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Summer Months (summer + month)
Selected AbstractsPost-summer heavy rainfall events in Southeast Brazil associated with South Atlantic Convergence ZoneATMOSPHERIC SCIENCE LETTERS, Issue 1 2010Kellen Carla Lima Abstract Heavy rainfall events (HREs) in the post-summer month of March in Southeast Brazil cause disasters such as floods, mudslides and landslides, mainly because the soil becomes saturated by February. Forty-five years of rainfall data show that heavy rainfall frequency increases again in the month of March. The composite anomaly fields of the atmospheric circulation during and before HREs associated with the formation of South Atlantic Convergence Zone show some special characteristics that may be used as a guide for early warning. The convergence of moisture flux in the troposphere over the region grows 40% during the 48 h before the HRE in March. Copyright © 2010 Royal Meteorological Society [source] Dental trauma that require fixation in a children's hospitalDENTAL TRAUMATOLOGY, Issue 1 2008Timothy Bruns Complex injuries to permanent teeth and their periodontium require immediate repositioning and stabilization. Many of these emergencies are treated by pediatric dental residents at the Women and Children's Hospital of Buffalo, Buffalo, New York. The purpose of this study was to characterize these complex injuries of permanent teeth that require emergency treatment in a Children's Hospital. All of the cases of dental trauma which had involved permanent teeth and which had been treated with a splint in 2001 and 2002 were reviewed. There were 79 patients that were between 5 and 19 years of age with twice as many males (54) as females (25). The number of males increased from childhood (5,10 years) to early adolescence (11,15 years) and then decreased rapidly in late adolescence (16,19 years), whereas the number of females decreased steadily with age. Most of the incidents occurred during the summer months (72%), particularly in June and July (42%), and Fridays and Saturdays were the busiest days of the week. Most of the injuries were caused by organized and recreational sporting activities (39%) and accidental falls (33%), followed by interpersonal violence (15%) and a few motor vehicle accidents (7%). The 173 permanent tooth injuries were mostly luxations (62%) or avulsions (20%), with only a few fractures of the alveolar bone (5%) or tooth root (1%). Most of the displacements were lateral luxations (40%) or extrusions (18%) with only a few intrusions (3%). These injuries most commonly afflicted the maxillary central incisors (54%), followed by the maxillary laterals (18%) and mandibular centrals (17%). The emergency treatment that was provided at the Children's Hospital included replantation and repositioning, and the placement of a semi-rigid or flexible splint. [source] Seasonal changes in abundance and age structure of burbot Lota lota (L.) and stone loach Barbatula barbatula (L.) in the littoral zone of a large pre-alpine lakeECOLOGY OF FRESHWATER FISH, Issue 1 2001N. Hofmann Abstract , Seasonal changes in the abundance and age structure of the stone loach and burbot populations in the littoral of Lake Constance, Germany were examined. The abundance of both species was lowest during the summer months and highest during autumn. The stone loach population in the littoral comprised age classes 1 to 3 plus, in autumn, age class 0. The burbot population showed distinct seasonal changes in both length and age composition. During spring and summer, only age class 1 was present in the littoral whereas, in autumn, only age class 0 was caught. This remarkably strict habitat segregation of two age classes by season is discussed with respect to a possible mechanism for avoiding conspecific predator risk in a cannibalistic species. [source] Comparison of the life history strategies of three Dysdercus true bugs (Heteroptera: Pyrrhocoridae), with special reference to their seasonal host plant useENTOMOLOGICAL SCIENCE, Issue 4 2005Katsuyuki KOHNO Abstract The life history strategy and seasonal host plant use of three Dysdercus bugs (D. cingulatus, D. poecilus and D. decussatus) were compared based on 2 years of twice monthly observations on Ishigaki-jima Island (24°N, 124°E) in the southernmost part of Japan. Dysdercus poecilus reproduced almost year round, exclusively on Sida rhombifolia, which bears fruit and/or seeds almost year round. Dysdercus cingulatus reproduced successively on various malvaceous and bombacaceous plant species, according to their seasonal fruiting cycles. Its robust reproduction was observed on Hibiscus makinoi during winter months and on Chorisia speciosa and Bombax ceiba in early summer, whereas small-scale reproduction was observed on various malvaceous plant species during the summer and autumn months. Dysdercus decussatus reproduced on Hibiscus tiliaceus and Thespesia populnea during the summer months, when these host plants bear abundant fruit and/or seeds, and its adults formed conspicuous aggregations without copulation on the underside of the leaves of those plants from November to the subsequent May. Each Dysdercus species showed a species-specific life history strategy according to the differences in the phenology of their host plants. [source] First report of saxitoxin in Finnish lakes and possible associated effects on human healthENVIRONMENTAL TOXICOLOGY, Issue 3 2005Jarkko Rapala Abstract This study is the first report of saxitoxin in cyanobacterial blooms in Finland. Bloom samples (n = 50) were collected from Finnish freshwater sites during summer months of 2002 and 2003. These samples were screened for the presence of paralytic shellfish toxins (PSTs) using the Jellett rapid PSP screening test. Samples testing positive for PSTs (n = 7) were further analyzed with saxiphilin- and voltage-gated sodium channel [3H]-STX,binding radioreceptor assays and liquid chromatography using fluorescence and mass spectrometric analysis. The results indicated that saxitoxin (STX) was the only PST