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181.
The colonization of foliage-dwelling spiders into insecticide-free “micro” apple orchards at two distances (10 and 50 m) from an adjacent source habitat of deciduous forest was quantified in southern Québec, Canada. Both colonization rate and composition of colonizing spider assemblages were affected by distance at this small spatial scale: the samples from the micro-orchards 10 m from the forest were intermediate in composition between the assemblages in the deciduous forest and those in the micro-orchards 50 m from the forest. Spider species found in micro-orchards were the same as those documented from collections from older, insecticide-free orchards although species evenness was higher in the older orchards indicating that species composition shifts over time within the habitat. Maintaining deciduous forest near to orchards will provide a source of annual colonists for spider populations within the orchard. 相似文献
182.
Buffalo River is an important water resource in the Eastern Cape Province of South Africa. Over a 1-year period (August 2010?CJuly 2011), we assessed the prevalence of human adenoviruses (HAdVs) at a total of 6 sites on the river and three dams along its course. HAdVs were detected by real-time quantitative PCR in about 35?% of the samples with concentrations ranging from 1.2?×?101 genome copies (GC)/l to 4.71?×?103 GC/l. HAdVs were detected at 5 of the 6 sampling sites with the detection rate ranging from 8.3?% at Rooikrantz Dam to 92?% at Parkside. The HAdV concentrations across the sampling sites were as follows: Parkside (3.25?×?102?C4.71?×?103?GC/); King William??s Town (1.02?×?102?C4.56?×?103?GC/l); and Eluxolzweni (1.17?×?102?C3.97?×?102 GC/l). Significantly (P?<?0.05) higher concentrations were detected at the non-dam sites compared to the dam sites. A very low mean concentration of 1.86?×?101 HAdV GC/l was observed at Bridle Drift Dam. While HAdVs were detected only once at Rooikrantz Dam (1.74?×?101?GC/l), no HAdV was detected at Maden Dam. Epidemiologically important serotypes, Ad40/41, constituted 83.3?%, while Ad21 made up 16.7?% of the all HAdVs detected and were characterized by qualitative PCR. The Buffalo River presents a public health risk heightened by the presence of Ad 40/41 and Ad21. Our results make imperative the need for assessing water sources for viral contamination in the interest of public health. This work is a significant contribution to the molecular epidemiology of adenoviruses and to the best of our knowledge this is the first report on detection of enteric virus from surface waters in the Eastern Cape. 相似文献
183.
In this paper, an experimental device using non-contact displacement sensors for the investigation of milling tool behaviour is presented. It enables the recording of high frequency tool vibrations during milling operations. The aim of this study is related to the surface topography prediction using tool displacements and based on tool center point methodology. From the recorded signals and the machining parameters, the tool deformation is modeled. Then, from the calculated deflection, the surface topography in 3D can be predicted. In recent studies, displacements in XY plane have been measured to predict the surface topography in flank milling. In this article, the angular deflection of the tool is also considered. This leads to the prediction of surfaces obtained in flank milling as well as in end milling operations. Validation tests were carried out: the predicted profiles were compared to the measured profile. The results show that the prediction corresponds well in shape and amplitude with the measurement. 相似文献
184.
van Ginneken V Ballieux B Antonissen E van der Linden R Gluvers A van den Thillart G 《Die Naturwissenschaften》2007,94(2):128-133
In birds and mammals, the thyroid gland secretes the iodothyronine hormones of which tetraiodothyronine (T4) is less active
than triiodothyronine (T3). The action of T3 and T4 is calorigenic and is involved in the control of metabolic rate. Across
all vertebrates, thyroid hormones also play a major role in differentiation, development and growth. Although the fish thyroidal
system has been researched extensively, its role in thermogenesis is unclear. In this study, we measured overall heat production
to an accuracy of 0.1 mW by direct calorimetry in a free-moving European eel (Anguilla anguilla L.) with different thyroid status. Hyperthyroidism was induced by injection of T3 and T4, and hypothyroidism was induced
with phenylthiourea. The results show for the first time at the organismal level, using direct calorimetry, that neither overall
heat production nor overall oxygen consumption in eels is affected by hyperthyroidism. Therefore, we conclude that the thermogenic
metabolism-stimulating effect of thyroid hormones (TH) is not present with a cold-blooded fish species like the European eel.
This supports the concept that TH does not stimulate thermogenesis in poikilothermic species. 相似文献
185.
186.
Grais RF Coulombier D Ampuero J Lucas ME Barretto AT Jacquier G Diaz F Balandine S Mahoudeau C Brown V 《Disasters》2006,30(3):364-376
Emergencies resulting in large-scale displacement often lead to populations resettling in areas where basic health services and sanitation are unavailable. To plan relief-related activities quickly, rapid population size estimates are needed. The currently recommended Quadrat method estimates total population by extrapolating the average population size living in square blocks of known area to the total site surface. An alternative approach, the T-Square, provides a population estimate based on analysis of the spatial distribution of housing units taken throughout a site. We field tested both methods and validated the results against a census in Esturro Bairro, Beira, Mozambique. Compared to the census (population: 9,479), the T-Square yielded a better population estimate (9,523) than the Quadrat method (7,681; 95% confidence interval: 6,160-9,201), but was more difficult for field survey teams to implement. Although applicable only to similar sites, several general conclusions can be drawn for emergency planning. 相似文献
187.
