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Search Results: 1 - 10 of 3534 matches for " Rebecca Godfrey "
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Nectar Meals of a Mosquito-Specialist Spider
Josiah O. Kuja,Robert R. Jackson,Godfrey O. Sune,Rebecca N. H. Karanja
Psyche , 2012, DOI: 10.1155/2012/898721
Development of a Web-Based Geographic Information System for Mass Land Valuation: A Case Study of Westlands Constituency, Nairobi County  [PDF]
Godfrey Ludiema, Godfrey Makokha, Moses Murimi Ngigi
Journal of Geographic Information System (JGIS) , 2018, DOI: 10.4236/jgis.2018.103015
Abstract: The development of a web-based Geographic Information System for mass property valuation was the main focus of this research. The developed web GIS allows effective dissemination, extraction and analysis of mass land valuation information over the Internet. It also allows for automation of the mass property valuation process by compiling a centralized mass valuation roll database. The Westlands Constituency, one of the administrative regions of the Nairobi City County was used as a case study. The research focused on automation of the mass property valuation roll by creating a centralized database that is accessible by all users on the web-based GIS portal. This was done by customizing and integrating a web-based GIS system based on open source QuantumGIS, GeoServer and PostgreSQL/PostGIS as a relational database. Leaflets APIs were used for the development of an interactive and friendly geographic user interface. The developed system enables users to view and interact with the spatial data. This improves the efficiency and effectiveness of the decision making process and data sharing for mass property valuation and optimal property taxation purposes.
Nectar Meals of a Mosquito-Specialist Spider
Josiah O. Kuja,Robert R. Jackson,Godfrey O. Sune,Rebecca N. H. Karanja,Zipporah O. Lagat,Georgina E. Carvell
Psyche , 2012, DOI: 10.1155/2012/898721
Abstract: Evarcha culicivora, an East African jumping spider, is known for feeding indirectly on vertebrate blood by actively choosing blood-carrying mosquitoes as prey. Using cold-anthrone tests to detect fructose, we demonstrate that E. culicivora also feeds on nectar. Field-collected individuals, found on the plant Lantana camara, tested positive for plant sugar (fructose). In the laboratory, E. culicivora tested positive for fructose after being kept with L. camara or one of another ten plant species (Aloe vera, Clerodendron magnifica, Hamelia patens, Lantana montevideo, Leonotis nepetaefolia, Parthenium hysterophorus, Ricinus communis, Senna didymobotrya, Striga asiatica, and Verbena trivernia). Our findings demonstrate that E. culicivora acquires fructose from its natural diet and can ingest fructose directly from plant nectaries. However, experiments in the laboratory also show that E. culicivora can obtain fructose indirectly by feeding on prey that have fed on fructose, implying a need to consider this possibility when field-collected spiders test positive for fructose. In laboratory tests, 53.5% of 1,215 small juveniles, but only 3.4% of 622 adult E. culicivora, left with plants for 24 hours, were positive for fructose. These findings, along with the field data, suggest that fructose is especially important for early-instar juveniles of E. culicivora. 1. Introduction Trophic switching and feeding at more than one trophic level, although often overlooked in the literature on spiders, are common themes in the evolution of arthropods [1, 2]. For example, many predatory heteropterans are known to feed facultatively on plant products [3, 4]. Spiders, however, are typically characterized as being obligate predators. The most striking known exception is Bagheera kiplingi [5], a Central American jumping spider (Salticidae), which is almost entirely herbivorous despite cohabiting with edible ant species (Pseudomyrmex spp.). B. kiplingi feeds primarily on the Beltian bodies (specialized leaf tips) of the ant-acacia (Vachellia spp.), which also dominate the ants' diet [6–8]. Although no other spiders are known to rely as heavily on herbivory as B. kiplingi, many spiders do supplement a predatory diet with nectar taken from the floral or extra-floral nectaries of plants (e.g., [9–12]). Taylor and Pfannenstiel [13] and Chen et al. [14] provided evidence of fructose ingestion by one or more species from each of 13 spider families (Agelenidae, Anyphaenidae, Araneidae, Clubionidae, Corinnidae, Lycosidae, Miturgidae, Nephiliidae, Oxyopidae, Pisauridae, Salticidae,
Using River Altitude Determined from a SRTM DEM to Estimate Groundwater Levels of the Tokwe and Mutirikwi Watersheds in Zimbabwe  [PDF]
David Chikodzi, Godfrey Mutowo
Journal of Geographic Information System (JGIS) , 2016, DOI: 10.4236/jgis.2016.81007
Abstract: Groundwater resources provide most of the domestic water supply in rural Zimbabwe and support poverty reduction through irrigation facilities. Most agricultural and environmental plans need water table depth analysis as an input in designing best management strategies. There are limited direct measurements of groundwater levels in Zimbabwe due to high costs and the limited human expertise. The study is aimed at coming up with a proof of concept that altitude of rivers as determined by an SRTM digital elevation model can be used to estimate the levels of groundwater in parts of Mutirikwi and Runde sub catchments of southern Zimbabwe. The study also maps the groundwater levels of the area as determined by river altitude from the digital elevation model. Firstly, the groundwater levels for nine boreholes are measured. Secondly, the altitude of a river bed nearest to each borehole site is extracted from a digital elevation model. Finally, the Spearman’s correlation coefficient is used to determine