106 research outputs found

    The Habitability of the Galactic Bulge

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    We present a new investigation of the habitability of the Milky Way bulge, that expands previous studies on the Galactic Habitable Zone. We discuss existing knowledge on the abundance of planets in the bulge, metallicity and the possible frequency of rocky planets, orbital stability and encounters, and the possibility of planets around the central supermassive black hole. We focus on two aspects that can present substantial differences with respect to the environment in the disk: (i) the ionizing radiation environment, due to the presence of the central black hole and to the highest rate of supernovae explosions and (ii) the efficiency of putative lithopanspermia mechanism for the diffusion of life between stellar systems. We use analytical models of the star density in the bulge to provide estimates of the rate of catastrophic events and of the diffusion timescales for life over interstellar distances.Comment: Published in Lif

    Terrorism and the military institution: History and Definitions

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    Recent narratives on terrorism have focused on the definitions. Terrorism is not a new phenomenon but the problem resides in its definition and who is defining it. Conceptualizing terrorism depends on which framework one utilizes. The use of different lenses to define a crime has contributed to lack of global acceptance of what constitutes terrorism hence the difficulty of gathering data for analysis. It is also a conundrum when a powerful nation legitimizes its terrorist activities against a weaker one through the use of military power. This, unfortunately, has led to the subjectiveness of every attempt in the literature to objectively provide a globally acceptable definition. This article looks at a brief history of the military as an institution and how it has been, and continues to be used as an instrument of terror by political leaders. The paper questions the activities of the military and concludes we are all guilty of terrorism

    Outbreak of gastroenteritis caused by Yersinia pestis in Afghanistan.

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    Plague, which is most often caused by the bite of Yersinia pestis-infected fleas, is a rapidly progressing, serious disease that can be fatal without prompt antibiotic treatment. In late December 2007, an outbreak of acute gastroenteritis occurred in Nimroz Province of southern Afghanistan. Of the 83 probable cases of illness, 17 died (case fatality 20·5%). Being a case was associated with consumption or handling of camel meat (adjusted odds ratio 4·4, 95% confidence interval 2·2-8·8, P<0·001). Molecular testing of patient clinical samples and of tissue from the camel using PCR/electrospray ionization-mass spectrometry revealed DNA signatures consistent with Yersinia pestis. Confirmatory testing using real-time PCR and immunological seroconversion of one of the patients confirmed that the outbreak was caused by plague, with a rare gastrointestinal presentation. The study highlights the challenges of identifying infectious agents in low-resource settings; it is the first reported occurrence of plague in Afghanistan

    Formulation and characterization of self compacting concrete with silica fume

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    Self-compacting concrete (SCC) was elaborated using local materials and silica fume (SF) as admixture in 15% of cement quantity, two different Portland cements (PC) and two different superplasticizer that the chemical nature is polycarboxylate and plynaphtalene, the aggregates used are (AG 3/8 mm, AG 8/15 mm), coarse and fine sand (SC, SF) witch fineness modulus 3.2 and 1 in the order. The dosage of the different superplasticizer used is chosen after experimental spreading tests of each self compacting concrete formulation. Results of fresh concrete tests executed, as L-box and segregation resistance are on concordance whit values recommended by the French association of civil engendering. Also the mechanical characterization was conducted by compressive strength and splitting compression testing procedure, results values are in the range higher than 20 Mpa at the seven day by the compressive test for the all compositions, and the highest value was 40.93 MPa at the 28 day bay compressive test of the fourth’s formulation specimens, the values of splitting compressive tests of al formulation specimens at 7, 14 and 28 days, was situated between 2.01 and 4.40 MPa. In order to determine the superplasticizer saturation assay in of cement pasts used in self compacting concrete, the stady was completed by a rheological stady with a variable velocity gradient, so as to estimate the quantity of saturation assay of superplasticizer and the formulation, also the flow models of cement past

    Study on biological status of the Gorgan Bay

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    Present study carried out between September 2011 and October 2012 in 19 sampling sites in order to investigate the trophy level, productivity, and natural dominant living conditions in the Gorgan Bay. According to the provided maps from the shoreline, depth, and sediment, the total area and volume of Gorgan Bay is 466 square meters and 905.33 million cubic meters respectively. Also the physic-chemical parameters including: water temperature, EC, salinity, transparency, DO, BOD_5, pH, Ammonia, Nitrate, Total hardness, Total alkalinity, and phosphate are determined and studies. 3 main phylum, 12 orders, 6 classes, and 12 families from bottom living organisms (macro-benthos) were identified in this region. Standard deviation in TSI was from minimum 37 in March up to maximum 65 in September and the annual average was 53. According to the average TSI in different months, for five months namely as March, April, June, August, and February the dominant situation was eutrophy. For the rest of months namely as May, September, October, November, December, and January the dominant situation was Meso-trophic in the Bay. Based on calculation, minimum and maximum productivity in the Bay were 92.26 and 700.66 Kg per hectare in October and July respectively. The annual average of productivity was 195.10 Kg per hectare

    Ecological study on fisheries important rivers and bays in the south part of the Caspian Sea 2nd phase: Gorgan Bay