analogue in the samples and that it was present in high concentrations, as much as 1 mg L,1. Microscopic analysis revealed that 95%,100% of the phytoplankton in the positive samples consisted of Anabaena lemmermannii. The trophic status of lakes in which STX-containing blooms were found varied from oligotrophic to hypertrophic. All the lakes had high nitrogen-to-phosphorus ratios. In some instances, samples had been collected from sites where swimmers had reported adverse health effects, and in three such cases, reported adverse health effects were associated with sites from which samples testing positive for STX had been received. Symptoms of fever, eye irritation, abdominal pains, and skin rash were reported in children aged 2,10 years after exposure to the water. These were not the adverse human symptoms typical of STX poisoning; rather, they represented acute effects often reported following recreational exposure to cyanobacterial blooms. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 331,340, 2005 [source] Modeling monthly temperature data in Lisbon and PragueENVIRONMETRICS, Issue 7 2009Teresa Alpuim Abstract This paper examines monthly average temperature series in two widely separated European cities, Lisbon (1856,1999) and Prague (1841,2000). The statistical methodology used begins by fitting a straight line to the temperature measurements in each month of the year. Hence, the 12 intercepts describe the seasonal variation of temperature and the 12 slopes correspond to the rise in temperature in each month of the year. Both cities show large variations in the monthly slopes. In view of this, an overall model is constructed to integrate the data of each city. Sine/cosine waves were included as independent variables to describe the seasonal pattern of temperature, and sine/cosine waves multiplied by time were used to describe the increase in temperature corresponding to the different months. The model also takes into account the autoregressive, AR(1), structure that was found in the residuals. A test of the significance of the variables that describe the variation of the increase in temperature shows that both Lisbon and Prague had an increase in temperature that is different according to the month. The winter months show a higher increase than the summer months. Copyright © 2009 John Wiley & Sons, Ltd. [source] Schooling and migration of large pelagic fishes relative to environmental cuesFISHERIES OCEANOGRAPHY, Issue 2 2000Robert Humston A kinesis model driven by high-resolution sea surface temperature maps is used to simulate Atlantic bluefin tuna movements in the Gulf of Maine during summer months. Simulations showed that individuals concentrated in areas of thermal preference. Results are compared to empirical distribution maps of bluefin tuna schools determined from aerial overflights of the stock during the same time periods. Simulations and empirical observations showed similar bluefin tuna distributions along fronts, although interannual variations in temperature ranges occupied suggest that additional foraging factors are involved. Performance of the model is further tested by simulating the relatively large-scale annual north,south migrations of bluefin tuna that followed a preferred thermal regime. Despite the model's relatively simple structure, results suggest that kinesis is an effective mechanism for describing movements of large pelagic fish in the expansive ocean environment. [source] Stocking piscivores to improve fishing and water clarity: a synthesis of the Lake Mendota biomanipulation projectFRESHWATER BIOLOGY, Issue 12 2002R. C. Lathrop SUMMARYY 1.,A total of 2.7 × 106 walleye fingerlings and 1.7 × 105 northern pike fingerlings were stocked during 1987,99 in eutrophic Lake Mendota. The objectives of the biomanipulation were to improve sport fishing and to increase piscivory to levels that would reduce planktivore biomass, increase Daphnia grazing and ultimately reduce algal densities in the lake. The combined biomass of the two piscivore species in the lake increased rapidly from < 1 kg ha,1 and stabilised at 4,6 kg ha,1 throughout the evaluation period. 2.,Restrictive harvest regulations (i.e. increase in minimum size limit and reduction in bag limit) were implemented in 1988 to protect the stocked piscivores. Further restrictions were added in 1991 and 1996 for walleye and northern pike, respectively. These restrictions were essential because fishing pressure on both species (especially walleye) increased dramatically during biomanipulation. 3.,Commencing in 1987 with a massive natural die-off of cisco and declining yellow perch populations, total planktivore biomass dropped from about 300,600 kg ha,1 prior to the die-off and the fish stocking, to about 20,40 kg ha,1 in subsequent years. These low planktivore biomasses lasted until a resurgence in the perch population in 1999. 4.,During the period prior to biomanipulation when cisco were very abundant, the dominant Daphnia species was the smaller-bodied D. galeata mendotae, which usually reached a biomass maximum in June and then crashed shortly thereafter. Beginning in 1988, the larger-bodied D. pulicaria dominated, with relatively high biomasses occurring earlier in the spring and lasting well past mid-summer of many years. 5.,In many years dominated by D. pulicaria, Secchi disc readings were greater during the spring and summer months when compared with years dominated by D. galeata mendotae. During the biomanipulation evaluation period, phosphorus (P) levels also changed dramatically thus complicating our analysis. Earlier research on Lake Mendota had shown that Daphnia grazing increased summer Secchi disc readings, but P concentrations linked to agricultural and urban runoff and to climate-controlled internal mixing processes were also important factors affecting summer readings. 6.,The Lake Mendota biomanipulation project has been a success given that high densities of the large-bodied D. pulicaria have continued to dominate for over a decade, and the diversity of fishing opportunities have improved for walleye, northern pike and, more recently, yellow perch. 