the nature and strength of the relationship between the two variables. Linear regression analysis was also used to obtain the predictive equation of the relationship and its coefficient of determination. After the relationship between groundwater and river altitude is established, 9 new random points of river altitude are generated across the study area interpolated using kriging interpolation to give the estimated altitude of river altitude. The altitude of groundwater is then determined by running the predictive equation Y = 0.8736 * X + 0.852 obtained from regression analysis. The depth to groundwater level of area is obtained by subtracting the determined groundwater altitude from the SRTM DEM. The results show strong positive and statistically significant (ρ= 0.000,α= 0.01) correlation coefficient of 0.971 between measured groundwater levels and altitude of rivers. The regression model shows a coefficient of determination (r2) of 0.975. The research therefore determines that altitude of rivers and use of geostatistics can
Pricing Currency Call Options  [PDF]
Rebecca Abraham
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.811148
Abstract: This paper presents a theoretical model to price foreign currency call options. Currency options are employed in international trade to reduce the risk of loss due to the reduction of revenues obtained in depreciating foreign currency for an exporter, or the escalation of expense from appreciating foreign currency for an importer. Other users include banks and hedge funds who engage in currency speculation. Given the fluctuation of option prices over time, the model describes the distribution of foreign currency as a Weiner process for macroeconomically constrained foreign currencies followed by a Laplace distribution for unconstrained currencies. In a departure from existing currency option models, this model expresses foreign currencies as dependent upon the change in macroeconomic variables, such as inflation, interest rates, and government deficits. The distribution of currency calls is described as a Levy process in the context of an option trader’s risk preferences to account for the multiple discontinuities of a jump process. The paper concludes with three models of price functions of the Weiner process for Euro-related currency options, a Weiner process for stable currency options, and a Levy-Khintchine process for volatile currency calls.
The Valuation of Currency Put Options  [PDF]
Rebecca Abraham
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.811165
Abstract: Investors who seek to profit from depreciating currencies may invest in put options. Upon option exercise, the currency is sold at a high price, and then purchased at the lower future currency value, resulting in a gain for the put buyer. A series of such transactions yields a stream of income for the put investor. Alternatively, the investor could short sell the currency, reaping gains from the difference between the high short sale price and the low future purchase price. This paper derives the theoretical formulations for combined short sale and puts purchase strategies for the US dollar, the Euro, the Australian dollar and the New Zealand dollar, and the Mexican peso. Utility functions are based upon an assumption of declining risk aversio with negative rescale factors and positive threshold factors in a hyperbolic cosine distribution. This distribution intersects with the cosine distribution of short sale prices on the U. S. dollar, the lognormal distribution of short sale prices on the Euro, the Weiner process for shorts on the Australian dollar and the New Zealand dollar, and the Laplace currency distribution for peso shorts. Similar utility functions intersect with Levy-Khintchine jump processes to provide put option prices for each type of foreign currency.
Hedge Fund Investing or Mutual Fund Investing: An Application of Multi-Attribute Utility Theory  [PDF]
Rebecca Abraham
Theoretical Economics Letters (TEL) , 2019, DOI: 10.4236/tel.2019.94042
Abstract: This paper contrasts high-risk, hedge fund trading, with low-risk, mutual fund trading, in terms of their differing utility functions. We envision hedge funds, led by informed traders who use information to seek out investment opportunities, timing market conditions, with the expectation that prices will move in their favor. Directional hedge funds act to influence prices, while non-directional hedge funds do not act to influence prices. We present utility functions based on steeply-sloping Laplace distributions and hyperbolic cosine distributions, to describe the actions of directional hedge fund traders. Less steeply-sloping lognormal distributions, Coulomb wave functions, quadratic utility functions, and Bessel utility functions are used to describe the investing style of non-directional hedge fund traders. Flatter Legendre utility functions and inverse sine utility functions describe the modest profit-making aspirations of mutual fund traders. The paper’s chief contribution is to develop optimal prices quantitatively, by intersecting utility functions with price distributions. Price distributions for directional hedge fund returns are portrayed as sharp increases and decreases, in the form of jumps, in a discrete arrival Poisson-distributed process. Separate equations are developed for directional hedge fund strategies, including event-driven arbitrage, and global macro strategies. Non-directional strategies include commodity trading, risk-neutral arbitrage, and convertible arbitrage, with primarily lognormal pricing distributions, and some Poisson jumps. Mutual funds are perceived to be Markowitz portfolios, lying on the Capital Market Line, or the International Capital Market Line, tangent to the Efficient Frontier of minimum variance-maximum return portfolios.
