.mx; Golzarri, J.I. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, 01000 Mexico, D.F. (Mexico); Gammage, R.B. [Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831-6480 (United States); Sajo-Bohus, L. [Departamento de Fisica, Universidad Simon Bolivar (Venezuela); Viccon-Pale, J.; Signoret-Poillon, M. [El Hombre y su Ambiente, UAM-Xochimilco, Mexico D.F. (Mexico)

    2008-08-15

    The results of radon concentration measurements inside of the Gabriel caves of Mexico, during three consecutive two-month periods covering almost three seasons, are reported in the present work. The radio-ecological importance of this site is related to the radon and its concentration-dynamic behavior in the cave. Further interest in radiation safety motivated this initiative since routine biological field work is done, with people spending long periods of time there. CR-39 passive nuclear track detector was chosen for this survey. Radon concentration levels decrease during the rainy season and show different values depending on the ventilation and geometeorological structure. Measured values range between 956 and 4931Bqm{sup -3}, an indication that radon doses may exceed the allowed values for workers. This project is part of a larger study of indoor radon alpha emitters in Mexican caves.

  8. Seasonal and Non-Seasonal Variations of Jupiter's Atmosphere from Observations of Thermal Emission, 1994-2011

    Science.gov (United States)

    Orton, G.; Fletcher, L.; Yanamandra-Fisher, P.; Greathouse, T.; Fisher, B.; Greco, J.; Wakefield, L.; Snead, E.; Boydstun, K.; Simon-Miller, A.; Arzumanyan, G.; Christian, J.

    2012-01-01

    We analyzed mid-infrared images of Jupiter's thermal emission, covering approx.1.5 Jovian years, acquired in discrete filters between 7.8 and 24.5 microns. The behavior of stratospheric (approx.10-mbar) and tropospheric (approx.100-400 mbar) temperatures is generally consistent with predictions of seasonal variability, with differences between 100-mbar temperatures +/-50-60deg from the equator on the order of +/-2. Removing this effect, there appear to be long-term quasi-periodic variability of tropospheric temperatures, whose amplitude, phase and period depend on latitude. The behavior of temperatures in the Equatorial Zone (EZ) suggests a approx.4-6-year period with amplitude of about +/-1-1.5 K in temperature. At mid-latitudes, the periodicity is more distinct with amplitudes around +/-1.5-2.5 K and 4-8 year periods. The 4.2-year variation of stratospheric temperatures known as the quasiquadrennial oscillation or "QQO" (Leovy et al. 1991, Nature 354, 380) continued during this period. There were no variations of zonal mean temperatures associated with any of the "global upheaval" events that have produced dramatic changes of jupiter's visible appearance and cloud cover, although there are colder discrete regions associated with updrafts, e.g. the early stages of the re-darkening ("revival") of the South Equatorial Belt (SEB) in late 2010. On the other hand increases in the visible albedos ("fades") of belts are accompanied by increases in the thickness of a 700-mbar cloud layer (most likely NH3 ice) and clouds at higher pressures, together with the mixing ratio of NH3 gas near 400 mbar (above its condensation level). These quantities decrease during re-darkening ("revival") episodes, during which we note discrete features that are exceptions to the general correlation between dark albedos and minimal cloudiness. In contrast to all these changes, the meridional distribution of the 240-mbar para-H2 fraction appears to be invariant in time.

  9. Effects of drought season length on live moisture content dynamic in Mediterranean shrubs: 8 years of data

    Science.gov (United States)

    Pellizzaro, Grazia; Ventura, Andrea; Bortolu, Sara; Duce, Pierpaolo

    2017-04-01

    Mediterranean shrubs are an important component of Mediterranean vegetation communities. In this kind of vegetation, live fuel is a relevant component of the available fuel which catches fire and, consequently, its water content plays an important role in determining fire occurrence and spread. In live plant, water content patterns are related to both environmental conditions (e.g. meteorological variables, soil water availability) and ecophysiological characteristics of the plant species. According to projections on future climate, an increase in risk of summer droughts is likely to take place in Southern Europe. More prolonged drought seasons induced by climatic changes are likely to influence general flammability characteristics of fuel. In addition, variations in precipitation and mean temperature could directly affect fuel water status and length of critical periods of high ignition danger for Mediterranean ecosystems. The aims of this work were to analyse the influence of both weather seasonality and inter-annual weather variability on live fuel moisture content within and among some common Mediterranean species, and to investigate the effects of prolonged drought season on live moisture content dynamic. The study was carried out in North Sardinia (Italy). Measurements of LFMC seasonal pattern of two really common and flammable Mediterranean shrub species (Cistus monspeliensis and Rosmarinus officinalis) were performed periodically for 8 years. Meteorological variables were also recorded. Relationships between live fuel moisture content and environmental conditions (i.e. rainfall, air temperature and soil moisture) were investigated and effects of different lengths of drought season on LFMC pattern were analysed. Results showed that distribution and amount of rainfall affected seasonal variation of live fuel moisture content. In particular more prolonged drought seasons caused a longer period in which LFMC was below 95 -100% that is commonly considered as

  10. Evaluating seasonal dynamics of bacterial communities in marine fish aquaculture: a preliminary study before applying phage therapy.

    Science.gov (United States)

    Pereira, Carla; Salvador, Sara; Arrojado, Cátia; Silva, Yolanda; Santos, Ana L; Cunha, Angela; Gomes, Newton C M; Gomes, Newton; Almeida, Adelaide

    2011-04-01

    The increasing problem of antibiotic resistance in common pathogenic bacteria and the concern about the spreading of antibiotics in the environment bring the need to find new methods to control fish pathogens. Phage therapy represents a potential alternative to antibiotics, but its use in aquaculture requires a detailed understanding of bacterial communities, namely of fish pathogenic bacteria. Therefore, in this study the seasonal dynamics of the overall bacterial communities, microbiological water quality and disease-causing bacteria were followed in a marine aquaculture system of Ria de Aveiro (Portugal). Analysis of the bacterial diversity of the water samples by denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments indicates that the bacterial community structure varied seasonally, showing a higher complexity during the warm season. The diversity of the main fish pathogenic bacteria, assessed by DGGE targeting the Vibrio genus, showed lower seasonal variation, with new dominating populations appearing mainly in the spring. Bacterial indicators, faecal coliforms and enterococci, enumerated by the filter-membrane method, also varied seasonally. The fluorescent in situ hybridization (FISH) results showed that the specific groups of bacteria varied during the study period and that the non-indigenous Enterobactereaceae family was the most abundant group followed by Vibrio and Aeromonas. The seasonal variation detected in terms of density and structure of total and pathogenic bacterial communities demonstrates the need for a careful monitoring of water through the year in order to select the suitable phages to inactivate fish pathogenic bacteria. The spring season seems to be the critical time period when phage therapy should be applied.

  11. Estimating seasonal variations in cloud droplet number concentration over the boreal forest from satellite observations

    Directory of Open Access Journals (Sweden)

    R. H. H. Janssen

    2011-08-01

    Full Text Available Seasonal variations in cloud droplet number concentration (NCD in low-level stratiform clouds over the boreal forest are estimated from MODIS observations of cloud optical and microphysical properties, using a sub-adiabatic cloud model to interpret vertical profiles of cloud properties. An uncertainty analysis of the cloud model is included to reveal the main sensitivities of the cloud model. We compared the seasonal cycle in NCD, obtained using 9 yr of satellite data, to surface concentrations of potential cloud activating aerosols, measured at the SMEAR II station at Hyytiälä in Finland. The results show that NCD and cloud condensation nuclei (CCN concentrations have no clear correlation at seasonal time scale. The fraction of aerosols that actually activate as cloud droplet decreases sharply with increasing aerosol concentrations. Furthermore, information on the stability of the atmosphere shows that low NCD is linked to stable atmospheric conditions. Combining these findings leads to the conclusion that cloud droplet activation for the studied clouds over the boreal forest is limited by convection. Our results suggest that it is important to take the strength of convection into account when studying the influence of aerosols from the boreal forest on cloud formation, although they do not rule out the possibility that aerosols from the boreal forest affect other types of clouds with a closer coupling to the surface.

  12. Simulations of seasonal variations of stable water isotopes in land surface process model CLM

    Institute of Scientific and Technical Information of China (English)

    ZHANG XinPing; WANG XiaoYun; YANG ZongLiang; NIU GuoYue; Xie ZiChu

    2009-01-01

    In this study, we simulated and analyzed the monthly variations of stable water isotopes in different reservoirs at Manaus, Brazil, using the Community Land Model (CLM) that incorporates stable isotopic effects as a diagnostic tool for understanding stable water isotopic processes, filling the observational data gaps and predicting hydrometeorological processes. The simulation results show that the δO values in precipitation, vapor and surface runoff have distinct seasonality with the marked negative correlations with corresponding water amount. Compared with the survey results by the International Atomic Energy Agency (IAEA) in co-operation with the World Meteorological Organization (WMO), the simulations by CLM reveal the similar temporal distributions of the δO in precipitation. Moreover, the simulated amount effect between monthly δO and monthly precipitation amount, and MWL (meteoric water line) are all close to the measured values. However, the simulated seasonal difference in the δO in precipitation is distinctly smaller than observed one, and the simulated temporal distribution of the 8180 in precipitation displays the ideal bimodal seasonality rather than the observed single one. These mismatches are possibly related to the simulation capacity and the veracity in forcing data.

  13. Seasonal and spatial variations of atmospheric trace elemental deposition in the Aliaga industrial region, Turkey

    Science.gov (United States)

    Kara, Melik; Dumanoglu, Yetkin; Altiok, Hasan; Elbir, Tolga; Odabasi, Mustafa; Bayram, Abdurrahman

    2014-11-01

    Atmospheric bulk deposition (wet + dry deposition) samples (n = 40) were collected concurrently at ten sites in four seasons between June 2009 and April 2010 in the Aliaga heavily industrialized region, Turkey, containing a number of significant air pollutant sources. Analyses of trace elements were carried out using inductively coupled plasma-mass spectrometry (ICP-MS). While there were significant differences in the particulate matter (PM) deposition fluxes among the sampling sites, seasonal variations were not statistically significant (Kruskal-Wallis test, p deposition and elemental fluxes were increased at the sampling sites in the vicinity of industrial activities. The crustal elements (i.e., Ca, Mg) and some anthropogenic elements (such as Fe, Zn, Mn, Pb, Cu, and Cr) were high, and the highest fluxes were mostly measured in summer and winter seasons. The enrichment factor (EF) and principal component analysis (PCA) was applied to the data to determine the possible sources in the study area. High EF values were obtained for the anthropogenic elements such as Ag, Cd, Zn, Pb, Cu and Sb. The possible sources were identified as anthropogenic sources (i.e., iron-steel production) (45.4%), crustal and re-suspended dust (27.1%), marine aerosol (7.9%), and coal and wood combustion (8.2%). Thus, the iron-steel production and its related activities were found to be the main pollutant sources for this region.

  14. Variations of Salminus hilarii diet (Ostariophysi, Characidae): seasonal and ontogenetic effects.

    Science.gov (United States)

    Villares Junior, G A; Goitein, R

    2015-08-01

    This study described the variations seasonal and ontogenetic of Salminus hilarii diet. Samples were collected in the Sorocaba River, São Paulo, Brazil, one of the few rivers where individuals of the species still occur in a higher frequency. The preys consumed were analyzed by Importance Alimentary Index (AIi). To determine similarities between year seasons, the AIi data were analyzed by the Morisita-Horn index and reduced in cluster analysis, along with a statistical comparison made by one-way ANOSIM test (5%). The feeding activity was analyzed according to the stomach repletion index and compared among the year seasons using non parametric variance analysis Kruskal-Wallis test (5%). Comparison of prey consumed between immature and adult individuals was made by Spearman correlation (5%). A Pearson correlation (5%) was applied between the standard length of the fish and prey consumed, as well as between the mouth and prey heights. The analyzes of stomach contents showed that the diet of this species was exclusively piscivorous, with significant difference of prey consumption during the period, the same happening among adult and immature individuals. It was observed that these fishes use to swallow their prey whole and that significant correlations between size of predator and prey size can be observed. There is also correlation between the mouth height and the maximum prey depth. Salminus hilarii feeds on the available prey, and the species food composition and feeding activity depends on prey`s abundance, their size and morphology, as do the water temperatures.