7.,Massive stocking coupled with very restrictive fishing regulations produced moderate increases in piscivore densities. Larger increases could be realised by more drastic restrictions on sport fishing, but these regulations would be very controversial to anglers. 8.,If the lake's food web remains in a favourable biomanipulation state (i.e. high herbivory), further improvements in water clarity are possible with future reductions in P loadings from a recently initiated non-point pollution abatement programme in the lake's drainage basin. [source] Palaeoeskimo site burial by solifluction: Periglacial geoarchaeology of the tayara site (KbFk-7), Qikirtaq Island, Nunavik (Canada)GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 2 2008Dominique Todisco The geoarchaeological study of the Palaeoeskimo Tayara site on Qikirtaq Island (Nunavik) has led to a better understanding of archaeological site formation in the arctic periglacial environment. The surrounding geomorphology (extra-site) is characterized by fine-grained, low plastic and leached postglacial glaciomarine sediments that have been reworked by sheet-like solifluction. This process buried the northern part of the Tayara site with mean annual rates between 1.68 and 2.86 cm/yr over approximately 350 years (1330,980 yr B.P.). The physicochemical and mineralogical properties of the frost-susceptible glaciomarine sediments may explain their susceptibility to solifluction. This process was probably enhanced by longer thawing periods or warmer/moister summer months that induced active layer thickening or rapid soil thawing. The dates we obtained in the downstream valley show that solifluction occurred during short warm periods in the Late Holocene between ca. 1500 and 1000 yr B.P., after 1000 yr B.P. (or after 500 yr B.P.) and recently (90,60 yr B.P.). Our data provide insights on the site factors and climate factors that govern site burial by solifluction. Solifluction promoted the preservation of the three superposed archaeological levels in the Tayara site; however, the waterlogging of the site related to solifluction also likely caused the subsequent abandonment of the site by the Palaeoeskimo people. © 2008 Wiley Periodicals, Inc. [source] Climate change and bet-hedging: interactions between increased soil temperatures and seed bank persistenceGLOBAL CHANGE BIOLOGY, Issue 10 2009MARK K. J. OOI Abstract In order to predict the long-term consequences of climate change, it is necessary to link future environmental changes to mechanisms that control plant population processes. This information can then be incorporated into strategies to more accurately model climate change impacts on species or to estimate future extinction risks. We examined the impact of increased temperatures on the longevity and dynamics of the persistent soil seed banks of eight ephemeral species from arid Australia. We found that the predicted global temperature increases under climate change will be reflected in increased soil temperatures, and that seeds in the soil seed bank will be exposed to long durations of high temperatures over the summer months. Three of the eight species studied had significantly greater levels of germination after exposure to predicted increased soil temperatures. Another species displayed a dramatic decrease in seed viability after such exposure. The capacity of such species to use the seed bank to bet hedge against rainfall events that cause germination but are insufficient to allow plant maturation, is compromised by increased germinability and subsequent loss or reduction of seed bank persistence. These predicted changes in the dynamics of soil seed banks increase the risk of local extinctions of these species, while the composition of the community may be altered by changes in species abundance. Our results show that the risk spreading mechanism provided by persistent seed banks could be compromised by the mechanistic impact of forecast temperature increases in arid habitats, and highlight the need to understand mechanisms that control population dynamics when attempting to address likely future impacts of climate change on biodiversity. [source] Detrimental effects of recent ocean surface warming on growth condition of Atlantic salmonGLOBAL CHANGE BIOLOGY, Issue 5 2008CHRISTOPHER D. TODD Abstract Ocean climate impacts on survivorship and growth of Atlantic salmon are complex, but still poorly understood. Stock abundances have declined over the past three decades and 1992,2006 has seen widespread sea surface temperature (SST) warming of the NE Atlantic, including the foraging areas exploited by salmon of southern European origin. Salmon cease feeding on return migration, and here we express the final growth condition of year-classes of one-sea winter adults at, or just before, freshwater re-entry as the predicted weight at standard length. Two independent 14-year time series for a single river stock and for mixed, multiple stocks revealed almost identical temporal patterns in growth condition variation, and an overall trend decrease of 11,14% over the past decade. Growth condition has fallen as SST anomaly has risen, and for each year-class the midwinter (January) SST anomalies they experienced at sea correlated negatively with their final condition on migratory return during the subsequent summer months. Stored lipids are crucial for survival and for the prespawning provisioning of eggs in freshwater, and we show that under-weight individuals have disproportionately low reserves. The poorest condition fish (,30% under-weight) returned with lipid stores reduced by ,80%. This study concurs with previous analyses of other North Atlantic top consumers (e.g. somatic condition of tuna, reproductive failure of seabirds) showing evidence of major, recent climate-driven changes in the eastern North Atlantic pelagic ecosystem, and the likely importance of bottom-up control processes. Because salmon abundances presently remain at historical lows, fecundity