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Student's t test is valid for statistical inference under the normality assumption or asymptotically. By contrast, although the bootstrap t test was proposed in 1993, it is seldom adopted in medical research. We aim to demonstrate that the bootstrap t test outperforms Student's t test under normality in data. Using random data samples from normal distributions, we evaluated the testing performance, in terms of true-positive rate (TPR) and false-positive rate and diagnostic abilities, in terms of the area under the curve (AUC), of the bootstrap t test and Student's t test. We explore the AUC of both tests with varying sample size and coefficient of variation. We compare the testing outcomes using the COVID-19 serial interval (SI) data in Shenzhen and Hong Kong, China, for demonstration. With fixed TPR, the bootstrap t test maintained the equivalent accuracy in TPR, but significantly improved the true-negative rate from the Student's t test. With varying TPR, the diagnostic ability of bootstrap t test outperformed or equivalently performed as Student's t test in terms of the AUC. The equivalent performances are possible but rarely occur in practice. We find that the bootstrap t test outperforms by successfully detecting the difference in COVID-19 SI, which is defined as the time interval between consecutive transmission generations, due to sex and non-pharmaceutical interventions against the Student's t test. We demonstrated that the bootstrap t test outperforms Student's t test, and it is recommended to replace Student's t test in medical data analysis regardless of sample size.
High rates of physical and mental health comorbidities are associated with functional impairment among persons who are homeless. Cognitive dysfunction is common, but how it contributes to various functional outcomes in this population has not been well investigated. This study examines how cognition covaries with community functioning and subjective quality of life over a 6-year period while accounting for the effects of risk and protective factors.
Participants were 349 homeless adults (mean age = 39.8) recruited from the Toronto site of the At Home/Chez Soi study, a large Canadian randomized control trial of Housing First. Participants completed up to four clinical evaluations over 6 years. Factor scores were created to index verbal learning and memory (vLM) and processing speed-cognitive flexibility (PSCF). The primary outcomes were community functioning and subjective quality of life. Risk factors included lifetime homelessness, mental health diagnoses, medical comorbidity, and childhood adversity. Linear mixed-effects models were conducted to examine cognition-functional outcome associations over time, with resilience as a moderator.
Better vLM (b = 0.787, p = 0.010) and PSCF (b = 1.66, p < 0.001) were associated with better community functioning, but not with quality of life. Resilience conferred a protective effect on subjective quality of life (b = 1.45, p = 0.011) but did not moderate outcomes.
Our findings suggest a need to consider the unique determinants of community functioning and quality of life among homeless adults. Cognition should be prioritized as a key intervention target within existing service delivery models to optimize long-term functional outcomes.
Bioarchaeological research provides unique insights on human adaptation, diet, lifestyle and epidemiology. The Mogou Bioarchaeology Project explores how health was affected by the Bronze Age transition in north-west China. Preliminary results reveal that the inhabitants experienced substantial physiological stress, infectious disease and lethal trauma.
An experimental investigation was carried out in a low-turbulence wind tunnel to study the early development of artificially initiated turbulent spots in a laminar boundary layer over a flat plate. The reproducibility of the experiments allowed us to observe fine structural details that have not been observed previously. Initial velocity disturbances quickly developed into hairpin-like structures that multiplied downstream, which increased the width, length and height of the incipient turbulent spots. Only those disturbances that were greater than a threshold value developed into turbulent spots while the others decayed. The rate of development was also affected by the duration of the initial disturbances. We found that the behaviour of turbulence generation within a turbulent spot is similar to the burst events in the turbulent boundary layer, where ejection events are followed by sweep events.
