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At least 163 records · Page 9Linked to original sources
PubMed1991

Parasitism of newly-hatched Aedes sierrensis (Diptera: Culicidae) larvae by Lambornella clarki (Ciliophora: Tetrahymenidae) following habitat flooding.

Host-parasite interactions between Lambornella clarki (Ciliophora: Tetrahymenidae) and its natural host, Aedes sierrensis (Diptera: Culicidae), were studied in newly flooded treeholes in northern California between 1986 and 1989. First instar host larvae hatched within 1 to 4 hr of flooding, while free-living trophonts of L. clarki appeared between 7 and 24 hr. As early as 24 hr after flooding, ciliates initiated the first parasite cycle by forming cuticular cysts on first instar larvae; by 64 hr, cysts were observed on larvae collected from all positive holes during all years. While larvae with as many as 12 cysts were observed, most supported only 1 cyst, and successful infections were established by the entry of a single ciliate into the host's hemocoel. Among treehole populations, the proportion of larvae with L. clarki cysts ranged from 2 to 100% at 48 hr indicating that enzootics and epizootics develop rapidly in newly flooded treeholes. Average attack rates from all holes by year ranged between 17.0 and 44.4%. Ciliates began entering hosts 48 to 72 hr after flooding, but some larvae escaped parasitization by molting to the second instar before ciliates penetrated the cuticle. In some treeholes, opportunistic microorganisms entered larvae with the invading ciliates and killed both the host and parasite.

Aedes↗
PubMed2005

Treading water. The long-term impact of the 1998 flood on nutrition in Bangladesh.

Bangladesh was hit by the worst flood in over a century in the summer of 1998. Although many households were able to smooth consumption expenditure, not everyone was able to maintain adequate calorie consumption. As a consequence, the nutritional status of children in households that were more severely exposed to the flood deteriorated. We use a three round panel data set to investigate which households were better protected from longer term nutritional crises, and whether the health of flood-exposed children recovered to the level of those who were not exposed. The evidence suggests that children exposed to the flood were adversely affected by the shock to their health and did not recover within the survey period. The results also suggest that ex ante government programs were more effective than ex post interventions to protect the heath of children from the impact of the flood.

Age Distribution↗
PubMed2004

Sensing and signalling during plant flooding.

Flooding is a major issue for plant survival in many regions of the world. Soil inundation induces multiple plant physiological dysfunctions, leading to a decline in plant growth and survival capacity. Some of the most important effects of flooding include a reduction in water and nutrient uptake and a decrease in metabolism. Prolonged soil flooding will also ultimately lead to anoxia conditions with profound effects on plant respiratory metabolism. However, it is still unclear which signals and which sensory mechanisms are responsible for triggering the plant response. In contrast, it is now established that flooding responses are typified by enhanced ethylene production, accompanied by a signalling cascade which includes a network of hormones and other common secondary signalling molecules. In recent years, there has been significant progress in the understanding of some of the signalling pathways involved during plant stress responses. Here, we present an overview of recent hypothesises on sensing and signalling during plant flooding.

Adaptation, Physiological↗
PubMed2005

Elevated methylmercury concentrations and loadings during flooding in Minnesota rivers.

Previous studies have identified flooded landscapes (e.g., wetlands, impoundments) as sites of elevated methylmercury (MeHg) production. Here we report MeHg and total Hg (THg) concentrations and mass loadings in rivers in Minnesota during major flooding episodes in the summer of 2002. Frequent intense precipitation events throughout the summer resulted in extraordinarily wet conditions in east-central and northwestern Minnesota. Streamflow remained at record-setting high levels in many rivers and streams in these regions for several weeks. We observed high concentrations of MeHg (>1.4 ng/L) accompanied by high MeHg/THg ratios (0.39 to 0.50) in the Roseau River in northwestern Minnesota and in the Elk and Rum Rivers in east-central Minnesota. Very high MeHg mass loadings were observed in the Mississippi River just upstream of Minneapolis on July 17 (51 g MeHg/day) and July 23 (42 g MeHg/day), when MeHg concentrations at this site were 0.89 and 0.99 ng/L, respectively. The elevated MeHg concentrations in the Roseau River were associated with low dissolved oxygen and high dissolved reactive phosphorus concentrations, both of which are characteristic of anoxic waters. These rivers drain landscapes containing varying amounts of wetlands, and some of the MeHg discharged is thought to have been flushed from anoxic wetland soils. In addition, the flooding of vast areas of normally dry land surfaces probably also resulted in increased MeHg production, adding to the quantities of MeHg exported from these watersheds. Changing climate patterns are expected to result in more frequent heavy precipitation and flooding events in Minnesota. Our results suggest that as flooding and wet conditions in this region increase, the production of MeHg and its export from terrestrial areas to surface waters will increase also.