  15. Seasonal Variation in Sea Turtle Density and Abundance in the Southeast Florida Current and Surrounding Waters.

    Science.gov (United States)

    Bovery, Caitlin M; Wyneken, Jeanette

    2015-01-01

    Assessment and management of sea turtle populations is often limited by a lack of available data pertaining to at-sea distributions at appropriate spatial and temporal resolutions. Assessing the spatial and temporal distributions of marine turtles in an open system poses both observational and analytical challenges due to the turtles' highly migratory nature. Surface counts of marine turtles in waters along the southern part of Florida's east coast were made in and adjacent to the southeast portion of the Florida Current using standard aerial surveys during 2011 and 2012 to assess their seasonal presence. This area is of particular concern for sea turtles as interest increases in offshore energy developments, specifically harnessing the power of the Florida Current. While it is understood that marine turtles use these waters, here we evaluate seasonal variation in sea turtle abundance and density over two years. Density of sea turtles observed within the study area ranged from 0.003 turtles km-2 in the winter of 2011 to 0.064 turtles km-2 in the spring of 2012. This assessment of marine turtles in the waters off southeast Florida quantifies their in-water abundance across seasons in this area to establish baselines and inform future management strategies of these protected species.

  16. Seasonal Variation in Sea Turtle Density and Abundance in the Southeast Florida Current and Surrounding Waters

    Science.gov (United States)

    Bovery, Caitlin M.; Wyneken, Jeanette

    2015-01-01

    Assessment and management of sea turtle populations is often limited by a lack of available data pertaining to at-sea distributions at appropriate spatial and temporal resolutions. Assessing the spatial and temporal distributions of marine turtles in an open system poses both observational and analytical challenges due to the turtles’ highly migratory nature. Surface counts of marine turtles in waters along the southern part of Florida’s east coast were made in and adjacent to the southeast portion of the Florida Current using standard aerial surveys during 2011 and 2012 to assess their seasonal presence. This area is of particular concern for sea turtles as interest increases in offshore energy developments, specifically harnessing the power of the Florida Current. While it is understood that marine turtles use these waters, here we evaluate seasonal variation in sea turtle abundance and density over two years. Density of sea turtles observed within the study area ranged from 0.003 turtles km-2 in the winter of 2011 to 0.064 turtles km-2 in the spring of 2012. This assessment of marine turtles in the waters off southeast Florida quantifies their in-water abundance across seasons in this area to establish baselines and inform future management strategies of these protected species. PMID:26717520

  17. Seasonal variation and analgesic properties of different parts from Curcuma zedoaria Roscoe (Zingiberaceae) grown in Brazil.

    Science.gov (United States)

    Pamplona, Christiane Regina; de Souza, Marcia Maria; Machado, Marina da Silva; Cechinel Filho, Valdir; Navarro, Dionezine; Yunes, Rosendo Augusto; Delle Monache, Franco; Niero, Rivaldo

    2006-01-01

    This work describes the seasonal variation of curcumenol (1) and dihydrocurdione (2), two active terpenoids from different parts (roots, mother rhizome and rugous rhizome) of Curcuma zedoaria grown in Brazil. The analysis was carried out by high resolution gas chromatography, using external standards for determination. The results showed that both terpenoids are present in all the parts studied. However, C. zedoaria exhibited about three times more terpenoids in the mother rhizome in autumn than in other parts and seasons studied. The antinociceptive activity of the dichloromethane extracts from different parts and collected in different seasons was studied using the acetic acid-induced abdominal constriction model in mice. The extracts obtained from mother rhizome collected in autumn and winter at doses of 10 mg/kg body weight, i.p., caused considerable antinociceptive activity inhibiting 91.1 and 93.4% of the abdominal constrictions, respectively, whereas compounds 1 and 2 caused inhibitions of 64.0 and 46.0%, respectively. These results confirm that both compounds contribute to explain the antinociceptive effect of the plant but suggest that other compounds are also acting as analgesics.

  18. Seasonal variation of Brazilian red propolis: Antibacterial activity, synergistic effect and phytochemical screening.

    Science.gov (United States)

    Regueira, M S; Tintino, Saulo Relison; da Silva, Ana Raquel Pereira; Costa, Maria do Socorro; Boligon, Aline Augusti; Matias, Edinardo F F; de Queiroz Balbino, Valdir; Menezes, Irwin R A; Melo Coutinho, Henrique Douglas

    2017-09-01

    The aim of this study was to investigate the effect of the dry and rainy season on the antibacterial activity and chemical composition of the Brazilian red propolis. The samples were collected in rainy (RP-PER) and dry (RP-PED) seasons and analyzed by HPLC-DAD. The extracts were tested alone and in association with antibiotics against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The HPLC analysis identified luteolin and quercetin as the main compounds. Seasonal variation was observed according to concentrations of the compounds. The MIC values against E. coli ranged from 128 μg/mL to 512 μg/mL (EC 06 and EC ATCC). The red propolis showed MIC values of 512 μg/mL against both strains of P. aeruginosa used in our study (PA03 and PA24) and against strains of Gram-positive bacteria S. aureus the MICs ranged from 64 μg/mL to ≥1024 μg/mL (SA10). A synergistic effect was observed when we combined the RP-PED with gentamicin against all the strains tested. When we combined the RP-PED with Imipenem, we only observed synergistic effect against P. aeruginosa. According to our synergistic activity results, the utilization of red propolis collected in the drier periods can be used as an adjuvant against multiresistant bacterial infections. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Seasonal variations in terpene emission factors of dominant species in four ecosystems in NE Spain

    Science.gov (United States)

    Llusia, Joan; Peñuelas, Josep; Guenther, Alex; Rapparini, Francesca

    2013-05-01

    We studied the daily patterns in the rates of foliar terpene emissions by four typical species from the Mediterranean region in two days of early spring and two days of summer in 4 localities of increasing biomass cover in Northern Spain. The species studied were Thymelaea tinctoria (in Monegros), Quercus coccifera (in Garraf), Quercus ilex (in Prades) and Fagus sylvatica (in Montseny). Of the total 43 VOCs detected, 23 were monoterpenes, 5 sesquiterpenes and 15 were not terpenes. Sesquiterpenes were the main terpenes emitted from T. tinctoria. Total VOC emission rates were on average about 15 times higher in summer than in early spring. The maximum rates of emission were recorded around midday. Emissions nearly stopped in the dark. No significant differences were found for nocturnal total terpene emission rates between places and seasons. The seasonal variations in the rate of terpene emissions and in their chemical composition can be explained mainly by dramatic changes in emission factors (emission capacity) associated in some cases, such as for beech trees, with very different foliar ontogenical characteristics between spring and summer. The results show that temperature and light-standardised emission rates were on average about 15 times higher in summer than in early spring, which, corroborating other works, calls to attention when applying the same emission factor in modelling throughout the different seasons of the year.

  20. Ecological dynamics of two remote alpine lakes during ice-free season

    Directory of Open Access Journals (Sweden)

    Rocco Tiberti

    2013-05-01

    Full Text Available We studied hydrochemistry and plankton dynamics in two remote alpine lakes: lake Nivolet superiore (2530 m asl and lake Trebecchi superiore (2729 m asl in the Gran Paradiso National Park (Western Italian Alps in summer 2009. The aim of this study was to enhance the understanding of natural ecological dynamics in the pelagic habitat of alpine lakes by enlarging the number of biotic and abiotic variables usually considered to this end and by increasing the frequency of samplings, generally low in remote lakes. During the eight samplings performed in 2009, chemical and physical variables were measured both in situ and in the laboratory. We also followed the dynamics of all the compartments of the naturally simplified trophic chain of the two lakes from pico-prokaryotes to phytoplankton and zooplankton. Our results confirm the oligotrophic, close-to-pristine state of lake Nivolet and lake Trebecchi as they are not affected by hydromorphological alterations, they are naturally fishless and are not sensitive to acidification risk and acidity pulses. On the other hand, the two lakes have distinct abiotic conditions due to their glacial origin and to the lithological composition of their watersheds. We found some differences in the spatial variation of pico-prokaryotes, phytoplankton and zooplankton due to the different mixing regimes and maximum depth of the two lakes. Conversely, temporal patterns were similar in both lakes, related to ecological interactions and to changes in the abiotic conditions. The rapid succession of events in extreme ecosystems, such as the alpine lakes studied here, confirm the predominant role of external environmental factors (e.g. the duration of the ice-free season and of ecological interactions among different trophic compartments. This research underlines the importance of seasonal niche partitioning among organisms with different size.

  1. Inter-Seasonal Variations of Surface Temperature in the Urbanized Environment of Delhi Using Landsat Thermal Data

    Directory of Open Access Journals (Sweden)

    Ram Babu Singh

    2014-03-01

    Full Text Available Complex land use/cover patterns in urban areas significantly influence their prevailing surface temperature conditions. As a result of differential cooling and heating of various land use/cover, large temperature ranges are associated with bare land, built-up land, etc. and low ranges are found in vegetation cover and water bodies. Extremely high and low temperature conditions in built-up land have direct and negative impacts on health conditions, and therefore are imperative to study. Thus, an attempt has been made in this research to analyze seasonal variations in surface temperature in city of Delhi. Landsat Thematic Mapper (TM 5 satellite images for the four seasons, viz., 16 January (winter, 5 March (spring, 8 May (summer and 29 September (autumn 2011 have been used to interpret the distribution and changes in surface temperature. A total of 80 samples from all land use/cover categories were taken to generalize the patterns along with north-south and west-east profiles. The extracted surface temperature patterns reflect the spatial and temporal dynamics of temperature over different land use/cover. The north-south and west-east gradient of temperature demonstrates that the core of Delhi has a much lower temperature and weak urban heat island (UHI phenomenon.

  2. Temporal variation (seasonal and interannual) of vegetation indices of maize and soybeans across multiple years in central Iowa

    Science.gov (United States)

    Prueger, J. H.; Hatfield, J. L.

    2015-09-01

    Remotely sensed reflectance parameters from corn and soybean surfaces can be correlated to crop production. Surface reflectance of a typical Upper Midwest corn /soybean region in central Iowa across multiple years reveal subtle dynamics in vegetative surface response to a continually varying climate. From 2006 through 2014 remotely sensed data have been acquired over production fields of corn and soybeans in central IA, U.S.A. with the fields alternating between corn and soybeans. The data have been acquired using ground-based radiometers with 16 wavebands covering the visible, near infrared, shortwave infrared wavebands and combined into a series of vegetative indices. These data were collected on clear days with the goal of collecting data at a minimum of once per week from prior to planting until after fall tillage operations. Within each field, five sites were established and sampled during the year to reduce spatial variation and allow for an assessment of changes in the vegetative indices throughout the growing season. Ancillary data collected for each crop included the phenological stage at each sampling date along with biomass sampled at the onset of the reproductive stage and at physiological maturity. Evaluation of the vegetative indices for the different years revealed that patterns were related to weather effects on corn and soybean growth. Remote sensing provides a method to evaluate changes within and among growing seasons to assess crop growth and development as affected by differences in weather variability.

  3. A STUDY OF SEASONAL VARIATION OBSERVED IN OCCURRENCE OF IMMINENT ECLAMPSIA AND ECLAMPSIA AT TERTIARY CARE HOSPITAL

    Directory of Open Access Journals (Sweden)

    Ashutosh

    2016-02-01

    Full Text Available BACKGROUND Eclampsia is an occurrence of seizures in women with pre-eclampsia. It is a leading cause of maternal mortality and morbidity in India. Their etiology is poorly understood even today. Seasonal variation is considered as one of the cause. AIMS AND OBJECTIVES To see the frequency of occurrence of imminent eclampsia and eclampsia during rainy (June to August and winter (October to December season. MATERIALS AND METHOD This is a descriptive, retrospective, observational and analytical study on seasonal variations in admission of imminent eclampsia and eclampsia patients in Department of Obstetrics and Gynaecology in KIMS, Karad, from 2012 to 2014. RESULT Among 9122 total number of admissions in Department of Obstetrics and Gynaecology 7678 got delivered in our institute. In which 4150 deliveries occurred in rainy season in which imminent eclampsia were 55 (1.3%, eclampsia cases were 42 (1.01%. While 3528 cases delivered in winter in which imminent eclampsia were 28 (0.7% and eclampsia were 24 (0.68%. The study showed frequency of imminent eclampsia and eclampsia being more common in rainy season than that of winter season. CONCLUSION In our study, we observed the seasonal variation in occurrence of imminent eclampsia and eclampsia. Number of cases of both imminent eclampsia and eclampsia was more common in rainy season. Regular health checkup, availability of health facilities and prompt referral to tertiary hospital can decrease mortality and morbidity of patient.