We look at the effect of the WTO on stabilizing international trade using both a fixed-effects and an event study approach. Our results show that WTO members experience lower trade volatilties in a predictable and integrated system. In addition, we focus on the trade volatility comovement among countries in a multilateral framework. Previous research has mainly focused on WTO membership in a bilateral trade framework, which only allows interactions between two trade partners without considering any possible influence from other countries. A bilateral trade framework does not fully capture the effect of WTO membership, nor does it investigate why the multilateral platform of the WTO should exist. With a unique setup estimating interactions among multiple trading dyads, we find strong evidence supporting positive correlation or comovement of trade volatilities across trading pairs. Such a comovement appears much stronger among WTO members than between WTO and non-WTO members. Due to the feedback mechanism among dyads in a multilateral framework, such as the WTO, bilateral trade stability may further stabilize the global trade. Our results remain robust to a battery of sensitivity checks.
The accumulation of nutrients during diapause preparation is crucial because any lack of nutrition will reduce the likelihood of insects completing diapause, thereby decreasing their chances of survival and reproduction. The fall webworm, Hyphantria cunea, diapause as overwintering pupae and their diapause incidence and diapause intensity are regulated by the photoperiod. In this study, we test the hypothesis that photoperiod influences energy reserve accumulation during diapause preparation in fall webworm. We found that the body size and mass, lipid and carbohydrate content of pupae with a short photoperiod during the diapause induction phase were significantly greater than those of pupae with a relatively short photoperiod, and the efficiency of converting digested food and ingested food into body matter was greater in the short-photoperiod diapause-destined larvae than the relatively short-photoperiod diapause-destined larvae. We also observed higher lipase and amylase activities in short-photoperiod diapause-destined larvae relative to the counterparts. However, no obvious difference was found in protein and protease in the pupae with a short photoperiod during the diapause induction phase and short-photoperiod diapause-destined larvae compared with the counterparts. Therefore, we conclude that the energy reserve patterns of diapausing fall webworm pupae are plastic and that short-photoperiod diapause-destined larvae increase their energy reserves by improving their feeding efficiency and increase their lipid and carbohydrate stores by increasing the lipase and amylase activities in the midgut.
To assess extent of a healthcare-associated outbreak of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) and to evaluate the effectiveness of infection control measures, including universal masking.
Outbreak investigation including 4 large-scale point-prevalence surveys.
Integrated VA healthcare system with 2 facilities and 330 beds.
Index patient and 250 exposed patients and staff.
We identified exposed patients and staff and classified them as probable and confirmed cases based on symptoms and testing. We performed a field investigation and an assessment of patient and staff interactions to develop probable transmission routes. Infection prevention interventions included droplet and contact precautions, employee quarantine, and universal masking with medical and cloth face masks. We conducted 4 point-prevalence surveys of patient and staff subsets using real-time reverse-transcriptase polymerase chain reaction for SARS-CoV-2.
Among 250 potentially exposed patients and staff, 14 confirmed cases of coronavirus disease 2019 (COVID-19) were identified. Patient roommates and staff with prolonged patient contact were most likely to be infected. The last potential date of transmission from staff to patient was day 22, the day universal masking was implemented. Subsequent point-prevalence surveys in 126 patients and 234 staff identified 0 patient cases and 5 staff cases of COVID-19, without evidence of healthcare-associated transmission.
Universal masking with medical face masks was effective in preventing further spread of SARS-CoV-2 in our facility in conjunction with other traditional infection prevention measures.
Community characteristics, such as collective efficacy, a measure of community strength, can affect behavioral responses following disasters. We measured collective efficacy 1 month before multiple hurricanes in 2005, and assessed its association to preparedness 9 months following the hurricane season.
Participants were 631 Florida Department of Health workers who responded to multiple hurricanes in 2004 and 2005. They completed questionnaires that were distributed electronically approximately 1 month before (6.2005-T1) and 9 months after (6.2006-T2) several storms over the 2005 hurricane season. Collective efficacy, preparedness behaviors, and socio-demographics were assessed at T1, and preparedness behaviors and hurricane-related characteristics (injury, community-related damage) were assessed at T2. Participant ages ranged from 21-72 (M(SD) = 48.50 (10.15)), and the majority were female (78%).