of recent year-classes will have been increasingly compromised. Measures of year-class growth condition should therefore be incorporated in the analysis and setting of numerical spawning escapements for threatened stocks, and conservation limits should be revised upwards conservatively during periods of excessive ocean climate warming. [source] Effects of ultraviolet radiation on litter decomposition depend on precipitation and litter chemistry in a shortgrass steppe ecosystemGLOBAL CHANGE BIOLOGY, Issue 10 2007LESLIE A. BRANDT Abstract We examined the effect of altered levels of ultraviolet (UV) radiation (280,400 nm) and different amounts of precipitation on the decomposition rates of litter of contrasting carbon to nitrogen ratio (C : N) in a 3-year field experiment in a shortgrass steppe (SGS) ecosystem. UV radiation was either blocked or passed under clear plastic tents where precipitation was applied to simulate a very dry or very wet year. These treatments minimized or maximized the abiotic component (UV) or the biotic component (biological activity of decomposer organisms) of decomposition to assess potential interactions between the two. Initial litter chemistry varied in response to having been grown under ambient or elevated atmospheric CO2 concentrations. While precipitation and litter chemistry were the most important drivers in decomposition in this system, UV radiation increased decomposition rates under dry conditions in litter with higher C : N ratios. Exposure to UV radiation slightly increased the amount of holocellulose that was lost from the litter. UV exposure did not affect the decomposition of the lignin fraction. Increased decomposition with UV radiation was accompanied by a decrease in N immobilization over the summer months. These results suggest that the effects of UV radiation on decomposition rates may be primarily abiotic, caused by direct photochemical degradation of the litter. Our results demonstrate that the role of UV radiation in litter decomposition in semiarid systems depends on the aridity of the system and the chemistry of the litter. [source] Effects of wildfire and permafrost on soil organic matter and soil climate in interior AlaskaGLOBAL CHANGE BIOLOGY, Issue 12 2006JENNIFER W. HARDEN Abstract The influence of discontinuous permafrost on ground-fuel storage, combustion losses, and postfire soil climates was examined after a wildfire near Delta Junction, AK in July 1999. At this site, we sampled soils from a four-way site comparison of burning (burned and unburned) and permafrost (permafrost and nonpermafrost). Soil organic layers (which comprise ground-fuel storage) were thicker in permafrost than nonpermafrost soils both in burned and unburned sites. While we expected fire severity to be greater in the drier site (without permafrost), combustion losses were not significantly different between the two burned sites. Overall, permafrost and burning had significant effects on physical soil variables. Most notably, unburned permafrost sites with the thickest organic mats consistently had the coldest temperatures and wettest mineral soil, while soils in the burned nonpermafrost sites were warmer and drier than the other soils. For every centimeter of organic mat thickness, temperature at 5 cm depth was about 0.5°C cooler during summer months. We propose that organic soil layers determine to a large extent the physical and thermal setting for variations in vegetation, decomposition, and carbon balance across these landscapes. In particular, the deep organic layers maintain the legacies of thermal and nutrient cycling governed by fire and revegetation. We further propose that the thermal influence of deep organic soil layers may be an underlying mechanism responsible for large regional patterns of burning and regrowth, detected in fractal analyses of burn frequency and area. Thus, fractal geometry can potentially be used to analyze changes in state of these fire prone systems. [source] Water resources in mountain regions: a methodological approach to assess the water balance in a highland-lowland-systemHYDROLOGICAL PROCESSES, Issue 5 2007Rolf Weingartner Abstract Mountains and highlands are typically areas that provide considerable quantities of water, the latter being an important resource for the lowlands. These run-off quantities remain discernible in the superior-scale river systems and significantly contribute to the global water resources. Therefore, mountain regions ought to be given specific consideration with regard to management endeavours. Although well known in principle, details of water resources originating from mountains remain under discussion. A new approach has been introduced, which depicts the water balance of Switzerland in a spatially distributed manner, based on catchments of about 150 km2. The main feature of this approach is the areal precipitation, which is calculated using run-off, evaporation and storage change of glaciers, instead of being derived from gauged precipitation values. This methodology was selected because measurement and regionalization of precipitation remain subject to large uncertainties in mountainous areas. Subsequently, the view is widened to the European Alps, which, as compared with the surrounding lowlands, contribute considerably higher annual discharge, especially in the summer months. Finally, the focus is put on the hydrological significance of mountains in general. In dry regions, mountains, in particular, are indispensable contributors to the water resources downstream. Copyright © 2006 John Wiley & Sons, Ltd. [source] Characterization of surface storage and runoff patterns following peatland restoration, Quebec, CanadaHYDROLOGICAL PROCESSES, Issue 18 2006M. A. Shantz Abstract Blocking drainage ditches and creating bunds to limit surface water losses are important for restoring abandoned peat-extraction sites in North America. However, these runoff control techniques have not been well characterized, particularly during the snowmelt period. Therefore, patterns of runoff timing