We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure coreplatform@cambridge.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
We study the effect of insoluble surfactants on the spatio-temporal evolution of turbulent jets. We use three-dimensional numerical simulations and employ an interface-tracking/level-set method that accounts for surfactant-induced Marangoni stresses. The present study builds on our previous work (Constante-Amores et al., J. Fluid Mech., vol. 922, 2021, A6) in which we examined in detail the vortex–surface interaction in the absence of surfactants. Numerical solutions are obtained for a wide range of Weber and elasticity numbers in which vorticity production is generated by surface deformation and surfactant-induced Marangoni stresses. The present work demonstrates, for the first time, the crucial role of Marangoni stresses, brought about by surfactant concentration gradients, in the formation of coherent, hairpin-like vortex structures. These structures have a profound influence on the development of the three-dimensional interfacial dynamics. We also present theoretical expressions for the mechanisms that influence the rate of production of circulation in the presence of surfactants for a general, three-dimensional, two-phase flow, and highlight the dominant contribution of surfactant-induced Marangoni stresses.
In this work, we study the effect of insoluble surfactants on the three-dimensional rim-driven retraction dynamics of thin water sheets in air. We employ an interface-tracking/level-set method to ensure the full coupling between the surfactant-induced Marangoni stresses, interfacial diffusion and inertia. Our findings are contrasted with the (Newtonian) dynamics of a liquid sheet edge, finding that the surfactant concentration can delay, or effectively prevent, the breakup of the rim. Our simulations use the fastest growing Rayleigh–Plateau instability to drive droplet detachment from the fluid sheet (rim). The results of this work unravel the significant role of Marangoni stresses in the retracting sheet dynamics at large elasticity numbers. We study the sensitivity of the dynamics to the elasticity number and the rigidification of the interface.
Dietary fibre modulates gastrointestinal (GI) health and function, providing laxation, shifting microbiota, and altering bile acid (BA) metabolism. Fruit juice production removes the polyphenol- and fibre-rich pomace fraction. The effects of orange and apple pomaces on GI outcomes were investigated in healthy, free-living adults. Healthy adults were enrolled in two double-blinded, crossover trials, being randomised by baseline bowel movement (BM) frequency. In the first trial, subjects (n 91) received orange juice (OJ, 0 g fibre/d) or OJ + orange pomace (OJ + P, 10 g fibre/d) for 4 weeks, separated by a 3-week washout. Similarly, in the second trial, subjects (n 90) received apple juice (AJ, 0 g fibre/d) or AJ + apple pomace (AJ + P, 10 g fibre/d). Bowel habit diaries, GI tolerance surveys and 3-d diet records were collected throughout. Fresh faecal samples were collected from a participant subset for microbiota and BA analyses in each study. Neither pomace interventions influenced BM frequency. At Week 4, OJ + P tended to increase (P = 0·066) GI symptom occurrence compared with OJ, while AJ + P tended (P = 0·089) to increase flatulence compared with AJ. Faecalibacterium (P = 0·038) and Negativibacillus (P = 0·043) were differentially abundant between pre- and post-interventions in the apple trial but were no longer significant after false discovery rate (FDR) correction. Baseline fibre intake was independently associated with several microbial genera in both trials. Orange or apple pomace supplementation was insufficient to elicit changes in bowel habits, microbiota diversity or BA of free-living adults with healthy baseline BM. Future studies should consider baseline BM frequency and habitual fibre intake.
University and college students are vulnerable to developing depressive symptoms. People in low-income countries are disproportionately impacted by mental health problems, yet few studies examine routes to accessing clinical services. Examining motivation and barriers toward seeking clinical mental health services in university students in Bangladesh is important.
Method
Using a cross-sectional survey (n = 350), we assess the relationship between the constructs of autonomy, relatedness, and competency toward using clinical mental health practices (i.e. using professional resources, taking medication) with (1) positive views, (2) perceived need, and (3) use of clinical mental health services among Bangladeshi university students.
