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Annie‐Claude Parent François Anctil Véronique Cantin Marie‐Amélie Boucher 《Journal of the American Water Resources Association》2008,44(3):679-688
Abstract: Snowmelt largely affects runoff in watersheds in Nordic countries. Neural networks (NN) are particularly attractive for streamflow forecasting whereas they rely at least on daily streamflow and precipitation observations. The selection of pertinent model inputs is a major concern in NNs implementation. This study investigates performance of auxiliary NN inputs that allow short‐term streamflow forecasting without resorting to a deterministic snowmelt routine. A case study is presented for the Rivière des Anglais watershed (700 km2) located in Southern Québec, Canada. Streamflow (Q), precipitations (rain R and snow S, or total P), temperature (T) and snow lying (A) observations, combined with climatic and snowmelt proxy data, including snowmelt flow (QSM) obtained from a deterministic model, were tested. NN implemented with antecedent Q and R produced the largest gains in performance. Introducing increments of A and T to the NNs further improved the performance. Long‐term averages, seasonal data, and QSM failed to improve the networks. 相似文献
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The present study examined the mode and timing of reproduction of poorly understood deep-water octocorals and the environmental
factors that may influence their reproductive patterns. Data on reproductive characteristics of the octocoral Drifa glomerata (Alcyonacea: Nephtheidae) collected between 2004 and 2007 at ca. 100–330 m depth off Newfoundland and Labrador (eastern Canada)
were compared among years, months and depth ranges. No male gonad was ever observed during the study. The ratio of fertile
colonies possessing large pinkish polyps with oocytes/planulae was >50% throughout the year. The number of brooded planula
larvae within a single fertile polyp varied between 1 and 10 for a total of approximately 40–3,000 in a whole colony. The
size of oocytes and/or planulae was consistently greater in the polyps than in the branchlets, indicating that the development
pathway of oocytes to planulae is from the branchlets to the polyps. Although larval production seemed to persist year round,
the onset of major planulation events occurred in December–January of two consecutive years, when large mature planulae were
released in correlation with the first increase of photoperiod and maximum temperature at 150 m. A second peak in planulation
between April and early June followed the phytoplankton bloom. Seasonal trends were more apparent in colonies from <200 m,
and the planula index varied among sampling depths and years. Larval release in a live colony under laboratory conditions
occurred between January and June 2008, closely following predictions based on field samples. 相似文献
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Christel Thauvin-Robinet Thierry Rousseau Nicole Laurent Christine Durand Catherine Maingueneau Valérie Cormier-Daire Paul Sagot Laurence Faivre Annie Nivelon-Chevallier 《黑龙江环境通报》2002,22(8):710-714
We report here the fourth case of hypomandibular faciocranial dysostosis (HFD). The diagnosis was made at birth on the association of severe retrognathia, microstomia, severe hypoglossia with glossoptosis, persistent buccopharyngeal membrane, median cleft palate, bifid uvula, down-slanting palpebral fissures, short nose with anteverted nares, laryngeal hypoplasia, and low-set ears. A severe microstomia and micrognathia were detected by ultrasound at 31 weeks of gestation. Interestingly, even though the present case exhibits many facial dysmorphic features characteristic of HFD, craniosynostosis was absent. This report suggests that craniosynostosis is not mandatory for the diagnosis of this condition. Furthermore, we present a new argument for an autosomal recessive mode of inheritance for HFD. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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Ona LF Alberto AM Prudente JA Sigua GC 《Environmental science and pollution research international》2006,13(3):177-183
Background Aims, and Scope. Lead (Pb) is a naturally occurring element that poses environmental hazards when present at elevated concentration.
It is being released into the environment because of industrial uses and from the combustion of fossil fuels. Hence, Pb is
ubiquitous throughout global ecosystems. The existence of potentially harmful concentrations of Pb in the environment must
be given full attention. Emissions from vehicles are major source of environmental contamination by Pb. Thus, it becomes imperative
that concentrations of Pb and other hazardous materials in the environment not only in the Philippines, but elsewhere in the
world be adequately examined in order that development of regulations and standards to minimize risk associated with these
materials in urban areas is continued. The objectives of this study were: (1) to determine the levels of Pb in soil from selected
urbanized cities in central region of the Philippines; (2) to identify areas with soil Pb concentration values that exceed
estimated natural concentrations and allowable limits; and (3) to determine the possible sources that contribute to elevated
soil Pb concentration (if any) in the study area.