Disasters↗
PubMed2007

Influence of flooding, salinity and inundation time on the bioavailability of metals in wetlands.

Controlled flooding of lowlands is considered as a potential water management strategy to minimize the risk of flooding of inhabited areas during high water periods. However, due to industrial activities, river water, sediments and soils are often contaminated with metals which may have adverse effects on the ecosystem's structure and functioning. Additionally, salinity may greatly affect the bioavailability and toxicity of metals present or imported into these systems. The effect of contaminated soils under different flooding and salinity exposure scenarios on the growth, reproduction and metal accumulation in the oligochaete Tubifex tubifex (Müller, 1774) were examined. In these bioassays metal contaminated soils were flooded with water of different salinities (0 and 3 psu), and tested after 0, 6 and 12 months of permanent inundation. We indeed found that inundation time had significant decreasing effects on Cu and Zn accumulation; although initial accumulation of Cu and Zn was higher in the previously unflooded soil at the start of the flooding treatment, these differences seem to disappear after 6 months of permanent inundation. Moreover, the complex interaction between substrate type and salinity suggests that redox potential is probably of major importance.

Animals↗
PubMedDate not supplied

Post-flood--infectious diseases in Mozambique.

INTRODUCTION: The types of medical care required during a disaster are determined by variables such as the cycle and nature of the disaster. Following a flood, there exists the potential for transmission of water-borne diseases and for increased levels of endemic illnesses such as vector-borne diseases. Therefore, consideration of the situation of infectious diseases must be addressed when providing relief. The Japan Disaster Relief (JDR) Medical Team was sent to Mozambique where a flood disaster occurred during January to March 2000. The team operated in the Hokwe area of the State of Gaza, in the mid-south of Mozambique where damage was the greatest. METHODS: An epidemiological study was conducted. Information was collected from medical records by abstracting data at local medical facilities, interviewing in habitants and evacuees, and conducting analyses of water. RESULTS: A total of 2,611 patients received medical care during the nine days. Infectious diseases were detected in 85% of all of patients, predominantly malaria, respiratory infectious diseases, and diarrhea. There was no outbreak of cholera or dysentery. Self-reports of the level of health decreased among the flood victims after the event. The incidence of malaria increased by four to five times over non-disaster periods, and the quality of drinking water deteriorated after the event. CONCLUSIONS: Both the number of patients and the incidence of endemic infectious diseases, such as malaria and diarrhea, increased following the flood. Also, there was a heightening of risk factors for infectious diseases such as an increase in population, deterioration of physical strength due to the shortage of food and the temporary living conditions for safety purposes, and turbid degeneration of drinking water. These findings support the hypotheses that there exists the potential for the increased transmission of water borne diseases and that there occurs increased levels of endemic illnesses during the post-flood period.

Adolescent↗
PubMedDate not supplied

Emergency health surveillance after severe flooding in Louisiana, 1995.

