Age of Sexual Debut and Patterns of Sexual Behaviour in Two Local Government Areas in Southern Nigeria

The study examines the age of sexual debut and patterns of sexual behavior in Ugep, Cross River State, and Badeku and Olunloyo in Oyo State. A survey of households and individuals was conducted in the three communities; qualitative data were also collected through in-depth interviews and focus group discussion. The median age of first sex among never-married males and females were 17 years and 18 years respectively; more than one in five adolescents have had sex before age 16. Nevermarried males and females initiated sex earlier than ever-married, older respondents. That 14 percent of married men keep other sexual partners besides their wives is indicative of substantial extramarital relationship; also 12 percent of never-married male respondents with regular sex partners have other sexual partners. Condom use is fairly high, especially in sexual relations involving non-regular partners. The higher likelihood of alcohol use in sexual liaison with non-regular sex partners is suggestive of high prevalence of transactional sex and spontaneous or unplanned sex under the influence of alcohol, with their implications for the spread of HIV and AIDS. The study underscores the need for adolescent sexual and reproductive health education and behaviour change communication among all segments of the population and inculcation of values less favourable for the spreadof sexually transmitted infection.(Afr J Reprod Health 2012; 16[4]: 81-94)

Modelling and simulation of an industrial RFCCU‑riser reactor for catalytic cracking of vacuum residue

A one-dimensional adiabatic mathematical model was developed for the riser reactor of an industrial residue fluid catalytic cracking unit (RFCCU). A seven-lump kinetic model was presented for the catalytic cracking of vacuum residue, taking cognisance of diffusion resistance, which is a departure from the general norm in the literature. Also, heat transfer resistance between the fluid and solid phases was incorporated into the energy balances for instantaneous and one-dimensional vaporization of feedstock. The developed model was a set of twelve coupled, highly non-linear and stiff ordinary differential equations, ODEs, which was numerically solved with an implicit MATLAB built-in solver, ode23t, designed deliberately for handling stiff differential equations to circumvent the problem of instability associated with explicit methods. An excellent agreement was achieved between the industrial RFCCU plant data and the simulated results of this study, with average absolute deviation being < ± 5% for instantaneous vaporization of feedstock in all cases investigated. Moreover, the simulated results revealed that half of the reactor was relatively redundant as this accounted for only 3% of the conversion. Hence, the findings of this study could be useful to the production practice for the Khartoum Refinery Compan