Universality of Local Dissipation Scales in Turbulent Boundary Layer Flows With and Without Free-Stream Turbulence

Measurements of the small-scale dissipation statistics of turbulent boundary layer flows with and without free-stream turbulence are reported for Reτ ≈ 1000 (Reθ ≈ 2000). The scaling of the dissipation scale distribution is examined in these two boundary conditions. Results demonstrated that the local large-scale Reynolds number based on the measured longitudinal integral length scale fails to properly normalize the dissipation scale distribution near the wall in these two free-stream conditions due to the imperfect characterization of the upper bound of the inertial cascade by the integral length scale. A surrogate found from turbulent kinetic energy and mean dissipation rate only moderately improved the scaling of the dissipation scales, relative to the measured integral length scale. When a length scale based on the distance from the wall [as suggested by Bailey and Witte, “On the universality of local dissipation scales in turbulent channel flow,” J. Fluid Mech. 786, 234–252 (2015)] was utilized to scale the dissipation scale distribution, in the region near the wall, there was a noticeable improvement in the collapse of the normalized distribution of dissipation scales. In addition, unlike in channel flows, in the outer layer of the turbulent boundary layer, the normalized distributions of the local dissipation scales were observed to be dependent on the wall-normal position. This was found to be attributable to the presence of external intermittency in the outer layer as the presence of free-stream turbulence was found to restore the scaling behavior by replacing the intermittent laminar flow with turbulent flow

Graphene-based wideband metamaterial absorber for solar cells application

A wideband metamaterial (MTM) absorber based on a concentric ring resonator is discussed at visible frequencies. The proposed structure offers a wideband absorption response, where absorption of >70% is gained for the frequency ranging from 537.91 to 635.73 THz. The analysis is conducted on the components of the proposed structure to understand the origin of wideband absorption. Furthermore, a graphene monolayer sheet is integrated to the proposed MTM absorber to optimize its absorptivity, where the studies show enhancement of the absorptivity of the proposed structure up to 26% from its initial absorptivity. MTM absorbers of this kind have potential applications in solar cells. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE

Effect of the Metallization on the Resonances of THz Fishnet Metamaterials

In this numerical study, the influence of the choice of metal (and hence of the conductivity) used for the fabrication of THz fishnet metamaterials is investigated. We explore an exemplary structure for which surface-plasmon-polaritons offer – assuming sufficiently good conductivity – pronounced extraordinary transmission and strong multiple magnetic resonances with negative permeability. We analyze the dependence of these signatures on the type of metallization. Studying five different metals, we find that the metallization is important for achieving the multiple resonances. A reduction of the conductivity can lead to a dramatic weakening and even a near-disappearance of magnetic resonances if they lose their diamagnetic character

Improving timeliness for acute asthma care for paediatric ED patients using a nurse driven intervention: an interrupted time series analysis.

Asthma is the most common chronic paediatric disease treated in the emergency department (ED). Rapid corticosteroid administration is associated with improved outcomes, but our busy ED setting has made it challenging to achieve this goal. Our primary aim was to decrease the time to corticosteroid administration in a large, academic paediatric ED. We conducted an interrupted time series analysis for moderate to severe asthma exacerbations of one to 18 year old patients. A multidisciplinary team designed the intervention of a bedside nurse initiated administration of oral dexamethasone, to replace the prior system of a physician initiated order for oral prednisone. Our baseline and intervention periods were 12 month intervals. Our primary process measure was the time to corticosteroid administration. Other process measures included ED length of stay, admission rate, and rate of emesis. The balance measures included rate of return visits to the ED or clinic within five days, as well as the proportion of discharged patients who were admitted within five days. No special cause variation occurred in the baseline period. The mean time to corticosteroid administration decreased significantly, from 98 minutes in the baseline period to 59 minutes in the intervention period (p \u3c 0.01), and showed special cause variation improvement within two months after the intervention using statistical process control methodology. We sustained the improvement and demonstrated a stable process. The intervention period had a significantly lower admission rate (p\u3c0.01) and emesis rate (p\u3c0.01), with no unforeseen harm to patients found with any of our balance measures. In summary, the introduction of a nurse initiated, standardized protocol for corticosteroid therapy for asthma exacerbations in a paediatric ED was associated with decreased time to corticosteroid administration, admission rates, and post-corticosteroid emesi

The GIP receptor displays higher basal activity than the GLP-1 receptor but does not recruit GRK2 or arrestin3 effectively.