Results
Results showed that the perceived need for mental health support was the predictor of the largest magnitude (aOR = 4.99, p = 0.005) for using clinical services. Having a positive view of clinical services was predictive of clinical service use (aOR = 2.87, p = 0.033); however, that association became insignificant (p = 0.054) when adjusting for the perceived need for mental health care. Of the SDT constructs, social influences were predictive of perceiving a need for mental health support, and mental health knowledge was predictive (aOR = 1.10, p = 0.001) of having a positive view of clinical mental health care.
Conclusion
Our findings show that knowledge of mental health is associated with positive views of mental health services, and that higher levels of stress and the presence of people with mental health problems are associated with the perception of a need for mental health care, which is ultimately responsible for using the services.
In problem-based learning (PBL), students are presented with a driving question that is open-ended, without an obvious linear path to a solution. In PBL children solve authentic real-world problems while engaging in disciplinary-appropriate practices. Rather than memorizing information, students learn while engaged in an authentic process of exploring data, arguments, and explanations, and formulating their own hypotheses and tentative solutions. Students explore the driving question by participating in scaffolded practices that help them to define a problem statement and a path toward a solution. Students create a set of tangible products that address the driving question, supporting collaboration and metacognition. Research shows that PBL promotes student engagement, improves academic learning, and enhances social emotional learning. In particular, PBL promotes science learning for all students, including students who historically have not had access to STEM careers.
Intense acoustic loads from jet noise cause noise pollution and induce failures, such as the malfunctioning of electronic devices and fatigue failure of internal/external structures. Consequently, the prediction of jet noise characteristics is crucial in the development of high-speed vehicles. This study presents acoustic experiments and predictions for an under-expanded, unheated jet using a small-scale prototype. Outdoor measurements are carried out using a vertical ejection setup. Acoustic characteristics are measured using both linear and circular microphone arrays. Additionally, numerical prediction of the same jet noise is performed using a detached eddy simulation and the permeable Ffowcs-Williams and Hawkings acoustic analogy. The vertical experimental setup exhibits the typical acoustic characteristics of a supersonic jet in terms of directivity and broadband shock-associated noise. Moreover, the numerical prediction exhibits satisfactory accuracy for the jet downstream, where the large-scale turbulence structures of the directivity predominate. However, discrepancy increases in the domain of lower directivity. The presented experiment and prediction will be extended to future studies regarding the noise of various deflector duct configurations impinging on supersonic jets.
The aim of this paper is to provide preliminary results on a traffic coordination framework based on stochastic task allocation. General trends and the predicted advent of personal aerial vehicles increase traffic rapidly, but current air traffic management methods admittedly cannot scale appropriately. A hierarchical system is proposed to overcome the problem, the middle layer of which is elaborated in this paper. This layer aims to enable stochastic control of traffic behaviour using a single parameter, which is achieved by applying distributed stochastic task allocation. The task allocation algorithm is used to allocate speeds to vehicles in a scalable way. By regulating the speed distribution of vehicles the conflict rates remain manageable. Multi-agent simulation results show that it is possible to control ensemble dynamics and together with that traffic safety and throughput via a single parameter. Using transient simulations the dynamic performance of the system is analysed. It is shown that the traffic conflict reduction problem can be transformed into a control design problem. The performance of a simple controller is also evaluated. It was shown that by applying the controller, quicker transients can be achieved for the mean speed of the system.
To assess the training and the future workforce needs of paediatric cardiac critical care faculty.
Design:
REDCap surveys were sent May−August 2019 to medical directors and faculty at the 120 US centres participating in the Society of Thoracic Surgeons Congenital Heart Surgery Database. Faculty and directors were asked about personal training pathway and planned employment changes. Directors were additionally asked for current faculty numbers, expected job openings, presence of training programmes, and numbers of trainees. Predictive modelling of the workforce was performed using respondents’ data. Patient volume was projected from US Census data and compared to projected provider availability.
