| 171. |
- Qu, L. X., et al.
(författare)
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Quantitative numerical analysis of flow past a circular cylinder at Reynolds number between 50 and 200
- 2013
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Ingår i: Journal of Fluids and Structures. - : Elsevier BV. - 1095-8622 .- 0889-9746. ; 39, s. 347-370
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Tidskriftsartikel (refereegranskat)abstract
- Results of numerical simulations are presented for flow past a stationary circular cylinder at low Reynolds numbers (Re=50-200). The simulations were carried out using a finite-volume code employing a fractional step method with second-order accuracy in both space and time. A sensitivity study on numerical parameters concerning the domain size, grid independence and time step resolution was carried out in detail for Re=100. Global time-averaged results on force coefficients, non-dimensional velocities and pressures, including their corresponding r.m.s. values, as well as various quantities related to the separation and vortex shedding characteristics are presented. A non-monotonous streamwise velocity recovery in the intermediate wake is observed for Re > 50, a phenomenon that has been grossly overlooked in the past. There are two plateaus along the wake centerline, in particular for Re=200. The first, which is the most distinct, ranges from about x=9 to x=16 at a wake deficit velocity of 0.38, x being counted in diameters behind the cylinder axis; the second one appears from x=25 to x=28 at a wake deficit velocity of 0.54. This phenomenon seems to be related to an associated change-over in the orientation of the von Karman vortices and the merging trends, especially for Re=200 beyond x=25, as observed from instantaneous vorticity fields. Three-dimensional simulations using spanwise lengths of 10 and 12 (diameters) were carried out at Re=200. After a long initial phase with regular three-dimensional mode A flow features increasing very slowly in amplitude, the flow went into a state with distinct pulsating forces acting on the cylinder, the pulsations being seemingly randomly localized across the cylinder span. In this second, much more chaotic, flow state, the time-averaged results were in agreement with previous experiments and with parts of previous numerical studies.
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| 172. |
- Qu, X. B., et al.
(författare)
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Accelerated NMR Spectroscopy with Low-Rank Reconstruction
- 2015
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Ingår i: Angewandte Chemie-International Edition. - : Wiley. - 1433-7851. ; 54:3, s. 852-854
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Tidskriftsartikel (refereegranskat)abstract
- Accelerated multi-dimensional NMR spectroscopy is a prerequisite for high-throughput applications, studying short-lived molecular systems and monitoring chemical reactions in real time. Non-uniform sampling is a common approach to reduce the measurement time. Here, a new method for high-quality spectra reconstruction from non-uniformly sampled data is introduced, which is based on recent developments in the field of signal processing theory and uses the so far unexploited general property of the NMR signal, its low rank. Using experimental and simulated data, we demonstrate that the low-rank reconstruction is a viable alternative to the current state-of-the-art technique compressed sensing. In particular, the low-rank approach is good in preserving of low-intensity broad peaks, and thus increases the effective sensitivity in the reconstructed spectra.
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| 173. |
- Qu, Xiaobo, 1983, et al.
(författare)
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Jointly dampening traffic oscillations and improving energy consumption with electric, connected and automated vehicles: A reinforcement learning based approach
- 2020
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Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 257
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Tidskriftsartikel (refereegranskat)abstract
- It has been well recognized that human driver's limits, heterogeneity, and selfishness substantially compromise the performance of our urban transport systems. In recent years, in order to deal with these deficiencies, our urban transport systems have been transforming with the blossom of key vehicle technology innovations, most notably, connected and automated vehicles. In this paper, we develop a car following model for electric, connected and automated vehicles based on reinforcement learning with the aim to dampen traffic oscillations (stop-and-go traffic waves) caused by human drivers and improve electric energy consumption. Compared to classical modelling approaches, the proposed reinforcement learning based model significantly reduces the modelling constraints and has the capability of self-learning and self-correction. Experiment results demonstrate that the proposed model is able to improve travel efficiency by reducing the negative impact of traffic oscillations, and it can also reduce the average electric energy consumption.