and magnitude were evaluated in a peatland (Bois-des-Bel, Quebec, Canada) undergoing restoration (restored site), in comparison with an unrestored section of the same peatland (unrestored site). Snowmelt dominated runoff, representing over 79% of the April to August runoff for both sites in 2001. Low (25,35 cm) bunds constructed on the restored site detained water for much of the melt period, but some water loss occurred where bunds were breached. Overland flow and surface ponding were prevalent at the restored site, but were not evident at the unrestored site. At the restored site, the presence of bunds and frozen, saturated (thus impermeable) ground contributed to differences in snowmelt runoff patterns relative to the unrestored site. In the post-snowmelt period (May,August 2001 and 2002), restored site runoff was reduced to 25% of that lost at the unrestored site. Both hydrometric and chemical hydrograph separation analysis using electrical conductivity indicated that blocked ditches restricted water losses from much of the restored site during the summer months, when the bunds had little effect on runoff. However, discharge peaks were greater at the restored site relative to the unrestored site and generally occurred more quickly following rainfall, because of the wetter antecedent conditions. Copyright © 2006 John Wiley & Sons, Ltd. [source] The influence of diurnal temperatures on the hydrochemistry of a tufa-depositing streamHYDROLOGICAL PROCESSES, Issue 17 2003R. Drysdale Abstract At-a-station diurnal variations in carbonate hydrochemistry were measured during four observation periods at Davys Creek, a tufa-depositing stream in central NSW, Australia. Major ion concentrations and continuously logged measurements of specific conductivity, pH and temperature showed that changes in the amount of CaCO3 deposited upstream of the study reach were directly related to changes in diurnal water temperatures, which control the rate of CO2 efflux to the atmosphere. The greatest upstream losses occurred during the mid-afternoon water temperature peak, whereas the lowest upstream losses occurred at sunrise, when water temperatures were at their lowest. Cloudy days at all times of the year produced small diurnal water temperatures ranges (c. 2,5°C) and, consequently, relatively small changes in upstream CaCO3 loss (23,50 mg L,1) through the day. Clear sunny days, especially during summer months, produced large diurnal water temperature changes (up to c. 11°C), which in turn triggered diurnal changes in upstream CaCO3 loss of up to 100 mg L,1. By implication, the active reach of tufa deposition must advance downstream and increase in length during the evening and vice versa during the day. Given that the temperature of Davys Creek waters are a function of insolation, changes in the reach of tufa deposition under baseflow conditions are a direct function of the prevailing weather. This has implications for the palaeoclimatic interpretation of fossil tufa deposits. Copyright © 2003 John Wiley & Sons, Ltd. [source] Impact of an extreme melt event on the runoff and hydrology of a high Arctic glacierHYDROLOGICAL PROCESSES, Issue 6 2003Sarah Boon Abstract On 28,30 July 2000, an extreme melt event was observed at John Evans Glacier (JEG), Ellesmere Island (79° 40,N, 74° 00,W). Hourly melt rates during this event fell in the upper 4% of the distribution of melt rates observed at the site during the period 1996,2000. Synoptic conditions during the event resulted in strong east-to-west flow over the northern sector of the Greenland Ice Sheet, with descending flow on the northwest side reaching Ellesmere Island. On JEG, wind speeds during the event averaged 8·1 m s,1 at 1183 m a.s.l., with hourly mean wind speeds peaking at 11·6 m s,1. Air temperatures reached 8°C, and rates of surface lowering measured by an ultrasonic depth gauge averaged 56 mm day,1. Calculations with an energy balance model suggest that increased turbulent fluxes contributed to melt enhancement at all elevations on the glacier, while snow albedo feedback resulted in increased melting due to net radiation at higher elevations. The event was responsible for 30% of total summer melt at 1183 m a.s.l. and 15% at 850 m a.s.l. Conditions similar to those during the event occurred on only 0·1% of days in the period 1948,2000, but 61% of events occurred in the summer months and there was an apparent clustering of events in the 1950s and 1980s. Such events have the potential to impact significantly on runoff, mass balance and drainage system development at high Arctic glaciers, and changes in their incidence could play a role in determining how high Arctic glaciers respond to climate change and variability. Copyright © 2003 John Wiley & Sons, Ltd. [source] The zone of vegetation influence on baseflow revealed by diel patterns of streamflow and vegetation water use in a headwater basinHYDROLOGICAL PROCESSES, Issue 8 2002Barbara J. Bond Water use by vegetation can be closely linked to streamflow patterns on a variety of time scales. However, many of the details of these linkages are poorly understood. We compared diel (24 h) patterns of transpirational water use with streamflow patterns in a small headwater basin that displays a marked diel variation during summer months. The study site was in western Oregon. Our objectives were to: (1) determine the phase shift, i.e. the time lag between maximum transpiration and minimum streamflow, and the strength of the correlation at that time lag; (2) determine the amount of streamflow that is ,missing' during each diel cycle (i.e. the difference between base flow, defined by the daily maxima, and actual flow) and use it to estimate the zone, or area, of vegetation that influences daily streamflow patterns; (3) test and refine a conceptual model of how the coupling between vegetation water use and streamflow changes over the period of summer drought in this basin. We found that vegetation water use in the summer is coupled to streamflow over time scales of 4 to 8 h, and water-use-related