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We perform a numerical study of the heat transfer and flow structure of Rayleigh–Bénard (RB) convection in (in most cases regular) porous media, which are comprised of circular, solid obstacles located on a square lattice. This study is focused on the role of porosity
in the flow properties during the transition process from the traditional RB convection with
(so no obstacles included) to Darcy-type porous-media convection with
approaching 0. Simulations are carried out in a cell with unity aspect ratio, for Rayleigh number
and varying porosities
, at a fixed Prandtl number
, and we restrict ourselves to the two-dimensional case. For fixed
, the Nusselt number
is found to vary non-monotonically as a function of
; namely, with decreasing
, it first increases, before it decreases for
approaching 0. The non-monotonic behaviour of
originates from two competing effects of the porous structure on the heat transfer. On the one hand, the flow coherence is enhanced in the porous media, which is beneficial for the heat transfer. On the other hand, the convection is slowed down by the enhanced resistance due to the porous structure, leading to heat transfer reduction. For fixed
, depending on
, two different heat transfer regimes are identified, with different effective power-law behaviours of
, namely a steep one for low
when viscosity dominates, and the standard classical one for large
. The scaling crossover occurs when the thermal boundary layer thickness and the pore scale are comparable. The influences of the porous structure on the temperature and velocity fluctuations, convective heat flux and energy dissipation rates are analysed, further demonstrating the competing effects of the porous structure to enhance or reduce the heat transfer.
Gut microbiota data obtained by DNA sequencing are not only complex because of the number of taxa that may be detected within human cohorts, but also compositional because characteristics of the microbiota are described in relative terms (e.g., “relative abundance” of particular bacterial taxa expressed as a proportion of the total abundance of taxa). Nutrition researchers often use standard principal component analysis (PCA) to derive dietary patterns from complex food data, enabling each participant's diet to be described in terms of the extent to which it fits their cohort's dietary patterns. However, compositional PCA methods are not commonly used to describe patterns of microbiota in the way that dietary patterns are used to describe diets. This approach would be useful for identifying microbiota patterns that are associated with diet and body composition. The aim of this study is to use compositional PCA to describe gut microbiota profiles in 5 year old children and explore associations between microbiota profiles, diet, body mass index (BMI) z-score, and fat mass index (FMI) z-score. This study uses a cross-sectional data for 319 children who provided a faecal sample at 5 year of age. Their primary caregiver completed a 123-item quantitative food frequency questionnaire validated for foods of relevance to the gut microbiota. Body composition was determined using dual-energy x-ray absorptiometry, and BMI and FMI z-scores calculated. Compositional PCA identified and described gut microbiota profiles at the genus level, and profiles were examined in relation to diet and body size. Three gut microbiota profiles were found. Profile 1 (positive loadings on Blautia and Bifidobacterium; negative loadings on Bacteroides) was not related to diet or body size. Profile 2 (positive loadings on Bacteroides; negative loadings on uncultured Christensenellaceae and Ruminococcaceae) was associated with a lower BMI z-score (r = -0.16, P = 0.003). Profile 3 (positive loadings on Faecalibacterium, Eubacterium and Roseburia) was associated with higher intakes of fibre (r = 0.15, P = 0.007); total (r = 0.15, P = 0.009), and insoluble (r = 0.13, P = 0.021) non-starch polysaccharides; protein (r = 0.12, P = 0.036); meat (r = 0.15, P = 0.010); and nuts, seeds and legumes (r = 0.11, P = 0.047). Further regression analyses found that profile 2 and profile 3 were independently associated with BMI z-score and diet respectively. We encourage fellow researchers to use compositional PCA as a method for identifying further links between the gut, diet and obesity, and for developing the next generation of research in which the impact on body composition of dietary interventions that modify the gut microbiota is determined.
