A Bayesian approach to the multivariate Behrens-Fisher problem under the assumption of proportional covariance matrices

Summary Two independent random samples of sizesN ₁ andN ₂ from multivariate normal populationsN _p (θ₁,∑₁) andN _p (θ₂,∑₂) are considered. Under the null hypothesisH ₀: θ₁=θ₂, a single θ is generated from aN _p(μ, Σ) prior distribution, while underH ₁: θ₁≠θ₂ two means are generated from the exchangeable priorN _p(μ,σ). In both cases Σ will be assumed to have a vague prior distribution. For a simple covariance structure, the Bayes factorB and minimum Bayes factor in favour of the null hypotheses is derived. The Bayes risk for each hypothesis is derived and a strategy is discussed for using the Bayes factor and Bayes risks to test the hypothesis.     

Mutation of either of two cysteine residues or deletion of the amino or carboxy terminus of nonstructural protein NS1 of bluetongue virus abrogates virus-specified tubule formation in insect cells

Virus-specific tubules are characteristic of orbivirus infections and are likely to play an important role in virus morphogenesis. It has been shown that for bluetongue virus (BTV), the prototype orbivirus in the family Reoviridae, the virus-encoded NS1 protein forms tubules in insect cells when the BTV segment M6 gene is expressed by using a baculovirus vector. To understand the function of NS1 tubules and to identify the sequences involved in their polymerization, a series of mutant NS1 genes was generated and expressed in insect cell cultures by using baculovirus vectors. Three of the mutants were deletion mutants. One (AcNS1.dNT10) lacked 10 of the amino-terminal amino acids, and the other two mutants (AcNS1.dCT20 and AcNS1.dCT43) lacked 20 or 43 of the carboxy-terminal amino acids. In addition, site-directed mutants were constructed in which various single cysteines or pairs of cysteines were changed to serines. The ability of each mutant protein to form tubules was investigated. None of the deletion mutants formed tubules. The constructs in which the cysteines at amino acid positions 337 and/or 340 were replaced by serines (e.g., AcNS1.C337S,C340S) also did not form tubules. Instead, the NS1 protein of these and the deletion mutants made ribbon-like structures which formed large aggregates. Mutations involving six other cysteines (i.e., AcNS1.C37S,C43S,AcNS1.C462S,C465S, AcNS1.C104S, and AcNS1.C364S) produced tubules. The results show that both the amino and carboxy termini of the NS1 protein molecule and the cysteines at residues 337 and 340 are essential for tubule formation.     

A microbiological survey of fresh meat in the supermarket trade. Part 2: beef retail cuts

An assessment was made of the microbiological quality of the final product (different retail cuts), produced by two different retail supermarket groups (A & B). The influence of sanitary conditions on the microbiological quality of the final product was evaluated, and the possible influences on shelf life were determined. Supermarket group A (Sup group A) received carcasses with significantly lower surface counts of micro-organisms than supermarket group B (Sup group B), while the latter had a more efficient overall sanitation programme than supermarket group A. Five cuts were monitored for the presence of total aerobic counts, psychrotrophic counts, lactobacilli, Enterobacteriaceae and numbers of Pseudomonadaceae present. A shelf life study was also executed by repeating these enumerations on the same meat samples after refrigerated storage at 5°C for 2 and 4 days, respectively. It is generally accepted that a good refrigeration or chilling regime will preserve the inherent meat quality, but in this study it was found that neither served as a guarantee of quality. The more stringent hygiene at retail level of Sup group B yielded consistently lower mean counts of the different bacterial groups for all the meat cuts monitored and, thus meat with an extended shelf life. The total count (at 30°C) on meat cuts was the highest, followed by the psychrotrophs, the Pseudomonadaceae the Enterobacteriaeae and the lactobacilli. Minced meat generally had the highest mean aerobic total microbial counts. This count on minced meat might be a suitable indicator for monitoring the overall sanitary condition of a retail premises. The results re-emphasized the multi-factorial complexity of fresh meat quality and shelf life. The microbial quality of the raw material (carcasses), the maintenance of the cold chain, sanitary condition of premises, equipment and personnel surfaces and general management practices are factors that collectively determine the microbiological quality of the product.     