INTRODUCTION: In disaster situations, timely surveillance systems that provide illness, injury, and mortality information to public health officials and hospitals are essential for planning and evaluating interventions. OBJECTIVES: To describe flood surveillance methodology, the impact of the event on hospitals, and the number of daily patient visits due to selected illnesses and injuries before, during, and after severe flooding in southeastern Louisiana in May 1995. METHODS: Survey of disaster-area hospitals regarding flood impact. Emergency department surveillance of injuries and illnesses for the week before, the two days during, and the week after the flood. RESULTS: There occurred an increase in the number of persons who drowned or were injured that presented to the moderately affected hospitals during the storm, but there was no increase in visits for gastroenteritis to any group of hospitals. Services were disrupted in more than half of hospitals. The severely affected hospitals had the least variation in the average number of daily visits. None of the drownings were reported by those hospitals that reported severe service disruption. CONCLUSIONS: Data should be collected from all hospitals in or near disaster areas, even if they were not directly affected by the disaster. Public education about the danger of drowning during flash flooding must be improved. The Louisiana experience emphasizes the need for a disaster-preparedness plan for rapid surveillance of illnesses and injuries.

Disasters↗
PubMed2000

Psychosocial resource loss as a mediator of the effects of flood exposure on psychological distress and physical symptoms.

This study used the Conservation of Resources stress model to examine the role of psychosocial resource loss in the aftermath of Midwest flooding. Questionnaires were distributed through churches and completed by 131 adults in flood-affected communities 6 weeks and 6 months after the flood's crest. Frequent psychosocial losses included losses of routine, sense of control, sense of optimism, accomplishing goals, and time with loved ones. Path analysis revealed that psychosocial resource loss mediated the effects of flood exposure on both psychological distress and physical symptoms at 6 months post-flood. The findings suggest that interventions designed to prevent psychosocial resource loss may reduce the long-term effects of disasters.

Adaptation, Psychological↗
PubMed2002

The impact on health and risk factors of the diarrhoea epidemics in the 1998 Bangladesh floods.

The 1998 flood in Bangladesh ravaged approximately 60% of the land and affected over 30 million people. The aim of this study is to examine the impact of the flood on the health of the communities affected and to explore factors associated with episodes of diarrhoea. We conducted structured interviews with 517 people in two districts that had been affected in October 1998, when the flood water level was at its peak. Of the 517 respondents, 98.3% developed health problems or found that existing health problems were exacerbated. Many perceived that their general health condition was 'much worse' (16.9%) or 'worse' (64.3%). The most prevalent condition was fever (63.6%), followed by respiratory problems (46.8%), diarrhoea (44.3%), and skin problems (41.0%). Only 1.0% and 6.7% of the respondents treated water before drinking, by boiling and chlorination, respectively, although water collected from tube-wells (93.2%) and rivers (6.0%) was perceived by 75.0% of the respondents to be contaminated. Factors associated with developing or worsening diarrhoea were as follows; the number of family members, poor economic status, a lack of distribution of water purification tablets, the type of water storage vessels, not putting a lid on the vessel, no use of latrines, perceived change of drinking water, food scarcity, and worries about the future. In logistic regression analysis, men, poor economic status, lack of distribution of water purification tablets, and the type of water storage vessels had a significant association with diarrhoea. The 1998 Bangladesh flood had a substantial impact on the health of communities. Diarrhoea was associated with socioeconomic status, water handling and household sanitation. There ought to be more emphasis on health education in the pre-disaster period in order to empower communities against floods.

Adolescent↗
PubMed1993

Assessment of the mathematical issues involved in measuring the fractional synthesis rate of protein using the flooding dose technique.

1. The fractional synthesis rate of protein is commonly measured by either the constant infusion method or the flooding dose method. The two methods often give different results. 2. An underlying assumption of the traditional flooding dose formula is that the protein synthesis rate is not stimulated by the flooding dose. A new formula for calculation of the fractional synthesis rate is derived with the alternative assumption that the protein synthesis rate is stimulated by an amount proportional to the change in the intracellular concentration of the infused amino acid. The alternative formula is: Fractional synthesis rate = [formula: see text] where EB and EF are the enrichments of bound and free amino acid, respectively (atom per cent excess), and C = 1-(EF/EI), where EI is the enrichment of the infusate. This approach defines the lowest possible value for the fractional synthesis rate. The traditional equation gives a maximal value for the fractional synthesis rate. 3. When data from the literature are considered, the fractional synthesis rate of muscle protein as calculated by the constant infusion technique falls between the values of fractional synthesis rate calculated by the two flooding dose formulae when leucine is the tracer, suggesting that a flooding dose of leucine exerts a stimulatory effect on the rate of protein synthesis, but that the increase is not as great as the increase in the intracellular concentration of leucine.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed2005

Small gas-phase dianions produced by sputtering and gas flooding.