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| 174. |
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| 175. |
- Su, Yu-Ru, et al.
(författare)
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Validation of a genetic-enhanced risk prediction model for colorectal cancer in a large community-based cohort
- 2023
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Ingår i: Cancer Epidemiology, Biomarkers and Prevention. - : American association for cancer research. - 1055-9965 .- 1538-7755. ; 32:3, s. 353-362
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Polygenic risk scores (PRS) which summarize individuals' genetic risk profile may enhance targeted colorectal cancer screening. A critical step towards clinical implementation is rigorous external validations in large community-based cohorts. This study externally validated a PRS-enhanced colorectal cancer risk model comprising 140 known colorectal cancer loci to provide a comprehensive assessment on prediction performance.METHODS: The model was developed using 20,338 individuals and externally validated in a community-based cohort (n = 85,221). We validated predicted 5-year absolute colorectal cancer risk, including calibration using expected-to-observed case ratios (E/O) and calibration plots, and discriminatory accuracy using time-dependent AUC. The PRS-related improvement in AUC, sensitivity and specificity were assessed in individuals of age 45 to 74 years (screening-eligible age group) and 40 to 49 years with no endoscopy history (younger-age group).RESULTS: In European-ancestral individuals, the predicted 5-year risk calibrated well [E/O = 1.01; 95% confidence interval (CI), 0.91-1.13] and had high discriminatory accuracy (AUC = 0.73; 95% CI, 0.71-0.76). Adding the PRS to a model with age, sex, family and endoscopy history improved the 5-year AUC by 0.06 (P < 0.001) and 0.14 (P = 0.05) in the screening-eligible age and younger-age groups, respectively. Using a risk-threshold of 5-year SEER colorectal cancer incidence rate at age 50 years, adding the PRS had a similar sensitivity but improved the specificity by 11% (P < 0.001) in the screening-eligible age group. In the younger-age group it improved the sensitivity by 27% (P = 0.04) with similar specificity.CONCLUSIONS: The proposed PRS-enhanced model provides a well-calibrated 5-year colorectal cancer risk prediction and improves discriminatory accuracy in the external cohort.IMPACT: The proposed model has potential utility in risk-stratified colorectal cancer prevention.
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| 176. |
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| 177. |
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| 178. |
- Wan, Bo, et al.
(författare)
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Re-Os molybdenite age of the Cu-Mo skarn ore deposit at Suoerkuduke in East Junggar, NW China and its geological significance
- 2014
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Ingår i: Ore Geology Reviews. - : Elsevier BV. - 0169-1368 .- 1872-7360. ; 56, s. 541-548
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Forskningsöversikt (refereegranskat)abstract
- The Suoerkuduke Cu-Mo ore is a medium-sized skarn deposit in the East Junggar orogen of the southern Altaids, Xinjiang, Northwest China. We measured Re-Os isotopes of a molybdenite veinlet from the main ore body, of which eight yielded model ages ranging from 303 +/- 5 to 317 +/- 5 Ma with a well-constrained Re-187-Os-187 isochron age of 305 +/- 7 Ma, a MSWD of 4.9 and a weighted average model age of 310 +/- 4 Ma with a MSWD of 4.2. The Re-187-Os-187 isochron age is consistent with the weighted mean model age, within error, and indicates that the time of Cu-Mo mineralization was at c. 310 Ma in the late Carboniferous. This new age is close to the youngest porphyry-related Cu-Mo metallogenic epoch (c. 311 Ma) in the East Junggar region, and is not, as previously suggested, in the Permian. Considering the implications of this new age, we propose that the Suoerkuduke deposit was part of a large-scale porphyry-skarn system, which formed by the interaction between far-traveled hydrothermal fluids and the calcium-rich volcanic wall rocks.
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| 179. |
- Wang, JR, et al.
