Theoretical model and characteristics analysis of deflector-jet servo valve’s pilot stage

To analyze the deflector-jet servo valve’s internal flow characteristics, a theoretical model of the complicated flow distribution in the deflector plate is established based on the offset jet attachment theory. When the deflector plate offsets, jet attachment parameters are attained to figure out the jet’s bending and colliding process. On this basis, an analytical method of acquiring the pilot valve’s pressure gain is derived. According to an actual pilot stage’s structure, pressure gain calculations are carried out. Meanwhile, the pilot valve’s mesh model is established for numerical simulation in order to examine the accuracy of the theoretical model. Calculation and numerical simulation show that the final oil jet is not sensitive to the deflector plate’s movement, which directly reveals the pressure stabilizing effect of the V-shaped structure on the deflector plate. Moreover, the experiment on the pressure gain is accomplished and experiment results verify the accuracy of the analytical calculation

Constraints on millicharged dark matter and axion-like particles from timing of radio waves

We derive novel constraints on millicharged dark matter and ultralight axion-like particles using pulsar timing and fast radio burst observations. Millicharged dark matter affects the dispersion measure of the time of arrival of radio pulses in a way analogous to free electrons. Light pseudo-scalar dark matter, on the other hand, causes the polarization angle of radio signals to oscillate. We show that current and future data can set strong constraints in both cases. For dark matter particles of charge $\epsilon e$, these constraints are ${\epsilon}/{m_{\rm milli}} \lesssim 10^{-8}{\rm eV}^{-1}$, for masses $m_{\rm milli}\gtrsim 10^{-6}\,$eV. For axion-like particles, the analysis of signals from pulsars yields constraints in the axial coupling of the order of $g/m_a\lesssim 10^{-13} {\rm GeV}^{-1}/(10^{-22}{\rm eV})$. Both bounds scale as $(\rho/\rho_{\rm dm})^{1/2}$ if the energy density $\rho$ of the components is a fraction of the total dark matter energy density $\rho_{\rm dm}$. We do a detailed study of both effects using data from two samples of pulsars in the galaxy and in globular clusters, as well as data from FRB 121102 and PSR J0437$-$4715. We show that in both cases actual pulsar data constrain a new region of the parameter space for these models, and will improve with future pulsar-timing observations.Comment: 6 pages, 2 figures; v3: to appear on PR

Women's Participation in Cardiovascular Clinical Trials From 2010 to 2017

Background: Cardiovascular disease is the leading cause of death among women worldwide, yet, women have historically been underrepresented in cardiovascular trials. Methods: We systematically assessed the participation of women in completed cardiovascular trials registered in ClinicalTrials.gov between 2010 and 2017, and extracted publicly available information including disease type, sponsor type, country, trial size, intervention type, and the demographic characteristics of trial participants. We calculated the female-to-male ratio for each trial and determined the prevalence-adjusted estimates for participation of women by dividing the percentage of women among trial participants by the percentage of women in the disease population (participation prevalence ratio; a ratio of 0.8 to 1.2 suggests comparable prevalence and good representation). Results: We identified 740 completed cardiovascular trials including a total of 862 652 adults, of whom 38.2% were women. The median female-to-male ratio of each trial was 0.51 (25th quartile, 0.32; 75th quartile, 0.90) overall and varied by age group (1.02 in ≤55 year old group versus 0.40 in the 61- to 65-year-old group), type of intervention (0.44 for procedural trials versus 0.78 for lifestyle intervention trials), disease type (0.34 for acute coronary syndrome versus 3.20 for pulmonary hypertension), region (0.45 for Western Pacific versus 0.55 for the Americas), funding/sponsor type (0.14 for government-funded versus 0.73 for multiple sponsors), and trial size (0.56 for smaller [n≤47] versus 0.49 for larger [n≥399] trials). Relative to their prevalence in the disease population, participation prevalence ratio was higher than 0.8 for hypertension, pulmonary arterial hypertension and lower (participation prevalence ratio 0.48 to 0.78) for arrhythmia, coronary heart disease, acute coronary syndrome, and heart failure trials. The most recent time period (2013 to 2017) saw significant increases in participation prevalence ratios for stroke (P=0.007) and heart failure (P=0.01) trials compared with previous periods. Conclusions: Among cardiovascular trials in the current decade, men still predominate overall, but the representation of women varies with disease and trial characteristics, and has improved in stroke and heart failure trials

Hypertension in China: burdens, guidelines and policy responses: a state-of-the-art review.

