178 research outputs found
Hilbert series of modules over Lie algebroids
We consider modules over Lie algebroids which are of
finite type over a local noetherian ring . Using ideals such
that and the length we can define in a natural way the Hilbert series of
with respect to the defining ideal . This notion is in particular studied
for modules over the Lie algebroid of -linear derivations that preserve an ideal , for example when
, the ring of convergent power series. Hilbert series over
Stanley-Reisner rings are also considered.Comment: 42 pages. This is a substantial revision of the previous versio
Using Edge-induced and Vertex-induced Subhypergraph Polynomials
For a hypergraph , we consider the edge-induced and
vertex-induced subhypergraph polynomials and study their relation. We use this
relation to prove that both polynomials are reconstructible, and to prove a
theorem relating the Hilbert series of the Stanley-Reisner ring of the
independent complex of and the edge-induced subhypergraph
polynomial. We also consider reconstruction of some algebraic invariants of
.Comment: 9 page
SOLID STATE PHOTOELECTROCHEMICAL CELL BASED ON DYE SENSITIZED TiO2 AND POLYMER ELECTROLYTE COMPLEXED WITH I3¯/I¯
A solid state photoelectrochemical solar energy conversion device based on nanocrystalline-TiO2 sensitized with Di-Tetrabutylammoniumcis-bis(isothiocyanato)bis(2,2’-bipyridyl-4,4’-dicarboxylato)-ruthenium(II) (N719) dye has been constructed and characterized. The current density–voltage characteristics in the dark and under white light illumination and action spectra under monochromatic illuminations have been studied. The following device parameters were obtained when the potential is scanned: an open circuit voltage of 762 mV and a short circuit current density of 33 μAcm-2 at light intensity of 100 mWcm-2; the IPCE percentage obtained was 1.7% at 330 nm. The dependence of the short-circuit current density and an open circuit voltage on the incident light intensity and illumination time have also been studied. The results of time dependence study show that the steady state Jsc and Voc values are consistent with those obtained from the J–V curve
Poincaré series of monomial rings with minimal Taylor resolution
We give a comparison between the Poincaré series of two monomial rings: R = A/I and R_q = A/I_q where I_q is a monomial ideal generated by the q’th power of monomial generators of I. We compute the Poincaré series for a new class of monomial ideals with minimal Taylor resolution. We also discuss the structure a monomial ring with minimal Taylor resolution where the ideal is generated by quadratic monomials
Characterization of Mosquito Breeding Sites in and in the Vicinity of Tigray Microdams
BACKGROUND: Malaria vector control in Ethiopia has a history of more than 50 years, but malaria remains a major cause of morbidity and mortality in Ethiopia. Thus, targeting the control program on the larval stage is of paramount importance. This study aimed to characterize the aquatic habitats of vector mosquito larvae associated with micro-dams. METHODS: Cross-sectional larval survey was conducted on six micro-dams in Tigray, Northern Ethiopia in 2005/06. The study area on each dam was divided into eight zones. Immature stages of mosquitoes were collected using standard dippers. The physico-chemical characteristics of the aquatic habitats were measured onsite. RESULTS: A total of 301 aquatic habitats were surveyed for mosquito larvae; in 32.56% (n=301) only Anopheles, in 27.91% only Culex, both genera were found mixed in 21.59% and no mosquito larvae were found in 17.94%. The findings depicted that dissolved oxygen (r = 0.34, p =0.04), pH (r = 0.35, p =0.03), conductivity (r = 0.36, p =0.03), vegetation (F = 3.54, p =0.002), microhabitat (F = 2.65, p =0.04), fauna and bottom surface of the water body were positively associated and important in explaining the presence and abundance of Culex. On the other hand, dissolved oxygen (r = 0.39, p =0.02), pH (r = 0.42, p =0.008), vegetation (F = 5.6, p =0.000), water transparency (F = 2.72, p =0.00), rainfall (F = 2.22, p = 0.027) and fauna were positively associated and important in explaining the presence and abundance of Anopheles. CONCLUSION: The findings of this study suggest that both biotic (vegetation and fauna) and abiotic (chemical and physical) factors play a significant role in larvae’s habitat preference in both Culex and Anopheles.