The candidate genes TAF5L, TCF7, PDCD1, IL6 and ICAM1 cannot be excluded from having effects in type 1 diabetes
Jason D Cooper, Deborah J Smyth, Rebecca Bailey, Felicity Payne, Kate Downes, Lisa M Godfrey, Jennifer Masters, Lauren R Zeitels, Adrian Vella, Neil M Walker, John A Todd
BMC Medical Genetics , 2007, DOI: 10.1186/1471-2350-8-71
Abstract: We genotyped reported polymorphisms of the ten genes, nonsynonymous SNPs (nsSNPs) and, for the IL12B and IL6 regions, tag SNPs in up to 7,888 case, 8,858 control and 3,142 parent-child trio samples. In addition, we analysed data from the Wellcome Trust Case Control Consortium genome-wide association study to determine whether there was any further evidence of an association in each gene region.We found some evidence of associations between type 1 diabetes and TAF5L, PDCD1, TCF7 and IL6 (ORs = 1.05 – 1.13; P = 0.0291 – 4.16 × 10-4). No evidence of an association was obtained for IL12B, IRF5, IL23R, ICAM1, TBX21 and CD40, although there was some evidence of an association (OR = 1.10; P = 0.0257) from the genome-wide association study for the ICAM1 region.We failed to exclude the possibility of some effect in type 1 diabetes for TAF5L, PDCD1, TCF7, IL6 and ICAM1. Additional studies, of these and other candidate genes, employing much larger sample sizes and analysis of additional polymorphisms in each gene and its flanking region will be required to ascertain their contributions to type 1 diabetes susceptibility.Type 1 diabetes is a chronic autoimmune disease with a complex pathogenesis involving multiple genetic and environmental factors. Before the advent of genome-wide association (GWA) studies, disease loci were primarily sought through the testing of candidate genes, selected based usually upon limited prior information about the function of the gene and the pathogenic mechanisms of disease. The candidate gene approach has been successful in finding disease loci, but as only relatively small numbers of genes have been studied, few true positive associations have been found, despite numerous studies and enormous effort [1]. Only five type 1 diabetes loci with compelling evidence had been identified before the advent of GWA studies: the HLA class II genes on chromosome 6p21 [2]; the insulin gene (INS) on 11p15 [3]; CTLA4 on 2q33 [4]; PTPN22 on 1q13 [5,6]; and, IL2RA/
Access, acceptability and utilization of community health workers using diagnostics for case management of fever in Ugandan children: a cross-sectional study
David Mukanga, James K Tibenderana, Stefan Peterson, George W Pariyo, Juliet Kiguli, Peter Waiswa, Rebecca Babirye, Godfrey Ojiambo, Simon Kasasa, Franco Pagnoni, Karin Kallander
Malaria Journal , 2012, DOI: 10.1186/1475-2875-11-121
Abstract: A total of 423 households with under-five children were enrolled into the study in Iganga district, Uganda. Households were selected from seven villages in Namungalwe sub-county using probability proportionate to size sampling. A semi-structured questionnaire was administered to caregivers in selected households. Data were entered into Epidata statistical software, and analysed using SPSS Statistics 17.0, and STATA version 10.Most (86%, 365/423) households resided within a kilometre of a CHW’s home, compared to 26% (111/423) residing within 1 km of a health facility (p?<?0.001). The median walking time by caregivers to a CHW was 10 minutes (IQR 5–20). The first option for care for febrile children in the month preceding the survey was CHWs (40%, 242/601), followed by drug shops (33%, 196/601).Fifty-seven percent (243/423) of caregivers took their febrile children to a CHW at least once in the three month period preceding the survey. Households located 1–3 km from a health facility were 72% (AOR 1.72; 95% CI 1.11–2.68) more likely to utilize CHW services compared to households within 1 km of a health facility. Households located 1–3 km from a CHW were 81% (AOR 0.19; 95% CI 0.10–0.36) less likely to utilize CHW services compared to those households residing within 1 km of a CHW.A majority (79%, 336/423) of respondents thought CHWs services were better with RDTs, and 89% (375/423) approved CHWs’ continued use of RDTs. Eighty-six percent (209/243) of respondents who visited a CHW thought RRTs were useful.ICCM with diagnostics is acceptable, increases access, and is the first choice for caregivers of febrile children. More than half of caregivers of febrile children utilized CHW services over a three-month period. However, one-third of caregivers used drug shops in spite of the presence of CHWs.Malaria and pneumonia are leading causes of morbidity and mortality among under-fives in sub-Saharan Africa [1-3]. Many of these deaths occur at home due to poor access to health
El naturalismo normativo y sus problemas (normativos)
Guillaumin, Godfrey;
Signos filosóficos , 2008,
Abstract: larry laudan's normative naturalism is one of the most important proposals in the philosophy of science. among other issues, it allows appraising different philosophical theories of scientific methodology because it is a descriptive and normative thesis and, at the same time, it avoids naturalistic fallacy. from my point of view, nevertheless, normative naturalism does not satisfactorily explain a couple of roughly common historical situations in science, namely, novel methodological situations and circumstances where successful methodological rules do not work as they used to. in this paper, i confront normative naturalism against these couple of anomalies in order to see its reaction and i conclude that normative naturalism exhibits substantive normative fissures.
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