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At low Reynolds numbers, the flow through a pipe with a sudden expansion is characterized by the localized occurrence of flow instabilities, with the formation of a so-called turbulence puff. In the literature, physical experiments typically predict earlier occurrence of turbulence than computational fluid dynamics simulations. However, the behaviour of ‘natural’ transition to turbulence without perturbations, and the dependence of transition to turbulence on perturbations, are not yet fully understood, particularly for the simulations. The purpose of the present study is therefore to investigate this flow, including possible sources of perturbation in numerical simulations, and to evaluate their effect on transition to turbulence. Through the exploration of different flow rates, numerical settings and inlet perturbation amplitudes, and by evaluating coarse and refined simulations, insights into low-Reynolds-number transitional turbulent flows are obtained. The turbulence kinetic energy budget of the turbulence puff or slug characteristic of this flow is also evaluated. In conclusion, even when perturbations are not intentionally added, there can still be significant sources of numerical perturbation and error that trigger turbulence in simulations, but perturbations will need to be added in refined simulations in order to produce turbulence. Finally, the results agree with the notion that there may not be a scenario where the flow transitions naturally to turbulence without any perturbation.
In this paper, we expolore Multi-Agent Reinforcement Learning (MARL) methods for unmanned aerial vehicle (UAV) cluster. Considering that the current UAV cluster is still in the program control stage, the fully autonomous and intelligent cooperative combat has not been realised. In order to realise the autonomous planning of the UAV cluster according to the changing environment and cooperate with each other to complete the combat goal, we propose a new MARL framework. It adopts the policy of centralised training with decentralised execution, and uses Actor-Critic network to select the execution action and then to make the corresponding evaluation. The new algorithm makes three key improvements on the basis of Multi-Agent Deep Deterministic Policy Gradient (MADDPG) algorithm. The first is to improve learning framework; it makes the calculated Q value more accurate. The second is to add collision avoidance setting, which can increase the operational safety factor. And the third is to adjust reward mechanism; it can effectively improve the cluster’s cooperative ability. Then the improved MADDPG algorithm is tested by performing two conventional combat missions. The simulation results show that the learning efficiency is obviously improved, and the operational safety factor is further increased compared with the previous algorithm.
Background: In Canada, it’s unknown if the prevalence of stroke survivorship differs in the population with active cancer compared to those without cancer. Methods: We analyzed the 2015-2016 iteration of the Canadian Community Health Survey. The prevalence of stroke survivorship was compared across risk factors using descriptive statistics. A multivariable logistic regression model was used to assess the association between cancer and prevalence of stroke survivorship. Covariates were assessed for effect modification and confounding using the maximum likelihood estimation method. Results: We analyzed 89,285 subjects. The prevalence of cancer and the prevalence of suffering from the effects of a stroke were 2.09% and 1.56%, respectively. Cancer was significantly associated with an increased prevalence of stroke survivorship with an odds ratio (OR) of 1.56 (95%CI: 1.24 – 1.98) after adjusting for age, sex, smoking status, education, household income, dyslipidemia, hypertension, diabetes. The association was stronger in younger age groups: the youngest age group (18 – 49 years) had the highest OR (6.49, 95%CI:2.01 – 20.94) for suffering from the effects of a stroke in association with the presence of cancer. Conclusions: In Canada, the presence of active cancer increases the odds of suffering from the effects of a stroke, particularly in the youngest age group.
Background: This is a population-based retrospective study of neurological and cardiac complications of COVID-19 among Ontario visible minorities: Chinese and South Asian Canadians Methods: From January 1, 2020 to September 30, 2020, using the last name algorithm, rates and types of cardiac and neurological complication of these two cohorts along with the general population in Ontario with COVID-19 were analysed by Institue of Clinical Evaluative Sciences. Results: Preliminary results show that Chinese-Canadians (N= 1,186) with COVID-19 are older with a mean age of 50.74 years old compared to general population (N= 42,547) of 47.57 years old (P< .001), while South Asians (N= 3,459) have a younger mean age of 42.08 years old (P< .001). Total cardiac and neurological complication rates, hospitalization rates and ICU admission rates are all higher for Chinese-Canadians while they are lower in South Asians and all achieving statistical significance (P < .001). Overall mortality rate is significantly higher for Chinese-Canadians at 8.1% vs 5.0% general population (P < .001). Conclusions: Chinese-Canadians with COVID-19 in Ontario were much older and have higher cardiac and neurological complication rates and overall mortality rate than the general population. These data have significant implications for proper prevention and appropriate management for these vulnerble elderly Chinese-Canadians.
