A Strange Family of Calabi-Yau 3-folds

We study the predictions of mirror symmetry for the 1-parameter family of Calabi-Yau 3-folds $\tilde{X}$ with hodge numbers $h^{11}=31,h^{21}=1$ constructed in \cite{BN}. We calculate the Picard-Fuchs differential equation associated to this family, and use it to predict the instanton numbers on the hypothetical mirror. These exhibit a strange vanishing in odd degrees. We also calculate the monodromy action on H^3(\tilde{X},\QQ) and find that it strangely predicts a positive Euler characteristic for its mirror. From a degenerate fiber of our family we construct a new rigid Calabi-Yau 3-fold. In an appendix we prove the expansion of the conifold period conjectured in \cite{ES} to hold for all 1-parameter families.Comment: 23 page

Pesticide registration, distribution and use practices in Ghana

Ghana has implemented regulation on the registration, distribution and usage of pesticides in order to evaluate their environmental and human health effects. However, environmental monitoring and certified laboratories for pesticide analysis are lacking. Pesticide misuse, misapplication, contamination of the environment and human exposure still continue, and little is known to what extent pesticide registration, distribution and use is properly implemented in Ghana. This study aimed at investigating how the pesticide policy operates in Ghana, how state (policy; national/local) and non-state (importers, dealers’ and farmers) stakeholders function, what their challenges are, and to which extend the policy objectives are achieved. A conceptual framework based on the contextual interaction theory (CIT) was developed, and a review of Ghana’s pesticide policy implementation with two empirical field studies on state policy and non-state policy actors was conducted, supplemented with secondary data, and a number of interviews conducted with stakeholders and informants were used. Results indicate that pesticides are registered in compliance with the law. Non-state actors scored low with respect to their mandate which likely results in environmental and human health risks. Significant association existed between educational level attained and knowledge (χ2 = 3.614; P ≤ 0.05). Work experience or duration of farming also significantly influenced the knowledge of respondents (P 2 = 15.328; P < 0.05). Work experience/duration of farming also significantly influenced attitude at 95% confidence level (P < 0.001), and duration of farming was significantly associated with farm management practices at 5% level of significance (P ≤ 0.05), while state actors are not motivated and resourced. It is recommended to perform preliminary risk assessment to the aquatic environment, to derive threshold levels which are protective of communities, to screen farmers for pesticide exposure and poisoning, to develop well-targeted training programmes for pesticide retailers and farmers on pesticide use, personal protective device use, as well as pesticide management and law. Additionally, pesticide policy implementers have to be motivated and resourced to carry out their mandate, being to execute the pesticide legislation.</p