Integrating landscapes that have experienced rural depopulation and ecological homogenization into tropical conservation planning

If current trends of declining fertility rates and increasing abandonment of rural land as a result of urbanization continue, this will signal a globally significant transformation with important consequences for policy makers interested in conservation planning. This transformation is presently evident in a number of countries and projections suggest it may occur in the future in many developing countries. We use rates of population growth and urbanization to project population trends in rural areas for 25 example countries. Our projections indicate a general decline in population density that has either occurred already (e.g., Mexico) or may occur in the future if current trends continue (e.g., Uganda). Using both temperate and tropical examples we present evidence that this process will lead to ecological homogenization as a dominant habitat (e.g., forest replaces a mosaic of human-maintained landscapes), resulting in declines in biodiversity at the local scale. Building on this information, we consider research programs that need to be conducted so that policy makers are prepared to effectively manage depopulated rural areas

A Computational Model for Temperature Monitoring During Human Liver Treatment by Nd:YaG Laser Interstitial Thermal Therapy (LITT)

Describing heat transfer in biological organs is absolutely challenging because it is involved with many complex phenomena. Therefore, understanding the optical and thermal properties of living system during external irradiation sources such as laser interstitial thermal therapy (LITT) are too important for therapeutic purposes, especially for hyperthermia treatments. The purpose of this study was to determine a proper laser power and irradiation time for LITT applicator to irradiate liver tissue during hyperthermia treatment. For this aim, bioheat equation in one-dimensional spherical coordinate is solved by Green function method to simulate temperature distribution and rate of damage around irradiated target and how thermal and optical properties such as laser power, laser exposure time, and blood perfusion rate affect the rate of temperature distribution. Guiding equations according to the suggested boundary conditions are written and solved by MATLAB software. The outcomes show that increasing laser exposure time and power increase the temperature, especially at the nearest distance from the center of diffusion. Accordingly, a decrease in blood perfusion rate leads to decrease temperature distribution. The findings show that the model is useful to help the physicians to monitor the amount of heat diffusion by laser power during the treatment to protect healthy cells

Assessment of indoor radon-222 concentrations in the vicinity of Manyoni uranium deposit, Singida

This study aimed to assess indoor radon concentrations in the vicinity of the Manyoni Uranium Deposit in Singida. The concentrations were measured for two months in 32 houses in the vicinity of Manyoni Uranium Deposit and 9 houses at Manyoni town using a portable radon gas monitor (Alpha –GUARDTM). The radon concentrations ranged from 27±3 to 518±28 Bq/m3with the overall mean of 166±12 Bq/m3 which is above recommended values of 100 Bq/m3 and 148 Bq/m3 set by WHO (World Health Organization) and EPA (Environmental Protection Agency's), respectively. The overall mean of indoor radon concentrations from each village were Kipondoda (169±13 Bq/m3), Muhalala (177±16 Bq/m3), Mwanzi, (287±13 Bq/m3), Mitoo (325±21 Bq/m3) and Majengo (377±23 Bq/m3) which exceed the limit set by WHO (World Health Organization) and EPA (Environmental Protection Agency). The value of 325±21 Bq/m3 and 377±23 Bq/m3 from Mitoo and Majengo respectively, exceed the limit of 300 Bq/m3 recommended by ICRP (International Commission on Radiation Protection). Thus there is a non-negligible probability of incurring stochastic effects for people living in the vicinity of Manyoni Uranium mine. It is recommended that human activities should be controlled   near the uranium deposits and dwelings should be well ventilated.Keywords: Indoor radon, Concentrations, Cancer, Manyoni uranium deposit, Alpha –GUAR

Determination of radon gas and respirable ore dust concentrations in the underground merelani Tanzanite mines