Three-scalar subgrid-scale (SGS) mixing in turbulent coaxial jets is investigated experimentally. The flow consists of a centre jet, an annulus and a co-flow. The SGS mixing process and its dependence on the velocity and length scale ratios of the annulus flow to the centre jet are investigated. For small SGS scalar variance the scalars are well mixed and the initial three-scalar mixing configuration is lost. For large SGS variance, the scalars are highly segregated with a bimodal scalar filtered joint density function (f.j.d.f.) at a range of radial locations. Two competing factors, the SGS variance and the scalar length scale, play an important role for the bimodal f.j.d.f. For the higher velocity ratio cases, the peak value of the SGS variance is higher, thereby resulting in stronger bimodality. For the lower velocity ratio cases, the wider mean SGS variance profiles and the smaller scalar length scale cause bimodal f.j.d.f.s over a wider range of physical locations. The scalar dissipation rate structures have similarities to those of mixture fraction and temperature in turbulent non-premixed/partially premixed flames. The observed SGS mixing characteristics present a challenging test for SGS mixing models as well as provides an understanding of the physics for developing improved models. The results also provide a basis for investigating multiscalar SGS mixing in turbulent reactive flows.
Although rare, coronary artery anomalies can have significant clinical implications. Total anomalous origin of the coronary arteries from the pulmonary artery (TCAPA) represents a rare subtype of coronary artery anomaly for which little is known. The aim of this review was to characterise the presentation, utilised diagnostic modalities, associated cardiac lesions, and treatment strategies in patients with TCAPA.
A systematic review was performed for cases of TCAPA using PubMed, Embase, and Web of Science. Keywords searched included “total anomalous origin of the coronary arteries from the pulmonary artery,” “single ostium anomalous coronary artery from the pulmonary artery,” and “anomalous origin of both coronary arteries from the pulmonary artery.”
Fifty-seven cases of TCAPA were identified in 50 manuscripts. Fifty-eight per cent of patients were male and the median age at presentation was 10 days (mean 1.71 ± 6.6 years, range 0 days–39 years). Most patients were symptomatic at the time of presentation; cyanosis (n = 22) and respiratory distress (n = 14) were the most common symptoms. Cases were most commonly diagnosed at autopsy (n = 26, 45.6%), but operative intervention was pursued in 22 cases (45.6%); aortic re-implantation (n = 14) and a Takeuchi-type repair (n = 7) were the most common routes of repair.
The clinical presentation of patients with TCAPA was found to be variable, likely related to the presence of associated cardiac lesions. TCAPA should be considered in patients with suspected anomalous origin of the left coronary artery from the pulmonary artery for the serious consequences that can occur if not promptly corrected.
The presence of excessive mirror overflow in children with Attention Deficit/Hyperactivity Disorder (ADHD) is discussed in numerous published reports. These reports, however, include a limited age range in their samples. The objective of this study is to examine the effects of diagnosis and sex on mirror overflow and standard deviation (SD) of tap time in children with and without ADHD across a larger age range (5–12 years) of children.
One-hundred and forty-eight children with ADHD and 112 age- and sex-matched typically developing (TD) children completed a finger sequencing task. Mirror overflow, SD of tap time, and mean tap time were measured using finger twitch transducers.
Results reveal a significant diagnostic effect on mirror overflow such that boys and girls with ADHD demonstrate increased overflow compared to same-sex TD children. Boys with ADHD demonstrated more variable tap times compared to TD boys; no diagnostic effect was observed in the girls.
Boys with ADHD exhibit anomalous motor variability; girls with ADHD show similar levels of variability as TD girls. Boys and girls with ADHD exhibit similar levels of excessive mirror overflow. This lack of sex differences on mirror overflow is distinct from reports finding sex effects on overflow and could result from an examination of a broader age range than is included in prior reports. Adolescent data would provide a greater understanding of the trajectory of anomalous mirror overflow across development. Examination of functional and structural connectivity would expand the current understanding of the neurobiological foundation of motor overflow.
Archaeological research demonstrates that an agropastoral economy was established in Tibet during the second millennium BC, aided by the cultivation of barley introduced from South-western Asia. The exact cultural contexts of the emergence and development of agropastoralism in Tibet, however, remain obscure. Recent excavations at the site of Bangga provide new evidence for settled agropastoralism in central Tibet, demonstrating a material divergence from earlier archaeological cultures, possibly corresponding to the intensification of agropastoralism in the first millennium BC. The authors’ results depict a more dynamic system of subsistence in the first millennium BC, as the populations moved readily between distinct economic modes and combined them in a variety of innovative ways.