Background and Objectives: Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are important regulators of insulin secretion, and their functional loss is an early characteristic of type 2 diabetes mellitus (T2DM). Pharmacological levels of GLP-1, but not GIP, can overcome this loss. GLP-1 and GIP exert their insulinotropic effects through their respective receptors expressed on pancreatic β-cells. Both the GLP-1 receptor (GLP-1R) and the GIP receptor (GIPR) are members of the secretin family of G protein-coupled receptors (GPCRs) and couple positively to adenylate cyclase. We compared the signalling properties of these two receptors to gain further insight into why GLP-1, but not GIP, remains insulinotropic in T2DM patients. Methods: GLP-1R and GIPR were transiently expressed in HEK-293 cells, and basal and ligand-induced cAMP production were investigated using a cAMP-responsive luciferase reporter gene assay. Arrestin3 (Arr3) recruitment to the two receptors was investigated using enzyme fragment complementation, confocal microscopy and fluorescence resonance energy transfer (FRET). Results: GIPR displayed significantly higher (P<0.05) ligand-independent activity than GLP-1R. Arr3 displayed a robust translocation to agonist-stimulated GLP-1R but not to GIPR. These observations were confirmed in FRET experiments, in which GLP-1 stimulated the recruitment of both GPCR kinase 2 (GRK2) and Arr3 to GLP-1R. These interactions were not reversed upon agonist washout. In contrast, GIP did not stimulate recruitment of either GRK2 or Arr3 to its receptor. Interestingly, arrestin remained at the plasma membrane even after prolonged (30 min) stimulation with GLP-1. Although the GLP-1R/arrestin interaction could not be reversed by agonist washout, GLP-1R and arrestin did not co-internalise, suggesting that GLP-1R is a class A receptor with regard to arrestin binding. Conclusions:: GIPR displays higher basal activity than GLP-1R but does not effectively recruit GRK2 or Arr3

Transmission measurements of a new metamaterial sample with negative refraction index

We presented the microwave experiments with a new metamaterial composed of triangular split ring resonators (TSRRs) and wire strip at microwave regime. The transmission measurements were performed in free space for two LHM samples which have different number of TSRRs and wire strips. The experimental results show that the left-handed transmission peak stands in the frequency band where both the permittivity and permeability are negative. It is also observed that left-handed transmission band can be shifted if the number of TSRRs and wire strips are changed. Crown Copyright © 2010 Published by Elsevier B.V. All rights reserved

Mapping of DBLα Sequence Tags of Field Isolates from Two Malaria Endemic Sites in Kenya

Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) found on the surface of infected erythrocytes (IEs) mediate antigenic variation during P. falciparum infection enabling the parasite evade host immune responses and prolong infection. These molecules mediate binding of IEs to host endothelial cells and uninfected erythrocytes. Cytoadhesion of IE to host cells leads to sequestration in tissues and PfEMP1 is thought to play an important role in parasite virulence. Here we analysed 1725 sequence tags sampled from the DBLa region of PfEMP1 encoding “var” genes from 27 patients in two different geographical regions in Kenya, Mbita in Western Kenya and Twiga on the Kenyan coast. The objective of this study was to construct a network to assess the extent of shared position specific polymorphic blocks (PSPBs) in sequences isolated from genomic DNA of field isolates from the two malaria endemic sites in Kenya.. Sequences from Mbita study site and those from Tiwi largely clustered into separate giant networks with only a limited number of sequences from the two sites linking to each other. This observation suggests that the parasite populations from the two endemic sites could be genetically varied and that PfEMP1 sequencing could be a useful tool of understanding the genetics of parasite populations. Thus the network approach of studying relationships between DBLα sequences is a useful tool of uncovering the genetic structure of parasite populations circulating in different malaria endemic regions. Keywords: PfEMP1, Networks, Position Specific Polymorphic Groups, DBLα, Malaria, P. falciparu

Symptom- and Laboratory-Based Ebola Risk Scores to Differentiate Likely Ebola Infections.

Rapidly identifying likely Ebola patients is difficult because of a broad case definition, overlap of symptoms with common illnesses, and lack of rapid diagnostics. However, rapid identification is critical for care and containment of contagion. We analyzed retrospective data from 252 Ebola-positive and 172 Ebola-negative patients at a Sierra Leone Ebola treatment center to develop easy-to-use risk scores, based on symptoms and laboratory tests (if available), to stratify triaged patients by their likelihood of having Ebola infection. Headache, diarrhea, difficulty breathing, nausea/vomiting, loss of appetite, and conjunctivitis comprised the symptom-based score. The laboratory-based score also included creatinine, creatine kinase, alanine aminotransferase, and total bilirubin. This risk score correctly identified 92% of Ebola-positive patients as high risk for infection; both scores correctly classified >70% of Ebola-negative patients as low or medium risk. Clinicians can use these risk scores to gauge the likelihood of triaged patients having Ebola while awaiting laboratory confirmation