We have extended our previous experiment [Schauer et al., Phys. Rev. Lett. 65, 625 (1990)] where we had produced small gas-phase dianion clusters of C(n) (2-)(n > or =7) by means of sputtering a graphite surface by Cs(+) ion bombardment. Our detection sensitivity for small C(n) (2-) could now be increased by a factor of about 50 for odd n. Nevertheless, a search for the elusive pentamer dianion of C(5) (2-) was not successful. As an upper limit, the sputtered flux of C(5) (2-) must be at least a factor of 5000 lower than that of C(7) (2-), provided that the lifetime of C(5) (2-) is sufficiently long to allow its detection by mass spectrometry. When oxygen gas (flooding with either O(2) or with N(2)O) was supplied to the Cs(+)-bombarded graphite surface, small dianions of OC(n) (2-)(5< or =n < or =14) and O(2)C(7) (2-) were observed in addition to C(n) (2-)(n > or =7). Similarly, Cs(+) sputtering of graphite with simultaneous SF(6) gas flooding produced SC(n) (2-)(6< or =n< or =18). Mixed nitrogen-carbon or fluorine-carbon dianion clusters could not be observed by these means. Attempts to detect mixed metal-fluoride dianions for SF(6) gas flooding of various Cs(+)-bombarded metal surfaces were successful for the case of Zr, where metastable ZrF(6) (2-) was observed. Cs(+) bombardment of a silicon carbide (SiC) wafer produced SiC(n) (2-) (n=6,8,10). When oxygen gas was supplied to the Cs(+)-bombarded SiC surface, small dianions of SiOC(n) (2-) (n=4,6,8) and of SiO(2)C(n) (2-) (n=4,6) as well as a heavier unidentified dianion (at mz=98.5) were observed. For toluene (C(7)H(8)) vapor flooding of a Cs(+)-bombarded graphite surface, several hydrocarbon dianion clusters of C(n)H(m) (2-)(n> or =7) were produced in addition to C(n) (2-)(n> or =7), while smaller C(n)H(m) (2-) with n< or =6 could not be observed. BeC(n) (2-) (n=4,6,8,10), Be(2)C(6) (2-), as well as BeC(8)H(m) (2-) (with m=2 and/or m=1) were observed for toluene vapor flooding of a Cs(+)-bombarded beryllium metal foil. The metastable pentamer (9)Be(12)C(4) (2-) at mz=28.5 was the smallest and lightest dianion molecule that we could detect. The small dianion clusters of SC(n) (2-), OC(n) (2-), BeC(n) (2-), and SiO(m)C(n) (2-) (m=0,1,2) have different abundance patterns. A resemblance exists between the abundance patterns of BeC(n) (2-) and SiC(n) (2-), even though calculated molecular structures of BeC(6) (2-) and SiC(6) (2-) are different. The abundance pattern of SC(n) (2-) is fairly similar to that of C(n) (2-).

Journal Article↗
PubMed1993

An historical review of malaria, kala-azar and filariasis in Bangladesh in relation to the Flood Action Plan.