  4. Seasonal variation in rates of methane production from peat of various botanical origins: effects of temperature and substrate quality.

    Science.gov (United States)

    Bergman; Klarqvist; Nilsson

    2000-09-01

    The methane produced in peat soils can vary over the growing season due to variations in the supply of available substrate, the activity of the microbial community or changes in temperature. Our aim was to study how these factors regulate the methane production over the season from five different peat types of different botanical origin. Peat samples were collected on seven occasions between June and September. After each sampling, the peat soils were incubated at five different temperatures (7, 10, 15, 20 and 25 degrees C) without added substrate, or at 20 degrees C with added substrate (glucose, or H(2)/CO(2), or starch). Rates of methane production averaged over the season differed significantly (Pmethane production from each plant community varied significantly (Ptemperature, explains the seasonal variation in methane production. However, addition of saturating amounts of glucose, H(2)/CO(2) or starch at 20 degrees C significantly reduced the seasonal variation (Pmethane production in peat from the minerotrophic lawn, wet carpet and mud-bottom plant communities. This suggests that substrate supply (e.g. root exudates) for the micro-organisms also varied over the season at these sites. Seasonal variation in methane production rates was apparent in peat from the hummock and ombrotrophic lawn plant communities even after addition of substrates, suggesting that the active biomass of the anaerobic microbial populations at these sites was regulated by other factors than the ones studied.

  5. Seasonal Variation in the Distribution and Isotopic Composition of Phytoplankton in an Amazon Floodplain Lake, Brazil

    Directory of Open Access Journals (Sweden)

    Pedro Caraballo Gracia

    2014-03-01

    Full Text Available To evaluate the seasonal variation and isotopic composition of phytoplankton, water samples were collected monthly between October 2007 and November 2008 in Lake Catalão, a floodplain lake at the confluence between rivers Negro and Amazon. Analyses of total chlorophyll concentration and δ13C and δ15N isotopic abundances were made from particulate size fractions of 30-60, 10-30 and <10 µm in the littoral, pelagic, and floating meadows regions. Chlorophyll concentration was found to be inversely associated to lake depth, and high concentrations of chlorophyll in the floating meadows zone were significant.  The fraction <10 µm was the most abundant representing in average more than 40% of the particulate matter. The δ13C values were relatively constant during the study (-25.1‰ ~ -34.0‰, whereas the δ15N values showed strong variability (15.6‰ ~ 2.4‰, which has been attributed to the resuspension of sediments during mixing of the water column. Mixing associated to the sudden drop in temperature during the rising water period was an important event in the trophic and isotopic dynamics of the lake. Variations in chlorophyll content were generally associated with the dilution process, in which concentration was inversely correlated to the water level, whereas abundance was directly correlated to the water level.VARIACIÓN ESTACIONAL DE LA DISTRIBUCIÓN Y COMPOSICIÓN ISOTÓPICA DEL FITOPLANCTON EN UN LAGO DE INUNDACIÓN EN LA AMAZONIA, BRASIL. Con el propósito de evaluar la variación estacional de la abundancia isotópica (δ13C e δ15N del fitoplancton, muestreos mensuales fueron realizados entre octubre de 2007 y noviembre de 2008 en el lago Catalão, un lago de inundación en la zona de confluencia de los ríos Negro y Solimões, ubicado frente a la ciudad de Manaus (AM, Brasil. Análisis de la clorofila total y evaluaciones de la abundancia natural de δ13C y δ15N fueron realizados en las fracciones partículadas de 30-60, 10

  6. Seasonal variation and source apportionment of PAHs in TSP in the atmosphere of Guiyang, Southwest China

    Science.gov (United States)

    Hu, J.; Liu, C. Q.; Zhang, G. P.; Zhang, Y. L.

    2012-11-01

    Total suspended particle (TSP) samples were collected during January to December in 2005 at urban and rural sites in Guiyang, and were analyzed for 14 particulate-phase polycyclic aromatic hydrocarbons (P-PAHs) using High Performance Liquid Chromatography (HPLC) with fluorescence detection. The total concentration of the P-PAHs ranged from 6.0-29.1 ng/m3 at monitoring sites, and 1.2-84.8 ng/m3 in and around Guiyang. P-PAHs concentration in samples collected from Guiyang possesses distinct seasonal variation with a higher concentration in winter and lower concentration in summer. PAHs with 5-ring were found to have the most distinct seasonal variation among other target PAHs. Correlations between the TSP concentration, ambient temperature (T), relative humidity (RH), and the P-PAHs concentrations were evaluated. It was found that the TSP had significant influence on the P-PAHs concentration with correlation coefficients of 0.69 (P < 0.01, n = 180). In addition, the P-PAHs concentration showed negative correlation with RH (r = - 0.28, P < 0.01, n = 180), and a moderate negative correlation with T (r = - 0.17, P < 0.05 n = 180). Diagnostic ratios and Principal Component Analysis suggest that the main pollution sources identified were coal combustion emission (52.5%), traffic gasoline (21.4%) and other miscellaneous sources (14.2%).

  7. Intersexual and temporal variation in foraging ecology of prothonotary warblers during the breeding season

    Science.gov (United States)

    Petit, L.J.; Petit, D.R.; Petit, K.E.; Fleming, W.J.

    1990-01-01

    We studied foraging ecology of Prothonotary Warblers (Protonotaria citrea) over four breeding seasons to determine if this species exhibited sex-specific or temporal variation in foraging behavior. Significant differences between sexes during the prenestling period were found for foraging height and substrate height (foraging method, plant species/substrate, perch diameter, horizontal location from trunk, and prey location were not significantly different). During the nestling period, this divergence between sexes was evident for foraging height, substrate height, substrate / tree species, and prey location. Additionally, male warblers significantly altered their behavior for all seven foraging variables between the two periods, whereas females exhibited changes similar to those of males for five of the foraging variables. This parallel shift suggests a strong behavioral response by both sexes to proximate factors (such as vegetation structure, and prey abundance and distribution) that varied throughout the breeding season. Sex-specific foraging behavior during the prenestling period was best explained by differences in reproductive responsibilities rather than by the theory of intersexual competition for limited resources. During the nestling period, neither hypothesis by itself explained foraging divergences adequately. However, when integrated with the temporal responses of the warblers to changes in prey availability, reproductive responsibilities seemed to be of primary importance in explaining intersexual niche partitioning during the nestling period. We emphasize the importance of considering both intersexual and intraseasonal variation when quantifying a species' foraging ecology.

  8. Seasonal variations and aeration effects on water quality improvements and physiological responses of Nymphaea tetragona Georgi.

    Science.gov (United States)

    Lu, Xiao-Ming; Lu, Peng-Zhen; Huang, Min-Sheng; Dai, Ling-Peng

    2013-01-01

    Seasonal variations and aeration effects on water quality improvements and the physiological responses of Nymphaea tetragona Georgi were investigated with mesocosm experiments. Plants were hydroponically cultivated in six purifying tanks (aerated, non-aerated) and the characteristics of the plants were measured. Water quality improvements in purifying tanks were evaluated by comparing to the control tanks. The results showed that continuous aeration affected the plant morphology and physiology. The lengths of the roots, petioles and leaf limbs in aeration conditions were shorter than in non-aeration conditions. Chlorophyll and soluble protein contents of the leaf limbs in aerated tanks decreased, while peroxidase and catalase activities of roots tissues increased. In spring and summer, effects of aeration on the plants were less than in autumn. Total nitrogen (TN) and ammonia nitrogen (NH4(+)-N) in aerated tanks were lower than in non-aerated tanks, while total phosphorus (TP) and dissolved phosphorus (DP) increased in spring and summer. In autumn, effects of aeration on the plants became more significant. TN, NH4(+)-N, TP and DP became higher in aerated tanks than in non-aerated tanks in autumn. This work provided evidences for regulating aeration techniques based on seasonal variations of the plant physiology in restoring polluted stagnant water.

  9. A global survey on the seasonal variation of the marginal distribution of daily precipitation

    Science.gov (United States)

    Papalexiou, Simon Michael; Koutsoyiannis, Demetris

    2016-08-01

    To characterize the seasonal variation of the marginal distribution of daily precipitation, it is important to find which statistical characteristics of daily precipitation actually vary the most from month-to-month and which could be regarded to be invariant. Relevant to the latter issue is the question whether there is a single model capable to describe effectively the nonzero daily precipitation for every month worldwide. To study these questions we introduce and apply a novel test for seasonal variation (SV-Test) and explore the performance of two flexible distributions in a massive analysis of approximately 170,000 monthly daily precipitation records at more than 14,000 stations from all over the globe. The analysis indicates that: (a) the shape characteristics of the marginal distribution of daily precipitation, generally, vary over the months, (b) commonly used distributions such as the Exponential, Gamma, Weibull, Lognormal, and the Pareto, are incapable to describe "universally" the daily precipitation, (c) exponential-tail distributions like the Exponential, mixed Exponentials or the Gamma can severely underestimate the magnitude of extreme events and thus may be a wrong choice, and (d) the Burr type XII and the Generalized Gamma distributions are two good models, with the latter performing exceptionally well.

  10. Melanopsin Gene Variations Interact With Season to Predict Sleep Onset and Chronotype

    Science.gov (United States)

    Roecklein, Kathryn A.; Wong, Patricia M.; Franzen, Peter L.; Hasler, Brant P.; Wood-Vasey, W. Michael; Nimgaonkar, Vishwajit L.; Miller, Megan A.; Kepreos, Kyle M.; Ferrell, Robert E.; Manuck, Stephen B.

    2013-01-01

    The human melanopsin gene has been reported to mediate risk for seasonal affective disorder (SAD), which is hypothesized to be caused by decreased photic input during winter when light levels fall below threshold, resulting in differences in circadian phase and/or sleep. However, it is unclear if melanopsin increases risk of SAD by causing differences in sleep or circadian phase, or if those differences are symptoms of the mood disorder. To determine if melanopsin sequence variations are associated with differences in sleep-wake behavior among those not suffering from a mood disorder, the authors tested associations between melanopsin gene polymorphisms and self-reported sleep timing (sleep onset and wake time) in a community sample (N = 234) of non-Hispanic Caucasian participants (age 30–54 yrs) with no history of psychological, neurological, or sleep disorders. The authors also tested the effect of melanopsin variations on differences in preferred sleep and activity timing (i.e., chronotype), which may reflect differences in circadian phase, sleep homeostasis, or both. Daylength on the day of assessment was measured and included in analyses. DNA samples were genotyped for melanopsin gene polymorphisms using fluorescence polarization. P10L genotype interacted with daylength to predict self-reported sleep onset (interaction p seasonal patterns of recurrence or exacerbation. PMID:22881342

  11. 7Be content and its seasonal variation in the ground air around Hangzhou area

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Twice investigations around Hangzhou area show that 7Be content average in the ground air is 5.9 mBq.m-3.The content of 7Be is the highest in autumn-winter period reaching about 7.7 mBq.m-3;the next is in spring about 6.2 mBq.m-3;then is in the early summer about 5.7 mBq.m-3,close to the annual average level; and the lowest in a year is in summer-autumn period with a value about 3.8 mBq.m-3. Exhibited is a decreasing trend from autumn-winter period to summer-autumn of the next year,which is negatively correlated with the variation of the seasonal rainfall in Hangzhou area. But this trend is different from that reported by UNSCEAR: it is the highest in spring and the lowest in the late autumn, which is based only on 7Be falling down from the stratosphere. However, the present investigation shows that the seasonal rainfall is the main factor influencing the variation trend of 7Be content in the air.

  12. Spatiotemporal variation of precipitation based on three indicators in the flood season in Beijing

    Science.gov (United States)

    Chen, Y.; Wang, J. H.; Xiao, W. H.; Zhou, Y. Y.; Wang, L. T.; Song, X. Y.

    2016-08-01

    This paper attempts to analyze the spatiotemporal variation of precipitation in Beijing in terms of three indicators, i.e., the total precipitation, the maximum daily precipitation, and the maximum 5h precipitation in the flood season, with data collected from 20 meteorological stations from 1975 to 2012 (June to September). The Mann-Kendall nonparametric test, the linear regression, and five-year moving average were used. The results showed that: (i) the three indicators showed a decreasing trend; however, from 1975 to 1995 and from 1995 to 2012, the precipitation in the flood season showed an increasing trend with an increasing rate of 3.36 and 2.90mm/a, respectively. (ii) The indicators demonstrated a similar spatial variation. The high value precipitation areas were mainly in the northern and central parts of the city. The central districts had increasing centers with maximum increasing rates of 0.35, 0.65, and 0.49mm/a, respectively. However, the northern part exhibited different degrees of decreasing trends. (iii) The increase in the precipitation in the city center was mainly due to the urban heat island effect and the change in the underlying surface. The temperature gradient was intensified due to the topography in the city center and the northern suburb, causing a decreasing trend of precipitation.

