Peristaltic transport of bi-viscosity fluids through a curved tube : a mathematical model for intestinal flow

The human intestinal tract is a long curved tube constituting the final section of the digestive system in which nutrients and water are mostly absorbed. Motivated by the dynamics of chyme in the intestine, a mathematical model is developed to simulate the associated transport phenomena via peristaltic transport. Rheology of chyme is modelled using the Nakamura-Sawada bi-viscosity non-Newtonian formulation. The intestinal tract is considered as a curved tube geometric model. Low Reynolds number (creeping hydrodynamics) and long wavelength approximations are taken into consideration.Analytical solutions of the moving boundary value problem are derived for velocity field,pressure gradient and pressure rise. Streamline flow visualization is achieved with Mathematica symbolic software. Peristaltic pumping phenomenon and trapping of the bolus are also examined. The influence of curvature parameter, apparent viscosity coefficient (rheological parameter) and volumetric flow rate on flow characteristics is described. Validation of analytical solutions is achieved with a MAPLE17 numerical quadrature algorithm. The work is relevant to improving understanding of gastric hydrodynamics and provides a benchmark for further computational fluid dynamics (CFD) simulations

Mathematical model for ciliary-induced transport in MHD flow of Cu-H2O nanoßuids with magnetic induction

Motivated by novel developments in surface-modified, nanoscale, magnetohydrodynamic (MHD) biomedical devices, we study theoretically the ciliary induced transport by metachronal wave propagation in hydromagnetic flow of copper-water nanofluids through a parallel plate channel. Under the physiological constraints, creeping flow is taken into consideration i.e. inertial forces are small compared with viscous forces. The metachronal wavelength is also considered as very large for cilia induced MHD flow. Magnetic Reynolds number is sufficiently large to invoke magnetic induction effects. The physical problem is linearized and exact solutions are developed for the resulting boundary value problem. Closed-form expressions are presented for the stream function, pressure rise, induced magnetic field function and temperature. Mathematica symbolic software is used to compute and illustrate numerical results. The influence of physical parameters on velocity profile, pressure gradient and trapping of bolus are discussed with the aid of graphs. The present computations are applicable to simulations of flow control of in nano-magneto-biomimetic technologies

The validity and reliability of observational assessment tools available to measure fundamental movement skills in school-age children: A systematic review

Background Fundamental Movement Skills (FMS) play a critical role in ontogenesis. Many children have insufficient FMS, highlighting the need for universal screening in schools. There are many observational FMS assessment tools, but their psychometric properties are not readily accessible. A systematic review was therefore undertaken to compile evidence of the validity and reliability of observational FMS assessments, to evaluate their suitability for screening. Methods A pre-search of ‘fundamental movement skills’ OR ‘fundamental motor skills’ in seven online databases (PubMed, Ovid MEDLINE, Ovid Embase, EBSCO CINAHL, EBSCO SPORTDiscus, Ovid PsycINFO and Web of Science) identified 24 assessment tools for school-aged children that: (i) assess FMS; (ii) measure actual motor competence and (iii) evaluate performance on a standard battery of tasks. Studies were subsequently identified that: (a) used these tools; (b) quantified validity or reliability and (c) sampled school-aged children. Study quality was assessed using COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklists. Results Ninety studies were included following the screening of 1863 articles. Twenty-one assessment tools had limited or no evidence to support their psychometric properties. The Test of Gross Motor Development (TGMD, n = 34) and the Movement Assessment Battery for Children (MABC, n = 37) were the most researched tools. Studies consistently reported good evidence for validity, reliability for the TGMD, whilst only 64% of studies reported similarly promising results for the MABC. Twelve studies found good evidence for the reliability and validity of the Bruininks-Oseretsky Test of Motor Proficiency but poor study quality appeared to inflate results. Considering all assessment tools, those with promising psychometric properties often measured limited aspects of validity/reliability, and/or had limited feasibility for large scale deployment in a school-setting. Conclusion There is insufficient evidence to justify the use of any observational FMS assessment tools for universal screening in schools, in their current form