fluctuations accounted for 1 to 6% of summer base flow. Direct evaporation from the channel was an order of magnitude less than the diel streamflow decrease. Transpiration within only 0·1 to 0·3% of the basin area accounted for the diel variation in streamflow. As the basin drained further through the summer, the coupling between vegetation and streamflow was diminished and occurred at longer time scales, and the zone of vegetation influence became smaller. This pattern is in accordance with our conceptual model, which attributes the summer decline in the strength of the vegetation,streamflow coupling to the increasing depth of plant-available water in the soil profile. Although this study is preliminary, we believe it is an important first step in describing better the coupling of vegetation water use to streamflow. Copyright © 2002 John Wiley & Sons, Ltd. [source] Minor and trace element export from a glacierized Alpine headwater catchment (Haut Glacier d'Arolla, Switzerland)HYDROLOGICAL PROCESSES, Issue 18 2001Andrew Mitchell Abstract Major ion concentrations in meltwaters draining glacial environments have been widely reported. However, concentrations of minor and trace elements have received scant attention. This study presents trace and minor element variations in bulk meltwaters draining Haut Glacier d'Arolla (Switzerland) based on twice-daily sampling throughout the 1999 ablation season, which represents the most detailed meltwater quality dataset to date. In order to assess the mode of export from the catchment, these elements are partitioned into (i) ,dissolved' and (ii) ,particulate-associated' minor and trace element components. A computer-based speciation model (PHREEQCi) was applied to the bulk meltwater data, suggesting that Ba, Be, Cd, Cu, Li, Rb and Sr exist primarily as mobile monovalent or divalent dissolved cations, which may be involved in interactions with suspended sediment surfaces. Conversely, the model predicts the precipitation of Fe, Al, Mn and Cr (oxi)hydroxides, suggesting these species may be predominantly transported as colloids, which may remove other minor and trace elements from solution by co-precipitation reactions. Laboratory leaching experiments on suspended sediments and fresh rock powder suggests that minor and trace element concentrations may also be influenced by (oxy)hydroxide precipitation and adsorption,desorption reactions with suspended sediment surfaces. The quantity and transport mode of trace and minor elements may influence their bioavailability downstream of glacierized headwater catchments. Further, the enrichment of many dissolved minor and trace elements in meltwaters compared with world stream-waters, coupled with the timing of water and sediment delivery during the summer months, may have implications for downstream aquatic environments. Copyright © 2001 John Wiley & Sons, Ltd. [source] Avian influenza surveillance in wild birds in the European Union in 2006INFLUENZA AND OTHER RESPIRATORY VIRUSES, Issue 1 2009Uta Hesterberg Abstract Background, Infections of wild birds with highly pathogenic avian influenza (AI) subtype H5N1 virus were reported for the first time in the European Union in 2006. Objectives, To capture epidemiological information on H5N1 HPAI in wild bird populations through large-scale surveillance and extensive data collection. Methods, Records were analysed at bird level to explore the epidemiology of AI with regard to species of wild birds involved, timing and location of infections as well as the applicability of different surveillance types for the detection of infections. Results, In total, 120,706 records of birds were sent to the Community Reference Laboratory for analysis. Incidents of H5N1 HPAI in wild birds were detected in 14 EU Member States during 2006. All of these incidents occurred between February and May, with the exception of two single cases during the summer months in Germany and Spain. Conclusions, For the detection of H5N1 HPAI virus, passive surveillance of dead or diseased birds appeared the most effective approach, whilst active surveillance offered better detection of low pathogenic avian influenza (LPAI) viruses. No carrier species for H5N1 HPAI virus could be identified and almost all birds infected with H5N1 HPAI virus were either dead or showed clinical signs. A very large number of Mallards (Anas platyrhynchos) were tested in 2006 and while a high proportion of LPAI infections were found in this species, H5N1 HPAI virus was rarely identified in these birds. Orders of species that appeared to be very clinically susceptible to H5N1 HPAI virus were swans, diving ducks, mergansers and grebes, supporting experimental evidence. Surveillance results indicate that H5N1 HPAI virus did not establish itself successfully in the EU wild bird population in 2006. [source] Air temperature impacts over Eastern North America and Europe associated with low-frequency North Atlantic SST variabilityINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 1 2009Anthony Arguez Abstract Air temperature anomalies over eastern North America and Europe are analysed during the extreme phases of the two leading low-frequency modes of North Atlantic sea surface temperature (SST) during the 1906,2005 period. The leading mode of SST is a multi-decadal signal,commonly referred to as the Atlantic multi-decadal oscillation,with uniform polarity over the North Atlantic. Air temperature anomalies over the eastern United States and Northern Europe during extreme phases of this mode are of the same sign as the corresponding SST anomalies. The most intense air temperature impacts occur in summer months. The second mode exhibits considerable spectral energy in the quasi-decadal (,12 year) range. The spatial signature and associated air temperature anomalies of mode 2 are strongly correlated with both SST and land temperature impacts of the North Atlantic Oscillation (NAO). Copyright © 2008 Royal Meteorological Society [source] Temperature trends in Switzerland and Europe: implications for climate normalsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 5 2006Simon C. Scherrer Abstract This study discusses problems of the concept of normal period,based anomalies arising from climate variability and ongoing climate change. The widely used WMO 1961,1990 (61,90) standard normal period is compared to other consecutive 30-year normal periods in detail. Focus is given to the temperature distribution in Switzerland and on the European continent. In these regions, the temperature trend of the last decades led to an unusually high number of months with positive temperature anomalies relative to the WMO 61,90 standard normal period. Swiss anomalies based on the 61,90 normal are up to 1.25 K higher than those based on the Latest 30-years Running Normal (LRN). The probability to observe a positive temperature anomaly with respect to the 61,90 normal increased from 50% to near 80% for certain months of the year. Compared to the LRN, this change is statistically significant for 7 out of the 12 months on the 95% level. The strongest signal can be found for the summer months, whereas temperatures in fall do not show any trends. Similar results are found for more than 90% of the European continental area. For most regions, 2,5 are statistically inconsistent with the 61,90 distribution. For southern France, parts of Spain and southern Scandinavia even 7,9 months are inconsistent. Copyright © 2005 Royal Meteorological Society. [source] Evaluation of the North Atlantic SST forcing on the European and Northern African winter climateINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2006Belén Rodríguez-Fonseca Abstract The 1960,1996 patterns of monthly anomalous winter precipitation in Europe and North Africa (ENA) and their connection with the North Atlantic SST are studied. A lag Singular Value Decomposition analysis has been applied to monthly SST and precipitation data to define the most influential Atlantic oceanic areas on the winter ENA rainfall. The results indicate a link between the subtropical North Atlantic SST and the winter precipitation anomalies in areas of the northern,southwestern Europe and northern Africa, since the preceding summer months. We also show that the SLP pattern connected with this subtropical oceanic area is not the NAO itself, and we explain this subtropical,extratropical connection through changes in the trade winds. The estimates of ENA winter precipitation anomalies, based on the previous summer SST, have been validated using a bootstrap analysis. Finally, we verify the reliability of this connection for the whole period from 1900 to 1996. Copyright © 2006 Royal Meteorological Society. [source] The climatology of sea breezes on SardiniaINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2002M. Furberg Abstract Hourly wind speed and direction data from 12 coastline stations on Sardinia, Italy, are analysed in order to characterize sea breezes in the region. A set of criteria based on the diurnal reversal of wind direction, and the thermal gradient necessary to drive the circulation, is used to identify sea breeze days. Statistics are presented that describe the occurrence, duration, and strength of the sea breezes. On a stationwide basis, sea breezes are most frequent in the summer months (May,August), when they appear on more than one-third of the days. Sea breeze occurrence and duration are the greatest for the stations on the east coast of the island. The all-station average sea breeze duration reaches a maximum of about 9 h in June. The strength of the sea breezes is roughly 3 m s,1 during summer months on average over all stations in the sample. An analysis of mean daily hodographs for the stations in the sample shows clearly the onshore,offshore nature of the sea breeze circulation, and the response of the sea breezes to the local coastline. Sea breezes are shown to develop simultaneously on all coasts of the island under appropriate synoptic conditions. Copyright © 2002 Royal Meteorological Society. [source] Demographic features and seasonal variations in patients with acne vulgaris in Saudi Arabia: a hospital-based studyINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 12 2002Ali M. Al-Ameer MD Aim To review the demographic features and seasonal variations of acne vulgaris in patients diagnosed at the Dermatology Outpatient Clinic, King Fahad Hospital of the University (KFHU), Al-Khobar, Saudi Arabia. Methods Two hundred and twenty cases (142 females, 78 males; mean age, 14.8 and 16.3 years, respectively) seen between January 1, 1999 and December 31, 2000 were studied. Results Patients suffering from acne vulgaris made up 19.6% of the new cases seen at the clinic. The male to female ratio was 1 : 1.8. The mean age of onset was 16.3 ± 2.1 years for males and 14.8 ± 3.9 years for females (P = 0.003). The largest numbers of patients were seen during the cold months of the year (November to February). Conclusions Acne vulgaris constituted nearly one fifth of all visits to the dermatologist with female predominance. It appears nearly one and a half years earlier in females than in males. Seasonal variations were observed in acne as the condition exacerbates in winter, while if often improves during the summer months. [source] A unique variant of Darier's diseaseINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 4 2001Christopher M. Peterson MD A 45-year-old black woman presented with a chief complaint of an increasing number of ,,light spots'' on her face, upper trunk, and legs. She had a 4-year history of a pruritic eruption on the dorsum of her hands. The eruption was particularly pruritic in the summer months. Other family members, including her sister and her daughters, reportedly had a similar dermatologic problem. The patient had been previously evaluated and biopsied by another dermatologist. The earlier biopsy was nondiagnostic, however, and she presented for further evaluation of this problem. On physical examination, the patient had hypopigmented macules along her jawline (Fig. 1), lateral neck, and upper chest. She had similar hypopigmented