In linear regression models, univariate analyses indicated that being older (B = 0.01, SE = 0.003, P < 0.001), White (B = 0.22, SE = 0.08, P < 0.01), and married (B = 0.05, SE = 0.02, p < 0.001) was associated with preparedness following the 2005 hurricanes. Multivariate analyses, adjusting for socio-demographics, preparedness (T1), and hurricane-related characteristics (T2), found that higher collective efficacy (T1) was associated with preparedness after the hurricanes (B = 0.10, SE = 0.03, P < 0.01; and B = 0.47, SE = 0.04, P < 0.001 respectively).
Programs enhancing collective efficacy may be a significant part of prevention practices and promote preparedness efforts before disasters.
A multi-agent engagement scenario is considered in which a high-value aircraft launches two defenders to intercept two homing missiles aimed at the aircraft. Under the assumption that all aircrafts have first-order linear dynamic characteristics, a combined multiple-mode adaptive estimation (MMAE) and a two-way cooperative optimal guidance law are proposed for the target–defenders team. Considering the full cooperation of the target and both the two defenders, the two-way cooperative strategies provide the analytical expressions for their optimal control input, enabling the target–defenders team to intercept the missiles with minimal control effort. To successfully intercept the missiles, MMAE is used to identify the guidance laws adopted by the missiles and estimate their states. The simulation results show that the target cooperating with the defenders to perform lure manoeuvres for the missiles can improve the guidance performance of the defenders as well as reduce the control effort of the defenders for intercepting the missiles.
Antipsychotics are widely used for treating patients with psychosis, and target threshold psychotic symptoms. Individuals at clinical high risk (CHR) for psychosis are characterized by subthreshold psychotic symptoms. It is currently unclear who might benefit from antipsychotic treatment. Our objective was to apply a risk calculator (RC) to identify people that would benefit from antipsychotics.
Drawing on 400 CHR individuals recruited between 2011 and 2016, 208 individuals who received antipsychotic treatment were included. Clinical and cognitive variables were entered into an individualized RC for psychosis; personal risk was estimated and 4 risk components (negative symptoms-RC-NS, general function-RC-GF, cognitive performance-RC-CP, and positive symptoms-RC-PS) were constructed. The sample was further stratified according to the risk level. Higher risk was defined based on the estimated risk score (20% or higher).
In total, 208 CHR individuals received daily antipsychotic treatment of an olanzapine-equivalent dose of 8.7 mg with a mean administration duration of 58.4 weeks. Of these, 39 (18.8%) developed psychosis within 2 years. A new index of factors ratio (FR), which was derived from the ratio of RC-PS plus RC-GF to RC-NS plus RC-CP, was generated. In the higher-risk group, as FR increased, the conversion rate decreased. A small group (15%) of CHR individuals at higher-risk and an FR >1 benefitted from the antipsychotic treatment.
Through applying a personal risk assessment, the administration of antipsychotics should be limited to CHR individuals with predominantly positive symptoms and related function decline. A strict antipsychotic prescription strategy should be introduced to reduce inappropriate use.
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.
The characteristic traits of maize (Zea mays L.) leaves affect light interception and photosynthesis. Measurement or estimation of individual leaf area has been described using discontinuous equations or bell-shaped functions. However, new maize hybrids show different canopy architecture, such as leaf angle in modern maize which is more upright and ear leaf and adjacent leaves which are longer than older hybrids. The original equations and their parameters, which have been used for older maize hybrids and grown at low plant densities, will not accurately represent modern hybrids. Therefore, the aim of this paper was to develop a new empirical equation that captures vertical leaf distribution. To characterize the vertical leaf profile, we conducted a field experiment in Jilin province, Northeast China from 2015 to 2018. Our new equation for the vertical distribution of leaf profile describes leaf length, width or leaf area as a function of leaf rank, using parameters for the maximum value for leaf length, width or area, the leaf rank at which the maximum value is obtained, and the width of the curve. It thus involves one parameter less than the previously used equations. By analysing the characteristics of this new equation, we identified four key leaf ranks (4, 8, 14 and 20) for which leaf parameter values need to be quantified in order to have a good estimation of leaf length, width and area. Together, the method of leaf area estimation proposed here adds versatility for use in modern maize hybrids and simplifies the field measurements by using the four key leaf ranks to estimate vertical leaf distribution in maize canopy instead of all leaf ranks.