Neurodevelopment is sensitive to genetic and pre/postnatal environmental influences. These effects are likely mediated by epigenetic factors, yet current knowledge is limited. Longitudinal twin studies can delineate the link between genetic and environmental factors, epigenetic state at birth and neurodevelopment later in childhood. Building upon our study of the Peri/postnatal Epigenetic Twin Study (PETS) from gestation to 6 years of age, here we describe the PETS 11-year follow-up in which we will use neuroimaging and cognitive testing to examine the relationship between early-life environment, epigenetics and neurocognitive outcomes in mid-childhood. Using a within-pair twin model, the primary aims are to (1) identify early-life epigenetic correlates of neurocognitive outcomes; (2) determine the developmental stability of epigenetic effects and (3) identify modifiable environmental risk factors. Secondary aims are to identify factors influencing gut microbiota between 6 and 11 years of age to investigate links between gut microbiota and neurodevelopmental outcomes in mid-childhood. Approximately 210 twin pairs will undergo an assessment at 11 years of age. This includes a direct child cognitive assessment, multimodal magnetic resonance imaging, biological sampling, anthropometric measurements and a range of questionnaires on health and development, behavior, dietary habits and sleeping patterns. Data from complementary data sources, including the National Assessment Program — Literacy and Numeracy and the Australian Early Development Census, will also be sought. Following on from our previous focus on relationships between growth, cardiovascular health and oral health, this next phase of PETS will significantly advance our understanding of the environmental interactions that shape the developing brain.
Unlike for many other respiratory infections, the seasonality of pertussis is not well understood. While evidence of seasonal fluctuations in pertussis incidence has been noted in some countries, there have been conflicting findings including in the context of Australia. We investigated this issue by analysing the seasonality of pertussis notifications in Australia using monthly data from January 1991 to December 2016. Data were made available for all states and territories in Australia except for the Australian Capital Territory and were stratified into age groups. Using a time-series decomposition approach, we formulated a generalised additive model where seasonality is expressed using cosinor terms to estimate the amplitude and peak timing of pertussis notifications in Australia. We also compared these characteristics across different jurisdictions and age groups. We found evidence that pertussis notifications exhibit seasonality, with peaks observed during the spring and summer months (November–January) in Australia and across different states and territories. During peak months, notifications are expected to increase by about 15% compared with the yearly average. Peak notifications for children <5 years occurred 1–2 months later than the general population, which provides support to the theory that older household members remain an important source of pertussis infection for younger children. In addition, our results provide a more comprehensive spatial picture of seasonality in Australia, a feature lacking in previous studies. Finally, our findings suggest that seasonal forcing may be useful to consider in future population transmission models of pertussis.
The authors developed a practical and clinically useful model to predict the risk of psychosis that utilizes clinical characteristics empirically demonstrated to be strong predictors of conversion to psychosis in clinical high-risk (CHR) individuals. The model is based upon the Structured Interview for Psychosis Risk Syndromes (SIPS) and accompanying clinical interview, and yields scores indicating one's risk of conversion.
Baseline data, including demographic and clinical characteristics measured by the SIPS, were obtained on 199 CHR individuals seeking evaluation in the early detection and intervention for mental disorders program at the New York State Psychiatric Institute at Columbia University Medical Center. Each patient was followed for up to 2 years or until they developed a syndromal DSM-4 disorder. A LASSO logistic fitting procedure was used to construct a model for conversion specifically to a psychotic disorder.
At 2 years, 64 patients (32.2%) converted to a psychotic disorder. The top five variables with relatively large standardized effect sizes included SIPS subscales of visual perceptual abnormalities, dysphoric mood, unusual thought content, disorganized communication, and violent ideation. The concordance index (c-index) was 0.73, indicating a moderately strong ability to discriminate between converters and non-converters.
The prediction model performed well in classifying converters and non-converters and revealed SIPS measures that are relatively strong predictors of conversion, comparable with the risk calculator published by NAPLS (c-index = 0.71), but requiring only a structured clinical interview. Future work will seek to externally validate the model and enhance its performance with the incorporation of relevant biomarkers.