Dry wind-tunnel (DWT) flutter test systems model the unsteady distributed aerodynamic force using various electromagnetic exciters. They can be used to test the aeroelastic and aeroservoelastic stability of smart aircraft or high-speed flight vehicles. A new parameterised modelling method at the full system level based on the generalised force equivalence for DWT flutter systems is proposed herein. The full system model includes the structural dynamic model, electromechanical coupling model and fast aerodynamic computation model. An optimisation search method is applied to determine the best locations for measurement and excitation by introducing Fisher’s information matrix. The feasibility and accuracy of the proposed system-level numerical DWT modelling method have been validated for a plate aeroelastic model with four exciters/transducers. The effects of key parameters including the number of exciters, the control time delay, the noise interference and the electrical parameters of the electromagnetic exciter model have also been investigated. The numerical and experimental results indicate that the proposed modelling method achieves good accuracy (with deviations of less than 1.5% from simulations and 4.5% from experimental test results for the flutter speed) and robust performance even in uncertain environments with a 10% noise level.
The hyper-function of the striatal dopamine system has been suggested to underlie key pathophysiological mechanisms in schizophrenia. Moreover, patients have been observed to present a significant elevation of dopamine receptor availability compared to healthy controls. Although it is difficult to measure dopamine levels directly in humans, neurochemical imaging techniques such as single-photon emission computed tomography (SPECT) provide indirect indices of in vivo dopamine synthesis and release, and putative synaptic levels.
We focused on the role of dopamine postsynaptic regulation using [123I] iodobenzamide (IBZM) SPECT. We compared D2/3 receptor availability between 53 healthy controls and 21 medication-naive patients with recent-onset schizophrenia.
The mean specific striatal binding showed no significant difference between patients and controls (estimated difference = 0.001; 95% CI −0.11 to 0.11; F = 0.00, df = 1, 69; p = 0.99). There was a highly significant effect of age whereby IBZM binding declined with advancing age [estimated change per decade of age = −0.01(binding ratio); 95% CI −0.01 to −0.004; F = 11.5, df = 1, 69; p = 0.001]. No significant correlations were found between the mean specific striatal binding and psychopathological or cognitive rating scores.
Medication-naïve patients with recent-onset schizophrenia have similar D2/3 receptor availability to healthy controls. We suggest that, rather than focusing exclusively on postsynaptic receptors, future treatments should target the presynaptic control of dopamine synthesis and release.
Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) led to a significant disease burden and disruptions in health systems. We describe the epidemiology and transmission characteristics of early coronavirus disease 2019 (COVID-19) cases in Bavaria, Germany. Cases were reverse transcription polymerase chain reaction (RT-PCR)-confirmed SARS-CoV-2 infections, reported from 20 January−19 March 2020. The incubation period was estimated using travel history and date of symptom onset. To estimate the serial interval, we identified pairs of index and secondary cases. By 19 March, 3546 cases were reported. A large proportion was exposed abroad (38%), causing further local transmission. Median incubation period of 256 cases with exposure abroad was 3.8 days (95%CI: 3.5–4.2). For 95% of infected individuals, symptom onset occurred within 10.3 days (95%CI: 9.1–11.8) after exposure. The median serial interval, using 53 pairs, was 3.5 days (95%CI: 3.0–4.2; mean: 3.9, s.d.: 2.2). Travellers returning to Germany had an important influence on the spread of SARS-CoV-2 infections in Bavaria in early 2020. Especially in times of low incidence, public health agencies should identify holiday destinations, and areas with ongoing local transmission, to monitor potential importation of SARS-CoV-2 infections. Travellers returning from areas with ongoing community transmission should be advised to quarantine to prevent re-introductions of COVID-19.
More than 50% patients with major depressive disorder (MDD) have severe functional impairment. The restoration of patient functioning is a critical therapeutic goal among patients with MDD. We conducted a systematic review and network meta-analysis to evaluate the efficacy of pharmacological treatments on self-rated functional outcomes using the Sheehan Disability Scale in adults with MDD in randomized clinical trials.
PubMed, EMBASE, PsycINFO, Cochrane Library, and ClinicalTrials.gov were searched from inception to December 10, 2019. Summary statistics are reported as weighted mean differences with 95% confidence intervals. Interventions were ranked using the surface under the cumulative ranking probabilities.