The Genetic Heterogeneity among Different Mouse Strains Impacts the Lung Injury Potential of Multiwalled Carbon Nanotubes

Genetic variation constitutes an important variable impacting the susceptibility to inhalable toxic substances and air pollutants, as reflected by epidemiological studies in humans and differences among animal strains. While multiwalled carbon nanotubes (MWCNTs) are capable of causing lung fibrosis in rodents, it is unclear to what extent the genetic variation in different mouse strains influence the outcome. Four inbred mouse strains, including C57Bl/6, Balb/c, NOD/ShiLtJ, and A/J, to test the pro‐fibrogenic effects of a library of MWCNTs in vitro and in vivo are chosen. Ex vivo analysis of IL‐1β production in bone marrow‐derived macrophages (BMDMs) as molecular initiating event (MIE) is performed. The order of cytokine production (Balb/c > A/J > C57Bl/6 > NOD/ShiLtJ) in BMDMs is also duplicated during assessment of IL‐1β production in the bronchoalveolar lavage fluid of the same mouse strains 40 h after oropharyngeal instillation of a representative MWCNT. Animal test after 21 d also confirms a similar hierarchy in TGF‐β1 production and collagen deposition in the lung. Statistical analysis confirms a correlation between IL‐1β production in BMDM and the lung fibrosis. All considered, these data demonstrate that genetic background indeed plays a major role in determining the pro‐fibrogenic response to MWCNTs in the lung.     

Primary beneficiation of tantalite using magnetic separation and acid leaching

Primary beneficiation was successfully performed prior to dissolution of manganotantalite （sample A） and ferrotantalite （sample C） samples obtained from two different mines in the Naquissupa area, Mozambique. Magnetic separation removed the majority of iron and titanium, whereas H2SO4 leaching removed a large portion of thorium and uranium in these samples. Analytical results indicated that 64.14wt% and 72.04wt% of the total Fe and Ti, respectively, and -2wt% each of Nb205 and Ta205 were removed from sample C （ferrotantalite） using the magnetic separation method, whereas only 9.64wt% and 8.66wt% of total Fe203 and TiO2, respectively, and -2wt% each of NbEOs and Ta2O5 were removed from sample A （manganotantalite）. A temperature of 50℃ and a leaching time of 3 h in the presence of concentrated HESOa were observed to be the most appropriate leaching conditions for removal of radioactive elements from the tantalite ores. The results obtained for sample A under these conditions indicated that 64.14wt% U3O8 and 60.77wt% ThO2 were leached into the acidic solution, along with 4.45wt% and 0.99wt% of Nb2O5 and Ta2O5, respectively.     

Re-thinking Spatial Inequalities in South Africa: Lessons from International Experience

Questions relating to the causes and responses to spatial inequalities are attracting renewed international focus. Uncertainty exists in South Africa as to appropriate responses to persistent and deep-rooted spatial inequalities in the country. This article analyses international research into patterns and causes of spatial inequality to inform policy debates on addressing spatial inequality in contemporary South Africa.     

Comment on Fossil-fuel constraints on global warming by A. Zecca and L. Chiari [Energy Policy 38 (2010) 1–3]

Zecca and Chiari (2010) have sought to challenge the findings of Nel and Cooper (2009), who argued that the impending peak and decline of fossil fuel production will most likely lead to a lower emissions trajectory than the majority of scenarios offered by the IPCC. Zecca and Chiari used their own model to produce a higher projection of atmospheric CO₂ concentration, drawing on the conclusions of Archer (2005) to do so.     

Implications of fossil fuel constraints on economic growth and global warming

Energy Security and Global Warming are analysed as 21st century sustainability threats.     

Special Economic Zones in South Africa: Reflections from International Debates

South Africa’s experience with spatial economic interventions has had a chequered history with the Industrial Development Zone programme most recently failing to generate anticipated development. Current policy has shifted to the imminent launch of Special Economic Zones (SEZs) as tools for national (re)industrial development and supporting underdeveloped regions. This paper reflects on recent South African experience with spatial economic interventions and international experience with SEZs paying particular attention to their strengths, weakness and key establishment considerations. It is argued that unfolding South African SEZ planning can be strengthened by learning from the ‘good’ and ‘bad practice’ of international SEZs.     

大都市区的棋盘博弈：区域设计中形态学主题的运用

中国空前的城市化速度与规模亟需更先进的规划设计策略。探索基于形态学的区域设计研究教学方法,从而制定体现中国大都市区特征的空间策略。在设计课程背景下,介绍了以形态学主题为基础的探索性棋盘博弈这一方法论,并应用到粤港澳大湾区空间转型的场景设计中。评估了香港理工大学设计学院和代尔夫特理工大学城市学系连续4年的一系列合作成果。1）沿着设计课程的流程,阐明了教学轨迹。2）调查了不同形态学主题如何影响学生的设计成果,对比了成果的空间特异性以及设计提案的激进程度。3）探讨了是否部分形态学主题更适用于大湾区社会文化与环境的特殊性。在6次课程中,学生们研究了8个形态学主题：点状、线状、条状、巨型街区、放射状、环状、交叉状和边缘状。实践表明存在冗余的主题,因此对主题的进一步确立值得深入研究。需要指出,2所大学的设计课程存在差异,这似乎也影响了棋盘博弈法在各自课程中扮演的作用。整体而言,此教学方法论可以产生远超传统空间规划的设计策略。因此,以形态学主题为基础的棋盘博弈是一套充满前景的方法论,并且今后有望结合更多利益相关方的参与,进行进一步深化和测试。