This study has estimated the concentrations of radon gas and respirable ore dust in the Merelani underground tanzanite mines. Two different portable monitors were used to measure the radon gas and respirable ore dust concentrations respectively. The mean radon gas concentration (disintegrations per second per cubic meter) ranges from 40.1 Bq/m3 to 4.2x103 Bq/m3 with the geometric mean of 118.4 Bq/m3 which is below the ICRP workplace guidance level of 500 - 1500 Bq/m3. The estimated mean annual effective dose (D) was 1.6 mSv which is significantly lower than the external exposure annual effective dose of 20 mSv and the annual organ dose limit of 2.4 mSv. The overall concentrations of respirable ore dust arithmetic mean was 18.2 g/m3 and the geometric mean of 2.1 g/m3 which is very high compared to the guidance level of 2 g/m3. The respirable dust was mainly produced during drilling and blasting of rocks, under normal conditions the geometric mean of respirable gas concentrations was 0.8 g/m3. It is recommended that immediate intervention such as providing proper ventilation during the two processes to dilute radon levels in underground mines and the monitoring should be done regularly

Texture of Two Vanishing Subtraces in Neutrino Mass Matrix and Current Experimental Tests

We present a full phenomenological and analytical study for the neutrino mass matrix characterized by two vanishing $2\times2$ subtraces. We update one past result in light of the recent experimental data. Out of the fifteen possible textures, we find seven cases can accommodate the experimental data instead of eight ones in the past study. We also introduce few symmetry realizations for viable and nonviable textures based on non-abelian ($A_4$ or $S_4$) flavor symmetry within type II seesaw scenario.Comment: pdflatex, 57 pages, 10 tables, 9 figures, version to appear in PR

Potential for biological control of rice yellow mottle virus vectors

Insect pests and disease infestations are the primary constraints in rice (Oryza sativa) production systems in Africa and Asia. For Cameroon in particular, the rice yellow mottle virus (RYMV) is increasingly a serious problem to rice production. During the poulations of the various insect vectors of RMYV are not known, andhence the need for this study. Unfortunately, 2002 - 2004, two sampling methods were combined to assess the population of insects vectors of rice yellow mottle virus (RYMV) in the three major irrigated rice ecosystems in northern Cameroon (Lagdo, Maga and Yagoua), and in low land rice fields. Sampling was conducted using sweepnet and D-Vac (sucking trap) fortnightly in 2002 and 2003 until mid October in low land rice fields, while in the irrigated fields, samplings occurred between December and April. Rearing using dead insects was conducted simultaneously in the laboratory to identify the parasitoid insect species. From samples obtained at differentsites: (i) the dominant structure of the RYMV insect vectors was analysed according to the rice phenology; and (ii) the diversity and the occurrence of potential major groups of predators and parasitoids were assessed. Among the RYMV insect vectors sampled: Chaetocnema pulla Chapuis (Coleoptera: Chrysomelidae), Chnootriba similisMulsant (Coleoptera: Coccinellidae), Trichispa sericea Guerin-Meneville (Coleoptera: Chrysomelidae), Locris rubra Fabricius (Hemiptera: Cicadellidae), Oxya hyla Stål (Orthoptera: Acrididae), and Conocephalus longipennis (de Haan) (Orthoptera: Tettigoniidae) were the most encountered insect species during the rice growing seasons.With regard to predator populations, spiders (Araneae) were the most abundant, with high concurrency of Pardosa spp (> 42 %) in all sites. In Maga and Yagoua sites, the carabid beetle species, Abacetus crenulatus Dejean and Abacetus foveolatus Chaudoir, were the most numerous whereas the Lagdo site was highly colonisedby Clivina. erythropyga Putzeys. Paederus sabaeus Erichson, and Stenus ravus Puthz were the most abundant Staphylinid beetles. From reared dead RYMV insect vectors, Eurytoma spp., Pediobius spp., Tetrastichus spp. and Telenomus spp. emerged as parasitoids. Results of this study reveal a great potential of biological controlagainst rice yellow mottle virus vectors using predators and parastoids. This potential should be developed to manage the yield losses caused by the virus infection in rice cropping systems