Introduction: The risk of recurrent stroke following a transient ischemic attack (TIA) has been estimated to be as much as 5 percent in the first 48 hours and ten percent in the first week following initial TIA symptoms, but can be modified as a result of intensive risk factor management. Care pathways for these patients vary between different regions within Alberta with Edmonton admitting more TIA patients and Calgary using computed tomography angiography (CTA) based triage. To examine regional differences in the quality of care, the rate of admission for stroke within 90 days of an index ED visit for TIA/minor stroke was investigated. Methods: Data analysts from the Data Integration, Measurement and Reporting (DIMR) branch of Alberta Health Services (AHS) used the National Ambulatory Care Reporting System (NACRS) to identify patients in Alberta who were admitted for stroke within 90-days of an index emergency department (ED) visit for TIA/minor stroke from April 2010 to March 2016. Information extracted included patient demographics, region of residence (Edmonton, Calgary or non-major urban [NMU]), return diagnosis and timing of return ED visit. Analysis included descriptive summaries and proportions were compared using a χ2 test. Results: During the study period, there were 26,232 index visits to Alberta EDs for TIA/minor stroke. 5426 (26.1%) of patients were admitted on their index visit. Calgary (22.5%) had lower rates of admission on index visit followed by Edmonton (31.4%) and the NMU (46%). 20,806 (79.3%) were discharged home following their index visit. Of the patients discharged on their index visit 729 (3.5%) had an admission for stroke within 90-days of their index ED visit with rates in Edmonton (3.8%) and the NMU regions (3.8%) being significantly higher than Calgary (2.8%, p<0.01). Conclusion: Our study demonstrates significantly lower rates of admission for stroke within 90-days of ED visit for minor stroke/TIA in Calgary compared to Edmonton and the NMU. Further work should focus on validating this result and consideration of standardized care pathways that promote effective resource utilization and quality of care.
The development of metal–organic frameworks (MOFs) as microporous electronic conductors is an exciting research frontier that has the potential to revolutionize a wide range of technologically and industrially relevant fields, from catalysis to solid-state sensing and energy-storage devices, among others. After nearly two decades of intense research on MOFs, examples of intrinsically conducting MOFs remain relatively scarce; however, enormous strides have recently been made. This article briefly reviews the current status of the field, with a focus on experimental milestones that have shed light on crucial structure–property relationships that underpin future progress. Central to our discussion are a series of design considerations, including redox-matching, donor–acceptor interactions, mixed valency, and π-interactions. Transformational opportunities exist at both fundamental and applied levels, from improved measurement techniques and theoretical understanding of conduction mechanisms to device engineering. Taken together, these developments will herald a new era in advanced functional materials.
The first Electrolyte-less dye sensitized solar cell (ELDSC) is proposed with the architecture of FTO-TiO2-dye-metal. In the ELDSC design, the most significant contact is the TiO2-dye-metal interface, whereby the metal electrode acts as the charge replenishment layer as well as the external electrode. In previous work, ELDSC has an inferior Fill Factor (FF) due to insufficient metal coverage from top-down physical vapor deposition. In this work, a three dimensional (3D) metal network plated through the mesoporous TiO2 network is achieved through bottom-up metal electroplating. This study focuses on the characteristics of electro deposition onto insulating planar TiO2 as well as mesoporous TiO2 network. For planar TiO2, gold (Au) islands form readily, becoming worm-like structures as they coalesce, subsequently becoming a continuous layer. (The plated metal on the insulating TiO2 layer is made possible by plane defects within the insulator layer that serve as the conductive supply path.) In contrast, electroplating carried out on a FTO-planar TiO2-mesoporous TiO2 substrate results in a 3D Au network within the mesoporous TiO2, where Au cords were observed as the connections among Au islands. This study demonstrates that a continuous metal layer can be electroplated onto an insulating TiO2 layer, borrowing its intrinsic planar defect network. Further, applying the same principle, a 3D metal network can be formed within mesoporous TiO2.
Research on the efficacy of sensory integration therapy (SIT) is addressed in this article. Initially, past key reviews of intervention studies until 1994 are considered. Subsequently, more recent studies from 1994 until 2007 are examined. Consistent with numerous previous reviews, no robust evidence supporting the efficacy of SIT was found. Alternative and more parsimonious explanations for purported effects of SIT are considered. In light of the accumulated lack of evidence for the effectiveness of SIT, continued use of the technique outside of research contexts does not appear to be justified.
