A squirmer across Reynolds numbers

The self-propulsion of a spherical squirmer – a model swimming organism that achieves locomotion via steady tangential movement of its surface – is quantified across the transition from viscously to inertially dominated flow. Specifically, the flow around a squirmer is computed for Reynolds numbers ($Re$) between 0.01 and 1000 by numerical solution of the Navier–Stokes equations. A squirmer with a fixed swimming stroke and fixed swimming direction is considered. We find that fluid inertia leads to profound differences in the locomotion of pusher (propelled from the rear) versus puller (propelled from the front) squirmers. Specifically, pushers have a swimming speed that increases monotonically with $Re$, and efficient convection of vorticity past their surface leads to steady axisymmetric flow that remains stable up to at least $Re=1000$. In contrast, pullers have a swimming speed that is non-monotonic with $Re$. Moreover, they trap vorticity within their wake, which leads to flow instabilities that cause a decrease in the time-averaged swimming speed at large $Re$. The power expenditure and swimming efficiency are also computed. We show that pushers are more efficient at large $Re$, mainly because the flow around them can remain stable to much greater $Re$ than is the case for pullers. Interestingly, if unstable axisymmetric flows at large $Re$ are considered, pullers are more efficient due to the development of a Hill’s vortex-like wake structure.This work was funded in part by the European Union through a CIG grant to EL. NGC acknowledges partial support from the John and Claire Bertucci Fellowship in Engineering.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by Cambridge University Press

A model for the fluid dynamic behavior of a film coating suspension during tablet coating

This work models the behavior of a liquid-particle suspension on the surface of a tablet during the pharmaceutical film-coating process. The model uses the “mixture modeling” approach and the lubrication approximation method to simulate how the suspension moves and dries on the surface of a tablet, considering how important physical properties of the suspension, such as the density and viscosity, change when the carrier fluid evaporates.The model also accounts for the absorption of the coating suspension inside the core of the porous tablet, yielding the tablet water content, a key quantity characterizing the coating process. The numerical results, obtained with the gPROMS Modelbuilder platform, agree with experimental data taken from the literature and Volume-Of-Fluid CFD simulations

Molecular analysis demonstrates high prevalence of chloroquine resistance but no evidence of artemisinin resistance in Plasmodium falciparum in the Chittagong Hill Tracts of Bangladesh

Background Artemisinin resistance is present in the Greater Mekong region and poses a significant threat for current anti-malarial treatment guidelines in Bangladesh. The aim of this molecular study was to assess the current status of drug resistance in the Chittagong Hill Tracts of Bangladesh near the Myanmar border. Methods Samples were obtained from patients enrolled into a Clinical Trial (NCT02389374) conducted in Alikadam, Bandarban between August 2014 and January 2015. Plasmodium falciparum infections were confirmed by PCR and all P. falciparum positive isolates genotyped for the pfcrt K76T and pfmdr1 N86Y markers. The propeller region of the kelch 13 (k13) gene was sequenced from isolates from patients with delayed parasite clearance. Results In total, 130 P. falciparum isolates were available for analysis. The pfcrt mutation K76T, associated with chloroquine resistance was found in 81.5% (106/130) of cases and the pfmdr1 mutation N86Y in 13.9% (18/130) cases. No single nucleotide polymorphisms were observed in the k13 propeller region. Conclusion This study provides molecular evidence for the ongoing presence of chloroquine resistant P. falciparum in Bangladesh, but no evidence of mutations in the k13 propeller domain associated with artemisinin resistance. Monitoring for artemisinin susceptibility in Bangladesh is needed to ensure early detection and containment emerging anti-malarial resistance.</p

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

Relasi Iman dan Kesehatan Mental Perspektif Psikologi Agama

Tantangan globalisasi dan modernisasi dewasa ini membawa ekses yang nyata terhadap orientasi iman dan perilaku beragama yang dianut oleh seseorang, ada yang mengarah pada ekses positif dan ada yang negatif. Dua orientasi sikap beragama kemudian juga berimplikasi pada status kesehatan mental masing-masing pemeluk agama, apakah mengarah pada mental yang sehat atau sebaliknya. Kajian ini menggunakan perspektif psikologi agama milik Gordon Allport, di mana merupakan suatu pendekatan yang dipilih untuk melihat protret penghayatan keberagaman individu, pengalaman-pengalaman yang dirasakan, dan implikasinya bagi kesehatan mental. Orientasi keberimanan dan perilaku religius seseorang pada satu sisi menitikberatkan pada komitmen menghayati dan menjalankan agama secara utuh (kaffah), tidak dogmatis, tidak egoistis, dinamis, dan berimplikasi positif bagi kesehatan mental. Orientasi religius yang seperti ini, seringkali dikategorisasikan sebagai orientasi religius yang bersifat intrinsik. Pada sisi lain, ada yang menekankan keberagamaannya pada hal-hal yang bersifat dogmatis, egoistis, motif pribadi, adanya prasangka, dan berimplikasi negatif bagi kesehatan mental. Inilah yang dikategorisasikan dengan orientasi religius yang bersifat ekstrinsik. Dalam konteks ini, pilihan orientasi beragama, akan menentukan status kesehatan mental pada setiap pemeluk agama