  13. Seasonal and Interannual Variation in Energy Balance in the Semiarid Grassland Area of China

    Directory of Open Access Journals (Sweden)

    Qun’ou Jiang

    2015-01-01

    Full Text Available Near surface energy budget changes have been proved to be induced by the land cover conversion through changing the surface physical properties, which can further impact the regional climate change. This study applies the DLS model to simulate the land cover under the business as usual (BAU scenario and then analyses the seasonal and interannual variation of energy balance in the semiarid grassland area of China based on the simulated land cover with the Weather Research and Forecasting (WRF model. The results indicate that the grassland will show a growing trend under the BAU scenario. Downward long wave radiation and downward short wave radiation will all have small-scale increase with time going by, while the surface net radiation will decrease from 2030 to 2050. However, there is obvious seasonal variation. Summer has the highest downward long wave radiation and downward short wave radiation, followed by spring and autumn. The lowest are in winter. As for the net surface radiation, there is obvious decrease in southeast of study area due to returning cropland to grassland. Those research conclusions can offer valuable information for the land use planning and relieving the effects of land cover change on climate change at the semiarid grassland area.

  14. Seasonal variations and environmental control of water use efficiency in subtropical plantation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    <正>To understand the seasonal variations of water use efficiency (WUE) of coniferous plantation in the subtropical monsoon area, the experiment was conducted in 2003 and 2004 which presented two distinguished climatic conditions (severe summer drought in 2003 and normal climatic condition in 2004). The water stress influenced WUE greatly, which caused a special seasonal WUE pattern. WUE reached the minimum in summer drought and the maximum in winter, which was contrary to the variation of gross primary production (GPP) and canopy evaporation (Fw). In winter, GPP and Fw increased along with the increasing of air temperature and vapor pressure deficit (VPD), with the similar increasing rate. However, in drought summer, there was an adverse trend among GPP/Fw and air temperature and VPD, and the decreasing rate of GPP was far larger than that of Fw. In summer, the conservation of WUE was changed because of the environmental factors, resulting in the decreasing WUE. The photosynthesis and transpiration of vegetation were mainly controlled by the environmental factors in winter, and the impact of stomatal regulation was relatively weak. In summer, Fw was mainly controlled by the stomatal closure and GPP by both environmental factors and stomatal closure.

  15. Modeling Study of Seasonal Variation of the Pelagic-Benthic Ecosystem Characteristics of the Bohai Sea

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on experiment data of the Sino-German comprehensive investigations in the Bohai Sea in 1998 and 1999, a simple coupled pelagic-benthic ecosystem multi-box model is used to simulate the ecosystem seasonal variation. The pelagic sub-model consists of seven state variables: phytoplankton, zooplankton, TIN, TIP, DOC, POC and dissolved oxygen (DO). The benthic sub-model includes macro-benthos, meiobenthos, bacteria, detritus, TIN and TIP in the sediment. Besides the effects of solar radiation, water temperature and the nutrient from sea bottom exudation, land-based inputs are considered. The impact of the advection terms between the boxes is also considered. Meanwhile, the effects of the microbial-loop are introduced with a simple parameterization. The seasonal variations and the horizontal distributions of the ecosystem state variables of the Bohai Sea are simulated. Compared with the observations, the results of the multi-box model are reasonable. The modeled results show that about 13% of the photosynthesis primary production goes to the main food loop, 20% transfers to the benthic domain, 44% is consumed by the respiration of phytoplankton, and the rest goes to DOC. Model results also show the importance of the microbial food loop in the ecosystem of the Bohai Sea, and its contribution to the annual zooplankton production can be 60% - 64%.

  16. Seasonal variation of the Beaufort shelfbreak jet and its relationship to Arctic cetacean occurrence

    Science.gov (United States)

    Lin, Peigen; Pickart, Robert S.; Stafford, Kathleen M.; Moore, G. W. K.; Torres, Daniel J.; Bahr, Frank; Hu, Jianyu

    2016-12-01

    Using mooring time series from September 2008 to August 2012, together with ancillary atmospheric and satellite data sets, we quantify the seasonal variations of the shelfbreak jet in the Alaskan Beaufort Sea and explore connections to the occurrences of bowhead and beluga whales. Wind patterns during the 4 year study period are different from the long-term climatological conditions that the springtime peak in easterly winds shifted from May to June and the autumn peak was limited to October instead of extending farther into the fall. These changes were primarily due to the behavior of the two regional atmospheric centers of action, the Aleutian Low and Beaufort High. The volume transport of the shelfbreak jet, which peaks in the summer, was decomposed into a background (weak wind) component and a wind-driven component. The wind-driven component is correlated to the Pt. Barrow, AK alongcoast wind speed record although a more accurate prediction is obtained when considering the ice thickness at the mooring site. An upwelling index reveals that wind-driven upwelling is enhanced in June and October when storms are stronger and longer-lasting. The seasonal variation of Arctic cetacean occurrence is dominated by the eastward migration in spring, dictated by pack-ice patterns, and westward migration in fall, coincident with the autumn peak in shelfbreak upwelling intensity.

  17. Seasonal variations in diversity and abundance of surface ichthyoplankton in the northern South China Sea

    Institute of Scientific and Technical Information of China (English)

    LI Kaizhi; YIN Jianqiang; HUANG Liangmin; LIN Zhaojin

    2014-01-01

    The objective of this study was to investigate the seasonal variations of ichthyoplankton diversity and abun-dance in the northern South China Sea based on the data collected during summer, winter and spring. In total, 95 taxa of larval fishes were identified. The greatest number of species was recorded in spring, followed by summer and winter. The number of species was distributed mainly in the coastal waters from the east of Leizhou Peninsula to the southeast of Hainan Island during the surveyed periods of summer and spring, but in the offshore waters during winter. The abundance of larval fish was lowest in winter, increased in spring, and reached the maximum in summer. High abundance of larval fish was generally restricted to coastal waters with the isobaths less than 50 m. Seasonal variations of larval fish richness, abundance and diversity index were significant (P<0.001). Carangidae was the most common and abundant taxon in summer and winter, whileSardinella sp.,Thrissa mystax andLeiognathus sp. were dominant in spring. High diversity and abundance of larval fish might be attributed to increased temperature and coastal upwelling in spring and summer.

  18. Short-Term Dynamics Reveals Seasonality in a Subtropical Heliconius Butterfly

    Directory of Open Access Journals (Sweden)

    Thadeu Sobral-Souza

    2015-01-01

    Full Text Available Although tropical insect populations are generally regarded as constant and stable over time, some of these tropical populations, including butterflies, may fluctuate according to precipitation and temperature variation, specialized feeding patterns, and density-dependent factors. Heliconiini butterfly populations are generally regarded as stable over time because of the presence of host-plants and absence of diapause. However, peaks of abundance occur in subtropical Heliconius populations, and opposite trends concerning stability are found in the literature. Here we further investigate the dynamics of subtropical Heliconius butterflies by assessing a population of the species Heliconius sara apseudes from southeastern Brazil. We estimated individual apparent survival probability and population growth rate while accounting for the imperfect detectability of individuals using mark-recapture models to evaluate the population dynamics. Adult males presented slightly higher weekly survival estimates than females. Contrary to the common pattern described in the literature for Heliconius populations we observed a rapid decline on the adult population by the end of the mating season, possibly leading to local extinction. We discuss the potential drivers for such dynamics.

  19. Evaluating influences of seasonal variations and anthropogenic activities on alluvial groundwater hydrochemistry using ensemble learning approaches

    Science.gov (United States)

    Singh, Kunwar P.; Gupta, Shikha; Mohan, Dinesh

    2014-04-01

    Chemical composition and hydrochemistry of groundwater is influenced by the seasonal variations and anthropogenic activities in a region. Understanding of such influences and responsible factors is vital for the effective management of groundwater. In this study, ensemble learning based classification and regression models are constructed and applied to the groundwater hydrochemistry data of Unnao and Ghaziabad regions of northern India. Accordingly, single decision tree (SDT), decision tree forest (DTF), and decision treeboost (DTB) models were constructed. Predictive and generalization abilities of the proposed models were investigated using several statistical parameters and compared with the support vector machines (SVM) method. The DT and SVM models discriminated the groundwater in shallow and deep aquifers, industrial and non-industrial areas, and pre- and post-monsoon seasons rendering misclassification rate (MR) between 1.52-14.92% (SDT); 0.91-6.52% (DTF); 0.61-5.27% (DTB), and 1.52-11.69% (SVM), respectively. The respective regression models yielded a correlation between measured and predicted values of COD and root mean squared error of 0.874, 0.66 (SDT); 0.952, 0.48 (DTF); 0.943, 0.52 (DTB); and 0.785, 0.85 (SVR) in complete data array of Ghaziabad. The DTF and DTB models outperformed the SVM both in classification and regression. It may be noted that incorporation of the bagging and stochastic gradient boosting algorithms in DTF and DTB models, respectively resulted in their enhanced predictive ability. The proposed ensemble models successfully delineated the influences of seasonal variations and anthropogenic activities on groundwater hydrochemistry and can be used as effective tools for forecasting the chemical composition of groundwater for its management.

  20. Water chemistry in Kuji river. Its spatial and seasonal variations in major ions and organic substances

    Energy Technology Data Exchange (ETDEWEB)

    Niina, Toshiaki; Matsunaga, Takeshi; Amano, Hikaru [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1996-02-01

    As a basic research with a aim to clarify the migration behavior of radionuclides in rivers, the characteristics of dissolved ions and organic substances in river water, which characteristics may affect the behavior, was investigated. The investigation was carried out for the Kuji river in the northern Kanto district (Japan) comprising four sampling campaigns in 1994 for 10 locations from the upstream to the downstream. Concentrations of major ions, iron and manganese species and organic substances were analyzed in laboratory. Values of temperature of the water, pH, conductivity, dissolved oxygen were measured in the field. This investigation was conducted mainly under low water flow conditions of the river, while a limited number of campaigns were under high flow conditions due to precipitation events. The concentrations of major inorganic ions increased steadily toward the down-stream, resulting in approximately two times increase for the traveling distance of 100 km. They showed a seasonal variation that they were highest in the spring and lowest in the autumn when there were most concentrated precipitation events in a year. The constituents were mainly Na{sup +}, Ca{sup 2+}, SO{sub 4}{sup 2-} and HCO{sub 3}{sup -}, and were similar for every sampling locations and seasons. Concentrations of dissolved organic substances (carbon compounds) were lowest in the upstream and increased about twice in the downstream as well as major inorganic ions. Their level was 1-3 mg/l, which can be ranked as relatively lower in general values for fresh water environments. They were highest in the spring (average over the locations: 2.2 mg/l) and lowest in the autumn (1.3 mg/l) and also in the winter (1.3 mg/l). These results will be useful as a basic understanding of spatial and seasonal variations of river water chemistry, especially related to the organic substances which can bind with radionuclides to make a mobile complex. (author).

  1. Seasonal dynamics of ichthyodiversity in a hill stream of the Darjeeling Himalaya, West Bengal, india

    Directory of Open Access Journals (Sweden)

    M.L. Acharjee

    2014-12-01

    Full Text Available The small torrential spring-fed hill-stream Relli in the Darjeeling Himalaya of West Bengal was studied from March 2007 to February 2009 to assess seasonal dynamics and diversity of fish populations.  The study revealed that the stream sustained 25 rheophilic cold water fish species from 15 genera and five families having ornamental, food and sport value.  Seven omnivorous species were abundantly found, and the array of juveniles and sub adults suggests this stream is used as a breeding and nursery ground for some species.  The stream harboured fish with unique modifications such as adhesive structures.  Analysis of monthly data indicate that abundance and diversity indices increased slightly during April–May and sharply during October–November, indicating significant seasonal variations with the low diversity observed during monsoon months reflecting environmental stresses.  Evenness was high in all sampling sites, and inversely related to the dominance index of ichthyofauna.  The density and diversity of fish assemblages along the gradient of the stream may be interrupted due to anthropogenic disturbances.  Our study provides baseline data which may be helpful for conservation and management of fish species, and in formulating fishery policy. 

