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1.
The June 1991 eruption of Mt. Pinatubo in the Philippines produced one of the greatest volcanic aerosols in the last hundred years. The estimated net decrease of radiation may have peaked at 10% in the tropics. What was the impact of the Pinatubo aerosol on regional and global climate? Besides the expected net cooling of the average global surface temperature, correlation studies indicate that other types of climate anomalies may also be expected. These include the appearance of an El Niño event, decreased Indian monsoon rainfall, fewer tropical storms in the north Atlantic Ocean in 1991–1993, and normal to above normal winter rainfall in California in 1991/92, all of which were observed. A proposed physical mechanism for the almost-simultaneous occurrence of this constellation of climate anomalies is presented. The results of correlation studies between low-latitude volcanic aerosols and the El Niño/Southern Oscillation are presented in some detail as one example. The correlation between Indian monsoon rainfall and tropical storms in the north Atlantic Ocean is also shown and is updated for the most recent 5 years.  相似文献   

2.
Entomopathogenic fungi were isolated and identified from insects collected from the tropical forest and an agricultural area at El Eden Ecological Reserve, Quintana Roo, Mexico. These fungi were studied to determine their potential as biological control agents of greenhouse Trialeurodes vaporariorum (Homoptera: Aleyrodidae), and to contribute to the knowledge of biodiversity of this area. No pest insects were observed in the tropical forest. In contrast, all insects collected in the agricultural area were considered important pests by the local farmers, with the whitefly, as the most relevant, plentiful in Cucurbitaceae plants. From approximately 3400 collected insects in three different surveys, different anamorphic Ascomycetes were recovered. One isolate of Aspergillus sp., two of Penicillium sp., three of Paecilomyces marquandii, and three of Verticillium sp. out of 308 insects (2.9%) from three insect orders, Hymenoptera, Diptera and Isoptera in the tropical forest. In contrast, a higher number of fungal isolates were recovered from the agricultural area: three isolates from Aspergillus parasiticus, 100 of Fusarium moniliforme, one of Aschersonia sp., and 246 of Fusarium oxysporum out of 3100 insects (11.3%) from three insect orders, Homoptera, Coleoptera and Lepidoptera. The results of this study show Fusarium moniliforme and F oxysporum as highly virulent to infected insects in the agricultural area, with 100 and 246 isolates respectively, out of 350 infected insects of 3100 studied specimens. Laboratory whitefly nymph bioassays with isolates Ed29a of F. moniliforme, Ed322 of F. oxysporum, and Ed22 of P marquandii showed 96 to 97.5% insect mortality with no significant differences (P < 0.05) among them. F. oxysporum Ed322 produced no mortality when inoculated on tomato, bean, squash and maize seedlings (with and without injuries) compared to the 100% mortality caused by phytopathogenic strains, F. oxysporum f. sp. lycopersici and F. oxysporum f. sp. radicis lycopersici.  相似文献   

3.

Objectives

To provide an accurate estimate of antenatal HIV screening and its determinants among pregnant women in El Salvador and help local authorities make informed decisions for targeted interventions around mother-to-child transmission (MTCT).

Methods

A total sample of 4,730 women aged 15-49 years were interviewed from a random sample of 3,625 households. We collected data on antenatal care services, including HIV screening, during last pregnancy through a pre-established questionnaire. We used a backward elimination multivariate logistic regression model to examine the association between HIV screening and sociodemographic and health care-related factors.

Results

A total of 2,929 women were included in this analysis. About 98% of participants reported receiving antenatal care, but only 83% of these reported being screened for HIV. Screening was lower in geographic areas with higher HIV incidence and ranged from 69.1% among women who were not seen by a physician during antenatal care, to 93.7% among those who attended or completed college. Odds for screening varied also by age, employment status, household economic expenditure, possession of health care coverage, health care settings, and number of antenatal care visits.

