Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Season

  • birth season
  • breeding season
  • cold season
  • consecutive breeding season
  • consecutive growing season
  • consecutive season
  • crop season
  • cropping season
  • different season
  • dormant season
  • dry season
  • early dry season
  • early season
  • entire growing season
  • favourable season
  • field season
  • fire season
  • first growing season
  • first season
  • fishing season
  • flight season
  • flowering season
  • fly season
  • fruiting season
  • grass pollen season
  • grazing season
  • growing season
  • growth season
  • harvest season
  • hot dry season
  • hot season
  • hurricane season
  • ice-free season
  • influenza season
  • irrigation season
  • late dry season
  • late season
  • long dry season
  • longer growing season
  • mating season
  • monsoon season
  • non-breeding season
  • nonbreeding season
  • one breeding season
  • one growing season
  • one season
  • other season
  • particular season
  • pollen season
  • previous growing season
  • previous season
  • production season
  • rainy season
  • reproductive season
  • same season
  • sampling season
  • second growing season
  • second season
  • short growing season
  • snowmelt season
  • spawning season
  • spring season
  • subsequent season
  • successive growing season
  • summer rainy season
  • summer season
  • transmission season
  • warm season
  • wet season
  • winter season

  • Terms modified by Season

  • season fire
  • season length
  • season progress
  • season rainfall
  • season temperature

  • Selected Abstracts

    OC2 Seasonality Affects on Sperm Motility Kinematic Parameters of Murciano-Granadina Bucks

    D Abdelwahab
    Four Murciano-Granadina (M-G) bucks were used to study the effect of season (autumn and spring) on semen motility kinematic parameters. Ejaculates (n = 31/season) were collected twice weekly with an artificial vagina and diluted with Tris-based extender (1 : 10). Average path velocity (VAP) and linearity (LIN) were evaluated using a Computer-Assisted Semen Analysis (CASA system). A FASTCLUS procedure was applied to separate spermatozoa into subpopulations based on their motility characteristics. The mean values of both motility kinematic parameters were significantly (p < 0.05) higher in spring than in autumn. Four different motile sperm subpopulations (SP) were identified. In autumn, SP 1 (with a frequency of 17.1%) showed a VAP of 41.5 ,m/s and a LIN of 38.3%. SP 2 (37.2%) a VAP of 70.2 ,m/s and a LIN of 46.1% SP 3 (19.1%) a VAP of 93.3 ,m/s and a LIN of 31.6%. Finally, SP 4 (26.6%) a VAP of 111.8 ,m/s and a LIN of 67.2%. In spring, SP 1 (21.1%) a VAP of 46.3 ,m/s and a LIN of 50.1%. SP 2 (39.6%) a VAP of 77.0 ,m/s and a LIN of 68.6%. SP 3 (17%) a VAP of 87.8 ,m/s and a LIN of 40.2%. Finally, SP 4 (22.3%) a VAP of 112.3 ,m/s and a LIN of 70.4%. In conclusion, the season of ejaculate collection has a significant effect on sperm motility kinematic parameters of M-G bucks. [source]


    ABSTRACT The effects of variety and season on several organoleptic and nutritional quality parameters (i.e., dry weight (dw), total sugars, soluble solid compounds, titratable acidity (TA), electrical conductivity (EC), juiciness, firmness, vitamin C (vit C), total phenolic compounds, hydrophilic antioxidant capacity and minerals) of five different varieties of tomatoes (i.e., Jack, Cabrales, Jaguar, Iker and Nevada) grown in two crop cycles (spring and autumn) were studied. Each variety presented its own specific characteristics regarding the chosen parameters. Firmness, TA and EC were season dependent, whereas soluble solids content did not change between cycles. In some varieties, the dw, juiciness and total sugars were affected by climatic conditions. The total phenolic compounds and the hydrophilic antioxidant capacity were variety dependent in both cycles. By contrast, the vit C content was variety dependent only in the autumn cycle. Similarly, these latter parameters (phenolic compounds, hydrophilic antioxidant capacity and vit C) were also season dependent, showing higher values in the spring than in the autumn cycle. The effect of tomato variety and season on mineral contents is also discussed. Those tomatoes grown in the spring cycle had better quality according to the organoleptic parameters studied here as well as to a higher antioxidant capacity. The percentages of the recommended dietary allowances supplied by the studied tomatoes were not significantly affected by variety or season, despite differences in their physicochemical compositions. [source]


    ARCHAEOMETRY, Issue 4 2007
    The importance of environmental seasonality and the seasonal cycling of resources to human populations make studies of human responses to seasonality useful to test hypotheses about short- and long-term changes in human behaviour. This paper utilizes digital dental cementum luminance analysis in order to better understand patterns of the seasons of death of Ammotragus lervia at Haua Fteah, Cyrenaica, and to test whether long-term climatic changes can be detected in dental cement. The overall pattern of the season of death of A. lervia at Haua Fteah is that of year-round utilization, with a slight increase over time in A. lervia use during the growth period/summer time. The use of digital cementum luminance analysis (DCLA) to detect changes in the seasonal differences between temperatures indicates a trend for increased seasonality in temperature over the past 40 000 years at Haua Fteah. Furthermore, DCLA patterns in the more recent assemblages indicate a shift to a warmer climate from Marine Oxygen Isotope Stage (MIS) 3 to MIS 1. [source]