  2. Effect of diurnal and seasonal temperature variation on Cussac cave ventilation using co2 assessment

    Science.gov (United States)

    Peyraube, Nicolas; Lastennet, Roland; Villanueva, Jessica Denila; Houillon, Nicolas; Malaurent, Philippe; Denis, Alain

    2016-05-01

    Cussac cave was investigated to assess the cave air temperature variations and to understand its ventilation regime. This cave is located in an active karst system in the south west part of France. It has a single entrance and is considered as a cold air trap. In this study, air mass exchanges were probed. Measurements of temperature and Pco2 with a 30-min frequency were made in several locations close to the cave entrance. Speed of the air flow was also measured at the door of cave entrance. Results show that cave air Pco2 varies from 0.18 to 3.33 %. This cave appears to be a CO2 source with a net mass of 2319 tons blown in 2009. Carbon-stable isotope of CO2 (13Cco2) ranges from -20.6 ‰ in cold season to -23.8 ‰ in warm season. Cave air is interpreted as a result of a mix between external air and an isotopically depleted air, coming from the rock environment. The isotopic value of the light member varies through time, from -23.9 to -22.5 ‰. Furthermore, this study ascertains that the cave never stops in communicating with the external air. The ventilation regime is identified. (1) In cold season, the cave inhales at night and blows a little at the warmest hours. However, in warm season, (2) cave blows at night, but (3) during the day, a convection loop takes place in the entrance area and prevents the external air from entering the cave, confirming the cold air trap.

  3. Effect of diurnal and seasonal temperature variation on Cussac cave ventilation using co2 assessment

    Science.gov (United States)

    Peyraube, Nicolas; Lastennet, Roland; Villanueva, Jessica Denila; Houillon, Nicolas; Malaurent, Philippe; Denis, Alain

    2017-08-01

    Cussac cave was investigated to assess the cave air temperature variations and to understand its ventilation regime. This cave is located in an active karst system in the south west part of France. It has a single entrance and is considered as a cold air trap. In this study, air mass exchanges were probed. Measurements of temperature and Pco2 with a 30-min frequency were made in several locations close to the cave entrance. Speed of the air flow was also measured at the door of cave entrance. Results show that cave air Pco2 varies from 0.18 to 3.33 %. This cave appears to be a CO2 source with a net mass of 2319 tons blown in 2009. Carbon-stable isotope of CO2 (13Cco2) ranges from -20.6 ‰ in cold season to -23.8 ‰ in warm season. Cave air is interpreted as a result of a mix between external air and an isotopically depleted air, coming from the rock environment. The isotopic value of the light member varies through time, from -23.9 to -22.5 ‰. Furthermore, this study ascertains that the cave never stops in communicating with the external air. The ventilation regime is identified. (1) In cold season, the cave inhales at night and blows a little at the warmest hours. However, in warm season, (2) cave blows at night, but (3) during the day, a convection loop takes place in the entrance area and prevents the external air from entering the cave, confirming the cold air trap.

  4. Understanding spatio-temporal variation of vegetation phenology and rainfall seasonality in the monsoon Southeast Asia.

    Science.gov (United States)

    Suepa, Tanita; Qi, Jiaguo; Lawawirojwong, Siam; Messina, Joseph P

    2016-05-01

    The spatio-temporal characteristics of remote sensing are considered to be the primary advantage in environmental studies. With long-term and frequent satellite observations, it is possible to monitor changes in key biophysical attributes such as phenological characteristics, and relate them to climate change by examining their correlations. Although a number of remote sensing methods have been developed to quantify vegetation seasonal cycles using time-series of vegetation indices, there is limited effort to explore and monitor changes and trends of vegetation phenology in the Monsoon Southeast Asia, which is adversely affected by changes in the Asian monsoon climate. In this study, MODIS EVI and TRMM time series data, along with field survey data, were analyzed to quantify phenological patterns and trends in the Monsoon Southeast Asia during 2001-2010 period and assess their relationship with climate change in the region. The results revealed a great regional variability and inter-annual fluctuation in vegetation phenology. The phenological patterns varied spatially across the region and they were strongly correlated with climate variations and land use patterns. The overall phenological trends appeared to shift towards a later and slightly longer growing season up to 14 days from 2001 to 2010. Interestingly, the corresponding rainy season seemed to have started earlier and ended later, resulting in a slightly longer wet season extending up to 7 days, while the total amount of rainfall in the region decreased during the same time period. The phenological shifts and changes in vegetation growth appeared to be associated with climate events such as EL Niño in 2005. Furthermore, rainfall seemed to be the dominant force driving the phenological changes in naturally vegetated areas and rainfed croplands, whereas land use management was the key factor in irrigated agricultural areas.

  5. Seasonal Temperature Variations controlling Cave Ventilation Processes in Cueva Larga, Puerto Rico

    Science.gov (United States)

    Winter, A.; Vieten, R.; Warken, S. F.; Schrӧder-Ritzrau, A.; Miller, T. E.; Scholz, D.

    2016-12-01

    Two years of monthly monitoring result in much better understanding of ventilation processes in caves. Cueva Larga, a tropical cave in Puerto Rico is 1440 m long with a large main passage (about 116,000 m3). Cave air pCO2 in the main passage varied seasonally, between 600 ppm in winter and 1800 ppm in summer. The seasonal variability in cave pCO2 made it possible to estimate a cave air exchange time of 36±5 days and a winter ventilation rate of 3,200±800 m3/day for the main cave passage. Calculations of virtual temperature and differences between cave and surface temperature show that the seasonal temperature cycle is the main driver of the alternation between a well-ventilated winter mode and a near-stagnant summer mode. The winter mode is characterized by a positive buoyancy contrast at night leading to maximal cave ventilation, while during summer ventilation is at a minimum. Between winter and summer, a transitional mode of partial cave ventilation is observed. On shorter time scales (diurnal to weekly), cave pCO2 is also influenced by atmospheric pressure but this variation is one order of magnitude lower than the seasonal pCO2 change. The cave morphology of Cueva Larga including its large volume, tubular shape and the obstructed cave entrance geometry are important boundary conditions for the observed ventilation patterns. Our findings emphasize that cave systems with varying morphology have to be studied individually in order to correctly describe ventilation processes.

  6. Seasonal temperature variations controlling cave ventilation processes in Cueva Larga, Puerto Rico

    Directory of Open Access Journals (Sweden)

    Rolf Vieten

    2016-09-01

    Full Text Available Two years of cave monitoring investigate ventilation processes in Cueva Larga, a tropical cave in Puerto Rico. The cave is 1,440 m long with a large main passage (about 120,000 m3. Cave air pCO2 in the main passage varies seasonally, between 600 ppm in winter and 1,800 ppm in summer. The seasonal variability in cave pCO2 permits the estimation of a cave air exchange time of 36 ± 5 days and a winter ventilation rate of 3,300 ± 1,000 m3/day for the main cave passage. Calculations of virtual temperature and differences between cave and surface temperature indicate that the seasonal temperature cycle is the main driver of the alternation between a well-ventilated winter mode and a near-stagnant summer mode. The winter mode is characterized by a positive buoyancy contrast at night leading to maximal cave ventilation, while cave ventilation is at a minimum during summer. Between winter and summer, a transitional mode of partial cave ventilation is observed. On shorter time scales (diurnal to weekly, cave pCO2 is also influenced by atmospheric pressure but this variation is one order of magnitude lower than the seasonal pCO2 change. The cave morphology of Cueva Larga including its large volume, tubular shape and the obstructed cave entrance geometry are important boundary conditions for the observed ventilation patterns. Our findings emphasize that cave systems with varying morphology have to be studied individually in order to correctly describe ventilation processes.

  7. Seasonal and temporal variation in release of antibiotics in hospital wastewater: estimation using continuous and grab sampling.

    Directory of Open Access Journals (Sweden)

    Vishal Diwan

    Full Text Available The presence of antibiotics in the environment and their subsequent impact on resistance development has raised concerns globally. Hospitals are a major source of antibiotics released into the environment. To reduce these residues, research to improve knowledge of the dynamics of antibiotic release from hospitals is essential. Therefore, we undertook a study to estimate seasonal and temporal variation in antibiotic release from two hospitals in India over a period of two years. For this, 6 sampling sessions of 24 hours each were conducted in the three prominent seasons of India, at all wastewater outlets of the two hospitals, using continuous and grab sampling methods. An in-house wastewater sampler was designed for continuous sampling. Eight antibiotics from four major antibiotic groups were selected for the study. To understand the temporal pattern of antibiotic release, each of the 24-hour sessions were divided in three sub-sampling sessions of 8 hours each. Solid phase extraction followed by liquid chromatography/tandem mass spectrometry (LC-MS/MS was used to determine the antibiotic residues. Six of the eight antibiotics studied were detected in the wastewater samples. Both continuous and grab sampling methods indicated that the highest quantities of fluoroquinolones were released in winter followed by the rainy season and the summer. No temporal pattern in antibiotic release was detected. In general, in a common timeframe, continuous sampling showed less concentration of antibiotics in wastewater as compared to grab sampling. It is suggested that continuous sampling should be the method of choice as grab sampling gives erroneous results, it being indicative of the quantities of antibiotics present in wastewater only at the time of sampling. Based on our studies, calculations indicate that from hospitals in India, an estimated 89, 1 and 25 ng/L/day of fluroquinolones, metronidazole and sulfamethoxazole respectively, might be getting

  8. Seasonal and Temporal Variation in Release of Antibiotics in Hospital Wastewater: Estimation Using Continuous and Grab Sampling

    Science.gov (United States)

    Diwan, Vishal; Stålsby Lundborg, Cecilia; Tamhankar, Ashok J.

    2013-01-01

    The presence of antibiotics in the environment and their subsequent impact on resistance development has raised concerns globally. Hospitals are a major source of antibiotics released into the environment. To reduce these residues, research to improve knowledge of the dynamics of antibiotic release from hospitals is essential. Therefore, we undertook a study to estimate seasonal and temporal variation in antibiotic release from two hospitals in India over a period of two years. For this, 6 sampling sessions of 24 hours each were conducted in the three prominent seasons of India, at all wastewater outlets of the two hospitals, using continuous and grab sampling methods. An in-house wastewater sampler was designed for continuous sampling. Eight antibiotics from four major antibiotic groups were selected for the study. To understand the temporal pattern of antibiotic release, each of the 24-hour sessions were divided in three sub-sampling sessions of 8 hours each. Solid phase extraction followed by liquid chromatography/tandem mass spectrometry (LC-MS/MS) was used to determine the antibiotic residues. Six of the eight antibiotics studied were detected in the wastewater samples. Both continuous and grab sampling methods indicated that the highest quantities of fluoroquinolones were released in winter followed by the rainy season and the summer. No temporal pattern in antibiotic release was detected. In general, in a common timeframe, continuous sampling showed less concentration of antibiotics in wastewater as compared to grab sampling. It is suggested that continuous sampling should be the method of choice as grab sampling gives erroneous results, it being indicative of the quantities of antibiotics present in wastewater only at the time of sampling. Based on our studies, calculations indicate that from hospitals in India, an estimated 89, 1 and 25 ng/L/day of fluroquinolones, metronidazole and sulfamethoxazole respectively, might be getting released into the

  9. Seasonal variations of aerosol over Dona Paula, a coastal site on the west coast of India

    Science.gov (United States)

    Suresh, T.; Desa, Elgar

    We report here the observations of the aerosol studies carried-out for three years (2000-2002) at Dona-Paula, Goa (15.456°N, 73.801°E), a coastal site on the west coast of India. Aerosol optical depths were measured using a five channel sunphotometer with wavelengths at 440, 500, 675, 870 and 936 nm. The site enjoys a tropical climate and is under the influence of the strong southwest or summer monsoon and weak northeast or winter monsoon. Being a coastal station land-sea breeze play an important role in the variations of the aerosol loading over the site and their transport to the Arabian Sea. The mean aerosol optical thicknesses (AOT) at 500 and 870 nm are 0.46 (±0.15) and 0.23 (±0.097), respectively, while the Angstrom exponent is 1.31 (±0.347). The aerosol properties over the site showed a distinct seasonal variations, with high values of AOT observed during summer, with mean values of 0.48 (±0.15) and 0.26 (±0.09) at 500 and 870 nm, respectively, while during the winter relatively low values were observed, with mean value of 0.41 (±0.14) and 0.19 (±0.09) at 500 and 870 nm, respectively. The values of Angstrom exponents observed at the site suggest that the aerosol comprise mostly of the small size particles, with relatively larger particles being observed during summer than winter. An anti-correlation is observed between the inter-annual variations in the aerosol loading and the rainfall over Goa. Aerosol properties show diurnal variations, with comparatively lower values of AOT being observed in the evening. These diurnal variations are within a limit of 10% of the average values observed for the day. Seasonal patterns in the diurnal variations of aerosol optical depths have been observed. Considering the effect of the meteorological parameters over the aerosol, it is observed that the AOT is positively correlated with water vapor column, however the wind is found to aid in the reduction of aerosol load over Goa. It can be inferred from the weak

  10. Phytoplankton dynamics of a tropical river: A dry and rainy season ...

    African Journals Online (AJOL)

    ... dynamics of a tropical river: A dry and rainy season comparison. ... Qualitative phytoplankton samples were collected by towing 55 ìm mesh plankton net while quantitative samples were obtained by sedimenting a known volume of water ...