Measurements and main results:
Sixty-six per cent (79/120) of directors and 62% (294/477) of contacted faculty responded. Most respondents had training that incorporated critical care medicine with the majority completing training beyond categorical fellowship. Younger respondents and those in dedicated cardiac ICUs were more significantly likely to have advanced training or dual fellowships in cardiology and critical care medicine. An estimated 49–63 faculty enter the workforce annually from various training pathways. Based on modelling, these faculty will likely fill current and projected open positions over the next 5 years.
Conclusions:
Paediatric cardiac critical care training has evolved, such that the majority of faculty now have dual fellowship or advanced training. The projected number of incoming faculty will likely fill open positions within the next 5 years. Institutions with existing or anticipated training programmes should be cognisant of these data and prepare graduates for an increasingly competitive market.
We study the effect of surfactants on the dynamics of a drop-interface coalescence using full three-dimensional direct numerical simulations. We employ a hybrid interface-tracking/level-set method, which takes into account Marangoni stresses that arise from surface-tension gradients, interfacial and bulk diffusion and sorption kinetic effects. We validate our predictions against the experimental data of Blanchette and Bigioni (Nat. Phys., vol. 2, issue 4, 2006, pp. 254–257) and perform a parametric study that demonstrates the delicate interplay between the flow fields and those associated with the surfactant bulk and interfacial concentrations. The results of this work unravel the crucial role of the Marangoni stresses in the flow physics of coalescence, with particular attention paid to their influence on the neck reopening dynamics in terms of stagnation-point inhibition, and near-neck vorticity generation. We demonstrate that surfactant-laden cases feature a rigidifying effect on the interface compared with the surfactant-free case, a mechanism that underpins the observed surfactant-induced phenomena.
While coronavirus disease 2019 (COVID-19) spreads across the globe, many countries have closed schools to ensure physical distancing to slow transmission and ease the burden on health systems. Concerns regarding Coronavirus Disease 2019 (COVID-19) school closures often increase stress levels in parents.
Objectives
This study examined whether higher levels of parental concerns were associated with children’s problematic behaviors and other factors during COVID-19-related primary school closures.
Methods
Participants were 217 parents who responded to a web-based questionnaire covering parental concerns, subjective stress, and depression; children’s sleep patterns, behavioral problems, and changes in activity level after COVID-19; previously received mental health services; and media usage during the online-only class period from community center in Suwon city.
Results
The number of parental concerns was associated with children’s behavioral problem index (BPI) score (Pearson correlation 0.211, p < 0.01), sleep problems (0.183, p < 0.01), increased smartphone usage (0.166, p < 0.05), increased TV usage (0.187, p < 0.01), parents’ subjective stress levels (0.168, p < 0.05), and parental depression (0.200, p < 0.01). In families with children who previously received mental health services, the children reportedly suffered from more sleep and behavioral problems but not increased media usage, and parents noted more stress and depression. Parental concerns are related to family factors such as change of caregiver, no available caregiver, decreased household income, and recent adverse life events.
Conclusions
Ongoing monitoring of mental health at risky group and multiple support systems should be considered for parents having difficulty in caring their children.
The breakup of an interface into a cascade of droplets and their subsequent coalescence is a generic problem of central importance to a large number of industrial settings such as mixing, separations and combustion. We study the breakup of a liquid jet introduced through a cylindrical nozzle into a stagnant viscous phase via a hybrid interface-tracking/level-set method to account for the surface tension forces in a three-dimensional Cartesian domain. Numerical solutions are obtained for a range of Reynolds ($Re$) and Weber ($We$) numbers. We find that the interplay between the azimuthal and streamwise vorticity components leads to different interfacial features and flow regimes in $Re$–$We$ space. We show that the streamwise vorticity plays a critical role in the development of the three-dimensional instabilities on the jet surface. In the inertia-controlled regime at high $Re$ and $We$, we expose the details of the spatio-temporal development of the vortical structures affecting the interfacial dynamics. A mushroom-like structure is formed at the leading edge of the jet inducing the generation of a liquid sheet in its interior that undergoes rupture to form droplets. These droplets rotate inside the mushroom structure due to their interaction with the prevailing vortical structures. Additionally, Kelvin–Helmholtz vortices that form near the injection point deform in the streamwise direction to form hairpin vortices, which, in turn, trigger the formation of interfacial lobes in the jet core. The thinning of the lobes induces the creation of holes which expand to form liquid threads that undergo capillary breakup to form droplets.