Conclusions

We found disparities in HIV screening during antenatal care at the environmental, social, demographic, and structural levels despite a high uptake of antenatal care in El Salvador. Our findings should urge health authorities to tailor and enhance current strategies implemented to eliminate MTCT and reduce inequities and HIV morbidity among women in El Salvador.  相似文献   

4.
5.
Waterbird abundance, and seasonal and spatial distribution, were studied in two natural water pools at Jalisco, Mexico, from December 1997 through November 1998. Maximum monthly abundance in Agua Dulce lake and El Ermita?o estuary was 86 471 birds (29 686 in Agua Dulce and 56 785 in Ermita?o), with a total cummulative abundance of 179 808 individuals (66 976 in Agua Dulce and 112 832 in Ermita?o). A total of 87 waterbirds species were recorded, 78 in Agua Dulce and 73 in Ermita?o. The higher species richness and abundance was observed during winter, when migratory species arrived. Most species prefered shallow waters, except seabirds which prefered protected areas such as dunes in Agua Dulce. Other groups, like clucks and related species. prefered low salinity areas, for example in the south-east area of Ermita?o. The higher abundance of the shorehirds was found when the water level on the estuary was low. Herons were seen often at areas with high salinity and influenced by tides (e.g. mouth of Ermita?o).  相似文献   

6.
In Peru, it was hypothesized that epidemic cholera in 1991 was linked to El Niño, the warm phase of El Niño–Southern Oscillation. While previous studies demonstrated an association in 1997–1998, using cross-sectional data, they did not assess the consistency of this relationship across the decade. Thus, how strong or variable an El Niño–cholera relationship was in Peru or whether El Niño triggered epidemic cholera early in the decade remains unknown. In this study, wavelet and mediation analyses were used to characterize temporal patterns among El Niño, local climate variables (rainfall, river discharge, and air temperature), and cholera incidence in Piura, Peru from 1991 to 2001 and to estimate the mediating effects of local climate on El Niño–cholera relationships. The study hypothesis is that El Niño-related connections with cholera in Piura were transient and interconnected via local climate pathways. Overall, our findings provide evidence that a strong El Niño–cholera link, mediated by local hydrology, existed in the latter part of the 1990s but found no evidence of an El Niño association in the earlier part of the decade, suggesting that El Niño may not have precipitated cholera emergence in Piura. Further examinations of cholera epicenters in Peru are recommended to support these results in Piura. For public health planning, the results may improve existing efforts that utilize El Niño monitoring for preparedness during future climate-related extremes in the region.  相似文献   

7.

Reef Sites

Coral survivors of the 1982–83 El Niño-Southern Oscillation, Galápagos Islands, Ecuador  相似文献   

8.
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10.
The distribution, abundance and standing crop biomass of chironomid larvae were determined at one-meter depth intervals along three radial transects. Samples were collected by coring soft sediments while diving. Three genera were found in the lake: Chironomus sp. (collector-filtering larvae), Ablabesmyia sp. (predatory larvae) and Goeldichironomus sp. (collector-filtering larvae). Standing crop densities of chironomids, averaged over the entire lake, varied from 30,594 larvae/m2 to 11,428 larvae/m2 at different depths. No statistically significant zonation in density was found for the two most common taxa, Chironomus sp. (87.8% of specimens) and Ablabesmyia sp. (9.0%), however the deepest zones (>4 m) had the lowest estimated densities. Significant differences in standing crop biomass were detected, with the 6 m depth having greatest biomass. The increase in standing crop biomass was a function of (1) lower frequency of first instars of Chironomus sp. and Ablabesmyia sp. at 6 m (2) higher average larval biomass of both species at 6 m and (3) very significant increase in average biomass of fourth instars of Chironomus sp. at 6 m compared to fourth instars at shallower depths. These results indicate that the lentic chironomids of this isolated oceanic habitat consist of a small number of species that are ecological generalists and tolerant of low oxygen concentrations.  相似文献   

11.
Abstract: In order to understand the vertical distribution of planktonic organisms in the oceans, it is important to consider a number of factors. Including oceanic circulation patterns, the vertical structure of the water column and the vertical position of the thermocline. This study examines the hydrography of Golfo Dulce, a tropical fjord -like embayment in the Eastern Tropical Pacific, and the influence of the 1997-1998 ENSO on the system. Five sampling stations were selected and visited once a month for two years in order to obtain vertical profiles of temperature (degrees C), salinity (% per hundred) and dissolved oxygen (mg O2/l). Results show a strong vertical stratification of the water column associated to the morphology of Golfo Dulce's basin and to the effects of ENSO. Moreover, the existence of significant differences between the hydrographic characteristics of the inner and outer parts of the basin was detected. Finally, biannual events in the influx of cold, high salinity, and oxygen rich oceanic water masses into the basin were detected. These events might be related to the same forces driving the coastal upwelling system in the Gulf of Panama.  相似文献   