This paper reviews the evidence of a link between flood control and vector-borne disease in Bengal/Bangladesh. Malaria is historically associated with reduced flooding and embankment construction in the flood plains of Bengal. The land west and south of the Jamuna river was highly malarious in 1916 but is not so today. The lands east of the Jamuna now have a higher, though still small, risk. The reduction in health risk can be attributed to the intensification of land use and human population density. Although there are many mosquito species, the abundance of the former malaria vector appears to have declined as environmental change removed its breeding sites. Visceral leishmaniasis (kala-azar) is a serious disease which is fatal if left untreated. It occurs in irregular, periodic epidemics and is currently increasing in Bangladesh. In the past, malaria and kala-azar were confused and the prevalence of both may have been increased by embankment programmes. Both diseases are unstable and there is insufficient historical information to predict, with certainty, the consequences of environmental change. Reduced flooding accompanied by increased pollution will probably control the malaria vector. More information is needed about the response of the kala-azar vector to flooding. Bancroftian filariasis is non-fatal but causes chronic morbidity. It has had a widespread but usually low prevalence in Bangladesh, with both rural and urban foci. There are few recent data. Increasing organic pollution and drainage obstruction are expected to favour the vector and increase transmission.

Animals↗
PubMed1993

[Use of 15N-labeled lysine for the determination of fractional protein synthesis rates by the flooding method].

The fractional synthesis rates (FSR) for liver, pancreas, small intestine, large intestine, skeleton muscle and whole body protein were estimated with the help of the large dose method of McNurlan et al. (1979) and Garlick et.al (1980) using simultaneously [14C]lysine and [15N]lysine as flooding substances in growing rats. The following results and conclusions can be drawn: In the case of lysine as flooding substance the incorporation time (time from the injection up to killing the animals) can be fixed at 20 minutes. On principle lysine is suitable as flooding substance. [14C]lysine and [15N]lysine can yield identical values for FSR in the same animal. The variation coefficients of the FSR values were 7.3% (4... 12%) using [14C]lysine and 13.8% (9.5... 36%) using [15N]lysine (emission-spectrometry) as flooding substance. Using the mass-spectrometric method for measuring 15N-excess it is possible to obtain the same accuracy of result as in the case of estimation [14C]lysin. The main advantage of using 15N-labelled amino acids as flooding substances is the absence of any radioactivity. Therefore this method is also suitable for farm animals and--in combination with the indolent muscle biopsy--it may be used for men.

Animals↗
PubMed2005

Response and adaptation by plants to flooding stress.

Stress on plants imposed by flooding of the soil and deeper submergence constitutes one of the major abiotic constraints on growth, species' distribution and agricultural productivity. Flooding stress is also a strong driver of adaptive evolution. This has resulted in a wide range of biochemical, molecular and morphological adaptations that sanction growth and reproductive success under episodic or permanently flooded conditions that are highly damaging to the majority of plant species. However, even seemingly poorly adapted species possess some short-term resilience that is important for overall success of these plants in various habitats. The papers contained in this Special Issue address these topics and emphasize molecular, biochemical and developmental processes that impact on flooding tolerance. Most of the articles are based on lectures given to the 8th Conference of the International Society for Plant Anaerobiosis (ISPA), held at the University of Western Australia, Perth, 20-24 September, 2004. Reviews and research papers are presented from the leading laboratories currently working on plant responses to flooding stress.

Acclimatization↗
PubMed2005

Isolation and transcription profiling of low-O2 stress-associated cDNA clones from the flooding-stress-tolerant FR13A rice genotype.

BACKGROUND: and Aims Flooding stress leads to a significant reduction in transcription and translation of genes involved in basal metabolism of plants. However, specific genes are noted to be up-regulated in this response. With the aim of isolating genes that might be specifically involved in flooding stress-tolerance mechanism(s), two subtractive cDNA libraries for the flooding-stress-tolerant rice genotype FR13A have been constructed, namely the single and double subtraction libraries (SSL and DSL, respectively). METHODS: To construct the SSL, mRNAs present in the unstressed control FR13A roots were subtracted from the mRNA pool present in low O2-stressed roots of FR13A rice seedlings. The DSL was constructed from mRNAs isolated from the roots of low O2-stressed FR13A rice seedlings from which pools of low-O2-stress up-regulated mRNAs from Pusa Basmati 1 and constitutively expressed mRNAs from FR13A roots were subtracted. RESULTS: In all, 400 and 606 cDNA clones were obtained from the SSL and DSL, respectively. Global transcript profiling by reverse northern analysis revealed that a large number of clones from these libraries were up-regulated by anaerobic stress. Importantly, selective up-regulated clones showed characteristic cultivar- and tissue-specific expression profiles. Sequencing and annotation of the up-regulated clones revealed that specific signal proteins, hexose transporters, ion channel transporters, RNA-binding proteins and transcription factor proteins possibly play important roles in the response of rice to flooding stress. Also a significant number of novel cDNA clones was noted in these libraries. CONCLUSIONS: It appears that cellular functions such as signalling, sugar and ion transport and transcript stability play an important role in conferring higher flooding tolerance in the FR13A rice type.

