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The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) is highly contagious, and the coronavirus disease 2019 (COVID-19) pandemic caused by it has forced many countries to adopt ‘lockdown’ measures to prevent the spread of the epidemic through social isolation of citizens. Some countries proposed universal mask wearing as a protection measure of public health to strengthen national prevention efforts and to limit the wider spread of the epidemic. In order to reveal the epidemic prevention efficacy of masks, this paper systematically evaluates the experimental studies of various masks and filter materials, summarises the general characteristics of the filtration efficiency of isolation masks with particle size, and reveals the actual efficacy of masks by combining the volume distribution characteristics of human exhaled droplets with different particle sizes and the SARS-CoV-2 virus load of nasopharynx and throat swabs from patients. The existing measured data show that the filtration efficiency of all kinds of masks for large particles and extra-large droplets is close to 100%. From the perspective of filtering the total number of pathogens discharged in the environment and protecting vulnerable individuals from breathing live viruses, the mask has a higher protective effect. If considering the weighted average filtration efficiency with different particle sizes, the filtration efficiencies of the N95 mask and the ordinary mask are 99.4% and 98.5%, respectively. The mask can avoid releasing active viruses to the environment from the source of infection, thus maximising the protection of vulnerable individuals by reducing the probability of inhaling a virus. Therefore, if the whole society strictly implements the policy of publicly wearing masks, the risk of large-scale spread of the epidemic can be greatly reduced. Compared with the overall cost of social isolation, limited personal freedoms and forced suspension of economic activities, the inconvenience for citizens caused by wearing masks is perfectly acceptable.
Vertex-primitive self-complementary graphs were proved to be affine or in product action by Guralnick et al. [‘On orbital partitions and exceptionality of primitive permutation groups’, Trans. Amer. Math. Soc.356 (2004), 4857–4872]. The product action type is known in some sense. In this paper, we provide a generic construction for the affine case and several families of new self-complementary Cayley graphs are constructed.
The association between dietary Fe intake and diabetes risk remains inconsistent. We aimed to explore the association between dietary Fe intake and type 2 diabetes mellitus (T2DM) risk in middle-aged and older adults in urban China. This study used data from the Guangzhou Nutrition and Health Study, an on-going community-based prospective cohort study. Participants were recruited from 2008 to 2013 in Guangzhou community. A total of 2696 participants aged 40–75 years without T2DM at baseline were included in data analyses, with a median of 5·6 (interquartile range 4·1–5·9) years of follow-up. T2DM was identified by self-reported diagnosis, fasting glucose ≥ 7·0 mmol/l or glycosylated Hb ≥ 6·5 %. Cox proportional hazard models were used to estimate hazard ratios (HR) and 95 % CI. We ascertained 205 incident T2DM cases during 13 476 person-years. The adjusted HR for T2DM risk in the fourth quartile of haem Fe intake was 1·92 (95 % CI 1·07, 3·46; Ptrend = 0·010), compared with the first quartile intake. These significant associations were found in haem Fe intake from total meat (HR 2·74; 95 % CI 1·22, 6·15; Ptrend = 0·011) and haem Fe intake from red meat (HR 1·86; 95 % CI 1·01, 3·44; Ptrend = 0·034), but not haem Fe intake from processed meat, poultry or fish/shellfish. The association between dietary intake of total Fe or non-haem Fe with T2DM risk had no significance. Our findings suggested that higher dietary intake of haem Fe (especially from red meat), but not total Fe or non-haem Fe, was associated with greater T2DM risk in middle-aged and older adults.
To evaluate the epidemiological and clinical characteristics of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) infection among healthcare workers (HCWs) in Hubei Province, China.
Retrospective cohort study.
Hubei Provincial Center for Disease Control and Prevention.
The participants in this study are cases identified by epidemiological investigation in Hubei Province, as of February 27, 2020, and were followed until March 7, 2020. In total, 1,989 HCWs and 41,137 other occupational cases were included for analysis.
We used descriptive statistics to summarize patient characteristics.