Effects of membrane curvature and pH on proton pumping activity of single cytochrome bo3 enzymes

The molecular mechanism of proton pumping by heme-copper oxidases (HCO) has intrigued the scientific community since it was first proposed. We have recently reported a novel technology that enables the continuous characterisation of proton transport activity of a HCO and ubiquinol oxidase from Escherichia coli, cytochrome bo3, for hundreds of seconds on the single enzyme level (Li et al. J Am Chem Soc 137 (2015) 16055–16063). Here, we have extended these studies by additional experiments and analyses of the proton transfer rate as a function of proteoliposome size and pH at the N- and P-side of single HCOs. Proton transport activity of cytochrome bo3 was found to decrease with increased curvature of the membrane. Furthermore, proton uptake at the N-side (proton entrance) was insensitive to pH between pH 6.4–8.4, while proton release at the P-side had an optimum pH of 7.4, suggesting that the pH optimum is related to proton release from the proton exit site. Our previous single-enzyme experiments identified rare, long-lived conformation states of cytochrome bo3 where protons leak back under turn-over conditions. Here, we analyzed and found that 23% of cytochrome bo3 proteoliposomes show ΔpH half-lives below 50 s after stopping turnover, while only 5% of the proteoliposomes containing a non-pumping mutant, E286C cytochrome bo3 exhibit such fast decays. These single-enzyme results confirm our model in which HCO exhibit heterogeneous pumping rates and can adopt rare leak states in which protons are able to rapidly flow back

Three-dimensional visualization software assists learning in students with diverse spatial intelligence in medical education

This study evaluated effect of mental rotation (MR) training on learning outcomes and explored effectiveness of teaching via three-dimensional (3D) software among medical students with diverse spatial intelligence. Data from n = 67 student volunteers were included. A preliminary test was conducted to obtain baseline level of MR competency and was utilized to assign participants to two experimental conditions, i.e., trained group (n = 25) and untrained group (n = 42). Data on the effectiveness of training were collected to measure participants\u27 speed and accuracy in performing various MR activities. Six weeks later, a large class format (LCF) session was conducted for all students using 3D software. The usefulness of technology-assisted learning at the LCF was evaluated via a pre- and post-test. Students\u27 feedback regarding MR training and use of 3D software was acquired through questionnaires. MR scores of the trainees improved from 25.9±4.6 points to 28.1±4.4 (P = 0.011) while time taken to complete the tasks reduced from 20.9±3.9 to 12.2±4.4 minutes. Males scored higher than females in all components (P = 0.016). Further, higher pre- and post-test scores were observed in trained (9.0±1.9 and 12.3±1.6) versus untrained group (7.8±1.8; 10.8±1.8). Although mixed-design analysis of variance suggested significant difference in their test scores (P \u3c 0.001), both groups reported similar trend in improvement by means of 3D software (P = 0.54). Ninety-seven percent of students reported technology-assisted learning as an effective means of instruction and found use of 3D software superior to plastic models. Software based on 3D technologies could be adopted as an effective teaching pedagogy to support learning across students with diverse levels of mental rotation abilities

Survival and health economic outcomes in heart failure diagnosed at hospital admission versus community settings: a propensity-matched analysis