We study the effect of surfactant on the dynamics of a bubble bursting through an interface. We perform fully three-dimensional direct numerical simulations using a hybrid interface-tracking/level-set method accounting for surfactant-induced Marangoni stresses, sorption kinetics and diffusive effects. We select an initial bubble shape corresponding to a large Laplace number and a vanishingly small Bond number in order to neglect gravity, and isolate the effects of surfactant on the flow. Our results demonstrate that the presence of surfactant affects the dynamics of the system through Marangoni-induced flow, driving motion from high to low concentration regions, which is responsible for the onset of a recirculation zone close to the free surface. These Marangoni stresses rigidify the interface, delay the cavity collapse and influence the jet breakup process.
To determine the association between food insecurity and HIV infection with depression and anxiety among new tuberculosis (TB) patients.
Design:
Our cross-sectional study assessed depression, anxiety and food insecurity with Patient Health Questionnaire (PHQ-9), Zung Anxiety Self-Assessment Scale (ZUNG) and Household Food Insecurity Access Scale, respectively. Poisson regression models with robust variance were used to examine correlates of depression (PHQ-9 ≥ 10) and anxiety (ZUNG ≥ 36).
Setting:
Gaborone, Botswana.
Participants:
Patients who were newly diagnosed with TB.
Results:
Between January and December 2019, we enrolled 180 TB patients from primary health clinics in Botswana. Overall, 99 (55·0 %) were HIV positive, 47 (26·1 %), 85 (47·2 %) and 69 (38·5 %) indicated depression, anxiety and moderate to severe food insecurity, respectively. After adjusting for potential confounders, food insecurity was associated with a higher prevalence of depression (adjusted prevalence ratio (aPR) = 2·30; 95 % CI 1·40, 3·78) and anxiety (aPR = 1·41; 95 % CI 1·05, 1·91). Prevalence of depression and anxiety was similar between HIV-infected and HIV-uninfected participants. Estimates remained comparable when restricted to HIV-infected participants.
Conclusions:
Mental disorders may be affected by food insecurity among new TB patients, regardless of HIV status.
This essay explores how the term ‘girl,’ or 少女 (sonyŏ), in 1930s colonial Korean society simultaneously created and resisted homogeneity. We analyze the different contexts and cultural forces that shaped the term ‘girl’ in colonial Korea in order to illustrate some phases of the relationships that historical girls of colonial Korea had with their nation and state, the nation, that is, to which they thought they belonged at births and the state for which they were mobilized while they were systematically otherized. In our examination, we scrutinize the ways in which the subjectivities of colonial girls were ideologically forged through educational and institutional interventions and cultural interpellation. The first section discusses the concept of the girl in colonial Korea. The second part analyzes the various ideological functions that school textbooks played in gender-specific inculcation of colonial state ideals. We then read the ways The Chosŏn Ilbo (Chosŏn Daily) used the term the ‘girl’ in the 1930s, the period when the conceptual distinction between children and adults was further solidified, and the call on children was gender-specific in public. We finally elucidate the colonial processes of which girls of colonial Korea became part, albeit unknowingly.