    ART HISTORY, Issue 3 2006
    While in London during the 1640s Wenceslaus Hollar produced a striking cycle of etchings using contemporary female figures as allegories of the seasons, followed by another series of still lifes depicting fashion accessories, in which fur muffs appear repeatedly. This article focuses on the connections between the personi-fications of winter and the still lifes, and brings out the tensions that transpire when the disinterested and supposedly objective eye utilized in Hollar's other projects of the 1640s is revealed as an eye steeped with ambivalent desires , not just in relation to the bodies of certain women, but to the commodity form as well. The fur muff in these etchings is shown to be an enigmatic entity, not only intersecting with issues related to fetishism, eroticism and urban space in early modern London, but is also poised on a threshold between different economies of the object, between residual classical and medieval systems of representation and newly emergent anxieties about the commodity and exchange value. [source]

    Seasonal and substrate preferences of fungi colonizing leaves in streams: traditional versus molecular evidence

    Liliya G. Nikolcheva
    Summary Aquatic hyphomycetes are the main fungal decomposers of plant litter in streams. We compared the importance of substrate (three leaf species, wood) and season on fungal colonization. Substrates were exposed for 12 4-week periods. After recovery, mass loss, fungal biomass and release of conidia by aquatic hyphomycetes were measured. Fungal communities were characterized by counting and identifying released conidia and by extracting and amplifying fungal DNA (ITS2), which was subdivided into phylotypes by denaturing gradient gel electrophoresis (DGGE) and terminal-restriction fragment length polymorphism (T-RFLP). Mass loss, fungal biomass and reproduction were positively correlated with stream temperature. Conidial diversity was highest between May and September. Numbers of different phylotypes were more stable. Principal coordinate analyses (PCO) and canonical analyses of principal coordinates (CAP) of presence/absence data (DGGE bands, T-RFLP peaks and conidial species) showed a clear seasonal trend (P, 0.002) but no substrate effect (P, 0.88). Season was also a significant factor when proportional similarities of conidial communities or relative intensities of DGGE bands were evaluated (P, 0.003). Substrate was a significant factor determining DGGE band intensities (P = 0.002), but did not significantly affect conidial communities (P = 0.50). Both traditional and molecular techniques suggest that strict exclusion of fungi by substrate type is rare, and that presence of different species or phylotypes is governed by season. Biomasses of the various taxa (based on DGGE band intensities) were related to substrate type. [source]

    Seasonal and management influences on bacterial community structure in an upland grassland soil

    Nabla M. Kennedy
    Abstract Floristically diverse Nardo,Galion upland grasslands are common in Ireland and the UK and are valuable in agricultural, environmental and ecological terms. Under improvement (inputs of lime, fertiliser and re-seeding), they convert to mesotrophic grassland containing very few plant species. The effects of upland grassland improvement and seasonality on soil microbial communities were investigated at an upland site. Samples were taken at five times in one year in order to observe seasonal trends, and bacterial community structure was monitored using automated ribosomal intergenic spacer analysis (ARISA), a DNA-fingerprinting approach. Differences in soil chemistry and bacterial community structure between unimproved and improved grassland soils were noted. Season was also found to cause mild fluctuations in bacterial community structure, with soil samples from colder months (October and December) more correlated with change in ribotype profiles than samples from warmer months. However, for the majority of seasons clear differences in bacterial community structures from unimproved and improved soils could be seen, indicating seasonal influences did not obscure effects associated with improvement. [source]


    ABSTRACT. Runoff generation and soil erosion were investigated at the Guadalperalón experimental watershed (western Spain), within the land-use system known as dehesa, or open, managed evergreen forests. Season and type of surface were found to control runoff and soil-loss rates. Five soil units were selected as representative of surface types found in the study area: hillslope grass, bottom grass, tree cover, sheep trails, and shrub cover. Measurements were made in various conditions with simulated rainfall to gain an idea of the annual variation in runoff and soil loss. Important seasonal differences were noted due to surface cover and moisture content of soil, but erosion rates were determined primarily by runoff. Surfaces covered with grass and shrubs always showed less erosion; surfaces covered with holm oaks showed higher runoff rates, due to the hydrophobic character of the soils. Concentrations of runoff sediment during the simulations confirmed that erosion rates at the study site depended directly on the sediment available on the soil surface. [source]

    Deep-water Archaeological Survey in the Black Sea: 2000 Season

    Cheryl Ward
    Recent archaeological survey by sidescan sonar and remotely operated vehicles (ROVs) resulted in the discovery of one of the best-preserved seagoing ships from antiquity in the anoxic waters of the Black Sea. Three shipwrecks from the 4th to 6th centuries AD, with cargoes of shipping jars from Sinop, Turkey, were found at depths of about 100 m; the fourth sits upright on the sea-bed, buried to deck level in sediment. A description of each site and identification of visible site components is followed by a discussion of directions and possible implications of future research. © 2004 The Nautical Archaeology Society [source]

    SSSR Presidential Address Rain Dances in the Dry Season: Overcoming the Religious Congruence Fallacy

    Mark Chaves
    Religious congruence refers to consistency among an individual's religious beliefs and attitudes, consistency between religious ideas and behavior, and religious ideas, identities, or schemas that are chronically salient and accessible to individuals across contexts and situations. Decades of anthropological, sociological, and psychological research establish that religious congruence is rare, but much thinking about religion presumes that it is common. The religious congruence fallacy occurs when interpretations or explanations unjustifiably presume religious congruence. [source]

    Impact of the Cropping Systems of a Minor Dry Season on the Growth, Yields and Nitrogen Uptake of Maize (Zea mays L) Grown in the Humid Tropics during the Major Rainy Season