The rotating instability in a contra-rotating axial flow compressor is investigated by experiments. Twenty-four pressure sensors were installed on the casing to capture the unsteady flow in the rotor tip region simultaneously. A double-phase-locking technique suitable for the contra-rotating compressor was proposed to characterise the static pressure contours of the rotor tip. The mean and root-mean-square pressure contours indicate that rotating instability occurs before the rotating stall happened, and the rotor tip clearance vortex is located upstream of the rear rotor leading edge plane before stall. Fourier spectrum shows that rotating instability and rotating stall both happened under the stall condition, and the frequency band of rotating instability does not change with the flow rate. In the front rotor, the frequency of rotating instability is half of the blade passing frequency. It is verified that the modal estimation method can be implemented by using the average azimuthal phase velocity, which significantly reduced the number of pressure sensors required. Modal estimation results show that each peak of the rotating instability frequency band corresponds to a unique dominant circumferential mode. By optimising average azimuthal phase velocity, an improved modal estimation method is obtained, which can further improve the reliability of the modal estimation results.
This study assesses the prevalence of childhood undernutrition from 2001 to 2016 and estimate projections of undernutrition for 2016–2030 in Nepal.
The study used data from four rounds of a cross-sectional survey of Nepal Demographic and Health Survey (NDHS) conducted in 2001, 2006, 2011 and 2016. Descriptive analyses were conducted to calculate prevalence, binary logistic regression was used to test the significance of trends over time and autoregressive integrated moving average model was used to forecast the prevalence of childhood undernutrition.
The children and household member datasets from four NDHS were merged to assess the trends of childhood undernutrition in Nepal.
A total of 16 613 children (8399 male and 8214 female) under 5 years of age were selected for anthropometric measurements using a stratified cluster random sampling method.
Overall results show a decline in prevalence of stunting from 57·2 % to 35·8 % (P < 0·001), underweight from 42·7 % to 27 % (P < 0·001) and wasting from 11·2 % to 9·7 % (P < 0·05) from 2001 to 2016. However, different population subgroups have a higher prevalence of undernutrition than national average. Further, the analyses show that the prevalence of stunting will decline to 14·3 % and wasting to 8·4 % by 2030.
A remarkable decrease in the prevalence of stunting and underweight has been observed over the last 15 years. Nepal is likely to achieve the nutritional targets for stunting but not for wasting by 2030. Given large subpopulation variations, further improvement in undernutrition require more specific, targeted and localised programmes.
To examine associations between diet and risk of developing gastro-oesophageal reflux disease (GERD).
Prospective cohort with a median follow-up of 15·8 years. Baseline diet was measured using a FFQ. GERD was defined as self-reported current or history of daily heartburn or acid regurgitation beginning at least 2 years after baseline. Sex-specific logistic regressions were performed to estimate OR for GERD associated with diet quality scores and intakes of nutrients, food groups and individual foods and beverages. The effect of substituting saturated fat for monounsaturated or polyunsaturated fat on GERD risk was examined.
A cohort of 20 926 participants (62 % women) aged 40–59 years at recruitment between 1990 and 1994.
For men, total fat intake was associated with increased risk of GERD (OR 1·05 per 5 g/d; 95 % CI 1·01, 1·09; P = 0·016), whereas total carbohydrate (OR 0·89 per 30 g/d; 95 % CI 0·82, 0·98; P = 0·010) and starch intakes (OR 0·84 per 30 g/d; 95 % CI 0·75, 0·94; P = 0·005) were associated with reduced risk. Nutrients were not associated with risk for women. For both sexes, substituting saturated fat for polyunsaturated or monounsaturated fat did not change risk. For both sexes, fish, chicken, cruciferous vegetables and carbonated beverages were associated with increased risk, whereas total fruit and citrus were associated with reduced risk. No association was observed with diet quality scores.
