Induction of triploidy with caffeine treatment in the African catfish (Clarias gariepinus)

Induction of triploidy is one of the biotechnological methods in aquaculture used for genetic manipulation. It refers to a state where organisms have three complete sets of chromosomes instead of two and can result in sterility. Caffeine treatment that is safe and inexpensive, serve to induce triploidy in catfish. To suppress the second meiotic division, fertilized eggs were exposed to three different concentrations (5, 10 and 15 mM) of caffeine solution for 20 min beginning at 3 min after fertilization. After that, the eggs were incubated at ambient temperature until hatching. The induction of triploidy in fry was determined for three concentrations of caffeine by means of flow-cytometric analysis. The lowest rate of triploidy (20.40 ± 1.13%) was obtained in the group treated with 5 mM caffeine and the highest (69.10 ± 2.18%) in the group treated with 15 mM caffeine. Our results suggest that caffeine can be used to induce triploidy in catfish

FIRMS, INCENTIVES, AND THE SUPPLY OF FOOD SAFETY: A FORMAL MODEL OF GOVERNMENT ENFORCEMENT

Recent instances of significant food safety breeches in both meat and biotechnology challenge traditional safety efforts. A formal model utilizing agency theory is used to explore the power relationships between the regulator and the firm. Fundamental issues effecting firms' supply of safety are demonstrated and alternative corrective mechanisms are discussed.Food Consumption/Nutrition/Food Safety,

FOOD SAFETY IN THE MEAT INDUSTRY: A REGULATORY QUAGMIRE

Food Consumption/Nutrition/Food Safety, Livestock Production/Industries,

"You Know You Are Sick, Why Do You Carry A Pregnancy Again?" Applying the Socio-Ecological Model to Understand Barriers to PMTCT Service Utilization in Western Kenya.

ObjectiveThroughout most of sub-Saharan Africa (SSA), prevention of mother-to-child transmission (PMTCT) services are readily available. However, PMTCT programs in SSA have had suboptimal performance compared to other regions of the world. The main objective of this study is to explore the socio-ecological and individual factors influencing the utilization of PMTCT services among HIV-positive pregnant women in western Kenya using a social ecological model as our analytical lens.MethodsData were collected using in-depth interviews with 33 HIV-infected women attending government health facilities in rural western Kenya. Women with HIV-infected infants aged between 6 weeks to 6 months with a definitive diagnosis of HIV in the infant, as well as those with an HIV-negative test result in the infant were interviewed between November 2012 and June 2013. Coding and analysis of the transcripts followed grounded theory tenets. Coding reports were discussed in a series of meetings held among the authors. We then employed constant comparative analysis to discover dominant individual, family, society and structural determinants of PMTCT use.ResultsBarriers to women's utilization of PMTCT services fell within the broad constructs of the socio-ecological model of individual, family, society and structural determinants. Several themes cut across the different steps of PMTCT cascade and relate to different constructs of the socio-ecological model. These themes include: self-motivation, confidence and resilience, family support, absence or reduced stigma, right provider attitude and quality of health services provided. We also found out that these factors ensured enhanced maternal health and HIV negative children.ConclusionThe findings of this study suggest that a woman's social environment is an important determinant of MTCT. PMTCT Interventions must comprehensively address multiple factors across the different ecological levels. More research is however required for the development of multi-component interventions that combine strategies at different ecological levels

Implementation of repeat HIV testing during pregnancy in Kenya: a qualitative study.

BackgroundRepeat HIV testing in late pregnancy has the potential to decrease rates of mother-to-child transmission of HIV by identifying mothers who seroconvert after having tested negative for HIV in early pregnancy. Despite being national policy in Kenya, the available data suggest that implementation rates are low.MethodsWe conducted 20 in-depth semi-structured interviews with healthcare providers and managers to explore barriers and enablers to implementation of repeat HIV testing guidelines for pregnant women. Participants were from the Nyanza region of Kenya and were purposively selected to provide variation in socio-demographics and job characteristics. Interview transcripts were coded and analyzed in Dedoose software using a thematic analysis approach. Four themes were identified a priori using Ferlie and Shortell's Framework for Change and additional themes were allowed to emerge from the data.ResultsParticipants identified barriers and enablers at the client, provider, facility, and health system levels. Key barriers at the client level from the perspective of providers included late initial presentation to antenatal care and low proportions of women completing the recommended four antenatal visits. Barriers to offering repeat HIV testing for providers included heavy workloads, time limitations, and failing to remember to check for retest eligibility. At the facility level, inconsistent volume of clients and lack of space required for confidential HIV retesting were cited as barriers. Finally, at the health system level, there were challenges relating to the HIV test kit supply chain and the design of nationally standardized antenatal patient registers. Enablers to improving the implementation of repeat HIV testing included client dissemination of the benefits of antenatal care through word-of-mouth, provider cooperation and task shifting, and it was suggested that use of an electronic health record system could provide automatic reminders for retest eligibility.ConclusionsThis study highlights some important barriers to improving HIV retesting rates among pregnant women who attend antenatal clinics in the Nyanza region of Kenya at the client, provider, facility, and health system levels. To successfully implement Kenya's national repeat HIV testing guidelines during pregnancy, it is essential that these barriers be addressed and enablers capitalized on through a multi-faceted intervention program