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    In this study ichthyoplankton, phytoplankton, zooplankton, benthic and hydrochemistry parameters were studied. 9 out of 11 sampling stations were in the Gorgan Bay area and 2 of them were in the mouth of the Bay. Ichthyoplankton survey were carried out in 6 stations and the other surveys such as phytoplankton, etc were done in 11 stations in 2009. Gorgan Bay map and position of sampling sites are given at the end of material and methods section. Biomass and frequency of phytoplankton at different stations, months and seasons were calculated that are presented in Tables 1 to 3. Hydro-chemical parameters such as water temperature, air temperature, visibility, DO, BOD5, pH, Alkalinity (bicarbonate, carbonate and total), Hardness (calcium, magnesium), CL,EC, Salinity, N (nitrate, nitrite, NH_3), Phosphate were measured and results are shown Table 11. Biomass (mgr/m^3) and numbers (ind./m^3) of 47 genus of different phylum of phytoplanktons such as Cyanophyta, Chlorophyta, Pyrophyta, Chrysophyta and Euglenaphyta as well as different phylum of zooplanktons consist of Protozoa, Arthropoda, Rotifera and Cyliophora were estimated. Frequency of phytoplanktons (ind/m^3) was 131.2, 1.6, 65.3, 18.9 and 23.8 million respectively. Furthermore, their biomass was 308.4, 1.9, 1358.9, 295.1 and 124.7 mg/m^3, respectively. The maximum and minimum numbers were observed in Leptolingbaya belonged to Cyanophyta and Diatoms of Chrysophyta 84.3 and 0.025 million (ind/ m^3) respectively. The maximum and minimum biomass was observed in Gyrosigma (Chrysophyta) and Tetradron (Chloropyta), 12317.3 and 0.014 mg/m3 respectively. The average biomass of zooplankton was measured 531.74, 30.77, 225.07, and 96.26 mg/m^3 respectively and the total was attained 883.83 mg/m3 Table 5. The maximum and minimum biomass of all zooplanktons was estimated in November and July, 3446.23 and 6 mg/m^3 respectively. Furthermore, the maximum and minimum numbers of zooplanktons were found in September and July which were 48.4 and 0.002 millions respectively and the average number was 8.4 ind/m^3 Table 4. Also numbers and biomass (gr/m^2) of 11 families of benthos which inhabit Gorgan Bay such as Annelida, Mollusca and Arthropoda were investigated in separated stations and distinctive months. The maximum and minimum biomass of benthos was observed in January (42.91 gr/m^2) and March (0.6428 gr/m^2). The biomass was considerable in April, February, August and December (Tables: 4, 5 and 6)

    Study of penculture of the common carp (Cyprinus carpio L.) fingerlings at the Gorgan Bay to the maturity stage (broodstock management)

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    The aim of present project is study on the possibilities of brood stock production from fingerlings in the penculture condition and the effect of density on it .this project was done during three years with two different treatment and three repetitions in the Gorgan Bay. First treatment with two fingerlings per square meter and the 2nd with four fingerlings per square meter in each pen.To carry out the project at first fingerlings were brought from breeding and recruitment centre –Sijeval (Kolmeh) and the stocked at the earthen pound with concentrated food .After that they were adaptated with brakish water between 7-10 days and transferred to Gorgan Bay for cultivation with average weight of 93.78±32.66 grams and 20.53±2.37 cm in length. It should be noted that 6 pens (which surrounded by nets in the water) were fixed using mast with 15-20 cm in diameter and 5.5 meter in length , Net mesh size was 16 mm with string number 33 of kapron.Feeding was done according to the program two times by giving concentrated food at the period of cultivation Physic -o -chemical factors were measured. biometery was done monthly at each pen and other fishes (unwanted) were observed at the same time. results indicate that in the 1st and 2nd treatments average survival rate was 52.3 and 41 percent respectively with average weight of 410±64.98 grams and 390±52.8 and 28.3±1.79 cm and 27.66±1.57in length. SPSS used to analysethe data such as average length and weight of fish in the treatments and in different months with ANOVA method (p≤ 0.05) . results show that there is no significant difference between treatments. Autopsy observation also showed that fishes (female and male) are mature and histological studies showed that most of observed eggs are entirely mature with 800-1200 micron diameter gonad ( male) were mature at the pen in the Gorgan Bay condition .The male and female hormones were evaluated. 17-B- Estradiol and 11-keto testosterone hormones for adult fish (female and male) parents respectively are similar in dense with those adult fish before injection to use at the artificial breeding. Maturation were verified by autopsy, histology and hormone studies

    Intragenic suppressors of temperature-sensitive rne mutations lead to the dissociation of RNase E activity on mRNA and tRNA substrates in Escherichia coli

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    RNase E of Escherichia coli is an essential endoribonuclease that is involved in many aspects of RNA metabolism. Point mutations in the S1 RNA-binding domain of RNase E (rne-1 and rne-3071) lead to temperature-sensitive growth along with defects in 5S rRNA processing, mRNA decay and tRNA maturation. However, it is not clear whether RNase E acts similarly on all kinds of RNA substrates. Here we report the isolation and characterization of three independent intragenic second-site suppressors of the rne-1 and rne-3071 alleles that demonstrate for the first time the dissociation of the in vivo activity of RNase E on mRNA versus tRNA and rRNA substrates. Specifically, tRNA maturation and 9S rRNA processing were restored to wild-type levels in each of the three suppressor mutants (rne-1/172, rne-1/186 and rne-1/187), while mRNA decay and autoregulation of RNase E protein levels remained as defective as in the rne-1 single mutant. Each single amino acid substitution (Gly→Ala at amino acid 172; Phe → Cys at amino acid 186 and Arg → Leu at amino acid 187) mapped within the 5′ sensor region of the RNase E protein. Molecular models of RNase E suggest how suppression may occur
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