Methods This study was limited to the determination of Pb levels in soils of selected urbanized cities located in central region
in the Philippines, namely: Site 1 – Tarlac City in Tarlac; Site 2 – Cabanatuan City in Nueva Ecija; Site 3 – Malolos City
in Bulacan; Site 4 – San Fernando City in Pampanga; Site 5 – Balanga City in Bataan; and Site 6 – Olongapo City in Zambales.
Soil samples were collected from areas along major thoroughfares regularly traversed by tricycles, passenger jeepneys, cars,
vans, trucks, buses, and other motor vehicles. Soil samples were collected from five sampling sites in each of the study areas.
Samples from the selected sampling sites were obtained approximately 2 to 3 meters from the road. Analysis of the soil samples
for Pb content was conducted using an atomic absorption spectrophotometer. This study was conducted from 2003 to 2004. Since
this study assumed that vehicular emission is the major source of Pb contamination in urban soil, other information which
the researchers deemed to have bearing on the study were obtained such as relative quantity of each gasoline type disposed
of in each city within a given period and volume of traffic in each sampling site. A survey questionnaire for gasoline station
managers was prepared to determine the relative quantity of each fuel type (diesel, regular gasoline, premium gasoline, and
unleaded gasoline) disposed of or sold within a given period in each study area.
Results and Discussion Analysis of soil samples for Pb content showed the presence of Pb in all the soil samples collected from the 30 sampling
sites in the six cities at varying concentrations ranging from 1.5 to 251 mg kg–1. Elevated levels of Pb in soil (i.e. greater
than 25 mg kg–1 Pb) were detected in five out of the six cities investigated. Site 4 recorded the highest Pb concentration
(73.9 ± 94.4 mg kg–1), followed by Site 6 (56.3 ± 17.1 mg kg–1), Site 3 (52.0 ± 33.1 mg kg–1), Site 5 (39.3 ± 19.0 mg kg–1),
and Site 2 (38.4 ± 33.2 mg kg–1). Soil Pb concentration in Site 1 (16.8 ± 12.2 mg kg–1) was found to be within the estimated
natural concentration range of 5 to 25 mg kg–1. Site 1 registered the least Pb concentration. Nonetheless, the average Pb
concentration in the soil samples from the six cities studied were all found to be below the maximum tolerable limit according
to World Health Organization (WHO) standards. The high Pb concentration in Site 4 may be attributed mainly to vehicular emission.
Although Site 4 only ranked 3rd in total volume of vehicles, it has the greatest number of Type B and Type C vehicles combined.
Included in these categories are diesel trucks, buses, and jeepneys which are considered the largest contributors of TSP (total
suspended particles) and PM10 (particulate matter less than 10 microns) emissions.
Conclusion Only one (San Juan in Site 4) of the thirty sampling sites recorded a Pb concentration beyond the WHO permissible limit of
100 mg kg–1. San Juan in Site 4 had a Pb concentration of >250 mg kg–1. On the average, elevated Pb concentration was evident
in the soil samples from San Fernando, Olongapo, Malolos, Balanga, and Cabanatuan. The average soil Pb concentrations in these
cities exceeded the maximum estimated natural soil Pb concentration of 25 mg kg–1. Average soil Pb concentration in Site 1
(16.8 mg kg–1) was well within the estimated natural concentration range of 5 to 25 mg kg–1. Data gathered from the study
areas showed that elevated levels of Pb in soil were due primarily to vehicular emissions and partly to igneous activity.
Recommendation and Outlook The findings of this study presented a preliminary survey on the extent of Pb contamination of soils in urban cities in central
region of Philippines Island. With this kind of information on hand, government should develop a comprehensive environmental
management strategy to address vehicular air pollution in urban areas, which shows as one of the most pressing environmental
problems in the country. Basic to this is the continuous monitoring of Pb levels and other pollutants in air, soil, and water.
Further studies should be conducted to monitor soil Pb levels in the six cities studied particularly in areas with elevated
Pb concentration. The potential for harm from Pb exposure cannot be understated. Of particular concern are children who are
more predisposed to Pb toxicity than adults. Phytoremediation of Pb-contaminated sites is strongly recommended to reduce Pb
concentration in soil. Several studies have confirmed that plants are capable of absorbing extra Pb from soil and that some
plants, grass species in particular, and can naturally absorb far more Pb than others. 相似文献