The aeroelastic phenomenon of limit-cycle oscillations (LCOs) is analysed using a projection-based reduced-order model (PROM) and Navier–Stokes computational fluid dynamics (CFD) in the time domain. The proposed approach employs incompressible Navier–Stokes CFD to construct the full-order model flow field. A proper orthogonal decomposition (POD) of the snapshot matrix is conducted to extract the POD modes and corresponding temporal coefficients. The POD modes are directly projected to the incompressible Navier–Stokes equation to reconstruct the flow field efficiently. The methodology is applied to a plunging cylinder and an aerofoil undergoing LCOs. This scheme decreases the computational time while preserving the capability to predict the flow field accurately. The ROM is capable of reducing the computational time by at least 70% while maintaining the discrepancy within 0.1%. The causes of LCOs are also investigated. The scheme can be used to analyse non-linear aeroelastic phenomena in the time domain with reduced computational time.
To utilise a community-based participatory approach in the design and implementation of an intervention targeting diet-related health problems on Navajo Nation.
Design:
A dual strategy approach of community needs/assets assessment and engagement of cross-sectorial partners in programme design with systematic cyclical feedback for programme modifications.
Setting:
Navajo Nation, USA.
Participants:
Navajo families with individuals meeting criteria for programme enrolment. Participant enrolment increased with iterative cycles.
Results:
The Navajo Fruit and Vegetable Prescription (FVRx) Programme.
Conclusions:
A broad, community-driven and culturally relevant programme design has resulted in a programme able to maintain core programmatic principles, while also allowing for flexible adaptation to changing needs.
Pharmacogenomics (PGx) testing, in particular combinatorial PGx testing, represents a potential means for delivering personalized treatment selection for patients with psychiatric disorders. The goal of this educational intervention was to educate clinicians about the role of PGx testing in neuropsychiatric conditions such as MDD, how these novel tests may be implemented into clinical practice, and how results may be used to inform decision-making.
Method:
Psychiatrists (n=830) participated in an online enduring CME activity on PGx testing in psychiatric disorders
• The format was a 30-minute 2-person discussion (launched December 7, 2018)
• Data from this activity were collected for 30 days after launch
• Effectiveness of education for the CME activities was analyzed using 3 multiple-choice and 1 self-efficacy question (5-point Likert-type scale), presented as pre-/post-CME repeated pairs
• A paired samples t-test was conducted to examine improvements in mean confidence pre and post
Participant knowledge, competence, and confidence change in pre- to post-CME responses were calculated
Results:
Overall, 72% of psychiatrists (n=830) had knowledge or competence that was reinforced or improved as a result of education.
Following education:
* 56% and 12% of psychiatrists had reinforcement and improvement, respectively, in knowledge related to the clinical benefits of PGx-guided treatment strategies
• 61% and 8% of psychiatrists had reinforcement and improvement, respectively, in competence related to interpreting PGx tests for patients with neuropsychiatric disorders
• Within the group of psychiatrists with reinforced and improved knowledge/competence, there was a 30% increase in their confidence using PGx tests to help guide treatment decisions for patients with major depressive disorder (MDD) (M pre=2.14, post=2.77, scale 1 to 5)
• Confidence in the use of PGx testing was correlated with likelihood of considering PGx testing for patients with MDD
Conclusions:
Online CME aided in psychiatrists’ knowledge, competence, and confidence in using pharmacogenomics testing in patients with psychiatric disorders.
Funding Acknowledgements:
Supported by an independent educational grant from Myriad Neuroscience, formerly Assurex Health
The aim of this study was to examine whether the presence of risk alleles of the norepinephrine transporter gene (SLC6A2) polymorphisms is associated with differences in regional cerebral blood flow (rCBF) measured by 99mTc-HMPAO single photon emission computerized tomography in a Korean sample of ADHD.
Methods
The present study included 24 children with ADHD (9.5±2.4 years), consisting of 20 boys and 4 girls, aged 6-16 years. We investigated the G1287A and -3081(A/T) polymorphisms of the SLC6A2. The rCBF was compared between the ADHD subjects with and without risk alleles at the G1287A polymorphism and at the -3081(A/T) polymorphism. Image analyses were performed with voxelwise t-statistics using SPM2.
