With the emergence of industry 4.0, the oil and gas (O&G) industry is now considering a range of digital technologies to enhance productivity, efficiency, and safety of their operations while ...minimizing capital and operating costs, health and environment risks, and variability in the O&G project life cycles. The deployment of emerging technologies allows O&G companies to construct digital twins (DT) of their assets. Considering DT adoption, the O&G industry is still at an early stage with implementations limited to isolated and selective applications instead of industry-wide implementation, limiting the benefits from DT implementation. To gain the full potential of DT and related technological adoption, a comprehensive understanding of DT technology, the current status of O&G-related DT research activities, and the opportunities and challenges associated with the deployment of DT in the O&G industry are of paramount importance. In order to develop this understanding, this paper presents a literature review of DT within the context of the O&G industry. The paper follows a systematic approach to select articles for the literature review. First, a keywords-based publication search was performed on the scientific databases such as Elsevier, IEEE Xplore, OnePetro, Scopus, and Springer. The filtered articles were then analyzed using online text analytic software (Voyant Tools) followed by a manual review of the abstract, introduction and conclusion sections to select the most relevant articles for our study. These articles and the industrial publications cited by them were thoroughly reviewed to present a comprehensive overview of DT technology and to identify current research status, opportunities and challenges of DT deployment in the O&G industry. From this literature review, it was found that asset integrity monitoring, project planning, and life cycle management are the key application areas of digital twin in the O&G industry while cyber security, lack of standardization, and uncertainty in scope and focus are the key challenges of DT deployment in the O&G industry. When considering the geographical distribution for the DT related research in the O&G industry, the United States (US) is the leading country, followed by Norway, United Kingdom (UK), Canada, China, Italy, Netherland, Brazil, Germany, and Saudi Arabia. The overall publication rate was less than ten articles (approximately) per year until 2017, and a significant increase occurred in 2018 and 2019. The number of journal publications was noticeably lower than the number of conference publications, and the majority of the publications presented theoretical concepts rather than the industrial implementations. Both these observations suggest that the DT implementation in the O&G industry is still at an early stage.
The major obstacle to curing HIV infection is the persistence of cells with intact proviruses that can produce replication-competent virus. This HIV reservoir is believed to exist primarily in CD4+ ...T-cells and is stable despite years of suppressive antiretroviral therapy. A potential mechanism for HIV persistence is clonal expansion of infected cells, but how often such clones carry replication-competent proviruses has been controversial. Here, we used single-genome sequencing to probe for identical HIV sequence matches among viruses recovered in different viral outgrowth cultures and between the sequences of outgrowth viruses and proviral or intracellular HIV RNA sequences in uncultured blood mononuclear cells from eight donors on suppressive ART with diverse proviral populations. All eight donors had viral outgrowth virus that was fully susceptible to their current ART drug regimen. Six of eight donors studied had identical near full-length HIV RNA sequences recovered from different viral outgrowth cultures, and one of the two remaining donors had identical partial viral sequence matches between outgrowth virus and intracellular HIV RNA. These findings provide evidence that clonal expansion of HIV-infected cells is an important mechanism of reservoir persistence that should be targeted to cure HIV infection.
Background and purpose
Our aim was to study the quality of the literature search strategies used in recent systematic reviews and to develop and assess the diagnostic accuracy of six new search ...strategies (i.e. hedges).
Methods
Six neurological conditions were studied: migraine, stroke, dementia, epileptic seizures, Parkinson's disease and multiple sclerosis. Two reviewers independently assessed the quality of the search strategies used in systematic reviews published in 2015–2016. Complex hedges pertaining to the six conditions for use in Ovid MEDLINE were developed. Their diagnostic accuracy was compared to simple, single‐term keyword searches.
Results
Almost 60% of quality criteria for the overall literature search strategy used in 182 systematic reviews were not respected. Over 30% of search strategies relied on a single keyword to identify the neurological condition. The sensitivities of our complex hedges amongst 10 311 articles were between 83% and 95%, significantly higher than the simple keyword searches (as low as 48%). The specificities were greater than 97%.
