The water hyacinth problem and the biological control option in the highland lake region of the upper Nile basin: Uganda's experience

The rapid proliferation and extensive spread of water hyacinth Eichhornia crassipes (Mart) Solms in the highland lakes of the Nile Basin within less than 15 years of introduction into the basin in the 1980s pauses potential environmental and social economic menace if the noxious weed is not controlled soon. The water weed has spread all round Lake Victoria and, in Uganda where infes tation is mos t severe, water hyacinth estimated at 1,330,000 ton smothers over 2,000 ha of the lakeshore (August,1994). Lake Kyoga which already constantly supplies River Nile with the weed is infested with over 570 ha, while over 80% of the river course in Uganda is fringed on either side with an average width of about 5m of water hyacinth. As the impact of infestation with water hyacinth on water quality and availability, transportation by water, fishing activities, fisheries ecology, hydro-power generation etc becomes clear in Uganda, serious discussion is under way on how to control and manage the noxious weed. This paper pauses some of the questions being asked regarding the possible application of mechanical and chemical means to control the water weed.Uganda has already initiated the use of biological control of water hyacinth on Lake Kyoga with a strategy to use two weevils namely Neochetinabruchi and Neochetina eichhorniae. The strategy to build capacity and infrastructure for mass multiplication and deployment of biological control of the weevils in the field developed in Uganda by the Fisheries Research Insti tu te (FIRI) and the Namulonge Agricultural and Animal production Research Insti tute (NAARI) is proposed in outline for evaluation. Plans to deploy this strategy on lake Kyoga are under way

Some characteristics of the fish fauna of a dam in the Lake Victoria region of Tanzania including the effects of multispecific stocking with tilapia species

Malya dam had been stocked with several species of Tilapia. However all but the species endemic to the region, T esculentus, made only marginal contributions to the fishery. T. zilli particularly had failed to establish itself, probably because its niche had been previously filled by T. rendalii. Planktivorou Tilapia species predominate in Malya dam but in smaller dams in the region herbivoorous tilapia are relatively more abundant. Six non-cichlid species and one of Haplochromis were found in the dam. Tilapia esculenta the most economically important species, was estimated to grow within 9-10 cm first year and 16-18 cm second year. The largest, specimen caught was 30.5 cm and the smallest mature individual 19 cm. The fish of the dam grew more slowly and matured at a smaller size than those of the same species in Lake Victoria The biological pattern of T. esculenta in Malya dam was similar to that of this species in Lake Victoria.

Observations on the biology of Nothobranchius guentheri (Pfeffer) (Cyprinodontidae), an annual fish from the coastal region of East Africa

Nothobranchius guntheri is found in seasonal pools and streams in the coastal region of Tanzania. A population recurring annually in a pond near Kilosa has been studied. Growth in length was rapid and maximum mean lengths were attained within 11-12 and 7-8 weeks of hatching by males and females respectively. Males grew larger and exhibited wider variation in length than females. N. guentheri shows clear sexual dichromatism. No significant inequality in the sex ratio was found. Females with ripe eggs were found 7-8 weeks after hatching. Spawning continued throughout adult life and fecundity increased markedly with increasing length. In laboratory aquaria, aggressiveness between adult males was noted and females were actively driven on to the substratum preparatory to spawning. The diet of the fish pond consisted chiefly of aquatic and terrestrial insects, of which midge larvae and pupae were the most common. N. guentheri is exploited by man in the aquarist trade and for the biological control of mosquitoes. An extended redescription of the species is appended which includes N. melanospilus (Pfeffer) as a synonym.

A note on recent advances in the genetic characterization of tilapia stocks in Lake Victoria region

Oreochromis esculenta, the original "ngege" is virtually extinct in Lake Victoria, and is limited to satellite lakes and reservoirs in the greater Lake Victoria region. Oreochromis variabilis can still be found in Lake Victoria and some satellite lakes in the Kyoga System, but in small numbers and only at a few localities (WANDERA and KAUFMAN, unpub. data). Little is known about the influence that species translocations have had on the genetic structure of these crucial fishery species, and even the source of the parent stocks for the introductions remain obscure. Genetic variability was examined within and among allopatric populations of three species in the tilapiine genus Oreochromis: O. esculentus (endemic to Lakes Victoria and Kyoga), and two exotic species introduced to Lake Victoria in the late 1950's to supplement the failing fisheries for native tilapiines, O. niloticus and O. leucostictus.

The potential of community fish refuges (CFRs) in rice field agro-ecosystems for improving food and nutrition security in the Tonle Sap region

The fisheries sector in Cambodia contributes 8%–12% to national GDP and 25% - 30% to agricultural GDP, with an estimated 4.5 million people involved in fishing and associated trades. Fish and other aquatic animals are important food sources, contributing an estimated national average of 60% - 70% of total animal protein intake. Of the 2013 total fish production, 550,000 metric tons were harvested from freshwater habitats, of which rice field fisheries and small-scale family fisheries contributed approximately 20%. The productivity and value of rice field fisheries to households in rural Cambodia has been highlighted in a number of previous studies. The Fisheries Administration of the Ministry of Agriculture, Forestry and Fisheries plans to increase productivity from rice field fisheries and aquaculture at an annual rate of 15% to maintain supply for a growing population. This report draws mainly on the baseline and monitoring data from the Rice Field Fisheries Enhancement Project (RFFEP) during its implementation between 2012 and 2014. Reference is also made to the Fish on Farms project to highlight the relative contribution of fish from small-scale aquaculture compared to wild-caught fish.