Of 1,989 laboratory-confirmed HCWs, 297 (14.93%) had severe or critical cases, 73 (3.67%) had asymptomatic infections, and 18 died of coronavirus disease 2019 (COVID-19). The case fatality rate was 0.9%. The proportion of severe or critical cases decreased from the beginning to the end of the outbreak (from 21.29% to 3.52%), and the proportion of asymptomatic cases increased from 0.0% to 47.18%. Nearly half of HCWs with confirmed COVID-19 reported no known contact with COVID-19 patients (969, 48.72%). Fever and cough were the most common symptoms at disease onset in both HCWs and other occupational cases; however, HCWs had higher rates of fatigue (30.90% vs 25.02%; P < .001) and myalgia (19.15% vs 13.43%; P < .001). Additionally, compared with other occupational groups, HCWs were associated with a lower risk of death after adjustment for potential confounders (odd ratio [OR], 0.50; 95% confidence interval [CI], 0.30–0.79).
Compared with COVID-19 cases in other occupational groups, HCWs with COVID-19 have half the risk of death, although they have been shown to have higher rates of fatigue and myalgia.
To evaluate a large portfolio of variable annuity (VA) contracts, many insurance companies rely on Monte Carlo simulation, which is computationally intensive. To address this computational challenge, machine learning techniques have been adopted in recent years to estimate the fair market values (FMVs) of a large number of contracts. It is shown that bootstrapped aggregation (bagging), one of the most popular machine learning algorithms, performs well in valuing VA contracts using related attributes. In this article, we highlight the presence of prediction bias of bagging and use the bias-corrected (BC) bagging approach to reduce the bias and thus improve the predictive performance. Experimental results demonstrate the effectiveness of BC bagging as compared with bagging, boosting, and model points in terms of prediction accuracy.
The clinical characteristics of patients with COVID-19 were analysed to determine the factors influencing the prognosis and virus shedding time to facilitate early detection of disease progression. Logistic regression analysis was used to explore the relationships among prognosis, clinical characteristics and laboratory indexes. The predictive value of this model was assessed with receiver operating characteristic curve analysis, calibration and internal validation. The viral shedding duration was calculated using the Kaplan–Meier method, and the prognostic factors were analysed by univariate log-rank analysis and the Cox proportional hazards model. A retrospective study was carried out with patients with COVID-19 in Tianjin, China. A total of 185 patients were included, 27 (14.59%) of whom were severely ill at the time of discharge and three (1.6%) of whom died. Our findings demonstrate that patients with an advanced age, diabetes, a low PaO2/FiO2 value and delayed treatment should be carefully monitored for disease progression to reduce the incidence of severe disease. Hypoproteinaemia and the fever duration warrant special attention. Timely interventions in symptomatic patients and a time from symptom onset to treatment <4 days can shorten the duration of viral shedding.
Dolostones are widely developed in the middle Permian rocks of East Yunnan, China, mainly in the shoal-facies Maokou Formation. The previously reported dolostone formation mechanisms cannot explain the distribution and geochemical characteristics of these dolostones, in particular their strontium, magnesium and oxygen isotope signatures. To help predict the distribution of dolostone reservoirs and reduce the exploration risk and cost, this study proposes a new model of dolomitization: open thermal convection dolomitization. In this new dolomitization model, Mg2+ in dolomitizing fluids originates mostly from seawater, with a minor component coming from deep hydrothermal fluids. Elevated heat flux (in this case due to the nearby Emei mantle plume) causes spatial temperature variations in the fluid along the circulation flow pathways, resulting in fast and pervasive dolomitization of limestone. The proposed model not only explains the characteristics and distribution of dolostones in the study area but also serves as a reference for predicting the distribution of dolostones in other areas subjected to thermal convection.
In this paper, we solve exit problems for a one-sided Markov additive process (MAP) which is exponentially killed with a bivariate killing intensity
dependent on the present level of the process and the current state of the environment. Moreover, we analyze the respective resolvents. All identities are expressed in terms of new generalizations of classical scale matrices for MAPs. We also remark on a number of applications of the obtained identities to (controlled) insurance risk processes. In particular, we show that our results can be applied to the Omega model, where bankruptcy takes place at rate
when the surplus process becomes negative. Finally, we consider Markov-modulated Brownian motion (MMBM) as a special case and present analytical and numerical results for a particular choice of piecewise intensity function
In this process-based study, we introduced a collocation tool with a new interface and advanced search features and examined how a class of EFL college students interacted with it. To elicit their tool consultation behaviors, a vocabulary test with collocation questions was designed. The students’ use of the tool to answer the vocabulary questions was screen-recorded for further analysis, serving as the major data source. One-on-one interviews with selected students were then conducted to clarify issues related to the study and their experience in using the tool. The findings indicated that the pattern-based tool was efficient in helping students solve collocation problems. This paper concludes with some pedagogical implications and suggestions for further research.