DNA, Complementary↗
PubMed2006

The synthetic evaluation model for analysis of flooding hazards.

BACKGROUND: Although many previous epidemiological studies have reported the incidence of diseases, mortality rate and economic losses after natural disasters, none of these studies has been comprehensive enough. Our aim was to establish a synthetic evaluation model (SEM) that can be used to analyze flood hazards. METHODS: Initial evaluation indicators were selected using systematic and literature data analysis. These indicators were tested with single or multiple variable analyses. Final evaluation indicators and their weights were determined using the Delphi procedure. We established a SEM of flood hazards using the hierarchy method and tested the model using jack-knife analysis. RESULTS: The SEM on flood hazards consists of 6 first-rank indicators and 24 second-rank indicators. First-rank indicators were: direct casualties (w = 0.2123), the increased incidence and prevalence rate of the disease (w = 0.1715), excess mortality rate (w = 0.1745), mental injury (w = 0.1038), epidemic focus expansion (w = 0.1572) and economic loss (w = 0.1807). The agreement of the model reached 98.2% tested with the jack-knife analysis. CONCLUSION: A SEM of flood hazards was established with an agreement of 98.2%, which can be used to evaluate the hazards, and assist public health-care workers provide appropriate flood disaster management.

China↗
PubMed2002

Floods in a changing climate: a review.

This paper begins with an analysis of flooding as a natural disaster for which the solutions to the environmental, social and economic problems are essentially those of identifying and overcoming hazards and vulnerability, reducing risk and damaging consequences. Long-term solutions to flooding problems, especially in a changing climate, should be sought in the wider context of developing more sustainable social organization, economics and technology. Then, developments are described of how scientific understanding, supported by practical modelling, is leading to predictions of how human-induced changes to climatic and geological conditions are likely to influence flooding over at least the next 300 years, through their influences on evaporation, precipitation, run-off, wind storm and sea-level rise. Some of the outstanding scientific questions raised by these problems are highlighted, such as the statistical and deterministic prediction of extreme events, the understanding and modelling of mechanisms that operate on varying length- and time-scales, and the complex interactions between biological, ecological and physical problems. Some options for reducing the impact of flooding by new technology include both improved prediction and monitoring with computer models, and remote sensing, flexible and focused warning systems, and permanent and temporary flood-reduction systems.

Climate↗
PubMed2005

Inland and coastal flooding: developments in prediction and prevention.

We review the scientific and engineering understanding of various types of inland and coastal flooding by considering the different causes and dynamic processes involved, especially in extreme events. Clear progress has been made in the accuracy of numerical modelling of meteorological causes of floods, hydraulics of flood water movement and coastal wind-wave-surge. Probabilistic estimates from ensemble predictions and the simultaneous use of several models are recent techniques in meteorological prediction that could be considered for hydraulic and oceanographic modelling. The contribution of remotely sensed data from aircraft and satellites is also considered. The need to compare and combine statistical and computational modelling methodologies for long range forecasts and extreme events is emphasized, because this has become possible with the aid of kilometre scale computations and network grid facilities to simulate and analyse time-series and extreme events. It is noted that despite the adverse effects of climatic trends on flooding, appropriate planning of rapidly growing urban areas could mitigate some of the worst effects. However, resources for flood prevention, including research, have to be considered in relation to those for other natural disasters. Policies have to be relevant to the differing geology, meteorology and cultures of the countries affected.

Computer Simulation↗