    U. R. Sangakkara
    Abstract A field study evaluated the residual effect of a cropping system in two minor (dry) seasons on the productivity pattern and nitrogen utilization of a maize crop grown in the subsequent major (wet) seasons. The cropping systems established in the minor seasons, where evaporation exceeds rainfall, were either monocultures of maize (Zea mays L), or maize intercropped with either common bean (Phaseolus vulgaris L) or sunhemp (Crotolaria juncea L). In addition, monocultures of two green manures, namely sunhemp (Crotolaria juncea) or Tithonia (Tithonia diversifolia), were established. The residues of maize and beans and the green manures were incorporated at the end of the minor season; at the onset of rains in the major season, maize crops were established on the same plots. Germination of maize was not affected by the previous cropping system. In contrast, crop growth and yields of maize and nitrogen utilization were affected by the previous cropping system. Optimum growth and highest yields were procured in maize that was grown after a green manure crop. Similarly, although the yields were high, the planting of a green manure crop reduced nitrogen utilization by maize in the major season, thereby indicating its potential contribution to sustainability, due to its lower mining of soil nitrogen. On the basis of the results of this two-year study, the impact of cropping systems in minor seasons on the productivity of maize, a very important highland cereal in the tropics, grown under rain-fed conditions in a major season, is presented. [source]

    Season of grazing and stocking rate interactively affect fuel loads in Baikiaea plurijuga Harms woodland in northwestern Zimbabwe

    J. Gambiza
    Abstract Wildfire is a major disturbance in Baikiaea plurijuga Harms woodland savannas. We tested the hypothesis that the timing and intensity of herbivory influence fuel loads. We used three stocking rates namely light (three cows and four goats ha,1), medium (six cows and eight goats ha,1) and heavy (eleven cows and sixteen goats ha,1) and three times of grazing namely early-, middle- and late-growing seasons. Season of grazing and stocking rate influenced herbaceous phytomass. Phytomass was generally the highest (53.5 g DM m,2) in paddocks grazed during the early growing season and the lowest (27.8 g DM m,2) in those grazed during the late growing season. Phytomass was also generally the highest (40.4 g DM m,2) in lightly stocked paddocks and the lowest (32.7 g DM m,2) in heavily stocked ones. Litter mass was the lowest (160.8 g DM m,2) in paddocks grazed during the early season whereas there were no differences in ungrazed paddocks and those grazed during either mid- or late growing seasons (205.4 g DM m,2). There was a negative relationship between litter mass and stocking rate. Baikiaea Benth. woodlands should be grazed during either the mid- or late-growing season at stocking rates greater than 0.1 LU ha,1 to reduce grass fuel loads. Résumé Les feux de brousse sont une perturbation majeure dans les savanes arborées àBaikiaea plurijuga Harms. Nous avons testé l'hypothèse selon laquelle le timing et l'intensité de la consommation par les herbivores influenceraient la quantité de combustible. Nous avons utilisé trois taux de pâturage: léger (trois vaches et quatre chèvres par hectare), moyen (six vaches et huit chèvres par hectare) et élevé (11 vaches et 16 chèvres par hectare), et trois périodes de pâturage, à savoir au début, au milieu et à la fin de la période de croissance. La période de pâturage et le taux de pâturage influençaient la phytomasse herbacée. La phytomasse était généralement la plus élevée (53.5 g MS m,2) dans les enclos pâturés au début de la saison de croissance, et la plus faible (27.8 g MS m,2) dans ceux qui sont pâturés en fin de période de croissance. La phytomasse était aussi généralement la plus grande (40.4 g MS m,2) dans les enclos légèrement pâturés et la plus basse (32.7 g MS m,2) dans les enclos très pâturés. La biomasse végétale (litière) était la plus faible (160.8 g MS m,2) dans les enclos pâturés au début de la saison, alors qu'il n'y avait pas de différence entre les enclos non pâturés et ceux qui l'étaient au milieu ou à la fin de la période de croissance (205.4 g MS m,2). Il y avait une relation négative entre la masse de litière et le taux de pâturage. Les forêts àBaikiaea Benth. devraient être pâturés en milieu ou en fin de période de croissance, et à des taux plus élevés que 0.1 UFL ha,1, pour réduire la quantité de combustible herbacé. [source]

    Energy reserves during food deprivation and compensatory growth in juvenile roach: the importance of season and temperature

    P. L. M. Van Dijk
    The effect of 21 days of starvation, followed by a period of compensatory growth during refeeding, was studied in juvenile roach Rutilus rutilus during winter and summer, at 4, 20 and 27° C acclimation temperature and at a constant photoperiod (12L : 12D). Although light conditions were the same during summer and winter experiments and fish were acclimated to the same temperatures, there were significant differences in a range of variables between summer and winter. Generally winter fish were better prepared to face starvation than summer fish, especially when acclimated at a realistic cold season water temperature of 4° C. In winter, the cold acclimated fish had a two to three-fold larger relative liver size with an approximately double fractional lipid content, in comparison to summer animals at the same temperature. Their white muscle protein and glycogen concentration, but not their lipid content, were significantly higher. Season, independent of photoperiod or reproductive cycle, was therefore an important factor that determined the physiological status of the animal, and should generally be taken into account when fish are acclimated to different temperature regimes. There were no significant differences between seasons with respect to growth. Juvenile roach showed compensatory growth at all three acclimation temperatures with maximal rates of compensatory growth at 27° C. The replenishment of body energy stores, which were utilized during the starvation period, was responsible for the observed mass gain at 4° C. The contribution of the different energy resources (protein, glycogen and lipid) was dependent on acclimation temperature. In 20 and 27° C acclimated roach, the energetic needs during food deprivation were met by metabolizing white muscle energy stores. While the concentration of white muscle glycogen had decreased after the fasting period, the concentrations of white muscle lipid and protein remained more or less constant. The mobilization of protein and fat was revealed by the reduced size of the muscle after fasting, which was reflected in a decrease in condition factor. At 20° C, liver lipids and glycogen were mobilized, which caused a decrease both in the relative liver size and in the concentration of these substrates. Liver size was also decreased after fasting in the 4° C acclimated fish, but the substrate concentrations remained stable. This experimental group additionally utilized white muscle glycogen during food deprivation. Almost all measured variables were back at the control level within 7 days of refeeding. [source]