Loïc A. Hardouin Dominique Robert Vincent Bretagnolle 《Behavioral ecology and sociobiology》2008,62(12):1909-1918
The dawn chorus is a striking feature of spring mornings and a characteristic behaviour of many bird species, particularly
the passerines. Dawn singing has been considered a reliable signal of male quality for mate and rival assessment. Singing
is presumed to be relatively costly at dawn both because air temperatures are relatively low and because birds have not fed
overnight. Models of optimal daily routine predict the existence of a “dusk chorus” in nocturnal birds, although this prediction
has received little empirical attention. Nocturnal birds at dusk may be energy-limited because of a lack of daytime feeding,
and singing at dusk may thus ensure signal reliability. Here, we used an observational and experimental approach to study
vocal behaviour at dusk and dawn in a nocturnal raptor, the little owl Athene noctua. We assess whether male little owls adjust their vocal behaviour according to feeding stage (i.e. period of the night), ambient
air temperature and territorial context (i.e. spontaneous calling behaviour vs elicited calling by intrusion). Across different
temperatures, we find that both spontaneous vocal activity and inter-individual variability in call duration increased at
dusk, clearly indicating a dusk chorus phenomenon. Results from playback presentations suggest that food, rather than air
temperature, is likely to be more constraining at dusk. We discuss how comparing dusk and dawn choruses in nocturnal and diurnal
species can provide insights into both mechanistic and functional aspects of signalling behaviour. 相似文献
188.
Dubreuil V Debortoli N Funatsu B Nédélec V Durieux L 《Environmental monitoring and assessment》2012,184(2):877-891
The transformation of forest into pastures in the Brazilian Amazon leads to significant consequences to climate at local scale.
In the region of Alta Floresta (Mato Grosso, Brazil), deforestation has been intense with over half the forests being cut
since 1970. This article first examines the evolution of precipitation observed in this region and shows a significant trend
in the decrease in total precipitation especially at the end of the dry season and at the beginning of the rainy season. The
study then compares the temperatures measured in cleared and forested sectors within a reserve in the area of Alta Floresta
(Mato Grosso, Brazil) between 2006 and 2007. The cleared sector was always hotter and drier (from 5% to 10%) than the forested
area. This difference was not only especially marked during the day when it reached on average 2°C but also seemed to increase
during the night with the onset of the dry season (+0.5°C). The Urban Heat Island effect is also evident especially during
the night and in the dry season. 相似文献
189.
Isabelle J. Brisson Patrick Levallois Hélène Tremblay Jean Sérodes Christian Deblois Jeffrey Charrois Vincent Taguchi Jessica Boyd XingFang Li Manuel J. Rodriguez 《Environmental monitoring and assessment》2013,185(9):7693-7708
The spatiotemporal presence of eight N-nitrosamines in the water of seven supply systems in Quebec considered to be susceptible to these emerging disinfection by-products was evaluated. This is the first study on the presence of N-nitrosamines in drinking water utilities in Quebec. Seven sampling campaigns were carried out at several sampling points in each of the systems over a period of 1 year. The results show that N-nitrosamines, primarily N-nitrosodimethylamine (NDMA), were not commonly detected in the water of the facilities under study (10 % of samples). The concentrations measured were lower than those reported in recent North American studies. None of the 195 samples taken exceeded the Ontario standard of 9 ng/L for NDMA (maximum value observed of 3.3 ng/L). N-nitrosomethylethylamine and N-nitrosopiperidine were detected once, with concentrations of 3.7 and 6.0 ng/L, respectively. Chloramination was identified as being the main risk factor regarding the presence of N-nitrosamines, but water quality and some operating parameters, in particular disinfectant residual, also seem to be related to their presence. NDMA concentrations at the end of the distribution systems were generally higher than water leaving the plant. No seasonal trends were observed for the formation of N-nitrosamines in the investigated supply systems. Finally, an association between the presence of N-nitrosamines and the levels of trihalomethanes and haloacetic acids was observed in some facilities. 相似文献
190.
Timothy Sibanda Vincent N. Chigor Anthony I. Okoh 《Environmental monitoring and assessment》2013,185(8):6579-6590
We assessed the incidence of faecal-indicator bacteria in Tyume River over a 12-month period between August 2010 and July 2011. Total coliforms, faecal coliforms and enterococci were determined by the membrane filtration method. Total coliforms were detected in counts ranging from 2.1?×?102 to 3.4?×?104?CFU/100 ml. Faecal coliform counts ranged from 1?×?102 to 1.6?×?104?CFU/100 ml while enterococci counts were in the range of 3.3?×?101 to 5.1?×?103?CFU/100 ml. Indicator bacteria counts increased from upstream to downstream sampling sites. Counts of indicator bacteria at all sites were significantly affected by seasonal changes. The bacteriological qualities of the river water were poor, exceeding the guideline of 200 CFU/100 ml and 33 CFU/100 ml for faecal coliforms and enterococci, respectively, for recreational water. Faecal coliform counts also exceeded the 1,000 CFU/100 ml guideline for water used in fresh produce irrigation. Microbial source tracking results showed that faecal pollution was predominantly of human origin during spring at all sampling sites. During other seasons, human faecal pollution was largely confined to midstream and downstream sampling sites. Generally, the presence of faecal-indicator bacteria in the river water samples suggests faecal pollution of this freshwater resource, raising the possibility of the presence of pathogenic microorganisms in the water and a threat to public health. 相似文献