12.
Hand, foot and mouth disease (HFMD) was an emerging viral infectious disease in recent years in Shenzhen. The underlying risk factors have not yet been systematically examined. This study analyzed the short-term effect of El Niño-Southern Oscillation on pediatric HFMD in Shenzhen, China. Daily count of HFMD among children aged below 15 years old, Southern Oscillation Index (SOI), and weather variables were collected to construct the time series. A distributed lag non-linear model was applied to investigate the effect of daily SOI on pediatric HFMD occurrence during 2008–2010. We observed an acute effect of SOI variation on HFMD occurrence. The extremely high SOI (SOI = 45, with 0 as reference) was associated with increased HFMD, with the relative risk (RR) being 1.66 (95% Confidence Interval [CI]: 1.34–2.04). Further analyses of the association between HFMD and daily mean temperature and relative humidity supported the correlation between pediatric HFMD and SOI. Meteorological factors might be important predictors of pediatric HFMD occurrence in Shenzhen.  相似文献   

13.
The ichthyofauna fished in Bahía de Navidad, Jalisco, Mexico in the Central Pacific was surveyed during 1998. Six thousand nine hundred and fourty-four organisms of 130 species were caught which weighted 3,231 kg. Nearly 30% of the species belonged to Carangidae. Haemulidae and Sciaenidae. The most important species in number and biomass were Microlepidotus brevipinnins, Caranx caninus and C. caballus. Species number, abundance and biomass fluctuated during the year. The largest number of species was caught in June (61), the minimum in March (33). January had the maximum abundance (1,397 organisms), while the minimum was obtained during August (251). The maximum biomass values were from January (556.5 kg), and the lowest from August (114.7 kg). Eighteen species accumulated 87% of the total abundance, while 20 species represented 86.3% of the biomass. There were large in differences species number, abundance and biomass nets of different mesh size.  相似文献   

14.
This study provides a case history of the impact of the 1998 El Ni no event on a lake charr population in a shallow (maximum depth = 13m) lake in the southern boreal shield ecozone of Ontario. The lake lost its native charr population by acidification from air-borne pollutants in the 1950–1960s. A naturally reproducing population was re-established through hatchery stocking after the water quality improved in the 1980s. The warm years triggered by the El Ni no event exposed fish to bottom water temperatures of 20°C for several weeks and resulted in the loss of all hatchery-reared juveniles that were released in 1998. A few adults survived the warm years by making use of cold water refuge areas (groundwater seepage). This study shows how climate change can eliminate charr populations at the margins of their range. It also illustrates the potential confounding effects of climate warming on aquatic ecosystems already subject to other stressors.  相似文献   

15.
16.
Skull morphology results from the bone remodelling mechanism that underlies the specific bone growth dynamics. Histological study of the bone surface from Neanderthal mandible specimens of El Sidrón (Spain) provides information about the distribution of the remodelling fields (bone remodelling patterns or BRP) indicative of the bone growth directions. In comparison with other primate species, BRP shows that Neanderthal mandibles from the El Sidrón (Spain) sample present a specific BRP. The interpretation of this map allows inferences concerning the growth directions that explain specific morphological traits of the Neanderthal mandible, such as its quadrangular shape and the posterior location of the mental foramen.  相似文献   

17.
Droughts associated with the El Niño-Southern Oscillation (ENSO) affected fishes of brackish-water lagoons, freshwater swamps and a rainforest creek in Suriname, South America. The mean rainfall in the period August to February in 22 El Niño years was 76.6% of the mean rainfall in the same months of non-El Niño years. In the period 1900–1999, three out of four years in which an extreme drought (rainfall less then 60% of the mean value) occurred were El Niño years. The recent 1997/1998 ENSO event caused the second most severe drought in a 100-year record. Drying up of brackish-water lagoons, freshwater swamps and rainforest creeks was observed during El Niño-related droughts. In the lagoons ariid catfish died first, followed by snook, tilapia, mullet and tarpon, respectively. Landings of lagoon fish were positively correlated with rainfall in the period August–February. During the El Niño-related drought we observed failure of reproduction in three species of callichthyid armoured catfish in both coastal freshwater swamps and a rainforest creek in the interior. In the El Niño year 1997/1998, the no flow period of the rainforest creek was extended by four months beyond the long dry season and the dissolved oxygen levels in the dry-season pools dropped to 1.27mg O2l–1 (as compared to 4.53mg O2l–1 under running water conditions). Other fish species of the rainforest creek also showed decreased reproductive success in the El Niño year. We suggest that the stochastic effects of El Niño-related drought may be an important non-equilibrium component in the ecology of neotropical inland fish communities.  相似文献   