    TMAOase Activity of European Hake (Merluccius merluccius) Organs: Influence of Biological Condition and Season

    M. Rey-Mansilla
    ABSTRACT: Trimethylamine N-oxide demethylase (TMAOase) activity of several internal organs of hake were studied for 2 consecutive y. The correlation between enzymatic activity and season of year, sex, weight, and length were analyzed. While kidney and spleen showed the highest activities, liver, heart, bile, and gall bladder activities were much lower, and in some cases they were below the detection limit. A correlation between TMAOase activity of kidney and season was found. During winter and spring (February to May), the months matching the spawning peak, high activities were detected, while in summer months the activity level was lower. TMAOase activity in the rest of the organs did not seem to have a seasonal influence. Keywords: TMAOase, season, biological condition, hake, soluble protein [source]

    Seasonal changes of CLA isomers and other fatty acids of milk fat from grazing dairy herds in the Azores

    Oldemiro A Rego
    Abstract BACKGROUND: Season of the year associated with dietary changes has been recognized as a factor implicated in milk fat fatty acid (FA) profile in dairy cows. However, a lack of information exists concerning cows grazing all year round as is practiced in the Azores, where cows are supplemented in winter with maize silage plus concentrates, while in spring the higher grass allowance only requires supplementation with concentrate. The main objective of this study was to detect any seasonal variation of FA profile of milk fat from milk sampled in bulk tanks of 12 Azorean dairy herds. RESULTS Compared to winter milk, milk fat from spring presented a higher proportion of CLA cis -9,trans -11 (14.3 versus 9.6 g kg,1 FA), C18:1 trans -11 (32 versus 22 g kg,1 FA), C18:2 trans -11,cis -15 (3.7 versus 2.2 g kg,1 FA), CLA trans -11,cis -13 (0.34 versus 0.23 g kg,1 FA) and C18:3 n-3 (5.7 versus 5.4 g kg,1 FA). The C18:2 n-6/C18:3 n-3 ratio was lower (P < 0.05) in spring. Branched-chain FA, except the anteiso -C15:0, were higher in spring, while odd-chain FA (C15:0) were higher in winter. CONCLUSION: Dairy herd management in the Azores presents a seasonal variation of milk fat FA composition, where the spring milk may present increased potential benefits for human consumers. Copyright © 2008 Society of Chemical Industry [source]

    Association of Season and Pasture Grazing with Blood Hormone and Metabolite Concentrations in Horses with Presumed Pituitary Pars Intermedia Dysfunction

    N. Frank
    Background: Pituitary pars intermedia dysfunction (PPID) is a risk factor for pasture-associated laminitis, which follows a seasonal pattern. Hypothesis: Hormonal responses to season differ between PPID and unaffected horses. Animals: Seventeen horses aged 8,30 years (14 horses , 20 years of age). Methods: Longitudinal observational study. Blood was collected monthly from August 2007 until July 2008 after pasture grazing and again after overnight stall confinement. Blood hormone and metabolite concentrations were measured and pasture grass samples were analyzed to determine carbohydrate content. Analysis of variance analysis for repeated measures was performed. Results: Mean ACTH concentrations varied significantly over time (P < .001), with higher concentrations detected in August, September, and October compared with November,April. Pasture × time effects were detected for glucose and insulin concentrations, with peaks observed in September. Horses were retrospectively allocated to PPID (n = 8) and control (n = 9) groups on the basis of plasma ACTH concentrations. Changes in insulin concentrations over time differed in the PPID group when compared with the control group. Insulin concentrations were positively correlated with grass carbohydrate composition. Conclusions and Clinical Importance: PPID did not affect the timing or duration of the seasonal increase in ACTH concentrations, but higher values were detected in affected horses. Insulin concentrations differed between groups, but hyperinsulinemia was rarely detected. Glucose and insulin concentrations peaked in September when horses were grazing on pasture, which could be relevant to the seasonal pattern of laminitis. [source]

    A Season for Disarmament

    Is President Barack Obama's proposal for zero nuclear weapons realistic? Will it make the world more secure, or more prone to wars since they are no longer unthinkable? To evaluate this bold strategic initiative, we have invited comments from two former US secretaries of state, a former director of the CIA and the former head of the International Atomic Energy Agency who led the hunt for Saddam's non-existent weapons of mass destruction on the eve of the Iraq war. [source]

    Season of birth contributes to variation in university examination outcomes

    Martin Fieder
    Epidemiological studies show that birth season influences a wide range of biological parameters such as growth, reproduction, mental illnesses, dyslexia, personality, and success in school. The present study is aimed at examining birth season's relationship to examination marks achieved at a university in a very large contemporary sample of male and female undergraduate students. We find that female university students born in spring and summer achieve better marks than those born in autumn and winter. Male students born in spring receive worse marks than those born in other seasons of the year. Furthermore, we find a birth-week periodicity in examination results of female students, with highest examination results for those born in May. We suppose that biological mechanisms might explain part of the observed effects. Am. J. Hum. Biol. 18:714,717, 2006. © 2006 Wiley-Liss, Inc. [source]