Public participation in natural resource management has been described as paradoxical: citizens want the best science to guide natural resource management decisions, but not to the exclusion of their input; agencies want meaningful citizen involvement in their management decisions, but they also want citizens to trust their scientific expertise. As a result, many studies have focused on developing criteria for designing successful participatory processes. Rather than definitive guidelines, however, studies to date typically indicate broad rules of thumb, which may differ in situation-specific application depending on political and historical context. These observations suggest the need to identify contextual elements that influence the varying success of participatory process designs. One such element is the degree of understanding, or coorientation, between stakeholders and managers. This article expands the concept of coorientation to “coorientation contexts” to describe the real and/or incorrectly perceived barriers and opportunities for communication between natural resource managers and stakeholders. Examining participation philosophies and corresponding techniques reveals that certain types of communication are better suited to certain coorientation contexts. Tailoring participation strategies to the appropriate coorientation context throughout the evolution of public issues, i.e., “matching the forum to the fuss,” may ultimately result in more informed, equitable, and sustainable management decisions. Future empirical testing of this approach may improve natural resource managers' abilities to navigate successfully the paradox of public involvement in natural resource management.
With improvements in technology and surgical technique, paediatric cardiologists are challenging surgeons to repair balanced atrioventricular septal defects in smaller patients. Early repair minimizes aggressive medical therapy to prevent heart failure, maintains growth, and limits exposure to elevated pulmonary pressures. We compare the outcomes of repair among different-sized children.
From December 2002 to July 2005, 92 patients underwent repair of an atrioventricular septal defect with common atrioventricular valvar orifice and balanced ventricles. We reviewed operative and postoperative data. We excluded patients weighing more than 10 kilograms, but included those who underwent concomitant closure of a patent oval foramen or atrial septal defect, or ligation of a patent arterial duct. Those requiring other concomitant procedures were excluded from the analysis.
The median weight at repair was 4.9 kilograms, with a range from 2.93 to 7.9 kilograms, and the median age was 5.1 months, with a range from 0.39 to 9.6 months. Operative data included the time required for cardiopulmonary bypass, aortic cross-clamping, and the overall procedure. These times were not significantly affected by decreasing weight. Postoperative continuous data included duration of ventilation and length of intensive care unit and hospital stay. Stay in intensive care (p = 0.006) and hospital (p = 0.007) both increased significantly with decreasing weight. Postoperative categorical data included presence of residual ventricular septal defects, regurgitation across the left atrioventricular valve, and complications. While there was no difference in residual defects (p = 0.166) or valvar regurgitation (p = 0.729), there was a significantly higher presence of complications with decreasing weight (p = 0.0043). There was no mortality, and no persistent heart block requiring placement of a permanent pacemaker.
Our data shows that, with the exception of a slightly longer and more complicated postoperative course, early surgery for symptomatic patients with atrioventricular septal defects and common atrioventricular valvar orifice can be undertaken safely and effectively in smaller children with excellent outcomes.
Nasal bone fractures are the commonest type of bony facial injury causing aesthetic deformity. The aim of this study was to identify the effect of nasal trauma and fracture manipulation on the aesthetic proportions of the nose, by comparing pre- and post-treatment nasal aesthetics. Thirty-two patients (26 men and 6 women) underwent aesthetic assessment prior to treatment of the injury by closed nasal manipulation, 7 to 10 days after the initial injury. Standard facial aesthetic photographic assessments were performed prior to and following manipulation. Assessment involved measurement of standard nasal aesthetic parameters. In the nasal trauma cohort, the main anomalies in nasal aesthetics were nasal deviation and differences in the nasal aesthetic profile. Nasal fracture manipulation successfully reduced deviation from an average of 35° pre-manipulation to an average of 9° post-manipulation.
The aim of this study was to prospectively evaluate post-operative cessation of bleeding and late recurrence of epistaxis in a cohort of patients treated by endoscopic ligation of the sphenopalatine artery. Participants comprised patients undergoing sphenopalatine artery ligation for posterior epistaxis at three east Scotland hospitals. Main outcome measures were recurrence of epistaxis in the immediate post-operative period and at long-term follow up (minimum nine months). Forty-three patients (30 men and 13 women) underwent 45 procedures; two patients underwent bilateral ligation. Two patients suffered recurrence as in-patients. Two patients experienced subsequent epistaxis requiring medical treatment. Two further patients suffered minor late epistaxis not requiring treatment. Success in preventing significant recurrence was 93 per cent. All recurrences requiring intervention occurred within one month of surgery. None of the patients in this series reported nasal complications. We found sphenopalatine artery ligation to be an effective means of achieving long-term control of posterior epistaxis.