Compressive failure of finite size unidirectional composite laminates with a region of fibre waviness

The compressive behaviour of finite unidirectional composites with a region of misaligned reinforcement is investigated via finite element analyses. Models with and without fibre bending stiffness are compared, confirming that compressive strength is accurately predicted without modelling fibre bending stiffness for real composite components which typically have waviness defects of several millimetres wavelength. Various defect parameters are investigated. Results confirm the well-known sensitivity of compressive strength to misalignment angle, and also show that compressive strength falls rapidly with the proportion of laminate width covered by the wavy region. A simple empirical equation is proposed to model the effect of a single patch of waviness in finite specimens. Other parameters such as length and position of the wavy region are found to have a smaller effect on compressive strength. The modelling approach is finally adapted to model distributed waviness and thus determine the compressive strength of composites with realistic waviness defects. © 2011 Elsevier Ltd. All rights reserved.

Spatio-temporal clustering of probabilistic region trajectories

We propose a novel model for the spatio-temporal clustering of trajectories based on motion, which applies to challenging street-view video sequences of pedestrians captured by a mobile camera. A key contribution of our work is the introduction of novel probabilistic region trajectories, motivated by the non-repeatability of segmentation of frames in a video sequence. Hierarchical image segments are obtained by using a state-of-the-art hierarchical segmentation algorithm, and connected from adjacent frames in a directed acyclic graph. The region trajectories and measures of confidence are extracted from this graph using a dynamic programming-based optimisation. Our second main contribution is a Bayesian framework with a twofold goal: to learn the optimal, in a maximum likelihood sense, Random Forests classifier of motion patterns based on video features, and construct a unique graph from region trajectories of different frames, lengths and hierarchical levels. Finally, we demonstrate the use of Isomap for effective spatio-temporal clustering of the region trajectories of pedestrians. We support our claims with experimental results on new and existing challenging video sequences. © 2011 IEEE.

Bird and mammal conservation in Gaoligongshan Region and Jingdong County, Yunnan, China: patterns of species richness and nature reserves

Elevational and latitudinal patterns of species richness for birds and mammals were compared with human population density in relation to nature reserve designation in two areas of Yunnan Province, China. Results suggest that species richness is not the same for the two areas. In Gaoligongshan Region, species richness is inversely correlated with elevation and altitude, while reserve designation is positively correlated with elevation and latitude. In Jingdong County, reserve designations are positively correlated with elevation, but species richness shows no clear trends. In general, the present situation is strongly influenced by human activities. It appears that reserve designation is mismatched with species richness in Gaoligongshan Region, while there is a better fit between the two in Jingdong County. In both areas, however, it appeared that reserves were located primarily in order to reduce conflict with humans rather than to maximize conservation of biodiversity, probably because humans were responsible for forest-especially primary forest-destruction and degradation in the low-lying areas.

Secondary structure of yeast genomic downstream region and polyadenylation signals

Polyadenylation of 3 ' -forming in eukaryote concerns three elements located in precursor mRNA downstream region: efficiency element (EE), position element (PE) and the actual site for cleavage and polyadenylation. Several base sequences of EE and PE have

High prevalence of HIV-1 and hepatitis C virus coinfection among injection drug users in the southeastern region of Yunnan, China

The southeastern region of Yunnan province is a key site for drug trafficking and HIV-1 infection spread from the west of Yunnan and Laos to southeastern China. To investigate the prevalence of HIV-1 infection and hepatitis C virus (HCV) coinfection among injection drug users (IDUs) in southeastern Yunnan, three cohorts of 285 addicts, including 242 IDUs and 43 oral drug users, living in the cities of Gejiu and Kaiyuan and the county of Yanshan were studied. HIV-1 and HCV infections were detected by enzyme-linked immunosorbent assay and/or polymerase chain reaction. Data on the age, sex, risk behavior, drug use history, employment, ethnic background, and marriage status were obtained by interview. The overall prevalence of HIV-1 infection was 71.9%. The rate of HCV coinfection among 138 HIV-1-infected IDUs was 99.3%. Most HIV-infected IDUs were 20 to 35 years old (86.7%) and were ethnic Han (75.9%), suggesting that the epidemic in Yunnan is no longer confined to non-Han ethnic minorities, HIV prevalence in female IDUs (81.2%) was significantly higher than in male IDUs (68.2%) (p <.05). The prevalence of HIV infection reached 68.4% after 1 year of injection drug use. Needle/syringe sharing is the major high risk factor for the spread of HIV-1 and HCV infections. Large-scale educational campaigns are urgently needed to reduce the spread of HIV and HCV infection in these regions.

Shape vs. volume: Invariant shape descriptors for 3D region of interest characterization in MRI

We propose a new approach for quantifying regions of interest (ROIs) in medical image data. Rotationally invariant shape descriptors (ISDs) were applied to 3D brain regions extracted from MRI scans of 5 Parkinson's patients and 10 control subjects. We concentrated on the thalamus and the caudate nucleus since prior studies have suggested they are affected in Parkinson's disease (PD). In the caudate, both the ISD and volumetric analyses found significant differences between control and PD subjects. The ISD analysis however revealed additional differences between the left and right caudate nuclei in both control and PD subjects. In the thalamus, the volumetric analysis showed significant differences between PD and control subjects, while ISD analysis found significant differences between the left and right thalami in control subjects but not in PD patients, implying disease-induced shape changes. These results suggest that employing ISDs for ROI characterization both complements and extends traditional volumetric analyses. © 2006 IEEE.