    Cumulus,Oocyte Communications in the Horse: Role of the Breeding Season and of the Maturation Medium

    S Colleoni
    Contents Horse is a seasonal breeder and information on oocyte quality outside the breeding season is very limited. Ovaries obtained at the slaughterhouse are a convenient but often limited source of oocytes in this species. As the low quantity of ovaries leads to an intensive use of all available material, it would be useful to know whether ovaries collected during the non-breeding season are suitable for in vitro maturation (IVM). In an attempt to characterize the effect of season on oocyte quality, we investigated the permeability of the gap junctions (GJ) present between cumulus cells and oocytes because of their important role in oocyte growth and maturation. We also compared the effect of supplementing the maturation medium with bovine serum albumin (BSA) or oestrus mare serum (EMS). A total of 645 oocytes isolated from 158 and 154 ovaries collected during the breeding and the non-breeding season, respectively, were used in this study. Oocytes were matured for 30 h in TCM 199 supplemented either with 10% EMS or with 4 mg/ml BSA. The presence of permeable GJs between cumulus cells and oocytes was investigated with the injection of a 3% solution of the fluorescent dye Lucifer yellow into the ooplasm. No differences in efficiency of oocyte retrieval or oocyte meiotic competence were detected between oocytes collected during the breeding and non-breeding season. The vast majority (90%) of the oocytes collected during the breeding season had fully functional communications with their surrounding cumulus cells but such communications were completely interrupted in 55.3% of the oocytes collected during the non-breeding season. During the non-breeding season, the proportion of oocytes whose communications with cumulus cells were classified as closed or intermediate at the end of maturation was lower in the group matured with BSA than with EMS (71.4 vs 97.7, p < 0.05). The same trend, although not statistically significant, was observed during the breeding season also. The presence of BSA caused an incomplete cumulus expansion during both seasons. Our data indicate that oocytes collected during the non-breeding season do not show any meiotic deficiency but lack active communication with the surrounding cumulus cells at the time of their isolation from the ovary. No data are available at present for determining the consequences on the developmental competence even if data from other species suggest that this is likely. [source]

    Effects of Prescribed Fire and Season of Burn on Recruitment of the Invasive Exotic Plant, Potentilla recta, in a Semiarid Grassland

    Peter Lesica
    Abstract Prescribed fire is often used to restore grassland systems to presettlement conditions; however, fire also has the potential to facilitate the invasion of exotic plants. Managers of wildlands and nature reserves must decide whether and how to apply prescribed burning to the best advantage in the face of this dilemma. Herbicide is also used to control exotic plants, but interactions between fire and herbicides have not been well studied. Potentilla recta is an exotic plant invading Dancing Prairie Preserve in northwest Montana. We used a complete factorial design with all combinations of spring burn, fall burn, no burn, picloram herbicide, and no herbicide to determine the effects of fire, season of burn, and their interaction with herbicide on the recruitment and population growth of P. recta over a 5-year period. Recruitment of P. recta was higher in burn plots compared with controls the first year after the fire, but this did not lead to significant population growth in subsequent years, possibly due to drier than normal conditions that occurred most years of the study. Effect of season of burn was variable among years but was higher in fall compared with spring burn plots across all years. Herbicide effectively eliminated P. recta from sample plots for 3,5 years. By the end of the study density of P. recta was greater in herbicide plots that were burned than those that were not. Results suggest that prescribed fire will enhance germination of P. recta, but this will not always lead to increased population growth. Prescribed fire may reduce the long-term efficacy of herbicide applied to control P. recta and will be most beneficial at Dancing Prairie when conducted in the spring rather than the fall. Results of prescribed fire on exotic plant invasions in semiarid environments will be difficult to predict because they are strongly dependent on stochastic climatic events. [source]

    Season of Burn Influences Fire Behavior and Fuel Consumption in Restored Shortleaf Pine,Grassland Communities

    Jeffrey C. Sparks
    Abstract Pine forests of southeastern United States have been burned primarily in the dormant season to accomplish silvicultural objectives, but with increased emphasis on ecosystem restoration fires are now prescribed in other seasons. We observed fire behavior during both growing season and dormant season prescribed fires in shortleaf pine (Pinus echinata) stands managed as pine,grassland communities for the endangered Red-cockaded Woodpecker (Picoides borealis). Fuel beds for dormant season fires were characterized by lower amounts of live fuels, higher amounts of 1-hr time lag fuel and a greater total fuel load than growing season fires. Fuel consumption and percent of the total fuels consumed was greater in dormant season fires than in growing season fires. Fireline intensity, heat per unit area, reaction intensity, and rate of spread were greater in dormant season fires than in growing season fires. Lower fire intensity in growing season fires was possibly a function of lower amounts of 1-hr time lag fuels, higher amounts of live herbaceous fuels, and possibly a less porous fuel bed. Additionally, growing season fires had lower heat per unit area and reaction intensity and slower rates of spread. The Keetch-Byram drought index (KBDI) did not provide a good index for potential fire behavior on our drought-prone sandy loam soils. KBDI during growing season fires averaged over four times greater than during dormant season fires, but fire intensity was greater in dormant season fires. Low KBDI values may be misleading and give a false sense of security for dormant season fire prescriptions on sandy loam soils because the duff layer may dry more quickly as a result of inherent low water holding capacity. High KBDI values may result in prescribed burns being canceled because of conditions that are erroneously perceived to be outside the prescription window. We caution against over-reliance on KBDI as a determining factor for conducting prescribed burns on areas with sandy or sandy loam soils. [source]