KEYWORDS: Anopheles, breeding, characteristics, Culex, larvae, mosquito, Northern Ethiopi
Two-way Interactions Between Bioenergy Croppng Systems and Water Resources
Understanding the two-way interactions between bioenergy cropping systems and water resources is imperative for the successful deployment of these crops in the US Southern Great Plains (SGP); however, such information is limited in the region. This study was conducted (i) to quantify and compare water budget components under switchgrass, biomass sorghum, and mixed perennial grasses in Oklahoma; (ii) to partition evapotranspiration (ET) components and determine the water use efficiency (WUE) of these cropping systems; and (iii) to model watershed scale hydrological impacts of switchgrass biomass production on grasslands versus marginal croplands. Soil water content was measured regularly from 2011 to 2013 at two locations, and ET was estimated using the soil water balance approach. The ET was partitioned by measuring canopy interception and estimating soil evaporation. Transpiration was calculated as the difference. WUE was estimated as the ratio of above-ground biomass produced to ET and transpiration. The Soil and Water Assessment Tool (SWAT) was used for the watershed-scale study. The result showed that soil water depletion occurred mainly above 2 m under all crops considered. The total growing season soil water depletion varied from 4 to 287 mm depending on the initial soil water content and growing season rainfall. Crop year ET also varied from 493 to 846 mm and was greater for perennial grasses than biomass sorghum except during a wet year when the two systems had similar ET. Transpiration was the largest component of growing season ET for all cropping systems. The non-productive loss portion of ET was greater for biomass sorghum than switchgrass, but biomass sorghum had higher WUE than switchgrass, which compensated for its higher non-productive losses. SWAT simulated average switchgrass yield of 12 Mg ha-1 on grasslands and marginal croplands along with an increase in ET and reduction in streamflow relative to the baseline scenario. The hydrologic cost per ton of biomass production is predicted to be approximately five times greater for grasslands than marginal croplands. In the SGP, rainfed bioenergy production system based on biomass sorghum may consume less water per unit land area than systems based on perennial grasses, but the non-productive losses and other ecosystem services need to be considered. From a hydrologic perspective, it may be preferable to convert marginal croplands to switchgrass production rather than converting existing grasslands.Soil Science (PhD
Aquifers Characterization and Productivity in Ellala Catchment, Tigray, Northern Ethiopia
This paper assesses the aquifer characteristics and productivity nature of different rocks and sediments using geological and hydrogeological methods in Ellala catchment (296.5km2) in Tigray, northern Ethiopia. The catchment consists of limestone (29.91%), intercalation of limestone-shale-marl (27.90%), dolerite dykes and sills (21.85%) and recent sediments (20.33%). Compared to rocks, the sediment due to lack of both extensive areal coverage and thickness, its water-bearing capability is almost negligible. Aquifers developed in the different rocks are mainly due to secondary processes such as weathering, fracturing and karstification. The degree of variations in the groundwater productivity is mainly linked with the variations in the effect of these processes in the respective rock. Hydrodynamic analyses of the aquifers reveal that in the limestone aquifer hydraulic conductivity is ranging from 0.046 to 4.65 m/day with a mean value of 1.44 m/day and transmissivity is ranging from 2.38 to 93.02 m2/day with a mean value of 32.58 m2/day; in the intercalated limestone-shale-marl aquifer hydraulic conductivity is ranging from 0.87 to 70.13 m/day with a mean value of 10.11 m/day and transmissivity is ranging from 17.88 to 645.7 m2/day with a mean value of 163.41 m2/day; and in the dolerite aquifer hydraulic conductivity is ranging from 1.67 to 108.86 m/day with a mean value of 59.32 m/day and transmissivity is ranging from 57.63 to 307 m2/day with a mean value of 142.71 m2/day. Based on these determined transmissivity values of different aquifers and geomorphological setup of the catchment, the potentiality degree of the aquifers of the catchment range from moderate to negligible. The negligible potentiality aquifer is found covering steep slopes and topographically high areas, whereas aquifers that have moderate to weak degree of potentiality are found occupying flat to rugged topography of the catchment.Keywords: Groundwater, Aquifer, Ellala catchment, Hydraulic conductivity, Transmissivity, Ethiopia