Hypertension is a leading risk factor of cardiovascular disease and it is becoming increasingly prevalent globally. Correspondingly, the Chinese government and public health institutions have issued a series of policy documents and guidelines for hypertension. However, no comprehensive review of such documents has been conducted. Hence, this review aims to provide an up-to-date and comprehensive assessment of not only the disease burden, but also hypertension management policies and guidelines in China. A total of 15 epidemiological studies based on national population surveys, 15 Chinese Hypertension Guidelines, and seven policy documents were identified. We found a larger burden of hypertension in men, while the awareness, treatment, and control rates have remained low in both sexes. The ranges of hypertension prevalence, awareness, treatment, and control rate among hypertensive patients were 18.0-44.7%, 23.6-56.2%, 14.2-48.5%, and 4.2-30.1% respectively. Chinese hypertension guidelines provide evidence-based instructions to healthcare practitioners over hypertension management in which primary healthcare is increasingly emphasized. Finally, the policy documents set national goals for hypertension management and standardized the services provided in primary healthcare. The findings highlight the importance of integrating new guidelines into hypertension management provided by primary healthcare practitioners and the need to evaluate the implementation of guidelines and policies

A feasibility study on using smartphones to conduct short-version verbal autopsies in rural China

Background: Currently there are two main sources of mortality data with cause of death assignments in China. Both sources-the Ministry of Health-Vital Registration system and the Chinese Disease Surveillance Point system-present their own challenges. A new approach to cause of death assignment is a smartphone-based shortened version of a verbal autopsy survey. This study evaluates the feasibility and acceptability of this new method conducted by township health care providers (THP) and village doctors (VD) in rural China, where a large proportion of deaths occur in homes and cause of death data are inaccurate or lacking. Methods: The Population Health Metrics Research Consortium mobile phone-based shortened verbal autopsy questionnaire was made available on an Android system-based application, and cause of death was derived using the Tariff method (Tariff 2.0); we called this set of tools "msVA." msVA was administered to relatives of the deceased by six THPs and six VDs in 24 villages located in six townships of Luquan County, Hebei Province, China. Subsequently, interviews were conducted among 12 interviewers, 12 randomly selected respondents, and five study staff to assess the feasibility and acceptability of using msVA for mortality data collection. Results: Between July 2013 and August 2013, 268 deaths took place in the study villages. Among the 268 deaths, 227 VAs were completed (nine refusals, 31 migrations and one loss of data due to breakdown of the smartphone). The average time for a VA interview was 21.5 +/- 3.4 min (20.1 +/- 3.5 min for THP and 23.2 +/- 4.1 min for VD). Both THPs and VDs could be successful interviewers; the latter needed more training but had more willingness to implement msVA in the future. The interviews revealed that both interviewers and relatives of the deceased found msVA to be feasible, acceptable, and more desirable than traditional methods. The cost of conducting a new VA was $ 8.87 per death. Conclusions: Conduction of msVA by VDs in their own villages was feasible and acceptable in rural northern China. Broader implementation of msVA across rural China could potentially improve the coverage and quality of cause of death data, allowing for better national health evaluation and program planning.National Heart, Lung and Blood Institute, National Institutes of Health, Department of Health and Human Services [HHSN268200900034C]; NHLBI-UHG Trainee Seed [email protected]

An economic evaluation of a primary care-based technology-enabled intervention for stroke secondary prevention and management in rural China : a study protocol

