The dynamics of measles in sub-Saharan Africa

Although vaccination has almost eliminated measles in parts of the world, the disease remains a major killer in some high birth rate countries of the Sahel. On the basis of measles dynamics for industrialized countries, high birth rate regions should experience regular annual epidemics. Here, however, we show that measles epidemics in Niger are highly episodic, particularly in the capital Niamey. Models demonstrate that this variability arises from powerful seasonality in transmission-generating high amplitude epidemics-within the chaotic domain of deterministic dynamics. In practice, this leads to frequent stochastic fadeouts, interspersed with irregular, large epidemics. A metapopulation model illustrates how increased vaccine coverage, but still below the local elimination threshold, could lead to increasingly variable major outbreaks in highly seasonally forced contexts. Such erratic dynamics emphasize the importance both of control strategies that address build-up of susceptible individuals and efforts to mitigate the impact of large outbreaks when they occur.     

A Soft Systems Methodology Approach to Occupational Cancer Control Problem: a Case Study of the Ministry of Petroleum of Iran

Petroleum industries of Iran offer some of the best job opportunities within Iranian labor market. However, due to the attributes of the chemicals used in these industries, their staffs are exposed to various risk factors of several chronic diseases. Such exposures might lead to cancer incidence after a decade or two. The Ministry of Petroleum (MoP) runs an organization, namely Petroleum Industry Health Organization (PIHO), which is responsible for the health insurance of the personnel working in Petroleum industries. PIHO and Health, Safety & Environment (HSE) units play fundamental roles in providing the employees with health services during their professional life and retirement period. Yet, these organizations still do not have a system to specify occupational cancer control mechanisms at the MoP. The negative influences of cancer on patients suffering from it as well as its heavy costs of treatment have forced MoP to put measures of coping with this chronic disease in the first priority. This paper aims to define the structure and design a framework for MoP’s occupational cancer control problem as the first step for improving the described situation. Given the presence of various stakeholders and actors, and the wide range of complexities of this problematic situation, we have adopted Soft System Methodology (SSM). We have reached an agreement with the problem owners on a rich picture, CATWOE analysis, root definition and a conceptual model for the way this situation could improve within real world circumstances. The results were obtained through various sessions with practitioner from different departments of MoP, while the conflict of interests was common.     

Synthesis and characterization of carbon-coated cobalt ferrite nanoparticles

Cobalt ferrite nanoparticles (CFNPs) were prepared via a reverse micelle method. The CFNPs were subsequently coated with carbon shells by means of thermal chemical vapor deposition (TCVD). In this process, acetylene gas (C₂H₂) was used as a carbon source and the coating was carried out for 1, 2, or 3 h at 750°C. The Ar/C₂H₂ ratio was 10:1. Heating during the TCVD process resulted in a NP core size that approached 30 nm; the thickness of the shell was less than 10 nm. The composition, structure, and morphology of the fabricated composites were characterized using X-ray diffraction, simultaneous thermal analysis, transmission electron microscopy, high-resolution transmission electron microscopy, and selected-area diffraction. A vibrating sample magnetometer was used to survey the samples’ magnetic properties. The deposited carbon shell substantially affected the growth and magnetic properties of the CFNPs. Micro-Raman spectroscopy was used to study the carbon coating and revealed that the deposited carbon comprised graphite, multiwalled carbon nanotubes, and diamond- like carbon. With an increase in coating time, the intensity ratio between the amorphous and ordered peaks in the Raman spectra decreased, which indicated an increase in crystallite size.     

Zoeal stages of Hiplyra variegata (Rüppell, 1830) (Crustacea: Brachyura: Leucosiidae) reared in the laboratory and collected from plankton at Al-Kharrar creek,central Red Sea

The zoeal stages of Hiplyra variegata are described and illustrated for the first time. Zoea I was obtained from an ovigerous female, and the zoea II and zoea III stages were captured in the plankton (their identity was confirmed by rearing some of them from earlier stages). Comparisons are made with the only other species of the genus of which larvae are known, i.e. H. platycheir. The presence of a lateral spine on the carapace of zoea I is one of the most important characters that can be used for easy recognition of H. variegata. It is important to note that the third zoea of H. variegata has four small spines at each posterolateral margin of the carapace, in contrast to three spines in other species.     

Genetic diversity of rhizobial populations recovered from three Lotus species cultivated in the infra-arid Tunisian soils

gments from each strain based on the UPGMA algorithm from the combined patterns showed that Lotus isolates are very diverse and that they were affiliated to Sinorhizobium,Rhizobium,and Mesorhizobium genera.     

Structural Decomposition Analysis to Investigate the Changes in Energy Consumption in Pakistan

The world energy demand is increasing due to rapid growth in the global economy, industrialization, and urbanization. Pakistan is also confronted with increasing energy demand on one hand and is confronted with the challenge of energy demand-supply gap on the other hand. Since energy is the major driver for growth, it becomes important to investigate the trends of energy consumption in a country and the factors that are most affecting the changes in the use of energy. This particular study aims to investigate the use of energy by all the economic sectors of Pakistan during 2000–2012.The major contribution is the first time application of structural decomposition analysis(SDA) for energy usage along with using Input-Output data for the period of 2002–2012. The results show the fluctuation of the energy intensity of the sectors throughout the study period. Also, the overall effect of energy intensity is negative on energy consumption and it shows a negative contribution value of-80.90% for the study period. Furthermore, the focus on more energy-intensive products like cement,automobiles, iron, steel products and the increasing final demand of the economy contributes to the growth of energy consumption in Pakistan during 2000–2012.     

Simulation-based automatic generation of risk scenarios

A methodology for automatically generating risk scenarios is presented.Its main idea is to let the system model "express itself" through simulation.This is achieved by having the simulation model driven by an elaborated simulation engine,which:(i) manipulates the generation of branch points,i.e.event occurrence times;(ii) employs a depth-first systematic exploration strategy to cover all possible branch paths at each branch point.In addition,a backtracking technique,as an extension,is implemented to recover some missed risk scenarios.A widely discussed dynamic reliability example(a holdup tank) is used to aid in the explanation of and to demonstrate the effectiveness of the proposed methodology.     

r-排列非递归生成算法及应用

提出一种利用回溯法生成r-排列的算法.该算法使用栈和队列,并引入标记已选元素的方法,避免了回溯时的重复选择.生成的r-排列具有分组和对称性,且符合字典序.此算法也能生成全排列.利用该算法提出了r-组合生成算法,分析了它们的时间和空间复杂度,并介绍了r-排列和r-组合算法在任务安排问题中的应用.     

Mutations in the gene encoding the 3'-5' DNA exonuclease TREX1 cause Aicardi-Goutières syndrome at the AGS1 locus

Aicardi-Goutières syndrome (AGS) presents as a severe neurological brain disease and is a genetic mimic of the sequelae of transplacentally acquired viral infection. Evidence exists for a perturbation of innate immunity as a primary pathogenic event in the disease phenotype. Here, we show that TREX1, encoding the major mammalian 3' --> 5' DNA exonuclease, is the AGS1 gene, and AGS-causing mutations result in abrogation of TREX1 enzyme activity. Similar loss of function in the Trex1(-/-) mouse leads to an inflammatory phenotype. Our findings suggest an unanticipated role for TREX1 in processing or clearing anomalous DNA structures, failure of which results in the triggering of an abnormal innate immune response.