127 research outputs found
Groundwater Recharge, Evapotranspiration and Surface Runoff Estimation Using WetSpass Modeling Method in Illala Catchment, Northern Ethiopia
Hydrometeorological information is important in planning and management of natural resources. The northern Ethiopia in general and Illala sub-basin in particular is lacking reliable information with regard to groundwater recharge, evapotranspiration and surface runoff. The main objective of the study is to estimate the distributed groundwater recharge, surface runoff and evapotranspiration amount of Illala sub basin using WetSpass modeling method. Long term mean hydrometeorological data and physical characteristics of the catchment such as land use/land cover, soil type, topography, groundwater level and slope are used as an input to the model. The mean annual groundwater recharge, evapotranspiration and runoff were found to be 66, 440 and 40mm respectively. Accordingly, recharge accounts for 12% of the precipitation while the rest 81% and 7% becomes evapotranspiration and surface runoff respectively. The study area is characterized by low groundwater recharge due to the presence of high evapotranspiration rate associated with high temperature, dry wind, low rainfall and relative humidity though it is a little bit large compared to some parts of the northern Ethiopia.Keywords: Groundwater, WetSpass, Recharge, Illala, Catchment, Tigray, Ethiopi
Modelling the relationship between groundwater depth and NDVI using time series regression with Distributed Lag M
Groundwater plays a key role in hydrological processes, including in determining aboveground vegetal growth characteristics and species distribution. This study aimed at estimating time-series data of Normalized Difference Vegetation Index (NDVI) using groundwater depth as a predictor in two land cover types: grassland and shrubland. The study also investigated the significance of past (lagged) groundwater and NDVI in estimating the current NDVI. Results showed that lagged groundwater depth and vegetation conditions influence the amount of current NDVI. It was also observed that first lags of groundwater depth and NDVI were significant predictors of NDVI in grassland. In addition, first and second lags of NDVI were consistently significant predictors of NDVI in shrubland. This shows the importance of vegetation type when modelling the relationship between groundwater depth and NDVI.Keywords: Groundwater depth; Landsat NDVI; Time-series analysis; Distributed Lag Model
Bio-based liquid fuels as a source of renewable energy: A review
Limited availability of fossil fuels and their associated environmental impact during combustion remains the primary basis for exploring alternative energy sources such as bio-based liquid fuels. Several feedstocks have been used to produce biofuels for different applications with their own pros and cons. For instance, production of bio-fuels using human food chain raw materials such as corn, soy, peanut, and sugarcane are receiving increased criticism due to the competing demands of the same sources for human consumption as food. However, the non-food biomass in the form of agricultural wastes, municipal wastes, waste vegetable oil, and microbial sources are abundantly available that can be utilized as feedstock for production of biofuels. Because of this reason, most biofuels have been produced using the feedstocks that do not affect the food chain. Thus, in this work, the feedstocks of different generation biofuels and their potential yield and associated greenhouse gas emissions, production technologies are critically surveyed. Moreover, the application of biofuels for different purposes are analyzed and compared with their corresponding conventional fuels. The survey also points out the recent issues and challenges of biofuels with their resolution. The future research directions are suggested to sustain biofuel production
Quagga Catshark Halaelurus quagga
The Quagga Catshark (Halaelurus quagga) is a poorly-known catshark recorded from very few
specimens. It has a fragmented known distribution occurring off southwestern India, and around the
Socotra Archipelago (Yemen).
This small shark (reaching ~37 cm total length) occurs at depths of 54-300 m, but appears to be a mostly
deep-water species. The development of intense deep-sea bottom trawl fishing off southwestern India
where the species is most likely to be taken as bycatch is a concern. Its small size means that it would be
discarded at sea, but survivorship would be low. There are currently no deep-sea fishing activities
around the Socotra Archipelago. Declines off southwestern India are suspected, but the extent to which
fishing is affecting the species there is not known. Despite some concern, the species is assessed as Data
Deficient, with a urgent need to assess bycatch rates in the Indian deep-sea shrimp trawl fishery
Development of novel clinical examination scales for the measurement of disease severity in Creutzfeldt-Jakob disease
OBJECTIVE: To use a robust statistical methodology to develop and validate clinical rating scales quantifying longitudinal motor and cognitive dysfunction in sporadic Creutzfeldt-Jakob disease (sCJD) at the bedside. METHODS: Rasch analysis was used to iteratively construct interval scales measuring composite cognitive and motor dysfunction from pooled bedside neurocognitive examinations collected as part of the prospective National Prion Monitoring Cohort study, October 2008-December 2016.A longitudinal clinical examination dataset constructed from 528 patients with sCJD, comprising 1030 Motor Scale and 757 Cognitive Scale scores over 130 patient-years of study, was used to demonstrate scale utility. RESULTS: The Rasch-derived Motor Scale consists of 8 items, including assessments reliant on pyramidal, extrapyramidal and cerebellar systems. The Cognitive Scale comprises 6 items, and includes measures of executive function, language, visual perception and memory. Both scales are unidimensional, perform independently of age or gender and have excellent inter-rater reliability. They can be completed in minutes at the bedside, as part of a normal neurocognitive examination. A composite Examination Scale can be derived by averaging both scores. Several scale uses, in measuring longitudinal change, prognosis and phenotypic heterogeneity are illustrated. CONCLUSIONS: These two novel sCJD Motor and Cognitive Scales and the composite Examination Scale should prove useful to objectively measure phenotypic and clinical change in future clinical trials and for patient stratification. This statistical approach can help to overcome obstacles to assessing clinical change in rapidly progressive, multisystem conditions with limited longitudinal follow-up
