635 research outputs found
Strategic alliance in energy sector & implications for economic growth and technical efficiency: The case of petrobras and galp
This study stemmed from the lack of evidence and uncertainties regarding the economic and political effects of a strategic alliance between leading oil companies like Petrobras and Galp on their host economies. This paper investigates whether public and private corporations in the energy sector can influence the economic growth of their respective countries. A Panel data analysis was performed by employing quarterly data from (2006-2013). We also used Data Envelopment Analysis (DEA) approach to measure the technical efficiency (TE) effect of the alliance on the performance of both companies from 1999 to 2012. It was found the exploration and export of oil and gas do not play a significant role in output growth of the home economy and that exploration activities were inflationary, destabilising and inimical to growth, at least in the short-run. On another positive side, both companies showed increased technical efficiencies in the chosen time period. Petrobras enjoyed TE on average of 90% in the variables studied whereas Galp showed an average TE of 70%. These results reflect the corporate strategies of both firms, which focussed on achieving profitable and sustained growth and enhancing their efficiencies in their collective and individual activities
Mechanisms of redundancy and specificity of the Aspergillus fumigatus Crh transglycosylases
Transglycosylases strengthen the fungal cell wall by forming a rigid network of crosslinks. Here, Fang et al. show that the five Crh transglycosylases of Aspergillus fumigatus are dispensable for cell wall integrity in vitro, and solve the crystal structure of Crh5 in complex with chitooligosaccharides
Real-Time PCR Improves Helicobacter pylori Detection in Patients with Peptic Ulcer Bleeding
Background and aims: Histological and rapid urease tests to detect H. pylori in biopsy specimens obtained during peptic ulcer bleeding episodes (PUB) often produce false-negative results. We aimed to examine whether immunohistochemistry and real-time PCR can improve the sensitivity of these biopsies. Patients and Methods: We selected 52 histology-negative formalin-fixed paraffin-embedded biopsy specimens obtained during PUB episodes. Additional tests showed 10 were true negatives and 42 were false negatives. We also selected 17 histology-positive biopsy specimens obtained during PUB to use as controls. We performed immunohistochemistry staining and real-time PCR for 16S rRNA, ureA, and 23S rRNA for H. pylori genes on all specimens. Results: All controls were positive for H. pylori on all PCR assays and immunohistochemical staining. Regarding the 52 initially negative biopsies, all PCR tests were significantly more sensitive than immunohistochemical staining (p<0.01). Sensitivity and specificity were 55% and 80% for 16S rRNA PCR, 43% and 90% for ureA PCR, 41% and 80% for 23S rRNA PCR, and 7% and 100% for immunohistochemical staining, respectively. Combined analysis of PCR assays for two genes were significantly more sensitive than ureA or 23S rRNA PCR tests alone (p<0.05) and marginally better than 16S rRNA PCR alone. The best combination was 16S rRNA+ureA, with a sensitivity of 64% and a specificity of 80%. Conclusions: Real-time PCR improves the detection of H. pylori infection in histology-negative formalin-fixed paraffin-embedded biopsy samples obtained during PUB episodes. The low reported prevalence of H. pylori in PUB may be due to the failure of conventional tests to detect infection
First GIS analysis of modern stone tools used by wild chimpanzees (Pan troglodytes verus) in Bossou, Guinea, West Africa
Stone tool use by wild chimpanzees of West Africa offers a unique opportunity to explore the evolutionary roots of technology during human evolution. However, detailed analyses of chimpanzee stone artifacts are still lacking, thus precluding a comparison with the earliest archaeological record. This paper presents the first systematic study of stone tools used by wild chimpanzees to crack open nuts in Bossou (Guinea-Conakry), and applies pioneering analytical techniques to such artifacts. Automatic morphometric GIS classification enabled to create maps of use wear over the stone tools (anvils, hammers, and hammers/anvils), which were blind tested with GIS spatial analysis of damage patterns identified visually. Our analysis shows that chimpanzee stone tool use wear can be systematized and specific damage patterns discerned, allowing to discriminate between active and passive pounders in lithic assemblages. In summary, our results demonstrate the heuristic potential of combined suites of GIS techniques for the analysis of battered artifacts, and have enabled creating a referential framework of analysis in which wild chimpanzee battered tools can for the first time be directly compared to the early archaeological record.Leverhulme Trust [IN-052]; MEXT [20002001, 24000001]; JSPS-U04-PWS; FCT-Portugal [SFRH/BD/36169/2007]; Wenner-Gren Foundation for Anthropological Researc
关于《现代汉语词典》词汇计量研究的思考
A Dictionary of Modern Chinese is standardized dictionary of words in Chinese Putonghua. The establishment of a database of DMC for a quantitative study of its entries as a closed, exhaustive and specific body will change significantly the situation of lacking quantitative analysis in traditional lexical study, so that to help the systemization and accuracy of the study of Chinese lexicology and lexicography. This paper expounds the point of departure, ways and methodology and perspective in theory a..