  11. Muskrat population dynamics and vegetation utilization : A management plan : Report on 1980 field season

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Report for the 1980 field season on a study of muskrat population dynamics and vegetation utilization, being led by Utah State University for a doctorate...

  12. Seasonal frost effects on the dynamic behavior of a twenty-story office building

    Science.gov (United States)

    Yang, Z.; Dutta, U.; Xiong, F.; Biswas, N.; Benz, H.

    2008-01-01

    Studies have shown that seasonal frost can significantly affect the seismic behavior of a bridge foundation system in cold regions. However, little information could be found regarding seasonal frost effects on the dynamic behavior of buildings. Based on the analysis of building vibration data recorded by a permanent strong-motion instrumentation system, the objective of this paper is to show that seasonal frost can impact the building dynamic behavior and the magnitude of impact may be different for different structures. Ambient noise and seismic data recorded on a twenty-story steel-frame building have been analyzed to examine the building dynamic characteristics in relationship to the seasonal frost and other variables including ground shaking intensity. Subsequently, Finite Element modeling of the foundation-soil system and the building superstructure was conducted to verify the seasonal frost effects. The Finite Element modeling was later extended to a reinforced-concrete (RC) type building assumed to exist at a similar site as the steel-frame building. Results show that the seasonal frost has great impact on the foundation stiffness in the horizontal direction and a clear influence on the building dynamic behavior. If other conditions remain the same, the effects of seasonal frost on structural dynamic behavior may be much more prominent for RC-type buildings than for steel-frame buildings. ?? 2007 Elsevier B.V. All rights reserved.

  13. Seasonal and Day-to-day Variations of Thermospheric Tides and Dynamo Fields Studied with a Long-term Whole Atmosphere-Ionosphere Coupled Simulation

    Science.gov (United States)

    Jin, H.; Miyoshi, Y.; Fujiwara, H.; Shinagawa, H.

    2014-12-01

    Day-to-day and longer variations of ionospheric electron density, which affect various space weather applications, are caused originally from the solar activity variations and the rotation of the sun as well as the lower atmospheric activity. For the latter source, atmospheric waves such as tides and planetary waves are generated in the moist convection, which propagate through the middle atmosphere affected by various dynamical processes such as their interactions with the mean zonal wind and other waves, and reach the lower thermosphere where they induce dynamo electric fields. According to the recent satellite and ground-based observations, the characteristics of tides and planetary waves in the lower thermosphere are becoming known more clearly, such as the seasonal and latitude variations of major tides, planetary wave-like oscillations, and irregular variations during stratospheric sudden warming, and so on. In this paper, we use a whole atmosphere-ionosphere coupled model called GAIA, and have carried out a simulation from 1996 to 2013 with realistic forcing from the lower atmosphere by nudging the meteorological reanalysis (JRA) into the model. By analyzing the long-term model data, we investigate how the tidal variability and planetary waves in the lower thermosphere produce the seasonal and day-to-day variations in the dynamo electric field as well as the origin of the variations in the lower and middle atmospheres.

  14. Monitoring Grassland Seasonal Carbon Dynamics, by Integrating MODIS NDVI, Proximal Optical Sampling, and Eddy Covariance Measurements

    Directory of Open Access Journals (Sweden)

    Enrica Nestola

    2016-03-01

    Full Text Available This study evaluated the seasonal productivity of a prairie grassland (Mattheis Ranch, in Alberta, Canada using a combination of remote sensing, eddy covariance, and field sampling collected in 2012–2013. A primary objective was to evaluate different ways of parameterizing the light-use efficiency (LUE model for assessing net ecosystem fluxes at two sites with contrasting productivity. Three variations on the NDVI (Normalized Difference Vegetation Index, differing by formula and footprint, were derived: (1 a narrow-band NDVI (NDVI680,800, derived from mobile field spectrometer readings; (2 a broad-band proxy NDVI (derived from an automated optical phenology station consisting of broad-band radiometers; and (3 a satellite NDVI (derived from MODIS AQUA and TERRA sensors. Harvested biomass, net CO2 flux, and NDVI values were compared to provide a basis for assessing seasonal ecosystem productivity and gap filling of tower flux data. All three NDVIs provided good estimates of dry green biomass and were able to clearly show seasonal changes in vegetation growth and senescence, confirming their utility as metrics of productivity. When relating fluxes and optical measurements, temporal aggregation periods were considered to determine the impact of aggregation on model accuracy. NDVI values from the different methods were also calibrated against fAPARgreen (the fraction of photosynthetically active radiation absorbed by green vegetation values to parameterize the APARgreen (absorbed PAR term of the LUE (light use efficiency model for comparison with measured fluxes. While efficiency was assumed to be constant in the model, this analysis revealed hysteresis in the seasonal relationships between fluxes and optical measurements, suggesting a slight change in efficiency between the first and second half of the growing season. Consequently, the best results were obtained by splitting the data into two stages, a greening phase and a senescence phase, and

  15. Seasonal variation of Microcystis in Lake Taihu and its relationships with environmental factors

    Institute of Scientific and Technical Information of China (English)

    TAN Xiao; KONG Fanxiang; ZENG Qingfei; CAO Huansheng; QIAN Shanqin; ZHANG Min

    2009-01-01

    In order to monitor the changes of Microcystis along with temporal and spatial variations, seasonal variation of Microcystis in Lake Taihu was investigated by 16S-23S rRNA internal transcribed spacer denaturing gradient gel electrophoresis (16S-23S rRNA-ITS DGGE) and microscopic evaluation. Samples were collected quarterly at four sites (River Mouth, Meiliang Bay, Cross Area, and Lake Center) from August 2006 to April 2007. Results showed that Microcystis dominated total phytoplankton abundance at the four sites in all seasons except winter. The average annual abundance of Microcystis was relatively high at River Mouth and Meiliang Bay, reaching 81.22×106 and 61.32×106 cells/L, respectively. For temporal variations, Shannon-Wiener diversity index (H') according to DGGE profile revealed the richness of Microcystis in summer (H'=1.375±0.034) and winter (H'=1.650±0.032) was lower than that in spring (H'=2.078±0.031) and autumn (H'=2.365±0.032) (P0.05). Canonical correspondence analysis (CCA) was performed to elucidate the relationships between Microcystis operational taxonomic units (OTUs) composition and the environmental factors. Results of CCA revealed that temperature was strongly positively correlated with the first axis (r=0.963), while TSS was negative correlated with the second axis (r=-0.716). Phylogenetic tree based on the sequencing results of target bands on DGGE gel indicated that samples collected in summer and winter constituted two separated clusters.

  16. Measurement of black carbon at Syowa station, Antarctica: seasonal variation, transport processes and pathways

    Directory of Open Access Journals (Sweden)

    K. Hara

    2008-05-01

    Full Text Available Measurement of black carbon (BC was carried out at Syowa station Antarctica (69° S, 39° E from February 2004 until January 2007. The BC concentration at Syowa ranged from below detection to 176 ng m−3 during the measurements. Higher BC concentrations were observed mostly under strong wind (blizzard conditions due to the approach of a cyclone and blocking event. The BC-rich air masses traveled from the lower troposphere of the Atlantic and Indian Oceans to Syowa (Antarctic coast. During the summer (November–February, the BC concentration showed a diurnal variation together with surface wind speed and increased in the katabatic wind from the Antarctic continent. Considering the low BC source strength in the Antarctic continent, the higher BC concentration in the continental air (katabatic wind might be caused by long range transport of BC via the free troposphere from mid- and low- latitudes. The seasonal variation of BC at Syowa had a maximum in August, while at the other coastal stations (Halley, Neumayer, and Ferraz and the continental station (Amundsen-Scott, the maximum occurred in October. This difference may result from different transport pathways and scavenging of BC by precipitation during the transport from the source regions. During the austral summer, long-range transport of BC via the free troposphere is likely to make an important contribution to the ambient BC concentration. The BC transport flux indicated that BC injection into the Antarctic region strongly depended on the frequency of storm (blizzard conditions. The seasonal variation of BC transport flux increased by 290 mg m−2 month−1 in winter–spring when blizzards frequently occurred, whereas the flux decreased to lower than 50 mg m−2 month−1 in the summer with infrequent blizzards.

  17. Seasonal variation of black carbon over the South China Sea and in various continental locations in South China

    Directory of Open Access Journals (Sweden)

    D. Wu

    2013-07-01

    Full Text Available Black carbon (BC is an important atmospheric constitute as an air pollutant and as a climate forcer. To our knowledge, field measurements of BC have not been reported over the South China Sea. Observation of light absorption coefficients (σabs and BC concentrations by Aethalometer were conducted on Yongxing Island in the South China Sea and at five continental sites in the Pearl River Delta (PRD region, South China during the South China Sea monsoon period (rainy season, 16 May–20 June 2008 and the northeast monsoon period (dry season, 12 December 2008–8 January 2009. At the oceanic site, the daily average BC concentrations vary from 0.28 to 2.14 μg m−3 and seasonal variations of BC were small (0.67 in dry season and 0.54 μg m−3 in rainy season. Similarly, little seasonal difference was found at a background site in PRD (2.88 in dry season and 2.62 μg m−3 in rainy season. At PRD urban sites, the daily average concentration of BC ranges from 1.56 to 37.9 μg m−3, higher in the dry season (12.6 μg m−3 and lower in the rainy season (6.4 μg m−3. The observed average σabs values in rainy vs. dry seasons are 119 vs. 62 Mm−1 at the PRD urban sites, 29 vs. 26 Mm−1 at the PRD background site, and 8.4 vs. 7.2 Mm−1 at the marine site. A bi-peak pattern in diurnal BC variation was observed at all sites while this pattern is the most prominent at the urban sites. The first peak appears in the early morning rush hour and the second peak in early evening, with the evening peak more pronounced in dry season.

  18. Seasonal variation of serotonin turnover in human cerebrospinal fluid, depressive symptoms and the role of the 5-HTTLPR.

    Science.gov (United States)

    Luykx, J J; Bakker, S C; van Geloven, N; Eijkemans, M J C; Horvath, S; Lentjes, E; Boks, M P M; Strengman, E; DeYoung, J; Buizer-Voskamp, J E; Cantor, R M; Lu, A; van Dongen, E P A; Borgdorff, P; Bruins, P; Kahn, R S; Ophoff, R A

    2013-10-08

    Studying monoaminergic seasonality is likely to improve our understanding of neurobiological mechanisms underlying season-associated physiological and pathophysiological behavior. Studies of monoaminergic seasonality and the influence of the serotonin-transporter-linked polymorphic region (5-HTTLPR) on serotonin seasonality have yielded conflicting results, possibly due to lack of power and absence of multi-year analyses. We aimed to assess the extent of seasonal monoamine turnover and examined the possible involvement of the 5-HTTLPR. To determine the influence of seasonality on monoamine turnover, 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) were measured in the cerebrospinal fluid of 479 human subjects collected during a 3-year period. Cosine and non-parametric seasonal modeling were applied to both metabolites. We computed serotonin (5-HT) seasonality values and performed an association analysis with the s/l alleles of the 5-HTTLPR. Depressive symptomatology was assessed using the Beck Depression Inventory-II. Circannual variation in 5-HIAA fitted a spring-peak cosine model that was significantly associated with sampling month (P=0.0074). Season of sampling explained 5.4% (P=1.57 × 10(-7)) of the variance in 5-HIAA concentrations. The 5-HTTLPR s-allele was associated with increased 5-HIAA seasonality (standardized regression coefficient=0.12, P=0.020, N=393). 5-HIAA seasonality correlated with depressive symptoms (Spearman's rho=0.13, P=0.018, N=345). In conclusion, we highlight a dose-dependent association of the 5-HTTLPR with 5-HIAA seasonality and a positive correlation between 5-HIAA seasonality and depressive symptomatology. The presented data set the stage for follow-up in clinical populations with a role for seasonality, such as affective disorders.