Introduction: Secondary prevention of stroke is a leading challenge globally and only a few strategies have been tested to be effective in supporting stroke survivors. The system-integrated and technology-enabled model of care (SINEMA) intervention, a primary care-based and technology-enabled model of care, has been proven effective in strengthening the secondary prevention of stroke in rural China. The aim of this protocol is to outline the methods for the cost-effectiveness evaluation of the SINEMA intervention to better understand its potential economic benefits. Methods: The economic evaluation will be a nested study based on the SINEMA trial; a cluster-randomized controlled trial implemented in 50 villages in rural China. The effectiveness of the intervention will be estimated using quality-adjusted life years for the cost-utility analysis and reduction in systolic blood pressure for the cost-effectiveness analysis. Health resource and service use and program costs will be identified, measured, and valued at the individual level based on medication use, hospital visits, and inpatients' records. The economic evaluation will be conducted from the perspective of the healthcare system. Conclusion: The economic evaluation will be used to establish the value of the SINEMA intervention in the Chinese rural setting, which has great potential to be adapted and implemented in other resource-limited settings

Excess mortality among patients with severe mental disorders and effects of community-based mental healthcare: a community-based prospective study in Sichuan, China.

BACKGROUND: High-quality primary care reduces premature mortality in the general population, but evidence for psychiatric patients in China is scarce. AIMS: To confirm excess mortality in patients with severe mental illness (SMI), and to examine the impact of community-based mental healthcare and other risk factors on their mortality. METHOD: We included 93 655 patients in 2012 and 100 706 in 2013 from the national mental health surveillance system in Sichuan, China to calculate the standardised mortality ratio (SMR). A total of 112 576 patients were followed up from 2009 to 2014 for model analyses. We used growth models to quantify the patterns of change for community management measures, high-risk behaviour, disease stability and medication adherence of patients over time, and then used multilevel proportional hazard models to examine the association between change patterns of management measures and mortality. RESULTS: The SMR was 6.44 (95% CI 4.94-8.26) in 2012 and 7.57 (95% CI 5.98-9.44) in 2013 among patients with SMI aged 15-34 years, and diminished with age. Unfavourable baseline socioeconomic status increased the hazard of death by 38-50%. Positive changes in high-risk behaviour, disease stability and medication adherence had a 54% (95% CI 47-60%), 69% (95% CI 63-73%) and 20% (4-33%) reduction in hazard of death, respectively, versus in those where these were unchanged. CONCLUSIONS: High excess mortality was confirmed among younger patients with SMI in Sichuan, China. Our findings on the relationships between community management and socioeconomic factors and mortality can inform community-based mental healthcare policies to reduce excess mortality among patients with SMI

Intensity of Left Atrial Spontaneous Echo Contrast as a Correlate for Stroke Risk Stratification in Patients with Nonvalvular Atrial Fibrillation.

The intensity of left atrial spontaneous echo contrast (LASEC) by transesophageal echocardiography (TEE) has been proposed as an important variable in the stratification of thromboembolic risk, particularly in patients with nonvalvular atrial fibrillation (NVAF). We hypothesized that the quantification of LASEC by ultrasound will improve its utility in predicting subsequent stroke events in patients with NVAF. Patients (n = 206) with definite NVAF receiving TEE were included for this prospective cohort study. Baseline clinical risk factors of stroke, CHADS2 score and CHA2DS2-Vasc, left atrial thrombus (LAT), the five-grades of LASEC and video intensity (VI) value of LASEC were measured. During 2 years follow-up, 20 patients (9.7%) developed stroke. VI value of LASEC in the patients with stroke was higher compared to patients without stroke (25.30 ± 3.61 vs. 8.65 ± 0.81, p \u3c 0.001). On logistic regression analysis, LAT, qualitative LASEC, graded LASEC, VI value of LASEC and CHADS2 and CHA2DS2-Vasc score were independent predictors of stroke. Among them, the highest area under the curve of receiver operating characteristic (ROC) in predicting stroke was VI value of LASEC (p \u3c 0.05). These results show that quantification of LASEC by VI value is the most favorable predictor of stroke in patients with NVAF, and calls for improving the utility of LASEC in predicting subsequent stroke events