Conclusions
There is great room for improvement in the search strategies used in systematic reviews of neurological conditions. Complex hedges were developed and validated to improve the accuracy of such searches. It is expected that this will lead to higher quality systematic reviews and meta‐analyses.
Summary
Candida albicans biofilms are composed of highly adherent and densely arranged cells with properties distinct from those of free‐floating (planktonic) cells. These biofilms are a significant ...medical problem because they commonly form on implanted medical devices, are drug resistant and are difficult to remove. C. albicans biofilms are not static structures; rather they are dynamic and develop over time. Here we characterize gene expression in biofilms during their development, and by comparing them to multiple planktonic reference states, we identify patterns of gene expression relevant to biofilm formation. In particular, we document time‐dependent changes in genes involved in adhesion and metabolism, both of which are at the core of biofilm development. Additionally, we identify three new regulators of biofilm formation, Flo8, Gal4, and Rfx2, which play distinct roles during biofilm development over time. Flo8 is required for biofilm formation at all time points, and Gal4 and Rfx2 are needed for proper biofilm formation at intermediate time points.
Candida albicans biofilms are composed of highly adherent and densely arranged cells with properties distinct from those of free‐floating (planktonic) cells. These biofilms are not static structures; rather they are dynamic and develop over time. Here we characterize gene expression in biofilms during their development, and identify patterns of gene expression relevant to biofilm formation. We also identify three new regulators of biofilm formation, Flo8, Gal4, and Rfx2, which play distinct roles during biofilm development over time.
Prior studies on e-learning service quality were conducted mainly in developed countries; however, little effort has been made in emerging countries. This study examines the relationships among ...e-learning service quality attributes, overall e-learning service quality, e-learning student satisfaction, and e-learning student loyalty in the context of Vietnam, an emerging country. Survey data collected from 1232 college students were analyzed by means of exploratory factor analysis, confirmatory factor analysis, and structural equation modeling using SPSS 25 and SmartPLS 3.0. The results indicated that e-learning service quality was a second-order construct comprising of three factors, namely, e-learning system quality, e-learning instructor and course materials quality, and e-learning administrative and support service quality. The e-learning system quality was the most important dimension of overall e-learning service quality, followed by e-learning instructor and course materials quality, and e-learning administrative and support service quality. In addition, the overall e-learning service quality was positively related to e-learning student satisfaction, which in turn positively influences e-learning student loyalty. Also, overall e-learning service quality has a direct effect on e-learning student loyalty. Implications for colleges and universities are discussed.
Accurate crop yield forecasting is essential in the food industry's decision-making process, where vegetation condition index (VCI) and thermal condition index (TCI) coupled with machine learning ...(ML) algorithms play crucial roles. The drawback, however, is that a one-fits-all prediction model is often employed over an entire region without considering subregional VCI and TCI's spatial variability resulting from environmental and climatic factors. Furthermore, when using nonlinear ML, redundant VCI/TCI data present additional challenges that adversely affect the models' output. This study proposes a framework that (i) employs higher-order spatial independent component analysis (sICA), and (ii), exploits a combination of the principal component analysis (PCA) and ML (i.e., PCA-ML combination) to deal with the two challenges in order to enhance crop yield prediction accuracy. The proposed framework consolidates common VCI/TCI spatial variability into their respective subregions, using Vietnam as an example. Compared to the one-fits-all approach, subregional rice yield forecasting models over Vietnam improved by an average level of 20% up to 60%. PCA-ML combination outperformed ML-only by an average of 18.5% up to 45%. The framework generates rice yield predictions 1 to 2 months ahead of the harvest with an average of 5% error, displaying its reliability.