  19. Dynamically downscaled multi-model ensemble seasonal forecasts over Ethiopia

    Science.gov (United States)

    Asharaf, Shakeel; Fröhlich, Kristina; Fernandez, Jesus; Cardoso, Rita; Nikulin, Grigory; Früh, Barbara

    2016-04-01

    Truthful and reliable seasonal rainfall predictions have an important social and economic value for the east African countries as their economy is highly dependent on rain-fed agriculture and pastoral systems. Only June to September (JJAS) seasonal rainfall accounts to more than 80% crop production in Ethiopia. Hence, seasonal foresting is a crucial concern for the region. The European Provision of Regional Impact Assessment on a seasonal to decadal timescale (EUPORIAS) project offers a common framework to understand hindcast uncertainties through the use of multi-model and multi-member simulations over east Africa. Under this program, the participating regional climate models (RCMs) were driven by the atmospheric-only version of the ECEARTH global climate model, which provides hindcasts of a five-months period (May to September) from 1991-2012. In this study the RCMs downscaled rainfall is evaluated with respect to the observed JJAS rainfall over Ethiopia. Both deterministic and probabilistic based forecast skills are assessed. Our preliminary results show the potential usefulness of multi-model ensemble simulations in forecasting the seasonal rainfall over the region.

  20. Groundwater capture processes under a seasonal variation in natural recharge and discharge

    Science.gov (United States)

    Maddock, Thomas, III.; Vionnet, Leticia Beatriz

    "Capture" is the increase in recharge and the decrease in discharge that occurs when pumping is imposed on an aquifer system that was in a previous state of approximate dynamic equilibrium. Regional groundwater models are usually used to calculate capture in a two-step procedure. A steady-state solution provides an initial-head configuration, a set of flows through the boundaries for the modeled region, and the initial basis for the capture calculation. The transient solutions provide the total change in flows through the boundaries. A difference between the transient and steady-state solutions renders the capture calculation. When seasonality is a modeling issue, the use of a single initial hydraulic head and a single set of boundary flows leads to miscalculations of capture. Instead, an initial condition for each season should be used. This approach may be accomplished by determining steady oscillatory solutions, which vary through the seasons but repeat from year to year. A regional groundwater model previously developed for a portion of the San Pedro River basin, Arizona, USA, is modified to illustrate the effect that different initial conditions have on transient solutions and on capture calculations. Résumé Les "prélèvements" sont constitués par l'augmentation de la recharge et par la diminution de l'écoulement qui se produit lorsqu'un pompage est imposéà un système aquifère qui était auparavant dans un état proche de l'équilibre dynamique. Les modèles régionaux de nappe sont en général utilisés pour calculer les prélèvements dans une procédure à deux étapes. Une solution en régime permanent donne la configuration piézométrique initiale, un jeu de conditions aux limites pour la région modélisée et les données de base pour le calcul des prélèvements. Les solutions transitoires donnent les modifications globales des conditions aux limites. Lorsque des variations saisonnières sont produites en sortie du modèle, le recours à une

  1. Seasonal Variation in the NDVI–Species Richness Relationship in a Prairie Grassland Experiment (Cedar Creek

    Directory of Open Access Journals (Sweden)

    Ran Wang

    2016-02-01

    Full Text Available Species richness generally promotes ecosystem productivity, although the shape of the relationship varies and remains the subject of debate. One reason for this uncertainty lies in the multitude of methodological approaches to sampling biodiversity and productivity, some of which can be subjective. Remote sensing offers new, objective ways of assessing productivity and biodiversity. In this study, we tested the species richness–productivity relationship using a common remote sensing index, the Normalized Difference Vegetation Index (NDVI, as a measure of productivity in experimental prairie grassland plots (Cedar Creek. Our study spanned a growing season (May to October, 2014 to evaluate dynamic changes in the NDVI–species richness relationship through time and in relation to environmental variables and phenology. We show that NDVI, which is strongly associated with vegetation percent cover and biomass, is related to biodiversity for this prairie site, but it is also strongly influenced by other factors, including canopy growth stage, short-term water stress and shifting flowering patterns. Remarkably, the NDVI-biodiversity correlation peaked at mid-season, a period of warm, dry conditions and anthesis, when NDVI reached a local minimum. These findings confirm a positive, but dynamic, productivity–diversity relationship and highlight the benefit of optical remote sensing as an objective and non-invasive tool for assessing diversity–productivity relationships.

  2. Timing of breeding and reproductive performance in murres and kittiwakes reflect mismatched seasonal prey dynamics

    Science.gov (United States)

    Shultz, M.T.; Piatt, J.F.; Harding, A.M.A.; Kettle, Arthur B.; van Pelt, Thomas I.

    2009-01-01

    Seabirds are thought to time breeding to match the seasonal peak of food availability with peak chick energetic demands, but warming ocean temperatures have altered the timing of spring events, creating the potential for mismatches. The resilience of seabird populations to climate change depends on their ability to anticipate changes in the timing and magnitude of peak food availability and 'fine-tune' efforts to match ('Anticipation Hypothesis'). The degree that inter-annual variation in seabird timing of breeding and reproductive performance represents anticipated food availability versus energetic constraints ('Constraint Hypothesis') is poorly understood. We examined the relative merits of the Constraint and Anticipation Hypotheses by testing 2 predictions of the Constraint Hypothesis: (1) seabird timing of breeding is related to food availability prior to egg laying rather than the date of peak food availability, (2) initial reproductive output (e.g. laying success, clutch size) is related to pre-lay food availability rather than anticipated chick-rearing food availability. We analyzed breeding biology data of common murres Uria aalge and black-legged kittiwakes Rissa tridactyla and 2 proxies of the seasonal dynamics of their food availability (near-shore forage fish abundance and sea-surface temperature) at 2 colonies in Lower Cook Inlet, Alaska, USA, from 1996 to 1999. Our results support the Constraint Hypothesis: (1) for both species, egg laying was later in years with warmer sea-surface temperature and lower food availability prior to egg laying, but was not related to the date of peak food availability, (2) pre-egg laying food availability explained variation in kittiwake laying success and clutch size. Murre reproductive success was best explained by food availability during chick rearing. ?? 2009 Inter-Research.

  3. Seasonal variation in the input of atmospheric selenium to northwestern Greenland snow

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Khanghyun; Hong, Sang-Bum [Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 406–840 (Korea, Republic of); Lee, Jeonghoon [Department of Science Education, Ewha womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750 (Korea, Republic of); Chung, Jiwoong; Hur, Soon-Do [Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 406–840 (Korea, Republic of); Hong, Sungmin, E-mail: smhong@inha.ac.kr [Department of Ocean Sciences, Inha University, 100 Inharo, Nam-gu, Incheon 402-751 (Korea, Republic of)

    2015-09-01

    Oxygen isotope ratio (δ{sup 18}O) and concentrations of Al, Na{sup +}, methanesulfonic acid (MSA), SO{sub 4}{sup 2−}, and selenium (Se) in a continuous series of 70 snow samples from a 3.2-m snow pit at a site in northwestern Greenland were determined using ultraclean procedures. Well-defined depth profiles of δ{sup 18}O, Al, and sea-salt-Na{sup +} allowed the determination of chronology of the snow pit that spanned approximately 6 years from spring 2003 to summer 2009. Se concentrations were at a low pg/g level, ranging from 7.2 to 45 pg/g, and exhibited high variability with generally higher values during winter and spring and lower values during summer and fall. Very high crustal enrichment factors (EF{sub c}) of Se averaging approximately 26,600 for the entire time period indicate a small contribution from crust dust. High Se/MSA ratios are generally observed in the winter and spring snow layers, in which the Se concentrations were relatively high (> 20 pg/g). This suggests that a significant component of the Se present in the snow layers is of anthropogenic origin. During the summer season, however, high EF{sub c} values are accompanied with low Se/MSA, indicating an increased contribution of marine biogenic sources. Significant correlations between Se, Al, and non-sea-salt SO{sub 4}{sup 2−} highlight that significant inputs of Se to the snow are likely controlled by the seasonality in the transport efficiency of anthropogenic Se from the source regions to the site. Based on the seasonal changes in Se concentrations, Se/MSA, and Se/S ratios observed in the samples, the input of anthropogenic Se to the site appears to be governed by the long-range transportation of Se emitted from coal combustion in East Asian countries, especially in China. - Highlights: • The first comprehensive seasonal variation of Se in Greenland snow is presented. • Data exhibit pronounced seasonality in the fallout of Se to Greenland. • High Se/MSA ratios indicate a

  4. Comparisons on seasonal and annual variations of δ18O in precipitation

    Institute of Scientific and Technical Information of China (English)

    ZHANGXinping; YAOTandong

    2004-01-01

    The spatial and temporal variations of stable oxygen isotope in precipitation on different time scales are analyzed according to the data from the IAEA/WMO stations with long survey series in the Northern Hemisphere. Temperature effect is mainly distributed in mid-high latitudes on seasonal scale except for Bamako and Addisababa stations. The δ18O /temperature slope displays the positive correlation against altitude for most of the statistical stations. Amount effect appears primarily in the region south of 30°N and coastal areas. The δ18O/precipitation slope is indirectly proportional to precipitation amount. For some of the sampling stations at mid-high latitudes where their seasonal distribution of precipitation is contrary to that of temperature, coupled with temperature effect, the amount effect appears synchronistically. Either the temperature effect or the amount effect on seasonal scale, there are positive correlations to a certain extent between the annual weighted mean δ18O and the annual mean temperature for almost all the stations. The correlation between composite δ18O and temperature on spatial scale is much more marked, compared with that of individual station. There is a good agreement between 10-year moving average temperature curves Ⅰ and Ⅱ, with the values of the former all markedly smaller than corresponding ones of the latter, calculated by the monthly mean series group Ⅰ and the annual mean series group Ⅱ, respectively. However, two calculated dδ18O/dT curves display the distinct difference: the variation amplitude of slope series Ⅱ is larger than that of slope series Ⅰ. Both curves had similar ascending trend from the 1960s to the 1970s, and then, their variations display the anti-phase. Moreover, the analyses show that there is negative correlation between slope series Ⅱ and temperature series Ⅱ. However, the status is different for slope series Ⅰ and temperature series Ⅰ. Both series have contrary trend from the

  5. Seasonal and diurnal variations of atmospheric mercury across the US determined from AMNet monitoring data

    Directory of Open Access Journals (Sweden)

    X. Lan

    2012-04-01

    Full Text Available Speciated atmospheric mercury observations collected over the period from 2008 to 2010 at the Environmental Protection Agency and National Atmospheric Deposition Program Atmospheric Mercury Network sites (AMNet were analyzed for its spatial, seasonal, and diurnal characteristics across the US Median values of gaseous elemental mercury (GEM, gaseous oxidized mercury (GOM and particulate bound mercury (PBM at 11 different AMNet sites ranged from 148–226 ppqv (1.32–2.02 ng m−3, 0.05–1.4 ppqv (0.47–12.4 pg m−3 and 0.18–1.5 ppqv (1.61–13.7 pg m−3, respectively. Common characteristics of these sites were the similar median levels of GEM as well as its seasonality, with the highest mixing ratios occurring in winter and spring and the lowest in fall. However, discernible differences in monthly average GEM were as large as 30 ppqv, which may be caused by sporadic influence from local emission sources. The largest diurnal variation amplitude of GEM occurred in the summer. Seven rural sites displayed similar GEM summer diurnal patterns, in that the lowest levels appeared in the early morning, and then the GEM mixing ratio increased after sunrise and reached its maxima at noon or in the early afternoon. However, sites in Utah (UT96, UT97 and New York (NY95 showed a distinctly different pattern, with the lowest mixing ratios appearing in the afternoon and the highest mixing ratios at night. Unlike GEM, GOM exhibited higher mixing ratios in spring and summer. The largest diurnal variation amplitude of GOM occurred in spring for most AMNet sites. GOM diurnal minima appeared before sunrise and maxima appeared in the afternoon, and the variation in magnitude for all seasons at most monitoring sites fell in the range of 0 to 2 ppqv, except the Utah sites (up to 5 ppqv. The increased GOM mixing ratio in the afternoon indicated a photochemically driven oxidation of GEM resulting in GOM formation. PBM exhibited

