Rajesh Varma
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5017 research outputs found
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Drilling speed-up and production-increasing development practice of ultra deep clastic reservoir based on Geology-Engineering integration in the Tarim Basin, Northwest China
No full textKelasu structural belt in Tarim Basin has a large reservoir burial depth and complex geological conditions, and challenges such as ultra-deep, high temperature, high pressure, and high stress lead to big problems related to well control safety and project quality. To solve these key technical problems that set barriers to the process of exploration and development, a set of drilling technology processes via geology-engineering integration is established with geomechanics as the bridge. And an integrated key drilling engineering technology for the safe speed-up of ultra-deep wells was formed, integrating well location optimization, well trajectory optimization, stratum pressure prediction before drilling, stratum drillability evaluation, and bit and speed-up tool design and optimization. Combined with seismic data, logging data, structural characteristics, and lithology distribution characteristics, the rock mechanics data volume related to the three-dimensional drilling resistance characteristics of the block was established for the first time, and the vertical and horizontal heterogeneity was quantitatively characterized, which provided a basis for bit design, improvement, and optimization. During the process of drilling, the geomechanical model shall be corrected in time according to the actual drilling information, and the drilling “three pressures” data shall be updated in real-time to support the dynamic adjustment of drilling parameters. Through field practice, the average drilling complexity rate was reduced from 18% to 4.6%, and the drilling cycle at 8500 m depth was reduced from 326 days to 257 days, which were significantly better than those of the vertical wells deployed in the early stage without considering geology-engineering integration.</p
Nutrition cycles in sessile oak (<i>Quercus petraea Liebl</i>.), Norway spruce (<i>Picea abies L.Karst</i>) and European beech (<i>Fagus sylvatica L.</i>) stands from Central Romania
No full textIn Romania, the sessile oak is the widest spread species of all native oak species, forming a lower story of vegetation. The European beech and Norway spruce cover 50% of the Romanian forest area. The purpose of this study was to analyze the variability of the leaf nutrients, as well as of the soil nutrients, for sessile oak, Norway spruce and European beech stands situated under different site conditions. The studied sites are located in the southern part of the Carpathian Mountains at altitudes varying from 600 m to 1300 m. Leaves samples were collected from twenty sessile oak trees, in three moments during the growing season. The same eight elements in total form were determined for soil and leave too: N, P, K, Ca, Mg, Fe, Cu and Zn. Leaves samples for beech and spruce were collected in the II Level Intensive Monitoring Grid of the ICP Forests Programme. The paper focuses on the seasonal concentration variation of eight macro elements in leaves and the correlations between the concentration of the macro elements in soil and litter. In addition, the study highlighted the degree of influence exerted by some soil properties on the foliar concentration of nutrients (through multiple regressions). The obtained results show different mobility of the elements and a greater variability was noticed in the case of certain elements. The same three soil properties were noticed to influence the foliar nitrogen concentration. </p
The effect of olfactory exposure on the heart rate of rabbits during transport
No full textSummaryRabbits can experience stress during transport. This study explores the effects of Essential Oils (EOs) on the heart rate of rabbits during transport. Rabbits were submitted to 3 different treatments: no olfactory exposure to EOs (treatment 1, control); olfactory exposure to 30 drops of Lavandula angustifolia EO (treatment 2); and olfactory exposure to 30 drops of a blend of 5 EOs (treatment 3, Cananga odorata, Citrus aurantium, Cupressus sempervirens, Lavandula angustifolia, Litsea citrata EOs) in a randomized controlled crossover study design. Treatment 1 and Treatment 2 did not induce a significant change in rabbits’ heart rates, however, treatment 3 did induce a significant decrease in rabbits’ heart rates after transport. These results suggest that olfactory exposure to this blend of 5 EOs decreased the rabbit’s heart rate after transport. More research is needed to further evaluate the effects of olfactory enrichment with EOs in rabbits during transport.AbstractThe study explores the effects of Essential Oils (EOs) on the heart rate of rabbits during transport. Rabbits (n = 35) were individually transported three times by car in a transport box for 5 minutes. Each rabbit was subjected to three treatments: no olfactory exposure to EOs (treatment 1, control); olfactory exposure to 30 drops of Lavandula angustifolia EO (treatment 2); and olfactory exposure to 30 drops of a blend of 5 EOs (treatment 3, Cananga odorata, Citrus aurantium, Cupressus sempervirens, Lavandula angustifolia, Litsea citrata EOs) in a randomized controlled crossover study design. Heart rate was measured before and after transport. Compared to the control, treatment 3 showed a significant decrease in HR after transport (mean = -24.33, SD = 41.77; post hoc Tukey test p = 0.007). Results suggest that the blend of EOs might help rabbits to recover homeostasis quicker after a stressful event. This suggests interesting potential field applications not only for rabbit owners but also for veterinarians. There is more research needed regarding the specific effects of EOs on rabbits.</p
