Global atmospheric and oceanic perturbations and local weather variability induced factors highly alter the rainfall pattern of a region. Such factors result in extreme events of devastating nature to mankind. Rainfall Intensity Duration Frequency (IDF) is one of the most commonly used tools in water resources engineering particularly to identify design storm event of various magnitude, duration and return period simultaneously. In light of this, the present study is aimed at developing rainfall IDF relationship for entire Rwanda based on selected twenty six (26) rainfall gauging stations. The gauging stations have been selected based on reliable rainfall records representing the different geographical locations varying from 14 to 83 years of record length. Daily annual maximum rainfall data has been disaggregated into sub-daily values such as 0.5 hr, 1 hr, 3 hr, 6 hr and 12 hr and fitted to the probability distributions. Quantile estimation has been made for different return periods and best fit distribution is identified based on least square standard error of estimate. At-site and regional IDF parameters were computed and subsequent curves were established for different return period. The moment ratio diagram (MRD) and L-moment ratio diagram (LMRD) methods have been used to fit frequency distributions and identify homogeneous regions for observed 24-hr maximum annual rainfall. The rainfall stations have been divided into five homogeneous rainfall regions for all 26 stations. The results of present analysis can be used as useful information for future water resources development planning purposes.

In vitro ovicidal and larvicidal activities of extracts of the seeds of Embelia rowlandii were investigated on unembryonated and embryonated eggs, first and second stage larvae of Heligmosomoides bakeri. Three different extracts were prepared with distilled water (DW) and 95% ethanol. The organic extract was first diluted with 3% Tween and then distilled water added to obtain five different concentrations (625, 1250, 2500, 3750 and 5000 µg/ml). These concentrations were put in contact with eggs and larvae of H. bakeri. One milliliter of each extract at different concentrations and controls were added to 1 ml solution containing 30 to 40 eggs or 10 to 15 larvae (L 1 and L 2 larvae) and distributed in different Petri dishes. Both eggs and larvae were incubated at 24°C and exposure time was 48 h for fresh (unembryonated) eggs, 6 h for embryonated eggs, 24 h for L 1 and L 2 larvae, respectively. Distilled water and 3% Tween were used as negative controls in the bioassay. These placebos neither affected egg development, hatching nor larval survival. A significant effect was obtained with cold water extract (CWE), hot water extract (HWE) and ethanolic extract (EtE) and differences were observed depending on the parasitic stage. CWE, HWE and EtE inhibited embryonic development (60.5, 82.5 and 46.9%) and hatching (85.8, 74.1 and 41.0%), respectively at 5000 µg/ml. All the three extracts killed both L 1 larvae (84.5, 86.0 and 61.2%) and L 2 larvae (65.2, 83.7 and 33.3%) respectively at 5000 µg/ml. These in vitro results suggest that extracts of E. rowlandii possess ovicidal and larvicidal properties.

Recibido 01 de febrero de 2012 • Corregido 22 de octubre de 2012 • Aceptado 07 de noviembre de 2012Resumen. Este artículo presenta distintas perspectivas teóricas y sus aproximaciones epistemológicas en el estudio de la discapacidad. Explica distintos enfoques para concebir la discapacidad según los diferentes aspectos que cada uno enfatiza, así como algunos de los debates entre dichos enfoques. El artículo aporta a la clarificación teórico-conceptual para el estudio e investigación sobre la discapacidad.Palabras claves. Perspectivas teóricas, enfoques, aproximaciones epistemológicas, modelos, discapacidad.Abstract. This paper provides theoretical perspectives and the corresponding epistemological approaches on the study of disabilities. It explains diverse focuses to see disabilities from their different points of view; it also includes debates between those focuses. This paper contributes to a conceptual-theoretical clarification for the study and research on disabilities. Rica donde ha formado parte del Proyecto UNA educación de calidad que atiende a estudiantes con discapacidad en dicha institución. Tiene publicaciones en los campos de Pedagogía y de Educación Especial.

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