Drawing from eleven rich case studies in Asia, this book is the first to explore how heritage is used as aid and diplomacy by various agencies to produce knowledge, power, values and geopolitics in the global heritage regime. It represents an interdisciplinary endeavour to feature a diversity of situations where cultural heritage is invoked or promoted to serve interests or visions that supposedly transcend local or national paradigms. This collection of articles thus not only considers processes of "UNESCO-ization" of heritage (or their equivalents when conducted by other international or national actors) by exploring the diplomatic and developmentalist politics of heritage-making at play and its transformational impact on societies. It also describes how local and outside states often collude with international mechanisms to further their interests at the expense of local communities and of citizens' rights.Heritage as Aid and Diplomacy in Asia explores the following questions: Under the current international heritage regime, what are the mechanisms of-and the manipulations that take place within-ideological, political and cultural transmissions? What is heritage diplomacy and how can we conceptualize it? How do the complicated history and colonial past of Asia constitute the current practices of heritage diplomacy and shape heritage discourse in Asia? How do international organizations, nation-states, NGOs, heritage brokers and experts contribute to the history of the global heritage discourse? How has the flow of global knowledge been transferred and transformed? And how does the global hierarchy of cultural values function?
In spite of a growing academic interest in the politics of heritage in Asia, few studies have directly questioned the role of international and transnational cooperation in heritage conservation. First, even though the literature has widely addressed the role of the United Nations Educational, Scientific and Cultural Organization (UNESCO) as a powerful disseminator of international standards of conservation (e.g., Askew 2010; Daly and Winter 2012; Labadi 2010, 2013a; Logan 2001), it has not yet tackled the impact of UNESCO's normative discourse on other cultural policy agents. Secondly, the social sciences have largely neglected other international structures such as the International Monetary Fund (IMF), the World Bank, the European Union, USAid, the Asian Development Bank and many others that have their own engagements in the conservation of heritage in Asia. These organizations often collaborate with UNESCO or participate in bilateral or multilateral initiatives by providing funding and “expertise” in the management of sites. The IMF, for instance, played an important role in the establishment of the International Coordinating Committee of the World Heritage Site (hereafter WHS) of Angkor under the aegis of UNESCO. Many of these initiatives are carried out by states’ cultural diplomacies in often well-thought-out strategies. Pioneer countries in cultural diplomacy include France, Italy and the Netherlands, but also India and Japan. Today, most Asian states are also engaging in cultural diplomacy. In the last two decades, China, South Korea, Thailand, Vietnam and Indonesia have considerably strengthened their investments in regional “heritage cooperation”. Some of them, like India or Japan, have a long history of cultural international intervention (Ray 2012). Thirdly, private “philanthropic” programmes like the Ford Foundation, the Agha Khan Foundation, the World Monuments Fund and the Getty Trust have long had a major impact on the management of heritage in Asia. They are now joined by newly established Asia-based foundations such as Korea's Samsung Foundation. Finally, new connections have recently been drawn between market-driven “development” schemes explicitly linking “culture” and “economic opportunities” as part of the global capitaldriven developmentalist discourse, as when WHS become mass tourism destinations incorporated in national economic development schemes (Labadi and Logan 2016).
Ketosis is a metabolic disease of dairy cows often characterized by high concentrations of ketone bodies and fatty acids, but low milk protein and milk production. The Janus kinase 2 (JAK2)-signal transducer and activator of transcription 5 (STAT5) and the mechanistic target of rapamycin (mTOR) signaling pathways are central for the regulation of milk protein synthesis. The effect of high levels of fatty acids on these pathways and β-casein synthesis are unknown in dairy cows with clinical ketosis. Mammary gland tissue and blood samples were collected from healthy (n = 15) and clinically-ketotic (n = 15) cows. In addition, bovine mammary epithelial cells (BMEC) were treated with fatty acids, methionine (Met) or prolactin (PRL), respectively. In vivo, the serum concentration of fatty acids was greater (P > 0.05) and the percentage of milk protein (P > 0.05) was lower in cows with clinical ketosis. The JAK2-STAT5 and mTOR signaling pathways were inhibited and the abundance of β-casein was lower in mammary tissue of cows with clinical ketosis (P > 0.05). In vitro, high levels of fatty acids inhibited the JAK2-STAT5 and mTOR signaling pathways (P > 0.05) and further decreased the β-casein synthesis (P > 0.05) in BMEC. Methionine or PRL treatment, as positive regulators, activated the JAK2-STAT5 and mTOR signaling pathways to increase the β-casein synthesis. Importantly, the high concentration of fatty acids attenuated the positive effect of Met or PRL on mTOR, JAK2-STAT5 pathways and the abundance of β-casein (P > 0.05). Overall, these data indicate that the high concentrations of fatty acids that reach the mammary cells during clinical ketosis inhibit mTOR and JAK2-STAT5 signaling pathways, and further suppress β-casein synthesis.