    Effects of Season, Rainfall, and Hydrogeomorphic Setting on Mangrove Tree Growth in Micronesia

    BIOTROPICA, Issue 2 2007
    Ken W. Krauss
    ABSTRACT Seasonal patterns of tree growth are often related to rainfall, temperature, and relative moisture regimes. We asked whether diameter growth of mangrove trees in Micronesia, where seasonal changes are minimal, is continuous throughout a year or conforms to an annual cycle. We installed dendrometer bands on Sonneratia alba and Bruguiera gymnorrhiza trees growing naturally within mangrove swamps on the islands of Kosrae, Federated States of Micronesia (FSM), Pohnpei, FSM, and Butaritari, Republic of Kiribati, in the eastern Caroline Islands of the western Pacific Ocean. Trees were remeasured monthly or quarterly for as long as 6 yr. Annual mean individual tree basal area increments ranged from 7.0 to 79.6 cm2/yr for all S. alba trees and from 4.8 to 27.4 cm2/yr for all B. gymnorrhiza trees from Micronesian high islands. Diameter increment for S. alba on Butaritari Atoll was lower at 7.8 cm2/yr for the one year measured. Growth rates differed significantly by hydrogeomorphic zone. Riverine and interior zones maintained up to seven times the annual diameter growth rate of fringe forests, though not on Pohnpei, where basal area increments for both S. alba and B. gymnorrhiza were approximately 1.5 times greater in the fringe zone than in the interior zone. Time-series modeling indicated that there were no consistent and statistically significant annual diameter growth patterns. Although rainfall has some seasonality in some years on Kosrae and Pohnpei and overall growth of mangroves was sometimes related positively to quarterly rainfall depths, seasonal diameter growth patterns were not distinctive. A reduced chance of moisture-related stress in high-rainfall, wetland environments may serve to buffer growth of Micronesian mangroves from climatic extremes. [source]

    Nectarivory by Endemic Malagasy Fruit Bats During the Dry Season,

    BIOTROPICA, Issue 1 2006
    Daudet Andriafidison
    ABSTRACT Madagascar has a distinctive fruit bat community consisting of Pteropus rufus, Eidolon dupreanum, and Rousettus madagascariensis. In this study, we observed fruit bat visits to flowering baobabs (Adansonia suarezensis and Adansonia grandidieri) and kapok trees (Ceiba pentandra) during the austral winter. Eidolon dupreanum was recorded feeding on the nectar of baobabs and kapok, P. rufus was observed feeding on kapok only and no R. madagascariensis were seen. Three mammals species, two small lemurs (Phaner furcifer and Mirza coquereli) and E. dupreanum, made nondestructive visits to flowering A. grandidieri and are therefore all potential pollinators of this endangered baobab. This is the first evidence to show that A. grandidieri is bat-pollinated and further demonstrates the close link between fruit bats and some of Madagascar's endemic plants. Eidolon dupreanum was the only mammal species recorded visiting A. suarezensis and visits peaked at the reported times of maximum nectar concentration. Pteropus rufus visited kapok mostly before midnight when most nectar was available, but E. dupreanum visited later in the night. These differences in timing of foraging on kapok can be explained either by differing distances from the roost sites of each species or by resource partitioning. We advocate increased levels of protection, education awareness, and applied research on both mammal-pollinated baobab species and fruit bats, and suggest that both baobabs and bats are candidate "flagship species" for the threatened dry forests of Madagascar. RESUME Madagascar a une remarquable communauté de chauves-souris frugivores comprenant Pteropus rufus, Eidolon dupreanum et Rousettus madagascariensis. Dans le cadre de la présente étude, nous avons observé les visites que les chauves-souris effectuent sur les baobabs (Adansonia suarezensis et Adansonia grandidieri) et les kapokiers (Ceiba pentandra) en floraison durant l'hiver austral. Eidolon dupreanum a été observé se nourrissant du nectar des baobabs et des kapokiers, Pteropus rufus a été observé en train de se nourrir des kapokiers uniquement, et aucun Rousettus madagascariensis n'a pu être recensé. Trois espèces de mammifères, deux lémuriens (Phaner furcifer, Mirza coquereli) et Eidolon dupreanum, effectuent des visites non destructives des fleurs d' A. grandidieri et sont, de ce fait, des pollinisateurs potentiels de cette espèce de baobab en danger. Il s'agit de la première preuve qu' A. grandidieri est pollinisé par les chauves-souris. Cette observation démontre aussi le lien étroit qui existe entre les chauves-souris frugivores et quelques-unes des plantes endémiques de Madagascar. Eidolon dupreanum est la seule espèce observée sur Adansonia suarezensis et les visites sont plus fréquentes aux heures de concentration maximale de nectar. Pteropus rufus visite les kapokiers, surtout avant minuit, lorsque les nectars sont encore disponibles. En revanche, la visite effectuée par Eidolon dupreanum a lieu plus tard dans la nuit. Cette différence d'heures de fourrage sur les kapokiers pourrait être justifiée par l'inégalité de la distance des gîtes de chaque espèce ou par le partage des ressources. Aussi recommandons-nous le renforcement des mesures de protection, des activités d'IEC et de la recherche appliquée aux espèces de baobab pollinisées par des mammifères et les chauves-souris frugivores. Nous suggérons l'intégration des baobabs et des chauves-souris dans la liste des espèces " flagship" pour les forêts caducifoliées en danger à Madagascar. [source]

    Effects of Season and Successional Stage on Leaf Area Index and Spectral Vegetation Indices in Three Mesoamerican Tropical Dry Forests,