macules on her thighs. She had hyperkeratosis of the palmoplantar surface of her hands and feet. The dorsum of her hands had numerous coalescing, shiny, flat-topped, hypopigmented papules (Fig. 2), and several of her fingernails had distal, V-shaped notching. Figure 1. Hypopigmented macules on the cheek and along the jawline Figure 2. Coalescing, hypopigmented papules on the dorsal aspect of the fingers and hand, with distal notching of the fingernails A punch biopsy from a papule on the dorsum of her hand was obtained. The epidermis had corps ronds present with focal areas of acantholysis above the basal layer (Fig. 3). The dermis had sparse, superficial, perivascular infiltrates composed of lymphocytes and histiocytes. These changes were consistent with our clinical diagnosis of Darier's disease (keratosis follicularis). Figure 3. Corps ronds (large arrow) and focal acantholysis with suprabasal clefts (small arrow) are present in the epidermis (hematoxylin and eosin; original magnification, ×,40) [source] Bilateral ankle arthritis with mediastinal lymphadenopathy: a clinician's perspectiveINTERNATIONAL JOURNAL OF RHEUMATIC DISEASES, Issue 3 2006Lalit DUGGAL Abstract Aim:, This study is a clinician's perspective of the association of bilateral ankle arthritis with mediastinal lymphadenopathy. Method:, Forty-three patients with bilateral ankle arthritis with mediastinal lymphadenopathy were included in a 14-month prospective follow-up study in our hospital. Complete history, examination and investigations were carried out. Result:, There were 27 female and 16 male patients. Ankle arthritis with tuberculous mediastinal lymphadenopathy was associated in 58.13%, sarcoidosis in 32.5% and 9.3% were non-specific. The patients were clustered in the spring-summer months. Erythema nodosum was found in 14.3%, polyarticular presentation in 25%. Thirteen out of 43 patients (28.2%) had biopsy/fine needle aspiration (FNA), of which 69.23% had histopathological evidence of tuberculosis. Conclusion:, The aetiology of bilateral ankle arthritis associated with mediastinal lymphadenopathy may be tuberculosis as opposed to sarcoidosis. There is a seasonal clustering of these cases. FNA of mediastinal lymphadenopathy is a fairly safe procedure and should be carried out when feasible, for confirmation of diagnosis. [source] Seasonal activity and abundance of Orosius orientalis (Hemiptera: Cicadellidae) at agricultural sites in Southeastern AustraliaJOURNAL OF APPLIED ENTOMOLOGY, Issue 2 2010P. Tr, bicki Abstract Orosius orientalis is a leafhopper vector of several viruses and phytoplasmas affecting a broad range of agricultural crops. Sweep net, yellow pan trap and yellow sticky trap collection techniques were evaluated. Seasonal distribution of O. orientalis was surveyed over two successive growing seasons around the borders of commercially grown tobacco crops. Orosius orientalis seasonal activity as assessed using pan and sticky traps was characterised by a trimodal peak and relative abundance as assessed using sweep nets differed between field sites with peak activity occurring in spring and summer months. Yellow pan traps consistently trapped a higher number of O. orientalis than yellow sticky traps. [source] Reproductive behaviour of a temperate serranid fish, Paralabrax clathratus(Girard), from Santa Catalina Island, California, U.S.A.JOURNAL OF FISH BIOLOGY, Issue 1 2006B. E. Erisman The reproductive behaviour of the kelp bass Paralabrax clathratus was studied on Santa Catalina Island, California, U.S.A. from April 2000 to September 2002. Adults formed aggregations of three to > 200 individuals, and spawning occurred within subgroups of three to 23 individuals that contained a single female. The gonado-somatic index (IG) of collected ripe males (mean = 5·8%, range = 0·5,13·1%) indicated a large investment in sperm production that is common in group-spawning fishes characterized by intense sperm competition. Spawning occurred 32 min before sunset to 120 min after sunset, and both males and females were capable of spawning multiple times during a single evening. Behavioural observations of adults and estimates of spawning periodicity from the collection of females with hydrated oocytes suggested that spawning occurred continuously throughout the summer months and showed no significant relationship with the lunar cycle. In general, the spawning behaviour of kelp bass was similar to other functionally gonochoric, group-spawning serranids. The dynamics of P. clathratus spawning aggregations, however, were inconsistent with that of tropical reef fish spawning aggregations, including the transient spawning aggregations of some tropical serranids. Aggregation spawning appeared to be an important component of the annual reproduction of this species. [source] Habitat selection by juvenile Atlantic salmon: the interaction between physical habitat and abundanceJOURNAL OF FISH BIOLOGY, Issue 4 2005R. D. Hedger The effect of physical river habitat variables on the distribution of juvenile Atlantic salmon Salmo salar L. in the Rivière de la Trinité, Québec, Canada, was examined using generalized additive modelling. A survey of Atlantic salmon fry and parr densities and habitat variables (flow velocity, water column depth and substratum size) was conducted in the summer months from 1984 to 1992. Clear patterns of habitat use existed: specific ranges of habitat variables were selected, with parr preferring greater velocities, depths and substratum sizes than fry. There was a large variation, however, in juvenile densities for given velocities, depths or substratum sizes, with this variation being greatest in optimal habitats. On examination of an individual year, interaction between the variables was found to explain some of the variation. On a year-to-year basis the juvenile Atlantic salmon population was found to exhibit an ,Ideal Free Distribution', which resulted in greatest variation in optimal habitats with year-to-year changes in population abundance. [source] | ||||||||||||||||||||||||||||||||||