OG-SLAM: A real-time and high-accurate monocular visual SLAM framework
No full textThe challenge of improving the accuracy of monocular Simultaneous Localization and Mapping (SLAM) is considered, which widely appears in computer vision, autonomous robotics, and remote sensing. A new framework (ORB-GMS-SLAM (or OG-SLAM)) is proposed, which introduces the region-based motion smoothness into a typical Visual SLAM (V-SLAM) system. The region-based motion smoothness is implemented by integrating the Oriented Fast and Rotated Brief (ORB) features and the Grid-based Motion Statistics (GMS) algorithm into the feature matching process. The OG-SLAM significantly reduces the absolute trajectory error (ATE) on the key-frame trajectory estimation without compromising the real-time performance. This study compares the proposed OG-SLAM to an advanced V-SLAM system (ORB-SLAM2). The results indicate the highest accuracy improvement of almost 75% on a typical RGB-D SLAM benchmark. Compared with other ORB-SLAM2 settings (1800 key points), the OG-SLAM improves the accuracy by around 20% without losing performance in real-time. The OG-SLAM framework has a significant advantage over the ORB-SLAM2 system in that it is more robust for rotation, loop-free, and long ground-truth length scenarios. Furthermore, as far as the authors are aware, this framework is the first attempt to integrate the GMS algorithm into the V-SLAM.</p
About Segmath, a new Cerebral Vascular Segmentation Software after CTA
No full textObjectives: The new segmentation software Segmath delivers a 3D view of the cerebral vascular structures without superposition of bony or other structures. This will, according to the literature, improve the workflow of stroke patients and increase the occlusion detection rate on the original CTA.Materials and methods: The software written in MATLAB is based on the analysis of the local Hessian matrix with new original functions of the resulting local eigenvalues. No user intervention in the segmentation process is needed.Results: The validation of the new software yields good results both with synthetic data and real CTA’s. Conclusion: This segmentation software is a powerful additional diagnostic tool available to radiologists and neurologists examining and treating stroke patients. This will improve the workflow of suspected stroke patients.</p
The resistance of leds to the effects of gamma radiation in various operating modes
No full textThe effect of active and passive power modes on the resistance of the LEDs (LEDs) made of multilayer AlGaAs heterostructures to gamma-quantum irradiation was studied. Three characteristic stages of emission power reduction during irradiation are distinguished for the studied LEDs irrespective of the power supply mode. When irradiating LEDs in the active power supply mode, two differently directed processes of changes in the emission power are observed. The assumption is made that the first process is caused by a decrease in the LED emission power due to the injection of appropriate radiation defects. The second process is caused by a partial recovery of the emission power due to radiation, radiation-thermal, and/or electrostimulated annealing of some of the defects created. The observed recovery of the emission power in the active power mode of the LED during irradiation significantly increases its resistance to gamma-ray irradiation.</p
Phenotypic characterization of bacterial isolates from marine waters and plastisphere communities of the Ross Sea (Antarctica)
No full textBackground: In aquatic environments, microbial biofilms are hot spots of microbial diversity, as well as a substrate for larval settlement of many invertebrate species. Examining the functional diversity of microorganisms in polar regions is a new and still unknown field of aquatic microbiology, that is attracting increasing interest for its significance in both scientific research and resources exploitation.The context and purpose of the study: In the framework of research aimed at studying microbial colonization occurring at Terra Nova Bay, culturable heterotrophic bacteria were quantified and characterized phenotypically at two study areas (Road Bay and Tethys Bay) with different environmental characteristics: the first one was close to Mario Zucchelli research station and impacted by anthropogenic pressure due to sewage wastes, while the second was exposed to salinity gradients due to glacier melting. In this context, artificial structures hosting plastic (polyvinyl chloride, PVC and polyethylene, PE) panels were deployed at -5 and -20m depths at each of the stations (one Impact and one Control) chosen per each study area. Water samples were contextually collected at the time of recovery of the plastic panels, namely after 12 months of deployment; at Road Bay, at the -5 m depth, a short-term experiment was also performed, with the recovery of the panels after 2.5 and 9 months of deployment. Bacterial strains were isolated in axenic culture both from water and biofilm matrices, and examined for their main phenotypical traits and functional diversity, through Gram staining, oxidase production, glucose fermentation and screened for enzymatic activity profiles (proteolytic, glycolytic and phosphatasic activities) using specific fluorogenic substrates.Results: Most of the bacterial isolates were Gram-negative, oxidase-positive and glucose-fermenting strains. Higher enzyme diversification was