To assess the evidence surrounding the use of certain complementary supplements in otolaryngology. We specifically focussed on four commonly used supplements: spirulina, Ginkgo biloba, Vertigoheel® and nutritional supplements (cod liver oil, multivitamins and pineapple enzyme).
Materials and methods:
A systematic review of the English and foreign language literature. Inclusion criteria: in vivo human studies. Exclusion criteria: animal trials, in vitro studies and case reports. We also excluded other forms of ‘alternative medicine’ such as reflexology, acupuncture and other homeopathic remedies.
Lack of common outcome measures prevented a formal meta-analysis. Three studies on the effects of spirulina in allergy, rhinitis and immunomodulation were found. One was a double-blind, placebo, randomised, controlled trial (RCT) of patients with allergic rhinitis, demonstrating positive effects in patients fed spirulina for 12 weeks. The other two studies, although non-randomised, also reported a positive role for spirulina in mucosal immunity. Regarding the use of Ginkgo biloba in tinnitus, a Cochrane review published in 2004 showed no evidence for this. The one double-blind, placebo-controlled trial that followed confirmed this finding. Regarding the use of Vertigoheel in vertigo, two double-blind RCTs and a meta-analysis were identified. The first RCT suggested that Vertigoheel was equally effective in reducing the severity, duration and frequency of vertigo compared with betahistine. The second RCT suggested that Vertigoheel was a suitable alternative to G biloba in the treatment of atherosclerosis-related vertigo. A meta-analysis of only four clinical trials confirms that Vertigoheel was equally effective compared with betahistine, G biloba and dimenhydrinate. Regarding multivitamins and sinusitis, two small paediatric pilot studies reported a positive response for chronic sinusitis and otitis media following a course of multivitamins and cod liver oil. Regarding bromelain (pineapple enzyme) and sinusitis, one randomised, multicentre trial including 116 children compared bromelain monotherapy to bromelain with standard therapy and standard therapy alone, for the treatment of acute sinusitis. The bromelain monotherapy group showed a faster recovery compared with the other groups.
The positive effects of spirulina in allergic rhinitis and of Vertigoheel in vertigo are based on good levels of evidence, but larger trials are required. There is overwhelming evidence that G biloba may play no role in tinnitus. There is limited evidence for the use of multivitamins in sinus symptoms, and larger randomised trials are required.
Tantalum oxide has attracted world-wide interest for DRAM (dynamic random access memory) capacitor applications because of its relative high dielectric constant compared to silicon dioxide or nitride. We would like to point out that tantalum oxide behaves very much like a large bandgap n-type semiconductor with 3 main types of donors responsible for leakage current. Native oxygen vacancies are very deep double donors with Ec – Ed = 0.8 eV approximately, where Ec is the bottom of the conduction band and Ed is the energy leVel of the defect state. Si-O vacancy complexes are relatively shallow single donors with Ec – Ed = 0.2-0.4 eV. C-O vacancy complexes are relatively shallow single donors with Ec – Ed = 0.5-0.6 eV. The key points regarding how to suppress these 3 types of donor defects will be discussed for the purpose of leakage current reduction.
The artistlike pictures of vortex flows presented here have been produced by the flow itself. The method of this “natural” flow visualization can be described briefly as follows: The working fluid is water mixed with some paste in order to increase the viscosity. Vortex flows are produced by pulling a stick or similar devices through the fluid or by injecting fluid through a nozzle into the working tank.
The flow visualization is performed in the following way: the surface of the fluid at rest is sparkled with oil paint of different colors diluted with some evaporating chemical. After the vortex structures have formed due to wakes or jets, a sheet of white paper is placed on the surface of the working fluid, where the oil color is attached to the paper immediately. The final results are artistlike paintings of vortex flows which exhibit a rich variety of flow structures.
Mixing in regular and chaotic flows
These photographs show the time evolution of two passive tracers in a low Reynolds number two-dimensional timeperiodic flow. The initial condition corresponds to two blobs of dye, green and orange, located below the free surface of a cavity filled with glycerine. The flow is induced by moving the top and bottom walls of the cavity while the other two walls are fixed. In this experiment the top wall moves from left to right and the bottom wall moves from right to left; both velocities are of the form Usin2(2πt/T), with the same U and the same period T, but with a phase shift of 90°.