    BIOTROPICA, Issue 4 2005
    Margaret E. R. Kalacska
    ABSTRACT We compared plant area index (PAI) and canopy openness for different successional stages in three tropical dry forest sites: Chamela, Mexico; Santa Rosa, Costa Rica; and Palo Verde, Costa Rica, in the wet and dry seasons. We also compared leaf area index (LAI) for the Costa Rican sites during the wet and dry seasons. In addition, we examined differences in canopy structure to ascertain the most influential factors on PAI/LAI. Subsequently, we explored relationships between spectral vegetation indices derived from Landsat 7 ETM+ satellite imagery and PAI/LAI to create maps of PAI/LAI for the wet season for the three sites. Specific forest structure characteristics with the greatest influence on PAI/LAI varied among the sites and were linked to climatic differences. The differences in PAI/LAI and canopy openness among the sites were explained by both the past land-use history and forest management practices. For all sites, the best-fit regression model between the spectral vegetation indices and PAI/LAI was a Lorentzian Cumulative Function. Overall, this study aimed to further research linkages between PAI/LAI and remotely sensed data while exploring unique challenges posed by this ecosystem. RESUMEN En este estudio comparamos el índice de área de plantas PAI, el índice de área foliar (LAI), y la apertura de dosel para diferentes etapas sucesionales en tres sitios del bosque seco tropical: Chamela, México; Santa Rosa, Costa Rica y Palo Verde, Costa Rica en la estación lluviosa y seca. Además, examinamos las diferencias en la estructura de dosel para indagar los factores que más influyen en el PAI/LAI. En forma adicional, exploramos las relaciones entre los índices espectrales de vegetación derivados de imágenes satelitales Landsat 7 ETM+ y el PAI/LAI para así crear mapas de PAI/LAI de la estación lluviosa para los tres sitios. En este estudio encontramos que las características específicas de la estructura del bosque con mayor influencia en PAI/LAI varían entre sitios y las mismas están asociadas a diferencias climáticas. Las diferencias en el PAI/LAI y la apertura del dosel entre los sitios son explicadas tanto por el historial de uso del suelo y asi como las prácticas de manejo del bosque. Para todos los sitios el mejor modelo de regresión entre los índices espectrales de vegetación y el PAI/LAI es la función Cumulativa Lorentziana. En general, este estudio tiene como objetivo estudiar más a fondo las relaciones entre el PAI/LAI y los datos colectados de manera remota, mientras se exploran otros retos particulares que plantea este ecosistema. [source]

    Season of birth and multiple sclerosis in Sweden

    J. Salzer
    Objective,,, To estimate the risk of multiple sclerosis (MS) by month of birth in Sweden. Materials and Methods,,, Cases (n = 9361) were obtained from the Swedish MS Registry. All births in Sweden 1900,2007 served as controls (n = 12,116,853). The risk of MS was analyzed for each month of birth separately compared with birth during the other 11 months. Results,,, More (11%) cases with MS than expected were born in June. Fewer (8% and 10%) cases with MS than expected were born in December and January (non-significant after correction for multiple analyses). More (5%) cases with MS than expected were born in February,July as compared with August,January. Conclusions,,, This study supports previous results suggesting an association between the risk of MS and the season of birth. Decreased exposure to sun in the winter leading to low vitamin D levels during pregnancy is a possible explanation that needs further research. [source]

    Climatic variables are associated with seasonal acute asthma admissions to accident and emergency room facilities in Trinidad, West Indies

    M. A. Ivey
    Summary Objectives To determine if there is seasonal variation in acute asthmatic visits to accident and emergency (A&E) facilities in Trinidad and to identify the climatic variables associated with such visits. Design and methods A retrospective census of patients with asthma, defined as those who required emergency bronchodilator nebulization, was taken at two A&E facilities in Trinidad from 1 January 1997 to 31 December 1999. The study included patients aged 64 years and under. Patient demographic data were obtained from the A&E records. Climate variables were taken from the island's sole Meteorological Office. Multiple regression was used to identify climate variables that were independent predictors of A&E asthma visits. Results There were a total of 45 842 asthma admissions to the two facilities during the study period. Visits exhibited a cyclic pattern over the 3 years that varied according to the island's dry (January,May) and wet (June,December) seasons. There were more visits during the wet season than the dry (40 [SD=2] vs. 32 [SD=2] visits/day; P<0.001). The results of multiple regression indicated that season (P<0.001), barometric pressure (P<0.001), temperature difference (P<0.001), minimum temperature2 (P<0.001) and wind speed2 (P=0.032) were predictors of paediatric visits. Independent predictors of adult visits were season (P<0.001), relative humidity (P<0.001), minimum temperature (P=0.01), temperature difference2 (P<0.001) and minimum temperature2 (P=0.004). Season and climatic variables explained 18% of the variance of the total A&E asthma admissions. Conclusion There is seasonal variation in acute asthma visits to A&E facilities in Trinidad, which remains significant after controlling for climate variables. However, while climate has a role, there are other factors that may also be responsible for increased visits during the wet season. More research is needed to identify these factors. [source]

    The Arade 1 Shipwreck: Preliminary Results of the 2004 and 2005 Field Seasons

    Vanessa Loureiro
    Lost after partial destruction by dredging in 1970, Arade 1 was a priority for the Centro Nacional de Arqueologia Náutica e Subaquática (CNANS). The upper part of the hull, lying over a 7-m-long area of the bed of the Arade river, was fully observed and recorded during the first two seasons (2001 and 2002) and dismantled in a third phase (2003). The 2004 and 2005 seasons aimed at the excavation, full recording and dismantling of the lower hull, briefly observed at the end of 2002. This second, detached, portion of the hull, was buried in the sediment and corresponds to midships. © 2008 The Authors [source]

