Immersed boundary method combined with proper generalized decomposition for simulation of a flexible filament in a viscous incompressible flow

In this paper, a combination of the Proper Generalized  Decomposition (PGD) with the Immersed Boundary method (IBM) for solving  fluid-filament interaction problem is proposed. In this combination, a  forcing term constructed by the IBM is introduced to Navier-Stokes equations  to handle the influence of the filament on the fluid flow. The PGD is  applied to solve the Poission's equation to find the fluid pressure  distribution for each time step. The numerical results are compared with  those by previous publications to illustrate the robustness and  effectiveness of the proposed method

Viral pathogens associated with acute respiratory infections in central vietnamese children.

Hospitalized Vietnamese children with acute respiratory infection were investigated for 13 viral pathogens using multiplex-polymerase chain reaction. We enrolled 958 children of whom 659 (69%) had documented viral infection: rhinovirus (28%), respiratory syncytial virus (23%), influenza virus (15%), adenovirus (5%), human metapneumo virus (4.5%), parainfluenza virus (5%), and bocavirus (2%). These Vietnamese children had a range of respiratory viruses which underscores the need for enhanced acute respiratory infection surveillance in tropical developing countries

Mothers screening for malnutrition by mid-upper arm circumference is non-inferior to community health workers: results from a large-scale pragmatic trial in rural Niger

Community health workers (CHWs) are recommended to screen for acute malnutrition in the community by assessing mid-upper arm circumference (MUAC) on children between 6 and 59 months of age. MUAC is a simple screening tool that has been shown to be a better predictor of mortality in acutely malnourished children than other practicable anthropometric indicators. This study compared, under program conditions, mothers and CHWs in screening for severe acute malnutrition (SAM) by color-banded MUAC tapes. METHODS: This pragmatic interventional, non-randomized efficacy study took place in two health zones of Niger's Mirriah District from May 2013 to April 2014. Mothers in Dogo (Mothers Zone) and CHWs in Takieta (CHWs Zone) were trained to screen for malnutrition by MUAC color-coded class and check for edema. Exhaustive coverage surveys were conducted quarterly, and relevant data collected routinely in the health and nutrition program. An efficacy and cost analysis of each screening strategy was performed. RESULTS: A total of 12,893 mothers and caretakers were trained in the Mothers Zone and 36 CHWs in the CHWs Zone, and point coverage was similar in both zones at the end of the study (35.14 % Mothers Zone vs 32.35 % CHWs Zone, p = 0.9484). In the Mothers Zone, there was a higher rate of MUAC agreement (75.4 % vs 40.1 %, p <0.0001) and earlier detection of cases, with median MUAC at admission for those enrolled by MUAC <115 mm estimated to be 1.6 mm higher using a smoothed bootstrap procedure. Children in the Mothers Zone were much less likely to require inpatient care, both at admission and during treatment, with the most pronounced difference at admission for those enrolled by MUAC < 115 mm (risk ratio = 0.09 [95 % CI 0.03; 0.25], p < 0.0001). Training mothers required higher up-front costs, but overall costs for the year were much lower ($8,600 USD vs$21,980 USD.). CONCLUSIONS: Mothers were not inferior to CHWs in screening for malnutrition at a substantially lower cost. Children in the Mothers Zone were admitted at an earlier stage of SAM and required fewer hospitalizations. Making mothers the focal point of screening strategies should be included in malnutrition treatment programs.BioMed Central open acces

Obscured Activity: AGN, Quasars, Starbursts and ULIGs observed by the Infrared Space Observatory

Some of the most active galaxies in the Universe are obscured by large quantities of dust and emit a substantial fraction of their bolometric luminosity in the infrared. Observations of these infrared luminous galaxies with the Infrared Space Observatory (ISO) have provided a relatively unabsorbed view to the sources fuelling this active emission. The improved sensitivity, spatial resolution and spectroscopic capability of ISO over its predecessor Infrared Astronomical Satellite (IRAS), has enabled significant advances in the understanding of the infrared properties of active galaxies. ISO surveyed a wide range of active galaxies which, in the context of this review, includes those powered by intense bursts of star-formation as well as those containing a dominant active galactic nucleus (AGN). Mid infrared imaging resolved for the first time the dust enshrouded nuclei in many nearby galaxies, while a new era in infrared spectroscopy was opened by probing a wealth of atomic, ionic and molecular lines as well as broad band features in the mid and far infrared. This was particularly useful since it resulted in the understanding of the power production, excitation and fuelling mechanisms in the nuclei of active galaxies including the intriguing but so far elusive ultraluminous infrared galaxies. Detailed studies of various classes of AGN and quasars greatly improved our understanding of the unification scenario. Far-infrared imaging and photometry also revealed the presence of a new very cold dust component in galaxies and furthered our knowledge of the far-infrared properties of faint starbursts, ULIGs and quasars. We summarise almost nine years of key results based upon ISO data spanning the full range of luminosity and type of active galaxies.Comment: Accepted for publication in 'ISO science legacy - a compact review of ISO major achievements', Space Science Reviews - dedicated ISO issue. To be published by Springer in 2005. 62 pages (low resolution figures version). Higher resolution PDFs available from http://users.physics.uoc.gr/~vassilis/papers/VermaA.pdf or http://www.iso.vilspa.esa.es/science/SSR/Verma.pd

A mechanically active heterotypic E-cadherin/N-cadherin adhesion enables fibroblasts to drive cancer cell invasion