Performance of crossbred dairy cows suitable for smallholder production systems at Holetta Agricultural Research Centre
The present study was undertaken to investigate productive and reproductive performances of F1 crossbred cows to produce and develop improved dairy cattle breed at on station and back up the on farm crossbreeding program at Holetta Research Center (HRC). One hundred fifty three F1 crossbred heifers were used to study growth performances and 111 worldwide sire (WWS) and 42 Kality (NAIC) sire records were used to analyze the data. A total of 802 milk records out of which 711 from worldwide sire (WWS) milk records and 91 from Kality (NAIC) bulls’ milk records were used to analyze the milk production performances. Least squares means of growth traits in this study birth weight (BWT), average daily gain (ADG) of crossbred heifers was 24.83 ± 2.33 kg and ADG ranges from 0.437 ± 0.01 to 0.546 ± 0.02 kg respectively. Least squares mean for age at first service (AFS), age at first calving (AFC), calving interval (CI), and number of service per conception (SPC) were 26.4±0.8 months, 35.7±o.81 months, 500.32±2.92 to 395.64 ± 4.9 days, and 1.2 ± 0.2 to 2.37 ± 0.05 services, respectively. Lactation milk yield (LMY) obtained from this result reflected progressive trend from 1st to 5th parity (1874.65 ± 67.7 to 2582.69 ± 111.2 kg) and started declining thereafter. The declining trend observed after the 5th parity is the normal biological phenomenon from dairy cows under normal conditions. The improvement gained from this result is the outcome of the of management procedures and practices followed which have accounted for 15.5 % of early calving of young heifers and 21 % in milk yield increments made from Frisian Boran (FB) crossbred cows at HARC. The overall observed growth, reproductive and milk yield performance of FB crossbred dairy cows at HARC has shown progressively significant improvement. Thus in order to continue with the crossbreeding for development of F1 50% crossbred dairy cows to maintain the on station and backup the on farm breeding activity there is a need to do intensive and proper performance evaluation based on defined breeding objectives. Culling procedures to avoid milking cows beyond the 5th parity is important. Research centers have to put maximum efforts to improve routine management activities to maintain performance evaluated animals at the centers at all levels.Keywords: Crossbred, heifers, dairy cows, performanc
Effect of Salt Stresses on Seed Germination and Early Seedling Growth of Camelina sativa L.
Camelina sativa is a promising low-input, high yielding biodiesel crop that can be suitable to grow on marginal lands and is a good source of omega-3 fatty acids. But, saltiness is an overall issue of agriculture that constrains the germination, development and productivity of plant because of osmotic and ionic poisonous quality impacts. The aim of this study was to assess the effect of salinity (NaCl and KCl) on germination and early seedling growth of Camelina sativa. Camelina sativa seeds were obtained from agricultural research sector of Wachemo University. In the laboratory, six salinity levels of NaCl and KCl (0, 1, 2, 3, 4 and 5 g/L) were prepared and arranged in completely randomized design with four replications. The result of the study revealed that C. sativa seedlings were differ significantly (p<0.05) on speed of germination, germination percentage, germination index, shoot length, root length, vigor index, root shoot ratio and seedling fresh weight, relative injury rates of NaCl and KCl, shoot height reduction and root height reduction. However, there is no significant effect between salt type versus salinity level and salt type in all parameters tested except shoot length and shoot height reduction at 5% significant level. The increase in both salts (NaCl and KCl) concentration in culture medium causes a significant decreases in speed of germination, germination percentage, germination index, shoot length, root length, vigor index, root shoot ratio and seedling fresh weight of the salt treated C. sativa seeds as compared with the control (C. sativa seeds watered with distilled water). Similarly, relative injury rates NaCl and KCl shoot height reduction, root height reduction were highly increased as salinity level increases. Generally, as the concentration of NaCl and KCl was increased the overall germination and early seedling performance of C. sativa decreased. The effect of salinity on physiology, molecular and biochemical of properties of C. sativa should be studied.
Keywords: Camelina sativa, Salinity effect, NaCl, KCl, Seed germination, Seedling growth
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