  6. Population dynamic of the swallowtail butterfly, Papilio polytes (Lepidoptera: Papilionidae in dry and wet seasons

    Directory of Open Access Journals (Sweden)

    SUWARNO

    2010-01-01

    Full Text Available Suwarno (2010 Population dynamic of the swallowtail butterfly, Papilio polytes (Lepidoptera: Papilionidae in dry and wet seasons. Biodiversitas 11: 19-23. The population dynamic of Papilio polytes L. (Lepidoptera: Papilionidae in dry and wet seasons was investigated in the citrus orchard in Tasek Gelugor, Pulau Pinang, Malaysia. Population of immature stages of P. polytes was observed alternate day from January to March 2006 (dry season, DS, from April to July 2006 (secondary wet season, SWS, and from October to December 2006 (primary wet season, PWS. The population dynamics of the immature stages of P. polytes varied between seasons. The immature stages of P. polytes are more abundance and significantly different in the PWS than those of the DS and the SWS. The larval densities in all seasons decreased with progressive development of the instar stages. Predators and parasitoids are the main factor in regulating the population abundance of immature stages of P. polytes. There were positive correlations between the abundance of immature stages of P. polytes and their natural enemies abundance in each season. Ooencyrtus papilioni Ashmead (Hymenoptera: Encyrtidae is the most egg parasitoid. Oxyopes quadrifasciatus L. Koch. and O. elegans L. Koch. (Araneae: Oxyopidae are the main predators in the young larvae, meanwhile Sycanus dichotomus Stal. (Heteroptera: Reduviidae, Calotes versicolor Fitzinger (Squamata: Agamidae, birds and praying mantis attacked the older larvae.

  7. Seasonal variation in basal emission rates and composition of mono- and sesquiterpenes emitted from dominant conifers in Japan

    Science.gov (United States)

    Matsunaga, Sou N.; Niwa, Shigeru; Mochizuki, Tomoki; Tani, Akira; Kusumoto, Dai; Utsumi, Yasuhiro; Enoki, Tsutomu; Hiura, Tsutom

    2013-04-01

    Biogenic volatile organic compounds (BVOCs) are known to play an important role in atmospheric chemistry due to their high reactivity and high emission rates. Therefore, in recent decades, many efforts have been made to estimate the emission rates, composition and allocation of the BVOCs. Monoterpenes (MNTs) and sesquiterpenes (SQTs) are major groups of BVOCs and mainly emitted from coniferous trees. There is quite a few reports discussing the seasonality of basal emission rate, which is a normalized emission rate at a set of standard conditions (e.g. temperature, light intensity), of the BVOCs. Three field measurements were conducted using branch enclosure techniques to determine MNTs and SQTs emission measured from mature trees of Cryptomeria japonica and Chamaecyparis obtusa, which are the most dominant trees in Japan and account for about 40-50% of Japanese forest in leaf amount throughout the four seasons in southern Japan in 2010. The results are compared with the measurements for the same compound classes obtained at a suburban area of Tokyo, Japan in 2009. The seasonal variation in the basal emissions of MNTs from both tree species at Shiiba did not show significant seasonal changes. For both tree species, the variations in the basal emission of MNTs differ in the two sites, while those of SQTs showed relatively similar variations. Chemical composition of SQTs showed clear and continued seasonal variations, while MNTs did not show any clear seasonal variation for these tree species at both sites. It can be hypothesized that the emissions of BVOC classes (e.g. MNTs and SQTs) depend on leaf age. In this paper, we discuss about the seasonal variations in the basal emission rates and chemical compositions of BVOCs obtained from the two dominant coniferous tree species in Japan based on nine field measurement campaigns conducted at two different sites.

  8. Knowing your enemies: seasonal dynamics of host social parasite recognition

    Science.gov (United States)

    D'Ettorre, Patrizia; Brunner, Elisabeth; Wenseleers, Tom; Heinze, Jürgen

    2004-12-01

    Despite its evolutionary significance, behavioural flexibility of social response has rarely been investigated in insects. We studied a host social parasite system: the slave-making ant Polyergus rufescens and its host Formica rufibarbis. Free-living host workers from parasitized and from unparasitized areas were compared in their level of aggression against the parasite and alien conspecifics. We expected that a seasonal change would occur in the acceptance threshold of F. rufibarbis workers from a parasitized area towards the parasite, whereas F. rufibarbis workers from an unparasitized area would not show substantial changes connected with the parasite’s peak in activity (raiding and colony-founding season). The results showed a significant adaptive behavioural flexibility of host species workers and are consistent with the acceptance threshold model’s (Reeve 1989) prediction that recognition systems are not fixed but context-dependent. In particular, host workers from the unparasitized area were highly aggressive towards the parasite regardless of the season, whereas host workers from the parasitized area significantly increased their aggression towards the parasite during its raiding and colony-founding season. Being able to detect and possibly kill a Polyergus scout searching for host nests can be an effective strategy for a Formica colony to avoid being raided or usurped by a parasite queen.

  9. Symmetries, variational principles, and quantum dynamics

    Directory of Open Access Journals (Sweden)

    A. Sissakian

    2004-05-01

    Full Text Available We describe the role of symmetries in formation of quantum dynamics. A quantum version of d'Alembert's principle is proposed to take into account the symmetry constrains more exact. It is argued that the time reversibility of quantum process, as the quantum analogy of d'Alembert's principle, makes the measure of the corresponding path integral δ-like. The argument of this δ-function is the sum of all classical forces of the problem under consideration plus the random force of quantum excitations. Such measure establishes the one-to-one correspondence with classical mechanics and, for this reason, allows a free choice of the useful dynamical variables. The analysis shows that choosing the action-angle variables, one may get to the free-from-divergences quantum field theory. Moreover, one can try to get an independence from necessity to extract the degrees of freedom constrained by the symmetry. These properties of new quantization scheme are vitally essential for such theories as the non-Abelian Yang-Mills gauge theory and quantum gravity.

  10. Seasonal Biophysical Dynamics of the Amazon from Space Using MODIS Vegetation Indices

    Science.gov (United States)

    Huete, A. R.; Didan, K.; Ratana, P.; Ferreira, L.

    2002-12-01

    We utilized the Terra- Moderate Resolution Imaging Spectroradiometer (MODIS) Vegetation Index (VI) products to analyze the seasonal and spatial patterns of photosynthetic vegetation activity over the Amazon Basin and surrounding regions of Brazil. The seasonal patterns of vegetation activity were studied along two, eco-climatic transects extending from (1) the cerrado region (Brasilia National Park) to the seasonal tropical forest (Tapajos National Forest) and (2) the caatinga biome to the seasonal and per-humid tropical forests. In addition to the climatic transects, we also investigated the seasonal dynamics of altered, land conversion areas associated with pastures and clearcutting land use activities. Both the normalized difference vegetation index (NDVI) and the enhanced vegetation index (EVI) at 250-m, 500-m, and 1-km were used to extract seasonal profile curves. The quality assurance (QA) information of the output products was used in noise removal and data filtering prior to the generation of the seasonal profiles. Histogram analyses were also performed at coarse (biome) scale and fine, site intensive (flux towers) scale. The seasonal patterns of the cerrado and caatinga were very pronounced with distinct dry and wet seasonal trends. We observed decreasing dry-wet seasonal patterns in the transitional areas near Araguaia National Park. In contrast, the seasonal behavior of the tropical forests were much harder to assess, but indicated slight seasonal trends that ran counter to rainfall activity. This may be attributed to new leaf growth in the dry season. We further found MODIS VI seasonal patterns to vary significantly in land converted and land degraded areas.

  11. [Diet composition and seasonal variation in feeding habits of Collichthy lucidus in Yangtze Estuary, China].

    Science.gov (United States)

    Wang, Jian-feng; Zhao, Feng; Song, Chao; Yang, Gang; Hou, Jun-li; Zhuang, Ping

    2016-01-01

    Spiny head croaker (Collichthy lucidus) is an important bottom fish distributing from the East China Sea to the Yellow Sea. In order to investigate the seasonal variation in diet composition and feeding habits, a total of 270 specimens were collected in the Yangtze Estuary from November, 2013 to August, 2014, and analyzed by using the stomach contents analysis method. The importance of different prey items was evaluated by the frequency of occurrence, abundance and mass followed by using these data to calculate the index of relative importance (IRI) and the index of preponderance (Ip) for each taxonomic category. The results showed that the diet of C. lucidus consisted of 30 species belonging to 8 orders, in which shrimps, with 38.5 IRI% and 79.1 Ip values, was the most important prey species. The followings were Mysidacea and Amphipoda. The dominant species in the diet of C. lucidus were Palaemon gravieri, Exopalaemon annandalei, E. carinicauda, Acanthomysis longirostris, A. brevirostris, Synidotea laevidorsalis and Calanus sinicus. The dominant species in the diet varied in different seasons. P. gravieri, E. annandalei and A. brevirostris were dominant species in spring and summer, A. longirostris, A. brevirostris and E. carinicauda in autumn, and P. gravieri, C. sinicus and Pesudeuphausia sinica in winter. There was 10.4% of total samples with empty stomachs, and the highest percent appeared in winter, and the lowest in autumn. The mean stomach fullness index of the whole samples was 0.6%, with the highest found in spring, the lowest in winter, indicating the feeding activity of C. lucidus varied significantly among seasons.

  12. Biodiversity and seasonal variation of benthic macrofauna in Minicoy Island, Lakshadweep, India

    Institute of Scientific and Technical Information of China (English)

    Dalia SusanV; Satheesh Kumar P; Pillai NGK

    2014-01-01

    From the Indian coast only limited data are available on the benthic fauna of the seagrass communities. In this study, seasonal variation in the distribution of macrobenthos and influence of environmental param-eters was explored at four seagrass beds and two mangrove stations along the Minicoy Island, Lakshadweep, India, from September 1999 to August 2001. A total of 160 macrobenthic species from eight major groups represented the macrofauna of the Minicoy Island. Of the identified taxa, molluscs 70 (gastropods 41.46%, bivalves 7.5%), polychaetes 27 (16.88%), crustaceans 30 (18.75%), echinoderms 11 (6.88%) and remaining others. Average seasonal abundance of benthic macrofauna ranged from 219 to 711 ind./m2, species di-versity varied from 1.45 to 3.64 bits per individual, species richness index ranged from 4.01 to 26.17, even-ness 0.69 to 1.66. In general, the higher abundance and species diversity was noticed in southern seagrass stations and northern seagrass stations, but in the mangrove stations comparatively low species diversity was observed. Three-way analysis of variance indicated that all communities resulted as being significantly different between seagrass and mangrove station, mainly when the seasonal interaction was considered. Multivariate analyses were employed to help define benthic characteristic and the relationship between environmental parameters at the six monitoring stations. Results of cluster analyses and multidimensional scale plot suggest that for mangrove region, different physiographic provinces, lower salinity, dissolved oxy-gen and sediment biotic structure have a higher influence on the species composition and diversity than other oceanographic conditions.

  13. Seasonal patterns of SST diurnal variation over the Tropical Warm Pool region

    Science.gov (United States)

    Zhang, Haifeng; Beggs, Helen; Wang, Xiao Hua; Kiss, Andrew E.; Griffin, Christopher

    2016-11-01

    Five year (2010-2014) Advanced Very High Resolution Radiometer (AVHRR) sea surface temperature (SST) data produced by the Australian Bureau of Meteorology have been validated against drifting buoy data and then used to study the seasonal patterns of the SST diurnal variation (DV) events over the Tropical Warm Pool region (TWP, 25°S-15°N, 90°E-170°E). The in situ validation results illustrate the overall good quality of the AVHRR SST data set, although an average 0.19 K underestimation of the daytime measurements has been observed. The nighttime observations are in good agreement with in situ buoys with an average bias of 0.03 and a 0.30 K standard deviation of the biases. This SST data set is then used to characterize the SST DV seasonal patterns, together with wind speeds, daily maximum solar shortwave insolation (SSImax), and latent heat flux (LHF). A double-peak seasonal pattern of SST DV is observed over the study region: the strongest DVs are found in March and October and the weakest in June. Sensitivity tests of DV to wind, SSImax, and LHF are conducted.