Cancer-associated fibroblasts (CAFs) promote tumour invasion and metastasis. We show that CAFs exert a physical force on cancer cells that enables their collective invasion. Force transmission is mediated by a heterophilic adhesion involving N-cadherin at the CAF membrane and E-cadherin at the cancer cell membrane. This adhesion is mechanically active; when subjected to force it triggers β-catenin recruitment and adhesion reinforcement dependent on α-catenin/vinculin interaction. Impairment of E-cadherin/N-cadherin adhesion abrogates the ability of CAFs to guide collective cell migration and blocks cancer cell invasion. N-cadherin also mediates repolarization of the CAFs away from the cancer cells. In parallel, nectins and afadin are recruited to the cancer cell/CAF interface and CAF repolarization is afadin dependent. Heterotypic junctions between CAFs and cancer cells are observed in patient-derived material. Together, our findings show that a mechanically active heterophilic adhesion between CAFs and cancer cells enables cooperative tumour invasion

Search for the direct production of charginos and neutralinos in final states with tau leptons in √s=13 TeV collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with at least two hadronically decaying tau leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of 36.1 fb−1, recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13TeV.Nosignificant deviation from the expected Standard Model background is observed. Limits are derived in scenarios of ˜χ+1 ˜χ−1 pair production and of ˜χ±1 ˜χ02 and ˜χ+1 ˜χ−1 production in simplified models where the neutralinos and charginos decay solely via intermediate left-handed staus and tau sneutrinos, and the mass of the ˜ τL state is set to be halfway between the masses of the ˜χ±1 and the ˜χ01. Chargino masses up to 630 GeV are excluded at 95% confidence level in the scenario of direct production of ˜χ+1 ˜χ−1 for a massless ˜χ01. Common ˜χ±1 and ˜χ02 masses up to 760 GeV are excluded in the case of production of ˜χ±1 ˜χ02 and ˜χ+1 ˜χ−1 assuming a massless ˜χ01. Exclusion limits for additional benchmark scenarios with large and small mass-splitting between the ˜χ±1 and the ˜χ01 are also studied by varying the ˜ τL mass between the masses of the ˜χ±1 and the ˜χ01

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

The exertion of cell-cell adhesions

Regulation of cadherin adhesion in tissue organization and malignant transformation.Cadherins are cell-cell adhesion molecules present in all tissues. Cadherins are transmembrane-proteins that form a homotypic, calcium-dependent complex with cadherins molecules onneighboring cells 1. Inside the cell, they connect to the actin cytoskeleton2 and thus mediate astrong physical connection between cells. As such, cadherins are important in the control of a widerange of fundamental biological processes, including embryonic development, tissuemorphogenesis and vascular homeostasis. The main epithelial cadherin, E-cadherin, organizes intocell-cell adhesion structures called Adherens Junctions (AJ)3 and is a tumor suppressor4, whose lossof expression, mainly through gene-silencing, results in tumor metastasis5-7. However, several typesof metastatic cancer, like certain agressive breast carcinomas (reviewed in8-10), do not show anydownregulation of the E-cadherin protein. This implies that alternative mechanisms must exist to(de-) regulate E-cadherin adhesion.At the start of the research described in this thesis, several reports had shown that cytoskeletaltension is involved in the downregulation of AJs. Tumor tissue was found to be stiffer than normaltissue and artificial increase of tissue stiffness in breast cancer cells resulted in the disorganizationof AJs11. It was shown in our lab, that HGF-induced scattering of epithelial MDCK cells depends onactomyosin-driven cytoskeletal tension12: Myosin activity increased after HGF; the structure of thecytoskeleton changed after HGF; Actin-bundles were formed that connected to cell-cell junctionsto pull them apart; inhibitors of myosin activity prevented all of this from happening. Togetherthese observations indicated that E-cadherin’s adhesive function is sensitive to cytoskeletaltension, but the underlying mechanisms remained completely elusive. The dynamic link between E-cadherin and actin. It had been generally accepted, through a large number of experimental studies, that E-cadherininteracts with actin through catenin and the actin-binding protein catenin. A number of otherproteins had been found associated with the E-cadherin complex, including most notably p120-catenin, actinin and vinculin. P120-catenin was known to regulate E-cadherin’s stability13, 14. Thefunction of actinin and vinculin, two proteins that are also present in integrin-based adhesions,was less clear15.In the year before this PhD research started, this established view on the linkage between E-cadherin and the cytoskeleton had been challenged in two recent papers from James Nelson andWilliam Weis16, 17. They showed that a ternary complex of E-cadherin, -catenin and actin cannot form in vitro. Furthermore, they showed that catenin cannot interact with actin and cateninsimultaneously: It interacts with catenin as a monomer that posesses low affinity for F-actin.Dimerization, which is needed for high affinity for F-actin, excludes the interaction with catenin.This discrepancy between old models and the new observations, and the importance of cadherinadhesion for tissue development and cancer, triggered a lot of new research into the linkagebetween E-cadherin and the actin cytoskeleton.The emerging role of mechanical forces in cadherin adhesionThe one crucial factor that the Nelson/Weis studies did not address was the role of mechanicalforces. From integrin-adhesion research it was known that tension on integrin adhesions, causedby contractility in the associated actomyosin cytoskeleton, is needed for their development fromnascent to mature18. Furthermore, our data and that of others had just indicated that myosinactivity is needed for the formation of stable cadherin adhesions12. The research described in thisthesis was aimed at further elucidating the molecular details of the link between cadherins and theactomyosin cytoskeleton in order to understand how mechanical tension influences the dynamicsand function of cadherin adhesion