Effects of the loading direction on high strain rate behavior of woven graphite/epoxy composites

Effects of the loading direction on high strain rate behavior of cylindrical woven graphite/epoxy composites are presented. Compressive split Hopkinson pressure bar (SHPB) was used for high strain rate experiments. Cylindrical specimens were loaded diametrically and transversely at the impact energies of 67 J, 163 J, and 263 J. Micro Laser Raman spectroscopy and scanning electron microscopy (SEM) were used for surface characterization. It is observed that diametrically loaded specimens show permanent plastic deformation with high ductility resulting in a catastrophic failure while transversely loaded specimens exhibit viscoplastic deformation with some recoverable damage. As a result of this, Raman peak shifted to higher values for the diametrically loaded fibers whereas almost no change was observed in the Raman shift of transversely loaded fibers

Multi-domain active sound control and noise shielding

This paper describes an active sound control methodology based on difference potentials. The main feature of this methodology is its ability to automatically preserve “wanted” sound within a domain while canceling “unwanted” noise from outside the domain. This method of preservation of the wanted sounds by active shielding control is demonstrated with various broadband and realistic sound sources such as human voice and music in multiple domains in a one-dimensional enclosure. Unlike many other conventional active control methods, the proposed approach does not require the explicit characterization of the wanted sound to be preserved. The controls are designed based on the measurements of the total field on the boundaries of the shielded domain only, which is allowed to be multiply connected. The method is tested in a variety of experimental cases. The typical attenuation of the unwanted noise is found to be about 20 dB over a large area of the shielded domain and the original wanted sound field is preserved with errors of around 1 dB and below through a broad frequency range up to 1 kHz. © 2011 Acoustical Society of Americ

Rare Decay of the Top t -> cgg in the Standard Model

We calculate the one-loop flavor changing neutral current top quark decay t -> cgg in the Standard Model. We demonstrate that the rate for t -> cgg exceeds the rate for a single gluon emission t -> cg by about two orders of magnitude, while the rate for t -> cq barq (q=u) is slightly smaller than for t -> cg.Comment: 22 pages, 4 figures and 2 tables. Typo in Eq.2.1 corrected, text slightly modified, references added. Version to appear in Phys.Rev.

The Casimir Force in Randall Sundrum Models

We discuss and compare the effects of one extra dimension in the Randall Sundrum models on the evaluation of the Casimir force between two parallel plates. We impose the condition that the result reproduce the experimental measurements within the known uncertainties in the force and the plate separation, and get an upper bound kR < 20 if the curvature parameter k of AdS_5 is equal to the Planck scale. Although the upper bound decreases as k decreases, kR ~ 12, which is the required value for solving the hierarchy problem, is consistent with the Casimir force measurements. For the case where the 5th dimension is infinite, the correction to the Casimir force is very small and negligible.Comment: 16 pages, 2 figures, references added, text improved, accepted for publication in PR

Effect of the contact geometry on high strain rate behavior of woven graphite/epoxy composites

Effects of the loading direction on high strain rate behavior of cylindrical woven graphite/epoxy composites are presented. Compressive split Hopkinson pressure bar (SHPB) was used for high strain rate experiments. Cylindrical specimens were loaded diametrically and transversely at the impact energies of 67 J, 163 J, and 263 J. Micro Laser Raman spectroscopy and scanning electron microscopy (SEM) were used for surface characterization. It is observed that diametrically loaded specimens show permanent plastic deformation with high ductility resulting in a catastrophic failure while transversely loaded specimens exhibit viscoplastic deformation with some recoverable damage. As a result of this, Raman peak shifted to higher values for the diametrically loaded fibers whereas almost no change was observed in the Raman shift of transversely loaded fibers