(författare)
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Cardiovascular-related deaths at the beginning of the COVID-19 outbreak: a prospective analysis based on the UK Biobank
- 2021
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 11:6, s. e046931-
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Tidskriftsartikel (refereegranskat)abstract
- To assess the impact of the COVID-19 outbreak on cardiovascular disease (CVD) related mortality and hospitalisation.DesignCommunity-based prospective cohort study.SettingThe UK Biobank.Participants421 372 UK Biobank participants who were registered in England and alive as of 1 January 2020.Primary and secondary outcome measuresThe primary outcome of interest was CVD-related death, which was defined as death with CVD as a cause in the death register. We retrieved information on hospitalisations with CVD as the primary diagnosis from the UK Biobank hospital inpatient data. The study period was 1 January 2020 to June 30 2020, and we used the same calendar period of the three preceding years as the reference period. In order to control for seasonal variations and ageing of the study population, standardised mortality/incidence ratios (SMRs/SIRs) with 95% CIs were used to estimate the relative risk of CVD outcomes during the study period, compared with the reference period.ResultsWe observed a distinct increase in CVD-related deaths in March and April 2020, compared with the corresponding months of the three preceding years. The observed number of CVD-related deaths (n=218) was almost double in April, compared with the expected number (n=120) (SMR=1.82, 95% CI 1.58 to 2.07). In addition, we observed a significant decline in CVD-related hospitalisations from March onwards, with the lowest SIR observed in April (0.45, 95% CI 0.41 to 0.49).ConclusionsThere was a distinct increase in the number of CVD-related deaths in the UK Biobank population at the beginning of the COVID-19 outbreak. The shortage of medical resources for hospital care and stress reactions to the pandemic might have partially contributed to the excess CVD-related mortality, underscoring the need of sufficient healthcare resources and improved instructions to the public about seeking healthcare in a timely way.
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| 180. |
- Wang, Y, et al.
(författare)
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Trends in incident diagnoses and drug prescriptions for anxiety and depression during the COVID-19 pandemic: an 18-month follow-up study based on the UK Biobank
- 2023
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Ingår i: Translational psychiatry. - : Springer Science and Business Media LLC. - 2158-3188. ; 13:1, s. 12-
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Tidskriftsartikel (refereegranskat)abstract
- Serious concerns have been raised about the negative effects of the COVID-19 pandemic on population psychological well-being. However, limited data exist on the long-term effects of the pandemic on incident psychiatric morbidities among individuals with varying exposure to the pandemic. Leveraging prospective data from the community-based UK Biobank cohort, we included 308,400 participants free of diagnosis of anxiety or depression, as well as 213,757 participants free of anxiolytics or antidepressants prescriptions, to explore the trends in incident diagnoses and drug prescriptions for anxiety and depression from 16 March 2020 to 31 August 2021, compared to the pre-pandemic period (i.e., 1 January 2017 to 31 December 2019) and across populations with different exposure statuses (i.e., not tested for COVID-19, tested negative and tested positive). The age- and sex-standardized incidence ratios (SIRs) were calculated by month which indicated an increase in incident diagnoses of anxiety or depression among individuals who were tested for COVID-19 (tested negative: SIR 3.05 [95% confidence interval 2.88–3.22]; tested positive: 2.03 [1.76–2.34]), especially during the first six months of the pandemic (i.e., March-September 2020). Similar increases were also observed for incident prescriptions of anxiolytics or antidepressants (tested negative: 1.56 [1.47–1.67]; tested positive: 1.41 [1.22–1.62]). In contrast, individuals not tested for COVID-19 had consistently lower incidence rates of both diagnoses of anxiety or depression (0.70 [0.67–0.72]) and prescriptions of respective psychotropic medications (0.70 [0.68–0.72]) during the pandemic period. These data suggest a distinct rise in health care needs for anxiety and depression among individuals tested for COVID-19, regardless of the test result, in contrast to a reduction in health care consumption for these disorders among individuals not tested for and, presumably, not directly exposed to the disease.
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