    Comparison of Gel-forming Properties of Silver Carp (Hypophthalmichthys molitrix) Surimi Prepared in Different Seasons

    C. Yuan
    ABSTRACT: The gel-forming properties of silver carp surimi made in different seasons were compared. Surimi prepared in winter and spring formed gel at 30°C, while autumn and summer surimi required a higher temperature of 40°C for gel formation. All surimi showed marked disintegration when incubated at 60°C. Ca2+ -ATPase inactivation rate of myofibrils prepared from 4 surimi samples showed that myofibrils in autumn and summer surimi were much more stable than those in winter and spring surimi by about 10°C. These results demonstrated a close relationship between the gel-forming temperature of surimi and the thermal stability of myofibrils in surimi, namely that autumn and summer surimi containing stable myofibrils required higher temperature than winter and spring surimi for the gel formation. [source]

    Epidemiologic aspects and laboratory features of enterovirus infections in Western Germany, 2000,2005

    Bernhard Roth
    Abstract From 2000 to 2005, a total of 1,096 enterovirus infections were diagnosed either by isolation of virus from cell culture or by RT-PCR (5,non-coding region (NCR)). Typing of viruses (n,=,674) was carried out by immunofluorescence with monoclonal antibodies, neutralization test or molecular methods. Seasons with high enterovirus activity were characterized by high prevalence of echovirus 30 (62.2% in 2000, 25.5% in 2001) and echovirus 13 (34.5% in 2001). In contrast, in the 2003 season, which had very low enterovirus activity, these types were rare. During this season, cell culture sensitivity (human colonic carcinoma cells and human embryonic lung fibroblasts (HEL)) was exceptionally low. In order to determine the type of "non-cultivable" enteroviruses, purified RNA from selected stool samples was subjected to direct molecular typing. VP1/2A-specific fragments were amplified by RT-PCR, cloned and sequenced. The predominant virus identified was coxsackie A. Consequently, rhabdomyosarcom cells were introduced into the daily routine, which improved the isolation of enteroviruses. Echovirus 30 was again most commonly isolated during seasons 2004 and 2005 with increasing enterovirus activity. In conclusion, high prevalence of echovirus 30 and 13 is indicative of seasons with high enterovirus activity. The type of circulating enteroviruses may influence isolation of enterovirus from cell culture. RT-PCR (VP1/2A) combined with cloning and sequencing of amplicons is a useful tool for viral typing directly from stool samples. In cases of severe enterovirus infection, virological diagnosis should not solely rely on virus isolation from cell culture. J. Med. Virol. 79:956-962, 2007. © 2007 Wiley-Liss, Inc. [source]

    Efficacy of Ovsynch Protocol with Antiprolactin Treatment for Timed Artificial Insemination During Non-breeding Seasons in Yaks (Poephagus grunniens L.)

    M Sarkar
    Contents An attempt was undertaken to investigate the efficacy of Ovsynch protocol for timed artificial insemination (TAI) with or without Norprolac (antiprolactin) treatment during non-breeding season (winter months) in yaks (n = 25). During non-breeding season, plasma prolactin profile has been reported high due to cold and nutritional stress. The Norprolac dose of i.m. administration was standardized for prolactin suppression. Three different doses viz. 2.5, 5.0 and 7.5 mg were attempted and the dose of 7.5 mg Norprolac i.m. per animal was found to be suitable for suppression of prolactin levels up to 30 h. Ovsynch treatment with Norprolac induced more number of oestrous symptoms per animal (4.8 vs 2.1), higher LH peak concentration (24.01 vs 16.16 ng/ml), longer duration of LH surge (6.8 vs 5.2 h) and higher conception rate (70 vs 30%) in Ovsynch plus Norprolac treated animals compared with animals treated with Ovsynch alone. Therefore, this study clearly indicates the opportunity for practical application of the Ovsynch plus Norprolac protocol for TAI in yaks during non-breeding seasons. [source]

    Apoptotic Changes in the Epithelium Germinativum of the Cat (Felis catus s. domestica, L. 1758) at Different Ages and Breeding Seasons

    MJ SiemieniuchArticle first published online: 25 FEB 200
    Contents Apoptosis (programmed cell death) could be considered as a physiological process that takes part in a healthy organism, which helps to maintain organism homeostasis. The visible deterioration of semen quality and the number of germ cells is accompanied by a seasonal decrease of the reproductive activity in some species. This post-effect cascade is caused by apoptosis, which is the primary mechanism responsible for the elimination of germ cells during spermatogenesis. The aim of our study was to assess apoptotic changes in the epithelium germinativum in cat testes at different ages. One hundred and two pairs of testes were obtained from domestic cats aged between 4 months and 10 years. The paraffin-embedded tissue sections were labelled using the Oncogene and Calbiochem Research Products DNA Fragmentation Detection Kit (Cat# QIA21; Darmstadt, Germany), which allows the recognition of apoptotic nuclei in tissue sections with Fragment End Labelling (FragELTM) of DNA. The activity of apoptotic processes in cat testes collected from the spring-summer period compared with the autumn-winter season revealed that, 59.42% and 51.51%, respectively, males testes were characterized by insignificant changes. The obtained data revealed a distinctive apoptotic changes in the young animal testes before spermatogenesis onset. An intensification of programmed death cells in the epithelium germinativum in the elder cats (between 3,6 and 6,10 years) was not observed. Apoptotic changes slightly intensified in cats aged between 12 and 36 months. [source]