18.
摘要:【目的】利用高通量蛋白质组分析技术,初步探讨El Tor型霍乱弧菌的分泌性蛋白组成,为进一步的功能研究打下基础。【方法】选取El Tor型霍乱弧菌流行株N16961和非流行株92-3,用双相电泳和激光辅助解析-飞行时间串联质谱(Matrix Assisted Laser Desorption Ionization-Time of Flight,MALDI-TOF)技术对培养上清的全部蛋白质组份进行鉴定和分析。【结果】从N16961株培养上清中可检测到206个蛋白点,并鉴定出49种蛋白;从92-3株培养上清中可检测到236个蛋白点,并鉴定出42种蛋白,两株菌共鉴定蛋白68种,其中经预测含有信号肽的蛋白占总数的55.88%(38/68)。按功能不同将所鉴定出的蛋白分为10类,其中代谢酶、蛋白折叠/伴侣蛋白、蛋白合成以及信号传导相关蛋白占全部培养上清蛋白数的36.76%,转运蛋白占14.71%,鞭毛蛋白占11.76%,降解酶占10.29%,外膜蛋白占5.88%,毒素占1.47%,在所鉴定出的蛋白中有11种具有信号肽的假想蛋白和2种功能未知的蛋白为首次被实验证实可出现在霍乱弧菌培养上清中,占19.12%。【结论】初步获得了El Tor型霍乱弧菌流行株和非流行株的分泌性蛋白谱及其组成特征,并提示与霍乱弧菌致病关系密切的鞭毛蛋白在胞外释放机制、红血球凝集素/蛋白酶在非流行株中的高表达特征等值得高度关注。  相似文献   

19.
The genus Ochrolechia is widespread in Spain and Portugal and now includes 14 species, 1 form and 4 chemical races (11 species and 3 chemical races are epiphytes, 2 species, 1 form and 1 chemical race are saxicolous and one species is muscicolous). We propose a new combination: O. dalmatica (Erichsen) Boqueras. Eight species are excluded from the Spanish and Portuguese floras: O. aggregata (Bagl.) Verseghy, O. anomala Verseghy, O. glaucescens (Hue) Zahlbr., O.frigida (Sw.) Lynge, O. pseudotartarea (Vain.) Verseghy, O. rosella Müll. Arg., O. subpallescens Verseghy, O. tenuissima Verseghy, O. crozalsiana Clauzade et Vêzda is included in O. tartarea. The criteria for the identification of these species are: 1 ) the chemical substances (the presence/absence of gyrophoric acid in the thallus and/or in the apothecia determines the groups inside of the genus, the presence of alectoronic acid determines the chemical races); 2) thallus with or without soredia or isidia; 3) the presence of pruina on the disc; and 4) the substratum. A key for the identification to all mentioned species is included.  相似文献   

20.

Background

The mosquito-borne dengue viruses are a major public health problem throughout the tropical and subtropical regions of the world. Changes in temperature and precipitation have well-defined roles in the transmission cycle and may thus play a role in changing incidence levels. The El Niño Southern Oscillation (ENSO) is a multiyear climate driver of local temperature and precipitation worldwide. Previous studies have reported varying degrees of association between ENSO and dengue incidence.

Methods and Findings

We analyzed the relationship between ENSO, local weather, and dengue incidence in Puerto Rico, Mexico, and Thailand using wavelet analysis to identify time- and frequency-specific association. In Puerto Rico, ENSO was transiently associated with temperature and dengue incidence on multiyear scales. However, only local precipitation and not temperature was associated with dengue on multiyear scales. In Thailand, ENSO was associated with both temperature and precipitation. Although precipitation was associated with dengue incidence, the association was nonstationary and likely spurious. In Mexico, no association between any of the variables was observed on the multiyear scale.

Conclusions

The evidence for a relationship between ENSO, climate, and dengue incidence presented here is weak. While multiyear climate variability may play a role in endemic interannual dengue dynamics, we did not find evidence of a strong, consistent relationship in any of the study areas. The role of ENSO may be obscured by local climate heterogeneity, insufficient data, randomly coincident outbreaks, and other, potentially stronger, intrinsic factors regulating transmission dynamics. Please see later in the article for the Editors'' Summary  相似文献   

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