found in Road Bay at the site impacted by the sewage wastes from the research station, compared to the control site. A higher abundance of heterotrophic bacteria was detected on PVC compared to PE. Several pigmented strains, ascribable to Flavobacterium sp., were isolated from biofilm with respect to the ones isolated from the pelagic environment.Main findings: The screening of bacterial isolates for the production of hydrolytic enzymes revealed that proteolytic and phosphatase activities were a common metabolic trait of both water and biofilm-derived isolated. Microbes inhabiting Antarctica represent a very important and not completely known source of bioactive molecules with possibly multiple applications, from biomedicine to pharmaceutical, cosmetics, biodegradation, and so on.Conclusions: This is the first contribution to characterize phenotypically the bacteria colonizing the Ross Sea seabed in comparison with pelagic heterotrophic bacteria and to explore their metabolic abilities and the biotechnological potential of these microorganisms. The preliminary data regarding the metabolic profiles and composition of the microbial community have highlighted the plasticity of the microbial community, whose metabolism is modulated by the organic matter supplies found near the Mario Zucchelli Station.Brief summary: Heterotrophic bacteria in the waters and in the biofilm covering the surface of settlement panels in plastics deployed at sea for different time periods were studied in two bays of the Ross Sea, Road Bay and Tethys Bay. The main phenotypical characteristics of the bacterial isolates were examined. The production of hydrolytic enzymes makes microbial biofilms interesting sources of molecules with a potential applicative interest.Any potential implications: Bioprospecting research on polar microorganisms represents an attractive field of microbiology that is supported by increasing attention towards the discovery of hydrolytic enzymes as new active compounds having unexplored properties and applications.</p
Mental health during the COVID-19 epidemic: The role of social media
No full textCurrently, the COVID-19 pandemic is one of the major health issues in the world [1,2]. In December 2019, a population of patients with pneumonia of unknown etiology was found in Wuhan, China. Many of the first patients were associated with a local seafood shop and live wild animals [1]. Therefore, it was initially thought that the disease was transmitted from animal to human. But after closing the said shop, the number of infected cases increased and it seemed that the second method of transmission of this disease was human-to-human [3].</p
Managing vomiting in the third trimester of pregnancy during fixed prosthodontic treatment. A case report and review of the literature
No full textPregnancy is a specific and critical period in a woman’s life. Some pregnant women face difficulty when performing effective oral hygiene care due to pregnancy-related vomiting symptoms. A hypersensitive vomit reaction in the third trimester of pregnancy is not frequent and may prevent the dental provider from successfully completing critical clinical stages resulting in poor treatment outcomes. Once pregnant women suffer an unpleasant gag reflex experience in a dental office, they may become phobic, delaying or postponing their dental treatment.The purpose of this article is to report a case of a 32-year-old woman, primigravida in the third trimester of pregnancy (32 weeks), partially edentulous with an exaggerated vomiting reaction, focusing on successful clinical management using a simple but effective table salt technique and proper fixed prosthesis design, as also to discuss the etiology, clinical symptoms and consequences of vomiting associated with late pregnancy during the dental, especially prosthodontics , treatment in such cases.</p
Factors influencing value addition to cashew products processed in the South-East Zone, Nigeria: A multinomial logistic regression approach
No full textNigeria is a leading cashew producer, but this has not been reflected in the development of the downstream cashew value chain industry. The launch of the “Agriculture Promotion Policy (2016 – 2020)” document was designed to encourage value addition to export crops such as cashew as ways of creating jobs and wealth to value chain actors. However, it is still unclear why cashew processors are unable to exploit this opportunity to improve value addition to cashew. This makes it imperative that factors influencing value addition to cashew products in the South-East zone, Nigeria be analyzed. A cross-sectional survey design involving a structured questionnaire was used to obtain data from 353 randomly selected respondents from the South-East zone, Nigeria. The study found that income, access to market, product characteristics, and cost of cashew processing technology significantly influence value addition to cashew products in the two models, whereas government policy on cashew processing and market facilities were significant in the second model. The relative risk ratios for age, educational level, income, processing experience, access to market, distance to market, government policy on cashew processing and market facilities were > 1, suggesting the likelihood of processor’s preferring to add value to cashew kernel, and both cashew products as against cashew nut for any unit increase in these variables. This study provided vital insights about how the relative significance of these factors will aid policy analysts and decision-makers to determine which of the factors to focus on while developing specific policies for the cashew value chain industry.</p