Aquaculture in Zambia: An overview and evaluation of the sector’s responsiveness to the needs of the poor

Given the recent expansion and commercialization of aquaculture in Zambia, an important question that needs to be explored is how have the recent changes in the Zambian aquaculture sector contributed to the needs of the poor? The aim of this report is to (a) outline the current trajectory of aquaculture development in Zambia and (b) evaluate whether these development efforts are inclusive of and responsive to the needs of the poor

The small FNR regulon of Neisseria gonorrhoeae: comparison with the larger Escherichia coli FNR regulon and interaction with the NarQ-NarP regulon

BACKGROUND: Neisseria gonorrhoeae can survive during oxygen starvation by reducing nitrite to nitrous oxide catalysed by the nitrite and nitric oxide reductases, AniA and NorB. The oxygen-sensing transcription factor, FNR, is essential for transcription activation at the aniA promoter, and full activation also requires the two-component regulatory system, NarQ-NarP, and the presence of nitrite. The only other gene known to be activated by the gonococcal FNR is ccp encoding a cytochrome c peroxidase, and no FNR-repressed genes have been reported in the gonococcus. In contrast, FNR acts as both an activator and repressor involved in the control of more than 100 operons in E. coli regulating major changes in the adaptation from aerobic to anaerobic conditions. In this study we have performed a microarray-led investigation of the FNR-mediated responses in N. gonorrhoeae to determine the physiological similarities and differences in the role of FNR in cellular regulation in this species. RESULTS: Microarray experiments show that N. gonorrhoeae FNR controls a much smaller regulon than its E. coli counterpart; it activates transcription of aniA and thirteen other genes, and represses transcription of six genes that include dnrN and norB. Having previously shown that a single amino acid substitution is sufficient to enable the gonococcal FNR to complement an E. coli fnr mutation, we investigated whether the gonococcal NarQ-NarP can substitute for E. coli NarX-NarL or NarQ-NarP. A plasmid expressing gonococcal narQ-narP was unable to complement E. coli narQP or narXL mutants, and was insensitive to nitrate or nitrite. Mutations that progressively changed the periplasmic nitrate sensing region, the P box, of E. coli NarQ to the sequence of the corresponding region of gonococcal NarQ resulted in loss of transcription activation in response to the availability of either nitrate or nitrite. However, the previously reported ligand-insensitive ability of gonococcal NarQ, the "locked on" phenotype, to activate either E. coli NarL or NarP was confirmed. CONCLUSION: Despite the sequence similarities between transcription activators of E. coli and N. gonorrhoeae, these results emphasise the fundamental differences in transcription regulation between these two types of pathogenic bacteria

FABRICATION OF URANIUM OXIDE FUEL ELEMENTS

The fabrication of UO/sub 2/ fuel elements clad in metallic sheaths by swaging, rolling, and coextrusion was investigated. The effects of the type of UO/sub 2/ and of the materials and dimensions of the sheath were investigated. Fused UO/sub 2/ swaged in stairless-steel tubing reached a maximum density of 93% of theoretical. (auth

Cross-National Logo Evaluation Analysis: An Individual Level Approach

The universality of design perception and response is tested using data collected from ten countries: Argentina, Australia, China, Germany, Great Britain, India, the Netherlands, Russia, Singapore, and the United States. A Bayesian, finite-mixture, structural-equation model is developed that identifies latent logo clusters while accounting for heterogeneity in evaluations. The concomitant variable approach allows cluster probabilities to be country specific. Rather than a priori defined clusters, our procedure provides a posteriori cross-national logo clusters based on consumer response similarity. To compare the a posteriori cross-national logo clusters, our approach is integrated with Steenkamp and Baumgartner’s (1998) measurement invariance methodology. Our model reduces the ten countries to three cross-national clusters that respond differently to logo design dimensions: the West, Asia, and Russia. The dimensions underlying design are found to be similar across countries, suggesting that elaborateness, naturalness, and harmony are universal design dimensions. Responses (affect, shared meaning, subjective familiarity, and true and false recognition) to logo design dimensions (elaborateness, naturalness, and harmony) and elements (repetition, proportion, and parallelism) are also relatively consistent, although we find minor differences across clusters. Our results suggest that managers can implement a global logo strategy, but they also can optimize logos for specific countries if desired.adaptation;standardization;Bayesian;international marketing;design;Gibbs sampling;concomitant variable;logos;mixture models;structural equation models

Quantum Statistical Model of Nuclear Multifragmentation in the Canonical Ensemble Method

A quantum statistical model of nuclear multifragmentation is proposed. The recurrence equation method used within the canonical ensemble makes the model solvable and transparent to physical assumptions and allows to get results without involving the Monte Carlo technique. The model exhibits the first order phase transition. Quantum statistics effects are clearly seen on the microscopic level of occupation numbers but are almost washed out for global thermodynamic variables and the averaged observables studied. In the latter case, the recurrence relations for multiplicity distributions of both intermediate-mass and all fragments are derived and the specific changes in the shape of multiplicity distributions in the narrow region of the transition temperature is stressed. The temperature domain favorable to search for the HBT effect is noted.Comment: 38 pages, 11 figure

Demographic Trends in US HIV Diagnoses, 2008–2017: Data Movies

In this editorial, we introduce the data movie as a tool for investigating and communicating changing patterns of disease using the example of HIV in the United States. The Centers for Disease Control and Prevention currently tracks all new HIV diagnoses through the National HIV Surveillance System. Understanding what these data tell us is critical to the goal of ending the HIV epidemic in the United States.1 However, summarizing trends across multiple population characteristics simultaneously—for example, exploring how the age distribution of new diagnoses varies by geographic region and how that relationship has changed over time—can be difficult. Because data movies allow us to visualize complex relationships more easily than large tables or paneled figures, they can help us take full advantage of our increasingly rich national surveillance data

Credibly Identifying Social Effects: Accounting for Network Formation and Measurement Error

Understanding whether and how connections between agents (networks) such as declared friendships in classrooms, transactions between firms, and extended family connections, influence their socio-economic outcomes has been a growing area of research within economics. Early methods developed to identify these social effects assumed that networks had formed exogenously, and were perfectly observed, both of which are unlikely to hold in practice. A more recent literature, both within economics and in other disciplines, develops methods that relax these assumptions. This paper reviews that literature. It starts by providing a general econometric framework for linear models of social effects, and illustrates how network endogeneity and missing data on the network complicate identification of social effects. Thereafter, it discusses methods for overcoming the problems caused by endogenous formation of networks. Finally, it outlines the stark consequences of missing data on measures of the network, and regression parameters, before describing potential solutions

Antiretroviral therapy and the prevalence and incidence of diabetes [2] (multiple letters)

In the study by Brown et al,1 the authors did not mention several limitations that might have an important impact on the interpretation of the results. First, the study only included men, who were mostly white (approximately 86%). Therefore, the results cannot be extrapolated to women and other ethnic groups. Second, the family history of diabetes was not ascertained in the study participants, and this could have confounded the magnitude of differences in prevalence and incidence of diabetes between the 2 study groups. Third, the reported prevalence and incidence rates of diabetes were likely to be overestimated because the diagnosis of diabetes was not confirmed by a repeated measurement of fasting plasma glucose

Cross-National Logo Evaluation Analysis: An Individual Level Approach

The universality of design perception and response is tested using data collected from ten countries: Argentina, Australia, China, Germany, Great Britain, India, the Netherlands, Russia, Singapore, and the United States. A Bayesian, finite-mixture, structural-equation model is developed that identifies latent logo clusters while accounting for heterogeneity in evaluations. The concomitant v