51 research outputs found

    GEOLOGICAL CHALLENGES IN HYDRAULIC FRACTURING OPERATION: A CASE STUDY IN UNDISCLOSED PETROLEUM FIELD IN OMAN

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    Production of hydrocarbons is hampered by obstacles known as formation damage. This damage needs to be removed or bypassed to retain well productivity. Hydraulic fracturing stimulation is one of the techniques used to overcome formation damage and enhance the productivity of the formation by maximizing the ultimate recovery. It was highlighted that there are some challenges associated with this technique and the most difficult challenges in hydraulic fracturing design and implementation are those related to geology of the reservoir. This study was, therefore, aimed at addressing the main geological challenges and providing the best low-cost solution and practice that leads to easy and successful stimulation operation. As an engineering solution in this study, fracturing geometry design was addressed to overcome geological challenges using advance simulator tool. Multiple fracking design by using computer simulation for a set of geological parameters aid on predicting the result out and avoid any complication in future production. Other challenges addressed by intelligent numerical evaluation used as a best practice in well stimulation to maximize the benefits of well production recovery. Optimizing fracturing fluid is also an important element covered in this study. An investigation was conducted on formation permeability variation for heterogeneous rock formation as one of the geological challenges faced by hydraulic fracturing operation for further understanding the geometry of fracturing for the success of stimulation operation. By fixing all other formation and pumping variables it was observed that formation permeability influences the length of fracture geometry, which could lead to stimulate out of pay zone

    The sun is no fun without rain : Physical environments affect how we feel about yellow across 55 countries

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    Across cultures, people associate colours with emotions. Here, we test the hypothesis that one driver of this cross-modal correspondence is the physical environment we live in. We focus on a prime example – the association of yellow with joy, – which conceivably arises because yellow is reminiscent of life-sustaining sunshine and pleasant weather. If so, this association should be especially strong in countries where sunny weather is a rare occurrence. We analysed yellow-joy associations of 6625 participants from 55 countries to investigate how yellow-joy associations varied geographically, climatologically, and seasonally. We assessed the distance to the equator, sunshine, precipitation, and daytime hours. Consistent with our hypotheses, participants who live further away from the equator and in rainier countries are more likely to associate yellow with joy. We did not find associations with seasonal variations. Our findings support a role for the physical environment in shaping the affective meaning of colour.Peer reviewe

    Large expert-curated database for benchmarking document similarity detection in biomedical literature search

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    Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

    The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

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    INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

    Validation of the Malay version of the multidimensional scale of perceived social support (MSPSS-M) among a group of medical students in Faculty of Medicine, University Malaya

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    Objective: The aim of this study was to validate the Malay version of the Multidimensional Scale of Perceived Social Support (MSPSS-M) among a group of medical students in Faculty of Medicine, University Malaya. Methods: 237 students participated in the study. They were given the Malay version of MSPSS, medical outcome study (MOS) social support survey, Malay version of General Health Questionnaire (GHQ), Malay version of Beck Depression Inventory (BDI) and English version of MSPSS. A week later, these students were again given the Malay version of MSPSS. Results: The instrument displayed good internal consistency (Cronbach's alpha = 0.89), parallel form reliability (0.94) and test�retest reliability (0.77) (Spearman's rho, p < 0.01). The negative correlation of the total and subscales of the instrument with the Malay version of GHQ and BDI confirmed its validity. Extraction method of the 12 items MSPSS using principle axis factoring with direct oblimin rotation converged into three factors of perceived social support (Family, Friends and Significant Others) with reliability coefficients of 0.88, 0.82 and 0.94, respectively. Conclusion: The Malay version of the MSPSS demonstrated good psychometric properties in measuring social support among a group of medical students from Faculty of Medicine, University Malaya and it could be used as a simple instrument on young educated Malaysian adolescents