Amnestic mild cognitive impairment (aMCI) is characterized by delayed P300 latency and reduced grey matter (GM) volume, respectively. The relationship between the features in aMCI is unclear. This study was to investigate the relationship between the altered P300 latency and the GM volume in aMCI.
Thirty-four aMCI and 34 well-matched normal controls (NC) were studied using electroencephalogram during a visual oddball task and scanned with MRI. Both tests were finished in the same day.
As compared with the NC group, the aMCI group exhibited delayed P300 latency in parietal cortex and reduced GM volumes in bilateral temporal pole and left hippocampus/parahippocampal gyrus. A remarkable negative correlation was found between delayed P300 latency and reduced left hippocampal volume only in the aMCI group. Interestingly, the mediating analysis found P300 latency significantly mediated the association between right supramarginal gyrus volume and information processing speed indicated by Stroop Color and Word Test A scores.
The association between delayed P300 latency and reduced left hippocampal volume in aMCI subjects suggests that reduced left hippocampal volume may be the potential structural basis of delayed P300 latency.
Findings for the roles of dairy products, Ca and vitamin D on ovarian cancer risk remain controversial. We aimed to assess these associations by using an updated meta-analysis. Five electronic databases (e.g. PubMed and Embase) were searched from inception to 24 December 2019. Pooled relative risks (RR) with 95 % CI were calculated. A total of twenty-nine case–control or cohort studies were included. For comparisons of the highest v. lowest intakes, higher whole milk intake was associated with increased ovarian cancer risk (RR 1·35; 95 % CI 1·15, 1·59), whereas decreased risks were observed for higher intakes of low-fat milk (RR 0·84; 95 % CI 0·73, 0·96), dietary Ca (RR 0·71; 95 % CI 0·60, 0·84) and dietary vitamin D (RR 0·80; 95 % CI 0·67, 0·95). Additionally, for every 100 g/d increment, increased ovarian cancer risks were found for total dairy products (RR 1·03; 95 % CI 1·01, 1·04) and for whole milk (RR 1·07; 95 % CI 1·03, 1·11); however, decreased risks were found for 100 g/d increased intakes of low-fat milk (RR 0·95; 95 % CI 0·91, 0·99), cheese (RR 0·87; 95 % CI 0·76, 0·98), dietary Ca (RR 0·96; 95 % CI 0·95, 0·98), total Ca (RR 0·98; 95 % CI 0·97, 0·99), dietary vitamin D (RR 0·92; 95 % CI 0·87, 0·97) and increased levels of circulating vitamin D (RR 0·84; 95 % CI 0·72, 0·97). These results show that whole milk intake might contribute to a higher ovarian cancer risk, whereas low-fat milk, dietary Ca and dietary vitamin D might reduce the risk.
To summarize characteristics and commonalities of non-technical competency frameworks for health professionals in emergency and disaster.
An electronic literature search was conducted in PubMed, MEDLINE, ERIC, Scopus, Cochrane database, and Google Scholar to identify original English-language articles related to development, evaluation or application of the nontechnical competency frameworks. Reviewers assessed identified articles for exclusion/inclusion criteria and abstracted data on study design, framework characteristics, and reliability/validity evidence.
Of the 9627 abstracts screened, 65 frameworks were identiﬁed from 94 studies that were eligible for result extraction. Sixty (63.8%) studies concentrated on clinical settings. Common scenarios of the studies were acute critical events in hospitals (44;46.8%) and nonspecified disasters (39;41.5%). Most of the participants (76; 80.9%) were clinical practitioners, and participants in 36 (38.3%) studies were multispecialty. Thirty-three (50.8%) and 42 (64.6%) frameworks had not reported evidence on reliability and validity, respectively. Fourteen of the most commonly involved domains were identified from the frameworks.
Nontechnical competency frameworks applied to multidisciplinary emergency health professionals are heterogeneous in construct and application. A fundamental framework with standardized terminology for the articulation of competency should be developed and validated so as to be accepted and adapted universally by health professionals in all-hazard emergency environment.