Vietnam, one of the three leading rice producers globally, has recently seen an increased threat to its rice production emanating from climate extremes (floods and droughts). Understanding ...spatio-temporal variability in precipitation and soil moisture is essential for policy formulations to adapt and cope with the impacts of climate extremes on rice production in Vietnam. Adopting a higher-order statistical method of independent component analysis (ICA), this study explores the spatio-temporal variability in the Climate Hazards Group InfraRed Precipitation Station's (CHIRPS) precipitation and the Global Land Data Assimilation System's (GLDAS) soil moisture products. The results indicate an agreement between monthly CHIRPS precipitation and monthly GLDAS soil moisture with the wetter period over the southern and South Central Coast areas that is latter than that over the northern and North Central Coast areas. However, the spatial patterns of annual mean precipitation and soil moisture disagree, likely due to factors other than precipitation affecting the amount of moisture in the soil layers, e.g., temperature, irrigation, and drainage systems, which are inconsistent between areas. The CHIRPS Standardized Precipitation Index (SPI) is useful in capturing climate extremes, and the GLDAS Standardized Soil Moisture Index (SSI) is useful in identifying the influences of climate extremes on rice production in Vietnam. During the 2016-2018 period, there existed a reduction in the residual rice yield that was consistent with a decrease in soil moisture during the same time period.
We sought to assess the relation of dietary trans fatty acid (dTFA) consumption to word-memory.
We analyzed cross-sectional data from the 1999-2005 UCSD Statin Study. Participants were 1018 adult men ...and non-procreative women age ≥20 without diagnosed diabetes, CVD, or extreme LDL-cholesterol. Primary analyses focused on men, as only men (N = 694) were effectively represented in younger adult ages. "Recurrent words" assessed word memory. dTFA (grams/day) estimates were calculated from the Fred Hutchinson Food Frequency Questionnaire. Regression, stratified at age 45, assessed the relation between memory and dTFA in various adjustment models. Major findings were replicated in the full sample (including women). Potential mediators were examined.
An age-by-dTFA interaction was significant. dTFA adversely predicted memory in younger adults (only), robust to adjustment model. Each gram/day dTFA was associated with an estimated 0.76 fewer words recalled (full model) (SE = 0.27, 95%CI = 0.22,1.3, P = 0.006). Adjustment for systolic blood pressure, waist circumference and BMI (but not lipid or glycemic variables) attenuated the relationship, consistent with mediation by factors involving, relating to, or concurrently influencing, these factors.
Greater dTFA was significantly associated with worse word recall in younger adults. Prooxidant and energetic detriments of dTFA and triangulation with other evidence offer prospects for causality.
Temperature is the most important factor to consider while constructing mass concrete. The resultant temperature is the result of cement hydration and other factors, resulting in the production of ...thermal cracks at an early age. As a result, the prediction of temperature fields in massive concrete structures has been a significant challenge. A temperature nomogram is created in this study by using numerical methods to quickly determine the maximum temperature in concrete structures with various characteristics, such as cement content and the initial temperature of concrete mixtures. The obtained monogram can be used to predict the maximum temperature in mass concrete structures in order to prevent thermal cracks during construction and thereafter.
Blockade of the programmed cell death protein/ligand 1 (PD-1/PD-L1) pathway with monoclonal antibodies (mAb) is now commonly used for cancer immunotherapy and has therapeutic potential in chronic ...viral infections including HIV-1. PD-1/PD-L1 blockade could augment HIV-1-specific immune responses and reverse HIV-1 latency, but the latter effect has not been clearly shown. We tested the ability of the human anti-PD-L1 mAb BMS-936559 and the human anti-PD-1 mAb nivolumab to increase HIV-1 virion production ex vivo from different peripheral blood mononuclear cell populations obtained from donors on suppressive antiretroviral therapy (ART). Fresh peripheral blood mononuclear cells (PBMC), CD8-depleted PBMC, total CD4+ T cells, and resting CD4+ T cells were purified from whole blood of HIV-1-infected donors and cultured in varying concentrations of BMS-936559 (20, 5, or 1.25μg/mL) or nivolumab (5 or 1.25μg/mL), with or without anti-CD3/CD28 stimulatory antibodies. Culture supernatants were assayed for virion HIV-1 RNA by qRT-PCR. Ex vivo exposure to BMS-936559 or nivolumab, with or without anti-CD3/CD28 stimulation, did not consistently increase HIV-1 virion production from blood mononuclear cell populations. Modest (2-fold) increases in virus production were observed in a subset of donors and in some cell types but were not reproducible in longitudinal samples. Cell surface expression of PD-1 and PD-L1 were not associated with changes in virus production. Ex vivo blockade of the PD-1 axis alone has limited effects on HIV-1 latency.
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