Smallbelly Catshark Apristurus indicus
The Speckled Catshark (Halaelurus boesemani) is a relatively small (to 48 cm total length), data-poor
catshark. It is known from a limited number of specimens collected from four locations along an ~900
km stretch of Somali coastline. It occurs on continental and insular shelves at depths of 29-91 m. Its
entire distribution has been subject to at least four decades of unregulated commercial benthic
trawling; shelf-occurring catsharks are very susceptible to capture in this fishing gear. The new Somali
Fisheries Law bans benthic trawling, but it is suspected that past declines have already occurred given
the long history of unregulated fishing across its entire range. Furthermore, enforcement of this new
regulation will be a challenge. While specific data are lacking, a population size reduction of 30-50% is
suspected over the past three generations (~45 years) based on actual levels of exploitation (bycatch)
and the species is assessed as Vulnerable A2d. It is of concern that there have been no records since
1991, although it is acknowledged that research and monitoring have been limited in Somalia. Further
investigation of this species is required to accurately define its range, biology, extent of catches in local
fisheries and levels of declines. This assessment should be revisited as soon as this is available
Oman Bullhead Shark Heterodontus omanensis
The Oman Bullhead Shark (Heterodontus omanensis) is known only from central Oman and Pakistan.
Although information is limited on its habitat and ecology, based on known habitats of other
Heterodontus species it likely inhabits a rocky reef substrate, reducing its vulnerability to bottom trawl
fisheries. However, there are trawl caught records of this species, and it is a potential bycatch of
demersal line fisheries operating within its range, although no specific information is currently available.
More information is required on its biology, abundance and full range, capture in fisheries and
population trends. While the limited number of individuals recorded to date may suggest this species
occurs in areas not fished heavily, there is currently insufficient information at assess how fisheries in
the region are interacting with the species, and as such it is assessed as Data Deficient
Speckled Catshark Halaelurus boesemani
The Speckled Catshark (Halaelurus boesemani) is a relatively small (to 48 cm total length), data-poor
catshark. It is known from a limited number of specimens collected from four locations along an ~900
km stretch of Somali coastline. It occurs on continental and insular shelves at depths of 29-91 m. Its
entire distribution has been subject to at least four decades of unregulated commercial benthic
trawling; shelf-occurring catsharks are very susceptible to capture in this fishing gear. The new Somali
Fisheries Law bans benthic trawling, but it is suspected that past declines have already occurred given
the long history of unregulated fishing across its entire range. Furthermore, enforcement of this new
regulation will be a challenge. While specific data are lacking, a population size reduction of 30-50% is
suspected over the past three generations (~45 years) based on actual levels of exploitation (bycatch)
and the species is assessed as Vulnerable A2d. It is of concern that there have been no records since
1991, although it is acknowledged that research and monitoring have been limited in Somalia. Further
investigation of this species is required to accurately define its range, biology, extent of catches in local
fisheries and levels of declines. This assessment should be revisited as soon as this is available
Variation for Agro-Morphological Traits among Kabuli Chickpea (Cicer arietinum L.) Genotypes
The objectives of this study were to evaluate genetic variation among kabuli chickpea genotypes and to
determine the relationships among agronomic traits with seed yield. Field experiments were conducted during
the long and short rain seasons of 2013 using alpha lattice design in triplicate. Data on agro-morphological traits
were recorded using descriptors for chickpea and analysed using SAS 2013 and Genstat 2014. There were highly
significant (p < 0.001) variations among genotypes and genotype by environment interactions for all studied
traits. The top five high yielding genotypes were ICCV 05315, ICC 13461, ICCV 07313, ICC 13764 and ICCV
00302. Genotypes ranking for most agronomic traits varied across environments which indicated a crossover
type of genotype by environment interactions. Evaluated genotypes were polymorphic for six qualitative traits.
Seed yield ha-1 was positively and significantly (p < 0.05) correlated with biomass yield ha-1, pods plant-1, plant
canopy width and secondary branches plant-1. These characters could be used for indirect selection of high
yielding genotypes. The first principal component explained 57% of the total variation and was associated with
days to 50% flowering and podding, plant canopy width, plant height, number of primary and secondary
branches plant-1, days to 75% maturity, number of pods plant-1 and biomass yield ha-1 as positive contributors.
The documented information on genetic variation and association of agronomic traits with seed yield can be
exploited to devise suitable breeding strategies and chickpea germplasm conservation
Ctenacis fehlmanni, Harlequin Catshark
The Harlequin Catshark (Ctenacis fehlmanni) is a small (to at least 52 cm total length) outer shelf
dwelling catshark, known from 70 m to over 300 m depth off Somalia in the Arabian Sea. Little is known
about the biology or ecology of this species. This poorly-known deep-sea shark occurs in an area where
no deep-sea trawling fisheries take place and there are no other known threats. Due to the depth of
occurrence and the lack of deep-sea fisheries in the region the species is assessed as Least Concern
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