We included 42 randomized controlled trials (RCTs) (n = 18 998) evaluating the efficacy of 13 different pharmacological treatments on functional outcomes, as measured by the Sheehan Disability Scale (SDS). Duloxetine was the most effective pharmacological agent on functional outcomes, followed by (ranked by efficacy): paroxetine, levomilnacipran, venlafaxine, quetiapine, desvenlafaxine, agomelatine, escitalopram, amitriptyline, bupropion, sertraline, vortioxetine, and fluoxetine. Serotonin and norepinephrine reuptake inhibitors were more effective than other drug classes. Additionally, the comparison-adjusted funnel plot suggested the publication bias between small and large studies was relatively low.
Our results indicate that there may be differences across antidepressant agents and classes with respect to self-reported functional outcomes. Validation and replication of these findings in large-scale RCTs are warranted. Our research results will be clinically useful for guiding psychiatrists in treating patients with MDD and functional impairment. PROSPERO registration number CRD42018116663.
Benzodiazepine (BZD) prescription rates have increased over the past decade in the United States. Available literature indicates that sociodemographic factors may influence diagnostic patterns and/or prescription behaviour. Herein, the aim of this study is to determine whether the gender of the prescriber and/or patient influences BZD prescription.
Cross-sectional study using data from the Florida Medicaid Managed Medical Assistance Program from January 1, 2018 to December 31, 2018. Eligible recipients ages 18 to 64, inclusive, enrolled in the Florida Medicaid plan for at least 1 day, and were dually eligible. Recipients either had a serious mental illness (SMI), or non-SMI and anxiety.
Total 125 463 cases were identified (i.e., received BZD or non-BZD prescription). Main effect of patient and prescriber gender was significant F(1, 125 459) = 0.105, P = 0 .745, partial η2 < 0.001. Relative risk (RR) of male prescribers prescribing a BZD compared to female prescribers was 1.540, 95% confidence intervals (CI) [1.513, 1.567], whereas the RR of male patients being prescribed a BZD compared to female patients was 1.16, 95% CI [1.14, 1.18]. Main effects of patient and prescriber gender were statistically significant F(1, 125 459) = 188.232, P < 0.001, partial η2 = 0.001 and F(1, 125 459) = 349.704, P < 0.001, partial η2 = 0.013, respectively.
Male prescribers are more likely to prescribe BZDs, and male patients are more likely to receive BZDs. Further studies are required to characterize factors that influence this gender-by-gender interaction.
Both conflict resolution aid (CRA) and vertical situation display (VSD) systems may contribute to air traffic control (ATC) operations. However, their effectiveness still needs to be examined before being widely adopted in ATC facilities. This study aims to examine empirically the use of CRA and VSD as well as the systems’ interaction in ATC operations. It was found that CRA benefited conflict resolution performance by 13⋅7% and lowered workload by 46⋅4% compared with manually performing the task. The VSD could also reduce the air traffic controllers’ (ATCOs) workload and improve their situation awareness. Ultimately, when the first CRA failure occurred, the situation awareness supported by VSD offset the performance decrements by 30%. The findings from this study demonstrate that integrating VSD with CRA would benefit ATC operations, regardless of the CRA's imperfection.
There is compelling evidence for gradient effects of household income on school readiness. Potential mechanisms are described, yet the growth curve trajectory of maternal mental health in a child's early life has not been thoroughly investigated. We aimed to examine the relationships between household incomes, maternal mental health trajectories from antenatal to the postnatal period, and school readiness.
Prospective data from 505 mother–child dyads in a birth cohort in Singapore were used, including household income, repeated measures of maternal mental health from pregnancy to 2-years postpartum, and a range of child behavioural, socio-emotional and cognitive outcomes from 2 to 6 years of age. Antenatal mental health and its trajectory were tested as mediators in the latent growth curve models.
Household income was a robust predictor of antenatal maternal mental health and all child outcomes. Between children from the bottom and top household income quartiles, four dimensions of school readiness skills differed by a range of 0.52 (95% Cl: 0.23, 0.67) to 1.21 s.d. (95% CI: 1.02, 1.40). Thirty-eight percent of pregnant mothers in this cohort were found to have perinatal depressive and anxiety symptoms in the subclinical and clinical ranges. Poorer school readiness skills were found in children of these mothers when compared to those of mothers with little or no symptoms. After adjustment of unmeasured confounding on the indirect effect, antenatal maternal mental health provided a robust mediating path between household income and multiple school readiness outcomes (χ2 126.05, df 63, p < 0.001; RMSEA = 0.031, CFI = 0.980, SRMR = 0.034).