Results
1) The ADHD subjects with the A allele (risk allele) at the G1287A polymorphism showed reduced perfusion in the left middle frontal gyrus, left inferior parietal lobule, precuneus, right superior frontal gyrus, and right superior parietal lobule as compared with ADHD subjects without the A allele (p< 0.001).
2) The ADHD subjects with the A allele at the G1287A polymorphism showed increased perfusion in the right middle frontal gyrus, right middle temporal gyrus, right superior temporal gyrus, right fusiform gyrus, right precentral gyrus, and right anterior lobe of cerebellum as compared with ADHD subjects without the A allele (p< 0.001).
3) No significant perfusion differences were found between ADHD subjects with and without the T allele (risk allele) at the -3081(A/T) polymorphism.
Conclusion
Our findings suggest that the SLC6A2 G1287A polymorphism might exert differential effects on rCBF in children with ADHD.
There have been many changes in the treatment of bipolar disorder.
Objective
It is necessary to develop guidelines that can more aptly respond to cultural issues and specifics in different countries.
Aims
The Korean Medication Algorithm for Bipolar Disorder (KMAP-BP) was firstly published in 2002, with updates in 2006 and 2010. This third update reviewed the experts' consensus of opinion on the pharmacological treatments of bipolar disorder.
Methods
The newly revised questionnaire composed of 55 key questions about clinical situations including 223 sub-items was sent to the experts.
Results
Combination of mood stabilizer (MS) and atypical antipsychotic (AAP) was the first-line treatment option in acute mania. For the management of severe psychotic bipolar depression, combination of MS and AAP, combination of AAP and LTG, combination of MS, AAP and AD or LTG, combination of AAP and AD, and combination of AAP, AD and LTG was the first-line treatments. Combination of MS and AAP was the treatment of choice for management of mixed features. Combination of MS and AAP, MS or AAP monotherapy was the first-line options for management of maintenance phase after manic episode. For maintenance treatment after bipolar I depression, combination of MS and AAP, combination of MS and LTG, combination of AAP and LTG, MS or LTG monotherapy, and combination of MS, AAP and LTG were the first-line options.
Conclusion
Despite the limitations of expert consensus guideline, KMAP-BP 2014 may reflect the current patterns of clinical practice and recent researches.
Brain health has garnered increasing attention as a requisite condition for healthy aging. The rapid growth in mobile health and increasing smartphone ownership among older adults has paved the way for smartphones to be utilized as effective tools for improving mental fitness.
Objectives
There are few studies that have explored the efficacy of smartphone-based cognitive training. The present study examined the memory-enhancing effects of smartphone-based memory training for older adults.
Aims
We explored whether newly developed application “Smartphone-based brain Anti-aging and memory Reinforcement Training (SMART)” improved memory performance in older adults with subjective memory complaints.
Methods
A total of 53 adults (mean age: 59.3 years) were randomised into either one of two smartphone-based intervention groups (SMART vs. Fit Brains®) or a wait-list group. Participants in the intervention groups underwent 15–20 minutes of training per day, five days per week for 8 weeks. We used objective cognitive measures to evaluate changes with respect to four domains: attention, memory, working memory (WM), and executive function (inhibition, fluency, etc.). In addition, we included self-report questionnaires to assess levels of subjective memory complaints.
Results
The performance on WM test increased significantly in the SMART group (t[17] = 6.27, P < 0.0001) but not in the control groups. Self-reports of memory contentment, however, increased in the Fit Brains® group only (t[18] = 2.12, P = 0.048).
Conclusions
Use of an 8-week smartphone-based memory training program may improve working memory function in older adults. However, objective improvement in performance does not necessarily lead to decreased subjective memory complaints.
Disclosure of interest
The authors have not supplied their declaration of competing interest.