    Assessing Heavy Metal Pollution Hazard in Sediments of Lake Mariout, Egypt

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    International audienceThe Cd, Cr, Cu, Ni, and Pb concentrations in the sediments of Lake Mariout were measured and estimated by statistical approaches using the contamination factor (CF), pollution load index (PLI), geo-accumulation index (I-geo), Nemerow index (I-in), ecological hazard index, and potential ecological hazard index (RI). The aim of the present work was to assess the current situation of Lake Mariout compared with other Egyptian lakes regarding heavy metal pollution in the sediment and to identify the putative sources. The measured concentration levels of heavy metals in Lake Mariout sediments were higher than the geochemical background reference condition by a factor of two to three, except for sediment sampled near the Umoum drain, where metal concentrations were close to the geochemical background reference condition. The PLI ranged from moderately to heavily polluted classes. The I-geo ranged from uncontaminated to moderately contaminated classes, where the RI indicates a low hazard. The comparison of Lake Mariout with other lakes indicates that all heavy metal concentrations except for Cd in Lake Mariout were higher than the average concentrations in Edku Lake. However, the average concentrations of Cd and Ni in Burullus Lake were higher than those found in the current study. For Manzala Lake, the Cd, Cu, and Pb concentrations were higher than the measured concentrations in Lake Mariout. The environmental hazard assessments of heavy metal concentrations in the Lake Mariout sediment determined the prevalence of possible anthropogenic pollution sources near the East and West Wastewater Treatment Plants and the El-Max pumping station

    Radiometric Dating of Wadi Zarqa Ma’in 1, a Limestone Sinkhole Natural Faunal Trap near the Dead Sea, Using Data from Test Pitting and a Portable Coring System

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    The natural faunal trap site of Wadi Zarqa Ma’in 1 (WZM-1) is located ten kilometers southwest of the city of Madaba in Jordan (fig. 1), near the Dead Sea (N 31o 37\u27 17.0\u27\u27,E 35o 43\u27 00.6\u27\u27) and approximately 730 m above mean sea level. The limestone sinkhole, resulting from karst dissolution processes, measures over 30 m in maximum depth and is a significant source in the region of faunal, microbotanical, and sedimentological data recording paleoecology and paleoenvironmental change. Along several approaches, the sinkhole is not readily visible, and the initial fall is usually fatal to large mammals. Egress is not possible for most vertebrate species that do survive the fall due to high, overhanging walls. The accumulation of fresh animal carcasses at the base of the feature is an additional attractant, as this food resource may entice scavengersto attempt to enter the sinkhole voluntarily (Friscia et al. 2008). How long this sinkhole existed in a configuration similar to the present (a large, open pit) is unknown, but its large size and the depth of the known deposits indicate a functional life likely well into the Pleistocene. The talus deposits accumulating at the base of WZM-1 have an exposed minimum depth of over 10 m, with the maximum depth currently unknown and likely much greater. The presence of Middle Paleolithic stone tools in low densities around WZM-1 suggests that the limestone feature could have been used by hominins, although not in its current configuration

    Caffeine addiction and determinants of caffeine consumption among health care providers: a descriptive national study

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    OBJECTIVE: Caffeine is the most commonly used psychostimulant compound with a long history of worldwide consumption. Consuming low to moderate doses of caffeine is generally safe and quite beneficial; however, several clinical studies show that high doses could be toxic.  Additionally, caffeine users can become dependent on the drug and find themselves unable to reduce consumption despite impending and recurrent health problems associated with continued use. This study was conducted to explore the prevalence, determinants, and positive and negative effects of caffeine consumption among governmental health care providers (HCPs) who were caffeine users. It aims to determine the frequency of caffeine dependence and addiction in the Kingdom of Saudi Arabia (KSA) in January 2020. SUBJECTS AND METHODS: This cross-sectional study recruited 600 randomly selected HCPs from all regions of KSA, who fulfilled the selection criteria through a self-administrated, online-validated questionnaire composed of three main parts using the DSM-IV to diagnose dependence and probable addiction. RESULTS: The majority of the studied HCPs were females (67.8%), nonsmokers (82.0%), and Saudis (80.5%), with a mean age of 35 years. According to the DSM-IV, the prevalence of caffeine consumption was 94.3%. Caffeine dependence was reported in 270 (47.7%), while 345 (60.9%) were diagnosed as addicts. The most commonly consumed caffeine-containing substances were coffee and its variants/types (70%), tea (59%), and chocolate (52%), with each person spending about 220 SR per week on them. The main reported adverse effects, in descending order, were sleep disturbances, stomach problems, and cardiac symptoms. The most positive effects reported of caffeine consumption were feeling active, alert, confident, and happy. These findings were significantly affected by sex, occupation, and general health. CONCLUSIONS: Caffeine use, dependence, and addiction are common among government HCPs in KSA. Caffeine has both positive and negative effects on this population and further research is necessary to better understand the long-term consequences of caffeine consumption
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