Terrestrial Snakebites in the South East of the Arabian Peninsula: Patient Characteristics, Clinical Presentations, and Management
Background: To describe the characteristics, clinical presentations, management and complications of snakebites in the border region between Al-Ain, United Arab Emirates (UAE) and Buraimi, Sultanate of Oman. Methodology/Principal Findings: We carried out a retrospective review of medical records to study snakebite cases over four-year duration at three tertiary hospitals. Overall, 64 snakebite cases were studied with median hospitalization of 2 (interquartile range [IQR] 1–4) days. The majority of cases were male (87.5%), and most (61%) of the incidents occurred during summer months. The bite sites were predominantly (95%) to the feet and hands. Main clinical features included pain, local swelling, and coagulopathy, blistering and skin peeling. Overall, there were no deaths, but few major complications occurred; extensive skin peeling (n = 5, 8%), multi-organ failure (n = 1, 1.5%), and compartment syndrome (n = 1, 1.5%). Polyvalent anti snake venom (ASV), analgesia, tetanus toxoid, intravenous fluids, and antibiotics such as ampicillin, cloxacillin, and cephalosporins were commonly instituted as part of treatment protocols in the three hospitals. Conclusion: The overwhelming majority of bites occurred during summer months, and envenomations were more common in, relatively, young male farmers, but with no serious clinical complications. Prevention and treatment strategies should include increasing public awareness, developing management guidelines, and manufacturing specific ASV for a wid
Cytosolic Superoxide Dismutase (SOD1) Is Critical for Tolerating the Oxidative Stress of Zinc Deficiency in Yeast
Zinc deficiency causes oxidative stress in many organisms including the yeast Saccharomyces cerevisiae. Previous studies of this yeast indicated that the Tsa1 peroxiredoxin is required for optimal growth in low zinc because of its role in degrading H2O2. In this report, we assessed the importance of other antioxidant genes to zinc-limited growth. Our results indicated that the cytosolic superoxide dismutase Sod1 is also critical for growth under zinc-limiting conditions. We also found that Ccs1, the copper-delivering chaperone required for Sod1 activity is essential for optimal zinc-limited growth. To our knowledge, this is the first demonstration of the important roles these proteins play under this condition. It has been proposed previously that a loss of Sod1 activity due to inefficient metallation is one source of reactive oxygen species (ROS) under zinc-limiting conditions. Consistent with this hypothesis, we found that both the level and activity of Sod1 is diminished in zinc-deficient cells. However, under conditions in which Sod1 was overexpressed in zinc-limited cells and activity was restored, we observed no decrease in ROS levels. Thus, these data indicate that while Sod1 activity is critical for low zinc growth, diminished Sod1 activity is not a major source of the elevated ROS observed under these conditions
Diagnosis of Human Visceral Pentastomiasis
Visceral pentastomiasis in humans is caused by the larval stages (nymphs) of the arthropod-related tongue worms Linguatula serrata, Armillifer armillatus, A. moniliformis, A. grandis, and Porocephalus crotali. The majority of cases has been reported from Africa, Malaysia, and the Middle East, where visceral pentastomiasis may be an incidental finding in autopsies, and less often from China and Latin America. In Europe and North America, the disease is only rarely encountered in immigrants and long-term travelers, and the parasitic lesions may be confused with malignancies, leading to a delay in the correct diagnosis. Since clinical symptoms are variable and serological tests are not readily available, the diagnosis often relies on histopathological examinations. This laboratory symposium focuses on the diagnosis of this unusual parasitic disease and presents its risk factors and epidemiology
Mite community composition across a European transect and its relationships to variation in other components of soil biodiversity
The sustainable use of soils requires the protection of soil biodiversity because of its importance in the delivery of ecosystems services. However, no effective indicator exists which would allow assessment of the current state of biodiversity and is sensitive to change. This study, which is a component of the EcoFINDERS project, examines the use of mites (Acari) as a possible biological indicator of soil community composition. Thirty-six sites were sampled across 10 European countries spanning four bio-climatic zones (Alpine, Atlantic, Continental and Mediterranean) and 3 land uses (arable, grassland and forestry) for both biotic and abiotic variables. Results show a significant effect of bio-climatic zone on mite communities; in particular, the Mediterranean region had a rather distinct composition. Land use type significantly affected mite community composition and there was a distinct association with forestry. Cross-taxon congruence among soil taxa was variable and generally weak. Procrustes analysis showed that there was little similarity between the patterns of variation in mite community composition and those of other taxonomic groups (Collembola, Enchytraeidae, Nematoda and microbes). Mite and Collembola communities had the strongest correlation ( r= 0.4316, p</p
First observations of separated atmospheric nu_mu and bar{nu-mu} events in the MINOS detector
The complete 5.4 kton MINOS far detector has been taking data since the beginning of August 2003 at a depth of 2070 meters water-equivalent in the Soudan mine, Minnesota. This paper presents the first MINOS observations of nuµ and [overline nu ]µ charged-current atmospheric neutrino interactions based on an exposure of 418 days. The ratio of upward- to downward-going events in the data is compared to the Monte Carlo expectation in the absence of neutrino oscillations, giving Rup/downdata/Rup/downMC=0.62-0.14+0.19(stat.)±0.02(sys.). An extended maximum likelihood analysis of the observed L/E distributions excludes the null hypothesis of no neutrino oscillations at the 98% confidence level. Using the curvature of the observed muons in the 1.3 T MINOS magnetic field nuµ and [overline nu ]µ interactions are separated. The ratio of [overline nu ]µ to nuµ events in the data is compared to the Monte Carlo expectation assuming neutrinos and antineutrinos oscillate in the same manner, giving R[overline nu ][sub mu]/nu[sub mu]data/R[overline nu ][sub mu]/nu[sub mu]MC=0.96-0.27+0.38(stat.)±0.15(sys.), where the errors are the statistical and systematic uncertainties. Although the statistics are limited, this is the first direct observation of atmospheric neutrino interactions separately for nuµ and [overline nu ]µ
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