Diet is a possible risk factor for GERD, but food considered as triggers of GERD symptoms might not necessarily contribute to disease development. Potential differential associations for men and women warrant further investigation.
This study was a retrospective multicentre cohort study of patients with coronavirus disease 2019 (COVID-19) diagnosed at 24 hospitals in Jiangsu province, China as of 15 March 2020. The primary outcome was the occurrence of acute respiratory failure during hospital stay. Of 625 patients, 56 (9%) had respiratory failure. Some selected demographic, epidemiologic, clinical and laboratory features as well as radiologic features at admission and treatment during hospitalisation were significantly different in patients with and without respiratory failure. The multivariate logistic analysis indicated that age (in years) (odds ratio [OR], 1.07; 95% confidence interval [CI]: 1.03–1.10; P = 0.0002), respiratory rate (breaths/minute) (OR, 1.23; 95% CI: 1.08–1.40; P = 0.0020), lymphocyte count (109/l) (OR, 0.18; 95% CI: 0.05–0.69; P = 0.0157) and pulmonary opacity score (per 5%) (OR, 1.38; 95% CI: 1.19–1.61; P < 0.0001) at admission were associated with the occurrence of respiratory failure. Older age, increased respiratory rate, decreased lymphocyte count and greater pulmonary opacity score at admission were independent risk factors of respiratory failure in patients with COVID-19. Patients having these risk factors need to be intensively managed during hospitalisation.
COVID-19 has challenged the mental health of healthcare workers confronting it world-wide. Our study identifies the prevalence and risk of anxiety among emergency healthcare workers confronting COVID-19 in Pakistan. We conducted a cross-sectional survey in an Emergency Department using the Generalized Anxiety Scale (GAD-7), and questions about sources of anxiety. Of 107 participants, 61.7% were frontline workers. The prevalence of anxiety was 50.5%. Nonparametric tests determined that nurses, younger and inexperienced staff, developed significant anxiety. Multivariate ordinal regression determined independent risk factors for developing anxiety were younger age (OR 2.11, 95% CI 0.89–4.99) and frontline placement (OR 1.34, 95% CI 0.33–1.66). Significant sources of stress were fear of infecting family (P = 0.003), lack of social support when the health care providers were themselves unwell (P = 0.02) and feelings of inadequate work performance (P = 0.05). Our study finds that HCWs’ anxiety is considerable. Appropriate measures for its alleviation and prevention are required.
To investigate the influences of dietary riboflavin (RF) addition on nutrient digestion and rumen fermentation, eight rumen cannulated Holstein bulls were randomly allocated into four treatments in a repeated 4 × 4 Latin square design. Daily addition level of RF for each bull in control, low RF, medium RF and high RF was 0, 300, 600 and 900 mg, respectively. Increasing the addition level of RF, DM intake was not affected, average daily gain tended to be increased linearly and feed conversion ratio decreased linearly. Total tract digestibilities of DM, organic matter, crude protein (CP) and neutral-detergent fibre (NDF) increased linearly. Rumen pH decreased quadratically, and total volatile fatty acids (VFA) increased quadratically. Acetate molar percentage and acetate:propionate ratio increased linearly, but propionate molar percentage and ammonia-N content decreased linearly. Rumen effective degradability of DM increased linearly, NDF increased quadratically but CP was unaltered. Activity of cellulase and populations of total bacteria, protozoa, fungi, dominant cellulolytic bacteria, Prevotella ruminicola and Ruminobacter amylophilus increased linearly. Linear increase was observed for urinary total purine derivatives excretion. The data suggested that dietary RF addition was essential for rumen microbial growth, and no further increase in performance and rumen total VFA concentration was observed when increasing RF level from 600 to 900 mg/d in dairy bulls.