BACKGROUND AND AIMS: Most patients with heart failure (HF) are diagnosed following a hospital admission. The clinical and health economic impacts of index HF diagnosis made on admission to hospital versus community settings are not known. METHODS: We used the North West London Discover database to examine 34 208 patients receiving an index diagnosis of HF between January 2015 and December 2020. A propensity score-matched (PSM) cohort was identified to adjust for differences in socioeconomic status, cardiovascular risk and pre-diagnosis health resource utilisation cost. Outcomes were stratified by two pathways to index HF diagnosis: a 'hospital pathway' was defined by diagnosis following hospital admission; and a 'community pathway' by diagnosis via a general practitioner or outpatient services. The primary clinical and health economic endpoints were all-cause mortality and cost-consequence differential, respectively. RESULTS: The diagnosis of HF was via hospital pathway in 68% (23 273) of patients. The PSM cohort included 17 174 patients (8582 per group) and was matched across all selected confounders (p>0.05). The ratio of deaths per person-months at 24 months comparing community versus hospital diagnosis was 0.780 (95% CI 0.722 to 0.841, p<0.0001). By 72 months, the ratio of deaths was 0.960 (0.905 to 1.020, p=0.18). Diagnosis via hospital pathway incurred an overall extra longitudinal cost of £2485 per patient. CONCLUSIONS: Index diagnosis of HF through hospital admission continues to dominate and is associated with a significantly greater short-term risk of mortality and substantially increased long-term costs than if first diagnosed in the community. This study highlights the potential for community diagnosis-early, before symptoms necessitate hospitalisation-to improve both clinical and health economic outcomes

Underweight and overweight men have greater exercise-induced dyspnoea than normal weight men.

INTRODUCTION: Persons with high or low body mass index (BMI), involved in clinical or mechanistic trials involving exercise testing, might estimate dyspnoea differently from persons with a normal BMI. AIMS: Our objective was to investigate the relationship between BMI and dyspnoea during exercise in normal subjects with varying BMI. MATERIAL AND METHODS: A total of 37 subjects undertook progressive exercise testing. Subjects were divided into three groups: underweight (UW), normal weight (NW), and overweight (OW). Dyspnoea was estimated using the visual analogue scale (VAS). Spirometry, maximum voluntary ventilation (MVV), and respiratory muscle strength (RMS) were measured. RESULTS AND DISCUSSION: The intercept of the VAS/ventilation relationship was significantly higher in NW subjects compared to UW (P = 0.029) and OW subjects (P = 0.040). Relative to the OW group, FVC (P = 0.020), FEV(1) (P = 0.024), MVV (P = 0.019), and RMS (P = 0.003) were significantly decreased in the UW group. The greater levels of dyspnoea in UW subjects could possibly be due to decreased RMS. Healthy persons should aim to achieve an optimum BMI range to have the lowest exercise-induced dyspnoea

Rising burden of Hepatitis C Virus in hemodialysis patients

<p>Abstract</p> <p>Aim</p> <p>High prevalence of Hepatitis C virus (HCV) has been reported among the dialysis patients throughout the world. No serious efforts were taken to investigate HCV in patients undergoing hemodialysis (HD) treatment who are at great increased risk to HCV. HCV genotypes are important in the study of epidemiology, pathogenesis and reaction to antiviral therapy. This study was performed to investigate the prevalence of active HCV infection, HCV genotypes and to assess risk factors associated with HCV genotype infection in HD patients of Khyber Pakhtunkhwa as well as comparing this prevalence data with past studies in Pakistan.</p> <p>Methods</p> <p>Polymerase chain reaction was performed for HCV RNA detection and genotyping in 384 HD patients. The data obtained was compared with available past studies from Pakistan.</p> <p>Results</p> <p>Anti HCV antibodies were observed in 112 (29.2%), of whom 90 (80.4%) were HCV RNA positive. In rest of the anti HCV negative patients, HCV RNA was detected in 16 (5.9%) patients. The dominant HCV genotypes in HCV infected HD patients were found to be 3a (n = 36), 3b (n = 20), 1a (n = 16), 2a (n = 10), 2b (n = 2), 1b (n = 4), 4a (n = 2), untypeable (n = 10) and mixed (n = 12) genotype.</p> <p>Conclusion</p> <p>This study suggesting that i) the prevalence of HCV does not differentiate between past and present infection and continued to be elevated ii) HD patients may be a risk for HCV due to the involvement of multiple routes of infections especially poor blood screening of transfused blood and low standard of dialysis procedures in Pakistan and iii) need to apply infection control practice.</p