Phosphate feeding to permit growth while maintaining secondary product synthesis

Maintaining high metabolic activities for extended periods by feeding small amounts of the growth limiting nutrient was examined for the production of cycloheximide by Streptomyces griseus . Batch studies indicated that increased initial phosphate levels led to increased cell concentrations, stimulated glucose utilization, and over a limited range (<0.6 g/l KH 2 PO 4 ) did not adversely affect cycloheximide production rates. Semi-continuous phosphate feeding was observed to permit limited cell growth, and to enhance metabolic activities (i. e. glucose utilization). The effect of semi-continuous phosphate feeding on antibiotic production depended on the feed rate, with high feed rates suppressing production.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46756/1/253_2004_Article_BF00451634.pd

Identifying structures, processes, resources and needs of research ethics committees in Egypt

<p>Abstract</p> <p>Background</p> <p>Concerns have been expressed regarding the adequacy of ethics review systems in developing countries. Limited data are available regarding the structural and functional status of Research Ethics Committees (RECs) in the Middle East. The purpose of this study was to survey the existing RECs in Egypt to better understand their functioning status, perceived resource needs, and challenges.</p> <p>Methods</p> <p>We distributed a self-administered survey tool to Egyptian RECs to collect information on the following domains: general characteristics of the REC, membership composition, ethics training, workload, process of ethics review, perceived challenges to effective functioning, and financial and material resources. We used basic descriptive statistics to evaluate the quantitative data.</p> <p>Results</p> <p>We obtained responses from 67% (12/18) of the identified RECs. Most RECs (10/12) have standard operating procedures and many (7/12) have established policies to manage conflicts of interests. The average membership was 10.3 with a range from 7-19. The predominant member type was physicians (69.5% of all of the REC members) with little lay representation (13.7%). Most RECs met at least once/month and the average number of protocols reviewed per meeting was 3.8 with a range from 1-10. Almost three-quarters of the members from all of the 12 RECs indicated they received some formal training in ethics. Regarding resources, roughly half of the RECs have dedicated capital equipment (e.g., meeting room, computers, office furniture, etc); none of the RECs have a formal operating budget. Perceived challenges included the absence of national research ethics guidelines and national standards for RECs and lack of ongoing training of its members in research ethics.</p> <p>Conclusion</p> <p>Our study documents several areas of strengths and areas for improvements in the operations of Egyptian RECs. Regarding strengths, many of the existing RECs meet frequently, have a majority of members with prior training in research ethics, and have written policies. Regarding areas for improvements, many RECs should strive for a more diverse membership and should receive more financial resources and administrative support personnel. We recommend that RECs include more individuals from the community and develop a continuing educational program for its members. Institutional officials should be aware of the resource capacity needs of their RECs.</p

Combination of the W boson polarization measurements in top quark decays using ATLAS and CMS data at \sqrt{s} = 8 TeV

The combination of measurements of the W boson polarization in top quark decays performed by the ATLAS and CMS collaborations is presented. The measurements are based on proton-proton collision data produced at the LHC at a centre-of-mass energy of 8 TeV, and corresponding to an integrated luminosity of about 20 fb^{-1} for each experiment. The measurements used events containing one lepton and having different jet multiplicities in the final state. The results are quoted as fractions of W bosons with longitudinal (F_{0}), left-handed (F_{L}), or right-handed (F_{R}) polarizations. The resulting combined measurements of the polarization fractions are F0 = 0.693 ± 0.014 and FL = 0.315 ± 0.011. The fraction F_{R} is calculated from the unitarity constraint to be F_{R} = −0.008 ± 0.007. These results are in agreement with the standard model predictions at next-to-next-to-leading order in perturbative quantum chromodynamics and represent an improvement in precision of 25 (29)% for F_{o} (F_{L}) with respect to the most precise single measurement. A limit on anomalous right-handed vector (VR), and left- and right-handed tensor (g_{L}, g_{R})tWb couplings is set while fixing all others to their standard model values. The allowed regions are [−0.11, 0.16] for V_{R}, [−0.08, 0.05] for g_{L}, and [−0.04, 0.02] for g_{R}, at 95% confidence level. Limits on the corresponding Wilson coefficients are also derived