Pregnant mothers with mental health symptoms, particularly those from economically-challenged households, are potential targets for intervention to level the playing field of their children.
Mental health (MH) service users have increased prevalence of chronic physical conditions such as cardio-respiratory diseases and diabetes. Potentially Preventable Hospitalisations (PPH) for physical health conditions are an indicator of health service access, integration and effectiveness, and are elevated in long term studies of people with MH conditions. We aimed to examine whether PPH rates were elevated in MH service users over a 12-month follow-up period more suitable for routine health indicator reporting. We also examined whether MH service users had increased PPH rates at a younger age, potentially reflecting the younger onset of chronic physical conditions.
A population-wide data linkage in New South Wales (NSW), Australia, population 7.8 million. PPH rates in 178 009 people using community MH services in 2016–2017 were compared to population rates. Primary outcomes were crude and age- and disadvantage-standardised annual PPH episode rate (episodes per 100 000 population), PPH day rate (hospital days per 100 000) and adjusted incidence rate ratios (AIRR).
MH service users had higher rates of PPH admission (AIRR 3.6, 95% CI 3.5–3.6) and a larger number of hospital days (AIRR 5.2, 95% CI 5.2–5.3) than other NSW residents due to increased likelihood of admission, more admissions per person and longer length of stay. Increases were greatest for vaccine-preventable conditions (AIRR 4.7, 95% CI 4.5–5.0), and chronic conditions (AIRR 3.7, 95% CI 3.6–3.7). The highest number of admissions and relative risks were for respiratory and metabolic conditions, including chronic obstructive airways disease (AIRR 5.8, 95% CI 5.5–6.0) and diabetic complications (AIRR 5.4, 95% CI 5.1–5.8). One-quarter of excess potentially preventable bed days in MH service users were due to vaccine-related conditions, including vaccine-preventable respiratory illness. Age-related increases in risk occurred earlier in MH service users, particularly for chronic and vaccine-preventable conditions. PPH rates in MH service users aged 20–29 were similar to population rates of people aged 60 and over. These substantial differences were not explained by socio-economic disadvantage.
PPHs for physical health conditions are substantially increased in people with MH conditions. Short term (12-month) PPH rates may be a useful lead indicator of increased physical morbidity and less accessible, integrated or effective health care. High hospitalisation rates for vaccine-preventable respiratory infections and hepatitis underline the importance of vaccination in MH service users and suggests potential benefits of prioritising this group for COVID-19 vaccination.
An acute gastroenteritis (AGE) outbreak caused by a norovirus occurred at a hospital in Shanghai, China, was studied for molecular epidemiology, host susceptibility and serological roles. Rectal and environmental swabs, paired serum samples and saliva specimens were collected. Pathogens were detected by real-time polymerase chain reaction and DNA sequencing. Histo-blood group antigens (HBGA) phenotypes of saliva samples and their binding to norovirus protruding proteins were determined by enzyme-linked immunosorbent assay. The HBGA-binding interfaces and the surrounding region were analysed by the MegAlign program of DNAstar 7.1. Twenty-seven individuals in two care units were attacked with AGE at attack rates of 9.02 and 11.68%. Eighteen (78.2%) symptomatic and five (38.4%) asymptomatic individuals were GII.6/b norovirus positive. Saliva-based HBGA phenotyping showed that all symptomatic and asymptomatic cases belonged to A, B, AB or O secretors. Only four (16.7%) out of the 24 tested serum samples showed low blockade activity against HBGA-norovirus binding at the acute phase, whereas 11 (45.8%) samples at the convalescence stage showed seroconversion of such blockade. Specific blockade antibody in the population played an essential role in this norovirus epidemic. A wide HBGA-binding spectrum of GII.6 supports a need for continuous health attention and surveillance in different settings.
We present here the first study on the stability of plane Poiseuille flow when the fluid is stratified in density perpendicularly to the plane of horizontal shear. Using laboratory experiments, linear stability analyses and direct numerical simulations, we describe the appearance of an instability that results from a resonance of internal gravity waves and Tollmien–Schlichting waves carried by the flow. This instability takes the form of long meanders confined in thin horizontal layers stacked along the vertical axis.